control of curing light of dental system microcontroller ali hussein hamed/al-khwarizmi engineering journal, vol.2, no. 1,pp 78-84 (2006) 87 al-khwarizmi engineering journal al-khwarizmi engineering journal, vol.2, no.1,pp 78-84, (2006) design and implementation of microcontroller based curing light control of dental system. ali hussein hamed information eng. dept. al-khawarizmi college of engineering university of baghdad (received 14 august 2005; accepted 4 april 2006) abstract: in this paper, a microcontroller-based electronic circuit have been designed and implemented for dental curing system using 8-bit mcs-51 microcontroller. also a new control card is designed while considering advantages of microcontroller systems the time of curing was controlled automatically by preset values which were input from a push-button switch. an ignition based on pwm technique was used to reduce the high starting current needed for the halogen lamp. this paper and through the test result will show a good performance of the proposed system. keywords: microcontroller, dental curing system, electronic circuit. 1.introduction the curing process in dental system is cured depending on the material used between 10 and 60 second in step of 10 second using blue beam light from a light source. the existing types of cards utilize analogue-controlled time features like time control and light intensity control. some disadvantages of these systems can be stated as complexity, low reliability, high cost and big size. this control cards consist of several circuit components, thus can be fairly complex and clumsy. these control cards are mounted on two or more separate boards because they just do not fit in a single board. the new design is compared with other existing system; the major advantages of the new designed system are the following the small size of the system, programmable, simple, reliable, and low cost. the 12v, 75 watt halogen lamp, the source of the light is controlled by a power transistor with a pwm mode provided by the microcontroller. by using this technique, the starting current needed for the lamp is reducing. consequently, the desired curing process for the dental system is obtained. the new control card can be also fit in a single board because there are a few circuits used by the design, which reduce the cost and the noise level during its operation. 2.the system characteristics the designed system is a light curing unit for interiorly polymerization of dental materials that can be shown in fig(1). the system is a hand-held, corded. the visible light polymerization system consist of a pistol-style hand piece attached via a 1-m cord to the power unit and the power unit contains a ali hussein hamed/al-khwarizmi engineering journal, vol.2, no. 1,pp 78-84 (2006) 87 built-in digital controller and d.c power supply. the activation on/off control exposure time selection switches and sevensegment display are conveniently located on the power unit. the hand piece comes with quartz-halogen lamp and a 10-mm curved curing wand. a thermister was used near the halogen lamp which will interrupt the microcontroller when the temperature of the lamp goes to a high value, then the microcontroller will turn the fan on to minimize unnecessary fan operation and noise. 3.the system implementation among curing light control system, one of the most reliable ones is the microcontroller type. the microcontroller and halogen lamp power supply designed for positive voltage of 5v and 12v using lm7805s and the power lm317 voltage regulators respectively, as shown in fig.(2). selection of resistors r1 and r2 allow the setting of the output to any desired voltage over the adjustment range ( 1.2 to 37 v). the output voltage desired can be calculated using : 2 1 2 )1( ri r r vv adjrefo  with typical values of vref=1.25 v and iadj= 100 µa. for a 12 v, the values of the resistors r1 ( which act as a current sensor) and r2 are 220ω and 2kω respectively. the control card circuit diagram is shown in fig (3). microcontrollers require one or more power supply voltages, these voltage values should be kept in the 5% margin of operation limits. in order to display a 2-digit decimal number indicate the time of curing in seconds, a seven-segment display units is used. also we used the 7447 driver/converter to prevent the vibration of the leds. each display has a common cathode and controlled by a single transistor driven from the microcontroller. a heat sensor, the thermister, have been putted near the halogen lamp which runs as a switch, when the lamp temperature rise above 75 ْ c the thermister will contact enabling the interrupt of the microcontroller, the microcontroller will stop its convent work, turning off the lamp and turn on the fan is in order to cool the system. this is an important feature provided by the new design using microcontroller, which will protect the system from damage and make the work safely. three push button switches are provided with the system located in the front panel two of them are used to select the required time for curing. by pressing the increment switch the seven segments will display the time in seconds, each press will increase the time 10second. the decrement switch is opposite to the increment one. the start switch is press when the required time is selected, this switch shall run the halogen lamp. 4.the software solution in this work a problem has been occur during the test of the system, when the power is turn on the system work normally, once the halogen lamp is turn on, the microcontroller is reset. the reason for this case is that the lamp when work in its rating consuming a current of 6 ampere, when it is worm, but the starting current is much more than this by two or three times, thus the d.c. voltage of the power supply will drop very fast causing restart of the microcontroller. many solutions to this problem was introduce, one of these solutions is to use a power supply dedicated for the halogen lamp, but this will lead to make the system size bigger with high cost. a pulse width modulation pwm technique is used to solve this problem by using the benefit of microcontroller. a worm software subroutine was built; by this a frequency of 4.9 mhz (2040 μ sec.) was produced. for the first period a pulse of on about 8 μ sec. width is given to the halogen lamp then the lamp is turn off for a period of 2032 μ sec, as shown in fig (4-a-), for this pulse the d.c. supply voltage will not drop. in the next period a pulse of 16 μ sec. is on and 2024 μ sec off and so on. this technique would continue for 0.5 sec, after this time the voltage input to the transistor of the lamp is ali hussein hamed/al-khwarizmi engineering journal, vol.2, no. 1,pp 78-84 (2006) 78 stay on for the required time of curing 10, 20, 30,.. sec. as shown in fig.( 4-a-). 5.the test result by using this technique the duty cycle is changing linearly by a figure of 0.4 % .where the duty cycle is offon on tt t dutycycle   in the first period the duty cycle is 0.4% and increasing each cycle by this value. by this the lamp will worm in about 0.5 sec. fig (4-b) shows the current rising through the worm time and then stay at steady state for the rest time. fig.(4) explain the starting current without using the pwm technique, these result was obtained practically using digital storage oscilloscope. 6.the conclusions the four most important results of this study for the purpose of controlling of light curing in dental system are usage of microcontroller in the control card, the small size of the system, the full reliability of the control card comparing to its relatives, using the new software solution for the hardware problem. the control card of the early equipment is semi-mechanical. timing values are input from potentiometer. the most sophisticated control card that is in use is designed with the digital design techniques. in this designed system a smaller amount of the circuit component is used and all of them are placed on one card. 7.references 1) metin kapidere, serdar muldur, and inan guler, control of dental prosthesis system with microcontroller, jornal of medical system, vol. 24, no 2, 2000. 2) cyril w. lander, power electronic, second edition, mcgraw-hill, 1987. 3) mike james, microcontroller cookbook, prentice hall, 1997. 4) gene f. franklin, david powell and michael workman, digital control of dynamic system, third edition , prentice hall, 1998. 5) pei an, pc interfacing using centronic, rs232 and game ports,newnes, 1998 ali hussein hamed/al-khwarizmi engineering journal, vol.2, no. 1,pp 78-84 (2006) 78 fig(2) schematic digram of the designed power supply 1 2 3 4 5 6 a b c d 654321 d c b a title n u mber r ev is io nsize b d ate: 21 -jan -20 06 sh eet o f fi le: c : \my d o cu ~1 \a li .s ch d raw n b y : b r id g e1 b r id g e2 47 0 uf c 25 0 uf c 2 2 0 v transfo rmer v in 1 a d j 2 +v ou t 3 lm31 7h v in 1 g n d 3 +5v 2 lm78 05s 0 .01 uf c + 5 vo lt 15 vo lt 15 vo lt r 1 22 0 r 2 2 k 0 .01 uf c + 12 vo lt ali hussein hamed/al-khwarizmi engineering journal, vol.2, no. 1,pp 78-84 (2006) 78 1 2 3 4 5 6 a b c d 654321 d c b a title n u mb er r ev is io nsize b d ate: 7 -a ug -2 0 05 sh eet o f fi le: c :\a li\s ch ema ti.sc h d raw n b y : 1 2 3 4 5 1 0 9 8 6 7 1 1 1 2 1 3 1 4 1 5 1 9 1 8 1 7 1 6 2 0 1 2 m h z u1 10 uf 8 .2k v cc 1 k v cc b d 91 11 k 25 612 v v cc v cc r st p3 .0 p3 .1 x 1 x 2 p3 .2 p3 .3 p3 .4 g nd p3 .5 p3 .7 p1 .0 p1 .1 p1 .2 p1 .3 p1 .4 p1 .5 v cc p1 .7 p1 .6 v cc 1 k 1 k v cc 1 k v cc th er miste r b uz zer 30 pf 30 pf 12 v light cure controller/controller mps a92 b c 6 3 6 b c 63 6 h al lo gi n ligh t(1 2 v,50 w ) b c 63 9 + mps a9 2 \i nt 0 b c 63 9 f an a b c d d 1 d 2 w ith heat s in k 89 c 20 51 u 1 q 4 q 3 q 1 q 2 q 5 q 6 q 7 r 1 r 2 r 3 r 4 r 5 r 12 c 2 c 3 c 1 r 11 b u z1 1k v cc st ar t sw 3 r 8 a 7 b 1 c 2 d 6 b 1 4 lt 3 r b 1 5 a 1 3 b 1 2 c 1 1 d 1 0 e 9 f 1 5 g 1 4 74 47 v cc bafg d pcde d i s2 bafg d pcde d i s1u 2 1 k1 k v cc st an d by led 1 k + _ v cc f la sh l ed 1 k v cc r 6 r 7 le d1le d2 sw 2 sw 1 r10 r9 fig (3) circuit diagram of the control card. ali hussein hamed/al-khwarizmi engineering journal, vol.2, no. 1,pp 78-84 (2006) 78 time sec. 2000μ sec 1992μ sec 48 μ sec 56 μ sec 64 μ sec time sec. 2032μ sec 2024μ sec 8 μ sec 2032μ sec 16 μ sec 24 μ sec 32 μ sec 2024μ sec 2016μ sec 2008μ sec 40 μ sec vin(t) 2016μ sec time sec. ali hussein hamed/al-khwarizmi engineering journal, vol.2, no. 1,pp 78-84 (2006) 74 current of the lamp i(t) fig (4) schematic diagram of the pwm technique. a) the voltage input to the base of the power transistor driving the lamp. b) the current of the lamp during the warm and steady state. 0.5 sec. 10, 20,.. sec 10, 20,.. sec current of the lamp i(t) -b -a 6a fig (5) the starting current of the lamp without pwm technique. 6 a time sec. time sec. ali hussein hamed/al-khwarizmi engineering journal, vol.2, no. 1,pp 78-84 (2006) 78 تصميم و بناء دائرة معالج دقيق للسيطرة على منظومة التجفيف الضؤي لألسنان علي حسين حمد قسم هندسة المعلومات كلية هندسة الخوارزمي جامعة بغداد :خالصةال في هذا البحث تم تصميم و بناء دائرة الكترونية باستمال المسيطر الدديي تسدتخدم لنمدام تف يدو حادوة ا.سدنااس تدم اسدتحداث دائرة فديدة ما خالل ا.ست ادة ما فوائد المسيطر الديي س تمت السيطرة على الويت المطلوب للتف يو ما خالل ييم تعطى الى الضغطةس تم ايقداد مصدباا الولدوفيا المسدتعمل فدي التف يدو بطريقدة تضدميا عدر النبضدة المسيطر مسبقا باستعمال م اتيح وذلددل للتقليددل مددا تيددار البدددء العددالي الددذا يحتافددم المصددباا لكددي يعمددلس هددذا البحددث و مددا خددالل نتددائ ال حدد بدديا داء فيدددا للمنمومة المقترحةس final suha mohammed hadi /al-khwarizmi engineering journal ,vol.1, no. 1,pp 46-51 (2005) ٤٦ al-khwarizmi engineering journal al-khwarizmi engineering journal, vol.1, no.1,pp 46-51, (2005) a new approach for designing multi information management system using xml technology dr. suha mohammed hadi information engineering dept./al-khwarizmi engineering college/universityof baghdad abstract xml is being incorporated into the foundation of e-business data applications. this paper addresses the problem of the freeform information that stored in any organization and how xml with using this new approach will make the operation of the search very efficient and time consuming. this paper introduces new solution and methodology that has been developed to capture and manage such unstructured freeform information (multi information) depending on the use of xml schema technologies, neural network idea and object oriented relational database, in order to provide a practical solution for efficiently management multi freeform information system. keyword: free form information, xml technology, data modeling, relational data base. introduction: it is estimated that in most businesses over 80% of all information is in unstructured or freeform format. a huge proportion of corporate memory is therefore captured in freeform format. capturing and managing this information in a computer system offers great potential for improving efficiency and resource utilization increasing innovation and competitiveness by retaining the corporate know-how and memory, helping gain deep insights and understanding into the business environment. this is a key component of the knowledge management discipline and the digital or knowledge economy [1]. the advent of the world wide web in the 1990s has resulted the publication of millions freeform documents in digital form. such free-form information is difficult to manage [2]. the information is diverse in nature, complex, and subject to frequent changes. traditionally, forms are used to ensure that relevant information is captured by providing structures and checklists. forms are especially important when the same type of information is captured repeatedly [3]. in the paper world, we often make copies of the documents so that we can put them in the folders required. this creates its own problems, as comments made on one copy will not be visible in the other copies. follow-up documents also may not be filed in all the folders. unfortunately such storage systems do suha mohammed hadi /al-khwarizmi engineering journal ,vol.1, no. 1,pp 46-51 (2005) ٤٧ not support the information usage model. documents may be classified into many categories and related to each other. in the computer world, the filing system should be virtualized where we have only one copy of the document but visible in as many categories as required. freeform information without structure is difficult to manage. and lack of structure dramatically reduces an organization’s ability to leverage the value of such content. the simplest and most common form of information storage and management is to store documents as files in folders and use the directory structure as the means of navigation. with more advanced systems, the documents are stored in databases where they may be indexed to provide full-text search facilities [4]. the purpose of our proposed information management system is that to be useful for any organization in various purposes including training and reference, planning, design, innovation and decision-making processes. to meet these requirements we have to look beyond information access and full-text search facilities. users of the information must also be able to gain insights and deep understanding on the subjects of interest. the facilities provided by this model must assist the users in discovering new information from the unified view of the information available. 1. xml technology the extendable markup language (xml) is an open standard for defining data elements on business documents. it defines the structured information those elements contain. xml was originally developed as an application profile of standard general markup language (sgml) to use over the internet. but the ease of both writing applications that process xml document and creating xml documents has made xml an instant success for a variety of other application domains, too. in fact, one area where the benefits of xml have become immediately apparent is data exchange and data modeling. there are clear benefits from using xml in these areas. • first, the design of xml is formal and concise, so it's relatively easy to write structured data. • second, since xml documents are human-readable, a developer can figure out what the content means by simply inspecting the xml document. • third, momentum is building to create standardized xml protocols (also referred to as xml schemas) for almost any type of business. so there's an excellent chance that in the near future a majority of transactions will be carried out using xml as the underlying infrastructure protocol. this shift from binary protocols to xml-based protocols resembles the computing industry's move from mainframe-centric terminals and central processing units to the client/server paradigm of distributed computing. like client/server before it, xml requires new ways of storing data. in the shift from mainframe-centric to client/server computing, a major side effect was the development of relational database servers. similarly, in the case of the move to xml protocols, there is a noticeable trend toward not only exchanging xml data, but also storing it directly as xml data [5]. 2. designing the new approach before the information can be managed it must be captured first. the bulk of freeform information available suha mohammed hadi /al-khwarizmi engineering journal ,vol.1, no. 1,pp 46-51 (2005) ٤٨ today is unstructured. with xml technology, the structure form can be imposed on most kinds of information. this technology trend is to capture as much of such information as possible. in order to use conventional technology, for each form, we require a software program or a program unit to create the user interface, define the data types, validation rules and posting processes. often, enumerated lists and lookup tables are also required to provide codified information for some fields. by using this technology, the information has to be stored in relational database tables, which will run into thousands as the information in each complex form will have to be posted into several normalized relational tables. all this must be designed with some considerations that may influence the development of such data capture systems. our new approach schema forms is designed to address the issues mentioned above. it is xml driven and based on xml schema, with these schema forms, the data entry forms are generated from xml schema documents that define the data types, limits, enumerated lists and other constraints. effectively, schemaforms can handle an unlimited number of forms based on the user-defined xml schema. a diagrammatic representation of the new approach design process can be shown in fig. 1. . fig. (1): the basic function design for the schema form the output from the data entry starts as an xml document that can be distributed to a distribution list, stored in a local database, posted to an open database connectivity (odbc) compliant relational database. the distribution and posting can be conditional based on the contents of the document, this is a facility made possible by xml technology. the xml schema documents are userdefined; they can be defined with any other xml schema tools. the process in our design is a user-driven, because we can define the schema and the distribution and posting instructions, which make the process fast, efficient and cost effective. as the xml schema is in pure ascii, they can also be easily distributed. the whole process can be done offline and together with the local database storage, supports the long transaction requirements described above. 3. the new information model architecture in order to perform the new proposed information management system we recognize that these documents should be stored as an information network where any document can be connected to other documents. instead of trying to handle the network conventionally, this new information model has been designed as an inverse of the network whereby any node (knowledge object) can be selected as the centre of focus, and lists represent related objects based on relationships. the tenets and the architecture of this multi information model are as the following: schema me user interf pro ma nua xml doc distr ibuti od bc loc al suha mohammed hadi /al-khwarizmi engineering journal ,vol.1, no. 1,pp 46-51 (2005) ٤٩ 1. information is represented as objects. an object represent anything that can be given a name, e.g., a concept, a person, an organization; 2. every object can be the centre of focus with all related objects made visible i.e., there can be as many perspectives as there are objects. this object can also be viewed as a tree with the branches expanded to any level (subject to system resources) as explained in fig. 2. 3. all objects are equal. an object can have more than one name and more than one description. any list of objects can be filtered, clustered or expanded based on the relationships defined in the network. the lists also represent additional perspectives. so that they can be dynamically rearranged without losing context. 4. the common set search feature allows users to find common sets from a list of objects based on the set theory. objects can be related to each other as groups and members (i.e. related in hierarchical structures or generic relationship). 5. objects can be associated with each other, the connectivity search feature allows user to find the connections between any two objects through multiple levels. to make this search more meaningful, selected relationships and objects can be excluded from the search. xml-based document search allows users to find text within specific nodes of documents. 6. objects can also be classified into themes; the data query allows selected information to be extracted for display purposes or to other formats for processing which can be also referred as layers that can be shown in fig (3). fig. (2): the maine interfaces between objects fig. (3): the thematic map concepts the concept or the knowledge of the new proposed model represented as a network of information object that is defined in xml and based on relational database technology. a schema document (say b) can reference another schema (say a). in this model, the system will allow the obje ct obje ct obje ct obje ct obje ct lower base count peop produ organizati on base suha mohammed hadi /al-khwarizmi engineering journal ,vol.1, no. 1,pp 46-51 (2005) ٥٠ definition of document mapping i.e. retrieval of specific nodes from schema “a” documents to schema “b” documents. in our model while viewing a document of schema “a”, there will be an option for the user to launch schema-forms with a new entry form based on schema “b”. the information from the viewed document will be transferred to the entry form based on the nodes mapping defined. since the posting of documents in schema-forms can be conditionally defined, the schema “b” document can be added as another document to the schema “a” document and update the relationships of the object containing the schema “a” document. alternatively, the schema “b” document can be posted as a new object related to the schema “a” document. these powerful userdefinable model features allow the development of generic document workflow applications rapidly using xml schema-forms for a variety of purposes. 4.conclusions developers today are challenged to integrate their applications with other systems over a network. oftentimes these other systems are deployed on disparate platforms and are written using disparate programming languages. xml has quickly become the defacto standard for exchanging data between systems; possible solutions for consuming xml documents including using low-level generic parsing applications have been developed. using xml object link offers the ability to easily handle xml documents that can readily be exchanged with other systems, including those based on different languages. information technology is the key to the knowledge management and the knowledge management has the potential to help the organizations innovate, make better decisions and improve their competitiveness. a unified approach in managing information has been designed which capture divers information in a single database that the user can navigate, explore, expand, filter and analyze. making every thing visible because information is only useful if we can see what is really there. the xml-driven solution model that we proposed provides a viable platform for the capture, management, distribution and publishing of enterprise information. xml is an emerging technology that committed for enterprise information management as they become available. this approach has stood the test of time. the new multi information management solutions can be used on desktops and within local area networks. references 1. xml style sheet language transformation (http://www.w3.org/tr/xslt), 12-3-2004. 2. extensible markup language (http://www.w3.org/tr/recxml), 05-12-2001. 3. human computer factors (users and information systems), andy smith, (1997), washington dc, usa, pp 14, 87, 117. 4. model driven architecture, joaquin miller and jishnu mukerji, modeling design journal, architecture board ormsci, 9-july2001, uk. 5. oracle/ xml sql utility, http://www.oracle.com/techn ology/tech/xml, 22-01-2003. http://www.w3.org/tr/xslt) http://www.w3.org/tr/rec http://www.oracle.com/techn suha mohammed hadi /al-khwarizmi engineering journal ,vol.1, no. 1,pp 46-51 (2005) ٥١ xml طريقة جديدة لتصميم نظام الدارة المعلومات المتعددة باستخدام تكنلوجيا ال سها محمد هادي.د جامعة بغداد/كلية هندسة الخوارزمي/قسم هندسة المعلومات :الخالصة لكثير من تطبيقات قواعد البيانات الخاصة باالعمال تم اشراكها في البناء االساسي xmlان تكنلوجيا ال االلكترونية حيث يتناول هذا البحث مشكلة المعلومات ذات التكوين الحر التي تخزن في اي منظمة او مؤسسة وكيفية مع هذه الطريقة المقترحة والتي سوف تجعل عملية البحث عن المعلومات ذات كفاءة اكثر وبأقل xmlاستخدام ال .وقت ممكن اي ( ان هذا البحث يعرض طريقة حل جديدة مطورة المساك والدارة مثل هذه المعلومات الغير مهيكلة والحرة لشبكات العصبية وقواعد البيانات الشيئية ومبدأ ا xmlوالمعتمدة على استخدام تكنلوجيا سكيما ال ) المتعددة . لغرض توفير حل عملي الدارة كفوءة النظمة المعلومات المتعددة الحرة د.نبيل وعامر al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 9, no. 1, p.p. 1-8 (2013) enhancing stud arc welding technique vai utilizing fuzzylogic approach (fla) nabeel k. abid al-sahib* amer a. moosa** * university of thi-qar **department of manufacturing engineering/ alkhwarzmi college of engineering/ university of baghdad *email:n_k_alsahib@yahoo.com **email:amermoosa@yahoo.com (received 6 june 2011; accepted 20 december 2012) abstract a fuzzy logic approach (fla) application in the process of stud arc welding environment was implemented under the condition of fuzziness input data. this paper is composed of the background of fla, related research work review and points for developing in stud welding manufacturing. then, it investigates thecase of developingstud arc welding process on the controversial certaintyof available equipment and human skills.five parameters (welding time, sheet thickness, type of coating, welding current and stud shape) were studied.a pair of parameter was selected asiteration whichis welding current and welding time and used for verification corresponding with tensile strength as output results and this willconsider it as schema for other cases.the testing result in the case of crisp (exact) value verifyingied the uncertainty value of some criteria selected which open the concept to make the decision making process for some advance cases without implementation. this paper applied the proposed methodology using matlab program, the graphic user interface (gui) fuzzy tool box for the case study of screw dabotekstud welding machine, for 6 mm diameter stud. the sheet materials are (k14358 and k52355) according to (usn standards, and the stud materials are (54nicrmos6 and 4ocrmnmos8-6) according to (din standards).this given information is very inevitable for the conventional crisp determination of the tensile stress for the particular specimens experimented and also for verifying the tensile test value estimate in the case of changing to a fuzzy value for two of the input variables. keywords: stud arc welding,fuzzy logic approach, fuzziness, crisp,gui. 1. introduction stud arc welding is a widely used operation in mechanical structure, where high tensile strength with minimum variation is required. the variation of tensile strength affects the cost of stud welding unit operations such as rework and time consume. these are often limiting steps in mechanical manufacturing processes; therefore, significant cost reduction can be realized by producing the stud welding joint having reliable tensile strength ( jibsonj 1997)[1]. usually, to find the influence of controlling parameters on welding process a large number of experiments needed. in order to avoid this, fuzzy logic approach fla methods can be used as a decision making process for the adequate solution of experiments. the classical method of experiments emphasizes prediction of future behavior of experiments from empirical model while running a fraction of full factorial of the combination parameters which are very sophisticated. the variation in the stud arc process, may be due to any or a combination of a selective five sources. so some of these source are srelated to machine, measurement, method, material, manpower, stud, sheet, power supply, and environment, etc. for this study of stud arc welding the effect of manpower on variation is limited because the machine is operating in a semiautomatic process, also the experiments wear mailto:email:n_k_alsahib@yahoo.com mailto:amermoosa@yahoo.com nabeel k. abid al-sahib al-khwarizmi engineering journal, vol. 9, no. 1, p.p. 1-8 (2013) 2 executed onsort of or semi laboratory environment. problem identification is very important for any industrial experiment. one of the most used methods for identifying the problem is brainstorming. brainstorming is an activity that promotes team participation, encourages creative thinking and generates many ideas in a short period of time. for an investigation into the possible causes of the undesirable variability in the stud welding process, a cause-and-effect diagram that lists several suspected causes of this variability is shown in figure (1)[7]. fig. 1. control factors of stud welding cause-and-effect diagram. 2. crisp factor levels and fuzziness range of factor setting determining the membership function of selected factors from brainstorming is a major concern to many researchers in industries. abrainstorming session suggested using five factors with particular two pairs of them in the fuzziness / defuzziness method. after determining the number required for each factor, it is needed to specify the fuzziness range of operation for each control factor. it is usually best to experiment the largest range feasible, so that the variation inherent in the process does not mask the factor effects on the response. the crisp membership function for welding time and welding current are shown in table (1), and the list of the rest three factors taken into consideration on the traditional crisp method experimental were changed in the conventional test to obtain the tensile stress values, see table(2). this action was taken to get more measurement of tensile test which was already verified as exact. the same concept was established with two of the inputs to verify the result as in the crisp case when taken the range for these particular two variables, so that for the fuzzy approach the selected factor table (1) was chosen as a keystone for the huge amount of constrain like those in cause and effect diagram control factors which are shown in figure (1). table 1, welding time/current membership function range time: 0.15 0.2 – 0.25 – 0.3 – 0.35 unit in second welding current: 350 – 450 unit in amp table 2, other factors factors unit range sheet thickness mm 1.6 – 3.175 type of coating k52355 k14358 mm 0.3 0.75 stud shape none small stud flange stud nabeel k. abid al-sahib al-khwarizmi engineering journal, vol. 9, no. 1, p.p. 1-8 (2013) 3 once the factors were decided, the membership function for each factor was selected. selection of membership function depends on how the outcome (tensile strength) is affected and verification the different member and that was achieved by taking six values within the factors shown in table (3) and acquiring the tensile test result in the crisp case, for example the set of (0.15s time, 1.6 mm sheet thickness, 350 amp welding current, 0.3 mm coating type, small stud shape) will generate (175.73, 288.70, 284.39, 359.99, 190.70) n/mm² respectively. table 3, stud arc welding tensile strength. 3. fuzzy logic programming methodology fuzzy logic is a logical system, which is an extension of multivalued logic. however, in a wider sense fuzzy logic (fl) is almost synonymous with the theory of fuzzy sets, a theory which relates to classes of objects with non-sharp boundaries in which membership is a matter of degree. (mathwork2010)[6]. however, using the gui guide user interface to obtain the number of input and output and inference engine domain containing the membership function curve that concurrently describe the behavior of each variable corresponding with rule that reflect stud welding machining demand for this case study, the carrying out of the following steps are inevitable figure (2). step 1 (input): for the welding current thegaussian function (gaussmf) [5] was used, two of them representa single value as shown in figure (3). step2 (input): for the welding time the trapezoidal function (trapzmf) [5] was used, three of them represent a single value see figure (4). step3 (output): for tensile strength the triangular function (trimf) [5] was used, three of them on representsa single value see figure (5). (for coated type in fuzzy range the value of its tensile stress was ignored to get more accuracy and it did not affect the manipulation as checked on its availability in crisp case). step 4: the data could be entered in term of numerical symbols or simply adjust the line (move by using computer mouse) from the guide user interface screen see figure (6). step 5: the case of defuzziness output could be numerically recognized or from the surface of 3d dimension see in figure (7). factors tensile strength n/mm² mean n/mm² time 175.73 213.23 143.66 195.09 210.50 155.60 182.302 sheet thickness 288.70 251.20 330.40 284.99 225.90 300.70 280.315 welding current 284.39 198.56 225.89 245.87 276.24 263.54 249.082 type of coating 359.99 420.50 428.42 300.03 387.38 367.54 377.310 stud shape 190.70 245.87 235.90 298.46 164.33 289.46 237.453 nabeel k. abid al-sahib al-khwarizmi engineering journal, vol. 9, no. 1, p.p. 1-8 (2013) 4 fig. 2. fuzzy reasoning methodology steps. fig. 3. welding current membership. output tensile test crisp output tensile test in fuzzy range two membership function (gaussmf) two trapezoidal function (trapzmf) input welding time range and welding current specify the range of data for both inputs (fuzzy) entering num. or by mouse ant data with the range of input nabeel k. abid al-sahib al-khwarizmi engineering journal, vol. 9, no. 1, p.p. 1-8 (2013) 5 fig. 4. welding time membership. fig. 5. tensile strength membership. nabeel k. abid al-sahib al-khwarizmi engineering journal, vol. 9, no. 1, p.p. 1-8 (2013) 6 fig. 6. defuzziness input/output interface. fig. 7. three dimension surface viewing. nabeel k. abid al-sahib al-khwarizmi engineering journal, vol. 9, no. 1, p.p. 1-8 (2013) 7 4. discussion and conclusion after interpreting the results of the analysis, it is advisable to ensure that the experimental conclusions are supported by the data in both the crispness and the fuzzy cases. the confidence interval of each set of variables range is the varianceof the estimated result inthe in between value or simply in the fuzzy condition. so that the result inthe tensile stress to be reasoning distributed was selected in the range of (l75 to 250) n/mm²which is already verified in the crisp or conventional method. the confirmation experimental is used to verify whether the predicated output responseonthe tensile stress based on the same levels of the combination of factors (variables) range and here two of which could called main factors entered with no exact value and that could be localized for whole welding environment where this could show extreme benefits for others more sophisticated cases with the lackof some processes information. if conclusive results are obtained from the confirmation run, a specific action on the process may be taken for improvement. a confirmatory run/experiment (or follow-up experiment) is necessary in order to verify the results from the statistical analysis (for future work). this is to demonstrate that the factors and levels chosen for the influential do provide the desired results. the insignificant factors should be set at their economic level during the verification run/experiment. however, observations with some out of range data for the general experimental essentially for the crisp situation and continuing in the particular range the fuzzycondition and this could be seen as a flow: 1. welding: time this factor strongly effects on tensile strength measure. the mean value of tensile strength in levels (0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, and 0.5). 2. sheet material: this factor explicitly affects the welding process and the mechanism of joint product where it has a wide range of levels. 3. stud material: this factor also effects in the stud welding process, the different value of tensile strength varies from one level to another. 4. sheet thickness: increasing sheet thickness; a thicker sheet is stiffer during mechanical testing and this minimizes the peel characteristic of the tests and increases strength. 5. welding current: this factor has the smallest effect factor where the effect of tensile strength in the level range (350 ampere) is 278.73 n/mm² for an instant. 5. references [1] jibsonj.”advance welding”, john wiley & sons, 1997. [2] montgomery d.c” design and analysis of experiments” second edition john wiley &sons, inc., 2001. [3] hu ping, bo jun (weihaicampus,harbin university of technology,weihai,264200,china) anew stud welder bolt welder in generating arc by computer auto-detecting http://en.cnki.com.cn/journal_en/c-c000 jlgy-2001-03.htm. [4] 4arabshahi, p.; marks, r.j., ii; seho oh; caudell, t.p.; choi, j.j.; bong-gee song; jet propulsion lab., california inst. of technol., pasadena, ca + arabshahi, p.+m pointer adaptation and pruning of mini-max fuzzy inference and estimation ieee volume: 44 issue: 9 issn: 1057-7130. [5] l. a. zadeh the adoption of fuzzy logic in the mathematics curriculum. .....controllers, controllers for robot arc-welders, stud., vol. 12, 1980, pp. 11-23 (1965). [6] nabeel. k.” taguchi experimental design and artificial neural network solution of stud arc welding process “university of baghdad college of engineering 2010. [7] m. j. arnest application to arc welding, in industrial processes," int. j. general systems, controller," int. j. man-mach. stud.7, pp.1-13. “in proceedings of i ee.2007 [8] samuel h. huang and hong-chao zhang neural-expert hybrid approach for intelligent manufacturing: a survey (elsevier)science direct volume 26, issue 2, may 1995, pages 107-126 [9] vahdani, behnam; hadipour, hasan; sadaghiani, jamshidsalehi; amiri, maghsoudextension of vikor method based on the interval value fuzzy set. springer, february 24, 2010. [10] shi bao-shan,li . fuzzy logic control strategy for submerged arc automatic welding of digital controllingcnki: sun: gwdz.0.pp-04-038-2009. http://en.cnki.com.cn/journal_en/c-c000 )2013( 18، صفحة 1، العدد9مجلة الخوارزمي الھندسیة المجلد نبیل كاظم عبد الصاحب 8 المظببتعظیم تقنیة لحام القوس المسماري بواسطة االنتفاع من مقاربة المنطق **عامر عبد المنعم موسى* نبیل كاظم عبد الصاحب *جامعة ذي قار جامعة بغداد/ كلیة الھندسة الخوارزمي /قسم ھندسة التصنیع المؤتمت** n_k_alsahib@yahoo.com :البرید االلكتروني* amermoosa@yahoo.com :االلكترونيالبرید ** ةالخالص في ھذا البحث . ان دراسة تطبیق لحام القوس المسماري باسلوب المنطق المظبب لمدخالت عملیة اللحام اثبتت فاعلیتھا في تحسین ظروف عملیة اللحام المجال و التطرق لبعض البحوث المتعلقھ بھذه العملیھ ونقاط التطور و التعزیز لصناعة لحام القوس المسماري ثم تم تطبیق اثر المنطق الظبابي في ھذا .لمكینة او مھارة اللحام ةبوجود عدم الدق ةعملی ةمقارنة ھذا مع تطبیق اللحام لحال لقد .حام ونوع التغلیف والجھد الكھربائي واخیرا شكل مسمار اللحام تم دراسة خمس نقاط اساسیھ لمدخالت عملیة اللحام وھي زمن اللحام وسمك لوح الل .للتیار المستخدم في عملیة اللحامتم اختیار اثنان من المدخالت لتدخل باسلوب المنطق المظبب لتولیفة مجموع المدخالت وھي زمن اللحام والجھد الكھربائي .صحیح للعملیھ التصنیعیھ بشكل عامووجد ھناك دقھ وت) ةالقیمھ الثابت( ةوالتقلیدی ةالحالتین المظببوللتحقق من صحة النتائج تم مقارنة المخرجات في كال تم استخدام برنامج الماتالب واسلوب واجھات .ونتیجھ لذلك مكن ھذا االمر من الحصول على عملیات اتخاذ قرار لبعض الحاالت دون تنفیذھا بشكل واقعي ملم للقطر ولوح معدني معیاري عالمي مع التحقق من ٦بسمك ةمعیاری ةمن المسمار وبمواصف ةمعین ةلبحث تم استخدام ماركالمستفید للمحاكات ولھذا ا . لعملیة اللحام ةوالمظبب ةمن خالل فحوصات الشد لعینات مختاره ولكال الحالتین القیمھ الثابت ةالتصنیعی ةمجمل العملی mailto:n_k_alsahib@yahoo.com mailto:amermoosa@yahoo.com تغريد al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 7, no. 4, pp 54-60 (2011) back stepping-based-pid-controller designed for an artificial pancreas model taghreed m. mohammad ridha mina qais kadhum shaimamahmou mahdi department of control and systems engineering /university of technology email: teeta.control@yahoo.com (received 2 march 2011; accepted 20 september 2011) abstract artificial pancreas is simulated to handle type i diabetic patients under intensive care by automatically controlling the insulin infusion rate. a backstepping technique is used to apply the effect of pid controller to blood glucose level since there is no direct relation between insulin infusion (the manipulated variable) and glucose level in bergman’s system model subjected to an oral glucose tolerance test by applying a meal translated into a disturbance. backstepping technique is usually recommended to stabilize and control the states of bergman's class of nonlinear systems. the results showed a very satisfactory behavior of glucose deviation to a sudden rise represented by the meal that increase the blood glucose keywords: type i diabetes, backstepping, bergman’s model, oral glucose tolerance test. 1. introduction with more than 246 million affected people worldwide, diabetes mellitus is one of the most widespread diseases and causes 3.8 million deaths per year, similar to hiv/aids [1]. any patient that suffers from diabetes that does properly receives the insulin cure can lead to complications such as nerve damage, brain damage, amputation and eventually death. diabetes related complications are a worldwide epidemic with high medical, economic and social costs [2]. the normal blood glucose concentration level in the human body varies in a narrow range (70 110 mg/dl). if for some reason the human body is unable to control the normal glucose-insulin interaction (e.g. the glucose concentration level is constantly out of the above mentioned range), diabetes is diagnosed. as a result four types of diabetes are known: type i (also known as insulin-dependent diabetes mellitus), type ii (or insulinindependent diabetes mellitus), gestational diabetes and other special types, like genetic deflections [3]. type i diabetes mellitus is characterized by theinability of the beta cells of the pancreas islets to produceinsulin, which is essential for the uptake of glucose in themuscles and storage in the liver [1].as known, insulin dosing is divided into two divisions: basal and bolus insulin. the basal insulin is required for fasting conditions; while bolus insulin is calculated to correct for meals or hyperglycemia condition. both dosages should be adjusted over time. the development of external insulin infusion pumps as well as the introduction of rapid-acting insulin analogues has made automated intensive insulin therapy feasible [4]. automatic controllers are needed to adjust the insulin therapy according to the measurements of glucose concentrations as illustrated in figure (1). automatic control of insulin infusion rate especially for type i diabetes proved its ability to give satisfactory results. different types of automatic controllers are used in the literature. a. makroglou et al[5] introduced an overview of some of the mathematical models appearing in the literature for use in the glucose-insulin regulatory system in relation to diabetes, enhanced with a mailto:teeta.control@yahoo.com taghreed m. mohammad al-khwarizmi engineering journal, vol. 7, no. 4, pp 54 -60 (2011) 55 survey on available software. while l. kovács et al [6] presented a practical method for designing arobust controller to regulate glucose-insulin system for type 1 diabetic patients under intensive care. also l. kovács et al [7] investigated the possibility of using a reduced order estimator for the three-state minimal bergman model. f. h. el-khatib et al [8] used an automated adaptive glucose-control system to regulate blood glucose, and showedthe plausibility and practicality of closed-loop bloodglucose control using subcutaneous insulin and glucagon infusion in type i diabetes. g. marchetti et al [9] proposed a new glucose control strategy based on a novel combination of insulin boluses for meals and an improved pid control algorithm. h. kirchsteiger et al [1] showed that it is possible to improve the common treatment of type i diabetic patients by optimization of the time and quantity of single subcutaneous insulin injections. y. wang et al [4] proposed an algorithm can take advantage of frequent glucose measurement to design the basal and bolus insulin simultaneously. two modern robust control methods are applied by l. kovács et al [10] the minimal model of bergman: the disturbance rejection lq control or minimax control and the robust h∞ control. in this work back stepping based pid controller analyzed and simulated the three states bergman model which is the widely used mathematical model due to its simplicity. fig.1. feedback control for blood glucose. 2. bergman's system model several different models of diabetic systemsexist, for example the very detailed 21thorder metabolic model of sorensen. however, to have a system that on one hand, can be readily handled from the point of view of control design, but on the other hand represents the biological process properly, the bergman’s three-state minimal patient model is considered.[6,7,10] …(1) where g(t) is the plasma glucose concentration above the basal level gb (mg/dl), x(t) (1/min)is remote compartment insulin utilization, y(t) is the plasma insulin concentration above a basal value yb (mu/dl). the control variable is theexogenous insulin infusion rate, i(t) (mu/min), whereas the exogenous glucose infusion rate h(t) (mg/dl min)represents the disturbance.vl(dl) representsthe insulin distribution volume and p1, p2, p3, p4 represent the model parameters. as numerical values the authors worked with the numerical values determined by: p1 = 0.028, p2 = 0.025, p3 = 0.00013, p4 = 5/54, gb = 110, yb = 1.5, vl = 120[6].in order to linearize the system, its steadystate values are needed: g0 = x0 = y0 = 0, h0 = 0, and for i0= p4ybvl= 16.667,the system proved to be stable, controllable and observable [10]. 3. backstepping based pid controller a backstepping technique is proposed to backbone the design of the pid controller. backstepping is a technique developed during taghreed m. mohammad al-khwarizmi engineering journal, vol. 7, no. 4, pp 54 -60 (2011) 56 1990 by petar v. kokotovic and others, for designing stabilizing controls for a special class of nonlinear dynamical. these systems are built from subsystems that radiate out from an irreducible subsystem that can be stabilized using some other method. because of this recursive structure, the designer can start the design process at the known-stable system and "back out" new controllers that progressively stabilize each outer subsystem. the process terminates when the final external control is reached. hence, this process is known as backstepping[11]. to apply the backstepping approach, each of the three equations in (1) is considered separately. now starting from the first equation: the state is regarded as the plasma glucose deviation (mg/dl), the virtual input is the remote compartment insulin utilization (1/min) and the disturbance is the exogenous glucose infusion rate (mg/dl min). a p controller is designed with as a virtual input. the second equation considered which has the remote compartment insulin utilization as a state variable and the plasma insulin deviation as the virtual input is considered. the virtual input for the second system will be designed to regulate the error between the remote compartment insulin utilization , the state, and its value as a virtual input (desired value) in the first equation. again a p controller for the second virtual input is designed. finally, the actual controller will be used as a pid controller to regulate the difference between the plasma insulin deviation and its value as a virtual controller as shown in figure (2). in addition, consider the following: all the parameters in equation (1) are uncertain but bounded; the disturbance is unknown but a bounded quantity, namely …(2) and also, …(3) the two virtual controllers and the actual controller are bounded: ...(4) fig.2.back stepping based pid approach used with bergman's model. 4. simulation results bergman's model comes with an artificial pancreas with two inputs: the ingested glucose in plasma after a meal reflected by the disturbance function h(t) and insulin from an external injection i(t) that plays the controllers role. the disturbance function employed here is smooth, continuously differentiable, has zero initial conditions, easily implemented and physiologically accurate function [2]: …(5) where hmis the peak value, a, b, c are constants which determine the exact shape. figure (3) shows the normal behavior of bergman's model when exposed to the disturbance which is the oral glucose tolerance test ogtt. there is a monotonic rise in the basal blood sugar by 32 mg/dl until the normal insulin initially existed treats this rise and guide it again to its basal level within . figure (4) illustrates the disturbance of oral food ingestion model. the backstepping approach determines how to stabilize the subsystem using , and then proceeds with determining how to derive the real control action on i to make the next state drive to the control required to stabilize . taghreed m. mohammad al-khwarizmi engineering journal, vol. 7, no. 4, pp 54 -60 (2011) 57 fig .3. normal plasma glucose deviation in response to ogtt. fig.4. exogenous glucose infusion (ogtt). hence there are three control actions to stabilize each state backward. theactual input signal the insulin infusion rate is controlled by pid controller tuned to kp3 =0.0627, ki =0.0010, kd= 0.8240 to stabilize the plasma insulin deviation y(t), at this step a p controller is designed with to stabilize remote compartment insulin utilization , which finally derives the glucose deviation to the originusing unity proportional controller ( ) when the system issubjected to the meal disturbance illustrated previously; the glucose deviation response of figure (5) is obtained and the basal glucose level is illustrated in figure (6). figure (7) illustrates the insulin infusion rate while the other systems states are in figures (8, 9). fig.5. controlled plasma glucose deviation using backstepping based pid controller exposed to ogtt. figure (6): basal glucose level controlled by backstepping pid. taghreed m. mohammad al-khwarizmi engineering journal, vol. 7, no. 4, pp 54 -60 (2011) 58 fig.7. backstepping pid controlled insulin infusion rate. fig.8. plasma insulin utilization controlled by backstepping pid. the backstepping pid perfectly enhanced the glucose transient response to have a maximum peak of 0.8 mg/dl which is less than 1% of basal level gb=110, also it guided the blood glucose through controlling the insulin infusion rate to the basal level very fast in backstepping technique was very useful to gain this excellent behavior with the three control and stabilizing steps. fig.9. plasma insulin deviation controlled by backstepping pid . these results are compared to those obtained by l. kovács et al [10] who used modified minimax, lq and controllers to regulate insulin infusion rate as illustrated in table (1). table (1) controller settlin g time (min.) glucose peak (mg/dl) insulin infusion highest level (mu/min.) minimax 252 11.7 18.3 lq 374 24.6 17.5 456.25 16.5 33.25 backstepping pid 570 0.8 19 5. conclusions glucose deviation of bergman's model for artificial pancreas is regulated by designing backstepping pid controller that directs the insulin infusions rate which stabilize the other two states backward until the glucose deviation is driven to zero after it's excitation by a sudden meal disturbance function that represents the taghreed m. mohammad al-khwarizmi engineering journal, vol. 7, no. 4, pp 54 -60 (2011) 59 ogtt. excellent behavior is obtained on both aspects moderate speed and minimum overshoot. the results are compared to these presented by l. kovacs. the proposed controller proved a very efficient behavior by giving the lowest glucose deviation peak even less than 1% of the basal level in 213min. backstepping technique is very much recommended to control such class of nonlinear systems and it is a good base to design any controller like pid that was fairly capable of handling the regulatory problem. 6. references [1] h. kirchsteiger, l. del re, e. renard and m. mayrhofer, " robustness properties of optimal insulin bolus administrations for type 1 diabetes", hyatt regency riverfront, st. louis, mo, usa june 10-12, 2009. [2] j. geoffrey chase, z-h lam, j-y lee and ks hwang, " active insulin infusion control of the blood glucose derivative", seventh international conference on control, automation, robotics and vision (icarcv'02), dec 2002, spingapore. [3] a. györgy, l. kovács, t. haidegger and b. benyó, "investigating a novel model of human blood glucose system at molecular levels from control theory point of view ", acta universitatis sapientiae, electrical and mechanical engineering, 1 (2009) 77-92. [4] y. wang, , e. dassau, , and f. j. doyle, " closed-loop control of artificial pancreatic β-cell in type 1 diabetes mellitus using model predictive iterative learning control", ieee transactions on biomedical engineering, vol. 57, no. 2, february 2010. [5] a. makroglou, j. li , y. kuang, " mathematical models and software tools for the glucose-insulin regulatory system and diabetes: an overview", applied numerical mathematics 56 (2006) 559–573. [6] l. kovács, b. paláncz, b. benyó, l. török and z. benyó, " robust blood-glucose control using mathematica",ieee, new york city, usa, aug 30-sept 3, 2006. [7] l. kovács, b. paláncz and z. benyó , "design of luenberger observer for glucose-insulin control via mathematica", ieee embs, lyon, france august 23-26, 2007. [8] f. h. el-khatib, j. jiang, and e. r. damiano," adaptive closed-loop control provides blood-glucose regulation using dual subcutaneous insulin and glucagon infusion in diabetic swine", journal of diabetes science and technology volume 1, issue 2, march 2007. [9] g. marchetti, m. barolo, l. jovanovic, h. zisser, and d. e. seborg, " an improved pid switching control strategy for type 1 diabetes", ieee transactions on biomedical engineering, vol. 55, no. 3, march 2008. [10] l. kovács, b. paláncz, e. borbély, b. benyó and z. benyó, " robust control algorithms for blood glucose control using mathematica",actaelectrotechnica et informatica, vol. 10, no. 2, 2010, 10–15. [11] http//:www.wikipedia.org. http://www.wikipedia.org )2011( 5460 ، صفحة4 ، العدد7مجلة الخوارزمي الھندسیة المجلد تغرید محمد محمدرضا 60 مستند على الخطوات التراجعیة مصمم -تفاضلي-تكامليمسیطر تناسبي لنموذج بنكریاس صناعي شیماء محمود مھدي مینا قیس كاظم تغرید محمد محمدرضا الجامعة التكنولوجیة/ سم ھندسة السیطرة والنظمق teeta.control@yahoo.com : االلكتروني البرید الخالصة ریاس صناعي لیتم معالجة مرضى النوع االول من مرض السكري تحت الرعایة الخاصھ عن طریق السیطرة االوتوماتیكیھ على تم تنفیذ بنك التفاضلي على مستوى الجلوكوزفي -التكاملي-تقنیة الخطوات التراجعیھ ھي التي استخدمت الضافة تأثیر المسیطر التناسبي. نسبة ضخ االنسولین والذي تعرض bergman نموذجاك عالقھ مباشرة بین المعامل المتغیر وھو ضخ االنسولین ونسبة الجلوكوز في الدم في بما انھ لیس ھن, الدم تقنیة الخطوات التراجعیھ ھي عادة موصى بھا لتحقیق االستقرار و السیطرة . اضطراب خارجيالختبار تحمل السكر الشفھي بتطبیق وجبة طعام ك قد اوضحت النتائج تصرف مقنع جدا الستجابة الجلوكوز الرتفاع مفاجئ ممثل بوجبة والتي .االنظمة الالخطیةمن bergmanعلى حاالت نمط .تسبب زیادة نسبة الجلوكوزفي الدم mailto:teeta.control@yahoo.com taghreed m. mohammad al-khwarizmi engineering journal, vol. 7, no. 4, pp 54 -60 (2011) 61 )2011( 5460 ، صفحة4 ، العدد7مجلة الخوارزمي الھندسیة المجلد تغرید محمد محمدرضا 60 يوسف خلف al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 8, no. 3, pp 1223(2012) experimental & theoretical analysis of composite (polyester & silicon-carbide) cantilever beam yousif k. yousif ministry of higher education and scientific research/ research & development department email: yousifky@gmail.com (received 2 april 2012; accepted 24 july 2012) abstract a cantilever beam is made from composite material which is consist of (matrix: polyester) and (particles: siliconcarbide) with different volume fraction of particles. a force is applied at the free end of beam with different values. the experimental maximum deflection of beam which occurs at the point of the applied load is recorded. the deflection and slope of beam are analyzed by using fem modeling. matlab paltform is built to assemble the equations, vector and matrix of fem and solving the unknown variables (deflection and slope) at each node. also ansys platform is used to modeling beam in finite element and solve the problem. the numerical methods are used to compare the results with the theoretical and experimental data. a good agreement is observed between the above methods. the increase in volume fraction of particles results in increasing the modulus of elasticity and decreasing the deflection of beam. an equation is suggested for modulus of elasticity as functions of volume fraction. keywords: composite beam, fem, polyester, silicon-carbide. 1. introduction structures composed of composite materials offer lower weight and higher strength and stiffness than those composed of most metallic materials. that, coupled with advances in the manufacturing of composite materials and structures, gave them an edge when compared with normal engineering materials and led to their extensive use under complex mechanical and environmental loading. these composite structures can be modeled as simply supported beam or clamped beams. presents numerical and experimental results of active compensation of thermal deformation of a composite beam using piezoelectric ceramic actuators finite-element modeling and experimental results agree well and demonstrate that the proposed method can actively perform structural shape control in the presence of thermal distortion [1]. an exact relationship between the slope increment of the beam end and the maximum slip at the support is presented, which makes possible an easy and accurate evaluation of the beam deflection increment. this relationship is alidated both by numerical and experimental results [2]. an efficient one dimensional finite element model has been presented for the static analysis of composite laminated beams, using the efficient layer wise zigzag theory. the present zigzag finite element results for natural frequencies, mode shapes of cantilever and clamped–clamped beams are compared with the two-dimensional finite element results obtained using abaqus to establish the accuracy of the zigzag theory fem for dynamic response under these boundary conditions [3]. investigated the effects of shear slip on the deformation of steel–concrete composite beams. the equivalent rigidity of composite beams considering three different loading types was first derived based on equilibrium and curvature compatibility, for full composite sections, the effective section modulus and moment of inertia calculated with the aisc specifications are larger than that of present study. for partial composite mailto:yousifky@gmail.com yousif k. yousif al-khwarizmi engineering journal, vol. 8, no.3, pp 1223(2012) 14 sections, the aisc predictions are more conservative than the present study [4]. investigate the structural behavior of concreteencased composite beam–columns with t-shaped steel section. the test results indicate that the cyclic behavior and failure modes of the beam– columns are greatly affected by the direction of the bending moment owing to the unsymmetrical cross section. [5] reviews the available literature on the state of the art of prefabricated wood composite i-beams. the results of analytical and experimental investigations illustrate the effects of materials, joint, geometry, and environment on the short and long-term performance of i-beams.[6] 2. experimental work 2.1. composite material the material used in this work is made from composite material including: • matrix: polyester. • particle: powder of silicon-carbide a homogenous mixing of powder with the polyester is done with the following particles volume fraction: table 1, volume fraction of silicon-carbide particles. vp % 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 each volume fraction gives new composite mechanical properties as comparing with the matrix or particle. the important property of composite material here is the modulus of elasticity (e). the value of (e) depends on volume fraction, modulus of elasticity for each matrix and particle material and given by the following equation [7]: e=vmem+ vpep … (1) where: e: modulus of elasticity of composite material (n/mm2) vm: matrix volume fraction vp: particle volume fraction em: matrix modulus of elasticity (2000n/mm2) ep: particle modulus of elasticity (4*105n/mm2) to calculate the modulus of elasticity (e) for the composite material, sub the above value of (em,ep) and the values of (vm,vp) from table (1) in the above equation(1). the results values of (e) are given in table (2). table 2, modulus of elasticity for each volume fraction. vp % e(n/mm2) 0.1 2398 0.2 2796 0.3 3194 0.4 3592 0.5 3990 0.6 4388 0.7 4786 0.8 5184 0.9 5582 1 5980 2.2. beam preparation and boundary conditions the sample of beam is made from composite material consist of (matrix: polyester) and (particle: silicon carbide). the beam sample is made with different volume fraction as mentioned. the geometry of beam is shown in fig. (1) : fig. 1. cantilever beam with free end load. *rectangular cross sectional area with: width: b= 13 mm. height: h= 6 mm. *length: l= 191 mm. a concentrated load is applied at the free end of beam length (x=l) to give a maximum deflection at this point. the state of boundary conditions for cantilever beam is given as follow: deflection & slope=0 at (x=0). the values of forces used in this work are given in table (3). table 3, the values of load used. p(n) 0.981 1.962 2.943 3.924 4.905 5.886 yousif k. yousif al-khwarizmi engineering journal, vol. 8, no.3, pp 1223(2012) 15 3. theoretical analysis the deflection of concentrated force beam (fig.(1)) given in the following equation[8]: ei lpx ei pxy 26 23 −== δ …(2) hence, the maximum deflection occurred at the free end(x=l): ei pl 3 3 =δ …(3) differentiate eq.(2) to give the slope of beam (θ=dy/dx): ei pxl ei pxdxdy −== 2 / 2 θ …(4) where: i: moment of inertia. its equation in this work is: 12 3bhi = …(5) the beam dimensions (b=13 mm; h=6 mm), therefore, the value of i is: i= 234mm4. 4. finite element method the analysis of finite element equations is based on the euler-bernoulli equation for beam bending [9, 10, and 11]: ),()( 2 2 2 2 2 2 txq x vei xt v = ∂ ∂ ∂ ∂ + ∂ ∂ ρ …(6) where: v(x,t): transverse displacement of the beam. ρ: mass density per volume. ei: beam rigidity. q(x,t): external applied pressure loading. t,x :time and spatial axis along the beam axis. applying one of the methods of weighted residual, galerkin’s method, to the beam equation (eq.(6)) to develop the finite element formulation and the corresponding matrix equations. the weight residual of eq.(6) is : ∫ =− ∂ ∂ ∂ ∂ + ∂ ∂l wdxq x vei xt v 0 2 2 2 2 2 2 0))((ρ …(7) where: l: length of beam. w: a test function. describe the beam in to a number of finite element, integrate eq.(7) by parts twice for the second term gives: ∫ ∫ ∫ ∑ = ∂ ∂ −+− ∂ ∂∂ + ∂ ∂ = = e e eω ω l 0m ω 2 22 2 2 n 1i 0] x wm[vq]wdxqdx x wveiwdx t vρ [ii …(8) where: .: .: .: .: 2 2 3 3 beamforelementsofnumbern domainelementan momentbending x veim forceshear x veiv e m ω ∂ ∂ = ∂ ∂ = the shape function is considered in term of nodal variable. assume beam element have two nodes one at each end as shown in fig. (2). fig. 2. deflection and slope of each node in element. the deformation of beam must have continuous slope as well as continuous deflection at any neighboring beam elements (slope: θi, deflection: vi), as nodal variables. the eulerbernoulli equation for beam bending is based on the assumption that the plane normal to the neutral axis before deformation remains normal to the neutral axis after deformation. the deflection equation is assumed as a cubic polynomial: 3 3 2 21)( xcxcxccxv o +++= ...(9) the slope can be found by differentiate eq.(9) w.r.t. x as follow: 2 321 32)( xcxccx ++=θ …(10) the deflection and slope at each node yield: yousif k. yousif al-khwarizmi engineering journal, vol. 8, no.3, pp 1223(2012) 16 2 2 321 3 3 2 21 11 1 32)( )( )0( )0( θθ θθ =++= =+++= == == lclccl vlclclcclv c vcv o o …(11) solving eq.(11) for ci in term of nodal variable (deflection and slope) and substituting the results into eq.(9) gives: 24 231211 )( )()()()( θ θ xh vxhxhvxhxv + ++= …(12) where: 2 32 4 3 3 2 2 3 2 32 2 3 3 2 2 1 )( 23)( 2)( 231)( l x l xxh l x l xxh l x l xxxh l x l xxh +−= −= +−= +−= …(13) the function hi are called hermitian shape function. application of this function and galerkin’s method to the second term of eq.(8) results in the stiffness matrix of the beam element. that is : ∫= l te dxbeibk 0 ][][][ …(14) where: },,,{][ 4 '' 3 '' 2 '' 1 '' hhhhb = …(15) the corresponding element nodal degrees of freedom are: }{}{ 2211 θθ vvd e = …(16) differentiate the shape function twice and sub the results in eq.(15) which can be sub in eq.(14) to find the integration results of the element stiffness matrix as follows:             − −−− − − = 22 22 3 4626 612612 2646 612612 ][ llll ll llll ll l eike …(17) the third term of eq.(8) represented as a concentrated load in this work, fig. (3), the element force vector is :               =               −=∫ )( )( )( )( )(}{ 04 03 02 01 0 4 3 2 1 xh xh xh xh pdx h h h h xxpf o l oo e δ …(18) where: po: the concentrated load applied at x=xo. δ(x=xo) : dirac dilta function. fig. 3. the location of concentrated load in element. for the static bending analysis of beams, the first term of eq.(8) which is the inertia force is neglected. the last term in the same above equation is the boundary conditions of shear and bending moment at the two points (x=0 & x=l). only a concentrated force is used at the free end of beam, therefore, the last term of eq.(8) will neglect. assembling the element stiffness matrices and vector results in the system matrix equation given below: }{}]{[ fdk = …(19) 4.1. finite element programming the finite element method [12] has been done using a matlab platform. the steps of this platform are shown in fig. (4) and explained as follows: step (1): in this step, it assumed that the number of element used is five with (6 nodes). each node has two degree of freedom. step (2): material properties represented by input the modulus of elasticity for each value of volume fraction which is described in table (2) of the experimental work. input the beam dimensions included the width, height and its length. step (3): in finite element analyzing, it assume a half beam due to symmetry; therefore the boundary conditions will be: at the fixd end (x=0, deflection=0, slope=0). yousif k. yousif al-khwarizmi engineering journal, vol. 8, no.3, pp 1223(2012) 17 step (4):the applied load will concentrate at the free end of beam and its value be (f). step (5): element stiffness can be evaluated from eq.(17). step (6): global element stiffness has been evaluated for the half beam as matrix of dimension (12*12). step (7): solve eq.(19) to give the deflection and slope at each node. fig. 4. steps of finite element method. 5. beam modeling in ansys platform ansys 11 platform is used to analyze the deflection and slope of beam which is defined by ten elements (11 nodes) as shown in fig. (5). the material property (e), beam dimensions (b,h,l) and boundary conditions is given as input data from the experimental work. also the concentrated load is applied at the free end of beam length (node 11: x=l). fig. 5. element and node numbering of beam in ansys platform. 6. the result the experimental results are plotted in figures (6-15) for wide range of concentrated force. each figure represent the variation of maximum beam deflection (at x=l) with the applied concentrated load at the same point for each volume fraction mentioned in the experimental work. theoretical, finite element method and the analyzing of beam deflection using ansys paltform are used here to compare the result data of those methods with the experimental data. basically, increasing the concentrated load results in increasing the deflection of beam. the models of fem and ansys platform for analysis the deflection of beam gives a good agreement with the theoretical analysis as well as with the experimental data. in general, the relation between the applied load and the deflection has a linear function. as it has been observed, the experimental data are alternate about the theoretical, fem and ansys results with small error. a scatter experimental data are observed which may be due to the mistake recording of equipment. variation of maximum deflection with volume fraction for each load is shown in figure (16). increasing the volume fraction of silicon-carbide particles results in decreasing the deflection with a smooth curve . this is due to increasing the modulus of elasticity of composite material with increasing the volume fraction of particles as in table (2). yousif k. yousif al-khwarizmi engineering journal, vol. 8, no.3, pp 1223(2012) 18 fem and ansys platform gives the deflection for each point of beam as well as the slope of beam at each point. a sample results is choose for the applied load (p=5.886 n) and volume fraction (vp=0.1%) shown in figure (17). a good agreement is observed as comparing the numerical method with the theoretical equation. the deformed shape resulted from the ansys platform for the same above force and volume fraction is shown in figures (18 & 19) for deflection and slope results respectively. on the other hand another suggested equation can be found for the modulus of elasticity for composite material of this work as a function of volume fraction of particle. figure (20) show the graph of modulus of elasticity with particle volume fraction. the linear equation can be represented as follow: e(vp) = 2000 + 398000 * vp … (20) where (em=2000 gpa), the above equation can be written in another form as follow: e(vp)=em+398000*vp …(21) 0 2 4 6 force (n) 0.0 5.0 10.0 15.0 20.0 25.0 m ax im um d ef le ct io n (m m ) theoretical fem ansys experimental fig. 6. variation of deflection with the applied force (vp=0.2%). 0 2 4 6 force (n) 0.0 5.0 10.0 15.0 20.0 25.0 m ax im um d ef le ct io n (m m ) theoretical fem ansys experimental fig. 7. variation of deflection with the applied force (vp=0.1%). 0 2 4 6 force (n) 0.0 4.0 8.0 12.0 16.0 20.0 m ax im um d ef le ct io n (m m ) theoretical fem ansys experimental fig. 8. variation of deflection with the applied force (vp=0.3%). yousif k. yousif al-khwarizmi engineering journal, vol. 8, no.3, pp 1223(2012) 19 0 2 4 6 force (n) 0.0 4.0 8.0 12.0 16.0 20.0 m ax im um d ef le ct io n (m m ) theoretical fem ansys experimental fig. 9. variation of deflection with the applied force (vp=0.4%). 0 2 4 6 force (n) 0.0 4.0 8.0 12.0 16.0 m ax im um d ef le ct io n (m m ) theoretical fem ansys experimental fig. 10. variation of deflection with the applied force (vp=0.5%). 0 2 4 6 force (n) 0.0 4.0 8.0 12.0 16.0 m ax im um d ef le ct io n (m m ) theoretical fem ansys experimental fig. 11. variation of deflection with the applied force (vp=0.6%). 0 2 4 6 force (n) 0.0 4.0 8.0 12.0 16.0 m ax im um d ef le ct io n (m m ) theoretical fem ansys experimental fig. 12. variation of deflection with the applied force (vp=0.7%). yousif k. yousif al-khwarizmi engineering journal, vol. 8, no.3, pp 1223(2012) 20 0 2 4 6 force (n) 0.0 4.0 8.0 12.0 m ax im um d ef le ct io n (m m ) theoretical fem ansys experimental fig. 13. variation of deflection with the applied force (vp=0.8%). 0 2 4 6 force (n) 0.0 4.0 8.0 12.0 m ax im um d ef le ct io n (m m ) theoretical fem ansys experimental fig. 14. variation of deflection with the applied force (vp=0.9%). 0 2 4 6 force (n) 0.0 2.0 4.0 6.0 8.0 10.0 m ax im um d ef le ct io n (m m ) theoretical fem ansys experimental fig. 15. variation of deflection with the applied force (vp=1%). 0.0 0.4 0.8 1.2 volume fraction vp % 0.0 5.0 10.0 15.0 20.0 25.0 m ax im um d ef le ct io n (m m ) f=0.981 n f=1.962 n f=2.943 n f=3.924 n f=4.905 n f=5.886 n fig. 16. variation of deflection with the volume fraction . yousif k. yousif al-khwarizmi engineering journal, vol. 8, no.3, pp 1223(2012) 21 0 40 80 120 160 200 the distance (x,mm) 0e+0 4e-2 8e-2 1e-1 2e-1 2e-1 sl op e dy /d x theoretical fem ansys fig. 17. variation of slope with the distance (x). fig. 18. variation of deflection along beam length for (p=5.886 n) and (vp=0.1%), ansys platform. fig. 19. variation of slope along beam length for (p=5.886 n) and (vp=0.1%), ansys platform. 0.0 0.4 0.8 1.2 volume fraction vp % 2000 3000 4000 5000 6000 m od ul us o f e la st ic ity (e ) , m p a. fig. 20. variation of (e) with volume fraction. yousif k. yousif al-khwarizmi engineering journal, vol. 8, no.3, pp 1223(2012) 22 7. conclusions the theoretical fem analysis for the deflection of beam gives a good agreement with the experimental results. experimental increasing the volume fraction of siliconcarbide particles, decreasing the deflection of beam for the same applied force & increasing the modulus of elasticity of composite material with increasing the volume fraction of particles. theoretical the slope calculated from the fem and ansys program gives a good agreement comparing with the theoretical equation. the relation between the deflection reduction and the volume fraction is suggested as a polynomial third order equation. a linear equation for the modulus of elasticity for the composite material as a function of volume fraction and matrix modulus of elasticity is observed and the fitting of this equation is suggested. 8. references [1] g. song1, x. zhou and w. binienda “thermal deformation compensation of a composite beam using piezoelectric actuators” smart materials and structure, institute of physics publishing, smart mater. struct. 13 (2004) 30–37 . [2] p. gelfi and e. giuriani “influence of slabbeam slip on the deflection of composite beams” international journal for restoration of buildings and monuments vol. 9, no 5, 475–490 (2003) [3] m. naushad alam and nirbhay kr. upadhyay “finite element analysis of laminated composite beams for zigzag theory using matlab” international journal of mechanics and solids , issn 0973-1881 volume 5, number 1 (2010), pp. 1-14 [4] jianguo nie1 and c. s. cai, p.e., m.asce “steel–concrete composite beams considering shear slip effects”, journal of structures engineering asce / april 2003. [5] cheng-chih chen, jian-ming li, c.c. weng , “experimental behavior and strength of concrete-encased composite beam–columns with t-shaped steel section under cyclic loading”, journal of constructional steel research 61 (2005) 863–881. [6] robert j. leichti , robert h. falk and theodore l. laufenberg “prefabricated wood composite i-beams: a literature review ” wood and fiber science, 2(1), 1990, pp. 6279. [7] autar k. kaw “ mechanics of composite materials” taylor & francis group, llc,2006. [8] lloyd hmilton donnell “beams, plates and shells” mcgraw-hill, inc. 1976. [9] o.c. zienkiewics, frs. “the finite element method” mc. graw hill book company (uk) limited 1977. [10] tirupathir. chandrupathla and ashok d.belegundu “finite element in engineering” prentice/hall of india,1977. [11] james doyle “finite element methods” john wiley & sons, ltd 2004. [12] hinton and d.r.j. owen. “ finite element programing” academic press inc. (london) ltd.1983. )2012( 23 -12، صفحة3، العدد8 مجلة الخوارزمي الھندسیة المجلد یوسف یوسف خلف 23 لعتبة مثبتة) السیلكون دالبولیستر ودقائق كاربی(التحلیل النظري والعملي للمادة المركبة یوسف خلف یوسف دائرة البحث والتطویر /وزارة التعلیم العالي والبحث العلمي yousifky@gmail.com : االلكتروني البرید ةالخالص ان القوى . بقیم مختلفة من الكسر ألحجمي) السیلكون -دالبولیستر ودقائق كاربی( وحرة من طرف اخر من المادة المركبة طرفتم تصنیع عتبة مثبتة من م تحلیلھ باستخدام طریقة انحراف ومیالن العتبة ت. قیم أقصى انحراف للعتبة و قرأت مختبریا عند نقطة تسلیط القوة. المسلطة عند النھایة الحرة للعتبة ) االنحراف والمیالن( وحل المتغیرات المجھولة matlabحیث تم تجمیع معادالت، متجھات ومصفوفة ھذه الطریقة باستخدام برنامج . العناصر المحددة ستخدمت لمقارنة النتائج مع النتائج النظریة الطرق العددیة ا. لتحلیل العتبة بطریقة العناصر المحددة) ansys( أیضا تم استخدام برنامج أل. عند كل عقدة .ان زیادة الكسر الحجمي للحبیبات أدى إلى زیادة معامل المرونة ونقصان انحراف العتبة. نتائج النظریة والعملیةالتمت مالحظة توافق جید بین تلك . والعملیة mailto:yousifky@gmail.com shear lag in partially simply composite steel-concrete beams al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 8, no. 2, pp 63 76 (2012) effect of stiffeners on shear lag in steel box girders mohannad h. m. al-sherrawi ghaidak ahmed fadhil department of civil engineering/ college of engineering/university of baghdad email: mhnd7@yahoo.com (received 14 july 2011; accepted 10 january 2012) abstract this paper studies the effects of stiffeners on shear lag in steel box girders with stiffened flanges. a threedimensional linear finite element analysis using staad.pro v8i program has been employed to evaluate and determine the actual top flange stress distribution and effective width in steel box girders. the steel plates of the flanges and webs have been modeled by four-node isoparametric shell elements, while the stiffeners have been modeled as beam elements. different numbers (4, 8, and 15) for the steel stiffeners have been used in this study to establish their effects on the shear lag and longitudinal stresses in the flange. using stiffeners reduced the magnitude of the top flange longitudinal stresses about 40%, but didn’t affect the shear lag. keywords: shear lag, effective width, box girder, stiffeners. 1. introduction a box girder is a beam which has the shape of a hollow box. the box girder normally comprises either structural steel, prestressed concrete, or a composite of steel and reinforced concrete. the box is typically rectangular or trapezoidal in cross-section. box girder bridges are commonly used for highway flyovers and for modern elevated structures of light rail transport. although normally the box girder bridge is a form of beam bridge, box girders may also be used on cable-stayed bridges and other forms. 1.1. advantages and disadvantages compared to i-beam girders, box girders have a number of key advantages and disadvantages. box girders offer better resistance to torsion, which is particularly of benefit if the bridge deck is curved in plan. additionally, larger girders can be constructed, because the presence of two webs allows wider and hence stronger flanges to be used. this in turn allows longer spans. on the other hand, box girders are more expensive to fabricate, and they are more difficult to maintain, because of the need for access to a confined space inside the box. 1.2. shear lag the conventional engineering theory of bending assumes that plane sections remain plane, which means that shearing strains are neglected. the term shear lag is used to describe the discrepancies between the approximate engineering theory, and the real behavior that results in both the increases in the stresses in the flange component adjacent to the web component in a steel box girder, and to the decreases in the stresses in the flange component away from the web. as shown in figure (1), the longitudinal stress  yx at the flange of a box section distributes uniformly with b along the y-axis based on the elementary beam theory. however, at the intersection of the flange and web where y = ±b, the actual maximum longitudinal stress )by(max,x  is higher than the average longitudinal stress of b . this high stress of the transfer of the shear force from the web to the mailto:mhnd77@yahoo.com http://en.wikipedia.org/wiki/bridge http://en.wikipedia.org/wiki/box_girder http://en.wikipedia.org/wiki/structural_steel http://en.wikipedia.org/wiki/prestressed_concrete http://en.wikipedia.org/wiki/composite_material http://en.wikipedia.org/wiki/reinforced_concrete http://en.wikipedia.org/wiki/rectangle http://en.wikipedia.org/wiki/trapezoid http://en.wikipedia.org/wiki/cross_section_(geometry) http://en.wikipedia.org/wiki/overpass http://en.wikipedia.org/wiki/light_rail http://en.wikipedia.org/wiki/beam_bridge http://en.wikipedia.org/wiki/cable-stayed_bridge http://en.wikipedia.org/wiki/i-beam http://en.wikipedia.org/wiki/torsion_(mechanics) http://en.wikipedia.org/wiki/flange http://en.wikipedia.org/wiki/span_(architecture) http://en.wikipedia.org/wiki/confined_space mohannad h. m. al-sherrawi al-khwarizmi engineering journal, vol. 8, no. 2, pp 63 -76 (2012) 64 flange edge is called the shear lag phenomenon (timoshenko and goodier 1970). in the analysis of any box girder, it is important to take the effects of shear lag into account since these effects can lead to a significant increase in the longitudinal stresses developed in the flanges. fig. 1. typical box section under bending (timoshenko and goodier, 1970) . 1.3. staad.pro v8i staad.pro v8i is a comprehensive and integrated finite element analysis and design offering, including a state-of-the-art user interface, visualization tools, and international design codes. it is capable of analyzing any structure exposed to static loading, a dynamic response, soil-structure interaction, wind, earthquake, and moving loads. staad.pro v8i is the premier finite element method analysis and design tool for any type of project including towers, culverts, plants, bridges, stadiums, and marine structures 2. review of the previous studies shear lag has long been of interest to researches. firstly, shear lag in box girders was studied by reisser (1946). malcolm and redwood (1970) suggested analytical procedure using stiffener-sheet solution. moffatt and dowling (1975) studied the shear lag phenomenon in steel box girder bridges by means of the finite element method of analysis. kuzmanovic’ and graham (1981) found the minimum potential energy principle which was a suitable approach to evaluate the shear lag in box girders. foutch and chang (1982) investigated the effects of shear lag and shear deformation on the static and dynamic response of tapered thin-walled box beams. dezi and mentrasti (1985) discussed nonuniform normal longitudinal stress distribution (shear lag) in a trapezoidal box beam with lateral cantilever. chang and zheng (1987) analyzed shear lag and negative shear lag effect in cantilever box girders through variation approach and finite element techniques. the substructuring analysis method for shear lag stress using the conditions of compatibility and equilibrium was introduced by fafitis and rong (1996) lee and wu (2000) improved the inefficiency of traditional finite element analysis using uniform meshes in the solution of shear lag stress. wang (1997) derived an energy equation for the lateral buckling of thinwalled members with openings considering shear lag phenomenon. also, luo et al. (2001) studied the negative shear lag in box girder with varying depth. however, these studies recognized that the complicated equations are not so practical for the design of steel box girders. luo et al. (2002) carried out experimental study on the shear lag effect of box girder with varying depth. hwang et al. (2004) presented shear lag parameters for beam-to-column connections in steel box piers. zhibin lin and jian zhao (2010) used an energybased variation analysis to evaluate the aashto provisions for effective flange width. 2.1. shear lag in box beam under symmetrical flexure, the distributions of bending stress across wide flanges of a girder cross section are non-uniform. the bending stress near the web is much larger than that far from the web, as shown in figure (2-a). this phenomenon is usually noted as positive shear lag (chang and zhang, 1987). in a cantilever box girder with constant depth, under uniform load, at the region beyond 1/4 the cantilever length from the built-in end, the bending stress near the web is much smaller than that far from the web. this result is opposite to positive shear lag and is called negative shear lag as shown in figure (2-b) (chang and zhang, 1987). mohannad h. m. al-sherrawi al-khwarizmi engineering journal, vol. 8, no. 2, pp 63 -76 (2012) 65 fig. 2. shear lag effecta) positive shear lag, b) negative shear lag (chang and zhang, 1987). 2.2. effective flange width the effective width of a flange is the width of a hypothetical flange that compresses uniformly across its width by the same amount as the loaded edge of the real flange under the same edge shear forces. alternatively, the effective width can be thought of as the width of theoretical flange which carries a compression force with uniform stress of magnitude equal to the peak stress at the edge of the prototype wide flange when carrying the same total compression force (hamply, 1976). the effective width concept has been widely recognized and implemented into different codes of practice around the world. the effective width of a girder flange varies along the span and depends significantly on the load distribution, cross-sectional properties, and boundary conditions, as well as the plan dimensional of the girder (moffatt and dowling, 1975). effective width may be defined in a variety of ways depending on which design parameter is deemed more significant. it is generally obtained by integrating the rigorously calculated longitudinal stress in the flange, and dividing by the peak value of stress. and therefore b is calculated here by considering flange stress and is given by:   .max 0 x b x dy b    …(1) where _ b is one-side effective flange width, b is half flange width, σx represent the normal stress in the longitudinal direction, and (σx)max. is the maximum normal stress between 0 ≤ y ≤ b. in this work, the numerator of equation (1) was calculated by the approximate method by using trapezoidal rule; these calculations have been done by a computer program written for that purpose. the main aim of the present study is to investigate the effect of the stiffeners on the top flange longitudinal stress distribution and effective width in steel box girders by using finite element method to idealize the steel box girder. 3. finite element modeling staad.pro 2007 program was used to create three dimensional finite element model of the steel box girder. three-dimensional four-node isoparametric shell elements were used to model the steel plates, while the stiffeners were modeled by beam elements. the steel model used for all components in the girder model was linear/elastic, the elastic modulus used was 29,000 ksi and the poisson’s ratio was 0.3 (astm a36). the steel box girder used as a reference throughout this paper is based on the cross-section shown in figure (3). the simply supported girder has a width that equals 144 in., a depth that equals 72 in., and a length that equals 720 in. the thickness of the steel plates equals 0.5 in. the stiffeners of each flange is 4.5 in. 1 in. @ 9 in. c/c (total = 15). same stiffeners wear used for top and bottom flanges to fix the distance between the neutral axis and the top flange as the stiffener ratio changed. fig. 3. cross section of the reference steel box girder . 144 in. 7 2 i n . theoryelementary effect lagshear (a) (b) mohannad h. m. al-sherrawi al-khwarizmi engineering journal, vol. 8, no. 2, pp 63 -76 (2012) 66 the three-dimensional finite element mesh for the reference steel box girder used in staad.pro v8i program is shown in figure (4). fig. 4. three-dimensional finite. 4. parametric study ` in this section, influence of various parameters on top flange stress distribution and effective width in steel box girders were investigated. the parameters studied can be summarized as follows: 1. stiffener ratio (area of stiffeners/area of top flange). 2. distribution of stiffeners. 3. type of loading. 4. depth/width of the section. 5. length of girder. in this work, two types of loading are investigated, the magnitude of the two loads was selected to give equal deflection at the mid-span, and these two cases will be referred to in the following as: a. uniformly distributed load (udl) (150 kips) (on the overall flange). b. two concentrated loads (cl) (247 kips) at midspan (one on each web). the maximum top flange stresses (over the web) for different stiffener ratios with respect to the two types of loading (udl and cl) are listed in table (1), and the distributions of the top flange stresses are shown in figures (5 and 6) respectively. each set of lines represent the edge of the effective width for one web. adding stiffeners with area that equals the flange area decreases the maximum top flange stress in about 40%. the effective flange widths for different stiffener ratios with respect to the two types of loading are shown in table (2), and the distribution of the effective flange widths is shown in figures (7 and 8) respectively. it can be seen from the results obtained that:  the top flange longitudinal stresses decrease as the stiffener ratio increases. the decreasing ranged between 18% and 40%. this is due to the share of the stiffeners in the forces makes the stresses in the flange decrease.  the maximum top flange longitudinal stress over each web decreases as the stiffener ratio increases. the decreasing reached 40%.  the addition of stiffeners to the flanges results no effect on shear lag because the shear lag phenomenon does not affect the shape of the flange.  the effective width decreases slightly as the stiffener ratio increases (5% in case of udl and 13% in case of cl). table 1, maximum top flange stresses for different stiffener ratios with respect to the two types of loading (udl and cl). stiffener ratios maximum top flange stress udl cl beam length percentage beam length percentage 0.1 l 0.2 l 0.3 l 0.4 l 0.5 l 0.1 l 0.2 l 0.3 l 0.4 l 0.5 l 0.0 1067 1551 1964 2234 2328 664 1109 1627 2211 3356 0.5 880 1190 1464 1653 1719 521 813 1178 1625 2642 1.0 780 999 1195 1334 1385 436 646 930 1302 2239 mohannad h. m. al-sherrawi al-khwarizmi engineering journal, vol. 8, no. 2, pp 63 -76 (2012) 67 table 2, effective flange widths for different stiffener ratios with respect to the two types of loading. stiffener ratios effective flange width udl cl beam length percentage beam length percentage 0.1 l 0.2 l 0.3 l 0.4 l 0.5 l 0.1 l 0.2 l 0.3 l 0.4 l 0.5 l 0.0 93 127 135 136 136 104 139 143 140 111 0.5 80 119 129 132 133 92 134 140 135 103 1.0 73 113 125 128 129 86 131 138 132 96 another parameter, investigated is changing the number (4, 8, and 15) of the stiffeners with keeping the same area of the stiffeners. effect of distribution of stiffeners on maximum top flange stress and the effective flange widths are listed in table (3). figures (9 and 10) show the distribution of the top flange stress and the effective flange respectively. the results declare that there are no effects because the stiffeners have the same area in all three cases. table 3, effect of distribution of stiffeners on maximum top flange stress and the effective flange widths. number of stiffeners maximum top flange stress effective flange width beam length percentage beam length percentage 0.1 l 0.2 l 0.3 l 0.4 l 0.5 l 0.1 l 0.2 l 0.3 l 0.4 l 0.5 l 4 797 1022 1220 1361 1411 72 115 126 129 130 8 784 1005 1202 1339 1389 73 113 125 129 130 15 781 999 1195 1335 1385 73 113 125 128 129 table (4) shows the maximum top flange stresses and effective flange widths according to type of loading. the distribution of longitudinal normal stresses in the top flange has different shapes along the flange according to type of loading as shown in figure (11). the distribution of the effective flange widths which is due to type of loading is shown in figure (12). table 4, maximum top flange stresses and effective flange widths according to type of loading. type of loading maximum top flange stress effective flange width beam length percentage beam length percentage 0.1 l 0.2 l 0.3 l 0.4 l 0.5 l 0.1 l 0.2 l 0.3 l 0.4 l 0.5 l udl 781 999 1195 1335 1385 73 113 125 128 129 cl 436 647 930 1302 2240 86 131 138 132 95 effect of the ratio depth/width on the maximum top flange stresses and the effective flange widths is listed in table (5), and the effect on the top flange stresses distribution and the effective flange widths distribution for different ratios is shown in figures (13 and 14) respectively. mohannad h. m. al-sherrawi al-khwarizmi engineering journal, vol. 8, no. 2, pp 63 -76 (2012) 68 table 5, effect of the ratio of depth/width on maximum top flange stresses and effective flange widths. depth/width maximum top flange stress effective flange width beam length percentage beam length percentage 0.1 l 0.2 l 0.3 l 0.4 l 0.5 l 0.1 l 0.2 l 0.3 l 0.4 l 0.5 l 0.5 781 999 1195 1335 1385 73 113 125 128 129 1.0 151 420 541 606 630 116 111 122 127 128 table (6) shows the effect of length of girder on the maximum top flange stresses and effective flange widths and figure (15 and 16) show the top flange stress distribution and the distribution of the effective flange widths for different lengths of the girder. table 6, effect of length of girder on maximum top flange stresses and effective flange widths. length of girder maximum top flange stress effective flange width beam length percentage beam length percentage 0.1 l 0.2 l 0.3 l 0.4 l 0.5 l 0.1 l 0.2 l 0.3 l 0.4 l 0.5 l 37.5 333 560 603 636 651 52 78 98 107 110 60.0 781 999 1195 1335 1385 73 113 125 128 129 82.5 1203 1667 2112 2392 2487 96 128 134 135 136 105.0 1676 2579 3330 3787 3940 114 135 137 138 139 (a) (b) (a) (b) mohannad h. m. al-sherrawi al-khwarizmi engineering journal, vol. 8, no. 2, pp 63 -76 (2012) 69 fig. 5. effect of stiffener ratio on top flange stress distribution (udl). (a) at 0.1 l (b) at 0.2 l (c) at 0.3 l (d) at 0.4 l (e) at 0.5 l. fig. 6. effect of stiffener ratio on top flange stress distribution (cl). (a) at 0.1 l (b) at 0.2 l (c) at 0.3 l (d) at 0.4 l (e) at 0.5 l (c) (d) (e) (c) (d) (e) mohannad h. m. al-sherrawi al-khwarizmi engineering journal, vol. 8, no. 2, pp 63 -76 (2012) 70 fig. 7. effect of stiffener ratio on the distribution of the effective flange widths (udl). ℄ effective width for single web fig. 8. effect of stiffener ratio on the distribution of the effective flange widths (cl). ℄ effective width for single web mohannad h. m. al-sherrawi al-khwarizmi engineering journal, vol. 8, no. 2, pp 63 -76 (2012) 71 fig. 9.effect of distribution of stiffeners on top flange stress distribution . (a) at 0.1 l (b) at 0.2 l (c) at 0.3 l (d) at 0.4 l (e) at 0.5 l. (a) (b) (c) (d) (e) fig. 10. effect of distribution of stiffeners on the distribution of the effective flange widths. ℄ effective width for single web mohannad h. m. al-sherrawi al-khwarizmi engineering journal, vol. 8, no. 2, pp 63 -76 (2012) 72 fig. 11. effect of loading on top flange stress distribution. (a) at 0.1 l (b) at 0.2 l (c) at 0.3 l (d) at 0.4 l (e) at 0.5 l. (a) (b) (c) (d) (e) fig. 12. effect of loading on the distribution of the effective flange widths . ℄ effective width for single web mohannad h. m. al-sherrawi al-khwarizmi engineering journal, vol. 8, no. 2, pp 63 -76 (2012) 73 fig. 13. effect of depth/width on top flange stress distribution. (a) at 0.1 l (b) at 0.2 l (c) at 0.3 l (d) at 0.4 l (e) at 0.5 l. (a) (b) (c) (d) (e) fig. 14.effect of depth/width on the distribution of the effective flange widths. ℄ effective width for single web mohannad h. m. al-sherrawi al-khwarizmi engineering journal, vol. 8, no. 2, pp 63 -76 (2012) 74 fig. 15. effect of length of girder on top flange stress distribution. (a) at 0.1 l (b) at 0.2 l (c) at 0.3 l (d) at 0.4 l (e) at 0.5 l. (a) (b) (c) (d) (e) fig. 16. effect of length of girder on the distribution of the effective flange widths. ℄ effective width for single web mohannad h. m. al-sherrawi al-khwarizmi engineering journal, vol. 8, no. 2, pp 63 -76 (2012) 75 5. conclusions 1. using the longitudinal stiffeners in the flanges of steel box girder did not affect the shear lag in the top flange, although it reduced the magnitude of the top flange longitudinal stresses to about 40%, and decreases slightly the effective width (5%-13%) because portion of these stresses go to the stiffeners. 2. increasing the stiffener ratio make the top flange longitudinal stresses decrease. 3. changing the number (4, 8, and 15) of the stiffeners with keeping the same area of the stiffeners has no effects on the magnitude of the top flange longitudinal stresses due to using the same area of the stiffeners. notations b one-side slab width b one-side effective slab width es modulus of elasticity of steel l span length of the beam ν poisson's ratio x normal stress in the longitudinal direction .maxx )( maximum normal stress in the longitudinal direction 6. references [1] chang, s. t., and zheng, f. z. (1987) "negative shear lag in cantilever box girder with constant depth." journal of the structural engineering, vol. 113, no. 1, january, pp. 20-35. [2] dezi, l., and mentrasti, l. (1985) "nonuniform bending-stress distribution (shear lag)," journal of the structural engineering, vol. 111, no. 12, pp. 2675-2690. [3] fafitis, a. and rong, a. y. (1995), “analysis of thin-walled box girders by parallel processing”, thin-walled struct., 21, 233240. [4] foutch, d. a., and chang, p. c. (1982) "a shear lag anomaly," journal of the structural engineering, vol. 108, no. 7, pp. 1653-1658. [5] hamply, e. c., (1976) bridge deck behavior, chapman and hall, london ec4p 4ee, pp. 272. [6] hwang, w. s., kim, y. p., and park, y. m. “evaluation of shear lag parameters for beam-to-column connections in steel piers” structural engineering and mechanics, vol. 17, no. 5 (2004) 691-706. [7] kuzmanovi , b. o. and graham, h. j. (1981), “shear lag in box girder”, j. struct. div., asce, 107(9), 1701-1742. [8] lee, c. k. and wu, g. j. (2000), “shear lag analysis by the adaptive finite element method-1. analysis of simple plated structures”, thin-walled struct., 38, 285-309. [9] luo, q. z., tang, j., and li, q. z. (2001) “negative shear lag effect in box girders with varying depth,” journal of structural engineering, asce, , vol. 127, no. 10, pp. 1236-1239. [10] luo, q. z., tang, j. and li, q. s. (2002), “experimental studies on shear lag of box girder”, eng. struct., 24, 464-477. [11] malcolm, d. j. and redwood, r. g. (1970), “shear lag in stiffened box girders”, j. struct. div., asce, 96 (st7), 1403-1449. [12] moffatt, k. r., and dowling, p. j. (1975) "shear lag in steel box girder bridges," the structural engineer, vol. 53, no. 10, october, pp. 439-448. [13] reissner, e. (1946), “analysis of shear lag in box beams by the principle minimum potential energy”, quarterly app. math., 3 (3), 268-278. [14] timoshenko, s. p., and goodier, j. n. (1970) “theory of elasticity.” third edition, mc graw-hill, new york, pp. 567. [15] wang, q. f. (1997), “lateral buckling of thin-walled members with openings considering shear lag”, structural engineering and mechanics, 5 (4), 369-383. [16] zhibin lin, a. m. and jian zhao, a. m. “a revisit of aashto effective flange width provisions for box girders” journal of bridge engineering / accepted manuscripts in 2010. http://ascelibrary.org/beo/ http://ascelibrary.org/beo/ http://ascelibrary.org/beo/ http://ascelibrary.org/beo/resource/3/jbenxx http://ascelibrary.org/beo/resource/3/jbenxx http://ascelibrary.org/beo/resource/3/jbenxx (2012)63 76 ، صفحة2، العذد 8 مجلة الخىارزمً الهنذسٍة المجلذمهنذ حسٍن محسن 76 تأثٍر المقىٌات على تخلف القص فً األعتاب الصنذوقٍة الحذٌذٌة مهنذ حسٍن محسن الشراوي غٍذق أحمذ فاضل جايعت بغذاد / كهيت انُٓذست / قسى انُٓذست انًذَيت mhnd7@yahoo.com: انبشيذ االنكتشَٔي الخالصة أعتًذ انتحهيم بئستعًال طشيقت انعُاصش . ْزا انبحث يٕثق دساست تأثيش انًقٕياث عهى تخهف انقص في األعتاب انصُذٔقيت انحذيذيت راث انشفاِ انًقٕاة األعتاب في انعشض انفعالانًحذدة انخطيت ثالثيت األبعاد ٔبئستخذاو بشَايج ستاد بشٔ في انتحهيم ٔحساب انتٕصيع انحقيقي نإلجٓاداث في انشفت انعهيا ٔ بعُاصش أحاديت انبعذ راث سباعيت انعقذ ، بيًُا تى تًثيم انًقٕياث قششيت تى تًثيم انصفائح انحذيذيت نهشفتيٍ ٔانٕتشتيٍ بئستعًال عُاصش . انصُذٔقيت انحذيذيت إٌ . تى إستخذايٓا في ْزِ انذساست نًعشفت تأثيشْا عهى تخهف انقص ٔاإلجٓاداث باإلتجاِ انطٕني في انشفت (15 ، 8 ، 4)أعذاد يختهفت نهًقٕياث . عقذتيٍ . ، نكُّ ال يؤثش عهى تخهف انقص فيٓا% 40إستخذاو انًقٕياث يقهم يٍ قيًت اإلجٓاداث باإلتجاِ انطٕني في انشفت انعهيا بًقذاس يصم إنى mailto:mhnd7@yahoo.com mailto:mhnd7@yahoo.com محسن جبر al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 7, no.4, pp 17 -26 (2011) experimental estimation of critical buckling velocities for conservative pipes conveying fluid mohsen j.jweeg* albert e. yousif** mahmud r. ismail* * department of mechanical engineering/ university of al-nahrain ** department of medical engineering/ university of al-nahrain (received 23 may 2011; accepted 17august 2011) abstract conservative pipes conveying fluid such as pinned-pinned (p-p), clamped–pinned (c-p) pipes and clamped-clamped (c-c) lose their stability by buckling at certain critical fluid velocities. in order to experimentally evaluate these velocities, high flow-rate pumps that demand complicated fluid circuits must be used. this paper studies a new experimental approach based on estimating the critical velocities from the measurement of several fundamental natural frequencies .in this approach low flow-rate pumps and simple fluid circuit can be used. experiments were carried out on two pipe models at three different boundary conditions. the results showed that the present approach is more accurate for estimating the critical velocities of p-p and c-p pipes. however, for c-c pipes it was not so unless a higher flow rate is used. keywords: conservative pipes, critical buckling velocity. 1. introduction it has been demonstrated that the natural frequencies for conservative pipes conveying fluid such as pinned-pinned, clamped-pinned and clamped-clamped pipes decrease with the increasing of the fluid velocities [1] .at certain critical values of the fluid velocities the fundamental natural frequency can be dropped to zero .at this condition pipes can lose their stability by static divergence or buckling [2] and [3]. evaluating the critical velocities of buckling is an important task in pipes design .they separate the range of velocities at which the pipe becomes safe and stable from the unstable range. many early researchers studied the stability for conservative pipe conveying fluid like bishop and fawzy [4], gregory and paidoussis [5] and recently, kuiper and metrlkine [6] and wang and ni [7] .their investigations were focused on evaluating the critical fluid velocities for buckling instability and stability characteristics for pinnedpinned, clamped–pinned and clamped-clamped pipes conveying fluid. these studies were based on the solution of the equation of motion by either approximate analytical or numerical methods. long [8] carried out many experiments on pinned–pinned pipes to show the effect of the fluid velocity on the natural frequencies .benjamin [9] made a visual investigation for the dynamics of articulated pipes (two degree of freedom pipes) with different supports .many experiments measured the critical fluid velocities of buckling and recorded the flutter phenomena photographically. gregory and paidoussis [10] investigated experimentally the main dynamical features of the cantilever pipes such as the effects of fluid speed and mass ratio on flutter instability and the natural frequencies. critical velocities of buckling instability are normally high and it is difficult to measure them experimentally unless high flow rate pumps are used. as a result a complicated fluid circuit will result and the problem of turbulence may arise [11]. owing to these difficulties, a new approach is presented in the present work for evaluating the critical velocities of buckling from a set of experimental data .such data was obtained from mohsen j.jweeg al-khwarizmi engineering journal, vol. 7, no. 4, pp17-26 (2011) 18 measuring the fundamental natural frequencies at relatively low fluid velocities. 2. the present approach the relations between the fundamental natural frequencies and the fluid velocities for conservative pipes conveying fluid were derived by wang and his co-workers [12] in 2010. they gave the following expressions for the three conservative pipes conveying fluid: ei vm mm ei f fp 2 2 2 1. π πω − + = for(p-p) …(1) ei vm mm ei f fp 2 2 2 927.3 747.0 1.927.3 − + =ω for(c-p) …(2) ei vm mm ei f fp 2 2 2 73.4 55.0 1.73.4 − + =ω for(c-c) …(3) now, eqs.(1-3) may be written in the following dimensionless forms : ω = 2 2 2 1 π π u − …(4) ω = 2 2 2 378.6 173.4 u − …(5) ω = 2 2 2 543.4 1927.3 u − …(6) where : u= eimvl f /. … (7) and ω=ω eimml pf /)(.2 + …(8) squaring and arranging eqs.(4-6) gives: = ω 4 2 π 2 2 1 π u − … (9) = ω 4 2 927.3 2 2 543.4 1 u − … (10) = ω 4 2 73.4 2 2 378.6 1 u − …(11) when ω=0, eqs .(9-11) give the theoretical critical velocities of buckling uc for the three types of the conservative pipes which are: uc= π,4.543 ,6.378 furthermore, when u=0 ,eqs .(9-11) give the dimensionless fundamental frequencies ωb of the corresponding beams which are: ωb=π2,(3.927)2,( 4.73)2 in this way eqs .(9-11) can be put in the following general form: = ω ω 2 2 b 2 2 1 cu u − …(12) or : ω2=ωb 2-(ωb/uc)2u2 …(13) noting that eq.(13) represents a straight line in ω2-u2 plain. according to eq.(13), when a set of fundamental frequencies at given fluid velocities are plotted ω2 against u2 ,the result is a straight line .from this line the value of the critical velocity can be calculated. this is the basic concept of the present approach. in summary, the critical velocities can be estimated from the measured data of the fundamental natural frequencies, for a given model by performing the following steps: 1measuring the fundamental natural frequencies at a range of fluid velocities. 2plotting the data in ω2against u2. 3fitting the data to a straight line and determining its equation. 4comparing the equation of the fitted line with eq.(13) to find the critical velocity uc this approach enables using any available fluid velocities, however, when the flow rate is relatively low (less that 30 l/min) the variation in the fundamental frequencies become insensitive for most models. 3. apparatus and test models table 1 shows the specifications of the two test models used in this work. mohsen j.jweeg al-khwarizmi engineering journal, vol. 7, no. 4, pp17-26 (2011) 19 table 1, specifications of the test pipe models [13]. model no. material do m t m l (m) ρ kg/m3 e gn/ m2 1 aluminum 0.01 0.001 1.25 2650 62 2 pvc 0.011 0.0011 1.25 1000 (at 30 co) 7.12 (at 30 co) the test rig consists of two main parts; the foundation and the two end supports. the foundation was constructed from brownwalnut wood and reinforced by 2 mm thickness steel plates. see fig .( 2) fig.1. schematic layout for the wooden test rig. fig.2. a photograph for the test rig. wood was chosen for the foundation since it has the following advantages over the metallic materials: 1it is simple to process. 2it has a higher structural damping making it a good vibration-absorber for undesired vibrations that can be transmitted from the test model supports. 3the ratio e/ρ of most woods is about 25 kn.m/g as compared with 26 kn.m/g for the most common metallic material [14] .thus their dynamical behavior are nearly similar. the two end supports were designed to fulfill the various requirements for pinned and clamped conditions. they consisted of two main parts; the cast iron base and the steel holders. for pin support, a ball-bearing assembly was used to insure zero moment and displacement see fig.(3). fig. 3. configuration of pinned support. for clamp support, steel clamps were provided to insure zero slope and displacement necessary for clamped end condition. the various boundary conditions for the three conservative pipes can be performed by using the proper supports selection. water was used as a flowing fluid .to measure the water velocity a flow meter was fitted at the inlet of the test model. the water circuit is shown in fig.(4). the main components of this circuit are the collecting tank (150 litters) ,centrifugal pump (60 l/min,20 m ), control valve (gate type) and the test pipe model. mohsen j.jweeg al-khwarizmi engineering journal, vol. 7, no. 4, pp17-26 (2011) 20 in the case of pvc pipe models a digital thermometer was used to record the operating temperature since their mechanical properties are temperature dependant .the sensor of the thermometer was fitted on to the pipe outer surface. fig. 4.schematic diagram for test model and water circuit. the block diagram of the various components of the electric vibration circuit used in this work are shown in fig.(5). fig.5.block diagram for vibration circuit (the dash lines are for calibration mode). prior to testing, the densities and modulus of elasticity of the test models were checked and the accuracy of the instruments were tested. to check the modulus of elasticity for the test pipe models simple experiments were carried out. in these experiments the lowest three natural frequencies of the pipe models without fluid and under clamped –clamped conditions were measured .then the modulus of elasticity is calculated from the following formula: e= 2 24 n p ib lm ω for n=1, 2, 3 … (14) where: bn =1.5π, 2.5π, 3.5π the densities of the model materials were a checked by weighting pipe samples of length of 2cm by using a three-digit electronic balancer. the results showed good agreement between the measured and the calculated values. the accuracy of the flow meter was tested in a calibration process .in this test the water was allowed to full a reservoir of five liters capacity through the meter. the average time required for this process was recorded and the flow rate was calculated .the calculated flow rate was compared with the meter reading. the results gave good agreement. calibrating the variation of the vibration instruments focus was made on checking the overall accuracy due to measuring the frequency which is the main interest in this work. the accuracy of the amplitude was not taken into account .this is true since the natural frequencies can be measured by observing the resonance frequencies rather than their amplitudes. for this purpose the instruments were connected as shown in the dash line paths of fig.(5). in this arrangement the accelerometer was directly mounted on the vibrating part of the shaker and an electrical feedback signal was taken from the shaker input .the detected frequency ( fi ) by the accelerometer was fed to channel a of the oscilloscope while the feedback frequency ( fd ) was fed to channels b. the shaker was allowed to vibrate at specified sets of frequencies generated by the function generator (fs ) . these frequencies were 100, 500 and 1000 hz. the two output frequencies displayed on the oscilloscope were observed and recorded .then ,the overall accuracy for the exciter and the response sides for the three selected frequencies were calculated from the following relations : mohsen j.jweeg al-khwarizmi engineering journal, vol. 7, no. 4, pp17-26 (2011) 21 % over all accuracy of the exciter side ηex = 100x fs ffs i− % over all accuracy of the response side ηrs = 100x f ff i di − the calculated accuracies are shown in table (2) . this table shows that the accuracies are high and hence the errors are small. table2, overall accuracies of exciter and response side circuits at some selected frequencies. fs fi fd ηex ηrs 100 99.8 99.2 99.8% 99.2% 500 492 490 98.4% 98% 1000 990 985 99% 98.5% 4. experimental procedures the fundamental natural frequencies of the two models were measured at different water velocities and boundary conditions .in all cases the fundamental natural frequencies were firstly measured at zero flow rate and then the water flow rates are increased to 10 ,20 ,30 ,40 ,50 and 60 l/min .this was achieved by adjusting the controlling valve .it is important to mention that, since in some flow rates the flow is turbulent, the water was allowed for flowing about ten minutes prior any measuring.. in measuring the natural frequencies the test models were subjected to forced vibration under the effect of the harmonic force generated by the shaker to insure only force transmission to the models and avoiding the effect of the moment the connection between the models and the shaker shaft was made as a pin-joint connector by using a ball-bearing assembly. it is important to mention here that, it is necessary to minimize the amplitude of the excitation force due to the following reasons: 1insure a linear vibration since the amplitude remains small and within the elastic limit. 2reduce the effect of the modulation which may be taken between the vibrational wave of the test model and that of the foundation structure. 3minimize the effect of the impact which may be taken between the rotated parts such as the pinned supports and connectors. 4minimize the effect of structural and coulomb friction damping in the models. for this purpose the amplitude of the shaker was kept small within 2 v. this was done by adjusting the gain of the power amplifier .to compensate this reduction, the sensitivity of the accelerometer was raised to a maximum value by adjusting the gain of the conditioning amplifier to about 30mv. with the above arrangements refined vibrational waves which are necessary for accurate measuring were obtained on the oscilloscope. the response of the pipe models were picked by the accelerometer and displayed via the oscilloscope. in measuring the fundamental natural frequencies the excitation frequency of the shaker was gradually increased from zero observing the response until a sharp amplitude (resonance) was reached .at this instant the frequency was recorded . fig.(6) shows photograph of natural frequency tests for the pvc model at p-p boundary conditions . fig.6. a photograph for p-p, pvc pipe. 5. results and discussions for the illustration purpose the theoretical critical flow rates of buckling of the two models at different boundary conditions were calculated and presented in table 3 .table 3 shows the required high flow rates for the buckling of the two models. mohsen j.jweeg al-khwarizmi engineering journal, vol. 7, no. 4, pp17-26 (2011) 22 the measured natural frequencies and the associated fluid flow rates for the two models at different boundary conditions are given in table (4) and (5). table 3, critical flow rates (qc) for the test models at different boundary conditions. model no. material qc (p-p ) l/min qc (c-p) l/min qc (c-c) l/min 1 aluminum 238 357 476 2 pvc 101 151.5 202 table 4, measured fundamental natural frequencies (hz) for aluminum pipe at different boundary conditions . table 5, measured fundamental natural frequencies (hz) for pvc pipe at different boundary conditions . q(l/min) 0 10 20 30 40 50 60 p-p 7.2 6.6 6 5.9 5.4 5 2.5 c-p 8.1 8.2 8 7.75 7.3 6.7 6 c-c 12 11.8 11.5 11.2 11 10.4 9.9 the dimensionless frequencies ω and velocities u of the measured data then calculated from eqs.(7) and (8) . 0 0.5 1 1.5 140 145 150 155 160 165 170 u2 ω 2 exp. fitting fig.7.experimental plot of ω2against u2 for p-p aluminum pipe. in figs (7-12) the ω2 and u2 for the two models at the three considered boundary conditions are plotted and fitted to straight lines 0 0.5 1 1.5 280 285 290 295 300 305 310 315 u2 ω 2 exp. fitting fig. 8. experimental plot of ω2against u2 for c-p aluminum pipe. q(l/min) 0 10 20 30 40 50 60 p-p 13.2 13.0 12.9 12.6 12.4 11.9 11.8 c-p 17.75 17.85 17.6 17.6 17.5 17.4 16.7 p-p 25.7 25.7 25.77 25.6 25.57 25.2 25 mohsen j.jweeg al-khwarizmi engineering journal, vol. 7, no. 4, pp17-26 (2011) 23 0 0.5 1 1.5 625 630 635 640 645 650 655 660 u2 ω 2 exp. fitting fig. 9. experimental plot of ω2against u2 for c-c aluminum pipe. 0 2 4 6 8 40 45 50 55 60 65 u2 ω 2 exp. fitting fig.10. experimental plot of ω2against u2 for p-p pvc pipe. then, the equations of the fitted lines were evaluated and are given in table 6. table 6, equations of the fitted lines for figs. (7) to (12). comparing the equations given in table 6 with eq.(13) gives the estimated dimensionless critical velocities .finally, using eq.(7), the critical velocities for the two models were calculated. 0 2 4 6 8 10 15 20 25 30 35 40 45 50 u2 ω 2 exp. fitting fig. 11. experimental plot of ω2against u2 for c-p pvc pipe. 0 2 4 6 8 100 105 110 115 120 125 130 135 140 u2 ω 2 exp. fitting fig. 12. experimental plot of ω2against u2 for c-c pvc pipe. for example, to find the critical velocity of pp aluminum model the equation of the fitted line from table 6 is: ω2 =169.9-19.03u2 according to eq.(13) : ωb 2=169.9 and ( ωb/uc)2= 19.03 solving these equations give : uc = ٢.٩٨٨٠ now by using eq.(7) and substituting the aluminum pipe specifications shown in table 1,one get the following critical velocity : vc = 42.5032 m/s the results of the estimated and theoretical critical velocities of the two models and the associated errors are given in the tables 7 and 8. figure no. equation of fitted line boundary conditions 7 ω2 =169.9 -19.03 u2 p-p 8 ω2 =317.5 -17.27 u2 c-p 9 ω2 =663.2 -21.05 u2 c-c 10 ω2 =46.05 -4.406 u2 p-p 11 ω2 =67.29 -3.604 c-p 12 ω2 =139.3 -4.63 u2 c-c mohsen j.jweeg al-khwarizmi engineering journal, vol. 7, no. 4, pp17-26 (2011) 24 table 7, estimated and theoretical critical velocities for aluminum pipe . boundary conditions critical velocity(m/s) error% estimated theoretical p-p 42.5032 44.6884 -4.9 c-p 60.9916 64.0114 -4.7 c-c 79.8437 89.3767 -10.1 table 8, estimated and theoretical critical velocities for pvc pipe . boundary conditions critical velocity error% estimated theoretical p-p 18.2238 17.7091 2.9 c-p 24.3573 25.3664 -3.95 c-c 30.9194 35.4182 -12.4 tables 7 and 8 indicate that there is generally some errors between the theoretical and the estimated values of critical velocities these errors can be attributed to many reasons such as : 1. it is impossible to produce perfect boundary conditions in practice. 2. many sources of error such as instruments, reading, etc. 3. the effect of damping. also, tables 7 and 8 show that for pinnedpinned and clamped-pinned cases, the estimated critical velocities are very closed to the theoretical values since the errors are small. however for clamped-clamped case the errors are relatively high for the two models .this can be attributed to the fact that the critical velocities for clampedclamped pipe are higher than those for other boundary conditions . this will decrease the slope of the line given in eq.(13) .the small slope means that the variation in the fluid velocity lead to a small variation in the natural frequencies. this small variation is difficult to be detected experimentally unless a wider range of velocities are considered .thus, for accurate estimation the flow rate must be increased for clamped-clamped case . 6. conclusions the present approach provides an alternative simple experimental method for evaluating the critical velocities of buckling instead of the classical methods which require high flow rate pumps and sophisticated fluid circuits. the validity of present approach was checked by comparing its results with the theoretical ones. from the experimental results of two pipe models at different boundary conditions it can be concluded that, the present approach is more accurate for pinned-pinned and clamped–pinned pipes since the resulting errors are small .however for clamped-clamped pipes the accuracy is less unless higher flow rates are used. notations and nomenclatures p-p pinned-pinned c-p clamped – pinned c-c clampedclamped af.,ap fluid and pipe cross sectional area ,respectively.(m2) do,di outer and inner pipe diameter ,respectively .(m) e modulus of elasticity.(n/m2) i moment of inertia (m4) l pipe length.(m) mf, mp fluid and pipe mass per unit length, respectively .(kg/m) qc critical flow rate (l/min) u dimensionless fluid velocity. uc dimensionless critical buckling velocity v fluid velocity.(m/s) vc critical velocity of buckling (m/s) ω dimensionless frequency = ωl2[(mf + mp) /e i]1/2 ω circular frequency.(rad/sec) ωb dimensionless natural frequency of beams ρ fluid density (kg/m3 ) 7. references [1] paidoussis m..p.," fluid–structure interactions: slender structures and axial flow", 1. new york: academic press; 1998. [2] weaver d.s., and unny t.e., "on the dynamic stability of fluid conveying pipe"asme,,48-50,1973 [3] rao c. and simhab h.. "critical velocity of fluid-conveying pipes resting on twoparameter foundation" j.soun.vib.vol.302, 387-397, 2007. mohsen j.jweeg al-khwarizmi engineering journal, vol. 7, no. 4, pp17-26 (2011) 25 [4] bishop r.e. and fawzy i., "free and forced oscillation of vertical tube containing a flowing fluid" philosophical transactions of royal society of ,1970 [5] gregory r..w.and paidoussis m..p. ,"unstable oscillation of tubular cantilevers conveying fluid. i. theory ". proc royal soc london a vol.293, 512–27, 1966. [6] kuiper g.l. and metrlkine a..v., 'on stability of a clamped-pinned pipe conveying fluid', heron, vol 49 no.3, 211230,2004. [7] wang l. and ni q., " a note on the stability and chaotic motions of a restrained pipe conveying fluid"j.soun.vib.vol.296, 1079–1083,2006 [8] long r.h., "experimental and theoritical study of transverse vibration of a tube containing flowing fluid,"j.appl.mech.vol.22,65-68, 1955. [9] benjamin t.b., "dynamics of system of articulated pipes conveying fluid-i experimental “proc. roy. soc.(london),ser.a 261,488-498,1961. [10] blevins d.r., "flow-induced vibration", 1977. [11] gregory r.w.and paidoussis m..p., ,"unstable oscillation of tubular cantilevers conveying fluid. ii. experiments". proc. roy. soc. (london) ser. a 293,528–42, 1966. [12] huang y., liu y., li b., li y. and yue z., "natural frequency analysis of fluid conveying pipeline with different boundary conditions," nuclear engineering and design vol. 240,461–467, 2010. [13] ashrae systems and equipment handbook (si),41.3-41.4, 2000 [14] lawrence h. van vlack, "elements of materials science and engineering",1989. )2011( 17 26 ، صفحة3، العدد 7د مجلة الخوارزمي الھندسیة المجل جویج محسن جبر 26 ألحرجه لألنابيب الناقلة للموائع ذات الطاقة المحفوظة لسرع االنبعاج تخمين تجريبي * **البیر ایلیا یوسف *د رشید اسماعیلمحمو محسن جبر جویج جامعة النھرین/المیكانیكیةقسم الھندسة * جامعة النھرین/قسم الھندسة الطبیة ** الخالصة يجب استخدام تجريبيا ةب هذه السرعالغرض حسوحرجه ععند سر جا باالنبعاهتفقد استقرارالمحفوظة الطاقةالناقلة للمائع ذات األنابيب .السائل لمنظومةمضخات عاليه التصريف مما يسبب تعقيدات وبهذه ألطريقه يمكن استخدام أساسيهمن قياس عده ترددات طبيعيه ألحرجهالسرع تخمينتعتمد على جديدة تجريبيةفي هذا البحث تم تقديم طريقه .سرع قليله نسبيا ومنظومة سائل بسيطة لألنابيب ألحرجهلحساب السرع مالئمة ألطريقههذه أنج ئمنوعه فبينت النتا إسنادوتحت ظروف األنابيبتجارب على نموذجين من إجراءتم .المستخدم إال إذا تم زيادة مقدار الجريانمن جهتين المحكمة لألنابيبذلك اقل منمحكم بينما تكون -بسيط و بسيط -بسيط اإلسنادذات دراسة أداء محرك اشتعال انضغاطي ثنائي الوقود al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 8, no. 2, pp 97 -103 (2012) َضغاطالاب يحرك اشتعال تأثير َسثح طاقح وقىد انذيسل في وقىد ثُائي عهى أداءدراسح يعٍ جُاٌ تشير ثٌؾجِؼز ثٌضىٌٕٛٛؽ١ز/ لغُ ٕ٘ذعز ثٌّىجةٓ ٚثٌّؼذثس (received 15 september 2011; accepted 4 march 2012) انخالصح ، ٚرٌه ػٍٝ أدثء رٌه ثٌّقشن أفجدٜ ثالعطٛثٔز ٠ؼًّ دٛلٛد عٕجةٟ،ثشضؼجي دجالٔعغجغ صؤع١ش ٔغذز ٚلٛد ثٌذ٠ضي ثٌّقمْٛ فٟ ِقشن ٠ٙذف ثٌذقظ ٌذسثعز . فؾ١ّز ِخضٍفزدئظجفز ثٌغجص ثٌٕفطٟ ثٌّغجي إٌٝ ٚلٛد ثٌذ٠ضي دٕغخ صضدثد ثٌىفجءر ثٌقشثس٠ز ثٌّىذق١ز دض٠جدر ٔغذز ٚلٛد ثٌذ٠ضي ػٕذ ثألفّجي ثٌّٕخفعز، ٚصمً دض٠جدر ثٌقًّ، ٌٍٚقصٛي ػٍٝ صشغ١ً ِغضمش ٌّقشن ٠ؼًّ دٛلٛد . عٕجةٟ ٠ؾخ ثٌقفجظ ػٍٝ و١ّز ِٕجعذز ِٓ ٚلٛد ثٌذ٠ضي، إر ػٕذ ثٌؼًّ دؤلً ِٕٙج ٠ؼًّ ثٌّقشن دضشغ١ً غ١ش ٔظجِٟ ٠ٚقصً إخفجق دجالشضغجي -80)، أِج ػٕذ فًّ لش٠خ ِٓ ػٕذ أفّجي ؽضة١ز٠ىْٛ ثالعضٙالن ثٌٕٛػٟ ٌٍٛلٛد ٌّقشوجس عٕجة١ز ثٌٛلٛد أوذش ِٓ ل١ّضٙج ػٕذ ثٌؼًّ دٛلٛد د٠ضي فمػ . ، فجْ ثالعضٙالن ثٌٕٛػٟ ٌٍٛلٛد فٟ ِقشن عٕجةٟ ٠مضشح ِٓ ل١ّضٗ ػٕذ ثٌؼًّ دٛلٛد د٠ضي فمػ ثٌىٍِٟٓ ثٌقًّ (100% ٚلٛد عٕجةٟ، غجص ٔفطٟ ِغجي، ِقشن ثشضؼجي دجألٔعغجغ، ٔغذز ِىجفتز، لذسر ِىذق١ز، ثعضٙالن ٔٛػٟ ِىذقٟ، وفجءر فؾ١ّز، وفجءر : انكهًاخ انًفتاحيح .فشثس٠ز ِىذق١ز انًقذيح .1 صؼشف ِقشوجس ثٌٛلٛد ثٌغٕجةٟ دؤٔٙج ثٌّقشوجس ثٌضٟ ٠ّىٓ أْ صؼًّ ػٍٝ ٔٛػ١ٓ ِخضٍف١ٓ ِٓ ثٌٛلٛد، أفذّ٘ج ثٌٛلٛد ثٌغجصٞ . ٚث٢خش ٚلٛد عجةً، أٚ دؤٞ ِٓ ثٌٛلٛد٠ٓ دصٛسر ِٕفصٍز ٕٚ٘جن ػذر ػٛثًِ عجّ٘ش فٟ ثعضخذثَ ٘زث ثٌٕٛع ِٓ ثٌّقشوجس [1,2,3] ٟ٘ٚ : صٛفش ثٌٛلٛد ثٌغجصٞ دؤعؼجس ثسخص ِٓ ثٌٛلٛد ثٌغجةً، .1 .دجٌّمجسٔز ِغ ثٌم١ّز ثٌقشثس٠ز ثٌٕجصؾز ِٓ و١ٍّٙج .لشح ٔعٛح ثٌٛلٛد ثٌغجةً ثٌضم١ٍذٞ فٟ ثٌّغضمذً ثٌمش٠خ .2 لٍز ثٌضٍٛط ثٌقجصً ٌٍذ١تز ٔض١ؾز ٔظجفز ثالفضشثق ثٌٕجصؼ ِٓ .3 ِقشوجس ثٌٛلٛد ثٌغجصٞ ِمجسٔز ِغ ثٌّقشوجس ثٌضٟ صغضخذَ .ثٌٛلٛد ثٌغجةً غٛي ثٌؼّش ثٌضشغ١ٍٟ ٌٍّقشن ٔض١ؾز لٍز صخف١ف عجةً ثٌضض١٠ش، .4 .ٚلٍز ثٌضآوً ثٌقجصً د١ٓ ثألعطـ ثٌّضّجعز ٌٍّقشن عٌٙٛز ٔمً ثٌغجص ثٌّغجي دصٛسر ثلضصجد٠ز دغذخ ثٌضطٛسثس .5 .ثٌىذ١شر ثٌقجصٍز فٟ دٕجء ثٌخضثٔجس دغجغز ثٌّؼذثس ثٌالصِز ٌضق٠ًٛ ِقشن ثشضؼجي دجالٔعغجغ أٚ .6 دجٌششثسر إٌٝ ِقشن ٠ؼًّ دٛلٛد عٕجةٟ، ٚثِىج١ٔز صغ١١ش ػًّ ثٌّقشن ِٓ ٔٛع إٌٝ آخش دصٛسر صٍمجة١ز فٟ ثٌظشٚف .ثالظطشثس٠ز ٠ّٚىٓ ثٌؼًّ دؤٔٛثع ػذ٠ذر ِٓ ثٌٛلٛد ثٌغجصٞ فٟ ِقشوجس ثٌٛلٛد ثٌغٕجةٟ، ِٚٓ ثٌغجصثس ثٌّغضخذِز ثٌغجص ثٌطذ١ؼٟ، ثٌغجص ثٌٕفطٟ ثٌّغجي، ث١ٌٙذسٚؽ١ٓ ٚغجص ثٌفعالس [4,5] . ٌٚىٓ ٌٍٛلٛد ثٌغجصٞ ِغجٚا صقذ ِٓ ثعضخذثِٗ ٚصضطٍخ دسثعجس أوذش ٌٍضم١ًٍ ِٓ ثعش٘ج، فجٌٛلٛد ثٌغجصٞ ٠قضجػ ثٌٝ ٔغخ ثٔعغجغ ػج١ٌز الٔؾجص ػ١ٍّز ثالفضشثق دصٛسر وفٛءر، ٚرٌه السصفجع دسؽز فشثسر ثصمجدٖ ثٌزثصٟ، ٚٔغذز ثالٔعغجغ ثٌؼج١ٌز ٘زر غ١ش ِضٛفشر فٟ ِقشوجس ثالشضؼجي دجٌششثسر [11] . وّج ألْ فضشر صؤخش ثألشؼجي ٌٍٛلٛد ثٌغجصٞ أغٛي ِمجسٔز دجٌذ٠ضي دغذخ سلّٗ ثٌغ١ضجٟٔ ثأللً، وّج أْ ثٌىفجءر ثٌقؾ١ّز ٌقجٌز ٠ٚؾخ أْ ال صمً ثٌم١ّز . ٚلٛد غجصٞ ألً ِمجسٔز دٛلٛد د٠ضي ثٌقشثس٠ز ٌٍٛلٛد ثٌغجصٞ ثٌّغضخذَ فٟ ِقشن ٚلٛد عٕجةٟ ػٓ و١ٍٛؽٛي ٌٍّضش ثٌّىؼخ2430 [1] ٚصؤعش ػٛثًِ ػذ٠ذر فٟ . : غذ١ؼز ثالفضشثق ٌّقشوجس ثٌٛلٛد ثٌغٕجةٟ، ِٕٙج  ٠غضخذَ ٚلٛد ثٌذ٠ضي ١ٌغجػذ فٟ دذء : و١ّز ٚلٛد ثٌذ٠ضي ثالشضؼجي، ٠ٚقمٓ ػجدر لذً ثٌٕمطز ث١ٌّضز ثٌؼ١ٍج دؼذر دسؽجس لذً ثٔضٙجء شٛغ ثالٔعغجغ، فئرث وجٔش و١ّز ثٌٛلٛد ثٌّعخز وذ١شر فجْ و١ّز ثٌقشثسر ثٌّضقشسر ٚثٌّٕضمٍز إٌٝ ثٌخ١ٍػ عضىْٛ وذ١شر أ٠عج، ٠ٕٚضؼ ػٓ رٌه فصٛي ثفضشثق عش٠غ ٠صجفذٗ ثسصفجع فجد دجٌعغػ ثأللصٝ ٌألعطٛثٔز، ِّج ٠ؾؼً ثٌّقشن فٟ ظشٚف لش٠ذز ِٓ ظشٚف فجٌز ثٌطشق [2] ، أِج إرث وجٔش و١ّز ٚلٛد ثٌذ٠ضي ل١ٍٍز فغٛف صٕخفط ثٌمذسر ثٌخجسؽز ِٓ ثٌّقشن ٔض١ؾز ػذَ ثشضؼجي ثٌخ١ٍػ دصٛسر صجِز، ٚخشٚػ و١ّز ِٓ ثٌٛلٛد غ١ش ثٌّقضشق ِغ ثٌغجص ثٌؼجدَ [6,7] . ٌمذ أوذس ثغٍخ ثٌذسثعجس أْ ثفعً لذسر ٠ّىٓ ثٌقصٛي ػ١ٍٙج ِٓ ِقشن ٚلٛد عٕجةٟ ػٕذِج صىْٛ ٔغذز ٚلٛد ثٌذ٠ضي دجٌّجةز ِٓ ثٌطجلز ثٌقشثس٠ز ثٌى١ٍز ثٌذثخٍز إٌٝ 15 ث7ٌٝدقذٚد ثٌّقشن ػٕذ فًّ وٍٟ [11] .  ٓصؤع١ش صٛل١ش ثٌقم [1,2] ٠غذخ ثٌضٛل١ش ثٌّذىش ٌٍقمٓ ص٠جدر : فضشر صؤخ١ش ثالشضؼجي، ِغذذج ثسصفجع ل١ّز ثٌعغػ ثأللصٝ، ِّج ٠ض٠ذ ثفضّجي فصٛي فجٌز ثٌطشق، أِج ثٌضٛل١ش ثٌّضؤخش ٌٍقمٓ ف١مًٍ فضشر صؤخ١ش ثالشضؼجي، ِّج ٠ؤدٞ إٌٝ فصٛي ثالفضشثق دؼذ ثٌٕمطز ث١ٌّضز ثٌؼ١ٍج دذسؽجس ػذ٠ذر، ِّج ٠مًٍ ِٓ (2012) 103-97، انصفحح 2، انعذد8يجهح انخىارزيي انهُذسيح، انًجهذ يعٍ جُاٌ تشير 98 ثٌعغػ ثأللصٝ ٌألعطٛثٔز، ٚدجٌضجٌٟ ثٔخفجض ثٌمذسر .ثٌخجسؽز ِٓ ثٌّقشن  ٟٔصؤع١ش ثٌؼذد ثٌغ١ضج [3,8] ٠غذخ ثٔخفجض ثٌؼذد ثٌغ١ضجٟٔ ػٓ : ل١ّضٗ ثٌطذ١ؼ١ز ظؼف فٟ أدثء ػًّ ثٌّقشن ثٌٛلٛد ثٌغٕجةٟ، ٚثْ وجْ صؤع١ش ثٌؼذد ثٌغ١ضجٟٔ ل١ٍال فٟ غذ١ؼز ٚٔٛػ١ز ثالفضشثق ٌّقشوجس ثٌٛلٛد ثٌغٕجةٟ دجٌّمجسٔز ِغ ثٌؼذد .ثألٚوضجٟٔ ٌٍٛلٛد ثٌغجصٞ  صؤع١ش دسؽز فشثسر ثٌخ١ٍػ ثٌذثخً إٌٝ ثٌّقشن [1,3] صغذخ : ص٠جدر دسؽز فشثسر ثٌخ١ٍػ ثٌذثخً ٌالعطٛثٔز ػٕذ ثألفّجي ثٌؼج١ٌز ثٔخفجض ثٌمذسر ثٌخجسؽز ِٓ ثٌّقشن، ٚص٠جدصٙج ػٕذ ثألفّجي ثٌّٕخفعز صغضٛؽخ ثٌؼًّ دجٌؾجٔخ ثٌعؼ١ف (<1ø) إْ ثٔخفجض دسؽز فشثسر ثٌخ١ٍػ ػٕذ ثألفّجي ، ٠ؤدٞ إٌٝ (1ø<)ثٌؾضة١ز ٌٍّقشن ثٌؼجًِ دخ١ٍػ غٕٟ صقغ١ٓ ثٌىفجءر ثٌقشثس٠ز ٌٚىٓ ٠ؤعش ػٍٝ ِمذثس ثألعضٙالن ثٌٕٛػٟ ٌٍٛلٛد، د١ّٕج صٕخفط ثٌىفجءر فٟ فجٌز خ١ٍػ ظؼ١ف ٌؼذَ فصٛي ثالفضشثق ثٌضجَ، ٚخشٚػ و١ّز ِٓ ثٌٛلٛد ِغ .غجص ثٌؼجدَ  َصؤع١ش ٔٛع ثٌٛلٛد ثٌغجصٞ ثٌّغضخذ [1,9] ٠ؼضّذ صؤع١ش ٔٛع : ثٌٛلٛد ثٌغجصٞ ثٌّغضخذَ فٟ ِقشوجس ٚلٛد عٕجةٟ دشىً أعجعٟ ػٍٝ فذٚد ثشضؼجٌٗ ِٚمجِٚضٗ ٌٍطشق، ٚصخضٍف ٘جصجْ .ثٌخجص١ضجْ دجخضالف ِىٛٔجس ثٌغجص صؼطٟ وً أٔٛثع ثٌٛلٛد ثٌغجصٞ لذسر ػج١ٌز ػٕذ ثٌؼًّ فٟ ِٓ ثٌخ١ٍػ، ثوغش ِٓ ػٍّٙج فٟ ثٌؾجٔخ (1ø<)ثٌؾجٔخ ثٌغٕٟ ، ٚأغٍذٙج ٌٙج ِمجِٚز ػج١ٌز ٌٍطشق، ٚصؼضّذ (1ø<)ثٌعؼ١ف ثٌٕغذز ثٌّىجفتز ثٌذثخٍز إٌٝ ِقشن ثٌٛلٛد ثٌغٕجةٟ دذسؽز سة١غ١ز ػٍٝ و١ّز ٚلٛد ثٌذ٠ضي ثٌالصِز إلشؼجي ثٌخ١ٍػ فٟ غشفز ثالفضشثق، ٌزث ٠ّىٓ ثٌقصٛي ػٍٝ لذسر ػج١ٌز ِٓ ثٌّقشن ػٕذ ثٌؼًّ دخ١ٍػ ظؼ١ف، ألٔٗ ٠ّضجص دفضشر صؤخ١ش غ٠ٍٛز ٔغذ١ج، ٚدّؼذي ثفضشثق دطٟء، ٠ؤدٞ إٌٝ ثلضشثح ِٛظغ ثٌعغػ ثأللصٝ ٌألعطٛثٔز ِٓ ثٌٕمطز ث١ٌّضٗ ثٌؼ١ٍج، ِّج ٠ض٠ذ ِٓ وفجءر ثالفضشثق، أِج ثٌؼًّ دجٌؾجٔخ ثٌغٕٟ ِٓ ثٌخ١ٍػ، فغٛف ٠قذط ثفضشثق عش٠غ ِٚفجؽب، ٠صجفذٗ ثسصفجع فجد فٟ ظغػ ثالعطٛثٔز ثأللصٝ ِغذذج فجٌز ثٌطشق [10] . صٙذف ثٌذسثعز ٌضٛظ١ـ صؤع١ش ٔغخ غجلز ٚلٛد ثٌذ٠ضي ثٌذثخٍز ثٌٝ ثٌّقشن ِمجسٔز دجٌطجلز ثٌى١ٍز ػٍٝ أدثء ِقشن أفجدٞ . دجالٔعغجغثألعطٛثٔز ٠ؼًّ األجهسج انًستخذيح .2 صّش ثٌضؾجسح دجعضخذثَ ِقشن أفضشثق دثخٍٟ ٠ؼًّ -1 دجالٔعغجغ أفجدٞ ثالعطٛثٔز سدجػٟ ثالشٛثغ رٚ ٔغخ ,prodit, gr0306/000/037a)ثٔعغجغ ِضغ١شر، ٔٛع italy) ُِٛثصفجس ثٌّقشن ثٌّغضخذَ ٠ٚ1ٛظـ ؽذٚي سل . فٟ ثٌؼًّ ٠مجط ثٌٙٛثء ثٌّؾٙض ثٌٝ ثٌّقشن دٛثعطز ِم١جط فٛ٘ز، -2 ثٔذٛح عقخ ثٌٙٛثء، غشفز : ٠ٚضىْٛ ٔظجَ صؾ١ٙض ثٌٙٛثء ِٓ . صخ١ّذ، ِٚقٛي ثٌمذسر ٌٍعغػ ثٌضفجظٍٟ ٠غضخذَ ثٌذ٠ٕج١ِِٛضش ث١ٌٙذس١ٌٚىٟ ٌم١جط ػضَ ثٌّقشن -3 . ثٌخجسػ صمجط دسؽز فشثسر ثٌغجص ثٌؼجدَ دجعضخذثَ ِضدٚؽجس فشثس٠ز -4 . مثبتة عند بداية أنبوب العادمk (ni-cr)/(ni-al)ٔٛع :ٔظجَ صؾ١ٙض ثٌّقشن دجٌغجص ثٌٕفطٟ ثٌّغجي -5 صضىْٛ ثٌّٕظِٛز ثٌّغضخذِز فٟ ثٌذقظ ٌضؾ١ٙض ثٌّقشن دجٌغجص خضثْ ثٌٛلٛد، ِششـ ثٌٛلٛد، : ثٌٕفطٟ ثٌّغجي ِٓ ثألؽضثء ثٌضج١ٌز ِغٕجغ١غٟ، ِذخش ثٌغجص ثٌٕفطٟ ثٌّغجي، ِم١جط صذفك ٚصّجَ وٙش ِم١جط فٛ٘ز ِصُّ فغخ ثٌّٛثصفجس ثٌذش٠طج١ٔز، ثٌٛلٛد ثٌغجصٞ ، صٕذٚق ثٌضخ١ّذ، ِغزٞ (m=0.05353)ٚٔغذز ثٌّغجفز ٌٗ ٚلذ صُ ثعضخذثَ ثٌغجص ثٌٕفطٟ ثٌّغجي ثٌّٕضؼ . ِٚجٔؼز ثٌٍٙخثٌغجص إ٠غجْ، % 1: ثٌؼشثق، ٚثٌّىْٛ ِٓ– ِٓ ششوز غجص ثٌضجؽٟ . د١ٛصجْ. ْ% 32.65أ٠ضٚد١ٛصجْ،% 18.17دشٚدجْ، % 48.18 صضىْٛ ثٌّٕظِٛز : ٔظجَ صؾ١ٙض ثٌّقشن دٛلٛد ثٌذ٠ضي -6 ثٌّغضخذِز فٟ ثٌذقظ ِٓ خضثْ ٚلٛد د٠ضي، ِم١جط فؾُ ٚلذ ثعضخذَ فٟ ٘زث ثٌذقظ . ثٌٛلٛد، ِششـ ثٌٛلٛد ٚثٌصّجَ ثٌؼشثق، ٚدشلُ دغذثد-ٚلٛد د٠ضي ِٕضؼ ِٓ ِصفٝ ثٌذٚسر . 47.8ع١ضجٟٔ ِخطػ ٌٍؾٙجص ثٌّغضخذَ فٟ ثٌضؾجسح ِغ وجًِ ٠1ذ١ٓ ثٌشىً . ٍِقمجصٗ . يخطظ نألجهسج انًستخذيح في انتجارب-1-شكم ثعضخذِش ثٌّؼجدالس ثٌضج١ٌز ٌقغجح ِضغ١شثس ثٌّقشن ثٌّّٙز :ٚوّج ٠ٍٟ ثٌمذسر ثٌّىذق١ز .1 𝑏𝑝 = 𝑊𝑏 × 𝑁/348.067 .ثٌقًّ ثٌّغٍػ دج١ٌٕٛصٓwb: ف١ظ n عج١ٔز/ عشػز ثٌّقشن دٚسر. ثٌٕغذز ثٌّىجفتز .2 ø= (a/f)stoichiometric/ (a/f)actual ثالعضٙالن ثٌٕٛػٟ ثٌّىذقٟ ٌٍٛلٛد .3 𝑏𝑠𝑓𝑐 = 𝑚𝑓 ° × 3600/𝑏𝑝 m: ف١ظ o f – ثٌغجص ثٌٕفطٟ ثٌّغجي )ِؼذي ثعضٙالن ثٌٛلٛد + .(ثٌذ٠ضي ثٌىفجءر ثٌقؾ١ّز .4 𝜂𝑣𝑜𝑙 = 𝑚𝑎 𝑎𝑐𝑡 /(𝑚𝑎)𝑡𝑕𝑒𝑜 . × 100 . وضٍز ثٌٙٛثء ثٌّضذفمز دثخً ثٌّقشن ػ١ٍّج.act(ma): ف١ظ (ma)theo. -وضٍز ثٌٙٛثء ثٌّضذفمز دثخً ثٌّقشن ٔظش٠ج . (2012) 103-97، انصفحح 2، انعذد8يجهح انخىارزيي انهُذسيح، انًجهذ يعٍ جُاٌ تشير 99 ٔغذز ثٌطجلز ثٌقشثس٠ز ٌٛلٛد ثٌذ٠ضي ثٌٝ ثٌطجلز ثٌى١ٍز ٌخ١ٍػ .5 :ثٌٛلٛد ثٌذثخً ٌٍّقشن 𝑑𝑖𝑒𝑠𝑒𝑙 𝑓𝑢𝑒𝑙 𝑒𝑛𝑒𝑟𝑔𝑦 𝑟𝑎𝑡𝑖𝑜 = 𝑚𝑑𝑖𝑒𝑠𝑒𝑙 ° × 𝐿𝐻𝑉𝑑𝑖𝑒𝑠𝑒𝑙 𝑚𝑑𝑖𝑒𝑠𝑒𝑙 ° × 𝐿𝐻𝑉𝑑𝑖𝑒𝑠𝑒𝑙 + 𝑚𝐿𝑃𝐺 ° × 𝐿𝐻𝑉𝐿𝑃𝐺 :خطٛثس إؽشثء ثٌضؾجسح صّش ثٌضؾجسح دؼذ صشغ١ً ثٌّقشن ٌفضشر ِٓ ثٌضِٓ ٚٚصٌٛٗ ° 60 ٚٚصٛي دسؽز فشثسر ص٠ش ثٌّقشن ٌذسؽز ثالعضمشثسٌقجٌز ِت٠ٛز، ° 5° ± 70، ٚدسؽز فشثسر ِجء ثٌضذش٠ذ ٌذسؽز °5± ِت٠ٛز : دؼذ رٌه صُ صغ١١ش ثٌؼٛثًِ ثٌّزوٛسر ٚوّج ٠ٍٟ ثػضذشس ثٌقجٌز ثألعجع١ز )ٔٛع ثٌٛلٛد ِٓ ٚلٛد د٠ضي ٔمٟ .1 ، ثٌٝ ٚلٛد عٕجةٟ (دجعضخذثَ ثٌذ٠ضي دّفشدٖ ألغشثض ثٌّمجسٔز .ِىْٛ ِٓ د٠ضي ٚغجص ٔفطٟ ِغجي .صغ١١ش فًّ ثٌّقشن ِٓ دال فًّ ٌٚغج٠ز ثٌقًّ ثٌىٍٟ .2 لذً ثٌٕمطز ° 45 ٌٚغج٠ز 20صغ١١شصٛل١ش فمٓ ٚلٛد ثٌذ٠ضي ِٓ .3 °.5ث١ٌّضٗ ثٌؼ١ٍج ٚدخطٛثس وً ِٕٙج ػذجسر ػٓ انًُاقشح .3 ثٌؼاللز د١ٓ ثالعضٙالن ثٌٕٛػٟ ثٌّىذقٟ ٌٍٛلٛد ٠2ٛظـ شىً ٚٔغذز ثٌطجلز ثٌقشثس٠ز ٌٛلٛد ثٌذ٠ضي إٌٝ ثٌطجلز ثٌى١ٍز ثٌذثخٍز . ٌٍّقشن ػٕذ ػًّ ثٌّقشن دؤفّجي ِقذدر 208)٠قذط ثوذش ثعضٙالن ٔٛػٟ ٌٍٛلٛد ٌألفّجي ثٌّٕخفعز kpa) ػٕذ ثلً ٔغذز ٌٛلٛد د٠ضي، ٔض١ؾز ظؼف لٛر ثٌخ١ٍػ ٚثٔخفجض وفجءر ثالفضشثق، ِٚغ ثسصفجع ٔغذز ٚلٛد ثٌذ٠ضي ٠ذذأ ثالعضٙالن ثٌٕٛػٟ ٌٍٛلٛد دجالٔخفجض، ألْ ص٠جدر و١ّز ٚلٛد ثٌذ٠ضي صؤدٞ إٌٝ ثسصفجع ثٌطجلز ثٌقشثس٠ز ثٌّٕضمٍز ِٕٙج إٌٝ ثٌٛلٛد ثٌغجصٞ، ٚدجٌضجٌٟ ثٔخفجض و١ّز ثٌٛلٛد غ١ش ثٌّقضشق ثٌزٞ ٠خشػ . ِغ ثٌغجص ثٌؼجدَ انعالقح تيٍ االستهالك انُىعي نهىقىد وَسثح انطاقح انحراريح -2-شكم نىقىد انذيسل إنى انطاقح انكهيح انذاخهح نهًحرك عُذ عًم انًحرك .تأحًال يتغيرج ٠ٚؼٛد ثالعضٙالن ثٌٕٛػٟ ٌٍٛلٛد ٌالصد٠جد ِشر أخشٜ ػٕذ ػًّ ثٌّقشن فمػ دٛلٛد ثٌذ٠ضي، ٚرٌه ألْ ِقشوجس ثٌذ٠ضي صّضجص ػِّٛج دجسصفجع ثالعضٙالن ثٌٕٛػٟ ٌٍٛلٛد ػٕذ ثألفّجي ثٌّٕخفعز، ٔض١ؾز الٔخفجض ثٌٕغذز ثٌّىجفتز ٚػذَ ثفضشثق ٚلٛد ثٌذ٠ضي . دصٛسر صجِز فؤْ أػٍٝ ثعضٙالن ((kpa 521-315ػٕذ ثألفّجي ثٌّضٛعطز ٔٛػٟ ٌٍٛلٛد ٠قذط أ٠عج ػٕذ ثلً ٔغذز ٌٛلٛد ثٌذ٠ضي، ٠ٚغضّش دجالٔخفجض ِغ ثسصفجع ٘زر ثٌٕغذز إٌٝ أْ ٠صً إٌٝ ثلً ل١ّز ٌٗ ػٕذ ػًّ ثٌّقشن فمػ دٛلٛد ثٌذ٠ضي، ٚرٌه ألْ ص٠جدر ثٌقًّ ٚثٔخفجض صشو١ض ثٌٛلٛد ثٌغجصٞ فٟ ثٌخ١ٍػ ٠ؤدٞ إٌٝ ص٠جدر و١ّز ثٌٙٛثء ثٌذثخً ٌٍّقشن ٚصقغٓ ثٌىفجءر ثٌقؾ١ّز ٌٍّقشن، ِٚٓ عُ . ص٠جدر وفجءر ثالفضشثق ، فؤْ ثلً ثعضٙالن ٔٛػٟ (kpa 652)أِج ػٕذ ثألفّجي ثٌؼج١ٌز ٌٍٛلٛد ٠قذط ػٕذ ثلً ٔغذز ٌٛلٛد ثٌذ٠ضي، دغذخ ص٠جدر فشثسر غشفز ثألفضشثق ٚثٔخفجض و١ّز ثٌٛلٛد غ١ش ثٌّقضشق، ٠ٚىْٛ أػٍٝ ل١ّٗ ٌألعضٙالن ثٌٕٛػٟ ثٌّىذقٟ ٌٍٛلٛد ػٕذ ػًّ ثٌّقشن دٛلٛد ثٌذ٠ضي دّفشدٖ، ٚرٌه ٌؼذَ صٛفش فضشر ص١ِٕز وجف١ز ٌقشق ثٌٛلٛد دصٛسر صجِز، ِّج ٠ؤدٞ إٌٝ خشٚػ و١ّز ِٕٗ ِغ ثٌغجص . ثٌؼجدَ، ثألِش ثٌزٞ ٠ؤدٞ إٌٝ ص٠جدر ثالعضٙالن ثٌٕٛػٟ ٌٍٛلٛد ثٌؼاللز د١ٓ ثٌىفجءر ثٌقشثس٠ز ثٌّىذق١ز ِٚؼذي ٠3ٛظـ ثٌشىً غجلز ثٌذ٠ضي ثٌذثخٍز ٌٍّقشن ألفّجي ِقذدر، إر صذذأ وً ثٌّٕق١ٕجس ِٓ ٔمطز فصٛي إخفجق ثالشضؼجي ٔض١ؾز ٌؼذَ صٛفش ٚلٛد ثٌذ٠ضي . دى١ّجس وجف١ز ٌقصٛي ػ١ٍّز ثالفضشثق دصٛسر ِغضمشر ٠ؤدٞ ػًّ ثٌّقشن دؤفّجي ؽضة١ز ِغ صم١ًٍ ٔغذز ٚلٛد ثٌذ٠ضي ٚعذٛس ثٌقًّ إٌٝ ثٔخفجض ثٌىفجءر ثٌقشثس٠ز ثٌّىذق١ز ٌٍّقشن، ٠ٚذشص ثٌضؤع١ش ثوغش ٚظٛفج ػٕذ ثألفّجي ثٌّٕخفعز، إر أْ ص٠جدر % 100 إٌٝ 11.1ِٚٓ % 100 إٌٝ 15.7ٔغذز ٚلٛد ثٌذ٠ضي ِٓ 17دجس، صؤدٞ إٌٝ ص٠جدر ثٌىفجءر دٕغذز ( 5.33 ٚ 3.08)ألفّجي . ػٍٝ ثٌضٛثٌٟ% 10ٚ انعالقح تيٍ انكفاءج انحراريح انًكثحيح وَسثح انطاقح -3-شكم .انحراريح نىقىد انذيسل إنى انطاقح انكهيح انذاخهح إنى انًحرك أِج ػٕذ ػًّ ثٌّقشن دقًّ لش٠خ ِٓ ثٌقًّ أللصٝ دقذٚد دجس، فمذ ٌٛفع صغجٚٞ ل١ُ ثٌىفجءر ثٌقشثس٠ز ٌّقشن ٚلٛد 7.52 عٕجةٟ ٌقجٌز ثٌؼًّ دٛلٛد د٠ضي فمػ، ٚرٌه الْ ِقشن عٕجةٟ ثٌٛلٛد ٠ّىٓ أْ ٠قشق و١ّز ثوذش ِٓ ثٌٛلٛد ثٌغجصٞ ثٌزٞ ٠ّأل غشفز ثالفضشثق، ٔض١ؾز ٌضى٠ٛٓ ثٌؼذ٠ذ ِٓ ؽذٙجس ثٌٍٙخ ثٌّٕضششر دثخً غشفز ثالفضشثق ٚثٌقصٛي ػٍٝ ثفضشثق دصٛسر وفٛءر، ٚدجٌضجٌٟ ص٠جدر ثٌمذسر ثٌٕجصؾز ِٓ ثٌّقشن، أِج ػٕذِج ٠ىْٛ ثٌٛلٛد عجةال فجْ لطشثس ثٌذ٠ضي ال ٠ّىٓ أْ صشغً ف١ض غشفز ثالفضشثق دؤوٍّٙج، 200 300 400 500 0 10 20 30 40 50 60 70 80 90 100 s p e c if ic f u e l c o n su m p ti o n (g /k w .h r ) diesel fuel energy rate (%) n=1000 rpm, it=26btdc, cr=16.21:1 bmep=652kpa bmep=521kpa bmep=433kpa bmep=315kpa bmep=208kpa 10 15 20 25 30 0 20 40 60 80 100 b r a k e t h e r m a l e ff ic ie n c y diesel fuel energy rate n=1000rpm, it=26btdc, cr=16.21:1 bmep=652 kpa bmep=5621 kpa bmep=433 kpa bmep=315 kpa bmep=208 kpa (2012) 103-97، انصفحح 2، انعذد8يجهح انخىارزيي انهُذسيح، انًجهذ يعٍ جُاٌ تشير 100 ٠ٕٚضؼ ػٓ رٌه خشٚػ و١ّز ِٓ ثٌٛلٛد غ١ش ثٌّقضشق ِغ ثٌغجص . ثٌؼجدَ ٔالفع ِٓ ثٌّٕق١ٕجس أْ ص٠جدر ثٌقًّ صؤدٞ إٌٝ ص٠جدر ثٌىفجءر ثٌقشثس٠ز ثٌّىذق١ز ٌٕفظ ثٌىضٍز، ٚرٌه الْ ص٠جدر ثٌقًّ صؤدٞ إٌٝ . صقغ١ٓ وفجءر ثالفضشثق انعالقح تيٍ انكفاءج انحراريح انًكثحيح ويتىسظ انضغظ انفعال -4-شكم عُذ عًم انًحرك تىقىد ديسل فقظ، وتأقم َسثح يٍ انطاقح انحراريح .نىقىد ديسل إنى انطاقح انكهيح انذاخهح نهًحرك ثٌؼاللز د١ٓ ثٌىفجءر ثٌقشثس٠ز ثٌّىذق١ز ٠4ٛظـ شىً ِٚضٛعػ ثٌعغػ ثٌفؼجي ػٕذ ػًّ ثٌّقشن دٛلٛد د٠ضي ، ٚدؤلً ٔغذز ِٓ ثٌطجلز ثٌقشثس٠ز ٌٛلٛد د٠ضي إٌٝ %(100) . ثٌطجلز ثٌى١ٍز ثٌذثخٍز ٌٍّقشن صضشثٚؿ ثلً ٔغذز ِٓ ٚلٛد ثٌذ٠ضي ثٌالصِز ٌؼًّ ثٌّقشن عٕجةٟ ثٌٛلٛد دصٛسر ِغضمشر ٚدغذٛس وً ِٓ ثٌغشػز ٚصٛل١ش إٌٝ 18.2ثٌقمٓ ٚٔغذز ثالٔعغجغ ٚألفّجي ِخضٍفز دقذٚد ِٓ أِج ػٕذ . ِٓ ثٌطجلز ثٌقشثس٠ز ثٌذثخٍز إٌٝ ثٌّقشن% 19.3 ثألفّجي ثٌمصٜٛ ٚثٌمش٠ذز ِٕٙج ف١ٍضمٟ ثٌّٕق١ٕجْ ػٕذ ٔمطز ِؼ١ٕز، ِّج ٠ؼٕٟ أْ أظجفز و١ّجس أوذش ِٓ ٚلٛد ثٌذ٠ضي غ١ش ِذشسر ٚال صغذخ ص٠جدر صزوش فٟ ل١ُ ثٌىفجءر ثٌقشثس٠ز ثٌّىذق١ز ٌٍّقشن، وّج . ٠ذ١ٓ ثٌشىً انعالقح تيٍ انطاقح انحراريح انتي يستههكها انًحرك وَسثح -5-شكم .انطاقح انحراريح نىقىد انذيسل إنى انطاقح انكهيح ، ٚثٌزٞ 5أِج ػٕذ ػًّ ثٌّقشن دذْٚ فًّ، وّج ٠ٛظـ شىً ٠ذ١ٓ ثٌؼاللز د١ٓ ثٌطجلز ثٌقشثس٠ز ثٌضٟ ٠غضٍٙىٙج ثٌّقشن ٚٔغذز ثٌطجلز ثٌقشثس٠ز ٌٛلٛد ثٌذ٠ضي إٌٝ ثٌطجلز ثٌى١ٍز، فجْ ثٔخفجض و١ّز ثٌٛلٛد غ١ش ثٌّقضشق ٚثسصفجع ثٌطجلز ثٌقشثس٠ز ثٌضٟ ٠غضٍٙىٙج ثٌّقشن صغذخ ص٠جدر وفجءر ثالفضشثق فٟ ثٌٕغخ ثٌؼج١ٌز ٌٛلٛد أِج ثٔخفجض ٔغذز ٚلٛد ثٌذ٠ضي فضؤدٞ إٌٝ ػذَ ثفضشثق . ثٌذ٠ضي ثٌٛلٛد دصٛسر صجِز، ِّج ٠غضذػٟ ص٠جدر و١ّز ثٌٛلٛد ثٌضٟ ٠قضجؽٙج .ثٌّقشن ٌٍقفجظ ػٍٝ ثٌغشػز ثٌّطٍٛدز ، ثٌؼاللز د١ٓ ل١ُ ثٌعغػ ثٌّغؾٍز ٌٕغخ ِخضٍفز ٠6ذ١ٓ شىً ِٓ ثٌطجلز ثٌقشثس٠ز ٌٛلٛد ثٌذ٠ضي إٌٝ ثٌطجلز ثٌى١ٍز ثٌذثخٍز ٌٍّقشن، ٠ٚالفع ثٔخفجض ثٌم١ّز ثٌمصٜٛ ٌٍعغػ ػٕذ ثألفّجي ثٌؾضة١ز فٟ فجٌز ػًّ ثٌّقشن دٕغخ ِٕخفعز ِٓ ٚلٛد ثٌذ٠ضي، إْ ل١ّز ثٌعغػ ثأللصٝ ٌألعطٛثٔز ِٕخفعز، ٚصضدثد ِغ ص٠جدر .ٔغذز ثٌٛلٛد ثٌذ٠ضي إٌٝ أْ صصً إٌٝ أػٍٝ ل١ّز ٌٙج ٚػٕذ ثألفّجي ثٌّضٛعطز فؤْ ثٔخفجض و١ّز ثٌٛلٛد ثٌغجصٞ فٟ ثٌخ١ٍػ صغذخ ص٠جدر و١ّز ثٌٙٛثء ثٌذثخً ٌألعطٛثٔز، ٚأْ ثسصفجع ٔغذز ٚلٛد ثٌذ٠ضي صؤدٞ إٌٝ ص٠جدر و١ّز ثٌقشثسر ثٌّضقشسر ِٕٗ . ٚثٌّٕضمٍز إٌٝ ثٌٛلٛد ثٌغجصٞ ِّج ٠ض٠ذ ِٓ وفجءر ثالفضشثق أِج ػٕذ فًّ لش٠خ ِٓ ثٌقًّ ثأللصٝ فؤْ أػٍٝ ل١ّز ٌٍعغػ دثخً ثالعطٛثٔز صقذط ػٕذ ػًّ ثٌّقشن دؤلً ٔغذز ِٓ ٚلٛد ثٌذ٠ضي، ٚصذذأ ثٌم١ّز دجالٔخفجض ثٌضذس٠ؾٟ ِغ ص٠جدر ٔغذز ٚلٛد ثٌذ٠ضي، ٔض١ؾز ٔمصجْ فضشر صؤخ١ش ثالشضؼجي، ٚػذَ صٛفش فضشر ص١ِٕز وجف١ز ٌضقع١ش أوذش و١ّز ِٓ ثٌٛلٛد ثٌؾج٘ض ٌالشضؼجي، ٚثْ غذ١ؼز ثٌخٍػ فٟ ثٌٕغخ ثٌؼج١ٌز ٌٍٛلٛد ثٌغجصٞ فٟ ِقشن ٚلٛد عٕجةٟ ػٕذ ثألفّجي ثٌؼج١ٌز ثفعً دىغ١ش ِٓ غذ١ؼز ثٌخٍػ فٟ ِقشن ٠ؼًّ دجٌذ٠ضي فمػ، ِّج ٠ؤدٞ إٌٝ صمذَ ٚثٔضشجس ثٌٍٙخ، ٚفصٛي ثالفضشثق دصٛسر عش٠ؼز ٚوفٛءر، إرث ثٔخفعش ثٌم١ّز ثٌمصٜٛ . ٌٍعغػ ػٕذ ػًّ ثٌّقشن فمػ دٛلٛد ثٌذ٠ضي قيى انضغظ انًسجهح نًجًىعح انتجارب نُسة يختهفح يٍ -6شكم .انطاقح انحراريح نىقىد انذيسل إنى انطاقح انكهيح انذاخهح نهًحرك إْ فضشر صؤخ١ش ثالشضؼجي ثٌّمجعز دذالٌز دسؽجس ػّٛد ثٌّشفك ِٓ ِٕقٕٝ ثٌعغػ ِغ دسؽجس ػّٛد ثٌّشفك، صّغً ثٌفضشر ثٌّقصٛسر ِٓ دذث٠ز فمٓ ثٌٛلٛد إٌٝ ثٌذسؽز ثٌضٟ ٠ٕفصً ف١ٙج ِٕقٕٝ ثٌعغػ ػٕذ فصٛي ثالفضشثق ػٓ ِٕقٕٝ ثٌعغػ ٌٍٙٛثء . فٟ فجٌز صذ٠ٚش ثٌّقشن دغذٛس ثٌغشػز ، ثٌؼاللز د١ٓ ثٌذسؽز ثٌضٟ ٠ضُ دٙج دذء ثالشضؼجي ٠7ٛظـ شىً دسؽز لذً ثٌٕمطز ث١ٌّضز ثٌؼ١ٍج، ٌٕغخ 26دغذٛس صٛل١ش ثٌقمٓ ػٕذ 0 5 10 15 20 25 30 35 0 200 400 600 800 1000 b r a k e t h e r m a l e ff ic ie n c y brake mean effictive pressure n=1000rpm, it=26 btdc, cr=16.21:1 100% diesel fuel min. percentage of diesel fuel 10 12 14 16 18 0 20 40 60 80 100 e n e r g y i n si d e e n g in e ( k w ) diesel fuel energy rate n=1000 rpm, it=26btdc, cr=16.21:1 300 400 500 600 700 800 0 20 40 60 80 100 c y li n d e r m a x . p r e ss u r e diesel fuel energy rate n=1000 rpm, it=26 btdc, cr=16.21 bmep=652 kpa bmep=521 kpa bmep=433 kpa bmep=315 kpa bmep=208 kpa bmep=0 kpa (2012) 103-97، انصفحح 2، انعذد8يجهح انخىارزيي انهُذسيح، انًجهذ يعٍ جُاٌ تشير 101 ِخضٍفز ِٓ ثٌطجلز ثٌقشثس٠ز ٌٛلٛد ثٌذ٠ضي إٌٝ ثٌطجلز ثٌى١ٍز ثٌذثخٍز إر ٌٛفع ص٠جدر فضشر ثٌضؤخ١ش ػٕذ ثٌٕغخ . ٌٍّقشن ٚدؤفّجي ِخضٍفز ثٌؼج١ٌز ٌٍٛلٛد ثٌغجصٞ، ٚال صٍذظ أْ صٕخفط ِغ ٔمصجْ ٘زر ٚرٌه الْ ص٠جدر ٔغذز ثٌٛلٛد ثٌغجصٞ فٟ ثٌخ١ٍػ صؤدٞ إٌٝ ثٌٕغذز، ثٔخفجض و١ّز ثٌٙٛثء ثٌذثخً ٌٍّقشن ٔض١ؾز ثٌقؾُ ثٌزٞ ٠شغٍٗ دذال ِٓ ثٌٙٛثء، وّج صغذخ ص٠جدر غٛي فضشر ثٌضؤخ١ش ثٌى١ّ١جة١ز ٌٍخ١ٍػ . ٔض١ؾز ػذَ صٛفش ثألوغؾ١ٓ دى١ّجس وذ١شر انعالقح تيٍ تأخر األشعال وَسة انطاقح انحراريح نىقىد انذيسل -7-شكم .إنى انطاقح انكهيح انذاخهح نهًحرك ألحًال يختهفح صضؤعش فضشر صؤخ١ش ثالشضؼجي دجٌعغػ ٚدسؽز فشثسر ثٌخ١ٍػ أعٕجء شٛغ ثالٔعغجغ، إر صمً ٘زر ثٌفضشر دض٠جدر دسؽز ثٌقشثسر ٚثٌعغػ ٌٍخ١ٍػ، ٚدّج أْ ص٠جدر ثٌقًّ صغذخ ص٠جدر دسؽز فشثسر ِىٛٔجس . ثالعطٛثٔز، ٌزث صمً ٘زر ثٌفضشر االستُتاجاخ .4 صؤدٞ ص٠جدر ٔغذز ٚلٛد ثٌذ٠ضي فٟ ثألفّجي ثٌّٕخفعز إٌٝ .1 ثٔخفجض ثالعضٙالن ثٌٕٛػٟ ٌٍٛلٛد، إٌٝ أْ صصً ثلً ل١ّز ٌٗ ِٓ ٚلٛد ثٌذ٠ضي، دؼذ رٌه % 60 ٌغج٠ز 40ػٕذ ٔغخ دقذٚد . ٠ؼٛد ٌالسصفجع ِشر أخشٜ ٠قصً أػٍٝ ثعضٙالن ٔٛػٟ ٌٍٛلٛد فٟ ثألفّجي ثٌّضٛعطز .2 ٚػٕذ فًّ لش٠خ ِٓ ثٌقًّ . ػٕذ ثلً ٔغذز ِٓ ٚلٛد ثٌذ٠ضي ثٌىٍٟ ٠قذط ثلً ثعضٙالن ٔٛػٟ ٌٍٛلٛد ػٕذ ثلً ٔغذز ِٓ .ٚلٛد ثٌذ٠ضي صغذخ ص٠جدر ٔغذز ٚلٛد ثٌذ٠ضي فٟ ثألفّجي ثٌّٕخفعز إٌٝ .3 ثسصفجع ثٌىفجءر ثٌقشثس٠ز ثٌّىذق١ز صذس٠ؾ١ج، ٚدصٛسر أٚظـ إْ . ِّج ٘ٛ ػ١ٍٗ ثٌقجي ػٕذ ػًّ ثٌّقشن دؤفّجي ِضٛعطز ثٌىفجءر ثٌقشثس٠ز ثٌّىذق١ز ٌّقشن ٚلٛد عٕجةٟ فٟ ثألفّجي .ثٌؼج١ٌز ثوذش ِٓ ل١ّٙج ػٕذ ثٌؼًّ دجألفّجي ثٌؾضة١ز ػٕذ ػًّ ثٌّقشن دقًّ لش٠خ ِٓ ثٌقًّ ثٌىٍٟ فؤْ ثٌىفجءر .4 ثٌقشثس٠ز ثٌّىذق١ز ٌٍّقشن ثٌغٕجةٟ صىْٛ ِغج٠ٚز صمش٠ذج ٌم١ّضٙج .ػٕذ ثٌؼًّ دٛلٛد د٠ضي فمػ إْ أػٍٝ ل١ّز ٌٍعغػ ثأللصٝ ٌألعطٛثٔز فٟ ثألفّجي .5 ثٌّٕخفعز ٠قذط ػٕذ ػًّ ثٌّقشن دٛلٛد د٠ضي فمػ، ف١ّج صىْٛ أػٍٝ ل١ّز ٌٗ ػٕذ ػًّ ثٌّقشن دؤفّجي ِضٛعطز ػٕذ ِٓ ٚلٛد ثٌذ٠ضي، أِج ػٕذ % 60 ث40ٌٝٔغخ ِقصٛسر د١ٓ فًّ لش٠خ ِٓ ثٌقًّ ثٌىٍٟ فجْ أػٍٝ ل١ّز ٌٍعغػ ثأللصٝ .دثخً ثالعطٛثٔز ٠قذط ػٕذ ثلً ٔغذز ٚلٛد د٠ضي ،1جذول .يىاصفاخ انًحرك انًستخذو في انثحث technical characteristics prodit s.a.s. manufacture otto or diesel, four strokes -cycle 1 vertical -number of cylinder 90 mm -diameter 85 mm -stroke 541 cm3 -swept volume 4÷17.5 -compression ratio 4 kwat 2800 rpm -max. power 28nm at 1600rpm -max torque -water cooled 500÷3600 rpm (otto cycle) -no load speed rang 1200÷3600 rpm (otto cycle) -load speed range 54⁰ before t.d.c. -intake start 22⁰ after t.d.c. -intake end 22⁰ before t.d.c. -exhaust start 54⁰ after t.d.c. -exhaust end 10⁰ (spark ignition) -fixed spark advance 8 10 12 14 16 18 20 22 0 20 40 60 80 d e la y t im e diesel fuel energy rate n=1000 rpm, it=26 btdc, cr=16.21 bmep=652 kpa bmep=521 kpa bmep=433 kpa bmep=315 kpa bmep=208 kpa bmep=0 kpa (2012) 103-97، انصفحح 2، انعذد8يجهح انخىارزيي انهُذسيح، انًجهذ يعٍ جُاٌ تشير 102 قائًح انريىز انًستخذيح atdc دؼذ ثٌٕمطز ث١ٌّضز ثٌؼ١ٍج btdc لذً ثٌٕمطز ث١ٌّضز ثٌؼ١ٍج ºca دسؽجس ِٓ ػّٛد ثٌّشفك cr ٔغذز ثألٔعغجغ far ٔغذز ثٌٛلٛد ثٌٝ ثٌٙٛثء oit ًصٛل١ش ثٌقمٓ ثألِغ bmep ِضٛعػ ثٌعغػ ثٌّىذقٟ ثٌفؼجي bp ثٌمذسر ثٌّىذق١ز bsfc ٟأعضٙالن ثٌٛلٛد ثٌٕٛػٟ ثٌّىذق انًصادر .6 [1] salariya, k s, sethi, v, exhaust analysis and performance of a single cylinder diesel engine run on dual fuels, ie (i) journal, vol.85, 2004. [2] karim, g.a. and klat, s.r. and moore, n.p.w., knock in dual fuel engine, proc. inst. of mech. eng., vol. 181, pt.1, 1996. [3] karim, g.a., a review of combustion processes in the duel fuel engines, the gas diesel engine, prog. energy combustion sci. j., vol. 1, 1989. [4] annand, w.j.d., heat transfer in the cylinder s of reciprocating internal combustion engine, ph.d. thesis, university of manchester, england, 1992. [5] yamin, a. a., servastava, r. m., performance compression of lpg and gasoline as fuels of ambassador car engine, ie(i) journal-mc, vol. 84, 2003. [6] mockus, s., sapragonas, j., stonys, a., pukalskas, s., analysis of exhaust gas composition of internal combustion engines using lpg, journal of environmental engineering and landscape management, vol. 15, n0. 1, 2006 [7] song, s and hill, p.g., duel fueling of a prechamber diesel engine with natural gas, sae paper no.991115, 1999. [8] benea b c and soica a o, researches regarding using lpg on diesel engine, fascicle of management and technological engineering, vol. vi (xvi), 2007. [9] karim g a, an examination of some measures for improving the performance of gas fuelled diesel engine at light load. sae transactions, 912366, 1991. [10] qi d h, bian y zh, ma zh y, zhang ch h and liu sh q, combustion and exhaust emission characteristics of a compression ignition engine using liquefied petroleum gasdiesel blended fuel. energy conversion and management, vol. 48, no.2, pp: 500 -509, 2007. [11] sethi v p and salariya k s, exhaust analysis and performance of a single cylinder diesel engine run on dual fuels, ie (i) journal.mc vol. 85, april, 2004. maan janan basheer al-khwarizmi engineering journal, vol.8, no.2, pp 97-103 (2012) 103 study of effect of diesel fuel energy rate in duel fuel on performance of compression ignition engine maan janan basheer department of machines and equipment engineering /university of technology abstract the aim of this work is to study the effect of diesel fuel percentage on the combustion processes in compression ignition engine using dual – fuel (diesel and lpg). the brake thermal efficiency increased with the increase of diesel fuel rate at low loads, and decreased when load increased. to get sufficient operation in engine fueled with dual fuel, it required sufficient flow rate of diesel fuel, if the engine fueled with insufficient diesel fuel erratic operation with miss fire cycles presented. dual-fuel operation at part load showed higher specific fuel consumption than straight diesl operation. at full loads, brake specific fuel consumption of duel fuel engine approaches that for diesel fuel values. shoaf, w dr.ahmed jawad /al-khwarizmi engineering journal, vol.2, no.1,pp 85-97 (2006) 58 al-khwarizmi engineering journal al-khwarizmi engineering journal, vol.2, no.1,pp 85-97, (2006) extraction of chlorophyll from alfalfa plant isam kamal dr.ahmed jawad ali khalid khudair al-jomaily chem. eng. dept biochem. eng. dept chem. eng. dept university of technology khwarizmycollege of eng university of technology university of baghdad (received 5 december 2005; accepted 4 april 2006) abstract: the extraction process of chlorophyll from dehydrated and pulverized alfalfa plant were studied by percolation method. two solvent systems were used for the extraction namely; ethanol-water and hexane-toluene systems . the effect of circulation rate, solvent concentration, and solvent volume to solid weight ratio were studied. in both ethanol water, and hexane-toluene systems it appears that solvent concentration is the most effective variable. keywords: chlorophyll, extraction, percolation, alfalfa 1.introduction chlorophyll, so defined, is a mixture of green pigments, which is always combined by other pigments, principally those of the carotenoid group [1]. alfalfa is usually used as a green plant source for the extraction of chlorophyll because of its availability along all seasons of the year and because of its low price. chlorophyll is relatively labile and during isolation it is necessary to protect it from degradation. as a general precaution, it is advantageous to work in dim light and low temperature to avoid pigment loss[2]. for extraction of high quality chlorophyll, there are many laboratory methods [3-10]. the most popular applied process is the extraction of chlorophyll by hexane or ethanol where both batch (percolation) and continuous processes (cstr) were used [11,12]. no data appeared in literature for the evaluation of process parameters for the extraction of chlorophyll. hence the purpose of this study is to investigate the process parameters for the extraction of chlorophyll from dehydrated alfalfa plant using percolation method. these parameters are namely; circulation rate of solvent, type and concentration of solvent, and volume of solvent to solid weight ratio. different solvent systems were used for the extraction, namely, ethanolwater, and hexane-toluene blend. 2.experimental work material the alfalfa used for extraction was first dried in an oven at 45-500c for 1-2 hours[11]. then the dried alfalfa was dr.ahmed jawad /al-khwarizmi engineering journal, vol.2, no.1,pp 85-97 (2006) 58 finely ground in a ball mill and then screened in a 50-mesh screen[11]. the 50 mesh size cut of alfalfa was used in the extraction experiments. ethanol (95%, near isotropic concentration obtained from atmospheric distillation ) used in ethanol-water system was supplied by general company for drinking and food industry. hexane is supplied by tagi gas plant while toluene (99.9%) was supplied by arabian company for detergents chemicals. 3. description of equipment extraction experiments were carried out in qvf glass rig (fig. 1) [13]. the extractor is a qvf cylindrical vessel of 21 cm in diameter and 58 cm height. in the extractor a cloth pocket is introduced filled with alfalfa. liquid is distributed on the alfalfa pocket by a porous glass distributor. solvents were circulated from a 20 liter qvf spherical vessel. a centrifugal pump(q=2160 l/h, head = 3m) were used for solvent extraction. a qvf rota meter (0-400 l/h) was used to control the volumetric flow rate of solvent. the batch distillation system for the recovery of chlorophyll and solvents consists of qvf cylindrical vessel, qvf condenser with double coil of 8 cm in diameter and 50 cm high. a 148 kw electrical heater (stabilag, england) was used in batch distillation. a digital temperature indicator controller was used for controlling temperature in batch distillation within 0 – 400 0c. a chiller (mgw lauda) was used for cooling of water necessary for the condensation of solvent vapors in the condenser. a ball mill (siemens) was used for grinding dehydrated alfalfa meal. 4. experimental procedure for the extraction system, the cloth pocket is filled with 1 kg of pulverized dehydrated alfalfa meal and then placed in the extraction cylindrical vessel. the spherical circulating vessel is filled with a certain volume of solvent. before starting the experiments the solvent is heated to 350c and kept constant at this temperature throughout the experiments using a temperature controller in order to compare the different operation conditions at constant temperature . then the circulating pump was switched on to circulate the solvent through the extractor and the spherical vessel. a needle valve was used for adjusting the volumetric flow rates of solvent at the desired value as indicated on the rotameter. the circulation of solvent was continued for a maximum duration of 3 hours. every fifteen minutes, a sample was taken for the solvent by a pipette. the concentration of chlorophyll in the sample was measured by atomic absorption spectrophotometer at the university of technology by measuring the ratio of absorbencies at 654 nm (a645) and 663 nm (a663). the concentration can then be calculated using the following equation[ 17 ]: total chlorophyll (mg/l) = 20.2 a645 + 8.02 a663 -----------------(1) when the concentration of chlorophyll remains constant, the extraction experiment was stopped. batch distillation is used for the concentration of the product and for the recovery of solvent. the temperature of distillation of solvents must not affect the color of the solute (chlorophyll). this temperature was 900c for ethanol-water system and 80 0c for hexane-toluene system. this process for the separation of concentrated chlorophyll and recovery of the solvent were proceeded for 5-6 hours. 5. results & conclusion the effect of operating variables on the extraction rate of chlorophyll for dr.ahmed jawad /al-khwarizmi engineering journal, vol.2, no.1,pp 85-97 (2006) 58 ethanol-water and hexane-toluene systems from alfalfa were studied in this work. the percentage of extracted chlorophyll was calculated using the following relationship : amount of chlorophyll dissolved % extracted chlorophyll = --------------------------------------------------- total amount of chlorophyll in dehydrated alfalfa meal 6. the effect of circulated rates of solvent both system (figs. 2 and 3 ), the percentage of extracted chlorophyll increased with increasing circulation rates of solvent. the two main steps of mass transfer in the extraction process are diffusion of the fluid through solid and diffusion through film surrounding solid particles. since solid particles are pulverized, the resistance to mass transfer by molecular diffusion of the solute from solid internal pores to the film surrounding solid particles will be smaller than the solute mass transfer across the film surrounding the particles to the solvent bulk. hence, the expected rate controlling step is the diffusion of solute through film surrounding solid particles to the solvent bulk. it is well known that extraction efficiency increased with increasing velocity of solvent. this phenomena is applicable for laminar flow (131 < re <431) , since in turbulent flow increasing of velocity of solvent have little effect on extraction rate [ 14 ]. in our case, the flow inside extractor is streamline (laminar), so the effect of velocity is noticed. 7. the effect of solvent concentration in ethanol-water system (fig. 4 ), it can be noticed that the percentage of extracted chlorophyll increased as concentration of ethanol increased. this behavior can be explained as follows; higher concentration of ethanol means lower viscosity of solvent. this will lead to higher wetting of solids and hence increase extraction rates[16]. it also appeared in fig. 3 that lower concentration of ethanol (50%) indicates lower extraction efficiency of chlorophyll. hence, the minimum concentration used for the extraction of chlorophyll must be not less than 70%. this result is in agreement with the conclusion of othmer [15]. the effect of blending of hexane and toluene on the percentage of chlorophyll extract is shown in fig. 5. the percentage of extracted chlorophyll when using a pure hexane did not exceed 77%. at toluene concentration of less or equal to 21% by volume, the extraction efficiency is increased, while the extraction efficiency is decreased at toluene concentration greater than 21% [13]. this behavior can be explained as follows[9] ; the phytol group (c20h39oh) is a long-chain alcohol separated from the structure of chlorophyll and when the extraction process started, the phytol group is freely mobile in the liquid phase. this layer of phytol is impeded the nonpolar solvent (hexane) to penetrate through the chlorophyll [9]. but when a certain volume of toluene (21%) is blended with hexane, a reaction occurs between toluene and phytol group which produced aromatic alcohol (benzyl alcohol). this aromatic is considered a more stronger solvent than pure hexane. on increasing the percentage of toluene above 21%, the physical properties of toluene as a solvent will be the controlling step, hence the extraction efficiency dropped. dr.ahmed jawad /al-khwarizmi engineering journal, vol.2, no.1,pp 85-97 (2006) 55 8. the effect of solvent volume to solid weight ratio as shown in figs. 6,7, the percentage extracted chlorophyll increased with increasing volume of solvent for both system. this behavior could be explained as follows; as the volume of the solvent increased, the concentration difference (which is one of the most effective driving forces for mass transfer) will be increased and hence the extraction efficiency will be increased. but on increasing volume of solvent with respect to solid weight, the cost of solvent recovery will be increased with respect to volume of the distillation unit and the power applied. 9. conclusion 1the extraction rate of chlorophyll increased when; increasing the circulation rate of solvent in the two systems, increasing the concentration of ethanol, blending less than 21% of toluene in toluene-hexane system, and increasing solvent volume to solid weight ratio. 2for ethanol water system, the effect of ethanol concentration on percentage of extracted chlorophyll was found to be most effective compared to circulation rate of solvent and volume of solvent to weight ratio. while the minimum concentration of ethanol used in the extraction must not be less than 70%. 3in hexane-toluene system, the effect of hexane toluene blend is the most effective parameter on percentage of extracted chlorophyll compared to the effect of circulation rates and solvent volume to solid weight ratio. while the optimum concentration of blend was found to represent 21% toluene and 79% hexane. 10. references 1dobrota, g.l., katz, j.j., thomas, m.r., "separation of chlorophyll pigment from plants", agr. food chem. 8, 4, 3 (1987). 2mcfeeters, p.s., and kempster, h.l., "the chlorophyll", j.plant physiol. 17, 3, 600618(1971). 3schertz, f.m., "isolation of chlorophyll, carotene and xanthophylls by improved methods", ind. eng. chem. 30, 2, 1073-1075(1938). 4 iriyama, k., ogura, n., takamiya, a., " a simple method for extraction and partial purification of chlorophyll from plant material, using dioxane", j.biochem. 76, no.4, 901904(1974). 5shoaf, w.t. and b.w. lium, " improved extraction of chlorophyll a and b from algae using dimethyl sulfoxide", limnol. oceanogr. 21, 926 928 (1976). 6hiscox, j.d. and g.f. israaelstan. "a method for the extraction of chlorophyll from leaf tissue without maceration". can. j. bot. 57, 1332—1334 (1979). 7 johnson, a. b., "chlorophyll extraction techniques", in: "methods in plant physiology", editors: e. will and f. bill, cambridge university press, cambridge, 25-30(1989). 8agar, i.t., s. cetiner, j.m. garcia and j. streif, "a method of chlorophyll extraction from dr.ahmed jawad /al-khwarizmi engineering journal, vol.2, no.1,pp 85-97 (2006) 58 fruit peduncles: application to red currants", tr. j. of agricultural and forestry 18, 209-212 (1994). 9eigenberg, k.e., croasmun, w.r., "extraction of chlorophyll from chlorophyllproteins", j.biochim. biophys. acta, 642, 3, 438(1981). 10wood, l. w. , "chloroformmethanol extraction of chlorophyll a", can. j. fish. aquat. sci. 42, 38-43(1985). 11judah, m.a., burdick, e.m., and robert, g.c., "chlorophyll, by solvent extraction", ind& eng. chem. 46, 11, 2262-2271(1954). 12shearon, w., gee, d.f., "caroten and chlorophyll commercial chromatographic production", ind. & eng. chem. 41, 2, 218-226(1949). 13 al-jomaily, k.k., "optimization of chlorophyll extraction from alfalfa meal", m.sc. thesis, university of technology, baghdad (2000). 14 sungtan, c., kweiliang, s., and chungliou, "liquid-solid mass transfer in extractor", chem. eng. 38, dec., 1722(1988). 15davies, j.t., and rideal, e.k., "interfacial phenomena", academic press, inc., 2nd edition (1961). 16othmer, k., "encyclopedia of chemical technology", 2nd edition, john wiely and sons, inc., vol.5, 339(1964). 17harborne, j.b., "photochemical methods", chapman and hall, london, 1973. dr.ahmed jawad /al-khwarizmi engineering journal, vol.2, no.1,pp 85-97 (2006) 89 ( 1 ) d i s t r i b u t e r ( 2 ) c o n d e n s e r ( 3 ) c y l i n d r i c a l v e s s e l ( 4 ) r o t a m e t e r ( 5 ) c e n t r i f u g a l p u m p ( 6 ) d i g i t a l t e m p . c o n t r o l l e r ( 7 ) c h i l l e r ( 8 ) s t o r a g e t a n k ( 9 ) s t o r a g e t a n k ( 1 0 ) h e a t e r ( 1 1 ) s a m p l i n g p o i n t ( 1 2 ) s e n s o r s ( 1 3 ) s p h e r i c a l v e s s e l ( 1 4 ) c l o t h p o c k e t 7 8 9 1 3 1 4 2 5 f i g u r e ( 1 ) : g e n e r a l f l o w d i a g r a m o f e x p e r i m e n t a l r i g . 6 1 0 4 3 1 1 1 1 2 dr.ahmed jawad /al-khwarizmi engineering journal, vol.2, no.1,pp 85-97 (2006) 89 f ig u re ( 2 ) : e ff e c t o f c ir c u la ti o n r a te s o n c h lo ro p h y ll e x tr a c ti o n w it h 7 2 % e th a n o l (v o l. o f s o lv e n t/ w t. o f s o li d s : 1 1 /1 ). 0 1 0 2 0 3 0 4 0 5 0 6 0 0 2 0 0 0 4 0 0 0 6 0 0 0 8 0 0 0 1 0 0 0 0 1 2 0 0 0 1 4 0 0 0 1 6 0 0 0 e x tr a c ti o n t im e , s e c chlorophyll extracted (wt%) c ir c u la ti o n ra te = 0 .1 4 c u .m /h c ir c u la ti o n r a te = 0 .2 4 c u .m /h c ir c u la ti o n r a te = 0 .3 4 c u .m /h dr.ahmed jawad /al-khwarizmi engineering journal, vol.2, no.1,pp 85-97 (2006) 89 f ig u re (3 ) : e ff e c t o f s o lv e n t c o n c e n tr a ti o n o n c h lo ro p h y ll e x tr a c ti o n w it h e th a n o l s o lu ti o n a t a c ir c u la ti o n r a te o f 0 .2 4 c u .m /h ( v o l. o f s o lv e n t/ w t. o f s o li d : 1 1 /1 ). 0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 0 1 0 0 0 2 0 0 0 4 0 0 0 6 0 0 0 8 0 0 0 1 0 0 0 0 1 2 0 0 0 1 4 0 0 0 e x tr a c ti o n t im e , s e c chlorophyll extracted (wt%) s o lv e n t c o n c e n tr a ti o n = 5 0 % s o lv e n t c o n c e n tr a ti o n = 7 2 % s o lv e n t c o n c e n tr a ti o n = 9 4 % dr.ahmed jawad /al-khwarizmi engineering journal, vol.2, no.1,pp 85-97 (2006) 89 f ig u re ( 4 ) : e ff e c t o f v o l. o f s o lv e n t/ w t. o f s o li d r a ti o o n c h lo ro p h y ll e x tr a c ti o n w it h 7 2 % e th a n o l a t a c ir c u la ti o n r a te o f 0 .2 4 c u .m /h . 0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 0 2 0 0 0 4 0 0 0 6 0 0 0 8 0 0 0 1 0 0 0 0 1 2 0 0 0 1 4 0 0 0 e x tr a c ti o n t im e , s e c chlorophyll extracted (wt%) v o l. s o lv e n t/ w t. s o lid = (8 /1 ) v o l. s o lv e n t/ w t. s o lid = (1 1 /1 ) v o l. s o lv e n t/ w t. s o lid = ( 1 4 /1 ) dr.ahmed jawad /al-khwarizmi engineering journal, vol.2, no.1,pp 85-97 (2006) 89 f ig u re ( 5 ) : e ff e c t o f c ir c u la ti o n r a te o n c h lo ro p h y ll e x tr a c ti o n w it h h e x a n e -t o lu e n e b le n d ( 7 9 % h e x a n e ) (v o l. o f s o lv e n t/ w t. o f s o li d : 1 1 /1 ). 0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 0 1 0 0 0 2 0 0 0 4 0 0 0 6 0 0 0 8 0 0 0 1 0 0 0 0 1 2 0 0 0 1 4 0 0 0 e x tr a c ti o in t im e , s e c chlorophyll extracted (wt%) c ir c u la ti o n r a te = 0 .1 4 c u .m /h c ir c u la ti o n r a te = 0 .2 4 c u .m /h c ir c u la ti o n r a te = 0 .3 4 c u .m /h dr.ahmed jawad /al-khwarizmi engineering journal, vol.2, no.1,pp 85-97 (2006) 88 f ig u re ( 6 ) : e ff e c t o f s o lv e n t c o n c e n tr a ti o n o n c h lo ro p h y ll e x tr a c ti o n w it h h e x a n e t o lu e n e b le n d a t a c ir c u la ti o n r a te o f 0 .2 4 c u .m /h . 0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 0 1 0 0 0 2 0 0 0 4 0 0 0 6 0 0 0 8 0 0 0 1 0 0 0 0 1 2 0 0 0 1 4 0 0 0 e x tr a c ti o in t im e , s e c chlorophyll extracted (wt%) s o lv e n t c o n c e n tr a ti o n = 1 0 0 % t o lu e n e s o lv e n t c o n c e n tr a ti o n = 1 0 0 % h e x a n e s o lv e n t c o n c e n tr a ti o n = 7 9 % h e x a n e dr.ahmed jawad /al-khwarizmi engineering journal, vol.2, no.1,pp 85-97 (2006) 88 f ig u re ( 7 ) : e ff e c t o f v o l. o f s o lv e n t/ w t. o f s o li d r a ti o o n c h lo ro p h y ll e x tr a c ti o n w it h h e x a n e -t o lu e n e b le n d ( 7 9 % h e x a n e ) a t a c ir c u la ti o n r a te o f 0 .2 4 c u .m /h . 0 2 0 4 0 6 0 8 0 1 0 0 1 2 0 0 2 0 0 0 4 0 0 0 6 0 0 0 8 0 0 0 1 0 0 0 0 1 2 0 0 0 1 4 0 0 0 e x tr a c ti o in t im e , s e c chlorophyll extracted (wt%) v o l. s o lv e n t/ w t. s o lid = (8 /1 ) v o l. s o lv e n t/ w t. s o lid = (1 1 /1 ) v o l. s o lv e n t/ w t. s o lid = (1 4 /1 ) dr.ahmed jawad /al-khwarizmi engineering journal, vol.2, no.1,pp 85-97 (2006) 88 وروفيل من نبات الجتأستخالص الكل د.عصام كامل د.احمد جواد علي خالد خضير قسم الهندسة الكيمياوية قسم الهندسة الكيمياوية األحيائية قسم الهندسة الكيمياوية الجامعة التكنلوجية يكلية هندسة الخوارزم الجامعة التكنلوجية جامعة بغداد :الخالصة تم في هذا البحث دراسة عملية أستخالص الكلوروفيل من الجت المجفف والمطحون بطريقة التغلغل. تم أستخدام نظامين منن تولوين . تم دراسة تنثثير مدندل التندويرر تركينم المنذي -ماء ومنظومة هكسان-المذيبات لألستخالص وهي منظومة أيثانول المستخدمة . في كال المنظومتين تم التوصل الى أن تركينم المنذي هنو الدنصنر و نسبة حجم المذي الى ومن المادة الصلبة األكثر تثثيرا. characterization of delamination effect on free vibration of composite laminates plate using high order shear deformation theory al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 8, no. 1,pp 18 -26 (2012) color image denoising using stationary wavelet transform and adaptive wiener filter iman m.g. alwan department of computer science /college of education for women /university of baghdad email: ainms_66@yahoo.com (received december 2011; accepted january 2012) abstract the denoising of a natural image corrupted by gaussian noise is a problem in signal or image processing. much work has been done in the field of wavelet thresholding but most of it was focused on statistical modeling of wavelet coefficients and the optimal choice of thresholds. this paper describes a new method for the suppression of noise in image by fusing the stationary wavelet denoising technique with adaptive wiener filter. the wiener filter is applied to the reconstructed image for the approximation coefficients only, while the thresholding technique is applied to the details coefficients of the transform, then get the final denoised image is obtained by combining the two results. the proposed method was applied by using matlab r2010a with color images contaminated by white gaussian noise. compared with stationary wavelet and wiener filter algorithms, the experimental results show that the proposed method provides better subjective and objective quality, and obtain up to 3.5 db psnr improvement. keywords: stationary wavelet transform (swt), adaptive wiener filter, thresholding. 1. introduction images acquired through sensors [chargecoupled device (ccd)] cameras may be contaminated by noise sources. image processing technique also corrupts image with noise, leading to significant reduction in quality. traditionally, linear filters (mean, median, and wiener filter) are used for removing noise from images, but it blurs data [1]. it is well known that wavelet transform is a signal processing technique which can display the signals on in both time and frequency domain. wavelet transform is superior approach to other time-frequency analysis tools because its time scale width of the window can be stretched to match the original signal, especially in image processing studies. this makes it particularly useful for nonstationary signal analysis, such as noises and transients. for a discrete signal, a fast algorithm of discrete wavelet transform (dwt) is multiresolution analysis, which is a nonredundant decomposition [2]. one of the most popular method consists of thresholding the wavelet coefficients (using hard threshold or the soft threshold) as introduced by donoho [3]. elyasi and zarmehi [4] proposed several methods of noise removal from degraded images with gaussian noise by using adaptive wavelet threshold (bayes shrink, modified bayes shrink and normal shrink). jacob and martin [5] performed wiener filtering on the wavelet coefficients to denoise an image degraded by an additive white gaussian noise (awgn). jin et. al. [6] considered the adaptive wiener filtering of noisy images and image sequences. they began by using an adaptive weighted averaging (awa) approach to estimate the secondorder statistics required by the wiener filter and extended the awa concept to the wavelet domain and that gained 0.5 db over traditional wavelet wiener filter. the drawback of nonredundant transform is their noninvariance in time/space; i.e., the coefficients of a delayed signal are not a timeshifted version those of the original signal. the stationary wavelet transform (swt) was introduced in 1996 to make the wavelet decomposition time invariant [7]. this improves mailto:ainms_66@yahoo.com iman m.g. alwan al-khwarizmi engineering journal, vol. 8, no. 1,pp 18 26 (2012) 19 the power of wavelet in signal de-noising. this paper exploits the benefits of stationary wavelet transform in suppressing noise at high frequencies and wiener filter to suppress noise in low frequency bands. the proposed algorithm is divided into two steps. after taking swt to the noisy image, soft thresholding method is applied to the details subbands; then a transformed image is generated from approximation subband only while the other subbands are made equal to zero, applying inverse swt to the generated 2-d array, then applying the adaptive wiener filter, to remove the residual noise in the low frequency band. after that the approximation band is returned by applying swt to the denoised signal, the resulted approximation subband is grouped with the thresholded subbands, applying inverse swt to obtain the denoised image. the proposed method is compared with the other two traditional denoising methods, namely swt and wiener filter, to validate the denoised characteristics of this method. 2. stationary wavelet method this section presents the basic principals of the swt method. in summary, the swt method can be described as follows. at each level, when the high-pass and low-pass filters are applied to the data, the two new sequences have the same length as the original sequences. to do this, the original data is not decimated. however, the filters at each level are modified by padding them out with zeros. supposing a function )(xf is projected at each step j on the subset jv )(.... 0123 vvvv  . this projection is defined by the scalar product kjc , of )(xf with the scaling function )(x which is dilated and translated.  )(),( ,, xxfc kjkj  ... (1) )2(2)(, kxx jj kj    ... (2) where )(x is the scaling function, which is a low-pass filter. kjc , is also called a discrete approximation at the resolution j2 . if )(x is the wavelet function, the wavelet coefficients are obtained by   )2(2),(, kxxf jj kj  ...(3) kj , is called the discrete detail signal at the resolution j2 . as the scaling function )(x has the following property:   n nxnh x )()() 2 ( 2 1  h (n) represents the scaling coefficients. kjc ,1 can be obtained by direct computation from kjc , .     n n njkj nxng x andcknhc )()() 2 ( 2 1 )2( ,,1  ...(4) g (n) represents the wavelet coefficients. the scalar products   )2(2),( )1()1( , kxxf jj kj  are computed with   n njkj ckng ,,1 )2( ...(5) equations (4) and (5) are the multiresolution algorithm of the traditional dwt. in this transform, a downsampling algorithm is used to perform the transformation. that is, one point out of two is kept during transformation. therefore, the whole length of the function will be reduced by half after the transformation. this process continues until the length of the function becomes one. however, for stationary or redundant transform, instead of downsampling, an upsampling procedure is carried out before performing filter convolution at each scale. the distance between samples is increased by a factor of two from scale to the next. kjc ,1 is obtained by    l lkjkj jclhc 2,,1 )( ...(6) and the discrete wavelet coefficients    l lkjkj jclg 2,,1 )( ...(7) the redundancy of this transform facilitates the identification of salient features in a signal, especially for recognizing the noises. this is the transform for one-dimensional signal. for a twodimensional image, we separate the variables x and y and have the following wavelets. iman m.g. alwan al-khwarizmi engineering journal, vol. 8, no. 1,pp 18 26 (2012) 20 — vertical wavelet: )()(),(1 yxyx   — horizontal wavelet: )()(),(2 yxyx   — diagonal wavelet: )()(),(3 yxyx   thus, the detail signal is contained in three subimages [8].         x y j l l yxkjyxyxj llclhlgkk ),()()(),( 2, 1 1 ..(8)         x y j l l yxkjyxyxj llclglhkk ),()()(),( 2, 2 1 ...(9)         x y j l l yxkjyxyxj llclglgkk ),()()(),( 2, 3 1 ...(10) 3. implementation of the proposed algorithm this section, describes the method for computing the various parameters used to compute the threshold and the image denoising algorithm. the swt is used for the recovery of the corrupted image with adaptive wiener filter. wiener filter is a minimum mean square error filter. it has capabilities of handling both the degradation function as well as the noise. the wiener filter in the fourier domain is given by the expression: ),( ),( ),( ),( ),( ),( 2 * vug vus vus vuh vuh vuf f                  ... (11) where h (u, v) is the degraded function ),(* vuh is the complex conjugate of h(u,v) ),(),(),( *2 vuhvuhvuh  2 ),(),( vunvus  is the power spectrum of the noise. 2 ),(),( vufvus f  is the power spectral density (psd) of the undegraded image. g(u,v) is the fourier transform of the degraded image. when wiener filtering is performed on small blocks of an image at a time; the method is called local wiener filtering. in this method, the psd of the undegraded image is estimated for each block. this calculated psd is then used in the expression of the wiener filter. thus, the local statistics are also accounted for in the calculation of the wiener filtered image. images with many edges are handled much well by the local wiener filter than the global wiener filter. we used a window of size 3 x 3 in the calculation of the local [9] the threshold value ( nst ), which is adaptive to different subband characteristics, is calculated by normal shrink [4].    y n nst   2 ...(12) where scale parameter  is calculated once for each scale using )/log( jlk ...(13) where kl is the length of the subband at the thk scale, j is the total number of decompositions and ^ y is the standard deviation of the subband. noise variance 2^ n is estimated in equation (14), using the robust and accurate median estimator of the suddand . 6745.0 )(2^ i n ymedian  ...(14) iy each subband where 0.6745 is the experiential value [10]. we have actually applied wiener filter for the image obtained from (ll subband only while maintaining other subbands equal to zero) in the spatial domain by applying inverse stationary wavelet transform in order to remove the residual noise in the low frequency subband in addition for applying softthreshold for lh, hl, hh subbands, so it offered superior results in denoising. soft thresholding deletes the coefficients under the threshold, but scales the ones that are left. there are different ways of scaling. the general soft shrinkage rule is defined by:  ))(sgn()(  www ...(15) where  is the threshold and the plus sign indicates only the coefficients that are above the threshold are considered. the proposed algorithm is described in this section; it is applied for each (red, green, and blue) band separately. iman m.g. alwan al-khwarizmi engineering journal, vol. 8, no. 1,pp 18 26 (2012) 21 it consists of the following steps: 1read the noisy color image (contaminated with white gaussian noise) 2for each (r, g, b) band apply swt (one level of decomposition) estimate the noise variance in the noisy image using equation (14) calculate the scale parameter  using equation (13). for each detail subband, compute the standard deviation and threshold nst using equation (12). apply soft threshold to the subbands lh1, hl1, hh1. 3reconstruct a new image from ll1 subband only while making other subbands equal to zero, by applying inverse stationary wavelet transform. 4apply an adaptive wiener filter to the reconstructed image in spatial domain. 5reapplying swt to the resultant image of step 4. 6extract the approximation subband from step 5 denoted by ll2, then grouping it with the thresholded subbands denoted by ( ^ lh , ^ hl , and ^ hh ) of step 2 as ll, lh, hl, and hh subbands. 7apply inverse stationary wavelet transform, to get the denoised image. figure (1) shows the schematic of this approach fig.1. a schematic of the proposed denoising algorithm. 4. experimental results the experimental evaluation is performed on color images of size 256 * 256 pixels at different white gaussian noise levels shown in figure (2). the objective quality of the reconstructed image is in terms of the psnr of the three color components ),,{, bgrxx  , which is defined as [9]: )( 255 log10 2 10 xmse psnr  ... (16) where mse (x) is the mean-square-error of the original color component and the estimated one.. the overall psnr is obtained as )()()( 255 log10 2 10 bmsegmsermse psnr   ... (17) the proposed method was implemented using matalab r2010a. the psnr results are shown in table (1). swt ll1 lh1 hl1 hh1 lh 1 hl 1 hh 1 apply soft threshold ll 1 iswt wiener filter swt ll2 lh2 hl2 hh2 iswt denoised image noisy image taking ll from step 2 while other parts equal to zero output of swt (2nx2n) for nxn input image ll2 ^ lh ^ hl ^ hh taking ll2 subband only iman m.g. alwan al-khwarizmi engineering journal, vol. 8, no. 1,pp 18 26 (2012) 22 fig.2. test color images. table 1, psnr of various noisy color images and denoised ones for swt, wiener, and the proposed algorithm. test images noise variance noisy image psnr (db) swt psnr (db) wiener psnr (db) proposed method psnr (db) baboon 0.003 30.06 32.53 32.83 30.28 0.007 26.43 30.84 31.19 29.95 0.010 24.92 29.95 30.27 29.76 0.030 20.38 26.57 26.81 28.64 0.060 17.79 24.26 24.81 27.29 0.080 16.82 23.30 23.72 26.65 0.100 16.17 22.67 23.08 26.07 airplane 0.003 30.01 34.91 35.71 33.14 0.007 26.42 32.21 33.09 32.43 0.010 24.93 31.04 31.09 32.04 0.030 20.76 27.35 27.71 30.27 0.060 18.29 24.84 25.06 28.19 0.080 17.28 23.75 24.00 27.21 0.100 16.56 22.99 23.25 26.35 house 0.003 30.01 34.46 35.55 34.06 0.007 26.38 32.21 32.94 33.11 0.010 24.88 31.04 31.70 32.63 0.030 20.44 27.35 27.44 30.48 0.060 17.86 24.84 24.97 28.64 0.080 16.90 23.75 24.00 27.70 0.100 16.20 22.99 23.31 26.95 lena 0.003 30.04 35.55 36.25 34.87 0.007 26.48 32.72 32.72 34.04 0.010 24.97 31.44 31.44 33.49 0.030 20.54 27.24 27.24 31.04 0.060 17.96 24.72 24.72 28.81 0.080 16.99 23.69 23.69 27.71 0.100 16.25 22.92 22.92 26.96 pepper 0.003 30.14 35.50 36.44 34.82 0.007 26.57 32.63 32.63 33.67 0.010 25.05 31.26 31.26 33.07 iman m.g. alwan al-khwarizmi engineering journal, vol. 8, no. 1,pp 18 26 (2012) 23 0.030 20.72 27.25 27.25 30.58 0.060 18.18 24.73 24.73 28.37 0.080 17.17 23.65 23.65 27.20 0.100 16.43 22.82 22.82 26.29 mona liza 0.003 30.33 33.23 33.91 30.14 0.007 26.68 30.90 31.91 29.36 0.010 25.21 29.90 30.84 28.48 0.030 20.81 26.45 26.89 27.46 0.060 18.26 24.11 24.32 25.99 0.080 17.26 23.22 23.31 25.25 0.100 16.50 22.38 22.60 24.55 watch 0.003 30.10 36.39 35.92 35.72 0.007 26.57 33.47 34.20 34.85 0.010 25.10 32.11 33.25 34.25 0.030 20.73 27.88 29.80 31.59 0.060 18.18 25.22 27.36 29.04 0.080 17.19 24.14 26.36 27.90 0.100 16.47 23.26 25.49 26.92 flower 0.003 30.24 35.67 35.33 34.59 0.007 26.66 33.01 33.60 33.69 0.010 25.17 31.79 32.65 33.19 0.030 20.68 27.57 29.18 30.64 0.060 18.11 24.91 26.77 28.39 0.080 17.12 23.89 25.90 27.33 0.100 16.40 23.07 25.11 26.47 from the results we can find that the psnr of the proposed method offers superior improvement over swt based method and wiener filter method at middle and high values of noise with smoothing edges of the image. at low values of noise the proposed method offers poorer response because the levels of noise are very low at low band frequencies so the effect of wiener filtering for the reconstructed images from ll subband of the swt step is not effective. at middle and high levels of noise, the ll subband of swt step is more attacked by noise values, so the effect of wiener filtering is more noticeable. figure (3) shows the results of each denoising method for three testing images (pepper, airplane, flower) for noise variance (0.1, 0.06. 0.08). also the results of the proposed algorithm, for gray scale images (pepper and house) were compared with the results of the proposed methods of [4] in term of snr (signal to noise ratio) which was adopted in this paper.                           yx yx yxxyxx yxx snr , 2 ^ , 2 ),(),( ),( 10log10 ...(18) where ),( yxx and ),( ^ yxx are the original image and denoised image. table (2) shows the comparison of the proposed method with results of [4] in which modified bayes shrink was proposed. from the comparison table we can notice that the results of the proposed method are slightly better than modified bs in [4]. iman m.g. alwan al-khwarizmi engineering journal, vol. 8, no. 1,pp 18 26 (2012) 24 noisy image, variance=0.1 denoised (proposed method) denoised (wiener filter) denoised (swt) noisy image, variance=0.08 denoised (proposed method) denoised (wiener filter) denoised (swt) fig. 3. results of proposed, wiener filter, and swt denoised images. table 2, snr of the proposed method and modified bs for pepper and house grey images. test images noise variance noisy image snr proposed snr modified bs snr pepper 0.01 14.55 22.49 21.21 0.03 10.08 20.36 18.76 0.06 8.15 18.38 17.51 house 0.003 20.37 24.63 26.46 0.03 10.67 21.41 21.39 0.05 8.76 21.15 20.18 5. conclusion many methods of denoising algorithms based are on wiener filtering on the wavelet coefficients. in this paper a simple and efficient algorithm for adaptive noise reduction is proposed, it combines the adaptive wiener filter in spatial domain and thresholding method in the stationary wavelet transform domain. experimental results show that noisy image, variance=0.06 denoised (proposed method) denoised (wiener filter) denoised (swt) iman m.g. alwan al-khwarizmi engineering journal, vol. 8, no. 1,pp 18 26 (2012) 25 the noise reduction method exhibits better performance in both psnr and visual effect, for middle and high values of white gaussian noise variances, which make the algorithm robust for images attacked by middle and large values of noise. the average increase of psnr of the denoised image with respect to noisy one is approximately (8-9) db, while the improvement with respect to other methods is up to 3.5 db. notation jkc discrete approximation at the resolution j2 h(u,v) degraded function hh high high subband hl high low subband ll low low subband lh low high subband psnr peak signal to noise ratio ),( vus power spectrum of noise ),( vus f power spectral density snr signal to noise ratio nst normal shrink threshold geek letters β scale parameter )(x scaling function )(x wavelet function jk discrete detail signal at the resolution j2 n   standard deviation of noise y   standard deviation of the subband 2 n   noise variance  threshold value y soft thresholded coefficients 6. references [1] patil, a, and singhai, j., ―image denoising using curvelet transform: an approach for edge preservation‖, journal of scientific & industrial research, vol. 69, pp. 34-38., 2010. [2] mallat, s., ―a theory for multiresolution signal decomposition: the wavelet representation,‖ ieee trans. pattern anal. machine intell. vol. 11, pp. 674–693, 1989. [3] donoho, d.l., ―de-noising by softthresholding ―, ieee transactions on information theory, vol. 41, no.3, pp. 613627, 1995. [4] elyasi, i. and zermchi, s., ―elimination noise by adaptive wavelet threshold‖, world academy of science,eng. and tech., vol. 56, pp. 462-465, 2009. [5] jacob and martin, a., ―image denoising in the wavelet domain using wiener filtering‖ ece 533 project, university of wisconsin, fall 2004. [6] jin, f., fieguth, p., winger, l. and jernigan, e., ―adaptive wiener filtering of noisy images and image sequences‖ ieee, icip., vol.2, pp. 349-352, 2003. [7] pesquet, j.c., krim, h. and carfantan, h., ―time-invariant orthonormal wavelet representations,‖ ieee trans. signal processing, vol. 44, pp.1964–1970, 1996. [8] wang, x.h., istepanian, s.h., and song, y.h., ―microarray image enhancement by denoising using stationary wavelet transform‖, ieee trans. on nanobioscience, vol.2, no. 4, pp. 184-189, 2003. [9] gonzalez, r.c., woods, r.e., and eddins, s.l., ―digital image using matlab processing‖, prentice hall, second edition, 2007. [10] johnstone, i.m. and silverman, b.w., ―wavelet threshold estimators for data with correlated noise‖ journal of royal statistical soc., vol. b59, pp. 319-351, 1997. [11] moinuddin, a.a., khan, e. and ghanbari, m., ―an efficient wavelet based embedded color image coding technique using blocktree approach‖, ieee, icip, pp. 1889-1892, 2006. (2012) 26-18، صفحة1، العذد8مجلة الخىارزمي الهىذسية المجلذإيمان محمذ جعفر 26 إزالة الضىضاء مه الصىر الملىوة باستعمال تحىيلة المىيجة المستقرة ومرشح ويىر المتكيّف إيمان محمذ جعفر علىان جايعح تغداد / كهيح انتزتيح نهثُاخ/قسى عهىو انحاسثاخ ainms_66@yahoo.com:انثزيد االنكتزوَي الخالصة انعديد يٍ اندراساخ . هي يٍ انًشاكم في عًهياخ انًعانجح انصىريحgaussianإٌ عًهيح إسانح انضىضاء يٍ انصىر انًتأثزج تضىضاء يٍ َىع اعتًدخ عهى تطثيق تقُيح انعتثح عهى يعايالخ انًىيجح، إٌ يعظى هذِ اندراساخ ركشخ عهى انتشكيم اإلحصائي نًعايالخ انًىيجح وعهى االختيار األيثم ، حيث wienerيقدو هذا انثحث طزيقح جديدج إلسانح انضىضاء تىاسطح ديج تقُيح إسانح انضىضاء تاستعًال تحىيهح انًىيجح انًستقزج ويزشح . نقيًح انعتثح عهى انصىرج انًستزجعح يٍ يعايالخ انتقزية فقظ تيًُا يتى تطثيق تقُيح انعتثح عهى قيى يعايالخ انتفاصيم انتي تى انحصىل wienerيتى تطثيق يزشح عهى صىر يهىَح ويهىثح r2010aنقد تى تُفيذ انطزيقح انًقتزحح تاستعًال تزَايج ياتالب . عهيها تتطثيق تحىيهح انًىيجح انًستقزج ويٍ ثى ديج انُتيجتيٍ . 3.5dbأظهزخ انُتائج تحسيٍ واضح نهصىر وصم نحد . gaussianتضىضاء يٍ َىع default normal template dr. somer m. nacy /al-khwarizmi engineering journal, vol.2, no. 1,pp 15-34 (2006) 15 al-khwarizmi engineering journal al-khwarizmi engineering journal, vol.2, no.1,pp 15-34, (2006) a study of strengthening circular diaphragm by ring-shaped concentric ribs dr. somer m. nacy dr.hikmat al-rawi mohammed m. hasan university of baghdad university of al-anbar university of al-anbar (received 21 september 2005; accepted 4 may 2006) abstract: this paper deals with the determination of stresses and deflections of clamped circular diaphragm strengthened by one or two ring-shaped concentric ribs, under uniform static and dynamic pressures. the simulation has been achieved by using the well-known engineering software finite element package msc/nastran. as a design study, the effect of using a clamped ring, and the effect of using a ring-shaped rib on both surfaces of diaphragm instead of one, has been discussed in this work. to show the effectiveness of this study, results of this work have been compared with published data [1]. in the conclusion, the authors underline the validity of the considered design study, and the optimization of strengthened diaphragms. keywords : diaphragm, nastran, static, dynamic. 1.introduction the diaphragm is the subsystem that distributes lateral load to the perpendicular subsystems and that provides lateral support. diaphragms are treated as horizontal beams. the upper (or lower) surface, which is analogous to the web of a wide-flange beam, is assumed to carry the shear; the edge, which is analogous to the flange, is assumed to carry the flexural stress [2]. several researches have recently been published regarding the stress and deflection characteristics of diaphragms for application to pressure sensors [3,4], microvalves [5], microphones [6] and other acoustic devices. for these devices, the applied load is assumed to be constant over the diaphragm surface [7]. in this work, analytical investigation for a clamped circular diaphragm strengthened by one or two ring-shaped concentric ribs, with builtin stress and large deflections are presented. the advantages of the circular diaphragm consist of good technological, mechanical and measuring properties [1]. in general, analytical and exact variational solutions for diaphragm behavior are desirable because of their dr. somer m. nacy /al-khwarizmi engineering journal, vol.2, no. 1,pp 15-34 (2006) 16 , i.e. ease of use and the insight they provide to the designer. specific geometric effects can be ascertained from these solutions. however, these solutions are generally only applicable for small deflections. numerical techniques, such as finite element analysis, boundary element analysis, and finite difference analysis, can be more accurate in predicting stresses and deflections, especially for large deflections. unfortunately, these techniques generally require more effort to use and may not supply the same insight as analytical or exact variational solutions. the use of plate theory is appropriate for the analysis of diaphragms [7]; therefore, this work has been achieved by using the finite element software package msc/nastran with plate bending and shell elements. as a verification test, and to show the effectiveness of this work, a model similar to one used by a published research [1] has been built in msc/nastran in order to make a comparison between this published research, and the present work. 2.finite element analysis finite element procedures have become an important and frequently indispensable part of engineering analysis and design. finite element computer programs are now widely used in practically all branches of engineering [8]. applications range from deformation and stress analysis of automotive, aircraft, building, and bridge structures to field analysis of heat flux, fluid flow, magnetic flux, seepage, and other flow problems. with the advances in computer technology and cad systems, complex problems can be modeled with relative ease. several alternative configurations can be tried out on a computer before the first prototype is built [9]. the development of finite element methods for the solution of practical engineering problems began with the advent of the digital computer. that is, the essence of a finite element solution of an engineering problem is that a set of governing algebraic equations is established and solved, and it was only through the use of the digital computer that this process could be rendered effective and given general applicability. these two propertieseffectiveness and general applicability in engineering analysis are inherent in the theory used and have been developed to a high degree for practical computations, so that finite element methods have found wide appeal in engineering practice. 3.case studies except the cases used to compare the published data, all of the models used are of the same radius (r = 50mm) and same material (pure, annealed copper) with the following properties [11] : modulus of elasticity, e = 119 gpa. modulus of rigidity, g = 44.7 gpa. poisson’s ratio, ν = 0.326 yield stress, σy = 70 mpa. mass density, ρ = 8.96 g/cm3. fig.(1) shows the schematic view of the base model used (flat diaphragm) with thickness (h = 0.1mm) and radius (r = 50mm). the maximum allowable static pressure that the flat diaphragm can sustain without exceeding the elastic limit may be calculated as [12]: so, as a safety factor (s.f. = 1.5), the uniform pressure used is (p = 250pa) for the static loading, and yy σ 3r 4h p 2 2  pa.373.3p y dr. somer m. nacy /al-khwarizmi engineering journal, vol.2, no. 1,pp 15-34 (2006) 17 this value has been proposed as a peak pressure for the dynamic analysis to work within elastic limit. in order to strength the diaphragm, one or two ring-shaped concentric ribs are used. for this case, two new studies are presented in this work; they are : 1. study the effect of using a ring-shaped rib on both of the upper and lower diaphragm surfaces instead of one surface. 2. study the effect of using clamped ring (built-in with the clamped edges of the diaphragm). to do so, a ring-shaped rib (of the same material as is the diaphragm) with thickness (h = 0.1mm) and radial width (br = 2mm) is used at (25) radial positions, from r = 1mm (bossed material) to r = 49mm (clamped ring) as shown in figures (2-9). the effectiveness of these studies is clearly appeared by making a comparison with the published research [1]. fig.(10) shows the schematic view of the model, which had been used in this published research [1]; where : r = 75mm, h = 4mm, h = 6mm, br = 4mm, r1 = 20mm, r2 = 60mm and the pressure used was (p = 3kpa). the properties of this model were : modulus of elasticity, e = 17.87 mpa., poisson’s ratio, ν = 0.48 to achieve the comparison, similar model has been built in msc/nastran package; and another models with the same properties but with different choices for the dimensions and positions of stiffeners, are used to prove the effectiveness of the design study that has been achieved in this work. for the dynamic analysis, two types of transient loading are used; they are : 1. continuous absolute sine load, at frequency (f = 40hz). 2. absolute sine-pulse load, at the first natural frequency of every case. the dynamic pressure function of these two types of transient loading is :   ftπ250p sin where (f, t) represent the frequency (hz), and time (sec.) respectively; and the transient pressure (p) is measured in (pa). for all the cases used at the dynamic analysis part, damping does not be considered (zero damping). every model used in the finite elements package msc/nastran is divided into triangular and quadrilateral plate bending and shell elements. all of these elements are subjected to uniform pressure and the edges are completely fixed. 4.static analysis the aim of this analysis is to investigate the stresses and deflections of clamped circular diaphragm strengthened by one or more ringshaped ribs. the two studies explained previously are presented here and compared with the published data.  effect of radial position of the ring to show the effect of using ring-shaped ribs on the two surfaces of the diaphragm instead of one surface and the effective use of clamped ring, fifty models are used here at twenty five radial positions of the stiffener. fig.(11) and fig.(12) show the variation in maximum von-mises stresses and maximum deflections dr. somer m. nacy /al-khwarizmi engineering journal, vol.2, no. 1,pp 15-34 (2006) 18 respectively, with the ring position (r) for these cases. thickness of the diaphragm used is (h= 0.1mm.) and dimensions of the rings are (h= 0.1mm. , br = 2mm.).  optimum position : to show the optimum ring position, which gives minimum von-mises stress and maximum deflection, fig.(13) is drawn; were, (s1) represents the maximum von-mises stresses of stiffened diaphragm (ring on one surface only) divided by the maximum von-mises stress of flat diaphragm, (s2) represents the maximum von-mises stresses of stiffened diaphragm (ring on two surfaces) divided by the maximum von-mises stress of flat diaphragm, (s) represents the maximum von-mises stress of stiffened diaphragm (clamped ring) divided by the maximum vonmises stress of flat diaphragm, and (d) represents the maximum deflections of stiffened diaphragm (ring on one or two surfaces) divided by the maximum deflection of flat diaphragm. from these non-dimensional curves, the optimum position appears at (r = 35mm.) for using a ring on one or two surfaces.  optimum case of using two rings : mohammed m. hasan [14] found that the best choice of using two ring-shaped concentric ribs is the use of clamped ring with minimum thickness (h) and a certain radial width (br) and another ring at the optimum position with high thickness and a certain radial width (this would appear clearly from the results of comparison with the published data). so, three cases of using two rings are presented here :  case (1) : clamped ring on one or two surfaces (h= 0.1mm. , br = 10mm.), and another (at the optimum position) on two surfaces (h= 0.5mm. , br = 2mm.).  case (2) : clamped ring on one or two surfaces (h= 0.1mm. , br = 10mm.), and another (at the optimum position) on two surfaces (h= 0.4mm. , br = 10mm.).  case (3) : clamped ring on one or two surfaces (h= 0.1mm. , br = 10mm.) and another (at the optimum position) on two surfaces (h= 0.5mm. , br = 10mm.). the results of these cases with the percentage reduction in maximum vonmises stress are recorded in table (1).  comparison with a published research : as explained previously, a model similar to that of the published research [1] is built in msc/nastran program under the same conditions. the author of this published research did not mention anything about his choice to the dimensions and positions of the two rings he used; the only thing he had explained is that the diaphragm was strengthened by these two ring-shaped concentric ribs. as shown in fig.(10), the two rings used in [1] were of the same dimensions (h= 6mm., br = 4mm.) at radial positions (r1 = 20mm., r2 = 60mm.). so, eleven different cases are used here to choose the optimum positions and dimensions of the stiffeners, and to compare the published data. these cases are :  case (1) : one ring (clamped ring) on one or two surfaces (h= 6mm. , br = 4mm.). dr. somer m. nacy /al-khwarizmi engineering journal, vol.2, no. 1,pp 15-34 (2006) 19  case (2) : one ring (clamped ring) on one or two surfaces (h= 0.6mm. , br = 4mm.).  case (3) : one ring (clamped ring) on one or two surfaces (h= 0.6mm. , br = 10mm.).  case (4) : one ring (at the optimum position) on one or two surfaces (h= 6mm. , br = 4mm.).  case (5) : one ring (at the optimum position) on one or two surfaces (h= 10.5mm. , br = 4mm.).  case (6) : one ring (at the position which gives minimum stress) on one surface ( h= 6mm., br = 4mm.).  case (7) : one ring (at the position which gives minimum stress) on two surfaces ( h= 6mm., br = 4mm.).  case (8) : two rings [ both case (1) and case (4) ].  case (9) : two rings [ both case (1) and case (6) ].  case (10) : two rings [ both case (1) and case (7) ].  case (11) { the optimum choice } : two rings [ both case (3) and case (5) ]. the results of maximum vonmises stresses, maximum deflections and the percentage reduction in maximum von-mises stress of the above cases are shown in table (2). 5.dynamic analysis this part presents the analysis of stresses and deflections of clamped circular diaphragm subjected to dynamic pressure. all of the models used here are of the same dimensions and properties of those used in static part, and subjected to uniform dynamic pressure with two types of transient loading as discussed previously. fig.(14) shows the continuous positive sine function (f = 40 hz., pmax.= 250 pa), which is used for all models, and fig.(15) shows the pulse function with ( f = 72.3hz., pmax.= 250 pa), which is used for the flat diaphragm of the base model.  effect of radial position of the ring : to show the effect of using ring-shaped ribs on the two surfaces of the diaphragm instead of one surface, and the effective use of clamped ring, one hundred cases are used here at twenty five radial positions of the stiffener. fig.(16) and fig.(17) show the variation in maximum von-mises stresses and maximum deflections respectively, with the radial position of the ring (r), for continuous loading (f = 40 hz., pmax. = 250 pa). on the other hand, fig.(18) and fig.(19) show the variation in maximum von-mises stresses and maximum deflections respectively, with the radial position of the ring (r), for sine-pulse loading [f = fn (mode 1), pmax. = 250 pa]. thickness of the diaphragm used is (h= 0.1mm.) and dimensions of the rings are (h= 0.1mm. , br = 2mm.).  optimum position : to show the optimum ring position (which gives minimum von-mises stress and maximum deflection), fig.(20) and fig.(21) are drawn for continuous and pulse loading respectively; were, (s1) represents the maximum von-mises stresses of stiffened diaphragm (ring on one surface only) divided by the maximum von-mises stress of flat diaphragm, (s2) represents the maximum von-mises stresses of stiffened diaphragm (ring on two surfaces) divided by the maximum von-mises stress of flat diaphragm, (s) represents the maximum von-mises stress of stiffened diaphragm (clamped ring) divided by the maximum vonmises stress of flat diaphragm, and (d) dr. somer m. nacy /al-khwarizmi engineering journal, vol.2, no. 1,pp 15-34 (2006) 20 represents the maximum deflections of stiffened diaphragm (ring on one or two surfaces) divided by the maximum deflection of flat diaphragm. from these non-dimensional curves, the optimum position appears at (r = 35mm.) for both continuous and sine-pulse loading (ring on one or two surfaces). 6.conclusions : clamped circular diaphragms may be strengthened by one or more ring-shaped rib in order to reduce the stresses, when a static or dynamic pressure is applied. however, the proper choice to the dimensions and positions of stiffeners may give optimum results; otherwise, random use of these stiffeners may give opposite results. to get minimum stresses and maximum deflections, a ring-shaped rib with a certain dimensions may be used on one or two of the diaphragm surfaces, at a radial position equal to (70%) of diaphragm radius. on the other hand, a ring-shaped rib can be divided into two equal layers to be used on both of the two diaphragm surfaces instead of one, to get better results for a certain choices. the optimum choice for using two ring-shaped concentric ribs is that of using a clamped ring with the favorite thickness and a certain radial width, and another ring with certain dimensions at the optimum position. dr. somer m. nacy /al-khwarizmi engineering journal, vol.2, no. 1,pp 15-34 (2006) 21 h r p b p h h r r h b h /2 h /2 p fig.(1) the schematic view of the base model (flat diaphragm). fig.(2) the schematic view of the bossed diaphragm (one surface). fig.(3) the schematic view of the bossed diaphragm (two surfaces). dr. somer m. nacy /al-khwarizmi engineering journal, vol.2, no. 1,pp 15-34 (2006) 22 br p h r h h r h /2 h /2 br p r br p h h r r h r br h /2 h /2 p fig.(4) the schematic view of the stiffened diaphragm (one ring on one surface). fig.(5) the schematic view of the stiffened diaphragm (one ring on two surfaces). fig.(6) the schematic view of the stiffened diaphragm (clamped ring on one surface). fig.(7) the schematic view of the stiffened diaphragm (clamped ring on two surfaces). dr. somer m. nacy /al-khwarizmi engineering journal, vol.2, no. 1,pp 15-34 (2006) 23 h h r br br p r1 br p h h r br r2 h r br p h /2 h /2 br fig.(8) the schematic view of the stiffened diaphragm (two rings on one surface). fig.(9) the schematic view of the stiffened diaphragm (two rings on two surfaces). fig.(10) the schematic view of the model, which had been used in the published research [1]. dr. somer m. nacy /al-khwarizmi engineering journal, vol.2, no. 1,pp 15-34 (2006) 24 35 36 37 38 39 40 41 42 0 5 10 15 20 25 30 35 40 45 50 position of ring, r [mm] m a x .v o n -m is e s tr e ss [ m p a ] 1.8 1.85 1.9 1.95 2 2.05 2.1 2.15 2.2 2.25 0 5 10 15 20 25 30 35 40 45 50 position of ring, r [mm] m a x . d e fl e c ti o n [ m m ] fig.(11) effect of radial position of the ring on the maximum von-mises stress. fig.(12) effect of radial position of the ring on the maximum deflection. dr. somer m. nacy /al-khwarizmi engineering journal, vol.2, no. 1,pp 15-34 (2006) 25 0.85 0.9 0.95 1 1.05 1.1 0 5 10 15 20 25 30 35 40 45 50 position of ring, r [mm] n o n -d im e n si o n a l unity p re s s u re [ p a ] fig.(13) non-dimensional representation of stresses and deflections. time [sec.] fig.(14) continuous sine-function used for all models (f = 40 hz., pmax = 250 pa). dr. somer m. nacy /al-khwarizmi engineering journal, vol.2, no. 1,pp 15-34 (2006) 26 45 49 53 57 61 65 0 5 10 15 20 25 30 35 40 45 50 position of ring, r [mm] m a x .v o n -m is e s tr e ss [ m p a ] p re s s u re [ p a ] time [sec.] fig.(15) sin-pulse function used for flat diaphragm (f = 72.3 hz., pmax = 250 pa). fig.(16) effect of radial position of the ring on the maximum von-mises stress (continuous loading). dr. somer m. nacy /al-khwarizmi engineering journal, vol.2, no. 1,pp 15-34 (2006) 27 1.5 2 2.5 3 3.5 4 0 5 10 15 20 25 30 35 40 45 50 position of ring, r [mm] m a x . d e fl e c ti o n [ m m ] flat stiffened (one and two surfases) 45 50 55 60 65 70 75 80 0 5 10 15 20 25 30 35 40 45 50 position of ring, r [mm] m a x .v o n -m is e s tr e ss [ m p a ] fig.(17) effect of radial position of the ring on the maximum deflection (continuous loading). fig.(18) effect of radial position of the ring on the maximum von-mises stress (sine-pulse loading). dr. somer m. nacy /al-khwarizmi engineering journal, vol.2, no. 1,pp 15-34 (2006) 28 2.5 2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 0 5 10 15 20 25 30 35 40 45 50 position of ring, r [mm] m a x . d e fl e c ti o n [ m m ] 0.85 0.9 0.95 1 1.05 1.1 1.15 1.2 0 5 10 15 20 25 30 35 40 45 50 position of ring [mm] n o n -d im e n si o n a l unity fig.(19) effect of radial position of the ring on the maximum deflection (sine-pulse loading). fig.(20) non-dimensional representation of stresses and deflections (continuous loading). dr. somer m. nacy /al-khwarizmi engineering journal, vol.2, no. 1,pp 15-34 (2006) 29 0.8 0.85 0.9 0.95 1 1.05 1.1 1.15 1.2 1.25 1.3 0 5 10 15 20 25 30 35 40 45 50 position of ring [mm] n o n -d im e n si o n a l unity fig.(21) non-dimensional representation of stresses and deflections (sine-pulse loading). table (1) stiffened diaphragm (two rings). cases max. von-mises stress [mpa] max. deflection [mm.] percentage reduction in max. von-mises stress flat 38.9 2.206 ---- case (1) 17.183 0.734 55.83 % case (2) 12.83 0.442 67.02 % case (3) 12.65 0.401 67.5 % dr. somer m. nacy /al-khwarizmi engineering journal, vol.2, no. 1,pp 15-34 (2006) 30 table (2) comparison between present work and the published [1]. cases max. von-mises stress [kpa] max. deflection [mm.] percentage reduction in max. von-mises stress flat 669.6 12.186 ---- ref.[1] 604.5 8.5 9.72 % case (1) 595.7 9.977 11.04 % case (2) 566 11.417 15.47 % case (3) 542.3 10.619 19 % case (4) 623.2 10.823 6.93 % case (5) 538.87 9.274 19.52 % case (6) 606.28 10.28 9.46 % case (7) 605.14 9.773 9.63 % case (8) 551.77 8.882 17.6 % case (9) 538.48 8.51 19.6 % case (10) 534.4 8.06 20.2 % case (11) 462.2 8.4 31 % dr. somer m. nacy /al-khwarizmi engineering journal, vol.2, no. 1,pp 15-34 (2006) 31 nomenclature symbol description unit br redial width of the ring m. e modulus of elasticity n/m2(pa) f frequency hz. g modulus of rigidity n/m2(pa) h diaphragm thickness m. h ring thickness m. p pressure n/m2(pa) py yield pressure n/m2(pa) r redial position of the stiffener m. r diaphragm radius m. t time sec. ν poisson’s ratio -- ρ mass density kg/m3 σy yield stress n/m2(pa) ω circular frequency rad./sec. dr. somer m. nacy /al-khwarizmi engineering journal, vol.2, no. 1,pp 15-34 (2006) 32 7.references [1] zlatan kulenović, analytical and experimental analysis of stresses and deflections of strengthened diaphragm, international design conference – design 2000, dubrovnik, may 23 – 26, 2000. [online] available http://www.io.tudelft.nl/research/ica/ind ex_publication.html [2] procedures for diaphragms. [online] available http://www.oshpd.cahwnet.gov/fdd/abo ut_us [3] r. steinmann, h. friemann, c. prescher, and r. schellin, sensors and actuators a, 48, pp. 3746,1995. [online] available http://www.el.utwente.nl/tt/publications [4] d. maier-schneider, j. maibach, and e. obermeier, journal of microelectromechanical systems, 4(4), pp. 238-241,1995. [online] available http://touch.caltech.edu/publications/sh uyun/mems95 [5] e.h. yang, s.w. han and s.s. yang, fabrication and testing of a pair of passive bivalvular microvalves composed of p + silicon diaphragms, sensors and actuators a 57, pp.(75-78), 1996. [online] available http://www.elsevier.nl/locate/sna [6] rahul saini, sunil bhardwaj, toshikazu nishida and mark sheplak, scaling relations for piezoresistive microphones, proceedings of imece, international mechanical engineering congress and exposition, november 5-10, 2000, orlando, florida. [online] available http://www.me.bringhamton.edu/miles [7] w.p. eaton, fernando bitsie, j.h. smith, and david w. plummer, a new analytical solution for diaphragm deflection and its application to a surfacemicromachined pressure sensor, technical proceedings of the international conference on molding and simulation of microsystems,1999. [online] available http://www.comppub.com/publication/m sm/99/pdf [8] klaus-jürgen bathe, finite element procedures, prentice-hall international, inc., 1996. [9] tirupathi r. chandrupatla and ashok d. belegundu, introduction to finite elements in engineering, prentice-hall of india, private limited, new delhi, 1996. [10] copper. [online] available http://www.hyperphysics.phyastr.gsu.edu [11] mechanical properties of materials, spring 2002. [online] available http://web.mit.edu/3.22/www/ps8.pdf [12] joseph edward shigley, mechanical engineering design, first metric edition, mcgraw-hill book company, 1986. http://www.io.tudelft.nl/research/ica/index_publication.html http://www.io.tudelft.nl/research/ica/index_publication.html http://www.oshpd.cahwnet.gov/fdd/about_us http://www.oshpd.cahwnet.gov/fdd/about_us http://www.el.utwente.nl/tt/publications http://touch.caltech.edu/publications/shuyun/mems95 http://touch.caltech.edu/publications/shuyun/mems95 http://www.me.bringhamton.edu/miles http://www.comppub.com/publication/msm/99/pdf http://www.comppub.com/publication/msm/99/pdf http://www.hyperphysics.phy-astr.gsu.edu/ http://www.hyperphysics.phy-astr.gsu.edu/ http://web.mit.edu/3.22/www/ps8.pdf dr. somer m. nacy /al-khwarizmi engineering journal, vol.2, no. 1,pp 15-34 (2006) 33 [13] e.j. hearn, mechanics of materials, second edition, pergman press ltd., 1985. [14] s.p. timoshinko and k.s. woinowsky, theory of plates and shells, second edition, tokyo, mcgraw-hill kogakusha ltd, 1959. [15] mohammed m. hasan, theoretical and experimental investigation of stresses and deflections of stiffened diaphragm subjected to dynamic pressure, m.sc. thesis, university of alanbar, college of engineering, department of mechanical engineering, 2002. dr. somer m. nacy /al-khwarizmi engineering journal, vol.2, no. 1,pp 15-34 (2006) 34 محمد م.حسن د.حكمت الراوي د.سومر متي ناسي قسم هندسة عمليات التصنيع كلية هندسة الخوارزمي جامعة االنبار جامعة االنبار جامعة بغداد :الخالصة ركزيتين تناول هذا البحث دراسة االجهادات و االنحرافات في األغشية الدائرية والمقواة بحلقة أو حلقتين م محددة من ديناميكي منتظم . تمت عملية النمذجة باستخدام طريقة العناصر ال تحت تأثير ضغط استاتيكي أو . nastranخالل برامجية تأثير تثبيت إلجراء دراسة تصميمية جديدة تم األخذ بنظر االعتبار تأثير حلقة التقوية المثبتة في الجوانب و ( .1در )لدراسة تمت المقارنة مع نتائج المصحلقات التقوية على سطحي الغشاء . لبيان فعالية نتائج هذه ا من نتائج هذه الدراسة يمكن استخالص صالحية التصميم االمثل لألغشية المقواة . حسن اياد وعلي حسين al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 8, no. 3, pp 24 39 (2012) empirical equations for analysis of two-way reinforced concrete slabs hassan ayad fadhil ali hussein ali al-ahmed* department of civil engineering/ college of engineering/ university of baghdad *email: ali_hussein_alahmed@yahoo.co.uk (received 9 june 2011; accepted 7 august 2012) abstract there are many different methods for analysis of two-way reinforced concrete slabs. the most efficient methods depend on using certain factors given in different codes of reinforced concrete design. the other ways of analysis of two-way slabs are the direct design method and the equivalent frame method. but these methods usually need a long time for analysis of the slabs. in this paper, a new simple method has been developed to analyze the two-way slabs by using simple empirical formulae, and the results of final analysis of some examples have been compared with other different methods given in different codes of practice. the comparison proof that this simple proposed method gives good results and it can be used in analysis of two-way slabs instead of other methods. keywords: analysis, two-way, reinforced concrete slabs, empirical equations, inflection lines. 1. introduction there are many methods to estimate the values of the bending moments occur in reinforced concrete slabs, and perhaps the most common methods which depend on coefficients taken from special tables available in codes such as the method of bs code cp110 and the method of aci code 63. these methods are approximate but practical and were formed in such a way that the moments are conservative because these methods neglected many important factors to obtain positive and negative bending moments by simple and fast way without complexity. the high accuracy in design calculations of structures is undesirable because there is no capability of estimating many factors affecting on design results such as live loads, material properties and methods of analysis and many other factors. 2. analysis of two way slab system the coefficients used in different codes depend on the aspect ratio of reinforced concrete slabs, the boundary conditions at their edges (method of restrained) and the continuity or discontinuity of the edges. and to find negative and positive bending moments, these coefficients are multiplied by the load per unit area by the square of the span. so it is important for the designer to use tables to find these coefficients. the most common manual calculation methods for calculating bending moments in reinforced concrete slabs are: 1. method two in aci 63 code (1): this method is the most common method used in design because of the simplicity in spite of that this method gives high conservative results which leads to increase in the quantity of steel reinforcement. 2. method three in aci 63 code (1): this method is recommended to use by the latest aci codes because it is more accurate than method two but it is more complicated. 3. method one in aci 63 code (1): this method is seldom used in spite of it is more accurate than the above mentioned two methods because it needs more effort calculations. mailto:ali_hussein_alahmed@yahoo.co.uk hassan ayad fadhil al-khwarizmi engineering journal, vol. 8, no.3, pp 2439 (2012) 25 4. method of bs cp110 (3 and 6). 5. aci direct design method (2, 4 and 5): this method is limited so it cannot be used in many cases. 6. equivalent frame method: this method in spite of it is accuracy and adequacy but it needs much effort and time for calculations. 3. description of the proposed method the proposed method in this paper depends on evaluating the coefficient (c) from simple empirical equation. the numbers 0.26 & 0.67 mentioned below were predicted from curve fitting to suit the other methods given by the acicode and cp110. this equation is expressed as: 26.0 l l 67.0c 1 −= … (1) where: l: is the distance between inflection lines in direction of bending moment required. l1: is the distance between inflection lines in direction opposite to the direction of bending moment required. to obtain positive and negative bending moments, the equation given below has been developed 2swbcm ×××= (as method 1 acicode 63) … (2) where: b: is a coefficient extracted from aci code (1) or bs cp110 (3 and 6) which is dedicated to find flexural bending in beams or one-way slabs as shown in fig. (1). w: is the total applied load (dead plus live) per unit area. s: is the clear span in the direction of the required bending moment. the identification of inflection lines between the positive and negative bending moments usually depends on approximate methods. it was found that the location of these inflection lines depends mainly on dimensions of spans of the neighboring panels. also, in case of continuous panels from both sides, the ratio of l l or ( 1 1 l l ) is 0.76. while, in the case of panel continuous from one side and discontinuous from opposite side, the ratio of l l or ( 1 1 l l ) is 0.87. where: l: is the clear span in direction of required bending moment (same as s). l1: is the clear span in direction opposite to the required bending moment it is worth to mention that these values are accurate and acceptable if the ratio of the spans of the neighboring panels ranging between (2/3 3/2). otherwise (when the ratio is beyond this range) the identification of the inflection lines may be evaluated according to the theory of structures. fig. (2) shows the inflection lines in panels according to aci 63 code (1). note: the values shown in fig.(1) are not be applicable if the larger of two adjacent spans is greater than the shorter by 20%. 4. comparison of results with other methods a comparison study was done to check the adequacy of the proposed method as it compared with the results obtained using the aci code (1) and the bs standard methods (3). tables (1, 2, 3 and 4) illustrate flexural positive and negative bending moments as functions to the applied load (w) for the proposed panels shown in fig. (3, 4, 5 and 6) respectively. in these tables the symbols (m+)x, (m+)y, (m-)x and (m-)y are defined as below: (m+)x = maximum positive bending moment in short direction. (m-)x = maximum negative bending moment in short direction at continuous edges. (m+)y = maximum positive bending moment in long direction. (m-)y = maximum negative bending moment in long direction at continuous edges. hassan ayad fadhil al-khwarizmi engineering journal, vol. 8, no.3, pp 2439 (2012) 26 1 14 1 9 1 9 1 14 1 14 1 10 1 11 1 16 1 11 1 11 (a) two continuous spans. (b) more than two continuous spans. fig. 1. values of the coefficient (b) used in equation (2). beams beam l (d) panel continuous at three edges. l=0.87l 1l=0.76l1 l1 inflection lines (e) panel continuous at all edges. l1 1l=0.76l1 l l=0.76l inflection lines fig. 2. inflection lines in reinforced concrete panels according to aci 63 code. l1=l1 l=l (a) panel discontinuous at all edges. l1=l1 l l=0.87l inflection line (b) panel continuous at one edge. l (c) panel continuous at two edges. l1 l1=0.87l1 l=0.87l inflection lines l1=l1 l=l (a) panel discontinuous at all edges. hassan ayad fadhil al-khwarizmi engineering journal, vol. 8, no.3, pp 2439 (2012) 27 fig. 3. proposed panels of m=0.6 used for the comparison between the proposed method and other methods. table 1, comparison among different methods. panel moment bs method method (ii) aci 63 code method (iii), aci 63 code average of methods standard deviation proposed method dead loads live loads average i (m+)x 0.786 0.765 0.687 0.868 0.778 0.776 0.00865 0.793 (m-)x 1.050 1.011 1.153 1.153 1.153 1.071 0.05990 1.110 (m+)y 0.454 0.480 0.252 0.324 0.288 0.407 0.08505 0.365 (m-)y 0.609 0.635 0.396 0.396 0.396 0.547 0.10706 0.511 ii (m+)x 0.605 0.674 0.467 0.765 0.616 0.632 0.03027 0.825 (m-)x 0.799 0.894 1.102 1.102 1.102 0.932 0.12653 1.200 (m+)y 0.363 0.402 0.144 0.252 0.198 0.321 0.08842 0.234 (m-)y 0.480 0.531 0.216 0.216 0.216 0.409 0.13805 0.328 iii (m+)x 0.566 0.609 0.441 0.752 0.597 0.591 0.01812 0.694 (m-)x 0.747 0.816 1.050 1.050 1.050 0.871 0.12967 1.009 (m+)y 0.311 0.324 0.144 0.252 0.198 0.278 0.05658 0.320 (m-)y 0.415 0.428 0.360 0.360 0.360 0.401 0.02947 0.465 iv (m+)x 0.730 0.674 0.622 0.842 0.732 0.712 0.02688 0.662 (m-)x 0.955 0.894 1.037 1.037 1.037 0.962 0.05859 0.927 (m+)y 0.363 0.402 0.252 0.324 0.288 0.351 0.04731 0.450 (m-)y 0.480 0.531 0.648 0.648 0.648 0.553 0.07033 0.655 v (m+)x 1.080 0.881 0.946 0.998 0.972 0.978 0.08134 1.153 (m-)x (m+)y 0.557 0.570 0.432 0.396 0.414 0.514 0.07068 0.520 (m-)y 0.739 0.752 0.864 0.864 0.864 0.785 0.05611 0.727 vi (m+)x 0.873 0.881 0.726 0.881 0.804 0.853 0.03457 0.947 (m-)x 1.149 1.166 1.231 1.231 1.231 1.182 0.03534 1.326 (m+)y 0.557 0.570 0.216 0.288 0.252 0.460 0.14694 0.404 (m-)y x y 6 m 3.6 m m = spanlong spanshort =0.6 6 m 6 m 6 m 3.6 m 3.6 m 3.6 m panel i panel v panel ii panel iv panel iii panel vi hassan ayad fadhil al-khwarizmi engineering journal, vol. 8, no.3, pp 2439 (2012) 28 table 2, comparison among different methods. panel moment bs method method (ii) aci 63 code method (iii), aci 63 code average of methods standard deviation proposed method dead loads live loads average i (m+)x 0.896 0.891 0.779 0.965 0.872 0.886 0.01034 0.851 (m-)x 1.200 1.173 1.339 1.339 1.339 1.237 0.07273 1.192 (m+)y 0.560 0.592 0.348 0.432 0.390 0.514 0.08865 0.480 (m-)y 0.752 0.784 0.588 0.588 0.588 0.708 0.08585 0.672 ii (m+)x 0.704 0.779 0.539 0.843 0.691 0.725 0.03878 0.890 (m-)x 0.912 1.029 1.317 1.317 1.317 1.086 0.17018 1.295 (m+)y 0.448 0.496 0.192 0.348 0.270 0.405 0.09722 0.335 (m-)y 0.592 0.656 0.324 0.324 0.324 0.524 0.14382 0.469 iii (m+)x 0.656 0.688 0.501 0.827 0.664 0.669 0.01360 0.745 (m-)x 0.848 0.923 1.216 1.216 1.216 0.996 0.15878 1.084 (m+)y 0.384 0.400 0.228 0.384 0.306 0.363 0.04106 0.420 (m-)y 0.512 0.528 0.540 0.540 0.540 0.527 0.01147 0.611 iv (m+)x 0.816 0.779 0.683 0.917 0.800 0.798 0.01515 0.706 (m-)x 1.072 1.029 1.152 1.152 1.152 1.084 0.05097 0.989 (m+)y 0.448 0.496 0.348 0.432 0.390 0.445 0.04334 0.565 (m-)y 0.592 0.656 0.924 0.924 0.924 0.724 0.14382 0.822 v (m+)x 1.216 1.024 1.003 1.083 1.043 1.094 0.08638 1.229 (m-)x (m+)y 0.688 0.704 0.540 0.540 0.54 0.644 0.07383 0.652 (m-)y 0.912 0.928 1.200 1.200 1.200 1.013 0.13216 0.912 vi (m+)x 1.024 1.024 0.848 1.003 0.926 0.991 0.04620 1.023 (m-)x 1.344 1.355 1.477 1.477 1.477 1.392 0.06027 1.432 (m+)y 0.688 0.704 0.276 0.396 0.336 0.576 0.16983 0.579 (m-)y fig. 4. proposed panels of m=0.667 used for the comparison between the proposed method and other methods. m = spanlong spanshort =0.667 x y 6 m 6 m 6 m 6 m 4.0 m 4.0 m 4.0 m 4.0 m panel i panel v panel ii panel iv panel iii panel vi hassan ayad fadhil al-khwarizmi engineering journal, vol. 8, no.3, pp 2439 (2012) 29 table 3, comparison among different methods. panel moment bs method method (ii) aci 63 code method (iii), aci 63 code average of methods standard deviation proposed method dead loads live loads average i (m+)x 0.998 1.007 0.852 1.039 0.946 0.984 0.02689 0.904 (m-)x 1.332 1.330 1.504 1.504 1.504 1.389 0.08156 1.265 (m+)y 0.678 0.716 0.444 0.552 0.498 0.631 0.09508 0.595 (m-)y 0.910 0.949 0.804 0.804 0.804 0.888 0.06127 0.833 ii (m+)x 0.780 0.871 0.613 0.916 0.765 0.805 0.04684 0.951 (m-)x 1.037 1.155 1.529 1.529 1.529 1.240 0.20973 1.383 (m+)y 0.542 0.600 0.240 0.444 0.342 0.495 0.11052 0.435 (m-)y 0.716 0.794 0.468 0.468 0.468 0.659 0.13899 0.609 iii (m+)x 0.734 0.761 0.555 0.897 0.726 0.740 0.01497 0.791 (m-)x 0.959 1.020 1.368 1.368 1.368 1.116 0.18016 1.150 (m+)y 0.465 0.484 0.300 0.480 0.390 0.446 0.04058 0.521 (m-)y 0.620 0.639 0.732 0.732 0.732 0.664 0.04894 0.757 iv (m+)x 0.889 0.871 0.723 0.981 0.852 0.871 0.01511 0.744 (m-)x 1.177 1.155 1.226 1.226 1.226 1.186 0.02968 1.042 (m+)y 0.542 0.600 0.444 0.552 0.498 0.547 0.04177 0.681 (m-)y 0.716 0.794 1.212 1.212 1.212 0.907 0.21777 0.990 v (m+)x 1.332 1.162 1.033 1.129 1.081 1.192 0.10460 1.294 (m-)x (m+)y 0.832 0.852 0.684 0.684 0.684 0.789 0.07493 0.784 (m-)y 1.104 1.123 1.512 1.512 1.512 1.246 0.18802 1.097 vi (m+)x 1.140 1.162 0.949 1.097 1.023 1.108 0.06101 1.093 (m-)x 1.521 1.536 1.723 1.723 1.723 1.593 0.09189 1.530 (m+)y 0.832 0.852 0.396 0.540 0.468 0.717 0.17649 0.754 (m-)y fig. 5. proposed panels of m=0.733 used for the comparison between the proposed method and other methods. m = spanlong spanshort =0.733 x y 6 m 6 m 6 m 6 m 4.4 m 4.4 m 4.4 m 4.4 m panel i panel v panel ii panel iv panel iii panel vi hassan ayad fadhil al-khwarizmi engineering journal, vol. 8, no.3, pp 2439 (2012) 30 table 4, comparison among different methods. panel moment bs method method (ii) aci 63 code method (iii), aci 63 code average of methods standard deviation proposed method dead loads live loads average i (m+)x 1.083 1.106 0.899 1.106 1.003 1.064 0.04414 0.950 (m-)x 1.440 1.475 1.636 1.636 1.636 1.517 0.08535 1.331 (m+)y 0.806 0.852 0.576 0.720 0.648 0.769 0.08737 0.710 (m-)y 1.083 1.129 1.044 1.044 1.044 1.085 0.03474 0.994 ii (m+)x 0.864 0.945 0.668 0.968 0.818 0.876 0.05250 1.006 (m-)x 1.140 1.267 1.728 1.728 1.728 1.378 0.25263 1.463 (m+)y 0.645 0.714 0.360 0.612 0.486 0.615 0.09547 0.535 (m-)y 0.852 0.945 0.612 0.612 0.612 0.803 0.14029 0.750 iii (m+)x 0.783 0.829 0.599 0.945 0.772 0.795 0.02469 0.832 (m-)x 1.037 1.106 1.498 1.498 1.498 1.214 0.20302 1.210 (m+)y 0.553 0.576 0.396 0.612 0.504 0.544 0.03003 0.621 (m-)y 0.737 0.760 0.972 0.972 0.972 0.823 0.10578 0.903 iv (m+)x 0.956 0.945 0.737 1.014 0.876 0.926 0.03541 0.776 (m-)x 1.256 1.267 1.267 1.267 1.267 1.263 0.00519 1.087 (m+)y 0.645 0.714 0.540 0.684 0.612 0.657 0.04250 0.796 (m-)y 0.852 0.945 1.476 1.476 1.476 1.091 0.27487 1.157 v (m+)x 1.428 1.290 1.037 1.175 1.106 1.275 0.13190 1.350 (m-)x (m+)y 0.991 1.014 0.792 0.828 0.810 0.938 0.09123 0.916 (m-)y 1.313 1.336 1.836 1.836 1.836 1.495 0.24131 1.282 vi (m+)x 1.267 1.290 1.037 1.175 1.106 1.221 0.08186 1.156 (m-)x 1.693 1.705 1.981 1.981 1.981 1.793 0.13303 1.619 (m+)y 0.991 1.014 0.540 0.684 0.612 0.872 0.18432 0.928 (m-)y fig. 6. proposed panels of m=0.8 used for the comparison between the proposed method and other methods. m = spanlong spanshort =0.8 x y 6 m 6 m 6 m 6 m 4.8 m 4.8 m 4.8 m 4.8 m panel i panel v panel ii panel iv panel iii panel vi hassan ayad fadhil al-khwarizmi engineering journal, vol. 8, no.3, pp 2439 (2012) 31 figures (7, 8, 9, 10, 11 and 12) show the relation between the aspect ratio (m) and the bending moments as a function to (w) for panels (i, ii, iii, iv, v and vi) respectively. fig. 7. relationships between (m = short span/long span) and bending moments as functions to w for panel i. 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 0.6 0.7 0.8 m (m x ) a s a re la tio n to w bs method ii aci-63 method iii aci-63 proposed method 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 0.6 0.7 0.8 m (m x + ) a s a re la tio n to w bs method ii aci-63 method iii aci-63 proposed method 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 0.6 0.7 0.8 m (m y + ) a s a re la tio n to w bs method ii aci-63 method iii aci-63 proposed method 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 0.6 0.7 0.8 m (m y ) a s a re la tio n to w bs method ii aci-63 method iii aci-63 proposed method continuous edges discontinuous edge mx mx + my + my x y hassan ayad fadhil al-khwarizmi engineering journal, vol. 8, no.3, pp 2439 (2012) 32 fig. 8. relationships between (m = short span/long span) and bending moments as functions to w for panel ii. 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 0.6 0.7 0.8 m (m y ) a s a re la tio n to w bs method ii aci-63 method iii aci-63 proposed method 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 0.6 0.7 0.8 m (m x + ) a s a re la tio n to w bs method ii aci-63 method iii aci-63 proposed method 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 0.6 0.7 0.8 m (m x ) a s a re la tio n to w bs method ii aci-63 method iii aci-63 proposed method 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 0.6 0.7 0.8 m (m y + ) a s a re la tio n to w bs method ii aci-63 method iii aci-63 proposed method continuous edges discontinuous edge mx mx + my + my continuous edge mx x y hassan ayad fadhil al-khwarizmi engineering journal, vol. 8, no.3, pp 2439 (2012) 33 fig. 9. relationships between (m = short span/long span) and bending moments as functions to w for panel iii. 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 0.6 0.7 0.8 m (m x + ) a s a re la tio n to w bs method ii aci-63 method iii aci-63 proposed method 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 0.6 0.7 0.8 m (m x ) a s a re la tio n to w bs method ii aci-63 method iii aci-63 proposed method 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 0.6 0.7 0.8 m (m y + ) a s a re la tio n to w bs method ii aci-63 method iii aci-63 proposed method 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 0.6 0.7 0.8 m (m y ) a s a re la tio n to w bs method ii aci-63 method iii aci-63 proposed method continuous edges mx mx + my + my continuous edges mx my x y hassan ayad fadhil al-khwarizmi engineering journal, vol. 8, no.3, pp 2439 (2012) 34 fig. 10. relationships between (m = short span/long span) and bending moments as functions to w for panel iv. 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 0.6 0.7 0.8 m (m x + ) a s a re la tio n to w bs method ii aci-63 method iii aci-63 proposed method 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 0.6 0.7 0.8 m (m x ) a s a re la tio n to w bs method ii aci-63 method iii aci-63 proposed method mx + my x 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 0.6 0.7 0.8 m (m y + ) a s a re la tio n to w bs method ii aci-63 method iii aci-63 proposed method 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 0.6 0.7 0.8 m (m y ) a s a re la tio n to w bs method ii aci-63 method iii aci-63 proposed method continuous edges mx my + my discontinuous edge y hassan ayad fadhil al-khwarizmi engineering journal, vol. 8, no.3, pp 2439 (2012) 35 fig. 11. relationships between (m = short span/long span) and bending moments as functions to w for panel v. my + x continuous edge my discontinuous edges 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 0.6 0.7 0.8 m (m x + ) a s a re la tio n to w bs method ii aci-63 method iii aci-63 proposed method 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 0.6 0.7 0.8 m (m x ) a s a re la tio n to w bs method ii aci-63 method iii aci-63 proposed method 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 0.6 0.7 0.8 m (m y + ) a s a re la tio n to w bs method ii aci-63 method iii aci-63 proposed method 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 0.6 0.7 0.8 m (m y ) a s a re la tio n to w bs method ii aci-63 method iii aci-63 proposed method y mx + hassan ayad fadhil al-khwarizmi engineering journal, vol. 8, no.3, pp 2439 (2012) 36 fig. 12. relationships between (m = short span/long span) and bending moments as functions to w for panel vi. 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 0.6 0.7 0.8 m (m x + ) a s a re la tio n to w bs method ii aci-63 method iii aci-63 proposed method 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 0.6 0.7 0.8 m (m x ) a s a re la tio n to w bs method ii aci-63 method iii aci-63 proposed method 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 0.6 0.7 0.8 m (m y + ) a s a re la tio n to w bs method ii aci-63 method iii aci-63 proposed method 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 0.6 0.7 0.8 m (m y ) a s a re la tio n to w bs method ii aci-63 method iii aci-63 proposed method continuous edge mx mx + my + discontinuous edges x y hassan ayad fadhil al-khwarizmi engineering journal, vol. 8, no.3, pp 2439 (2012) 37 example: find the positive and negative flexural moments for panels i and ii shown in fig. (13): solution panel i flexural moments in short direction 472.026.0 87.04 76.0567.0c =− × × ×= w539.0w4 14 1472.0m 2 =×××=+ w755.0w4 10 1472.0m 2 =×××=− flexural moments in long direction 354.026.0 76.05 87.0467.0c =− × × ×= w552.0w5 16 1354.0m 2 =×××=+ w804.0w5 11 1354.0m 2 =×××=− 4 m 3 m 5 m panel i panel ii fig. 13. panel ii flexural moments in short direction 857.026.0 76.03 76.0567.0c =− × × ×= w482.0w3 16 1857.0m 2 =×××=+ w701.0w3 11 1857.0m 2 =×××=− flexural moments in long direction 142.026.0 76.05 76.0367.0c =− × × ×= w222.0w5 16 1142.0m 2 =×××=+ w323.0w5 11 1142.0m 2 =×××=− hassan ayad fadhil al-khwarizmi engineering journal, vol. 8, no.3, pp 2439 (2012) 38 5. discussion 1. in case of panel i (corner panel), the proposed method gives less value of (m+)x & (m-)x, (maximum difference is 14.10% & 18.64% respectively) as compared with other methods for large values of m. while (m+)y and (m-)y are in good agreement with the other methods. 2. in case of panel ii (discontinuous at one short edge), the proposed method gives more value of (m+)x as compared with the other methods with maximum difference of 36.36%. while (m-)x, (m+)y and (m-)y obtained by proposed method are in good agreement with the other methods. 3. in case of panel iv (discontinuous at one long edge), the proposed method gives less value of (m+)x & (m-)x (maximum difference is 18.83% & 14.21% respectively) as compared with other methods in all values of m. while (m+)y and (m-)y are in good agreement with other methods. 4. in case of panel vi (discontinuous at three edges), the proposed method gives more value of (m-)x for smaller value of m than the other methods by maximum difference of 17.79% , while it gives less value of (m-)x for larger value of m compared other methods with maximum difference of 18.27%. 6. recommendations the proposed formulae presented in this paper can be used for analyzing of reinforced concrete two-way slabs supporting on beams. these slabs are square or rectangular with aspect ratio not exceeding 2. the coefficient b used in equation 2 can be taken from the coefficient used in aci code for evaluating the values of flexural moment in beams or one-way slabs. if the difference between two adjacent spans exceeds by more than 20% from the shorter span, then the value of coefficient b can be estimated according to theory of structures as well as the inflection lines. 7. references [1] building code requirements for reinforced concrete (aci-63). detroit: american concrete institute, 1963. [2] building code requirements for reinforced concrete (aci 318-11). detroit: american concrete institute, 2011. [3] code of practice for the structural use of concrete, cp 110, part 1, nov. 1997. [4] wang c. k, salmon c. g. and pincheira j. a., "reinforced concrete design", 7th edition, john wiley and sons, iwc, 2007. [5] nilson a. h., darwin da., and dolan c. w., "design of concrete structures", 14th edition, mcgrawhill book co., 2010. [6] allen a. h., "reinforced concrete design to cp 110", cement and concrete association, london, 1974. )2012( 24 39 ، صفحة3دد، الع8 مجلة الخوارزمي الھندسیة المجلد حسن ایاد فاضل 39 معادالت وضعیة لتحلیل البالطات الخرسانیة المسلحة العاملة باتجاھین *أحمد-علي حسین علي ال فاضل حسن ایاد جامعة بغداد / كلیة الھندسة / قسم الھندسة المدنیة ali_hussein_alahmed@yahoo.co.uk :االلكتروني البرید* الخالصة ان اغلب ھذه الطرق تعتمد اما على استخدام ثوابت محددة . تتوفر عدة طرق مثبتة في المراجع والمدونات لتحلیل البالطات الخرسانیة العاملة باتجاھین او تعتم د طریق ھ . ف ي الم دونات الش ائعة االس تخدام مت وفرة وھناك جداول لھذه الثوابت. ابعاد البالطة وطریقة تثبیتھا عند الحافات ولحاالت مختلفة من نسبة .التحلیل على طریقھ التصمیم المباشر او طریقة الھیكل المكافئ و ھذه الطریقتین تحتاج على االغلب الى وقت طویل لتحلیل البالطات وللتاكد من صالحیة ھذه المعادالت تم اجراء دراسة . المعادالت للبالطات العاملة باتجاھین تم استنباط صیغ لمعادالت ریاضیة مبسطة والجل تبسیط حل جاھین وقد تم عاملة باتمقارنة للنتائج المستحصلة من ھذه المعادالت مع الطرق المعتمدة في المدونات الشائعة االستخدام والمتبعة حالیا في تحلیل البالطات ال ون الحاجھ الى الحصول على نتائج جیده من ھذه المقارنھ مما یفسح المجال لالستفادة من ھذه المعادالت في تحلیل البالطات باتجاھین بیسر وبوقت قصیر د .الرجوع الى الجداول الموجودة في المدونات mailto:ali_hussein_alahmed@yahoo.co.uk abstract al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 8, no. 1, pp 27 36 (2012) a new audio steganography system based on auto-key generator inas jawad kadhim department of electric power engineering techniques/college of electric & electronic techniques email: inascnn95@yahoo.com (received 16 january 2011; accepted 18 0ctober 2011) abstract stenography is the art of hiding the very presence of communication by embedding secret message into innocuous looking cover document, such as digital image, videos, sound files, and other computer files that contain perceptually irrelevant or redundant information as covers or carriers to hide secret messages. in this paper, a new least significant bit (lsb) nonsequential embedding technique in wave audio files is introduced. to support the immunity of proposed hiding system, and in order to recover some weak aspect inherent with the pure implementation of stego-systems, some auxiliary processes were suggested and investigated including the use of hidden text jumping process and stream ciphering algorithm. besides, the suggested system used self crypto-hiding pseudo random key generator. the auto-key generator has purposes to investigate the encryption and embedding processes .the hiding results shows no noise in the stego-wave file after embedding process, also no difference in size is found between the original wave audio file and stego-wave file. keywords: audio steganography, text hiding, (lsb) technique. 1. introduction steganography, from the greek, means covered, or secret writing, and is a long-practiced form of hiding information. although related to cryptography, they are not the same. steganography's intent is to hide the existence of the message, while cryptography scrambles a message so that it cannot be understood. steganography includes a vast array of techniques for hiding messages in a variety of media. among these methods are invisible inks, microdots, digital signatures, covert channels and spread-spectrum communications. today, thanks to modern technology, steganography is used on text, images, sound, signals, and more [1]. cryptography is the study of mathematical techniques related to aspects of information security such as confidentiality, data integrity, entity authentication, and data origin authentication [2]. this paper introduces a new steganography system based on lsb technique using non compressed wave audio file. the embedding text can be enciphered then embedded using the same bytes. of the wave file, as an encryption and hiding keys, of course the two used bytes are different from each others to increase the complexity of the hiding algorithm. the hiding results show no noise that can be heard in the stego-wave file after embedding process. the proposed steganography system was chosen because the wave files is common in used in all communication means like, internet, mobiles, computers etc. since the wave file has huge data, it is considered a good container of a big message. when random lsb technique is used, it will be hard to detect or broken. the proposed hiding algorithm can be considered a simple idea for encryption and hiding, but not the best efficient method for hiding. mailto:inascnn95@yahoo.com inas jawad kadhim al-khwarizmi engineering journal, vol. 8, no. 1, pp 27 36 (2012) 28 2. steganography the word steganography comes from the greek steganos (covered or secret) and graphy (writing or drawing) and it means literally covered writing. cover is an input to the stego-system, in which the embedded will be hidden. the possible cover carriers are innocent looking carriers (images, audio, video, text, or some other digitally representative code) which will hold the hidden information. embedded is something to be hidden in the cover. a message is the information hidden and may be plaintext, ciphertext, images, or anything that can be embedded into a bit stream. embedding is the process of hiding the embedded message. stego is the output from the stego-system and is something that has the embedded message hidden in it. together the cover carrier and the embedded message create a stego-carrier. hiding information may require a stegokey which is additional secret information, such as a password, required for embedding the information. for example, when a secret message is hidden within a cover image, the resulting product is a stego-image. extracting is getting the embedded message out of the stego message again. new terminology with respect to attacks and breaking steganography schemes is similar to cryptographic terminology; however, there are some significant differences. just as a cryptanalyst applies cryptanalysis in an attempt to decode or crack encrypted messages, the steganalyst is one who applies steganalysis in an attempt to detect the existence of hidden information. with cryptography, comparison is made between portions of the plaintext (possibly none) and portions of the ciphertext. in steganography, comparisons may be made between the covermedia, the stego-media, and possible portions of the message. the end result in cryptography is the ciphertext, while the end result in steganography is the stego-media. the message in steganography may or may not be encrypted. if it is encrypted, then if the message is extracted, the cryptanalysis technique may be applied [3], [4]. the advantage of steganography is that it can be used to secretly transmit messages without the fact of the transmission being discovered. often, using encryption might identify the sender or receiver as somebody with something to hide. for example, that picture of your cat could conceal the plans for your company's latest technical innovation [5]. 3. steganography methods the substitution technique is one of the common and important methods of hiding information. this technique replaces data in the original file with a coded representation of the original message. the colors of "pixels", tiny elements of digital images are often represented by the value of a number contained in an eight-bit byte of data. for example, three increasingly redder shades of red might be represented as follows: “00001100” or decimal 12 might represent basic red in a particular 8-bit color palette. each of the following numbers would then represent a minor increase in the redness. “00001101” or decimal 13 “00001110” or decimal 14 the likelihood of a casual observer noticing the difference in the shades in the middle of a picture is very slight. the result is that steganographers are able to use the 2 least significant bits to encode messages and while the image does degrade slightly, it is not apparent to the naked eye [6]. 4. basic model of information hiding each steganographic technique consists of an embedding algorithm and a detection function. the embedding algorithm is used to hide secret message inside a cover (or carrier) document. the embedding process is usually protected by a keyword so that the only one who possesses the secret keyword can access the hidden message. the detector function is applied to the stegodocument and results the hidden secret message. a possible formula of the process may be represented as: cover media + embedded message + stegokey = stegomedia. figure (1) shows the general acceptable model of a steganography system. for secure covert communication, it is important that by injecting a secret message into a cover document, no detectable changes are introduced. the main goal is not to raise suspicion and avoid introducing statistically detectable modifications into the stego-document. the quantity of embedded data and the degree of host signal modification vary from one application to one other [8]. inas jawad kadhim al-khwarizmi engineering journal, vol. 8, no. 1, pp 27 36 (2012) 29 m essag e 9 ( c o v er stego medium key embeddin g process embedded key extractin g process extracted key fig. 1. general steganography system (stego-system) [7]. 5. wave audio files the riff file format is a standard published as a joint design document by ibm and microsoft. the data in wave files can be of many different types [9]. wave or wav, short for waveform audio file format [10] (also, but rarely, named, audio for windows [11]) is a microsoft and ibm audio file format standard for storing an audio bitstream on pcs. it is an application of the riff bitstream format method for storing data in “chunks”, and thus is also close to the 8svx and the aiff format used on amiga and macintosh computers, respectively. it is the main format used on windows systems for raw and typically uncompressed audio. the usual bitstream encoding is the linear pulse code modulation (lpcm) format. though a wav file can hold compressed audio, the most common wav format contains uncompressed audio in the linear pulse code modulation (lpcm) format. the standard audio file format for cds is lpcmencoded, containing two channels of 44,100 samples per second, 16 bits per sample. data format codes are listed in the following [9]: 5.1. wave file format wave files have a master riff chunk which includes a wave identifier followed by subchunks. the data is stored in little-endian byte order (see table (1)). table 1, wave file format . 5.2. format chunk the format chunk specifies the format of the data. there are 3 variants of the format chunk for sampled data. these differ in the extensions to the basic formant chunk (see table (2)). table 2, format chunk. the standard format codes for waveform data are given below (see table (3)). the references above give many more format codes for compressed data, a good fraction of which are now obsolete. field length contents ckid 4 chunk id: "fmt " cksize 4 chunk size: 16 or 18 or 40 wformattag 2 format code nchannels 2 number of interleaved channels nsamplespersec 4 sampling rate (blocks per second) navgbytespersec 4 data rate nblockalign 2 data block size (bytes) wbitspersample 2 bits per sample cbsize 2 size of the extension (0 or 22) wvalidbitspersample 2 number of valid bits dwchannelmask 4 speaker position mask subformat 16 guid, including the data format code field length contents ckid 4 chunk id: "riff" cksize 4 chunk size: 4+n waveid 4 wave id: "wave" wave chunks n wave chunks containing format information and sampled data inas jawad kadhim al-khwarizmi engineering journal, vol. 8, no. 1, pp 27 36 (2012) 30 table 3, the standard format codes for waveform data. this paper we focuses on pcm data. 5.3. pulse code modulation (pcm) format the first part of the format chunk is used to describe pcm data:  for pcm data, the format chunk in the header declares the number of bits/sample in each sample (wbitspersample). the original documentation (revision 1) specified that the number of bits per sample is to be rounded up to the next multiple of 8 bits. this rounded-up value is the container size. this information is redundant in that the container size (in bytes) for each sample can also be determined from the block size divided by the number of channels (nblockalign / nchannels).  this redundancy has been appropriated to define new formats. for instance, cool edit uses a format which declares a sample size of 24 bits together with a container size of 4 bytes (32 bits) determined from the block size and number of channels. with this combination, the data is actually stored as 32-bit ieee floats.  pcm data is two's-complement except for resolutions of 1-8 bits, which are represented as offset binary. 5.4. examples consider sampled data e.g voice.wav with the following parameters,  nc = 1 channels.  the total number of blocks is ns = 110033. each block consists of nc samples.  sampling rate f = 22050 (blocks per second).  each sample is m = 2 bytes long. as shown in table (4). table 4, example of wave file (voice.wav) format. wave files often have information chunks that precede or follow the sound data (data chunk). some programs assume that for pcm data, the file header is exactly 44 bytes long and that the rest of the file contains sound data. this is not a safe assumption. figure (2) shows voice.wav file in hexadecimal and character representation. format code preprocessor symbol data 0x0001 wave_format_pcm pcm 0x0003 wave_format_ieee_f loat ieee float 0x0006 wave_format_alaw 8-bit itu-t g.711 a-law 0x0007 wave_format_ mulaw 8-bit itu-t g.711 µ-law 0xfffe wave_format_ extensible determined by sub format field length contents ckid 4 chunk id: "riff" cksize 4 chunk size: 4+24+(8+m * nc*ns +(0 or 1))=220102 waveid 4 wave id: "wave" ckid 4 chunk id: "fmt " cksize 4 chunk size = 16 wformattag 2 wave_format_ pcm = 1 nchannels 2 nc = 1 nsamplespersec 4 f = 22050 navgbytespersec 4 f * m * nc = 44100 nblockalign 2 m * nc = 2 wbitspersample 2 rounds up to 8 * m = 16 ckid 4 chunk id: "data" cksize 4 chunk size: m * nc* ns = 220066 sampled data m * nc * ns nc*ns channel-interleaved m-byte samples pad 0 or 1 padding byte if m * nc * ns is odd inas jawad kadhim al-khwarizmi engineering journal, vol. 8, no. 1, pp 27 36 (2012) 31 fig. 2. voice .wav file in hexadecimal and character representation. 6. audio stenography system using lsbtechnique the aim of this paper is to implement an algorithm for an information hiding technique using lsb in digital wave files. this section shows the hiding and extracting algorithms supported by encryption algorithm and then shows the proposed system implementation with an experimental example. the proposed systems in information hiding algorithm consist of two main algorithms. the first one interested in hiding text in wave cover file called hiding algorithm and the second one is specialized in extracting data from the stego wave file called the extracting algorithm. 6.1. hiding algorithm this algorithm consist of two stages, these stages contribute to each other to obtain a secure algorithm. the first one is the enciphering stage and the second is embedding stage. hiding algorithm is based on hoping style. the proposed algorithm details can be described in the following steps: 1. read cover-wave file. 2. enter plain-text characters. 3. skip (60) byte from beginning of the file. 4.calculate the plaintext size (n bytes≤1/(5*8)=1/40 of the size of container) (or length), n must be embedded in the container file in order to be known during the extracted process, n represented by (3) bytes (=24 bits) then embed the 1 st bit in the lsb of the hide-byte of the container, then jump (5) bytes to embed the 2 nd bit,…and so on until finish embedding all the 24 bits. 5. embedd data: this step includes two processes: a enciphering process: consider the current byte as a encryption key-byte. this byte add (xoring) to plaintext byte according to the following equation: cipher-byte = plain-byte xor key-byte. b embedding process: consider the current byte as a jump-key embed the 1st bit of cipherbyte in the next byte using lsb technique, then jump a random step according to the following equation: jump-step = ( jump-key mod mode-byte ) + shift-byte. repeating the process to embedding the 2nd bit of cipher-byte after jumping by jump-step until finishing all bits of the cipher-byte . repeating the process in (a) and (b) until finishing all plaintext . the hiding algorithm steps as shown in figure (3). inas jawad kadhim al-khwarizmi engineering journal, vol. 8, no. 1, pp 27 36 (2012) 32 fig. 4. hiding algorithm flow chart . start read cover wave file input encipher plaintext skip 60 byte embedding n = plaintext length for i = 1 to n key-byte = encrypt-byte cipher-byte = plain-byte xor key-byte jump-key = hide-byte embed-byte = current byte embed-byte [lsb] = cipher-byte[j] jump-step=(jump-key mod mod-b)+shb output stego wave file end for j = 1 to 8 fig. 3. hiding algorithm . note: the keys encryption key-byte, hide byte, mode-byte and shift-byte are secret keys that can be send by other communication means except the same cover wave file. the flowchart of the hiding algorithm is shown in figure (4). input: reading stego-wave file process: entering plain-text skip first (60) byte from wave file let n=plain-text length (3 byte = 24 bits) embedding n in(3)bytes with(5)byte jump using hide-byte for i=1 to n key-byte = encryption key byte cipher-byte = plain-byte xor key-byte jump-key = hide-byte for j=1 to 8 embed-byte = current byte embed-byte [lsb] = cipher-byte[j] jump-step=( jump-key mod mode byte)+shift-bye endfor {j} endfor {i} output: stego wave file end inas jawad kadhim al-khwarizmi engineering journal, vol. 8, no. 1, pp 27 36 (2012) 33 6.2. practical result in this subsection we will introduce a practical example of hiding algorithm. let's choose the plain text:" information hiding system for wave audio files", which is to be hide. in figure (5) the data of two files are shown. first is voice.wav represent the audio wave file before hiding, and the second is stego.wav which represent the voice.wav file after end of hiding process. fig. 5. the data of voice.wav (before embedding) and stego.wav (after embedding). the shaded and circled hexadecimals represent the change bytes after exchanging the lsb of the specified byte. 6.3. extracting algorithm this algorithm consists of two stages.the first one is the extracting stage and the second is deciphering the extracting ciphertext. extracting algorithm details can be described as follows: 1. read stego-wave file. 2. skip (60) byte from beginning of the file. 3. extracting the embedding plaintext length (n) from the lsb of specifying bytes with (5) bytes jump using encryption key-byte. 4. extracting data: this step includes two process: aextracting process: preparing the key-byte considering the current byte as a key-byte, then consider the hide-byte as a jump-key, then extracting the 1st bit of cipher-byte from the lsb of the current byte, after that, jumping in a random step according to the following equation: jump-step = ( jump-key mod mode-byte) + shift-byte. repeating the process until get all the bits of the cipher-byte . bdeciphering process: to obtain the plain-text by: plain-byte = cipher-byte xor key-byte. repeating the process in (a) and (b) until all the plain-text characters are extracted. the extracting algorithm steps can be shown in figure (6). fig. 6. the extracting algorithm. input: reading stego-wave file process: skip first (60) byte from stego wave file extracting plaintext length (n) from lsb of the specifying bytes for i=1 to n key-byte = encryption-byte jump-key = hide-byte for j=1 to 8 embed-byte = current byte cipher-byte [j] = embed byte[lsb] jump-step=(jump-key mod mod-by)+shift-byte endfor {j} plain-byte = cipher-byte xor key-byte endfor {i} output: plaintext end inas jawad kadhim al-khwarizmi engineering journal, vol. 8, no. 1, pp 27 36 (2012) 34 the flowchart of the extracting algorithm is show in figure (7). fig.7. the extracting algorithm. 7. conclusions this paper use lsb data-hiding technique, depending on auto-key generator. it obvious the lsb-technique can be used when the cover file is uncompressed file but it can be used when the cover file is lossless compressed file, as done in .png image files. any random data added to stego file (not only in lsb) means that real noise in audio file can be heard and that's affects the extraction of the information. a random key generator is used for two purposes, first to encrypt the hidden message, and second to generate random jumping in the wave file to give more robustness to the steganography system. 8. references [1] sellars, d., “an introduction to steganography”, http://www.cs.uct.ac.za/courses/cs400w/ni s/papers99/dsellars/stego.ps.gz, 1999. [2] stinson, d. r., “cryptography: theory and practice” crc press, 1995. [3] rifat z. k. “statistical approach for steganalysis”, m.sc. thesis, applied sciences / university of technology, baghdad-iraq, 2003. [4] katzenbeisser, s. and fabien a. p. petitcolas, “information hiding techniques for steganograpghy and digital watermarking”, artech house, boston, london, 2000. [5] stalling,w., “network and internetwork security”, addison wesley professional computing series. addison-wesley, 1996. [6] al-hamami. m., “information hiding attack in image”, m. sc. thesis, iraqi commission for computer & informatics, informatics institute for postgraduate studies, baghdadiraq, 2002. [7] poluami d., debnath b., and tai-hoon k., “data hidin in audio signal : a review”, international journal of database theory and application, vol.2, no.2, june, 2009. [8] johnson, n. f., “steganography”, http://www.jjtc.com/stegdoc/, george mason university, 2003. [9] kabal, p., “audio file format specifications wave or riff wave sound file”, mcgill university,http://www.mmsp.ece.mcgill.ca/ audioformats/wave/wave.html, retrieved 2010. [10] ibm corporation and microsoft corporation (august 1991), "multimedia programming interface and data start readstego wave file skip 60 byte extracting n = plain-text length for i = 1 to n key-byte = encrypt-byte plain-byte = cipher-byte xor key-byte jump-key = hide-byte embed-byte = current byte cipher-byte[j]= embed-byte [lsb] jump-step=(jump-key mod mod-by)+sh-b output plaintext end for j = 1 to 8 http://www.cs.uct.ac.za/courses/cs400w/nis/papers99/dsellars/stego.ps.gz http://www.cs.uct.ac.za/courses/cs400w/nis/papers99/dsellars/stego.ps.gz http://www-mmsp.ece.mcgill.ca/documents/audioformats/wave/wave.html http://www-mmsp.ece.mcgill.ca/documents/audioformats/wave/wave.html http://www-mmsp.ece.mcgill.ca/documents/audioformats/wave/wave.html http://www.mmsp.ece.mcgill.ca/%20audioformats/wave/wave.html http://www.mmsp.ece.mcgill.ca/%20audioformats/wave/wave.html http://www.mmsp.ece.mcgill.ca/%20audioformats/wave/wave.html http://www.tactilemedia.com/info/mci_control_info.html http://www.tactilemedia.com/info/mci_control_info.html http://www.tactilemedia.com/info/mci_control_info.html inas jawad kadhim al-khwarizmi engineering journal, vol. 8, no. 1, pp 27 36 (2012) 35 specifications 1.0", http://www.tactilemedia.com/info/mci_co ntrol_info.html, retrieved 6-12-2009. [11] microsoft help and support, “information about the multimedia file types that windows media player supports”, microsoft corporation.12may 2008, http://support.microsoft.com/kb/316992. retrieved 29 may 2009. http://www.tactilemedia.com/info/mci_control_info.html http://www.tactilemedia.com/info/mci_control_info.html http://support.microsoft.com/kb/316992 http://support.microsoft.com/kb/316992 http://support.microsoft.com/kb/316992 http://support.microsoft.com/kb/316992 http://support.microsoft.com/kb/316992.%20retrieved%2029%20may%202009 http://support.microsoft.com/kb/316992.%20retrieved%2029%20may%202009 ((2012 27 36 ، صفحة1، العذد 8هجلة الخوارزهي الهنذسية الوجلذ ايناس جواد كاظن 36 راتينظام جذيذ لألخفاء بالصوت يعتوذ على هولذ هفتاح ايناس جواد كاظن كليت التقٌياث الكهشبائيت وااللكتشوًيت/ قسن هٌذست تقٌياث القذسة الكهشبائيت inascnn95@yahoo.com : البشيذ االلكتشوًي الخالصة لن االخفاء هى في اخفاء كل هاهى ههن باستخذام االتصاالث بىاسطت اغواس الشسالت السشيت في وثيقت غطاء ػاديت، كالصىس الشقويت، الوشئيت، هلفاث ع .الصىث وغيشها هي هلفاث الحاسىب راث الوؼلىهاث الوتكشسة تستخذم كاغطيت او حىاهل الخفاء الوؼلىهاث السشيت (. wav) باالػتواد ػلى هلفاث صىتيت هي ًىع (lbs) في هزا البحث، تن اقتشاح ًظام اخفاء غيش هتسلسل باستخذام تقٌيت االغواس بالثٌائي االقل اهويت ولضيادة دسجت االهٌيت لٌظام االخفاء الوقتشح، و للقضاء ػلى ًقاط الضؼف باستخذام تلك التقٌيت، تن اقتشاح وتحقيق بؼض الؼولياث الوساػذة وهٌها استخذام هزا الوىلذ . اخفاء باستخذام هىلذ ػشىائي راتي-ػوليت القفض بالٌص الوخفي باالضافت الى استخذام خىاسصهيت التشفيش االًسيابي واقتشاح استخذام ًظام تشفيش بؼذ ػوليت (stego)اظهشث الٌتائج اًه اليوكي اى تسوغ ضىضاء في هلفاث الصىث الوخفيه . الزاتي يؼول لتحقيق غشضيي هوا ػولياث التشفيش والتضويي . هي حيث الحجن(stego)التضويي، كزلك اليىجذ اختالف بيي هلف الصىث االصلي وهلف الصىث الوخفي mailto:inascnn95@yahoo.com������ mailto:inascnn95@yahoo.com������ عباس ومنى وعبير al-khwarizmi engineering journal, vol. 10, no. 2, p.p. removal water turbidity by crumb rubber media abbas h. sulaymon* abeer i. alwared *department of energy engineering/ **,*** department of environmental engineering *email **email: ***email: (received 9 december 2013; accepted 41 abstract the removal of water turbidity by using crumb rubber filter was investigated .the present study was conducted to evaluate the effect of variation of influent water turbidity (10, 25 and 50 n rate (25, 45 and 65 l/hr) and bed depth (30 and 60 cm) on the performance of mono crumb rubber filter in response to the effluent filtered water turbidity and head loss development, and compare it with that of co results revealed that 25 l/hr flow rate and 25 ntu influent turbidity were the best operating conditions. smaller media size and higher bed depth gave the best removal efficiency while higher media size lower head loss. the optimum results show that 92.7% removal efficiency results show that at constant operating conditions, pressure filter; about 42% reduction in pressure drop than sand filter and the conventional sand filter has a little enhancement in removal efficiency than crumb rubber filter, 96.8% for sand while for crumb rubber 92.7%. keywords: turbidity; filtration; crumb rubber med 1. introduction reuse of wastewater often requires, after the conventional secondary processing, advanced/tertiary treatment so as to meet stringent water quality objectives for reuse and to protect public health. among advanced treatment processes, gravity granular-media filtration has clearly emerged as one of the most efficient and simple processes for removing suspended and colloidal materials including pathogenic microorganisms [1]. granular media filtration of wastewater is a complex process as the effectiveness of the process is dependent on many interrelated variables and thus there is no generalized approach to the design of full-scale filters khwarizmi engineering journal, vol. 10, no. 2, p.p. 2331 (2014) removal water turbidity by crumb rubber media * muna yousif abdul-ahad** abeer i. alwared*** *department of energy engineering/ college of engineering/ university of baghdad environmental engineering college of engineering/ university of baghdad email: inas_abbas@yahoo.com *email: myabdulahad@yahoo.com **email: abeerwared@yahoo.com december 2013; accepted 41 april 2014) the removal of water turbidity by using crumb rubber filter was investigated .the present study was conducted to evaluate the effect of variation of influent water turbidity (10, 25 and 50 ntu), media size (0.6and 1.14mm), filtration rate (25, 45 and 65 l/hr) and bed depth (30 and 60 cm) on the performance of mono crumb rubber filter in response to the effluent filtered water turbidity and head loss development, and compare it with that of conventional sand filter. that 25 l/hr flow rate and 25 ntu influent turbidity were the best operating conditions. smaller media size and higher bed depth gave the best removal efficiency while higher media size and small bed depth gave head loss. the optimum results show that 92.7% removal efficiency and 8.3 mm head loss. the comparison conditions, pressure drop for crumb rubber filter is lower than conventional sand about 42% reduction in pressure drop than sand filter and the conventional sand filter has a little enhancement in removal efficiency than crumb rubber filter, 96.8% for sand while for crumb rubber 92.7%. : turbidity; filtration; crumb rubber media; head loss. reuse of wastewater often requires, after the conventional secondary processing, advanced/tertiary treatment so as to meet stringent for reuse and to protect public health. among advanced treatment media filtration has clearly emerged as one of the most efficient and simple processes for removing suspended and colloidal materials including pathogenic granular media filtration of wastewater is a complex process as the effectiveness of the process is dependent on many interrelated variables and thus there is no generalized scale filters [2]. the most important design factors are the characteristics of the filter media including type of filter media, grain size and gradation, properties of wastewater solids to be filtered, and the rate of filtration. generally, pilot scale studies are usually undertaken to evaluate the performance of the filter media to be used for filtering the wastewater in question. in the absence of a pilot study, the design must be based on experience with similar filter influent wastewater at other installations scrap tires are a solid waste, which are in increasing rates every year in particular in iraq. they have been usually disposed in landfills or tire piles with serious environmental risks. this problem may assume a larger importance in areas of tropical climate with precarious sanitation conditions moreover scrap tires piles consist a serious fire hazard [3]. al-khwarizmi engineering journal removal water turbidity by crumb rubber media college of engineering/ university of baghdad college of engineering/ university of baghdad the removal of water turbidity by using crumb rubber filter was investigated .the present study was conducted to tu), media size (0.6and 1.14mm), filtration rate (25, 45 and 65 l/hr) and bed depth (30 and 60 cm) on the performance of mono crumb rubber filter in response to nventional sand filter. that 25 l/hr flow rate and 25 ntu influent turbidity were the best operating conditions. smaller and small bed depth gave 8.3 mm head loss. the comparison drop for crumb rubber filter is lower than conventional sand about 42% reduction in pressure drop than sand filter and the conventional sand filter has a little enhancement in t design factors are the characteristics of the filter media including type of filter media, grain size and gradation, properties of wastewater solids to be filtered, and the rate of filtration. generally, pilot scale studies are usually uate the performance of the filter media to be used for filtering the wastewater in question. in the absence of a pilot study, the design must be based on experience with similar filter influent wastewater at other installations. ste, which are produced in increasing rates every year in particular in iraq. usually disposed in landfills or with serious environmental risks. this importance in areas precarious sanitation conditions moreover scrap tires piles consist a mailto:inas_abbas@yahoo.com mailto:myabdulahad@yahoo.com mailto:abeerwared@yahoo.com abbas h. sulaymon al-khwarizmi engineering journal, vol. 10, no. 2, p.p. 2331(2014) 24 about 280 million scrap tires were generated in 2000 with an annual growth of about 26%, and there are about 2000 million scrap tires in stockpiles in the us [4]. it takes a considerable time for scrap tires to decompose in natural systems. with rainwater accumulating in the void space, scrap tire stockpiles are ideal breeding grounds for mosquitoes, insects and rodents. the discarded tires can cause both health and environmental problems [5]. the management and disposal of scrap tires are of great concern in the united states. an innovative crumb rubber filtration technology has been developed to treat wastewater at penn state harrisburg [6]. it was found that crumb rubber is an excellent filter media for downward granular media filters. in comparison to traditional granular media filters (e.g., sand, anthracite, etc.), because of its elasticity, the crumb rubber filter allows higher filtration rate, lower head loss, longer filtration run time, and better effluent quality. because of its high filtration rate and low density media, the crumb rubber filter is much smaller and lighter than the conventional filters. after a filtration cycle, the crumb rubber can be backwashed with upward flow of filtered water. because of low density of rubber material, the crumb rubber filter can be backwashed at a much lower backwash water flow rate than the conventional sand/anthracite filter (20m3/hm2 versus 52.5m3/hm2) [7] . the removal of turbidity, particles, phytoplankton and zooplankton in water by crumb rubber filtration; were investigated by tang, et al [8], they concluded that there was a substantial reduction achieved. of the three variables, filter depth, media size and filtration rate, media size had the most significant influence. smaller media size favored higher removal efficiency of all targeted matter. there was no apparent relationship between removal efficiency and filter depth. higher filtration rate resulted in lower removal efficiency and higher head loss. compared with conventional granular media filters, crumb rubber filters required less backwash, and developed lower head loss. a potential use of tire crumb is as a filter in pollution control applications. past studies have shown that tire crumb can be used as an effective filter medium achieving similar results compared to using a sand/anthracite filter to remove turbidity and suspended solids. it was also indicated that the head loss associated with running water through tire crumb as opposed to the standard sand/anthracite media is significantly less [9]. factorial design was used in this study. the approach reduced the experimental burden while was effective in seeking high quality results to analyze the effects of factors and interactions. the main objective of this work is to evaluate the performance and effectiveness of sand filters by utilizing crumb rubber as filter media which is a locally available solid waste material. 2. experimental work and materials sieve analysis was used to calculate the size distribution of crumb rubber and sand. sieve analysis was carried out by shaking a weighted sample of crumb rubber and sand using (endicot sieve shaker) through a set of sieves that have progressively smaller openings. after completion the shaking period (about 25 min), the mass of sample retained on each sieve is measured using sartorius precision balance. the results of sieve analysis are generally expressed in terms of the percentage of the total weight of sample that passes through different sieves. the geometric mean size, effective size, and uniformity coefficient. are tabulated in table (1), analyzed in ministry of oil, petroleum development and research center, baghdad, iraq. a pilot plant was constructed in order to study the effectiveness of crumb rubber as a filter media. as shown in fig. 1 pvc column with 5cm inner diameter and 1 meter length was used,. turbid water was prepared in a tank by adding kaolin (red kaolin from local material),) to tap water with manual mixing. after sufficient settling period of time (about 10 to 30 min. depending on the required turbidity) to allow settling of large particles, turbid water was pumped to a gravity feeding tank to be used as an influent to the filtration column. two different size of crumb rubber 0.6 and 1.14 mm was used. for each size (0.6, 1.14 mm), the filter column was loaded to a depth of 30 and 60cm respectively. before each filter run, the filter was backwashed by air scour and then water. for each filter configuration, the filter was operated at three measured influent flow rates 25, 45, and 65 m/hr respectively using a calibrated rotameter. the effluent turbidity was measured using turbidity meter (hi 98703 hanna).the head loss through the filter media was measured using the difference between the water level in the abbas h. sulaymon al-khwarizmi engineering journal, vol. 10, no. 2, p.p. 2331(2014) 25 filter column and the water level in the glass tube connected to the bottom of the filter column both reading and recorded at fixed time intervals along the experimental duration time of 120 minutes. porosity of 0.617 and 0.62 for sizes 0.6 and 1.14mm were determined by the measurement of the dry weight of the media initially loaded to the filter column and the media depth. the performance of the optimal crumb rubber filtration conditions were compared with sand (the same size, influent turbidity, influent flow rate, and bed height) by measuring the head loss and the effluent turbidity. table 1, .sieve analysis parameters and physical charactaristis for crumb rubber and sand crumb rubber sand size, mm 0.6-1 1.14-1.18 0.6-1 effective size, mm 0.6 1.14-1.18 0.61 uniformity coefficient 1.388 1.487 1.41 density g/cm3 0.114 0.114 0.255 porosity 0.617 0.62 0.506 fig. 1. experimental setup of the crumb rubber filter. 3. results and discussion 3.1. effectof size and influnt flow rate on pressure drop and turbidty four experimental sets were carried out to study the effect of granuler size, bed height,influent flow rate, and influent turbidities on pressure drop and the percent turbidity removal are shown in figs.(2-5).it can be seen from these figures that the best flow rate was 25 l/h, higher filtration rate resulted in lower turbidity removal efficiency and the best influent turbidity was 25 ntu for all media size .it is clear that lower flow rate causes higher pressure drop,while higher flow rate causes more chanelling between the crumb particles which led to a lower pressure drop. effluent sampling air rotameter air pump air filtration column rotameter backwash tank over flow rotameter pump preparation tank feeding tank i m abbas h. sulaymon al-khwarizmi engineering journal, vol. 10, no. 2, p.p. 2331(2014) 26 3.2. optimum filtration conditions for the crumb rubber the percentage turbidity removal and pressure drop values were found from figs (25) for each of the sets 1, 2, 3, and 4 individually as shown in table 2. the best turbidity removal efficiencies for the two media sizes 0.6 and 1.14 mm were 92.7% ,90.8% respectively at constant bed height of 50 mm . these results clearly indicate that the media size played an important role in turbidity removal. this observation was expected since a smaller media size corresponds to a smaller pore size, consequently more solid matter could be strained by the filter media. also it can be seen from these figures that the bed height has less effect on removal efficiency. the best pressure drop was 8.3 cm h2o for 1.14 mm media size and 30cm bed height while for 0.6 mm media size and 30 cm bed height was 29 cm. for small media size the fine grains tend to settle on the top of the filter, which will easily clog the filter bed surface, and cause a high head loss. 3.3. comparison between optimal conditions of crumb rubber filtration and sand comparing the optimum conditions of crumb rubber with sand at influent flow rate 25 l/h, influent turbidity 25ntu.the results for pressure drop and turbidity removal efficiency with time were plotted and as shown in figs 6 and 7. table 2. optimum filtration conditions. pressure drop turbidity r2 fitting equation pressure drop cm h2o r2 fitting equation removal % 0.964 y = 0.001x2 + 0.006x + 9.087 29 0.971 y=-.006x2 + 1.376x+10.25 91.2 set no.1 0.929 y = 0.001x2 + 0.030x + 11.69 35.1 0.926 y = -0.006x2 + 1.421x + 16.59 92.7 set no.2 0.945 y = 0.000x2 + 0.001x + 2.598 8.3 0.982 y = -0.005x2 + 1.357x + 7.574 90.6 set no 3 0.947 y = 0.000x2 + 0.003x + 5.201 16.7 0.979 y = -0.005x2 + 1.362x + 8.382 90.8 set no.4 abbas h. sulaymon al-khwarizmi engineering journal, vol. 10, no. 2, p.p. 2331(2014) 27 fig. 2. set no.1, turbidity removal efficiency and pressure versus time at particle size 0.6mm and bed height =30cm fig. 3. set no.2, turbidity removal efficiency and pressure drop versus time at particle size 0.6 mm and bed height 50cm ٢٩ ٨٤.٠ ٢٩ ٩١.٢ ٣٠ ٨١.٠ ٧٢ ٨٢.٩ ٧٧ ٨٩.٧ ٨٣ ٨٠.٢ ٧٨ ٨١.٧ ٧٩ ٨١.٧ ٨٤ ٧٩.٤ ٠ ١٠ ٢٠ ٣٠ ٤٠ ٥٠ ٦٠ ٧٠ ٨٠ ٩٠ ١٠٠ ١١٠ ١٢٠ δp % re m ov al δp % re m ov al δp % re m ov al δp % re m ov al δp % re m ov al δp % re m ov al δp % re m ov al δp % re m ov al δp % re m ov al turbidity ١٠ turbidity ٢٥ turbidity ٥٠ turbidity ١٠ turbidity ٢٥ turbidity ٥٠ turbidity ١٠ turbidity ٢٥ turbidity ٥٠ flow rate٢٥l/h flow rate٤٥l/h flow rate٦٥l/h set no.1 optimum turbidity removal = 91.2% pressure drop=30cm ٠min ١٠min ٢٠min ٣٠min ٤٠min ٥٠min ٦٠min ٧٠min ٨٠min ٩٠min ١٠٠min ١١٠min ١٢٠min ٣٤.٥ ٨٦.٧ ٣٥.١ ٩٢.٧ ٣١.٠ ٨٤.٢ ٨٨.٦ ٨٥.٧ ٩٤.٤ ٩١.٤ ١٠٠.٥ ٨٣.٥ ٩٤.٦ ٨٤.٧ ٩٦.٣ ٩٠.٠ ١٠٢.١ ٨٢.٩ ٠.٠ ١٠.٠ ٢٠.٠ ٣٠.٠ ٤٠.٠ ٥٠.٠ ٦٠.٠ ٧٠.٠ ٨٠.٠ ٩٠.٠ ١٠٠.٠ ١١٠.٠ ١٢٠.٠ δp % re m ov al δp % re m ov al δp % re m ov al δp % re m ov al δp % re m ov al δp % re m ov al δp % re m ov al δp % re m ov al δp % re m ov al turbidity ١٠ turbidity ٢٥ turbidity ٥٠ turbidity ١٠ turbidity ٢٥ turbidity ٥٠ turbidity ١٠ turbidity ٢٥ turbidity ٥٠ flow rate٢٥l/h flow rate٤٥l/h flow rate٦٥l/h set no.2 optimum turbidity removal=92.7% presure drop=31cm ٠min ١٠min ٢٠min ٣٠min ٤٠min ٥٠min ٦٠min ٧٠min ٨٠min ٩٠min ١٠٠min ١١٠min ١٢٠min h2o h2o abbas h. sulaymon al-khwarizmi engineering journal, vol. 10, no. 2, p.p. 2331(2014) 28 fig. 4. set no.3, turbidity removal efficiency and pressure drop versus time at particle size 1.14mm and bed height 30cm. fig. 5. set no.4, turbidity removal efficiency and pressure drop versus time at particle size 1.14 mm and bed height 50cm. ٨.٢ ٨٢.٩ ٨.٣ ٩٠.٦ ٨.٦ ٧٩.٧ ٢٨.٨ ٨١.٦ ٣١.٠ ٨٨.٨ ٣٣.٢ ٧٩.٣ ٣٩.٠ ٨٠.٣ ٣٩.٣ ٨٦.٧ ٤٢.٢ ٧٨.٩ ٠.٠ ٢٠.٠ ٤٠.٠ ٦٠.٠ ٨٠.٠ ١٠٠.٠ ١٢٠.٠ δp % re m ov al δp % re m ov al δp % re m ov al δp % re m ov al δp % re m ov al δp % re m ov al δp % re m ov al δp % re m ov al δp % re m ov al turbidity ١٠ turbidity ٢٥ turbidity ٥٠ turbidity ١٠ turbidity ٢٥ turbidity ٥٠ turbidity ١٠ turbidity ٢٥ turbidity ٥٠ flow rate٢٥l/h flow rate٤٥l/h flow rate٦٥l/h set no.3 optimum turbidity removal=90.6% pressure drop=8.3cm ٠min ١٠min ٢٠min ٣٠min ٤٠min ٥٠min ٦٠min ٧٠min ٨٠min ٩٠min ١٠٠min ١١٠min ١٢٠min 16.0 83.2 16.7 90.8 17.5 80.1 57.7 82.0 61.9 89.0 66.4 79.7 78.0 80.7 78.5 87.0 84.3 79.4 0.0 20.0 40.0 60.0 80.0 100.0 120.0 δp % re m ov al δp % re m ov al δp % re m ov al δp % re m ov al δp % re m ov al δp % re m ov al δp % re m ov al δp % re m ov al δp % re m ov al turbidity 10 turbidity 25 turbidity 50 turbidity 10 turbidity 25 turbidity 50 turbidity 10 turbidity 25 turbidity 50 flow rate25 l/h flow rate45 l/h flow rate65 l/h set no.4 optimum turbidity removal=90.8% pressure drop=17.5cm 0 min 10 min 20 min 30 min 40 min 50 min 60 min 70 min 80 min 90 min 100 min 110 min 120 min h2o h2o abbas h. sulaymon al-khwarizmi engineering journal, vol. 10, no. 2, p.p. fig. 6. comparison for pressure drop cm h and percent optimum removal turbidity= 92.7% fig. 7. comparison for %turbidity removal with time be =0.6mm). 4. conclusions 1. flow rate affects on removal efficiency and head loss, increasing flow rate cause decreasing in removal efficiency and increase in head loss .the best flow rate was 25l/h and the best influent turbidity was 25ntu sets. 2. smaller media size and higher bed depth gave the best removal efficiency while higher media size and smaller bed depth gave better head loss. 3. the optimum removal efficiency and head loss for crumb rubber filter were 92.7% and 8.3mm respectively. 4. at constant operating conditions conven sand filter has little enhancement in removal efficiency than crumb rubber. 5. the head loss developed in crumb rubber filter is less than that in sand filter, by 42% reduction in pressure drop than sand filter at the same operating conditions. 0.0 20.0 40.0 60.0 80.0 0 pr es su re d ro p , c m h 2o ٠.٠ ٢٠.٠ ٤٠.٠ ٦٠.٠ ٨٠.٠ ١٠٠.٠ ١٢٠.٠ ٠ % tu rb id ity re m ov al ef fic ie nc y khwarizmi engineering journal, vol. 10, no. 2, p.p. 29 cm h2o with time between crumb rubber and sand (particle size= 0.6mm) removal turbidity= 92.7%. comparison for %turbidity removal with time between crumb rubber and sand flow rate affects on removal efficiency and head loss, increasing flow rate cause decreasing in removal efficiency and increase flow rate was 25l/h and influent turbidity was 25ntu for all bed depth gave the best removal efficiency while higher media size and smaller bed depth gave better the optimum removal efficiency and head loss for crumb rubber filter were 92.7% and at constant operating conditions conventional sand filter has little enhancement in removal the head loss developed in crumb rubber by about 42% reduction in pressure drop than sand . 5. references [1] mujeriego, r. and asano, t of advanced treatment in wastewater reclamation and reuse. wat. sci. tech., 5): 1-9. [2] metcalf and eddy (1991) engineering: treatment, disposal, and reuse. 3rd edition. new york: [3] abas, f. o., abass, m. o., abass, r. o. and shymaa, k. g.(2011) improvement by waste tires addition. eng. and tech. journal, 26(16): 3417-3428. [4] sunthonpagasit, n., and hickman, h. l., jr (2003) manufacturing and utilizing crumb rubber from scrap tires management. 13. [5] united states environmental protection agency (usepa) (1993) scrap tire handbook. epa/905-k-001. region 5, usa. [6] graf, c., and xie, y. f. (2000) flow filtration using crumb rubber media for tertiary wastewater filtration. keystone water quality manager, 33:12 50 100 150 time, min rubber sand ٠ ٥٠ ١٠٠ ١٥٠ time, min rubber sand khwarizmi engineering journal, vol. 10, no. 2, p.p. 2331(2014) particle size= 0.6mm) tween crumb rubber and sand (particle size mujeriego, r. and asano, t (1999) the role of advanced treatment in wastewater wat. sci. tech., 40(4(1991) wastewater atment, disposal, and new york: mcgraw-hill. abass, r. o. and improvement of soil eng. and tech. hickman, h. l., jr. manufacturing and utilizing crumb r from scrap tires. msw united states environmental protection pa) (1993) scrap tire region 5, usa. (2000) gravity down on using crumb rubber media ewater filtration. keystone 12–15. abbas h. sulaymon al-khwarizmi engineering journal, vol. 10, no. 2, p.p. 2331(2014) 30 [7] hsiung, s. y. (2003) filtration using a crumb rubber medium. m.sc. thesis, environmental engineering at penn state university.pa. usa. [8] tang, z., butkus , a. m. and xie , y.f. (2006) crumb rubber filtration: a potential technology for ballast water treatment. marine environmental research 61: 410– 423. [9] xie. y. (2007) filter media: crumb rubber for wastewater filtration, filtration and separation, 44, 30-32. 2014)( 2331، صفحة 2، العدد10دجلة الخوارزمي الھندسیة المجلم عباس حمید سلیمون 31 ازالة عكورة المیاه باستعمال المطاط كوسط ترشیح ***عبیر ابراھیم موسى **منى یوسف عبد االحد *عباس حمید سلیمون لطاقة * ھندسة ا الھندسة / قسم یة جامعة بغداد/ كل یئیة ***،** ب ل ھندسة ا ال ھندسة / قسم د/ كلیة ال جامعة بغدا inas_abbas@yahoo.com : االلكتروني البرید* myabdulahad@yahoo.com كتروني ** االل لبرید :ا abeerwared@yahoo.com :االلكتروني البرید*** الخالصة لمرشح لتاثیر كماده مرشحھ احادیة الزالة عكورة الماء من خالل اختبار كفاءة ا ) المطاط(تضمن البحث دراسة امكانیة استخدام مخلفات االطارات و ارتفاع الوسط، ساعة/لتر) ٦٥، ٤٥، ٢٥( معدل الجریان، )ملم١.١٤و ٠.٦(حجم الحبیبات ، )وحدة عكورة ٥٠، ٢٥، ١٠(الماء الداخلالتغیر في عكورة .سم على مقدار العكورة الخارجة وارتفاع عمود الماء ومقارنتھا مع مرشح الرمل التقلیدي ولمدة ساعتین حیث تم سحب نموذج كل عشرة دقائق ) ٦٠، ٣٠( كانت عند حجم % ٩٢,٧كما ان افضل نسبة ازالة بلغت ،وحدة عكوره ٢٥ساعة و /لتر ٢٥تائج كانت عند معدل جریان تم التوصل الى ان افضل الن .ملم ٨,٣سم ارتفاع الوسط حیث بلغ ٣٠ملم و ١,١٤سم ارتفاع الوسط وان ارتفاع عمود المیاه كان اقل عند حجم حبیبات ٦٠ملم و ٠,٦حبیبات لي وعند مقارنة نتائج مرشح المطاط مع المرشح الرملي عند نفس الظروف كان ارتفاع عمود المیاه في مرشح المطاط اقل من المرشح الرملي بحوا % .٩٢,٧بینما مرشح المطاط % ٩٦,٨مع ان نسبة االزالة للعكورة كانت افضل في المرشح الرملي حیث بلغت % ٤٢ mailto:inas_abbas@yahoo.com mailto:myabdulahad@yahoo.com mailto:abeerwared@yahoo.com al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 3246 (2014) experimental study of mixed convection in an enclosure with a cold movable top wall and hot bottom wall nabil j. yasin* dhia al-deen h. alwan** ayad s. abdulla*** *,** department of airconditioning and referigeration engineering / engineering technical college of baghdad department of airconditioning and referigeration engineering / engineering technical college of mosul *** nabiljamil58@yahoo.com *email: dhia716@yahoo.com email:** ayad_s00@yahoo.com *email:** (received 4 november 2013; accepted 28 january 2014) abstract mixed convection heat transfer to air inside an enclosure is investigated experimentally. the bottom wall of the enclosure is maintained at higher temperature than that of the top wall which keeps in oscillation motion, whereas the left and right walls are well insulated. the differential temperature of the bottom and top walls changed several times in order to accurately characterize the temperature distribution over a considerable range of richardson number. adjustable aspect ratio box was built as a test rig to determine the effects of richardson number and aspect ratio on the flow behavior of the air inside the enclosure. the flow fields and the average nusselt number profiles were presented in this work. the results show that, at a constant value of the richardson number, average nusselt number (nuav.) increases with aspect ratio. furthermore, as richardson number decreases, the time period decreases with constant values of aspect ratio. keywords: mixed convection, experimental, aspect ratio, enclosure, oscillating motion. 1. introduction the problem of heat transfer by mixed convection has been the subject of intensive numerical, and experimental investigations in the recent years because of its significant applications in nature and in many scientific and engineering practices such as, cooling of electronic devices[1],the design stage of ceiling radiant cooling panel (crcp)system [2], manufacturing of solar collectors, flow and heat transfer in solar ponds[3]. a survey of the literature on mixed convection in enclosures shows that most of these studies were adapted the numerical methods while very few of these studies were carried out experimentally. aydin, and yang [4] investigated numerically mixed convection in cavities with a locally heated lower wall and moving sidewalls which was assumed to be moving downward across the cavity and to be kept at a constant temperature. the remaining parts of the cavity were considered to be adiabatic. mixed convection heat transfer in a two-dimensional rectangular cavity with constant heat flux from partially heated bottom wall while the isothermal sidewalls were moving in the vertical direction, was studied by guo and sharif [5]. all computations were done for a range of richardson number from(0.1 to 10).the results show an improvement of the flow and temperature field and increasing of the nusselt number values by increasing of both of the richardson number and the heat source. hakan and dagtekin[6], abdalla al-amiri, et al.[7], sharif [8], and waheed, [9]were also studied the problem for the mixed convection in enclosures under different boundary conditions numerically and they concluded a number of explanations for the change in the mailto:nabiljamil58@yahoo.com nabil j. yasin al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 3246 (2014) 33 values of the nusselt number. khanafer and amiri[10] investigated the effects of oscillatory motion of the upper wall. the results reveal that the reynolds and grashof numbers would either enhance or retard the energy transport process and drag force behavior depending on the velocity cycle.ghasemi,and aminossadat[11] present a numerical investigation of mixed convection in a square cavity which configured such that one of the vertical walls is cooled and slides either with a constant speed or with a sinusoidal oscillation. the results indicate that the direction and magnitude of the sliding wall velocity affect the heat transfer rate. an experimental study of mixed convection and flow pattern in a lid-driven arcshape cavity were carried out by chen and cheng[12]. the top flat lid maintained at temperature δtland was moving from left to right at a constant speed. the bottom arc-shape wall is heated such that its temperature is fixed at a higher temperature. the flow visualization technique using kerosene smoke is applied to observe the flow pattern. an experimental investigation for the flow field in an enclosure with a bottom wall maintained at a temperature higher than the temperature of the top wall was done in the present work. the top wall was moving horizontally in a certain sinusoidal motion while the two other walls were perfectly insulated. the air was used to be the working fluid. 2. experimental apparatus and procedure the schematic diagram of the test rig is shown in fig.(1). the main part of the experimental rig is the enclosure which shown in fig. (2).it is a rectangular box manufactured from wood. the enclosure has a width of (300) mm and a variable height of(150)mm, (300)mm, and (600) mm. to ensure that the flow is two-dimension, the depth of the enclosure is adjusted to(1000) mm[13].the bottom wall is heated by an external plate heater fixed by bolts. three holes on the bottom side used to inject smoke inside the enclosure as shown in fig.(3).the top wall is connected to an external mechanism to provide an oscillating motion. the moving apparatus was designed and fabricated to provide a horizontal variable speed motion to the top wall according to [u=umax sin (ωt)].the oscillation amplitude (umax) represent the maximum top wall moving speed as shown in fig. (4). fig. (5) shows the moving apparatus which consists of (600mm x 1000 mm) aluminum plate,(3 mm) thickness connecting to a variable speed dc-motor with an arm. a slice of rubber was inserted between the movable part (aluminum plate) and the sides of the enclosure to prevent air leakage. the left and right walls of the enclosure were perfectly insulated to ensure that no heat exchange across them. the symptomaticwalls of the enclosure provided with two glass windows to visualize the flow field inside the enclosure as shown in fig.(6).an electrical film heater was mounted on the bottom surface of the enclosure to provide a constant heat flux. many strips of chrome-nickel alloy having a width of (1) mm and of (48) ohm/m electricalre sistance used as heating element. the heating element supplied a wide range of constant heat flux values. the power required for the heating element was controlled by adjusting the electric current supplied to the element. the flow field was visualized by imaging the smoke inside the enclosure. type-k thermocouples with a digital thermometer were used to measure the temperature distribution inside the enclosure, and the differential temperature of the cold and hot sides as in fig.(7).the thermocouples were connected in parallel to a digital thermometer by leads through a selector switch. in order to obtain accurate measurements, a calibration for the thermocouples, compensating cable, selector switch, and the measuring device were done. the angular velocity of the motor is measured by using speed meter. air flow visualized using smoke method technique. the smoke is fed into the cavity through three holes placed beneath the bottom wall of the enclosure. the two glass windows and the smoke allowed the flow field in the enclosure to be visualized by using a digital camera. during each test run, the temperature of the bottom heating surface and the top moving wall is specified and the accessories is setting according to these selected specification. a digital watch was used to control the time period of oscillation. the temperatures of the hot and the cold walls were monitoring continuously (threethermocouplest1, t2, andt3for the hot wall, and one thermocouple t7 for the cold wall) as in fig (7).each (1/4) and (3/4) period, the air temperature inside the enclosure was recorded. when the recorded temperature of a previous period and that of the later period is almost equal, for the entire air in the enclosure, the experiment assumed to be reached the steady state condition. when the enclosure is considered to be at a steady state condition the smoke has been injected to the cavity through the three holes of the bottom wall and photographs of the flow field have been done by using the digital camera. at the end of the experiment, the heating element switch off, and nabil j. yasin al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 3246 (2014) 34 the rig will allowed returning to its original temperature before starting new test run.the analyses of the experimental uncertainties of the results have been given proper attention. in the present study, the uncertainty analysis was performed by the method proposed by holman 1984[14]for all experiments, and it was found that the expected experimental error was within ±4.3%for all test runs. fig. 1. schematic diagram and a photograph of the test rig. 1. dc motor 5. glass window 2. aluminum plate 5 mm thick 6. joint with screw 3. electrical heater 7. iron frame 4. wood enclosure 8. flexible arm nabil j. yasin al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 3246 (2014) 35 3 aspect ratio =0.5 2 1 4 fig. 2 . schematic diagram of the enclosure. fig. 3. the bottom wall. 1. moving wall 3. heater at the bottom 2. window 4. side wall from wood pipe of smoke heater insulation nabil j. yasin al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 3246 (2014) 36 fig. 4.the amplitude of oscillation. fig. 5.the movable top wall. fig. 6.the side wall of enclosure. fig. 7. thermocouple distribution inside the enclosure. nabil j. yasin al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 3246 (2014) 37 3. data analysis richardson number is a measurement of the relative importance variables of the buoyancydriven natural convection to the lid-driven forced convection, which is calculated from the following equation. ri= gr/re 2 = (g.β.(th-tc ).h) /(umax.) 2 …(1) where = the nusselt number is assumed to be the reference to the effect of fluid motion on heat transfer. it is of a great interest to study this effect by determining nusselt number in each stage of heat transfer process within the enclosure. generally, and according to the heat balance which occurs between the heating surface and the air inside the enclosure, one can say that conduction heat from the heating surface is equal to the convection heat to the air in the cavity …(2) where . …(3) and …(4) where is the area of the element under investigation, and, …(5) so that, . …(6) then …(7) where = k . nu[15], but nu = and his the length of the enclosure which is the distance between the hot and cold surfaces, so that equation (6) can be written as: …(8) 4. results and discussion figs.(8) and (9) are represent photographs of the flow field at (ri=10) and (ri=5) respectively. these photographs show that the whole field consists of two cells which occupy all of the enclosure space, which is attributed to the fact the fluid flow inside the enclosure is dominated by natural convection. also it can be concluded from these photographs that, decreasing richardson number (by increasing the reynolds number) at constant values of grashof number and aspect ratio (ar= 1), will lead to increase the force convection due to increase the amplitude of oscillation at the top wall (umax). it was very difficult to image the flow field at ri=1 and ri=0.1, because the process requires increasing the top wall speed, which means that the time period required to complete one cycle is very little, unfortunately the facilities and the equipment for this job were unavailable at the time of experiments. figs. (10) and (11) represent the photographs of the flow field at (ri=5), and various values of the aspect ratio (ar=0.5, and 2).it can be conclude from these figures that the time required to complete one cycle (period) will increase when the aspect ratio is increase at the same value of the richardson number, mean that the time period is increases due to the increase the amplitude of the oscillation at the top wall (umax).the temperature measurement each (1/4 and 3/4) of the time period was used to deduce experimentally the effect of richardson number, on the average nusselt number(nuav.). fig. (12) shows the relation between average nusselt number with dimensionless time for different values of richardson number (ri=5 and 10) at constant aspect ratio (ar=1) and constant grashof number. the figure shows that the average nusselt number (nuav.) is increasing with richardson numberdecrease (ri). for example; withri=5the average nusselt number (nuav.) is (2.9) at (τ=25), while with ri=10 it is (nuav.) is (2) at the same (τ=25). also it may be concluded from the figure, that the time lag to reach the periodical steady state condition of the average nusselt number (nuav.) decreases when the richardson number decrease, for example the required time to reach the steady state condition with (ri=10) is (τ =25 ), while it is (τ=20) with(ri=5). theexplanation of this result is that, when the richardson number decreases the amplitude of the oscillation at the top plate (umax) will increased, also the oscillation frequency of the average nusselt number (nuav.) will increase which causes decrease in the time lag to reach the periodical steady state condition. fig.(13) shows the relation between the average nusselt number (nuav.) with dimensionless time at various values of the of aspect ratio and constant value of richardson number (ri=5). it shows that the average nusselt number is increased with increasing of the value of aspect nabil j. yasin al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 3246 (2014) 38 ratio at the same value of the richardson number. for example at (τ =25), the average nusselt number is (nuav.=3.3) with(ar=2) while (nuav.=2.9) with(ar=1), that is, the increase of the aspect ratio must be associate within crease the oscillating velocity at the top wall which causes the force convection to increase, and will cause an improvement in the heat transfer coefficient and increase in the average nusselt number (nuav.).a comparison between the present experimental work with numerical results which carried out by the authorshas been made as follows [ 16 ]: 1. a comparison between the experimental and numerical results for flow field is shown together in fig.(14) for (ri=5) at aspect ratio (ar=2). this figure shows the effect of richardson number and aspect ratio on the flow field inside enclosure, the flow visualization photographs are given in the left column of this figure, while the numerical contour is located on right side from figure. both contours of the numerical and experimental results consist of two cells and occupy all of the enclosure space. this means that the fluid flow inside the enclosure is dominated by natural convection. it can be seen from this figure that both contours have the same trend and behavior. 2. a comparison between resulting average nusselt number for both experimental and numerical solutions is shown in fig’s.(15) and (16). fig.(15) shows that for (ri=5) and when the steady state condition is reached at (τ=22) the maximum experimental average nusselt number (nuav.) was (2.9)), while maximum numerical average nusselt number was (nuav.=3.4) at (τ=22). error ratio between experimental and numerical values of the average nusselt number in these figures is about (14.7%). moreover fig.(16) shows that at (ri=10), and (τ=22) the maximum average nusselt number in both experimental and numerical results are(nuav.=2) and (nuav.=2.3) respectively. the error ratio between the two values is about (13%). from fig’s.(15) and (16) we may conclude that the maximum error occurs with(ri=5) and minimum error occurs with (ri=10), because, when richardson number decreases the amplitude of the oscillation at the top wall (umax) will increase which causes a decrease in the time period. also it may be concluded from these figures that the time lag to reach the periodical steady state condition of the average nusselt number (nuav.) in experimental study is greater than that for the numerical solution.for example the time to reach the steady state condition in the experimental case with ri=10 is (τ =20) while in the numerical case, it is (τ=4). to explain this feature: as the average nusselt number (nuav.) depends on the temperature difference between the hot wall and the air inside the enclosure, and at the timejust starting the experiments, the temperature of the air in the enclosure is much lower than the temperature of hot wall, so the temperature difference between the hot wall and the air is high which will increase the heat transfer coefficient. after some time the temperature of the air will increase and cause decrease in the temperature difference produced a decrease in the average nusselt number continuously until reaching the steady state condition. nabil j. yasin al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 3246 (2014) 39 0dp 1/2 dp 1/4 dp 3/4dp 3/4dp dp fig. 8. experimental flow field at ri=10 and ar=1. 0dp 1/4dp 1/2 dp 3/4dp dp fig. 9. experimental flow field at ri=5 and ar=1. nabil j. yasin al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 3246 (2014) 40 fig. 10. experimental flow field at ri=5 and ar=0.5. fig. 11. experimental flow field at ri=5 and ar=2. dp 3/4 dp 1/2 dp 1/4 dp 0dp 0dp 1/4 dp 1/2 dp 3/4 dp dp fig(9):experimental flow field at ri=5 and ar=1 nabil j. yasin al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 3246 (2014) 41 fig. 12. experimental determination of the average nusselt number versus dimensionless time at aspect ratio(ar)= 1 with different values of (ri) and constant (gr). fig. 13. the experimental determination of average nusselt number versus dimensionless time at richardson number (ri=5) with different values of (ar). nabil j. yasin al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 3246 (2014) 42 fig. 14. flow field, comparisonof the experimental and numerical work at ri=5, ar=2. nabil j. yasin al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 3246 (2014) 43 [15] fig. 15. comparing the experimental and numerical work at ri=5, and ar=1. fig. 16. comparing the experimental and numerical work at ri=10, and ar=1. [15] [15] nabil j. yasin al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 3246 (2014) 44 5. conclusions 1when richardson number decreases due to the increase in the value of reynolds number at constant values of aspect ratio and grashof number, the time period is decrease. 2the time period increases when the aspect ratio increases at the constant value of the richardson number. 3average nusselt number (nuav.) increases when the aspect ratio increases at the constant value of the richardson number. 4time lag to reaches the periodical study state condition of the average nusselt number (nuav.) decrease when the richardson number increases. 5the average nusselt number increases when reynolds number increases at constant values of the aspect ratio and grashof number. nomenclatures units definition symbols -aspect ratio ar=w/h ar m 2 area of element under investigation aelem -dimensionless period (dp=2π /s) dp rad frequency f -grashof number gr=(g. β.(th-tc).h 3 )/ѵ 2 gr m/s² acceleration due to gravity g m height of the enclosure h w/m². ˚c heat transfer coefficient h w/m. ˚c fluid thermal conductivity k -nusselt number nu -reynolds number re=( h.umax)/ ѵ re -richardson number ri=gr/re² ri m radius(r=15cm) r -dimensionless frequency s=ω.h/umax s ˚c dimensional value of the temperature t ˚c cold wall temperature tc ˚c hot wall temperature th sec time t ˚c temperature difference thtc toδ -dimensionless time period tw m/s top cover speed (amplitude of the oscillation) umax m dimensional length of the yaxis y m width of the enclosure w greek letters m²/s thermal diffusivity α 1/ o k thermal expansion coefficient β dimensionless time τ=(t.umax)/h τ m²/s kinematic viscosity v kg/m.s dynamic viscosity μ kg/m³ density ρ rad/s angular frequency ω=2πf ω 6. references [1] f.p. incropera, “convection heat transfer in electronic equipment cooling”, j. heat transfer 110 (1988) 1097–1111. [2] jae-weonjeong, and stanley a. mumma, “impact of mixed convection on ceiling radiant cooling panel capacity” ,international journal of hvac&r research, vol. 9, no. 3, july 2003. [3] j.srinivasan, “solar pond technology”, sadhana, vol. 18, part 1,1993, pp. 39–55. [4] o. aydin and w.yang, “mixed convection in cavities with a locally heated lower wall and moving sidewalls”, numerical heat transfer, part a, 37:695 –710, (2000). [5] g. guo, m. a.r. sharif, “ mixed convection in rectangular cavities at various aspect ratios with moving isothermal sidewalls and constant flux heat source on the bottom wall”, int. j. of heat and mass transfer, 43: 465–475, (2004). [6] h. f. oztop, i. dagtekin, “mixed convection in two-sided lid-driven differentially heated square cavity”, international journal of heat and mass transfer 47 :1761–1769, (2004). [7] a. al-amiri, k. khanafer, j. bul, i. pop, “effect of sinusoidal wavy bottom surface on mixed convection heat transfer in a liddriven cavity”, international journal of heat and mass transfer 50: 1771–1780, (2007). [8] m.a.r. sharif, “laminar mixed convection in shallow inclined driven cavities with hot moving lid on top and cooled from bottom”, appl. therm. eng. 27 :1036–1042, (2007). nabil j. yasin al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 3246 (2014) 45 [9] m.a. waheed, “mixed convective heat transfer in rectangular enclosures driven by a continuously moving horizontal plate”, international journal of heat and mass transfer 52 (2009) 5055–5063. [10] k.m. khanafer, a.m. al-amiri, i. pop, "numerical simulation of unsteady mixed convection in a driven cavity, using an externally excited sliding lid" , eur. j. mech. b fluids 26 (2007) 669–687. [11] ghasemi, b.,andaminossadat, s., “comparison of mixed convection in a square cavity with an oscillating versus a constant velocity wall heat transfer”, numerical heat transfer, part a , 54:726743,(2008). [12] chin-lung chen and chin-hsiang cheng, “experimental and numerical study of mixed convection and flow pattern in a liddriven arc-shape cavity”, heat mass transfer (2004) 41: 58–66. [13] md. n. h. khan chowdhury, sumonsaha and md. a. hassan mamun, “mixed convection analysis in a lid driven trapezoidal cavity with isothermal heating at bottom for various aspect anglers”, international conference on mechanical engineering 2628 december (2009). [14] j.p.holman"experimental methods for engineers "mcgraw-hill book company,1984 [15] yunus, a., “heat transfer: a practical approach”, second edition, mcgraw-hill, (2003). [16] abdull,a.s" mixed convection in an enclosure with a heated lower wall and reciprocating moving upper wall"m.sc thesis ,tech.college of baghdad 2013. (2014) 3246، صفحة 1، العدد10دمجلة الخوارزمي الهندسية المجل نبيل جميل ياسين 46 للحمل المختلط داخل مغلف ذو سطح علوي متحرك بارد وسطح سفلي ساخن تجريبية دراسة ***اياد سليمان عبد هللا ** علوان ضياء الدين حسين * نبيل جميل ياسين بغداد -ةالهندسي ةالتقني ةالكلي /التبريد ةقسم هندس **،* موصل -ةالهندسي ةالتقني ةالكلي /التبريد ةقسم هندس *** nabiljamil58@yahoo.com: البريد االلكتروني* dhia716@yahoo.com:البريد االلكتروني** ayad_s00@yahoo.com :االلكترونيالبريد *** الخالصة من درجة أعلىثبتت درجة حرارة السطح السفلي للحيز المغلق لتكون . الهواء داخل حيز مغلق تمت دراسته تجريبيا إلىانتقال الحرارة بالحمل المختلط الفرق بدرجات الحرارة للسطحين العلوي . حرارة السطح العلوي وحرك السطح العلوي بحركة ترددية ثابتة، فيما تم عزل السطحين الجانبيين حراريا ق يمكن تغيير نسبة طوله تم استخدام صندو. والسفلي غيرت عدة مرات لتتم المراقبة الدقيقة للتوزيع الحراري داخل الحيز المغلق مع تغير عدد ريجاردسون تم عرض مخططات . الى ارتفاعه كحقل اختبار لغرض تحديد تأثير عدد ريجاردسون ونسبة الطول الى االرتفاع على شكل الحركة الهوائية داخل الحيز بة الطول الى االرتفاع بثبوت عدد أظهرت النتائج ان معدل عدد نسلت يزداد مع نس. كنتورية لحركة الهواء ومعدل عدد نسلت داخل الحيز في هذا العمل . نقصان عدد ريجاردسون يقلل من الفترة الزمنية بثبوت نسبة الطول الى االرتفاع إنكما . ريجاردسون mailto:nabiljamil58@yahoo.com <4d6963726f736f667420576f7264202d20d3dacf20d8c7e3ed20e6cce3c7e120e6e1edcb35342d203633> al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 14, no. 4, decmber, (2018) p.p. 5463 design and implementation of an automatic control for two axis tracking system for applications of concentrated solar thermal power saad tami hamidi* jamal abdul-kareem mohammed** laith muhsin reda*** *,**,***department of electromechanical engineering / university of technology * email: saadtami@yahoo.com ** email: jamalshwesh@gmail.com *** email: mohsen.laith12@yahoo.com (received 26 september 2017; accepted 10 january 2018) https://doi.org/10.22153/kej.2018.01.010 abstract the present work presents design and implementation of an automated two-axis solar tracking system using local materials with minimum cost, light weight and reliable structure. the tracking system consists of two parts, mechanical units (fixed and moving parts) and control units (four ldr sensors and arduino uno microcontroller to control two dc servomotors). the tracking system was fitted and assembled together with a parabolic trough solar concentrator (ptsc) system to move it according to information come from the sensors so as to keep the ptsc always perpendicular to sun rays. the experimental tests have been done on the ptsc system to investigate its thermal performance in two cases, with tracking system (case 1) and without tracking system (case 2). the experimental results showed that the average solar radiation falling on the ptsc prototype in the two cases during the same time was 854 and 701 watt/m2, respectively, which means an increase in the solar radiation about 21.8 % when using tracking system. it was found that the average useful heat gain output of solar collector was equal to (376.2, 252.6 watt) for the two cases, respectively, so there was an increase of about 48.9 % when using the tracking system. also, the average thermal efficiency of the ptsc was found to be (20.7, 26.5 %) for the two cases, respectively, which means an increase in the average efficiency by 28% with use of tracking system compared to the fixed case. keywords: arduino, tracking system, solar collector. 1. introduction solar tracking system is very important technology, utilized in the advancement of solar energy applications, especially in the high power solar concentrator which directly transfer the solar energy into electrical or thermal energy. solar tracking precision with high degree is requested to guarantee that the solar collector is capable of utilization the peak solar energy during the daytime. solar concentrator with high power, like parabolic trough, central receiver system, parabolic dish, etc are commonly used in the collecting solar energy applications. the solar trackers follow the track of sun in the horizontal and vertical plane. for the sake of this capabilities, the two axis trackers output higher power than the single axis trackers. roth, et al. [1] designed a two axis solar tracker. this tracker enables to get automated measure for forthright solar radiation with a pyrheliometer. the tracker, in the active mode of operation, utilizes the signal come from a sun detecting linear sensor for controlling the pointing. to direct the instrument platform, two stepper motors were used, making the sunrays falling on the center of the sensor. mamlook, et al. [2] designed and implemented a two axis solar tracker. a saad tami hamidi al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 5463 (2018) 55 programmable logic controller plc was used to direct the two axis sun tracking surface. the results were compared with the fixed system case at a surface tilted 32o to the south. initially test measurements pointed out that using the two axis solar tracker would daily elevate the thermal energy collection more than 40%. sungur [3] proposed a dual axis tracking system using formulas to calculate the solar azimuth and altitude angles yearly for an interval of one year. khan, et al. [4] had designed and built a sun tracking system controlled by microcontroller. the tracker senses the sunlight intensity via light dependent resistors (ldrs) to be utilized for driving stepper motors to direct the photovoltaic (pv) panels according to the sun position. pineda and arredondo [5] designed and carried out a two axis sun tracking system. the tracker senses the peak brightness light point in the sky by building a sensor based on a geodesic dome. yousif [6] presented a mechatronic tracking system to follow the sun position depending on four sensors mounted on the solar panel frame. a microcontroller atmega16l was used to control the system. it was found in this study that the output power gain for the two axes solar tracking panel was 31.5% more than the fixed solar panel. sadyrbayev, et al. [7] designed a two axis sun tracking system, with four photo resistors, controlled by lm324n microcontroller. the results showed that the solar tracker system generated a 31.3% higher power. parabolic trough solar concentrator ptsc system for water heating is one of various technologies that excellently confirm solar energy. it, commercially, has been used to generate high pressure steam in the power generation units. also, it could be used in residential and commercial applications with small scale [8]. a small scale generation system could be utilized to generate a process heat with intermediate temperatures reaches 150°c. this temperature is enough for most processes of small factories, like paper production, food canning, sterilization, air-conditioning, refrigeration, etc. the thermal performance of this kind of sun concentrator could be enhanced highly via using one of the sun tracking topologies to concentrate the sunrays on the focal point. basically, the tracking action depends on the axis of the sun beam reflector. a comparative investigation for various modes of tracking had been studied comprehensively in the literature [9,10]. these studies demonstrated that adopting the two axis tracking mechanism will lead to highly increase in the output of the system energy and enhances the contribution in solar energy. it had been described in the literature that the two axis sun tracker dissipates more energy than the single sun tracker because of the additional power control requirement. so, utilizing the two axis technique cannot be considered except if the quantity of produced energy is compensating to the extra elements and cost of maintenance. the aim of this work is to design and implementation of a microcontroller based twoaxis sun tracker to direct the ptsc prototype consciously toward the sun to enhance its thermal performance. an experimental study is carried out on the prototype to evaluate the system thermal performance under the local climate. 2. modes of tracking generally, there are two modes of tracking for the ptsc; single axis tracking and two axis tracking. the two axis tracking follows both of the sun's changing azimuth and sun's changing altitude to focus the parallel sunrays falling on the reflectors perpendicularly on the receiver tube, while the single axis tracking collector is directed to a north-south and follows the sunrays from east to west as shown in fig. 1 (a, b and c). fig .1a. one axis tracker fig.1b. two axis tracker saad tami hamidi al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 5463 (2018) 56 fig.1c. azimuth and solar altitude angles. fig. 1. modes tracking system [11]. a tracking mechanism must be reliable and able to follow the sun with a certain degree of accuracy, come back the thermal collector at the end of daytime to its initial location, and also track the daylight when it is cloudy. fixed collectors producing heat or electricity all year round are usually fixed and tilted at an angle equal to the installation site latitude which directly opposing the sun. therefore, the thermal energy accumulated by the solar collector during both summer and winter is less because of the sun's changing altitude. the use of the tracking mechanism elevates the amount of solar energy received by the solar collectors resulting higher output power. initially, the ptsc is a flat plate with linear tube collector placed on the mechanical structure of the tracking system. a solar photovoltaic pv panel might be mounted on the ptsc frame in order to capture the entire light incident on it and converts it into electrical energy required for the tracking action. to stabilizes the solar pv panel electric output and minimizes any fluctuations in the current and voltage values, a charge controller must be directly connected to the pv panel. this controller charges the battery with dc power to its maximum potential. an arduino "microcontroller based board" is used to control all the system processes to be implemented as expected. the arduino takes analogue input from light dependent resistances sensors ldrs and supplies the servomotors with electric power. according to the location of the sun, the arduino controller analyses the signals come from the ldrs. the ldrs' resistance and thus the value of current flowing into the arduino is varying, depending upon which of the two facing ldrs has higher falling light on it. the voltage variation is then converted into input signals driving the motors. two motors are mounted on the ptsc axes, responsible for the dual-axis movement of the tracking system. this causes the ptsc system to tilt in the direction of the ldr causing decrease in its resistance to the lowest value and hence, guarantees fall the maximum sunrays on the ptsc. this noticeably, raises the amount of light energy captured and then transferred into heat energy. 3. hardware implementation of tracking system the tracking system is mainly consisting of two parts, mechanical unit and electrical control unit. 3.1 mechanical unit the mechanical unit of the tracking system consists of fixed part and moving part. the fixed part, called the base, is very important to fix the whole concentrator system on it. the moving part is responsible to provide two types of motions of axial and tilting. the axial motion is employed to move the collector from east to west. this movement is the most effective in the solar tracking system. the movement in this direction is done via using a 12v, 0.1a dc gear box as shown in fig. 2a. the tilting motion is utilized to drive the collector to upper and lower. this movement can be directed by using a 24v, 0.42a dc motor to produce a linear movement. this motor is installed on the moving part of the ptsc system using welding and rotates through bolts as shown in fig. 2b. fig. 2a. dc gear box (axial motion). saad tami hamidi al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 5463 (2018) 57 fig. 2b. dc motor movement (tilting motion). 3.2 control unit the control circuit consists of, arduino uno, four light dependent resistances (ldrs) and four channel relay circuit. the arduino uno is a board electronic development; comprise of an electronic circuit open source with a microcontroller based single board. it is programmed by a computer and designed to make the process of utilizing interactive electronics in multidisciplinary projects more easily. four ldrs were used in order to sense the solar radiation and track the movement of the sun and in order to make solar radiation perpendicular to the collector. the ldr resistance depends on the intensity of the radiation falling on them, the more the intensity of the radiation incident, the less resistance, and the lower the intensity of the radiation falling on this resistance, the greater the resistance. this is to take advantage of this feature when changing the value of resistance while changing the intensity of the radiation falling on them. the current flowing through them will change and thereby change the voltage on the resistance according to ohm's law. fig. 3 shows the connection of the ldrs to the arduino uno and 10kω resistance for the purpose of voltage divider necessary for the process of the solar tracking. fig. 3. ldr connecting with arduino uno [12] four channel relay circuit board is used to run the dc motors, used for directing the solar tracking process, via connecting this circuit between the arduino and the motors. the circuit is fed from a 6v dc source. the relay circuit receives the electrical signals coming from the arduino; its work is depending on the software loaded on the arduino microcontroller. to supply the dc motors and the water dc pump in the ptsc system with the required electric power, a 12v, 13w solar pv panel, 12v 12ah sealed lead acid battery, and 12v charge controller should be used. the block diagram in fig. 4 shows operation steps the two axis tracking system. the tracking process can be demonstrated as in the flowchart shown in fig. 5. saad tami hamidi al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 5463 (2018) 58 fig. 4. block diagram of the two axis tracking system. fig. 5. flow chart of the two axis tracking process. saad tami hamidi al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 5463 (2018) 59 4. design of the solar pv panel the pv panel used as a self dc power supply to fed the two dc motors as well as a water pump without the need to external ac power supply. the pv panel power can be designed depending on the electrical specifications of the motors and water pump used and the time duration of the pv panel through the daytime. the design of the pv panel power was carried out on date 24/3/2016. the operation time was from the sunrise time at 7:03am to sunset time at 5:26pm. the system uses two dc motor to move the ptsc system in the x-axis and y-axis directions, and the 12v dc water pump to recycle the water in the system. the axes motors were permitted to move two seconds every quarter of an hour, through the whole running time. while the water pump was running continuously. table (1) shows current, voltages, power, running time and energy for each motor used in the system. this table represents the rated values of all motors as well as the calculations necessary for designing the pv panel and thus specify the required dc battery and the charge controller. table 1, operation values for the dc motors device current(a) voltage(v) power (w) operation time (hour) consumed energy (w.h) x-axis motor axial motion 0.1 12 1.2 0.02307 0.027 y-axis motor tilting motion 0.42 24 10.08 0.02307 0.232 water pump 1 12 12 10.383 124.6 ʃ 10.42914 124.859 the total pv cell power for this design = ���.����. � .������� � = 11.972 w. the value of the energy required that is enough to supply the tracking system with electricity is: ���.����. ��� = 10.4 a. h. as a result, a 12v, 13w pv panel is enough to be used for charging a 12v, 12ah battery. this will be appropriate for supplying enough electric power to the whole system, without need for external electrical sources. 12v, 10a charge controller could be used to charge the battery. 5. description of the parabolic trough solar collector the ptsc system has major components; reflector, receiver, support structure, working fluid circulation system and tracking system. the reflector was coated with polished aluminium sheet (0.5 mm thickness) having reflectivity of 0.87. a receiver tube of copper material was coated with black zinc having absorptivity of 0.94. thin layer of coating was used so as to minimize the resistance of heat flow through the coat to the pipe and to the working fluid. support structure was built using steel to provide strong mechanical support against high wind speed and harsh environmental conditions. table (2) contains all the dimensional specifications of the ptsc and other parameters. table 2, ptsc system specifications item value / type collector aperture area 1.612 m2 aperture width 1m length-to-aperture ratio 1.755 rim angle 90° receiver diameter 0.025 m tracking mechanism type electro-optical mode of tracking two axes tracking concentration ratio 10.5 focal length 0.250 m 6. experimental setup and instrumentation the experimental setup is shown in fig. 6. saad tami hamidi al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 5463 (2018) 60 (a) (b) fig. 6. experimental setup (a) frame, (b) ptsc the experimental setup consists of the ptsc directed by a tracking system and combined with a storage water tank. a tank of 40 litres capacity kept at 0.5 m above the ptsc level to maintain natural flow of working fluid (water) inside the ptsc with close loop and without loading water. in this experiment, the water temperature at inlet, outlet and ambient was measured using thermometers (model: btm-4208sd), sensor type k thermocouple. the water mass flow rate of (20 l/h) has been measured using flow meter. the water has specific heat of 4.2 kj/kg.oc. a solar meter (model: tes-1333r data logging solar power meter) used to measure the intensity of solar radiation during time interval (9am-3pm) according to tilt angle for the ptsc. the ptsc system was directed by the tracking system controlled by an arduino uno controller board. the solar energy radiation sensors are mounted on the ptsc frame and send electric signals to the control circuit. the control circuit converts these signals to specified motors via a drive circuit to direct the ptsc toward the sunlight. these motors, in turn, direct the location of the ptsc when peak sun radiation intensity is received at the aperture. these motors were supplied with the required power from a 12v, 12ah dc battery, charged via a 12v, 13w solar pv panel. the pv panel was designed according to the electrical energy required to feed two dc motors and a dc circulating water pump. the dc motion motors are programmed to move for 2sec after each stop of 15 min during the daily work period, while the water pump works continuously to circulate water through the collector. the measurements of (solar radiation, inlet water temperature to receiver tube, outlet water temperature from receiver tube) were carried out every hour through time daily from (9am-3pm). the useful heat gain (the amount of heating absorbed by working fluid) and the thermal efficiency of the ptsc were determined according to the measurements parameters and they can be obtained from equations (1)-(4): ... (1) ... (2) c inletoutletp ai ttcm )( * − =η ... (3) n ave  = η η)( ... (4) 7. results and discussion fig. 7 shows the variation of the average solar radiation intensity measured in the 26 of april 2016 using solar meter at the fixed case (without using tracking system) of the ptsc and in the 27 of april 2016, the average intensity solar radiation on the same ptsc was measured using two-axis tracking system. the figure shows that the solar radiation increases as day passes from morning to noon and gradually reduces after 12:30pm. in the case of non tracking system, the solar radiation available was in the range of (580 890 w/m2). while it was found that the solar radiation available was in the range of (735 922 w/m2), when using two-axis tracking system. it could be concluded from this figure that the average obtained solar radiation for the fixed collector during interval time daily (9am-3pm) was (701 w/m2), while with tracking system, the average solar radiation become (854 w/m2). this means an increase in solar radiation about (21.8 %) when using tracking system compared with the fixed )(* inltouletpu ttcmq −= n q q u aveu  =)( saad tami hamidi al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 5463 (2018) 61 case. fig. 8 shows the effect of solar radiation on receiver outlet temperature of water in the 26 of april 2016 at the fixed case of the ptsc and in the 27 of april 2016 at the tracking case. from the figure, it can be shown that the outlet temperature of the water is gradually raised from morning to noon and gradually reduced after 12:30pm when the outlet temperature is in the range (28.474.3oc). the average value of outlet temperature is 59.5oc through time daily from (9am-3pm) for non-tracking system. in the case of tracking system case, the outlet temperature of water was in the range (36.3-89.5oc) and the average value of outlet temperature through time daily reaches up (73.3 oc). from the figure, it can be concluded that there is an increase in the outlet temperature of the water about (23%). also, it is noted from the figure, that the outlet water temperature rises gradually until 12:30 then begins to drop because of the solar radiation falling on the solar collector decreases and shadow effect of the grooves of the absorber surface which reduces the energy collected and increases thermal losses from the solar collector. also, it was observed that during morning, all radiation was readily absorbed by receiver tube, so mean tube temperature and outlet water temperature increase at minimum heat loss. fig. 9 shows the useful heat gain in the 26 of april 2016 at the fixed case of the ptsc and in the 27 of april 2016 at the tracking case. it can note that the useful heat gain of the solar collector for non-tracking system has an average value reaches up to 252.6 watt through time daily from (9am-3pm), while it reaches to 376.2 watt for tracking system case, through the same time interval. this means an increase of about 48.9% when using tracking system for solar collector compared with the fixed case. fig. 10 shows the instantaneous efficiency of the solar collector during daylight hours in the two cases of tracking. it is noted a gradual increase in efficiency due to cold water at the beginning of the day, this due to a gradual increase of the heat gain until the time 12:30 and after that it starts decrease gradually. from this figure, it is noted that the average efficiency of the solar collector during time daily between (9am-3pm) for non-tracking system reaches up to (20.7%), while, with using tracking system, the average value of efficiency reaches (26.5%). this means the increase of about (28%) when using tracking system for solar collector as compared with fixed system case. fig. 7. solar radiation with time on the (26th and 27th) april 2016 fig. 8. outlet temperature with time on the (26th and 27th) april 2016 fig. 9. useful heat gain with time on the (26th and 27th) april 2016 fig. 10. thermal efficiency with time on the (26th and 27th) april 2016 0 200 400 600 800 1000 1200 8 10 12 14 16 time daily (hr) s o la r ra d ia ti o n ( w /m 2 ) without tracker with tracker 0 10 20 30 40 50 60 70 80 90 100 8 10 12 14 16 time daily (hr) t e m p e ra tu e r o u tl e t (c 0 ) without tracker with tracker 0 100 200 300 400 500 600 700 8 10 12 14 16 time daily (hr) u s e fu l h e a t g a in ( w a tt ) without tracker with tracker 0 10 20 30 40 50 8 10 12 14 16 time daily (hr) t h e rm a l e ff ic ie n c y % without tracker with tracker saad tami hamidi al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 5463 (2018) 62 8. conclusions this paper focuses on the design and implementation of an automatic control for two axis tracking system for the applications of the concentrated solar thermal power. a parabolic trough solar concentrator is proposed to be used for generation a hot water suited for domestic and industrial process heat applications. from experimentation and thermal performance evaluation, the following conclusions are drawn: the incident solar radiation and the mode of tracking system are very important parameters which directly affect the performance of the ptsc. using the tracking system to direct the ptsc to the sunrays enhanced the solar concentrator performance. the concentrator has been generate a hot water up to 89 c0 and raised the average instantaneous efficiency of the ptsc to 23% when using two-axis tracking comparing with the fixed system. nomenclature abbreviation meaning of abbreviation ac aperture area (m2) cp specific heat capacity of water at constant pressure (kj/kg.k) i solar radiation (watt/m2) � ∗ mass flow rate (kg/s) n number of reading measurement qu useful heat gain (watt) qave average useful heat gain (watt) tinlet fluid inlet temperature (°c) toutlet fluid outlet temperature (°c) η thermal efficiency (%) ηave average thermal efficiency (%) 9. references [1] p. roth, a. georgiev, and h. boudinov, “cheap two axis sun following device.” energy conversion and management vol. 46, no. (7-8), 2005, pp. 1179-92. [2] r. mamlook, s. nijmeh, and s. m. abdallah, “a programmable logic controller to control two axis sun tracking system”, information technology journal vol. 5, no. 6, 2006, pp.1083-1087. [3] c. sungur, “multi-axes sun tracking system with plc control for photovoltaic panels in turkey”, renewable energy, april 2009, vol. 34, issue 4, pp.1119–1125. [4] t.a. khan, s.m. shahrear tanzil, r. rahman, s.m. shafiul alam, “design and construction of an automatic solar tracking system”, 6th international conference on electrical and computer engineering icece, 18-20 december 2010, pp. 326-329. [5] f. pineda, and c.a. arredondo, “design and implementation of sun tracker prototype for solar module positioning”, ieee, 2011, pp.2905-2910. [6] a.h. yousif, “study of sun tracking mechanism for photovoltaic panels”, msc. thesis, mechatronic engineering, university of salahaddin-erbil, 2012. [7] s.a. sadyrbayev, a.b. bekbayev, s.o. and z.z. kaliyev, “design and research of dualaxis solar tracking system in condition of town almaty”, middle-east journal of scientific research volume 17, issue 12, 2013, pp. 1747-1751. [8] a. fernandez-garcıa, e. zarza, l. valenzuela, and m. perez, “parabolic-trough solar collectors and their applications. renewable and sustainable energy reviews”, 14, 2010, pp.1695-1721. [9] h. mousazadeh, a. keyhani, a. javadi, h. mobli, k. abrinia, and a. sharifi, “a review of principle and sun-tracking methods for maximizing solar systems output,” renewable and sustainable energy reviews, 13, 2009, pp. 1800-1818. [10] m. koussa, a. cheknane, s. hadji, m. haddadi, and s. noureddine, “measured and modelled improvement in solar energy yield from flat plate photovoltaic systems utilizing different tracking systems and under a range of environmental conditions,” applied energy, vol. 88, no. 5, 2011, pp.1756-1771. [11] national renewable energy laboratory, solar radiation data manual for flat plate and concentrating collectors (1962-1990), u.s. department energy 1992. [12] w. durfee, arduino microcontroller guide, university of minnesota version. oct-2011. )2018( 54-63، صفحة 4، العدد14دالمجلجلة الخوارزمي الهندسية م شكري حميد غضيب 63 الحرارية الشمسية الطاقة لتطبيقات محورينذاُت تبعتَ ةمونظمل آلي محكّ تَ تنفيذو صميمتَ كزةرَّ المُ ***ليث محسن رضا **جمال عبد الكريم محمد *سعد طامي حميدي قسم الهندسة الكهروميكانيكية / الجامعة التكنولوجية ****،**، saadtami@yahoo.com* البريد األلكتروني: jamalshwesh@gmail.com :البريد األلكتروني ** yahoo.com12mohsen.laith@*** البريد األلكتروني: الخالصة ً وزن خفوأ بأقل كلفة وتنفيذها أستخدام مواد محليةمحوريين ب اتذ ذاتية الحركة شمسيتتبع ة ممنظوالعمل الحالي تصميم و مثل يُ . موثوقية بناءو ا ldrوئية من نوع ض اربعة متحسساتمن ( الكهربائية التحكم ووحدات) والمتحركة الثابتة األجزاء( الميكانيكية الوحدات :جزأين من تتألفالتتبع ة ممنظو ُ تأتي م ثنائية المحاور التتبع ةمونظم إنّ ) .التيار المستمرب يعمالن الحركة نوع ذاتي أردوينو الذي يقوم بالسيطرة على محركييننوع دقيق سيطروم ةالئمت ُ لكي الضوئيةلمتحسسات القادمة من ا حسب المعطياتبو الُمركز لتحريك مكافىءال القطعي ز الشمسي ذركّ مع المُ سوية ةعتمجمُ و بشكل الشمسى ركزبقى المُ ت بأستخدام(الحالة األولى) في حالتين: داء الحراريم األيوالشمسي لتق ركزعلى المُ يةرباألختبارات التججريت أعلى االشعة الساقطة من الشمس . عمودياً دائم في يالشمس ركزمُ شعة الشمس الساقطة على الأعدل ن مُ بأ ية المستحصلةبيرَبّينت النتائج التجها. ستخداماعدم عند (الحالة الثانية) و التتبع الشمسي ةممنظو . لقد التتبع ةمونظم% عند استخدام ٢١٫٨اع الشمسي حوالى عش) وهذا يعني زيادة في معدل األ٢واط/متر ٧٠١ و ٢واط/متر ٨٥٤(على التوالي هي الحالتين واط) وهذا يعني زيادة حوالى ٢٥٢٫٦ واط و ٣٧٦٫٢( على التواليهي وللحالتين أعالهلمدة نفسها الشمسي ل ركزمُ للكتسبة ممعدل الحرارة المفيدة ال ُوجدَ بأن ) وهذا %٢٠٫٧و %٢٦٫٥في حالتي التتبع كانت على التوالي ( الشمسي ركزمُ لل الحرارية عدل الكفاءةمُ أن كما وجد بالتتبع و ةمونظمعند استخدام % ٤٨٫٩ .بالمقارنة مع المنظومة الثابتة وراالتتبع ثنائي المح ةموظمنعند استخدام % ٢٨يعني زيادة بمقدار <4d6963726f736f667420576f7264202d20cfdac7c120e6ddd1decf20e6e3cde3cf20c7e1d3d1c7cc38332d203931> co-digestion of shumblan with different wastes as a source for the biogas production duaa a. farhan* farkad a. lattieff** mohammed a. atiya*** * ,***department of biochemical engineering/ university of baghdad ** department of energy engineering/ university of baghdad *email: eng.duaa1990@yahoo.com **email: farkad400@yahoo.com ***email: mohatiya1965@gmail.com (received 13 march 2018; accepted 30 april 2018) https://doi.org/10.22153/kej.2018.04.004 abstract shumblan (sh) is one of the most undesirable aquatic plants widespread in the irrigation channels and water bodies. this work focuses on boosting the biogas potential of shumblan by co-digesting it with other types of wastes without employing any chemical or thermal pretreatments as done in previous studies. a maximum biogas recovery of 378 ml/g vs was reached using shumblan with cow manure as inoculum in a ratio of 1:1. the methane content of the biogas was 55%. based on volatile solid (vs) and c/n ratios, biogas productions of 518, 434, and 580 ml/g vs were obtained when the shumblan was co-digested with food wastes (sh:f), paper wastes (sh:p), and green wastes (sh:g) respectively. no significant changes of methane contents were observed during the anaerobic co-digestion of shumblan with the selected wastes. this noticeable increments of biogas yields proved that this sort of biomass can be utilized as a promising source for bioenergy production of industrial scale because of its economic operation. slight ph variations indicated that the codigestion performance has a good stability operation and no excessive amounts of volatile fatty acid were accumulated. the results also proved that by using co-digestion technology, the biodegradation of shumblan plants could be significantly accelerated supplying greater amounts of biogas yields. moreover, the appropriate co-digestion with other wastes gave the shumblan high digestibility and, hence, there will be no need to prior pretreatment in order to boost the biogas yield. keyword: aquatic macrophytes, shumblan biomass, anaerobic co-digestion, biogas. 1. introduction aquatic plants (cerathophyllum demersum) are one of the biggest challenges facing aquatic life and causing stress freshwater around the irrigation channels. however, the uncontrolled and rapid growth of aquatic plants has also caused other environmental dangers such as foul odor, interference with navigation, deoxygenation of water, water stagnation and increasing mosquito breeding sites [1]. shumblan, as it known in the middle east area, is one of these unwanted plants, which comprise floating, emergent, and submerged aquatic macrophytes. to solve the slow degradation of cellulose and lignin, most previous studies used high ratios of inoculums in order to provide optimum conditions for the successful operation of anaerobic digestion [2-4]. more extended research activities have been carried out using chemical or thermal pre-treatments processes to accelerate the hydrolysis of lignin, which in turn leads to improve the anaerobic digestion conditions toward increase the biomethane yield [5-11]. due to their high content of cellulose and lignin, few researchers have investigated the use of shumblan toward bioenergy production. nonetheless, the literature has recognized several key factors in the biochemical composition of algal biomass affecting biogas production, such as moisture content, ash content, lignin, fraction lipids, al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 14, no. 4, december , (2018) p.p. 8391 duaa a. farhan al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 8391(2018) 84 carbohydrates and proteins [12]. laura et al. [13] studied the energy recovery from macro-algae (c.demersum) using anaerobic digestion process. her research exhibited that the methane yield was 554 ml ch4/gm vs. in general, the range of aquatic biomass yield is wide, starting from 100 to 500 ml ch4/gm vs, if this biomass yields methane more than 400 – 450 ml ch4/gm vs it provided a high yield and could be viable for industrial use. anaerobic co-digestion may be capable to be a successful alternative for increasing the biodegradability of the macrophytes, which can, in turn, increase the biogas production. co-digestion of shumblan with other wastes gave a more optimal substrate mix in this regard, however, interestingly, a stable process was observed even with a c/n ratio within the range of 20-30 [14]. for adjusting c/n ratio, zehan et al. [15] used activated sludge as a co-waste in co-digestion with macrophytes biomass. however, no study has investigated the potential of the co-digestion of macrophytes biomass with other types of co-substrates such as food, green or paper wastes. this study explored an alternative way to employ anaerobic digestion of shumblan biomass without chemical or thermal pretreatments and could be feasible to the bioenergy plant operation. by using appropriate alternative technology, codigestion of aquatic macrophytes biomasses with other wastes maybe presented a promising method for reducing effectively the operation cost and increasing the volumetric biogas yield, based on volatile solid concentrations and c/n ratios. the selected wastes for co-digestion with shumblan were food waste, paper waste, and green waste as well as the cow manure as inoculum. 2. materials and methods 2.1 feedstock and inoculum free-floating shumblan plants were harvested locally from irrigation channels in the university of baghdad. the collected species were dried in the sun for two weeks to obtain biomass products for the proposed biogas batch experiments. then, the biomasses of shumblan were shredded using electric blender up the sizes of particles of 5 mm were formed by using molecular sieve. based on the volatile solid and c/n ratios, food wastes, paper wastes, and green wastes were added to the shumblan and compared their biogas output with that yield from the shumblan alone. as inoculum, cow manure was blended with the feedstock in a ratio of 1:1 (based on vs). it was used in its dry state after 7 days of storage at 30oc to minimize its content of biodegradable materials that probably influences the biogas results [16]. total solid (ts) and volatile solid (vs) were determined according to the standard method aoac 2000 [17] and c/n contents were measured by element analyzer equipment (table.1). table1, characteristics of the used wastes sample symbol ts% vs% vs/ts% c/n shumblan biomass sh 83.6 49.9 59.68 14 food waste f 31 27.2 87.7 24 green waste g 19 15 78.95 25 paper waste p 92.2 79 85.7 136 cow manure cw 32 23 72 16 to accelerate the degradation of shumblan, designed and recommended loadings of shumblan with the other wastes that were mixed for anaerobic co-digestion were reported in table.2. loading rates of high and low volatile solid concentrations were treated taking into account the adjusted c/n values. as stated earlier, the same ratios of cow manure were blended to the co-digested substrates as shown in table.2. table2, mixing ratios of co-digestion of shumblan. sample mixing ratio vs (gm/l) cow manure vsgm /l c/n sh:f 1:1 6.5 6.5 22.02 sh:f 5:1 15.6 15.6 17.81 sh:p 2:1 6.5 6.5 21.67 sh:p 3:1 20.8 20.8 19.97 sh:g 1:2 6.5 6.5 19.17 duaa a. farhan al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 8391(2018) 85 2.3 experimental design as shown in the figure. 1, 500 ml batch reactors were used as batch digesters to carry out the anaerobic digestion tests under mesophilic conditions. after blending the required amounts of inoculum and substrate, each digester was filled with water up to 400 ml and was labeled with its composition. then the digesters were purged with nitrogen gas for 5 min to provide the anaerobic condition before it was tightly closed with their covers. the digesters were conducted at 40oc using a water bath shaker in a constant vibration rate of 80 rpm. biogas measurement was carried out using water displacement method (fig.2). the ph value of each digester was recorded before and after each experiment with a ph meter (wtw co., germany, inolab 7110). all the samples were duplicate and the results given were mean values. to measure the methane content in the generated biogas, gas analyzer was used (biogas5000, england, g502483). fig. 1. used digesters in this work. fig. 2. biogas volumetric measurement device. 3. results and discussion 3.1 anaerobic digestion of the shumblan the results of biogas yield for three different volatile solid concentrations of shumblan biomass are shown in fig.3. the results showed that the sh at vs concentration of 6.5, 25, and 50 (gm/l) generated cumulative biogas of 378, 277, and 170, respectively. that is, the lower the volatile solids, the greater the biogas production. these results confirm that shumblan can be a feasible source for biogas extraction when a proper volatile solid concentration was used. after 15 days of digestion time, a significant increase in biogas rate from shumblan was observed due to its compositions of lignocellulose and lignin that needed a longer time to degrade completely [18]. however, it was observed that the generation of biogas was mostly completed in range between 70 and 90 days. this difference in digestion time can also be attributed to the lower water content, which is necessary for the microorganisms to break down the cellulose and lignin into small soluble materials [19]. this result (378 ml/gmvs) was slightly lower than 417 ml/gmvs obtained with macrophytes algae by pugliese et al. [20]. pastare et al. [21] reported higher biogas production (471 mlch4/gmvs) with higher c.demersum/inoculum ratio of 1:10. this high biogas produced may be due to a higher amount of inoculum [21]. thus, using different c.demersum/inoculum ratios led to a significant variance of biogas production, since the kinetic behavior of the inoculum was different with the higher concentration presented in the substrate. table 3 shows the results of ph values and methane composition for each sample. it was found that the values of ph were not changed significantly before and after each digestion process. this indicated that there was no accumulation of excess volatile fatty acid (vfa). moreover, this stability of ph during the digestion process provided an excellent environment for methanogenic bacteria performance. table 3 also demonstrated that the composition of methane content ranged between 55 to 64 %. the highest methane content was not synchronized with highest biogas production. the highest methane composition was generated with highest vs content. this can be attributed to the excess formation of acetate, which is main source for methane production. duaa a. farhan al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 8391(2018) 86 fig. 3. accumulative biogas production of three different concentrations of shumblan. table 3, ph values and methane compositions of shumblan sh (gm vs/l) phi phf ch4 % 6.5 8 8.5 55 25 7.5 7.24 54.4 50 8 7.58 64 3.2 anaerobic digestion of the additive wastes the results of the biogas production for food, green, and paper wastes were curved in fig. 4.3 together with shumblan for comparison. all experiments were run at a vs concentration of 6.5 gm/l. a maximum biogas production was at the food waste after 41 days (1070 ml/gmvs); this was due to the larger water soluble materials (sugars, proteins, lipids) rathere than complex compounds (cellulose and lignin). however, the food waste digester started the biogas generation on the 4th day of the digestion time. on the 26th day, there was a sharp increase in the biogas production rate, indicating that an increase in the activities of the methanogenic bacteria. green and paper wastes delivered biogas rates of 333 and 97 ml/gmvs after a digestion time of 61 and 70 days, respectively. green wastes showed a slightly lower cumulative biogas production to that of shumblan. in contrast, the biogas released from paper wastes proved lower results than those of the other substrates. paper waste had less biogas productivity because paper waste containing cellulose, hemicellulose, pectin and lignin are very difficult to biodegradable and their hydrolysis step takes longer time [22]. it was noted that the paper waste released a significant biogas rate after 33 days of the digestion time. hence, the hydrolysis step is often considered as the rate-limiting step when utilizing these kinds of substrates [23]. although shumblan wastes contain lignocellulose material, as it exists in the green and paper wastes, the productivity of its biogas also was higher during the same period. fig. 4 accumulative biogas production for food, paper, green and shumblan wastes this result can be attributed to the higher content of lipids and rich nutrients such as carbon, nitrogen and phosphorus, which are essential nutrients for anaerobic microorganisms [24]. methane content and ph values for each waste are listed in table 4. it can be seen that the food waste have highest percent of methane followed by that of green, shumblan, and paper wastes. this is because; the quality of the biogas depends on several parameters such as the composition of the treated waste, c/n ratio, and the lignin content [25]. in general, food waste has larger water soluble materials such as sugar, proteins, and fats than those available in the materials of the origin plant. consequently, the biodegradation of the organic wastes would be shifted toward acetic acid formation rather than toward generation of co2 and h2 gases during acetogensis stage [17]. as in the case of shumblan, phi and phf values were kept in a slight differences, indicating that the anaerobic digestion was performed under stable conditions. table 4, ph and methane composition values of used substrates sample gm vs/l phi phf ch4 % f 6.5 8 8 70 p 6.5 7.5 7 50 g 6.5 7.5 7 56.5 sh 6.5 8 8.5 55 duaa a. farhan al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 8391(2018) 87 3.3 co-digestion of the shumblan with food wastes the results of the co-digestion of shumblan with food waste are depicted in fig.5. accumulative biogas productions from sh:f substrates with 1:1 ( 6.5 gmvs/l) and 5:1 (15.6 gmvs/l) mixing ratios were 518 and 77 ml/gmvs, respectively. unexpected divergence in rates of biogas production were observed for both sh:f mixtures. compared with the digestion of sh alone, the biogas yield from sh:f (1:1) was higher by 36% . as for the sh:f (5:1), the biogas yield was less by 86%. although the high volatile solid content of sh:f mixture shows a lower biogas yield, the presence of excess lignocelluloses and lignin can significantly affect the anaerobic digestion of the sh biomass. on the other hand, adjusting c/n ratios resulted in an increase in biogas yield from sh:f (1:1) compared to sh alone which indicated a higher microorganism activates was performed. however, there was no significant change in ph values indicating that no excess amounts of fatty acids were formed during acidogensis step (table.5). as for the digestion time, the results show that both two mixtures needed lower time compared to shumblan. the fast hydrolysis step for the sh:f (1:1) sample and the low water content for the sh:f (5:1) sample was the main reason for this variable digestion time. table. 5 showed that in all the experiments the methane content was between 53-56% of the total biogas released. these values were lower than obtained by the digestion of food waste alone and close to that obtained by the shumblan alone. this may be attributed of releasing additive gases (co2, nh3 and h2s) during the digestion process when the shumblan had co-digested with the food wastes. koyama et al. [26] reported that in co-digestion experiment of submerged microphyted and food wastes, more biogas released as the food wastes increased. under various macrophyte to food waste ratios, he demonstrated that the addition of the food waste dropped ph of the sample, which provided better conditions for the digestion process, but at the same time food waste is inhibited due to the release of dissolved lignin. krustok et al. [27] established a co-digestion experiment for microalgae with food waste. they showed that replacement of 12% food wastes with microalgae released biogas higher than the proportion of 25 and 37%. this decrease could be caused due to the consumption of food wastes as bacteria feed at the same time the algal biomass converted to biogas. fig. 5. accumulative biogas production from sh:f substrates table 5, ph values of sh:f substrates sample wt. of vs phi phf ch4% sh:f (1:1) 6.5 7.2 7.93 53 sh:f (5:1) 15.6 7.02 7.63 56 3.4 co-digestion of the shumblan with paper wastes the biogas yields during the co-digestion of the shumblan with paper waste are shown in fig.6. accumulative biogas productions from sh:p substrates with 2:1 ( 6.5 gmvs/l) and 3:1 (20.8 gmvs/l) mixing ratios were 434 and 158 ml/gmvs, respectively. both sh:p (2:1) and sh biomass showed comparable behavior of biogas yield during the first 18 days of digestion time, but less for sh:p (3:1). at the end of the digestion, the biodegradability of sh:p (2:1) increased by 15% than that of the shumblan at the same concentration of the volatile solid (6.5 gm/l). sh:p (3:1) released biogas yield less by 74% than that of the shumblan. this variance in biogas yield can be attributed to the high cellulose materials in paper wastes, which need high amounts of water to degrade them. this demonstrates that the use of the high-level amount of the paper wastes affected the biogas production in spite of adjusting its c/n ratio. moreover, it is concluded that it is difficult to optimize the biogas production from the shumblan biomass depending on the c/n ratio alone. digestion time results show that less time is required for the sh:p 2:1 (56 days) compared with shumblan (70 days) due to the best adjusting of its c/n ratio. for the case of the sh:p (3:1), it can be seen that longer time (90 days) is still required because of the slow hydrolysis step. ph values were not changed significantly confirming the stability of the co-digestion operation when the paper waste was added to the shumblan (table. 6). a slight decrease of methane duaa a. farhan al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 8391(2018) 88 content was observed in released biogas for both sh:p substrates compared with sh, indicating that the methanogenic bacteria are most likely inhibited due to the formation of ammonia [17]. the average methane contents of the biogas yield from sh:p at the two 2:1 and 3:1 were 51% and 49%, respectively. this lower methane content of the sh:p indicated that there was an inhibition to methanogenic microorganisms. no literature surveys are available to compare the result of this study with them. fig. 6. accumulative biogas production from sh:p substrates table 6, ph values of sh:p substrates sample wt. of vs phi phf ch4 % sh:p (2:1) 6.5 7 8 51 sh:p (3:1) 20.8 7 7.99 49 3.5 co-digestion of the shumblan with green wastes fig. 7 shows the results of biogas yield rates for the co-digestion shumblan with green wastes (sh:g). it can be seen that the biogas production of sh:g (2:1) substrate rapidly released from day 2. higher biogas production rate with sh:g substrate was observed probably because green waste is more easily degradable than the shumblan. after 70 days of digestion time, the biogas yield of sh:g was 580 gmvs/l, which were remarkably higher by 53% than that from the shumblan alone, confirming this co-substrate (green waste) is highly applicable for the co-digestion with shumblan. koyama et al. [28] reported that the intracellular soluble organic matters (e.g.cytosols) exist in the cell wall of lignocellulosic materials maybe responsible for this increase in the biogas yield. however, adjusting c/n ratio provided a better nutrients source for the microorganisms to be more active for the biogas recovery. the biogas yield of sh:g was relatively high as compared with the other substrates. the ph values before and after the digestion process remained almost constant between 7 and 7.5 indicating the stability of the digestion operation and this little increase in ph value can be attributed to the release of ammonia. in this work, all experiments showed a slight increase of ph between 7 and 8 because of the increase of ammonia as a result of hydrolysis from shumblan and co-substrates. on the other hand, methane conversion (54%) in this experiment was in a close range to that obtained from the shumblan alone. it is worth to mention that the order of the biogas yield rates can be arranged in the following sequence; sh:g > sh:f > sh:p > sh. this increase in biogas production among these mixtures can be also interpreted due to the variances in vs/ts ratios and to the origin nature of the added substrates. the results of this work obviously show that the addition of food, paper, and green wastes improves the feasibility for anaerobic digestion of the shumblan. fig. 7. accumulative biogas production of sh:p and sh 4. conclusion the results showed that the addition of food, paper, and green wastes to the shumblan significantly increased the biogas production up to 53% as in the case of sh:g co-digestion. moreover, anaerobic co-digestion of shumblan could be applicable without the need to use other pre-treatment operations. sh:g has the highest biogas yield followed by that of sh:f and then sh:p. based on the vs, the biogas yield decreased with increasing the vs concentration. based on biogas quality, the shumblan waste and its mixtures showed similar results compared to the shumblan alone. the approached constant of ph values for all duaa a. farhan al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 8391(2018) 89 the co-digestion experiments indicated good stability of these processes. generally, the study demonstrated that the co-digestion of shumblan and food, paper, and green wastes could be a competitive option for improving the volumetric biogas yield. 5. references [1] escobar, m. m., voyevoda, m., fühner, c., & zehnsdorf, a. 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[22] ofoefule, a. u., nwankwo, j. i., & ibeto, c. n. (2010). biogas production from paper waste and its blend with cow dung. advances in applied science research, 1(2), 1-8. duaa a. farhan al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 8391(2018) 90 [23] taherzadeh, m. j., & karimi, k. (2008). pretreatment of lignocellulosic wastes to improve ethanol and biogas production: a review. international journal of molecular sciences, 9(9), 1621-1651. [24] montingelli, m. e., tedesco, s., & olabi, a. g. (2015). biogas production from algal biomass: a review. renewable and sustainable energy reviews, 43, 961-972. [25] bagudo, b. u., dangoggo, s. m., hassan, l. g.and garba, b. (2010). influence of catalyst (yeast) on the biomethanization of selected organic waste materials. nigerian j. of basic and applied sci 2010;2: 209-212. [26] koyama, m., nakahashi, n., ishikawa, k., ban, s., & toda, t. (2017). anaerobic codigestion of alkali-pretreated submerged macrophytes and acidified food waste for reduction of neutralizing agents. international biodeterioration & biodegradation, 125, 208213. [27] krustok, i., nehrenheim, e., odlare, m., liu, x., & li, s. (2013). cultivation of indigenous algae for increased biogas production. in international conference on applied energy, icae2013, pretoria, south africa. [28] koyama, m., yamamoto, s., ishikawa, k., ban, s., & toda, t. (2014). anaerobic digestion of submerged macrophytes: chemical composition and anaerobic digestibility. ecological engineering, 69, 304309. )2018( 8391، صفحة 4العدد، 14دجلة الخوارزمي الهندسية المجلم دعاء علي فرحان 91 الحيوي الغاز إلنتاج كمصدر المختلفة النفايات مع (الثنائي) للشمبالن المشترك الهضم ج***محمد عبد عطية السرا **فرقد علي لطيف ن*دعاء علي فرحا جامعة بغداد كلية الهندسة الخوارزمي/ /قسم الهندسة الكيميائية االحيائية***،* جامعة بغداد كلية الهندسة/ / قسم هندسة الطاقة** yahoo.com1990eng.duaa@البريد االلكتروني: * yahoo.com400farkad@البريد االلكتروني: ** gmail.com1965mohatiya@البريد االلكتروني: *** لخالصةا طة سامرغوب فيها المنتشرة في قنوات الري واالجسام المائية. يركز هذا العمل على تعزيز امكانية الغاز الحيوي بوالالشمبالن احد النباتات المائية غير يعد از الحيوي باستعمال معالجة كيميائية او حرارية كما في الدراسات السابقة. اعلى قيمة النتاج الغ ةخلط الشمبالن مع انواع مختلفة من المخلفات بدون استعمال اي ً لقاحبوصفه مع سماد البقر ٣٧٨ملم/غم متطاير الشمبالن النسب الصلبة المتطايرة و إلى واستناداً . ٪ ٥٥ الحيوي الغاز من الميثان محتوى . كان١:١بنسبة ا عندما تم خلط الشمبالن مع مخلفات االطعمة ملم/غم متطايراً ٥٨٠ و ، ٤٣٤ ، ٥١٨ الحيوي الغاز إنتاج على الحصول النتروجين ، تمنسبة الكاربون الى رى. الزياداتوالورق والحشائش ،على التوالي. لم يالحظ اي تغيير في محتوى الميثان خالل عملية الهضم الالهوائي المشترك للشمبالن مع المخلفات االخ النتاج الطاقة على النطاق الصناعي بسبب عملها االقتصادي اً مصدربوصفه الملحوظة في انتاج الغاز الحيوي اثبتت امكانية استخدام هذا النوع من الكتلة الحيوية الى اثبتت النتائج كما حماض االمينية. اشارت التغيرات الطفيفة في قيمة الرقم الهيدوجيني الى ان عملية الهضم الالهوائي مستقرة جيدا ولم يحصل تراكم لالو الهضم االهوائي ان ،ذلك نع فضالً استعمال تقنية الهضم الالهوائي يؤدي الى تسارع تحلل النبات بشكل كبير ممايؤدي الى زيادة في انتاج الغاز الحيوي . ان المشترك مع المخلفات االخرى يعطي للشمبالن قابلية هضم عالية مما يؤدي الى تعزيز في انتاج الغاز الحيوي. al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 1223 (2013) thermo-rheological investigation and modeling of the shear viscosity of polypropylene above the melting temperature ammar al-baldawi* shatha k. muallah** olaf wünsch*** *,***institute of mechanics / university of kassel / kassel / germany **department of biochemical engineering / al-khawarizmi college of engineering / university of baghdad *email: ammar@uni-kassel.de **email: shatha_engr@yahoo.com ***email: wuensch@uni-kassel.de (received 13 may 2013; accepted 3 december 2013) abstract the increasing use of polymeric materials in the daily life, leads to challenges in the processing industry to deliver high performance materials with affordable terms. however, new processing techniques lead to high costs. in order to reduce processing costs it is necessary to understand the non-newtonian behavior of the polymers in their molten state to be able to simulate the processes before the construction of the plants starts. here the shear thinning behavior of the viscosity of polymeric melts is essential. thus, this paper deals with the experimental investigation of the thermorheological behavior of the viscosity of one of the most used polymers (polypropylene) over a wide range of temperatures and shear rates. furthermore, a modeling approach of the viscosity via a generalized non-newtonian law combined with an arrhenius model is done. keywords: polymer melt, polypropylene, thermo-rheological modeling, generalized newtonian fluid, cross model, shear viscosity, shear thinning behavior, rotational rheometer, high-pressure capillary rheometer, 1. introduction polymer processing techniques are divided into two fields. the first is the polymeric material production techniques e.g. deriving polymeric ingredients from by-products formed during the refining process of crude oil. however, this field is a chemical motivated field where the polymeric materials are investigated in their macroand microscopic ingredients. in case of polypropylene (pp) the macromolecules are set together by monomer propylene. the long molecule structures of pp are made of olefin chains and the small molecule structures are broken olefin structures and are bounded together by covalent bonding mechanisms. however, it is well known that the physical and mechanical properties of polymers are strongly influenced by the size or length of the chains. e.g. increasing the chain length leads to enhancement of the melting temperature point due to more joints between the chains [1,2]. the chemical bonding mechanism and the ingredients of pp are shown in the chemical structural equation in fig. 1. fig. 1. polymerization of propylene to polypropylene[3]. mailto:shatha_engr@yahoo.com ammar al-baldawi al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 1223 (2013) 13 the melting point of polypropylene ranges from 160°c to 171°c, for perfectly isotatic pp the melting point is 171°c and for commercial isotatic pp it ranges from 160°c to 166°c. however, these melting points are an advantage of pp in comparison with the polycarbonates family, where the melting point is in the region of 240°c. the properties and the fields of application of pp are given in table 1. table 1, benefits and areas of application of pp [1-3]. usage benefits of pp areas of application  act as an excellent insulator  electric industry  microchip industry  very low moisture absorption (water resistant)  the surface structure is antibacterial  color miscible  non-toxic  clinical use  home facilities  packaging industry  toys industry  law density  high toughness  stiffness and elastic flexibility at high temperatures  security devices in automobile and aircraft industry  lightweight technologies independent of all pros and cons of the chemical and physical properties of pp the material characteristic needs to be understood. therefore the second field is the knowledge about the thermo-rheological properties of pp. this is very important for the process engineers. producing usual pp components such as mentioned in table 1 need to be understood in such a way that the preliminaries experiments of the processes are bounded due to the reduction of cost and time. the rheological quantities are introduced in order to characterize the rheological behavior of pp as all other non-newtonian fluids or respectively as non-newtonian polymer melts [4-6,8,9]. however, a lot of complex phenomena are investigated in the field of non-newtonian polymers such as: shear thinning, elastic and relaxation, elongation hardening and softening and normal stress differences behavior, refer to [20,21]. these phenomena take place in the context of simulation procedures of complex flow simulation of such processing techniques. the main information indeed is the knowledge about the shear viscosity since it is possible for small deformation rates to take the information about the elongation viscosity with the so-called trouten-ratio [7]. furthermore, it is possible to introduce a time parameter with the help of a generalized newtonian model. it is possible to introduce big changes of the so-called zero shear rate viscosity by varying the temperature. in polymer processing this can help to save energy, since low pressure gradients in engineering apertures are needed. therefore, this paper deals with the thermo-rheological investigation of the shear viscosity of pp in a temperature region of 170°c to 300°c and a shear rate of 0.001 1s to 1000 1s . these regions are usually used in processing engineering. 2. experimental investigation the experimental work was done with two different types of rheometer systems. the first system is specialized for low shear rates and gives little error oscillations during the moment measurements. this system is the ar-g2 rotational rheometer form the ta-instruments company as shown in figure 2. for controlling the friction of the system during the rotation, the use of the ta-instruments calibration software is preferred. for the preparation of the specimens the use of the heating oven and the camera was helpful. however, the preparation is done via setting the desired measurement temperature slowly, for example setting the temperature above 170°c means heating the specimen till 50°c under nitrogen atmosphere (10 l/min) with a waiting time of 10 min, then increasing the temperature by c10t  and waiting for 1 min at each of the steps till 170°c. by increasing the measurement temperature e.g. above 200°c, it is preferred to increase the waiting time, this also helps as a ammar al-baldawi al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 1223 (2013) 14 drying process of the polymer specimen. in the case of polypropylene the drying process needs to be increased at the very beginning of the measurement processes for high temperatures. this leads to a longer waiting time at a temperature of 50°c. fig. 2. ar-g2 (ta-instruments) rotational rheometer with the used plate-plate geometry. in this work the so-called plate-plate geometry is used to introduce a very homogeneous specimen form, as shown in figure 3. here some measurements where benchmarked with the coneplate geometry. all benchmark measurements showed good agreements. the measurement of the viscosity is obtained from the given angle movement velocity with h r  …(1) and the measured moment m with the shear stress  and the given shear viscosity can be calculated with     3 2 r m  . …(2) fig. 3. plate-plate (a) and cone-plate (b) system, where m is measured and is the given angle movement of the upper plates (r radius of the plate and h is the height of the specimen, note 1ˆ h ), refer to [7]. in case of the high shear rates viscosity measurements the use of the high-pressure capillary rheometer is important. figure 4 shows the principle of the measurements. plate-plate geometry heating oven (-10°c to 600°c) camera and light ammar al-baldawi al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 1223 (2013) 15 fig. 4. sketch of a capillary rheometer. the fluid is pressed with a piston-cylinder system through a capillary tube. the difference of the pressure p between inlet and outlet of the tube is measured in connection with the volume flux v , see therefore figure 4 and 5. these quantities are used to calculate two new variables, a weighted flow rate v d q  3 32   …(3) and the wall shear stress l dp w 4   …(4) the correlation between the flow rate and the wall shear rate under stationary condition in a tube results from the balance of momentum and reads   w dq w    0 24  . …(5) integration by parts leads to the real shear rate at the wall q d qdd w w              )(log )(log 3 4 1 2    …(6) this relation is called rabinowitsch-weissenbergcorrection [19]. afterwards the shear viscosity is calculated by w w      . …(7) the used apparatus is shown in figure 5. around the specimen cylinder is attached a heating oven for temperatures between 20°c and 400°c. furthermore, at both ends of the cylinder pressure and temperature sensors are located. fig. 5. rheograph 20 (rg20 göttfert) high-pressure capillary rheometer. for each rheometer a minimum of 3 experiments are made for the same temperature. the results are shown in figure 6 and 7, where the viscosity (measured for low and high shear rates) is shown over the shear rate for a given temperature. the measurements are noted with r for rotational rheometer and k for high-pressure capillary rheometer. as shown in the figures there is a good agreement between multiple independent measurements at the same heating oven pressure and temperature sensor transmission piston specimen cylinder ammar al-baldawi al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 1223 (2013) 16 temperature. furthermore, the measured viscosities are obtained more successfully in the transition domain of the rotational rheometer compared with the capillary rheometer. it is also shown that the capillary rheometer has some troubles to measure the viscosity at low shear rates due to oscillations. additionally in the case of a temperature above 280°c and 300°c the viscosity starts to be low and the measurement via a rotational rheometer has its limitation, because here the polymer melt starts to flow out of the geometry. this leads to a decrease in the viscosity measurements as shown in figure 7. fig. 6. measurements of the shear viscosity of pp at a temperature region of 170°c to 260°c. 1 100 10000 1000000 0.001 0.01 0.1 1 r1_pp 170°c r2_pp 170°c 1 100 10000 0.001 0.1 10 1000 r1_pp 180°c r2_pp 180°c k1_pp 180°c k2_pp 180°c k3_pp 180°c k4_pp 180°c k5_pp 180°c k6_pp 180°c k7_pp 180°c 1 100 10000 0.001 0.1 10 1000 r1_pp 200°c r2_pp 200°c r3_pp 200°c k2_pp 200°c k3_pp 200°c k4_pp 200°c k5_pp 200°c k6_pp 200°c 1 100 10000 0.001 0.1 10 1000 r1_pp 220°c r2_pp 220°c r3_pp 220°c k1_pp 220°c k2_pp 220°c k3_pp 220°c k4_pp 220°c 1 100 10000 0.001 0.1 10 1000 r1_pp 240°c r2_pp 240°c r3_pp 240°c r5_pp 240°c k1_pp 240°c k2_pp 240°c k3_pp 240°c 1 100 10000 0.001 0.1 10 1000 r1_pp 260°c r2_pp 260°c r3_pp 260°c r4_pp 260°c k1_pp 260°c k2_pp 260°c ammar al-baldawi al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 1223 (2013) 17 fig. 7. measurements of the shear viscosity of pp at a temperature region of 280°c and 300°c. 3. modeling approaches beside the experimental investigation, it is well known that the increasing use of computational fluid dynamic packages (cfd) are used to understand the complex polymer melt flow in complex mechanical and processing devices which needs some usable material modeling techniques. for this aim it is essential to model the behavior of the polymeric material precisely. however, commercial cfd packages deliver only some linear models (e.g. the newtonian model: a linear viscose body model for viscose fluids [11,12]). for incompressible fluid flow simulations all cfd packages start from the continuity and momentum equation [7] ,0 v …(8)   . t fsvvv           …(9) here v is the eulerian velocity field,  denotes the fluid density, s is the cauchy stress tensor and f are body forces. in order to simulate the accurate material behavior the stress tensor s needs to be modeled. furthermore, to introduce the shear dependency in the material model in order to model the experimental observed shear thinning behavior it is possible to use a so-called cross model. the cross viscosity model is a good generalization of the constant newtonian viscosity. doing so leads to the well known structure of the cauchy stress tensor s for the incompressible fluids, refer to [8,10,13,14] .t1s  p …(10) here, p denotes the static pressure and t is the viscose stress tensor and can be written as ,),(2 dt    …(11) where the viscosity depends on the shear rate  and the temperature  . furthermore, d   t .2/1 vv  is the symmetric part of the gradient of the eulerian velocity field v . however, to reproduce the material behavior ),(   needs to be fitted on the measurements. in this work the generalized cross model [16,17] with an arrhenius type temperature dependency was used ,: ))((1 )( ),( 0 dd            n …(12) the zero shear rate viscosity )( 0  is given by the exponential arrhenius model . 15.273 1 15.273 1 )()(0                     kkr e exp r0 0 rr …(13) in eq. (13) )( rr  is a reference viscosity at a reference temperature. however, the reference values in this work are set at the minimum measurable temperature with the experimental setup at r = 170°c  spa19000)( rr  . 1 100 10000 0.001 0.01 0.1 1 10 100 r1_pp 280°c r2_pp 280°c r3_pp 280°c k2_pp 280°c k3_pp 280°c 1 100 10000 0.001 0.01 0.1 1 r1_pp 300°c r2_pp 300°c r3_pp 300°c ammar al-baldawi al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 1223 (2013) 18 furthermore, mol/kj70000e0  and  kmol/j314.8r0  are the activation energy of pp and the universal gas constant. the time function )( is modeled by the same type of arrhenius model with the reference value 1 rr 85.0)(  s , see [15-18]. . 15.273 1 15.273 1 )()(                     kkr e exp r0 0 rr …(14) in case of fitting the cross model without the arrhenius models of eq. (13) and (14) the results are shown in fig. 8 and the parameters are given in table 2. fig. 8. averaged experimental results (symbols) and fitted lines with the cross model on each temperature step without using the arrhenius models. table 2, parameters of the cross model obtained for each temperature step. note that the * noted parameters are estimated due to the lake in the measurements, since high shear measurements were not done for all temperatures.  0  n 170 19000 0.85 0.68* 180 12500 0.45 0.68 200 8000 0.33 0.68 220 4000 0.15 0.68 240 1800 0.038 0.68 260 1000 0.025 0.68 280 600 0.019 0.68* 300 250 0.012* 0.68* both the zero shear viscosity and the time constant depend highly on the temperature. the exponent n is constant. using the arrhenius models leads to a good agreement with the cross parameters in table 2, this fact allows to use the viscosity model given in eq. 12, as shown in table 3 and figure 9. table 3, parameters of the cross using the arrhenius models.  0  0/ n 170 19000 0.85 4.474e-5 0.68 180 12493 0.5589 4.474e-5 0.68 200 5696.16 0.25483 4.474e-5 0.68 220 2767.99 0.12383 4.474e-5 0.68 240 1422.91 0.06366 4.474e-5 0.68 260 768.901 0.0344 4.474e-5 0.68 280 434.404 0.01943 4.473e-5 0.68 300 255.402 0.01143 4.475e-5 0.68 10 100 1000 10000 0.001 1 1000 pp 170°c pp 180°c pp 200°c pp 220°c pp 240°c pp 260°c pp 280°c pp 300°c cross 170°c cross 180°c cross 200°c cross 220°c cross 240°c cross 260°c cross 280°c cross 300°c ammar al-baldawi al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 1223 (2013) 19 fig. 9. the arrhenius models used for fitting the zero shear rate viscosity and the time parameter  of the cross model. a deeper analysis of the experimental data in table 3 shows, that the quotient of the time function and the zero viscosity for each temperature is constant. then it is possible to rewrite the cross model (12) in the form        .10474.4 )( 1 1),( 5 0 00 constc c n                 …(15) with this relation the shear behavior of pp for all melt temperatures can be described by a master viscosity function [18] in dependence of the product of shear rate and the related temperature dependent zero viscosity plotted black in figure 10. fig. 10. the master viscosity curve (black line) of the measured temperature and shear dependent viscosity. note that here the cross model curves where used from figure 6. 200 4200 8200 12200 16200 170 220 270 experiment model 0 0.2 0.4 0.6 0.8 1 170 220 270 experiment experiment model ammar al-baldawi al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 1223 (2013) 20 as shown in figure 10 the mastered cross model is able to reproduce the viscosity function in the whole temperature interval with one constant, see therefore table 3. this approach allows the modeling and simulation of isothermal production processes with a dimensionless parameter set. furthermore it deliver first information and predictions of the thermo rheological process simulation. 4. discussion and conclusions in order to characterize the thermo-rheological behavior of polymer melts in a wide area of shear rates it is necessary to use a multi set of experimental stations, e.g. the rotational rheometer and the high-pressure capillary rheometer. furthermore, it is important to make the measurements in a nitrogen atmosphere in order to avoid oxidation processes of the polymer molecules. in this work the use of 10 l/min volumetric flow rate of nitrogen shows good results and it was not necessary to increase this rate. for high temperatures the high-pressure capillary rheometer was not able to measure the shear viscosity due to the fact of low zero shear rate viscosity. however, it is very hard for the rotational rheometer to get better results, due to the fact of drifting phenomena out of the plateplate geometry. it is also supposed that polymer melts show the same softening e.g. shear thinning behavior for high shear rates even at different temperatures. in order to characterize the thermo-rheological behavior it is important to understand the socalled preloads techniques of the rotational rheometer to introduce a stationary shear flow in the polymer sample. doing so leads to better results at the very beginning of the measurements or in e.g. at very small shear rates. furthermore, for measuring the gap between the rotational rheometer and the capillary rheometer it is important to know that the capillary rheometer measurements takes incredible experimental time and the fluctuation of the zero shear rate viscosity. due to these facts it is more useful to start the capillary measurements in a shear rate region above 5[1/s]. by increasing the shear rate, the capillary rheometer starts to return good results without oscillating. the modeling approaches for isothermal and non-isothermal processes can be used to provide a close representation of the measurements. in fact it is possible to use the mastered cross model both for isothermal and non-isothermal processes. in case of using the arrhenius model for the temperature dependent zero viscosity it is important, beside the continuityand momentum equation (8) and (9), to take the energy equation into account. it is well known that polymeric melt shows also so-called elongation hardening and softening behavior. furthermore, it is known that such melts are highly elastic and this needs to be modeled via a viscoelastic maxwell-like model. here, the shear viscosity modeling would be implemented in the viscoelastic model without change. therefore equation (11) would be extended with the elastic contributions. it is also important to model the real relaxation time, because the time constant in equation (12) and (14) is only mimicking a fluid own time where the shear thinning behavior starts to occur. in this way it is not a real relaxation time. however, this would be included in future work. acknowledgments the authors would like to thank m. eigenbrod and s. descher (university of kassel) for the careful experimental investigation of pp at the high-pressure capillary rheometer and the helpful work in the laboratory. furthermore, the authors thank the german research foundation (dfg) and the university of bagdad for the financial support. list of symbols w , shear rate [s -1 ] r the radius of the plate-plate geometry and the sample [m]  angle velocity of the plate-plate geometry [radius/s] h hight of the sample [m]   , viscosity and the viscosity function [pas] m measured moment [nm] q weighted flow rate [s -1 ] v flow rate (volume flux) [m 3 /s] d diameter of the tube of the capillary rheometer [m] w , shear stress and wall shear stress [n/m 2 ] p pressure gradient [bar] l length of the tube of the capillary rheometer [m]  density of the fluid [kg/m 3 ] ammar al-baldawi al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 1223 (2013) 21 v euler velocity field [m/s] s cauchy stress tensor [n/m 2 ] f specific volume forces [nm 3 /kg] 1 unity tensor p pressure [bar] t extra viscous stress tensor [n/m 2 ] d rate of deformation tensor [s -1 ]  temperature [°c] )(0  zero shear rate viscosity )( rr  reference viscosity )( time parameter function [s] )( rr  reference time parameter 0e activation energy constant of pp [kj/mol] 0r the universal gas constant [j/mol k] r reference temperature 5. references [1] c.maier, t.calafut, polypropylene: the definitive user`s guide and data book, isbn: 9781-1-884207-58-7, plastic design library, new york (1998) [2] r. zhuet et al, microstructure and mechanical properties of polypropylene/poly(methyl methacrylate)nano composite prepared using supercritical carbon dioxide, macromolecules, 44, 6103-6112 (2011) [3] j. aho, rheological characterization of polymer melts in shear and extension: measurement reliability and data for practical processing, tampere university of technology, tampere, finland (2011) [4] z. mohamed ariff et al rheological behavior of polypropylene through extrusion and capillary rheometry, isbn:987-953-51-0636-4, university sain malaysia, malaysia (2012) [5] r. s. smith, j.a. glasock, measurement of the rheological properties of standard reference materials2490 using an in-line micro-fourier rheometer, korea-australia rheology journal, 16-4, 169-173 ( 2004) [6] s. shanabhag, analytical rheology of polymer melts: state of art. isrn material science, department of scientific computing, florida state university , tallahassee-usa (2012) [7] a. al-baldawi, modellierung und simulation viskoelastischer polymerschmelzen, isbn: 978-3-89958-598-8, kassel university press, kassel (2012) [8] a. al-baldawi, o. wünsch, some new aspects of the invariants of the rate deformation tensor and their application on viscoelastic polymer melts, technischemechanik, 32-6, 667-683 (2012) [9] a. al-baldawi, o. wünsch, numerical simulation of highly viscoelastic polymer melts using vf and devss methods, proceedings in applied mathematics and mechanics, 11, 563-564 (2011) [10] a. al-baldawi, l. schreiber, viscoelasticplastic modelling and experimental investigation of three different batches of 51crv4 stell, technischemechanik, 31, 114 (2011) [11] a. al-baldawi, h. damanik, s. turek, o. wuensch, comparison of improved fe/fv methods in the context of simulating jet extrusion processes, proceedings of the 1st int. con. on thermo-mechanically graded materials, isbn: 978-3-942267-58-8, 225230 (2012) [12] a. al-baldawi, o. wünsch, simulating of a pressing process of a viscoelastic polymer melt, proceedings in applied mathematics and mechanics, 12, 471-472 (2012) [13] a. al-baldawi, l. schreiber, o. wünsch, hysteresis behaviour of 51crv4 and viscoplastic modeling aspects, proceedings in applied mathematics and mechanics, 11, 349-350 (2011) [14] a. al-baldawi, l. schreiber, o. wünsch, experimental investigation, viscoelasticplastic modelling and parameter identification for different batches of 51crv4 steel, proceedings in applied mathematics and mechanics, 10, 273-274 (2010) [15] p. j. carreau, rheological equations from molecular network theories, journal of rheology, 16:99127 (1972) [16] m. m. cross, kinetic interpretation of nonnewtonian flow, journal of colloid and interface science, 33-1, 30-35 (1975) [17] a. w. sisko, the flow of lubricating greases, journal of industrial and engineering chemistry, 50-12, 17891792 (1958) [18] g. böhme, strömungsmechanik nichtnewtonscher fluide. b.g. teubner, stuttgart, 2000 [19] r. bird, r. armstrong, o. hassager, dynamics of polymeric liquids, wiley inter-science, new york, 1987 [20] a. al-baldawi, o. wünsch, experimental investigation and modeling approaches of ammar al-baldawi al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 1223 (2013) 22 the elongation viscosity of polycarbonate above the glass transition temperature, proceedings of the polymer processing society 29th, annual meeting, pps-29, s22-14 (2013) [21] m. krebs, o. wünsch, development and testing of a new pressure cell for rheological characterisation of polymer melts, applied rheology, 20, 23229 (2010) (2013) 1223، صفحة 4، العدد9مجلة الخوارزمي الهندسية المجلد عمار محمد البلداوي 23 أالنصهارجة لزوجة ألقص من ألبولي بروبيلين فوق درجة ذلريولجية ونمالحرارية ا لتحقيقا ***اوليف فينش** شذى كاظم عبد اللطيف* البلداوي محمد عمار المانيا/ جامعة كاسل / كلية الهندسة / قسم الهندسة الميكانيكية ***،* جامعة بغداد/ كلية الهندسة الخوارزمي / قسم الهندسة الكيميائية االحيائية ** ammar@uni-kassel.de : االلكتروني البريد ** shatha_engr@yahoo.com : اللكترونيا البريد** wuensch@uni-kassel.de : االلكتروني البريد *** الخالصة .ةويؤدي الى التحديات في صناعة تجهيز لتقديم مواد عالية األداء مع شروط معقول ,د البوليميرية في الحياة اليوميةأالستخدام المتزايد للموا من أجل الحد من تكاليف التجهيز فمن الضروري تفهم سلوك الغير النيوتونية .تؤدي الى ارتفاع التكاليفلجديدة لك فان تقنيات المعاجة اذومع ة البوليمرات هنا سلوكية رقيق القص للزوج .بدء باحتساب العملياتمن البوليرات في حالتها المنصهرة للمقدرة على تفهم محاكاة التجهيز قبل ال ه الورقة تتناول التحقيق التجريبي للسلوك الحرارية الريولوجية للزوجة لواحد من البوليمرات األكثر ذوبالتالي ه. المنصهرة أمر ضروري جة من اللزوجة من خالل اقانون ذلك تم نهج النمذعالوة على .من درجات الحرارة ومعدالت القص على مجموعة(بولي بروبيلين)شيوعآ . أرينيوس جذللموئع الغير نيوتونية جنبا الى جنب مع نمو mailto:ammar@uni-kassel.deالبريد mailto:ammar@uni-kassel.deالبريد mailto:shatha_engr@yahoo.com mailto:wuensch@uni-kassel.deالبريد mailto:wuensch@uni-kassel.deالبريد effect of location and type of al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 8, no. 1, pp 4864 (2012) effect of construction joints on performance of reinforced concrete beams zena waleed abass department of civil engineering/ college of engineering/ university of almustansirya (received 18january 2011; accepted 31 may 2011) abstract construction joints are stopping places in the process of placing concrete, and they are required because in many structures it is impractical to place concrete in one continuous operation. the amount of concrete that can be placed at one time is governed by the batching and mixing capacity and by the strength of the formwork. a good construction joint should provide adequate flexural and shear continuity through the interface. in this study, the effect of location of construction joints on the performance of reinforced concrete structural elements is experimentally investigated. nineteen beam specimens with dimensions of 200×200×950 mm were tested. the variables investigated are the location of the construction joints (at midspan or at third point of the specimens), type of construction joints (vertical, inclined, and key construction joints), and presence of stirrups at these joints. the specimens were tested using 1000 kn computer controlled versatile electronic testing machine. the specimens were positioned in the machine so that the deflection at center and\or at the location of construction joint was measured at each load step. the results of the experimental program indicated that the best location of the construction joint is at the point of minimum shear. it was found that the use of vertical construction joint has little effect on the overall behavior of beam specimens (the percentage of reduction in ultimate load capacity is in the range of 0% 5%). while inclined construction joints results in a noticeable reduction in strength of beams relative to the strength of beam without construction joint the percentage of reduction in ultimate load capacity is in range of 8% 20%.the presence of stirrups at the construction joints is an important variable, which affect the type of failure and load carrying capacity. it is found that adding of stirrups across the joint results in an increase in capacity in the range of (7%15%) and a decrease in deflection in the range of (20%48%). keyword: construction joint, reinforced concrete, beams, cracks in concrete. 1. introduction joints are necessary in concrete structures for variety of reasons. not all concrete in a given structure can be placed continuously, so there are construction joints that allow for work to be resumed after a period of time. since concrete undergoes volume changes, it can be desirable to provide joints and thus relieve tensile or compressive stresses that would be included in the structure. it is necessary then to provide various types of joints in most concrete structures, and in order that these joints adequately perform the functions for which they are intended, it is essential that they be installed and located correctly (1) . 1.1. joints in concrete structures when joints are installed in a concrete structure, it is essential that they do not impair the normal functions of the structure and usually it is desirable that they should blend with the general appearance. in general, it is convenient to classify the various types of joints in two groups (2) : zena waleed abas al-khwarizmi engineering journal, vol. 8, no. 1, pp 4864 (2012) 49 a. functional joints these joints are installed to accommodate movement (volume change) due to temperature, shrinkage during setting, expansion, sliding, warping ... etc. b. construction joints these joints are made when there is a break stoppage in the construction program. construction joints are stopping places in the process of placing concrete and they are provided to simplify construction of a structure. the location of construction joints depends on the type of work, the site condition and the production capacity of the plant or labor employed. it frequently happens; when large volume of concrete are being placed that there is a break in the construction work. pure construction joints are not intended to accommodate movement but they are merely separation between consecutive concreting operations and in fact, every effort is directed towards preventing movement from occurring at these joints. construction joints should not be confused with expansion joints. expansion joints are usually used to allow for free movement of parts of a structure and which are normally designed for complete separation. construction joints are nearly always the weakest points in a structure. the main problem that remains therefore in the formation of a good construction joint is the capability of providing a well bonded medium between the hardened and the fresh concrete . thus construction joints in concrete structure should be placed where shear forces are expected to be low. both the location and the size of joint should in general be chosen according to the type of structure to ensure good performance of the structure and to provide acceptable appearance. in the case of reinforced concrete beams, construction joints may run horizontally, vertically, inclined or key joints; depending on the placing sequence prescribed by the design of the beam, fig.(1). the main concern in joint construction is in providing adequate shear transfer and flexural continuity through the joint. flexural continuity is achieved by continuing the reinforcement through the joint, while shear transverse is provided by shear friction between old and new concrete, and dowel action in reinforcement through the joint. construction joints may result in less than100 ℅ of shear capacity. the construction joints should be made in the following manner (3,4) : 1the surface of hardened concrete along the joint should be thoroughly roughened. 2the surface of the concrete should then be cleaned thoroughly to remove all foreign and attached matter such as waste. 3hardened concrete should be moistened thoroughly before new concrete is placed on it. 4no pool of water should be left standing on the wetted surface when new concrete is placed. fig. 1. types of construction joints. h h h h l l l l horizontal construction joint vertical construction joint key construction joint inclined construction joint zena waleed abas al-khwarizmi engineering journal, vol. 8, no. 1, pp 4864 (2012) 50 1.2. location of construction joint location of construction joints is usually predetermined by agreement between the architectural engineer and the contractor, so as to limit the work that can be done at one time to a convenient size, with the least impairment of the strength of the finished structure. generally, it is impractical to place concrete in lifts higher than one story. designer should recognize this when locating horizontal construction joints. for building in which the concrete walls are to be exposed, joints may be located at bends of ornamentation, ledge, rustications, or other architectural details. it is convenient to locate horizontal joints at the floor line in line with window sills. in the design of hydraulic structures, construction joints usually are spaced at shorter intervals than in non-hydraulic structures to reduce shrinkage and temperature stresses. construction joints should be located by the designer to provide logical separation between segments of the structure. as a rule, construction joints are allowed only where shown on the drawings. if the placing of concrete is involuntarily stopped for a time longer than the initial setting time of the concrete used, the old surface is to be considered as a construction joint, and treated as such before casting is resumed. the appearance of a structure can be influenced by the location of the construction joint, and the aim should be to install them in apposition that renders them as inconspicuous as possible; the alternative is to make them clearly visible as a feature of the structure. the joint should fit into the architectural design, and their location should facilitate the construction of forms and placing of concrete. however, from a point of view of strength of the structure, it is desirable to position construction joint at point of minimum shear. for slabs and beams it is, therefore, usual to have construction joint at mid span or in the middle third of the span. these rules are based on the assumption that a construction joint may result in less than 100% of shear capacity in the interface. if there were practicable to have such joints at the supports for slabs and beams, it improves appearance and result in a considerable saving in the cost of the formwork (5) . 2. variables of the test program the variables affecting the location of construction joints of reinforced concrete structure elements are studied experimentally. these variables include the location and type of the construction joint and whether or not stirrups are present at the joint. a. location of construction joint the effect of location of the joint is the main variable in this study. two different locations are considered: at the middle of the beam specimen and at the third point as shown in fig.( 2 ). the reason for choosing the two locations is to investigate the behavior of the reinforced concrete beams when the construction joint is at zero shear and maximum moment and at the zone of small shear and small moment. fig. 2. location of construction joints. l l l/2 l/3 first pour first pour second pour second pour construction joint construction joint aconstruction joint at the middle of the specimen (v=0, m=mmax.) h h zena waleed abas al-khwarizmi engineering journal, vol. 8, no. 1, pp 4864 (2012) 51 b. types of construction joint three types of construction joints were investigated in this study: b.1. vertical construction joint this type of construction joint is made by using stop-board of wood placed vertically after casting the first part of the beam. the stop-board has to be scatted to all longitudinal reinforcement to extend from the old concrete to new one, as shown in fig. ( 3 ). b.2. inclined construction joints in this type of construction joints, the stop board is cut so that various inclinations of the construction joints can be maintained. three inclinations were used, 30˚, 45˚and 60˚ with the vertical axes, as shown in fig. (4). the reason for choosing these three inclinations is to investigate the effect of such inclinations on the performance of the beam. fig. 3. vertical construction joint. fig. 4. types of inclined construction joints. vertical construction joint l h first pour construction joint construction joint construction joint first pour first pour second pour second pour second pour h h h l l l a30 inclined construction joint with vertical axes b45 inclined construction joint with vertical axes c-60 inclined construction joint with vertical axes 45 0 30 0 60 0 zena waleed abas al-khwarizmi engineering journal, vol. 8, no. 1, pp 4864 (2012) 52 b.3. key construction joints the key is normally formed by fixing beveled edge strip of wood to a stop board. the stop-board has to be scatted to all reinforcement to extend from the old concrete to the new one. the details of key construction joints used in this investigation are shown in fig. (5). fig. 5. types of key construction joints . c. presence of stirrups at the construction joint one of the groups contains stirrups at the construction joint located at third point of the beam it is used to compare the efficiency of such joint with other groups having joint at third point of the beam but without stirrups at that joint, see table (1).(note that in key joint , (l) shape stirrups was used throughout the joint). table1, test parameters of beam specimens. series no. specimen no. location of the joint stirrups at joint types of construction joint reference beam 19 without construction joint series one 1 at the middle of the specimen without stirrups at the joint vertical 2 inclined by 300 3 inclined by 450 4 inclined by 600 5 key joint i 6 key joint ii series two 7 at the third point of the specimen without stirrups at the joint vertical 8 inclined by 300 9 inclined by 450 10 inclined by 600 11 key joint i 12 key joint ii series three 13 at the third point of the specimen having ø 10 mm stirrups at the joint vertical 14 inclined by 300 15 inclined by 450 16 inclined by 600 17 key joint i 18 key joint ii * note:the concrete compressive strength for all beam specimens was 20 mpa (using cylinder mold). first pour second pour second pour construction joint construction joint l l h akey construction joint type i bkey construction joint type π h zena waleed abas al-khwarizmi engineering journal, vol. 8, no. 1, pp 4864 (2012) 53 3. experimental work the experimental work includes 19 simply supported reinforced concrete beams with dimensions of ( 200x 200x950mm), as shown in fig. (6) and plate(1a,1b). the specimens were reinforced with four longitudinal bars ( 2-ø12 mm bars at bottom and 2-ø10 mm bars at top) , and (ø10mm ) closed stirrups located at 80mmc/c along the beam. table (2) shows the properties of the reinforcement bars used. in all mixes, the cement was ordinary portland cement, type i, which was manufactured by the united company cement factory/iraq. alukhaider natural sand of (4.75mm) maximum size was used as fine aggregate. while the coarse aggregate was crushed gravel with max size of (19mm).table (3) shows the quantities of concrete mix used in beam specimens. fig. 6. dimensions and reinforcement details of beam specimens. plate1: beam specimens before testing (a) and (b). p symm. l h a a sec. (a-a) 200 120 40 40 200 ø10@80mmc/c 2ø10top bars 2ø12bot. bars all dimensions are in (mm) 1b 1a zena waleed abas al-khwarizmi engineering journal, vol. 8, no. 1, pp 4864 (2012) 54 table 2, properties of reinforcement bars. bar size(mm) area ab in (mm 2 ) yield strength in (mpa) tensile strength in (mpa) 10 78.5 513 601 12 113 572 666 table 3, quantities of concrete mix. concrete compressive strength (mpa) w/c ratio cement content (kg/m3) aggregate content (kg/m3) sand content (kg/m3) 20 0.6 215 1057 641.5 two slandered cylinders 150x300mm were cast from each batch of concrete during the casting of the first part of the specimen . another two cylinders were cast with second part of the specimen for each casting operation. thus, four cylinders for each specimen were made. the cylinders stored and cured under the same condition as the beam specimens and their compressive strength were measured at the time of testing . table (4) shows the concrete compressive strength for the beam specimens. table 4, actual concrete compressive strength for the beam specimens. series no. cylinder no. part 1 part 2 load (kn) compressive strength (mpa) load (kn) compressive strength (mpa) series one 1 342.8 19.4 349.9 19.8 2 355.2 20.1 335.7 19 average 19.7 average 19.4 series two 1 332.2 18.8 326.9 18.5 2 339.3 19.2 335.7 19 average 19 average 18.7 series three 1 351.6 19.9 342.8 19.4 2 360.5 20.4 346.6 19.6 average 20.2 average 19.5 the beam specimens with a construction joint were manufactured by casting one part of the specimen in an oiled plywood forms, and after 7 days the second part was cast to make the beam specimen as a one unit with construction joint between them. no attempt was made to improve the bond at the joint by degreasing or roughening the old face of concrete. electrical vibrator was used to vibrate the specimens. vibration process continued for 60 sec. the test specimens were removed from the mould after10 days. all the specimens were cured for 14 days by sprinkling. each specimen was loaded to failure in 1000 kn computer controlled verstile electronic test machine. the beam specimen is seated on the bending testing table for the machine. the concentrated load was applied at the center of the specimen gradually and the deformation was measured with 0.01 mm dial gauges located at the center of specimen, and at the construction joint when its location is at third point of the specimen. the displacement was recorded by the dial gauge groups at each 10 kn of load until failure occur either by cracking through the construction joint or through the concrete. zena waleed abas al-khwarizmi engineering journal, vol. 8, no. 1, pp 4864 (2012) 55 4. results, discussion and conclusions the load deflection curves for beams having construction joints are compared with load deflection curves for beams without construction joints , as shown in fig.(7) to fig.(24). deflections at center and / or at location of the construction joint are listed in table (5). fig. 9. load deflection behavior of beam no. (3) (series one). fig. 10. load deflection behavior of beam no. (4) (series one). without const. joint vertical const. joint at middle fig. 7. load deflection behavior of beam no. (1) (series one). fig. 8 load deflection behavior of beam no. (2) (series one). without const. joint 30 degree inclined const. joint at middle without const. joint 45 degree inclined const. joint at middle without const. joint 60 degree inclined const.joint at middle zena waleed abas al-khwarizmi engineering journal, vol. 8, no. 1, pp 4864 (2012) 56 fig. 13. load deflection behavior of beam no. (7) (series two). fig. 14. load deflection behavior of beam no. (8) (series two). fig.11. load deflection behavior of beam no. (5) (series one). fig.12. load deflection behavior of beam no. (6) (series one). without const. joint key const. joint type 1 at middle without const. joint key const. joint type 2 at middle without constjoint vertical const. joint at third point without constjoint 30 degree inclined const. joint at third point zena waleed abas al-khwarizmi engineering journal, vol. 8, no. 1, pp 4864 (2012) 57 fig. 17. load deflection behavior of beam no. (11) (series two). fig. 18. load deflection behavior of beam no. (12) (series two). fig.15. load deflection behavior of beam no. (9) (series two). fig.16. load deflection behavior of beam no. (10) (series two). without constjoint 45 degree inclined const. joint at third point without constjoint 60 degree inclined const. joint at third point without constjoint key const. joint type 1 at third point without const joint key const. joint type 2 at third point zena waleed abas al-khwarizmi engineering journal, vol. 8, no. 1, pp 4864 (2012) 58 fig. 19. load deflection behavior of beam no. (13) (series three). fig. 20. load deflection behavior of beam no. (14) (series three). fig. 21. load deflection behavior of beam no. (15) (series three). fig. 22. load deflection behavior of beam no. (16) (series three). without const joint 45 degree inclined const. joint with stirrups at third point without const joint 60 degree inclined const. joint with stirrups at third point without const joint vertical construction joint with stirrups at third point without const joint 30 degree inclined cons.joint with stirrups at third point zena waleed abas al-khwarizmi engineering journal, vol. 8, no. 1, pp 4864 (2012) 59 table 5, load, type of failure and ultimate deflection of the tested beam specimens. series no. specimens no. type of failure ultimate deflection at center (mm) failure load (kn) reference beam 19 flexural failure 3.6 80 series one 1 flexural failure 3.7 80 2 flexural failure 4 80 3 joint failure 3.6 70 4 joint failure 3.6 70 5 flexural failure 3.7 80 6 flexural failure 3.9 80 series two 7 joint failure 3.2 70 8 joint failure 3.8 70 9 joint failure 2.5 60 10 joint failure 2.9 6 11 joint failure 3.2 70 12 joint failure 3.6 70 t series three 13 flexural failure 3.8 80 14 flexural failure 3.8 80 15 joint failure 3.5 70 16 joint failure 3.7 70 17 flexural failure 3.7 80 18 flexural failure 3.8 80 the load was applied to the beam specimens until failure occurred through the construction joints or flexural failure developed. close to failure, the flexural cracks change into inclined shear cracks pointing toward the compression zone. during tests, specimens were examined for cracks. the load at which each crack becomes visible was marked. the behavior of the reference beam (beam without construction joint) as shown in plate (2) and (3) is similar to ordinary reinforced concrete beams failing in flexure. the first crack develops at the beam center at stress which is close to flexural strength of concrete. as the load increased, several other flexural cracks on without const joint key construction joint type 1 with stirrups at third point without const joint key construction joint type2 with stirrups at third point fig. 23. load deflection behavior of beam no. (17) (series three). fig. 24. load deflection behavior of beam no. (18) (series three). zena waleed abas al-khwarizmi engineering journal, vol. 8, no. 1, pp 4864 (2012) 60 both sides of the central region developed. near failure which occurs at about 80 kn, these flexural cracks change direction toward the load location. the measured ultimate deflection was 3.6 mm. plate (2) testing machine. plate (3) beam without construction joint (reference beam) after testing . for beam specimens with construction joint at middle section of the specimens (series one) the primary type of failure depends on the type of construction joint. the joint failure (crack through the joint) occurs when the construction joint is inclined at an angle greater than or equal 45° with vertical axis, as shown in plate (4). flexural crack failure similar to the failure of the reference beam was observed to occur when the inclination angle is less than 45° with vertical axis. the primary type of failure for series two (specimens with construction joints at third point) was by cracking through the construction joint (joint failure). no cracks outside the joint location were observed in these specimens during the test. the load-deflection curves indicate that the deflection at all load levels is greater than the deflection of the reference beam. for series three it is obvious that the presence of stirrups at the construction joints improves the performance of these beams relative to similar beams with construction joints but without stirrups. plate(4) beam with 60° inclined construction joint at midspan after testing. the beams with stirrups at the construction joint failed by flexural cracking at higher load level when compared with beam specimens with construction joints but without stirrups at these joints . specimens with construction joints at third point failed by cracking through the joints as shown in plate (5) at lower load levels of comparable specimens with construction joint at middle of the beam specimens . as shown in table (5), and figs. ( 25 ) and ( 26 ). zena waleed abas al-khwarizmi engineering journal, vol. 8, no. 1, pp 4864 (2012) 61 plate (5) beam with vertical construction joint at third point without stirrups after testing . fig. 25. effect of location of vertical construction joint. fig. 26.effect of location of 45 0 inclined construction joint. the reason for failure through the construction joints located at third points may be explained on the basis of presence of greater tension in concrete at these locations as compared to no tension at mid span. the presence of such tension reduces the shear capacity possibly because adhesion and friction at the interface between new and old concrete may be affected. for beams and slabs it is usual to have construction joints at mid span or in the middle third of the span. these rules are based on the assumption that a construction joint may result in less than 100% of shear capacity at the interface. the type of construction joints was found to be an important factor affecting the behavior of the tested beams. the vertical and key construction joints have similar performance and the capacity and deflection of these beams are close to that of the reference beam. the effect of inclined construction joints depends primarily on the degree of inclination of the surface of concrete; lower inclination with vertical axis gives higher strength joints. as shown in table (5) and figs. (27) and (28). fig. 27. effect of type of construction joint at middle. 0 10 20 30 40 50 60 70 80 90 0 1 2 3 4 vertical const. joint at middle vertical construction joint at third point deflection(mm) 0 10 20 30 40 50 60 70 80 0 1 2 3 4 lo ad (k n ) deflection (mm) 45 degree inclined const. joint at middle 45 degree inclined const. joint at third point l o a d ( k n ) 0 10 20 30 40 50 60 70 80 90 0 2 4 lo ad (k n ) deflection (mm) vertical const. joint at middle 45 degree inclined const. joint at middle key const. joint type 1 at middle zena waleed abas al-khwarizmi engineering journal, vol. 8, no. 1, pp 4864 (2012) 62 fig. 28. effect of type of construction joint at third point . when stirrups were added at the construction joints, the strength of beams increases with the increase in percentage of steel across the construction joint . the behavior of these beam specimens during tests was similar to the behavior of beam specimens of series one where the construction joints at midspan. table (5) shows that these specimens fail at higher levels of loads when compared with beam specimens with construction joints at third point without stirrups. table (5) shows that the type of failure of vertical, 45° inclined construction joint and less with vertical axis, and key construction joints for series three specimens failed by flexural failure which is different from the type of failure of beam specimens of series two which failed by joint failure. it can be concluded that the presence of stirrups at the construction joint have improved the behavior of beam specimens. figs. (29 ) and (30 ) shows the effect of the presence of stirrups at the construction joints with similar beams having no stirrups at the construction joints. 0 10 20 30 40 50 60 70 80 0 1 2 3 4 lo ad (k n ) deflection (mm) vertical construction joint at third point 45 degree inclined construction joint at third point key construction joint at third point fig. 29. effect of presence of stirrups at vertical construction joint . fig. 30. effect of presence of stirrups at 45 0 inclined construction joint . 0 10 20 30 40 50 60 70 80 90 0 2 4 lo ad (k n ) deflection (mm) vertical const. joint at third point without stirrups vertical construction joint at third point with stirrups 0 10 20 30 40 50 60 70 80 0 2 4 lo a d ( k n ) deflection (mm) 45 degree inclined const. joint at third point without stirrups 45 degree inclined construction joint at third point with stirrups zena waleed abas al-khwarizmi engineering journal, vol. 8, no. 1, pp 4864 (2012) 63 from the experimental results the following conclusions can be drawn: 1it is preferable to locate the construction joint at the point of zero shear perpendicular to the main reinforcement. in this investigation it is found that beams with construction joints at zero shears perform better than beams with construction joint at the third points of specimens (the percentage of reduction in ultimate load capacity is in range of 2% -15%). 2vertical construction joints have a slight effect on the overall behavior of reinforced concrete beams under flexural mode when they are placed at the middle of the beam span (zero shears). the load carrying capacity for the tested beam with vertical construction joints is about95% of the capacity of the reference beam without construction joint. 3the effects of inclined construction joints depend primarily on the degree of inclination of the surface of concrete, lower inclination with vertical axis gives higher strength joints. the load carrying capacity of beam with construction joints inclined by 45° is in the range between(8%20%) lower than that of beam without construction joint. 4the percentage of steel across the joint (i.e. amount of stirrups at the construction joints) affects the overall load-deflection behavior of reinforced concrete beams having construction joint. as the amount of such steel is increased, the ultimate load-carrying capacity increased. for the studied cases, it is found that increasing the amount of steel across the joint in the range of (50%100%) causes an increase in capacity in the range of (7%15%) and a decrease in the ultimate deflection in the range of (20%48%). 5the performance of beam with vertical or key construction joints is similar to the performance of beams without construction joints. 5. refrences [1] aci committee report 224.3r-95 "joints in concrete construction", pp. 1-44, 1995. [2] p. critchell, "joints and cracks in concrete", cr books (a maclaren company), london, 1968. [3] m. fintel, "joints in buildings", handbook of concrete engineering, 2nd edition, pp.121, 1985 [4] a. mattock, "cyclic shear transfer and type of interface", journal of the structural division, asce, vol.107, no. st10, pp.599616, 1987. [5] c. desai and m. zaman, "thin-layer element for interface and joints", international journal for numerical and analytical method in geometrical, vol.8, pp.19-43, 1984. 48-64 (2012) صفحة ،1 ،العذد8 مجلة الخىارزمي الهنذسية المجلذ زينة وليذ عباس 64 تاثير المفصل االنشائي على تصرف العتبات الكىنكريتية المسلحة زينة وليذ عباس انجامعت انمسخىصشٔت/ لسم انٍىذست انمذوٕت الخالصة إن انمفاصم اإلوشائٕت ٌٓ عباسة عه مىاطك انخُلف فٓ عمهٕت صب انخشساوت َ ٌٓ ضشَسٔت فٓ عذٔذ مه انمىشاث انخٓ ال ٔمكه فٍٕا صب انخشساوت انمفصم . إن ممذاس انخشساوت انخٓ ٔمكه صبٍا ٔعخمذ عهّ انسعت اإلوخاجٕت َ سعت انخهظ فٓ انمُالع َ عهّ وُعٕت انمُانب انمسخخذمت. عهّ مشدهت َادذة فٓ ٌزا انبذث حم دساست حأثٕش أوُاع َ مُالع انمفاصم اإلوشائٕت عهّ أداء األجضاء . اإلوشائٓ انجٕذ ُٔفش اسخمشاسٔت نهمص َ االوذىاء خالل انسطخ انبٕىٓ .انخشساوٕت عه طشٔك فذص ومارج عمهٕا فٓ انمخخبش ، وُع (فٓ مىخصف أَ ثهث انىمُرج)إن انمخغٕشاث انخٓ حم اعخمادٌا ٌٓ مُلع انمفصم اإلوشائٓ . (مهم)950*200*200 ومُرج باألبعاد 19حم فذص حم فذص انىمارج بُاسطت ماكىت فذص . ، َ إضافت أطُاق فٓ انمفصم اإلوشائٓ(عمُدْ، مائم بضأَت مع انمذُس انعمُدْ ، لفم َ مفخاح)انمفصم اإلوشائٓ حشٕش انىخائج انعمهٕت إنّ . َضعج انىمارج بشكم ٔسمخ بمٕاط ممذاس االوذشاف فٓ مىخصف أَ حذج انمفصم نكم مشدهت دمم. وُٕحه كٕهُ 1000راث سعت وسبت ) َ حشٕش أٔضا إنّ إن انمفصم انعمُدْ رَ حأثٕش بسٕظ عهّ لُة انىمارج ،إن أفضم مُلع نهمفصم اإلوشائٓ ٌُ فٓ انمىاطك انخٓ فٍٕا لُِ لص لهٕهت َ نكه ، ُٔجذ ومصان را حأثٕش مهذُظ عهّ لُة انىمارج مع صٔادة دسجت مٕم انمفصم اإلوشائٓ مع انمذُس انعمُدْ (%5% -صفش )االوخفاض جاءث بٕه ََجذ فٓ ٌزي انذساست أٔضا إن إضافت دذٔذ انخسهٕخ عهّ شكم أطُاق فٓ مىطمت انمفصم اإلوشائٓ مخغٕش مٍم نً . (%20%-8)وسبت االوخفاض كاوج بٕه حأثٕش عهّ وُع انفشم انذاصم َ مماَمت انخذمم انمصُِ ، ََجذ إن صٔادة كمٕت انذذٔذ فٓ مىطمت انمفصم ٔؤدْ إنّ صٔادة فٓ مماَمت انخذمم انىٍائٕت ما بٕه % ( . 48%-20)فٓ ممذاس االوذشاف ما بٕه َ ومصان (%15%-7) a <4d6963726f736f667420576f7264202d20dfd1ede320e6dac7cfe120d4c8edc820e6e3d5d8ddec33392d3531> 1 al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 14, no. 1, march, (2018) p.p. 39-51 experimental evaluation and finite element simulation to produce square cup by deep drawing process karem muhsin younis* adil shbeeb jabber ** mustafa mohammed abdulrazaq *** *, **,*** department of production engineering and metallurgy engineering/ university of technology *email: kamarabbas 89@yahoo.com **email: adilshbeeb@yahoo.com ***email: mustafaalneame@yahoo.com (received 8 march 2017; accepted 17 october 2017) https://doi.org/10.22153/kej.2018.10.002 abstract deep drawing process to produce square cup is very complex process due to a lot of process parameters which control on this process, therefore associated with it many of defects such as earing, wrinkling and fracture. study of the effect of some process parameters to determine the values of these parameters which give the best result, the distributions for the thickness and depths of the cup were used to estimate the effect of the parameters on the cup numerically, in addition to experimental verification just to the conditions which give the best numerical predictions in order to reduce the time, efforts and costs for producing square cup with less defects experimentally is the aim of this study. the numerical analysis is used to study the effect of some parameters such as die profile radius, radial clearance between die and punch, blank diameter on the length and thickness distributions on the cup, dynamic-explicit (ansys11) code based on finite element method is utilized to simulate the square deep drawing operation. experiments were done for comparison and verification the numerical predictions. effective square cup with less defects and acceptable thickness distributions were produced in this study. it is concluded the most thinning appear in the corner cup due to excessive stretching occur in this region and also it is found the cup thickness and height prediction by numerical analysis and in general in harmony with experimental analysis. keywords: square deep drawing, finite element method, thickness distribution. 1. introduction sheet metal forming is one of the most widely used manufacturing processes for the fabrication with a wide range of products in various industries. cylindrical, rectangular and some complex shaped parts can be produced with the help of process [1]. deep drawing process is one of the important sheet metal forming processes, traditional deep drawing is a process by which a sheet of metal with certain thickness is converted to certain shape of geometry, the blank (undeformed sheet), is placed onto the die which have cavity, and it is pressed by punch into the die cavity, the schematic illustration of the deep drawing process and variables of it shown in the figure (1). deep drawing of square cup is one of the most widely utilized operations in sheet metal forming technology, it has been widely used for hundreds of years. karem muhsin younis al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 3951 (2018) 40 fig. 1. (a) schematic illustration of the deep drawing process, (b) variables in deep drawing process[2]. for example, it is utilized to produce car parts in automotive manufacture, utilized in electrical power engineering and aerospace industries, also making domestic items like kitchen sinks, square shaped parts are very critical in deep drawing process as stresses induced are not same in all directions. various factors affect this process like blank size, blank thickness, die fillet radius, punch profile radius, lubrication [1,3,4]. therefore modern researches focus on the optimum values of these process parameters for non-symmetrical deep drawing parts ( square, rectangular, triangular and hexagonal shapes), in the field of square deep drawing process more researches have been focused. e. onder, a.e. tekkaya [5] reported that numerical analysis of different blank shape using various sheet metal forming processes such as conventional deep drawing, hydro-mechanical deep drawing and high pressure sheet metal process, the effect of some process parameters were studied for each cross section, two types of steel have been used as materials blank in the numerical analysis and on the experimental verification. dynamic-explicit fe software and an elastic-plastic model was used in this numerical analysis. the analysis displayed that depending on the blank shape and dimensional setup certain process are preferable for obtaining more satisfactory products. it is concluded from this study the hydro-mechanical deep drawing can produce cup with less thinning while the high pressure sheet metal yields the largest thinning in the product with same geometry. common conclusions derived out from the research carried out by halil uibranhim demirci, cemal esner and mustafa yaser [6] to investigate the effect of the blank holder force on wall thickness, cup depths, tearing and wrinkling in square deep drawing process experimentally and numerically via the ls-dyna software are summarized as follows: the wall thickness distributions obtained by experimental and finite element method is seem to be showing generally errors of around 15%, it is observed that thickness of the cup wall gets thinner in the punch profile region and increased in thickness occur toward the edges of the cup section. k. youns, m. j. abdrasul [7] study the effect of die and punch corner radii on the behavior and flow of metal and at the limit of fracture (failure is of any breaks in the square cup) in the process of deep drawing and compare the practical results with the theoretical results that we get by using the method of finite element analysis, the fem code the commercially available software (ansys 113d) used here. moshen et al [8] have proposed a newly process to raise the formability for the square deep drawing process by using flat headed square punch to deformed the flat circular blank in to conical shaped die with square orifice at its end. fea was utilized to investigate the effect of geometrical parameter such as die and punch profile radius, punch and die corner radius, die cone angle, relative clearance and initial thickness of the blank on the square cup formability in order that determine the optimal values of these parameters, the limit drawing ratios were utilized karem muhsin younis al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 3951 (2018) 41 to estimate the impact of the parameters on the drawability of cup. experiments with same conditions have been done to verify the fe predications. it is concluded the ldr obtained from this process is significant higher than that of the improved classical deep drawing ways. u. pranavi et al evaluated the formability of aa 6061 aluminum alloy blank with thickness of 2mm by using deep drawing process to produce square cups, numerical simulation commercial fem code in which hollomom's power law and hill's 1948 yield criterions are implemental to investigate the influence of blank holder force, punch and die profile radius, lubricating conditions and blank size [9]. the deep drawing of a rectangular cup from aisi 304 stainless steel sheet was investigated numerically and experimentally. the fem was used for computer modeling of the deep-drawing process. the thickness distribution predicted from the fea was compared with experimental measurements. it was observed that the numerical results agree well with the experimental values. the minimum thickness was observed at the punch radius in both the simulation and experiment were studied by b. sener, h. kurtaran [10]. h. vairavan, a.b. abdullah [11] study the mode of thinning in the square deep drawing process by focusing on the alignment between punch and die. the thickness measurements of the square cup are obtained by analyzing the images obtained from the alicona infinite system, a commercial 3d non-contact surface measurement system. the reduction in the thickness mode is then mapped on the basis of the measurements made on a few positions along the drawn blank cross-sectional profile. it concluded that misalignments increase the load required for the drawing process, therefore this high load will increasing the probability of occurs fracture in the square cup especially in the corner region. furthermore, misalignments also may cause non uniform distribution thickness, thus leading to the early failure of the blank. modeling and the corresponding experimental validation of angular deep drawing parameters on the thickness of the wall, tensile strength and height of the square profile cups. the full factorial experimental method was used to collect the data. the results of finite element analysis were compared with measurements of experimental. as a consequence, it was showed that angular deep drawing dies gave best results with different angle values than conventional dies with higher drawing ratios. in general, the quality of the cup increased by an increase of the die/blank holder angle. finite element method model results were in good agreement with experimental measurements [12]. consequently, the present work focused on the main object is the avoiding the fracture and excessive wrinkling may occur in the square deep drawing process to achieve this objective must study the square deep drawing process and the parameters required for defect free finished part that requires a lot of trials to achieve this goal experimentally. therefore, studied the effect of the some process parameters ( die profile radius, blank size and clearance) on the thickness distributions throughout the cup and lengths of the cups and then determine the optimum values of these parameters numerically by using ansys software to reduce the efforts, time and costs, finally the experimental verification can be done only for optimum values of the process parameters obtained from the numerical results. 2. experimental procedures 2.1 material selection the properties of material to be drawn by square deep drawing have significant influence on the success of this drawing operation. low carbon steel (1008-aisi) was used in this study. this material is selected because of its good formability, specification and widespread usage in the industry, with sheet thickness 0.7mm to reduce the possibility of wrinkles defects based on the results extracted from previous researches. chemical composition test was carried out by using spectrometer device to verify the manufacturing certificate of (1008-aisi) low carbon steel. the composition studied in the state company for inspection and engineering rehabilitation activities (s.i.e.r) as shown in table (1). table 1, the chemical composition of the low carbon steel (1008aisi). element c% mn% si % p% s% measured 0.08 0.32 0.02 0.015 0.021 aisi =<0.1 0.3-0.5 0.01 =<0.04 =<0.05 element cr% cu% al % mo% ni% measured 0.03 0.09 0.05 0.002 0.03 aisi 2.2 material properties to find out the mechanical properties of the sheet blank to be drawn, tensile test carried out for karem muhsin younis al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 3951 (2018) 42 this purpose. firstly specimens were cut from the sheet and tested according to astm (american society for testing of materials) standard e8m specification, the dimensions of tensile specimen as shown in figure (1), then the specimens were fixed carefully by the gripper on the universal testing machine type (wdw-200e), after that it loaded until fracture occurred under cross head speed 2mm/min at strain rate 6.6χ10-4 s-1. the tensile test has been done in the university of technology-production engineering and metallurgy, strength of material laboratory, the universal testing machine used in this study as shown in figure (2). fig. 1. the dimensions of the tensile test specimen according to astm standard e8m specification. fig. 2. the tensile test machine type (wdw-200e). the tensile test machine directly gives the curves between load-deformation curve and engineering stress-engineering strain curve, and by using the equation (1) and (2) below can get the data for drawing the true stresstrue strain curve . the relationship between true stress and true strain curve was described in figure (3). fig. 3. true stress and true strain curve. the true stress-strain curve was concluded from engineering stress-strain curve that obtained directly from testing machine. the slope of linear elastic region define the modulus of elasticity while the slope of the flow curve at specific level of stress (yield stress) is tangent modulus, the yield stress was evaluated by taking the 0.2% offset from this curve, and determined the strength coefficient and strain hardening exponent by taking the logarithm true stress and true strain for data in the uniform plastic deformation region where the strain hardening exponent is the slope of the logarithmic curve and strength coefficient is the value of intersection this logarithmic curve with stress at true strain equal to 0.1. the mechanical properties for low carbon steel blank as shown in table (2). three tensile specimens were tested in order to take the average values to reduce the errors obtain from measurements. � � �° �1 � � …(1) ∈ � ln ��°� …(2) karem muhsin younis al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 3951 (2018) 43 where � = true stress, �° = engineering stress, ∈ = true strain, e = engineering strain, � �° = ratio between instantaneous length and original length of the gauge section of the tension test specimen. table 2, the mechanical properties of the sheet used. property symbol value unit young modulus e 200 gpa poisson ratio ʋ 0.3 (from the standard tables) mm/mm offset yield stress �y 203 mpa tangent modulus et 0.5 gpa strain hardening exponent n 0.23 -- strength coefficient k 548 mpa 3. numerical simulation 3.1 modeling commercial finite element analysis code ansys11.0 was utilized to model and analysis the deep drawing operation, in which the nonlinear issues are solved by using "implicit method "newton-raphson. in this method, the stroke of the punch is defined with steps throughout the forming process over the certain time range to adjust the velocity of the punch. solutions (time steps or sub steps) are carried out in order to apply the movement on the punch gradually in each step. at each substep, a number of equilibrium iterations are carried out to get a converged solution. because the geometry of tool and sheet are longitudinal and lateral axial symmetry and also symmetry in the constraints and boundary conditions, the only a one fourth section of the model needed was analyzed. the fe model of the sheet material, drawing die and sequence of deformation mechanism throughout the square deep drawing process is shown in figure (4). b a c karem muhsin younis al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 3951 (2018) 44 fig. 4. a) finite element model of tools, b-f) sequence of the deep drawing deformation of the blank. bilinear isotropic hardening option uses the von mises yield criterion connected with an isotropic work hardening assumption. the principal axes of anisotropy coincide with the material (or element) coordinate system. elastoplastic constitutive model with isotropic strain hardening was utilized to simulate the sheet response. the elastic behavior was taken to be linear and the plastic response was modeled using hill's 1948 yield criterion (anisotropic). for simplifying the simulation of the deep drawing processes, the following assumptions were made: 1 the deformations in the tool are very small when compare it with the deformations in the sheet, therefore the dies were rigid assumed to reduction the solution time with acceptable accuracy. 2the punch moved down at constant velocity (60mm/min) throughout the deep drawing process and the die was fix. 3no change in the temperature during the forming process, no heat transfers between tool and sheet. 3.2 element type and meshing the 3-d 8-node structural solid element of solid45 was utilized for blank. the tool set (punch, die and blank holder) were modeled as rigid bodies. element sizes are controlled by controlling the division specification of lines. mesh density of the blank and tools affect the accuracy of the results. so the meshes in the blank are finer than the meshes in the tool in order to get the accurate results for large deformations which occurs in the blank. the most significant regions of the tool whose mesh density affects the accuracy and reliability of the results are its entry radius of the die and punch, the meshes of these regions are finer than other portions. the pilot node was used to define the motion of the punch; the pilot node was used to gain the drawing force during the simulation. the pilot node has degrees of freedom which represent the motion of the entire rigid surface, including three translational and three rotational degrees of freedom in three dimensions, and two translational and one rotational degrees of freedom in two dimensions, and the boundary conditions (displacement), concentrated loads, rotations can be applied to the pilot node. f e d karem muhsin younis al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 3951 (2018) 45 3.3. contact automatic contact procedures in ansys11.0 were utilized to model the complex interaction between the tooling and sheet. for flexible (blank) and rigid (tool set) contact, target elements of targe170 were utilized, to act three dimensions target (punch, die, blank holder) surfaces which were associated with the deformable body (sheet) acted by three dimensions 8-node contact elements of conta174. the target and contact surfaces constitute a "contact pair", which were utilized to represent contact and sliding between the surfaces of blank and tool set. a coulomb friction law was used to study the influence of friction at the materials and tool interface, the constant friction is assumed at the drawing sheet and tool interface. 4. deep drawing test experimental equipment were design and implemented to produce square cup, they are made from tool steel which were machined by wire cut machine and polished in order to obtain good surface finish, the operations of the manufacturing of equipments of deep drawing process were done in local market. these equipment were setup on the universal tensile machine, the specification of this tensile machine used to produce square cup by deep drawing process as shown in table (3).the parameters of experimental tooling is described in table (4). circular blank with diameter of 80 mm and thickness of 0.7mm putted on the die surface and punch will drop toward the die in order to deform the blank. drawing speed used equal to 60 mm/min, the blank holder force was determined as the minimum value which prevent wrinkling by trial and error; it was 15kn-18kn. the deep drawing test has been done in the university of technology-production engineering and metallurgy, strength of material laboratory, schematic representation of rig deep drawing tooling as shown in figure (5), the tools of the deep drawing process and the universal testing machine used in this study as shown in figure (6). table 3, main specification of the universal testing machine used in the deep drawing process. aspects specification model wdw-200e capacity 200kn range of speed (0-500) mm/min possibility of testing tensile, compression, bending standard follow iso 68921:2009 (e) table 4, parameters process of square deep drawing. parameter symbol value unit length of square punch lp 40 mm punch profile radius rp 5 mm punch corner radius rc 5 mm length of square die ld 41.55 mm die fillet radius rd 5 mm clearance c 0.77 mm in order to study the strain distribution within the cup during drawing process, a grid pattern of ( 5, 10, 15, 20, 25, 30, ….mm) radius circles was printed on undeformed blank by using mechanical grid marker (compasses), after deformation the change in the grid circles will occurs. circular blank were drawn with different sizes to study the effect of some parameters on the length and thickness distribution in the square cup drawn. 1 2 3 4 5 6 7 top plate guide spring punch plank holder die bottom plate fig. 5. schematic representation of rig deep drawing tooling. karem muhsin younis al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 3951 (2018) 46 fig. 6. the tools of deep drawing process. 5. results and discussion the result can be divided into three sections. first section covers the effect some parameters on the height of the square cup drawn by fem, second section describes results of thickness distributions on the cup from center to the edge of cup in the rolling direction by fem, and final section deals with comparison between experimental and numerical results to valid the numerical result. 5.1 cup heights there are a lot of parameters effect on the square deep drawing process in order to produce product with acceptable defects, it must be study the effect of these parameters on the cup drawn. in this section effect of some parameters such as radial clearance and blank size on the height of the square cup are studied, as well as there are flat and corner sides in the square die cavity lead to different metal flow along the square die cavity, thus the process will be most difficult in this research. the numerical analysis were performed using ansys 11 commercial finite element code. mild steel materials have the tool geometry with (punch and die profile radius in mm) [rp=5, rd=5], (blank diameter in mm) d=80, (blank holder force in kn) bhf=15, value of coefficient of friction µ=0.1, (punch speed in mm/min) v=60, and then the numerical results were compared with the experimental. the circular blank was placed onto the die with taking into consideration rolling direction of the sheet. figure (6) represents the effect of radial clearance on the cup height, four value of clearance are used with constant remaining parameters. it is noted that from the figure, the cup height increases with decreasing the radial clearance and reaches the maximum height at corner of the cup. it can be concluded that when the radial clearance (gap between punch and die) is less than or equal to the thickness of blank, accumulation of metal in some flange regions is obtained by compression stresses, this metal in this region will flow into die cavity and because it has thickness more than the gap between die and punch, it cannot flow into die cavity causing stretching deformation. consequently, the height of the cup is increased. sample with clearance equal to the thickness of sheet metal for example, it is noted the length of the cup in the flat side equal to 24.6 mm but it reach to the 28.8mm in the corner region due to excessive stretching occur in this region and then return deceases to the 24.9mm in the perpendicular direction on the rolling direction. figures (7) show the effect of the blank size on the cup height in the square deep drawing. circular blanks with diameters (d=78, 80, 82, 84, and 86mm), and thickness of 0.7mm for all blanks used with keep constant remaining parameters. as expected the cup height increases as the blank size increases due to increase in the amount of metal sheet used to produce cup. the average length of the cup is 23mm when use blank diameter 78mm but the average length of cup reach to 31mm when use blank diameter 86mm. fig. 6. the effect of radial clearance on the cup height. karem muhsin younis al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 3951 (2018) 47 fig. 7. the effect of blank size on cup height. 5.2 cup thickness this research shows the variations in the die profile radius have a great influence on the predicted thinning distribution on the cup drawn by deep drawing process. four types of the die profile radius (3, 5, 6, and 7 mm), with punch profile radius (5 mm), (blank diameter in mm) d=80, (blank holder force in kn) bhf=15, (coefficient of friction) µ=0.1, (punch speed in mm/min) v=60 were chosen. figure (8) shows the effect of die profile radius on cup wall thickness along 0º with respect to rolling direction. it is obvious that the thickening increases with increasing die corner radius because the amount of stretching will reduce on the large profile radius, when in the smallest die profile radius the more thinning displayed in the cup drawing due to excessive bending and unbending occurs in small radius. in is noted more thinning occur in the punch profile region when use rd=3, the percentage of thinning reached to 5% while the maximum thickening occur in the cup edge when use rd=7, the percentage of thickening reached to 8%. these percentages are acceptable. fig. 8. the effect of die profile radius on the cup wall thickness along rolling direction. figure (9) presentations the influence of blank size on the cup wall thickness distribution in the direction of the rolling. it is evident that the thickness remains constant under the punch face (cup bottom) for all blank sizes ( no deformation occurs in this region), and decreases with increasing the blank size at the punch corner region, the more thinning occurs because of stretching in the punch profile region and then begins to rise until reaching maximum value at the cup rim with increasing the blank size. it is obvious from the figure the thickness of the cup in the base region for all blank sizes used is equal to the initial thickness of the blank 0.7mm, while in the punch profile region the thickness decreased to the 0.65mm for all sizes ob blank used and then increased to reach maximum value of thickness at the rim of the cup 0.77mm. fig. 9. the effect of blank size on the cup wall thickness along rolling direction. karem muhsin younis al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 3951 (2018) 48 5.3. comparison between numerical and experimental result the fea was performed to investigate the effects of the process parameters on the square cup drawing. in order to validate the finite element simulation results, the actual square cup drawings for mild steel materials have tool geometry [rp=5, rd=5] (punch and die profile radius mm), in different blank sizes were conducted and the experimental results were compared with the fe simulation results. in order to measure the cup wall thickness, the drawn cup was divided into two parts by using a diamond saw as shown in figure (10). heights of cups can be measured by using simple devices such as vernier caliper or ruler as shown in figure (11). fig. 10. the sample of divided cup. fig. 11. the sample of cup. figure (12) represents the cup height for different blank sizes theoretically and experimentally, it is noted from the figure there are low difference between lengths measured experimentally and numerically reached to 7% and this percentage of difference is acceptable value. figure (13) represents the thickness distribution along 0º with respect to rolling direction. it is evident from the figures that the predicted values and calculated values have the same trends, but they are different in values, the value of difference between them reached to 3%. this give indicator the numerical method used a powerful tool to simulate the sheet metal process to reduce the cost, time and effort. the difference between the fe and experimental results can be accounted for by possible errors in both analyses and experimental. in analyses the possible errors are due to the lack in the exact information about material properties and friction condition, in experimental the possible errors are due to the blank thickness variation, also due to the misalignment of the blank over the ring die. the errors in measurement of the forming loads result from fluid pressure losses in the hydraulic systems. fig. 12. the heights of the cup versus angle in degree from rd, a) fem and b)experimentally. karem muhsin younis al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 3951 (2018) 49 fig. 13. the distributions of the cup wall thickness experimentally and fem along rolling direction, a)fem, b)experimental. 6. conclusion the following are specific conclusions of the current research. 1. the deformation states vary along the square die cavity, the flow of metal at the corner of the cup is less uniform and more complex than that in the cup side walls. therefore square cup forming process experience very complicate. 2. the cup height is very affect by radial clearance between punch and die, decreasing in radial clearance will increasing the height of the cup. 3. increasing in blank size will increasing in the height of the cup. 4. most thinning appear in the corner cup due to excessive stretching occur in this region. 5. most thickening appear in the edge cup due to compressive stresses in this region. 6. increasing in die profile radius and blank size will reduce the thinning in the cup square cup drawn. 7. possible errors in both numerical analyses and experimental can be explained the difference between the fe and experimental results. 8. the earing in square cup depending on the planar anisotropy of sheet and difference in flow through the die cavity. 9. increased in the die profile radius increased to occur the wrinkling while decreased in the die profile radius increased the thinning in the cup. 7. references [1] pradipkumar n. patil, k.h. inamdar," a review on deep drawing of rectangular shaped parts ", asian journal of convergence in technology, volume ii, issue iii, issn no.:2350-1146, i.f-2.71,(2014). [2] j. s. colton," sheet metal forming", manufacturing processes and engineering, georgia institute of technology, version 1, 2009. [3] k. lange (ed.), handbook of metal forming, mcgraw-hill, new york, 1985. [4] f. ayari, t. lazghab, e. bayraktar," parametric finite element analysis of square deep drawing", archives of computational materials science and surface engineering, volume 1, issue 2, (2009). [5] erkan, o., erman tekkaya,. a." numerical simulation of various cross sectional workpieces using conventional deep drawing and hydroforming technologies", international journal of machine tools & manufacture 48, 532–542, 2008. [6] halil uibranhim demirci, cemal esner, mustafa yaser, " effect of the blank holder force on drawing of aluminum alloy square cup: theoretical and experimental analysis", jouneral of materials processing technology 206, 152-160, (2008). [7] karem. m. younis, makie. j. abd-rasul" effect of die and punch corner radii in the deep drawing on fracture of square cup ",m.sc thesis, department of production engineering and metallurgy, university of technological, (2013) . [8] mohsen hassan, labib hezam, mohamed elsebaie, judha purbolaksono, " deep drawing characteristics of square cups through conical dies ", procedia engineering 81 (2014 ) 873 – 880. [9] u pranavi, perumalla janaki ramulu, ch chandramouli, dasari govardhan, pvs.ram prasad, " formability analysis of aluminum alloys through deep drawing process", materials science and engineering, iop conf. series: materials science and engineering 149 (2016) 012025. karem muhsin younis al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 3951 (2018) 50 [10] b. sener, h. kurtaran," modeling the deep drawing of an aisi 304 stainless-steel rectangular cup using the finite element method and an experimental validation", materials and technology 50 (2016) 6, 961– 965. [11] h. vairavan, a.b. abdullah," die-punch alignment and its effect on the thinning pattern in the square-shaped deep drawing of aluminum alloy" international journal of materials and product technology 54(1/2/3):147 . january 2017. [12] e. ünal, c. özek, " a study on the wall thickness in the angular deep drawing process", materials testing, vol. 59, no. 2, pp. 178-182,2017. )2018( 39-51، صفحة 1د، العد14دجلة الخوارزمي الهندسية المجلم كريم محسن يونس 51 عملي و المحاكاة بالعناصر المحدد إلنتاج وعاء مربع بواسطة عملية السحب العميقبحث *** مصطفى محمد عبد الرزاق **عادل شبيب جابر كريم محسن يونس* الجامعة التكنولوجية /هندسة االنتاج والمعادن قسم*,**,** yahoo.comkamarabbas@89:*البريد االلكتروني adilshbeeb@yahoo.com **البريد االلكتروني: mustafaalneame@yahoo.com***البريد االلكتروني: خالصة لكثير من العيوب عملية السحب العميق المستخدمة إلنتاج أوعية المربعة الشكل هو عملية جدا معقدة وتسيطر عليه الكثير من المتغيرات وبالتالي ترافقها ا , حيث تم لتي تعطي أفضل النتائج ا المتغيرات هتحديد قيم هذالعملية ل المتغيرات بعض من هذهمثل التاذن والتجاعيد والكسر في األواني الناتجة. دراسة تأثير الظروف التي تعطي أفضل إلى اإلثبات التجريبيعدديا, إضافة لغرض دراسة تأثير هذا المتغيرات االعتماد على توزيع السمك واألعماق لوعاء المنتج هو هدف هذا البحث. دراسة عددية استخدمت لدراسة تجريبا وعاء مربع خالي من العيوب إلنتاج تقليل الجهود والوقت والكلفة لغرض فقط التنبؤات العددية عاء تأثير بعض المتغيرات من نص قطر تقوس القالب والخلوص بين القالب والخرامة و قطر الغفل على ارتفاع الوعاء و توزيع السمك على طول الو كاة لعملية السحب العميق المربع. تجارب عملية استخدمت لمقارنة المعتمد على طريقة العناصر المحددة استخدم إلجراء المحا ansysالمسحوب, برنامج اء,وقد تم استنتاج واثبات النتائج التي تم الحصول عليها من المحاكاة العددية. وعاء مربع خالي من العيوب تم إنتاجه مع توزيع مقبول السمك على طول الوع ات القاسية في هذا المنطقة و وقد وجد أيضا توافق بين نتائج التنبؤات العددية لتوزيع السمك ان الترقق غالبا ما يظهر عند زاوية الوعاء نتيجة للتشوه واالرتفاعات والتجارب العملية. default normal template n. h. abbas /al-khwarizmi engineering journal, vol.2, no. 1,pp 70-77 (2006) 70 al-khwarizmi engineering journal al-khwarizmi engineering journal, vol.2, no.1,pp 70-77, (2006) direction finding using gha neural networks n. h. abbas electrical eng. dept., college of eng./ university of baghdad (received 4 september 2005; accepted 4 april 2006) abstract: this paper adapted the neural network for the estimating of the direction of arrival (doa). it uses an unsupervised adaptive neural network with gha algorithm to extract the principal components that in turn, are used by capon method to estimate the doa, where by the pca neural network we take signal subspace only and use it in capon (i.e. we will ignore the noise subspace, and take the signal subspace only). keywords: direction of arrival (doa), generalized hebbian algorithm (gha), principal component analysis (pca), capon. 1.introduction estimating the doa of the source is a central problem in the array signal processing. many methods for estimation the doa have been proposed, including the maximum likelihood (ml) technique [1], the minimum variance method of capon [2], and the music method of schmidt [9]. the ml method has the best performance. because of high computational load of the multivariate nonlinear maximization problem involved, the ml technique did not becomes popular. suboptimal methods are more prevalent than the ml technique when the signal_to_noise ratio and number of samples are both not too small, because the suboptimal methods involve solving only a one-dimensional maximization problem and subspace (signal subspace or noise subspace). this paper uses adaptive algorithm for extracting the subspace information based on the pca neural network. where we extract the principal component (i.e. the signal subspace only) by using of gha algorithm with adaptive learning rate, which then used by a capon to find the doa. the mapping of this paper is as follows: section two provides some background information. where the data model and the subspaces are present. in section three an expression for the capon method is presented. in section four an expression for neural estimator is presented. in section five a computer simulation using matlab 6.0 is provided to support the theoretical observations. 2.general consideration assume that plane waves emitted by d1 narrow band sources impinged on a uniform circular array (uca) consisting of n. h. abbas /al-khwarizmi engineering journal, vol.2, no. 1,pp 70-77 (2006) 71 m sensors, and the doas of these sources (the azimuth angle is measured with respect to reference sensor, and elevation is measured with respect to z-axis as shown in figure (1) are [(θ1, φ1), (θ2, φ2),…, (θd, φd)].the array output vector at the k_th snapshot can then be expressed as x(k) =as(k)+n(k) (1) where s(k) is the d×1 vector of incident signals which are assumed to be zero mean stationary, complex and gaussian random processes n(k) is m×1 vector of additive noises which assumed to be zero mean random processes that are uncorrelated with each other and with the signals, and a is the steering (or direction) matrix given by a= [a(θ1,φ1), a(θ2,φ2),. . . a(θd,φd)].the steering vector corresponding to the i_th doa(θ,φ) is given by a(θi,φi)=[ a1(θ1,φ1)e -j*w 0 *τ1(θi,φi),. . ., am(θd,φd) e-j*w 0 *τm(θi,φi)] (2) where am (θi,φi) denotes the complex gain response of m_th sensor to a wave front arriving from direction (θi,φi),w0 denotes the center frequency of the signals ,and τm(θi,φi) denote the propagation delay between the sensors for a wave front impinging from direction (θi,φi) which is given by τi=j2πr/λsin (φi)cos (2πm/mθi) (3) where r is the radius of the circular array, and λ is the wavelength. the covariance matrix of the array signal vector is given by r =e[x(k)x(k) h] =asah +ỏn 2 i =rs +rn (4) where the superscript "h" denote the conjugate transpose .s=e[s (k) ×s (k) h] and ỏn 2 is the variance of the additive noise, let λ1≥ λ2≥ . . . λd≥ λd+1= . . . λm= ỏn 2, denote the eigenvalues of r and e1, e2. . .em denotes the corresponding eigenvectors. if the matrices es and en are formed as es= [e1, e2,. . ., ed] (5) and en=[ed+1, ed+2 . . .em] (6) then the linear span of es, known as the signal space, is same as spanned by the columns of a. the linear span of en, known as the noise subspace, is the orthogonal component of the signal subspace, then en h×a(θk,φk)=0 ,k=1,2,. . .,d. 3.the capon method the capon method tries to optimize the beamforming process according to the time varying covariance matrix .the spectrum is given by pmv (θ, φ) =1/(ah (θ, φ)r-1 a (θ, φ)) (7) the method minimizes the power contributed by the noise and signals originating from other direction the current steering direction. because r is consisting of a signal subspace and noise subspace, then we will take only the signal subspace rs, which is equal to es λs es (8) where λs is a diagonal matrix of the signal eigenvealues, and es is the corresponding eigenvectors as stated in (5).this feature of selection the signal subspace can be obtained by applying the principal component analysis (pca) neural network which extract the principal component i.e. λ1, λ2,. . . , λd and its corresponding eigenvectors e1,e2,. . . ,ed as illustrated in the next section. the number of sources is assumed known or we can find it by aic, or mdl [10]. 4.the neural estimator in the last years several papers dealing with pca neural networks [3],[4],[5],[6],[7],[8],[11]and [12] have discussed the advantages ,problems, and difficulties of such neural network (which is shown in figure 2) .in what follow we make use of an gha algorithm with adaptive learning rate . our neural estimator can be summarized in the following steps: n. h. abbas /al-khwarizmi engineering journal, vol.2, no. 1,pp 70-77 (2006) 72 1) the gha algorithms for signal samples x(n): ferom n=1 to n (i) set error signal e0(n)=x(n) for every neuron: from j=1 to d (2) set wj(0) randomly (3) set ηj in accordance with input variance for input samples: from n=1 to n (4) yj(n)=x(n)h×wj(n-1) (5) wj(n)= wj(n-1)+ηj yj(n)[ej-1(n)-wj(n-1) × yj(n)] if │ wj(k)wj(k-1) │ < є (where є is very small value) then (6) wj=wj(n); go to stable (7) decrease ηj exponentially stable: for input samples: from n=1 to n (8) set yj(n)=x(n)h×wj (9) set error ej(n)=ej-1(n)-yj(n)wj 2) wj qj ,and yj jv where qj are the eigenvectors corresponding to eigenvalues vj. 3) doa estimator, we use the modified capon method where we take the synaptic weight as the eigenvector of the signalsubspace and the output of the pca neural network as the squire roots of the output [7]. then doa are obtained as the peak location of the function according to the equation pmcapon (θ, φ) =1/(ah (θ, φ)řs -1 a (θ, φ)). (9) where řs -1=inverse of řs, and řs=∑ d i=1 (yj) 2 wi wi h . 5.simulation in our simulation we will use a uniform circular array consisting of eight sensors of radius 5λ/π as shown in figure 1. assuming two noncoherent signals with the signal to noise ratio equal to one are impinging on the array and the first source have elevation angle θ1=50,and azimuth angle φ1=30, while the second source have elevation angle θ2=60, and azimuth angle φ2=40.then by the use of the gha algorithm we will find the signal subspace, that in turn are used by capon method to find the doa of impending sources as shown in figure 3,4, and 5,where figure 3 show the doa(θi,φi),figure 4 , show the azimuth angle only, while figure 5 show the elevation angle only, where the angle will be corresponding to the peak locations in the n. h. abbas /al-khwarizmi engineering journal, vol.2, no. 1,pp 70-77 (2006) 73 spectrum of the capon as shown in previous figures. 6. discussion and conclusions this paper described a simple ,but efficient methods based on pca neural network to find the doa ,where by use of the pca neural network we don’t need to compute the correlation matrix r rather the first d eigenvectors of r are computed by the algorithm directly from the input data .the resulting computational saving can been enormous especially if the number of element m in the input vector is very large ,and the required number of the eigenvectors associated with the d largest eigenvalues of the correlation matrix r is small fraction of m..then the doa is achieved by incorporating the neural network with capon method, with use of signal subspace only. thus by the use of pca neural network we neglect part of the noise, due to the neglecting of the noise subspace. 7.refereneces [1] blester, y and macorski a., 1986 "exact maximum likelihood parameter estimation of superimposed exponential signals in noise", ieee trans. on acoustic, speech, and signal processing, vol. 34, pp. 1081-1089. [2] capon, j., 1969,"highresolution frequency – wavenumber spectrum analysis", proc. ieee, vol. 57, no. 8, august, pp. 1408 – 18. [3] chatterjee, c., kang, z., and roychowdhury, v., 2000, "algorithm for accelerated convergence of adaptive pca", ieee trans. on neural network, vol.11, no.2. [4] chchocki, a., kasprzak, w., and skarbek, w., 1996,"adaptive learning algorithm for principal component analysis with partial data", austrian society for syberenetic studies, vienna, austria. [5] chen ,t. ,and yan ,w. , 1998, "global convergence of oja׳s subspace algorithm for principal component extractions",vol. 9 ,no. 1. [6]chichoki, a., swiniarski, r., w., and bogner, r., e.,1996 ,"hierchical neural networks for robust pca computation of complex valued signals". [7] haykin, s., 1994, "neural network, a comprehensive foundation", © by macmillan college publishing company. inc. [8] kung, s., y., 1993, "digital neural network", © by ptr prentice hall, inc. [9] schmidt, r.o., 1986, "multiple emitter location and signal parameter estimation ", ieee trans.on antenna and propagation, vol. 34, no. 3, pp. 276 – 80. [10] wax, m., .and kailath, t., 1985, " detection of signals by information theoretic criteria", ieee trans. on acoustic, speech, and signal processing, vol. assp-33, no.2. [11] weinglessel, a., and hornik, k., 2000, "local pca algorithms", ieee trans. on neural network, vol. 11, no.6. [12] weinglessel, a., and hornick, k., 1996, "neural network algorithms for online principal component analysis and singular value decomposition ", tuien-central for computational intelligence. n. h. abbas /al-khwarizmi engineering journal, vol.2, no. 1,pp 70-77 (2006) 74 x z θi φi ith plane wave figure 1: uniform circular array the reference sensor xn . x2 y1 y2 ym    . . . . . figure 2: the pca neural network. x1 n. h. abbas /al-khwarizmi engineering journal, vol.2, no. 1,pp 70-77 (2006) 75 figure 4:the azimuth angle in degree the azimuth angle in degree t h e n o rm al iz ed s p ec tr u m figure 3: the doa( , ). n. h. abbas /al-khwarizmi engineering journal, vol.2, no. 1,pp 70-77 (2006) 76 t h e n o rm al iz ed s p ec tr u m figure 5:the elevation angle in degree n. h. abbas /al-khwarizmi engineering journal, vol.2, no. 1,pp 70-77 (2006) 77 مع الشبكات العصبية ghaايجاد االتجاه باستخدام خوارزمية نزار هادي عباس ة /جامعة بغدادكلية الهندس /قسم الهندسة الكهربائية :الخالصة خوارزمياة ماع الاذاتي التعنايم ذات العصابية الشابكة اساتعمننا حياث. الوصاو زاوياة إليجااد عصبية شبكة تصميم تم البحث هذا في gha كاابون بطريقاة تستخدم بدورها التيو الدائري الترتيب ذات الهوائيات قب من ةالمستنم لإلشارة األساسية المركبات النتزاع (كاابون بطريقاة يساتخدم بادوره الاذيتاخاذ جازم مان ف اام االشاارة pca أ العصابية الشبكةان حيث. الوصو زاوية يجادإل .ال و ام ف ام هم وت موفق al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 7, no. 4, pp 27-40 (2011) control on a 2-d wing flutter using an adaptive nonlinear neural controller mauwafak a. tawfik* mohammed i. mohsin* hayder s. abd al-amir** * department of mechanical engineering /university of technology ** department of mechanical engineering /institute of technology email: has_04@yahoo.com (received 23 february 2011; accepted 6 july 2011) abstract an adaptive nonlinear neural controller to reduce the nonlinear flutter in 2-d wing is proposed in the paper. the nonlinearities in the system come from the quasi steady aerodynamic model and torsional spring in pitch direction. time domain simulations are used to examine the dynamic aero elastic instabilities of the system (e.g. the onset of flutter and limit cycle oscillation, lco). the structure of the controller consists of two models :the modified elman neural network (menn) and the feed forward multi-layer perceptron (mlp). the menn model is trained with off-line and on-line stages to guarantee that the outputs of the model accurately represent the plunge and pitch motion of the wing and this neural model acts as the identifier. the feed forward neural controller is trained off-line and adaptive weights are implemented on-line to find the flap angles, which controls the plunge and pitch motion of the wing. the general back propagation algorithm is used to learn the feed forward neural controller and the neural identifier. the simulation results show the effectiveness of the proposed control algorithm; this is demonstrated by the minimized tracking error to zero approximation with very acceptable settling time even with the existence of bounded external disturbances. keywords: adaptive nonlinear control, flutter, nonlinear system, neural network. 1. introduction the performance of aircraft is often limited by adverse aero elastic interactions such as flutter. flutter is defined as a dynamic instability of a flight vehicle associated with the interaction of aerodynamic, elastic, and inertial forces. if flutter can be controlled at cruise speeds, lighter wings can be designed and consequently more efficient airplanes. it is therefore, in the aircraft designer’s best interest to design innovative ways in which flutter can be controlled without making the resulting structure too heavy the nonlinear flutter models behavior is close to the systems in nature. however, the control on the flutter resulting from nonlinear models is not an easy task and need more development. in reality nonlinearities may be presented in various forms [1,2] .recently, many researches in this field proposed different nonlinear flutter controllers, where the linear controller could not effectively suppress the flutter [3]. palaniappan, et al. [4] developed a feedback algorithm for the control of nonlinear flutter. the actuators are jets in the walls through which there is a small mass flow, either by way of blowing or suction. afkhami and alighanbair [5] presented nonlinear controller to control flutter. integral-input-to-state stability concept is utilized for the construction of a feedback controller. haiwei and jinglong [6] proposed the robust flutter analysis of a nonlinear 2-d wing section with structural and aerodynamic uncertain using μ-method. the parametric uncertainty was adopted to describe the uncertainties in structure and aerodynamics. the nonlinear system was linearized at equilibrium point and μ analysis is performed for a set of values of flow velocities to generate the lower and upper bounds of robust flutter speed. for a typical section with a mailto:has_04@yahoo.com mauwafak a. tawfik al-khwarizmi engineering journal vol. 7, no. 4, pp 27-40(2011) 28 structural nonlinearity, zeng and singh [7] have derived a nonlinear adaptive control based on the model reference adaptive control theory. the system design was based on an output feedback method that eliminates the requirement for full state reconstruction. however, the derived control system exhibits somewhat larger flap deflections in simulations than others. the neural networks were introduced in aero elastic field as nonlinear controller or flutter prediction device. melin and castillo[8] combined adaptive model-based control using neural networks with the method for modeling using fuzzy logic, and fractal theory to obtain a new hybrid neuro-fuzzy-fractal method for the control of nonlinear dynamic aircraft. the adaptive controller can be used to control chaotic and unstable behavior in aircraft systems. chen, et al. [9] presented an approach using artificial neural networks (ann) algorithm for predicting the flutter derivatives of rectangular section models without wind tunnel tests. the database of flutter derivatives was identified from a backpropagation (bp) ann model that is built using experimental dynamic responses of rectangular section models in smooth flow as the input/output data. these limited sets of database are employed as input/output data to establish a prediction ann frame model to further predict the flutter derivatives for other rectangular section models without conducting wind tunnel tests. the results presented indicate that this ann prediction scheme works reasonably well. the contribution of the present work is the utilization of a relatively simple approximation neural network to identify the posture of the non linear 2-d wing system and to design an adaptive nonlinear neural controller. 2. method of analysis 2.1. two dimensional aero elastic wing model the 2-d aero elastic wing section is shown in figure (1). the governing equations of motion are provided in [5] and are given as: lhkhcbmxhm ha −=+++ ..... hα mkchbmxi a =+++ αααα α )( . a .... …(1) where h is the plunge displacement and α is the pitch angle. in eq. (1), m is the mass of the wing; b is the semichord of the wing; i is the moment of inertia; xα is the nondimensionalized distance of the center of mass from the elastic axis; kh is plunge stiffness coefficient; )(ααk is nonlinear pitch stiffness ch and cα are plunge and pitch damping coefficients, respectively; l and m are the aerodynamic lift and moment. in the present work, the nonlinear quasi steady aerodynamic model including stall effect [10] and flap angle effect [5] is as follow 22 2 11 23 3 2 )( βρ βρααρ β βα l leffeffl bcu bcucbcul + +−= 22 22 11 223 3 22 )( βρ βρααρ β βα m meffeffm cbu cbuccbum + +−= …(2) where ρ is the air density, u is the flow velocity, and clα and cmα are the lift and moment coefficients. clβ and cmβ are the lift and moment coefficients per flap angle. β1 and β2 are flap angles. c3 is a nonlinear parameter associated with stall model. αeff is the effective angle of attack defined by /uα-d)b.(/uhα .. eff 50++=α …(3) where d is the non dimensional distance from the mid chord to the elastic axis. parameter c3 is defined as follow for naca 0012 airfoil (a symmetric wing section by national advisory committee for aeronautics), c3 = 0.00034189(180/π)3/clα …(4) this aerodynamic model is valid for αeff ∈ (−11, 11) degree. the function kα(α) is considered as a polynomial given by [10] kα(α) = kα1 + kα2α + kα3α2, … (5) where kαj , j = 1, 2, 3 are constants. fig.1. two-dimensional aero elastic model. mauwafak a. tawfik al-khwarizmi engineering journal vol. 7, no. 4, pp 27-40(2011) 29 0 5 10 15 20 25 30 35 40 45 50 -0.1 -0.05 0 0.05 0.1 time (sec) al fa (r ad ) u=9.8 m/sec 0 5 10 15 20 25 30 35 40 45 50 -4 -3 -2 -1 0 1 2 3 4 x 10 -3 time (sec) pl un ge (m ) u=9.8 m/sec 0 5 10 15 20 25 30 35 40 45 50 -0.1 -0.08 -0.06 -0.04 -0.02 0 0.02 0.04 0.06 0.08 time (sec) al fa (r ad ) u=9.9 m/sec 0 5 10 15 20 25 30 35 40 45 50 -3 -2 -1 0 1 2 3 x 10 -3 time (sec) pl un ge (m ) u=9.9 m/sec 2.2. nonlinear flutter analysis the proposed nonlinear controller must work in the unstable region .time domain simulation is used to examine the dynamic aeroelastic instabilities of the system (e.g. the onset of flutter and limit cycle oscillation (lco)) [11].the simulation is performed by solving eqs (1-5) and using runge kutta method for different velocities and initial conditions.it was found that lco appears at u=9.9m/sec and never appear at speed less than what ever the initial conditions. therefore the flutter speed is 9.9m/sec and the proposed nonlinear controller must give a good performance at speed higher than that value (unstable region). figure (2) shows the plunge h and pitch angle α responses at speed 9.8m/sec while the responses at speed 9.9m/sec are shown in the figure (3) the time responses of the plunge h and pitch angle α corresponding to the uncontrolled system at u=30m/sec, and 40m/sec are shown in figure (4).clearly, the system responses exhibit lco behaviour. it is clear that the amplitudes of lco increase with the velocity. the function of controller is to reduce amplitudes of lco at short settling time in order to eliminate the risk of damage of wing structure. fig.2. time history of pitch angle and plunging at 9.8 m/s speed and initial conditions ( radh 1.0)0(;0)0( == α ). fig.3. time history of pitch angle and plunging at 9.9 m/s speed and initial conditions () radh 1.0)0(;0)0( == α . mauwafak a. tawfik al-khwarizmi engineering journal vol. 7, no. 4, pp 27-40(2011) 30 2.3. adaptive nonlinear neural control methodology the approach to control wing motion depends on the available information about the system and the control objectives. the 2-d wing system is considered as modified elman recurrent neural networks model. the first step in the procedure of the control structure is the identification of nonlinear dynamics of 2-d wing system from the input-output data. then a feed forward neural controller is designed using feed forward multilayer perceptron neural network to find flap angles that control the plunge and pitching wing motion. the proposed structure of the adaptive nonlinear neural controller can be given in the form of block diagram as shown in figure (5). it consists of: 1neural network identifier of 2-d wing system . 2feed forward neural controller. in the following sections, each part of the proposed controller will be explained in details. 2.4. nonlinear 2-d wing system neural network identifier the modified elman recurrent neural network model is applied to construct the 2-d wing system neural network identifier as shown in figure (5). the nodes of input, context, hidden and output layers are highlighted. the network uses two configuration models, series-parallel and parallel identification structures, which are trained using dynamic back-propagation algorithm. fig.4. time history of pitch angle and plunging at 30m/s and 40m/sec speed with initial conditions ( radh 1.0)0(;0)0( == α ). 0 5 10 15 20 25 30 35 40 45 50 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 time (sec) al fa (r ad ) u=30 m/sec 0 5 10 15 20 25 30 35 40 45 50 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 time (sec) al fa (r ad ) u=40 m/sec 0 5 10 15 20 25 30 35 40 45 50 -0.03 -0.02 -0.01 0 0.01 0.02 0.03 time (sec) pl un ge (m ) u=40 m/sec 0 5 10 15 20 25 30 35 40 45 50 -0.015 -0.01 -0.005 0 0.005 0.01 0.015 0.02 time (sec) pl un ge (m ) u=30 m/sec mauwafak a. tawfik al-khwarizmi engineering journal vol. 7, no. 4, pp 27-40(2011) 31 fig.5. the proposed structure of the adaptive nonlinear neural controller for the 2-d wing . fig.6. the modified elman recurrent neural networks acts as the plunging and pitch motion of the wing. o cγ mauwafak a. tawfik al-khwarizmi engineering journal vol. 7, no. 4, pp 27-40(2011) 32 the structure shown in figure (6) is based on the following equations: }),(),({)( vbbiaskvckgvhfk oγγ = …(6) )),(()( wbbiaskwko γ= …(7) where vh,vc and w are weight matrices, vb and wb are weight vectors and f is a non-linear vector function. the multi-layered modified elman neural network, shown in figure (7), is composed of many interconnected processing units called neurons or nodes. the network weights are denoted as follows: vh :weight matrix of the hidden layers. vc : weight matrix of the context layers. vb : weight vector of the hidden layers. w : weight matrix of the output layer. wb : weight vector of the output layer. l : denotes linear node. h : denotes nonlinear node with sigmoidal function. fig.7. the multi-layer perceptron neural networks of the feed forward neural controller. in order to improve the ability of network memory, self-connections, with fixed value λ , are introduced into the context units of the network to give these units a certain amount of inertia [13]. the introduction of self-connections in the context units increases the possibility of modelling highorder systems by elman network. the output of the context unit in the modified elman network is given by: )1()1()( −+−= kkk c o c o c ργλγγ …(8) where )(ko cγ and )(kcγ are the outputs of the context and hidden units respectively. λ is the feedback gain of the self-connections and ρ is the connection weight from the hidden units (jth) to the context units (cth) at the context layer. the value of λ and ρ are selected randomly between (0 and 1) [13] . to explain these calculations, consider the general jth neuron in the hidden layer. the inputs to this neuron consist of an i– dimensional vector, where i is the number of the input nodes. each of the inputs has vh and vc weights associated with it. vb is the weight vector for the bias input set equal to -1 to prevent the neurons quiescent. the first calculation within the neuron consists of calculating the weighted sum jnet of the inputs as [13 and 14]: j c c o cjc nh i ijij vbbiasvcgvhnet ×+×+×= ∑∑ == 11 γ …(9) where j.is the number of the hidden nodes, c is the number of the context nodes and g is the input vector. the outputs of the identifier are the modelling plunge and pitch motion and are defined as: t mmm hq ),( α= where mh : plunge motion of the wing identifier. mα pitch motion of the wing identifier. the learning algorithm will be used to adjust the weights of dynamical recurrent neural network. dynamic back propagation algorithm is used to train the elman network. the sum of the square of the differences between the desired outputs thq ),( α= and neural network identifier outputs t mmm hq ),( α= is given by equation (10). ))()(( 2 1 1 22∑ = −+−= np i mmhhe αα …(10) where np is the number of patterns. the connection matrix between hidden layer and output layer is kjw kj kj w ekw ∂ ∂ −=+∆ η)1( …(11) where η is the learning rate. kj k k k k m mkj w net net o o kq kq e w e ∂ ∂ ∂ ∂ ∂ +∂ +∂ ∂ = ∂ ∂ )1( )1( …(12) kjkj ekw ××=+∆ γη)1( …(13) )1()()1( +∆+=+ kwkwkw kjkjkj …(14) the connection matrix between the input layer and hidden layer is jivh mauwafak a. tawfik al-khwarizmi engineering journal vol. 7, no. 4, pp 27-40(2011) 33 ji ji vh ekvh ∂ ∂ −=+∆ η)1( …(15) ji j j j j k k k k m mji vh net net net net o o kq kq e vh e ∂ ∂ ∂ ∂ ∂ ∂ ∂ ∂ ∂ +∂ +∂ ∂ = ∂ ∂ γ γ )1( )1( …(16) ∑ = ×′×=+∆ k k kjkijji wegnetfkvh 1 )()1( η …(17) )1()()1( +∆+=+ kvhkvhkvh jijiji …(18) the connection matrix between context layer and hidden layer is jivc jc jc vc ekvc ∂ ∂ −=+∆ η)1( …(19) jc c c j j k k k k m mjc vc net net net net o o kq kq e vc e ∂ ∂ ∂ ∂ ∂ ∂ ∂ ∂ ∂ +∂ +∂ ∂ = ∂ ∂ γ γ )1( )1( …(20) ∑ = ×′×=+∆ k k kjk o cjjc wenetfkvc 1 )()1( γη …(21) )1()()1( +∆+=+ kvckvckvc jcjcjc …(22) 2.5. feed forward neural controller the feed forward neural controller (ffnc) is essential to stabilize the tracking error of the wing system when the response of the wing is drifted from the desired condition during transient state and kept the steady-state tracking error at zero. the controller generates flap angles )(1 kβ and )(2 kβ control action that minimizes the cumulative error between the desired condition and the output response of the wing. the ffnc is supposed to learn the adaptive inverse model of the wing with off-line and on-line stages to calculate wing's reference input flap angle and keep the wing stable without flutter state in the presence of any disturbances or dynamics parameters changing. to achieve ffnc, a multi-layer perceptron model is used as shown in figure (7). the network notations are as follows: vffc : weight matr ix of the hidden layers. bffcv : weight vector of the hidden layers. wffc : weight matrix of the output layer. ffcwb : weight vector of the output layer. to explain these calculations, consider the general a th neuron in the hidden layer shown in figure (7.) the inputs to this neuron consist of an n–dimensional vector, where n is the number of the input nodes. each input has an associated weight of vffc . the first calculation within the neuron is to calculate the weighted sum of the inputs, anetc as [15, 16 and 17]: a nhc a nana vbffcbiaszvffcnetc ×+×= ∑ =1 …(23) where nhc is the number of the hidden nodes. next, the output of the neuron ah is calculated as the continuous sigmoid function of the anetc as: )( aa netchc =γ …(24) 1 1 2)( − + = − anetca e netch …(25) once the outputs of the hidden layer have been calculated, they are passed to the output layer. in the output layer, two linear neurons are used to calculate the weighted sum netco of its inputs, which are the output of the hidden layer as: b nhc a abab wbffcbiascwffcnetco ×+×= ∑ =1 γ …(26) where bawffc are the weights between the hidden neuron acγ and the output neurons. then the sum ( bnetco ) will be passed through a linear activation function of slope 1; another slope can be used to scale the output, as: )( bb netcoloc = …(27) the outputs of the feedforward neural network controller represent flap angles, )(1 kβ and )(2 kβ . the training of the feedforward neural controller is performed off-line as shown in figure (8). and adaptive weights are adapted on-line. it depends on the posture neural network identifier to find the wing jacobian through the neural identifier model. this approach is currently considered as one of the better approaches that can be followed to overcome the lack of initial knowledge. mauwafak a. tawfik al-khwarizmi engineering journal vol. 7, no. 4, pp 27-40(2011) 34 the dynamic back propagation algorithm is employed to realize the training the weights of the feedforward neural controller. the sum of the square of the differences between the desired posture t rrr hq ),( α= and neural network posture t mmm hq ),( α= is: ))()(( 2 1 1 22∑ = −+−= npc i mrmr hhec αα …(28) where npc is the number of patterns. to achieve equation (28) a modified elman neural network will be used as posture identifier. this task is carried out using an identification technique based on series-parallel and parallel configuration with two stages to learn the posture identifier. the first stage is an off-line identification, while the second stage is an on-line modification of the weights of the obtained wing neural identifier. the on-line modifications are necessary to keep tracking any possible variation in the dynamic parameters of the 2-d wing system. back propagation algorithm (bpa) is used to adjust the weights of the posture neural identifier to learn dynamic of the 2-d wing system by applying a simple gradient decent rule. the connection matrix between the hidden layer and the output layer is bawcont ba ba wffc eckwffc ∂ ∂ −=+∆ η)1( …(29) ba b b b b b b m mba wffc netc netc oc oc k k kq kq ec wffc ec ∂ ∂ ∂ ∂ ∂ ∂ ∂ +∂ +∂ ∂ = ∂ ∂ )( )( )1( )1( β β …(30) ab b b b m mba cnetcf oc k k kq kq ec wffc ec γ β β )( )( )( )1( )1( ′ ∂ ∂ ∂ +∂ +∂ ∂ = ∂ ∂ …(31) )1( ))()(( 2 1 )1( 22 +∂ −+−∂ = +∂ ∂ ∑ kq hh kq ec m mrmr m αα …(32) )( )1( k kqjacobian b m β∂ +∂= …(33) )( )( )( )1( )( )1( k net net net net ko ko kq k kq b j j j j k k k k m b m β γ γβ ∂ ∂ ∂ ∂ ∂ ∂ ∂ ∂ ∂ +∂ = ∂ +∂ …(34) for linear activation function in the outputs layer: )()( )1( k net net net k kq b j j j j k b m β γ γβ ∂ ∂ ∂ ∂ ∂ ∂ = ∂ +∂ …(35) for nonlinear activation function in the hidden layer: )( )( )( )1( 1 k net netfw k kq b j j k k kj b m ββ ∂ ∂ ′= ∂ +∂ ∑ = …(36) ∑ ∑ = = ′= ∂ +∂ nh j k k kjjbj b m wvhnetf k kq 1 1 )( )( )1( β …(37) substituting equations (32 and 37) into equation (31), )1( +∆ kwffcba becomes: )))1(( ))1((()()1( 2 1 1 jm jm nh j jbjaba wke wkehvhnetfckwffc ++ +′×=+∆ ∑ = α ηγ …(38) )1()()1( +∆+=+ kwffckwffckwffc bababa …(39) the connection matrix between the input layer and the hidden layer is anvffc an an vffc eckvffc ∂ ∂ −=+∆ η)1( …(40) fig.8. the structure of the feed forward neural controller for wing model. mauwafak a. tawfik al-khwarizmi engineering journal vol. 7, no. 4, pp 27-40(2011) 35 × ∂ ∂ × ∂ ∂ × ∂ ∂ = ∂ ∂ b b b b ban netc oc oc k k ec vffc ec )( )( β β an a a a a b vffc netc netc c c netc ∂ ∂ × ∂ ∂ × ∂ ∂ γ γ …(41) × ∂ ∂ ∂ +∂ +∂ ∂= ∂ ∂ b b b m man oc k k kq kq ec vffc ec )( )( )1( )1( β β an a a a a b b b vffc netc netc c c netc netc oc ∂ ∂ × ∂ ∂ × ∂ ∂ × ∂ ∂ γ γ …(42) na b b ba b m man znetcfwffc k kq kq ec vffc ec ×′×× ∂ +∂ +∂ ∂ = ∂ ∂ ∑ = )( )( )1( )1( 1β …(43) substituting equations (32 and 37) into equation (43), )1( +∆ kvffcan becomes: )))1(())1((()( )()1( 21 1 1 1 jmjm nh j i i jij b b baanan wkewkehvhnetf wffcnetcfzkvffc +++′ ′=+∆ ∑ ∑ ∑ = = = α η …(44) the b and i are equal to two because there are two outputs in the feedforward neural controller. )1()()1( +∆+=+ kvffckvffckvffct ananan …(45) once the feedforward neural controller has learned, it generates the flap control action to keep the output of the wing at reference value and to overcome any external disturbances during motion. 3. results and discussion the proposed controller is verified with computer simulation using c++ program. the dynamics model of 2-d wing system described in section 2 is used. the simulation is carried out by tracking a desired plunging and pitch angle during flutter or limit cycle oscillation condition. the parameter values of a two degree of freedom (2dof) airfoil system (typical section model) are taken from [5] see table (1). the fist stage of operation is to set the position (plunging motion) and orientation about the elastic axis (pitch angle) neural network identifier. this task is performed using seriesparallel and parallel identification technique configuration with modified elman recurrent neural networks model. the identification scheme of the nonlinear mimo (2-dof) airfoil system are needed to input-output training data pattern to provide enough information about dynamics (2dof) wing model to be modelled. this can be achieved by injecting a sufficiently rich input signal to excite all process modes of interest while also ensuring that the training patterns adequately covers the specified operating region. a hybrid excitation signal has been used for the 2-d wing model. figure (9) show the input signals )(1 kβ and )(2 kβ ,. table 1, system parameters [5] b 0.135 m d -0.45 m 12.387 kg xa 0.25 i 0.065 kg.m2 kh 2844.4 n/m kα(α) 12.77+53.47α+1003α2 n/rad [11] ch 27.43 cα 0.036 ρ 1.225 kg/m3 clα 6.28 cmα -0.635 clβ1 3.358 c lβ2 3.458 c mβ1 -0.635 c mβ2 -0.735 the training set is generated by feeding a pseudo random binary sequence (prbs) signals, to the model and measuring its corresponding outputs, position (plunging motion) and orientation (pitch angle), with a sampling time of 0.01 second. this value was found adequate for the stability and convergence of solution. back propagation learning algorithm is used with the modified elman recurrent neural network of the structure 5-7-7-2. the number of nodes in the input, hidden, context and output layers are 5, 7, 7 and 2 respectively as shown in figure (6). fig.9. the prbs input flap angles signals used to excite the wing model. mauwafak a. tawfik al-khwarizmi engineering journal vol. 7, no. 4, pp 27-40(2011) 36 0 20 40 60 80 100 120 140 160 180 200 -0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 sampling time 0.01 sec pl un gi ng (m ) h hm a training set of 200 patterns has been used with a learning rate of 0.1 and variable speed inputs u=[25, 30, 35, 40 and 45] m/sec. after 5439 epochs, the identifier outputs of the neural network, position (plunge motion) and orientation about (pitch angle), are approximated to the actual outputs as shown in figure (10). the objective cost function mse is less than 16×10-5 as shown in figure (11). parallel configuration is used to guarantee the similarity between the outputs of the neural network identifier and the actual outputs of the plunging motion and pitch angle of the wing. at 3859 epochs the same training set patterns has been achieved with an mse less than 1.9×10-6. the testing set is generated by difference feeding a prbs signals as shown in figure (12), and it is applied to the system. figure (13) compare the time response of the parallel mode output with the actual plant output, and there is excellent identification. fig.10. the response of the neural network identifier with the actual 2-d wing model output for the learning set. fig.13. the response of the neural network identifier with the actual 2-d wing model output for the testing set. fig.12. the prbs input flap angles signals used for testing 2-d wing identifier model. fig.11. the mse of the cost function. 0 0.0001 0.0002 0.0003 0.0004 0.0005 0.0006 0.0007 0.0008 0.0009 0.001 0 600 1200 1800 2400 3000 3600 4200 4800 5400 epochs m s e mauwafak a. tawfik al-khwarizmi engineering journal vol. 7, no. 4, pp 27-40(2011) 37 the final stage of the proposed controller is feedforward neural controller. it uses multi-layer perceptron neural network 6-13-2 as shown in figure (7). the desired conditions has been learned by the feedforward neural controller with off-line and on-line adaptation stages using back propagation algorithm as shown in figure (8) to find the suitable control action. the controller performance is simulated at three values of the flight speed (30, 35, 45 m/sec) in unstable region and at different initial conditions of plunging motion and pitch angle. figure (14) shows the closed loop responses for the controlled 2-d wing system. the controller reach the requirements and the closed-loop simulation obtained is stable .the over shoot and settling time increase slightly with the increasing of the velocity. also the oscillation during the transient period appears with the increasing of the velocities, but its amplitude is small and converge of desired condition is quick with settling time 0.4sec at high velocity u=40m/sec. in figure (15) the responses of the controller effort (flap angles) at u=30m/sec and 40m/sec are shown. it is clear that the control action β1 has large values in comparing with another control action β2 .also the control actions never exceed ± 0.3 rad. the values of flap angles are limited from -0.3 to 0.3 rad. to make the controller works in logical limits. the values of the initial conditions are varying to make the nonlinear stable or unstable, so the present controller performance is tested at different initial conditions as shown in figure (16). when the initial values of plunging and pitch angle increase the over shoot and the oscillation increase during the transient period. the plunging initial value has large effect on the responses than pitch angle initial value. but the present controller can give acceptable performance and reaches to desired condition at very short settling time about 0.2sec. this result compares very well with reference [5]. 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 -10 -8 -6 -4 -2 0 2 4 x 10 -3 time (sec) pl un gi ng (m ) u=30m/sec u=35m/sec u=40m/sec 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 -0.04 -0.02 0 0.02 0.04 0.06 0.08 0.1 time (sec) al fa (r ad ) u=30m/sec u=35m/sec u=40m/sec fig.14. system responses with controller at different speed and initial conditions ( radh 1.0)0(;0)0( == α ). fig.15. control efforts at different speed and initial conditions ( radh 1.0)0(;0)0( == α ). mauwafak a. tawfik al-khwarizmi engineering journal vol. 7, no. 4, pp 27-40(2011) 38 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 -0.06 -0.04 -0.02 0 0.02 0.04 0.06 0.08 0.1 time (sec) al fa (r ad ) u=40m/sec 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 -8 -6 -4 -2 0 2 4 x 10 -3 t ime (sec) pl un gi ng (m ) u=40m/sec finally, to investigate the present controller performance at difficult conditions, the disturbance action is introduced on the wing model at high velocity u=40m/sec. in figure (17) the responses of controller with sinusoid disturbance has been shown. the amplitude of disturbance is taken as 300% the maximum values of control actions and frequency 10 hz. in spite of the existence of bounded disturbances the adaptive learning and robustness of neural controller show small effect of these disturbances. the controller achieves the desired condition with very small fluctuation. for plunging and pitch motions the fluctuation was 0.00055 m and 0.0068 rad. respectively. these values are less than the maximum fluctuation for the same wing section [18] (about 0.048b for plunging and 0.024 rad. for pitch motion). 4. conclusions in the current work, it has been shown that the proposed controller has the capability to generate fig.17. system responses with sinusoid disturbanceat initial conditions ( radh 1.0)0(;0)0( == α ). smooth and suitable flap commands, 1β and 2β without sharp spikes. moreover, it has the capability of effectively eradicating the tracking errors for the 2-d wing model. the principal conclusions may be summarized as follows: excellent identification is achieved when comparing the time response of the parallel mode output with the actual plant output. the controller reach the requirements and the closed-loop simulation obtained is stable. the over-shoot and settling time increase slightly with the velocity. the amplitude of oscillation during the transient period is small and converge to desired condition. the controller worked in logical limits, the control action never exceeds ± 0.3 rad. the plunging initial value has large effect on the response than pitch angle initial value. simulation results show that the proposed controller is robust and effective in comparison with the controller in [5] in terms of fast response with minimum settling times and minimum fig.16. system responses with controller at different initial conditions. mauwafak a. tawfik al-khwarizmi engineering journal vol. 7, no. 4, pp 27-40(2011) 39 tracking error despite the presence of bounded external disturbances. 5. references [1] shams sh., sadr m.h.,and haddadpour h. " nonlinear aeroelastic response of slender wings based on wagner function", thinwalled structures ,vol 46 (2008) pp.1192– 1203 [2] woolston ds, runyan hl,and andrews re. "an investigation of certain types of structural nonlinearities on wing and control surface flutter" j aeronaut sci, vol 24,(1957),pp.57–63. [3] frampton, k.d., and clark, r.l. "experiments on control of limit cycle oscillations in a typical section" , aiaa paper 99-1466’. proc.40th structures, structural dynamics and material conf., st. louis, mo, (1999), pp. 2195–2055 [4] palaniappan k, sahu p.and alonso j.j " design of adjoint based laws for wing flutter control",american institute of aeronautics and astronautics paper aiaa(2009)-148. [5] afkhami s. and . alighanbari h. "nonlinear control design of an airfoil with active flutter suppression in the presence of disturbance", iet control theory appl., vol. 1, no. 6, november (2007) [6] haiwei, y. and jinglong h. " robust flutter analysis of a nonlinear aeroelastic system with parametric uncertainties", aerospace science and technology , vol 13 ,(2009) pp.139–149 [7] zeng, y., and singh, s.n "output feedback variable structure adaptive control of an aeroelastic system", j. guidance control dyn.,vol 21, (1998), pp. 830–837 [8] melin p.and castillo o." adaptive intelligent control of aircraft systems with a hybrid approach combining neural networks, fuzzy logic and fractal theory", applied soft computing vol3, (2003) pp.353–362 [9] chen c., wu j.and chen j. " prediction of flutter derivatives by artificial neural networks", journal of wind engineering and industrial aerodynamics ,vol. 96 ,(2008), pp.1925–1937 [10] demenkov m. "form local to global stabilizility of aeroelastic oscillation",18th ieee international conference on control apllictions ,saint petersburg ,russia, 2009. [11] abbas1 l k, chen1 q. and milanese a. " non-linear aeroelastic investigations of store(s)-induced limit cycle oscillations", j. aerospace engineering vol. 222 part g (2008). [12] ogata k.modern control engineering, prentice-hall international.inc(1970) [13] pham d. t. and xing l. " neural networks for identification, prediction and control", springer, (1995). [14] s. omatu, m. khalid, and r. yusof "neurocontrol and its applications" london: springer-velag, 1995. [15] zurada j. m., introduction to artificial neural systems. jaico publishing house, pws pub co. (1992). [16] k. s. narendra and k. parthasarathy, “identification and control of dynamical systems using neural networks,” ieee trans. neural networks, vol. 1,pp. 4-27, 1990. [17] k. s. narendra and k. parthasarathy, “gradient methods for the optimization of dynamical systems containing neural networks,” ieee trans. neural networks, vol. 2 no. 2, pp. 252-262, 1991. [18] abu-tabikh,m.i." modeling of steady and unsteady tturblunent boundary layer separation using vortex hybrid method ", ph.d thesis, department of mechanical engineering, u.o.t, baghdad,1997. )2011( 27 40 ، صفحة4 ، العدد7مجلة الخوارزمي الھندسیة المجلد موفق علي توفیق 40 مسیطرثنائي األبعاد باستخدام جناح السیطرة على رفرفة متكیفعصبي ال خطي **األمیر حیدر صباح عبد * محسن إدریسمحمد . د * موفق علي توفیق. د الجامعة التكنولوجیة /قسم ھندسة المكائن والمعدات * بغداد -معھد التكنولوجیا /قسم الھندسة المیكانیكیة ** الخالصة ت الالخطی ة ف ي منظوم ة الم ؤثرا تنش ا .ثن ائي األبع اد جن اح مسیطر عصبي الخطي متكیف للسیطرة عل ى الرفرف ة لنم وذج اقتراح البحث تم في ھذا غی ر مس تقر م ن خ الل فح ص ت م تحدی د المنطق ة الت ي یك ون فیھ ا النظ ام .الت أرجح شبھ المستقر والنابض أاللتوائي باتج اه الجناح من النموذج االیرودینامي من نموذجین ھما الشبكة العصبیة تتكون ھیكلیة المسیطر. رفرفة والتذبذب الدوري المحدداستجابتھ مع الزمن حیث تم إیجاد السرعة التي تبدأ عندھا ظاھرة ال الخ ط مرحل ة و ل ق الخ ط المغ ھم ا مرحل ة ن م رحلتی ف ي ) menn( النم وذج لقد تم تأھیل. )mlp(و بیرسبتون متعدد الطبقات ) menn(المحسنة أللمن ت م .حركة التأرجحیة والحركة العمودیة لتكوین النموذج العص بي المع رف مخرج منظومة الجناح وھومع العصبي خرج النموذجم المفتوح لضمان تطابق الخ ط المفت وح إلیج اد زاوی ة الخافق ة المطلوب ة الت ي من خالل الخط المغلق ثم تم تحدیث األوزان لھذا المسیطر م ن خ الل تأھیل المسیطر العصبي األمامي نتائج المحاكاة لھذا المسیطر العصبي الالخطيكانت . االنتشار الخلفي لتأھیل النموذجینتم استخدام خوارزمیة .والحركة العمودیة التأرجحتسیطر على حركة .وضاء خارجیةمع وجود ض لى صفر وبزمن استقرار مناسبمن خالل تقلیل الرفرفة إ فعالة w. a. mahmoud /al-khwarizmi engineering journal ,vol.1, no. 1,pp 26-37 (2005) 26 al-khwarizmi engineering journal al-khwarizmi engineering journal, vol.1, no.1,pp 26-37, (2005) the determination of critical-sampling scheme of preprocessing for multiwavelets decomposition as 1st and 2nd orders of approximations. w. a. mahmoud* z. j. m. saleh** n. k. wafi* electrical engineering dept / college of engineering /university of baghdad*. information engineering dept ./ al-khwarizmi engineering college / university of baghdad** abstract one of the important differences between multiwavelets and scalar wavelets is that each channel in the filter bank has a vector-valued input and a vector-valued output. a scalar-valued input signal must somehow be converted into a suitable vector-valued signal. this conversion is called preprocessing. preprocessing is a mapping process which is done by a prefilter. a postfilter just does the opposite. the most obvious way to get two input rows from a given signal is to repeat the signal. two rows go into the multifilter bank. this procedure is called “repeated row” which introduces oversampling of the data by a factor of 2. for data compression, where one is trying to find compact transform representations for a dataset, it is imperative to find critically sampled multiwavelet transforms schemes which this paper focuses on finding a simple and easy to follow algorithm for its computation. one famous multiwavelet filter used here is the ghm filter proposed by geronimo, hardian, and massopust. the ghm basis offers a combination of orthogonality, symmetry, and compact support, which can not be achieved by any scalar wavelet basis. using a computer program for the proposed method, an example test on lena image is verified which shows image properties after a single level decomposition and the reconstructed image after reconstruction. keyword: discrete multiwavelete transform (dmwt), inverse discrete multiwavelete transform (idmwt), critical-sampling, schema of processing. 1. introduction as multiwavelet filter banks require a vector-valued input signal, there are a number of ways to produce such a signal from 2-d signal image data. perhaps the most obvious method is to use adjacent rows and columns of the image data [6]. however, this approach does not work well for general multiwavelets and leads to reconstruction artifacts in the lowpass data after coefficient quantization [6]. this problem can be avoided by constructing “constrained” multiwavelets, which possess certain key properties. unfortunately, the extra constraints are somewhat restrictive; image compression tests show that constrained multiwavelets do not perform as well as some other multifilters [2]. another approach is to first split each row or column into two half-length signals, and then use these two half signals as the channel inputs into the multifilter. a naive approach, as strela points out [6], is to simply take the odd samples for one signal and the even samples for the second signal this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ w. a. mahmoud /al-khwarizmi engineering journal ,vol.1, no. 1,pp 26-37 (2005) 27 . 2. multiwavelets theory as in the scalar wavelet case, the theory of multiwvelets is based on the idea of multiresolution analysis (mra), analyzing the signal at different scales or resolutions. the difference is that multiwavelets have several scaling functions. the standard multiresolution has one scaling function (t) [2]. for notational convenience, the set of scaling functions can be written using the vector notation (t)[1(t), 2(t)… r(t)] t ,where (t) is called the multiscaling function. likewise, the multiwavelet function is defined from the set of wavelet functions as (t)[1(t), 2(t)… r(t)] t. when r=1, (t) is called a scalar wavelet, or simply wavelet. while in principle r can be arbitrarily large. the multiwavelets studied to date are primarily for r=2 [7]. the multiwavelet two-scale equations resemble those for scalar wavelets:    k k ktht )2(2)( (1)    k k ktgt )2(2)( (2) note, however, that {hk} and {gk} are matrix filters, i.e., hk and gk are r r matrices for each integer k. the matrix elements in these filters provide more degrees of freedom than a traditional scalar wavelet. these extra degrees of freedom can be used to incorporate useful properties into the multiwavelet filters, such as orthogonality, symmetry, and high order of approximation. the key, then, is to figure out how to make the best use of these extra degrees of freedom. multifilter construction methods are already being developed to exploit them. however, the multi-channel nature of multiwavelets also means that the sub-band structure resulting from passing a signal through a multifilter bank is different. sufficiently different, in fact, so that established quantization methods do not perform as well with multiwavelets as they do with wavelets [2]. one famous multiwavelet filter is the ghm filter proposed by geronimo, hardian, and massopust [3]. the ghm basis offers a combination of orthogonality, symmetry, and compact support, which can not be achieved by any scalar wavelet basis [8]. according to eqs.(1) and (2) the ghm two scaling and wavelet functions satisfy the following two-scale dilation equations:                k k kt kt h t t )2( )2( 2 )( )( 2 1 2 1     (3)                k k kt kt g t t )2( )2( 2 )( )( 2 1 2 1     (4) where hk for ghm system are four scaling matrices h0, h1, h2, and h3, [9], , 2 1 20 9 0 25 3 , 210 3 20 1 5 4 25 3 10                            hh                             0 20 1 00 , 210 3 20 9 00 32 hh also, gk for ghm system are four wavelet matrices g0, g1, g2, and g3, [9],                              0 210 9 2 1 20 9 , 10 3 210 1 210 3 20 1 10 gg                             0 210 1 0 20 1 , 10 3 210 9 210 3 20 9 32 gg there are four remarkable properties of the geronomo-hardin-massopust scaling functions, as follows [2]:  they each have short support (the intervals [0,1] and [0,2]).  both scaling functions are symmetric, and the wavelets form a symmetric/antisymmetric pair.  all integers translates of the scaling functions are orthogonal.  the system has second order of approximation. while the very first multiwavelet literature goes back further [7], some of the earliest developed multiresolution theory of multiwavelets can be found in a paper by goodman et al. [10]. strela's in his ph.d. thesis [6] extends the theory of multiwavelets even further and presents it in terms of pr multifilter banks in both the time and frequency domains. the 2×2 matrix filters in our multiwavelet filter bank require vector inputs. thus, a 1-d input signal must be transformed (5) (6) this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ w. a. mahmoud /al-khwarizmi engineering journal ,vol.1, no. 1,pp 26-37 (2005) 28 into two 1-d signals. this transformation is called pre-processing. for some multiwavelets, the pre-processing must be accompanied by an appropriate pre-filtering operation that depends on the spectral characteristics of the multiwavelet filters [11]. however, some multiwavelets obviate the pre-filtering (and the pre-processing) operation due to certain desirable properties of their basis functions; these multiwavelets are called balanced multiwavelets [1]. 3. a critically-sampled scheme of preprocessing: approximation-based preprocessing a different way to get input rows for the multiwavelet filter bank is to preprocess the given scalar signal f [n]. for data compression, where one is trying to find compact transform representations for a dataset, it is imperative to find critically sampled multiwavelet transforms schemes [3]. a preprocessing algorithm based on the approximation properties of the continuous-time multiwavelets, which yields a critically sampled signal representation suggested by j. geronimo and developed by v. strela, p. niels, and g. strang [2]. let the continuous-time function f (t) belong to the scale-limited subspace v0 generated by translates of the ghm scaling functions. this means that f (t) is a linear combination of translates of those functions [2]:   n nn ntvntvtf )()()( 2 )0( ,21 )0( ,1  (7) suppose that the input sequence f [n] contains samples of f (t) at half-integers: ).2/1(]12[ ),(]2[  nfnfnfnf (8) 1(t) vanishes at all integer points. 2(t) is nonzero only at the integer 1. sampling the eq. (8) at integers and half-integers gives: )0( ,22 )0( ,11 )0( 1,22 )0( 1,22 )2/1()2/1()2/3(]12[ )1(]2[ nnn n vvvnf vnf       the coefficients )0( ,2 )0( ,1 , nn vv can be easily found from (9): )1( ]22[ )2/1()1( ]2[)2/3(]22[)2/1(]12[)1( 2 )0( ,2 12 222)0( ,1        nf v nfnfnf v n n taking into account the symmetry of 2(t), )1( ]22[ )2/1()1( ])2[]22[)(2/1(]12[)1( 2 )0( ,2 12 22)0( ,1        nf v nfnfnf v n n the eq. (11) give a natural way to get two input rows )0( ,2 )0( ,1 , nn vv starting from a given signal f [n]. to synthesize the signal on output, invert eq.(11) and recover eq.(9) [2]. 4. multiwavelets transform computation: basic principles for computing discrete multiwavelet transform, a transform matrix can be written as follows [12]:                 ..................... ...00 ...00 ...00 ...00 3210 3210 3210 3210 gggg hhhh gggg hhhh where hi and gi are the lowand high-pass filter impulse responses. they are 2-by-2 matrices which can be written as follows:                                 ........................... ........................... ...0000 ...0000 ...0000 ...0000 ............... ............... ............... ............... 1,10,11,10,1 1,00,01,00,0 1,10,11,10,1 1,00,01,00,0 1,10,11,10,1 1,00,01,00,0 1,10,11,10,1 1,00,01,00,0 1100 1100 1100 1100 1100 1100 1100 1100 gggg gggg hhhh hhhh gggg gggg hhhh hhhh by examining the transform matrices of the daub4 scalar wavelet [13] and the corresponding one of multiwavelets as shown in (12), one can see that in the multiwavelets transform domain there are first and second lowpass coefficients followed by first and second high pass filter coefficients rather than one lowpass coefficient followed by one highpass coefficient. therefore, if we separate these four coefficients, there are four subbands in the transform domain [14]. (9) (10) (11) (13) (12) this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ w. a. mahmoud /al-khwarizmi engineering journal ,vol.1, no. 1,pp 26-37 (2005) 29 5. a general procedure for computing dmwt using a critically-sampled scheme of preprocessing a general procedure can be made for computing a single-level 2-d discrete multiwavelets transform using ghm four multifilters and using a critically-sampled scheme of preprocessing (approximation-based scheme of preprocessing) described in sec.3. by using a critically-sampled scheme of preprocessing (approximation-based scheme of preprocessing), the dmwt matrix has the same dimensions of the input which should be a square matrix nn where n must be power of 2. transformation matrix dimensions which should be equal to image dimensions after preprocessing will be nn for a critical-sampled scheme of preprocessing. there are two orders of approximation types of critically-sampled preprocessing 1st order and 2nd order approximations. for the eq.(10) and using ghm scaling function graph (fig. 1a), values for 1(1/2), 2(1/2), 2(1) and 2(3/2) should be found for first order approximation. for any nn image matrix and using the eq. (10), 1st order approximation-based preprocessing can be summarized as follows where every two rows generate two new rows: afor any odd row, row])-evenious(3/2)[prevrow]-evennext )[2/1( row]-oddsame)[1(( )2/1()1( 1 row-oddnew 22 2 12      (14) b-for any even-row, )1( row-evensame row-evennew 2  (15) it can be seen from fig. 1a that the values of 1(t) and 2(t) are non-zero for t values of [0, 2]. since these functions are generated from a 256 sample then: 1. 1(1/2) = the 64th value in the iterated vector of 1, 2. 2(1/2) = the 64th value in the iterated vector of 2 = 2(3/2), 3. 2(1) = the 128th value in the iterated vector of 2. substituting values of 1(1/2), 2(1) and 2(1/2) in eqs.(14) and (15) for 1st order approximation results, row]-even previous)[11086198.0(row]-evennext )[11086198.0( row]-odd same)[373615.0(row-oddnew   (16) row]-evensame)[12(row-evennew  (17) for 2nd order approximation, eqs. (16) and (17) become, row]-even previous)[28/3(row]-evennext )[88/3( row]-oddsame)[28/10(row-oddnew   (18) row]-evensame[row-evennew  (19) it should be noted that when computing the first odd row, the previous even-row in eq. (16) is equals to zero. in the same manner, when computing the last odd row, the next even-row in eq. (16) is equals to zero. the same thing is valid for eq. (18). it is obvious now why the dimension of the resulting matrix after approximation-based preprocessing has the same dimension as before preprocessing. the following procedure for computing dmwt using approximation-based preprocessing is valid for both 1st and 2nd order of approximation with one exception of using eqs.(16) and (17) for 1st order approximation preprocessing step and eqs. (18) and (19) for 2nd order approximations preprocessing step: 1.checking image dimensions: image matrix should be a square matrix, nn matrix, where n must be power of 2. so checking input image dimensions is the first step of the transform procedure. if the image is not a square matrix some operation must be done to the image like resizing the image or adding rows or column of zeros to get a square matrix. 2.constructing a transformation matrix: using the transformation matrix (12) format, an n/2n/2 transformation matrix should be constructed using ghm lowand high-pass filters matrices given in (5) and (6) respectively. after substituting ghm matrix filter coefficients values as given by this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ w. a. mahmoud /al-khwarizmi engineering journal ,vol.1, no. 1,pp 26-37 (2005) 30 (13), an nn transformation matrix results with same dimensions of input image dimensions after preprocessing. 3.preprocessing rows: approximation-based row preprocessing can be computed by applying eqs. (16) and (17) to the oddand even-rows of the input nn matrix respectively for the 1st order approximation preprocessing. for 2nd order approximation preprocessing, eqs. (16) and (17) are replaced with eqs. (18) and (19) for preprocessing oddand even-rows of the input nn matrix respectively. input matrix dimensions after row preprocessing is the same nn. 4. transformation of image rows: i. apply matrix multiplication to the nn constructed transformation matrix by the nn row preprocessed input image matrix. ii. permute the resulting nn matrix rows by arranging the row pairs 1,2 and 5,6 …, n3, n2 after each other at the upper half of the resulting matrix rows, then the row pairs 3,4 and 7,8,…, n1,n below them at the next lower half. 5.preprocess columns: to repeat the same procedure used in preprocessing rows, i. transpose the row transformed nn matrix resulting from step 4. ii. repeat step 3 to the nn matrix (transpose of the row transformed nn matrix) which results in nn column preprocessed matrix. 6.transformation of image columns : transformation of image columns is applied next to nn column preprocessed matrix as follows: i. apply matrix multiplication to the nn constructed transformation matrix by the nn column preprocessed matrix. ii. permute the resulting nn matrix rows by arranging the row pairs 1,2 and 5,6 …, n3, n2 after each other at the upper half of the resulting matrix rows, then the row pairs 3,4 and 7,8,…, n1, n below them at the next lower half. 7.the final transformed matrix: to get the final transformed matrix: i. transpose the resulting matrix from column transformation step. ii. apply coefficients permutation [15] to the resulting transpose matrix. the final dmwt matrix using approximation-based preprocessing has the same dimensions, nn, of the original image matrix. 6. a general example for computing dmwt using a critically-sampled scheme of preprocessing to verify the general procedure for computing single-level dmwt using criticallysampled scheme of preprocessing, let’s take a general 2-d signal, for example any 88 matrix, and apply the following steps: 1. let x be the input 2-d signal,                            7,76,75,74,73,72,71,70,7 7,66,65,64,63,62,61,60,6 7,56,55,54,53,52,51,50,5 7,46,45,44,43,42,41,40,4 7,36,35,34,33,32,31,30,3 7,26,25,24,23,22,21,20,2 7,16,15,14,13,12,11,10,1 7,06,05,04,03,02,01,00,0 xxxxxxxx xxxxxxxx xxxxxxxx xxxxxxxx xxxxxxxx xxxxxxxx xxxxxxxx xxxxxxxx x 2. for an 88 matrix input 2-d signal, x, construct a 44 (n/2n/2) transformation matrix ,w2, using ghm lowand highpass filters,              1032 1032 3210 3210 2 gggg hhhh gggg hhhh w as ghm filters, h’s and g’s, are 22 matrices, the transformation matrix, w2, dimension after substituting filters coefficients values will be 88 (nn) matrix with same dimension of the input matrix after approximation-based preprocessing. (20) (21) this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ w. a. mahmoud /al-khwarizmi engineering journal ,vol.1, no. 1,pp 26-37 (2005) 31 3. apply row preprocessing to the input 2-d matrix, x, using approximation-based preprocessing which results in a matrix, even odd even odd even odd even odd a rows preprocess even odd even odd even odd even odd 7,76,75,74.73,72,71,70,7 7,66,65,64.63,62,61,60,6 7,56,55,54.53,52,51,50,5 7,46,45,44.43,42,41,40,4 7,36,35,34.33,32,31,30,3 7,26,25,24.23,22,21,20,2 7,16,15,14.13,12,11,10,1 7,06,05,04.03,02,01,00,0 7,76,75,74.73,72,71,70,7 7,66,65,64.63,62,61,60,6 7,56,55,54.53,52,51,50,5 7,46,45,44.43,42,41,40,4 7,36,35,34.33,32,31,30,3 7,26,25,24.23,22,21,20,2 7,16,15,14.13,12,11,10,1 7,06,05,04.03,02,01,00,0                                                           aaaaaaaa aaaaaaaa aaaaaaaa aaaaaaaa aaaaaaaa aaaaaaaa aaaaaaaa aaaaaaaa xxxxxxxx xxxxxxxx xxxxxxxx xxxxxxxx xxxxxxxx xxxxxxxx xxxxxxxx xxxxxxxx x i1st order approximation-based preprocessing, any odd row in the approximation preprocessed [a] matrix can be found from its corresponding odd row of [x] matrix with the even row previous and next to it in the [x] matrix. in the same manner any even row in [a] matrix can be found from its corresponding even row of [x] matrix. using eqs.,(16) and (17), this can be done as follows, ])[11086198.0(])[11086198.0( ])[373615.0( row-even previousrow-evennext row-oddsamerow-odd xx xa   ])[12( row-evensamerow-even xa  ii2nd order approximation-based preprocessing, any odd row in the approximation preprocessed [a] matrix can be found from its corresponding odd row of [x] matrix with the even row previous and next to it in the [x] matrix. in the same manner any even row in [a] matrix can be found from its corresponding even row of [x] matrix. using eqs.,(18) and (19), this can be done as follows, ])[28/3(])[28/3( ])[28/10( row-evenpreviousrow-evennext row-oddsamerow-odd xx xa   ][ row-evensamerow-even xa  4. row transformation is performed as follows, i. let, [ z ]= [w2][a] (27) ii. permute [z],                            7,76,75,74,73,72,71,70,7 7,66,65,64,63,62,61,60,6 7,56,55,54,53,52,51,50,5 7,46,45,44,43,42,41,40,4 7,36,35,34,33,32,31,30,3 7,26,25,24,23,22,21,20,2 7,16,15,14,13,12,11,10,1 7,06,05,04,03,02,01,00,0 zzzzzzzz zzzzzzzz zzzzzzzz zzzzzzzz zzzzzzzz zzzxzzzz zzzzzzzz zzzzzzzz z                            7,76,75,74,73,72,71,70,7 7,66,65,64,63,62,61,60,6 7,36,35,34,33,32,31,30,3 7,26,25,24,23,22,21,20,2 7,56,55,54,53,52,51,50,5 7,46,45,44,43,42,41,40,4 7,16,15,14,13,12,11,10,1 7,06,05,04,03,02,01,00,0 zzzzzzzz zzzzzzzz zzzzzzzz zzzzzzzz zzzzzzzz zzzxzzzz zzzzzzzz zzzzzzzz p 5. apply column transformation, i. transpose [p] matrix.                            7,77,67,37,27,57,47,17,0 6,76,66,36,26,56,46,16,0 5,75,65,35,25,55,45,15,0 4,74,64,34,24,54,44,14,0 3,73,63,33,23,53,43,13,0 2,72,62,32,22,52,42,12,0 1,71,61,31,21,51,41,11,0 0,70,60,30,20,50,40,10,0 t zzzzzzzz zzzzzzzz zzzzzzzz zzzzzzzz zzzzzzzz zzzzzzzz zzzzzzzz zzzzzzzz p ii. preprocess [p]t in the same manner of preprocessing described in step 3 (i and ii) above to get [p] matrix. iii. let [b] = [w2][p] (30) iv. permute [b] to get [b] matrix which is 88 matrix also.                            7,7 7,6 7,5 7,4 7,3 7,2 7,1 7,0 6,7 6,6 6,5 6,4 6,3 6,2 6,1 6,0 5,7 5,6 5,5 5,4 5,3 5,2 5,1 5,0 4,7 4,6 4,5 4,4 4,3 4,2 4,1 4,0 3,7 3,6 3,5 3,4 3,3 3,2 3,1 3,0 2,7 2,6 2,5 2,4 2,3 2,2 2,1 2,0 1,7 1,6 1,5 1,4 1,3 1,2 1,1 1,0 0,7 0,6 0,5 0,4 0,3 0,2 0,1 0,0 b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b                            7,7 7,6 7,3 7,2 7,5 7,4 7,1 7,0 6,7 6,6 6,3 6,2 6,5 6,4 6,1 6,0 5,7 5,6 5,3 5,2 5,5 5,4 5,1 5,0 4,7 4,6 4,3 4,2 4,5 4,4 4,1 4,0 3,7 3,6 3,3 3,2 3,5 3,4 3,1 3,0 2,7 2,6 2,3 2,2 2,5 2,4 2,1 2,0 1,7 1,6 1,3 1,2 1,5 1,4 1,1 1,0 0,7 0,6 0,3 0,2 0,5 0,4 0,1 0,0 b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b 6. the final dmwt matrix [y]results from apply the following: i. transpose [b] matrix to get [y] matrix ii. apply coefficients permutation to each of the four basic subbands of matrix [y] to get the final dmwt matrix [y].                        7,76,75,74,73,72,71,70,7 7,66,65,64,63,62,61,60,6 7,56,55,54,53,52,51,50,5 7,46,45,44,43,42,41,40,4 7,36,35,34,33,32,31,30,3 7,26,25,24,23,22,21,20,2 7,16,15,14,13,12,11,10,1 7,06,05,04,03,02,01,00,0 ][ yyyyyyyy yyyyyyyy yyyyyyyy yyyyyyyy yyyyyyyy yyyyyyyy yyyyyyyy yyyyyyyy y (31) (28) permute permute (24) (22) (23) (25) (26) (29) this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ w. a. mahmoud /al-khwarizmi engineering journal ,vol.1, no. 1,pp 26-37 (2005) 32                        7,75,76,74,73,71,72,70,7 7,55,56,54,53,51,52,50,5 7,65,66,64,63,61,62,60,6 7,45,46,44,43,41,42,40,4 7,35,36,34,33,31,32,30,3 7,15,16,14,13,11,12,10,1 7,25,26,24,23,21,22,20,2 7,05,06,04,03,01,02,00,0 ][ yyyyyyyy yyyyyyyy yyyyyyyy yyyyyyyy yyyyyyyy yyyyyyyy yyyyyyyy yyyyyyyy y 7. a computer test two general computer programs computing a single-level dmwt using a critical-sampled scheme of preprocessing (1st and 2nd order approximation) are written using matlab v.6.5 for a general nn 2-d signal (or image). an example test is applied to “lena” image by using this computer program of the proposed method for computing discrete multiwavelets transform using a critical-sampled scheme of preprocessing and the results are shown in fig.2 and fig.3for the 1st and 2nd order approximations respectively. as shown in both figs.2 and 3, the original “lena” image, fig. 2a, and 3a dimensions are 512512 (nn). after a single-level of multiwavelets decomposition using a criticalsampled scheme of preprocessing, image dimensions will be a matrix of 512512 (nn) as shown in figs. 2b and 3b. the upper-left most, l1l1, subband of 128128 dimension, is zoomed in as in figs. 2c and 3c. 8. a general procedure for computing inverse dmwt using a critically-sampled scheme of postprocessing to reconstruct the original 2-d signal (nn matrix) from the discrete multiwavelets transformed 2-d signal the inverse discrete multiwavelets transform (idmwt) should be used. a general procedure can be followed for computing a single-level 2-d discrete multiwavelets inverse transform using ghm four multifilters and using a critically-sampled scheme of postprocessing (approximation-based scheme of postprocessing). by using a critically-sampled scheme of preprocessing (approximation-based scheme of preprocessing), the dmwt matrix has the same dimensions of the input which should be a square matrix nn where n must be power of 2. so, to reconstruct the original nn matrix, a reconstruction matrix, which is the inverse (or transpose) of transformation matrix given (12), dimensions should be equal to critical-sampled preprocessed dmwt nn matrix dimensions. as there are two orders of approximation types of critically-sampled preprocessing, 1st order and 2nd order approximations, there are correspondingly two types of critically-sampled postprocessing methods that should be followed; one for each order of approximations. to compute a single-level 2-d inverse discrete multiwavelets transform using critically-sampled scheme of postprocessing, the next steps should be followed: 1. coefficients shuffling [15], which is applied to the dmwt nn matrix four basic subbands individually. for each subband, coefficients shuffling, shuffles columns first then rows. 2. column reconstruction, i. transpose the coefficients shuffled nn matrix. ii. apply shuffling by arranging the row pairs 1,2 and 3,4,…,(n/2)1,n/2 of the coefficients shuffled nn matrix transpose to be the row pairs 1,2 and 5,6,…, n3, n2 of the resulting matrix and arranging the row pairs (n/2)+1,(n/2)+2 and (n/2)+3,(n/2)+4,…, n1,n of the coefficients shuffled 2n2n matrix transpose to be the row pairs 3,4 and 7,8,…, n1, n of the resulting matrix. iii. multiply an nn reconstruction matrix (nn transformation matrix (12) transpose) with the resulting nn shuffled matrix from ii. 3. postprocessing, a critical-sampled scheme of postprocessing can be computed as follows: i. 1st order approximation postprocessing: can be computed by applying the equations: coff. perm. (32) this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ w. a. mahmoud /al-khwarizmi engineering journal ,vol.1, no. 1,pp 26-37 (2005) 33 )373615.0(/ row]]-even previous)[11086198.0(row]-evennext [ )11086198.0(row]-odd same[[row-odd   (33) )12(row]/-evensame[row-even  (34) to the oddand even-rows of the column reconstructed nn matrix respectively. ii. 2nd order approximation postprocessing: can be computed by applying the equations: )28/10(row]]/-even previous)[28/3( row]-evennext )[88/3(row]-oddsame[[row-odd   (35) row]-evensame[row-even  (36) to the oddand even-rows of the column reconstructed nn matrix respectively. 4. row reconstruction i. transpose the postprocessed nn resultant matrix. ii. apply shuffling by arranging the row pairs 1,2 and 3,4,…,(n/2)1,n/2 of the nn postprocessed resultant matrix transpose to be the row pairs 1,2 and 5,6,…, n3, n2 of the resulting matrix and arranging the row pairs (n/2)+1, (n/2)+2 and (n/2)+3, (n/2)+4,…, n1, n of the nn postprocessed resultant matrix transpose to be the row pairs 3,4 and 7,8,…, n1, n of the resulting matrix. iii. multiply a nn reconstruction matrix (nn transformation matrix (12) transpose) with the resulting nn shuffled matrix from ii 5. postprocessing, a critical-sampled scheme of postprocessing can be done by the same process of step 3 above which results in the nn original reconstructed 2-d signal matrix. 9. a general example for computing inverse dmwt using a critically-sampled scheme of postprocessing to verify idmwt procedure in the previous section, apply it to the 88 matrix, [y], given in (32) as the nn critically-sampled preprocessed dmwt matrix to reconstruct 88 matrix, [x], given in (20) as the nn original 2d signal matrix as follows: 1. apply coefficients shuffling to each subband of [y] matrix of (32) which results in [y] matrix of (32). 2. column reconstruction applied now to [y] matrix of (32), i. transpose [y] to get [b] matrix given in (31). ii. apply shuffling to [b] matrix given in (31) to have [b] matrix of (31) as a result of shuffling. iii. using [w2] matrix given in (21), [p] = [w2] t [b] (37) 3. postprocessing [p] matrix results in [p]t given in (29). 4. row reconstruction applied on [p] matrix, i. transpose [p] t matrix of (29) which results in [p] matrix of (28). ii. apply shuffling to [p] matrix given in (28) to get [z] matrix of (28) as a result of shuffling. iii. using [w2] matrix given in (21), [a] = [w2] t [z] (38) [a] is given in (22). 5. critically-sampled postprocessing [a] matrix results in [x] of (20) which is the original reconstructed 2-d signal. 10. a computer test two general computer programs computing a single-level idmwt using a critical-sampled scheme of postprocessing (1st and 2nd postprocessing) are written using matlab v.6.5 for a general 2n2n 2-d decomposed image. an example test is applied to the decomposed lena image shown in figs.2b and 3b to reconstruct the original “lena” image by using those computer programs of the proposed this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ w. a. mahmoud /al-khwarizmi engineering journal ,vol.1, no. 1,pp 26-37 (2005) 34 method of computing inverse discrete multiwavelets transform using 1st and 2nd order approximations postprocessing respectively and the results is shown in fig.4. 11. conclusion multiwavelets filter banks require a vector-valued input signal. this is another issue which is addressed when multiwavelets are used in the transform process. a scalar-valued input signal must somehow be converted into a suitable vector-valued signal. this conversion is called preprocessing. the most obvious way to get two input rows from a given signal is to repeat the signal using repeated row preprocessing (over-sampled scheme of preprocessing). an approximationbased preprocessing algorithms have been also used as a critical-sampled scheme of preprocessing the signal. using a critical-sampled scheme of preprocessing (approximation-based preprocessing) ensures the same original image dimensions while using an over-sampled scheme of preprocessing (repeated row preprocessing) introduces an oversampling of data by a factor of 2 which doubles the original image dimensions. in the same time, the upper-left most subband (l1l1) of the decomposed image using criticalsampling scheme of preprocessing, which usually the 2nd, 3rd,… levels of decompositions are applied to it, has quarter dimensions of the original while the upper-left most subband (l1l1) of the decomposed image using an over-sampled scheme of preprocessing has half dimensions of the original. so that critical-sampled representation of the signal minimizes the redundancy for data compression applications. it should be mentioned here also that discrete multiwavelets transform computation algorithm using a critical-sampled scheme of preprocessing (approximation-based preprocessing) should be applied to a matrix with a size at least equal to 88. also matrix approximation scheme is the scheme that is chosen for multiwavelet compression. such a scheme will keep the same size of the matrix to be transformed after preprocessing. (b) (a) fig. 1: ghm pair of , (a) scaling functions, (b) multiwavelets. fig.2: lena image, (a) original, (b) after singlelevel of dmwt using a critical-sampled scheme of preprocessing(1st order approx.) and, (c) zoomed in upper-left most, l1l1 , subband of (b). (a) (b) (c) this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ w. a. mahmoud /al-khwarizmi engineering journal ,vol.1, no. 1,pp 26-37 (2005) 35 (a) (b) fig.3: lena image, (a) original, (b) after single-level of dmwt using a critical-sampled scheme of prepro.(1st order approx.) and, (c) after single-level of dmwt using a critical-sampled scheme of prepro. (2nd order approx.) (b) fig.4: (a) reconstructed lena image using idmwt and 1st order approx. postprocessing, (b) reconstructed lena image using idmwt and 2nd order approx. postprocessing, and (c)original lena image (a) (c) (c) this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ w. a. mahmoud /al-khwarizmi engineering journal ,vol.1, no. 1,pp 26-37 (2005) 36 12. references 1. michael b. martin, applications of multiwavelets to image compression, m.sc. thesis in electrical engineering, virginia polytechnic institute and state university(virginia tech),blacksburg, virginia, june, 1999. 2. vasily strela, peter niels heller, gilbert strang, pankaj topiwala, and christopher heil, the application of multiwavelet filterbank to image processing, ieee transactions on image processing, vol. 8, no. 4, pp(548-563),april 1999. 3. j. geronimo, d. hardin, and p. r. massopust, fractal function and wavelet expansions based on several functions, j. approx. theory, vol.78, pp(373-401), 1994). 4. yun q. shi, huifang sun: image and video compression for multimedia engineering, fundamentals, algorithms, and standards, crc press llc, 2000. 5. panrong xiao: image compression by wavelet transform, m.sc. thesis, dept. of computer and information science, east tennessee state university, august, 2001. 6. vasily strela, multiwavelets: theory and applications, ph.d. thesis, massachusetts institute of technology, 1996. 7. michael b. martin and amy e. bell, member, ieee, new image compression techniques using multiwavelets and multiwavelet packets, ieee transactions on image processing, vol. 10, no. 4, april 2001. 8. daubechies, ten lectures on wavelets, pp.(251-254), siam, 1992. 9. v. strela and a. t. walden, orthogonal and biorthogonal multiwavelets for signal denoising and image compression, proc. spie, 3391:96-107, 1998. 10. t. n. t. goodman and s. l. lee, wavelets of multiplicity r, trans. of the amer. math. society, 342(1):307-324, march 1994. 11. p. p. vaidyanathan, multirate systems and filter banks, prentice hall, englewood cli_s, nj, first edition, 1993. 12. s. dunn: digital color, http://davis.wpi.edu/~matt/courses/color. 13. k. sayood, and morgan kaufmann, introduction to data compression, lecture 01-2003 spring text book, second edition, academic press, http:// www.cs.sunysb.edu/~amohr/cse391/200 3-spring/ lectures/cse391-lecture01.pdf. 14. j. ziv, a. lempel: a universal algorithm for sequential data, compression, ieee trans. inform. theory, 1977, vol. 23, no. 3, pp. 337343. 15. w. a. mahmoud, z. j. m. saleh, and n. k. wafi, a simple and easy to verify algorithm for computing ghm multiwavelets transform and inverse transform using an over-sampled scheme of preprocessing and postprocessing respectively, journal of engineering, college of engineering, university of baghdad, accepted for publication, een/68, 2004. !! !! !! !! !!this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ w. a. mahmoud /al-khwarizmi engineering journal ,vol.1, no. 1,pp 26-37 (2005) 37 !! !! !! !! œ! ƒ! ! !œ!!!!!! !! ! ƒ! š!!!! ! œ! !œ!ž !! ! !œ!!œ!! ! œ!! œƒ!! !!!! ! š!œ!! !! !! !œ!¾ƒ!! !!œ!! œ! š!!! ! !! ! œ!! !!! !œ!! ! !! œ!ƒ! !!!! œ!!! !! !! !! !! !!!! ! š! !! ƒ! œ!!ƒ!!!!!!!!!!!!!!!!!!!! š! !¾! ! !!œƒ!!š!œ!!!!!!!!!!!!!!!! !!!! !! !¾ƒ!! !! œ! !!!! !! !œ!!! ! ! !!!! ! !!! !!!!! !!! ! !!! !!!! !!!!!!!! !!!ÿ! !š!! ! !! !! ! !ÿ! !!!! ! !!! !!! !!! ! ! ! !! ! !!!! ! !!! !! !!!!!!!! !!!ÿ! !š!! ! ! ! ! !œ!!! !!!!!!!!!!! œ! !! œ! ! ! ! ! œ!! œ!! ¾œ! !œ! ! œƒ! !! !¾! ! œ! ¾ƒ! š!!œ! ! !! !ƒ! ! !œ! ! ! ƒ! ! !œ! ¾ƒ! š!! ! ! œ! ƒ! ! !œ! !!!!! ! ! ! ƒ! š!! ! ƒ!! ! œ!! !! œ! ƒœ!! ƒ!!!! ! œ!! ! œ! ! œ!! œƒ! !! !œ! !! ! ! !!ƒ!! ! ƒ!!!! !!¾ƒ! š!! ! ! !! œ! ! œ!šƒ! ! ƒš! ! !! !šœ! ! ! ! ! ! ! ! ! ! !!!! ! ƒ! œƒ!! !œ! !! œ! ! œ!! œ ! ! ž! œ! ! !œ! ! œ! ƒ! ! !œ!dmwt! !ž! œ! ! ! ! ! ž! ! ! œ!! ¾œ! !œ! ! œƒ! !! ! ! !œ!! !! !œ! !ƒ! !!!! ! !ƒ! ! ! !œ! ƒœ! ! ! ! !!! ! •! ƒ!! !!! œƒ! ! ! ž! œ! ! !! ! ž! !! !!! ƒ! œƒ!! !œ!!!º !!! ƒ! ! !!œ!! !!! ƒ!! !!œ!!!! !! ! !!!!! !!! ! !œ!! ! !œ!! !œ!!! !! !!š! ! ! !! ! œ! ! !!!!!!!!!š! ! ! !œ!œ! ! ! !!!! !! !! !! ƒ!ž š! !œ!!!!! œ! ! œ!! œ! !!!! !!! ! !ƒ!! !ƒ!! !!! œ! œ!! ! !! œƒ! !! !œ!! ! !! ƒž! !! !! !¾! ! š!!!! !ƒ! ! !š! ! !!! œ!!! ! !! !!œ ! ƒ!œ! ! œ! !!œ! ! ! !œ!! !œ! ¾œ! !!! œ!! ! !! !œ! ! ! !!! ! !!! !! !! ¾! œ!!œ! ! œ!!! !! ! ƒ!œ! œ! ! ! !! !! ¾! !!! ! !ƒ! ! !œ!ï! !!! ! !! !!œ! ! !!!œ! !!! ! ! ! š!œ!! ! !! !! !œ!! ! ƒ!! !!œ!!œ! œƒ!!! !!œ!! œ!œ! š!! !œ!! œ!š!!¾œš!! !!! !! !! ! ! !•! ƒ!! ! œ!š! ! ! !œ!! ! ! !! œ!! !!œ! !!!œ!!! ƒ!œ! ! œ!! !! š!ƒ!!! ž!œ!! œ!!! œ! ! !!! !œ!! ƒ!! !!! œ!ƒ!! !!! ž!!•! !!!! ! !! !!! œ!!! !!œ! !!œ! !!œƒ! !! !!! ƒ!! !œ! !!! ! ! ! ! !œ!! ƒ! !! !! ž!œ!! !œ! œ!! ! ! ! !œ! ! œ! !!!! ! !!! ! !œ! ! ! !œ!! !œ! !! ! !! ž! ! !!! ! !!! ! !œ! ! ! !œ!! !œ! ! !ƒ! ! ! ! œ!! ƒ! !!!œ!! !!! ! ! !! ! ! !ƒ! ! ! ! ! ! ! ! ! œ! !! œ! !! ! ! ! ! ! œ! !šœ!! !! ! ! !! !! ! !œ!! œ!œ! š!œ!! ! !¾!!ƒ! ! !!œ! ! ! ! š! ! !! !! !¾ƒ!! !!! ! š!!œ!œ!! ! ! !!œ! !œ! š!!dmwt! !œ!! !œ! œ!œ! !!œ! !! ! ! ! œƒ! !! !œ!! ƒ!! !!! œ!œ! š!! !!! !! ž!œ!¾ƒ!!!!! !! this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ د محمد واميل al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 7, no.4, pp 61 -75 (2011) simulation of oxygen mass transfer in an internal loop airlift reactor with axial dispersion model mohammed a. atiya* ameel mohammed rahman** aseel abd al-jabbar** *ministry of higher education and scientific research/ research and development department ** department of biochemical engineering/ al-khwarizmi college of engineering/university of baghdad (received 7 february 2011; accepted 18 october 2011) abstract the effect of superficial gas velocity within the range 0.01-0.164 m/s on gas holdup (overall, riser and down comer), volumetric oxygen mass transfer coefficient, liquid circulation velocity was studied in an internal loop concentric tubes airlift reactor (working volume 45 liters). it was shown that as the usg increases the gas holdup and also the liquid circulation velocity increase. also it was found that increasing superficial gas velocity lead to increase the interfacial area that increases the overall oxygen mass transfer coefficient. the hydrodynamic experimental results were modeled with the available equations in the literature. the predicted data gave an acceptable accuracy with the empirical data. the final empirical and predicted data were adopted in a mathematical model for oxygen mass transfer to predict the oxygen profile along the reactor. the predicted results have been validated with the experimental results. the simulated results based on the dispersion model for the riser and down comer and the perfect mixed model for the gas-liquid separator, agreed well with the experimental results over the studied range of operating conditions. keywords: airlift bioreactor, reactor, dissolved oxygen; modeling, axial dispersion model, hydrodynamics, mixing, internal loop, liquid circulation velocity, gas holdup. 1. introduction airlift reactors (alrs) are pneumatic contactors and have attracted considerable attention compared to the continuous stirred tank reactor (cstr) due to their simple construction without internal moving parts, high heat and mass transfer capacity, and excellent mixing properties with low power requirements (guillermo et al., 2009; yuwei, et al., 2008; chisiti, 1989); and their effectiveness has been proven in numerous applications, including synthesis of methanol or dimethyl ether from synthetic gas, coal liquefaction, fischer–tropsch synthesis, petroleum refining, and fermentation systems (peter et al., 2010; giovannettonea, et al., 2009; tongwang et al., 2005; chisti, 1989). the hydrodynamic behavior of the gas and liquid flows in airlift reactors is very complicated. the convective and diffusive transfer with volume reactions are realized simultaneously. the convective transfer is a result of a laminar or turbulent (large-scale pulsations) flows. the diffusive transfer is molecular or turbulent (smallscale pulsations). the volume reactions are mass sources as a result of chemical reaction and interphase mass transfer (chisti, 1989). an accurate description of the performance of airlift bioreactors is still difficult. one of the most important factors in the operation of airlift reactors is the rate of gas-liquid mass transfer which control the uptake and removal of low soluble components such as oxygen and carbon dioxide. a number of empirical correlations for estimating mass transfer in terms of the overall mass transfer coefficient (kla) were available according to various geometrical and operational conditions of the contactor. this parameter is important for the construction of mathematical mass transfer model for the (alr) as it provides information on the rate at which mass transfer takes place through the mohammed a. atiya al-khwarizmi engineering journal, vol. 7, no. 4, pp 61-75 (2011) 62 gas-liquid interface. several mathematical models for mass transfer based on material conservation principals in the alr have been proposed. these models considered the alr to be composed of several regions for which mixing characteristics were different. for example, fields and slater (1983) showed that, in a concentric tube alr, gas-liquid separator behaved almost like a perfectly mixed model, whereas the riser and downcomer could be represented by axial dispersion models. verlaan (1989) and merchuk and yunger (1990) used the plug flow model to represent the flow in the riser and downcomer. these mixing characteristic models were then applied to evaluate mass transfer characteristics in alr. andré et al. (1983) used a tank-in-series model for both riser and downcomer to incorporate backmixing, and the gas separator was considered as a well-mixed region in describing mass transfer in external loop alr. the same attempts were adopted by tongwang et al., (2005). dhaouadi et al. (2001) proposed the model where gas and liquid flow in riser and downcomer were considered as plug flow but the mixed zones at the separator and the bottom junction were neglected. these literatures showed that oxygen concentration profiles in alr could be predicted by mathematical models based on material conservation equations. in general, the plug flow with dispersion is best to describe the behavior of liquid and gas flow in riser, whereas the cstr model is best to describe the behavior of liquid and gas flow in gas-liquid separator. in the downcomer, there are differences between external loop and internal loop alr. in external loop alrs, the interaction between gas and liquid in the downcomer may be neglected without interrupting the predicting capability of the model because there exists very little, if not none, amount of gas in this section. however, this situation is unlikely for internal loop alrs where a large fraction of gas holdup is usually present in the various sections of the system. mathematical models for the internal loop alr were usually more complicated and subjected to parameter fittings with experimental data. this limits the use of the models to some specific experimental ranges. this work intends to investigate the accuracy of the mass transfer model developed for the internal loop alr by assuming the alr to comprise three interconnecting sections where the interactions between gas and liquid in each section is taken into consideration. to ensure the general use of the model, parameter estimations are performed using independent experiments, and in many cases, they are obtained from other independent sources. 2. mathematical model development in the present work the mathematical model for the proposed alr is developed by dividing the whole reactor into three main regions: riser, downcomer and gas separator which is located at the top of the reactor. a mixture of gas and liquid moves from the riser to gas separator. a large fraction of gas bubbles disengages from the system here whilst liquid and the remaining portion of gas move further to the downcomer. in this last section, no gas supply is provided and the fluid content moves downwards and reenters the riser at the bottom of the column together with the inlet gas. in this proposed mathematical model for the present system, each part of the alr is considered separately as illustrated in fig.1. the riser and downcomer are represented by the dispersion model with the exchange of oxygen between gas and liquid phases in each volume element. no liquid is added or removed from the system, whereas gas enters the system only at the bottom section of the riser and leaves the contactor at the gas separator. the behavior of the gas separator is assumed to be well mixed. hence, the overall model is represented by a series of various types of reactors, i.e. dispersion stirred tank-dispersion. the following assumptions are considered to simplify the development of this model (chisti, 1989; znad et al., 2004): 1. ideal gas behavior in the system. 2. isothermal conditions. 3. the effect of hydrostatic head on solubility of oxygen is negligible (for small-scale systems). 4. the overall oxygen volumetric mass transfer coefficient is uniform for all regions in the reactor. 5. the gas holdup is uniform within each individual region. 6. the hydrodynamic parameters, e.g. gas holdups, liquid circulation flowrate, are not a function of time and space. 7. there is no radial effect in the alr. 8. oxygen is sparingly soluble in water and henry’s law can be applied to explain the solubility of oxygen in the contactor. mohammed a. atiya al-khwarizmi engineering journal, vol. 7, no. 4, pp 61-75 (2011) 63 fig. 1. schematic diagram representing the internal loop in the present alr. 3. material balances in alr regions the proposed model provides simultaneous differential equations which are material balances of the dissolved oxygen. the unsteady state material balance of dissolved oxygen can be written as follows: 3.1. riser section for gas phase oxygen concentration: at rr lz <<0 : ( ) tzo h tzo k z tzo d z tzo v t tzo rlr rgr la gr gr r rrg gr r rrg gr rrg         − − − ∂ ∂ + ∂ ∂ −= ∂ ∂ ),( ),(1 ),(),(),( 2 2 ε ε …(1) for liquid phase oxygen concentration: tzo h tzo k z tzo d z tzo v t tzo rlr rgr la r rrl gr r rrl gr rrl       − + ∂ ∂ + ∂ ∂ −= ∂ ∂ ),( ),( ),(),(),( 2 2 …(2) 3.2. downcomer section for gas phase oxygen concentration: at dd lz <<0 : ( ) tzo h tzo k z tzo d z tzo v t tzo dld dgd la gd gd d ddg gd d ddg gd ddg       − − − ∂ ∂ + ∂ ∂ −= ∂ ∂ ),( ),(1 ),(),(),( 2 2 ε ε …(3) for liquid phase oxygen concentration in the downcomer: tzo h tzo k z tzo d z tzo v t tzo dld dgd la d ddl gd d ddl gd ddl         −+ ∂ ∂ + ∂ ∂ −= ∂ ∂ ),( ),(),( ),(),( 2 2 …(4) where h: is the henry's law constant. 3.3. gas separator section for the gas oxygen concentration: ( ) ( ) o h o k v oqzovalzova t o lt gt la gt gt tgt gtoutgdgdgddgdrrgrgrrgrgt       −         − − −=−= = ∂ ∂ ) 1 0 , ε ε ε εε …(5) for the liquid oxygen concentration: ( ) ( ) ( ) ( ) ( ) o h o k v zovalzova t o lt gt la tgt dldlddgdrrlrlrrgrlt       − + − =−−=− = ∂ ∂ ) 1 011 ε εε …(6) table 1 lists the initial and boundary conditions which are used to solve these equations. r is e r d o w n co m e r n=1 n=٢ n=n-1 n=n m=1 m=2 m=m-1 m=m gas liquid separator gas out gas in mohammed a. atiya al-khwarizmi engineering journal, vol. 7, no. 4, pp 61-75 (2011) 64 table 1, initial and boundary conditions for each section of the present alr . riser section i.c. gas ( ) 00,0 ==≤≤ tlzo rrgr b.c.1 ( )0,0 >= tzo rgr = ( )         +>= rgr ingingrgddgd av oqtzoav ,,0,0 b.c.2 /s)(m 3 , flowrategasinletq ing = ( ) ( )00, >=>= totlzo gtrrgr i.c. liquid ( ) 00,0 ==≤≤ tlzo rrlr b.c.1 ( ) ( )0,0,0 >==>= tlzotzo ddldrlr b.c.2 ( ) ( )00, >=>= totlzo ltrrlr downcomer section i.c. gas ( ) 00,0 ==≤≤ tlzo ddgd b.c. ( ) ( )00,0 >=>= totzo gtdgd i.c. liquid ( ) 00,0 ==≤≤ tlzo ddld b.c. ( ) ( )00,0 >=>= totzo ltdld gas separator section i.c. gas ( ) 00 ==togt liquid ( ) 00 ==tolt i.c.: initial condition b.c.: boundary condition 4. hydrodynamic and gas-liquid mass transfer correlations hydrodynamic behavior is essential for the understanding of the phenomena taking place in alr. due to their strong influence on mass transfer performance, they have received considerable attention from most investigators. hydrodynamic parameters of interest in design are the overall gas holdup, the gas holdups in the riser and in the downcomer, the magnitude of the induced liquid circulation and the liquid phase dispersion coefficients in various regions of the reactor. 4.1. gas holdup correlations the volume fraction of gas (or gas holdup) is an essential parameter for the design of airlift contactors. due to the configuration of airlift contactors that allow aeration in the riser, gas holdup in riser is usually higher than the downcomer. this difference in gas holdups is the main cause of pressure difference, which creates liquid circulation pattern. the overall gas holdup in term of riser, downcomer and gas separator gas holdups was calculated using the following equation (chisti, 1989; zhonghuo, 2010): aa gdgrdggr ))(/( εεεε −+= …(7) where gε : is overall gas holdup grε : is the riser gas holdup gdε : is the downcomer gas holdup 4.2. gas-liquid mass transfer correlations the rate of mass transfer from gas to liquid phase may be expressed in terms of an overall volumetric mass transfer coefficient, kla based on gas liquid dispersion volume. this coefficient is also an important indicator for comparing the oxygen transfer capabilities of various aerobic bioreactors. the volumetric oxygen transfer coefficient is defined by the following equation (zhonghuo et al., 2010; chisti and young, 1987): cnak ol ∆= / 2 …(8) where 2on is the flux of oxygen transfer between phases, ∆c the concentration driving force between the phases. the gas-liquid interfacial area based on liquid volume or gas-liquid dispersion volume (al or ad, respectively) need to be determined to evaluate mohammed a. atiya al-khwarizmi engineering journal, vol. 7, no. 4, pp 61-75 (2011) 65 overall mass transfer coefficient (kla). the value of al and ad can be evaluated from eq. (9) and eq. (10), respectively (chisti, 1998): )] -(1/[d 6 = a gbgl εε …(9) /d6 = a bgd ε …(10) however, instead of determining kl and a separately, the mass transfer behavior in these systems are usually presented in terms of the overall mass transfer coefficient (kla) which was often determined using empirical correlations reported in literature. 4.3. liquid velocity the liquid circulation in airlift reactors originates from the difference in the bulk densities of the fluids in the riser and the downcomer. the liquid circulates a well defined path: up flow in the riser, downflow in the downcomer. the predicted superficial liquid velocities in the airlift reactor were calculated using the following well known tested equation developed by chisti, (1989): aak gh u gddrb gdgrd lr 5.0 22 ))1/(1()/( )(2         − − = ε εε … ( 1 1 ) where a a k b d b 79.0 40.11       = …(12) the height of the dispersion dh was calculated from the following known equation: h h g l d ε− = 1 …(13) the linear liquid velocity in the riser and downcomer can be calculated from the superficial liquid velocity as follows (chisti, 1989): u v gr lr lr ε− = 1 …(14) ( ) ( ) avav dgdldrgrlr εε −=− 11 …(15) 5. solving the mathematical model the mathematical model provides a set of differential equations for oxygen concentration in the riser, downcomer and gas separator. these equations to be solved simulated simultaneously using finite elements technique in matlab v-2008a software package. figure (2) represent the algorithm for the computer simulation which is used to simulate oxygen concentration for a given reactor geometry and gas flow. fig. 2, algorithm for the computer simulation procedure to simulate oxygen concentration for the present alr geometry and gas flow . 6. experimental work 6.1. airlift reactor the proposed airlift reactor consists of two concentric-tubes with dimensions given in table 2. the volume of the reactor was 45 liter and ad/ar=4.29. the water level in the reactor was 1.1 cm. the tubes were constructed of transparent poly acyclic with the bottom and top plates made of rigid nylon. water manometer was used to measure the pressure drop across the reactor and the distance between the two manometer reading geometrical parameters of alr: a , a , a , output oxygen profile )(τo start given usg calculate gε , grε and gdε calculate kb, ulr, uld, vlr, vld,, vgd,, vgd given ∆z given hd, hl, model equations solved simultaneously using finite elements in matlab v-2008a mass transfer parameters kla end mohammed a. atiya al-khwarizmi engineering journal, vol. 7, no. 4, pp 61-75 (2011) 66 points was 100 cm. air spargers and other pipes were constructed of copper. figure (3) shows the schematic arrangement of the experimental apparatus. table 2, dimensions of a concentric tube airlift reactor . height (cm) diameter (do) (cm) diameter (di) (cm) main column 150 23.6 23.0 draft tube 1.00 10.6 10.0 air was sparged through 8 cm diameter circular sparger, with 24 holes of 1 mm diameter. air flow rates were measured by a two type's rotameters (rota company of qvf type). the first one is used for the low flow rates (max. reading 1 m3/h) and the second one for the higher rate (max. reading 10 m3/h). all experimental runs were carried out at atmospheric pressure and a temperature of 29˚c. a series of experiments were performed by varying the superficial gas velocity (with respect to the cross-sectional area of the riser) over the range of 0.01–0.164 ms−1 to create a characteristic velocity curve of the airlift reactor. fig.3.experimental setup of alr. 8 cm hole1 mm diameter o-ring air distributor 3 1 2 4 5 6 7 8 9 10 1 oxygen probe meter 2 draft tube 3 reactor column 4 reducer 5 gas distributor 6 rotameter 7 valve 8 air compressor 9 interface 10 computer 11 u-tube manometer 12 n2 cylinder 13 n2 gas pressure regulator 14 t-join connector ١٥ liquid level 11 12 7 13 14 6 7 7 1 mohammed a. atiya al-khwarizmi engineering journal, vol. 7, no. 4, pp 61-75 (2011) 67 6.2. measurement of volumetric mass transfer coefficient the overall volumetric mass transfer coefficient, kla, was determined by the dynamic gassing method (bouaifi et al., 2001; chisti, 1989). the dissolved oxygen concentration in the batch liquid phase was measured by means of an oxygen probe inserted horizontally at 0.1 m below the exit of the riser that was connected to a dissolved oxygen-meter type lutron do-5510. the oxygen probe signals were measured using a/d converter and recorder on a pc. in each experimental run, tap water has been first stripped of oxygen by the dynamic gassing method by bubbling n2 gas through the gas sparger. this step will continue till the probe reading becomes zero. after that the nitrogen gas flow was turned off and the flow switched to the air flow with a specific volumetric flow rate using the rotameter then the dissolved oxygen concentration was recorded with respect to time as air is distributed into the alr and until the water became saturated with oxygen. 7. method of calculations 7.1. gas hold-up the total gas holdup was determined by the expansion volume method (chisti, 1989). this method was chosen because it was the simplest to use. the gas holdup was estimated as the percentage increase in volume of the gassed liquid compared with ungassed liquid volume. in this airlift bioreactor the variation of liquid volume can be determined by observing the height of the surface of the ungassed liquid and aerated liquid. the dispersion height was estimated by observing the position of the liquid level on a graduated stainless-steel rod suspended from the vessel top plate. at high gas flow rates the liquid surface become very turbulent, with the level changing erratically, and so a mean dispersion height was estimated (chisti, 1989). because the volume of gas cannot be measured directly, we defined vd (dispersed volume) as the total volume of gas phase plus volume of liquid phase. then v vv d ld g − =ε …(16) ah ah d l g −= 1ε …(17) finally, h h d l g −= 1ε …(18) where: hd dispersed liquid height (cm) and hl liquid height (cm). the downcomer gas holdup was estimated by measuring the pressure difference between the two measuring ports of the column and by using the following equation (chisti, 1989): h z manometer gd ∆ ∆ −= 1ε …(19) where: ∆z: distance of liquid level in manometer, ∆h: distance of liquid level. 7.2. mass transfer coefficient the kla is determined as mentioned in the previous section by using the dynamic method. the investigations of mass transfer characteristics were restricted to oxygen transfer only, and in all investigations, the alr systems were subject to the following assumptions (wongsuchoto, 2002): gas composition is constant. the system is isothermal, and the effect of the dynamics of the dissolved oxygen electrode is negligible. for sparingly soluble gases such as oxygen, the liquid phase volumetric mass transfer coefficient (kla) is nearly equal in value to that of the overall volumetric mass transfer coefficient (kla). a material balance on dissolved oxygen according to the above assumption gives the following equation (wongsuchoto, 2002): ( ) ( ) ooakooak dt do ll −=−= ** …(20) o*: saturation dissolved oxygen concentration. o: dissolved oxygen concentration in liquid phases. integrate eq. (6) with the limits of o = o0 at t = 0 and o = o at t = t results in: ∫∫ = − t l o o dtak oo do 0* )(o …(21) the result of integration is atk oo oo l=      − − )( )( ln * * o …(22) mohammed a. atiya al-khwarizmi engineering journal, vol. 7, no. 4, pp 61-75 (2011) 68 the value of kla is obtained from the slope of the linear regression with         − − )( )( ln * * oo oo o with respect to time (t). 8. results and discussion 8.1. effect of superficial gas velocity on gas holdups the effect of superficial gas velocity on the overall, riser and downcomer gas holdups can be represented in fig. 4. as the superficial gas velocity increases the gas holdups increases. generally, the experimental gas holdup profiles are linear with respect to usg for the overall, riser, and downcomer gas holdups. this means that the slip of relative velocity between the gas and liquid phases does not change with increased gas through put. fig. 4. relationship between overall, riser and downcomer gas holdups and superficial gas velocity of the present alr. the experimental data have been simulated with the following equation (chisti, 1989): u sggi γλε = …(23) where λ and γ are constants, and the final result for overall, and dowcomer holdups can be expressed as: u sgg 799.0643.0=ε …(24) u sggd 728.0428.0=ε …(25) the values of riser gas holdup were estimated using eqn. (7). the simulated gas fraction over predicted empirical data, are compared as shown in fig. 5. it can be concluded that the profile also has a linear form with acceptable accuracy. fig.5. comparison between experimental and predicted overall and downcomer gas holdups at the same superficial gas velocity of the present alr . 8.2. effect of superficial gas velocity on internal liquid circulation liquid velocity in airlift reactors affects the mixing characteristics of fluids, i.e. volumetric mass transfer coefficient, which determines the performance of the reactor. figure (6) shows the experimental results of the effect of usg on linear liquid velocity in the riser and downcomer. it can be observed that an increase in gas velocity effectively implied a large energy input to the system and high liquid velocity was induced both in riser and downcomer. the riser and downcomer liquid velocities were determined from eqn. (14) and the mass conservation equation (15) including the effect of both riser and downcomer gas holdups. all configurations demonstrated the less values of downcomer liquid velocity than riser liquid velocity. it was because, in the present experiment work, the cross sectional of the downcomer area was 4.29 times larger than that of 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 superficial gas velocity, usg (m/s) g as h o ld u p , ε () overall gas holdup downcomer gas holdup riser gas holdup 0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 εcalc (-) ε e xp () overall gas holdups (r=0.994) downcomer gas holdups (r=0.991) mohammed a. atiya al-khwarizmi engineering journal, vol. 7, no. 4, pp 61-75 (2011) 69 the riser. hence, all downcomer liquid velocities were lower than riser liquid velocities based on the continuity equation. fig. 6. relationship between linear liquid riser and downcomer velocities and superficial gas velocity for the present alr. 8.3. effect of superficial gas velocity on the overall oxygen mass transfer coefficient figure 7 shows the normalized oxygen concentration-time experimental data. these data were processed with eqn. (22) and the final results were presented by fig. (8). the value of kla is obtained from the slope of the linear regression with         o) o( )o o( ln * * o with respect to dimensionless time (τ ). the obtained k la values where also plotted versus usg and the relationship between them is illustrated in fig. 9. it can be shown from fig. 9 that the value of kla increases with increasing usg. the smallest quantity of air means the lowest liquid velocity, and the low liquid velocity means that there was a rather low level of gas bubbles in the reactor which reduce the interfacial area of gas for mass transfer in the system. at high gas velocity, the liquid velocity increases which in turn generate finer bubbles, and thus increased gas holdup. the higher gas holdup results in higher interfacial area which increases kla. an attempt has been made to correlate the obtained kla values with the following equation (chisti, 1989): uak sgl β α= …(25) the following empirical equation, best relating the volumetric mass transfer coefficient with the superficial gas velocity: uak sgl 738.0 229.0= …(26) equation (26) was obtained by multiple regression analysis with a correlation coefficient of 0.997. figure 10 shows a comparison between experimental and predicted values of kla. it can be seen that the correlation satisfies the experimental data of the present system. fig. 7. relationship between dimensionless oxygen concentration and dimensionless time at different superficial gas velocity for the present alr . fig.8. logarithmic oxygen concentration vs. dimensionless time of the mathematical model at various usg values . 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18 superficial gas velocity, usg (m/s) l in ea r l iq u id v el o ci ty , ( m /s ) vlr vld 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 dimentionless time (-) d im en si o n le ss o xy g en c o n ce n tr at io n , ( -) usg=0.010 m/s usg=0.020 m/s usg=0.040 m/s usg=0.085 m/s usg=0.120 m/s usg=0.1639 m/s 0 1 2 3 4 5 6 7 8 9 10 11 12 13 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 dimentionless time, (-) -ln [( o * -o ₒ )/( o * -o )] usg=0.010 m/s usg=0.020 m/s usg=0.040 m/s usg=0.085 m/s usg=0.120 m/s usg=0.1639 m/s mohammed a. atiya al-khwarizmi engineering journal, vol. 7, no. 4, pp 61-75 (2011) 70 0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 superficial gas velocity, usg, cm/s k l a , ( s-1 ) fig. 9. relationship between overall volumetric oxygen mass transfer coefficient and superficial gas velocity for the present alr. fig. 10. comparison between experimental and predicted overall volumetric oxygen mass transfer coefficient at the same and superficial gas velocity of the present alr . 8.4. mathematical model parameters determination in order to simplify the solution of the mathematical model differential equations. equation (1) to (6) can be converted into a dimensionless form by introducing the following dimensionless variables and using the initial and boundary conditions in table 2: v atv t t r dld==τ …(28) l z z = …(29) o o o l l l * = …(30) o o o ing g g * , = …(31) riser section for gas phase oxygen concentration: ( ) [ ] zozo tk z o l td z o l tvo rlrrgr gr lagr r rg r gr r rg r gr r rg )()( 1 2 2 2 − − − ∂ ∂ + ∂ ∂ −= ∂ ∂ ε ε τ …(32) for liquid phase oxygen concentration: [ ] zozotk z o l td z o l tvo rlrrgrla r rl r lr r rl r lr r rl )()( 2 2 2 − − ∂ ∂ + ∂ ∂ −= ∂ ∂ τ …(33) downcomer section for gas phase oxygen concentration: ( ) [ ] zozo tk z o l td z o l tvo dlddgd gd lagd d dg d gd d dg d gd d dg )()( 1 2 2 2 − − − ∂ ∂ + ∂ ∂ −= ∂ ∂ ε ε τ …(34) for liquid phase oxygen concentration in the downcomer: [ ] zozotk z o l td z o l tvo dlddgdla d dl d ld d dl d ld d dl )()( 2 2 2 − − ∂ ∂ + ∂ ∂ −= ∂ ∂ τ …(35) gas separator section for the gas oxygen concentration: ( ) ( ) ootko v tq o v tq lzo v tqo ltgtla gt gt gt tgt gd gt tgt outg rrgr tgt gr t gt ) 1 , −         − − −−== ∂ ∂ ε ε ε εετ …(36) for the liquid oxygen concentration: ( ) ( ) ( ) ( ) ( ) ootko v tq o v tq lzo v tqo ltgtlalt tgt ld lt tgt outl rrlr tgt lr t lt ) 1 11 , −− − − − −= − = ∂ ∂ ε εετ …(37) 0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 kla calc (s -1) k l a e xp (s -1 ) r=0.997 mohammed a. atiya al-khwarizmi engineering journal, vol. 7, no. 4, pp 61-75 (2011) 71 table 3, initial and boundary conditions in dimensionless form . riser section i.c. gas ( ) 00,10 ==≤≤ τrgr zo b.c.1 ( )0,0 >= τrgr zo = ( )         +>= rgr ingingrgddgd av oqzoav ,,0,0 τ b.c.2 /s)(m 3 , flowrategasinletq ing = ( ) ( )00,1 >=>= ττ gtrgr ozo i.c. liquid ( ) 00,10 ==≤≤ τrlr zo b.c.1 ( ) ( )0,10,0 >==>= ττ dldrlr zozo b.c.2 ( ) ( )00,1 >=>= ττ lrrlr ozo downcomer section i.c. gas ( ) 00,10 ==≤≤ τdgd zo b.c. ( ) ( )00,0 >=>= ττ gtdgd ozo i.c. liquid ( ) 00,10 ==≤≤ τdld zo b.c. ( ) ( )00,0 >=>= ττ ltdld ozo gas separator section i.c. gas ( ) 00 ==τgto liquid ( ) 00 ==τlto i.c. : initial condition b.c.: boundary condition. the proposed mathematical model supplies a set of partial differential equations for oxygen transfer. the solution of these equations was solved simultaneously with the geometric, mass transfer and hydrodynamic parameters using finite elements in matlab v-2008a software package. the oxygen concentration in liquid phase of the present internal loop airlift reactor was predicted by dispersion model. to predict oxygen concentration in liquid phase, hydrodynamic and mass transfer parameters including gas holdups (εg), liquid velocities (νl), gas velocities (νg), dispersion coefficients (d), geometrical parameters and overall volumetric gas-liquid mass transfer coefficient (kla) had to be known in a prior. table 4 employed the correlations used in the present mathematical model. table 4, empirical hydrodynamic correlations used in the mathematical model. correlations usgg 799.0643.0=ε …(24) usggd 728.0428.0=ε …(25) uak sgl 738.0 229.0= …(26) assuming that gtε = grε other parameters such as the downcomer liquid velocity (νld) were calculated from eqn. (14), while the riser liquid velocity was calculated from the continuity eqn. (15). riser gas velocity grv was calculated from lrv and slip velocity in the riser srv as follows (chisti, 1989): vvv srlrgr += …(37) srv did not vary much with conditions in the alr, and it was assumed here to be constant at 0.25 m/s as it reported by chisti, (1989). downcomer gas velocity gdv was calculated, in a similar fashion, using the continuity equation (chisti, 1989): a qav v gdd inggrrgr gd ε ε ,− = …(38) dgr, dgd, dlr and dld as dispersion coefficients in the gas and liquid phases for both the riser and downcomer remained unknown. the liquid phase dispersion coefficients values, dlr and dld were reported by several investigators and employed in this model directly without manipulation (chisti, 1989, kochbeck and hempel, 1994; merchuk et al., 1998). also, gas phase dispersion coefficients (dgr and dgd) were reported by chisti, (1989) to mohammed a. atiya al-khwarizmi engineering journal, vol. 7, no. 4, pp 61-75 (2011) 72 be 2 5 m2/s for the alr at usg between 0.01-0.1 m/s. in order to verify the sensitivity of the simulation results with the variation of the dispersion coefficients for liquid and gas phases. preliminary simulations were conducted and it was found that the time-oxygen concentration profiles from the various simulations of different values of dispersion coefficients in the range reported in the previous paragraph were not significantly different from each other. this indicated that, within the range of dispersion coefficients reported in literature, there was no meaningful difference in the responding time to reach equilibrium concentration. hence, the values of dlr, dld, dgr, dgd used in all simulations were selected arbitrarily as 0.01, 0.01, 2 and 2 m2/s, respectively. to verify the ability of the model in predicting oxygen mass transfer behavior between gas and liquid phases in the internal loop alr, the simulation results were compared with experimental data. figure 11 illustrates the comparisons between the simulation results and experimental data on liquid phase oxygen concentration in the riser (olr) in the system at different superficial gas velocities (usg). in general, both simulation results and experimental data demonstrated that the oxygen concentration profile reached equilibrium concentration more rapidly with increasing usg. it can be concluded that the predicted model results give a reasonable accuracy when compared with experimental data for the same range of usg. 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 dimentionless time (-) d im en si o n le ss o xy g en c o n ce n tr at io n , ( -) usg=0.010 m/s usg=0.020 m/s usg=0.040 m/s usg=0.085 m/s usg=0.120 m/s usg=0.1639 m/s simulated fig. 11. comparison between experimental and simulated data of oxygen-time profiles in the riser region of the present alr . list of abbreviations, notations and greek letters abbreviations alr airlift reactor a cross-sectional area m2 a specific gas-liquid interfacial area of bubble per volume of reactor m2 m−3 ab cross sectional area for flow under baffle or draft tube m2 o instantaneous oxygen concentration in the liquid kgm−3 o* saturation dissolved oxygen concentration in the liquid kgm−3 oo initial oxygen concentration in the liquid kgm−3 d dispersed phase dg gas phase dispersion coefficient m2s−1 db bubble diameter m g gravitational acceleration ms−2 h henery's law constant hd dispersion height m hl unaerated liquid height m kla overall mass transfer coefficient s-1 l length m lb bottom clearance m n moles of a oxygen gas mol og oxygen concentration in gas phase kgm−3 ogd oxygen concentration in gas phase of the downcomer section kgm−3 ogr oxygen concentration in gas phase of the riser section kgm−3 ol oxygen concentration in liquid phase kgm−3 old oxygen concentration in liquid phase of the downcomer section kgm−3 olr oxygen concentration in liquid phase of the riser section kgm−3 t time s t time s usg superficial gas velocity ms−1 ul superficial liquid velocity ms−1 v volume m3 vg linear gas velocity ms−1 vl linear liquid velocity ms−1 vs slip velocity ms−1 z dimensionless length mohammed a. atiya al-khwarizmi engineering journal, vol. 7, no. 4, pp 61-75 (2011) 73 greek letter ∆c concentration driving force between the two phases kgm−3 ∆h distance of liquid level m ∆z distance of liquid level in a manometer m εg gas holdup εgo overall gas holdup εgd gas holdup in the downcomer section εgr gas holdup in the riser section τ dimensionless time α constant β constant γ constant λ constant 9. conclusions in the present study, oxygen mass transfer could be well described by the proposed mathematical model based on a set of continuity equations. the obtained empirical equations for the gas holdups, overall oxygen mass transfer coefficient gave good results and high accuracy for the present alr. the simulated results based on the obtained empirical equations, the dispersion model for the riser and downcomer and the perfect mixed model for the gas-liquid separator, agreed well with the experimental results over the studied range of operating conditions. 10. acknowledgement this study was supported by a grand provided by the ministry of higher education and scientific research/ research and development department. authors gratefully acknowledge this contribution and supporting. 11. references [1] andré, g., robinson, c.w., and young, m.m., (1983), "new criteria for application of the well-mixed model to gas-liquid mass transfer studies", chem. eng. sci., 38: 18451984. [2] bouaifi, m., hebrard, g., bastoul, d., and roustan, m., (2001), "a comparative study of gas hold-up, bubble size, interfacial area and mass transfer coefficients in stirred gas-liquid reactors and bubble columns", chem. eng. proc., 97-111. [3] camarasa e., l.a.c. meleiro, e. carvalho, a. domingues, r. maciel filho, g. wild, s. poncin, n. midoux, and j. bouillard, (2001), "a complete model for oxidation air-lift reactors", computers and chemical engineering, 25, 577–584. [4] cerri m.o., a.c. badino, (2010), "oxygen transfer in three scales of concentric tube airlift bioreactors", biochemical engineering journal, 51, 40–47. [5] chisti y., (1989), "airlift bioreactors", elsevier applied science, london. [6] chisti, m.y., (1998), "pneumatically agitated bioreactors in industrial and environmental bioprocessing: hydrodynamics", appl. mech. rev. 51: 33-112. [7] chisti, m.y., and young, m.m., (1987), "airlift reactors: characteristics, applications and design considerations", chem. eng. commun., 60: 195-242. [8] dhaouadi, h., poncin, s., midoux, n., and wild, g., (2001), "gas-liquid mass transfer in an airlift reactor—analytical solution and experimental confirmation", chem. eng. proc., 40: 129-133. [9] fields, p.r., and slater, n.k.h., (1983), "tracer dispersion in a laboratory air-lift reactor", chem. eng. sci., 38: 647-653. [10] giovannettonea j.p., e. tsaib, j.s. gulliver, (2009),"gas void ratio and bubble diameter inside a deep airlift reactor", chemical engineering journal, 149, 301–310. [11] guillermo quijano, sergio revah, mariano gutierrez-rojas, luis b. flores-cotera and frederic thalasso, (2009), "oxygen transfer in three-phase airlift and stirred tank reactors using silicone oil as transfer vector", process biochemistry, 44, 619–624. [12] koch beck, b., and hempel, d.c., (1994), "liquid velocity and dispersion coefficient in an airlift reactor with inverse internal loop", chem. eng. technol., 17: 401405. [13] merchuk, j.c., and yunger, r., (1990), "the role of the gas-liquid separator of airlift reactors in the mixing process", chem. eng. sci., 45: 2973-2975. [14] merchuk, j.c., contreras, a., garcia, f., and molina, e., (1998), "studies of mixing in a concentric tube airlift bioreactor with mohammed a. atiya al-khwarizmi engineering journal, vol. 7, no. 4, pp 61-75 (2011) 74 different spargers", chem. eng. sci. 53: 709719. [15] peter m. kilonzo, argyrios margaritis, and m.a. bergougnou, (2010), "hydrodynamic characteristics in an inverse internal-loop airlift-driven fibrous-bed bioreactor", chemical engineering science, 65, 692–707. [16] tongwang zhang, tiefeng wang and jinfu wang, (2005), "mathematical modeling of the residence time distribution in loop reactors", chemical engineering and processing, 44, 1221–1227. [17] verlaan, p., van eija, a.m.m., tramper, j., and van’t riet, k., and luyben, k.ch.a.m., (1989), "estimation of axial dispersion in individual sections of an airlift-loop reactor", chem. eng. sci., 44: 1139-1146. [18] wongsuchoto, p., (2002), "bubble characteristics and liquid circulation in internal loop airlift contractors", ph.d. thesis, faculty of engineering, chulalongkorn university, thailand. [19] yu wei, wang tiefeng, liu malin and wang zhanwen, (2008), "bubble circulation regimes in a multi-stage internal-loop airlift reactor", chemical engineering journal, 142, 301–308. [20] zhonghuo deng, tiefeng wang, nian zhang, and zhanwen wang, (2010), "gas holdup, bubble behavior and mass transfer in a 5m high internal-loop airlift reactor with nonnewtonian fluid", chemical engineering journal, 160, 729–737. [21] znad h., v. bales, and y. kawase, (2004), "modeling and scale up of airlift bioreactor", computers and chemical engineering, 28, 2765–2777. � ا��� � � )2011( 75-61 ، ���4، ا���د ����7 ا���ارز�� ا����� � ا����� اج ���� � 75 ذو /(� ا���. ا��ا-�� ��airlift"%"ة ا+*("ل ا'و%�� $ #� ��"�! ��"ل ��د4! ا�*3*2 ا����ري*�"5 � ا���اج� � **ا� ! � � ا�� "ر **ا� ! ���� ر/�$ *���� � داb<ة ا3451 واa:1@?</ وزارة ا89/0:1 ا1701وا3451 ا01/.* ** 8deا fghij1اf9b79klا f9b79.9m1/ -nارز@o1ا pghij1ا f9/q /ادhrs f0n7t �ا��6 ، ivn70n ا7vg:hل )ev/[ 7v\)overall, riser and downcomer ا7vr1ز اdv/0.1 /م ٠.١٦٤-٠.٠١[.v^ دراf[>vg >9\7v] fvg ا7vr1ز اz1<اw.vx fv9y اhv.1ى hvi[ sk@v1 ز?7vدة v:1 . f[>vg< ٤٥اw9s@v5hl اw?qvq>.:.1 داhvgn -v/q 8vm4s 7v9/pاره ذو airliftاlوw9mdq اf[>g ،-.m41 [hو?< ا7zn -l ib7d1]vh wvn i@ع ib7vd1و?< اhv] f[>g وز?7دة -/m1ا d/0.17ز اr1داد اq? f9yا>z17ز اr1ا . hv?q] -v:1ا fv9i951ا fk7vd.17دة اv?ز ev1دي اuv] fv9yا>z17ز اvr1ا f[>vg 7دةv?ان ز hvt7 وvw?ا -/m1ا -.m41ا w9mdqوl7ل اg:hا in70n . اظvj<ت ا7vh7951ت اwvn f/v~4:d.1 ھv|ه ا7vey01ت 7h79s f/n70n 8] . {vn fv917[ fvehs 7vjgs7a]ت دراfg اh9j1رودا?7ey017s z.iت اf9x7?>1 اl@v:.1<ة l7sد7v9sت f9./017ت اh7951ا. hl -vx7?>1ا iv?ا1.@د -vl -v/.01ا �vh7m17ت اvh79sو f9vx7?>17ت اvey01ا wn f/~4:d.17ت اh7951ا z/] [8 ا]:.7د iv?ا1.@د fveى دhvn fvl>0.1 w9mvdqوl7ل اvg: wvn اiv[7z.1 وn@د?iv ا�v/o1 اdowncomer -17v�.1و riserان �b7v:h ا7vq74.1ة 7v.:[l7sد ]/n ev@د?iv اqvm/1 ^:v�:1ء . اvl -x7?>1و��v ا7v�i1م اv:g.1<ح ،ib7d1ا w[ 7زr1ا i~zs 7صo1ا i[7z.1ء اqm1 fgروh.1ا f9/9r�:17ت ا�1<وف ا?hn w.x f9./01ا �b7:i1ا {n >95q im�s 7jgs7a] . خالد وعلاء الدين al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 2132 (2013) study on the effect of the curvature of solar collector on wind loading coefficients and dynamic response of solar collector aladine abdulkader kazem khalid hameed hussein department of engineering affair / university of baghdad (received 4 february 2013; accepted 30 april 2013) abstract in the current research, the work concentrated on studying the effect of curvature of solar parabolic trough solar collector on wind loading coefficients and dynamic response of solar collector. the response of collector to the aerodynamic loading was estimated numerically and experimentally. the curvature of most public parabolic trough solar collectors was investigated and compared. the dynamic response of solar collector due to wind loading was investigated by using numerical solution of fluid-structure interaction concept. the experimental work was done to verify the numerical results and shows good agreement with numerical results. the numerical results were obtained by using finite element software package (ansys 14). it was found that the change in collector curvature (focal length) lead to remarkable changes in wind loading coefficients (drag, lift, and moment), dynamic response (displacement) and natural frequencies but does not affect the first mode shape. keywords: solar collector, curvature, fluid-structure interaction and finite element. 1. introduction the solar thermal power (stp) plants are used to concentrate the heat on the working substance used in steam production process for electrical generation. solar thermal power plants are primarily installed in flat terrain of high solar irradiation for achieving a high power density [1]. the parabolic trough collector is considered to be the most suitable for concentration task [2]. at flat terrain, the components of plants are subjected to severe aerodynamic problems. the parabolic trough is the main component exposed to such aerodynamic effects. the main environmental problems which affect the parabolic trough performance are the wind-induced vibration and trough instability to truck the sun accurately [3]. the study of dynamic response of solar collector due to environmental conditions is very useful to built suitable control system to adjust collector tracking system. the dynamic response of solar collector can be affected by many factors such as collector geometry, material, fixing, environmental conditions and the accuracy of control system. this research aims to study the effect of the geometry of the collector on the dynamic response of the collector due to wind loading. m.t. lates presents the finite elements analysis of the mechanical behavior for three main solar collector tracking systems: for plate, for dish and for trough solar collectors. the study concentrated on prediction of stresses in solar collectors due to extreme meteorological situations (3cm thick snow layer and 16m/s wind speed acting on the structure oriented at horizontal position [4]. a. miliozzi et.al evaluated wind loads on a parabolic-trough concentrator numerically using the cfd flotran module of ansys finite element code. the study concentrated on evaluating the aerodynamics coefficient for the parabolic trough at three wind speed and different angular position [5]. l. m. murphy carried out a study to discuss the most practical designs for the collector and the test procedures to evaluate the wind loading on the collector. the test results corresponding to numerous wind tests on heliostats, parabolic troughs, parabolic dishes, and field mounted photovoltaic arrays are discussed and the applicability of the findings across the aladine abdulkader kazem al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 2132 (2013) 22 various technologies is assessed [6]. j. a. peterka et. al. carried out a study to define mean and peak wind loads on parabolic dish solar collectors. loads on isolated collectors and on collectors within a fie1d of collectors were obtained. a major intent of the study was to define wind load reduction factors for collectors within a field resulting from protection offered by upwind co1lectors, wind protective fences, or other blockage elements [7]. n. u. gunasena performed a study to determine the feasibility of a novel solar collector design for large scale solar power generation. the design concept involved a large, fixed mirror dish in the shape of a spherical segment, with a tracking collector as opposed to a more traditional tracking concentrator with a fixed or tracking collector [8]. n. hosoya and j.a. peterka carried out comprehensive experimental study to determine the mean and maximum wind load coefficients on the parabolic trough in boundary layer wind tunnel. the wind loading on parabolic trough are determined for different angles of attack, for different wind speeds and for different turbulent intensity. this study showed that the wind loads coefficients are independent of the reynolds number and turbulent intensity [9]. in this paper, the effect of geometry (curvature) of the parabolic trough solar collector on wind loading coefficients and wind-induced dynamic response of the collector was investigated. the wind loading coefficients included drag coefficient, lift coefficient, and moment coefficient. the dynamic response of collector which is studied in current study is the vibrational characteristics (natural frequency, mode shape and damping ratio) of the parabolic trough solar collector and the response (deformation) of the trough surface under the action of wind loading. five scenarios of curvature of most public parabolic trough were considered and the dynamic response of all these scenarios under the action of one wind speed (10m/s) and one angle of attack (θ=90˚) was investigated and compared. 2. solar collector geometry this paper specifically refers to parabolic trough collectors for concentrating sunlight. this type of concentrator has a cylindrical shape, with its parabolic curvature described by the formula (y=x2/4f). the distance (f) represents the position of the focal point of the parabola (the distance of the focal line of the parabola from its vertex). the difference in curvature leads to difference in length of aperture (d) and height (h). fig. 1. profile of the present parabolic concentrator [10]. 3. scenarios of curvature five of the most public parabolic trough curvatures were chosen for current study. the curvatures of these five types of collector are listed in table (1) [11, 12 , 13]: table 1, curvatures of collectors. scenario collector focal length(m) parabola s1 ls-1[11,12] 0.94 y=x2/3.7 6 s2 ls-2, duke solar[11,12] 1.49 y=x2/5.9 6 s3 ls-3, euro trough[11,12] 1.71 y=x2/6.8 4 s4 new ist[11,12] 0.76 y=x2/3.0 4 s5 mittrough[13] 0.1 y=x2/0.4 the investigation of the difference of dynamic response of different collectors due to wind loading requires the same aperture area for all collectors under the study. so, the aperture length (d) and the length of the parabolic trough must be the same for all prototypes. therefore, the aladine abdulkader kazem al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 2132 (2013) 23 difference between the collectors belongs to the difference in height (h). this difference in geometry will affect the flow characteristic distribution around the trough and subsequently will affect the dynamic response of the trough. 4. numerical simulation ansys is a finite element analysis software package. in the current study, ansys workbench is used for fluid-structure interaction (fsi) analysis. fsi applications involve coupling of fluid dynamics and structure mechanics disciplines as in figure (2) [14]: • fluid flow exerts hydrodynamic forces on a structure and deforms and/or translates the structure. • deformed or translated structure imparts displacement to the fluid domain and changes its shape and thus changes the fluid flow. 5. modes of fsi modeling the main characteristics of modes of fsi modeling are listed in table 2. table 2, comparison between modes of fsi modeling. fsi simulation (1 way) fsi simulation (2 way) very small deformations in the structure large structural deformations calculate and pass flow fields from cfd to the structural analysis fea code iterate between cfd and fea codes no need to update and recalculate flow need to update and recalculate flow fig. 2. coupling procedure of 2-way fluidstructure interaction [14]. in the current paper, in current paper, both 1way and 2-way fluid-structure simulation are done. for 1-way simulation, the (fluent ansys 14) version was used to evaluate the flow characteristics around the parabolic trough and the aerodynamic forces exerted by wind which was mapped to mechanical ansys to evaluate the response due to these aerodynamic forces. for 2way simulation, the ansys 14 version was used with a fem modeling facility for the trough structure and the cfx module for modeling the fluid flow. these two physics could be combined using the mfx multi-field solver. the key of the coupled simulation is that the fluid flow induces forces on the parabolic trough, which deforms accordingly based on the fem calculations. the deformation was feed back to the cfd mesh. 6. modal analysis the modal analysis is used to determine the vibration characteristics (natural frequencies and mode shapes) of the structure. it also can be a starting point for the harmonic response analysis. the basic equation solved in a typical modal analysis is the classical eigenvalue problem. many aladine abdulkader kazem al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 2132 (2013) 24 numerical methods are available to solve that equation. 7. mesh description two domains are used in numerical simulation, fluid domain and structure domain. the element used for structural analysis is (shell 281). the shell281 element is suitable for analyzing thin to moderately-thick shell structures. the element has eight nodes with six degrees of freedom at each node: translations in the x, y, and z axes, and rotations about the x, y, and z-axes. when using the membrane option, the element has translational degrees of freedom only [15]. this element is shown in figure (3). figure (4) shows the mesh density of the structure. fig. 3. element shell 281 geometry. [15]. fig. 4. mesh of structure. for fluid domain, two types of elements were used. for a surface mesh, a higher order triangular element with hanging node was used as shown in figure (5-a) and for three dimensional mesh, higher order tetrahedral element with hanging nodes was used as shown in figure (5-b). figure (6) shows the mesh topology of fluid domain. fig. 5. types of elements of fluid domain [16]. fig. 6. the mesh topology of fluid domain. 8. experimental work to verify the numerical results, an experimental work to measure the dynamic response of collector was done. the verification was done for one type of collector (mit-trough). the vibrational characteristics of the trough (natural frequencies and mode shape) were measured first. then the dynamic response (displacement) under the action of wind loading was measured. one wind velocity (10m/s) and one angle of attack (θ = 90˚) where the aperture is parallel to wind direction are used in current study. aladine abdulkader kazem al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 2132 (2013) 25 9. experimental apparatus and setup the experimental work setups consist of dynamic response measurements (vibration behavior) and wind loading setup. the dynamic response measuring system consists of accelerometer, charge amplifier, oscilloscope and parabolic trough prototype. the schematic diagram of dynamic response measuring system is shown in figure (7). fig. 7. schematic diagram of response measuring system. the wind loading (pressure) measuring devices consist of several pressure tabs located on the surface of the trough. the system recieve simultaneous signal samples from (8) individual pressure transducers at maximum design rate of (12500) samples per second per channel. the signals are transmitted from pressure transducers to (8) channels to analog to digital convertor serial communications usb (daqmx 100 ksa/sec) connected to controller software (labview signal express 2010) on personal computer. this system allows digitizing, showing and saving the variations in pressure with time on excel data sheet. the wind tunnel discharge is used as free jet to supply wind at different velocity. this free jet satisfies maximum wind velocity up to (24.6 m/s) at a distance 3m abroad from the free jet. the wind velocity was measured at many points at leeward edge of trough and the average value was calculated. the wind tunnel was adjusted to supply average wind velocity 10m/s at the leeward edge of trough. the velocity of wind is measured by using calibrated flow meter. 10. parabolic trough setup one type of parabolic trough was used in experimental work to examine the validity of using the numerical simulation. the prototype used in this study is made from composite material (polyester resin and e-glass fibers). it is fabricated by using special mold installed for this purpose. the surfaces of trough are polished. the surfaces are smoothed using different wet silicon carbide starting with (260) to (1200) for finishing and then polished using polishing cloth and alumina. the final step is the washing of product by using distilled water for 10 minutes. the final product with dynamic response measuring system is shown in figure (8). the manufacturing processes and the mixing percentage were chosen according to asm metal handbook standard for composite [17]. fig. 8. the parabolic trough made from composite material. 11. result and discussion the results of the current research are divided into three categories: the verification of numerical result, the effect of the curvature on wind loading coefficients and the effect of the curvature on the dynamic response of the collector. 12. verification of numerical results the verification of the numerical results included the verification of flow characteristic and the verification of dynamic response of the parabolic trough. 1. flow characteristics verification: the experimental data of two parameters were used in aladine abdulkader kazem al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 2132 (2013) 26 this verification. the first was the experimental data of static pressure distribution over the parabolic trough and the second parameter was the wind loads coefficients on the parabolic trough. the values of static pressure at specific points on the trough surface were measured experimentally and the counter of pressure over trough surface was drawn and then compared with contour of static pressure which is obtained from numerical work. figures (9 and 10) show these contours of pressure. in both figures the high values of pressure are appears near the edges of trough. also, both experimental and numerical analysis shows that the values of pressure are approximately symmetrical around the centerline of trough. in experimental work, the minimum value of static pressure was 20pa and the maximum value was 70pa while in numerical analysis the minimum value of static pressure was 14.3pa and the maximum value was 71.5pa. it is clear from these figures that the numerical results show good agreement with experimental results. the wind loading coefficients (drag, lift, and moment) are obtained experimentally by using rigid model. this model designed to measure the distribution of local pressures on the front surface of the rigid collector concentrator module. distribution of point pressures can be integrated over the parabolic concentrator surface to numerically determine the total loads on the parabolic trough solar collector. the formula of calculating these coefficients are shown in appendix (1). also, these loading coefficients are obtained numerically. the values of these coefficients are listed in table (3). it is clear from these results that the numerical simulation of the wind loading gives excellent coincides with experimental results. fig. 9. contours of static pressure over trough surface at wind velocity 10m/s obtained from experimental work. fig. 10. contours of static pressure over trough surface at wind velocity 10m/s obtained from numerical analysis. table 3, wind load coefficients of mit trough at velocity 10m/s drag coefficient lift coefficient moment coefficient experimental 0.395 -0.232 0.637 numerical 0.432 -0.214 0.613 error % 9.367 -7.758 -3.767 2. dynamic response verification: the displacement at specific point on trough surface was measured while the wind is applied on trough surface. also, the displacement of the same was evaluated numerically. figure (11) shows the comparison between these results. the comparison between experimental and numerical results of dynamic response shows that the experimental results always larger than the numerical results but the differences were within acceptable range. this difference appears because the actual structure has flexibility more than the numerical model. the numerical results of wind induced response of parabolic trough show that the results of 2-way fluid-structure simulation are close to 1-way simulation. this can be attributed that the response of trough due to this wind velocity was very small and did not alter the flow around the trough. aladine abdulkader kazem al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 2132 (2013) 27 fig. 11. dynamic response of a point parabolic trough surface. 13. the effect of the curvature on wind loading coefficients the flow characteristics and dynamic response of one type of collector (mit collector) are estimated experimentally and numerically. the results show good agreement between them. so, the numerical simulation then used to estimate the flow characteristic and dynamic response of other types of collector and make a comparison between them to find the effect of the curvature on the results. table (4) lists the wind loading coefficients for all types of collectors at wind velocity 10m/s and angle of attack (θ=90˚). it is shown that the drag coefficient increases with the decreasing of focal length. this can be attributed that the decreasing of focal length leads to increasing of side projected area of the trough. this situation will inverse when lift coefficient is considered where the decreasing of focal length leads to decreasing of lift coefficient because that the top projected area will decreased. the difference in moment coefficient is more complicated than the difference in drag and lifts coefficients where the moment is the result of drag force moment and lift force moment. for parabolic trough, the increasing of focal length leads to decreasing the moment coefficient. this indicates that the changing of the curvature of the parabolic trough has more effect on the drag force than that on lift force. figure (12) shows the comparison between the wind loading coefficients. it is clear that the (mit collector) has the highest value of drag and moment coefficients whereas the (euro trough and ls-3 collectors) has the minimum value of drag and moment coefficients. the minus sign of lift coefficient indicates that the lift force directed into downward because of the concave of the trough at this angle of attack. the highest value of lift coefficient was recorded for (euro trough and ls-3 collectors) and the lowest value was recorded for (mit trough). table 4, wind loading coefficients for all types of collector. scenario drag coefficient lift coefficient moment coefficient s1 0.385 -0.267 0.554 s2 0.321 -0.294 0.531 s3 0.303 -0.312 0.501 s4 0.402 -0.235 0.571 s5 0.432 -0.214 0.613 fig. 12. comparison between the wind loading coefficients. 14. the effect of curvature on dynamic response of collector the dynamic response included the natural frequencies, mode shape and displacement due to wind loading. table (5) lists the values of first three natural frequencies of all types of collector and figure (13) shows the comparison between these values. it is obvious from this figure that the values of natural frequencies increase with the decreasing of focal length. this can be attributed to the effect of rigidity of shell structure. the more curvature leads to more rigidity and this leads to increasing the value of natural frequency. the natural frequencies of (mit) collector were higher than the natural frequencies of other types and the increment from first natural frequency to second and from second to third are very large in aladine abdulkader kazem al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 2132 (2013) 28 comparison with the other types. this increment is very little for scenarios (s1, s2 and s3). the presence of folded edges in (mit) collector leads to increasing the values of natural frequency. the values of natural frequencies of scenarios (s2 and s3) are close because the focal lengths are close. table 5, the first three natural frequencies of all types of solar collector. scenario first natural frequency (hz) second natural frequency (hz) third natural frequency (hz) s1 41.54 48.443 51.84 s2 29.563 32.854 37.54 s3 25.74 26.4 28.548 s4 44.56 56.3 56.768 s5 75.016 83.324 134.74 fig. 13. comparison between the natural frequencies of all types of collectors. the numerical estimation of mode shapes shows that the first mode shape is the same for all types of collector. this similarity is caused because that the mode shape depends in very high proportion on the boundary condition and the type of excitation. the difference in focal length does not lead to high changes in the first mode shape. figure (14) shows the first mode shape of all types the collectors. appendix (2) shows the first, second and third mode shape of (mit) collector. fig. 14. first mode shape of the collectors. the responses (displacement) of solar collectors due to wind loadings are evaluated numerically by using 1-way and 2-way fsi to estimate the effect of the curvature on displacement response of collectors. only the results of 2-way fsi will present because the results of 1-way are close to 2-way results as shown in figure (11). figure (17) show the comparison between the dynamic responses of all types of collectors. it is clear from this figure that the displacement of a point on collector surface due to wind loading increases with the increasing of focal length because that the flexibility of collector surface increase with the increasing of focal length. also, it is clear that the scenario (s5) has the highest rigidity between all scenarios. this can be attributed to the presence of folded edges. the changes of displacement are random with time. this indicate that the wind loading excite the collector to vibrate in compound mode of vibration because the wind loading is also random and consist of a spectrum of frequencies. although, the values of displacement are seems to be very small because the wind loading at this wind velocity (10m/s) is not sufficient to excite the collector with high level of response. fig. 15. displacement of collectors due to wind loading. aladine abdulkader kazem al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 2132 (2013) 29 15. conclusion the most important conclusions drawn from this research are: 1the drag coefficient increases with the decreasing of focal length because the decreasing of focal length leads to increasing vertical projected area and this will increase the friction part of drag. 2decreasing of focal length leads to decreasing of lift coefficient because the decreasing of focal length leads to decreasing the horizontal projected area. 3the increasing of focal length leads to decreasing the moment coefficient. 4changing of the curvature of the parabolic trough has more effect on the drag force than that on lift force because the drag force depend on pressure drag and friction drag and the changing the projected area leads to changing in flow pattern around the collector where the friction drag will increase significantly. 5the values of natural frequencies increase with the decreasing of focal length because the rigidity of the collector will increase. 6the difference in focal length does not lead to high changes in the first mode shape. 7the displacement of a point on collector surface due to wind loading increases with the increasing of focal length because the rigidity of the collector will decrease. 16. appendix 1: load coefficients [9] wind load effects are characterized in terms of non-dimensional coefficients. the definitions of the load coefficients are: drag horizontal force coefficient = lift vertical force coefficient = pitching moment coefficient = where fx, fz, and my are the aerodynamic loads. these aerodynamics loads are calculated by integrating the point pressure values over the trough surface. l is the length of the trough, and d is the aperture width of the collector figure (1). the quantity, q, is the mean reference dynamic pressure measured at the height of the solar collector. = here u is the mean wind speed at the height, and ρ is the density of air. 17. appendix 2: the first, second and third mode shape of mit collector fig. 16. first mode shape. aladine abdulkader kazem al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 2132 (2013) 30 fig. 17. second mode shape. fig. 18. third mode shape 18. references [1] h. h. hamad, "study on wind loads coefficients and flow field characteristics around the parabolic trough with stiffeners" university of technology, baghdad, 2012. [2] soteris a. kalogirou " solar thermal collectors and applications" progress in energy and combustion science, 30 (2004), 231–295. [3] n. naeeni, m. yaghoubi, “analysis of wind flow around a parabolic collector” renewable energy 32 (2007) 1898–1916. [4] m.t. lates, mechanical behavior analysis with the finite element method of solar collectors tracking systems. wseas transaction on applied and theoretical mechanics. issn 1991-8747, issue 7, volume 3, july 2008. [5] a. miliozzi, d. nicolini, g. arsuffi and l. sipione. numerical evaluation of wind action on parabolic trough collectors. 8th. world congress on computational mechanics (wccm8). 2008. [6] l.m. morphy, “wind loading on tracking and field mounted solar collectors”, solar energy research institute, golden, colorado, 80401, 1980. [7] j.a.peterka, z. tan, b. bienkiwicz, j. e. cermak, fort collins, “wind loads on aladine abdulkader kazem al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 2132 (2013) 31 heliostats and parabolic dish collectors”, solar energy research institute, 1988. [8] n. u. gunasena, “an experimental study of mean wind forces on hemispherical solar collectors”, m.sc thesis, texas tech university, 1989. [9] n. hosoya and j.a. peterka,” wind tunnel tests of parabolic trough solar collector”, national renewable energy laboratory, 2008. [10] zeinab s. abdel-rehim, ashraf lasheen," experimental and theoretical study of a solar desalination system located in cairo, egypt", science direct, desalination 217 (2007) 52–64. [11] eckhard lüpfert, michael geyer , wolfgang schiel, antonio esteban, rafael osuna, eduardo zarza, paul nava "eurotrough design issues and prototype testing at psa" , proc. of asme int. solar energy conf.-forum 2001, solar energy: the power to choose, washington, dc, april 21-25, pp. 389–394. [12] hank price, eckhard lüpfert, david kearney, eduardo zarza, gilbert cohen, randy gee, "advances in parabolic trough solar power technology" , journal of solar energy engineering, may 2002, vol. 124 / 109 [13] stacy l. figueredo, parabolic trough solar collectors: design for increasing efficiency, ph.d thesis, mechanical engineering department, mit, 2011. [14] h. h. hamad, "dynamic response of solar concentrating power system for self cleaning", ph.d. thesis, university of technology, mechanical engineering department, 2012. [15] ansys theory reference. twelve edition, 2009, ansys inc., south point, canonsburg, 2004. [16] sinan. a. ali “ study effect of riblet upstream wing-wall junction numerically and experimentally” ,m.sc. thesis, mechanical eng. dept. university of technology, 2011. [17] asm handbook, volume 21, composite, 2001. )2013( 21-32 ، صفحة2، العدد9مجلة الخوارزمي الھندسیة المجلد عبد القادر عالء الدین 32 دراسة تأثیر انحناء المجمع الشمسي على االستجابة الدینامیكیة للمجمع الشمسي خالد حمید حسین عالءالدین عبد القادر جامعة بغداد /قسم الشؤؤن الھندسیة الخالصة تركز العمل على دراسة تاثیر انحناء المجمع الشمسي ذو المقطع بشكل قطع مكافئ على معامالت االحمال الھوائیة واالستجابة الدینامیكیة , في ھذا البحث تخداما في العالم وتمت تمت دراسة انحناء اكثر المجمعات الشمسیة اس. تم ایجاد استجابة المجمع لتاثیر االحمال الھوائیة عددیا وعملیا.للمجمع الشمسي تم اجراء الجانب العملي للتحقق من دقة . الھیكل-تمت دراسة االستجابة الدینامیكیة للمجمع الشمسي باستخدام الحل العددي لمفھوم تفاعل المائع. المقارنة بینھا دیة استخرجت باستخدام طریقة العناصر المحددة عن طریق برنامج النتائج العد. النتائج العددیة وقد اظھرت النتائج العملیة تقاربا جیدا مع النتائج العملیة ، الكبح(ادى الى تغیرات واضحة في قیمة االحمال الھوائیة ) البعد البؤري(لقد وجد ان تغییر تقوس المجمع الشمسي . ansys 14المحاكاة الحاسوبي . طبیعیة ولكن نسق االھتزاز االول لم یتأثروكذلك الترددات ال) االزاحة(االستجابة الدینامیكیة ،)الرفع والعزم (microsoft word \345\344\317 \322\345\355\321136-144) al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 14, no. 1, march, (2018) p.p. 136-144 inverse kinematics solution for redundant robot manipulator using combination of ga and nn hind z. khaleel department of control and systems engineering/ university of technology/ baghdad/ iraq email: hhindzuhair@yahoo.com (received 8 august 2016; accepted 15 october 2017) https://doi.org/10.22153/kej.2018.10.008 abstract a demonstration of the inverse kinematics is a very complex problem for redundant robot manipulator. this paper presents the solution of inverse kinematics for one of redundant robots manipulator (three link robot) by combing of two intelligent algorithms ga (genetic algorithm) and nn (neural network). the inputs are position and orientation of three link robot. these inputs are entering to back propagation neural network (bpnn). the weights of bpnn are optimized using continuous ga. the (mean square error) mse is also computed between the estimated and desired outputs of joint angles. in this paper, the fitness function in ga is proposed. the sinwave and circular for three link robot end effecter and desired trajectories are simulated by matlab program. joint angles and end effecter positions of robot results values of circular trajectory are better than joint angles end effecter positions of robot results values of nn work in another paper. three link redundant robot workspace is also simulated. the outputs results of best three joint angles are evaluated for two trajectories sinwave and circular, with 50 generations the algorithm is fast. this paper presents the simulations results that are obtained based on matlab r2010b program. keywords: redundant robot, genetic algorithm, neural network, inverse kinematics. 1. introduction one of the main problems for serial-chain manipulators robots is the inverse kinematics problem, where, it needs to find the values of the joint positions given the position and orientation of the end-effector relative to the base. for solving the inverse kinematics problem, there are many solutions [1]. neural networks have been widely applied to solve the robot manipulator inverse kinematics problems. the proposed hybrid approach combined the electromagnetismlike method and the neural network to solve the inverse kinematics problem. extreme learning machine (elm) is used to train the neural network [2]. another neural network solution of the inverse kinematics problem is used for a threejoint robotic manipulator where, the neural network is trained until the error is acceptable [3]. in addition, an artificial neural network (ann) model is presented to find the inverse kinematics solution of a scara manipulator [4]. the genetic algorithm is determined the optimal joint angles in a given search space for three planar manipulator robot that would contribute to a productive and a quality way of material handling and processing [5]. the only genetic algorithm is used to optimization the inverse kinematics of three degrees of freedom model industrial robot manipulator and improving the efficiency of the model [6]. 2. related work 1. the combing of ga and bpnn algorithm of the end effecter positions (x, y) and joint angles of circular trajectory are evaluated as shown in figure 7. these positions and joint angles of circular trajectory are better than the positions and joint angles of circular trajectory of the adrian's work [7]. adrian's work [7] is just used nn hind z. khaleel al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 136144 (2018) 137 algorithm without ga. in addition, in this paper, the end effecter positions (x, y) and joint angles of the sinwave trajectory are demonstrated and simulated as shown in figure 8, while in adrian's work, the only circular trajectory is presented. 2. the proposed flowchart of ga and bpnn algorithm is illustrated as shown in figure 6 and the two difficult trajectories results are simulated, one for the sinwave trajectory and the second for the circular trajectory, but the researchers md and tania [10] are just presented ga and nn algorithm but they did not evaluated any results of any trajectory. 3. modeling of redundant robot manipulator the modeling of three link redundant robot is presented as the following: 3.1. forward kinematics for three link manipulator the forward kinematics means that using the kinematic equations of the three link robot manipulator in order to evaluate the position of the end-effecter from the joint values [7][8]. the three link manipulator robot configuration with all parameters is as shown in figure 1. fig. 1. three link planner manipulator robot configuration [7]. where a�, a�, a� are the three link of robot respectively and th1, th2, th3 are the joint angles. three links are connected by joints whose all axes are perpendicular to the plane of the links. the forward kinematics of the robot equations are illustrated below [7][8]. x� � a� cos�th�� � a� cos�th� � th�� � a� cos�th� � th� � th�� y� � a� sin�th�� � a� sin�th� � th�� � a�sin �th� � th� � th�� …(1) where, (x� , y�) are the coordinates (position) of end effecter for the three link robot and the orientation is �th�) as in eq. 2 th� � th� � th� � th� …(2) the link parameter table of forward kinematics for three link robot is presented in the table 1. table 1. link parameter table of forward kinematics for three link robot link �� (m) �� (deg.) �� (m) �� (deg.) 1 2 0 0 θ� ∗ 2 2 0 0 θ� ∗ 3 2 0 0 θ� ∗ where, di is distance, θi is angle, ai is length and αi is twist angle, θ� ∗= th�, θ� ∗= th� and θ� ∗= th� the ranges of three joint movements are: 0 < th�< π, π < th�< 0, -π/2 < th�< π/2 the three link robot is required to move along the circular trajectory in its workspace. the coordinates of the circle equation are demonstrated as below: x� � x� � r cosφ y� � y� � r sinφ ...(3) where, (x�, y�) are the desired position of the end-effecter, (x�, y�) are the coordinates of the circle's center, r is the circle's radius. the angle (φ) ranges between 0 and 2π. the desired orientation of the end-effecter is expressed by: th! � tan #� �y� /x�� ...(4) the three link robot is also move along the sinwave trajectory in its workspace. the coordinates and the desired orientation of the endeffecter are expressed as: x� � 0: 2π , y� � sinx� …(5) ph* � tan #�� y� /x�� …(6) by using the forward kinematics eq. 1 and eq. 2 the workspace of redundant three link robot are simulated for 1000 random points as shown in figure 2: hind z. khaleel al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 136144 (2018) 138 fig. 2. simulation results of three joints for threelink robot workspace. where the black line is the first link, the red line is the second link and the blue line is the third link of redundant robot. 4. combination of ga and nn algorithm in this paper, the ga is used in order to optimize the weights of nn as explained in below: 1the initialize inputs are end effecter position and orientation�x�, y�, th�) from eq. 1 and eq. 2 and initialization the weights and biases values randomly. 2 bpnn algorithm is divided into three programs in order to evaluate each target output so that we have three programs one for th�, second for th� and third for th�. 3the multilayer feed forward neural networks consist of three layers. there are three programs, in each program the number of these layers is: input layer= 3, hidden=3 and output=1 for neuron=30 so that finally there are three outputs of joint angles. 4 the back propagation neural network (bpnn) is used and the epoch=1000 as shown in figures (3, 4, 5). fig. 3. bpnn structure for three-link robot of th1 output. fig. 4. bpnn structure for three-link robot of th2 output. fig. 5. bpnn structure for three-link robot of th3 output. 5the performance of the neural network is evaluated by the general form of mean square error (mse) for output is: mse � � . / �desired2 3 estimated2� �. 25� …(7) hind z. khaleel al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 136144 (2018) 139 where, n: total number of samples. 6if the mse < minimum error then go to optimise the weights and biases values by using continuous ga. 7the continuous ga is programmed using toolbox [9] and the parameters are shown in table 2: table 2. the specifications of ga simulation parameter value population 30 number of generations 50 crossover rate 80% mutation rate 5% 8the fitness function is proposed as minimization the following form: fitness � � �789� …(8) according to the step 2 there are three programs so that the eq. 8 is applied once time in each program in order to get the optimal angles outputs (th1, th2, th3) by optimization the nn weight values. figure 6 shows that the proposed flowchart of the combination ga and bpnn algorithm as compared with [10]. in this paper, the proposed equation is used as a fitness function as in eq. 8 and also, the continues ga is used in order to optimize the weights values. the continues ga is used because is faster than the binary ga. the two difficult trajectories are presented, one for sinwave trajectory and second for circular trajectory. the results of this paper are demonstrated the best results of joint angles for three link redundant robot. as compared with another work of the researchers md and tania [10] where, they did not have any results of any trajectory. fig. 6. flowchart of bpnn optimization by ga. 5. simulation and discussion results matlab program version r2010b is used in this work in order to simulate the results of three link redundant robot by using combination of ga and nn algorithm. in this paper the outputs results is evaluated of best three joints angles �th�, th�, th�� in radians of the sinwave and the circular trajectory for the redundant three link robot as shown in the following table 3 and table 4: hind z. khaleel al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 136144 (2018) 140 table 3. best three joints angles results of the sinwave trajectory for three link redundant robot. table 4, best three joints angles results of the circular trajectory for three link redundant robot. th1(rad.) th2(rad.) th3(rad.) 1 2.09439510239320 2.09439510239320 -4.18879020478639 2 2.79682251513915 2.25366107507819 -4.26842319112889 3 2.71152693748771 2.40412061902860 -4.34365296310410 4 2.62427838158158 2.54472526439636 -4.41395528578797 5 2.53526739838127 2.67462289897448 -4.47890410307703 6 2.44446364128157 2.79330131331349 -4.53824331024654 7 2.35159812137175 2.90073067337049 -4.59195799027504 8 2.25618015885843 2.99749242117126 -4.64033886417542 9 2.15756521427283 3.08487018524838 -4.68402774621398 10 -1.06323016907846 3.11831562487515 -1.55915781243758 11 -1.09481259810948 3.04305133092376 -1.52152566546188 12 -1.13254807333171 2.96945160644182 -1.48472580322091 13 -1.17282514346554 2.89434286113368 -1.44717143056684 14 -1.21168625695458 2.81483514145648 -1.40741757072824 15 -1.24526823875282 2.72868180908046 -1.36434090454023 16 -1.27025409882385 2.63451890278899 -1.31725945139450 17 -1.28420404400100 2.53192829443235 -1.26596414721617 18 -1.28568282337062 2.42132944016560 -1.21066472008280 19 -1.27418523676859 2.30375290665779 -1.15187645332890 20 -1.24992622513004 2.18056245366256 -1.09028122683128 21 -1.21357817080457 2.05317572280596 -1.02658786140298 22 -1.16601680014912 1.92280583262665 -0.961402916313326 23 -1.10810435642057 1.79022314001794 -0.895111570008968 24 -1.04051183255196 1.65552230081735 -0.827761150408674 25 -0.963563644590466 1.51786835868874 -0.758934179344371 26 -0.877069353067111 1.37517061049141 -0.687585305245703 27 -0.780065882625219 1.22355531083850 -0.611777655419249 28 -0.670264929463752 1.05625087844625 -0.528125439223125 29 -0.542489244228584 0.860473857929541 -0.430236928964771 30 -0.382265572924653 0.604664848551176 -0.302332424275588 th1(rad.) th2(rad.) th3(rad.) 1 -0.359000500128900 1.74470794844022 -0.891416538376323 2 -0.349000367928000 1.74470829362557 -0.880525068783556 3 -0.319568694854553 1.73157976642175 -0.863870052585719 4 -0.259220256446807 1.72581950794822 -0.861147611399690 5 -0.225801224656687 1.73670909020314 -0.868219308432655 6 -0.202804732134982 1.76905729194382 -0.891939490523948 7 -0.190725784329956 1.83226560408357 -0.918965817896581 8 -0.186648895748110 1.90991302234134 -0.965276548758722 9 -0.207409242369409 1.99777818433564 -0.993677994456423 10 -0.211033839456256 2.06970777585943 -1.05095161771735 11 -0.222800551424235 2.16448724068362 -1.11296511384970 12 -0.298593737649912 2.31664157226902 -1.14749549766792 13 -0.323658967067925 2.40977504100077 -1.21451016137534 14 -0.386628436397731 2.50458713022614 -1.24553517872607 15 -0.469689148396207 2.61568585061130 -1.31873208478356 16 -0.553184555200184 2.68625454397890 -1.34068568646420 17 -0.637319007507458 2.77123450838716 -1.37817289235731 18 -0.696122532778854 2.80714614211468 -1.40876908296648 19 -0.809744922978563 2.83702052480132 -1.41827793872577 20 -0.891817858560614 2.82927432255935 -1.41558668669993 21 -0.918072453635902 2.75427010517449 -1.40346938555446 22 -0.990258741674132 2.74176278949666 -1.38096679821293 23 -0.995110369446019 2.65892617286818 -1.33715324615576 24 -0.999999999999810 2.61648188831068 -1.28374208696240 25 -0.958696617519971 2.51550410086786 -1.24420863108735 26 -0.849059015280863 2.31437465818569 -1.18259768460465 27 -0.819666197772313 2.24490448157502 -1.12570211327658 28 -0.757983669931919 2.14688005730974 -1.08253153714546 29 -0.694423514277570 2.07019207007971 -1.03606206660692 30 -0.628635577131678 2.00167217994412 -0.995038006886263 hind z. khaleel al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 136144 (2018) 141 figure 7 below shows that the desired circular trajectory is simulated depending on eq. 3 and eq. 4. where, the combing of ga and bpnn algorithm of the end effecter circular trajectory is evaluated and it is better than the circular trajectory of the adrian's work [7] where, the adrian's work is just used nn algorithm. fig. 7. the three link robot end effecter and the desired circular trajectories. in figure 8 the three link robot sinwave end effecter trajectory is simulated according to combine of ga and bpnn algorithm, while, the desired sinwave trajectory is simulated according to the eq. 5 and eq. 6. fig. 8. the three link robot end effecter and the desired sinwave trajectories. in each trajectory there are three fitness functions are evaluated according to the eq. 8 as shown in figures (9, 10, 11, 12, 13, 14), where the black color is the best fitness values and the blue color is mean fitness: fig. 9. best fitness value for :;< output of sinwave trajectory and average distance between individuals. fig. 10. best fitness value for :;= output of sinwave trajectory and average distance between individuals. hind z. khaleel al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 136144 (2018) 142 fig. 11. best fitness value for :;> output of sinwave trajectory and average distance between individuals. fig. 12. best fitness value for :;< output of circular trajectory and average distance between individuals. fig. 13. best fitness value for :;= output of circular trajectory and average distance between individuals. fig. 14. best fitness value for :;> output of circular trajectory and average distance between individuals. 6. conclusions in this paper the combing of ga and nn algorithm is presented in order to solve the problem of inverse kinematics for three link redundant robot. the inputs ( x�, y� , th�) are end effecter position and orientation of the three link robot. the back propagation neural network (bpnn) is used for training the data. the outputs of bpnn are computed then the mse is evaluated between the estimated and desired outputs. the proposed fitness function is computed with ga. the continues ga is used in order to optimize the weights values with training the data in bpnn by combing ga and nn algorithm. this algorithm is presented in order to solve the inverse kinematics problem and to compute the best values of three joint angles. the continues ga is so fast with 50 generations. the best joint angles outputs results (th1, th2, th3) of sinwave and circular trajectories are evaluated from the combing ga and nn algorithm. in addition, the simulation of three link redundant robot workspace is presented. notation x�,y� position of end effector three link robot th�, th� , th� three joint angles of three link robot th� orientation of three link robot x�, y� desired position of the end-effecter of the and sinwave circle trajectories hind z. khaleel al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 136144 (2018) 143 x�, y� coordinates circle's center r circle's radius th! desired orientation of the end-effecter of the circle trajectory ph* desired orientation of the end-effecter of the sinwave trajectory ga genetic algorithm nn neural network bpnn back propagation neural network mse mean square error m meter di distance θi angle ai length αi twist angle deg. degree rad. radian greek letters φ circle's angle θ* joint angle 7. references [1] bruno siciliano, oussama khatib, springer handbook of robotic, springer-verlag berlin heidelberg, 2008. [2] y. feng, w. yao-nan and y. yi-min, inverse kinematics solution for robot manipulator based on neural network under joint subspace, int j comput commun, issn 1841-9836, vol.7, no. 3 september, pp. 459-472, 2012. [3] raşit köker, cemil oz, tarık c¸ akarb and hüseyin ekiz, a study of neural network based inverse kinematics solution for a threejoint robot, elsevier, robotics and autonomous systems 49 -227–234, 2004. [4] panchanand jha, bb biswal, a neural network approach for inverse kinematic of a scara manipulator, international journal of robotics and automation (ijra), vol. 3, no. 1, issn: 2089-4856, march, 2014. [5] f.y.c. albert, s.p. koh, c.p. chen, s.k.tiong and s.y.s. edwin, optimizing joint angles of robotic manipulator using genetic algorithm, iacsit press, singapore, 8ipcsit vol.2, 2011. [6] j. ramirez a., and a. rubiano f., optimization of inverse kinematics of a 3r robotic manipulator using genetic algorithms, international journal of mechanical, aerospace, industrial, mechatronic and manufacturing engineering vol:5, no:11, 2011. [7] adrian-vasile duka, neural network based inverse kinematics solution for trajectory tracking of a robotic arm, elsevier, the 7th international conference interdisciplinarity in engineering, 2014. [8] adri`a colom´, smooth inverse kinematics algorithms for serial redundant robots, master thesis, institut de rob`otica i inform`atica industrial, 2011. [9] http://www.mathworks.com/help/pdf_doc/ga ds/gads_tb.pdf. accessed on 1/08/2016. [10] md. mijanur rahman, tania akter setu, an implementation for combining neural networks and genetic algorithms, ijcst vol. 6, iss ue 3, july – sept., 2015. )2018( 136-144، صفحة1د، العد14دجلة الخوارزمي الهندسية المجلمهند زهير خليل 144 nnو ga لـ دمجمناور باستخدام المتعدد الروبوت لل العكسيةالكينماتيكا حل هند زهير خليل قسم هندسة السيطرة والنظم / الجامعة التكنولوجية / العراق/ بغداد hhindzuhair@yahoo.com :البريد االلكتروني ________________________________________________________ الخالصة ةالمتعدد ةالمناور اتروبوتالكينماتيكا العكسية ألحد لل تقدم حال. هذه المقالة المتعدد المناورللروبوت جداً ة معقدةالعكسية هي مشكل الكينيماتيكاحساب اتجاه الروبوت و عالمدخالت هي موق . nn (الشبكة العصبية)و gaة الجينية ) خوارزمي(ال ذكيةال خوارزمياتالاثنين من دمجطة سابو (الروبوت الثالثي) ة الجينية خوارزميال باستخدام االفضل تعد bpnnوزان اال ).bpnn(المنشورة العكسية . تدخل هذه المدخالت إلى الشبكات العصبيةالروابط الثالثي زوايا المشتركة.للطلوبة مخرجات المقدرة والمالأيضا بين mseيتم احتساب (متوسط مربع الخطأ) .ga ةمستمرال محاكاتها ببرنامج وتمطلوبة الم الروابطروبوت ثالثي ال لنهاية طرف يةو الدائر ةالموج اتتم اقتراحها. مسار gaدالة الفتنس في ،في هذه المقالة matlab . نهاية الطرف للروبوت و مواقع زوايا المشتركةالنتائج للمسار الدائري افضل من نهاية الطرف للروبوتو مواقع زوايا المشتركةالنتائج ان نتائج المخرجات الفضل ان .الروابطمتعدد الروبوت الثالثي مساحة كما تم محاكاة . nnحيث فقط في العمل االخر تم استخدام عمل اخر لللمسار الدائري باالعتماد ة التي يتم الحصول عليها نتائج المحاكا مقالةسريعة. تقدم هذه ال فانها خوارزميةلل جيل ٥٠. ب والدائري يمساريين الموجلتم حسابها لزوايا ثالث .matlab r2010bبرنامج على د عامر al-khwarizmi engineering journal, vol. 10, no. 2, p.p. utilizing a magnetic abrasive finishing technique (m adaptive department of automated manufacturing engineering / alkhwarzmi college of engineering/ university of baghdad e-mail: amermoosa@kecbu.uobaghdad.edu.iq (received 3 october abstract an experimental study was conducted for abrasive finishing technique (maf) on brass process where the cost is high and much more susceptible to surface damage as compared to other materials. four operation parameters were studied, the gap between the work generate the flux, the rotational spindale speed and amount of abrasive powder size considering constant linear feed movement between machine head and workpiece. adaptive for evaluation of a series of experiments an optimized and usefully achieved by obtained results predicted by model simulation and that of direct measure is 2.0222 % keywords:magnetic abrasive finishing (maf), adaptive roughness, (rmse) root mean square error, membership 1. introduction magnetic abrasive finishing (maf) is a super finishing method comparing with the other traditional operation of surface finishing grading, lapping etc., due to the attitude magnetic flux controlling to its cutting force combining with flexibility of magnetic and brush shape which minimize the possibility micro cracks on the surface of the workpiec (maf) the workpiece is held between the machine table that imposed to directional feed rate and the magnetic poles of the head nose (inductor) where the gap between the workpiece nose is filled with abrasive particle powder that shaped by the flux. this configuration act as smooth grinding brush and behaves multipoint cutting tool operation [1][2].wang hu [3] described the principle of the process khwarizmi engineering journal, vol. 10, no. 2, p.p. 4956 (2014) utilizing a magnetic abrasive finishing technique (maf adaptive nero fuzzy(anfis) amer a. moosa department of automated manufacturing engineering / alkhwarzmi college of engineering/ university of baghdad amermoosa@kecbu.uobaghdad.edu.iq 3 october 2013; accepted 15 april 2014) for measuring the quality of surface finishing roughness plate which is very difficult to be polish by a conventional machining is high and much more susceptible to surface damage as compared to other materials. four gap between the work piece and the electromagnetic inductor speed and amount of abrasive powder size considering constant linear feed head and workpiece. adaptive neuro fuzzy inference system (anfis) nd a verification with respect to specimen roughness obtained results were an average of the error between the surface roughne t of direct measure is 2.0222 %. finishing (maf), adaptive neuro fuzzy inference system (anfis), (ar) average membership function (mf). (maf) is a super the other finishing like attitude of the magnetic flux controlling to its cutting force powder e possibility of the surface of the workpiece. at between the t imposed to directional feed rate (inductor) and the powder that this configuration act as smooth grinding brush and behaves like wang and of the process and finishing characteristics of unbounded magnetic abrasive within internal tubing finishing. they also deal with the design and fabrication of maf setup for finishing three kinds of materials tubing, such as (ly12) aluminum alloy, ( steel and (h62) brass. geeng et a described the process principles and its characteristics of unbounded magnetic abrasive within cylindrical magnetic abrasive finishing. they investigated the finishing characteristics on surface roughness and material removal as well as their mechanisms.mori et al. [5] examined the magnetic field, acting forces and provides a fundamental understanding of the process mechanism. a planar type process for a non magnetic material, stainless steel, was introduced.maiboroda and khomenko [6] investigated how the frictional force between magnetic-abrasive powders and(ti al-khwarizmi engineering journal af) via department of automated manufacturing engineering / alkhwarzmi college of engineering/ university of baghdad roughness using magnetic conventional machining is high and much more susceptible to surface damage as compared to other materials. four piece and the electromagnetic inductor, the current that speed and amount of abrasive powder size considering constant linear feed (anfis) was implemented change has been between the surface roughness (anfis), (ar) average finishing characteristics of unbounded magnetic rasive within internal tubing finishing. they also deal with the design and fabrication of maf setup for finishing three kinds of materials tubing, (316l) stainless geeng et al. [4] also and its finishing characteristics of unbounded magnetic abrasive within cylindrical magnetic abrasive finishing. they investigated the finishing characteristics on surface roughness and material removal as well as al. [5] examined the magnetic field, acting forces and provides a fundamental understanding of the process mechanism. a planar type process for a nonmagnetic material, stainless steel, was introduced.maiboroda and khomenko [6] onal force between ti) alloy surface mailto:amermoosa@kecbu.uobaghdad.edu.iq mailto:amermoosa@kecbu.uobaghdad.edu.iq amer a. moosa al-khwarizmi engineeri varies during magnetic-abrasive machining in relation to the technological parameters. they studied experimentally the effects of five types of powders with different grain sizes. dhirendra et al. [7] reported the experimental findings about the forces acting during maf and provides correlation between the surface finish and the forces. nazar [8]reported the experimental findings the forces acting during maf and provides correlation between the surface finish and this force. it is concluded that forces and the change in surface roughness (δra) increase with increasing of the current value impose electromagnet (or magnetic flux density) and decreasing in the working gap. the researchers filled the working gap with a homogeneous mixture of silicon carbide abrasives and ferromagnetic iron particles at a ratio of 25:75 weight, respectively. in this paper a model based on (anfis) for (amf) process was performed using brass metal workpieces to estimate its surface roughness an adoption of objective simulation is carried to optimize the solution obtained by the model. 2. experiments an electromagnetic inductor was designed and manufactured to implement (maf) on workpiece by milling machine as shown in fig. 1. consist of (1) inductor of steel road wrapped with a coil of wire (2) work piece (brass) (3) d.c power supply (4) machine spindle (5) inductor body (6) shank (7) milling table. while fig. 2. shows (1) magnetic powder particle(2) abrasive brush (3) gap between head nose and work piece. the inductor material is low carbon steel (c15) with a cross section of (a) =14cm2 and long of (l)is (75mm) and copper wire diameter of (ø)=1mm and number of turns is (n 2400) while the powder is (40%) iron and (60%) quartz centered in (1200 c°) and then were crushed to (150μm) of approximated diameter shows under sem, jsm-6360 lv scanning microscope in fig. 3. the process parameters has been changed during the operation as follows: the working gap from (10 to 20)mm,current responsible to change the flux from (1.5 to 3.5) amp, volume of the powder from (2 to 4) cm3 and the rotation speed from (175 to 5250) rpm with a feed rate of (30) mm/min. khwarizmi engineering journal, vol. 10, no. 2, p.p. 50 abrasive machining in relation to the technological parameters. they studied experimentally the effects of five types of the experimental findings about the forces acting during maf and provides correlation between the surface finish the experimental findings of the forces acting during maf and provides tween the surface finish and this change in surface roughness (δra) increase with the value impose to the electromagnet (or magnetic flux density) and the the researchers with a homogeneous mixture of silicon carbide abrasives and of 25:75 in in this paper a model based on (anfis) for (amf) process was performed using brass metal ghness and carried out solution obtained by the model. an electromagnetic inductor was designed and manufactured to implement (maf) on workpiece by milling machine as shown in fig. 1. consist of (1) inductor of steel road wrapped with a coil of wire (2) work piece (brass) (3) d.c power supply le (5) inductor body (6) shank (7) milling table. while fig. 2. shows (1) magnetic powder particle(2) abrasive brush (3) the inductor material is low carbon steel (c15) with a cross section of (a) =14cm2 and long of l)is (75mm) and copper wire diameter of 1mm and number of turns is (n 2400) while the powder is (40%) iron and (60%) quartz ) and then were crushed to m) of approximated diameter shows under 6360 lv scanning microscope shown the process parameters has been changed during the operation as follows: the working gap from (10 to 20)mm,current responsible to change the flux from (1.5 to 3.5) amp, volume of the powder from (2 to 4) cm3 and the rotation speed 75 to 5250) rpm with a feed rate of (30) fig. 1. magnetic abrasive devices. fig. 2. magnetic brush of electromagnet poles. fig. 3. sem (x 100) of magnetic abrasive particles. 3 2 ng journal, vol. 10, no. 2, p.p. 4956 (2014) fig. 1. magnetic abrasive devices. fig. 2. magnetic brush of electromagnet poles. fig. 3. sem (x 100) of magnetic abrasive particles. 1 amer a. moosa al-khwarizmi engineering journal, vol. 10, no. 2, p.p. 4956 (2014) 51 the work piece is divided into nine parts represent the three level configuration as shown in tables (1and 2) respectively. some of them were operated traditionally and the other has been simulated as an artificial intelligent base of (anfis) (fig. 4.) each piece is fixed in such a way that the center of the work piece coincides with the center of the head nose. the required gap between them is filled with powder abrasive particles. after each experiment, the change in surface roughness value (δra) is determined by measuring (ra) via tester tr220 (fig. 5). table 1, three level parameters. table 2, parameters configuration. fig. 4. photo of some of the work pieces. fig. 5. surface roughness tester, (tr-220). 3. anfis optimization technique anfis is a hybrid predictive method that combines the neural network tool to the fuzzy approaches to generate mapping scheme between input parameters and output results. the structure of this model consist of five layers, each layer is constructed by several nods. anfis behave just like the neural network where the structure of each layer is obtained by the node of the previous layers as shown in fig. 6.a numbers of initiating data among all data set have been selected as training data, and then the trained network was validated by other data set. the root mean square error (rmse) is applied to this work for inspection purposes of the trained model as follows : rmse = √ [1/tr∑ tri = 1(ti − yi)^2] …(1) where (tr) are the total number of training samples, (ti)is the real output value, and (yi) is the anfis output value in training from matlab parameters units levels rotational speed (p1) rpm 175 350 525 coil current (p2) amp 1.5 2.5 3.5 volume of powder (p3) cm3 2.0 – 3.0 – 4.0 working gap (p4) mm 1.0 1.5 2.0 exp. factors rotational speed (p1) (rpm) coil current (p2) (amp) volume of powder (p3) (cm3) worki ng gap (p4) (mm) 1 175 1.5 2 2 2 350 2.5 3 3 3 525 3.5 4 4 4 350 1.5 4 4 5 525 2.5 2 2 6 175 3.5 3 3 7 525 1.5 3 3 8 175 2.5 4 4 9 350 3.5 2 2 amer a. moosa al-khwarizmi engineeri platform using fuzzy tool representing by anfis guide user interface with the adoption the attitude of e and c. a fuzzy inference system of sugeno model is conducted as follows: a two rule sugeno anfis has rules of the form if x is a1 and y1 is b1 then f = p1 x + q1 y +r1 if x is a2 and y2 is b2 then f = p2 x + q2 y + r2 for the training network fig 3e the rmse was set to (0.02) and the iteration number was (30)epochs where the layers act as follow: layer 1 (fuzzification layer): it transforms the crisp inputs (xi) to linguistic labels ( , like small, medium, large etc.) with a degree of membership. the output of node (oij) or could represent by (ki) is expressed as follows: oij1=ok1= μij(xi) , i= 1...m , j = 1...n where (μij)is the (jth) membership function the input (xi). layer 2 (product layer): for each node (k) in this layer, the the output represents a weighting factor (e) (firing strength) of the rule (k). the output (wk) is the product of all its inputs as follows: fig. 6. 4. results and discussion after using several types of member function, the gaussian function fig. 7. w selected to be more accumulate with modeling behavior as follows: khwarizmi engineering journal, vol. 10, no. 2, p.p. 52 platform using fuzzy tool representing by anfis guide user interface with the adoption the attitude f sugeno a two rule sugeno anfis has rules of the …(2) …(3) for the training network fig 3e the rmse was set to (0.02) and the iteration number was (30)epochs layer 1 (fuzzification layer): it transforms the , like small, medium, large etc.) with a degree of membership. the output of node (oij) or could represent by (ki) is …(4) th) membership function for layer 2 (product layer): for each node (k) in this the output represents a weighting factor (e) (k). the output (wk) is the product of all its ok2 = wk = u1e1(x1)u2e2(x2)…um em k=1…n ,e1,e2…em , =1…n layer 3 (normalized layer): the output of each node (k) in this layer represents the normalized weighting factor (wk|) of the (kth) rule as follows: ok3 = wk| = (wk) / (w1+w2+…wn) layer 4 (de-fuzzification layer): each node of this layer gives a weighted output of the first order tsk-type fuzzy if then rule as follows: ok4 = wk| fk where fk represents the output of (kth) tsk (takagi-sugeno-kang)-type fuzzy rules. layer 5 (output layer): this single represents the overall output (y) of the network as the sum of all weighted outputs of the rules: o5 = y = ∑ nk = 1 (wk| fk) it is inevitable to consider that the fuzzy set is a decision-making process comparison with anfis, which raise the ability of the knowledge base decision-making system with its capability to produce the rules for simulation process. fig. 6. anfis network structure. embership fig. 7. was selected to be more accumulate with modeling u(x)=exp[-(x-c)^2/2σ^2] where: u(x) represents the mf input and x, parameters for gaussian function shape selected from the platform. ng journal, vol. 10, no. 2, p.p. 4956 (2014) ok2 = wk = u1e1(x1)u2e2(x2)…um em(xm) …(5) layer 3 (normalized layer): the output of each this layer represents the normalized weighting ok3 = wk| = (wk) / (w1+w2+…wn) …(6) fuzzification layer): each node of this layer gives a weighted output of the first order type fuzzy if then rule as follows: …(7) where fk represents the output of (kth) tsk type fuzzy rules. layer 5 (output layer): this single-node layer represents the overall output (y) of the network as the sum of all weighted outputs of the rules: …(8) it is inevitable to consider that the fuzzy set is a making process comparison with anfis, which raise the ability of the knowledge base making system with its capability to simulation process. …(9) the mf input and x,σ,c are function shape that amer a. moosa al-khwarizmi engineeri fig. 7. the experimental data are mapped to anfis and evaluates as patterns tanning/testing vectors where the training and testi performance for anfis was checked by equation number (1). the topology of the number of sets and epoch dedicates the number of rules used by anfis that reach 81 rules and its relate to the number of data and a comparison of experimental training /testing measured with those estimated by khwarizmi engineering journal, vol. 10, no. 2, p.p. 53 gaussian function selection box. to anfis /testing formed and testing ked by the the topology of the number of sets and epochs used by sugeno and its relate to the experimental training /testing measured with those estimated by anfis network as shown in f respectively. it is obvious to recognize the simulation fitting that shows good agreement for a wide range of acceptability and reliability. table 3. show the rmse process result of anfis model for a different type fig. 10. show the training error curve. after carrying out the process some of work pieces are shown in fig. 11. fig. 8. training session. ng journal, vol. 10, no. 2, p.p. 4956 (2014) fig. (8 and 9) simulation fitting a wide range of the rmse process result of a different type of mf. where the training error curve. carrying out the process some of work amer a. moosa al-khwarizmi engineeri fig. fig. 10. the error curve during the anfis process table 3, parameters results of anfis model . current mamp gap mmm powder cc 1.5 1 2 1.75 1.12 2.25 2 1.24 2.5 2.25 1.36 2.75 2.5 1.48 3 2.75 1.6 3.25 3 1.72 3.5 3.25 1.84 3.75 3.5 2 4 khwarizmi engineering journal, vol. 10, no. 2, p.p. 54 fig. 9. verification session. fig. 10. the error curve during the anfis process. powder cc speed r/rev rf u error 175 0.13 2.1 218.75 0.21 2.4 262.5 0.16 2.2 306.25 0.111 1.7 350 0.136 1.2 393.75 0.123 2.6 437.4 0.113 2.1 481.25 0.209 1.4 525 0.117 2.5 sum.18.2 18.2/9=2.02 ng journal, vol. 10, no. 2, p.p. 4956 (2014) sum.18.2 18.2/9=2.02 amer a. moosa al-khwarizmi engineeri fig. 11. pieces show the location of smooth mirror 5. conclusion and future work the most effective factor acting on anfis the accuracy of the simulation model which is depend on the type of mf of gaussian shape and the value of rmse which is presume to be low on this operation which is mean more reliability acceptability.the value number of gaussian mf is twice the number of inputs, which are current research and need to be examining to find if this happened by chance or there is a case of correlation. to explain this phenomenon, the researcher intends to approve in future work.the number of rmse is dedicated to make the training epochs continue until it become the target and that corresponding to the amount of epochs been settled and this arise the question the epochs cycle change with the respect to time series how could this situation effect the prediction confidence.this neuro fuzzy model enhance the result with respect to other model such as the traditional neural network because its rabidadaptation too bserve the structure process, also it is adapted to the increasing or adding of new inputs parameters regards to the expansion ability of fuzzy sets numbers and learning rules.more expected future result evaluating a good (quality and quantity) data sampling to obtain smaller results error (less than the acquired value of 0.022) in addition to how the flux shape could effect the powder figuration. khwarizmi engineering journal, vol. 10, no. 2, p.p. 55 show the location of smooth mirror. on anfis is the accuracy of the simulation model which is gaussian shape and to be low on reliability and gaussian mf is inputs, which are four for examining more by chance or there is a ain this phenomenon, in future s dedicated to make continue until it become below amount of arise the question if the respect to time fect the euro fuzzy model enhance the result with respect to other model because of structure of the also it is adapted to the increasing or regards to the s numbers and expected future result is to a good (quality and quantity) data results error (less than in addition to how ld effect the powder figuration. 6. reference [1] s.c. jayswal, v.k. jain, and p.m. dixit, “modeling and simulation of magnetic abrasive finishing process”, international journal of advanced manufacturing technology, vol.26 (2005), pp. 477 [2] ching-tien lin, lieh-dai yang, and han ming chow, “study of magnetic abrasive finishing in free-form surface operations using the taguchi method”, international journal of advanced manufacturing technology, (2006). [3] yan wang, and dejin hu, ”study on the inner surface finishing of tubing by magnetic abrasive finishing”, international journal of machine tools & manufacture, vol.45 (2005), pp. 43–49. [4] geeng-wei chang, biing-hwa, and yan, rong-tzong hsu, “study on cylindric magnetic abrasive finishing using unbounded magnetic abrasives”, international journal of machine tools & manufacture, vol.42 (2002), pp. 575–583. [5] t. mori, k. hirota, and y. kawashima, “clarification of magnetic abrasive finishing mechanism”, journal of materials processing technology, vols.143-144 (2003), pp. 682 686. [6] v. s. maiboroda and e. a. khomenko, “tribotechnical characteristics of ferroabrasive powders in magnetic machining”, journal of powder metallurgy and metal ceramics, vol.42 (200 [7] dhirendra k. singh, v.k. jain, and v. raghuram., “parametric study of magnetic abrasive finishing process”, journal of materials processing technology, vol.149 (2004), pp. 22–29. [8] nazar kais m.naif“study on the parameter optimization in magnetic abrasive polishing for brass plate using taguchi method “journal of college of engineering, vol,3(2011). [9] jae-seobkwak and tae-kyung kwak, “parameter optimization in magnetic abrasive polishing for magnesium plate”, ieee, vol.5 (2010), pp.544–547. ng journal, vol. 10, no. 2, p.p. 4956 (2014) s.c. jayswal, v.k. jain, and p.m. dixit, “modeling and simulation of magnetic abrasive finishing process”, international journal of advanced manufacturing technology, vol.26 (2005), pp. 477–490. dai yang, and hanming chow, “study of magnetic abrasive form surface operations using the taguchi method”, international journal of advanced manufacturing an wang, and dejin hu, ”study on the inner surface finishing of tubing by magnetic abrasive finishing”, international journal of machine tools & manufacture, vol.45 hwa, and yan, tzong hsu, “study on cylindrical magnetic abrasive finishing using unbounded magnetic abrasives”, international journal of machine tools & manufacture, vol.42 t. mori, k. hirota, and y. kawashima, “clarification of magnetic abrasive finishing of materials processing 144 (2003), pp. 682– v. s. maiboroda and e. a. khomenko, “tribotechnical characteristics of ferroabrasive powders in magnetic-abrasion machining”, journal of powder metallurgy 2 (2003), pp.9-10. dhirendra k. singh, v.k. jain, and v. raghuram., “parametric study of magnetic abrasive finishing process”, journal of materials processing technology, vol.149 study on the parameter ic abrasive polishing for brass plate using taguchi method llege of engineering, kyung kwak, “parameter optimization in magnetic abrasive polishing for magnesium plate”, 547. )2014( 4956، صفحة 2، العدد10دجلة الخوارزمي الھندسیة المجلمعامر عبد المنعم موسى 56 التنفیع باسلوب العصیبات المضببة لتطویر التشغیل بطریقة التنعیم باالحتكاك المغناطیسي عامر عبد المنعم موسى جامعة بغداد/ كلیة الھندسة الخوارزمي / قسم ھندسة التصنیع المؤتمت amermoosa@kecbu.uobaghdad.edu.iq :البرید االلكتروني الخالصة الى تم اجراء دراسھ تطبیقیھ لقیاس نوعیة السطوح المنعمھ بطریقة االحتكاك المغناطیسي على عینات لوحیھ من البراص المعروفھ بكونھا تحتاج .التنعیم لمثل ھذا النوع من المعادن من كلف تشغلیھ ومھاره عالیھ وضروف تشغیلیھ خاصھمتطلبات خاصھ في عملیات بین القطب تم اختیار مجموعھ من المعایر المؤثره على ضروف التشغیل لمثل ھذا النوع من التنعیم والذي یتم عن طریق وضع مادة ابریھ لتملى الفراغ اذ تعتبر ھذة الفجوة من المعایر الحساسھ في ھذا النوع من التشغیل فضال عن شدة التیار المستخدم ، مراد تشغیلھا المغناطیسي الدوار للماكنھ وبین العینھ ال .لتولید الحث المغناطیسي وكمیة المادة االبریھ المستخدمھ وسرعة دوران القطب المغناطیسي الحامل لمادة التنعیم على تولیفة مثلى من المعایر ضمن تشكیلة المعایر المستخدمھ في الحالھ العملیھ ووصل االنتفاع الى تم االنتفاع من اسلوب العصیبات المضببھ للحصول % .٢.٠٢٢٢تولیفة مقاربھ للتجارب العملیھ بنسبة خطا الكلفھ التي التحتمل اجراء وان التولیفھ قابلة للتغیر بمعایر مختلفة دون الرجوع الى التطبیق العملي مما یوفر الوقت والمجھود خاصھ للمعادن العالیھ .التجارب العملیھ دون التاكد من صحة المعطیات mailto:amermoosa@kecbu.uobaghdad.edu.iq <4d6963726f736f667420576f7264202d20cce4c7e420cfceede120e6d3cdd120e6dac8cf20c7e1e1d8eddd3134312d20313438> al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 14, no. 3, september , (2018) p.p. 141148 performance augmenting of a vertical axis wind turbine using adaptable convergent ducting system abdullateef a. jadallah** sahar r. farag *** jinan d. hamdi*** *,**,***department of electromechanical engineering / university of technology / iraq *email: abdullateef.aljad@gmail.com **email: dr saharalsakini@yahoo.com ***email: jenanjenan780@yahoo.com (received 29 september 2017; accepted 19 march 2018) https://doi.org/10.22153/kej.2018.03.003 abstract developments are carried out to enhance the performance of vertical axis wind turbines (vawt). this paper studies the performance of the ducted wind turbine with convergent duct (dawt). basically, the duct technique is utilized to provide the desired wind velocity facing the turbine. methodology was developed to estimate the decisive performance parameter and to present the effect of the convergent duct with different inlet angles. the ducted wind turbine was analyzed and simulated using matlab software and numerically using ansys-fluent 17.2. result of both approaches were presented and showed good closeness for the two cases of covering angles 12° and 20°, respectively. results also showed that the convergent duct with an inlet angle 12° and 20° improved the coefficient of performance at a specified tip speed ratio by 25.8% and 33.33% respectively in the productivity of wind turbine. keywords: coefficient of performance, dawt, matlab, vawt, wind turbine. 1. introduction the development of renewable energy has become one of the most important goals due to global warming and the high consumption of energy, in addition to the fossil fuel waste and its impact on the environment in order to deal with these problems by resorting to alternative means of obtaining energy. wind energy has become one of the fastest growing sources of energy. in recent years [1]. there have been many attempts to improve the performance of wind turbines and wolves by adding a tunnel to the torpedo called the shroud [2]. grant and kelly [3] developed and tested a mathematical model of a ducted wind turbine and described the integrations of the turbine according to various domain of building simulation. the study was investigated the concept of ducted wind turbine, and the integration of the wind turbine model mounted inside the building using the simulation tools. abdullateef et al. [4] designed and fabricated vertical axis wind turbine (vawt) are revealed in this work. six different geometries of the vawt rotors were designed and manufactured. these geometries are: two straight bladed (2hb) vawt, three straight bladed (3hb) vawt, savonius rotor (si), savonius rotor (sii), savonius rotor (siii) and savonius rotor (siiii). they compared their results with an adopted methodology and attained reasonable agreement. a number of researches have been interested in studying this concept [5-8]. performance of wind turbine can be improved just in case of good alignment between the channel and the wind, and the flow is no so gusty. deterioration and other phenomena related to the wind turbine is demonstrated by s ّ◌rensen [9], where various, models to portend aerodynamic forces, design of rotor-blade airfoils, analysis of wind ranch, and wind turbine wake simulations, are also considered. one of the most important issue with abdullateef a. jadallah al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 141148 (2018) 142 duct wind turbines is the bulk of the wake, which can give rise to wake interference, which can cause fatigue loading of down wind turbines and also reduce the efficiency of wind farms. these are some of the reasons why wind turbine wake structure has been studied extensively [10-11]. turbines built up inside small enshroud entries are also used to transfer power to the sensing system in ducts and pipes as shown in howey et al. [12]. hansen et al. suggested that the augmentation is limited to the relative speed-up under zero thrust. based on inviscid 1d analysis of pressure variation through the duct [13]. the convergent duct system is considered in this paper and a comparative performance has been carried out on the convergent ducted turbine and the traditional turbine. the convergent duct turbine has the ability to accelerate the air flow through a converging intake and increasing the power that can be extracted from the air flow. 2. design of the convergent ducting system wind turbine the flow is assumed to be one dimensional steady and incompressible thus, flow the one dimension of governing equations are: � �� ��� = 0 … �1 v �� �� + � � �� �� = 0… … �2 it will be noted that because the flow variables depend only on x in steady flow, these equations do not involve partial derivatives. analytical solutions to equations 1 and 2 are easily obtained purpose here is not, therefore, to imply that it is necessary to solve this set of equations numerically. it is simply to illustrate some of the consideration that are involved in obtaining numerical solution to the equations governing incompressible fluid flows. the iterative finite– difference procedure used for the designed duct is shown in figure (1) [14]. this domain is divided into series of segment of length each of length ∆� thus: ∆� = � ��� … �3 where n is the number of grid points and l the length of the solution domain fig. 1. convergent duct system. area at each section may be calculated as: a�=��2(�� -��) ��� + (�� − �� �� � … �4 where �� = ���� + ∆�. the density is constant because the flow is incompressible so the velocity at each section may be calculated as: �= �� "�"� … �5 the pressure at point 2,,…n are then found using a first order finite difference approximation to eq.(2).using �� �� = �����$% &� …(6) �� �� = '� �'�$% &� …(7) the pressure is then calculated (� = (��� -�� � � ) − ��� …(8) applying this equation sequentially from points i= 2,…,n allows the values of (� at each of these points . power coefficient can be calculated from [15] *+,= *∗ / … �9 3. numerical analysis of the convergent duct wind turbine the flow inside the duct and over the vawt blade is solved numerically using ansysluent 2017.the following section include. 3.1 governing equations the dynamics of computational fluids include the differential governing equations and the nature of the flow which determines the possibility of the application for governing equations. mathematical representations of these equations can be used in a group or individually depending on the uses of the output desired. equation include the properties for any fluid which represent the conservation for mass and momentum. in such case, we are using abdullateef a. jadallah al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 141148 (2018) 143 with the equation of continuity with the application of the model k-ω .the continuity equation or maintaining the mass provided as follows: ∂ρ ∂t + ∂ρu ∂x + ∂ρu ∂y + ∂ρu ∂z = 0 … �10 momentum equation for incompressible flow is given below: ρ 9∂u:∂t + ∂u;u:∂x; < = − ∂ρ ∂x: + g: + μ ∂?u:∂x;x; = 0 … �11 3.2 geometry a 2d analysis for naca 0012 air foil is treated by ansys design. the convergent duct system for different geometry formed after create the geometry of airfoil. three airfoils are creating for bladed and separated by 120 ° . fig. 2. 2d geometries of convergent duct. 3.3 mesh generation solutions by using the numerical methods demand accurate meshing for the geometry. the quality for the mesh depending on the accuracy for the solution of the numerical. the precision of numerical solution depending on the mesh size. the smaller mesh size needed to produce more accuracy result. the reduction mesh size need more computer memory and processing time. fig. 3. 2d meshing of convergent duct. table 1, meshing characteristics. 3.4 boundary condition the performance inlet conditions and the design choices of the present study were set basing on experience. boundary condition for convergent duct wind turbine summarized in table (2). fig. 4. 2d boundary condition for ducting vertical axis wind turbine. table 2, boundary conduction statistics nodes 67582 elements 66704 mesh metric skewness min 2.4379e-005 max 0.67156 average 6.1832e-002 standard deviation 6.7663e-002 viscous model model k-omega k-omega sst model constants default inlet boundary condition type inlet velocity velocity magnitude(m/s) 10 reference frame absolute turbulent method specification ratio of intensity and viscosity out let boundary condition type pressure outlet gage pressure(pa) 101325 back flow direction specification method normal to boundary turbulent specification method magnitude normal to boundary abdullateef a. jadallah al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 141148 (2018) 144 3.5 turbulence in this study modeled sst (k-@ used for wall bounded turbulent flow around the vertical axis wind turbine the two equation of sst (k-@ turbulent model is: [16] a��b ac + ad�efbg a�f =ph�@i aj�klmnko pn pqfr a�f … �12 a��b ac + ad�efbg a�f = s tcp h ∗ �@? aj�klmuko pnpqfr a�f +2(1 v� �muw a�b a�f … �13 3.6 reference values chord length = 0.1 m reference length = radius of the rotor = 0.5 m. enthalpy = 0 jule /kg pressure = 101325 pa at the velocity inlet density = 1 kg/my temperature = 288.16 k 4. result and disscusion the convergent duct is firstly designed to attain the desired velocity at the inlet of turbine. the duct is converged by 12° and 20° angles. the velocity is increased by 47% and 50% respectively shown in figure (5). however, the static pressure decreases in both cases the benefit of enhanced velocity was achieved as shown in figure (6). the velocity contours show that velocity at the inlet duct equal 10 m/s, it increases gradually until the turbine entry as shown in figures (7&8). this increase in speed causes an increase in the rotation speed of turbine. this will increase the power and power coefficient of the wind turbine. figure (9) and (10) show the pressure contour pressure being to reduce at the convergent duct between the inlet duct and the out let of the duct. the maximum pressure at the inlet duct this gradually decreased toward the throttle. the high energy that can be obtained from the feathers is due to the height of the lifting coefficient, which is produced by the pressure differential on both sides of the wing. figure (11) show the power coefficient against tip speed ratio calculated by ansys. to describes how to use wind energy and convert it into turbine power through a factor called a performance factor. performance coefficient the wind turbine depends on the type of airfoil, the thickness of the blade and the reynold number. figure (12) reveals the power coefficient with tip speed ratio for different inlet angle 12° , 20 °. respectively. results showed that the larger the converging angle, the higher is the power coefficient cp at a certain range of tsr. this is because the increase in the velocity with increase the inlet angle of the duct system. the power coefficient enhanced at a tip speed ratio equal 1.5 for convergent duct when the converging angles 12° , 20 ° by 25.8%, 33.33% respectively. figure (13& 14) show a little difference in the power coefficient value between analytic and numerical solution this difference. this is due to the limitation in numerical solution and that 2d solution does not take into account secondary flow and vortex generated at tip. pressure and velocity distribution along 3d blade there for a good agreement is observed for all cases. 5. conclusions utilization of wind turbines with different configurations are facing the restriction of intermittent and low wind speed. ducted system; convergent, divergent and convergent divergent even with reflectors were employed to enhance the productivity of wind turbines. in this paper, a convergent duct with two converging angles are considered. it was concluded that, increasing the angle of convergence lead to enhance the productivity of the wind turbine regarding less to the drop-in pressure because of the dependency of power on the cubic wind speed. this privilege assist installing wind turbine system in converging gates of buildings and in manufactured adapted ducts and consequently alleviating the use of dawt systems in low wind speed regimes like iraq. fig. 5. velocity distribution along the different convergent duct . abdullateef a. jadallah al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 141148 (2018) 145 fig .6. pressure distribution along the different convergent duct . fig. 7. velocity distribution along the convergent duct inlet angle 12° . fig. 8. velocity distribution along convergent duct inlet angle 20° . fig. 9. pressure distribution along convergent duct inlet angle 12° . fig. 10. pressure distribution along convergent duct inlet angle 20° . fig. 11. power coefficient for convergent duct wind turbine with tip speed ratio. fig. 12. power coefficient for convergent duct wind turbine with tip speed ratio. fig. 13. power coefficient for convergent duct wind turbine with inlet angle 20° . abdullateef a. jadallah al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 141148 (2018) 146 fig. 14. power coefficient for convergent duct wind turbine with inlet angle 12° . greek letters ϕ duct angle [degree] ε turbulent dissipation rate[m? sy⁄ ] ρ air density [kg / m3] / tip speed ratio (tsr) ω the angular velocity [rad/sec] abbreviations cfd computational fluid dynamics si conventional savonius rotor sii first modified savonius rotor siii second modified savonius rotor vawt vertical axis wind turbine tsr tip speed ratio cvawt convergent vertical axis wind turbine con convergent duct 6. references [1] t. saravana kannan, saad a. mutasher utasher, y.h. kenny lau, "design and flow velocity simulation of diffuser augmented wind turbine using cfd "journal of engineering science and technology vol. 8, no. 4 (2013) 372 – 384 [2] r. a. kishore, t. coudron, and s. priya , "small-scale wind energy portable turbine (swept)", journal of wind engineering and industrial aerodynamics, vol . 116, 2013, 2131. [3] andy grant, nick kelly," the development of a ducted wind turbine simulation mode", energy systems research unit, university of strathclyde, scotland, pp. 407–414, 2003. [4] abdullateef a., dhari y. and hayder a.;” performance evaluation of the vertical axis wind turbine with various rotor geometries”; al-qadisiyah journal for engineering sciences, vol. 9; no. 4, 2016. [5] c.j. lawn," optimization of the power output from ducted turbines ", proceedings of the institution of mechanical engineers part ae power & energy, vol. 217, 2003, pp. 107e118. [6] m. shives, c. crawford; "developing an empirical model for ducted tidal turbine performance using numerical simulation results"; proc. inst. mech. eng. parta j. power energy226(1)(2012)112e125,http://dx.doi.org/ 10.1177/ 0957650911417958. issn 09576509. [7] b. kosasih, a. tondelli," experimental study of shrouded micro-wind turbine",procedia. eng. 49(2012)92e98, http://dx.doi.org/10.1016/j.proeng.2012.10.16.i ssn18777058. [8] s.a.h. jafari, b. kosasih;"flow analysis of shrouded small wind turbine with a simple frustum diffuser with computational fluid dynamics simulations"; j. wind eng. ind. aerodyn.125(2014)102e110,110, http://dx.doi.org/10.1016/j.jweia.2013.12.001. issn 01676105. [9] j.n. s ّ◌rensen,"aerodynamic aspects of wind energy conversion ", annu. rev. fluid mech. 43 (2011)427e448, http://dx.doi.org/10.1146/annurevfluid122109-160801.issn 0066-4189. [10] p. mycek, b. gaurier, g. germain, g. pinon, e. rivoalen," experimental study of the turbulence intensity effects on marine current turbines behavior part i: one single turbine",renew.energy66(2014)729e746,htt p://dx.doi.org/10.1016/j.renene.2013.12.036 .issn 09601481. [11] l.j. vermeer, j.n. s ّ◌rensen, a. crespo," wind turbine wake aerodynamics, prog", aerosp.sci.39(6e7)(2003)467e510,http://dx.d oi.org/10.1016/s03760421(03)00078-2. issn 03760421. notation a area [^?] cp power coefficients ct torque coefficients d1 inlet diameter of duct [m] d2 out let diameter of duct [m] k turbulent kinetic energy [^? _`a?⁄ ] l duct length [m] ( pressure (pa) r turbine radius [m] t time [sec] b free stream velocity [ m/sec] abdullateef a. jadallah al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 141148 (2018) 147 [12] d.a. howey, a. bansal, a.s. holmes," design and performance of a centimeter scale shrouded wind turbine for energy harvesting ", smart mater. struct. 20 (8) (2011), http://dx.doi.org/10.1088/09641726/20/8/085021. issn0964e1726. [13] hansen, m.o.l., s ّ◌rensen, n.n., flay, r.g.j., 2000, "effect of placing a diffuser around a wind turbine ", wind energy 3, 207–213, [14] [14] patrick h. oosthuizen , william e. carscallen, " introduction to compressible fluid flow, second edition2nd edition , 2013, isbn-13: 978-1439877913. [15] h. e. saber, e. m. attia, h. a. el gamal," analysis of straight bladed vertical axis wind turbine". international journal of engineering research & technology (ijert) issn: 2278-0181 ijertv4is070453 www.ijert.org (this work is licensed under a creative commons attribution 4.0 international license.) vol. 4 issue 07, july-2015 [16] launder b. e. and spalding d. b.," lectures in mathematical models of turbulence", academic press, london, england. 1972. )2018(141-148 ، صفحة3، العدد14دجلة الخوارزمي الهندسية المجلم جاد عبد اللطيف احمد 148 بيتعزيز أداء التوربين الريحي عمودي محور االدارة باستخدام منظومة معبر هواء تقار ***جنان دخيل حمدي **سحر راضي فرج *عبد اللطيف أحمد جاد هللا العراققسم الهندسة الكهروميكانيكية /الجامعة التكنولوجية / بغداد / *،**،*** abdullateef.aljad@gmail.com*البريد االلكتروني: dr saharalsakini@yahoo.com*البريد االلكتروني: jenanjenan780@yahoo.com :البريد االلكتروني*** الخالصة استخدام أجريت دراسات عديدة لتحسين اداء التوربين الريحي العمودي. تناول هذا البحث دراسة تحسين اداء التوربين الريحي عمودي محور االدارة ب لتمكين حساب معامل القدرة والعزم والمتغيرات الحاكمة االخرى ansys 17.2معبر هوائي تقاربي. تم تطويع منهجية رياضية تحليلية وعددية باستخدام %٣٣٫٣٣و %٢٥٫٨ان استخدام المعبر بالزاويتين المذكورتين آنفا حقق زيادة في معامل القدرة بواقع . ه ٢٠و ه ١٢باستخدام زاويتين لمعبر الهواء وبواقع ن الحل العددي ومقارنته بنتائج الحل التحليلي واظرهت تطابقا جيدا.على التوالي. تم تمثيل تصرف الجريان وحساب معامل القدرة م <4d6963726f736f667420576f7264202d20dae3c7cf20e6dac8c7d320e6c7cdd3c7e4203131382d313237> al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 14, no. 1, march, (2018) p.p. 118-127 study the effect of welding heat input on the microstructure, hardness, and impact toughness of aisi 1015 steel emad kh. hamd* abbas sh. alwan** ihsan khalaf irthiea*** *,*** engineering college/ university of anbar/ iraq ** agriculture college/ university of baghdad/ iraq emkh7676@gmail.com*email: drabbasshalwan@gmail.com**email: ***email: ih77san@yahoo.co.uk (received 17 may 2017; accepted 31 august 2017) https://doi.org/10.22153/kej.2018.08.005 abstract in the present study, mig welding is carried out on low carbon steel type (aisi 1015) by using electrode er308l of 1.5mm diameter with direct current straight polarity (dcsp). the joint geometry is of a single v-butt joint with one pass welding stroke for different plate thicknesses of 6, 8, and 10 mm. in welding experiments, aisi 1015 plates with dimensions of 200×100mm and edge angle of 60o from both sides are utilized. in this work, three main parameters related to mig welding process are investigated, which are welding current, welding speed, heat input and plate thickness, and to achieve that three groups of plates are employed each one consists of three plates. the results indicate that increasing the weld heat input (through changing the current and voltage) leads to an increase in widmanstatten ferrite (wf), acicular ferrite (af) and polygonal ferrite (pf) in fz region, and a reduction in grain size. it is observed that the micro-hardness of welded aisi 1015 plate increases as the weld heat input decreases. as well as increasing the weld heat input results in an increase in the width of wm and haz and a reduction in the impact energy of the weld joint of aisi 1015 at wm region. also, it is noted the corrosion rate of weld joint increases with increase of icorr due to increasing in welding current (heat input), corrosion rate increased up to (0.126µm/yr.) with increasing of heat input up to (1.27 kj/mm). keywords: heat input, impact trength, mig welding, micro-hardness. 1. introduction numerous welding systems are utilized to create fabricated assemblies that may not seem to incorporate welding by any means. welding additionally has key applications for the repair of basic structural assemblies. welding procedures are advantageously separated into two classes: fusion welding and solid state welding [1]. the high temperature associated to fusion welding may cause entrapping some oxides in the weld metal and this action in turn degrade the mechanical properties and corrosion resistance of the weld joint. in all electric arc welding processes, a gaseous shield is therefore created around the weld zone to protect it from surrounding atmosphere [2-3]. it is found that the process key parameters of metal inert gas (mig) have a crucial influence on the quality, productivity and cost of welding joints [4-6]. mig welding process overcome the constraint of using small lengths of electrodes as in manual metal arc welding and overcomes the incapability of the submerged arc process to weld in a number of positions. it is not surprising, therefore, that the 50/50 level of the relative weights of weld metal deposited by manual metal arc and mig processes was reached in 1973 in the usa and in 1978 in europe [7]. emad kh. hamd al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 118127 (2018) 119 reverse polarity (positive electrode) is used for most mig welds. this arrangement offers more stable arc than the straight polarity arrangement, and faster welding speeds are possible. the latter results from electrons striking the consumable electrode (welding wire) which is more rapidly melted and deposited into the joint area. moreover, as mig welding includes the transfer of metal droplets from the electrode to the base metal, relatively deeper penetration is acquired with reverse polarity. if straight polarity is used, the large positive ions travelling toward the electrode tend to support the metal droplets, which results in shallow weld penetration. conversely, the metal droplets are subjected to a significant downward force by the large positive ions when reverse polarity is used, which results in greater depth penetration [1]. this work presents an experimental investigation on the effect of some mig process parameters such as weld heat input, weld current and weld speed on the microstructure (grain size), microhardness, and impact resistance of mig weldment. 2. experimental work 2.1. materials in the current work plates of low carbon steel (aisi-1015) are used as base metal for the welding processes. the experimental chemical composition of the material and the standard composition of aisi-or sae 1015 according to (swe) are shown in table 1. the standard mechanical properties of the aisi 1015 carbon steel are displayed in table 2. table 1, the chemical composition of low carbon steel table 2, the standard mechanical properties of the aisi-1015 [8] properties condition hf cf tensile strength (mpa) 324 365 yield strength (mpa) 179 303 elongation (in 2 in. %) 28 20 2.2. experiment procedure the plates of low carbon steel with dimensions of (200 mm long × 100 mm width, with different thicknesses were prepared by milling machine from both surfaces and vsingle butt joint is designed by machining the specimen to angle (60o) from both sides as shown in fig. 1. nine samples of weldments at different parameters were prepared as shown in table 3. plate thickness of specimens 7, 8 and 9 with thickness 6, 8 and 10mm respectively. metal inert gas welding (mig) process is executed using consumable electrode er308l austenitic stainless steel of diameter (1.5mm) conforms to certification: aws a5.9/asme sfa a5.9, it contains low carbon content and this help to prevent the intergranular corrosion. mig welding machine used in this work was type (esab), ideal arc dc-600-lincoln companysweden. mig welding is carried out with one pass, and an electrode er308l of diameter (1.5mm). a stop watch was used to record the welding time. all samples for microstructure prepared after cutting and sic emery paper of grade 120, 320, 500, 1000, and 1200. slurry of al2o3 particles of size of 5µm were used for polishing process, with a special cloth. etching process was carried out using nital solution consisting of 2% nitric acid (hno3) and 98% of alcohol. the optical microscopy type rgh, with digital camera connected to the computer at magnification ×200 is used for microstructure examination. j-image software and linear intercept method are used to measure the average grain size. the heat input (kj/mm) is calculated by equation: (q=η× (vi/v) (η=0.7) …(1) element c% si% mn% p% s% cr% measured wt.% 0.148 0.065 0.537 0.016 0.004 0.0033 mo% ni% al% cu% fe% ˂0.002 0.055 0.054 0.071 bal. standard aisi 1015 [8] c% mn% p. max% s. max% fe% 0.13-018 0.3-0.6 0.04 0.05 bal. emad kh. hamd al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 118127 (2018) 120 microhardness test by using digital microhardness tester type (qv-100-qualitest company-japan). microhardness traverses 1mm (the distance between two readings), were produced across the weld regions using a 1000g load and a 10sec dwell time. to conduct the impact test, firstly test piece is prepared based on standard astm a370, (the standard specimen size for charpy impact testing is (10mm×10 mm×55 mm). the energy toughness values are recorded to evaluate the effect of heat input on the impact strength of weldments as shown in table 4. fig. 1. single v-joint design of plate. table 3, experimental welding conditions of mig welding. table 4, welding parameters of weldments for impact test. 3. results 3.1. effect of weld speed on microstructure increasing welding speed results in decreasing heat input as shown in fig. 2. the effect of heat input is to decrease grain size of weld metal (wm) and heat affected zone (haz), but no effect on grain size of base metal. increasing of welding speed (decreasing of heat input) cause a little decrease of ferrite grain size about 11% as a decreasing percentage as shown in table 5, due to increasing the cooling rate. the microstructure of weld metal (fz) is consisting mainly of acicular ferrite (af), widmanstatten ferrite (wf) and polygonal ferrite (pf), and refine with increase the welding speed (decrease heat input) as shown in figs. 3, 4 and 5. also, the microstructure of haz grains are also refined with decreasing heat input. from table 5, the grain boundary is also affected by cooling rates (heat input) which depend on welding parameters such as welding current and speed. when increase the welding speed leads to a slight decrease in grain size in fz and haz, but the grain size of bm has not affected. grain refinement is resulted at lower heat input (faster cooling rate).this is in agreement with the reference [9]. variables specimen 172.413 speed welding (v) (mm/min) 1 150.37 2 100 3 180 current welding (i) (ampere) 4 190 5 210 6 6 plate thickness (t) (mm) 7 8 8 10 9 specimen code. plate thickness (mm) welding current (amp) welding voltage (volt) welding speed (mm/min) heat input (kj/mm) a 10 220 20.7 150.37 1.2719 b 10 240 21.7 150.37 1.4546 c 10 260 23 150.37 1.6702 emad kh. hamd al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 118127 (2018) 121 table 5, calculation result of heat input and grain size with different welding conditions. width (mm) grain size (µm) heat input (kj/mm) specimen haz fz bm haz fz 4 4 20.19 17 16.85 0.826 1 3.5 4.5 17.82 17 0.945 2 3.5 5 18.85 18.94 1.428 3 3.5 4 12 11.77 0.763 4 4 4.5 13.47 14.27 0.805 5 5 5 17.24 20.6 0.889 6 2 3 11.2 10.68 1.2719 7 3 3.5 12.7 12.44 1.6408 8 3.5 4 12.3 14.77 2.5116 9 fig. 2. the relationship between heat input and welding speed at 170 amp and 20 volt. (a) fz (b) haz (c) bm fig. 3. microstructure of butt joint of specimen 1 at i: 170amp, v: 20volt, s: 172.413mm/min and heat input: 0.826 kj/mm, (×200). (a) fz (b) haz fig. 4. microstructure of butt joint of specimen 2 at i: 170amp, v: 20volt, s: 150.37mm/min and heat input: 0.945 kj/mm, (×200). wf pf af wf af pf emad kh. hamd al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 118127 (2018) 122 (a) fz (b) haz fig. 5. microstructure of butt joint of specimen 3 at i: 170amp, v: 20volt, s: 100mm/min and heat input: 1.428 kj/mm, (×200). 3.2. effect of weld current on microstructure it is observed that the heat input increases with the welding current as shown in fig. 6. a columnar grain was course as seen in the weld metal (fusion zone). therefore, an increase in the welding current leads to increase grain size as shown in table 5. an increase in welding current effect on increase of the grain size in both fz and haz regions. this variation in grain size due to the effect of cooling rates. the microstructure of fusion zone consists of fine acicular ferrite (af), widmanstatten ferrite (wf) and some inclusions as shown in figs. 7 and 8. the size of haz region grains increases with increasing welding current (increase heat input) as illustrated in table 5. the increase in welding current causes the heat generated to increase resulting the polygonal ferrite grains in fz to recrystallized and grow as presented in fig. 9. fig. 6. the relationship between heat input and welding current at welding speed 200mm/min, and welding voltage 20.2volt. (a) fz (b) haz fig. 7. microstructure of butt joint of specimen 4 at i: 180amp, v: 20.2volt, s: 200mm/min and heat input 0.763 kj/mm, (×200). wf af wf af inclusion emad kh. hamd al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 118127 (2018) 123 (a) fz (b) haz fig. 8. microstructure of butt joint of specimen 5 at i: 190amp, v: 20.2volt, s: 200mm/min and heat input 0.805 kj/mm, (×200). (a) fz (b) haz fig. 9. microstructure of butt joint of specimen 6 at i: 210amp, v: 20.2volt, s: 200mm/min and heat input 0.889 kj/mm, (×200). 3.3. effect of weld speed on microhardness concerning the effect of welding speed on microhardness at welding current 170amp and welding voltage 20.2v, the microhardness distribution in different zones; weld zone (fz), heat affected zone (haz) and base metal (bz) is shown in fig. 10. the microhardness values of 166.6231 hv are observed at location within 1 mm from the base metal, through the haz across the weld metal. from the figure, it can be seen that the microhardness values increase with increasing welding speed. this is attributed to increase the cooling rate and decrease the grain size. this is in agreement with hardness results of zhang and roy [9]. besides, the maximum microhardness of wm is 201, 212 and 231 hv with welding speed 100, 150.37 and 172.413 mm/min, respectively. width of fz and haz regions, were affected by heat input with various welding speeds. table 5 shows the increase of width of fz and the decrease of width of heat affected zone haz with the decrease of welding speed. 3.4 effect of weld current on microhardness concerning the effect of welding current on microhardness at welding speed 200 mm/min and welding voltage 20.2 volt, the microhardness distribution in different zones; weld zone (fz), heat affected zone (haz) and base metal (bz) is shown in fig. 11. the microhardness values of 166.6-247 hv are observed at location within 1 mm from the base metal, through the haz across the weld metal. these hardness results are partially in good agreement with literature. güral, et al. [15], have found that maximum hardness values are measured in the area of weld metal (fz). nevertheless, in the present work, the maximum hardness is both in weld metal (fz) and heataffected zone (haz). the variation in properties across the weld can be attributed to several issues, essentially to residual stresses just created after welding. welding current is the most significant factor, which effected on the microhardness. the hardness decreases with increasing the welding current (heat input) which increases the width of wm and haz regions as shown in fig. 11 and table 5. this is due to the decrease of cooling rates when increasing welding current and this effect turns to decrease in the microhardness of the welded joint. this is as result of increasing of the grain size i.e. coarser grain in haz region. the microhardness reaches maximum value 203hv at the middle of weld metal fz and drops gradually to the base metal 166.6hv. pores inclusion emad kh. hamd al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 118127 (2018) 124 3.5 effect of plate-thick on microhardness plate thickness plays the essential role in the effects on microhardness. fig. 12 shows the microhardness distribution in different zones; weld zone (fz), heat affected zone (haz) and base metal (bm) at different welding current and welding voltage. the microhardness values of 167 253 hv in fig. 12 are observed at location within 1mm from the base metal, through the haz across the weld metal. it is observed that the microhardness values decrease as plate thickness increases because of drop in the cooling rate and the increase in grain size of wm and haz. the peak microhardness value is 219, 212 and 208hv in haz region, respectively with increase of thickness. in addition, the width of haz is affected by plate thickness, where bigger haz width about 3.5mm was obtained at thickness (10mm), this is attributed to higher weld heat input; slower cooling rate [17], as compared with other plates. width of fz and haz regions, were observed table 5, it shows an increase of width of fz and heat-affected zone haz with the increase of plate thickness. 3.6. effect of heat input on impact resistance to evaluate the effect of heat input developed during the mig welding at different parameters, on the impact strength, a set of three specimens is selected and the results of absorbed energy that obtained from the testing machine were tabulated in table 6. in this table, it can see that an increase in heat input leads to drop in cooling rate [18] and it gives an effect of decreasing the impact strength within this value of current as shown in fig. 13. from the experiments, it is shown that for the range of current 220-260ampere, the impact strength of the weld and heat affected zone of the weld joint reduces. as a result, the higher heat input, the lower impact toughness value, this in agreement with literature [19]. fig. 10. effect of welding speeds on microhardness at welding current 170 amp and welding voltage 20v. fig. 11. effect of welding current on microhardness at welding speed 200mm/min and welding voltage 20.2volt. fig. 12. effect of plate thickness on microhardness at different welding current and welding voltage. emad kh. hamd al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 118127 (2018) 125 table 6, impact test results with plate thickness 10mm at welding currents (220, 240 and 260 ampere). specimen code. heat input (kj/mm) impact energy (j) a 1.2719 61.74 b 1.4546 54.4 c 1.6702 49.17 fig. 13. the relationship between impact energy and heat input at different welding parameters. 4. conclusions 1. it is found that formation of phases; acicular ferrites (af), widmanstatten ferrites (wf) and polygonal ferrites (pf) in weld metal (wm) are affected by weld heat input. 2. increasing welding current leads to increment in the heat input, this leads to a reduction in cooling rate, then increases the grain size of weld metal (wm) and heat affected zone (haz) and decreases the microhardness of the welded joint. 3. increasing the welding speed, decreases the heat input (i.e. increases the cooling rate) which leads to increase the microhardness in wm and haz regions, decreases grain size in wm and haz regions.. 4. increasing plate thickness leads to increase the heat input and reducing the cooling rate, this leads to increase the grain size of wm and haz regions and decrease in the microhardness values. 5. impact strength of the weld metal and heat affected zone haz of the weld joint reduces with increasing of heat input. 5. notation q heat input (j/mm) i welding current (ampere) v welding voltage (volt) s welding speed (mm/min) n order of diffraction d inter planer spacing distance (ao) icorr corrosion current (μa/cm2) ecorr corrosion potential (mv) c.r corrosion rate (mm/year) w equivalent weight (grams) r2 coefficient of determination fz fusion zone haz heat affected zone wm weld metal bm base metal af acicular ferrite wf widmanstatten ferrite pf polygonal ferrite mig metal inert gas welding mmaw manual metal arc welding aws american welding society ms martensite start mf martensite finish cf cold finishing hf hot rolled greek letters η welding efficiency (℅) λ wave length (ao) θ diffraction angle (degree) ρ density (g/cm3) 5. references [1] the procedure handbook of arc welding, 14th edition, the james f. lincoln arc welding, 2000. [2] gourd lm, principles of welding technology, 3rd edition. edward arnold, 1995. [3] j. beddoes & m. j. bibby, “principles of metal manufacturing processes”, carleton university, canada, 1999. [4] j. puchaicela, “control of distortion of welded steel structures”, welding journal, pp.49-52, 1998. [5] kim is, sona js, kim ig, kim jy and kim os., “a study on relationship between process variables and bead penetration for robotic co2 arc welding”, j. mater. process. technol. 136, pp. 139–145, 2003. emad kh. hamd al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 118127 (2018) 126 [6] han guoming, yun shaohui, cao xinhua, li junyue, “acquisition and pattern recognition of spectrum information of welding metal transfer”, j. mater. & design, 24, 699–703, 2003. [7] welding handbook volume 4, “metals and their weldability”, american welding society (asm), seventh. [8] rechard s.sabo,"the procedure handbook of arc welding ", the lincolin electric company, cleveland, ohio44117, australia, 1999. [9] zhang. w. and g.g.roy, "modeling of heat transfer and fluid flow during gas tungsten arc spot welding of low carbon steel", journal of applied physics, march , , vol. 93, no. 5, 2003. [10] ueji, r., fujii, h., cui, l., nishiokioka, a., kunishige, k. and nogi, k., “friction stir welding of ultrafine grained plain lowcarbon steel formed by the martensite process”, materials science and engineering: a, 423, 324330, 2006. http://dx.doi.org/10.1016/j.msea.2006.02.038 [11] easterling, k.e., “modeling the weld thermal cycle and transformation behavior in the heat affected zone”, in: cerjak, h. and easterling, k.e., eds., mathematical modeling of weld phenomenon, the institute of materials, 1998. [12] marashi, p., pouranvari, m., amirabdollahian, s. and abedi, g., “microstructure and failure behavior of dissimilar metal spot welds between low carbon steel, galvanized and austenistic stainless steels. materials science and engineering: a, 420, pp. 175-180, 2008. http://dx.doi.org/10.1016/j.msea.2007.07.00 7 [13] g. r. stewart, a. m. elwazri, r. varano, n. pokuty-lowicz, s. yue and j. j. jonas, “shear punch testing of welded pipeline steel,” materials science and engineering a, vol. 420, no. 1-2, , pp. 115-121, 2006. [14] s. lars-eric, “control of microstructures and properties in steel arc welds,” library of congress catalog-ing-in-published data, british, 1994. [15] a. güral, b. bostan and a. t. özdemir, “heat treatment in two phase region and its effect on welding of a low carbon steel,” materials and design, vol.28, no. 3, pp. 897903, 2007. [16] gery, h., long, p. and maropoulos, e., “effects of welding speed, energy input and heat source distribution on temperature variations in butt joint welding”, journal of material processing technology, 167, pp 393401, 2005. http://dx.doi.org/10.1016/j.jmatprotec.2005.06 .018 [17] david s.a, s.s.babu, & j.m.vitek,"welding solidification and microstructure", oak ridge national laboratory, vol. 32, no. 3, 2003. [18] odd m.akselsen, ragnhild and vigdis olden," effect of phase transformations on residual stresses in welding of stainless steel", international journal of offshore and polar engineering (issn 1053-5381), vol. 17, no. 2, pp. 145–151, 2007. [19] wan shaiful hasrizam wan muda, nurul syahida mohd nasir, sarizam mamat and saifulnizan jamian, "effect of welding heat input on microstructure and mechanical properties at coarse grain heat affected zone of abs grade a steel", arpn journal of engineering and applied sciences, vol. 10, no 20, pp. 94879495, 2015. )2018( 118-127، صفحة 1د، العد14دجلة الخوارزمي الهندسية المجلم عماد خميس حمد 127 لفوالذ متانة ال، الصالدة، وعلى البنية المجهريةتأثير الحرارة المتولدة اثناء اللحام دراسة aisi 1015 احسان خلف رثيع*** عباس شياع علوان** عماد خميس حمد* *،*** كلية الهندسة/جامعة االنبار الزراعة/جامعة بغداد** كلية emkh7676@gmail.com :البريد االلكتروني* drabbasshalwan@gmail.com:البريد االلكتروني** ih77san@yahoo.co.uk :البريد االلكتروني*** الخالصة ملم) ١٫٥باستخدام سلك لحام قطره ( (aisi 1015) في الدراسة التجريبية هذه، تم استخدام اللحام الغازي المعدني الخامل للحام فوالذ منخفض الكربون بتمريرة (v) والقطبية المطبقة قطبية مباشرة ذات تيار مباشر من قطب اللحام الى الوصلة، وتم لحام وصلة تناكبية على شكل الحرف (er308l) نوعه ملم) ١٠٠× ملم ٢٠٠صفائح من الفوالذ الكربوني ذات ابعاد ( ملم). تضمن الجانب العملي لهذه الدراسة، تحضير ١٠و ٨، ٦واحدة عند اسماك مختلفة ( ) من كال جانبي وصلة اللحام، تم لحام وصالت اللحام المعدة عند متغيرات مختلفة وهي: تيار اللحام، سرعة اللحام والحرارة ٦٠oوحواف ذات زاوية ( ات كل منها يضم ثالث عينات.المتولدة وسمك وصلة اللحام. تم اجراء اللحام لثالث مجاميع من العين جوانب في منطقة النتائج بينت ان الزيادة في الحرارة المتولدة اثناء اللحام تعمل على زيادة بنية فرايت فيدمنشتاتن والفرايت االبري وفرايت متعدد ال ضا لوحظ زيادة الصالدة المايكروية مع نقصان الحرارة اللحام االنصهاري، ونقصان الحجم الحبيبي نتيجة معدل التبريد السريع (حرارة متولدة اقل). وأي لصدمة لوصلة الفوالذ المتولدة اثناء اللحام، وزيادة في عرض منطقة اللحام والمنطقة المتأثرة بالحرارة مع زيادة الحرارة المتولدة اثناء اللحام. مقاومة ا جول) نتجت عند اعلى حرارة ٤٩٫١٧تولدة اثناء اللحام، حيث ان اقل طاقة صدمة (الكربوني منخفض الكربون في منطقة اللحام تقل بزيادة الحرارة الم كيلوجول/ملم). ٢٫٣٨٦متولدة ( ً ان معدل التآكل لوصلة اللحام يزداد بزيادة تيار التآكل نتيجة الزيادة الحاصلة في تيار اللحام (زيادة الحرارة المتولدة) ، بمعنى آخر فأن لوحظ ايضا لوصلة اللحام تقل بزيادة كمية الحرارة المتولدة اثناء عملية اللحام. مقاومة التآكل <4d6963726f736f667420576f7264202d20ddc7d6e120e6c7dfd1e320e6d5c7c8d1ede439392d313037> physical and morphological properties of hardsoft ferrite functionally graded materials fadhi chyad* akram jabur** sabreen abed*** *, **,***department of materials engineering/university of technology/ iraq *email: fchyad_2009@yahoo.de **email: akram.jabut@gmail.com ***email:sabreenali217@gmail.com (received 20 december 2016; accepted 31 october 2017) https://doi.org/10.22153/kej.2018.10.007 abstract functionally graded materials (fgms), with ceramic –ceramic constituents are fabricated using powder technology techniques. in this work three different sets of fgms samples were designed in to 3 layers, 5 layers and 7 layers. the ceramic constituents were represented by hard ferrite (barium ferrite) and soft ferrite (lithium ferrite). all samples sintered at constant temperature at 1100oc for 2 hrs. and characterized by fesem. some physical properties were measured for fabricated fgms include apparent density, bulk density, porosity, shrinkage and hardness. the results indicated that the density increase with the increase the number of layer. lateral shrinkage is one of the important parameter for estimating the quality of component gradation in an fgm structure. the vickers hardness show higher value at fgm7, finally the fesem images showed a gradation in microstructure within the system from platelike structure for the hard ferrite to spherical structure for the soft ferrite. keywords: functionally graded materials; physical properties of fgm; ceramic; hard ferrite; soft ferrite. 1. introduction in the previous couple of years, the usage of ceramic materials has amazingly expanded in various applications in view of the particular properties of these materials in examination with metals and polymers. the gainful qualities of ceramic materials are hardness, inflexibility, grating durability and low thickness. ceramics are a sort of materials by and large characterized as "inorganic, nonmetallic solids". they have the colossal degree of motivation behind every single known material. the most recent decades have seen the advancement of the tremendous capability of practical earthenware production in light of interesting dielectric, ferroelectric, piezoelectric, pyro-electric, ferromagnetic, magneto-resistive, ionical, electronical, superconducting, electrooptical, and gas-detecting properties. similar logical extensions additionally have occurred in auxiliary ceramic. thermal, chemical, and mechanical steadiness of numerous oxide and nonoxide mixes have put the reason for improved handling, which prompted an upgraded level of microstructure outline and flaw control. this has progressively directed in at no other time seen improvements in mechanical conduct and in the precision of the properties of parts and devices [1]. ferrites are categorized mainly into three sets with various crystal types. they are spinel, garnets and magneto-plumbite. spinel ferrites have a cubic structure with general equation mo fe2o3, where m is a divalent metal particle, similar to mn, ni, fe, co, mg, and so forth. garnets have a complex cubic structure having a general equation m3fe5o12. the third sort, magneto-plumbite, has a hexagonal structure with general recipe mo. fe12o18. the most critical in the arrangement of magneto plumbite is barium ferrite bao fe12o18, which is a hard ferrite [2]. the quick advancement of new al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 14, no. 1, march, (2018) p.p. 99-107 fadhi chyad al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 99107 (2018) 100 high innovation requests an ever increasing number of new materials with various uncommon attributes or capacities. under some serious boundaries, for example, super high temperature, conventional materials may not serve. another material idea, practically evaluated materials (fgms), has been proposed to meet the prerequisite which typically incorporate diverse material constituents, for example, ceramic and metal. fgms have received significant attention in many engineering applications since they were first outlined in 1980s. they are composite materials, microscopically inhomogeneous, in which the mechanical properties change smoothly and continuously from one surface to the other. compared with classical laminated composite materials, fgms supply outstanding thermo-mechanical performances under given loading conditions. fgms can be utilized to enhance creep behavior, fracture toughness of machine tools, wear resistance, oxidation resistance of high temperature aerospace and automotive components and so on .[3] (jaworska, et.al.2006) studied functionally graded cermets. materials were acquired using free sintering at vacuum and the high temperature-high weight sintering system. practically evaluated cermets have greater amount of hard stage in the surface layer and lower cooperation of this stage in the body outline. fgms were set up by the layers pressing operation and the diffusive statement operation. material with 55 wt.% of tic and 45 wt.% of (ni,mo) was incorporated. the stage's structure of this material was analyzed. (shabana,et.al.2006) modeling the development of stress because of differential shrinkage in powderprocessed functionally graded metal–ceramic composites during pressureless sintering. this model can be used to decide helpful shrinkage rates and slope structures for a given segment geometry that will restrict the part from breaking amid pressureless sintering by adjusting the advancement of quality, which should be a power law capacity of the porosity, with the improvement of stress. to estimate this model, the powder blend is evaluated as a three-stage material including voids, metal particles, and artistic particles. a micromechanical thermal elastic– viscoplastic constitutive model is then proposed to show the thermomechanical conduct of the composite microstructure. (shahrjerdi,et.al.2011), demonstrated the functionally graded metal-ceramic composite synthisized through weight less sintering. the unadulterated metallic and ceramic parts are titanium (ti) and hydroxyapatite (ha), which were situated at the finishes of a round and hollow example. fg tests are set up with blending extents of 100:0, 75:25, 50:50, 25:75, 0:100. the barrel shaped specimens had a thickness of 6 mm in size and 20 mm span. tests are manufactured by utilizing carbon cylindrical die. the ideal thermal load mapping is picked up tentatively. the properties of all fgm items are portrayed by shrinkage, optical magnifying instrument, filtering electron magnifying instrument (sem), vitality dispersive spectrometry (edx) and hardness test. (mahamood,et.al.2012), proposed an overview of synthesizing method , field of application, some new research studies the need to concentrate more research attempt on improving the most promising fgm synthesizing method (solid free form sff). improving the performance of sff processes and extensive studies on material characterization on components produced will go a long way in lower the manufacturing cost of fgm and increase productivity in this respect. (mustapha, et.al.2013), suggested an extensive review on the various synthesizing methods of fgms composed by metallic and ceramic phases. synthesizing methods in this field of work have comprising many concepts from various background of gradation methods and consolidation or sintering methods (yu, et.al.2013) suggested micromechanics display represents multi-stage heterogeneity and discretionary number of layers. the impact of geometries and unmistakable flexible material properties of every constituent and voids on the viable versatile properties of fgm is examined. numerical cases of different practically reviewed materials are introduced. the predicted elastic properties resulted from the present model work in well with experimental results from the literature. (fadhil, et.al.2017) studied dielectric and magnetic properties of nanoferrite functionally graded materials with ceramic –ceramic constituents are fabricated using powder technology techniques. in this work three different sets of fgms sample were designed in to 3 layers, 5 layers and 7 layers. the ceramic constituents were represented by hard ferrite (barium ferrite) and soft ferrite (lithium ferrite). all samples sintered at constant temperature at 1100oc for 2 hr. the magnetic properties showed an increase in coercive force (hc) with increased number of layers. the dielectric properties measured at room temperature with constant frequency 1 mhz. the results showed the dielectric constant increase with the increase the number of layers from (1.39×10-2) to (2.83×10-2). according to the above literature reviewing, it's clear that the fabrication of hard ferrite\lithium ferrite functionally graded materials is a very new fadhi chyad al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 99107 (2018) 101 area for investigation that based on using graded ceramic materials. the aim of this work is fabrication a functionally graded materials (fgms) from hard ferrite and soft ferrite materials in three different set of multiples layers and then studying the physical and morphological properties of the system. 2. experimental procedure 2.1. starting materials nano barium ferrite ( bafe12o19) , nano lithium ferrite (life5o8). 2.2. preparation of hard/ soft functionally graded material the start material used to fabricate fgm sample were nano barium ferrite and nano lithium ferrite, are weighted in the proportions as shown in table (1). the formation of a discrete layered graded structure at first requires mixing of the base materials to appropriate composite powder composition. the fgm structure consists of the two base materials on either end of the specimen, with the desired compositional gradient layered between the two as shown in fig. (1). the fgm system are composed of (3, 5, and 7) layers with thickness (4.5, 8, and 12) mm, respectively. the weight of fgm layer will measured by sensitive balance , the constituents powder were arranged according to the volume fraction of layer starting from lithium ferrite to barium ferrite as mentioned in table (1), after that compacting practice were done under 20000 mpa load pressure. each sample was subjected to sintering under temperature of 1100oc for 2 hr. the sintering heating cycle including a slow heating rate with 5 °c∕ min, (see fig. 2). all sintering practices were carried out by using electric furnace. fig. 1. sketch represents fgm system with 3 lay table1, fgm profil fig. 2. single heating cycle of the applied sintering process. 3. results and discussion 3.1 physical properties 3.1.1 density and porosity the (bulk and apparent) density for fgm sample are shown in fig. (3). porosity for fgm system was also shown in fig. (4). the variation of density between the different fgm sample with (3, 5, 7) layer which shown slightly an increase of density with the increase the number of layer; the reason behind such improvement is related to high densification, high homogeneity and good blending between the layer of fgms [7]. the 3 layer 5 layer 7 layer weight of lim(g) weight of bam(g) total thickness 100% lim 100% lim 100% lim 0.4 0 4mm 80% lim +20%bam 0.32 0.08 75% lim+25% bam 0.3 0.1 65%lim+35%bam 0.26 0.14 7mm 50%lim+50 %bam 50%lim+50%bam 50%lim+50%bam 0.2 0.2 35%lim+65%bam 0.14 0.26 11mm 25%lim+75%bam 25%lim+75%bam 0.1 0.3 100% bam 100% bam 100% bam 0 0.4 fadhi chyad al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 99107 (2018) 102 results of density of prepared fgm sample accompanied by almost slightly increase of porosity at constant sintering temperature. fig. 3. density results of fgm samples of (3, 5, 7) layers. fig. 4. porosity results of fgm samples of (3, 5, 7) layers. 3.1.2. lateral shrinkage lateral shrinkage is one of the important parameter for estimating the quality of component gradation in a fgm structure. figure (5) illustrates the effect of change of the percentages among the layers versus the number of layers of the sample sintered at 1100oc for 2 hours. shrinkage showed an increase in fgm7 as compared with fgm3 and fgm5. the linear shrinkage obtained was an appropriate indicator of the functionality of the design. fig. 5. lateral shrinkage of fgm samples of (3, 5, 7) layers. 3.1.3. micro hardness test microhardness test was carried out to study the gradient of the mechanical property along the fgms thickness. in spite of the fact that the phenomenon of hardness is in general is purely a surface property, which represents its resistance to indentation, but in numerous cases the value of surface hardness may be safely used to indication of the state of compactness and integrity of the bulk. the vickers micro hardness value of fgm sample (3, 5, and 7) layers after sintering practices is presented in figs. (6), (7) and (8) respectively. it is clear that as the barium ferrite percentage increased; the hardness is increased. (fgm 3) seems to give graded hardness properties. also it can be noted that the (fgm 7) layer 7 (100% bam) and layer 1 (100% lim) has the higher value of vickers hardness as compared with (fgm3) and (fgm5) due to increment of density and compacting load. fig. 6. vickers hardness values for fgm 3. fadhi chyad al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 99107 (2018) 103 fig. 7. vickers hardness values for fgm 5. fig. 8. vickers hardness values for fgm 7 3.2. fe-scanning electron microscopy (fesem) analysis field emission scanning electron microscope (fesem) is used to visualize the microstructure of functionally graded materials by scanning with high energy electron beams. fig. (9) shows the microstructure of the fabricated lim\bam fgms. it has three layers: the 1st layer (pure bam) plate like structure with the average size (150-350)nm plus few spherical structure of size (150-200)nm, the 2nd layer mixed both plate of size lightly larger (250400nm)average and spherical of size (400nm) while the 3rd layer (pure lim) is spherical structure of 500 nm average size , respectively. fig. (10) shows the microstructure of the fabricated lim\bam fgms. it has five layers: the 1st layer (pure bam) plate like structur with the average size (150-300) nm, 25lim&75bam, 50lim&50bam, 75lim&25bam (mixed both plate and spherical structure) with the average size (300,700,350) nm, respectively. the 5th layer (pure lim) spherical less porous dense structure with average size (400-1500) nm, respectively. fig. (11) shows the microstructure of the fabricated lim\bam fgms. it has seven layers: the 1st layer (pure bam) plate like structure with average size (250-350)nm,35 lim&65bam plate like thickness range (350-400)nm,50lim &50bam plate more thick (400)nm, 65lim &35 bam plate less thick (250)nm, 75lim & 25 bam nm spherical (250-1000)nm more dense less porous, 80 lim &20 bam spherical (350-1000)nm, the 7th layer (pure lim) spherical structure (more growth, spherical large, less porous), respectively. from the sem images of 3rd layer fgm3 fig.(8c), 5th layer of fgm5 fig.(9e) and 7th layer of fgm 7 fig.(10g) it can be seen the grain patterns exhibited totally sphericallike structure , a clear crystalline structure was also observed. also it can be seen a large growth in size at the 3rd , 5th and 7th layer because of the remaining of one phase and disappearances of the other which use to be suppress the growth at the other layer. in contrast, as shown in sem images of 1st layer fgm3 fig. (8a), 1st layer of fgm5 fig.(9a)and 1st layer of fgm7 fig.(10a) the grain morphology appear totally plate -like shape which is clearly indicated the formation of barium ferrite. barium hexaferrite nanoparticles with plate-like morphology is the best for the electromagnetic wave absorption application [9]. also for the composite layer sem images show the grain microstructure as a combination of spherical and plate like structure which is an evidence for the gradation in fgms samples and resulting in properties variation. fadhi chyad al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 99107 (2018) 104 (a) (b) (c) fig. 9. fe-sem of fgms sample with 3 layers: a) first layer, b) second layer and c) third layer. (a) (b) (c) (d) (e ) fig. 10. fe-sem of fgms sample with 5 layers: a) first layer, b) second layer, c) third layer, d) fourth layer and e) fifth layer. fadhi chyad al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 99107 (2018) 105 (a) (b) (c) (d) ( e) (f) (g) fig. 11. fe-sem of fgms sample with 7 layers: a) first layer, b) second layer, c) third layer, d) fourth layer and e) fifth layer, f) sixth layer and g) seventh layer. 4. conclusions functionally graded bam/lim specimens have been fabricated at three different set of layer (3, 5 and 7) by powder metallurgy. characterization of fabricated fgms was carried out by fesem which revealed gradation in microstructure from plate like structure (hard ferrite) to spherical structure (soft ferrite). the result of density indicate the high homogeneity and good blending between the layers of fgm led to increasing of density. the vickers hardness showed higher value at fgm7 layer 7. 5. references [1] feng shi, "ceramic materials progress in modern ceramics", in tech, pp.65-82, 2012. [2] sindhu s.," preparation and characterization of spinel ferritetheir incorporation in rubber fadhi chyad al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 99107 (2018) 106 matrix and evaluation of properties", department of physics cochin university of science and technology cochin, india, phd thesis, 2001. [3] m. tahani , m.a. torabizadeh and a. fereidoon,"nonlinear analysis of functionally graded materials" ,jamme, vol. 18 , pp.315318 ,2006. [4] l. jaworska , m. rozmus , b. królicka , a. twardowska ," functionally graded cermets", journal of achievements in materials and manufacturing engineering, vol.17,pp.73-76, 2006. [5] rasheedat m. mahamood, esther t. akinlabi member, iaeng, mukul shukla and sisa pityana," functionally graded material: an overview", proceedings of the world congress on engineering, vol. iii, 2012. [6] jaesang yu, cheol-min yan and yong chae jung," micromechanics modeling of functionally graded materials containing multiple heterogeneities" ,composite research, vol.26, pp.392-397, 2013. [7] mahmoud samir el-wazery and ahmed reffat ei-desouky," fabrication and characteristics of 8ysz/ni functionally graded materials by applying spark plasma sintering procedure", int. j. appl. sci. eng., vol. 12, pp.313-321, 2014 [8] f. attiay, a. raheem, s. ali," studying dielectric and magnetic properties of nano ferrite functionally graded materials" energy procida, accepted paper, 2017. [9] tatyana koutzarova , svetoslav kolev, kornely grigorov , chavdar ghelev, andrzej zaleski , robert e. vandenberghe , marcel ausloos , catherine henrist , h, rudi cloots , and ivan nedkov," structural and magnetic properties of nanosized barium hexaferrite powders obtained by microemulsion technique", trans tech publications, switzerland, vol.159, pp.57-62, 2010. )2018( 99107 ، صفحة1د، العد14دجلة الخوارزمي الهندسية المجلم صابرين عبد 107 ناعم المتدرجة وظيفيا -لمواد الفرايت صلب ةوالمورفولوجي ةالخصائص الفيزيائي *** عبد صابرين **أكرم جبر *فاضل جياد قسم هندسة المواد/ الجامعة التكنولوجية*،**،*** fchyad_2009@yahoo.de:البريد االلكتروني* akram.jabut@gmail.com **البريد االلكتروني: sabreenali217@gmail.comالبريد االلكتروني: *** الخالصة من عينات المواد ةنماذج مختلف ةفي هذا العمل تصنيع ثالثوتم سيراميك بأستخدام تقنية تكنلوجيا المساحيق. -المواد المتدرجة وظيفيا بمكونات سيراميك يثيوم) . فرايت الل) والفرايت الناعم (طبقات. المكونات السيراميكية متمثلة بالفرايت الصلب ( فرايت الباريوم ٧طبقات و ٥طبقات , ٣المتدرجة وظيفيا الى الماسح االلكتروني. لقد تم قياس بعض الخصائص ساعتين وتم تشخيصها بتقنية درجة سيليزيه لمدة١١٠٠جميع العينات تم تلبيدها بدرجة حراره ثابته عند زداد بأزدياد . أوضحت النتائج ان الكثافة تةتتضمن الكثافه الظاهرية, المضخمه,المساميه,االنكماش والصالد ةلعينات المواد المتدرجة وظيفيا المصنع ةالفيزيائي المواد داخل تركيب المواد المتدرجة وظيفيا. أوضحت صالدة فيكرز اعلى القيم عند يم حدوث تدرج بومن اهم العوامل لتق دد الطبقات. االنكماش الخطي يعدع من شكل صفائحي في الفرايت الصلب الى شكل كروي في الفرايت ةداخل المنظوم امجهري اوأخيرا أظهرت صور الماسح االلكتروني تدرج , fgm7عينة الناعم. شيماء وزينة al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 7, no.4, pp 88 – 96 (2011) the linear and nonlinear electro-mechanical fin actuator shaimaa a. mahdi zeina a. abdul redha department of energy engineering /college of engineering /university of baghdad email: s .alaasadi@yahoo.com (received 17 january 2011; accepted 17august 2011) abstract electromechanical actuators are used in a wide variety of aerospace applications such as missiles, aircrafts and spyfly etc. in this work a linear and nonlinear fin actuator mathematical model has been developed and its response is investigated by developing an algorithm for the system using matlab. the algorithm used to the linear model is the state space algorithm while the algorithm used to the nonlinear model is the discrete algorithm. the huge moment constant is varied from (-3000 to 3000) and the damping ratio is varied from (0.4 to 0.8). the comparison between linear and nonlinear fin actuator response results shows that for linear model, the maximum overshoot is about 10%, rising time is 0.23 sec. and steady state occur at 0.51 sec., while for nonlinear model the maximum overshoot is about 5%, rising time is 0.26 sec. and steady state occurs at 2 sec.; i.e., the nonlinear fin actuator system gives faster and more accurate response than does the linear fin actuator system. keywords: electro-mechanical actuator, fin, nonlinear actuators, response. 1. introduction the use of electromechanical actuation becomes increasingly popular in the aerospace industry as more importance is placed on maintainability. electromechanical actuators (emas) are being used in the actuation of flight critical control surfaces and in thrust vector control [milan r. ristanovic, dragan v. lazic and ivica indin 2008]. systems whose actuation mechanisms display both direct, i.e., mechanical work to electrical energy conversion, and converse effects between electrical charge and mechanical work employ electromechanical effects [anusha anisette 2007]. electro-mechanical servo systems have been steadily used in fin position servo systems of guided missiles, because of their momentary overdrive capability, low quiescent power/ low maintenance characteristics and long-term storability. during a flight, fin position servo systems have many uncertainties due to disturbances, parameter variations, and electrical noises and so on. furthermore fin position servo systems are subjected to aerodynamic load disturbances, such as the deflection angle of the control fin, the angle of attack and mach number [chung-hee yoo, young-cheol lee and sangyeal lee 2005]. in control system design, although linear control theory has wide range of applicability, very often some “nonlinearities” very often must be taken into account. although in the last few years the stability analysis of a single – input single – output (siso) system with saturating actuator was studied using a circle or popover , s criteria to analyze the stability of saturating system via pi control. since these criteria can only apply (siso) to stable plants, a complicated rearrangement of these systems is needed when applied to unstable plants. we should point out that such a technique of analysis is not easily extended to a multivariable case. mailto:.alaasadi@yahoo.com shaimaa a. mahdi al-khwarizmi engineering journal, vol. 7, no.4 , pp 88 96 (2011) 89 the objective of this paper is to formulate and solve the problem using the state – space model and discrete algorithm. after the fin’s position is assumed its velocity and acceleration is found by integrating the position equation to show the velocity and acceleration transient response. finally a design algorithm is proposed and a comparison is done between the linear and nonlinear fin actuation results. 2. fin actuator models two types of fin actuator models are discussed in this work : a linear second – order model and a nonlinear second – order model. 2.1. the linear model a simple model that could describe an actuator, s dynamics is a linear second – order system with demoing zeta (ζ) and natural frequency omega (ωn). the transfer function of a second – order system is given below, where (δ) is the output and (δc) is the input. figure (1) shows one of many possible methods of implementing the transfer function as a block diagram. g(s) = ( δ / δc ) =( ωn 2 / s2+2 ζ ωn s+ ωn 2) …(1) the differential equation describing system dynamics is [milan r. ristanovic, dragan v. lazic and ivica indin 2008, scott j. moody1989]: ̈ = ωn 2 ( δc – δ – ̇ ) … (2) the system state equations are : x = ax + b f(t) …(3) 1 2 =̇ 0 1− −2ζ 1 2 + 0 …(4) = [1 0] 1 2 …(5) where δ ( x1 ) is the fin position , ̇ ( x2 ) is the fin velocity , and ̈ ( ̇2 ) is the fin acceleration. the system response with time in linear model show in fig .2, fig.3 and fig.4 . fig. 1. second-order linear block diagram . shaimaa a. mahdi al-khwarizmi engineering journal, vol. 7, no.4 , pp 88 96 (2011) 90 fig. 2. linear position unit step response. fig. 3. linear velocity unit step response. fig. 4. linear acceleration unit step response. analytical solution since there is a difference between the solutions to the differential equations for actual and simulated systems, an analytical solution will be developed for comparison. the input (δc) will be a unit step [scott j. moody1989]: δc = 1 … (6) after laplace transfer: δc = 1/ …(7) from the transfer function: δ (s) = g (s) . δc (s) = ( ωn 2 / s ( s2+2 ζ ωn s+ ωn 2) ) …(8) δ (t) = l-1 [ δ (s) ] …(9) from a table of laplace transform, find the solution to δ (t): δ (t) = [ ( 1/ ωn 2) – (1/ ωn 2√(1− ζ 2)) eζ ωnt sin (ωn √(1 − ζ 2) + tan-1 (√(1 − ζ 2) / ζ ) ) ] ωn 2 …(10) where tan-1 (√(1− ζ 2) / ζ) = cos-1ζ δ (t) = [ 1 – (1/ √(1− ζ 2)) eζ ωnt sin (ωn √(1 − ζ 2) t+ cos-1ζ )] …(11) for a solution to the first integral, ̇ ( t ) : ̇ ( t ) = l-1 [ s δ (s) δ ( 0+) ] …(12) assume δ ( 0+) = 0 s δ (s) = ( ωn 2 /( s2+2 ζ ωn s+ ωn 2) ) …(13) from the laplace transform table: ̇ ( t ) = ωn 2[( 1/ ωn √(1− ζ 2)) eζ ωnt sin (ωn √(1 − ζ 2) t] …(14) ̇ ( t ) = [ωn eζ ωnt sin (ωn √(1− ζ 2) t] / √(1 − ζ 2) …(15) for example using an ωn of 144 rad/sec, and a ζ of 0.6, we get: δ (t) = 1 1.25 e-86.4t sin( 115.2t + 0.927 ) rad …(16) ̇ (t) = 180 e-86.4t sin( 115.2t ) rad/sec …(17) the system response with time in linear model with different values of zeta to find the beast one of stability to position show in fig .5 , velocity show in fig.6 and acceleration slow in fig.7 shaimaa a. mahdi al-khwarizmi engineering journal, vol. 7, no.4 , pp 88 96 (2011) 91 fig. 5. linear position unit step response . fig. 6. linear velocity unit step response . fig. 7. linear acceleration unit step response . 2.2. the nonlinear model a second type of model is one that contains physical limitations, which were added to the linear second-order model to yield a second-order nonlinear model. the second-order linear model was modified to include characteristics typical of an actuator motor. this resultant nonlinear model more closely emulates the real thing. these characteristics are inherent limitations of the physical system and are nonlinear. they include; position limits ( fin stops ), velocity limits ( slew rate limits ), acceleration limits ( tinite torque ), a dead band in the rate feedback , and aerodynamic hinge moments. fig.(8) shows a block diagram of second-order nonlinear model as it can be seen from the block diagram, there is no trivial analytical solution for the differential equation [scott j. moody1989]: ̈ = ωn 2 ( δc – δlim ratefb − ̇ ) hm … (18) shaimaa a. mahdi al-khwarizmi engineering journal, vol. 7, no.4 , pp 88 96 (2011) 92 fig. 8. second order non-linear block diagram . 2.3. the nonlinearities in the control system nonlinearities in control systems may appear due to one or more combination of the following [choudhury 2008]: a. the process may be nonlinear in nature. b. the control system may have a nonlinear characteristic. c. the control system may develop nonlinear faults (the work in this paper focuses on this type of nonlinearities by studying each fault and its effect on the servo system). d. a nonlinear disturbance may enter the system the main nonlinearities discussed in this paper are dead zone and saturation. 3. simulation results the response is for unit-step input because it is the type of input used in the control systems, and the simulations are carried out using matlab. fig. 9. non-linear position unit step response. shaimaa a. mahdi al-khwarizmi engineering journal, vol. 7, no.4 , pp 88 96 (2011) 93 fig. 10. non-linear velocity unit step response the position response with time in nonlinear model with different value of km show in fig .12 fig. 11. non-linear acceleration unit step response. fig. 12. non-linear position unit step response with different km. shaimaa a. mahdi al-khwarizmi engineering journal, vol. 7, no.4 , pp 88 96 (2011) 94 4. results and discussion the results of the simulation as follow fig.(2) shows the position unit–step response with time for linear model, the maximum overshoot is about 10% , rising time is 0.23 sec. and steady state occur at 0.51 sec. fig.(3) shows the velocity unit–step response with time for linear model, the max value of velocity is 70 rad/sec. and the steady state occur at 0.51 sec. fig.(4) shows the acceleration unit–step response with time for linear model, the max value of acceleration is 3.2 *10 4 rad/sec2. and the steady state occur at 0.51 sec. fig.(5) shows position unit–step response with time for linear model when ζ is between( 0.4 0.8), the maximum overshoot is between (30% 2%), while rising time between( 0.15 0.3) sec. and the steady state occur between (0.8 0.4) sec. i.e. if we decreased ζ, the overshoot increased and rise time is faster. fig.(6) shows the velocity unit–step response with time for linear model model when ζ is between( 0.4 0.8), the max value of velocity is between ( 90 – 60) rad/sec. and the steady state occur between( 0.8 – 0.4) sec. fig.(7) shows the acceleration unit–step response with time for linear modelwhen ζ is between( 0.40.8), the max value of acceleration is between ( 3.3 *10 4 3.1 *10 4) rad/sec2. and the steady state occur between( 0.8 – 0.4) sec. fig.(9) shows the position unit–step response with time for nonlinear model ,the maximum overshoot is about 5% , rising time is 0.26 sec. and steady state occur at 2 sec. fig.(10) shows the velocity unit–step response with time for nonlinear model, the max value of velocity is 27 rad/sec. and the steady state occur at 2 sec. fig.(11) shows the acceleration unit–step response with time for nonlinear model, the max value of acceleration is 104 rad/sec2. and the steady state occur at 2.2 sec. fig.(12) shows the nonlinear position unitstep response when various hinge moment constants were added between (3000 to 3000 ), the overshoot increased and the rise time is faster. the hinge moment hm is a function of the fin deflection and a hinge moment constant km. the results of the simulation show that the decreasing in maximum overshoot and the increasing in rising and steady state times for the nonlinear model because of nonlinearities effectiveness. however the nonlinear second order system gives faster and more accurate response especially in the presence of system parameter variations and external disturbances than did the linear system. 5. conclusions for linear model the transient response depended on the value of ζ, so if we decrease ζ, the overshoot increased and rise time is faster, while for nonlinear model the rise time is lengthened but the overshoot was less. in another hand when various hinge moment constants were added we found that the overshoot increased and the rise time was faster . so, the nonlinear second order system closely modeled the actuator’s dynamics and physical characteristics than did the linear system and gave faster and more accurate response especially in the presence of system parameter variations and external disturbances. notation t time sec s laplace transform km constant hm hinge moment m. n greek letters ξ damping ratio ∆ time change (t2-t1) ωn natural frequency rad /sec δc unit step function (input) δ fin position (output) rad δ' fin velocity rad /sec δ'' fin acceleration rad /sec shaimaa a. mahdi al-khwarizmi engineering journal, vol. 7, no.4 , pp 1 12 (2011) 95 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[7] francis h. raven (1982), " automatic control engineering", mcgraw-hill inc [8] katsuhiko ogata (1997), "modern control engineering", prentice hill international, inc. [9] katuhisa furuta (1988), "state variable methods in automatic control", printed and bound in great britain by biddles of guildford. [10] m.a.a.s. choudhury et al., (2008)," diagnosis of process nonlinearities and valve stiction, springer verlag", berlin, heidelberg [11] menon r. k. and iragavarapu v. r. (1998)," adaptive techniques for multipile actuator blending", optimal synthesis inc., boston. [12] milan r. ristanovic, dragan v. lazic and ivica indin (2008), "nonlinear pid controller modification of the electromechanical actuator system for aero fin control with a pwm controlled d.c. motor", automatic control and robotics vol. 7, no.1, 2008 pp.131-139. [13] murali mohan gade, k. k. mangrulkar, a.b. mote,(2008)," design of a selfdither controller for an electropneumatic fin actuator of a missile", proceedings of the international conference on aerospace science and technology, bangalore, india. [14] scott j. moody, (1989), " missile actuator simulation and investigation into accuracy of runge-kutta numerical integration". guidance and control directorate research, development, and engineering center, usa. )2011(88 96 ، صفحة4، العدد7مجلة الخوارزمي الھندسیة المجلد شیماء عالء الدین 96 والالخطيمشغل الزعنفة الكھرومیكانیكي الخطي زینھ علي عبد الرضا شیماء عالء الدین مھدي جامعة بغداد /كلیة الھندسة/قسم ھندسة الطاقة alaasadi@yahoo.coms.: البرید االلكتروني الخالصة في ھذا البحث تم . غیرھاحشرات التجسس وتستعمل المشغالت الكھرومیكانیكیة في أنواع مختلفة من التطبیقات الفضائیة مثل الصواریخ والطائرات و بناء نموذج ریاضي لمشغل الزعنفة الخطي والالخطي وقمنا بالتحقیق حول استجابتھ وذلك ببناء خوارزمیة للمنظومة وتطبیقھا برمجیا بینما الخوارزمیة المستخدمة لألنظمة الالخطیة ھي state spaceلالنظمة الخطیة ھي خوارزمیة الخوارزمیة المستخدمة . matlabدامباستخ ). ٠.٨إلى ٠.٤(نسبة التخمید ما بین وتغیر قیم ) ٣٠٠٠الى ٣٠٠٠-(وقد تم حساب قیم متغیرة لثابت العزم المضخم ما بین , الخوارزمیة المنفصلة ثانیة ویحدث ٠.٢٣ rising time و % ١٠ maximum overshoot وجد ان لمشغل الزعنفة الخطي والالخطي نة بین نتائج االستجابة ن المقارم یة ثان ٠.٢٦ rising timeو % ٥ maximum overshoot ثانیة لمشغل الزعنفة الخطي بینما لمشغل الزعنفة الالاخطي یكون ٠.٥١االستقرار عند .ثانیة ، أي انھ مشغل الزعنفة الالخطي یعطي استجابة اسرع وادق من مشغل الزعنفة الخطي ٢ویحدث االستقرار عند mailto:.alaasadi@yahoo.com (microsoft word \307\316\341\307\325 \346\345\310\311156-163) al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 14, no. 1, march, (2018) p.p. 156163 energy consumption analyzing in single hop transmission and multi-hop transmission for using wireless sensor networks ekhlas k. hamza* heba h. alhayani** *,**department of control and systems engineering / university of technology/ baghdad * email: ekhlas_kadhum@yahoo.com ** email: heba_alhayani@yahoo.com (received 11 april 2017; accepted 31 october 2017) https://doi.org/10.22153/kej.2018.10.009 abstract wireless sensor networks (wsns) are emerging in various application like military, area monitoring, health monitoring, industry monitoring and many more. the challenges of the successful wsn application are the energy consumption problem. since the small, portable batteries integrated into the sensor chips cannot be re-charged easily from an economical point of view. this work focusses on prolonging the network lifetime of wsns by reducing and balancing energy consumption during routing process from hop number point of view. in this paper, performance simulation was done between two types of protocols leach that uses single hop path and modleach that uses multi hop path by using intel care i3 cpu (2.13ghz) laptop with matlab (r2014a). the simulation results showed how the multi-hop protocol was more energy efficient than single hop protocol. keywords: energy-efficient, leach, modleach, networklifetime, wireless sensor network 1. introduction the improvements in mems (micro electromechanical systems) as well as in wireless communiqué have boost the extending of billions of small and low cost wireless strategies as well as various type of wireless systems which connect these devices with or deprived of any present arrangement[1] . wireless device networks (wsns) are dividing data acquisition system consisting of plentiful wireless sensor nodes. the fast arrangement, selfgroup and fault tolerance characteristics of wsns make them a very promising sensing technique for environmental, military and health applications. a wsns consists of hundreds and thousands off sensor nodes (sns). these sns have ability to monitor phenomenon's in the environment such as temperature, sound, pressure and communicate this information wirelessly with each other or directly to the base station (bs) [2].sns consists of sensors, processor, memory, communication system, mobilizer, position finding system, and power units ,see fig 1 [3]. one of the challenges of the successful wsns application is the energy consumption problem. [4] sns have incomplete battery lifetime. frequently their battery cannot be exchanged and re-energized due to area of their deployment, so, the network life span be contingent upon the initial battery capacity of sns. a careful management of the resources should be used here to increase lifespan of wsns. and the excellence of routing proprieties also be contingent upon the amount of data (real facts indication) positively expected by bs from sns organized in the network area. number of routing protocols has been proposed for wsns [5, 6] , figure 2 show the routing protocol classification. proprieties are more categorized as practical, sensitive and mix, conditional on the kind of ekhlas k. hamza al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 156163 (2018) 157 message routes processed within the network for data communication from the source to bs . in active routing proprieties all the pathways are considered before the bs makes an beginning to connect with the sns in the system, whereas in reactive routing protocols the path values are calculated only when required. the path values are calculated and best path is choice for data transmission when a bs wants to communicate with sns. hybrid routing protocols is a gathering of both proactive and reactive protocols, depending on the type of communication the path calculated from the bs to the source[7] fig. 1. components of wsns node[3]. fig. 2. general classification of routing protocols in wsns[6, 8]. data gathering technique, also known as data fusion, is to optimize transmit data and obtain energy efficiency. data collection is defined as the collection of information from several sns in a systematic manner and sent to the bs for processing. since sns could make important dismissed information, that could be similar data aggregated as well for achieving the reducing of data in the small groups of significant material. while, data combination is the combination of data that minimized into small groups of meaningful information from various sources according to a certain aggregation function [9, 10] single hop transmission using when small scale network and when sns close to bs. multi hop transmission using when large scale network and when sns far away from bs . when the transmitter distance is proportional to d4 the long distance is divided into sub ekhlas k. hamza al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 156163 (2018) 158 distances this needs more energy efficient , the power attenuation is proportional to the d2 [1] . this research is planned as follows: section 2 consists of the brief description about the low energy adaptive clustering hierarchy (leach) and modify low energy adaptive clustering hierarchy (mod-leach) protocols. section 3 describes system model and assumptions. section 4 describes the implementation of the experiment section 5 simulation results along with comparisons are discussed and lastly, section 6 concludes the paper. 2. low energy adaptive 2.1. clustering hierarchy (leach) the first hierarchical routing protocol in the wsns is leach (low-energy adaptive clustering hierarchy) protocol[11, 12] , single hops path selection[13] and proactive routing protocol[14] . leach protocol is organize the sns into cluster, there is elected sns called cluster head (ch) and the rest nodes a called cluster member (cm) (leach shown in figure 3 ). leach down into rounds, each round has two phase :the setup phase and the steady state phase . 2.1.1 setup phase in this phase, clusters are formed and a ch is chosen for each cluster. every sn (n) chooses number randomly between 0 and 1. if this unsystematic quantity is less than inception value t(n), the sn will become a ch for the present round[15]. t(n) is defined as follows: t(n) = � ����� �� �� � if n ∈ g 0 otherwise …(1) [15] where p is the percent. ch to all of the nodes r is the current round g is the set of nodes that was elected in the past 1/p rounds of election. mod () is the modulus function. when r = 0, the chance of each sn can become the ch is p. in the first r rounds if and sn becomes the ch, it can be not reelected in the future time (1/p – r) round which boost the option of other sns to develop a ch. all sns have the possibility of p to be a ch once again over and over again when 1/p rounds. a sn is designated as a ch at random. the ch node broadcasts messages to the environment, and other sns select a cluster to join in, subject to the intensity of the broadcasted messages they received, and then inform the corresponding chs. a ch communicates with a bs directly and the cms only communicate with the ch in their own cluster. while clusters are forming, each ch creates a tdma schedule giving to the number of sns in the cluster. each sn transfers their detected data to its ch through its distributed transmission time in the tdma [11-13]. 2.1.2 steady-state phase in the phase, all the cms start detecting data and send it to their chs giving to the tdma schedule. the ch compresses the receiving data and sending it to the bs. communication will be via direct-sequence spread spectrum; each cluster uses a unique spreading code to reduce inter-cluster interference. after an estimated period of time the network again goes into the setup phase and enters another round of selecting chs[11-13]. fig. 3. leach protocol [16] ekhlas k. hamza al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 156163 (2018) 159 2.2. modify low energy adaptive clustering hierarchy (mod-leach) mod-leach is one of hierarchical routing protocols in the wsns introduce by [14] , work of this protocol based on leach. it is multi hop protocol if the distance between chs and bs far multi hop path communication is adopted among chs [8] and proactive routing protocol [14]. this protocol modulating leach through put in “efficient ch replacements scheme”. for the next round, it has the threshold in the ch formation. the existing cluster will also remain ch for the next round when it has no enough energy to consume during its time and has more energy than essential edge .this matter describes how energy unused in routing packets for cluster formation and new ch can be saved accordingly. so, if ch has low energy than required for threshold; then leach algorithm will be exchange in cluster formation for limiting energy usage, according transmission nature two different levels can be used of power in order to amplify signals .three methods of communication in one cluster based system. 1)intra cluster transmission deals cms sense data and explosion recognized information to ch , 2) inter cluster communication can be named for the transmission/ reception between two chs , 3) ch to bs transmission is the transmission while a ch transmitting it’s data straight to bs[14]. mod-leach is more enhanced by using the idea of soft and hard threshold as presented by teen[14]. 3. system model and assumptions 3.1. assumptions the following expectations are made for the new scheme: • all sn are homogenous and stationary after deployment • the sink stationary and has the information about the location of each node. • each sn makes one data package per time unit to be communicated into sinks. we denote to each time unit as a round for simplicity. • sns are dispersed in a 2-dimensional space and cannot be recharged after deployment. • each sn is assigned a unique identifier (id). • each sn has the same initial power. • energy of transmission depends on the distances (source to destination) and data sizes. • radio’s channel can be considered as a symmetric i.e. to communicate a message from node m to node n the energy should be required and verse versa if a message from node n to node m is transmitted for a given snr. • the sn has no cooperation , moreover; it doesn’t attempt to contact the channel instantaneously and we study a lined wireless network designed for this examination. 3.2 radio energy model for approximation the energy depletion for sns and the system lifetime , we usage the principal instruction energy model (shown in fig. 4). this model introduces (presents) the energy consumed for sending and receiving l-bit communication above a distance d then transferring interested in a wireless account transmission and multi pathway transmission simulations. the communication energy in wireless typical can be considered as a relational to space d2, while for multi pathway spread classic, the energy is relational to space d4 according to unlike pathways that transfers the communicated indication to extent the receiver itself.[17]. fig. 4. first order energy model[17] ekhlas k. hamza al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 156163 (2018) 160 energy sends information of l bit package above a space d from a node to a ch otherwise a bs which is designed giving to under stated equation (2). etx = e elec (l)+ ɛamp(l,d) ...(2) where eelec energy consumed to transmit or receive the signals electronic circuit ɛamp energy consumed to transfer at a longer distance by the amplifier l no. of bits in a packet d distance between transmitter and receiver obtaining the crossover distance do that describes the spread evolution from through pathway to multipath typical: do= � ɛ�� ɛ�� ...(3) where ɛfs energy consumed to communicate at a smaller distance by the amplifier ɛamp energy spent to communicate at a longer distance by the amplifier the energy disbursed for wireless spread (where d < do) etx-fs is defined by: etx-fs= e elec.l + ɛfs . l.d2 ...(4) where eelec energy depleted in electronic path to communicate or accept the indication ɛfs energy consumed by the amplifier to communicate at a shorter distance l no. of bits in a packet d distance between transmitter and receiver the energy spent for multi-path spread (where d ≥ do) etx-mp is given by: etx-mp(l,d) = eelec . l + ɛmp . l.d4 ….(5) where e elec energy spent in electronic circuit to transmit or receive the signal ɛamp energy consumed by the amplifier to transmit at a longer distance l no. of bits in a packet d distance between transmitter and receiver the energy expended to receive l-bit message is defined as [11]: erx(l)=eelec.l ...(6) where eelec energy spent in electronic path to communicate or accept the indication l no. of bits in a packet 4. simulation to evaluate the performance of single hop and multi hop in wsns, we have performed in matlab (r2014a) when run for 5000 rounds with randomly deployment nodes. simulation parameters shown in table 1. single hop in our work can be obtained by implementation the leach and the modleach protocol present in implemented to obtain the multi hop in wsn, both leach and modleach are proactive (periodical transmissions). our goals in conducting the simulation are as compare the performance of the single hop protocol and multi hop protocol in wsns on the foundation of energy intemperance and the lifetime of the system. table 1, simulation parameter parameter value network size 100m×100m base station position 50 m × 75m number of nodes 100 percentage of ch 0.1 message size 2000 bit communication and reception energy 50 nj/bit energy increase for wierless 10 pj/bit/m2 energy amplification for multi path 0.0013 pj/bit/m2 initial energy for nodes 0.5j data aggregation energy 5nj/bit/message experiments in this work use two metrics to analyze and compare the performance of the protocols. they are: normal energy degenerate: this metric indications the average intemperance of energy per sns over time in the network. three features are measured to be accountable for intense the energy throughout facts routing which are: data send, data receive and data combined. network lifetime: is the time from the early of the test (turning all sensors on) until the instant when the first one expired. we use term fnd (first node dead) , hnd (half node dead ) and lnd(last node dead ) for indicate the lifetime of network. 5. results 5.1 average energy dissipated normal remaining energy of system per round as in shows fig. 5. each node has 0.5 j .the total ekhlas k. hamza al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 156163 (2018) 161 energy for 100 node is 50j (0.5j*100=50j). fig 5 clearly depicts that multi hop outperforms single hop in positions of energy depletion per round. multi hop yields minimum energy consumption than single hop because the space among sns is measured and wireless spread is frequently adopted as the minimization of inter-nodes space outcome in d2, as the connection cost factor in its place of d4 for multipath spread. this spread typical transformation well rises the energy productivity of the system. fig. 5.complete energy of the system against broadcast rounds for single hop and multi hop protocols. 5.2. total number of nodes dead: fig 6 & table 2 shows dead node number of network per round .the fnd is dead of the single hop protocol after 762 rounds and the lnd after 2650 rounds. the fnd of multi hop protocol is dead after 2020 rounds and lnd is lifeless after 3064 rounds. but totally the instrument nodes are expired when 2650 rounds for single hop procedure, wherever at the identical round practically 20% of nodes are still active in the multi hop .accordingly, the achieved instrument system by the multi-hop remains alive during more rounds. fig. 6. total dead node of the system against transmission rounds for single hop and multi hop protocols table, dead nodes for single hop and multi hop protocols fnd hnd lnd single hop 762 rounds 1510 rounds 2650 rounds multi hop 2020 rounds 2389 rounds 3064 rounds 6. conclusion steering process is of very significance in enhancing energy depletion in wsn. in this research, we present a compare the performance of the single hop protocoland multi hop protocol in wsn on the basis of energy dissipation and the lifetime of the network. outcomes of achieved models reveal that the multi hop protocol outclasses single hop procedure and allows the sns to improve communication energy and increasing the network lifetime. 7. references [1] j. wang, "hop-based energy aware routing scheme for wireless sensor networks",ph.d. thesis , kyung hee university seoul, korea, february, 2010. [2] m . hussain , r. h. chowdhury , m. hassan , m. a. hossain ,s. jahan and m. h. rahman , " performance analysis of various modulation schemes for achieving energy efficient communication over fading channel for wireless sensor network " iosr journal of electronics and communication ekhlas k. hamza al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 156163 (2018) 162 engineering (iosr-jece), vol. 11, issue 1, pp. 97-100 , 2016. [3] j. n. al-karaki and a.e. kamal, "routing techniques in wireless sensor networks: a survey". ieee wireless communications, vol. 11, no. 6 ,pp. 6-28, 2004. [4] j. wang, y. niu, j. cho and s. lee, " analysis of energy consumption in direct transmission and multi-hop [5] transmission for wireless sensor networks ", third international ieee conference on signal-image technologies and internetbased system , ieee , 2007. [6] m. aslam, m. b. rasheed, t. shah, a. rahim, z. a. khan, u. qasim, m. w. qasim, a. hassan, a. khan and n. javaid ," energy optimization and performance analysis of cluster based [7] routing protocols extended from leach for wsns", arxiv preprint arxiv:1309.4373, 2013. [8] p. k. singh," energy efficient clustered chain based power aware routing protocol for wireless sensor networks" , master thesis , national institute of technology rourkela , india , 2013 . [9] m. ali and s. k. ravula, " real-time support and energy efficiency in wireless sensor networks " , master thesis , halmstad university , halmstad, sweden, january, 2008. [10] s. rani and s.h. ahmed," multi-hop routing in wireless sensor networks: an overview, taxonomy, and research challenges"., springer ,2015. [11] jain, t. "wireless environmental monitoring system (wems) using data aggregation in a bidirectional hybrid protocol." in international conference on information systems, technology and management, springer, 2012. [12] p. kumar, a. chaturvedi, and m. kulkarni, "geographical location based hierarchical routing strategy for wireless sensor networks". in devices, circuits and systems (icdcs), 2012 international conference on,ieee, 2012. [13] w.b. heinzelman, a.p. chandrakasan, and h. balakrishnan, "an application specific protocol architecture for wireless microsensor networks", ieee transactions on wirelesscommunications,vol.1,no.4,pp.660 -670 , 2002 . [14] d. verma, r. jain, and a. shrivastava, "performance analysis of leach and leach-cc routing protocol in wireless sensor network" . iup journal of telecommunications ,vol.8 , no.3 pp.45, 2016. [15] l. an, a. li , l. pang and g. he, " analyss and comparison of routing protocol of wireless sensor network", international journal of online engineering,vol.12 ,no.10 , 2016. [16] d. mahmood, n. javaid, s. mahmood, s. qureshi, a. m. memon and t. zaman , " modleach: a variant of leach for wsns ", in broadband and wireless computing, communication and applications (bwcca), 2013 eighth international conference on.,ieee ,2013. [17] w.r., heinzelman, a. chandrakasan, and h. balakrishnan," energy-efficient communication protocol for wireless microsensor networks", in system sciences, 2000. proceedings of the 33rd annual hawaii international conference on,ieee , 2000. [18] a.k. singh, s. rajoriya, s. nikhil, and t. k. jain," design constraint in single-hop and multi-hop wireless sensor network using different network model architecture", in computing, communication & automation (iccca), 2015 international conference on. 2015. ieee. [19] i.f. akyildiz and m.c. vuran, "wireless sensor networks", john wiley & sons vol. 4. 2010. )2018( 156-163، صفحة 1دالعد ،14دجلة الخوارزمي الهندسية المجلم حمزة كاظم اخالص 163 تحليل استهالك الطاقة عند االنتقال بقفزة واحدة و بقفزات متعددة لشبكات االستشعار الالسلكية **الحيانيهبة حسين *اخالص كاظم حمزة ةقسم هندسة السيطرة والنظم/ الجامعة التكنولوجي **،* ekhlas_kadhum@yahoo.comالبريد األلكتروني: ** heba_alhayani@yahoo.comالبريد األلكتروني: * الخالصة من اهم .اقبة و الصحة و الصناعة و غيرهايمكن استخدام شبكات االستشعار الالسلكية في العديد من التطبيقات مثل التطبيقات العسكرية و المر س بسب الصعوبات التي تواجه شبكات االستشعار الالسلكية هي مشكلة استهالك الطاقة حيث من المستحيل اعادة شحن البطاريات المستخدمة في المتحس قة خالل عملية . في هذا العمل تم التركيز على اطالة عمر الشبكة عن طريق موازنه استهالك الطا صغر حجمها و صعوبة دمجها في رقائق المتحسس و المقارنة بين برتكولين يعمالن ضمن نفس البيئة البرتكول االول هو matlabالتوجيه . تم الحصول على النتائج من المحاكاة باستخدام برنامج leach الذي يمثل قفزة واحدة و البرتكول الثانيmod-leach قال عن طريق القفزات الذي يمثل متعددة القفزات . اظهرت نتائج المحاكاة ان االنت المتعددة افضل من القفزة الواحدة من ناحية استهالك الطاقة و اطالة عمر الشبكة . باسم حميد وزياد al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 48 -56 (2013) thermodynamic and kinetic study of the adsorption of pb (ii) from aqueous solution using bentonite and activated carbon bassim hameed graimed* ziad t. abd ali** *university of baghdad **department of environmental engineering/ university of baghdad *e-mail: bassim.hameed@yahoo.com **e-mail:z.teach2000@ yahoo.com (received 25 february 2013; accepted 24 april 2013) abstract the adsorption of pb(ii) ions onto bentonite and activated carbon was investigated. the effects of ph, initial adsorbent dosage, contact time and temperature were studied in batch experiments. the maximum adsorption capacities for bentonite and activated carbon were 0.0364 and 0.015 mg/mg, respectively. thermodynamic parameters such as gibbs free energy change, enthalpy change and entropy change have been calculated. these thermodynamic parameters indicated that the adsorption process was thermodynamically spontaneous under natural conditions and the adsorption was endothermic in nature. experimental data were also tested in terms of adsorption kinetics, the results showed that the adsorption processes followed well pseudo secondorder kinetics. keywords: bentonite, activated carbon, lead ions, adsorption, kinetic. 1. introduction according to the world health organization (who), the metals of most immediate concern are aluminum, chromium, manganese, iron, cobalt, nickel, copper, zinc, cadmium, mercury and lead. in particular, lead is one of the important toxic elements found in industrial effluents causing water pollution. lead is one of the industrial pollutants; possibly enters to the ecosystem through soil, air and water. inorganic lead causes disturbance in the central nervous system by changing the characteristics of the early organism [9,6]. according to who, the maximum permissible limit of lead in drinking water is 0.1 mg/l [16]. hence, the appropriate treatment of industrial wastewater which releases lead into the aquatic and terrestrial systems is very important. at present, a number of technologies can be used to remove heavy metals from the contaminated wastewater such as filtration, adsorption, chemical precipitation, ion exchange, membrane separation, and electroremediation methods [5,11]. however, most of these methods might not be efficient in removing heavy metal at very low concentrations, and could be relatively expensive. these methods are also not effective due to their secondary effluent impact on the recipient environment. hence, the simple, effective, low cost and eco-friendly techniques are required for the fine tuning of effluent wastewater treatment. the search for low cost, and easily available adsorbents has led to the investigation of materials of agricultural and biological origin, alongside those of industrial by-products as adsorbents for removal of heavy metals [8,13]. examples of such low cost adsorbents are clay [2], cotton [12], wool fiber [1], tea leaves [14] and other materials. the main aim of this study is the presence of heavy metals in water is a major concern due to their toxic effects since they cause severe health mailto:bassim.hameed@yahoo.com bassim hameed graimed al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 48-56 (2013) 49 problems to animals and human beings. many industrial processes produce aqueous effluents containing toxic metal contaminants. 2. experimental work and methods 2.1. preparation of adsorbents bentonite and activated carbon used were as the adsorbents in this study. bentonite was supplied by the state company of geological survey and mining (baghdad) as pieces of rocks, these rocks were destructed to granules of different sizes, using sieves to produce granules of sizes (0.5 0.6) mm, (de= 0.00054) m. the granules of bentonite were dried at (100) °c for (1) hour before used. granulated activated carbon (gac) was supplied by unicarbo, italians to the iraqi local markets. the granulated activated carbon was crushed, sieved into (0.50.6) mm, (de = 0.00054) m. the require sieve fraction was washed many times by distilled water to remove fines from the crushed gac and dried in an oven maintained at (100) °c for (2) hours, after which the gac was kept in a desiccators for experimental use. 2.2. preparation of simulated wastewater stock solutions (1000 mg/l) of lead ions were prepared by dissolving an appropriate weight of pure salt pb(n03)2 in the desired volume of de-ionized water. the stock solution was successively diluted with de-ionized water to obtain the desired test concentration (800 mg/l) of metal ions. concentration of lead ion was measured using atomic adsorption spectrophotometer (type: accusys 211 ,ukscientific ltd.). 2.3. adsorption experiments the batch experiments were performed by adding the desired amount (100 ml) of the dilute stock solution (800 mg/l) in 250 ml of volumetric flasks at the designated adsorbent dose, ph, and temperature. the solution was shaken using shaker at 200 rpm for a definite period (5, 10, 20, 40, 80, 120, 150) min. adsorbent dose, contact time, temperature and ph were optimized by continuous variation method (studying one, while keeping the other parameters constant). after equilibrium, the solution was allowed to settle for 20-30 min, filtered by filter paper (whatman 542, england) and analyzed for lead. the difference in the lead content before and after adsorption experiments represents the amount of lead adsorbed by the adsorbent. all experiments were performed at room temperature (20 °c), ph 4 by the addition of hno3 or naoh solution. the percent removal of metal ions can be calculated by using the following equation: %removal = [(c0-ce)/c0] × 100 …(1) where, c0 = initial concentration of the metal ion in mg/l, ce = metal ion concentration at equilibrium in mg/l. 2.4. contact time batch adsorption tests were carried out at different contact time intervals (5 150 min) at initial pb (ii) concentration of 800 mg/l. this was done by contacting 2 g of each adsorbent with 100 ml of pb (ii) solution at the ph 4. the residual pb (ii) concentration in each solution was then filtered using filter paper (type: whatman 542, england) and analyzed using atomic absorption spectrophotometer. 2.5. adsorbent dosage 100 ml of the metal ion solution of (800 mg/l) was added to various amount of the several adsorbents (0.2-3 g) in 250 ml volumetric flasks and agitated for 2hr on a shaker. the content of the glass bottles were filtered and analyzed by the same procedure mentioned above. 2.6. ph variation the ph value of the solution is an important controlling parameter in the adsorption process, and the initial ph value of the solution has more influence than the final ph, which influences both the adsorbent surface metal binding sites and the metal chemistry in water [15]. the effect of ph on the adsorption of pb (ii) using bentonite and activated carbon (each one separately) was carried out within the range that would not be influenced by the metal precipitated [10]. it was reported that the suitable ph range for the adsorption of pb(ii) was (2 8). this experiment was conducted at 20 °c to study the effect of initial solution ph on the adsorption of pb(ii) by contacting 2 g of the adsorbent (bentonite or activated carbon) with 100 ml of 800 mg/l pb(ii) solution in a volumetric flasks. the ph of each solution was bassim hameed graimed al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 48-56 (2013) 50 adjusted to the desired value with adding 0.1m hno3 and/or 0.1m naoh. the volumetric flasks containing the mixture were left in a shaker for 2h. solution was filtrated using filter paper and the pb(ii) concentration in the solution was analyzed by means of atomic absorption spectrophotometer. 2.7. agitation speed the effect of agitation of the sorbent/sorbate system for lead adsorption was monitored at (0, 100, 200, 300 and 400 rpm). 2.8. temperature variation the batch adsorption process was studied at different temperatures of 20, 30, 40, 50 and 60 °c in order to investigate the effect of temperature on the adsorption process using bentonite and activated carbon. this was done by contacting 2 g of adsorbents with 100 ml of 800 mg/l pb(ii) solution at ph 4 for 120 min with agitation speed of 200 rpm by using shaker incubator. the results were used to investigate the thermodynamics of the adsorption process. 3. kinetic equations the kinetics of lead adsorption on bentonite and activated carbon were analyzed using pseudo-first-order [4] and pseudo-second-order models [3], the pseudo-first order kinetic rate equation is: (dqt /dt)=k1(qe-qt) …(2) where k١ is the rate constant of pseudo first order adsorption (min-1 ), qe is the amount of lead sorbed at equilibrium (mg/mg) and qt the amount of lead sorbed at time t (mg/mg). integrating equation (2) for the boundary conditions t=0 to t= t and qt=0 to qt= qe and rearranging yields the linear time-dependent function. log(qe-qt) = logqe-(kt/2.303) …(3) the intercept of the straight-line plots of log (qe-qt) against t equal log qe , however, if the intercept does not equal qe, then the reaction is not likely to be first-order, irrespective of the magnitude of the correlation coefficient. the pseudosecondorder kinetic rate equation is: (dqt/dt)=k2(qe-qt)2 …(4) where k2 is the rate constant of pseudo second order adsorption (mg.mg-1.min-1).taking into account, the boundary conditions t=0 to t=t and qt=0 to qt=qt .the integrated form of equation (4) can be rearranged to obtain equation (5): (t/ qt)= (1/k2qe 2)+ (t/qe) …(5) the plot of (t/qt) and t of equation (5) gives a linear relationship, qe and k2 can be determined from the slope and intercept of the plot, respectively. 4. result and discussion 4.1. effect of contact time the effect of contact time on the adsorption of pb(ii) from the solution is shown in figure (1). fig. 1. time effect of the adsorption of pb(ii) onto bentonite and activated carbon at 20oc, ph 4, co=800 mg/l, rpm=200. it is observed that the removal of pb(ii) increased with increase in contact time. the adsorption of pb(ii) by the bentonite was rapid for the first 20 min as a result of available binding sites on the bentonite, while the adsorption by activated carbon was less rapid than bentonite. the adsorption reached equilibrium within 120 min as the binding sites on the bentonite and activated carbon were used up. the period of 120 min was therefore used for the adsorption of pb(ii) by bentonite and activated carbon. the initial fast removal occurs due to surface adsorption on the adsorbent. the subsequent slow phase occurs due to diffusion of the metal ions into the inner part of the adsorbent. bassim hameed graimed al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 48-56 (2013) 51 4.2. effect of adsorbent dosage the adsorption of lead ions was observed to increase as the amount of adsorbent is increased gradually from 0.2 to 3.0 g, (figure 2). fig. 2. effect of adsorbent dose (ph =4, co = 800mg/l, rpm=200, time=2 h). the maximum removal is obtained at the adsorbent dose of 2.0 g where a further increase in the quantity of the adsorbent up to 2 g has no more effect to the adsorption rate. therefore, 2.0 g of the adsorbent is sufficient to adsorb the maximum ions and that the percent removal by bentonite was more than that of activated carbon. also the removal efficiency is associated with the adsorbent dose increases which are due to the availability of more adsorbing sites at higher doses. 4.3. effect of ph on adsorption the ph of solution was examined at different ph values, covering a range of 2.0-8.0. in the case of pb(ii) the maximum adsorption was obtained at ph 4.0 for both adsorbents. removal of pb(ii) onto bentonite and activated carbon is ph dependent as shown in figure (3). fig. 3. effect of ph on the adsorption of pb(ii) by bentonite and activated carbon, at 20°c , co= 800 mg /l, rpm=200. at ph < 3.0, h+ ions compete with pb(ii) ions for the surface of the adsorbent which would hinder pb(ii) ions from reaching the binding sites of the sorbet caused by the repulsive forces. at ph > 5.5, the pb(ii) will precipitate due to hydroxide anions forming a lead hydroxide precipitate. for this reason the maximum ph value was selected to be 4.0. the highest efficiency was observed 91.1 % at ph of 4.0 for bentonite and 37.5 % for activated carbon. change in ph of the solution after adsorption was observed in this study for example, the ph value changes from 4 to 3 for bentonite dose of 1.0 g, to ph value of 2.65 for bentonite dose of 2.0 g and to ph values of 2.1 for adsorbent dose of 3.0 g. in all cases, ph of the solution decreases after equilibrium was reached. therefore the study indicated that a change in ph value is dependent on the amount of adsorbent dose. thus higher the adsorbent dose the larger the change in ph until the equilibrium is attained. the study further alluded that adsorption of the metal ions on the surface could result in the release of more h+ ions from the surface, indicating ion exchange mechanism as shown from the decrease of the ph from the initial ph value. 4.4. effect of agitation speed experimental results of the effect of agitation speed (0,100, 200, 300, and 400) are presented in figure (4). it is obvious that agitation is found to be appropriate for maximum adsorption of lead from minerals. the removal of pb (ii) is reaching 99.3% and 42.5% using bentonite and activated carbon respectively at 400 rpm, figures (4 and 5). fig. 4. percentage removal of lead with various agitation speeds for bentonite. bassim hameed graimed al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 48-56 (2013) 52 fig .5. percentage removal of lead with various agitation speeds for activated carbon. it can be seen that the removal percent increases with increasing agitation speed because increasing of agitation speed will decrease the boundary layer resistance, furthermore this experiment shows that the higher removal level reached by bentonite. 4.5. effect of temperature the extent of lead ion adsorption on the bentonite and activated carbon at various temperatures is shown in figures (6 and 7). fig. 6. effect of temperature (ph=4, adsorbent dose = 2 g, rpm=200, time = 2h). fig. 7. effect of temperature (ph = 4, adsorbent dose = 2 g, rpm=200, time = 2 h). as observed from the figures, temperature rises therein resulted in an increase in the removal a percentage of the metal. the enhancement of the adsorption capacity when temperature is increased could be due to increased mobility and diffusion of ionic species the adsorption experiment could be regarded as a heterogeneous and reversible process at equilibrium. the apparent equilibrium constant for the process is shown to be: kc = cad/ce ...(6) the gibbs free energy of the adsorption process [7] is: ag° = rt in kr ...(7) ag° is the standard gibbs free energy change for the adsorption process(j mol-1); r, the universal gas constant (8.314 j mol-1k-1) while t is the temperature (k). the effect of temperature on the adsorption of pb(ii) by bentonite and activated carbon is listed in table (1) and shown in figures (8 and 9). table 1, gibbs free energy values obtained from the adsorption of pb (ii) using bentonite and activated carbon at different temperatures. temperature (k) ag° (kj mor'k-1 ) bentonite activated carbon 293 -5.66 1.244 303 -6.93 1.245 313 -8.44 1.202 323 -10.45 1.198 333 -11.58 1.108 bassim hameed graimed al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 48-56 (2013) 53 fig. 8. the gibbs free energy plot for the adsorption of pb(ii) using activated carbon at ph 4 , co= 800 mg/l, rpm=200. fig. 9. the gibbs free energy plot for the adsorption of pb(ii) using activated carbon at ph 4 , co= 800 mg/l, rpm=200. the free energy change (ag°) obtained for the adsorption of pb(ii) at 293 k, initial concentration of 800 mg/l, and ph 4 is (-5.66 and 1.244)kj mol-1 for bentonite and activated carbon respectively. the negative value of ag° obtained for the adsorption of pb(ii) onto bentonite shows spontaneity of the adsorption process at that temperature, opposite for activated carbon. however, the result in table (1) shows that the free energy values for bentomte and activated carbon decreases with increasing temperature. this implies that the spontaneity of the adsorption process increases with increasing in temperature. consequently, the adsorption of the pb(ii) using bentonite and activated carbon as adsorbents is endothermic hence the process is better carried out at kindly high temperature. from thermodynamics, ∆g° = ∆h -t∆s …(8) or ∆g° = ∆s (t) + ∆h …(9) a plot of temperature against ag° gives a straight line with slope as0 and an intercept of ∆h. in (figures 7 and 8) the slopes are (0.1536 and 0.0035) kj/mol while the intercepts are (39.465 and 2.197) kj/mol for bentonite and activated carbon respectively. therefore, the values of the entropy are (0.1536 and 0.0035) kj/mol and enthalpy are (39.465 and 2.197) kj/mol for bentonite and activated carbon, respectively. the decrease in the value of the free energy with increase in temperature indicates that the adsorption process is endothermic and it is thereby favored with kindly increase in temperature. 4.6. kinetic study it is clear from figures (10, 11, 12 and 13) and table (2) that the reactions for bentonite and activated carbon are not likely to be firstorder because of the value of qe (experimental) does not equal to the value of qe(theoretical), irrespective of the magnitude of the correlation coefficient, while the values of qe (experimental) and qe(theoretical) are very close with higher value of correlation coefficient in case of second order, therefore the adsorption processes followed well pseudo secondorder kinetics for the two adsorbents. fig. 10. pseudofirst order for bentonite. fig. 11. pseudosecond order for bentonite. bassim hameed graimed al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 48-56 (2013) 54 fig. 12. pseudofirst order for activated carbon. fig. 13. pseudosecond order for activated carbon. table 2, constants of pseudofirst and second order. 5. conclusion the potential use of bentonite and activated carbon as an adsorbents for lead(ii) was studied. it was found that bentonite is more effective than activated carbon for removal high concentration of pb(ii) from aqueous solution, the maximum adsorption capacities for bentonite and activated carbon were 0.0364 and 0.015mg/mg, respectively. the percentage removal was strongly dependent on the adsorbent dosage, contact time, agitation speed and initial ph. the study of the thermodynamic parameters indicated that the adsorption process was thermodynamically spontaneous under natural conditions and the adsorption is endothermic in nature. the process kinetics was found to follow the pseudo-second order rate equation. 6. references [1] balkose, d.; balatacioglu, h. j. chem. technol. biotechnol. 1992, 54, 393. [2] farrah, h.; pickering, w.f. aus. j. chem. 1977, 30, 1417. [3] ho, y. s. (2006).review of second-order models for adsorption systems. j. hazardmater,, 136,681-689. [4] ho, y.s. (2004). citation review of lagergren kinetic rate equation on adsorption reactions. scientometrics, 59,171-177. [5] horsfall, j.m.; abia, a.a. water. res. 2003, 37, 4913 [6] johnson, p.m. mutat. res. 1998, 410, 123. [7] khan ar, tahir h, uddin f, hammed u (2005) adsorption of methylene blue from aqueous solution on the surface of wool fiber and cotton fiber, j. appl. sci. environ. manage. 9 (2): 29-35 [8] paulino, a.t.; simonato, j.i.; garcia, j.c.; nozaki, j. carbohydr. polym. 2006, 64, 98 [9] paulino, a.t.; tessari, j.a.; nogami, e.m.; lenzi, e.; nozaki, j. environ. contam.toxicol. 2005,75,42. [10] pavasant p, apiratikul r, sungkhum v, suthiparinyanont p, wattanachira s, marhaba tf(2006). biosorption of cu2+, cd2+,pb2+ and zn2+ using dried marine green macroalga caulerpa lentillifera. bioresour. technol. 97: 2321 – 2329 adsorbent qe(mg/mg) experimental pseudofirst – order pseudo – secondorder bentonite 0.0364 k1,(min)-1 0.073 qe, (mg/mg) 0.0177 r2 0.8619 k2, (mg.mg-1min-1) 7.2653 qe, (mg/mg) 0.037 r2 0.9992 activated carbon 0.015 k1,(min)-1 0.0347 qe, (mg/mg) 0.0031 r2 0.7659 k2, (mg.mg-1min-1) 67.768 qe, (mg/mg) 0.014 r2 0.9983 bassim hameed graimed al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 48-56 (2013) 55 [11] reddad, z.; gerente, c.; andeers, y.; pierrele, c. environ. sci. technol. 2002, 36, 2067. [12] robert, e.j.; rowland, s.p. environ. sci. technol. 1973, 7, 552. [13] tahir, s.s.; rauf, n. j. chem. thermodynamics 2003, 35, 2003 [14] tee, t.w.; khan, r.m. environ. technol. lett. 1988, 9, 1223. [15] waranusantigul, p.; pokethityook, p.; kruatrachue, m.; upatham, e.s. environ. pollut.2003,1,385. [16] who guideline values for drinking water quality, vol. 1, recommendations, world health organization: geneva; 1984; p. 81. )2013( 4856، صفحة 2، العدد9مجلة الخوارزمي الھندسیة المجلد باسم حمید جریمد 56 من محلول مائي ) ii(ة الحراریة والحركیة المتزاز الرصاص یالدینامیكالخواص دراسة الكاربون الفعالباستخدام البنتونایت و **زیاد طارق عبد علي *باسم حمید جریمد جامعة بغداد* جامعة بغداد / قسم الھندسة البیئیة ** bassim.hameed@yahoo.com : االلكتروني البرید* z.teach2000@ yahoo.com : االلكتروني البرید** الخالصة ، phتأثیر كل من الحامضیة دراسةكما تم . كمواد مازه الفعال و الكاربون البنتونایتباستخدام (ii)الرصاص امتزاز ایوناتتم التحري عن لكاربون الفعال ولبنتونایت و اامتزاز ل بلغت اعلى نسبة. درجة الحرارة باستخدام تجارب االمتزاز الكتليوفترة التماس، و، وكمیة المادة المازة ، في طاقة جبس الحرة الحراریة الحركیة لعملیة االمتزاز كالتغیر وكذلك تم دراسة الخواص. ملغم مادة مازة على التوالي/ ملغم ٠.٠١٥و ٠.٠٣٦٤ تلقائیة تحت االنتروبیة وقد تبین عند دراسة الخواص الحراریة الحركیة اعاله بان عملیة االمتزاز ھي عملیة حراریة حركیة و األنثالبیة والتغیر في وأخیرا تم دراسة الطاقة الحركیة لالمتزاز وبعد تحلیل النتائج تبین ان حركیة االمتزاز تتوافق مع الحركیة . الظروف االعتیادیة وإنھا ممتصة للحرارة . االمتزازیة من الدرجة الثانیة mailto:bassim.hameed@yahoo.com al-khwarizmi engineering!!! journal al-khwarizmi engineering journal, vol. 7, no. 2, pp 83 90 (2011) الضوضاء الناتجةشّدة دراسة تأثیر اضافة االیثانول الى الكازولین على بالشرارة یعمل أحادي االسطوانة من محرك عادل محمود صالح جامعة التكنولوجیةال /المعداتقسم ھندسة المكائن و del196150@yahoo.coma: البرید االلكتروني (received 10 january 2011; accepted 26 may 2011) الخالصة بالصوت غیر (، ویمكن تعریف الضوضاء ١٩٩٠ابتداءا من عام الضوضاء الناتجة عن المحركات واألنواع المختلفة من االنظمة كملوث عتبرت ویوجد في عدة دول .، وتنتج المحركات الكبیرة مستویات عالیة من الضوضاءھصحال علىه خطر ھاعالیة یمكن اعتبارالمستویات الوفي ،)مرغوب بھال من السیارات الضوضاء الناتجة دمغلقة في السفن والتطبیقات الثابتة، وتعالمحركات القوانین تحدد المستویات المقبولة من الضوضاء المسموح بھا في غرف .التقنیات القادرة على التحكم و السیطرة علیھالوجود أقل تأثیرا ذو اسطوانة واحدة یعمل باضاقة االیثانول الى الكازولین، وأخذت البیانات لسرع متعددة، بدون محرك احتراق داخلي على دراسة أجریت بحثفي ھذا ال المنبعث الصوت طبیعة نأستخدام عازل صوتي ومع استخدام عازل وعازلین، أظھرت النتائج ، وبدون ا%٢٠و ١٠اضافة ومع اضافة ایثانول بنسبة ثبتت أن اضافة الكحول ال تؤثر كثیرا على مقدار الصوت المنبعث من المحرك، كما أن الضوضاء تزید بزیادة عدد دورات المحرك، وأحادي القطب، كما أ .لیل الضوضاء بنسبة عالیةالدراسة أن استخدام عازل صوتي واحد یكفي لتق .الضوضاء في المحركات :المفتاحیة لكلماتا المقدمة.١ تستلمھ ،الصوت ھو االضطراب المنتقل خالل وسط فیزیاوي یط ــاالذن البشریة كموجة ضغطیة مضافة الى ضغط الھواءالمح دي ــــــوت التباین التزایــــغط الصـلذلك یمثل ض ،تمعـــبالمس sound)یطــوي لذلك المحــــغط الجــن الضـــع transmission class, 2005). إن سماع االنسان للصوت ال یعود فقط الى تمتعة بجھاز ناقل المادي اللوسط لالسمع ذو التركیب الخاص، وإنما كذلك فبدون وسط مادي ال یمكن للصوت الوصول الى ،للصوت إن والضوء، ة حالالسامع، فالصوت ال ینتقل بالفراغ كما في سماعنا للصوت من أي مصدر خارجي یعود بفضل وجود الھواء وجمیع الغازات والسوائل واالجسام الصلبة تصلح النتقال ،حولنا الصوت ولكن بسرع مختلفة وحسب الوسط الناقل لھ (adams, 2006). إن االذن البشریة تسمع االصوات التي یقع ترددھا ضمن ، لذا یتطلب توفر وسیط و مصدر)ھرتز ٢٠٠٠٠الى ٢٠(المدى ضغط یقاس الصوت بمستوىو، )االذن البشریة(مستقبل و :الصوت والذي یعرف بالمعادلة التالیة s.p.l= 20log p/po الضغط poحیث ، decibel (db)مقاسا بوحدات الدیسیبل وتي مسموع صویمثل أقل ضغط n/m2 2*10-5المرجعي ,al-ati]لعتبة السمع 2006]. الصوت غیر المرغوب فیھ ویسبب ب فتعرف الضوضاءأما االزعاج ویؤثر في حالة االنسان النفسیة وجھازة السمعي (guide to acoustics, 2006). یبین مستویات الضوضاء لغرض التصمیم ةالتالی التصنیفاتو :(hz 100-920)مقاسة عند التردد db 115 مؤلم db 100 مزعج جدا db 70 مشوش 60 لكالممدى ا db db 30 المستحب مستوى الصمت db 20 یسمع بالكاد :تقسم الضوضاء الى صلبة تنشأ عن اھتزاز االجسام ال( الضوضاء المیكانیكیة أ .)بتردد یصل الى مدیات مسموعة وسبب االھتزاز میكانیكي :، وتنقسم الى نوعینضوضاء الموائع ب یر في ضغط الھواء مقاسا الى غت(ضوضاء الدیناھوائیة .١ ).معدل ضغط الھواء او بسبب الجریان المضطرب تنتج ھذة الضوضاء نتیجة : رودینامیةدیاالضوضاء الھ.٢ مع الزمن في مائع ما فعالیة تعطي مجال ضغط متغیر .ستاتيقیاسا الى معدل الضغط األ :ویمكن تقسیم أنواع الضوضاء بشكل آخر  الضوضاء المستمرة(continuous noise)  الضوضاء المتقطعة(intermitted noise) this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ 90 ، صفحة2، العدد 7مجلة الخوارزمي الھندسیة المجلد عادل محمود صالح 83 )2011( 84 الصوت، ) كالھواء(تسبب الموجات الضغطیة في وسط مرن زات تسبب ویولد بواسطة اھتزاز أجزاء المحرك، ھذة االھتزا ذن أالى نبضات ضغط في الھواء، وھذة النبضات تنقل الطاقة االنسان، وكلما زادت الطاقة المنقولة، ارتفع الضجیج، ولحسن الحظ ان االذن البشریة لیست حساسة جدا، ولذلك فان المقیاس الكمي ھو مقیاس لوغارتمي بوحدات دیسیبل، فللمحادثة االعتیادیة یل، وتبدأ االذن باالحساس بااللم بدیس ٥٥صوت بحدود المستوى قوانین الیل، والعدید من بدیس ١١٥عند بلوغ الصوت مستوى ١١٠سمحت بضجیج لغایة وحددت الصوت لغرف المحركات .(guide to acoustics, 2006) دیسیبل إن حساسیة االذن البشریة مرتبطة بشكل كبیر بذبذبة لعالمیة الى ثالث فئاتالصوت، ولھذا السبب، تقسم المعاییر ا a ،b وc ،كل واحدة منھا مرتبطة بمجال محدد من الذبذبات ، حدد مستوى المقبول للضجیج اثناء قیادة ففي الوالیات المتحدة بة عند وھذا المعیار یجب العمل. (a)یل بدیس ٧٤العربة بحدود تصمیم سیارات في مساحات مثل مكان كاتم الصوت وانبوب .(reno, 2007). مالعاد تتولد الضوضاء بطرق عدة في محركات االحتراق الداخلي، حاقنات في لدخول والعادم، اغازات نبضات ضغطیة في مجرى ك ئدة، اضافة الى السالسل القاالشاحن الجبري، القوایش وو ،الوقود اذا لم یحتوي نظام العادم و لمحرك،ان مكونات االھتزاز الناتج م فان الضوضاء المتولدة ستكون ،جزاء مرنةأعلى كاتم صوت و .(berendt, 1976) مشكلة حقیقیة دراسة للضوضاء jones & brownأجرى الباحثان تحداث ـــباسالمنبعثة من منظومة عادم في محرك ثنائي االشواط اء العادم ـــحیث تم افتراض ضوض ائیةـــاحص تقنیة بــادي القطــحدر اــتراض ان المصــة بافـــــــــالمنبعث (jones& brown, 1983). اھتم بقیاس منسوب الضغط فقد stanianoاما الباحث الصوتي للمركبات قبل وبعد صیانة انظمة العادم فیھا داخل ورش ن القیاسات لمنسوب الضغط أووجد الباحث ،صیانة انظمة العادم (db 6-3)قدار الصوتي عند انبوب الخروج اوضحت تخفیض بم ن الضوضاء في محركات ذات ثمانیة أكما ،حسب نوع المحرك اسطوانات اكثر مما علیة لمحركات ذات أربعة اسطوانات (staniano, 1983). دراسة تأثیر محرك الدیزل على األذن البشریة ومدى التغیر ول ا في طبیعة الصوت والذي یسبب األزعاج وما یولده استنتج إن الزیادة في الضوضاء kantarelis & walkerالباحثان ناتجة عن زیادة سرعة المحرك، وإنھ یمكن تقلیل الضوضاء الف التصامیمــــــــــباخت 8db-5بة من ـــــــبنس (kantarelies &walker, 1988). ثیر الضوضاء المنبعثة من أت درستفقد wafaaاما الباحثة والضوضاء المنبعثة من مروحة تبرید ،محرك احتراق داخلي یھدف بحثھا و ،غازات العادم، وتحدید طبیعة المصدر الصوتي ازات ــومة غــوتیة لمنظــواص الصــة تأثیر الخــدراس الى وذج ـــمیم وبناء نمــالل تصـــــــــرك من خــادم لمحــالع .(wafaa m salih, 1999) ةـــمنظوملل التأثیرات األھتزازیة للكتل والقوى lighthillدرس الباحث أن اجھاد القص األضطرابي یمكن كمصادر ضوضاء، واستنتج ان یكون مصدرا للضوضاء، واشتق معادلة تجمع بین معادالت :األستمراریة والزخم في معادلة الباحث تمثل الحدود الثالثة على الطرف األیمن lighthill الصوتي، فالحد مصادر الصوت السائدة لالشعاع ، أما الحد (monopole)یمثل مصدرا أحادي القطب األول فیمثل مشتقة القوى الالثابتة ولھ خاصیة مصدر ثنائي الثاني ، أما الحد األخیر فلھ خواص مصدر رباعي (dipole)القطب .(lighthill, 1952) (quadrupole)القطب ,ahmed) ا ألنواع مصادر الصوتمخطط ١یوضح الشكل 2010) . .أنواع المصادر التي تولد الضوضاء -١-الشكل العملي الجانب.٢ وملحقاتھ المحرك.١.٢ حادي أمحرك احتراق داخلي في ھذا البحث استخدم رباعي االشواط یعمل بنسب انضغاط ،االسطوانة یعمل بالشرارة كما ھو موضح ،variable compression ratiosمختلفة ایطالي (ma230/a91/001)نوع المحرك ،٢بالشكل رقم یبرد بالماء، ومزود بدینامومیتر (prodit)الصنع انتاج شركة انتاج شركة (gr306/000/ 037a)ھایدرولیكي نوع (prodit). صورة للمحرك المستخدم في البحث مع ٢یبین الشكل .ملحقاتة .صورة جھاز المستخدم بالبحث -٢-كل الش this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ 90 ، صفحة2، العدد 7مجلة الخوارزمي الھندسیة المجلد عادل محمود صالح 83 )2011( 85 أجھزة القیاس .٢.٢ speed transducerمقیاس السرعة .١.٢.٢ لقیاس optical encodingتم استخدام المتحسس الضوئي عدد دورات المحرك حیث یأخذ االشارة من المحرك الى لوحة .السیطرة والحاسوب torque transducerمقیاس العزم .٢.٢.٢ strainاستخدم متحسس gauge لقیاس العزم إذ ینقل االشارة لألحمال المتغیرة بواسطة سلك الى لوحة السیطرة كما في الشكل وتمت معایرة الجھاز قبل التجارب للتأكد من سالمة عملھ .على الذراع األثقالباستخدام طریقة مقیــاس مســـــتوى ضــــغط الصــــــــــوت .٣.٢.٢ sound pressure level metering بواسطة المقیاس over all sound pressureتم قیاس precision sound level meter type 2209 مزود بالقطة microphone كما یوضح الشكل وتم معایرة (4615)من طراز )من طراز calibratorالجھاز بواسطة مقارن معیاري pistophone 4220). .المستخدم في القراءاتصورة للجھاز ٣یبین الشكل مقیاس مستوى ضغط الصوت المستخدم في البحث ٣-الشكل (overall sound pressure ). العازل الصوتي.٤.٢.٢ وایضا (mm 16)تم استخدام عازل صوتي من الفلیین سمكھ لبیان تأثیر العزل على شدة (6mm)عازل من الزجاج سمكة .المحرك الضوضاء المنبعثة من خطوات العمل وتسجیل القراءات.٣.٢ تضمن الجانب العملي اجراء تجارب لثالثة مراحل، تركزت االولى حول دراسة الضوضاء المنبعثة من المحرك عند سرع ، وبدون اضافة (rpm 1900-1200)متغیرة، تراوحت ما بین واجریت نفس التجارب . كحول وبأحمال مختلفة وبدون عازل عازل الفلیني، وسجلت قراءات شدة الضوضاء بوجود باستخدام ال العازل الفلیني، وبعدھا باستخدام عازلي الزجاج والفلیین مع وجود .سم ١٠فراغ بینھما بسمك من كحول % ١٠اما المجموعة الثانیة فقد تضمنت اضافة االیثانول الى الوقود المستخدم، واعادة التجارب بنفس نسق .المرحلة االولى من االیثانول الى % ٢٠تضمنت المجموعة الثالثة اضافة باستخدام الوقود المستخدم، واعادة نفس التجارب للمرحلة االولى مقیاس مستوى ضغط الصوت لقیاس الضوضاء المنبعثة من وعلى ) ٩٠°، ٤٥°، ٠بزوایا (محرك األحتراق وبثالثة اتجاھات ت المنبعث متر من مركز المحرك لمعرفة طبیعة الصو ١بعد . lighthillومطابقتھ مع نظریة الباحث مخطط لمقطع عرضي یوضح وضع العوازل حول المحرك ٤-الشكل .لقیاس شدة الضوضاء المنبعثة من المحرك النتائج والمناقشة.٣ ø)ثیر زاویة القیاس أت.١.٣ على شدة الضوضاء ( حرك تم رسم لبیان ومعرفة طبیعة الصوت المنبعث من الم angle) اتجاة الالقطة او االتجاھیةن ــبی )٧و ٦، ٥(العالقات of directivity) وجود یالحظ ،مع مستوى ضغط الصوت عند تغیر زاویة ،)مستوى ضغط الصوت(فارق طفیف في مقدار ن أوھذا یعني ،ولنفس عدد الدورات ،القیاس عند االحمال المختلفة lighthillحسب تعریف ي القطبحادأالمصدر المنبعث مصدر ° ٩٠ألنواع مصادر الضوضاء، ولذا تم تثبیت زاویة القیاس ن الضوضاء تزداد مع أ، مع مالحظة عمودي على اتجاه الجریان .زیادة عدد دورات المحرك عالقة مستوى ضغط الصوت مع عدد الدورات.٢.٣ العالقة بین مستوى ضغط الصوت مع ) ٨(یالحظ من الشكل والحمال مختلفة ولعدد دورات مختلفة، ،سرعة المكبسمتوسط ن یبین الشكل أ ،لنفس الدورة) من أقل حمل ألقصى حمل( ي تغیر في أن أوھذا یؤكد الضوضاء تزداد بزیادة عدد الدورات، إذ تزداد .سرعة المحرك تؤدي الى تغیر في مقدار الضوضاء م اثبات أن ت دراسةال ةالضوضاء بزیادة السرعة ، ومن خالل ھذ .یؤدي الى تغیر في مقدار الضوضاءأي تغیر في السرعة this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ 90 ، صفحة2، العدد 7مجلة الخوارزمي الھندسیة المجلد عادل محمود صالح 83 )2011( 86 العالقة بین زاویة الالقطة أو االتجاھیة ومستوى ضغط -٥الشكل .الصوت عند عمل المحرك بدون عازل العالقة بین زاویة الالقطة أو االتجاھیة ومستوى ضغط -٦الشكل .ند عمل المحرك بعازل واحدالصوت ع العالقة بین زاویة الالقطة أو االتجاھیة ومستوى ضغط -٧الشكل .الصوت عند عمل المحرك بعازلین العالقة بین مستوى ضغط الصوت وسرعة المحرك عند -٨-الشكل .عمل المحرك بدون اضافة ایثانول وبدون عزل مستوى ضغط الصوت مع الوقود المستخدمعالقة .٣.٣ ن اضافة الكحول تؤدي أ) ١١و ١٠ ،٩(یالحظ من االشكال ولكن ،الى زیادة مستوى ضغط الصوت عند نفس عدد الدورات ن اضافة الكحول ال تؤثر كثیرا على یعني أھذا و ،بنسبة قلیلة .مقدار الصوت المنبعث من المحرك شدة الضوضاء تأثیر وجود الجدار العازل على .٤.٣ أن الضوضاء تنخفض ) ١٤و ١٣، ١٢(یالحظ من االشكال بمقدار واضح باستخدام عازل الفلیین، وھذا یعني كفاءة عزل صوتي جیدة، وبالتالي یمكن االستفادة من ھذا العمل لبیان مقدار ثأثیر العزل على تقلیل الضوضاء الصادرة من المصدر على .لةالمستمع، وضمن المدیات المقبو العالقة بین مستوى ضغط الصوت وسرعة المحرك عند -٩-الشكل .ایثانول وبدون عزل% ١٠عمل المحرك باضافة this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ 90 ، صفحة2، العدد 7مجلة الخوارزمي الھندسیة المجلد عادل محمود صالح 83 )2011( 87 العالقة بین مستوى ضغط الصوت وسرعة المحرك عند -١٠-الشكل .ایثانول وبدون عزل% ٢٠عمل المحرك باضافة العالقة بین مستوى ضغط الصوت وسرعة المحرك عند -١١-كل الش .عمل المحرك بدون اضافة ایثانول وبعازل واحد العالقة بین مستوى ضغط الصوت وسرعة المحرك عند -١٢-الشكل .عمل المحرك بدون اضافة ایثانول وبعازلین ھیة ومستوى ضغط الصوت عند سرعة العالقة بین االتجا ١٣-الشكل .rpm 1700محرك العالقة بین االتجاھیة ومستوى ضغط الصوت عند سرعة ١٤-الشكل .، بدون اضافة ایثانولrpm 1700محرك العالقة بین االتجاھیة ومستوى ضغط الصوت عند سرعة ١٥-الشكل .ایثانول% ١٠ة ، باضافrpm 1700محرك this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ 90 ، صفحة2، العدد 7مجلة الخوارزمي الھندسیة المجلد عادل محمود صالح 83 )2011( 88 العالقة بین سرعة المحرك ومستوى ضغط الصوت عند -١٦-الشكل .ایثانول%) ٢٠و ١٠، ٠( عمل المحرك بدون عازل وبنسب خلط شدة الضوضاء ىتأثیر استخدام جدارین عل.٥.٣ تأثیر استخدام جدار الفلیین ) ١٦و ١٥(یالحظ من االشكال على شدة الضوضاء المنبعثة من ،راغ ما بینھماوجدار الزجاج والف زل بحیث تكون قیمة الضوضاء عوبیان ارتفاع كفاءة ال ،المحرك .ضمن المنسوب المستحب للمستمع االستنتاجات.٤ أن مصدر المنبعث للمحرك المستخدم ھو مصدر أحادي .١ .القطب الضوضاء بزیادة عدد الدورات، وھذا یعني ان اي تزداد.٢ ة المحرك تؤدي الى تغیر في مقدار تغیر في سرع .الضوضاء لى زیادة مستوى ضغط الصوت تؤدي إاضافة الكحول إن.٣ .ولكن بنسبة قلیلة ،عند نفس عدد الدورات اضافة الكحول كثیرا على مقدار الصوت المنبعث ال تؤثر .٤ .من المحرك ،الضوضاء بمقدار واضح باستخدام عازل الفلیین تنخفض.٥ .العزل الصوتي تزداد ن كفاءةأوھذا یعني ن یزید من كفاءة العزل، ویقلل من أتغییر نوع العازل یمكن .٦ .الضوضاء ضمن المنسوب المقبول من المستمع قائمة الرموز p ضغط الصوتn/m2 po ضغط الصوت المرجعيn/m2 s.p.l مستوى ضغط الصوت(db) t الزمنsec co سرعة الصوت في المحیط م المنتظ m/sec q المعدل الزمني لتولید واختفاء kg/m2secالكتلة لوحدة الحجم f i معدل القوى لوحدة الحجمn/m3 i,j األتجاھات قائمة الرموز الالتینیة ρ الكثافةkg/m3 kg/m3القیمة التذبذبیة للكثافة المصادر.٥ [1] sound transmission class, science and engineering encyclopedia version 2.1, 2005, on line report www.direcdelta.co.uk [2] robert adams, noise and directivity tests, honda eu2000i generators in single and parallel operation pincor 2000w contractor generator, 2006. [3] al-ati a i, a study of transmission of normal sound waves through a specific multimedia, m. sc. thesis, university of technology, baghdad, iraq, 2006. [4] guide to acoustics, dow chemical company kingdom of saudi arabia, 2006. on line report: http www.dow.com [5] reno n, 2007. a comparison of green and conventional diesel bus noise levels, noiseconv 2007, october 22-24. [6] berendt r d, "quieting a practical guide to noise control", government printing office washington, 1976. [7] jones a d and brown g l, determination of two stroke engine exhaust noise by the method of characteristics, journal of sound and vibration, vol. 90, no.4, 22 october 1983. [8] staniano m a, vehicle sound level reduction due to repair of defect exhaust system, noise control engineering journal issn 0736, vol.21, no. 2, 1983. [9] kantarelies c and walker j g, the identification and subjective effect of amplitude modulation in diesel engine exhaust noise, journal of sound and vibration, vol. 120, no. 2, 1988. [10] salih w m, the scientific technology to study the influence of noise characteristics for the energy exhaust system, degree of m. sc. thesis, university of technology, baghdad, iraq, 1999. [11] lighthill m j, on sound generated aerodynamically, i: general theory, procthis page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ 90 ، صفحة2، العدد 7مجلة الخوارزمي الھندسیة المجلد عادل محمود صالح 83 )2011( 89 royal soc, london, a211, ppp564-587, 1952. [12] ahmed h a, study of methanol alcohol addition influence on spark ignition engine performance and exhaust emission & noise, m. sc. thesis, university of technology, baghdad, iraq, 2010. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ adel mahmoud saleh al-khwarizmi engineering journal, vol. 7, no. 2, pp 83 90 (2011) 90 study of adding ethanol to gasoline effects on produced noise intensity of single cylinder spark ignition engine adel mahmoud saleh department of machines and equipments engineering/ university of technology email: adel196150@yahoo.com abstract since 1990 internal combustion engines and variable systems has been considered as emission. noise can be defined as undesirable sound, and in high levels it can be considered ahealth hazard. large internal combustion engines produce high levels of noise. in many countries there are laws restricting the noise levels in large engine rooms and fixed applications. locomotives engines have the minimum emission influence because of noise control techniques capability. in this paper study on a single cylinder internal combustion engine was conducted. the engine works by adding ethanol to gasoline, at variable speeds, without adding ethanol, and with adding 10 and 20% ethanol in volumetric ratio. using one sound insulator or two or without using sound insulator. the results show that noise increased with engine speed increase. adding ethanol didn't affect noise produced by engine. the study demonstrates that using one insulator is enough to reduce noise with high percentage. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ هشام حسن al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 1220 (2013) estimated outlet temperatures in shell-and-tube heat exchanger using artificial neural network approach based on practical data hisham hassan jasim department of mechatronics engineering/ al-khwarizmi college of engineering/ university of baghdad (received 4 june 2012; accepted 8 april 2013) abstract the objective of this study is to apply artificial neural network for heat transfer analysis of shell-and-tube heat exchangers widely used in power plants and refineries. practical data was obtained by using industrial heat exchanger operating in power generation department of dura refinery. the commonly used back propagation (bp) algorithm was used to train and test networks by divided the data to three samples (training, validation and testing data) to give more approach data with actual case. inputs of the neural network include inlet water temperature, inlet air temperature and mass flow rate of air. two outputs (exit water temperature to cooling tower and exit air temperature to second stage of air compressor) were taken in ann. 150 sets of data were generated in different days by the reference heat exchanger model to training the network. regression between desired target and prediction ann output for training , validation, testing and all samples show reasonably values are equal to one (r=1) . 50 sets of data were generated to test the network and compare between desired and predicated exit temperature (water temp. and air temp.) show a good agreement ( %.30± ). keywords: artificial neural network, shell-and-tube heat exchanger, outlet temperatures, training, validation and testing. 1. introduction heat exchangers are devices that facilitate the exchange of heat between two fluids that are at different temperatures while keeping them from mixing with each other. heat exchangers are commonly used in practice in a wide range of applications, from heating and air conditioning systems in a household, to chemical processing and power production in large plants. different heat transfer applications require different types of hardware and different configurations of heat transfer equipment. the most common type of heat exchanger in industrial applications is the shell-and-tube heat exchanger. analysis of heat exchanger needs some steps like the choice of a method of solution (lmtd or ntu) based on the type of application, consideration fitted with environment of work and determine the fouling factor and correction factor from figures or experimental correlation. all these steps give result with some error whene compared with actual case. a number of experimental and numerical researches on the heat exchanger characteristics have been conducted for several decades. jian-fei zhang [1] presented 3d numerical simulation of a whole heat exchanger with middle-overlapped helical baffles which is carried out by using commercial codes of gambit 2.3 and fleunt 6.3. the validation of the computational model is performed by comparing the total pressure drop and average nusselt number of the whole heat exchanger with experimental data. reasonably good agreement is obtained. yusuf ali kara[2] presented the program determines the overall dimensions of the shell, the tube bundle, and optimum heat transfer surface area required to meet the specified heat transfer duty by calculating minimum or allowable shell-side pressure drop. nasser ghorbani[3] presented an experimental investigation of the mixed convection heat transfer in a coil-in-shell heat hisham hassan jasim al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 1220 (2013) 13 exchanger. the calculations were performed for the steady-state and the experiments were conducted for both laminar and turbulent flow inside coil .the results indicated that the ε−ntu relation of the mixed convection heat exchangers was the same as that of a pure counter-flow heat exchanger. the computational intelligence (ci) techniques, such as artificial neural networks (anns), have been successfully applied in many scientific researches and engineering practices. several investigators have proposed (ann) modeling with experimental or theoretical work for thermal engineering application. g.n. xie[4]presented artificial neural network (ann) for heat transfer analysis of shell-and-tube heat exchangers with segmental baffles or continuous helical baffles. limited experimental data was obtained for training and testing neural network configurations. the maximum deviation between the predicted results and experimental data was less than 2%. comparison with correlation for prediction shows superiority of ann. dheerendra vikram singh[5] compare performances of three training functions (trainbr, traincgb and traincgf) used for training neural network for predicting the value of the specific heat capacity of working fluid. the comparison is shown on the basis of percentage relative error, coefficient of multiple determination r-square, root mean square error and sum of the square due to error. the goal of this study is to built artificial neural network based on actual data to training model of shell and tube heat exchanger by dividing the data to three samples (training , validation and testing data ) to give more approach data with actual case. two outputs (exit water temp. and exit air temp.) were taken in ann because of importance them for cooling tower and air compressor connected with the heat exchanger. 2. heat exchanger database modeling sufficient data samples are necessary for nn model development. it is almost needed to take more accuracy data from actual cases to represent any model. shell-and-tube heat exchanger working in dura refinery used as reference model to result sufficient data for nn training and testing. air represented one of the important working substance used in many devices in dura refinery especially in power service department. multi stage air compressor was used to produce pressurized air. when the air is inter to each stage of air compressor, its pressure and temperature will increase. therefore should be used heat exchanger to decrease air temperature before the next stage to safe the parts of air compressor. fig.(1) show the shell-and-tube heat exchanger use in practical work. heat exchanger have the following specification: mass flow rate of water is (7 kg/s) diameter of shell is (609.6mm), one pass flow of shell (for air flow), two pass flow of tube (for water flow), diameter of tube is (15.9mm), number of tube is (46), the tubes contain aluminum fins with (0.22mm) thickness, the material of shell and tube is carbon steel, and length of tube (2134mm). [6] the heat exchanger performance data with different state parameters are generated by the validated reference model. in total, 200 sets of data were generated in different days by the reference heat exchanger model. the data range used for neural network training and testing is listed in table (1). table 1, data range of input and output parameters. range input parameters co3828− iwt ) co165155− iat ) skg /4.23.2 − am• range output parameters co4838 − ewt ) co6454 − eat ) hisham hassan jasim al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 1220 (2013) 14 fig. 1. shell-and-tube heat exchanger use in practical work (power generation department in dura refinery). 3. input and output parameters proper selection of input and output parameters is the first step of nn model development shown in fig (2). input parameters for heat exchanger neural network modeling include inlet water temperature iw )t , inlet air temperature ia )t , air flow rate am• . output parameters include exit water temperature ew )t and exit air temperature ea )t . ew )t and ea )t are very important output parameters for two reasons, firstly because output parameters selection in this study refer to performance level of heat exchanger operation, secondly because the known ew )t necessary to calculate air flow rate needed to cool warm water in cooling tower connected with heat exchanger and the known ea )t important for calculate the change in water flow rate of heat exchanger to avoid the danger limits of air temperature exit when the air enter to next stage of air compressor. fig. 2. input and outlet properties of heat exchanger use in practical work with general dimension. 4. neural network modeling the type of neural network used in this study is the multilayer neural network (mlnn) with a feed forward back propagation learning rule. input vectors and the corresponding target vectors are used to train a network until it can approximate a function. a feed-forward network has a layered ( l ) structure as shown in fig.(3) . each layer consists of units which receive their input from units from a layer directly below and send their output to units in a layer directly above the unit. there are hisham hassan jasim al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 1220 (2013) 15 no connections within a layer. the in inputs are fed into the first layer of 1,hn hidden units. the input units are merely 'fan-out' units; no processing takes place in these units. the activation of a hidden unit is a function if of the weighted inputs plus a bias. the output of the hidden units is distributed over the next layer of 2,hn hidden units, until the last layer of hidden units, of which the outputs are fed into a layer of on output units. [7] fig. 3. a multi-layer network with l layers of units. depending on delta rule, the activation is a differentiable function of the total input, given by: [8]. …(1) in which …(2) where: =j number of element (neuron) j,.......,j 1= =k number of element (neuron) k,.......,k 1= =p input pattern vector =p ky the activation values of the network when input pattern vector p was input to the network. =p ks the input to a set of neurons when input pattern vector p is clamped. =p jy the activation values of element j of the network when input pattern vector p was input to the network; =jkw the weight of the connection from unit j to unit k =kθ the biases to the units. =f the activation function. to get the correct generalization of the delta rule we must set …(3) the error measure pe is defined as the total quadratic error for pattern (p) at the output units: …(4) where =o an output unit. =γ constant of proportionality. =∆p modified of pattern p. =p od the desired output of the network when input pattern vector p was input to the network. =p oy the activation values of the network when input pattern vector p was input to the network. …(5) where =p kδ product of two factors. one factor reflects the change in error as a function of the output of the unit and one reflecting the change in the output as a function of changes in the input. assume firstly. …(6) )( pp ksfky = k p jy j jkwp ks θ+∑= jk p jkp w ew ∂ ∂ −=∆ γ ∑ = −= on p o p o p )yd(e 10 2 2 1 p j p kjkp yw δγ=∆ )s(f)yd( p o p o p o p o −=δ ok = hisham hassan jasim al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 1220 (2013) 16 and secondly assume where a hidden unit ..(7) equations (6) and (7) give a recursive procedure for computing theδ 's for all units in the network, which are then used to compute the weight changes according to equation (5). this procedure constitutes the generalized delta rule for a feed-forward network. working in back-propagation should by used the all above equations and the steps of solution are clarified in the following. when a learning pattern is clamped, the activation values are propagated to the output units, and the actual network output is compared with the desired output values, we usually end up with an error in each of the output units. we have to bring the error to zero. the application of the generalized delta rule thus involves two phases: during the first phase the input x is presented and propagated forward through the network to compute the output values p oy for each output unit. this output is compared with its desired value od , resulting in an error signal p oδ for each output unit. the second phase involves a backward pass through the network during which the error signal is passed to each unit in the network and appropriate weight changes are calculated. there are generally seven steps in the training process working in back propagation: [9] 1. start with random weights for the connections 2. select an input vector x from the set of training samples 3. the weight of a connection is adjusted by an amount proportional to the product of an error signalδ , in the unit k the input and the output of the unit j are received sending this signal along the connection. 4. calculate the error signal after choice the activation function. 5. the error signal for a hidden unit is determined recursively in terms of error signals of the units to which it directly connects and the weights of those connections. 6. the learning procedure requires that the change in weight is proportional to w e p ∂ ∂ . true gradient descent requires that infinitesimal steps are taken. the constant of proportionality is the learning rateγ . 7. make the change in weight dependent of the past weight change by adding a momentum term: …(8) where =α modified weight connection. =t time. 5. neural network training in artificial neural network all data are divided to three kinds of samples. the first kind (training) presented to the network during training, and the network is adjusted according to its error. the second kind (validation) used to measure network generalization, and to halt training when generalization stops improving. the third kind (testing) has no effect on training and so provides an independent measure of network performance during and after training. [10] agood network should includ small mean square error (mse) for training data performance and validation data performance. 150 sets of data were generated by the reference heat exchanger model use to train the network. here, the neural network with 1-3 layers (hidden layer), 2-16 neurons is studied and results mean square error for training and validation are provided in table ( 2 ). it 'is clear that 3 layers with 3 neuron ( iw )t , ia )t and am• ) in input layer , 16 neurons in hidden layers ,and 2 neuron ( ew )t and ea )t ) in output layer have less error approach to zero. )t(wy)t(w jk p j p kjk ∆+=+∆ αγδ1 hk = ∑ = = on o ho p o p h p h w)s(f 1 δδ =h hisham hassan jasim al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 1220 (2013) 17 table 2, results of neural networks. no. of layer no. of neuron type of (mse) 1 2 3 2 performance training validation training 5.9*10^-8 9.1*10^-8 8.1*10^-9 5.5*10^-9 5.6*10^-12 5.4*10^-13 3 performance training validation training 1.5*10^-9 8.3*10^-10 3.2*10^10 2.1*10^10 6.2*10^-12 5.8*10^-13 4 performance training validation training 5*10^-10 9.5*10^-10 2.4*10^-11 1.65*10^-11 7.1*10^13 8.2*10^14 6 performance training validation training 4.3*10^-11 1.4*10^-11 1.34*10^-11 1.24*10^-12 9.2*10^-15 6.6*10^-16 8 performance training validation training 8*10^-11 2*10^-11 6.2*10^-11 2.3*10^12 7.3*10^-16 9.2*10^-17 10 performance training validation training 9.8*10^-11 2.4*10^-11 3.8*10^-12 1.2*10^-12 8.5*10^-17 1.2*10^-18 12 performance training validation training 3.5*10^-11 1.2*10^-11 4.1*10^-14 8.1*10^-13 3.5*10^-19 1.8*10^-19 14 performance training validation training 2*10^-12 4*10^-11 8.2*10^-14 3.2*10^-14 7.4*10^-20 4.9*10^-19 16 performance training validation training 9.6*10^-12 5.2*10^-11 6.1*10^-16 8.2*10^-15 2.33*10^-21 5.23*10^-19 the goal of training is to find an optimum answer of network. fig. (4) show the training, validation and testing graph of developed network with 3 layers and 16 neurons. the graph resulted show a very good performance (very small mean square error) after 472 attempts. fig. (5) illustrate regression between desired target and prediction ann output for training , validation, testing and all samples. all outputs seem to track the targets reasonably well and regression values are equal to one (r=1). hisham hassan jasim al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 1220 (2013) 18 ew )t ea )t fig. 4. the best training fig. 5. regression between desired target and prediction ann output for training, validation, testing and all samples. 6. neural network testing this study used 50 sets of data were that generated by the reference heat exchanger model to test the network .the results shown in fig. ( 6 ) illustrate the good agreement ( %.30± ) between desired and predicated exit temperature (water temp. and air temp.) from heat exchanger. ew )t ea )t ew )t ea )t ew )t ea )t hisham hassan jasim al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 1220 (2013) 19 fig. 6. desired and predicated output data for testing neural network 7. conclusion this paper presents (ann) modeling approach to the steam condenser performance. experiment were carried out to validate the ann model. practical data was obtained from heat exchanger operation in dura refinery and the data was divided to three samples (training, validation and testing data). two outputs (exit water temp. and exit air temp.) were taken in ann. after study 1-3 layers with 2-16 neuron, with back propagation algorithm, the training and testing of the results were carried out and the output of network is created. three layers with 16 neurons had the best answer and used in this paper. comparing target data with experiment results of exit water temperature and exit air temperature showed the all outputs seem to track the targets reasonably well and regression values are equal to one (r=1) . compared with experiment results the exit temperatures for water and air drops predicted by the testing ann is ± 0.35% of data. all deviation falls into %1± . with artificial nn exit temperatures for water and air can be found without need to thermal heat exchanger analysis. the result of this study helps researchers to study the thermal performance of devices (cooling tower and air compressor) connected with heat exchanger. 8. references [1] jian-fei zhang, ya-ling he, wen-quan tao (2009) "3d numerical simulation on shelland-tube heat exchangers with middleoverlapped helical baffles and continuous baffles – part i: numerical model and results of whole heat exchanger with middleoverlapped helical baffles" international journal of heat and mass transfer 52/ 5371– 5380. [2] yusuf ali kara, ozbilen guraras (2004)"a computer program for designing of shell-andtube heat exchangers" applied thermal engineering 24/ 1797–1805. [3] nasser ghorbani, hessam taherian, mofid gorji, hessam mirgolbabaei (2010) "an experimental study of thermal performance of shell-and-coil heat exchangers" international communications in heat and mass transfer 37 / 775–781. [4] g.n. xie, q.w. wang *, m. zeng, l.q. luo (2007) "heat transfer analysis for shell-andtube heat exchangers with experimental data by artificial neural networks approach" applied thermal engineering 27 / 1096–1104. [5] dheerendra vikram singh , govind maheshwari, ritu shrivastav(2011) "neural network – comparing the performances of the training functions for predicting the value of specific heat of refrigerant in vapor absorption refrigeration system" international journal of computer applications (0975 – 8887) volume 18– no.4. [6] design operation sheet with practice data from dura refinery. [7] rojalina priyadarshni, nillamadhub dash, tripti swarnkar, rachita misra(2010)" functional analysis of artificial neural network for database classification" ijjct, vol 1(2,3,4), pp 49-54. [8] ben krose , patrick van der smagt "an introduction of neural networks" eighth edition november 1996. [9] m. sen, k.t. yang, (2000)"applications of artificial neural networks and genetic algorithms in thermal engineering" , crc handbook of thermal engineering, crc press, boca raton, fl, 2000. [10] m. jalili-kharaajoo, b.n. araabi, "neuropredictive control of a heat exchanger: comparison with generalized reductive control", ieee trans. (2003) 675–678. )2013( 1220 ، صفحة2، العدد9مجلة الخوارزمي الھندسیة المجلد ھشام حسن جاسم 20 انبوب باستخدام الشبكة –تخمین درجات الحرارة الخارجة من مبادل حراري نوع قشرة اعتمادا على معلومات تطبیقیة العصبیة الصناعیة ھشام حسن جاسم جامعة بغداد /كلیة الھندسة الخوارزمي / قسم ھندسة المیكاترونكس الخالصة تقال الحرارة لمبادل حراري وھو من األجھزة واسعة االستخدام في محطات تولید القدرة ھدف الدراسة ھو تطبیق الشبكة العصبیة لتحلیل ان اعتمدنا أشھر طریقة للتدریب وتعلیم .النتائج العملیة تم الحصول علیھا من مبادل حراري یعمل في قسم تولید الطاقة داخل مصفى الدورة.والمصافي للحصول على أفضل تقارب ) اختبار تصدیق، تدریب،(خالل تقسیم النتائج العملیة الى ثالثة أقسام من back propagation algorithmالخوارزمیة وھي قیم اإلدخال للشبكة العصبیة ھي درجة حرارة الماء الداخل و درجة حرارة الھواء الداخل ومعدل تدفق الھواء أما قیم اإلخراج فھي درجة . مع الحالة الحقیقیة قراءة تم أخذھا من المودیل في أیام عمل مختلفة لتدریب الشبكة ١٥٠. التبرید ودرجة حرارة الھواء الخارج لضاغط الھواءحرارة الماء الخارج لبرج قراءة تم أخذھا الختبار مدى دقة الشبكة ٥٠، مقارنة نتائج الشبكة مع القیم العملیة وبأقسامھا التدریب والتصدیق واالختبار بینة تقارب عالي جدا. العصبیة نة تقارب ودقة العصبیة في ھذه الدراسة من خالل مقارنة درجات حرارة الخروج للماء ودرجة حرارة الخروج للھواء الناتجة من الشبكة والمودیل العملي بی ). ±30.%(یث بلغت نسبة الخطأ بحدود معقولة ح final al-khwarizmi engineering journal al-khwarizmi engineering journal, vol, 1, no.1,pp ١٠١ -١١٦ , (2005) ١٠١ the effect of oil and filer contents on the porosity of lead acid battery separators produced from polyethylene dr. malek mostafa mohammed* zyad rafa'a zair *biochemical engineering dept./ al-khwarizmi engineering college/ university of baghdad abstract: in this investigation a high density polyethylene (hdpe) was used as a substitute to polyvinylchloride in the production of lead acid battery separators. this has been achieved by preparing mixtures of different percentages of the feed materials which include a high density polyethylene (hdpe) locally produced, filler materials such as silica and oils such as dioctylphthalate (dop) or paraffin which were added to the mixture to improve the final properties of the separator. the materials were compounded by two roll-mills under the same conditions. the following parameters are involved: 1studying the use of a high density polyethylene as a binder to film components with (15-30) wt.%. 2studying the use of finely divided silica sand with (25-45) wt.% as a medium to oil adsorption. 3studying the use of two type plasticizers (paraffin or dop) with (35-55) wt. %. as a creative medium to films porosity. the best results of the feed materials in the mixture were selected so as to give the highest porosity using 15 wt. % pe, 30 wt. % filler, and 55 wt. % oil. it has been found that the films with dop oil give higher porosity. keyword: lead acid battery separator, polyethylene, film, porosity. introduction: battery separator is the active component in the battery and plays an important roll to the cycle life and performance of the battery. it is made of thin sheet electrically insulating porous materials used as spacers between the plates (positive & negative) to prevent short circuit buckling of them while freely permitting to the ions in current to flow through the separator, absorb mechanical forces to reduce the positive action mass, they also act as barriers to the transport of active materials between the plates and prevent dendrite formation (1,2). broadly there are two categories of lead acid battery separators skeletal and fiber structure separators, as their name imply skeletal separators are made of materials have a rigid inner structure such as polymers that has been fused by heat or chemical action and is mixed with filler typically precipitated silica, these separators are usually available with ribs which enable the separator to create an inter plate spacing while keeping overall separator mass to a minimum, an example of this kind of separators is the well known polyethylene type of material, the second class encompasses all those separators that have fibers as their basic material these fibers can be organic or inorganic and they can be found together with a resin or be laid together loosely without a binder, both types of separators can be made available in sheet or in rolls depending on flexible and mechanically strong components of the battery (3). malek m. mohammed et al. / al khwarizmi engineering journal, vol., no. 1, pp 101-116 (2005) ١٠٢ the present work can be divided to the following items: 1. studying the effect of the addition a high density polyethylene as a binder on separator properties. 2. studying the effect of the addition a filler as oil adsorbed on separator properties. 3. studying the effect of the usage of two types of plasticizers on the final properties of separator. theory: according to the double sulfate theory(4) which proposed by gladstone and traube in 1882 the basic current generation process taking place in the lead acid batteries on the positive and negative electrode during charge and discharge may be written as the following reactions: pbo2 +3h++ hso4 +2e pbso4 +2h2o (+) …(1) pb + hso4 pbso4 + h++ 2e (-) . ...(2) the net process while doing process is expressed by the following reaction: pbo2 +pb +2h2so4 2pbso4+ 2h2o … (3) in this theory during the discharge of battery on both electrodes lead sulfate is formed due to the reduction of pbo2 on the positive electrode and the oxidation of spongy lead on the negative electrode. kiseleva and kabanov had studied the mechanism of the anodic evolution of oxygen on lead dioxide in sulfuric acid in detail and the rate of oxygen evolution is limited by the discharge step as: h2o oh (ads) + h+ + e . ... (4) the self-discharge of the positive plate may be related to the oxidation of separator materials pbo2 + (oxidisable product in separator) + h2so4 pbso4 + (oxidized product of separator) + h2o ... (5) however in modern batteries the separator used made from materials which are practically not oxidized under the conditions of the positive electrode working and its reaction. during the anodic polarization of lead alloys in addition to the oxidation of lead other components of alloys such as antimony also undergo oxidation; the oxidation of antimony apparently proceeds according to the reaction: sb + h2o sbo+ + 2h+ + 3e . ...(6) also an extreme sulfation of the negative plate is observed when the grid of the positive plate in battery contains an abnormally large percentage of antimony which then getting into the negative electrode across the pores of separator and lower the hydrogen over voltage(4). another one of the causes of short circuits at the edges of the plates and through the separator, is basically connected with an accumulation of sludge at the bottom of battery case owing to dissolution of the positive active mass then sludge particles are transferred electrophoretically to the negative plates lead to swelling of the active mass which penetrates the pores of the separators if it has sufficiently large dimensions, and appearance of bridges round the separators (5). in general that size of the pores must be small enough to prevent the passage of solid materials such as lead or lead sulfate crystals and to hinder the passage of antimony ions which frequently are introduced into the electrolyte by the positive plate and which migrate to the negative plate and there by shorten the life of the malek m. mohammed et al. / al khwarizmi engineering journal, vol., no. 1, pp 101-116 (2005) ١٠٣ battery,but sufficiently large to permit the electrolyte to pass through (6). experimental work: 1-materials used: polymer high density polyethylene was used as a binder to the components of filler and plasticizer for producing films which is originally used for film applications, it was supplied by the state company for petrochemical industries in basrah in the form of pellets varies in particle size. silica sand (filler) local quartz silica sand is supplied by the state company for geological survey and mining, this type of filler was extracted from urthumma quarry in rutba area. in the present investigation it was used as adsorbent for plasticizer employed, for size reduction jet milling technique was used for this type of filler and the dust size which represented the finest particle size of the process were collected on the back filter of the system. plasticizers in the present work two kinds of plasticizers were used paraffin oil and dioctylphthalate for reaching to the best result of porosity and electrical resistance. with worth mentioning these oils were shared with some of experiments and extracted at the same conditions using n-hexane as a solvent. 2-compounding and processing these processes were done with using of compounding laboratory equipment which known as tworoll mills (figure(1)). this machine is made of two rolls of iron metals rotates one against each other at speed of operation 30 rpm and the length of each one (12) inch and the diameter (9) inch, the feed charge in each stage of compounding was (150 to 200)g based on the total ingredients. the pellets of polyethylene were compounded with high pressure exerted by two rolls compression about 800 psi. oil is added gradually to the filler (silica) with continuous mixing then blended with the polyethylene. the mixture were introduced into a roll mill where rolls are heated by hot water of highly elevated temperature about 150 oc to be able to melt the polyethylene in the mixture for (10-15) minute to obtain finished sheet with thickness (0.2-0.35) mm. the arrangements of compositions for the experiments are tabulated in tables (1) and (2). solvent extraction process on a laboratory scale and for removing of processing oil from the films (to produce separator with a suitable degree of porosity), the extraction process was done with using of 250 ml round bottom flask, a thermometer of 250 oc in one neck (figure(2)) and a reflecting cooling water glass condenser (24 mm diameter and 470 mm height) fitted to the other for solvent vapor condensation, hot plate with magnetic stirrer for increasing of washing efficiency to the films where solvent rotate continuously, water bath container used to control and regulate the temperature of the solvent. the oil extracted can be calculated as: the oil extracted (%) = (woil0 woil1)/woil0 x 100 .. (7) solvent recovery system a non fractionated distillation(7) was used in laboratory distillation process, the distillation apparatus (figure(3)) was employed consist of heating mental of 1.2 kw was connected to the voltage regulator to provide the input power, the heating mental was capable of 250 ml round bottom flask, a thermometer of 250 oc, and a glass condenser (35 mm diameter malek m. mohammed et al. / al khwarizmi engineering journal, vol., no. 1, pp 101-116 (2005) ١٠٤ and 500 mm long) is connected with round bottom flask by help of glass connector as a divider using water as a cooling media. volume porosity films with 40×40 mm2 cross section areas and 0.25 mm thickness were extracted, placed in an oven of 70 °c for about 60 minute to remove the moisture from them. the samples then were put in an evacuated dissecator for 24 hr to reach the room temperature, the film were weighed (w1) in an electrical balance (4-digits) then immersed in a distilled water for saturation at room temperature for 60 min and weighed (w2) after that, therefore, the pore volume (vp) of the film can be represented as: vp = (w2 – w1)/ρw . ..(8) the total external volume of the film (vf) was measured using mercury porosimeter (ruska instrument corporation) available in the department of petroleum engineering. porosities of the films were found by applying the equation (8,9): p (%) = vp /vf x 100 . ..(9) the experimental results of oil extracted and porosity are tabulated in table (3). results and discussion: the effect of temperature on the oil extraction: the effect of the temperature at which the oil extraction took place on the extracted and remaining oil are shown in fig.4, it has been observed that with the increase of temperature from 25 to 65 0c, the increase of oil extracted were not significant. this is because of a high solubility of the plasticizer in n-hexane. at 65 0c the percentage of extraction did not exceed 1% compared at 25 0c. therefore it is more economical to carry out the extraction at 25 0c. the effect of time on the oil extraction: the effect of extraction time on the oil extracted is shown in fig.5. it is shown that as the sequence of extraction time (30,60,90,120) minutes, the extracted oil is (45.26,45.36,45.36,45.40)% respectively. therefore a slight increase in the extracted oil with time could not be considered as a significant factor in time selection for best results (i.e., most of the oil feed in the original film mixture were dissolved in the early time of extraction). again this is because of a high solubility of the plasticizer in n-hexane. according to theses results the increase of extraction time above 60 minutes is not necessary and this is considered the recommended time for this study. the effect of separator components on porosity: the capacity of lead acid battery can be improved by increasing of the porosity, to some level, beyond which the life time of battery may be reduced. from figs.6 to 8 it has been shown that by increasing of the oil content the oil extracted increases too. the increase of oil content leads to an increase of the oil in the voids between the filler particles and on their surfaces which is extracted latter. which can be explained that any increase in the oil content can be depleted in the extraction step. as seen in figs.6 and 7 the percentage oil extracted with dop films is slightly higher than paraffin films. this is because dop solubility in n-hexane is higher. the changing of filler content of the film on the extracted oil is malek m. mohammed et al. / al khwarizmi engineering journal, vol., no. 1, pp 101-116 (2005) ١٠٥ shown in fig.9. it is clear from this figure that the increase in the filler content cause an increase in the oil extracted from the film. this because the aim of adding the filler is to form a surface where the oil can be spread on. thus the increase in filler content leads to increase in the oil content and then increase in the oil extracted. figures.10, 11, and 12 show that as of the oil feed content increases the porosity of the film will increases. the extraction of the oil from the mixture led to the formation of pores and creating inner irregular tortuous channels which is responsible for the increase in the porosity. although the increase in the oil content percentage on the expense of the polyethylene leading to an increase in the porosity, it is worth mentioning that the less polyethylene content the less the number of chains binding where the filler grains will increases the wettability and may lead to more open pores and channels making the penetration and diffusion of the solvent through the film more easier. this behavior were also confirm through fixation of oil feed percentage, decreasing in the feed polymer percent, and increasing in the filler percentage where the oil is adsorbed and distributed over higher amount of filler particles leading to an increase in the number of the inner channels occupied by oil which is going to be opened by extraction process, the results were an increase in the porosity. by comparison between the films made of paraffin oil and that made with dop oil it had been found that the porosity of the first is less than that of the latter. this is explained previously, the higher solubility of dop than paraffin oil in organic solvents (i.e.,. oil extracted from dop samples is rather higher than paraffin oil samples). an increase in porosity is gained as the filler content increases (fig.13). again this behavior was explained earlier, that is the increases in filler content leads to increase in the oil content, thus increase the porosity of the film. conclusions: 1the best conditions for oil extraction were 60 minutes at 25 0c. 2the decrease in oil extracted cause a reduction in the porosity. 3the increase of the oil feed percent in the film mixture from (35 to 55) wt. % led to a noticeable increase in porosity after its extraction through creation of pores. 4using dop oil in film mixture gives rather better results of porosity. 5the increase in (polymer/filler) ratio results in the reduction in films porosity. 6reduction in the polymer percent from (30 to 15) wt.% with increasing or fixation of filler feed percent will lead to porosity increase. 7the best percentages of film mixture was 15 wt.% pe, 30wt.% filler, and 55 wt.% oil to give the best porosity. nomenclature: p porosity vf film volume measured by mercury porosimeter (cm3) vp pore volume measured by water impregnated (cm3) w1 weight of dry film after extraction. (g) w2 weight of film impregnated with water. (g) woil0 weight of film before extraction. (g) woil1 weight of dry film after extraction. (g) ρw density of water (g/cm3) malek m. mohammed et al. / al khwarizmi engineering journal, vol., no. 1, pp 101-116 (2005) ١٠٦ references: 1. vinal, c. w., "storage batteries", 4th. edition. wiley, new york, 1962.(p51). 2. isaacson, m.j., giovannoni, r.t., choi, w. m., and kung, j.k., "battery separator for recombinant batteries" ep. patent no. 0466302a1; april. 24, 1991.(pp14) 3. vincent, c.a., and scrosaci, b., "modern batteries", arnold, 1997.(p150). 4. dasoyan, m.a., and aguf, i. a.," the lead accumulator", asia publishing house, 1968. 5. dasoyan, m.a., and aguf, i. a., "current theory of lead –acid batteries", technology limited, england, 1979.(p347). 6. larson, d.w., and kehrednor, c. l., "battery separator" u.s. patent, no. 3351495; november. 7, 1967. 7. nelson, w.l., "petroleum refinery engineering ", 4th edition, mcgraw-hill, new york, 1958.(p465). 8. bode, h., "lead acid batteries", a wileyinterscience publication, new york, 1977. 9. doi, y., tachikawa,o.m., kaneko, s., and hanamura,t., "microporous film battery separator" u.s. patent, no. 4210709; july. 1, 1980.(pp26). malek m. mohammed et al. / al khwarizmi engineering journal, vol., no. 1, pp 101-116 (2005) ١٠٧ table (1): the arrangement of paraffin films experiments. set. no exp. no polyethylene wt. % silica wt.% paraffin oil wt.% one 1 30 30 40 2 25 30 45 3 20 30 50 4 15 30 55 two 5 30 35 35 6 25 35 40 7 20 35 45 8 15 35 50 three 9 20 25 55 3 20 30 50 7 20 35 45 10 20 40 40 four 1 30 30 40 6 25 35 40 10 20 40 40 11 15 45 40 table (2) the arrangement of dop films experiments. set. no exp. no polyethylene wt. % silica wt.% dop wt.% one 1 30 30 40 2 25 30 45 3 20 30 50 4 15 30 55 two 9 20 25 55 3 20 30 50 7 20 35 45 10 20 40 40 three 1 30 30 40 6 25 35 40 10 20 40 40 11 15 45 40 malek m. mohammed et al. / al khwarizmi engineering journal, vol., no. 1, pp 101-116 (2005) ١٠٨ table (3) results of oil extraction from dop & paraffin films. set. no exp. no oil content wt. % oil extracted wt.% porosity % paraffin dop paraffin dop one 1 40 34.69 35.58 28.51 29.71 2 45 40.58 42.26 33.46 34.93 3 50 45.30 47.07 39.74 41.53 4 55 49.42 51.38 45.99 48.17 two 5 35 32.47 …….. 30.36 …….. 6 40 35.69 36.79 32.59 33.98 7 45 40.45 41.99 38.14 39.70 8 50 46.74 …….. 43.22 ……. three 9 55 48.88 50.73 41.97 43.91 3 50 45.30 47.07 39.74 41.53 7 45 40.45 41.99 38.14 39.70 10 40 36.90 38.21 36.52 38.01 four 1 40 34.69 35.58 28.51 29.71 6 40 35.69 36.79 32.59 33.98 10 40 36.90 38.21 36.52 38.01 11 40 38.35 39.57 39.03 41.38 malek m. mohammed et al. / al khwarizmi engineering journal, vol., no. 1, pp 101-116 (2005) ١٠٩ hooper control panel molten materials doctor knife thickness regulator support plate wind roll front roller product film back roller fig(1) schematic diagram of compounding & processing machine. fig(2) schematic diagram of extraction process malek m. mohammed et al. / al khwarizmi engineering journal, vol., no. 1, pp 101-116 (2005) ١١٠ 45 45.1 45.2 45.3 45.4 45.5 45.6 45.7 45.8 ٤٥.٩ ٤٦ 20 25 30 35 40 45 50 55 60 65 70 temperature oc oil extraction at 60 min o il ex tr ac te d % figure (4): the effect of the solvent temperature on the film oil extracted. figure (3): schematic diagram of solvent recovery method malek m. mohammed et al. / al khwarizmi engineering journal, vol., no. 1, pp 101-116 (2005) ١١١ ٤٥.٢٤ ٤٥.٢٦ ٤٥.٢٨ ٤٥.٣ 45.32 45.34 45.36 45.38 45.4 45.42 ٠ ٢٠ ٤٠ ٦٠ ٨٠ 100 120 140 time (min) oil extraction at 25 c o il ex tr ac te d % figure (5): the effect of the extraction time on the film oil extracted. 25 30 35 40 45 50 55 35 40 45 50 55 60 oil content wt.% paraffin films with 30 % feed filler dop films with 30 % feed filler o il ex tr ac te d % figure (6): the effect of the oil feed percent on the film oil extracted with constant filler percent. malek m. mohammed et al. / al khwarizmi engineering journal, vol., no. 1, pp 101-116 (2005) ١١٢ 25 30 35 40 45 50 55 35 40 45 50 55 60 oil content wt.% o il ex tr ac te d % paraffin films with 20 % pe dop films with 20 % pe figure (7): the effect of the oil feed percent on the film oil extracted with constant polymer feed percent. 25 30 35 40 45 50 30 35 40 45 50 55 oil content wt.% o il ex tr ac te d % paraffin films with 35 % feed filler figure (8): the effect of the oil feed percent on the film oil extracted with constant filler percent. malek m. mohammed et al. / al khwarizmi engineering journal, vol., no. 1, pp 101-116 (2005) ١١٣ 34 35 36 37 38 39 40 25 30 35 40 45 50 filler wt.% o il ex tr ac te d % paraffin films with 40 % feed oil dop films with 40 % feed oil figure (9): the effect of filler content on the extraction efficiency with constant oil feed percent. 20 25 30 35 40 45 50 35 40 45 50 55 60 oil content wt.% po ro si ty % paraffin films with 30% filler dop films with 30% filler figure (10): the effect of the oil feed percent on the film porosity with constant filler percent. malek m. mohammed et al. / al khwarizmi engineering journal, vol., no. 1, pp 101-116 (2005) ١١٤ 30 32 34 36 38 40 42 44 46 35 40 45 50 55 60 oil content wt.% po ro si ty % paraffin films with 20% pe dop films with 20 % pe figure (11): the effect of the oil feed percent on the film porosity with constant polymer feed percent. 25 27 29 31 33 35 37 39 41 43 45 30 35 40 45 50 55 oil content wt.% po ro si ty % paraffin films with 35 % filler figure (12): the effect of the oil feed percent on the film porosity with constant filler percent. malek m. mohammed et al. / al khwarizmi engineering journal, vol., no. 1, pp 101-116 (2005) ١١٥ 25 27 29 31 33 35 37 39 41 43 45 25 30 35 40 45 50 filler wt.% po ro si ty % paraffin films with 40 % feed oildop films with 40 % feed oil figure (13): the effect filler content on the film porosity with constant oil feed percent. malek m. mohammed et al. / al khwarizmi engineering journal, vol., no. 1, pp 101-116 (2005) ١١٦ تأثير المكونات من الزيت والماألت في الفراغية لعوازل بطاريات الرصاص السائلة المصنوعة من البولي اثيلين مالك مصطفى محمد زياد رافع زاير.د جامعة بغداد/كلية هندسة الخوارزمي/قسم هندسة الكيمياء االحيائية :الخالصة يتناول هذا البحث دراسة استخدام البولي اثيلين المنتج محليا في تصنيع عوازل بطاريات الرصاص السائلة كبديل اقتصادي عن عوازل البولي فينيل كلورايد المستخدمة من قبل الشركة العامة . لصناعة البطاريات وكذلك عن عوازل البولي اثيلين المستوردة تم ذلك من خالل تحضير خلطات بنسب مختلفة للمواد الداخلة والتي تشمل البولي اثيلين عالي إلىالتي تضاف )الدوب( وثنائي اوكتايل الفثاليتافين امثل السليكا، زيوت مثل البار الكثافة ، مواد مالئة two – roll millالخلطة لتحسين الخواص النهائية للعازل ، ثم تشكيله بواسطة ماكنة الخلط والمعروفة .بظروف عملية ثابتة تضمن البحث المحاور آالتية %. ٣٠-١٥بنسب وزنية العالي الكثافة البولي اثيليناستخدام %.٤٥-٢٥إضافة مادة السيليكا بنسب وزنية %.٥٥٣٥مثل زيت البرافين و الدوب بنسب وزنية ) لعمل الفراغات(تأثير إضافة مادة ملدنة النسب للمواد الداخلة في الخلطات والتي أعطت أعلـى درجـة مـن المسـامية أفضلتم تحديد مـن ) % ٥٥( و% ) ٣٠( مواد مالئة بنسبة ,) %١٥( العالي الكثافة بنسبة لين ياستخدام البولي اثب الزيت ، لقد وجد بان النماذج مع زيت ثنائي اوكتايل الفثاليت تمتاز بدرجة مسامية أعلى عن نماذج زيت .البرافين final al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 1, no.1, pp 64-75 (2005) ٥٢ al-khwarizmi engineering journal al-khwarizmi engineering journal, vol.1, no.2,pp 52-63, (2005) the timoshenko three-beams technique to estimate the main elastic moduli of orthotropic homogeneous materials dr. kamal k.m. saify * dr. adnan n.j. al-temimy** dr. muhsin j.j. *** *the technical college-baghdad / department of dies & tools. ** mechanical engineering dept./college of engineering./ university of baghdad *** mechanical engineering dept./ college of engineering/ university of al-nahrain (received 11 december 2004, accepted 11 february 2005) abstract: a new developed technique to estimate the necessary six elastic constants of homogeneous laminate of special orthotropic properties are presented in this paper for the first time. the new approach utilizes the elasto-static deflection behavior of composite cantilever beam employing the famous theory of timoshenko. three extracted strips of the composite plate are tested for measuring the bending deflection at two locations. each strip is associated to a preferred principal axis and the deflection is measured in two orthogonal planes of the beam domain. a total of five trails of testing is accomplished and the numerical results of the stiffness coefficients are evaluated correctly under the contribution of the macromechanics and the approximate bending theory. to insure the validity of the new approach, separate individual tensile tests are performed, and the corresponding results are compared. excellent agreements are obtained between the different approaches. the ease, simple and accurate predictions are well confident by the new technique. keywords: timoshenko ,beam, composite beam. 1. introduction the development of composite materials offers great potential in advanced civilian and non-civilian structural applications since the late thirties of the last century [1,2] and still now in rapid progress and evolution [3,4]. the recent century began with a new technological development of the “smart” composite structures [5,6,7] where a large strength-to-weight ratio is achieved, besides the ability to react actively to disturbance forces while maintaining structural integrity. the assignment of the mechanical engineering properties, of such materials, are strongly demanded for design and behavior analysis. the orthotropic elastic constants (total nine in number) represent an important set of those properties. starting with the familiar young, shear moduli and poisson’s ratio, the traditional static tensile test satisfies, to some level, the mentioned objective but involves uncertainty of the results (due to the localized deformation near the end fixture of the tensile sample (see ref.[8], chap. micromechanics) as well as the weak and simple base theory it adopts where the transverse shear effects are ignored as usual [8,9]), and also the relative cost of the test requirements (the available of tensile m/c and minimum three kamal k.m. saify./ al-khwarizmi engineering journal ,vol.1, no. 2,pp 52-63 (2005) ٥٣ samples to be distracted later). moreover, the traditional test is not able to determine more than four elastic constants in its best conditions (refer to [8]). the theoretical and experimental attempts of tsai[9] and nextly halpin and tsai[10] in the static micromechanics of composites, was found satisfactory if the pre-limitations in analysis were released. their formulations require that the physical and geometrical properties of the composite constituents as well as a suggestion of two new factors insurt in the formulae, all ought to be prepared in advance. again only four elastic constants could be obtained by these approaches. dynamic tests, were firstly conducted by goens[11] to determine the shear modulus of an isotropic bar under torsion. later on, the two elastic constants (young and shear moduli) were obtained by pickett[12], hasselmen [13] and spinner & teff[14] using two independent tests, the bending vibration and torsional ones. rubben & scharr[15] applied excellently both the static tensile test and torsional vibration test to estimate the nine elastic constants of composite using three chosen samples for the two tests, one of which its fabrication procedure was seemed difficult to be achieved and required much care and accuracy. deobald & gibson [16] used the classic orthotropic plate theory of kerishoff to compute the four elastic constants employing the new modal analysis technique (mat) [17]. saify & al-temimi[18] were the first who succeeded to obtain the two “effective” elastic moduli by one test of flexural vibrations of prismatic bar. recently reference [19] presented a developed “three theories technique (ttt)” to determine all the elastic constants set of anistropic material employing the mat and basing theoretically upon his “exact” orthotropic simply-supported plate theory from levinson[20] first concept of the exact isotropic plate theory. the conditions, required to make this approach successful, are: a test rig for sample boundary supporting and the set-up instrumentation of the applied mat. it seems, generally, that a chosen approach, to determine the orthotropic elastic constants of a composite material, is often incorporating some technical (and/or theoretical) limitations in the employment. the need of (i) inexpensive test, (ii) acceptable base theory, (iii) few tested samples and (v) many estimated elastic constants, is the most preferable thing to put forwards for achieving such aim. too many demands against so humble abilities!. the present paper looked for accomplishing most of these demands through the adoption of timoshenko beam theory [21] which is still found as an acceptable engineering theory. a non-destructive static deflection test (instead of the destructive tensile test) of a composite cantilever strip may be sufficed to obtain the two elastic constants associated with the principal axes of the testing sample. utilizing the familiar configuration of the samples, originally used in the tensile test, the present approach would be able to determine a maximum of six independable elastic constants from three samples preserving the same simple test set-up. the new approach had been examined, for validity assessment, by a resonant frequency test and the comparison of experimental results were made among all mentioned approaches. the present t3bt reflected very obviously its reliability and success in the achievement comparing with other techniques in literature till the time of submitting this report. 2. theoretical analysis referring to fig.1, the composite sample, under consideration, is modeled as a rectangular beam (strip) with its length, thickness and breadth kamal k.m. saify./ al-khwarizmi engineering journal ,vol.1, no. 2,pp 52-63 (2005) ٥٤ are denoted by l1,l2 and l3 respectively. the beam is supposed to be bent statically in the plane (1-2) due to an arbitrary distributing load p12 (per unit breadth) on the beam upper surface. generally, the load may be a function of location η along the major axis-1. in accordance to timoshenko beam theory the constitutivedisplacement relationships and the force-moment equilibrium conditions state that: ......(3) ).( 12 1i , .a :where ......(2) 0q , )( ......(1) em , 6 5 3 233321 12 31112 llll d dmp d dq d di d dagq == == =      += η η η η ψ η δ ψ the quantity (5/6g12), in q-expression, is the “effective” shear modulus of the strip material [20], in which the factor (5/6) refers to reissner’s shear coefficient, while g12 is simply the actual shear modulus associated with existed plane of deformation (1-2). the item e1, in m-expression, is commonly the young modulus of the cantilever material in the major direction-1. solving of the ordinary differential eq.(2) for the loading condition of concentrated force p0 at the beam tip (η=l1), and using the results into eq.(1) yields to the general expressions of the displacement components δ (the local deflection) and ψ (the section rotation) as followings: ......(4) 6 1 2 1 2 1 5 6 01 32 1 31 0 1 2 1 31 0 112 0 ccl ie p cl ie p ag p ++      −= +      −−= ηηηδ ηηψ applying the beam condition at the clamped end 0) 0( ==⇒= δψη , gives the exciplict formula for δ as varied with η, in the form: ( ) 5 3 6 112 032 1 31 0 ηηηδ ag pl ie p +−= ….(5) the two elastic constants (e1 and g12), appeared in above equation, can be calculated whenever the deflection δ is precisely measured at two locations, say the strip tip (η=l1) and the midlength (η=l1/2), resulting in: 5 3 48 5 5 6 3 112 10 31 3 10 112 10 31 3 10 ag lp ie lp ag lp ie lp m t += += δ δ ……(6) where δt and δm represent the localized deflections at the beam tip and mid-length positions respectively. eq.(6) suffices now to compute the two elastic constants of the strip from: ( ) ( ) 516 18 5 2 3 2 1 2 3 0 12 3 1 2 3 0 1 tm mt l ll p g l l l p e δδ δδ −            = −            = …(7) the benefit of above formulae, comes from that its mathematical scheme can be held correctly for general beam rotation of the coordinate axes system. it does not enforce any preferable choice of the directions (1,2,3) to be adjusted for any sides of the strip (length, thickness or breadth), i.e. eq.(7) can be utilized for any axis kamal k.m. saify./ al-khwarizmi engineering journal ,vol.1, no. 2,pp 52-63 (2005) ٥٥ rotation through (900) about its plane. this will serve to compute another set of two elastic constants (young and shear moduli) corresponding to the new axes system. in order to estimate a maximum number of these sets of moduli values, the job was devoted to conduct the deflection tests, firstly on a beam-a whose major axis coinciding with the fiber axis (i.e. parallel), secondly on a beam-b whose major axis is perpendicular to the fiber axis (i.e. normal) and thirdly on a beam-c whose major axis is at 450 with the fiber axis (i.e. inclined). these three beams are actually cut from the composite laminate as illustrated by fig.(2). each beam is then tested independently one or two times. in each time the deflection axis is altered by (900) rotation about the major axis. denoting the cartesian plane (xy) as the mid-plane of the composite laminate, where the fibers are along x-axis, and choosing z-axis to be orthogonal with (xy) through out the laminate thickness, then the complete deflection tests may be organized as followings: (i) beam-a (parallel): (1) test-1: the major axis-1 is x-axis and the deflection axis-2 is z axis, from which ex and gxz can be estimated. (2) test-2: the major axis-1 is x-axis and the deflection axis-2 is y-axis, from which ex and gxy would be then computed. (ii) beam-b (normal): (1)test-1: the major axis-1 is y-axis and the deflection axis-2 is z axis, from which ey and gyz can be estimated. (2)test-2: the major axis-1 is y-axis and the deflection axis-2 is xaxis, from which ey and gxy would be then computed. (iii) beam-c (inclined): (1) test-1: the major axis is 1-axis and the deflection axis is 2 axis, from which e1 and g12 can be evaluated. transforming the results to the actual laminate axes (xyz), then the two elastic constants (gxy and νxy) can be estimated, from this test, using (see ref.[8]): 11 4 12 11 2 4 141 12 121         +−      =         +−      += yxx xy yxxy eege eegeg ν …(8) by now, the present 3-beam samples are non-destructively tested by simple deflection tests to estimate the six elastic constants (ex, ey, gxy, νxy, gxz and gyz) of the given orthotropic material. table(1) summarizes the total five tests procedure, previously explained . note that the constants ex and ey would be averaged from the test results of beam-a and b respectively. the same thing might be done for gxy from all the three beam tests, whereas no averaging is there for gxz, gyz and νxy since they are computed one time only. 3. numerical results, discussions and comparison the ever best method to check for the validity of the present and relevant techniques to estimate the different elastic constants of an orthotropic material, is the adoption of a reference sample whose material elastic moduli had been precisely obtained and verified frequently by some reliable technique, other than these mentioned here, and see whether the present approaches retain the same elastic constants values. unfortunately, this trail failed due to the absence of such material. however, the present aim can be achieved alternatively by adoption of the same experimental and theoretical results of the different approaches. the “best” approach is that which maintaining the minimum deviations of the results throughout all cycles of the tests. it is a simple sort of “optimization” of the different four kamal k.m. saify./ al-khwarizmi engineering journal ,vol.1, no. 2,pp 52-63 (2005) ٥٦ approaches: the classical tensile test, the strength of material approach, the elasticity approach and finally the present t3bt. the present manufactured composite plate was firstly well prepared and the three strips(a,b,c) were perfectly cut along the corresponding directions as clarified by fig.2. appendices(a,b) display the main formulations to calculate the corresponding four elastic constants (ex, ey, gxy and νxy) in the light of the approaches respectively. table(2) show the entire collection of the experimental readings of the strips static deflections (using electrical resistance strain gauges) corresponded to given concentrated load at the tip end and for all strips configurations and test trails as proposed by the t3bt. table(3) presents the experimental acquired readings of the classical tensile test procedure made on the three strips and for all test trails as familiarly performed by this treatment. from these tests readings, the orthotropic elastic constants were computed and organized as shown by tables(4,5). the t3bt gives the results of six elastic modulii, whereas the classical tensile test gives the results of four elastic constants. in closing, table(5) illustrates the overall final values of the material elastic moduli as obtained by the current four approaches, mentioned before. in this table the results of the t3bt and the tensile tests are commonly averaged, from which the final standard deviations are computed easily. a little consideration into the last argument of the standard deviations in table(5) gives definitely that present t3bt estimates the accurate results in respect to the familiar tensile test approach, in addition to its ability of obtaining two further constants upon the common four ones. the mean value of these deviations, among the total six values from the t3bt, is no more than (0.053), while from the tensile test approach (with total four values) reaches to (0.108). it is very obvious that the present t3bt estimates the results two times accurate than the classical approach. henceforth, the tsai approach is more reliable in results than the strength of material approach which seems to be the worse one. the most beneficial thing regarding the present t3bt is its success in estimating the orthotropic shear moduli gxz and gyz that no other technique had achieved in similar proposition of the present work. 4. references: 1. lubin g., “handbook of composites.”, van nostrand reinhold co., 1982. 2. rosato d. and grove c., “filament winding: its development manufacture, application and design.”, 1964, j. wiley & sons inc., new york. 3. compositpro., peak composite innovations, 11372 w, parkhill dr., littleton colorado, 80127 usa, 2003. 4. fibersimtm , composite design technologies, inc., 235 wyman st., suite 100, waltham, ma 02451-1219, usa, 2003. 5. zhon x., chattopadhyay a. and thornburg r., “analysis of piezoelectric smart composites using a coupled piezoelectricmechanical model.”, j. intell. mat. sys. & strucs., vol. 11, 2000, pp. 169-179. 6. heng soo kim, aditi chattopadhyay and xu zhou, “stress analysis of smart composite structures using piezoelectric patch using thermalpeozoelectric mechanical loading.”, aiaa, vol. 52, 2002, pp. 1-13. kamal k.m. saify./ al-khwarizmi engineering journal ,vol.1, no. 2,pp 52-63 (2005) ٥٧ 7. henug soo etal, “dynamic response of smart composite shell using a coupled thermopiezoelectric-mechanical model.”, aiaa, 1-11, 2002. 8. jones r.m., ”mechanics of composites.”, mcgraw hill book co., washington d.c., 1975. 9. tsai s.w. and spinner g.s., “the determination of the moduli of anistropic plates.”, asme transc., j. appl. mechs., vol. 30, 1963, pp. 467-468. 10. halpin j.c. and tsai s.w., “effects of environmental factors on composite materials.”, j. composite mat., vol. 1, no. 1, 1969, pp. 4-10. 11. joens e., “on the determination of the dynamic modulus of uniform bar under torsional vibration.”, j. modern physics (west germany), vol. 11, 1931, pp. 649-678. 12. pickett g., “equations for computing elastic constants from flexural and torsional frequencies of vibration of prisms and cylinders.”, procc. am. soci. testing mats., vol. 45, 1954, pp. 846-865. 13. hasselmen d.p., “tables for the computation of the shear modulus and young modulus of elasticity from the resonant frequencies of rectangular prisms.”, the carborundum co., new york, niagara falls, 1961. 14. spinner s. and tefft w., “a method for determining mechanical resonance frequencies and for calculating elastic moduli from these frequencies.”, procc. am. soci. testing mats., vol. 61, 1961, pp. 1221-1238. 15. rubben a. and scharr g., “method of determination the complete three dimensional elastic compliance matrix of composite material.”, j. comp. structs., vol. 27, 1987, pp. 760-773. 16. deobald l.r. and gibson r.f., “determination of the elastic constants of orthotropic plates by a modal analysis/raylieghritz technique.”, j. soun. vibr., vol. 124, no. 2, 1988, pp. 269283. 17. dossing o., “structural testing. part-ii: modal analysis and simulation.”,bruel & kjaer publishings, 1988, pp. 26-27. 18. saify k.m. and al-temimi a.n., “a new proposal to compute the dynamic elastic moduli and timoshenko shear coefficient of isotropic prismatic bars.”, procc. 4th sci. engg. conf., univ. baghdad, 1997, 2me33. 19. saify k.m., “elasto-static &dynamic investigation into composite plates & shells with new approaches for estimation of the elastic moduli.”, ph.d. thesis, univ. baghdad, 2000. 20. levinson m., “a new rectangular beam theory.”, j. soun. vibr., vol. 74, no. 1, 1981, pp. 81-87. 21. timoshenko s., “on the correction for shear of the differential equation of transverse vibration of prismatic bars.”, phil. magz., vol. 41, series 6, 1921, pp. 125-127. kamal k.m. saify./ al-khwarizmi engineering journal ,vol.1, no. 2,pp 52-63 (2005) ٥٨ given the physical & mechanical properties of the fiber (e-glass) and matrix (epoxy) constituents of the composite material (the present fabricated laminate) as listed below: the apparent elastic constants and mass density of the orthotropic laminate may be computed as followings (see ref.[8,9] where deep details on the chemical compositions are discussed): 1 1 mmff mmffxy m m f f xy m m f f y mmffx vv vv g v g v g e v e v e eveve ρρρ ννν += += += += += ……(a -1) with the notations (f, m) refer to the fiber and matrix constituents respectively appendix(b): the elasticity approach. referring to the theoretical concepts of tsai & halpin in the micromechanics of composite material of two constituents, discussed earliarly, the four apparent elastic constants were driven in the form of: { } { } { } )1(g , )1( )1(e , )( 65xy43 210y kckckckc kckckveveke xy ffmmx +−=+−= +−=+= ν ……(b-1) where c and k are the effective “fudge” factor and the misalignment factor respectively. their magnitudes are actually taken to be in the range (0.85-1.00) for the first factor and (0.0-0.4) for the second one, as proposed by the authors above. the six k’s coefficients in eq.(b-1) are computed from: specification fiber (e-glass), vf=45% matrix (epoxy) vm=55% young modulus 72.40gpa 3.40gpa shear modulus 29.67gpa 1.27gpa poisson’s ratio 0.220 0.34 mass density 2.54x10-6 kg/mm3 1.22x10-6kg/mm3 appendixes appendix(a): strength of material approach. kamal k.m. saify./ al-khwarizmi engineering journal ,vol.1, no. 2,pp 52-63 (2005) ٥٩ )()( )()( )(2 )(2 )()2( )2()2( )()2( )2()2( )(2)2( )()2( )(2)2( )()2( )1(2 6 5 4 3 2 1 0 mmfmf mmfmf f mmfm mmff m mfmffmf fmmfmmffmf mmfmmmf mmfmmfmmff mfmfm mmfmfmf mmfmm mmfmmmf mmff vgggg vgggggk vggg vggggk vkkggkk vgkkvgkkk vkkggkk vgkkvgkkk vkkgk vkkggkkk vkkgk vkkggkkk vvk −++ −−+ = ++ −− = −−+ +++ = −−+ +−+ = −−+ −−+ = −++ +−+ = −−= νν νν νν ……(b-2) with all other notations are as being defined in appendix(a) kamal k.m. saify./ al-khwarizmi engineering journal ,vol.1, no. 2,pp 52-63 (2005) ٦٠ table(2). the present t3bt readings of the composite cantilever strips under the proposed static deflection tests.(refer to fig.(2)). scheme of test test-1 test-2 reading items p0 (kg) δm (mm) δt (mm) p0 (kg) δm (mm) δt (mm) strip-a trial(1) 1.00 1.5875 5.0763 50.00 0.4571 1.2955 trial(2) 1.50 2.3526 7.5231 75.00 0.6950 1.9544 trial(3) 2.00 3.1274 10.0007 90.00 0.8338 2.3428 strip-b trial(1) 0.50 2.1473 6.8676 50.00 0.9374 2.8374 trial(2) 0.75 3.0527 9.7637 75.00 1.3575 4.0835 trial(3) 1.00 4.1033 13.1237 90.00 1.6415 4.9385 strip-c trial(1) 25.0 0.8230 2.1363 trial(2) 35.0 1.1516 2.9673 trial(3) 45.0 1.4879 3.8349 table(3). the present simple tensile test readings of the composite cantilever strips. reading items p0 (kg) ∆l* (mm) ∆b** (mm) strip-a trial(1) 300.0 0.800 0.098 trial(2) 350.0 0.964 0.078 trial(3) 400.0 1.096 0.072 strip-b trial(1) 300.0 1.943 0.089 trial(2) 350.0 2.094 0.078 trial(3) 400.0 2.430 0.072 strip-c trial(1) 300.0 0.710 trial(2) 350.0 1.312 trial(3) 400.0 1.571 (*) longitudinal elongation of the tested strip. (**) lateral contraction of the strip. table(4). computations of the elastic constants of the composite strip from two present theoretical/experimental approaches. approach the estimated elastic moduli of the present orthotropic material ex (gpa) ey (gpa) gxy (gpa) νxy gxz (gpa) gyz (gpa) t3bt (*) trial(1) 6.613 2.361 1.985 0.221 1.779 0.879 trial(2) 6.693 2.491 1.865 0.371 1.869 0.949 trial(3) 6.713 2.471 1.855 0.371 1.899 0.929 tensile test (**) trial(1) 7.380 3.030 2.141 0.444 trial(2) 7.120 3.280 2.441 0.324 trial(3) 7.160 3.230 2.351 0.264 (*) refer to eqs.(5,6,7). (**) ei=p0.li/(lj.lk).∆li, νij=∆lj.li/lj. ∆li (i,j,k=x,y,z or 1,2,3) with the help of eq.(7). kamal k.m. saify./ al-khwarizmi engineering journal ,vol.1, no. 2,pp 52-63 (2005) ٦١ table(5). comparison of the estimated results of the orthotropic elastic moduli of the present composite material according to variety of current approaches. approach the main elastic constants ex (gpa) ey (gpa) gxy (gpa) νxy gxz (gpa) gyz (gpa) t3bt average 6.673 2.441 1.905 0.321 1.849 0.919 σ(*) 0.043 0.057 0.064 0.071 0.051 0.029 tensile test average 7.220 3.180 2.311 0.344 σ(*) 0.123 0.108 0.126 0.075 strength of material($) 7.081 4.003 1.502 0.294 elasticity($$) 6.727 2.340 1.822 0.302 (*) standard deviation ( ) 3 3 1 2∑ = − = i iaveragevalue ($) refer to appendix(a). ($$) refer to appendix(b). kamal k.m. saify./ al-khwarizmi engineering journal ,vol.1, no. 2,pp 52-63 (2005) ٦٢ figure (2) figure (1) kamal k.m. saify./ al-khwarizmi engineering journal ,vol.1, no. 2,pp 52-63 (2005) ٦٣ تقنية توموشينكو ثالثية العتبة لتقدير معامل المرونة الرئيسي للمواد )المتجانسة ثالثية البعد( جويج محسن جبر.د عدنان ناجي جميل التميمي.د كمال مصطفى كمال محمود سيفي.د كلیة الھندسة /قسم المیكانیك كلیة الھندسة /قسم المیكانیك بغداد-الكلية التقنية/قسم القوالب والعدد النهرينجامعة جامعة بغداد :ةخالصال طريقة مطورة جديدة ، لحساب ثوابت المرونة الستة والضرورية لتحليل التصرف الميكانيكي والداينماكي دة الصفات الهندسية، قد قدمت في هذه الورقة للمرة األولى من نوعها للشرائح المركبة المتجانسة متعام للقضبان المركبة الناتئة " تيموشنكو"اعتمدت الطريقة على نظرية . في األساس النظري وإجراءات العمل يتطرق الجانب العملي الى استخدام ثالث شرائح مركبة من المادة على طول المحاور . والمنحنية سكونيا سية الثالث وإيجاد االزاحات السكونية المناظرة لكل شريحة وبمستويين متعامدين من منظومة المحاور األسا تم إجراء خمسة محاوالت تجريبية بواقع اختبارين لكل محاولة وحساب معامالت . األساسية للتركيب إقرار الموثوقية للنتائج لغرض . ونظرية الميكانيك الدقيق للمواد المركبة" تيموشنكو"الصالبة وفق معادالت المختلفة، تم إجراء ثالث اختبارات كالسيكية للشد لجميع نماذج التجربة ومقارنة القراءات النهائية للصالبة لقد أثبتت الطريقة المقدمة كفاءتها وصحة نتائجها بإعطائها أقل االنحرافات العددية . في االتجاهات الرئيسية .متازت ببساطة ودقة الشكل الرياضي للحلمقارنةً بالطرق السابقة، كما ا <4d6963726f736f667420576f7264202d20d2edcf20e6c7cdd3c7e420e6dfc7d9e332302d203331> al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 14, no. 3, september, (2018) p.p. 2031 experimental and simulation investigations of micro flexible deep drawing using floating ring technique zaid h. mahmood* ihsan k. irthiea** kadum a. abed*** *,**,***department of mechanical engineering/ college of engineering/ university of anbar/ anbar/ iraq *email: zaid_eng88@yahoo.com **email: ih77san@yahoo.co.uk (received 30 august 2017; accepted 26 december 2018) https://doi.org/10.22153/kej.2018.12.007 abstract micro metal forming has an application potential in different industrial fields. flexible tool-assisted sheet metal forming at micro scale is among the forming techniques that have increasingly attracted wide attention of researchers. this forming process is a suitable technique for producing micro components because of its inexpensive process, high quality products and relatively high production rate. this study presents a novel micro deep drawing technique through using floating ring as an assistant die with flexible pad as a main die. the floating ring designed with specified geometry is located between the process workpiece and the rubber pad. the function of the floating ring in this work is to produce ss304 micro cups with profile radius precision as required as possible. the finite element simulations are accomplished using the commercial code abaqus/standard. in order to verify the simulation models, micro deep drawing experiments are carried out using a special set up developed specifically to meet the requirements of the simulations. the results revealed that the proposed technique is feasible to be adopted for producing micro cups with remarkable application capability in miniaturization technology. keywords: flexible tool, micro deep drawing, finite element simulation, floating ring. 1. introduction the increasing demand on micro parts utilized in various industrial fields, including electronics and micro-medical devices get the manufacturers into a competitive situation [1]. therefore, using advanced manufacturing processes and innovative techniques has significantly become urgent need for technology advancement [2]. recently, sheet metal forming using flexible tools is one of the forming techniques that attract great attention of many researchers. flexible tool-assisted sheet metal forming can be characterized by its feasibility for prototyping processes, simplicity and versatility. in comparison to conventional deep drawing, flexible tool-assisted deep drawing has many other advantages such as better surface quality, better dimension accuracy, capability for complex shaped parts and lower production cost [3, 4]. f. quadrini et al. [5] studied the effect of die material and its geometry on forming processes of aluminum sheet metal with thickness 150µm. the dies used were rigid, silicone rubber, styrene butadiene rubber and polyamide 66. the results showed that using semi-rigid die contribute in production improvement in terms of forming force reduction and die durability. flexible pad laser shock forming (fplsf) process was presented by nagarajan b. et al. [6] to investigate the influence of flexible pad material and its thickness, on the deformation characteristics of different metal foils. it was observed that using rubber material with higher hardness resulted in a reduction in crater depth, foil thickness and the hardness of the crater surfaces. however, increasing the flexible pad thickness resulted in an increase in crater depth, thinning but a reduction in surface hardness. y. liu et al. [7] used rigid zaid h. mahmood al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 2031 (2018) 21 dies with two different designs, concave and convex, with flexible pad to produce micro channels. the results showed that the concave design of die more suitable to fabricate micro channels and however thickness reduction in convex design was decreased with increasing aspect ratio value. c. jin et al. [8] studied the effect of rubber pad properties, speed and pressure of punch on forming behaviour of different sheet metals, stainless steel 304, aluminum 1050 and titanium. the results demonstrated that the depth of the micro channels can be increased by using softer rubber or increasing any of rubber thickness, punch speed and punch pressure. i. irthiea et al. [3] proposed a new technique for forming micro cups from stainless steel 304 sheets with different initial thicknesses using flexible pad. many process parameters were studied in this work such as anisotropy of ss 304 material, initial gap, friction conditions at various contact interfaces and initial sheet thickness. this study proved that the interaction among the adopted parameters result in producing successful micro cups with high aspect ratio and high quality. wang at el. [9] introduced a novel laser dynamic flexible forming technique through experiments and numerical simulations. the results showed that increasing the thickness of the soft punch leads the depth of the formed sheet to decrease. also, as the pulse energy increases the deformation depth increase as well. the deep drawability of ultrafine grained copper sheet of 0.4mm thickness was studied by ma et al. [10] using the method known equal channel angular pressing (ecap) for various ultrafine grained microstructure. it was obtained minimum limit drawing ratio with one ecap pass and increasing the number of passing caused a slight increase in the limit drawing ratio. the same observation was pointed by lapovok et al. [11] in a study achieved on ultrafine grained aluminum sheet. this work presents a novel flexible toolassisted micro deep drawing process (ftamdd) of stainless steel 304 foil using polyurethane rubber ,55 shore a hardness, as forming die with floating ring technique. the circular blanks used as process workpieces were cut from ss 304 foil of 100μ with 10mm diameter. the novelty point of this study is to use a floating ring part, as assistant die, in cooperating with flexible die to produce micro cups with high quality in terms of wall thickness and dimensions. the finite element simulations were built using the commercial code abaqus/standard. serious of micro deep drawing experiments were implemented to validate the fe models. the main purpose of this work is to evaluate the feasibility of the proposed technique in miniaturization technology. there was observed a good correlation between the simulation and experimental results in terms of final cup shape, thickness distribution, punch force and maximum reduction in thickness. 2. proposed methodology (innovative technique) in the proposed technique, the forming process is divided into three main steps to obtain complete micro cups. in the first step, the forming depth will be equal to the floating ring thickness where the lower face of workpiece will be just get into direct contact with the rubber pad surface. in the second step, the solid punch will keep pushing the shallow-formed blank into the flexible die, generating a hydrostatic pressure in the rubber material. this action will basically result in forming both the sheet blank and rubber die simultaneously. fig. 1. forming system of the proposed technique. hereafter, the rubber material will push up the floating ring and consequently the blank as well towards the blank holder against the holding spring through the initial gap allocated between the adjustment ring and the blank holder. at the moment when the adjustment ring touches the zaid h. mahmood al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 2031 (2018) 22 blank holder plate the third step begins in which the forming processing process is terminated under the effect of the punch force and the hydrostatic rubber pressure. 3. characterization of material behaviors 3.1 preparation of tensile test specimens chromium-nickel stainless steel 304 foils (ss 304), which its chemical composition is illustrated in table 1, with initial thickness of 100μm are used in this study for process workpieces. the many advantages of stainless steel 304 such as anticorrosion and lifetime of products make the fabrication and industrial applications of ss 304 sheets remarkably increases [3]. table 1, chemical composition of stainless steel 304 sheet metal. the effect of the anisotropic behaviour (due to the rolling operation) of the ss 304 foil are evaluated here through cutting dogbone-shaped specimens along rolling, diagonal (45°) and transverse directions. the dimensions for the dogbone specimens are obtained from the astm e8 [12] standard as shown in figure 2a. however, the very thin stainless steel sheets are very difficult to cut directly using traditional methods and tools as they may fold through handling and cutting or rough cut edges may be obtained. to solve this problem, the stainless steel sheet is clamed between two perspex plates of 1cm thickness and the cutting operation is then carried out. high attention is paid for that area near the cutting edge where number of fasteners are specifically fixed at this area to ensure additional support to prevent relative shaking as explained in figure 2b. the specimens of ss 304 are cut by using cnc cutter machine from c-tek company with spindle velocity equal to 2500 rpm and cutter tool with 2mm diameter, as shown in figure 2c. (a) (b) (c) fig. 2. (a) dogbone sample (b) drilling system (c) cutting process of dogbone samples. 3.2 tensile test of ss 304 material the tensile tests of ss 304 dogbone-shaped specimens are carried out using the universal tensile machine supported by the laryee company to the center of nano technology / university of technology. the load capacity of the laryee machine is 100kn with accuracy +/ 0.5% as shown in figure 3. the contact conditions between grips surface and specimen surface has a crucial influence on testing results, especially with thin metals. in order to avoid folding the dogbone-shaped specimens of the tensile test, often at the profile radius, it was observed that the friction force at the interface between the grips and specimen should be increased. this action will prevent any probable sliding of the specimen with the surfaces of gripers. owing to do that, pieces of sand papers were inserted at the specimen/gripers interfaces. cr mn ni c fe 17-20% <2% 8-11% <800 balance zaid h. mahmood al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 2031 (2018) 23 the tensile test achieved at velocity of 0.2mm/s. through test stroke and at 20% of total longitudinal strain, a picture is taken for the loaded specimen utilizing a digital camera and this picture is then analyzed by a special software for image processing to evaluate the lateral strain. fig. 3. (a) laryee machine (b) dogbone sample before the test (c) dogbone sample after the test. the purpose of this action is to evaluate the lateral strain at this point. figures 4 and 5 present the engineering and true stress-strain relationships obtained from the tensile tests for the stainless steel 304 foil with 100μm thickness adopted for the forming blanks in this work. the mechanical properties that obtained from tensile test are recorded in table 2. table 2, mechanical properties of ss 304 foil. fig. 4. engineering stress-strain for ss304. fig. 5. true stress-strain for ss304. 4. material models in fea simulation 4.1 anisotropy of stainless steel foil the commercial code abaqus/standard software was employed in this study to develop fe simulations for the flexible tool-assisted micro deep drawing. to characterize the deformation behaviour of ss 304 foils, an elastic-plastic model was adopted. to build this model, 8300 elements with mesh type of 8-node linear brick, reduced integration and hourglass control (c3d8r) as shown in figure 7a. the boundary conditions of blank are at zaxis direction as xsymm (u1=ur2=ur3=0) while at x-axis direction as zsymm (u3=ur1=ur2=0). the plastic anisotropy is introduced by using hill's criterion. f�σ�=� f�σ��-σ���2+g�σ��-σ���2+ h�σ��-σ���2+2lσ��� +2mσ��� +2nσ₁₂² …(1) the material constants f, g, h, l, m and n are obtained from tensile tests in different orientations and σij refers the stress components [13]. these constants are defined as: f � 12� 1r��� � 1r��� � 1r��� � … �2� g � 12� 1r��� � 1r��� � 1r��� � … �3� h � 12� 1r��� � 1r��� � 1r��� � … �4� l � 32r₂₃² m � 32r₁₃² n � 32r₁₂² … �5� the factors r11, r22, r33, r12, r13 and r23 are anisotropic yield stress ratios. due to the stress situation in sheet metal forming processes are characterized by plane stress conditions therefore thickness (mm) e (gpa) σo (mpa) σult (mpa) εult % k (mpa) n 0.1 0° 194 291 540 19.51 1213.10.3708 45° 149 324 625 24.86 1298.90.3469 90° 181 310 622 23.20 1444.70.4103 zaid h. mahmood al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 2031 (2018) 24 four anisotropic ratios are considered in this work which are r11, r22, r33 and r12 [14]. in abaqus software, these factors are expresses using lankford factors as r0, r45 and r90 as following equations [15]: r22=�r90�rₒ+1� rₒ�r!"+1� r33=�r90�rₒ+1� rₒ+r!" r�� � � 3r₉ₒ�rₒ � 1��2r₄₅ � 1��rₒ � r₉ₒ� … �6� where r0, r45 and r90 are width strain to thickness strain ratios of the work-piece material at the rolling, diagonal and transverse directions, respectively. the values of (r) and (r) of ss 304 sheets employed in the current work are calculated using the above equations, as shown in table 3. table 3, plastic strain ratios and anisotropic yield stress ratios. fig. 7. (a) fe model of ss 304 blank (b) fe model of flexible pad. 4.2 hyper-elastic model for rubber pad material to describe the behaviour of the polyurethane rubber used for the flexible die, the known mooney-rivlin hyperelastic model is adopted in the fe model. it is known that polyurethane rubber is characterized by a nonlinear stress– strain relation for large deformation, as well as it is nearly incompressible. the strain energy form of mooney–rivlin is: w=c10(i1-3)+c01(i2-3)+(j1-1)/d1 …(7) where w is the strain energy per unit of volume, i1 and i2 are the strain invariants, j is volume change. c10 and c01 describe hyperelastic rubber deformation, and d1 indicates the material compressibility [16]. the deformation behavior of rubber material was described by using hyperelastic model. this part has 13806 elements with mesh type 8-node linear brick, hybrid, constant pressure, reduced integration and hourglass control (c3d8rh). the mechanical properties of the polyurethane rubber 55 shore a hardness are presented in table 4 [17]. table 4, mechanical properties of polyurethane rubber materials. hardness shore a m–r constant c10 (mpa) m–r constant c01 (mpa) poisson’s ratio (v) 55 0.382 0.096 0.4999 the process geometry dimensions adopted in this study are listed in table 5. the coefficients of friction adopted at the different contact interfaces in the finite element models are presented in table 6. table 5, geometrical parameters of flexible micro deep drawing model. parameters value(mm) blank diameter blank thickness punch diameter radius of punch corner height of rubber pad diameter of rubber pad thickness of flat floating ring diameter of floating ring radius of inner corner of floating ring 10 0.1 4 0.8 10 12 1 13 0.75 table 6, coefficients of friction adopted at different interfaces. interface coefficient of friction blankholder / blank floating ring / blank rubber pad / blank punch / blank floating ring / rubber pad adjustment ring / blankholder 0.1 0.05 0.1 0.25 0.05 0.05 rolling direction eng. length strain eng. width strain thickness strain plastic strain (r) 0° 0.2 -0.40 0.6931472 0.73696559 45° 0.2 -0.69 1.3535045 0.86529668 90° 0.2 -0.44 0.7621401 0.76077683 r11 r22 r33 r12 1 1.00912 0.93929 0.98455 zaid h. mahmood al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 2031 (2018) 25 5. experimental set up to conduct micro deep drawing experiments under that conditions a special device is required to be manufactured with accuracy level meets the operation requirements. the device consists from three main groups of parts; the first group includes the movable parts and the second includes fixed parts, then the floating part as shown in figure 8. the movable group involves in turn two subgroups, the first one consists of rigid punch and punch plate, while the second one consists of middle plate, blankholder, blankholder house, adjustment ring, three adjustment studs and holding spring. the rigid punch has a threated head at which it is attached to the punch plate and both of them connect to the compression machine grip through a span. the blank holder house and middle plate are connected together using three studs. the other function of these three studs is to adjust the distance between blank holder and middle plate from a side and the distance between the blankholder house and the adjustment ring from another side. the last distance actually represents the initial gap, mentioned in figure 1, through which the blankholder move up just against the holding spring force. the second main group, i.e fixed parts, consists of the heavy base of the device, three guides, rubber pad house and the upper ring. the rubber pad material that manufactured by par group ltd. in the uk with grade 55 shore a has geometrical properties as the height equal to 10mm and 12mm as diameter. the difference between the height of rubber container and rubber pad equal to 5mm, through this space the floating ring will be placed and the remaining space is for the blankholder. the last component of the device developed for the current experiments is the floating ring which represents the novel point of this research. the dimensions of flat floating ring are the thickness equal to 1mm and the outer, inner diameters equal to 12mm and 4.24mm, respectively and the inner hole has edge curvature equal to 0.75mm. 6. experiment procedure in micro sheet metal forming, the blanking operation has high importance as it is represented a crucial action on which the success of micro forming process significantly depends. to carry out blanking process, a set of punch /die tool with specific dimensions is utilized. the most important parameter in any sheet blanking operation is the clearance between the punch and die. in order for high quality cutting process, a clearance of about 12–24 % of the initial foil thickness should be adopted for the punch/die set [4]. thus, the blanking tools used in the current work were designed and manufactured with clearance of 20% which means approximately 20μm (see figure 9). fig. 8. flexible too-assisted micro deep drawing device. fig. 9. (a) blanking tools (b) blanks of ss304 with 10mm diameter. the flexible micro forming experiments were implemented using laryee machine which has the load capacity equal to 100kn with accuracy +/0.5%. to start the experimental procedure, firstly an initial gap is adopted very carefully and accurately between the adjustment ring and the blankholder house. thereafter, the outer studs are tightened on the upper plate and let the punch plate free at this step. through this procedure will permit more support to the device during the zaid h. mahmood al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 2031 (2018) 26 forming process. the next step is to insert the floating ring onto the rubber pad die and then insert the blank over the floating ring and ensuring from it’s in the correct position. fig. 10. components of device. now, the device ready to setup on the universal machine and attach the upper span to the machine grips. the forming was done with 1mm/s as forming speed until reaching the specified depth. figure 10 shows the components utilized in the micro forming operation. 7. results and discussions the crucial parameter of evaluating the product quality is the thickness distribution along the entire cup wall. therefore, a homogenous thickness distribution of the product represents indication of good quality. therefore, a special technique required to obtain good cutting process. in this study, we used the epoxy liquid which mixed carefully with its hardener. thereafter, the solid system is extracted from the die. now, the cup is ready for cutting process. the cutting process was done by using mechanical cutter machine with blade cutter thickness equal to 0.1mm. to obtain a good status of edge of cup, the cut face is polished using very fine sand paper. figure 11 shows the section of epoxy and metallic cup cut along the rolling direction. after that, the thickness distributed along wall cup was evaluated by using microscope machine to determine the real value the thickness at every point of wall cup. fig. 11. section of epoxy material and metallic cup. 7.1 thickness distribution this section includes the results that obtained from the experiments of micro deep drawing and validate these results with that obtained by fe simulation under the corresponding conditions. in this study, there are two parameters studied for one case such as thickness distribution and loaddisplacement relation. to study these parameters, the conditions that adopted in the experiments procedure were as following: punch diameter was 4mm with head radius 0.8mm, rubber pad diameter was 12mm with height 10mm, initial blank thickness 0.1mm with 10mm as diameter, floating ring thickness was 1mm with shoulder radius 0.75mm and forming velocity was 1mm/s. among these parameters the initial gap that adopted has a crucial effect on the forming process. the unsuitable gap distance leads to failure the product as shown in fe simulations. figure 13 shows the cups obtained from micro deep drawing experiments. firstly the fracture part, as mentioned above the gap value has a crucial effect so that at this case due to gap distance very small, the fracture occurred. this type of failure was verified through fe simulation for the same reason in figure 12. zaid h. mahmood al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 2031 (2018) 27 fig. 12. comparison the failure cups through simulation and experiment drawing. on the other hand, micro cups with wrinkling was obtained when the adopted gap is greater than the optimum one, this action allow for the blank to deform freely for longer time through the deeper gap without supporting force. the folds appear firstly at the flange portion and then move along to cup-side wall gradually with the forming stroke. also, this type of failure was verified by fe simulation as shown in figure 12. afterward, great efforts were done to adjust the appropriate gap which finally found to be 0.2mm for the conditions taken into account to produce successful cups as shown in figure 13. the figures 14 and 15 presented a comparison of thickness distributions of wall cup for simulation and experimental. the results showed well match of the results that obtained by simulation and experimental along rolling and transverse directions. this indicate to the results that obtained by experimental agree with the predictions of simulation results. the maximum thinning occur at profile radius region for both simulation and experiment along rolling and transverse directions. after that, the tendency of thinning disappeared at side wall region and the thickness of wall increased gradually to be thickening at the upper part of side wall. in general, the thickening trend continued until reaching the maximum value at the ending part of shoulder radius region. then, the thickening decreased along flange portion. for more realization, figure 16 present percentage of maximum thinning that occur for both simulation and experimental results along rolling and transverse directions. fig. 13. physical micro formed cups. fig. 14. thickness distributions of wall cup at rolling direction. the maximum thinning was 17% along rolling direction of physical cup. while, the simulation result revealed decreasing the tendency of thinning to be 14%. on other side, the transverse direction don’t display a significant thinning variation between the simulation and experimental results. where the maximum thinning was 13.44% for simulated cup while 13% for physical cup. zaid h. mahmood al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 2031 (2018) 28 fig. 15. thickness distributions of wall cup transverse direction. fig. 16. maximum thickness reduction. 7.2 load-displacement relationship figure 17 present the relation between load and displacement of punch for both simulation and experimental of cup drawing. in general, the curves showed the same trend during the forming process until reaching the maximum value of load. firstly, the experiment curve showed increasing dramatically due to the forming tools are initially in contact with them which lead to make the force required higher than that obtained by simulation. although, the experiment curve is higher than that obtained by fe simulation. but, the last step revealed the experiment load decreased to be less than that predicted by fe simulation. this effect may be due to the rubber container diameter is relatively greater than as adopted in simulation model that lead to expanding the rubber in radial direction. fig. 17. comparison punch load-displacement relation for both simulation and experiment. the difference between these curves due to the experimental difficulty to determining the coefficient of friction between the interfaces of forming tools. also, the device of experiment drawing consist of different parts have a contact between them. all these parameters may be lead to the experiment load higher than that obtained by simulation drawing. the maximum load that obtained by simulation was 412.35n while the experiment load was 396.47n. on other side, the novel proposed technique revealed the feasibility to produce micro cups with aspect ratio higher than unity through one stroke of forming. the results that obtained by simulation process to produce cups with aspect ratio 1.25 are validated by experiment process. the same conditions that adopted in simulation process are used in the process of experiment. the physical cup showed a good correlation with that predicted by simulation in term of geometrical profile. also, it can denote that there is a good matching between the two parts in term of the effect of anisotropic behavior of ss304 sheet metal. figure 18 presents a comparison between the simulation and physical parts. fig. 18. comparison between physical and simulated cups that have aspect ratio 1.25. zaid h. mahmood al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 2031 (2018) 29 8. conclusion the current study presents a novel technique for micro deep drawing of stainless steel 304 cups through using a floating ring concept with the technology of flexible tool. an experiments and fe simulations were achieved to validate the feasibility of the proposed technique. the forming procedure starts with adopting a particular initial gap the blank holder and the adjustment ring. this gap allows for all of blank, blankholder and floating ring to move up just against the force of holding spring under the effect of the hydrostatic pressure excited in the rubber material-die. basically, the main function of the floating ring part is to define the dimension of the required product at the profile radius as well as to work as an assistant die allowing for the blank to form initially without rubber pad-excited hydrostatic pressure for a partial period of the whole forming stroke. the important finding here is that the current technique exhibits a clear role in reducing the influence of the anisotropic behaviour of ss 304 sheet on the thickness distribution of formed cups. it was observed that using the technique of floating ring results in reducing the maximum external load required to complete the forming stroke compared with the results obtained by i. irthiea. another finding is that a good correlation between the simulations and the experimental results was obtained. this study proved the capability of the new technique to be adopted for prototyping micro forming processes. moreover, the study revealed the feasibility of the proposed technique for producing micro cups with remarkable application flexibility in miniaturization technology as micro cups with relatively high aspect ratio of 1 and 1.25 through just a single micro forming stage. 9. references [1] y. m. huang & y. s. wu & j. y. huang, “the influence of ultrasonic vibrationassisted micro-deep drawing process”, international journal of advanced manufacture technology, (2014) 71:1455– 1461. [2] masoomeh salahshoor & abdolhamid gorji and mohammad bakhshijooybari, “the study of forming concave-bottom cylindrical parts in hydroforming process”, international journal of advanced manufacture technology, (2015) 79:1139–1151. [3] ihsan irthiea, graham green, safa hashim and abdulbast kriama, “experimental and numerical investigation on micro deep drawing process of stainless steel 304 foil using flexible tools”, international journal of machine tools & manufacture, (2014) 76:21–33. [4] ihsan k. irthiea and graham green, “evaluation of micro deep drawing technique using soft die-simulation and experiments”, international journal of advanced manufacture technology, (2017) 89:2363– 2374. [5] quadrini f, santo l, anna e (2010) flexible forming of thin aluminum alloy sheets. int j mod manuf technol, ii: 79–84. [6] balasubramanian nagarajan, sylvie castagne, zhongke wang, h.y. zheng and kartikeyan nadarajan, “influence of plastic deformation in flexible pad laser shock forming – experimental and numerical analysis”, international journal of material forming, 1-15. [7] liu y, hua l, lan j, wei x, “studies of the deformation styles of the rubber-pad forming process used for manufacturing metallic bipolar plates”, j power sources, (2010) 195:8177–8184. [8] c. kyu, m. geun, and c. gil, “effect of rubber forming process parameters on micropatterning of thin metallic plates,” procedia eng., vol. 81, pp. 1439–1444, 2014. [9] wang x, du d, zhang h, shen z, liu h, zhou j, liu h, hu y, guc, “investigation of microscale laser dynamic flexible forming process-simulation and experiments”, international journal of machine tools & manufacture, (2013) 67:8–17. [10] x. ma, r. lapovok, c. gu, a. molotnikov, y. estrin, e. v. pereloma, c. h. j. davies and p. d. hodgson, "deep drawing behaviour of ultrafine grained copper: modelling and experiment", journal of material sience, vol. 44, pp. 3807-3812, 2009. [11] r. lapovok, i. timokhina, p. w. j. mckenzie and r. o’donnell, "processing and properties of ultrafine-grain aluminium alloy 6111 sheet", journal of materials processing technology, vol. 200, pp. 441450, 2008. [12] american society for testing and materials astm, “standard test methods for tension testing of metallic materials,” am. assoc. state, pp. 1–27, 2010. zaid h. mahmood al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 2031 (2018) 30 [13] le port a, toussaint f and arrieux r, “finite element study and sensitive analysis of the deep drawing formability of commercially pure titanium”. international journal of material forming, (2009) 2:121– 129. [14] d.v. hai, s. itoh, t. sakai, s. kamado, y. kojima,”experimentally and numerical study on deep drawing process for magnesium alloy sheet at elevated temperatures”, materials transactions, (2008) 49:1101–1106. [15] ihsan khalaf irthiea, “process analysis and design in micro deep drawing utilizing a flexible die,” university of glasgow, 2014. [16] l. crocker and b. duncan, “measurement methods for obtaining volumetric coefficients for hyperelastic modelling of flexible adhesives”, performance of adhesive joints program, project pajex2 flexible adhesives, pajex2 report no 3. [17] linfa peng, peng hu, xinmin lai, deqing mei, jun ni, “investigation of micro/ meso sheet soft punch stamping process— simulation and experiments”, materials &design, (2009) 30:783–790. )2018( 20-31، صفحة 3د، العد14دجلة الخوارزمي الهندسية المجلمزيد حمد محمود 31 الطافي تحقيق عملي ومحاكاة لعملية سحب عميق مايكروية بأدوات مرنة بأستخدام تقنية الحلق ***كاظم احمد عبد** إحسان خلف رثيع* حمد محمودزيد العراقاالنبار/ /رجامعة االنباقسم الهندسة الميكانيكية/ كلية الهندسة/ zaid_eng88@yahoo.com :البريد االلكتروني** ih77san@yahoo.co.uk :البريد االلكتروني** الخالصة بأستخدام أدوات مرنة عند مستوى ابعاد عملية تشكيل الصفائح المعدنية التشكيل المايكروي للمعادن يملك قابلية تطبيق هى مجاالت صناعية مختلفة. ً تقنيات التشكيل التي تملك جذبمن بين دمايكروية يع الهتمام الباحثين. عملية التشكيل هذه مناسبة النتاج مركبات مايكروية كونها عملية رخيصة، اً متزايد ا ً قالب بوصفهسحب عميق مايكروية مبتكرة من خالل استخدام حلق طافٍ . هذه الدراسة تقدم تقنيةتؤدي الى منتجات عالي الجودة و نسبيا معدل انتاج عالٍ ا العينة والوسادة المرنة. وظيفة وفق هيئة هندسية معينة يوضع بين على قالب تشكيل رئيس. الحلق الطافي المصممبوصفها مرنة وسادة الى جانب اَ مساعد منتجات مايكروية على شكل كؤس مصنىوعة من فوالذ مقاوم للصدا بأبعاد عالية الدقة. مودبالت العناصر المحددة الحلق الطافي في هذا العمل هي انتاج ليالقي متطلبات انجزت باستخدام برنامج . الثبات صحة النتائج النظرية مجموعة تجارب سحب عميق أجريت بأستخدام جهاز صمم وصنع خصيصا أن التقنية المقترحة في هذه الدراسة هي ذات جدوى النتاج منتجات مايكروية التي تملك امكانية تطبيق عالية في التكنولوجية أثيتت بالموديل النظري. النتائج صغيرة االبعاد. free-vibr-1 dr: hussain a.dawood /al-khwarizmi engineering journal ,vol.1, no. 2,pp 86-102 (2005) ٨٦ al-khwarizmi engineering journal al-khwarizmi engineering journal, vol.1,no.2,pp 86-102, (2005) free vibration analysis for dynamic stiffness degradation of cracked cantilever plate dr: hussain a.dawood oday. i. abdullah mechanical engineering department nuclear engineering. department. college of engineering/ university of baghdad college of engineering/ university of baghdad (received 29 august 2005; accepted 27 october 2005) abstract: in the present work a dynamic analysis technique have been developed to investigate and characterize the quantity of elastic module degradation of cracked cantilever plates due to presence of a defect such as surface of internal crack under free vibration. a new generalized technique represents the first step in developing a health monitoring system, the effects of such defects on the modal frequencies has been the main key quantifying the elasticity modulii due to presence any type of unvisible defect. in this paper the finite element method has been used to determine the free vibration characteristics for cracked cantilever plate (internal flaws), this present work achieved by different position of crack. stiffness reduction in term of elastic material properties is analyzed through a parametric study of crack density factor. results are given for young’s modulus and shear modulus variation with respects the vibrational characteristics. key words: free vibration, cantilever plate, stiffness degradation. 1. introduction in many branches of modern engineering the vibration of cantilever plate, plays an important role in the design and operation of the final engineering systems. whether one is concerned with propellers, turbine cantilever plates, or satellite booms, where the vibrational behaviors of such system is perpendicular to the plane of rotation, this behavior is one of the most serious problems that should be studied and considered. basically in the most general terms damage can be defined as changes introduced into system that adversely affect the future performance of the plate structure. thus, the study of damage identification in structures will be limited to changes of material and for/or geometric properties, but still the need for the ability to monitor and detect damage at earliest possible stages is objected engineering aim. such investigations of damaged plates are determined whether the damage dr: hussain a.dawood /al-khwarizmi engineering journal ,vol.1, no. 2,pp 86-102 (2005) ٨٧ recognized by measuring the vibration characteristics so that, severe damage can be prevented, the need for quantitative global damage detection techniques that can be applied to complex structures. this vibration based damaged defection is deals with the significantly alter the stiffness, mass or energy dissipation properties of plates. such structural element in rotor craft requires assessment of their dynamic tolerance, and then accurately predicting technique tool for the behavior of damaged structure [1]. the dynamic analysis under present of internal (invisible) flaws is an important issue of the structural investigation and design, and determine the free vibration characteristics often appears to be the fundamental task in dynamic analysis [2]. carnaege studied the vibration of cantilever plate by using the energy method [3]. the increment of strain energy due to rotation was first investigated. further studies of the vibration characteristics of thin cantilever plates using the finite difference method [4] and the extended holzer’s method [5] were presented by carnaege and co-workers. krupka and baumanis [6] studied the bending bending mode of a cantilever plate including rotary inertia and shear deflection by the myklestad method. stafford and giurgiutiu [7] used a semi-analytic method based on transfer matrix method to study a timoshenko beam. abbas [8] and thomas and abbas [9] developed a finite element model which can satisfy all the geometric and natural boundary conditions of athick non-cantilever plate. abbas [10] further used the finite element model for a thick cantilever plate with flexible root. the effect of the local flexibility of a cracked column upon its buckling load was studied by liebowitz et al. [11,12] and okamura et al. [13]. riceand levy [14] recognized the coupling between bending and extensional compliance of a cracked column in compression. dimargonas [15], dimargonas and paipetis [16] and chondros and dimargonas [17] studied the effect of cracks upon the dynamic behavior of cracked beams. the effect of peripheral cracks upon the torsional vibration of a rod of circular crosssection was studied by dimarogonas and paipetis [16]. recently, design for durability can be important reason for the long time material performance, thus for a rotational design it is necessary to quantify the damage tolerance of the cantilever plate. the assessment of this tolerance requires a capability to simulate the progressive damage and cracks characters of structures and loading. a different type of defects and typical notable in cantilever plates and the presence of these defects changes the dynamic characteristics of structure [18]. these changes can be used to identify the existence location and magnitude of effect damage, before they can grow to their critical size [17]. the present work will be concerned with the main macroscopic effects of cracks on cantilever plates, where such defects effects is reduction of stiffness. where it is more deterministic than strength, such reduction can be related to physical damage, in present work the characteristics features of the stiffness reduction cantilever plate will be considered, and investigated under unique boundary condition, while the material properties presented by elastic module take as variable, it must be realized that the changes in deformations response are given by the total changes in stiffness matrix if the crack is presence and characterized. dr: hussain a.dawood /al-khwarizmi engineering journal ,vol.1, no. 2,pp 86-102 (2005) ٨٨ 2. theory in the present work, the finite element formulation for a superparametric shell element is introduced followed by the required procedure to evaluate the eignvalue problem, for calculating natural frequencies, the present proposed technique, proceed for investigate the influence of cracks. the present element is a modified form of shell element described by ahmed [20] is selected. the super parametric shell element with eight nodes and five degree of freedom at each node is investigated. it is presented by zienkiewicz [21]. which the geometric shape functions are higher order than the displacement shape functions. the element is called a superparametric element. if the reverse the element is called subparametric. the superparametric shell elements are derived from the original threedimensional isoparametric elements. the development and application of isoparametric family of elements is presented by zienkiewicz [21]. 2.1. free vibration analysis if any elastic structures are disturb in an appropriate manner initially at t=0, the structure can be made to oscillate harmonically. this oscillatory motion is a characteristic property of the structure and it depends on the distribution of mass and stiffness in the structure rao [19]. the oscillatory motion occurs at certain frequencies known as natural frequencies or characteristic values, and it follows well define deformation patterns known as mode shapes or characteristic modes. the equation of motion by assuming the external force vector {r} to be zero; i.e. homogenous equation; and the displacements to be harmonic [22] so: [m]{u&& }+[k]{u}=0 …(1) ui =φi sin (ωi t+θi) i=1,2,….dof …(2) in this harmonic expression, φi is a vector of nodal amplitudes (mode shape) for the ith mode of vibration. the symbol ωi represents the angular frequency of mode i, and θi denotes the phase angle. by differentiating eq. (2) twice with respect to time t to get: )sin(2 iiiii tu θωω +φ−=&& …(3) substitution of eq. (3) and eq. (2) into eq. (1) allows cancellation of the term sin (ωi t+θi), which leaves, 0])[]([ 2 =φ− ii mk ω …(4) eq. (4) has the form of the algebraic eigenvalue problem. the most efficient type of eq. (4) for structural vibrations accepts the eigenvalue problem only in the following standard, symmetric form: 0])[]([ =− ii xxia λ … (5) in which [a] is a symmetric matrix (dynamic matrix) and [i] is an identity matrix. the symbol iλ denotes the ith eigenvalue. and xxi is the corresponding eigenvector for a new system of homogeneous equations. putting eq. (4) into form of eq. (5) by factoring either matrix [k] or matrix [m], using the cholesky square root method (which is a direct method for solving a linear system which makes use of the fact that any square matrix [a] can be expressed as the product of an upper and lower triangular matrix, weaver [22] ). the step solution to solve eq. (4) by using this method (if the stiffness matrix is positive definite) was: dr: hussain a.dawood /al-khwarizmi engineering journal ,vol.1, no. 2,pp 86-102 (2005) ٨٩ achoosing of factor [k] for an important reason that will soon be apparent. thus: [k]=[q]t [q] …(6) where the factor [q] is an upper triangular matrix, bsubstituting eq. (6) into eq. (4) to obtain: 0])[][]([ 2 =φ− ii t mqq ω … (7) cpre-multiply this equation by [q]-t and insert i= [q]-t [q] after matrix [m], which yields: 0])[][]([][ 2 =φ−− ii tt mqqq ω … (8) drearranging terms in reverse order, this found that: ([m a] –λi [i])φai =0 … (9) where, [ma] = [q] -t [m] [q]-1 and 2 i i 1 ω =λ ; φai =[q] iφ ...(10) edetermination the angular frequencies and mode shapes (in original coordinate): aii i i q φ=φ= −1][;1 λ ω … (11) because the matrix ma in the new coordinates is symmetric, all of its eigenvectors are linearly independent. 2.2. crack characteristics modeling dr: hussain a.dawood /al-khwarizmi engineering journal ,vol.1, no. 2,pp 86-102 (2005) ٩٠ following the suggested procedure for the crack characterization of the damage mode and free vibration consideration, for simplicity in one offexist plane, and the thickness of the cracking )( 1t , and )(t is the total thickness of plate. let )(b is the width of a typical crack, which for a uniformly vibrated cantilever plate. the study of cracked cantilever plate is based on the assumption that cracks can be modeled as a statically uniform array localized in a specified position at surface, in transverse direction. usually these cracks almost instantaneously propagate through the thickness of the plate. fig (1) describes schematically the geometrical dimension a of cracked damaged cantilever plate. the damage vector in cantilever plate can be defined as a different mode for presenting the states of defects. in the present work the focusing study on the most common type, which and surface cracks, then the point of concentration subjected to the failure tolerance in working performance of such cantilever plates, so the attempts of the stiffness degrading quantification based on condition of unchanged geometry and boundary condition, and loading where the remain effective parameters still the elastic material properties (i. e ν,,ge ). firstly, it is important to focus the light on the stiffness-damage relation, the connected to dynamic load conditions. consider now load-time history, illustrated in fig (2-a), which induced damage in given cantilever plate [17]. if the loading is interrupted at times )...,,,( 321 etcttt and the cantilever plate is subjected to small, monotonically increasing stress with rotational speed increasing stresses at these times such that no additional damage is induced under these stresses then we might obtain the stressstrain behavior illustrate in fig. (2-b). thus the changes in stiffness with time )(t would reflect the development of damage under the applied load-time history. based on this fact the present study aims for investigation the reduction in modules of elasticity (both of axial, torsional modulus, at the same time it is important to quantify this changes effects in material properties to decide the critical damage tolerances, then therese assessment the cost-effective performance). 3. results and discussion several numerical investigations are conducted to characterize the dynamic detection of cracked cantilever plates under free vibration consideration, comparisons are made between the response of healthy cantilever plate and other cracked ones. then a parametric study is the main purpose of using the developed computer program. firstly results showed this numerical methodology technique a accurately predicts the undamaged reduction in natural frequencies, for comparison examples of detailed validation studies, then a various parameters effects being taken into consideration with a new developed dynamic stiffness degradation of cracked cantilever plate. the present works were compared with experimental and theoretical results in ref. [23] to find the natural frequencies. table (1) explains the current results with experimental and theoretical results in ref. [23], and the values of percentage error with experimental and theoretical results. table (1) shows that the percentage errors between the current results with experimental results are less than the percentage error between the dr: hussain a.dawood /al-khwarizmi engineering journal ,vol.1, no. 2,pp 86-102 (2005) ٩١ experimental results and theoretical results in ref. [23]. the calculating frequencies of cracked plated are proceed the proposed block diagram in fig. (3), [24]. the following case will be used as verification case to the equations derived in this work. the results to be presented here obtained by using the following data [21]: e=200 g mn / , ρ =7850 3/ mkg , 3.0=υ width of cantilever plate )(b =0.025 m, thickness of the cantilever plate )(t =0.011m the numerical values of the fundamental natural frequencies for different length are shown in table (1). the numerical results reported in table (1) show good agreement with the experimental and theoretical results in ref. [23]. for this table, it can be observed that when length decreased, the percentage error increased especially with experimental result. the second set of results will initiate the tendency of changes in the elastic parameters with the variation of crack location and relatively length. in figs.(4),(5),(6),(7) the percentage loss in elastic modules with different location of crack (l1/l)at certain relatively crack length(t1/t), are seems logically changes, in dramatic form , where it is maximum near the fixed end , then decreases as far as the crack tends to be closer from the free end, these values starts with 5% approximatly closer to clamped edge , and tends to 1.5% at (l1/l) =0.4, the same trend can be noticed from all mentioned figures but with different grades. in the next demonstrated figures, are shows the inversely relatively crack length variation at different location. the figs. (8), (9), (10) and (11), shows the percentage losses in elastic modulus with quantification values. the distinguished changes from these figures indicates the increasing of these quantified losses values with increasing relatively crack depth it can be noticed clearly, and such behavior refer to the clear degradation in stiffness. the normalized elastic modulus changes with different crack length and location is shown clearly .the degree for stiffening the cracked cantilever plate can be related by recognized the normalized reduction degree for each location and relative length under one crack only. where the resonant frequencies are enforced in iterative process for determining the percent variation in elastic stiffness parameters, where the geometry and boundary conditions are considered fixed parameters under free vibration analysis. .the results from this mode analysis for cracked cantilever plate can be input initially for the iterative during natural frequency calculation where it is used as a designated point for reaching, when some elastic modules are changed. where the recalculation the normalized elastic modules (ec/eh) ratios, the influence of stiffness losses degree on the axial and shear stiffness, are well documented to an accurate variation in elastic modules figures.(12),through (15), shows the percent variation in axial and shear stiffness modules, ratios (ec/eh) ,and (gc/gh) for cracked cantilever plates having such dynamic characteristics , the clear percentage changes are clear starts at 5% for this case study as an example , tends to 2% nearly, free edges .the same note it can be distinguished from the reduction in axial/shear ratio variation with different cracks length or location. finally, the correlation between the present reduction, and stiffening in elastic modules ratio with dr: hussain a.dawood /al-khwarizmi engineering journal ,vol.1, no. 2,pp 86-102 (2005) ٩٢ different crack length or location on dynamic characteristics detection signifies the importance of plate stiffness .and more detailed observations can be useful in the development of damage indices for durability detection based on vibration techniques 4. conclusion the present work gives a simplified design methodology for determining the dynamics stiffness characteristics degradation based on the crack location and thickness variety. this design methodology is can be provide a design charts for any types of surface damages. the conclusions obtained from the present analysis can be summarized as follows: 1. the crack position is very important and effective on the frequency parameters, the maximum effect of crack occur at the fixed end of cantilever plate and the minimum of crack occur at near of the free end. 2. the maximum value of relative frequency reduction is (4.85%) at ]3.0)/[( 1 =tt and ]0)/[( 1 =ll . 3. the maximum value of relative elastic modulus reduction and relative shear modulus reduction is (9.44%) at ]3.0)/[( 1 =tt and ]0)/[( 1 =ll . dr: hussain a.dawood /al-khwarizmi engineering journal ,vol.1, no. 2,pp 86-102 (2005) ٩٣ table 1. values of the fundamental natural frequencies for different length of cantilever plate. length (m) present exp. ref.[23] theo. ref.[23] error % exp. theo. 0.0635 2268.35 1968.3 2282.20 15.44 0.60 0.0529 3268.49 2736.8 3286.30 19.42 0.54 0.0454 4437.58 3594.7 4473.10 23.44 0.79 0.0397 5803.33 4550.0 5842.40 27.54 0.66 0.0353 7340.22 5513.5 7394.30 33.13 0.73 0.03175 8546.00 6731.80 8358.70 25.61 1.16 table 2. relative elastic modulus reduction variation with varies (t1/t) and (l1/l). ll /1 0 0.1 0.2 0.3 0.4 tt /1 0.02 0.47 0.42 0.33 0.17 0.13 0.04 0.83 0.67 0.53 0.30 0.20 0.06 1.22 0.97 0.74 0.44 0.28 0.08 1.65 1.28 0.94 0.60 0.36 0.10 2.11 1.62 1.17 0.75 0.45 0.12 2.59 1.98 1.45 0.93 0.56 0.14 3.14 2.38 1.72 1.12 0.67 0.16 3.72 2.80 2.08 1.31 0.81 0.18 4.35 3.27 2.38 1.54 0.92 0.20 5.02 3.78 2.75 1.78 1.07 0.22 5.77 4.34 3.15 2.05 1.22 0.24 6.77 4.95 3.58 2.34 1.42 0.26 7.45 5.60 4.08 2.67 1.61 0.28 8.40 6.33 4.60 3.04 1.81 0.30 9.44 7.15 5.17 3.44 2.07 dr: hussain a.dawood /al-khwarizmi engineering journal ,vol.1, no. 2,pp 86-102 (2005) ٩٤ table 3. relative frequency reduction variation with varies (t1/t) and (l1/l). ll /1 0 0.1 0.2 0.3 0.4 tt /1 0.02 0.25 0.22 0.18 0.10 0.08 0.04 0.43 0.35 0.27 0.17 0.11 0.06 0.63 0.50 0.38 0.24 0.15 0.08 0.84 0.66 0.49 0.31 0.20 0.10 1.07 0.83 0.61 0.39 0.24 0.12 1.32 1.01 0.74 0.48 0.29 0.14 1.59 1.21 0.88 0.57 0.35 0.16 1.89 1.43 1.04 0.67 0.41 0.18 2.21 1.67 1.21 0.79 0.48 0.20 2.56 1.92 1.39 0.91 0.55 0.22 2.94 2.21 1.60 1.05 0.63 0.24 3.35 2.52 1.82 1.19 0.72 0.26 3.81 2.86 2.06 1.36 0.82 0.28 4.31 3.23 2.33 1.54 0.93 0.30 4.85 3.65 2.63 1.74 1.05 table 4. relative shear modulus reduction variation with varies (t1/t) and (l1/l). ll /1 0 0.1 0.2 0.3 0.4 tt /1 0.02 0.47 0.42 0.34 0.17 0.13 0.04 0.83 0.68 0.52 0.30 0.20 0.06 1.22 0.96 0.74 0.44 0.29 0.08 1.65 1.27 0.94 0.60 0.36 0.10 2.11 1.63 1.17 0.75 0.46 0.12 2.59 1.99 1.46 0.94 0.56 0.14 3.15 2.38 1.73 1.12 0.68 0.16 3.73 2.80 2.08 1.31 0.83 0.18 4.36 3.28 2.38 1.55 0.91 0.20 5.02 3.77 2.76 1.78 1.07 0.22 5.77 4.34 3.15 2.05 1.22 0.24 6.57 4.95 3.58 2.34 1.42 0.26 7.45 5.60 4.08 2.68 1.61 0.28 8.40 6.33 4.60 3.04 1.82 0.30 9.45 7.15 5.17 3.45 2.07 dr: hussain a.dawood /al-khwarizmi engineering journal ,vol.1, no. 2,pp 86-102 (2005) ٩٥ (a) t1 t2 t3 t σ t=0 t1 t2 t3 ε σ (b) fig. 2 (a) a load-time history (b) stress-strain response at various times in load-time history b 1t (a) (b) fig. 1 (a) the cracked cantilever plate. (b) the section of side view of crack. d t dr: hussain a.dawood /al-khwarizmi engineering journal ,vol.1, no. 2,pp 86-102 (2005) ٩٦ • compute the damaged frequency nω • compute the percentage frequency reduction )( hch ωωω − *100 start • geometric & mode specifications • (health laminates), bcs • material properties (e, g) modal analysis (numerical free vibration) out put health natural frequency ( nω ) stiffness degradation loop (i) cracked modeling quantifying frequency % shifting quantifying material properties % reduction e, g loop (ii) modal analysis of health with new properties ( nω ) e % g % if )()( ch ωω = no yes print % reduction fig. 3 the typical block diagram of the present stiffness reduction of cracked cantilever dr: hussain a.dawood /al-khwarizmi engineering journal ,vol.1, no. 2,pp 86-102 (2005) ٩٧ 0 0.5 1 1.5 2 2.5 l1/l l1 / l = 0 l1 / l = 0.1 l1 / l = 0.2 l1 / l = 0.3 l1 / l = 0.4 0 1 2 3 4 5 6 l1/l [(e he c) /e h] *1 00 l1 / l = 0 l1 / l = 0.1 l1 / l = 0.2 l1 / l = 0.3 l1 / l = 0.4 0 2 4 6 8 10 l1/l [(e he c) /e h] * 1 00 l1 / l = 0 l1 / l = 0.1 l1 / l = 0.2 l1 / l = 0.3 l1 / l = 0.4 0 2 4 6 8 10 t1 /t [(e he c) /e h] *1 00 t1 /t=0 .06 t1 /t=0 .12 t1 /t=0 .18 t1 /t=0 .24 t1 /t=0 .30 fig. 4 variation of relative elastic modulus reduction with different (l1/l) at (t1/t=0.1) fig. 5 variation of relative elastic modulus reduction with different (l1/l) at (t1/t=0.2) fig. 6 variation of relative elastic modulus reduction with different (l1/l) at (t1/t=0.3) fig. 7 variation of relative elastic modulus reduction with different (t1/t) at (l1/l=0) dr: hussain a.dawood /al-khwarizmi engineering journal ,vol.1, no. 2,pp 86-102 (2005) ٩٨ 0 1 2 3 4 5 6 t1 /t [(e he c) /e h] *1 00 t1 /t =0 .06 t1 /t =0 .12 t1 /t =0 .18 t1 /t =0 .24 t1 /t =0 .30 0 0.5 1 1.5 2 2.5 t1 /t [(e he c) /e h* 10 0] t1 /t=0 .06 t1 /t=0 .12 t1 /t=0 .18 t1 /t=0 .24 t1 /t=0 .30 0.970 0.975 0.980 0.985 0.990 0.995 1.000 l1/l e c/ e h l1 /l=0 l1 /l=0.1 l1 /l=0.2 l1 /l=0.3 l1 /l=0.4 0.930 0.940 0.950 0.960 0.970 0.980 0.990 1.000 l1 /l e c/ e h l1 /l=0 l1 /l=0.1 l1 /l=0.2 l1 /l=0.3 l1 /l=0.4 fig. 8 variation of relative elastic modulus reduction with different (t1/t) at (l1/l=0.2) fig. 9 variation of relative elastic modulus reduction with different (t1/t) at (l1/l=0.4) fig. 10 variation of relative elastic modulus ratio with different (li/l) at (t1/t=0.1) fig. 11 variation of relative elastic modulus ratio with different (li/l) at (t1/t=0.2) dr: hussain a.dawood /al-khwarizmi engineering journal ,vol.1, no. 2,pp 86-102 (2005) ٩٩ 0 .8 6 0 0 .8 8 0 0 .9 0 0 0 .9 2 0 0 .9 4 0 0 .9 6 0 0 .9 8 0 1 .0 0 0 l 1 /l e c/ e h l 1 /l=0 l 1 /l=0 .1 l 1 /l=0 .2 l 1 /l=0 .3 l 1 /l=0 .4 0 .86 0 0 .88 0 0 .90 0 0 .92 0 0 .94 0 0 .96 0 0 .98 0 1 .00 0 t 1 /t e c/ e h t 1 /t=0 .0 6 t 1 /t=0 .1 2 t 1 /t=0 .1 8 t 1 /t=0 .2 4 t 1 /t=0 .3 0 0.920 0.930 0.940 0.950 0.960 0.970 0.980 0.990 1.000 t1 /t e c/ e h t1 /t =0 .06 t1 /t =0 .12 t1 /t =0 .18 t1 /t =0 .24 t1 /t =0 .30 0.970 0.975 0.980 0.985 0.990 0.995 1.000 t1 /t e c/ e h t1 /t =0 .06 t1 /t =0 .12 t1 /t =0 .18 t1 /t =0 .24 t1 /t =0 .30 fig. 12 variation of relative elastic modulus ratio with different (li/l) at (t1/t=0.3) fig. 13 variation of relative elastic modulus ratio with different (t1/t) at (l1/l=0) fig. 14 variation of relative elastic modulus ratio with different (t1/t) at (l1/l=0.2) fig. 15 variation of relative elastic modulus ratio with different (t1/t) at (l1/l=0.4) dr: hussain a.dawood /al-khwarizmi engineering journal ,vol.1, no. 2,pp 86-102 (2005) ١٠٠ 5. references 1. andrew .m. erian . a, ” influence of damage on the elastic behavior of beams”, inter. journal americal hclicopter sol. 55 th, amual forum ,may 1999. 2. int. jouml structunal engineering and mechanics vol. (14), no.3(2002)245-202 3.w. carnegie, “vibrations of rotating cantilever blading” , theoretical approaches to the frequency problem based on energy methods. j. mech sci. 1, 235-240 (1959). 4.w. carnegie, c. stirling and j. fleming, “vibration characteristics of turbine blading under rotation results of an initial investigation and details of high speed test installation. proc. inst. mech. engrs 180, 1-9 (1966).. 5.w. carnegie and j. s. rao, “effect of pretwist and rotation on flexural vibrations of cantilever beams treated by the extended holzer method” bull. mech. engng eduction 10, 1971. 6.r. m. krupka and a. m. baumanis, “ bending-bending mode of a rotating tapered twisted turbomachine blade including rotary inertia and shear deflection” , j. engng. ind., asme 91, 1017 (1969). 7.r. o. stfford and v. giurgiutiu, “ semi-analytic methods for rotating timoshenko beams”. int. j. mech. sci. 17, 719-727 (1975). 8.b. a. h abbas, “ simple finite elements for dynamic analysis of thick pre-twisted blades ”. aeronaut. jnl, 450-453 (1979). 9.j. thomas and b. a. h. abbas,” finite element model for dynamic analysis of timosheno beam”. j. sound vibr. 41, 291-299 (1975). 10.b. a. h. abbas, “ dynamic analysis of thick rotating blade with flexible roots”. aeronaut. jnl, 10-16 (1985). 11.h. liebowiz, h. venderveldt and d. w. harris, “carrying capacity of notched column”. int. j. solids struct. 3, 489-500 (1967). 12.h. liebowiz and w. d. s. claus, jr, "failure of notched column", engng fract. mech. 1, 379-383 (1969). 13.h. okamura et al. , "acracked column under compression", engng fract. mech. 1, 547 (1969). 14.j. r. rice and n. levy, "the partthrough surface crack in an elastic plate", j. appl. mech. 185 (1975). 15.a. d. dimargonas, "vibrations engineering", west, st. paul (1976). 16.a. d. dimargonasand s. a. paipetis, "analytical methods in rotor dynamics". applied science, barking, u. k. (1983). 17.t. g. chondros and a. d. dimargonasand, "identification of cracks in welded joints of complex structures", j. sound vibr. 69, 531 (1980). 18.ramesh t, “stiffness properties of composites”, j. int. j. of fracture mechanics, vol(25) 12, pp (751), (1986). 19.rao s. s. “finite element method in engineering”, pergamon press, oxford, 1982. 20.ahmad s, irons b., zienkiewicz o. c. “analysis of thick and thin shell structures by curved elements”, i. j. for numerical methods in eng., vol. 2, pp. 419-451, 1989. 21.o. c. zienkiewicz, “the finite element method”, 3rd ed., mc grawhill book company (uk) limited, london, 1977. 22.wiilliam weaver and paul. r. johnston, “structural dynamic by finite elements”, standford university, pretice-hall inc., n. j., 1987. 23.b. a. h. abbas and h. irretiev, “experimental and theoretical investigation of the effect of root flexibility on the vibration characteristics beam”, j. of sound and vibration, vol.130, no. 3, pp. 353362, (1989). 24. adnan. n. j. muhsin j. jweeg, hussain a. d,"determination of dr: hussain a.dawood /al-khwarizmi engineering journal ,vol.1, no. 2,pp 86-102 (2005) ١٠١ dynamic characteristics, and inter laminar shear stress of composite plate under various loading", phd. theses uni. of baghdad, college of engg. mech. dept, 2004. 6. nomenclature: t : thickness of the cantilever plate (m) 1t : thickness of the crack (m) 1l : the location of the crack (m) l : the length of the cantilever plate (m) b : the width of the cantilever plate (m) he : health modulus of elasticity 2/ mn ec : cracked modulus of elasticity 2/ mn hg : health modulus of rigidity 2/ mn cg : cracked modulus of rigidity ]100*)/)[(( hc eee − : relative elastic modulus reduction )/( hc ee : relative elastic modulus ratio )/( hc gg : relative shear modulus ratio ]100*)/)[(( hch ggg − : relative shear modulus reduction 100*]/)[( hch ωωω − : relative frequency reduction d=0.05 mm dr: hussain a.dawood /al-khwarizmi engineering journal ,vol.1, no. 2,pp 86-102 (2005) ١٠٢ تحليل االهتزاز الحر لتكميم الجساءة لعتبة كابولية عدي ابراهيم عبد اهللا حسين علي داود .د كلية الهندسة/ كلية الهندسة جامعة بغداد / جامعة بغداد النووية قسم الهندسة الميكانيكيةقسم الهندسة :خالصةال عتبـة تم في هذا العمل تقديم تقنية عددية لتحليل والتوصيف الديناميكي لالنحدار في قيم الجساءة المرنة فـي التقنية العامة المقدمة تمثل الخطوة األولى في منظومة عمـل سـالمة . مثل التشقق"داٍخليا" كابولية تعاني عيبا ات على قيم الترددات الطبيعية مثل نقطة تقويم و تكمـيم تأثير وجود هذه العيوب والتشوه.الهياكل وتشخيصها تـم في هذا البحـث .مستويات االنحدار في قيم ثابت المرونة الهندسي لهذه الهياكل بوجود عيوب غير ظاهرية ق مثل التشق"داٍخليا" كابولية تعاني عيبا ة لعتبةالمواصفات االهتزازية الحرإليجاد استخدام تقنية العناصر المحددة قيم االنحدار في الجساءة بداللة الثوابت الهندسية المرنة ثـم تحليـل وفـق أن. وقعموبوجود شقوق متغيرة ال وباالعتماد على قيم .النتائج التي تم الحصول عليها وكذلك تقديم دراسة معلميه بداللة معامالت تصميميه أساسية .الهتزازيةالهندسية نسبة إلى المواصفات ا و الجساءة معامل المرونة رنا وماجد ومحمد al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 9, no. 1, p.p. 83-93 (2013) mechanical properties and corrosion behavior of low carbon steel weldments rana a.majed majid h. abdulmajeed mohamed mahdy department of materials engineering/ university of technology (received 10 april 2012; accepted 18 february 2013) abstract this research involves studying the mechanical properties and corrosion behavior of “low carbon steel” (0.077wt% c) before and after welding using arc, mig and tig welding. the mechanical properties include testing of microhardness, tensile strength, the results indicate that microhardness of tig, mig welding is more than arc welding, while tensile strength in arc welding more than tig and mig. the corrosion behavior of low carbon weldments was performed by potentiostat at scan rate 3mv.sec-1 in 3.5% nacl to show the polarization resistance and calculate the corrosion rate from data of linear polarization by “tafel extrapolation method”. the results indicate that the tig welding increase the corrosion current density and anodic tafel slop, while decrease the polarization resistance compared with unwelded low carbon steel. cyclic polarization were measured to show resistance of specimens to pitting corrosion and to calculate the forward and reveres potentials. the results show shifting the forward, reverse and pitting potentials toward active direction for weldments samples compared with unwelded sample. keywords: low carbon steel, acr, mig and tig welding, mechanical properties of weldments, corrosion behavior of weldments, tafel extrapolation. 1. introduction the corrosion behavior of carbon steel weldments is dependent on a number of factors. consideration must be given to the compositional effects of low carbon steel and welding consumable and to the different welding processes used. because carbon steels undergo metallurgical transformations across the weld and heat-affected zone (haz), microstructures and morphologies become important. a wide range of microstructures can be developed based on cooling rates, and these microstructures are dependent on energy input, preheat, metal thickness (heat sink effects), weld bead size, and reheating effects due to multiphase welding. as a result of their different chemical compositions and weld inclusions (oxides and sulfides), weld metal microstructures are usually significantly different from those of the haz and base metal. similarly, corrosion behavior can also vary [1]. in addition, hardness levels will be the lowest for high heat inputs, such as those produced by submerged-arc weldments, and will be highest for low-energy weldments (with faster cooling rates) made by the shielded metal arc processes. depending on the welding conditions, weld metal microstructures generally tend to be fine grained with basic flux and somewhat coarser with acid or rutile (tio2) flux compositions. during welding, the base metal, haz, and underlying weld passes experience stresses due to thermal expansion and contraction. upon solidification, rather high levels of residual stress remain as a result of weld shrinkage. stress concentration effects as a result of geometrical discontinuities, such as weld reinforcement and lack of full weld penetration (dangerous because of the likelihood of crevice corrosion and the possibility of fatigue cracking), are also important because of the possibility of stress corrosion cracking scc. achieving full weld penetration, minimizing excessive weld reinforcement through rana a.majed al-khwarizmi engineering journal, vol. 9, no.1, p.p. 83-93 (2013) 84 control of the welding process or technique, and grinding (a costly method) can be effective in minimizing these geometric effects. a stressrelieving heat treatment is effective in reducing internal weld shrinkage stress and metal hardness to safe levels in most cases. this phenomenon has been observed in a wide range of aqueous environments. the common link being that the environments are fairly high in conductivity, while attack has usually, but not invariably, occurred at ph values below about 7 to 8. the reasons for localized weldment attack have not been fully defined. there is clearly a microstructural dependence, and studies on hazs show corrosion to be appreciably more severe when the material composition and welding are such that hardened structures are formed. it has been known for many years that hardened steel may corrode more rapidly in acid conditions than fully tempered material, apparently because local microcathodes on the metal surface stimulate the cathodic hydrogen evolution reaction. on this basis, water treatments ensuring alkaline conditions should be less likely to induce haz corrosion, but even at phs near 8, hydrogen ion (h+) reduction can account for about 20% of the total corrosion current; ph values substantially above this level would be needed to suppress the effect completely [1]. it is probable that similar microstructural considerations also apply to the preferential corrosion of weld metal, but in this case, the situation is further complicated by the presence of deoxidation products, their type and number depending largely on the flux system employed. consumable type plays a major role in determining weld metal corrosion rate, and the highest rates of metal loss are normally associated with shielded metal arc electrodes using a basic coating. in seawater, for example, the corrosion rate for a weld made using a basic-coated consumable may be three times as high as for weld metal from a rutile-coated consumable. fewer data are available for submerged-arc weld metals, but it would appear than they are intermediate between basic and rutile shielded metal arc electrodes and that a corrosion rate above that of the base steel can be expected. galvanic-corrosion effects have also been observed and have caused unexpected failure of piping tank age and pressure vessels where the welds are anodic to the base metal. there is no doubt that residual welding stresses can cause scc in environments in which such failure represents a hazard. this is the case for failure by both active path and hydrogen embrittlement mechanisms, and in the latter case, failure may be especially likely at low heat input welds because of the enhanced susceptibility of the hardened structures inevitably formed. most scc studies of welds in carbon and carbon-manganese steels have evaluated resistance to hydrogen-induced scc, especially under sour (h2s) conditions prevalent to the oil and gas industry [1]. 2. materials and procedure commercial low carbon steel (chemical composition wt%: 0.077 c, 0.309 mn, 0.003 si, 0.0001 p, 0.021 s, 0.0001 cr, 0.0002 mo, 0.023 cu, 0.0001 ni, 0.003 v and fe remain), have dimensions (20 x 20 x 3 mm) was used in this work. three couples of samples were welded by “mig” welding and the other three couples were welded by arc welding. during mig welding argon gas was used with 100 amp and 25 volt was used and in the arc welding 120 amp and 45 v was used. in order to investigate the microstructure some of the welded pieces were ground using emery paper 100, 240, 320, 600, 800 1000 and 1200p before the heat treatment. then they were polished by alumina solution using “nitel solution” (98% alchohol-2% nitric acid) for 5 sec. the microstructure was studied under reflected light microscope. after preparation the surface specimen, the micro hardness test was achieved, so the microhardness test is a test for mechanical hardness used particularly for very brittle materials or thin surface layer, where only a small indentation may be made for testing purposes. a pyramidal diamond point is pressed into the polished surface of the test material with a known force, for a specified well time, and the resulting indentation is measured using a microscope. the geometry of this indenter is an extended pyramid with the length to width ratio being (7:1) and respective face angles are 172 degrees for the long edge and 130 degrees for the short edge. the depth of the indentation can be approximated as 1/30 of the long dimension. we can obtain the result from the law [2]: ...(1) where l is length of indentation along its long axis, cp is correction factor related to the shape of the indenter, ideally 0.070279 and p is load. rana a.majed al-khwarizmi engineering journal, vol. 9, no.1, p.p. 83-93 (2013) 85 the advantages of the test are that only a very small sample of material is required, and that it is valid for a wide range of test forces. the main disadvantages are the difficulty of using a microscope to measure the indentation (with an accuracy of 0.5μm), and the time needed to prepare the sample and apply the indenter. so we got the micro hardness for three areas, base metal, haz metal and fusion zone with load (9.8kn) all values of microhardness were average of three measurements. after micro hardness test, the tensile strength was measured for the samples, where the σmas or σu is indicated by the maxima of a stress-strain curve and, in general, indicates when necking will occur. this fracture will generally occur at the point of necking. after that heat treatment was done for the samples (arc welding and mig welding) using furnace at temperature 600 °c for time 15 minutes and the cooling was inside the furnace. the microstructure and micro hardness of the samples were measured after heat treatment too with a prior grinding and polishing. to corrosion test, three samples of low carbon steel were welded using arc, mig and tig welding to study effect of these treatments on the corrosion behavior of low carbon steel weldments. after welding all samples and as received specimens were mounted by hot mounting to insulate all but one side with an epoxy resin. the open side was polished mechanically to a mirror finish, rinsed in distilled water and stored in desiccators. the electrolyte reference used was sea water (3.5% nacl). polarization experiments were performed in “winking m lab 200” potentiostat from bank-elektronik with electrochemical standard cell with provision for working electrode, auxiliary electrode (pt electrode), and a luggin capillary for connection with an saturated calomel electrode (sce) reference electrode. electrochemical measurements were performed with a potentiostat at a scan rate 3 mv.sec-1. the main results obtained were expressed in terms of the corrosion potentials (ecorr) and corrosion current density (icorr) in addition to measure the “tafel slops”. 3. results and discussion 3.1. mechanical properties microscopic studies revealed that the base metal are coarser crystalline and elongated before heating becoming finer but still elongated after heating. the welding also affects the crystal size as the grains of the base become finer and equidimensional. however, the crystal size of the fusion zone are coarser and equidimensional before heating becoming elongated and oriented after heating (fig. 1). in arc welding the micro hardness results of the base metal, heat affected zone and fusion zone, before heat treatment, are 188, 185 and 200 kn/mm2 respectively. after heat treatment the micro hardness of the base metal, heat affected zone and fusion zone are 170, 186 and 190 kn/mm2 respectively (table 1). in mig welding the micro hardness results of the base metal, heat affected zone and fusion zone, before heat treatment, are 187, 186 and 222 kn/mm2 respectively. after heat treatment the micro hardness of the base metal, heat affected zone and fusion zone are 155, 163 and 236 kn/mm2 respectively as shown in table (1). but in tig welding the micro hardness results of the base metal, heat affected zone and fusion zone, before heat treatment, are 185, 209 and 255 kn/mm2 respectively. after heat treatment the micro hardness of the base metal, heat affected zone and fusion zone are 190, 200 and 236 kn/mm2 respectively in arc welding the σmax and the σy before heat treatment are 490 and 240 mpa respectively. the σmax and the σy after heat treatment are 395 and 235 mpa respectively as shown in table (2). while in mig arc welding the σmax and the σy before heat treatment are 395 and 390 mpa respectively. the σmax and the σy after heat treatment are 320 and 235 mpa respectively as shown in table (2). but in tig welding the σmax and the σy before heat treatment are 300 and 250 mpa respectively. the σmax and the σy after heat treatment are 370 and 260 mpa respectively it seems evident from the above mentioned tests that tensile strength and microhardness tests of the welded samples before and after heat treatment, has improved after welding. both σy and σmax (obtained directly from a digital apparatus attached to the tensile strength instrument). this behavior can probably attributed to the formation of ferrite in the inclusions, as the heating to high temperature led to the loss of carbon from the surface layer and thus decreasing hardness as shown in the photomicrographs. the photomicrographs (fig. (2)) revealed that most of the background consists of ferrite. the improvement of the mechanical properties, both microhardness and tensile strength, in the mig rana a.majed al-khwarizmi engineering journal, vol. 9, no.1, p.p. 83-93 (2013) 86 welding can be attributed to the fine-grained perlite microstructure owing to the quick cooling. in brief, the arc welded pieces, both before and after heat treatment, lead to improvement in the tensile strength but on the expense of the microhardness, as it is less in comparison of the unwelded samples. this is the result of the ferrite formation in the inclusions. the mig welded samples showed slightly lesser tensile strength results but considerable higher hardness owing to the higher formation of the perlite microstructure. the mig welded samples showed lesser amount of defects than the arc welded samples. comparison of the microhardness test results reveals that the fusion zone of samples after heating in mig and tig welding is the highest reaching 236 kn/mm2, whereas in arc welding the microhardness result after heat treatment is 190 kn/mm2. also the microhardness of the fusion zone in the arc and tig welding decreases from 200 to 190 kn/mm2 and from 255 to 236 kn/mm2 respectively after heat treatment whereas it increases in the mig welding from 222 to 236 kn/mm2. fig. 1. photomicrographs showing the microstructures of the mig arc welded samples showing the base metal, the heat affected zone and the fusion zone, 250x. table 1, results of the microhardness of the arc, mig and tig welding before and after heat treatment. process base metal zone hv kn/mm2 heat affected zone hv kn/mm2 fusion zone hv kn/mm2 arc welding before heat treatment 188 185 200 arc welding after heat treatment 170 186 190 mig welding before heat treatment 187 186 222 mig welding after heat treatment 155 163 236 tig welding before heat treatment 185 209 255 tig welding after heat treatment 190 200 236 rana a.majed al-khwarizmi engineering journal, vol. 9, no.1, p.p. 83-93 (2013) 87 fig. 2. photomicrographs showing the microstructures of the arc welded samples showing the base metal, the heat affected zone and the fusion zone, 250x. table 2, results of the tensile strength of the arc, mig and tig welding before and after heat treatment. process σmax σy arc welding before heat treatment 490 240 arc welding after heat treatment 395 235 mig welding before heat treatment 390 395 mig welding after heat treatment 320 235 tig welding before heat treatment 300 250 tig welding after heat treatment 370 260 3.2. corrosion behavior the variation of “open circuit potential” (ocp) with time was shown in the figure (3) for unwelded and welded low carbon steel samples in 3.5% nacl. the ocp-time measurement is considered as an important parameter for evaluating the stability of the passive film of the specimens. the data in table (3) indicate that all low carbon steel weldments shift the open circuit potential (eoc) toward active direction. thus sample of unwelded low carbon steel thermodynamically less tendency to corrosion. the behavior of weldments gives unstable surface/electrolyte interaction compared with the sample without welding through the variation of potential with time. rana a.majed al-khwarizmi engineering journal, vol. 9, no.1, p.p. 83-93 (2013) 88 fig. 3. variation of potentials with time for as received and weldedlow carbon steel alloy in 3.5% nacl . table 3, corrosion parameters of as received and welded specimens in sea water (3.5% nacl) at room temperature. specimens open circuit potential (-eoc/mv) corrosion potential (-ecorr/mv) corrosion current density (icorr/μa.cm-2) tafel slop (mv.dec-1) -bc +ba polar. resistance (rp/ω.cm2) as received 518 516.3 21.45 124.8 72.80 0.9320 welded with arc 589 635.4 14.26 126.7 91.9 1.6240 welded with mig 592 604.5 17.41 126.2 61.0 1.0270 welded with tig 765 790.9 24.13 96.60 94.5 0.8596 linear polarization of unwelded and weldments show in figs. (4) to (7) respectively. these figures show the cathodic and anodic behavior of samples, the cathodic reaction represent the reduction of oxygen according to the following reaction: o2 + 4e + 2h2o → 4ohˉ while the oxidation of iron represents the anodic reaction as follow: fe → fe2+ + 2e the data of potentiodynamic polarization were listed in table (3). these data show that the corrosion potentials (ecorr) values for weldments shift toward active direction compared with unwelded low carbon steel, and the sequence of negativity of corrosion potentials as follow: ecorr tig welding > arc welding > mig welding. the effect of welding on the corrosion current density (icorr) values indicate that the arc and mig welding decrease the value of corrosion current density of low carbon steel without welding, while the tig welding increases the corrosion current density. the values of cathodic tafel slopes (bc) show little increases in the case of arc and mig welding, while decreases for tig welding. but the anodic “tafel slope” (ba) increases in arc and tig welding and decrease for mig welding sample. the polarization resistance (rp) can be determined from the tafel slopes and according to sterngeary equation [3,4]: ….(2) the results indicate increase in case of arc and mig welding and decreasing the polarization resistance for tig welding sample compared with sample without welding. rana a.majed al-khwarizmi engineering journal, vol. 9, no.1, p.p. 83-93 (2013) 89 cyclic polarization measurements were carried out in order to determine the initiation and propagation of local corrosion, which is associated with the breakdown of passive protective film. the breakdown potential (ebr) is the one at which the anodic current increases considerably with applied potential. the potential, at which the hysteresis loop is completed upon reverse polarization scan, is known as the protective potential or repassivation potential. breakdown potential is a sign of local corrosion but the measure of pitting susceptibility is the difference between the breakdown potential and the repassivation one. the protection potential represents the potential at the intersection of hysteresis curve with passive domain. below this potential the propagation of existing localized corrosion will not occur. if the difference between breakdown and the repassivation potential is increasing, the chance in the appearance of pitting is greater and its propagation in depth is more intense. in other words, the hysteresis loop increases as the susceptibility of material to corrosion increases. the cyclic polarization of unwelded and weldments indicated in fig. (8) to (11) in 3.5% nacl. these figures show that the reverse scan starts right of the forward scan curve, that is, towards the high current density region. this type of cyclic polarization curve is known to be less resist to localized corrosion. the potentials for the forward and reverse scan are more negative than that of unwelded sample, in addition to pitting potentials (epit) values which are more negative than pitting potential of as received sample. the data of forward and reverse scan are listed in the table (4). generally, the data of corrosion test indicate that the welding increase the ability of materials to corrode. the tendency of forward, reverse and pitting potentials for weldments take the following sequence: -efor., -erev. and -epit. tig welding > arc welding >mig welding weldments can experience all the classical forms of corrosion, but they are particularly susceptible to those affected by variations in microstructure and composition. specifically, galvanic corrosion, pitting, stress corrosion, intergranular corrosion, hydrogen cracking, and microbiologically influenced corrosion must be considered when designing welded structures. galvanic couples, although some alloys can be autogenously welded, filler metals are more commonly used. the use of filler metals with compositions different from the base material may produce an electrochemical potential difference that makes some regions of the weldment more active. for the majority of aluminum alloys, the weld metal and the haz become nobler relative to the base metal [5]. certain aluminum alloys, however, form narrow anodic regions in the haz and are prone to localized attack. alloys 7005 and 7039 are particularly susceptible to this problem. there are a number of other common weld deposit/base metal combinations that are known to form galvanic couples. it is common practice to use austenitic stainless steel welding consumables for field repair of heavy machinery, particularly those fabricated from high-strength low-alloy steel. this practice leaves a cathodic stainless steel weld deposit in electrical contact with the steel. in the presence of corrosive environments, hydrogen is generated at the austenitic weld metal cathode, which is capable of maintaining high hydrogen content without cracking. however, the cathodic behavior of the austenitic weld deposit may increase the susceptibility for (scc) in the haz of the high-strength steel. a 40% thermal expansion mismatch between the austenitic stainless steel and ferritic base metal produces a significant residual stress field in the weldment; this residual stress field also contributes to cracking susceptibility. a similar, but more localized, behavior may explain the correlation between stress corrosion cracking susceptibility and the presence of retained austenite in highstrength steel weld deposits. another common dissimilar metal combination involves the use of high-nickel alloys for weld repair of cast iron. fe-55ni welding electrodes are used to make weld deposits that can hold in solid solution many of the alloying elements common to cast iron. furthermore, weld deposits made with fe-55ni welding consumables have an acceptable thermal expansion match to the cast iron. because cast iron is anodic to the high-nickel weld deposit, corrosive attack occurs in the cast iron adjacent to the weld deposit. it is suggested that cast iron welds made with high-nickel deposits be coated (painted) to reduce the susceptibility to selective corrosion attack. plain carbon steel weldments can also exhibit galvanic attack. for example, the e6013 welding electrode is known to be highly anodic to a285 base metal in a seawater environment [6]. it is important to select a suitable filler metal when an application involves a harsh environment. welding can reduce base metal corrosion resistance in aggressive environments. in welding, rana a.majed al-khwarizmi engineering journal, vol. 9, no.1, p.p. 83-93 (2013) 90 heat is generated that produces a temperature gradient in the base metal, i.e. the haz. welding may a so induce residual stresses in the weld area which in certain environments can lead to scc. one of the early corrosion problems related to welding was intergranular attack, iga, in the weld haz. in the temperature range of about 800of to 1650of (425oc to 900oc), carbon combines with chromium to form chromium carbides at the grain boundaries. the area adjacent to the carbides is depleted in chromium. when the carbide network is continuous, the low chromium envelope around grains may be selectively attacked, resulting in intergranular corrosion [7]. table 4, data of cyclic polarization of as received and welded specimens in sea water (3.5% nacl) at room temperature. specimens forward potential (-efor/mv) reverse potential (-erev/mv) pitting potential (-epit/mv) as received 571.4 524.5 478.3 welded with arc 689.6 673.8 666.3 welded with mig 622.7 606.2 589.1 welded with tig 790.3 779.3 771.8 fig. 4. linear polarization for unwelded low carbon steel in 3.5%nacl. fig. 5. linear polarization for arc welded low carbon steel in 3.5%nacl. current density (μa.cm-2) po te nt ia l ( m v ) current density (μa.cm-2) po te nt ia l ( m v ) rana a.majed al-khwarizmi engineering journal, vol. 9, no.1, p.p. 83-93 (2013) 91 current density (μa.cm-2) po te nt ia l ( m v ) fig. 6. linear polarization for mig welded low carbon steel in 3.5%nacl. fig. 7. linear polarization for tig welded low carbon steel in 3.5%nacl. fig. 8. cyclic polarization for as received low carbon steel in 3.5%nacl. fig. 9. cyclic polarization for arc welded low carbon steel in 3.5%nacl. fig. 10. cyclic polarization for mig welded low carbon steel in 3.5%nacl. fig. 11. cyclic polarization for tig welded low carbon steel in 3.5%nacl. current density (μa.cm-2) po te nt ia l ( m v ) current density (μa.cm-2) po te nt ia l ( m v) current density (μa.cm-2) po te nt ia l ( m v ) current density (μa.cm-2) po te nt ia l ( m v ) current density (μa.cm-2) po te nt ia l ( m v ) rana a.majed al-khwarizmi engineering journal, vol. 9, no.1, p.p. 83-93 (2013) 92 4. conclusion the following conclusions can be drawn from the present study: 1. the arc welded pieces, both before and after heat treatment, lead to improvement in the tensile strength but on the expense of the microhardness, as it is less in comparison of the unwelded sample. this is the result of the ferrite formation in the inclusions. 2. the mig and tig welded samples showed slightly lesser tensile strength results but considerable higher hardness owing to the higher formation of the perlite microstructure. 3. the mig and tig welded samples showed lesser amount of defects than the arc welded samples. 4. the welding enhances the corrosion of low carbon steel in sea water, and tig welded more liable to corrosion compared with arc and mig welding. 5. the tig welded samples has more negative corrosion, forward, reverse, pitting potentials. 6. the tig welded samples has the corrosion current density and the highest anodic “tafel slope” and the lowest polarization resistance than other welded samples. 5. references [1] c.g. arnold, "galvanic corrosion measurement of weldments," paper 71, presented at corrosion/ 80, chicago, il, national association of corrosion engineers, march 1980 [2] j. r. davis, "metal handbook", second edition (1998). [3] stern, m., method for determining corrosion rates from linear polarization data, corrosion, vol.14, no.9, 1958,p.440–444. [4] stern m., and geary, a. l., electrochemical polarization i: a theoretical analysis of the slope of polarization curves, journal of the electrochemical society, vol. 104, no. 1, 1957, p.559–563. [5] j.e. hatch, ed., aluminum: properties and physical metallurgy, asm international, 1984, p.283. [6] c.a. arnold, “galvanic corrosion measurement of weldments”, presented at nace corrosion/ 80, chicago, march 1980. [7] basic understanding of weld corrosion, 2006 asm international, www. asminternational.org. )2013(-93 83، صفحة1، العدد9مجلة الخوارزمي الھندسیة المجلد رنا عفیف مجید 93 الكاربون واطيء سلوك التآكل لملحومات الفوالذوخواص المیكانیكیة ال جبار محمد مھدي د عبد المجید ماجد حمی رنا عفیف مجید الجامعة التكنولوجیة /قسم ھندسة المواد الخالصة الكھربائي ولحام القوس ملحومات الفوالذ واطيء الكاربون باستخدام لحام القوسیتضمن ھذا البحث دراسة بعض الخواص المیكانیكیة وسلوك التاكل ل من اختبارالصالدة المجھریة واختبارات المعدني المحمي بالغاز الخامل واللحام بقوس التنجستن المحمي بالغاز الخامل، وقد تضمنت الخواص المیكانیكیة كًال وس التنجستن المحمي بالغاز الخامل ولحام القوس المعدني المحمي بالغاز الخامل على التوالي اكثر صالدة من لحام مقاومة الشد، وتشیر النتائج الى ان لحام ق المعدني المحمي القوس الكھربائي، بینما مقاومة الشد في لحام القوس الكھربائي اكثر مما ھي في لحام قوس التنجستن المحمي بالغاز الخامل ولحام القوس .ملبالغاز الخا كلورید الصودیوم لحساب متغیرات % ٣.٥ملي فولت لكل ثانیة في ماء البحر ٣بمعدل مسح " المجھاد الساكن"وقد اجریت تجارب التاكل باستخدام لتاكل من خالل وقد بینت نتائج التاكل بان اللحام بقوس التنجستن المحمي بالغاز الخامل یزید المیل لحصول ا". طریقة تافل االستقرائیة"التاكل باستخدام .وكذلك النفص في مقاومة االستقطاب مقارنة بالعینة غیر الملحومة" میل تافل االنودي"ارتفاع قیمة كثافة التیار و لمعرفة مدى مقاومة العینات الملحومة لتاكل التنقر، وقد دلت النتائج على ان جھود المسح االمامي والعكسي والتنقر كانت " المسح الحلقي"لقد اجري .اكثر سالبیة مقارنة بالعینة غیر الملحومة عزت سليمان67-59 1 al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 7, no. 3, pp 59 67 (2011) composition and temperature dependence of excess volume of heavy oil-stocks mixtures + (gas oil or toluene or reformate) ezzat n. slaiman* haidar m. al-qamaje** shahad z. atta** * department of petroleum engineering/ university of kirkuk ** department of chemical engineering/ college of engineering/ university of nahrain (received 31 january 2011; accepted 2 jun 2011) abstract binary mixtures of three, heavy oil-stocks was subjected to density measurements at temperatures of 30, 35 and 40 °c. and precise data was acquired on the volumetric behavior of these systems. the results are reported in terms of equations for excess specific volumes of mixtures. the heavy oil-stocks used were of good varity, namely 40 stock, 60 stock, and 150 stock. the lightest one is 40 stock with °api gravity 33.69 while 60 stock is a middle type and 150 stock is a heavy one, with °api gravity 27.74 and 23.79 respectively. temperatures in the range of 30-40 °c have a minor effect on excess volume of heavy oil-stock binary mixture thus, insignificant expansion or shrinkage is observed by increasing the temperature this effect becomes more significant although the heavy oil-stocks is spiked with hydrocarbons like (gas oil, toluene and reformate). blending of heavy oil-stocks with hydrocarbons spikes (gas oil, toluene and reformate) form non-ideal mixtures, for which excess volume can be positive or negative depending on nature species. spiking of heavy oil-stocks with either gas oil or reformate resulted in negative excess volume. this shrinkage is greater for the lowest boiling point spike as in the case of reformate, while, the presence of methyl groups in aromatic rings results in a positive excess volume, as shown in toluene when blended with 40 stock but a negative excess volume was found when blended with 60 stock and 150 stock. the api gravity of heavy oil-stocks has an effect on excess volume when the oil-stocks spiked with hydrocarbons like (gas oil, toluene and reformate). this 40 stocks as a typical light types resulted in minimum negative excess volume of -0.47 at 30 °c, when it was spiked with the gas oil; while the spiked heavy oil-stock with kerosene shows a maximum excess volume of -15.56 at 40 °c. keywords: excess volume, heavy oil-stocks, temperature dependence. 1. introduction when two liquids are mixed together, the resulting changes in physical and thermodynamic properties can be considered as a sum of several contributions due to free volume change, change in energy, change in molecular orientations and steric hindrances. the mixing of different compounds gives rise to solutions that generally do not behave as ideal solutions. a solution which obeys raoult’s and dalton’s laws is said to be an ideal solution. in terms of interaction if unlike molecules interaction are equal with like molecules interaction, the solution is said to be an ideal solution. the deviation from ideality is expressed by many thermodynamic variables particularly by excess or residual extensive properties. excess thermodynamic properties of mixtures are useful in the study of molecular interactions and arrangements [1]. thermodynamic studies provide the additional advantage of using the analysis of microscale interactions for understanding the macroscale behavior of gases and liquids upon mixing. through the last decade, a considerable effort has been developed in the field of thermodynamic properties, although a scarcity of published data is still encountered for the mixtures. such properties are strongly dependent on the hydrogen-bond strength of hydroxyl groups, chain length, isomeric structures, and molecular interactions [2]. excess thermodynamic properties of mixtures provide sight into the molecular interactions ezzat n. slaiman al-khwarizmi engineering journal, vol. 7, no. 3, pp 59 67 (2011) 60 between the various components and can be used for the development of molecular models describing the thermodynamic behavior of mixtures. recently, a considerable upsurge in the theoretical and experimental investigations of the excess thermodynamic properties of binary liquid mixtures has been done [3]. blend of petroleum components having different physical properties, endure a change in excess volumes since their constitutes do not form ideal solutions. in an ideal solution, the total solution volume is equal to the sum of the volumes of the components. for a solution to approach ideality, the molecules of the materials blended together must be similar in size, shape, and properties. if the nature of the components differs appreciably, then deviation from ideal behavior may be expected. this deviation may be either positive or negative; that is, the total volume may be smaller or larger than the volumes of its components [4]. the blending of oil stocks results in volume changes, caused by the nonideal behavior of oil systems as compared with the calculated ideal volume. since the oil industry uses volume measurement in its balances, the apparent discrepancies in material may cause financial complications, which in some cases have led to litigation [4]. the excess volume behavior of heavy oilstocks mixtures is important. since only small amount of database was published, especially on mixtures of heavy oil-stocks with pure hydrocarbons; while no or little studies were published on mixtures of different types of heavy oil-stocks [4]. a full understanding of thermodynamic and transport properties of binary liquid systems is essential in many chemical engineering processes such as design calculation, heat transfer, mass transfer, fluid flow, and so forth [5]. we started a research program on the excess properties of mixtures containing (heavy oil-stocks + spikes). in this work we reported experimental data such as density over the whole range of composition for binary liquid mixtures. density is temperature-dependent; in most cases a fluid has less dense as the temperature rises [6]. the variation of density with temperature is a property of great technical importance, since most petroleum products are sold by volume and specific gravity which are usually determined at the prevailing temperatures rather than at the standard 15.6 °c [7]. the present work is aimed to evaluate the volumetric behavior of blends of the heavy oilstocks at temperature range of 30-40 °c. the work is also extended to study the effect of hydrocarbons spikes such as (gas oil, toluene and reformate) on the excess volume of these mixtures, also in temperature range of 30-40 °c. 2. experimental work three heavy oil-stocks were obtained from aldurra refinery, namely 40 stock, 60 stock, and 150 stock. the lightest one is 40 stock with °api gravity 33.69 while 60 stock is middle type and 150 stock the heaviest of °api gravity 27.74 and 23.79 respectively. the main properties of oil stocks (40 stock, 60 stock, and 150 stock) were measured in al-durra refinery laboratories according to api and astm specification, as listed in table 1. table 1, properties of oil stocks. specification 40 stock 60 stock 150 stock kin. viscosity at 40 °c, cst 18.11 56.12 501.98 kin. viscosity at 100 °c, cst 3.14 7.69 33.38 viscosity index (vi) 95 95 93 specific gravity at 15.6 °c 0.85 0.88 0.90 °api gravity 33.69 27.74 23.79 coc flash,°c n.d. 200-300 290-300 p.m. flash,°c 160 n.d. n.d. pour point,°c -24 -6 -3 sulfur content, wt.% 0.62 1.40 2.00 gas oil was used as petroleum fraction to study the excess volume phenomena of heavy oilstocks. this fraction was supplied by al-duora refinery, while the toluene was supplied from merck company, germany. reformate, supplied from alduora refinery, was used to study the excess volume phenomena of heavy oilstocks. its general properties are about 58 api gravity, initial boiling point 40ºc, end point 200ºc, an octane number of about 91. the method of mixing process occurred by electrical mixer at room temperature (20-25 °c). density measurements was measured just, after preparing the mixtures to avoid deposit formation or vaporizing the light ends. all density measurements are carried out at atmospheric pressure. ezzat n. slaiman al-khwarizmi engineering journal, vol. 7, no. 3, pp 59 67 (2011) 61 the following mixtures were prepared: three heavy oil-stocks binary mixtures, at temperature range of 30 40 °c. binary mixtures of heavy oil-stocks with spikes (gas oil, toluene and reformate), at temperature range of 30 40 °c. fig.1. water bath. density determination of heavy oil-stocks, spikes and their blends was carried out using pyknometer with a size of 50 cm3 according to the standard methods (ip 190) [8]. the pyknometer was placed in a water bath type (julabo f25) as shown in fig. (1), which was capable of maintaining the temperature within an accuracy of ± 0.1 °c. pyknometer and the stopper end were thoroughly cleaned using gasoline and acetone. to eliminate all traces of moisture pyknometer and stopper capillary are dried using hot air. wiping the outside of pyknometer and stopper with a clean, lint-free cloth normally. 3. results and discussion the excess thermodynamic properties such as excess volumes of mixtures of heavy oil-stocks are considerably interested in the field of transportation. normally light oil-stock blendes with medium and heavy oil-stock were used to satisfy such specification for lubricating oil and another uses. although these blends would lend to considerable change into thermodynamic behavior of these mixtures, but it directly led to loss in volume of these mixtures [4]. measurement densities at temperatures range of 30-40 °c for individual oil-stocks are listed in table (2). table 2, densities for individual oil stocks. temperature density in g/cm3 oil-stocks 40 °c 35 °c 30 °c 0.8524 0.8544 0.8566 ρexp stock 40 0.8826 0.8866 0.8886 ρexp stock 60 0.9072 0.9092 0.9112 ρexp stock 150 three binary mixtures of heavy oil-stocks have been prepared. the volumetric behavior of the binary mixtures of heavy oil-stocks with different densities was evaluated. the ideal volume was calculated by a linear expression in terms of mass fraction of blending component as follows [9]. …(1) excess volume is defined by the equation: …(2) where vmix is the actual specific volume, which is equal to 1/ρmix in cm3/kg and ρmix is the measured density in kg/m3. excess volumes for binary heavy oil-stocks mixtures are summarized in tables (3), (4) and (5). table 3, excess volume of binary systems; of stock 40 with stock 60 at 30, 35 and 40 °c. temperature ve stock 40 x2 40 °c 35 °c 30 °c -1.2474 -0.9918 -0.7838 ve exp 0.2 -1.5725 -1.3503 -1.0909 ve exp 0.4 -2.0788 -1.7161 -1.5105 ve exp 0.5 -1.6335 -1.357 -1.1479 ve exp 0.6 -1.1998 -1.0096 -0.7661 ve exp 0.8 ezzat n. slaiman al-khwarizmi engineering journal, vol. 7, no. 3, pp 59 67 (2011) 62 table 4, excess volume of binary systems; of stock 40 with stock 150 at 30, 35 and 40 °c. temperature ve stock 40 x2 40 °c 35 °c 30 °c -3.6435 -2.3717 -2.0589 ve exp 0.2 -4.4801 -3.8262 -3.3522 ve exp 0.4 -5.6093 -4.6623 -3.9800 ve exp 0.5 -4.4510 -3.8554 -3.3812 ve exp 0.6 -3.7838 -2.2953 -1.7825 ve exp 0.8 table 5, excess volume of binary systems; of stock 60 with stock 150 at 30, 35 and 40 °c. temperature ve stock 40 x2 40 °c 35 °c 30 °c -1.1970 -0.7470 -0.5140 ve exp 0.2 -2.2325 -1.9432 -1.0893 ve exp 0.4 -2.3360 -2.2004 -1.5456 ve exp 0.5 -2.1924 -1.8282 -0.9790 ve exp 0.6 -1.2701 -0.7937 -0.5393 ve exp 0.8 if the data in the form of excess volumes are plotted against mass fraction of reference components at temperatures range of 30-40 °c, smooth curves are obtained as shown into figs. (2), (3) and (4). the curves pass through zero at 0 wt% and 100 wt% reference component, while the maximum excess volume occurs at, or close to, mass fraction of 0.5, indicating that ve at this point should be a good indicator of the molecular interactions in the mixtures. excess volumes are negative for (stock 40 + stock 60), (stock 40 + stock 150) and stock (60 + stock 150) mixtures over the mass fraction range, as shown into figs. (2), (3) and (4). both oil stocks mixtures (stock 40 + stock 60 and stock 60 + stock 150) gave approximately the same behavior of excess volume at different temperatures as shown into fig. (5). due to the non-ideal behavior of the system as compared with the calculated ideal volume, it can be also noticed from figs. (2), (3) and (4) that the increase in temperature was accompanied with an increase in the value of ve of binary crude oils. negative ve is obtained over the whole mass fraction range for binary heavy oil-stock mixtures at 30, 35 and 40 °c, under concern. tables (3), (4), and (5) are depicted into figs. (2), (3), and (4) in terms of function of mass fraction. fig.(5) shows maximum negative deviation values of ve for the (stock 40 + stock 150) mixtures (-5.6093 cm3/kg at 40 °c). ve curves are almost symmetric with the occurrence of ve maximum at 0.5 mass fractions. this negative excess volume (shrinkage) cames out from the changes in self-association (inter or intramolecular interactions) and physical interaction (van der waals interaction and dipole– dipole interaction) than generated between like molecules and undo the decreases in the volume [10]. on the other hand, free volume effects, interstitial accommodation or interactions between unlike molecules lead to volume contraction. fig.2. excess volume ve for stock 40 with stock 60 at 30, 35 and 40 °c) fig.3. excess volume ve for stock 40 with stock 150 at 30, 35 and 40 °c. ezzat n. slaiman al-khwarizmi engineering journal, vol. 7, no. 3, pp 59 67 (2011) 63 fig.4. excess volume ve for stock 60 with stock 150 at 30, 35 and 40 °c. fig.5. excess volume ve for binary mixtures of stock oil at 40 °c. table 6, excess volumes ve, for spiked heavy oil-stock at 30, 35 and 40 °c). temperature stock 40 x2 40 °c 35 °c 30 °c reformate toluene gas oil reformate toluene gas oil reformate toluene gas oil -3.9150 1.1529 -1.5108 -3.8057 0.7125 -1.3803 -3.4789 0.4511 -0.5871 0.2 -4.8383 3.1330 -1.7034 -4.4355 1.2779 -1.6439 -4.6910 0.7359 -0.8048 0.4 -7.4587 3.5718 -2.2185 -6.3609 2.4827 -1.8833 -5.1969 1.7242 -1.3024 0.5 -5.1082 2.9824 -1.7896 -4.2851 1.2361 -1.5058 -4.6368 0.7868 -0.9284 0.6 -4.1677 1.2009 -1.4638 -3.7755 0.6504 -1.2144 -3.2529 0.4281 -0.4785 0.8 temperature stock 60 x2 40 °c 35 °c 30 °c reformate toluene gas oil reformate toluene gas oil reformate toluene gas oil -6.9053 -1.3359 -1.7580 -4.8113 -0.9120 -1.4588 -3.9328 -0.6438 -0.8387 0.2 -8.9683 -2.0288 -2.6400 -6.9254 -1.5394 -1.8582 -6.6942 -0.9887 -1.3824 0.4 -10.9243 -2.9151 -3.0878 -9.5726 -2.1099 -2.5500 -8.7438 -1.7571 -1.8798 0.5 -9.2383 -1.8970 -2.4687 -7.1612 -1.3398 -1.8639 -6.7819 -0.8576 -1.3277 0.6 -7.4807 -1.2794 -1.8773 -5.0424 -0.9636 -1.5024 -4.0481 -0.6310 -1.1430 0.8 temperature stock 150 x2 40 °c 35 °c 30 °c reformate toluene gas oil reformate toluene gas oil reformate toluene gas oil -9.8580 -1.1149 -3.5738 -8.6605 -0.9323 -2.1173 -5.7449 -0.5970 -1.3590 0.2 -13.2253 -1.3392 -4.5397 -10.8835 -1.1873 -3.9455 -8.0783 -0.6587 -2.4588 0.4 -15.5622 -1.7155 -5.4360 -14.0229 -1.3139 -3.7366 -11.2640 -0.7806 -5.0172 0.5 -12.8288 -1.2954 -4.7196 -10.8351 1.2624 -4.1536 -7.8434 -0.6445 -2.7736 0.6 -10.2505 -1.0963 -3.8789 -8.6506 0.8964 -2.5497 -5.6497 -0.6138 -1.4146 0.8 the lower values of the ve in comparison to other mixture is the result of the ideality of the stock 40 + stock 60 mixture, i.e. the difference between the mixture volume vmix and the ideal ezzat n. slaiman al-khwarizmi engineering journal, vol. 7, no. 3, pp 59 67 (2011) 64 mixture molar volume videl = xv1 +(1−x)v2 is very small (maximum value of about (-1.51) cm3/kg at 30 ° and 0.5 mass fraction. the three heavy oil-stocks which had been blended with hydrocarbons spikes (gas oil, toluene and reformate), have been subjected to density measurements to evaluate its volumetric behavior at temperature range 30-40 °c. the density data obtained for each heavy oilstock/spike pairs are reported in the form of excess volume ve at a given mass fraction of spike x2 as shown in table (6). if the data in the form of specific excess volume are plotted against mass fraction of spike of blend, smooth curves are obtained as shown in figs. (6), (7) and (8) at 40 °c. the curves pass through zero at 0 wt% spike and 100 wt% spikes, while the maximum excess volume occur at, or close to, mass fraction of 0.5, indicating that ve at this point would be good indication of the molecular interactions in these systems. fig.6. excess volume ve for spiked stock 40 at 40°c. it is generally observed that the addition of middle petroleum fractions, such as gas oil to the three heavy oil-stocks of different densities produces negative excess volumes. in other words "shrinkage" occurs in comparison with the calculated ideal volume; as shown in fig. (9). fig.7. excess volume ve for spiked stock 60 at 40°c. fig.8. excess volume ve for spiked stock 150 at 40°c. fig.9. excess volume ve for binary mixtures of stock oil/ gas oil at 40 °c. ezzat n. slaiman al-khwarizmi engineering journal, vol. 7, no. 3, pp 59 67 (2011) 65 also, the addition of the lowest boiling point spike as in the case of reformate to the three heavy oil-stocks of different densities produces negative excess volumes; in other words "shrinkage" occurs, as shown in fig. (10). this shrinkage effect is directly proportional to the specific gravities of the oil-stocks, thereof when the density of oil-stock increase the negative ve will be increased. as noticed in fig. (10), the derived values of ve for the (reformate + 150 oil stock) mixtures records negative (maximal value at about (-15.56) cm3/kg). fig.10. excess volume ve for binary mixtures of stock oil/ reformate at 40 °c. the negative ve values arise due to the dominance of the following factors [11]: (a) chemical interaction between constituent molecules such as hetero-molecular association through the formation of h-bond, often termed as strong specific interaction. (b) association through weaker physical forces such a dipolar force or any other forces of this kind. (c) accommodation of molecules of one component into the interstitial positions of the structural network of molecules of the other component. (d) geometry of the molecular structure that favors fitting of the component molecules with each other. the blending of heavy oil-stocks with aromatic spikes, such as toluene give a positive ve and negative ve depending upon the specific gravity of heavy oil-stock that blends with it. so that the blending of toluene with stock 40 gives positive excess volume and this phenomena refers to the interactions between molecules that are weak and it is better to say that the interactions between dissimilar molecules are much weaker between the similar ones. give rise positive deviations. but the blending of toluene with stock 60 and stock 150 give negative excess volume and this belong to the effect of the two methyl groups of toluene. the binary mixtures of stock 40 with toluene show positive values of excess volume, and thus exhibit expansion, as shown in fig. (11). this effect is appreciably in relation to the fact, that such compounds are "structure breaking" materials leading to positive excess volume [12]. fig.11. excess volume ve for binary mixtures of stock oil/ toluene at 40 °c. the factors that are mainly responsible for the volume expansion i.e., positive values of ve, are [11]: (a) disruption of one or both components in a solution system. a suitable example of this, is the rupture of h-bonding of one compound by the other, or breaking up of associates held together by weaker physical forces such as dipole or dipole-induced dipole interactions or by any other van der waals forces. (b) the geometry of molecular structure which does not favor fitting of the molecules with each other. ezzat n. slaiman al-khwarizmi engineering journal, vol. 7, no. 3, pp 59 67 (2011) 66 (c) (c) steric hindrance which opposes the proximity of the constituent molecules. the binary mixtures of stock 60, 150 with toluene shows negative values of excess volume over the whole composition range as shown in fig.(11). ve curves are almost symmetric with their maximal point at 0.5 mass fraction. this negative excess volume (shrinkage) come from the changes in self-association (inter or intramolecular) and physical interaction between similar molecules which increase the volume [10]. 4. conclusions it is general, it was observed that the blending of light medium oil-stocks and heavy oil-stock results in volume "losses" caused by the non-ideal behavior of those system as compared with their calculated ideal volumes which is accompany increased by increasing in temperature. also it was shown that the mixing of moderate petroleum fractions, such as gas oil and the addition of lowest boiling point spike as in the case of reformate with heavy oil-stocks produces negative excess volume. while the blends of aromatics hydrocarbons with heavy oil-stocks produces positive excess volume except for stocks 60, 150 at temperature range of 30-40 °c. nomenclature x2 mass fraction of component 2 ve excess volume, cm3/kg ρmix density of the mixture for binary system, g/cm3 ρi density of component i, g/cm3 5. references [1] s. parveen et al, “ultrasonic velocity, density, viscosity and their excess parameters of the binary mixtures of tetrahydrofuran with methanol and o-cresol at varying temperatures", applied acoustics 70 (2009) 507–513. [2] j. m. resa, c. gonz alez, j. m. goenaga and m. iglesias, “temperature dependence of excess molar volumes of ethanol +water + ethyl acetate", journal of solution chemistry, vol. 33, no. 2, february (2004). [3] elaheh k. goharshadi, maryam imani, rayhaneh rahimi-zarei, fahimeh razghandi, maryam abareshi, ali r. berenji, " prediction of excess thermodynamic functions and activity coefficients of some polymeric liquid mixtures using a new equation of state", european polymer journal 46 (2010) 587– 591. [4] thura n. a.,"correction of excess volume of oil stocks", m.sc thesis, nahrain university, baghdad, iraq, 2004. [5] jalal basiri parsa , mahdieh farshbaf haghro, " excess molar volume and viscosity deviation for binary mixtures of polyethylene glycol dimethyl ether 250 with 1,2alkanediols (c3–c6)at t = (293.15 to 323.15) k ", j. chem. thermodynamics 40 (2008) 782–788. [6] hobson, g.d., and pohl w., "modern petroleum technology"., 4th ed., applied science publisher ltd., london, (1975). [7] gruse w.a., and stevens "chemical technology of petroleum "., 3th ed., mc graw – hill, book company & new york, (1960). [8] "standard methods for analysis and testing of petroleum and related products", wiley j., and sons, new york, (1988). [9] ashcroft, s.j., booker d.r. and turner j.c.r., "volumetric behavior of oil mixtures of crude oils and light hydrocarbon", journal of the institute of energy", vol. 65, september, p. 131-136 (1992). [10] jan zielkiewicz, “excess volumes of mixing in (n,n-dimethylacetamide + methanol + water) and (n,ndimethylacetamide + ethanol + water) at the temperature 313.15 k", j. chem. thermodynamics 40 (2008) 431–436. [11] m.m.h. bhuiyan , m.h. uddin, " excess molar volumes and excess viscosities for mixtures of n,n-dimethylformamide with methanol, ethanol and 2-propanol at different temperatures ", journal of molecular liquids 138 (2008) 139–146. [12] shymaa k.a., "effect of the chemical composition on excess volume of mixtures with petroleum fractions", m.sc thesis, nahrain university, baghdad, iraq, 2005. )2011( 59 67 ، صفحة3، العدد 7مجلة الخوارزمي الھندسیة المجلد عزت نیازي سلیمان 67 الزائد لالساسات زیت التزلیق حجمعلى ال ودرجة الحرارة نسب الوزنیةتاثیر ال )الریفورمیت +التلوین +زیت الغاز(ركاربونیة بوجود المضافات الھید **شھد زھیر عطا ** حیدر موفق توفیق * عزت نیازي سلیمان جامعة كركوك/ قسم ھندسة النفط* جامعة النھرین /كلیة الھندسة /قسم الھندسة الكیمیاویة** الخالصة واالثقل وزنا ٦٠خف من حیث الوزن الجزیئي والمتوسط وھو االستوك الوھو ا ٤٠ق وھي االستوك تم استخدام ثالث انواع من اساسات زیت التزلی زیت الغاز(لمعرفة السلوك الحجمي لمخالیط تلك الزویت وكذلك سلوك تلك الزیوت حجمیا عند اضافة المضافات الھیدروكاربونیة مثل ١٥٠جزئیا االستوك دي الى زیادة في الحجم قد تكون موجبة او سالبة بمعنى تؤحیث ان اضافة ھذه المواد . )م° ٤٠-٣٠(ت حرارة متغیرة وكذلك بدرجا) الریفورمیتو التلوین و ادة الحجمیة لكل مزیج تمت یلدرجة الحرارة تاثیر ملحوظ على الز نكما ا. اخر ان ھذه االضافات قد تودي الى انكماش او تمدد حجمي في تلك الخالئط وكذلك المواد یؤدي الى حدوث انكماش ملحوظ في حجم الخالئط ) زیت الغاز(حیث تبین ان اضافة المادة الھیدروكاربونیة ذات الطابع البرافییني . دراستھ یؤدي الى ) ینولتال(بینما اضافة المادة الھیدروكاربونیة ذات الطابع الوروماتي ) الریفورمیت(الھیدروكاربونیة ذات درجة الغلیان الواطى كما ھو الحال في ین الى تلك الخالئط یؤدي الى انكماشھا والسبب في سلوك الزایلین بصورة عامة حیث ان اضافة التلو ٦٠و ١٥٠تمدد تلك الخالئط ماعدا خالئط االستوك االستوك الى الریفورمیتاضافة عند ١٥,٥٦نسبة من الوزن الزائد وھي اعلى تم الحصول على ). التلوین(المثیل في الحلقة تيمجموع یرجع الى وجود ١٥٠ . حسين قاسم حسين29-19 al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 7, no. 3, pp 19 29 (2011) upgrading sharky baghdad heavy crude oil hussain k. hussain* salah m. ali ** yazan m. ali ** * department of chemical engineering/ college of engineering/ university of baghdad ** petroleum research and development center/ ministry of oil (received 28 february 2011; accepted 19 jun 2011) abstract shaky baghdad heavy crude oil 22 api is processed by distillation and solvent extraction. the purpose of distillation is to separate the light distillates (light fractions) which represent 35% of heavy crude oil, and to obtain the reduced crude oil. the heavy residue (9 api) is extracted with iraqi light naphtha to get the deasphaltened oil (dao), the extraction carried out with temperature range of 20-75 oc, solvent to oil ratio 5-15:1(ml:g) and a mixing time of 15 minutes. in general, results show that api of dao increased twice the api of reduced crude oil while sulfur and metals content decreased 20% and 50% respectively. deasphaltened oil produced from various operating conditions blended with the light distillates obtained from distillation in a constant blending percentage of 35% light for all mixtures. these blends produced synthetic crude oil with api up to 30 suitable for using in the subsequent hydrocarbon processes. keyword: synthetic crude oil, deasphaltening, distillation, extraction. 1. introduction asphaltenes are high molecular weight polycyclic compounds containing nitrogen, sulfur, oxygen, and metals. the relative concentrations of these compounds vary in terms of the crude oil, and make up a unity which makes it a useful parameter for general comparisons of oils. all of these compounds are present in different oils which vary from light to heavy crudes with a broad spectrum of varying densities in which the conventional unit of gravity api gravity decreases or the oil becomes heavier, making this unit an important correlational factor. additional general correlational factors describing different types of oils are the h/c ratios, which also decrease as the oil becomes heavier. further, the polar n, s, o compounds become concentrated in the heavy ends of crudes. the heteroatom contents of these oils are measurable quantities and are also useful for correlational purposes. thus, as the sulfur and nitrogen concentrations increase, the api value decreases, consistent with an increase in the concentrations of compounds containing heteroatoms and increasing molecular weights. the high molecular weight fractions also concentrate organometallic compounds [1]. reduction of asphaltenes and metal content can be achieved by disturbing the solvation equilibrium via addition of suitable solvents, e.g., propane, pentane, heptane or carbon dioxide, resulting in the flocculation of asphaltenes [2].the solvent deasphaltation treats the residue through a pressurized liquid-liquid extraction, using specific properties of the solvent. the deasphaltation produces the deasphalted oil and the asphalted residue [3].the residuum oil supercritical extraction process is the premier deasphalting technology available in industry today. this stateof-art process extracts high-quality deasphalted oil (dao) from atmospheric or vacuum residues and other feedstocks. the asphaltene products from the rose process are often blended to fuel oil, but can also be used in the production of asphaltic blending components, solid fuels, or fuel emulsions. the development of the deasphaltation technology using supercritical fluid appears as a solution to improve the separation of the deasphalted oil (odes) from the asphaltenes. the use of supercritical fluid has some advantages like: the difference of the densities between the hussain k. hussain al-khwarizmi engineering journal, vol. 7, no. 3, pp 19 29 (2011) 20 extraction phase and the refining phase is greater than that obtained by the conventional liquid extraction, becoming the separation between the phases easier; the mass transport is faster using the supercritical fluid; the quantity and the quality of the odes can be easily controlled adjusting the temperature and the pressure of the extraction system and the efficiency to recover the oil is a function of the density of the supercritical fluid [3]. the solvent deasphalting process (sda) which is based on liquid–liquid extraction by using paraffinic solvents (c4–c7) is one of the most efficient approaches to reduce metal and asphaltene contents of heavy oil cuts before sending them to hydro-desulphurization and hydrocracking units. a number of deasphalting process parameters are to be considered, amongst which the dao process yield and the levels of demetalization and deasphalting could be noted. the important factors influencing the mentioned parameters are solvent composition and ratio of the solvent to the feed, temperature, pressure and the type of extractor equipment. the precipitation increases substantially as the solvent/feed ratio increases up to 10 folds. beyond this value, precipitation increases by very small amounts [4]. extraction temperature must be maintained below the critical temperature of the solvent, however, because at higher temperatures no portion of the residue is soluble in the solvent and no separation occurs[5]. in industrial plants, increasing the solvent to feed ratio compensates for the dao yield reduction with temperature rise. in consequence, the extraction process selectivity for paraffinic oils escalates and eventually the extracted oil will have an improved quality due to the reduction of undesirable components [6]. direct hydro-desulphurization followed by hydrocracking of crude oil heavy cuts and vacuum residues is one of the best methods of heavy residue upgrading in refining industry. but, problem emerges when metal and asphaltene contents of residue are high. in fact, the presence of these compounds adversely influences the activities of the hydro-desulphurization and hydrocracking catalysts. the aim of this work is to separate the light distillates from sharky baghdad heavy crude oil and to obtain deasphaltened oil by solvent extraction with light naphtha. the light and the blended dao distillate to produce high api synthetic crude oil with low sulfur and metals content. 2. experimental work 2.1. distillation process the distillation process for separation of light distillates (light fractions) from sharky baghdad heavy crude oil was achieved by a computerized laboratory distillation apparatus (according astm 5236) (pignat company, france) that consists of distillation flask, heating mantle, distillation column, condenser, thermometers, fraction collector. the physical properties of sharky baghdad heavy crude oil and distillation results are shown in table (1). figure (1) shows the schematic diagram of the laboratory distillation apparatus. table 1, physical properties of sharky baghdad crude oil. preliminary distillation (ip 24/55) value property vol. % temperature, ºc 0.922 specific gravity 15.6/15.6 ºc ibp(85 ºc) 22 api gravity 3.5 100 47 viscosity at 37.5 ºc, cs 5 125 5.044 sulfur content, wt. % 8.6 150 88 vanadium, ppm 11.6 175 25 iron, ppm 15.1 200 38 nickel, ppm 18.4 225 42.66 saturate compounds, wt. % 23 250 23.87 naphthene compounds, wt. % 27.5 275 17.8 polar aromatic compounds,wt.% 33.7 300 15.67 asphultene content,wt. % hussain k. hussain al-khwarizmi engineering journal, vol. 7, no. 3, pp 19 29 (2011) 21 fig.1. schematic diagram of the laboratory distillation unit. 2.2. extraction process asphaltenes are separated from atmospheric residue (350+oc) obtained from distillation stage by extraction with light naphtha. the composition of light naphtha and the physical properties of atmospheric residue are given in tables 2 and 3, respectively. the extraction process consists of three stages mixing, filtration and solvent recovery. table 2, composition of iraqi light naphtha. n-paraffins wt % i-paraffins wt % naphthenes wt % aromatics wt % c3 0.067 i-c4 0.045 cc5 0.302 benzene 0.683 n-c4 0.329 i-c5 3.956 nc6 4.37 toluene 1.904 n-c5 7.006 2mc5 10.787 cc6 2.844 n-c6 14.809 3mc5 7.421 nc7 4.11 n-c7 10.192 2mc6 6.976 nc8 7.091 3mc6 6.106 table 3, physical properties of atmospheric residue. property value specific gravity 15.6/15.6 ºc 1.002 api gravity 9.66 asphaltenes ,wt % 23 asphaltenes ,g 11.5 sulfur ,wt % 5.7 sulfur ,g 2.85 vanadium ,ppm 90 nickle ,ppm 35.2 chrome ,ppm 2.35 amixing stage mixing was carried out with 1-liter 2-neck glass flask, magnetic stirrer, heating mantle, high efficiency condenser and thermometers. 50 g of atmospheric residue was mixed with light naphtha at temperatures of 20, 50, 75oc, solvent to oil ratio 5, 10, 15:1 (ml:g) and mixing time of 15 minutes with 200 rpm. a high efficient vertical condenser operating at total reflux was mounted on mixing flask in order to decrease the solvent losses to the minimum. figure (2) shows a scheme of mixing process. when the mixing step was complete, the flask left for 1 hour at ambient temperature to let asphaltenes settle to the bottom of the flask. hussain k. hussain al-khwarizmi engineering journal, vol. 7, no. 3, pp 19 29 (2011) 22 fig.2. scheme of the mixing unit. bfiltration in order to filter the solvent-oil mixture in a reasonable time, a vacuum filtration unit was assembled, which consisted of a filtration flask, buchner funnel, vacuum pump and trap for condensing the high volatility solvent in order to avoid vacuum pump damage. the filter paper (whatman no. 1) was wetted with solvent before the filtration step. at the end of the filtration, the filter paper was put in a hot electrical furnace to evaporate the solvent associated with the precipitated asphaltenes. the dried filter paper was then weighed to estimate the percentage of asphaltenes yield. cevaporation solvent and deasphaltened oil is introduced to distillation unite in order to separate the solvent from dao. 2.3. blending dao produced from various operating conditions blended with the light distillates is produced from distillation stage which formed 35% from these mixtures to produce synthetic crude oil. 3. results and discussions the tests results of dao produced from various operating conditions are shown in table (4). the effective parameters of process included in these tables are specific gravity, api, asphaltene content, sulfur and metals content. table 4, tests results of deasphaltened oil. temperature oil:solvent 20 oc 01:05 01:10 01:15 specific gravity 15.6/15.6 ºc 0.946425 0.933993 0.931105 api 18.01 20 20.47 asphaltenes removed,g 8.32 10.5 11 sulfur content, wt% 4.4 4.3 4.4 vanadium,ppm 35 24.6 24 nickle,ppm 16 15.2 14.9 chrome,ppm 0.1 0.1 0.1 after blending api of synthesis crude oil 29.2065 30.5 30.8055 temperature oil:solvent 50 oc 01:05 01:10 01:15 specific gravity 15.6/15.6 ºc 0.946488 0.937086 0.93461 api 18 19.5 19.9 asphaltenes removed,g 7.81 8.2 8.4 sulfur content, wt% 4.5 4.6 4.6 vanadium,ppm 41.4 31 24.3 nickle,ppm 18 17.5 17.1 chrome,ppm 0.6 0.3 0.2 after blending api of synthesis crude oil 29.2 30.175 30.435 temperature oil:solvent 75 oc 01:05 01:10 01:15 specific gravity 15.6/15.6 ºc 0.95634 0.955436 0.9555 api 16.46 16.6 16.59 asphaltenes removed,g 5.1 7.3 7.1 sulfur content, wt% 4.8 4.7 4.6 vanadium,ppm 58.4 57 50.9 nickle,ppm 18.2 18 17.5 chrome,ppm 0.64 0.56 0.3 after blending api of synthesis crude oil 28.199 28.29 28.2835 hussain k. hussain al-khwarizmi engineering journal, vol. 7, no. 3, pp 19 29 (2011) 23 3.1. effect of temperature figure (3) shows that asphaltenes yield decreased with increasing temperature. this behavior is due to increasing the solubility of oil with increasing temperature which permits asphaltenes and resinous materials to escape to the oil phase. figures 4 and 5 show that api of dao and synthetic crude oil decreased with increasing temperature respectively due to decreasing of asphaltenes removal with increasing temperature. figure (6) shows that sulfur content of dao increased with increasing temperature due to the decreasing removal of asphaltenes. a figure 7, 8 and 9 shows that metals impurity reduction of vanadium, nickel and chrome respectively decreased with increasing temperature. these behaviors due to increasing asphaltenes content with increasing temperature. fig.3. effect of temperature on asphaltenes removal from rcr at various oil to solvent ratio. fig.4. effect of temperature on api of deasphaltened oil at various oil to solvent ratio. fig.(1) effect of temp on rem oved asph of rcr 0 5 10 15 20 50 75 tem p.(c) r em ov ed a sp h. 01:05 01:10 01:15 temperature (oc) a sp ha lte ne s r em ov ed (g ) 0 5 10 15 20 25 20 50 75 a pi temperature(°c) 01:05 01:10 01:15 hussain k. hussain al-khwarizmi engineering journal, vol. 7, no. 3, pp 19 29 (2011) 24 fig.5. effect of temperature on api of synthesis crude oil at various oil to solvent ratio fig.6. effect of temperature on sulfur content of deasphaltened oil at various oil to solvent ratio. fig.7. effect of temperature on vanadium reduction of deasphaltened oil at various oil to solvent ratio. 26.5 27 27.5 28 28.5 29 29.5 30 30.5 31 31.5 20 50 75 a pi temperature(°c) 01:05 01:10 01:15 4 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 20 50 75 su lfu r c on te nt (w t% ) temperature(°c) 01:05 01:10 01:15 0 10 20 30 40 50 60 70 80 20 50 75 v an ad iu m r ed uc tio n (w t% ) temperature (°c) 01:05 01:10 01:15 hussain k. hussain al-khwarizmi engineering journal, vol. 7, no. 3, pp 19 29 (2011) 25 fig.8. effect of temperature on nickel reduction of deasphaltened oil at various oil to solvent ratio. fig.9. effect of temperature on chrome reduction of deasphaltened oil at various oil to solvent ratio. 3.2. effect of solvent to oil ratio figure (10) shows the effect of increasing solvent to oil ratio on the removing of asphaltene. in this case, increasing solvent to oil ratio led to increasing asphaltenes removal and then to steady state at 10:1. this behavior is due to increasing solvent power and selectivity toward asphaltenes removal. figures 11 and 12 shows the effect of increasing the solvent to oil ratio on api of dao and synthetic crude oil respectively. in this case, the increasing of solvent to oil ratio led to increase of api due to increasing solvent power and selectivity for the removing of asphaltenes and then to steady state. figure (13) shows approximately steady state effect of increasing the solvent to oil ratio on sulfur content. figures 14, 15 and 16 show the effect of increasing solvent to oil ratio on vanadium, nickel and chrome impurity reduction, respectively. in this case, increasing solvent to oil ratio led to the increasing of metals impurity reduction due to increasing the removing of asphaltenes. 0 20 40 60 80 100 120 20 50 75 01:05 01:10 01:15 temperature (oc) c hr om e r ed uc tio n (w t% ) 42 44 46 48 50 52 54 56 58 60 20 50 75 n ic kl e r ed uc tio n (w t% ) temperature(°c) 01:05 01:10 01:15 hussain k. hussain al-khwarizmi engineering journal, vol. 7, no. 3, pp 19 29 (2011) 26 fig.10. effect of oil to solvent ratio on asphaltenes removal from rcr at different temperatures. fig.11. effect of oil to solvent ratio on api of deasphaltened oil at different temperatures. fig.12. effect of oil to solvent ratio on api of synthesis crude oil at different temperatures. 0 2 4 6 8 10 12 1:05 1:10 1:15 20 50 75 a sp ha lte ne s r em ov ed (g ) oil:solvent ratio (g:ml) 26.5 27 27.5 28 28.5 29 29.5 30 30.5 31 31.5 1:05 1:10 1:15 ap i 20 50 75 oil:solvent ratio (g:ml) 0 5 10 15 20 25 1:05 1:10 1:15 ap i 20 50 75 oil:solvent ratio (g:ml) hussain k. hussain al-khwarizmi engineering journal, vol. 7, no. 3, pp 19 29 (2011) 27 fig.13. effect of oil to solvent ratio on sulfur content of deasphaltened oil at different temperatures. fig.14. effect of oil to solvent ratio on vanadium reduction of deasphaltened oil at different temperatures. fig.15. effect of oil to solvent ratio on nickel reduction of deasphaltened oil at different temperatures. 42 44 46 48 50 52 54 56 58 60 1:05 1:10 1:15 n ic ke l r ed uc tio n (w t% ) oil:solvent ratio (g:ml) 20c 50c 75c 4 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 1:05 1:10 1:15 20c 50c 75c su lfu r c on te nt oil:solvent ratio (g:ml) 0 10 20 30 40 50 60 70 80 1:05 1:10 1:15 20c 50c 75c oil:solvent ratio (g:ml) v an ad iu m r ed uc tio n (w t% ) hussain k. hussain al-khwarizmi engineering journal, vol. 7, no. 3, pp 19 29 (2011) 28 fig.16. effect of oil to solvent ratio on chrome reduction of deasphaltened oil at different temperatures. 4. conclusions 1removing asphaltenes from the reduced crude oil produces dao with 19 api with low sulfur and metals content. 2increasing extraction temperature led to decreasing api of dao and other properties. 3increasing solvent to oil ratio led to increasing api of dao and other properties with no significant changes beyond solvent to oil ratio 10:1 (ml:g). 4optimum extraction process is carried out at temperature 20oc and 10:1 solvent to oil ratio. 5blending of light distillates in a percentage 35% with dao led to producing synthetic crude oil with 30 api and low sulfur and metals content. 5. references [1] e. t. premuzic and m. s. lin, “212th national acs meeting induced biochemical interactions in crude oils”, august 18-22, 1996, orlando, fl. [2] eckermann b. and vogelpohl a., “deasphaltization and demetalling of heavy crude olis and distillation residues with co2”, chemical engineerring and technology. v13,p.258-264, 1990. [3] mendes m. f., ferreira c. z. and pessoa f. l. p., “deasphaltion of petroleum using supercritical propane”. 2nd mercosur congress on chemical engineering, 4 nd mercosur congress on process systems engineering, enpromer, costa verde – brasil, 2005. [4] gonzalez, e. b., c. l. galeana, a. g. villegas, j. wu, aiche journal, vol. 50, no. 10 oct. 2004, p. 2552 [5] meyers, r. a., “handbook of petroleum refining processes”, 10th ed., mcgraw-hill, 2003. [6] ditman, j. g., van hook, j. p. :acs meeting atlanta, april 1981. 0 20 40 60 80 100 120 1:05 1:10 1:15 c hr om e r ed uc tio n (w t% ) oil:solvent ratio (g:ml) 20c 50c 75c )2011( 19 29 ، صفحة3، العدد 7مجلة الخوارزمي الھندسیة المجلد سم حسین احسین ق 29 رفع خواص نفط خام شرقي بغداد الثقیل **یزن مناف ** صالح مھدي *حسین قاسم حسین جامعة بغداد /كلیة الھندسة /قسم الھندسة الكیمیاویة* وزارة النفط/ مركز البحث والتطویر النفطي** الخالصة والتي تمثل ) المقاطع الخفیفة(ان الغرض من التقطیر ھو لفصل المقطرات الخفیفة . یر واالستخالصمعاملة نفط خام شرقي بغداد الثقیل بعملیات التقط قد استخلص بالنافثا العراقیة الخفیفة للحصول على متبقي ٩ان المتبقي الثقیل بثقل نوعي . وللحصول على المتبقي الجوي الثقیل, من النفط الخام الثقیل% ٣٥ بشكل عام فان .دقیقة ١٥وزمن خلط ) غم:مل( ١٥-٥:١نسبة مذیب الى اللقیم , مئویة ٧٥-٢٠االستخالص بمدى درجة حرارة ث تمحی, منزوع االسفلتینیات ى الكبریتي والمعادنالنتائج اظھرت بان الثقل النوعي للثقیل المنزوع االسفلتینیات قد ازداد مرتین بالنسبة الى المتبقي الجوي الثقیل بینما انخفض المحتو خفیف و % ٣٥تم خلط المتبقي منزوع االسفلتینیات مع المقطرات الخفیفة المستحصلة من عملیة التقطیر بنسبة خلط مئویة ثابتة .على التوالي ٥٠%و%٢٠ . مالئم لالستخدام في العملیات الھیدروكاربونیة الالحقة ٣٠ع بثقل نوعي بحدود ھذه االمزجة انتجت نفط خام مصن. لجمیع االمزجة المحضرة (microsoft word \316\341\346\317 \307\323\337\344\317\321129140) al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 14, no. 3, september, (2018) p.p. 129140 modified elman neural-pid controller design for dc-dc buck converter system based on dolphin echolocation optimization khulood e. dagher al-khwarizmi collage of engineering /university of baghdad/ baghdad/ iraq dagherkhulood@kecbu.uobagdad.edu.iq :email (received 25 september 2017; accepted 21 january 2018) https://doi.org/10.22153/kej.2018.01.009 abstract this paper describes a new proposed structure of the proportional integral derivative (pid) controller based on modified elman neural network for the dc-dc buck converter system which is used in battery operation of the portable devices. the dolphin echolocation optimization (deo) algorithm is considered as a perfect on-line tuning technique therefore, it was used for tuning and obtaining the parameters of the modified elman neural-pid controller to avoid the local minimum problem during learning the proposed controller. simulation results show that the best weight parameters of the proposed controller, which are taken from the deo, lead to find the best action and unsaturated state that will stabilize the buck converter system performance and achieve the desired output. in addition, there is a minimization for the tracking voltage error to zero value of the buck converter output, especially when changing a load resistance by 10%. keywords: buck converter, dolphin echolocation, modified elman neural pid controller, on-line-tuning optimization. 1. introduction dc-dc buck convertor is a very versatile electronic circuit due to its essential use in battery operations for different applications such as computer systems, portable devices, office equipment and any other devices that need to get an output voltage more or less than the input voltage. buck convertors acquired their name from the reality of their work, where the amplitude of input voltage is bucked/chopped or decreased to get the output voltage [1]. in fact, the optimal or near optimal control of the attenuation operation is not easy and this is because of the load variation thus, we can find various researches that solve this problem and the backbone for these researches is the famous pid controller which is well known by its structure simplicity, time domain regulation and good closed loop response [2]. hence, many optimization methods are developed to find the control gain parameters for the pid controller that is used to control the buck convertor, and some of these methods are: [3] presented a fuzzy pid controller with no defuzzification module. in [4] the authors proposed a new adaptive method based on simulated annealing algorithm to control the output voltage of the convertor. in [5] the authors proposed an on-line tuning method based on particle swarm optimization and they show high control performance. in addition to that, the genetic algorithm as a tuning control algorithm for buck converter is used as in [6]. this paper presents a new structure of the controller that uses a modified elman neural network in the form of the pid controller equation and the control parameters are tuned by an optimization algorithm named as dolphin echolocation optimization deo algorithm in order to get fast, accurate and robust control action for the dc buck converter. khulood e. dagher al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 129140 (2018) 130 deo was presented by ali in 2013 [7] and proved as the most powerful optimization meta-huristic method as compared with other evolutionary algorithms in terms of the number of function evaluations and in convergence toward reaching the optimal solution. the description of this paper is as follows: section two describes the mathematical model of the dc-dc buck converter. section three explains the design of the proposed modified elman neural-pid controller. in section four, the dolphin echolocation optimization algorithm is explained. section five presents the simulation results of the proposed controller. finally, the conclusions are explained in section six. 2. buck converter circuit model in this work, an asynchronous buck convertor model is used with two n-channel mosfets as shown in figure (1) to make the output voltage vout always less than the supply voltage vs. this converter uses two controllable switches to achieve its operation rather than using one nchannel mosfet power switch and one power diode rectifier, thus it has a maximize conversion efficiency and fast switching transient [4, 8]. fig. 1. schematic diagram of synchronous buck power stage [8]. in general, the operation of the buck converter depends on q1 of the mos switch and q2 of the mos synchronous rectifier. the parameter values of the buck convertor taken from [3, 4] is shown in table 1. now to drive and analyze the mathematical model of the buck convertor two operation time have to be considered depending on two mosfets (q1 and q2) [3, 4] as follows: • at period of time t<t1, switching on q1 and switching off q2: the circuit analysis can be illustrated by applying kirshoff’s voltage law as follows: 0=−⋅−−⋅− outll l onls vri dt di lrsiv …(1) where vs: is the supply voltage; il: is the inductor current; rson: is the on n-channel resistance of the mosfet; rl: is inductor effective series resistance; vout: is the output voltage of the circuit. at period of time t1<t<t2, switching off q1 and switching on q2: the circuit analysis can be illustrated by applying kirshoff’s voltage law as follows: 0=−⋅−−⋅− outll l onl vri dt di lrsi …(2) by defining ∆ as eq. (3), as a switching function to turn vsupply on and off: 21 10 0 1 ttt tt 〈〈 〈〈    =∆ …(3) so the mathematical model (eq. (1) and eq. (2)) can be written in state space representation as follows: let: x1= il, ��� = dt dil , x2=vout , ��� = dt dvout …(4) ��� = �� + ��� … (5) � = ���� ������ ���� = � �(�������)� ����(�������)(������)��(�����) �(������)��(�����)� …(6) = !�!�" = � ∆�∆(������)��(�����)� …(7) � = $0 1' …(8) in this work, the buck converter power circuit specifications at a frequency of 80 khz, which are taken from [3, 4], are listed in table 1. table 1, the parameter values of the buck converter model [3, 4]. description symbol value unit inductance l 47 µh capacitor c 68 µf load resistance loadr 2.345 ω inductor effective series resistance lr 0.13 ω capacitor effective series resistance cr 55 mω the on-n-channel resistance of mos transistors onrs 2.1 ω supply voltage supplyv 3.75 v l 0 vout rload q2 1 2 3 vsupply rl q1 1 2 3 rc 0 c rl khulood e. dagher al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 129140 (2018) 131 3. modified elman neural pid controller design the proposed structure of the closed loop buck converter pid controller based on a modified elman neural network technique is shown in figure (2). fig. 2. the structure of menn-pid controller for buck converter equation model. the on-line tune control action of menn-pid is very essential for stabilizing the error voltage signal of the output of the buck converter system when the actual output voltage is drifting from the desired voltage and to give a high performance evaluation with disturbance rejection. the pid control equation in the time domain form is given by eq. (9) [8, 9]. dt tde ktdtektektu d t ip )( )()()()( 0 ++= ∫ …(9) where: kp is the proportional gain; ki is the integral gain; kd is the derivative gain; u(t) is the control action and e(t) is the error signal. figure 3 shows the new structure of the mennpid controller which is constructed from four layers each of which has its own operation as explained below [10]: • input layer: it works as a buffer i.e. pass the data without any modification. • hidden layer: it is the active layer with the non-linear activation functions. • context layer: it is a memory layer without activation functions. • output layer: it represents a linear collector unit which adds all fed signals. fig. 3. the new structure of menn-pid controller. the network weights notation are: kp, ki, and kd hidden layers weights.vc :context layers weight. li : linear node as scaling factor and it is equal to 1. h : sigmoid nonlinear node. )(kho c : context unit output. )(kh : hidden unit. α : selfconnections feedback gain, which is represented randomly between (0 to 1). β : connection weight from the hidden layer to the context layer and it is represented randomly between (0 and 1). e(k): input error signal. u(k): control action signal. the proposed control law of the menn-pid controller for the buck converter system is as follows: )()( −×= hliku … (10) for the output h(-) of the neural network and it uses a sigmoid activation function as in equation (11) [9]: 1 1 2 )( )( − + =− −− nete h …(11) )(−net is calculated from equations (12) and (13): ))(())1()(( )1()(()((()( khvckekekd kekekikekpnet o c×+−−×+ −−×+×=− …(12) where: )1()1()( −+−= kukhkh o c o c βα … (13) the new proposed menn-pid has considerable properties which can be summarized by : • fast learning, high adaptation performance, and high order control performance due to the context units in menn which memorize the previous activations of the hidden units. desired voltage mennpid controller control parameters e(k) + u(k) buck converter eq. model (k)outv deo tuning controller vc c o h )(ku h α hidden layer h input layer )(ke context layer β l output layer )1()( −− keke )1()( −+ keke kp ki kd )1( −ku z1 khulood e. dagher al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 129140 (2018) 132 • good dynamic characteristic, no output oscillation and strong robustness performance due to the self-connection in the context units which increase the order of the controller model. the near optimal weights of the menn-pid controller kp, ki, kd, and vc will be updated online by using dolphin echolocation optimization algorithm as explained in the next section. 4. dolphin echolocation optimization algorithm dolphin echo optimization is a recent discrete meta-heuristic optimization algorithm developed by ali kaveh [7]. they inspired it from the fact that the dolphins take the advantages of echolocation to discover the environment and hunt prey in nature the probability of dolphin hunting is increased every time till it gets the prey. the deo simulates the process of hunting thus, the algorithm proportionally limits (decreases) the exploration space with respect to the target’s distance by controlling the index of convergence factor cf which is defined as the average probability of the best answer. simply the deo algorithm divides it work into two phases: in the first phase the algorithm performs a global search and this means that the deo explores all around the search space by exploring some random locations and in the second phase, the deo concentrates the search around better results achieved in the first phase i.e. the algorithm goes gradually to the local search in a user defined curve. it is very important to mention here that the probability of getting the near optimal solution is increased in each step ahead till reaching the target [7, 11]. fig. 4. the flowchart of deo. the typical flowchart of the deo algorithm is shown in figure (4) and the steps of the tuning algorithm are as follows: step one “initialization” this step contains the initialization for the following: • random location matrix l with dimension l[-]nlxnv where: nl :number of location; nv number of variable which are kp, ki, kd and vd in the proposed controller design. calculate the accumulative fitness af for the alternatives and its neighborhood according to the deo rule. yes no stop criteria stop initialize the following: probability equation. dolphins random location. calculate the fitness use the probability to choose the next loop location find the best location calculate the probability based on af set the following: best location probability=predefined probability in the current loop distribute the other probability between the other alternatives khulood e. dagher al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 129140 (2018) 133 • alternative matrix with dimension [ma×nv] where ma is maximum alternative number in the search space with ascending order form. • maximum loops number n:number of loops ith in which the algorithm should reach to the target. step two “cf predefining and finding” set pp1 =0.1which represent the convergence factor of the randomly selected location in the first loop then use it to find the predefined probability pp according to the equation (14) [7]: pp(loopi)=pp1+0.1((loopi-1) …(14) step three “fitness calculation” fitness(li)= �()*(+,)� …(15) where . > 0, mse: mean square error of location is mse(li)= �0 ∑ ( 234 − 678)�09:� …(16) step four “accumulated fitness af computation” in this step, the search space (alternative matrix) has to be divided into two regions, including an affected region within the affected radius re and the not affected region. the recommendation says that re is a quadric search space. now: • find the position of the location l(i,j) in the jth column of the alternative and put it in a vector named a. note: in re, the accumulative fitness of the alternative a’s neighbors is affected from its fitness then calculate the af for each jth variable in l(i,j) location by using the dolphin equation given below [7]: �;(� + �)9�� = �;(� + �)9 + <=> =? 0 � < a6b3c �e73f9ghi��(�9)�i a6b3c �e73 < � ≤ a(k, m)f9ghi��(�9)�i0 a(k, m) < � ≤ noo3c �e73� > noo3c �e73 …(17) where: noo3c �e73 = a(k, m) + p3 …(18) a6b3c �e73 = a(k, m) − p3 …(19) a+x<0and a+x>l(aj) (length of aj ) are not valid. step five “best location finding” best location will have best af thus, here terminate algorithm if termination criteria e ≤ esmall is satisfied, else: • find the alternative assigned to the variable of best location • let af for best location alternative=0 step six” probability determination and allocation” • determine the probability as equation (20). p(i,j) = qr,s∑ qr,stuvwxy …(20) • assign probability equals to pp for all variables of the best location (p(i,j)=pp) and p(i,j)=(1-pploopi)p(i,j) step seven “next loop location selection” update location value with respect to the allocated probability of its alternative. step eight “repetition” repeat the steps two to seven till the maximum number of iterations is satisfied. in this work, the steps of the on-line deo algorithm for finding and tuning control parameters of the proposed menn-pid controller are repeated at 3.6 µsecond (sampling time) for each sample based on shannon theorem. 5. matlab simulation results the on-line dolphin echolocation optimization tuning control algorithm for the proposed menn-pid controller is carried out by using the matlab simulation package in order to achieve the reference output voltage for the dc buck converter system. by applying the shanon theorem, the sampling time of the buck converter system is equal to 3.6 µsec based on the time constant of the system which is equal to τ=36.5µsec depending on the natural frequency wn=2.44×10+4 rad/sec and the damping ratio ζ= 1.12 of the buck converter system that have been calculated from eq. (6). figure 5 shows the unit step change open loop response for the output voltage of buck converter system which has stable response. fig. 5. open loop response for output voltage of buck converter system. khulood e. dagher al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 129140 (2018) 134 in this work, to investigate the menn-pid controller as shown in figure 2 with deo tuning control methodology which has a capability of generating optimal voltage control action and minimizing the voltage error with minimum number of fitness evaluation, the parameters of the control methodology based on dolphin algorithm are defined in table 2. the number of locations, variables and values of kp, ki, kd, vc are selected by using try and error method based on best results that have been obtained. table 2, the parameters of deo algorithm. the number of locations nl=25 the number of variables nv=4 the best range values of kp weight kp=[0.1, 0.2, 0.3, 0.4, 0.5, 0.6 to 4] the best range values of ki weight ki=[0.025, 0.05, 0.075, 0.1 to 1] the best range values of kd weight kd=[0.0125, 0.025, 0.0375 to 0.5] the best range values of vc weight vc=[0.075, 0.15, 0.225, 0.3 to 3] the number of alternative matrix length ma=40 the number of loop n= 10 the affected radius re=±10 the minimum error value esmall=0.001 the simulation results of the closed loop voltage control system with the variable step change as (2, 2.5 and 3) volt in the buck converter’s reference output voltage with on-line tuning menn-pid controller with initial output voltage of the system equals to zero volt can be shown in figures (6-a, b, c). the output voltage response of the buck converter system in the variable step change was very small over-shoot in the transient state while at steady-state, the error was equal to zero value in each step change, as shown in figure (6-a) when we compared with another controller results as in [4]. in figure (6-b), the voltage error signal of the closed loop buck converter controller system was a small value in the transient and it has become zero at the steady state. the action response of the menn-pid controller was smooth without oscillation response, no spikes behavior and the action did not reach to the saturation state of 3.75 volt depending on the supply voltage. figure (7) clearly shows the improved performance index of the buck system based on the mean square error (mse) for the on-line tuning dolphin control methodology at 300 samples. figures (8-a, b, c, d) show the parameters of the menn-pid controller kp, ki, kd and vc which have been tuned on-line based on dolphin algorithm at each sample. in this on-line deo algorithm, at sample 80 for example, the accumulative fitness of the kp, ki, kd, vc control gains in the 10th loop or (final loop) of the algorithm can be shown in figure (9a,b,c,d) respectively. (a) (b) (c) fig. 6. simulation results of the adaptive pid controller: (a) output voltage for buck converter model; (b) voltage error; (c) voltage control action. 50 100 150 200 250 300 0 0.5 1 1.5 2 2.5 3 3.5 samples b u c k c o n v e rt e r o u tp u t v o lt a g e (v o lt ) desired output actual output voltage 50 100 150 200 250 300 -0.5 0 0.5 1 1.5 2 samples e r r o r v o lt a g e s ig n a l (v o lt ) 50 100 150 200 250 300 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 samples v o lt a g e c o n tr o l a c ti o n ( v o lt ) khulood e. dagher al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 129140 (2018) 135 fig. 7. on-line performance index (mse). to verify that the closed loop control buck converter system has a robust performance for boundary disturbance through adding variable load resistance by decreasing 10% from its value at sample 100 (0.36 msec), the output voltage response of the buck converter system to a step change 1.75 volt has followed the reference voltage at sample 50 (0.18 msec), the output voltage response of the buck converter system to a step change 1.75 volt is followed the reference voltage at sample 50 (0.18 msec) with no overshoot at transit response and robustness response during adding the disturbance as shown in figure (10-a), the output voltage of the buck converter system did not accessed ±0.05 volt from the reference output voltage and very small overshoot in the transit response then at steady-state response the error voltage signal was equal to zero value. (a) (b) (c) (d) fig. 8. simulation results of the control parameters: (a) kp; (b) ki; (c) kd and (d) vc. the small value of the error voltage signal between the reference voltage and the output voltage of the buck converter system is shown in figure (10-b). figure (10-c) shows the response of the control action which has a fast and strong adaptability with robustness performance because the control parameters are learned and tuned by a powerful on-line dolphin algorithm especially when adding boundary disturbance to show the control action has a capability to track the error voltage signal of the buck converter system to follow the reference voltage as step change and reduce the effect of the load resistance disturbance. 50 100 150 200 250 300 0 1 2 3 4 5 6 7 8 x 10 -3 samples o n -l in e c o st f u n c ti o n m s e 50 100 150 200 250 300 0.8 1 1.2 1.4 1.6 1.8 2 2.2 2.4 2.6 2.8 samples k p c o n tr o l g a in 0 50 100 150 200 250 300 0.05 0.1 0.15 0.2 0.25 samples k i c o n tr o l g a in 50 100 150 200 250 300 0.2 0.25 0.3 0.35 0.4 0.45 0.5 samples k d c o n tr o l g a in 50 100 150 200 250 300 1.15 1.2 1.25 1.3 1.35 1.4 1.45 1.5 1.55 1.6 samples v c c o n tr o l g a in khulood e. dagher al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 129140 (2018) 136 (a) (b) (c) (d) fig. 9. the accumulative fitness of the control gains: a) kp, b) ki, c) kd, d) vc. figure 11 shows the cost function of the online tuning dolphin control algorithm is clearly improved the performance of the proposed menn-pid controller for the buck converter system especially at sample 100 during adding disturbance. the on-line tuning the parameters of the menn-pid controller kp, ki, kd and vc are shown in figures (12-a, b,c, d) respectively which are found and tuned by using deo algorithm in order to find the best voltage control action that depends on the initial parameters of the deo algorithm. 0.5 1 1.5 2 2.5 3 3.5 4 0 100 200 300 400 500 600 700 800 900 alternative of kp control gain a c c u m u la ti v e f it n e ss 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 0 100 200 300 400 500 600 700 800 900 1000 alternative of ki control gain a c cu m u la ti v e f it n es s 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 0 100 200 300 400 500 600 700 800 900 1000 alternative of kd control gain a cc u m u la ti v e f it n es s 0 0.5 1 1.5 2 2.5 3 0 100 200 300 400 500 600 700 800 900 1000 alternative of vc control gain a cc u m u la ti v e f it n e ss khulood e. dagher al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 129140 (2018) 137 (a) (b) (c) fig. 10. simulation results of the menn-pid controller with disturbance effect: (a) output voltage for buck converter model; (b) voltage error; (c) voltage control action. 50 100 150 200 250 300 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 samples v o lt a g e c o n tr o l a c ti o n ( v o lt ) khulood e. dagher al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 129140 (2018) 138 fig. 11. on-line performance index (mse) with disturbance effect. (a) (b) (c) (d) fig. 12. simulation results of the control parameters: (a) kp; (b) ki; (c) kd; (d) vc. 6. conclusions the numerical simulation results of the proposed menn-pid controller based on the deo algorithm is presented in this paper for the dc-dc buck converter system showing the following capabilities: • an on-line optimization was achieved for the control gains of the proposed controller. • a suitable voltage control action was obtained without a saturation voltage state. • tracking an excellent reference voltage with a minimum voltage error was achieved. • strong adaptability performance through changing the desired voltage level output. • high robustness performance when changing the load resistance as the disturbances effect to the back converter system. 7. references [1] s. chander, p. agarwal, i. gupta, “asic and fpga based dpwm architectures for single-phase and single-output dc-dc converter: a review”. central european journal of engineering. vol. 19, no. 4, pp. 620-643, (2013). [2] a. emami, m. poudeh, s. eshtehardiha, “particle swarm optimization for improved performance of pid controller on buck converter”. the international conference of ieee on mechatronics and automation. pp. 520-524, (2008). [3] m. garg, y. hote, m. pathak, “design and performance analysis of a pwm dc-dc buck converter using pi-lead compensator”. 50 100 150 200 250 300 0 1 2 3 4 5 6 x 10 -3 samples o n -l in e c o st f u n c ti o n m s e 50 100 150 200 250 300 0.8 1 1.2 1.4 1.6 1.8 2 2.2 2.4 2.6 2.8 samples k p c o n tr o l g a in 50 100 150 200 250 300 0.08 0.1 0.12 0.14 0.16 0.18 0.2 0.22 0.24 samples k i c o n tr o l g a in 50 100 150 200 250 300 0.04 0.05 0.06 0.07 0.08 0.09 0.1 0.11 samples k d c o n tr o l g a in 0 50 100 150 200 250 300 1.4 1.6 1.8 2 2.2 2.4 2.6 2.8 3 samples v c c o n tr o l g a in khulood e. dagher al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 129140 (2018) 139 arabian journal for science and engineering . vol. 40, no. 12, pp. 3607-3626, (2015). [4] m. tapou, h. al-raweshidy, m. abbod, m. al-kindi, “a buck converter for dvs compatible processors in mobile computing applications using fuzzy logic implemented in a risc based microcontroller”. the 2nd internation conference on circuit and system control signal. prague, czech. pp. 135-139, (2011). [5] k-h kim, b-s kong, y-h jun, “adaptive frequency-controlled ultra-fast hysteretic buck converter for portable devices”. international conference of ieee on soc design. pp. 5-8, (2012). [6] j. chuang, h. chou, “an efficient fast response hysteresis buck converter with adaptive synthetic ripple modulator”. the 8th international conference of ieee on power electronics. pp. 620-627, (2011) [7] a. kaveh and n. farhoudi,”a new optimization method: dolphin echolocation”. advances in engineering software. vol. 59, pp. 53-70, (2013). [8] a. s. al-araji, “development of an on-line self-tuning fpga-pid-pwm control algorithm design for dc-dc buck converter in mobile applications”. engineering journal. vol. 23, no. 8, pp. 84106, (2017). [9] k. e. dagher and a. s. al-araji, ”design of a nonlinear pid neural trajectory tracking controller for mobile robot based on optimization algorithm”. engineering & technology journal vol. 32, no. 4, pp. 973986, (2014). [10] a. s. al-araji, m. f. abbod and h. s. alraweshidy, “design of a neural predictive controller for nonholonomic mobile robot based on posture identifier”. proceedings of the iasted international conference intelligent systems and control (isc 2011), cambridge, united kingdom, pp.198-207, (2011). [11] a. kaveh and n. farhoudi,”dolphin echolocation optimization: continuous search space”. advances in computational design. vol. 1, no. 2, pp. 175-194, (2016). )2018( 123-128، صفحة 3، العدد14دجلة الخوارزمي الهندسية المجلم اسكندر داغرخلود 140 ستمرالمتصميم مسيطر تناسبي تكاملي تفاضلي عصبي ايلمن المعدل لنظام محول خافض التيار مبنيا على أساس أمثلية الدولفين لتحديد الموقع بالصدى خلود اسكندر داغر جامعة بغداد /هندسة الخوارزمي الكلية dagherkhulood@kecbu.uobagdad.edu.iq :البريد االلكتروني الخالصة فض التيار المحول الخا من لنظامباالعتماد على الشبكة العصبية المعدلة ايلإن هذا البحث يصف مقترح جديد لهيكلية المسيطر التناسبي التكاملي التفاضلي بشكل حي بوطة للتنغيمقنية مضتهزة المتنقلة. إن الخوارزمية الدولفين االمثلية لتحديد الموقع بالصدى تعتبر المستمر والذي يستخدم في عمل البطارية لألج ى هائيات الصغرع في النعناصر المسيطر التناسبي التكاملي التفاضلي العصبي ايلمن المعدل بدون الوقوومتصل لذلك تم استخدامها لتنغيم والحصول على لدولفين التي قادت إلى إيجاد أفضل عناصر للمسيطر المقترح تم أخذها من خوارزمية ا إن نتائج المحاكاة أظهرت ان المحلية أثناء تعليم المسيطر المقترح. ،كإضافة إلى ذل لمرغوب.اإلشباع وان هذا الفعل أدى إلى استقرار أداء النظام المحول الخافض للتيار المستمر وتحقيق اإلخراج أفضل فعل وبدون حالة ا .%١٠ب هنالك تقليل لتتابع خطأ إخراج فولتية الى قيمة الصفر لنظام المحول الخافض للتيار المستمر خصوصا عند تغيير ممانعة الحمل موفق ومحمد وفاروق al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 1525 (2013) aeroelastic behavior of a wind turbine blade by a fluid -structure interaction analysis mauwafak a. tawfik* mohammed i. abu-tabikh** farouk o. hamdoon*** *,** department of machines and equipment engineering / university of technology *** department of mechanical engineering / college of engineering / wassit university (received 10 march 2013; accepted 29 may 2013) abstract in this paper, a numerical model for fluid-structure interaction (fsi) analysis is developed for investigating the aeroelastic response of a single wind turbine blade. the blade element momentum (bem) theory was adopted to calculate the aerodynamic forces considering the effects of wind shear and tower shadow. the wind turbine blade was modeled as a rotating cantilever beam discretized using finite element method (fem) to analyze the deformation and vibration of the blade. the aeroelastic response of the blade was obtained by coupling these aerodynamic and structural models using a coupled bem-fem program written in matlab. the governing fsi equations of motion are iteratively calculated at each time step, through exchanging data between the structure and fluid by using a newmark’s implicit time integration scheme. the results obtained from this paper show that the proposed modeling can be used for a quick assessment of the wind turbine blades taking the fluid-structure interaction into account. this modeling can also be a useful tool for the analysis of airplane propeller blades. keywords: wind turbine, aeroelasticity, fsi model, fem, blade element momentum. 1. introduction the interaction between fluids and structures play an important role in a number of fields. important applications can be found in airplane wings, blade machines, tall buildings, suspension bridges and biomechanics (e.g. elastic artery modeling and simulation of flow in blood vessels). the interaction between flowing fluids and vibrating structure is the main subject of the aeroelastisity. the flow induced vibration may affect negatively the operation and the response of the system. aeroelasticty of wind turbine blade is one of main considerations for the design of wind turbine, because aerodynamic loading causes blade to bend mostly in flapwise direction, and causes blade section to twist to create new fluid fields surrounding the blade. this interaction between aerodynamics and deformation of wind turbine blade may lead to twist to create new fluid fields surrounding the blade. this interaction between aerodynamics and deformation of wind turbine blade may lead to aeroelastic problem. in fact, a lot of studies related to the aeroelasticity of wind turbine, widely used computational fluid dynamics (cfd) codes to determine the aerodynamic loading [1, 2 and 3]. these codes require a large numerical time and powerful computers because the solution using these codes may take days to completely converge. on the other hand, using a full 3d model for the blade to compute the structural deformation is computationally too expensive, and hence the blades are treated as series of 1d beam elements in many aeroelastic codes [4]. the aim of this paper is to develop an alternative computationally cheaper and thus fast aeroelastic code for investigating the aeroelastic response of a single wind turbine blade. for this purpose, a simplified numerical modeling for fluid mauwafak a. tawfik al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 1525 (2013) 16 – structure interaction analysis is presented. the bem method is adopted to calculate the aerodynamic forces considering wind shear and tower shadow. structural dynamic modal is developed based on hamilton’s principle combining with fem. the rotating blade is treated as 1d elastic beam subject to flapwise bending and torsion. a computational flow chart for the fully fluid-structure coupling is presented where the governing aeroelastic equations are solved iteratively within each time step. 2. aerodynamic loading model aerodynamic loads acting on a wind turbine blade is modeled based on unsteady bem theory and prandtl’s tip loss factor. this method is very fast and provides accurate results provided that reliable airfoil data are available for the lift, drag and moment coefficients as a function of the angle of attack. 2.1. bem theory the algorithm of unsteady bem theory given in [5,6] is adopted in this work to compute the aerodynamic loads. once unsteady bem algorithm is applied, the tangential py and normal pz distribution of the loads acting on each blade at each radial position, at each time step is computed from lift l and drag d forces resulting from the inflow on the blade using the relative velocity and angle of attack values as follows: = | | ( ) …(1) = | | ( ) …(2) = (∅) − cos (∅) ...(3) = cos(∅) + sin (∅) …(4) also aerodynamic pitching moment about the aerodynamic center is calculated as follows: = | | ( ) …(5) where cl, cd and cm are lift, drag and pitching moment coefficients respectively, obtained from a lookup airfoil data table depending on the angle of attack.figure (1) shows the velocity triangle seen locally on a blade element. the vector representation of relative velocity can be written as: ⃑ = ⃑ + ⃑ + ⃑ − ⃑ …(6) fig. 1. velocity triangle seen locally on a blade element [5]. from the velocity triangle, the angle of attack, α, can be computed if the induced velocity, w and the velocity of the blade section are known: = ∅ − ( + ) …(7) where (β + θp) is the pitch angle plus the twist of the blade at each station, and the flow angle, , is defined as: ∅ = , , …(8) knowing α, the lift, drag and moment coefficients can be looked up in airfoil data table. the equations that are used in unsteady bem model of the present work for normal and tangential induced velocities can be derived from glauert’s relation between thrust and induced velocity [5, 6]. = ∅ | . ( . )| …(9) = ∅ | . ( . )| …(10) where fg refers to as the glauert correction, is an empirical relation between the thrust coefficient and axial induction factor. it is assumed that the induction factor does not exceed 0.2 and hence fg equals 1 [6]. structural deformation for each blade station is used to calculate the velocity of the blade section and hence the relative velocity for each element of the blade of the wind turbine is computed. 2.2. wind profile besides reliable airfoil data for the different blade section, also realistic varying wind field are required as input to an aeroelastic calculation of a wind turbine [5]. wind speed generally increases mauwafak a. tawfik al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 1525 (2013) 17 with height, see figure (2). therefore, a blade pointing upwards would encounter wind speeds greater than a blade pointing downwards. the wind shear is modeled in this work by the widely used power law as [6]: v (x) = v (h) ( ) …(11) exponent v increases with the surface roughness. it is in the range between 0.1 and 0.25 [6]. the distribution of wind is also altered due to the presence of tower. for an upwind turbine, when the blade is directly in front of the tower, it experiences minimum wind. this effect is called tower shadow. a simple model for the influence of the tower is to assume a potential flow around a cylinder of a diameter 2a , see figure (3). the radial and tangential velocity components vθ and vr around the tower are determined by the following equations [6]: = 1 − cos …(12) = − 1 + sin …(13) fig. 2. wind shear model [6]. fig. 3. tower effect model. 3. blade structural model the rotating blade of the wind turbine is modeled as a cantilever elastic bernoulli-euler beam with flapwise and torsion degrees of freedom based on stevens [8]. a pretwist angle θ is adopted in the blade model varying linearly through the span. the corresponding structural dynamic equations are derived based on hamilton’s principle and are then discretized using the finite element with seven degree of freedom beam element. the main coordinate systems which are chosen in the analysis of the blade model are shown in figures (4) and (5). fig. 4. blade coordinate system and elastic deformation [7]. mauwafak a. tawfik al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 1525 (2013) 18 fig. 5. cross section coordinate system figure (4) shows the main coordinate system x, y, z that is fixed in the blade root with its origin in the intersection of blade root cross-section and elastic axis. when the blade is not deformed, the x axis is exactly coincident with elastic axis. the figure also shows the deformed blade and elastic displacement u, v and w in the x, y and z direction, respectively. figure (5) shows an arbitrary blade cross section and its local coordinate system η and ζ. the torsional deflection (ø), due to the blade deformation can also be seen. 3.1. hamilton’s principle the equations of motion for a rotating cantilever, isotropic blade are obtained using hamilton’s principle [8]: ∫ [ ( − ) − ] = 0 …(14) where u is the strain energy, t is the kinetic energy and w is the virtual work of the external forces, where their variation can be expressed as: = ∫ ∬ ( + + ) …(15) = ∫ ∬ . …(16) = ∫ ( + ) …(17) where m is the moment about the elastic axis in the deformed coordinate system and is calculated as follows: = − …(18) where ea is the distance from the elastic axis to the aerodynamic center. 3.2. finite element method the blade is divided into a number of beam elements. each element is a seven degree of freedom with three nodes, two external and one internal, see figure (6) [8]. within each element, deformations between the nodes are described using interpolating polynomials called shape functions. fig. 6. seven dof beam element [8]. a cubic polynomial shape functions is assumed for the flap deformation (w) and a quadratic polynomial shape functions for the torsion deformation (ø). the continuous deflections over a beam element can be expressed in term of nodal displacements: ( )∅( ) = 00 ∅ { } …(19) where = / is the length of ith beam element, and {u}, the element nodal displacement vector is defined as: { } = , ′ , , ′ ,∅ ,∅ ,∅ …(20) the interpolating functions are defined as: = = ⎩⎪⎨ ⎪⎧ 2 − 3 + 1 ( − 2 + )−2 3 + 3 2 ( 3 − 2) ⎭⎪⎬ ⎪⎫ …(21) ∅ = ∅ ∅ ∅ = 2 − 3 + 1−4 + 4 2 2 − …(22) mauwafak a. tawfik al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 1525 (2013) 19 application of hamilton’s principle in the discritized form and performing the necessary calculus and assembling, the following nonlinear equation of motion for rotating blade can be obtained: [ ]{ ̈ } + [c] { ̇ }+[k]{u}={q} …(23) where [m], [c], and [k] are global matrices of inertia, damping and stiffness respectively, {q} is the aerodynamic load vector. the structural damping effect was introduced into the model using the rayleigh approach. the formula for the rayleigh damping matrix is characterized by the following equation: [c]= a [m] + b [k] …(24) where a and b coefficients are computed using two characteristic system eigenfrequencies ω1, ω2 and their desired damping ratio ζ1, ζ2. 4. fully coupled bem-fem approach the system of fsi equations of motion (23) of wind turbine blade are solved by a numerical newmark’s time integration scheme. assuming a linear variation of the acceleration between two instants of time, the expressions for velocity and displacements are given by: ̇ ∆ = ̇ + [(1 − ) ̈ + ̈ ∆ ]∆ …(25) ∆ = + ̇ ∆ + [ − ̈ + ̈ ∆ ]∆ …(26) in which γ and β are newmark’s parameters that are chosen based on desired stability and accuracy. the task is to evaluate the displacement, velocity and acceleration at the time t+δt . after the displacement increment δu is introduced to solve the fsi equations of motion, the following expressions for ̈ ∆ , ̇ ∆ , ∆ are formulated as a function of ̈ , ̇ , . ̈ ∆ = ∆ ∆ − ∆ ̇ − ( − 1) ̈ …(27) ̇ ∆ = ∆ ∆ − − 1 ̇ ∆ − 1 ̈ …(28) ∆ = + ∆ …(29) in this work, the aero elastic response of the wind turbine blade was conducted using a coupled bem-fem program written in matlab. assuming initial values for displacement, velocity and acceleration vectors; the program first calculates the aerodynamic force vector {q} for the blade based on bem theory. then at each time step, the aerodynamic forces are applied on the corresponding nodes of the blade and the program solves the structural equation based on fem to determine the new blade deformations at time t+δt using equations (27)-(29). lastly, due to these new deformations the program updates the aerodynamic forces for the next time step t+δt . the flow chart of the fully fluid – structure interaction coupling approach is shown in figure (7). 5. numerical results the present work is to study a single wind turbine blade’s aeroelastic response in time domain. the combined flap torsion oscillation is presented here. a 2mw tjaerborg wind turbine blade was chosen to perform the numerical simulation using a fully coupled fsi analysis. the detailed structural blade properties and airfoil data are well documented in [6] and [9] respectively. the blade is originally twisted and thus structural properties were modified into the main blade coordinate system [6]. some basic parameters and geometry of this turbine are listed in table (1). the 29 m blade is composed a series of naca 4412-4443 profile and is discretized by 29 elements. the simulation is performed at a constant wind speed at hub vh=12 m/s, air density is 1.225 kg/m3, wind speed exponent ν is 0.2 and the diameter of the tower is assumed to be constant with 4.5 m. the rotating speed of rotor is fairly constant speed of 20 rpm. based on this information the blade will make one complete revolution and passes the tower every 3 seconds. the desired damping ratio ζ1=ζ2=0.02 and the time step is chosen to be δt =0.0003. the simulation first was performed assuming the blade is rigid. figure (8) shows the time history of angle of attack and lift coefficient of the blade at three different radial nodes. the graphs show several dips. each dip corresponds to the instant that the blade passes the tower. then, fsi simulation considering flexible blade has been performed. figure (9) shows the time history of the flapwise displacement at three different radial nodes. maximum deformation is at free end of the blade, is 2.3 m (7.93 % of blade mauwafak a. tawfik al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 1525 (2013) 20 length). this result agrees with the hypothesis introduced in spera [10] which states that the linear formulation is adequate with small deformation where the deflection ratio is less than 10%. figure (10) shows the time history of torsion angle at three different cross sections. the torsion angle increases with distance from the root to tip and the torsion angle undergoes high frequency oscillations. this behavior agrees qualitatively with that obtained from [1]. figures (9) and (10) show that once the initial transient decays, there is a sudden decrease in the flapwise displacement and torsion angle at each time corresponds to the blade passes the tower. figure (11) shows the time history of angle of attack and lift coefficient at three different nodes. the transient dynamic effect and unsmooth curves can be seen compared with rigid blade simulation result in figure (8). it is obvious that the outer section of the blade is highly affected by the interaction between wind load and structural vibration due to its low stiffness, in comparison with the root and middle sections which are designed to have high stiffness. elastic deformation of blade initial values start next time step structural dynamic calculation aerodynamic load calculation wind load end yes no fig. 7. flow chart of the fully fsi coupling algorithm. mauwafak a. tawfik al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 1525 (2013) 21 table 1, basic parameters and geometry of the 2mw tjareborg turbine [9]. rotor blades tower number of blades 3 blade length 29 m tower height 56 m rotor diameter 61.1 m root chord 3.3 m shape, upper half conical hub height 61 m tip chord 0.9 m diameter at base 7.25 m rotor speed at rated power 22.36 rpm twist (linear) 0.333 deg./m diameter at h=28 m 4.75 m tilt 3 deg. blade profiles naca 4412 4443 diameter at h=56 m 4.25 m (a) angle of attacks. (b) lift coefficients. fig. 8. time history of (a) angle of attacks and (b) lift coefficients for rigid blade computations. 1 2 3 4 5 6 7 8 9 10 11 12 4 5 6 7 8 9 10 time (sec.) a ng le o f a tta ck (d eg .) r =27m r =21m r =12m 1 2 3 4 5 6 7 8 9 10 11 12 0.8 0.9 1 1.1 1.2 1.3 1.4 1.5 time (sec.) li ft co ef fic ie nt r = 27m r = 21m r = 12m mauwafak a. tawfik al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 1525 (2013) 22 fig. 9. time history of flapwise displacement at three different nodes along the blade radial axis. fig. 10. time history of torsional angle for three different nodes along the blade radial axis. (a) angle of attacks. 0 2 4 6 8 10 12 -0.5 0 0.5 1 1.5 2 2.5 interaction time (sec.) fl ap w is e di sp la ce m en t ( m ) r =29m r =21m r =12m 0 2 4 6 8 10 12 -0.8 -0.7 -0.6 -0.5 -0.4 -0.3 -0.2 -0.1 0 interaction time (sec.) to rs io na l a ng le (d eg .) r = 29 m r = 21m r =12 m 1 2 3 4 5 6 7 8 9 10 11 12 4 5 6 7 8 9 10 interaction time (sec.) a ng le o f a tta ck (d eg .) r =27m r = 21m r = 12m mauwafak a. tawfik al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 1525 (2013) 23 (b) lift coefficients. fig. 11. time history of (a) angle of attacks and (b) lift coefficients for flexible blade , fsi computations. 6. conclusion this paper presents a fully fluid-structure interaction (fsi) modeling to solve the aeroelastic problem of a single wind turbine blade. effects of wind shear and tower shadow are considered in this modeling. an effective and fast coupled bem fem program written in matlab is developed for studying the aeroelastic behavior of the blade in time domain using newmark’s time integration scheme. the main conclusions of this paper are listed below: • the results clearly show that the blade section exhibits rotation as well as flapwise deformation and stabilize after several time interactions. • the results show that the aerodynamic loads are highly affected by the flexibility of the blade which will have some effects upon the output power. • the results indicate that the blade passing the tower produces an appreciable drop in the aeroelastic response. • it is concluded that the present modal is computationally more time efficient than other cfd aeroelastic model. • the present fsi modeling is useful and can be utilized in modeling airplane propeller blades nomenclature a radius of tower [m] b number of blades cl lift coefficient cd drag coefficient cm pitching moment coefficient c length of chord [m] d drag force [n] e modulus of elasticity [n/m2] f prandtl’s tip loss correction fg glauert correction g modulus of rigidity [n/m2] h hub height [m], shape function l lift force [n] m moment [n.m] n normal vector; number of blades r blade length [m] r radial position [m] ⃑ blade velocity vector ⃑ undisturbed wind velocity vector ⃑ rotational velocity vector ⃑ relative velocity vector 1 2 3 4 5 6 7 8 9 10 11 12 0.8 0.9 1 1.1 1.2 1.3 1.4 1.5 interaction time (sec.) li ft co ef fic ie nt r = 27m r = 21m r = 12m mauwafak a. tawfik al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 1525 (2013) 24 ⃑ induced velocity vector w flap deformation [m] x distance from surface [m] α angle of attack [deg.] β newmark’s parameter γ newmark’s parameter strain ζ damping ratio θ pretwist blade angle [deg.] v wind profile exponent ρ density of air [kg/m3] flow angle [deg.] , torsional deformation [deg.] 7. references [1] y.bazilevs, m.c.hsu,j .kiendl, r. wuchner and k. u. bletzinger,”3d simulation of wind turbine rotors at full scale. part ii: fluidstructure interaction modeling with composite blades” international journal for numerical methods in fluids, vol.65, pp.236253, 2011. [2] dong h. k. and yoo h. k., ”performance prediction of a 5mw wind turbine considering aeroelastic effect” world academy of science, engineering of technology, vol. (81), pp.771-775, 2011. [3] shuhe w., liaojun z. and yizhi y. “research on aeroelasticity of horizontal axis wind turbines by a fluid-structure coupling numerical method” ieee conference publications, pp.1-5,2009. [4] macolm d. j.,laird d. l., ”modeling of blades as equivalent beams for aeroelastic analysis,” proceedings of aiaa/asme. wind energy symposium. reno, usa, pp.293-303, 2003. [5] m. o .l. hanson, j. n. sorensen, s. voutsinas, n. sorensen and h .aa. madsen, ”state of art in wind turbine aerodynamics and aero-elasticity” progress in aerospace sciences,vol.42,pp.285-330,2006. [6] martin o. l. hanson, ” aerodynamics of wind turbines,” second edition, earthscan, uk, 2008. [7] hodges d. h. and dowel e.h., ”nonlinear equation of motion for elastic bending and torsion of twisted non-uniform blades” nasa tnd-7818, 1974. [8] patricia l. s. ,”active interrogation of helicopter main rotor faults using trailing edge flap actuation” ph.d. thesis, the pennsylvania state university,2001. [9] tjaerborg wind turbine ‘esbjerg’, “geometric and operational data http://130.226.17.201/extra/web_docs/tjare/v k-184-901130.pdf. [10] spera d.a.,”wind turbine technology: fundamental concepts of wind turbine engineering”, 2nd edition, asme press, new york, 1995. http://130.226.17.201/extra/web_docs/tjare/v )2013( 1525 ، صفحة3، العدد9مجلة الخوارزمي الھندسیة المجلد موفق علي توفیق 25 بین المائع التام تحلیل سلوك المرونھ الھوائیھ لشفرة توربین ریاح بأستخدام نموذج للتداخل والھیكل **فاروق عمر حمدون **محمد أدریس أبو طبیخ * موفق علي توفیق ةالجامعھ التكنولوجی/ قسم ھندسة المكائن والمعدات ** ،* جامعة واسط/ ة كلیة الھندس/ قسم الھندسھ المیكانیكیة ** الخالصة .ئع والھیكلیتناول البحث الحالي تحلیال لسلوك المرونھ الھوائیھ لشفرة توربین ریاح من خالل بناء نموذج عددي یعتمد مبدأ التداخل التام بین الما كما تم تمثیل . الشفره في حساب األحمال األیرودینامیھ المؤثره على شفرة توربین الریاح تحت تأثیر القص ووجود البرج أستخدمت طریقة زخم عنصر تمت دراسة أستجابھ المرونھ الھوائیھ للشفره من خالل بناء . في حساب االھتزازات الناتجھ الشفره بعتبھ كابولیھ دواره بأستخدام طریقة العناصر المحدده كل بأستخدام الماتالب یربط بین النموذج الریاضي للقوى األیرودینامیھ ونموذج أھتزاز الھیكل من خالل تبادل البیانات بین النموذجین عند برنامج حاسوبي یة أستخدام النموذج أظھرت النتائج المستحصلھ أمكان. لمعادالت الحركھ للتكامل الزمني) newmark(خطوه زمنیھ بصوره تكراریھ و بأستخدام طریقة األستفاده من النموذج الحالي في تحلیل المرونھ كما یمكن. المقترح في أجراء تقییم سریع لشفرات توربین الریاح تحت تأثیر التداخل بین المائع والھیكل . شفرات الطائرات المروحیھالھوائیھ ل al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 123 (2014) cam dynamic synthesis florian ion t. petrescu* relly victoria v. petrescu** *department of theory of mechanisms and robots / polytechnic university of bucharest / romania / europe ** department of transport, traffic & logistic department / polytechnic university of bucharest/ romania / europe *e-mail: petrescuflorian@yahoo.com **e-mail: petrescuvictoria@yahoo.com (received 10 october 2013; accepted 4 february 2014) abstract the paper presents an original method to make the geometric synthesis of the rotary cam and translated tappet with roll. classical method uses to the geometric synthesis and the reduced tappet velocity, and in this mode the geometric classic method become a geometric and kinematic synthesis method. the new geometric synthesis method uses just the geometric parameters (without velocities), but one utilizes and a condition to realize at the tapped the velocities predicted by the tapped movement laws imposed by the cam profile. then, it makes the dynamic analyze for the imposed cam profile, and one modify the cam profile geometric parameters to determine a good dynamic response (functionality). in this mode it realizes the dynamic synthesis of the cam, and we obtain a normal functionality. keywords: geometric synthesis, dynamic synthesis, rotary cam, translated tappet with roll. 1. introduction in conditions which started to magnetic motors, oil fuel is decreasing, energy which was obtained by burning oil is replaced with nuclear energy, hydropower, solar energy, wind, and other types of unconventional energy, in the conditions in which electric motors have been instead of internal combustion in public transport, but more recently they have entered in the cars world (honda has produced a vehicle that uses a compact electric motor and electricity consumed by the battery is restored by a system that uses an electric generator with hydrogen combustion in cells, so we have a car that burns hydrogen, but has an electric motor), which is the role and prospects which have internal combustion engines type otto or diesel? internal combustion engines in four-stroke (otto, diesel) are robust, dynamic, compact, powerful, reliable, economic, autonomous, independent and will be increasingly clean. let's look at just remember that any electric motor that destroy ozone in the atmosphere needed our planet by sparks emitted by collecting brushes. immediate consequence is that if we only use electric motors in all sectors, we’ll have problems with higher ozone shield that protects our planet and without which no life could exist on earth. magnetic motors (combined with the electromagnetic) are just in the beginning, but they offer us a good perspective, especially in the aeronautics industry. probably at the beginning they will not be used to act as a direct transmission, but will generate electricity that will fill the battery that will actually feed the engine (probably an electric motor). the otto engines or those with internal combustion in general, will have to adapt to hydrogen fuel. it is composed of the basic (hydrogen) can extract industrially, practically from any item (or florian ion t. petrescu al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 123 (2014) 2 combination) through nuclear, chemical, photonic by radiation, by burning, etc... (most easily hydrogen can be extracted from water by breaking up into constituent elements, hydrogen and oxygen; by burning hydrogen one obtains water again that restores a circuit in nature, with no losses and no pollution). hydrogen must be stored in reservoirs cell (a honeycomb) for there is no danger of explosion; the best would be if we could breaking up water directly on the vehicle, in which case the reservoir would feed water (and there were announced some successful). as a backup, there are trees that can donate a fuel oil, which could be planted on the extended zone, or directly in the consumer court. with many years ago, professor melvin calvin, (berkeley university), discovered that “euphora” tree, a rare species, contained in its trunk a liquid that has the same characteristics as raw oil. the same professor discovered on the territory of brazil, a tree which contains in its trunk a fuel with properties similar to diesel. during a journey in brazil, the natives driven him (professor calvin) to a tree called by them "copa-iba". at the time of boring the tree trunk, from it to begin flow a gold liquid, which was used as indigenous raw material base for the preparation of perfumes or, in concentrated form, as a balm. nobody see that it is a pure fuel that can be used directly by diesel engines. calvin said that after he poured the liquid extracted from the tree trunk directly into the tank of his car (equipped with a diesel), engine functioned irreproachable. in brazil the tree is fairly widespread. it could be adapted in other areas of the world, planted in the forests, and the courts of people. from a jagged tree is filled about half of the tank; one covers the slash and it is not open until after six months; it means that having 12 trees in a courtyard, a man can fill monthly a tank with the new natural diesel fuel. in some countries (usa, brazil, germany) producing alcohol or vegetable oils, for their use as fuel. in the future, aircraft will use ion engines, magnetic, laser or various micro particles accelerated. now, and the life of the jet engine begin to end. even in these conditions internal combustion engines will be maintained in land vehicles (at least), for power, reliability and especially their dynamics. thermal engine efficiency is still low and, about one third of the engine power is lost just by the distribution mechanism. mechanical efficiency of cam mechanisms was about 4-8%. in the past 20 years, managed to increase to about 14-18%, and now is the time to pick it up again at up to 60%. this is the main objective of this paper. 2. presenting a dynamic model, with one grade of freedom, with variable internal amortization 2.1. determining the amortization coefficient of the mechanism starting with the kinematical schema of the classical valve gear mechanism (see the figure 1), one creates the translating dynamic model, with a single degree of freedom (with a single mass), with variable internal amortization (see the figure 2), having the motion equation (1) [3, 13]. the formula (1) is just a newton equation, where the sum of forces on a single element is 0. 0)( fxcxkxykxm   …(1) 5  1 2 3 4 a b c d c0 o fig. 1. the kinematical schema of the classical valve gear mechanism. the newton equation (1) can be written in the form (2). )()( 0 xkfxykxcxm   …(2) florian ion t. petrescu al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 123 (2014) 3 m m k kx f f(t) c . cx xx(t) k(y-x) k y(t)  camã fig. 2. dynamic model with a single liberty, with variable internal amortization. the differential equation, lagrange, can be written in the form (3). rm ffx dt dm xm   2 1 …(3) comparing the two equations, (2 and 3), one identifies the coefficients and one obtains the resistant force (4), the motor force (5) and the coefficient of internal amortization (6). one can see that the internal amortization coefficient, c, is a variable. )( 000 xxkxkxkxkffr  …(4) )()( xskxykfm  …(5) dt dm c  2 1 …(6) one places the variable coefficient, c, (see the relation 6), in the newton equation (form 1 or 2) and obtains the equation (7). 0)( 2 1 fykxkkx dt dm xm   …(7) the reduced mass can be written in the form (8), (the reduced mass of the system, reduced at the valve). 24 4 21 1 22 325 )()( )()( x j x j x y mmmm       …(8) with the following notations: m2 =the mass of the tappet (of the valve lifter); m3 =the mass of the valve push rod; m5 =the valve mass; j1 =the inertia mechanical moment of the cam; j4 =the inertia mechanical moment of the valve rocker; 2y =the tappet velocity, or the second movement-low, imposed by the cam’s profile; x =the real (dynamic) valve velocity. if one notes with i=i25, the ratio of transmission tappet-valve, given from the valve rocker, the theoretically velocity of the valve, y , (the tappet velocity reduced at the valve), takes the form (9), where the ratio of transmission, i, is given from the formula (10). i y yy 2 5    …(9) dc cc i 0 0 …(10) one can write the following relations (11-16), where y’ is the reduced velocity forced at the tappet by the cam’s profile. with the relations (10, 13, 14, 16) the reduced mass (8), can be written in the forms (17–19). '1 xx  …(11) ''2 1 xx  …(12) '1 ' 212 yiyy   …(13) ' 1 '1 11 xxx       …(14) dc y dc cc cc y cc iy cc y cc y 0 1 0 0 0 1 0 1 0 ' 21 0 2 4 '' '.              …(15) ' '1 ' ' 010 14 x y dcxdc y x        ..(16) 2 0 4 2 1 2 325 ) ' '1 () ' 1 ( ) ' ' ()( x y dc j x j x yi mmmm     …(17) 2 1 2 2 0 4 32 2 5 ) ' 1 () ' ' (] )( )([ x j x y dc j mmimm   …(18) 2 1 2 5 ) ' 1 () ' ' (* x j x y mmm  ..(19) florian ion t. petrescu al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 123 (2014) 4 it derives dm/d and obtains the relations (20– 22). ) ' '' ' '' () ' ' (2) ' ' ''''( ' '2 ' )''''''( ' '2 ]) ' ' [( 2 2 2 2 x x y y x y x y xy x y x yxxy x y d x y d          ...(20) 32 2 ' '' 2 ' '' ' 2 ]) ' 1 [( x x x x xd x d     …(21) 31 2 ' '' 2) ' '' ' '' () ' ' (*2 x x j x x y y x y m d dm   ...(22) the relation (6) can be written in form (23) and with relation (22), it’s taking the forms (24–25).   d dm c  2 …(23) } ' '' ) ' '' ' '' () ' ' ( ] )( )({[ 31 2 2 0 4 32 2 x x j x x y y x y dc j mmic    …(24) ] ' '' ) ' '' ' '' () ' ' (*[ 31 2 x x j x x y y x y mc  …(25) with the notation (26): 2 0 4 32 2 )( )(* dc j mmim  …(26) 2.2. determining the movement equations with the relations (19, 12, 25, 11) the equation (2) take the forms (27, 28, 29, 30 and 31) [13]: 0 2 )(''' fykxkkxcxm   …(27) 03 '' 1 2' ' '' ' '' 2*'22''2 '1 ''2*2 5 ''2 )( ' )() ' ' () 1 ( ) ' ' ( fykxkk x x jx x x y y x y mxx x j x x y mmx       …(28) 0 *2 2*22*2 5 2 )( ' ' '' '') ' ' () ' ' ('''' fykxkk x y ym x x y m x y xmxm     …(29) 0 ''*2'' 5 2 ' ' )( fky x y ymxkkxm   …(30) 0 * 5 2 )() ' ' ''''( fykxkk x y ymxm  …(31) the exact equation (31) can be approximated at the form (32) with x’y’. 0 * 5 2 )()''''( fykxkkymxm  …(32) with the following notations: y=s, y’=s’, y’’=s’’, y’’’=s’’’, the equation (32) takes the approximate form (33) and the complete equation (31) takes the exact form (34). 0 * 5 2 )()''''( fskxkksmxm  …(33) 05 2 )() ' ' ''*''( fskxkk x s smxm  …(34) solving the differential equation by direct integration and obtaining the mother equation one integrates the equation (31) directly. one prepares the equation (31) for the integration. first, one writes (31) in form (35) [13]. i iii tii s x yym xm xkykxkk    2* 2* 0)(   …(35) the equation (35), can be amplified by x’ and one obtains the relation (36). iii t iii s iii yymxxm xxkxykxxkk   2*2* 0)(  …(36) florian ion t. petrescu al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 123 (2014) 5 now, one replaces the term k.y.x’ with iy kk k yk    , (taken in calculation the statically assumption, fm=fr) and one obtains the form (37). iii t iii s iii yymxxm xxkyy kk k xxkk     2*2* 0 2 )(  …(37) one integrates directly the equation (37) and one obtains the mother equation (38). c y m x m xxk y kk kx kk ts     2 ' 2 ' 22 )( 2 2* 2 2* 0 222  …(38) with the initial condition, at the =0, y=y’=0 and x=x’=0, one obtains for the constant of integration, c the value 0. in this case the equation (38), takes the form (39). 2 ' 2 ' 22 )( 2 2* 2 2* 0 222 y m x m xxk y kk kx kk ts      …(39) the equation (39) can be put in the form (40), if one divides it with the 2 kk   . 0 )( ' '2 2 2 2 2 2* 2 2* 02              y kk k y kk m x kk m x kk xk x t s   …(40) the mother equation (40), take the form (41), if one notes: '' y kk k x    , (the static assumption, fm=fr). 0' )( )( )( 2 22 ** 2 2 2 2 2 02            y kk mm kk k y kk k x kk xk x ts  …(41) solving the mother equation (41) directly the equation (41) is a two degree equation in x; one determines directly,  (42-43) and x1,2 (44) [13]. 22 * 2 2 * 2 22 0 ' )( )( )( )()( y kk m kk k m kk skxk ts        …(42) 22 * 2 2 * 2 22 0 )'( )( )( )( )()( ds kk m kk k m kk kskx ts        …(43)     kk xk x 0 2,1 …(44) physically, just the positive solution is valid (see the relation 45). kk xk x    0 …(45) solving the mother equation (41) with finished differences one can solve the mother equation (41) using the finished differences [13]. one notes: xsx  …(46) with the notation (46) placed in the mother equation (41), it obtains the equation (47). 0' )( )( )( 222)( 22 ** 2 2 2 2 2 0022               y kk mm kk k s kk k x kk xk s kk xk xsxs ts  …(47) the equation (47) is a two degree equation in x, which can be solved directly with  (49) and x1,2, (50), or transformed in a single degree equation in x, with (x) 2 0, solved by the relation (48). florian ion t. petrescu al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 123 (2014) 6 20 22** 2 0 22 )()(2 )'(])([)(2)2( )1( kk kk xk s dsmkkm kk k skkkxskkk x ts          …(48) 2 22** 2 2 0 222 )( )'(])([ kk dsmkkm kk k xksk ts       …(49) )( 0 kk xk sx    …(50) 2.3. mechanism with rotary cam and translated tappet with roll first, one presents an original method to determine the efficiency at the mechanism with rotary cam and translated follower with roll [5]. with this occasion it presents and the forces and the velocities as well (figure 3). the pressure angle  (figure 3), is determined by relations (1.5-1.6). we can write the next forces, speeds and powers (1.13-1.18). fm (vm) is perpendicular to the vector ra at a. fm is divided into fa (the sliding force) and fn (the normal force). fn is divided too, into fi (the bending force) and fu (the useful force). the momentary dynamic efficiency can be obtained from relation (1.18). 0 a  a b    a- fn, vn fm, vm fa, va fi, vifn, vn fu, v2 b b0 a0 a o x e s0 rb r0 ra rb s n c rb fig. 3. forces and velocities at the cam with translated follower with roll. the written relations are the following. 2 0 22 b s)(ser  ... (1.1) 2 bb rr  ...(1.2) b b r e   sincos ...(1.3) b b r ss   0cossin  ...(1.4) 22 0 0 )'()( cos esss ss    ...(1.5) 22 0 )'()( ' sin esss es    ...(1.6)  sinsincoscos)cos(  ...(1.7)       )cos(2 )cos()sin( 222 2 0 22   bbbba bba rrrrr rssrer ...(1.8)             a b a a b a r re esssr esressse    sin cos )'()( )'()'()( cos 22 0 22 0 ...(1.9)             a b a a b a r rss esssr resssss    cos sin )'()( ])'()([)( sin 0 22 0 22 00 ...(1.10)              cos ' )cos( )'()( ')( )cos( 22 0 0 a a a a r s esssr sss ...(1.11)  2cos ' cos)cos(  a a r s ...(1.12)      )sin( )sin(   ama ama ff vv ...(1.13) florian ion t. petrescu al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 123 (2014) 7      )cos( )cos(   amn amn ff vv ...(1.14)        sin sin ni ni ff vv ...(1.15)        cos)cos(cos cos)cos(cos2 amnu amn fff vvv ...(1.16)      mmc ammuu vfp vfvfp  22 2 cos)(cos ...(1.17)                    4 2 2 222 22 cos ' ]cos ' []cos)[cos( cos)(cos a i a ai mm amm c u i r s r s vf vf p p ...(1.18) bb rrr  00 …(1.19) 22 0 0 ers b  …(1.20) 0 0cos br e  …(1.21) 0 0 0sin br s  …(1.22) 2.4. the relations to design the profile now one determines the profile of the cam (relations 1.23-1.28). 0  a …(1.23) 00 sinsincoscoscos   aa …(1.24) 00 sincoscossinsin   aa …(1.25)  a …(1.26)  sinsincoscoscos a …(1.27)  cossincossinsin a …(1.28) 2.5. the exact kinematics of b module from the triangle ocb (fig. 3) the length rb (ob) and the complementary angles b (cob) and  (cbo) are determined by the relation (1.11.4). from the general triangle oab, where one knows ob, ab, and the angle between them, b (abo, which is the sum of  with ), the length oa and the angle  (aob) can be determined with the relations (1.7-1.8, 1.29-1.31): ba bba rr rrr    2 cos 222  …(1.29)  cossincossin)sin(  ...(1.30) )sin(sin   a b r r …(1.31) with b and  we can deduce now a and a (the relations 1.32-1.33):   ba …(1.32)    ba …(1.33) from (1.3) one obtains b (1.37), (see 1.341.37) where br (1.36) can be deduced from (1.1). then, (1.38) will be obtained from (1.29): 2 sin b b bb r re      …(1.34) 2 0 )( b bb b rss rre      …(1.35)       sssrr sssrr bb bb   )( )(22 0 0 …(1.36) 22 0 0 )( )( bb b r se rss ssse        … (1.37)      bbaaba baba rrrrrr rrrr   22sin2 cos2cos2   …(1.38) from (1.38) one writes  (1.43), but it is necessary to obtain first ar (1.39) from expression (1.8): florian ion t. petrescu al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 123 (2014) 8       )()sin(2 )cos(222     bb bbbbaa rr rrrrrr …(1.39) to solve (1.39) we need the derivatives  (1.40 and 1.41) and  (1.42). 22 0 0 )'()( )'(')('' ' esss essess    …(1.40)   ' …(1.41) 2 b b r se      …(1.42) now we can determine  (1.43), a (1.33) and a  (1.44):    sin coscos    ba bbaababa rr rrrrrrrr   …(1.43) aa    …(1.44) we write cos a and sin a (1.9-1.10): further, we can obtain the expression cos(a) (1.11), and cos(a-).cos (1.12). finally the forces and the velocities are deduced as follows (1.13-1.16): 2.6. determining the efficiency of the module b with the relationships (1.17-1.18) we can determine the powers and the momentary mechanical efficiency [14]. determining the (dynamic) transmission function d, for the module b the follower’s velocity (1.16) can be written into the form (1.45).              22 22 2 cos'cos' cos ' cos ' cos)cos(cos ss r s r r s v vvv i aa a aa a m amn   …(1.45) with the relationships (1.45) and (1.46) we determine the transmission function (the dynamic modulus), d (1.47):  dsv '2 …(1.46)  2cos i ad …(1.47) expression cos 2  is known (1.48): 22 0 2 02 )'()( )( cos esss ss    …(1.48) the expression of the ’a (1.49) is more difficult.                        ]}')[(2 )'()( ])/{[( /])'()/[(]})'( )()'(')(''[ )'()(])'( ){[(])'()( ')[( 22 0 22 0 222 0 22 0 2 2 00 22 0 2 2 0 22 0 22 0 seessr esss ress essses ssesssssr essses ssesss rseess b b b b i a …(1.49) we will determine  by its expressions (1.501.51):                    22 0 22 0 22 0 22 0 22 0 )'()( ]')[( )'()( )'()(])[( cos esssrr seessr esssrr esssess ba b ba  …(1.50) 22 0 0 )'()( ')( sin esssrr sssr ba b    …(1.51) florian ion t. petrescu al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 123 (2014) 9 the dynamics of distribution mechanisms with translated follower with roll for the dynamics of the module b the relationships (49-50) are used in the forms (1.521.54), where d is determined from (1.47). ][2 ' ] )( [ 2 )( 2 0 2 2** 2 2 02 2 2 kk kx s y kk mm kk k s kk kx s kk kkk x ts              …(1.52) ][2 )'( ] )( [ 2 )( 2 0 2 2** 2 2 02 2 2 kk kx s sd kk mm kk k s kk kx s kk kkk x ts              …(1.53) xsx  …(1.54) 2.7. the dynamic analysis of the module b it presents now the dynamics of the module b for some known movement laws. we begin with the classical law sin (see the diagram in figure 4); a speed rotation n=5500 [rot/min], for a maxim theoretical displacement of the valve h=6 [mm] is used. the phase angle is u=c=65 [degree]; the ray of the basic circle is r0=13 [mm]. for the ray of the roll the value rb=13 [mm] has been adopted. fig. 4. the dynamic analysis of the module b. the law sin, n=550 rpm, u=65 0 , r0=13 [mm], rb=13 [mm], ht=6 [mm], e=0 [mm],k=30 [n/mm], and x0=20 [mm]. fig. 5. the profile sin at the module b. n=5500 rpm u=65 0 , r0=13 [mm], rb=13 [mm], ht=6 [mm]. the dynamics are better than for the classical module c. for a phase angle of just 65 degrees the accelerations have the same values as for the classical module c for a relaxed phase (75 0 -80 0 ). in figure 5 we can see the cam’s profile. it uses the profile sin, a rotation speed n=5500 rpm, and u=65 0 , r0=13 [mm], rb=13 [mm], ht=6 [mm]. the law cos can be seen in the figures 6 and 7. in the figure 6 is presented the dynamic analyze of the profile cos, and its profile design can be seen in the figure 7. the principal parameters are: law cos, n=5500 rpm, u=65 0 , r0=13 [mm], rb=6 [mm], ht=6 [mm], =10.5%. fig. 6. the dynamic analysis of the module b. law cos, n=5500 rpm, u=65 0 , r0=13 [mm], rb=6 [mm], ht=6 [mm], =10.5%. florian ion t. petrescu al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 123 (2014) 10 fig. 7. the profile cos at the module b, n=5500 rpm, u=65 0 , r0=13 [mm], rb=6 [mm], ht=6 [mm]. fig. 8. the dynamic analysis. law c4p1-0, n=5500 rpm, u=80 0 , r0=13 [mm], rb=6 [mm], ht=6 [mm]. in the figure 8 the law c4p, created by the author, is analyzed dynamic. the vibrations are diminished, the noises are limited, the effective displacement of the valve is increased, smax=5.37 [mm]. fig. 9. the profile c4p of the module b. the efficiency has a good value =8.6%. in the figure 9 the profile of c4p law is presented. it starts at the law c4p with n=5500 [rpm], but for this law the rotation velocity can increase to high values of 30000-40000 [rpm] (see the figure 10). fig. 10. the dynamic analysis of the module b. law c4p1-5, n=40000 rpm. florian ion t. petrescu al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 123 (2014) 11 2.8. the new cam synthesis the rotary cam with translated follower with roll (figure 3 or 13), is synthesized dynamic by the new next relationships. it has exchanged the rotation sense from the figure 1 to figure 11, from the clockwise to the counter-clockwise. first, one determines the mass moment of inertia (mechanical) of the mechanism, reduced to the element of rotation, ie cam (basically using kinetic energy conservation, system 2.1).                                                                                                                                              2 22 0 2 0 2 2 00 2 0 2* 2 0 22 2 0 2 0 2 0 2 0 2 00 22 0 * 22 0 22 0 2 02 0 222 22 0 0 0 22 0 2 0 222 0 2 0 222 0 222 0 2222222 2 ' ' ' 2 1 22 2 1 8 22 22 2 1 16 1 4 1 2 1 ' '2 ' 2 ' 2 ' ' 2 cossin2 cos2cos sin2sin 2 1 sm esss ssese rm smssmrrrrmj hm e hh s h se h e rm hmhsmrrrrmj esss eser esss ssr ssrer esss ss ssr esss es erssrer sserssrer ssrrss rereyxrr rmj tbc ccbbc t bc ccbbcm b b ba b bba bba bb bbaaa ccama          ...(2.1) we considered the law of motion of the tappet classic version already used the cosine law (both ascending and descending). the angular velocity is a function of the cam position () but also its rotation speed (2.2). where ωm is the nominal angular velocity of cam and express at the distribution mechanisms based on the motor shaft speed (2.3). 2 * * 2 m m j j   ...(2.2) 60260 2 60 22 nn n motor c cm        ...(2.3) we start the simulation with a classical law of motion, namely the cosine law. to climb cosine law system is expressed by the relationships (2.4).                                                            uu r uu r uu r u h s h as h vs hh s                    sin 2 ''' cos 2 '' sin 2 ' cos 22 3 3 2 2 ...(2.4) where  takes values from 0 to u. jmax occurs for =u/2. with the relation (2.5) is expressed the first derivative of the reduced mechanical moment of inertia. it is necessary to determine the angular acceleration (2.6).                           2/322 0 0 2 0 2 2/322 0 22 00 0 *' ' ''''' ' ''2'' '''2'' esss sessssssese rm esss essssssse rm ssmssmssmj bc bc tcc         ...(2.5) differentiating the formula (2.2), against time, is obtained the angular acceleration expression (2.6). * *'2 2 j j    ...(2.6) relations (2.2) and (2.6) a general nature and are basically two original equations of motion, crucial for mechanical mechanisms. for a rotary cam and translated tappet with roll mechanism (without valve), dynamic movement tappet is expressed by equation (2.7), which is an florian ion t. petrescu al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 123 (2014) 12 original dynamic equation deduced for the distribution mechanism (50) and now by canceling the valve mass, will customize and reaching form below (2.7).             kk xk skk skkxkskkksmkk sx t 02 0 2222 )(2 )(2)2(')(  ...(2.7) where x is the dynamic movement of the pusher, while s is its normal, kinematics movement. k is the spring constant of the system, and k is the spring constant of the tappet spring. it note, with x0 the tappet spring preload, with mt the mass of the tappet, with ω the angular rotation speed of the cam (or camshaft), where s’ is the first derivative in function of  of the tappet movement, s. differentiating twice successively, the expression (2.7) in the angle , we obtain a reduced tappet speed (equation 2.8), and reduced tappet acceleration (2.9).                                       2 02 0 0 22 0 2222 2 '' ' '2'22'''2 )(2)2(')( kk kx skk m sx sn kk kx s skkkxsskkkssmkkm skkxkskkksmkkn t t   …(2.8)                                                                                             3 02 00 0 22 22 0 0 22 0 2222 2 '2'' '''' ''2'''22 ''''''2 ' '2'22'''2 )(2)2(')( kk kx skk sm kk kx ssn kk kx so sx skkxkssskkk sssmkko sn kk kx s skkkxsskkkssmkkm skkxkskkksmkkn t t t    …(2.9) further the acceleration of the tappet can be determined directly real (dynamic) using the relation (2.10).   ''' 2 xxx ...(2.10) 3. new dynamic synthesis give the following parameters: r0=0.013 [m]; rb=0.005 [m]; h=0.008 [m]; e=0.01 [m]; x0=0.03 [m]; u=/2; c=/2; k=5000000 [n/m]; k=20000 [n/m]; mt=0.1 [kg]; mc=0.2 [kg]; nmotor=5500 [rot/min]. to sum up dynamically based on a computer program, you can vary the input data until the corresponding acceleration is obtained (see figure 11). it then summarizes the corresponding cam profile (figure 12) using the relations (2.11). fig. 11. dynamic diagram to the rotary cam with translated follower with roll.                                                            coscossinsin sincoscossin cossin sincos cos sin 0 0 0 bbc bbc ttc ttc bt bt rssrey rssrex yxy yxx rssy rex ...(2.11) florian ion t. petrescu al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 123 (2014) 13 fig. 12. the cam profile to the rotary cam with translated follower with roll; rb=0.003 [m]; e=0.003 [m]; h=0.006 [m]; r0=0.013 [m]; 0=/2 [rad];. 3.1. the new geometry of the rotary cam and the translated follower with roll now, we shall see the geometry of a rotary cam with translated follower with roll (figure 13). the cam rotation sense is positive (trigonometric). we can make the geometrical synthesis of the cam profile with the help of the cinematics of the mechanism. one uses as well the reduced speed, s’. oa=r=ra; r 2 =ra 2 it establishes a system fixed cartesian, xoy = xfoyf, and a mobil cartesian system, xoy = xmoym fixed with the cam. from the lower position 0, the tappet, pushed by cam, uplifts to a general position, when the cam rotates with the  angle. the contact point a, go from ai 0 to a 0 (on the cam), and to a (on the tappet). the position angle of the point a from the tappet is f, and from the cam is m. we can determine the coordinates of the point a from the tappet (2.12), and from the cam (2.13).       ffab f at ffab f at rrrssyy rrrexx   sinsincos coscossin 0 ...(2.12)                                sinsincoscossincos cossincossinsinsin sincoscossinsincos sinsincoscoscoscos 0 0 bbtt fffma m ac bbtt fffma m ac rerssxy rrrryy rssreyx rrrrxx …(2.13) f m   a 0 ia 0a o fx fy mx 0b b  e s 0s  r 0r 0r br br  br 0 fig. 13. the geometry of the rotary cam with translated follower with roll. one uses and the next relationships (2.14), where the pressure angle  was obtained with the classic antonescu p. method [2].                            22 0 22 0 0 22 00 ' ' sin ' cos esss es esss ss errs b   ...(2.14) 3.2. determining the forces, the velocities and the efficiency the driving force fm, perpendicular on r in a, is divided in two components: fn, the normal force, and fa, a force of slipping. fn is divided, as well, in two components: ft is the transmitted (the utile) force, and fr is a radial force which bend the tappet (see 2.15, and the figure 14). florian ion t. petrescu al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 123 (2014) 14                                                                           cossin2 cossin ;; 2 cos ; 22 ; coscoscoscos coscoscoscos coscoscos coscoscos cos cos 0 2 0 22 2 0 222 2 0 2 222 222 sserssrerr rssreyxr sser rr rrr a aa vf vf vf vf p p vvv fff vv ff bba bbafaf b b bb mm mm mm tt c u i mnt mnt mn mn … (2.15) f m   a 0 ia 0a o fx fy mx 0b b  e s 0s  r 0r 0r br br  br 0 tf rf nf nf mf af   fig. 14. forces and velocities of the rotary cam with translated follower with roll. 3.3. new geometro-kinematics synthesis for a good work one proposes to make a new geometric and kinematics synthesis of the cam profile, using some new relationships for the pressure angle delta (2.16). the new synthesis relations already presented (2.12 and 2.13) will use delta pressure angle, deduced now with new relationship (2.16).       ffab f at ffab f at rrrssyy rrrexx   sinsincos coscossin 0 ...(2.12)                             sinsincoscossincos cossincossinsinsin sincoscossinsincos sinsincoscoscoscos 0 0 bbtt fffma m ac bbtt fffma m ac rerssxy rrrryy rssreyx rrrrxx …(2.13) one uses and the next relationships (where the pressure angle  was obtained with the new method):                                                                                              ][2 '2'4'4 arccossinsin ][2 '2'4'4 arccos cosarccos ][2 '2'4'4 cos 22 0 22 00 2 0 22 0 22 00 2 0 22 0 22 00 2 0 22 00 ess sesesssssss ess sesesssssss ess sesesssssss errs b     ...(2.16) the new profile can be seen in the figure 15. fig. 15. the new cam profile to the rotary cam with translated follower with roll; rb=0.003 [m]; e=0.003 [m]; h=0.006 [m]; r0=0.013 [m]; 0=/2 [rad]; florian ion t. petrescu al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 123 (2014) 15 3.4. demonstration (explication) the original relationships (2.16) have been deduced by the expressions (2.17). classical method uses to the geometric synthesis and the reduced tappet velocity, and in this mode the geometric classic method become a geometric and kinematic synthesis method. the new geometric synthesis method uses just the geometric parameters (without velocities), but one utilizes and a condition to realize at the tapped the velocities predicted by the tapped movement laws imposed by the cam profile.                                                                                                                                                ][2 '2'4'4 cos ][2 '4'2'2 cos 0'cos'2cos cos'2cos'coscos cos'cos1cos coscossin' cossin cos ' cossincossincossinsin sin cos ' sin cos ' sinsin sin cos ' sin 2 cos 2 coscos 22 ;; 2 coscos'coscos 22 0 22 00 2 0 22 0 22 0 2 22 0 2 02 222 0 422 0 242242 0 22 0 22 0 2 0 0 0 ess sesesssssss ess essssessesss ssessess seesssss esss esss r ess r s r e r ss bbb b r s b r r r s b r r a a r s aaa aa rsrs bb bb ba b a a b a aa                         ...(2.17) then, it makes the dynamic analyze for the imposed cam profile, and one modify the cam profile geometric parameters to determine a good dynamic response (functionality). in this mode it realizes the dynamic synthesis of the cam, and we obtain a normal functionality. the synthesis was made using the natural geometro-kinematics parameters (of cam mechanism). it follows the proper functioning dynamics. we will optimize and the couple cam-pusher efficiency. forces, velocities and accelerations are also limited. 3.5. increasing the mechanical efficiency at the rotary cam and translated follower with roll the used law is the classical law (2.4), cosine law. the synthesis of the cam profile can be made with the relationships (3.1) when the cam rotates clockwise and with the expressions from the system (3.2) when the cam rotates counterclockwise (trigonometric).                   sinsincoscos sincoscossin 0 0 bbc bbc rerssy rssrex …(3.1)                 sinsincoscos sincoscossin 0 0 bbc bbc rerssy rssrex ...(3.2) the r0 (the radius of the base circle of the cam) is 0.013 [m]. the h (the maximum displacement of the tappet) is 0.020 [m]. the angle of lift, u is /3 [rad]. the radius of the tappet roll is rb=0.002 [m]. the misalignment is e=0 [m]. the cosine profile can be seen in the fig. 16. fig. 16. the cosine profile at the cam with translated follower with roll; r0=13[mm], h=20[mm], u=/3[rad], rb=2[mm], e=0[mm]. the obtained mechanical yield (obtained by integrating the instantaneous efficiency throughout the climb and descent) is 0.39 or =39%. the dynamic diagram can be seen in the fig. 17 (the dynamic setting are partial normal). valve spring preload 9 cm no longer poses today. instead, achieve a long arc very hard (k=500000[n/m]), require special technological knowledge. florian ion t. petrescu al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 123 (2014) 16 fig. 17. the dynamic diagram at the cosine profile at the cam with translated follower with roll; r0=13[mm]; h=20[mm]; u=/3[rad]; rb=2[mm]; e=0[mm]; n=5500[rpm]; x0=9[cm]; k=500[kn/m] it tries increase the yield [8-9, 15-16]; angle of climb is halved u=/6[rad] (see the profile in the fig. 18). the r0 (the radius of the base circle of the cam) is 0.015 [m]. the h (the maximum displacement of the tappet) is 0.010 [m]. the angle of lift, u is /6 [rad]. the radius of the tappet roll is rb=0.002 [m]. the misalignment is e=0 [m]. the cosine profile can be seen in the fig. 18. fig. 18. the cosine profile at the cam with translated follower with roll; r0=15[mm], h=10[mm], u=/6[rad], rb=2[mm], e=0[mm]. the obtained mechanical yield (obtained by integrating the instantaneous efficiency throughout the climb and descent) is 0.428 or =43%. the dynamic diagram can be seen in the fig. 19 (the dynamic setting are not normal). valve spring preload 20 cm no longer poses today. instead, achieve a long arc very-very hard (k=1500000[n/m]), require special technological knowledge. fig. 19. the dynamic diagram at the cosine profile at the cam with translated follower with roll; r0=15[mm]; h=10[mm]; u=/6[rad]; rb=2[mm]; e=0[mm]; n=5500[rpm]; x0=20[cm]; k=1500[kn/m] camshaft runs at a shaft speed halved (nc=n/2). if we more reduce camshaft speed by three times (nc=n/6), we can reduce and the preload of the valve spring (x0=5[cm]); see the dynamic diagram in the fig. 20. however, in this case, the cam profile should be tripled (see the fig. 21). -1400 -1200 -1000 -800 -600 -400 -200 0 200 400 600 0 50 100 150 200 250 300 350 400 xpp [m/s2] xpp [m/s2] -1400 -1200 -1000 -800 -600 -400 -200 0 200 400 600 0 50 100 150 200 250 300 xpp [m/s2] -1400 -1200 -1000 -800 -600 -400 -200 0 200 400 600 0 50 100 150 200 xpp [m/s2] fig. 20. the dynamic diagram at the cosine tripled profile at the cam with translated follower with roll; r0=15[mm]; h=10[mm]; u=/6[rad]; rb=2[mm]; e=0[mm]; n=5500[rpm]; x0=5[cm]; k=1500[kn/m]. florian ion t. petrescu al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 123 (2014) 17 fig. 21. the cosine tripled profile at the cam with translated follower with roll; r0=15[mm], h=10[mm], u=/6[rad], rb=2[mm], e=0[mm]. it tries increase the yield again; angle of climb is reduced to the value u=/8[rad]. the r0 (the radius of the base circle of the cam) is 0.013 [m]. the h (the maximum displacement of the tappet) is 0.009 [m]. the angle of lift, u is /8 [rad]. the radius of the tappet roll is rb=0.002 [m]. the misalignment is e=0 [m]. the cosine profile can be seen in the fig. 22. fig. 22. the cosine profile at the cam with translated follower with roll; r0=13[mm], h=9[mm], u=/8[rad], rb=2[mm], e=0[mm]. the obtained mechanical yield (obtained by integrating the instantaneous efficiency throughout the climb and descent) is 0.538 or =54%. the dynamic diagram can be seen in the fig. 23 (the dynamic setting are not normal). valve spring preload 30 cm no longer poses today. instead, achieve a long arc very-very hard (k=1600000[n/m]), require special technological knowledge. fig. 23. the dynamic diagram at the cosine profile at the cam with translated follower with roll; r0=13[mm]; h=9[mm]; u=/8[rad]; rb=2[mm]; e=0[mm]; n=5000[rpm]; x0=30[cm]; k=1600[kn/m] florian ion t. petrescu al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 123 (2014) 18 camshaft runs at a shaft speed halved (nc=n/2). if we more reduce camshaft speed by four times (nc=n/8), we can reduce and the preload of the valve spring, x0=9[cm] and the elastic constant of the valve spring, k=15000[n/m]; see the dynamic diagram in the fig. 24. however, in this case, the cam profile should be fourfold (see the fig. 25). -4000 -3000 -2000 -1000 0 1000 2000 3000 4000 0 50 100 150 200 250 300 350 400 xpp [m/s2] xpp [m/s2] -4000 -3000 -2000 -1000 0 1000 2000 3000 4000 0 50 100 150 200 250 300 350 400 xpp [m/s2] -4000 -3000 -2000 -1000 0 1000 2000 3000 4000 0 50 100 150 200 xpp [m/s2] -4000 -3000 -2000 -1000 0 1000 2000 3000 4000 0 50 100 150 200 250 300 xpp [m/s2] fig. 24. the dynamic diagram at the cosine fourfold profile at the cam with translated follower with roll; r0=13[mm]; h=9[mm]; u=/8[rad]; rb=2[mm]; e=0[mm]; n=5000[rpm]; x0=9[cm]; k=15[kn/m] fig. 25. the cosine fourfold profile at the cam with translated follower with roll; r0=13[mm], h=9[mm], u=/8[rad], rb=2[mm], e=0[mm]. with the same angle of climb u=/8[rad], can increase performance even further, if the size tappet race take a greater value (h=12[mm]). the r0 (the radius of the base circle of the cam) is 0.013 [m]. the h (the maximum displacement of the tappet) is 0.012 [m]. the angle of lift, u is /8 [rad]. the radius of the tappet roll is rb=0.002 [m]. the misalignment is e=0 [m]. the cosine profile can be seen in the fig. 26. fig. 26. the cosine profile at the cam with translated follower with roll; r0=13[mm], h=12[mm], u=/8[rad], rb=2[mm], e=0[mm]. for correct operation it is necessary to decrease the speed of the camshaft four times, and all four times multiplication of the cam profile. camshaft runs at a shaft speed halved (nc=n/2). if we more reduce camshaft speed by four times (nc=n/8), we can reduce and the preload of the valve spring, x0=9[cm]. the elastic constant of the valve spring is k=1500000[n/m]. see the dynamic diagram in the fig. 27. however, in this case, the cam profile should be fourfold. the obtained mechanical yield is 0.60 or =60%. florian ion t. petrescu al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 123 (2014) 19 -2000 -1500 -1000 -500 0 500 0 50 100 150 200 250 300 350 400 xpp [m/s2] xpp [m/s2] -2000 -1500 -1000 -500 0 500 0 50 100 150 200 250 300 350 400 xpp [m/s2] -2000 -1500 -1000 -500 0 500 0 50 100 150 200 250 300 xpp [m/s2] -2000 -1500 -1000 -500 0 500 0 50 100 150 200 xpp [m/s2] fig. 27. the dynamic diagram at the cosine fourfold profile at the cam with translated follower with roll; r0=13[mm]; h=12[mm]; u=/8[rad]; rb=2[mm]; e=0[mm]; n=5000[rpm]; x0=9[cm]; k=1500[kn/m] for now is necessary to stop here. if we increase h, or decrease the angle u, then is tapering cam profile very much. we must stop now at a yield value, =60%. nomenclature m the mass of the mechanism, reduced at the valve k the elastically constant of the system k the elastically constant of the valve spring dt dm c  2 1 the coefficient of the system’s amortization f0 the elastically force which compressing the valve spring rf the resistant force mf the motor force x the effective displacement of the valve x0 the valve (tappet) spring preload x’ the reduced valve (tappet) speed x’’ the reduced valve (tappet) acceleration ys the theoretical displacement of the tappet reduced at the valve, imposed by the cam’s profile y’s’ the velocity of the theoretical displacement of the tappet reduced at the valve, imposed by the cam’s profile mt=m2 the mass of the tappet (of the valve lifter) m3 the mass of the valve push rod m5 the valve mass j1=jc the inertia mechanical moment of the cam j4 the inertia mechanical moment of the valve rocker 2y the tappet velocity, or the second movement-low, imposed by the cam’s profile x the real (dynamic) valve velocity x the real (dynamic) valve acceleration i=i25 the ratio of transmission tappetvalve, given from the valve rocker y the tappet velocity reduced at the valve d the dynamic transmission function (the dynamic transmission coefficient) ωm the nominal (average) angular velocity of cam ω=1= the angular (real) rotation speed of the cam (or camshaft) 4 the angular rotation speed of the valve rocker  the pressure angle  the additional pressure angle rb roll radius r0 basic radius e horizontally misalignment s0 vertical misalignment ba rr , position vectors j* the reduced mechanical moment of inertia j*’ the first derivative of the reduced mechanical moment of inertia j*m the average reduced moment of inertia florian ion t. petrescu al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 123 (2014) 20 4. discussion in this paper one presents an original method to determine the dynamic parameters at the camshaft (the distribution mechanisms). it makes the synthesis, of the rotary cam and tappet with translational motion with roll, with a great precision. the authors introduce a new pressure angle, alpha, and a new method to determine the two pressure angles, alpha and delta. the presented method is the most elegant and direct method to determine the kinematics and dynamic parameters. the dynamic synthesis can generate a cam profile which will work without vibrations. processes robotization increasingly determine and influence the emergence of new industries, applications in specific environmental conditions, approach new types of technological operations, handling of objects in outer space, leading teleoperator in disciplines such as medicine, robots that covers a whole larger service benefits our society, modern and computerized. in this context, this paper seeks to contribute to the scientific and technical applications in dynamic analysis and synthesis of cam mechanisms. in 1971 k. hain proposes an optimization method to cam mechanism to achieve the optimum output transmission angle (maximum) and minimum acceleration [11]. in 1979 f. giordana investigates the influence of measurement errors in kinematic analysis of cam [10]. in 1985 p. antonescu presents an analytical method for the synthesis mechanism flat tappet cam and tappet rocker mechanism [2]. in 1987 f.i. petrescu presents a new dynamic model with general applications [3]. in 1988 j. angelas and c. lopez-cajun presents optimal synthesis mechanism oscillating flat tappet cam and [1]. in 1991 b.s. bagepalli presents a generalized model of dynamic cam-follower pairs [4]. in 1999 r.l. norton studying the effect of valve-cam ramps on the valve-train dynamics [12]. z. chang presents in 2001 [5] and 2011 [6] a study on dynamics of roller gear cam system, considering clearances. in 2002 d. taraza synthesized analyzes the influence of the cam profile, the variation of the angular velocity distribution tree, and the parameters of power load consumption and emissions of internal combustion engine [16]. in 2005 [13] and 2008 [14], f.i. petrescu and r.v. petrescu present a synthesis method of rotary cam profile, and translational or rotary tappet, flat or with roll, to obtain high yields output. in 2009 k. dan makes some research on dynamic behavior simulation technology for camdrive mechanism in single-cylinder engines [7]. in 2009 m. satyanarayana makes a dynamic experiment in cam-follower mechanism [15]. in 2011 z. ge makes the design and dynamic analysis of the cam mechanisms [8-9]. 5. conclusions the distribution mechanisms work with small efficiency for about 150 years; this fact affects the total yield of the internal heat engines. much of the mechanical energy of an engine is lost through the mechanism of distribution. multi-years the yield of the distribution mechanisms was only 48%. in the past 20 years it has managed a lift up to the value of 14-18%; car pollution has decreased and people have better breathing again. meanwhile the number of vehicles has tripled and the pollution increased again. now, it’s the time when we must try again to grow the yield of the distribution mechanisms. the paper presents an original method to increase the efficiency of a mechanism with cam and follower, used at the distribution mechanisms. this paper treats only one module: the mechanism with rotary cam and translated follower with roll (the modern module b). at the classical module c we can increase again the yield to about 30%. the growth is difficult. dimensional parameters of the cam must be optimized; optimization and synthesis of the cam profile are made dynamic, and it must set the elastic (dynamic) parameters of the valve (tappet) spring: k and x0. the law used is not as important as the module used, sizes and settings used. we take the classical law cosine; dimensioning the radius cam, lift height, and angle of lift. to grow the cam yield again we must leave the classic module c and take the modern module b. in this way the efficiency can be as high as 60%. yields went increased from 4% to 60%, and we can consider for the moment that we have gain importance, since we work with the cam and tappet mechanisms. if we more increase h, or decrease the angle u, then is tapering cam profile very much. we must stop now at a yield value, =60%. florian ion t. petrescu al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 123 (2014) 21 it can synthesize high-speed cam, or highperformance camshafts. 6. references [1] angelas j., lopez-cajun c., optimal synthesis of cam mechanisms with oscillating flat-face followers. mechanism and machine theory 23,(1988), nr. 1., p. 1-6., 1988. [2] antonescu, p., petrescu, f., antonescu, o., contributions to the synthesis of the rotary disc-cam profile, in viii-th international conference on the theory of machines and mechanisms, liberec, czech republic, p. 5156, 2000. [3] antonescu, p., oprean, m., petrescu, f.i., analiza dinamică a mecanismelor de distribuţie cu came. în al vii-lea simpozion naţional de roboţi industriali, mero'87, bucureşti, 1987, vol. iii, p. 126-133. [4] bagepalli, b.s., a.o., generalized modeling of dynamic cam-follower pairs in mechanisms, journal of mechanical design, june 1991, vol. 113, issue 2, p. 102-109. [5] chang, z., a.o., a study on dynamics of roller gear cam system considering clearances, mechanism and machine theory, january 2001, vol. 36, n. 1, p. 143-152. [6] chang, z., a.o., effects of clearance on dynamics of parallel indexing cam mechanism, icira’11 proceedings of the 4th international conference on intelligent robotics and applications – volume, part i, 2011, p. 270-280. [7] dan, k., a.o., research on dynamic behavior simulation technology for cam-drive mechanism in single-cylinder engines, sae technical paper, 2009, paper number 200932-0089. [8] ge, z., a.o., mechanism design amd dynamic analysis of hybrid cam-linkage mechanical press, key engineering materials journal, vol. 474-476 (2011), p. 803-806. [9] ge, z., a.o., cad/cam/cae for the parallel indexing cam mechanisms, applied mechanics and materials journal, vol. 44-47 (2011), p. 475-479. [10] giordana f., s.a., on the influence of measurement errors in the kinematic analysis of cam. mechanism and machine theory 14 (1979), nr. 5., p. 327-340, 1979. [11] hain k., optimization of a cam mechanism to give goode transmissibility maximal output angle of swing and minimal acceleration. journal of mechanisms 6 (1971), nr. 4., p.419-434. [12] norton, r.l., a.o., effect of valve-cam ramps on valve train dynamics, sae, international congress & exposition, 1999, paper number 1999-01-0801. [13] petrescu, f.i., petrescu, r.v. contributions at the dynamics of cams. in the ninth iftomm international symposium on theory of machines and mechanisms, syrom 2005, bucharest, romania, 2005, vol. i, p. 123-128. [14] petrescu f.i., ş.a., cams dynamic efficiency determination. in new trends in mechanisms, ed. academica greifswald, 2008, i.s.b.n. 978-3-94023710-1, p. 49-56. [15] satyanarayana, m., a.o., dynamic response of cam-follower mechanism, sae technic paper, 2009, paper number 2009-01-1416. [16] taraza, d., "accuracy limits of imep determination from crankshaft speed measurements," sae transactions, journal of engines 111, p. 689-697, 2002. florian ion t. petrescu al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 123 (2014) 22 authors’ information 1 dr. eng. florian ion t. petrescu, senior lecturer at upb (bucharest polytechnic university), tmr (theory of mechanisms and robots) department. 2 dr. eng. relly victoria v. petrescu, senior lecturer at upb (bucharest polytechnic university), ttl (transport, traffic and logistics) department. 1. ph.d. eng. florian ion t. petrescusenior lecturer at upb (bucharest polytechnic university), theory of mechanisms and robots department, date of birth: march.28.1958; higher education: polytechnic university of bucharest, faculty of transport, road vehicles department, graduated in 1982, with overall average 9.63; doctoral thesis: "theoretical and applied contributions about the dynamic of planar mechanisms with superior joints". expert in: industrial design, mechanical design, engines design, mechanical transmissions, dynamics, vibrations, mechanisms, machines, robots. association: member arotmm, iftomm, siar, fisita, srr, agir. member of board of srrb (romanian society of robotics). 2. ph.d. eng. relly victoria v. petrescu senior lecturer at upb (bucharest polytechnic university), transport, traffic and logistics department, citizenship: romanian; date of birth: march.13.1958; higher education: polytechnic university of bucharest, faculty of transport, road vehicles department, graduated in 1982, with overall average 9.50; doctoral thesis: "contributions to analysis and synthesis of mechanisms with bars and sprocket". expert in industrial design, engineering mechanical design, engines design, mechanical transmissions, projective and descriptive geometry, technical drawing, cad, automotive engineering, vehicles, transportations. association: member arotmm, iftomm, siar, fisita, srr, sorging, agir. florian ion t. petrescu (2014) 6582، صفحة 1، العدد10دمجلة الخوارزمي الهندسية المجل التركيب الديناميكي للحدبات florian ion t. petrescu* relly victoria v. petrescu** * اوربا/ رومانيا / جامعة بوخارست / قسم نظريات المكائن واالنسان االلي اوربا/ رومانيا / جامعة بوخارست / قسم النقل والمواصالت ** petrescuflorian@yahoo.com : االتلكتروني البريد* petrescuvictoria@yahoo.com : االلكتروني البريد** الخالصة يستخدم األسلوب التقليدي في وصف . لتركيب الهندسي للحدبات الدوارة وانتقال التابع الملتصق اثناء االندفاع يقدم هذا البحث طريقة جديدة لوصف ا ركيب تستخدم طريقة الت. التركيب الهندسي وتقليل سرعة التابع المندفع، وفي هذا الوضع فان األسلوب الكالسيكي يصبح كطريقة تركيب هندسية وحركية ، ولكن يمكن استخدام ومعاينة سرعة التابع المندفع المتحققة والتي يمكن تنبأها من خالل قوانين الحركة (بدون السرعات)الهندسية الجديدة المحددات الهندسية حيث يمكن من .اميكي الجيد في العمل والتعديل على محدداتها لحساب التصرف الدين عندها يتم التحليل الديناميكي لشكل الحدبة. النتجة من شكل الحدبة .خالل هذا الوضع ادراك التركيب الديناميكي االمثل للحصول على االداء االعتياد mailto:petrescuflorian@yahoo.com*البريد mailto:petrescuflorian@yahoo.com*البريد mailto:petrescuvictoria@yahoo.com**البريد mailto:petrescuvictoria@yahoo.com**البريد \(microsoft word \\332\\341\\355\\307\\301 \\332\\325\\307\\343\) al-khwarizmi engineering journal, vol. 9, no. 4, p.p. spectral study of pt (ii), cr (ii) polymeric complexes of the ligand ncrotonyl department of chemical engineering / university of technology (received 5 abstract the polymeric complexes were obtained from the reaction of polymeric schiff base.n hydroxyphenylazomethine (hl), with divalent metals complexes were determine through spectroscopic methods and compared with that reported from analogous monomeric ligand. this study revealed square planer geometry around the metal center fo geometry for cr complex [cr(l)cl(h2o) keywords: schiff base, polymeric complexes, spectroscopic methods, divalent metals 1. introduction polymermetal complexes are composed of polymeric ligand and metal ions. they show unique characteristics in absorption spectrum, coordination structure, stability, redox reaction, catalytic activities, electro chemical reactions, and other areas, compared with those of corresponding low – molecular-weight metal complexes. complexation of polymeric ligand with metal ions as well as the ligand substitution reaction of polymer –metal complexes is utilized to separate metal ions and/or small molecules coordination polymers are usually known for their thermal stability [2].however, some other equally good application has been reported such as being used as converters of solar energy and removal of sox and nox from the environment [18]. while (x= the number of oxygen atom). recently, an important new focus for environmental inorganic chemistry has been the selective removal of metal ions from aqueous solution, including waste treatment, with polymer supported chelate system [3]. khwarizmi engineering journal, vol. 9, no. 4, p.p. 3945 (2013) (ii), cr (ii) polymeric complexes of the ligand crotonyl -2hydroxy-phenylazomethine alyaa esam mahdi department of chemical engineering / university of technology email:esammustafa 73@yahoo.com (received 5 september 2013; accepted 20 january 2014) the polymeric complexes were obtained from the reaction of polymeric schiff base.n hydroxyphenylazomethine (hl), with divalent metals pt (ii), cr (ii). the modes of bonding and overall geometry of the complexes were determine through spectroscopic methods and compared with that reported from analogous monomeric revealed square planer geometry around the metal center for [pt(l)cl] and distorted octahedral o)2]. polymeric complexes, spectroscopic methods, divalent metals. metal complexes are composed of and metal ions. they show unique characteristics in absorption spectrum, coordination structure, stability, redox reaction, catalytic activities, electro chemical reactions, and other areas, compared with those of corresponding l complexes. complexation of polymeric ligand with metal ions as well as the ligand substitution reaction of metal complexes is utilized to separate metal ions and/or small molecules [1]. coordination polymers are usually known for .however, some other equally good application has been reported such energy and removal of sox and nox while (x= the number recently, an important new focus for environmental inorganic chemistry has been the selective removal of metal ions from aqueous solution, including waste treatment, with polymer 2. experimental all reagents were obtained commercially (aldrich company, uk) and use purification. ethyl methyl ketone peroxide (emkp) or 2, 2ˋ-azobisisobutyronitrile (aibn) were used as initiator to prepare the ligand .ir spectra recorded as kbr or csi discs using shimadzu 8300ftir spectrophotometer in the rang 4000-250cm-1. electronic spectra were measured in the region 200 solutions in dmf at 25o spectrophotometer. conductivity measurements were made in dmf using a jenway 4071 digital conductivity meter. 3. preparation of the complexes a mixture of the ligand hl (1mmol)in methanol (15ml) containing a few drops of hcl was added to a stirred solution of metal salt (1.1mmol) over 15 min using k complex, and crcl3.6h2o for cr complex in hot methanol (15ml) with 32% emkp(1ml) in al-khwarizmi engineering journal (2013) (ii), cr (ii) polymeric complexes of the ligand phenylazomethine department of chemical engineering / university of technology the polymeric complexes were obtained from the reaction of polymeric schiff base.n-crotonyl-2pt (ii), cr (ii). the modes of bonding and overall geometry of the complexes were determine through spectroscopic methods and compared with that reported from analogous monomeric r [pt(l)cl] and distorted octahedral all reagents were obtained commercially (aldrich company, uk) and used without ethyl methyl ketone peroxide azobisisobutyronitrile (aibn) were used as initiator to prepare the ligand .ir spectra recorded as kbr or csi discs using shimadzu 8300ftir spectrophotometer in the electronic spectra were measured in the region 200-900 nm using 10-3m oc using shimadzu 160 spectrophotometer. conductivity measurements were made in dmf using a jenway 4071 digital preparation of the complexes a mixture of the ligand hl (1mmol)in methanol (15ml) containing a few drops of hcl was added to a stirred solution of metal salt (1.1mmol) over 15 min using k2 ptcl4 for pt o for cr complex in hot methanol (15ml) with 32% emkp(1ml) in alyaa esam al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 3945 (2013) 40 methanol (30ml) as the initiator. as shown in scheme (1). the resulting mixture was refluxed under n2 atmosphere for 3h, resulting in the formation of colored solution. the solution was concentrated by slow evaporation of the methanol at room temperature. the solid product formed was collected by filtration and washed with ethanol (10ml) and finally with diethyl ether (15ml). the above procedure was used to give a dark brown solid for pt2+ complex and yellowish green for cr2+ complex. scheme (1) preparation of cr, pt complexes. 4. result and discussion the reaction of salicylaldehyde with acrylamide afforded the new schiff base ncrotonyl-2-hydroxy phenylazomethine hl in good yield. (scheme2) scheme (2) schiff base hl. the ir spectrum for the ligand fig (1-a) shows a distinct band at 1666 cm-1 due toν(c=o).the spectrum also shows characteristic bands related to the, ν (c=n ) ,ν(c=c) and ν(o-h) functional groups (table 1) [4,5].the u.v-vis spectrum of hl fig (1-b)exhibits an intense absorption peak at 260 and 277 nm, which assigned to π → π∗, and an absorption peak at 325 nm assigned to n→ π∗ [table 2]. the polymeric complexes were synthesized by heating 1mmole of schiff base with 1.1 mmole of the metal chloride, in methanol using mekp or aibn as initiator and a few drops of concentrated hcl [17]. the two complexes [cr(l)cl (h2o)2] and [pt(l)cl] were obtained. the important infrared bands for the complexes together with their assignments are listed in [table 1]. the ir spectra of the complexes figures (2, 3) exhibited hl bands with appropriate shifts due to complex formation [table 1]. the two complexes show a strong band at (1628.9-1631.7) cm-1, assigned to a ν (c=n) stretch of reduced bond order [6].this can be attributed to delocalization of metal electron density (t2g) to the π system of the ligand. theν (c=o) stretching band at 1666cm-1 in the free ligand is shifted to lower frequency and observed around (1668.3-1653) cm-1 for the complexes, indicating coordination of the oxygen of theν (c=o) group to the metal [7].in the ir spectrum of the pt(ii)complex, theν (c=o) small shift of 2.3 cm-1on complexation could be attributed to the weak linkage between the oxygen atom and metal centre . at lower frequency the complexes exhibit bands around (590 – 540) and (430-450) cm-1 which are assigned toν (m-o) and ν (m – n), respectively [15]. an additional band observed around 3398.3 cm-1in [cr (l) cl (h2o)2] is assigned to coordinated aqua (h2o) ligands [14]. the molar conductivity measurement for the complexes between 15 and 20 s.cm2mole-1 indicating their non-electrolytic behavior [8] and o oh n alyaa esam al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 3945 (2013) 41 enhance that the chlor atom is inside the coordination ball [13] .the unit of conductivity is siemens=ohm-1 and the unit of molar conductivity is s.cm2mole-1 . the ir spectra of the complexes exhibit farir active bands around (340-335) cm-1 which are assigned to the ν (m-cl) vibration. these vibrations are characteristic of terminally coordinated chloride [10-11]. the spectra of pt (ii) complex fig (4) shows two bands (271-301) nm related to the ligand field [12] and a peak at 407 nm can be attributed to the1a1g 1b1g transition suggesting square planer structure [17]. the electronic spectra of the cr(ii) , complex fig (5) exhibit a high intensity peak around 214 nm related to the charge transfer transition ,and 224 nm assigned to 1a1g→1b1g transition suggesting distorted octahedral structure [12]. table 1, infrared spectral data (wave number�) ��� for ligand and its complexes. table 2, electronic data of ligand and its metal complexes. compound � � − �) ���� � � = �) � � = �) � �� = �) � � − �) � � = � − �) � � − �) � � − ��) ligand hl 2750 1625 1666 700 ��� �)��� 2390 1628.9 1668.3 746.4 430 682.8 590 340 ��� �)�� ���)� � 2335 1631.7 1653 750 450 592 540 355 compound !� � " # �$ !%�&$���� '()* �+� �� ��� assignment ligand hl 260 38461 1500 π → π∗ 277 36101 2039 → -∗ 325 30769 72 . → -∗ ��� �)�� ���)�� 214 46728 414 charge transfere 224 44642 336 ′012 → 312 ��� �)��� 271 36900 1940 ligand field 301 33222 1431 ligand field 407 24570 611 ′012 → 312 alyaa esam fig. 1 fig. 1 fig. 2 al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 42 1-a. infrared spectrum of the ligand (hl). -b. electronic spectrum of the ligand (hl). 2. infrared spectrum of � �� �)��� complex. ng journal, vol. 9, no. 4, p.p. 3945 (2013) alyaa esam al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 3945 (2013) 43 fig. 3. infrared spectrum of ��� �)�� ���)�� complex. fig. 4. electronic spectrum of� �� �)��� complex. fig. 5. electronic spectrum of ��� �)�� ���)��complex. alyaa esam al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 3945 (2013) 44 5. conclusion in the present work the synthesis and spectral study of coordination complexes from polymer of the schiff base hl have been explored. in these complexes, the metal center is still able to adjust its preferred geometry which involves (c=o) coordination via its oxygen atom. depending on spectral study of uv and ir spectrum and conductivity measurement, the proposed structure of the complexes were expected as follow: square planer for [pt(l)cl] and distorted octahedral for [cr(l)cl(h2o)2]. 6. references [1] sushmita m. roy,h.d.juneja,and k.n munshi syn.react.inorg.met.org.chem,31(9),1611-1621 (2001). [2] adel zel-sonbati,ashraf a el-bindary and naglaa a-el-deeb designed monomers and polymers vol 4, no. 4, pp 357-367 (2001) [3] mohammed jaber al-jeboori,ahmed t. numan , journal ibn al-haitham pure & applied sciences 21. 89 (2008). [4] nyquist ra spectrochim acta 23 a: 1635 0584-8539 (73) 80113-8. (1973) [5] silverstein rm,bassler gg morril tc spectrometric identification of organic compound 4th edn. wiely new york. (1981) [6] pinchas s, benishai d amer chem. soc 79:4099 doi: 10.102/ja 01572a 35. (1957) [7] i.b.liss.feand e.o schlemper inorg chem., 14, 303, (1975). [8] el-sonbati az ,elbindary aa new polym mater 5:51(1996) [9] nakomoto n, infrared sepectra of inorganic and coordination compounds,vol 4. wiley,new york. (1996) [10] ahsen v, gök f ,bekarogluö, j chem. soc, dalton trans 1827 .doi 10. 1039/dt987000 1827. (1987) [11] lever abp inorganic electronic spectroscopy vol 2. elesvier publishing new york. (1984) [12] el-sonbati az, el-bindary aa, diab ma, spectro himic aacta part a:443,doi 10.1016/s1386 -1425 (02)00222-6. (2003) [13] belghoul b welterlich ,w,maiera,t,outianoush a, rabindranath a, rabindrinath ar,tieke b, langmuir 23:5062. (2007) [14] seddique m. ahmed, mohamed m. shahata and mostafa m. kamal journal of inorganic and organometalic polymers, vol. 13, no 3, sep. (2003). [15] a.a el-bindari, a. s. al-shihri and a.z. el-sonbati designed monomers and polymers. vol 6, no. 3, pp 283-298 (2003). [16] s.m.ropy,h.d.juneja,k.n.munshi.synth.r eact.inorg.met-org.chem,31(9),16111621(2001). [17] a.a.el-bindary,a.s. alshihri,a.z.elsonbati,designed monomers and polymers,6,3,283-298(2003). [18] toshima,n.removal of harmful gases by polymer complexes ,kogya zairyo,39,45(1991). )2013( 3945، صفحة 4، العدد9مجلة الخوارزمي الھندسية المجلد علياء عصام مھدي 45 cr (ii) لليكند , pt (ii), الدراسة الطيفية للمعقدات البوليميرية لكل من ncrotonyl -2hydroxy-phenylazomethine مھدي علياء عصام الجامعة التكنولوجية/ قسم الھندسة الكيمياوية yahoo.comesammustafa@73 :البريد ا�لكتروني الخ)صة ncrotonyl -2hydroxy-phenylazomethin بلمرلليكند المت )قاعدة شيف(يمكن الحصول على المعقدات البوليميرية عن طريق تفاعل [hl]. نوع التأصر والشكل الھندسي الكلي للمعقدات يمكن الحصول عليه عن طريق الدراسات الطيفية ومقارنتھا بالنسبة للمعقد . مع عناصر ثنائية التكافؤ واما بالنسبة لمعقد الكروم . ھو مربع مستوي [pt(l)cl] ھذه الدراسات أظھرت ان الشكل الفراغي لمركز العنصر بالنسبة لمعقد االبbتين) ا�صلي(ا�حادي [cr(l)cl(h2o)2] فقد كان ثماني السطوح مشوه. characterization of delamination effect on free vibration of composite laminates plate using high order shear deformation theory al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 8, no. 1, pp 1 10 (2012) wlan integrated with gprs network securely mohammed a. abdalla* khalifa a. salim** zinah jaafar mohammed *** *department of information and communication engineering/ college of information engineering/ university of al-nahrain **department of information and communication engineering /al-khawarizmi college of engineering / university of baghdad ***department o computer engineering and information technology/university of technology * email: mohammedalmushdany@yahoo.com ** email: khalifaabboud@yahoo.com *** email: zinahameen83@yahoo.com (received 24 march 2011; accepted 18 october 2011) abstract in this paper a wlan network that accesses the internet through a gprs network was implemented and tested. the proposed network is managed by the linux based server. because of the limited facilities of gprs such as dynamic ip addressing besides to its limited bandwidth a number of techniques are implemented to overcome these limitations. dynamic host configuration protocol (dhcp) server was added to provide a single central control for all tcp/ip resources. squid proxy was added to provide caching of the redundant accessed web content to reduce the internet bandwidth usage and speeding up the client’s download time. network address translation (nat) service was configured to share one ip address among several different systems. in order to accomplish a secure channel to exchange data between two network devices, the secure shell (ssh) protocol was added. the first test shows that the data transfer rate at different time intervals of the day found to be an average of 10.95 kbps for uploading and 13.7 kbps for downloading and the second test shows that the network performance improved when squid proxy cache was used. the data rate found to be 143.3 kbps average for uploading rate and 376.6 kbps average for downloading rate. keywords: gprs, server, openvpn, security. 1. introduction wireless local area networks wlans offer high data rate internet protocol network connectivity using the industrial, scientific and medical (ism) band which is license free radio frequencies, but problems of limited coverage area still exist. wlan networks are mainly an indoor environment for low mobility and high speed applications. the bit rate of ieee 802.11b standard can achieve 11 mbps, while the 802.11g standard can achieve data rate up to 54 mbps [1]. cellular operators are already capable of providing wide coverage area with cellular technologies, with the same wide spread coverage as voice services. besides that, cellular operators have a large customer base which put them in a good position to complement the service offering by wlan. general packet radio service (gprs) is a cellular operator service that supports increased demand for internet services over a wide area besides the mobility needed. gprs is a wide area data solution, but it is not able to support the high data rate required for various applications due to its limited bandwidth. in this work, an integrated wlan combined with gprs network system was implemented and tested to access the internet based on gprs as a service provider. the rest of the paper is organized as follows. section 2 describes the gprs network architecture. in section 3 both mailto:mohammedalmushdany@yahoo.com mailto:khalifaabboud@yahoo.com mailto:zinahameen83@yahoo.com mohammed a. abdalla al-khwarizmi engineering journal, vol. 8, no. 1, pp 1-10 (2012) 2 server implementation and client configuration of the proposed system architecture discussed. section 4 deals with network assessment and finally section 5 lists some concluding remakes. 2. gprs network architecture gprs is a packet-based data bearer service for wireless communication data transfer that is delivered as a network overlay for gsm, cdma and tdma networks. theoretical maximum speed of gprs is up to 171.2 kbps [2]. packet switching means that data is split into packets which are transmitted separately and then reassembled at the receiving end. however, packet switching means there is no dedicated circuit assigned to the gprs mobile phone [3]. a physical channel is established dynamically, only when data is being transferred. once the data has been sent, the resource (a timeslot on the air interface) can be re-allocated to other users for more efficient use of the network. gprs attempts to reuse the existing gsm network elements as much as possible, but in order to effectively build a packet-based mobile cellular network, some new network elements, interfaces, and protocols that handle packet traffic are required. the existing gsm compatible devices do not handle enhanced interfaces, and do not have the ability to packetize traffic directly. either voice or data traffic is originated at the subscriber terminal, which would be transported over the air interface to the base transceiver station (bts), and from the bts to the base switching center (bsc), in the same way as a standard gsm call. however, at the output of the bsc, the traffic is separated to voice which is sent to the mobile switching center (msc) per standard gsm, and data is sent to a new device called the serving gprs support node (sgsn), via the packet control unit (pcu) over a frame relay interface. the sgsn can be viewed as a packet switched msc that delivers packets to mobile stations within its service area. sgsns send queries to the home location register (hlr) to obtain profile data of gprs subscribers. sgsns detect new gprs mobile stations in a given service area, process registration of new mobile subscribers, and keep a record of their location inside a given area [4]. the elements of a gsm/gprs network are shown in figure (1), where the special gprs communication interfaces are indicated. fig. 1.gprs network architecture [5]. 3. proposed system architecture[6] figure (2) shows the network components which consists of a switch used to connect the private network under test with its private range of ip addresses defined by the server and one access point attached to the switch in order to enable client’s hosts attending the network through wi-fi. to set a gprs connection for the network a mobile station is used and configured by the server, hence establishing internet connection via gprs by using the mobile device as modem. mohammed a. abdalla al-khwarizmi engineering journal, vol. 8, no. 1, pp 1-10 (2012) 3 fig. 2.actual implemented and tested network. the system implementation is divided into two steps: 3.1. server implementation gprs connection is established by using mobile device connected to the server via a usb cable or bluetooth as shown in figure (3). fig. 3.establishing internet connection. mohammed a. abdalla al-khwarizmi engineering journal, vol. 8, no. 1, pp 1-10 (2012) 4 the network is managed by the ubuntu linux server. the server is implemented by configuring the dhcp server. it is used to configure all client machines in exactly the same way by configuring them to use the dhcp server. it is also much more reliable than manual tcp/ip management, because the dhcp server is designed to manage its ip pool and the lease periods so that never get two hosts using the same ip address at the same time. dhcp server lease the address to the client for a specified time, a test to the server was done as shown in figure (4). fig. 4.dhcp server leases file. one of the client ip lease that was offered by dhcp server to a client with the host name zeyna-pc. this test confirmed that dhcp service was configured correctly. squid proxy is used for authorization and controlling the web pages filtering. it provides a control point for restricting which of external web sites can be reached. authorization is needed to prevent unauthorized users to access the internet especially through the access point. besides that squid proxy is mainly used to provide web page caching. it caches the commonly accessed web and ftp content locally, thereby reducing the internet bandwidth usage and speeding up client’s download time. squid was checked by viewing the access.log file which provides a valuable source of information about squid workloads and performance. the logs record contains not only access information, but also system configuration errors and resource consumption (such as memory, disk space). as shown in figure (5). fig. 5.access.log file. in order to effectively configure the linux server to operate as router, packet forwarding is enabled, in order to forward the incoming packets on one interface to another based on the packets destination address. each interface must be configured with a unique ip address. if two networks use separate media (ethernet, ppp, other), packets are automatically transformed to match the other medium’s specification. ip tables rules are added to force all the tcp traffic inside the private network with the destination port 80 to be redirected to port 3128, squid’s specified port of the server besides enabling nat/ip masquerading in order to activate internet sharing among the private network computers. to test if nat works properly would be on the clients' side, as the clients can access the internet provided by the server. this means that the added rules worked correctly. open ssh is an open source implementation of the ssh protocol suite that provides encrypted communication sessions over a computer network, enabling remotely controlling a mohammed a. abdalla al-khwarizmi engineering journal, vol. 8, no. 1, pp 1-10 (2012) 5 computer or transferring files between computers securely. traditional tools used to accomplish these functions are insecure and transmit the user’s password in clear text when used. for security consideration, open ssh would listen for the incoming tcp connection on port 8381 instead of its default tcp port 22. open ssh server is configured to enable public key authentication so that the generated keys could be either des or rsa. in order to access the open ssh server remotely besides its local access, both the open ssh server and clients should get ip address from the public range of ip addressing, therefore and for testing purposes hamachi software is suggested. hamachi is a zero configuration vpn application capable of establishing direct links between computers that are behind nat firewalls, in other words, it establishes a connection over the internet that emulates the connection that would exist if the computers were connected over a local area network [7]. hamachi is a centrally managed vpn system, consisting of the server cluster managed by the vendor of the system and the client software, which is installed on end user computers. client software adds a virtual network interface to a computer each client establishes and maintains a control connection to the server [7]. in order to test hamachi, and check if it was installed, configured and would work properly at the server host, ifconfig command was used which displays information on all network interfaces configured in the linux kernel information such as an interface, netmask and the ip address. fig. 6. hamachi virtual network interface. as shown in figure (6), ham0 was created which assigned a class a public ip address that is 5.18.188.135 with network mask 255.0.0.0. open ssh test was done by executing the command netstat, which returns the network information. this command was issued to check if the server is listening for incoming connections as shown in figure (7) the ssh server port was listening and working on 8381 port with process id 5493. fig. 7.checking ssh server. 3.2. client configuration clients’ computers could be either linux based or windows based operating system. clients are configured according to the server settings in order to benefit from its services. each client is assigned a unique ip address provided by the dhcp server besides other parameters. each client was assigned a unique ip address provided by the dhcp server. as shown in figure (8) and according to the dhcp server configuration the client got the following parameters, the connection dns suffix is lab4.local, the ip address that was provided by the dhcp server is 10.66.77.4, the lease time that allocated to this client ip address, the dhcp server ip address and the dns server which are the dns server used by the mobile network as the internet connection was established. fig. 8.dhcp service test. mohammed a. abdalla al-khwarizmi engineering journal, vol. 8, no. 1, pp 1-10 (2012) 6 the clients’ browsers are modified according to the squid proxy setting. squid proxy port besides its ip address are set by the clients, if the clients did not set these parameters, no internet access would be available. clients should prove their authorization by entering a valid username/password as shown in figure (9). username is case insensitive spelling. fig. 9.squid authentication announcement. after authentication process, clients could access the internet within the squid’s rules. according to which time specification is allowed for internet access, otherwise internet access would be rejected by the proxy as shown in figure (10). besides time specification, access to internet would be limited to particular web pages that may adversely affect the bandwidth and would be block downloading .wav or .avi file or www.hacker.com web page. fig. 10. client’s request out of allowable time was rejected. private shell, puttygen and putty software are installed at clients’ windows based computers in order to access the ssh server within the ssh tunnel. only specified clients are allowed to access the ssh server those clients have to be configured with ssh server ip address and port. features provided by the ssh server are: aforwarding gui programs: ssh can forward graphical applications over a network, extra software is required to forward programs to windows based operating system such as xming software. xming is windows based x11 server/client software is downloaded and run at clients’ host. as shown in figure (11) forwarding firefox application. fig. 11.forwarding firefox application. bdynamic port forwarding: which would turn the ssh client into a socks proxy server. socks is a little known but widely implemented protocol by which any internet connection request is done through a socks proxy server, which encrypts the requested data. in order to ensure that the traffic within the ssh tunnel is encrypted, the wire shark software is used to sniff the packets. as shown in figure (12), a sample of captured packets through the ssh tunnel. mohammed a. abdalla al-khwarizmi engineering journal, vol. 8, no. 1, pp 1-10 (2012) 7 fig. 12.plain and encrypted packets within the ssh tunnel. 4. network assessment 4.1. gprs data transfer rate the data transfer rates are tested by uploading data to another network and downloading data from the same network. the gprs getaway limits the uploading rate to approximately 40 kbit/s and the downloading rate to approximately 60 kbit/s. the tests are done at the server computer which means that the tests are directly through gprs connection. the data is transferred to www.testmy.net. the uploaded data size is 1013 kb and the downloaded data size is 1024 kb. the data transfer rates are calculated using the equation: ((data size in bytes) * 8 / transfer time in seconds) / 1000 to get the transfer rate in kbit/s four uploading and downloading tests are performed at different times of the day, the average uploading data transfer rate was 10.95 kbit/s and the average downloading rate was 13.7 kbit/s. figure (13) depicted gprs transfer rates for both upload and download. fig. 13.gprs upload and download data transfer rates. the results of uploading and downloading tests show that the gprs bandwidth variation due to the signal fluctuations and the network traffic generated by other users especially at the network peak time within the period from 11:00 am – 4:00 pm. the average uploading and downloading data transfer rates are lower than the theoretical rates. 4.2. network performance test performance test is done at the network in order to monitor how the gprs connection at the server can handle the traffic generated by users and how web browsing is affected. the test is performed by loading web sites at the server and then requesting the sites at the client's host in order to test the operation of squid proxy cache and its performance enhancement. fig.(14) shows the loading of www.ivsl.com site. the site is loaded within 25 seconds with maximum downloading rate 6 kbit/s and maximum uploading rate 5 kbit/s. this site includes an image. http://www.testmy.net/ http://www.ivsl.com/ mohammed a. abdalla al-khwarizmi engineering journal, vol. 8, no. 1, pp 1-10 (2012) 8 fig. 14.loading the site at the server’s host. as the client requested that site, it was loaded within 4 seconds with maximum downloading rate 850 kbit/s and maximum uploading rate of 150 kbit/s. as shown in figure (15). fig. 15.loading the site at the client’s host. the network performance test reveals the importance of squid proxy existence. as the clients’ requests could be loaded from the squid’s cache if they were saved, this defiantly enhances the network performance. 5. conclusions throughout the work a wlan based on gprs network to get access to the internet was designed and implemented, the following remarks are concluded: aaccessing the internet via a gprs connection by the mobile station has many benefits such as smaller in size, easy to install, costless and mainly its wide coverage area especially for places that have no internet provider available. bdue to the lack of available public ip addresses that was required for the server and a specific clients in order to establish the ssh tunneling, hamachi software was suggested to enable access to the server from remote clients. cin order to overcome the limitation of gprs bandwidth provided by the mobile network operators, squid proxy server was implemented to enhance the network performance. besides its caching squid proxy server restrict the users’ activity while accessing the internet by blocking some of the download features and specific sites. dsecurity considerations were paramount in the implemented network, that rely on three points: esquid proxy server was configured to perform authentication process before allowing access to internet, therefore any clients that does not belong to the network would not be able to attend the network and access the internet. fby using ssh with hamachi, a secure vpn was set up between remote clients and the linux server. gby applying ssh with socks proxy, the internet traffic would go through a socks proxy. this supports the security by having data encryption. 6. references [1] m. sauter, “communication systems for the mobile information society”, isbn: 100470-0267-6 (hb), john wiley & sons, ltd, 2006. [2] a. mishra, “advanced cellular network planning and optimization 2g evolution to 4g”, isbn-13: 978-0-470-0147-4 (hb), john wiley & sons, ltd, 2007. mohammed a. abdalla al-khwarizmi engineering journal, vol. 8, no. 1, pp 1-10 (2012) 9 [3] j. eberspacher, h. vogel, c. bettstetter and c. hartmann, “gsm architecture, protocols and services”, 3 rd edition, isbn: 978-047030707(hb), wiley & sons, ltd, 2009. [4] a. jani, “general packet radio service (gprs)”, ieee potentials, vol. 21, no. 2, pp. 12-15, 2002. [5] t. sohus and p. nielsen, “analysis and model based optimization of tcp for wireless networks”, master thesis, distributed systems, department of control engineering, alborg university, denmark, 2003. [6] zinah j. ameen "wlan network based on gprs network" m.sc. thesis, al-nahrain university, college of information engineering 2011. [7] logmein, inc. "logmein hamachi2 security white paper" 2011. (2012 )1 10 ، صفحة1، العذد8مجلة الخوارزمي الهنذسية المجلذ محمذ احمذ عبذ هللا 10 بشكل آمنgprsدمج شبكة السلكية محلية مع شبكة *** زينة جعفر محمذ أمين ** خليفة عبود سالم * محمذ احمذ عبذ هللا جايعت انُٓزٌٍ / كهٍت ُْذست انًعهٕياث/ قسى ُْذست انًعهٕياث ٔ االحصاالث* جايعت بغذاد / كهٍت انُٓذست انخٕارسيً/ قسى ُْذست انًعهٕياث ٔاالحصاالث** انجايعت انخكُٕنٕجٍت / قسى ُْذست انحاسباث ٔحكُٕنٕجٍا انًعهٕياث*** mohammedalmushdany@yahoo.com :انبزٌذ االنكخزًَٔ khalifaabboud@yahoo.com :انبزٌذ االنكخزًَٔ zinahameen83@yahoo.com :انبزٌذ االنكخزًَٔ الخالصة . انخهٌٍٕت باسخخذاو يُفذ دخٕل يزبٕط انى يقسىgprsفً ْذا انبحث حى بُاء شبكت السهكٍت يحهٍت السخخذايٓا نهذخٕل انى االَخزَج يٍ خالل شبكت يثم انعَُٕت انًخغٍزة gprsَظزا ناليكاٍَاث انًحذٔدة انخً حٕفزْا شبكت. linuxحخى ادارة ْذِ انشبكت يٍ خالل خادو حى بزيجخّ باسخخذاو َظاو انخشغٍم ip حى اضافت خادو. باالضافت انى كٌٕ عزض انحشيت يحذٔد نذنك حى اضافت عذد يٍ انخقٍُاث نهخغهب عهى ْذِ انًححذاثdhcp نٍكٌٕ انًسٍطز انٕحٍذ حٍث ٌقٕو بخشٌ انصفحاث انخً حى اسخذعاؤْا فً proxy ٔنغزض حقهٍم اسخخذاو حشيت االَخزَج حى اضافت خادو . ipانذي ٌخى يٍ خالنّ حٕسٌع انعُأٌٍ جعم بااليكاٌ يشاركت nat كًا اٌ اضافت يخزجى انعُأٌٍ. ٔقج سابق نغزض االسخخذاو انالحق ٔ سٌادة سزعت انحصٕل عهى انبٍاَاث يٍ قبم انًسخخذو . نخذعٍى ايٍُت انُظاو sshَظزا نعذو سزٌت حبادل انبٍاَاث يٍ خالل شبكت االَخزَج نذنك حى اضافت بزٔحٕكٕل. َفس انعُٕاٌ يٍ قبم اكثز يٍ يسخخذو نهخُشٌم خالل َقطت 13.7kbps نهخحًٍم10.95kbps اظٓز االخخبار االٔل باٌ سزعت حُشٌم ٔ ححًٍم انبٍاَاث فً أقاث يخخهفت كاٌ بًعذل نالرسال ٔ kbps 143.3 حٍث ٔجذ باٌ يعذل سزعت انبٍاَاثproxyكًا اظٓز االخخبار انثاًَ باٌ اداء انشبكت قذ ححسٍ باضافت خادو . gprsأألحصال 376.6 kbps نالسخالو . mailto:mohammedalmushdany@yahoo.com%20������ mailto:mohammedalmushdany@yahoo.com%20������ mailto:khalifaabboud@yahoo.com mailto:zinahameen83@yahoo.com <4d6963726f736f667420576f7264202d20dac8c7d320e6e1edcb20e6c7d3d1c7c139322d203939> al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 14, no. 3, september, (2018) p.p. 9299 effect of carburization parameters on hardness of carburized steel using moora approach abbas khammas hussein* laith kais abbas ** asraa kareem hameed *** *,**,***department of materials engineering / university of technology/ baghdad/ iraq *email: abbas2000x@gmail.com **email: laithka2012@gmail.com ***email: sosaalmalky801@gmail.com (received 20 september 2017; accepted 26 february 2018) https://doi.org/10.22153/kej.2018.02.001 abstract in this research, (moora) approach based– taguchi design was used to convert the multi-performance problem into a single-performance problem for nine experiments which built (taguchi (l9) orthogonal array) for carburization operation. the main variables that had a great effect on carburizing operation are carburization temperature (oc), carburization time (hrs.) and tempering temperature (oc). this study was also focused on calculating the amount of carbon penetration, the value of hardness and optimal values obtained during the optimization by taguchi approach and moora method for multiple parameters. in this study, the carburization process was done in temperature between (850 to 950 ᵒc) for 2 to 6 hours. quenching was done for the specimens after heat treatments in furnace chamber by using different quench solutions, water, salt and polyvinyl alcohol. analysis of variances (anova) were performed for nine experiments in order to optimize the problem that was associated with multiple criteria (parameter) to achieve maximum hardness and depth penetration. the program results showed that the optimum conditions are carburization temperature (950 oc), carburization time (2 hrs.), tempering temperature (200oc), tempering time (10 hrs.), and activator (10 wt. %). furthermore, the best quenching media was the polyvinyl alcohol. keywords: anova, carburizing, hardness, moora, optimization, taguchi. 1. introduction alloys of iron and carbon are known as steel which their definite content of carbon with the range of (0.15-1.5 %) [1], steel alloys with low percentage of carbon have similarity properties of iron, as the percentage increase the metal acquires hardness and becomes stronger but less ductile [2], hardness is increased in the outer layer of metal surface by a series of processes known as case hardening and there are several methods of hardening one of them called carburizing, which is considered as a very important process and it is performed to steel surface hardening [3, 4]. stainless steel can be classified into three basic categories austenitic, ferritic and martensitic [5]. the crystals structure of steel can be determined by atomic arrangement. in general, there are two crystal structures of iron; one of them is bodycentered-cubic (bcc) and the other is the facecentered-cubic (fcc), the (fcc) atomic arrangement of structure have high solubility limit than a (bcc) structure, which belongs to the interstitial sites where carbon can sit between the iron atoms [6]. casting processes usually used to introduce the alloying elements to the steel [7]. surface hardening is a simple approach of hardening of the steel surface. this technique is used for low carbon steels, where the carbon is added to the external surface of the steel [8]. the process is generally done within austenitic range at temperature between (850-950 ºc) for mild abbas khammas hussein al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 9299 (2018) 93 steel in which at this temperature the carbon has a high solubility [9]. for a successful carburizing process done, three factors must be controlled very well (carburizing time, temperature and chemical composition) [10]. bulan abdullah et.al [11], studied the effect of paste carburizing treatment on hardness and tensile strength at different range of temperature (700 to 800 ºc) and holding time (6 hours). the formation of high carburized layer associated with temperature and the results showed an increase in temperature which lead to improvement of tensile strength and hardness. sorin adrian barabasi and adriana florescu [12], studied the hardness of (sae 3310) and (sae 4320) steels and clearly demonstrate an improvement in outcomes deep carburizing. a decrease in residual austenite content was observed and located on the surface of the piece after diffusion and spheroidization annealing, which leads to an increase the hardness. k. m. boubaker et.al [13], studied nondestructive inspection for characterizing carburized steel according to a theoretical model and experiments verifications using the optical beam deflection test. measurements focused on determining mechanical properties. k. palaniradja et.al [14], tried to study the behavior of the surface hardness according to carbon penetration depth in (sae 8620) and (aisi 3310) steel materials by using (taguchi (l9) array). the experiments showed that the observations are within a (95 %) condense level and conclude that the experimental result with a very low error, and hence (taguchi's) design can be used to optimize the process parameters of gas carburizing in order to achieve the desired properties for the specimens. “ravendra singh” [15], studied the mild steel carburized under different temperature ranges and investigated the suitable temperature at which the mild steel gives the best results for the hardness and wear mechanical properties by using (taguchi) approach. maikon a. birnfeld. et. al. [16], studied the residual stresses and surface roughness variations after shot peening and subzero treatment applied to carburize and quench (aisi p20) tool steel. in this research, the optimization is carried out using (moora) approach to optimize the required carburization process parameters for the best properties in carburized mild steel. anova (analysis of variance) was also applied to determine the effect of each parameter on the output i.e. hardness and penetration depth for mild steel. 2. experimental procedure table (1) shows the chemical composition for the sample of mild steel considered in this work. samples with diameter (10 mm) and length (30 mm) have been carburized. carburization is done for period of time and quenched with a different solution following by a tempering within different time according to the factor level shown in table (2). samples were cleaned with alcohol solution (ch3coch3) then embedded in carburization box that contains graphite up to (90 %) within activator (baco3) up to (10 %) then the box sealed with clay to prevent the undesirable reactions. the factors and levels selected for the (doe design of experiment) analysis are shown in table (2). the carburized samples are quenched with different solution (water solution, salt solution and polyvinyl alcohol solution) and the specifications of this solution are shown in table (3). table 1, chemical composition of mild steel sample (astm/e/415-14). elements % c % si % mn % p % s % ni % al % co % cu % nb average. contact 0.122 0.0005 0.442 0.0005 0.0269 0.0119 0.0052 0.001 0.0135 0.001 elements % w % ta % sn % zr % zn % cr % mo % ti % v % fe average contact 0.0056 0.0082 0.001 0.0064 0.0036 0.0097 0.001 0.0005 0.0009 rem abbas khammas hussein al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 9299 (2018) 94 table 2, factors and their levels of carburization. factor factor code levels 1 2 3 carburization temp. (oc) a 850 900 950 carburization time (hrs.) b 2 4 6 tempering temperature (oc) c 200 250 300 tempering time d 1 1.5 2 activator wt.% e 10 10 10 quench media f water brine polyvinyl alcohol table 3, characteristics of the used quenching medias. salt specification material percentage polyvinyl alcohol specification poly vinyl alcohol (pva): 99 % hydrolyzed (so4) 0.002 % concentration = 1.5 gm. /liter in distilled water (fe) 0.002 % (pb) 0.0005 % (k) 0.02 % impurity limit (1050 ˚c). 1.0 % grinding and polishing processes were applied for microstructure examination. grinding and polishing were carried out using (silicon carbides (sic) papers (320, 400, 600, 800, 1000, 1200)) followed by etching process by using (nital (2 % nitric acid & 98 % alcohol)) then the specimen is examined under microscope and the amount of depth penetration was then calculated, figure (1) shows microstructure of penetration for the carburized sample. fig. 1. microstructure of penetration for the carburized sample (1000x). the pyramid diamond is forced into the surface of the specimen and the ratio of the applied load divided by the pyramidal area of the indentation, determination of the vickers hardness (hv) is done according to the following equation: vhn = �.��� ��² …(1) where: p = amount of applied load (kg). d= represent the length of the diagonals impression [17]. the amount of applied load is (2.49 n (0.3 kg)). 2.1 moora approach multi-response optimization, also known as multi-performance optimization, is the process of optimizing two or more responses subjected to certain conditions. the mooraapproach was first discovered by “brauers” in (2004) which was a multiperformance optimization technique that can be effectively solve several types of complex problems related to multi-responses in many applications. the (multi-objective optimization on the basis of ratio analysis(moora)) approach starts with a decision matrix as expressed as follows [18]. d = 1 2 3⋮ � �� �1 �2�11 �12�21 �22 �3 … ���13 … �1��23 … �2��31 �32⋮ ⋮��1 ��3 �33 … �3�⋮ ⋱ ⋮��3 … ����� …(2) the procedure for using (moora) for ranking alternatives is: step 1: determine the normalized decision matrix by vector method as defined as follows: ���� = ����∑ ���� �!" …(3) where: i = 1,.., m ; j = 1,…, n. step 2: determine composite score as expressed in equation (4): #� = ∑ ����$�%� − ∑ ����'�%$(� …(4) abbas khammas hussein al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 9299 (2018) 95 where: )∑ ���� *$�%� and )∑ ���� *'�%$(� are benefit and non-benefit criteria, respectively and if there are responces more important than others, also (i = 1…. m), the composite score of these attributes become as expressed in equation (5): #� = ∑ +�����$�%� − ∑ +�����'�%$(� …(5) where: +� is the weight of )-./* criteria. step 3: rank the alternatives in descending order. figure (2) shows the flowchart of (moora) approach. fig. 2. flowchart of (moora) approach. 2.2 multi perform optimization multi-performance optimization is an area of multiple response criteria, which is concerned with multiple optimization problems which include several objective functions to be optimized simultaneously. in practical problems, there can be more than three objectives [19]. 2.3 signal-to-noise ratio (s/n): (s/n) ratio according to (taguchi) design method is a measure of robustness used to identify variability in a product or process by reducing the effects of noise factors and control factors. in (taguchi) design experiment, noise factors can be manipulated to force variability to occur and from the results, identify optimal control factor settings that robust, or resistant to variation from noise factors. the (s/n) ratio reassures how the response varies relative to the target value under different noise conditions [20]. 3. results and discussion the effective case depth is at a depth of about (4µm) where the surface hardness is approaching (300 hv). this is can be attributed to the nature of carburized case structure which can be martensitic or bainitic [21]. the experimental results were manipulated for case depth (carbon penetration depth). the microhardness results were analyzed using (moora) method. the results were feed into the (minitab) software to determine the corresponding (s/n) ratios. the analysis results are in table (5) and figure (3). it was found that the maximum value of microhardness reached at carbon penetration depth of (4 µm) which may attribute to the nature of factor settings for experiment (no. 4). fig. 3. means of (s/n) ratios. abbas khammas hussein al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 9299 (2018) 96 table 4, results of (moora) approach. the (moora) method was used to find out the best conditions or parameters for carburized steel and the results from table (4) and figure (3) shows that the optimum conditions are carburization temperature (950 oc), carburization time (2 hrs.), tempering temperature (200 oc), tempering time (10 hrs.), activator (10 wt. %) and quench media polyvinyl alcohol. metallographic examination is a powerful tool for the study of carburized steels and invaluable for diagnosing failures. in assessing the carbon penetration depth, metallographic are usually requested to measure the total carbon penetration depth or the effective carbon penetration depth. figure (4) illustrates typical microstructures of carburized steel specimens with varying carburizing process parameters according to (taguchi) array. this figure shows the influence of the ferratic that present in subsurface microstructure, which is effect on the microhardness value of carburized steel. depths of carbon start from surface towards core at values from (4.4938 m) to (8.242 m). anova analysis was used to analyze the effects of carburization temperature, carburization time, tempering temperature, tempering time, activator and quench media on hardness property. in this analysis, the percentage contributions of control factors were used to evaluate the corresponding effects on the performance characteristics. the performed experimental plan was evaluated at a (ɑ= 0.05 confidence level). according to the results of (anova) showed in table (6), tempering time had a dominant effect (24.63%) on the quality characteristics. this parameter was followed by tempering temperature with a ratio of (24.51%). exp. no microstructue 1 2 3 4 exp. no. case depth (µm) micro hardness (hv) normalization beneficial attributes s/n moora rank depth penetration micro hardness 1 5.4628 147.066 0.296644 0.271089 0.567733 -3.6 9 2 5.857 183.2 0.31805 0.337695 0.655745 -4.6 3 3 5.5408 154.333 0.30088 0.284484 0.585364 -1.1 8 4 5.5408 312.63 0.30088 0.576275 0.877155 -4.6 1 5 4.4938 186.8 0.244025 0.344331 0.588356 -4.5 7 6 4.646 185.533 0.25229 0.341996 0.594285 -3.8 6 7 7.4448 129.17 0.404272 0.238101 0.642373 -3.6 5 8 8.242 125.433 0.447562 0.231212 0.678774 -3.8 2 9 6.96 125.8 0.377946 0.231889 0.609835 -4.6 4 abbas khammas hussein al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 9299 (2018) 97 5 6 7 8 9 fig. 4. microstructures and penetration depth of carburized specimens according to (taguchi) array (1000x). table 6, anova table 4. conclusions moora-based taguchi’s design method can be used to determine the optimal carburization parameters for the carbon steel alloy studied in the paper. from the results, it was found that: 1. the (moora) method was applied to determine the most optimum conditions for carburizing process of steel and the results show that the optimum conditions are, carburization temperature (950 oc), carburization time (2 hrs.), tempering temperature (200 oc), tempering time (10 hrs.), activator (10 wt. %) and quench media polymer to get the optimum results for the carburizing. 2. based on (anova) method, the highly effective parameters on carburizing process are found as tempering time which had a dominant effect (24.63 %) on the quality characteristics and tempering temperature with a ratio of (24.51 %). 3. the results show that the hardness was greatly improved according to (taguchi) array. 5. reference [1] d. a. fadare, t. g. fadara and o. y. akanbi, "effect of heat treatment on mechanical properties and microstructure of (nst 37-2) steel", journal of minerals & materials characterization & engineering, vol. 10, no.3, pp: (299-308), 2011. parameter degree of freedom sum of square mean sum of square contribution (%) a 5 0.011 0.002 10.58 b 5 0.022 0.004 22.22 c 5 0.024 0.005 24.51 d 5 0.024 0.005 24.63 e 5 0.011 0.002 11.23 f 5 0.007 0.001 6.84 total 0.099 abbas khammas hussein al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 9299 (2018) 98 [2] d. gandy, "carbon steel ", handbook, electric power research institute, pp: (2-4), march, 2007. [3] a. clark, "comparison of tempering and quench and tempering processes for carburized automotive steels", m.sc. thesis submitted to university of windsor, 2013. [4] a. j. patel, s. n. chaudhari, “effect of different tempering temperatures and different load on wear behavior and mechanical properties on mild steel”, international journal of advance engineering and research development, vol. 2, issue 10, pp: (69-76), october, 2015. [5] william d. callister, “materials science and engineering”, university of utah, salt lake city pp: (325-326), 2007. [10] [6] c. m. méndez, m. m. covinich, a. e. ares, "resistance to corrosion and passivity of 316l stainless steel directionally solidified samples", in tech., cc by 3.0 license, book edited by m. aliofkhazraei, isbn: 978-95351-1223, http:// dx.doi.org/10.5772/57275, (2014). [7] o.s. fatoba1, o. l. akanji, a. s. aasa, "optimization of carburized uns g10170 steel process parameters using (taguchi) approach and response surface model (rsm)", journal of minerals and materials characterization and engineering, vol. 2, pp: (566-578), 2014. [8] j. gupta, “mechanical and wear properties of carburized mild steel samples”, mechanical engineering, m.sc. thesis submitted to the national institute of technology, rourkela, may, 2009. [9] e. santuliana, “effect of surface treatments on mechanical properties of low alloy sintered steels”, ph.d. thesis submitted to university of trenno -italy, april, 2011. [10] a. k. hussein, l.k. abbas, j. j. dawood and n.j. ismae, “modeling of carburization parameters process for low carbon steel”, eng. & tech. journal, vol. 34, part (a), no. 6, pp: (1069-1079), 2016. [11] bulan abdullah, s.k. aliasa, ahmed jaffara, syazuan abdul latipa, salmiah kasolanga, mohd faizul izhama, muhd azimin abd ghania, “mechanical properties of paste carburized astm a516 steel”, the malaysian international tribology conference, mitc, pp: (525530), 2013. [12] s. a. barabasi, a. florescu, “optimization of deep carburizing heat treatment”, international journal of information technology and business management, vol.32, no.1, pp: (23-28), december, 2014. [13] j. petrik, “the microhardness of heat treated carbon steel, department of integrated management”, metallurgical faculty, materials science (medžiagotyra). vol. 20, no. 1, pp: (21-24), 2014. [14] k. palaniradja, n. alagumurthi, v. soundararjan, “optimization of process variables in gas carburizing process: a taguchi study with experimental investigation on sae 8620 and aisi 3310 steels”, pondicherry engineering college, vol. 29, pp: (279-284), 2005. [15] r. singh, "investigation of optimal process parameters for mechanical and wear properties of carburized mild steel using taguchi approach”, int. j. eng. sci. adv. research, vol. 1, no. 1, pp: (90-92), march, 2015. [16] m. a. birnfeld, g. pintaúde, j. c. k. das neves, “effect of carburized steel hardness on surface roughness and residual stresses after manufacturing operations”, international congress of mechanical engineering, vol. 20, pp: (57-64), gramado, rs, brazil ,15-november-2009. [17] v.b. cassapi, “application of rock hardness and abrasive indexing to rock excavating equipment selection”. phd thesis, submitted to university of nottingham, (1987). [18] k. genel, m. demirkol, “effect of case depth on fatigue performance of aisi 8620 carburized steel”, international journal of fatigue, vol. 21, pp: (207–212), 1999. [19] w. karel, m. brauers, e. k. zavadskas, “the moora method and its application to privatization in a transition economy”, control and cybernetics, vol. 35, no. 2, pp: (207-212), 2006. [20] h. singh, “taguchi optimization of process parameters: a review and case study”, international journal of advanced engineering research and studies eissn2249–8974, vol. 1, issue 11, apriljune, pp: (39-41), 2012. [21] f. george. v. voort, f. gabriel, m. lucas, “microstructural characterization of carburized steels”, heat treating progress, 4 edt september, 2009. )2018( 92-99، صفحة 3د، العد14دجلة الخوارزمي الهندسية المجلمعباس خماس حسين 99 دراسة تأثير الكربنة على صالدة الفوالذ المكربن بأستخدام طريقة مورا *اسراء كريم حميد **ليث قيس عباس ***عباس خماس حسين التكنولوجيةالجامعة /ة الموادقسم هندس*،**،*** x@gmail.com2000abbas: البريد االلكتروني* gmail.com2012laithka@: البريد االلكتروني** gmail.com801sosaalmalky@: البريد االلكتروني*** الخالصة تصميم تاكوجي في تحويل مشكلة متعددة االداء الى مشكلة واحدة االداء لتسعة تجارب والتي تستخدم في –أستخدام منهج (مورا) تم في هذا البحث ووقت ،˚)درجة حرارة الكربنة ( س و) المصفوفة المتعامدة) لعملية الكربنة. المتغيرات االساسية كان لها تاثير كبير على عملية الكربنة l9(تاكوجي ( وركزت ايضا على حساب كمية عمق الكربون، وقيمة الصالدة وتم الحصول على القيم المثلى من خالل نهج ˚). الكربنة (ساعات). ودرجة حرارة التلدين (س ٦الى ٢) لمدة (درجة مئوية ٩٥٠الى ٨٥٠(تاكوجي) و (مورا) لمعطيات متعددة. في هذة الدراسة، تم اجراء عملية الكربنة في درجة حرارة بين ( طة محاليل تقسية مختلفة (الماء والملح والبوليمر). تم ادخال نتائج التجارب في اساعات). التقسية حصلت للعينات بعد المعاملة الحرارية في الفرن بوس من الصالدة وعمق االختراق. واظهرت برنامج (انوفا لتحليل الفروق) من اجل تحسين المشكلة التي تربط معاير متعددة (المعطيات) لتحقيق اقصى قدر درجة ،درجة مئوية) ٢٠٠درجة حرارة التلدين ( ،درجة مئوية)، زمن الكربنة (ساعتان) ٩٥٠نتائج البرنامج أن الظروف المثلى هي درجة حرارة الكربنة ( مر.بالوزن) وافضل وسائل التبريد كانت وسائل التبريد بالبولي %١٠المنشط (، ساعات) ١٠الحرارة ( اصلان صباح الدين12-1 al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 7, no. 3, pp 1 12 (2011) steady state performance investigation of a three phase induction motor running off unbalanced supply voltages aslan sabahaldeen jalal abdi department of mechatronics engineering/ al-khwarizmi college of engineering/ university of baghdad email: aslannabdi@yahoo.com; aslan.kecbu@uobaghdad.edu.iq (received 17 february 2011; accepted 20 jun 2011) abstract the objective of this work is to investigate the performance of a conventional three phase induction motor supplied by unbalanced voltages. an effort to study the motor steady state performance under this disturbance is introduced. using per phase equivalent circuit analysis with the concept of symmetrical components approach, the steady state performance is theoretically calculated. also, a model for the induction motor with the matlab/simulink sps tools has been implemented and steady state results were obtained. both results are compared and show good correlation as well. the simulation model is introduced to support and enhance electrical engineers with a complete understanding for the steady state performance of a fully loaded induction motor operating from unbalanced supply voltages. keywords: three phase induction motor, unbalanced supply voltage, matlab/simulink. 1. introduction for industrial and mining applications, three phase induction motors (im) are the prime movers for the vast majority of machines. these motors can be operated either directly from the mains or from variable frequency drives. in modern industrialized countries, more than half of the total electrical energy used in those countries is converted to mechanical energy through ac induction motors. in the last decade, using three phase squirrel cage ac induction motors (im) with ac variable speed drives has increasingly become a common practice. since the 1980's, the popularity of the variable speed drives has grown rapidly, mainly due to advances in power electronics and digital control technology affecting both the cost and performance of this type of speed control. to clearly understand how the variable speed drive system works, it is necessary to understand the principles of operation of this type of motor. the most popular analytical method that has been used in analyzing the ims is the equivalent circuit method [1-4]. to understand the performance of an im operating from unbalanced supply voltages, it is useful to electrically represent the motor by an equivalent circuit [5]. it is worth mentioning that the nema standard recommends that the voltage deviation from the motor rated voltage not exceed ±10% at the rated frequency [6]. computer models and simulation tools have been extensively used to support and enhance electric machinery courses. matlab with its toolboxes: simulink [8] and simpowersystems [9] is one of the most popular software packages used to investigate the transient and steady-state characteristics of electric machines [10 – 13]. ayasun and nwankpa [14] had presented simulation models of induction motor tests performed to obtain parameters of the per-phase equivalent circuit of three-phase induction motors. the results imply that matlab/simulink is a good simulation tool to model induction motor tests and to evaluate its steady – state characteristics. however, the reported results do not discuss the effect of unbalanced supply voltage on the induction motor steady – state characteristics. mailto:aslannabdi@yahoo.com mailto:aslan.kecbu@uobaghdad.edu.iq aslan sabahaldeen jalal abdi al-khwarizmi engineering journal, vol. 7, no. 3, pp 1 12 (2011) 2 j. d. kueck, et. al, [15] have reported that current unbalances produced by relatively small voltage unbalances appear to be a serious concern in susceptible motors if they are operated with a small or no service margin. unbalance can be due to either unbalance in the motor itself or unbalance in the power supply due to unbalance in voltage magnitudes or phase angles or level of harmonic distortion between phases. in their particular case, impedance measurements at the motor terminals have been carried out. this is determined by measuring the impedance between each of the three winding terminals immediately after the motor was de-energized from continuous operation at room temperature and left to cool to room temperature. these three values are averaged and the maximum deviation from the average is expressed in percent. measurements over 4 months revealed impedance unbalance growing up with time as it varied from 5.6% up to 8%. regardless of the source of the unbalance, unbalanced voltages result in negative sequence currents which cause additional motor heating, unbalanced forces, and reduction in speed. the reported results were obtained regarding the effect of unbalanced voltage levels from 0 to ±4%. in iraq, with the existing poor power grid, the per phase average unbalanced voltage levels are from 4.6% to 16%, and the voltage is always below the nominal level, as will be explained later. one of the most effective causes of this voltage unbalance is that a combination of single phase and three phase loads on the same distribution system, with the single phase loads unequally distributed. the first object of this work is to analyze the three phase induction motor supplied by low imbalance voltages using the concepts of symmetrical components and equivalent circuit methods. the second object is to introduce matlab/simulink model representing the steady state operation of three phase induction motor running off unbalanced supply voltages. the reason that matlab, with its sps toolboxes, was selected to model the induction motor is that it is the main software package that has been used by almost all engineers graduated from the author’s institution as a computation tool to reinforce electrical and mechatronic engineering education. therefore, engineers can easily access matlab, and they already have the basic programming skills to use the given simulink models and to write computer programs when required for selecting an induction motor for an application. 2. mathematical model 2.1. basic steady state equivalent circuit with balanced supply voltages [1 – 5] the performance of the three phase im with a cage rotor can be analyzed with the equivalent circuit method at different stages of its operation. the equivalent circuit is drawn on per phase basis, as shown in figure (1). at standstill, the im acts like a transformer. the produced traveling field due to three phase stator currents induces emfs in both the stator and rotor windings of frequency ω1 as e1 and e2s, respectively. as the motor speeds up, the rotor emf frequency diminished and becomes ω2, where (ω2 = s ω1). following the same procedure described in reference [5], figure (2) represents the per phase equivalent circuit of an im with the rotor circuit reduced to the stator circuit. in figure (2), there is only one frequency, the stator frequency ω1, which means that they refer to an equivalent rotor at standstill, but with an additional “virtual” rotor resistance per phase rr '(1/s−1) dependent on slip (speed). fig.1. three phase im equivalent circuit on per phase basis. fig.2. three phase im equivalent circuit on per phase basis reduced to stator circuit. it is evident that the active power in this virtual resistance is in fact the electromechanical power of the actual motor, where ( )2rrm i1 s 1r3p ′      −′= (watts) …(1) aslan sabahaldeen jalal abdi al-khwarizmi engineering journal, vol. 7, no. 3, pp 1 12 (2011) 3 hence, the electromagnetic torque (power) which crosses the air gap from stator to rotor may be obtained, as ( ) 1 2 3 ω.s irt rr e ′′ = (synchronous watts) … (2) a definition for the slip is introduced by equation (3) as; ( ) e cur e rr p p .t irs = ′′ = 1 2 3 ω …(3) equation (3) signifies that, for a given electromagnetic power (torque), for a given frequency, the slip is proportional to rotor winding copper losses. at ideal no – load im operation, the input (active) power is dissipated into electromagnetic loss, fundamental and harmonics stator core losses, and stator windings and space harmonics rotor core and cage losses. these losses may be combined in a resistance r1m in parallel with a magnetizing leakage reactance x1m, as in figure (2). r1m may be calculated from the no – load operation of the im with the required no – load measurements including the reactive input power. figure (3) shows the per phase equivalent circuit of an im running at no – load with the rotor circuit omitted as its copper losses are neglected, ( ≈' ri 0). fig.3. im equivalent circuit on per phase basis running at no –load with the rotor circuit omitted. the relation between the resistance r1m and the magnetizing mutual leakage reactance x1m may be presented as; 0 m1 m1 k x r = …(4) the constant (k0) is to be calculated, repeatedly, from the no-load readings at different supply voltage (vs) and frequency. 2.2. steady state characteristics with unbalanced supply voltages polyphase ims are designed to operate most effectively at their nameplate rated voltage. most motors will operate satisfactorily over (±10 %) voltage variation [6]. deviations from the nominal motor design voltage can have marked effects on the motor performance. voltage unbalance can be more detrimental than voltage variation to motor performance and motor life. in general, ims should be designed (thermally) to stand ±10% voltage variation around the rated value, according to the standards of the nema. steady state im performance with unbalanced supply voltages may be treated by the method of symmetrical components [7]. the three-wire supply voltages va, vb and vc are decomposed into zero sequence, forward (+ve) sequence and backward (-ve) sequence components. this can be written in matrix form as;                     =           − + c b a v v v . aa aa. v v v 2 2 0 1 1 111 3 1 …(5) with the constant (a) given as 3 2 01201 πj ea =∠= …(6) a similar transformation is obtained for each phase current, and is given as                     =           − + c b a i i i . aa aa. i i i 2 2 0 1 1 111 3 1 …(7) thus, beginning with forcing the voltages va0, vb0, and vc0 to have equal magnitude and phase, the zero sequence component of each phase voltage are all defined by a single magnitude and a single phase angle, v0. secondly, by forcing the voltages va+, vb+, and vc+ to form a balanced three phase set with forward (+ve) phase sequence. this set of balanced voltages is responsible for producing the forward traveling field in the im. finally, forcing the voltages va−, vb−, and vc− to form a balanced three phase set with backward (-ve) phase sequence. similar sets aslan sabahaldeen jalal abdi al-khwarizmi engineering journal, vol. 7, no. 3, pp 1 12 (2011) 4 can be obtained for the current (stator or rotor current). it is worth mentioning that the zero sequence voltage component has almost negligible loss effect on the motor steady state performance. this is due to the fact that its current magnitude is very small in comparison with that of the positive sequence component, i0 ≈ 0. the unbalanced supply voltages may now be represented in terms of their symmetrical components, with vf = v+ and vb =v−, as      ++= ++= ++= cbcfcc bbbfbb abafaa vvvv vvvv vvvv 0 0 0 … (8) thus, applying equation (5) to obtain the forward and backward voltage components of phase (a), as ( ) ( )     ++= ++= cbaab c 2 baaf vavavv vavav 3 1v 2 3 1 …(9) noting that phases (b & c) forward and backwards voltage components are obtained as:     == == abcbafcf abbbafbf vav;vav vav;vav 2 2 …(10) as in single phase im, the slip for the forward component is (sf = s), while for the backward component the slip is (sb =2 – s). now, according to equation (9), we have two per phase equivalent circuits with the first one for the forward (+ve) sequence voltage component and the second for the backward (-ve) sequence voltage component, as shown in figures (4 & 5) respectively. fig.4. im per phase equivalent circuit supplied by forward sequence voltage component. fig.5. im per phase equivalent circuit supplied by forward sequence voltage component. the torque expression contains two components, and is given as; ( ) ( )         − ′′ − ′′ = s ir s irt rbrrfr e 2 3 22 1ω (n.m) …(11) due to the presence of the backward torque, the resultant torque will have an oscillating steady state value with a frequency of approximately twice the supply frequency. this, in turns, will cause a vibration in the im operation [15]. as a consequence, the im exhibits unscheduled service and maintenance time, especially for its bearings. the motor percentage efficiency (%η) in terms of power flow, for balanced supply voltages, is given as: powerelectricalinput powershaft% =η %100 pfiv3 t phph m × ⋅⋅⋅ ω⋅= …(12) in case of unbalanced supply voltages, and with the presence of the backward (braking) torque, the motor efficiency can be obtained by making use of equations (11&12), as; ( ) [ ] %100 ivivre3 s1t% * abab * afaf 1e × +⋅ ω−=η …(13) afi and abi are obtained using the equivalent circuits shown in figures (4 & 5). also, they can be obtained by making use of (7) with the stator current calculated from the basic equivalent circuit with three different unbalanced phase voltages. for calculations with a reference base for the unbalanced supply voltages, the percentage aslan sabahaldeen jalal abdi al-khwarizmi engineering journal, vol. 7, no. 3, pp 1 12 (2011) 5 voltage unbalance index (%vunb) is introduced. this index may be defined as: % % v vv ave max unb 100×= ∆ …(14) where: minmaxmax vvv −=∆ and: ( ) 3 cba ave vvvv ++ = 3. matlab/simulink models 3.1. im parameters data and simulation model implementation the im parameters data are listed in table 1. all parameters are referred (reduced) to the stator circuit. these data were used in both theoretical and simulation calculations. the three phase im is implemented using the induction machine block in the machine library of the sps. the electrical inputs of the induction machine are the three electrical connections of the stator (terminals a-bc), while the electrical outputs (terminals a-b-c) are the three electrical connections of the rotor. the rotor terminals disappear in cage rotor type selection. the input block (terminal tm) is the mechanical load torque at the machine’s shaft. table 1, im parameters used in the simulink model [8]. present model: 5.4 hp, 400 v, 50 hz, 1430 rpm parameter symbol type/ value rotor type --squirrel cage stator resistance, ω/ph rs 1.405 stator leakage inductance, h/ph ls1 0.005839 rotor resistance referred to stator, ω/ph rr ' 1.395 rotor leakage inductance referred to stator, h/ph lr1 ' 0.005839 magnetizing mutual inductance, h l1m 0.1722 pole pairs pp 2 combined machine and load inertia coefficient, kg.m2 j 0.0131 viscous friction coefficient, n.m×s) f 0.002985 the output terminal of the induction motor block (terminal m) allows for the measurement of several variables, such as speed and electrical torque. other different parameters of the im are specified using the induction machine-block dialog box. the supply voltage is implemented using the ac voltage source block. the parameters of each phase voltage (amplitude, phase angle and frequency) can be varied within their dialog boxes. all other circuit measuring and display units with the in between blocks are drawn from the different branches of the sps toolboxes. 3.2. no-load simulation model figure (6) depicts the sps/simulink implementation for the three phase im steady state no – load operation with nominal (rated) balanced supply voltages and a nominal frequency of 50 hz. the purpose of this run is to calculate the resistance r1m which its value will be used in theoretical calculations. the calculated value of this resistance is found to be (4126 ω). since the value is too high in comparison with x1m, r1m value may be neglected in performing the theoretical calculations. 3.3. im operation supplied by unbalanced supply voltages simulation model the power grid supply voltages that supply an industrial region are measured and recorded. the phase voltages of the power supply at alzaffarania industrial territory in baghdad are listed in table 2, with the corresponding date and time. according to these readings, the simulation results have been obtained and compared with theoretical ones. figure (7) depicts the simulink/sps implementation for the three phase im steady state operation with unbalanced supply voltages and with a nominal frequency of 50hz. table 2, three phase supply voltage readings at alzaffarania industrial region. time date va (r.m.s value), v vb (r.m.s value), v vc (r.m.s value), v 10:30 am 8/7/2010 188.5 196 202 11:40 am 5/8/2010 185 195.7 198.2 12:50 pm 19/1/2011 204 207 218 aslan sabahaldeen jalal abdi al-khwarizmi engineering journal, vol. 7, no. 3, pp 1 12 (2011) 6 fig.6. im no-load steady state operation with balanced supply voltages and nominal frequency. fig.7. im simulation model steady state performance results with unbalanced supply voltages & full load condition. aslan sabahaldeen jalal abdi al-khwarizmi engineering journal, vol. 7, no. 3, pp 1 12 (2011) 7 4. results the equivalent circuit method described in section (2, section 2.2) is used to obtain the theoretical calculations, with the im data listed in table 1. also, with the motor assumed to operate with full load condition, the simulation was carried out, and results were obtained. for comparison purposes, table 3 shows the assumed unbalanced supply voltages at nominal frequency with the results obtained using theoretical calculations. their corresponding values obtained from the im simulation model are listed, too. the maximum percentage deviation between the results is with a maximum amount of 2.05 %, which gives a good agreement for predicting the steady state im characteristics with both methods. regarding the im efficiency, the theoretical results are higher than those obtained with the simulation. this is due to the fact that in theoretical calculations the fundamental core losses are neglected (r1m is too high) with the mechanical losses, whereas these losses are represented in simulation model by the viscous friction coefficient. figures (8 & 9) show, respectively, the simulink results of the variation of both the electromagnetic torque and speed with time. from the figures, it is clear that the unbalanced supply voltages cause the ripple in both the torque and speed waveforms, due to the presence of the backward, (-ve) sequence component, torque. table 3, theoretical and simulation results for the im model under investigation. assumed unbalance supply voltages 0 a 0262v ∠= ; 0 b 120283v −∠= ; 0 c 120311v ∠= theoretical results simulation results % deviation slip 0.06 0.05967 0.55 % efficiency 80.01 79.29 0.8999 electromagnetic torque, n.m 26.517 27.072 2.05 ripple in speed ( n∆ ), r.p.m. --20 -- ripple in electromagnetic torque ( et∆ ) --16.72 -- fig.8. electromagnetic torque variation of im running off unbalanced supply voltages. aslan sabahaldeen jalal abdi al-khwarizmi engineering journal, vol. 7, no. 3, pp 1 12 (2011) 8 fig.9. speed variation of im running off unbalanced supply voltages. figures (10 & 11) show the per unit efficiency variation (reduction) due to unbalanced voltage that occurs in single – phase and two – phases of the supply voltage, respectively. from the figures, it is clear that the unbalanced supply voltages cause the efficiency to be reduced as the voltage unbalance index increases, due to the presence of the negative sequence losses in stator / rotor circuits with its corresponding backward torque. the theoretical results are well correlated with the simulation results as shown in these figures. figures (12 & 13) show the variation of the electromagnetic torque ripple due to unbalanced voltage that occurs in single – phase and two – phases of the supply voltage, respectively. it is clear that the torque ripple increases with the unbalance index which is most effective with single – phase unbalanced voltage rather than the two – phase unbalanced voltage. figures (14 & 15) show the variation of the speed due to unbalanced voltage that occurs in single – phase and two – phases of the supply voltage, respectively. figures (16 & 17) show the variation of the speed ripple due to unbalanced voltage that occurs in single – phase and two – phases of the supply voltage, respectively. although the effect of single – phase unbalance is dominant on the speed ripple, the motor speed is greatly affected by the two – phase unbalance in comparison with single-phase unbalance. fig.10. per unit efficiency variation with 1– phase unbalanced voltage. fig.11. per unit efficiency variation with 2– phase unbalanced voltages. aslan sabahaldeen jalal abdi al-khwarizmi engineering journal, vol. 7, no. 3, pp 1 12 (2011) 9 fig.12. electromagnetic torque ripple variation with 1– phase unbalanced voltage. fig.13. electromagnetic torque variation with 2– phase unbalanced voltages. fig.14. speed variation with 1– phase unbalanced voltage. this can be attributed to the fact that the backward rotor current component and its corresponding torque produced by two-phase unbalance have less frequency, and hence long time duration, than that caused by single-phase unbalance. as a consequence, the resulting torque and its corresponding ripple will be less affected by two-phase unbalance, as clearly shown in figures (12 & 13). fig. 15. (speed variation with 2– phase unbalanced voltages). fig. 16. (speed ripple variation with 1– phase unbalanced voltage). fig. 17. (speed ripple variation with 2– phase unbalanced voltages). figures (18 & 19) show the steady state stator phase currents variation with the unbalanced voltage that occurs in single – phase and two – aslan sabahaldeen jalal abdi al-khwarizmi engineering journal, vol. 7, no. 3, pp 1 12 (2011) 10 phases of the supply voltage, respectively. with single – phase unbalanced voltage, the phase that lags the lowest phase has to withstand the current unbalances and supplies the most current for both the negative and positive sequences. this is clear in figure (18) with phase (b) current. with two – phase voltage unbalance, the leading phase with respect to the phase having the lowest voltage has to withstand the current unbalances. this is clear in figure (19) with phase (c) current. fig.18. steady state stator phase currents variations with 1– phase unbalanced voltage. fig.19. steady state stator phase currents variations with 2– phase unbalanced voltages. if the supply phase voltages and currents are measured, this is a good indication for knowing the voltage sequence and the unbalance type. for both unbalances, as a phase current is increased, an extra heat will be generated in both the stator and the rotor of the im. in addition, the large unbalance of the stator currents will result in nonuniform temperatures in the motor windings, and an overall motor heat rise. 5. conclusions three phase voltages supplied to an important industrial region in baghdad-iraq have been measured and tabulated at different times and dates. the voltages measuring dates and times are chosen as the power grid is subjected to heavy loads. with our poor distribution system, it is found that the absence of unbalanced supply voltages is almost impossible. this is due to many reasons, with uneven distribution of single – phase loads on the three phase power grid system as an important reason. in this work, the effect of the unbalanced supply voltage on the performance of a conventional three phase induction motor has been introduced. the analysis of 3 – φ, 5 hp, cage rotor im running off unbalanced supply voltages has been presented. modeling of the im using matlab/simulink sps tools has been introduced. the effect of unbalanced supply voltages on the im steady state performance has been investigated. both theoretical and simulink model results correlate well, with a maximum deviation of 2.05%. the reported results clarify that unbalanced voltages cause appreciable ripple in both the torque and speed of the induction motor. also, reduction in motor speed and efficiency results as the voltage unbalance index increases. considering the most important im steady state performance indices that are ripple free torque speed characteristics, and the high efficiency with full load condition, the presence of the negative sequence voltage component destroys, directly, these indices. also, both single – phase and two – phase unbalanced voltages result in higher stator currents. as a consequence, unbalanced heating of stator windings results, an overall rise in motor temperature and production of unbalanced forces on the motor bearings occur. this, in turns, directly affects the motor life time with the requirements of unscheduled motor maintenance. this would appear to be of a serious concern, especially with the motors that operate with small or no service margins. list of principal symbols s slip sf forward slip sb backward slip e1 stator emf induced, v/phase aslan sabahaldeen jalal abdi al-khwarizmi engineering journal, vol. 7, no. 3, pp 1 12 (2011) 11 e2s rotor emf induced, v/phase ir rotor phase current, a i' rb backward component rotor phase current referred to stator, a i' rf forward component rotor phase current referred to stator, a is stator phase current, a lr per phase rotor leakage inductance, h ls per phase stator leakage inductance, h pcur rotor winding copper losses, watts pelm rotor electromagnetic power, watts pm electromechanical power, watts pp air gap traveling field spatial pole pairs rr per phase rotor resistance, ω rr' per phase rotor resistance, ω rs per phase stator resistance, ω r1m resistance representing the core loss, ω te electromagnetic torque, n.m v0, v+, v zero, positive and negative voltage components, v va, vb, vc three phase supply phasor voltages, v vs per phase stator applied voltage phasor, v x1m magnetizing leakage reactance, ω greek letters η efficiency ω equal to 2πf 6. references [1] v. k. mehta and rohit mehta, principles of electrical machines, 2nd edition, s. chand & company ltd., nd, 2009. [2] m. n. bandyopadhyay, electrical machines: theory and practice, prentice-hall of india, n. delhi, 2007. [3] stephen j. chapman, electric machinery fundamentals, 4th edition, mcgraw-hill, inc., 2004. [4] m. barnes, variable speed drives and power electronics, newnes, 1st edition, gb, 2003. [5] i. boldea and s. a. nasar, the induction machine handbook, crc press llc, 1st edition, 2002. [6] nema standards publication no. mg 11993, motors and generators, published by the national electrical manufacturer's association. [7] l. l. grigsby, electric power engineering handbook, crc press llc, 2nd edition, 2006. [8] simulink, model-based and system-based design, using simulink, mathworks inc., natick, ma, 2000. [9] simpowersystems for use with simulink, users guide, mathworks inc., natick, ma, 2002. [10] m. h. nehrir, f. fatehi, and v. gerez, computer modeling for enhancing instruction of electric machinery, ieee trans educ., vol. 38 (1995), 166 – 170. [11] w. m. daniels and a. r. shaffer, reinventing the electrical machines curriculum, ieee trans educ., vol. 41 (1998), 92 – 100. [12] k. l. shi, t. f. chan, y. k. wong, and s. l. ho, modeling and simulation of the three-phase induction motor using simulink, ijeee vol. 36 (1999), 163 – 172. [13] s. ayasun and c. o. nwankpa, transformer tests using matlab/simulink their integration into undergraduate electric machinery courses, com. app. eng. educ., vol. 14 (2006), 142 – 150. [14] s. ayasun and c. o. nwankpa, induction motor test using matlab/simulink and their integration into undergraduate electric machinery courses, ieee tr. educ., vol. 48 (2005), 37 – 46. [15] j. d. kueck, d. a. casada and p. j. otaduy, a comparison of two energy efficient motors, ieee trans. ec, vol. 13, no. 2, june 1998, 140 – 147. )2011( 1 12 ، صفحة3، العدد 7مي الھندسیة المجلد مجلة الخوارز آصالن صباح الدین جالل 12 حرك الحثي التقلیدي ثالثي األطوار عندماالتحقق من خواص الحالة المستقرة للم الفولتیات) متوازن(یغذى من مصدر غیر متساوي آصالن صباح الدین جالل عبدي جامعة بغداد/ كلیة الھندسة الخوارزمي/ قسم ھندسة المیكاترونكس aslan.kecbu@uobaghdad.edu.iq; aslannabdi@yahoo.com: البرید االلكتروني الخالصة . المصدر یاتتلفولساوي القیم العظمى تیجھز من المصدر مع عدم عندما ھو دراسة خواص المحرك الحثي التقلیدي ثالثي األطوار إّن ھدف ھذا العمل تم دراسة , أیضا.ألغراض التحلیل النظري مفھوم المكّونات المتماثلةة للطور الواحد ودائرة المكافئالتحلیل یقةخدام طرإستتم ،ضطربمع ھذا المجھز الم المقارنة بین نتائج منظومة ). matlab(خواص الحالة المستقرة للمحرك في حالة الحمل التام بتمثیل المحرك بإستخدام نظام المحاكاة الموجودة في برنامج ال رك للحالة محاكاة ونتائج التحلیل النظري ھي الحكم في تأكید الطریقة النظریة المستخدمة، و تأكید أنموذج المحاكاة الذي بني إلستقراء خواص المحال .المصدر ألداء المحرك تحت ھذا اإلضطراب المجھز منالمھندسین الكھربائیین فھم و إستیعاب لدعم وتحسین بني نموذج المحاكاة إإّن .المستقرة mailto:aslan.kecbu@uobaghdad.edu.iq mailto:aslannabdi@yahoo.com سرمد عماد ابراهيم90-78 al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 7, no. 1, pp 78 – 90 (2011) على بعض الخواص ) zro2(والزركونیا ) al2o3(دراسة تأثیر إضافة دقائق كل من االلومینا )al-si-mg(المیكانیكیة لمتراكبات ذات أساس من سبیكة حسین إبراھیم دسرمد عما الجامعة التكنولوجیة/ قسم ھندسة المواد srmade@yahoo.com: االلكتروني البرید ) (receive 23 november 2010; accepted 2 june 2011 الخالصة وھمـا دقائق االلومینا بحجـم ) (al si mgیرامیكیـة في الخواص المیكـانیكیـة لسبیكـة یتنـاول البحـث دراسـة تأثیـر إضافـة نوعیـن مـن المـواد الس بنسب وزنیة وإضافتھا إلى السبیكة )20µm>p.s≥0.1µm( ودقائق الزركونیا بحجم حبیبي یتراوح بیـن) 0.1μm 20μm>p.s≤(حبیبـي یتراوح بیـن )0.2 ,0.4 ,0.6 ,0.8and 1% .(باكة بالمزج في تصنیع المادة المتراكبة باستخدام تقنیة الدوامة والتي تعمل على سحب الدقائق إلى داخل طریقة السب توتم والتعتی ق االص طناعي عن د ) (c˚520وتم بعد ذلك إجراء المعاملة المحلولیة للعینات عند درجة ح رارة . المنصھر المعدني وتوزیعھا خاللھ بشكل متجانس ت م ). (8hrحیث لوحظ أن قیم الصالدة للسبیكة األساس تزداد مع مدة التعتیق لتصل إلى أعلى قیمة لھا عند م دة . رات مختلفةفي فت) (c˚170درجة حرارة للنم اذج المعامل ة المتمثلة بفحص الشد والصالدة والبلى عند قیم الصالدة العظمىو المنتجة إجراء الفحوصات المیكانیكیة للسبیكة األساس والمادة المتراكبة وان الزیادة الحاصلة في قیم الصالدة للسبیكة المقواة بدقائق االلومینا اكبر ).%1(ولغایة حیث وجد ان قیم الصالدة تزداد مع زیادة النسب المضافة. حراریُا أعلى مما ھي علیھ في السبیكة األساس أما نتائج فحص الشد فقد بینت ان مقاومة الشد والخضوع للمادة المتراكبة. المقواة بدقائق الزركونیا قیم الصالدة من ثم تسلك سلوكًا مغ ایرًا لكنھ ا تبق ى محافظ ة عل ى ق یم أعل ى مم ا ھ ي علی ھ ف ي ) (%0.6وتزداد ھذه القیم مع زیادة النسب الوزنیة للدقائق المضافة والى حد وان الزیادة الحاصلة . اضھا مع زیادة النسب الوزنیة للدقائق المضافةفي حین تنخفض قیم المطیلیة مقارنة مع السبیكة األساس ویزداد انخف, السبیكة األساس في حین أن قیم المطیلیة للسبیكة المقواة بدقائق . في قیم مقاومة الشد ومقاومة الخضوع للسبیكة المقواة بدقائق االلومینا اكبر من تلك المقواة بدقائق الزركونیا وان , كما أدى إضافة دقائق الزركونیا وااللومینا إلى تقلیل معدل البلى للسبیكة األساس مع تغیر الحمل المس لط . ناالزركونیا اكبر من المقواة بدقائق االلومی أثبت ت .وان النقصان الحاصل في قیم معدل البلى للسبیكة المقواة بدقائق االلومینا اكبر من المقواة بدقائق الزركونیا. النقصان یزداد مع زیادة النسب المضافة ف ي ك ل م ن الس بیكة األس اس والم ادة المتراكب ة بینم ا أدت المعامل ة الحراری ة إل ى ظھ ور ) (alfesiت ائج فح ص األش عة الس ینیة ظھ ور الط ور الث انوي ن ال دقائق فض ًال ع ن ظھ ور , سن واضح فـي الخ واص المیكانیكی ـة التي أدت إلـى تحولسبیكة األساس ل البنیة المجھریة في) (mg2siو ) ( mg2alاألطوار والتي كان ت بش كل حبیب ات ناعم ة ومتجانس ة نوع ٌا م ا مقارن ُة بكب ر الحبیب ات ف ي البنی ة المجھری ة للس بیكة لمادة المتراكبةل المجھریة بنیةالالسیرامیكیة في .االساس .اختبار البلى ، اختبار الشد، الحشوات السیرامیكیة، المواد المتراكبة :المفتاحیة لكلماتا دمة المق .١ ذي ش ھده الع الم ف ي كاف ة نتیج ة للتط ور الص ناعي الكبی ر ال سعى العلماء والباحثون إلى أیجاد بدائل مختلف ة للم واد , المجاالت حی ث تحت اج العدی د م ن , ت االس تخدامات الص ناعیة المتع ددة ذا التطبیقات الھندسیة إلى مزیج من الخواص المالئمة الت ي ال یمك ن كالس بائك والل دائن ( اد الھندسیة األساسیة الحصول علیھا من المو ومن أھم ھذه الخواص ھي المقاومة النوعی ة العالی ة ) والسیرامیك ومعامل المرونة النوعي العالي والجساءة العالی ة والمتان ة وقابلی ة .[1]التشكیل أن التط ورات رك زت ومن ذ عق د الس بعینات ص وب األلمنی وم اس ع ف ي ش تى المج االت وس بائكھ كم واد أس اس وعل ى نط اق و اذ یعد من أوسع المع ادن الالحدیدی ة اس تعماًال , المدنیة والعسكریة وتع د س بائك األلمنی وم . النھ الثاني بعد الصلب استھالكا في العالم من السبائك المھمة جدا لما لھا من استعمال واس ع ف ـي العدی د م ن ككثافتھ ا حقول التكنولوجیا وذل ك المتالكھ ا العدی د م ن الممی زات الواطئ ة ومقاومتھ ا الجی دة للتآك ل وتوص یلھا الح راري الع الي وتتعرض سبائك . [2]وقابلیتھا الممتــازة للتشغیل وللصب وللحام األلمنیوم المستخدمة ف ي الص ناعات المختلف ة وخصوص ًا ص ناعة الطائرات إلى انخفاض مقاومتھا عند تعرضھا إلى ظ روف العم ل وتع د تقنی ة إض افة . ج ات الح رارة العالی ة وبتحمی ل ع اٍل وعن د در الم واد الس یرامیكیة إل ى الس بائك المعدنی ة ومنھ ا س بائك األلمنی وم مرغوب ة اقتص ادیًا إلنت اج الم واد المتراكب ة ذات األس اس واضـح في لما تضفي علـى المادة مـن تحسـن) mmcs(المعدني مت از العدی د ت. [3]عن د درج ات الح رارة العالی ة يالمیكانیك أدائھا م ن الم واد المتراكب ة وب األخص ذات األس اس المع دني والمق واة اص الت ي نال ت الكثی ر م ن ب المواد الس یرامیكیة ب الكثیر م ن الخ و لذلك كانت ھناك حاجة ماسة لفھم طبیعة التص رف لھ ذه , االھتمام .[4]المواد وتأثیرھا في خواص المادة المتراكبة تص نیع ھ ذه الم واد ھ ي غی اب أن أھم الصعوبات التي تواجھ لذلك یعد تحدی د طریق ة , التبلل بین السبائك المعدنیة وطور التقویة التص نیع م ن أھ م متطلب ات نج اح اس تخدام الم واد المتراكب ة ذات mailto:srmade@yahoo.com 2011)( 78 90 ، صفحة3، العدد 7مجلة الخوارزمي الھندسیة المجلد حسین إبراھیم دمد عماسر 79 األساس المعدني المق واة ب المواد الس یرامیكیة وذل ك لع دم مالءم ة الدراس ات طرائ ق الس باكة التقلیدی ة مم ا أدى إل ى قی ام الكثی ر م ن . حول أیجاد سبل جدیدة لتصنیع المواد المتراكبة وحتى یومن ا ھ ذا وتع د ك ل م ن طریق ة تقنی ة المس احیق والس باكة ب المزج م ن أھ م التقنی ات المتبع ة إلمكانی ة الحص ول عل ى توزی ع متج انس لل دقائق السیرامیكیة خالل األرضیة وبالت الي الحص ول عل ى االس تمراریة .[5]المطلوبة للخواص وفیما یأتي استعراض لعدد من البح وث الت ي اھتم ت ب المواد .المتراكبة وتطویرھا ت أثیر إض افة mustafa [6]درس الباح ث 1995فف ي ع ام حی ث , )al-22%si(ألیاف من االلومینا ف ي مع دل البل ى لس بیكة تم ت إض افة ألی اف االلومین ا إل ى الس بیكة باتب اع تقنی ة الس باكة إضافة ألیاف االلومینا إلى زیادة الحمل المطلوب ت دي اذبالضغط من حمل االنتق ال إل ى حم ل البل ى الش دید ألكث ر م ن ث الث م رات . مقارن ة م ع الس بیكة األس اس وتقل ل أیض ًا م ن معام ل االحتك اك ویبقى معدل البلى الذي یتم عنده االنتقال من البلى االوكسیدي إلى والس بیكة المض اف ألیھ ا ألی اف البلى الشدید ثابتًا للسبیكة األس اس .الذي یتم عنده االنتقال یكون مختلفًا تمامًاااللومینا إال أن الحمل ت أثیر المجانس ة 1998ع ام [11]كم ا درس ت الباحث ة أس راء الحراری ة ف ي مقاوم ة البل ى لس بیكة األلمنی وم الحاوی ة عل ى )16%si .( ود وأظھرت النتائج تحسنًا في مقاوم ة البل ى وذل ك یع ئق إلى تحول دقائق السلیكون من الشكل ذي الحافات الحادة إلى دقا فضًال عن أن معدل البلى یق ل بزی ادة , مستدیرة تقریبًا بعد المعاملة .سرعة االنزالق [7]وآخ رون smagorinskiوف ي نف س الع ام ق ام الباح ث بدراس ة الخ واص المیكانیكی ة لم ادة متراكب ة ذات أس اس م ن دعم ة بم زیج م ن الحبیب ات الس یرامیكیة ومحض رة األلمنی وم وم وق د تب ین أن , بتقنیت ي میتالورجی ا المس احیق وال رش بالبالزم ا الخ واص المیكانیكی ة والفیزیائی ة تك ون أفض ل للم ادة المتراكب ة ل المحضرة بتقنیة میتالورجیا المساحیق مثل معامل المرونة ومعام .التمدد الحراري 2000ع ام perez & yawny [8]كم ا وق ام الباحث ان بدراسة خاصیة متانة الكسر لنوعین من المواد المتراكب ة المعدنی ة م ـن م ادة ) %15(مق واة بنس بة ) al-si-mg(األول ى س بیكة , من كاربید ) %15(مقواة بنسبة ) al-si(والثانیة سبیكة , األلومینا الس لیكون وأجری ت عملی ة تلدی ـن للم ادتین عن د درج ة ح رارة )340˚c ( ومدة)24hr (وتوصال . وتم أجراء اختبار متانة الكسر إل ى أن أج راء المعامل ة الحراری ة تحس ن م ن قیم ة متان ة الكس ر وكذلك اإلجھاد المطلوب لنمو تقدم الشق یكون ذا قیمة عالیة ولیس . ھناك تأثیر لدرجة حرارة االختبار على قیم متانة الكسر م ادة متراكب ة [12] حض ر الباح ث ح ازم ) 2001(وف ي ع ام )al 4%cu -al2o3 mgo ( دق ائق ودرس ت أثیر اض افة وبالت الي ) al – cu(تبللی ة االلومین ا م ع الس بیكة ف ي المغنیس یا ھ رت النت ائج ان ظبع ض الخص ائص المیكانیكی ة وا ف يثیرھ ا أت -al2o3(افض ل نس بة مغنیس یا مض افة ال ى خل یط المس حوق mgo ( كان ت بنس بة)ب ان مقاوم ة الش د القص وى والح ظ %) 14 هبعد) %0.5wt(والصالدة تزداد مع زیادة نسبة االلومینا الى حد مغایرا ولكنھا تبقى عند قیم اعلى مما علی ھ ف ي تسلك المادة سلوكُا الس بیكة االس اس، بینم ا تق ل المطیلی ة باس تمرار م ع زی ادة نس بة الحبیبي وعالوة على ذلك وجد ان زیادة الحجم. االلومینا المضافة دي الى نقصان في مقاومة الشد القصوى والصالدة بینم ا ت زداد ؤی المطیلی ة م ع زی ادة الحج م الحبیب ي ولكنھ ا تبق ى اق ل م ن مطیلی ة .المادة االساس بانت اج م ادة متراكب ة [13]وفي العام ذاتة ق ام الباح ث ع دنان وبتقنی ة الس باكة ) al – 4.5 % cu – 1.5% mg( ذات اس اس حراریةشتیت دقائق االلومینا فیھا ومن ثم اجراء معاملة حیث تم ت ساعة، ثم اج ري ) 1(ولمدة ) 515c°(محلولیة عند درجة حرارة وبازمان مختلفة واس تنتج ان ) 190c°(التعتیق عند درجة حرارة اضافة االلومینا یؤدي الى زیادة الصالدة ونقصان معدالت البلى، ب ة للوص ول ال ى اقص ى ص الدة التعتی ق المطلو م دة كما الحظ ان زداد م ع زی ادة االلومین ا، وم ن خ الل فح ص البنی ة المجھری ة ت باستخدام المجھر االلكتروني الماسح تبین ان االلومین ا تت وزع ف ي كما الحظ من . سبیكة االساس بشكل متجانس على الحدود البلوریة ترس ب خالل فحص حیود االشعة السینیة نقص ان نس ب الط ور الم )cu al2 (مع زیادة نسب االلومینا. بتحضیر سبیكة [14]قامت الباحثة میرفت ) 2005(وفي عام )al-4%cu-1.5%mg ( وتقویتھ ا ب دقائق م ن م ادة الزركونی ا )zro2 ( مقاوم ة توبكس ر وزن ي وحج م حبیب ي مختلف ین ودرس الشد والمطیلیة والصالدة لتل ك الم ادة المتراكب ة وق د بین ت النت ائج كل من الصالدة ومقاومة الشد مع زیادة نسبة الزركونیا ازدیاد قیم ث م تس لك الم ادة س لوكا مغ ایرا ) % wt 3.5(المض افة ال ى ح د ولكنھا تبقى عند قیم اعلى مم ا ھ ي علی ة ف ي الس بیكة االس اس ف ي حین لوحظ ان قیم المطیلیة تقل باستمرار مع زیادة نسبة الزركونیا ي لدقائق الزركونیا على الخواص ثیر الحجم الحبیبأاما ت. المضافة قلیالًَ في ق یم مقاوم ة الش د اًَالمیكانیكیة فقد لوحظ ان ھناك انخفاض والصالدة مع زیادة الحجم الحبیب ي ل دقائق الزركونی ا بینم ا ھنال ك زیادة قلیلة في قیم المطیلیة مع زی ادة الحج م الحبیب ي ولكنھ ا تبق ى .اقل مما ھي علیھ في السبیكة االساس الھدف من البحث .٢ دراسة تص نیع م واد متراكب ة بطریق ة الس باكة ب المزج وذل ك -١ بإضافة نوعین مختلفة من الم واد السیرامیكیـ ـة وھ ـي دق ائق ) (alsi-mgالزركونی ا ودق ائق االلومین ا إل ـى سبیكــ ـة ). and 1 % 0.2, 0.4 0.8, 0.6 ,( وبنسـب مختلفـة میكیة الم ذكورة ف ي اع اله دراسة تأثیر اض افة الم واد الس یرا -٢ على الخواص المیكانیكیة للسبیكة االساس والمتمثلة بخواص .الشد والبلى والصالدة دراس ة أط وار التقوی ة الناتج ة بع د المعامل ة الحراری ة -٣ للسبیكة األساس والم ادة المتراكب ة ع ن ) االصالد بالترسیب( . طریق فحص حیود األشعة السینیة ی ة لك ل م ن م ادة االس اس والم ادة البنی ة المجھر دراس ة -٤ .المتراكبة المنتجھ بأستخدام المجھر البصري الجزء النظري .٣ والصناعي بشكل كبیر على التقدم ) التكنولوجي(یعتمد التطور في إنت اج الم واد الھندس یة ونتیج ة ل ذلك ظھ رت الحاج ة لتع ویض زمنیة المواد الھندسیة التقلیدیة التي استخدمت في الصناعة فترات طویل ة بم واد بدیل ة تحم ل ص فات ھندس یة عالی ة تتف وق بھ ا عل ى كص ناعة ,المواد التقلیدیة وذلك الستغاللھا في مختلف الص ناعات الس یارات والط ائرات والس فن والص ناعات الكھربائی ة والمع دات .[2]الریاضیة كالمعادن (ومن خالل دراسة خواص المواد الھندسیة المختلفة لوحظ وج ود تب این ف ي خ واص تل ك الم واد ) واللدائنوالسیرامیك م ن حی ث المقاوم ة والمتان ة واللدون ة وتحم ل درج ات الح رارة ونتیج ة لم ا تق دم ظھ رت . [3]والموص لیة الكھربائی ة وغیرھ ا الحاجة إلى إنتاج م واد تجم ع الص فات الھندس یة المش تركة للم واد تمت از بھ ا الس بائك الھندسیة مثل المقاومة والمتانة والصالدة الت ي 2011)( 78 90 ، صفحة3، العدد 7مجلة الخوارزمي الھندسیة المجلد حسین إبراھیم دمد عماسر 80 وخف ة ال وزن والمقاوم ة الكیمیائی ة الت ي تمت از بھ ا الل دائن وك ذلك . تحمل درجات الحرارة العالیة التي تمتاز بھ ا الم واد الس یرامیكیة composite(ل ذلك ت م االتج اه إل ى إنت اج الم واد المتراكب ة materials ( التي تعرف بأنھا المواد الناتج ة م ن دم ج م ادتین أو كثر مختلفتین إلعطاء مزیج من الخ واص المیكانیكی ة والفیزیائی ة أ أي أنھ ا . والكیمیائیة ال یمكن الحص ول علیھ ا م ن الم واد األص لیة م ن تحمل الصفات المرغوبة في المواد المكونة لھا وتلغي أو تحد .[4]تأثیر الخواص غیر المرغوبة الجزء العملي .٤ راس ة إل ى الم ادة األس اس تقسم المواد المس تخدمة ف ي ھ ذه الد ومواد التقویة حیث إن مادة األساس المستخدمة في ھذا البحث ھي لم ا تتمی ـز ب ھ م ن خ واص وتطبیق ات عل ى ) (al-si-mgسبیكـة وت م اس تخدام ن وعین م ن الم واد السیـرامیكی ـة , نط اق واس ـع وإضافتـھا إلیھا بنس ـب مختلف ـة ودراس ـة تأثیرھ ـا عل ى الخ واص نظـرا لما تتمیـز بـھ ھذه الدقائـق من خواص میكانیكیـة المذكـورة وقد تم إجراء عملیة تجفیف للمساحیق قبل االستخدام إلزالة . عالیة ) (c˚500الرطوبـة الموجـودة عل ى س طحھا عن د درج ة ح رارة : لتحسین قابلیة الترطیب عند إضافتھا للسبیكة األساس وھما a دقائق االلومینا)al2o3( :ـم استخدام مسحـوق ناع ـم حیـث ت مـن دقائق االلومینا المختب ـري وبحج ـم دق ائق یت راوح ب ین 0.1μm) 20μm > particle size≥ .( b دقائق الزركونیا)zro2( : حیث تم استخـدام مسح ـوق ناع ـم م ن دق ائق الزركونی ا المختب ـري وبحج م دق ائق یت راوح ). ≤0.1μm) 20μm > particle sizeبین ) (al-7%si-0.3%mgیـ ـر السبیكـ ـة األسـ ـاس ت م تحض وبكتل ة معلوم ة داخ ل ) (al-12%siوذلـ ـك بصھـ ـر سبیكــــ ـة بودق ة م ن كاربی د الس لیكون وباس تعمال ف رن كھرب ائي ذو فوھ ة ) (c˚750حیث اجریـت عملی ة الص ھر عن د درج ة ح رارة . علیـا لت ام وبعد التأكد م ن ح دوث الص ھر ا , لضمان إتمام عملیة الصھر إلى السبیكة لغ رض تقلی ل ) (%99.99یتم إضافـة األلمنیوم النقي نس بة الس لیكون إل ى النس بة المطلوب ة م ع التحری ك المس تمر ث م إض افة المغنیس یوم إل ى داخ ل المنص ھر بع د أن ت م . للمنص ھر تھیئتـھ بشكل حبیبات صغیـرة وبنقاوة عالی ة ج دًا وتغلیف ھ برق ائق ع اتصالھا مع الھ واء تفادی ًا لح دوث عملی ة من األلمنیوم بشكل یمن األكس ـدة وتغم ر داخ ل المنص ھر م ع تثبی ت الف رن للحف اظ عل ى ث م , سیولة المنصھر لحین اكتمال ذوبانیة المغنیسیوم مع المنصھر م ع , تت ـم مجانس ـة المنص ھر بواسط ـة قض یب م ن الكراف ـیت كلوری د ث م إض افة . التحریـك المستمر للمنصھ ـر لحی ـن التجان ـس بشكل مسحـوق إلى المنصھر حیث یعمل عل ى ) (alcl4األلمنیوم طرد الغازات وإزالة الخبث نتیجـة لتفاعلـھ مع المنصھر وتكوی ـن , طبقة الخبث التي تعلو سطح المنصھ ـر والت ي ت زال م ن الس طح بعدھا تتم عملیة صب منصھر السبیكـة في قالب اسطواني الشكـل م ع مالحظ ـة ) (130mmوارتف اع ) (15mmم ن الف والذ بقط ر لمنع ح دوث ) (c˚250التسخین المسبـق للقالب إلى درجة حرارة وبعد تجمد المنصھر بش كل ت ام تخ رج . التبرید المفاجئ للمنصھر وأجری ت , الص بة م ن القال ب للحص ول عل ى السبیك ـة األس اس مبین عملیة التحلیـل الكیمیائـي للسبیكة األساس وكانت النتیجة كما .1)(في الجدول تحضیـــر المـادة المتراكبـــة بـطریقـــة السباكــة ب المزج وتم stirring casting) ( وباس تعمال تقنی ة الدوام ةvortex technique) ( وعلیــھ ت م تقطی ـع السبیكـ ـة األس اس إل ـى قطـ ـع صغیـرة لغـرض تحدیــد الـوزن المطـلــوب منھـ ـا استنـ ـادا إل ـى ر الوزنــي لمادة التقویــة لكــل مـن دقائق الزركونیا ودق ائق الكسـ ). (and 1% 0.8, 0.6, 0.4, 0.2االلومینا وللنســب المطلوبـ ـة ثم تم وض ع القط ع الموزون ة داخ ل البودق ـة وادخل ـت إل ى الف رن لضم ـان ) (c˚750الكھربائـي الذي تم تثبیت ـھ عن د درج ة ح رارة ولتجان ـس توزی ـع دقائ ـق الم ـواد . كام ـل انصھار السبیكـة بشكـل السیرامیكی ـة المضاف ـة داخ ـل المنصھ ـر اس تعمل لھ ـذا ال ـغرض خالط كھربائـي مصـنوع من الفوالذ ومزود بمروحی ـة م ـن م ـادة ث ـم انـ ـزل الخ الط الكھرب ائي إل ى داخ ل البودق ة , مقاوم ة للص ـدأ ریة للحف اظ عل ى الموجودة داخل الفـرن المثبت عند الدرجة الحرا ) (r.p.m 900وت م ت دویر المنص ھر بس رعة , س یولة المنص ھر وبع ـد ذل ك ت م إض افة ال دقائق , للحص ول عل ى دوام ة داخل ـھ السیرامیكیة التي تم تغلیفھا برقائق من األلمنیوم والمسخنـة مسبق ـًا إلزال ـة الرطوب ـة وتحسی ـن تشتی ـت ) (c˚500إلى درج ة ح رارة ونتیج ـة لفعـ ـل الدوام ـة یت ـم سح ـب . منصھ ـرالدقائ ـق داخ ـل ال مسح ـوق الدقائ ـق السیرامیكی ـة إلـ ـى داخ ـل المنصھ ـر المعدن ـي وتوزیعـھ خاللـھ وبعـدھـا یتــم تحریـك المنصھر لمـدة تتراوح بین 1-5min) ( لحیـن تجانـس المنصھـر ال ـذي یك ـون بشك ـل عال ـق . لف والذ ال ـذي ت ـم تس خینھ بعدھا تتـم عملیـة الصب في قال ب م ـن ا لمن ـع ح ـدوث التبری ـد ) (c˚250مسبقـ ـًا إلـ ـى درج ـة ح ـرارة لیتجم د للحص ول عل ى الم ادة ث م یت رك . المفاج ـئ للمنص ھر وتعاد العملی ـة لع ـدة م رات وحس ب النس ـب المطل وب , المتراكبة إضافتھـا إلـى السبیكـة األساس لك ل م ن دق ائق الزركونی ا ودق ائق .ومینااالل -١ جدول .یوضح التركیب الكیمیائي للسبیكة األساس بعد الصب (%)المئویة النسبة العنصر si 7.2 fe 0.41 cu 0.15 mn 0.15 mg 0.35 zn 0.015 ti 0.019 cr 0.01 ni 0.005 pb 0.02 sn 0.007 sb 0.023 al rem. للس بیكة األس اس بعدھا ت م إج راء عملی ة االص الد بالترس یب :والمادة المتراكبة و كما یلي a ت ـم إج راء ھ ذه المعامل ـة بدرج ة ح رارة : المعاملة المحلولی ة 520˚c) ( لك ـل م ـن السبیك ـة األس اس والم ـادة المتراكب ـة ).(1hrولمـدة bبع ـد انتھ اء زم ـن المعامل ـة ت م التبری د بالم اء إل ى : اإلخم اد .درجـة حرارة الغرفـة 2011)( 78 90 ، صفحة3، العدد 7مجلة الخوارزمي الھندسیة المجلد حسین إبراھیم دمد عماسر 81 cاجریت ھ ذه العملی ـة للسبیك ـة األس اس : الصطناعيالتعتیق ا وبأزم ان مختلف ة ) (c˚170والمادة المتراكبة بدرج ة ح رارة .ثم التبرید بواسطة الھواء) (hr 12-2ھي تم إجراء فحـص الشد للعینـات القیاسیـة بعد عملیـة التشغی ـل ث م ) (1mm/minوبسرعـة )2.5ton( باستخدام جھاز الشد وبسعة ق یم مقاوم ة الش ـد ومقاوم ـة الخض وع و المطیلی ـة لك ل م ن إیجاد .المـادة األسـاس و المادة المتراكبة وت م إج راء اختب ار البل ى باستخ ـدام جھ از البل ى االلتصاق ـي وبتس لیط الحم ل بص ورة عمودی ـة عل ـى ) (pin-on diskن وع لمادة األساس والمادةل) (and 10 n 7 , 5 , 2العینـة وبأحمـال وت م وزن العین ة قب ل . دقیق ة ) (30المتراكبة لفت رة زمنی ة مق دارھا ومن , )(w1-w2وبعد إجراء االختبار وحساب الفرق في الوزن .ثم حساب معدل البلى حیث ))فیكرز (( تم إجراء فحـص الصـالدة الدقیقة بطریقـة . على سطح العینة) (5sec لمدة) (kg 1تم تسلیـط حمـل مقداره فح ص حی ود األش عة و فح ص البنی ة المجھری ة، تم إج راء ومن ثم السینیة لغرض معرفة األطوار الناتجة في السبیكة األساس والمادة لحس اب المس افة ب ین ))ب راك((وق د ت م أتب اع ق انون , المتراكب ة الذری ة وتحدی د األط وار المتكون ة والمب ین ف ي العالق ة المستویات :االتیة 2d sinθ = nλ ... (1) :حیث أن )θ ( زاوی ة الحی ود ,)n ( 1=مرتب ة الحی ود ،)d ( المس افة ب ین .الطول الموجي لالشعة السینیة) λ(المستویات، النتائج والمناقشة .٥ وال ذي یوض ح تأثی ـر زم ن ) (1م ن خ الل مالحظ ة الشك ـل س اس یالح ظ إن ص الدة التعتی ـق ف ي ق یم الص الدة للسبیك ـة األ السبیكـة األساس تزداد مع زیادة مدة التعتیق لتصل إلى أعلى قیمة ویعود س بب ذل ك إل ى ترس یب ) (8hrلھا عند مدة تعتیـق مقدارھا بعدة مراح ل حی ـث تتك ـون ) (mg2siدقائـق صغیـرة مـن الطور في المراحـل األولى من التعتیـق وھي تزید ) (gp.zoneمناطـق وھ و المرك ـب غی ر ) β`(ث م یتك ون الط ور , م ـة الص الدة م ن قی وال ـذي ی رتبط بالط ـور األس اس وال ذي یزی د ) (mg2alالمس تقر وھ ـو الط ـور ) β(ث م یتك ـون الط ور , أكث ر م ن قیم ة الص الدة الصلـد والذي یكسب السبیكـة خواص مقاومة ) (mg2siالمستقـر ئج فحص حیود األشعة وھذا ما اكدتھ نتا. [9]عالیة وصالدة عالیة السینیة للسبیكة األساس قبل وبع د المعامل ة الحراری ة والمبین ة ف ي حی ث تعم ل ھ ذه ال دقائق إل ى إعاق ة حرك ة ). (3,2نلیالج دو . االنخالع ات مم ا ی ؤدي إل ى تص لید السبیك ـة وزی ادة مقاومتھ ا یالحظ انخفاض ق یم ) (8hrوباستمرار زیادة التعتیق إلى أكثر من یعود سبب ھذا االنخف اض إل ى تجم ع ال دقائق المترس بة الصالدة و وتكون جسیمات اكبر حجمًا فضًال عن فقدان انفعاالت التطابق بین باإلضافـ ـة إلـ ـى تكویـ ـن . والط ور األس اس) (mg2siالط ور أطوار وسطیة ناتجـة عن العملیات االنتشاریة لعناصر السبك قب ل ن خ الل حی ود االش عة وبع د المعامل ة الحراری ة حی ث الحظن ا م إن ظھ ور ھ ذا الط ور ). (alfesiالسینیة ظھور الط ور الث انوي ) (mg2siی ؤدي إل ى س حب الس یلیكون وت أخیر ترسی ـب الط ور وبالتالـي تكویـن عوائـق اقـل لحركـة االنخالعات مما یـؤدي إلـى . انخفاض قیـم الصالدة .زمن التعتیق االصطناعي على قیم الصالدة للسبیكة األساس یوضح تأثیر -١ شكل 0 50 100 150 200 250 0 2 4 6 8 10 12 14 aging time (hr) vi ck er a h ar dn es s (k g\ m m 2) matrix (al-7%si) 2011)( 78 90 ، صفحة3، العدد 7مجلة الخوارزمي الھندسیة المجلد حسین إبراھیم دمد عماسر 82 -٢ جدول .صبنتائج فحص حیود األشعة السینیة للسبیكة األساس بعد ال i/io phase ds(a)˚ dm(a)˚ 2θ 100 si 3.138 3.165 28.1 100 al 2.338 2.358 38.1 47 al 2.024 2.046 44.2 60 alfesi 1.920 1.940 46.7 35 si 1.638 1.652 55.5 35 alfesi 1.431 1.441 64.5 24 al 1.221 1.224 77.9 7 al 1.169 1.169 82.3 -٣ جدول نتائج فحص حیود األشعة السینیة للسبیكة األساس بعد المعاملة مدة ) c˚170(والتعتیق االصطناعي عند درجة حرارة المحلولیة )8hr.( i/io phase ds(a)˚ dm(a)˚ 2θ 40 mg2si 3.700 3.701 28.2 100 mg2al 2.510 2.514 35.2 100 al 2.338 2.361 38.0 47 al 2.024 2.044 44.2 15 alfesi 1.929 1.934 46.9 20 mg2si 1.599 1.649 55.6 35 alfesi 1.429 1.439 64.6 60 mg2si 1.320 1.320 69.9 70 mg2al 1.224 1.223 77.9 7 al 1.169 1.170 82.2 17 si 1.108 1.106 88.2 .یوضح تأثیر النسب الوزنیة للدقائق المضافة للسبیكة األساس على قیم الصالدة -٢ شكل یبین تأثیر النسب الوزنیة للدقائق المض افة ف ي ق یم ) (2الشكل , من السبائ ـك الصالدة للسبیكة األساس بعد الصب ولمجموعتیـن ب دقائق االلومین ا وبحج م حبیب ي ب ین ) (aالمجموع ة األول ى ≥0.1μm) 20μm>p.s ( والمـجمـوع ـة الثــانی ـةb) ( ب دقائق ) (20μm>p.s≥0.1μmالزركونی ا وبـحـج ـم حبیب ـي بیـ ـن ح ـظ حیـث یـال). (and 1% 0.8, 0.6, 0.4, 0.2وبنسـب وزنیھ إن قیـم الصالدة للسبیكـة األساس تزداد مع زیادة النس ب الوزنی ـة للدقائـق المضافـة ولك ال المجم وعتین لتص ل إل ى أعل ى قیم ـة لھ ا م ع مالحظ ـة إن الزی ادة الحاصل ـة ف ي قی ـم ) (%1عن د النسب ـة اكبر مقارنة مع المجموعة الثانیة a)(الصالدة للمجموعـة األولى )b (ذلك إلى الصالدة العالیة لدقائق االلومینا مقارنـة ویعود سبب .مع دقائق الزركونیا إن سبب الزیـادة الحاصلـة فـي قیـم صـالدة السبیكـة األساس یعود إلى طبیعة ھذه الدقائق حیث تعمل الدقائق التي یزی د حجمھ ا كعوائق لتشوه السبیكـة األساس وذلك بسبب صالدتھا ) (1μmعن ) (1μmا وتعم ل الدقائ ـق والت ـي یق ـل حجمھ ـا ع ن كم , العالی ـة والمشتتـ ـة داخ ـل السبیكـ ـة علـ ـى إعاقـ ـة حركـ ـة االنخالعـ ـات المتكونــة وبالتالــي سـوف یساھـم كـال النوعیــن فــي زیادة قیم ة الصالدة باإلضافة إلى اختالف الحجـم الحبیبـي للدقائـق المضافـة ر بعـض العوامـل ومـن ضمنھـا المسافــة سـوف تــؤدي إلــى تغیــ : [10] تبعًا للعالقة اآلتیة )(dp بیـن الدقائــق 0 50 100 150 200 250 300 0 0.2 0.4 0.6 0.8 1 1.2 weight fraction (%) v ic ke rs h ar dn es s (k g\ m m 2) (al2o3) (zro2) 2011)( 78 90 ، صفحة3، العدد 7مجلة الخوارزمي الھندسیة المجلد حسین إبراھیم دمد عماسر 83 dp= 2d2/3vp(1-vp)………………...……… ….(2) :حیث إن ) d ( حجم الدقائقm)μ( ,vp) (الكسر الحجمي للدقائـق, dp) (المسافـة بیـن الدقائـق. سیرامیكیة في ھكذا شروط سوف تعمل إن وجود ھذه الدقائق ال زنیة العالیة على إعاقة حركة االنخالعـة بنسبة اكبر عند النسب الو ولك ي تم ر االنخالع ـة خ الل ھ ذه الدقائـ ـق , من الدقائق المض افة المشتتة فأن اإلجھاد یجب أن یكون كافیًا للحنـي وبالتالـي فأن ذلك .ني زیادة قیم الصالدةسوف یتطـلب زیادة الحمل المسلـط وھذا یع بعد إجراء عملیة التعتیق االصطناعي للسبیكـة األساس المقواة ولك ال المجموعتی ـن وج د إن إض افة دقائ ـق ك ل م ن الزركونی ا وااللومینا إلى السبیكـة األساس الیؤثر في مراحل التعتیق حیث إن ھا قیم الصالدة تزداد مع زیادة مدة التعتیق لتصل إلى أعلى قیمة ل وان صالدة السبیكة المق واة ت زداد ). (8hrعند مدة تعتیق مقدارھا عن ما ھو علیھ في السبیكة األس اس وان مع دل الزی ادة ی زداد م ع زیادة الكسر الوزني لل دقائق المض افة والس بب یع ود إل ى اش تراك أكثر من آلیة في حدوث التقویـة والمتمثلـة أوال باالصالد بالتشتیت إضافة الدقائـق السیرامیكیـة والموزعـة داخـل أرضیة الناتـج مـن السبیك ـة األس اس حی ـث تعم ل كعوائ ـق لتش وه السبیك ـة وإعاق ة حرك ـة االنخالعـ ـات وثانی ـًا االص ـالد بالتـرسی ـب المتمثلـ ـة و الص الدة العالی ة وال ذي ذ) (mg2siبظھ ـور الط ور المس تقر الع ات مم ا ی ؤدي إل ى األخر عل ـى إعاق ة حرك ـة االنخ یعمل ھـو زی ادة ق یم الص الدة للم ادة المتراكب ة باإلض افة إل ى ت أثیر الحج ـم حی ث نالح ظ إن ) (1μmالحبیبـي للدقائـق المضافـة التي اقل م ن قیـم الصالدة تزداد مع نقصان الحجـم الحبیبـي ویمكـن تفسیر ذلـك : [10] علـى أساس العالقة التالیة ti=3gm.b`.vp/2d2(1-vp) …(3) :حیث أن )ti (اإلجھاد المطلوب لمرور االنخالعة,b`) (بیرجر، متجھ vp) (الكسر الحجمي، gm)( معامل القص للمادة األساس, )d ( حجم الدقائقm)μ.( ویمك ـن مالحظ ـة العالق ـة العكسی ـة بی ـن اإلجھ اد المطل ـوب ومرب ع الحج ـم الحبیب ـي لھ ـذه لمرور االنخالع ـة خ ـالل الدقائ ـق وھـذا یعن ـي إن أي نقص ـان ف ـي قیم ـة الحج ـم الحبیب ي , الدقائـق سیكـون مصحوبـًا بزیـادة ملحوظـة ف ـي قیم ـة اإلجھ اد المطل ـوب . لمرور االنـخالعـة وبالتالـي زیادة فـي قیمـة الصـالدة والمقـاومـة عـظم ـى بع ـد عمـلی ـة یبی ـن تغی ـر قیـ ـم الص ـالدة ال) (3والشك ـل م ع الكس ـر ) (8hrولمـدة ) (c˚170التعـتیـق عنـد درجـة حرارة الوزني للدقائق المضافة لدقائق االلومین ا ودق ائق الزركونی ا حی ث یالح ظ أن ق یم الص الدة العظم ى ت زداد م ع زی ادة نس بة ال دقائق المض افة م ع مالحظ ـة أن الزی ادة الحاصل ـة ف ي قی ـم الص الدة ع ـة األول ى اكب ر مقارن ـة م ع المجموع ـة الثانی ـة ویع ود للمجمو سبـب ذلـك إل ـى الص الدة العالی ـة لدقـائ ـق االلومین ا مقارن ـة م ـع .دقائق الزركونیا من خالل فحص الشد للسبیكة األساس والمادة المتراكبة وبع د المعامل ة الحراری ة الم ذكورة ف ي اع اله ت م حس اب مقاوم ـة الش د د الخضوع والمطیلیـة لكـل مـن السبیكــة األس اس القصوى وإجھا مدعم ـة بدقائ ـق م ن االلومین ا ) (aوالمـجمـوع ـة األول ى . مــدعمـة بـدقـائـق مـن الزركونیا) (bوالمـجمـوعـة الثــانیـة ).(8hrلمدة ) (c˚170بعد التعتیق االصطناعي عند درجة حرارة ئق المضافةیوضح العالقة بین قیم الصالدة العظمى والنسب الوزنیة للدقا -٣ شكل 0 50 100 150 200 250 300 350 0 0.2 0.4 0.6 0.8 1 1.2 weight fraction (%) vi ck er s h ar dn es s (k g\ m m 2) (al2o3) (zro2) 2011)( 78 90 ، صفحة3، العدد 7مجلة الخوارزمي الھندسیة المجلد حسین إبراھیم دمد عماسر 84 یبی ـن تغی ـر قی ـم مقاوم ـة الش ـد القص ـوى ) (6,5,4األش كال وإجھ اد الخض وع والمطیلی ة عل ى الت والي للسبیك ـة األس اس . والسبیك ـة المق واة م ـع النس ـب المضاف ـة ولك ـال المجمـوعتی ـن زی ادة مقاوم ة الش ـد القص وى وإجھ اد 5,4)(نالح ظ م ن الش كلین الخضوع مع زیادة النسب الوزنیـة للدقائ ـق المضاف ـة لتص ل إل ى ولك ال المجموعتی ـن ) (%0.6أعلى قیمـة لھ ا عن د النس بة الوزنی ة وبعد ذلـك تسلـك المادة سلوكًا مغایرًا حیث تنخفض ھذه القیم م ـع كـن تبقـى محافظة على زیادة النسب الوزنیـة للدقائـق المضافـة ول إن الزیادة الحاصلة في . قیم أعلى مما ھو علیھ في السبیكة األساس ھذه القیم للسبیكـة المق واة یع ود إل ى طبیع ـة ھ ذه الدقائ ـق الص لدة والموزعـة فـي السبیكـة األس اس وبأحج ام حبیبی ـة مختلف ـة والت ي بب زی ادة تعم ل عل ى زی ادة مقاوم ة الس بیكة وكم ا بین ا آنف ًا ف ي س الص لد ) (mg2siالص الدة باإلض افة إل ى ترس یب دق ائق الط ور .الذي یكسب السبیكة خواص مقاومة جیدة ).(8hrلمدة ) (c˚170بعد التعتیق االصطناعي عند درجة حرارة یوضح العالقة بین قیم الشد القصوى والنسب الوزنیة للدقائق المضافة -٤ شكل ).(8hrلمدة ) (c˚170بعد التعتیق االصطناعي عند درجة حرارة یوضح العالقة بین قیم إجھاد الخضوع والنسب الوزنیة للدقائق المضافة -٥ شكل 0 50 100 150 200 250 300 0 0.2 0.4 0.6 0.8 1 1.2 weight fraction (%) te ns ile s tr en gt h (m pa ) (al2o3) (zro2) 0 50 100 150 200 250 300 0 0.2 0.4 0.6 0.8 1 1.2 weight fraction (%) y ie ld s tr en gt h (m pa ) (al2o3) (zro2) 2011)( 78 90 ، صفحة3، العدد 7مجلة الخوارزمي الھندسیة المجلد حسین إبراھیم دمد عماسر 85 ).(8hrلمدة ) (c˚170االصطناعي عند درجة حرارة بعد التعتیق یوضح تغیر قیم المطیلیة مع النسب الوزنیة للدقائق المضافة -٦ شكل كمـا إن مقاومـة الخض وع للسبائ ـك المق واة تتناس ـب عكسی ـًا مـع الجذر التربیعــي للمسافـ ـة ب ین الدقائ ـق وعلی ـھ س وف ی ؤدي ذلك إلى زیادة مقاومة الخضوع للسبیكـة مع زی ادة نسب ـة الدقائ ـق موضح من خالل العالقة اآلتیة وكما) (%0.6المضافـة والى حـد [9] : yσ dp 1 α …(4) :حیث إن y)σ ( إجھاد الخضوع للمادة ,dp) (المسافة بین الدقائق. أما السلـوك المغایـر للمـادة المتراكبـة بعـد ھـذه النسبـة فـأن ـھ ـوب السباكــة والمسامیـة التـي یحصـل لھ ـا بع ـد قـد یعـود إلى عی الزی ادة عن ـد النس ـب العالیـ ـة م ن ال دقائق المض افة بس بب زی ادة لزوج ة المنص ھر باإلض افة إل ى حص ول تفاعـ ـل بی ـن األلمنی وم وعناصر السبـك داخل الس بیكة االس اس وتكوی ـن أط وار وسطی ـة األط وار عل ـى الھ ـش حی ـث تتجم ـع ھ ذه alfesi)( ومنھ ـا الحدود البلوریـة ممـا یـؤدي إلى ضعف الحدود البلوریة وانخفاض .مقاومة الشد والخضوع والمطیلیة للمادة المتراكبة أن السبیكة األس اس أب دت نقص انًا ف ي 6)(یالحـظ مـن الشكل وان النقص ان ف ي ق یم , قی ـم المطیلی ة عن د إض افة ھ ذه ال دقائق . دة النسـب الوزنیـ ـة للدقـائـ ـق المضافـ ـة المطیلیة یـزداد مـع زیـا حی ث إن المطیلی ـة تسل ـك سلوك ـًا معاكس ـًا للخ واص المتمثل ـة إن س بب ذل ك یع زى إل ى طبیع ة ال دقائق . بمقاومة الشد والصالدة السیرامیكیة الھشة والتي تعم ل عل ى تقلی ل المساف ـة بی ـن الدقائ ـق إل ى وج ود األط وار والت ي ت ؤدي إل ى تقلی ل المطیلی ة باإلض افة الھ ش والت ي تترس ب عل ى ) (alfesiالوس طیة ومنھ ا الط ور والجدولین . مما یؤدي إلى ضعفھا وتقلیل المطیلیة الحدود البلوریة یوضحان نتائج فحص حیود االشعة السینیة للمادة المتراكبة ) 5,4( .المقواة بكل من دقائق االلومینا ودقائق الزركونیا -٤ جدول حص حیود األشعة السینیة للمادة المتراكبة المقواة بدقائق نتائج ف مدة ) c˚170(بعد التعتیق االصطناعي عند درجة حرارة االلومینا )8hr.( i/io phase ds(a)˚ dm(a)˚ 2θ 100 mg2al 2.510 2.514 34.7 47 al 2.024 2.045 44.2 15 alfesi 1.929 1.939 46.7 35 alfesi 1.429 1.439 64.6 60 mg2si 1.320 1.357 69.1 10 al2o3 1.21 1.223 77.7 70 mg2al 1.224 1.223 77.9 -٥ جدول نت ائج فح ص حی ود األش عة الس ینیة للم ادة المتراكب ة المق واة ب دقائق م دة ) c˚170(بع د التعتی ق االص طناعي عن د درج ة ح رارة الزركونی ا )8hr.( i/io phase ds(a)˚ dm(a)˚ 2θ 40 mg2si 3.700 3.590 25.6 100 si 3.138 3.169 28.1 100 mg2al 2.510 2.517 35.1 35 alfesi 1.429 1.439 64.6 10 zro2 1.26 1.22 77.5 70 mg2al 1.224 1.223 77.9 7 al 1.169 1.169 82.3 یوضحان العالقة بین مع دل البل ى والحم ل ) (8و) (7الشكلین ة األس اس والم ادة المتراكب ة الحاوی ة المسلط عل ى ك ل م ن الس بیك 0 0.4 0.8 1.2 1.6 0 0.2 0.4 0.6 0.8 1 1.2 weight fraction (%) el on ga tio n (% ) (al2o3) (zro2) 2011)( 78 90 ، صفحة3، العدد 7مجلة الخوارزمي الھندسیة المجلد حسین إبراھیم دمد عماسر 86 على كل م ن دق ائق الزركونی ا ودق ائق االلومین ا وللنس ب المختلف ة ) (8hrولم دة ) (c˚170بع د المعامل ة المحلولی ة والتعتی ق عن د ویالحظ من خالل الشكلین إن معدل البلى للس بیكة األس اس . ًاایض البل ـى لھ ذه یزداد مع زیادة الحمل المس لط ویمك ـن تقسی ـم سل ـوك ) (mild wearالسبیك ـة إل ى ثالث ة أقس ام وھ ي البل ى الط ري حی ـث یك ـون حط ام البل ـى ) (n 5-2ویحدث ما بین ق یم األحم ال المتكون عبارة عن جسیمات ناعمة إذ یتكون غشاء اوكسیدي واقي الجھاز قرصحـة التالمـس بیـن العینــــة ویؤدي إلى انخفاض مسا والبلـــــ ـى االنتق الي . ع ـدل بلــ ـى قلی ل مم ـا ی ؤدي إل ـى م transition wear) ( ویحـــدث فــي منطقـــة األحمــال ما بیـن 5-7 n) .( والبلــى الشدیــدsever wear) ( ال ذي یح دث عن دما حی ث تك ون جس یمات ) (n 10-7تزداد قیم األحمال المسلطة ب ین ید المتكون ة حط ام البل ى كبی رة ومعدنی ة إذ تتكس ر طبق ة االوكس ث م , بمس احة كبی رة ب ین نت وءات الس طحین فیؤدي ذلك إلى اتصال .تتكسر تلـك النتوءات وتنفصل عن السطح ناعي عند یوضح العالقة بین معدل البلى والحمل المسلط للسبیكة األساس وتأثیر إضافة نسب من دقائق الزركونیا إلیھا بعد التعتیق االصط -٧ -شكل ).8hr( لمدة) (c˚170 درجة حرارة یوضح العالقة بین معدل البلى والحمل المسلط للسبیكة األساس وتأثیر إضافة نسب من دقائق االلومینا إلیھا بعد التعتیق االصطناعي عند -٨ -شكل ).8hr( لمدة) (c˚170 درجة حرارة 0 5 10 15 20 0 2 4 6 8 10 12 applied load (n) w ea r r at e (g m \c m ) (1%zro2) (0.6%zro2) (1%zro2) matrix (al-7%si 0 5 10 15 20 0 2 4 6 8 10 12 applied load (n) w ea r r at e( gm \c m ) (1%al2o3) (0.6%al2o3) (1%al2o3) matrix (al-7%si) 2011)( 78 90 ، صفحة3، العدد 7مجلة الخوارزمي الھندسیة المجلد حسین إبراھیم دمد عماسر 87 للس بیكة األس اس ی ؤدي إل ى إن إض افة دق ائق الزركونی ا نقصان معدل البلى وان النقصان یزداد مع زیادة النس ب المض افة ویعود سبب ذلك إلى صالدة ال دقائق المض افة نتیج ة , من الدقائق إلى ارتباط مقاومة البلى مع الص الدة الس طحیة وأص بحت منطق ة البل ى االنتق الي أكث ر وض وحًا بع د إض افة ھ ذه ال دقائق والت ي وم ن ) (n 7-5حصرت بالم دى م ن الحم ل المس لط الواق ع ب ین ان جھة أخ رى ل م یت أثر حم ل االنتق ال كثی رًا بنس بة دق ائق الزركونی ا ن بل ى األكس دة المضافة حیث یوضح الشكل ح دوث انتق ال ح اد م بینما انخفض معدل البلى للمادة المتراكب ة عن د , إلى البلى المعدني وأص بح ھ ذا ) (n 10-7 األحم ال المس لطة المحص ورة ب ین .االنخفاض اكبر بزیادة نسبة الدقائق المضافة إلى السبیكة األساس أما تأثیر إضافة دقائق االلومینا للس بیكة األس اس عل ى مع دل البلى مع زیادة الحمل المسلط فیالحظ أن إض افة ھ ذه ال دقائق إل ى الس بیكة ی ؤدي إل ى نقص ان مع دل البل ى وان النقص ان ی زداد م ع ادة النسب المضافة من الدقائق بسبب الصالدة العالیة ج دًا لھ ذه زی حی ث إن . الدقائق باإلضافة إل ى امتالكھ ا خ واص بل ى عالی ة ج داً إضافة ھذه الدقائق أثرت بشكل كبیر على حمل االنتق ال م ن البل ى االوكس یدي إل ى البل ى المع دني ال ذي انخف ض بش كل كبی ر وال ذي لسبیكـة األسـاس ومـع المادة المتراكبـة أصبح اقل حده مقارنة مع ا المقـواة ب دقائق الزركونی ا باإلضاف ـة إل ـى انخف اض مع ـدل البل ـى ). (n 10-7للم ادة المتراكب ـة عن د األحم ال العالی ـة م ا بی ـن ویستمـر االنخفاض بصورة كبیـرة بزیادة نسبـة الدقائـق المضافـة ى تحم ـل األحم ال العالی ة وذلك لطبیعـة ھذه الدقائـق وقدرتھـا علـ للثق ل كأنھ ا عناص ر حامل ة داخل س بیكة االس اس تتصرف حیث وتؤدي إلى عدم تالمس ) (load bearing element واإلجھاد .مباشر بین سطح العینة والقرص البنی ة المجھری ة للس بیكة االس اس قب ل ) 9(ویوض ح الش كل االلمنی وم المعامل ة الحراری ة حی ث نج د ان البنی ة عب ارة ع ن والس لیكون حی ث یالح ظ ان الش كل عب ارة ع ن الیوتكتی ك بش كل حبیبات دقیقة مع ظھ ور بل ورات الس لیكون بش كل ش جیري فض ُال والش وائب الموج ودة كالس لیكونع ن عناص ر الس بك االخ رى كالحدید والمنتشرة في اماكن مختلف ة داخ ل البنی ة المجھری ة حی ث تك وین اط وار وس طیة ومنھ ا تتفاعل عناصر الس بك م ع بعض ھا و فیوض ح البنی ة المجھری ة ) 10(أم ا الش كل ). alfesi(الط ور للسبیكة االساس بعد اجراء المعاملة الحراری ة المحلولی ة والتعتی ق عن د ق یم الص الدة العظم ى، حی ث یالح ظ ان الس بیكة عب ارة ع ن حبیبات ناعمة ومتجانسة نوع ُا م ا وت ؤدي المعامل ة الحراری ة ال ى عدة اطوار یختلف توزیعھا ونسب تواجدھا على وفق زمن ظھور حرارة التعتیق وھي طور االلمنیوم وطور السلیكون الذي ودرجة ) mg2si(یكون بشكل جس یمات خش نة وط ور المرك ب النترس ب ) 12و 11(الش كلین. ال ذي یك ون بش كل دق ائق ص غیرة ناعم ة دقائق یوض حان البنی ة المجھری ة للس بیكة االس اس والمق واة ب بع د المعامل ة ) %0.6(الزركونی ا ودق ائق االلومین ا وب نس اض افة الحراری ة المحلولی ة والتعتی ق عن د ق یم الص الدة العظم ى حی ث یالحظ ان السبیكة عبارة عن حبیبات متجانسة نوعُا ما فض ُال ع ن ) mg2si(كمیة االطوار داخل البنیة المجھریة ك الطور المترس ب وتوزی ع دق ائق ك ل م ن الزركونی ا ) alfesi(والط ور الث انوي .وااللومینا المشتتة داخل ارضیة السبیكة االساس .البنیة المجھریة للسبیكة االساس قبل اجراء المعاملة الحراریةیوضح -٩ شكل .حراریةالبنیة المجھریة للسبیكة االساس بعد اجراء المعاملة الیوضح -١٠ شكل 50μm 50μm 2011)( 78 90 ، صفحة3، العدد 7مجلة الخوارزمي الھندسیة المجلد حسین إبراھیم دمد عماسر 88 .من دقائق الزركونیا بعد اجراء المعاملة الحراریة المحلولیة) %0.6(البنیة المجھریة للسبیكة االساس المقواة بنسبة یوضح -١١ شكل .ا بعد اجراء المعاملة الحراریة المحلولیةمن دقائق االلومین) %0.6(البنیة المجھریة للسبیكة االساس المقواة بنسبة یوضح -١٢ شكل االستنتاجات .٦ :ان اھم االستنتاجات المستنبطة من خالل البحث ھي إن زم ن التعتی ق ال الزم للوص ول إل ى الص الدة العظم ى -١ للسبیكة األساس بعد المعاملة الحراریة المحلولی ة عن د درج ة والتعتی ق االص طناعي عن د درج ة ح رارة ) (c˚520ح رارة 170˚c) ( 8ھوhr).( أثبت ت نت ائج الفح ص بحی ود األش عة الس ینیة ظھ ور الط ور -٢ ف ي ك ل م ن الس بیكة األس اس والم ادة ) (alfesiالث انوي ) االص الد بالترس یب (المتراكبة بینما أدت المعاملة الحراریة ف ي البنی ة ) (mg2siو ) (mg2alإل ى ظھ ور األط وار تحس ن واض ح ف ي والتي ادت الى المجھریة للسبیكة األساس الخ واص المیكانیكی ة، فض ُال ع ن ظھ ور دق ائق ك ل م ن . في البنیة المجھریة للمادة المتراكبة وااللومینا الزركونیا أدت إضافة دقائق كل من االلومینا والزركونیا إلى زیادة ق یم -٣ الصالدة للسبیكة األساس وان قیـم الص الدة ت زداد م ع زی ادة .النسب المضافـة اوم ة الش د القص وى وإجھ اد الخض وع للم ادة إن ق یم مق -٤ المتراكبة أعلى مما ھو علیھ في السبیكة األساس وتزداد ھ ذه الق یم م ع زی ادة النس ب الوزنی ة لل دقائق المض افة وال ى ح د ثم تسلك المادة المتراكبة س لوكًا مغ ایرًا لكنھ ا تبق ى ) (0.6% ي محافظة على قیم أعلى مما ھو علیھ في الس بیكة األس اس ف حین تنخفض قیم المطیلیة للمادة المتراكبة مقارنة مع السبیكة األساس ویزداد انخفاضھا م ع زی ادة النس ب الوزنی ة لل دقائق . المضافة للسبیكة األساس أدت إضافة دقائق الزركونیا ودقائق االلومینا إلى تقلیل معدل -٥ وان النقصان , البلى للسبیكة األساس ومع تغیر الحمل المسلط . اد مع زیادة النسب المضافة من الدقائقیزد المصادر .٧ [1] g. piatti ,'' advance in composite materials" , applied science publishers ltd, (1978). 50μm 2011)( 78 90 ، صفحة3، العدد 7مجلة الخوارزمي الھندسیة المجلد حسین إبراھیم دمد عماسر 89 [2] j. w. weeton, m. p. dean, l.t. karyn, "engineering's guide to composite material", published by american society for metals,(1987). [3] d. hull ,'' an introduction to composite materials'', first published cambridge university press., u.k , (1981). [4] m.grayson, ''encyclopedia of composite material and components'', willey-inter science, (1993). [5] p.g. mickel, '' fundamentals of modern manufacturing '',new jersey (1996). [6] s.f. mustafa ,'' wear and wear mechanisms of (al-22%si ) al2o3 composite'', wear vol.185, (1995) 189. [7] m.e. smagorinski, s. greier, a. cavasin, and g. kim ,'' the properties and microstructure of al-based composite reinforced with ceramic particles '', j.mat. sci. and eng. a244 (1998). [8] j.e. perez and a.a. yawny, ''fracture toughness in metal matrix composite'', material research , (2000). [9] p.r. gibson, a.j. clegg and a.a. das, "wear of cast (al-si) alloys containing graphite '', wear vol. 95, (1984), 193. [10] c.s. sivaramakrishan , r.k. mahanti and r. kumar, '' the dispersion of lead and graphite in aluminum alloys for bearing application '', wear vol.1, (1984), 121. على دراسة تأثیر المعاملة الحراریة"اسراء عبد القادر، ]١١[ تحت ظروف ) سلیكون -األلمنیوم(مقاومة البلى لسبیكة ، مجلة الھندسة والتكنولوجیا، المجلد "االنزالق الجاف . ١٩٩٨، ١١العدد ١٧ )cu-al( تصلید سبیكة االلمنیوم"حازم محمد ناصر ]١٢[ قسم العلوم , رسالة ماجستیر" بواسطة تشتیت االلومینا .2001)( الجامعة التكنولوجیة, التطبیقیة تاثیر اضافة االلومینا على " عدنان ابراھیم الجرجري ]١٣[ ، "نحاسقابلیة االصالد بالتشتیت لسبیكة االلمنیوم الجامعة ،ھندسة االنتاج والمعادن ،رسالة ماجستیر . ٢٠٠١، التكنولوجیة دراسة الخواص المیكانیكیة "میرفت مھدي الجنابي ]١٤[ رسالة )"al-cu-mg(لمتراكبات ذات اساس سبیكة الجامعة التكنولوجیة,قسم العلوم التطبیقیة,اجستیرم )2005.( sarmad i. ibrahim al-khwarizmi engineering journal, vol. 7, no. 1, pp 78 90 (2011) 90 studying the effect of addition particles of alumina (al2o3) and zirconia (zro2), on some mechanical properties for matrix composites (al-si-mg) alloy sarmad i. ibrahim department of materials engineering\ university of technology abstract this study is concerned with the effect of adding two kinds of ceramic materials on the mechanical properties of (al-7%si0.3%mg) alloy, which are zirconia with particle size (20μm > p.s ≥ 0.1μm) and alumina with particle size (20μm > p.s ≥ 0.1μm) and adding them to the alloy with weight ratios (0.2, 0.4, 0.6, 0.8 and 1%). stirring casting method has been used to make composite material by using vortex technique which is used to pull the particles to inside the melted metals and distributed them homogenously. after that solution treatment was done to the samples at (520ºc) and artificial ageing at (170ºc) in different times, it has been noticed that the values of hardness is increased with the aging time of the original alloy and reached its highest value after (8hr). mechanical tests were done to the original alloy and the composite material at the maximum hardness value and represented by tensile, hardness, and wear tests. it was found that the hardness value is increased with increment of the amount of added particles; also the increment in the hardness of the alloy which is reinforced with alumina is more than that reinforced with zirconia. regarding the tensile test, results show that the strength and yield resistance of the composite material are more than that in the original alloy and these values are increased with increasing the amount of the added particles and they reached maximum values at (0.6%). then they are decreased but these values remain at higher values than those in the original alloy. however, the ductility is decreased as compared with the original alloy and this decrement was more obvious with the increasing amount of the added particles. the increment of strength and yield resistance of the alloy reinforced by alumina was higher than that reinforced with zirconia, while the ductility of the alloy reinforced by zirconia was higher than that happened by the addition of alumina. also zirconia and alumina addition to the original alloy decreased the wear rate, and the decrement would be more with the increased amount of adding particles. in addition the wear resistance of the alloy reinforced with alumina was larger than that reinforced with zirconia. x-rays testing proved that secondary phase (alfesi) appeared in both original alloy and the composite material. while heat treatment led to the appearance of phases (mg2al) and (mg2si) in original alloy. this was led to obvious improvement in the mechanical properties in addition to appearance ceramic particles in the microstructure of the composite material. this structure somewhat homogenous has fine grains as compared with large grains in the microstructure of the original alloy. . al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 7, no. 2, pp 75 82 (2011) effect of lanthanum addition on the microstructure of mg-4al alloy ahmed a. moosa department of production and metallurgy engineering/ university of technology email: ahmedmuot@yahoo.com (received may 2010; accepted 17 february 2011) abstract this research was to determine the effect of rare earth metal (rem) on the as-cast microstructure of mg-4al alloy. the rare earth metal used here is lanthanum to produce mg-4al-1.5la alloy. the microstructure was characterized by optical microscopy. the phases of this alloy were identified by x-ray diffraction. the microstructure of mg-4al consists of α-mg and grain boundaries with precipitated phase particles. with the addition of lanthanum, three distinct phases were identified in the x-ray diffraction patterns of the as cast mg-4al-1.5la: mg, al11la3, al4la. the mg17al12 phase was not detected. the addition of lanthanium increases the hardness and decrease the wear rate of mg-4al. keywords: metallic alloys, magnesium-aluminum-rare earth alloys, microstructure. 1. introduction light-weight magnesium alloys have attracted increasing interest in recent years for applications in the automotive, aircraft and electronic industries. magnesium alloy die-castings are very suitable for automotive applications because vehicle weight reduction and consequently energy saving are becoming the world focus. magnesium is onethird less dense than aluminum and four-fifths less dense than iron [1, 2]. a major development in creep-resistant magnesium alloys has been the emergence of rareearth (re)–containing alloys. this group of mgal-re alloys contains at least one and, in general, a mixture of re elements, as aprecipitate. this alloy system exhibits a major improvement in creep resistance. these alloys did not find their place in industry due to various reasons such as poor castability and low strength.[3,4] in mg-al-rem alloys however, under slow solidification rates (sand and permanent mold casting), it was discovered that the rare earth reacted preferentially with aluminum and favored al2re formation with no improvement in creep resistance. under die-casting conditions (higher solidification rates), al4re formation was favored and improved creep resistance was achieved [1, 5]. recently developed alloys containing one or more rare earths have been found to possess improved properties over the early mischmetal alloys like ae42 alloy (mg 3.74al 0.87ce 0.43 la -0.26 nd0.08 pr) [6]. the ae42 casting alloy (mg-4al-2rem) was developed for high temperature applications. aluminum is added to improve castability and room temperature mechanical properties while rem addition is for creep resistance. however, the properties of ae42 deteriorate rapidly when the temperature is above 150 °c. therefore, there still remains a limitation to its use at high temperatures [6]. a certain dependence of the solubility of rem in magnesium on the atomic size of lanthanides has been established. it correlates with the change in the atomic radii of rem, which grows with growth in the atomic number and closeness to the atomic radius of magnesium [7]. it is well established that rem of the yttrium subgroup (y, gd, and lu) posses a considerably higher solubility in solid magnesium than rem of the cerium subgroup (la, ce, pr,) [7, 8]. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ ahmed a. moosa al-khwarizmi engineering journal, vol. 7, no. 2, pp 75 82 (2011) 76 many studies have been conducted on the effects of re on microstructures of mg-rem alloys, but different phases were reported [9-12]. high-pressure die-cast mg–4al–4re–0.4mn (re = la, ce) magnesium alloys were studied by zhang et al.[13] . two binary al–ce phases, al11ce3 and al2ce, are formed mainly along grain boundaries in mg–4al–4ce–0.4mn alloy, while the mg–4al–4la–0.4mn alloy contains only αmg and al11la3. the results of the theoretical calculation showed that the stability of al11la3 is the highest among four al–re intermetallic compounds supports the experimental results further [13]. powell et al. [1] studied the microstructure and creep behavior in ae42 magnesium die-casting alloy. a lamellar-phase al11re3, which dominates the interdendritic microstructure of the alloy, partly decomposes above 150°c into al2re and al (forming mg17al12). die-cast mg –4al– 4re–0.4mn (re = ce-rich mischmetal) and mg –4al–4la–0.4mn magnesium alloys have been investigated by zhang et al.[14] . the results show that the two phases, al11re3 and al2re, are formed along grain boundaries in mg –4al–4re–0.4mn alloy, while the phase compositions of mg –4al–4la–0.4mn alloy mainly consist of αmg phase and al11la3 phase. the al11la3 phase occupies a large grain boundary area of the alloy microstructure and grows with complicated morphologies. li et al. [15] found that there are some grain refinement and thinning of β-mg17al12 phase in az91d alloy containing calcium (0.11.0 wt. %). increasing ca content resulted in the formation of al2ca phase as well as in the reduction in quantity of β-mg17al12 phase. the ultimate tensile strength and relative elongation worsened which was explained by the presence of al2ca phase on the grain boundaries. in this work rem, la, will be added to mg4al to study the influences of al–rem phases on the microstructures of mg-4al-1.5la cast alloy. 2. experimental methods the mg-al alloy (mg-4al) and mg-4al-1.5 la alloy were prepared from commercially pure ingots of magnesium, aluminum and lanthanum. to minimize the amount of inclusions or oxides films in the specimen during alloy preparation, a special melting crucible was used. a schematic drawing of the equipment used is shown in figure(1). each alloy was first prepared by melting the desired amount of materials in a stainless steel crucible in an electric resistance furnace under argon gas. two stainless steel crucibles were used, the inner melting crucible and the second outer crucible. the outer crucible has two tubes at the upper cover, one tube through which argon gas passes and the second tube for argon gas outlet. type -k thermocouple was inserted through the cover of the outer crucible for recording real temperature near inner crucible with a controlled temperature ± 2 °c. fig.1. schematic diagram for melting crucible for mg alloys. magnesium (99.5% purity), aluminum (99.9% purity) and lanthanum (99.9% purity, mti co. china) were used. each metal was weighed using digital balance (precisa, model xb220a, swiss) with accuracy ±100 µg. mg 4al – 1.5 la alloy was prepared by wrapping the magnesium and lanthanum in a piece of aluminum foil which was first put in the inner stainless steel crucible. this inner crucible was then put inside the outer stainless steel crucible. this combined system was then put in an electrical holding furnace under an argon atmosphere with a flow rate of 1.5 l /min . at 900◦c, the melt was purged for about 5 min. after purging, the melt was held for 15 min. the ingot was remelted three times under argon to insure homogeneity. the ingot was furnace cooled under argon atmosphere to room temperature. molten magnesium and its alloys are volatile substances that have a tendency to oxidize explosively in air and require surface protection in casting processes. thus, argon gas was used as a this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ ahmed a. moosa al-khwarizmi engineering journal, vol. 7, no. 2, pp 75 82 (2011) 77 cover gas for the molten magnesium alloys to prevent the rapid surface oxidation and possible burning or igniting explosively in air. each ingot was cut into 1cm x 1cm x 0.5cm and then cleaned with ultrasonic bath using alcohol. each sample was then ground using silicon carbide paper (200, 500,800, 1000 and 1200) grits , washed with water and then polished using cloth with alumina suspension (particle size 0.3 µm). samples were then ultrasonically cleaned , dried and then etched using enching solutions : glycol solution : 1 ml hno3 (conc.), 24 ml water, 75 ml ethylene glycol for (3-5) seconds and then with acetic-picral solution : 5 ml acetic acid, 6 gm picric acid, 10 ml h2o, 100 ml ethanol (95%)for (3-5) seconds [13]. the microstructure was analyzed by optical microscopy, (olympus, japan). vickers hardness test is done by using digital micro vickers hardness tester (type th715, beijing, time high technology ltd). for the purpose of accurate readings, an average of ten readings was taken at each point for each sample with 2.94 n load. the x-ray diffraction for mg-4al-re alloy was carried out using cu k radiation at 40 kv and 30 ma was (xrd 6000 shimadzu). the sample was machined in the form of disc (3.8 mm thickness and 10 mm diameter). in order to identify the phase present, the sample was continuously scanned within bragg angle range of (20-50°). dry sliding wear tests were conducted on mg4al and mg-4al-1.5la specimens on the pin-ondisc apparatus. the wear specimens were cylindrical with a diameter of 10 mm and a height of 20 mm. the specimen slides on a carbon steel disc with a hardness of 38 hrc. the applied load used in this test was 10 n. wear rate is calculated from the following formula wear rate (wr) = δw / 2πrnρtt …(1) and δw = w1 – w2 …(2) where wr : wear rate (cm3/cm) w1 : specimen weight before the wear test (gm). w2 : specimen weight after the wear test(gm). r : the distance from the center of the specimen to the center of the steel disc = 7 cm. n : the rotational speed for the steel disc = 277 rpm. ρt : the density of the mg-4al and mg-4al-1.5la alloy ( 1.745 and 1.844 gm/cm3 respectively). t : the sliding time = 10 minutes. 3. results and discussion 3.1. microstructure pure magnesium had long columnar grains growing from the edge toward the center. the addition of al caused significant grains refinement. addition of 4% al produced a transition to equiaxed grains and a significant reduction in grain size. the microstructure of mg4al alloy composed of the primary αmg matrix, and a secondary phase that exists in two kinds of morphologies, i.e., a discontinuous network of coarse particles along grain boundaries, and many spherical particles that distributed both inside grains and at grain boundaries as shown in figure.2. fig. 2. optical micrograph of as cast mg-4al alloy with α-mg plus al12mg17. aluminum increases the hardness of mg , with the strengthening effect being based on solidsolution formation α-mg and with large βphase particles, mg17al12 phase. this is in agreement with the findings of other studies [11, 12] where at high aluminum contents, an interdendritic mg17al12 grain boundary phase is formed, which lowers the strength at application temperatures beyond 120 °c. the weakening effect of the mg17al12 phase on the grain boundaries has been invoked as the limiting factor for creep resistance of az91alloy (mg-9al-1zn) as reported by fan et al.[11]. besides improving the mechanical properties, aluminum significantly enhances the castability of magnesium. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ ahmed a. moosa al-khwarizmi engineering journal, vol. 7, no. 2, pp 75 82 (2011) 78 chinese script is also observed in mg4al alloy as shown in figure 3. when a eutectic composition solidifies, both α and β solid phases must deposit on the grain nuclei until all of the liquid is converted to solid. this simultaneous deposition results in microstructures made up of distinctively shaped particles of one phase in a matrix of the other phase, or alternate layers of the two phases. chinese script is one of the characteristic eutectic microstructures. each eutectic alloy has its own characteristic microstructure when slowly cooled. more rapid cooling, however, can affect the microstructure obtained [16]. the addition of la to mg-4al alloy will lead to grain refinement as shown in figure 4. the mechanism of grain refinement by lanthanum has not been identified [17]. however, the effect of la on growth kinetics can be understood by the growth restriction effect of la rejected ahead of the solid/liquid interface. because its solid solubility in magnesium is relatively small, rapid enrichment of solute in the liquid ahead of the growing interface would be expected during solidification. gruzleski and aliravci [18] proposed a grain refinement mechanism in mg – sr system. in this mechanism, sr may poison the grain surface or poison the fast growing directions of the grains by preferential adsorption of sr at these sites. fig.3. optical micrograph of as cast mg-4al alloy showing chinese script. etched with (75glycol +24 h2o +1 hno3) solution. fig.4. mg-4al-1.5 la as cast alloy; a) showing mg, and other al-la compound ; b) higher magnification. 3.2. x-ray diffraction x-ray diffraction patterns of the mg 4al – 1.5 la alloy is shown in figure 5. three distinct phases were identified in the patterns: mg, al11la3, and al4la. the major phase is magnesium. although there is some disagreement in the literature as to whether al11la3 and al4la are the same phase [19, 20]. in this work they are different. details of the effects of rare earth additions on phases present in mg-alloys are listed in table 1. the formation of αmg and al11re3 phases in this work are in agreement with many researchers. the discrepancies are in the formation of al2re, al4re or al3re. the formation of either al11re3 or al4re is sensitive to the individual rare earth element as evidenced by a relationship between the relative amounts of al11re3 versus al4re. the mg17al12 phase was not observed in mg-4al1.5 la alloy. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ ahmed a. moosa al-khwarizmi engineering journal, vol. 7, no. 2, pp 75 82 (2011) 79 fig.5. x-ray diffraction of mg-4al-1.5 la. table 1, effect of rare earth addition on phases present in mg-4al alloys. referencephasesalloy sun et al. [ref. 12]mg, al11la3mg-4al -2reae42 fan et.al. [ref 11]mg, mg17al12, al11la3,al8lamn4mg-9al-0.7zn-2lazl2 powell et al. [ref. 1]mg, al11re3, al2remg-4al -2reae42 rzychoń et al. [ref.9]mg,mg17al12mg-4al -2reae42 rzychoń et al [ref.9]mg, al11re3, al3remg-4al -4reae44 zhou et al.[ref 10]mg, mg17al12,al4cemg-5.5al -1ce zhang et al.[ref 13]mg, al11la3mg-4al -4laae44 zhang et al.[ref 13]mg, al11ce3, al2cemg-4al -4ceae44 in order to suppress the eutectic reaction to form (mg17al12 ) phase in mg – al – la system , then the element la should react with aluminum and form an alzlaw intermetallic( where z,w are constants). this is true only if the affinity of the element la for al is higher than its affinity for mg; then the formation of alzlaw will be preferred to mgx lay. analyzing the known diagrams of binary mg – la and mg – al systems [16], it is clear that only rare-earth metals (re), alkaline-earth elements, and transition elements of the third group of the periodic system possess such affinity. the reason for the absence of mg17al12 in our results may be attributed to the higher content of rare earth elements (i.e., la) in the alloy. most al is present in the form of al11la3 and al4la, with little al sequestered as solute in the α-mg matrix. the maximum solid solubility of la in mg is about (0.79 wt %), consequently more la atoms are utilized in the formation of intermetallic compounds [13]. the solid solubility of rem in magnesium is very low, which is further reduced by the presence of al [14]. because of the high chemical stability of al11re3 and al4re phases, rare earths are combined with al and form al11re3 until all the available rare earths are used without any formation of pseudo-binary mg-re or mg-al phase or pseudo-ternary mg-alre phase [13]. depending on the composition, precipitates of other types of compounds have also been mentioned in the literature. pettersen et al. [21] suggested that when re/al weight ratio is above 1.4 all of the aluminum will be tied up as al11re3 in which case further precipitation of other phases such as anot pekguleryuz et al. [22] report that the alloys show different microstructures based on the sr/al ratio. for sr/al ratio below about 0.3, al4sr intermetallic is the only second phase in the this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ ahmed a. moosa al-khwarizmi engineering journal, vol. 7, no. 2, pp 75 82 (2011) 80 structure. when the sr/al ratio is higher, a second intermetallic phase (a ternary mg-al-sr phase) is also observed. sr/al controls the formation of mg17al12 as well. when the sr/al ratio is very low, there would be insufficient amount of sr to bind all al and the excess al would form the mg17al12 phase. in the alloy of this research more aluminum atoms were consumed by the formation of al11la3 and al4la phases. it leads additionally to decreasing of aluminum content in solid solution α-mg and this alloy probably will be better to work at elevated temperature, her type of al-re phase or mg12re becomes possible. 3.3. hardness and wear rate the hardness of mg-4al and mg-4al -1.5 la alloys were measured using vickers hardness (2.94 n). the overall hardness of mg-4al increases with la addition as shown in figure 6. the increase in the hardness due to la addition is due to the refining of the microstructure due to nucleation of al11 la3 phases. the wear rate of mg-4al and mg-4al -1.5 la alloys were measured using pin on disk apparatus. the load applied is 10 n and the duration is 10 min. it is clear from figure 7, that the wear rate for mg-4al -1.5 la is lower than that for mg-4al. this is in agreement with the hardness measurement where the la addition increases the hardness of the alloy. fig.6. vickers hardness of mg-4al and mg-4al1.5la alloys. fig.7. wear rate of mg-4al and mg-4al-1.5la alloys. 4. conclusions 1in the as-cast condition the microstructure of mg-4al alloy consists of primary αgrains with the grain boundaries precipitates of large βphase particles. 2the addition of lanthanum refined βphase and formed al11la3 strengthening phase, which improved the hardness and wear resistance of the mg-4al1.5la alloy. 3with the addition of lanthanum, the mg17al12 phase was not detected. 5. references [1] bob r. powell, vadim rezhets, michael p. balogh, and richard a. waldo, microstructure and creep behavior in ae42 magnesium die-casting alloy, j. of metals , vol.54 , august 2002, pp.34-38 [2] y. xu, l.s. chumbley, g.a. weigelt, and f.c. laabs, analysis of interdiffusion of dy, nd, and pr in mg, j. mater. res., vol. 16, no.11, nov. 2001, p. 3288 [3] m.o. pekguleryuz and a.a. kaya: in magnesium alloys and their applications, k.u. kainer, ed., wiley-vch verlag gmbh, germany, 2003, pp. 74–93. [4] f. khomamizadeh, b.nami, and s. khooshkhooei , effect of rare-earth element additions on high-temperature mechanical this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ ahmed a. moosa al-khwarizmi engineering journal, vol. 7, no. 2, pp 75 82 (2011) 81 properties of az91 magnesium alloy, metallurgical and materials transaction a, vol. , 36a, dec., 2005, pp. 3489-3494. [5] e.g. sieracki, j.j. velazquez, and k. kabiri, “compressive stress retention characteristics of high pressure die cast magnesium alloys,” sae technical publication no. 960421 (warrendale, pa: tms, 1996). [6] a. a. luo, and m. o. pekguleryuz, “cast magnesium alloys for elevated temperature applications,” j. mat. sci., vol. 29, 1994, pp. 5259-5271. [7] l. l. rokhlin, magnesium alloys containing rare earth metals.structure and properties, taylor and francis, london – newyork (2003). [8] l. l. rokhlin , structure and properties of alloys of the mg-rem system , metal science and heat treatment, vol. 48, nos. 11 – 12, 2006, pp. 487-490. [9] t. rzychoń, a. kiełbus ,effect of rare earth elements on the microstructure of mg-al alloys, journal of achievements in materials and manufacturing engineering,vol. 17,no. 1-2, julyaugust,2006, pp. 149-152. [10] h. zhou, x. zeng, l. liu, y. zhang, y. zhu, w. ding, effect of cerium on microstructures and mechanical properties of az61 wrought magnesium alloy, j. of mat. sci. vol. 39, 2004, pp.7061 – 7066. [11] y. fan , g. wu , h. gao , g. li , c. zhai, influence of lanthanum on the microstructure, mechanical property and corrosion resistance of magnesium alloy , j. mater sci, vol. 41,2006, pp. 5409–5416. [12] y. sun, s. xue, j. bai, f. xue, heat resistant magnesium alloys with rare earth and alkaline additions, materials forum ,vol.29 , 2005 , pp. 311-317. [13] j.zhang , d.zhang , z.tian , j.wang, k.liu , h. lu, d.tang , j.meng, microstructures ,tensile properties and corrosion behavior of die cast mg-4albased alloys containing la and /or ce , j. mater. sci. eng. a, vol., 489, 2008, pp.113119. [14] j. zhang, p. yu, k. liu, d. fang, d. tang, and j. meng, effect of substituting ceriumrich mischmetal with lanthanum on microstructure and mechanical properties of die-cast mg –al–re alloys, materials and design, vol.30,no.7, august 2009, pp. 2372-2378 . [15] p. li, b. tang, e.g. kandalova, microstructure and properties of az91d alloy with ca additions, materials letters, volume 59, issue 6, march 2005, pp. 671675. [16] asm. vol.9, “metallography and microstructures” and vol.3 "alloy phase diagrams" metal park oh, usa. 2004. [17] y.c. lee, a.k. dahle, and d.h. stjohn, “the role of solute in grain refinement of magnesium”, metallurgical and materials transaction a, vol. 31a, nov. 2000, pp. 2895-2909. [18] j.e. gruzleski and c.a. aliravci: low porosity, fine grain sized strontiumtreated magnesium alloy casting, u.s. patent no. 5,143,564, 1992. [19] l.y. wei and g.l. dunlop: “precipitation hardening in a cast mg-rare earth alloy,” magnesium alloys and their applications, ed. b.l. mordike and f. hehmann , verlag, germany,1992, pp. 335–342. [20] a.h. gomes de mesquita and k.h.j. buschow, “the crystal structure of socalled alpha-laal4,” acta cryst., 22 (1967), pp. 497–501. [21] g. pettersen, h. westengen, r. hoier and o.lohne, microstructure of a pressure die cast magnesium-4wt.% aluminium alloy modified with rare earth additions“, mat. sci. and eng., a207, 1996, pp. 115-120. [22] m. pekguleryuz, p. labelle, e.baril, d. argo, ‘’magnesium diecasting alloy aj62x with superior creep resistance and castability,” 2003 magnesium technology, tms, san diego, march 2003, pp. 201207. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ 82 ، صفحة2، العدد 7مجلة الخوارزمي الھندسیة المجلد احمد علي موسى 75 )2011( 82 المنیوم %٤ على خصائص سبیكة المغنسیوم اللنثانیومتاثیر اضافة معدن احمد علي موسى الجامعة التكنولوجیة/ والمعادن اإلنتاجقسم ھندسة ahmedmuot@yahoo.com: البرید االلكتروني الخالصة ة وأنتاج سبیك أو احتراقھوالحیلولة دون اكسـدة المغنیسیوم (mg-4al)سبائك تاثیر اضافة عناصر االرض النادرة على یھدف ھذا البحث الى دراسة (mg-4al-1.5 la). .mg-4al-1.5 la)( كما تضمن البحث الفحوصات المجھریة وفحص األشعة السینیة لمعرفة األطوار الناتجة في سبیكة .مع وجود ترسبات على الحدود البلوریة ) α mg (الطور تحتوي على mg-4al)( أن سبیكةأظھرت النتائج mg-4al-1.5)( سبیكة في ر االطوااما la ي ور mg, al11la3, al4la .فھ ور الط دم ظھ ع ع ى . mg17al11م ؤدي ال انیوم ی افة اللنث ان اض . زیادة الصالدة وانخفاض معدل البلى this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ زينب حسون وزينب حسن al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 8, no. 4, pp 62-73 (2012) experimental investigation of using evaporative air cooler for winter air-conditioning in baghdad zainab hasson hassan zainab hassan hanash department of machine and equipment engineering/ university of technology (received 2 april 2011; accepted 7 august 2012) abstract this paper presents an efficient methodology to design modified evaporative air-cooler for winter air-conditioning in baghdad city as well as using it for summer air-conditioning by adding a heating process after the humidification process. laboratory tests were performed on a direct evaporative cooler (dec) followed by passing the air on hot water through heat exchanger placed in the coolers air duct exit. the tests were conducted on the 2nd of december /2011 when the ambient temperature was 8.1°c and the relative humidity was (68%). the air flow rate is assumed to vary between 0.069 to 0.209 kg/s with constant water flow rate of 0.03 kg/s in the heat exchanger. the performance is reported in terms of effectiveness of dec, saturation efficiency of dec, outlet temperature of air and cooling capacity. heat transfer rate in heat exchanger mode is also estimated. the paper presents the mathematical development of the equations of thermal exchanges through dec and he. prediction of air condition that exits o this system show that the present system could bring the air stream to a comfortable winter zone . key words: evaporative air cooler, winter air-conditioning, heat transfer, heat exchanger. 1. introduction refrigerated air conditioners can be used for both winter and summer air-conditioning, but their energy consumption is high. sometimes, partially effective systems yield the best results in terms of comfort and cost. evaporative air conditioning systems are inexpensive and offer an attractive alternative to the conventional summer air conditioning systems in places, which are hot and dry. since the conventional evaporative air cooler (eac) is not suitable for winter airconditioning because it would lower the temperature to an inconvenient level, the present work aims to investigate the possibility of modifying the system by equipping it with a heating element. the average temperature for iraq varies from higher than 48 ºc (120 fahrenheit) in july and august to below freezing in january. the long-term averages of monthly climatic conditions in iraq are summarized in figure 1.the required winter air-conditioning process in this work consists of: an evaporative cooling process which preformed through the using the eac and a sensible heating process can be achieved by passing hot water through a heat exchanger inserted into the eac's outlet air duct. the literatures regarding the use of evaporative cooling and conventional (eac) for summer air conditioning are many [1-4], but the literatures that deal with using eac for winter air – conditions are few [5-6]. the present work presents the results of a laboratory tests that assessed the effectiveness of the modified evaporative air cooler eac for cold winter in baghdad. the test was conducted in the morning of 2 nd of december when the ambient temperature was 8.1ºc and humidity ratio was about 68%. the laboratory tests were performed by passing hot water through a heat exchanger placed in the delivery duct of air cooler. the flow rate of the hot water was constant while different air mass flow rate were taken. these tests showed that the system could bring the air stream to a comfortable condition. this paper develops a mathematical model for both a direct evaporative zainab hasson hassan al-khwarizmi engineering journal, vol. 8, no.4, pp 6273(2012) 63 cooling (dec) system and heat exchanger (he) process. a test rig was designed and fabricated to collect experimental data in the air conditioning laboratory at the university of technology, mechanical engineering department, in bagdad. 2. experimental work 2.1. direct evaporative cooling the principle underlying direct evaporative cooling is the conversion of sensible heat to latent heat. non-saturated air is cooled by heat and mass transfer increases by forcing the movement of air through an enlarged liquid water surface area for evaporation by utilizing blowers or fans. some of the sensible heat of the air is transferred to the water by evaporating some of it. the latent heat follows the water vapor and diffuses into the air [8]. fig. 1. climate conditions in iraq [ 7]. figure 2 shows a schematic direct evaporative cooling system, where water is running in a loop and the makeup water entering the sump to replace evaporated water must be at the same adiabatic saturation temperature of the incoming air. in a dec, the heat and mass transferred between air and water decreases the air-dry bulb temperature (dbt) and increases its humidity, keeping the enthalpy constant (adiabatic cooling) in an ideal process. the minimum temperature that can be reached is the thermodynamic wet bulb temperature of the incoming air. the effectiveness of this system is defined as the rate between the real decrease of the dbt and the maximum theoretical decrease that the dbt could have if the cooling were 100% efficient and the outlet air were saturated. practically, wet porous materials or pads provide a large water surface in which the air moisture contact is achieved and the pad is wetted by dripping water onto the upper edge of vertically mounted pads. fig. 2. direct evaporative cooling (dec). 2.2. heat exchanger a space radiator of which a water-to-air compact heat exchanger was used as a compact heat exchanger in this work.. in a space radiator, heat is transferred from the hot water flowing through the radiator tubes to the air flowing through the closely spaced thin plates outside attached to the tubes. in compact heat exchangers, the two fluids usually move perpendicular to each other, and such flow configuration is called crossflow. both fluids are unmixed in a space radiator. the radiator has 20 tubes of internal diameter 1.02 cm and a wall thickness 0.9 mm. the length of the heat exchanger in the direction of the air flow is 65 cm. the tubes are in a closely spaced platezainab hasson hassan al-khwarizmi engineering journal, vol. 8, no.4, pp 6273(2012) 64 finned matrix of (0.25×0.25) m, as shown in figure 3. the radiator was placed at the front opening of the air-cooler duct. two valves were placed before and after the heat exchanger. the hot water is coming from a storage tank. these systems heat and store water in a tank so that hot water is available at any time. hot water enters the tubes at 90ºc at a rate of 0.03 kg/s. as hot water is drawn from the top of the tank, cold water enters the bottom of the tank and is heated. the heating source in this work is electricity. radiator is designed to heat the air stream coming from the dec. it do this by drawing cold air in at the bottom, warming the air as it passes over the radiator, and discharging the heated air at the top as shown in figure 4. this sets up convective loops of air movement within a space. fig. 3. a space radiator. fig. 4. convective loops of air flow from radiator. 3. the experimental setup an experimental study was performed during the winter at the laboratory of air conditioning and refrigeration of the mechanical engineering department in the university of technology in baghdad on the second of december/2011. the test rig shown in figure 5 consists of a variable speed fan blows air through a 254 mm square duct of a direct evaporative air cooler. the air-cooler was run for an adequate time to reach steady state. the cold outdoor air is first filtered and then is brought in contact with the wetted surface. the equipment utilizes an evaporative pad with 230×230 ×150 mm, and provides about 370 m2 of evaporative surface area per cubic metre of media [9],providing a wetted area equal to 2.93 m2 in the pad. the air gets cooled due to simultaneous transfer of sensible and latent heats between air and water. the cooled and humidified air is then heated by using the heat exchanger (radiator), which increase the sensible heat. the hot water is coming from` an insulated storage tank. the top valve was then opened fully, allowing the hot water to run through the heat exchanger. the flow of water was controlled by adjusting the bottom valve's opening. the heat exchanger was placed at the front opening of the air-cooler duct supplying to the conditioned space. the measuring instruments included a normal thermometer to measure the inlet and outlet of hot water temperature and an electronic humidity-and-temperature meter to measure the properties of: ambient air which represents the evaporative cooler inlet, evaporative cooler outlet and a heat exchanger outlet which represent the conditioned space. zainab hasson hassan al-khwarizmi engineering journal, vol. 8, no.4, pp 6273(2012) 65 fig. 5. the test rig. table 1 shows the results of the test conducted on the 2 nd of december when the ambient temperature (t1) was 8.1 o c and the relative humidity (rh1) was 68%, the hot-water temperature was 90 o c for different mass flow rates of air. table1, the experimental data for inlet conditions and properties for dec and he. inlet conditions t1=8.1°c , rh1=68% , tw1=5°c ma(kg/s) t2(°c) r.h2(%) tw2(°c) t3(°c) r.h3(%) tw3(°c) 0.069 5.2 95.2 4.8 21.2 42.5 13 0.095 5.7 94.8 5.1 21.0 42.1 12.8 0.139 5.9 94.4 5.3 20.8 41.7 12.4 0.177 6.3 93.7 5.5 20.3 41.3 12.1 0.209 6.6 93.1 5.7 19.8 41.0 12.0 4. mathematical model 4.1. direct evaporative cooling analysis in this work the humid air is considered as a mixture of two gases: the dry air and water vapour. considering the humid air flow close to a wet surface, according to figure 6, the heat transfer will occur if the surface temperature ts is different from the draft temperature t. if the absolute humidity (concentration) of the air close the surface ws is different from the humidity of centrifugal fan of air cooler filter of air air duct humidifie r heat exchanger hot water storage tank zainab hasson hassan al-khwarizmi engineering journal, vol. 8, no.4, pp 6273(2012) 66 the draft w a mass transfer will also occur. the elementary sensible heat is [8] : δqs =hc da(ts-t ) …(1) the hc coefficient is determined from the nusselt number (nu) expressed as a function of the reynolds number (re) and prandtl number (pr). in a similar way the rate of water vapour transfer dmv between the draft and the air close to the surface will be : dmv =hm da(ws-w) …(2) by analysis of the interface air–liquid, the latent heat δql is determined by the energy conservation law. δql =δq-δqs =hlvsdmv …(3) rearranging eqs. (1)–(3), the total differential heat flow is : δq = [hc(ts-t + ) ρwhlvshm(ws-w)]da …(4) eq. (4) indicates that the total heat transfer is a result of heat transfer due to temperature difference and due to the difference of the absolute humidities. these two potentials can be combined by the lewis relationship so that the total heat flow will be expressed by a single potential that is the enthalpy difference between the air close to the wet surface and the air free current. using the specific enthalpy of the mixture as the sum of the individual enthalpies [10] gives: hs-h = (hsa-ha)+(wshvs-whv ) …(5) with the hypothesis that air and vapour are perfect gases it follows that: hs-h = cpu(ts-t) +hvs(ws-w) …(6) where the humid specific heat is: cpu = cpa+ wcpv …(7) in the standard environmental conditions cpa=1006 j/ kg k and cpv=1805 j/kg k. therefore [12]: ts-t = [(hs-h)-hvs(ws-w)]/cpu …(8) combining eqs. (4) and (8) gives: )}( )( ){( vslvs s s pu c lehh le ww hh c dah q − − +−=δ …(9) where le is the lewis relationship, a dimensionless number expressed as: le =hc /hmcpuρ …(10) in the above deduction the density of the humid air was approximated by the density of the dry air. taking the lewis relationship as being unitary, gives (hlvs-hvs)≈hls. it is also verified that the term (w-ws)hls is usually negligible in the presence of difference of the specific enthalpies (hs-h),so that only the first term inside brackets is significant. in the same way, the total heat flow is caused by the difference of specific enthalpies of the air and of the saturated air close to the wet surface and is given by: δq=hcda (hs-h)/cpu …(11) the sensible heat transferred is: δqs =macpudt … (12) therefore, by combining eq. (12) with eq. (1) gives: hcda(ts-t)=macpudt …(13) this can be integrated, resulting in:         −= − − − pua c s cm ah tt tt exp1 1 21 …(14) the effectiveness of direct evaporative cooling equipment is defined as: stt tt − − = 1 21ε …(15)         −−= pua c cm ahexp1ε ...(16) analyzing eq. (15) it is verified that an effectiveness of 100% corresponds to air leaving the equipment at the wet bulb temperature of entrance. this requires a combination of large area of heat transfer and a high heat transfer coefficient and low mass flow. it is also observed that the effectiveness is constant if the mass flow is constant since, it controls directly and indirectly the value of the parameters on the eq. (16). the flow rate of supply air should be such that when released in to the conditioned space, it should be able to maintain the space at satisfactorily condition, and offset the sensible and latent heat losses. the amount of supply air required (ma) can be obtained by using the following equation: ma = ρauaw …(17) zainab hasson hassan al-khwarizmi engineering journal, vol. 8, no.4, pp 6273(2012) 67 fig. 6. schematic direct evaporative cooler. heat transfer coefficient estimation dowdy and karabash [11] presents a correlation to determinate the convective heat transfer coefficients in a rigid cellulose evaporative media: 3/18.0 12.0 prre1.0      = l l nu c …(18) in dec state, rectangular, pad of rigid cellulose material are considered as cooling media. wetted surface area of cellulose material is assumed to as 370 m2/m3 [12]. total wetted surface area of each pad is given by: aw = vp as …(19) the characteristic dimension of the pad is: w p c a v l = …(20) this parameter is called characteristic length and is used to calculate the reynolds (re) and nusselt (nu) numbers. ν cul =re …(21) so the convective heat transfer coefficient can be calculated from: k lhnu cc= …(22) the following air properties: k= 0.0263 w/m °c; pr=0.708; cpu=1033 j/kg °c and ν=15.8×10-6m2/s at the inlet air temperature are used. table 2 shows the resulting convective heat transfer coefficient for several air velocities calculated from eq. (22). table 2, convective heat transfer coefficient for several air speeds. ma(kg/s) u(m/s) re hc(w/m2.cº) 0.069 1.1 191 35.47 0.095 1.5 261 45.46 0.139 2.4 417 66.26 0.177 2.9 504 77.11 0.209 3.3 573 85.44 4.2. heat exchanger analysis the characteristics of fluids contribute to a fundamental property of heat exchangers is the heat transfer rate (q). the heat transferred to the colder fluid(air) must equal that transferred from the hotter fluid(water), according to the following equation [13]: q = [ma × cp × (tout – tin)]cold = – [mw × cpw × (tout – tin)]hot …(23) the rate of heat transfer in this radiator from the hot water to the air is determined from an energy balance on air flow, q= [ma cp (tin tout)]air …(24) the tube-side heat transfer area is the total surface area of the tubes, and is determined: ao= nπdo l …(25) knowing the rate of heat transfer and the surface area, the overall heat transfer coefficient on the air side can be determined from: uo=q/ ao δtlm …(26) where δtlm is the log mean temperature difference for the counter-flow arrangement: 2 1 21 ln t t tttlm ∆ ∆ ∆−∆ =∆ …(27) where; δt1 = th, in tc, out …(28) δt2 = th, out tc, in …(29) the overall heat transfer coefficient of the outside air is calculated from eq.(26). zainab hasson hassan al-khwarizmi engineering journal, vol. 8, no.4, pp 6273(2012) 68 5. results and discussion two modes of test were conducted namely: evaporative cooling process through dec and heating process through h.e. 5.1. saturation effectiveness for dec mode the effectiveness of dec for different air mass flow rate is shown in figure 7. in direct cooling mode, saturation efficiency ranges from 80.1 % to 68.6 % for air mass flow rate of 0.069 to 0.209 kg/s for rectangular pad shape. it decreases for increase in air mass flow rate because at higher velocities, air has lesser contact time with water causing less evaporation. fig. 7. variation of saturation effectiveness . 5.2. cooling capacity for dec mode cooling capacity in direct cooling mode can be estimated in the following manner [14]. qc = ma cpu(t2–t1) …(30) cooling capacity for different air mass flow rate is shown in figure 8 . it depends on mass flow rate of air and temperature drop. dec cooling capacity ranges from 221 to 370 w for mass flow rate. the general trend is that cooling capacity increases with air mass flow rate. the values are compared well with those obtained in the literature [12]. fig. 8. variation of cooling capacity. 5.3. heat transfer rate and the overall heat transfer coefficient for he mode both the heat transfer rate of he mode calculated from eq.(24) using the air side and the overall heat transfer coefficient calculated from eq.(26) are shown in table 3 for different air mass flow rate. the values of heat transfer rate (figure 9) and the overall heat transfer coefficient of the air side are increased with increasing the mass flow rate of air for constant water flow rate in the radiator. table 3, heat transfer rate and overall heat transfer coefficient for several air mass flow rate. ma(kg/s) q(w) uo(w/m-2cº-1) 0.069 1140.4 40.4 0.095 151.3 57.3 0.139 2139.4 75.8 0.177 2559.7 90.7 0.209 2849.8 101.1 5.4. outlet air dry temperature from he mode the outlet dry temperature from the radiator is decreased with increasing the air mass flow rate as shown in figure10 because air has lesser contact time with hot water in the radiator for the same inlet temperature of water. the values of these temperatures showed that the present system zainab hasson hassan al-khwarizmi engineering journal, vol. 8, no.4, pp 6273(2012) 69 succeed to achieve comfortable condition for air flow for winter air-conditioning in baghdad. fig. 9. variation of heat transfer rate. fig. 10. variation of dry outlet temperature. 5.5. thermal comfort: pyschometry and thermodynamics the psychometric analysis provides more details on the actual process of changing the dbt and rh values, during the winter air conditioning process. this analysis not only provides the thermal comfort range but also, describes the actual implementation associated efficiencies. changing the inlet air condition from state 1 to state 3 can be done through an evaporative cooling system, followed by sensible heating process shown schematically in figure 11, for ma=0.095 kg/s along with its psychometric trace. following the psychometric trace; the ambient air enters through dec (state 1) (t1=8.1ºc &rh=68%) under adiabatic cooling and humidification process (1→2) and air leaves the dec at state (2) (t2=5.2ºc &rh=97%). then the cold air enters to the heat exchanger (radiator), heat is added to the air through the radiator (2→3). in this analysis the heat exchanger will be used to achieve the temperature and relative humidity for air at state (3) (t3=20.2ºc &rh=42%), which raises the dbt and reduces rh, in order to achieve a more comfortable condition. the warm air exit from heat exchanger (state 3) is bringing the cold air to winter comfort zone. in the same manner, presented the states on psychometric chart for different air mass flow rate. the electricity consumption of this air-cooler is considerably lower than that required by a refrigerated system. the cost of water consumed by the evaporative air coolers adds only a minimal cost to their operation. a study performed at the university of arizona, that compared the combined electrical and water consumption of evaporative coolers with the electrical consumption of central refrigerative air conditioners, found that that the typical evaporative cooler consumed about 1500 kwh of electricity per summer, costing about $150 [15]. the cooler’s water consumption added an average of $54 to a municipal water bill over the course of the summer, giving an electricity-and-water total of $204. by comparison, the central air conditioners consumed an average of 6000 kwh of electricity per summer, or about $600. the $400 saved annually by the evaporative cooler makes it an attractive option not only for the residents of arizona but for all families across the hot country. zainab hasson hassan al-khwarizmi engineering journal, vol. 8, no.4, pp 6273(2012) 70 6. conclusion in the present work, the required winter airconditioning process consists of an evaporative cooling process followed by a sensible heating process which can be achieved through the use of direct evaporative air cooler followed by heat exchanger placed into the dec outlet. the psychometric and thermodynamic analyses showed that the test of the present system could bring the air stream to the winter thermal comfort zone. the data acquired by experiment were analyzed by plotting the curves between various performance parameters. the theoretical model can be used to predict the performance of modified indirect evaporative cooler. the proposed system maks a good use of dec in winter as well as in summer because the evaporative cooler makes it an attractive option across hot weather areas. also the present system can be used not only in baghdad city, but in other cities which have the same weather. fan evaporato r heat exchange state ambaint state state winter comfort zone fig. 11. representation of the experimental result. zainab hasson hassan al-khwarizmi engineering journal, vol. 8, no.4, pp 6273(2012) 71 list of symbols a area of the heat transfer surface; total wetted surface area (m2) cpa constant pressure specific heat of the dry air (j /kg.k) cpu specific heat of the humid air (j /kg. k) cpv constant pressure specific heat of the vapour (j /kg. k) ha specific enthalpy of the air (j/kg) hc convective heat transfer co-efficient (w/ m2.°c) hlvs specific enthalpy of vaporization of the water at surface temperature (j /kg) hm mass transfer co-efficient (kg/ m2. s) hsa specific enthalpy of the leaving air (j /kg) hv specific enthalpy of the vapour (j/ kg) hvs specific enthalpy of the vapour at surface temperature (j /kg) l pad thickness (m) le characteristic length (m) l heat exchanger length (m) le lewis relationship (dimensionless) ma air mass flow (kg/ s) mv mass flow of the water vapour (kg/ s) nu nusselt number (dimensionless) pr prandtl number (dimensionless) qc cooling capacity of evaporative cooler (w) q heat transfer rate of heat exchanger (w) re reynolds number (dimensionless) rh relative humidity of air (%) t dry bulb temperature of air (°c) ts surface temperature (°c) u air speed (m/s) uo overall heat transfer coefficient (w/m2.cº) vp volume occupied by the evaporative pad (m3) w absolute humidity of the draft (kgw/kgair) ws absolute humidity of the air close the surface (kgw /kgair ) greek symbols ε cooling effectiveness (dimensionless) δtlm log mean temperature difference ρ density (kg/ m3) abbreviations eac evaporative air cooler dec direct evaporative cooling dbt dry bulb temperature he heat exchanger 7. references [1] kachhwaha s.s.and suhas p.;" heat and mass transfer study in a direct evaporative cooler"; journal of scientific and industrial research (2010);vol.69; september, pp.705710, [2] roberts, p. evaporative air conditioner study, joint project between yarra valley water and water services association of australia; internet www.com.au/nr/rdonlyres//eacr; (2009). [3] raskovic, p.o, g.d. vuckovic, m.v. vuklic;" improving eco-sustainable characteristics and energy efficiency of evaporative fluid cooler via experimental and numerical study"; thermal science;(2008); vol. 12; no. 4; 89-103. [4] qureshi, b.a. s.m. zubair;" a comprehensive design and rating study of evaporative coolers and condensers"; part i. performance evaluation. international journal of refrigeration;(2006);vol.29;pp. 645-658. [5] greenheckco.internet: www.greenheck.com/pdf/energy/hrecatalo gfebruary2005.pdf, (2009). [6] m.m.el-awad and m.m.ahmed;" a preliminary investigation into the use of evaporative air coolers for winter airconditioning in khartoum"; international conference and exhibition on green energy & sustainability for arid regions & mediterranean countries;(2009);november;pp.10-15. [7] weather and climate in iraq ,www.southtravls.com/middleeast/iraq/(2011 ). [8] j.r. watt, w.k. brown;" evaporative air conditioning handbook";3rd, the fairmont press, lilburn; ga;(1997); pp. 507. [9] ku¨u¨ l pads, available in www.kullpads.com;(2003). http://www.com.au/nr/rdonlyres//eacr; http://www.greenheck.com/pdf/energy/hrecatalo http://www.southtravls.com/middleeast/iraq/(2011 http://www.kullpads.com;(2003) zainab hasson hassan al-khwarizmi engineering journal, vol. 8, no.4, pp 6273(2012) 72 [10] j.r.s. moreira;" fundamentals applicators psicrometria"; rpa editorial ltda, sao paulo,(1999). [11] j.a. dowdy, n.s. karabash;" experimental determination of heat and mass transfer coefficient in rigid impregnated cellulose evaporative media"; ashrae trans 93 (part 2);(1987);pp. 382–395 . [12] camargo j.r.; ebinuma c.d.; siveria j.l.;" experimental performance of a direct evaporative cooler operating during summer in brazilian city. int. j. of refrigeration;(2005); 28(7), pp.1124-1132. [13] dean a. bartlett;"the fundamentals of heat exchanger, american institute of physics";(1996);pp.18-21. [14] watt j.r.; brown w.k.;" evaporative airconditioning handbook"; 3rd (1997). the fairmont press, inc. lilburn7. [15] saturn resource management,inc.internet;www.srmi.biz."l ow cost cooling evap.coolers cost less than ac";htm.(2009). http://www.srmi.biz )2012( 62-73، صفحة 4، العدد8مجلة الخوارزمي الھندسیة المجلد زینب حسون حسن 73 في بغداد دراسة عملیة باستخدام مبردة الھواء التبخیریة لغرض تكییف الھواء شتاءًا زینب حسون حسن زینب حسن حنش الجامعة التكنولوجیة /قسم ھندسة المكائن والمعدات الخالصة ویتم ذلك بإضافة ،تدفئة في فصل الشتاء وبما یالئم المناخ في مدینة بغدادھذا البحث یقّدم نموذج بسیط وفّعال لتطویر مبردة ھواء لغرض استخدامھا لل حیث تتكون ھذه المنظومة من مبردة ھواء مرتبطة ،تم تصمیم وبناء منظومة لھذا الغرض واخذ القراءات المختبریة. عملیة تسخین بعد عملیة الترطیب c°8.1حیث كانت درجة حرارة الھواء 2011تجارب في الثاني من شھر كانون الثاني لسنة تم أجراء ال. مبادل حراريبمجرى للھواء مّيبت في نھایتھ تم . kg/s 0.03مع ثبوت تدفق الماء للمبادل الحراري to 0.209 kg/s 0.069 ومعدل تدفق الھواء الداخل للمنظومة تتغیر بین % 68والرطوبة النسبیة وكذلك تم حساب انتقال وسعة التبرید درجة حرارة الھواء الخارج من المنظومة، كفاءة مبردة الھواء، الھواءالحصول على النتائج على ھیئة فعالیة مبردة على ضوء النتائج . ان ھذا البحث یقدم نموذج ریاضي لمعادالت التبادل الحراري خالل مبردة الھواء والمبادل الحراري. الحرارة خالل المبادل الحراري تم الحصول على ظروف مریحة للھواء لفصل فقد أثبتت ھذه المنظومة فعالیتھا وكفاءتھا حیث ،التي تم الحصول لظروف الھواء عند خروجھ من المنظومة .الشتاء غيداء al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 8, no.4, pp 2639 (2012) the effect of doppler phenomenon on the speed of blood flow ghaidaa abdulrahman khalid department of medical instrumentation engineering/ electrical and electronic techniques collegebaghdad email: ghaidaa85@yahoo.com (received 29 april 2012; accepted 6 september 2012) abstract this research studying the phenomenon of doppler (frequency doppler) as a method through which the direction and speed of the blood cells flows in blood vessels wear measured. this doppler frequency is relied upon in medicine for measuring the speed of blood flow, because the blood flow is an important concept from the concepts of medicine. it represents the function and efficient of the heart and blood vessels in the body so any defect in this function will appear as a change in the speed of blood flow from the normal value assumed. as this speed changes alot in cases of disease and morbidity of the heart, so in order to identify the effect of changing the doppler frequency on the speed of blood flow and the relationship of this frequency with the angles of transitions and receptions and the effect of changing the ultrasound transmitted frequencies on the measured velocities .the doppler ultrasound system has been used which is more efficient and easier to be widely used as a practical application in al yarmouk teaching hospital on two subjects. the normal had a natural medical history in the blood vessels, and abnormal had carotid artery stenosis. this device will give the flow velocity of blood in the blood vessels which is useful to the examiner, the equation of doppler as a mathematical model in the research is adopted the measured speed to clarify the amount of change in the frequency (shift in frequency). this speed was measured in five different blood vessels, large arteries (abdominal aorta and carotid artery in the neck) and large veins (the inferior vena cava across the abdomen and the external jugular vein in the neck) and capillaries in the hand and fingers. then using the measured velocities in these vessels the doppler frequency was calculated from this mathematical model using matlab program, was found that as velocity of the blood increases, so does the doppler frequency and vice versa. the greater the value of the doppler angle used in the device then the doppler frequency decreased and vice versa. as well as increasing the transmitted frequency giving an increase in the speed of blood flow and in the doppler frequency and vice versa. it was observed during the practical work that it was possible to get the speed of blood flow in different blood vessels, arteries and veins easily, but to less extent in the capillary vessels since in fact the value of the received frequency was very small. keywords: doppler frequency, blood flow, ultrasonic blood flow meter. 1. introduction the doppler effect provides a unique capability for ultrasound to measure blood flow [1]. the doppler principle states that the frequency of reflected ultrasound is altered by a moving target, such as red blood cells. the magnitude of this doppler shift relates to the velocity of the blood cells, whereas the polarity of the shift reflects the direction of blood flow toward (positive) or away (negative) from the transducer [2]. the doppler frequency shift is a change or shift in the frequency of the returning echoes compared to the frequency of the transmitted ultrasound waves which the basis for calculating blood flow velocities ,negative frequency shift (echoes reflected from blood flowing away from the transducer have lower frequencies compared to the transmitted ultrasound), positive frequency shift (echoes reflected from blood flowing toward the transducer have higher frequencies compared to the transmitted ultrasound) ,net frequency shift (echoes reflected from blood flowing perpendicular to the transducer exhibit no change in frequency compared to the transmitted ultrasound ) as shown in fig. (1) [3]. blood flow through the heart and great vessels has certain mailto:ghaidaa85@yahoo.com ghaidaa abdulrahman khalid al-khwarizmi engineering journal, vol. 8, no.4, pp 2639 (2012) 27 characteristics that can be measured using doppler instruments designed for medical use. for the purpose of understanding flow patterns in the heart, it is important to recognize the difference between laminar flow and turbulent (or disturbed) flow [4].laminar flow is the flow velocity in a straight vessel with uniform diameter; it represents the majority of normal blood flow. turbulent flow within an arterial or venous system, multiple factors exist that are capable of altering or disrupting laminar flow, as vessel tapering, curvature, bifurcations, and many other abnormal deformations as arterial stenosis and thrombus, cause turbulent flow [5]. the fact that makes the frequency of the doppler effect more than just an interesting curiosity is that it actually provides a method that is used to measure the direction and speed of moving red blood cells. doppler methods extend the use of cardiac ultrasound into the evaluation of normal and abnormal flow states and provide quantitative data that are essential in the clinical decision making process concerning patients with heart disease [4]. carotid artery disease is also called carotid artery stenosis. the term refers to the narrowing of the carotid arteries. this narrowing is usually caused by the buildup of fatty substances and cholesterol deposits, called plaque. carotid artery occlusion refers to complete blockage of the artery. when the carotid arteries are obstructed, there will be an increased risk for a stroke [6]. fig. 1. doppler frequency shift [3]. 2. mathematical model of doppler frequency the shift in frequency is related to the contraction or expansion of wavelengths ahead of or behind the sound-emitting moving object shown in fig. (2). the wavelength of the sound, is the speed of sound propagation, c, divided by the frequency of the sound. as sound speed is defined in units of length divided by time and frequency is the number of cycles per unit time, wavelength is expressed in units of length. the velocity of the moving object, v, is also in units of length divided by time. as the sound is emitted from the moving object, the wavelengths observed at points on either side of the object are lengthened ( l) or shortened ( s). because wavelength is inversely proportional to frequency, the observer will detect a frequency different from that emitted by the object when it has zero velocity [7]: …(1) …(2) in equations (1) and (2), ƒ is the frequency of the sound emitted by the object and would be detected by the observer if the object were at rest, (±δƒ) represents a doppler effect–induced frequency shift. the sign depends on the direction in which the object is traveling with respect to the observer. in the case of ultrasound scattering back from moving objects (e.g., red blood cells) in the body, the derivation of the doppler equation may follow that of wells because ultrasound is used in a transmit-echo approach. there is a doppler effect with the sound arriving at the scattering object and a doppler effect as the sound is reflected from that object back toward the ultrasound transducer. in us, the round trip time for sound is related to the depth and the speed of sound in tissue. as seen in equations (1) and (2), an inverse relationship exists between frequency and the wavelength of the sound transmitted to the red blood cells. the sound speed is constant (c tissue = 1,540 m/sec) in this relationship. the frequency of the sound incident on the red blood cell is changed because the relative velocity of the red blood cell is added to the sound propagation speed. the variables can be rearranged in the form of the transmitted frequency, ƒo, and an object velocity term [7]: …(3) ghaidaa abdulrahman khalid al-khwarizmi engineering journal, vol. 8, no.4, pp 2639 (2012) 28 …(4) the sound is then reflected back toward the transducer in the echo from the red blood cell. the frequency of sound arriving back at the transducer is shifted again in proportion to the red blood cell velocity [7]: …(5) the equation for the frequency returning back to the transducer, f , can be rewritten once again with respect to the original frequency, ƒo, and the wavelengths of the incoming and outgoing waves. these relationships are now substituted into the following equation to put everything in terms of the red blood cell velocity, vrbc, the original frequency, ƒo, and the speed of sound propagation, c [7]: …(6) …(7) since …(8) the relative velocity (to be indicated as vr) between the red blood cell and the transducer is dependent on the angle of a straight line (the line down which the sound is traveling) and the red blood cell and the direction of the red blood cell motion as shown in fig.(3). in other words, if the red blood cell were traveling directly toward the transducer (or directly away), the relative velocity would be at a maximum (or the negative maximum). when cosine 0° =1, vr =v rbc at 0°. when cosine 180°=1, vr = vrbc at 180°. since cosine 90° =0, vr = 0 at 90°. this relationship can also be written as vr = vrbc * cosө , where the angle is indicated in fig (2). plugging this relationship into equation 8, the doppler equation can be obtained [7]: …(9) …(10) ƒd = doppler shift frequency that is affected by the density of the particles (red blood cell) in the blood vessel. vrbc = the velocity of blood in the vessel. ƒo = transmitted frequency. c = the velocity of the sound in the blood. θ = doppler angle. fig. 2. as an object emitting sound moves at a velocity v, the wavelength of the sound in the forward direction is compressed ( s) and the wavelength of the sound in the receding direction is elongated ( l), c = sound speed [7]. ghaidaa abdulrahman khalid al-khwarizmi engineering journal, vol. 8, no.4, pp 2639 (2012) 29 fig. 3. the velocity of red blood cells relative to the position and angle of the transducer depends on the angle (ө) between the direction of sound propagation and the motion of the particle [7]. 3. experimental work this work was done on a subject that has normal blood vessels history whose age is 30 years old, and on an abnormal subject that have a problem of carotid stenosis; his age was 38 years old. the doppler device was applied to each one of them in yarmuk teaching hospital. this device which has a linear probe of 4 -12 mhz frequency was applied to the subject body after putting ultrasonic gel on his skin, in order to make the movement of the probe more easier and the transmission of the ultrasonic wave better, the blood flow velocity was measured by placing the probe (a highly loaded lead zirconate titanate ultrasonic transducer is usually used for this purpose ) of the ultrasonic doppler device on the large arteries (abdominal aorta and carotid artery in the neck), large veins (the inferior vena cava across the abdomen and the external jugular vein in the neck) , and the capillaries of the hand and fingers. at each type of these five different blood vessels, the doppler shift frequency was calculated by making the ultrasonic device using a band of transmitted frequencies toward each type of vessels and using different probes angles for each frequency transmitted. after getting the velocity of the blood flow for each vessel of the two subject from the device, the doppler shift frequency can be calculated from equation (10) by using mathlab program, in order to prove that the doppler frequency is dependent on: 1. blood velocity: as velocity increases, the shifted doppler frequency increases also as shown in table (1) [8]. 2. ultrasound frequency: higher ultrasound frequencies give less depth of penetration, and lower ultrasound frequencies have better penetration. this is due to the fact that the wavelength is inversely proportional to frequency, the frequency transmitted ranges between 2mhz and 12mhz, and table (2) shows the best range of frequencies used in vascular region [9]. 3. doppler angle: the doppler frequency increases as the doppler ultrasound beam becomes more aligned to the flow direction (the angle θ between the beam and the direction of flow becomes smaller) this is of the most importance in the use of doppler ultrasound, as explained by fig. (4) [10]. 4. direction of blood flow: if the flow of blood has the same direction as the ultrasonic beam, then it is considered that the blood is flowing away from the transducer. in this case, the doppler shift frequency is lower than zero, and when the blood flow is opposite to the direction of the ultrasonic beam, it is greater than zero [11]. 5. ultrasound probe: there are different types of transducers which are used with the ultrasound system; these are curved, phased, and linear. the curved and phased are not used in vascular application, the linear probe is vascular probe and used for measuring blood flow in the vessels. table 1, normal blood flow velocities in different types of blood vessels [8]. blood vessel diameter (cm) velocity (cm\sec) capillary 0.00050.001 0.005-0.1 large arteries 2-60 20-25 large veins 0.5-1 15-20 table 2, the transmitted frequencies that are used to measure blood flow according to depth [9]. application and depth 7 mhz-12 mhz 4mhz-7mhz vascular (03cm depth) best better vascular (38cm depth) better best ghaidaa abdulrahman khalid al-khwarizmi engineering journal, vol. 8, no.4, pp 2639 (2012) 30 fig. 4. effect of the doppler angle in the sonogram. (a) higher-frequency doppler signal is obtained if the beam is aligned more to the direction of flow. in the diagram, beam (a) is more aligned than (b) and produces higher-frequency doppler signals. the beam/flow angle at (c) is almost 90° and there is a very poor doppler signal. the flow at (d) is away from the beam and there is a negative signal [11]. 4. results and discussion 4.1. doppler effect with normal subject since the doppler shift frequency represent, a change or shift in the frequency of the returning echoes compared to the frequency of the transmitted ultrasound waves [fd= fr-ft] as shown in tables [3,4,5,6&7], the doppler shift frequency have a higher magnitudes (greater than zeroes) and a positive polarity [2,11], which means that the blood flow in these vessels is opposite to the direction of an ultrasonic beam emitted from the transducer, and the echoes reflected back from blood cells flowing towards the ultrasonic transducer giving values greater than zero and positive polarity [3]. table (3) represents values of doppler shift frequency in carotid artery for normal subject. as an example, if the transmitted frequency is 7 mhz, and doppler angle is 30o ,the measured velocity from the device was 15.45 cm/sec, then by using equation (10) the doppler shifted frequency will be 1.2 khz , which is greater than zero; blood flow is opposite to the direction of an ultrasonic beam emitted from the transducer, and the echoes that reflected back from blood cells flowing towards the transducer. at the same transmitted frequency (7 mhz) ,with doppler angle 45o ,60o, the measured velocity will be 19.07,19.2 cm/sec respectively, which means that the velocity of blood flow increases as doppler angle increases at the same transmitted frequency until it reaches 37.1 cm /sec at 75 o ,while the shifted doppler frequency will be at 45 o 1.208khz while at 60 o,75 o it will be 0.86,0.85khz, respectively. these different changes in the values of the shifted doppler frequency are at the same transmitted frequency because the movement of the blood cells in the vessels is in circular groups with laminar flow, so the transducer will emit the same frequency to each group of cell but receive different echoes magnitude from the cells according to their distance from the transducer, so there will be different doppler shift frequency as shown in tables (3, 4, 5, 6, &7). it is important to understand the doppler shift frequency since some of the ultrasonic doppler device gives only the doppler shift frequency then by using doppler mathematical model in equation (10), the blood flow velocity can be determined. from the graphical representations of the normal subject found in figures (5), the velocity of blood flowing in the carotid artery was found. the transmitted frequencies wear 7,8,10,&12mhz which has been selected to measure blood flow according to the depth of this vessel as shown in table(2) [9]. at each one of these transmitted frequencies, there are three different reigns of angles. this figure shows nearly linear relationship between velocity and doppler angle. the first liner region is between 30° to 45°, where the velocity is lower than normal physiological reference which is 20-25 cm/sec in large artery. at angles between 45° to 60°, there is another linear region that that differs from the first region where the velocity is almost the same as that of the normal physiological reference 20-25 cm/sec. the third linear region at angles between 60-75° the velocity is much higher than normal physiological references. so figure(5) shows that in order to get the most accurate measure for velocity of blood flow in carotid artery, so during the investigation of the subject the doppler ultrasound system's probe needs a modification for the doppler angle to be between 45°and 60° between the probe of the device and the vessel direction. from the graphical representations of the normal subject found in figure (6) the velocity of blood flowing in aorta, was found. the transmitted frequencies 4,5,6,&7mhz which wear selected to measure blood flow according to the depth of this vessel as shown in table(2) [9]. each one of these transmitted frequencies, there are three different reign of angles. this figure shows ghaidaa abdulrahman khalid al-khwarizmi engineering journal, vol. 8, no.4, pp 2639 (2012) 31 nearly linear relationship between velocity and doppler angle. the first liner region is between 30° to 45°, where the velocity is lower than normal physiological reference which is 20-25 cm/sec in large artery. at angles between 45° to 60,° there is another linear region that differs from the first region where the velocity is almost the same as that of the normal physiological reference 20-25 cm/sec. the third linear region is at angles between 60-75°. the velocity is much higher than normal physiological references. so figure(6) shows that during the investigation of the subject the doppler ultrasound system's probe must be aligned at an angle between 45°and 60° between the probe of the device and the vessel direction to get the accurate velocity measurement and diagnosis. from the graphical representations of the normal subject found in figure (7) the velocity of blood flowing in the large vein (inferior vena cava) was found. the transmitted frequencies ware 4,5,6,&7mhz which were selected to measure blood flow according to the depth of this vessel as shown in table(2) [9]. at each one of these transmitted frequencies, there are three different reign of angles in this figure shows nearly linear relationship between velocity and doppler angle. the first liner region is between 30° to 45°, where the velocity is lower than normal physiological reference which is 15-20 cm/sec in large artery; at angles between 45° to 60° there is another linear region differ from the first region where the velocity is almost the same as that of the normal physiological reference 1520 cm/sec. the third linear region is at angles between 60-75° .the velocity is much higher than 15-20 cm/sec. so figure(7) shows that during the investigation of the subject the doppler ultrasound system's probe must be aligned at an angle between 45°and 60° between the probe of the device and the vessel direction to get the accurate velocity measurement and diagnosis. from the graphical representations of the normal subject that found in figure (8) the velocity of blood flowing in the external jugular vena cava was found. that the transmitted frequencies 7,8,10,&12mhz which were selected to measure blood flow according to the depth of this vessel as shown in table(2) [9]. at each one of these transmitted frequencies, there are three different reign of angles. this figure shows nearly linear relationship between velocity and doppler angle ,the first liner region is between 30° to 45°, where the velocity is lower than normal physiological reference which is 15-20 cm/sec in large artery. at angles between 45° to 60° there is another linear region that differs from the first region where the velocity is almost the same as that of the normal physiological reference 15-20 cm/sec. the third linear region at angles between 60-75° the velocity is much higher than normal physiological references. so figure (8) shows that the doppler angle of the probe must be aligned to be between 45°and 60° with the vessel direction. from the graphical representations of the normal subject found in figure (9) the velocity of blood flowing in the capillary was found. the transmitted frequencies are 7,8,10,&12mhz which were selected to measure blood flow according to the depth of this vessel as shown in table(2) [9]. at each one of these transmitted frequencies, there are three different reign of angles in this figure shows nearly linear relationship between velocity and doppler angle. the first liner region is between 30° to 45°, where the velocity is lower than normal physiological reference which is 1520 cm/sec in large artery; at angles between 45° to 60° there is another linear region differ from the first region where the velocity is almost the same as that of the normal physiological reference which is 15-20 cm/sec. the third linear region at angles between 60-75° the velocity is much higher than normal physiological references. so figure (9) shows that the doppler angle of the probe must be aligned to be between 45°and 60° with the vessel direction. table 3, values of doppler shift frequency in carotid artery for normal subject. transmitted frequency (ft mhz) doppler angle(ө) the measured velocity (v cm/sec) doppler shifted frequency (calculated) (fd khz) 7 30 15.45 1.20 7 45 19.07 1.208 7 60 19.20 0.86 7 75 37.1 0.85 8 30 9.36 0.83 8 45 15.20 1.10 8 60 20.00 1.02 8 75 32.43 0.85 10 30 14.18 1.57 10 45 16.27 1.47 10 60 19.89 1.27 10 75 37.03 1.22 12 30 15.10 2.01 12 45 16.20 1.76 12 60 20.09 1.54 12 75 37.80 1.50 ghaidaa abdulrahman khalid al-khwarizmi engineering journal, vol. 8, no.4, pp 2639 (2012) 32 table 4, values of doppler shift frequency in aorta for normal subject. transmitted frequency (ft mhz) doppler angle(ө) the measured velocity (v cm/sec) doppler shifted frequency (calculated) (fd khz) 7 30 11.7 0.90 7 45 17.07 1.08 7 60 23.60 1.05 7 75 36.10 0.83 6 30 12.20 0.81 6 45 19.07 1.03 6 60 24.68 0.94 6 75 36.17 0.71 5 30 14.70 0.81 5 45 21.25 0.96 5 60 25.50 0.81 5 75 38.87 0.64 4 30 15.18 0.67 4 45 20.27 0.73 4 60 25.30 0.64 4 75 37.0 0.48 table 6, values of doppler shift frequency in inferior vena ceva for normal subject. transmitted frequency (ft mhz) doppler angle(ө) the measured velocity (v cm/sec) doppler shifted frequency (calculated) (fd khz) 7 30 10.47 0.81 7 45 12.90 0.81 7 60 16.90 0.75 7 75 27.60 0.70 6 30 11.82 0.77 6 45 13.50 0.73 6 60 17.11 0.65 6 75 27.79 0.59 5 30 11.80 0.65 5 45 13.90 0.62 5 60 18.68 0.59 5 75 28.95 0.47 4 30 11.80 0.49 4 45 13.97 0.50 4 60 18.02 0.46 4 75 28 0.37 table 7, values of doppler shift frequency in capillary for normal subject. transmitted frequency (ft mhz) doppler angle(ө) the measured velocity (v cm/sec) doppler shifted frequency (calculated) (fd khz) 7 30 0.033 0.0045 7 45 0.039 0.0043 7 60 0.049 0.0038 7 75 0.085 0.0034 8 30 0.037 0.0042 8 45 0.040 0.0037 8 60 0.050 0.0032 8 75 0.087 0.0029 10 30 0.042 0.0038 10 45 0.045 0.0033 10 60 0.048 0.0025 10 75 0.183 0.0022 12 30 0.038 0.0030 12 45 0.037 0.0024 12 60 0.042 0.0019 12 75 0.056 0.0013 table 5, values of doppler shift frequency in external jugular vena ceva for normal subject. transmitted frequency (ft mhz) doppler angle(ө) the measured velocity (v cm/sec) doppler shifted frequency (calculated) (fd khz) 7 30 9.77 0.74 7 45 11.50 0.72 7 60 14.93 0.64 7 75 27.64 0.63 8 30 10.08 0.89 8 45 11.47 0.83 8 60 15.28 0.78 8 75 26.60 0.70 10 30 11.25 1.24 10 45 12.68 1.14 10 60 14.82 0.95 10 75 26.60 0.87 12 30 11.67 1.55 12 45 13.08 1.51 12 60 15.12 1.16 12 75 27.60 1.07 ghaidaa abdulrahman khalid al-khwarizmi engineering journal, vol. 8, no.4, pp 2639 (2012) 33 fig. 5. the velocity of the blood flow versus the doppler angle in carotid artery for different frequencies [7, 8, 10, 12 mhz] for normal subject. fig. 6. the velocity of the blood flow versus the doppler angle in aorta for different frequencies [4, 6, 5,7mhz] for normal subject. fig. 7. the velocity of the blood flow versus the doppler angle in large vein (inferior vena ceva) for different frequencies [4, 5, 6,7mhz] for normal subject. fig. 8. the velocity of the blood flow versus the doppler angle in external jugular vein for different frequencies [7, 8, 10, 12 mhz] for normal subject. ghaidaa abdulrahman khalid al-khwarizmi engineering journal, vol. 8, no.4, pp 2639 (2012) 34 fig. 9. the velocity of the blood flow versus the doppler angle in capillary for different frequencies [7, 8, 10, 12mhz] for normal subject. 4.2. doppler effect with abnormal subject the doppler shift frequency for abnormal subject shown in tables (9,10,11,&12) is the same as that found with normal person except for that found in table (8) which indicates there is a stenosis in the carotid artery where the region at the doppler angle between 45-60o the velocity decreased gradually until it reached sever stenosis at 60 degree where blood flowing was obstructed by narrowing of the artery which is usually caused by the buildup of fatty substances and cholesterol deposits, called plaque. so as the velocity decreased, the doppler shift frequency decreased also. for example, at 7mhz (45owas 1.291& 60o was 0.736), at 8mhz (45owas 1.41 khz& 60o was 1.02 khz), at 10mhz (45owas 2.4 khz & 60o was 0.98 khz), at12 mhz (45owas 2.19 khz & 60o was 1.3 khz). this high decrease in the doppler shift magnitudes is consider as an indication for the presence of turbulent flow, where the presence of stenosis increases the value of echoes received by the transducer, so the shift frequency will be reduced. from the graphical representations of the abnormal subject (undergoes stenosis in the carotid artery) that found in figure (10), the velocity of blood flowing in the carotid artery was found. the transmitted frequencies are 7,8,10,&12mhz which has been selected to measure blood flow according to the depth of this vessel as shown in table(2) [9]. at each one of these transmitted frequencies, there are three different reign of angles. this figure shows nearly linear relationship between velocity and doppler angle, the first liner region is between 30° to 45°, where the velocity is almost the same as that of the normal physiological reference which is 20-25 cm/sec and there is no appearance or indication for any abnormal flow. at angles between 45° to 60°, there is another linear region differed from the first region where the velocity at 7 mhz (45o was 20.09 cm/sec,60o ,was 16.2 cm/sec) ,at 8mhz (45o was 19.20 cm/sec,60o was 20 cm/sec),at 10mhz (45o was 20 cm/sec,60o was 15.2 cm/sec), at 12mhz (45o was 19.89 cm/sec,60o was 16.7cm/sec).obviously in this region (45 o -60o ) when compared with normal person, at each transmitted frequency, the velocity of the blood decreased gradually until it reached lower value than that of the normal physiological references that were 20-25 cm/sec since the diameter of the artery decreased gradually making blood flow turbulent. so this is an indication for the appearance of problem of stenosis, the third linear region at angles between 60-75°. the velocity is very much higher than normal physiological references. so in order to get the most accurate measurement for velocity of blood flow in carotid artery and to get best diagnosis for the stenosis artery, the doppler ultrasound system's probe needs a modification for the doppler angle to be between 45°and 60° between the probe of the device and the vessel direction. all the graphical representations found in figures (11,12,13,&14) when compared with normal subject have the same characteristic found in the normal subject ,which means that there is no disease in these vessels. ghaidaa abdulrahman khalid al-khwarizmi engineering journal, vol. 8, no.4, pp 2639 (2012) 35 table 8, values of doppler shift frequency in carotid artery for abnormal subject. table 9, values of doppler shift frequency in aorta for normal subject. table 10, values of doppler shift frequency in external jugular vena ceva for abnormal subject. table 11, values of doppler shift frequency in inferior vena cava for abnormal subject. transmitted frequency (ft mhz) doppler angle(ө) the measured velocity (v cm/sec) doppler shifted frequency (calculated) (fd khz) 7 30 10.47 0.81 7 45 12.90 0.81 7 60 16.90 0.75 7 75 27.60 0.70 6 30 11.82 0.77 6 45 13.50 0.73 6 60 17.11 0.65 6 75 27.79 0.59 5 30 11.80 0.65 5 45 13.90 0.62 5 60 18.68 0.59 5 75 28.95 0.47 4 30 11.80 0.49 4 45 13.97 0.50 4 60 18.02 0.46 4 75 28 0.37 transmitted frequency (ft mhz) doppler angle(ө) the measured velocity (v cm/sec) doppler shifted frequency (calculated) (fd khz) 7 30 9.77 0.74 7 45 11.50 0.72 7 60 14.93 0.64 7 75 27.64 0.63 8 30 10.08 0.89 8 45 11.47 0.83 8 60 15.28 0.78 8 75 26.60 0.70 10 30 11.25 1.24 10 45 12.68 1.14 10 60 14.82 0.95 10 75 26.60 0.87 12 30 11.67 1.55 12 45 13.08 1.51 12 60 15.12 1.16 12 75 27.60 1.07 transmitted frequency (ft mhz) doppler angle(ө) the measured velocity (v cm/sec) doppler shifted frequency (calculated) (fd khz) 7 30 15.45 1.20 7 45 20.09 1.291 7 60 16.20 0.736 7 75 37.1 0.85 8 30 9.36 0.83 8 45 19.20 1.41 8 60 37.00 1.02 8 75 32.43 0.85 10 30 14.18 1.57 10 45 20 2.4 10 60 15.2 0.98 10 75 37.03 1.22 12 30 15.10 2.01 12 45 19.89 2.19 12 60 16.7 1.3 12 75 37.80 1.50 transmitted frequency (ft mhz) doppler angle(ө) the measured velocity (v cm/sec) doppler shifted frequency (calculated) (fd khz) 7 30 11.7 0.90 7 45 17.07 1.08 7 60 23.60 1.05 7 75 36.10 0.83 6 30 12.20 0.81 6 45 19.07 1.03 6 60 24.68 0.94 6 75 36.17 0.71 5 30 14.70 0.81 5 45 21.25 0.96 5 60 25.50 0.81 5 75 38.87 0.64 4 30 15.18 0.67 4 45 20.27 0.73 4 60 25.30 0.64 4 75 37.0 0.48 ghaidaa abdulrahman khalid al-khwarizmi engineering journal, vol. 8, no.4, pp 2639 (2012) 36 table 12, values of doppler shift frequency in capillary for abnormal subject. transmitted frequency (ft mhz) doppler angle(ө) the measured velocity (v cm/sec) doppler shifted frequency (calculated) (fd khz) 7 30 0.033 0.0045 7 45 0.039 0.0043 7 60 0.049 0.0038 7 75 0.085 0.0034 8 30 0.037 0.0042 8 45 0.040 0.0037 8 60 0.050 0.0032 8 75 0.087 0.0029 10 30 0.042 0.0038 10 45 0.045 0.0033 10 60 0.048 0.0025 10 75 0.183 0.0022 12 30 0.038 0.0030 12 45 0.037 0.0024 12 60 0.042 0.0019 12 75 0.056 0.0013 fig. 10. the velocity of the blood flow versus the doppler angle in carotid artery for different frequencies [7, 8, 10, 12 mhz] for abnormal subject. fig. 11. the velocity of the blood flow versus the doppler angle in aorta for different frequencies [4, 6, 5,7mhz] for abnormal subject subject. fig. 12. the velocity of the blood flow versus the doppler angle in large vein (inferior vena cevan for different frequencies [4, 5, 6,7mhz] for abnormal subject. ghaidaa abdulrahman khalid al-khwarizmi engineering journal, vol. 8, no.4, pp 2639 (2012) 37 fig. 13. the velocity of the blood flow versus the doppler angle in external jugular vein for different frequencies [7, 8, 10, 12 mhz] for abnormal subject. fig. 14. the velocity of the blood flow versus the doppler angle in capillary for different frequencies [7, 8, 10, 12mhz] for abnormal subject. 5. conclusions 1. the size of the doppler signal is dependent on blood velocity, as velocity increases, so does the doppler frequency. 2. in the doppler ultrasound, the penetration depth in the human body is inversely proportionate with the transmitted frequencies as explained in table (2).the relationship between shifted doppler frequencies and doppler angles is nearly linear for each group of doppler angles. as the doppler angle increases the shifted doppler frequency decreases and vice versa. 3. transmitted frequencies have great effect on shifted doppler frequencies and on measured velocities. as transmitted frequency increases the shifted doppler frequency and measured velocities increase and vice versa. 4. the doppler ultrasound system's probe needs a modification for the angle to be between 45°and 60° between the probe and the vessel direction to give the most accurate measure. 5. the doppler ultrasound can measure the blood flow in all types of blood vessels, arteries, veins, but to less extent the capillaries as the scattered frequency from them is very small and inaudible. 6. doppler methods can be used for the evaluation of normal and abnormal flow states and provides quantitative data that are essential in the clinical decision .making process concerning patients with heart disease. 6. references [1] evans and mcdicken, 2000, jensen, 1996. [2] miguel a. quiñones, md, chair, catherine m. otto, md, marcus stoddard ,february 2002,journal of the american society of echocardiography,volume 15 number 2. [3] bernard e. bulwer ,jose m. river ,echocardiography pocket guide: the transthoracic examination,chapter4,2011. [4] joseph a. kisslo, md, david b. adams, rdcs,principels of doppler echocardiography and the doppler examination. [5] internationalhemodynamicsociety,“what ishemodynamics”,http://www.hemodynamics ociety.org/hemodyn.html [6] www.webmd.com ,carotid artery disease: causes, symptoms, tests, and treatment, ©2005-2012. [7] evan j. boote, phd., doppler us techniques: concepts of blood flow detection and flow dynamics , from the department of radiology, university of missouriseptemberoctober 2003, volume 23 , number 5. [8] gill r.w., measurement of blood flow by ultrasound. ultrasound med bio, 1985; 7:62542. http://www.hemodynamics http://www.webmd.com ghaidaa abdulrahman khalid al-khwarizmi engineering journal, vol. 8, no.4, pp 2639 (2012) 38 [9] royal philips elecronics, (transducer guide) hdi broad band andautomatic 3d transducers for all your patient, atl hdi 4000 ultrasound system; 2002. [10] terms-doppler, doppler ultrasound. available from http//www.doppler ultrasound/termsdoppler. [11] nicolaides k., rizzo g. , hecker k., ximenes r., doppler in obstetrics, 2002, isuog educational series, centrus. 2012)( 2639، صفحة 4، العدد8مجلة الخوارزمي الھندسیة المجلد غیداء عبد الرحمن خالد 39 ظاھرة دوبلر على سرعة تدفق الدم مدى تأثیر غیداء عبدالرحمن خالد بغداد-الكلیة التقنیة الكھربائیة و االالكترونیة/ قسم ھندسة تقانة االجھزة الطبیة ghaidaa85@yahoo.com: البرید االلكتروني الخالصة كطریقة یتم من خاللھا قیاس اتجاه وسرعة جریان خالیا الدم في االوعیة الدمویة، حیث أن ھذا التردد ) تردد دوبلر(راسة ظاھرة دوبلرھذا البحث یعتمد د دمویة في ألوعیة التم االعتماد علیة طبیا في قیاس سرعة جریان الدم، اذ ان جریان الدم یعتبر مفھوما مھما من مفاھیم الطب فھویمثل وظیفة وكفأة القلب وا اذ ان ھذة السرعة تتغیر كثیرا في حاالت الجسم لذلك فأن اي خلل في ھذه الوظیفة سیظھر كتغییر في سرعة جریان الدم عن القیمة الطبیعیة المفترضة، االرسال واالستالم وتأثیر تغییر والجل التعرف على تأثیرتغییر تردد دوبلر على سرعة جریان الدم وعالقة ھذا التردد مع زاویا المرض اواالعتالل القلبي، سة تم استخدام جھاز الدوبلر فوق السمعي كونة الجھاز األكثر كفأءة واألسھل استعماال كتطبیق عملي تردد الموجة فوق الصوتیة المرسلة على السرع المقا شریان في مستشفى الیرموك التعلیمي على شخصین أحدھما طبیعي یمتلك تاریخ طبي طبیعي في االوعیة الدمویة، واألخر غیر طبیعي یمتلك ضییق في ال یدنا بسرعة جریان الدم في األوعیة الدمویة وھي التي تھم الفاحص ، لذلك قمنا بأعتماد معادلة دوبلر كمودیل ریاضي في السباتي، حیث یقوم ھذا الجھاز بتزو ،علما ان ھذة السرعة تم قیاسھا في خمسة أوعیة ) (shift in frequencyبحثنا لألستفادة من ھذه السرعة المقاسة في توضیح مقدار التغییر في التردد الورید األجوف السفلي في جمیع أنحاء البطن والورید (واألوردة الكبیرة ) االبھر البطني والشریان السباتي في العنق(لفة، الشرایین الكبیرة دمویة مخت دوبلر من النموذج والشعیرات الدمویة في الید واألصابع، ثم باستخدام السرع المقاسة في ھذه األوعیة المختلفة تم حساب تردد) الوداجي الخارجي في الرقبة حیث وجد انھ كلما زادت سرعة جریان الدم حصل ازدیاد في قیمة تردد دوبلر والعكس بالعكس، وكلما زادت ،matlab الریاضي باستخدام برنامج كلما زادت قیمتھا حصل قیمة زاویة دوبلر المستخدمة في الجھاز حصل نقصان في تردد دوبلر والعكس بالعكس، وكذلك الترددات المستخدمة في االرسال ي االوعیة ازدیاد في سرعة جریان الدم وفي تردد دوبلر والعكس بالعكس، ومن خالل الدراسة تم مالحظة انھ من الممكن الحصول على سرعة جریان الدم ف .ذات قیمة صغیرة جداالدمویة المختلفة الشرایین واألوردة بسھولة ولكن بمدى قلیل في االوعیة الشعریة كون الترددات المستلمة mailto:ghaidaa85@yahoo.com dr nabil hassan-1 dr.nabil hassan hadi/al-khwarizmi engineering journal ,vol.1, no. 2,pp 41-51 (2005) 41 al-khwarizmi engineering journal al-khwarizmi engineering journal, vol.1, no.2,pp 41-51, (2005) fuzzy control of mobile robot in slippery environment dr.nabil hassan hadi mechanical engineering department/ college of engineering/ university of baghdad (received 20 april 2005; accepted 2 october 2005) abstract: the problem of independent motion control of mobile robot (мr) in conditions when unforeseen changes of conditions of interaction of wheels with a surface are considered. an example of such changes can be sudden entrance мr a slippery surface. the deployment of an autonomous unmanned ground vehicle for field applications provides the means by which the risk to personnel can be minimized and operational capabilities improved. in rough terrain, it is critical for mobile robots to maintain good wheel traction. wheel slip could cause the rover to lose control and become trapped. this paper describes the application of fuzzy control to a feedback system within slippery environment. the study is conducted on an example of мr with two driving wheels. keywords: mobile robot, fuzzy control, wheel-ground contact modeling, dynamic model 1. introduction the classical control theory which relies on the mathematical model of the underlying system has been successfully applied to the control of a large variety of simple, non-linear processes. however, it has not been as widely used with complicated, nonlinear, time varying systems or with processes suffering from noisy measurements. the main idea of fuzzy control is to build a model of an expert operator who is capable of controlling the plant without thinking in terms of a mathematical model. the problem of independent motion control of mobile robot (мr) in conditions when unforeseen changes of conditions of interaction of wheels with a surface are considered. an example of such changes can be sudden entrance мr a slippery surface. mobile robots are increasingly being developed for high-risk missions in rough terrain environments. one successful example is the nasa/jpl sojourner martian rover[1]. other examples of rough terrain applications for robotics systems can be found in the forestry and mining industgyries, and in hazardous material handling applications, such as the chernobyl disaster site cleanup[2]. in fuzzy logic (fl) control [3,4], pdtype and pi-type fl controllers are the bestknown counterparts of the pid controller. they are used to achieve better performance with nonlinear processes. good experiences have been obtained especially with the pdtype fl controllers in servo applications [5,6]. future planetary missions will require mobile robots to perform difficult tasks in more challenging terrain. in addition to the importance of the perception system, mainly visual guidance, motion planning is a key function in preparing locomotion tasks and enhancing the capability of the autonomous vehicle to move safely toward its target position. the response of the vehicle when evolving in an unstructured or partially structured outdoor environment depends on the combination of several geometric and physical criteria. these include the mechanical structure of the vehicle, the geometric and physical dr.nabil hassan hadi/al-khwarizmi engineering journal ,vol.1, no. 2,pp 41-51 (2005) 42 features of the terrain, wheel ground interactions, characteristics of the received commands and the applied motion control law[7]. in most cases, base control which is intended for normal modes of interaction of wheels with a surface, in such situation is not capable to keep мr on a program trajectory. in work [8] the structure of a control system was proved and the base logical algorithms allowing effectively to operate by moving the мr on a program trajectory under enough good conditions of coupling of wheels with a surface. in work [9] base algorithm was added with the logic blocks intended for correction of control at deterioration of conditions of coupling of wheels with a surface. it was shown, that even under very bad conditions of coupling (for example, the movement of мr on a slippery surface), correction of control allows to keep мr on a program trajectory. two circumstances are important: a choice of adjusting control and diagnostics of occurrence slippery. today, fuzzy logic has been widely used in automotive control applications and has transformed many commercial product markets in japan and germany. many experts predict that fuzzy technology is on its way to becoming a multibillion-dollar industry. the main idea behind fuzzy control is to model an expert operator who is able to control the process, instead of using a mathematical formalization of the process as in modern control theory. although there are many practical successes, fuzzy control has not been viewed as a rigorous science due to a lack of formal synthesis techniques. fuzzy control should be useful when a workable mathematical model for a plant is very difficult or impossible to derive or the mathematical model is complex and computing it in real time would require expensive processors. this paper describes the application of fuzzy control to a feedback system within slippery environment where the basic attention is given to a problem of diagnostics. study is conducted on example of мr with two driving wheels. 2. wheel-ground contact model numerous approaches to wheelground modeling are documented in the literature. simple one is adopted here to describe tire forces in the vertical (i.e., normal to the road surface) and longitudinal (in the tire plane, tangent to the road surface) directions. in development of the model of wheel we shall take into account two main effects[9]: effect of pseudo-sliding, type creep and withdrawal which are coherent with deformation of periphery of a wheel [10], and also the effect of full slip condition type and the lateral drift for which deformation of periphery of a wheel is the minor factor. in both cases there is an infringement of the connections describing ideal contact of a wheel with a surface. however, at pseudosliding a deviation of parameters of movement in comparison with infringement as a case are considered small, and at full slipping unlimited deviations basically are possible. the control problems of rolling wheels model of мr for cases of pseudosliding were considered by many authors [11,12,13] usually pseudo-sliding is considered in the assumption of independence creep and withdrawal [14]. the model of a wheel at full slipping when deformation of periphery of a wheel can be neglected, is presented in work [9]. in [15] the wheel is considered as a thin hard disk, and interaction in a point of contact of a wheel with a surface is described by model of friction with a falling site of the characteristic, such as creep-effect. thus longitudinal and wheels cross slipping interference is taken into account. in work [9] standard coordination was used for the model of a wheel at pseudo-sliding and model for a wheel at full slipping conditions. this problem is offered to be solved within the framework of rolling wheel model algorithmic, providing a continuity of change of the force characteristic in a point of contact of the wheel with a surface. the friction force r (with components r1 in 1i direction and r2 in 2i direction, figure 1) parallel to the road surface is[9] dr.nabil hassan hadi/al-khwarizmi engineering journal ,vol.1, no. 2,pp 41-51 (2005) 43 2211 irirr += ( ) ( )         −−=            > < −−= 1 2 2 2 2 111 11 1 1 1 ,min , , ,min v v c v v vnr rvvv rvrv c v v vnr s s s ws wws s s s µ ω ωω µ (1) 2211 ivivv ss +=s ws rvv ω+= 11 , 22 svv = where n normal reaction; ( )svµ factor of a sliding friction with the account of creep effect; −sv a vector of speed of sliding of a wheel in a point of contact; 1v , 2v are the longitudinal and cross speeds of the centre of a wheel; ω angular speed of a wheel; wr radius of a wheel; 1c and 2c factors of resistance creep and to withdrawal. algorithmic model ( 1 ) expresses the dependence of horizontal reaction on three independent parameters of movement of a wheel ( )21 ,, vvrr ω= . integration of eq.(1) is carried out with suitable time step, providing a continuity of transition from the description of pseudo-sliding to the description full slipping. 3. dynamics model of мr the dynamic model is obtained from the kinematics model by adding dynamics properties to the robot model such as mass, inertia moments, friction as well as by extending the virtual environment with gravitation field and ground contact forces. kinematic and drive motor circuits of the мr are shown in figure 1. τ ωr r, ϕ rr 1 vr 1 rr 2 vr 2 ω с v1 v2 v y x i2 i1 rl 1 rl 2 vl 2 a τ ωl l, vl 1 l fig.1 kinematic and drive motor circuits of мr dr.nabil hassan hadi/al-khwarizmi engineering journal ,vol.1, no. 2,pp 41-51 (2005) 44 the dynamics model of мr with the use of slipping model algorithmic (1) is[9] ( ) ( ) lll w ll l w rrr w rr r w lrlr lr lr hdurrj hdurrj rrarrlj vvyvmrrvm vvxvmrrvm ωττω ωττω ϕ ϕϕ ϕϕ −=−= −=−= ω=++−=ω −=ω−+= +=ω++= • • •• •• •• , , , cossin, sincos, 1 1 2211 211222 212111 (2) ( )( ) ( )( )rrrrrrr lllllll vvririrr vvririrr 21211 212211 ,, ,, ω ω =+= =+= 2 ,,, 2221111 ω+==ω−=ω+= avvvlvvlvv lrlr where jm, weight and the moment of inertia мr; wj the moment of inertia of a wheel; rl ττ , the moments, developed by the drives of the left and right wheel; rl uu , the controls acting on drives; hd , parameters of drives. 4. fuzzy control an alternative approach to the control of any processes is to investigate the control strategies employed by the human operator. an operator usually expresses his control strategy linguistically as a set of heuristic decisions. the fuzzy logic provides the means of expressing linguistic rules in a form suitable for computer implementation. in this section, the design and implementation of a fuzzy controller for the mobile robot in slippery environment is presented. zadeh [16] expanded the concept of the traditional boolean logic set to that of a fuzzy set. he stated that a fuzzy set is a class of objects with a continuum of grades of membership. fuzzy logic is based on fuzzy set theory and provides means for representing partial belief situations. it is a generalization of a conventional boolean logic. it defines the union, intersection, etc. operations of fuzzy sets in a similar way to boolean logic and classic set theory. in problems involving signal processing, the signal is usually transformed to the frequency domain, processed and then transformed back to the time domain. this allows the use of processing techniques which would otherwise be too complicated in the time domain. similarly, fuzzy control system design (see fig.2), consists of a fuzzification step, fuzzy inference and a defuzzification step. fuzzification involves transforming inputs from crisp values to fuzzy variables. fuzzy inference is the process of applying fuzzy rules to the fuzzified input values and calculating the fuzzy outputs. in the last step, a defuzzifier transforms the fuzzy outputs back to the crisp values. figure 3 shows the configuration of a pid type fuzzy controller of the form. ∫++= t idp dttekekeku 0 )(& (3) where pk , dk and ik are the proportional, integral and derivative gains, respectively, u and e are the control signal and the error between the reference signal and the plant output. dr.nabil hassan hadi/al-khwarizmi engineering journal ,vol.1, no. 2,pp 41-51 (2005) 45 fig.٢. fuzzy logic controller architecture fig.٣ pid type fuzzy logic. imagine that you are the operator who is trying to maintain programmed trajectory by varying the controls acting on drive motors, you will come up with some control rules similar to what follows to drive the mobile robot. if e is and ∆ e is and 2∆ e is then ∆ u is (4) each rule takes three inputs and produces one output, control action for the left and right drives. 5. slipping diagnostics the control system structure for мr with various chassis configurations are described in detail in works [4,5]. it includes the block of base control providing improvement of a program trajectory in the assumption of absence full slipping and the block of suppression of sliding which in case of occurrence slipping corrects or completely changes base control so that whenever possible is fast to restore the normal coupling wheels with a surface. the information of occurrence is necessary for algorithms of correction of base slipping control and, whenever possible, the information on type slipping. thus, the system of diagnostics which should establish the fact of occurrence slipping and classify its type will be necessary.the system of diagnostics assumes to install on a mr accelerometers, the position and orientation of which axes of sensitivity, depend on the mr layout. the system consists of several channels depend on the number of accelerometers dr.nabil hassan hadi/al-khwarizmi engineering journal ,vol.1, no. 2,pp 41-51 (2005) 46 used. accelerometers are designed to measure the angular speeds of wheels in the assumption of absence slipping and then compared to the appropriate programmed acceleration. if movement of mr occurs without slipping signals differences (errors) are close to zero. acceptable signals differences of allowable levels are fixed by threshold devices. after filtering the information from the block of diagnostics, the possibility of occurrence slip and its type are determined automatically. 6. results of modelling the dynamics behavior of mr eq(2) when moving on a circle of radius dρ with constant speed dv will studied. where illustrating, the behavior of the system of diagnostics for the elementary case when fuzzy base control uses only a proportional regulator of speed ( ) ( ) ( ) ( ) 2 rv̂, 2 ˆkvv̂k,h d 1u w lrdd vllll ω+ω = ω−ω−−− =τω+τ= ω (5) ( ) ( ) ( ) ( ) l2 rˆ, 2 ˆkvv̂k,h d 1u w lrdd vrrrr ω−ω =ω ω−ω+−− =τω+τ= ω where ωk,kv factors of strengthening; ddd v ρ=ω program angular speed. in the considered example, two accelerometers where suggested to use with mutually perpendicular axes of sensitivity placed at the centre of weights on longitudinal and cross axes of mr. measured signals from accelerometers, calculated in the assumption of absence slipping, and look like displacement of the centre of weights ( ) ( )( ) l r e r e w lrlr v w lr 4 ˆ, 2 ˆˆ ˆ 2ωωωωωω +− = + =ω && (6) the fuzzy logic block of a system of diagnostics forms a target signal from threshold devices of each of channels. such simplified procedure quickly allows to determine the fact of occurrence slipping, but does not allow to classify its type. at the beginning of slipping (occurrence of slip) the block of suppression of sliding in coordination reduces the program linear and angular speeds acting on a regulator of speed (5). the following situation was modelled. within first 55 seconds mr moved on a circle in conditions of good coupling wheels with a surface. further these conditions have changed to the worse, i.e. sudden entrance a slippery surface was modelled. figure4 illustrates process of mr movement with a control system in which the system of diagnostics of suppression of sliding does not work. in figure4a, the trajectory of movement of mr is given. it is visible, that at deterioration of conditions of mr leave its trajectory and move with new trajectory of smaller radius circle. in figure4b, the longitudinal velocity of the mr. it is visible, that it precisely reflects the fact of occurrence slipping and fully complies with diagrams of right and left wheel speeds and the trajectory of the mr(fig. 4,c and d). dr.nabil hassan hadi/al-khwarizmi engineering journal ,vol.1, no. 2,pp 41-51 (2005) 47 -2 -1 0 1 2 3 4 0 1 2 3 4 5 6 7 x, m y, m 0 20 40 60 80 100 120 140 160 180 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 time, s ve lo ci ty , m /s (a) (b) 0 20 40 60 80 100 120 140 160 180 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 time, s an gu la r v el oc ity ra d/ s 0 20 40 60 80 100 120 140 160 180 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 time, s ve lo ci ty v r a nd v l, m /s (c) (d) fig. ٤. movement mr with the switched off system of slip diagnostics fig.5 illustrates the process of mr movement with switching on the system of diagnostics and the block of suppression of sliding. under same conditions, it is shown that the trajectory of motion is not broken. because of inertia, within several seconds, mr goes with allowable slipping, then again starts to move without slipping on a circle of the given radius dρ , but with smaller speed which size is set by the block of suppression of sliding. from diagrams it is visible, that the logic signal on an output of a system of diagnostics (figure5f) fully complies with the movement described above (see fig 5,b,c,d and e). dr.nabil hassan hadi/al-khwarizmi engineering journal ,vol.1, no. 2,pp 41-51 (2005) 48 -3 -2 -1 0 1 2 3 -2 -1 0 1 2 3 4 x, m y, m 0 20 40 60 80 100 120 140 160 180 0 1 2 3 4 5 6 7 8 9 10 time, s sl ip o cc ur an ce (a) (b) 0 20 40 60 80 100 120 140 160 180 0 0.05 0.1 0.15 0.2 0.25 time, s ve lo ci ty v 1, m /s 0 20 40 60 80 100 120 140 160 180 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 time, s an gu la r v el oc ity , r ad /s (c) (d) dr.nabil hassan hadi/al-khwarizmi engineering journal ,vol.1, no. 2,pp 41-51 (2005) 49 0 20 40 60 80 100 120 140 160 180 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 time, s ve lo ci ty v r a nd v l, m /s 0 20 40 60 80 100 120 140 160 180 -2 0 2 4 6 8 10 12 14 16 time, s co nt ro l r ig ht a nd le ft dr iv e si gn al s (e) (f) fig. ٥. mr movement with the included system of slip diagnostics 7. conclusions in this paper modelling problems of control for mr with pid fuzzy logic control system, and algorithm of sliding suppression is developed. it allows to carry out researches on features of dynamics of mr with various configurations. an overall performance of a control system is studied. the study has identified some of the potential benefits of using fuzzy logic controllers. in comparison with the modern control theory, fuzzy logic is simpler to implement as it eliminates the complicated mathematics of the modelling process and uses a set of control rules instead. fuzzy control is also more robust to parameter variations. there are numerous accelerator control problems which involve phenomena that are not amenable to simple mathematical modeling. there is also a class of problems that are simple in nature but are difficult to codify for algorithmic control. the study allow further researches by changing the characteristics and parameters of mr, the control system and conditions of interaction of wheels with a surface. also a convenient graphic interface, will allow to analyze the diagrams of processes and to deduce animation image of mr during movement. for mr with two-wheeled configuration the system of diagnostics carried out the functions only on an establishment of the fact of occurrence slipping. authentic classification the slipping types was not possible because of complexity of dynamics movement of mr at the conditions of slipping. despite of it, even the establishment of the slip occurance the control system allowes to correct the state and it is reliable to keep mr near to the programmed trajectory. for mr with the increase of number of accelerometer appeared possible not only to establish the fact of occurrence slipping, but also to allocate the basic types slipping. it has allowed to enter more effective correction of base control and to increase quality of improvement of a program trajectory. 8. references [1] golombek, m. p., 1998, “mars pathfinder mission and science results,” proceedings of the 29th lunar and planetary science conference. 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[12] freund e., mayr r. “nonlinear path control in automated vehicle guidance,” ieee transactions on robotics and automation. 1997. vol. 13. 1, pp. 49-60. [13] ackermann j. yaw “disturbance attenuation by robust decoupling of car steering,” 13th triennial world congress, san francisco, usa, 1996. [14] bakker e.t., pacejka h.b., and linder l. “a new tire model with an application in vehicle dynamic studies,” sae technical paper no. 870421. 1982. [15] canudas de wit c., olsson h., astrom k.j., lischinsky p. “a new model for control of systems with friction,” ieee transactions on automatic control, vol. 40, no. 3, march 1995. [16] l. zadeh, "fuzzy sets," in selected papers by l. a. zadeh . dr.nabil hassan hadi/al-khwarizmi engineering journal ,vol.1, no. 2,pp 41-51 (2005) 51 السیطرة على ألیھ باستخدام المنطق المبھم في محیط زلق نبیل حسن ھادي.د كلیة الھندسة / قسم المیكانیك :الخالصة متنقلة عند تعرضها إلى حاله مفاجئه في على الحركة الذاتية ألليه fuzzy logicالسيطرة باستخدام المنطق المبهم مثال على ذلك هو دخول المفاجىء لالليه . ثها في هذه الدراسةتم بح, الظروف ألتفاعليه بين العجالت والسطح مثل هذه اآلليات تكون مهمة في المحيط الذي يكون فيه تواجد األشخاص خطرا وبالتالي يكون من المهم . منطقه زلقه twoذات عجلتي قياده في هذا البحث تم بناء ومحاكاة النموذج الديناميكي ألليه .اآللياتعلى هذه السيطرةجدا wheels driver باستخدام المنطق المبهم وكذلك تم تصميم نظام السيطرة االليه لهذه االليهfuzzy logic , حيث تم . تطبيقه على اليه تسير في مسار دائري زلق وتمكنت من الحفاظ على هذا المسار design and implementation of a broad band frequency synthesizer ali m. n. hassan/al-khwarizmi engineering journal ,vol.2, no. 2 pp 15-31(2006) 15 design & implementation of high switching & low phase noise frequency synthesizer ali m. n. hassan information & communications engineering dept. al khwarizmi college of engineering university of baghdad (received 14 november 2005; accepted 4 april 2006) abstract: this research describes the design & implementation of frequency synthesizer using single loop phase lock loop with the following specifications: frequency range (1.5 – 2.75) ghz,step size (1 mhz), switching time 36.4 µs, & phase noise @10 khz = 92dbc & spurious -100 dbc the development in i.c. technology provide the simplicity in the design of frequency synthesizer because it implements the phase frequency detector(pfd) , prescalar & reference divider in single chip. therefore our system consists of a single chip contains (low phase noise pfd, charge pump, prescalar & reference divider), voltage controlled oscillator , loop filter & reference oscillator. the single chip is used to provide the following properties :  low power consumption.  small size, light weight.  flexibility in selecting crystal oscillator frequencies to fit into the system frequency planning.  high reliability. the application of this synthesizer in frequency hopping systems, satellite communications & radar because it has high switching speed ,low phase noise & low spurious level. 1.introduction the generation of accurate waveforms plays a crucial role in almost all electronic equipment, from radar to home entertainment equipment. a frequency synthesizer is defined as a system that generates one or many frequencies derived from a single time base (frequency reference), in such a way that the ratio of the output to the reference frequency is a rational fraction. the frequency synthesizer output frequency preserves the long-term frequency stability (the accuracy) of the reference and operates as a device whose function is to generate frequencies that al-khwarizmi engineering journal al-khwarizmi engineering journal, vol.2,no.2,pp 15-31 (2006) ali m. n. hassan/al-khwarizmi engineering journal ,vol.2, no. 2 pp 15-31(2006) 16 are multiples of the reference frequency (multiples by a single or many numbers). these multiples may be whole or fractions; but since only linear operations are used (in the frequency domain), these numbers can only be rational. a frequency synthesizer, as defined here, can thus generate an output frequency of, say, x/y (where x and y are whole numbers) times the reference frequency. pll synthesizers can be found in the most sophisticated radar systems or the most demanding satellite communications terminals as well as in car radios and stereo systems for home entertainment. the pll is a feedback mechanism locking its output frequency to a reference. pll synthesizers gained popularity for their simplicity and economics. frequency synthesizers use a pll to copy, multiply, or divide a crystal reference source. the stability and phase noise properties of the crystal reference oscillator are preserved within the loop bandwidth of the pll[2]. 2.frequency synthesizer requirements the basic requirement set for a frequency synthesizer by any telecommunications system is that the synthesizer must be able to generate all required frequencies with a sufficient accuracy. the output signal of an ideal frequency synthesizer is a pure sinusoid, i.e. a delta function in the frequency domain. the output spectrum of a real synthesizer, however, consists of a number of nonideal components in addition to the sinusoidal component. figure 2.1 illustrates these components, as well as other parameters, whose specifications will be derived in the following sections. 2.1.phase noise it is divided into two types: 2.1.1phase noise at small offset frequencies in the transmitter, the major contributor to the phase error is the frequency synthesizer generating the local oscillator frequency. the close-in phase noise manifests itself as random fluctuations in the phase of the local oscillator signal, which then translate directly to fluctuations in the phase of the transmitted signal, i.e. random phase error. let us assume that the frequency synthesizer is a second-order pll, i.e. the phase noise rolloff is -40 db per decade for offset frequencies beyond the loop bandwidth. let us also assume that the phase noise floor of the synthesizer is low enough to be ignored as a contributor to the total integrated noise. this assumption is only valid for narrow band systems, where the pll bandwidth is only about an order of magnitude smaller than the channel bandwidth. let us denote the phase noise at small offset frequencies by l close-in , the phase-locked loop bandwidth by b pll , and the channel bandwidth of the system in question by b channel . we can now approximate the square of the phase error with[3]. eq(2.1) ali m. n. hassan/al-khwarizmi engineering journal ,vol.2, no. 2 pp 15-31(2006) 17 solving for the close-in phase noise, we get: eq (2.2) shows that increasing thepll bandwidth leads to a tighter specification for the close-in phase noise. 2.1.2.phase noise at large offset frequencies the phase noise of the frequency synthesizer at large offset frequencies is almost always specified. the reason for this is a phenomenon commonly referred to as reciprocal mixing. the phase noise tail of the local oscillator signal mixes with undesired interfering signals, and the mixing result ends up at the same intermediate frequency as the wanted signal, thus impairing the signal-to-noise ratio. the reciprocal mixing phenomenon is illustrated in figure 2.2. the spectrum converted to the intermediate frequency can be represented as the convolution of the received rf spectrum and the spectrum of the local oscillator signal (equation (2.3)). eq(2.3) since the interfering component can be much stronger than the wanted signal, the phase noise power of the local oscillator at the same offset frequency must correspondingly be much lower to maintain a useful signal-to-noise ratio of the down converted signal. the specification for the local oscillator power at a given offset frequency can be derived from the power levels of the wanted signal and the interfering signal, and the signal-to-noise ratio required to guarantee signal reception at the desired bit error rate: eq(2.4) the last term of the equation is an approximation, assuming that the mean value of the phase noise over the channel bandwidth can be approximated with the phase noise value at the center point of the channel. 2.2.spurious tones spurious tones are unwanted components in the frequency synthesizer output spectrum that are not noise-like. the vco is essentially a frequency modulator, and periodic signals at the vco control line will result in an output signal with discrete fm sidebands. the requirement for the maximum spurious power derives from the blocking specification of the telecommunications ali m. n. hassan/al-khwarizmi engineering journal ,vol.2, no. 2 pp 15-31(2006) 18 system. a spurious tone at a given offset mixes the neighboring channel at the same offset down to on top of the wanted channel. the spurious power must therefore be low enough to provide an adequate signal-to-noise ratio (snr) in the output of the receiver. a number of nonidealities in the pll itself will generate interfering signals in the vco control line. all of these phenomena will result in periodic signals at the pll reference frequency, and thus in spurs at an offset of f ref from the carrier. the dominant spurious-generating nonidealities in a typical pll are mismatch between the up and down currents in the chargepump and charge injection through the switches in the chargepump. also, the leakage currents of the chargepump and the vco may be significant contributors. figure 2.3 shows how the mismatch between the up and down currents in the chargepump results in a periodic signal in the vco control line. in this case, the up current is slightly larger than the down current. the pll feedback mechanism tries to keep the mean value of the vco control voltage (v c ) constant, and therefore the down pulses from the phase detector will be slightly longer to compensate for the smaller current. the resulting net output current of the chargepump (i cp ) is then low pass filtered in the loop filter. despite of the filtering, the vco control voltage still clearly shows a periodic beat at the reference frequency, which will in turn result in spurious tones[4]. the charge injection through the chargepump switches is illustrated in figure 2.4. the digital up and down signals from the phase detector will have relatively fast rise and fall times, and thus harmonic components at very high frequencies. some of these highfrequency components will be injected to the chargepump output node through the gate-source and gate-drain capacitances (c gs and c gd ) of the switch transistor. the capacitances c gs and c gd depend on the gate-to-source and gate-to-drain voltages v gs and v gd , respectively. therefore, the charges injected through the up and down switches will depend on the chargepump output voltage. the up and down charges will be equal for one single output voltage value. for all other output voltages, there will be a net charge injected to the output of the chargepump. the pll will compensate for this excess charge very much in the same way as the chargepump mismatch in figure 2.3, and a periodic beat at the reference frequency is generated. the other phenomenon typically generating reference spurs is the loop filter leakage. when the pll is locked, the chargepump is neither pumping up nor down for most of the time. ideally, a chargepump in this state represents an infinite impedance towards the loop filter. likewise, the input impedance of the vco control node is ideally infinite. in practice, however, both the chargepump switches and the vco control node (typically connected to a varactor diode) will have finite impedances, and there will be a small leakage current that will change the control voltage of the vco slightly either up or down. the pll will compensate for the leakage, and thus a periodic beat at the reference frequency is again generated. in pll’s using a discrete loop filter, the leakage currents are normally not a problem. the loop filter capacitors are very large, and a small leakage current will change the loop filter voltage only negligibly. since ali m. n. hassan/al-khwarizmi engineering journal ,vol.2, no. 2 pp 15-31(2006) 19 the spurious power will depend on the actual shape of the interfering waveform it is first assumed that the disturbance on the vco control line appears as narrow, rectangular pulses having a width δt and a height δv. inserting the fourier series expansion of the rectangular waveform into the time domain representation of the vco output waveform yields the following equation for the vco output: eq(2.5) equation (2.5) indicates sidebands at ±nω ref from the carrier, where ω ref is the phase comparison frequency. typical approaches to reducing the problem are using large capacitors in the loop filter (to keep δv to a minimum), and minimizing k vco to minimize the modulation index. however, both remedies have their downsides as well: increasing the loop filter capacitance requires increasing the chargepump current proportionally; k vco cannot be lowered indefinitely, because the tuning range still needs to cover the desired frequencies plus process, temperature and supply voltage variations. 2.3.settling time in modern telecommunications systems, the synthesizer often has strict requirements for settling time, defined as the time it takes for the synthesizer to settle to a given accuracy after a frequency step. in time division multiple access (tdma) systems, the settling time specification is mostly due to the desire to use the same synthesizer for both transmit and receive modes, thus saving power and area. in frequency hopping systems, the relatively frequent changing of the channel frequency is used to make sure that enough packets are received correctly even if a part of the frequency band would be blocked by strong interferers. independent of the reason for changing the transmit or receive frequency, the system specifications usually set a limit on how fast this needs to be done, and this can be directly translated into a synthesizer settling time requirement[5]. in the phase-locked loop, being a lowpass control system by nature, the settling time is always inversely proportional to the loop bandwidth. other constraints, such as stability, reference suppression, and close-in phase noise normally set the upper limit for the loop bandwidth. on the other hand, the settling time specification typically sets the fundamental lower limit. using the standard notation of feedback theory, a second-order loop has a closedloop transfer function of ali m. n. hassan/al-khwarizmi engineering journal ,vol.2, no. 2 pp 15-31(2006) 20 eq(2.6) where ξ is the damping factor, and ω n is the natural frequency. from the step response of the closed-loop transfer function we can derive the minimum required natural frequency for the loop to settle within a given maximum relative frequency error δ (absolute frequency error divided by the total frequency step) in a given switching time t sw to be eq(2.7) assuming the damping factor ξ to have a value of 0.707 (optimal value in most cases), we can express the minimum loop crossover frequency as eq(2.8) 3.system design & implementation it is required to design of microwave fast hopping frequency synthesizer to use in communications & radar , that has the following basic requirements:  frequency range 2.0 – 2.7 ghz  step size at least 1mhz  switching time less than 1msec  spurious o/p -70 dbc  phase noise @1khz -50 dbc to achieve the above requirements with lowest cost & complexity , the system design as a single loop pll frequency synthesizer to obtain the following specifications:  frequency range 1.5 – 2.75 ghz  step size 1 mhz  switching time less than 1msec a schematic diagram of the system is sketched by adipllsim version(2.7) software as shown in figure (3.1).the system consists of the following components :  single chip contains digital pfd(phase frequency detector) ,charge pump, reference divider & prescalar.  voltage controlled oscillator(vco) . ali m. n. hassan/al-khwarizmi engineering journal ,vol.2, no. 2 pp 15-31(2006) 21  loop filter.  reference oscillator. 3.1.single chip the single chip consists of a low noise, digital phase frequency detector (pfd), a precision charge pump, a programmable reference divider, programmable a counter and b counter, and a dual-modulus prescaler (p/p + 1).this chip is used for simplifying system architecture and reducing cost. in our system the single chip synthesizer is selected adf4106 from analog device company because it has low phase noise, low spurious & low power consumption. the functional diagram of the single chip is shown in figure (3.2)[10]. the components of the single chip will illustrate as follows:  phase frequency detector (pfd) and charge pump: the pfd takes inputs from the r counter and n counter (n = bp + a) and produces an output proportional to the phase and frequency difference between them. figure 3.3 is a simplified schematic. the pfd includes a programmable delay element that controls the width of the antibacklash pulse. this pulse ensures that there is no dead zone in the pfd transfer function and minimizes phase noise and reference spurs. two bits in the reference counter latch, abp2 and abp1, control the width of the pulse.  prescalar(p/p+1): the dualmodulus prescaler (p/p + 1), along with the a counter and b counter, enables the large division ratio, n, to be realized (n = bp + a). the dual-modulus prescaler, operating at cml levels, takes the clock from the rf input stage and divides it down to a manageable frequency for the cmos a counter and b counter. the prescaler is programmable. it can be set in soft-ware to 8/9, 16/17, 32/33, or 64/65. the a counter and b counter, in conjunction with the dual-modulus prescaler, make it possible to generate output frequencies that are spaced only by the reference frequency divided by r. the equation for the vco frequency is eq(3.1) where : f vco is the output frequency of the external voltage controlled oscillator (vco). p is the preset modulus of the dualmodulus prescaler (8/9, 16/17, etc.). ali m. n. hassan/al-khwarizmi engineering journal ,vol.2, no. 2 pp 15-31(2006) 22 b is the preset divide ratio of the binary 13-bit counter (3 to 8191). a is the preset divide ratio of the binary 6-bit swallow counter (0 to 63). f refin is the external reference frequency oscillator. for our system the prescalar is programmed to 16/17.  r – counter: the 14-bit r (reference) counter allows the input reference frequency to be divided down to produce the reference clock to the phase frequency detector (pfd). division ratios from 1 to 16,383 are allowed. 3.2.voltage controlled oscillator the vco must be cover the range (1.5 2.75) ghz with lower phase noise. therefore we select rqre -1500-27500 from ralton company to satisfy these requirements. it has the following specification:  tuning voltage ,dc :(1-20)volt.  typical o/p power : 7 dbm.  d.c. power supply vcc: 10 volt with tolerance ±0.25. 3.3.reference oscillator the reference oscillator has a frequency 10 mhz & the reference counter (rcounter)in the single chip synthesizer must be set to 100 to obtain on 100khz step size. 3.4.loop filter design the loop filter is a passive 2nd order filter which is selected in the system because it has the following properties:  the least complex loop filter.  smallest resistor thermal noise.  largest capacitor next to vco to minimize the impact of vco input capacitance.  maximum resistance to variation of vco gain & pfd gain the loop filter impedance is defined as the voltage output at vco to the current injected at the charge pump in the single chip synthesizer. the expression of loop filter impedance z(s) & the corresponding poles & zeros are shown below at various filter orders is shown below[1]: z(s) = (1 + st2) /( a0(1+st1)(1 +st3)(1+st4)) eq(3.2) where a0 is filter coefficient & equal to (c1 + c2) for passive loop filter for passive 2nd order loop filter, the input impedance: z(s) = (1 +sc2 r1) / (s(c1 + c2)(1 + (sc1c2r1) / (c1 +c2))) eq(3.3) from the above equations , it should be clear : t2 = r1c2 , t1 = r1 c1 c2/a0 & a0 = c1 + c2. then c1 = a0 t1/t2 , c2 = a0 c1 , r1 = t2/c2. t2 = ζ / (wc 2 t1) where ζ = optimization factor = 1.005 , wc = 2 л fc, fc = loop b.w., t1 ={[ (1+ ζ )2 tan2 φ + 4 ζ ]1/2 (1+ ζ) tan φ}/ (2 wc) , φ = phase margin & a0 = {(k kvco ) / (nwc 2)} / {[(1+ wc 2 t22) / (1 + wc 2 t12) ]1/2} for the system : c1 = 12.2 nf , r1 = 5.46 kω , & c2 = 12.8 nf 4.results ali m. n. hassan/al-khwarizmi engineering journal ,vol.2, no. 2 pp 15-31(2006) 23 a system is simulated by adipllsim version 2.7 software & we obtain the following results: 4.1. phase noise the phase noise of pll frequency synthesizer & vco is shown in the following table: offset frequency (hz) pllfrequency synthesizer vco 100 -92.85 -171.3 1k -92.4 -151.3 10 k -92.74 -131.3 100 k -90.19 -114.8 1 m -117.0 -132.5 the c/c of phase noise with frequency for the system at output frequency 2.03 ghz is shown in figure 4.1 1k 10k 100k 1m 10m frequency (hz) -160 -150 -140 -130 -120 -110 -100 -90 p h a s e n o is e ( d b c /h z) phase noise at 2.03ghz the vco c/c is simulated by adisimpll software is shown in figure 4.2. figure 4.1. the c/c of phase noise with frequency for the system ali m. n. hassan/al-khwarizmi engineering journal ,vol.2, no. 2 pp 15-31(2006) 24 1k 10k 100k 1m 10m offset frequency -160 -150 -140 -130 -120 -110 -100 -90 -80 -70 ss b ph as e no is e (d bc /h z) vco phase noise at 2.03ghz 0 2 4 6 8 10 12 14 16 18 20 voltage (v) 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0 f re q u e n c y ( g h z) vco freq vs volts 0 2 4 6 8 10 12 14 16 18 20 voltage (v) 40 50 60 70 80 90 100 110 120 130 k v (m h z/ v ) vco kv vs volts 4.2.reference spurious noise and jitter calculations include the first 10 ref spurs first three spurs: -100 dbc -100 dbc -100 dbc 4.3.switching speed the switching speed for frequency change from 1.5ghz to 2.75ghz is 36.4 µs the transient response for system from 1.5ghz to 1.65 ghz is shown in figure 4.3: figure 4.2. the c/c of vco phase noise with frequency, vco freq. with voltage & vco kv with voltage respectively ali m. n. hassan/al-khwarizmi engineering journal ,vol.2, no. 2 pp 15-31(2006) 25 0 10 20 30 40 time (us) 1.50 1.52 1.54 1.56 1.58 1.60 1.62 1.64 1.66 f re qu e nc y (g h z) frequency 5.discussion the operation of implemented synthesizer was verified and various performance parameters have been checked &it is found they are within the system requirements . the first parameter is the phase noise , table 4-1 shows the highest phase noise in the system is -92.74dbc/hz at 10khz offset & the over shoot for phase noise @ offset frequency 100 khz as shown in figure 4.1 results from that the loop b.w. for pll is 100 khz. the second parameter is the switching time is shown in figure 4.3 is 36.4 µs is something close to theoretical value (4msec)in section 3.2.2 & the overshoots in figure 4.3 results from the transient case of frequency change & this transient case must be very small in time. the third parameter is a reference spurious , is illustrated from the results is -100dbc & this value satisfy the system requirements for spurious. 6.conclusions a frequency synthesizer with frequency range (1.5 – 2.75) ghz using single loop frequency synthesizer was design & implement. the development in i.c. technology provide the simplicity in the design of frequency synthesizer because it implements the pfd , prescalar & reference divider in single chip. this single chip has the following properties :  low power consumption.  small size, light weight.  flexibility in selecting crystal oscillator frequencies to fit into the system frequency planning.  high reliability. from the results of this research, we conclude that the switching speed can be increase by increase loop bandwidth this results in increasing the reference frequency but it causes in increasing the step size. there are many techniques to implement this system. figure4.3. the transient c/c of system from 1.5ghz to 1.65ghz ali m. n. hassan/al-khwarizmi engineering journal ,vol.2, no. 2 pp 15-31(2006) 26 we would present these techniques with their disadvantages. there is direct digital synthesis (dds) can be used to implement this system but it has drawbacks , its main disadvantage include the fundamentals limit of b.w. (maximum frequency o/p is less than one half the clock rate). expanded b.w. requires higher clock rates , & therefore faster logic and more critical manufacturing & testing processes. there is hybrid technique (dds as reference oscillator) can be used to implement this system successfully but it has high cost relative to implemented system. multi loop pll can satisfy this frequency range but these loops with their mixers increase spurious o/p signals , power dissipation , cost , size & complexity. the major benefits of implemented system over the multi loop frequency synthesizer will illustrate in a fair comparison with previous work in 2003 includes design of an integrated cmos pll frequency synthesizer consists of two loops. system parameters frequency range(ghz) step size switching time phase noise spurious level number of loops multi loop implemented in 2003 2.4 – 2.5 1mhz 30 µs -83 db/hz @10 khz -60 dbc 2 system implemented. 1.5 – 2.75 1mhz 36.4 µs -92db/hz @10 khz -100dbc 1 7. references 1. dean banerjee “pll performance , simulation & design” 4th edition, 2005. 2. goldberg, bar-giora.,” digital frequency synthesis demystified”, llh dean banerjee “pll performance , simulation & design” 4th edition, 2005 3. j.a crawford, “frequency synthesizer deign handbook” , artech house, norwood ,1994. 4. j. craeninkx & m. steyaert, “wireless cmos frequency synthesizer design” kluwer boston ,1998. 5. li lin, “design techniques for high performance integrated frequency synthesizers for multi-standard wireless communication applications” university of california , phd, thesis,2000 ali m. n. hassan/al-khwarizmi engineering journal ,vol.2, no. 2 pp 15-31(2006) 27 6. lascari lance, “accurate phase noise prediction in pll frequency synthesizers” applied microwave & wireless , vol. 12 , no. 5 , may2000 7. mike curtin and paul o’brien. “phase locked loops for high frequency receivers and transmitters,” analog dialogue volume 33, 1999. 8. roland e. best. “phase-locked loops”, mcgraw-hill (1993). 9. mannassewitsch vadim “frequency synthesizers theory & design”third edition, wiley & sons. new york, 1987. 10. the analog device adf41xx series data sheet,2005. ali m. n. hassan/al-khwarizmi engineering journal ,vol.2, no. 2 pp 15-31(2006) 28 figure 2.2. reciprocal mixing figure 2.1. non ideal components in the output spectrum of a pll frequency synthesizer. ali m. n. hassan/al-khwarizmi engineering journal ,vol.2, no. 2 pp 15-31(2006) 29 figure 2.4 charge injection in the chargepump switches. figure 2.3 periodic signal generated by the charge pump. ali m. n. hassan/al-khwarizmi engineering journal ,vol.2, no. 2 pp 15-31(2006) 30 ce 10 dvdd 15 gnd 9 cp 2 fin a 6 ref in 8 notesadf4106: 1. vp is the charge pump power supply 2. vp >= vdd 3. ce must be high to operate 4. tssop pinouts shown 5. consult manufacturer's data sheet for full details muxout 14 gnd 4 gnd 9 le 13 data 12 clock 11 avdd 7 vp 16 adf4106 / adf4107 gnd 3 fin b 5 r set 1 rset 5.10k r1 3.42k c2 12.8nf c1 1.95nf ct 0f vco rqre-1500-2750 v supply reference tcxo10 gnd v+ f out figure 3.1. schematic diagram of system ali m. n. hassan/al-khwarizmi engineering journal ,vol.2, no. 2 pp 15-31(2006) 31 figure 3.2. functional diagram of single chip figure 3.3. schematic diagram of pfd & charge pump ali m. n. hassan/al-khwarizmi engineering journal ,vol.2, no. 2 pp 15-31(2006) 32 تصميم وبناء مركب ترددات ذو سرعة تحويل عالية وضوضاء طوري قليل علي محمد نوري قسم هندسة المعلومات واالتصاالت كلية هندسة الخوارزمي / جامعة بغداد :الخالصة يصف هذا البحث تصميم وبناء مركب ترددات باستخدام طريقة اقفال ااطور احادي الدورة وبالمواصفات التالية : .مايكرو 63ميكا هرتز ،زمن تحويل 0( ميكا هرتز، واقل سعة قفزة 0501-0011مدى الترددات الخارجة ) -د الخارج.ومستوى الطفيليات هرتز من الترد 01111ديسبيل عند (92-)ثانية ومستوى ضوضاء طوري ديسبيل 011 كاشف التردد التطور الحاصل في الدوائر المتكاملة جهز البساطة في تصميم مركب الترددات وذلك ألنه دمج والطور ،ومقسم التردد الثنائي ، ومقسم التردد في شريحة رقيقة واحدة. لذلك منظومتنا تتكون من شريحة تحتوي رددات وطور ذو ضوضاء طوري قليل،مضخة شحنة دقيقة،مقسم ترددات مبرمج ، ومقسم كاشف ت(على كل من ( مبرمج( مرشح ترددات واطئة ،مذبذب ترددات ذو سيطرة جهدية، ومذبذب مرجعي. p/( p+1)تردد ثنائي) هذه الشرحة الرقيقة التي تحتوي كل من كاشف ترددات وطور مقسم ترددات مبرمج ومقسم تردد ثنائي تم استخدامها وذلك ألنها تمتلك المواصفات التالية: قلة في استهالك القدرة حجم صغير ووزن خفيف مرونة في اختيار تردد مذبذب البلورة بحيث يناسب خريطة التردد للمنظومة وثوقية عالية ر التطبيقات لهذا المركب في منظومات القفز بالتردد ، واتصاالت األقمار االصطناعية، والرادا وذلك ألنها تمتلك خاصية ضوضاء طوري قليل وسرعة تحويل عالية ومستوى طفيليات اقل. final2 azad r. karee /al-khwarizmi engineering journal ,vol.1, no. 1,pp 19-25 (2005) ١٩ abstract: a modification to cascaded single-stage distributed amplifier (cssda) design by using active inductor is proposed. this modification is shown to render the amplifier suitable for high gain operation in small on-chip area. microwave office program simulation of the novel design approach shows that it has performance compatible with the conventional distributed amplifiers but with smaller area. the cssda is suitable for optical and satellite communication systems. al-khwarizmi engineering journal al-khwarizmi engineering journal, vol.1, no.1,pp 19-25, (2005) a new structure for cascaded single-stage distributed amplifier using proposed active inductor loads keyword: micro electronic, microwave, amplifier, distributed amplifier. 1 introduction: the conventional distributed amplifier (cda) was proposed in 1948 and originally applied to vacuum tubes [1]. with the development of monolithic microwave integrated circuits (mmic) during 1960’s [2], the das have been realized by using on-chip transistor technologies such as mosfet’s [3], and mesfet’s [4], as well as gaas mesfet [5]. more recently many other technologies were introduced to the monolithic distributed amplifier world[6]. a schematic representation of a da is shown in figure(1). in this structure, the parasitic capacitors of the transistors (cgs and cds) together with the inductors (lg and ld) make two artificial transmission lines (gate and drain lines). as a result, the effect of these capacitors will be absorbed into low-pass filter segments of the transmission lines then it is possible to obtain amplification over much wider bandwidth. the drawback of this amplifier is limited gain-bandwidth due to its optimum number of stages [7]. high gain can be achieved by cascading several single stage distributed amplifiers. the circuit structure of cssda is shown in figure (2). it is essentially a cascade connection of single–stage distributed amplifiers with the omission of idle gate and drain termination for the intermediate stages [8]. the amplifier’s gate transmission line is formed by the lumped inductors li and the gate capacitance cgs of t1 where as the inductors ld along with the drain capacitance cds of tn serve as the drain artificial line. these input and output lumped transmission lines match the amplifier to the source and load impedance ro over the entire bandwidth. the available power gain expression is given by [9]: 4 2)1(22 o n i n m rrgg − = …….(1) where gm is the transconductance of the active devices. the input and output artificial lines possess much larger bandwidth compared with that of the inter-stage loads, therefore the bandwidth of the amplifier is limited by the cutoff frequency of internal stage (t2 -tn-1). azad r. kareem control and systems engineering dept./university of technology azad r. karee /al-khwarizmi engineering journal ,vol.1, no. 1,pp 19-25 (2005) ٢٠ 342 )1 1 1 () 1 1 ()2 1 2 ( 2 )1 1 1 ( 1 4 112122 2 112 mmmmmm ww nnnn cic −++++−+= − −− − − − − it is given by: ……….(2) where crlm ii 2/= , cdscgsc += , and crw ici /1= is the cutoff frequency of the stages if there is no inductance in the drain line of the amplifier. equation (2) can be written as follow: wc = wci . γ ……….(3) table (1) lists some values of m and their corresponding to various values of γ for n=4. referring to equation (1), it is clear that high gain is obtained with large ri. since li=mri 2 c, large ri mandates large li for given m and c where by the size of the on-chip circuit will be increased. the goal of this paper is to study this problem and to put a suggestion for an effective size reduction for the on-chip circuit. 2 implementation of on-chip inductor: the main problem associated with the design of microwave integrated circuits, such as amplifiers, oscillators and mixers in which the inductors are essential elements is the physical size of these elements. both resistors and capacitors are easy to implement. considerable effort has gone into the design of the inductor implementation. figure(3) shows the layout for different types of spiral inductors. for a given shape, an inductor is completely specified by the number of turns (n), the turn width (w), the turn spacing (s), and the turn diameters: din and dout , where davg = 0.5(din + dout). there are many expressions for the inductance value, one of them is given by a monomial expression that has the following form [10] 54321 αααααβ sndwdl avgout= ……….(4) where the coefficients β and αi are layout dependent. for a square, β = 1.62 * 10-3 , α1 = 1.21 , α2 = 0.147 α3 = 2.4 , α4 = 1.78 , and α5 = 0.03. it is clear that the value of l depends on the size of its layout. 3 proposed active inductor implementation: figure (4-a) shows a single stage distributed amplifier. the introduction of a current source transistor ml in the load circuit alters its frequency dependent impedance, figure (4-b). =lz = x x i v +r lcgw rmg s 21 1 − + )( jwl )( rlgjwrz ml +≈ …….(5) actl jwlrz += where rlgl mact = …….(6) equation (6) shows that the amount of amplification achieved in the inductance value is (gmr) which means that the effective inductance is (gmr) greater than the actually implemented one. this allows the use of a large value inductance in the circuit but with a small on-chip area. although the new structure of the inductance composed of two elements instead of one, the transistor has a very small area compared with the area of the inductor. 4 cssda with active inductor loads: previous cssda’s have used large inductances at the drains. increasing table.1 m γ response 0 0.9 0.5 1 1.53 1.34 no inductive load maximum bandwidth maximally flat azad r. karee /al-khwarizmi engineering journal ,vol.1, no. 1,pp 19-25 (2005) ٢١ the gain of the amplifier is achieved either by increasing the value of ri in equation (1), or by increasing the number of stages (n). since m = li/ri 2c, then large ri mandates large li for a given m and c. on the other hand increasing n with a given value of li means increasing the size of the amplifier. these two points yield circuits with larger on-chip area. however, figure (5) shows the schematic of a cssda designed with a new type of inductors called “active inductors” , each one composed of an active device (mi) plus a small inductor. such implementation of inductors reduces the overall on-chip circuit area without any effect on the performance of the amplifier. the available power gain can also be determined using equation (1). a rf signal from a matched generator is coupled by the transconductance of the active device (ti) at each stage, and finally terminated by the matched output load port. at each stage, the rf signal will be boosted and terminated by the load resistor (ri). the amplified signal is valid only up to the cut-off frequency, which is controlled by the elements values of equation (2). to demonstrate the effectiveness of the developed methodology, a four stage amplifier is designed with gain about 23db and bandwidth of 10 ghz. the elements values are: ri = 40 ω , li = 0.42 nh , c = 0.6 pf , and gm = 0.06 1−ω . the circuit was implemented using microwave office program. the s-parameters extracted from the measurement data are shown in figure (6). the circuit is also implemented using active inductors (with li = 0.1 nh and gm = 0.15 1−ω ) and its measurement data are shown in figure (7). it is interesting to note that, compared to the conventional cssda, the cssda with active inductor loads achieve the same results (forward gain s21 the reflection losses s11 and s22) but with smaller inductance. 5 conclusion: in this paper a new design of cascaded single-stage distributed amplifier using the novel active inductor loads is demonstrated. the new structure has unique benefits over the conventional cssda in terms of high gain and area saving. the structure also allows very simple design procedure. a four-stage amplifier was implemented using the developed technique to achieve gain ≈23 db and bandwidth ≈ 10 ghz. hence, the cssda design is suitable for optical and satellite applications. references: e. ginzton, w. hewlett, j. jasberg and j. noe., “distributed amplification”, proc. ire. vol.36, pp. 956-969, aug. 1948. 1. r. a. pucel, “design considerations for monolithic microwave circuits”, ieee trans. mic. the. tech., vol.29, pp. 513534, june 1981. 2. f. schar, “distributed amplifiers using microstrip ”, int. j. electronics, vol.34, pp. 721-730, 1973. 3. w. jutzi, “a mesfet distributed amplifier with 2 ghz bandwidth”, proc. ieee, pp. 1195-1196, june 1969. 4. e. w. strid and k. gleason, “ a dc-12 ghz monolithic gaas fet distributed amplifier ” ieee trans. mic. the. tech., vol.30, pp. 969-975, july 1982. 5. m. green, s. lee, k. chu, j. webb, and f. eastman, “high efficiency monolithic gallium nitride distributed amplifier ” , ieee microwave letters, vol.10, pp. 270272, july 2000. azad r. karee /al-khwarizmi engineering journal ,vol.1, no. 1,pp 19-25 (2005) ٢٢ 6. t. wong, “fundamentals of distributed amplification”, artech house, 1993. 7. a. worapishet, m. chongcheawchamnan, and s. srisathit, “broadband amplification in cmos technology using cascaded single-stage distributed amplifier”, electronics letters, vol.38, pp. 675676, july 2002. 8. j. y. liang and c. s. aitchison, “gain performance of cascade of single-stage distributed amplifiers”, electronics letters, vol.31, pp. 1260-1261, july 1995. 9. s. mohan, m. hershenson, p. boyd, and h. lee, “simple accurate expressions for planar spiral inductances”, ieee j. of solid-state circuits, vol.34, pp. 1419-1424, oct. 1999. figure(1) schematic circuit of n-stages cda figure(2) schematic circuit of n-stages cssda azad r. karee /al-khwarizmi engineering journal ,vol.1, no. 1,pp 19-25 (2005) ٢٣ figure(3) on-chip spiral inductor realizations: (a) square, (b) hexagonal, (c) octagonal, and (d) circular. figure(4) single stage of da.(a)simple common source amplifier.(b)the amplifier with active inductor.(c)the equivalent model of the active inductor. vdd ml (a) (b) (c) azad r. karee /al-khwarizmi engineering journal ,vol.1, no. 1,pp 19-25 (2005) ٢٤ figure(5) proposed cssda figure(6) simulated s-parameters in the cssda with passive inductors (li= 0.42 nh) figure(7) simulated s-parameters in the cssda with active inductors (li= 0.1 nh) 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 frequency (ghz) dis -20 -15 -10 -5 0 5 10 15 20 25 30 35 40 db(|s[1,1]|) cssda db(|s[2,1]|) cssda db(|s[2,2]|) cssda 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 frequency (ghz) dis -20 -15 -10 -5 0 5 10 15 20 25 30 35 40 db(|s[1,1]|) cssda db(|s[2,1]|) cssda db(|s[2,2]|) cssda azad r. karee /al-khwarizmi engineering journal ,vol.1, no. 1,pp 19-25 (2005) ٢٥ هيكلة جديدة للمضخمات التوزيعية باستخدام احمال حثية فعالة زاد رحيم كريمآ لـوجـيةوالجامـعة التكن/ قسم هندسة السيطرة و النظم :الخالصة البحث يتناول دراسة موجزة لمضخمات أشارات الترددات المايكوية ذات النطاق الواسع جدا باستخدام مبدا (cascaded single stage distributed amplification) كبير في تطبيقات االتصاالت لالذي يستخدم بشك هذا النوع من المضخمات يضم في تركيبته محاثات في دائرة . البصرية و انظمة االتصاالت عبر االقمار الصناعية (integrated circuits) ةان حجم المحاثة هو احد اهم المشاكل التي ترافق تصميم الدوائر المتكامل. الخرج من المضخمات بحيث اصبحت تستخدم نوع مستحدث من المحاثات تقنيةال ههذتم تطويرلذلك , لالنظمة المايكروية التشكيل .الهدف االساسي منها هو انها تحتاج مساحة اقل عندما تصمم على الدوائر المتكاملة " محاثات فعالة"سميت الذي هو مختص باالنظمة المايكروية وكانت نتائج (microwave office)ام برنامج الجديد للمضخم أختبر باستخد . التقليدي مع فرق انه يحتاج حجوم اصغر للمحاثات للمضخم الجديد مطابق بكفائته المضخماالختبار هو ان failure modes and effect analysis of steam soroor k. hussain al-khafaji /al-khwarizmi engineering journal ,vol.1, no. 2,pp 64-85 (2005) ٦٤ al-khwarizmi engineering journal al-khwarizmi engineering journal, vol.1, no.2,pp 64-85, (2005) design of a programmable system for failure modes and effect analysis of steam-power plant based on the fault tree analysis soroor k. hussain al-khafaji dr. nihad m. a. al-rahman mechanical eng. dept. / university of technology electrical eng. dept./ college of engineering / university of baghdad dr. zuhair i. ahmad aldauod mechanical eng. dept. college of engineering / university of baghdad (received 25 april 2005; accepted 2 october 2005) abstract: in this paper, the system of the power plant has been investigated as a special type of industrial systems, which has a significant role in improving societies since the electrical energy has entered all kinds of industries, and it is considered as the artery of modern life. the aim of this research is to construct a programming system, which could be used to identify the most important failure modes that are occur in a steam type of power plants. also the effects and reasons of each failure mode could be analyzed through the usage of this programming system reaching to the basic events (main reasons) that causing each failure mode. the construction of this system for fmea is depending on the logical relationships of the fault tree analysis for the systems that contained in the power station. the designing of such system could be used as an assistance tool for the specialist user (the power engineer) in identifying of all reasons and effects for any type of failures. so this is help to fastening the repairing operation of the identified failure mode to improve the efficiency of operating system as represented by the maintainability, which is a function of system reliability. the selection of the steam type of power generation systems for the application of this study, because this type is the most common type of iraqi power plants. while such the designed system could be programmed to be use in another types of industrial systems. keywords: fault tree, reliability, maintainability, industrial systems, failure mode and effect analysis, diagnostic expert system, steam power plant 1. introduction with the increasing of complexity degree for the industrial systems, there is an importunate need to the application of developed techniques in operating and maintaining of such systems. the failure modes and effect analysis (fmea) is one of modern technique that is especially applied with complex systems to facilitate the identification process of the systems failure modes and to analyzing of their reasons and effects. the research deals with the power plant as a significance type of industrial systems. where the reliability improvement of such systems has respective importance since the objective function of the power plant is to produce energy with reliable factors and available quality as planned as possible during the required period of time. then the maintainability improvement has the main role for reliability enhancement, which is defined as “the probability that a failed component or system will soroor k. hussain al-khafaji /al-khwarizmi engineering journal ,vol.1, no. 2,pp 64-85 (2005) ٦٥ restore or repaired to a specified condition within a period of time when maintenance is performed in cordance with prescribed procedures.” (1) although thermal generating facilities are aging, flexible operation in response to changes in the demand for electrical power is required. to extend the life and manage the operation and control activities of power generation unit, the information and network technologies have become their important role to ensure the safety functioning and control of the unit operation. also, the focusing on the application of advanced preventive maintenance technology and scheduled inspections of the unit facilities such as the boiler, steam turbines, gas turbines, and other machinery used in thermal power generation, which were controlled by computerizing diagnostic systems. all of these facilities lead to strengthen preventive maintenance and increase the efficiency of the power unit production. 2. the method of fault tree analysis “fault tree analysis (fta) is reliability/safety design analysis technique, which starts from consideration of system failure effects, referred to as top events. the analysis proceeds by determining how these can be caused by individual or combined lower level failures or events”. (1) by the fta technique many events that interact to produce other events can be resulted using simple logical relationships such as (and, or,etc.), and these relationships permit a methodical building of a structure that represents complicated systems. when the tree structure has been established, subsequent analysis is deductive and takes two forms: (2) × qualitative analysis to reduce the tree to a logically equivalent form in terms of specific combinations of basic events (primary faults) sufficient to cause the undesired top event to occur. each combination will be a “minimal cut set” of failure modes for the tree. (a minimal cut set is a set of events, which cannot be reduced in number, whose occurrence causes the top event). × quantitative analysis, which consists of transforming its established logical structure into an equivalent probability form and numerically calculating the probability of occurrence of the basic events. standards symbols are used in constructing a fta to describe events and logical connections, these symbols are shown in table-a. and/or gates are simply graphical symbols, which represent boolean operation on the various events. the or gate is equivalent to the boolean symbol “+” and represent the union of the events attached to the gate. the and gate is equivalent to the symbol “.” representing the intersection of events soroor k. hussain al-khafaji /al-khwarizmi engineering journal ,vol.1, no. 2,pp 64-85 (2005) ٦٦ table-a: standard fault tree logic and event symbolism: (2) , (3) event representations logic operations the rectangle identifies an event that results from the combination of fault events through the input logic gate. and gate describes the logical operation whereby the coexistence of all input events is required to produce the output event. the circle describes a basic fault event that requires no further development. or gate defines the situation whereby the output event will exist if one or more of the input events exist. the triangles are used as a transfer symbols. a line from the apex of the triangle indicates a transfer in and a line from the side or bottom denotes a transfer out. inhibit gates describes a causal relationship between one fault and another. the input event directly produces the output event if the indicated conditional input defines a state of the system that permits the fault sequence to occur, and may be either normal to the system or result from failures. the diamond describes a fault event that is considered basic in a given fault tree. the possible causes of the event are not developed further because the event is of insufficient consequences or the necessary information is unavailable. the circle within the diamond indicates a sub-tree exists, but that sub-tree was evaluated separately and the quantitative results inserted as though a component. soroor k. hussain al-khafaji /al-khwarizmi engineering journal ,vol.1, no. 2,pp 64-85 (2005) ٦٧ 3. the functional description of steam-power unit with the application of fault tree analysis technique through the studying of the operating nature of steam-power generation unit, one recognized that the unit operational system could be classified into three major operational subsystems. these subsystems are interconnected with each other in a specified manner to give the required output of the entire unit’s system, which is the planned capacity of electrical power. these major subsystems are the mechanical, electrical, and control, and each one of them is consisting of a combination of components and subsystems, which are working dependently on each other to obtain the required function. in the following, a description to each one of the major subsystems is given. 3.1 the mechanical system this system consists of the following major components: (4) × the boiler contains the furnace where burning fuel (oil, natural gas, and crude oil) and heats water to make steam. the boiler is the device meant for producing steam under pressure. × the super-heater is used to superheat the steam before passing through the boiler to the prime mover. × forced draft fans, for efficient combustion enough air has to be supplied. the chimney provides natural draught, and additional draught by forced draft (f.d.s) fans. × the economizer, where the gaseous products of combustion give most of their heat to the water in the tubes of the boiler and superheater, and in order to make use of the remaining heat thereby heating the feed water in the economizer tubes. × air-heaters arrangement used to provide initial heat to the air before it is admitted to the furnace. × the turbine changes steam’s heat energy into mechanical energy. steam pushes blades rotating on a bar, causing it to spin at high speed. the generator changes the mechanical energy into electrical energy. the spinning bar of the turbine causes a huge magnet in the generator to rotate past copper bars producing electric current. × the condenser, where steam after expansion through the turbine goes through the condenser. the use of condenser improves the efficiency of power plant by decreasing the exhaust pressure of the steam below atmosphere. another advantage of the condenser is that condensed steam can be recovered and this provides a source of good and pure feed water to the boiler. × circulating water pumps, to provide the required quantity of cooling water for condensing steam in the condenser. where these pumps are normally installed on the source of water (river) to supply water throughout the year. × the hydraulic system, it is an important system that used for controlling the quantity of steam supplied to the turbine. this system used to supply the hydraulic oil with high pressure directly to an electric motor, which controls the automatic motion (open and closed) of the supplied steam valves to the turbine. × the serve valve controls the quantity of hydraulic oil that pumped by the hydraulic pump. all failure modes of the mechanical system have been analyzed through the application of fault tree (ft) technique to describe the logical relationships among the failure events reached to the top event of this system, which is the turbine operating failure. the fault tree analysis of this system is shown in fig. (1), where the failure symbols are explained in table-b. soroor k. hussain al-khafaji /al-khwarizmi engineering journal ,vol.1, no. 2,pp 64-85 (2005) ٦٨ 3.2 the electrical system the electrical system of steam power unit is consists of the following major components: (5) × turbine-generator shaft, the turbine has single shaft with several stages (may be 17 stages), rotates with a velocity reaching to 3000 rpm, by input steam of temperature 4820c with pressure of 58 bar. the generator shaft is connected directly with turbine shaft so that it rotates with velocity of 3000 rpm and the generated voltage is usually 11kv. the generator is 3-phase ac. × the 11kv circuit breaker (c.b), is designed to control the generated voltage of 11kv, which is supplied to the electrical system. × 11/132kv main transformer, this transformer is used for the transformation from 11/132kv that supplied to the 132kv c.b when the generator is generating and vise versa when the generator is stopped. × rectifier, to convert the 125v a.c into 125v d.c that is required for the 125v d.c system to supply d.c voltage for some important equipment such as protection, control, and emergency oil pumps. × 11/3.3kv auxiliary transformer, this transformer is used for the transformation from 11 to 3.3kv that required for operating of some auxiliary units (high & low voltage equipment). × 3.3kv c.b, to control the power that fed to the 3.3kv busbar (b.b). × 3.3kv b.b, to supply the required voltage for operating of high voltage motors in the system. × 3.3/0.38kv load center transformer, to obtain 0.38kv that is fed to the 0.38kv b.b. × 0.38kv c.b, to control the power that is fed to the 0.38kv b.b. × 0.38kv b.b, to supply the required voltage for operating the low voltage motors in the system. the failure modes of the electrical system have been analyzed with the application of the ft technique as described in fig. (2), and the failure symbols are explained in table-c. 3.3 the control system the control system of the steam power unit could be divided into three subsystems as follows: × the steam turbine control (stc) system, this part of control system is responsible for the speed and load of the turbine. the circuit board assemblies of this system contain the electronic printedcircuit boards (cards), which are provide the operational control and turbine-generator protective features in the system. the stc system consists of the following parts: asp/ov sp/o sp board: it is sensitive to the speed of turbine through their probes, which are connected to the turbine. binterface and set-point select boards: these boards are responsible for the setting sensitivity of the speed, load and load limiting. c dual set-point board: is used to give final signals for speed and load. d speed summer board: it takes the above signals as inputs and gives one signal as an output, which enters the servo amplifier board. eipl summer board: it is sensitive to the boiler pressure and gives signal that indicates the proper pressure. fservo amplifier board: used to control the operating activity of servomotor until executing the order. g3 khz board: it amplifies the signal coming from the servo valve to the servo amplifier board. soroor k. hussain al-khafaji /al-khwarizmi engineering journal ,vol.1, no. 2,pp 64-85 (2005) ٦٩ almost all types of faults, which occur in this part of control system, are the failures of cards for the above components due to the failure of the integrated circuits boards. then, a trip signal are resulted from these failures such as the failure of set-point select board, or the dual set-point board, or the servo amplifier board, or the 3khz board. and all of these trip signals lead to the failure of servo valve. the servo valve controls the output high-pressure hydraulic fluid flow in proportion to the magnitude and polarity of the input direct current command signals, which control the regulation valves to control the steam that goes to the turbine. × spec 200 control system, this system is used to control most of operating processes during the running of the power generation unit. this system consists of several important units or subsystems, which forming the basics of control functions, such as: adrum level control system, which control the normal level of water in the boiler drum. bairflow control system, which controls the flow of air that is entering to the boiler for combustion process, through its control on the forced draft fans (fd fans). coil pressure control system: this system controls the oil pressure, which is supplied to the boiler furnaces and required for combustion process. dda level control system, which controls the water level in da drum and makes it in a normal level. × furnace safety and supervisory system, this system is known by the abbreviation (fsss). it is responsible for the boiler running process and the boiler safety operation, through its controlling the fast closing valves for the fuel lines, which are supplied to the boiler. the running of any protection system of the unit is due to the resulted orders from this system. since this system has several types of trip signals, so that if any of these signals results, the system will immediately emit a signal to the protection system of boiler to stop operating. also any fault signal, which results from the electronic boards (cards) of this system, will lead to stopping the boiler. the faulty signals, which are produced from the fsss, do comprise the following: aturbine trip signal. bflame failure trip signal. closs of fuel trip signal. dhigh furnace pressure trip signal. eloss of f.d fans trip signal. fhigh or low level trip signal. gairflow low trip signal. hloss of 125v d.c trip signal. fig. (3) shows the fault tree construction of components failure and the faulty signals for the three parts of control system, and the symbols of this figure are explained in table-d. the top events of the three systems (mechanical, electrical, & control) are related with each other in or-gate leading to top event of whole unit system (unit shutdown). 4. the designing of knowledgebased representation for the reasoning programs of the power unit fault trees the state-space search is an important kind of control strategies that could be used to represent the level of procedural knowledge control. “state spaces can either be searched in a forward direction (or forward chaining) by starting at the initial states and applying the operators to find a soroor k. hussain al-khafaji /al-khwarizmi engineering journal ,vol.1, no. 2,pp 64-85 (2005) ٧٠ path to a goal state, or in a backward direction (or backward chaining) by starting with goal and applying the inverse of the operators to find a path to the initial state.” (6) the level of knowledge-based can be represented by some means such as the production rules, and the logical representations. “ the production rules are often simply called production. a production is a condition-action pair and defines a single chunk of problemsolving knowledge. the condition part of the rule is a pattern that determines when that rule may be applied to a problem instance. the action part defines the associated problem-solving step.”(6) also the knowledge-based level can be represented in “first order predicate logic, if the formulas are suitably interpreted. the program may contain several different ways to establish predicate statements corresponding to the and/or graph. the solution of a problem is presented as a set of statements that are found by doing a depth-first search of the corresponding and/or graph until an instantiation of a set of assertions is found that provides a solution graph.” (7) to control the fault tree procedural knowledge, the state space search of forward direction (forward chaining) has been utilized at the level of knowledge control representation of the unit-systems fault trees. then, the production of if-then rules based on the and/or graph have been used to represent the knowledge-based system. figures (5, 6, & 7) show the state spaces search to identify the top events from the procedural knowledge-based representation of mechanical, electrical, and control systems fault trees, respectively. the set of production rules of isolating the mechanical system failure causes reaching to the system top event (mf1) that could inferred from fig. (5), would be represented as follows: 3mf10mf9mf8mf7mf6mf5mf4mf ⇒∨∨∨∨∨∨ 11mf15mf14mf13mf12mf ⇒∨∨∨ 19mf21mf20mf ⇒∨ (1) 16mf19mf18mf17mf ⇒∨∨ 1mf16mf11mf3mf2mf ⇒∨∨∨ where the symbol ∨ means or . from fig. (6), the inferred set of production rules to isolate the electrical system failure causes reaching to the top event (ef1) would be represented as follows: 4ef8ef7ef6ef5ef ⇒∨∨∨ 9ef11ef10ef ⇒∨ 12ef14ef13ef ⇒∨ 9.12ef12ef9ef ⇒∧ (2) 2ef9.12ef4ef3ef ⇒∨∨ 17ef19ef18ef ⇒∨ 15ef17ef16ef ⇒∨ 1ef51ef2ef ⇒∧ where the symbol ∧ means and. and the set of production rules, which inferred from fig. (7) to isolate the control system failure causes reaching to the top event (cf1) would be represented as follows: soroor k. hussain al-khafaji /al-khwarizmi engineering journal ,vol.1, no. 2,pp 64-85 (2005) ٧١ 2cf8cf7cf6cf5cf ⇒∨∨∨ 3cf16cf15cf14cf13cf12cf11cf10cf9cf ⇒∨∨∨∨∨∨∨ (3) 4cf20cf19cf18cf17cf ⇒∨∨∨ 1cf4cf3cf2cf ⇒∨∨ the three systems top events (mf1, ef1, & cf1) are connected with each other reaching to the whole unit-system top event (uf) through the production rule as represented by: uf1cf1ef1mf ⇒∨∨ (4) function (4) could be deduced from the knowledge-based representation of the unit-system fault tree as that shown in fig. (8). 5. the programmable system that designed for the failure mode and effect analysis “the failure mode and effect analysis (fmea) can be described as a systematic way of identifying failure modes of a system, item or function, and evaluating the effects of the failure modes on the higher level. the objective of fmea is to determine the causes for the failure modes and what could be done to eliminate or reduce the chance of failure. this technique is an effective way to identify component failures or system malfunctions, and to document the system under consideration.”(8) the programmable system is designed to be used as an expert system to help the specialist user (power plant engineers) in identifying the failure modes and to analyze their reasons and effects on whole unit system. the designed system consists of a set of programs, and all are written in matlab programming system. in the following a brief explanation for some of the designed programs with their flowcharts: q the first program is known by “rcs” since it works as a reasoning control structure for the unit-system fault trees to cognizing the failure causes and the effect analysis for whole system of the steam-power unit reaching the unit-system top event the (unit shutdown). fig. (9) shows the flow chart of this program. q the second program is denoted by “ftree”, which is specialized in explaining the logical relationships among the failure modes for the whole unit-system as described in the fault tree diagrams. also the running of this program gives the minimal cut sets of failure events, where such events should given more attention since the occurrence of any one of the will leading to the failure of whole system (top event). fig. (10) shows the flow chart of this program. q “dbp” denotes another program that is contained in the programming system and it is designed to be use as an input-output database program. this program contains all the necessary input database (failure & repair rates) that is required to quantify the reliability and availability of all individual components or events of the unit-system fault trees. then, the output results of this program could be used as an output database that is required for other analytical programs of the system. the analytical procedures of this program are out the range of this research. q another sets of programs are designed in a systematic way such as the backward chaining of the unit-system fault trees that is beginning from higher level (top event) reaching to lower level (primary events). the running of these programs is appeared in a shape of windows, which are controlled by different types of pushbuttons. all these windows are set in the programming system that is specialized to perform the function of fmea of the steam-power plant. some of the system windows of the failure mode analysis for the steampower plant are shown in figs. (11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, & 22). soroor k. hussain al-khafaji /al-khwarizmi engineering journal ,vol.1, no. 2,pp 64-85 (2005) ٧٢ 6. discussion and conclusion v for complex type of industrial systems such as the power plant, the fault tree analysis (fta) has a respective importance in recognizing all types of failure modes, which affect their performance efficiency, and deducing the reasons of system malfunctions. v the effectiveness of the designed programmable system for fmea is mainly depending on the precision of knowledge, which were obtained from the expertise of operating staff in the power plant. therefore, there is substantial need to involve a large number of experts (engineers and specialists) who are operating in the different departments of the power plant as consultants in constructing the knowledge-based system of the fmea programming system. v the knowledge of the designed programmable system could be modified to be applied in other types of complex industrial systems to identify their failure modes and analyzing their reasons and effects to improve the maintenance activities and then enhancing the reliability of the system performance. v the fmea may be considered as a reasoning technique of a diagnostic expert system. this technique describes the logical relationships among the failure events of the system fault tree. v the matlab programming system could be considered as an effective tool in designing such programming systems to solve the different types of industrial engineering problems, since it has the ability of programming with both of linguistic and analytic statements. 7. suggestion for future work v the designed programmable system of this work could be developed to be working on line with systems of the power plant. such development requires the connection of the systems and components with appropriate sensors for sensing any error that might occur in the operating systems of the power plant, then converting them into signals to be translated into commands in a central control unit. such control unit should comprise computers network that is programmed on the fmea programming system to have the ability of translating of the error commands into failure modes, and to analyze the reasons and all possible effects of each failure mode. v the programmable system is designed specifically for the failure modes analysis of the steam type power units, and could be developed to cover other types of thermal power units depending on the extension of the constructed knowledge-based system. soroor k. hussain al-khafaji /al-khwarizmi engineering journal ,vol.1, no. 2,pp 64-85 (2005) ٧٣ fig. (1) the fault tree construction of mechanical system failure modes mf1 (turbine operating failure) mf16 mf 17 mf 18 mf19 mf 21 mf 20 mf11 mf 12 mf 13 mf 14 mf 15 mf 2 mf 3 mf 4 mf 5 mf 6 mf 7 mf 8 mf 9 mf 10 soroor k. hussain al-khafaji /al-khwarizmi engineering journal ,vol.1, no. 2,pp 64-85 (2005) ٧٤ table-b: symbols explanation of failure modes or events of the mechanical system fault tree of fig. (1): event symbol explanation event symbol explanation mf1 mechanical system top event (turbine operating failure) mf12 air removal pumps failure mf2 boiler feed water pumps failures mf13 circulating water pumps failure mf3 boiler failure mf14 condenser tubes dirty mf4 loss of air combustion fans mf15 condensate water pumps failure mf5 max. or min. water level mf16 hydraulic system failure mf6 boiler tubes leakage mf17 hydraulic oil pressure pumps failure mf7 heavy oil control valve failure mf18 oil level low mf8 air combustion register system failure mf19 servo valve failure mf9 rotating air heater failure mf20 servo valve filter dirty mf10 heavy oil pressure pumps failure mf21 hydraulic oil control valve closed mf11 condenser failure fig. (2) the fault tree construction of electrical system failure modes ef 16 ef 18 ef 19 ef 3 ef 4 ef 5 ef 6 ef 7 ef 8 ef 9 ef 12 ef 10 ef 11 ef 13 ef 14 ef 15 ef 2 ef 17 ef 1 (no power generation) soroor k. hussain al-khafaji /al-khwarizmi engineering journal ,vol.1, no. 2,pp 64-85 (2005) ٧٥ table-b: symbols explanation of the failure modes or events of the electrical system fault tree of fig. (2): event symbol explanation event symbol explanation ef1 electrical system failure (top event) ef11 trip of differential relay 1 ef2 the generator stop of power generation ef12 auxiliary trr failure ef3 stator earth fault ef13 trip of differential relay 2 ef4 loss of excitation ef14 auxiliary trr earth fault ef5 rotor failure ef15 132 kv c.b failure ef6 excitation c.b failure ef16 failure in pressure of gas “sf6” ef7 rectifier failure ef17 air compressor unit failure ef8 carbon brushes failure ef18 leakage in the compressor unit pipes ef9 main trr failure ef19 compressor failure ef10 main trr earth fault figure (3) the fault tree of control system failure modes cf 1 (control system failure) cf 2 cf 5 cf 6 cf 7 cf 8 cf 4 cf 17 cf 18 cf 19 cf 20 cf 3 cf 9 cf 10 cf 11 cf 13 cf 16 cf 14 cf 15 cf 12 soroor k. hussain al-khafaji /al-khwarizmi engineering journal ,vol.1, no. 2,pp 64-85 (2005) ٧٦ table-c: symbols explanation for the failure modes or events of the control system fault tree of fig. (3): event symbol explanation event symbol explanation cf1 control system failure (top event) cf11 loss of fuel trip signal cf2 stc system failure cf12 high furnace pressure trip signal cf3 fsss failure cf13 loss of fd fan trip signal cf4 spec.200 system failure cf14 high & low drum level trip signal cf5 setpoint select board failure cf15 low air flow trip signal cf6 dual setpoint board failure cf16 loss of 125v dc trip signal cf7 servo amplifier board failure cf17 drum level control system failure cf8 3 khz board failure cf18 air flow control system failure cf9 turbine trip signal cf19 oil pressure control system failure cf10 flame trip signal cf20 da level control system failure figure (4) unit system fault tree mf1 mf3 mf16 mf2 mf19 mf11 mf4 mf10 mf18 mf5 mf8 mf12 mf6 mf7 mf20 mf9 mf21 mf17 mf13 mf14 mf15 fig. (5) the state space search to identify the top event from the knowledge-based representation of the mechanical system fault tree uf (unit shutdown) mf 1 cf 1 ef 1 soroor k. hussain al-khafaji /al-khwarizmi engineering journal ,vol.1, no. 2,pp 64-85 (2005) ٧٧ ef1 ef15 ef2 ef 9.12 ef3 ef4 ef16 ef17 ef5 ef6 ef7 ef12 ef9 ef18 ef19 ef13 ef14 ef12 ef11 fig. (6) the state space search to identify the top event from the knowledge-based representation of the electrical system fault tree cf1 cf4 cf2 cf5 cf3 cf20 cf6 cf19 cf7 cf8 cf18 cf17 cf9 cf15 cf16 cf12 cf14 cf10 cf11 cf13 fig. (7) the state space search to identify the top event from the knowledge based representation of the control system fault tree uf mf1 ef1 cf1 figure (8) the knowledge based representation of the soroor k. hussain al-khafaji /al-khwarizmi engineering journal ,vol.1, no. 2,pp 64-85 (2005) ٧٨ unit system fault tree a = 1, b = 0 yes disp('uf occured due to the events: mf or ef or cf') uf=b disp('uf=n o') end if uf = a else mf=b e else disp('uf is due to: ef or cf' ) input mf start if mf=a disp('mf = o c' ) disp('mf =n o') if ef=a disp('ef = o c' ) c else disp('ef=n o') e input ef ef=b c input cf disp('cf = oc' ) cf=b end else if cf=a disp(' cf = n o' ) end o c = event occurred ; n o = event not occurred ; mf = mech. syst. failure; ef = electrical sys. failure ; cf = control sys. failure figure (9) the flow chart of “ rcs” program soroor k. hussain al-khafaji /al-khwarizmi engineering journal ,vol.1, no. 2,pp 64-85 (2005) ٧٩ start disp('n=1=mft'), disp('n=2=eft'), disp('n=3=cft') input n if n=1 n=2 e n=3 c disp('mf=1=o, mf=0=n o') elseifelse mf19=mf20+mf21 mf16=mf17+mf18+mf19 input mf12=1 or 0: input mf13=1 or0 1 print mf19 print mf16 yes input mf20=1 or0 : input mf21=1 or 0 input mf17=1 or 0 : input mf18=1 or 0 1 input mf14=1 or 0 : input mf15=1 or 0 mf11=mf12+mf13+mf14+mf15 mf3=mf4+mf5+mf6+mf6+mf7+mf8+mf9+mf10 input mf2=1 or 0 2 print mf11 print mf3 input mf4=1 or 0 : input mf5=1 or 0 : input mf6=1 or 0 : input mf7=1 or 0 : input mf8=1 or 0 : input mf9=1 or 0 : input mf10=1 or 0 mf1=mf2+mf3+mf11+mf16 print mf1 mf1=0 disp('temft=o') disp('temft=n o') else yes if mf1=1 temft = top event of mech. sys. f t ; o = occurred ; n o = not occurred soroor k. hussain al-khafaji /al-khwarizmi engineering journal ,vol.1, no. 2,pp 64-85 (2005) ٨٠ 2 disp('m cs m ft ') in put m f1=1 or 0: inpu t ef 1=1 or 0: inpu t c f1 =1 or 0 te= m f1+ e f1+ cf1 if te =1 d isp('ute = o ') t e= 0 dis p('u te= n o ') end print te else yes disp('ef=1=o , ef =0=n o ') in put e f10=1 or 0 : input ef11 =1 or 0 e f9= ef 10+ef 11 p rin t ef 9 e f12=e f13+e f14 pr in t e f12 ef4 =e f5+e f6+ef 7+ ef8 p rin t ef 4 in put e f13=1 or 0 : inp ut e f14= 1 o r 0 e input ef5=1 or 0 : inp ut e f6= 1 o r 0 : inpu t ef 7= 1 or 0 : inpu t ef 8= 1 or 0 input ef3 =1 or 0 ef2 =e f3+ e f4+ ef 9*ef 12 p rin t ef 2 3 mcsmft = minimal cut set of mech. sys. ft ; ute = unit top event soroor k. hussain al-khafaji /al-khwarizmi engineering journal ,vol.1, no. 2,pp 64-85 (2005) ٨١ 3 input ef18=1 or 0 : input ef19=1 or 0 : ef17=ef18+ef19 input ef16=1 or 0 ef15=ef16+ef17 print ef17 print ef15 print ef1 ef1=0 disp('teeft=n o') ef1=ef2*ef15 if ef1=1 else yes disp('teeft= o') disp('mcseft') input mf1=1 or 0: input ef1=1 or 0: input cf1=1 or 0 te=mf1+ef1+cf1 4 4 print te disp('ute=n o') if te=1 te=0 disp('ute= o') end else yes c disp('cf1=1=o, cf1=0=n o') input cf5=1 or 0: input cf6=1 or 0: input cf7=1 or 0: input cf8=1 or 0 cf2=cf5+cf6+cf7+cf8 print cf2 input cf9+1 or 0 :input cf10=1 or 0: input cf11=1 or 0: input cf11=1 or 0: input cf12=1 or 0 : inputcf13=1 or 0: input cf14=1 or0 : input cf15=1 or 0: input cf16=1 or 0 5 5 cf3=cf9+cf10+cf11+cf12 +cf13+vf14+cf15+cf16 print cf3 input cf17=1 or 0: input cf18=1 or 0; input cf19=1 or 0: input cf20=1 or 0 cf4=cf17+cf18+cf19+cf20 print cf4 cf1=cf2*cf3*cf4 print cf1 if cf1=1 cf1=0 disp('tecft= n o') disp('mcscft') 6 6 else te=mf1+ef1+cf1 print te if te=1 te=0 disp('ute=n o') disp('ute= o') end input mf1+1 or 0: input ef1=1 or 0: input cf1=1 or 0 else yes disp('tecft= o') yes mcseft = minimal cut set of elect. sys. f t ; mcscft = m. c. s of cont. sys. ft teeft, tecft = top event of elect. & cont. systems. f t respectively fig. (10) the flow chart of “ftree” program soroor k. hussain al-khafaji /al-khwarizmi engineering journal ,vol.1, no. 2,pp 64-85 (2005) ٨٢ fig. (12) the second window of the system for basic failure mode identification fig. (13) the basic definition window mechanical system failure mode fig. (11) introduction window of the designed system fig. (14) the basic definition window of electrical system failure mode fig. (15) the basic definition window of control system failure mode fig. (16) main reasons window for the mechanical system top event soroor k. hussain al-khafaji /al-khwarizmi engineering journal ,vol.1, no. 2,pp 64-85 (2005) ٨٣ fig. (19) the main three reasons window for the control system failure fig. (20) the first reason window of the spec.200 system failure fig. (21) the first reason window of the stc system failure fig. (22) the first reason window of the fsss failure fig. (17) the main two reasons window of electrical system failure fig. (18) the main reasons window of generator failure soroor k. hussain al-khafaji /al-khwarizmi engineering journal ,vol.1, no. 2,pp 64-85 (2005) ٨٤ references: 1. o’connor p d. t., newton d., & bromely r., “practical reliability engineering”, 4th ed., john wiley & sons. ltd., 2002. 2. u.s nuclear regulatory commission, “fault treeappendix ii to reactor safety study”, wash-1400 (nureg75/014), october 1975. 3. mccormick n. j., “reliability and risk analysis-methods and nuclear power applications”, academic press, inc., 1981. 4. morse f. t., “power plant engineering”, litton educational publishing, inc., affiliated eastwest press pvt ltd, 1978. 5. soni m. l., gupta p. v., & bhatnagar u.s., “a course in electrical power”, dhanpat rai & sons, delhi, 1986. 6. luger g. f., “artificial intelligence and design of expert systems”, the benjamin/cummings publishing company, inc., 1998. 7. jackso p., “introduction to expert systems”, 3rd ed., addison wesely lonman ltd., 1999. 8. pentti h., & atte h., “failure mode and effects analysis of softwarebased automation systems”, (vtt industrial systems), stukyto-tr 190, www.stuk.fi, finland, august 2002. 9. assaf t., & dugan j.b., “automatic generation of diagnostic expert systems from fault trees”, university of virginia, 2003 rm. 10. kmenta s., & ishii k., “advanced fmea using behavior modeling for concurrent design of products and controls”, asme design engineering technical conferences, sept. 13-16, 1998, atlanta, ga. 11. konar a., “artificial intelligence and soft computing behavioral and cognition modeling of human brain”, crc press, inc., 2000. 12. ohman b., “failure mode analysis using multilevel flow models”, european union control association (euca), karlsruche, germany, 1999. http://www.stuk.fi soroor k. hussain al-khafaji /al-khwarizmi engineering journal ,vol.1, no. 2,pp 64-85 (2005) ٨٥ الفشل وتحليل التأثيرات لمحطة بخارية لتوليد الطاقة الكهربائية اعتمادا تصميم نظام مبرمج لتمييز أنماط على انشاء شجرة تحليل الخطأ زهير عيسى احمد داود.نهاد عبد الرحمن د.سرور خضر حسين الخفاجي د.د كلية اهلندسة/كلية اهلندسة قسم اهلندسة امليكانيكية/اهلندسة الكهربائية قسم قسم اهلندسة امليكانيكية جامعة بغداد جامعة بغداد اجلامعة التكنولوجية : الخالصة الرئيسة التي يمكن أن تحدث فـي ) العطالت(م مبرمج يمكن أن يستخدم في تمييز أنماط الفشل يهدف البحث الى إنشاء نظا كما ومن خالل استخدام هذا البرنامج يمكن تحليل التأثيرات واألسباب لكل نـوع مـن . هربائيةمحطة بخارية لتوليد الطاقة الك .أنواع العطالت وصوال الى ما يعرف باألحداث األساسية المسببة للعطل دا ، وذلك اعتمـا (fmea)لقد تم إنشاء هذا النظام الخاص بعملية تمييز أنماط العطالت وتحليل أسبابها أي ما يعرف بـ . الخاصة بكل نظام من األنظمة المكونة لمحطة توليد الطاقة (ftanalysis) على إنشاء شجرة تحليل الخطأ ان تصميم مثل هذا النظام المبرمج يمكن أن يستخدم من قبل مهندسي الطاقة في المحطة كوسيلة مساعدة في تسهيل عملية النظام الشامل لوحدة إنتاج الطاقة وهذا يساعد على اإلسراع فـي عمليـة تمييز نوع العطل مع تحليل أسبابه وتأثيراته على تشخيص العطالت وإصالحها وبالتالي تحسين كفاءة عمل المنظومة من خالل تطوير قابلية صيانة أنظمتها والتي تعتبر دالة من . ن تطبيقه في أنظمة صناعية أخرىومن خالل التعديل في برمجة المعرفة الخاصة بهذا النظام يمك. دوال موثوقية األداء <4d6963726f736f667420576f7264202d2034382d203536dae1c7c120e6e4e6d120e6c7d3cac8d1de> al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 14, no. 3, september, (2018) p.p. 4856 bioremediation of soil contaminated with diesel using biopile system noor mohsen jabbar* estabriq hasan kadhim** alaa kareem mohammed*** *,*** department of biochemical engineering/ al-khwarizmi college of engineering / university of baghdad ** treatment and disposal of hazardous waste directorate/ ministry. of higher education. and scientific. research *email: noormuhcin89@gmail.com **email: demaestabriq1@gmail.com ***email: alaa_univ@yahoo.com (received 14 october 2017; accepted 27 december 2017) https://doi.org/10.22153/kej.2018.12.009 abstract this study was focused on biotreatment of soil which polluted by petroleum compounds (diesel) which caused serious environmental problems. one of the most effective and promising ways to treat dieselcontaminated soil is bioremediation. it is a choice that offers the potential to destroy harmful pollutants using biological activity. the capability of mixed bacterial culture was examined to remediate the dieselcontaminated soil in bio piling system. for fast ex-situ treatment of diesel-contaminated soils, the bio pile system was selected. two pilot scale bio piles (25 kg soil each) were constructed containing soils contaminated with approximately 2140 mg/kg total petroleum hydrocarbons (tphs). the amended soil: (contaminated soil with the addition of nutrients and bacterial inoculum), where the soil was mixed with 1.5% of sawdust, then supplied with the necessary nutrients and watered daily to provide conditions promoting microorganism growth. unamended soil was prepared as a control (contaminated soil without addition). both systems were equipped with oxygen to provide aerobic conditions, incubated at atmospheric temperature and weekly sampling within 35 days. overall 75% of the total petroleum hydrocarbons were removed from the amended soil and 38 % of the control soil at the end of study period. the study concluded that ex-situ experiment (bio pile) is a preferable, economical, and environmentally friendly procedure, thus representing a good option for the treatment of soil contaminated with diesel. keywords: bioremediation, bio piles, diesel, soil pollution. 1. introduction oil pollution accidents had become a universal phenomenon and have caused serious environmental problems, such as the introduction of toxic compounds in food sources and changes in physical and chemical properties of the soil [1]. soil pollution with oil products is a permanent problem, and diesel is a common product for distillation of crude oil with a very complex composition. it consists mainly of low molecular weight alkanes and polycyclic aromatic hydrocarbons (pahs) [2] . with the increasing interest in the conservation of the environment, biological treatments have been improved and developed to clean up soils contaminated with hazardous compounds and have become a valuable alternative to physical and chemical treatments [3]. bioremediation is a successful procedure for cleaning up polluted sites by petroleum compounds because it is applicable to large areas, leads to the full removal of the contaminants, and cost-effective [4]. it can be defined as the conversion of toxic and chemically noor mohsen jabbar al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 4856 (2018) 49 complex organic compounds into non-toxic and inorganic compounds, such as carbon dioxide and water along with the accumulation of microbial biomass, through oxidation under aerobic conditions [5]. remediation technologies can be divided into ex-situ and in-situ methods [6]. amongst ex-situ methods available to bioremediate soils, bio piles have been described as an effective way to remove hydrocarbons which exist in diesel [7]. in bio piling, contaminated soils are accumulating above ground, and then the biological processes are motivating through aeration followed by addition of water and nutrient besides controlling temperature and ph [8]. aeration is carried out by the air compressor which drives the oxygen through the perforated tubes that are placed throughout the pile. compared to composting or land farming, the efficiency of mass transfer of water, nutrients and air in bio piles contributes a better contaminants removal strategy [9]. the aim of this study was to design a small scale bio piles system and to evaluate its efficiency to clean-up soil contaminated by diesel. 2. materials and methods 2.1 measuring the physio-chemical properties of soil physio-chemical analyses of the soil: water holding capacity, soil nitrogen, phosphorus, potassium (npk), and total organic content were determined according to the method of motsara and roy (2008) [10]. the ph was determined by taken 10 g of soil and placed in 20 ml distilled water. the suspension was mixed well and left for 10 minutes. then the measurement was done using ph electrode. particle size distribution of soil was determined by hydrometer method. all the analyses were conducted in the laboratory at the environment and water research and technology directorate/ ministry of science and technology. 2.2 preparation of contaminated soil twenty five kilogram of the uncontaminated soil sample was collected at a depth of (030) cm. soil was air dried, manually homogenized by removing any material such as stones. the soil passed through a 2-mm sieve and autoclaving at 121°c for 35min for two times [11]. the prepared soil was mixed by a hand trowel and contaminated with 1% of diesel/ soil (v/w) then thoroughly mixed to distribute diesel throughout the soil particles to achieve complete semi-artificial contamination. the contaminated soil was mixed with 1.5% sawdust to maintain moisture [16]. for the nutrient addition, the soil was fertilized with nutritious salts solution [(nh4)2so4 and kh2po4] in order to provide the c: n: p ratio of approximately (100:5:1) [12]. fresh bacterial suspension enriched with biodegradable isolates were sprayed on the soil surface and homogenized thoroughly with soil mixture [13].the treated soil was manually mixed with a clean trowel to enhance aeration and daily irrigated to maintain its moisture content within (50-60%) during the 35 days of experiment period. unamended contaminated soil (without additions) was used as the control. 2.3 bacterial inoculum specialized bacterial cultures had been developed in the laboratory to form a bacterial mixture capable of decomposing diesel contaminating the soil. the mixed culture was consisted of four selected bacterial isolates of sphingomonas paucimobilis, pentoae species, staphylococcus aureus, and enterobacter cloacae isolated from diesel-contaminated soil. these degradable bacteria after isolated and identified were cultivated under controlled conditions. for the ex-situ soil remediation , a dense suspension was prepared as shown below [14] : sphingomonas paucimobilis was inoculated into sterile tube containing 5 ml of normal saline solution until a cell concentration of 2.1 x 108 cfu.ml-1 (7 mcfarland standard) was reached. the 5 ml bacterial suspension was transferred into 100 ml of bushnell-haas medium (bhm). this was repeated using pentoae species instead of sphingomonas paucimobilis and so on. the mixed bacterial was prepared by mixing equal volumes of the culture of the above cell concentration for each isolate. these were used for field work [15]. 2.4 bio pile tanks several studies have been conducted on biopiles system of various sizes, ranged from pilot scale systems 100 kg [16] to field studies 500 kg of polluted soil [17]. the diverse nature of the soil components is difficult to capture in the laboratory scale as well the processes related to the distribution of oxygen and hydrocarbons through soil texture and soil moisture are varied with bio pile sizes. so for this study, 25kg was noor mohsen jabbar al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 4856 (2018) 50 chosen as the same amount was used by (sharma et al.,2014) [2]. at this mass, the soil can still represent field soil and its temperature will remain almost equal and not create parts of soil that have a high temperature which will negatively affect the bacteria. 2.5 experimental design two rectangular stainless steel tanks pilotscale bio pile were used, as shown in figure1. the dimensions of the tank are 52 cm in length, 33 cm wide and 26 cm deep. the soil was filled up to 15 cm from the bottom of the tank shown in figure 2 [7]. in order to provide aerobic conditions, an air compressor was connected to the tank. the air flow was controlled by valves and air flow rate was adjusted to 2l/h. the air was supplied at the bottom of the tank using stainless steel perforated tubes that passed along the tank. these tubes inside the tank are 60 cm long and 0.5 out-diameter with perforations 3 mm diameter, spaced 50 mm apart. to prevent soil from entering the ventilation pipes, they designed so that the holes were directed downward [18]. fig. 1. the pilot-scale stainless steel tanks of biopile system. fig. 2. the dimensions of the stainless steel biopile system. a: front view b: side view c-1: air supply tube c-2: cross section of air supply tube 2.6 monitoring the bioremediation experiment 2.6.1 determination of physiochemical parameters the ph was determined using a ph meter by suspending 2.5g of each soil sample into 20 ml of distilled water and mixing well. soil temperature was measured using a digital thermometer [19]. to ensure that soil moisture had not changed significantly and the supplied air had not dried soil so it was necessary to measure the moisture level of soil using a soil moisture probe. 2.6.2 the bacterial count the number of diesel-utilizing bacteria in soil was obtained using the method of pour plate as follows: each soil sample was prepared by adding 1gram of soil to 9 ml sterile distilled water and shaking for 2 minutes. after settling down for 10 min, serial dilutions of samples up to 10-4 dilution were performed. aliquot (1.0 ml) of dilution was inoculated into a petri dish containing modified bushnell-haas medium (bhm with agar). plates were incubated at 30°c for 48 hour; the formation colonies were then counted using digital colony counter device [20, 21] . 2.6.3 total hydrocarbons analysis by extraction method twenty-five gram of soil sample was taken from each tanks and blended with an equal amount of anhydrous sodium sulfate (na2so4). the mixture was placed in a whitman cellulose extraction thimble. the diesel remaining in this sample was extracted with 250 ml of dichloromethane (dcm) for two hours at a rate of 4 cycles/ hour using the soxhlet system[12]. the amount of residual diesel was determined by weight to quantify the amount of degraded diesel over time as follows: weight of residual diesel = weight of baker containingextracted diesel � weight of empty beaker … (1) weight of diesel degraded � ������ �� �� �!"#$ !�� �$ %&''' (����� �� ��$ #)*$� /&''' …(2) noor mohsen jabbar al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 4856 (2018) 51 3. results and discussion 3.1 physical and chemical properties of the soil the results of the soil characterization are presented in table 1. the basic ph of the soil sample 7.4 was within the ph range preferred for biological treatment. the soil contained a low percentage of organic matter 1.2%. the nutrient level in the soil was 51mg nitrogen /kg, 9.2 mg phosphate /kg, and 153 mg potassium/kg. soil texture is the primary determinant of water holding capacity. the higher the percentage of clay and silt was the greater the soil's ability to retain water and nutrients. the small particles of clay and silt have a larger surface area than large sand particles. this large surface area allows more water to be trapped. table 1, physical and chemical properties of the used soil 3.2 ex-situ experiment bioremediation (bio piles) biopile system was used to simulate bioremediation treatments through 35 days' period. two stainless steel tanks, one tank containing an amended soil: (contaminated soil with the addition of nutrients and bacterial inoculum), and the second tank was prepared for unamended soil as a control. among the main advantages associated with the use of the biopile system are the following: possibility control of system conditions (ph, temperature, ventilation and moisture content) and continuous monitoring. this provides optimal conditions for treatment and contributes to support of bacterial activity, which results in reduced processing time [22]. soil contaminated with diesel initially was contained 2140 mg /kg at zero days for both amended soil and unamended soil (control). the reduction of total petroleum hydrocarbons (tphs) was rapid within the first 7 days for amended soil and reached 1524 mg/kg when compared with that of the control soil 2000 mg /kg. at the end of treatment period, the reduction of tphs reached to 520 mg /kg for amended soil while reached to 1430 mg /kg for the control as shown in table 2. table 2, bioremediation of a soil contaminated with diesel during 35 days. as apparent from the results, the addition of mixed bacterial culture and nutrients has an advantageous effect on the bioremediation process. biostimulation accelerated tphs degradation because it plays an important role in supplementing nutrient constantly. it is important to add nutrients especially nitrogen source because nitrogen is a key building block of proteins and nucleic acids [21]. moreover, the addition of mixed bacterial culture represents the actual behavior of microorganisms in the environment contaminated with hydrocarbons. since in nature, the bioremediation process depends on the cooperative metabolic activities of organisms [23].the result agrees with those of (shabir et al., 2008) [21] , who found that the biodegradation rate of kerosene-contaminated soil was significantly enhanced by the addition of inorganic amendments along with the addition of mixed bacterial culture through 6weeks and reached to 65 %. the biodegradation rate in the biopile systems increased with time. after the first 7 days of remediation, the degradation rate of amended soil was 28%, while from the 14 day to the 28 day the degradation rate falls in the range 41.3% to 43.9 %. this is because the low molecular weight compounds were degraded extensively during the first week of treatment, while higher molecular weight compounds were partially degraded [24] . usually, all types of bacteria oxidize compounds with low molecular weight more readily. among the hydrocarbons, aliphatic compounds are expected to be more efficiently degraded. also, between branched and straight chain alkanes, time (days) total petroleum hydrocarbons (mg/kg soil) amended soil unamended soil (control) 0th day 2140 2140 7th. day 1524 2000 14th day 1256 1800 21th day 1228 1650 28th day 1200 1545 35th day 520 1430 characteristics values nutrients concentration (mg/kg soil) total nitrogen (mg n/ kg) 51 phosphate (mg p/ kg) 9.2 potassium (mg k/ kg) 153 soil texture 12% sand, 20% clay, 68% silt silty clay soil caco3 22.3 % soil ph 7.4 water holding capacity 16.85 % noor mohsen jabbar al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 4856 (2018) 52 bacteria favors degrading straight chain hydrocarbons [25] . at the end of remediation period (after 35 days), diesel-contaminated soil which amended with (mixed bacterial culture and nutrient) showed the highest degradation rate which reached to 75% while for unamended soil (control) the degradation rate reached to 38 %. the percentage of remaining diesel through remediation period showed in figures 3 and 4. fig. 3. percentage of remaining diesel through remediation time in amended soil. fig. 4. percentage of remaining diesel through remediation time in unamended soil (control). 3.3 evaluation changes in soil properties the variation in ph of soil contaminated with diesel can be attributed to metabolic processes. however, the ph range observed in this study still falls within the ph range suitable for microbial growth indicating that these isolates showed optimal growth in the ph range from 7.2 to 6.8. riskuwa and ijah reported that the growth of most microorganisms is usually greatest within a ph range of 6 to 8 [26]. the moisture content is an important factor and was measured to ensure that the air which was injected through the perforated pipes of bio pile system did not dry the soil and thus determining the bacterial growth. there was little change in soil moisture content of the biopiles over time. biological processing helps to maintain moisture within the allowable level because microorganisms during the metabolism of hydrocarbons produce water [19]. the ph and moisture content data of the polluted soil agree with earlier work by umar et al. who studied biodegradation of waste lubricating oil polluted soil [20]. moreover, temperature does not appear to have a greater effect on biodegradation, as biodegradation is found to occur in soil with moderate temperatures. the results of ph, moisture content and temperature were listed in table 3 and table 4. table 3, ph, moisture content, and temperature of amended soil table 4, ph, moisture content, and temperature of unamended soil 3.4 the bacterial counting a bacterial count was conducted for soil samples that were contaminated with diesel. it seems that soil bacteria were adapted to this oil level because they have shown high numbers of bacteria. for amended soil during the bioremediation period, the diesel-utilizing bacteria increased progressively from 3.1x105 cfu/g in the first week to1.20 x106 cfu/g in the fourth week and then decreased to 1.04 x106 cfu/g in the fifth week. the highest populations of dieselutilizing bacteria were 1.20 x106 cfu/g at the fourth week. bacteria utilizing diesel, in the beginning, were stimulated by simple times (days) ph value moisture content % temperature 0c 0th day 7.2 61.6 29.4 7th. day 7.3 68.3 37.6 14th day 7.3 55 36.4 21th day 7.3 56.6 33.3 28th day 7.3 53.3 32.9 35th day 7.1 65 33.1 times (days) ph value moisture content % temperature 0c 0th day 7.12 50 31.3 7th. day 6.9 50 29.9 14th day 6.8 65 30.8 21th day 6.8 60 32.3 28th day 6.8 73.3 31.8 35th day 6.8 61.6 29.8 noor mohsen jabbar al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 4856 (2018) 53 hydrocarbon sources (straight chain hydrocarbons) which caused a good percentage of degradation. as those components reduced, the mixed bacterial cultures had to utilize the more resistant hydrocarbons (aromatic hydrocarbons) [27]. it is probable that biodegradation of higher molecular weight hydrocarbons may create toxic intermediates that can prohibit the diesel-utilizing bacteria. the numbers of diesel-utilizing bacteria in soil samples amended with nutrients were higher compared to counts for unamended soil. this could be attributed to the presence of considerable quantities of nitrogen and phosphorous, two necessary nutrients for bacterial biodegradation activities [28]. the use of microorganisms that already have been adapted to hydrocarbons and increase their abundance helped to reach to the best bioaugmentation approach. diesel degradation was most related to the number of microorganisms degrading diesel. with the increased number of bacteria and the addition of nutrients, this way reduces the cleaning time considerably [4] . low bacterial counts and low contaminants levels can indicate that biodegradation were successful and that the bacteria are declining off because the contamination (food source) is decreasing. for unamended soil, the population of diesel-utilizing bacteria was range from 1.6x104 cfu/g to 3.5x104 cfu/g. changes in the counts of dieselutilizing bacteria during the 35-day of bioremediation study are represented in figures 5 and 6. these results matched with obiakalaije and makinde who studied the biostimulation effect on the degradation of crude oil-contaminated soil. the number of hydrocarbon degrading bacteria was increased from 2.51x105 to 1.74x106 cfu/ g [21] . fig. 5. changes in counting of diesel-utilizing bacteria for amended soil. fig. 6. changes in counting of diesel-utilizing bacteria for unamended soil (control). 4. conclusion the present study showed that the ex-situ bioremediation (bio piling) of diesel-polluted soil performed under aerobic conditions has shown to be an effective remediation method for hydrocarbons contaminated soils. the addition of nutrients to the soil contaminated with diesel stimulated the microbial population and showed an increase in degradation rates, especially during the early stages of degradation. an overall 75 % of the total petroleum hydrocarbons were removed from 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(2008). “biodegradation of waste-lubricating petroleum oil in a tropical alfisol as mediated by animal droppings”. bioresource technology , 99 , pp. 59–65. )2018( 48-56، صفحة 3د، العد14دجلة الخوارزمي الهندسية المجلم نور محسن جبار 56 biopileيولوجية للتربة الملوثة بالديزل باستخدام منظومة االمعالجة الب ***عالء كريم محمد **أستبرق حسن كاظم *نور محسن جبار *،***قسم الهندسة الكيميائية االحيائية/ كلية الهندسة الخوارزمي/ جامعة بغداد **دائرة معالجة المخلفات/ وزارة التعليم العالي والبحث العلمي noormuhcin89@gmail.com :البريد االلكتروني* demaestabriq1@gmail.com :البريد االلكتروني** alaa_univ@yahoo.com :البريد االلكتوني*** الخالصة بيئية خطيرة. ومن الطرق الواعدة تو التي تسببت في مشاكال (الديزل) معالجة التربة الملوثة بالمركبات النفطيةركزت هذه الدراسة على تخدام النشاط و األكثر فعالية لمعالجة التربة الملوثة بالنفط هي المعالجة البيولوجية بل هي الخيار الذي يوفر إمكانية تدمير الملوثات الضارة باس من أجل معالجة سريعة خارج الموقع و .bio pilingفحص قدرة الخليط البكتيري لمعالجة التربة الملوثة بالديزل في منظومة البيولوجي. تم ً كيلوغرام ٢٥على نطاق تجريبي ( biopilesوقد تم إنشاء منظومتين bio piling. للتربة الملوثة بالديزل تم اختيار منظومة من التربة لكل ا التربة الملوثة مع إضافة : (ملغم / كغم من الهيدروكربونات النفطية. التربة المعدلة ٢١٤٠منهما) و يحتويان على التربة الملوثة بما يقرب من توفير الظروف التي ٪ من نشارة الخشب، ثم زودت بالمغذيات الالزمة وتُسقى يومياً ل١٫٥المغذيات واللقاح البكتيري) حيث تخلط التربة مع عنصر سيطرة (التربة الملوثة بدون إضافة). ُجهز كال النظامين بوصفها تعزز نمو الكائنات الحية الدقيقة. تم تحضير التربة غير المعدلة ٪ من ٧٥الة يوما. تم إز ٣٥ مدةباألوكسجين لتوفير الظروف الهوائية،و تم الحضن في درجة حرارة الجو وُسحبت العينات اسبوعياً خالل الدراسة الى أن تجربة المعالجة خلصت .الدراسة مدة٪ من تربة السيطرة في نهاية ٣٨إجمالي الهيدروكربونات البترولية من التربة المعدلة و بالديزل. البيولوجية خارج الموقع هي اإلجراء المفضل،وهي اقتصادية وصديقة للبيئة، وبالتالي تمثل خيارا جيدا لمعالجة التربة الملوثة دينا al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 7, no. 4, pp 7687 (2011) effect of mixed corrosion inhibitors in cooling water system dina raheem department of engineering of medical instrument/ college of electronic and electrical technique email: dinarrhh78@yahoo.com (received 7 february 2011; accepted 28 september 2011) abstract the effect of mixed corrosion inhibitors in cooling system was evaluated by using carbon steel specimens and weight loss analysis. the carbon steel specimens immersed in mixture of sodium phosphate (na2 hpo4) used as corrosion inhibitor and sodium glocunate (c6 h11 nao7) as a scale dispersant at different concentrations (20,40, 60, 80 ppm) and at different temperature (25,50,75 and 100)ºc for (1-5) days. the corrosion inhibitors efficiency was calculated by using uninhibited and inhibited water to give 98.1%. the result of these investigations indicate that the corrosion rate decreases with the increase the corrosion inhibitors concentration at 80 ppm and at 100ºc for 5 days, (i.e, corrosion rate= 0.014gmd). keywords: corrosion in cooling tower, carbon steel corrosion, corrosion inhibitor of cooling tower. 1. introduction the term “corrosion” (in a cooling water system) is defined as the electrochemical deterioration of a metal that is in contact with cooling water. corrosion occurs when an electric current flows from one part of the metal (anode) through the water (electrolyte) to another part of the metal (cathode). corrosion takes place at the anode only. the cathode is the driving force of the corrosion action, as shown in the equation; metal → metal ions + electrons → + + …(1) this process degrades the metal, reduces its strength, thickness, and in some extreme cases, creates pits and then holes in the material. at some point in the corrosion process , the metal can no longer do its job as a system component. corrosion, in general, and pitting corrosion, in particular, must be guarded against in order to ensure the long term integrity of the cooling system.[1] in the corrosion of iron the reaction may proceed by a single step oxidation fe into ferric ion : fe → fe+3 + 3e …(2) in practice, a two-step process occurs in which iron is first oxidized to ferrous ion depending on the anode potential, fe → fe+2 + 2e …(3) and then is oxidized into ferric ion fe2+ → fe+3 + e …(4) the reactions above take place at the anode and must be balanced by other reduction processes that occur at the cathode. for example: o2 (gas) + 4h+ 4e→ 2h2o …(5) o2 (gas) + h2o + 4e→4oh …(6) the formation of ohat the cathode causes the ph here to be higher than in the bulk solution. eventually, ion migration of oh occurs, towards the anode, which promotes the formation of ferric hydroxide fe+3 + 3oh→ fe(oh)3 …(7) fe(oh)3 appears in the form of reddish brown colloid. this ferric hydroxide may react further in the presence of ferrous ions to produce fe3o4 [2]. mailto:dinarrhh78@yahoo.com dina raheem al-khwarizmi engineering journal, vol. 7, no. 4, pp 8697(2011) 77 the primary objectives of cooling water treatment are to maintain the operating efficiency of the cooling water system and to protect the equipment that contacts the cooling water. these objectives are accomplished by controlling or minimizing deposition, corrosion, and microbiological growth on the cooling water equipment. the deposits that occur in cooling water systems are usually divided into two categories: scale and fouling. the presence of either type of deposit in the heat exchangers or in the film fill can interfere with heat transfer, thereby reducing the efficiency of operation. deposits can also promote under-deposit corrosion. scale is formed from minerals, formerly dissolved in water, that were deposited from the water onto heat transfer surfaces or in-flow water lines. as water is evaporated in a cooling tower, the concentration of dissolved solids becomes greater until the solubility of a particular scale-causing mineral salt is exceeded. when this situation occurs in an untreated cooling water system, the scale will form on any surface in contact with the water, especially on heat transfer surfaces. the most common scaling minerals are calcium carbonate(caco3), calcium phosphate(capo4), calcium sulfate(caso4), and silica, usually in that order. formation of magnesium silicate scale is also possible under certain conditions. most other salts, including silica, are more soluble in hot water than in cold water; however, most calcium and magnesium salts, including calcium phosphate and calcium carbonate, are more soluble in cold water than in hot water. this is called “reverse solubility.” the water temperature will increase as recirculating water passes through the cooling system. as a result, calcium and magnesium scales may form anywhere in the system, but most likely on heated surfaces such as heat exchangers or surface condensers. silica will form in areas having the lowest water temperature, such as in the cooling tower fill. the principle factors responsible for scale formation are: 1. as alkalinity increases, calcium carbonatethe most common scale constituent in cooling systems decreases in solubility and deposits. 2. the mechanism for scale formation is the insitu crystallization of sparingly soluble salts as the result of elevated temperatures and/or low flow velocity. most salts become more soluble as temperature increases, however, some salts, such as calcium carbonate, become less soluble as temperature increases. therefore they often cause deposits at higher temperatures. 3. high tds water will have greater potential for scale formation. [4] the water is used in cooling systems as a heat transfer medium and frequently also as the final point to reject heat into the atmosphere by evaporating inside cooling towers. depending on the quality of available fresh water supply, waterside problems develop in cooling water systems from: scaling, corrosion ,dirt and dust accumulation and biological growth . any of these problems or more usually a combination of them result in costly unscheduled downtime, reduced capacity, increased water usage, high operation and maintenance costs, expensive parts replacements, and acid cleaning operations which reduce the life of the cooling system. selection of water treatment program for a specific system depends on: 1. system design, including system capacity, cooling tower type, basin depth, materials of construction, flow rates, heat transfer rates, temperature drop and associated accessories 2. water, including makeup water composition / quality, availability of pre-treatment and assumed cycle of concentration 3. contaminants, including process leaks and airborne debris 4. wastewater discharge restrictions 5. surrounding environment and air quality the critical parameters for cooling water are: conductivity, total dissolved solids (tds), hardness, ph, alkalinity and saturation index. conductivity is a measure of the ability of water to conduct electrical current and it indicates the amount of the dissolved solids (tds) in water. pure distilled water will have a very low conductivity (low minerals) and sea water will have a high conductivity (high minerals). dissolved solids present no problem with respect to the cooling capacity of water, since the evaporation rate of seawater, which has 30,000ppm total dissolved solids, is only 1% less than that of distilled water. the problem with dissolved solids is that many of the chemical compounds and elements in the water will combine to form highly insoluble mineral deposits on the heat transfer surfaces generally referred to as “scale”. the scale stubbornly dina raheem al-khwarizmi engineering journal, vol. 7, no. 4, pp 8697(2011) 78 sticks to the surfaces, gradually builds up and begins to interfere with pipe drainage, heat transfer and water pressure. ph: is a measure of how acidic/basic water is. the range goes from 0 14, with 7 being neutral. phs of less than 7 indicate acidity, whereas a ph of greater than 7 indicates a base. ph is reported in "logarithmic units," like the richter scale, which measures earthquakes. in general, when ph points to acidic environment, the chances for corrosion increase and when ph points to alkaline environment, the chances for scale formation increase. alkalinity: the ph values above 7 signify alkalinity. at ph values less than 8.3, most of the alkalinity in the water is in the bicarbonate form, and scale formation is normally not a problem. however, when the ph rises above 8.3, the alkalinity converts from the bicarbonate to the carbonate and the scale will start to form. hardness: the amount of dissolved calcium and magnesium in water determines its "hardness." the total hardness is then broken down into two categories: a. the carbonate or temporary hardness b.the non-carbonate or permanent hardness hardness particularly the temporary hardness is the most common and is responsible for the deposition of calcium carbonate scale in pipes and equipment. technically any bivalent metal ion such as iron, manganese or tin would constitute hardness, but calcium and magnesium are the two most prevalent forms. saturation index: the saturation index of a water or langlier saturation index (lsi) is a measure of the stability of the water with respect to scale formation. when lsi readings are positive they tend to be scale forming, and when they are negative they tend to be corrosive. normally readings within 1.0 unit from zero are considereds table [5, 6]. in cooling water systems, two basic techniques are used to provide corrosion protection to the metals that the water contacts: use of chemical corrosion inhibitors, and raising the ph of the cooling water. most military cooling water systems contain components fabricated primarily of copper alloy and mild steel. galvanized steel is present in galvanized cooling towers and stainless steel may be present in piping. as the cooling water ph is increased (ideally to within the range of 8.0 to 9.5. corrosion inhibitors are chemicals, which inhibit or reduce the corrosion rate of the steel or metallic surfaces. corrosion is an electrochemical phenomenon, which occurs due to anodic and/or cathodic. reactions. generally, the anodic reaction is the metal ion oxidation, and the cathodic reaction is the hydrogen ion reduction. therefore, the corrosion analysis and the corrosion inhibitors used to control the anodic reactions are classified as anodic corrosion inhibitor and the cathodic reactions are called as cathodic inhibitors. anodic inhibitors form a protective film coating on the anodic metal (where the metal is lost) and thus directly control corrosion by preventing the reaction that results in corrosion. any unprotected areas will corrode at a much faster rate than the protected areas, a factor that could result in pitting or localized attack of the unprotected areas. cathodic inhibitors form a protective film coating of the cathodic metal (where metal is not lost) and thus indirectly prevent corrosion by interfering with the current flow required for the electrochemical reaction to proceed between the cathodic and anodic metals. the corrosion reaction rate is governed by the size and type of the cathode relative to the anode. even when cathodic areas are not completely covered by the protective film, corrosion will occur, but usually more slowly and uniformly than when using anodic inhibitors alone. the occurrence of localized corrosion or pitting attack is greatly reduced. [6] the criteria for the selection of corrosion inhibitors are shown in table (1). the principal strategy for a cooling system corrosion protection program is to ensure protection of the metal in the heat exchanger (metal that is the thinnest metal in the system). the secondary goal is to provide protection from corrosion of the mild steel piping. when galvanized steel cooling towers are part of the cooling system, specialized corrosion inhibitors are the best control method. galvanized steel is corroded at ph levels above 9.0 and below 6.0. effective corrosion control requires maintaining appropriate ph levels, plus adding maintenance dosages of chemical corrosion inhibitors. chemical corrosion inhibitors form a protective film or barrier on the cooling system metal surfaces that have been cleaned prior to adding an initial high dosage of inhibitor. the initial high dosage of inhibitor passivates (protects) the metal. the appropriate dosage of corrosion inhibitor must be maintained dina raheem al-khwarizmi engineering journal, vol. 7, no. 4, pp 8697(2011) 79 continuously in the cooling water to ensure continuing protection. the examples of various passivation and maintenance dosage levels of corrosion inhibitors are shown in table (2) [7, 8] in order to prevent corrosion on galvanized steel cooling towers and associated pipes, formation of a non-porous surface layer of zinc carbonate is one of the effective methods. the formation of zinc carbonate layer is called passivation, which is accomplished by controlling ph during initial operation of the cooling tower. control of the cooling water ph in the range of 7 to 8 for 45 to 60 days usually allows passivation of galvanized surfaces to occur. in addition to ph control, operation and moderate hardness levels of 100 to 300ppm as caco and alkalinity levels of 100 to 300ppm as caco will promote passivation. the chemical cleaning and passivation formulation apply when the water system ph is 7.5 to 8.5 and adjust ph as required. formulation limitations may require adding separate components to keep things in solution. other formulations may be used: *orthophosphate or hexametaphosphate as (po4): 60 ppm * polyacrylate (active): 20 ppm * tolyltrizol (active): 10 ppm * soduim gluconate: 50 ppm * pluronic l-61 (active)(non ionic surfactant with antifoam: 400 ppm * phosphate scale inhibitor: 50 ppm . [9] table 1, criteria for corrosion inhibitor selection. corrosion inhibitor metal steel copper aluminum ph range (ideal) cathodic inhibitor polyphosphate excellent attacks attacks 6.5-8.5 zinc salts excellent none none 6.5-8.5 polysilicate excellent excellent excellent 7.5-10.0 molybdate good fair fair 7.5-10.0 anodic inhibitor orthophosphate good attacks attacks 6.5-8.5 orthosilicate good good good 7.5-10.0 . table 2, guide lines for passivation film formation and subsequent maintenance. corrosion inhibitor dosage (ppm) initial maintenance film formation time (days) cathodic inhibitor polyphosphate 40-60 as po4 10-20 as po4 5-6 zinc salts 10-20 as zn 3-5 as zn 5-6 polysilicate 40-60 as sio2 10-20 as sio2 10-12 molybdate 40-60 as mo 5-20 as mo 10-12 anodic inhibitor orthoophosohate 40-60 as po4 15-20 as po4 5-6 orthosilicate 40-60 as sio2 10-15 as sio2 10-12 copper corrosion inhibitor tolyltrizole 10-20 as tta 1-2 as tta 5-6 dina raheem al-khwarizmi engineering journal, vol. 7, no. 4, pp 8697(2011) 80 in general, other types of corrosion inhibitors are: mixed inhibitor: is composes of two or three types of inhibitor and majority of the proprietary corrosion inhibitor formula falls into this category. adsorption inhibitor: protective absorbed film is formed over the entire metal surface if adsorption inhibitor is used. the film helps to protect electrochemical reactions between metal and aqueous ions. some of the organic compounds are suitable to act as adsorption inhibitors [10]. 2. experimental procedure a lab rotary test was used in this investigation, the hot plate and stirrer (jenway 1000) were used and a 500 ml of beaker capacity was filled with mixture of corrosion inhibitors and specimen immersed for (1-5) days. the carbon steel specimen materials used in this investigation has the chemical composition which done in the al doura refinery by spectrometer ultima 2000 as shown in table (3): the surface of rectangular carbon steel alloy specimens which has the dimensions (10 x 3 x 0.2cm), (9 x 2 x 0.25 cm) were abraded by using emery paper of different grade numbers (220, 320, 400, 600), after abrasion the surfaces were cleaned with running tap water , followed by acetone rinse for 5 minutes and were dried in discator. different concentration of corrosion inhibitor were prepared, (20, 40, 60 and 80 ppm) mixture of na2 hpo4 and c6 h11 nao7 . after specimen׳s preparations, weighing the specimen and record w1, the specimen was clamped and immersed in a mixture of corrosion inhibitors at 20 ppm concentration , (i.e. the ratio= = 1010 ) using hot plate stirrer at medium velocity and at temperature 25°c, after 1day the immersion specimen, was removed and cleaned by washing it with running tap water and brushing it with bristle brush . then the specimens were immersed in benzene for 5 minutes to ensure removal of corrosion products from metal surface. the specimens were immersed in ethanol were dried in discator, then weights represented as w2. the procedure by using (40, 60 and 80 ppm) concentration and immersion for 2, 3 and 5 days at (50,75 and 100°c) temperature as shown in fig.(1) and fig.(2) table 3, the chemical composition for carbon steel fe si mn cr ni mo cu co al c s hb total elements % 74.2 2.2 9.0 2.2 2.7 3.5 1.1 2.5 1.3 1.2 0.1 300 100 fig.1. carbon steel specimen immersed in mixture of sodium phosphate and sodium gluconate. fig. 2. carbon steel specimen immersed in mixture of corrosion inhibitor on hot plate and stirrer at meduim velocity . 7 dina raheem al-khwarizmi engineering journal, vol. 7, no. 4, pp 8697(2011) 81 the efficiency of mixture corrosion inhibitors and scales dispersant (sodium phosphate and sodium glocunate) were calculated ,by using make up water(raw water) without corrosion inhibitor then calculated the corrosion rate for (1,2,3 and 5) days with corrosion inhibitor as shown in fig. (3), and analyze make up water and an inhibited water chemically. fig . 3. carbon steel specimen immersed in makeup water. 3. results and discussion 3.1. sodium phosphate effect the effect of corrosion inhibitor of sodium phosphate indicates that the film of iron phosphate (fe2 (po4 )2 ) produced to protect the surface of the specimen to passivate them and prevent the corrosion .as shown in the eq. 2na2hpo4 + 3fe +2h2o → fe3 (po4) 2 + 4naoh + h2 …(8) the results indicate that when the specimen immersed in the mixture of corrosion inhibitor for 5 days at a concentration of 30-40 ppm, this gave low value of corrosion rate than the immersion for 1 day. the relation was linear, this mean that the corrosion rate decrease with increasing the concentration and the time , as shown in table (4) and fig. (4). table 4, corrosion rate of carbon steel in mixture of sodium phosphate and sodium gluconate at different concentration and 25 °c temperature . test no. time /day conc. in ppm weight/w1 in gram weight/w2 in gram ∆w surface area (cm) *c.r. in gmd 1 1 20 47.1500 47.1516 0.0016 0.00652 0.24 2 1 40 47.1500 47.1514 0.0014 0.00652 0.21 3 1 60 47.1400 47.1412 0.0012 0.00652 0.18 4 1 80 47.1400 47.1411 0.0011 0.00652 0.16 5 2 20 47.1500 47.152 0.002 0.00652 0.15 6 2 40 47.1500 47.1519 0.0019 0.00652 0.14 7 2 60 47.2999 47.301 0.0011 0.00415 0.13 8 2 80 47.2999 47.3008 0.0009 0.00415 0.10 9 3 20 47.1500 47.1519 0.0019 0.00652 0.097 10 3 40 47.1400 47.1418 0.0018 0.00652 0.092 11 3 60 47.1400 47.1411 0.0011 0.00415 0.088 12 3 80 47.2999 47.3007 0.0008 0.00415 0.064 13 5 20 47.1423 47.1439 0.0016 0.00652 0.049 14 5 40 47.1400 47.1411 0.0011 0.00652 0.033 15 5 60 47.3300 47.3305 0.0005 0.00415 0.024 16 5 80 47.3300 47.3303 0.0003 0.00415 0.018 2 dina raheem al-khwarizmi engineering journal, vol. 7, no. 4, pp 8697(2011) 82 fig. 4. effect of concentration of mixture inhibitor on corrosion rate. 3.2. sodium glocunate effect the effect of sodium glocunate as scale dispersant indicates that the total dissolved solids (t.d.s.) will be decreased from 3000 ppm and to 300 ppm then minimize the electrochemical reaction under the deposit and tubes failed. their effect as sequestering agent forming water solution complexes with calcium in alkaline media and with iron in near neutral solutions is shown in the equation: 2c6h11nao7 + caco3 +h2o → ca(c6h11o7)2 + nahco3 + naoh ...(9) the concentration at 30-40 ppm of sodium glocunate indicates that the corrosion rate decreases for 5 days of immersion as shown in table (4) and fig.(4) . 3.3. time effect the corrosion rate decreases with increasing time at constant concentration according to the equation of corrosion rate. time and longer protective layer of mixture will prevent and decrease the corrosion rate as shown in fig.(5). = ∆ ( ) ( )× ( ) [11] . fig. 5. effect of time on corrosion rate with different conc. of mixture inhibitor. 0 0.05 0.1 0.15 0.2 0.25 0.3 20 40 60 80 c . r . i n gm d concentration in ppm 1 day 2 days 3 days 5 days 0 0.05 0.1 0.15 0.2 0.25 0.3 1 2 3 4 5 c . r . i n gm d time in days 20 ppm 40 ppm 60 ppm 80 ppm dina raheem al-khwarizmi engineering journal, vol. 7, no. 4, pp 8697(2011) 83 3.4. temperature effect the corrosion rate increased at temp. (25,50 and 75) °c for 1and 2 days because temp. increasing caused low passivity of corrosion inhibitors at 100 °c, the temp. effect will be less on the corrosion rate at 3 and 5 days because of the passivation film that will reduce heat transfer on the metal surface as shown in table(5) and fig.(6). table 5, corrosion rate of carbon steel in mixture of sodium phosphate and sodium gluconate at 80 ppm concentration and at different temperature. test no. time /day temp. in °c weight/w1 in gram weight/w2 in gram ∆w surface area (cm) *c.r. in gmd 1 1 25 47.1500 47.1511 0.0011 0.00652 0.16 2 1 50 47.1498 47.1415 0.0017 0.00652 0.27 3 1 75 47.1432 47.1445 0.0022 0.00652 0.34 4 1 100 47.1400 47.1414 0.0014 0.00652 0.23 5 2 25 47.2999 47.3008 0.0009 0.00415 0.10 6 2 50 47.2998 47.3014 0.0016 0.00415 0.20 7 2 75 47.1500 47.1539 0.0039 0.00652 0.30 8 2 100 47.1500 47.1515 0.0015 0.00652 0.20 9 3 25 47.2999 47.3007 0.0008 0.00415 0.064 10 3 50 47.1400 47.1417 0.0017 0.00652 0.09 11 3 75 47.1400 47.1429 0.0029 0.00652 0.15 12 3 100 47.3300 47.3312 0.0012 0.00415 0.12 13 5 25 47.3300 47.3303 0.0003 0.00415 0.018 14 5 50 47.1500 47.1506 0.0006 0.00652 0.02 15 5 75 47.1400 47.1409 0.0009 0.00652 0.028 16 5 100 47.2999 47.3002 0.000029 0.00415 0.014 fig. 6. effect of temp. on corrosion rate at different times and at 80 ppm of mixture corrosion inhibitors concentration. 2 dina raheem al-khwarizmi engineering journal, vol. 7, no. 4, pp 8697(2011) 84 3.5. mixture efficiency the efficiency of mixture of sodium phosphate and sodium glocunate were (83.3, 87.5, 93.8 and 98.1%) at 80 ppm concentration, and at 1,2,3,5 days respectively, the corrosion rate of makeup water (raw water) were calculated for 1, 2, 3 and 5 days to compare the efficiency of the mixture by applying the equation of the efficiency, where the efficiency increases with time as shown in the table (6) and table (7). = – × 100% [12] when carbon steel is immersed in raw water, the anodic reaction is: fe → fe2+ + 2e− …(10) the cathodic reaction is: o2 + 2h2o + 4e− → 4oh− …(11) table 6, the corrosion rate of makeup water. time/day w1( gram) w2(gram) ∆w surface area cm2 c. r. ( gmd) 1 47.1423 47.1486 0.0063 0.00652 0.96 2 47.1414 47.1558 0.0144 0.00652 1.1 3 47.3200 47.3402 0.0202 0.00415 1.5 5 47.1435 47.2184 0.0749 0.00652 2.3 table 7, efficiency of mixture of sodium phosphate and sodium glocunate at 80 ppm. then after 5 days the uniform corrosion will occur while the protective layer of fe3 (po4 ) 2 formed on the surface of carbon steel specimen as shown in fig.(7) and fig.(8) respectively, the chemical analysis of cooling water (inhibited water) were obtained from al-doura refinery explain the values of alkalinity and ph increased because of mixture effect as shown in table (8). table 8, chemical analysis for make up(raw water) and cooling tower water. water parameter make up water cooling water alkalinity as ppm 144 374 total hardness as ppm 250 544 t.d.s as ppm 397 1370 ph 7.4 8.27 conductivity in mmhoms 663 1712 sodium phosphate as ppm 80 sodium gluconate as ppm 80 time (day) c.r.(uninhibited water) c.r.(inhibited water) efficiency% 1 0.96 0.16 83.3 2 1.1 0.15 87.5 3 1.5 0.092 93.8 5 2.3 0.042 98.1 dina raheem al-khwarizmi engineering journal, vol. 7, no. 4, pp 8697(2011) 85 fig. 7.uniform corrosion on carbon steel specimen. fig. 8.protective layer on carbon steel specimen. 4. conclusion from experimental results using corrosion inhibitor mixture (sodium phosphate as corrosion inhibitor and sodium glocunate as scale dispersant)in cooling tower at 20,40,60 and 80 ppm concentration ,one concludes that at 80 ppm concentration of mixture and at temp. above 75 °c and for 5 days is more efficiently in cooling tower treatment to format passive film and decrease the corrosion rate. 5. recommendation some recommendations are suggested to improve the future work because of microbiological growth in cooling tower such as algae, fugi and bacteria, then: 1the treatment with biocides by adding to sample of cooling water : a. oxidizing biocides such as( chlorine, bromine, chlorine dioxide, ozone, silver peroxide, etc) b. non-oxidizing biocides :organic chemical compounds . c. biodispersants : surfactant. 2study the effect of the microbiological growth in cooling tower and measure the corrosion rate of carbon steel with effect of microbiological growth. 3calculate the corrosion rate of carbon steel immersed in corrosion inhibitor ,scale dispersant and biodispersant mixing . 6. references [1] p.r. roberge, handbook of corrosion engineering, mcgrawhill, 1999. [2] r. wiston, uhlig’s, corrosion handbook, 2nd edition, page 173, john wiley and sons inc., 2000. [3] mario machado , "cooling tower technologies and management – water minimization", australian industry group,2010 [4] john kubis, "power station zero discharge ,cooling tower", nace international ,no.08396,2010. [5] rl martin, b.a. alink, t.g. braga and a.j. mcmahon, r. "weare,environmentally acceptable water soluble corrosion inhibitors", corrosion 95, paper no.36, nace, 1995. [6] a. bhatia, "cooling water problems and solution",web siteinfo@cedengineering.com , 2010. [7] dr. e.moses road," inorganic phosphates based corrosion inhibitors for industrial cooling water system, ion exchange india ltd. 2010. [8] irvin cotton,”analyst spring 2003 – cooling system – chemical treatment “ . [9] donald l. basham, p.e, "industrial water treatment operation and maintenance", by united facilities criteria (ufc), http://dod.wbdg.org/. 25 may 2005. mailto:siteinfo@cedengineering.com http://dod.wbdg.org/ dina raheem al-khwarizmi engineering journal, vol. 7, no. 4, pp 8697(2011) 86 [10] c.c.nathan “corrosion inhibitors” national association and corrosion engineer, vol.21,pp.120, no.3, june, (1983). [11] annual book of astm standard "corrosivity of water in the absence of heat transfer (weight loss method)",designation :d 2688,feb.15,1983. [12] c.c.nathan, "studies on the inhibition by amines of the corrosion of iron by solutions of high acidity ", national association of corrosion engineer ,vol.9 ,p.199 ,1948. )2011( 86 -97 ، صفحة3، العدد 7مجلة الخوارزمي الھندسیة المجلد دینا رحیم 87 خزان التبرید تأثیر خلیط مثبطات التآكل في منظومة دینا رحیم التقنیات الكھربائیة وااللكترونیةكلیة /قسم االجھزة الطبیة .comdinarrhh78@yahoo:البرید االلكتروني الخالصة غمرت نماذج الكربون ستیل في خلیط من . كربون ستیل وطریقة فقدان الوزن خلیط مثبطات التآكل في منظومة التبرید باستعمال معدن تأثیر تم تقییم جزء بالملیون ) ٢٠,٤٠,٦٠,٨٠(كمشتت تكلسات وبتراكیز مختلفة c6h11nao7 ومتأكل وكلوكنیت الصودیكمثبط na2hpo4فوسفات الصودیوم تم حساب كفاءة المثبطات باستخدام ماء بدون إضافات ومع اإلضافات وكانت كفاءة . أیام )٥-١(م و لمدة ◦) ٢٥,٥٠,٧٥,١٠٠(,مختلفة وعند درجة حرارة ودرجة جزء بالملیون ٨٠تركیز نتائج البحث تبین أن معدل التآكل یقل مع زیادة تركیز خلیط مثبط التآكل عند .جزء بالملیون ٨٠عند تركیز %98.1الخلیط . یوم. ٢م/غم ٠.٠١٤=أي إن معدل التآكل , أیام ٥ولمدة م ◦١٠٠حرارة ابتهال ‘وفاء‘ اورهان al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 85 -93 (2013) effects of different types of fillers on dry wear characteristics of carbon-epoxy composite ibtihal a. mahmood* wafa a. soud** orhan s. abdullah*** *,**,***department of machine and equipments engineering/ university of technology *email: ibtihalnamie@yahoo.com **email: wafaabd_92@yahoo.com ***email: orhan_sabah@yahoo.com (received 17 march 2013; accepted 22 may 2013) abstract experimental investigations had been done in this research to demonstrate the effect of carbon fiber and ceramic fillers contents on the tribological behaviour of (15% volume fraction) carbon-epoxy composite system under varying volume fraction, load, time and sliding distance. the wear resistance were investigated according to astm g9905standard using pin on disc machine to present the composite tribological behaviour. the influence of three ceramic fillers, granite, perlite and calcium carbonate (caco3), on the wear of the carbon fabric reinforced epoxy composites under dry sliding conditions has been investigated. the effect of variants in volume fraction, applied load, time and sliding distance on the wear behaviour of polymer composites is studied by measuring the weight changes . in the experiments with wear test pin having flat face in contact with hardening rotating steel disc, sliding speed, time and loads in the range of 200 rpm, 300–900s and 40–60 n respectively was used. it is observed that the wear resistance increase with the increasing of reinforcement material volume fraction while, the wear rate increases with increasing of applied load, time and sliding distance. the results showed that the filler of granite perlite and caco3 as filler materials in carbon epoxy composites will increase the wear resistance of the composite greatly than carbon fiber fillers epoxy composite only and granite filled ce composite exhibited the maximum wear resistance. keywords: carbon-epoxy composite, ceramic fillers, sliding wear. 1. introduction with our continuing quest for lighter and stronger composites, the demand for new types of composite materials is increasing. in recent years various composite materials have been used extensively in aircraft structures, space vehicles, automobiles, sporting goods, electronic packaging to medical equipment, and many consumer products[1]. the main advantage of composite materials is the potential for a high ratio of stiffness to weight, corrosion resistance, high fatigue strength etc.[2] epoxy resin (ep) is a thermoset resin with good thermal and environmental stability, high strength and wear resistance. this combination of properties permits the application of ep in polymer-based heavy duty sliding bearings. for these purposes, ep usually is compounded with reinforcements like glass or carbon fibers and ceramic .mineral oxides and inorganic fillers [3]. the use of fillers in polymeric composites helps to improve tensile and compressive strengths, tribological characteristics, toughness (including abrasion), dimensional stability, thermal stability, and other properties. in addition to the higher mechanical strength obtained due to the addition of fillers in polymeric composites, there is cost reduction in terms of consumption of resin material[4]. in order to obtain perfect friction and wear properties many researchers modified polymers using different fillers [5-12]. briscoe et al.[5] reported that the wear rate of high density polyethylene mailto:ibtihalnamie@yahoo.com mailto:wafaabd_92@yahoo.com mailto:orhan_sabah@yahoo.com ibtihal a. mahmood al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 8593 (2013) 86 (hdpe) was reduced with the addition of inorganic fillers, such as cuo and pb3o4. tanaka[6] concluded that the wear rate of polytetrofluroethylene (ptfe) was reduced when filled with zro2 and tio2. bahadur et al.[7-9] found that the compounds of copper such as cuo and cus were very effective in reducing the wear rate of peek, ptfe, nylon and hdpe. kishore et.al.[10] studied the influence of sliding velocity and load on the friction and wear behaviour of ge composite, filled with either rubber or oxide particles, and reported that the wear loss increased with increase in load/speed. solid lubricants such as graphite and mos2 [11,12] when added to polymers proved to be effective in reducing the coefficient of friction and wear rate of composites. the objective of this work is to investigate the wear properties of carbon fiber epoxy composite at different volume fraction and different ceramic particulate at 15% gf chopped filled epoxy matrix composites sliding against a hardened steel counter face. as a comparison, the wear properties of plain c-e were also evaluated under identical test conditions. this work helps in understanding the function of different fillers in c-e composites. 2. experimental details 2.1. materials three particulate reinforcing materials (granite) ,(perlite) and (caco3) prepared from german company with grain size (10 µm) and volume fraction (1%,2,5%,4 %, and 5% vol.) were used here to reinforce the epoxy-carbon composite. the matrix system (epoxy resin quick mast 105 +and hardener quick mast 105) was commercially obtained from (dcp) jordan company. the details of epoxy resin illustrated in table (1). the main reinforcement used was chopped carbon fiber used in this research with length (12mm) and diameter (10-14µm) produced by (grace cemfiber company). the properties of carbon fiber as shown in table (2). the properties of (granite), (perlite) and (caco3) particles shown in tables (3), (4) and (5) respectively, [used from sheet supplied]. 2.2. specimens preparation all specimens in this study were manufactured by hand layup technique. the mould that was used is made of glass with dimension of (200, 150, 10) mm as shown in figure (1). the mould must clean and covered the inside walls of the mould with vaseline to prevent the adhesion between the mould and polymeric material. the polymeric material is present by mixing the epoxy resin with the hardener in (3:1) ratio at room temperature, the mixing was very slow, using glass rod for (15min) until it becomes homogenous, chopped carbon fibers are reinforced in epoxy resin to prepare the composite group b1. no particulate filler is used in this composite. the volume fraction of carbon fiber in composite is kept at 2.5, 5, 7.5, 10, 12.5, 15 vf % for samples, the other composite groups (b2, b3 and b4) with particulate fillers 1, 2.5, 4, 5 vf% of granite, perlite and caco3 added to 15%vf carbon fiber respectively the fillers are mixed thoroughly in epoxy resin before the carbon fibers are reinforced in the matrix body and continuously mixing until it becomes homogenous, the mixing is completed after (2min), then the mixture is poured in the mould from one side only to eliminate the entrapment of air, when the solidification process for all moulds is completed after 24 hours, the casts are released from the moulds. the mould is cut in to a standard specimen dimensions according to astm g99-05 standard as shown in figure (2). 3. sliding wear testing the wear test was performed by using pin-ondick test instrument shown in the figure (3). the wear rate calculated according to eq.(1) at different volume fraction, loading, sliding time and sliding distance.the disc is made of a tool steel material with hardness (385 hv), which has a rotating radius of (90 mm) and a rotating speed of (200 r.p.m.). all tests were conducted at room temperature. wear tests were conducted with loads ranging from (40-60 n) and sliding distance range (942-1507.2m) and sliding time ranging from (300-900s). the initial weight of the specimens was measured using sensitive balance weight with an accuracy of (10-4 g). after the end of testing the specimens were removed, cleaned with acetone, dried and weighed to determine the weight loss due to wear. the differences in weight measured before and after tests gives wear of the composite specimen. the following relation is used to investigate the wear volume loss which is: wear rate (volume) (cm3/m) = …(1) ibtihal a. mahmood al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 8593 (2013) 87 where: w1: weight before testing (g), w2: weight after testing (g), ρ:density (g/cm3) and s: sliding distance (m) calculated from the formula: s=2πrnt …(2) where: r: the distance from the center of the sample to the center of disc in meter, n: disc rotational speed in r.p.m, and t:time of testing in(min). table 1, physical and mechanical properties of epoxy resin[13]. flexural strength (mpa) specific heat (j/kg.k) tensile strength gpa density g/cm3 flexural strength (mpa) 13 1050 20-25 1.004 13 table 2, physical and mechanical properties of carbon fiber[13]. young's modulus gpa density g/cm3 tensile strength gpa poisson's ratio thermal conductivity w/m.k 230 1.8 2.4 0.20 105 table 3, physical and mechanical properties of granite particles. young's modulus gpa density g/cm3 possin's ratio diameter appearance 52 2.75 0.3 ≥ 10µm grey powder table 4, physical and mechanical properties of perlite particles. young's modulus gpa densit g/cm3 possin's ratio diameter appearance 46.51 2.04 0.296 ≥ 10µm white powder table 5, physical and mechanical properties of caco3 particles. young's modulus gpa density g/cm3 diameter appearance 72.36 2.83 ≥ 10µm white powder ibtihal a. mahmood al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 8593 (2013) 88 fig. 1. the shape of the mould. fig. 2. standard wear test specimen[14]. fig . 3. schematic of pin-on-disc wear testing machine. ibtihal a. mahmood al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 8593 (2013) 89 4. result and discussion 4.1. wear test wear test was investigated for specimens prepared from epoxy before and after adding the reinforcement materials. wear test type pin on disc carried out for these specimens various graphs are plotted and presented in figures (4 to 11). for different percentage of reinforcement under different test conditions. (volume fraction, load, time and sliding distance. 4.1.1. effect of volume fraction the wear resistance of group (b1) samples with different volume fraction of carbon fiber shown in figure (4). when compared with the matrix material an increase represents in of 55.92% in wear resistance with the adding of 15% carbon fiber. with the adding of granite, perlite or caco3 particles filler to 15% carbon fiber further increase in wear resistance of group (b2, b3 and b4) as shown in figure (5). at comparison to 15% glass fiber an increase represents in of 62.33%, 54.28% and 46.36% in wear resistance respectively. fig. 4. effect of volume fraction on wear rate of carbon fiber. fig. 5. effect of volume fraction on wear rate of granite, perlite, caco3 particles with 15% carbon fiber. 4.1.2. effect of applied load the influence of different normal loads on the wear rate of the un-reinforced and reinforced composites at constant parameters such as rotating disc speed 200 rpm, time 15min and sliding distance 1507.2m. the wear rate of all composite samples increases with increased normal load. this is because at higher load, the frictional thrust increases, which results in increased deboning and fracture. a similar effect of different normal load on volumetric wear rate has been observed by cirino et.al.[15]. as shown in figure (6). the wear rate of composite material with (5%, 10%, 15%) carbon fiber. an increase represents by (25%, 39%, 46%) respectively in wear resistance can be recognized when compared to the matrix material, in the case of carbon epoxy composite and verma et. al. [16] for crp composite. it has also been observed that the wear rate decreases with addition of carbon fiber up to 15vol% under all testing condition. with the adding of 2.5% granite, perlite or caco3 powder with 15% carbon fiber further increase in wear resistance as shown in figure (7). th an increase recorded can be represented by (42.4%, 37.5%, and 29.6%) respectively in wear resistance when compared to reinforced carbon fibers only. thus it can be conclude, addition of the ceramic particles granite, perlite and calcium carbonate. the wear rate values are directly proportional with normal load, this fact can be seen clearly when we compare the figures (6) to (7), and the reason of this proportional due to the increasing of the friction force which increases, when the normal load increases, because of the fraction area increasing. this lead to the increasing of loss weight, and finally the increasing of wear rate. fig. 6. effect of load on the wear rate of carbon fiber. ibtihal a. mahmood al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 8593 (2013) 90 fig. 7. effect of load on wear rate of granite, perlite, caco3 with15% carbon fiber. 4.1.3. effect of sliding time figure (8) shows the behaviour of wear with sliding time of the epoxy matrix specimen and reinforced by different carbon fiber volume fraction (5%, 10%, 15%) respectively, it can be seen that the wear rate of the composite pin increases with the increase of the period of sliding time similar to the case of the increasing the load, and the worst wear rate when unreinforced epoxy also it can be seen the wear rate degree when increase in volume fraction of carbon fiber and the great wear resistance at 15% carbon fiber volume fraction. at comparison with the matrix material wear resistances an increase represents by (26.7%, 43.25%, 56%). fig. 8. effect of time on wear rate for carbon fiber. from figure (9) shows, the relationship between the sliding time and the wear volume loss of the composite pin reinforced by (15%) carbon fiber volume fraction at different ceramic particles granite, perlite and caco3 for (volume fraction 2.5%). increase in wear resistance as shown in figure (9). when compared to 15% carbon fiber an increase represents by (44.16%, 39%, 33%) respectively in wear resistance. it can be seen in these figures, at the beginning of the sliding time the values of wear rates for all samples under tests are high values, this behavior may be due to the separation of asperities from the sample surface. fig. 9. effect of time on wear rate of granite, perlite, caco3 powder with 15% carbon fiber. 4.1.4. effect of sliding distance the assessments of wear rate with different sliding distance under the testing conditions as shown in fig (10and11). figures(10) have been plotted to explain the variation of wear rate with sliding distance at normal load 50 n. the wear resistance of composite material with (5%,10%,15%) carbon fiber as shown in figure (10). an increase represents in of (26.7%, 43.35%, 56%) respectively in wear resistance when compared to the matrix material. it has been observed that the wear rate increases with increasing sliding distance for all the samples. it is also observed that the 15vol% carbon fiber reinforced composite shows a minimum wear rate under all testing conditions. this again reveals that the addition of carbon fiber can improve the wear resistance of composite. fig. 10. effect of sliding distance on wear rate of carbon fiber. ibtihal a. mahmood al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 8593 (2013) 91 as figure (11) show with the adding of 2.5% granite, perlite or caco3 particles to 15% carbon fiber further increase in wear resistance as shown in figure(11). at comparison to 15% carbon fiber an increase represents in of (44.15, 39%, and 33%) respectively in wear resistance. the assessments of wear rate with different sliding , figures-have been plotted to explain the variation of wear rate with sliding distance at normal load 50n. it has been observed that the wear rate increase with increasing of sliding distance for all the samples. it is also observed that the 15 vol% cf reinforced composite shows a minimum wear rate under all testing conditions. this again reveals that the addition of fiber can improve the wear resistance capacity of epoxy. fig. 11. effect of sliding distance on wear rate of granite, perlite, caco3 particles with 15% carbon fiber. table 6, list of abbreviations and symbols abbreviations and symbols meaning units ep epoxy resin hdpe high density polyethylene ptfe polytetroflouroethylene peek polyetherether ketone c-e carbon-epoxy astm american society of testing and materials w1 weight before testing g w2 weight after testing g s sliding distance m ρ density g/cm3 5. conclusions the primary conclusions are as follows: 1. the wear volume loss of the reinforced epoxy specimen increases as the load, time and sliding distance increases. 2. the wear resistance of the composite system increase with the increasing of reinforcement material for all the specimen. 3. the addition of carbon fiber as a reinforcement material leads to increase the wear resistance of epoxy composite more than unreinforced epoxy. 4. 4-the adding of ceramic fillers to carbon epoxy composite leads to increase the wear resistance more than carbonepoxy composite without ceramic fillers. 5. granite filler added to carbon-epoxy composite show better wear resistance than perlite and caco3 particles. 6. the highest wear resistance is that of the composite with 15% carbon fiber +5% granite particles, which is 83.4 % higher than that of the matrix material. 6. references [1] pedro v., jorge f., antonio m. and rui l., "tribological behavior of epoxy based composites for rapid tooling",wear 260, pp. 30-39, 2006. 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[10] kishore, sampathkumaran, p., seetharamu, s., vynatheya, s., murali, a., kumar, r.k., “sem observations of the effect of velocity and load on the slide wear characteristics glass-fabricepoxy composites with different fillers”. wear, vol. 237, pp. 20-27, 2000. [11] kishore, sampathkumaran, p., seetharamu. s., thomas, p., janardhana, m. a., “study on the effect of the type and content of filler in epoxy-glass composite system on the friction and wear characteristics.” wear vol. 259, pp. 634-641, 2005. [12] wang, j., gu, m., songhao, ge, s., “the role of the influence of mos2 on the tribological properties of carbon fiber reinforced nylon 1010 composites.” wear, vol. 255, pp. 774779, 2003. [13] d. hull and t.w. clyne, "an introduction to composite materials", second edition, cambridge university press, london, 1996. [14] astm g99–05 (reapproved 2010), standard test method for wear testing with a pin-on-disk apparatus, american society for testing and materials, edition 2010. [15] cirino, m., pipes, r.b. and friedrich, k., “the abrasive wear behavior of continuous fiber polymer composites”, j. mater. sci., 22: pp. 2481–2492, 1987. [16] verma, a. p. and sharma, p. c., “abrasive wear behaviour of grp composite”, the journal of the institute of engineers (india), pt mc2,vol.72, pp. 124, 19 )2013( 85 93، صفحة 2، العدد9مجلة الخوارزمي الھندسیة المجلد ابتھال عبد الرزاق محمود 93 كاربون -لالیبوكسي تأثیر الحشوات السیرامیكیة على خواص البلى للمواد المتراكبة ***اورھان صباح عبداهللا **وفاء عبد سعود *ابتھال عبدالرزاق محمود الجامعة التكنولوجیة /ھندسة المكائن والمعداتقسم ***،**،* ibtihalnamie@yahoo.com: البرید االلكتروني* wafaabd_92@yahoo.com :البرید االلكتروني ** orhan_sabah@yahoo.com :البرید االلكتروني *** الخالصة الك اربون بالی اف المق واة لراتنج ات االیبوكس ي خ واص الترایبولوجی ة عل ى ال تأثیر الیاف الكاربون والحشوات السیرامیكیة دراسة تمت البحث ھذا في 60–40 باستعمال جھاز المسمار مع القرص الدوار وعند احمال astm g99-05ة مقاومة البلیان وفقا للمواصفةتم دراس. %15 حجمي كسر وعند عملیا n ومسافات انزالقm 942-1507.2 900–300 وازمان مختلفةs مقاومة البلیان تزداد مع زیادة الكسر الحجمي لمواد ءاالختبارات لوحظ بانوبعد اجرا ویك ون مع دل البلی ان للعین ات الغی ر مدعم ة اعل ى بكثی ر م ن ، ط والزمن ومسافة االنزالقلالحمل المس بزیادة بصورة عامة یزداد البلى معدل التدعیم بینما وان مقاومة البلیان للعینات المحتویة مع الحشوات السیرامیكیة المختلفة الیاف كاربون %15بنسبة العینات المدعمة بالیاف الكاربون فقط والعینات المدعمة ربونیة فقط وان مقاومة البلیان لمجموعة العینات المقواة بالیاف كاربون مع كرانیت بلغت على حشوات سیرامیكیة تكون اعلى من العینات المدعمة بالیاف كا نستنتج من ذالك اضافة الحشوات السیرامیكیة مع الیاف الكاربون یحسن بشكل . اعلى قیمة لھا تلیھا ألعینات المدعمة بالبرالیت ثم عینات كاربونات الكالسیوم .كبیر من مقاومة البلیان mailto:ibtihalnamie@yahoo.com mailto:wafaabd_92@yahoo.com mailto:orhan_sabah@yahoo.com فرح محمد ومصطفى al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 9, no. 1, p.p. 47-59 (2013) mathematical modeling of glucose regulation system in term of perturbed coefficients mustaffa mohammed basil* farah mohammed ridha masood** *,**department of biomedical engineering/ al-khwarizmi college of engineering/ university of baghdad *email:alfatlaw@msu.edu **email:fmr82000@yahoo.com (received 6 february 2012; accepted 19 september 2012) abstract in this research a recent developed practical modeling technique is applied for the glucose regulation system identification. by using this technique a set of mathematical models is obtained instead of single one to compensate for the loss of information caused by the optimization technique in curve fitting algorithms, the diversity of members inside the single set is interpreted in term of restricted range of its parameters, also a diagnosis criteria is developed for detecting any disorder in the glucose regulation system by investigating the influence of variation of the parameters on the response of the system, this technique is applied in this research practically for 20 cases with association of national center for diabetes / al mustanseryia university. keywords: glucose regulation system, compartmental modeling, perturbed coefficients. 1. introduction in the last decades, there was an increasing demand to obtain a quantitative technique to study physiological systems, for the purposes of diagnosis, therapy, and research. one of the most important techniques that was developed is the compartmental modeling, which is a description to dynamic behavior of physiological systems in term of differential equations based on mass balance equations; these differential equations represent the relationship between exogenous or endogenous material as inputs and the resulted states of physiological system as outputs. the compartmental model was first derived to describe the kinetics of isotopic tracer, science then it was extensively used to deal with wide spectrum of problems in this field, and this can be tracked in [1, 2, 3, and 4]. compartmental model can be obtained by lumping materials with same characteristics into collections, this will reduce the physiological system into compartments, which can be defined as well mixed and kinetically homogenous materials, and interconnections between them, these interconnections represents the flux of influence from one compartment to another. the recent development in system identification technique has been posed in compartmental modeling. according to system identification theory problem of physiological modeling can be solved through two tasks, first the system specification should be featured by a mathematical model derived from the mass balance equations, secondly the parameters of this mathematical model should be calculated by using the experimental data. the main challenge in the above process is the inherent nonlinearity in physiological system, which is obvious in experimental data; on the other hand a linearized model for these systems exhibits a high degree of uncertainty because of the information loss in the process of linearization. a new algorithm is presented in [5], this algorithm solved this problem by representing nonlinear system by a linear model with perturbed coefficients, and this results a family of models which can cover all aspects of nonlinearity. mailto:email:alfatlaw@msu.edu mailto:email:fmr82000@yahoo.com mustaffa mohammed basil al-khwarizmi engineering journal, vol. 9, no.1, p.p. 47-59 (2013) 48 diabetes is one of the most threatening diseases that human face. it is considered one of the major reasons for kidney failure, blindness and limbs amputation. the growth of population and the resulted degradation in health care system, limitation of normal life activity because of the advance in technology, and obesity are the main reasons for the worldwide spreading of this disease, so the importance of formulating a robust mathematical model for the glucose regulation system has been grown over the past decades. this model is derived with the aid of experiments which track the behavior of the glucose concentration after applying an intentioned perturbation in it by specific oral or intravenous dose of glucose. 2. theory the problem of glucose system regulation in term of perturbed coefficients can be characterized generally as follows: for any experimental set of data obtained from tracking blood glucose concentration after an oral dosage of glucose for fasting person [5]: ( ) i = 1,2, … , n. n: no. of data. let ( )be the nominal function that represents these data, such that ( ) = + +. . + …(1) : number of compartments. , : constant coef icients. there is family of mathematical models: ( ) ∶= ( ): ∈ , , ∈ , , : upper bound of th coef icient. , : lower bound of th coef icient. for = 1,2, … , . the above problem can be solved by an algorithm of three steps: 1. system specification. 2. nominal parameters estimation. 3. perturbation ranges calculations. 2.1. system specification [6] consider a general physiological system with n compartments as seen in fig (1): fig. 1. general compartmental model. ̇ = − − + …(2) where: = , = : i exogenous input. : output lux of i compartment. : transferring lux from compartment to . : transferring lux from compartment to . by assuming that this model represents the linearized version of physiological system, then all transferring flux functions can be substituted by linear functions of compartments masses as follows: = …(3) = …(4) = …(5) by substituting eq. (3) to (5) into eq. (2): ̇ = ∑ −∑ − + …(6) after rearranging eq. (6): ̇ = ∑ − ∑ + + …(7) by assuming that: = − ∑ + …(8) after substituting eq. (8) in eq. (7), yields: ̇ = ∑ + …(9) mustaffa mohammed basil al-khwarizmi engineering journal, vol. 9, no.1, p.p. 47-59 (2013) 49 the state space representation for n compartments according to the above set of first order differential equations is: ̇ = + …(10) where: = [ … ] = ⋯ ⋮ ⋱ ⋮ ⋯ = [ … ] since the experimental data consider the compartments concentration, the nominal output equation is: = …(11) where: = [ … ] where: v : volume of i compartment. the solution for above state space system provides a qualitative understanding for the dynamic specifications of physiological system, so for the following state transition matrix: ( ) = ℒ [ − ] …(12) the time course of compartment concentration as a response to impulse exogenous input can be obtained by: ( ) = [ ( ) (0) + ( ) ] …(13) where: ∶ amplitude of the impulse exogenous input . eq. (13) results: ( ) = 2.2. nominal parameters estimation [7] for this task, the least square fit algorithm is used, a brief description for this algorithm, that is the process of curve fitting for data set that contains a significant amount of noise and this can be done by minimizing the following function: ( , , … , , ) = ∑ [ ( )− ( )] …(14) where the weight of experimental data. optimal set of parameters can be obtained by solving the following equation: = 0 = 1,2, … , …(15) the above notation implies that we already have mathematical form of ( ), which was derived previously. 2.3. perturbation ranges calculations [5,8,9] since least square fit is an optimization technique, then the resulted function doesn't give a full representation to all experimental data, to overcome this weakness in the mathematical model, all unrepresented information will be modeled as a weighted perturbation range for each parameter, so each parameter will be limited by upper and lower bound, this problem can be formulated as follows: ∈ , ∈ , where: = + …(16) = − …(17) = + …(18) = − …(19) , : wights of perturbation. , : lower limits of perturbation. , : upper limits of perturbation. for = 1,2, … , . for mathematical convenience, weights will be represented as: ω = [ω ω ω … … … …ω ] × ω = [ω ω ω … … … …ω ] × while perturbations will be represented as: ̅ = [ … … … … ] × ̅ = [ … … … … ] × mustaffa mohammed basil al-khwarizmi engineering journal, vol. 9, no.1, p.p. 47-59 (2013) 50 a) weights selection the problem of finding appropriate weight is considered in this part. weight selection is extremely important for minimizing the family of models, by eliminating unnecessary members. each parameter in the nominal function has its particular weight, which is defined as the average value of deflections, which occur in nominal function at each time of experimental data, caused by small variation in that parameter. ∆ represents the error between nominal function and experimental data. ∆ = ( )− ( ) …(20) for = 1,2, … , . sensitivity of nominal function to particular parameter can be defined as: = ( ) …(21) = ( ) …(22) for = 1,2, … , . now the participation of each parameter in the error between the nominal function and experimental data can be calculated from: ∆ = ∆ ∗ …(23) ∆ = ∆ ∗ …(24) = ∑ + ∑ = ∑ + ∑ for = 1,2, … , . for = 1,2, … , . ∆ , ∆ : the de lection in the nominal function caused by variation in parameter or at each experimental data . for mathematical simplicity, matrix notation will be used in calculation of weights, so first we construct , and ∆ are constructed as follows: = ⋯ ⋮ ⋱ ⋮ ⋯ × = ⋯ ⋮ ⋱ ⋮ ⋯ × ∆ = [ ∆ ∆ … ∆ ∆ ] × the perturbation in nominal function which is de ined as: ∆ = [∆ ∆ ∆ … …∆ ] × ∆ = [∆ ∆ ∆ … …∆ ] × and can be calculated as follows: ∆ = ∆ ∗ …(25) ∆ = ∆ ∗ …(26) finally the weight of perturbation is: ω = ∗ ∆ …(27) = [ … … ] × ω = ∗ ∆ …(28) = [ … … ] × b) parameter interval identification in this part the range of parameter perturbation is calculated, and this can be done by solving the following equation for the variable & at each time of experimental data: ( ) = ( + ) ( ) +⋯+ ( + ) ( ) …(29) the solution of above n variables can be estimated according to the following: lets de ine the ℓ range of perturbation in ̅ ∶ ̅ = 0, ≠ ℓ ̂ ℓ, = ℓ …(30) ̅ = 0, ≠ ℓ ̂ℓ, = ℓ … (31) for = 1,2, … , . by substituting eq. (30)in(29), yields ∶ ( ) = +⋯+ ℓ ℓ + ( ℓ + ℓ ̂ℓ) ℓ + ℓ ℓ +⋯+ …(32) by substituting eq. (31)in(29), yields ∶ mustaffa mohammed basil al-khwarizmi engineering journal, vol. 9, no.1, p.p. 47-59 (2013) 51 ( ) = +⋯+ ℓ ℓ + ℓ ( ℓ ℓ ℓ) + ℓ ℓ + ⋯+ …(33) solving eq. (31) and (33) yields ̂ ℓ and ̂ ℓ, which represents the maximum deflection in ℓ parameter caused by the difference between experimental data and nominal function. the actual value of deflection can be calculated by using the following equation: ℓ = ̂ ℓ ∗ ℓ∑ ∑ …(34) ℓ = ̂ ℓ ∗ ℓ∑ ∑ …(35) for = 1,2, … , . now, for( ℓ = 1,2, … , ), we will have ∶ ̅ℓ = [ … … ] × ̅ℓ = [ … … ] × for upper and lower range of perturbation for parameters respectively = max { 0, } = min { 0, } = max { 0, } = min { 0, } 3. experimental results for oral glucose tolerance test in order to maintain glucose concentration in an adequate level, two hormones are functioning opposite to each other inside the human body, the first hormone is glucagon, which is produced by a pancreatic islets called alpha cells, the secreting of this hormone stimulate the liver to convert the stored glycogen into glucose and release it to the blood, on the other hand the second hormone which is called insulin, produced by a pancreatic islets called beta cells, this hormone assist in assimilation of the glucose. the best approach to obtain data for glucose regulation system modeling, is to observe time response of glucose utilization in blood, one of the ways to do that is the oral glucose tolerance test (ogtt), it is based on applying oral dosage of glucose, which can be modeled mathematically as impulse function, then the glucose concentration in blood with measuring is measured appropriate sampling rate. since only the blood glucose concentration will be taken in consideration, then one compartment can represent the system here, and the best function that can be fitted to the experimental data is: ( ) = …(36) in this research, ogtt test is carried out for a 20 person, in association with the national center for diabetes / al mustanseryia university. the results of the ogtt test base on 75 of oral glucose are exhibited in table(1). after substituting resulted values (for each case in the table above) in eq. (43), the result will be a family of mathematical models for each case. the family members are bounded by the following two boarder models: ( ) = …(37) ( ) = e …(38) < < where: ∶ upper limit of the family of models. : lower limit of the family of models. the above argument can be proved practically in fig. (2) to (21), which represent the time response of glucose regulation system for the 20 cases, in these figures, the dotted blue line represents the experimental data, while the upper red line represents the upper bound in eq. (37), the lower red line represents the lower bound in eq. (38), and the middle red line represents the nominal values in eq. (36). mustaffa mohammed basil al-khwarizmi engineering journal, vol. 9, no.1, p.p. 47-59 (2013) 52 table1, 4. discussions since the least square fit is an optimization technique, there is a certain level of information loss which can be useful in describing the dynamic of the system. in the control point of view the process of evaluating any system take into consideration two main characteristics, stability and performance. a. stability: the glucose regulation system with parametric uncertainty is stable if and only if all the members of this family of models are stable, this means that for stability: < 0 …(39) according to eq. (36), the stability mainly counts on the values of parameter , any negative value in its range, indicates a possibility of instability in the glucose regulation system. in the results in section 3, there are seven cases with such possibility which are cases 2, 3, 11, 15, 17, 19, and 20. if equal weights are assigned for the possibilities of the values of , the possibility of instability for glucose regulation system % for all cases which exhibit negative values of can be calculated according to the following equation: % = ∗ 100% …(40) table (2) shows the possibility of instability for all tested cases: no. 1 185.966 185.970 173.702 0.00550 0.0150 0.00260 2 168.084 168.086 164.000 0.00220 0.00430 -0.00210 3 167.437 170.000 167.436 0.00117 0.00214 -0.00022 4 188.748 196.000 188.746 0.00308 0.00658 0.00155 5 187.855 192.338 187.846 0.00517 0.0159 0.00235 6 168.276 173.000 168.2747 0.00480 0.00578 0.00367 7 180.478 180.479 180.000 0.00327 0.00448 0.000820 8 189.348 189.3486 185.978 0.000900 0.00155 0.000159 9 200.819 200.818 184.387 0.00421 0.00800 0.00328 10 164.346 164.3465 161.000 0.00460 0.00512 0.00389 11 150.763 168.000 150.7619 0.000793 0.00730 -0.000687 12 222.484 222.486 208.982 0.00776 0.0106 0.00457 13 152.920 154.5770 152.9182 0.00232 0.00494 0.00138 14 171.227 173.715 171.2226 0.00351 0.00794 0.00185 15 142.161 142.164 142.000 0.00340 0.00655 -0.00112 16 162.767 168.000 162.7656 0.00255 0.00770 0.000780 17 134.7700 137.000 134.7680 0.00187 0.00358 -0.000607 18 188.458 193.161 188.456 0.00425 2.7964 0.00269 19 150.430 155.5115 150.4245 0.00289 0.00922 -0.000391 20 176.8654 176.8686 168.7136 0.00214 0.00638 -0.002122 mustaffa mohammed basil al-khwarizmi engineering journal, vol. 9, no.1, p.p. 47-59 (2013) 53 table 2, b. performance: fast reaction to any sudden increase in blood glucose level is adopted in this research to evaluate the performance of the glucose regulation system, this means that the performance mainly depends on the decay rate . the normal results for the ogtt adopted by the national center for diabetes / al mustanseryia university mention in table (3). by using the recommended values in the above table and solving eq. (36) for the value of ′: ′ = − ′ ln ′ for > y′ …(41) where: : initial experimental value. ′: recommended decay rate for normality. so for normality: > ′ …(42) table (4) shows initial values of experimental glucose concentration, the recommended value for each tested case, the experimental value for the decay rate, and the status of each case according to the condition in eq. (42). case no. initial value ( ) recommended decay rate experimental decay rate status 1 174 0.001811774 0.0026 normal 2 164 0.001318533 -0.0021 abnormal 3 170 0.001617967 -0.00022 abnormal 4 196 0.002803935 0.00155 abnormal 5 196 0.002803935 0.00235 abnormal 6 173 0.001763743 0.00367 normal 7 180 0.002094287 0.00082 abnormal 8 186 0.002367535 0.000159 abnormal 9 190 0.002544847 0.00328 normal 10 161 0.001164683 0.00389 normal 11 168 0.001519346 -0.000687 abnormal 12 209 0.003339099 0.00457 normal 13 155 0.000848189 0.00138 normal 14 174 0.001811774 0.00185 normal 15 142 0.000118205 -0.00112 abnormal 16 168 0.001519346 0.00078 abnormal 17 137 0.001040165 -0.000607 abnormal 18 186 0.002367535 0.00269 normal 19 156 0.00090178 -0.000391 abnormal 20 170 0.001617967 -0.002122 abnormal mustaffa mohammed basil al-khwarizmi engineering journal, vol. 9, no.1, p.p. 47-59 (2013) 54 table 3, table 4, 5. conclusions in the control point of view the process of evaluating any system take into consideration two main characteristics, stability and performance, according to these two main points a new diagnosis criteria can be concluded from the results for detecting any disorder in glucose regulation system, based on the range of perturbation for parameters in its mathematical model. fig. 2. the time response of glucose -case (1). fig. 3. the time response of glucose -case (2). fig. 4. the time response of glucose -case (3). case no. % case no. % 1 0.00% 11 8.60% 2 32.81% 12 0.00% 3 9.32% 13 0.00% 4 0.00% 14 0.00% 5 0.00% 15 14.60% 6 0.00% 16 0.00% 7 0.00% 17 14.50% 8 0.00% 18 0.00% 9 0.00% 19 4.07% 10 0.00% 20 24.96% ′( ) ′( ) 60 <200 120 <140 mustaffa mohammed basil al-khwarizmi engineering journal, vol. 9, no.1, p.p. 47-59 (2013) 55 fig. 5. the time response of glucose -case (4). fig. 6.the time response of glucose -case (5). fig. 7. the time response of glucose -case (6). fig. 8. the time response of glucose -case (7). fig. 9. the time response of glucose -case (8). fig. 10. the time response of glucose -case (9). mustaffa mohammed basil al-khwarizmi engineering journal, vol. 9, no.1, p.p. 47-59 (2013) 56 fig. 11. the time response of glucose -case (10). fig. 12. the time response of glucose -case (11). fig. 13. the time response of glucose -case (12). fig. 14. the time response of glucose -case (13). fig. 15. the time response of glucose -case (14). fig. 16. the time response of glucose -case (15). mustaffa mohammed basil al-khwarizmi engineering journal, vol. 9, no.1, p.p. 47-59 (2013) 57 fig. 17. the time response of glucose -case (16). fig. 18. the time response of glucose -case (17). fig. 19. the time response of glucose -case (18). fig. 20. the time response of glucose -case (19). fig. 21. the time response of glucose -case (20). mustaffa mohammed basil al-khwarizmi engineering journal, vol. 9, no.1, p.p. 47-59 (2013) 58 6. references [1] carson,e.,r.,cobelli,c.,and finkelstien,l. "the mathematical modelling of metabolic and endocrine system". john wiley sons, new york. ( 1983). [2] godfrey, k.,. "compartmental models and their application". academicpress, london,( 1983). [3] jacquez, j.a.. "compartmental analysis in biology and medicine". 3rd ed., biomedware, ann arbor, mi,( 1996). [4] cobelli, c., foster, d.m., and toffolo, g. "tracer kinetics in biomedical research : from data to model". plenum publishing corp.,(2000). [5] basil, m., m., "system identification algorithm for systems with interval coefficients",under press. [6] bronzino, j., d., "the biomedial engineering handbook", ieee press, (2006). [7] kivsalaas, j., "numerical method in engineering", cambridge university press, (2010). [8] sanchez, r., s., "robust system theory and application", john wiley & sons (1998). [9] bhattacharyya, s., p., chapellat, h., and keel, l., h., "robust control parametric approach", prent ice ha ll (1995) . )2013(47-59 ، صفحة1، العدد9مجلة الخوارزمي الھندسیة المجلدمصطفى محمد باسل 59 النمذجة الریاضیة لمنظومة السیطرة على سكر الكلوكوز بصیغة المعامالت المتذبذبة **فرح محمد رضا مسعود* مصطفى محمد باسل جامعة بغداد /كلیة الھندسة الخوارزمي / قسم ھندسة الطب الحیاتي** ،* alfatlaw@msu.edu :البرید االلكتروني* fmr82000@yahoo.com :البرید االلكتروني** الخالصة باستخدام ھذه الطریقة ،في ھذا البحث تم استخدام طریقة مستحدثة للنمذجة بصورة عملیة في عملیة نمذجة منظومة السیطرة على تركیز السكر في الدم ریاضي سیتم الحصول على مجموعة من النماذج الریاضیة بدال من نموذج واحد لتعویض الخسارة فى المعلومات الناجمة عن عملیة استحصال اقرب نموذج ت في النموذج الریاضي بین قیمتین ھذا التنوع في النماذج الریاضیة داخل المنظومة الواحدة ناجم عن تغییر المعامال. یحاكي المنظومة بصورة مقربة ایضا في ھذا البحث تم تطویر طریقة تشخیصیة ریاضیة الكتشاف اي خلل في منظومة السیطرة على السكر في الدم من خالل مراقبة تاثیر ھذا ،محددتین لة بالتعاون مع المركز الوطني للسكري فى الجامعة و تم تطبیق ھذه الطریقة بصورة عملیة على عشرین حا. التغییر في المعامالت على استجابة المنظومة .المستنصریة mailto:alfatlaw@msu.edu mailto:fmr82000@yahoo.com <4d6963726f736f667420576f7264202d20d3e3edd120e6e3e5e4cf20e6c7e1cde3d2c920ddc7d1e6de312d203131> experimental study the effect of tool design on the mechanical properties of bobbin friction stir welded 6061-t6 aluminum alloy samir ali amin* mohannad yousif hanna** alhamza farooq mohamed*** *,**,*** department of mechanical engineering/ university of technology *email:alrabiee2002@yahoo.com ** email: mohannad_hanna@yahoo.com ***email: alhamza88f@yahoo.com (received 27 september 2017; accepted 30 january 2018) https://doi.org/10.22153/kej.2018.01.003 abstract bobbin friction stir welding (bfsw) is a variant of the conventional friction stir welding (cfsw); it can weld the upper and lower surface of the work-piece in the same pass. this technique involves the bonding of materials without melting. in this work, the influence of tool design on the mechanical properties of welding joints of 6061-t6 aluminum alloy with 6.25 mm thickness produced by fsw bobbin tools was investigated and the best bobbin tool design was determined. five different probe shapes (threaded straight cylindrical, straight cylindrical with 3 flat surfaces, straight cylindrical with 4 flat surfaces, threaded straight cylindrical with 3 flat surface and threaded straight cylindrical with 4 flat surfaces) with various dimensions of the tool (shoulders and pin) were used to create the welding joints. the direction of the welding process was perpendicular to the rolling direction for aluminum plates. tensile and bending tests were performed to select the right design of the bobbin tools, which gave superior mechanical properties of the welded zone. the tool of straight cylindrical with four flats, 8 mm probe and 24 mm shoulders diameter gave better tensile strength (193 mpa), elongation (6.1%), bending force (5.7 kn), and welding efficiency (65.4%) according to tensile strength. keywords: bobbin fsw, bobbin tool design, aa6061-t6, mechanical properties. 1. introduction friction stir welding (fsw) is a solid-state bonding process feigned in 1991, at the welding institute. fsw is a substitutional welding technique to conventional fusion welding. the joint is produced via a non-consumed refractory cylindrical rotating tool, mechanically passed through the material of the work-piece. the friction between wear-resistant tool and the substrate generates heat. because the frictional heat is generated, the stirred material is softened and mixed [1]. under the shoulder of the tool, the material flows are like the forging operation, whereas the flows of material surrounding the tool probe are similar to the extrusion operation [2]. this technique is used for joining aluminum alloys, although other materials are possible inclusive dissimilar materials. the welding technology, patented via thomas et al. [3], has been used to automotive, shipbuilding, and aerospace industries [4]. the usage of a bobbin friction stir welding (bfsw) tool, see figure (1), presented the capability to outdo of the limitations faced in the cfsw [5]. this technique uses a tool consisting of a probe and double shoulders. the tool shoulders contact with both the lower and upper substrate surface. it can be referred to that the aluminum alloy plates with higher thickness could be joined al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 14, no.3, september, (2018) p.p. 111 samir ali amin al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 111 (2018) 2 by friction stir welding process; nevertheless, the next information show why it’s eligible to also use the bfsw-tool for this intent. using double shoulders able to balance the down forces created via the tool with individual shoulders and so revokes the resulted axial down force. as well, the peril of root defect is basically removed with this type of tool design. due to the uniform heat input distribution, the bobbin fsw process exhibits good welded joints with lest distortions compared to the cfsw process. in addition, the bobbin friction stir welding technique could superfast the transverse speed and raise the efficiency of the welding process in substrate with thicker section [6]. fig. 1. schematic diagram of bfsw [4]. the design of a single shoulder tool (cfsw) has been focused by numerous researches, while the bobbin tool has had so less studies solicitude. t. neuman et al. [7] have reported that the tool with threaded cylindrical probe and the tool with threaded cylindrical probe having 3 flats enable to create satisfying welding outcomes, since there is no formed internal defect. the above tools were utilized to weld aa2024-t351 with 4 mm thickness. m. k. sued et al. [8] investigated the influence of probe geometry on the mechanical properties and microstructure development of 6082-t6 aluminum alloy joining by bfsw and developed a model relating the basic physics to the manufacturing process in fsw bobbin-tool. w. m. thomas et al. [9] notified complete permeation bfs welded joints, free of penetration shortage, and root flaws. for bobbin tool, two shoulders supply appropriate heat generation from both the surfaces of the substrate, and the inclusion of reactive forces within the tool itself denotes that compressive distortion (squashing) of the pin does not take place. to promote the swept soft material volume via a tapered probe; investigators exhorted 3 flat surfaces feature to be used on the probe. this tool geometry was applied to weld 12% chromium alloy steel 8 mm thick, and produced a successful good weld [10]. a tapered probe with three flats allows to reduce the diameter of the bottom shoulder that participates in lowering the bending moment and torque. a lot of other researchers studied the understanding of the influence of welding process parameters on the material flow characteristics, microstructure evolution and mechanical properties of the joint line welded by bfsw [11-15]. the aim of this paper is first to design and manufacture a new fixed type bobbin tool, to show the effect of changing the diameters of the pin and shoulders of this tool, and then select the best design of this bobbin tool depending on the mechanical properties (elongation, tensile strength and maximum bending force) and weld joint quality for aluminum alloy (6061-t6) welded by bobbin fsw. 2. experimental work 2.1 selection of material and specimens preparation in this work the base metal was aluminum alloy aa6061-t6, which is (al-mg-si) grade alloy of 6xxx series. the plate of aa6061-t6 was cut into the desired size (200 mm x 100 mm x 6.25 mm) via a power saw cutting machine, and the edge of the piece was ground to secure that there is no chasm exists between the two substrates that make the desired butt joint design. the chemical composition of the work-piece plate was obtained via a spectra device available in special institute for engineering industries (siei), as presented in table (1). the mechanical properties were performed for this plate in strength laboratory in mechanical engineering department, university of technology and are given in table (2). table 1, standard and actual chemical compositions of aluminum alloy 6061-t6 wt.% si fe cu mn mg cr zn ti ni al standard[16] 0.4-0.8 < 0.7 0.15-0.4 < 0.15 0.8-1.2 0.04-0.35 < 0.0.25 < 0.7 < 0.05 bal. actual 0.6 0.57 0.26 0.10 0.89 0.18 0.037 0.054 0.003 bal. element samir ali amin al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 111 (2018) 3 table 2, standard and actual mechanical properties of aluminum alloy 6061-t6 yield stress(mpa) ultimate tensile stress(mpa) elongation (%) standard value [16] ≥ 240 ≥ 290 ≥ 10 actual value 244.5 295 11.5 2.2 design and manufacturing of bobbin tools there are two significant domains of bobbin friction stir welding tool design: selection of tool material and geometry (features and dimensions). there are significant influences to the tool pending welding: high temperature, abrasive wear and dynamic influences. therefore, the good materials of the tool have the following characteristics: good wear resistance, high temperature strength, temper resistance and good toughness. in the fsw of aluminum alloys, the wear of the welding tool is not so much. tool materials like tool steel can be utilized for fsw [2]. hot-work tool steel (h13) is the most ordinarily utilized material, easy availability and machinability, wear resistance, thermal fatigue resistance, essentially for copper and aluminum [17]. the tools in this work were fabricated from a hot-work tool steel (h13). in order to select a best design, five various tools with probe profiles (threaded straight cylindrical pin, straight cylindrical with three flat surfaces, straight cylindrical with four flat surfaces, threaded straight cylindrical with three flat surfaces and threaded straight cylindrical with four flat surfaces) and flat shoulders with different diameters in all cases were utilized, see figure (2). the bobbin friction stir welding tools were fabricated by conventional lathe and milling machines. the tool heat treatment comprises heating the tool alloy to 1070°c about 30 min and then air cooling to room temperature, followed by two tempering steps at 550°c and 500°c, respectively. then, the tool was air cooled to room temperature in each step, resulting in a hardness about 49 hrc [18, 19]. all details of designed and fabricated bobbin tools are given in table (3), including pin diameter, flat side width, pitch of the thread, shoulder diameter, feature of shoulder surface and shoulders gap. 2.3 welding procedure the substrate has to be clamped rigidly at a predetermined location onto a fixing framework, see figure (3). bobbin welding is started by driving onto the edge of the work-piece and then the workpiece is moved against the pin. the experiments were completed using a one pass normal to the plate rolling direction (longitudinal). at first, slow travel speed till plastic deformation occurs, followed by acceleration of the welding speed to the required speed, and then the tool moves over the joint line at a constant travel speed. the material in front of the rotating tool probe is plastically distorted and stirred back to the trail edge of the tool pin in the welding [20]. the used welding parameters were selected according to the information from the previous research in this field and the practical expertise. these parameters are given in table (4). classic milling machine model (fu 251) was used to complete the welding process. fig. 2. a) threaded straight cylindrical with 4 flat surfaces, b) straight cylindrical with 4 flat surfaces, c) threaded straight cylindrical with 3 flat surfaces, d) straight cylindrical with 3 flat surfaces, e) threaded straight cylindrical pin. c d e a b samir ali amin al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 111 (2018) 4 table 3, bfsw tools (dimensions and features) description of the probe bfsw tool no. pin diameter (d) (mm) flat side width(mm) pitch of thread (mm) shoulder diameter (d)(mm) feature of shoulder gap of shoulders (mm) straight threaded cylindrical bt-1 10 _____ 1.5 20 (2d) flat 6.25 straight threaded cylindrical bt-2 10 _____ 1 20 (2d) flat 6.25 straight cylindrical + 3 flats bt-3 10 0.67 _____ 20 (2d) flat 6.25 straight cylindrical + 4 flats bt-4 10 0.67 _____ 20 (2d) flat 6.25 straight threaded cylindrical+ 3 flats bt-5 10 0.67 1 20 (2d) flat 6.25 straight threaded cylindrical+ 4 flats bt-6 10 0.67 1 20 (2d) flat 6.25 straight threaded cylindrical bt-7 8 _____ 1 16 (2d) flat 6.25 straight cylindrical + 3 flats bt-8 8 0.5 _____ 16 (2d) flat 6.25 straight cylindrical + 4 flats bt-9 8 0.5 _____ 16 (2d) flat 6.25 straight threaded cylindrical+ 3 flats bt-10 8 0.5 1 16 (2d) flat 6.25 straight threaded cylindrical+ 4 flats bt-11 8 0.5 1 16 (2d) flat 6.25 straight threaded cylindrical bt-12 12 _____ 1.5 24 (2d) flat 6.25 straight cylindrical + 3 flats bt-13 12 0.8 _____ 24 (2d) flat 6.25 straight cylindrical + 4 flats bt-14 12 0.8 _____ 24 (2d) flat 6.25 straight threaded cylindrical+ 3 flats bt-15 12 0.8 1.5 24 (2d) flat 6.25 straight threaded cylindrical+ 4 flats bt-16 12 0.8 1.5 24 (2d) flat 6.25 straight cylindrical + 4 flats bt-17 8 0.5 _____ 20 (2.5d) flat 6.25 straight cylindrical + 4 flats bt-18 10 0.67 _____ 25 (2.5d) flat 6.25 straight cylindrical + 4 flats bt-19 12 0.8 _____ 30 (2.5d) flat 6.25 straight cylindrical + 4 flats bt-20 8 0.5 _____ 24 (3d) flat 6.25 straight cylindrical + 4 flats bt-21 8 0.5 _____ 24 (3d) flat 6.4 straight cylindrical + 4 flats bt-22 8 0.5 _____ 24 (3d) flat 6.1 straight threaded cylindrical+ 3 flats bt-23 8 0.5 1 24 (3d) flat 6.25 samir ali amin al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 111 (2018) 5 fig. 3. fixing framework. table 4, used bobbin friction stir welding process parameters tool rotational speed (spindle speed) (rpm) 560 welding speed (travel speed) (mm/min) 80 dwell speed (mm/min) manual dwell time (s) 40 2.4 mechanical tests tensile test was done on specimens possessed in direction normal to the joint line to define the tensile properties of the joints for all welding experiments. the form and dimensions of the longitudinal tensile specimens according to the standard (astm-e8) are presented in figure (4.a). tensile experiments were done at 1 mm/min loading rate at room temperature using a computerized universal testing machine (hydraulic tunis olsen). then, the average value of three tested samples was taken for determining the elongation and ultimate tensile strength of each joint. three point bending test was done to obtain the maximum bending force of the joints. the form and dimensions of the longitudinal bending sample according to the standard (astm-e190) are presented in figure (4.b). the bending test was done at constant loading rate (5 mm/min) at room temperature by a universal testing machine (hydraulic laryee testing machine). fig. 4. a) tensile test specimen (all dimensions in mm) (astm-e8), b) bending test specimen (all dimensions in mm) (astm-e190m) . 3. experimental results and discussion 3.1 visual inspections the visual inspection consequences are presented in fig. 5. these exhibit the bottom and top of each joint. some of the welded joint had a good appearance, while other welds appeared various flaws, involving open tunnel/void, excessive flash, cutting effects and incomplete joining. 1) open tunnel and excessive flash (figures 5a and 5b): this phenomenon has not been discussed and identified its causes in the previous literature in large active area, but it can be explicated as follows. the distribution of vertical material flow was asymmetry that was evident in threaded cylindrical probe. this distribution had overflowing material on the upper substrate surface, and weld bead thinning on the lower surface. the probe threads might result much material motion toward the single surface. the potential of threaded profile potential resulting extravagant flux of vertical material has previously been specified [21]. the clockwise rotation of the tool, which is the state of present research, also the stationary vertical location of the bobbin tool prohibited the down movement of the tool. in this state, the threads existence on the probe draws up the work-piece. thus, the swept material from the retreating side faces the soft material of the advancing side, and a complicated blending type a samir ali amin al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 111 (2018) 6 engenders, see figure (6). the retreating side shown in figure (7a) is pushed vertically up toward the advancing side. therefore, the top site of the advancing side (figure 7b) is firstly filled. the smaller threads pitch will possess minimal helix angle, thus minimizing the transportation of vertical material and the flash defect, see figure (7). 2) cutting effect (figure 5c): in this state, the plates were softened and cut via the bobbin tool and no welding took place. this was occurred when the diameter of the pin was 12 mm (about twice thickness of substrate) bt (12-16). the reason of this case is that the amount of heat input was not enough. the amount of heat generated is not significant to produce a good mixing for soft material flow and occur a dynamic recrystallization compared to the volume of the material was stirred. for (bt-19) design, the welding was successful, because the diameter of the shoulders was bigger; this means the heat input was significant to produce free defect welding. 3) incomplete joints/voids/flash defect (figures 5d to 5g): with gap's variation, there are changes in the semblance of welding line. when the bobbin tool (bt-21) has a gap of 6.4 mm, which is higher than the upper allowable limit of plate thickness (6.25 mm) due to the difficulty in filling and coalescing the stir zone. another case was the tool (bt-22) having a gap of 6.1 mm. at the top surface, there was only a slight of flash, while at the bottom surface there was an excessive flash/ scraping and consequent decrease in thickness. several welding joints were unacceptable, because there were flash and voids in the joint line and the other joints were incomplete. these defects are not dependent only on the pin geometry (shape and dimension). other variables can cause these defects, e.g. bad tool fabrication, substrate condition (flatness variation), and support/clamp setting, see figure (8). also, the failed outcomes possess partnership to how explicate the acceptable welding joints. it is submitted that the sundry influences participate to acceptable welds. the stirred material needs to have horizontal and vertical flow; the flow movement produces by the tool features. thus, threads create vertical flow motion [21, 22] and flats produce horizontal movement [23]. hence, the tools (threaded cylindrical with 3/4 flats), which comprise these profiles, achieved properly. tools that own flats only, such as (straight cylindrical with 3/4 flats), are also capable to create sound welds. since the used plate here was not thick, it is suggested that the fit gap between the shoulders of the tool and substrate thickness equips with a vertical motion flow element of soft material. thus, whereas flat faces might not produce the movement of vertical flow, these features do not counter it [8]. fig. 5. a) open tunnel defect/ lower surface (bt-1), b) excessive flash defect/ upper surface (tb-1), c) cutting effect (bt14), d) void defect/ upper surface (bt-21), e) incomplete welding/ lower surface (bt-21), f) excessive flash defect/ lower surface (tb-22), few flash/ upper surface (tb-22) . c d e f g a b samir ali amin al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 111 (2018) 7 fig. 6. material motion around threaded probe. fig. 7. minimizing the flash defect (bt-2) . fig. 8. variation of flatness plate (bt-20) . fig. 9. a) upper surface, b) lower surface . 3.2 destructive inspections after implementing the welding experiments, the joints were visually tested and the welds with perfect surface appearance were selected and machined according to the standard test samples for the mechanical testing. mechanical tests were conducted to define the mechanical behavior of the weld zone and select the best probe design by the maximum welding efficiency in terms of tensile strength. tensile and bending tests were done, and the results have been classed according to the tool probe shape. the results are listed in table (5). from these results, the best bobbin tool design for the investigation condition (substrate type, thickness, and process settings) is (bt-20), which provides superior mechanical properties, see figure (9). since the spindle and welding speeds used in this work cannot be considered as optimum parameters, so the obtained results of the mechanical properties are not the maximum for this bobbin tool (bt-20) design. 3.3 effects of used bobbin tool design features and dimensions on weld quality the outcomes characterize specifically the functional effects, for example, the thread on tool probe. the following duty is to establish a systematic explication for the causality by tool shape and other parameters that cause weld quality influences. these are established on the interpretations (above) of the empirical clues compiled in this work, and informed via the conclusions of other research in this field. a) threads feature (bt1, bt6 and bt11) produces high heat input and vertical flow movement following the thread orientation. the result is harmonious with pervious studies [21, 22, and 24]. however, the point of distinction in this research is the threads on the pin cause open tunnel defect in the advanced side on the bottom surface of the substrate and lead to excessive flash. this effect can be termed a drill effect as discussed above. a b samir ali amin al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 111 (2018) 8 table 5, results of mechanical properties tests notes b. f (kn) w. eff. % u.t.s (mpa) elongation (%) tool type exp. no. d = 10 mm, d = 20 mm (d = 2d) open tunnel defect --------------------------bt-1 test 1 open tunnel defect --------------------------bt-2 test 2 acceptable appearance 3.88 28.6 84.5 3.3 bt-3 test 3 acceptable appearance 4.9 35.6 105 4.1 bt-4 test 4 acceptable appearance 4.1 29.7 87.5 3.52 bt-5 test 5 acceptable appearance 2.3 25.4 75 2.7 bt-6 test 6 d = 8 mm, d =16 mm (d = 2d) open tunnel defect ------------------------bt-7 test 7 acceptable appearance 5.5 40.8 95.5 5.15 bt-8 test 8 acceptable appearance 4.8 34.6 120 3.97 bt-9 test 9 acceptable appearance 2.5 30.2 102 3.4 bt-10 test 10 acceptable appearance 4.5 32.4 89 3.8 bt-11 test 11 d = 12 mm, d = 24 mm (d = 2d) open tunnel defect -------------------------bt-12 test 12 cutting defect -------------------------bt-13 test 13 cutting defect -------------------------bt-14 test 14 cutting defect -------------------------bt-15 test 15 cutting defect -------------------------bt-16 test 16 d = 8, 10 and 12 mm (respectively) (d = 2.5 d) acceptable appearance 5.75 47.5 140 5.57 bt-17 test 17 acceptable appearance 4.7 36 106 4.3 bt-18 test 18 acceptable appearance 5.1 33.9 100 3.88 bt-19 test 19 d = 8 mm, d = 24 mm (d = 3d) acceptable appearance 5.7 65.4 193 6.1 bt-20 test 20 incomplete --------------------------bt-21 test 21 flash (scraping) --------------------------bt-22 test 22 acceptable appearance 5.1 45.1 133 5.45 bt-23 test 23 b) the visual analysis denotes that the gap of the bobbin tool effects on the welded appearance. when the gap was bigger than the thickness of the substrate, there were incomplete joints and voids because of lack of strength in forging (thrust load). when the gap was lower than thickness, the edge of the shoulder scraped very thin layer of the surface of the substrate that leaded to produce an excessive flash and reduce the thickness of the plate. consequently, the gap between shoulders must be equal to the thickness of the work-piece because it is the one with superior properties, which is harmonious with other study [4, 25]. c) in general, the bobbin tool (tb-10) created a good weld joint compared to that was produced by (tb-5). the reason of this is the tool (tb-10) had smaller dimensions than (tb-10). the reduction of strength is supposed to be on account of the amount of area (volume of material sweeping) that was influenced via the bobbin tool during welding process [26]. this interpretation applies to others tools. d) the design of shoulders influences the generation of heat [26]. for the thickness of plate as used in this investigation, the needed heat generation could readily be taken out by the two sides of the bobbin tool features. shoulder diameter has significant effect to improve the welding zone properties. the swell in the diameter of the shoulder means the growing of the friction area and thus increases the heat generated. large amount of heat input is desired to break the grain boundary in transverse the welding through the work-piece [8]. the tunnel flaw at sample (tb-10) is elucidated that the reduced zone of provided heat via the smaller shoulder diamete probably resulted in premature solidification of the welding zone. the premature solidification and the tool dimension and samir ali amin al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 111 (2018) 9 its influence on the flow stress stated in [27, 28, and 29]. the above reason explains the results of welding obtained from (tb-10) and (tb-23), see figure (10). fig. 10. a) internal void (bt-10), b) perfect crosssection welded zone (bt-23). 4. conclusions the overall aim of this investigation was to better comprehend the influence of tool geometry (features and dimensions) on the weld joint quality and select the best tool design for bobbin kind friction stir welding. so, from the present wok, the followings can be concluded: 1straight cylindrical probe with four flats created a free 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[29] padmanaban g, balasubramanian v. selection of fsw tool pin profile, shoulder diameter and material for joining az31b magnesium alloy – an experimental approach. mater des 2009; 30:2647–56. )2018( 1-11، صفحة 3د، العد14دجلة الخوارزمي الهندسية المجلم سمير علي امين 11 على الخواص الميكانيكية (bobbin)دراسة تأثير تصميم عدة اللحام بالخلط االحتكاكي نوع (t6-6061)لسبيكة المنيوم الحمزة فاروق محمد*** مهند يوسف حنا** سمير علي أمين* التكنولوجيةقسم الهندسة الميكانيكية/ الجامعة *،**، *** alrabiee2002@yahoo.com :البريد االلكتروني * mohannad_hanna@yahoo.com: البريد االلكتروني ** alhamza88f@yahoo.com :البريد اإللكتروني *** الخالصة ، حيث يتم لحام قطعة العمل من الوجهين نفسها لطريقةل) يكون مختلف عن اللحام المتعارف علية bobbinاللحام بالخلط االحتكاكي بأداة تشبه البكرة ( . يتضمن هذا األسلوب لحام اللوحين من دون االنصهار. في هذا العمل، تم التحقق من تأثير تصميم األداة على الخواص نفسها لشوطلاالعلى و االسفل في كذلك ،و(bobbin)الملحومة بطريقة اللحام الخلطي االحتكاكي نوع وملم) ٦٬٢٥و بسمك ( (t6-6061)الميكانيكية لوصالت اللحام لسبيكة االلمنيوم نوع أوجه، أسطواني مستقيم ٣. خمسة أشكال مختلفة لوتد أداة اللحام (أسطواني مستقيم مسنن، أسطواني مستقيم ذو (bobbin)تحديد أفضل تصميم ألداة اللحام نوع أوجه) وبأبعاد مختلفة لألداة ( الدبوس و األكتاف ) استخدمت ألجراء عملية ٤ستقيم مسنن ذو أوجه و أسطواني م ٣أوجه، أسطواني مستقيم مسنن ذو ٤ذو ها ألختيار التصميم األفضل ألداة اللحام نوع ؤاللحام. أتجاه عملية اللحام كان عموديا على أتجاه الدرفلة أللواح األلمنيوم. اختبارات الشد واالنحناء تم اجرا )bobbin٨أوجه، بقطر للوتد ( ٤ي افضل الخواص الميكانيكية لمنطقة اللحام. األداة ذات االسطواني المستقيم ذو ) والتي تعط mm) ٢٤) واالكتاف mm ( ) نسبة الى مقاومة %٦٥٫٤كيلو نيوتن) وأفضل كفاءة لحام ( ٥٫٧) مع أقصى قوة انحناء (%٦٫١ميكا باسكال) وأستطالة ( ١٩٣أعطت افضل مقاومة شد ( الشد. (microsoft word \343\355 \346\323\307\343\355 \346\324\320\35472-82) al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 14, no. 4, december, (2018) p.p. 7282 experimental and numerical investigation for simulation of thermophysical properties for polypropylene 575 polymer melts in single screw extruder may m. ismail* sami d. salman** shatha k. muallah*** *,**,*** department of biochemical engineering / al-khwarizmi college of engineering /university of baghdad *email: maymunir766@gmail.com **email: sami.albayati@gmail.com ***email: shatha_engr@yahoo.com (received 13 february 2018; accepted 15 april 2018) https://doi.org/10.22153/kej.2018.04.003 abstract a numerical model for polypropylene 575 polymer melts flow along the solid conveying screw of a single screw extruder under constant heat flux using ansys-fluent 17.2 software ha s been conducted. the model uses the thermophysical properties such as viscosity, thermal conductivity, specific heat and density of polypropylene 575 that measured as a function of temperature, and residence time data for process simulation. the numerical simulation using cfd models for single screw extruder and the polymer extrusion was analysed for parameters such as (thermal conductivity, specific heat, density and viscosity) reveals a high degree of similarity to experimental data measured. the most important outcome of this study is that geometrical, parameter and conditions have been obtained from the simulation used to minimize the size, cost and time of operation for extruder. keywords: ansys fluent, cfd, single screw extruder, numerical simulation, polymer melt, polypropylene575, solid works, thermophysical properties. 1. introduction the production procedure of polymer slides begins in an extruder, where extrusion is a process of production long products of constant crosssection (sheets, rods, pipes, wire insulation, coating films). identifying of rheological behaviour for polymers is necessary for finding the best or most favourable situation of melt processing, like temperature, rate of flow, and for estimating the desirable machine capacity [1]. many different laws have been used to describe the flow of these complex material such as power law, bingham law, bird-carreau law and carreau-yasuda law [2]. simulation software is applied to enhance the turnaround times, productivity, quality, and resource employment in polymer processing. however, the feasibility of a simulation software is extremely dependent on the reliability of the material data and models in its database, the skilfulness of the employer, and on the understanding of the material behaviour [1]. this study deals with the single screw extruder design for polymeric processing using (cfd) software ansys fluent 17.2, while the geometrical creation by using solid works 2016 [2]. fig. (1) show the commercial single screw extruder and fig. (2a) show the schematic diagram of single screw extruder. may m. ismail al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 7282 (2018) 73 fig. 1. single screw extruder equipment (sj30 / 28). fig. 2a. schematic diagram of the extruder. 2. a experimental setup fig. 2b. schematic diagram of the extruder with setup details. 2. b experimental work the experiments were carried out to study the effects of thermophysical properties such as (viscosity, thermal conductivity, specific heat and density) for polypropylene 575 through single screw extruder at a different flow rate, variable rpm and constant heat flux (7803.571 w/m2), to see more details show fig. (2b). the physical and thermophysical properties of the polymer were measured as a function of temperature by (ar-g2) rotational rheometer, (plate-plate) geometry [3, 4] (tci thermal conductivity analysers), and dsc equipment [5]. the data obtained from this equipment was used as polynomial equation then employed as input data for simulation process as illustrated in the equations (a-d) below. fig. (3) shows the experimental behaviour of thermophysical properties for polypropylene 575 at different temperature. µ = 0.2905t2 294.5t + 76012 ... (a) k = 8e-06t2 0.0081t + 2.2014 ... (b) cp = -0.1036t2 + 102.73t – 22458 ... (c) ρ = -0.0184t2 + 17.98t 3491.1 ... (d) in addition, the laboratory experiments were carried out on the laboratory extruder as illustrated in fig. (1). the experiments were conducted using chinese extruder in babil governorate, this part of the work involves conducting the practical experiments on the polypropylene 575 and simulating these experiments, then validates the results with the experimental work, table (1) shows the overall data of single screw extruder. may m. ismail al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 7282 (2018) 74 (a) (b) (c) (d) fig. 3. the thermophysical properties of polypropylene 575 at different temperature. (a)viscosity. (b) thermal conductivity. (c) specific heat. (d) density. table 1, overall data for the practical part of single screw extruder. 3. polymer used in this research, polypropylene 575 was used because it has a good mechanical and physical properties, such as an excellent insulator, therefore, it was used in an electrical industry, melting point ranging between (157-171) ℃, and in clinical filed due to low moisture absorption [6]. as well as polypropylene 575 is strongly influenced by the length and size of chain likewise increasing the length of chain which leads to enhancing melting point temperature because of increasing the joint between the chains [7,8]. total feed in kg m total feed rate kg/s n screw speed rpm heat flux inlet w/m2 heat flux outlet w/m2 temperature of inlet polymer °c temperature of polymer outlet °c setting temperature °c 0.25 1.812*10-4 10 7803.571 7203.57 23 157 160 0.25 2.193*10-4 20 7803.571 7626.1 23 153 160 0.25 3.472*10-4 30 7803.571 7633.48 23 148 160 0.25 5.952*10-4 40 7803.571 7750 23 143 160 0.5 2.6*10-4 10 7803.571 7201.72 23 178 180 0.5 3.33*10-4 20 7803.571 7310.335 23 175 180 0.5 4.39*10-4 30 7803.571 7540.455 23 171 180 0.5 5.56*10-4 40 7803.571 7575.45 23 168 180 may m. ismail al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 7282 (2018) 75 4. simulation process based on practical experiments, it is know that the increasing usage of (cfd) packages computational fluid dynamics to study the flow of complex melting polymer in different processing and complex devices need some usable material modelling technique. for this purpose, it is necessary to study the model describing the behaviour of polymer melting specifically. as well as, the commercial cfd packages supply only some liner model such as (the model of the linear viscous body for viscous fluids) [9, 10]. for incompressible fluids, all cfd packages simulation started from the governing equations for continuity and momentum [11]. the arithmetical models using the commercial cfd software’s (solid works 2016) for model creation, table (2) shows the dimensions of single screw extruder and (ansys fluent 17.2) used and evaluated against the experimental findings to validate the observed results. three steps of the cfd simulation process including pre-processing, solving and post-processing steps are followed to analyse the fluid flow and heat transfer model. preprocessing is the first stage in analysing and building a cfd model which taking place before the numerical solution process. in this step, the model geometries of single screw extruder were created and identified based on the boundary types, then the domain of benefits was divided into smaller segments which known as a grid (mesh) generation. this stage is the most important and the most time-consuming step in the cfd process. ansys fluent meshing has been used as a result of its simplicity and flexibility in application [12]. while in the solver step, the definition of material, operating conditions and boundary condition at an inlet, outlet, and across the whole fluid flow were selected. pressure-based solver (pbcs) was selected to solve the governing equations for heat transfer and flow. the pbcs solver can be used for a broad range of flow regimes from low-speed incompressible flow to high-speed compressible flow and hence was selected. the precise identification of the properties, parameters, the appropriate models for the solution methods, accuracy and convergence are very important factor to get a realistic solution [13]. as well as post-processing is the last step of the cfd process where the results with their parameters can be extracted and analysed using meaningful graphics, vector plots, contour plots, animations and reports. numerous of commercial post-processing packages are available to view results for analysis [14]. table 2, dimension of screw. 5. assumption for simplification of model the assumptions which were considered for simulation the model are as following: (i) the polymer fluid was assumed as non-newtonian having a pseudo plastic characteristic and incompressible fluid, (ii) the fluid flow was assumed as a laminar flow due to the rpm of screw was very low and there is no slippage between fluids and the cylinder wall, (iii) the heat flux was assumed constant with negligible radiation effects, (iv) the particles were presumed to be spherical and single phase model was used, and (v) the thermos-physical properties of fluids were variable with temperatures [15]. the following governing equations for cylindrical coordinates have been used for simulation [16]. continuity equation: ( ) ( ) ( ) 1 1 0 rv r v t r r r v z z ρ ρ θρ θ ρ ∂ ∂∂ + + ∂ ∂ ∂ ∂ + = ∂ … (1) momentum equation: 2 22 2 2 2 2 ( ) 1 [ ( ( )) 1 2 ] r r r r r z r r r v t r r z r p r r r r r r g r z r θ θ θ νν ν ν ν ρ ν ν θ µ ν ννν ρ θ θ ∂ ∂ ∂ ∂ + + ⋅ + − = ∂ ∂ ∂ ∂ ∂ ∂ ∂ − + ⋅ ∂ ∂ ∂ ∂∂∂ + ⋅ + − ⋅ + ∂ ∂ ∂ … (2) extruder length(mm) l/d ratio shaft diameter(mm) screw diameter(mm) cylinder diameter(mm) pitch (mm) screw speed(rpm) weight capacity(kg) 1000 28 14 30 35.7 25 10-40 1-8 may m. ismail al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 7282 (2018) 76 2 2 2 2 2 ( ) 1 [ ( ) 1 ] z z z z z z z z r z t r r z vp r z r r r g r z ν νν ν νθ ρ ν ν θ µ ν ν ρ θ ∂ ∂∂ ∂ + + ⋅ + = ∂ ∂ ∂ ∂ ∂∂ ∂ − + ⋅ ⋅ + ∂ ∂ ∂ ∂ ∂ ⋅ + + ∂ ∂ … (3) energy equation: 2 1 1 t t c p k r t r r r t t k k g r z z ρ ϕ ϕ ∂ ∂ ∂ = + ∂ ∂ ∂ ∂ ∂ ∂ ∂ + + ∂ ∂ ∂ ∂                 … (4) 6. results temperature contour planes were displayed illustrated in the following figuers. fig. (4) a-d at heat flux of 7803.571 w/m2 and 250 gm as a weight and fig. (8) a-d but at 500 gm as a weight, represents contour planes of the temperature distribution along the extruder with revolution per minute ranging between (10-40) rpm. increase rpm led to reduction in residance time, which affects the heating of polypropelene 575 material within the extruder.it can also be observed that the temperature of the material increased to a certain extent inside the extruder and then decreased very slightly in few degrees before the material started to exit out of extruder .this is can be seen clearly, especially when the rpm increased, where the loss in temperature increased. also it can be inferred that temperature of polymer near the screw surface and near the barrel wall is the highest. the polymer material in the middle has lower temperature [15]. fig. (5) a-d at a heat flux of 7803.571 w/m2 and 250 gm as a weight and fig. (10) a-d with 500 gm as a weight, represent contour planes of the density behavior along the extruder at rpm ranging between (10-40). where increasing temperature led to increase density to a certain extent, this is observed especially when increasing the rpm. because of the interstitial materials that contain air between their granules, it is known that by increasing the temperature leads to an increase in the density of these materials, because when the temperature increases these grains begin to melt, which leads to reducing the volume with the mass constant, thus led to increase density [17]. fig. (6) a-d at heat flux 7803.571 w/m2 and 250 gm as a weight and, fig. (11) a-d but with 500 gm as a weight, represent contour planes of the viscosity behavior along the extruder at rpm ranging between (10-40). where increase temperature led to decreasing the viscosity and this is clearly observed in the practical results when the viscosity decreased by increasing the temperature. fig. (7) a-d at heat flux 7803.571 w/m2 and 250 gm as a weight, and fig. (12) with 500 gm as a weight, represent contour planes of the thermal conductivity behavior along the extruder at rpm ranging between (10-40). where increasing the temperature led to slightly decreasing in thermal conductivity because of polymeric materials used as an insulator. the phonon transport is the main mechanism for interaction of heat energy with each other and with subatomic particles [18]. drag phonon is the increase in effective mass of electrons conduction or valence holes due to interactions with crystal lattice in moving the electron. as an electron moves the past atoms in the lattice, its polarizes or charge distorts the nearby lattice. this effect leads to an electron decrease (as may be the case, hole) mobility, which results in a thermal conductivity decreased [19]. fig. (8) a-d at heat flux 7803.571 w/m2 and 250 gm as a weight, and fig. (13) a-d with 500 gm as a weight, represent contour planes of the specific heat behavior along the extruder at rpm ranging between (10-40). where increasing the temperature led to increase in specific heat. specific heat capacity is a measuring of substance ability to absorb heat. the heat first goes to increase the kinetic energy of the molecules. these molecules also can store energy in rotation and vibration. as heats up the substance, the average kinetic energy of molecules increases. the collisions impart energy enough to allow rotation occur. then rotation contributes to internal energy and raises the specific heat capacity of material [20]. it is clearly shawn in fig. (14 & 15) a, b, c, & d that a significant matching between the experimental results and the results of process simulations with a slight difference. this difference resulting from the degree of complexity of the form "single screw extruder" and the process of mesh generation. may m. ismail al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 7282 (2018) 77 fig. 4. temperature contour plane at 250 gm. fig. 5. density contour plane at 250 gm. fig. 6. viscosity contour plane at 250 gm. fig. 7. thermal conductivity contour plane at 250 gm. fig. 8. specific heat contour plane at 250 gm. fig. 9. temperature contour plane at 500 gm. may m. ismail al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 7282 (2018) 78 fig. 10. density contour plane at 500 gm. fig. 11. viscosity contour plane at 500 gm. fig. 12. thermal conductivity contour plane at 500 gm. fig. 13. specific heat contour plane at 500 gm. (a) (b) may m. ismail al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 7282 (2018) 79 (c) (d) fig. 14. thermophysical properties of polypropylene 575 for experimental and simulation results at different temperature (a)viscosity, (b) thermal conductivity, (c) specific heat, (d) density. (a) (b) (c) (d) fig. 14. thermophysical properties of polypropylene 575 for experimental and simulation results at different temperature (a) viscosity, (b) thermal conductivity, (c) specific heat, (d) density. may m. ismail al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 7282 (2018) 80 7. conclusion the numerical values showed closer fitting to the experimental values in the extruder. where viscosity and thermal conductivity decreased with increasing temperature along the extruder. while the specific heat and density increased with temperature increased along the extruder. consequently, this study was successfully validated by cfd simulation for single screw extruder. acknowledgments the authors would like to thank al-furat general company for chemical industries and pesticides, in babil governorate for serving and helpful work in the laboratory. 8. references [1] johanna aho, "rheological characterization of polymer melts in shear and extension : measurement reliability and data for practical processing", a ph.d thesis for the degree of doctor of materials science intampere university of technology, finland, issn1458-8045, (2011). 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[15] manohar baalaganapathy and periasamy c., "computational fluid dynamics simulation of single screw extruders in cable industries ". international journal of research in engineering and technology 5 (3): pp. 85–89, (2016). [16] r. b. bird, w. e. stewart, and e. n. lightfoot, “transport phenomena”, hand book, 2nd edition, wiley: ny, (2002). [17] jinping qu, baoshan shi, and hezhi he, "influence of vibration on density of polymer solid granules in single screw extruder". polymer plastics technology and engineering, 46: pp. 233–237. doi: 10.1080/03602550601152911, (2007). [18] i.a. tsekmes, r. kochetov, p.h.f. morshuis, and j.j smit, "thermal conductivity of may m. ismail al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 7282 (2018) 81 polymeric composites: a review", ieee international conference on solid dielectrics, bologna, italy, pp. 678–681, (2013). [19] kittel charles, "introduction to solid state physics", 7th ed., john wiley and sons, inc. (1996). [20] varghabutler, a. wilhelm and hasan a., "specific heats of polymer powders by differential scanning calorimetry". traduit par le journal, vol. 60: pp. 1853–1856, (1982). )2018( 72-82، صفحة 4د، العد14دجلة الخوارزمي الهندسية المجلم مي منير اسماعيل 82 وليبروبيلين التحقيق التجريبي والعددي لمحاكاة الخصائص الحرارية الحرارية للبوليمر الذائب ب البرغي الواحد يفي الطارد ذ ٥٧٥ ***شذى كاظم معله **سامي داوود سلمان *مي منير اسماعيل جامعة بغداد /كلية الهندسه الخوارزمي /ةاالحيائي ةالكيميائي ةقسم الهندس*،**،*** maymunir766@gmail.com :البريد االلكتروني* sami.albayati@gmail.com :البريد االلكتروني** shatha_engr@yahoo.com :البريد االلكتروني*** الخالصة الذي يتدفق على طول الطارد الذي يكون ذا مسمار مفرد تحت كمية حرارة معلومة ، معدل تدفق ٥٧٥النموذج العددي للبوليمر الذائب بولي بروبلين ). يستخدم النموذج الخصائص الريولوجية للبوليمرالذي tneulf-sysna ١٧٫٢ه بأستخدام برنامج (ؤدورة بالدقيقة مختلفة حيث تم اجرامتغير، وكذلك و ارة) لمعامالت مثل درجة الحرdfcدالة لدرجة الحرارة لمحاكاة العمليات التجريبية. حيث تم تحليل نتائج المحاكاة العددية بأستخدام نموذج (بوصفه يقاس حد النتائج المهمة لهذا البحث أالتوصيليه الحرارية وكذلك الكثافه حيث اثبتت درجة عالية من التشابه مع البيانات التجريبية المقاسة. وو الكثافه النوعيةو اللزوجة تم الحصول على الشكل الهندسي وتحديد ظروف العمل لتقليل التكلفة ووقت التشغيل. (microsoft word \337\307\344\355 \346\307\310\312\345\307\34134-44) vibration analysis of cross-ply plates under initial stress using refined theory ibtehal abbas sadiq* kani hussein bawa** *,**department of mechanical engineering / university of baghdad *email:ebtialabas@yahoo.com **email:kanihussein1991@gmail.com (received 2 january 2018; accepted 22 may 2018) https://doi.org/10.22153/kej.2018.05.002 abstract natural frequency under initial stresses for simply supported cross-ply composite laminated plates (e glassfiber) are obtained using refind theory (rpt). this theory accounts for parabolic distribution of the transverse shear strain through the plate thickness and satisfies the zero traction boundary conditions on the surfaces of the plate without using shear correction factors. the governing equations for eigen value problem under initial stress are derived using hamilton’s principle and solved using navier solution for simply supported cross-ply symmetric and antisymmetric laminated plates. the effect of many design factors such as modulus ratio, thickness ratio and number of laminates on the natural frequency and buckling stresses of orthotropic plates are studied. the results are compared with other researcher. keyword: composite laminated plate, buckling analysis, free vibration analysis, refined plate theory. 1. introduction laminated composite plates have very importance in the engineering applications because of their useful features so a many variety of laminated theories for static and dynamic behavior have been developed such as approximate, experimental and exact methods. [1] presented static analysis using higher-order refined theory of angle ply plate and sandewich plates hitherto. no requirement to use shear correction factors (scf), because the transverseshear strains vary parabolicaly from side to side which lead to vanish the shear-stresses on the upper and bottom surface of the plate. from principle of potential energy, the equations of equilibrium are derived and solved by using navier-type method. correctness of the theoretical preparations and the solution method confirmed by comparing the results with other theory described in the literature. [2] presented buckling analysis of ss plate exposed to in-plane loading using refined plate theory of orthotropic and isotropic plates. the governing equations g.e which derivative from the principle of virtul-displacements, and solved by using the navier method. this theory is simple, comparable to the(fsdt) theory and there no exists a need for using scf. [3] studied a two-variable refind theory (rpt) of lamineted composite plates. the theory contents the zero traction b.c on the upper and bottom faces of the plate without wanting to use scf. the equations of motion are derivative using hamilton’s principle (h.p) and solved using naveir method of angle-ply and cross-ply antisymmetric laminate. this theory is simple and accurate in solving the buckling behaviors and static bending of laminated composite plates. [4] studied free vibration of laminated composite plates using two variable refined plate theory (rpt) and using hamilton’s principle to derive the equations of motion, and these equations solved using navier solutions of cross-ply and angle-ply antisymmetric laminates. this theory is accurate and effective in obtain the natural frequencies n.f of laminated composite plates. [5] studied the buckling analysis using refind theory for orthotropic plates. no requirement to use scf in this theory and the governing equations solved al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 14, no.4, december, (2018) p.p. 3444 ibtehal abbas sadiq al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 3444 (2018) 35 using levy-type method. it considering the effect of some design limitations such as boundary conditions, orthotropy ratio, thickness ratio and loading condition on the critical-buckling load. [6] presented free-vibration investigation of functionaly arranged material (fgm) sandwich rectangular plates by the four variable refined theory (rpt) which not requirement to use scf. the equation of motion achieved using hamilton’s principle for the (fgm) sandwich plates and these equations solved by using the navier type. this theory simple and accurate in resolving the freevibration behavior of the functionaly arranged material sandwich plates when its results comparing with other theories such as classical laminated theory(clp), first order theory (fsdt). [7] presented free vibration analysis of simply supported plate which made of functionaly arranged materials using four variable refind theory. no requirement to use shear correction factors, because the transverse-shear strains vary parabolicaly from side to side the thickness which lead to disappear the shear stresses on the upper and bottom faces of the plate. from the principle of virtual displacements, the governing equations for the (fgm) rectangular plates are derived and solved by using navier-type method. the natural frequencies are found using the ritz method in the case of fg clamped plates. the strength of this present theory which gave accurate free vibration of fg plate shown by comparing the present results with others theories and also the influence of vying rises, aspect ratios, and thick ratio on the freevibration of the fg plates is showed. [8] presented free vibration analysis of rectangular plate with two opposite edges simply supported (ss) and the other two edges having arbitrary boundary conditions using 'refined plate theory'. from the principle of virtual displacements, the governing equations are derived and solved by using the levy-type method. no need to use shear correction factors in this theory, it considering the effect of some design parameters such as boundary conditions, modulus ratio, and aspect ratio on the natural frequency. in present work, the equation of motion of refined plate theory are programming to find the critical buckling and fundamental natural frequency for cross-ply plate for different thickness ratio, symmetric and antisymmetric and orthotropy ratio, while to obtain vibration characteristic of plate under initial stress, we derive equation of motion depending on refined plate theory for simply supported plates using navier solution. 2. theoretical analysis 2.1 displacement field in present work, a rectangular plate of total thickness (h) of (n) orthotropic layers with the coordinate system as shown in fig (1) are considered the displacement of refined plate theory (rpt) which satisfies equilibrium conditions at the top and bottom faces of the plate without using shear correction factor is developed. the transverse displacement w contains three components; bending ��� , extension �� and shear ��� which these components are functions of coordinates x, y, and time t only. similarly, the displacements u in x-direction and v in y-direction have bending, extension and shear components [3]. u= + �� + �� v= � + ��� + ��� w�x‚y‚z‚t� = w��x‚y‚t� + w���x‚y‚t� + w���x‚y‚t� the shear components �� and ��� , ��� lead to the parabolic variations of shear strains � !, �"! and to shear stresses # !, #"! through the thickness of the plate in such a way that shear stresses # !, #"! are zero at the bottom and top surfaces of the plate. ��= $ %&' − )* +!�,-. /012/ ���= $ %&' − )* +!�,-. /012/" the following displacement field assumptions [3]: 3�4‚5‚$‚6� = u�x‚y‚t� − z +89:;8< , + z %&' − )* +=�,-. 89>?8< @�4‚5‚$‚6� = v�x‚y‚t� − z +89:;8b , + z %&' − )* +=�,-. 89>?8b c�4‚5‚$‚6� = ���4‚5‚6� + ����4‚5‚6� +����4‚5‚6� …(1) for small strain, the strain-displacement relations take the form: d = /e/ d" = /f/" d " = &+/e/" + /f/ , = &� " d ! = &+/e/! + /0/ , = &� ! d"! = &+/f/! + /0/", = &�"! …(2) by substituting eq. (1) into eq. (2) to give: d = /e/ − $ /g0hi/ g + $ [&' − )* +!�,-] /g012/ g d" = /f/" − $ /g0hi/"g + $ [&' − )* +!�,-] /g012/"g ibtehal abbas sadiq al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 3444 (2018) 36 � " = /e/" + /f/ − 2$ /g0hi/ /" + 2$ [&' −)* +!�,-] /g012/ /" �"! = /0m/" + [)' − 5 =g�g] /012/" � ! = /0m/ + [)' − 5 =g�g] /012/" …(3) the strain field is: o d d"� "p = q d rd" r� "r s + $ q t �t"�t "� s + u q t � t"�t "� s v� !�"!w = x� !��"!� y + z x � !� �"!� y … (4) where: q d rd" r� "r s = ⎩⎪⎨ ⎪⎧ /e/ /f/" /e/" + /f/ ⎭⎪⎬ ⎪⎫ q t �t"�t "� s = ⎩⎪⎨ ⎪⎧ − /g0hi/ g− /g0hi/"g−2 /g0hi/ /" ⎭⎪⎬ ⎪⎫ q t � t"�t "� s = ⎩⎪⎨ ⎪⎧ − /g012/ g− /g012/"g−2 /g012/ /" ⎭⎪⎬ ⎪⎫ , x� !��"!� y = q/0m/ /0m/" s , x � !� �"!� y = q/012/ /012/" s f= − &' $ + )* $ +!�, ‚ z = )' − 5 +!�, … (5) fig. 1. coordinate system of laminated plates. 2.2 principle of virtual work using hamilton’s principles, the equations of motion of the refined plate theory will be derived. reddy, 2004 0 = c �d3 + d@ − de�fr g6 … (6) • the virtual strain energy d3 is: d3 = [c +h [# dd i + σbdd"i + σ<bdγ<bl +lmn2g2gσb=γb=l + σ<=γ<=l ] ∂x ∂y, p$] = 0 … (7) substituting eq. (4) into eq. (7) d3 = c qn<dε<r + nbdεbr + n<bdγ<br + m<�dk<� +mb�dkb� + m<b� dk<b� + m<�dk<� + mb�dkb� +m<b� dk<b� + qb=� dγb=� + q<=� dγ<=� + qb=� dγb= � +q<=� dγ<=� w ∂x ∂y =0 … (8) where: xy ‚ y" ‚y "z = c x# ‚ #"‚ # "zg$ �/-n�/= ∑ c x# ‚ #"‚ # "zg$!}~�!}�i�& x� � ‚ �"� ‚ � "� z = c x# ‚ #"‚ # "z$ g$ �/-n�/=∑ c x# ‚ #"‚ # "z$ g$!}~�!}�i�& xm<� ‚ mb� ‚ m<b� z = c xσ< ‚ σb‚ σ<bzf dz �/-n�/=∑ c xσ< ‚ σb‚ σ<bzf dz=�~�=��l�& x� !� ‚ �"!� ‚�"!� ‚� !� z =c x# ! ‚ #"! ‚z# ! ‚ z#"!z g$ �/-n�/ =∑ c x# ! ‚ #"! ‚z# ! ‚ z#"!z g$!}~�!}�i�& … �9� the virtual strains are known in terms of virtual displacement eq.(4) and then substituting the virtual strain into eq. (8) and integrating by parts to relative virtual displacement (d , d�, d�� ‚d��� ‚ d���) in range of any differentiation, then we get: 0 = c[− d /��/ − d� /��/" − d /���/" − d� /���/ − d��� /g��h/ g − d��� /g��h/"g −2 d��� /g���h/ /" − d��� /g��1/ g − d��� /g��1/"g −2 d��� /g���1/ /" − d�� /���m/" − d�� /���m/ − d��� /���1/" − d��� /���1/ ] ∂x ∂y … (10) the virtual work done dv is: dv = − � �n<rd 8g�9��9:;�9>? �8<g � ∂x ∂y = 0 � … (11) de = c c �2gn2g �� � − $ /0� hi/ + u /0� 12/ � �d � − $ �/0� hi/ + u �/0� 12/ � + ��� − $ /0� hi/" + u /0� 12/" � �d�� − ibtehal abbas sadiq al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 3444 (2018) 37 $ �/0� hi/" + u �/0� 12/" � + [�� � + �� �� + �� ��][d�� � +d�� �� + d�� ��]} g� de = c �+i&u� − i89� :;8< + i' 89� >?8< , δu� + +−i-u� +i* 89� :;8< − i) 89� >?8< , � 89� :;8< + +i'u� − i) 89� :;8< +i� 89� >?8< , � 89� >?8< + +i&v� − i89� :;8b + i' 89� >?8b , δv� ++−i-v� + i* 89� :;8b − i) 89� >?8b , � 89� :;8b + +i'v� −i) 89� :;8b + i� 89� >?8b , � 89� >?8b + �w� � + w� �� +w� ���δw� � + �w� � + w� �� + w� ���δw� � + �w� � +w� �� + w� ���δw� ��� dx dy …(12) where: x�& ‚�‚�* ‚�' ‚�) ‚ �� z = c �2gn2g �1‚ $‚ $-‚ u�$�‚ $u�$�‚ [u�$�]� g$ 2.3 equation of motion the euler-lagrange is obtained by substituting equation(8 12) into equation (6), then setting the coefficient of (d , d�, d�� ‚d��� ‚ d���) of eq.(6) to zero separately, this give five equations of motion as follows: δu ∶ 8� 8< + 8� ¡8b = i&u¢ δv ∶ 8� ¡8< + 8�¡8b = i&v¢ δw�� : 8g¤ :8<g + 2 8g¤ ¡:8< 8b + 8g¤¡:8bg + n�w� =i&�w¢ � + w¢ �� + w¢ ��� − i* 8g8¥g �8g9:;8<g + 8g9:;8bg � δw�� ∶ 8g¤ >8<g + 2 8g¤ ¡>8< 8b + 8g¤¡>8bg + 8¦ §>8< + 8¦¡§>8b +n�w� = i&�w¢ � + w¢ �� + w¢ ��� − i� 8g8¥g �8g9>?8<g +8g9>?8bg � δw� ∶ 8¦ §�8< + 8¦¡§�8b + n�w� = i&�w¢ � + w¢ �� +w¢ ��� …(13) where: n�w� = n<r ∂-�w� + w�� + w���∂x-+ nbr ∂-�w� + w�� + w���∂y+ 2n<br ∂-�w� + w�� + w���∂x ∂y the result forces are given by: reddy [9]. q y y"y "s = ∑ c o # #" # b p g$!}~�!}�i�& q � ��"�� "� s = ∑ c o # #" # b p $ g$!}~�!}�i�& q � ��"�� "� s = ∑ c o # #" # b p u g$!}~�!}�i�& x� !��"!� y = ∑ c v# ! #"! w g$!}~�!}�i�& x� !��"!� y = ∑ c v# ! #"! w z g$!}~�!}�i�& …(14) the plane stress reduced stiffness �¨© is: �&& = ª�&nf�gfg� ‚ �-& = f�gªg&nf�gfg� �-= ªg&nf�gfg� , ��� = «&‚ �'' =«-* ‚ �)) = «&* from the constitutive relation of tf� layer lamina, the transformed stress-strain relation are: ⎩⎪⎨ ⎪⎧ # #"# "#"!# !⎭⎪⎬ ⎪⎫ = ⎣⎢⎢ ⎢⎡�&& �& 0 0 0�-& �- 0 0 0 0 0 ��� 0 0 0 0 0 �'' 0 0 0 0 0 �))⎦⎥⎥ ⎥⎤ ⎩⎪⎨ ⎪⎧ d d"� "�"!� ! ⎭⎪⎬ ⎪⎫ …(15) the force results are related to the strains by relations: q y y" y "s = ²a&& a&a&�a&a-a-�a&� a-� a��´ q d rd" r � "r s+ ²b&& b&b&�b&b-b-�b&� b-� b��´ q t �t"� t "� s+ ¶·&&� ·&-� ·&��·&-� ·--� ·-��·&�� ·-�� ·��� ¸ q t �t"� t "� s q � ��"� � "� s = ²b&& b&b&�b&b-b-�b&� b-� b��´ q d rd" r � "r s + ²d&& d&d&�d&d-d-�d&� d-� d��´ º k<�kb� k<b� » + ¶d&&� d&-� d&��d&-� d--� d-��d&�� d-�� d��� ¸ q t �t"� t "� s ibtehal abbas sadiq al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 3444 (2018) 38 q � ��"� � "� s = ¶b&&� b&-� b&��b&-� b--� b-��b&�� b-�� b��� ¸ q ε<rεb r γ<br s + ¶d&&� d&-� d&��d&-� d--� d-��d&�� d-�� d��� ¸ º k<�kb� k<b� » + ¶h&&� h&-� h&��h&-� h--� h-��h&�� h-�� h��� ¸ q k<�kb� k<b� s x�"!�� !� y = %½'' ½')½') ½)). x�"!�� !� y + %½''� ½')�½')� ½))� . x�"! �� !� y x�"!�� !� y = %½''� ½')�½')� ½))� . x�"!�� !� y + %½''� ½')�½')� ½))� . x�"! �� !� y … �16� where: +a ¿à ‚ b ¿à ‚ d ¿à ‚ b ¿à � ‚ d ¿à � ‚ h ¿à� , = � qá ¿à �n��1‚ z ‚ z-‚ f�z�‚ z f�z�‚ [f�z�]� dz 2.4 navier’s solution to solve equations of motion (15-16), navier’s generalized displacements are used which satisfy the boundary conditions of the problem as shown in fig.2, therefore simply supported boundary conditions are satisfied by assuming the following form of displacements: reddy [ 9] u = ∑ ∑ uâã äã�&äâ�& cosαx sin βy v = ∑ ∑ vâã sin αxäã�&äâ�& cos βy w�� = ∑ ∑ w��âã sin αxäã�&äâ�& sin βy w�� = ∑ ∑ w��âã sin αxäã�&äâ�& sin βy w� = ∑ ∑ w�âã sin αxäã�&äâ�& sin βy …(17) where: α = â ë� , β = ã ë� and (uâã vâã w��âã w��âã w�âã � are arbitrary constants. the following stiffnesses are zero if the navier solution exists, a&� = a-� = d&� = d-� = ì&�� = í&�� = í-��= 0 ·&= ·&� = ·-� = ·�� = ·&-� = ·&�� = ·-��= ·��� = 0 ½') = ½')� = ½')� = 0 fig. 2. boundary condition for simply supported plate. 2.5 vibration analysis developing mass matrix and stiffness matrix from solution of homogeneous equations, when mechanical loading is equal to zero for free vibration, then eigenvalue equation is derived and the natural frequencies of vibration for simply supported plate are obtained. ⎣⎢⎢ ⎢⎡ s&& s&s&*s&s-s-*s&* s-* s** s&' 0s-' 0s*' 0s&' s-' s*'0 0 0 s'' s')s') s))⎦⎥⎥ ⎥⎤ ⎩⎪⎨ ⎪⎧ uâã vâã w�âã w�âã w�âã ⎭⎪⎬ ⎪⎫ + ⎣⎢⎢ ⎢⎡m&& 0 00 m-00 0 m** 0 00 0m*' m*)0 0 m*'0 0 m&& m'' m')m&& m))⎦⎥⎥ ⎥⎤ ⎩⎪⎨ ⎪⎧ u¢ âãv¢âãw¢ ��âãw¢ ��âãw¢ �âã ⎭⎪⎬ ⎪⎫ = ⎩⎪⎨ ⎪⎧00000⎭⎪⎬ ⎪⎫ |[s] − �-[m]| = 0 where ñs¿àò = stiffness matrix elements and ñm¿àò = mass matrix. 2.6 buckling the applied loads for buckling analysis, are supposed to be in-plan forces ibtehal abbas sadiq al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 3444 (2018) 39 y r = −yr ‚ y"r = γnr ‚ γ = n<ry"r ‚ y "r = 0 ⎣⎢⎢ ⎢⎢⎡ ó&& ó& ó&*ó&ó- ó-*ó&* ó-* ó** − yr�ô+ �õ-� ó&' 0ó-' 0 ó*' − yr�ô+ �õ-� −yr�ô+ �õ-�ó&' ó-' ó*' − yr�ô+ �õ-�0 0 −yr�ô+ �õ-� ó'' − yr�ô+ �õ-� ó') − yr�ô+ �õ-�ó') − yr�ô+ �õ-� ó)) − yr�ô+ �õ-� ⎦⎥⎥ ⎥⎥⎤ ∗ ⎩⎪⎨ ⎪⎧ uâã vâã w��âã w��âã w�âã ⎭⎪⎬ ⎪⎫ = ⎩⎪⎨ ⎪⎧00000⎭⎪⎬ ⎪⎫ 2.7 free vibration analysis under initial stress the natural frequency is investigated with action of buckling, a ratio critical load (d) is applied. the effect of the load ratio (d) is studied to present the behavior of the plate and its frequency. ⎣⎢⎢ ⎢⎢⎡ ó&& ó& ó&*ó&ó- ó-*ó&* ó-* ó** − yr�ô+ �õ-� ó&' 0ó-' 0 ó*' − yr�ô+ �õ-� −yr�ô+ �õ-�ó&' ó-' ó*' − yr�ô+ �õ-�0 0 −yr�ô+ �õ-� ó'' − yr�ô+ �õ-� ó') − yr�ô+ �õ-�ó') − yr�ô+ �õ-� ó)) − yr�ô+ �õ-� ⎦⎥⎥ ⎥⎥⎤ ⎩⎪⎨ ⎪⎧ uâã vâã w��âã w��âã w�âã ⎭⎪⎬ ⎪⎫ + ⎣⎢⎢ ⎢⎡m&& 0 00 m-00 0 m** 0 00 0m*' m*)0 0 m*'0 0 m&& m'' m')m&& m))⎦⎥⎥ ⎥⎤ ⎩⎪⎨ ⎪⎧ u¢ âãv¢âãw¢ ��âãw¢ ��âãw¢ �âã ⎭⎪⎬ ⎪⎫ = ⎩⎪⎨ ⎪⎧00000⎭⎪⎬ ⎪⎫ 3. results and discussion 3.1 vibration and buckling results the fundamental natural frequency and critical buckling for cross-ply plate with different design parameters for simply supported boundary condition, is analyzed and solved used matlab programming. we derive equation of motion depending on refined plate theory using navier solution to obtain vibration characteristic of plate under initial stress. to examine the validity of the derived equation and performance of computer programming for vibration and buckling stress of cross-ply laminated simply supported plate, a comparison with others researchers for different layers, thickness ratio (a/h) and orthotropy ratio (e1/e2). the non-dimensional natural frequency of antisymmetric cross-ply two, four, six and ten layer of thick plate (a/h=5) as a function of orthotropy ratio (e1/e2) shown in table (1) for the mechanical properties [«&= «&* = 0.6 e ‚ «-* =0.5 e ‚ �&= 0.25] while table (2) shows the non-dimensional fundamental frequencies of antisymmetric square laminated plate for various values of thickness ratio and modulus ratio (e1/e2=40). the natural frequency shows good agreement with other researchers. the present theory is also close agreement with other theory for critical buckling as shown in table (3) which compared with [2] for non-dimensional uniaxial buckling load of simply supported antisymmetric layer for (a/h=10), while table (4) and table (5) are compared with [9] which show the nondimensional uniaxial and biaxial buckling load of simply supported antisymmetric cross-ply for two and eight layers for various thickness ratio (a/h) and as a function of modulus ratios (e1/e2). 3.2 vibration of plate under initial stress results vibration analysis of present work is used but adding initial in-plane stress to investigate the validity of refined theory for such case. table (6) shows non-dimensional natural frequency under various uniaxial loads ratio(d) for simply supported cross-ply [0/90/0] square plate with orthotropy ratio (e1/e2=10). table (7) shows nondimensional natural frequency under various uniaxial loads ratio with various thickness ratio (a/h) for simply supported cross-ply [0/90/0] square plate with orthotropy ratio (e1/e2=40). the fundamental frequency decrease when increasing the value of compressive stress until the lowest ibtehal abbas sadiq al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 3444 (2018) 40 natural frequency vanished when inplane stress reaches the critical buckling stress, which proved by other researchers, as shown in fig (3) and fig (4). table 1, non-dimensional natural frequencies of square laminate with(a/h=5), ùúû = ùúü = ý. þ ßû ‚ ùûü =ý. à ßû ‚ áúû = ý. ûà no.of source e1/e2 layers 20 30 40 3d[10] 9.4055 10.165 10.6789 tsdt[11] 9.6265 10.5348 11.1716 fsdt[12] 9.6885 10.6198 11.2708 ppt [4] 9.6252 10.5334 11.1705 present 9.632 10.538 11.173 ansys 9.301 10.07 10.57 3d [10] 9.8398 10.6958 11.2728 tsdt[11] 9.9181 10.8547 11.5012 fsdt[12] 9.9427 10.8828 11.5264 ppt[4] 9.9181 10.8547 11.5009 present 9.925 10.859 11.504 ansys 9.69 10.58 11.16 3d[10] 10.0843 11.0027 11.6245 tsdt[11] 10.0674 11.0197 11.673 fsdt[12] 10.0638 11.0058 11.6444 ppt[4] 10.0671 11.0186 11.6705 present 10.074 11.023 11.673 ansys 10.905 10.84 11.47 table 2, non-dimensional natural frequencies of cross-ply square laminate âúâû =40. no of layer method a/h 10 20 50 100 �0/90�& tsdt [11] 10.56 11.10 11.27 11.30 fsdt [12] 10.47 11.07 11.27 11.29 rpt [4] 10.56 11.10 11.27 11.30 present 10.55 11.10 11.27 11.30 �0/90� tsdt [11] 14.84 16.57 17.18 17.27 fsdt [12] 14.92 16.60 17.18 17.27 rpt [4] 14.84 16.57 17.18 17.27 present 14.85 16.58 17.19 17.29 �0/90�* tsdt [11] 15.46 17.37 18.06 18.16 fsdt [12] 15.50 17.39 18.06 18.17 rpt [4] 15.46 17.37 18.06 18.16 present 15.47 17.38 18.07 18.18 table 3, non-dimensional uniaxial buckling load of simply supported square laminates,(a/h=10), ùúû = ùúü = ý. þ ßû ‚ ùûü = ý. à ßû ‚ áúû = ý. ûà no of layer method ãá diff% 4 fsdt [12] 22.806 rpt [3] 22.57 1.03 present 22.593 0.93 ansys 22.134 2.94 6 fsdt [12] 24.5777 rpt [3] 24.4581 0.48 present 24.483 0.38 ansys 23.78 3.2 10 fsdt [12] 25.45 rpt [3] 25.4225 0.10 present 25.44 0.03 ansys 24.357 4.29 �0/90��0/90�* �0/90�) ibtehal abbas sadiq al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 3444 (2018) 41 table 4, non-dimensional uniaxial buckling load of antisymmetric square laminates ùúû = ùúü = ý. à ßû ‚ ùûü =ý. û ßû ‚ áúû = ý. ûà table 5, non-dimensional biaxial buckling load of antisymmetric cross-ply laminates table 6, dimensionless natural frequency of a laminated plate under buckling different ratio (d). d method fundamental frequency (äá ) 0 [13] 10.649 ansys 10.645 present 10.665 0.25 [13] 9.231 ansys 9.231 present 9.236 0.5 [13] 7.544 ansys 7.544 present 7.541 0.75 [13] 5.379 ansys 5.379 present 5.332 e1/e2=40 e1/e2=25 e1/e2=10 method �ý/åý�æ (0/90) �ý/åý�æ (0/90) �ý/åý�æ (0/90) 21.631 21.601 10.381 10.615 16.301 16.292 8.189 8.317 9.158 9.186 5.746 5.792 [9] present 10 29.965 29.959 11.980 12.065 20.623 20.644 9.153 9.201 10.380 10.424 6.205 6.228 [9] present 20 34.179 34.225 12.601 12.617 22.535 22.583 9.511 9.525 10.843 10.895 6.367 6.382 [9] present 100 e1/e2=40 e1/e2=25 e1/e2=10 method a/h �0/90�' (0/90) �0/90�' (0/90) �0/90�' (0/90) 10.816 10.800 5.190 5.307 8.150 8.146 4.094 4.158 4.579 4.593 2.873 2.896 [9] present 10 14.983 14.979 5.990 6.032 10.311 10.322 4.576 4.600 5.190 5.212 3.102 3.114 [9] present 20 17.090 17.112 6.300 6.308 11.267 11.291 4.755 4.76 5.422 5.447 3.184 3.191 [9] present 100 ibtehal abbas sadiq al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 3444 (2018) 42 table7, non-dimensional natural frequency under various uniaxial loads ratio with various thickness ratio (a/h) for simply supported cross-ply [0/90/0] square plate and orthotropy ratio (e1/e2=40). fig. 3. natural frequency with ratio of buckling load for [0/90/0] simply supported square plate [a/h=10] for different orthotrpy ratio. fig. 4. natural frequency with ratio of buckling load for different layers of simply supported square plate (a/h=10), (e1/e2=40). 4. conclusion natural frequency and buckling stress of simply supported cross-ply square plate subject to initial axial stress have been obtained by using refind plate theory. it is observed good results for natural frequency and critical buckling for uniaxial and biaxial load as compared with other researchers. the following conclusions may be drawn from the present analysis: 1. refined plate theory for analyzing natural frequency and buckling stresses of cross-ply square plate has been presented. it is observed that the natural frequency and buckling load increasing as the number of layer and thickness ratio increases. 2. the buckling stresses can be calculated through the stability equation as eigen value problems. another method to obtain the critical stress of cross-ply plate subject to axial and uniaxial inplane stresses is to compute natural frequency by increasing the absolute value of compressive stress until the lowest natural frequency vanishes. nomenclature symbol discretion units a plate dimension in xdirection m b plate dimension in ydirection m h plate thickness m a¿à ‚ b¿à ‚ d¿à ‚ b¿� extension, bending extension coupling n/m e1, e2, e3 elastic modulus components gp g&g-* , g&* shear modulus components gp a/h=100 a/h=50 a/h=10 a/h=5 ratio of èéê 18.759 18.585 14.78 10.176 0 17.79 17.632 14.02 9.654 0.1 16.77 16.623 13.22 9.102 0.2 15.96 15.550 12.36 8.514 0.3 14.35 14.39 11.44 7.882 0.4 13.26 13.142 10.45 7.195 0.5 11.86 11.754 9.34 6.436 0.6 10.27 10.179 8.09 5.574 0.7 8.38 8.311 6.61 4.551 0.8 5.93 5.877 4.67 3.218 0.9 0 0 0 0 1 ibtehal abbas sadiq al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 3444 (2018) 43 n total number of plate layers n<‚ nb ‚n<b in-plan force result n/m m<� ‚ mb� ‚ m<b� moment result per unit length n.m/m m<� ‚ mb� ‚ m<b� result force per unit length n/m q<=� ‚ qb=� transvers shear force result n qb=� ‚q<=� transfers shear force result n x, y, z cartesian coordinate system m ε< εb ‚ ε= strain components m/m γ<= γb= transvers shear strain m/m σ< σb σ<b σb= σ<= stress components gpa v& v-& poisson's ratio 5. refrences [1] k. swaminathan and d. ragounadin (2004) "analytical solutions using a higher-order refined theory for the static analysis of antisymmetric angle-ply composite and sandwich plates" composite structures, 64, 405-417. [2] s. e. kim, h. t. thai, and lee, j. (2009) ‘buckling analysis of plates using the two variable refined plate theory’, thin-walled structures, 47,455–462. [3] seung-eock kim, et al. 2009 ‘a two variable refined plate theory for laminated composite plates seung-eock’, steel and composite structures, 22, 713–732. [4] h.t.thai, and s.e.kim, 2010 ‘free vibration of laminated composite plates using two variable refined plate theory’, international journal of mechanical sciences. 52, 626–633. [5] h.t.thai, and s.e.kim, 2011 ‘levy-type solution for buckling analysis of orthotropic plates based on two variable refined plate theory’, composite structures. elsevier ltd, 93,1738–1746. [6] hadji, l. et al. 2011 ‘free vibration of functionally graded sandwich plates using fourvariable refined plate theory’, applied mathematics and mechanics, 32,925–942. [7] a. benachour, h. tahar, h. atmane et al. (2011) " a four variable refined plate theory for free vibrations of functionally graded plates with arbitrary gradient" composites part b: engineering,42, 1386-1394. [8] h.t.thai, and s.e.kim, 2012 ‘levy-type solution for free vibration analysis of orthotropic plates based on two variable refined plate theory’, applied mathematical modelling 36, 3870–3882. [9] j.n. reedy, 2004, "mechanics of laminated composite plates and shells: theory and analysis", 2nd ed.; crc press llc. [10] noor ak. free vibrations of multilayered composite plates. aiaa j 1973;11(7):1038–9. [11] reddy jn. mechanics of laminated composite plate: theory and analysis. new york: crc press; 1997 [12] whitney jm, pagano nj. shear deformation in heterogeneous anisotropic plates. j appl mech, trans asme 1970;37(4):1031–6. [13] firas hamzah taya, 2014 "buckling and vibration analysis of laminated composite plates". university of baghdad, mechanical engineering department. )2018( 3444 ، صفحة4د، العد14دجلة الخوارزمي الهندسية المجلمابتهال عباس صادق 44 باستخدام نظرية اللوحة المكررةتحليل االهتزازات تحت تاثير االجهاد االولي **كاني حسين باوة *ابتهال عباس صادق جامعة بغداد / كلية الهندسة قسم الهندسة الميكانيكية /*،** ebtialabas@yahoo.com :البريد االلكتروني * kanihussein1991@gmail.com :البريد االلكتروني ** الخالصة refind)باستخدام نظرية )simply supported( ـيتم الحصول على التردد الطبيعي تحت الضغوط األولية للحصول على صفائح الرقائق المتقاطعة لل plate) سماكة اللوح وتلبي الشروط الحدودية للجر صفر على أسطح الصفيحة عن طريقهذه النظرية مسؤولة عن التوزيع المكافئ لساللة القص المستعرض استخدام حل تحت اإلجهاد األولي باستخدام مبدأ هاملتون ويتم حلها ب eigenدون استخدام عوامل تصحيح القص. يتم اشتقاق المعادالت الحاكمة لمشكلة قيمة )navier ( ـ) لأللواح الطبقية المتناظرة المتماثلة وغير المتماثلة للsimply supported.( تم دراسة تأثير العديد من عوامل التصميم مثل نسبة المعامل (e1 / e2) ونسبة السمك ) (a / h ) وعدد الصفائح (n مقارنة النتائج مع باحثين اخرين.على التردد الطبيعي والضغط على األلواح المحبوسة. تتم final yasin k. salman /al-khwarizmi engineering journal ,vol.1, no. 1,pp 83-100 (2005) ٨٣ al-khwarizmi engineering journal al-khwarizmi engineering journal, vol.1, no.1,pp 83-100, (2005) tthhee eeffffeecctt ooff rreessttrriiccttiioonn sshhaappee oonn llaammiinnaarr nnaattuurraall ccoonnvveeccttiioonn hheeaatt ttrraannssffeerr iinn aa vveerrttiiccaall cciirrccuullaarr ttuubbee dr. yasin k. salman* hhuusssseeiinn aahhmmeedd mmoohhaammmmeedd** nuclear engineering dept,/ college of engineering/ university of baghdad* mechanical engineering dept,/ college of engineering/ university of baghdad** aabbssttrraacctt natural convection heat transfer is experimentally investigated for laminar air flow in a vertical circular tube by using the boundary condition of constant wall heat flux in the ranges of (ral) from (1.1*109) to (4.7*109). the experimental set-up was designed for determining the effect of different types of restrictions placed at entry of heated tube in bottom position, on the surface temperature distribution and on the local and average heat transfer coefficients. the apparatus was made with an electrically heated cylinder of a length (900mm) and diameter (30mm). the entry restrictions were included a circular tube of same diameter as the heated cylinder but with lengths of (60cm, 120cm), sharp-edge and bell-mouth. the surface temperature along the cylinder surface for same heat flux would be higher values for circular restriction with length of (120cm) and would be smaller values for bell-mouth restriction. the results show that the local nusselt number (nux) and average nusselt number )nu( l are higher for bell-mouth restriction and smaller values for (120cm) restriction. for all entry shape restrictions, the results show that the nusselt number values increases as the heat flux increases. from the present work an empirical correlations were obtained in a form of (log lnu ) versus (log lra ) for each case investigated and obtained a general correlation for all cases which reveals the effect of restriction existence on the natural convection heat transfer process in a vertical circular tube. keyword: restriction shape, laminar natural convection, heat transfer, vertical circular tube. iinnttrroodduuccttiioonn thermal convection heat transfer is the process by which heat transfer takes place between a solid surface and the fluid surrounding it. if the motion of fluid is due to solely to the action of buoyancy forces arising from the density variations in the fluid owing to the temperature difference between the fluid and the contacting surface, this case called free convection. if the motion of the fluid is caused by forces independent of the temperature differences in the fluid, arising from externally imposed pressure differences, this case called as forced convection. the available work on natural convection from the inside surfaces of vertical tubes open at both ends with restriction at entry is very limited. it is only recently that this case has attracted attention due to the use of this tube in practical fields including the storage of cryogenic fluids, petroleum storage vessels on hot days, the thermal response of building to a change in environment temperature, yasin k. salman /al-khwarizmi engineering journal ,vol.1, no. 1,pp 83-100 (2005) ٨٤ and the storage of hot fluids for solar power plants and nuclear engineering. in all these cases, the heat loss from or to the tube is an important problem. extensive analytical and experimental work has been conducted with fluids in a tube subject to different boundary conditions, but the specific problem that will be considered here is that of constant wall heat flux. however, most of the available investigations are theoretical and deal with the vertical tube in special cases only. to the author knowledge no work is available on the case, which studied in the present work. the present work has been carried out in an attempt to fill a part of the existing gap. it provides experimental data on uniformly heated constant wall heat flux in vertical tube. dyer, j.r. (1968) conducted theoretical and experimental works for natural convection heat transfer from the inside surface of a vertical cylinder in the isothermal and constant wall heat flux conditions. he assumed that the incompressible flow is laminar, that the fluid approaching the entrance of the cylinder has a flat velocity profile, that the flow was symmetrical about the vertical axis of the cylinder and the properties of the fluid vary insignificantly with temperature except the density. the results obtained were plotted in the form of (lognur) against (loggrr.pr.r/l) for the isothermal cylinder and in the form of (lognur) against (loggrr.pr.nur.r/l) for the constant heat flux cylinder. he also made some experiments on an isothermal cylinder of (25mm) inside diameter and (1220mm) length in the range of (grr.pr.r/l) from (8 to 80). the results obtained were compared with the theoretical results. dyer, j.r. (1970) investigated theoretically the development of laminar natural convective air flow in heated vertical ducts that are restricted at the bottom with (ra) ranges from (6 to 84). the governing equations (continuity, momentum and energy) were solved numerically by finite difference method. from this work, relationship between (nu) versus (ra) and axial temperature distribution were presented. kageyama, m. and izumi, r. (1971) solved numerically by finite difference method natural heat convective fields in the entrance region of a heated vertical circular tube, in which the temperature and velocity profiles were developing simultaneously and the characteristics of heat transfer were obtained. the analysis presented was based on the assumption that the inlet velocity profile is uniform. analytical and numerical verifications are given for uniform wall temperature and for both infinite and semi-infinite pipe lengths. davis, l.p. and perona, j.j (1974) used a finite difference method to solve the incompressible thermal boundary layer equations for air flow by natural convection in a vertical tube having conditions of constant wall temperature and constant wall heat flux. air enters the bottom of the tube with uniform velocity and temperature flows upward through the tube due to natural convection. the flow is assumed to be both stable and laminar. the velocity and temperature profiles were obtained for various stages of the flow development, a graphical correlation was found between dimensionless tube length and two dimensionless quantities representative of the volumetric flow rate and the rate of heat dissipation. comparison was made with available theoretical investigations and showed excellent agreement. meric, r.a. (1976) analyzed the development of free convection in yasin k. salman /al-khwarizmi engineering journal ,vol.1, no. 1,pp 83-100 (2005) ٨٥ finite vertical tubes by an analytical method, which is based upon a slug flow linearization of the governing boundarylayer type equations. the resulting equations are solved by means of laplace transformations to give simple closed form expression for the flow variables. the variation of inlet velocity with (gr), velocity and temperature profiles for (pr=0.7) were depicted, also the fluid pressure distribution and heat flux versus tube length were presented. the results were also compared with available numerical results and showed good agreement. barrow, r.d. (1978) investigated theoretically and experimentally upward free convection for air (pr=0.7) in an internally heated vertical duct open at both ends. the experimental data for the wall temperature distribution and local heat transfer coefficient were compared with the results of numerical analysis of an idealized and laminar flow heat transfer model. correlations for the average nusselt number, maximum wall temperature and flow rate were presented with the rayleigh number as the independent variable. dyer, j.r. (1983) presented a theoretical and experimental study of natural convective for a laminar air flow in heated vertical ducts. the ducts were open – ended, circular in cross section and their internal surfaces dissipate heat uniformly. temperature and velocity fields and the relationship between (nu) and (ra) numbers were obtained by solving the governing equations by a stepbystep numerical technique. two (ra) numbers were introduced, one expressed in terms of the uniform heat flux and the other in terms of the mean wall temperature. the influence of (pr) number on the relationship between (nu) and (ra) was discussed. also, experiments were conducted for (ra) between (1 to 13000). three ducts were used having same length of (1.22m) but of different internal diameter of (19.1, 25.4, and 46.7mm). from the experiments (nu) number was determined with air as the working fluid. comparison between experimental and theoretical studies was carried out and showed good agreement. kokugan, t. and kinoshita, t. (1985) performed experimental work in a heated vertical open ends tube consisting of heated section at constant wall temperature. correlations between (gr) and (re) were derived by setting up a mechanical energy balance in the tube. the following equation was obtained semi-empirically in the experimental conditions: )re.d/()ll(2.3re3.6gr ooh 2 oo ++= ….(1) where: lh =heated length; lo= entrance length and subscript (o) denoted to at room temperature. the results were compared with available numerical results obtained by (davis et al, 1971). hess, c.f. and miller, c.w. (1989) carried out experiments using a laser doppler velocimeter (ldv) to measure the axial velocity of a fluid contained in a cylinder subject to constant heat flux on the side walls. the modified rayleigh numbers ranged between (4.5*109) to (6.4*1010), which corresponds to the upper limit of the laminar regime. the flow field inside the boundary layer was divided into three regions along the axis of the cylinder and a parabolic distribution was used to fit the data within each region. variation of axial velocity with radius for different height in the bottom and top parts of the cylinder and inside the boundary layer region and with radius for different time were presented. also, the variation of radial position of maximum velocity and radial position of zero velocity with rayleigh number yasin k. salman /al-khwarizmi engineering journal ,vol.1, no. 1,pp 83-100 (2005) ٨٦ was depicted. excellent agreement was found with an available numerical solution. al-arabi, m. et al (1991) investigated experimentally natural convection heat transfer from the inside surfaces of vertical tube to air in the ranges of (grl.pr) from (1.44*107) to (8.85*108) and (l/d) ranged from (10 to 31.4). the results obtained were correlated by dimensionless groups as follows: 25.0 ml ism ml pr)gr( )]tt(05.01[ 11.1nu −+ = …… (2) in this study, the effect of (l/d) on (numl) was insignificant and the entrance length was practically constant. the results were compared with the available theoretical data of (dyer, 1975) and showed a good agreement. wu, yissu (1995) examined numerically and experimentally the problem of laminar natural convection in vertical tubes with one end open to a large reservoir, designated open thermosyphons, and to predict flow behavior and the heat transfer rates. in the numerical study, a semi-implicit, time-marching, finite -volume solution procedure was adopted to solve the three governing equations--mass, momentum, and energy--sequentially. experimental work involved the use of a mach-zehnder interferometer to examine the temperature field for a modified rectangular open thermosyphons through the interpretation of fringe patterns. these experimental fringe patterns were used for the qualitative comparison with those obtained from the numerical analyses. nusselt numbers were determined from the interferometer results and compared with numerical results. heat transfer rates through the tube wall were found to be strong functions of the tube radius, and approached an asymptotic limit as the tube radius was increased. both experimental and numerical results exhibited an oscillatory nature for large height-to-width (aspect ratio) open cavities. comparisons between experimental and numericallygenerated fringe patterns indicated good agreement. the purpose of the present investigation is to determine experimentally the effect of entry restriction lengths and shapes placed in bottom position of a uniformly heated vertical circular tube on the laminar air flow due to natural convection heat transfer process and to obtain general correlation for this problem. experimental apparatus the experimental apparatus which was designed to have a heated section preceded with entry restrictions having different shapes and lengths, as well as, different grashof number is shown schematically in fig. (1a), to investigate natural convection heat transfer in a vertical circular tube. the apparatus consists essentially of a cylindrical heated section open at both ends, mounted vertically on a wooden board and the lower end of the restriction shape is protected from outside air currents by shields. the heated cylinder (1) provided with changeable entry restrictions of four different shapes, particulars of which are: cylindrical restrictions with lengths of (60cm, 120cm), sharp-edge restriction and bell-mouth restriction. the air was withdrawn from atmosphere flows due to buoyancy effect through the entry restriction into the heated section and then the heated air was exhausted to the atmosphere. the heated cylinder (1) is made of copper with (30mm) inside diameter, and (900mm) length. the teflon connection pieces: represents a part of the test section yasin k. salman /al-khwarizmi engineering journal ,vol.1, no. 1,pp 83-100 (2005) ٨٧ inlet and another teflon piece represents the heated section exit. the entry restrictions are connected with the heated cylinder by teflon connection piece bored with the same inside diameter of the (heated cylinder and entry restriction). the teflon was chosen because of its low thermal conductivity in order to reduce the test section ends losses. the cylinder is heated electrically by using an electrical heater as shown in fig. (1b). it consists of nickel-chrome wire (3) electrically isolated by ceramic beads, wounded uniformly along the cylinder as a coil in order to give uniform heat flux. an asbestos rope was used as spacer to secure the winding pitch. the outside of the test section was then thermally insulated by asbestos (4) and fiberglass (5) layers, having thicknesses of (15) mm and (16) mm respectively. twenty (0.2mm)-asbestos sheath copperconstantan (type t) thermocouples (2), to measure the cylinder surface temperatures were fixed along the cylinder. the thermocouples (2) were fixed by drilling twenty holes (2) and along the cylinder wall. the measuring junctions were secured permanently in the holes by sufficient amount of high temperature application defcon adhesive. all thermocouples were used with leads and calibrated using the melting points of ice made from distilled water as reference point and the boiling points of several pure chemical substances. the inlet bulk air temperature was measured by one thermocouple placed in the beginning of the entry restriction, while the outlet bulk air temperature was measured by three thermocouples located in the heated section exit. the local bulk air temperature was calculated by fitting straight line interpolation between the measured inlet and outlet bulk air temperatures. to perform heat loss calculation through the heated section lagging, six thermocouples are inserted in the lagging (6) as two thermocouples at three stations along the heated section as shown in fig. (1b). by using the average measured temperatures and thermal conductivity of the lagging, the heat loss through lagging can be determined. also, to evaluate the heat losses from the ends of the heated section, two thermocouples were fixed in each teflon piece. by knowing the distance between these thermocouples and the thermal conductivity of the teflon, the end losses could be calculated. voltage regulator (variac), accurate ammeter and digital voltmeter were used to control and measure the input power to the working cylinder. the apparatus was allowed to turn on for at least (3 hours) before the steady state conditions were achieved. the readings of all thermocouples were recorded every half an hour by a digital electronic thermometer until the reading became constant, then the final reading was recorded. the input power to the heater could be changed to cover another run in shorter period of time and to obtain steady state conditions for next heat flux. data reduction method the following simplified steps were used to analyze the natural convection heat transfer process for air flow in a vertical circular tube when its surface was subjected to a constant wall heat flux boundary condition. the total input power supplied to cylinder can be calculated as: i * v q t = ……….. (3) the convection heat transferred from the cylinder surface: .condtconv. q q q = ……… (4) where qcond. = is the total conduction heat losses (lagging and ends losses), yasin k. salman /al-khwarizmi engineering journal ,vol.1, no. 1,pp 83-100 (2005) ٨٨ and its calculated from       ∆ = th .cond r tq , where rth is the thermal resistance of the insulations. the convection heat flux can be represented by: sa q q .conv .conv = …… (5) where as = π *d*l the convection heat flux, was used to calculate the local and average heat transfer coefficient as follows: bxsx .conv x tt qh − = …… (6) where: tsx = local surface temperature. tbx = local bulk air temperature. all the air properties were evaluated at the mean film temperature (louis burmeister, 1993). 2 ttt bxsx fx + = ……. (7) where: tfx= local mean film air temperature. the local nusselt number (nux) can be determined as: k l.h nu x x = ……. (8) the average values of nusselt number )nu( l can be calculated based on the calculated average surface temperature and average bulk air temperature as follows: ∫ = = = lx 0x sxs dxt l 1t …….. (9) ∫ = = = lx 0x bxa dxt l 1t ……. (10) 2 tt t as f + = ………. (11) the average values of the other parameters can be calculated as follows: )( . as conv ttk lq nu l − = …. (12) 2 as 3 )tt(lg gr l ν −β = …… (13) pr*grra ll = ………. (14) where: )t273( 1 f+ =β , all the air physical properties ( κνµρ and,, ) were evaluated at the average mean film temperature ( ft ), but all the physical properties in all papers which listed in references were taken at a mean film temperature which based on ambient temperature at tube entrance and given by [tmf =(tms+ti) /2]. results and discussion a total of (28) test runs were conducted to cover (four) entry restrictions with different lengths and shapes of two circular tube with length [60cm (l/d=20) and 120cm (l/d=40), sharp-edge and bell-mouth]. the range of used heat fluxes was (249 w/m2 to 1000 w/m2). surface temperature generally, many variables such as heat flux, and the flow restriction situation may affect the variation of the surface temperature along the cylinder. the temperature variation for selected runs is plotted in figs. (3 6). the variation of the surface temperature (ts), with tube length is shown in fig. (2) for different heat fluxes. the (ts-x) curves for all restriction shapes have the same general shape. the value of (ts) gradually increases with length until a limit beyond which it begins to decrease. this phenomena, which can be explained if fig. (2) is considered. at the entrance to the tube (point a) the thickness of the boundary layer is zero. yasin k. salman /al-khwarizmi engineering journal ,vol.1, no. 1,pp 83-100 (2005) ٨٩ then it gradually increases until, at (point b), the boundary layer fills the tube. from (point a) to (point b) the heat transfer gradually decreases and (ts) gradually increases. beyond (point b) one would expect a straight-line (tsx) relation (bc) the case being that of constant wall heat flux. however, as the air is heated along the tube, its physical properties gradually change with the increased temperature. the thermal conductivity increases causing less resistance to the flow of heat and the viscosity increases causing radial flow of the hotter layers of air nearer to the surface to the tube center. a gradual increase of the local heat transfer beyond (point b) must then result. for constant wall heat flux this can only take place if the local difference between the bulk air temperature (as shown by straightline ca ′′ ) and the surface temperature decreases resulting in the shape of the (ts-x) curve ( cab ′ ) shown. fig. (3) shows the variation of the surface temperature along the cylinder for different heat fluxes, for restriction with length of 60cm (l/d=20). this figure reveals that the surface temperature increases at cylinder entrance to reach a maximum value after which the surface temperature decreases. the location of maximum temperature seems to move toward the cylinder entrance as the heat flux increases. this can be attributed to the developing of the thermal boundary layer faster due to buoyancy effect as the heat flux increases, and as explained previously. fig. (4) is similar to fig. (3) but pertains to restriction with length of 120cm (l/d=40). the curves in the two figures show same trend, but the surface temperature values in fig. (4) are higher than values in fig. (3) due to the length of restriction. figs. (5&6) are similar in trends to figs. (3&4) but pertains to restrictions of sharp-edge and bell-mouth respectively. figs. (7&8) show the effect of variation of restriction shape on the cylinder surface temperature for low heat flux (249 w/m2) in fig. (7) and for high heat flux (996 w/m2) in fig. (8). it is obvious from these figures that the increasing of restriction length causes an increase of the surface temperature, compared to the case as the heat flux kept constant. it is necessary to mention that the friction between the inside surface of the restriction length and the air flowing through it caused the temperature at entrance to the heated tube to be higher than the ambient temperature. also, in these figures the lower values of the cylinder surface temperature takes place in bell-mouth restriction because the turbulence is smaller in the sharpedge restriction. local nusselt number (nux) for natural convection from a uniformly heated surface of length (l) exposed directly to the atmosphere, the mean heat transfer coefficient for the whole length is calculated from: ∫ = = = lx 0x xm dxh l 1h where: bxsx x tt q t qh − = ∆ = (δt) in above equation is taken as the difference between that local surface temperature (tsx) and the air temperature far away the effect of the surface. all previous investigators written in introduction section calculated the heat transfer coefficient based on the temperature difference between the surface temperature and the fluid temperature at the entrance (ti) [i.e. (δt)= (tsx-tbi)]. in the present work, the heat transfer surface is not exposed to the atmosphere (because the flow is confined). heat is transferred from the hot surface of the cylinder to the air flowing in it. yasin k. salman /al-khwarizmi engineering journal ,vol.1, no. 1,pp 83-100 (2005) ٩٠ therefore, (δt)x cannot be taken equal to (ts-ti). it should be taken as (tsxtbx) where (tbx) is the local bulk air temperature in the cylinder. the variation of the local nusselt number (nux) with the dimensionless axial distance (x/d), is plotted for selected runs in figs. (9 14). figs. (9-12) show the effect of the heat flux variation on the (nux) distribution for the four restriction shapes used in the present work respectively. it is clear from these figures that at the higher heat flux, the results of (nux) were slightly higher than the results of lower heat flux. this may be attributed to the secondary flow effect that increases as the heat flux increases leading to higher heat transfer coefficient. therefore, as the heat flux increases, the fluid near the wall becomes hotter and lighter than the bulk fluid in the core. as a consequence, two upward currents flow along the sides walls, and by continuity, the fluid near the cylinder center flows downstream. figs. (13&14) show the effect of variation of restriction shape on the (nux) distribution with (x/d), for low heat flux (249 w/m2) in fig. (13) and for high heat flux (996 w/m2) in fig. (14). for constant heat flux, the (nux) values give higher results in bellmouth restriction than the lower values in (l/d=40) restriction. this situation reveals that in bell-mouth the velocity of flow is uniform and the intensity of turbulence is smaller but in sharp-edge restriction there is extra turbulence at the tube entrance as a result of which the effect of viscosity becomes negligible, causes the heat transfer results to be lower than in bell-mouth restriction. but in the restrictions with lengths of (l/d=20 and l/d=40) the velocity profile in this condition will be fully developed at tube entrance that may be becomes as a resistance on the flow and as (l/d) is higher the resistance becomes higher and the surface temperature will be higher, this causes that the (nux) values will be lower than the other restriction shapes. average nusselt number )nu( l the variation of the average nusselt number )nu( l with the dimensionless axial distance (x/d) is depicted for selected runs in figs. (15 18). figs. (15&16) show the effect of the heat flux variation on the )nu( l for restrictions with lengths of (l/d=20 and l/d=40) respectively and the effect of variation of restriction shapes on the )nu( l for low heat flux (249w/m2) and high heat flux (996w/m2) in figs. (17&18) respectively. the )nu( l variations for all restriction shapes are similar trend mentioned for (nux). average heat transfer correlation the general correlation obtained from dimensional analysis (ede, a.j., 1967) for heat transfer by natural convection is: n 1 )ra( f nu = ……… (15) in the case of heat transfer from the inside surface of vertical cylinders one expects that there is an effect of both length and diameter. for similarity with flat surface (which is a cylinder of infinite diameter) the characteristic linear dimension in (nu and gr) may be taken as the tube length (l). then equation (15) becomes: n 2l )ra( f nu = ……… (16) therefore, the following correlations were obtained from the present work for each restriction shape and obtained a general correlation for all restriction shapes as follows, and it shown in figs. (19 23): yasin k. salman /al-khwarizmi engineering journal ,vol.1, no. 1,pp 83-100 (2005) ٩١ 0.23 ll )ra( 1.176 nu = for restriction with (l/d=40) ………. (17) 0.23 ll )ra( 1.206 nu = for restriction with (l/d=20) …….. (18) 0.23 ll )ra( 1.372 nu = for sharp-edge restriction .......... (19) 0.23 ll )ra( 1.462 nu = for bellmouth restriction ……... (20) 0.23 ll )ra( 1.248 nu = for all restriction shapes ……… (21) as a comparison between the present study and with the normal case, which included vertical cylinder open at both ends without any type of restriction in the laminar range, the correlation obtained for the normal case was (louis berimester, 1993): 0.25 ll )ra( 59.0 nu = …… (22) from the comparison, it is clear that the restriction shape and length has a tremendous effect on the heat transfer results. conclusions as a result of the experimental work conducted in the present investigation to study natural convection heat transfer from the inside surface of uniformly heated vertical circular tube with different restriction shapes placed inside in bottom sections, the following conclusions can be made: the surface temperature increases as the heat flux increases. for the same heat flux the surface temperature for restriction of (l/d=40) is higher than that for other restriction shapes. the variation of (nux) with (x/d), for all restriction shapes has the same trend and this variation is summarized as follows: for all restriction shapes, the (nux) increases with the increase of heat flux, for the same heat flux the (nux) for bell-mouth restriction is higher than for other restriction shapes. correlations in the form of (log lnu ) against (log lra ) (using cylinder length as the characteristic linear dimension) represent the results for each restriction shape [eqs. (17-20)]. also, a general correlation for all restriction shapes, which connects all the results [eq. (21)]. from the comparison, the restriction shape and length has a tremendous effect on the heat transfer results. references al-arabi, m.; khamis, m. and abd-ulaziz, (1991) ”heat transfer by natural convection from the inside surface of a uniformly heated vertical tube”. int. j.heat and mass, vol.34, no.4/5, pp.1019-1025. barrow, r.d., (1978) ”heat transfer by free convection in open ended vertical duct”. int. heat transfer conference, 5th proc., tokyo, vol.3, paper no.nc2.5, pp.59-63. davis, l.p. and perona, j.j., (1974) ” development of free convection flow of a gas in a heated vertical open tube ”. int. j. heat and mass transfer, vol.14, pp.889-903. dyer, j.r., (1968)”natural convective flow through a vertical duct with a restricted entry ”. int. j. heat and mass transfer, vol.21, no.10, pp.1341-1354. dyer, j.r., (1970) ”the development of laminar natural convective flow in a vertical duct of circular crosssection that has a flow restriction at the bottom”. int. heat transfer conference, 4th proc., paris, vol. iv, paper no.nc2.8, pp.1-11. dyer, j.r., (1983) ”the development of laminar natural convective flow in a vertical uniform heat flux duct ”. int. j. heat and mass transfer, vol.18, pp.1455-1465. yasin k. salman /al-khwarizmi engineering journal ,vol.1, no. 1,pp 83-100 (2005) ٩٢ ede, a.j., (1967) “ an introduction to heat transfer”. pergamon press, london. hess, c.f. and miller, c.w., (1989) ” natural convection in a vertical cylinder subject to constant heat flux”. int. j. heat and mass transfer, vol.22, no.3, pp.421430. kageyama, m. and izumi, r., (1971) ” natural convection in a vertical circular tube ”. bull. j. s.m.e., vol.13, no.57, pp.382-394. kays, w.m. and london, a.l., (1984) ”compact heat exchangers” tech. report 23, stanford university. kokugan, t. and kinoshita, t., (1985) ”natural convection flow rate in a heated vertical tube ”. journal of the chemical engineering of japanese, vol. 8,no.6, pp.445-450. louis c. burmeister, (1993) “convective heat transfer “. john wiley&sons, inc., 2nd edition. meric, r.a., (1976) “an analytical study of natural convection in a vertical open tube”. int. j. heat and mass transfer, vol.20, pp.429-431. senthil kumar, r. and rajasekaran, s., (2001) “heat transfer by natural convection”. int. j. heat and mass transfer, vol.12, pp.242-245. (abstract only) wu, yissu (1995) “laminar natural convection in vertical tubes with one end open to a reservoir” j. heat of transfer, vol.12, pp.134-154. (abstract only) yasin k. salman /al-khwarizmi engineering journal ,vol.1, no. 1,pp 83-100 (2005) ٩٣ nomnclature as = cylinder surface area, (m2). dimensionless group cp= specific heat at constant pressure, (j/kg.°c). gr=grashof number=g β l3(ts-ta)/ν 2 d =cylinder diameter, (m). nu =nusselt number = h.l / k g =gravitational acceleration, (m/s2). pr = prandtl number = µ . cp/k h =heat transfer coefficient, (w/m2.°c). ra= rayleigh number = gr.pr i =heater current, (ampere). x/d= axial distance k =thermal conductivity, (w/m.°c). l =cylinder length, (m). subscript qcond. =conduction heat loss, (w). a air qconv. = convection heat flux, (w/m2). b bulk qconv. =convection heat loss, (w). f film qt =total heat input, (w). i inlet r=cylinder radius, (m). m mean t =air temperature, (°c). s surface v=heater voltage, (volt). l based on tube length x =axial distance, (m). t total greek w wall x local β thermal expansion coefficient, (1/k). superscript µ dynamic viscosity, (kg/m.s). ν kinematic viscosity, (m2/s). ρ air density, (kg/m3). average yasin k. salman /al-khwarizmi engineering journal ,vol.1, no. 1,pp 83-100 (2005) ٩٤ fig. (1a) layout of experimental arrangement air in air out 1 2 3 4 5 6 7 1mixing chamber 2thermocouples 3inlet teflon piece 4-heated section 5exit teflon piece 6different restriction shapes 7shields 30 cm fig. (1b) general arrangement of experimental apparatus 1tube 2surface thermocouples 3electrical heater 4asbestos layer 5fiberglass layer 6thermocouples of lagging yasin k. salman /al-khwarizmi engineering journal ,vol.1, no. 1,pp 83-100 (2005) ٩٥ 0.1 0.3 0.5 0.7 0.90.0 0.2 0.4 0.6 0.8 1.0 x (m) 50 70 90 110 130 150 60 80 100 120 140 160 t s ( c ) q= 249 w/m^2 q= 389 w/m^2 q= 762 w/m^2 q= 996 w/m^2 o 0.1 0.3 0.5 0.7 0.90.0 0.2 0.4 0.6 0.8 1.0 x (m) 50 70 90 110 130 150 170 40 60 80 100 120 140 160 180 t s ( c ) q= 249 w/m^2 q= 389 w/m^2 q= 762 w/m^2 q= 996 w/m^2 fig. (3) variation of surface temperature versus axial distance for restriction of (l/d= 20) fig. (4) variation of surface temperature versus axial distance for restriction of (l/d= 40) ts(c) bulk air temperature surface temperature b c c ′′ c′ x(m) a fig. (2) variation of surface temperature versus axial distance along the tube yasin k. salman /al-khwarizmi engineering journal ,vol.1, no. 1,pp 83-100 (2005) ٩٦ 0.1 0.3 0.5 0.7 0.90.0 0.2 0.4 0.6 0.8 1.0 x (m) 50 70 90 110 130 150 40 60 80 100 120 140 160 t s ( c ) q= 249 w/m^2 q= 389 w/m^2 q= 762 w/m^2 q= 996 w/m^2 fig.(5) variation of surface temperature versus axial distance for sharp-edge restriction 0.1 0.3 0.5 0.7 0.90.0 0.2 0.4 0.6 0.8 1.0 x ( m ) 50 70 90 110 130 150 40 60 80 100 120 140 160 t s ( c ) q= 249 w/m^2 q= 389 w/m^2 q= 762 w/m^2 q= 996 w/m^2 fig. (6) variation of surface temperature versus axial distance for bell-mouth restriction fig. (7) variation of surface temperature versus axial distance for different restriction shapes for q= 249 w/m2 fig. (8) variation of surface temperature versus axial distance for different restriction shapes for q= 966 w/m2 0.1 0.3 0.5 0.7 0.90.0 0.2 0.4 0.6 0.8 1.0 x ( m ) 58 62 66 70 74 78 82 86 56 60 64 68 72 76 80 84 t s ( c ) (l/d=40) restriction (l/d=20) restriction sharp-edge restriction bell-mouth restriction 0.1 0.3 0.5 0.7 0.90.0 0.2 0.4 0.6 0.8 1.0 x (m) 90 110 130 150 80 100 120 140 160 t s ( c ) o (l/d=40) restriction (l/d=20) restriction sharp-edge restriction bell-mouth restriction yasin k. salman /al-khwarizmi engineering journal ,vol.1, no. 1,pp 83-100 (2005) ٩٧ fig. (11) variation of local nusselt number versus axial distance for sharp-edge restriction fig. (12) variation of local nusselt number versus axial distance for bell-mouth restriction fig. (9) variation of local nusselt number versus axial distance for restriction of (l/d=20) fig. (10) variation of local nusselt numbeversus axial distance for restrictio of (l/d=40) 7 8 9 2 3 4 5 6 7 8 9 2 3 4 1 10 x/d 25 75 125 175 225 275 325 375 0 50 100 150 200 250 300 350 400 n ux 7 8 9 2 3 4 5 6 7 8 9 2 3 4 1 10 x/d 25 75 125 175 225 275 325 0 50 100 150 200 250 300 350 n ux 7 8 9 2 3 4 5 6 7 8 9 2 3 4 1 10 x/d 25 75 125 175 225 275 325 375 0 50 100 150 200 250 300 350 400 n ux 7 8 9 2 3 4 5 6 7 8 9 2 3 4 1 10 x/d 25 75 125 175 225 275 325 375 425 0 50 100 150 200 250 300 350 400 n ux yasin k. salman /al-khwarizmi engineering journal ,vol.1, no. 1,pp 83-100 (2005) ٩٨ 7 8 9 2 3 4 5 6 7 8 9 2 3 41 10 x/d 175 225 275 325 375 150 200 250 300 350 7 8 9 2 3 4 5 6 7 8 9 2 3 41 10 x/d 35 45 55 65 75 85 95 105 30 40 50 60 70 80 90 100 110 fig. (17) variation of average nusselt number versus axial distance for different restriction shapes fig. (18) variation of average nusselt number versus axial distance for different restriction shapes lnu lnu fig. (19) a correlation between average nusselt number versus average rayleigh number for (l/d=40) restriction fig. (20) a correlation between average nusselt number versus average rayleigh number for (l/d=20) restriction 9.42 9.46 9.50 9.54 9.589.44 9.48 9.52 9.56 log (ral) 1.50 1.70 1.90 2.10 2.30 2.50 2.70 2.90 1.40 1.60 1.80 2.00 2.20 2.40 2.60 2.80 3.00 l og (n ul ) 9.42 9.46 9.50 9.549.44 9.48 9.52 log (ral) 1.50 1.70 1.90 2.10 2.30 2.50 2.70 2.90 1.40 1.60 1.80 2.00 2.20 2.40 2.60 2.80 3.00 l og (n ul ) 23.0 ll )ra(202.1nu = 23.0 ll )ra(176.1nu = yasin k. salman /al-khwarizmi engineering journal ,vol.1, no. 1,pp 83-100 (2005) ٩٩ 9.38 9.42 9.46 9.50 9.549.40 9.44 9.48 9.52 9.56 log (ral) 1.30 1.50 1.70 1.90 2.10 2.30 2.50 2.70 2.90 1.40 1.60 1.80 2.00 2.20 2.40 2.60 2.80 3.00 l og (n ul ) 9.42 9.46 9.50 9.549.44 9.48 9.52 9.56 log (ral) 1.55 1.65 1.75 1.85 1.95 2.05 2.15 2.25 2.35 2.45 2.55 2.65 2.75 1.50 1.60 1.70 1.80 1.90 2.00 2.10 2.20 2.30 2.40 2.50 2.60 2.70 2.80 l og (n ul ) fig. (21) a correlation between average nusselt number versus average rayleigh number for sharp-edge restriction fig. (22) a correlation between average nusselt number versus average rayleigh number for bell-mouth restriction 9.38 9.42 9.46 9.50 9.54 9.589.40 9.44 9.48 9.52 9.56 log (ral) 1.00 1.40 1.80 2.20 2.60 3.00 3.40 3.80 1.20 1.60 2.00 2.40 2.80 3.20 3.60 l og (n ul ) fig. (23) a correlation between average nusselt number versus average rayleigh number for all restriction shapes 23.0 ll )ra(372.1nu = 23.0 ll )ra(462.1nu = 23.0 ll )ra(248.1nu = yasin k. salman /al-khwarizmi engineering journal ,vol.1, no. 1,pp 83-100 (2005) ١٠٠ تأثير شكل المقيد على انتقال الحرارة الطباقي بالحمل الطبيعي في انبوب دائري شاقوليتأثير شكل المقيد على انتقال الحرارة الطباقي بالحمل الطبيعي في انبوب دائري شاقولي **حسين احمد محمدحسين احمد محمد *ياسين خضير سلمانياسين خضير سلمان. . دد جامعة بغدادجامعة بغداد//كلية الهندسةكلية الهندسة//نوويةنوويةقسم الهندسة القسم الهندسة ال** جامعة بغدادجامعة بغداد//كلية الهندسةكلية الهندسة//قسم الهندسة الميكانيكيةقسم الهندسة الميكانيكية**** ::الخالصةالخالصة انتقال الحرارة بالحمل الطبيعي لجريان الهواء الطباقي في داخل أنبوب دائري شـاقولي باسـتخدام ُبحث عملياً صمم الجهاز العملي ). 4.7ُ 10*٩(إلى ) 1.1 109*(من ) ral(شرط ثبوت الفيض الحراري ولمدى تغير رقم رايـلي الموضوع في مدخل األنبوب وفـي الموقـع السـفلي ألنبـوب ) restriction(إليجاد تأثير األنواع المختلفة من المقيد . على درجة الحرارة على طول سطح األنبوب المسخن وكذلك على معامل انتقال الحرارة المـوقعي و المعـدل , التسخين مقيـدات ). 30mm(وبقطر داخلـي ) 900mm(الجهاز العملي المستخدم يتكون من اسطوانة مسخنة حرارياً بطول وكذلك , )120cm, 60cm(ل تتضمن أنبوب دائري أسطواني له نفس القطر الداخلي ألنبوب التسخين ولكن بأطوالالدخو ). bell-mouth( فم الجرس باإلضافة إلى مقيد بشكل (sharp-edge)حادة حافة مقيد بشكل لى مـا يمكـن للمقيـد لقد وجد من خالل النتائج العملية أن درجة الحرارة على طول سطح االسطوانة تكون أع عند نفس ) bell-mouth( فم الجرس وتكون اقل ما يمكن في حالة المقيد الذي بشكل) 120cm(األسطواني الذي طوله )nu( والمعدل) nux(أظهرت النتائج أن قيم رقم نسلت الموقعي . الفيض الحراري l تكون أعلى ما يمكن في حالة المقيد وأيضـا , ) 120cm(وتكون اقل ما يمكن في حالة المقيد األسطواني الذي طوله ) bell-mouth( لجرسفم االذي بشكل لقـد تـم الحصـول علـى معـادالت . بينت النتائج زيادة رقم نسلت كلما زاد الفيض الحراري ,لكل الحاالت المستخدمة (بشكل ) empirical correlations(تجريبية lnu (log دض )lra log( لكل حالة من الحـاالت المدروسـة فـي البحث وكذلك تم الحصول على معادلة عامة والتيُ تظهر تأثير وجود المقيد على عملية انتقال الحرارة بالحمل الطبيعي في .داخل أنبوب دائري شاقولي <4d6963726f736f667420576f7264202d2036382d203830d2ede4c820e6e3cde3cf20e6e4c8c7> al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 14, no. 3, september, (2018) p.p. 6880 experimental study on doweled expansion joints on behavior for plain concrete pavement system zainab ahmed al-kaissi* mohammed hashim mohammed** nabaa sattar kareem*** *,**,***department of highways and transportation engineering/ al-mustansiriyah university *email: zainabalkaisi77@googlemail.com **email: m_sahlani@yahoo.com ***email: eng.nabaa1992@gmail.com (received 26 april 2017; accepted 7 march 2018) https://doi.org/10.22153/kej.2018.03.001 abstract this paper deals with load-deflection behavior the jointed plain concrete pavement system using steel dowel bars as a mechanism to transmit load across the expansion joints. experimentally, four models of the jointed plain concrete pavement system were made, each model consists of two slabs of plain concrete that connected together across expansion by two dowel bars and the concrete slab were supported by the subgrade soil. two variables were dealt with, the first is diameter of dowel bar (12, 16 and 20 mm) and the second is type of the subgrade soil, two types of soil were used which classified according to the (aashto): type i (a-6) and type ii (a-7-6). experimental results showed that increasing dowel bar diameter from 12 mm to 20 mm has a little effect on load-deflection behavior of the tested specimens with only 5% increase in failure load. this may be attributed to that the failure (caused by flexural crack) depends mainly on concrete strength. results also showed that decreasing cbr value of subgrade soil from 7% to 5% decreases failure load by about 33%. keywords: steel dowel bars, jointed plain concrete pavement, load-deflection behavior, subgrade soil. 1. introduction a rigid pavement system consists of a number of concrete slabs. the concrete slabs are limited in width and length. the slabs rest on the subgrade only or subgrade and subbase but in some cases the slabs resting on subgrade, subbase and base layer. in the rigid pavement system, joints installed to supply space to accommodate horizontal movement of slab due to moisture and temperature change, and to control cracks. the pavement system requires a device of load transfer like tie bars or dowel bars. the load transfer device efficiently helps to reduce stresses of pavement and decrease deflection of loaded slab by transmit an applied load to the adjacent unloaded slab [1,2,3]. a jointed plain concrete pavement system exposed to the following loading cases: self-weight of the slab, wheel loads of vehicle and loads due to thermal effects of environmental due to temperature and moisture changes which causes crack of the concrete slab, load transfer devices failure like dowel bars, and loss of slab support because of temperature create curling, opening and closing joints [4]. 2. research significance in this paper, the load deflection behaviors of steel dowel bars using experimental methods for various diameter of dowel bars and subgrade soil strength and to achieve a better understanding of the load transfer mechanism. to validate the zainab ahmed al-kaissi al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 6880 (2018) 69 experimental models, the results of the loaddeflection behavior of experimental models are compared with the results of the load-deflection of numerical models. 3. test methodology to simulate the expansion joint in plain concrete pavement system, the wooden mold is made for concrete slab casted. net dimensions of mold are (121 * 60 * 12.5 cm) the models thickness was chosen according to the aci where less pavement thickness of parking lots equal 125 mm according of aci 330r, see table (1). a piece of cork is used to separate the two slabs of plain concrete pavement to represent the joint between them, the cork dimensions are (60 cm) length, (12.5 cm) height and (1 cm) width, which represents the joint width (because these joint width is typical for expansion joints in the middle-eastern countries like iraq [15]). thus, the mold is divided into two parts. the dimensions of each part (60*60*12.5 cm), see figure (1). two holes were made in the piece of cork at (15 cm) distance from each edge and the distance between holes is (30 cm) center to center, the dowels spacing which is recommended by (acpa) [5] specification, the hole diameter varies depending on the diameter of steel dowel bar used in specimen. in this research, the round and smooth steel dowels were used and placed in mid depth of concrete slab. the length of dowels varies with the diameter of dowels where the length of 300 mm for 12 and 16 mm dowels diameter and 350 mm for 20 mm dowel diameter, see table (1). before casting concrete the steel dowel bars were placed in position through the holes. as recommended by the aashto, astm, aci and acpa specifications, the expansion joints must be fixed in one side and free in the other, and has a cap provides a horizontal distance equal to the width of joints to allow movement of the pavement resulting from the change in temperature and moisture. steel dowel bars were greased on the free side so as not to restrict the horizontal movement of pavement. after preparation of the mold, the casting process begins, see figure (2). to simulate the subgrade soil in rigid pavement system, a subgrade soil container is made by the researcher. this container was made of (12 mm) thick steel plate with (130 * 70 * 20 cm) internal dimensions. to represent the subgrade soil, the wet soil was dried in the air to remove the water and get the dry soil. then the soil is cleaned, ground and sieved by a sieve (no.4). after that, the dry soil passing from sieve (no.4) with optimum moisture content were mixed by hand to get a homogeneous mixture. in the steel container, soil is placed in five layers, each layer with about (4 cm) thickness and each layer of soil is compacted by a steel rod, see figure (3). the jointed concrete pavement slabs are rested on compacted soil in a steel container and the specimens then setting on the hydraulically universal testing machine. using a steel plate of (60*8.5 cm) dimensions, the load was applied at (6 cm) distance from joint edge on the slab where dowel bar is fixed to concrete. the vertical deflections were measured using two dial gages of (0.01 mm) accuracy (one gage at each edge of the joint). both dial gages are placed at top surfaces of the slabs, see figure (4). uplifts of the far ends of concrete slabs were observed and recorded during the test. four specimens were tested on the subgrade soil and the load was applied incrementally until the failure of specimen. table 1, dowels for concrete parking lots, city streets and highways [16] total dowel length† mm dowel embedment* mm dowel diameter mm slab thickness mm pavement 300 350 350 350 400 125 150 150 150 180 15 20 25 25 30 125‡ 150‡ 175‡ 200 225 parking lots (aci 330r) 360 360 400 400 430 125 125 150 180 200 20 22 25 28 32 150‡ 165‡ 180‡ 190 225 city streets (pca 1992) jointed reinforced pavements with joint spacing greater than (6 m) 450§ 500§ 190 225 30 40 <250 ≤300 highways (acpaa 1991) zainab ahmed al-kaissi al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 6880 (2018) 70 * on each side of joint, 6 times dowel diameter for load transfer. † includes allowance for joint opening and minor errors in positioning — 2 times embedment length + 2 to 3 in. (50-75 mm). ‡ dowels may be impractical in thinner pavements. § computed from recommendations in acpaa (1991), which also states: most agencies specify 18-in.(450-mm-) long dowels for typical highway pavement. note: dowel spacing 12 in. (300 mm). fig. 1. the cork piece is used to represent the joint. fig. 2. casting process of specimen. fig. 3. preparation of compacted soil layers. fig. 4. test of the specimen on subgrade soil. 4. materials 4.1 cement in this study, iraqi portland cement (type v) of tasluja factory which is named commercially (al-gesr cement) was used, cement has been tested and the results were compliant with the iraqi standards iq.s 5/1984. 4.2 fine aggregate the natural river sand from al-sudoor region is used in concrete mix so as to achieve the midrange gradient specification. the fine aggregate gradation of the used sand which conforms to iraqi specification i.q.s 45/1984 and aashto t27-99. 4.3 coarse aggregate the crushed gravel from al-niba'ee region is used in concrete mix so as to achieve the midrange gradient specification. the grading of the used coarse aggregate conforms to aashto m43-09, no. 67. 4.4 steel dowel bars the used steel dowel bars were round and smooth. the steel dowel bars were supplied from local markets. in this study, three different diameters of steel dowel bar (12, 16 and 20 mm) were used as shown in figure (5). table (2) shows properties of the used steel dowel bars. steel zainab ahmed al-kaissi al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 6880 (2018) 71 dowel bars tests were conducted at the national center for construction laboratories and research (ncclr). fig. 5. steel dowel bars. table 2, properties of dowel bars 4.5 soil in this study, two types of soil were used as a subgrade foundation layer. first type of soil (type i) was taken from al-jaafer region of baghdad city and the second type (type ii) of soil taken from al-salameaat region of baghdad city. table (3) shows the soil properties for each type. table 3, properties for both types of soil. 5. concrete mixture proportions the normal strength concrete (nsc) was used in this study. based on several trials mixes with each mix, control specimens three cubes with dimensions 150*150*150 mm and three prisms with dimensions 100*100*500 mm were cast to determine compressive strength and modulus of rupture, respectively. table (4) shows mix proportions per cubic meter for normal type of concrete and table (5) shows details of the specimens. table 4, proportions of mix per cubic meter normal strength concrete material 400 cement (kg/m³) 600 sand (kg/m³) 1200 gravel (kg/m³) 0.5 w/c table 5, details of the specimens length of steel dowel bar (mm)* diameter of steel dowel bar (mm) type of subgrade soil specimen designation 300 12 a-6 n-12-i 300 16 a-6 n-16-i 300 16 a-7-5 n-16-ii 350 20 a-6 n-20-i *the length of the steel dowel bars used as recommended by the aci 330r 6. general behavior of the tested specimens generally, similar behavior was observed in all the tested specimens under loading. the load was applied from zero with (10 kn) increments. up to approximately (20% to 25 %) of ultimate load, the concrete slabs show no downward deflection on both edges of the joint, after that the concrete ultimate load (kn) elongation (%) ultimate strength (mpa) yield strength (mpa) diameter (mm) 99.55 8.7 886 822 12 153.84 11.5 756 709 16 250.04 9.8 796 766 20 type ii type i specification properties 19.9 20.15 aashto t90 96 plastic limit (%) 46.4 35.22 aashto t89 96 liquid limit (%) 26.5 15.07 aashto t90 96 plasticity index 16 13 aashto t99 95 optimum moisture content (%) 1.85 1.8 aashto t99 95 max. dry density (g/cm³) 5 7 aashto t193 93 cbr value at optimum moisture content (%) a-7-6 a-6 astm d3282 09 soil classification zainab ahmed al-kaissi al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 6880 (2018) 72 slabs start to move upward on both sides of the applied load due to dowel bar bending, this uplift is clearly observed at slabs far ends. this is because that the far ends of the slabs were unrestrained and free to move upward. with increasing loads, dowels continue to exert bearing stresses on to the underneath concrete and consequently uplift continues until failure of the loaded slab which characterized by flexural crack approximately under or adjacent to the applied load, see figure (6). fig. 6. the tested specimens at failure. 7. mechanical load transfer between dowel and concrete the load transfer mechanism between the dowel and the concrete is a complex phenomenon [6]. the dowel bar-concrete bearing stress can be calculated by the equation (1) depending on the assumption, that the embedded dowel bar behaves as beam on elastic foundation [7] . σb =ko y …(1) where: σb : bearing stress (mpa) ko : dowel support modulus (n/mm^2) y : deflection of dowel bar (mm) the pressure on the dowel bar which causes deflection in the concrete pavement of (1 mm) this is known as the modulus of the dowel support (ko). this means, the dowel bar modulus represents the properties of elastic in the dowel bar. the modulus of dowel support is affected by several factors which are diameter and shape of the dowel, yield strength of the dowel bars, concrete depth under the dowel, compressive strength of the concrete, elastic modulus of concrete and load ]8[. according to yoder [6]and huang ]9[ the modulus of dowel support ( ko) is assumed from 300000 to 1500000 pci (81.5 to 409 gn/m³) because the value of dowel support modulus is difficult to find them. when contact between the steel dowel and the surrounding concrete is good, high value of dowel support modulus is assumed, but the contact between the steel dowel and the surrounding concrete deteriorates with repeated wheel loads, the concrete with time and repeated load may be crushed and created the voids around the dowels and lead to dowel looseness (dl). in this study, the load is applied at distance x from joint face and distance c from end of dowel, see figure (7). fig. 7. the beam on elastic foundation so the deflection of the dowel bar can be calculated based on the theory of beam (dowel bar) on elastic foundation (concrete) [10] by equation below: y = �� ��� ��� �� �� � �� ���+ ���� ����� � ��� �� � � � �� � ����� � � � �� �� � � � �� ! …(2) where: y: deflection of dowel bar (mm) β: relative stiffness of the dowel bar (1/mm) e: elastic modulus of dowel bar (n/ mm�) i: moment of inertia of the dowel bar (mm#) zainab ahmed al-kaissi al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 6880 (2018) 73 p: the transfer load (n) $%: modulus of dowel support (n/mm�) x: distance along dowel measured from the point of the applied load (mm) c: distance from dowel end in the loaded slab to the point of load (mm) m:bending moment on dowel (n.mm) v:shearing force (n) the relative stiffness of the dowel bar can be calculated using equation (3) [11]: β = & � #�� ' … (3) according to friberg [7] k can replaced by $%d and re-write as: β = &�� ( #�� ' …(4) where: k: modulus of foundation (mpa/mm) $%: modulus of dowel support (n/mm�) d: diameter of dowel bar (mm) the length of dowel bar is assumed semi-infinite according to friberg [7] . but the length of dowel bar is finite, so the equation above can be used if the βl is more than 2 [12]. the bending moment on dowel (m) and shearing force (v) can be calculated by equations (5) and (6), respectively [12]: m = � � #� ���) �� �� � �� ��� …(5) v = � � � ���)�� �� …(6) figure (8) shows the distribution of bearing stress (calculated using equation (1)) along the dowel bar of the specimen n-16-i (all other specimens have similar distribution). as shown in figure 8 maximum bearing stress occurs under the applied load and decreases as the distance from the applied load increases until approximately the joint face where bearing stress, values become negligible. fig. 8. distribution of bearing stress along dowel bar for (n-16-i) specimen 8. failure mechanism of the tested specimens in general, all the specimens behaved elastically and did not show defects or cracks at low levels of load but when the load exceeds (20% to 25%) of the ultimate load the slabs started to uplift. then the loaded slab failed suddenly by a tension crack generated at tension (bottom) face of concrete slab and propagated fast to the compression face splitting the loaded slab into two parts. however this is no to typical failure of concrete pavements and it happens because the edges of the concrete slabs were unrestricted as mentioned earlier. the above described failure mechanism occurs when the induced tensile stress (*+) in the bottom face (under the load) exceeds the concrete ultimate tensile strength (*+,). to verify this assumption, the following approach is proposed: failure tensile stress (*+) has two components, namely: flexural tensile stress (*+-) and splitting tensile stress (*+�), flexural tensile stress is a result of the moments caused by the uplift bearing stresses (�.�/0123) minus the moments caused by concrete slabs weight (�4�135+), see figure (9). fig. 9. the flexural tensile stress. *+-can be calculated using flexural formula: *+6 78 � …(7) � 6 �.�/0123 � �4�135+ …(8) �.�/0123 6 9∗ ;<=� 9� ∗ ;<=� …(9) 96 > ?.) @ a …(10) 9� 6 > ?.bc�) @ a …(11) ;<=6 > ?.) @ . �a / > ?.) @ a …(12) ;<=� 6 > ?.bc�) @ . �a / > ?.bc�) @ a …(13) where: 9-, 9�: bearing uplift forces at two sides of the applied load. ;<=-: distance from 9to p. zainab ahmed al-kaissi al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 6880 (2018) 74 ;<=�: distance from 9� to p. all the above integrals are evaluated numerically using trapezoidal rule with strip width of 5 mm. splitting tensile stress (*+�) is a lateral tensile stress acts along the slab depth as a result of the compressive stress under and at the section of the applied load, see figure (10). fig. 10. the splitting tensile stress. *+�can be calculated by using equation (14) [13]: *+� 6 �� h(b …(14) where: p: applied load (n) d: depth of the slab (mm) l: width of the slab (mm) table (6) lists the calculated failure tensile stress (*+) as direct summing of *+-) and *+�) for comparison purpose with the ultimate tensile strength *+,) which is 3 4⁄ *0�[14]. table 6, the results of the mechanical properties for the experimental models . eq. (4.7) : eq. (4.14) ∴ *+ 6 *+� *+� ∷ *+, 6 n op # as shown in table (6) specimens n-12-i and n-16-i failed when *+ appreximatly reaches *+, (94% and 99% of *+,, respectively). specimen n20-i failed at *+ higher than *+, (*+ *+,⁄ =1.25) because the maximum size for dowel bar (diamater and length) increase the strength of specimen. can be explained the induced crack at failure of specimen n-20-i which is start inclining under the applied load at the bottom and deviated toward the end of the dowel at the top and did not penetrate the slab depth vertically as observed in the other specimens, see figure (6). specimen n16-ii failed at *+ lower than *+, (*+ *+,⁄ = 0.62) because that the weaker subgrade allows concrete slabs to move downward under load which may cause additional tensile stresses that are not considered in calculating *+, so it can be concluded that eq. (7) underestimates the actual flexural tensile stress at failure in specimen n-16ii. 9. effect of dowel bar diameter although increasing dowel bar diameter reduces bearing stresses between bar and concrete, diameter has a very little effect on failure loads with only 5% increase when dowel bar diameter increases from 12mm to 16 mm or 20 mm because the failure of the tested specimens was highly dependent on concrete strength as discussed in the previous section. however using 20 mm diameter of dowel bar n-20-i made the slab to fail with inclined tension crack unlike 12mm and 16mm diameters (n-12-i and n-16-i). in general, the load-deflection behavior of specimens with three different dowel diameter (12, 16 and 20 mm) are similar, as shown in figure (11). this comparable behavior assures no significant effect of dowel bar diameter on the load-deflection behavior of specimens tested in this experimental study. specimens qrs mpa qt mpa uv kn qwx ∙ mpa qwz ∶ mpa qw ∴ mpa qwv ∷ mpa qw qwv⁄ n-12-i 27 3.91 190 1.13 1.61 2.74 2.93 0.94 n-16-i 27 3.91 198 1.22 1.68 2.9 2.93 0.99 n-20-i 27 3.91 197 2 1.68 3.68 2.93 1.25 n-16-ii 27 3.91 132 0.68 1.12 1.8 2.93 0.62 zainab ahmed al-kaissi al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 6880 (2018) 75 fig. 11. effect of dowel bar diameter on loaddeflection (loaded slab). 10. effect of subgrade soil the results show that using type ii (cbr=5%) gives lower failure load than type i (cbr=7%) by 33%, this implies the importance of subgrade support resistance (strength) on concrete pavements performance. this result is also illustrated in figure (12) where type i specimen (n-16-i) shows stiffer load-deflection behavior than type ii specimen (n-16-ii). fig. 12. effect of subgrade type on load-deflection (loaded slab). 11. creation and analysis of the finite element models by the abaqus/cae to represent the specimens, 3-d geometry model of two layers (concrete slab and subgrade soil) of rigid pavement was used. the dimensions of a numerical models similar to the laboratory models dimensions which are (1210*600*125 mm) dimensions of concrete slab, (10 mm) width of joint and (200 mm) depth of subgrade soil. in a numerical models, striping load is applied at (6 cm) distance from edge joint (similar loading technique that are used in experimental models), see figure (13). the value of load of each model applied at ultimate load. table (7) shown properties of material. the elastic modulus of subgrade soil determined by cbr value for soil that measured from experimental test according to the equation below [17]: mr = 2555*(cbr)0.64 …(15) where: mr: resilient modulus of subgrade (psi). cbr: california bearing ratio. the elastic modulus of steel dowel bar was assumed and the elastic modulus of concrete measured from experimental test. the poisson’s ratio values for all materials are assumed according to huang [9]. three contact created between model parts, the first contact between subgrade soil and concrete slab where the friction coefficient very small value was assumed, the second contact between each dowel bars and surrounding concrete in fixed side of slab and third contact also between each dowel bars and concrete surrounding but in free side of slab where the coefficient of friction (0.35 and 0.05 respectively) were assumed according to alhumeidawi [15], see figure (14). as already reminded in experimental work, the subgrade soil was put in the steel container on five layers compacted for a depth of steel container is (200 mm). therefore, the soil has become a solid block. the boundary condition of the subgrade soil is fixed. the concrete slab remained without the boundary condition (similar to the experimental models), see figure (15). fig. 13. 3-d general geometry of the concrete pavement in abaqus. zainab ahmed al-kaissi al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 6880 (2018) 76 table 7, the material properties used in abaqus models. fig. 14. the contacts used in the models. fig. 15. the boundary condition of abuqus models. 12. abaqus program results from the figure (16), the load-deflection results behavior of loaded side (dl) and unloaded side (du) for experimental models and numerical models were have same behavior approximately. table (8) show the ultimate deflection for loaded side (dl) and unloaded side (du) where the difference between the numerical and experimental range from (4.65% to 18.5%). table (9) show the statistical analysis by t-test where the results have no significant difference between the experimental results and the numerical results for ultimate deflection at loaded side and unloaded side. table 8, the comparison between the results of the ultimate deflection of experimental and numerical models of loaded side (dl) and unloaded side (du) specimens deflection of abaqus models (mm) deflection of experimental models (mm) \]qq. ^_ ∗ (%) \]qq. ^v ∗∗ (%) da db da db n-12-i 0.63 0.17 0.68 0.19 7.35 10.52 n-16-i 0.64 0.18 0.7 0.22 8.57 18.18 n-16-ii 0.41 0.12 0.43 0.14 4.65 14.29 n-20-i 0.69 0.22 0.74 0.27 6.76 18.5 * diff. fg 6 fgh�fgi fgi **diff. fj 6 fjh �fji fji where: diff. fg: difference of deflection between abaqus and experimental models for loaded side. diff. fj: difference of deflection between abaqus and experimental models for unloaded side. dah : deflection of loaded side for abaqus models. dai : deflection of loaded side for experimental models. dbh: deflection of unloaded side for abaqus models. dbi: deflection of unloaded side for experimental models. properties of material poisson’s ratio (µµµµ) elastic modulus (e) kpa materials isotropic and linear elastic 0.45 61000 type i (a-6) subgrade soil 50000 type ii (a-7-6) isotropic and linear elastic 0.15 24422000 concrete isotropic and linear elastic 0.3 200000000 dowel bar zainab ahmed al-kaissi al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 6880 (2018) 77 table 9, the statistical analysis by t-test results of the ultimate deflection of experimental models and numerical models side t-test t at k 6 0.05 result loaded 0.4737 1.9432 insignificant unloaded 0.9511 1.9432 insignificant zainab ahmed al-kaissi al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 6880 (2018) 78 fig. 16. the behavior of load-deflection at loaded and unloaded sides for abaqus and experimental mode. 13. conclusions 1. the behavior of load-deflection is similar for specimens tested with different size of dowel bars diameter (12, 16 and 20 mm) with little effect of diameter of dowel bar on the tested specimens behavior slightly stiffer behavior is observed as the dowel diameter increases from 12 mm to 20 mm with only 5% increase in failure load. 2. the cbr value of subgrade soil that supported the concrete slab in jointed plain concrete pavement effect the failure load and loaddeflection behavior where the soil type ii (cbr=5%) have failure load less than soil type i by about 33%. 3. failure of the tested specimens was characterized by a flexural crack approximately under or adjacent to the applied load in the loaded concrete slab. 4. the numerical analysis by abaqus program shows numerical models were have same behavior of experimental models approximately and the statistical analysis by ttest shows the results have no significant difference between the experimental results and the numerical results for ultimate deflection at loaded side and unloaded side. notation aashto american association of state highway and transportation officials astm american concrete institute acpa american society for testing and materials i.q.s iraqi standards specifications 3-d fem three dimensional finite element method cbr california bearing ratio w/c water/cement ratio jpcp jointed plain concrete pavement jrcp jointed reinforced concrete pavement crcp continuously reinforced concrete pavement 14. references [1] westergaard, h. m., “stresses in concrete pavements computed by theoretical analysis.” public roads, vol. 7, pp. 25 – 33, 1926. [2] hogg, a. and hall, a., “equilibrium of a thin plate symmetrically loaded, resting on an elastic subgrade of infinite depth.” philosophical magazine, series 7, vol. 25, 1938. [3] pickett, g and ray, g. k., “influence charts for concrete pavements.” american society of civil engineers transactions, american society of civil engineers, vol. 116, pp 4973, 1951. [4] chelliah madasamy, lssam e. harik, david l. allen, l. john fleckenstein, “laboratory testing and analysis of joints for rigid pavements.” research report ktc-9922, 1999. [5] american concrete pavement association (acpa), “design and construction of joints for concrete highways.” acpa, skokie, il, 24 pp, 1991. [6] yoder, e. j., and m. w. witczak. “principles of pavement design” second edition, john wiley and sons, inc., new yoiic, 1975. [7] friberg, b.f., “design of dowels in transverse joints of concrete pavements”, transactions, american society of civil engineers. vol.105, no. 2081, 1940. [8] friberg, b. f., “design of dowels in transverse joints of concrete pavements.” transactions, american society of civil engineers, 105(2081), 140-161, 1938. [9] huang, y. h., “pavement analysis and design.” 2nd edition, prentice, hall, englewood cliffs, new jersey, 2004. [10] ansel c. ugural and saul k. fenster, “advanced and applied elasticity.” fourth edition, prentice hall, upper saddle river, new jersey, 2003. zainab ahmed al-kaissi al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 6880 (2018) 79 [11] timoshenko, s., and lessells, j. m., “applied elasticity.” westinghouse technical night school press, 1925. [12] porter, m., alberston, m., barnes, b., lorenz, e., and viswanath, k., "thermoset composite concrete reinforcement." report hr-325 submitted to project development division of the iowa department of transportation and iowa highway research board, 1992. [13] neville am, “properties of concrete.” 4th ed. prentice hall. illinois, 2005. [14] raphael, j., “tensile strength of concrete.” aci materials journal, no. 81-17, pp. 158165, 1984. [15] basim h. al-humeidawi,“ evaluation of the performance of gfrp dowels in jointed plain concrete pavement (jpcp) for road/airport under the combined effect of dowel misalignment and cyclic wheel load ” phd thesis, university of manchester, usk, 2013. [16] aci committee 224, “joints in concrete construction” aci 224.3r-95, american concrete institute, 1995. [17] witczak, m. w., houston, w. n., & zapata, c. e., “correlation of cbr values with soil index properties” development of the 2002 guide for the design of new and rehabilitated pavement structures, technical report. nchrp project,2001. )2018( 6880، صفحة 3د، العد14دجلة الخوارزمي الهندسية المجلمزينب احمد القيسي 80 دراسة تجريبية في مفاصل التمدد الموتّدة على سلوك التبليط الخرساني غير المسلح ***نبأ ستار كريم **محمد هاشم محمد *زينب أحمد القيسي المستنصريةالجامعة /قسم هندسة الطرق والنقل*** ،**،* googlemail.com77zainabalkaisi@ البريد االلكتروني: * m_sahlani@yahoo.com البريد االلكتروني: ** gmail.com1992eng.nabaa@البريد االلكتروني: *** الخالصة الهطول في مفاصل التمدد للتبليط الخرساني غير المسلح باستخدام قضبان الحديد كآلية لنقل الحمل عب6ر مفاص6ل التم6دد. -تتناول هذه الدراسة سلوك الحمل مل6م) وع6رض ٦٠٠بالطت6ين م6ن الخرس6انة المحلي6ة ك6ل بالط6ة بط6ول (تم أنشاء اربع موديالت لنظام التبليط الخرس6اني المحل6ي ك6ل مودي6ل يتك6ون م6ن عملياَ، ) ويس6تند dowel barsطة اثن6ين م6ن قض6بان الحدي6د االمل6س (امل6م ) بوس6 ١٠ملم) ويتم ربط البالطتين عبر مفصل تمدد عرض6ه ( ١٢٥ملم) وسمك ( ٦٠٠( dowelرياَ ت6م تن6اول متغي6رين ، المتغي6ر االول قط6ر قض6بان الحدي6د االمل6س (الموديل الخرساني على مكون بذلك موديل لنظام التبليط الجاسئ المحلي، مختب bars ) ولثالث قياسات (حسب تصنيف (بملم) والمتغير الثاني نوع التربة وهما نوعان ١٢، ١٦، ٢٠aashto) النوع االول :(a-6) والن6وع الث6اني (aالهطول حيث ل6وحظ -ملم له تأثير قليل على سلوك الحمل ٢٠ملم الى ١٢) من dowel barملس (وأظهرت النتائج التجريبية أن زيادة القطر الحديد اال ).7-5 ) يعتمد بش6كل رئ6يس عل6ى ق6وة مقاوم6ة flexural crack٪ فقط في حمل الفشل. ويمكن أن يعزى هذا إلى أن الفشل ناجم عن (٥من نتائج تحليل العينات زيادة ٪.٣٣حمل الفشل بنحو نقصان٪ يؤدي الى ٥٪ إلى ٧للتربة التحتية من cbrقيمة ننقصاالخرسانة. وأظهرت النتائج أيضا أن (microsoft word \307\315\343\317 \346\321\307\306\3172433) al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 14, no. 4, december, (2018) p.p. 2433 enhancement of hybrid solar air conditioning system using a new control strategy ahmed abed mohammed* raed ayad abduljabbar** *,**department of mechanical engineering / university of technology *email: 20187@uotechnology.edu.iq **email: me.21148@uotechnology.edu.iq (received 14 january 2018; accepted 25 april 2018) https://doi.org/10.22153/kej.2018.04.002 abstract enhancement of the performance for hybrid solar air conditioning system was presented in this paper. the refrigerant temperature leaving the condenser was controlled using three-way valve, this valve was installed after the compressor to regulate refrigerant flow rate towards the solar system. a control system using data logger, sensors and computer was proposed to set the opening valve ratio. the function of control program using labview software is to obtain a minimum refrigerant temperature from the condenser outlet to enhance the overall cop of the unit by increasing the degree of subcooled refrigerant. a variable load electrical heater with coiled pipe was used instead of the solar collector and the storage tank to simulate the solar radiation. experimental data was measured to study the performance of the system. the proposed system was compared with the conventional one. results show that the cop of the proposed system was higher than the cop of the conventional system by 10 %. in addition, the controlled system saved an electricity of 11.2 %. the optimum opening valve ratio fluctuated between 0.3 and 0.4 when the heater power was 500 w. keywords: hybrid system, evacuated tubes collector, three-way control valve. 1. introduction in summer, air conditioning represents a high cost in global building services in both commercial and residential buildings. the increased in thermal loads, living standards and residents comfort demands as well as building architectural characteristics caused an increasing in energy demand for air-conditioning. [1] heating, ventilation and air conditioning processes in buildings account about half of energy consumption, specifically air conditioning is expected to contribute significantly to the prospective growth to 2040. [2]. ha and vakiloroaya, 2012 [3] estimated the optimum refrigerant temperature entering the condenser in hybrid solar air conditioner system by proposing a by-pass line together with a three-way proportional control valve that installed after the compressor to control the refrigerant flow rate and enhance the performance of the system, results show that the average cop by using the optimal set-point values is higher than the commonly-used design by 6.7%. also, the lower refrigerant enthalpy entering the evaporator tends to decrease the compressor work and in turn avoids the unnecessary heat rejection in the condenser. vakiloroaya et al., 2013 [4] developed the hybrid solar air conditioning system by proposing a discharge bypass line together with an inline solenoid valve to increase the subcooling of the refrigerant at partial loads, the solenoid valve installed after the compressor to regulate the mass flow rate of the refrigerant. this development is promising between 25 and 43% of monthly electricity can be saved on average. vakiloroaya et al. 2013 [5] derived mathematical models for the components of hybrid solar air conditioner and then validated against experimental results. the models are derived based on the mass and energy ahmed abed mohammed al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 2433 (2018) 25 balance equations merging thermodynamics and heat transfer laws. simulation results were compared with the experimental data. it was shown that additional heat from solar collector to the refrigerant after the compressor allows it to be switched off longer to consequently reduce the overall electrical energy consumption. abid and jassim, 2015 [6] investigated an experimental study of the thermal performance of air conditioning system combined with a solar collector. the prototype consisted of three different process fluid loops: air-conditioning loop, collector loop, and cooling tower loop. the bypass installed after compressor to control the flow rate of the refrigerant and the load on the compressor. results showed that the cop increased from 2.493 to 2.725 when the solar radiation increased from 572 w/m2 to 725 w/m2, the average energy saving between 23% and 32%. kumar et al., 2016 [7] introduced their study about performance analysis of hybrid solar air conditioning system which consists of r410a vapour compression refrigeration cycle combined with evacuated tubes collector, the average coefficient of performance was about 2.71. hasanen et al., 2017 [8] investigated the mechanical and electrical performance of hybrid solar air conditioning system experimentally and analytically. the performance of hybrid and conventional system were compared. the results showed that the proposed system had not better performance and energy saving than the conventional one. the aim of this study is to investigate the enhancement of hybrid solar a/c system by utilizing a new strategy of control variable (outlet refrigerant temperature from the condenser) via three-way actuator valve. 2. experimental work the test rig consists of seven main components which are: rotary compressor, air-cooled finned tubes condenser, capillary tube, dx evaporator, electrical heater, three-way control valve. figures 1, 2 and 3 show a schematic block diagram, indoor and outdoor units of the test rig respectively. the cooling capacity of the compressor is 3.5 kw, and the working fluid is r22. finned tubes condenser with two rows and 20 tubes per row is used, the length of each row is 75 cm, and the outer tube diameter is 9.57 mm, the input power of condenser fan is 20 w. direct expansion evaporator with one row and 26 tubes per row is used, the length of the row is 65 cm and outer tube diameter is 7.6 mm an electrical heater is used instead of solar collector system to simulate the solar radiation, avoid weather fluctuations and cover a wide range of solar radiation. it is a galvanized steel box with dimensions of 65 × 25 × 12 cm, in one side of the box, an electrical coil of 500 w is supported, and in the other side, copper tube with 12.77 mm outer diameter and 7 m length is welded to form a heat exchanger. fig. 1. schematic diagram of the system. ahmed abed mohammed al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 2433 (2018) 26 fig. 2. indoor unit and control system. fig. 3. outdoor components. a twisted strip is inserted inside the pipe to increase the heat transfer rate between the refrigerant and pipe wall. the box is insulated from outside with glass wool and aluminum foil. a variac transformer is used to control the output power of the electrical heater manually. fig. 4 represents the details of the electrical heater. fig. 4. details of the electrical heater. a proportional three-way control valve model (lpa14-403b9cpc3-10-64), t port diverting type is used, with 1 ~5 v control signal actuator. it is installed after the compressor to regulate the flow rate of the refrigerant to the condenser and the electrical heater. the opening ratio of the threeway valve is controlled automatically (according to computer program associated with data acquisition) or manually. fig. 5 represents the three-way control valve. fig. 5. three-way control valve. 3. test room fig. 6 represents the test room which is built of sandwich panel room was constructed to represent the conditioning space. the dimensions of the room are 2×2×2 m. the evaporator was installed inside the room, while the compressor, condenser, capillary tube, three-way control valve and electrical heater were installed outside the room. the aim of constructing this room is to control the indoor conditions and reduce the number of variables, so that the effect of the remaining variables can be studied. two electrical heaters of 1000 w each was installed inside the room to simulate thermal load and prevent very low temperature that may be stop the system. ahmed abed mohammed al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 2433 (2018) 27 fig. 6. test room. 4. measuring instruments the parameters data are displayed and recorded automatically as in table 1. negative thermal coefficient thermistor (ntc) is used to measure the temperature. pressure transducer (danfoss) is used to measure refrigerant pressure. the gas flow meter is installed at the suction line to measure refrigerant flow rate. potential transformer (pt) and current transformer (ct) were used to measure the voltage and current of the system respectively. table 2 represents the measuring instruments and their specifications. table 1, measuring data. no. parameters notation 1 refrigerant temperature before and after each component. t1t9 2 refrigerant pressure before and after the compressor. p1, p2 3 refrigerant pressure before condenser and evaporator. p6, p8 4 refrigerant flow rate. v�� 5 inlet and outlet air temperature of the condenser and evaporator. t air evap. in., t air evap. out., t air cond. in., t air cond. out. 6 ambient and room temperature. t amb., t room 7 voltage and current of the system. v, i 8 electrical heater power p heater 5. control system the control system consists of the following: • data acquisition (national instrument ni), 32 ports, input power is 11~30 v dc, 50 w. • desktop computer • power supply • electronic cards and co-axial wire interface. • control program with labview software, the flow chart of the program was shown in fig. 7. the objectives of the control system are: 1. record and display the collected data from ntc, pressure transducers, flow meter, current transformer (ct) and potential transformer (pt) to via computer. 2. control the opening ratio (r) of three – way valve to regulate mass flow rate of the refrigerant that flows across the electrical heater (solar system) or direct to the condenser, by transmitting the signal to the three-way valve actuator according to the input signal transmit from the refrigerant temperature leaving the condenser (t7) via data acquisition. fig. 7. flow chart of the control program. in the automatic mode for the opening valve ratio (r), the control program regulates the ratio of mass flow equation of the refrigerant as a function of refrigerant temperature leaving the condenser (t7), where the opening ratio is set in position to achieve minimum refrigerant temperature leaving the condenser (subcooled) to increase the cop of the system. fig. 8 represents the national instrument data acquisition. ahmed abed mohammed al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 2433 (2018) 28 fig. 8. national instrument data acquisition. table 2, specifications of measuring instruments. 6. test procedures all tests were carried out in baghdad on october 2016. the system was charged with r22. for each test, the following procedures were followed: • turn on the system. • the computer and control program are turned on. • set the electrical heater power by the variac manually. • set the opening valve ratio, either manually or automatically. • set the number of reading and time intervals. • record the data (listed in table 1) in the computer by data logger. 7. parameters calculations the power consumption of the system can be calculated by the following equation: �����. = � × … (1) and the cooling capacity of the evaporator is expressed as: �� = ��� × (ℎ9 − ℎ8) … (2) while the coefficient of performance of the system is calculated by: ��� = �� ���� . … (3) 8. results and discussions many experimental tests were carried out on the system to study its thermal performance and compare it with the conventional system, just four tests are discussed in this paper as samples to other tests, and each test is studied within four characteristic parameters as following: 8.1 refrigerant temperature fig. 9a, 9b and 9c represent the refrigerant temperature at five positions along time, where the x-axis represents time in minutes and the y-axes represents inlet and outlet temperature of the compressor, outlet temperature of the heat exchanger, inlet and outlet temperature of the condenser and inlet temperature of the evaporator. results show that the transition period was taken 20 to 30 minutes until the system reaching the steady state. the refrigerant inlet temperature to the compressor (t1) was about 9.6 ˚c. the refrigerant temperature leaving the compressor (t2) was approximately constant with time by an average value of 93 ̊ c. the refrigerant temperature leaving the heat exchanger (t4) was directly proportional with the electrical heater power. the refrigerant inlet temperature to the condenser (t6) has the same behavior of t2, where in the case of automatic opening valve ratio (r), t6 was slightly lower than t2 as shown in fig. 9a, but in the case of r=0.5 and constant heater power, t6 was higher than t2 as shown in fig. 9b. while in the case of r=1 (manually) and variable heater power, t6 became higher than t2 when there was a sufficient heater power as shown in fig. 9c. the refrigerant temperature leaving the condenser (t7) and the refrigerant inlet temperature to the evaporator (t8) sensor type quantity specification ntc 22 operating range: -40 ~ 125 ˚c pressure transducer 4 operating range: 0 ~ 50 bar power supply: 24 v dc error: 1 % thread: male diameter: 9.53 mm output signal: 0 to 10 v. gas flow meter 1 operating range: 1.5 ~ 5 m3/hr model: cx-lwgq15amc4 error: 2.5 % dn: 15 thread: male power supply: 24 v dc analog output signal: 4 ~ 20 ma dc pulse screen display. ahmed abed mohammed al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 2433 (2018) 29 were approximately constant with time because it depends on t6 and ambient temperature, and their values do not have a big change with time. the average values of t7 and t8 were 41.3 ˚c and 6.1 ˚c respectively. 8.2 air temperature fig. 10a, 10b and 10c represent air temperature with time, where the x-axis represents time recorded and the y-axis represents the inlet and outlet air temperature of the condenser and evaporator, room and ambient temperature. the air temperature inlet the condenser has approximately the same value of the ambient temperature and it can be identical. the average air temperature difference between inlet and outlet the condenser was about 8.3 ˚c. the air temperature inlet the evaporator has the same behavior of the room temperature and it can be identical. it is clear that there is some fluctuation in the room temperature, and this is because of fluctuation in the thermal load inside the room. the average air temperature difference between inlet and outlet the evaporator was about 14.4 ˚c. 8.3 refrigerant pressure and flow rate the representation of the refrigerant pressure (p1, p2, p6, and p8) and volumetric flow rate with time were shown in fig. 11a, 11b and 11c. the refrigerant pressure follows the ambient temperature, it increased with time as shown in fig. 11a, while it approximately constant with time as shown in fig. 11b and 11c. the refrigerant pressure leaving the compressor (p2) was slightly higher than the refrigerant pressure inlet the condenser (p6) in the controlled and uncontrolled hybrid solar air conditioning system. the average value of the volumetric flow rate was slightly decreased with time as shown in fig. 11a, it ranged between 3.12 and 3.58 m3/hr, while it seemed constant with time by average value of 3.29 m3/hr as shown in fig. 11b and 11c. 8.4 power consumption, cooling capacity, electrical heater power, opening valve ratio and coefficient of performance the representation of power consumption (pcons.), evaporator cooling capacity (qe), electrical heater power (pheater), opening valve ratio (r) and coefficient of performance (cop) are depicted in fig. 12a, 12b and 12c. the power consumption is slightly increased with time as the thermal load increased, its average values are 977, 1116 and 1082 w. thus, the controlled system consumes less electrical power than another. qe is fluctuated with time because of the fluctuation in the thermal load inside the room, this lead to oscillate the cop of the system. qe is about 2985 w. the average value of the cop is 3 as shown in fig 12a. while it equals to 2.7 as shown in fig. 12b and 12c. it noted that cop of the controlled system is higher than cop of the uncontrolled one. in the case of controlled system, the refrigerant temperature leaving the condenser (t7) ranged from 36.6 to 43.4 ˚c when the heater power ranged from 0 to 500 w as shown in fig. 9a and 12a. while in the case of uncontrolled system, the refrigerant temperature leaving the condenser (t7) ranged from 40 to 43.8 ˚c when the heater power ranged from 0 to 250 w as shown in fig. 9c and 12c. that is mean, the controller can achieve lowest t7 during increase the solar radiation. the controller plays an important role in enhancement the performance of hybrid solar air conditioning system, where it achieved minimum possible refrigerant temperature leaving the condenser (t7) with maximum possible solar radiation. the lowest t7 means higher degree of subcooled and hence higher refrigeration effect. also, higher solar radiation lead to lower power consumption of the system. the opening valve ratio (r) increased by increasing the heater power (solar radiation) and fluctuated between 0.3 and 0.4 when the heater power is 500 w as shown in fig. 12a. so, this ratio represents the optimum ratio which achieves maximum value of cop at certain conditions. fig. 9a. refrigerant temperature with time for test 1 ahmed abed mohammed al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 2433 (2018) 30 fig. 9b. refrigerant temperature with time for test2. fig. 9c. refrigerant temperature with time for test3. fig. 10a. air temperature with time for test 1. fig. 10b. air temperature with time for test 2. fig. 10c. air temperature with time for test 3. fig. 11a. refrigerant pressure and volumetric flow rate with time for test 1. ahmed abed mohammed al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 2433 (2018) 31 fig. 11b. refrigerant pressure and volumetric flow rate with time for test 2. fig. 11c. refrigerant pressure and volumetric flow rate with time for test 3. fig. 12a. power consumption, cooling capacity, electrical heater power, opening valve ratio and coefficient of performance with time for test 1. fig. 12b. power consumption, cooling capacity and coefficient of performance with time for test 2. fig. 12c. power consumption, cooling capacity, electrical heater power and coefficient of performance with time for test 3. 9. conclusions 1. ability of utilizing three-way valve system in the improving the performance of hybrid solar air conditioning system. 2. this type of controller gives a wide scope to prepare alternative programmable software to regulate system performance by controlling other variables (pressure, enthalpy, etc.) to improve system efficiency. 3. the cop of the controlled hybrid solar air conditioning system is higher than the cop of the uncontrolled one by 10 %. 4. the controlled system saved an electrical power of 11.2 %. ahmed abed mohammed al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 2433 (2018) 32 5. the optimum opening valve ratio which achieves maximum value of cop at certain conditions is ranged between 0.3 and 0.4. 6. possibility of modeling the system using the electrical heater with variable capacity instead of the solar collector and the storage tank. nomenclature cop coefficient of performance. h8 refrigerant enthalpy inlet the evaporator. kj/ kg h9 refrigerant enthalpy outlet the evaporator. kj/ kg i current passes through the system. a m�� refrigerant mass flow rate. kg/s p1, p2 refrigerant pressure inlet and outlet of the compressor respectively. ba r p6 refrigerant pressure inlet to condenser. ba r p8 refrigerant pressure inlet to evaporator. ba r pcons power consumption by the system w qe cooling capacity of the evaporator. w r ratio of the opening valve to the storage tank to the opening valve to condenser directly. t1, t2 refrigerant temperature inlet and outlet of the compressor respectively. ˚c t3, t4 refrigerant temperature inlet and outlet of the storage tank respectively. ˚c t5 refrigerant temperature in the bypass line. ˚c t6, t7 refrigerant temperature inlet and outlet of the condenser respectively. ˚c t8, t9 refrigerant temperature inlet and outlet of the evaporator respectively. ˚c tair evap. in air temperature inlet to the evaporator. ˚c tair evap. out air temperature outlet from the evaporator. ˚c tair cond. in air temperature inlet to the condenser. ˚c tair cond. out air temperature outlet from the condenser. ˚c tamb ambient dry bulb temperature. ˚c troom room temperature. ˚c v voltage passes through the system. v v�� volumetric flow rate of refrigerant in the suction line. m3/hr 10. references [1] h.m. henning, solar assisted air conditioning of buildings – an overview, applied thermal engineering 27 (2006) 1734–1749. [2] m.t. evans, n. kapur, j. summers, h. thompson, d. oldham, an experimental and theoretical investigation of the extent of bypass air within data centres employing aisle containment, and its impact on power consumption, applied energy 186 (2016) 457-469. [3] q.p. ha, v. vakiloroaya, a novel solarassisted air-conditioner system for energy savings with performance enhancement, procardia engineering 49 (2012) 116-123. [4] v. vakiloroaya, r. ismail, q.p. ha, development of a new energy-efficient hybrid solar-assisted air conditioning system, international symposium on automation and robotics in construction and mining 30 (2013) 1424-1435. [5] v. vakiloroaya, q.p. ha, m. skibniewski, modeling and experimental validation of a solar-assisted direct expansion air conditioning system, energy and buildings 66 (2013) 524-536 [6] m.a. abid, n.a. jassim, experimental evaluation of thermal performance of solar assisted air conditioning system under iraq climate, journal of energy technologies and policy 5 (2015) 1-13. [7] s. kumar, d. buddhi, h.k. singh, performance analysis of solar hybrid airconditioning system with different operating conditions, imperial journal of interdisciplinary research 2 (2016) 19511956. [8] h.m. hussain, l.j. habeeb, o.j. abbas, investigation on solar hybrid cooling system with high latent cooling load, advances in environmental biology 11 (2017) 24-36. )2018( 24-33، صفحة 4د، العد14دجلة الخوارزمي الهندسية المجلم احمد عبد محمد 33 الشمسي الهجين باستخدام ستراتيجية سيطرة جديدةتحسين االداء لنظام التبريد رائد اياد عبد الجبار** حمد عبد محمد*أ ** قسم الهندسة الميكانيكية / الجامعة التكنولوجية،* uotechnology.edu.iq@20187*البريد االلكتروني: .uotechnology.edu.iq21148me@البريد االلكتروني: ** الخالصة درجة في هذا البحث تم دراسة تحسين االداء لنظام التبريد الشمسي الهجين ، حيث تم نصب صمام تحكم ثالثي بعد الضاغط مباشرة لغرض التحكم في م في نسبة تنظيم معدل تدفقه ، تم استخدام نظام سيطرة مع قارئ بيانات ومتحسسات وجهاز حاسوب للتحك عن طريقحرارة مائع التبريد الخارج من المكثف للحصول على اقل درجة حرارة للمائع الخارج من المكثف وذلك لتحسين معامل االداء الكلي للمنظومة من labviewفتحة الصمام ، تم استخدام برنامج اكاة االشعاع الشمسي. حخزان لمخالل زيادة درجة التبريد المفرط للمائع. تم استخدام سخان كهربائي متغير السعة مع انبوب ملف بدال من المجمع الشمسي وال ن معامل االداء للنظام المقترح اعلى أتم قياس عدد كبير من البيانات لغرض دراسة اداء النظام ، تم مقارنة النظام المقترح مع النظام التقليدي وقد بينت النتائج عندما كانت سعة قدرة السخان ٠٫٤و ٠٫٣ت نسبة فتحة الصمام ما بين % . وقد تراوح ١١٫٢، ويرشد طاقة كهربائية بنسبة %١٠من النظام التقليدي بنسبة واط. ٥٠٠حوالي احمد عبد الصاحب al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 8, no.3, pp 5362 (2012) sub–nyquist frequency efficient audio compression ahmed a. hashim department of computer/ college of science for women/ university of baghdad email:dreng.ahmed@yahoo.com (received 17 april 2011; accepted 20 march 2012) abstract this paper presents the application of a framework of fast and efficient compressive sampling based on the concept of random sampling of sparse audio signal. it provides four important features. (i) it is universal with a variety of sparse signals. (ii) the number of measurements required for exact reconstruction is nearly optimal and much less then the sampling frequency and below the nyquist frequency. (iii) it has very low complexity and fast computation. (iv) it is developed on the provable mathematical model from which we are able to quantify trade-offs among streaming capability, computation/memory requirement and quality of reconstruction of the audio signal. compressed sensing cs is an attractive compression scheme due to its universality and lack of complexity on the sensor side. in this paper a study of applying compressed sensing on audio signals was presented. the performance of different bases and its reconstruction are investigated, as well as exploring its performance. simulations results are present to show the efficient reconstruction of sparse audio signal. the results shows that compressed sensing can dramatically reduce the number of samples below the nyquist rate keeping with a good psnr. keywords: sub-nyquist sampling, compressive sampling, compressed sensing, nonlinear reconstruction, random matrices. 1. introduction the 20th century has seen the development of a huge variety of sensors/detectors acquiring measurement in a faithful representation of the physical world (e.g. radio receivers, optical sensors, seismic detector ...). since the purpose of these systems was to directly acquire a meaningful ''signal", a very fine sampling of this latter had to be performed. this was the context surrounding the famous shannon-nyquist condition stating that every continuous (a priori) band-limited signal can be recovered from its discretization if its sampling rate is at least two times greater than its cutoff frequency. recent theory named compressed sensing (or compressive sampling) [1, 2] states that this lower bound on the sampling rate can be highly reduced, as soon as, first, the sampling is generalized to any linear measurement of the signal, and second, specific a priori hypotheses on the signal are realized. more precisely, the sensing pace is reduced to a rate that equals a few multiple of the intrinsic signal dimension rather than the dimension of the embedding space. technically, this simple statement is a real revolution both in the physical design of sensors and in the theory of reliable signal sampling. it means that a "given signal does not have to be acquired in its initial space as previously, but it can really be observed through a "distorting glass" (providing it is linear) with fewer measurements". the history of compressed sensing has started in 2006 by the seminal works of d. donoho, e. cande's, t. tao and j. romberg [3, 4], even if some of its founding concepts, e.g. sparse recovery by convex optimization, were known from several decades. cs has actually emerged and grown from the rich multidisciplinary hotbed of information and sampling theory, inverse problems solving, statistics and measure concentration, graph theory, and highdimensional (polytope) geometry. in this paper i present a study of the performance of cs for a variety of audio signals and illustration the differences in performance mailto:dreng.ahmed@yahoo.com ahmed a. hashim al-khwarizmi engineering journal, vol. 8, no.3, pp 5362 (2012) 54 depending on the basis and the reconstruction algorithm used. 2. compressed sensing the nyquist-shannon sampling theorem states that to restore a signal exactly and uniquely, you need to have sampled with at least twice its frequency. of course, this theorem is still valid; if you skip one byte in a signal or image of white noise, you cannot restore the original. but most interesting signals and images are not white noise. when represented in terms of appropriate basis functions, such as trig functions or wavelets, many signals have relatively few non-zero coefficients. in compressed (or compressive) sensing terminology, they are sparse [5]. before starting with the mathematics related with cs let us first explain the idea with the following simple example: let us think of two numbers whose average is 3. what are the numbers? after complaining that there is no enough information, you might answer 2 and 4. if you do, you have unconsciously imposed a kind of regularization that requires the result to be two distinct integers; the problem is a 1–by–2 system of linear equations with matrix a= [1/2 1/2] and right–hand side b=3 we want to find a 2–vector y that solves ay=b. the minimum norm least squares solution is computed by the pseudo inverse, y =[3 3] but different solution is possible:x =[6 0]. both solutions are valid, but human puzzle– solvers rarely mention them. notice that the second solution is sparse; one of its components is zero. the signal or image restoration problem is a larger instance of the same task; we are given thousands of weighted averages of millions of signal or pixel values. our job is to re-generate the original signal or image. 2.1. problem statement of compressible signals consider a real-valued, finite-length, onedimensional, discrete-time signal x, which can be viewed as an n × 1 column vector in with elements x[n], n = 1, 2, . . . , n. any signal in can be represented in terms of a basis of n × 1 vectors . using the n × n basis matrix = [ψ1|ψ2| . . . |ψn] with the vectors {ψi} as columns, a signal x can be expressed as x = or x = ...(1) where s is the n × 1 column vector of weighting coefficients si = = ψi t x. clearly, x and s are equivalent representations of the signal, with x in the time or space domain and s in the domain. the signal x is k-sparse if it is a linear combination of only k basis vectors; that is, only k of the si coefficients in (1) are nonzero and (n − k) are zero. the case of interest is when k n. the signal x is compressible if the representation (1) has just a few large coefficients and many small coefficients. 2.2. transform coding and its inefficiencies the fact that compressible signals are well approximated by k-sparse representations forms the foundation of transform coding [3, 6]. in data acquisition systems (for example, digital cameras) transform coding plays a central role: the full nsample signal x is acquired; the complete set of transform coefficients {si} is computed via s = tx; the k largest coefficients are located and the (n − k) smallest coefficients are discarded; and the k values and locations of the largest coefficients are encoded. unfortunately, this sample–then–compress framework suffers from three inherent inefficiencies. first, the initial number of samples n may be large even if the desired k is small. second, the set of all n transform coefficients {si} must be computed even though all but k of them will be discarded. third, the locations of the large coefficients must be encoded, thus introducing an overhead. 2.3. the compressive sensing problem compressive sensing address these inefficiencies by directly acquiring a compressed signal representation without going through the intermediate stage of acquiring n samples [1, 7, 8]. consider a general linear measurement process that computes m < n inner products between x and a collection of vectors as in yj = . arrange the measurements yj in an m × 1 vector y and the measurement vectors t as rows in an m × n matrix . then, by substituting from (1), y can be written as …(2) ahmed a. hashim al-khwarizmi engineering journal, vol. 8, no.3, pp 5362 (2012) 55 k-sparse (a) (b) where is an m × n matrix. the measurement process is not adaptive, meaning that is fixed and does not depend on the signal x. the problem consists of designing a) a stable measurement matrix such that the salient information in any k-sparse or compressible signal is not damaged by the dimensionality reduction from to and b) a reconstruction algorithm to recover x from only m ≈ k measurements y (or about as many measurements as the number of coefficients recorded by a traditional transform coder). 2.4. designing a stable measurement matrix the measurement matrix must allow the reconstruction of the length-n signal x from m < n measurements (the vector y). since m < n, this problem appears ill-conditioned. if, however, x is k-sparse and the k locations of the nonzero coefficients in s are known, then the problem can be solved provided m ≥ k. a necessary and sufficient condition for this simplified problem to be well conditioned is that, for any vector v sharing the same k nonzero entries as s and for some > 0 …(3) that is, the matrix must preserve the lengths of these particular k-sparse vectors. of course, in general the locations of the k nonzero entries in s are not known. however, a sufficient condition for a stable solution for both k-sparse and compressible signals is that satisfies (3) for an arbitrary 3k-sparse vector v. this condition is referred to as the restricted isometry property (rip) [4]. a related condition, referred to as incoherence, requires that the rows { } of cannot sparsely represent the columns {ψi} of ψ (and vice versa). direct construction of a measurement matrix such as has the rip that requires verifying (3) for each of the possible combinations of k nonzero entries in the vector v of length n. however, both the rip and incoherence can be achieved with high probability simply by selecting as a random matrix. for instance, let the matrix elements be independent and identically distributed (iid) random variables from a gaussian probability density function with mean zero and variance 1/n [1, 2, 4]. then the measurements y are merely m different randomly weighted linear combinations of the elements of x, as illustrated in fig. 1(a). fig. 1. (a) compressive sensing measurement process with a random gaussian measurement matrix and discrete cosine transform (dct) matrix. the vector of coefficients s is sparse with k = 4. (b) measurement process with there are four columns that correspond to nonzero si coefficients; the measurement vector y is a linear combination of these columns [9]. the gaussiam measurement matrix has two interesting and useful properties: athe matrix is incoherent with the basis = i of delta spikes with high probability. more specifically, an m × n iid gaussian matrix = i = can be shown to have the rip with high probability if m ≥ c k log (n/k), with c a small constant [1, 2, 4]. therefore, k-sparse and compressible signals of length n can be recovered from only m ≥ ck log(n/k) random gaussian measurements. bthe matrix is universal in the sense that will be iid gaussian and thus have rip with high probability regardless of the choice of orthonormal basis . ahmed a. hashim al-khwarizmi engineering journal, vol. 8, no.3, pp 5362 (2012) 56 2.5. designing a signal reconstruction algorithm the signal reconstruction algorithm must take the m measurements in the vector y, the random measurement matrix (or the random seed that generated it), and the basis and reconstruct the length–n signal x or, equivalently, its sparse coefficient vector s. for k-sparse signals, since m < n in (2) there are infinitely many that satisfy = y. this is because if s = y then (s + r) = y for any vector r in the null space n( ) of . therefore, the signal reconstruction algorithm aims to find the signal’s sparse coefficient vector in the (n − m)-dimensional translated null space . aminimum l2 norm reconstruction: define the lp norm of the vector s as . the classical approach to inverse problems of this type is to find the vector in the translated null space with the smallest l2 norm (energy) by solving = argmin such that = y …(4) this optimization has the convenient closedform solution = t( )-1 y. unfortunately, l2 minimization will almost never find a k-sparse solution, returning instead a non sparse with many nonzero elements. bminimum l0 norm reconstruction: since the l2 norm measures signal energy and not signal sparsity, consider the l0 norm that counts the number of non-zero entries in s. (hence a k-sparse vector has l0 norm equal to k). the modified optimization = argmin such that = y …(5) can recover a k-sparse signal exactly with high probability using only m = k + 1 iid gaussian measurements [5]. unfortunately, solving (5) is both numerically unstable and np complete, requiring an exhaustive enumeration of all possible locations of the nonzero entries in s. cminimum l1 norm reconstruction: surprisingly, optimization based on the l1 norm = argmin such that = y …(6) can exactly recover k-sparse signals and closely approximate compressible signals with high probability using only m ≥ ck log(n/k) iid gaussian measurements [1], [2]. this is a convex optimization problem that conveniently reduces to a linear program known as basis pursuit whose computational complexity is about o(n3). 2.6. the reason behind the convergence of l1 rather than l2 the geometry of the compressive sensing problem in helps visualize why l2 reconstruction fails to find the sparse solution that can be identified by l1 reconstruction. the set of all k-sparse vectors s in is a highly nonlinear space consisting of all k-dimensional hyper planes that are aligned with the coordinate axes as shown in fig. 2(a). the translated null space is oriented at a random angle due to the randomness in the matrix as shown in fig. 2(b). (in practice n, m, k 3, so any intuition based on three dimensions may be misleading) the l2 minimizer from (4) is the point on closest to the origin. this point can be found by blowing up a hyper sphere (the l2 ball) until it contacts . due to the random orientation of , the closest point will live away from the coordinate axes with high probability and hence will be neither sparse nor close to the correct answer s. in contrast, the l1 ball in fig. 2(c) has points aligned with the coordinate axes. therefore, when the l1 ball is blown up, it will first contact the translated null space at a point near the coordinate axes, which is precisely where the sparse vector s is located. while the focus here has been on discretetime signals x. ahmed a. hashim al-khwarizmi engineering journal, vol. 8, no.3, pp 5362 (2012) 57 idct(f2) 0 0.01 0.02 0.03 0.04 0.05 -2 -1 0 1 2 f1 = signal1 0 0.01 0.02 0.03 0.04 0.05 -2.5 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 2.5 f2 = signal1 0 500 1000 1500 2000 2500 3000 3500 4000 -10 0 10 20 30 idct(f1) 1000 1500 2000 2500 3000 3500 -30 -20 -10 0 10 20 30 40 50 idct(f2) fig. 2. (a) subspaces with two sparse vectors in r3 lie close to the coordinate axes. (b) visualization of the l2 minimization (5) that finds the non-sparse point-of-contact s between the 2 ball (hyper-sphere, in red) and the translated measurement matrix null space (in green). (c) visualization of the l1 minimization solution that finds the sparse point-of-contact s with high probability thanks to the pointiness of the l1 ball. 3. simulation results three types of signals are taken, based on complexity in time domain and in terms of sparsity, see fig. 3. these signals are sampled and then reconstructed from few randomly selected samples, fig. 4 shows the sampling of the first signal of cutoff frequency 1.633khz with sampling frequency of 14khz and then taking randomly 10% of these samples to reconstruct the signal. the figure shows that reconstruction with l1 – norm is accurate with psnr of 20.5db while reconstructing using l2 – norm was very pad and gave meaningless results. fig. 5 shows the original signal3 (with highest sparsity) with cutoff frequency of 1633 and the reconstructed one with different random samples (m)/total samples (n) rations. ahmed a. hashim al-khwarizmi engineering journal, vol. 8, no.3, pp 5362 (2012) 58 0 0.002 0.004 0.006 0.008 0.01 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 f3 = signal3 2600 2800 3000 3200 3400 3600 3800 -20 0 20 40 60 80 idct(f3) .005 .010 .015 .020 .025 .030 -1 0 1 0 100 200 300 400 -10 -5 0 5 10 0 100 200 300 400 -10 -5 0 5 10 .005 .010 .015 .020 .025 .030 -1 0 1 0 100 200 300 400 -10 -5 0 5 10 .005 .010 .015 .020 .025 .030 -1 0 1 wave= signal =f1, points = random sample = 10% of fs idct (f1) dct (x) y = l2 solution, a*y = b idct (y) x = l1 solution, a*x = b fig. 3. three time domain signals with their idct. fig. 4. a) signal and its random samples b) its sparse representation in idct c) reconstruction using l1 in the sparse domain d) reconstructed signal using l1 e) reconstruction using l2 in the sparse domain f) reconstructed signal. ahmed a. hashim al-khwarizmi engineering journal, vol. 8, no.3, pp 5362 (2012) 59 (a) original and reconstructed signal with m/n =0.8, psnr = 38.6. (b) original and reconstructed signal with m/n = 0.5, psnr = 32. 0 0.005 0.01 0.015 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 0 0.005 0.01 0.015 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 0 0.005 0.01 0.015 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 0 0.005 0.01 0.015 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 0 0.005 0.01 0.015 -2 -1 0 1 2 0 0.005 0.01 0.015 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 0 0.005 0.01 0.015 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 0 0.005 0.01 0.015 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 (c) original and reconstructed signal with m/n = 0.1, psnr = 21. (d) original and reconstructed signal with m/n =0.05, psnr = 19.6. ahmed a. hashim al-khwarizmi engineering journal, vol. 8, no.3, pp 5362 (2012) 60 0 0.005 0.01 0.015 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 0 0.005 0.01 0.015 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 fig. 5. original and reconstructed signal with different m/n ratios and the psnr for them, the cutoff frequency of the signal is 1.63khz and fs = 14khz 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 5 10 15 20 25 30 35 40 45 50 55 signal3 signal2 signal1 fig. 6. the psnr versus m/n ratio for the three under testing signals. e) original and reconstructed signal with m/n =0.02, psnr = 12.5 from fig.5, one can see the good reconstruction even when the m/n ratio is small; the psnr for each case reflects the goodness of reconstruction. fig. 6 shows the psnr versus m/n ratio for the three under testing signals, from the figure one can see that as the sparsity of the signal increases; the reconstruction with lower m/n ratio is possible. it is important here to say that since the reconstruction process is based on random sampling; the psnr gained may vary based on (by chance) hitting the target (the random samples takes the largest values of the signal in the sparse domain) it is convenient here to say that compressive sensing also applies to sparse or compressible analog signals x(t) as well as digital ones 4. conclusions signal acquisition based on compressive sensing can be more efficient than traditional sampling for sparse or compressible signals. in compressive sensing, the familiar least squares optimization is inadequate for signal reconstruction, and other types of convex optimization must be invoked. the cs is nonlinear sampling, so that it is an arbitrary and unknown set of size k, exact recovered from cklog(n/k) (almost) arbitrarily placed samples, and nonlinear reconstruction by convex programming. it is important to mention here that the mp3 and jpeg files used by today’s audio systems and digital cameras are already compressed in such a way that exact reconstruction of the original signals and images is impossible. ahmed a. hashim al-khwarizmi engineering journal, vol. 8, no.3, pp 5362 (2012) 61 5. references [1] justin romberg and michael wakin ''compressed sensing: a tutorial'', ieee statistical signal processing workshop, madison, wisconsin, 2007. [2] albert cohen, et al. ''compressed sensing and best k-term approximation'' , naval resarch contracts onr-n00014-03-1-0051, 2006 [3] yin zhang '' on theory of compressive sensing via l1-minimization: simple derivations and extensions'', caam technical report tr08-11, 2008 [4] emmanuel cand`es and justin romberg '' l1magic: recovery of sparse signals via convex programming'', 2005 [5] alyson k. fletcher ''necessary and sufficient conditions for sparsity pattern recovery'', ieee, revision of arxiv:0804.1839v1 [cs.it], 2009 [6] cleves corner ''the world's simplest impossible problem'', the mathworks newsletter, vol.4, no. 2, 1990 [7] p. wojtaszczyk ''stability of l1 minimisation in compressed sensing'',2009 [8] yin zhang ''when is missing data recoverable?'', caam technical report tr06-15, 2006 [9] kaichun k. chang , …etal, “sub-nyquist audio fingerprinting for music recognition”, 2010 )2012( 5362، صفحة 3، العدد 8مجلة الخوارزمي الھندسیة المجلد ھاشم أحمد عبد الصاحب 62 نایكویستقل من أبإستعمال تردد ءوكف صوت ضغط ھاشم الصاحبأحمد عبد جامعة بغداد /تللبنا كلیة العلوم/ الحاسوبقسم علوم dreng.ahmed@yahoo.com اللكترونيا البرید: الخالصة ھذا النوع من الضغط . المتناثرعینة عشوائیة من إشارة الصوت ال معلى أساس مفھوسریع وفعال ألخذ العینات تعرض ھذه الورقة تطبیق إطار ضغط تشكیل االشاره الصوتیة بالضبط القیاسات المطلوبة إلعادة عدد) ب(متناثرة الشارات اإلمجموعة متنوعة من ل ةي طریقھ شاملھ) أ. (یوفر أربع سمات ھامة خالل من) ث( اتالحسابب وسرعھمنخفضة التعقید للغایة )ت(تردد نایكویست أقل منخذ العینات والمستعمل ألأقل بكثیر من التردد ھو األمثل تقریبا و اء البن، ونوعیة إعادة ةالمطلوب ذاكرةالمبادالت نسبھ الى الحجم تدفق قدرة حساببین ةمقارننحن قادرون على تحدید ضعھا في نموذج ریاضي یمكن اثباتھ و تقدیم دراسة في ھذه الورقة تم. جانب االستشعارلعالمیتھ وعدم وجود تعقید في نظرًا إسلوب ضغط جذابھو csمضغوط الاالستشعار . شارات الصوتیةلإل ى اشارات ذات اسس بتطبیقھا عل ةالطریقھ وقدرتھا على اعادة تشكیل االشار أداء تم التحقیق من. على اإلشارات الصوتیة المضغوط لتطبیق االستشعار مضغوط الالنتائج تظھر أن االستشعار . ةمتناثرالاإلشارات الصوتیة تشكیلنتائج المحاكاة موجودة إلظھار كفاءة إعادة . ھامختلفھ ، وكذلك استكشاف أداء الى ضوضاء ةعلى نسبة أعلى اشار ةمع المحافظأقل من معدل نایكویست الصوتیة ةالمطلوبھ ألعادة تشكیل االشارحد بشكل كبیر من عدد العینات یمكن أن ی psnr ةجید. mailto:dreng.ahmed@yahoo.com <4d6963726f736f667420576f7264202d20cde3edcf20e6e4d5d1ca20e6c7cdd3c7e420e6cac8edede439302d3938> al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 14, no. 1, march, (2018) p.p. 90-98 construction and evaluation of a uniaxial mechanical actuated vibration shaker hameed d. lafta* nasrat k. murad** ihasan j.khamas*** tebin f. abdalla**** *,**college of technical engineering/ sulaimani polytechnic university ***,**** sulaimani technical institute/ sulaimani polytechnic university *email: hameed.lafta@spu.edu.iq **email: nasrat.kareem@yahoo.com ***email: ahsanjbr@yahoo.com ****email: tebeenfaraidwn2000@yahoo.com (received 22 february 2017; accepted 11 october 2017) https://doi.org/10.22153/kej.2018.10.006 abstract in the present paper a low cost mechanical vibration shaker of rotating unbalanced type with uniaxial shaking table was designed and constructed in an attempt to provide opportunities for experimental testing and application of vibration in experimental modal analysis, stress relief of weldments, effect of vibration on heat transfer and seismic testing of civil engineering structures. also, it provides unexpressive solution to enhance the knowledge and technical skills of students in mechanical vibration laboratory. the shaker consists of a five main parts shaker frame, shaker table, flexible support, drive motor, and eccentricity mechanism. the experimental results show that the amplitude of the shaker is increased with increasing the frequency ratio and the maximum value was attained near the resonance condition. also, the magnitude of amplitude is increased with increasing the eccentric mass and eccentricity values. a reasonable agreement with theoretical results shows that the shaker can be used with reliable results in vibration testing purposes. also, in this paper, the frequency ranges of the shaker were determined for constant displacement and for constant acceleration tests to satisfy all the frequency limitation requirements of the mechanical shaker. keywords: rotating unbalance, uniaxial shaker, vibration shaker. 1. introduction academic exposure to vibration experimentation and instrumentation usually arises in relation to learning, training, and research. generally, an experimental vibration system consists of four main subsystems, and the excitation system is one of these four integral parts [1]. the excitation system serves to generate specific signal in a controlled manner through a device which it is called vibration exciter. thus, vibration exciter or shaker is equipment can be used to produce vibration motion to test object under different excitation conditions of forces and displacements through a given range of frequencies. nitinkumar anekar, et.al [2] state that certain machines and structures that develop or subjected to excessive vibrations during their life may be required to make a diagnostic vibration analysis to prevent an impending failure of some components, and such components can be tested using vibration exciters. hameed d. lafta al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 9098 (2018) 91 in designing of vibration shaker, three specifications are of primary importance: the force rating, the power rating, and the stroke rating (maximum displacement). force and power ratings are particularly useful in moderate to high frequency excitations and the stroke rating is the determining factor for low frequency excitations. clarence w. de silva [1] presented a procedure to determine conservative estimates for these parameters in selecting of a specified vibration exciter. robert l. norton [3] provides basic information of designing of small components included in exciter design similar to nuts, bolts, springs, structure of frame, selection of motor and other design considerations. signal acquisition and modification is an important subsystem in vibration experimentation system. the instrumentation systems and techniques for vibration measurement are key factors to ensure the quality of the measured data and therefore there are many practical implications that must be taken into account [4]. s. s. rao [5] provides information on vibration analysis, signal acquisition and vibration instruments. also, the effects of viscous and coulomb damping are discussed and calculation of equivalent viscous damping is presented. during high level vibration test on a high mass specimen, the test engineer is often facing difficulty to pass properly the specified vibration level due to coupling between the specimen and the shaker, thus sébastien hoffait and et.al. [6] they are presented a methodology to define a virtual shaker testing simulator. the first step involves the dynamic identification of a 80kn shaker performed thanks to measurements (modal analysis and sine sweep).the second step is the definition of the physic represented in the simulator two test cases are described to demonstrate the possibilities offered by the simulator. amongst different types of vibration exciters a mechanical vibration exciter is significantly less expensive than the other types and no need for high skill operation maintenance. thus, the present work is devoted to construct a mechanical vibration exciter in an attempt to provide opportunities in experimental testing and application of vibration in different research area, such as, experimental modal analysis for structures, stress relief for weldments by vibration, enhancement of heat transfer, in heating and cooling system, by application of vibration, and can be used for prototype testing of civil engineering structures (seismic testing). also, this shaker provides unexpressive solution for motivating students to validate theories related to the forced vibration in mechanical vibration laboratory. accordingly, a low cost mechanical vibration shaker of rotating unbalanced type with uniaxial shaking table was designed, manufactured and tested to be reliable and applicable for vibration simulation and testing purposes at different frequencies and amplitudes. 2. vibration exciters vibration experimentation may require an external exciter to generate the necessary vibration. this is the case in controlled experiments such as product testing, determination of the dynamic characteristics of machines and structures, simulation, and testing of materials properties where a specified level of vibration is applied to the test object and the resulting response is monitored. a variety of vibration exciters are available, with different capabilities and principles of operation. three basic types of vibration exciters (shakers) are widely used: hydraulic shakers, mechanical shakers, and electromagnetic shakers. the operation-capability ranges of typical exciters in these three categories are summarized in table 1. vibration shaker may be able to reproduce motion in only one horizontal direction (uniaxial), or in one horizontal and the vertical direction (biaxial), or in both horizontal directions and the vertical direction (triaxial). triaxial shakers are the most realistic but also more expensive. many tests and much research are consequently done on uniaxial or biaxial vibration shakers [7]. hameed d. lafta al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 9098 (2018) 92 table 1, typical operation-capability ranges for various vibration shaker types [1]. 3. mechanical vibration exciters in mechanical exciters, the force drives the shaking table is generated by inertia forces (accelerating masses), and the generated force is sinusoidal in nature and it’s limited by the strength of the shaking frame [1]. a variety of mechanical vibration exciters are available with different operation mechanisms, such as: scotch yoke, rotating unbalance mass and eccentric cam. in the present work, a mechanical exciter of unbalance rotating type is considered. the general arrangement of a counter rotating unbalance mass exciter is shown in fig.1 [1]. it can be seen that, the generated excitation force is sinusoidal with frequency of ω and amplitude of (2me�ω2) which is directly proportional to the square of magnitude of the excitation frequency (ω2). consequently, the frequency and amplitude of the excitation force can be varied over a range of interest by incorporating a variable speed motor. also, the amplitude can be varied by varying the magnitudes of both the eccentricity (e) and the unbalance mass (m). however, different mechanisms are used to produce the excitation force. fig. 1. general arrangement of rotating unbalance vibration shaker. in rotating unbalance vibration shaker, as shown in fig.1, the generated force is directly transferred as a reaction force to the shaking table (test), on which the test object is mounted, via the carriage. the carriage with the whole system is mounted on a flexible support. in dynamic testing of large structures, the carriage can be mounted directly on the structure. the main advantages of mechanical vibration exciters are significantly less expensive than other types of vibration exciters. their sinusoidal generated forces are virtually undistorted when sinusoidal shaking force test is required and their limitation is determined by the strength of their carriage frame, [1]. the main limitations or disadvantages of these exciters they are not capable of producing complex, random vibration, and constant force testing. also, their frequency range of operation and maximum velocity and acceleration are low to intermediate compared with other types of shakers. m m ω ω e e test object with fixtures test object with fixtures mechanism of generating rotating unbalance carriag flexible support shaking table typical operation capability excitation waveform maximum force maximum acceleration maximum velocity maximum displacement (stroke) frequency shaker type average flexibility (simple to complex and random high 100,000 ibf 450,000 n intermediate 20 g intermediate 50 in.s-1 125 cms-1 high 20 in. 50 cm intermediate 0.1-500hz hydraulic (electrohydraulic sinusoidal only intermediate 1000 ibf 4500 n intermediate 20 g intermediate 50 in.s-1 125 cms-1 low 1 in. 2.5 cm low 2-50hz inertial (counter-rotating mass high accuracy and flexibility (simple to complex and random) low to intermediate 450 ibf 2000 n high 100 g intermediate 50 in.s-1 125 cms-1 low 1 in. 2.5 cm high 2-10,000hz electromagnetic (electrodynamic) hameed d. lafta al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 9098 (2018) 93 4. mathematical background unbalance in rotating machine is a common source of vibration exciter. a simple model of rotating unbalance machine is shown in fig. 2 [5]. the total mass of the machine is m, and there are two eccentric masses, 2 m with an eccentricity (e), rotating in opposite directions with a constant angular velocity (ω). fig. 2. rotating unbalanced masses. from geometrical of the system, it can be seen that the horizontal components of forces are equal and opposite in direction, thus, they are one cancel each other. however, the vertical components of excitation forces are added together and act along the axis of symmetry a-a. let, x, be the displacement of the nonrotating mass (m-m) from the static equilibrium position. then, the displacement of rotating unbalances mass (m), is ( tex ωsin+ ), and the equation of motion of the system can be obtained using newton’s second law as follows: )sin()( 2 2 tex dt d mxmmxckx ω++−=−− &&& …(1) where c and k are the damping and spring constants of the system. re-arranging the equation above, then: tmekxxcxm ωω sin 2=++ &&& …(2) the particular solution to the preceding equation is a steady-state oscillation of the system with the same frequency ω as that of the excitation. thus the particular solution can be assumed: )sin( φω −= txx …(3) the amplitude and phase shift, can be obtained by substituting eq. (3) into eq. (2). thus, the amplitude and phase shift are given by: ( ) ( )222 2 ωω ω cmk me x +− = …(4) 2 tan ω ω φ mk c − = …(5) these equations can be further expressed in terms of the following quantities: n n c nc n r k c c c mc m k ω ω ω ω ς ω ς ω ω = = = = = 2 2 …(6) substituting ωn, ζ, and r in eqs. (4) and (5), then the nondimensional forms are given by: ( ) ( )222 2 21 rr r me mx ς+− = …(7) 2 1 2 tan r r − = ς φ …(8) the variation of the amplitude ratio ( me mx ) and the phase angle (φ) versus frequency ratio r for different values of (ζ) are shown in fig. 3 [5]. (a) hameed d. lafta al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 9098 (2018) 94 (b) fig. 3. variation of amplitude ratio and phase angle versus frequency ratio for different values of ζζζζ. [5] from graphs shown in fig.3, is observed that, all curves of the amplitude ratio is beginning at zero and attain its maximum values near resonance condition. also, at high frequency ratio, the amplitude ratio equal to unity irrespective of the damping values, in other words, the effect of the damping on the system amplitude can be neglected. 5. design considerations and construction in vibration experimentation and dynamic system tests, the reproduction of accurate dynamic signals with a vibration shaker it may be considered a very important aspect to achieve reliable and meaningful results. however, the distortion of the desired signal depends on the dynamic characteristics of the subsystems of the shaking table-payload system and their interaction [8]. thus, the design and construction of a vibration shaker was carried out with keep in mind that all the design considerations should be satisfied in order to meet the dynamic specifications of mechanical vibration shakers shown in table 2. on the basis of the aforementioned considerations, a uniaxial mechanical actuated vibration shaker is designed and constructed. the mechanical actuating mechanism is of a rotating unbalance type. the shaker consists of a five main parts: shaker frame, shaker table and carriage assembly, flexible support, drive motor, and eccentricity mechanism, an overview of the shaker is shown in fig.4. fig. 4. overview of the mechanical vibration shaker. the shaker frame is constructed by using right angle section of size of 4 inches made of structural steel with overall dimensions of (40*80*80) cm of the upper part and (80*80*80) cm of the lower part with tapered front. the shaker table, which it is used to support the test object, is made of steel plate with overall dimensions of (40*20*0.4) cm. the shaker table is rigidly attached to the moving part which it is called carriage. the carriage is made of square section structural steel of size 2 inches , and it is allowed to move vertically via two guide rails fixed to the shaker frame and four rollers fixed to the carriage frame. the carriage is suspended vertically via two springs are attached to the upper part of the shaker frame. the springs are tested to satisfy all the requirements of static and dynamic loading conditions [3]. the schematic diagram of the shaker with the measuring instruments is shown in fig. (5). fig. 5. schematic diagram of the shaker with the measuring instruments c a b shaker table shaker frame carriage spring drive motor unbalance mass & eccentric mechanism hameed d. lafta al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 9098 (2018) 95 the shaking force of this mechanical vibration shaker is generated by using an eccentric mass fixed to long slotted bar by t-bolt (see fig. (6.a)). the slotted bar is made of steel hollow square section of 5 cm and the slots is produced by using cn milling machine to satisfy all the requirements of static and dynamic balancing. the slot bar can be provided an eccentricity range between (3-15) cm. also, the t-bolt supports up to 0.5 kg of eccentric mass. in this manner, the magnitude of the eccentricity and eccentric mass can be varied easily to produce different excitation forces. the slotted bar and the eccentric mass are driven by variable speed motor. the drive motor speed is controlled via digital controller (see fig. (6.b)), thus different excitation frequency can be achieved. the maximum motor excitation frequency is 100 hz. a vibration meter of (tv110) type is used to measure shaker table amplitude, velocity and acceleration. the meter is provided with an accelerometer that can be fixed to the shaker table by magnetic base (see fig. (6.c)). the measured signal is processed by using response spectrum analysis and the output is displayed in digital form three frequency ranges are available for this vibration meter and it is capable of measuring frequency up to 10 khz. fig. 6. unbalance mass & eccentric mechanism, motor drive controller, and vibration meter with accelerometer details 6. calculation of the system damping constant. the designed and constructed vibration shaker, in the present work is of a reaction shaker type, and different types of damping may be induced due to sliding friction and structural damping. thus, the calculation of the system damping in terms of an equivalent viscous damping is achieved to determine the value of the damping ratio of the vibration shaker. different methods are available in literature to find the system equivalent damping constant [1, 5], the most widely used method is called q factor or quality factor. the method assumes that the quantity q is equal to the amplitude ratio at the resonance frequency, then the q factor is equal to [5] : 12 1 2 1 rr q − ≈= ς …(8) where r1 and r2 are the frequencies ratio, and referred to as half power points, when the amplitude ratio falls to ( 2 q ), as shown in fig. 7. fig. 7. harmonic response curve showing half power points. 7. results and discussions the specifications, of the vibration shaker constructed in the present work, are shown in table (2), below. table 2, specifications of the vibration shaker. shaker table mass (m) (including all moving parts) 39.5 kg eccentric mass (m) (0.131-0.437) kg eccentricity (e) (3-12) cm motor speed (with digital controller 01.0± hz) (0-60)hz the natural frequency of the shaker table is calculated to be (4.26) hz. the vibration shaker is well tested to finding out the actual (a) slots t-bolted eccentric mass eccentricity scale (b) (c) hameed d. lafta al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 9098 (2018) 96 performance of the constructed system through several experimental tests. using the data given above, the amplitude of the shaker for different range of frequencies are determined experimentally and compared with the theoretical one. figs.(8), (9), and (10) show the variation of the shaker amplitude with the frequency ratio nω ω for different values of the eccentric mass (m). the reasonable agreement between the theoretical and experimental results, indicate that the shaker can be used with acceptable results in vibration testing purposes. fig. 8. shows the variation of the amplitude versus frequency ratio for m=0.182 kg, and e=0.12 m. fig .9. shows the varaition of the amplitude versus frequency ratio for m=0.284 kg, and e=0.12 m. fig. 10. shows the varaition of the amplitude versus frequency ratio for m=0.386 kg, and e=0.12 m. figs. (10), (11), and (12), show the variation of the shaker amplitude with the frequency ratio nω ω for different magnitudes of the eccentricity (e). it is clear that the maximum amplitude produced by the shaker is increased with increasing the eccentricity magnitude, thus the shaker permits to produce different excitation forces in accordance with user requirements. fig. 11. shows the varaition of the amplitude versus frequency ratio for m=0.386 kg, and e=0.1 m. fig.12. shows the varaition of the amplitude versus frequency ratio for m=0.386 kg,and e=0.08 m. hameed d. lafta al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 9098 (2018) 97 8. dynamic characteristics and testing limitations the dynamic characteristics of a vibration shaker, the pay load capacity and testing range, limitations are determined. the capabilityoperation ranges of a vibration shaker are specified by the test object size, displacement, velocity, acceleration and frequency ranges produced by the shaker, and their determination are very important to explain the allowable testing area of the shaker. the present shaker is designed to withstand a testing object of maximum mass of 49 kg, and maximum allowable displacement of 0.5 cm. the frequency range of the shaker is (3-30) hz. the maximum velocity of the shaker is 13 cm/sec, and the maximum acceleration does not exceed 2.5g. 9. conclusions a mechanical vibration shaker of rotating unbalance type with uniaxial shaking table was designed constructed and tested. the shaker is well tested to determine their dynamic characteristics and limitations. the overall damping factor of the shaker was calculated by using the q factor method. also, the effect of rotating unbalance were examined and it is found that the magnitudes of eccentric mass and eccentricity values are controlling the amplitude and force capacity of the vibration shaker. the constructed shaker is designed to withstand a test object of 49 kg and allowable maximum displacement of 0.5 cm. the vibration testing can be achieved over a range of frequencies of (3-30) hz, at designing limitation of maximum acceleration of (2.5g) and maximum velocity of (13 cm/s). the good agreement between the experimental results and the theoretical results, show that the vibration testing can be carried out with reasonable results. notation c damping constant cc critical damping constant e eccentricity k spring constant m mass of the shaking table m unbalance mass r frequency ratio x amplitude due to forced oscillation x displacement shaker greek letters ωn system natural frequency ζ damping ratio ω forced frequency φ phase of the displacement with respect to exciting force. acknowledgment the authors would like to thank mr. aso abdulah the engineer at theory of machines and vibration laboratory for his support, and mr saman hama sa’aeed the technician at workshops, for setting up the equipments at technical engineering college at spu. 10. references [1] clarence w. de silva, vibration fundamentals and practice. crc press llc.2000 [2] nitinkumar anekar, v.v. ruiwale, shrikant nimbalkar, and pramod rao “ design and testing of unbalance mass mechanical vibration exciter,” ijret, vol. 3, issues 8, pp. 107-112, 2014. [3] robert l. norton, “machine design: an integrated approach,” 5th edition, pearson 2013. [4] everaldo de barros, carlos d'andrade souto, leandro ribeiro de camargo, mauro hugo mathias “application of a computer sound card for measurement of mechanical vibrations,” revista brasileira de ensino de fsica, v. 37, n. 4, 4313 (december 2015). [5] s.s. rao, mechanical vibrations. 5th edition, pearson education, inc. 2011. [6] sébastien hoffait, frédéric marin, daniel simon, bart peeters, and jean-claude golinval, “measured-based shaker model to virtually simulate vibration sine test”. case studies in mechanical systems and signal processing, published by elsevier 3 may 2016. [7] paul ibanez “an introduction to shake tables for seismic testing of equipment and glossary of vibration terminology”. anco engineers, october 2008. [8] t. baran, a.k. tanrikulu, c. dundar, and a.h. tanrikulu “ construction and performance test of a lawcost shake table”. experimental techniques july/august 2011. )2018( 90-98، صفحة 1د، العد14دجلة الخوارزمي الهندسية المجلم حميد دويج لفتة 98 بناء وتقييم هزاز ميكانيكي احادي االتجاه احسان جبار خماس*** **نصرت كريم مراد *حميد دويج لفتة ****تيبين فريدون عبدالله جامعة السليمانية التقنية كلية التقنية الهندسية/ ،*** جامعة السليمانية التقنية معهد السليمانية التقني/ ،******* hameed.lafta@spu.edu.iq*البريد االلكتروني: nasrat.kareem@yahoo.com :البريد االلكتروني** ahsanjbr@yahoo.com :البريد االلكتروني*** tebeenfaraidwn2000@yahoo.com :البريد االلكتروني**** الخالصة طئة يوفر فرصة جيدة للباحثين الواكلفة ال ومنصة احادية االتجاه ذات الكتلة الدورانية االهتزازية يم جهاز هزاز ميكانيكي ذبناء وتقويفي هذا البحث تم ودراسة تاثير في مجال اجراء االختبارات الديناميكية وتطبيقات االهتزازات في مجال التحليلالت التجريبية الشكلية وازالة االجهادات لوصالت اللحام رارة واختبارات الهزات االرضية لهياكل المنشآت المدنية. وكذلك يساهم هذا الجهاز في توفير فرصة لتعزيز الجانب المعرفي االهتزازات في انتقال الح آلية و والماطور الكهربائي و المساند المرنة ومنصة الهزاز و الهيكل. يتالف هذا الجهاز من خمسة اجزاء ة للطلبة في مختبرات االهتزازاتوالخبرة الفني ها لهذا الجهاز ان ازاحة منصة الهزاز تزداد بزيادة التردد النسبي ؤالتحكم في قيمة ومحور الكتلة الالاتزانية. تبين النتائج واالختبارات العملية التي تم اجرا بزيدتهما. يشير الى الذروة بالقرب من التردد النسبي عند الرنين. وكذلك تبين التائج ان االزاحة تتاثر بقيمة كتلة ومحور الكتلة الالاتزانية وتزداد لوتص قيمة التحميل القصوى للجهاز عند وكذلك تم تحديد التوافق بين النتائج العملية والنظرية الى ان الجهاز مالئم الجراء االختبرات االهتزازية بنتائج مقبولة. اقصى ازاحة وسرعة وتعجيل لغرض استيفاء المتطلبات الديناميكية لمحددات الهزازات الميكانيكية. al-khwarizmi engineering!!! journal al-khwarizmi engineering journal, vol. 7, no. 2, pp 14 21 (2011) the effect of the solution heat treatment on the mechanical properties of aluminum-copper alloy (2024-t3) using rolling process hani aziz ameen * asma hassan ismail ** khairia salman hassan *** * department of dies and tools engineering/ technical college/ baghdad e-mail: haniazizameen@yahoo.com ** department of mechanical engineering/ college of engineering/ university of baghdad e-mail: asma.sawaf@yahoo.com *** department of mechanic/ institute of technology/ baghdad e-mail: almaden20002000@yahoo.com (received 2 august 2010; accepted 19 april 2011) abstract the effect of solution heat treatment on the mechanical properties of aluminum-copper alloy. (2024-t3) by the rolling process is investigated. the solution heat treatment was implemented by heating the sheets to 480 c° and quenching them by water; then forming by rolling for many passes. and then natural aging is done for one month. mechanical properties (tensile strength and hardness) are evaluated and the results are compared with the metal without treatment during the rolling process. ansys analysis is used to show the stresses distribution in the sheet during the rolling process. it has been seen that good mechanical properties are evident in the alloy without heat treatment due to the strain hardening and also the mechanical properties are improved after heat treatment and rolling process but with lower forces and stresses when compared with the untreated. keywords: forming process, rolling, heat treatment, ansys. 1. introduction the ability to use the rolling processin different industries purposes depends on whether the metal is ferrous or non ferrous. this is because of the different mechanical properties, e.g., strength, ability of plastic forming and physical properties like thermal, electrical and magnetic conductivities. from the important things for choosing the suitable metal for production is having confined chemical construction and good ability for plastic forming in order to take the desired form without changing the chemical instruction of metal experimentally. due to the ability of plastic forming of metal by applying confined force related with the volume and shape of the product, the procedures are various depending on the way of applying the force; these procedures are: rolling, dragging, extrusion, bending and shearing. wang (2009), studied the alloy (al–10.8zn–2.8mg–1.9cu) synthesized by the spray atomization and deposition technique. microstructure and mechanical properties of the spray-deposited alloy processed through hot rolling and heat treatment were investigated by means of scanning electron microscopy (sem), transmission electron microscopy (tem), x-ray diffraction and tensile test. the results indicate that the microstructure of the spray-deposited alloy is mainly composed of the al matrix and the mg(zncu)2 compounds. the fragmentation of the mg(zncu)2 phases in the alloy has been regarded as one of the main feature during hot rolling. after solution treating, the microstructure is found to be composed of the al matrix and a spot of al7cu2fe, al9feni compounds. the spraydeposited al–zn–mg–cu alloy in the t6 temper displays superior strength due to the presence of two types of coherent gp zones (spherical gpi zones and thin platelet gpii zones). shahani et al, (2009), parametrically studied hot rolling process by the finite element method of aa5083 this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ hani aziz ameen al-khwarizmi engineering journal, vol. 7, no. 2, pp 14 21 (2011) 15 aluminum alloy. chandramohan et al (2009) made a review for of rolling process with ohsas and texture formation. this study investigates the effect of solution heat treatment on the mechanical properties using rolling process is. 2. calculating the force and energy required for rolling process the required force for rolling in simple rolling mechanism with two rollers could be calculated as shown in fig. (1) by equation (nagpal,1998) : fr = l w σ qp …(1) fig.1. dimensions of rolling process. from fig.(1), it is seen that the output speed is greater than the input speed for the constant speed of rollers and there is one point of contact angle (α) in case of the sheet and rollers moves in the same speed. due to this process the friction force affects at the neutral point therefore it is important for rolling which cause to reduce the energy from the rollers caused forming. if the friction coefficient of roller approaches to zero, the roller will slide on sheet, the means no forming will be done, so that the lubrication must be controlled during the rolling process to prevent skidding ( johnson and needham,1982) . the force during the rolling process could be calculated related to the contact line measured from equation (2). l= √r(ho – hi) …(2) in the case of (h/l<1), the roller diameter is bigger when compared with the sheet thickness and the plastic deformation will be plane strain case and homogeneously and the rolling pressure can be determined from pr = σ tm qp …(3) hence, the force is equal to fr =l w σ tm qp …(4) in spite of that the length increases along the rolling but the width will be constant if (w/h>10) is for the most rolling processes. from equation (4) it is seen that the decrease in contact length (l) by decreasing the radius of roller made the required force decrease . in case of (h/l>1) which means that the sheet thickness is bigger when compared with roller radius therefore the non homogeneous forming occurrs, because of sticking which is undesired, but it happens in rolling process for big blocks, and pressure could be obtained in this case by(johson and miller,1973); pr = σ tm qi …(5) the non homogeneous deformation could cause cracking defect in the condition of; 18.1*)1(  i oo h h r h …(6) the torque of roller obtained from t=fr l …(7) the roller power could be determined by; power = ω t …(8) where ω is the angular velocity determined from; ω = v / r …(9) 3. experimental part 3.1. alloy selection aluminum alloy (2024-t3) had been selected treatable because an employment in many engineering applications such as air transmission structures. to check up the chemical instruction of metal alloy, chemical analysis had been done by spectrometer and the results explained in table(1). this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ hani aziz ameen al-khwarizmi engineering journal, vol. 7, no. 2, pp 14 21 (2011) 16 1.5 mm 20 m m 100m m table 1, chemical instruction for aluminum alloy (2024-t3). element al ti cr zn si fe mn mg cu real value 92.6 0 0.05 0.1 0.4 0.3 0.6 1.5 4.4 standard value 0-0.15 0-0.1 0-0.25 0-0.5 0-0.5 0.30-0.9 1.2-1.8 3.8-4.9 however the mechanical properties illustrated in table(2), where the available alloy sheet was formed as a plate having 10mm thickness to be suitable for deferent conditions research like making rolling processes experiments in deferent rates. table 2, mechanical properties of aluminum alloy (2024t3). ρ (kg/m3) elongation el.% u mpa y mpa (proof stress 0.2%) 280010%483414 3.2. preparing sheets for rolling the dimension of the rolling sheet is shown in fig.(2). fig.2. specimen dimensions. table 3, classification of used sheets. specimen symbol case athe basic material brolled without heat treatment b1rolled to 1.4mm b2rolled to 1.275mm b3rolled to 1.2mm b4rolled to 1.1mm csolution treatment before rolling 3.3. classification of sheets after cutting the sheets they had been classified into groups shown in table (3). 4. heat treatment solution solution heat treatment had been done for sheets (type c) where the sheets are heated to 480 c° temperature then cooled quickly (quenching ) by water. 5. rolling process rolling process had been done for sheets (types b & c) from table (3) by rolling machine has two rollers of 50mm diameter. 6. manufacturing test specimens to evaluate mechanical properties, the sheets are manufactured according to table (3), as follows: 6.1. tensile test specimens four specimens are formed according to standard (din 50125) specification, there dimensions are shown in figure (3). fig.3. tensile specimen (din 50125). 7. tests 7.1. the rolling process 1measuring grains size for specimen group before and after rolling by using optical microscope having a camera, the results are explained in table(4) and fig.(4). this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ hani aziz ameen al-khwarizmi engineering journal, vol. 7, no. 2, pp 14 21 (2011) 17 table 4, the granule size before and after rolling process. specimen symbol a b1 b2 b3 b4 granule size (μ) 3.68 8.61 15.02 18.32 7.45 fig.4. microstructure for the sheets (a), (b1), (b2), (b3) and (b4). a b1 b2 b3 b4 this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ hani aziz ameen al-khwarizmi engineering journal, vol. 7, no. 2, pp 14 21 (2011) 18 2measuring rigidity for groups of table (3) treated and untreated. by brinill hardness test method using a ball with 2.5mm diameter and 50kg load, the results explained in tables(5) and (6). table 5, mechanical properties of alloy after rolling without heat treatment rolling force n yield stress mpa maximum tensile stress mpa brinill rigidity number of passing thickness mm specimen symbol 781293.65111061.557a 1521277.6390.5100.541.4b1 2130304.342611061.275b2 2840339474.7123101.2b3 3481365.8512133121.1b4 table 6, mechanical properties of heat treatment alloy after rolling rolling force n yield stress mpa maximum tensile stress mpa brinill rigidity number of passing thickness mm specimen symbol 608253355911.557a 60829140810541.557c1 6082663739641.557c2 60831744411541.557c3 60830638210341.557c4 608295401.75104.7541.557c average where the heat treatment alloys c1, c2, c3 and c4 are corresponding to b1, b2, b3 and b4 respectively with constant thickness, number of passing and rolling force. it can be seen the properties is differed with each case, and it properties is much better than the untreated one. 8. ansys model generation the ultimate purpose of a finite element analysis is to re-create mathematically the behavior of an actual engineering system. in other words, the analysis must be an accurate mathematical model of a physical prototype. in the broadest sense, the model comprises all the nodes, elements, material properties, real constants, boundary conditions and the other features that used to represent the physical system. in ansys terminology, the term model generation usually takes on the narrower meaning of generating the nodes and elements that represent the special volume and connectivity of the actual system. thus, model generation in this study will mean the process of defining the geometric configuration of the model's nodes and elements. the program offers the following approaches to model generation: creating a solid model and using direct generation. the method used in this research to generate a model is solid model. in solid modeling someone can be described the boundaries of the model, establish controls over the size and desired shape elements automatically, i.e. drawing the two dimensional specimen model and meshing using meshtool. solid modeling is usually more powerful and versatile than other modeling, and is commonly the preferred method for generation models. the two dimension model of specimen is done by plotting and meshing two dimension axisymmetric plane with elements, the sheet element is visco106 and the contact condition is used via elements contac171 for deformable body and target169 for rigid body. ansys software is used to analyze many case in linear and non-linear (saeed moveni, 1999). in this study ansys software is used to analyze and this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ hani aziz ameen al-khwarizmi engineering journal, vol. 7, no. 2, pp 14 21 (2011) 19 study the forming process i.e rolling process (kawałek, 2007) and stresses distribution in the sheet with different conditions is evaluated. the model generated for nonlinear materials and non linear geometry in addition to contact case between the sheet and roller, also it is non linear process (ansys, 1999). four types of elements are used as shown in fig. (5) fig.5. rolling process model. due to symmetry, half of the rolling process is modeled. the solid modeling is used in ansys to make the mesh with element type visco106 for the sheet and take into consideration the contact region which is meshed with element type target169 for rigid portion and contac171 for deformed portion. fig.(6) shows the stress distribution in the sheet during rolling process . 9. discussion the aluminum-copper alloy is considered one of high strength alloys therefore it is used in many engineering applications like aircraft structure; it requires heat treatment to improve its mechanical properties. the main object of rolling is to increase length and decrease thickness with keeping width constant. the solution heat treatment improves the mechanical properties; the rigidity increased 1.042 times, the tensile stress increased 1.028 times, the yield stress increased 1.662 times and the rolling force decreased 2.506 times. fig.6. stress distribution in the sheet during rolling process. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ hani aziz ameen al-khwarizmi engineering journal, vol. 7, no. 2, pp 14 21 (2011) 20 results are taken from this research are; rigidity and tensile strength, it is found that the solution heat treatment improves the mechanical properties for (2024-t3) alloy. by decreasing number of passing between rollers, keeping thickness and a free from strain hardening. it is found that force needed for rolling untreated sheets is greater than force needed for solution heat treated because of strain hardening. the stresses’ result in sheet b4 is bigger than that of sheet b3 , b2 , b1 respectively, due to the factor (ho-hi) is bigger in spite of the yield stress is bigger, while the stresses in sheets c1,c2,c3, and c4 is not vary significantly due to constant thickness. 10. conclusions it can be concluded the following: 1. mechanical properties for the alloy without heat treatment and rolling were good because of strain hardening. 2. mechanical properties for the alloy after heat treatment and rolling is improved 1.5% but with less force and stress compared with untreated. 3. the availability of using ansys program to make the rolling process and to show the stresses distribution in the alloy during rolling process. notation l the length of contact line between roller and sheet (mm). r radius of roller (mm). ho the thickness before rolling (mm). hi is thickness after rolling (mm). pr roller pressure (n/mm2). qp multiplication factor fr roller force (friction ) (n). w sheet width (mm). t roller torque (t.m). v linear velocity (m/sec). r roller radius (mm). greek letters ρ density (kg/m3). σ stress (n/mm2). σtm flow stress (n/mm2). ω angular velocity (rad/sec). 11. references [1] wang feng" microstructure and mechanical properties of spray-deposited al–zn–mg– cu alloy processed through hot rolling and heat treatment", 2009. [2] shahani a. r., nodamaie s.a. and salehinia i. “parametric study of hot rolling process by the finite element method”, transaction b: mechanical engineering vol. 16, no. 2, pp. 130{139, sharif university of technology, april 2009. [3] p. chandramohan, k. manikanda subramanian, p. chandrasekar “ rolling process with ohsas and texture formation– a review”, journal of engineering science and technology, vol. 4, no. 1, 1–19, school of engineering, taylor’s university college,2009 [4] johnson w. and needham g. “further experiments in asymmetrical rolling”, int. j. mech. sci., vol. 8, 1982. [5] johnson w. and mellor p.b. “engineering plasticity”, elshorwood limited, new york, 1973. [6] nagpal g.r. "metal forming processes", first edition, 1998. [7] kawałek a. “the analysis of the asymmetric plate rolling process” journal of achievements in materials and manufacturing engineering, vol.23, issue 2, august, 2007. [8] saeed moveni, “finite element analysis, theory and application with ansys”. 1999. [9] ansys – help, “structural manual”, ansys, inc., 1999. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ 21 ، صفحة2، العدد 7مجلة الخوارزمي الھندسیة المجلد ھاني عزیز أمین 14 )2011( 21 تأثیر المعاملة الحراریة المحلولیة على الخواص المیكانیكیة لسبیكة باستعمال عملیة الدرفلة (t3-2024)نحاس -ألمنیوم *** خیریة سلمان حسن ** أسماء حسن أسماعیل * ھاني عزیز أمین بغداد/ الكلیة التقنیة /ب والعددم ھندسة القوالقس * haniazizameen@yahoo.com : البرید االلكتروني جامعة بغداد /كلیة الھندسة/ ھندسة المیكانیكیةقسم ال ** asma.sawaf@yahoo.com : البرید االلكتروني بغداد/ التكنولوجیامعھد /يالقسم المیكانیك *** almaden20002000@yahoo.com : البرید االلكتروني !!!!!!!!!!!!! الخالصة ة t3-2024نحاس -دراسة تأثیر المعاملة الحراریة المحلولیة على الخواص المیكانیكیة لسبیكة ألمنیوم ة الدرفل الل عملی ة . من خ راء معامل م إج ث ت حی دن (c°480)حراریة تضمنت تسخین صفائح من ھذه السبیكة إلى درجة حرارة كیل الل ة التش راء عملی م إج دھا ت اء بع ریع بالم د الس ة (ثم التبری ى ) بالدرفل عل ة ا م دراس دھا ت ھر بع كیل ھذه الصفائح المقساة ثم إجراء عملیة تعتیق طبیعي لمدة ش ة التش راء عملی م إج ث ت الدة حی د وص ة ش ن مقاوم ة م واص المیكانیكی لخ ل دون تعام دن ب ائج للمع ة النت ددة ومقارن كیل متع ب تش ل وبنس ین درافی فائح ب ر الص الل تمری ن خ ة م ة الدرفل امج . بواسطة عملی تخدام برن م اس ansysت ة ة الدرفل ي عملی ادات ف ع االجھ ة توزی ین أن . لدراس د تب ولق الي الخ الد االنفع مى باالص ا یس بب م ل بس راري افض ل ح دون تعام بیكة ب ة للس اص المیكانیكی . والخواص المیكانیكیة للسبیكة بعد المعاملة الحراریة والدرفلة تحسنت ایضًا ولكن بجھد وقوى اقل مقارنة بتلك التي اجریت بدون معاملة this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ final1 ١ al-khwarizmi engineering journal al-khwarizmi engineering journal, vol.1, no.1,pp 1-18, (2005) neuro-self tuning adaptive controller for non-linear dynamical systems ahmed sabah abdul ameer al-araji university of technology abstract: in this paper, a self-tuning adaptive neural controller strategy for unknown nonlinear system is presented. the system considered is described by an unknown narma-l2 model and a feedforward neural network is used to learn the model with two stages. the first stage is learned off-line with two configuration serial-parallel model & parallel model to ensure that model output is equal to actual output of the system & to find the jacobain of the system. which appears to be of critical importance parameter as it is used for the feedback controller and the second stage is learned on-line to modify the weights of the model in order to control the variable parameters that will occur to the system. a back propagation neural network is applied to learn the control structure for self-tuning pid type neurocontroller. where the neural network is used to minimize the error function by adjusting the pid gains. simulation results show that the self-tuning pid scheme can deal with a large unknown nonlinearity. keyword: self-tuning, neural network, adaptive controller. 1. introduction: in many applications, the control engineers face a number of practical difficulties. the large dimensionality of many processes & the significant interaction between variables from the major obstacle to the successful attempts of extending the classical techniques for the design of controllers for monovaraible plants to multivariable ones. the development of computer-aided techniques to design controllers aim to reduce interaction before applying classical theory to the individual loops. most existing techniques are based on the design of tunable set-point tracking controllers with the dominance pi (proportional, integral) & pid (proportional, integral, derivative) controllers in industry & certain assumptions such as linearity & interactions with in the controlled process have to be made [1,2]. neural networks have broad applicability to real world problems, such as in pattern recognition,diagnostic, optimization, system identification & control. they have already been successfully applied in many industries, as they are well suited for predication or forecasting because of their abilities in identifying patterns or trend in data [3,4]. the neural network model can be used in control strategies that require a global model of the system forward or inverse dynamics, and these models are available in the form of neural networks, which have been trained using neural based system identification techniques. papers by: narandra & parthasarathy [5,6] are some of those that can be referred to as the application of neural networks for ahmed sabah abdul ameer /al khwarizmi engineering journal, vol. 1, no. 1, pp 1-18 (2005) ٢ system identification. the generalized learning method attempts to produce the inverse of a plant over the entire state space using off-line training while in the specialized architecture the training is on-line and uses error backpropagation through the plant to learn the plant inverse dynamics over a small operating region. behera et al [7] in their paper are concerned with the design of a hybrid controller structure consisting of the adaptive control law and neural network based learning scheme for adaptation of time varying controller parameters. the global stability of the closed-loop feedback system is guaranteed provided the structure of the robot-manipulator dynamics model is exact. generalization of the controller over the desired trajectory space has been established using an on-line weight learning scheme. the advantage of a neuron-adaptive hybrid control scheme is the high precision and better accuracy and computationally less intensive control scheme. also for self-tuning control (stc), chen [8] used back-propagation trained neural network within a self-tuning control system to control single-input singleoutput (siso) feedback linearizable system. another approach is given in [9], where a neural network is used to tune the parameters of a conventional controller in an on-line way. the organization of the paper is as follows: section two describes the use of fnns to learn to act as input-output model. model (narma-l2) for system identification are examined with the corresponding neural nets and learning mechanism used for this purpose. section three represents the core of the present paper. it is suggested using self-tuning pid neural controller. illustrative example that clarify the features of the proposed strategy are given in section four, where the example is discussed in detail. finally, section five contains the conclusions of the entire work. 2identification of dynamical system: the system identification and modeling is a very important step in control applications since it is a prerequisitic for analysis and controller design. due to the nonlinear nature of most of the processes encountered in many engineering applications there has been extensive research covering the field of nonlinear system identification [10]. this section focuses on nonlinear system identification using the model of multilayered feedforward neural network, narma-l2 model. the neural network is trained using backpropagation algorithm. to describe the process by using artificial neurons as basic building elements for the development of multi-layered and higher order neural network, the feedforward neural networks are widely used. the learning scheme for feedforward neural networks presented in this section includes the generalized delta rule based algorithms for error back propagation for multi-layers neural networks [11]. a feedforward neural network can be seen as a system transforming a set of input patterns into a set of output patterns, and such a network can be trained to provide a desired response to a given input. the network achieves such a behavior by adapting its weights during the learning phase on the basis of some learning rules. the training of feedforward neural networks often requires the existence of a set of input and output patterns called the training set [11] and this kind of learning is called supervised learning. the feedforward network used here has two layers, the first is the hidden layer and the second is the output layer where ahmed sabah abdul ameer /al khwarizmi engineering journal, vol. 1, no. 1, pp 1-18 (2005) ٣ each unit in the hidden layer has a continuous sigmoidal nonlinearity [12] and the output node has linear activation function. narma-l2 model identification: nonlinear input-output behavior can be well approximated by narma-l2 (nonlinear auto regressive moving average-linear) two model which can be expressed as [13]: )]1(),...,1(),1(),...,([)1( +−−+−=+ nkukunkykyfky ppp )k(u)]1nk(u),...,1k(u),1nk(y),...k(y[g pp ×+−−+−+ ...(1) where n is the order of the system. the narma-l2 model requires only two neural networks to approximate the function f and g. each of the two. functions, however has (2n-1) inputs by using narma-l2 model the weights of the neural networks are adjusted in a similar manner when using the narma model. )]1nk(u),...k(u),1nk(y),...,k(y[f)1k(y ppp +−+−=+ …(2) the difference between them is that narma-l2 model consists of two functions f[-] and g[-] in equation (1) while one neural network is needed for narma model. the first step in the identification procedure using feedforward neural network is quite straightforward with serial parallel model and at each instant of time. the past inputs and the past outputs of the system are fed into the neural network as shown fig (1). plant h h l n1= ][ − ∧ f h h l n2= ][− ∧ g 1z− 1nz +− y2 y1 training mechanism + + + 1nz +− 1z− u(k) y m (k+1) y p (k+1) fig (1): narma-l2 identification model serial-parallel configuration × ahmed sabah abdul ameer /al khwarizmi engineering journal, vol. 1, no. 1, pp 1-18 (2005) ٤ the network’s output yields the prediction error: )1k(y)1k(y)1k(e mp +−+=+ …(3) the identification model for the narma-l2 model can be better illustrated as fig.1, where x represents the input vector of the networks n1 and n2 (the argument of ][f − ∧ and ][g − ∧ ). the learning (training) algorithm is usually based on the minimization (with respect to the network weights) of the following objective cost function: ∑ ∑ = = +−+=+= np i np i i m i p i kykykee 1 1 22 ))1()1(( 2 1))1(( 2 1 … (4) where np is number of patterns, ie is the error of each step, i py is the actual output of the plant of each step and i my is the model output of the plant of each step. from fig.1, it is important to note that the error between the desired output and the estimated neural network output needed to apply a supervised learning algorithm which is not available at the output n1 and n2. hence, a little modification must be done to fit the algorithm to our case. this can be simply done by backpropagating the error at the output of the narma-l2 model (between y p (k+1) and y m (k+1)) to the output of n2 after multiplying it by u(k) and to the output of n2 after multiplying it by u(k) and to the output of n1 directly. the second step in the identification procedure using the same feedforward neural network that its learned off-line with serial –parallel model. but now with parallel model and at each instant of time, the past inputs and the past model outputs of the neural network are fed into the same neural network as shown fig.2. in order to minimize the error between the actual output & the model output and is equal to zero approximately then the model (narma-l2) will complete the same actual output response. when identification of the plant is complete then g[-] can be approximated by ][g − ∧ and f[-] by ][f − ∧ and the narma-l2 model of the plant can be described by equation (5) below: )]1(),...,1(),1(),...,([)1( +−−+−=+ ∧ nkukunkykyfky ppm )()]1(),...,1(),1(),...,([ kunkukunkykyg pp ×+−−+−+ ∧ … (5) likewise if ][g − ∧ is sign definite in the operating region then the ][g − ∧ network can be used as the jacobain of the plant as given by equation (6). )]1nk(u),...,1k(u),1nk(y),...,k(y[g pp +−−+− ∧ …(6) where the jacobain is: ][ )( )1( ^ −= ∂ +∂ = g ku ky jacobain p …(7) the sign definiteness of ][g − ∧ in the operating region (the region of interest) ensures the uniqueness of the plant inverse at that operating region [14]. now by using equation (5) as the model of the plant identifier and equation (6) as the jacobain of the plant. 3the controller design: the control of nonlinear plants is considered in this section. the approach used to control the plant depends on the information available about the plant and the control objectives. the information of the unknown nonlinear plant can be known by the input-output data only and the plant is considered as (narma-l2 model). the first step in the procedure of the control structure is the identification of the plant from the input-output data, and then is used to ahmed sabah abdul ameer /al khwarizmi engineering journal, vol. 1, no. 1, pp 1-18 (2005) ٥ find the jacobain of the plant as in section two. the feedback neural controller is used based on the minimization of the error between the desired “set-point” & the actual output plant in order to achieve good tracking of the reference signal and to use minimum effort. the integrated control structure that consists of the identifier of the plant and a self-tuning pid controller type neural networks thus brings together the advantages of the neural model with the robustness of feedback. the general structure of the neural controller type can be given in the form of the block diagram shown in fig. 3.and this structure of the proposed controller can be applied to the nonlinear plants.it consists of: 1. identifier as feedforward neural networks (narma-l2) model. 2. self-tuning pid feedback controller type neuro controller. in the following sections, the proposed controller will be explained in detail. plant h h l n1= ][ − ∧ f h h l n2= ][− ∧ g 1z− 1nz +− y2 y1 training mechanism + + + 1nz +− 1z− u(k) y m (k+1) y p (k+1) fig (2): narma-l2 identification model parallel configuration × ahmed sabah abdul ameer /al khwarizmi engineering journal, vol. 1, no. 1, pp 1-18 (2005) ٦ self-tuning pid type neurocontroller: the feedback neural controller is very important because it is necessary to stabilize the tracking error dynamics of the system when the output of the plant is drifted from the input reference [14]. the adaptive self-tuning technique is to adjust the parameters of the pid feedback controller by using neural networks, so that, the output of the plant follows the output of the predefined desired model. in the following section, a self-tuning neuro control scheme is discussed in which a neural network is used to tune the parameters of a pid controller referred to as the self-tuning pid neuro-control scheme. the pid control configuration is illustrated in fig. 4, where kp is the proportional gain, ki is an integral gain, & kd is the derivative gain, which are adjusted to achieve the desired output.the control input u(k) of the pid controller is given by equation (8): desy fig (3): the general structure of the proposed controller + _ + _ u y p y m ∆ me pid controller nonlinear plant neural network ∆ neural network identifier ∆ ∆ e kp ki kd fig (4): general configuration of pid controller ⊕ u e kp s ki kds ahmed sabah abdul ameer /al khwarizmi engineering journal, vol. 1, no. 1, pp 1-18 (2005) ٧ ∑ −−++= )1()(()()()( kekekdkekikkpeku (8) the proposed control structure for the self-tuning pid learning where the network is used to minimize the error function by adjusting the pid gain. the discrete-time version of pid controller is described by: 2)]-e(k1)-2e(k-kd[e(k) e(k) ki1)]-e(k-kp[e(k)1)-u(ku(k) ++ ++= (9) where kp, ki, & kd denote the pid gains. e(k)= )()( kyky mdes − (10) )(kydes is a desired output. )(kym is the model output. in order to derive the self-tuning algorithm of the pid controller, a cost function e should be minimize and it is defined as:: )1( 2 1 2 += kee (11) using two layers neural network as shown in fig.5, that will realize the learning rule to find the suitable pid gains. the multi-layered feedforward neural network shown in fig.5 is composed of many interconnected processing units called neurons or nodes [10]. where: v : weight matrix. w : weight matrix. l : denotes linear node. h : denotes nonlinear node with sigmoidal function. as can be seen the net consists of three layers: an input layer (buffer layer), a single hidden layer with biases and a linear output layer with bias too. the neurons in the input layer simply store the scaled input values. the hidden layer neurons perform two calculations. to explain these calculations, consider the general j’th neuron in the hidden layer shown in fig.6. the inputs to this neuron consist of an ni – dimensional vector x (ni is the number of the input nodes) and a bias whose value is “-1”[10]. each of the inputs has a weight ijv , associated with it. the first calculation within the neuron consists of calculating the weighted sum jnet of the inputs as: ∑ = + ×+×= ni i nijiijj biasvxvnet 1 1,, (12) next the output of the neuron jh is calculated as the continuous sigmoid function of the jnet as: jh = h( jnet ) (13) h( jnet )= 1 1 2 − + − jnete (14) ahmed sabah abdul ameer /al khwarizmi engineering journal, vol. 1, no. 1, pp 1-18 (2005) ٨ once the outputs of the hidden layer are calculated, they are passed to the output layer. in the output layer, a single linear neuron is used to calculate the weighted sum (neto) of its inputs (the output of the hidden layer as in equation(15). neto k = biaswhw nhk nh j jkj ×+× + = ∑ 1, 1 (15) where nh is the number of the hidden neuro (nodes) and kjw is the weight between the hidden neuron jh and the output neuron.the single linear neuron, then, pass the sum (neto k ) through a linear function of slope 1 (another slope can be used to scale the output) as: )( kk netolo = ,wherel(x)=x (16) thus the outputs at the output layer are kp, ki, & kd which are denoted by o1, o2, & o3 respectively. based on the steepest descent (gradient) method, at the output layer: fig (5): neural network is used to determine the pid gains h l jiv kjw h h inputs bias= -1 bias= -1 kp=o1 inputs layer hidden layer output layer l l ki=o2 kd=o3 ∑ h 1,jv 2,jv nijv , , +nijv jh x1 x2 xni bias = -1 fig (6): neuron j in the hidden layer. ahmed sabah abdul ameer /al khwarizmi engineering journal, vol. 1, no. 1, pp 1-18 (2005) ٩ kj kj kj w w ekw ∆+ ∂ ∂ −=+∆ αη)1( (17) kj k kkj w net net e w e ∂ ∂ × ∂ ∂ = ∂ ∂ (18) kj k k k kkj w net net o o e w e ∂ ∂ × ∂ ∂ × ∂ ∂ = ∂ ∂ (19) kj k k k kkj w net net o o ku ku e w e ∂ ∂ × ∂ ∂ × ∂ ∂ × ∂ ∂ = ∂ ∂ )( )( ( 20) kj k k k k m mkj w net net o o ku ku ky ky e w e ∂ ∂ ∂ ∂ ∂ ∂ ∂ +∂ +∂ ∂ = ∂ ∂ )( )( )1( )1( (21) jk k m mkj onetf o ku ku ky ky e w e )()( )( )1( )1( ′ ∂ ∂ ∂ +∂ +∂ ∂ = ∂ ∂ (22) ][ )( )1( ^ −= ∂ +∂ = g tu kyjacobain m (23) jk kmkj onetf o kug ky ke ke e w e ×′× ∂ ∂ ×−× +∂ +∂ × +∂ ∂ = ∂ ∂ )()(][ )1( )1( )1( ^ (24) from equation (10 & 11) substituted in equation (24) jk k ^ kj o)net(f o )t(u ][g)1t(e w e ×′× ∂ ∂ ×−×+−= ∂ ∂ (25) where: c)net(f k =′ for linear activation function with gain is limited between (0 to 1).           =−+−− = =−− = ∂ ∂ 3)2()1(2)( 2)( 1)1()( )( kkekeke kke kkeke o ku k (26) then substituted equation (25) in equation (12) kjj k kj woc o kugkekw ∆+× ∂ ∂ −+=+∆ αη )(][)1()1( ^ (27) at the hidden layer: ji ji ji v v ekv ∆+ ∂ ∂ −=+∆ αη)1( (28) ji j jji v net net e v e ∂ ∂ × ∂ ∂ = ∂ ∂ (29) j jji o net e v e × ∂ ∂ = ∂ ∂ (30) j j k 1k j j ji net o o eo v e ∂ ∂ × ∂ ∂ ×= ∂ ∂ ∑ = (31) j j j k k 1k k j ji net o o net net eo v e ∂ ∂ × ∂ ∂ × ∂ ∂ ×= ∂ ∂ ∑ = (32) )net(fw net eo v e jkj k 1k k j ji ′×× ∂ ∂ ×= ∂ ∂ ∑ = (33) from the derives of knet e ∂ ∂ in equation (19), we get: k k m k o kunetf ku kyke net e ∂ ∂ ×′× ∂ +∂ ×+−= ∂ ∂ )()( )( )1()1( (34) from equation (34) substituted in equation (37) ∑ = ′ ∂ ∂′ ∂ +∂ +−= ∂ ∂ k k jkj k k m j ji netfw o kunetf ku kykeo v e 1 )()()( )( )1()1( (35) then equation (35) substituted in equation (28) ∑ = ′ ∂ ∂ −+=+∆ k k jkj k jji netfw o kucgkeokv 1 ^ )()(][)1()1( η jiv∆α+ (36) ahmed sabah abdul ameer /al khwarizmi engineering journal, vol. 1, no. 1, pp 1-18 (2005) ١٠ 4case study: in this section, an example is taken to clarify the features of the neural controller explained in section three. in this example, the controller structure is applied to the plant whose difference equation is: )(2.1))(2(8.0)1( kukysinky pp +=+ (37) this plant has been adopted from [8 & 14]. for the open loop response of the plant )k(y p to the input signal u(k) is shown in fig 7-a and b respectively. the plant response is very oscillatory when the input amplitude 4.0)k(u ≥ . to use the proposed controller first a neural network is trained for the identification the plant dynamics. there are two stages the first is a series-parallel configuration narmal2 model identification structure as that in fig.1 is used. the model is described by: +=+ )]([1)1( kynky pm )()]([2 kukyn p (38) -1.8 -1.4 -1 -0.6 -0.2 0.2 0.6 1 1.4 1.8 0 10 20 30 40 50 60 70 80 90 100 k yp [k ] fig (7-a): the open loop response -1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1 0 10 20 30 40 50 60 70 80 90 100 k u [k ] fig (7-b): the corresponding input signal ahmed sabah abdul ameer /al khwarizmi engineering journal, vol. 1, no. 1, pp 1-18 (2005) ١١ where n1[-] and n2[-] are multilayered neural networks which approximate ][f ^ − and ][g − ∧ of equation (5), respectively. since each of n1[-] and n2[-] has three inputs )(kyp (see equation (38)), the initial guess of the number of hidden nodes is three for each network. using a random input sequence u(k) with 1)( ≤ku a training set of 100 patterns input-output used with learning rate 1η for n1 and 2η for n2 and both were taken to be equal to 0.3. during the training phase, the training set has been presented to the network many times. a training event corresponding to a single pass over of the entire training set is called a training epoch or training cycle. however, for this example after 2000 epochs the average system error (ase) computed for the latest epoch, which is described by equation (39) was 61077.2 −× . ( )∑ = +−+= np i i m i p kyky np ase 1 2 )1()1( 2 1 (39) where np total number of patterns which is equal to 100 here. fig.8-a compares the time response of the series-parallel model of equation (38) with the actual plant output for the input as a learning set. while fig.8-b compares the time response of the series-parallel model of equation (38) with the actual plant output for the input applied as testing set generated from equation (40). ) 20 2sin(5.0) 10 2sin(5.0)( kkku ππ ×+×= (40) the second stage is a parallel configuration narma-l2 model identification structure as that in fig 2 is used. to guarantee the model output is equal to the actual output and also to find the jacobain of the plant. +=+ )]([1)1( kynky mm )()]([2 kukyn m (41) where n1[-] and n2[-] are multilayered neural networks which approximate ][f ^ − and ][g − ∧ of equation (5), respectively. since each of n1[-] and n2[-] has three input )( ky m (see equation (41)). using the same random input sequence u(k) with 1)k(u ≤ a training set of 100 patterns input-output used on the same the neural networks n1[-] & n2[-] that there are learned off-line with serialparallel identification with learning rate 1η for n1 and 2η for n2 and both were taken to be equal to 0.3. during the training phase, the training set has been presented to the network many times. however, for this example after 5000 epochs the average system error (ase) computed for the latest epoch, which is described by equation (39) was 61013.1 −× . fig.9-a compares the time response of the parallel model of equation (41) with the actual plant output for the input as a learning set, while fig.9-b compares the time response of the parallel model of equation (36) with the actual plant output for the input u(k) applied as testing set generated from equation (35). also fig.10 shows a plot of the coefficient of u(k) which is ][g − ∧ for the narma-l2 models as a function of time with values computed using the corresponding network )()]([2 kukyn p , when a random input sequence u(k) with 1)k(u ≤ has been applied to the model. as shown in fig.10, ][g − ∧ is sign definite in the region of interest. this means that the plant is invertable, or in other words; the model output )1k(ym + is monotonic with respect to ahmed sabah abdul ameer /al khwarizmi engineering journal, vol. 1, no. 1, pp 1-18 (2005) ١٢ -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 0 10 20 30 40 50 60 70 80 90 100 k ym [k ] & y p[ k] fig (8-a): the response of the plant & the serial-parallel narma-l2 identification model for learning patterns plant response -----model response -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 0 10 20 30 40 50 60 70 80 90 100 k yp [k ]& ym [k ] fig (8-b): the response of the plant & the serial-parallel narma-l2 identification model for testing patterns plant response -----model response -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 0 10 20 30 40 50 60 70 80 90 100 k ym [k ] & y p[ k] fig (9-a): the response of the plant & the parallel narma-l2 identification model for learning patterns plant response -----model response ahmed sabah abdul ameer /al khwarizmi engineering journal, vol. 1, no. 1, pp 1-18 (2005) ١٣ u(k). the variation of ][g − ∧ is approximately around 1.2 as it is expected. this can be explained easily by noting the fact what ][g − ∧ resembles the plant jacobain is equal to as equation (7) and for this example 2.1 )k(u )1k(yp = ∂ +∂ . to apply the proposed structure of controller after good learning of the identifier as pm yy ≈ . it used the desired trajectory and the training done by repeating the desired trajectory cycles over 26000 times. the neural networks are used to minimize the performance error between the reference and the model output, where the model output is similar to the actual output. convergence is achieved when the performance error falls below a pre-specified value. after training, it can be observed that the actual output of the plant is following the desired trajectory and the model output is the same as the actual output in figs.11 & 12. and also, the gains of the pid selftuning neural controller as shown in fig. 13 -a, b, & c kp, ki, & kd 1.19 1.195 1.2 1.205 1.21 0 10 20 30 40 50 60 70 80 90 100 k ja co ba in o f t he p la nt fig (10): estimated plant jacobain -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 0 10 20 30 40 50 60 70 80 90 100 k yp [k ]& ym [k ] fig (9-b): the response of the plant & the parallel narma-l2 identification model for testing patterns plant response -----model response ahmed sabah abdul ameer /al khwarizmi engineering journal, vol. 1, no. 1, pp 1-18 (2005) ١٤ -1 -0.5 0 0.5 1 0 10 20 30 40 50 60 70 80 90 100 110 120 k yp [k ]& yd es [k ] fig (11): the response of the plant with the set point plant response ----set point -1 -0.5 0 0.5 1 0 10 20 30 40 50 60 70 80 90 100 110 120 k yp [k ]& ym [k ] fig (12): the response of the plant & the response of the model plant response -----model response -2.5 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 2.5 0 10 20 30 40 50 60 70 80 90 100 110 120 k k p fig (13-a): kp gain of pid controller ahmed sabah abdul ameer /al khwarizmi engineering journal, vol. 1, no. 1, pp 1-18 (2005) ١٥ fig (13-b): ki gain of pid controller -5.5 -4.5 -3.5 -2.5 -1.5 -0.5 0.5 1.5 2.5 3.5 4.5 5.5 0 10 20 30 40 50 60 70 80 90 100 110 120 k k i -2.5 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 2.5 0 10 20 30 40 50 60 70 80 90 100 110 120 k k d fig (13-c): kd gain of pid controller -1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1 0 10 20 30 40 50 60 70 80 90 100 110 120 k u [k ] fig (14): the control signal of the pid controller ahmed sabah abdul ameer /al khwarizmi engineering journal, vol. 1, no. 1, pp 1-18 (2005) ١٦ respectively. and the feedback control action as shown in fig14. 5conclusion: the structure of the neural controller with an identifier based on neural narma-l2 model that is learned offline with two configuration serialparallel & parallel and applied the algorithm of the self-tuning pid neural controller as the proposed structure of controller and successfully simulated to nonlinear system as the example. using neural narma-l2 model as a nonlinear model of the plant provides a simple check on the model jacobain, which appears to be of critical importance as it is used for the feedback controller. the on-line identifier narma-l2 model of the plant is used to updated of the weights of the identifier by using (bpa) in order to guarantee that model output approaches the actual output. using pid feedback controller with selftuning neural to adjust the parameters of the controller. so that, the output of the plant follows the output of the predefined desired input and (bp) algorithm is used to learn the model. the proposed control structure has shown the ability to minimize the error between the desired output and the actual output of the plant as well as the control action, excellent set point tracking, as it was clear when applied to the example. the simulation example in this paper is implemented using turbo c++ programming language together with microsoft excel. references 1. porter b. & jones a.h.,“ design of tunable digital set-point tracking pi controller using step response matrices for gas turbain” alaa guidance, naving – 1986. nomenclature abbreviations 2. porter b. & jones a.h.,“ genetic tuning of digital pid controllers” electronics letters: vol. 28, pp 843-844, 1992. ase average system error bpa back propagation algorithm fbnc feedback neural controller ffnc feedforward neural controller narma nonlinear auto regressive moving average pid proportional integral derivative siso single-input single-output stc self-tuning control symbol description e summation of error e the error between reference input and the model output ][2],[1 ],[],[ −− −− ∧∧ nn gf neural input-output mapping functions h sigmoidal activation function of the hidden nodes k discrete time instant l linear activation function of the output node n plant order jnet the weighted sum of the inputs of the node j in the hidden layer neto the weighted sum of the inputs of the output node nh number of nodes in hidden layer ni number of nodes in input layer u manipulated input v weight matrix between the input and the hidden layer w weight matrix between the hidden and the output layer x the input vector for the input layer desy the desired output py plant output my model output p number of patterns in the training set η learning rate of the neural network ahmed sabah abdul ameer /al khwarizmi engineering journal, vol. 1, no. 1, pp 1-18 (2005) ١٧ 3. patterson d.w. “artificial neural networks, theory & applications” prentice hall 1996. 4. lightbody g. and irwin g.w.” direct neural model reference adaptive control” ieee proce. on control theory and applications, vol. 142; no. 1, pp. 31-42; jun 1995. 5. k. s. narendra and k. parthasarathy, “identification and control of dynamical systems using neural networks,” ieee trans. neural networks, vol. 1,pp. 4-27, 1990. 6. k. s. narendra and k. parthasarathy, “gradient methods for the optimization of dynamical systems containing neural networks,” ieee trans. neural networks, vol. 2 no. 2, pp. 252-262, 1991. 7. l. behera, s. chaudhury, and m. gopal, “neuro-adaptive hybrid controller for robot-manipulator tracking control” iee proc. control theory appl. vol.143, no. 3, pp.270275, 1996. 8. f. c. chen, “back-propagation neural networks for nonlinear selftuning adaptive control,” ieee control systems magazine, vol. 10, no. 3, pp. 44-48, 1990. 9. s. omatu, m. khalid, and r. yusof, neuro-control and its applications. london: springervelag, 1995. 10. s. a. billings, “identification of nonlinear systems a survey,” iee proc., vol. 3,pp. 272-285,1980. 11. n. b. karayiannis and a.n. venetsanopoulos, artificial neural networks learning algorithms, performance evaluation, and applications. london: kluwer academic publishers. 1993. 12. k. j. hunt, d. sbarbaro, r. zbikowski and p. j. gawthrop, ”neural networks for control systems—a survey,” automatica, vol. 28, no. 6, pp. 1083-1112, 1992. 13. k. s. narendra and s. mukhopadhyay, “adaptive control using neural networks and approximate models,” ieee trans. neural networks, vol. 8, no. 3, pp. 475-485, 1997. 14. ahmed s. al-araji “a neural controller with a pre-assigned performance index” m.sc. thesis, university of technology, november 2000. ahmed sabah abdul ameer /al khwarizmi engineering journal, vol. 1, no. 1, pp 1-18 (2005) ١٨ المسيطر المتكيف ذو التنغيم التلقائي العصبي لالنظمة الديناميكية الالخطية احمد صباح عبد االمير االعرجي لوجيةوالجامعة التكن :الخالصة يتم تعليمه بطريقة (narma-l2) الذي أساسه النموذج العصبي (identifier) أن هيكلية المسيطر العصبي مع المعرف (off-line) مع صيغتين التوالي المتوازي و المتوازي وتطبيق خوارزمية التنغيم التلقائي العصبي للمسـيطر (pid) كمقتـرح .لبناء هيكلية المسيطر (jacobain)هو نموذج ألخطي يصف المنظومة ألالخطية ويسـتخدم لتحقـق مـن (narma-l2)أن النموذج العصبي .منظومة و التي تعتبر من العناصر المهمة و الحرجة في إيجاد إشارة التغذية العكسيةلل للنموذج بطريقة خوارزمية االنتشار (weights)لتحديث األوزان (on-line)يتم أيضا تعليمه (narma-l2)أن المعرف .العكسي العامة لكي يصبح النموذج مطابق الى المنظومة ألالخطية لكي يتبع إخراج المنظومة الحقيقية (pid ) يطر الراجع العصبي ذات التنغيم التلقائي لتعبير عناصر المسيطر يستخدم المس .خوارزمية االنتشار العكسي العامة" اإلدخال المطلوب وباستخدام أيضا .للمنظومةأن هيكلية المسيطر المقترح يستخدم لتقليل الخطاء بين اإلخراج المرغوب و اإلخراج الحقيقي .لقد تم الحصول على نتائج ممتازة باستخدام المسيطر المقترح عندما طبق هذا المسيطر على المنظومة ألالخطية رنا ضياء al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 8, no. 3, pp 40 52 (2012) design a security network system against internet worms rana dhia'a abdu-aljabar department of information and communication engineering/ college of information engineering/ university of al-nahrain (received 5 september 2011; accepted 4 march 2012) abstract active worms have posed a major security threat to the internet, and many research efforts have focused on them. this paper is interested in internet worm that spreads via tcp, which accounts for the majority of internet traffic. it presents an approach that use a hybrid solution between two detection algorithms: behavior base detection and signature base detection to have the features of each of them. the aim of this study is to have a good solution of detecting worm and stealthy worm with the feature of the speed. this proposal was designed in distributed collaborative scheme based on the small-world network model to effectively improve the system performance. keywords: worm detection, behavior base, signature base, signature generation. 1. introduction a computer worm is a self-replicating computer program. it uses a network to send copies of itself to other computer terminals on the network and it may do so without any user intervention. currently, worms are serious security threat that may cause congestion in the network which leads to large queuing delays, and high packet loss. since code red and nimda worms were spread in 2001, epidemic-style attacks have caused huge damages. the internet is an influential function in the economy and reckon mainstay to the life. once the internet is broken down, it will cause a huge economic loss. so the worm handling must be automatic in order to have any chance of success because worms spread too fast [1]. the main difference between viruses and worms is the method in which they reproduce and spread. a virus is dependent upon a host file or boot sector, and the transfer of files between machines to spread, while a worm can run completely independently and spreads itself through network connections. [2]. intrusion detection systems (ids) serve three essential security functions: they monitor, detect, and respond to unauthorized activities. there are two basic types of intrusion detection: host-based and network-based. host based idss examine data held on individual computers that serve as hosts, while network-based idss examine data exchanged between computers [3]. false positive (fp) and false negative detection errors are inevitably generated in any practical detection system [4]. a false positive indicates a normal string that is incorrectly identified as an alarm (suspicious string). a false negative means missing the detection of a suspicious string by incorrectly labeling a worm (or suspicious string) as a normal one [5]. ideally, a perfect detection system would generate no false positives and no false negatives and would only raise an alarm when the actual worm is detected. in recent years, efficient defense against distributed attacks has been a hot topic in network security community. instead of establishing brand-new, dedicating systems, collaborating widely deployed, single-point network security applications for co-defense would be more feasible. through collaboration, a security shield that covers infrastructure of multiple network domains could be built without significant modification. besides keeping most of original functions, collaboration offers individual security applications wider views of dynamic situations around which otherwise may not be observed. it rana dhia'a abdu-aljabar al-khwarizmi engineering journal, vol. 8, no.3, pp40 -52 (2012) 41 improves the resilience and confidence of participating security applications to handle sophisticated security problems in optimized strategies. existing collaborative schemes for distributed defense could be classified into either centralized or decentralized category. this paper obtained a hybrid solution between behavior base and signature base distributed over a multi sensor in the network in decentralized collaborative scheme to get a good solution for a worm attack. the remainder of this paper is organized as follows: section2 describes related works. section3 shows the proposed design scheme. section4 explains the internet worm activity in the network. section 5 explains how the behavior base algorithm builds. section 6 illustrates the signature generation briefly. section 7 discussed the central alarm work. section 8 shows the results of this design. section 9 concludes the proposed mechanism and section 10 the references. 2. related work most recent research on detecting worms concentrates on propagation modeling. defending against them remains a challenge due to their continuous evolution. the defense against worms is still an open problem. x. yang et al. [6] built algorithm for detecting the worm which has two sub algorithms, the first algorithm “short term algorithm” run well to detect worm, but the second algorithm “longer term algorithm” cannot detect some types of the stealthy worm. the algorithm also cannot hold any equations to determine specification when the equation runs in the algorithm to detect early worm if it has higher rate for value in average of failure connection. yang algorithm focuses just on detecting which computer contain the worm. m.m. rasheed et al.[7] technique is concerned with detecting the internet worm and stealthy internet worm using their behavior. it is an improvement of x. yang et al algorithm. the average of failure connections by using artificial immune system (ais) is the main factor that his technique depends on in detecting the worm. they showed that their algorithm can detect new types of worms and that intelligent failure connection algorithm (ifca) operation is faster than traditional algorithm in detecting worms. s. behal et al.[8] analyzed the outbound traffic; i.e. extrusion traffic only instead of intrusion traffic. they conclude that only extrusion or intrusion detection is not sufficient to make a network secure but rather these two approaches complement each other to make a network more secure from the threats of malware. it is widely believed that content-signaturebased intrusion detection systems (idses) are easily evaded by polymorphic worms, which vary their payload on every infection attempt. in [9] polygraph, a signature generation system that successfully produces signatures that match polymorphic worms is presented. polygraph generates signatures that consist of multiple disjoint content substrings. in doing so, polygraph leverages their insight that for a real-world exploit to function properly, multiple invariant substrings must often be present in all variants of a payload; these substrings typically correspond to protocol framing, return addresses, and in some cases, poorly obfuscated code. it contributes a definition of the polymorphic signature generation problem; propose classes of signature suited for matching polymorphic worm payloads; and present algorithms for automatic generation of signatures in these classes. it's evaluation of these algorithms on a range of polymorphic worms demonstrates that polygraph produces signatures for polymorphic worms that exhibit low false negatives and false positives. zero-day polymorphic worms pose a serious threat to the security of internet infrastructures. given their rapid propagation, it is crucial to detect them at edge networks and automatically generate signatures in the early stages of infection. in hamsa[10], a network-based automated signature generation system for polymorphic worms. evaluation based on a range of polymorphic worms and polymorphic engines demonstrates that hamsa significantly outperforms polygraph [9] in terms of efficiency, accuracy, and attack resilience. in recent years, efficient defense against distributed attacks has been a hot topic in network security community. there are two popular collaboration schemes. schnackenberg et al. proposed a centralized coordinative scheme called citra [11] for network intrusion detection in 2001. a central coordinator responds for coordinating countermeasures based on a complete view of the network. janakiraman et al. [12] introduced a decentralized defense scheme for network intrusion prevention. information is shared among trusted peers to guard the network against intrusion. the subscription-based group communication is conducted over a p2p architecture, which brings excellent scalability. rana dhia'a abdu-aljabar al-khwarizmi engineering journal, vol. 8, no.3, pp40 -52 (2012) 42 taking advantages of the p2p network, researchers attempted to address the major challenges in large scale collaboration: the scalability and avoidance of central point of failure [13]. they merged multi-dimensional correlation for collaborative intrusion detection [14], and developed self-protecting and selfhealing collaborative intrusion detection architecture for the trace-back of fast-flux phishing domains [15]. 3. the whole proposed system scheme this paper used distributed collaborative scheme based on the small-world network model. the design of small-world network model obtained a hybrid solution between behavior base and signature base by using signature generation to have a signature of the unknown worm detected by behavior base and update the database of signature base. the signature-base is distributed over a multi sensor (see figure 1) in the network to get a good defense for a worm attack. fig. 1.the small world network model for worms' detection . one of the sensors has in addition to signature base detection thread, a behavior-base detection thread, a signature generation thread, a monitoring traffic thread and a central alarm procedure. this sensor is named a central analyzer (ca). this multiple small world networks model is like figure 1 connected with each other through (ca) in decentralized scheme (see figure 2) to improve the performance by efficient defense against distributed attacks. the decentralized scheme is much flexible. it behaves similaryl to the manners of peer-to-peer (p2p) networks. this is due to the fact that most of decentralized schemes are developed on top of p2p network protocols [16]. the p2p collaborative architecture gives decentralized schemes good scalability. theoretically, any network node features compatible collaboration protocols could participate, so that the boundary of covered network could be loose. rather than having a collaborative server in centralized scheme, each participating node takes responsibilities for collaboration, as shown in figure 2, which brings more flexibility for selfmanagement. obviously, the cost for application is relatively low, since it does not require any modification in network beyond the installation of software. when the worm detected by the behavior-base thread it will send the source address (src.add) and source port (src.port) that the worm was use it, for both central alarm procedure responsible for alarming all sensors of its network and other cas (section 7), and the signature generation thread (section 6). the signature generation thread search in the suspensions list generated from monitoring traffic thread (section 6.1) is on the record that has the same src.add and src.port that the behavior-base fig. 2. decentralized collaboration. colopration ca2 can ca1 rana dhia'a abdu-aljabar al-khwarizmi engineering journal, vol. 8, no.3, pp40 -52 (2012) 43 sends them to it. from this record it will extract the worms samples to generate the new worm signature (section 6.2), and then it will send it to the central alarm procedure, which responsible for updating all database signature base for all sensors of its network and other cas and motivates the signature base to make immediate scan to the all nodes it responsible for. 4. worm scan activity worms spread many connection requests to propagate itself and infect vulnerable hosts on the internet. when selecting target hosts, worms use a kind of scanning strategies. code red and sql slammer used random scanning method, and blaster was a sequential scan worm. in [17], wu et. al. introduced a selective random scan and a routable scan worm. when a host makes a connection request via tcp, it sends a syn packet to a destination address. a connection fails if the destination address does not exist or the destination port is not open. specifically, if a syn packet is sent to an unused ip address, an icmp host which is unreachable packet is returned (see figure 3); if a syn packet is sent to a used ip address with destination port closed, a tcp reset packet is returned (see figure 4). fig. 3. destination ip address does not exist. fig. 4. destination port closed. if a worm uses random or sequential scanning to prove target hosts, the packets generated by the worm can reach unused ip addresses. in other words, the number of hosts in local network, which are targeted by the worm, largely increases. in case of normal traffic, some internal hosts are related to a specific port number. by checking the number of distinct destination addresses of inbound traffic with the port number, we find an abnormal pattern caused by a worm. the slammer worm, for example, caused some infected hosts to send up to 30,000 scans at a second [18]. the life of a worm, after it is released, typically includes the following phases: target finding, worm transferring, worm activation, and infection. during the phase of target finding and worm transferring, the worm is active over the internet, making it possible for network-based intrusion detection systems to catch the worm. the activities in the two latter phases are limited to local machines and are harder to detect by network-based intrusion detection systems [19]. 5. detection based behavior algorithm this paper adopted the intelligent failure connection algorithm (ifca) design [7]; it is an improvement of improved two rotations (itr) algorithm [6] to detect the worms. it works in first phase of worm's life which is target finding. in this phase the behavior of worm different from normal user. comparing with worm activities that scan hundreds of different ip address per second, normal users usually connect to different ip address and web sites at a slower rate. particularly, normal users may have the favorite web sites list, and don’t produce so many attempts to connect to random addresses. based on the fact that tcp-based worm will attempt tcp connections to different random addresses and result in a large number of connection failures, the traditional worm detection approach mainly focuses on the tcp syn or icmp host unreachable packets. in order to make the algorithm more accurately, a better alternative method is to monitor inbound icmp host unreachable and tcp reset packets. the ifca only records the number of inbound first failed connection packets such as icmp and tcp reset packets returned from the external destination address to the internal forged and monitored source ip address. if normal connection is received; i.e., tcp syn/ack, “counter” will be decreased. only the first failed connection sent from the forged source rana dhia'a abdu-aljabar al-khwarizmi engineering journal, vol. 8, no.3, pp40 -52 (2012) 44 ip address to different destination ip address is recorded. normal network activities are considered to decrease the counter’s value. ifca will remove the “counter” every three days. the packet should be ignored when the destination ip is recorded into the counter table. this mechanism records the number of failed connection packets such as icmp and tcp reset packets that are returned from the external destination address to the internal forged. it monitored source ip address based in the router. once detecting the first failed connection packets, the algorithm then extracts (the source address, source port, destination address, destination port) from the packet and creates the record. in this algorithm, several new equations are applied to detect the worm. it is supposed β =100 and then x= (1 to n) average of failure connection in one minute. threshold can be processed by the following equation: sum. of threshold=2 (̂6.65+0.050054(β-x)) the equation depends on the average of failure connection to compute the threshold. ifca can detect the worm early in usual time. but if the worm cannot be detected in early stage, the algorithm provides more time and new threshold to detect the worm. t1=(sum. of threshold/average of failure connection) t2= (time now – time start of the algorithm) ifca is dynamic in detecting the worm because it calculates the threshold every time. ifca detects the worm by comparing t1 to t2 as follows: if (t2 is small or equal to t1) and (the counter is greater than or equal to the summation of threshold) the worm is detected. check t1, t2. if (t2 is greater than t1), then go to feed back and decrease the average with new calculate to give other chance to detect the worm. if t1 is smaller than t2, then forward the traffic because it is a normal connection. whenever the counter value does not exceed the threshold during time cumulative computation phrase, the traffic sent from the corresponding ip address would be forwarded as normal activity (see figure 5). when the worm is detected the signature generation will run to find the signature of this worm. as it explained in the next section. fig. 5. the flow chart of the ifca. rana dhia'a abdu-aljabar al-khwarizmi engineering journal, vol. 8, no.3, pp40 -52 (2012) 45 6. signature generation in previous section unknown worm is detected by its behavior. it is a very useful way, but it still has an overload because it still needs to repeat this algorithm each time to the same worm. so this paper it suggests to have full benefit of this algorithm by generating the signature of the worm that has been detected. 6.1. traffic monitor the traffic-monitor thread catches all inbound and outbound data packets only and stores them in a list called suspicions list. from each packet it takes the source address, source port, destination address, and data and stores them in the suspicions list as record fields (figure 6). fig. 6 . suspicions list record fields. fig. 7. creating the suspicions list. after the tcp connection success; data packets will be send; these packets may be a worm packet. this thread will save all packets in a suspicions list till the threshold exceed or time over in behavior base threat then the suspicions list will be cleared and tried again. if the threshold exceeds, it means that there is a worm found by behavior base thread. so the suspicions list must be copied to signature generation thread and then will be cleared. this process is illustrated in figure 7. 6.2. signature generation algorithm a signature algorithm is a method for signing a message stored in electronic form. as such, a signed message can be transmitted over a computer network. it represents hand-written signature on the paper. its main method is to specify the person who is responsible for the documents. but digital signature scheme is superior to hand –written signature in that it is none-forge but easier identification [20]. the generated signatures used are in the form of simplified regular expression (sre). it will also define a “more specific than” relation on this signature model that allows two signatures to be compared to determine if one is a more specific form of the other [21]. it use this relation to analytically define “the most specific” signature for a polymorphic worm, and hence, formalize the problem of signature generation for polymorphic worms. based on the concept of the most specific signature, it proposed a signature generation algorithm using multiple sequence alignment. the generated signature is represented in sre, which is effective and precise because of its successful one-byte invariant extraction and emphasis on the order and distance of extracted invariant parts. in this section, it focuses on generating accurate signatures for a polymorphic worm. it will propose a more precise signature type, the sre signature, and it will briefly introduce a signature generation method based on multiple signature alignment (msa). finally it will compare the sre with other signature types. 6.2.1. sre signature type motivated by the insufficiency of current signature types for expressing distance restriction, the sre signature type designed from regular expression. it is believed that regular expression has significant advantages for intrusion detection in terms of flexibility, accuracy, and efficiency rana dhia'a abdu-aljabar al-khwarizmi engineering journal, vol. 8, no.3, pp40 -52 (2012) 46 [22]. regular expressions have been widely used in intrusion detection systems, for example, in snort and bro. however, the full regular expression is too complex and its numerous syntax rules are not needed for worm detection. hence, it introduces the simplified regular expression as a way of representing worm signatures. an sre signature is a simplified form of a regular expression that contains only two qualifiers, “.*” and “.{k}.” these can each be further abbreviated by replacing “.*” with “*”, which represents an arbitrary string (including a zero length string), and by replacing “.{k}” with “[k],” which represents a string consisting of k arbitrary characters. for example, “‘one’[2]‘two’*” is an sre signature that is equivalent to the regular expression “one.{2}two.*”. suppose that ф={*,[k]} is the set of the two qualifiers and ∑+ is the set of nonempty strings over a finite alphabet ∑. an sre signature is defined as follows: definition 1 (sre signature). an sre signature is a signature in the form of (q0)s1q1s2 . . . qk-1sk(qk), where qi ф is a qualifier, si ∑+ is a substring (i [0; k]), and(q0) and (qk) mean q0 and qk are optional. the length of an sre signature define as the total number of characters in substrings plus the number of qualifiers, and use |x| to denote the length of an sre signature x. for example, given an sre signature x = “*‘a’[2]‘bbb’[1]‘cccc’*”, |x|= 11 (1 2 3 1 4). compared with the previous signature types to be used for worm detection, the sre signature type is a more precise signature presentation because it can express distance restrictions of adjacent invariant parts using qualifiers (e.g., [k] shows the distance of k bytes). in addition, sre signatures, in the form of regular expressions, can be easily converted into existing intrusion detection system (ids) rules, and vice versa. this is illustrated in section 6.2.3. 6.2.2. sre signature generation the approach comprises three main steps: multiple sequence alignment, noise elimination and signature transformation. it first transforms a set of samples (network flows) of a polymorphic worm into a set of character sequences, and then generate an sre signature for this worm. figure 8 illustrates the procedure. ‘wormsample1’ (‘‘onewertwotyjfthreecxbfd’’) to ‘wormsample6’ (‘‘yuiddonensddtwoweredsthreenfg’’) are six worm samples and ‘noise1’ and ‘noise2’ are two noise samples. the first step analyzes and aligns these worm samples and noise flows. the alignment is represented as a colored matrix, where the greater the number of identical characters in a column, the darker its color. the next step is to identify noise samples using a noise elimination algorithm. figure 8 shows sequences ‘noise1’ and ‘noise2’ correctly identified as noise flows. the remaining sequences are recognized as worm samples. from them, identical characters in the same columns are extracted as invariant bytes of the polymorphic worm. step 3 produces an sre signature ‘‘*‘one’[4]‘two’*‘three’*’’ by putting distance restrictions between adjacent invariant bytes. this is the most specific signature of the worm. this approach steps will explained briefly bellow: step 1: multiple sequence alignment (msa) sequence alignment compares pair or multiple sequences by searching for a series of individual characters or character patterns that are in the same order in the sequences. the definition of multiple sequence alignment is given in definition 2. an alignment (result) is represented as a matrix a and the row ap within the matrix represents the aligned sequence of sp. gaps (‘–’) are inserted between elements so that elements with identical characters from different sequences can be aligned in the same columns. as can be seen in figure 8, it use colors to indicate how many rows containing an identical character for each column of a. columns with more rows are filled with a darker color. definition 2. (multiple sequence alignment.) given a family of sequences s ={s1; .; sk} over an alphabet ∑, |sp| is the length of the sequence sp, and an alignment of sequences in s is a (k× n) matrix a = (ap;i)1≤p≤k;1≤i≤n with max1≤p≤k |sp| ≤ n ≤ ∑1≤p≤k |sp|, if and only if: 1. ap, i ∑ {‘–’} (where ‘–’ ∑ is called a gap); 2. upon removal of all blanks, row ap = (ap, i) 1≤i≤n reduces to sp; and 3. no column consists only of blanks. step 2: noise elimination owing to imperfect suspicious flow classification or worm sample clustering, there may be noise in worm samples. this step finds the noise and removes it. as can be seen in figure 8 (step 2), sequences (rows in matrix) identified as noise do not have ‘*’ at the end of the sequence name, but the sequences identified as worm samples do. rana dhia'a abdu-aljabar al-khwarizmi engineering journal, vol. 8, no.3, pp40 -52 (2012) 47 imperfect suspicious flow classification or worm sample clustering can produce noise in worm samples which must be eliminated to derive accurate worm signatures. since msa in step 1 generates maximum element matches from each pair wise alignment, a limited number of noise flows will not influence the extraction of most common characters. that is, most worm samples can be aligned to get valuable matches even if there are a few noise flows. there are two noise samples at step 1 in figure 8, yet the six worm samples are properly aligned to show extractable common invariant parts. the proposed noise elimination algorithm is designed to improve the accuracy of signature generation in a noise-tolerant way. given the alignment of k sequences, it defines a noise tolerance rate (0≤ ≤1); and selects [k ] sequences as noise within k sequences. the remaining k – [k ] sequences will be regarded as worm samples and it will use them to output the final sre signature. the noise elimination algorithm first determines the invariant bytes of a polymorphic worm. the invariant bytes will be characters that appear more than [k. ] times in one column. then we determine [k. ] noise samples as those containing fewer invariant bytes. the noise elimination algorithm is shown briefly in [23]. the selection of the noise tolerance rate is a key point in the noise elimination algorithm. a fixed value of could be impractical. if is too small, some noise may not be filtered out. in contrast, if is too large, some worm samples may be wrongly eliminated as noise and there will be not enough worm samples left. in both cases, the approach may fail to generate accurate signatures. it use an adaptive scheme that changes its value according to the total number of available sequences (k, and k is required to be over 4), as shown in formula (1). the objective of this scheme is to ensure that for any k (k > 4), k [0.8k – 3.2] sequences will be chosen as noise, k k = k(1 ) 4 + [20%(k – 4)] sequences will be chosen as worm samples. in other words, at least 4 sequences will be chosen as samples. for the remaining k -4 sequences, it chooses 20% as samples (80% as noise), a conservative policy. = 0.8 – 3.2/k (k > 4) ...(1) fig. 8. sre signature generation steps. rana dhia'a abdu-aljabar al-khwarizmi engineering journal, vol. 8, no.3, pp40 -52 (2012) 48 step 3: sre signature transformation from alignment result an alignment result can be easily transformed into an sre signature. given an alignment of multiple worm samples, after the noise elimination and invariant byte extraction, it can get the distance restriction for adjacent invariant bytes by counting the number of in-between noneblank positions. taking figure 8 as an example, the corresponding sre signature is ‘‘[0,6]‘one’[4]‘two’[1,6] ‘three’[1,5]’’, where ‘[1,6]’ is a distance bound restriction meaning that there are at least one and at most six elements between ‘two’ and ‘three’ in worm samples (wormsample1–wormsample6). although using ‘[k1, k2]’ to express a distance bound restriction (instead of ‘*’ in sre signature) is a more precise way to express the range distance restriction, this algorithm [23, 24] does not adoptsuch a distance bound restriction in generated signatures. this is because even though there are some range distance restrictions in polymorphic worms that can be exactly expressed by a bound of ‘[k1, k2]’, it may not be able to extract a perfect bound given inadequate worm samples. for instance it is supposed that a polymorphic worm should have a real range distance restriction with the bound of ‘[1, 100]’. if the worm samples are inadequate, as a result, it may only gets an overspecific bound, like ‘[12,50]’, which will result in a high false negative rate. the last step in this approach outputs sre signatures by extending each range bound of‘[k1, k2]’ to ‘*’; i.e., extending ‘‘[0,6]‘one’[4]‘two’[1,6]‘three’[1,5]’’ to ‘‘*‘one’[4]‘two’* ‘three’*’’, as in figure 8. note that it still keeps the fixed distance restriction in generated sre signatures (like [4] in figure 8). fig. 9. one version of polymorphic code red ii worm. 6.2.3. compared sre with other signature types. it is natural to ask what is "a more accurate" and what is "the most accurate" signature for a polymorphic worm. intuitively, "the most accurate" signature should be "the most specific," that is, in a balance of specific and general: specific—it contains as many features of the worm as possible so that it will not lead to false positives; general—it does not contain any useless or incorrect features of the worm so that it will not lead to false negatives. definition 3 (containment, ) let x and y be two sre signatures, it says that y contains x, denoted by x y, if l(x) l(y). that is, the strings that match signature x must also match signature y. definition 4 (more specific than, ). let x and y be two sre signatures. if x y and |x| > |y|, it says that x is more specific than y, or y is more general than x, and this is denoted by x y. here are some examples for definition 3 and definition 4: “‘abc’*‘bcd’” “‘ab’*‘cd’”, “‘ab’[2]‘cd’” “‘ab’*‘cd’”; “‘aaa’*‘b’” “‘aa’*‘b’”, “‘aa’[3]‘c’” “‘aa’*‘c’”. note that if a network flow f (as a special sre signature with only one substring and without qualifiers) matches an sre signature x, it also uses “f x” to denote it. for instance, the flow “abcdef” matches “‘ab’*‘ef’” can be denoted by “abcdef” '''ab'*'ef'''. definition 5 (signature of a polymorphic worm, <∙ ). given a polymorphic worm w, if all possible samples of w match an sre signature x, then x is a signature of w, and this is denoted by w <∙ x. definition 6 (the most specific signature of a polymorphic worm, mssig). given a polymorphic worm w and its sre signature x, if w <∙ x and for any other sre signature x' such that both w <∙ x' and x x' hold, then x is the most specific signature (mssig) of w, and this is denoted by x = mssig(w). rana dhia'a abdu-aljabar al-khwarizmi engineering journal, vol. 8, no.3, pp40 -52 (2012) 49 from the above definitions, now it can answer "what is a more accurate signature" for a polymorphic worm and are able to compare the accuracy of two signatures. suppose that both x and y are signatures of a polymorphic worm w (w <∙ x and w <∙ y). signature x is more accurate than y if and only if x ≺y. given a number of samples of a polymorphic worm, the signature generation problem is formalized by the problem bellow: problem (the most specific signature generation for a single polymorphic worm). input: s1; . . . ; sn are n samples of a polymorphic worm w. output: a signature x such that x =mssig(w). given the polymorphic code red ii worm in figure 9, it can convert the generated signatures by previous nsg methods into the defined sre signature format. honeycomb [25] outputs “*‘.ida?’*”. polygraph [9] outputs “‘get / ’*‘.ida?’*‘xx’*‘%u’*‘%u780’*‘http/1.0\r\n’”. hamsa[10]outputs “‘get/’*‘.ida?’*‘%u’*‘%u780’ *‘http/1.0\r\n’*”. if these sre signatures are denoted by x1;x2, and x3, all of them are signatures of the worm according to definition 5. however, none of them is the most specific signature according to definition 6 because given an sre signature y = “‘get /’*‘.ida?’*‘xx’*‘%u’[4]‘%u780’*‘= ’[1]‘http/ 1.0\r\n’”, obviously, y x1, y x2, and y x3. that is, y is more specific than x1, x2, x3. this implies that the signatures generated by the previous methods are not “the most accurate”. 7. the central alarm procedure when the worm has been detected by the behavior-base thread it send to central alarm procedure the source address (src.add) and source port (src.port) that the worm was use it. the central alarm procedure will register the address that have a worm and send an alarm message to all sensors to not accept any data from this src.add and src.port till the signature generation generate the signature of that worm. when the signature generation thread finishes the signature, it gives it to center alarm procedure to send it to all sensors to update their database signature-base even to his signature-base database. and it motivates the signature bases to immediately scan in the new detecting worm for all computers it is responsible for. 8. the result the ifca has a good result in detecting the worms and it is interested in finding the stealthy worms. but because the ifca needs to repeat detecting all worms even it previously found it so it cause an overload on its algorithm runtime. suppose that there are n samples, each having a length l, the total time complexity of the sre [23] is o (n2l2) o (nl2). this proposal overcome the overload in both algorithms by using a hybrid solution to minimize the overall runtime; it used the ifca to detect the unknown worms then it takes the worms samples that it collecting using traffic monitor thread to generate the signature that it will be used by signature base. by using signature base in detection the same worms if they appear again it will overcome the overload in ifca. each of ifca and the signature generation are built as threat to run in parallel, so it overcomes the time complexity in sre algorithm. in signature accuracy it is found that from section 6.2.3 that the tested code red ii worm in polygraph algorithm lost ‘‘=’’ and the distance restrictions of invariant parts and in hamsa algorithm lost ‘‘=’’, the order and the distance restrictions of invariant parts in sre signature, that it adopted in this design, is not missed. in this design all data (inbound or outbound) are under monitoring using traffic-monitor thread (section 6.1) and it detects the known and unknown worms, so it overcomes the drawback of s. behal el al.[8] design. from the above it seen that the proposal design offer many features in detecting unknown and stealthy worms, the high speed in worm detecting, the most signature accuracy and finally the improvement in its performance by using a distributed collaborative scheme in it defenses against the worms attack. 9. conclusion and scope for future work this paper uses a hybrid solution between the two detection algorithms; behavior based algorithm; to have it feature in detecting unknown worms and signature base algorithm to have its speed in detecting. in behavior base detection it used ifca algorithm which it faster in detecting the worm than other traditional failure connection algorithms. also, the algorithm can detect the stealthy worms. and it used sre algorithm in rana dhia'a abdu-aljabar al-khwarizmi engineering journal, vol. 8, no.3, pp40 -52 (2012) 50 signature generation and it shows how it is the most accurate in finding the signature. a new method is built for collecting the data in a temporary list to have adequate samples for signature generation. this design used distributed collaborative scheme based on the small-world network model to improve the system performance comparing to single-point defense scheme. this paper proposed a design just for detecting the network worms. future research will work on studying the protection of the network against worms and cascading failures using a link isolation strategy based on the quarantining of susceptible clusters in the network (modularity partitioning). this strategy aims to maximize the epidemic control while minimizing the impact on the clusters performance. 10. references [1] m. costa, j. crowcroft, m. castro, a. rowstron, l. zhou, l.zhang, and p. barham, “vigilante: end-to-end containment of internet worms”, in proc. of the 20th acm symp. on operating systems principles (sosp), brighton, uk, oct 2005. 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[6] x. yang, j. lu, y. zhu & p. wang. “simulation and evaluation of a new algorithm of worm detection and containment”. proceedings of the seventh international conference on parallel and distributed computing, applications and technologies (pdcat'06), taiwan, dec 2006, pp. 448-453. [7] mohammad m. rasheed, norita md norwawi, osman ghazali, and mohammed m. kadhum, "intelligent failure connection algorithm for detecting internet", ijcsns international journal of computer science and network security, vol.9 no.5, may 2009. [8] s. behal and k. kumar, "an experimental analysis for malware detection using extrusions", (iccct) 2'nd international conference on computer and communication technology, pp. 474-478, 2011. [9] j. newsome, b. karp, and d. song, “polygraph: automatically generating signatures for polymorphic worms,” proc. 2005 ieee symp. security and privacy, pp. 226-241, 2005. 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[25] c. kreibich and j. crowcroft, “honeycomb—creating intrusion detection signatures using honeypots,” proc. second workshop hot topics in networks (hotnets ii), 2003. )2012( 40 52، صفحة 3، العدد 8مجلة الخوارزمي الھندسیة المجلد رنا ضیاء عبد الجبار 52 تصمیم نظام شبكة آمن ضد دیدان االنترنیت رنا ضیاء عبد الجبار النھرین جامعة/ كلیة ھندسة المعلومات الخالصة ، tcpھذه الورقة مھتمة بدودة االنترنیت التي تنتشر عن طرق . ركز علیھا الدیدان الفعالة شكلت تھدید رئیسي لالنترنیت، وكثیر من جھود البحوث ھي تظھر طریقة تستخدم حل ھجین بین خوارزمیتي كشف، اعتماد كشف السلوك وأعتماد كشف التوقیع . بیة حركة العمل على االنترنیت الذي یعتبر أغل ھذا االقتراح صمم بمخطط . الشبحیة بمیزة السرعة والدودة اكتشاف الدودةن ھدف ھذه الدراسة أن لھا حل جید من إ. للحصول على ممیزات كل منھما .وزع مستند على نموذج الشبكة الصغیر العالمي لتحسین أداء النظام بشكل فعالتعاوني م <4d6963726f736f667420576f7264202d20e3c7cccf20e6e3cde3cf20e6c7d3d1c7c131322d203139> al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 14, no. 3, september, (2018) p.p. 1219 construction and characterization of organic solar cell and study the operational properties majid h. majeed* mohamed abdul kareem** esraa h. ali *** *middle technical university/ baghdad/ iraq **,*** department of technical material engineering / middle technical university/ baghdad/ iraq *email: mtuniversity@gmail.com **email: muhamedliver19@gmail.com ***email: esraa87hussein@gmail.com (received 10 july 2017; accepted 10 january 2018) https://doi.org/10.22153/kej.2018.01.004 abstract this article reviews the construction of organic solar cell (osc) and characterized their optical and electrical properties, where indium tin oxide (ito) used as a transparent electrode, “poly (3-hexylthiophene2,5-diyl) p3ht / poly (9,9-dioctylfluorene-alt-benzothiadiazole) f8bt” as an active layer and “poly(3,4-ethylenedioxythiophene)-poly (styrene sulfonate)” pedot: pss which is referred to the hole transport layer. spin coating technique was used to prepared polymers thin film layers under ambient atmosphere to make osc. the prepared samples were characterized after annealing process at (80 ͦ c) for (30 min) under non-isolated circumference. the results show a value of filling factor (ff) of (2.888), (0.233) and (0.28) and power conversion efficiency (pce) of (0.0055), (3.333 � 10-6) and (0.0004), where these results were obtained by keithley electrometer model 6517b, while spectral response is being utilized by leoi-94 monochromator and keithley 6517b electrometer. keyword: organic solar cell, p3ht, f8bt, pedot, pss, spin coating. 1. introduction the need for an energy where its sources are un-depleted, can be manufactured and environmentally friendly with no emitting of co2. sources do not need millions of years to produce naturally like oil and coal. all these requirements and needs make organic solar cells the suitable solution where it also not causes soil toxicity if it was thrown away [1] and [2]. oscs are a recommended technology nowadays due to their flexibility and low-cost production. typically, the organic solar cell based on a blend of acceptor and donor material [3] and [4]. depending on the acceptor material there are two types of oscs; polymer/fullerene and polymer/polymer solar cell [5] where the first group refers to a blend of polymer donor with fullerene derivative acceptor such as (p3ht: pc61bm) which is intensively most studied and improved their efficiencies for about 10%. the second group is indicating a blend of polymer donor with polymer acceptor which is investigated recently where their efficiencies are about 2% or less [5] and [6]. the organic solar cell oscs is developed throughout the last ten years where this development including the synthesis of advanced material that been used, oscs structure and fabrication process which is getting simple [4]. depending on the displacement of charge carriers through the solar cell layers, the geometries of oscs can be divided into two groups: the normal and the inverted solar cell [7] and [8]. the reason that makes fullerene derivative acceptor like pcbm give higher efficiencies than majid h. majeed al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 1219 (2018) 12 polymer acceptor like f8bt is due to the excitons dissociation, electron–hole mobility and the work function between lowest unoccupied molecular orbital (lumo) donor and lumo acceptor [5]. the working principle based on four stages [4] as shown in fig.1. the following steps explain by details this mechanism: 1absorption of the incident light by the donor material through the transparent electrode (ito) [3]. 2generation of excitons at the donor. 3excitons dissociation at the (d/a) interface, where the positive and negative charges transfer to the electrodes. 4charge collection at the electrodes. fig. 1. the four stages of work principle that indicated by energy level. the last stage refers to the collecting of charge carriers where electrons and holes move toward negative and positive electrodes, respectively [3], [4], [9] and [10]. the whole process of the normal organic solar cell can be summarized by the absorption of photons through the donor material where the electrons in “the highest occupied molecular orbital homo level” excited to “the lowest unoccupied molecular orbital lumo level”, which is no longer occupied lumo level but instead of that there are “partially occupied molecular orbital pomo” [4]. the generated exciton is tending to shift toward the d-a interface. in the next stage, the electron in donor lumo level is transferred to the acceptor lumo level [10]. it must be mentioned that the working principle of the inverted organic solar cell is a little bit different due to the layers’ sequence. 2. solar cell parameters the power conversion efficiency pce is the ratio of the output power to the input power, where pce [11]. pce = �� ��� ��� � …(1) [3] the fill factor ff refers to the ratio of actual maximum power output (� ��� to the theoretical power output that represents the product of shortcircuit current and open-circuit voltage. [12] ff = ������ ������ ...(2) [3] the spectral response (s.r.) refers to the effect of the different incident light spectrum on a solar cell. if the produced current (i) in solar cell is divided by the incident light power (p), the responsivity spectrum (rλ) is produced with (a/w) unit [13] r� � � ...(3) [13] eqe or ipce refers to “incident photon to converted electron” or “internal photon to current efficiency” which represents collecting photocurrent as a response to the incident light, as shows in the equation below [14]: ���� � ��� ��� ���� � �� � ! ��� � "#$%� &� ' � ( �' � ...(4) [14] where pin is the input light irradiance (w/m2), vmp and jmp are voltage and current at the maximum power, j sc is the short circuit current density (ma/cm2) or (μa/cm2), voc; the open circuit voltage (volt) and λ is the wavelength. it is well known that every single device generating electricity has an internal series resistance. in the solar cell the internal resistance rs is a result of some reasons like the contact mode between the semiconductor and the electrode metal; the current flow direction through the emitter and solar cell as well as the resistance between two electrodes. [15] [16] isc rs = ' ) * + ln .�� + ��� '/* 0���⁄ �� 2 ...(5) where io is the reverse saturation current = 0.01μa/cm2 , n is the ideality factor ≈ 1, k is the boltzmann constant = 1.38*10-23 j/k, t is the temperature in kelvin (k) ≈300 k at room temperature and q is the charge of electron = 1.6*10-19 c. [11] majid h. majeed al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 1219 (2018) 13 3. experimental work 3.1 sample preparation ito glass with (3*3cm2) was etched from (0.5 cm) tip by hcl acid with zinc grain and cleaned by acetone for 10 min with magnetic stirrer then with (0.2%) (hellmanex iii ossila, c141) dissolved in di-water for 10 min in magnetic stirrer after that the samples were immersed inside hot di-water for 10 min with stirrer then the samples were stored in di-water at ambient temperature. on the top of cleaned ito sample, a hole transport layer of “poly (3,4-ethylene dioxythiophene)poly (styrene sulfonate) pedot: pss” (ossila, m124) was spin coated at (3000 rpm) for (60 sec), annealed at (150 ͦ c) for (10 min). the active layer was constructed from “poly (3-hexylthiophene2,5-diyl) (p3ht)” (ossila, m102) and “poly (9,9-dioctylfluorene-alt benzothiadiazole) (f8bt)” (ossila, m231) as “donor/acceptor bulk heterojunction (bhj)”, where it is prepared by dissolved in chlorobenzene and stirrer at (70 ͦ c) over 14 hours in darkroom. this blend is spin coated at (2000, 3000 & 2500 rpm), where these samples are annealed at (80 ͦ c) for (30 min). an aluminum electrode was evaporated by vacuum thermal evaporation at the etching tip. the design of sample is illustrated in fig. 2. fig. 2. fabrication sequences of normal osc device with bhj blend ito/pedot: pss/p3ht:f8bt/al. 3.2 device characterization keithley 6517b electrometer with a tungsten lamp (1200 w/m2) gives the jvcurve of each sample while the spectral response is being utilized by leoi-94 monochromator and keithley 6517b electrometer. fig.3 and fig.4 show these devices. fig. 3. keithley 6517b electrometer. fig. 4. leoi-94 monochromator. 4. results and discussion the complete device is illustrated in fig (5) exhibiting a homogeneous and uniform distribution for pedot: pss and the blend due to using static dispense method which refers to add a suitable amount of solution for whole the substrate and then rotates it. the current density–voltage (j-v) curve for the three samples illustrated in figures (6), (7) and (8). these figures show results that indicate a low voc and jsc which means low ff and pce as illustrated in table (1), (2), (3), (4) and (5) where these low electrical properties are due to the non-isolated fabrication process where sample exposed to oxygen and humidity also the electrodes are connected to copper (cu) wire by indium (in) at each tip (electrodes) this increase the series resistance rs. [15] while the optical properties were affected by the spin coater speed that effects on the thickness of thin film. the spectral response shows the effect majid h. majeed al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 1219 (2018) 14 of different wavelength on output current for osc. ipce is more elementary than responsivity which is used in theory. [17] fig. 5. normal osc picture of samples. fig. 6. jv curve of (2000 rpm) spin coater speed sample. fig. 7. jv curve of (3000 rpm) spin coater speed sample. fig. 8. jv curve of (2500 rpm) spin coater speed sample. 4.1 calculations of electrical properties by keithley electrometer results for each sample we can calculate ff, pce and rs as shown in results table (1), (2), (3) and (4)., ��� � ��� ��� � and isc rs = ' ) * + ln .�� + ��� '/* 0���⁄ �� 2 where isc =jsc �9 cm2 for pin =2100 w/m2= 0.21 w/cm2 table 1, electrical results obtained by keithly electrometer sample no. vmp jmp voc jsc sample-10.013 0.09 0.027 0.015 sample-20.0007 0.001 0.0015 0.002 sample-30.012 0.007 0.024 0.0125 table 2, fill factor results ff 345645 378698 results ff 1 0.013 � 0.09 0.027 � 0.015 2.888 ff 2 0.0007 � 0.001 0.0015 � 0.002 0.23333 ff 3 0.012 � 0.007 0.024 � 0.0125 0.28 table 3, power conversion efficiency pce 645 345 cde results pce 1 0.013 � 0.09 0.21 0.005571 pce 2 0.0062 � 0.011 0.21 3.333 � 10-6 pce 3 0.012 � 0.007 0.21 0.0004 majid h. majeed al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 1219 (2018) 15 table 4, series resistance result rs [e h i j kl .m7 j 378 eni 0m98⁄ m7 2] ÷ qsc result k ω rs1 [0.02587 ln .�%.%"�".r�"%stu�%.%#v "�w%%�".wx�"%s�y �0%."wz�"%s[⁄ %.%" 2] /0.135� 100r 199.97 rs2 [0.02587 ln .�%.%"�".r�"%stu�%.%%"z "�w%%�".wx�"%s�y �0%.%"x�"%s[⁄ %.%" 2]/ 0.018� 100r 4092.705 rs3 [0.02587 ln .�%.%"�".r�"%stu�%.%#$ "�w%%�".wx�"%s�y �0%.""#z�"%s[⁄ %.%" 2]/ 0.1125� 100r 17.256 table 5, compering between fill factor ff, power conversion efficiency pce and series resistance rs results sample number spin coater speed (rpm) keithley electrometer ff pce rs (kω) 1 2000 2.888 0.0055 200 2 3000 0.233 3.333 � 10-6 4093 3 2500 0.28 0.0004 17.26 the power conversion efficiency pce and fill factor ff can be affected by the series resistance, where rs is due to the internal resistance of the oscs at the electrode especially at the indium with copper wire and at the measurement device such as keithley electrometer. 4.2 calculations of optical properties while spectral response shows the effect of different wavelength on output current for organic solar cell osc, the eqe illustrates the efficiency of osc at different wavelengths. quantum efficiency eqe is more elementary than responsivity which is used in theory. keithley electrometer model 6517b with the grating monochromator give the optical properties of the organic solar cell. r� � � ipce � eqe � jcd �ef dg�� � phi� μw cm#�� � 1240� ev nm� λ �nm� for example, at wavelength of (500 nm). r�1 = %.%%%#z #.x%q = 8.899� 100z ma/w ���� � �r� � %.%#vvv ��� ���� � w"#""".""� � ! ��s � "#$%� &� ' � z%% �' � eqe1= 2.2 � 100v r�2 = %.%%%vvz #.x%q = 2.758� 100$ ma/w ���� � �r� � %.%xr"" ��� ���� � w"#""".""� � ! ��s � "#$%� &� ' � z%% �' � eqe2= 6.8422� 100v r�3 = %.%%%#wx #.x%q = 8.472� 100z ma/w ���� � �r� � %.%xr"" ��� ���� � w"#""".""� � ! ��s � "#$%� &� ' � z%% �' � eqe3= 2.1� 100v figure (9) indicates the effect of different spectrums on (2000 rpm) spin coated sample osc. in which the cell shows increased response from (400 nm) until reaching (500 nm), then a slight and gradual decrease in responsivity at (600 nm) followed by a slight increase at (700 nm) then a sharp decreased. this plot shows the proper band width is about (500-700 nm). figure (10) shows that at (500 nm), the maximum eqe was (0.000022%), while this diagram gives information about the collected electron per incident light flux, it also shows a slight decrease in quantum efficiency. this decrease means that the incident light effect or (pin effect) is very small on the quantum efficiency of this cell. figure (11) indicates the effect of incident light on (3000 rpm) spin coated sample where the highest responses at (500 nm) followed by a slight decrease then a little increase at (750 nm), where the bandwidth is about (500-750 nm). figure (12) shows that at (500 nm), the maximum eqe was (0.000068%). this ipce was larger than that of sample-1, this can explain by the effect of the fabrication process of this sample, where the spin coater speed was (3000 rpm) this can decrease the thickness of active layer which effect on the efficiency of (electron/hole) pair generated and efficiency of interfacial charge transfer which effected on ipce. figure (13) illustrated the spectral response of (2500 rpm) spin coated sample that shows a sensible response from (500-750 nm), where the highest response at (500 nm) followed by a slight decrease at (650 nm) then a little rise at (750 nm). figure (14) shows that at (500 nm), the maximum eqe was (0.000021%), where the spin coater majid h. majeed al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 1219 (2018) 16 speed was (2500 rpm) this can decrease the thickness of active layer which increases the quantum efficiency but the recombination of the charge carrier at the interface after examined for a while cause drop in ipce. fig. 9. spectral response of (2000 rpm) spin coated sample. fig. 10. quantum efficiency of (2000 rpm) spin coated sample. fig.11. spectral response of (3000 rpm) spin coated sample. fig. 12. quantum efficiency of (3000 rpm) spin coated sample fig.13. spectral response of (2500 rpm) spin coated sample fig. 14. quantum efficiency of (2500 rpm) spin coated sample majid h. majeed al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 1219 (2018) 17 5. conclusions the (2000 rpm) spin coated sample show stable electrical and optical properties while this sample is fabricated at (2000 rpm) which can be represented as the suitable speed for fabrication this type of organic solar cell. the power conversion efficiency pce and fill factor ff can be affected by the series resistance, where rs is due to the internal resistance of the oscs at the electrode especially at the indium with copper (cu) wire. the optical properties such as responsivity rλ and ipce is affected by the fabrication process by manipulating the thickness of active layer where it decreases with increasing speed of spin coater that effect on the donor/acceptor interface which effect on the exciton generation and collection. the results show the poor electrical properties of p3ht: f8bt blend due to the low work function where the p3ht lumo/ f8bt lumo offset is (~ 0.3 ev) and the suitable value generally is (0.5 ev). higher optical and electrical response can be obtained by reducing the annealing temperature up to (80 ͦ c) for a longer time (30 min), this is due to the fabrication process is done at ambient condition without gloves-box. using a static dispensation method can increase the homogeneity of spin-coated polymer layers and make a uniform thin film. the prepared samples from pedot: pss dispersion is suitable to use dispersion without filtering or stirrer. acknowledgement i would like to express my sincere gratitude and appreciation to my advisor prof. dr. majid h. majeed for his advice throughout the period of this research. true deep thanks and appreciation to dr. mohamed abdul kareem (رحمه هللا) for his patience, motivation, enthusiasm, and knowledge. his guidance helped me in all the time of research and writing of this thesis. i could not have imagined having a better advisor and mentor for my thesis. i would like to thank all the people who have given help and i have not mentioned them. 6. references [1] horigome, t., kimura, k., takakura, t., nishino, t., & fujii, i.; “clean and safe energy forever”, i ed., vol. 1, international solar energy society proceedings series, newnes, 2012, p 20. [2] zang, l.; “energy efficiency and renewable energy through nanotechnology”, green energy and technology. london: springer science & business media. 2011, p 171. [3] kim, m. s.; “understanding organic photovoltaic cells: electrode, nanostructure, reliability, and performance”, dissertation on the degree "doctor of material science and engineering”, university of michigan, (2009), pp8-25. [4] renee kroon, martijn lenes, jan c. hummelen, paul w. m. blom, and bert de boer; “small bandgap polymers for organic solar cells (polymer material development in the last 5 years)”, university of groningen, groningen, the netherlands, taylor & francis group, 2008, pp 531540. [5] łukasz bernacki , zbigniew lisik , beata łuszczyńska, “the evaluation of organic solar cell’s properties based on polymer f8bt and fullerene derivative c60pcbm”, przegląd elektrotechniczny, r. 91 nr 9, 2015, p 13. [6] seth marder & kwang-sup lee, photoresponsive polymers ii, vol. 2014, advances in polymer scienc, springer, 2008, pp. 4-5. [7] wallace c.h. choy; “organic solar cells: materials and device physics, department of electrical and electronic engineering”, university of hong kong, china, green energy and technology, springer science & business media, 2012, pp 160-161. [8] barry p. rand, henning richter; “organic solar cells: fundamentals, devices, and upscaling”, taylor & francis group, crc press, 2014, chapter -15, pp (713-725-727-730221). [9] rieger, r.; “extended donor and acceptor molecules for organic electronics”, dissertation on the degree "doctor of science", the department of chemistry, pharmacy and geosciences johannes gutenberg university mainz, 2009, p 11. [10] barry c. thompson, jean m. j. fréchet; “polymer–fullerene composite solar cells”, volume 47, issue 1, angewandte chemie international edition, 2007, p 60. [11] qing zhang, w. i. milne; “advances in nanodevices and nanofabrication: selected publications from symposium of nanodevices and nanofabrication in icmat2011”, taylor & francis group, crc press, 2012, p 103. [12] jha, a. r.; “solar cell technology and applications”, crc press, 2009 p 94. majid h. majeed al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 1219 (2018) 18 [13] stuart r. wenham, martin a. green, muriel e. watt, richard corkish, alistair sproul; “applied photovoltaics”, 3rd ed, routledge, 2011, p 45. [14] bo wu, nripan mathews, tze-chien sum; “plasmonic organic solar cells: charge generation and recombination”, springerbriefs in applied sciences and technology, nanoscience and nanotechnology, springer, 2016, pp (7-3940). [15] k.l. chopra, s.r. das ; “thin film solar cells”, 1st ed., springer science & business media, 1983, pp 130-131. [16] ramchandra pode, boucar diout; “solar lighting”, springer science & business media, 2011, p 32. [17] ronald g. driggers; “encyclopedia of optical engineering: pho-z, marcel dekker”, dekker encyclopedias series, vol.3, encyclopedia of optical engineering, crc press, 2003, p 2200. )2018( 12-19، صفحة 2د، العد14دجلة الخوارزمي الهندسية المجلم ماجد حميد مجيد 19 ـف الخاليا العضوية ودراسة خصائص التشغـيـلاء وتوصيبن إسراء حسين علي*** محمد عبد الكريم إحمد** د*د مجيـماجد حميـ بغداد / العراق /نية الوسطىالجامعة التق* العراق /الجامعة التقنية الوسطى/ بغداد /قسم هندسة تقنيات المواد** ،*** mtuniversity@gmail.com:البريد االلكتروني* muhamedliver19@gmail.com :البريد االلكتروني** esraa87hussein@gmail.com:البريد االلكتروني*** الخالصة ودراسة العادية العضوية . هذا البحث يتضمن تصنيع الخاليا الشمسيةاالخيرة بشكل واسع ) في اآلونةoscsأستعملت الخاليا الشمسية العضوية ( وتأثير مختلف االطوال الموجية على ذلك النوع من الخاليا. )ff) ومعامل التعبئة (pceخصائصها الكهربائية والضوئية مثل كفاءة تحويل الطاقة ( -٢،٥-هيكسيلثيوفين-٣) وطبقة فعالة من المانح والمستقبل مكونة من بولي (ito–قصدير االنديوم (زجاجة من أوكسيد اشفاف اتتضمن الخلية الشمسية قطب (ستيرين سلفونات) -إثيلينيدوكسيثيوفين) بولي-٣،٤طبقة من بولي ( فضال عن) f8btبنزوثياديازول (-ألت-ديوكتيل فلورين-٩،٩) و بولي (p3htدييل) ( )pedot: pss بقة ناقلة للشحنات الموجبة.) الذي يستعمل ط إلكتروميتر لقياس طة سابوتم الفحص ) لتحسين أداء السطح البيني للمانح والمستقبل. bhjتم إستعمال تقنية الطالء بالغزل الدوراني حيث استخدم مزيج ( مخطط االستجابة فضال عنعلى مخطط التيار والفولتية ومطياف االستجابة الطيفية ألجل الحصول b)٦٥١٧ keithley-التوصيلية الكهربية للتيار المستمر الطيفية. على (0.28) و (0.233) و (2.888)كانت نتائج العينات الثالثة (االولى والثانية والثالثة ) للخاليا العادية: بالنسبة لمعامل التعبئة كانت نتائج العينات هي على التوالي، مأخوذة من مخطط التيار والفولتية، )0.0004(و )3.333 � 10-6 (و )0.0055(التوالي وبالنسبة لكفاءة تحويل الطاقة كانت نتائج العينات وهي تمثل الخواص الكهربائية حيث لوحظ تأثير المقاومة المتسلسلة على كفاءة الخلية. ي االستجابة الطيفية للخاليا اللشمسية فكان لتغيير سرع الدوران لجهاز الطالء بالغزل الدوراني تأثيير في كفأءة الكم الخارجية بينما لوحظ تأثير عملية التصنيع ف )eqe و ٣٠٠٠) و (٢٠٠٠لعينات تم طالء الطبقة الفعالة منها بسرع ((%0.000021) و (%0.000068) و (%0.000022)) والتي اعطت نتائج ( )٢٥٠٠ (rpm التوالي. على al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 111 (2013) drilling of fr-4 composite materials using single pulse of nd:yag laser osamah f. abdulateef* enas a. khalid** amer g. hoss*** *,**,***department of automated manufacturing engineering/ al-khwarizmi college of engineering/ university of baghdad *email: drosamah@kecbu.uobaghdad.edu.iq **email: enaslaser77@yahoo.com ***email: amer_gazee@yahoo.com (received 9 april 2012; accepted 24 march 2013) abstract laser drilling is capable of producing small, precisely positioned holes with high degree of reproductively. in this paper , ir millisecond nd:yag single pulsed laser was used to determine the effect of laser parameters on the drilled hole of the glass fiber reinforced epoxy composite fr-4 sample of 2 mm in thickness . the type of laser source was gsi lumonics jk760tr series laser 1.064μm system in a cnc cabin. the jk760tr series has a 0.350ms pulse length and a maximum repetition rate 500hz with an average power of 600w. the investigation of single pulse laser drilling in this paper was based on theoretical and experimental solutions. in single pulse technique, the investigation included focal plane position fpp, pulse shape, laser peak power, and pulse duration. it was found that (-1) was the best fpp due to less taper for the drilled holes made by this level (entrance hole =0.68, exit hole = 0.27). to predict pulse shape effects; three types were : rectangular , rump-up and cool down, it were examined found that rectangular pulse was efficient more than the other types due to its ability to produce holes with less tapering as compared with others types. also its found that all pulse shapes had the same effect on the materials microstructure . laser peak power and pulse duration had the predominant affects on the hole dimensions and edge quality without any defect except hole tapering. keywords: nd:yag laser, fr-4 composite materials, laser drilling. 1. introduction fr-4 composite material is a fiber reinforced epoxy resin made from an epoxy resin matrix reinforced by fine glass. they have attracted a significant amount of attention from both industry and academia. the excellent tensile strength of glass fibers, however, may deteriorate when loads are applied for long periods of time. laser hole drilling in composite materials has been applied widely in industry and became an essential tool for micro-drilling in many components used in the technologically advanced industries. basic material removal mechanism in laser drilling is based on the absorption of laser energy from a series of laser pulses at the same spot. as a result of which, material gets melted and ejected to form a hole [1, 2]. laser micro-drilling does not need expensive cutting tools and does not produce mechanical forces that can damage delicate work pieces. the use of laser micro-drilling or micromachining in manufacturing industry can be attributed to its flexibility and ability to process variable quantities and qualities of materials in a very short time with very high surface finish, accuracy, and minimum amount of wastage. laser machining could drill a hole in very small diameter size, but it will require well controlled laser parameters in order to produce a high quality of hole. defects that could occur due to inappropriate parameters setting are like overheating, fiber swelling, large heat affected zone haz and air plasma spraying aps. most of the defects are caused mailto:drosamah@kecbu.uobaghdad.edu.iq http://en.wikipedia.org/wiki/fiber_reinforced_plastic http://en.wikipedia.org/wiki/fiber_reinforced_plastic osamah f. abdulateef al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 111(2013) 2 by the rapid heating of the laser beam. the material removal rate mrr for laser machining is not limited by constraints such as maximum tool force, built-up edge formation, or tool chatter. however, due to the presence of thermal effects, the spatial resolution available from conventional, wider pulse lasers operating at visible and infrared wavelengths of the spectrum is limited. since the absorption coefficient of different materials is highly wavelength dependent, by selecting the laser beam wavelength from deep ultra-violet (uv) to infrared (ir), one can precisely control the material processing [3]. many researches deal with the micro drilling of composite materials. m.m.noor, t.t.mon, k.kadirgama, 2009 , [4] , nontraditional machining method was employed by using co2 laser to drill the fiber-glass composite sheet of 2 mm in thickness having four layers of glass-fiber with orientation <0, 90, 0, 90>. the machining parameters under consideration were laser power and pulse duration. hole quality were then compared for each parameter combination. it was found that the laser power had predominantly affected the quality of the hole in fibre-glass composite material during laser-drilling. a. demir, l. candan, t. canel, v. gunay, and t. sınmazcelik, 2009[5], predicted and evaluated the effect of pulse duration and peak power of nd:yag laser to find optimum laser parameter in the drilling operation. the average hole diameters and the average taper angles are examined as a function of the laser pulse duration and the laser peak power. the experimental results indicated the diameters of the craters show approximately linear proportion with the pulse duration and the peak power. avanish, k. d. & vinod y., 2007, [6], predicted and evaluated the effect of laser parameter in the drilling of composite material using nd:yag laser. this study concluded that haz was directly proportional to laser power, where an increase in power would result in an increase in haz and it works in the opposite for the cutting speed. w.s.o. rodden, s.s. kudesia, d.p. hand, j.d.c. jones, 2002, [7], the results of an extensive experimental study of the free running nd:yag laser drilling of a multi-layer carbon fiber composite, where adjacent layers had differently orientated fibers. for holes drilled with the laser operating in fixed-q mode at 1064 nm, parallel sections of blind holes illustrated discontinuities in the hole size along a given section direction detailed single pulse drilling characteristics presented illustrating the exit hole diameter as a function of pulse energy and material thickness. zheng hongyu , eric gan kok wah 2000 [3], presented the experimental investigation of drilling fr4 , polyimide and alumina substrates using the rf and tea co2, 3rd-harmonic nd: yag, and krf excimer lasers, respectively. both blind and throughvias were drilled and evaluated for taper, wallangle and smoothness through optical microscope, sem and cross sectional analyses. in this paper we identifying the most significant parameters governing the quality of the holes in fr-4 composite materials drilled by millisecond nd:yag laser by varying the laser parameters pulse peak power, pulse energy , pulse duration, focal plane position(fpp) , and pulse shape to produces a high quality hole with minimal residue and consistent edge quality from entry to exit point. and studying the effects of varying laser beam parameters on the hole dimensions (diameter and depth) and hole quality. 2. one-dimensional model for laser drilling drilling can be divided into two stages: heating and material removal, as shown in figure1. in the heating stage, the temperature of the work piece surface, ts, is increased up to the phase transition temperature, tm, by the laser beam. the heating stage is usually very short because the laser beam intensity is very high. in the material removal stage, the hole depth is increased through molten material removal. heating stage drilling stage fig. 1. heating and material removal stages of laser drilling [9]. osamah f. abdulateef al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 111(2013) 3 during the heating stage, the work piece surface is not thermally eroded. it is difficult to obtain a simple analytical solution for drilling as a non steady process with three-dimensional heat transfer characteristics. thus, it is assumed that drilling is a one dimensional process and that the laser beam intensity is uniform. the boundary conditions are: at z = 0 → i= κ (dt/dz)z=0 …(1) and at z → ∞, t=t0 where i0 is the laser beam intensity(w/m 2 ), and t0 is the initial temperature( o k). the temperature distribution inside the workpiece can be derived, to be [8] t-t0 = 2𝐼0 𝐾 𝐾𝑡 𝜋 1 2 𝑒 −𝑍2 4𝑘𝑡 − 𝐼0𝑧 𝑘 …(2) where κ is the thermal diffusivity (cm -2 s -1 ) and i0 is the laser beam intensity. the temperature distribution given by eq. 2 is valid under the condition that (κt) 1/2 <ω [8], which can be achieved either through low diffusivities or short drilling times. the time for the workpiece surface to reach the solid-liquid phase transition temperature tm can be determined from eq.2. applying ts = t at z = 0, the following relation can be obtained [8] t – t0 = 2𝐼0 𝑘 𝑘𝑡 𝜋 1 2 …(3) the duration of the heating stage, th in second, can be calculated as [8] th= 𝜋 𝑘 𝑘 𝑇𝑚−𝑇0 2𝐼0 2 …(4) where tm is a melting temperature( o k). during the heating stage, a hole is not made because phase transition does not occur. after the surface temperature reaches the melting point, drilling starts. in order to determine the hole depth as a function of time and process variables, a one-dimensional analysis is considered, figure 2 a laser beam is assumed to have a uniform intensity distribution i0 defined as [8] i0 = 𝑃 𝜋𝑤2 …(5) where p is the laser power (n/m 2 ) and w is laser beam radius at the surface of a workpiece (mm). fig. 2. one-dimensional drilling [8]. 3. experimental work in this paper, fr-4 sheet of 2 mm in thickness was drilled by using millisecond pulsed nd:yag laser. the schematic diagram of the experimental setup is shown in figure 3 .machining is done on the fr-4 composite material samples by changing the laser parameters. the type of laser source was gsi lumonics jk760tr series laser (class 4) (ir) wavelength 1.064λ system in a cnc cabin sees figure.4. it has a 0.3-50ms pulse length and a maximum repetition rate 500hz with an average power of 600w.laser output power is delivered via a 600 μm radius fiber optic cable to the focus head at the work station for processing. the laser beam was focused on to the fr-4 sheet using 160mm focal length plano convex lens investigate the drilling process of composite materials . glass fiber/epoxy composites sheet type 2116 fr-4 having twelve layers of glass-fiber with orientation <0, 90 respectively > .single pulse laser drilling method was used. crater investigations such as crater diameter, depth were performed at five laser peak powers, six pulse duration, four fpp, and three pulse shapes. the laser beam mode is tem 00 . the spot size of the laser beam on the composite materials substrate is 480 μm. the applied parameters in the experiments are given in table 1. osamah f. abdulateef al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 1-11 (2013) 4 table 1, laser parameter in single pulse technique applied during experimental. wave length 1.064μm nd:yag pulsed laser peak power pulse duration pulse energy pulse shape fpp from 3kw to 9kw with 1.5 kw increment from 1ms to 4ms with 1ms increment from 3j to 36j rup-up cool down rectangular from +1 to -2 mm with 1 mm steps fig. 3. experimental setup for nd-yag jk760tr. osamah f. abdulateef al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 1-11 (2013) 5 fig. 4. millisecond pulsed nd:yag laser head. the minimum spot size is calculated as follows [8]: 𝐬𝐩𝐨𝐭 𝐬𝐢𝐳𝐞 = 𝐥𝐞𝐧𝐬𝐞 𝐟𝐨𝐜𝐚𝐥 𝐥𝐞𝐧𝐠𝐭𝐡 𝐜𝐨𝐥𝐥𝐢𝐦𝐚𝐭𝐨𝐫 𝐨𝐩𝐭𝐢𝐜𝐬 𝐟𝐨𝐜𝐚𝐥 𝐥𝐞𝐧𝐠𝐭𝐡 + 𝐛𝐞𝐚𝐦 𝐞𝐱𝐩𝐚𝐧𝐬𝐢𝐨𝐧 𝐟𝐚𝐜𝐭𝐨𝐫 ∗ 𝐟𝐢𝐛𝐞𝐫 𝐝𝐢𝐚𝐦𝐞𝐭𝐞𝐫 = (160 mm /200mm)*600µm = 480μm …(6) the glass fiber used in this paper is made from an epoxy glass laminate, which employs a resin based on bt/epoxy with 12-layer woven fabrics of glass fiber and epoxy resin that has orientation (90 o , 0 o ) “e-glass” reinforcement (see figure 5). the relatively low dielectric constant and low manufacturing cost of the glass-epoxy system make it ideal for many printed circuit applications. 52-56% silicon oxide, 12-16% aluminum oxide and 16-25% calcium oxide [2].the elemental analysis of the selected materials at the specific point was tested by using energy-dispersive x-ray spectroscopy connected to a scanning electron microscopy (sem) .the mechanical and physical properties of the fr-4 are listed in table.2. the experimental procedures are as follows: 1. fixing the workpiece and identifying the lines of drilling. 2. drilling the workpiece. 3. cutting and coating the workpiece. 4. 4. taking images by the scanning electron microscopy (sem) and optical microscope for analysis purpose. osamah f. abdulateef al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 1-11 (2013) 6 fig. 5. a: 2116 glass fiber composite fr-4 work piece: b: high magnification (16x) showing glass fiber. table 2, mechanical and physical properties of the fr-4 [11]. tensile strength mpa 1,770 rockwell hardness 110 m scale temperature limit ( o c) up to 120 glass melting temperature ( o c) resin above 1590 not applicable density (g/cm 3 ) 1.85 specific heat (j/kg 0 k) 960 heat capacity(j/m3-k) 1.703*10 -6 thermal conductivity (w/m-°c) 0.16 – 0.20 permittivity-a 4.8 thermal expansion coefficient 10 -6 1/ 0 k 0.9 1.5 x 10 -5 4. results and discussion laser macro drilling on the fr-4 sheets are presented and discussed for the study of the effect of laser parameters on micro drilling results. there are a total of 24 holes in the final actual experiment based on the parameter range under consideration. prior to this, trial holes were drilled in order to acquire minimum amount of laser power, pulse duration, and pulse shape that can penetrate the composite specimen of 2mm thickness and to see the effects on the materials microstructure. to determine the effects of the laser parameters; starting reference parameters were first been determined as; 2 ms pulse width, 3 kw peak power, 10 hz repetition rate, and -1 focal position. all experiments were applied at 160 mm focal length. these parameters have were changed systematically to investigate these effects on macro drilling results. the holes were drilled by unique pulse, first fpp was changed to obtain the optimum surface level for drilling operation, and then the laser parameters (peak power, pulse duration) were changed to obtain ties effects on macro drilling results. http://en.wikipedia.org/wiki/permittivity osamah f. abdulateef al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 1-11 (2013) 7 4.1. effect of focal plane position (fpp) in laser processing, intensity (power per unit area) of the laser beam at the material surface is of prime importance. intensity is great enough to melt or vaporize any material generated by focusing a laser beam. the maximum irradiance is obtained at the focal point of a lens, where the beam is at its smallest diameter. intensity values of billion of watts per square centimeter can be obtained at the focal spot. during this experiment the fpp is considered zero on the workpiece surface and above or below the surface is considered positive or negative, respectively. the fpp was changed from +1 to -2 in a single drilling. as shown in figure 6 the hole not drilled at +1 fpp and the entrance diameter of the hole was maximum value 0.955, so +1 fpp is already eliminated, but it did not change much at -1 and 2 mm focal plane positions when compared to the other positions. circularity of the hole for -1mm focal position was better than the one with -2 mm. it is possible to say that -1 mm focal position was a more suitable position for single drilling due to minimum entrance hole and maximum exit hole (less tapering). fig. 6. (1) effect of fpp on the dimensions of laser drilled microholes (f = 10 hz), (2) optical picture showing changing crater dimensions for different fpp. 4.2. heating stage when a laser pulse interacts with a solid target, the electrons are heated to a high temperature by the absorption of laser energy. by the electronphoton interactions, the hot electrons transfer energy to the lattice on a few picoseconds time scale for most materials [9–10]. the equilibrium between these two energies depends on the laser pulse duration. the energies transformation occur in the stage before hole beginning to drill by very short time and this stage is called heating time . the theoretical calculation for heating time that was gathered according to equation (4) showed high reduction in heating time with increase in laser peak power (see fig.7). a significant decrease in the heating time as peak power was increased from 3kw to 6kw, and the heating time is decreased slightly from 6kw to 9kw, the heating time relationship is inversive with laser power. this 0.96 0.75 0.68 0.88 0 0.245 0.27 0.25 0 0.2 0.4 0.6 0.8 1 1.2 1 2 3 4 h o le d im e n ti o n m m focal plan position entrance diameter single exit diameter single1 2 +1 0 -1 -2 osamah f. abdulateef al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 1-11 (2013) 8 decrease continues until it reaches to the lowest value before drilling process starts as shown in the values from 3-6(kw), after 6kw and due to high power transfer to the surface, the time is very close to the minimum value for start of the drilling process. so any increase in laser power even if a sudden it will be accompanied by a small decrease in the heating time. another observation is that heating time was increased as pulse width increased as shawn in figure 2. fig. 7. effect of laser power on the heating stage. 4.3. effect of laser parameters after predicting the best fpp for single pulse methods (-1) , hole dimensions were examined under different laser parameters and the results show that crater diameter was influenced strongly by changing laser parameter as shown in figure 8. it was found that laser power is the predominant effect on the hole size, burn mark and edge quality. at 1ms pulse width the laser didn’t reach to the back side of the fr-4 sample even at high peak power of 9 kw due to less interaction time between the material and the workpiece. for other pulse widths from 3kw to 6 kw the crater dimension was increased slightly and from 6 kw to 9kw the crater dimension was increased significantly. the holes made by a single pulse drilling had more tapering (see fig.9). fig. 8. effect of laser (peak power, pulse duration) on the dimensions of laser drilled micro holes in fr-4, ( f = 10 hz , and fpp = -1). 0.00e+00 1.00e-02 2.00e-02 3.00e-02 4.00e-02 5.00e-02 6.00e-02 7.00e-02 1 2 3 4 5 h e at in g ti m e μ s peak power kw 2ms 3ms 4ms 1ms 3 4 . 5 6 7 . 5 9 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 1 2 3 4 5 h o le d im e n ti o n peak power kw 2 msentrance 3msentrance 4msentrance 1msentrance 4msexit 3msexit 2msexit 3 4 . 5 6 7 . 5 9 osamah f. abdulateef al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 1-11 (2013) 9 fig. 9. aoptical images of the cross-section of fr-4 drilled hole at 2 ms pulse width. beffect of peak power at 2ms pulse width on the hole dimension. 5. conclusions the effect of the four variables on micro-hole drilling in the ir millisecond nd:yag laser ablation regimes were investigated theoretically and experimentally in single method. changes in the pulse length, pulse peak power, and pulse shape were correlated for holes depths and diameters on fr-4 composite materials. the results show: 1(-1) fpp was the best level to accomplish drilling operation, due to less tapering produced. 2heating time increases as pulse width increases while its decrease as peak power increase. 3in all cases of this experimental work, high laser power density affects the hole in two ways; depth and width, it also increase melt. this implies imparting energy quicker and maintaining higher temperatures within the hole makes the process more efficient. 4increased ablation times have two effects on hole creation, first, the removal rate is increased, and second, the hole quality experiences degradation. for holes requiring high removal rates yet not as perfect hole quality, longer pulses become ideal. 6. acknowledgment we would like to thank the staff of kocaeli university, laser technologies research and application center,turkey , specially prof. dr arif demir , dr. e. kacar, erhan akman, and b. genc oztoprak for inviting us and giving us this opportunity to use laser devices and different materials in laser technologies laboratory / kocaeli university to complete our experiment work. 7. references [1] william t. silfvast , university of central florida , orlando, florida, the national science foundation , fundamentals of photonics ,1995 ; grant # due 9752029 [2] emre teoman, dana lee church, general laser micro machining principles, oxford press, great britain ,1985. [3] zheng hongyu, eric gan kok wah, investigation of laser micro-drilling of pcb substrates, advanced machining group, process technology division, 2000. [4] m.m.noor, t.t.mon, k.kadirgama, m.r.m.rejab, drilling on fibre-glass composite using co2 laser, faculty of mechanical engineering, university of malaysia pahang (2009). [5] e. kacar, m. mutlu, e. akman, a. demir, l. candan, t. canel, v. gunay, t. sınmazcelik, a b 0.5 mm. osamah f. abdulateef al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 1-11 (2013) 10 characterization of the drilling alumina ceramic using nd:yag pulsed laser university of kocaeli, laser technologies research and application centre, 41380 umuttepe, kocaeli, turkey(2009). [6] avanish, k. d. & vinod, y.,“laser beam machining – a review”. international journal of machine tools & manufacture, vol. 48, pp 609 628 (2007). [7] w.s.o. rodden*, s.s. kudesia, d.p. hand, j.d.c. jones , a comprehensive study of the long pulse nd:yag laser drilling of multilayer carbon fiber composites, department of physics, heriot-watt university, edinburgh eh14 4as, uk, optics communications 210, 319–328(2002). [8] h. s. carslaw and j. c. jaegar, conduction of heat in solids, oxford press, great britain (1975). [9] w. han, j. s. yokum, and r. j. pryputniewicz, "parametric study of laser micro-drilling process for mems fabrication”, (2004). [10] b. martin, a. loredo, m. pilloz, and d. grevey, “characterization of cw nd:yag laser keyhole dynamics,” optics and laser technology, 33:201-207(2001). [11] nayyar, piping handbook, 6th edition except for frp-glass which is based on sio2 from handbook of chemistry and physics. (2013) 111، صفحت 2، العذد9هجلت الخوارزهي الهنذسيت الوجلذ اساهت فاضل عبذ اللطيف 11 ياك –باستخذام النبضت الوفردة لليسر النيذهيوم ( فايبر كالش)تثقيب الوادة الوركبت *** عاهر غازي هوش ** يناش عبذ الكرين خالذا * اساهت فاضل عبذ اللطيف جاٍؼح تغذاد / ميٞح اىْٖذسح اىخ٘اسصٍٜ/ قسٌ ْٕذسح اىرصْٞغ اىَؤذَد***،**،* drosamah@kecbu.uobaghdad.edu.iq : االىنرشّٜٗ اىثشٝذ * enaslaser_77@yahoo.com : اىثشٝذ االىنرشّٜٗ ** amer_gazee@yahoo.com : االىنرشّٜٗ اىثشٝذ*** الخالصـــــــت ٝاك اىْثضٜ تاىَيٜ شاّٞح ىذساسح ذغٞش -فٜ ٕزا اىثحس اسرخذً ىٞضس اىْٞذًٍٞ٘. ػَيٞح اىرصقٞة تاىيٞضس ىٖا اىقذسج ػيٚ إّراض شق٘ب صغٞشج، ػاىٞح اىذقح ّذ ذصقٞثٖا تاسرخذاً ذقْٞح اىْثضح ٍيَٞرش ع 2تسَل ( اىَادج األساط ٗاألىٞاف ) خصائص اىيٞضس ػيٚ أتؼاد اىصق٘ب ٗػيٚ اىثْٞح اىَجٖشٝح ىؼْٞاخ اىَادج اىَشمثح ٗاط ٗأػيٚ ٍسر٘ٙ ذشدد ٝصو اىٚ 600ٍيٜ شاّٞح تَؼذه قذسج 50-0.3تط٘ه ٍ٘جٜ gsi lumonics jk760trّ٘ع اىيٞضس اىَسرخذً ماُ . اىَفشدج ىْثضح، ٗقذسج اىْثضح، ٗط٘ه اىْثضح ٗىقذ ٗشنو ا،فٜ حاىح اىْثضح اىَفشدج فاُ خصائص اىيٞضس اىرٜ ذٌ ذغٞٞشٕا ٕٜ ٍ٘قغ اىَسر٘ٙ اىثؤسٛ. ٕٞشذض 500 ٗرىل ( 2-، 1-، 0، 1)+ٍِ تِٞ استغ ٍسر٘ٝاخ ذٌ اسرخذاٍٖا ٕٜٗ تاىرسيسو ( 1)-ٗجذ أّ فٜ حاىح اىرصقٞة تاىْثضح اىَفشدج فاُ افضو ٍسر٘ٙ ىيرصقٞة ٕ٘ الخرثاس ذأشٞش . 0.27= اٍا فٜ ّقطح اىخشٗض فناُ 0.86= اىذخ٘ه الػطائٔ شق٘ب اقو اسرذقاقا ٍقاسّح تاىَسر٘ٝاخ االخشٙ حٞس ماُ قطش اىصقة فٜ ٍْطقح ّح تاألشناه األخشٙ شنو اىْثضح، فقذ اسرخذٍد شالز اشناه ٗذٌ ٍالحظح أُ اىْثضح اىَسرطٞيح أمصش مفاءج ٗرىل ىقاتيٞرٖا ػيٚ إّراض شق٘ب اقو اسرذقاقا ٍقاس إُ طاقح اىيٞضس ٍٗذج اىْثضح ىٖا اىرأشٞش اىسائذ ػيٚ أتؼاد ٗحجٌ اىصق٘ب ٗمزىل ػيٚ اىَْطقح اىَرأششج . اٍا ذأشٞشٕا ػيٚ اىثْٞح اىَجٖشٝح ىيَادج فناُ ٍرشاتٖا . تاىحشاسج تذُٗ أٛ ػٞ٘ب ٍاػذا اسرذقاق اىصقة اىزٛ ماُ صفح ٍالصٍح ىنو اىصق٘ب اىرٜ أجشٝد تٖزٓ اىطشٝقح mailto:drosamah@kecbu.uobaghdad.edu.iqالبريد mailto:drosamah@kecbu.uobaghdad.edu.iqالبريد mailto:amer_gazee@yahoo.com***البريد mailto:amer_gazee@yahoo.com***البريد علي طالب وعماد وقاسم al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 9, no. 1, p.p. 29-38 (2013) aircraft lateral-directional stability in critical cases via lyapunov exponent criterion emad n.abdulwahab* qasim a.atiyah** ali talib abd alzahra*** *,**,***department of machines and equipment/ university of technology *email: emadaabd@yahoo.com **email: dr_qasim_uot@yahoo.com ***email: alitalib84@gmail.com (received 13 december 2011; accepted 20 december 2012) abstract based on lyapunov exponent criterion, the aircraft lateral-directional stability during critical flight cases is presented. a periodic motion or limit cycle oscillation isdisplayed. a candidate mechanism for the wing rock limit cycle is the inertia coupling between an unstable lateral-directional (dutch roll) mode with stable longitudinal (short period) mode. the coupling mechanism is provided by the nonlinear interaction of motion related terms in the complete set equations of motion. to analyze the state variables of the system, the complete set of nonlinear equations of motion at different high angles of attack are solved. a novel analysis including the variation of roll angle as a function of angle of attack is proposed. furthermore the variation of lyapunov exponent parameter as function of time is introduced. the numerical result indicated that the system became lightly damped at high angle of attack with increasing the amplitude of aircraft state variables limit cycle. a good agreement between the numerical result and published work is obtained for the onset of limit cycle oscillation, almost at( = 20° − 23°). keywords: wing rock; nonlinear dynamic system; limit cycle oscillation. 1. introduction the wing rock phenomenon is a self-sustained oscillatory mode, typical of several modern high performance aircraft which exhibit constant amplitude rolling oscillations at moderate and high angle of attack. such dynamic systems typically possess a limit cycle which becomes stable after a buildup phase. these oscillations are sustained around a state at which the energy generation at lower amplitudes and the dissipation at larger amplitudes are balanced [1]. while maneuvering at angle of attack, many high performance aircraft can experience a self-induced limit cycle roll oscillation called a wing rock. this unwanted motion may result in limitations being placed on the aircraft's flight envelop [2]. the wing rock may diminish the flight effectiveness or even present a serious danger due to potential instability of aircraft [3]. the wing rock is undesirable because the oscillatory motion has an adverse effect on maneuverability and reduces the tracking accuracy [4]. from dynamics view, aerodynamic stability derivatives show that the wing rock is related to instability in dutch roll mode of motion of aircraft [4]. studies of the candidate wing rock mechanism showed that the unstable lateral-directional (dutch roll) mode, when inertial coupled with a stable longitudinal (short period) mode, can establish a stable response (limit cycle) in sense of lyapunov[4].brad s.liebst studied the trigger mailto:emadaabd@yahoo.com mailto:dr_qasim_uot@yahoo.com mailto:alitalib84@gmail.com emad n.abdulwahab al-khwarizmi engineering journal, vol. 9, no. 1, p.p. 29-38 (2013) 30 parameter and a simple procedure developed to predict the onset of a wing rock [5].chung-hao hsu studied the aerodynamic mathematical model to calculate the wing rock characteristics. the resulting nonlinear flight dynamics equations of both one and three degree of freedom are solved with beecham-titchener asymptotic method for limit cycle amplitude and wing rock frequency[6]. emad n. studied the behavior of a limit cycle wing rock motion resulting from new couple effect including dihedral effect derivative and directional stability derivative[7]. the present work focused on the variation of the aircraft state variables limit cycle amplitude at different values of the angles of attack. the numerical results indicated that the system became more lightly damped at an angle of attack α = 20° − 23° . the variation of lyapunov exponent parameter as a function of time to predict the stability of aircraft is presented. 2. aerodynamic model the high performance baseline aircraft, f-15 with mach number=0.6 and height=10.6 km, was taken into consideration in the present work. the aircraft fixed-coordinate systems, geometrical configuration, inertia properties and the aerodynamic model are a hybrid from references [8], [9] and [10].these values are listed in table[a]. summaries of estimated lift coefficient lc , drag coefficient dc are shown in figs. 1 to 2, respectively. table a, geometrical configuration, inertia properties and the aerodynamic model for f-15 aircraft: wing area (m2) 56.485 wing span (m) 13.045 mean chord (m) 4.861 vehicle weight (kg) 18522.44 ixx (kg.m2) 38968.9 iyy (kg.m2) 224172.8 izz(kg.m2) 255130.7 aspect ratio 3.0 3.4385 0.0315 fig. 1. lift coefficient emad n.abdulwahab al-khwarizmi engineering journal, vol. 9, no. 1, p.p. 29-38 (2013) 31 fig. 2. drag coefficient the aerodynamic model is based on the representative experimental and flight test data [8].the stability derivatives are estimated according to the mathematical relations: stability derivatives of equations: = …(1) = …(2) = − ( + ) …(3) = …(4) = …(5) = …(6) = …(7) = …(8) = …(9) = …(10) 3. nonlinear equations of motion model the aircraft simulation model represents f-15 fighter aircraft which is considereda nonlinear modal in flight dynamics system. therefore, the behavior of the flight regime model aircraft may consider the limit cycle or another periodic motion. the wing rock is one of the limit cycle motions. the aircraft model (f-15 fighter aircraft) is a nonlinear state space system, considering small perturbations around the trim conditions. the lateral-directional system in general form can be defined as [11]: ̇ = [ ]{ } +[ ]{ } … (11) where [ ] = lateral-directional plant matrix, [ ] = control effectiveness matrix, { } =lateral-directional state vector, [ ∅ ] , { } = control input, [ ] ; is the sideslip angle, p is the roll rate, is the roll angle, ris the yaw rate and , are the rudders, aileron control angles, respectively. if only rudder or aileron control were under consideration, then the control input would simplify to a single (scalar) value. the uncoupled set of nonlinear equations of motion was [12]: ̇ = [ ]{ } …(12) ̇ = …(13) and =longitudinal state vector,[ ] . the lateral-directional plant matrix was defined by: [ ] = ⎣⎢⎢ ⎡ ⁄ 0.0 (g cos ) ⁄ −1 0.0 0.0 1 0.0 0.0 0.0 ⎦⎥⎥ ⎤ and = ⁄ 1.0 g ⁄ ̇ where is the change in side force caused by a variation in thesideslip angle, is the dihedral emad n.abdulwahab al-khwarizmi engineering journal, vol. 9, no. 1, p.p. 29-38 (2013) 32 effect, is the roll damping, is the change in rolling moment caused by yawing, is the directional stability, is the change in yawing moment caused by rolling, is the yaw damping, u is the free stream velocity, is the normal force due to angle of attack, is the pitch rate, is angle of attack, is the longitudinal stability derivative and is the pitch damping. in full set of equations, the small angle assumption for motion about an initial level of flight condition was removed and aneuler angle relation was introduced. roll angle, became the euler angle θwhile the pitch angle, , became the euler angle θ [4]. the nonlinear relations listed below were added to corresponding terms in eqs. (2), (3) to obtain a full set of motion expressions. the nonlinear additions are denoted by (nl) with the subscript denoting the nonlinear expression to which it is applied. thus, ( ) = + θ θ …(14) ( ) = ( − ) ⁄ …(15) ( )∅ = φ + θ …(16) ( ) = ( ) …(17) ( ) = − + θ θ …(18) ( ) = + ( − ) + ( ) ⁄ …(19) in eqs. (4)– (9), trigonometric terms are shown as φ = cos φ, φ = sinφ , θ = cos θand θ =tan θ an euler angle relationship for θ̇was introduced by: θ̇ = φ − φ …(20) the nonlinear set of motion relations were obtained by including eqs. (4)–(9) as an additional set of terms added to eqs. (2)– (3). in addition, a seventh relation was added, eq. (10), to account for the dynamics of the euler angle θ. as a result, the state vector for the nonlinear system became: { } = [ φ θ] …(21) the time history of the complete set of nonlinear motion equations was solved. 4. lyapunov exponent criterion in order for a system to exhibit a chaotic behavior, it must be non-linear, sensitive to varying parameters and it initial conditions. predictive criteriasuch as periodic doubling criteria, chirikov’s overlap criteria [12], or lyapunov exponent criteria [13] were used to describe the chaotic behavior of the non-linear dynamic system in the present paper, the lyapunov exponent criteria will be considered to describe the chaos behavior of non-linear state equations. consider an attractor point and a neighboring attractor point + . then, the iterated map function is applied n times to each value and the absolute value of the difference between those results is considered: = ( )( + ) − ( )( ) …(22) if the behavior is chaotic, this distance is expected to grow exponentially with n, so = ( )( ) ( )( ) ≡ …(23) or = ln | ( ) ( )| …(24) whereλ,is lyapunov exponent for the trajectory. applying the chain rule for differentiation, the derivative of f (n) can be written as a product of nderivatives off (x) evaluated at successive trajectory points , , , and so on. thus, the definition of lyapunov exponent in a more intuitive form is = ln ′( ) ′( ) … ′( ) …(25) where ′( ) = ⁄ …(16) also, one can rewrite equation (16) as = ln ′( ) + ln ′( ) + ⋯+ ′( ) …(27) when < 0: the orbit attracts to a stable periodic orbit. = 0: the orbit is a neutral fixed point (a bifurcation occurs). > 0: the orbit is unstable and chaotic. emad n.abdulwahab al-khwarizmi engineering journal, vol. 9, no. 1, p.p. 29-38 (2013) 33 5. result and discussion a baseline aircraft f-15 is taken into consideration in this analysis with mach no. =0.6 at h=10.6 km.to demonstrate the state variables in a wing rock phenomenon, the nonlinear equations of motions at high angles of attack were solved.in this study, the wing rock limit cycle f15 is characterized by modifying the directional stability derivatives in a plant matrix. a buildup of roll angle to limit cycle oscillation can be found in fig. 3. with = −0.4 and angle of attack =20 deg. fig. 3. roll limit cycle buildup, ζ=-0.4at α=20 deg. a representative buildup roll and sideslip angles are indicated in fig.5. it can be noted that the amplitude ratio of |φ|: | | = 7.45 with a phase lag of sideslip to roll angle fig.4. fig. 4. limit cycle histories of φ and β, ζ=-0.4 and α=20 deg. a comparative time history of roll angle and angle of attack perturbations during the limit cycle is shown in fig.5. it should be noted that the angle of attack perturbations show a doubling relative the roll limit cycle frequency. this feature, described as kinematic coupling, can be attributed to the terms of eqs. (8) and (9) respectively. an alternate perspective of wing rock limit cycle may be obtained from a cross plot of sideslip angle with roll angle. fig. 5. limit cycle hostories φ and α, ζ=-0.4 and α=20 deg. the trajectory corresponds to amplitude ratio of |φ| to | | that equals to 7.45 and 54.8 phase lag of sideslip relative to the roll angle ,as illustrated in fig.6.it explains that the oscillatory behavior of the map is at a constant amplitude. emad n.abdulwahab al-khwarizmi engineering journal, vol. 9, no. 1, p.p. 29-38 (2013) 34 fig. 6. limit cycle phase trajectory, ζ=-0.4 and α=20deg. fig.7. shows the variation of roll angle amplitude with damping ratio. it is apparent form this figure that the limit cycles, when dutch roll damping less than zero, correspond to a pitchfork type of hopf bifurcation, because the static equilibrium does not exist. fig.7. stability traits of nonlinear oscillator. the effect of dutch roll damping ratio on the roll φ ,sideslip and angle of attack limit cycle amplitudes is shown in fig.8 subject to constraint that the frequency ratio ⁄ was 2 . fig.7. stability traits of nonlinear oscillator. the effect of dutch roll damping ratio on the roll φ ,sideslip and angle of attack limit cycle amplitudes is shown in fig.8 subject to constraint that the frequency ratio ⁄ was 2 . fig. 8. effect of damping ratio on limit cycle amplitude, ζ=-0.4 and α=20 deg. the trend is one of increasing amplitude with increasing levels dutch-roll model damping instability. the effectof frequency ratio ⁄ on the amplitude of roll, sideslip and angle of attack is displayed in fig.9. emad n.abdulwahab al-khwarizmi engineering journal, vol. 9, no. 1, p.p. 29-38 (2013) 35 the minimum value of the amplitude is obtained at an optimal value of ⁄ =2.0 and that explains that ability of the longitudinal motion to couple and transfer energy for creation of a stable limit cycle. fig. 9. effect of frequency ratio on limit cycle amplitude, ζ=-0.4 and α=20 deg. the variation of the roll limit cycle amplitude at different angles of attack is presented in fig.10. this figure shows the upper and lower values of the roll limit cycle as function of angle of attack. fig. 10. variation limits cycle amplitude (φ) at different angle of attack. the verification of the limit cycle existence ( = 0) at different values of angles of attack can be indicated in fig. (11-14). fig. 11. lyapunov exponent values (verification l.c.o) at α=20 deg. fig. 12. lyapunov exponent values (verification l.c.o) at α=21 deg. fig. 13. lyapunov exponent values (verification l.c.o) at α=22 deg. emad n.abdulwahab al-khwarizmi engineering journal, vol. 9, no. 1, p.p. 29-38 (2013) 36 fig. 14. lyapunov exponent values (verification l.c.o) at α=23 deg. fig. 15. trigger parameter vs aoa for f-15. 6. conclusions the characterization of the limit cycle oscillation in aircraft lateral dynamics is presented in this paper. based on lyapunov exponent criterion, the stability of aircraft in critical cases is displayed. the following conclusions wear obtained in the current work: 1. the system became more lightly damped at a high angle of attack and the influence of the aircraft roll damping on the behavior of the limit cycle was found to be weak. 2. the variation of lyapunov exponent parameter as function of time is obtained. this will enable the tracking of aircraft stability.once an indication of stability limit, the controller can intervene to bring it back to a steady state without having to consider the final value of lyapunov parameter which is implemented in other methods and theories. 3. a good agreement between the numerical result and published work is obtained for the onset of limit cycle oscillation [14], as represented in fig.16. 7. references [1] g.guglierif.quagliotti, experimental observation and discussion of the wing rock phenomenon, j.aerospace science and technology, no.2, pp.111-123, 1997. [2] andrew s.arena jr,robert c.nelson. experimental investigations on limit cycle wing rock of slender wings,j.ofaircraft, vol.31,no.5,pp.1148-1155,sept-oct.1994. [3] raul ordonez, kevin m.passino.regulation with a time-varying angle of attack, intelligent control, proceeding of the ieee international symposium,pp.145-150,2000. [4] emad n.abdulwahab and chen hongquan.periodic motion suppression based on control of wing rock in aircraft lateral dynamics, aerospace science and technology,vol.12,issue 4,pp.295-301,2008 [5] brad s.liebst and robert c.nolan. method for prediction of the onset of wing rock, j.ofaircraft, vol.31, no 6, pp.14191421,1991. [6] chung-hao hsu, c.edward lan.theory of wing rock, aiaa paper, vol.22, no.10, pp.920-924, 1985. [7] emad n.abdulwahab, chen hongquan.limit cycle oscillation and divergence behavior of new coupled stability effects in aircraft lateral dynamics, vol.3, no.1, pp.1-13, 2008. [8] euclidc. holleman, edwards.s ummary of flight test to determine the spin and controllability characteristics of a remotely piloted, larage scale (3/8) fighter airplane model.national aeronautics and space administration,washington,d.c.nasa tn d8052,january 1976. emad n.abdulwahab al-khwarizmi engineering journal, vol. 9, no. 1, p.p. 29-38 (2013) 37 [9] kennetb w.iliff,richard e.maine,mary f. shafer,edward.subsonic stability and control derivatives for unpowered,remotely piloted (3/8) scale f-15 airplane model obtained from flight test. national aeronautics and a space administration, washington, d.c.nasa tn d-8136,january 1976. [10] randal w. brumbaugh.an aircraft model for the aiaa controls design challenge. contract nasa 2-12722,december 1991. [11] l.v. schmidt, introduction to aircraft flight dynamics, aiaa education series, naval postgraduate school, monterey, ca, 1998. [12] guckenheimer, j. and holems, p.nonlinear oscillations, dynamical systems, and bifurcations of vector fields, (springerverlag, newyork),1983. [13] hilborn, robert, c.chaos and nonlinear dynamics: an introduction for scientists and engineers, (oxford university press, usa),2000. [14] brad s. liebst and robert c.nolan, method for prediction of the onset of wing rock, j. aircraft, vol. 31, no. 6, pp. 1419-1421, 1994. )2013( 2938، صفحة 1، العدد9مجلة الخوارزمي الھندسیة المجلدعماد ناطق عبد الوھاب 38 األسیةاالستقراریة الجانبیة العرضیة للطائرة في الحاالت الحرجة حسب نظریة لیبنوف ***طالب عبد الزھرة يعل** قاسم عباس عطیة* عماد ناطق عبد الوھاب الجامعة التكنولوجیة /عداتقسم ھندسة المكائن والم***،**،* emadaabd@yahoo.com رید االلكترونيالب: * dr_qasim_uot@yahoo.com االلكتروني البرید: ** alitalib84@gmail.com *** :االلكتروني البرید الخالصة تم وصف الحركة الدوریة أو . األتجاھیة أثناء حاالت الطیران الحرجة بأعتماد نظریة لیبنوف األسیة الحالي تحلیل األستقراریة الجانبیةیتناول البحث اھیة غیر حیث كانت األلیة المتبعة للدورة المحددة لتأرجح الجناح ھي ربط القصور الذاتي بین طور الحركة الجانبیة األتج. التذبذب ذو الدورة المحددة تم تحقیق ألیة الربط ھذه بواسطة التداخل الالخطي بین الحدود ذات العالقة في ). لفترة قصیرة(وطور الحركة الطولیة المستقرة ) األلتفاف الھولندي(المستقرة جوم عالیة وتم أقتراح أسلوب جدید للتحلیل تم تحلیل متغیرات الحالة للنظام عن طریق حل معادالت الحركة الالخطیة عند زوایا ھ. معادالت الحركة الكاملة یصبح ذات تخمید ) الطائرة(أظھرت النتائج العددیة بأن النظام . یضمن تغیر زاویة األلتفاف كدالة لزاویة الھجوم أضافة لتغیر معامل لیبنوف كدالة للزمن م الحصول على توافق جید بین نتائج البحث الحالي و نتائج ألبحاث ت. ضعیف عند زوایا الھجوم العالیة مع زیادة في سعة متغیرات الحالة ذات العالقة .لمنشورة عند نشوء التذبذب ذو الدورة المحددة mailto:emadaabd@yahoo.com mailto:dr_qasim_uot@yahoo.com mailto:alitalib84@gmail.com al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 7, no. 2, pp 68 74 (2011) extraction of zn (ii) and cu (ii) ions using peg (300) kcl salt aqueous two-phase systems saad h. ammar * waqar abdul-wahid abdul-nabi ** musaab khadem rasheed *** *, ** department of chemical engineering/ university of al-nahrain * email: saad_cheminet@yahoo.com *** technical institute/ baghdad (received!21 october 2010; accepted 19 april 2011) abstract in this paper the process of metal ions extraction (zn(ii) and cu(ii)) was studied in peg-kcl aqueous two phase system was investigated without using an extracting agent. the experimental runs were performance at constant temperature (25 oc), constant mixing time (30 min), and constant ph of the solution (about 3). the effect of kcl salt concentration (from 10% to 25%), volumetric phase ratio of peg solution to kcl solution (from 0.5 to 2), and the initial metal ion concentration (from 0.25 ml to 2 ml of 1 gm/l solution) were investigated on the percent extraction of zn(ii) and cu(ii). the results indicated that the percent extraction of metal ions increase with increasing of salt concentration and phase ratio, and slightly decrease with increasing of initial metal ion concentration. keywords: liquid-liquid extraction, aqueous two phase system, metal ions, waste water. 1. introduction aqueous two-phase systems formed when a water soluble polymer is mixed with a certain inorganic salt (e.g. (nh4)2so4, na2so4, na2co3, k2hpo4, kcl), may represent an alternative for metal ions extraction processes in industrial separation, as well as environmental remediation applications. (laura bulgariu, 2008) many different water soluble polymers may be utilized to form aqueous two-phase systems (atps), poly ethylene glycol (peg) is exclusively used because it is non-toxic, nonflammable and non-volatile (graber, t.a at. el., 2000). rogers et al. classified metal ion extractions in the aqueous two-phase` systems into three categories: (1) extraction using a water-soluble extractant; (2) extraction of metal complexes of inorganic anions and (3) extraction by the pegrich phase alone without an extractant. among these three categories, the second type of metal extraction will find wide application to soft metal ions, which form complexes with halide or pseudohalide anions (rogers, 1993 and rogers, 1995). the extraction of a metal ion mm+, with a complexing anion, x−, can be described as (shibukawa at. el., 2001): …(1) …(2) where β and kd are the stability constant and the distribution coefficient of the metal complex, respectively. most of the metal ions studied are extracted as anionic complexes as so that sodium ion or potassium ion may distribute into the top phase as their counter ion. a preliminary experiment showed that the dependence of the distribution of metal ions on the amount of h2so4 added was this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ saad h. ammar al-khwarizmi engineering journal, vol. 7, no. 2, pp 68 74 (2011) 69 very small. this result suggests that the coextraction of hydrogen ion with the anionic complexes can be neglected. sulphate ion has the ability to form complexes of a number of metal ions so that the complexation reaction of the metal ions with so4 2− may not be negligible especially in the na2so4-rich phase: …(3) …(4) consequently the distribution ratio of a metal ion, d, defined as the ratio of the metal concentration in the peg-rich phase to that in the na2so4 rich phase can be given by …(5) it is reasonable to assume that [m(so4)x 2x−m]peg << [mxn n−m]peg since the metal ions are scarcely extracted into the peg-rich phase in the absence of scn− or i−. this may be due to small kd values of the metal sulphate complexes. therefore, eq. (2.25) can be rewritten as: …(6) the extraction of metal ions in presence of inorganic extractants, with aqueous peg– inorganic salt two-phase systems, can be represented by a succession of equilibriums, schematically presented in fig. (1). the metal ion, initially present in salt-rich phase as anionic or neutral species (mam y−; a –phase-forming anion) will interact with inorganic extractants, most probably at interface, and the formed species (mxn x−) will be then partitioned into peg rich phase. the formation of extractable species occurs step by step, until his hydration degree becomes comparable with the hydration environment of peg-rich phase from extraction system. in function of the stability of metallic species formed with phase-forming anion (βmay− m) and with inorganic extractant (βmxnx−), the following three situations are possible (laura bulgariua, at. el., 2008). fig.1. schematic representation of equilibriums involved in metal ions extraction with inorganic extractants, in aqueous peg–inorganic salt two-phase systems. (a− –phase-forming anion; x− – inorganic extractant) (laura bulgariua, at. el., 2008). after inorganic extractants addition, the metal ions from this category form, even in salt-rich phase, halide species with the mention that the number of halide ions from metallic species is minimum. these species are marginalized in the salt-rich phase, due to their low hydration, and this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ saad h. ammar al-khwarizmi engineering journal, vol. 7, no. 2, pp 68 74 (2011) 70 remitted at interface. here, they will interact with more halide ion extractants and will form anionic complexes with higher number of halide extractant in molecule. because the hydration degree of these anionic complexes is lower and compatible with the hydration environment of peg-rich phase, their partition occurs immediately and this is quantitative one. the anionic species formed at interface, cross like they are into peg-rich phases, where they will interact predominantly by ionic forces with the other oxygen atoms from peg molecules. these interactions affect only the bridging water molecules. fig.2. schematic representation of anionic complexes (mxn x−) extraction in aqueous peg– inorganic salt two-phase system (laura bulgariua, at. el., 2008). the breaking of hydrogen bonds between peg chains and water molecules determined the decrease of polymer chains interaction and the modification of water molecules binding way on polymer macromolecules. the formation of ordinate micro-domains is due to the interaction of anionic extracted species with peg molecules, which determined a linearization of polymer chains. probably, a plane square geometry of metal species is preferred due to this reason. in the same time with the transfer of anionic species into pegrich phase, the forming-phase anions (so4 2-) that have accompanied the formation and the separation of the two aqueous phases are expulsed in salt-rich phase, due to the incompatibility of hydration environment, and the phases are maintained neutral from electrical point of view. the ir spectra and microscopic images indicate that the extracted species, indifferently by their type (anionic complexes or neutral molecules) cross in peg-rich phase of extraction system and are “fixed” by characteristic interactions. thus, in case of anionic species extraction, the ir spectra show that between metal extracted species and peg molecules strong interactions occur, and the bridging water molecules are used as intermediary. here, the peg-rich phases are formed predominantly, from micro-domains with high ordination degree. in case of neutral molecules extraction, the changes observed in ir spectra can be attributed to the formation of some new hydrogen bonds between extracted species and peg chains. in consequence, the microscopic images show that in the solidified peg-rich phases of these systems the micro-domains with a lower ordination degree are predominant, which has an organization way and some characteristics similar to the colloidal systems. a schematic representation of cd(ii) extraction in the presence of halide ions in the considered aqueous two –phase system is presented in fig. (3) according to this, for partition cd(ii), processes which occur at the peg-rich phases/salt-phase interface are essential: cd(ii) complexation with halide ions and the transformation of cadmium halide species into complex species towards the peg-rich phase have a higher affinity under the employed conditions (laura bulgariua, at. el., 2008). fig.3. schematic representation of the main processes involved in cd (ii) extraction in the considered aqueous two-phase system (laura bulgariua, at. el., 2008). the anionic species formed at the interface cross into the peg-rich phase, where they will interact, predominantly by ionic forces, with the top phase (rich in peg) bottom phase (rich in inorganic salt) in te rf ac e this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ saad h. ammar al-khwarizmi engineering journal, vol. 7, no. 2, pp 68 74 (2011) 71 atomic absorption spectrophotom -eter peg solution kcl solution shaking 30 min metal ion solution centrifugation bottom phase top phase ether oxygen atoms of peg. an equivalent ionic transfer process ensures the electro neutrality of the two phases. in case of extraction of cd(ii) anionic complexes, the so4 2ion which are present in the peg-rich phase after formation of the aqueous two-phase system are expelled into the salt-rich phase, due to the incompatibility of the hydration environment. thus, the phases are kept neutral from an electrical point of view and the hydrophobicity of the peg-rich phase is maintained during of extraction process. in this study, the extraction of zn(ii) and cu(ii) metal ions in peg-kcl aqueous two phase system was investigated without using an extractant. the effect of salt concentration, volumetric phase ratio of peg solution to kcl solution, and initial metal ion concentration on the percent extraction of zn(ii) and cu(ii) were investigated. fig.4. experimental procedure steps 2. materials and methods the peg used in this study was peg-3000 (average molecular weight, 3000). stock solutions of 30% (w/w) peg were prepared by dissolving of suitable quantity of peg in deionized water. the stock solutions of inorganic salt at different values (10%, 15%, 20%, and 25% (w/w) kcl) were prepared by dissolving the required amount of salt in deionized water and at constant ph value (about 3) by adding small volumes of acids or bases concentrated solutions. the 1 gm/l solution of metal ions (zn(ii) and cu(ii)) was obtained by metal sulphate salt dissolving in deionized and distillate water, the initial metal ion concentration was varied by taking 0.25, 0.5, 1 and 2 ml of the 1 gm/l metal ion solution prepared. for each experiment, an aqueous two-phase system was prepared by mixing the prespecified volumetric phase ratio of peg stock solution – kcl salt stock solution in the range of 0.5, 1, 1.5, and 2 with constant ph of 3 at room temperature (25±2 oc). the (0.25–1.5) ml of 1 gm/l metal ion (zn(ii) and cu(ii)) solutions were added and the system was shaken for 30 minute followed by 15 minute of centrifugation. equal volumes (1 ml) for each phase were separated and measured for zn(ii) and cu(ii) ions by means of atomic absorption spectrometer (type perkin – elmer 5000 in ibn-sina state company, baghdad). figure (4) show the experimental procedure steps. 3. results and discussion 3.1. effect of concentration of kcl figure (5) shows the percent extraction of metal ions (zn(ii) and cu(ii)) as a function of concentration of kcl in the stock solution (10%, 15%, 20%, and 25% (w/w) kcl) at phase ratio of 1 and initial metal ion concentration of 0.5 ml of 1 gm/l. it is clear from this figure that the percent extraction of metal ions increase with increasing of kcl concentration in salt phase. fig.5. percent extraction (%) of metal ions as a function of concentration of kcl in the stock solution % (w/w) at phase ratio of 1 and initial metal ion concentration of 0.5 ml of 1 gm/l. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ saad h. ammar al-khwarizmi engineering journal, vol. 7, no. 2, pp 68 74 (2011) 72 the formation of aqueous two-phase system of peg and a certain inorganic salt can be explained on the basis of the competition for hydration between the two components. the addition of an inorganic salt increases the dehydration of the polymer chains, due to the salting-out effect and phase separation (laura bulgariu, 2005). 3.2. effect of the (peg/kcl) phase ratio figure (6) shows the percent extraction of metal ions (zn(ii) and cu(ii)) with the volumetric phase ratio of peg to kcl (0.5, 1, 1.5, and 2) at constant kcl salt concentration in stock solutions of 20% (w/w) and initial metal ion concentration of 0.5 ml of 1 gm/l. fig.6. percent extraction (%) of metal ions as a function of phase ratio at kcl concentration in stock solutions of 20% (w/w) and initial metal ion concentration of 0.5 ml of 1 gm/l. the results above indicate that the extraction of the metals above increases with increasing of peg/kcl volumetric phase ratio. this might be attributed to the increase in the quantity of transferred metal which is related with quantity of the extractant that will furnish the necessary molecules to form the complex to reach the equilibrium state (graber, t.a., 2007). 3.3. effect of initial metals concentration figure (7) shows the percent extraction of metal ions as a function initial metal concentration in the salt phase at phase ratio of 1 and kcl salt concentration in the stock solution of 20% (w/w). as notices from the results that plotted in figure (7), increasing the metals concentration in the feed, the percent extraction of metal removed decrease. fig.7. percent extraction (%) of metal ions as a function of initial metal ion concentration at phase ratio of 1 and kcl salt concentration in the stock solution of 20% (w/w). 4. conclusion the process of zn(ii) and cu(ii) metal ions extraction was studied using aqueous peg – kcl salt two phase systems without using an extractant agent. the process variables salt concentration in the salt phase, peg/kcl volumetric phase ratio, and the initial metal ions concentration were studied on the percent extraction of metal ions. the results indicated that the percent extraction of metal ions increase with increasing of salt concentration and phase ratio, and slightly decrease with increasing of initial metal ion concentration. 5. references [1] graber, t.a., andrews, b.a; asenjo, j.a., “model for the partition of metal ions in aqueous two phase systems” j. chromatoger., 2000. [2] graber, t.a., medina, h., "phase equilibrium and partition of iodide in an aqueous biphasic system formed by (nh) so+peg+ho at 25oc", j. of chemical and engineering data, p1262-1267, 2007. [3] masami shibukawa, noriko nakayama ,tadashige hayashi, daigo shibuya,yukihiro endo, "extraction behaviour of metal ions in aqueous polyethylene glycol–sodium sulphate two-phase systems in the presence of iodide and thiocyanate ions", japan, analytica chimica acta 427(2001)293–300. [4] laura bulgaria, dumitru bulgariu, "extraction of metal ions in aqueous polyethylene glycol –inorganic salt two this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ saad h. ammar al-khwarizmi engineering journal, vol. 7, no. 2, pp 68 74 (2011) 73 phase systems in the presence of inorganic extractants: correlation between extraction behavior and stability constants of extracted species" journal of chromatography a, 117124, 2008. [5] laura bulgariu, dumitru bulgariu, "the extraction of zn(ii) in aqueous peg (1550)(nh4)2so4 two phase system using clions as extracting agent", 2005. [6] laura bulgariua , dumitru bulgariu , extraction of metal ions in aqueous polyethylene glycol–inorganic salt two-phase systems in the presence of inorganic extractants: correlation between extraction behaviour and stability constants of extracted species, journal of chromatography a, 1196–1197 (2008) 117–124 [7] laura bulgariu and dumitru bulgariu , “cd(ii) extraction in peg(1550)– (nh4)2so4 aqueous two-phase systems using halide extractants”, romania journal of the serbian chemical society 73 (3) 341350 (2008). [8] rogers r.d., a.h. bond, c.b. bauer, sep. sci. technol. 28, 1091 (1993). [9] rogers r.d., a.h. bond, c.b. bauer, j. zhang, m.l. jezl, d.m. roden, s.d. rein, r.r. chomko, in: r.d. rogers, m.a. eiteman (eds.), aqueous biphasic separations: biomolecules to metal ions, plenum press, new york, , p. 1 (1995). this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ 74 ، صفحة2، العدد 7مجلة الخوارزمي الھندسیة المجلد سعد حنش عمار 68 )2011( 74 الزنك بأستخدام انظمة المحالیل المائیة ثنائیة الطوروالنحاس یوناتأستخالص أ ملح كلورید البوتاسیوم ) ٣٠٠٠(بولي اثلین كالیكول المتكونة من *** مصعب كاظم رشید** وقار عبدالواحد عبدالنبي * سعد حنش عمار ویة** ، * لكیمیا ا ھندسة ال لنھرین/ قسم ا جامعة saad_cheminet@yahoo.com: رید االلكترونيالب* بغداد /المعھد التقني*** الخالصة كلورید ملحوبولي اثلین كالیكول في أنظمة المحالیل المائیة ثنائیة الطور والمتكونة من ) الزنكو, النحاس(أستخالص أیونات المعادن عملیةتم دراسة تم .)افة لكونھ مكون للطور الملحيحیث ان ملح كلورید البوتاسیوم یعمل كعامل أستخالص باالض(وبدون استخدام عوامل استخالص kclالبوتاسیوم لمتغیرات التالیة على تم دراسة ا). 3بحدود ( المحلول ثابت phو ) دقیقة 30(زمن الخلط ثابت , )درجة مئویة 25(اجراء التجارب تحت درجة حرارة ثابتة :نسبة االستخالص  تركیز الملحkcl وزنا% 25الى % 10في الطور الملحي من.  2الى 0.5من ) طور محلول ملح كلورید البوتاسیوم/ طور محلول البولي أثیلین كالیكول(نسبة الطور الحجمیة.  لتر/ غرام 1ملیلتر من تركیز 2الى 0.25 بینویتراوحالتركیز االبتدائي الیونات المعدن. ح ) النحاس والزنك(اظھرت النتائج أن النسبة المئویة الستخالص أیونات المعادن ي kclتزداد بصورة رئیسیة بزیادة كل من تركیز مل ور الملح ي الط ف .ونسبة الطور بین البولیمر والملح وتقل مع زیادة التراكیز االبتدائیة ألیونات المعادن this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ خير الله سلمان al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 8, no.4, pp 9095 (2012) analysis of the effects of aggressive shot peening on fatigue life of 7075 – t6 aluminum alloy khairallah s. jabur department of mechanical/ institute of technologybaghdad email: a_khairallah@yahoo.com (received 29 november 2011; accepted 7 august 2012) abstract for many years controlled shot peening was considered as a surface treatment. it is now clear that the performance of control shot peening in terms of fatigue depends on the balance between its beneficial (compressive residual stress and work hardening) and beneficial effects (surface hardening). the overall aim of this paper is to study the effects of aggressive shot peening on fatigue life of 7075 – t6 aluminum alloy. the fatigue life reduction factor (lrf) due to the aggressive shot peening was established and empirical relations were proposed to describe the behavior of lrf, roughness and fatigue life. the benefits of shot peering in terms of fatigue life are dependent on the shot peening time (spt). the higher spt is the lower the benefit is. higher roughness results in lower fatigue life. keywords: aggressive shot peening, fatigue life , lrf , 7075 – t6 al-alloy. 1. introduction and review shot peening treatments are widely used in mechanical and aeronautical engineering to improve the fatigue performance of components . there have however been reports of extensive variations in the fatigue life results for peened components and , in some cases a decrease in fatigue life has been observed [1] . peening attempts to spread material near the impact point against the resistance of neighboring material , thus introducing a complex subsurface residual stress distribution in which generally , the surface is in elastic compression . there is a rapid transition to elastic tension at a deeper level , produced by the "enlarged" surface layer . this tension decays in deeper regions towards zero as shown in figure (1) [2] . significant effect of peening intercity on fatigue life is also been noted ; there appears to be an optimum peening intensity to achieve the longest improvement in fatigue life .this intensity varies with the type of aluminum and heat treatment [3] [4] . fig. 1. schematic of residual stress distribution below a peened surface. compressive layer generally extends 200 – 400 µ m below the surface [2]. alalkawi et al. studied the effect of shot peening on two aluminum alloys 2024 and 5052 . the cumulative fatigue life of 2024 aluminum alloy is increased by shot peening while the mailto:a_khairallah@yahoo.com khairallah s. jabur al-khwarizmi engineering journal, vol. 8, no.4, pp 9095 (2012) 91 fatigue life of 5052 aluminum alloy is reduced due to high surface roughness and consequently high tensile residual stresses [5] . the predictions of the continuum damage modeling (cdm) were compared to the experimentally observed mechanical response and to the micromechanical characterization of damage. the comparison showed good agreement for 2024 – t351 aluminum alloy plate subjected to multi – acid stress states [6] . aggressive shot peening tends to increase the surface roughness which can be detrimental to fatigue performance . the higher roughness creates short crack growth and reduce the fatigue life [7] [8] . this paper discusses the fatigue behavior of 7075 – al – alloy under different shot peening times (spt) and summarizes the improvements in peening arisen from this research. 2. material aluminum alloy aa 7075 – t6 is used in the present work which has low specific weight and high strength to weight ratio. this alloy is widely used in industry and in particular in aircraft structure and pressure vessels [9] is presented in table (1) chemical composition of 7075 – t6 al – alloy wt% [10] ; while the mechanical properties were effected at the center of standardization and quality control are illustrated in table (2) . table 1, chemical composition of 7075 – t6 al – alloy wt%. si fe cu mn mg zn cr al 0.16 0.32 1.8 0.1 2.3 5.4 0.2 rem table 2, mechanical properties of 7075 – t6 al – alloy. properties σ u (mpa) σ y (mpa) ei % hb experimental 600 521 11 158 standard 570 505 9 150 3. fatigue testing specimens all fatigue specimens were prepared according to din 50113. the shape of the fatigue specimen is hour – glass type in order to obtain stress concentration in the middle of the specimens (minimum diameter). fig. (2) shows the fatigue specimen configuration fig. 2. fatigue specimen (all dimensions in mm) according to din 50113. 4. shot peening shot peening was carried out for different times using spherically ball of 1mm in diameter at constant distance between the nozzle and the specimen of 10 cm. the specimen is rotating continuously during peening to ensure 100% coverage. shot peening technique was performed using spherical steel balls of 1mm diameter. the ball hardness is 48 – 50 hb 12 bar average blasting pressure, the ball speed is 40 m/s , 100% coverage . the shot peening device used was (shot tumblast control model stb – ob) machine no. 03008 05 type. fig (3) shows the shot peening device with shot balls used. khairallah s. jabur al-khwarizmi engineering journal, vol. 8, no.4, pp 9095 (2012) 92 (a) (b) fig. 3. (a) shot peening device. (b) shot balls. 5. roughness measurement surface roughness measurements were carried out at the labs, of malaysia pahang university using surface roughness testing machine type perthometer 52. more details can be found in ref [11] . table (3) gives the average roughness (ra) for different conditions of shot peening time (spt). table 3, average roughness before and after (spt) for 7075 – t6 al. alloy. spt (min.) ra (µm)* spt (min) ra (µm) zero** 0.25 35 4.6 15 2.5 45 5.5 25 3.8 55 6.7 * the data are an average of 5 readings. ** zero spt i . e before shot peening or as received. 6. fatigue life tests 12 specimens are tested under constant rotating bending amplitude stress , 0.6 σ u (360 mpa) , and at room temperature with stress ratio r = -1 . table (4) shows the experimental results versa surface roughness (ra) and spt . table 4, comparison of fatigue life and surface roughness for a number of spt. spec. no. spt (min) surface roughness ra ( mµ ) fatigue life , nf cycles 1 , 2 0 0.25 62800 , 59200 3 , 4 15 2.5 200600 , 188000 5 , 6 25 3.8 52800 , 57900 7 , 8 35 4.6 41200 , 39600 9 , 10 45 5.5 30800 , 32600 11 , 12 55 6.7 28000 , 26700 the results appear to show a direct correlation between spt and fatigue life of peened 7075 – t6 al. alloy. as spt increases (from zero to 15 spt) the fatigue life increases. but as roughness increases, fatigue life decreases (from 25 to 55 spt). it is therefore considered that it might be possible to quantify the effects of peening on fatigue life by measuring surface roughness. the conclusion, at this stage is that some correlation exists between roughness and fatigue life for spt from 25 to 55 , but where khairallah s. jabur al-khwarizmi engineering journal, vol. 8, no.4, pp 9095 (2012) 93 the history of the part may have included some peening , from zero to 15 spt , this relationship is unreliable . fig (4) shows the roughness against fatigue life for spt from 25 to 55. the best fit formula which deseribes the above relation can be written by the empirical equation ra =22803 nf -0.8 …(1) fig. 4. the relationship between measured (ra) and fatigue life nf for 25 to 55 spt. based on the results of table (4), the mean life improvement factor (lif) for spt 15 minutes is 3.185 . this value is obtained from table (4) as nf average 15spt 194000 lif= -------------------------= -------- = 3.185 nf average zero spt 61000 which obays the work of sharp , et al. [12] . they proposed formula which described the relation between lif and applied stress based on the experimental results for aluminum alloys as: lif=6*1015(stress)-5.8749 …(2) at 400 mpa sharp et al. found that the lif was 3.192 at the same spt used in this work. for spt 25 to 55 the effect of peening is inversially proportional to fatigue life, i . e when spt increases the fatigue life decreases . because of the greater damage to the material, the surface finish (roughness and defects) is also recognized as a critical influence on fatigue life. the lrf (life reduction factor) for specimens peened at spt 25 to 55 is tabulated in table (5) table 5, lrf due to high spt. spec. no. average life cycles average (ra) µm lrf * 5 , 6 55350 3.8 1.102 7 , 8 40400 4.6 1.509 9 , 10 31700 5.5 1.924 11 , 12 27350 6.7 2.230 * lrf is calculated based on unpeened average fatigue life 61000 (specimens 1,2). the results of table (5) appear to a direct relation between surface roughness and lrf of peened aluminum alloy 7075 – t6 . as (ra) increases, lrf increases as shown in figure (6). it is clear that the relation between lrf and nf is inversely proportional as shown in the formula: lrf = 89743 nf -1.037 …(3) 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 series1 theo fig. 6. roughness against lrf for 7075–t6 al – alloy. the problem of excessive or aggressive peening leads to defects buried insub – surface and to very deep laps , which do influence the surface roughness measurement , while greatly reduces fatigue life [13] . the relation which describes the surface roughness with lrf can be written as ra(µm)=3.443lrf0.771 …(4) su rf ac e r ou gh ne ss (r a) µ m nf (cycles) ra =22803 nf -0.8 lrf exp ra = 3.443 lrf0.771 r a (µ m ) khairallah s. jabur al-khwarizmi engineering journal, vol. 8, no.4, pp 9095 (2012) 94 7. conclusions in this work the effects of aggressive spt are analyzed and modeled according to their effects on fatigue life. surface roughness is modeled with fatigue life reduction factor (lrf). the analysis reveals that: 1the benefits of shot peening in terms of fatigue life are dependent on the spt. the higher the spt is the lower the benefit is for time 0 < t < 15 min. 2the fatigue life improvement factor (lif) is limited up to 15 spt and equals to 3.185 . 3after 25 spt, fatigue life is reduced with time and the lrf is appeared. 4after 25 spt , increasing lrf leads to increasing the average roughness (ra) and reducing the average number of cycles for failure (nf) 5an empirical formula which described the relation between (ra) and lrf is proposed as: 771.0)(443.3 lrfra = 8. references [1] clayton j. q. and clark g. " the effect of steel shot and glass bead peening treatments on the fatigue resistance of 7075 – t6351 aluminum alloy " proc. aust. fract. group. fracture mechanics in engineering practice , melbourne , pp. 44-51 , 1988 . [2] p. k. sharp and g. clark " the effect of peening on the fatigue life of 7050 aluminum alloy" dsto , 2001 . [3] luo w, noble , b and waterhouse r. b. " the interaction between shot peening and heat treatment on fatigue and fretting fatigue properties of the high strength aluminum alloy 7075" proc. 2nd int. conf. on impact treatment procedure , 1986 . [4] luo w, noble b and waterhouse r. b. , "the effect of shot peening intensity on the fatigue and fretting behavior of an aluminum alloy " , advances in surface treatment and surface finshing , vol . 5 , pp. 145 – 153 , 1987 . [5] alalkawi h. j. m , qusay kh . m., al – nuami waleed s. " evelation of residual stress using shot cumulative fatigue damage " j. of eng. and tech. , 2009 . [6] s. khan a. vyshnevskyy j. mosler "low cycle lifetime assessment of al 2024 alloy” inter. j. of fatigue 32 , 1270 – 1277 , 2010 . [7] m. a. wahab , j. h. park , m. s. alam , ss. pang. “effect of corrosion prevention compounds on fatigue life in 2024 – t3 aluminum alloy “ jounal of materials processing technology 174 – 211 – 217 , 2006 . [8] y. fouad and mostafa m. el metalally “ effect of shot peening on high cycling fatigue of al – 2024 – t4 , international conference on advanced materials engineering ipcsit vol. 15 , 2011 . [9] g. h. majzoobi , j. nemati , a. j. novin rooz , g. h. farrahi " modification of fretting fatigue behaviors of al 7075 – t6 alloy by the application of titanium coating using ibfd technique and shot peening " tribology inter. 42 , 121 – 129 , 2009 . [10] alakawi h. j. w. , talal abdul – jabbar , safaa h. alokaidi , basil a. selman , ali yousif khenyab , "the effects of dry and wet shot peening on the mechanical and fatigue properties of 7075 – t6 aluminum – alloy" , international journal of engineering research and industrial applications to be published , 2012 . [11] safaa h. a. alokaidi " modeling the fatigue behavior of shot peened aluminum alloys under variable stress range conditions" phd thesis , university of technology , 2011 . [12] sharp p. k. , barter s. a. and clark g. " localized life extension specification for the f / a – 18 y 470x19 pocket " dsto – tn – 0279 , 2000 . [13] alakawi h. j. , kadhim m. j. , selman b. a. , khengab a. y. " improvement of fatigue property in high strength aluminum alloy by shot peening " university umdarunn j. under publication , 2012 . )2012( 9095، صفحة 4، العدد8رزمي الھندسیة المجلد مجلة الخوا خیر اهللا سلمان 95 t6 – 7075تحلیل تأثیرات القذف بالكریات المفرط على عمر الكالل لسبیكة االلمنیوم اهللا سلمان جبر خير بغداد -معھد التكنولوجیا /قسم المیكانیك a-_khairallah@yahoo.com االلكتروني البرید: الخالصة لكالل یعتمد لعدة سنوات عملیة القذف بالكرات المسیطرة كانت تعتبر معاملة سطحیة اما اآلن فتوضح بان اداء عملیة القذف بالكرات المسیطرة بداللة ا ) . لتصلید السطح(وعملیة التصلید السطحي والتأثیرات المفیدة ) الجھادات الضغطیة المتبقیةا(على الموازنة بین ما ھو مفید ت م ایج اد عام ل تخف یض عم ر الك الل . t6 – 7075الھدف الكلي لھذا البحث ھو دراس ة ت أثیرات الق ذف المف رط عل ى عم ر الك الل لس بیكة االلمنی وم )lrf ( نتیجة للقذف المفرط وتم اقتراح عالقات ریاضیة معتمدة على التجارب العملیة لتصف تصرف)lrf ( فوائد القذف بداللة . والخشونة وعمر الكالل .اما زمن القذف الكبیر یعطي فائدة قلیلة وخشونة عالیة والتي تعطي عمر كالل واطىء ) . spt(عمر الكالل تعتمد على زمن القذف بالكریات mailto:a-_khairallah@yahoo.com al-khwarizmi engineering!!! journal al-khwarizmi engineering journal, vol. 7, no. 2, pp 55 67 (2011) evaluating the performance of sharq dijila water treatment plant faris hammoodi al-ani wassel kadum department of building and construction engineering/ university of technology (received 14 november 2010; accepted 24 may 2011) abstract the study aims mainly to evaluate the performance of sharq dijila water treatment plant in removing turbidity for the period of 1-4-2001 to 31-3-2004. daily data for turbidity of raw, clarified, filtered, and supplied water were analyzed. the results of the study showed that there is a wide variation in turbidity levels of raw water fluctuating between 10-1000 ntu with mean value of 41.3 ntu. turbidity values of the clarified water varied between 1.4-77 ntu. based on the turbidity value of 10 ntu and 20 ntu (the design maximum turbidity) the readings gave an acceptable percentage of 32.4% and 86% respectively. the turbidity of filtered water ranged between 0.2-4.5 ntu which are completely in compliance with iraqi and who standards. in accordance with the american environmental protection agency (usepa) and based on the analysis of 2-day moving average of 5 ntu and 30-day moving average of 1 ntu, it was found that the filters operated at acceptable percentage of 100% and 45% respectively. turbidity value of the supplied water averaged between 0.4-9.5 ntu which is higher than the turbidity of the filtered water due to the mixing of the water from all other filters. also turbidity values from the unwashed filters are higher than the washed filters and the precipitation in the treated water reservoir. based on the iraqi drinking water standard, usepa 2-day and 30-day moving average, the supplied water was within the permissible limits of 98%, 98.6%, and 98.6% respectively. key words: treatment plant, turbidity, sharq dijila, raw water, filtered water. 1. introduction the common impurities in water may be classified as physical impurities, chemical impurities, and bacteriological impurities. raw water, especially surface water contains impurities in the form of suspended, dissolved and colloidal solids, bacteria, poisonous substances, color, odor and mineral organic matter. water in reservoirs may be purified to some extent due to storage, but may still contain colloidal matter and bacteria; raw water is undesirable for drinking without treatment. the amount of treatment required depend on the quantity and quality of raw water and required standards of purified water (raju, 1995). water leaving the treatment plant must be safe to drink-free from potentially harmful organisms, aesthetically pleasing-without color and/or turbidity, palatable-devoid of unpleasant taste and/or odor, and chemically stable-as far as is possible, non corrosive (buckley,1984). the performance of each treatment unit affects the efficiency and operation of subsequent units, e.g., increased detention time in flocculation might result in larger flocs formation, better removal in sedimentation, and larger filter runs. the efficiency of a process such as flocculation, sedimentation and filtration depends on the number, size, and mass of the particles in the water to be treated (rammaley et al., 1981). turbidity refers to suspended solids, i.e. muddy water, is very turbid. turbidity is undesirable for three reasons, aesthetic considerations, solids may contain heavy metals and pathogens or other contaminants, and turbidity decreases the effectiveness of water treatment techniques by shielding pathogens from chemical or thermal damage, or in the case of uv (ultra violet) treatment, absorbing the uv lights itself (cheremisinoff, 2002). raw water turbidity can vary over a very wide range, from virtually zero to several thousand ntu. effective treatment should be able to this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ faris hammoodi al-ani al-khwarizmi engineering journal, vol. 7, no. 2, pp 55 67 (2011) 56 consistently produce final waters with turbidity levels of less than 1 ntu. turbidity meters are therefore an essential tool in optimizing and controlling water treatment processes (twort et al., 2009). some surface waters carry loads of sediment so high that water treatment plants employ a presedimentation step prior to the conventional treatment train. the conventional treatment train can treat a wide range of source waters, some may be so challenging that even conventional treatment requires a form of pretreatment (letterman, 1999). the main objective of this study was to evaluate the performance of sharq dijjla water treatment plant. turbidity was selected as a main parameter because it is a conventional treatment plant (did not remove dissolved solids) so turbidity is very important tool in the evaluation of performance. 2. site description and treatment process the sharq dijjla water supply project is one of the two large treated water supply systems in baghdad. it was constructed in 1973 to produce 100 m.g.d and was expanded to 120 m.g.d in 1986 to meet the increasing water demand in russafa side of baghdad. figure1 shows the plan of sharq dijila water treatment plant. the description of treatment plant is (paterson candy international, 1987). fig.1. plan of sharq dijjla water treatment plant. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ faris hammoodi al-ani al-khwarizmi engineering journal, vol. 7, no. 2, pp 55 67 (2011) 57 raw water from the tigris river flows via four bank side intakes, into the raw water pumping station wet sumps. each intake channel is provided with raked bar screen for the removal of trash and debris. vertical spindle pumps lift the raw water from the sumps and delivers, via twin raw water mains, to a division chamber where the total flow is equally divided to serve the two groups of clarifiers. in this position alum solution and pre-chlorination are applied. the aluminum sulphate solution is delivered, via two splitter boxes each of which serves five clarifiers. there are ten clariflocculators dividing into two groups. inside the clariflocculator there is a mixer in order to achieve the required flocculation. sludge which is discharged from the concentrators and the central chamber of each clarifier, flows under gravity to the sludge pumping station. the filters are divided into two groups, which are rapid sand filters with single filtration media consisting of sand supported by gravel. the chlorination unit passes chlorine gas whenever motive water passes through an associated injector; the vacuum produced at the chlorinator gas outlet connection, will pull gas through the instrument. the gas flow can be manually adjusted to the desired rate by means of a control valve. there are three ground baffled tanks, two of which are similar with a capacity of 40,000 m3 and the third of 50,000 m3. these tanks required detention time for chlorine reaction. 3. data analysis and discussion to evaluate the performance of sharq dijila water treatment plant, the raw, clarified, filtered, and supplied water quality are analysed. turbidity data are used in this analysis because this treatment plant is of the conventional type. the data were collected from daily laboratory water quality analysis reports covering the period from1-4-2001 through 31-3-2004. 3.1. analysis of raw water turbidity data figure 2 shows a plot of time series of raw water turbidity data at the intake. this figure shows the drastic changes of turbidity levels in winter while they are more stable in summer and spring. table 1 also shows a statistical description of raw water turbidity data. a wide range of turbidity level is observed which ranges from 10 to 1000 ntu with a standard deviation of 59.5. the mean value is found to be 41.3 ntu, this results in cv of 144.88% which reflects the wide variation in raw water turbidity levels of the tigris river and indicates the need for pre-settling tanks especially in rainy seasons. fig.2. time plot for raw water turbidity. 100 300 500 700 900 0 200 400 600 800 1000 no. of observation 100 300 500 700 900 0 200 400 600 800 1000 ra w w at er tu rb id ity (n tu ) this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ faris hammoodi al-ani al-khwarizmi engineering journal, vol. 7, no. 2, pp 55 67 (2011) 58 clarified water clar no of ob s 0 60 120 180 240 300 360 420 480 540 600 660 720 780 840 900 <= 0 (0;10] (10;20] (20;30] (30;40] (40;50] (50;60] (60;70] (70;80] > 80 table 1, descriptive statistics for raw water turbidity. n min. max. mean std. variance skewnees kurtosis statistic statistic statistic statistic std.error statistic statistic statistic std.error statistic std.error turbidity (raw) valid (list wise) 890 890 10.00 1000.0 41.368 1.9950 59.518 3542.375 7.846 0.082 92.682 0.164 3.2. analysis of clarified water turbidity data clarified water turbidity is shown in figure 3, it is clear that turbidity level increases as the turbidity of raw water increased. from the cumulative frequency curve (figure 4) there are 290 days out of 895 the turbidity levels were below 10 ntu, this gives a probability success of (290/895  0.324) for the clarified water with turbidity levels below or equal to 10 ntu, as recommended by steel and mcghee (1979). however the probability of compliance with the plant design guarantee of 20 ntu is (771/895=0.861). table 2 lists the statistical description of the daily turbidity data of the clarified water. the mean value of the turbidity level was found to be 14 ntu with a standard deviation of 6.54 resulting in cv of 46.5%, this value is somewhat high as confirmed by the range, which is found to be 1.4 to 77 ntu. fig.3. time plot for clarified water turbidity. fig.4. cumulative frequencies for clarified water turbidity. 100 300 500 700 900 0 200 400 600 800 1000 no. of observation 10 30 50 70 0 20 40 60 80 cla rifi er tu rbi dit y( nt u) this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ faris hammoodi al-ani al-khwarizmi engineering journal, vol. 7, no. 2, pp 55 67 (2011) 59 filtered water filt no of ob s 0 62 124 186 248 310 372 434 496 558 620 682 744 806 868 930 <= 0 (0;.5] (.5;1] (1;1.5] (1.5;2] (2;2.5] (2.5;3] (3;3.5] (3.5;4] (4;4.5] (4.5;5] table 2, descriptive statistics for clarified water turbidity. n min. max. mean std. variance skewnees kurtosis statistic statistic statistic statistic std.error statistic statistic statistic std.error statistic std.error turbidity (clarified) valid (list wise) 895 895 1.40 77.00 14.059 0.2188 6.5446 42.832 1.765 0.082 9.781 0.163 3.3. analysis of filtered water turbidity data time plot for daily filtered water turbidity data is shown in figure 5. from figure 6 it can be seen that there is on the average about 100% compliance with the iraqi drinking water standards, which calls for 5 ntu. the mean value of the turbidity level of filtered water from table 3 was found to be 1.0588 ntu with a standard deviation of 0.56, resulting in cv of 52.9%. this value is somewhat high as confirmed by the range 0.2-4.5 ntu. this demonstrates that the performance of the filter has not been affected by the high raw water turbidity because the clarifiers have enough ability to treat raw water of high turbidity. according to the united state environmental protection agency (usepa) standard limits on drinking water which calls for a maximum of 2-day average of 5 ntu maximum turbidity level, figures 7 and 8 show a time plot and a cumulative frequency curve for the 2-day moving average and table 4 lists the statistics for a 2-day turbidity average. the mean of 2-day moving average is found to be 1.059 ntu with a standard deviation of 0.464. this gives cv 43.8%, with a range value of 0.3 to 3.68 ntu. it could be stated that there is100% compliance with this standard as far as turbidity quality is concerned and the filters operate perfectly and according to their design limitations. fig.5. time plot for filtered water turbidity. fig.6. cumulative frequencies for filtered water turbidity. 100 300 500 700 900 0 200 400 600 800 1000 no. of observation 0.5 1.5 2.5 3.5 4.5 0.0 1.0 2.0 3.0 4.0 5.0 filt er tu rbi dit y(n tu ) this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ faris hammoodi al-ani al-khwarizmi engineering journal, vol. 7, no. 2, pp 55 67 (2011) 60 table 3, descriptive statistics for filtered water turbidity. n min. max. mean std. variance skewnees kurtosis statistic statistic statistic statistic std.error statistic statistic statistic std.error statistic std.error turbidity (filt.) 896 0.20 4.50 1.0588 0.0189 0.5671 0.322 1.917 0.082 5.308 0.163 valid (list wise) 896 fig.7. time plot of 2-day moving average for filtered water turbidity. fig.8. cumulative frequency of 2-day moving average for filtered water turbidity. table 4, descriptive statistics of 2-day moving average for filtered water turbidity. n min. max. mean std. variance skewnees kurtosis statistic statistic statistic statistic statistic statistic statistic std.error statistic std.error (turb.filter.,2 ,2) 894 0.30 3.68 1.0592 0.4639 0.215 1.681 9.082 4.416 0.163 valid (list wise) 894 100 300 500 700 900 0 200 400 600 800 1000 no. of observation 0.50 1.50 2.50 3.50 0.00 1.00 2.00 3.00 4.00 fil ter tu rbi dit y( nt u) 2-day moving average 2-day moving average for filter turbidity filt_2 no o f o bs 0 60 120 180 240 300 360 420 480 540 600 660 720 780 840 900 <= 0 (0;.5] (.5;1] (1;1.5] (1.5;2] (2;2.5] (2.5;3] (3;3.5] (3.5;4] > 4 this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ faris hammoodi al-ani al-khwarizmi engineering journal, vol. 7, no. 2, pp 55 67 (2011) 61 30-day moving average for filtered water filt_30 no o f o bs 0 58 116 174 232 290 348 406 464 522 580 638 696 754 812 870 <= .6 (.6;.8] (.8;1.] (1;1.2] (1.2;1.4] (1.4;1.6] (1.6;1.8] (1.8;2.] > 2 according to the usepa standards the 30-day moving average (turbidity should be less than 1 ntu, figures 9 and 10 show a time plot and a cumulative frequency curve for the 30-day moving average. from these figures it can be seen that the probability of success for the filters is equal to 0.5023, and the compliance with this standard limit is not more than 50.23%. this means that there is violation average of this standard limit of about 49.77% in the day of the year. table 5 gives the statistical description of the 30-day moving average of turbidity for the filtered water. the annual average value of the turbidity of the filtered water is about1.054 ntu with a standard deviation of 0.279. this gives cv of 26.5% which is somewhat low as confirmed by the range, which is found to be 0.6 to 2 ntu. fig.9. time plot of 30-day moving average for filtered water turbidity. fig.10. cumulative frequency of 30-day moving average for filtered water turbidity. table 5, descriptive statistics of 30-day moving average for filtered water turbidity. n min. max. mean std. variance skewnees kurtosis statistic statistic statistic statistic statistic statistic statistic std.error statistic std.error (turb.filter.,30, 30) 866 0.60 2.01 1.0544 0.2795 0.078 1.099 0.083 1.134 0.166 valid (list wise) 866 100 300 500 700 900 0 200 400 600 800 1000 no. of observation 0.60 1.00 1.40 1.80 2.20 0.40 0.80 1.20 1.60 2.00 2.40 fil ter tu rbi dit y( nt u) 30-day moving average this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ faris hammoodi al-ani al-khwarizmi engineering journal, vol. 7, no. 2, pp 55 67 (2011) 62 3.4. analysis of supplied water turbidity data sometimes turbidity of the water supplied is slightly more than that of the filtered water as shown in figure 11 because the samples of filtered water were taken from clean filters that were washed and operated ideally. the unwashed filters provide filtered water with greater turbidity than the former ones. the mixing of filtered water coming from washed and unwashed filters before entering the treated water reservoir increase in supplied water turbidity. from the cumulative frequency graph (figure 12) there is about 98% compliance with the iraqi drinking water standards. the violation of this standard limit is in november-december and march-april. it was well known that november-december is the period of the rainy season, while march-april is the period of high river flow resulting from snow melting up in the tigris river catchment area, both periods contribute to turbidity. the mean value of the turbidity level of the supplied water from table 6 is 1.8 ntu with a standard deviation of 0.8 resulting in cv of 43.9%. this value is somewhat high as compared with the range, which is found to be 0.4 to 9.5 ntu. figures 13 and 14 show a time plot and a cumulative frequency curve for the 2-day moving average turbidity. based on usepa standard limits of drinking water it can be stated that there is 870/882  98.6% compliance with this standard as far as turbidity quality is concerned. this means that the average violation of this standard is of about 1.4%. table 7 lists the statistics for a 2-day turbidity average of the supplied water. the mean value is found to be 1.829 ntu, where there is 98.6% the compliance with 2-day moving average turbidity level as set by the epa. the cv for the 2-day moving average statistic is estimated to be about 26.45%, with an average ranging from 0.45 to 6 ntu, this is rather good according to this standard. fig.11. time plot for supplied water turbidity. fig.12. cumulative frequencies for supplied water turbidity. 100 300 500 700 900 0 200 400 600 800 1000 no. of observation 1.00 3.00 5.00 7.00 9.00 0.00 2.00 4.00 6.00 8.00 10.00 su pp lyt urb idi ty (nt u) supply water suppl no o f o bs 0 62 124 186 248 310 372 434 496 558 620 682 744 806 868 930 <= 0 (0;1] (1;2] (2;3] (3;4] (4;5] (5;6] (6;7] (7;8] (8;9] (9;10] > 10 this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ faris hammoodi al-ani al-khwarizmi engineering journal, vol. 7, no. 2, pp 55 67 (2011) 63 2-day moving average for supplied water supp_2 no o f o bs 0 59 118 177 236 295 354 413 472 531 590 649 708 767 826 885 <= 0 (0;.5] (.5;1] (1;1.5] (1.5;2] (2;2.5] (2.5;3] (3;3.5] (3.5;4] (4;4.5] (4.5;5] (5;5.5] (5.5;6] (6;6.5] > 6.5 table 6, descriptive statistics for supplied water turbidity. n min. max. mean std. variance skewnees kurtosis statistic statistic statistic statistic std.error statistic statistic statistic std.error statistic std.error turbidity (supply.) 884 0.40 9.50 1.8286 0.0270 0.8032 0.645 2.564 0.082 14.890 0.164 valid (list wise) 884 fig.13. time plot of 2-day moving average for supplied water turbidity. fig.14. time plot of 2-day moving average for supplied water turbidity. table 7, descriptive statistics of 2-day moving average for supplied water turbidity. n min. max. mean std. variance skewnees kurtosis statistic statistic statistic statistic statistic statistic statistic std.error statistic std.error (turb. supp..,2,2) 882 0.45 6.00 1.8294 0.7000 0.490 1.883 0.082 6.547 0.164 valid (list wise) 882 100 300 500 700 900 0 200 400 600 800 1000 no. of observation 1.00 3.00 5.00 0.00 2.00 4.00 6.00 su pp lyt urb idi ty (nt u) 2-day supply water this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ faris hammoodi al-ani al-khwarizmi engineering journal, vol. 7, no. 2, pp 55 67 (2011) 64 according to the usepa standard on drinking water quality, which calls for a monthly average of 1 ntu, it can be seen from figures 15 and 16 that compliance with this standard limit is not more than 1.4%. this means that there is a violation average of this standard limit reaching 98.6% of the days of year. table 8 gives the statistical description of 30-day moving average of the turbidity data. from this table, it can be seen that the annual average value of the turbidity is about 1.82 ntu with a standard deviation of 0.483. this gives cv of 26.45% which is somewhat low as compared with the range value which is 0.81 to 3.42 ntu. fig.15. time plot of 30-day moving average for supplied water. fig.16. cumulative frequency of 30-day moving average for supplied water turbidity. table 8, descriptive statistics of 30-day moving average for supplied water turbidity. n min. max. mean std. variance skewnees kurtosis statistic statistic statistic statistic statistic statistic statistic std.error statistic std.error (turb.supp.,30, 30) 854 0.81 3.42 1.8290 0.4839 0.234 1.057 0.084 1.318 0.167 valid (list wise) 854 100 300 500 700 900 0 200 400 600 800 1000 no. of observation 0.50 1.50 2.50 3.50 0.00 1.00 2.00 3.00 4.00 su pp lyt urb idi ty (nt u) 30-day supply water 30-day moving average for supplied water supp_30 no o f o bs 0 58 116 174 232 290 348 406 464 522 580 638 696 754 812 870 <= 1 (1;1.5] (1.5;2] (2;2.5] (2.5;3] (3;3.5] > 3.5 this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ faris hammoodi al-ani al-khwarizmi engineering journal, vol. 7, no. 2, pp 55 67 (2011) 65 3.5. correlation between parameters through the matrix of correlation between parameters (different turbidities) shown in table 9, the following can be noticed: 1. there is no significant relationship between the turbidity of raw water values with both the turbidity value of the clarified water, filtered water and the supplied water. their values are 4.8% 1.5% and 2.1% respectively. they are regarded as values even if they do not approach zero. 2. the significant relationship is noted between the turbidity of the supplied water with both the turbidity of the clarified and the filtered water represented by the values of 27.7% and 26.5% receptively. table 9, correlation matrix between the parameters. turbidity (raw) turbidity (clarifier) turbidity (filter) turbidity (supply) t ur bi di ty (r aw ) pearson correlation 1 0.048 -0.015 0.021 sig. (2-tailed) 0.15 0.663 0.523 no. 890 890 890 884 t ur bi di ty (c la ri fi er ) pearson correlation 0.048 1.0 0.230* 0.277* sig. (2-tailed) 0.15 0.000 0.000 no. 890 895 895 884 t ur bi di ty (f ilt er ) pearson correlation -0.015 0.23* 1.0 0.265* sig. (2-tailed) 0.663 0.000 0.000 no. 890 895 896 884 t ur bi di ty (s up pl y) pearson correlation 0.021 0.277 0.265* 1.0 sig. (2-tailed) 0.523 0.000 0.000 no. 884 884 884 884 * correlation is significant at the 0.01 level (2-tailed). 4. conclusions daily data for turbidity of raw, clarified, filtered and supplied water of sherq dijjla water treatment plant were analysed to the assess the performance of the plant. the conclusions are as follows: 1. there is a wide variation in turbidity levels of the raw water of tigris river at the intake. turbidity levels fluctuate between 10 and 1000 ntu with a mean value of 41 ntu and a coefficient of variation of 1.44. high water turbidity levels were encountered during the rainy season covering the time between november, december, january and february of each year this indicates the need for presetting tanks. 2. turbidity values of the clarified water vary between 1.4 and 77 ntu. on 290 days out of 895 days the turbidity level was below 10 ntu. this gave a probability of compliance of 32.4% according to steel and mcghee (1979) and 771 days out of 895 turbidity level was below 20 ntu, where the probability of compliance was 86% according to design guarantee of treatment plant. 3. turbidity data of the filtered water from sharq dijjla water treatment plant was completely in compliance with iraqi and who standards with mean turbidity level of 1.05 ntu. this demonstrates that the performance of the filter has not been affected by the high raw turbidity because the clarifiers work efficiently. 4. for 2-day moving average, turbidity data of the filtered water was completely in compliance with usepa standard because the values were less than 5 ntu. for 30-day moving average of 1 ntu turbidity value of the filtered water, it was found that filters this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ faris hammoodi al-ani al-khwarizmi engineering journal, vol. 7, no. 2, pp 55 67 (2011) 66 operation violated the usepa standard by 49.77%. 5. turbidity of the supplied water in the treated water reservoir was greater than the filtered water turbidity for operational reasons. 6. supplied water turbidity showed about 98% compliance with the iraqi drinking water standard, with mean value of 1.8 ntu. on the basis of 2-day water turbidity, the turbidity of the supplied water was 98.6% in compliance with the usepa standard. while for the 30day moving average turbidity, the supplied water violated usepa standard by 98.6%. 5. recommendations for operation of treatment plant 1. systematic maintenance of the different treatment units. 2. operating water treatment plant according to the scientific conventional method and operation manual in terms of dosing chemicals, de-sludging and backwashing process is highly recommended. 3. continuing monitoring different units to get high water quality. 6. references [1] buckley, c.b., 1984,”potable water coast effective treatment and control”, j. of inst.water eng. sci., vol.38, no.3, pp. 259271. [2] cheremisinoff, n.p., 2002, “handbook of water and wastewater technologies”, butterworth-heinemann publications. [3] letterman, r.d., 1999, “water quality and treatmenta handbook of community water supplies”, mcgraw-hill, (5th edition). [4] paterson candy international ltd., 1987, “operating and maintenance instructions manual”, parts 1&3 for baghdad water supply administration. [5] raju, b., 1995,”water supply and wastewater engineering”, tata mcgrawhill, new delhi. [6] rammalley, b.l., lawler, d.f., wright, w.c., and o melia, c.r., 1981,”integral analysis of water plant performance”, j. of env. eng. div., no. ee3. [7] steel, e.w., and mcghee, t.j., 1979,”water supply and sewage”, mcgraw-hill. [8] twort, a.c, ratnayaka, d.d., and brandt, m.j., 2009, “ water supply”, butterworthheinemann publications, binne black & veatch, 6th edition. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ 67 ، صفحة2، العدد 7مجلة الخوارزمي الھندسیة المجلد فارس حمودي محمد 55 )2011( 67 تقیم اداء محطة ماء شرق دجلة واصل كاظم فارس حمودي محمد عة التكنولوجیةالجام/ واإلنشاءاتقسم ھندسة البناء الخالصة ن من الھدف إن رة م ورة للفت ة العك ة ٢٠٠١-٤-١ھذه الدراسة ھو تقیم اداء محطة تصفیة ماء شرق دجلة في ازال ات ٢٠٠٤-٤-٣١ولغای ل قیاس م تحلی ت ین بینت نتائج الدراسة ان ھناك ا. العكورة للمیاه الخام، المیاه المرسبة، المیاه المرشحة، والمیاه المجھزة ت ب ام تراوح اء الخ ختالف كبیر في درجة العكورة للم ورة ٧٧-١.٤قیم العكورة للمیاه المرسبة كانت . وحدة قیاس العكورة ٤١,٣وبمعدل ١٠٠٠-١ ة عك ى قیم اد عل میمیة ( ٢٠و ١٠وحدة و باالعتم رى ) التص ن دارھا ول مق بة قب ت نس والي % ٨٦و% ٣٢.٤ان القراءات اعط ى الت ورة ل . عل ا العك ین ام ت ب حة فتراوح اه المرش ع ٤.٥-٠.٢لمی ا م ق كلی ي تتواف دة والت وح ر -٢وبالمقارنة مع مواصفة منظمة حمایة البیئة االمریكیة وباالعتماد على تحلیل . ة العالمیةمواصفة القیاسبة العراقیة ومواصفة منظمة الصح دل متغی وم مع ی ین .على التوالي% ٤٥و%١٠٠وجد ان الفالتر تعمل بنسبة قبول قدرھا ) وحدة ١(یوم معدل متغیر -٣٠و) وحدة ٥( ورة ب ت العك زة تراوح واما المیاه المجھ ن وحدة وھي اع ٩.٥-٠.٤ ر م ولة اكب ر مغس لى من عكورة المیاه الراشحة وھذا نتیجة للخلط الحاصل بین میاه جمیع المرشحات كون العكورة للمرشحات الغی ة، . المرشحات المغسولة اضافة للترسبات الطینیة داخل الخزان االرضي للمیاه المجھزة بة العراقی فات القیاس ى المواص اد عل رك، -٢وباالعتم دل متح وم مع ی . ضمن الحدود المسموح بھا على التوالي% ٩٨.٦، %٩٨.٦، %٩٨المجھزة كانت یوم معدل متحرك فأن المیاه -٣٠و this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ 86 تأثير انقطع بانهيسرعهى دقت األبعاد وطبيعت األسطح انًثقبت ** حايذ صانح يهذي*يصطفى احًذ رجب ثؼمٛثخ–اٌّؼٙذ اٌزمٕٟ / لغُ ا١ٌّىب١ٔه* عبِؼخ ثغذاد/ و١ٍخ إٌٙذعخ اٌخٛاسصِٟ/ لغُ ٕ٘ذعخ ػ١ٍّبد اٌزظ١ٕغ ** e-mail: mostafaalnajar@yahoo.com* e-mail: al_sarraf1@hotmail.com** (received 17 april 2011; accepted 14 november 2011) انخالصت ٠بن ِٓ خالي عٙبص ٌٗ ِٛاطفبد ِخزٍفخ ٌذساعخ ػ١ٍّخ رضم١ت ٌّبدح ِغزخذِخ فٟ اٌّغبالد اٌظٕبػ١خ ٚاٌؼ١ٍّخ -عزخذَ فٟ ٘زا اٌجؾش ١ٌضس ا١ٌٕذ١َِٛأ اٌخظبئض اٌّئصشح فٟ ػ١ٍّخ اٌزضم١ت ٌٍظٍت اٌخطٛاد اٌزطج١م١خ ٌٍزؾمك ِِٓٓ ٕ٘ب وبٔذ اٌذساعخ فٟ ٘زا اٌجؾش ِٓ خالي ، ِضً اٌظٍت إٌّغ١ٕضٞ اٌظٍذ رؾذس ػ١ٍّخ اٌزضم١ت ٔز١غخ اِزظبص اٌّبدح ٌغضء ِٓ أشؼخ ا١ٌٍضس اٌغبلطخ ػ١ٍٙب ٟٚ٘ ِؾظٍخ رذاخً خٛاص ا١ٌٍضس ٚاٌّبدح . ٠ضسيإٌّغ١ٕضٞ اٌظٍذ ثبي أٚضؾذ ٔزبئظ اٌجؾش اْ ص٠بدح طبلخ شؼبع ا١ٌٍضس ػٓ ل١ّخ ِؼ١ٕخ رئدٞ اٌٝ ص٠بدح لطش ٚػّك اٌضمت إٌّزظ ٚرم١ًٍ ِخشٚط١زٗ، . ٚششٚط رجئس االشؼخ . ثبإلضبفخ اٌٝ ص٠بدح فٟ ِؼذي اإلصاٌخ ِٚمذاس اٌخشٛٔخ .عٍجخ اٌضمت، طبلخ ا١ٌٍضس، اٌزجئس، شؼبع ا١ٌٍضس، اٌظٍت إٌّغ١ٕضٞ اٌظٍذ،اٌزضم١ت ثب١ٌٍضس:انكهًاث انًفتاحيت انًقذيت .1 unconventional machiningػ١ٍّبد اٌمطغ اٌالرم١ٍذ٠خ processes ٍٝػ١ٍّبد اٌمطغ اٌزٟ ال ٠ؼزّذ اٌزشغ١ً ػ ٟ٘ٚ طالدح أداح اٌمطغ وّب ٘ٛ ِؼشٚف ثبٌطشق اٌزم١ٍذ٠خ ثً ٠ؼزّذ ػٍٝ ِزغ١شاد أخشٜ ٠ّىٓ اٌغ١طشح ػ١ٍٙب ِضً اٌز١بس، اٌفٌٛز١خ، ،اٌضغظ (abrasives)اٌزثزثبد، عشػخ األعضاء اٌؾبوخ اٌؼٛاًِ اٌزبو١ٍخ (hydraulic pressure)ا١ٌٙذس١ٌٚىٟ (corrosive agent) ٚاٌّٛاد اٌّزؤ٠ٕخ(materialsionized ) ٚغ١ش٘ب ٚرّزبص ٘زٖ اٌطشق ثبِىب١ٔخ اٌؾظٛي ػٍٝ دلخ ػب١ٌخ ِب٠ىش١ِٚزش (0.5 – 0.25)ٚٔؼِٛخ عطؾ١خ ع١ذح رظً اٌٝ ٚرزضّٓ ٘زٖ اٌطشق أٔٛاع ِزؼذدح ثبالػزّبد ػٍٝ ٔٛع اٌطبلخ رّـ١ضد ػ١ٍّبد اٌزضم١ت . [1,2]اٌّغزخذِخ ٚوّب ِج١ٓ أدٔبٖ ػذَ اٌؾبعخ اٌٝ : ثبعزخذاَ شؼبع ا١ٌٍضس ثؼذح ١ِّضاد ِٕٙب ؽظٛي أٞ رالِظ ِجبشش ِغ اٌّشغٌٛخ، اِىب١ٔخ اٌزضم١ت اٌذل١ك ٚثضٚا٠ب ِبئٍخ ٚثذلخ ػب١ٌخ ٔز١غخ رشو١ض األشؼخ ثشىً ِغ١طش ػ١ٍٗ ، اِىب١ٔخ رضم١ت اٌّٛاد اٌظٍذح ٚاٌٙشخ ٚاٌمبثٍخ ٌٍىغش ثذْٚ ٔؾبرخ (chip) الْ اٌّٛاد اٌّضاٌخ رىْٛ ػٍٝ ١٘ئخ ثخبس ِٚٛاد ِٕظٙشح اٌىٍفخ اٌؼب١ٌخ، ِؾذٚد٠خ :اال اْ ِٓ عٍج١بد ٘زٖ اٌزم١ٕخ ٟ٘. [4,3] خشٛٔخ اٌغطؼ إٌّزظ ،( 13ٍُِ)أػّبق اٌزضم١ت اٌزٟ ال رزغبٚص ٚػذَ أزظبَ اٌشىً إٌٙذعٟ ٌٗ ػٕذ اإلخفبق فٟ اعزخذاَ اٌظشٚف اٌّضٍٝ ٌٍزضم١ت ، ِخشٚط١خ اٌضمت إٌّزظ ػٕذ اإلخفبق ثبخز١بس ّٔظ ٌمذ وبْ االػزمبد اٌغبئذ فٟ اٌجذا٠خ ثؤْ اٌّبدح . [5]ح ٚشىً إٌجض اٌّضاٌخ ػٕذ اٌزضم١ت ثب١ٌٍضس ٟ٘ ثؾبٌخ ثخبس ٠ٕزظ ِٓ اٌزغخ١ٓ اٌغش٠غ ٌٍّبدح اٌٝ ؽشاسح أوجش ِٓ دسعخ رجخش٘ب ػٕذ رغ١ٍظ وضبفخ لذسح ١ٌضس٠خ ػب١ٌخ، ثؼذ رٌه فمذ أٚضؾذ اٌجؾٛس ٚاٌذساعبد ، ثؤْ طبلخ ا١ٌٍضس غ١ش وبف١خ ٌزجخ١ش و١ّخ اٌّبدح اٌّضاٌخ، [7,8] ٚث١ٕذ ثؤْ ِب أص٠ً ِٓ اٌّبدح وبْ ث١ٙئخ ثخبس ِٚبدح ِٕظٙشح ٚرش١ش ثؼض . (%10)ِزطب٠شح ال ٠شىً اٌجخبس ف١ٙب اال ٔغجخ ، اٌٝ اْ لذسح ا١ٌٍضس رزؾٛي اٌٝ طبلخ ؽشاس٠خ [10,9]اٌذساعبد رشفغ ِٓ ؽشاسح اٌجمؼخ اٌزٟ رزشوض ف١ٙب االشؼخ اٌٝ دسعخ اٌزجخش ٚفٟ ٔفظ اٌٛلذ فؤْ االٔزشبس اٌؾشاسٞ ٠جذأ فٟ رٍه إٌّطمخ، ٚلجً ثذأ ػ١ٍّخ اٌغ١ٍبْ ٠جذأ اٌغطؼ ثبالٔظٙبس ٌىٓ إٌّٛ اٌغش٠غ فٟ دسعخ اٌؾشاسح عٛف ٌٓ ٠غّؼ ثٛلذ وبفٟ ٌؾذٚس ص٠بدح فٟ اٌزٚثبْ ٚٔز١غخ الِزظبص طبلخ اضبف١خ رؾذس ػ١ٍّخ اٌغ١ٍبْ صُ ٚرؼزّذ ٔغجخ اٌّبدح إٌّظٙشح اٌّزطب٠شح ػٍٝ وضبفخ لذسح . اٌزجخش ا١ٌٍضس ؽ١ش رمً ػٕذ ص٠بدح وضبفخ اٌمذسح، ٠ٚزغُ شؼبع ا١ٌٍضس ثخظبئض ِّٙخ ٔز١غخ رؤص١شٖ فٟ اٌّبدح اٌّّزظخ ٌٗ، ؽ١ش رغجت رٍه اٌزؤص١شاد رؾٛالد طٛس٠خ فٟ اٌّبدح، ٚفٟ أؽ١بْ أخشٜ ٠ؾذس وّب أٚضؾذ . [11,8]رغخ١ٓ ٌٍّبدح دْٚ أٞ رؾٛي طٛسٞ ٌٙب اْ ػ١ٍّخ اٌزفبػً اٌزٟ رؾظً ِب ث١ٓ [12]اٌجؾٛس ٚاٌذساعبد صِٓ ٔجضخ : شؼبع ا١ٌٍضس ٚاٌّبدح اٌّشاد رشغ١ٍٙب رؼزّذ ػٍٝ ا١ٌٍضس، وضبفخ اٌمذسح، لطش شؼبع ا١ٌٍضس، اِزظبط١خ اٌّبدح ألشؼخ . ا١ٌٍضس، االٔزشبس٠خ اٌؾشاس٠خ، ثبإلضبفخ اٌٝ طج١ؼخ عطؼ اٌّبدح انهذف ين انبحث .2 اْ اٌذلخ اٌؼب١ٌخ فٟ اإلٔزبط ٚاٌزم١ًٍ ِٓ ٔغجخ اٌخطؤ، اضبفخ اٌٝ رفبدٞ اٌزٍف، عؼً ِٓ اعزخذاَ طشق اٌمطغ اٌالرم١ٍذ٠خ فٟ ِغبي اٌظٕبػخ راد عذٜٚ الزظبد٠خ، ؽ١ش أطجؼ ثبإلِىبْ اٌؾظٛي ِٓ ،ػٍٝ ٔٛػ١خ ٚأٙبء عطؾٟ عذ٠ذ ٌٍّٕزظ اٌّشغً ثٙزٖ اٌزم١ٕخ al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 8, no. 1, pp 86 -91 (2012) mailto:mostafaalnajar@yahoo.com mailto:al_sarraf1@hotmail.com (2012) 91-86، انصفحت 1، انعذد 8 يجهت انخىارزيً انهنذسيت، انًجهذ يصطفى احًذ رجب 87 ٕ٘ب عبءد فىشح اٌجؾش ِٚٓ خالي دساعخ طج١ؼخ األعطؼ ٚدلخ . األثؼبد إٌّزغخ ثؼ١ٍّخ اٌزضم١ت ثبعزخذاَ شؼبع ا١ٌٍضس اإلجراء انعًهً .3 ق اٌمطغ اةأعش٠ذ ػ١ٍّخ اٌزضم١ت ثٛاؽذح ِٓ طشق ِٓ طش اٌالرم١ٍذ٠خ ٟٚ٘ اٌزضم١ت ثشؼبع ا١ٌٍضس ػٍٝ ػ١ٕبد ِٓ اٌظٍت ، ٚاٌّٛضؼ (manganese hard steel)إٌّغ١ٕضٞ اٌظٍذ (. 1)رشو١جٗ اٌى١ّ١بٚٞ ثبٌغذٚي ٚلذ رُ رٕبٚي اٌطش٠مخ ِٓ ؽ١ش خشٛٔخ اٌغطؼ إٌّزظ، ٚدلخ فٟ اٌجذا٠خ رُ ،األثؼبد ٌٍؼ١ٕبد، ثبإلضبفخ ِؼذي اصاٌخ اٌّؼذْ ٍُِ (20*20*60)رؾض١ش اٌؼ١ٕبد إٌٙبئ١خ، ثم١بع١ٓ، األٚي ٍُِ، ؽ١ش اعزخذِذ اٌؼ١ٕبد األٌٚٝ (5*40*120)ٚاٌضبٟٔ اِب . ٌذساعخ رؤص١ش ػّك اٌزشغ١ً، ٚاٌضب١ٔخ ٌذساعخ ثبلٟ اٌّزغ١شاد ٠بن، ١ٌضس ا١ٌٕٛٔذ٠َٛ ػِٕٓظِٛخ ا١ٌٍضس اٌّغزخذِخ فٟٙ ػجبسح ( 8)ِب٠ىشٚ صب١ٔخ، ٚاٌطبلخ اٌّغزخذِخ (300)صِٓ إٌجضخ ٌٙب عُ، ٚلطش (15.5)لض١ت ١ٌضس ثطٛي : رزضّٓ إٌّظِٛخ. عٛي ( linear flash lamp)عُ، ِٚظجبػ ِٚضٟ خطٟ (0.9) ، %(100)ػذد اصٕبْ، اضبفخ اٌٝ ِشآح خٍف١خ ِمؼشح، أؼىبعبرٙب اِب وضبفخ لذسح شؼبع ا١ٌٍضس فمذ %. (30)رٙب ِٞٚشآح أِب١ِخ، أؼىبط [[3(:1)رُ ؽغبثٙب ِٓ خالي اٌّؼبدٌخ i= e/ ( .f 2 .  2 .j) …(1) :ؽ١ش اْ i =وضبفخ لذسح شؼبع ا١ٌٍضس e = طبلخ ا١ٌٍضس  = 3.14= إٌغجخ اٌضبثزخ f =اٌجؼذ اٌجئسٞ ٌٍؼذعخ ( cm)  = أفشاع١خ اٌشؼبع ( rad) j = صِٓ ٔجضخ ا١ٌٍضس(sec) -1-جذول .انتركيب انكيًياوي نهصهب انًستخذو فً انبحث c si mn p s mo cr feانعنصر rem 1.2 0.2 0.046 0.007 18 0.03 0.4% إٌغجخ ٚلذ أعش٠ذ ػذح ِؾبٚالد ٌّؼشفخ وضبفخ لذسح ا١ٌٍضس ػٕذ ل١ُ :(2)ِخزٍفخ ٌٍجؼذ اٌجئسٞ ٌٍؼذعخ وّب ِٛضؾخ ثبٌغذٚي -2-جذول 0 كثافت انقذرة عنذ قيى يختهفت نهبعذ انبؤري نهعذست 20 10 8 5 (سى)انبعذ انبؤري نهعذست 5* 10-6* 10 2* 10-3* 10 4* 10-3* 10 9.8*10-8* 10 (سى/واط)كثافت قذرة انهيسر ( 2)أِب أفشاع١خ شؼبع ا١ٌٍضس ف١ّىٓ ؽغبثٙب ِٓ خالي اٌّؼبدٌخ ]3[. = (d2-d1)/2l …(2) :ؽ١ش اْ d1 = لطش اٌؾضِخ ػٕذ اٌّغبفخx1 d2 = لطش اٌؾضِخ ػٕذ اٌّغبفخx2 l = ٓاٌفشق ث١ٓ اٌّغبفز١ 10)ؽ١ش ٚعذ اْ أفشاع١خ األشؼخ ٌٍغٙبص -3 *2 )rad ِٓٚص ، 10)ٔجضخ ا١ٌٍضس -3 ِب٠ىشٚصب١ٔخ، ٚلذ رُ ل١بط لطش اٌضمت (1.06* ثؾ١ش رٛضغ (optical microscope)ثبعزخذاَ ِغٙش ضٛئٟ اٌؼ١ٕخ ػٍٝ لبػذح اٌّغٙش ٠ٚزغ١ش اسرفبػٙب ؽزٝ ٠زُ اٌؾظٛي ػٍٝ أٚضؼ طٛسح ٌٍغطؼ صُ ٠ٛضغ ِئشش اٌؼذعخ اٌؼ١ٕ١خ ػٍٝ ؽبفخ اٌضمت، صُ ٠ؾشن اٌٝ اٌؾبفخ اٌّمبثٍخ ٠ٚؾغت اٌفشق ث١ٓ اٌمشاءر١ٓ اِب ػّك اٌضمت فمذ رُ . ٚرؼبد اٌؼ١ٍّخ صالس ِشاد، ٠ٚئخز ِؼذٌٙب ل١بعٗ ثٕفظ اٌغٙبص ٚثٕفظ اٌطش٠مخ ؽ١ش ٠ئخز اٌفشق ث١ٓ لشاءر١ٓ، األٌٚٝ ألٚضؼ طٛسح ٌٍغطؼ، ٚاٌضب١ٔخ ألٚضؼ طٛسح ػٓ (hole taper)ث١ّٕب رمبط ِخشٚط١خ اٌضمت . ٌمؼش اٌضمت .طش٠ك ل١بط لطشٞ اٌضمت ػٕذ اٌغطؼ ٚاٌمؼش ٚاٌؼّك داخً اٌّبدح (لطش اٌضمت ػٕذ اٌمؼش– لطش اٌضمت ػٕذ اٌغطؼ )= عٍجخ اٌضمت ( اٌضمتػّك)* 2 ... (3) أصٕبء رغ١ٍظ شؼبع ا١ٌٍضس ػٍٝ اٌغطؼ اٌّشاد رضم١جٗ ، فؤْ " إٌّطمخ اٌّزؤصشح ثشؼبع ا١ٌٍضس ٟ٘ ػجبسح ػٓ لطش اٌضمت ِضبفب . ا١ٌٗ ِٕطمخ اٌزؤص١ش اٌؾشاسٞ ؽٛي اٌضمت فٟ ٘زا اٌجؾش رُ رغخ١ٓ وً ػ١ٕخ ػٍٝ ؽذح ِٚٓ صُ اعشاء صُ ل١بط ِمذاس اٌجٍٝ ػٍٝ أعبط ل١بط ػّك اٌزمؼش ، االخزجبس ػ١ٍٙب (crater wear )ػٍٝ اػزجبس اْ ( ٍُِ(0.12) ٌغطؼ األداح رغبٚص ٘زا اٌؼّك ٠ئدٞ اٌٝ ؽذٚس ضؼف فٟ ِزبٔخ اٌؾذ اٌمبطغ (2012 )91-86، انصفحت 1، انعذد 8 يجهت انخىارزيً انهنذسيت، انًجهذ يصطفى احًذ رجب 9088 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0 0.4 0.8 1.2 1.6 2 2.4 energy (joule) h o le d ep th ( m m ) hole depth mm hole diameter mm ِّب ٠ئدٞ اٌٝ ا١ٙٔبس وبًِ ٌٍؾذ اٌمبطغ ِّب ٠ئصش ػٍٝ اٌم١بط ؽ١ش ٚضغ عطؼ أداح اٌمطغ رؾذ ػذعخ ١ِىشٚعىٛة ]10[ ٚرُ اخز١بس أٞ ِٕطمخ ِٓ اٌغطؼ خبسط " دل١مب"ِمغُ رمغ١ّب good)" ِٕطمخ اٌزّبط ثؾ١ش رىْٛ اٌشإ٠خ ٚاضؾخ عذا focusing) ٍٝثؼذ رٌه ٠زُ رؾش٠ه اٌؼذعخ ثبرغبٖ ألظٝ رمؼش ػ عطؼ اٌزّبط ِٚٓ صُ رُ ل١بط اٌّغبفخ اٌزٟ ؽشوذ ثٙب اٌؼذعخ فزشح دٚ٘زٖ اٌّغبفخ رّضً ػّك ألظٝ رمؼش ٠ٚزُ اػبدح اٌؼ١ٍّخ ثغ .رضم١ت ِمذاس٘ب دل١مخ ٚاؽذح أِب ل١بط اٌخشٛٔخ اٌغطؾ١خ فمذ رُ اعزخذاَ عٙبص ٠ّىٓ ِٓ enlarged tracingخالٌٗ اٌؾظٛي ػٍٝ سعُ اعزٕغبخٟ ِىجش ٌخشٛٔخ اٌغطؼ ٚرغّٝ ٘زٖ اٌشعَٛ ثغبٔج١خ اٌغطؼ (( (surface profile) ؽ١ش ٠ؼًّ ٘زا اٌغٙبص ػٍٝ رىج١ش اٌؾشوخ أصٕبء ِغؾٙب ٌٍغطؼ، وّب ٠ّٚىٓ (stylus)اٌؼّٛد٠خ ٌإلثشح ٌٍغٙبص ثبإلضبفخ اٌٝ رغغ١ً اٌّغزّش ٌغبٔج١خ اٌغطؼ ػٍٝ شش٠ظ .ٚسلٟ اػطبء لشاءح ِجبششح ٌٍّزٛعظ اٌؾغبثٟ ٌخشٛٔخ اٌغطؼ وانًناقشت اننتائج .4 انتثقيب بأشعت انهيسر تأثير طاقت انهيسر .1.4 لطش ،رئصش طبلخ أشؼخ ا١ٌٍضس ػٍٝ وً ِٓ ػّك اٌضمت ِخشٚط١خ اٌضمت، ؽ١ش ٠ضداد ػّك اٌضمت ِغ ص٠بدح طبلخ ،اٌضمت ا١ٌٍضس، الْ ص٠بدح اٌطبلخ اٌّّزظخ ِٓ لجً اٌّبدح ٠ؼٕٟ ص٠بدح دسعخ ؽشاسرٙب ٚثبٌزبٌٟ ص٠بدح و١ّخ اٌّٛاد إٌّظٙشح ٚاٌّضاٌخ ثفؼً الْ رفبػً أشؼخ ا١ٌٍضس ِغ اٌّبدح ٠ؼٕٟ .ضغظ اٌجخبس اٌّزٌٛذ اِزظبص اٌّبدح ٌزٍه األشؼخ، ٚاْ أػٍٝ اِزظبص ٌٍطبلخ ٠ؾذس (.1شىً )ػٕذ اٌغطؼ ٠ٚزٕبلض ِغ ص٠بدح اٌجؼذ ػٕٗ وّب ٠ٚضداد لطش اٌضمت ِغ ص٠بدح طبلخ ا١ٌٍضس ٔز١غخ ص٠بدح لطش ؽضِخ األشؼخ ِغ ص٠بدح اٌطبلخ ثغجت ص٠بدح اٌطبلخ اٌّّزظخ ٚاٌزٟ رئدٞ اٌٝ ص٠بدح فٟ اٌؾشاسح اٌّزٌٛذح ٚرٛص٠ؼٙب ثبالرغبٖ اٌؼشضٟ (.1شىً ) . تأثير طاقت انهيسر عهى كم ين عًق وقطر انثقب-1-شكم ث١ّٕب رمً ِخشٚط١خ اٌضمت ِغ ص٠بدح طبلخ ا١ٌٍضس ثغجت اٌطبلخ اٌؼب١ٌخ اٌزٟ ٠ّىٕٙب ر١ٌٛذ ضغظ ػبٌٟ ٠ّىٓ ِٓ خالٌٗ اصاٌخ اٌّبدح ثشىً أوضش ٚفٟ اٌٛلذ ٔفغٗ رّٕغ ِٓ اٌزظبق اٌمطشاد إٌّظٙشح (.2شىً )ػٍٝ عذساْ اٌضمت ٚثبٌزبٌٟ رذفؼٙب اٌٝ اٌخبسط 0 10 20 30 40 50 60 70 80 90 100 0 0.4 0.8 1.2 1.6 2 2.4 energy (juole) h o lle t ap er ( d eg re e) . تأثير طاقت انهيسر عهى يخروطيت انثقب-2-شكم (2012 )91-86، انصفحت 1، انعذد 8 يجهت انخىارزيً انهنذسيت، انًجهذ يصطفى احًذ رجب 9089 0 0.5 1 1.5 2 2.5 0 1 2 3 4 5 6 7 laser power dens. (w/cm2) h o le d ep th ( m m ) تأثير كثافت قذرة انهيسر .2.4 ٠ضداد ػّك اٌضمت ِغ ص٠بدح وضبفخ لذسح ا١ٌٍضس ثغجت ص٠بدح اٌّزٌٛذ فٟ اٌضمت، ؽ١ش اْ رٌه ٠ئدٞ اٌٝ ص٠بدح اٌشؼبعضغظ و١ّخ اٌّٛاد اٌّضاٌخ ػٍٝ ١٘ئخ لطشاد عبئٍخ، ٌىٓ ػّك اٌضمت ٠جذأ ثبٌٕمظبْ ػٕذ ص٠بدح وضبفخ اٌمذسح، ٚاٌغجت فٟ رٌه ٘ٛ اْ و١ّخ اٌّٛاد اٌّزجخشح عٛف رىْٛ وج١شح ثؾ١ش رؼًّ ػٍٝ ؽغت ٚ اِزظبص أشؼخ ا١ٌٍضس ِٓ اٌٛطٛي اٌٝ اٌّبدح ٚثبٌزبٌٟ رمً اٌطبلخ اٌزٟ رظً اٌٝ اٌّبدح، ٚ٘زا ٠ئدٞ اٌٝ ٔمظبْ فٟ اٌطبلخ اٌٛاطٍخ (. 3شىً )اٌٝ اٌّبدح ِٚٓ صُ إٌمظبْ فٟ ػّك اٌضمت . تأثير كثافت انقذرة عهى عًق انثقب-3-شكم تأثير انفراجيت أشعت انهيسر عهى أبعاد انثقب .3.4 ص٠بدح )٠ضداد ػّك اٌضمت ِغ ٔمظبْ أفشاع١خ أشؼخ ا١ٌٍضس ٌٚىٓ ػٍٝ ؽغبة ٔمظبْ لطش اٌضمت (رشو١ض أشؼخ ا١ٌٍضس ٚاٌغجت فٟ رٌه ٠ؼٛد اٌٝ ٔمظبْ ِغبؽخ ِٕطمخ اٌزجئس ِغ .[4](:8) ٔمظبْ أفشاع١خ األشؼخ ؽغت اٌؼاللخ s=f. …(8) : ؽ١ش اْ s =ِغبؽخ ِٕطمخ اٌزجئس. f =اٌجؼذ اٌجئسٞ ٌٍؼذعخ.  =أفشاع١خ أشؼخ ا١ٌٍضس . ٚ٘زا ٠ٕزظ ػٕٗ ٔمظبْ فٟ لطش اٌضمت ِغ ص٠بدح اٌؼّك الْ وضبفخ (. 4شىً )لذسح ا١ٌٍضس رىْٛ ػب١ٌخ فٟ ٘زٖ اٌؾبٌخ 0 0.5 1 1.5 2 2.5 0 1 2 3 4 5 6 7 beam divergance ( mrad) h o le d im e n s io n ( m m ) depth mm diameter mm . تأثير انفراجيت اشعت انهيسر عهى ابعاد انثقب-4-شكم (2012 )91-86، انصفحت 1، انعذد 8 يجهت انخىارزيً انهنذسيت، انًجهذ يصطفى احًذ رجب 9090 رغزخذَ طش٠مخ اٌزضم١ت ثب١ٌٍضس ٚثشىً ػبَ ٌٍضمٛة اٌذل١مخ ٚاٌزٟ ٠ظؼت رضم١جٙب ثبٌطشق اٌزم١ٍذ٠خ، وّب ٠الؽع أصٕبء اٌزضم١ت ثب١ٌٍضس ظٙٛس دٚائش ِزؾذح اٌّشوض ؽٛي اٌضمت ثغجت اخزالف ِؼذي ٠الؽع أ٠ضب ضؼف ِمبِٚخ اٌزآوً . ٚعشػخ اٌزجش٠ذ ٌزٍه إٌّبطك ٌٍغطٛػ اٌّضمجخ ثب١ٌٍضس ثغجت اٌزؾٛي أٌطٛسٞ ٌٍّؼذْ فٟ اٌٙٛاء، ِٚٓ اٌغذ٠ش ثبٌزوش اْ . ٔز١غخ اٌؾشاسح اٌؼب١ٌخ اٌّزٌٛذح ػٍٝ اٌغطؼ أشؼخ ا١ٌٍضس ػٕذِب رىْٛ ثشذح ػب١ٌخ، فؤْ اٌّٛاد اٌّضاٌخ رزطب٠ش ِٓ اٌضمت ِىٛٔخ ثالصِب رؼًّ ػٍٝ رشزذ أشؼخ ا١ٌٍضس ػٓ اٌّؼذْ، shock)ٚثبٌزبٌٟ ٠زٌٛذ ضغظ ػٍٝ اٌغطؼ ث١ٙئخ طذِخ ِٛع١خ wave) رؾذس ثؼض اٌزشممبد(cracks.) االستنتاجاث .5 ٠ضداد ػّك اٌضمت اٌّشغً ثؤشؼخ ا١ٌٍضس ِغ ص٠بدح طبلخ األشؼخ -1 ثغجت اٌؾشاسح اٌؼب١ٌخ ٔز١غخ اٌطبلخ اٌّّزظخ، ِّب ٠ئدٞ اٌٝ ص٠بدح فٟ و١ّخ اٌّٛاد إٌّظٙشح ٚ اٌّضاٌخ ثفؼً ضغظ اٌجخبس . اٌّزٌٛذ ص٠بدح لطش اٌضمت اٌّشغً ثؤشؼخ ا١ٌٍضس ِغ ص٠بدح طبلخ األشؼخ -2 ٔز١غخ وجش لطش ؽضِخ ا١ٌٍضس ٚثبٌزبٌٟ اسرفبع و١ّخ اٌؾشاسح . اٌّزٌٛذح ٚأزشبس٘ب ثبالرغبٖ اٌؼشضٟ ٔمظبْ ِخشٚط١خ اٌضمت اٌّشغً ثؤشؼخ ا١ٌٍضس ِغ ص٠بدح طبلخ -3 . األشؼخ ٔز١غخ اٌض٠بدح فٟ ِؼذي اٌّٛاد اٌّضاٌخ ِٓ اٌغذساْ اؽ١بٔب لذ رؼبق ػ١ٍّخ اٌزضم١ت ثب١ٌٍضس ػٕذِب ٠ؾظً اِزظبص -4 ألشؼخ ا١ٌٍضس ِٓ لجً اٌّبدح اٌّشاد رضم١جٙب ثغجت اٌجالصِب اٌزٟ .رؾغت أشؼخ ا١ٌٍضس ػٓ اٌّؼذْ انًصـادر .6 [1] j. fieret and etal, “aerodynamic interactions during laser cutting, spie conf. vol. 668, p.53, 1986. ِظطفٝ أؽّذ سعت، ص١٘ش ع١ّٓ شىش، رؤص١ش ِزغ١شاد .د [2] اٌزشغ١ً ثؼ١ٍّخ اٌزفش٠غ اٌىٙشثبئٟ، ِٛصك ٌٍٕشش فٟ ِغٍخ اٌغبِؼخ اٌّغزٕظش٠خ، –و١ٍخ إٌٙذعخ إٌٙذعخ ٚاٌز١ّٕخ .2010-9-20فٟ (3694)اٌىزبة اٌّشلُ [3] m. v. allmen and etal, “absorption phenomena in metal drilling with nd: lasers” ieee journal quant eect. vol. qe-14, no. p.85, 1978. رؤص١ش اٌّؼبٍِخ ثب١ٌٍضس ػٍٝ رشممبد ،ِظطفٝ أؽّذ سعت. د [4] .اإلعٙبد ٌٍظٍت إٌّخفض اٌىشثْٛ ِٕشٛس فٟ ٚلبئغ ٌٍفزشح -عبِؼخ ثبثً-اٌّئرّش اٌؼٍّٟ اٌضبٌش فٟ و١ٍخ إٌٙذعخ .2011 آراس 23-24 [5] b.s.yilbas,”a study of effecting parameters in the drilling sheet metals”, journal of mechanical working technology, vol.13, p.303, 1986. [6] j.ready, “material processing”, proc. of the i‎eee, vol.70 no.6, p.556, 1982. [7] c.m. banes and etal. “macro processing”, proc. ofieee, vol.70 no.6 p.556, 1982. ِظطفٝ أؽّذ سعت، ص١٘ش ع١ّٓ شىش، رؤص١ش ِزغ١شاد .د [8] اٌزشغ١ً ثؼ١ٍّخ اٌزفش٠غ اٌىٙشثبئٟ ػٍٝ عّه اٌطجمخ اٌّؼبد و١ٍخ عجىٙب، ِٛصك ٌٍٕشش فٟ ِغٍخ د٠بٌٝ ٌٍؼٍَٛ إٌٙذع١خ َ د ع ٖ )عبِؼخ د٠بٌٝ، ؽغت اٌىزبة اٌّشلُ –إٌٙذعخ .2010-11-23فٟ (265/ [9] g. herziger,” fundamentals of laser processing of materials”, spie, vol. 668, p.2, 1989. [10] journal of soviet laser research (usa), vol.3, no.3, p.194, may, 1987. ِظطفٝ أؽّذ سعت،دلخ األثؼبد ٚطج١ؼخ األعطؼ . د [11] ِغٍخ عبِؼخ دِشك، اٌّغٍذ اٌزبعغ ػشش، اٌؼذد –اٌّشغٍخ .145-135، ص 2003االٚي، (ػ١ٍّخ اٌزشغ١ً ثبٌجشاص)ػّبد ػ١غٝ ػجذ األؽذ [12] اإلٔزبط – أطشٚؽخ ِبعغز١ش ِمذِخ اٌٝ لغُ ٕ٘ذعخ (.1998)ٚاٌّؼبدْ mustafa ahmed rijab al-khwarizmi engineering journal, vol.8, no.1, pp 86-90 (2012) 9091 effect of laser cutting methods on hole deviation and surface integrity mustafa ahmed rijab* hamid salih mahdi** *mechanical department/technical institute – baquba **department of manufacturing operations engineering / al-khwarizmi college of engineering/ university of baghdad e-mail: mostafaalnajar@yahoo.com e-mail: al_sarraf1@hotmail.com abstract in the present work usednd:yag laser systems of different output characteristic were employed to study the drilling process of material used in scientific and industrial fields. this material include manganese hard steel. our study went into the affecting parameters in drilling of manganese hard steel by laser. drilling process is achieved through material absorption of part of the incident laser beam. it is the resultant of interfering both, laser beam and material properties and the focusing conditions of the beam. the results as shown that the increase in the laser pulse energy over the used level has raised the hole diameter, depth and increased the hole taper. in addition to that a hole taper was affected by the laser energy, the focusing position and focal length of the lens used. mailto:mostafaalnajar@yahoo.com mailto:al_sarraf1@hotmail.com <4d6963726f736f667420576f7264202d20dae1ed20cce3c7e120e6c7cde3cf392d3135> al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 14, no. 4, december , (2018) p.p. 915 crack growth behavior through wall pipes under impact load and hygrothremal environment ali jamal khaled* ahmed abdul hussain** *,**department of mechanical engineering/ college of engineering/ university of baghdad *email: engalijamal93@gmail.com **email: ahmedrobot65@yahoo.com (received 12 february 2018; accepted 14 may 2018) https://doi.org/10.22153/kej.2018.05.001 abstract this research concerns study the crack growth in the wall of pipes made of low carbon steel under the impact load and using the effect of hygrothermal (rate of moisture 50% and 50℃ temperature). the environmental conditions were controlled using high accuracy digital control with sensors. the pipe have a crack already. the test was performed and on two type of specimens, one have length of 100cm and other have length 50cm. the results were, when the humidity was applied to the pipe, the crack would enhance to growth (i.e. the number of cycles needed to growth the crack will reduce). in addition, when the temperature was increase the number of cycles needed to growth the crack are reduced because the effect of heat on the mechanical properties of the material. in addition, when the test performed on the specimens of length 50cm the number of cycles needed to growth the crack is increase because the effect of bending stress on the pipes. keywords: cracks, crack initiation, crack growth, hygyothermal, pipes failure. 1. introduction cracks define as a discontinuity or break which occur in solid (rigid) body and it branded by having an initiation point and by growing from this point to finite size with time. either leading or not to the separation the original body in two or more parts. crack growth depended on the loading conditions and environmental conditions. loading conditions presents the type of load such as static load, dynamic load, load controlled, grip controlled. while environmental conditions like temperature and corrosive atmosphere influence crack growth. [1] there are three types of cracks in pipe happen due to several causes associated with their types; first the form of a crack, second its dimension and its function. [2] 1. longitudinal cracks 2. lateral cracks 3. cracks origination at a point 2. the behavior of cracks the behavior of fatigue cracks differs from that of long cracks because of larger sensitivity to the microstructure. a greater size of the plastic zone fit to the crack length, and a minimum fit to crack finish. advanced have been made in the understanding of the fatigue crack growth process of cracks, and this understanding has been employed in the advance of analytical treatments of short fatigue crack growth. the study of fatigue crack growth behavior is one of the more active areas of research in the field of fatigue. such cracks are interest not only because their growth can inhabit an important portion of the fatigue life time but also because they can grow at amount much higher or lower than might be expected on the basis on long crack behavior. there are four kinds of cracks fatigue [3] 1. mechanically cracks (the crack length is less than plastic zone size) ali jamal khaled al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 915 (2018) 10 2. micro structurally (the crack length is less than a critical microstructural) 3. physically (the crack length is less than at which crack closure if fully developed usually less than 1 mm in length) 4. chemically (the crack length may be up to 10 mm) 3. governing differential equations paris proposed the following equation for the correct crack propagation law �� �� = ∁(∆ )� … (1) where ∁ and � are constant and they depended on the material that be used. this equation seemed to have good correlation with the test data. however, if comparisons are made with the large range of data, such as a higher load ratios and crack growth rates, the correlations is not good. in fact, equation (1) does not seem to be complete. two effect occur which are not taken into account. one of this variation in the crack growth rate owing to the load ratio, r. the other is the instability of the crack growth when the value of the maximum stress intensity factor approaches to the fracture toughness of the material, kc, [4] 4. criteria of crack growth theoretical and experimental work contains different criteria like crack position, shape of crack, length of crack and crack angle. moreover, approximation for the study of the crack growing path. several of this study are created on the stress analysis of the crack tip region. erdogan and sih first examined the angled crack. they suggested the mts criteria basing the stress domain present just before the start of break for guess of the orientation of the initial crack growth. conferring to the mts criteria the crack extend in the radial way agreeing to the tangential stress and the crack growth occur then this maximum arrive a ticklish value. erdogan and sih’s study was created on the presentation of the crack tip stress region in expressions of stress function resulting by williams [5]. ∅=��/��� (θ)+�� �� (�)+��/� �� (�) ... (2) for the first term the stress are representation by: )* = � √�,-. cos � � � 0 � 123� * � − � 356�7 … (3) 8-* = � �√�, 123 � � � [ � 356� + �(3123� − 1) … (4) erdogan and sih suggested that the direction of crack growth is given by the condition: �<= �* = 0 … (5) where: * = 123� * � ( �123 * � − 3 �356 * �) … (6) 123 * � [ ?356� + ??(3123� − 1)]=0 … (7) a better covenant among the theoretical and experimental has been gotten by a personification of the stress region using the first two relations of the eigen function, equation (2). in addition, by using a lesser but finite radius to detect the maximum assessment of )* and this was exposed by williams and ewing. the elastic strain energy ab kept in parallel pipe of volume ac in the dominate sih expresses region of the strained plate: �d �e = �fg hi [ �,�k)l + )mn� + k)l − )mn� + 4(8lm)�] … (8) � = �pg �fg for plane stress … (9) � = 1 − 2q for plane strain … (10) papadopoulos used the elastic strain energy approached to suggest a standard of break, which takings into account the third stress constant det. (σij) det.k)rsn = t )l )lm)ml )m t … (11) where: )ml = )lm conferring to the det. – criteria the position of crack growth for the mixed mode loading is specified from the state that the determinate of the stress tensor necessity take a maximum rate. in a polar coordinate system, the relations express these conditions mathematically: u vwx.(z[\) u* t*]*∗= 0, u. vwx.(z[\) u*. t*]*. < 0 … (12) the ticklish stress for crack initiation is estimated by: det.()rs) = det.()rs)` … (13) 5. cyclic load equations the equations below are available for transverse crack (α = 90°) with and without internal pulse pressure [6] c = d[1 + e�f�fig hi ] … (14) j = , kh (lmh − jmh) … (15) n = iop hqi? (for simply supported) … (16) σ = st u (bending stress) … (17) σvwx = −σvyz … (18) ali jamal khaled al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 915 (2018) 11 { = �\ … (19) |} = �\ √-x … (20) ~�(|}) = 1 + 0.19|} + 0.01|}� … (21) �� = 1 + }.�}��(�p�`�x(�)) 0���(���) √. f√� ���(�)7∗� … (22) �� = 1 + }.�����k�f�`�x.(�)p`�x(�)n 0���(���) √. f���(�)7 … (23) ���? = (~�(|}) ∗ �56({) ∗ ��)/({ ∗ ��) …(24) �? = )�pp.���s���? = �?��l … (25) 6. material used and specimens the material used in this research is low carbon steel (en 10219 s235jrh). it is a pipe with a circular section thickness about 1.4 mm and a diameter about 75 mm. this research was done on several samples of this article. some of these samples have a length of 100 cm [7], see fig. 1 and other have length of 50cm see fig. 2. the reason for this difference to test the effect of bending on the growth and behavior of the crack. this test was conducted under different environmental conditions to determine the effect of the moisture and heat factors on the growth of the crack. fig.1. two sample of length 100cm. fig. 2. two sample of length 50cm. 7. manufacturing of the rig this device was made of several parts of iron material with different sections according to the required part. also used the technique of electric arc welding to connect these parts. the parts are cut using the cutting machine. after the cutting, the welding process is carried out to connect them together. however, most parts of this machine have the ability to switch when failure or damage occurs in one of these parts. the rig has the facility of making test for different length of pipes and different fixing conditions to match the requirement for the end fixing. a wooden plate was used to fix the parts of the machine. the dimensions of this plate are (122 cm x 244 cm) and thickness 1.5 cm. this plate has a hole in the middle to facilitate the passage of the hammer lever and to facilitate the examination of the pipe using the camera or naked eye. the dimensions of the parts of each other were developed using a laser device called (level) (see fig.3) that allows the device to see the extent of the separation of these parts or deviation from each other, which adds the possibility of placing the parts with high accuracy. this device enables the possibility of conducting tests on pipes made of iron, carbon steel, aluminum, copper and plastic. the design of this device includes the possibility of changing the height of the hammer to suit the amount of energy necessary and strong with the ability of the metal to withstand the shocks, also can work on the pipes of different length ranging from 50 cm to 150 cm and different diameters ranging from 2 to 4 inch. in addition, the researcher or worker on this device can control the environmental conditions to be operated from heat, humidity, and control where it can work in the areas of temperature ranging from 0 °c to 100 °c. also, control the humidity, where it can work in the humidity ratio ranging from 0% to 100%. fig. 3. level device. ali jamal khaled al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 915 (2018) 12 8. material properties these properties from din en 10219 1. chemical composition chemical composition is in percentage by mass. see table 1. 2. mechanical properties these mechanical properties measured at room temperature, see table 2 3. physical properties. physical properties for this material shown in the table 3. table 1, chemical properties of material carbon c silicon si manganese mg phosphorus p sulfur ag nitrogen n 0.17 1.4 0.04 0.04 0.009 table 2, mechanical properties of material yield strength in n/mm2 min for nominal wall thickness 235 tensile strength in n/mm2 for nominal wall thickness 360-510 elongation % for nominal wall thickness 24 impact energy in j at temperature 20°c 27 table 3, physical properties of material density at 20°c in kg/dm3 7.85 modulus of elasticity kn/mm2 at 20°c 210 thermal conductivity at 20°c in w/ m k 54 spec. thermal capacity at 20°c j/kg k 461 spec. electrical resistivity at 20°c ω mm²/m 0.15 9. crack initiation the crack was created manually by handsaw. because that the crack is difficult to accomplish using other machines. where the length of the cut about 24% [8] of the perimeter of the pipe. this percentage was based on previous research, where the length was 56 mm and width of the crack is about 0.7 mm to 0.9 mm. this difference is due to the difference in the thickness of the cutting edge in the saw as well as the hand movement. other percentages were chosen to indicate the possibility of conducting the search on different lengths of the crack. however, these lengths of (18mm, 25mm, 30mm, and 40mm) took a long time without any continuity in the growth of the crack. 10. results and calculations table 4. and table 5. show the calculations that must be used in this search, then use it in the governing equations, table 6 and table 7. to ensure the regular work convicted by equations in point 5. results were obtained by using rig made for testing these specimens. see fig. 4, the tests were repeated again to ensure a close test result as well as to ensure the correct functioning of the rig. the results are shown in the fig. 8, fig. 9, fig. 10, and fig. 11. outer diameter (od) =0.075m, inner diameter (id) =0.0722m, thickness (t) = 0.0014m yield point= 235 mpa, modules of elasticity (e) = 210gpa, high (h) =0.57m, weight of hammer (w) = 6.7kg table 4, calculation for 100cm specimens. effective length is 1 m load applied n moment of inertia �� deflection � bending stress mpa 2279.3 0.22 ∗ 10pk 0.0103 1949.1 table 5, calculations for 50cm specimens effective length is 0.5 m load applied n moment of inertia �� deflection � bending stress mpa 2223.2 0.22 ∗ 10pk 0.0018 1378.1 ali jamal khaled al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 915 (2018) 13 table 6, calculation using cyclic load equations for 100cm specimens type of test k1 k2 slop (�) without lhs rhs lhs rhs lhs rhs 1.8*10q 1.8*10q 1.87*10q 1.87*10q 6.91 8.4 hygrothermal 1.3*10� 1.3*10� 1.34*10� 1.38*10� 6.02 2.4 table 7, calculation using cyclic load equations for 50cm specimens type of test k1 k2 slop (�) without lhs rhs lhs rhs lhs rhs 1.33*10q 1.33*10q 1.35*10q 1.35*10q 2 7.6 hygrothermal 9.22*10q 9.5*10q 9.28*10q 9.7*10q 3.9 7 fig. 4. the rig used in this research. fig. 5. humidifier device. fig. 6. support. fig.7. close up photo show the crack and crack growth. fig. 8. show number of cycle of 100cm specimens. fig. 9. show number of cycle of 50cm specimen. hamme chamber support ali jamal khaled al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 915 (2018) 14 fig. 10. effect of hygrothermal on crack growth for 100cm specimens. fig.11. effect of hygrothermal on crack growth for 50cm specimens. 11. conclusion the purpose of this study is to determine the extent to which the crack is able to grow when shedding and how long it takes to grow these cracks. some things need to be discussed to know what changes are made to these cracks and to make things better. 1the number of cycle needed to growth the crack are reduced due to the effect of humidity because the formation of oxides on the fracture surface. 2the number of cycle needed to growth the crack in the specimens of length 50cm are increase because the effect of bending stress in the pipes. 3the number of cycles needed to growth the crack are reduced because the effect of heat on the mechanical properties of the material that helps to increase the ductility. notations lefm linear elastic fracture mechanics mts multi-tasking staff da/dn crack growth per cycle, m/cycle r,θ polar coordinate, dimensionless k1 , k2 stress intensity factor, mpa√� � young modulus, gpa greek letters π mathematical constant, dimensionless q poison ratio, dimensionless n deflection, m � angle of crack propagation, degree 8-* shear stress in cylindrical coordinate, mpa )l , )m , 8lm component of stress tensor, mpa )* circumferential stress near crack tip, mpa { non dimensional factor, unit less 12. references [1] bertram broberg, k., 1999, cracks and fracture academic press, pages 1-4, isbn: 978-0-12-134130-5 [2] stein, d., 2004, rehabilitation and maintenance of drains and sewers, technique technology center [3] mcevily, a. j, 1996, the growth of short fatigue crack, transaction of material science, vol. 13, pages 1-5 [4] forman, r. g., kearney, v. e., engle, r. m., 1967, numerical analysis of crack propagation in cyclic loaded structures, pages 459-463 [5] wasiluk, b., golos, k., 2000, prediction of crack growth direction under plane stress for mixed mode i and ii loading, pages 6 [6] al laham s., ainsworth r. a.,1999, stress intensity factor and limit load handbook, british energy generation ltd., uk [7] anil, o., erdem, r. t., kantar, e., 2015, improving the impact behavior of pipes using geofoam layer for protection, international journal of pressure vessel and piping, pages 52-64 [8] g. m. wilkowski, gadiali, n., rudland, d., krishanswamy, p., rahman, s., scott, p., 1994, short cracks in piping and pipe welds, vol 4, no 1, pages 78 )2018( 915، صفحة 4د، العد14دجلة الخوارزمي الهندسية المجلم علي جمال خالد 15 نمو الصدوع وتصرفها خالل جدران االنابيب المعرضة ألحمال صدمية ومحيط حار ورطب **ناحمد عبد الحسي * علي جمال خالد كلية الهندسة / جامعة بغداد قسم الهندسة الميكانيكية/*،** gmail.com93alengalijam@: يالبريد اإللكترون* yahoo.com65ahmedrobot@البريد االلكتروني: ** الخالصة ٥٠الحرارة (يتناول هذا البحث دراسة نمو الصدع في جدار االنابيب المصنوعة من الفوالذ منخفض الكربون تحت تأثير حمل الصدمة واستخدام تأثير وي على صدع . تم التحكم في الظروف البيئية باستخدام جهاز تحكم عالي الدقة مع أجهزة االستشعار. االنابيب تحت)%٥٠( بنسبة الرطوبةمئوية) ودرجة ق الرطوبة سم. عند اجراء االختبار فأن النتائج كانت، عند تطبي٥٠سم واألخر ذو طول ١٠٠ذو طول على نوعين من النماذج أحدهااالختبار اجري و مسبق، الشق سوف يقل بسبب تأثير درجة الحرارة على نموكذلك عند تطبيق الحرارة فأن عدد الدورات الالزم ل فأن عدد الدورات الالزمة لنمو الصدع سوف تقل. سم فأن عدد الدورات الالزم لنمو الشق سوف يزداد نتيجة لتأثير ٥٠اجراء االختبار على النماذج ذات الطول فعندذلك فضال عن الخواص الميكانيكية للمعدن . اجهاد االنحناء على االنابيب جاسم محمد al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 8, no. 3, pp 81 94 (2012) natural convection heat transfer in an inclined open-ended square cavity with partially active side wall jasim m. mahdi department of energy engineering/ college of engineering/ university of baghdad e-mail: jasim_ned@yahoo.com (received 10 november 2011; accepted 7 august 2012) abstract this paper reports a numerical study of flow behaviors and natural convection heat transfer characteristics in an inclined open-ended square cavity filled with air. the cavity is formed by adiabatic top and bottom walls and partially heated vertical wall facing the opening. governing equations in vorticity-stream function form are discretized via finitedifference method and are solved numerically by iterative successive under relaxation (sur) technique. a computer program to solve mathematical model has been developed and written as a code for matlab software. results in the form of streamlines, isotherms, and average nusselt number, are obtained for a wide range of rayleigh numbers 103-106 with prandtl number 0.71 (air) , inclination angles measured from the horizontal direction 0º-60º , dimensionless lengths of the active part 0.4-1 ,and different locations of the thermally active part at the vertical wall. the results show that heat transfer rate is high when the length of the active part is increased or the active part is located at middle of vertical wall. further, the heat transfer rate is poor as inclination angle is increased. keywords: natural convection, square cavity, partially active side wall. 1. introduction natural convection in a cavity with one vertical side open has received increasing attention in recent years due to its importance in a number of practical applications such as heat transfer and fluid flow in solar thermal receiver systems [1], fire spread from room [2], and cooling of electronic equipment [3]. many theoretical and experimental studies on natural convection in the 2-d open square cavity have been carried out [4]–[10]. for the sake of brevity literature review will be only restricted to studies of natural convection in open square cavities with adiabatic walls and isothermal at the wall facing the aperture. chan and tien [4] performed a numerical study of laminar natural convection in a two-dimensional square open cavity with a heated vertical wall and two insulated horizontal walls. to overcome the difficulties of unknown conditions at the opening, they made their calculations in an extended computational domain beyond the opening. results obtained for rayleigh numbers ranging 103 106 were found to approach those of natural convection over a vertical isothermal flat plate. later on, the same authors [5] investigated open shallow cavity for rayleigh numbers up to 106 to test the validity of approximate boundary conditions at the opening for a computational domain restricted to the cavity instead of using an extended domain. they concluded that for a square open cavity having an isothermal vertical side facing the opening and two adiabatic horizontal sides, satisfactory heat transfer results could be obtained by the restricted domain. polat and bilgen [6] numerically studied inclined fully open shallow cavities in which the side facing the opening was heated by constant heat flux, and two adjoining walls being adiabatic over rayleigh number values ranging 103 1010. the opening was in contact with a reservoir at constant temperature and pressure; the computational domain was restricted to the cavity. they observed that heat transfer approaches asymptotic values at rayleigh numbers independent of the aspect ratio and asymptotic mailto:jasim_ned@yahoo.com jasim m. mahdi al-khwarizmi engineering journal, vol. 8, no. 3, pp 8194 (2012) 82 values are close to that for a flat plate with constant heat flux. chakroun [7] performed an experimental investigation to study the effect of wall conditions as well as its tilt angle on heat transfer for a fully open tilted cavity. his study contains seven different wall configurations over an inclination angle measured from the vertical direction range −90º to +90º. it was concluded that thetilt angle, wall configuration, and number of hot walls are all factors that strongly affect the natural convection inside the fully open cavity. nateghi and armfield [8] numerically studied natural convection flow in a two dimensional inclined open cavity for both transient and steady-state flow over rayleigh numbers ranging 105 1010 with prandtl number 0.71 and inclination angles 10º 90º. their results showed that the flow is steady at the low rayleigh number for all angles and becomes unsteady at the high rayleigh number for all angles and the critical rayleigh number decreases as the inclination angle increases. hinojosa et al. [9] presented results for natural convection and surface thermal radiation in a square tilted open cavity. effects of rayleigh number 103 107 and inclination angles 0º 180º are investigated for a fixed prandtl number (0.7). the results show that the convective nusselt number changes substantially with the inclination angle of the cavity, while the radiative nusselt number is insensitive to the orientation change of the cavity. mohamad et al. [10] simulated the natural convection in an open cavity using lattice boltzmann method. the paper demonstrated that open boundary conditions used at the opening of the cavity are reliable, where the predicted results are similar to that of conventional cfd method. prandtl number is fixed to 0.71 while rayleigh number and aspect ratio of the cavity are changed in the range of 104 to 106 and of 0.5 to 10, respectively. the results show that the rate of heat transfer deceases asymptotically as the aspect ratio increases and may reach conduction limit for large aspect ratio. most of the above-cited works deal with the active vertical wall of the cavity at isothermal or isoflux condition. in real life such as in fields like solar energy collection and cooling of electronic components, the active wall may be subject to abrupt temperature nonuniformities due to shading or other natural effects[11], therefore only a part of the wall is either in isothermal or isoflux condition. the present study deals with the natural convection in an open square cavity filled with air as working fluid with partially thermally active vertical wall, for different lengths of thermally active part. the active part is located at the top, middle and bottom to locate the position where the heat transfer rate is maximum and minimum. 2. mathematical formulation the geometry, the coordinate system, and the boundary conditions for the problem under consideration are shown in fig. (1). a portion of the right side wall of the cavity is kept at a temperature th and the remaining parts are insulated. under the assumptions of a twodimensional viscous incompressible fluid with steady-state conditions, the equations governing the motion and the temperature distribution inside the cavity may be written as: [12] continuity equation ∂u∂χ + ∂v∂y = 0 …(1) conservation of momentum in x-direction ρ u ∂u∂χ + v ∂u∂y = −∂p∂x +μ ∂ u∂x + ∂ u∂y + ρgsinφ …(2) conservation of momentum in y-direction ρ u ∂v∂χ + v ∂v∂y = −∂p∂y +μ ∂ v∂x + ∂ v∂y − ρgcosφ …(3) energy equation u ∂t∂χ + v∂t∂y = α ∂ t∂x + ∂ t∂y …(4) as in many investigations of natural convection, all fluid properties, except density in buoyancy term(ρg), are assumed constants and the boussinesq approximation is used to incorporate the temperature dependence of density in the momentum equation. in this approximation the density in buoyancy term is assumed to be a linear function of temperature, ρ = ρ∞ 1 − β(t − t∞) [12]. the use of vorticity–stream function formulation can eliminate pressure gradient terms from momentum equations and simplify the solution procedure. with the stream function, the velocity components u and v and vorticity can be expressed as: jasim m. mahdi al-khwarizmi engineering journal, vol. 8, no. 3, pp 8194 (2012) 83 u = −∂ψ∂y , v = ∂ψ∂x and ω = ∂u∂y − ∂v∂x furthermore by introducing the following no dimensional variables: (x, y) = (x, y) l ,⁄ (u, v) = (u, v) (α l⁄ )⁄ ψ = ψ α⁄ , ω = ω (α l ⁄ ),⁄ θ = (t − t∞) (t − t∞)⁄ with t > t∞ , the governing equations in terms of vorticitystream function form become: stream function ∇ ψ = −ω …(5) vorticity ∇ ω = 1pr u ∂ω∂χ + v ∂ω∂y −ra ∂θ∂χ cosφ − ∂θ∂y sinφ …(6) energy ∇ θ = u ∂θ∂χ + v ∂θ∂y …(7) where u = −∂ψ∂y v = ∂ψ∂x …(8) the dimensionless parameters appearing in equations (5) through (8) are the prandtl number pr = ν α⁄ and the rayleigh number ra =gβ(t − t∞)l αν⁄ . other parameters which enter into this study are the dimensionless length of the active part h = (0.4 ≤ h ≤ 1) and the dimensionless position of the active part center s = (h 2⁄ ≤ s ≤ 1 − h 2⁄ ). the appropriate boundary conditions in dimensionless form can be formulated as: at x = 0 , s ≤ y ≤ s + , ψ = 0 ω = −∂ ψ∂x θ = 1 at x = 0, 0 ≤ y < − , s + < ≤ 1, ψ = 0 ω = −∂ ψ∂x ∂θ∂x = 0 at 0 < x < 1 , y = 0,1 , and ψ = 0 ω = −∂ ψ∂y ∂θ∂y = 0 at x = 1 , 0 < y < 1. ψ = ω = 0, θ = 0 if u ≤ 0 (in low ) θ = 0 if u > 0(out low) local nusselt number on thermally active part is defined by: nu = − h lk = lt − t∞ ∂t∂x where the local heat transfer coefficient hy is defined by equating heat transfer by convection to that by conduction at the active part: h(t − t∞) = −k ∂t∂x by introducing the dimensionless variables defined above, local nusselt number will be: nu = θ the average nusselt number is obtained by integrating local nusselt number over the active part: nu = nu. dy ( ⁄ ) ( ⁄ ) fig. 1. schematic of the square cavity, the coordinate system and boundary conditions. 3. numerical technique a finite difference method (fdm) with central difference scheme is used to discretize the system of the partial differential equations (5 8). the new algebraic equations system will be solved using iterative under relaxation method (urm), to give approximate values of the dependent variables at a number of discrete points called (grid points or nodes) in the computational domain. these nodes are formed by subdividing the computational domain in the x and y directions with vertical and horizontal uniformly s h th l x y l g φ jasim m. mahdi al-khwarizmi engineering journal, vol. 8, no. 3, pp 8194 (2012) 84 spaced grid lines. based on a grid independence study a grid of 61 × 61 nodes is adopted typically in this study. however, a careful check for the grid independence of the numerical solution has been made to ensure the accuracy and validity of the numerical schemes. for this purpose, four grid systems, 45×45, 61×61, 81×81, and 101×101 are tested. results show the average nusselt number prediction for 61×61 grid points nearly correspond to that obtained from other grid points, the maximum relative error (% є) obtained through the five grid systems is no more than 1% as shown in table (1). the accuracy of the numerical code was assessed by applying it to a case studied by mohamad et al. [10], who considered a cavity configuration similar to that being considered in this paper with a fully active hot vertical wall, and good agreement was observed, as shown in table (2). the maximum difference obtained for the average nusselt number at the hot vertical wall was 1.7 %. furthermore, in order to lend more confidence in the present numerical results, the results in form of isothermals contours were compared with those of nateghi and armfield [8] and mohamad et al. [10]; and an excellent agreement was achieved, fig.(2).the convergence criteria employed to terminate the computations and reach the solution were preassigned as (ψζ ψζ-1)/ψζ ≤ 10-6, (θζ θζ-1)/θζ ≤ 10-6, and (ωζ ωζ-1)/ ωζ ≤ 10-6, the indices ζ and ζ −1 represent the current and previous iteration, respectively. table 1, grid independence study results for average nusselt number. % є 101×101 81×81 61×61 45×45 size 1.0 1.189 1.188 1.180 1.173 ra = 103 0.5 3.318 3.327 3.319 3.308 ra = 104 0.3 7.298 7.301 7.301 7.284 ra = 105 0.7 14.27 14.23 14.22 14.32 ra = 106 table 2, comparison of the obtained results for average nusselt number with literature. difference (%) nu [this study] nu [10] ra 1.7 3.319 3.377 104 0.2 7.301 7.323 105 1.1 14.22 14.38 106 4. results and discussion in this section, the numerical results in form of the streamlines, isotherms, and average nusselt numbers for various values of the parameters governing the heat transfer and fluid flow will be presented and discussed. the parameters are location of thermally active part, the dimensionless length of thermally active part, h = 0.4 1.0, rayleigh number, ra = 103 106, and inclination angle, φ =0º 60º. prandtl number, pr = 0.71 for air was kept constant. in figures (3-6), the darkened area of side wall indicates the position of thermally active part while the symbol ( ) represents the center of the circulation which defined as the point of the extremum of the stream function ψmax. the scenario of development natural convective currents inside open cavity begins when the air in contact with the active part of side wall heated by conduction, becomes lighter, and ascends in adjoin to the side wall to face the adiabatic upper wall and then through which it moves horizontally to leave the cavity from the upper part of the aperture. in order to retrieve fluid left outside the cavity, fresh air entrained from the lower part of the aperture toward heated portion of side wall to be heated and resulting in clockwise recirculation inside cavity, as shown in left sides of figs. (3-6). 4.1. effect of active part length the effects of active part length h on flow and temperature fields are shown in figure (3) for rayleigh number, ra = 105, inclination angle, φ =0° and position of active part is at middle. the values of maximum stream functions ψmax show that higher values are obtained with increasing the active part length from h=0.4 to h=1. in fact, when the active part is wider major portion of the cavity is occupied by circulating cells (see streamlines in fig. (3)) and flow strength increases making the cavity more significantly affected by the buoyancy-driven flow. the corresponding isotherms indicate that as h increases the isotherms are denser near the active part that means thermal boundary layer becomes thinner and temperature gradients becomes steeper due to strong convection. the amount of heat transferred from the active part across the cavity obviously increases as the length h of the thermally active part increases due to higher heat transfer surface. correspondingly, average nusselt number which would describe the thermal jasim m. mahdi al-khwarizmi engineering journal, vol. 8, no. 3, pp 8194 (2012) 85 behavior of the cavity should increase with increasing h as shown in fig. (7). 4.2. effect of active part location figure (4) shows the effect of active part position on the streamlines and isotherms patterns at ra = 105, φ =0°, and dimensionless length of active part, h=0.4. in fact, due to impingement of circulated fluid to the middle of the vertical wall and impingement of hot fluid to the top adiabatic wall, fluid at right top and bottom corner becomes motionless and also, the half bottom of the cavity becomes cooler than the upper one. thus strength of circulation becomes larger, as clearly denoted by the higher value of ψmax, and major portion of the cavity is occupied by circulating cells as the active part occupies a position lower in the cavity (see streamlines in fig. (4)). in contrast, when the active part is located at the bottom or the top of vertical wall the rising fluid by buoyancy force cannot wash the entire surface of the active part and thermal boundary layer around the active part gets thicker (see isotherms in fig. (4)), thus the amount of heat exchanged is smaller than that exchanged when the active part is located at middle of vertical wall. subsequently, the average nusselt number which describes the overall heat transfer process through the cavity is higher when the active part located at middle as shown in fig. (8). 4.3. effect of inclination the effect of inclination angle φ in the range of 0 to 60◦ which covering practical cases in solar collectors [6] is examined for ra=105 and h=0.6. fig. (5) shows the effect of inclination angle on streamlines and isotherms patterns. streamlines show that as the inclination is increased flow of the hot fluid from the aperture is choked and a smaller part of the upper region of the cavity is occupied by discharged fluid. as a result, the center of the circulation is impelled upward indicating significant increase in fluid velocities. the isotherms show a thicker thermal boundary layer is formed on the active part of side wall, and also a thinner hot intrusion on the upper insulated wall formed as inclination angle increases. increasing the inclination angle in the range 0º ≤ φ ≤ 60º leads to a decrease in the average nusselt number for the same dimensionless length of active part as shown in fig. (9). this because as φ increases, the thermal boundary layer on active part get thicker and fluid thermal stratification in the upper region of the cavity get poorer (see isotherms in fig. (5)), since flow of the hot fluid from the aperture is choked as the inclination is increased and that leads to slower replacement of the hot air by fresh air and that makes convection less rigorous. 4.4. effect of rayleigh number figure (6) shows the effect of increasing rayleigh number in the range (103-106) on streamlines and isotherms patterns at h=0.8 and φ =0°. usually, the rayleigh number, is defined by (ra = gβl3δt/να), and in case of using boussinesq approximation with air as a working fluid, the ν, α and g will be constants. thus, only β and δt will be the factors that govern the change in value of rayleigh number. in case of ra =103 , the circulation inside the cavity is so weak that the viscous forces are dominant over the buoyancy force and that leads to rather weak convection, also the effect of the open side does not seem deep in this case. consequently, the corresponding isotherms exhibit rather slight difference as compared to those of pure heat conduction which are parallel to the surface of the thermally active part. on the other hand, when rayleigh number increases, the buoyancy force accelerates the circulation of fluid flow and the effect of the open side penetrates further into the flow. as a result, the corresponding isotherms are greatly deformed and crowded near the active part leaving the cavity core empty. therefore, as rayleigh number increases, the flow becomes fully convective dominated, the fresh fluid is entrained right to the left vertical wall where high temperature gradients are created, and the discharging fluid from the upper part of the cavity occupies smaller section of the opening. it is interesting to note in case of ra = 106, the formation of vortex in the upper portion of the cavity due to the high heat transfer rate, also the effect of the open side is quite significant in this case. jasim m. mahdi al-khwarizmi engineering journal, vol. 8, no. 3, pp 8194 (2012) 86 (a) pr = 0.71 ra = 105 φ = 0º h=1 (b) pr = 0.71 ra = 105 φ = 10º h=1 fig. 2. comparison of isotherms with those of (a) mohamad et al.[10] and (b) nateghi and armfield [8]. jasim m. mahdi al-khwarizmi engineering journal, vol. 8, no. 3, pp 8194 (2012) 87 streamlines isotherms a) h = 0.4 b) h = 0.6 c) h = 0.8 d) h = 1 fig. 3. streamlines and isothermal contours for φ=0º, location of active part at middle and ra =105, with different lengths of thermally active part. 1.6 1.6 1.6 1.6 3.2 3.2 3.2 3.2 4.8 4.8 4.8 4.8 6.4 6.4 6.4 6.4 8 8 8 9.6 9.6 9.6 11.2 11.2 11.2 12.8 12.8 14.4 0. 1 0.1 0.1 0. 2 0.2 0.2 0. 3 0.3 0.3 0. 4 0.4 0.4 0. 5 0.5 0. 6 0.6 0. 7 0. 8 0. 91 1.7 1.7 1.7 1.7 3.4 3.4 3.4 3.4 5.1 5.1 5.1 5.1 6.8 6.8 6.8 6.8 8.5 8.5 8.5 10.2 10.2 10.2 11.9 11.9 11.9 13.6 13.6 15.3 0. 1 0.1 0.1 0. 2 0.2 0.2 0. 3 0.3 0.3 0. 4 0.4 0.4 0. 5 0.5 0.5 0. 6 0.6 0. 7 0 .7 0. 8 0. 91 1.8 1.8 1.8 1.8 3.6 3.6 3.6 3.6 5.4 5.4 5.4 5.4 7.2 7.2 7.2 7.2 9 9 9 9 10.8 10.8 10.8 12.6 12.6 12.6 14.4 14.4 16.2 0.10.1 0. 1 0.2 0.2 0. 2 0. 3 0.3 0.3 0. 4 0.4 0.4 0. 5 0.5 0.5 0. 6 0.6 0.6 0. 7 0.7 0. 8 0. 8 0. 9 0.9 1 1 1.8 1.8 1.8 1.8 3.6 3.6 3.6 3.6 5.4 5.4 5.4 5.4 7.2 7.2 7.2 7.2 9 9 9 9 10.8 10.8 10.8 12.6 12.6 12.6 14.4 14 .4 14.4 16.2 0.10.1 0.1 0.2 0.2 0. 2 0.3 0.3 0. 3 0.40. 4 0. 4 0.50.5 0. 5 0.5 0. 6 0.6 0.6 0. 7 0.7 0. 8 0.8 0. 9 0. 9 1 1 ψmax = 15.4 ψmax = 16.5 ψmax = 17.5 ψmax = 18.0 jasim m. mahdi al-khwarizmi engineering journal, vol. 8, no. 3, pp 8194 (2012) 88 streamlines isotherms a) bottom location b) middle location c) top location fig. 4. streamlines and isothermal contours for φ=0º, h=0.4 and ra =105 with different locations of thermally active part. 1.1 1.1 1.1 1.1 2.2 2.2 2 .2 2.2 3.3 3.3 3.3 3.3 4.4 4.4 4.4 5.5 5.5 5.5 6.6 6.6 7.7 7.7 8.8 9.9 0.1 0.1 0.2 0.2 0.3 0.3 0.3 0. 4 0.4 0.4 0.5 0.5 0. 6 0.6 0.70.8 0. 91 1. 6 1.6 1.6 1.6 3.2 3.2 3 .2 3.2 4.8 4.8 4.8 4.8 6.4 6.4 6.4 6.4 8 8 8 9.6 9.6 9.6 11.2 11.2 11.2 12.8 12.8 14.4 0. 1 0 .1 0.1 0. 2 0.2 0.2 0. 3 0.3 0.3 0. 4 0.4 0.4 0. 5 0.5 0. 6 0.6 0. 7 0. 8 0. 91 1 .8 1.8 1.8 1.8 3.6 3.6 3.6 3.6 5.4 5.4 5.4 5.4 7.2 7.2 7.2 7.2 9 9 9 9 10.8 10.8 10.8 12.6 12.6 12.6 14.4 14.4 14.4 16.2 16.2 0.1 0.1 0.1 0.2 0.2 0. 2 0. 3 0.3 0.3 0.4 0.4 0 . 5 0 . 6 0. 7 0. 8 0. 91 ψmax = 17.8 ψmax = 15.4 ψmax = 10.5 jasim m. mahdi al-khwarizmi engineering journal, vol. 8, no. 3, pp 8194 (2012) 89 fig. 5. streamlines and isotherms for h=0.6, location of active part at middle and ra=105 with different values of inclination angles. streamlines isotherms a) φ=0º b) φ=30º c) φ=60º 1.7 1.7 1.7 1.7 3.4 3.4 3.4 3.4 5.1 5.1 5.1 5.1 6.8 6.8 6.8 6.8 8.5 8.5 8.5 10.2 10.2 10.2 11.9 11.9 11.9 13.6 13.6 15.3 0. 1 0.1 0.1 0. 2 0.2 0.2 0. 3 0.3 0.3 0. 4 0.4 0.4 0. 5 0.5 0.5 0. 6 0.6 0. 7 0.7 0. 8 0. 91 2.7 2.7 2.7 2.7 5.4 5.4 5.4 5.4 8.1 8.1 8.1 8.1 10.8 10.8 10.8 13.5 13.5 13.5 16.2 16.2 16.2 18.9 18.9 21.6 21.6 24.3 0. 1 0.1 0.1 0. 2 0.2 0.2 0. 3 0.3 0.3 0. 4 0.4 0.4 0. 5 0.5 0. 6 0.6 0. 7 0.7 0. 8 0. 91 2.7 2.7 2.7 2.7 5.4 5.4 5.4 5.4 8.1 8.1 8.1 10.8 10.8 10.8 13.5 13 .5 13.5 16.2 16.2 18.9 18.9 21.6 21.6 24.3 0. 1 0.1 0.1 0. 2 0.2 0.2 0. 3 0.3 0.3 0. 4 0.4 0.4 0. 5 0.5 0. 6 0.6 0. 7 0.7 0. 8 0. 91 ψmax = 16.5 ψmax = 26.0 ψmax = 27.1 jasim m. mahdi al-khwarizmi engineering journal, vol. 8, no. 3, pp 8194 (2012) 90 0.16 0.16 0.16 0.16 0.32 0.32 0.32 0.32 0.48 0. 48 0.48 0.64 0. 64 0.64 0.8 0. 8 0.8 0.96 0. 96 0.96 1.12 1. 12 1.12 1.28 1.28 1.44 1.44 1.6 0. 1 0.2 0.2 0.3 0. 3 0.4 0. 4 0.5 0.5 0. 6 0. 6 0. 7 0. 7 0. 8 0. 8 0. 9 0.9 1 1 streamlines isotherms a) ra = 103 b) ra = 104 c) ra = 105 d) ra = 106 fig. 6. streamlines and isotherms for φ=0º, location of active part at middle and h =0.8, with different values of rayleigh number. 0.7 0.7 0.7 0.7 1.4 1.4 1.4 1.4 2.1 2.1 2.1 2.1 2.8 2.8 2.8 3.5 3.5 3.5 4.2 4.2 4.2 4.9 4. 9 4.9 5.6 5. 6 5.6 6.3 6.3 0.1 0.1 0.2 0.2 0.2 0.3 0.3 0.3 0.4 0.4 0. 4 0.5 0.5 0. 5 0. 6 0.6 0. 6 0. 7 0.7 0. 8 0.8 0. 9 0.9 1 1 1.8 1.8 1.8 1.8 3.6 3.6 3.6 3.6 5.4 5.4 5.4 5.4 7.2 7.2 7.2 7.2 9 9 9 9 10.8 10.8 10.8 12.6 12.6 12.6 14.4 14.4 16.2 0.10.1 0. 1 0.2 0.2 0. 2 0. 3 0.3 0.3 0. 4 0.4 0.4 0. 5 0.5 0.5 0. 6 0.6 0.6 0. 7 0.7 0. 8 0. 8 0. 9 0.9 1 1 3.6 3.6 3.6 3.6 7.2 7.2 7.2 7.2 10.8 10.8 10.8 10.8 14.4 14.4 14.4 14.4 18 18 18 18 21.6 21.6 21.6 21.6 25.2 25.2 25.2 28.8 28.8 32.4 0. 1 0.1 0.1 0. 2 0.2 0.2 0. 3 0. 3 0.3 0.3 0. 4 0. 4 0.4 0.4 0. 5 0 . 5 0.5 0.5 0. 6 0. 6 0.6 0. 7 0.7 0. 8 0. 8 0. 9 0. 9 1 1 ψmax = 35.2 ψmax = 17.5 ψmax = 6.9 ψmax = 1.7 jasim m. mahdi al-khwarizmi engineering journal, vol. 8, no. 3, pp 8194 (2012) 91 fig. 7. average nusselt number as a function of rayleigh number for different dimensionless lengths of active part at φ=0º and location of active part at middle. fig. 8. average nusselt number as a function of rayleigh number for different locations of thermally active part at φ=0º and h=0.4. fig. 9. average nusselt number as a function of rayleigh number for different inclination angles at h=0.4 and location of active part at middle. 10 3 10 4 10 5 10 6 0 2 4 6 8 10 12 14 16 18 20 ra n u h = 0.4 h = 0.6 h = 0.8 h = 1.0 103 104 105 106 0 1 2 3 4 5 6 7 8 9 10 ra n u bottom position middle position top position 103 104 105 106 0 2 4 6 8 10 12 ra n u φ = 0° φ = 30° φ = 45° φ = 60° jasim m. mahdi al-khwarizmi engineering journal, vol. 8, no. 3, pp 8194 (2012) 92 5. conclusions a steady, two-dimensional natural convection heat transfer in a square open cavity with partially active side wall has been studied numerically for different angles of inclination, different rayleigh numbers and different lengths and locations of thermally active part. the finite-difference method was employed for the solution of the present problem. graphical results in form of streamlines and isotherms for various parameters governing heat transfer and fluid flow were presented and discussed. the results of the present study lead to the following conclusions: • location and length of the active part, rayleigh number and inclination angle are important parameters on flow and temperature fields and heat transfer in square cavity. • heat transfer increases with the increasing of active part length or rayleigh number. values of stream function (flow strength) also increase with the increasing of rayleigh number or active part length. • higher heat transfer rate was obtained when the active part is at middle location in vertical wall compared to top and bottom locations. • increase of inclination angle increases flow strength and decreases average nusselt number. nomenclature l length of the square cavity g gravitational acceleration h h length of the active part dimensionless length of the active part s s position of the active part center dimensionless position of the active part hy local heat transfer coefficient nu local nusselt number nu average nusselt number p pressure t dimensional temperature pr prandtl number (ν/α) ra rayleigh number (gβl3δt/να) x,y x,y dimensional cartesian coordinates dimensionless coordinates u u v dimensional velocity in the x-direction dimensionless velocity in the x-direction dimensional velocity in the y-direction v dimensionless velocity in the y-direction greek symbols α thermal diffusivity β μ thermal expansion coefficient dynamics viscosity ν ω kinematic viscosity dimensional vorticity ω dimensionless vorticity ψ dimensional stream-function ψ dimensionless stream-function θ dimensionless temperature ρ density δ laplacian in cartesian coordinates subscripts ∞ ambient in inflow out outflow superscripts ζ current iteration number ζ-1 previous iteration number 6. references [1] a. m. clausing, convective losses from cavity solar receivers: comparisons between analytical prediction and experimental results, j. solar energy 105 (1983) 29-33. [2] abdulkarim h. abib, yogesh jaluria, penetrative convection in a partially open enclosure, htd 198 asme (1992) 74–83. [3] s. s. cha and k. j. choi. an interferometric investigation of open cavity natural convection heat transfer. exp. j. heat transfer 2 (1989) 27–40. [4] y.l. chan, c.l. tien, a numerical study of two-dimensional natural convection in square open cavities, numer. heat transfer 8 (1985) 65–80. [5] y.l. chan, c.l. tien, a numerical study of two-dimensional laminar natural convection in shallow open cavities, int. j. heat mass transfer 28 (1985) 603–612. [6] o. polat, e. bilgen, laminar natural convection in inclined open shallow cavities, int. j. thermal sciences 41 (2002) 360–368. [7] chakroun, w., effect of boundary wall conditions on heat transfer for fully opened tilted cavity, asme j. heat transfer, 126 (2004) 915–923. jasim m. mahdi al-khwarizmi engineering journal, vol. 8, no. 3, pp 8194 (2012) 93 [8] m. nateghi, s. w. armfield, natural convection flow of air in an inclined open cavity, anziam journal 45 (2004) 870–890. [9] j.f. hinojosa, r.e. cabanillas, g. alvarez, c.e. estrada, nusselt number for the natural convection and surface thermal radiation in a square tilted open cavity , int. communications in heat and mass transfer 32 (2005) 1184–1192. [10] a.a. mohamad a, m. el-ganaoui b, r. bennacer c, lattice boltzmann simulation of natural convection in an open ended cavity, int. j. thermal sciences 48 (2009) 1870–1875. [11] n. nithyadevi, p. kandaswamy, j. lee, natural convection in a rectangular cavity with partially active side walls, int. j. heat mass transfer 50 (2007) 4688–4697. [12] p.j. roach, computational fluid dynamics, hermosa, albuquerque, new mexico, 1985. )2012( 81 94 ، صفحة3، العدد8 مجلة الخوارزمي الھندسیة المجلد د مھدي جاسم محم 94 إنتقال الحرارة بالحمل الحر في تجویف مربع مائل ذو نھایة مفتوحة و بوجود جزء نشط حراریًا جاسم محمد مھدي جامعة بغداد/ كلیة الھندسة /قسم ھندسة الطاقة jasim_ned@yahoo.com : االلكتروني البرید الخالصة ُمحاط بجدارین علوي و سفلي مفتوح من الجانب مائل مربع الشكل وفي حیز الحمل الطبیعي نظریة النتقال الحرارة ب یصف ھذا البحث دراسة . المحیط معزولین حراریًا و جدار عمودي یواجھ الجانب المفتوح و یحتوي الجزء النشط حراریًا الذي یكون مسخنًا بدرجة حرارة أعلى من درجة حرارة و تم تحویلھا إلى صورة البعدیة مناسبة و من ثم ُفكت دالة الجریان -المعادالت الحاكمة لجریان المائع و انتقال الحرارة داخل الحیز ُمثلت بصیغة الدوامیة و قد ُأعدَّ برنامج حاسوبي خاص تمت صیاغتھ ضمن برمجیة . باستخدام طریقة الفروقات المحددة للوصول إلى معادالت خطیة ُتحل عددیًا بأسلوب اإلرخاء ول على التوزیع الحراري و خطوط السریان خالل الحیز وكذلك رقم نسلتوقد أمكن الحص. الماتالب لتنفیذ النموذج الریاضي المقترح في ھذه الدراسة طول و موضع الجزء عن خط األفق و لقیم مختلفة لدرجة ٦٠-٠بین تراوحتو زوایا میالن ٦١٠٣١٠من أعداد رایلي تراوحت بینالمعدل و لمدى واسع تشیر النتائج التي تم الحصول علیھا إلى إن معدل انتقال الحرارة یكون أعلى عند یكون الجزء النشط في منتصف الجدار العمودي مقارنة . النشط حراریًا زء النشط حراریا في الجدار العمودي یؤدي إلى زیادة عدد رایلي أو زیادة طول الجكذلك إن . ببقیة األوضاع و یقل ھذا المعدل عند زیادة زاویة میالن الحیز .زیادة معدل انتقال الحرارة بالحمل الطبیعي داخل الحیز mailto:jasim_ned@yahoo.com <4d6963726f736f667420576f7264202d20cde3d2c9e6e3cde3cfe6d1c7c6cf34352d203533> al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 14, no. 4, december , (2018) p.p. 4553 the influence of alkaline treatment of recycled natural materials on the properties of epoxy resin composites hamza m. kamal* mohammed j. kadhim** raeid k. mohammed*** *,**,*** department of materials engineering/ college of engineering /al-mustansiriyah university/ baghdad *email: theengineer_1980@yahoo.com ***email: moh_materials@yahoo.com **email: raeid1980@uomustansiriyah.edu.iq (received 7 march 2018; accepted 17 may 2018) 153/kej.2018.05.003https://doi.org/10.22 abstract natural fibers and particles reinforced composites are being broadly used due to their bio and specific properties such as low density and easy to machine and production with low cost. in this work, water absorption and mechanical properties such as tensile strength, flexural strength and impact strength of recycled jute fibers reinforced epoxy resin were enhanced by treating these fibers with alkaline solution. the recycled jute fibers were treated with different concentration of (naoh) solution at (25 0c) for a period of (24) hours. from the obtained results, it was found that all these properties are improved when fibers treated with (7.5wt% naoh) related to untreated fibers. conversely, the mentioned properties of composites decreased after fibers treated with (10wt% naoh). in addition, the hybrid composite with recycled jute fibers and recycled walnut shell powder showed obvious enhancement in the abovementioned properties. keywords: alkaline treatment, composite, epoxy, jute fibers, walnut shell powders. 1. introduction fabricated fibres such as carbon, glass and aramid have been utilized for many years in numerous applications varying from civil structures to aerospace industry. due to the high cost of the materials and manufacturing methods for these man-made fibers, their wider used in several composite applications become limited. therefore, there is a growing interest in the applying of the less expensive natural fibres and particles as reinforcement phase in composites field because of their lightweight, biodegradability, renewability and less health problems for the people producing the composites [1]. the effect of surface treatment of woven jute fabrics with silicone on stiffness and strength properties of vinylester polymer are investigated by basu, it was concluded that all these properties are slightly improved when compared with alkali treated [2]. ratna and coworkers studied the effect of different natural fibers on the properties of polyester resin; it was observed that both of the tensile strength and modulus properties of jowar fibers is higher than those of sisal and bamboo fiber composites in their study [3].the effect of alkali (4-8% by weight) treatment and elevated temperature (40, 80 and 120 0c) on the mechanical properties of the bamboo fiber polyester composites are studied by manalo, it was observed that the best mechanical properties that involved (bending, tensile and compressive strength and the stiffness) are increased by (7, 10, 81 and 25% respectively) higher than the untreated composites at (6%) concentration of the alkaline solution. also the tensile strength of bamboo composites are improved when tested up hamza m. kamal al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 4553 (2018) 46 to 80 0c [4]. libo yan and coworkers studied the effect of alkali treatment on the microstructure and the mechanical properties of coir fibers reinforced polymer and cementitious composites, it was observed that alkali treatment improve the compressive stress and strain, flexural strength and the flexural toughness of coir fiber reinforced cementitious (cfrc) composites due to the improvement in fiber cement interfacial adhesion [5]. the bending behavior of natural sisal fiber reinforced polyester resin are studied with munakaampe, the results show that the prepared composite exhibit better bending properties than the plain polymer matrix [6]. in addition, the impact strength of sisal fibers reinforced polyester is studied by easwara prasad and coworkers; it was found that, the (10) mm long sisal fibers treated for (24) hour is insufficient to improve the impact strength of sisal polyester composites [7]. natural fibers have mechanical and physical properties that differs from fiber to fiber and due to its good mechanical properties such as the specific strength, addition with, non-abrasive, ecofriendly and the biodegradable characteristics, the natural fibers used as an alternative material for artificial fibers reinforced polymer. [8] 2. experimental procedures 2.1. materials the raw materials used in this effort involves the epoxy resin with its hardener triethylene tetramine (teta) as a matrix material and the jute fibers with walnut shell powders which used as a natural reinforcing materials for epoxy resin. 2.1.a. matrix material epoxy resin with its hardener triethylene tetramine (teta) (3:1) ratio (provided from siropol.gp) are used as a matrix material due to its high modulus and strength, excellent chemical resistance, simplicity in processing and commercially available. in addition, the epoxy resins are unique among all thermosetting resins because of several factors including low cure shrinkage, compatibility with a great number of materials, strength and durability, adhesion, corrosion and chemical resistance, and electrical insulation [9]. table (2-1) shows the properties of epoxy resin that used in this work. 2.1.b. reinforcing materials in this work, two types of natural materials are used as reinforcing phases; the first is the jute fibers provided from jute sacks as shown in the (fig.1) with different weight fraction (0, 2.5, 5, 7.5, and 10%) respectively according to the following formula: wf = wf / wc …. (2-1) [10] where (wf) is the weight fraction of fibers, (wf) is the weight of fibers; (wc) is the weight of composite. tables (2-2) and (2-3) show the composition and the mechanical properties of jute fibers. the latter is the walnut shell powder made from crushed walnut shell with (5%) weight fraction. the main reasons from using these natural materials is ascribed to their biodegradable, non-toxic, recyclable, cheap and environmentally safe properties combined with the high tensile properties of the jute fibers related to other natural materials. table 2-1, mechanical properties of epoxy resin mechanical property value glass transition temperature 120 130 °c tensile strength 60-80 mpa tensile modulus 3.5-4 gpa elongation at break 0.8% flexural strength 55-65 mpa compressive strength 170-182 mpa density 1.54 g/cm3 fig.1. jute sacks. table 2-2, chemical composition of jute fibers. [11] hamza m. kamal al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 4553 (2018) 47 table 2-3, mechanical properties of jute fibers. [11] 2.2. alkaline treatment in order to enhance the morphology of the surface and the bonding properties of natural materials with epoxy resin, alkaline treatment are applied to these materials with (7.5% and 10%) of naoh solution for (24 hr.) at ambient temperature. after that, the jute fibers and the walnut shell powders are washed with distilled water (ph=7) at room temperature to eliminate the alkali solution and then dried in oven at 70 oc. fig.2 shows the natural materials that used in this work. (a) (b) fig. 2. walnut shell powders (a), jute fibers (b). 2.3. procedure by means of hand lay-up procedure, composite and hybrid composite materials are prepared in this work, in order to prepare the composite materials, the jute fibers are cut into short fibers with different length (10, 15, and 20 mm) respectively and then mixed with epoxy resin and its hardener for (3) minute with different weight fraction (0, 2.5, 5, 7.5, and 10%) into a plastic cup until obtain a homogeneous mixture and then, the mixture poured into a wood mold for different dimensions according to american society for testing and materials (astm) standards for each required test. the curing time taken by composites was (24) hr. on the other hand, the hybrid composites are prepared by the same approach but by incorporating the best ratio of jute fibers that gives the best mechanical properties with 5% weight fraction of walnut shell powders inside epoxy matrix resin and examine its influences on the above-mentioned properties. 3. characterization in order to determine the required properties, three samples are prepared for each test by cutting the prepared composite and hybrid composite into the required geometry according to the astm standard and applied the procedures of each required test. 3.1. tensile strength measurements the tensile strength is measured based on the astm d3039 [12] specification by the universal testing machine at a strain rate of 10 mm/min. the geometry of the tensile test specimen with (10%) weight fraction of jute fibers before machined shown in the fig.3. (a) (b) fig. 3. tension test geometry according to astm d3039. (a) photo, (b) schematic. hamza m. kamal al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 4553 (2018) 48 3.2. impact measurement the impact strength of the prepared composite determined by the izod impact test according to astm standard d-256 [13]. the geometry of impact test specimen with (10%) weight fraction of jute fibers shown in the fig.4. (a) (b) fig. 4. impact test geometry according to astm standard d-256. (a) photo, (b) schematic. 3.3. flexural strength measurement the flexural strength test is carried out according to the astm d790 [14] by using universal testing machine with span length of (50) mm at the speed to 2mm/min. the geometry of the flexural test specimen with (10%) weight fraction of jute fibers shown in the fig.5. (a) (b) fig. 5. flexural test geometry according to the astm d790. (a) photo, (b) schematic. 3.4. water absorption measurement water absorption measurement is determined by immersing the prepared composite specimens into distilled water at ambient temperature for about (24) hr. after that, the specimens remove from solution and wiped dry to remove the surface moisture. then the specimens are weighted with digital scale in order to calculate the water absorption according to the following formula. water absorption (%) = [(wet weight-sample weight)/sample weight]*100. where wet weight is the weight after immersing and sample weight is the weight before immersing. 3.5. sem characterization sem characterization type (tescan vega ii xmu) is used in this work, which provides highresolution images. separate at least three small samples from each specimen to ensure about homogeneity and unified structure. after that, the samples are cleaned, dried and finally mounted on a stub of metal with adhesive, coated with (40‐60) nm of the gold due to its high conductivity and its relatively small grain size that enables very highresolution imaging. 4. results and discussion the effects of untreated jute fibers with different weight fraction on the tensile, flexural and impact strength of epoxy resin are shown in fig.6, fig.7 and fig.8. it was found from the obtained results, all these properties are slightly enhanced when reinforced with untreated jute fibers and this enhancement increased with increasing the weight fraction of the fibers. hamza m. kamal al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 4553 (2018) 49 fig. 6. tensile strength verses weight fraction of untreated jute fibers. fig. 7. flexural strength verses weight fraction of untreated jute fibers. fig. 8. impact strength verses weight fraction of untreated jute fibers. in order to investigate the behavior of epoxy resin and epoxy-jute fibers composite material, stress-strain curve is necessary for this purpose. fig. 9 shows the stress-strain curve for epoxy resin and epoxy resin reinforced with 10% jute fibers. fig. 9. stress-strain curve for epoxy resin and epoxy resin reinforced with 10% jute fibers. it was observed from the behavior of stressstrain curve in fig.9, the prepared composite composed of epoxy resin with 10% jute fibers exhibit high tensile strength and tensile modulus with high strain when compared with epoxy resin matrix alone. fig. 10. water absorption verses weight fraction of untreated jute fibers. in addition, fig.10 shows the effect of untreated jute fibers on water absorption of epoxy resin when reinforced with the same weight fractions. the results show that, there is an obviously increased in the water absorption of epoxy resin when modified with these natural fibers and this increment increased with increasing the weight fraction of jute fibers. the increment in the water absorption of the prepared composite is ascribed to the "hydrophilic" behavior of the jute fibers, which is mismatched with the "hydrophobic" behavior of polymer resin. this behavior lead to poor resistant to the moisture and high water absorption which result in degradation in the mechanical properties of prepared composite and the interfacial bonding between natural jute fibers and polyester resin as shown in fig.11. hamza m. kamal al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 4553 (2018) 50 fig. 11. degradation in mechanical properties for 10% jute fibers reinforced epoxy resin after water absorption. the results that obtained from fig.11 exhibited the catastrophic effect of the water absorption of these natural fibers on the mechanical properties of epoxy resin by reducing the interfacial bonding between polymer matrix and natural fibers. for these reasons, there is an urgent need to modify the nature of these fibers by using suitable chemical treatment. surface modification with chemical solution is the most common way for overcoming these problems. in this context, the jute fibers and walnut shell powders are treated with alkaline solution of (naoh) with different concentration of (2.5, 5, 7.5 and 10% respectively). the results show obviously enhancement in the mentioned mechanical properties and water absorption when fibers treated with alkaline solution and this enhancement increased with increasing the concentration of solution until (7.5%) of naoh solution related to untreated fibers as shown in the fig.12 and fig.13. the improvement in the properties is attributed to the removal of lignin, waxy materials, and natural oils that covering the outside surface of the fiber cell wall as illustrated in sem image (see fig.14) which lead to surface roughness of the natural fibers and good interfacial bonding between polymer resin and theses fibers. in addition, alkaline treatment improve fibers hydrophobic, interfacial bonding and the wettability of the natural fibers leading to decreasing in the water absorption and enhancement in the mentioned mechanical of properties of composites. on contrary, the results exhibited deteriorated in mechanical properties when fibers treated with (10%) of naoh solution, the reduction in properties is attributed to the high "alkali concentration" which causes an extra elimination of covering materials and "lignin" content that is necessary for bonding the "cellulose fibrils" with each other results in damaging of the fiber surface topography and fiber structure. fig. 12. mechanical properties before and after alkaline treatment. fig. 13. water absorption before and after alkaline treatment. a: before alkaline treatment. hamza m. kamal al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 4553 (2018) 51 b: after alkaline treatment. fig. 14. sem image of jute fibers before and after alkaline treatment. fig.15 and fig.16. show the influence of hybrid composite that composed of (10%) treated jute fibers and (5%) walnut shell powder on the mechanical properties and water absorption of epoxy resin, it was observed from obtained results, there is reasonable improvement in these properties when compared with only (10%) treated jute fibers reinforced epoxy resin plain composite. fig. 15. mechanical properties of the prepared hybrid composite related to plain composite. fig. 16. water absorption of the prepared hybrid composite related to plain composite. the development in the properties is ascribed to the well dispersion of walnut shell powder and jute fibers in matrix as seen in fig.17b related to plain composite (fig.17a) and the compatibility between the natural walnut shell powder and epoxy resin that lead to modify the matrix by inhibiting the crack propagation and enhance the mechanical properties. in addition, the walnut shell powder plays significant role in binding the jute fibers inside the resin matrix and decrease the hydrophilicity of composites that result in reduction in the water absorption properties of epoxy resin. fig. 17. a. sem image of prepared plain composite composed of (10%) treated jute fibers reinforced epoxy resin. fig. 17. b. sem image of prepared hybrid composite composed of (10%) treated jute fibers and (5%) walnut shell powder reinforced epoxy resin. 5. conclusions this effort focused on the preparation of sustainable hybrid composite with minimum cost and environmental pollution by incorporating recycled natural materials in the epoxy resin. in this work, the tensile strength, impact strength, flexural strength and water absorption properties hamza m. kamal al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 4553 (2018) 52 of epoxy resin reinforced by recycled natural materials are studied. the main conclusions can be summarized into the following: 1. the mechanical properties of epoxy resin are slightly enhanced when reinforced with different weight fraction of untreated jute fibers and this enhancement increased with increasing the weight fraction of the fibers until (10%wt) which gives the best mechanical properties. 2. there is an obviously increased in the water absorption of epoxy resin when modified with different weight fraction of the untreated jute fibers and this increment increased with increasing the weight fraction of jute fibers. 3. the results exhibited obviously enhancement in the mentioned mechanical properties and the water absorption properties of epoxy resin reinforced with (10%wt) jute fibers when these fibers treated with (7.5% of naoh alkaline solution) compared with untreated fibers due to the modification in the surface characterization of these natural materials. 4. the high concentration of alkaline solution result in degradation in the above mentionedproperties because of the aggressive influence of high concentration of alkaline solution on the surface topography of jute fibers. 5. the hybrid composite of epoxy resin reinforced with (10%wt) recycled jute fibers and (5%wt) walnut shell powder show reasonable enhancement in the abovementioned properties related to plain composite. 6. references [1] muhammad jannah bin jusoh, "studies on the properties of woven natural fibers reinforced unsaturated polyester composites", msc thesis, 2008. [2] basu,g., samanta, a.k., ghosh, p, "enzyme and silicone treatments on jute fiber" ,part ii. effect on process performance during yarn making and yarn properties. text.inst 99, 307– 316, 2008. [3] a.v. ratna prasad, k. mohana, "mechanical properties of natural fibre reinforced polyester composites: jowar, sisal and bamboo", materials and design 32 (2011) 4658-4663. [4] allan c. manalo, evans wani, noor azwa zukarnain, warna karunasena "effects of alkali treatment and elevated temperature on the mechanical properties of bamboo fiber polyester composites", composites part b 80, (2015) 73e83. [5] libo yan, nawawi chouw, liang huang, bohumil kasal," effect of alkali treatment on microstructure and mechanical properties of coir fibers, coir fiber reinforced polymer composites and reinforced cementitious composites", construction and building materials, 112 (2016) 168–182. [6] grain m. munakaampe, shamitiba b. kanyanga, peter myler, chizyuka g. chizyuka,"response of natural sisal reinforced polyester composites to three-point and fourpoint bending", procedia manufacturing, vol. 7, (2017), 327-332. [7] easwara prasad g l, keerthi gowda b s, velmurugan r, "comparative study of impact strength characteristics of the treated and untreated sisal polyester composite", procedia engineering 173 ( 2017 ) 778 – 785. [8] sanjay m r, arpitha g r, b yogesha, "study on mechanical properties of natural glass fiber reinforced polymer hybrid composites: a review", materials today: proceedings 2 (2015) 2959 – 2967. [9] d. bazrgari, f. moztarzadeh, a.a. sabbaghalvani, "mechanical properties and tribological performance of epoxy/al2o3 nanocomposite", ceramics international, 2017. [10] m.ozgur seydibeyoglu, amar k. mohanty, manjusri misra, "fiber technology for fiber-reinforced composites", woodhead publishing is an imprint of elsevier, 2017. [11] n. chand and m. fahim, "tribology of natural fiber polymer composites", woodhead publishing series in composites science and engineering, 2008. [12] d3039/d3039m, "standard test method for tensile properties of polymer matrix composite materials", american society for testing and materials, volume 15.03, 2015. [13] d256 – 10, "standard test methods for determining the izod pendulum impact resistance of plastics", american society for testing and materials, volume 08.01, 2015. [14] d790 – 10, "standard test methods for flexural properties of unreinforced and reinforced plastics and electrical insulating materials", american society for testing and materials, volume 08.01, 2015. )2018( 4553، صفحة 4، العدد14دجلة الخوارزمي الهندسية المجلم حمزة مصطفى كمال 53 تأثير المعاملة القاعدية للمواد الطبيعية المعادة على خواص متراكبات راتنجات االيبوكسي حمزة مصطفى كمال* محمد جواد كاظم** رائد كاظم محمد*** بغداد/ العراق /الجامعة المستنصرية كلية الهندسة / قسم هندسة المواد/ ***،**،* theengineer_1980@yahoo.com :البريد االلكتروني* moh_materials@yahoo.com :البريد االلكتروني** raeid1980@uomustansiriyah.edu.iq :البريد االلكتروني*** الخالصة التشغيل واإلنتاج المواد المتراكبة المقواة باأللياف والدقائق الطبيعية تستخدم بشكل واسع بسبب خواصها الحيوية والنوعية مثل الكثافة المنخفضة وسهولة ة مثل مقاومة الشد، مقاومة االنحناء ومقاومة الصدمة لراتنج االيبوكسي مع الكلفة المنخفضة. في هذا العمل، قابلية امتصاص الماء والخواص الميكانيكي من محلول المقوى بألياف الجوت المعادة تتحسن عندما يتم معاملة هذه االلياف بمحلول قاعدي. حيث تم معاملة الياف الجوت المعادة بتراكيز مختلفة ) ساعة. من خالل النتائج التي تم الحصول عليها وجد ان كل هذه الخواص تتحسن بصورة ٢٤) مئوية لمدة (٢٥وديوم بدرجة حرارة (هيدروكسيد الص من هيدروكسيد الصوديوم) نسبة لأللياف غير المعاملة. على العكس من ذلك، وجد ان الخواص المذكورة ٧٬٥ملحوظة عند معاملة هذه االلياف ب (% المواد المتراكبة الهجينة المقواة بألياف الجوت المعادة ومسحوق ان ذلك فضال عن ،من هيدروكسيد الصوديوم) %١٠( ـيتم معاملة االلياف ب تتناقص عندما ً قشور الجوز المعادة اظهرت تحسن ً واضح ا في الخواص المذكورة أعاله. ا <4d6963726f736f667420576f7264202d20e3cde3cf20eddadee6c820e6c8d3e3c920e6d3edd3ede1edc73132372d313335> al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 14, no. 1, march, (2018) p.p. 128135 kinetic study of the leaching of iraqi akashat phosphate ore using lactic acid mohammed y. eisa* basma a. abdulmajeed** c. k. haweel*** * department of biochemical engineering/ alkhwarizmi college of engineering/ university of baghdad/ iraq **,*** department of chemical engineering/ college of engineering/ university of baghdad/ iraq *email: mohammedyeisa@yahoo.com (received 18 july 2017; accepted 24 august 2017) https://doi.org/10.22153/kej.2018.08.006 abstract in the present work, a kinetic study was performed to the extraction of phosphate from iraqi akashat phosphate ore using organic acid. leaching was studied using lactic acid for the separation of calcareous materials (mainly calcite). reaction conditions were 2% by weight acid concentration and 5ml/gm of acid volume to ore weight ratio. reaction time was taken in the range 2 to 30 minutes (step 2 minutes) to determine the reaction rate constant k based on the change in calcite concentration. to determine value of activation energy when reaction temperature is varied from 25 to 65�, another investigation was accomplished. through the kinetic data, it was found that selective leaching was controlled by surface chemical reaction. the study showed that the reaction kinetics was specifically described by the shrinking core model (scm). regression analyses gave values of activation energy (ea) and arrhenius constant (ko) as 40.108 kj/mole and (2.256�103 sec-1) respectively. keywords: phosphate ore, organic acid leaching, lactic acid, reaction kinetics. 1. introduction in the mid of nineteenth century, phosphate industry was established through the production of phosphatic fertilizer. gradually, higher purity and more economical phosphates manufactured from elemental phosphorus became available. so the diversity and volume of applications of this product was dramatically preceded. (kirkothmer,1998). the main sources of phosphate in the world are phosphate rocks. mining of these ores provides the required amounts for fertilizers and the other industrial chemicals by chemical processing and beneficiation. these natural resources are neither non-renewable nor substitutable. approximately 75-80% of the phosphate ores are classified as sedimentary, 15-20% are igneous and only 1-2% are from biological origin. (straaten, 2002; guimarães et al., 2005). approximately, there are 200 known types of minerals contain more than 1% p2o5. apatite is the most important ore used for the phosphate and phosphoric acid industry (becker, 1983; gremillion and mcclellan, 1975). in iraq, the most important formation is akashat phosphate which contains approximately 21-22% of phosphorus pentoxide. this ratio can be increased to about 25% using simple physical methods. these deposits appear in sedimentary layers accompanied with limestone and clay. francolite apatite ca10(po4)6f2 is the main metal component of these ores associated with calcite (shirqi and tawfiq, 2010). phosphate, produced by mining, contains other minerals. only apatite mineral is needed for phosphoric acid manufacture. the other minerals must to be removed by beneficiation. first the raw phosphate is washed by water to remove the soluble impurities. it is necessary to remove the carbonate and siliceous impurities to avoid problems in the manufacture of phosphoric acid. mohammed y. eisa al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 128135 (2018) mohammed y 129 the siliceous impurities consist of tiny particles, which cause problems in the filtration stage. the removal of carbonate content is so essential before the digestion of the phosphate rock in the inorganic acid. in contrast, excessive foaming occurs due to the formation of carbon dioxide in this stage (rao et al., 1992; sluis, 1987). usually, the p2o5 content in the marketable phosphate ore is about 28-36% and 35-39% for the sedimentary and igneous types respectively. in order to be economical, carbonate content should not exceed 8% in phosphate ores (gharabaghi et al., 2009). in the fertilizer industry, phosphate ores must have more than 30% p2o5 content. depending on the particle size of phosphate, mineral impurities content and other specifications, effective beneficiation is achieved using different approaches, (heidarpour, 2009). in addition, the presence of carbonates in the phosphate rocks requires more sulfuric acid during the manufacture of superphosphates and phosphoric acid using the wet process. in the other hand, the formed carbon dioxide through addition of acid causes the production of smaller size crystals of gypsum that may blind the phosphor gypsum filters leading to production of a low quality phosphoric acid (malash, 2005). a worldwide problem is the beneficiation of sedimentary phosphate ores containing carbonate impurities and there is no adequate method to treat such ores on an industrial scale. however, calcination is utilized (abouzeid, 2008). calcination use is limited in areas where low cost energy and water resources are abundant. as any other method with a negative attitude, the calcined phosphate has a lower quality concerning the reactivity and surface properties (ozer, 2003). chemical dissolution of carbonate minerals (calcite and dolomite) from calcareous phosphate ores, without calcination, using organic acids also proved capable of upgrading the calcareous phosphate ores on the laboratory scale. with regard to the problems with sedimentary phosphate ores, acid leaching is a promising method that can be applied to treat the calcareous phosphate ores and more attention being given to leaching methods. since nearly 80% of the world's phosphate resources are calcareous ores (gharabaghi et al., 2009). studies on the separation of carbonate ores by organic acids are limited. however, the results showed the effectiveness of acetic acid, lactic acid, formic acid and succinic acid for leaching of calcareous phosphate ores. many of the problems occurred through the production of phosphoric acid and superphosphates are treated using this leaching technique. both magnesium and calcium carbonates are removed efficiently using this approach with small time of reaction and so minimum destructive effects (bilgic 2002). for instance, equation (1) shows the reaction of lactic acid with carbonate minerals for dissolution (gharabaghi et al., 2010): caco�(�) + ch�ch(oh)cooh(� ) = ca(ch�ch(oh)coo)�(� ) + co�(� ) + h�o(�) … (1) due to the removal of co2 produced during the reaction, this process may be considered as an irreversible. in order to understand the process of selective leaching, the simplest mechanism for the reaction can be shown as follows (zafar and ashraf, 2007): mco�(�) + 2hx(� ) → mx�(� ) + co�(�) + h�o(�) ...(2) m�(po�)�(�) + 6hx(� ) → 3mx�(� ) + 2h�po�(� ) …(3) where: m=ca+2 and/or mg+2, and x=ch3ch(oh)coo− (lactate). to avoid the dissolution of phosphate mineral by the organic acid, reaction (3) should not takes place while reaction (2) proceeds to completion. reactions of formic and succinic acid are similar to lactic and acetic acid. in this case, succinate and formate can be substituted with x in equations (1) and (2) taking into account the stoicheometric consideration (gharabaghi et al., 2010). in a previous work (haweel c.k. et al., 2013), leaching process was studied using two organic acids (acetic acid and lactic acid) to beneficiate phosphate from iraqi akashat phosphate ore. the obtained experimental data of x-ray diffraction (xrd) and fourier transform infra red (ftir) showed that lactic acid is more efficient than acetic acid as shown in figures (1) to (4). comparing the spectrum of figures (1) and (2) show a decrease in calcite content at 2�=29o and an increase in phosphate content at 2�=32o. the same conclusion is found in figures (3) and (4) where the ftir absorbencies of calcite is decreased near 1430 cm-1 while phosphate absorbencies increased near 1050 cm-1 wave number to assure the xrd results. mohammed y. eisa al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 128135 (2018) mohammed y 130 fig. 1. xrd spectra of raw akashat phosphate ore size 300 micron. fig. 2. xrd spectra of beneficiated akashat phosphate ore size 300 micron using lactic acid leaching. fig. 3. ftir spectra of raw akashat phosphate ore size 300 micron. fig.4. ftir spectra of beneficiated akashat phosphate ore size 300 micron using lactic acid leaching. in relating to the volume of acid to ore weight ratio, the investigation shows that reducing this ratio to 5 ml/gm enhances the purity of apatite at the optimum acid concentration (haweel, c.k. et. al., 2013). 2. kinetics of chemical reaction in the type of heterogeneous reactions, where a fluid is in contact with a solid, reaction takes place and gives product. three cases fluid, solid or fluid and solid mixture products are expected. as shown in figure (5), when the solid particles contain large amounts of impurities they remain unchanged in size during reaction as a nonflaking ash. in the other hand, when a flaking ash is formed or when pure solid reactant is used, the reaction particles shrink in size during reaction. fig. 5. different sorts of behavior of reacting solid particle (cussler, 2007). regarding mass transfer and reaction kinetics a number of models are available for the dissolution of solid particles with the surrounding fluid (hem, 1993). it is necessary to be understood that every conceptual model for the progress of reaction comes with its mathematical model and rate equation. if a model corresponds closely to what really occurs, then its rate expression will preciously fit the suitable kinetics; if a model differs from reality, then its kinetic models will be useless. for noncatalytic reaction of particles with surrounding fluid, the progressive conversion model (pcm) and the unreacted core (shrinking core) model (scm) may be considered. when a fluid reacts with the solid particle at a constant rate, the progressive conversion model 40060080010001200140016001800200024002800320036004000 1/cm -0 0.25 0.5 0.75 1 1.25 1.5 1.75 2 2.25 2.5 2.75 3 3.25 3.5 abs 1 5 0 6 .4 7 1 4 5 7 .2 8 1 4 3 0 .2 8 1 4 2 3 .5 3 1 4 1 9 .6 7 1 0 9 3 .6 9 1 0 5 5 .1 1 1 0 4 4 .5 0 1 0 3 9 .6 8 1 0 3 3 .8 9 6 0 5 .6 7 5 7 8 .6 7 5 6 9 .9 9 ftir measurement mohammed y. eisa al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 128135 (2018) mohammed y 131 (pcm) may be fit. thus, solid reactant is converted continuously throughout the particle and progressively. in the shrinking core model (scm), it is found that reaction occurs first at the particle surface. the reaction part then moves into the solid, leaving completely converted material and the ash. thus, continuously, an unreacted core of material exists shrinking in size as the reaction proceeds. however, the unreacted core model seems to reasonably represent reality more closely in most cases than does the progressive conversion model (octave, 1999). the shrinking core model of unchanging size particle was first developed by (yagi, 1955). five steps were suggested to be occurred during reaction: 1. diffusion of fluid reactant through the outer film to the surface of the solid particle. 2. penetration through the ash to the inner unreacted core. 3. chemical reaction of fluid with solid at the reaction surface. 4. fluid products diffusion through the ash to the solid outer surface. 5. fluid products diffusion through the gas film returning to the bulk of fluid. in many cases some of these steps do not exist. in such cases it may be considered that the lowest step to be rate-controlling (kunii, 1991). in this treatment, the rate equations for spherical particles are shown below: for film diffusion control: � � = 1 − "#$ % & � = x' ...(4) for chemically controlled process: � � = 1 − #$ % = 1 − (1 − x')(/� ...(5) for product layer diffusion control: � � = 1 − 3(1 − x')�/� + 2(1 − x') ...(6) where: * is the time for complete conversion of a particle. xa is the conversion of calcareous material after time t. r is the radius of the particle. rc is the radius of the particle core. these rate expressions were used to test the validity and best fit to the experimental data as shown in the next sections (octave, 1999). an investigation is to be conducted to specify the type of kinetic model which fit to the selective leaching of iraqi akashat phosphate ore using lactic acid and to calculate arrhenius equation parameters. 3. experimental work in order to specify the kinetic behavior of the reactants and the rate of reaction control step, a set of experiments was performed to study the change in fractional conversion of calcite (xa) with time. for selective leaching studies, (-0.125+0.30 mm) size fractions of akashat phosphate ore were used as the source of phosphate. sample was added to a well mixed three necked funnel glass batch reactor of (500 ml) size, equipped on a magnetic stirrer having a controller unit. a known amount of lactic acid 10 % by weight concentration with the liquid to solid (l/s=5) volume ratio was slowly pipetted into the reactor vessel containing 5.0g of the sample for a specific time each run according to the set of experiments shown in table 1. table 1, loi data of phosphate ore leaching using lactic acid at the operating conditions (10wt%, l/s=5) no. time (sec.) (loi) % calcite wt.% conversion (xa) 1 0 21.6172 49.13 0 2 120 19.1884 43.61 0.11 3 240 17.3558 39.445 0.195 4 360 15.3076 34.79 0.29 5 480 13.4103 30.478 0.378 6 600 12.1383 27.587 0.437 7 720 10.5644 24.01 0.51 8 840 9.2708 21.07 0.57 9 960 7.9772 18.13 0.63 10 1080 6.8345 15.533 0.683 11 1200 6.1446 13.965 0.715 12 1320 5.6056 12.74 0.74 13 1440 4.9588 11.27 0.77 14 1560 4.4629 10.143 0.793 15 1680 3.9670 9.016 0.816 16 1800 3.9670 9.016 0.816 acid concentration is calibrated using ph meter. temperature for all experiments fixed under control (30�). mixing speed at 300 rpm to ensure steady dispersion of particles in the liquid phase. reaction time was taken in the range 2 to 30 minutes (step 2 minutes) to determine the rate of reaction constant k based on the change in calcite concentration. at the end of each run, mixing was immediately stopped to end the reaction. the leaching slurry is then separated using vacuum filtration. the resulting filtrates were then dried, weighed and analyzed by loss on ignition (loi) by mohammed y. eisa al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 128135 (2018) mohammed y 132 calcination at 900� using muffle furnace (nabertherm-n20/h-west germany) to investigate the change in reactant (calcite) concentration with time as shown in table 1. +,-% = /01/2 /0 � 100% ...(7) where: wo=initial weight of phosphate (g) before calcination wi=final weight of phosphate after leaching (g) after calcination the difference in weight by calcination of beneficiated phosphate ore gives the calcite content which decreased with time according to the observed data of table 1. 4. results and discussion after the reaction completion, it was found that the final particles are hard, firm and unchanging in size. therefore the shrinking particle model with changing size was not properly working in the present case. keeping in view that the shrinking core model (scm) may be considered to appropriately work regarding this dissolution behavior. in order to specify the rate controlling step of the specified model, figure 7 is plotted to show the effect of reaction time on the fractional conversion of reactant based on data of table 2. three cases of reaction rate control were plotted supported by statistical analysis to test the validity of the experimental data using equations 4, 5 and 6 for the fluid layer diffusion, ash layer diffusion and chemical reaction control respectively. values of correlation coefficients determination for these rate expressions were compared. fig. 6. effect of reaction time on xa, 1-(1-xa)1/3, 13(1-xa)2/3+2(1-xa) from the regression analysis and figure 6, it was found that just one of the plots gives a straight line which is fit to the model of chemical reaction control, i.e. that the best value of correlation coefficient promising the rate expression was for chemical reaction control and its value was calculated as 0.999. so, it was found that this reaction was controlled by chemical reaction according to the expression [1-(1-xa)1/3=kt] of equation 5. value of reaction rate constant in return to this regression is (2.51�10-4 sec-1). in a relevant study by (zafar and ashraf, 2007), the kinetic data of leaching of another type of calcareous phosphate rock in lactic acid was analyzed by graphical and statistical methods, showed that the leaching was controlled by chemical reaction. the obtained results by the present work also confirm other earlier reported results (economou and vaimakis, 1997; fairchild et al., 1999). table 2, kinetic data of phosphate ore leaching using lactic acid at the operating conditions (10wt%, l/s=5) no time (sec.) conv. (xa) 1-(1-xa)1/3 1-3(1-xa)2/3+2(1-xa) 1 0 0 0 0 2 120 0.11 0.0381 0.0042 3 240 0.195 0.0698 0.0139 4 360 0.29 0.1079 0.0324 5 480 0.378 0.1464 0.0580 6 600 0.437 0.1743 0.0805 7 720 0.51 0.2116 0.1154 8 840 0.57 0.2452 0.1509 9 960 0.63 0.2821 0.1938 10 1080 0.683 0.3182 0.2393 11 1200 0.715 0.3419 0.2708 12 1320 0.74 0.3617 0.2979 13 1440 0.77 0.3873 0.3338 14 1560 0.793 0.4085 0.3642 15 1680 0.816 0.4312 0.3975 16 1800 0.816 0.4312 0.3975 5. activation energy activation energy can be calculated using arrhenius equation (8). a set of experiments relates temperature in the range (25-65�) with the reactant conversion based on the loss on ignition test loi at the best reaction conditions using lactic acid were applied, as shown in table 3. a plot is drown according to the data calculations shown in table 3 of ln k versus 1/t in order to correlate values of arrhenius equation parameters. a straight line was resulted with a slop of (-ea/r) and an intercept of (ln ko) as shown in figure 7. mohammed y. eisa al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 128135 (2018) mohammed y 133 from this figure and a regression analysis with correlation coefficient (0.9747), value of activation energy (ea) was calculated as 40.108 kj/mole and arrhenius constant (ko) was (2.256�103 sec-1). through the obtained results, it was found that selective leaching of akashat phosphate ore using lactic acid was controlled by surface chemical reaction. so the shrinking core model equation 8 can be used to describe the reaction kinetics: 1 − (1 − 45)(/� = 6 7889: ;< = > = ?@> = 1.354 � 10�exp (−40108/gh). > ...(8) parameters of equation 8 are detailed below: i is the stoichiometric ratio of the solid reactant b ?jj is the 1st order rate constant for the surface reaction k5 is the concentration of the fluid reactant (mol/lit)a lm is the molar density of solid reactant (mol/m3) table 3, experimental data of arrhenius equation parameters no t ok xa k=(1-(1xa)1/3)/t ln k 1/t 1 298 0.806 0.4216 -8.3592 0.00335 2 308 0.847 0.4655 -8.0370 0.00325 3 318 0.86 0.4807 -7.4658 0.00314 4 328 0.926 0.5802 -7.1237 0.00305 5 338 0.932 0.5918 -6.4106 0.00296 fig. 7.arrhenius plot using lactic acid at reaction conditions (acid concentration=10 wt%, l/s=5 ml/g). 6. conclusions 1. in the end of leaching reaction, it was found that the final particles are hard, firm and unchanging in size. therefore the shrinking core model (scm) can be considered appropriately fit regarding this dissolution behavior. 2. from correlation coefficient values of the regression for the rate expressions it was found that the leaching was controlled by chemical reaction and value of reaction rate constant in return to this regression was (2.51�10-4 sec-1). this value indicate that the reaction rate is highly dependent on the initial concentration of reactant (lactic acid). 3. regression analysis of the experimental data with arrhenius equation fitted with correlation coefficient (0.9747) giving 40.108 kj/mole for the activation energy (ea) and arrhenius constant (ko) was (2.256�103 sec-1). these results show that the reaction rate constant is highly affected by the temperature variation. in another words, increasing the temperature by 50� cause an increase in the reaction rate constant value by 10 times. acknowledgments the authors like to express high appreciation and thanks to the: • chemical engineering department, college of engineering, university of baghdad. • central environmental laboratory, college of science, university of baghdad. • construction national center for construction laboratories and research, ministry of construction and housing. for providing facilities to complete the chemical tests required by this research. 7. references [1] abouzeid, a.z., 2008. “physical and thermal treatment of phosphate ores-an overview”. int. j. miner. process. 85, pp. 59–84. 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[13] kunii, d., and levenspiel, o., 1991. “fluidization engineering, 2nd ed”, butterworth, boston, ma, usa. [14] malash, g.f., 2005. “beneficiation of abu tartur phosphate rock by leaching with dilute acetic acid solution”, alexandria engineering journal, 44, 2, pp.339–345. [15] octave, l., 1999. “chemical reaction engineering, 3d edition”. john wiley & sons, new york, usa. [16] ozer, a.k., 2003. “the characteristics of phosphate rock in a fluidized bed for the upgrading”. advanced powder technology, 14, 1, pp.33-42. [17] rao, t.c., rao, l.s. and rao, g.m., 1992. “beneficiation of indian low grade phosphate deposits: problems and prospects”, transactions of the indian institute of metals, 45, 3, pp.195–205. [18] sluis, van der, 1987. “a clean technology phosphoric acid process”. ph.d. thesis, delft university press, netherlands. [19] straaten, p.v., 2002. “rocks for crops, agro minerals of sub-sahara africa”. nairobi, kenya, pp.7-24. [20] yagi, s., and kunii, d., 1955, 5th symposium (international) on combustion, reinhold, new york; chem. eng. (japan), 19, 500, pp.231. [21] zafar, z.i. and ashraf, m., 2007. “selective leaching kinetics of calcareous phosphate rock in lactic acid”, chemical engineering journal, 131, pp.41-48. m 2018( 128-135 ، صفحة1د، العد14دجلة الخوارزمي الهندسية المجلم محمد يعقوب عيسى( 135 العراقي باستخدام حمض اللبنيكدراسة حركية استخالص خام فوسفات عكاشات سيسيليا خوشابا هاويل** بسمة عباس عبد المجيد** محمد يعقوب عيسى* / جامعة بغدادالهندسة الخوارزمي* قسم الهندسة الكيميائية األحيائية/ كلية ية/ كلية الهندسة / جامعة بغداداو**،*** قسم الهندسة الكيمي mohammedyeisa@yahoo.com*البريد االلكتروني: الخالصة: في هذا البحث تم إجراء دراسة حركية ألستخالص الفوسفات من خام فوسفات عكاشات العراقي باستخدام حامض عضوي. تم دراسة عملية مل/غم من نسبة حجم الحامض ٥نسبة وزنية من تركيز الحامض و ٪٢االستخالص باستخدام حمض اللبنيك لفصل المواد الكلسية. وكانت ظروف التفاعل استنادا إلى التغير في تركيز kدقيقة) لتحديد قيمة ثابت سرعة التفاعل ٢دقيقة (الخطوة ٣٠إلى ٢م. تم دراسة زمن التفاعل في المدى من إلى وزن خا الحركية، درجة مئوية. من خالل البيانات ٦٥إلى ٢٥الكالسايت. تم ايضا اجراء دراسة لتحديد قيمة طاقة التنشيط عند درجات حرارة التفاعل للمدى من ه التحديد وجد أن الخطوة المسيطرة على تفاعل االستخالص االنتقائي هو التفاعل الكيميائي السطحي. وأظهرت الدراسة أن حركية التفاعل وصفت على وج × ٢٫٢٥٦كيلو جول / مول و ( ٤٠٫١٠٨) بقيم ok) وثابت أرهينيوس (aeمن قبل نموذج األساسية تقلص (سم). أعطى تحليل االنحدار قيم طاقة التنشيط ( ) على التوالي.١-ثانية ١٠٣ د اميل ومحمد عطية ومها al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 111 (2013) enhancement of iraqi light naphtha octane number using pt supported hmor zeolite catalyst mohammed a. atiya* ameel mohammed rahman** maha h. al-hassani*** * research and development directorate / ministry of higher education and scientific research **department of biochemical engineering / al-khawarizmi college of engineering / university of baghdad ***department of chemical engineering / college of engineering / university of baghdad *email:mohatiya1955@gmail.com **email:explorerxp50@yahoo.com ***email:alhassani_maha@yahoo.com (received 5 september 2013; accepted 3 december 2013) abstract the hydroconversion of iraqi light straight run naphtha was studied on zeolite catalyst. 0.3wt.%pt/hmor catalyst was prepared locally and used in the present work. the hydroconversion performed on a continuous fixed-bed laboratory reaction unit. experiments were performed in the temperature range of 200 to 350°c, pressure range of 3 to 15 bars, lhsv range of 0.5-2.5h-1, and the hydrogen to naphtha ratio of 300. the results show that the hydroconversion of iraqi light straight naphtha increases with increase in reaction temperature and decreases with increase in lhsv. high octane number isomers were formed at low temperature of 240°c. the selectivity of hydroisomerization improved by increasing reaction pressure up to 15 bars. catalyst activity almost stable and independent of time on stream at 15 bar up to 20 h. keywords: hydroisomerization, light naphtha, zeolite, octane number, mordenite. 1. introduction with the continuously increasing environmental concerns and stringent regulations on the utilization of gasoline as an automotive fuel, there is a great need to search for alternative gasoline octane number enhancers. currently, various additives are available for gasoline octane number enhancement e.g. oxygenate and aromatic compounds (alexander et al., 2013; sandeep et al., 2013; liu et al., 2011; nikolaou et al., 2004; chao et al., 1996). these compounds are considered as environment harmful compounds. finding a harmless substituent to the high-octane oxygenates and aromatics is not a straightforward task, since main octane enhancers have either been completely phased out due to their toxicity in many countries worldwide, such as in the case of lead-containing additives, or seen their use decline due to their environmental problems, like oxygenates such as mtbe (methyl t-butyl ether). in addition, using octane-rich reformates fails to do the trick since aromatics are a major constituent of them (busto et al., 2012; chiang et al., 2011; chao et al., 2000). however, the utilization of an upgraded low-value refinery stream to the gasoline pool might present a solution to the problem, as it can considerably lower the cost of gasoline production, while losing only some of its original quality, but still remain environmentally friendly. it is a promising objective to produce high octane number gasoline from petroleum sources. the requirements to reduce these additives in mohammed abd atiya al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 111 (2013) 2 gasoline present a need to find an alternative way to maintain its research octane number (ron). an alternative way is to increase the ron for the paraffinic content of gasoline, which can be accomplished through hydroisomerization. light paraffin hydroisomerization has been used provide a cost-effective solution to manage benzene in motor fuels (stanislav et al., 2012, raed et al., 2010; liu et al., 2009; theo et al., 2008). the process of light naphtha hydroisomerization involves the transformation of normal paraffins (i.e. normal c5-c7 fraction which is the main constituent) into their isomers, which have higher octane numbers than the normal paraffins over acidic catalysts (sege et al., 2003; gauw et al., 2002; lee et al., 1997; guisnet et al., 1991). mechanically, hydroisomerization occurs in three elementary steps. first, the alkane is dehydrogenated. then generated alkene adsorbs on a brønsted acid site, forming an alkoxy group (a carbenium ion in the transition state), which isomerizes and eventually desorbs. finally, the iso-olefin is hydrogenated to iso-alkane. therefore, catalysts are bifunctional, with a metal (pt, pd) catalyzing the hydrogenation/ dehydrogenation step and an acidic function for the formation and isomerization of the alkoxy group/ carbenium ion. the metal component also helps reduce catalyst deactivation by hydrogenation coke precursors (gauw et al., 2002; hollo et al., 2002; aboul-gheit et al., 1998; allian et al., 1997). as the reaction proceeds via carbenium ions, other brønsted acid catalyzed reactions, as oligomerization and cracking compete with isomerization (gauw et al., 2002; hollo et al., 2002). in addition, side reactions on the metal, as hydrogenolysis of the alkane to smaller alkanes, may reduce the selectivity of the overall hydroisomerization reaction (gauw et al., 2002; hollo et al., 2002). in the present study, pt supported hmor zeolite catalyst is prepared locally and used to hydroisomerize iraqi light straight run naphtha (lsrn). the main objective in this work is to develop a useful catalyst and optimize the limited ranges of operating conditions (temperature, lhsv, and operating pressure) on the naphtha transformation and octane number in a fixed bed continuous laboratory reaction unit. catalyst stability is also highlighted. 2. experimental work 2.1. materials 2.1.1. feedstock light straight run naphtha (lsrn) supplied from al-dura refinery was used as a feedstock in hydroisomerization experiments. the properties of lsrn are listed in table. 1 table 1, properties of straight run light naphtha. api @ 60°/60°f 78.6 octane number 61.4 sulfur content < 2ppm kinematic viscosity at 25℃ 7.2×10-7 m2/s composition wt.% propane 0.01 i-butane 3.19 n-butane 4.27 i-pentane 33.46 n-pentane 21.57 cyclo-pentane 0.94 i-hexane 6 n-hexane 15.27 cyclo-hexane 4.1 i-heptane 2.5 n-heptane 4.58 iand n-octane 1.37 benzene 0.76 toluene 0.95 xylene 0.16 naphthalene c8 0.2 naphthene c8 0.39 naphthene c9 0.28 mohammed abd atiya al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 111 (2013) 3 2.1.2. hydrogen and nitrogen gases high purity (99.999 vol. %) of hydrogen and nitrogen gases supplied from the local market were used in the present work. 2.1.3. ammonium mordenite zeolite ammonium mordenite zeolite (cbv-21a) supplied as a powder from zeolyst international company. it was used in the preparation of the proposed catalyst. the properties of this zeolite are listed in table 2. table 2, properties of ammonium mordenite zeolite powder (cbv-21a). sio2/al2o3 mole ratio nominal cation form na2o weight % surface area, m2/g 20 ammonium 0.08 500 2.1.4. hexachloroplatinic acid hexachloroplatinic acid (h2ptclo6.6h2o) of an analytical grad (40 wt.% pt) was supplied by fluka chemi ag. 2.2. catalyst preparation 100 g of ammonium mordenite (cbv-21a) powder was shaped as a pelletes with 3mm×5mm using a laboratory scale pelleting machine (model tdp-1.5 from minhua pharmaceutical machinery co., limited). the final form was dried at 110°c and stored in an evacuated place. 2.3. 0.3 wt.%pt/ hmor zeolite preparation 0.3wt%pt on hmor zeolite was prepared by impregnation method. hmor pellets were dried over night at 110°c and impregnated with 0.3 g of h2ptclo6.6h2o in 10 ml deionized water. the final impregnated pellets were dried at 110°c over night and calcinated at 300°c for 3 hrs in a furnace with dry air. the calcinated catalyst pellets were then reduced with hydrogen at 350°c for 3 hrs (al-hassani, 2007). the properties of the prepared catalyst are listed in table 3. table 3, properties of the 0.3wt%pt/hmor zeolite. surface area m2/g 662 bulk density g/cm3 0.592 pore volume, cm3/g 0.143 2.4. hydroisomerization reaction unit hydroisomerization experiments were conducted in a continuous fixed bed reactor laboratory scale unit. figure 1 shows the schematic diagram of this unit. it consist of feed tank (t-301), gas flow meter and controller (fcv), feed pump (p-301), evaporator (m-301), fixed bed reactor (r-301), high pressure separator (e-301), low pressure separator (s-301), and an appropriate heating system (h-301). the reactor was heated and controlled automatically with computer control software and by four steel jacket heaters using chromal alumel thermocouple (type k). 2.5. hydroisomerization experiments 30 cm3 of fresh catalyst was charged to the reactor and between two layers of inert material (glass balls). in the beginning of each experiment, the reactor was flashed with nitrogen 2 l/h for 1 h to purge the air from the system, then the reactor is heated to the desired temperature. when reactor temperature is reached, the nitrogen valve is closed. a pre-specified flow rate of light naphtha was set on, vaporized in the evaporator and the vapor was mixed with the hydrogen in the mixing unit at a specified flow rates. the mixture entered the reactor from the top, distributed uniformly and reacted on the catalyst. the gaseous products passed through the high pressure separator and the final condensates were collected in the low pressure separator only after steady state operation was established and the initial products were discarded. the hydroisomerization reaction conditions employed are temperature range 200350°c, liquid hourly space velocity (lhvs) range 0.5-2.5h-1, hydrogen to light naphtha volumetric ratio 300 and the pressure was ranging from 315bar. mohammed abd atiya al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 111 (2013) 4 r-301 tubular reactor p-301 feed pump fcv-301 fcv-302 fcv-303 fcv-304 mass flow controller t-301 feed tank e-301 condenser s-301 separator m-301 mixer h-301 heater prv-301 pressure relief valve piping and instrument flow diagram laboratory reaction unit university of baghdad al-khawarizmi college of engineering department of biochemical engineering fig. 1. schematic diagram of laboratory continuous fixed bed reaction unit. mohammed abd atiya al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 111 (2013) 5 2.6. analysis 2.6.1. atomic absorption analysis the analysis of platinum, in the prepared catalyst, was achieved using atomic absorption spectrophotometer (model pye-unicam sp9) in ibn sina state company. 2.6.2. gas chromatographic analysis the collected products (liquid and gas) were analysis into their components by gas chromatographic (gc) analysis using shimadzu gc model 2014a with fid detector. 2.6.3. octane number test this test was achieved in dura refinery using ron method (astm -d 2699). 3. results and discussion the results of hydroconversion runs of iraqi lsrn are discussed in this section in order to evaluate the catalyst performance. the purpose of the present work is to choose the optimal experimental conditions that most satisfy high catalyst stability and product octane number. the hydroconversion involve three main reactions hydroisomerization, hydrocracking, and hydrocycalization and aromatization. in this section, discussions were built upon the results of these reactions. 3.1. effect of temperature the effect of temperature on lsrn transformation is shown in figs. 2-4. it is clearly temperature dependent; in fact, in the temperature range of 473 to 513k the hydroconversion shifted towards the hydroisomerization conversion and as shown in fig. 3, while above 513 the isomers formation decreases and the reaction is shifted towards the hydrocracking, hydrocycalization aromatization reactions and as shown in figs. 2 to 4. this means that the formation of isomers is favored at lower temperature and this phenomenon is further explained by fig. 5. the octane number of n-hexane is around 25, npentane is around 62, the mp isomer is around 75 and dmb is around 95, furthermore, the lower reaction temperature, the greater the percentage of branched alkane at thermodynamic equilibrium, hence the higher the octane number (sege, 2003; gauw et al., 2002; grillo et al., 1997). 40 50 60 70 80 90 100 110 440 490 540 590 640 temperature, k w t. % fig. 2. isomers formation percent vs. temperature at lhsv of 0.5h-1 and pressure of 15bar. 0 1 2 3 4 5 6 7 8 9 440 490 540 590 640 temperature, k w t. % fig. 3. hydrocracking products formation percent vs. temperature at lhsv of 0.5h-1 and pressure of 15bar. 0 0.5 1 1.5 2 2.5 3 3.5 440 490 540 590 640 temperature, k w t. % fig. 4. percent of hydrocyclization and aromatization products vs. temperature at lhsv of 0.5h-1 and pressure of 15bar. mohammed abd atiya al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 111 (2013) 6 70 75 80 85 90 95 450 470 490 510 530 550 570 590 610 630 650 temperature, k r o n fig. 5. effect of temperature on the ron at lhsv of 0.5 h-1 and pressure of 15bar. 3.2. effect of contact time figures 6 to 8 show the change in lsrn transformation as a function of contact time. the contact time is expressed as the reverse of lhsv, the liquid hourly space velocity taken as the ratio between the volumetric flow rate of lsrn and catalyst volume. it can be observed from these figures that as the contact time increases the hydroconversion increases so the rates of hydroisomerization, cracking and hydrocycalization and aromatization increases. also isomers are formed at low contact times (i.e. low conversion), a small amount of cracking products appearing at higher contact times. a high increase in ron number was observed with the increase in contact time and as shown in fig. 9. this increases many be attributed to the formation of high octane number isomers and as explained above. the same observations were reported in other works (busto et al., 2012; jiménez et al., 2003; partylak et al., 1998; allian et al., 1997). 0 10 20 30 40 50 60 70 80 90 0 0.5 1 1.5 2 2.5 3 1/lhsv, h w t.% fig. 6. isomers formation percent vs. lhsv at temperature of 553k and pressure of 15bar. 0 1 2 3 4 5 6 0 0.5 1 1.5 2 2.5 3 1/lhsv, h w t.% fig. 7. hydrocracking products formation percent vs. lhsv at temperature of 553k and pressure of 15bar. 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 0 0.5 1 1.5 2 2.5 3 1/lhsv, h w t. % fig. 8. percent of hydrocyclization and aromatization products vs. lhsv at temperature of 553k and pressure of 15bar. mohammed abd atiya al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 111 (2013) 7 40 50 60 70 80 90 100 0 0.5 1 1.5 2 2.5 3 1/lhsv, h r o n fig. 9. effect of contact time on ron at temperature of 553k and pressure of 15bar. 3.3. effect of pressure the effect of pressure on the iraqi lsrn reaction selectivities and ron are shown in figs. 10, 11, and 12. as the operating pressure increases the selectivity of hydroisomerization increases and the selectivity of hydrocracking decreases rapidly while the selectivity of hydrocyclization and aromatization slightly increases. the increase in operating pressure is probably leads to a decrease in alkenes formation, in turn, diminish the probability to proceeds the dimerization cracking and provide higher isomerization selectivity as shown in fig. 10. as a results ron increases rapidly with the increases in the operating pressure and up to 15bar, after this value ron unaffected by the change in operating pressure. the reaction of alkane transformation proceeds with the skeletal hydroisomerization via bimolecular mechanism. abuda wood et al.; 2010, showed that the hydrogenation activity increased at a higher hydrogen pressure that results in the hydrogenation of more intermediate olefins, which can be due to a shorter intermediate olefin residence time inside the catalyst, and thus minimizing the cracking activity. these observations are agree well with the results reported by gauw et al., (2002), liu et al., (1997), chao et al., (1996) and guisnet et al., (1991); chao et al., 2000. 86 88 90 92 94 96 98 100 0 5 10 15 20 25 pressure, (bar) s el ec ti vi ty , ( w t. % ) fig. 10. hydroisomerization selectivity vs. operating pressure at lhsv of 1h-1 and temperature of 553k. 0 2 4 6 8 10 12 14 0 5 10 15 20 pressure, (bar) s el ec tiv it y, ( w t. % ) hydrocracking hydrocycalization and aromatization fig. 11. hydrocracking, hydrocycalization and aromatization selectivities vs. operating pressure at lhsv of 1h-1 and temperature of 553k. 40 50 60 70 80 90 100 0 5 10 15 20 25 pressure, (bar) r o n fig. 12. effect of operating pressure on ron at lhsv of 1h-1 and temperature of 553k. mohammed abd atiya al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 111 (2013) 8 3.4. catalyst stability and time on stream the stability during the reaction of zeolite catalysts is measured by time on stream. it can be observed from fig. 13 that the present 0.3wt.%pt/hmor catalyst is very stable with almost no (i.e. very slight change) change in activity when tested for 20 hours. unfortunately, this stability is in the expense of hydroisomerization activity towards high octane numbers isomers. this is partly due to a very slow coking that may have poisoned the acid sites on the catalyst and changed the effective amount of acid sites density on the catalyst needed. these results are agree well with other observation reported by stanislav et al., 2012; theo et al., 2008; nikolaou et al., 2004; gauw et al., 2002; burckle et al., 2000; chao et al. 2000. 85 86 87 88 89 90 91 92 93 0 5 10 15 20 25 time on stream, (h) r o n fig. 13. effect of time on stream on ron at lhsv of 1h-1 and temperature of 553k. 4. conclusions the hydro transformation of iraqi lsrn was evaluated in a laboratory fixed bed reaction unit using 0.3wt.%pt/hmor zeolite catalyst. the following conclusions were drawn from the experimental results: 1. the prepared catalyst exhibits a high hydroisomerization activity within the studied range of operating conditions. 2. the hydroisomerization reaction is temperature dependent, and the lower temperature the greater hydrosiomerization selectivity and in turn high ron value. the optimum reaction temperature ranging between 240-280 for producing high octane number is omers. 3. the selectivity of lsrn hydroisomerization on 0.3wt.%pt/hmor catalyst could be significantly improved by increasing reaction pressure and reducing the reaction temperature. the increase of reaction pressure also causes decrease in the cracking selectivity on the catalyst. 4. the activity of 0.3wt.%pt/hmor catalyst almost independent of time on stream at 15 bar up to 20h. acknowledgement this study was supported by a grand provided by the ministry of higher education and scientific research/ 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[26] theo l.m. m., rajamani k., jasper m. v., berend s., sofia c., juan m. c. s., (2008), “shape-selective n-alkane hydroconversion at exterior zeolite surfaces”, journal of catalysis, 256, p.p. 95–107. ���� ��� �� ���� )2013( 111، �� � 4، ا ��د9 ��� ا ��ارز � ا ������ ا 11 ����� � ا �� �ل ا�� ��! ����� � ا �#ا"�� ا$%��� �&���+ ا #"* ا(و' ,pt -�� �� � ا ./)�/0 hmorا �#اج �� ر�2+ * �� ��� ���� ا �� ** ا ��� � ھ�دي ا� *** وزارة ا>;jkgh ا>e<ih وا>a@? ا>efgh / دا7cة ا>a@? وا>;:789 * **nopkcikfkq<ا prstu<ا j pkcikvwا /ex9ارزy<ا prstu<ا pkgz /ادs[\ phxi] ***p8وikfkq<ا prstu<ا jon /prstu<ا pkgz /ادs[\ phxi] *e^7و;q<wا s87a<ا :mohatiya1955@gmail.com **e^7و;q<wا s87a<ا :xp50@yahoo.comrexplore ***e^7و;q<wا s87a<ا : hoo.comalhassani_maha@ya ��5� ا ef ا>fh;ri<h ?@aاi87a;yx و 7kg@` j` 0.3wt.%pt/hmor ا>cxih ا>iefit< . sbiof ا>7hاifh;ri\ pknل ا>sbiox cxihz a8w98dا`af دراpr `@9ل e<i@<ا .p;\ie<9ة اi@<9ع ا^ kx p87a;yx cbil` ةsvل وifh;ri\ رب ا>;@9لin` a87]در[. ا kx ىsf\ ربin;<ا a87]اvت ا>@7ارة `7اوia kk\٢٠٠ s<ا ٣٥٠ º kx 7اوح` w[x٣م، و s<١٥ا kx av7او` pk|7اf 7عo\9ي، و] w[x٠.٥ s<٢.٥ا ir-١ iefit<ا s<ا kk]روsku<ا pao^ a^iz٣٠٠، و z paot pkfnv. pb7o<دة اi8d\ c~8ا>@7ارة و p]دة درi8d\ دادd8 plkly<ا pkn7اh<ا iefitg< ان ا>;@9ل �ci;t<7ت اuاظpk|7اl<ا. stb pgkgn 7ارةv p]رs\ e^i;zوwا jn7<7ات ذات اxزwا a^9q`٢٤٠ºم . p8i[<و cbil;<ا w[x دةi8d\ kk]روsku<ل اifh;ri\ 7اتxزwا k89q` pkci~;^ا ato@` .pbir w[x٢٠ [9ي و>sfة pk<ihf a^iz١٥ ا>cxih ا>sgb p;\i� sbiof ا>sوام \g]w[x . w [9ي ١٥ صفاء الدين وصالح وحيدر al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 9 , no. 1, p.p. 60-70 (2013) simulation study of mass transfer coefficient in slurry bubble column reactor using neural network safa a. al-naimi* salih a.j. salih** hayder a. mohsin*** *,*** department of chemical engineering/ university of technology ** department of chemical engineering/ university of qadisiya ***email:hachemical@yahoo.com (received 1 february 2012; accepted 7 october 2012) abstract the objective of this study was to develop neural network algorithm, (multilayer perceptron), based correlations for the prediction overall volumetric mass-transfer coefficient (kla), in slurry bubble column for gas-liquid-solid systems. the multilayer perceptron is a novel technique based on the feature generation approach using back propagation neural network. measurements of overall volumetric mass transfer coefficient were made with the air water, air glycerin and air alcohol systems as the liquid phase in bubble column of 0.15 m diameter. for operation with gas velocity in the range 0-20 cm/sec, the overall volumetric mass transfer coefficient was found to decrease with increasing solid concentration. from the experimental work 1575 data points for three systems, were collected and used to predicate kla. using spss 17 software, predicting of overall volumetric mass-transfer coefficient (kla) was carried out and an output of 0.05264 sum of square error was obtained for trained data and 0.01064 for test data. keyword: slurry bubble column reactor, mass transfer coefficient, neural network 1. introduction slurry bubble columns (sbc) are widely used in the chemical and petrochemical industries to carry out catalytic hydrogenation or oxidation reactions. sbcs are the preferred type of reactors especially for highly exothermic processes, when efficient interphase contacting is needed and when significant phase back mixing is not detrimental to the operation. these three-phase reactors are characterized with simplicity in construction, low operating cost, excellent heat and mass transfer and variable residence time. sbcs offer several advantages, such as nearly isothermal operation, good interphase contacting, large catalyst area, good productivity, operational flexibility, low pressure drop, possibility of online catalyst addition, and low pore diffusion resistance. the sbc is currently the best suited reactor for fischer-tropsch synthesis and conversion of natural gas to fuels and chemicals. this type is also considered for both direct and indirect coal liquefaction, waste water treatment as well as biotechnological applications. in sbcs, there is an intense and intimate contact between a gas-phase component, a liquid-phase component and a finely dispersed solid [1, 2]. the design and efficient exploitation of multiphase reactors require knowledge of their hydrodynamics and massand heat-transfer characteristics, e.g., pressure drop, phase holdups, massand heat-transfer coefficients, etc. rigorous treatment from first principles of multiphase flow problems remains a difficult task and has not yet attained sufficient maturity to take over the correlation-based approaches. artificial neural networks (anns), as correlation tools, hav gained wide acceptance in the field because of their inherent ability to map nonlinear relationships that tie up independent variables (either as dimensional inputs, e.g., pressure, diameter, etc., or as dimensionless inputs, e.g., reynolds, weber, and froude numbers, etc.) to the reactor characteristics to be predicted, i.e., dimensional or mailto:email:hachemical@yahoo.com safa a. al-naimi al-khwarizmi engineering journal, vol. 9, no.1, p.p. 60-70 (2013) 61 dimensionless output [3]. (ann) is the most commonly and widely used data-driven modeling technique. for modeling of the parameters for bubble column reactors, ann has been used by shaikh and aldahhan (2003) [4] for correlating the overall gas hold-up in bubble column reactors. recently, support vector regression (svr) rigorously based on statistical learning theory data has gaoined popularity for driven modeling. the focus of this study is to develop neural network algorithm (multilayer perceptron), based correlation for the prediction over all mass transfer coefficient in slurry bubble column. the input layer has nine nodes, including gas holdup, gas velocity, solution concentration, solid concentration, solution density, solution viscosity, solution surface tension, geometry ratio and diffusivity. the output layer has one node, which is the mass transfer coefficient. 2. model of ann an ann can be considered as a black box consisting of a series of complicated equations for the calculation of outputs based on a given series of input values. anns consist of collections of connected processing elements or neurons. the function of a neuron can be mathematically expressed as: a = f (wp + b) where p is the neuron input, which is multiplied by weight w, and then is summed by a bias b, a the neuron output and f is called the activation or the transfer function. neural networks are computer algorithms inspired by the way information is processed in the nervous system. an ann is a massively parallel distributed processor that has a natural propensity for storing experimental knowledge and making it available [5]. it was n reported that multilayer ann models with only one hidden layer are universal approximators. multilayer perceptron, back propagation network used in this paper is shown in fig. 1. wj,i represents the weights between the input layer vectors and hidden layer vectors, and vk,j represent the weights between the hidden layer vectors and output layer vectors. the calculated prediction error based on the following criteria: • sum of square error (sse): this method based on the following equation: sse= (experimental value predicted value)2 n 1 • relative error (re) = – 3. experimental work experiments were carried out in a column of 0.15 m in diameter and of 1.6 m in height. perforated plate sparger was used in the column. tap water, glycerin with 33 wt %, 50 wt % and 66 wt %, and alcohol solution with 0.3 wt %, 0.6 wt % and 1.5 wt % were used as the liquid phase. the physicochemical properties (table 1) were calculated from values and correlations given in perry [6]. the aspect ratio (static liquid height/diameter of column) was 2,4 and 6. pvc particles (density 1025 kg/m3, diameter 3 mm) was used as solid phase with 25 kg/m3, 50 kg/m3, 75 kg/m3, and 100 kg/m3 concentration in the column. the operation was batch with respect to liquid phase. the rate of air-flow sparged continuously was measured by a calibrated rotameter. the gas hold-up was obtained by the volume expansion method. the volumetric mass transfer coefficients were determined by the dynamic method. the material balance of the oxygen dissolved in the liquid phase is [7]: log = . ( ) . …(1) where εg and εs are gas hold up and solid hold up respectively, co and cf are initial and final concentration of oxygen respectively, ci represents the concentration of oxygen at any time in the bubble column. plotting of the left hand side of equation (1) versus (t) will give the average slop term (kla /2.303(1εgεs)), then kla can be calculated. the change in the dissolved oxygen concentration was monitored using a fast dissolved oxygen electrode. figure (2) shows the schematic diagram of the experimental apparatus. safa a. al-naimi al-khwarizmi engineering journal, vol. 9, no.1, p.p. 60-70 (2013) 62 fig. 1. multi layer perceptron, back propagation network. air compressor ٢.٢٨ oc٢٥ height of column =1.6 m d =0.15 m dissolved oxygen electrode oxygen meter rotameter fig. 2. schematic diagram of the experimental apparatus. safa a. al-naimi al-khwarizmi engineering journal, vol. 9, no.1, p.p. 60-70 (2013) 63 4. results and discussion from the ranges of the data obtained in experimental work (table 1), the developed models can be used to predict the mass transfer parameters in slurry bubble column reactor operating under typical conditions (1575 data were used). in this study, the model was used to predict the volumetric mass transfer coefficient, in slurry bubble columns sbc. from spss 17®, 78 try and error attempts were done by the option multilayer perceptron (mlp) and through using automatic architecture selection option as shown in figure 3 a & b. figure 4 shows the data partition’s used in this prediction (70% of data was trained and 30% for testing). table 1, the range of data obtained in the experimental work. variables gas holdup gas velocity solution concentration maximum 0.545455 0.20608 1 minimum 0.00217 0.02167 0.003 units m/s w/w variables density viscosity surface tension maximum 1173 0.0225 0.072 minimum 991 0.0009 0.0009 units kg/m3 pa.s n/m variables aspect ratio diffusivity*10-9 maximum 6 20.807 minimum 2 0.048 units m2/s variables solid concentration maximum 100 minimum 0 units kg/m3 the back propagation neural network (bpnn) selected for predicting kla has the following topology: (9, 2, 1).the learning rate for the kla bpnn was 0.25 and 1500 iterations were used during the training and learning process. the values of sse, and re of 5.264 and 1.064, respectively (table 2), were obtained with this bpnn. fig. 3-a. spss statistics data editor. fig. 3-b. multi layer prediction. safa a. al-naimi al-khwarizmi engineering journal, vol. 9, no.1, p.p. 60-70 (2013) 64 table 2, model summary training sum of squares error (sse) 5.264 relative error (re) 0.010 stopping rule used 1 consecutive step(s) with no decrease in error training time 0:00:01.520 testing sum of squares error 1.064 relative error 0.027 figure 5 shows the comparison between experimental and predicted kla values using the bpnn. figure 6 shows the iterations with errors counted for each iterate. fig. 5. the comparison between experimental and predicted kla using bpnn. fig. 6. the iterations with errors counted for each iterate. 4.1. effect of gas velocity on mass transfer coefficient figures 7 to 10 show the relation between gas velocity and mass transfer coefficient for experimental and predicted values. as can be seen in these figures kla values increase with gas fig. 4. the partition data. 0 0.05 0.1 0.15 0.2 0.25 0 0.05 0.1 0.15 0.2 0.25 ex pe rm in ta l predicted 0 10 20 30 40 50 60 70 80 90 attempt no. 0 10 20 30 40 50 60 e rro r % sse re safa a. al-naimi al-khwarizmi engineering journal, vol. 9, no.1, p.p. 60-70 (2013) 65 0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18 0.20 0.22 gas velocity (m/s) 0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 m as s tr an sf er c oe ffi c. (m 2 /s ) exp pred solid conc. 75 kg/m3 solution conc. 1.5 % system alcohol l/d = 4 s 0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18 0.20 0.22 gas velocity (m/s) 0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 m as s tr an sf er c ef fic . (m 2 /s ) exp pred solid conc. 50 kg/m3 solution conc. 0.3 % system alcohol l/d = 4 s 0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18 0.20 0.22 gas veloci ty (m/s) 0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 m as s tr an sf er c oe ffi c (m 2 /s ) exp pred solid conc. 25 kg/m3 solution conc. 0.6 % system alcohol l/d = 4 velocity. this increase of kla can be observed for all solid concentrations and liquid systems. these results pointed out that in the churn-turbulent regimes, as the superficial gas velocity increases the overall mass transfer coefficient increases due to the large bubble holdup increase. in bubbly flow regime, number of bubbles increases with increasing superficial gas velocity leading to increase the gas-liquid interfacial area. fig. 7. the relation between gas velocity and volumetric mass transfer coefficient for alcohol system, 75 kg/m3 solid concentration. fig. 8. the relation between gas velocity and volumetric mass transfer coefficient for alcohol system, 50 kg/m3 solid concentration. these results are in agreement with krishna and van baten (2003) [8] and verma and rai (2003) [9]. these figures compare the predictions of the proposed simulation with the experimental data. it can be seen that the proposed ann correlation agrees reasonably with the experimental data. fig. 9. the relation between gas velocity and volumetric mass transfer coefficient for alcohol system, 25 kg/m3 solid concentration. fig. 10. the relation between gas velocity and volumetric mass transfer coefficient for glycerin system, 100 kg/m3 solid concentration. m as s t ra ns fe r c oe ff ic ie nt (s -1 ) m as s t ra ns fe r c oe ff ic ie nt (s -1 ) m as s t ra ns fe r c oe ff ic ie nt (s -1 ) m as s t ra ns fe r c oe ff ic ie nt (s -1 ) 0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18 0.20 0.22 gas velocity (m/s) -0.005 0.000 0.005 0.010 0.015 0.020 0.025 0.030 0.035 m as s tr an sf er c oe ffi . (m 2 /s ) exp pred solid conc. 100 kg/m3 solution conc. 0.5 % system: glyceren l/d = 4 s m as s t ra ns fe r c oe ffi ci en t ( s-1 ) safa a. al-naimi al-khwarizmi engineering journal, vol. 9, no.1, p.p. 60-70 (2013) 66 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 gas holdup 0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 m as s tr an sf er c oe ffi c (m 2 /s ) mass exp mass pred solid conc. 75 kg/m3 soulation conc 0.3-1.5 % system : alcohol l/d = 4 s 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 gas holdup 0.00 0.02 0.04 0.06 0.08 0.10 0.12 m as s tr an sf er c oe ffi c (m 2 /s ) mass exp mass pred solid conc. 0 kg/m3 soulation conc 0 % system : water l/d = 4 s 4.2. effect of gas holdup figures 11 to 13 show a comparison between the predictions obtained using the ann correlation and experimental data for air-water and air-alcohol systems at different solid concentrations and gas velocity. the trend shown by the ann correlation is in a good agreement with experimental work. these figures show that, the volumetric mass transfer coefficient kla increases with increasing gas holdup. these results pointed out that higher gas holdup led to increase gas-liquid interfacial areas leading to a higher mass transfer coefficient kla. fig. 11. the comparison between ann correlation and experimental data for air-alcohol system at 75 kg/m3 solid concentration. fig. 12. the comparison between ann correlation and experimental data for air-alcohol system at 50 kg/m3 solid concentration. fig. 13. the comparison between ann correlation and experimental data for air-water system. 4.3. effect of solid concentration the experiments performed with addition of solid showed that, the volumetric mass transfer coefficient kla decreases with increasing solid concentration as shown in fig. 14, 15 and 16, whereas, the gas-liquid interfacial area decreases with increasing solid concentration. the decrease of mass transfer coefficient with increasing solid concentration is attributed to decrease of small bubble and increase large bubble size due to the bubble coalescence tendencies and they limited the mass transfer coefficient. these results are in agreement with vandu and krishna (2004) [10] and koide et al. (1984) [7]. figures 15 and 16 shows a good agreement of ann predictions with the experimental data. gas holdup [-] m as s t ra ns fe r c oe ffi ci en t ( s-1 ) gas holdup [-] m as s t ra ns fe r c oe ffi ci en t ( s-1 ) 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 gas holudup 0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 m as s tr an sf er c oe ffi c (m 2 /s ) mass exp 3 mass pred 3 solid conc. 50 kg/m3 soulation conc 0.3-1.5 % system : alcohol l/d = 4 s gas holdup [-] m as s t ra ns fe r c oe ffi ci en t ( s-1 ) safa a. al-naimi al-khwarizmi engineering journal, vol. 9, no.1, p.p. 60-70 (2013) 67 fig. 14. effect of solid concentration on mass transfer coefficient for 0.3 % alcohol system and l/d=4. 4.4. effect of the type of liquid phase to check the effect of liquid physical properties, ann predictions were carried out at different liquid viscosities and liquid surface tension. the experiments performed with viscous media (glycerin systems) showed that the volumetric mass transfer coefficient decreases with increasing liquid viscosity as shown in fig. 17. it was pointed out that, higher viscosity led to increase of the volume fraction of large bubbles, leading to much lower gas-liquid interfacial areas while kla values increased in the presence of alcohol as shown in fig. 18 and 19. the increase of kla with the presence of alcohol is attributed to creation of small bubbles and reduced bubble coalescence due to the surfactant. as a result, the presence of small bubbles should be preferred and the presence of large bubbles should be avoided for effective mass transfer rates, these results are in agreement with ozturk et al. (1987) [11] and behkish et al. (2002) [12]. in these figures, the predictions of proposed simulation fit the experimental data reasonably well. m as s t ra ns fe r c oe ffi ci en t ( s-1 ) gas velocity (m/sec) 0.00 0.05 0.10 0.15 0.20 0 .25 0 .30 0 .35 0 .40 0 .45 0 .50 gas ho ludup 0 .00 0 .02 0 .04 0 .06 0 .08 0 .10 0 .12 0 .14 0 .16 m as s tr an sf er c oe ffi c. (m 2 /s ) m ass exp m ass p red so lid conc. 100 kg /m 3 soulation conc 0.3 -1 .5 % system : a lcoho l l/d = 4 s m as s t ra ns fe r c oe ff ic ie nt (s -1 ) gas holdup [-] solution conc. = 0.3 1.5 % fig. 15. the comparison between ann correlation and experimental data for airalcohol system at 100 kg/m3 solid concentration. 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 gas holudup 0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 m as s tr an sf er c oe ffi c (m 2 /s ) mass exp mass pred sol id conc. 25 kg/m3 soulation conc 0.3-1.5 % system : alcohol l/d = 4 s m as s t ra ns fe r c oe ff ic ie nt (s -1 ) solution conc. = 0.3 1.5 % gas holdup [-] fig. 16. the comparison between ann correlation and experimental data for airalcohol system at 25 kg/m3 solid concentration. safa a. al-naimi al-khwarizmi engineering journal, vol. 9, no.1, p.p. 60-70 (2013) 68 0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18 0.20 0.22 gas veloci ty (m/s) 0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 m as s tr an sf er c oe ffi . (m 2 /s ) exp pred solid conc. 100 kg/m3 solution conc. 0.6 % system alcohol l/d = 4 s 0.00 0.02 0.04 0 .06 0 .08 0 .10 0 .12 0.14 0.16 0.18 0.20 0 .22 gas veloci ty (m /s) 0.00 0.02 0.04 0.06 0.08 0.10 m as s tr an sf er c oe ffi c. (m 2 /s ) exp p red so lid conc. 100 kg /m 3 so lu tion conc. 0 % system wate r l/d = 4 s gas holdup 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 m as s tr an sf er c oe ffi c (m 2 /s ) 0.00 0.01 0.02 0.03 0.04 0.05 0.06 mass exp (33% sol. conc.) mass pred (33% sol. conc.) mass exp (50% sol. conc.) mass pred (50% sol. conc.) mass exp (66% sol. conc.) mass pred (66% sol. conc.) fig. 17. effect of liquid viscosity on volumetric mass transfer coefficient. fig. 18. the relation between gas velocity and volumetric mass transfer coefficient for alcohol system, 100 kg/m3 solid concentration. fig. 19. the relation between gas velocity and volumetric mass transfer coefficient for water system, 100 kg/m3 solid concentration. 5. conclusion 1. it can be concluded that the volumetric mass transfer coefficient, kla increases with increasing gas velocity and gas holdup whereas decreases with increasing solid concentration and liquid viscosity. it is also concluded that the presence of surfactants increase kla, due to the presence small bubbles. 2. the ann model for prediction of mass transfer coefficient is developed successfully in this work. in this model, the number of nodes in the input layer, hidden layer and output layer are 9, 2 and 1 respectively. the nodes in the input layer are including gas holdup, gas velocity, solution concentration, solid concentration solution density, solution viscosity, solution surface tension, geometry ratio and diffusivity. the node in output layer is mass transfer coefficient. 3. the sum of square error and relative error are used to assess the performance of ann model. this ann model demonstrated a good statistical performance with the sum of square error and relative error of (5.264% and 1.064% respectively) which are very low values relative to the range of the experiments. m as s t ra ns fe r c oe ff ic ie nt (s -1 ) gas holdup [-] m as s t ra ns fe r c oe ff ic ie nt (s -1 ) m as s t ra ns fe r c oe ff ic ie nt (s -1 ) safa a. al-naimi al-khwarizmi engineering journal, vol. 9, no.1, p.p. 60-70 (2013) 69 6. references [1] nedeltchev s. and schumpe a., "theoretical prediction of mass transfer coefficient in slurry bubble column in the homogeneous regime", chem. biochem. eng. q. 21 (4) 327–334 (2007). [2] gupta p. , merchant s. , bhat u. and gandhi b., "development of correlations for overall gas hold-up, volumetric mass transfer coefficient, and effective interfacial area in bubble column reactors using hybrid genetic algorithm-support vector regression technique: viscous newtonian and non-newtonian liquids", ind. eng. chem. res., 48, 9631–9654 (2009). [3] tarca a. , grandjean a. and larachi f. "artificial neural network meta models to enhance the prediction and consistency of multiphase reactor correlations", ind. eng. chem. res., 42, 1707-1712 (2003). [4] ashfaq s. and muthanna al-dahhan, "development of an neural correlation for prediction of overall gas holdup in bubble column reactors", che. eng. and processing 42 599-610 (2003). [5] ripley b.d., "pattern recognition and neural networks", cambridge university press, cambridge, (1996). [6] perry, "chemical engineers' handbook", 6th edition, new york: mcgraw-hill, (1984). [7] koide k. , takazawa a., komura m. and matsunga h. "gas holdup and volumetric liquid phase mass transfer coefficient in solid suspended bubble column", j chem. eng. jpn 17, 459-466 (1984). [8] krishna r, van baten jm, "mass transfer in bubble columns", catal today vol. 79-80, 67-75 (2003). [9] verma ak, rai s, "studies on surface to bulk ionic mass transfer in bubble column", chem. eng. j., vol. 94, 6772(2003). [10] vandu co, krishna r, "volumetric mass transfer coefficients in slurry bubble columns operating in churn – turbulent flow regime", chem. eng. process vol. 43,987-995,(2004). [11] ozturk ss., schumpe a., and deckwer wd. "organic liquid in a bubble column: holdups and mass transfer coefficient" aiche j, 33, 1473-1480 (1987). [12] behkish a, men z, inga rj., moris bi.,"mass transfer characteristics in a large scale slurry bubble column reactor with organic liquid mixtures", chem. eng. sci. vol. 57, 3307-3324(2002). )2013(60-70 ، صفحة 1، العدد9مجلة الخوارزمي الھندسیة المجلد صفاء الدین عبد اهللا النعیمي 70 دراسة محاكاة معامل انتقال الكتلة في العمود الفقاعي ثالثي األطوار باستخدام الشبكات العصبیة الصناعیة ***حیدر عبد الكریم محسن **صالح عبد الجبار صالح *صفاء الدین عبد اهللا النعیمي التكنولوجیةالجامعة /قسم الھندسة الكیمیاویة ***،* جامعة القادسیة /قسم الھندسة الكیمیاویة** hachemical@yahoo.com *** :االلكتروني البرید الخالصة في مفاعل ) kla(و اعتماد عالقات معامل انتقال الكتلة الحجمي ) متعّدد الطبقة perceptron(ھدف ھذه الدراسة كان تطویر خوارزمیة الشبكة عصبیِة، متعّدد الطبقة ھو تقنیة مبتكرة و معتمدة على میزة نظریة الجیِل باستخدام شبكة التولیِد ) (perceptron). صلب-غاز-سائل(العمود الفقاعي ثالثي االطوار ھواء (و ) ھواء وغلیسرین(, ) ھواء وماء(م وباستخدام ثالثة انظمة وھي ٠.١٥كتلة في عمود فقاعي ذي قطر تم قیاس معامل انتقال ال. العصبیة العكسیة تم . ثانیة و وجد بأن معامل انتقال الكتلة قد تناقص بزیادة تركیز الصلب في العمود/سم ٢٠الى ٠تم تشغیل العمود الفقاعي بسرع غاز تراوحت من ). وكحول تم و (spss 17)باستخدام برنامج klaطة من التجارب العملیة لألنظمة الثالثة واستعملت ھذه النتائج العملیة للتكھن بقیم نق ١٥٧٥الحصول على .لبیانات اإلختبار) ٠.٠١٠٦٤(للبیابات التدریبیة و) ٠.٠٥٢٦٤(المتوقع من البرنامج و بمربع خطأ مقداره ) kla(الحصول على معامل انتقال الكتلة الحجمي mailto:hachemical@yahoo.com علياء خضير مجيد38-30 al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 7, no. 3, pp 30 38 (2011) effect of solid loading on carbon dioxide absorption in bubble column alyaa khadhier mageed department of chemical engineering/ university of technology email: aliaamce_1980@yahoo.com (received 3 may 2011; accepted 30 jun 2011) abstract in the present work experiments were conducted to study the effect of solid loading (1,5 and 9 vol.%) on the enhancement of carbon dioxide absorption in bubble column at various volumetric gas flow rate (0.75, 1 and 1.5 m3/h) and absorbent concentration (caustic soda)( 0.1,0.5 and 1 m ). activated carbon and alumina oxide (al2o3) are used as solid particles. the danckwerts method was used to calculate interfacial area and individual mass transfer coefficients during absorption of carbon dioxide in a bubble column. the results show that the absorption rate was increased with increasing volumetric gas flow rate, caustic soda concentration and solid loading. mass transfer coefficient and interfacial area were increased with increasing volumetric gas flow rate, and solid loading. keywords: carbon dioxide absorption, bubble column, danckwerts method, mass transfer coefficients and interfacial area. 1. introduction slurry bubble columns are intensively used as a multiphase contactors in the chemical, biochemical and petrochemical industries where heterogeneous gas-liquid or gas-solid reactions take place, particularly, in which the liquid phase controls mass transfer process due to the relation with solubility of gases[1, 2]. important applications of three phase bubble column are in hydrogenation, oxidation, and waste water treatment and in biochemical applications [2]. the rate of acid gas absorption such as carbon dioxide absorption in a gas-liquid or gas-liquidsolid contactor may be enhanced considerably by the presence of particles in the liquid –phase. to be effective, the particles have to be considerably smaller than the gas-liquid film thickness and need to have a high affinity for the component to be transferred. enhancement of the gas absorption rates due to the presence of small particles is explained by the so-called grazing or shuttle mechanism [3-6]. sharma and mashelkar (1968) [7] were the first to report an increase in the mass transfer in a bubble column by small particles. similar effects were found later by wimmers and fortuin (1988) [8], beennackers and van swaaij (1993) [6] and marius et al (2007) [9]. lindner et al (1988) [10] and kluytmans et al (2003) [11] found that in non-coalescing liquids, e.g., concentrated salt solutions, fine activated carbon particles may hinder bubble coalescence and significantly increase the specific interfacial area. vandu and krishnal (2004) [12] observed that addition of solids and high solid concentrations caused reduced values of mass transfer coefficients due to increased large bubble size. sumin et al (2007) [13], studied the absorption of carbon dioxide in carbonate solution (k2co3) in the presence of activated carbon particles and found that the absorption rate enhanced significantly, and the maximum enhancement factor was 3.7. the present work aimed to study the absorption rate of carbon dioxide in caustic soda (naoh) solution 0.1, 0.5 and 1m at different volumetric gas flow rate 0.75, 1 and 1.5 m3/h and carbon dioxide concentration of 10% by volume mailto:aliaamce_1980@yahoo.com alyaa khadhier mageed al-khwarizmi engineering journal, vol. 7, no. 3, pp 30 38 (2011) 31 with and without solid particles (activated carbon and alumina oxide (al2o3) (1, 5 and 9 vol.%), keeping other variables constant as temperature of (20±2)oc, and atmospheric pressure. 2. experimental work experiments of absorption of carbon dioxide from gaseous mixture (10% carbon dioxide air) has been carried out by using aqueous solution of (0.1, 0.5 and 1m) naoh. this has been performed in a conventional slurry glass cylindrical bubble column of 7.5 cm inside diameter, 100 cm height over a wide range of gas flow rate of 0.75, 1 and 1.5 m3/h (as velocity 0.0117-0.0235 m/sec), solid loading (1, 5 and 9vol.%) and different types of solid particles (activated carbon, alumina oxide) to study the effect of these parameters on the fractional conversion, absorption rate and mass transfer coefficient of carbon dioxide. schematic diagram of experimental set up is shown in figure (1).table (1) shows the characteristics properties of activated carbon, alumina oxide. perforated plate sparger was used as a gas distributor 104 hole of 1mm diameter and placed between the column and distributor chamber which has a drain at the bottom and gas inlet at the side. fig.1. experimental set up for carbon dioxide absorption. pressurized co2 source one way val ve 2 one way valve 1 pump compressor rotameter 1 rotameter 2 tank gas outlet liquid outline thermocouple sampling liquid inlet bubble column gas inlet co2 cylinder alyaa khadhier mageed al-khwarizmi engineering journal, vol. 7, no. 3, pp 30 38 (2011) 32 table 1, the characteristics properties of activated carbon, alumina oxide. activated carbon (a.c) surface area (m2/g) 1122 bulk density (g/m3) 0.44 porosity ( ) 0.46 particle diameter (m) 1.1*10-3 min. fluidizing velocity (m/s) 0.000329 particle terminal velocity (m/s) 0.00309 alumina oxide (al2o3) surface area (m2/g) 300 bulk density (g/m3) 0.56 porosity ( ) 0.51 particle diameter (m) 1.5*10-3 min. fluidizing velocity (m/s) 0.00537 particle terminal velocity (m/s) 0.0521 3. procedure of experiment in all experiments the volume of liquid has been set constant and equal to 1.5 liter, 30 cm height above the sparger. the gas flow of carbon dioxide and air were measured by two calibrated rotameters separately, then entered the bottom of the bubble column. the samples were taken from the side of the bubble column every 3 min. . the temperature was measured periodically by a thermocouple until the end of the experiment. all experiments were performed at constant temperature of (20±2)oc and atmospheric pressure. 3.1. chemical reactions when carbon dioxide is absorbed into aqueous sodium hydroxide solutions, the following two reactions should be considered [14, 15]: co2 + oh= hco3 …(1) hco3 + oh= co3 2 +h2o …(2) at 30oc and at infinite dilution reaction (1) is practically considered irreversible and second order, i.e. first order with respect to both carbon dioxide and ohions. reaction (2) is a proton transfer reaction and has a very much higher rate constant than reaction (1), thus this reaction can be regarded as an instantaneous reversible reaction[14, 15]. in strong hydroxide solutions, the equilibrium concentration of hco3 ions can be neglected and the overall reaction is: co2 + 2oh= co3 2 + h2o …(3) 3.2. physcio chemical properties 1. diffusivity (dco2-naoh) of carbon dioxide in aqueous caustic soda solution was estimated as follows[16 ]: da = 1.833*10-6t -4.717*10 -4 – 1.042*10-5n …( 4 ) 2. reaction rate constant (k2) was estimated as follows[9, 17]: 2 2 016.0221.02895985.11log cc ii t k −+−= …(5) where ic is the ionic strength and can be estimated as follows: iic czi 2 2 1 ∑= …(6a) [ ]3*2*1 2 1 coohi c += …(6b) let ( ) ( )231 bcoandboh == then m=b1+2b2 my =b2 mi c 2 1 =∴ …(6c) 3. solubility of carbon dioxide in the liquid phase was calculated using the henry's law. henry's law constant for co2-na2co3 system was determined as follows[ 10]: ∑−= ico hi h hlog …(7) where gi hhhh ++= +− h_ for oh=0.061 liter/g ion h+ for na+ =0.094 liter/g ion hg for co2 =-0.017 liter/g ion where ho is henry's law constant for co2 in water and can be obtained as follows[13]: 2520 10*8857.710*9044.51229.9log tth −− +−= …(8) 4. [ ] [ ] = inputnaoh reactednaohnaconversiocausticsod % …(9) alyaa khadhier mageed al-khwarizmi engineering journal, vol. 7, no. 3, pp 30 38 (2011) 33 3.3. interfacial area a and individual mass transfer coefficient kl danckwerts method was used to calculate the interfacial area (a) and the individual mass transfer coefficient (kl) as follows [18, 19]: 2 2 * 2 l bulk baoc kckdacn += …( 10) [ ]2 2 2 2 * 2 akckda c n l bulk ba oc +=         …( 11) interfacial area a and individual mass transfer coefficient kl are obtained by plotting 2 * 2         occ n vs. bulk ba ckd 2 , the relation is straight line of slope a2 and intercept [ ]2 akl . figure (2) shows danckwerts plot for estimated interfacial area (a) and mass transfer coefficient (kla). this method is used when the concentration of absorbent is not constant with time. fig.2. danckwerts plot: a) free solid concentration; b) 1% vol. al2o3 solid concentration at different volumetric gas flow rate. fig.3. caustic soda concentration vs. time at 0.75 m3/h volumetric gas flow rate. alyaa khadhier mageed al-khwarizmi engineering journal, vol. 7, no. 3, pp 30 38 (2011) 34 this implies that a part of the chemical reaction between carbon dioxide and hydroxyl ions is carried out at interface and the other part in the bulk of the liquid. therefore; the surface renewal theory developed by danckwerts is satisfied for estimating interfacial area a and mass transfer coefficient kla[19 ]. figure (3) shows the caustic soda concentration during carbon dioxide absorption at a given condition. it can be seen that the caustic soda decreases with time. 4. results and discussion 4.1. influence of superficial gas velocity figures (4 to 6) show the effect of volumetric gas flow rate on absorption rate, mass transfer coefficient and interfacial area. it can be seen that at a given solid loading the absorption rate increased with increasing volumetric gas flow rate. this is attributed to the fact that the rate of breakup of bubble increased. in addition, higher superficial gas velocity gives smaller bubbles. the smaller bubble of lower rising velocity leads to form large residence time and consequently higher gas – liquid interfacial, mass transfer coefficient and absorption rate .these results are in agreement with previous work [20, 21]. fig.4. absorption rate vs. total volumetric gas flow rate (co2+air): a) a.c solid loading , b) al2o3 solid loading. fig.5. interfacial area vs. total volumetric gas flow rate (co2+air). alyaa khadhier mageed al-khwarizmi engineering journal, vol. 7, no. 3, pp 30 38 (2011) 35 fig.6. mass transfer coefficients vs. total volumetric gas flow rate (co2+air). fig.7. absorption rate vs. total volumetric gas flow rate (co2+air) as a function of absorbent concentration and solid loading: a) a.c solid loading; b) al2o3 solid loading. alyaa khadhier mageed al-khwarizmi engineering journal, vol. 7, no. 3, pp 30 38 (2011) 36 4.2. influence of absorbent concentration figure (7) shows the effect of absorbent concentration on absorption rate at a given volumetric gas flow rate and solid loading. the results show that the absorption rate increases with increasing absorbent concentration. increasing of absorbent concentration will cause the zone of reaction approach the gas-liquid interface rapidly which leads to increase the driving force (∆c) and decreases the thickness of the liquid film through the solute due to increase oh concentration in solution that reacts with carbon dioxide which leads to increase the reaction controlling step (equation 2). these results are in agreement with previous work [22, 23, 24]. 4.3. influence of solid loading figures (4 to 7) show the effect of solid loading on absorption rate, mass transfer coefficient and interfacial area. it can be seen that the absorption rate, mass transfer coefficient and interfacial area increase with increasing solid loading. enhancement of the gas absorption rates due to the presence of small particles is explained by the so-called grazing or shuttle mechanism. it is assumed that the particles travel between the stagnant liquid mass transfer layer and the bulk of the liquid. near the interface, the adsorptive particles are loaded with solute and the solute concentration in the liquid mass transfer layer decreases. the concentration gradient of the solute in the mass transfer layer increases leading to enhance gas absorption. after a certain time in the liquid side mass transfer layer, the particles returns to the bulk of the liquid where the gasphase component is desorbed and the particle regenerated [3-6, 13, 25]. due to the hydrophobic properties of active carbon, the concentration of particles in the mass transfer zone is much higher than in the bulk of the suspension, leading to higher absorption rates and mass transfer coefficients [25]. also, the surface area of activated carbon was higher than the alumina. this leads to that the absorption rate, mass transfer coefficient and interfacial area with activated carbon particle is higher than that when alumina particle was loaded. 5. conclusions the following points are concluded from the present work: § the absorption rate increased with increasing volumetric gas flow rate and absorbent concentration within the conditions used. § the absorption rate, mass transfer coefficient and interfacial area increase with increasing solid loading according to grazing or shuttle mechanism. § danckwerts method was used to calculate interfacial area (a) and individual mass transfer coefficient (kl). nomenclature symbol unit definition a m2/m3 interfacial area cb kmol/m3 concentration of liquid reactant (b) in the bulk * 2occ kmol/m3 concentration of carbon dioxide at equilibrium ci kmol/m3 concentration of ions ad m2/s diffusivity of carbon dioxide in caustic soda solution h atm.m3/kmol henry's constant ho atm.m3/kmol henry's constant in pure water hi l/g ion parameters of equation 7 of h+, hand hg respectively, hi = h+ h+ + hg h+ l/g ion parameter of cation hl/g ion parameter of anion hg l/g ion parameter of gas ic m3/ kmol ionic strength kl.a 1/ s mass transfer coefficient lk m/s liquid side mass transfer coefficient k2 m3/kmol.s reaction rate constant n kmol/m3.min. absorption rate m kmol/m3 molarity t k temperature y ( ) fractional conversion zi ( ) valance of ion 6. references [1] lye, g.j., stuckey, d.c., "extraction of erythromycin-a using colloidal liquid aphrons: part ii. mass transfer kinetics", chem. eng. sci., 56 (2001) 97-108. [2] nigar, k., faher, b., kutlu, o.u., "bubble column reactors", process biochemistry, 40 (2005) 2263-2283. alyaa khadhier mageed al-khwarizmi engineering journal, vol. 7, no. 3, pp 30 38 (2011) 37 [3] chandrasckaran, k., sharma, m.m., "absorption of oxygen in aqueous solutions of sodium sulfide in the presence of activated carbon as catalyst", chem. eng., sci., 32 (1977) 669. [4] quicker, g., alper, e., deekwar, w.d., "effect of fine activated carbon particles on the rate of carbon dioxide absorption", a.i.ch.e. j., 33 (1987) 871. [5] vinke, h., hamersma, p.j. fortuin, j.m.h., "enhancement of the gas-absorption rate in agitated slurry reactors by gas-absorbing particles adhering to gas bubbles", chem. eng. sci., 48 (1993) 2197. [6] beenackers, a.a.c.m., van swaaij, w.p.m., "mass transfer in gas-liquid slurry reactors", chem. eng. sci., 48 (18) (1993) 3109. [7] sharma, m.m., mashelkar, r.a., "absorption with reaction in bubble columns", institute of chemical engineers symposium series, 28 (1968) 10-21. [8] wimmers, o.j., fortuin, j.m.h., "the use of adhesion of catalyst particles to gas bubble to achieve enhancement of gas absorption in slurry reactor part", chem. eng. sci., 43 (1988) 119-313. [9] marius, r., anita, m., aydin, k., adrian, s., "surfactant adsorption on to activated carbon and its effect on absorption with chemical reaction", chem. eng. sci., 62 (2007) 73367343. [10] lindner, d., werner, m., schumpe, a., "hydrogen transfer in slurries of carbon supported catalysts (hpo process). a.i.ch.e.j., 34 (1988) (10) 1691-1697. [11] kluytmans, j., van wachem, g., kuster, b., schouten, j., "mass transfer in sparged and stirred reactors: influence of carbon particles and electrolyte", chem. eng. sci., 58 (2003) 4719-4728. [12] vandu, c.o., krishna, r., "volumetric mass transfer coefficients in slurry bubble columns operating in churn-turbulent flow regime", chem. eng. process, 43 (2004) 987-95. [13] sumin, l.u., youguang, m.a., chunying, z.h.u., shuhua, s.h.e.n., "the enhancement of carbon dioxide chemical absorption by potassium carbonate aqueous solution in the presence of activated carbon particles", chin. chem. eng. j., 15(2007) (15)842-846. [14] hikita, h., asia, s., takatsuka, t., "absorption of carbon dioxide into aqueous sodium hydroxide and sodium carbonatebicarbonate solutions" chem. eng. j., 11 (1976) 131. [15] danckwerts, p.v., "gas-liquid reactions", mc-graw hill, new york, 1970. [16] wales, c.e., "physical and chemical absorption in two-phase annular and dispersed horizontal flow", aiche.j., 12,6 (1966) 1166. [17] astarita, g., savage, d.w. and bisio ,a.," gas treating with chemical solvent " , wiley, new york, 1983. [18] zhao wei-rong, shi hui-xiang, and wang da-hui, "modling of mass transfer characteristics of bubble column reactor with surfactant present", journal of zhejiang university science ,5,6(2004) 714-720. [19] navaza, j.m., gomez-diaz, d., and dolores le, r...,"removal process of co2 using mdea aqueous solutions in a bubble column reactor", chem.eng.sci. , 146, (2009), 184-188. [20] mouza, a.a., dalakoglou, g.k, paras, s.v., “effect of liquid properties on the performance of bubble column reactors with fine pore spargers”, chem. eng. sci., 60 (2005) 1465 – 1475. [21] maalej, s., benadda, b., and otterbein, m.,"interfacial area and volumetric mass transfer coefficient in a bubble column reactor at elevated pressure" , chem. eng. sci., 58 (2003) 2365 – 2376. [22] yih, s.m., and sun, c.c., “simultaneous absorption of hydrogen sulphide and carbon dioxide into potassium carbonate solution with or without amine promoters" chem.eng.j., 34(1987)65. [23] maceiras, r., alvarez, e., and cancela, m.a., "effect of temperature on carbon dioxide absorption in monoethanolamine solutions", chem. eng. j., 138 (2008) 295300. [24] lin, s. h., tung, k.l., chen, w.j., and chang, h.w., "absorption of carbon dioxide by mixed piperazine–alkanolamine absorbent in a plasma-modified polypropylene hollow fiber contactor", j.membr.sci., 333 (2009) 30-37. [25] dagaonkar, m.v., heeres, h.j., beenackers , a.a.c.m., and pangarkar , v.g., " the application of fine tio2 particles for enhanced gas absorption" , chem. eng. j., 92 (2003) 151–159. )2011( 30 38، صفحة 3، العدد 7مجلة الخوارزمي الھندسیة المجلد علیاء خضیر مجید 38 غازدراسة تأثیر تحمیل مادة الصلب على عملیة امتصاص ثنائي اوكسید الكربون في العمود الفقاعي علیاء خضیر مجید التكنولوجیة ةالجامع/ قسم الھندسة الكیمیاویة الخالصة معدل كربون في العمود الفقاعي فياوكسیدالعلى عملیة امتصاص غاز ثنائي )نسبة حجمیة%٩, ٥, ١(ھذا البحث تضمن دراسة تأثیر تحمیل الصلب المنشط الكربون تم استعمال ).٣م\كیلومول ١, ٠و٥, ٠و١)(اوكسید الصودیوم(وتركیز المادة الماصة ) ساعة\ ٣م) ١و٥, ١ ,٠و٧٥((التدفق الحجمي للغاز امل انتقال الكتلة اثناء عملیة امتصاص غاز ثنائي اوكسیدالكربون في طریقة دانكویرتز استعملت لحساب المساحة البینیة ومع. كمواد صلبة واوكسید االلمنیوم . العمود الفقاعي كما تبین .حمیل الصلبومقدار ت) اوكسید الصودیوم(تركیز المادة الماصة,اظھرت النتائج ان معدل االمتصاص یزداد بزیادة معدل التدفق الحجمي للغاز . الصلب الحجمي للغاز ومقدار تحمیل ان معامل انتقال الكتلة والمساحة البینیة یزدادان بزیادة معدل التدفق al-khwarizmi engineering!!! journal al-khwarizmi engineering journal, vol. 7, no. 2, pp 22 35 (2011) comparative study of the mechanical properties of (fs) and mig welded joint in (aa7020-t6) aluminum alloy moneer hammed tolephih * kadhim m. mashloosh ** zainab waheed *** the technical college/ baghdad * email: monerht@yahoo.com ** email: kadm52@yahoo.com *** email: zainab.wa83@yahoo.com (received 24 october 2010; accepted 15 may 2011) abstract a comprehensive practical study of typical mechanical properties of welded aluminum alloy aa7020-t6 (al-mgzn), adopting friction stir welding (fsw) technique and conventional metal inert gas (mig) technique, is well achieved in this work for real comparison purposes. the essences of present output findings were concentrated upon the fsw samples in respect to that mig ones which can be summarized in the increase of the ultimate tensile strength for fsw was 340 mpa while it was 232 mpa for mig welding, where it was for base metal 400 mpa. the minimum microhardness value for fsw was recorded at haz and it was 133 hv0.05 while it was 70 hv0.05 for mig weld at the welding metal. the fsw produce 2470 n higher than mig welding in the bending test and a decrease in the localized grain size for fsw in the stirred zone 12 µm and it was 37 µm for mig while it was 32 µm for the base metal. keyword: fsw friction, stir welding, solid state, mig metal inert gas, fusion, mechanical properties. 1. introduction friction stir welding (fsw) is a solid state welding technique used for joining successfully aluminum alloys. this technique is being applied to the aerospace, automotive, and shipbuilding industries, and it is attracting an increasing amount of research interest [1]. a friction stir butt weld is produced by plunging a rotating tool into the facing surfaces of two plates. the tool consists of a shoulder and a profiled pin emerging from it. as the rotating pin moves along the weld line, the material is heated up by the friction generated by the shoulder and stirred by the rotating pin in a process similar to an extrusion. since the temperatures are well below the melting point, problems associated with the liquid/solid phase transformation are avoided [2]. in 1940 experiments began in the usa, in attempt to weld magnesium with aluminum base metals, with the shielding of the arc by inert gases. some years later the mig (metal inert gas) welding process was also developed using a continuously fed metal wire as the electrode [3]. gas metal arc welding is a process that melts and joins metals by heating them with an arc established between a continuously fed filler wire electrode and the metals. shielding of the arc and the molten weld pool is often obtained using inert gases such as argon and helium. this is the most widely used arc welding process for aluminum alloy [4]. fsw has several advantages over the commonly used fusion welding techniques: 1the welding procedure is relatively simple with no consumables or filler metal. 2joint edge preparation is not needed. 3oxide removal prior to welding is unnecessary. 4the procedure can be automated and carried out in all positions [5]. number of researchers was comparative between fsw and mig welding for many aluminum alloys. for example, mustafa kemal kulekci and et. al. [6] was study the mechanical this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ moneer hammed tolephih al-khwarizmi engineering journal, vol. 7, no. 2, pp 22 35 (2011) 23 properties of welded joints of en aw-6061-t6 aluminum alloy obtained with fsw and mig welding. c. hamelton and et. al. [7] was compare the mechanical performance of 6061-t6 corner welds produced through the fsw and mig welding and correlated the tensile properties and fracture characteristics with the weld microstructure. zhou carzhi and et. al. [5] was study the fatigue properties of 5083 al-mg alloy welded by single pass fsw and double pass mig welding, and compared between them. while gr bradley and mn james were studied the geometry and microstructure of mig and fs welded aluminum alloy 5383-h321 [8]. r. s. mishra et al. had found that the heat affected zone haz has the lowest strength due to significant coarsened precipitates and the development of free precipitates zones (fpzs) [9]. s. r. ren et al. found that for fsw both tool rotation rate and travel speed exert a significant effect on the thermal input and mechanical properties, where the input heat increased with increasing of tool rotation rate in 6061al-t6, 1050al and 6063alt5, and they found that the fracture of fsw of heat treatable aluminum alloys usually occurs in the haz, i.e. the softest zone in the fsw joints due to significant coarsening of the precipitates while the variation in the rotation rate did not change the fracture mode [10], and that match to g. raghu babu [11]. m. a. sutton et al. explain that as one travel from the crown to the root of the fsw, the grain size deceases, most likely due to the higher heat input near the crown that causes additional grain growth in this region [12]. while the porosity and kissing bond type defect in the stirred zone will affect the quality of the joint. [13]. terry khaled observed that fsw temperatures arrival to the nugget zone nz and parts of the thermo mechanically affected zone tmaz, will cause at least partial dissolution of the hardening phases. ordinarily, therefore, some softening within the nz should be expected in heat treatable alloys that were welded in t-tempers. some grain coarsening and softening could also take place in the haz [14]. in this study, fsw and mig processes are experimentally compared using the output results obtained from mechanical tests and metallurgical examination performed on the welded joints of aa7020-t6 aluminum alloy. the main objectives were assessed to distinguish between those operational parameters ( for fsw were rotational spindle speed and feed, while for mig the parameters were the current, argon gas flow and welding speed) that influence the magnitudes of some mechanical properties of the joined metals in comparing with the base metals properties. 2. experimental work the material used in this work was aa7020t6 (al-mg-zn) aluminum alloy. a piece of this alloy was analyzed to find its chemical composition as shown in table (1) by spectrometer device in al-nasser mechanical industries company and compared with the standard value. the welded plates were (200 mm) in length, (100 mm) in width, and (5 mm) in thickness as shown in figure (1). the actual mechanical properties are given in table (2). table 1, chemical composition of aa7020-t6 al-alloy (wt %) [26]. standard value actual value si ≤0.35 0.24 fe ≤0.40 0.27 cu ≤0.20 0.10 mn 0.05 – 0.5 0.08 mg 1 – 1.5 1.23 zn 4 – 5 4.16 ti 0.08 0.03 cr 0.10 – 0.35 0.15 al bal. bal. fig.1. shape and size of the aa7020-t6 aluminum alloy square butt joints used for welding processes. (all dimensions in mm). this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ moneer hammed tolephih al-khwarizmi engineering journal, vol. 7, no. 2, pp 22 35 (2011) 24 table 2, actual mechanical properties of aa7020-t6 alalloy. yield strength mpa (proof stress 0.2%) ultimate tensile strength mpa elongation el.% 356.3 400 10.5 fsw joints were carried out using a high speed steel tool with 15mm shoulder diameter and the insert pin diameter and height were 5 mm and 4.85 mm, respectively, with cone angle 2.5° as shown in figure (2). fsw was carried out at a different tool rotation of 450, 560, 710 and 900 rpm and a different transverse speed of 16, 25 and 40 mm/min by vertical milling machine (hmt milling machine) as shown in figure (3). the tool was rotated counter-clockwise to force softened material towards the root of the weld and to obtain a full joint at the root of the weld. the butted plates were clamped on a carbon steel backing plate as shown in figure (3). the rotating tool was fixed to the spindle of the milling machine and tilted 2.5º away from the spindle’s travel path. in the fsw procedure, firstly, the surface of the work-piece brought into contact with the shoulder and insertion of the rotating fsw tool was stopped. at this stage, to generate the required pre-frictional heating. then the rotating tool was moved along the joint line. the rolling direction of the plates was the same as of the direction of the weld run. single-sided welds were applied to the plates. typically, the surface appearance of fsw was a regular series of partially circular ripples, which point towards the start of the weld. these ripples were essentially cycloid and were produced by the final sweep of the trailing circumferential edge of the shoulder during traverse. the surface color of fsw was silvery-white for studied material. another set of the al alloy plates was butt welded (single pass for each side) using the mig process. the plates were cleaned before the mig welding procedure with a scraper and acetone. in the mig welding process, a suppermig-460 type semiautomatic welding machine was used for welding the plates (as shown in figure 4) with the parameters of (207 a) current and (23 v) voltage, er5356 filler (chemical composition show in table 3) of 1.2 mm diameter with a welding speed of (10 mm /sec) was used to carry out the mig welds. in the mig process, shielding was provided by argon gas at a flow rate of (16 l/min). fig.2. the present fsw tool geometry (all dimensions in mm) [9]. fig.3. vertical milling machine with carbon steel fixture used for securing fsw samples. fig.4. supermig-460 semiautomatic welding machine. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ moneer hammed tolephih al-khwarizmi engineering journal, vol. 7, no. 2, pp 22 35 (2011) 25 table 3, standard chemical composition of er5356 welding wire [27]. mg 4.5 – 5.5 % mn 0.05 –0.20 % si 0.25 % max br 0.0008 max ti 0.06 –0.20 % cu 0.10 % cr 0.05 –0.20 % zn 0.10 % fe 0.4 % al bal. to evaluate and compare the mechanical properties of the joints obtained with fsw and mig processes, tensile, three points bending and microhardness tests were performed on welded joints. the fsw and mig processes were also compared for the main metallurgical features. the tensile test specimens were machined out according to (astm b557m) and tested with (zwick/roell 100kn) tensile machine at room temperature and constant loading speed (5mm/min). the specimens of the welded plates that joined with fsw and mig processes were taken in traverse direction of weld line. three points bending test specimens were machined according (asme qw-462) while the test carried on fristschi gumbh bending machine. vickers microhardness tests were performed on welded joints according (astm e384) with (50 g) load to compare and assess the hardness distribution of the fsw and mig welding by using zwick/roell microhardness machine. both of the processes were also compared for the main microstructural features after the specimens prepared according (astm e3) standard procedure and using nikon microscope. 3. results and discussion aa 7020-t6 aluminum alloy is seems to be extremely weldable by friction stir welding, since defect free welds were fabricated from the alloy under most welding conditions. four rotational speeds (450, 560, 710 and 900 rpm) was used with three travel speeds (16, 25, and 40 mm/min) to study the effect of welding parameters on the mechanical properties and microstructure feature. the results of transverse tensile test are summarized in table (4). in general, both yield strength and ultimate tensile strength were reduced in the welded area compared with that of the parent material, due to a combination of dissolution, coarsening and reprecipitate of strengthening precipitates during fsw [9], or localized deformation [10]. . . table 4, tensile test results for aa7020-t6 aluminum alloy fsw. welding eff. % utsw/utsb el. %average uts (mpa) average σy (mpa) 0.2 offset travel speed (mm/min) rotation speed (rpm) —10.5400356.3parent materials 694.45277248.516450 755.2529924325 633.65252.5241.540 583.2523122016560 81532324525 744.6296.5257.540 805.8318244.516710 826329252.525 744.25295.5266.540 796316.525716900 857.334024725 55321820340 this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ moneer hammed tolephih al-khwarizmi engineering journal, vol. 7, no. 2, pp 22 35 (2011) 26 the first set of welding parameters using rotation speed (450 rpm) with different travel speed (16, 25 and 40 mm/min) show that the best ultimate tensile strength and elongation can be achieved at (25 mm/min) travel speed. this investigation was repeated for other rotation speeds (560, 710 and 900 rpm). figure (5) shows the relationship between the uts and rotational speeds at different travel speeds and figure (6) shows the relationship between the uts and the travel speeds at different rotational speeds. from the two figures it can be found that the optimum combination of rotation speed and travel speed was occurred at (900 rpm) and (25 mm/min) that gives 85%welding efficiency for 5 mm thick aa7020-t6 aluminum alloy. it is believed that, to obtain high quality fsw welded joints with high mechanical properties, i.e. high welding quality; the main welding parameters (rotation speed and travel speed) must be carefully selected to balance the effect of each parameter on the amount of heat input during stir welding. . fig.5. relationship between uts and travel speeds at different rotational speed. fig.6. relationship between uts and rotational speed at different travel speeds. from the shape and location of the tensile specimens fracture shown in figure (7) the following observations can be made. first, most of the fsw joints failed at heat affected zone (haz) on the advancing side which has the lowest strength due to significant coarsened precipitates and the development of free precipitates zones, these results conform to [9], [10] and [11] and [12]. second, failure occurred in a plane nearly perpendicular to the tensile axis. third, for the same travel speed, the variation in the rotation rate did not change the fracture mode 0 100 200 300 400 200 400 600 800 1000 rotational speed (rpm) u t s ( m p a) 16 mm/min 25 mm/min 40 mm/min 0 100 200 300 400 10 20 30 40 50 travel speed (mm/min) u t s ( m p a ) 450 rpm 560 rpm 710 rpm 900 rpm this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ moneer hammed tolephih al-khwarizmi engineering journal, vol. 7, no. 2, pp 22 35 (2011) 27 and this conforms to [10]. fourth, the fracture surface of specimens with high elongation and best welding quality has dark section similar to the fracture surface of the parent material (, which mean that the welding parameters caused sufficient heat to produce successful joints. another fracture surface can be observed in specimens that of low elongation and welding efficiency have bright section that mean there is a sudden fracture occurred due to insufficient heat input during the fsw. it can be said that welded joints of higher ductility (elongation percent) showed ductile fracture, while that of lower ductility showed brittle fracture during the tensile testing. fig.7. fracture surface of parent material and welded joints. the results in table (4) show that the welding efficiency increased from 75-85% when the rotation speed increases from 450-900 rpm at constant travel speed (25 mm/min). the results of face and root bending test were summarized in table (5) below: the results of bending test are conducted in accordance with the tensile test results, which means, that the best bending force values were achieved at (25 mm/min) travel speed for all rotational speeds. no cracking was observed in bend test of the joints in both test conditions, i.e. with the weld root and face as shown in figure (8). the only exception to that was the specimen welded at travel speed of (40 mm/min) and rotation speeds (450 and 900 rpm), which show crack in the bend test. this is apparently due to the presence of significant porosity and kissing bond type defect in the stirred zone of this joint, and that conform to [13]. table 5, bending test results for aa7020-t6 aluminum alloy fsw. bending load n (root) bending load n (face) travel speed (mm/min) rotation speed (rpm) 11400 11400 bm 9500 10450 16450 10070 10260 25 9120 9120 40 9120 10070 16560 10640 11020 25 10260 10450 40 10070 10450 16710 10830 11020 25 8360 10640 40 10640 11020 16900 11020 11020 25 9120 10450 40 this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ moneer hammed tolephih al-khwarizmi engineering journal, vol. 7, no. 2, pp 22 35 (2011) 28 fig.8. face and root bending specimens. . fig.9. microhardness distribution of the welded area at 900 rpm (2.5mm under surface). according to the results of tensile and bending tests, we selected the (900 rpm) rotational speed at different travel speeds to study the microhardness distribution at the mid thickness (2.5mm under the surface) in the x-axis direction and along the thickness in the y-axis direction. figure (9) shows the hardness distribution in the x-axis direction at 900 rpm and different travel speeds (16, 25 and 40 mm/min). regarding hardness property, in general the microhardness values in all welding area reduced compared with that of the base metal, this means that the heat generated during fsw caused softening of the welded area due to grain coarsening or dissolution of precipitates and that conform to [14], while some grain coarsening and softening could also take place in the haz the decreasing in the weld hardness can be attributed to the dissolution of precipitates and subsequently the weld cooling rates do not favor nucleation and growth of all precipitates [15]. fsw creates a softened region around the weld center in a number of precipitation-hardening aluminum alloys. the softening is caused by coarsening and dissolution of strengthening precipitates during the thermal cycle of the fsw, and the hardness profile strongly affected by precipitates distribution rather than grain size in the weld [9]. from comparing the hardness distribution for three travel speeds it can be found that the fsw joint welded at high travel speed of (40 mm/min) exhibited higher hardness values than that at the lower travel speed of (16 mm/min), that indicates that the thermal exposure experienced by the former was less than that experienced by the latter and that conform to [10] when welded 6061 alt651. it can be seen from figure (9), that minimum hardness values were recorded in the haz and this explains the fracture location of the tensile specimens. the local material softening occurs in the weld caused by the thermal action of the welding process in particular a localized softening in the haz. the width of the haz in most joints are seem to be extremely small and slightly affected by process parameters, for example the 0 20 40 60 80 100 120 140 160 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 position from the weld center line (mm) m ic ro h a rd n e s s h v 0 .0 5 16 mm/min 25 mm/min 40 mm/min this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ moneer hammed tolephih al-khwarizmi engineering journal, vol. 7, no. 2, pp 22 35 (2011) 29 hardness distribution of the joint welded at (25 mm/min ) did not show any haz and the average hardness across the joint is comparable to that of the base alloy and that conform to [16, 17]. it seems that at 900 rpm (the highest rotational speed used), which will produce the maximum heat input and that leads to maximum ductility result from this heat. at the same time, this speed will cause higher rate of plastic deformation which might cause the practical increase in hardness value. these heat input and plastic deformation caused refining in grain size as compared with the base metal. it is obvious that for the same metal, the finer grains, the higher strength and hardness. this might explain the unexpected results (increase in both hardness and ductility) at the higher rotation speed. figure (10) shows the hardness distribution from top to bottom of the plate thickness at (900 rpm) and (16, 25 and 40 mm/min) travel speeds. from this figure, the following observations can be made. first, the hardness values decrease with decreasing travel speed (for the same previous causes). second, the hardness values were increased from the top to the bottom of the plate thickness as a result of decreasing the heat input and fine grains and that conform to [12]. in summary, the hardness of the base alloy was recorded to be about (147 hv0.05), while the minimum hardness recorded for the haz is about (133 hv0.05) which account about 90% of the base alloy, and minimum hardness recorded for the nz was about (138 hv0.05) which accounts about 94% of the base alloy at (900 rpm) rotation speed and (25 mm/min) travel speed. the contribution of intense plastic deformation and high temperature exposure within the stirred zone during fsw results in recrystallization and development of the texture within the stirred zone and precipitates dissolution and coarsening within and around the stirred zone. optical macroscopic examination was carried out for joints welded at (25 mm/min) travel speed and different rotation speeds (450, 560, 710 and 900 rpm)as shown in figure (11), then the same examination was repeated for joints welded at (900 rpm) and different travel speeds (16, 25 and 40 mm/min) as shown in figure (12). . fig.10. hardness distribution along plate thickness fsw at (900 rpm). . fig.11. macrograph of fsw at 25 mm/min and different rotational speed. 80 90 100 110 120 130 140 150 0 1 2 3 4 5 position from top to bottom of plate thickness (mm) m ic ro h ar d n es s h v 0. 05 16 mm/min 25 mm/min 40 mm/min this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ moneer hammed tolephih al-khwarizmi engineering journal, vol. 7, no. 2, pp 22 35 (2011) 30 fig.12. macrograph of fsw at 900rpm and different travel speed. optical macroscopy revealed that no porosity or other defects (such as kissing bond) exist in the stirred zones of most the joints produced except those welded at 40 mm/min travel speed (that conform with tensile and bending tests results). it can be seen from figure (9) that the variation of welding conditions have a very little effect on the morphology and extent of different regions of the welded area for the alloy 7020-t6 and that conform to [17]. a wine glass profile of the joints was observed in all joints produced depending on the tool geometry. based on the microstructural characterization of grains and precipitates, typical distinct zones have been identified nz (nugget zone), tmaz (thermomechanically affected zone), haz (heat affected zone) and bm (base metal) as shown in figure (13). . . fig.13. microstructure of fsw zone. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ moneer hammed tolephih al-khwarizmi engineering journal, vol. 7, no. 2, pp 22 35 (2011) 31 the base alloy has elongated grains relative to the rolling direction and average grain size about (32µm). intense plastic deformation and frictional heating during fsw result in generation of fine equiaxed grains due to dynamic recrystallization [9, 10, 11 12, 13, 14, 18, 19 and 20] and has an average grain size of about (12µm). under some fsw conditions, onion rings structure was observed in the nz. in this work, the onion rings did not present because the tool used in welding was non-threaded pin and that conform to [8] where the non-threaded tools did not produce the onion rings and the rings are the result of periodic variations in crystallographic orientation of grains, or the relative orientation of adjacent grains, and did not differ in grain size. while the small recrystallized grains of the nugget zone contain high density of sub-boundaries, sub-grains and dislocations. the fsw process is associated with the creation of a transition zone tmaz between the base metal and the nugget zone. the tmaz experiences both temperature and deformation during fsw. the tmaz underwent plastic deformation but recrystallization did not occur in this zone due to insufficient deformation strain [9, 12, 18, 20, 21, 15 and 22]. however, dissolution of some precipitates was observed in the tmaz due to high temperature exposure during fsw and the extent of dissolution, of course, depends on the thermal effect experienced by tmaz and that conform to [9]. while the size and morphology of coarser precipitates have no significant change but their orientation along rolling direction like in parent metal is absent in tmaz and that conform to [15]. next to the tmaz is the haz which received no plastic deformation but has only subjected to thermal exposure and therefore the original elongated grain structure of the base alloy is retained with an average grain size (18μm), although strengthening precipitates may overage and coarsen leading to degradation of mechanical properties of this region [9, 12, 15, 17, 20, and 22] which are connected to the location of fracture in tensile test and the lower hardness values were achieved in the haz. selecting an optimal welding procedure for mig welding is important because the optimal procedure ensure weld quality and reliability of welding process while enhancing productivity through elimination of rework. in this work, selecting the welding process, choosing the welding consumable and optimizing the welding parameters are depending on handbooks and manufacturing companies recommendations based on large amounts of empirical data, in addition to the previous studies. table (6) summarized the tensile and bending test results of mig welded aluminum alloy aa7020-t6. in general the yield strength, uts and elongation of the joints were reduced as compared with that of the base metal and that conform to [7, 23, 24 and 25]. the welding efficiency reached 58% as compared with the parent metal and that conform to [23] who achieved 57% welding efficiency when welded 7020-t6 aluminum alloy, while [24] reached 60% welding efficiency when welding 7020/ meal matrix composite reinforced with al2o3, [7] reached 60% when welding 6101-t6 and [25] reached 60% when welding 6082-t6. . table 6, tensile and bending tests results for aa7020-t6 mig welding welding eff. % el. %average uts (mpa) average σy (mpa) 0.2 offset —10.5400356.3bm 586232156mig bending load n (root) bending load n (face) 1140011400bm 89309500mig due to the high temperature required for fusion welding, the haz region was large as well as and the subsequent melting and solidification that occur, voids are common defects found in fusion welds. the presence of voids in the mig welds contributes to the reduced mechanical properties and poor elongation observed during testing. the tensile specimens had failed at the weld metal with sudden fracture without reduction in area or necking. the fracture surface section shown in figure (14). bending test results show that the bending load was reduced as compared with that of the base alloy but did not show any crack in the produced joints fig.14. fracture surface of tensile specimens welded by mig process. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ moneer hammed tolephih al-khwarizmi engineering journal, vol. 7, no. 2, pp 22 35 (2011) 32 hardness distribution in two axes was recorded. figure (15) shows the hardness distribution at the mid-thickness in the x-axis direction. in general the hardness values of the weldment were reduced as compared with the base alloy. the minimum hardness value was recorded in the weld metal which was about (70 hv0.05) and that conform to the tensile test result, while hardness value in the haz was about (100 hv0.05), this value was larger than in the weld metal but lower than of the base alloy which is about (147 hv 0.05). figure (16) shows the hardness distribution along the thickness in the y-axis direction. from this figure it can be shown that the largest reduction in hardness occurs at the point when the two welding passes intersect about (70 hv0.05) due to high heat input and grain growth in this region. . fig.15. microhardness distribution at the mid-thickness (2.5mm under surface). figure (16) microhardness distribution along plate thickness for mig welding. from the macrograph, the weld metal, haz and variations in grain geometry are evident. the microstructure examination shows large variations in grain size and geometry between the welding zones due to temperature gradient as shown in figure (17). this figure shows that the grain in weld metal tended towards an equiaxed shape with an average size about (37µm), while the grains in the fusion zone were generally columnar in shape due to growth from grains in the haz, coupled with direction and gradient of thermal conduction experienced. grains in the haz became more elongated as the distance from the weld increased and the influence of the heat was reduced. typical grain sizes in the haz were (56µm) and that conform [8]. from the previous result, the middle zone of the weld metal have the largest grain size and that conform to hardness value at this region and the fracture location of the tensile specimens. 40 60 80 100 120 140 160 10 9 8 7 6 5 4 3 2 1 0 1 2 3 4 5 6 7 8 9 10 position from the weld center (mm) m ic ro h a rd n e s s ( h v 0 .0 5 ) 40 50 60 70 80 90 100 110 120 130 140 1 2 3 4 5 distance from the surface of weldment (mm) m ic ro h ar d n es s (h v 0 .0 5) this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ moneer hammed tolephih al-khwarizmi engineering journal, vol. 7, no. 2, pp 22 35 (2011) 33 fig.17. macro and microstructure features of mig welding. 4. conclusions 1the chemical composition of the weld zone in fsw does not change as compared with mig welding due to the filler that used with mig which influence the chemical composition. 2the fsw produce a high ultimate tensile strength comparing with mig. where in mig welding the maximum ultimate tensile strength of the welded joint is (232 mpa) compared to (400 mpa) of the base alloy, i.e., the loss of strength about (42%), while in fsw the maximum ultimate tensile strength obtained was (340 mpa), i.e., there is a loss of strength about (15%). 3the minimum hardness was recorded in the wm for mig welding of about (70 hv0.05) and the hardness was increased in the haz to about (100 hv0.05), while for fsw joint the minimum hardness was recorded about (133 hv0.05) in the haz and increased to about (138hv0.05) in the nz as compared with (147 hv0.05) for the base alloy. 4the fsw produce higher bending strength than mig where the mig joint has (8930 n) face bending load and (9500 n) root bending load, although fsw joint has (1102 n) face and root bending load in the optimal welding condition, while the base alloy has (11400 n) bending force strength. 5the average grain size in the wm for mig welding was about (37µm) and in the haz was about (56µm), while in nz for fsw was about (12µm) as compared with the base alloy has (32µm). 5. references [1] a. scialap, l. a. c. de filipps and p. cavaliere, "influence of shoulder geometry on microstructure and mechanical properties of friction stir welded 6082 aluminum alloy", materials and design 28, april 2006, pp. 1124-1129. [2] a. ali, x. an, c. a. rodopouls, m. w. brown and p. o'hara, "the effect of controlled shot peening on the fatigue behavior of 2024-t3 aluminum friction stir welds", international journal of fatigue 29, december 2006, pp. 1531-1545. [3] "welding process handbook", klas weman, cambridge, england, 2003. [4] "welding metallurgy", sindo kou, wiley interscience, second edition, 2003. [5] zhou garzhi, yang xirr qi and luan guo-hong, "comparative study of fatigue properties of friction stir and mig pulse welded joints in 5083 al-mg alloy", trans. nonferrous met. soc. china, vol. 15. no. 4, august 2005, pp. 789-794. [6] mustafa kemal kulekci, erdinc kaluc, aydon sik and ozden basktruk, "experimental comparison of mig and friction stir welding processes for en aw6061-t6 (al-mg si cu) aluminum alloy", this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ moneer hammed tolephih al-khwarizmi engineering journal, vol. 7, no. 2, pp 22 35 (2011) 34 the arabian journal for science and engineering, vol. 35, no. 1b, april 2010. [7] c. hamilton, s. dymek and m. blicharski, "mechanical properties of al 6101-t6 welds by friction stir welding and metal inert gas welding", archives of metallurgy and materials, vol. 52, issue i, 2007, pp. 67-72. [8] gr bradley and mn james, "geometry and microstructure of metal inert gas and friction stir welded aluminum alloy 5383h321", university of plymouth, october 2000, pp. 1-78. [9] r. s. mishra and z. y. ma, "friction stir welding and processing", material science and engineering r50, august 2005, pp. 1-78. [10] s. r. ren, z.y. ma and l.q. chen, "effect of welding parameters on tensile properties and fracture behavior of friction stir welded al-mg-si alloy", scripta materialia 56, october 2006, pp. 69-72. [11] g. raghu babu, k. g. k. murti and g. ranga janardhana, "an experimental study on the effect of welding parameters on mechanical and microstructural properties of aa6082-t6 friction stir welded butt joints", arpn journal of engineering and applied science, vol. 3, no. 5, october 2008, pp. 68-74. [12] m. a. sutton, b. yang, a. p. reynolds and r. taylor, "microstructural studies of friction stir welds in 2024-t3 aluminum", materials science and engineering a323, march 2001, pp. 160-166. [13] g. ç am, s. güclüer, a. ç akan and h. t. serindag, "mechanical properties of friction stir butt-welded al5086-h32 plate", journal of achievements in materials and manufacturing engineering", vol.30, issue:2, october 2008, pp. 151-154. [14] terry khaled, "an outsider looks at friction stir welding" ph. d. thesis, july 2005. [15] t. venugopal, k. srinivasa roa and prasad roa, " studies on friction stir welded aa7075-t6 aluminum alloy", trans. indian inst. met., vol. 57, no. 6, december 2004, pp. 659-663. [16] a. barcellona, g. buffa, l. fratini and d. palmeri, "on microstructural phenomena occurring in friction stir welding of aluminum alloys", journal of materials processing technology 177, 2006, pp. 340343. [17] mohamedtahir m. saeed mulapeer zibary, "metallurgical and mechanical properties of some friction stir welded aluminum alloys", phd thesis, university of salahaddin-erbil, 2009. [18] m. cabibbo, e. meccia and e. evangelista, "tem analysis of friction stir-welded butt joint of al-si-mg alloys", materials chemistry and physics 81, 2003, pp. 289292. [19] g. m. xie, z. y. ma and l. geng, "development of a fine-grained microstructure and properties of a nugget zone in friction stir welded pure copper", scripta materialia 57, april 2007, pp. 7376. [20] n. t. kumbhar and k. bhanumurthy, "friction stir welding of al 6061alloy", asian j. exp. sci., vol. 22, no. 2, 2008, pp. 63-74. [21] r. nandan, t. debroy an h. k. bhadeshia, "recent advances in friction stir welding-processing, weldments structure and properties", progress in materials science 53, 2008, pp. 980-1023. [22] p. cavaliere, r. nobile, f. w. panella and a. squillace, "mechanical and microstructural behavior of 2024-7075 aluminum alloy sheets joined by friction stir welding", international journal of machine tools and manufacture 46, september 2005, pp. 588-594. [23] muafaq mehdi salih, "studying the effect of joint design, angle and heat treatment on mechanical properties of the aluminum alloy weldments (7020-t6) by mig process", master thesis, technical college/baghdad, november 2005. [24] j. m. gơmez de salazer and m. i. barrena, "dissimilar fusion welding of aa7020/mmc reinforced with al2o3 particles. microstructure and mechanical properties", materials science and engineering a352, november 2002, pp. 162-168. [25] s. missori and a. sili, "mechanical behavior of 6082-t6 aluminum alloy welds" metallurgical science and technology, vol. 18, 2000, pp.12-18. [26] "properties and selection: non-ferrous alloys and special purposes materials", asm handbook, american society for metals, vol. 2, 1992. [27] "specification for welding rods, electrodes and filler metal", asme, part c, july 1998. . this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ 35 ، صفحة2، العدد 7مجلة الخوارزمي الھندسیة المجلد د طلیفح السعديمنیر حمی 22 )2011( 35 دراسة مقارنة للخصائص المیكانیكیة للحام الخلط األحتكاكي والقوس المحمي (aa7020-t6)بالغاز الخامل لسبیكة األلمنیوم ***زینب وحیدعبداهللا **كاظم مجبل مشلوش * منیر حمید طلیفح السعدي بغــداد/ الكلیـــة التقنیـــة monerht@yahoo.com: االلكترونيالبرید * kadm52@yahoo.com: البرید االلكتروني** zainab.wa83@yahoo.com: البرید االلكتروني*** الخالصة وبطریقة اللحام (fsw)والتي تم لحامھا بطریقة الخلط االحتكاكي (aa7020-t6)لقد تم دراسة الخصائص المیكانیكیة لصفائح من سبیكة األلمنیوم بینت نتائج البحث تفوق الخصائص المیكانیكیة للملحومات المنجزة بطریقة . وكانت النتائج العملیة ذات داللة في المقارنات . (mig)بمساعدة الغاز الخامل وللحام بمساعدة الغاز mpa 340حیث كانت قیمة الشد األقصى لملحومة الخلط االحتكاكي , از الخامل الخلط االحتكاكي على نظیراتھا الملحومة بطریقة الغ وان ادنى قیمة صالدة مایكرویة للحام الخلط االحتكاكي سجلت في المنطقة المتأثرة mpa 400وان قیم الشد االقصى للمعدن االساس ھو mpa 232الخامل وكذلك hv0.05 70حین سجلت ادنى قیمة صالدة مایكرویة للحام بمساعدة الغاز الخامل في المعدن الملحوم وكانت في hv0.05 133بالحرارة وكانت عن قیمة حمل انحناء اللحام بمساعدة الغاز الخامل في حین انخفض حجم الحبیبات في n 2470سجل زیادة حمل االنحناء لملحومة الخلط االحتكاكي بحدود .µm 32في اللحام بمساعدة الغاز الخامل في حین ان حجم الحبیبات للمعدن األساس كانت 37µmوكان 12µmى الخلط االحتكاكي ال this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ د .علاء al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 10, no. 2, p.p. 3248 (2014) comparisons of mechanical properties of sub-mm lead based and lead free based solder using in manufacturing of printed circuits alaa hasan ali department of materials engineering/university of technology sabbatical leave in chemical engineering& materials science department/ michigan state university/ usa email: dr_alaahassan@yahoo.com (received 22 february 2013; accepted 18 june 2014) abstract this study investigates the mechanical compression properties of tin-lead and lead-free alloy spherical balls, using more than 500 samples to identify statistical variability in the properties in each alloy. isothermal aging was done to study and compare the aging effect on the microstructure and properties. the results showed significant elastic and plastic anisotropy of tin phase in lead-free tin based solder and that was compared with simulation using a crystal plasticity finite element (cpef) method that has the anisotropy of sn installed. the results and experiments were in good agreement, indicating the range of values expected with anisotropic properties. keywords: lead-free solder, composite solder, and aging. 1. introduction lead based solders have been widely used in electronic assembly industry for several decades. however due to potential hazards associated with the toxicity of lead affords has been taken to eliminate or replace the tin in consumer products. among these efforts, tin based solders have become the dominant choice for electronic assembly industries. in recent years, there have been many investigations regarding the mechanical properties of the lead-free solders [1, 2]. however there is lack of understanding about the mechanical properties of these alloys. the existing information in the literature are from a different fabrication and testing process which causes variation in microstructures and mechanical properties associated with these microstructures [3]. therefore in order to develop a reliable model to predict the deformation behavior of lead-free solders, a comprehensive understanding of mechanical properties is required. most of the prior studies focus on the tin anisotropy and the effect of this material characteristic on mechanical properties of leadfree solder joints and their behavior during mechanical deformation and thermal processes [4, 5, 6]. there are very few investigations on the statistical variation of mechanical properties of as fabricated lead-free solder balls [1, 7]. therefore further investigations are required to be conducted to provide more insights into the effects of processing parameters and also alloy compositions on the mechanical properties of different solders. the focus of this study is to provide enough statistical data to be able to compare the joint scale mechanical behavior of the lead free solders and different lead based solders to gain insights into the effect of anisotropy associated with the coarse grain microstructure of lead free solders with isotropic properties of lead based solders. mailto:dr_alaahassan@yahoo.com alaa hasan ali al-khwarizmi engineering journal, vol. 10, no. 2, p.p. 3248 (2014) 33 due to the isotropy associated with the polycrystalline microstructure of lead based solder as well as the interaction between different phases ( pb as a soft phase and tin as a hard phase) traditional modeling procedures based upon the isotropic hardening and creep models can be quite efficient in prediction of damage in electronic packages specially in the thermal cycling loading conditions [6, 8, 9]. however use of these methods for prediction of the location of failure is not promising in lead free solders. previous work focus on the variability of solder balls of different alloys and their effect on manufacturing electronic system. additional work ought to be done to improve the scientific understanding variable properties of solder balls for different alloys so the motives of the present study are to give more understanding how the different balls sizes and sn elastic and plastic anisotropy phenomena effect on the strength and ratability of solder joint of manufactured electron system and must be taken into consideration by manufacturer and supplier. 2. crystal plasticity formulation a velocity gradient in plastic deformation in the material coordinate system can be decomposed into a rate of deformation and a spin tensor as: lp=dp+wp …(1) where is the velocity gradient in plastic deformation. and are rate of deformation and spin tensor simultaneously. an elasto-plastic problem is usually defined as a constrained optimization problem aimed at finding the optimum stress tensor and internal variables for a given strain increment. in such a problem, the objective function is defined based on the principle of maximum dissipation and is made of terms describing the incremental release of elastic strain energy and the dissipation due to the incremental plastic work and the constraint is the yield function, [10]. …(2) where is the design variable (stress tensor) to be found, q is a vector containing the internal variables such as strain hardening and kinematic hardening variables to be found, c is the material stiffness matrix, f( , q) is the yield function, and e is the so-called matrix of generalized hardening moduli. one of the solutions to the above problem is the following equation for the plastic rate of deformation, [11]. dp=λ σ σ ∂ ∂ ),( qf …(3) in a crystal plasticity problem, the deformation is defined by several yield surfaces, and the number of yield functions depends on the number of slip systems in a crystal. assuming the validity of the schmid law for the plastic deformation of a single crystal, then for any slip system a yield function can be defined as: ( ) 1 : , −= τ α ασ σα y p qf …(4) the constraints of problem (2) can be combined and replaced by an equivalent single constraint defined as: …(5) where is the critical shear stress on slip plane , and is a matrix showing the orientation of a slip system and is defined by: is the symmetric part of the schmid tensor, , describing the orientation of a slip system, defined as: …(6) where is a unit normal to the slip plane, and is a unit vector denoting the slip direction. the plastic deformation matrix can be expressed as, [11]: …(7) where are the slip rates. and spin tensor, which represents the material axis rotation, can be expressed as: …(8) where matrix is the anti-symmetric part of ,defined as: alaa hasan ali al-khwarizmi engineering journal, vol. 10, no. 2, p.p. 3248 (2014) 34 …(9) using equation 3,5 and 7, it can be shown that during the plastic deformation of a single crystal the slip rate on any slip system could be expressed by, [12]: …(10) where m and are material parameters that control the shape of the single-crystal yield surface, and been shown to have a direct relationship with the stacking fault energy (sfe) of the material as following: …(11) where is the sfe of the material, g is the shear modulus, and b is the magnitude of burgers vector. for most materials m = 1 and parameter is a lagrange multiplier which has been shown to be a measure of the rate of plastic work in a crystal, the generalized schmidt factor can be found for each slip system α by finding the scalar product of the normalized stress tensor (using the frobenious norm) and the schmidt matrix. in order to define the resistance against the shear, hill, [13], and asaro and needleman, [14], proposed the following formulation: …(12) where is the plastic slip rate on the active slip system , and are the components of the hardening matrix are known as the selfhardening moduli while for are known as the latent-hardening moduli. hutchison, [15], proposed the following model for evolution of the components of hardening matrix …(13) here q is the so-called latent-hardening ratio, which is the hardening on a secondary slip system caused by slip on a primary slip system (kapoorand nemat-nasser) [16] and can be measured by the ratio of the latent-hardening rate to the self-hardening rate of a slip system with typical values in the range of 1 < q < 1.4. the parameter q can be considered as 1 for coplanar slip systems and 1.4 for non-coplanar slip systems. there are different kinds of hardening models presented by researchers for the evolution of (so-called self-hardening). one of the most well-known formulations is: …(14) where , a, and are slip system hardening parameters, which are considered to be identical for all slip systems, denotes the initial hardening rate, the saturation value of the slip resistance, and a the exponent describing the shape of the stress-strain yield function. these parameters can be obtained by fitting the model to experimental data. 2.1. calibration of cpfe simulations the crystal plasticity model developed by (zamiri and pourboghrat , [12] ), for fcc metals was used to study tin. firstly, the existing crystal plasticity model was modified in order to account for the more complicated crystal structure of tin. tin has a body centered tetragonal crystal structure with 32 possible slip systems. since not much is known from the literature about the slip activity of tin slip systems, slip resistance or hardening characteristics, a modified crystal plasticity model was used to simulate the deformation of solder balls under shear loading in order to identify the likely active slip systems and hardening properties that allow comparison with experiments. due to its formulation, the crystal plasticity model calculates shear rate for each slip system, allowing the user to identify the most active slip systems for a given increment of plastic deformation. the incremental hardening of slip systems is also a function of the magnitude of shear rates, and hardening parameters. by comparing the simulation results with microscopic and macroscopic measurements, estimates for the hardening parameters of slip systems for tin were identified (darbandi et al., [10]). once these parameters were fitted to a set of experimental dataset, they were no longer modified when the code was used to simulate deformation of tin solder balls under different loadings the finite element analysis was performed using commercial finite element code abaqus. the crystal plasticity material model was implemented using a user material subroutine in )1 1 2(τ alaa hasan ali al-khwarizmi engineering journal, vol. 10, no. 2, p.p. 3248 (2014) 35 fortran (vumat).solid works was used to make the model of the solder balls and abaqus was used to create the finite element mesh with the assignment of the boundary conditions, and building the input parameters for the analysis. the elements are 8-node linear bricks with reduced integration and hourglass control. hourglassing can be a problem with first-order, reduced-integration elements (cps4r, cax4r, c3d8r, etc.) in stress/displacement analyses. since the elements have only one integration point, it is possible for them to distort in such a way that the strains calculated at the integration points are all zero, which, in turn, leads to uncontrolled distortion of the mesh. first-order, reduced-integration elements in abaqus include hourglass control, but they should be used with reasonably fine meshes. hour glassing can also be minimized by distributing point loads and boundary conditions over a number of adjacent nodes. the elastic constants for tin and copper are known and tabulated in tables 1 and 2, respectively. the parameters used for hardening in table 2, were chosen so that they generated trends that are commonly observed in polycrystalline or multi-joint experiments (darveaux et al., [17]) and various single crystal experiments (zhou , bieler, et al., [18] ). table 1, elastic constants (gpa) of tin used in numerical analysis. parameter c11 c22 c33 c44 c55 c66 c12 c13 c23 72.3 72.3 88.4 22.0 22.0 24.0 59.4 35.8 35.8 table 2, hardening parameters of tin for different slip systems used in numerical analysis. parameter a q m 23 ( for all sets) 40 (for all sets) 100 for sets (1,2,5,7) 20 (for all sets) 1.4 1 60 150 for sets (3,4,6,8,9,10) 3. experimental methods tinlead, lead –free solder alloys and pure tin (table 3) [19], were studied, evaluating more than 500 balls that were (420-600) microns in diameter. each ball was individually compressed, to compare the load-displacement deformation behavior of each material. the loading stage with one ball is illustrated in figure 1. table 3, tin, tin-lead, and lead-free solder alloys materials. solder alloys melting temperature ˚c modulus gpa ultimate tensile strength mpa sac305 217 54 36 sn0.7cu 227 43 40 63sn37pb 183 35 37-46 sn3.5ag 221 56 55 30sn70pb 185 32 42.30 sn42bi58 138 11.9 63 sn 231.9 41-45 21.4 alaa hasan ali al-khwarizmi engineering journal, vol. 10, no. 2, p.p. 3248 (2014) 36 3.1. ball compression process the compression process was accomplished using a rheometric solids analyzer instrument model rss 111 (figure 1) at room temperature. fig.1. ball compression fixture within rheometric solids analyzer machine (compliance 6.996e-05 mm/gm.) the compression test methodology was used to obtain the time-dependents material response of compression of a ball shaped sample. each solder ball had a spherical diameter of (420-600) micron , this range of balls diameters was found from loading –unloading processes for each ball solder materials. balls were put in place on the loading platens, and centered approximately close to the loading axis. then the instrument was calibrated to maximum cap of 600 microns ( according to the maximum balls diameter range) and for each ball compression process , the instrument is setting to the reference point command cap to 600 micron , then starting compression test , loading was applied when the loading platen was lowered with simultaneous data acquisition at a rate of 0.01mm/s until a particular displacement was reached, the particular displacement was be fixed in instrument control zone by time interval of 15 sec and a rate of 0.01mm/s . because each ball had a different diameter, the maximum strain imposed varied from sample to sample. the samples were loaded up to a given displacement of (150) microns. as each ball had a different diameter, the load reached at maximum load consequently had a displacement that varied; loading was conducted to a different displacement. 30 samples of each of 8 alloys were investigated. 3.2. aging processes to investigate the effect of grain size on the loading, some alloys were aged to 150 c for 170 hours in a carbolite temperature control oven, type 3508. the microstructure of selected balls before and after aging was investigated after polishing, (but these balls were not deformed). different samples of balls a scanning electron microscope (sem) were taken before aging processes the balls were deformed, aged. aging experiments were performed by placing the solder balls into carbolite temperature control oven, type (3508) at aging temperature for 170 hours. then the balls were slightly polished to remove the oxide layer resulting from to reveal the change in microstructure. scanning electron micrographs of different balls were taken before and after aging process to compare grain growth. 4. results and discussion 4.1. compression test results during the compression processes various deformation behaviors occurred which represent the variation in mechanical property variability for different alloys. this clear in loading– unloading processes and in maximum–loading processes. figure (2) a shows the loading –unloading curves of sac305 alloy chosen from a batch of solder balls supplied by a manufacturer, during compression and unloading process. the load displacements data were shifted along the displacement axis until one of the datum points close to 50 gm was reset to 0 displacement so that all of the curves would have a nearly common initial loading point, to assist comparison. figure (2) b shows the same data without unloading data so that the difference in loading behavior can be more clearly observed. from the known initial and final displacement values, different original ball diameter between (426449) microns were identified. from figure (2) b different deformation behaviors each ball are apparent, particularly with regard to the loading slopes of each ball. balls 15 and 19 show representative value of relatively hard, soft, and in-between deformation behavior. from the load magnitude for these two balls at the same displacement, different load values vary by a factor of 25%. alaa hasan ali al-khwarizmi engineering journal, vol. 10, no. 2, p.p. 3248 (2014) 37 the deformation of sn0.7cu alloy shows in figure (3) a loading –unloading and max.-load deformation in figure (3) b. the loadingunloading deformation behavior shows different slope (different young modulus), balls 16, 14, and 15 show very clear that differences. different maximum load deformation behavior and magnitudes can be shown in figure (3) b, for balls 17, 3, and 13 have different amount of deformation with same amount of load. for 63sn37pb figure (4) a shows the different deformation behavior for loading –unloading slopes and that is clear in different behavior of two groups of balls. figure (4) b shows different maximum load against same deformation magnitude especially for balls 2, 9, 6, and 5. sn3.5ag alloy balls show also different loading-unloading deformation behavior for different balls diameter figure (5) a shows a different unloading slope and that clear for samples 14,2,12, and 1. figure (5) b shows the maximum loading deformation of sn3.5ag balls, as we see for displacement of 0.03 mm (ball 13) needs about 110 gm force ,while for (ball 9) which has less deformation amount of 0.022 mm needs more than 130 gm force for maximum deformation. figures (6) a and b show loading –unloading and maximum load deformation processes for 30sn70pb alloy respectively , variety in unloading slope for some balls like balls 5, 7, 1, and 9 than others. maximum load deformation processes shows large difference deformation interval nearly for same force comparing with others by a factor of 50%. sn42bi58 loading-unloading processes in figure (7) a, the load displacements data were shifted along the displacement axis until all the datum points close to 50 gm so that all of the curves would have a nearly common initial loading point, to assist comparison. all balls have same unloading slope and same deformation behavior .max. load deformation in figure (7) b, shows the difference appears in high deformation after 0.260 gm. loading force, some balls need about 300 gm. for 0.070 mm deformation interval but we find that other balls need about 380 gm. for same deformation interval. sn loading –unloading deformation processes shown in figure (8) a, unloading slope shows that for all balls have same plastic deformation behavior, the difference in interval magnitude comes from the difference in manufacturing balls diameters as received. figure (8) b, shows different maximum load magnitude for same deformation interval can see that clear for balls 16, 6, 11, 14, and 5 for same amount of 0.095 mm distortion need different amount of force from 106.5 gm. to 260 gm. 4.2. aging processes results figures (9-22) show sem images for microstructure of different alloy samples at room temperature and after aging processes at 150˚c for 170 hours. the optical and polarized images of sac305microstructure in figure 9 (a) shows alight region sn-rich phase, participate particles, and small dark particles of cu, while in (b) reveals a crossed polarize picture of as received ball. optical and polarized images in figure (10) a and b after aging process, a shows significantly ball microstructural changes and its stability under isothermal aging condition and coarsening of sn particles. in b the polarized image shows three large regions with different colors (corresponding to no more than three main sn grain orientations). figure (11) a and b shows the sn0.7cu microstructure before aging, greater tin concentration with light appearance and small black particles of cu. figure (12) a and b shows the grain enlargement of sn grains which appear clear in b. optical micrographic and polarize image for 63sn37pb sample before aging are shown in figure (13), bright color of sn-rich grains and grey pb shown by arrows in a, while in b the crossed polarizer picture shows at least two different colors represent the sn grains orientation . figure (14a) shows the change its microstructure after aging process represent by sn grain enlargement and orientation that is shows more clearly in b of different colors of sn grains. figure (15) a and b shows the optical and polrized micrograph for sn3.5ag alloy solder before aging , in a shows the sn grain of light color, while ag3sn participate particles with gray color.in b the polorized image shows the different colors represantive by sn-rich orentation grains. the microstructure changes shown singfictaly in figure (16) a and b after aging process, and at least tow different colors of sn grains can be seen in b. the distribution of sn and pb grains structure of tin-lead alloy 30sn70pb before aging is shown in figure (17) a and b, sn grains with light color and pb-rish with dark color. the microstructure of solder after aging process shown in figure (18) a and b with no scientifically sn grains orientation. alaa hasan ali al-khwarizmi engineering journal, vol. 10, no. 2, p.p. 3248 (2014) 38 figure (19) shows the microstructure images for sn42bi58 alloy before aging process in a as optical and in b as polarized with homogenous distribution of sn and bi grains. after aging process, the microstructure was changed, as we see in figure (20) a and b, sn grains enlargement and orientation was revealed by a crossed polarizer picture in b. pure sn as received before aging is shown in figure (21) a and b, the irregular cross section ball as a result of polishing work and the softened of pure sn ball, in b, t two different colors appear according to the sn grain orientation. figure (22) a and b show the homogenous and enlargement sn grains structure after aging process. 4.3. simulation results simulation approach was done on two of solder materials sac305 as a lead-free solder alloy and the second 30sn70pb as a tin-lead based solder alloy to compare the deformation behavior for each solder. the simulation approach results are represented by two figures (23) and (24). according to the compression deformation results, the different behavior of each material during compression deformation and its effect on variable the properties of solder balls, which interpret the anisotropy grain behavior for sac305, as shown in figures (2) a and b . anisotropy is very strong in sn and has large effect on the reliability , the fracture probability in lead –based solder alloy is different from that in lead-free solder alloys, mostly because of the anisotropy present in tin phase [20]. that is clear in variety in loading –unloading slope and also in the different amount of maximum load for some ball during deformation .this behavior is clear in the microstructure of sac305 before and after aging. the orientation of grain illustrate very clear the anisotropy behavior of sn grain figures. (9) and (10) and also is illustrated in simulation figure (23). when material is formed, the grains are usually distorted and elongated in one or more direction which makes the martials anisotropy. as the microstructure of solder coarsening during the aging process, it is necessary to investigate its influence on the mechanical properties of the solders. the characterization of lead –free solder, especially after isothermal aging, is very important in order to accurately predict the reliability of solder balls, and the grain size and morphology have significant effect on the mechanical properties of sub-mm scale balls. optical micrographs show bright field image of as an received sample , while polarized micrographs reveal a crossed polarizer picture of solder ball, it can be seen that large region with different colors corresponding to main sn grain orientation increase in aging samples. the simulation approach supported the experiments results for sac305 and that is shown in figure (23), the isotropic model is too far from the experimental results showing that isotropic hardening overestimates the hardening .the anisotropy of sn grains in sac305 lead-free solder alloy interpret the different behavior of deformation of balls and its effect on mechanical proprieties like modulus of elasticity, strength, and reliability. simulation results of compression tests for 30sn70pb in figure (24) are showing that the isotropic model matches well with experimental data. alaa hasan ali al-khwarizmi engineering journal, vol. 10, no. 2, p.p. 3248 (2014) 39 a b fig. 2. (a) sac305 loading-unloading and (b) sac305 loading to maximum load. a b fig. 3. (a) sn0.7cu loading-unloading and (b) sn0.7cu loading to maximum load. alaa hasan ali al-khwarizmi engineering journal, vol. 10, no. 2, p.p. 3248 (2014) 40 a b fig. 4. (a) 63sn37pb loading-unloading and (b) 63sn37pb loading to maximum load. a b fig. 5. (a) sn3.5ag loading-unloading and (b) sn3.5ag loading to maximum load. alaa hasan ali al-khwarizmi engineering journal, vol. 10, no. 2, p.p. 3248 (2014) 41 a b fig. 6. (a) 30sn70pb loading-unloading and (b) 30sn70pb loading to maximum . a b fig. 7. (a) sn42bi58 loading-unloading and (b) sn42bi58 loading to maximum load. alaa hasan ali al-khwarizmi engineering journal, vol. 10, no. 2, p.p. 3248 (2014) 42 a b fig. 8. (a) sn loading-unloading and (b) sn loading to maximum load . a b fig. 9. sac305 microstructure images before aging(a-optical image and b-polarize image). a b fig. 10. sac305 microstructure images after aging ( aoptical image and b-polarize image). sn nn cu sn ss sn sn nn sn sn nn sn sn sn nn sn alaa hasan ali al-khwarizmi engineering journal, vol. 10, no. 2, p.p. 3248 (2014) 43 a b fig. 11. sn0.7cu microstructure images before aging ( aoptical image and b-polarize image). a b fig. 12. sn0.7cu microstructure images after aging (aoptical image and b-polarize image). a b fig. 13. 63sn37pb microstructure images before aging(a-optical image and b-polarize image). a b fig. 14. 63sn37pb microstructure images after agin ( a-optical image and b-polarize image). sn nn sn nn sn nn sn nn sn nn sn nn pb nn sn nn sn sn pb sn cu sn cu sn alaa hasan ali al-khwarizmi engineering journal, vol. 10, no. 2, p.p. 3248 (2014) 44 a b fig. 15. sn3.5ag microstructure images before aging (aoptical image and b-polarize image). a b fig. 16. sn3.5ag microstructure images after aging ( aoptical image and b-polarize image). a b fig. 17. 30sn70pb microstructure images before aging (aoptical and b-polarize image) a b fig. 18. 30sn70pb microstructure images after aging (a-optical image and b-polarize image). sn nn sn nn sn nn sn nn sn nn sn nn sn nn sn nn pb pb pb pb ag sn sn ag alaa hasan ali al-khwarizmi engineering journal, vol. 10, no. 2, p.p. 3248 (2014) 45 a b fig. 19. sn42bi58 microstructure images before aging (a-optical image and b-polarize image). a b fig. 20. sn42bi58 microstructure images after aging (a-optical image and b-polarize image). a b fig. 21. sn microstructure images before aging(a-optical image and bpolarize image). a b fig. 22. sn microstructure images after aging (aoptical image and bpolarize image). sn nn sn nn sn sn bi bi bi alaa hasan ali al-khwarizmi engineering journal, vol. 10, no. 2, p.p. 3248 (2014) 46 fig. 23. sac305 compression simulation . fig. 24. 30sn70pb compression simulation. 5. conclusions compression deformation of different metals of tin-lead and lead-free solders and aging processes at 150 ˚c for 170 hours were done in order to get a comprehensive understanding the mechanical properties of the solders during deformation behavior and isothermal aging processes, and from the experimental and simulation results we can conclude the following: 1. loading-unloading deformation processes give good understanding the variety if deformation behavior and its effect on mechanical properties and the relation of maximum load –displacement show clearly interrelation between the magnitude of elasticplastic deformation with anisotropy phenomena of tin-rich lead-free solder alloys. 2. aging processes at 150 ˚c for 170 hours is suitable for alloy aged –softened and this softening correlated with the growth of relatively large tinrich crystals and the coercing of sn particles. 3. cpfe model can solve the mechanical deformation behavior of materials under compression effect. for sac305 as a leadfree solder the simulation results for compression test showing that since the plastic deformation occurs in a small region of the sample, the difference between differed orientations is observed in large deformation. as is highlighted, the isotropic model is too far from the experimental results showing that isotropic hardening overestimated the hardening. 4. simulation result for tin-lead solder 30sn70pb c compression matches the experimental data are interpreting the homogenous deformation behavior of 30sn70pb balls as a tin-lead solder and support its isotopic phenomenon. 5. the different specification of manufacturing balls as received like sizes and different deformation behavior give us scientifically effect on the mechanical properties which must be taken into consideration by manufacturer and suppliers. 6. the fact that the microstructure remains stable under isothermal aging conditions is beneficial for manufacturing operation when reflow of solder joints. 7. further investigation and study that can be done by reflow same materials and testing as solder joints and compare with present results. acknowledgment the author presents thanks to institute international education & srf for their cooperation and supporting. greatly appreciate and thank to professor andre lee for his supports and cooperation and also to professor tom bieler for his advices and reviewing. the author also thanks professor farhang pourboghrat for his kind cooperation. many thanks to dr. payam darbandi for his kind help in simulation process. also many thanks to quan zhou and yang lu for their assistance in aged samples preparation and testing. alaa hasan ali al-khwarizmi engineering journal, vol. 10, no. 2, p.p. 3248 (2014) 47 6. references [1] andree lee, deep chouduin, and k.n subramiuman , lead-free solders: materials a. reliability for electronics, first edition. edited by k. n. subramanian, (2012), p. 273. [2] r.a. lebenson and c.n. tome, “a selfconsistent anisotropy approach for the a. simulation of plastic deformation and texture development of polycrystals application b. to zirconium alloys, acta metal. mater. 41, 2611 (1993). [3] a.u.telang and t.r.bieler, “the orientation imaging microscopy of lead-free sn-ag a. solder jointsˮ, jom. june (2005), pp. 4449. [4] h.f.zou , z.f.zhany, “ effect of aging time , strain rate and solder thickness on a. interfacial fracture behaviors of sn3cu/cu single crystal jointsˮ , microelectronic b. engineering 87 (2010) 601-609 [5] karl seeling and david suroski, aim, incorporated. [6] p.kumar, z.huang, i. dutta, g. subbarayan, and r. mahajan, lead-free solders: a. materials reliability for electronics, first edition. edited by k. n. subramanian, b. (2012), p. 197. [7] q.k.zhany, o.s.zhu, z.f. zhang, “fracture mechanism and strength-influencing a. factors of cu/sn-4ag solder joints aged for different times, materials science and b. engineering a 527 (2010) 1367-1376. [8] qiang xiao, luu nguyen, william d.armistrong, “aging and creep behavior of a. sn3.9ag0.6cu solder alloyˮ, electronic components and technology conference, b. (2004), pp.1325 -1332. [9] thomas r. bieler, bite zhou, lauren blair, amir zamir, payam darbandi, farhang a. pourboghrat, tae-kyu lee, and kuochuan liu, “the role of elastic and plastic b. anisotropy of sn in recrystallization and damage evolution during thermal cycling in c. sac305 solder joints”, j. of electronic materials, vol. 41, no. 2, 2012, pp. 283-301. [10] p.darbandi, t.r. bieler, f. pourboghrat, and tae-kyu lee, “crystal plasticity finite a.element analysis of deformation behavior in multiple grained lead-free solder b. joints”, journal of electronic materials, vol. 42, issue 2, (2013), pp. 201214 [11] a.zamiri, t.r. bieler, and f.pouboghrat, “anisotropic crystal plasticity finite element a.modeling of effect of crystal orientation and solder joint geometry on deformation after temperature change, j. electron mater. 38, 231 (2009).ˮ [12] a.r.zamiri and f.pouboghrat,” a novel yield function for single crystal based on combined constraints optimization, int.j. plast 26, 731 (2010). [13] r.hill, “generalized constitutive relations for incremental deformation of metal crystals by multislipˮ, j.mech. phys.solids 14, 95 (1966). [14] r.j. asaro and a. needleman,” overview no. 42 texture development and srain hardening in rate dependent polycrystalsˮ, acta metall. 33, 923 (1985). [15] j.w. hutchison,” bounds and selfconsistent cistimates for creep of polycrystalline materials, proc.r. soclond. ser. a139, 247(1976). [16] r. kappor and s. nemat-nasser, ” highrate deformation of single crystal tantalum temperature dependence and latent hardening, scripta mater. 40, 159 (1999). [17] r. darveaux et al., “solder joint fatigue life of fine pitch bgas-impact of design microprocessors, electronic components and technology conference (2005 [18] b. zhou, t.r. bieler, t.-k. lee, and k.-c. liu,” methodology for analyzing slip behavior in ball grid array lead-free solder joints after simple shear, j. electron. mater. 38, 2702(2009) [19] dr.thomas siewert, dr. stephen liu, dr. david r. smith, mr. juan carlos madeni, “database for solder properties with emphasis on new lead-free solders”. national institute of standard and technology &colorado school of mines, february (2002). [20] [20] j.gong, c.liu, p.p.conway, and v.v.silberschmidt,” mesomechanical modeling of snagcu solder joints in flip chipˮ, compute. mater. sci. 39, 187(2007). )2014( 3248، صفحة 2، العدد10دجلة الخوارزمي الھندسیة المجلع م 48 الخواص المیكانیكة لمواد اللحام الحاویة على الرصاص والخالیة منھ والمستخدمة في ةمقارن تصنیع الكارتات األلكترونیة عالء حسن علي الجامعة التكنولوجیة/ قسم ھندسة المواد جامعة والیة میشیكان األمریكیة/ تفرغ علمي في قسم الھندسة الكیمیاویة وعلم المواد dr_alaahassan@yahoo.com :البرید األلكتروني الخالصة خواص االنضغاط المیكانیكیة للسبائك الكرویة للقصدیر المحتوي على الرصاص والخالي منھ باستخدام اكثر من منتركزت ھذه الدراسة على التحقق .كما تم استخدام التعتیق الحراري لدراسة ومقارنة تاثیره على الخواص والبنیة المجھریة، عینة لتحدید التباین االحصائي في خواص كل سبیكة ٥٠٠ ح ظاھرة تباین الخواص اللدنھ والمرنھ لطور القصدیر في السبائك الخالیة من الرصاص ومقارنة النتائج العملیة مع عملیة اظھرت النتائج بشكل واض .باینة للقصدیرالتمثیل باستخدام طریقة العناصر المحددة والتي اظھرت نتائج متقاربة مع النتائج العملیة و اشارت الى القیم المتوقعة من الخواص المت mailto:dr_alaahassan@yahoo.com <4d6963726f736f667420576f7264202d20e5d4c7e320e6c7d3d1c7c120e6dac8cfc7e1e3e4dae336342d203731> al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 14, no. 4, december , (2018) p.p. 6471 effect of using combined square nozzle & winglet with helical tape on thermal characteristics in tube heat exchanger hisham assi hoshi* israa s. ahmed** abdulmunem r. abdulmunem *** *,**,*** department of electromechanical engineering/ university of technolog/ baghdad/ iraq *email: hah_62@yahoo.com **email: israa6179@yahoo.com ***email: abdulmunemraad@yahoo.com (received 19 march 2018; accepted 22 may 2018) https://doi.org/10.22153/kej.2018.05.004 abstract influence of combined square nozzle with helical tape inserted in a constant heat flux tube on heat transfer enhancement for turbulent airflow for reynolds number ranging from 7000 to 14500 were investigated experimentally. three different pitch ratios for square nozzle (pr = 5.8, 7.7 and 11.6) according to three different numbers of square nozzle (n = 3, 4 and 5) and constant pitch ratios for helical tape were used. the results observed that the nusselt number and friction factor for combination with winglets were found to be up to 33.8 % and 21.4 %, respectively higher than nozzle alone for pitch ratio pr=5.8. the maximum value of thermal performance for using combination with winglets was about 1.351 for pitch ratio= 5.8. nusselt number and friction factor correlations from experimental data were developed for turbulent flow. keywords: heat transfer enhancement, thermal performance, turbulators, winglets. 1. introduction thermal performance improvements needed in many industrial applications such as heat exchangers, solar air heater, thermal power generation etc. therefore, heat transfer enhancement methods are often used in a heat exchanger to improve heat transfer coefficient [16]. internal inserts in tubes is one of the most effective approaches for heat transfer enhancement without external power. these techniques lead to the generation of swirling flow which increases the turbulence that is responsible for enhancement heat transfer [7]. numerous investigations using insertion of various turbulators configurations on the improvement of heat transfer were performed. eimsa-ard et al. [8] studied the thermal characteristics through tube by using twisted tape elements. the results reveals that nusselt number was significantly increased with twist ratio. bhuiya et al. [9] studied experimentally the effect of triple helical tapes with different helix angles inserted in tube on heat transfer enhancement. the results showed that the heat transfer increased at the expense of increased blower power. the influence of circular cross sectional rings inserted in tube on the enhancement of heat transfer was studied a numerically by ozceyhan et al. [10]. the results showed that the reduction of the spacing of the rings resulted in an increase in both nusselt number and the friction factor. the effect of triple and quadruple twisted tapes on the improvement of heat transfer through tube was investigated by zhang et al. [11]. the results show that the heat transfer rates and the friction factors in the tubes triple twisted tapes was higher than that of the plain tube. influence of twin twisted tapes inserted through a helical-ribbed tube on heat transfer characteristics for turbulent flow with reynolds hisham assi hoshi al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 6471(2018) 65 number ranging from 6000 to 60,000 was studied experimentally by pongjet p. et. al [12]. the results showed that the twin twisted produces better thermal performance than the plain tube. this work is aimed to study the influence of combined square nozzle and winglet with helical tape on thermal characteristics in tube heat exchanger. 2. experimental set up and procedure 2.1. experimental set the experimental rig of this work is consists of the heat transfer test section, high pressure blower, measurement device, augmentation turbulators. as shown in fig. 1. the test section is made of an aluminum tube of length, inner diameter and thickness are 1350 mm, 45mm and 2.5 mm respectively. flexible electrical wire was attached around the tube as an electric heater to heat the test tube at uniform heat flux condition. the variac transformer was used to control electrical power. the outer surface of the test section and heater coil were insulated by three layers of gypsum, glass fiber tape and asbestos tape to prevent heat transfer to surrounding. eighteen thermocouples type-k with ±0.1 0c accuracy connected to measure surface temperatures. to measure air inlet and outlet temperatures two type-k thermocouples with ±0.1c accuracy were positioned at the entrance and exit of the test section the inlet air temperature was set to (20±1c), all thermocouples connected with selector switch and a digital reader. the orifice meter and inclined manometer were used to measure the air flow rate. six values of air flow rates were conducted to cover reynolds number range from 7000–14500. pressure drop through tube was measured using u-tube manometer. 2.2. heat transfer augmentation devices in this work two types of inserts were used first square nozzle without winglets and with winglets. square nozzle inserts were made of aluminum with dimensions as shown in figure (3). second type of inserts was helical tape having one types of configurations as shown in fig.3. the helical tape made of copper sheet was 1350 mm long, 3 mm tape width (w) and 1.2 mm thick (t) as shown in fig. (3) . all of the combination of square nozzle and helical tape inserts were located in converging square nozzle arrangements with three different pitch lengths as shown in fig (3). 2.3. experimental procedure the electric heater was first switched on and allowed to heat the test tube wall at uniform heat flux condition and the blower was then switched on. firstly the experiment was carried out on the plain tube and then on different insertion turbulators. the air flow rate through the tube was set to a desired value. after reaching the stability condition, the inlet and outlet temperatures of air, pressure drop and the temperature variations along the wall of test section were recorded. 2.4. data reduction the friction factor (�) is given by � = ∆� �� � �� � …(1) heat absorbed by the air (qair) is less by 5 % than the heat provided by the electrical heater (vi) due to the loss of heat to the surrounding ����= ���� = �� ����� − ��)=vi����� (2) the heat transfer by convection from the test tube section can be evaluated as follows: ���� = ℎ!��"# − �$) …(3) the average coefficient of heat transfer can be written as ℎ = %� &'�()*(+) ,�("-*(.) …(4) where: bulk mean temperature �t0) is defined as: �$ = �()1(+) 2 …(5) the average wall temperature is given by �"# = ∑ �# 18⁄ …(6) nusselt number can be obtained by 78 = 9: ;< …(7) the thermal performance (ɳ) is defined as the nusselt number ratio to friction factor ratio of insert to that of a plain tube [13]: ɳ = >�? >�' @? @'� a b …(8) hisham assi hoshi al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 6471(2018) 66 fig. 1. schematic diagram of experimental set. fig. 2. photo of experimental set up . fig. 3. test tube with square nozzle and winglet alone and with helical tape. 3. results and discussion the experimental results of nusselt number and friction factor for plain tube were validated by comparing with those obtained from dittuse boelter correlations and blasius correlation [14].as shown in fig (4) and (5). the comparison shows a reasonable agreement deviation of (5.5 %) and (4.3%) for nusselt number and friction factor. hisham assi hoshi al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 6471(2018) 67 fig. 4. nusselt number versus reynolds number for plain tube fig. 5. friction versus reynolds number for plain tube fig (6) shows the variation of nusselt number versus reynolds number for square nozzle alone with three different pitch ratios inserted in tube. the results show that the reducing of pitch ratios yield a significant increase in heat transfer due to higher turbulence of the flow between the square nozzles. for pr = 5.8, the increase in nusselt number was in the range of 25.18–35.4 % more than the plain tube for the range of reynolds numbers from 7000 to 14500. fig. 6. nusselt number versus reynolds number for nozzel alone fig. 7. nusselt number versus reynolds number for all cases the variations of nusselt number with reynolds number for combination of square nozzles and helical tape inserted with and without winglets are depicted in fig (7). the results show considerable increase of heat transfer for the combination without winglets compared to nozzles alone for all pitch ratio due to turbulence of the flow as well as thin boundary layer which induce by the shape of nozzle and helical tape. the tube fitted with the combination without winglets leading to higher heat transfer than the tube with nozzle alone by around 17.6%, 12.8% and 9.5% for pr = 5.8, 7.7 and 11.6, respectively. also the combination with winglets was more effect on heat transfer than that from combination without winglets. this is because fluid flow through winglets leads to the strengthening of vortices, which makes the flow more turbulent and in turn leads to improved heat transfer. the average nusselt numbers for using the combination with winglets are found to be 17.5%, hisham assi hoshi al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 6471(2018) 68 10.2% and 7.3% more than for the tube with the combination without winglets or to be about 22.8 %, 17.7 % and 11.6 % more than for the tube with square nozzles alone for pr = 5.8, 7.7 and 11.6 respectively. the relations of friction factor with reynolds number value for nozzle alone and all turbulators are depicted in fig. (8) and fig. (9). in the fig. (8) it is observed that the increasing in friction factor values at pr 5.8, 7.7 and 11.6 are about 4.1, 3.9 and 3.5 times above the plain tube respectively. this is because the turbulators increase the surface area and creating more obstruction of the flow. from the fig. (9) it can be observed that the friction factor increases with decreasing pitch ratio. reducing the pitch ratio means increasing the number of nozzle and this leads to increase the blockage against flow stream and thus increasing in the friction factor. the results also showed the combination with winglets gives increase in friction factor at about 23.5%, 16.2% and 10.3 % higher than the combination without winglets and at about 29.4 %, 21.9 % and 16.5 % higher than the nozzle alone for pr 5.8, 7.7 and 11.6 respectively. fig. 8. friction versus reynolds number for nozzel alone. fig. 9. friction versus reynolds number for all cases the variation between the thermal performance factor and the reynolds number for all turbulators used is shown in fig.(10). it is observed that ɳ shows a slight decrease with the increase of reynolds number values but increase with reducing pitch ratio. from this figure, the thermal performance factor of combination is considerably higher than that of the nozzle alone. this indicates that the flow through combination leading to swirls intensity and make the mixing between both boundary and core regions more effective in turn leads to enhanced heat transfer. for the combination without winglets thermal performance factor are found to be 5.54 %, 4.1 % and 3.9 % higher than for the tube with nozzle alone for pr = 5.8, 7.7 and 11.6 respectively. the maximum η of about1.35 is achieved for combination with winglets for pr 5.8 and is higher than the combination without winglets around 10.5% while higher than the nozzle alone at around 15.5%. hisham assi hoshi al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 6471(2018) 69 fig. 10. thermal performance versus reynolds number empirical correlations � = 27ef*g.ijke*g.gl …(9) 78 = 0.0802efg.njkog.lke*g.p2l …(10) where 7000 < re<14500 and ke = 5.8 to 11.6 friction factor and nusselt number correlations by equations (9), (10), were compared with experimental data as shown in figure (11) and (12). the results showed that the maximum deviation is 8% for experimental friction factor data and 10% for experimental nusselt number data. fig. 11. predicted friction factor versus experimental results fig. 12. predicted nusselt number versus experimental results. 4. conclusion the following can be concluded as: 1. the values of both nusselt number and friction factor in tube with combination of nozzle and helical tape with and without winglets were higher than the values in the plain tube. 2. the value of the nusselt number of the tube inserted in the nozzle alone for pitch ratio 5.8 is increased by approximately 5.6 % compare with its value for pitch ratio 11.6. 3. the nusselt number for the tube in which the combination with winglets inserted for pitch ratio 5.88 is 17.5 % higher than the combination without winglets and 33.8% higher than the nozzle alone for the same pitch ratio. 4. the maximum thermal performance is about 1.351 for pitch ratio 5.8 in the case of the combination with winglets and this value is10.5 % higher than the combination without winglets and 15.5% higher than the case of the nozzle alone for the same pitch ratio. notation a surface area, m2 cp specific heat j/kg k d test tube inner diameter, m h coefficient of heat transfer w∕ (m2 k) i current, a l tube length, m k thermal conductivity, (w/m k) m mass flow rate ∆p pressure drop, pa pr pitch ratio hisham assi hoshi al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 6471(2018) 70 pr prandtl number pr= (µ cp)/k q heat transfer rate, w re reynolds number re= (ρ v d)/µ t temperature, k u working fluid velocity m/s v voltage, v greek symbols ρ density, (kg/m3) ɳ thermal performance subscripts i inlet o outlet p plain t turbulators w wall a air 5. references [1] s. eiamsa-ard, k.wongcharee, p.eiamsaard,c.thianpong, heat transfer enhancement in a tube using delta-winglet twisted tape inserts, applied thermal engineering 30 (2010) 310–318 [2] s.w. chang, k.w. yu, m.h. lu, heat transfer in tubes fitted with single, twin and triple twisted tapes, j. exp. heat transfer 18 (2005) 279–294. 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[13] sombat t, yingyong k, sompol s, pongjet p, heat transfer enhancement in tubular heat exchanger with double v-ribbed twistedtapes.thermal engineering 7 (2016) 14–24 [14] f.p. incropera, p.d. witt, t.l. bergman, a.s. lavine, fundamentals of heat and mass transfer, john-wiley & sons, 2006. )2018( 64-71، صفحة 4د، العد14دجلة الخوارزمي الهندسية المجلم هشام عاصي حوشي 71 استخدام المركب لفوهة مربعة ذو جنيح مع شريط حلزوني على الخصائص الحرارية فيتأثير أنبوب مبادل حراري عم***عبد المنعم رعد عبد المن ** اسراء سعد احمد * هشام عاصي حوشي بغداد/ عراق /الجامعة التكنولوجية ية/هندسة الكهروميكانيكالقسم *،**،*** hah_62@yahoo.com :البريدااللكتروني* israa6179@yahoo.com : البريدااللكتروني** abdulmunemraad@yahoo.com : البريدااللكتروني*** الخالصة تدفق حراري ثابت على تحسين نقل يجنيح مع شريط حلزوني مدرج في أنبوب ذ اتتمت دراسة عملية تأثير اتحاد فوهة مربعة ذ .حيث تم استخدام ثالث نسب خطوة مختلفة للفوهة المربعة وهي١٤٥٠٠إلى ٧٠٠٠الحرارة لتدفق هواء مضطرب ولعدد رينولدز يتراوح من لشريط الحلزونية. ) واستخدامت نسبة ثابتة واحدة ل٣و ٤، ٥ثالثة أعداد مختلفة من الفوهات المربعة وهي ( فقعلى و) ١١٫٦و ٧٫٧، ٥٫٨( على التوالي أعلى من %٢١٫٤و %٣٣٫٨الجنيح وجد أنه يصل إلى ات والحظت النتائج أن عدد ناسلت وعامل االحتكاك لالتحاد مع الفوهة ذ لنسبة ١٫٣٥١الجنيح حوالي اتالتحاد مع الفوهة ذا). كانت القيمة القصوى لألداء الحراري الستخدام ٥٫٨الفوهة وحدها لنسبة خطوة هي ( ). تم تطويرعالقات تجريبية لعدد ناسلت ومعامل األحتكاك للنتائج التجريبية ولجريان مضطرب.٥٫٨خطوة هي ( (microsoft word \307\355\344\307\323 \322\337\355107 -99) al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 14, no. 1, march, (2018) p.p. 108117 building a management system to control the construction claims in iraq inas z. hadi directorate, ministry of higher education and scientific research / baghdad/ iraq email:inasszaki@yahoo.com (received 10 may 2017; accepted 24 august 2017) https://doi.org/10.22153/kej.2018.08.004 abstract the paper deals with claims in construction projects in iraq and studies their types, causes, impacts, resolution methods and then proposes a management system to control the impacts of claims. two parts have been done to achieve the research objective (theoretical part and practical part). the findings showed that the main types of the claims are extra work claims, different site condition claims, delay claims and the main causes of the claims are variation of the orders, design errors and omission, delay in payments by owner, variation in quantities and scheduling errors. the claims have bad impacts on the cost by increasing (10% to 25%) and also on the duration of the project by increasing from (25% to 50%).the negotiation is the main method which is used to resolve the claims in the construction project in iraq. finally, the proposed claims management system is developed to control the causes of the claims during the preconstruction phase and construction phase. keywords: claims, construction projects, controlling, delay, management, system, variation orders. 1. introduction today, projects of construction are the subject of more claims than in any other time. the high competition has forced contractors to bid projects with minimum profits in order to stay in business. in addition to their multiparty nature the projects are becoming more complex and risky. claims commonly arise between the parties to construction contracts (owner, consultant, and contractor). claims in construction project are considered by participants of the project to be one of the most unmanageable and unpleasant events of a project (ho and liu 2004). this can be caused a many problems such as; delays, changes, unforeseen circumstances, insufficient information, and conflicts. claims might be made for loss and expense, extension of time, liquidated damages and so on. the contract should set out what can constitute a claim and how it should be dealt with. there may also be claims associated with the appointment of consultants. the main objectives of this study is to identify the characteristics of claims building projects in iraq including ; types , causes, impacts and proposing an efficient system for managing claims in building projects in iraq. 2. overview of construction claims many researchers had taken place on claims in the construction project and the following are the main researches: ala'a s. shdiefat (2013) study claims causes that related to (owners , engineers , contractors and other ) and also determine the impacts of claims in projects in, the research findings showed that the main causes were the changes related to owner, while the delay by the contractor was the second cause, the inas z. hadi al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 108117 (2018) 109 claims impacts on the cost by increasing 10% to 25% of total cost , and on time by increasing 25% to 50%. according to zaneldin (2006) the construction industry in the united arab emirates is considered the largest single industry, yet, it is also very complex and the most fragmented industry as it involves multidisciplinary participants. in this multidisciplinary environment, claims appear to hinder the completion of construction and cause delays in delivering projects. this research presents the results of a study of the types, causes, and frequency of construction claims in the emirates of dubai and abu dhabi in uae using a data from 124 claims for a variety of projects in the two emirates. the data were analyzed and the results of this analysis along with recommendations on how to reduce/prevent claims in construction are then presented. al-momani (2000), this study is to investigate causes of delays on 130 projects in jordan and to aid the mangers of construction projects in establishing adequate evaluation of the contract award by using quantitative data. the results of this indicated main causes of delay in construction of public projects relate to planners, client changes, climate, site conditions, late conveyances, financial conditions and increment in amount. the presence of these factors has an effect on the completion at the time specified. findings suggested that special attention to factors identified can help industry practitioners by minimize the risk of contract disputes. frank dk. (2010) study the causes of delay in construction projects in ghana and identify the important according to the project participants. thirty-two possible causes of delay were identified. the list of delay causes was subjected to a questionnaire survey for the identification of the most important causes of delay. the results of the study show that the respondents agree that financial group factors ranked highest. the budgetary gathering variables were deferral in respecting installment testaments, trouble in getting to credit and change in costs. materials bunch components are second trailed by planning and controlling elements. wilkinson, (2001. this research about project management companies in new zealand. the major issues confronted were relationship-based. the examination in this paper found that venture administration organizations need to conquer issues in their associations with different experts on the venture group and with the customer. this study discusses the problems by using data collected from a survey to project management companies in the new zealand construction industry and examined how project management companies saw their role, their experiences of managing construction projects and suggestions for improving relationships this examination recommends that the issues confronted by organizations in new zealand are probably going to be worldwide and accordingly any arrangement proposed can be connected to different nations. 3. methodology of work and data collection this part of the study narrates the manner in which the research objective of the study would be illustrated. this section discusses the data collection process, the sampling technique deployed and the data analysis technique to be used in the following steps. data collection generally involves two methods primary data collection and secondary data collection. primary data collection refers to the information which is gathered from the owner's documents. secondary data refers to information that is collected from the respondents; in this case the respondents are project managers of construction projects. the respondents would be given research questionaries’ to fill and this data would be utilized for the purpose of data analysis. data collected, reported and discussed. the questionnaire survey was carried out, the results that have been obtained from processing of questionnaires using statistical package for social sciences spss.finally proposed a management system to control causes and impacts of claims. 4. analysis of existing claims in construction projects in iraq a real data has been collected from existed projects to determine the types, causes, impacts of claims. claims information have been collected includes: project duration, project budget, causes of claims, resolution method for claims and their impacts on the projects time and cost as follows: inas z. hadi al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 108117 (2018) 110 4.1 project a the total budget of the project is 15,000,000,000 id with 2 years original duration. table (4.1) shows the causes of claims which happened in this project and their impacts on project cost and time. table 4.1, list of claims causes with their total impacts in project (a) as submitted by the contractor. claims no. causes of claims amount of claims in(id) as submitted by the contractor amount of claims in (id) as settled amount of claims in (days) as submitted by contractor amount of claims in (days) as settled methods of resolving claims 1 variation orders 3,000,000,000 1,500,000,000 100 100 negotiation 2 owner attitudes litigation 3 design errors and omissions 4.2 project b the total budget of the project is 5,000,000,000 id with 8 months original duration. table (4.2) shows the causes of claims which happened in this project and their impacts on project cost and time. table 4.2, list of claims causes with their total impacts in project (b) as submitted by the contractor. claims no. causes of claims amount of claims in(id) as submitted by the contractor amount of claims in (id) as settled amount of claims in (days) as submitted by contractor amount of claims in (days) as settled methods of resolving claims 1 variation in quantities 1,000,000,000 300,000,000 90 90 negotiation 2 oral change orders 3 design errors and omissions 4.3 project c the total budget of the project is 44,000,000,000 id with 4 years original duration. table (4.3) shows the causes of claims which happened in this project and their impacts on project cost and time. table 4.3, list of claims causes with their total impacts in project (c) as submitted by the contractor claims no. causes of claims amount of claims in(id) as submitted by the contractor amount of claims in (id) as settled amount of claims in (days) as submitted by contractor amount of claims in (days) as settled methods of resolving claims 1 delay in payment by owner 5,000,000,000 2,000,000,000 320 320 negotiation 2 variation orders litigation 3 design errors and omissions inas z. hadi al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 108117 (2018) 111 4.4 project d the total budget of the project is 14,746,450,000 id with 450 days original duration. table (4.4) shows the causes of claims which happened in this project and their impacts on project cost and time. table 4.4, list of claims causes with their total impacts in project (d) as submitted by the contractor claims no. causes of claims amount of claims in(id) as submitted by the contractor amount of claims in (id) as settled amount of claims in (days) as submitted by contractor amount of claims in (days) as settled methods of resolving claims 1 variation in quantities 55,000,000 55,000,000 240 240 negotiation 2 delay in payment by the owner 3 estimating errors 4.5 project e the total budget of the project is 19,300,000,000 id with 660 days original duration. table (4.5) shows the causes of claims which happened in this project and their impacts on project cost and time. table 4.5, list of claims causes with their total impacts in project (e) as submitted by the contractor claims no. causes of claims amount of claims in(id) as submitted by the contractor amount of claims in (id) as settled amount of claims in (days) as submitted by contractor amount of claims in (days) as settled methods of resolving claims 1 delay by the owner 100,000,000 0 120 120 negotiation 2 variation orders mediation 3 oral change order by owner 4.6 analysis of the causes of claims for the studied projects the analysis of the five selected project data showed that the highest frequent repetition of claim causes, as presented in table, (4.6) is (variation orders and design errors and omission). table 4.6, list of claim causes in the studied project. no. causes of claim in construction projects total repetition 1 variation orders 3 2 owner attitudes 1 3 design errors and omissions 3 4 variation in quantities 2 5 oral change orders 2 6 delay in payment by owner 2 7 estimating errors 1 8 delay by the owner 1 4.7 the resolution methods of the claims table below shows the resolution methods for the five projects. the table shows that the owner and the contractor resolved their claims through the negotiation process which is the main method of resolution. table 4.7, repetition of resolution method in the selected project. no. methods of resolving claims total repetition 1 negotiation 5 2 litigation 2 3 mediation 1 inas z. hadi al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 108117 (2018) 112 5. statistical analysis and discussion of tabulated answers the questionnaire was formulated based on the literature review, the questionnaire was sent to a selected number of project parties (owner, contractors, and consultant), and after the questionnaire responses were collected the next step was analyzing the tabulated answers statistically. weighted arithmetic mean and standard deviations were calculated and used to evaluate the responses: 5.1 the sample size and sample characteristics table (5.1) shows the details of research sample table 5.1, research sample types of participants no. of forms send no. of forms responded to owner 45 29 contractor 40 23 consultant 30 19 total 105 71 the characteristics of sample have been identified from the responses of the participants as follows; 1the academic qualification of participants as (45) of respondents holding bsc degree , (20) holding msc degree and (6) holding ph. d. degree. 2the experience level among the paticipants showed that (9) have experiences between (6-10) years , (23) have experiences between (11-15) and (38) have experiences more than 15 years. 5.2 the reliability's analysis of claims the cronbach’s alpha is utilized to appraise the robustness of any research instrument. any value above 0.70 is reliable especially for exploratory study (nunnally, 1978), table (5.1) shows the value of reliability for each causes which considered to be high and appropriate for the study purpose. table (5.2), reliability statistics for the claims causes items cronbach's alpha n of items owner 98% 6 consultant 92% 4 contractor 95% 6 overall 96% 16 reliability statistics for the claims resolution methods items cronbach's alpha n of items overall 86% 5 reliability statistics for the claims types items cronbach's alpha n of items overall 89% 11 5.3 data analysis for types of claims table (5.3) shows the highest type of claims are (extra work claims) with a mean (3.8). inas z. hadi al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 108117 (2018) 113 table (5.3), ranking for the types of claims 5.4 data analysis for causes of claims tables (5-4) to (5-6) shows the ranking of the causes of claims which is related by the (owner, consultant, contractor). a. owner table (5.4), ranking for the causes related to the owen b. consultant table (5.5), ranking for the causes related to the consultant ranking std. deviation mean n causes related to consultant no 3 1.35163 3.8 74 estimating errors 1 2 1.21275 3.8 74 scheduling errors 2 1 1.02034 4 74 design errors 3 4 1.39736 3.7 74 poor written contracts 4 c. contractor table (5.6), ranking for the causes related to the contractor ranking std. deviation mean n causes related to contactor no 1 1.12130 4.0 74 variation in quantities 1 3 1.46191 3.5 74 subcontractor problems 2 2 1.26848 3.7 74 delay caused by owner 3 5 1.32592 3.09 74 contractor financial problems 4 4 1.25173 3.4 74 bad quality of contractor's work 5 6 .86693 1.6 74 changes in material , labor and machinery costs 6 5.4. data analysis for resolution methods of claims table (5.6) shows the resolution methods. the table shows that the owner and the contractor resolved their claims through the negotiation process. ranking std. deviation mean n types of claims no. 8 1.26087 3.1 74 contract ambiguity claims 1 2 1.32529 3.6 74 delay claims 2 6 1.44375 3.4 74 acceleration claims 3 4 1.28125 3.5 74 changes claims 4 1 1.36817 3.8 74 extra work claims 5 7 1.41924 3.2 74 different measurements pricing claims 6 3 1.24074 3.5 74 different site condition claims 7 5 1.28414 3.4 74 damage claims 8 11 1.43352 2.5 74 negligence claims 9 9 1.31716 3.1 74 termination claims 10 10 1.60709 2.7 74 inefficiency and disruption claims 11 ranking std. deviation mean n causes related to owner no 3 1.39736 3.7 74 delay caused by owner 1 2 1.30927 3.8 74 changes orders 2 6 1.39444 3.02 74 inducements changes orders by owner 3 1 1.08991 4.1 74 delay in payments by owner 4 4 1.21906 3.4 74 termination of contract 5 5 1.31723 3.06 74 planning errors 6 inas z. hadi al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 108117 (2018) 114 table (5.7), ranking of resolution method of the claims 5.6. data analysis for impacts of claims tables (5.7, 5.8) and figure (5.1, 5.2) show the effects of claims that caused the project cost and time to increase. table 5.8, percentage of claims impact on the project cost increase of project completion cost classes n % less than 10% 17 0.22973 from (10%-25%) 33 0.445946 from (25%-50%) 15 0.202703 from (50%-75%0 6 0.081081 from (75%-100) 3 0.040541 more than 100% 0 0 sum. 74 1 table 5.8, percentage of claims impact on the project time a claims increase project time to classes n % less than 10% 16 0.216216 from (10%-25%) 21 0.283784 from (25%-50%) 23 0.310811 from (50%-75%0 6 0.081081 from (75%-100) 5 0.067568 more than 100% 3 0.040541 sum. 74 1 fig. (5.1): percentage of claims impact on the project cost fig. (5.2): percentage of claims impact on the project time. 6. proposed of claim management system for construction projects management system of claims is proposed to have efficient procedures for minimizing the claims impact (cost and time), the proposed management system has been divided into two stages (preconstruction phase and construction phase) which are shows in figure (6.1) and (6.2). 6.1 management system during the preconstruction phase this phase will be achieved by the following steps: 1. owner must select a qualified consultant (the consultant choosing should not depend on lower price. 2. consultant must review the contract documents in related to specifications, drawings, designs; bill of quantity .the aim of this revision is to identify any ambiguities in contract documents. 3. consultant should meet the owner for reviewing his needs and orientations. 4. consultant has to prepare full documents for changes (addition and omissions). moreover he has to provide final set of modified contract documents to come out with final impacts of changes on project completion cost and duration. 5. owner has to give his approval for the new cost and duration. 6. the qualified based selection qbs should be a basic procedure in selecting the qualified contractor, both of performance and price should be the base of selecting the contractors. ranking std. deviation mean n method of resolving claims no 1 1.15865 4.0 74 negotiation 1 3 1.26175 3.6 74 mediation 2 2 1.20163 3.6 74 dispute adjudicatio n boards 3 5 2.73608 3.4 74 arbitration 4 4 1.44375 3.4 74 litigation 5 inas z. hadi al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 108117 (2018) 115 6.2 management system during the construction phase this phase will be achieved by the following steps: 1. consultant has to establish a documentation center. the documentation center is keeping all transaction and correspondence between the project parties. 2. the contractor has to assign a project manager; the project manager responsibility is to assign a construction manager cm, the cm responsible for mange, claims, variation orders, and any technique issues related to works. 3. the contractor should then notify both of the owner and the consultant about the causes of any claims, if the contractor fails to notify the owner and the consultant, he will then lose his right for any compensation. 4. the construction manager shall prepare all the documents of claim. 5. contractor has to update the information about the claim through his project manager and cm. 6. engineers have to analysis documents of claims with contractors of the project and cm. 7. if the contractor accepted the decision of the engineer, a copy should sent to the owner to paid and if not the claim then goes through any method of resolution. fig. (6.1): claims management system during the preconstruction phase inas z. hadi al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 108117 (2018) 116 fig. (6.2):claims management system during the construction phase 8. conclusions the main types of claims in construction projects in iraq are (extra work claims, different site condition claims, delay claims, changes claims, and damages claims) , and this types of claims caused by many causes which are the main five causes of claims in construction project in iraq are (variation orders, design errors and omission, delay in payments by owner, variation in quantities, scheduling errors). the main method which are used to resolving claims in construction project in iraq is the negotiation method. there is an impact of claims on the project cost between (10%-25%) and on the project time between (25%-50%) and a claim management system should proposed to have efficient procedures for minimizing the claims impact (cost and time) during (preconstruction phase and construction phase) to reduce the claims in construction project in iraq. 9. references [1] al-momani a., (2000),”construction delay: a quantitative analysis”, international journal of project management, volume 18, issue 1. [2] fidic see international federation of consulting engineers. [3] fugar, frank dk1; agyakwah-baah, adwoa b, (2010),”delays in building construction projects in ghana”, australasian journal of construction economics and building, the volume 10 issue 1/2 (2010). [4] ho, s p and liu, (2004),”analytical model for analyzing construction claims and opportunistic bidding”. journal of construction engineering and management, 130 (1), 94104. [5] shdiefat a., (2013),” evaluation of claims management, causes, impact and resolution in building projects in jordan” , jordan, university of isra ,april ,2013. [6] wilkinson s., (2001),”an analysis of the problems faced by project management companies managing construction projects”, engineering, construction and architectural management issn: 0969-9988. [7] zaneldin e.,(2006),”construction claims in united arab emirates: types, causes, and frequency”, international journal of project management united arab emirates university, po box 17555, al-ain, united arab emirates. )2018( 108-117 ، صفحة1د، العد14دجلة الخوارزمي الهندسية المجلم ايناس زكي هادي 117 العراقأعداد برنامج ادارة للسيطرة على التعويضات الحاصلة في مشاريع البناء في إيناس زكي هادي وزارة التعليم العالي والبحث العلمي /دائرة االعمار والمشاريع /قسم المشاريع inasszaki@yahoo.comالبريد االلكتروني: الخالصة ق المتبعة لحلها ومحاولة ائيتناول هذا البحث دراسة التعويضات (المطالبات) في مشاريع البناء في العراق ودراسة انواعها واسبابها وتأثيراتها والطر ،, تم االستناد في هذه الدراسة على الجزء النظري والعملي التأثيرات الحاصلة نتيجة المطالبات (زيادة الوقت والكلفة )دارة لغرض التقليل من االاعداد نظام اق هي (مطالبات االعمال االضافية، مطالبات اختالف ظروف موقع العمل،ع المطالبات الحاصلة في مشاريع العراان نتائج هذه الدراسة اظهرت ان اهم انو اختالف في ،تأخير في الدفعات المالية من قبل المالك ،اخطاء في اعداد التصاميم ،مطالبات التأخير ) وان اهم اسباب هذه المطالبات هي (االوامر الغيارية ة في كلف المشاريع تصل ان المطالبات في مشاريع البناء في العراق اظهرت تأثيرات سلبية من حيث زياد شروع ).اخطاء في برمجة الم ،كميات االعمال هي الطريقة الغالبة في تواظهرت النتائج ان طريقة المفاوضات كان، %٥٠الى %٢٥وزيادة في المدة الزمنية للمشروع بين %٢٥الى %١٠بحدود من مشاريع البناء في العراق. حل المطالبات في مشاريع البناء ومن خالل ما ورد اعاله تم اعداد نظام ادارة للتقليل من تأثيرات المطالبات في al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 2431 (2014) experimental investigation on the emission characteristics of a dual – fuel micro gas turbine by injecting ethanol into compressor inlet air abdul satar j. al-saraf* suhad a. r. al-jumaily** * , ** department of machines and equipment engineering / university of technology * e-mail: dr_asjsaraf@uotechnology.edu.iq ** e-mail: s_jumaily@yahoo.com (received 10 october 2013; accepted 28 january 2014) abstract pollutants generation is strongly dependant on the firing temperature and reaction rates of the gaseous reactants in the gas turbine combustion chamber. an experimental study is conducted on a two-shaft t200d micro-gas turbine engine in order to evaluate the impact of injecting ethanol directly into the compressor inlet air on the exhaust emissions. the study is carried out in constant speed and constant load engine tests. generally, the results showed that when ethanol was added in a concentration of 20% by volume of fuel flow; nox emission was reduced by the half, while co and uhc emissions were almost doubled with respect to their levels when burning conventional lpg fuel alone. keywords: alcohol gas turbine, renewable fuels, exhaust emission control, inlet cooling. 1. introduction the increasing awareness towards environment protection and peak load response is accredited in the development of gas turbine system. gas turbines use large amounts of petroleum-based fuel and cause significant air pollution; nevertheless, they play a very important role in minimizing greenhouse gas emissions as they typically burn lower carbon fuels compared to other types of combustion-based power generation and mechanical drive applications [1]. the primary pollutants from gas turbine engines are nitrogen oxides (nox), carbon monoxide (co), and to a lesser extent, volatile organic compounds (voc). particulate matter (pm) is also a primary pollutant for gas turbines using liquid fuels. nox formation is strongly dependent on the high temperatures developed in the combustor. co, voc and pm are primarily the result of incomplete combustion. ash and metallic additives in the fuel may also contribute to pm in the exhaust. oxides of sulphur (sox) will only appear in a significant quantity if heavy oils are fired in the turbine. emissions of so2, are directly related to the sulphur content of the fuel [2]. blending of bio-fuels with fossil fuels is a more economic option to provide renewable power. all of the current liquid bio-fuels used exhibit a lower heating value less than petroleumbased fuel; thereby requiring a step increase in fuel flow of 10 to 50% to deliver the same power output. the emission levels with liquid fuel like kerosene or gaseous like natural gas may be reduced by addition of oxygenated fuels like alcohol. ethanol, hydrous or anhydrous, has already been tested in gas turbines and found to be a more sustainable source of renewable liquid fuel than other bio-fuel crops [3]. bio-ethanol is distributed in sweden as a substitute for petrol and goes by the name of e85 (85 % ethanol and 15 % petrol). it can be tricky to store, because of its miscibility with water and the mailto:dr_asjsaraf@uotechnology.edu.iq mailto:s_jumaily@yahoo.com abdul satar j. al-saraf al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 2431 (2014) 25 low flash point temperature of 13 o c. ethanol is a volatile, combustible, clear and colourless liquid in room temperature and it has a distinct well known smell and taste. ethanol is the most widely used liquid bio-fuel which on 2009, accounted for more than 94 % of the global biofuel production [4]. micro gas turbines can serve as stand-by generators in case of emergency or lack of power production when the national electricity grid like that locally utilized fails to support the growing demand on electricity. micro gas turbines can replace the conventional reciprocating generators those burning the liquid petroleum fuels. the use of the ethanol/lpg fuel mixture in such engines might suppress the pollutants emission and mitigate their environmental impact. this work unlike the proceedings which add ethanol to the conventional petroleum fuel via blending, but, the liquid ethanol here is directly introduced into the inlet air by a separate injection system. thus, this technique has the advantage of avoiding the harmful effects of ethanol on seals and gaskets of conventional fuel system if straight blended with the petroleum fuel. 2. literature survey the concept of using water and alcohol/fuel microemulsions for the purpose of reducing smoke emissions from jet engine was studied in a t-63 gas turbine combustor. the base fuels jp-4 and jp-8 with appropriate surfactants were used to prepare several ethanol and methanol microemulsions in concentrations ranged from 20 to 40%. water microemulsions were also prepared with these base fuels for a range of 15 to 30% water in fuel. these blends increased co and uhc, while nox was reduced when the surfactant did not contain nitrogen. the reduction in smoke correlated with changes in the h/c ratio of the fuel blends. ethanol/fuel blends were most effective in reducing smoke from the standpoint of cost , operational , and systems effects [5]. a blend of ethanol/jet a fuel with concentrations ranging from 25 to 100% ethanol by volume was tested for thrust specific emission indices of co and nox over a range of throttle settings. the nox emission for the ethanol/jet a blends was lower than that of pure jet a due to lower turbine inlet temperature [6]. kerosene/ethanol blended fuel has been experimentally investigated on the micro-gas turbine unit gilkes gt 85/2 with a concentration level up to 25% ethanol [7]. the uhc emission increases with increasing ethanol addition, while the co emission gives the minimum levels in the equivalence ratio range of 0.1 to 0.2, with 10% of ethanol addition. thus, it may be concluded that the ethanol addition in the range of 10 to 15% in kerosene fired gas turbine unit will certainly offer reduced emission levels. general electric (ge) energy’s aeroderivative class of gas turbines has tested ethanol among many other biofuels to evaluate its sustainability as fossil fuels substitute, and its environmental impact [3]. tests indicated a need for 30% increase in fuel flow concerning the combustion chamber and injectors redesign for burning the much lighter fuel. ethanol produces less nox because it burns with a lower flame temperature and it has oxygen available to burn more completely. the study also addressed the hazardous effects of using ethanol which normally contains 2-8% water that may have alkali metals, which are corrosive to the hot gas path of the turbine. ge co. has been contracted by petrobras to convert one of the two units at a power plant near rio de janiero to burn ethanol [8]. a 43.5 mw, lm6000 gas-fired plant is believed to be the first power plant in the world powered by ethanol. after five months of testing sugarcane ethanol, it was found that nox emissions had been greatly reduced, while efficiency and power levels remained the same. the environmental impact of bio-fuels has been evaluated in an academic study showed that when ethanol was used, the nox emissions became half of that with naphtha. but, co2 has increased as the fuel consumption was higher. in general, the study stated that the emissions with ethanol are 48 % of that of diesel; the lowest of any fuel. further, the change to ethanol probably would extend the gas turbines life expectancy with 100 % [4]. it is a common practice to use excess air to control the combustion temperature. but, this excess air can be reduced if methanol vapour reformed by the turbine wasted heat is injected into the combustion gas [9]. this scheme was found superior to control nox generation while keeping the inlet turbine temperature at 1100 o c. the air, as auxiliary medium was replaced with ethanol-water compound steam that produced with waste heat of a capstone c33 gas turbine. ethanol mass flow was increased up to 10% presenting the expected cooling on the inlet temperature. co and uhc levels were increased by 64 and 59% respectively, while nox levels were reduced by 41% [10]. abdul satar j. al-saraf al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 2431 (2014) 26 the current work studies the effect of adding ethanol in concentrations of 10% and 20% by volume to the combustion air, on the nox, uhc and co emissions of a micro gas turbine engine. introducing ethanol prior to the compressor gives enough time for liquid ethanol to vaporize and mix with the compressed air such that ethanol / air mixture is well prepared to react soon after entering the combustor. this technique will certainly reflected on the pollutants emission from the engine. 3. experimental setup 3.1. test rig a rig has been constructed specially to introduce ethanol in the way of the incoming inlet air such that to reduce its temperature in the sense of controlling exhaust gas emissions. the experimental rig shown in figure (1) is mainly a duct that inducing the ambient air inside to pass across the sprayed ethanol source and driving the treated air down to the gas turbine inlet. at the end of the spray chamber, an air atomiser was installed to create a mist of fine ethanol droplets travelling downstream along with the air draught. the ethanol atomiser has an orifice diameter of (1.2 mm), and it is working at a safe pressure of (4 bar). the gas turbine used in this study is a twoshaft t200d micro-gas turbine unit fabricated by didacta italia which specifications are given in the appendix. the combustion chamber burns the lpg gaseous fuel that ignited by a spark plug. ethanol needs to be introduced in such a way that no disturbance is created within the air flow into the unit components. the above task can be satisfied by means of inlet injection as ethanol easily mix and penetrate the bulk flow of air. the attachment of the gas turbine unit with the spraying system is done by adding the “admission box” which encloses the machine inlet matrix to decelerate and separate the non-evaporated droplets escaping out of the treatment duct before entering the unit. the exhaust emissions of the unit have been measured by extracting samples out of the gases leaving the power turbine. the gas analyser used is manufactured by hephzibah co., model airrex hg-540 with measuring range up to 10000 ppm and a resolution of 1 ppm. the analyser equipped with a sampling probe that installed between the power turbine exit and the exhaust silencer. the samples are directed to the processing unit of the analyser which displaying digitally the level of each pollutant on lcd screen. the study comprises the performing of experiments on the micro-gas turbine unit supplied with ethanol/lpg dual fuel at concentrations of 10 % and 20% ethanol by volume. the purpose is to track the changes in nox, uhc and co emission levels as ethanol being sprayed in the intake air of the unit. abdul satar j. al-saraf al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 2431 (2014) 27 1 starting blower 7 exhaust silencer 13 flexible conduit 2 gas generator compressor 8 lpg fuel vessel 14 treatment duct 3 gas generator turbine 9 lpg fuel flow meter 15 ethanol atomiser 4 power turbine 10 combustion chamber 16 compressed air plant 5 dynamometer 11 orifice air flow meter 17 ethanol bulb flow meter 6 exhaust gas analyser 12 admission box 18 ethanol reservoir fig. 1. experimental set-up showing the spraying system attached to the gas turbine. 3.2. testing procedure the tests are initiated with running the machine on the conventional lpg fuel in the sequence described in reference [11]. each test is targeted to evaluate the engine exhaust emissions under the intended operating condition. switching to dual fuel run needs firstly to reduce the lpg flow rate in accordance to the prescribed volume ratio. secondly, the ethanol fuel is to be supplied into the inlet air in the required volume ratio and brought the ethanol vapour into the combustion chamber. nevertheless, this process is very difficult since the two fuels are come from separate streams such that the combustion chamber acts as a mixing box for them. a good approximation is to deliver the two fuels in amounts determined on basis of the heating value to compensate the reduction in the heat liberated due to lower ethanol heating value. however, practically this is not enough because of the unexpected losses accompany the real engine run. slight changes in both fuels flow rates must be done very slowly to keep the volume mixing ratio while attaining the intended condition with the adequate total mass flow of the dual fuel. due to this prolonged complicated process, some deviations from the nominated volume ratios are to be accepted, although, these deviations were actually marginal. the maximum deviation recorded in the worst cases was on the lower limit of nominal 10% ethanol which gave a ratio of 9.74% representing a deviation of – 2.6%. on the other hand, the upper limit of nominal 20% ethanol in dual fuel gave a ratio of 21.2% representing a deviation of + 6.1%. however, all other tests were accomplishing volume ratios with deviation never exceeded %.51 . 4. results and discussion experiments were first conducted to estimate the variation in exhaust emissions with the power turbine speed. these tests were carried out under a constant load of 65% of the engine full load. figure (2) shows the reduction in nox emission with increasing power turbine speed due to the decrease in residence time and better air utilization in combustion chamber. ethanol presence in the air delivered to the combustion chamber will lower the firing temperature such that suppresses the nox formation. the reduction ranked a value of 40.7% for ethanol to liquefied petroleum gas ratio (eth/lpg) of 10%, while for the ratio of 20% the reduction reached 49.7% compared to the pure lpg run. abdul satar j. al-saraf al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 2431 (2014) 28 6000 10000 14000 18000 22000 power turbine speed ( rpm ) 0 20 40 60 80 n o x ( p p m ) load = 65% eth/lpg ratio: 0.0% eth 10% eth 20% eth fig. 2. effect of power turbine speed on nox emission. the opportunity of completing the combustion is less probable when raising the turbine speed due to shorter residence time, and therefore, higher co levels are expected as shown in figure (3). ethanol addition results in lower firing temperature, and hence, lowering the reaction rates which in turn further increases the co emission. for eth/lpg ratio of 10% the average increase in co level was 98.9%, but with a ratio of 20% this increase reached 127.2% over that with normal lpg run. 6000 10000 14000 18000 22000 power turbine speed ( rpm ) 0 50 100 150 200 250 300 350 c o ( p p m ) 0.0% eth 10% eth 20% eth load = 65% eth/lpg ratio: fig. 3. effect of power turbine speed on co emission. 6000 10000 14000 18000 22000 power turbine speed ( rpm ) 0 20 40 60 80 u h c ( p p m ) 0.0% eth 10% eth 20% eth load = 65% eth/lpg ratio: fig. 4. effect of power turbine speed on uhc emission. 25 50 75 100 percent of full load 0 20 40 60 80 n o x ( p p m ) nt = 12000 rpm eth/lpg ratio: 0.0% eth 10% eth 20% eth fig. 5. effect of engine loading on nox emission. for the same reasons as co, the uhc emission is also increases with turbine speed. nevertheless, an additional source of uhc in the exhaust gases comes from the breakdown of evaporated ethanol which fails to be oxidized. the uhc emissions for both the eth/lpg ratios are almost the same for whole turbine speed range. however, at higher speed, the higher the ethanol in fuel mixture, the higher uhc emission was recorded due to excess supply of fuel mixture. figure (4) shows an average increase in uhc of 88.3% for both eth/lpg ratios , but when goes abdul satar j. al-saraf al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 2431 (2014) 29 beyond 16000 rpm, 20% ethanol reached a level of 19.3% higher than that with 10% ethanol ratio. 25 50 75 100 percent of full load 0 50 100 150 200 250 300 350 c o ( p p m ) nt = 12000 rpm eth/lpg ratio: 0.0% eth 10% eth 20% eth fig. 6. effect of engine loading on co emission. 25 50 75 100 percent of full load 0 20 40 60 80 u h c ( p p m ) nt = 12000 rpm eth/lpg ratio: 0.0% eth 10% eth 20% eth fig. 7. effect of engine loading on uhc emission. understanding the impact of engine loading on the dual-fuel gas turbine, requires tests to be conducted at four steps of loading namely, 40, 50, 65 and 90% of the engine full load. those tests were executed to maintain a constant power turbine speed of 12000 rpm. figure (5) shows the variation of nox emission with engine loading. more fuel must be supplied to support the load exerted which in turn leads to rise the firing temperature, as well as, increasing the nox emission. the depreciation in heating value due to lpg substitution with ethanol brings more fuel to be supplied and hence, the firing temperature to be decreased causing the nox emission to reduce. the reduction in nox emissions was 36.8 and 48.6% for eth/lpg ratios of 10 and 20% respectively, both compared to the pure lpg run. increased firing temperature with higher engine loading will promote the reaction rates and less co levels were observed along the loading range. nevertheless, adding ethanol will lower these rates and cause the oxidation process to regress resulting in higher co emissions. figure (6) indicates an average increase in co levels of 95.6 and 138.3% at eth/lpg ratios of 10 and 20% respectively. almost same trends of uhc emission were observed for both eth/lpg ratios when dual fuel was supplied. the average increase in uhc levels over that of pure lpg was 62.7 and 78.5% for 10 and 20% eth/lpg ratio respectively as shown in figure (7). 5. conclusions  when increasing the power turbine speed up to 20300 rpm, nox has reduced by 49.7% for eth/lpg ratio of 20% by volume. but when rising the engine loading from 40 to 90%, the average nox emission was reduced by 48.6% for that ethanol concentration compared to normal lpg run.  co emission was increased by an average of 127.2% when increasing the turbine speed up to 20300 rpm at 20% eth/lpg ratio. however, the load exerted on the engine when elevated to 90% limit gave a rise of 138.3% at the respective eth/lpg ratio over pure lpg run.  uhc emissions where almost the same for both eth/lpg ratios as increasing the ethanol content in fuel resulted in an average increase of 88.3% with respect to lpg normal run along the low and medium speed range. increasing the level of load exerted led to an average of 78.5% increase at 20% ethanol in fuel flow with respect to lpg engine run. abbreviations co carbon monoxide eth ethanol ge general electric co. h / c hydrogen to carbon ratio lcd liquid crystal display abdul satar j. al-saraf al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 2431 (2014) 30 lpg liquefied petroleum gas nox nitrogen oxides pm particulate matters sox sulphur oxides uhc unburnt hydrocarbons voc volatile organic compounds 6. references [1] “the gas turbine: a climate change solution”, online technical reports, www.gasturbine.org. [2] boyce m. p., “gas turbine engineering handbook”, 2nd edition, gulf professional publishing, elsevier (usa), 2001. [3] schornick j.f., “use of biodiesel in the lm packages”, ge aero energy division, houston, texas usa, position paper #54, 2009. [4] kallenberg a., “liquid bio fuels for gas turbines”, master thesis, department of energy sciences, faculty of engineering, lund university, sweden, 2013. [5] naegili d.w., moses c.a., “fuel microemulsions for jet engine smoke reduction”, asme jour. of engineering & power, vol. 105, pp: 18-23, 1983. [6] mendez c.j., parthasarathy r.n., gollahalli s.r., “performance and emission characteristics of a small-scale gas turbine engine fuelled with ethanol/jet-a blends”, aiaa aerospace sciences meeting, 12 th jan., 2012, nashville, tennessee. [7] solanki h., channiwala s., “experimental investigation on emission characteristics of kerosene-ethanol blends type fuel in small gas turbine engine gilkes gt 85/2”, international conference on mechanical engineering, 28-30 dec.2005, dhaka, bangladesh. [8] bevill k., “ ge powers turbines with ethanol in brazil ” , ethanol producer magazine, sept. 23rd, 2010, www.ethanolproducer.com [9] danjou k., yamamoto t., sugiyama h., “enhancing efficiency of methanol fuelled gas turbine”, international symposium on alcohol fuels, 1988, tokyo, japan. [10] jozsa v., “application of bioethanol in gas turbines”, periodica polytechnic, mechanical engineering, vol. 55, part 2, pp: 91-94, 2011. [11] “t200d two-shaft gas turbine unit”, user’s manual and exercise guide, didacta italia, 2001. appendix specifications of t200d twin-shaft gas turbine unit [11] compressor : centrifugal turbines : radial inflow power output : 1.5 kw @ ng/nt : (55000/21000) rpm compressor speed : 60000 rpm max. free turbine speed : 23000 rpm max. overall pressure ratio : 1.3 / 1 max. firing temperature : 700 – 750 o c max. fuel : lpg, 3 g/s max. @ 2 bar max. http://www.gasturbine.org/ (2014) 2431، صفحة 1، العدد10دمجلة الخوارزمي الهندسية المجلعبد الستار جواد الصراف 31 من وحدة توربين غازي مصغرة تعمل بوقود ثاتدراسة تجريبية لخصائص أنبعاث الملو بحقن األيثانول في الهواء الداخل للضاغطة ثنائي **سهاد عبد الحميد الجميلي *عبد الستار جواد الصراف الجامعة التكنولوجية/ قسم هندسة المكائن والمعدات** ،* gy.edu.iq dr_asjsaraf@uotechnolo: البريد األلكتروني* s_jumaily@yahoo.com: البريد األلكتروني** خالصةال تم إجراء . في غرف إحتراق التوربينات الغازية للمكونات المتفاعلةيعتمد تكون الملوثات بشكل كبير على درجة حرارة األحتراق ومعدالت التفاعل . على إنبعاث الملوثاتللضاغطة لتقييم أثر حقن األيثانول مباشرة في الهواء الداخل ثنائي المحور t200dدراسة تجريبية على وحدة توربين غازي مصغرة حجماً في الوقود %20بصورة عامة ؛ أظهرت النتائج أن إضافة األيثانول بتركيز . ريت الدراسة وفقاً ألختبارات ثبوت السرعة وثبوت الحمل للماكنةـأج الى الضعف تقريباً مقارنة بمستوياتها المنبعثة عن إحتراق وقود uhc و coالنصف ، بينما أرتفع إنبعاث كل من الى noxيؤدي الى خفض إنبعاث lpg الغازي التقليدي للماكنة . <4d6963726f736f667420576f7264202d20cdedcfd120e6d3c7e3cd20e6dae1ed31362d203233> al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 14, no. 4, december , (2018) p.p. 1623 study the effect of different percentages of natural (orange peels and date seeds) and industrial materials (carbon and silica) on the mechanical and thermal properties of polymeric reinforced composites haydar abed dahad* sameh fareed hasan** ali hussein alwan*** *,*** department of mechanical engineering / university of technology ** industrial development and research directorate/ ministry of science and technology *email: hayder_abed2002@yahoo.com **email: sameh_fareed@ymail.com ***email: eng.ali83@yahoo.com (received 20 november 2017; accepted 25 april 2018) https://doi.org/10.22153/kej.2018.04.001 abstract mechanical and thermal properties of composites, consisted of unsaturated polyester resin, reinforced by different kinds of natural materials (orange peels and date seeds) and industrial materials (carbon and silica) with particle size 98 µm were studied. various weight ratios, 5, 10, and 15 wt. % of natural and industrial materials have been infused into polyester. tensile, three-point bending and thermal conductivity tests were conducted for the unfilled polyester, natural and industrial composite to identify the weight ratio effect on the properties of materials. the results indicated that when the weight ratio for polyester with date seeds increased from 10% to 15%, the maximum young’s modulus decreased by 54%. when the weight ratio was 5%, the maximum young’s modulus, yield stress and ultimate tensile stress occurred in the polyester with date seeds. the results of tensile and flexural tests showed that the natural composite material has a higher strength than the industrial material. while the results of flexural tests manifested that the maximum improvement in the flexural strength is obtained for orange peels at 5 wt. %, where the maximum increasing percentage is 153.4% than pure polyester. the thermal conductivity of orange peels decreased to the half value when the weight ratio increased from 10% to 15%. the thermal conductivity for polyester with orange peels was greater than the thermal conductivity of polyester with date seeds with maximum percentage occurred at weight ratio 10% is 14.4%, but the thermal conductivity of the industrial composite material was higher than the natural composite material. finally, the date seeds composite was a good insulator and it had a reduced heat transfer rate in comparison to the rest of the samples, also the maximum variation of temperature with time occurred in date seeds composite. keywords: natural material, polyester resin, weight ratio. 1. introduction two or more materials mixed homogenously at a microscopic scale defined as composite materials.one of its constituents is named as reinforcing phase and the other which is considered the base is named the matrix [1]. the main reason for using the natural materials in the reinforcement the composite materials is to decrease the cost and the pollution as well as these natural materials don’t cause any harm to the humans. in 2012, arumuga prabu and etal. [2] analyzed and studied the effect of adding the rec mud into banana fiber, sisal fiber reinforced polyester. it is concluded that this addition increase the mechanical properties of the composite. in 2013, mohammed razzaq[3], presented and studied the mechanical properties of three composites materials i.e (sunflowerpolyester), (water-melon-polyester) and (seed haydar abed dahad al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 1623 (2018) 17 shells-polyester) with different mixing ratio from (5wt% to 25wt%) and made a comparative between these composites. it was concluded from the results that the young modulus and hardness increase with increased the mixing ratio. in 2014 ishaya m. dagwa and josiah o. ohaeri[4], studied and investigated the mechanical and physical properties of hybrid composite materials consist of banana fiber-glass oil palm-polyester with different ratio. the results showed that the decreasing of flexural strength when the weight ratio of banana increased but increase the impact strength. the purpose of the present work was to study the effect of adding natural material (orange peels and date seeds) with particle size 98 μm to polyester resin on the mechanical and thermal properties compared with composite material made from industrial material (carbon and silica) with particle size 98 μm and polyester because the natural materials are cheap and not harmful to the people. the weight ratios are (5,10, and 15 wt. %) were studied, in experimental work, all samples were prepared manually and cutting by cnc machine. tensile tests, flexural tests, thermal conductivity test were performed to evaluate mechanical, thermal performances. 2. experimental work 2.1 materials processing in the present work, the composite which are hand lay-up for five kinds of composite material with three mass fraction (5%, 10%, 15%). the types of composite material that uses in this work is: pure polyester, orange peels particle with particle size 98 μm and unsaturated polyester, date seeds particle with particle size 98 μm and unsaturated polyester, silica particle with particle size 98 μm and unsaturated polyester, carbon particle with particle size 98 μm and unsaturated polyester. to fabricate the natural composite material there are several steps. first, collecting the material (date seeds, orange peels), second drying them by furnace for 30 minute at 60°c. third milled those by electrical mill machine, fourth the set of sieves were employed to get on date seeds and orange peels powder by the suitable size 98µm. finally, drying the powder of natural material for 30 minute at 60°c.the artificial material (silica and carbon particle) sieve to get the suitable particle size 98µm. rectangular flat panels were fabricated this materials using (290mm * 230 mm) glass open mold with four strip glass to be borders and adhesive by silicon. to avoid stick sheet paper put it on the glass plate the polyester (which has 1.05 g/���as density) is mixed with hardener together (hardener weight 0.02from polyester weight) and adding polyester. the weight of each particle and resin depends on the weight ratio of particle and resin, and they can be calculated from the following expressions weight of pure polyester w=ρm*vc ... (1) mf=w*ϑ … (2) mp=w*(1-ϑ) …(3) ϑ =weight ratio where: ρm: density of matrix (1.05 g/cm^3). mf, mp: weight of particle and polyester respectively. the weight measured by digital sensitive (libra sca301). when the samples manufactured, cutting it with cutting tool (cnc machine) shown in fig. 1 to make the tests. fig. 1. cutting tool cnc machine (rapimill700) 2.2 mechanical and thermal tests 2.2.1 tensile test test specimens were cut from the plates using cutting tool cnc machine, as depicted in figure (1). the dimensions of the tensile specimens was milled according to astm e 8m as shown in figure 2. all tensile tests were performed at room temperature and constant speed rate (1 mm/min) by a tinius olsen universal testing machine, which has a maximum capacity of (50 kn). the specimen’s tensile test is mounted vertically in a servo testing machine, and pulled with stroke control with large steel grips. tensile test done for five types of composite material and for three haydar abed dahad al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 1623 (2018) 18 different mass fraction (5%, 10%, 15%). the tensile specimen's before and after tensile test are shown in figure 4. fig. 2. section of tensile test specimen. fig. 3. tensile test machine according to astm e8m. all dimensions in millimeters. fig. 4. speciemens before and after tensile test. fig. 5. effect of weight ratio on young modulus (natural material). fig. 6. effect of weight ratio on ultimate stress (natural material). haydar abed dahad al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 1623 (2018) 19 fig. 7. effect of weight ratio on yield stress (natural material) fig. 8. effect of weight ratio on fracture stress (natural material) table 1, mechanical properties of natural and artificial composite material with mass fraction 5% and particle size 98µm composite material young's modulus (mpa) ultimate stress (mpa) yield stress (mpa) pure polyester 1375 20.6 1. 6 polyester +carbon 1125 31.2 2.3705 polyester+ silica 1705 39.75 3.879 polyester + date seeds 2084 44.24 4.306 polyester+ orange peels 1675 40.25 3.879 the results of tensile test that represented as (tensile strength, yield stress, and young modulus) are listed in table (1). in figure (5) should be noted that when the weight ratio for date seeds composite the increase from 10% to 15% the maximum young modulus decrease by 54%. and, the maximum for specimen that made from orange peel composite when the mass fraction increase from 10% to 15% the young modulus decrease by 40%. when the weight ratio for date seeds composite increase from 10% to 15% the maximum ultimate stress decrease by 34.3% , as shown in figure (6). also, it can be observe for specimen that made from orange peels composite that when the weight ratio increase from 10% to 15% the ultimate stress decrease by 31.6%. figure (7) shown that the maximum increasing in yield stress for date seeds composite occurs when the weight ratio changes 5%to 10% about three times and for orange peels composite when mass fraction change from 10%to15% with 46%. the maximum decreasing in fracture stress for date seeds composite occurs when the mass fraction changes10%to 15% with 34.2% and for orange peels composite when weight ratio change from 10%to15% with 30.7%, as noted in figure (8). when the weight ratio is 5% the maximum young modulus and ultimate stress occur in date seeds composite. but maximum yield stress occurs in date seeds composite. and the minimum young modulus occur in specimen made from carbon composite. the decreasing in strength is attributed to the poor interface between (natural composite) and (polyester). so the crack propagation occurred at this interface, the natural composite (orange peels, date seeds) in the unsaturated polyester matrix provides stress concentration, therefore providing sites for crack initiation, the larger mass fraction, the larger the stress concentration, along the naturally weak interface of the natural and polyester, and lowers tensile strength. 2.2.2 bending test flexural tests were performed according to astmd790 under a three-point bending. the tests were done using a servo-hydraulic testing machine, wdw-200 with speed of 5.0 mm/min. the results of the flexural tests are shown in figure 9 and table 2 the maximum improvement in the flexural strength was obtained at the orange peels ratio of 5 wt. % with has the maximum increasing percentage is 153.4% from pure polyester. from results of bending test could observe that orange peels composite material have the value of flexural strength greater than date seeds composite also could observe that the natural composite material give the good improvement than industrial composite material at weight ratio 5% because the natural of these materials increased the strength of the material reinforced. the flexural strength decrease when the loading ratio of natural composite increase this due to low degree of adhesion between the polymer and the natural haydar abed dahad al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 1623 (2018) 20 composite and the cross-link density was lowered at high mass friction contents because the distance between the polymers chain increase and natural particles prevent the contact between them, besides that in high percent of weight ratio the particles act as stress concentrators fig .9. flexural strength of natural composite material in various weight ratios. table 2, flexural strength of natural and artificial composite material with mass fraction 5% and particle size 98µm composite material flexural strength (mpa) pure polyester 5 polyester +carbon 6 polyester+ silica 6 polyester + date seeds 10.667 polyester+ orange peels 12.67 2.2.3 thermal conductivity test coefficient of thermal conductivity of all specimens was measured using hot disk thermal conductivity method [7]. very often composite materials results in anisotropic media and their thermal conductivity change along the axes because of the presences of reinforcing fibers embedded in the matrix. fig.10. represents the test apparatus (hot disk apparatus) and fig11 shows the principles of hot disk (two samples put in the device and change the temperature to same range and measure the temperature of the sample). the hot disk tps 500 thermal constants analyzer quickly and accurately measures thermal conductivity, thermal diffusivity and specific heat capacity of a wide range of materials. the economical tps 500 condenses the patented tps technology with next-generation analysis software, resulting in the smartest, and simplest-to-use thermal conductivity apparatus [8] . the tps 500 measures the thermal transport properties of solids, pastes, liquids and powders over a temperature range of -100 °c to 200 °c. the tps 500 encompasses similar accuracy and sample size flexibility as the benchmark tps 2500 s and workhorse tps 1500. in general, steady-state techniques are useful when the temperature of the material does not change with time. this makes the signal analysis straightforward (steady state implies constant signals). the disadvantage is that a well-engineered experimental setup is usually needed [9]. the transient techniques perform a measurement during the process of heating up. their advantage is quicker measurements. transient methods are usually carried out by needle probes. in this technique, the hot disk sensor (copper disk) serves as a heat source and a thermometer. during the measurement, the sensor is sandwiched between two halves of a sample and a constant current is supplied to the sensor. the temperature increase at the sensor surface is strongly dependent on the thermal transport properties of the surrounding material. by monitoring the temperature increase as a function of time, one can determine the thermal conductivity and thermal diffusivity of the surrounding material. [10] the results of temperature with time and thermal conductivity shown in figs [12, 13]. fig. 10. hot disk apparatus. fig.11.hot disk principles. haydar abed dahad al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 1623 (2018) 21 fig. 12. thermal conductivity coefficient results for natural composite material for different weight ratio. table3, thermal conductivity of natural and artificial composite material with weight ratio 5% and particle size 98µm composite material thermal conductivity w/m.k pure polyester 0.2101 polyester +carbon 0.2254 polyester+ silica ٠.2161 polyester + date seeds 0.2036 polyester+ orange peels 0.2159 fig. 13. variation of temperature with time from fig 12, it can be seen that the increasing of weight ratio of orange peels composite caused slightly increasing of thermal conductivity by 5% but when the weight ratio increase from 10% to 15% thermal conductivity decrease to the half value. from fig 12 can be note the increasing of adding material more than 10% caused decreasing in thermal conductivity, this decreasing attributed to the influence of additive, this is for both type but orange peels composite increased thermal conductivity more than date seed composite this mean that orange peel have influence on thermal conductivity than date seed. also can be seen that the thermal conductivity for orange peels composite is greater than thermal conductivity of date seeds composite the maximum percentage is at 10% mass fraction is 14.4% that mean the date seeds composite is good insulator for temperature. also can see from table3 that the material that has maximum thermal conductivity is carbon composite second silica composite third orange peels composite fourth pure polyester finally date seeds composite that mean adding date to pure polyester made it good insulator and it had a reduced heat transfer rate in comparison to the rest of the samples. from fig 13. can see the maximum variation of temperature with time occurs in date seeds composite because it is good isolator and the copper disk with is the source of temperature don't lose it temperature. 3. conclusion in this paper, the mechanical and thermal properties of natural (date seeds, orange peels) and haydar abed dahad al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 1623 (2018) 22 industrial (carbon and silica) composite materials at different weight ratios (5, 10, and 15wt. %) were investigated. according to the obtained results, the following conclusions can be drawn: 1regarding the mechanical properties, when the mass fraction for the date seeds composite increased from 10% to 15%wt, the maximum young's modulus decreased by 54%, the maximum ultimate tensile stress decreased by 34.3% and the maximum fracture stress decreased by 34.2% when the mass fraction is 5%, the maximum young’s modulus, yield stress and ultimate tensile stress occurred in date seeds composite. the results of the flexural tests showed that the maximum improvement in the flexural strength was obtained at the orange peels ratio of 5 wt. % with a maximum increasing percentage of 153.4% than pure polyester. from result of tensile and flexural tests, the natural composite material has strength more than industrial material 2referring to the thermal properties, the value of thermal conductivity for the natural composite material with orange peels increased by 5% when the mass fraction increased from 5% to 10%, but when this ratio increased from 10% to 15%, it decreased to the half value. also, the thermal conductivity for the orange peels composite is greater than that for the date seeds composite, and the maximum percentage is 14.4% at 10% weight ratio. this means the date seeds composite is a good insulator for temperature, but the industrial composite material has a higher thermal conductivity than the natural composite material. finally, the addition of date seeds made the pure polyester become a good insulator and it had a reduced heat transfer rate in comparison to the rest of the samples, also the maximum variation of temperature with time occurred in the date seeds composite because it is a good isolator. 4. references [1] reddy j.n. “mechanics of laminated composite plates and shells: theory and analysis “. 2ed; crc press 2004. [2] arumuga prabu v., manikandan v., uthayakumar m., kalirasu s., "investigations on the mechanical properties of red mud filled sisal and banana fiber reinforced polyester composites", materials physics and mechanics 15 (2012) 173-179 received: november 1, 2012. [3] mohammed razzaq mohammed, '' study of some mechanical properties of unsaturated polyester filled with the seed shells of sunflower and water-melon'', journal of babylon university/engineering sciences/ no. (4)/ vol. (21): 2013. [4] ishaya m. dagwa,josiah o. ohaeri , " property evaluation of hybrid opebf/banana/glass fiber reinforced unsaturated polyester composites'' american journal of materials science and engineering, 2014, vol. 2, no. 4, 45-53. [5] rafah a. nassif "effect of chemical treatment on the some electrical and thermal properties for unsaturated polyester composites using banana fibers" eng.& tech. journal, vol.28, no.10, 2010. [6] k. srinivasulu reddy and d. sreedhar, "thermal conductivity of natural fiber, glass fiber & cnts reinforced epoxy composites" international journal of current engineering and technology e-issn 2277 – 4106, p-issn 2347 – 5161. 2016. [7] dr. sanaa a. a. hafad, " studying some of mechanical properties (sawdust/unsaturated polyester) composite in salt solution'', eng. & tech. journal, vol. 28, no. 16, 2010. [8] m. davallo, h. pasdar, m. mohseni, " mechanical properties of unsaturated polyester resin", international journal of chemtech research, coden (usa): ijcrgg issn: 0974-4290, vol.2, no.4, pp 2113-2117, octdec 2010. [9] y. he, intel corporation; g.s. ng, massachusetts institute of technology and intel corporation, "hot disk: a transient plane source technique for rapid thermal conductivity measurement". [10] c. buratti, e. belloni email author ,l. lunghi ,m. barbanera " thermal conductivity measurements by means of a new ‘small hot-box’ apparatus: manufacturing, calibration and preliminary experimental tests on different materials", international journal of thermophysics, 22 february 2016, doi: 10.1007/s10765-0162052-2 )2018( 1623، صفحة 4د، العد14دجلة الخوارزمي الهندسية المجلم حيدر عبد ضهد 23 ربون دراسة تاثير اضافة المواد الطبيعية (نوى التمر وقشور البرتقال) والصناعية (الكا الميكانيكية والحرارية للمواد المركبة البولمريةوالسليكا) على الخواص حيدر عبد ضهد* سامح فريد حسن** علي حسين علوان*** *،**قسم الهندسة الميكانيكية/ الجامعة التكنولوجية *دائرة البحث والتطوير/ وزارة العلوم والتكنولوجيا hayder_abed2002@yahoo.com :البريد االلكتروني* sameh_fareed@ymail.com:البريد االلكتروني** eng.ali83@yahoo.com :البريد االلكتروني*** الخالصة قشر البرتقال (ية تم دراسة الخصائص الميكانيكية والحرارية للمواد المركبة التي تتكون من بولي استر غير مشبع المقواة بأنواع مختلفة من المواد الطبيع وقد تم اضافة . %١٥و ١٠%و ٥%تم اخذ قيم متلفة من النسب الوزنية، . ميكرون ٩٨مع حجم حبيبي ) الكربون والسيليكا(والمواد الصناعية ) ونوى التمر والصناعية وقد تم أجراء اختبارات الشد و االنحناء والتوصيل الحراري للبولي استر والمواد المركبة الطبيعية. مواد صناعية ومواد طبيعية الى البولي استر ٪، انخفض معامل ١٥٪ إلى ١٠وأظهرت النتائج أنه عندما زادت نسبة الوزن للبوليستر مع نوى التمر من . لتحديد تأثير النسبة الوزنية على خصائص المواد وأظهرت نتائج اختبارات . هاد الكسر٪ الحد األقصى لمعامل المرونة واإلجهاد الخضوع واإلج٥عندما تكون النسبة الوزنية لنوى التمر. ٪٥٤المرونة بنسبة في حين أظهرت نتائج اختبارات االنحناء أن الحد األقصى من التحسن في قوة . الشد وااالنحناء أن المواد المركبة الطبيعية لها قوة أعلى من المادة الصناعية وانخفضت الموصلية الحرارية .٪ بالمقارنة مع البوليستر النقي١٥٣٫٤٪ ، حيث الحد األقصى لزيادة هي ٥االنحناء يتم الحصول عليه لقشور البرتقال بنسبة الموصلية الحرارية للبوليستر مع قشور البرتقال أكبر من الموصلية . ٪١٥٪ إلى ١٠من قشور البرتقال إلى قيمة النصف عندما زادت النسبة الوزنية من ولكن التوصيل الحراري للمواد المركبة الصناعية ٪ ١٤٫٤٪ هي ١٠وكانت النسبة المئوية القصوى عند النسبة الوزنية . الحرارية من البوليستر مع نوى التمر وأخيرا، فإن المركب نوى التمر هو عازل جيد وله معدل نقل حراري منخفض بالمقارنة مع بقية العينات، وكذلك االختالف . اعلى من المواد المركبة الطبيعية .رجات الحرارة مع مرور الوقت في مركب نوى التمراألقصى لد al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 8, no. 1, pp11 -17 (2012) design a fault tolerance for real time distributed system ban m. khammas department of network engineering/college of information engineering/ university of al-nahrain email:ban_moh79@yahoo.com (received 7 march 2011; accepted 23 october 2011) abstract this paper designed a fault tolerance for soft real time distributed system (ftrtds). this system is designed to be independently on specific mechanisms and facilities of the underlying real time distributed system. it is designed to be distributed on all the computers in the distributed system and controlled by a central unit. besides gathering information about a target program spontaneously, it provides information about the target operating system and the target hardware in order to diagnose the fault before occurring, so it can handle the situation before it comes on. and it provides a distributed system with the reactive capability of reconfiguring and reinitializing after the occurrence of a failure. keywords: soft real time, distributed system, fault tolerance. 1. introduction distributed systems have made substantial progress over the recent years in terms of functionality, scalability performance and openness so that they are an alternative even for very demanding and complex control systems. this makes the developer of a functional and dependable system face enormous challenges largely because of loosely coupled hardware architecture with no physical shared memory, many things that straightforward in centralized systems are difficult in distributed systems. for example, synchronization processes with spread threads of control typically use shared variables on a single machine, but must do with message passing in a distributed system. the extra time delay associated with sending messages over a network increases the asynchrony of the processes and necessitates the use of special protocols to coordinate their respective actions [1]. a distributed real-time system (drts) is a distributed system whose correctness depends on meeting timing constraints as well as logical requirements. using distributed computing to exploit the inherent concurrency of real-time systems leads to distributed real-time systems. for example, for a real-time system that can meet all deadlines with five processes, a distributed processing may be a solution. in this example one processor can be used to handle two periodic processes while the other processor handles the five periodic processes. it can be seen that the distributed system can be introduced to improve a real-time system‟s response time and/or reliability. by decomposing a large real-time application into a set of processes, the decomposed processes can operate concurrently using interprocess communication and synchronization. thus the response time can be improved with parallel processing. reliability can be increased with distributed systems. this is important because real-time systems are expected to operate continuously with extremely high reliability even with the presence of a faulty processor. fault tolerance can be achieved by detecting a faulty processor, saving and restoring the computational tasks of the faulty processor, and then distributing the recovered tasks to the remaining processors so that the drts can continue to operate, although with degradation of computing power. the increase the reliability of the system offers the availability by using duplicate software and ban m. khammas al-khwarizmi engineering journal, vol. 8, no. 1, pp 11 -17 (2012) 12 backup computers and self-checking technique. for high availability and integrity, the replicas need to be diverse, so failures are sufficiently independent. for high performance, a sufficient number of replicas is needed in order to meet the load imposed on the replicated object [1]. reliability and availability are essential characteristics for computer systems operation. a runtime monitoring system contributes for improving reliability and availability, respectively, by continuous failure detection and by reducing time to diagnose failures. in most systems, the savings in ground support and maintenance costs offset the initial cost of hardware and software monitoring system in a year [2]. savings in ground support costs are achieved by reducing manual diagnostic costs. the run-time monitoring system will automatically identify failures as they happen in normal operation. thus, support personnel spends less time and money in troubleshooting failures. this also results in reduced turn-around times and improved system availability [3]. 2. related work researches in this filed made substantial progress over the recent years in terms of functionality, scalability performance and openness. failure detectors are important building blocks for constructing fault-tolerant distributed systems. in [4] it takes a view of fault tolerance of real time computing and its attributes in automatic computing. and [5] discusses progress in the field of real-time fault tolerance in different way. in particular, it considers synchronous vs. asynchronous fault tolerance designs, maintaining replica consistency, alternative fault tolerance strategies, including checkpoint restoration, transactions, and consistent replay, and custom vs. generic fault tolerance. in [6] it shows a simple algorithm and easy to implement. it also increases utilization speed and efficiency of scheduling. it can also be concluded that appropriate use of redundancy is important since too much redundancy increases reliability but potentially decreases the schedule ability. too little redundancy decreases reliability but increases schedule ability. also, designing, managing redundancy incurs additional cost, time, and memory and power consumption. thus this algorithm can be efficiently used for fault tolerance in case where multiprocessors are used to run realtime applications. in [7] it proposes a reliability monitoring scheme for active fault tolerant control systems using a stochastic modeling method. the reliability index is defined basically on system dynamical responses and a safety region; the plant and controller are assumed to have a multiple regime model structure, and a semi-markov model is built for reliability evaluation based on the safety behavior of each regime model estimated by using monte carlo simulation. moreover, the history data of fault detection and isolation decisions is used to update its transition characteristics and reliability model. this method provides an up-todate reliability index as demonstrated on an aircraft model. in thesis [8], it deals with techniques for tolerating effects of transient and intermittent faults. re execution, software replication, and rollback recovery with check pointing are used to provide the required level of fault tolerance at the software level. hardening is used to increase the reliability of hardware components. these techniques are considered in the context of distributed real-time systems with static and quasistatic scheduling. 3. the architecture of the proposal system this research is done in special environment chosen to implement and test the work. it is programmed in visual c++ (mfc) language, the computers are connected by ethernet network with 100 mbps speed and the topology is star connection. the (ftrtds) has a distributed unit and a central unit. the distributed fault tolerance unit (dftu) is distributed on all computers in the system and it is run with system boot of that computer as it will be explained in 3.1, and central fault tolerance unit (cftu) which it is run manually by users (or by rtds administrator) in one computer chosen for. it needs backup software for each part of distributed system, to use it when it necessary, as it will be explained later. 3.1. distributed fault tolerance unit (dftu) to give the cftu full capability to diagnosis and control all faults on all computers in a network, there must be a program work as a service to it on each network‟s computer. this program is called dftu. its jobs are monitors the software and hardware of distributed system and diagnoses the error and tries to correct it before any fault occurred. and send a message to inform ban m. khammas al-khwarizmi engineering journal, vol. 8, no. 1, pp 11 -17 (2012) 13 the cftu if the fault or error is done successfully or not. the dftu is run in each computer automatically with computer system startup as a service. the term “service” in windows nt or windows xp is used to denote both a special kind of win32 process and windows nt kernel-mode device drivers. in fact, a component of the operating system known as the “service controller” (or “service control manager”, or scm) is used to load and control both types of services. in that context, a service is more or less a program that gets executed by nt (as opposed to getting directly executed by a user) and that responds to special requests to start, pause, or stop execution. services have some special capabilities beyond those of the typical win32 process. for one thing, you can tell nt to start your service when the system loads, before any users have logged on. that makes services a good choice for software that needs to start automatically and run constantly in the background, whenever the system is up [9]. 3.2. central fault tolerance unit (cftu) cftu is run on one computer chosen by the administrator. its jobs are monitoring the dftu work, showing the state of rtds and handling the fault that dftu cannot handle. it has several functions to do its job. the first one is called connection function which has two steps. the first step is called „identification step‟. its job is identifying each computer available in the network. in this phase, the cftu make a connectionless service with all computers using mailslot technique which is a connectionless technique. mailslots are a simple way for a process to broadcast messages to multiple processes. one important consideration is mailslots broadcast messages using datagram. a datagram is a small packet of information that the network sends along the wire. like a radio or television broadcast, a datagram offers no confirmation of receipt; there is no way to guarantee that a datagram has been received [9]. because of that the cftu repeat this step twice to insure that all the computers in its network send their names. at the end of this step computer‟s names and numbers are being collected; then the second step begins. the second step is called „connection step' the named pipes will be used instead of mailslots for interprocess communications. named pipes are a simple way for two processes to exchange messages. they are like telephone calls: you talk only to one party, but you know that the message is being received. this type of connection will be used to increase the reliability of the systems because named pipe is an example of connection-oriented communications, the transmission of the data in this type is across a path that stays established until one of the nodes drops the connection. this type of logical connection guarantees that all blocks of data will be delivered reliably. while mailslots are an example of a connectionless communications, the transmission of the data in this type is across a network in which each packet is individually routed to its destination, based on information contained in the packet header. the path the data takes is generally unknown because there is no established connection between the computers that are communicating. connectionless services can drop packets or deliver them out of sequence if each of the packets gets routed differently [10]. in this step, it uses the computer's names collected from first step to connect with each other by named pipes connection. two pipes will be opened with each computer; one for sending and one for receiving to increase the speed. a thread will be created for each connection because the use of the single thread limits cftu responsiveness. the reason for that limitation of responsiveness is that only one dftu can be served at a time, even though the cftu may be idle while waiting for the child process to complete. for example, the dftu (client) must open a connection to the dftu (server), send a request, wait for a response, and terminate the connection. other dftu (clients) cannot connect during this time. thread can turn on this synchronously with concurrent dftu (server) processing, long-lived client/server connections, and higher availability for client requests. 4. the whole demonstration of the proposal fault tolerance system work before the rtds's module is run, some information is needed to be known by cftu, like their names, location, priority and so on. they are stored, by administrator before the run step, in a special file, called information file. as mentioned in 3.1, the dftu runs automatically in each computer in the distributed system platform but the cftu is run manually by the administrator and fill the information about the ban m. khammas al-khwarizmi engineering journal, vol. 8, no. 1, pp 11 -17 (2012) 14 system just for the first time it is run, i.e. not for each run the file information must be filled, but it can be updated. when the cftu is run the connection function begin first to connect the cftu with each dftu in the whole distributed system as described in 3.2 see algorithms (1, 2 and 3). then create a new thread for collection function whose job is collecting the hardware information about the whole distributed system, like memory space, hard disk space and processor information. the collection function must run in a thread because it need to keep running when the rtds run to collect the changing information about the system when it is running. algorithm (1) dftu read and write functions. 1. mailsloat connection 2. if (success) 3. send computer name 4. else 5. go step 1 6. end if 7. create a thread for read connection 8. while() 9. connect named pipe with cftu for read 10. if (fail) 11. error_no=get last error() 12. call error handle (error_no) 13. go to step 9 14. end if 15. call connect write pipe function 16. wait for any message from cftu 17. enter critical section //to not be interjection // by another thread 18. if (connection cut off) 19. call error handle (error_no) 20. leave critical section 21. go to step 9 22. end if 23. execute the message 24. leave critical section 25. go to step 16 26. end while connect write pipe function () 1. connect named pipe with cftu for write 2. if (fail) 3. error_no=get the error 4. call error handle (error_no) 5. go to step 2 6. end if 1. create monitoring thread for each process 2. if (process fail) 3. call error handle (error_no) 4. save the error and the time 5. if the same error repeat for 3 times in small period 6. write to cftu to handle this error 7. end if algorithm (2) dftu distributed process monitoring function. algorithm (3) cftu connection function . 1. mailsloat connection 2. if (success) 3. read(computernames, computerno) 4. else 5. error message a. if (continue) 6. go step 1 7. else 8. end the program 9. end if 10. end if 11. for (1 to computerno) 12. create a thread for read connection 13. create a thread for write connection 14. end for --------inside read thread---------------- 1. while() 2. connect named pipe with dftu for read 3. if (fail) 4. error_no=get last error() 5. call error handle (error_no) 6. go to step 2 7. end if 8. wait for any message from dftu 9. enter critical section //to not be interjection by another thread 10. if (connection cut off) 11. error_no=get last error() 12. call error handle (error_no) 13. leave critical section 14. go to step 9 15. end if 16. execute the message 17. leave critical section 18. go to step 8 19. end while --------inside write thread---------------- 1. while() 2. connect named pipe with dftu for write 3. if (fail) 4. error_no=get last error() 5. call error handle (error_no) 6. go to step 2 7. end if 8. end while ban m. khammas al-khwarizmi engineering journal, vol. 8, no. 1, pp 11 -17 (2012) 15 when rtds begins running, the dftu creates a thread for each module that runs in its computer for monitoring function. its job is monitoring that module job and is used from collection function information to tolerate the error before the fault occurs if possible and if not, it try to tolerate the fault by a different thing depending on the collection function information, like if module fail, it try to reload it again if there is no problem in this computer. but if the reload fail again or there is a problem in this computer, like there is no memory space, it informs the cftu. the cftu tries to reload it on another computer in that distributed system, (see figure 1). fig.1. monitoring function . the cftu takes a handle of any bad situation, when the dftu fails to control that bad situation, like computer breakout. in this situation cftu decides to run the modules that were running in that broken computer in another suitable computer depends on the previous collection information. 5. backup cftu service after the cftu creates monitoring thread it calls the backup service function. it chooses one dftu depending on file information (filled by the administrator as mentioned in section 4) and declares it as cftu recovery (cftur). it takes an action when cftu is damaged. when cftu is damaged, all the dftu detects that because the pipes are broken. only the one which is chosen by backup service function will take a handle of that situation. when the cftur detects cftu damage, it tries to reload it from its computer taking in consideration the last state, till it handles the error. see algorithm 4. if the connection failed (i.e the computer is damaged or wire break, ect) it take no farther action till the administrator repairs the damage. 6. conclusions the diagnosis capabilities of the system should be tailored to the needs of different users and applications. this can be achieved through a variation of the diagnosis techniques used to construct the results of reasoning. 1. reload the backup cftu on the cftur //to handle the situation till we cane reload it in the same computer 2. if (error_no == database lose) // i.e the software destroy 3. connect named pipe with dftu of the same cftu for read 4. if connection (success) 5. connect named pipe with dftu of the same cftu for write 6. reload cftu on its origin computer 7. destroy the backup cftu 8. end if algorithm (4) cftur repair function one of the rtda processors runs dftu create a monitoring thread it tries to overcome the error if error shown before the fail happened if the process failed tries to re-run it again if it failed to re-run it sends a message to cftu to handle this situation end yes yes yes wait no no no ban m. khammas al-khwarizmi engineering journal, vol. 8, no. 1, pp 11 -17 (2012) 16 this proposal design decrease the response time by using of hybrid technique of fault tolerance between distributed and central techniques led to increase the performance of the plant because of increase the speed of diagnosis the problem and handle it. it increases the reliability of the system by offering the availability by using duplicate software and backup computers. it is easier to re-use in new circumstances than a conventional program because of using the diagnostic systems employing functional reasoning which is more adaptable. given the soaring costs of software production it may be that the economics of software ownership. for example, if it is required to modify an existing system for diagnosis of similar plant, only a need to update the data base that contains the structural description of the system is needed, when the set of components is the same for both the old and the new systems. when the two systems have many structured similarities, the modification becomes even simpler. hence, diagnostic systems employing functional reasoning are very flexible and adaptable. it decreases the number of failure by monitoring the whole system (software and hardware). this let the cftu augury of the bad situation. so it takes handle before the failure occurs. 3. references [1] b. charron-bost, f. pedone, and a. schiper (eds.), "replication", lncs 5959, pp. 19– 40, 2010. c_springer-verlag berlin heidelberg 2010. [2] andrew s. tanenbaum, “distributed operating systems”, prentice-hall, 2010. [3] sérgio ricardo rota and jorge rady de almeida jr.,"run-time monitoring for dependable systems: an approach and a case study", proceedings of the 23rd ieee international symposium on reliable distributed systems 2004. [4] paul ezhilchelvan, "on the progress in fault-tolerant real-time computing", proceedings of the 23rd ieee international symposium on reliable distributed systems 2004. [5] p.m. melliar-smith and l.e. moser, "progress in real-time fault tolerance", proceedings of the 23rd ieee international symposium on reliable distributed systems 2004. [6] a. ch risty persya and t.r. gopalakrishnan nair, " fault tolerant real time systems", international conference on managing next generation software application (mngsa08), coimbatore,2008. [7] hongbin li, qing zhao and zhenyu yang, "reliability monitoring of fault tolerant control systems with demonstration on an aircraft model", journal of control science and engineering, vol. 2008, article id 265189, pages 135-145. [8] viacheslav izosimov, "scheduling and optimization of fault-tolerant distributed embedded systems", linköping university, department of computer and information science, sweden, 2009. [9] editors of windows developer‟s journal, “windows nt programming in practice”, miller freeman, 1997. [10] microsoft developer network (msdn) library, april 2001. 2012) )11 17 ، صفحة 1، العذد8 هجلة الخوارزهي الهنذسية الوجلذ باى هحوذ خواس 17 تصوين هصحح األخطاء لنظام حقيقي هوزع باى هحوذ خواس جاهؼت الٌهرٌي/ كلٍت هٌذست الوؼلىهاث/ قسن هٌذست الشبكاث ban_moh79@yahoo.com : االلكتروًًالبرٌذ الخالصة هزا الٌظام هظون لٍكىى غٍر هؼتوذ ػلى اَلٍت الخاطت والخىاص للٌظام الذقٍقً الورى . هزا البذج طون هظذخ أخطاء لٌظام دقٍقً هرى هىزع . هزا الوقترح هظون لٍكىى هىزع ػلى كل داسبت هي الٌظام وهسٍطر ػلٍه هي قبل ودذة هركسٌت. الوىزع الزي ٌؼول هؼه هى ٌجهس بوؼلىهاث ػي ًظام التشغٍل واألجساء الظلبت الوستخذهت هوا ٌوكي هي تشخٍض األخطاء قبل ، الضافت لجوغ الوؼلىهاث آًٍا ػي الٌظاماوب . وٌسود الٌظام الوىزع بالقابلٍِت التفاػلٍِت إلػادة التَشكٍل وإػادة التَْشغٍل بؼذ دذوِث فشل. فٍتن أتخار الالزم،وقىػها mailto:ban_moh79@yahoo.com������ mailto:ban_moh79@yahoo.com������ اميل وزياد ومهى al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 8, no. 4, pp 106-117 (2012) dehydration of ethanol using pervaporation separation with nanoporous hydrophilic silica ceramic membrane ameel mohammed rahman al-mayah* zyad rafaa zair** maha hadi al-hassani*** *,** department of biochemical engineering /al-khwarizmi college of engineering/university of baghdad *** department of chemical engineering /college of engineering/university of baghdad (received 31 january 2012; accepted 30 december 2012) **zydzair@yahoo.co.uk abstract the pervaporation using a commercial hydrophilic ceramic membrane supplied from pervatech was conducted. the dehydration of ethanol/ water system was used as a model for the pervaporation study. pervaporation experiments of ethanol/water system were carried out in the temperature range of 303-343k, ethanol concentration in the feed 10-90 vol. % and the feed flow rate in the range of 0.5-10 l/min. in this work, the effect of operation parameters on permeates fluxes as well as permeates separation factors have been studied. the water flux is strongly dependent on the temperature; it increased with increasing in temperature, which in turn decreased the selectivity of membrane to water molecules. in addition water flux was decreased with increasing of ethanol concentration and increased with increasing feed flow rate. the optimal operational conditions of pervaporation process are: t=333 k, feed flow rate 6 l/min, and 90 vol.% ethanol concentration in the feed. high values of water flux and separation factor were obtained. the final results agreed well with other studies reported in the literature. keywords: pervaporation, ethanol dehydration, bioethanol, hydrophilic ceramic membrane, silica. 1. introduction the increase concern for negative impact of gaseous emissions from fossil fuel on the environmental as well as needs for alternative fuels has put great pressure on our society to find renewable friendly fuel alternatives. one of the most common renewable biofuel is bioethanol which is the dominated biofuel in the global energy market and produced from biomass by fermentation [1-3]. in bioethanol fermentation process, one of the major challenges associated with biofuel development and application is the availability of efficient separation and purification technique, which typically accounts for at least 40% (up to 80%) of the total process cost [1]. ethanol/ dehydration is a cost effective task due to the formation of ethanol/water azeotrope. separation azeotropic mixtures by conventional methods are expensive and consume large energy. among these numerous separation methods, ethanol dehydration by pervaporation is the most widely used and promising technology. pervaporation technology and their applications in the industrial separation processes has been grown considerably during the last three decades, and during the last few years becomes the most exciting aspects of separation [3-9]. pervaporation is energy save, environmental, high selectivity and low operational cost method of separating close boiling point mixtures consists of heat sensitive compounds. in pervaporation process, the dehydration is achieved by permselective membrane. water molecules pass the membrane (water-permselective membrane) whereas the impermeable molecules refluxed to the system. the permselective membrane materials play an essential role in dehydration process. pervaporation dehydration performance mailto:zydzair@yahoo.co.uk ameel mohammed rahman al-khwarizmi engineering journal, vol. 8, no.4, pp106-117 (2012) 107 can be improved by adjusting the hydrophilic and hydrophobic properties of a membrane material [5]. there are two types of pervaporation membranes used for ethanol/water mixture, the water permselective and ethanol-permselective membranes [7]. the mechanism of transport through the permselective membrane is solutiondiffusion mechanism and it considered to be three step process consisting of: (i) sorption of the permeants at the liquid upstream side of the membrane, (ii) diffusion of the permeants through the membrane and (iii) desorption at the lowpressure side of the membrane. therefore, the permeation rate is a function of solubility and diffusivity. in fact, the membrane selectivity is affected by both solubility, which is a thermodynamic property and diffusivity, which is a kinetic property [10]. a good pervaporation membrane material should have high permeation flux and separation factor for the pervaporation dehydration of alcohol. polymeric and inorganic membranes are highly selective and permeable have been reported for dehydration of ethanol/ water systems [11]. silica membranes are class of inorganic membranes. silica or silicabased membranes are highly selective to permeation of smaller molecules and are relatively inexpensive and quite stable in acidic solutions [12]. the present study aimed to evaluate the performance of prevatch hybsi commercial ceramic silica membrane for dehydration of ethanol by pervaporation. ethanol/water binary system separation is a well known system and therefore it was chosen as the model for this study. the effect of operating parameters (feed flow rate, ethanol concentration in the feed and operating temperature) on the membrane permeate fluxes and separation factors were explored in laboratory scale pervaporation unit which was developed locally. the thermodynamic properties were also discussed. finally, the final results were also compared with the other reported researches present in the literature. 2. experimental work 2.1. materials ethanol of analytical grade (obtained from sigma-aldrich company) and deionized water were used in the preparation of ethanol/water mixtures for pervaporation experiments. 2.2. membrane commercial hydrophilic silica membrane supplied by pervatech bv (the netherlands) was used. the membrane is available in the form of cylindrical tube consisted of an α-alumina support tube, with 7 mm internal diameter and 50 cm length , and a γ-alumina intermediate layer on the internal face of the tube. the silica layer was placed on top of the intermediate layer. the active area per tube is 0.01 m2. this membrane is essentially a dehydration membrane and is used for removal of water from feed streams. 2.3. pervaporation unit pervaporation experiments with the ceramic membrane were performed on a laboratory scale pervaporation unit. the unit was developed locally and the schematic of the pervaporation experimental setup is shown in fig. 1. the unit is designed so that the pervaporation experiments can be performed on the cylindrical tube membrane. this unit is consist of booster feed pump (magnetic drive), feed flask of 1 l (glass type), vapour condenser, heating mantel of 1l size, pervaporation module, pressure gage, vacuum pressure gage, flow meter, two vapour traps and vacuum pump. the membrane unit is a tubular, lab scale module had to be designed locally to conduct pervaporation experiments on the ceramic membrane. the schematic of this module is like the form of a double pipe heat exchanger; the hybsi ceramic membrane forms the inner pipe and the outer shell is made up of a stainless steel pipe. the feed is circulated on the inner side of the membrane tube whereas the permeate is drawn from the annual side of the module. ameel mohammed rahman al-khwarizmi engineering journal, vol. 8, no.4, pp106-117 (2012) 108 fig. 1. schematic diagram of a laboratory scale pervaporation unit. 2.4. pervaporation experiments pervaporation experiments were conducted in a batch way. 10, 30, 60 and 90 vol. % of alcoholwater systems were used over a broad range of operating conditions. experiments were carried out in the temperature range of 30-70°c, feed flow rate of 0.5-10 l/min, whereas the vacuum permeate pressure was kept nearly constant at 10 mbar. during the experimental work, liquid nitrogen was used as a cooling medium in the permeate trap in order to condensate the permeated vapour. an additional trap has been used in the unit for safety purposes. the feed pressure was kept constant at 3.5 bar. it was circulated at a pre-specified flow rate, from a feed tank through the inside of the ceramic membrane tube; also the feed is continuously recycled back to the feed tank. the outside of the ceramic membrane tube was evacuated by using vacuum pump. the stainless steel membrane module was heated with tab heater. the feed in the tank was heated to about 5°c higher than the membrane surface. the permeate was condensed in a cold traps. in all experiments, the weights of the collected permeate (with ceramic membrane) was less than 1% of the weight of the feed charged to the tank. this means that the feed composition remains constant during the duration of the experiment. the samples were taken from the unit at the end of every 20 min time intervals from the feed and permeate to determine the partial, total fluxes and separation factors. the total flux j and separation factor (α) were calculated from the following equations [13]: ta qj . = ...(1) ameel mohammed rahman al-khwarizmi engineering journal, vol. 8, no.4, pp106-117 (2012) 109 where q(g) is the total mass of permeate collected in t hours, and a(m2) denoted the effective area of the membrane [14]. ba ba yx xy . . =α ...(2) where xa and xb represent the ethanol and water concentration (wt.%) in the feed solution respectively, ya and yb represent the ethanol and water concentrations (wt.%) in the permeate. the sorption capacity was (sc) defined as [15]: d ds w wwsc − = ...(3) where wd and ws are the weight of the dry and swollen membrane samples, respectively. 2.5. pervaporation experimental analysis the collected feed and permeate pervaporation samples were analyzed to determine the composition. the analysis were performed using a gas chromatography (gc) measurement (shimatzu 2010a). 3. results and discussion 3.1. effect of feed concentration on membrane performance the effect of feed concentration on the membrane performance at different temperatures is shown in figs. 2 4. in the whole range of ethanol concentration (10-90vol. %), it can be observed that ethanol flux increased with increasing of ethanol concentration while water and the total fluxes decreased. this can be attributed to the fact that the decreasing in water flux might be related to the presence of the association equilibrium between water and ethanol molecules. at low ethanol concentrations, water molecules are in excess of ethanol molecules, it can be expected that water molecules would still be predominantly present in the form of isolated water molecules. therefore, the permeation of water is less influenced by the presence of association equilibrium. at higher concentrations, however, ethanol molecules are in excess of water molecules. the decreasing in the concentration of isolated water molecule might be responsible for decreasing of water flux. the effect of feed concentration on separation factors can be observed in figs. 5 and 6. ethanol separation factor decreased with increasing of ethanol concentration in the feed, while water separation factor increased over the same range of ethanol concentration. the decreasing of ethanol concentration facilitates water sorption on the surface of the membrane and, in turn, increases the swelling of the membrane, which enhances water molecules permeation. moreover, water molecules smaller than ethanol and this increases the diffusion rate of water which in turn decreases the separation factor of water at low ethanol concentration and increases the separation factor of ethanol and vice versa. the same observations were reported by other studies [1, 2, 16-20]. 0 20 40 60 80 100 120 140 0 10 20 30 40 50 60 70 80 90 100 ethanol concentration in the feed, (vol.%) e th an ol fl ux , ( g/ m 2 .h ) t= 303k t= 318k t= 333k t= 343k fig. 2. effect of ethanol concentration in the feed on ethanol flux at different temperatures. 700 725 750 775 800 825 850 875 900 0 10 20 30 40 50 60 70 80 90 100 ethanol concentration in the feed, (vol.%) w at er fl ux , ( g/ m 2 .h ) t= 303k t= 318k t= 333k t= 343k fig. 3. effect of ethanol concentration in the feed on water flux at different temperatures. ameel mohammed rahman al-khwarizmi engineering journal, vol. 8, no.4, pp106-117 (2012) 110 850 860 870 880 890 900 0 10 20 30 40 50 60 70 80 90 100 ethanol concentration in the feed, (vol.%) to ta l f lu x, (g /m 2 .h ) t= 303k t= 318k t= 333k t= 343k fig. 4. effect of ethanol concentration in the feed on total flux at different temperatures. 0 0.2 0.4 0.6 0.8 1 1.2 0 10 20 30 40 50 60 70 80 90 100 ethanol concentration in the feed, (vol.%) et ha no l s ep ar at io n fa ct or , ( -) t= 303k t= 318k t= 333k t= 343k fig. 5. effect of ethanol concentration in the feed on ethanol separation factor at different temperatures. 0 10 20 30 40 50 60 70 80 0 10 20 30 40 50 60 70 80 90 100 ethanol concentration in the feed, (vol.%) w at er s ep ar at io n fa ct or , ( -) t= 303k t= 318k t= 333k t= 343k fig. 6. effect of ethanol concentration in the feed on water separation factor at different temperatures. 3.2. effect of temperature on membrane performance the effect of pervaporation operating temperature on normalized ethanol and water fluxes and separation factors are shown in figs. 7 11. water and the total fluxes increased with increasing of temperature, while ethanol flux decreased over the same range of temperature. when the temperature increases, the membrane swells leading to an enlarge permeation flux and have more free volume and chain mobility as well as the vapour pressure difference is higher, which enhance the transport driving force. these two factors favor the diffusion of ethanol and water molecules through the membrane, leading to higher permeate flux. however, since water molecule is smaller than that for ethanol, the diffusion rate of water is faster, decreases the separation factor. this is agreed well with other studies reported in the literature [3, 10, 17-25]. ameel mohammed rahman al-khwarizmi engineering journal, vol. 8, no.4, pp106-117 (2012) 111 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 300 305 310 315 320 325 330 335 340 345 350 temperature, (k) et ha no l f lu x, () 10 vol. % 30 vol. % 60 vol. % 90 vol. % fig. 7. effect of temperature on ethanol flux at different feed concentration. 700 725 750 775 800 825 850 875 900 300 305 310 315 320 325 330 335 340 345 350 temperature, (k) w at er fl ux , ( -) 10 vol. % 30 vol. % 60 vol. % 90 vol. % fig. 8. effect of temperature on water flux at different feed concentration. 850 855 860 865 870 875 880 885 890 895 900 300 305 310 315 320 325 330 335 340 345 350 temperature, (k) to ta l f lu x, () 10 vol. % 30 vol. % 60 vol. % 90 vol. % fig. 9. effect of temperature on the total flux at different feed concentration. 0 0.2 0.4 0.6 0.8 1 1.2 300 305 310 315 320 325 330 335 340 345 350 temperature, (k) et ha no l s ep ar at io n fa ct or , ( -) 10 vol. % 30 vol. % 60 vol. % 90 vol. % fig. 10. effect of temperature on ethanol separation factor at feed concentration. ameel mohammed rahman al-khwarizmi engineering journal, vol. 8, no.4, pp106-117 (2012) 112 0 10 20 30 40 50 60 70 80 90 100 300 305 310 315 320 325 330 335 340 345 350 temperature, (k) w at er s ep ar at io n fa ct or , 10 vol.% 30 vol.% 60 vol.% 90 vol.% fig. 11. effect of temperature on water separation factor at different feed concentration. 3.3. effect of feed flow rate on membrane performance figures 12 to 14 show the effect of feed flow rate on the partial and total fluxes for ethanol and water. all fluxes increased with increasing of feed flow rate. as the feed flow rate increases up to 6 l/min, the thickness of the liquid boundary layer and mass transport resistance lowered, so the fluxes increased. a very slight change can be observed when the flow rate increases greater than 6 l/min and become unaffected. the effect of feed flow rate on normalized ethanol and water separation factor is shown in fig. 15. the rate of change of water separation factor decreases with increasing feed flow rate and the change continue up to 6 l/min after that a very slight change can be observed due to the slight change in the fluxes. the same trends were observed by other studies in the literature [10-25]. 0.75 0.8 0.85 0.9 0.95 1 0 1 2 3 4 5 6 7 8 9 10 11 feed flow rate, (l/min) et ha no l f lu x, (g /m 2 .h ) fig. 12. effect of feed flow rate on ethanol flux (60 vol. % ethanol and t=333k). 500 550 600 650 700 750 800 850 900 0 1 2 3 4 5 6 7 8 9 10 11 feed flow rate, (l/min) w at er fl ux , ( g/ m 2 .h ) fig. 13. effect of feed flow rate on water flux (60 vol. % ethanol and t=333k). ameel mohammed rahman al-khwarizmi engineering journal, vol. 8, no.4, pp106-117 (2012) 113 550 600 650 700 750 800 850 900 0 1 2 3 4 5 6 7 8 9 10 11 feed flow rate, (l/min) to ta l f lu x, (g /m 2 .h ) fig. 14. effect of feed flow rate on the total flux (60 vol. % ethanol and t=333k). 0.75 0.8 0.85 0.9 0.95 1 1.05 0 1 2 3 4 5 6 7 8 9 10 11 feed flow rate, (l/min) se pa ra tio n fa ct or , ( -) ethanol (max value= 0.0643 g/m2.h) water (max value= 19.6 g/m 2.h) fig. 15. effect of feed flow rate on ethanol and water separation factor (60 vol. % ethanol and t=333k). 3.4. activation energy for pervaporation membrane the activation energy for ethanol/water mixture pervaporation was calculated. the pervaportaion experimental data were treated with arhenius equation [15]: ,exp       − = rt e jj app o …(4) where eapp apparent activation energy of the transport in pervaporation, j and jo denote the fluxes, r is the gas constant and t is temperature (k). a plot of ln(j) vs. (1/t) and as shown in figs. 16 and 17 gives straight lines with slopes equal to (-eapp/r), from which the activation energy was calculated. the final results of calculations of activation energies were drawn in figs. 18 and 19 for ethanol and water respectively. it can be observed from fig. 18 that the activation energy is not constant and increases with increasing of ethanol concentration in the feed. higher activation energy means the diffusion of the water molecules is more restricted through the membrane. as the concentration increases, membrane swelling decreases and hence diffusion of water through the active layer is hindered. therefore, the activation energy of permeation increases, and vice versa for ethanol, as it is observed in fig. 19. these observations were also reported by various researchers in this field [1, 5, 16-25], and the results are agreed well with the reported trend in literature. 2.5 3.5 4.5 5.5 2.9 2.95 3 3.05 3.1 3.15 3.2 3.25 3.3 3.35 1000/t (k-1) ln j e th an ol 10 vol. % 30 vol. % 60 vol. % 90 vol. % fig. 16. arrhenius plots of ethanol flux at different feed concentration. ameel mohammed rahman al-khwarizmi engineering journal, vol. 8, no.4, pp106-117 (2012) 114 6.5 6.6 6.7 6.8 2.85 2.9 2.95 3 3.05 3.1 3.15 3.2 3.25 3.3 3.35 1000/t (k-1) ln j w at er 10 vol. % 30 vol. % 60 vol. % 90 vol. % fig. 17. arrhenius plots of water flux at different feed concentration. 1.7 1.9 2.1 2.3 2.5 2.7 2.9 3.1 0 10 20 30 40 50 60 70 80 90 100 ethanol concentration in the feed, (vol.%) ea pp , ( kj /m ol ) fig. 18. effect of ethanol concentration in the feed on water apparent activation energy. 0 5 10 15 20 25 30 35 0 10 20 30 40 50 60 70 80 90 100 ethanol concentration in the feed, (vol.%) e a pp , ( j/ m ol ) fig. 19. effect of ethanol concentration in the feed on ethanol apparent activation energy. 4. conclusions in the present study, the dehydration of ethanol/water system was performed using commercial hydrophilic silica pervaporation membrane in a lab scale pervaporation unit in a batch operation. the following conclusions have been stated: 1the proposed membrane is water permselective membrane, and has a high flux and a high selectivity for water compared to ethanol. 2the present study indicates that the membranes have no major imperfections since the total flux and water selectivity is barely affect by the feed concentration. 3water 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[25] c. cojocaru, m. khayet, g. zakrzewskatrznadel, and a. jaworska, “modeling and multi-response optimization of pervaporation of organic aqueous solutions using desirability function approach”, journal of hazardous materials, vol. 167, pp. 52–63, 2009. )2012( 106-117 ، صفحة٤، العدد8مجلة الخوارزمي الھندسیة المجلد امیل محمد رحمن 117 فصل الماء عن الكحول االثیلي بتقنیة التبخیر الجزئي باستعمال غشاء نانو سیلكا hydrophilic السیرامیكي مھا ھادي الحسني*** زیاد رافع زائر ** امیل محمد رحمن المیاحي * بغداد جامعة/ كلیة الھندسة الخوارزمي/ قسم الھندسة الكیمیائیة األحیائیة** ،* جامعة بغداد/ كلیة الھندسة/ قسم الھندسة الكیمیاویة*** الخالصة ت م اس تعمال . pervatechس یرامیكي تج اري م ن ش ركة hydrophilicفصل الماء عن الكحول االثیلي بطریقة التبخر الجزئي باستعمال غشاء كلفن، تركیز االیث انول ف ي اللق یم ٣٤٣-٣٠٣اجریت التجارب المختبریة بدرجات حرارة تراوحت بین . الماء كمودیل لدراسة التبخیر الجزئي/نظام الكحول تمت دراسة ت اثیر الظ روف التش غیلیة عل ى مع دل ت دفق الم واد، معام ل الفص ل للم واد . دقیقة/ لتر ١٠-٠,٥ومعدل جریان اللقیم ) نسبة حجمیة% ( ٩٠-١٠ .تدفق الماء یتأثر بشدة بدرجة الحرارة، اذ یزداد بزیادة درجة الحرارة ومعدل جریان اللقیم ویقل بزیادة تركیز االیثانولوجد ان معدل . النافذة، في ھذا العمل ان افضل الظروف التشغیلیة لعملیة الفصل بالتبخریر . كما وجد ان معدل تدفق الماء یقل مع زیادة تركیز االیثانول ویزداد مع زیادة معدل جریان اللقیم نسبة حجمیة لتركی ز االیث انول وق د تطابق ت ھ ذه النت ائج م ع دراس ات كثی رة % ٩٠دقیقة و /لتر ٦كلفن ومعدل جریان اللقیم ٣٣٣زئي ھي درجة حرارة الج .بمراجع مختلفة <4d6963726f736f667420576f7264202d20e3decfc7e320e6dae1ed20e6cee1ede120392d312d> al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 14, no. 1, march, (2018) p.p. 1-9 experimental study on solar air heating miqdam t chaichan* ali j. ali** khaleel i. abass*** * energy and renewable energies technology center/ university of technology/ baghdad/ iraq ** department of biomedical engineering/ university of technology/ baghdad/ iraq *** department of mechanical engineering/university of technology/ baghdad/ iraq *e-mail: 20185@uotechnology.edu.iq ** e-mail: 10678@uotechnology.edu.iq ***e-mail: 20078@uotechnology.edu.iq (received 22 march 2017; accepted 18 july 2017) https://doi.org/10.22153/kej.2018.07.008 abstract a new type of solar air heater was designed, fabricated, and tested in baghdad, iraq winter conditions. the heater consists of two main parts. the horizontal section was filled with the black colored iron chip while the vertical part has five pipes filled with iraqi paraffin wax. a fan was fixed at the exit of the air. two cases were studied: when the air moved by natural convection and when forced convection moved it. the studied air heater has proven its effectiveness as it heated the air passing through it to high temperatures. the results manifest that using little air movement makes the temperatures, stored energies, and efficiencies of the two studied cases converge. the suitable solar intensity of baghdad city makes the use of solar air heater suitable to reduce the electricity and fossil fuels consumption. keywords: forced convection, iron chip, pcm, paraffin wax, solar air heater. 1. introduction the demand for energy is increasing with time due to its massive consumption energy to meet the population and development's needs. the today power generation (whether for electricity or transportation) is coming mainly from fossil fuels like coal, oil and natural gas. the burning of these resources caused many environmental problems all over the world as global warming, acid rains, and the ozone hole. today, the nation's heading towards the renewable and sustainable energies like solar energy to compensate the fossil fuels [1, 2]. solar energy has many advantages compared to conventional fossil fuels on the environment. this energy is clean, abundant, and available all over the world. it is safe and environmental friendly [3]. the solar collectors for water heating have been used for many years with efficient operation in developed countries like the usa and europe [4]. solar air heaters are thermal systems used to convert the incident solar radiation into heat used to warm the air. these air heaters are used today in many applications like space heating for comfort conditions, drying agricultural plants and marine products [5]. the use of air heater reduces the dependence on fossil fuels. the air heater primarily consists of an isolated duct for hot air, a heating panel, a glass cover, and an air blower for moving air. the group has a thermally isolated absorbing plate with black color in general [6]. the glass cover allows the solar radiation to pass through it and prevents its exit. this process causes the greenhouse effect which improves the efficiency of miqdam t chaichan al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 19 (2018) 2 air heater. the glass also works as part of the air duct [7]. however, these systems suffer from many problems like low convection heat transfer coefficient of air which reduces the thermal exchange between the heater and air [8, 9]. the absorber plate, in this case, will become hotter and the thermal losses will be increased through the covers. many researchers tried to enhance the heat transfer coefficient of air and the air heater performance. prasad et al. [10] suggested double glassing cover for the air heater to minimize its thermal losses. sopin et al., ozgen et al., and chaichan et al. [11-13] tested a double pass channel air heater where the air flows from above and then below the absorber plate. many researchers made many modifications on the air heaters to reduce its thermal losses and increase the air heat transfer coefficient like adding fins for the double pass air heater [14]. also, references lertsatitthanakorn et al. [15], esen [16], paisaran [17], and ho et al. [18] studied adding fins to the absorbing plate. qenawy and mohamad [19] and thankur et al. [20] used a porous material to increase the heat exchange inside the air heater. the porous material consisted of wire mesh screen. ramadan et al. [21] used limestone and gravels as a porous media while elsebaii et al. [22] added iron scrap to gravel and limestone. the solar heater reliance on sunlight as the only energy source makes its use after sunset is useless. many researchers investigated the abilities to use thermal storage materials to increase the working time of the air heater. srivastava et al. [23] used a phase change material (lauric acid) as a heat storage material. this study increased the attention on using of phase change materials (pcm) in air heaters as it elongates the working time. the authors fingered the importance of the charging and discharging of the used pcm heat transfer characteristics. kabeel [24] investigated the effect of adding paraffin wax as a pcm for an air heater performance. the authors presented the weather parameters affecting the performance of their module. chaichan et al. [25] used nano-al2o3 with paraffin wax to enhance the charging and discharging process in a heat storage wall (trombe wall). the authors claimed better thermal conductivity of nano-pcm which made the wall gained higher temperatures up to 29.08% compared to the use of paraffin wax alone. the addition of nano-al2o3 to pcm made the materials stored temperature increased with about 42.68%. iraq is characterized by bright sun of most days of the year, with an average of 335 days, and relatively high solar radiation intensity ranging from 245 w/m2 in winter to 980 w/m2 at summer [26]. these conditions make iraq a suitable location for using air heaters in all its applications that reduce the demand on electricity which the country is suffering from its lack [27]. the aim of this study is to design, fabricate and test a new type of air heater. the objective is to find a suitable, cheap, and easy to construct the system. the proposed method is useful in reducing energy and fuel consumption, which means better environment and less pollution. 2. experimental technique the new designed and made solar air heater consists of a horizontal passage and a vertical passage connected. the heater has a cubic form cross section with a rib length of 20 cm. two sides of the heater are from isolated wood covered by a copper plate painted with black, while the other two sides are from the glass with 3 mm thickness. the wood is covered with a glass wool insulator with a 1.5 cm thickness to confirm the system thermal insulation. glass has been installed on the wood in the gaps paved in wood, and area in contact between the glass and wood was filled with silicon to ensure no leakage of hot air from the system can be exist. fig 1 shows a schematic diagram of the studied solar air heater with its dimensions. fig. 1. a schematic diagram of the designed, fabricated, and studied solar air heater. miqdam t chaichan al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 19 (2018) 3 the horizontal part of the air heater was filled with 3 kg of iron chip colored in nonshiny black to increase the absorbed radiation. in the vertical part of the heater, five black pipes were fixed on the plate. the 5 cm diameter pipes were filled with iraqi paraffin wax which its specification are listed in table 1. the used paraffin wax was 10 kg. the horizontal part of the heater was closed by a piece of wood has 10 holes having diameter of 1.0 cm each. the vertical part was mounted with a wood cover with an air fan has a diameter of 7.5 cm and power of (4 watt) to force air movement from the heater to the conditioned space. fig. 2 shows a photo of the tested air heater. four thermocouple type k were used to measure the temperature of the air heater parts. one thermocouple was fixed in the front of the entrance inside the chip. the second one was set at the end of the chip while the third was attached on one of the pcm pipes. the last thermocouple was fixed at the exit part of the heater before the fan. the air temperature was measured in the shadow by a thermometer. fig. 2. a photo of the tested air heater table 1, the specifications of the paraffin wax used melting temperature (°c) 40 latent heat of fusion (kj/kg) 190 solid specific heat (kj/kg °c) 2.384 liquid specific heat (kj/kg °c) 2.49 the temperatures were tiled as the following: tathe ambient air temperature. t1the chip temperature at the center, near the air entrance. t2the chip temperature at the center of the horizontal part of the heater. t3the temperature of the middle paraffin wax pipe, in the vertical part of the heater. t4the air temperature at exist of the heater. the following equations were used to calculate the heat storage values for the air heater and its components. the storage energy inside the air heater �� = ���(� � − � ) (kj) …(1) the whole day storage energy � � �� = ���� + ���� + ⋯ + ���� (kj) …(2) the energy drawn by fan �� = �� ����(���� �� − ���� ��) (kw) …(3) the total drawn energy �� ! �" = ��#$%## + ��##%#& + ⋯ + ��'%( (kw) …(4) the air flow rate �� � = )*�+� (kg/s) …(5) the system efficiency , = -�./ 0×2 (%) …(6) error analysis error analysis is used to determine the accuracy of the measurements and depends on the accuracy of readings from all the devices used in the experiments. in this study, the first measuring devices were used to measure the temperature and the second to measure the air speed. the two devices were calibrated by comparing their measurements with a standard device. table 2 gives information about the devices used and the rate of deviation in the readings. table 2, the used measuring devices in the present study. measuring parameter device name company range error rate temperature digital thermometer comark (uk) -25 to 70°c 1.02 air speed anemometer lutron yk80am 0-15 m/s 1.32 miqdam t chaichan al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 19 (2018) 4 the results of the calibration showed that the error rate is calculated according to equation [28]: 34 = 56 74 78# 3�9: + 6 74 78& 3:9: + ⋯ + 6 74 78; 3�9:< =.? …(7) 34 = @(1.02): + (1.32):e=.? = 1.668 the error rate was less than 5% making the readings acceptable geometrically. experimental procedure the tests on the solar air heater were conducted in baghdad city-iraq in last two weeks of dec-2016 and the beginning two weeks of january-2017. this month was selected due to its low ambient temperature as it has the lowest solar intensity compared to the other months. the system was fixed facing the south, and the variable temperatures were measured for two cases: 1-when the air was flow by natural convection. 2when the air was flow by forced convection using the fan. the tests were repeated more than three times, and the average values were taken to ensure the repeatability and to reduce the impact of uncertainty variables. 3. results and discussion the solar air heater starts its work with the sun rise in the first morning, as the sunlight heats the chip in spite of its low radiation intensity values. for this reason, the temperature t1 (35.3°c) starts higher than air temperature (2°c), as figures 3 &4 show. the iron chip gains heat from the sun easier and faster that the pcm for the period from 8 am to 2 pm. after this hour, the chip temperature starts to decline rapidly whenever the sun goes down. the ambient air temperature in baghdad climate is small in winter. however, the suggested air heater proved its effectiveness as the exit air temperatures were very high starting from 10 am (45°c) till it reached its maximal at 2 pm (65°c). fig. 3. the distribution of the system variable parts temperatures with time without fan the paraffin wax starts to gain heat with a time lag compared to the iron chip. the thermal conductivity of the wax is small compared to the chip which causes this heat gain delay. the pcm temperatures increased till it reached its melting point, at which the increase in the wax temperature pause until all the wax is melted, then temperature continued to rise. fig. 4. the distribution of the system variable parts temperatures with time without fan the wax temperature all the charging period (the heating time from 8 am to 2 pm) was lower than the chip temperature. at the discharging time (from 2 pm till night) the pcm temperature was higher than the chip ones. the pcm stored more thermal energy than the chip which benefits after sunset as the exit air temperature was 24.5°c at 10 pm. the resulted temperature confirm the success of the established system as it gathers the rapid gain of heat by the chip and the high stored energy quantity by the pcm. miqdam t chaichan al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 19 (2018) 5 figures 5 & 6 represents the measured temperature of the system variable parts with time when the air was forced to move using a fan. the used of the fan is crucial in this kind of systems to control the air mass flow rate as desired. in this case, the system was left to warm up till 10 am; then the fan was operated. the results indicate high temperatures of the systems' parts that have tiny lower quantities compared to the free convection operation of the scheme. fig. 5. the distribution of the system variable parts temperatures with time with fan in the case of employing a fan, the chip temperatures decline rapidly in the discharging period due to the reduction in the heat supply from the sun. here, the use of pcm as a heating source was wise as it preserved the high air temperatures. the clear sky and high solar intensity of the iraqi winter made these temperatures possible, which means that the use of such air heaters in homes and buildings can reduce the relay on grid electricity that it is generated from fossil fuels. fig. 6. the distribution of the system variable parts temperatures with time with fan figures 7 and 8 show the stored thermal energy variation with time. the stored energy of the chip was little compared with the paraffin wax. the maximum storing energy gained by the wax at the phase change period. the benefit of this stored energy appeared in elongating the air warming period for several hours after the heating source (the sun was set). fig. 7. stored thermal energy variation with time. fig. 9 manifests the system's stored thermal energy variation with time for the two cases. the results indicate clear convergence for the two cases. the air flow rate with the fan was weak which manage the system parts to gain heat without fast cooling. the figure results support the previous conclusion about the system success in iraqi winter weathers. fig. 8. stored thermal energy variation with time. miqdam t chaichan al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 19 (2018) 6 fig. 9. the flowing air stored energy with time distribution for the studied cases. fig. 10. the system efficiency variation with time for the studied cases. for validation and ascertaining the quality and efficiency of the designed air heaters, it has been compared with many other devices that were tested in iraq and other countries weathers. table 3 lists this comparison. the table indicates that for iraq the new solar air heater achieved the highest maximum temperature and stored energy and efficiency due to the use of the chip in addition to the pcm. for ref. [30] the authors used in addition to pcm solar radiation concentrators to increase the incident radiation. however, the paper results converge with the recent study results. ref [31] used square steel wire mesh with forced convection (air moving by a fan). the authors' designed system operated till 3 pm while the recent study system continued heating till 10 pm. table 3, a comparison between the present study and other published researches. reference location system type max. temp. achieved max. stored energy achieved max. eff. achieved present study iraq chip and pcm 74°c 2100 kj 36% chaichan et al. [25] iraq pcm only 60°c 1300 kj chaichan et al. [29] iraq water 48°c chaichan et al. [13] iraq aluminum plate 50°c 1000 kj el-khadraui et al [29 ] tunisia pcm 90°c 1900 kj 32.85% roy et al. [30] bangladesh square wire mesh 52°c 6465 kj 54% 4. conclusions in this study, a new design of solar air heater was fabricated and designed in iraqi winter weathers. in this design iron chip and pcm were used to gain heat from the solar rays. two cases were tested when the air passed through the air heater in natural convection and forced convection. the resulted air temperatures explicit an increase after passing through the heater. the chip was useful in increasing the air temperature due to its high surface area of contact. the paraffin wax was a good choice as it increased the system warming time for more than four hours after sunset. miqdam t chaichan al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 19 (2018) 7 the results reveal that using a fan with low flow rate reduces the gained temperatures and stored energy but in a limited amount. the produced efficiencies in the two tested cases were convergence. the suggested system in spite of it was a prototype it confirmed its ability to warm iraqi houses and building for a period that can exceed 14 hours/day. the use of such solar air heaters will reduce the amount of electricity and fuel consumption in winter. nomenclature a the heater area cpwax wax specific heat (kj/kg. h) hi h*� the partial derivative 34 uncertainty in the results m� klm air drawn (kg/s) mwax wax mass (kg) qs1 energy stored in the chip (kj) qu the drawn energy from the heater (kj) tairout the delivered air temperature (k) ρa air density (kg/m3) cpchip chip specific heat (kj/kg. h) cpa air specific heat (kj/kg. h) ei uncertainty interval in the nth variable. i solar intensity (w/m2) mchip chip mass (kg) qs storage energy inside the air heater qs2 energy stored in wax (kj) q air energy drawn by the air (kj) tairin entering air temperature (k) va air speed (m/s) 5. references [1] hanif m, khattak m k, amin m, ramzan m, zakir s, ullah s & khan z, development of an efficient flat plate solar air heater for drying and water heating purposes, sains malaysiana, vol. 45, no. 3,pp. 489–497, 2016. 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[30] el-khadraoui a, bouadila s, kooli s, guizani a, farhat a, solar air heater with phase change material: an energy analysis and a comparative study, applied thermal engineering, vol. 107, pp. 1057–1064, 2016. [31] roy a, islam m s, hoque m e, sarker m r i, experimental investigation of single pass solar air heater with and without square steel wire mesh on absorber plate, international conference on mechanical, industrial and energy engineering, 26-27 december, khulna, bangladesh, 2016. )2018( 1-9، صفحة 1د، العد14دجلة الخوارزمي الهندسية المجلممقدام طارق جيجان 9 دراسة تجريبية حول تسخين الهواء بالطاقة الشمسية ***خليل ابراهيم عباس **علي جالل علي *مقدام طارق جيجان العراق /الجامعة التكنولوجية /مركز تكنولوجيا الطاقة والطاقات المتجددة * العراق /الجامعة التكنولوجية /الطب الحياتي قسم هندسة ** العراق /الجامعة التكنولوجية /قسم الهندسة الميكانيكية*** uotechnology.edu.iq@20185 :البريد االلكتروني* uotechnology.edu.iq@10678**البريد االلكتروني: uotechnology.edu.iq@20078***البريد االلكتروني: الخالصة ن. الجزء يمن جزئين رئيسسخن الهواء العراق. يتكون م -تم تصميم وتصنيع وفحص عمل نوع جديد من مسخنات الهواء الشمسية في اجواء مدينة بغداد حة عند فتحة خروج مرواالفقي مأل برايش الحديد سوداء اللون بينما ثبتت خمسة انابيب مملوءة بمادة الشمع البرافينيي متغيرة الطور في الجزء العمودي. ثبتت حرك بفعل الحمل القسري.اثبت مسخن الهواء المدروس كفاءته الهواء. تمت دراسة حالتين: عندما يتحرك الهواء بفعل الحمل الطبيعي والحالة الثانية عندما يت ات خزونة و الكفاءاذ انه سخن الهواء المار خالله الى درجات حرارة عالية. بينت النتائج ان تحريك الهواء بسرع منخفضة يجعل درجات الحرارة والطاقات الم اد مناسبه جدا الستخدام مسخنات الهواء الشمسية والتي من شأنها ان تقلل استهالك الكهرباء للحالتين المدروستين تتقارب. ان شدة االشعاع الشمسي لمدينة بغد والوقود االحفوري. عبد السلام وغيث al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 9, no. 1, p.p. 9-18 (2013) design of robotic arm control system mimics human arm motion a. salam al-ammri* ghaith .a .taki** *,**department of mechatronics engineering/ al-khawarizmi college of engineering/ university of baghdad *email: asalamalammri@yahoo.com **email: ghaith.taki@gmail.com (received 14 may 2012; accepted 6 november 2012) abstract this paper presents a control system to make the robotic hand mimic human hand motion in real time and offline mode. the human hand tracking system is a wearable sensing arm (potentiometers) used to determine the position in space and to sense the grasping task of human hand. the maskable sensing arm was designed with same geometrical arrangement of robotic hand that needs to be controlled. the control software of a robot was implemented using visual basic and supported with graphical user interface (gui). the control algorithm depends on joint to joint mapping method to match between the motions at each joint of portable sensing arm with corresponding joint of a robot in order to make the robot mimic the motion. keywords: robotic arm, control, human hand tracking. 1. introduction teleporting of a robot through human hand motion plays an important role in many fields such as medicine, space exploration, military, nuclear environment, construction and many other fields. a large number of interfaces concerning robot control using hand motion such as vision based system by tracking markers placed at a dorsal side of human hand using cameras to estimate the 3d position of hand to control the robot were proposed [ 1, 2]. emg (electromyography) signals which are measured using non-invasive electrodes are placed at specific locations of human arm and represent the activity of human arm muscles due to motion to drive the robot [3]. micro-electro-mechanical systems (mems) was used to estimate the 3d position and orientation of human hand by integrating inertial sensors such as gyroscope, accelerometer and magnetometer [4]. electromechanical devices (potentiometer and metal parts), are worn by the operator arm to sense the motion of arm [5]. this paper presents a method to control the robot motion using a built sensing arm that can be gripped by human hand to determine the position and orientation of human hand and to sense the grasping task performed by human hand finger. 2. the experimental work the system consists of four parts: sensing arm, interface circuit, robotic arm and control software, fig.1. a. sensing arm a wearable arm fig.2, is used to measure the 3d position of human hand (within the workspace of sensing arm), and to sense the grasping of a hand finger. the sensing arm has the same degrees of freedom dof of robotic arm, which is 4 dof that needs to be controlled. it was made from four metal parts and four potentiometers (1m ω) sensing arm joints, base, shoulder, elbow, wrist, and push-button switch for finger joint. mailto:asalamalammri@yahoo.com mailto:ghaith.taki@gmail.com a. salam al-ammri al-khwarizmi engineering journal, vol. 9, no. 1, p.p. 9-18 (2013) 10 the principle of operation of each sensing arm joint (except finger joint) depends on the voltage divider. so, when the operator mask the sensing arm and move his hand, this motion will make each joint (except finger joint) rotate with a specific motion. therefore, the resistance of each joint varies, so, the output voltage of each potentiometer will change according to the voltage divider principle and represents the measuring of joint rotation. finger joint was implemented using a push-bottom switch which is connected with the ground. fig. 1. control system block diagram. fig. 2. sensing arm b. interface circuit the analog voltage of each sensing arm joint (potentiometer) must be converted to the digital form before sending them to the computer via parallel port. therefore, the interface circuit ,fig.3, consists of four adc ic’s (0804lcn) [6], one for each sensing arm (except finger joint) joint. additionally, four buffer ic’s (74ls245) [7] are used to protect the computer from any harmful signals. the finger joint of sensing arm is connected directly to the parallel port without using adc and buffer ic. the analog voltage of sensing arm base joint is converted to the digital voltages of 4-bits and are sent via pin(2),pin(3),pin(4),pin(5) of parallel port. the analog voltage of sensing arm shoulder joint is converted to the digital voltages of 3-bits and are sent via pin (6), pin (7), pin (8) of parallel port. the analog voltage of sensing arm elbow joint is converted to the digital voltages of 3-bits and are sent via pin (15), pin (13), pin (12) of parallel port. the analog voltage of sensing arm wrist joint is converted to the digital voltages of 2-bits and are sent via pin (10), pin (11) of parallel port. while, the push-button switch of a finger joint of sensing arm is connected between the ground and pin (9) of parallel port. the leds are used as an indicator to simplify a programming task. computer visual basic software joint to joint motion mapping o,robotic arm sensing arm (potentiometers) interface circuit (adc ic’s, buffer ic’s) parallel port a. salam al-ammri al-khwarizmi engineering journal, vol. 9, no. 1, p.p. 9-18 (2013) 11 fig. 3. interface circuit c. robotic arm the phantomx pincher ax-12 robot arm, fig.4&5, consists of four joints plus a gripper. there are seven servo motors (ax-12 dynamixel) used to actuate robot joints; one servo for base joint, two servos for shoulder joint, two servos for elbow joint, one servo is for wrist joint and one servo for gripper joint. each servo motor has its own id number and can rotate (300° through 1024 steps). the robot is supported with usb2dynamixel interface circuit to connect the robot with computer through usb port, additionally, it is supported with sdk software to use it with different programs such as matlab, visual basic, labview , etc. fig. 4. robotic arm fig. 5. ax-12 dynamixels network d. control software the control algorithm of a robot reads the decimal value of status and data bus of parallel port and extracts the binary value of pin(2,3,4,5), pin(6,7,8) ,pin(9) pin(9 , pin(10,11) and pin(15,13,12) . the control algorithm uses (if. .else) instructions to match between the digital values of sensing arm joints with corresponding joint's motion of a robot in a manner to make the robot mimic the motion of sensing arm. for example, when the base joint of sensing arm rotates (90º) , the base joint of a robot also rotates (90°) to mimic this motion, and when the operator pushes the switch of a finger joint of sensing arm, the robot’s two fingers are closed to perform the grasping task. the software was supported with offline control to repeat the motions of a robot (during the real time control), fig.6. a. salam al-ammri al-khwarizmi engineering journal, vol. 9, no. 1, p.p. 9-18 (2013) 12 fig. 6. (gui) of control software. 3. results when the sensing base joint rotates (cw) with angle (-90º) with respect to the reference point, the digital output of this motion is (1111b ) . in the same manner, when sensing arm rotates (ccw) with angle (90º) with respect to the reference point, the digital output of this motion is (0001b).calculating the step of rotation for each digital output within (0111 b to 1111 b) is shown in table 1,and fig.7 & 8: өs= ° ° = 11.25° , and өr= =~39 step ( for robot) and to calculate the step of rotation for each digital output within (0111 b to 0001 b): өs= ° ° = 15°, and өr= =51 step ( for robot). table 1, sensing arm and robot base joint motion. ө sensing base digital output sensing base rotation angle robot base motion ө1 0111 b 0° 512+(0*51)=512 ө2 0110 b 15° 512+(1*51)=563 ө3 0101 b 30° 512+(2*51)=614 ө4 0100 b 45° 512+(3*51)=665 ө5 0011 b 60° 512+(4*51)=716 ө6 0010 b 75° 512+(5*51)=767 ө7 0001 b 90° 512+(6*51)=~820 ө8 0000 b 105° 512+(7*51)=869 ө9 1000 b -11.25° 512-(1*39)=473 ө10 1001 b -22.5° 512-(2*39)=434 ө11 1010 b -33.75° 512-(3*39)=395 ө12 1011 b -45° 512-(4*39)=356 ө13 1100 b -56.25° 512-(5*39)=317 ө14 1101 b -67.5° 512-(6*39)=278 ө15 1110 b -78.75° 512-(7*39)=239 ө16 1111 b -90° 512-(8*39)=204 a. salam al-ammri al-khwarizmi engineering journal, vol. 9, no. 1, p.p. 9-18 (2013) 13 fig. 7. range of sensing arm and robot base joint motion. fig. 8. sensing arm and robot base angles. for shoulder joint, the digital value (001) was chosen as a reference point, so, the rotation angle for this position is considered (0°). now, to rotate down with rotation angle (-90º), the digital output of sensing shoulder will be (101) . to calculate the rotation angles within (111 000) ), table 2 and fig.9 &10: өs= ° ° = 22.5° and өr= =67 step (for robot). table 2, sensing arm shoulder joint motion. ө sensing shoulder digital output sensing shoulder rotation angle = − . , = , , robot shoulder motion + , = − , ,1 ө1 000 b 22.5º 512-(1*67)=445 ө2 001 b 0º 512+(0*67)=512 ө3 010 b -22.5º 512+(1*67)=579 ө4 011 b -45º 512+(2*67)=646 ө5 100 b -67.5º 512+(3*67)=713 ө6 101 b -90º 512+(4*67)=780 ө7 110 b -112.5º 512+(5*67)=847 ө8 111 b -135º 512+(6*67)=914 step 512,0º step 204,-90° step 820,90º ө16 ө15 ө14 ө13 ө12 ө11 ө9 ө10 ө2 ө3 ө1 ө4 ө5 ө6 ө7 ө8 -150 -100 -50 0 50 100 150 -150 -100 -50 0 50 100 sensing base angles robot base angles a. salam al-ammri al-khwarizmi engineering journal, vol. 9, no. 1, p.p. 9-18 (2013) 14 fig. 9. range of sensing arm and robot shoulder joint motion. fig.10.sensing arm and robot shoulder angles. there are eight digital outputs due to sensing arm elbow joint (000 to 111). the digital output (001) was chosen as a reference point with a rotation angle (0°) and when the joint rotates up with angle (90º), the digital output is (101),table 3 and fig .11 &12. өs= ° ° = 22.5° and өr = =77 step (for robot). table 3, sensing arm and robot elbow joint motion. -120 -100 -80 -60 -40 -20 0 20 40 -150 -100 -50 0 50 robot shoulder angle sensing shoulder angle ө sensing elbow digital output = − . , = , , sensing elbow rotation angle − , = ,− ,− robot wrist motion ө1 111 135° 512-(6*77)=50 ө2 110 112.5° 512-(5*77)=127 ө3 101 90° 512-(4*77)=204 ө4 100 67.5° 512-(3*77)=281 ө5 011 45° 512-(2*77)=358 ө6 010 22.5° 512-(1*77)=435 ө7 001 0° 512+(0*77)=512 ө8 000 -22.5° 512+(1*77)=589 θ2 θ3 θ1 θ4 θ5 θ6 θ7 θ8 step 512 step 780 a. salam al-ammri al-khwarizmi engineering journal, vol. 9, no. 1, p.p. 9-18 (2013) 15 fig. 11. range of sensing arm and robot elbow joint motion. for wrist joint, there are four digital outputs (00b to 11b). the digital value (10b) was chosen as a reference point, below are the results of motion, table 4 &5 and fig 12 &13 : table 4, sensing arm and robot wrist joint motion. table 5, sensing arm and robot two fingers. sensing switch robot fingers motion robot fingers status pressed (0b) 700 close released (1b) 600 open ө sensing wrist digital output sensing wrist rotation angle robot wrist motion ө1 10 b 0° 512 ө2 11 b -45° 666 ө3 01 b 45° 358 ө4 00 b 90° 204 θ7 θ 6 θ5 θ4 θ1 θ2 θ 3 θ8 step 512 step 204 a. salam al-ammri al-khwarizmi engineering journal, vol. 9, no. 1, p.p. 9-18 (2013) 16 fig. 12. range of sensing arm and robot wrist joint motion fig. 13.sensing arm and robot wrist angles. 4. conclusion this paper presents a real time and offline (teaching) control of robotic hand. the control system depends on (if. else) , instruction to map directly between sensing arm and robot joints,fig.14. the system achieved a good response time of robot control (~ 1 second) and high repeatability. the dimensions were chosen to cope with geometrical dimensions of a real robot because they affect on the results of motion. the type of potentiometer affects on the analog to digital conversion performance through the noise that may occur due to bad manufacturing of a potentiometer. -100 -80 -60 -40 -20 0 20 40 60 -100 -50 0 50 100 robot wrist angles sensing wrist angles ө 3 ө 2 ө 4 ө 1 step 204 step 512 a. salam al-ammri al-khwarizmi engineering journal, vol. 9, no. 1, p.p. 9-18 (2013) 17 fig. 14.samples of robot motion. 5. references [1] jonathan and siddharth ,” teleportation of a robot manipulator using a visionbased human –robot interface” , ieee transaction on industrial electronics, vol.52, no.5, 2005. [2] chris yu-liang liu,” three-dimensional hand tracking and surface – geometry measurement for a robot-vision system”, university of waterloo canada,2008 [3] jorn and patrick , “ emg-based teleportation and manipulation with the dlr lwr-iii “ , ieee/rsj international conference on intelligent robots and systems,2011 [4] farrukh iqbal sheikh , “ real-time human arm motion translation for the workpartner robot “, helsinki university of technology,2008 [5] gupta and demidenko , “ master-slave control of a teleported anthropomorphic robotic arm with gripper forces sensing “ , imtc,2005 [6] “ adc0804 lcn data sheet” [7] “ 74ls245 data sheet “ )2013( 918، صفحة 1، العدد9مجلة الخوارزمي الھندسیة المجلدعبد السالم عبد العباس العامري 18 ذراع االنسان حركة حاكي یانسان الي ذراع لتصمیم نظام تحكم **غیث عبد الودود تقي* السالم عبد العباس العامريعبد جامعة بغداد/ كلیة الھندسة الخوارزمي/ قسم ھندسة المیكاترونكس** ،* asalamalammri@yahoo.com :البرید االلكتروني* ghaith.taki@gmail.com :البرید االلكتروني** الخالصة متابعةنظام اللقد تم تصمیم وبناء .غیر متصلالالوضع بالوقت الحقیقي وحركة ذراع اإلنسان لمحاكاة ،ذراع إنسان آليلنظام تحكم البحث ھذا رضعی التحسس نظام تصمیم لقد استند في . االلتقاط لید اإلنسانالمسك وعملیة كذلك لحركة ید االنسان من خالل نظام تحسس لتحدید الموقع واالتجاه في الفضاء و واجھة بفیجوال بیسك بواسطة برنامج ألُنِفذت خوارزمیة التحكم بذراع اإلنسان اآللي .المراد السیطرة علیھا متابعة حركة ذراع اإلنسانلالھندسي الھیكل على وذراع االنسان لیتم محاكاتھا ذراع التحسس كل مفصل للمطابقة حركة اعتمدت خوارزمیة السیطرة على طریقة خارطة مفصل لمفصل . رسومیة للمستخدم . ذراع اإلنسان من قبل mailto:asalamalammri@yahoo.com mailto:ghaith.taki@gmail.com د.مهند كاظم ونور al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 9, no. 1, p.p. 39-46 (2013) an autocorrelative approach for emg time-frequency analysis mohannad k. sabir* noor k. muhsin** *,**department of biomedical engineering/ al-khwarizmi college of engineering/ university of baghdad mohannad3151962@gmail.com: lemai* **email: noorbmemsc81@yahoo.com (received 17 march 2011; accepted 2 december 2012) abstract as they are the smallest functional parts of the muscle, motor units (mus) are considered as the basic building blocks of the neuromuscular system. monitoring mu recruitment, de-recruitment, and firing rate (by either invasive or surface techniques) leads to the understanding of motor control strategies and of their pathological alterations. emg signal decomposition is the process of identification and classification of individual motor unit action potentials (muaps) in the interference pattern detected with either intramuscular or surface electrodes. signal processing techniques were used in emg signal decomposition to understand fundamental and physiological issues. many techniques have been developed to decompose intramuscularly detected signals with various degrees of automation. this paper investigates the application of autocorrelation function (acf) method to decompose emg signals to their frequency components. it was found that using the proposed method gives a quite good frequency resolution as compared to that resulting from using short time fast fourier transform (stfft); thus more mu’s can be distinguished. keywords: digital signal processing; nonstationary processing of biomedical signals; time-frequency analysis of biosignals. 1. introduction the electromyogram (emg) is an electrical manifestation of the contracting muscle. this can be either a voluntary or involuntary muscle contraction. the emg signal is a complicated signal which is affected by anatomical and physiological properties of the muscle, the control scheme of peripheral nervous system, as well as the instrumentation used for detection and the process used to record the emg signals. the basic functional unit of the muscle contraction is a motor unit. this muscle fiber contracts when the action potentials of the motor nerve which supplies it reach a depolarization threshold. the depolarization generates an electromagnetic field measured as a very small voltage called emg [1]. emg signal is a complicated signal in the body that cannot be differentiated easily by the physician because of its shape. 2. emg measurements although action potentials from individual muscle fibers can be recorded under special conditions, it is the electrical activity of the entire muscle that is of primary interest. in this case, the signal is a summation of all the action potentials within the range of the electrodes, each weighted by its distance from the electrodes as shown in figure 1. fig. 1. surface emg summed activities of many mu’s are recorded. mailto:mohannad3151962@gmail.com mailto:noorbmemsc81@yahoo.com mohannad k. sabir al-khwarizmi engineering journal, vol. 9, no.3, p.p. 39-46 (2013) 40 since the overall strength of muscular contraction depends on the number of fibers energized and the time of contraction, there is a correlation between the overall amount of emg activity for the whole muscle and the strength of muscular contraction. the emg potentials from a muscle or group of muscles produce a complicated waveform that varies in amplitude with the amount of muscular activity. peak amplitudes vary from 25 μv to about 5 mv, depending on the location of the measuring electrodes with respect to the muscle and the activity of the muscle. a frequency response from about 5 hz to well over 5000 hz is required for faithful reproduction [3]. the emg signals of the tested muscles (right pectoralis, right biceps and right triceps) are shown in figure 2. fig. 2. the tested emgs signals. according to figure 2, time domain cannot give us a lot of information about muscle components, hence it is necessary to transform the signal into a frequency domain to obtain more information regarding the muscle fiber. 3. emg signal processing raw emg offers us valuable information in a particularly useless form. this information is useful only if it can be quantified. various signal processing methods are applied to raw emg to reach the accurate and actual emg signal. wavelet analysis is chosen so as to match the shape of the muap; the resulting wt yields the best possible energy localization in the time-scale plane. it was found out that wt is an alternative to other timefrequency representations with the advantage of being linear. wavelet analysis have been used to match the shape of the muap, for a unipolar recorded signal and under certain hypotheses presented by gabor in 1946. ismail and asfour came with a theory saying that, the most common methods used to determine the frequency spectrum of emg are the fast and short term fourier transforms (fft and sft); but they also concluded that a major drawback of these transformation methods is that they assume the signal to be stationary. however, emg signals are non-stationary [3]. to overcome the above limitation of fft method, we propose the autocorrelation function method for emg spectral analysis as explained in the following section. 4. methodology resolving emg signal into its significant constituent muapts requires the ability to detect the discharges (i.e., muaps) of the mus that are significantly contributing to the composite signal, and to correctly associate each detected muap with the mu that generated it. emg signal decomposition therefore involves two basic steps: detecting muaps and recognizing the detected muaps [4]. correlation based processing is known to be comparatively robust against noise. the autocorrelation function method [6], is classified into this category, and may be one which provides the best performance in noisy environments [6]. thus; autocorrelation spectral analysis, instead of fft techniques, is used in this work to characterize the distributions of muaps of different mus. successful emg signal decomposition can therefore involve the following steps: (1) emg signal acquisition. (2) slicing the incoming signal into sequence of time windows, where for each window the dcoff set (which represents the mean of the signal) is removed and then the resultant window is multiplied by hamming window. (3) applying autocorrelation function (acf) to each window, & (4) resolution (frequency components) and classification of superimposed muaps by searching for the maximums of acf. a block diagram of the proposed system is shown in figure 3. 0 500 1000 1500 2000 2500 3000 3500 4000 -2 0 2 sample no. am p. (v ) emg of pectorals muscle 0 500 1000 1500 2000 2500 3000 3500 4000 -0.5 0 0.5 sample no. am p. (v ) emg of biceps muscle 0 500 1000 1500 2000 2500 3000 3500 4000 -1 0 1 sample no. am p. (v ) emg of triceps muscle mohannad k. sabir al-khwarizmi engineering journal, vol. 9, no.3, p.p. 39-46 (2013) 41 fig. 3. the proposed system’s block diagram a. emg signal acquisition the recorded emg signal coming from the electrodes is amplified by that little emg box using a gain of 5,000 according to the manufacturer [7]. data files that we used are downloaded from [8] with a sampling frequency of 2000 hz and 4000 sample length (2 sec. time duration). the emg amplifiers inside the box have different biases for the pectorals, biceps and triceps muscles in 5 lb weight. analysis of these data files started with converting them to (.mat) files then the small dc offset of the signal is removed by forcing the mean of the window to be equal to zero, as shown in figure 4. x1(t) = x0(t) dc_offset …(1) where x1(t) is the emg signal without a dc offset, and x0(t) is the recorded signal. fig. 4. emg’s after removing dc offset. b. hamming window multiplication multiplying the truncated input signal by a hamming window is to reduce the abruptness of the truncated ends and thereby improve the frequency response. the hamming window is given by: )/2cos(46.054.0)( niiw π−= …(2) for i=0,1,2,…n-1, and n is the length of the window [5]. x(i)= x1(i) * w(i) …(3) for i=0,1,2 … n-1. since the autocorrelation method required at least two periods of the lowest frequency component (20 hz) to give appropriate estimation of the contained frequencies, then a window of 128msec is chosen. . moreover, it is required to maintain the stationary property of the emg signal during each window. fig (5) illustrates the mean of each window. according to the sampling time of 500µsec (ts=1/fs), each successive window will represent 256 samples (128msec/500µsec). thus, there will be 15 windows for the input emg signal of 2 sec time duration. number of windows = 4000(samples)/256= 15.625 fig. 5. the mean of each window of 256 samples. c. autocorrelation method 1) principle autocorrelation function ( )kr is calculated by ( ) ∑ − = += 1 0 )()(1 n n knxnx n kr …(4) 0 500 1000 1500 2000 2500 3000 3500 4000 -2 0 2 dc offset=.0608 sample no. am p. (v ) 0 500 1000 1500 2000 2500 3000 3500 4000 -0.5 0 0.5 dc offset=0.0619 sample no. am p. (v ) 0 500 1000 1500 2000 2500 3000 3500 4000 -1 0 1 dc offset=0.0597 sample no. am p. (v ) emg signal acquisition hamming window autocorrelation resolution & classification mohannad k. sabir al-khwarizmi engineering journal, vol. 9, no.3, p.p. 39-46 (2013) 42 where x(n) is the emg signal, k is the lag number, and n is the discrete time index. the autocorrelation function ( )kr has a large value when )(nx is similar to )( knx + . if )(nx has a period of p, then ( )kr has peaks at k = lp where l is an integer. essentially, ( )0r gives the largest value among ( )kr , k= lp, for l=0, 1, 2…. the second value is given by ( )pr . other ( )kr peaks of usually decrease as k increases [6] for signals containing a single frequency component. 2) implementation the proposed algorithm uses the autocorrelation function to compute the emg signal spectrum. the maximum power frequencies region of the emg signal is to be from 20 hz to 150 hz, which corresponds to the region (6.67 to 50) msec of the autocorrelation function. since, the sampling frequency of the input emg signal is 2000hz and each truncated window is of 256 samples, then that time region that is represented is between the samples 14 and 100 of the acf. thus, each peak in this region is estimation to a frequency contained in the input emg signal. the bold region illustrated in fig (6) represents the above interested region of the acf of the 14th window of the pectoralis emg signal. it is quite clear that all the major and minor peaks of the acf represent estimation of the corresponding frequencies. the frequency is the reciprocal of multiplying the peak location by the sampling time. for example, the peak at location 98, as illustrated in fig (6), is estimation to: f(98)= 1/(98*500µsec)=20.4081 hz this represents the detected muap of mu. so that, the autocorrelation maxima between these two locations represent the frequency components of the emg signal. fig. 6. the interested search region. 5. results and discussion we applied the autocorrelation method to compute the frequency spectrum of the tested emg signals that sampled by 2000 hz (500 μsec.). as described previously the maximum power frequencies of emg signals will be appear in the region from sample 14 to sample 100 of the acf. figures 7, 8, and 9, illustrate the estimated frequency spectrum of each window of the total 14 windows contained in the pictoralis, biceps, and triceps muscles respectively. mohannad k. sabir al-khwarizmi engineering journal, vol. 9, no.3, p.p. 39-46 (2013) 43 fig. 7. frequency spectrum of each window of the pectoralis emg signal. fig. 8. frequency spectrum of each window of the biceps emg signal. fig . 9. frequency spectrum of each window of the triceps emg signal. mohannad k. sabir al-khwarizmi engineering journal, vol. 9, no.3, p.p. 39-46 (2013) 44 the resolution of the frequency spectrum using acf is not linear as illustrated in fig. (10). it is quite clear from this figure that at low frequencies (samples 90-100) we will get a frequency accuracy of less than 2 hz, which mean a very good resolution, as mentioned previously that almost the mus have a low frequency values. fig. 10. acf frequency resolution verses sample’s location. this resolution is about 0.2 hz which allows us to get more details about the corresponding mus. while the frequency resolution, for high frequency band (samples 14-20), is between 8.3 to 11 hz, which gives less details about the corresponding mus. however, it seems that this low frequency resolution is quite enough for the high frequency band, since the emg signal contains less number of motors having frequencies between 100 hz to 150 hz. the proposed autocorrelation method of emg spectrum analysis may introduce false peaks at the multiples of the period. these peaks will be considered as estimation to a frequency while it is either the second or the third multiple of the preestimated one. to overcome this drawback, tetsuya [6] proposed a weighted autocorrelation approach to improve the extracted pitch accuracy. where, the autocorrelation function is weighted by the inverse of the average magnitude difference function (amdf). the amdf is described by [6]: ψ(k)= ∑ | ( ) + )| …(5) the amdf has the characteristic that when x(n) is similar with x(n+k), ψ(k) becomes small. thus, if x(n) has a period of p, ψ(k) produces a deep notch at k= p. figure (11) illustrates the amdf of the same window shown in figure (6). fig. 11. the amdf of the same window illustrated in fig.(6). as illustrated in fig (11) that amdf has minimum peaks at the same samples of the maximum peaks of the acf illustrated in fig (6). the weighted acf is given by [6]: η(k)=r(k)/ (ψ(k)+m) …(6) where, m is a fixed number (m>0). this weighted acf is applied to all the windows of the pictoralis, biceps, and triceps muscles. figure (12) illustrates the weighted acf of the same window shown in figure (6). fig. 12. the weighted acf for the same window illustrated in fig (6). mohannad k. sabir al-khwarizmi engineering journal, vol. 9, no.3, p.p. 39-46 (2013) 45 fig. 13. the weighted acf & acf of the same window. figure (13) illustrates that the shape of the weighted acf does not differ from that of the nonweighted acf. thus, one can conclude that all the maxima of the acf are estimation to the fundamental frequencies, and are not to any of their harmonics. this is also true for all other windows of the same muscle and the other muscles too. 6. conclusions since the emg signals are non-stationary, so they need a time frequency analysis to characterize the distributions of muaps of different mus. correlation based processing is known to be comparatively robust against noise. the autocorrelation function method, is classified into this category, and may be one which provides the best performance in noisy environments. thus; autocorrelation spectral analysis is applied to short period hamming windowed emg signals of different muscles. the proposed method of spectral analysis of emg signals using autocorrelation function (acf), gives a good estimation of frequency components for non stationary signals such as emg. moreover, its nonlinear frequency resolution property (having high frequency resolution at low frequency band) is quite convenient for emg signal, since more mus have low frequency values, thus requiring high frequency resolution at this frequency band (20hz-50hz), to distinguish more mus of the emg signal. a weighted acf is also applied to reduce the effects of harmonic peaks that may occur at the acf. although the tested emg signals are few, the results are optimistic, and more investigation is recommended. 7. references [1] motion lab system, inc., "a software user guide for emg graphing and emg analysis", 2009. [2] jessica zarndt, "the muscle physiology of electromyography", http://www.holycross.edu/departments/biol ogy/kprestwi/phys'02/labs/emg_lab. [3] m.b.i. raez, m.s. hussain, and f. mohdyasin, " techniques of emg signal analysis: detection, processing, classification and applications", faculty of engineering, multimedia university. 63100 cyberjaya, selangor. malaysia. 2006. [4] roerto merletti and philips a. parker, "electromyography physiology, engineering and noninvasive applications",2004. [5] steven w. smith, "the scientist and engineer's guide to digital signal processing", 2009. [6] tetsuya shimamura, hajime kobayashi, "weighted autocorrelation for pitch extraction of noisy speech", ieee transaction on speech and audio processing, vol.9, no.7, october 2001. [7] bioresearch inc. [8] http://www.bmes642:emg analysis. http://www.holycross.edu/departments/biol http://www.bmes642:emg )2013( 39-46 ، صفحة1دد، الع9 مجلة الخوارزمي الھندسیة المجلد ابر مھند كاظم ص 46 تحلیل الطیف الترددي إلشارة تخطیط العضالت باستخدام دالة التطابق الذاتي **نور كمال محسن *مھند كاظم صابر جامعة بغداد/ كلیة الھندسة الخوارزمي/ تيقسم ھندسة الطب الحیا**،* mohannad3151962@gmail.com *االلكتروني البرید: noorbmemsc81@yahoo.com **االلكتروني البرید: الخالصة emgتحلیإلشارة . و ذلك یؤدي إلى فھم استراتیجیات التحكم في العضالت والحاالت المرضیة. اللبنات األساسیة للنظام العصبي العضلي muتعتبر . العضلي أو السطحيmuلھا الدور في الكشف عن نمط التداخل مع ) muaps(ھي عملیة تحدید وتصنیف ، كما ان وحدة العمل و اإلمكانات الحركیة وقد تم تطویر العدید من التقنیات لتتحلل اشارات الكشف . لفھم القضایا األساسیة ، والفسیولوجیة emgت تقنیات معالجة اإلشارات في التحلل إشارة واستخدم emgات إشارات و إیجاد الطیف الترددي إلى مكون) acf(ھذا البحث تدارس في تطبیق دالة التطابق الذاتي . عضلیا مع درجات مختلفة من التشغیل اآللي ، وبالتالي )stfft(فقد وجد أن استخدام الطریقة المقترحة یعطي القرار لطریقة التردد بانھا جیدة جدا بالمقارنة مع ما ھو ناتج عن استخدام . و تكرارھا .muیمكن تمییز أكثر من mailto:mohannad3151962@gmail.com mailto:noorbmemsc81@yahoo.com design and implementation of network firewall deah j.kadhim /al-khwarizmi engineering journal, vol.2, no. 1,pp 52-69 (2006) 52 al-khwarizmi engineering journal al-khwarizmi engineering journal, vol.2, no.1,pp 52-69, (2006) design and implementation of a proposal network firewall deah j.kadhim walid k.hussain electrical engineering department baghdad college for economic sciences college of engineering/ university of baghdad (received 25 september 2005; accepted 4 april 2006) abstract: in today's world, most business, regardless of size, believe that access to internet is imperative if they are going to complete effectively. yet connecting a private computer (or a network) to the internet can expose critical or confidential data to malicious attack from anywhere in the world since unprotected connections to the internet (or any network topology) leaves the user computer vulnerable to hacker attacks and other internet threats. therefore, to provide high degree of protection to the network and network's user, firewall need to be used. firewall provides a barrier between the user computer and the internet (i.e. it prevents unauthorized internet users from accessing private computers and networks connected to the internet). this paper concerned with the design and implementation of a proposal firewall system which is used to protect both individual computers and corporate networks from hostile intrusion coming through internet. the dual-homed host architecture has been used to implement the proposed firewall system. the designed system is constructed using visual basic 6.0 language. finally, this proposed system is built depending on the packet filtering mechanism to regulate all the packets entering and leaving the protected site using ip address and port number of the tcp packet. also this system deals with application level and monitors all packet data (content) and maintains the firewall activity with internet connection. keywords: computer network, network security and firewall 1. introduction the firewall imposes restrictions on packets entering or leaving the private network. all traffic from inside to outside, and vice versa, must pass through the firewall, but only authorized traffic will be allowed to pass. packets are not allowed through unless they conform to a filtering specification, or unless there is negotiation involving some sort of authentication. the firewall itself must be immune to penetration [1]. firewalls create checkpoints (or choke points) between an internal private network and an untrusted internet. once the choke points have been clearly established, the device can monitor, filter and verify all inbound and outbound traffic. the firewall may filter on the basis of ip source and deah j.kadhim /al-khwarizmi engineering journal, vol.2, no. 1,pp 52-69 (2006) 53 destination addresses and tcp port number. firewalls may block packets from the internet side that claim a source address of a system on the intranet, or they may require the use of an access negotiation and encapsulation protocol like socks to gain access to the intranet [2]. the means by which access is controlled relate to using network layer or transport layer criteria such as ip subnet or tcp port number, but there is no reason that this must always be so. a growing number of firewalls control access at the application layer, using user identification as the criterion. in addition, firewalls for atm networks may control access based on the data link layer criteria. the firewall also enforces logging, and provides alarm capacities as well. by placing logging services at firewalls, security administrators can monitor all access to and from the internet. good logging strategies are one of the most effective tools for proper network security. firewalls may block telnet or rlogin connections from the internet to the intranet. they also block smtp and ftp connections to the internet from internal systems not authorized to send e-mail or to move files. the firewall provides protection from various kinds of ip spoofing and routing attacks. it can also serve as the platform for ipsec. using the tunnel mode capability, the firewall can be used to implement virtual private networks (vpns). a vpn encapsulates all the encrypted data within an ip packet. in general, a firewall is placed between the internal trusted network and the external untrusted network. the firewall acts as a choke point that monitors and rejects application-level network traffic (as shown in figure 1.1). firewalls also can operate at the network and transport layers, in which case they examine the ip and tcp headers of incoming and outgoing packets, and reject or pass packets based on the programmed packet filter rules [1]. 2. firewall objective all traffic from inside to outside, and vice versa through the main entry, must pass through the firewall. this is achieved by physically blocking all access to the site except via the firewall. various configurations are possible. only authorized traffic, as defined by the local policy, will be allowed to pass. various types of firewalls are used, which implement various types of security policies [3]. in general firewall is one of the famous types of intruder detection [4]. figure 1: firewall operation deah j.kadhim /al-khwarizmi engineering journal, vol.2, no. 1,pp 52-69 (2006) 54 firewall effective against worms because it is much difficult for a worm to authenticate itself to a firewall operating a tight exclusive policy than to a general, widely used system. it is effective against trojan horse. however, even firewall is not invincible [5]. 3. firewall conditions there are some conditions must be considered in the firewalls, the most important conditions are declared in the following points [6]:  the firewall must be easy to use, has powerful graphical user interface (gui), which simplifies the job of installation, configuration, and management.  the firewall must be high performance, should be fast enough so users do not feel the screening packets. the volume of data throughput and transmission speed associated with the product should be consistent with the company's bandwidth to the internet.  the firewall must be flexible, should be opened enough to accommodate the security policy of the company, as well as to allow for changes in the features. remember that a security policy should a very seldom change, but security procedures should always be reviewed, especially in light of new internet and web centric application. 4. firewall limitations security of firewalls neither provides perfect security nor it free from operational difficulties. the most important limitations of the firewall are interpreted in the following points [7]:  firewalls do not protect against malicious insiders.  firewalls have no protections against connections that circumvent the firewall (i.e. modems) attached to computer inside the firewall.  firewalls can not protect against the transfer of virus-infected programs or files. because of the variety of operating systems and applications supported inside the perimeter, it would be impractical and perhaps impossible for the firewall to scan all incoming files, e-mail, and message for viruses.  firewalls can not protect against completely new threats, firewalls designed to protect against known threats. no firewall can automatically defend against every new threat arises. 5. firewalls favorites control positions a firewall system can be a router, a personal computer, a host, or a collection of hosts, set up specifically to shield a site or subnet from protocols and services that can be abused from hosts outside the subnet. a firewall serves as the gatekeeper to centralized access control between the untrusted internet and trusted internal network [8]. so due to a firewall behavior, it can be at any of the following levels:  between an internal network and internet. for example a firewall can be implemented on the main server of a country to enforce any security policy to restrict any restricted web sites and monitoring e-mail messages coming in and going out.  between subnets inside an internal networks. for example a connection between two organizations related with the same ministry, they are transmitting information between them but each organization enforce its security policy which can be implemented by using a firewall.  between a single pc and computers on the same networks or other networks on the internet. for example if we have deah j.kadhim /al-khwarizmi engineering journal, vol.2, no. 1,pp 52-69 (2006) 55 some one wants to isolate his pc from any where, one way to secure his pc is by using a firewall. 6. types of firewalls [1] there are many types of firewall, they tend to differ in their approach but can be characterized as firewalls, which block traffic, and firewall which permit traffic. then each one of them differ than the other in behaves but they are all share the same point that they do as a shield to protect the private network users. these types are described and explained with its configurations and its advantages vs. disadvantages in details in above reference and it can here list them as follows:  packet filtering firewall  circuit level firewall  application layer firewall  dynamic packet filter firewall the proposed system is built depending on the packet filtering mechanism to regulate all the packets entering and leaving the protected site using ip address and port number of the tcp packet. also this system deals with application level and monitors all packet data (content) and maintains the firewall activity with internet connection. 7. firewall architecture (configuration) [1] firewalls are configured in different ways, depending on how your company decides to balance the cost versus security. the most secure firewalls often use combination of security layers to offer the most protection. there are three types of basic firewall configurations (architectures) in use today. they are:  dual homed host architecture  screened-host architecture  screened-subnet architecture each configuration has a different tradeoff among between security, cost, and performance. for example, dual homed firewalls are easier to configure and set up than screened hosts, but at a slight loss in security. the dual-homed host architecture has been used to implement the proposed firewall system. 8. proposed firewall system the following sections will give the design and software implementation processes of the proposed firewall system and show all the main points that used in design and software implementation processes. the proposed system contains packet filtering mechanism and application level monitor. the first part of firewall is constructed using packet filtering mechanism by applying the single box architecture (dual-homed host) because this architecture provides the best isolate between internet and protected network. the packet filtering is used because it is the basic rule to construct all types of firewall mechanisms are using the packets in it work. the second part of firewall uses other security mechanisms like log file, authentication and auditing to the user. this part is used to identify the manager or employee and to display the private information that specified to manager or employee. the proposed firewall system works by receiving packet from the first lan card that connects to the internet and from the ports that the system scans it. then it sends the packet to a buffer, the system will be examining each packet in the buffer by compare the ip address of the source computer and destination computer of packet with authorized ips table. therefore, the number of ports and the ip of source and destination computer determine the level of security. whereas the ip of the source or destination computer is unauthorized the packet is rejected, access is denied and sends message to the request owner (source computer) about this situation. when the ip of deah j.kadhim /al-khwarizmi engineering journal, vol.2, no. 1,pp 52-69 (2006) 56 the source and destination address is authorized, the firewall system will ask the user about his name and password to login inside the protected network. if the name and password is not true the firewall system will reject his request until the user enter the true name and password or cut the connection. but when the user enters the true name and password, the firewall system sends the packet to the second lan card connected to the protected network. the flowcharts of figures (2) and (3) represent the mechanism of the proposed firewall system. the proposed firewall system uses many algorithms to complete his work; the following sections will provide the outline of these algorithms: 9. send/received packet from lan card the following algorithm is used when received packet from lan card, this algorithm explains the operation of send packet after check the ip address and port number. the firewall program will check the ip's and ports that come from a packet. if the received packet comes from an authorized ip and port is authorized, then allow packet to transfer normally if it is unauthorized then block the connection. send/received packet from lan card input: packets output: scan packet for passing. step 1: get packet from lan card. step 2: store incoming packet in a buffer. step 3: check the ip address and port number of the sender. step 4: check the ip address and port number of the receiver. step 5: if the ip address and port number are authorized, then allow packet to send/receive else block the connection step 6: end deah j.kadhim /al-khwarizmi engineering journal, vol.2, no. 1,pp 52-69 (2006) 57 user in the internet first lan card connects to the internet received packet from source computer received packet from specified port authorized ip? authorized user? send packet to the second lan card connected to the protected network second lan card sends packet to the destination computer in protected network user in protected network rejected packet and access is denied send message to the user no yes no yes figure (2): incoming packets to the firewall system from the internet deah j.kadhim /al-khwarizmi engineering journal, vol.2, no. 1,pp 52-69 (2006) 58 user in protected network second lan card connects to the protected network received packet from source computer received packet from specified port authorized ip? authorized user? send packet to the first lan card that is connected to the internet first lan card sends packet to the destination computer in the internet user in the internet rejected packet and access is denied send message to the user no yes no yes figure (3): incoming packets to the firewall system from protected network deah j.kadhim /al-khwarizmi engineering journal, vol.2, no. 1,pp 52-69 (2006) 59 8.1 check/add ip address the following algorithm is used to check the ip address for database when the administrator of the proposed firewall system insert ip address, examine the database if it is found or not. the first step in this algorithm is used if the administrator adds new ip address to the database. the second step check if this ip address found in the database, if found then message "ip is found" will be displayed, if not then store ip address in the database. check ip address input: ip address output: scan ip address. step 1: get ip address from administrator. step 2: search the ip value in database, if found. then display message "ip address is found" else store the ip address in database step 3: end remove ip address this algorithm explains how to delete ip address from the database, the program will open database that contains all the ips, the administrator will choose the ip of specified computer and removed it. this program has the same function of remove the address of this specified computer (i.e. the real address web page address in the internet of this specified computer). remove ip address input: ip address output: ip address remove from database. step 1: get ip address from field of deny access from/to ip's. step 2: search in database for ip, if found then delete the ip address else display message "ip not found" step 3: end 8.2 check/add port number this algorithm is used to check port number for database when the administrator of the proposed firewall system insert port number, examine the database if it is found or not. the first step is used if the administrator adds new port number to the database. the second step check if this port number is found in the database, if found then message appear the "port is found" of if not then store port number in the database. check port number input: port number output: scan port number. step 1: get port number from administrator. step 2: search the port number value in database, if found then display message "the port number is found" else store the port number in database step 3: end 8.3 remove port number this algorithm is used to show how to delete port number from database, the algorithm will open database that contains all port numbers, and the administrator will choose the ort number of specified computer and removed it. remove port number input: port number output: port number removed from database. step 1: get port number from field of deny access from/to ports. step 2: search in database for ports, if found then delete port number else display message "port not found" step 3: end 8.4 check/add address and port number this algorithm is used to check the ip address and port number for database when the administrator of the proposed firewall system insert ip address and port number, examine the database if it is found or not. the first step is deah j.kadhim /al-khwarizmi engineering journal, vol.2, no. 1,pp 52-69 (2006) 60 used, if the administrator adds new ip address and port number to the database. the second step check if this ip address and port number found in database, if found then message appear the ip and port number are found or if not then store ip address and port number in the database. check/add address and port number input: ip address and port number. output: scan ip address and port number. step 1: get ip address and port number from administrator. step 2: search the ip and port value in database, if found then display message "the ip address and port number are found" else store the ip address and port number in database step 3: end 8.5 remove ip address and port number this algorithm is used to show how to delete ip address and port number from the database. remove ip address and port number input: ip address and port number. output: ip address and port number are removed from database. step 1: get ip address and port number from field of deny access. step 2: search in database for the ip and port number, if found then delete the ip address and port number else display message "ip and port number are not found" step 3: end 8.6 block ip address and port number this algorithm is used to block (cannot open) any specified ip address or port number. the blocking process is done using by either ip address or port number. blocking addresses does not always work. some web sites have multiple servers baking up the primary site. if connection to the first server does not work then it will be routed to the second server and so on. to successfully block an address that need to know all the ip addresses that are registered to the primary web address. block ip address and port number input: ip address or port number. output: ip address and port number are blocked. step 1: edit ip address or port number from field of deny access. step 2: search for ip address or port number that is edited, if found the unload this ip address or port number else display message "the ip address and port number are found" step 3: end 8.7 try to connect address and send text this algorithm is used to try connecting to address in order to show data viewer. this algorithm used network winsock object to connect and get data through network. trying to connect is limited through timer and gives specified time to try connecting. after the connection is established, then it can send any text to this address, note that the emulation taking any chosen operating system like windows-95, windows-98, windows-2000, and windows-xp. and finally it can also disconnect this connection through enabling the administrator this feature by its opinion. deah j.kadhim /al-khwarizmi engineering journal, vol.2, no. 1,pp 52-69 (2006) 61 try to connect to address input: physical address or ip address. output: connected to physical address or ip address. step 1: get ip address or address from administrator. step 2: if received request then check the socket is not busy step 3: if socket is busy then send wait to user else accepted request step 4: send "identify" command to user request connection step 5: end 9. software implementation of the proposal firewall system this section presents the software implementation of the proposed firewall system that had been built from algorithms discussed in previous sections. like any firewall system, the proposed firewall system consists from many parts, this section presents and explains the works of proposed firewall system's windows and the relationship between these windows. the proposed firewall system contains more than one window to display the parts of the system; the following sections will describe these parts with its job in firewall system work. 9.1 the main window of firewall system figure (4) shows the main window of proposed firewall system, that displays the public parts of this system. this main form of the network firewall program, which has a screen monitoring of all the connections associated with the computer that this program is working on , and also have a filter screen that represents the filter contents preventing any incoming packets by blocking three types of locations (address , local port and remote port) . figure (4): the main window of proposed firewall system deah j.kadhim /al-khwarizmi engineering journal, vol.2, no. 1,pp 52-69 (2006) 62 9.2 enabling packets filtering it can start work this proposed firewall system by adding some addresses (preferred ip addresses) or it can add a remote port or local port, it can retrieve the information about these setting from the listening screen. note that the filter can be enabled and disabled by clicking on enable, disable filter button on the right of the main window as shown in figure (5). so public address or ip address, local port and remote port can be added to filter them from accessing through the internet. 9.3 log view file window this file is used to enable the administrator to show all information about each connection established when the proposed firewall system is running. when button "view log" is pressed, the system will display the content of log file as shown in figure (6), and then the details of all connection can be shown with time and date. so it can say that this file displays the status of the firewall system and on line status of the connection over the firewall system. figure (5): enabling or disabling packets filtering deah j.kadhim /al-khwarizmi engineering journal, vol.2, no. 1,pp 52-69 (2006) 63 9.4 blocking and connection functions the power of this program is presented by right clicking on any connection, then it see in the listening screen (main program window); then you will see three options: 1. block: just for blocking the connection but not ending it. 2. connect: for trying to connect to this connection and deal with it. 3. end the connection. figure (7) shows these three options. figure (6): view log file window deah j.kadhim /al-khwarizmi engineering journal, vol.2, no. 1,pp 52-69 (2006) 64 9.5 blocking function window this window is used to block (cannot open) any specified ip address or port number. the blocking process is done using by either ip address or remote port number or local port number. figure (8) shows how this operation is done by clicking on (block) the form block will appeare conaining three options , by address or by remote port or by local port, click (block) to block the desired option or click (cancel) to unload the form and return to the main form. to successfully block an address you need to know all the ip addresses that are registered to the primary web address. figure (7): blocking and connection functions deah j.kadhim /al-khwarizmi engineering journal, vol.2, no. 1,pp 52-69 (2006) 65 9.6 connection function window this window is used to try connecting to address in order to show data viewer. trying to connect is limited through timer and gives specified time to try connecting. after the connection is established, then it can send any text to this address. finally it can also disconnect this connection through enabling the administrator this feature by its opinion. figure (9) shows how this function is operated by clicking on (try to connect), the form (test connection) will appear containing the address or the address that want to connect to, and when it choose the (connect to) part of the form will be enabled asking about the text that want to send to that connection. it can verify the type of emulation by enabling it and choosing any type of windows that is wanted. figure (8): blocking function deah j.kadhim /al-khwarizmi engineering journal, vol.2, no. 1,pp 52-69 (2006) 66 9.7 error windows there are error labels in this program and one of them can be shown in figure (10), this error label is caused by trying to end a connection without a connection to a remote port. figure (9): connection function deah j.kadhim /al-khwarizmi engineering journal, vol.2, no. 1,pp 52-69 (2006) 67 10. conclusions many conclusions can be noticed in this paper, they are:  the proposed firewall system can be used to protect one computer (personal computer pc) from the attacker when connecting to a lan and also can be used to protect many computers that connected together in lan from the outside attack in the internet.  from functional point view, the proposed system can be used in two ways: first as security tool, where the system prevents the hacker from entering the protected computer or network. second as monitoring tool which can be used in many applications by using ip address and port number.  all types of firewall depend on packet capture processing. when we need to build any type of firewall, we must process the packet of connection to make firewall work in the right place. for this reason, this research depends on packet filtering firewall.  using dual-homed host architecture helped us in increasing the protection because it isolate the protected network from the internet and all traffic must pass though this host. figure (10): one of errors windows deah j.kadhim /al-khwarizmi engineering journal, vol.2, no. 1,pp 52-69 (2006) 68  there are basic firewall types, but they can typically be grouped into (packet filtering, application level, and circuit level) with each approach having strength. however, all firewalls share a common attribute, either allowing or deny access to the packet coming from internet. 11. references [1] e. zwiky, s. copper, and d. chapman, "building internet firewalls", second edition, o'relly & association, 2000. [2] j. bryan lyles & christoph l. schuba, "a reference model for firewall technology and its implications for connection signaling", 1996. [3] kent p., "10 minute guide to the internet", prentice-hall of india, 1998. [4] kent p., "the complete idiot's guide to the internet", second edition, que, adivision of macmillan computer publishing, 1994. [5] crumlish c., "the abcs of the internet", sybex inc., usa, 1996. [6] escamilla t., "intrusion detection network security beyond the firewall", john wiley & sons inc., 1998. [7] stallings w., "high-speed networks: tcp/ip and atm design principle", prentice-hall inc., 1998. [8] k. parner & n. cowchan duncan, "an introduction to security", security manual, canada, 1999. deah j.kadhim /al-khwarizmi engineering journal, vol.2, no. 1,pp 52-69 (2006) 69 ضياء جاسم كاظم وليد خالد حسين كلية بغداد للعلوم االقتصادية جامعة بغداد –كلية الهندسة الخالصة: نتيجة التطور و النمو السريع في شبكات المعلومات و االنترنيت نظرا ألهمية االنترنيت في عالم اليوم لما يوفره من خدمات الفوائد وغيرها ممكن ان تنقلب للمستخدمين من سهولة الحصول على المعلومات المختلفة بسرعة عالية وبأقل جهد ممكن , كل هذه ( باألنترنيت يفتح المجال امام lan( او الشبكات المحلية )private computerالى مضار خطيرة , اذ ان ارتباط الحاسبة الخاصة ) ( الذين يحاولون بطريقة ما ايجاد اي نقطة ضعف او منفذ للدخول عبر intruders( والدخالء )hackersهجمات القراصنة ) نترنيت الى هذه الحاسبات الغرا التجس او لسرقة معلومات )كالتالعب بالحاسبات المصرفية او معرفة كلمة سر وغيرها( او في اال بع االحيان الغرا التخريب لي اال . لذلك اصبح من المهم جدا ايجاد طريقة لحماية الشبكات ومستخدميها من مثل هذه التهديدات (.firewallطرق الحماية التي توفر درجة عالية من االمنية هي استخدام جدار النار ) . واحدة من اهم privateيستخدم لحماية الحاسبات الخاصة )مفتر (firewallيهدف هذا البحث الى تصميم وتنفيذ جدار ناري ) computer( والشبكات المحلية )lanمعمارية الموطن المضيف المزدوج ( من االعداء المتطفلين خالل االنترنت.تم أستخدام (dual-homed host في تصميم نظام الجدار الناري المقترح. النظام المقترح تم بناءه بأستخدام لغة الفيجول بيسك )6. باالعتماد على استخدام ميكانيكية مرشح الحزم لتنظيم دخول وخروج جميع الحزم للموقع المفتر أخيراً تم بناء هذا النظام (. وكذلك يتعامل هذا النظام مع مستوى التطبيق port number( ورقم البوابة )ipحمي وذلك باستخدام عنوان االنترنت برتوكول )الم (application level.لمرقبة جميع محتوى حزم البيانات الداخلة من خالل تفعيل دور الجدار الناري عند االتصال باالنترنت ) احمد جواد al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 5869 (2013) simulation of a wet sulfuric acid process (wsa) for utilization of acid gas separated from omani natural gas ahmed jawad ali al-dallal department of chemical engineering / college of engineering / university of sahaar (received 2 april 2013; accepted 6 october 2013) abstract in this study, a proposed process for the utilization of hydrogen sulphide separated with other gases from omani natural gas for the production of sulphuric acid by wet sulphuric acid process (wsa) was studied. the processwas simulated at an acid gas feed flow of 5000 m3/hr using aspen onev7.1-hysys software. a sensitivity analysis was conducted to determine the optimum conditions for the operation of plant. this included primarily the threepacked bed reactors connected in series for the production of sulphur trioxidewhich represented the bottleneck of the process. the optimum feed temperature and catalyst bed volume for each reactor were estimated and then used in the simulation of the whole process for two cases namely 4 and 6 mole% so2 stream fed to the first catalytic reactor. the 4mole% so2 gaves the highest conversion (98%) compared with 6 mole% so2 (94.7%). a valuable quantity of heat was generated from the process. this excess heat could also be transformed into power in a turbine or used as a heating media in neighbouring process units. keywords: simulation, acid gases, wsa, sulphuric acid production. 1. introduction most of natural gases contain h2s as a major impurity. h2s isa highly toxic and corrosive gas and considered as one of the majorsources for the environmental problems such as acid rains. therefore, in order to utilize these fuels for chemical processing or energygeneration, the h2s concentration in these gases must be reducedto very low levels [1]. acid gas removal process is a very important industrial operation, which has been described elsewhere. the main processes used are based on absorption, and the selectivity of the solvent with respect to acid gasses is based on an affinity of the chemical or physical type. adsorption is also used for intensive purification. gas permeation has a substantial potential, but today, industrial applications are limited. the different processes for separation of acid gases from natural gas is well represented by zulkifli[2]. numerous different methods exist for the treatment of gaseous effluents that containboth acid compounds h2s and co2.the selection of an optimum method for theelimination is not easy and, in many cases, to obtain the degree of purification of gas desired, it is necessary to combine different processes. for the evaluation of the methods of utilization, the following variables, amongothers, must be taken into account [3]: concentration of h2s in the gas to be utilized. pressure, temperature and composition of the gas. ratio of h2s to co2. volume of gas to be processed. total h2s load off-gas specifications for the process output. economic considerations. environmental implications. the acid gas after separation from omani natural gas contains hydrogen sulfide, carbon ahmed jawad ali al-dallal al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 5869 (2013) 59 dioxide, water vapor and small quantity of methane [4]. the aim of this study is to perform a case study on the application of the wsa process for the utilization of h2s in the acid gas to produce sulfuric acid using wet sulfuric acid process (wsa) and to determine the optimum conditions for this process. 2. the wsa process the wsa (wet gas sulphuric acid) processis an effective and in some cases superior alternative to the claus process for the production of sulphur from sulphur containing gases[1].it is a process for the conversion of sulphurous streams into sulphuric acid developed by haldor topsøe a/s, denmark. since its introduction in the 1980s, the wsa process were recognised as an efficient process for recovering sulphur from various sources in the form of commercial quality sulphuric acid. the wsa process is a catalytic process producing 93–98 wt% acid [5].up to 2009, topsøe wsa plants have been in operation foralmost 30 years, and close to 80 plants were sold[6]. it has found widespread application in the metallurgical, steel industry (coking plant), power and cellulose industry, but the majority of applications are within the refinery and petrochemical industry[7]. in spite of its unique features andability to treat gases without any prior drying, the wsa technology has had certainrestrictions with regards to so2 concentration in the feed gas, and the overall conversionof so2 by catalytic means has been limited to approximately 99.7%.the wsa process is applied in all industries where the removal of sulphur is an issue.typical applications include [5-8]: h2s-containing gases from amine units. sour water stripper gases. regeneration of spent sulphuric acid from alkylation. treatment of stack gases from boilers fired by heavy residues and petroleum coke. in the viscose fibre industry for treatment of hydrogensulphide and carbon disulphide containing off-gases. in the non-ferrous metallurgical industry for treatmentof so2 containing off-gases from a variety of process units. there are many advantages why one should use the wsa process for acid-gas treatment. the process does not generate any waste products or waste water and does not use any absorbents. firstly the process produces sulfuric acid, which is a more valuable compound in comparison to elemental sulfur. secondly the process uses the water content in the process gas and air introduced, which enables production of high purity concentrated sulfuric acid. the block diagram for the wsa process is shown in figure 1. fig. 1. a block diagram of the various steps in the wsa process. ahmed jawad ali al-dallal al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 5869 (2013) 60 the inlets sulphurous gases are fed to a combustor where they are mixed with combustion air. in the combustor the hydrogen sulphide isconverted to sulphur dioxide according to thefollowing exothermic reaction[9]: h2s + 3/2 o2 → h2o + so2 ...(1) in case there is some methane in the acid gas (as in our case), it will be combusted according to the following reaction: ch4 +2o2→ co2 + 2h2o ...(2) the process gas leaving the combustor iscooled in a waste heat boiler. the cooledso2 containing gas is fed to the so2 converterwhere it is converted to so3 in three adiabaticcatalytic beds. in the converter the so2 isoxidized to so3 according to the following reaction: so2 + 1/2 o2 ↔ so3 ...(3) the reaction is a temperature and pressuredependent equilibrium reaction. in order toachieve a high conversion the reaction is cooledin two inter-beds[8]. after the third catalyst bed theprocess gas is cooled by boiler water. during thiscooling part of the formed so3 reacts with thewater vapour present in the process gasaccording to the following exothermic hydrationreaction: so3 (g) + h2o (g) → h2so4 (g) ...(4) being a single-contact process, the so2/so3 equilibrium curve limits the conversion totypically 99.4 99.7%[6]. this limitation can be overcome by scrubbing the tail gas withcaustic or hydrogen peroxide, but this means additional investment and operatingcosts. after the so2 converter the process gas is fed tothe wsa condenser were it is cooled by ambientair. during the cooling the remaining hydrationreaction and condensation of the sulphuric acidtakes place: h2so4 (g) → h2so4 (l) ...(5) the condensed hot sulphuric acid is furthercooled in a heat exchanger cooled by coolingwater. the acid is of commercial quality. theclean process gas leaves the condenser at the top.the heat released by all the exothermic reactions in the wsa plant is recovered in the form of steam. because of considerations concerning construction materials in the wsa condenser,is not possible to handle gases with sulphuric acid dew points higher than around260°c[6]. this corresponds to a content of so2 inlet to the so2 converter of some 6 – 7vol%. this limitation of course can be overcome by dilution of the gas withatmospheric air, but this will increase the process gas volume and thereby thedimensions of the plant. 3. simulation of wsa process wsa process is simulated with aspenone7.1-engineering (hysys) using the actual composition of theacid gas produced after separation from omani natural gas [4] as shown in table 1: table 1, feed acid gas composition. component composition mole% h2s 16.7 co2 73.0 ch4 0.20 h2o 10.1 although some authors refer to the h2s acid gas separated from natural gas by amine process but actually there is no data available in literature about this application. in any case, all the required operating data necessary to complete the simulation are collected from different sources [6,9,10].the air introduced to the process is assumed to be at 40 oc and with 70% relative humidity according to omanclimate. the most important part of this process is the so2 oxidation reactors. there are commercially three reactors in series. each reactor is occupied by different quantity of catalyst. the so2 oxidation catalyst is based on a silica carrier (diatomeous earth) impregnated with a mixture of sodium, potassium and vanadium [10].the vkwsa catalysts are specially developed for use in humid process gases [6]. the top layer of catalyst in the first bed consists of 25 mm daisy shaped particles which provide good capacity for accumulation of dust without creating excessive pressure drop. the remaining catalyst consists of either 9 mm or 12 mm daisies. due to the exothermal reaction, the outlet temperature from the first bed may reach around 600°c. the gas is cooled by superheating of high pressure steam ahmed jawad ali al-dallal al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 5869 (2013) 61 and the gas flows to the second bed. after the second bed the gas is cooled again by superheating of high pressure steam and the conversion is continued in the third bed. at the outlet of the third bed the conversion has reached more than 95%. the gas is then cooled to around 300°c by production of high pressure steam, whereby part of the so3 reacts with h2o to form h2so4 vapour. the typical properties of the vk-wsa series catalyst specially manufactured for the wsa process is shown in table 2. [11]: 4. simulation of wsa process wsa process is simulated with aspenone7.1-engineering (hysys) using the actual composition of theacid gas produced after separation from omani natural gas [4] as shown in table 1: table 1, feed acid gas composition. component composition mole% h2s 16.7 co2 73.0 ch4 0.20 h2o 10.1 although there is some authors refer to the h2s acid gas separated from natural gas by amine process but actually there is no data available in literature about this application. in any case, all the required operating data necessary to complete the simulation are collected from different sources[6,9,10].the air introduced to the process is assumed to be at 40 oc and with 70% relative humidity according to omanclimate. the most important part of this process is the so2 oxidation reactors. there are commercially three reactors in series. each reactor is occupied by different quantity of catalyst. the so2 oxidation catalyst is based on a silica carrier (diatomeous earth) impregnated with a mixture of sodium, potassium and vanadium[10].the vkwsa catalysts are specially developed for use in humid process gases [6]. the top layer of catalyst in the first bed consists of 25 mm daisy shaped particles which provide good capacity for accumulation of dust without creating excessive pressure drop. the remaining catalyst consists of either 9 mm or 12 mm daisies. due to the exothermal reaction, the outlet temperature from the first bed may reach around 600°c. the gas is cooled by superheating of high pressure steam and the gas flows to the second bed. after the second bed the gas is cooled again by superheating of high pressure steam and the conversion is continued in the third bed. at the outlet of the third bed the conversion has reached more than 95%. the gas is then cooled to around 300°c by production of high pressure steam, whereby part of the so3 reacts with h2o to form h2so4 vapour. the typical properties of the vk-wsa series catalyst specially manufactured for the wsa process are shown in table 2.[11]: table 2, typical properties of the vk-wsa series catalyst. catalyst vk-wsa description diameter (outer/inner), (mm) length , (mm) 25/9 22-28 12/4 10-14 chemical composition v2o5, (wt%) k, (wt%) na, (wt%) 6 8 7 12 1 2 physical properties bulk density (kg/m3) attrition loss (%) 420-440 4 6 350-370 2 – 4 operating conditions gas concentration, so2 (mole%) minimum o2/so2 (mole/mole) 0 10 0.6 the thermal and electrical behaviour “k-nav” catalyst series for so2 oxidation (produced specially for the wsa process) is studied by guo et al.[12]. there results showed the following reaction kinetics as a function of the partial pressures: ahmed jawad ali al-dallal al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 5869 (2013) 62 )( )1( 322 221 2 32 so m oso m oso so pkpkp appk r ++ − = ...(6) 5.0 22 3 osop so ppk p a = ...(7) )exp( rt eak −= ...(8) 6455.45.4905log −= t kp ...(9) the parameters used in above equations are shown in table 3. table 3, parameters used in the reaction rate equation [12]. many references stated that;the process which leave the last catalyst bed will typically contains so3 plus water vapour[5,7,8]. this means that there are no remarkable reaction between so3 and water vapour during the three catalytic reactors connected in series. after the last conversion stage, the gas is cooled and most of the so3 reacts with water vapour and forms gas phase sulphuric acid and then the process gas goes to the wsa condenser where final hydration and condensation of acid takes place[5]. only almqvist et al. [14] assumed that the reaction which produces vapour sulphuric acid occurrs through the three catalytic packed reactors connected in series. the reaction kinetics for the formation of gaseous sulphuric acid was studied by different authors [15-18] . only jayne et al. [18] studied the effect of temperature on this reaction kinetics and theirwork is represented by the following equations: 3 2 243 soohso cckr =− . ..(10) t)exp(13.5/r 10 x 411k 7.4 = ...(11) where r is in kcal/mole.k and rso3 in cm6/mole.s we try to introduce this kineticsinside the three catalytic packed reactors connected in series used for the oxidation of so2 in the simulation case using equations 10 and 11.we found that we need to increase the volume of reactors ten times to allow the vapour phase sulphuric acid formation to occur in these reactors. in this simulation we assume that all the vapour phase formation of sulphuric acid occurs after the third catalytic packed reactor according to different authors [5,7,8] . after the third reactor the effluent is cooled to 270 oc and then introduced to the condenser which represented in the simulation by a conversion reactor where we assumed that all so3 will convert to h2so4. in this simulation we try to apply two different concentration of so2 fed to the catalytic packed reactors namely 4 and 6 mole% by regulating the flow of air fed to the system. more than 6 mole% so2 will not be applicable since there is no enough oxygen for oxidation of so2. less than 4% will reduce the temperature in the reactor and reduce the efficiency of the heat utilization. in any case 4-6 mole% so2 was normally used in commercial production of sulfuric acid by wsa process [5,7]. 5. results and discussion the simulation sensitivity results for the effect of input temperatures for the three catalytic reactors on the fractional conversion of so2 are shown in figure 2 and 3 for 4 and 6 mole% so2 respectively. the optimum feed temperature for 4% will be 430, 450 and 430 0c for the three reactors respectively. the optimum feed temperature for 6% will be 430, 460 and 440o crespectively. parameter operating temperature range, oc 380 470 470 580 a1 3.035 x 107 15.63 e1[kj/kmole] 1.69 x 105 7.89 x 104 a2 1.943 x 10-7 1.111 x 10-5 e2 [kj/kmole] -7.21 x 104 5.57 x 104 a3 3.021 x 104 5.019 x 104 e3[kj/kmole] 6.912 x 104 6.897 x 104 m 0.65 0.55 ahmed jawad ali al-dallal al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 5869 (2013) 63 fig. 2. effect of reactor feed temperature on the cumulative fractional conversion of so2 in the three plug flow reactors (pfr’s) connected in series at 4 mole% so2 in feed. fig. 3. effect of reactor feed temperature on the cumulative fractional conversion of so2 in the three plug flow reactors (pfr’s) connected in series at 6 mole% so2 in feed. the effect of reactor volume for the three catalytic reactors on the fractional conversion of so2 were shown in figures 4 and 5 for 4 and 6 mole% so2 respectively. the optimum volumes for 4 mole % so2 is 3.5, 4.5 and 5.5 m3 for the three reactors respectively. the optimum reactorvolumes for 6% is 4.5, 5.5 and 6.5for the three reactors respectively. 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 250 300 350 400 450 500 550 fr ac ti on al c on ve rs io n of s o 2 reactor feed temperature, 0c pfr-1 pfr-2 pfr-3 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 250 300 350 400 450 500 550 fr ac ti on al c on ve rs io n of s o 2 reactor feed temperature, 0c pbr-1 pbr-2 pbr-3 ahmed jawad ali al-dallal al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 5869 (2013) 64 fig. 4. effect of reactor volume on the cumulative fractional conversion of so2 in the three plug flow reactors (pfr’s) connected in series at 4 mole% so2 in feed. fig. 5. effect of reactor volume on the cumulative fractional conversion of so2 in the three plug flow reactors (pfr’s) connected in series at 6 mole% so2 in feed. the mole fraction of different component throughout the first plug flow reactor is shown in figure 5 and 6 for 4 mole% and 6 mole% so2 respectively. 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 0 2 4 6 8 10 12 fr ac ti on al c on ve rs io n of s o 2 reactor volume, m3 pbr-1 pbr-2 pbr-3 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 0 2 4 6 8 10 12 fr ac ti on al c on ve rs io n of s o 2 reactor volume, m3 pbr-1 pbr-2 pbr-2 ahmed jawad ali al-dallal al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 5869 (2013) 65 fig. 6. the distribution of mole fraction of different component throughout the first plug flow reactor (pbr-1) at a feed of 4 mole% so2. fig.7. the distribution of mole fraction of different component throughout the first plug flow reactor (pbr-1) at a feed of 6 mole% so2. the optimum conditions with respect to the volume of reactors and the feed temperature to the reactors were used in the simulation for the two cases (4 mole% and 6 mole% so2).the main results for the two simulation cases are shown in table 4 0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.00 0.20 0.40 0.60 0.80 1.00 m ol e fr ac ti on packed bed reactor height, m o2 so2 h20 so3 0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.00 0.20 0.40 0.60 0.80 1.00 m ol e fr ac ti on packed bed reactor height, m o2 so2 h20 so3 ahmed jawad ali al-dallal al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 5869 (2013) 66 table 4, main results of the process simulation. conversion at discharge from pfr’s total heat generated from the whole process wt% h2so4 production rate of h2so4kg/h pbr-1 pbr-2 pbr-3 4% so2 0.894 0.967 0.980 9.95 x 107kj/h 98.7 3620 6% so2 0.7736 0.9107 0.947 1.084 x 108kj/h 98.0 3527 as shown in table 4, the equilibrium conversions will reach a maximum value that cannot be exceeded even if we increase the volume of catalytic reactor which is the normal case for equilibrium reversible reaction. in general, the equilibrium conversion that can be reached for 4 mole% so2 is relatively higher than 6 mole% so2. the presence of excess oxygen raises the so2 equilibrium conversion as mentioned before, but it is also an essential prerequisite for maintaining the activity of the vanadium catalyst. in any case working with 4 mole% so2 will reduce the treatment efforts for the off-gas produced from this process. haldor topsøe a/s gave guarantee of a maximum of 2 kg so2 emission per ton 100 % sulfuric acid produced for one of the cases studied [14]. actually this value cans hardlyachieved in our case where about 16 kg of so2 is produced per ton 100% sulfuric acid produced. this implied that extra tail gas treatment was necessary in order to achieve desired sulfur dioxide content in the stack gases. the overall process is exothermal and large amount of steam is produced in the heat exchangers, which is used for preheating of the feed gas and for addition of water if that is necessary. the excess heat can also be transformed into power in a turbine or used as a heating media in neighbouring process units[14].no remarkable difference in the heat generated and production capacity and concentration of sulphuric acid for both cases were observed (as shown in table 4). the complete simulation flow sheet for the process using aspen-one-hysys is shown in figure 8. fig. 8. simulation flow sheet for wsa process. ahmed jawad ali al-dallal al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 5869 (2013) 67 6. conclusions the following conclusions can be withdrawn from this study: wet sulphuric acid process (wsa) was used successfully for the production of sulfuric acid by utilization of hydrogen sulphide separated from omani natural gas. a sensitivity analysis was conducted to determine the optimum conditions for the plantoperation. this includes primarily the three packed bed reactors connected in series for the production of sulphur trioxide which represent the bottleneck of the process. the optimum feed temperature and catalyst bed volume for each reactor for production of so3 was found and then impended for the simulation of the whole process for two cases namely 4 and 6 mole% so2 stream fed to the first catalytic reactor. the 4 mole% so2 gives the highest conversion (98%) compared with 6 mole mole% so2 (94.7%). a valuable quantity of heat was generated from the process. this excess heat could also be transformed into power in a turbine or used as a heating media in neighboring process units. symbols a frequency factor ch20 water vapour concentration [mole/cm3]cso3so3 concentration [mole/cm3] e activation energy[kj/kmol] kp rate constant k equilibrium constant[atm–5] m partial pressure exponent p pressure[atm] pso2 partial pressure of so2[atm] po2 partial pressure of o2[atm] pso3 partial pressure of so3[atm] r gas constant [= 8.314 kj/kmol k] rso2 intrinsic rate of reaction[kmol/kg cat s] rso3 rate of reaction for vapour sulphuric acid formation [cm6/mole.s] t temperature [k] 7. references [1] strauss, w., industrial gas cleaning. pergamon press, oxford (1975). [2] zulkifli, n. “process simulation and improvement of industrial acid gas removal unit (agru)” bsc thesis, faculty of chemical & natural resources engineering, universiti malaysia pahang (2009). [3] gomez, j. m. and cantero,d. “chapter 15 hydrogen sulfide removal from gaseous effluents” in e.r. donati and w. sand (eds.), microbial processing of metal sulfides, 287–309 (2007). [4] private communication with tebodinmuscat/oman (2012). [5] laursen, j. k. and. jensen, f. e. “wsa meeting industry demands by, sulphur 312, 80-85 (2007). [6] rosenberg, h, “wsa-dc – next generation topsoe wsa technology for stronger so2 gases and very high conversion”, the southern african institute of mining and metallurgy sulphur and sulphuric acid conference, 27-36 (2009). [7] laursen, j. k., “details advances in sulphur recovery by the wsa process-the process principles”, hydrocarbon engineering, august (2007). [8] rosenberg, h., “topsøe wet gas sulphuric acid (wsa) technology—an attractive alternative for reduction of sulphur emissions from furnaces and converters”, international platinum conference ‘platinum surges ahead’, the southern african institute of mining and metallurgy (2006). [9] wendt,a., “optimisation of wsa technology", department of chemical engineering, b.sc. thesis, lund university (2008). [10] ole rudbendixen, “sulphuric acid recovery from sulphurous waste streams” ptq q4, 1-7(1998). [11] lh/mshj, haldor topsøe a/s product sheet, sulfuric acid catalyst vk-wsa (2007). [12] guo, h. x., han, z. h. and xie, k. c. “mechanism and kinetics of so2 oxidation on "k-v"and "k-na-v" catalyst series: ( i ) catalyst behavior and reaction mechanism”, j. chem. ind. eng. (china) 37, 244-256(1984). [13] almirall, b. x., “introduction to wet sulfuric acid plants optimization through exergo economics” master’s thesis, technisceuniversitatberlin,june(2009). [14] almqvist, m. andersson, n. holmqvist a. and jönsson j., “simulation of a wsa process for so2 containing off gases from the metallurgical industry”, lund ahmed jawad ali al-dallal al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 5869 (2013) 68 university, faculty of engineering lth, department of chemical engineering haldortopsoe a/s”, ket050, (2008). [15] reiner, t; arnold, f “laboratory investigations of gaseous sulfuric acid formation via so3 + h2o + m -> h2so4 + m: measurement of the rate constant and product identification”, j chem. phys. 101, 7399–7407(1994). [16] derek d stuart, “acid dewpoint temperature measurement and its use in estimating sulfur trioxide concentration” isa 55th analysis division symposium, new orleans, session 3.3, 1 –12(2010). [17] wang, x., jin, y. g., suto, m., lee, l. c. and o'neal, h. e., “rate constant of the gas phase reaction of so3 with h2o, j. chem. phys. 89, 4853–4860(1988). [18] jayne ,j. t., pöschl ,u, chen ,y-m, dai , d., molina ,l.t., worsnop , d.r., kolb ,c.e. and molina, m.j., “pressure and temperature dependence of the gas-phase reaction of so3with h2o and the heterogeneous reaction of so3 with h2o/h2so4surfaces” j. phys. chem. a101, 10000–10011(1997). )2013( 5869، صفحة 3، العدد9مجلة الخوارزمي الھندسیة المجلد احمد جواد علي 69 الحامضي الغاز الستغالل (wsa) الرطبة بالطریقة الكبریتیك حامض أنتاج لعملیة محاكاة العماني الطبیعي الغاز من المفصول احمد جواد علي جامعة صحار/ كلیة الھندسة / الكیمیاویة قسم الھندسة الخالصة حامض إلنتاج العماني الطبیعي الغاز من أخرى غازات مع المفصول الھیدروجین كبریتید الستغالل مقترحة عملیة دراسة تمت البحث، ھذه في -aspenone. برنامج باستخدام m3/h 5000 بحدود الحامضي للغاز حجمي تدفق عند العملیة ھذه محاكات تم . (wsa) الرطبة بالطریقة الكبریتیك v7.1hysys .بالعامل المحملة الثالثة المفاعالت األول المقام في یشمل وھذا .المصنع لتشغیل المثلى الظروف لتحدید الحساسیة تحلیل اجراء كذلك تم مفاعل كل لتلقیم المثلى الحرارة درجة الى التوصل تم .للعملیة بالنسبة الزجاجة عنق تمثل التي الكبریت أكسید ثالث إلنتاج التوالي على والمربوطة المحفز تغذیة كتیار mole% so2 6 & 4 ھما لحالتین برمتھا العملیة محاكاة في الحقا أستخدامھا تم حیث المفاعل لكل المحفز العامل كمیة تحدید وكذلك حدة على داخل للعملیات نتیجة الحرارة من معتبرة كمیة تولید تم so2 %6 (%94.7) مع مقارنة ) ٪ ( 89 تحول نسبة أعلى أعطى so2 %4 .األول للمفاعل . مجاورة لوحدات التسخین عملیات في استخدامھا یمكن أو توربینات داخل طاقة الى الزائدة الحرارة ھذه تحویل أیضا ویمكن .الوحدة dr.walid.a.mahmoud /al-khwarizmi engineering journal, vol.1, no. 2, pp 1-13 (2005) î al-khwarizmi engineering journal al-khwarizmi engineering journal, vol.1, no.2,pp 1-13, (2005) ffuuzzzzyy wwaavveenneett ((ffwwnn)) ccllaassssiiffiieerr ffoorr mmeeddiiccaall iimmaaggeess dr.walid.a.mahmoud electrical engineering department college of engineering/ university of baghdad!!!!!!!!! (received 28 march 2005; accepted 11 october 2005) abstract: the combination of wavelet theory and neural networks has lead to the development of wavelet networks. wavelet networks are feed-forward neural networks using wavelets as activation function. wavelets networks have been used in classification and identification problems with some success. in this work we proposed a fuzzy wavenet network (fwn), which learns by common back-propagation algorithm to classify medical images. the library of medical image has been analyzed, first. second, two experimental tables’ rules provide an excellent opportunity to test the ability of fuzzy wavenet network due to the high level of information variability often experienced with this type of images. we have known that the wavelet transformation is more accurate in small dimension problem. but image processing is large dimension problem then we used neural network. results are presented on the application on the three layer fuzzy wavenet to vision system. they demonstrate a considerable improvement in performance by proposed two table’s rule for fuzzy and deterministic dilation and translation in wavelet transformation techniques. !! keywords: fuzzy theory, neural network ,wavelet transform, and back propagation algorithm 1. introduction artificial neural networks (anns) have been the subjects of research for over 25 years. however, it is during the last decade or so, that research interest has blossomed into commercial application, and they are now widely used as predictive classifiers, discriminators and in pattern recognition in general. recent neuralnetwork research has been directed toward the improvement of the ability of multi-layer perceptron to generalize and classify data through the design of better training algorithms and superior networks. one important, yet neglected, aspect has been to understand the exact nature of the data. anns have been employed in the field of measurement where the nature of the data is highly diverse, ranging from digital pixel values from ccds in vision systems to analogue d.c. conductance signals in a semi-conducting oxide electronic nose.. the uncertainty in the data comes in as apart of the real-world implementation itself, often attributed solely to the imprecision of the measurement. conventional anns (e.g. multi-layer perceptron) do not attempt to model the data to the another domain wave domain which constraints by fuzzy rules.. this often culminates in poorly trained networks where the problem because more significant as the uncertainty in the data increase and the size of the training set decreases. fuzzy neural networks (fwns) make use of base mother matrix (such as dr.a.barsoum electrical engineering department university of technology entather mahos electrical engineering department university of technology this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr.walid.a.mahmoud /al-khwarizmi engineering journal, vol.1, no. 2, pp 1-13 (2005) ï morelet) and fuzzy logic to model data. fwns have a relatively recent history but interest has increased through the application of wavenet and fuzzy logic in computer vision system. [1,2]. 2. artificial neural networks anns are mathematical constructs that try to mimic biological neural systems. over the years, anns have become recognized as powerful pattern recognition techniques. the networks are capable of recognition spatial, temporal or other relationships and performing tasks like classification, prediction and function estimation. ann development differs from classical programming in the fact that in modality the data variance is learnt over a number of iterations. one of the main problems of an ann approach is knowing when optimal network parameters have been found. further, as the data sets become less well behaved, the training typically becomes more difficult, and the class prediction less than satisfactory. it is generally accepted [8] that there are several advantages in applying anns as opposed to any other mathematical or statistical techniques. for instance, their generalization abilities are particularly useful since real-world data are often noisy, distorted and incomplete. in addition, it is difficult to handle non-linear interactions mathematically. in many applications, the systems cannot be modeled by other approximate methods such as expert systems. in cases where the decision making is sensitive to small to small changes in the input, neural networks play an important role. nevertheless, anns have some potential disadvantages as well, since the choice of the way in which the inputs are processed is often largely subjective and different results may be obtained for the same problem. furthermore, deciding on the optimal architecture and training procedure is often difficult, as stated above. many problems would need different subjective considerations, including speed, generalization and error minimization. anns have other potential disadvantage as well. for example, there is little formal mathematical representation of their decision and this been a major hurdle in their application in high-integrity and safety critical systems. multi-layer perceptron are most commonly used ann in pattern classification and typically comprise as input layer, an output layer and one or more hidden layers of nodes. most of our vision system has employed three layer networks (input, one hidden, and output layer), since the addition of further hidden processing layers does not provide substantial increases in discrimination power [9]. we have used an bp algorithm to learning neural networks which is used in our computer vision systems. 3. wavelet transform: in this section, some basic concept in wave let transform are briefly recalled. a. the continues wavelet transform:the continuous wavelet transform is the first studies transform. we summarized some result on continuous wave let in l2(rd), where index d stands for dimensions. if a function drx )( is radial, its fourier transform )(^  is radial as well. the transform )(x is admissible as a mother wavelet function if 1 0 2 )(^)2(      dc if function  satisfy condition(1), for any function 22 )(rlf  , its continuous wavelet transform defined as[9].   dr dx a bx xfdabafw )().(2/),(  b. the discrete wave let transform:the continues wave let transform and its inverse transform are not directly on digital computer. it must be discredited. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr.walid.a.mahmoud /al-khwarizmi engineering journal, vol.1, no. 2, pp 1-13 (2005) ð when wavelet transform is discredited, some condition should be satisfied so that this discrete version of the reconstruction of f can be actually hold. the corresponding family of dilated and translated wave lets [10]. (3) ,:2/ dznzm ma nbxd ma                    4. fuzzy theorem: fuzzy logic is a powerful technique for problem solving which has found widespread applicability in the areas of control and decision making. fuzzy logic was invented by zadeh in 1965 and has been applied over recent years to problem that are difficult to define by precise mathematical models. the approach is particularly attractive in the field of decision making, where information often has an element of uncertainty in it.[4] the theory of fuzzy logic in run relates to the theory of fuzzy sets where an effort is made to distinguish between the theory of probability and possibility. there is more than one way in which fuzziness can be introduced into neural networks and hence different works mean different things by the term ‘fuzzy neural network”. since researches define these networks as having fuzzy inputs and fuzzy outputs and hence try to fuzzify (i.e., assign a membership value to data values within the range 0-1 using a possibility distribution) before data are presented to the ann. this concept can obviously be further extended, as described, for example, by zadeh [5], where the inputs and outputs are truly fuzzified by their transformation into linguistic terms. so rather than having a particular numerical value (e.g., in the input or output), we can describe values linguistically as very low, low, moderate, high, very high, etc. this kind of fuzzification, though tempting for some application (e.g., classifying the xray images), would not be suitable for others in which the boundaries are hard to specify. fuzzy logic attempts to distinguish between possibility and probability as two distinct theories governed by their own rules. probability theory and bayesian networks can be used where the events are receptive and statistically distributed. the theory of possibility is more like a membership-class restriction imposed on a variable defining the set of values it can take. in the theory of probability, for any set a and its complement ac, a ac= null set), which is not true in the case of the theory of possibility. possibility distributions are often triangular and so similar in shape to normal distribution with mean value having the highest possibility of occurrence, which is one. any value outside the min-max range has a possibility of occurrence of zero. hence in mathematical terms, the possibility that aj is a member of the fuzzy set x={ a1 ,a2 …… an} is denoted by its membership value m (aj ). this membership value of aj in x depends upon the mean, minimum and maximum of the set x. an introductory treatment to the theory of fuzzy logic is given by mcneill and freiburger [6]. a more mathematical description of fuzzy sets and the theory of possibility are available in dubois and prade [7]. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr.walid.a.mahmoud /al-khwarizmi engineering journal, vol.1, no. 2, pp 1-13 (2005) ñ 5. fuzzy wavenets recently, simple and efficient wavelet-based methods have been developed for online learning. these fuzzy wavenets methods combine wavelet theory to fuzzy logic and neural networks. they permit to determine and validate adaptively appropriate fuzzy rules in online problems. the model is refined as more data are furnished to the system. with only a few data points, the information on the underlying surface is small and a lowresolution description of the system is appropriate, while with an increasing number of data points, a higher resolution may be justified. new rules are added to the description of the surface with increasing data points. using an automatic procedure based on the fast wavelet decomposition and reconstruction algorithm validates the rules. learning is fully automatic and does not require any external intervention, making these methods very useful in practical applications, [3]. function, s measurement, y (a) figure. 1. (a) the possibility distribution s (v:x,b,y).(b) the membership function m is related to the function s . x b!! y!! 0!! 0.5!! 1!! b y y+b/2y-b/2 measurement, y 1 0 (b) this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr.walid.a.mahmoud /al-khwarizmi engineering journal, vol.1, no. 2, pp 1-13 (2005) ò in figure (2) the first layer of fwn is the input layers, which introduces inputs into network, the second layer of fwn is the membership layer, wavelets is used as membership function. we use mexican hat function as mother wavelet, function)hat(mexicanpolywog4 )2x5.0(exp)2x1()x(  then the membership function of each linguistic variable can be achieved by translating and dilating the mother wavelet. the third layer of fwn is the rule layer. figure. 2. structure of fwn (fuzzy wavenet). x1!! xn!! p z!! n!! input layer!! rules layer: p positive, z zero, n negative y1!! yj!! ym!! zk!! z1!! member ship function layer!! output layer this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr.walid.a.mahmoud /al-khwarizmi engineering journal, vol.1, no. 2, pp 1-13 (2005) ó 6. data base library:figure 3. samples from data base medical images. (a) first image germinomal!! (b) second image mixe germ cell tumors (c) third image mixed (d) fourth image plasmacytoma!! (e) fifth image leukemia!! (f) sixth image malignant!! (j) seventh image chwannoma!! (k) eighth image hemangioperictoma!! (l) ninth image dermoid cyst!! (z) tenth image neuoglial cyst!! this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr.walid.a.mahmoud /al-khwarizmi engineering journal, vol.1, no. 2, pp 1-13 (2005) ô the algorithm of fuzzy wavenet (fwn) classifier for medical images applied as: start!! enter learning rate momentum rate initial seed integer for mlp!! random function to return the random value between 0 to seed integer!! while tsse >0.01 !! enter file images (size 100x100) gray scale or color the calculate member ship function calculate fuzzy rule layer calculate actual output for every input enter target tsse=0.5(tj-yk)^2!! save the total weight!! end!! update the weights p!! z!! n!! t0, d0 t1, d1 t2, d2 figure 4. the step of the algorithm experiment results data base. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr.walid.a.mahmoud /al-khwarizmi engineering journal, vol.1, no. 2, pp 1-13 (2005) õ where: p: represent positive fuzzy rule; n: represent negative fuzzy rule; z: represent zero fuzzy rule. t0,d0 ……. t3,d3 represent translation and dilatation in each fuzzy action. tsse: total sum square error. 7. experiment results: we propose two types of rules fwn, which contain the member ship function, depend on the three rules. number of hidden input nodes = 5050(2500), number of hidden nodes 7500, output nodes=10.the rules determine by the following table with member ship function in fig. 5: previous\actual n z p n p z n z z z z p n z p !! table 1: sets of fuzzy rule. figure 5: member ship function considered data base library with tenth images has (5050) pixels, 2500 units for input layer, and 10 for out put layers, with tested number of hidden layer. initialization weight from random function given value between (-1 to 1). training parameters for first data base library ten gray scale images (5050) hidden = (input + output)/2 desired accuracy=90% three fuzzy rules morelet bases function (x)=(1-x2)exp(-0.5*x2), wavelone=100,x(new)=(xold-t/d). x!! (x) z!!n!! p this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr.walid.a.mahmoud /al-khwarizmi engineering journal, vol.1, no. 2, pp 1-13 (2005) ö tsse 0.09 0.097 0.096 0.093 0.08 0.06 no. iteration 208 29 22 7 4 4 learning rate 0.01 0.075 0.1 0.35 0.75 0.9 for optimal value for learning rate=0.9, with minimum error and hidden nodes =7500 units show figure below: tsse 1.0 0.584 0.267 0.118 0.057 no. iteration 0 1 2 3 4 weight 0.0302 0.0512 0.0639 0.0705 0.0775 !! table 2: learning rate 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 0 0.5 1 1.5 2 2.5 3 3.5 4 no. iteration t s s e + w ei g h t tsse weight figure6: relation ship between tsse and number of iteration for three rules fwn!! table 3: initial weight this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr.walid.a.mahmoud /al-khwarizmi engineering journal, vol.1, no. 2, pp 1-13 (2005) î í to get more size such as images with 100100, need to design the greater than three rules. we proposed fwn with seven rules shown in table 3: actual/previous nb n sn z sp p pb nb pb p sp z n n nb n p p sp z sn n nb sn sp sp sp z sn n nb z z z z z z z z sp n sn sn z sp p p p n n n z p pb pb pb nb nb n z p pb pb table4: seven rules for fwn. considered data base library with tenth images has (100100) pixels, 10000 units for input layer, and 10 for out put layers, with tested number of hidden layer. (x) x!! z!!sn!!n!!nb!! sp!! p!! pb!! figure 7: member ship function for seven rules this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr.walid.a.mahmoud /al-khwarizmi engineering journal, vol.1, no. 2, pp 1-13 (2005) î î initialization weight from random function given value between (-1 to 1). training parameters for first data base library ten gray scale images (100100) desired accuracy=90% seven fuzzy rules poly 4 bases function (x)=(1-x2)exp(-0.5*x2), wavelone=100,x(new)=(xold-t/d). tsse 0.099 0.099 0.098 0.0883 0.095 0.069 no. iteration 359 49 37 12 6 6 learning rate 0.01 0.075 0.1 0.35 0.75 0.9 for optimal value for learning rate=0.9, with minimum error and hidden nodes =10000 units show figure below:tsse 1.0 0.617 0.403 0.252 0.161 0.104 0.069 no. iteration 0 1 2 3 4 5 6 weights 0.056 0.14 0.225 0.304 0.307 0.434 0.484 !! !! !! table 4: learning rate!! 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 0 1 2 3 4 5 6 no.ite ra tion t s s e + w ei g h t tsse weight figure.8: relation ship between tsse and number of iteration for seven rule fwn!! this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr.walid.a.mahmoud /al-khwarizmi engineering journal, vol.1, no. 2, pp 1-13 (2005) î ï 8. discussions: wavelet network are an alternative to sigmoid neural networks, but if add the fuzzy theory to design. the expert system which classifier the medical images with desired accuracy equal 90%, with noisy image equal 30%. for large size imaging we need to design more than fuzzy rule to deterministic the values of translation and dilation. choice for mother matrix effect on the results as number of iteration lees or greeted. the powerful for such system vision can be analysis huge data and give classified results for any small region area inside the pictures. this is most problem severed the doctor in classified or recognition the decease. the fwn don’t effect by varying number of hidden nodes because this values is constant depend on number of rules. also the learning time in fwn is very shorter if comparing with another network. the learning time of fwn decrease by 50 % with desired accuracy over than 90%. more problem was solved by fwn such as local minimum. references: [1] j-n. hwang, s-r. lay,”regression modelling in back-propagation pursuit learning”,ieee transaction on neural networks.pp.342-353, 1994. [2] a.judisky, q. zhang,”wavelets in identification: wavelets, splines, neurons, fuzzes: how good for identification?”, rapport inria no. 2315, 1994. [3] y. oussar, i. rivals,” training wavelet network for non linear dynamic inputoutput modeling “, neurocomputing (1-3), pp. 173-188, 1998. [4] chang, p.r., yeh, b.f.,“nonlinear communication channel equalization using wavelet neural network“, proc.ieee int. conf. on neural networks: ieee world congress on computational intelligence, ieee, pp.3605-3610 (1994). [5] chang, c.s., weihui fu, minjun yi,“short term load forecasting using wavelet networks“, engineering intelligent systems for electrical engineering and communications 6, 217-23 (1998). [6] daugmann,j., “complete discrete 2-d gabor transforms by neural networks for image analysis and compression“, ieee trans. acoust., speech, signal proc. 36, 1169-1179 (1988). [7] dickhaus, h., heinrich, h.,“identification of high risks patients in cardiology by wavelet networks“, proc. 18 th ieee engineering in medicine and biology, 31 oct-3 nov. 1997, ieee, vol. 3, pp.923-4 (1996). [8] echauz, j., "strategies for fast training of wavelet neural networks," 2nd international symposium on soft computing for industry, 3rd world automation congress (wac'98), anchorage, alaska, may 10-14, 1-6 (1998). [9] thuillard, m.,“applications of wavelets and wavenets in soft computing illustrated with the example of firedetectors“, spie wavelet applications vii, april 24-28 2000 (orlando), in press (2000b). [10] yeung, l.f., li, x.w.,“multi-input system identification and its applications using wavelet constructive method, proc. 35 th ieee conf. on decision and control, 1113 dec. 1996, kobe, ieee, vol. 3, pp.32305 (1996). this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr.walid.a.mahmoud /al-khwarizmi engineering journal, vol.1, no. 2, pp 1-13 (2005) î ð !! !! ! !! ! ƒ! ! !œ!¾ƒ! š!!œ!!ƒ!!!!!œ!! !! œ!!!ƒ!! !œ!! ! ! !œ!! ƒ!! !! !! ! !œ!! !!!! ! ! !! !!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! ! !!!! ! ! !!!!!! ! !!! ! !!!!!! !!!!! !!!!!!!!!!!!!!!!!!!! !!!!! ! !!!!! ! !!!! ! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!! ! !!!!! ! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!! ! !!!!! ! !!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! ! !! !! !!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!! !!! !! !!!!!!!!! !!! ! ! ! ! !œ!!!!!!! !!!! !!! ÿ!!!! !! !! !!! !!š!! ! !!!! !!! ! !! !!!! !š!!! !!!!!!!»!š!! ! !!!! !! !»! 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! !!! !! !!! !!!!! ž!!! !ÿ!!! œ!!!!! !! !¿! ! ! !!!!!! !! !š!! ! !!!! !!!!!!!!!!! !! !!!! !! !!! !! !! !!!!!!! ! !!!!!!! !!!!!!!! !! ! !! ! !! !!!!!! !! !!!!!!! this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ ياسر خضير 1 al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 8, no.4, pp 40 -52(2012) genetic algorithm based pid controller design for a precise tracking of two-axis piezoelectric micropositioning stage yasir khudhair abbas department of control and systems engineering/university of technology email: yasirkh84@yahoo.com (received 16 august 2011; accepted 13 may 2012) abstract in this paper, an intelligent tracking control system of both singleand double-axis piezoelectric micropositioner stage is designed using genetic algorithms (gas) method for the optimal proportional-integral-derivative (pid) controller tuning parameters. the (ga)-based pid control design approach is a methodology to tune a (pid) controller in an optimal control sense with respect to specified objective function. by using the (ga)-based pid control approach, the high-performance trajectory tracking responses of the piezoelectric micropositioner stage can be obtained. the (ga) code was built and the simulation results were obtained using matlab environment. the piezoelectric micropositioner simulation model with the (ga)-based pid control is illustrated to show the validity of the proposed control method for practical applications, such as scanning microscopy. keywords: piezoelectric, micropositioner, genetic algorithms, pid. 1. introduction in recent years, piezo-actuators have been widely used in high-precision positioning applications due to their special properties of: (i) nanometer and micrometer scale resolution; (ii) a high stiffness; and (iii) a fast response. however, since almost all the materials in the piezoactuators are ferroelectric, their responses to applied electric fields exhibits fundamental hysteresis behavior. this always leads to the severe inaccuracies and instabilities when the piezo-actuator is operated in an open-loop fashion [1]. moreover, the hysteresis characteristics of piezo-actuators are usually unknown and it is difficult to establish a dynamic model for systems with a hysteresis effect. these cause increased difficulties in using piezo-actuated motion systems in positioning control situations with high performance requirements [2, 3]. many researchers deal with the problem of precise tracking control of a piezoelectric actuators and micropositioner stages. in 2004, shieh et al, [1] proposed an adaptive backstepping displacement tracking control for piezoelectric actuating mechanism. the trajectory tracking of a large-displacement piezoelectric actuator (ldpa) using a nonlinear observer-based variable structure control (vsc) was developed by hwang; et.al. in 2005 [4]. the intelligent control systems are employed also to implement a precise tracking for the micropositioner stage. in 2006, lin et al. [5] who proposed an adaptive wavelet neural network (awnn) control with hysteresis estimation to control performance of a piezo-positioning mechanism. in the field of optimal control, shieh in 2008 [6] utilize the optimal lqr control approach to tune a pid controller to control a micropositioner stages position in an effective way. this paper endeavors to design a control system using genetic algorithm to accurately control a piezoelectric micropositioner. genetic algorithm or in short ga is a stochastic algorithm based on principles of natural selection and genetics, in other words, it is a stochastic global search method that mimics the process of natural evolution. using genetic algorithms to perform the tuning of the controller will result in the mailto:yasirkh84@yahoo.com yasir khudhair abbas al-khwarizmi engineering journal, vol. 8, no.4, pp40 -52 (2012) 41 optimum controller being evaluated for the system every time [7]. genetic algorithms (gas) were invented by john holland in the 1960s and were developed by holland and his students and colleagues at the university of michigan in the 1960s and the 1970s. in contrast with evolution strategies and evolutionary programming, holland's original goal was not to design algorithms to solve specific problems, but rather to formally study the phenomenon of adaptation as it occurs in nature and to develop ways in which the mechanisms of natural adaptation might be imported into computer systems. holland's 1975 book adaptation in natural and artificial systems presented the genetic algorithm as an abstraction of biological evolution and gave a theoretical framework for adaptation under the ga. holland's ga is a method for moving from one population of "chromosomes" (e.g., strings of ones and zeros, or "bits") to a new population by using a kind of "natural selection" together with the genetics−inspired operators of crossover, mutation, and inversion. each chromosome consists of "genes" (e.g., bits); each gene is an instance of a particular "allele" (e.g., 0 or 1) [8]. it is worth mentioning, that the (gas) start with no knowledge of the correct solution and depends entirely on responses from their environment and evolution operators such as reproduction, crossover, and mutation to arrive to the best solution. by starting at several independent points and searching in parallel, the algorithm avoids local minima and converging to suboptimal solutions [9]. the paper is outlined in the following way: sec. 2 explains the physical background of the piezoelectric actuators in general. sec. 3 gives the necessary description of the piezoelectric micropositioner device. sec. 4 gives the modeling of the piezoelectric micropositioner. the genetic algorithm is explained in sec. 5 while the tuning of pid using genetic algorithm is illustrated in sec. 6. the simulation results and the analysis of the results are given in sec. 7. finally the conclusion is presented in sec. 8. 2. physical background of piezoelectric actuators the piezoelectric actuator (pea) is a wellknown commercially available device for managing extremely small displacements in the range of 10 pm (pm=10 m) to 100 . the ratio of the input voltage and the output elongation is very satisfactory for this purpose. a disadvantage, however, is its highly nonlinear input/output behavior. more specifically, a pea shows hysteresis behavior. in simple terms, this means that for a certain input, there is no unique output. instead, the output depends on the input history. for high-accuracy positioning and tracking systems, the piezo-actuated positioning mechanism should be equipped with a controller. modern controller design is based on a model of the system to be controlled. for piezo-actuated positioning mechanisms, the dynamical aspects of the pea play a dominant role [10]. dielectric materials are insulators, thus, there is an electrical relation between electrical voltage and electrical charge. piezoelectric is a special type of dielectric in the sense that, in piezoelectric materials, an externally applied force induces an electrical charge. conversely, an applied electrical charge induces a force [10]. the former effect is known as the piezoelectric effect and was discovered in 1880 by the curie brothers. the latter effect is the inverse piezoelectric effect. both pressure electricity and piezoelectricity were used to describe the same phenomenon. besides the piezoelectric and inverse piezoelectric effect, there are already mentioned electrical relation between voltage and charge, and a mechanical relation between force and elongation [11]. . ⎯⎯ ⎯⎯ . ⎯⎯ fig. 1. schematic representation of the different relations in a pea. in fig. (1), a schematic representation of the different relations is given. the piezo effect is the connection between the electrical and mechanical domains. due to this effect, piezoelectric are potentially useful as electromechanical actuators. in naturally occurring piezoelectric materials, such as quartz, the (inverse) piezoelectric effect is too small to be of practical use. fabricated piezoelectric polycrystalline ceramics are much more suitable for actuator purposes because the proper mixture of ingredients can influence the useful properties, such as maximum elongation. a disadvantage of fabricated piezoelectric ceramics is that a hysteresis effect is encountered between electrical voltage and electrical charge [11]. historical perspectives of the piezoelectric effect as well as recent advances in ceramic and thin film actuators are provided in [12, 13], and [14]. yasir khudhair abbas al-khwarizmi engineering journal, vol. 8, no.4, pp40 -52 (2012) 42 3. description of the piezoelectric micropositioner the double-axis micropositioner driven by stacked piezo-actuators used in this study is a micropositioner with displacement range of (0 – 80 ) in the x and y directions. the outline sketch of this stage is shown in fig. (2-a), and it contains the following elements: stacked piezoactuator, heavy base, flexure mount, lever arm, movable top plate, and strain-gauge transducers. its single-axis motion working principle can be shown in fig. (2-b). the main body of the stage is fixed to a heavy base and the movable plate on the top of the stage is a platform for the components mounted to be scanned. the movement of the top plate is due to an internal lever-transmission of extension of the built-in stacked piezo-actuators with solid state flexure hinges. when an input voltage is applied to the stage, the extension of the stacked piezo-actuators occurs and then this extension causes the bending of the flexure mounts. this bending gives rise to a deviation of the top plate [15]. -a -b fig. 2. aoutline sketch. bworking principle of the piezo-positioning stage. a block diagram for a control system setup of the piezoelectric micropositioner is shown in fig. (3), which contains has a voltage amplifier, signal conditioner, and computer with data acquisition interface. fig. 3. a block diagram for a control system setup of the piezoelectric micropositioner. in fig. (3), the equipped devices are briefly described as follows [6]: i. voltage amplifier was developed by high voltage – type op-amplifier with model pa240, manufactured by apex microtechnology, usa, which has the specification of maximum peak-peak voltage 350v, maximum output current of 250 ma, and bandwidth of 3mhz. moreover, the linear amplification gain of 5 is set. the amplifier implementation for driving the piezoelectric micropostioner is shown in fig. (4), in which a phase lead-lag compensator is cascaded to obtain an improved stability in the sense of bode diagram. ii. signal conditioner for strain gauge transducer was set up by chip with model 1b32, produced by (analog devices, inc.). the output voltage range was set to (0 -10) v for the ranged displacement of (0−80μm). iii. a computer for control algorithm implementation and a data acquisition board with analog to digital (a/d) and digital to analog (d/a) conversion were applied. yasir khudhair abbas al-khwarizmi engineering journal, vol. 8, no.4, pp40 -52 (2012) 43 fig. 4. diagram of the drive amplifier circuit for the piezoelectric micropositioner. to show the usability of the driving amplifier and strain gauge signal conditioner, a triangular displacement-trajectory response from the piezoelectric micropostioner without control approach implementation is shown in fig. (5) [6]. it appears from fig. (5) that the established control system in this study consists of the piezoelectric micropositioner, driving amplifier, strain-gauge signal conditioner is applicable for controller development. fig. 5. output displacement response from the open-loop piezoelectric micropositioner. 4. modeling of piezoelectric micropositioner system for suitability of controller development, a dynamic model of the piezoelectric micropositioner which is a second order linear transfer function model is considered in this study. originally this model is identified by using a dynamic signal analyzer that is used to capture the magnitude response in frequency domain. then, a curve fitting tool in matlab computer software is adopted to find out an approximated second-order linear transfer function whose magnitude response in frequency domain is very close to the actual one captured by the dynamic signal analyzer. the second-order linear transfer function determined by the curve fitting method is given as follows [6]: ( ) ( ) = . . . …(1) where: ( ): denotes the output displacement. ( ): denotes the input voltage. to confirm the accuracy of the identified mathematic model (eq. (1)), the magnitude responses in frequency domain of the actual system and the mathematic model are shown in fig. (6). from fig (6), it appears that the identified mathematic model approaches the actual one. in other words, the identified model can be adopted for controller development in a ranged frequency domain [6]. fig. 6. magnitude response in frequency domain from the piezoelectric micropositioner and the identified model. furthermore, a displacement time-response of both the practical system and identified model to a triangular trajectory is shown in fig. (7) to validate the mathematic model of (eq. (1)). yasir khudhair abbas al-khwarizmi engineering journal, vol. 8, no.4, pp40 -52 (2012) 44 fig. 7. a displacement time-response of both the practical system and identified model to a triangular trajectory [6]. according to (eq. (1)), the following states are defined: = , = ̇ …(2) where: : denotes the displacement. : denotes its velocity. with the assumption of eq. (2), the linear state equation corresponding to (eq. (1)) can be expressed by: ̇ = + = …(3) where: = 0 1− − = 0 1−30695.04 −350.48 , = = 030695.04 . and, = [1 0] before we designing a ga based pid controller for the piezoelectric micropositionor stage system (eq. (1)), the system should be tested for controllability properties. in order to test system controllability, the controllability matrix is first calculated as follows: s = [b ab] …(4) where: : controllability matrix. a , and b are the piezoelectric micropositioner stage system state space matrices. substituting the above state space matrices into eq.(4) above yield: s = 0 30695−30695.04 −1.0758 × 10 …(5) the rank of the above controllability matrix is found to be 2, which means that the system is fully controllable. 5. genetic algorithm genetic algorithm is a powerful search algorithm that performs an exploration of the search space that evolves in analogy to the evolution in nature [16]. (gas) use probabilistic transition rules instead of deterministic rules, and handle a population of potential solutions known as individuals or chromosomes that evolve iteratively. each iteration of the algorithm is termed as a generation. the evolution of solutions is simulated through a fitness function and genetic operators such as reproduction, crossover and mutation. the fittest individual will survive generation after generation, and will also reprodue and generate offsprings that might be stronger. at the same time, the weakest individuals disappear from each generation [17]. a genetic algorithm (fig. (8)) is typically initialized with a random population. this population (mating pool) is usually represented by a real-valued number or a binary string called a chromosome. how well an individual performs a task is measured and assessed by the objective function, which assigns each individual a corresponding number called its fitness. the fitness of each chromosome is assessed and a survival of the fittest strategy is applied [18]. there are three main operators for a genetic algorithm – reproduction, crossover and mutation. yasir khudhair abbas al-khwarizmi engineering journal, vol. 8, no.4, pp40 -52 (2012) 45 fig. 8. flowchart of ga programming. 5.1. reproduction during the reproduction phase the fitness value of each chromosome is assessed. this value is used in the selection process to provide bias towards fitter individuals. just like in natural evolution, a fit chromosome has a higher probability of being selected for reproduction [9]. an example of a common selection technique is the ‘roulette wheel’ selection method;see fig. (9). each individual in the population is allocated a section of a roulette wheel; the size of the section is proportional to the fitness of the individual. a pointer is spun and the individual to whom it points is selected. this continues until the selection criterion has been is met [19]. fig. 9. depiction of roulette wheel selection. 5.2. crossover once the selection process is complete, the crossover algorithm is initiated. the crossover operations swap certain parts of the two selected strings in a bid to capture the good parts of old chromosomes and create better new ones. genetic operators manipulate the characters of a chromosome directly, using the assumption that certain individual’s gene codes, on average, produce fitter individuals. the crossover probability indicates how often crossover is performed. a probability of 0% means that the ‘offspring’ will be exact replicas of their ‘parents’ and a probability of 100% means that each generation will be composed of entirely new offspring. the simplest crossover technique is the single point crossover [9,18]. 5.3. mutation using selection and crossover on their own will generate a large amount of different strings. however there are two main problems with this: 1. depending on the initial population chosen, there may not be enough diversity in the initial strings to ensure the ga searches the entire problem space. 2. the ga may converge on sub-optimum strings due to a bad choice of initial population. these problems may be overcome by the introduction of a mutation operator into the ga. mutation is the occasional random alteration of a value of a string position. it is considered a background operator in the genetic algorithm. the probability of mutation is normally low because a high mutation rate would destroy fit strings and degenerate the genetic algorithm into a random search. mutation probability values of around 0.1% or 0.01% are common. these values represent the probability that a certain string will be selected for mutation i.e. for a probability of 0.1%. one string in one thousand will be selected for mutation [9, 18]. 6. ga based tuning of the controller the optimal value of the pid controller parameters , , are to be found using ga. all possible sets of controller parameter values are particles whose values are adjusted to minimize the objective function, which in this case is the error criterion, and it is discussed in detail. for the pid controller design, the initialize population measure fitness selection mutation crossover optimum solutions not optimum solutions yasir khudhair abbas al-khwarizmi engineering journal, vol. 8, no.4, pp40 -52 (2012) 46 controller settings estimated results in a stable closed loop system are ensured. 6.1. objective function for the ga the objective functions considered are based on the error criterion. a number of such criteria are available. in this paper controller’s performance is evaluated in terms of integral time absolute error criteria (itae). the error criterion is given as a measure of performance index given by the equation for the integral of time multiplied by absolute error (itae) [18]: = ∫ | ( )| …(6) where: t: final time of simulation. 7. implementation of ga based pid controller to ensure optimal control performance at nominal operating conditions, ga can be applied to the tuning of pid controller gains (where this ga is programmed using m-file [matlab file] code). the block diagram (fig. (10)) for the entire system is given below and also the genetic algorithm parameters chosen for the tuning purpose are shown in table (1). table 1, parameters of ga. ga property value / method population size 10 maximum number of generations 10 the range of tuning parameters 4-4.5 221230 0.0080.0085 performance index/fitness function itae selection method roulette wheel crossover method arithmetic crossover crossover probability 0.8 mutation method uniform mutation probability 0.05 termination condition for ga maximum number of generation is achieved or the value of fitness is fixed for next generations 7.1. simulation and analysis of results after giving the above parameters to ga, the pid controllers can be easily tuned, the proper optimized gain values of controller are obtained with the implementation of ga based pid controller given in table (2) . table 2, ga based pid controller gain values. gain parameters values 4.04877 222.27698 0.0084 to show the performance of the control system, simulation time responses from the piezoelectric micropositioner with the proposed genetic pid controller are carried out with matlab-simulink (r2009a) package. 7.1.1. single-axis simulation results the single-axis (either x or y direction) piezoelectric micropositioner stage is simulated using the gain parameter values taken from table (2) with the following desired test signals: test signal1: step function with magnitude=1 μm test signal2: sinusoidal function = asin(10t) , where the amplitude a is 1 μm. test signal3: square function with amplitude equal to 1 μm and frequency equal to 10 ⁄ . the simulation results of the single-axis piezoelectric micropositioner stage are shown in fig. (11-a) for the test signal1, while the control action is shown in fig. (11-b). it can be noticed that the system succeed to reach to its desired position in less than (0.015 sec) with a smooth behavior. for further confirmation, the validity of the control system in many practical applications, the time responses to commanded sinusoidal and square trajectories (test signal 2 & 3) with amplitude 1 μm are obtained. for the test signal2, the simulation results of the single-axis piezoelectric micropositioner stage are shown in fig. (12-a). it is very clear that the proposed genetic pid controller is able to track the desired sinusoidal reference efficiently. the control action is shown in fig. (12.b). for the test signal 3 it is noticed in fig. (13-a) that the pid based ga controller is also able to track the reference signal also with efficient manner. the control action for yasir khudhair abbas al-khwarizmi engineering journal, vol. 8, no.4, pp40 -52 (2012) 47 the pid based ga controller under test signal 3 can be seen in fig. (13-b). 7.1.2. double-axis simulation results in order to obtain a circle-shaped trajectory for the double-axis piezoelectric micropositioner stage, the following desired references for both x and y-axis are chosen to be: x− axis ref = a sin(10t), y− axis ref = a sin 10t + π …(7) where a = 1 μm the time response of the commanded xand y-axis stages are shown in fig. (14-a) and fig. (14-b), while the control actions of both xand y-axis stages are illustrated in fig. (14-c). the efficient tracking of both stages to the desired references is an evident to the potential of the designed optimal pid based ga controller. the circular-shaped trajectory is shown in fig. (15), where the piezoelectric micropositioner is able to track a circle trajectory with 1 μm radius. fig. 10. block diagram of the entire piezoelectric micropositioner system. fig. 11. simulation results with test signal 1 of single-axis piezoelectric micropositioner stage position. atimeresponse. bcontrol action. ( ) ga based pid controller ( ) piezoelectric micropositioner system reference position output position yasir khudhair abbas al-khwarizmi engineering journal, vol. 8, no.4, pp40 -52 (2012) 48 fig. 12. simulation results with test signal 2 of single-axis piezoelectric micropositioner stage position. atime response. bcontrol action. fig. 13. simulation results with test signal 3 of single-axis piezoelectric micropositioner stage position. atime response. bcontrol action. yasir khudhair abbas al-khwarizmi engineering journal, vol. 8, no.4, pp40 -52 (2012) 49 fig. 14. simulation results with sinusoidal ref. inputs of double-axis piezoelectric micropositioner stage position. atime response of x-axis. btime response of y-axis. cdouble-axis control action. fig. 15.simulation results of piezoelectric micropositioner stage circle trajectory. yasir khudhair abbas al-khwarizmi engineering journal, vol. 8, no.4, pp40 -52 (2012) 50 8. conclusions this paper is dedicated to design a control system of a piezoelectric micropositioner, where the control system was developed with the ga pid controller. the ga is used to optimally select the best pid parameters as shown in table (2), consequently the system response is enhanced, which verify the efficiency of ga as suitable optimization method. to design the ga pid, an approximated linear second-order transfer function is used. to confirm the validity of the proposed control approach, a simulation program created by using matlab package for piezoelectric micropositioner with ga pid was carried out. finally, the simulation results illustrated the validity of the proposed control system for practical applications in singleaxis trajectory tracking and double-axis scanning. this shows that the proposed control approach is perfectly applicable to scanning application. notations ( ): output displacement. ( ): input voltage. : displacement state variable. : velocity state variable. , , piezoelectric state space coefficient matrices s: controllability matrix. : absolute error criteria. ( ): error function. t: final time of simulation. proportional gain. integral gain. derivative gain. 9. references [1] h.-j. shieh, f.-j. lin, p.-k. huang and l.-t. teng, “adaptive tracking control solely using displacement feedback for a piezopositioning mechanism”, iee proceedings control theory and applications, vol. 151, no. 5, september, 2004, pp. 653–660. [2] g. s. choi, h. s. kim, and g. h. choi, “a study on position control of piezoelectric actuators”, proceedings of the ieee international symposium on industrial electronics (1997. isie '97), vol. 3, 1997, pp. 851–855. [3] p. ge, and m. jouaneh, “tracking control of a piezoceramic actuator”, ieee transactions on control systems technology, vol. 4, no.3, 1996, pp. 209–216. 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[17] k.f. man, k.s. tang, and s. kwong, “genetic algorithms: concepts and applications”, ieee transactions on industrial electronics, vol. 43, no. 5, 1996, pp. 519 534. [18] s.m. g. kumar, r. jain, n. anantharaman, v. dharmalingam, and k.m.m. s. begum, “genetic algorithm based pid controller tuning for a model bioreactor", journal of indian chemical engineer, vol. 50, no. 3, july-september 2008, pp. 214226. [19] a. chipperfield, p. fleming, h. pohlheim, and c. fonseca, “genetic algorithm toolbox for use with matlab, user guide”, version 1.2, university of sheffield, uk, 1994. )2012( 4052، صفحة 4، العدد8مجلة الخوارزمي الھندسیة المجلد یاسر خضیر عباس 52 تفاضلي باإلعتماد على الخوارزمیات الجینیة لغرض تتبع دقیق -تكاملي-تصمیم مسیطر تناسبي لنظام تموضع كھروإجھادي ذو محورین یاسر خضیر عباس الجامعة التكنولوجیة/ قسم ھندسة السیطرة والنظم yasirkh84@yahoo.com : البرید اإللكتروني الخالصة طریقة بإستخدام محورین وذات واحد محور ذات لمرحلة تموضع كھروإجھادي نظام على السیطرة لغرض للتتبع ذكي نظام تصمیم تم ، البحث ھذا في على باإلعتماد التفاضلي -التكاملي -التناسبي المسیطر تصمیم طریقة إن . تفاضلي -تكاملي تناسبي مسیطر معامالت تنغیم لغرض الجینیة الخوارزمیات یمكن المسیطرات من النوع ھذا بإستعمال . محددة ھدف دالة على باإلعتماد المثلى السیطرة سیاق ضمن المسیطر لتنغیم طریقة ھي الجینیة الخوارزمیة تم التي المحاكاة ونتائج الجینیة الخوارزمیات شفرة بناء إن. الكھروإجھادي التموضع لنظام عالیة إداء بمواصفات التتبع لمسار إستجابات على الحصول تم الجینیة قد الخوارزمیة على المعتمد التفاضلي -التكاملي -التناسبي المسیطر مع المحاكاة نموذج وكذلك matlabبیئة الحصول علیھا تم من خالل .المسح المجھري مثل العملیة للتطبیقات المقترحة السیطرة طریقة صالحیة إظھار لغرض توضیحھ mailto:yasirkh84@yahoo.com al-khwarizmy engineering journal,4,2,(2012) al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 8, no. 2, pp 84 96 (2012) channel estimation and prediction based adaptive wireless communication systems abeer o. al-shammari* khalifa a. salim** mohammed a. abdalla*** *information technology directorate/ ministry of science and technology/ iraq **department of information and communication engineering/al-khawarizmi college of engineering/ university of baghdad *** department of information and communication engineering/college of information engineering/ university of al-nahrain *email: abeeralshammari1985@gmail.com ** email: khalifa.kcebu@uobaghdad.edu.iq *** email: mohammedalmushdany@yahoo.com (received 8 march 2011; accepted 9 january 2012) abstract wireless channels are typically much more noisy than wired links and subjected to fading due to multipath propagation which result in isi and hence high error rate. adaptive modulation is a powerful technique to improve the tradeoff between spectral efficiency and bit error rate (ber). in order to adjust the transmission rate, channel state information (csi) is required at the transmitter side. in this paper the performance enhancement of using linear prediction along with channel estimation to track the channel variations and adaptive modulation were examined. the simulation results shows that the channel estimation is sufficient for low doppler frequency shifts (<30 hz), while channel prediction is much more suited at high doppler shifts with same snr and target ber=10-4. it was shown that the performance at higher doppler frequency shifts (<30hz) was improved by more than 2db over channel estimation at target ber=10-4 and 32qam constellation used. keywords: channel estimation, adaptive communication. 1. introduction wireless communications is an emerging field, which has seen enormous growth in the last several years [1]. the transmission performance and throughput of wireless communication systems is limited due to random variation of the channel. the exponential growth of the internet had resulted in an increased demand for new methods to obtain high capacity wireless networks. the wireless radio channel poses a severe challenge as a medium for reliable highspeed communication. it is not only susceptible to noise, interference, and other channel impediments, but these impediments change over time [2]. the basic idea behind adaptive transmission is to maintain a constant signal to noise ratio (snr). thus, without sacrificing bit error rate (ber), these schemes provide high average spectral efficiency by transmitting at high speeds under favorable channel conditions, and reducing throughput as the channel degrades [3]. extensive research work was carried to improve the transmission rate over wireless link and efficient use of allowable bandwidth, using adaptive transmission techniques, such as adaptive modulation, channel coding, power control, and antenna diversity [4,5,6]. the transmission scheme is selected relatively to the channel characteristics [7]. for very slowly fading channels, outdated csi is sufficient for reliable adaptive communication while for faster fading, even small delay will cause significant degradation of performance since channel variation due to large doppler shifts usually mailto:khalifa.kcebu@uobaghdad.edu.iq mailto:mohammedalmushdany@yahoo.com abeer o. al-shammari al-khwarizmi engineering journal, vol. 8, no. 2, pp 84 96 (2012) 85 results in a different channel at the time of transmission than at the time of channel estimation. due to unavoidable delays involved in signal estimation, feedback transmission, and modulation adjustment; the adaptation needs to be based on predicted channel rather than estimated one [7]. the rest of the paper is organized as follows. in the next section m-ary quadrature amplitude modulation mqam technique was presented. wireless channel modeling, estimation, prediction are discussed in section 3, system architecture and simulation in section 4 and results and conclusions are discussed in section 5. 2. m-ary quadrature amplitude modulation mqam spectrum is the most precious commodity in wireless communications. along with snr, it determines the data rate at which the information can be transmitted. in spectrally efficient m-ary qam (mqam), there are a total of (m) possible states for the signal with transition from any state to any other state at every symbol time. since m=2m, m bits per symbol can be sent. in adaptive mqam the transmission parameters are varied according to variation of the channel state. for every modulation mode, its error probability is directly related to the received snr. the symbol error rate (ser) of mqam is given as [8]: 𝑃𝑠,𝑀𝑄𝐴𝑀(𝛾) = 2(√𝑀−1) √𝑀 𝑄 (√ 3 𝑀−1 𝛾) …(1) where () is the received snr. this approximation to the error probability is good for all values of m. when the gray coding is used in the mapping of bits to constellation symbol, the equivalent bit error rate (ber) for mqam is well approximated by [8]: 𝑃𝑏,𝑀𝑄𝐴𝑀(𝛾) = 1 𝑙𝑜𝑔2√𝑀 𝑃𝑠,𝑀𝑄𝐴𝑀(𝛾) …(2) in adaptive mqam system, modulation is selected according to the channel state which is obtained in the form of signal to noise ratio. 3. channel modeling unreliable wireless communication channel is resulted due to temporal and spatial variations of the received signal [8]. besides the path loss, shadowing, and multipath fading the inherent noise from the receiver's electronics and interference from competing transmissions complicated the recovery of the original signal. multipath fading is the dramatic variation in signal power that occurs when the received signal is a sum of multipath components each with independent amplitude, phase, and frequency components. fading is caused by a phenomenon known as the doppler effect [8]. fd = fc v c ∙ cosθ = fdmaxcosθ …(3) where fc is the carrier frequency, θ is the angle of arrival of the received signal, v is the relative velocity, and fdmax is the maximum doppler frequency. the received signal was modeled as a sum of non-resolvable multipath components each with independent amplitude, phase and frequency components. the channel is thus modeled in a complex baseband as [9,10]. c(t) = ∑ ai n i=1 . ej(2πfdit+θi) …(4) where n is the number of scatterers, ai is the amplitude, and fdi is the doppler frequency shift of the ith complex sinusoid. figure(1) shows a typical rayleigh fading channel simulated over different doppler frequency shifts. the multipath fading channel was modeled as a linear finite impulse response fir filter using matlab7.6. the envelope of the channel was faded throughout the channel samples. the fading rate is highly dependent upon doppler frequency shift. fig. 1. rayleigh fading envelope. abeer o. al-shammari al-khwarizmi engineering journal, vol. 8, no. 2, pp 84 96 (2012) 86 4. proposed system architecture figure (2) shows the proposed system block diagram. where r(t), s(t), c(t) and n(t) is the received, transmitted, channel and noise signal respectively. a pilot symbol which does not convey useful information is inserted every lth channel symbol for real time channel monitoring, where each frame starts with a pilot symbol. the frame length (l) can be adjusted depending on the channel quality. the proposed system uses bandwidth efficient mqam modulation technique with different levels. the randomly generated symbols are first mapped into m possible phases using gray coding. fig. 2. system architecture. received pilot symbols are extracted and used for channel estimation. the modulated symbols are then converted back to baseband bits with appropriate demodulation and gray decoding. coherent demodulation is used in order to achieve an undistorted bit stream. in order to cope with channel variations, the received data are fed through a baseband equalizer to reduce signal distortion. it is worthy to note that perfect clock and carrier recovery is assumed. the estimated channel values are fed back to the transmitter to adjust the transmission mode suitable for the channel state at the transmission time. 4.1. adaptive modulation boundaries switching between different modulation schemes was based on ber threshold which is directly related to the channel snr, at the receiver. recall equation (2) snr can be found as: 𝛾 = 10 ∗ 𝑙𝑜𝑔10 (𝑄−1( 𝑃𝑏,𝑀𝑄𝐴𝑀(𝛾)∗√𝑀∗𝑙𝑜𝑔2√𝑀 2(√𝑀−1) )) 2 3 (𝑀−1)⁄ …(5) where q-1 is the inverse of the q-function. proper switching boundaries are decided based on target ber selected specified depending on the type of information to be transmitted over the channel (voice, video, data,…etc). this means that the system will try to keep a ber lower than a target ber with the most spectrally efficient modulation scheme whenever possible. figure (4) shows the ber performance for mqam over awgn channel with target ber=10-3. transmitter rayliegh channel receiver n(t) modulation detection channel estimation channel prediction x + adaptive rate control s(t) pilot insertion c(t) pilot extraction r(t) feedback channel abeer o. al-shammari al-khwarizmi engineering journal, vol. 8, no. 2, pp 84 96 (2012) 87 fig. 4. ber performance for mqam in awgn channel with threshold ber=10-3 . different modulation techniques were simulated over a rayleigh fading channel with different doppler frequency shifts. fig. (5) and fig. (6) show the ber performance for 64qam and 256qam over rayleigh fading channel. fig. 5. 64qam ber performance over rayleigh channel . abeer o. al-shammari al-khwarizmi engineering journal, vol. 8, no. 2, pp 84 96 (2012) 88 fig. 6. 256qam ber performance over rayleigh channel . 4.2. channel estimation the ultimate goal at the receiver is to recover the transmitted signal that was subjected to both time varying attenuation and phase distortion. using pilot symbols accurate channel values can be obtained at the pilot times. in order to obtain the channel impulse response, the channel values can be interpolated. fft-based interpolation approach was used to interpolate in between channel values. the input data to the channel estimator is the ratio of the received pilot symbols to the known pilot symbols g(n) [7]. this factor gives a measure of the distortion that the pilot symbol has undergone due to the channel fading. 𝐺(𝐾) = ∑ 𝑔(𝑛)exp (− 𝑗2𝜋𝑛𝑘 𝑁𝑝 𝑁𝑝−1 𝑛=0 ) …(6) where np is the number of pilot symbols used to create channel estimate. both snr and the doppler frequency shift have a strong impact on the performance of channel estimation and hence rate adaptation. the effect of different values of doppler frequency shift on channel estimation was simulated as shown in figure (7). a. doppler frequency= 5 hz. 1050 1055 1060 1065 1070 1075 1080 1085 1090 1095 1100 -10 0 10 20 30 40 50 system identification doppler frequency=5hz time index si gn al v al ue desired fft e stimated abeer o. al-shammari al-khwarizmi engineering journal, vol. 8, no. 2, pp 84 96 (2012) 89 b. doppler frequency=30 hz. c. doppler frequency=40 hz fig. 7. fft estimation of signal transmitted over rayleigh fading channel. 4.3. channel prediction in channel prediction, the future power level of the channel can be estimated using past and present channel samples [11]. unlike awgn the channel is correlated from sample to sample. therefore, advantage of the deterministic properties can be taken and what the value of the channel will be at a later time can be predicted. in the linear prediction (lp) model, the current sample is approximated by a linear combination of past samples of the input signal [10,12,13]: 𝑐�̀� = ∑ 𝑑𝑗 𝑝 𝑗=1 𝑐𝑛−𝑗 ...(7) where 𝑐�̀� is the predicted value based on the linear combination of (𝑝) previous values (𝑐𝑛−𝑗) multiplied by the prediction coefficients(𝑑𝑗). and the error generated by this estimate is [14]: 𝑒𝑛 = 𝑐𝑛 − 𝑐�̀� …(8) where 𝑐𝑛 is the true channel value. in order to predict multiple samples in the future, the latest predicted sample is just treated as an actual sample. in linear prediction the state of the channel will be up to date at the time the transmitter receives the control information from the receiver hence propagation delay of the feedback channel will be less of a problem. 1050 1055 1060 1065 1070 1075 1080 1085 1090 1095 1100 -10 0 10 20 30 40 50 system identification doppler frequency=30hz time index si gn al va lue desired fftestimated 1050 1055 1060 1065 1070 1075 1080 1085 1090 1095 1100 -10 0 10 20 30 40 50 system identification doppler frequency=40hz time index si gn al v al ue desired fftestimated abeer o. al-shammari al-khwarizmi engineering journal, vol. 8, no. 2, pp 84 96 (2012) 90 in order to predict the rayleigh fading channel, channel estimation followed by linear prediction will be employed. a linear predictor is used to predict the channel status based on the outdated estimates. figures from (8) to (10) show the prediction of future channel values. the prediction efficiency is depending on the number of symbols that could be predicted ahead. as the number of symbols increases, the accuracy of the prediction would be decrease. fig. 8. linear prediction for 1 symbols ahead. fig. 9. linear prediction for 10 symbols ahead. fig. 10. linear prediction for 20 symbols ahead. abeer o. al-shammari al-khwarizmi engineering journal, vol. 8, no. 2, pp 84 96 (2012) 91 ber performance of 64qam and 256qam simulated over predicted channel with different prediction depth (10 and 20 samples ahead) is shown in fig. (11) and fig. (12). fig. 11. 64qam ber performance for predicted rayleigh fading channel . fig. 12. 256qam ber performance for predicted rayleigh fading channel . 5. results and conclusions it is worthy to note that the channel estimation and prediction at the receiver side differ from the original rayleigh channel because of the error due to estimation and prediction process. as doppler frequency increases, the ber also increases because of the deep fades that occur on rayleigh channel during data transmission. from previous results it can be concluded that the ber performance over predicted channel with 10 symbols ahead is better than the ber performance over predicted channel with 20 symbols ahead since as farther as many samples predicted, the less accuracy of the channel will be observed because of accumulated error. figures (13-14-15) show the ber performance for 32qam, 64qam and 256qam constellations with different values of doppler frequency shift for each case simulated over original, estimated, and predicted rayleigh fading channels. the results clearly reveal that the channel estimation was sufficient for low doppler abeer o. al-shammari al-khwarizmi engineering journal, vol. 8, no. 2, pp 84 96 (2012) 92 frequency shifts (<30 hz). at higher doppler shifts the channel estimator fails to track the channel variations due to high fading rate, while channel prediction is much more suitable at high doppler shifts and same snr. channel prediction based on the estimated channel samples was simulated and tested for target ber=10-4. it was shown that the performance at higher doppler frequency shifts was improved by more than 2db over channel estimation and 32qam modulation used. higher constellation size is more sensitive to increased doppler shift. fig. (16) shows that the ber performance of adaptive system is much better than static system because it provides efficient spectral efficiency at any given snr. the reason for such improvement is that when a channel encounters a deep fade, it is better to use a modulation with lower constellation size in order to get low error probability, while in good channel state it is better to transmit as many bits as possible. as a result, in order to overcome the outdated csi ,when channel estimation is used, past and present channel symbols can be used to predict future channel symbols. fig. 13. channel estimation and prediction 32qam. a. doppler frequency=20 hz. 10 15 20 25 10 -6 10 -5 10 -4 10 -3 10 -2 10 -1 10 0 eb/no (db) b e r channel estimation and prediction for 32qam with doppler frequency=30hz original channel estimated predicted 20 21 22 23 24 25 26 27 28 29 30 10 -6 10 -5 10 -4 10 -3 10 -2 10 -1 10 0 eb/no (db) b e r channel estimation and prediction for 64qam with doppler frequency=20hz original channel estimated predicted abeer o. al-shammari al-khwarizmi engineering journal, vol. 8, no. 2, pp 84 96 (2012) 93 b. doppler frequency=30 hz. fig. 14.channel estimation and prediction for 64qam. a. doppler frequency=15 hz. b. doppler frequency=20 hz. fig. 15.channel estimation and prediction 256q am. 20 25 30 35 10 -6 10 -5 10 -4 10 -3 10 -2 10 -1 10 0 eb/no (db) be r channel estimation and prediction for 64qam with doppler frequency=30hz original channel estimated predicted 25 30 35 40 10 -6 10 -5 10 -4 10 -3 10 -2 10 -1 10 0 eb/no (db) be r channel estimation and prediction for 256qam with doppler frequency=10hz original channel estimated predicted 25 30 35 40 10 -6 10 -5 10 -4 10 -3 10 -2 10 -1 10 0 eb/no (db) be r channel estimation and prediction for 256qam with doppler frequency=20hz original channel estimated predicted abeer o. al-shammari al-khwarizmi engineering journal, vol. 8, no. 2, pp 84 96 (2012) 94 fig. 16. ber performance of adaptive system. fig. (17) shows the spectral efficiency throughput for estimated and predicted rayleigh fading channel taken over ber threshold 10-4 and doppler frequency shift fd =20 hz and 40 hz. it is clear that when the doppler frequency increases the channel estimation alone fails to track the channel variations, and hence low spectral efficiency, while channel prediction is much more efficient with high spectral efficiency. fig. 17. throughput of predicted and estimated channel fd=20hz, and 30hz ber=10 -4 . 0 5 10 15 20 25 30 10 -6 10 -4 10 -2 10 0 ebno (db) b e r adaptive modulation (mqam) over rayleigh fading channel fd=20hz qpsk 16qam 64qam 256qam adaptive system 15 20 25 30 35 40 4 5 6 7 8 snr db th ro u g h p u t b /s /h z throughput at ber=0.0001 and doppler frequency=20hz original channel estimated channel predicted channel 15 20 25 30 35 40 4 5 6 7 8 snr db th ro u g h p u t b /s /h z throughput at ber=0.00001 and doppler frequency=30hz original channel estimated channel predicted channel abeer o. al-shammari al-khwarizmi engineering journal, vol. 8, no. 2, pp 84 96 (2012) 95 6. references [1] eric phillip, adaptive techniques for multiuser ofdm, ph.d. thesis in electrical and computer engineering, school of engineering, james cook university, december/2001. [2] andrea goldsmith, wireless communications, by cambridge university press, 2005. [3] andrea j. goldsmith and soon-ghee chua, variable-rate variable-power mqam for fading channels, ieee transactions on communications, volume 45, no. 10, october/1997. [4] sang wu kim, adaptive rate and power ds/cdma communications in fading channels, ieee communications letters, volume 3, no. 4, april/1999. [5] thanh thi ngoc do, improving performance of wireless communication systems using adaptive space-time scheme, international symposium on electrical & electronics engineering, hcm city, vietnam, october/24-25/2007. [6] siavash m. alamouti, a simple transmit diversity technique for wireless communications, ieee journal on select areas in communications, volume 16, no. 8, october/1998. [7] a.o. kadhim “ channel estimation and prediction based adaptive communication” msc. thesis, information eng. al-nahrain university 2010 [8] t. s. rappaport, wireless communications: principles and practice, 2nd edition, by prentice hall, 2002. [9] alexandra duel-hallen, shengquan hu, hans hallen, long range prediction of fading signals: enabling adaptive transmission for mobile radio channels, ieee signal processing magazine, may/2000. [10] shengquan hu, alexandra duel-hallen, hans hallen, adaptive modulation using long range prediction for flat rayleigh fading channels, in proc. 2000 ieee int. symp. inform. theory, sorrento, italy, p. 159, june/2000. [11] p. p. vaidyanathan, the theory of linear prediction, by morgan & claypool, 2008. [12] mathieu lagrange, sylvain marchand, martin raspaud, and jean-bernard rault, enhanced partial tracking using linear prediction, proc. of the 6th inernational conference on digital audio effects (dafx-03), london, uk, september/811/2003. [13] tung-sheng yang, performance analysis of adaptive transmission aided by long range channel prediction for realistic singleand multi-carrier mobile radio channels, ph.d. thesis in electrical engineering, north carolina state university, 2004. [14] m. h. hayes, statistical digital signal processing and modeling, by john wiley & sons, 1996. 2012)) 84-96، صفحة2، العدد 8مجلة الخوارزمي الهندسية المجلد عبير عبيد كاظم 96 تخمين ألقناة ألغراض أألتصاالت ألالسلكية ألمتكيفة ***محمد أحمد المشهداني **خليفة عبود سالم د كاظم* يعبير عب ا/ العراق*دائرة تكنولوجيا المعلومات/ وزارة العلوم والتكنولوجي * جامعة بغداد كلية الهندسة الخوارزمي/ /واالتصاالت هندسة المعلوماتقسم جامعة النهرين /كلية تكنولوجيا المعلومات /واالتصاالتالمعلومات قسم هندسة ** الخالصة عة ارسال غرض تغيير سرليانات. يعتبر التضمين المتكيف احد التقنيات الكفوءة لتحقيق التوازن بين سعة القناة ومقدار نسبة الخطأ الحاصلة في ارسال الب ن اداء اللها. وجد اخناة من البيانات فأنه يتطلب معرفة حالة القناة عند جهة االرسال.ان المنظومة المقترحة تتضمن ارسال رموز معروفة لتخمين حالة الق يعطي نتائج جيدة بسبب ان ( فان تخمين القناة ال30hzالمنظومة يكون جيدا في الحاالت التي يكون فيها تردد دوبلر قليل، ولكن عند زيادة تردد دوبلر)< ادمة من خالل قناة لفترة قحالة الالتخمين ال يستطيع مالحقة التغييرات المتسارعة للقناة والتي تحدث بسبب معامالت االضمحالل. لذلك تم اللجوء الى التنبؤ ب .32qamدام عند استخ 10-4 =لخطأ المستهدفة ديسيبل مقارنة بحالة التخمين ونسبة ا 2التنبؤ الخطي ووجد بأنه يعطي تحسين مقداره اكبر من (received 8 march 2011; accepted 9 january 2012) final ammar j. mohammed /al-khwarizmi engineering journal ,vol.1, no. 1,pp 125-133 (2005) ١٢٥ al-khwarizmi engineering journal al-khwarizmi engineering journal, vol.1, no.1,pp 125-133, (2005) kinetic and mechanism of oxidation of oxalic acid by cerium (iv) dr. ammar j. mohammed biochemical engineering dept./,al-khwarizmi engineering college/ university of baghdad abstract: kinetic and mechanism studies of the oxidation of oxalic acid by cerium sulphate have been carried out in acid medium sulphuric acid. the uvvis. spectrophotometric technique was used to follow up the reaction and the selected wavelength to be followed was 320 nm. the kinetic study showed that the order of reaction is first order in ce(iv) and fractional in oxalic acid. the effect of using different concentration of sulphuric acid on the rate of the reaction has been studied a and it was found that the rate decreased with increasing the acid concentration. classical organic tests was used to identify the product of the oxidation reaction, the product was just bubbles of co2. keyword: cerium(iv), kinetics, oxidation, oxalic acid. introduction: cerium element is considered as one of the most spread lanthanides elements. it has numerous oxidation cases (+4, +3, +2) [1]. ce(iv) ion is considered as one of important oxidantes, since its reduction potential was found in sulphuric acid solutions of normality (1-8)n equal 1.44 v. this potential value is different according to the difference of acidic media which contains [2]. ce(iv) solution in acidic media is a stable for long time and is not influenced by light and increasing temperatures for short time [3]. therefore the ce(iv) solution in acidic media is considered as ideal oxidant in oxidation reaction. thus ce(iv) solution in acidic media had region been used as oxidant to oxidize many organic compounds [4-7], such as carboxylic acids [8]. but there was no results reported for oxidation of dicarboxilic acid by ce(iv) except malonic acid [9]. ce(iv) ion in sulphuric acid solution gives absorption peak in ultra violate at 320nm in which ce(iv) ion consumption can be followed up. experimental: 1materials: cerium (iv) sulphate supplied by riedel-dehean of 96% purity, oxalic acid supplied by fluka of 99% purity, sulphuric acid supplied by bdh of 98% purity and double distillated water had been used. method: the reaction was followed up throughout consuming the concentration of ce(iv) ion through tracing decreasing absorption of ce(iv) ion in ultra violate absorption area at wavelength (320)nm. the reaction was carried out by adding 2.5 ml of ce(iv) solution of different concentrations in quartz cell (1×1)cm and adding 100 µl of different concentrations oxalic acid solutions. the absorption was recorded directly after mixing the materials quickly. then, the absorption was determined in successive intervals. the reaction was carried out in. different acidic media of sulphuric acid, as shown in table (1). ammar j. mohammed /al-khwarizmi engineering journal ,vol.1, no. 1,pp 125-133 (2005) ١٢٦ results and discussion: 1kinetic measurement: the kinetic of oxidation of oxalic acid by ce(iv) was studied under 25c° in different concentrations acid media of sulphuric acid and by using different concentrations of the reacting materials. the kinetic study showed that the reaction was pseudo first order under condition [ce(iv)]<<[oxalic acid] by using the absorption as function for the concentration in first order equation: ktaainaain ot −−=− ∞∞ )()( where a∞, ao, at are absorption at the end of reaction, absorption before reaction started, and absorption at particular time respectively. the results showed that the values of rate constant for the first order remained constant at changing the concentration of ce(iv) with constant of other parameters, as it is shown in table (1), fig.1. this indicates that the reaction is first order with respect to ce(iv). rate constant of first order was found it increase by increasing concentration of oxalic acid at constant of other parameters, as it shown in table (1) and fig.2. to find out order of reaction with respect to oxalic acid, log of observed rate constant (kobs) was plotted against log of oxalic acid concentration as shown in fig.3. the relation was linear with a slope 0.66, this value represents order of reaction with respect of oxalic acid. kinetic study showed that the first order rate constant decrease by increasing of sulphuric acid concentration, as it is shown in table (1) and fig.4. log observed rate constant (kobs) was plotted against log (h2so4), as it is shown in fig.5. the relation was linear with a slope-1.03, this value represents the effect of sulphuric acid concentration on the rate of reaction. the relation was linear with a slope 0.66, this value represents order of reaction with respect of oxalic acid.kinetic study showed that the first order rate constant decrease by increasing of sulphuric acid concentration, as it is shown in table (1) and fig.4. 2stoichmetery: stoichmetric measurements, by iodometric titration, showed that each mole of oxalic acid reacts with 2 moles of ce(iv). 3-identification of product: literature showed that the product of oxidation of malonic acid(9), methyl malonic acid(10) and glyoxylic acid(12) by ce(iv) was formic acid with release of co2. in this research, co2release was only observed, and the product of oxidation was not carboxylic acid, no change observed when adding sodium bicarbonate to oxidation product. thus as it is expected the oxidation product of oxalic acid by ce(iv) was just co2. 4-mechanism suggested and concluding law of rate reaction: depending on kinetic measurements, stoichmetric measurements and identification of product, general equation for reaction was suggested as follows: ↑++→+ + 222)(2)(2 cohiiiceivcecooh cooh the following is the mechanism suggested for reaction: ammar j. mohammed /al-khwarizmi engineering journal ,vol.1, no. 1,pp 125-133 (2005) ١٢٧ . )( )( 1           ⇔+ ivce cooh cooh ivcecooh cooh k . ..(1) )( )( 2 iiicehcooh coo ivce cooh cooh slow k ++       + • → . .. (2) coo o c-o cooh c-o-+h+ ..(3) o o c-o o o c-o c o+c o ..(4) o o o • c -o-+ce(iv) c o+ce(iii) ..(5) basing on earlier explanation, law of reaction rate was found out as follow: ] [1 ] )][([)( 1 21 acidoxalick acidoxalicivcekk dt ivdce + =− ..(6) supposing that the reaction was first order: )]([ )]([ ivcek dt ivced obs=− ..(7) compare (6) with (7): ] [1 ] [ 1 21 acidoxalick acidoxalickk kobs + = ..(8) 221 1 ] [ 11 kacidoxalickkk obs += ..(9) with using michaleis menten plot as shown in fig.6, the plot gave linear relation, this proved correctness of the law of reaction rate and mechanism suggested. 5-effect of sulphuric acid on reaction rate: literature showed that − 342 )(soceh was active species resulted from solving ce(iv) in sulfuric acid (11): −⇔+ 3424224 )()( socehsohsoce ..(10) ]][)([ )( * 4224 342 sohsoce soceh k − = ..(11) ][* )( ])([ 42 342 24 sohk soceh soce − = ..(12) substituting ce(so4)2 from (12) to (6) ] ]])[ [1(* ] [)([)]([ 421 34221 sohacidoxalickk acidoxalicsocehkk dt ivced + =− − ..(13) the last equation that clarifies the negative effect of sulfuric acid on reaction rate agrees with experimental results. ammar j. mohammed /al-khwarizmi engineering journal ,vol.1, no. 1,pp 125-133 (2005) ١٢٨ references: 1. j.e.huheey, "inorganic chemistry", harper-row (1972). 2. f.a.cotton; g.wilkinson, "advanced inorganic chemistry", jhon wiley. 4th ed, (1988). 3. g.nagy; e.koros; n. of tedal; k.tjelfhat; p. ruoff, "effect of temperature in cerium-ion catalyzed bromate-driven oscillators", chemical physics letters, 250 (1996) 255-260. 4. r.dayal; g.v.bakore, "kinetics of the oxidation of mandelic acid by cerium (iv) sulphate", j.indian chem. soc., 49 (11), (1972) 10931095. 5. r.g. varma; r.l. yadav, "ceric – cerium oxidation of ortho-cersol", j. indian chem. soc., lx (1983) 554-556. 6. t. tzedakis; a.j. savall, " ceric sulphate oxidation of pmethoxytoluene: kinetics and reaction results", ind. eng. chem. res., 31(11), (1992) 2475-2483. 7. d.c.bilehal; r.m.kulkarni; s.t. nandibewoor, "kinetics of oxidation of pyridylmethylphinybenzimidazole by cerium (iv) in an aqueous perchloric acid medium", turk. j. chem., 27(2003) 695-702. 8. b.singh; p.kumar; r.k.shukla; b.krishna, "kinetics of ce(iv) oxidation of 3-bromo propionic acid in aqueous nitric acid solution", j.indian chem.soc., liv (1977) 378-380. 9. b.neumann; o.stenbock; s.c.muller; n.s.dalal, "stoichiometric fingerprinting as an aid in understanding complex reaction : the oxidation of malonic acid by cerium (iv)", j.phys. chem, 101 (1997) 2743-2745. 10. p.o.kvernberg; e.w.hansen; b.pedersen; a.rasmussen; p.ruoff; "oxidation of methylmalonic acid by cerium (iv). evidence for parallel reaction pathways", j.phys. chem. a, 101 (1997) 2327-2331. 11. p.k.saxena; b.singh; r.k.shuka; b.krishna, "kinetics of ce(iv) oxidation of diethy ketone in sulphuric acid solutions", j.indian chem. soc., lv(1978) 56-59. 12. b.neuman; o.s.stefan; s.c.muller; n.s.dalal, "oxidation of glyoxylic acid by cerium (iv)", j.phys. chem., 100(1996) 1234212348. 13. ammar j. mohammed /al-khwarizmi engineering journal ,vol.1, no. 1,pp 125-133 (2005) ١٢٩ table (1)the values of concentration of reactors and rate constant 104[ce(iv)]/m 102[oxalic]/m [h2so4]/m kobs/min-1 0.3125 0.625 1.25 2.5 5 3.8 0.125 1.41 1.42 1.42 1.35 1.41 1.25 0.24 0.48 0.96 1.9 3.8 0.125 0.276 0.396 0.768 1.188 1.42 1.25 3.8 0.125 0.25 0.5 1 1.42 0.726 0.36 0.166 ammar j. mohammed /al-khwarizmi engineering journal ,vol.1, no. 1,pp 125-133 (2005) ١٣٠ -5 -4 -3 -2 -1 0 1 2 0 10 20 30 40 50 60 70 80 90 time (min) i ii iii iv v ln(at-a∞) 104[ce4+]/m i=5 ii=2.5 iii=1.25 iv=0.625 v=0.3125 ln(at-a∞) -3 -2.5 -2 -1.5 -1 -0.5 0 0 45 90 135 180 225 270 315 360 405 time (min) figure (1) -3 -2.5 -2 -1.5 -1 -0.5 0 0 30 60 90 110 140 170 200 230 260 time (min) -3 -2.5 -2 -1.5 -1 -0.5 0 0 20 40 60 80 100 120 140 160 180 time (min) ln(at-a∞) 103[oxalic]/m i=2.4 ii=4.8 iii=9.6 ln(at-a∞) figure (2) ammar j. mohammed /al-khwarizmi engineering journal ,vol.1, no. 1,pp 125-133 (2005) ١٣١ -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 -2.6 -2.4 -2.1 -1.7 -1.4 log [oxalic acid] log kobs s=0.66 figure (3) -3 -2.5 -2 -1.5 -1 -0.5 0 0 2 4 6 8 10 12 14 time (min) ln(at-a∞) -3 -2.5 -2 -1.5 -1 -0.5 0 0 50 100 150 200 250 300 350 time (min) ln(at-a∞) [h2so4]/m i=0.25 ii=1 iii=0.5 -3 -2.5 -2 -1.5 -1 -0.5 0 0 30 60 90 110 140 170 200 time (min) ln(at-a∞) iii i ii figure (4) ammar j. mohammed /al-khwarizmi engineering journal ,vol.1, no. 1,pp 125-133 (2005) ١٣٢ -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 -0.91 -0.61 -0.3 0 s= -1.03 log kobs figure (5) log [h2so4] 0 1 2 3 4 25 50 100 205 410 s=0.007 i=0.546 1/[oxalic] figure (6) 1/ kobs ammar j. mohammed /al-khwarizmi engineering journal ,vol.1, no. 1,pp 125-133 (2005) ١٣٣ حركية وميكانيكية اكسدة حامض االوكزاليك بواسطة السيريوم الرباعي عمار جاسم محمد.د جامعة بغداد/وارزميخكلية هندسة ال/قسم هندسة الكيمياء االحيائية :الخالصة مت تقنیة االشعة استخد. تم دراسة حركیة ومیكانیكیة اكسدة حامض االوكزالیك في الوسط الحامضي من حامض الكبریتیك بینت الدراسة الحركیة ان التفاعل من المرتبة االولى . nm 320المرئیة لمتابعة التفاعل عند الطول الموجي فوق البنفسجیة .بالنسبة للسیریوم الرباعي والمرتبة الكسریة بالنسبة لحامض االوكزالیك اعل ووجد ان سرعة التفاعل تقل بزیادة تركیز حامض الكبریتیك تم تم دراسة تأثیر تغییر تركیز حامض الكبریتیك على سرعة التف استخدام الكشوفات العضویة االولیة لتشخیص ناتج االكسدة ووجد ان ناتج التفاعل ھو عبارة عن فقاعات غاز ثاني اوكسید .الكاربون human face recognition using wavelt network1 dr. tarik zeyad/al-khwarizmi engineering journal, vol.1, no. 2,pp 14-21 (2005) 14 al-khwarizmi engineering journal al-khwarizmi engineering journal, vol.1, no.2,pp 14-21, (2005) human face recognition using wavelet network dr. tarik zeyad electrical engineering department/ college of engineering/ university of baghdad (received 6 march 2005; accepted 2 october 2005) abstract: this paper presents a study of wavelet self-organizing maps (wsom) for face recognition. the wsom is a feed forward network that estimates optimized wavelet based for the discrete wavelet transform (dwt) on the basis of the distribution of the input data, where wavelet basis transforms are used as activation function. keywords: discrete wavelet transform, wsom, back propagation. 1. introduction face recognition may seem an easy task for humans, and yet computerized face recognition system still cannot achieve a completely reliable performance. the difficulties arise due to large variation in facial appearance, head size, orientation and change in the environment conditions. such difficulties make face recognition on of the fundamental problems in pattern analysis. in recent years there has been a growing interest in machine recognition of faces due to potential commercial applications such as film processing, law enforcement, person identification, access control systems, etc [1]. a complete human face recognition system should include three stages. the first stage involves detecting the location of face in arbitrary images. the second stage requires extraction of pertinent features from the localized image obtained in the first stage. finally, the third stage involves classification of facial images based on the derived feature vector obtained in the previous stage. in order to design a high accuracy recognition system, the choice of the feature extractor is very crucial. two main approaches to feature extraction have been extensively used in conventional techniques. the first one is based on extracting facial features that are local structure of the face images, for example, the shapes of eyes, nose and mouth. the structured based approaches deal with local information instead of global information. therefore, they are not affected by irrelevant information in an image. it has been shown that the structured based approaches by explicit modeling of facial features have been troubled by the unpredictability of face appearance and environmental conditions. the second one is based on statistical approaches when features are extracted from the whole image and therefore use global information instead of local information. since the global data of an image are used to determine the feature elements, data that are irrelevant to facial portion such as hair, shoulders and background may contribute to creation of erroneous feature vectors that can affect the recognition results. dr. tarik zeyad/al-khwarizmi engineering journal, vol.1, no. 2,pp 14-21 (2005) 15 2.neural network a neural network is a set of processing elements, analogous to neurons in brain, connected in a multilayer fashion to perform processing of input data vectors. they were originally described in physiological research on the brain, and were later implemented to solve classification problems. typically, a neural network consists of neurons connected in several layers: one input layer, one output layer and one or more “hidden” layers. at each layer, the neuron forms a weighted sum of all of the outputs of the previous layer and transforms the sum through a nonlinear function called a “squashing” function (often a “sigmoidal” function such a tanh{}) since it tens to compress the output data to avoid truncation. in a classification application, the outputs of the final layer are compared and the class identified with the largest output assigned [1]. the knowledge in the neural net is contained in the weights used to create the sums at the various neurons. these weights are calculated by training process labeled data. the most common method is “backpropagation” in which the weights are iteratively adjusted based on their contribution to the output vector (computed using its partial derivatives) until all input vectors produce the desired outputs. 3.introduction to wavelet transforms transforms are mathematical analysis in different spaces. these transforms can be applied to signals or images to get another aspect of information in the different domain. there are many kinds of transformation methods such as fourier transform, laplace, hough, z, hilbert, ..etc. wavelet transform is a mathematical function that decomposes in terms of time domain. we can analyze each component with a resolution method to its scale. why wavelet transform fourier transform can change data from time domain to frequency domain. mathematical expressions for continuous and discrete fourier transforms are described as follows: o/p1 o/p2 o/p3 output layer hidden layer input layer two layer network o/p output layer hidden layer 2 hidden layer 1 input layer three layer network figure (1): neural network with one and two hidden network. dr. tarik zeyad/al-khwarizmi engineering journal, vol.1, no. 2,pp 14-21 (2005) 16 ∫= r -jωj dtf(t)e)f(ω (1-d continuous ft) dxdye)y,x(f f(u,v) vy)j(ux r +−∫∫= 2 (2-d continuous ft) ∑ ∈ ω−=ω zn nje)n(f)(f (1-d discrete ft) ∑ ∑ ∈ ∈ +ω−= zn zm )mn(je)m,n(f)v,u(f (2-d discrete ft) according to the above equations, one can only analyze either time domain data or frequency data at a time when using fourier transform. however sometimes one needs to analyze time and frequency domain at the same time for non-stationary data (most of natural images and signals). for example, the abrupt change in the ecg frequency signal, which cannot be, analyzed adequately by the fourier transform. as a result, another approach to complement the original fourier transform was suggested, called the short time fourier transform (stft) or windowed fourier transform (wft). for one-dimensional continuous transform, the following is the stft mathematical expression. it can be seen from the above equation that it is a windowed function (transform). however, one does not know the exact time information. he can only know the time interval. so, the wider window produces poorer frequency and better time information. on the other hand, the narrower windows offer better frequency and poorer time resolution. to solve this problem one can use the wavelet transform. wavelet self organizing maps self-organizing maps are a form of unsupervised learning. they are modeled on the fact that similar data is spatially organized in brain. in som n-dimensional, pattern space is mapped on to a single or twodimensional output space. it can also be viewed as a nonlinear projection of the multi-dimensional input space onto a twodimensional output space. wavelet self-organizing maps are feed forward networks having four layers as shown in figure (2). the first layer is the input layer. the second layer is the som competitive learning algorithm [1], which quantizes and maps the input a to an n-node grid. the som layers maps on to the wavelet layer through an n×n matrix d. every node in the wavelet layer has a discrete wavelet function associated with it. each of b1………...bi………..bm o1…………oi……….om y1…………yi………..ym a1………….ai………..am output wavelet som input figure (2) the wsom network. dr. tarik zeyad/al-khwarizmi engineering journal, vol.1, no. 2,pp 14-21 (2005) 17 these functions is encoded by the elements of the matrix d. using the inverse wavelet transform the elements of the d matrix can be calculated. the activation of each wavelet unit plots a piecewise constant function at a particular scale, as the som nodes are successively activated. in case of a one-dimensional input space, the number of wavelet units is the sum of the geometric progression 1+1+2+..+2r-1 = 2r = n[1]. an approximation for the basis for the l2 functions of the input space is given both by the som layer and the wavelet layer. now as the data is preprocessed by the som layer. the wavelet used in this approximation gets adapted to the distribution of the training data. the wavelet bases, so formed by the wsom layer, retain many of the properties of the mother wavelet, including orthogonality, as the wavelets are defined in the grid coordinate of the som layer instead of the co-ordinate of the input space. conventional ways of computing wavelet coefficients require that the input signal be stored in memory, and the wavelet coefficients, by looking at one observation at a time and computing the coefficients using the data rule. the number of coefficients of the wsom layer is lesser than the number of inputs. in this case, the wsom layer uses low-dimension wavelets to form bases for high dimensional input space. the wsom systems have a few advantages over the som, though they have the same root mean square error. the representation of a function using wsom requires lesser number of nonzero weights, and it supports methods for reducing the noise and recovering the signal. the following algorithm implemented the wsom [1]. variables: a? (a1……. ai……am) is the input vector. y? (y1…….yi ……ym) is the vector of activity of the som layer. o? (o1……oi…….om) is the vector of activity of the wavelet layer. b? (b1…….bi…….bm) is the vector of neural output. wj? (w1j…..wij……wmj) is the vector of weights from the input layer to the jth node of the som layer. ds? (d1s……dij…….dmj) is the non-adaptive weights from the som layer to the sth node of the wavelet layer. ck? (c1k……cik…….cmk) is the vector of the weights from the wavelet later to the kth node of the output layer. xj? is the position of the jth unit in the som layer on an integer-valued grid. parameters: a: is the learning rate for weights csk. β: is the learning rate for the weights wij. s: is the neighborhood size used in the som algorithm. j: is the index of the wining unit at the som layer. hij decrease the complexity with the distance to the jth unit in the som layer. wand w+ are the minimum and the maximum of initial weights wij. β0 is the initial value for β. β1 is the final value for β. s0 is the initial value for s. s1 is the final value for s. dr. tarik zeyad/al-khwarizmi engineering journal, vol.1, no. 2,pp 14-21 (2005) 18 t1 is the required training sets to decrease β and s from β0 and s0 to β1 and s1 respectively. n: is the total training set input number. algorithm 1-set t=1, csk’s=0 and evenly distribute the weights wij’s in [w-,w+]. 2-decrease β:     = <     = − − 11 1 1 1 1 0 0 1 t if t β tt if β βββ t t 3-decrease s:     = <     = − − 11 1 1 1 1 0 0 1 t if t s tt if s sss t t 4-obtain the jth input vector a, and the output vector b. 5-find j=arg minj║a-wj║. 6-calculate the activity of the som layer: yj=1 and yj=0. 7-calculate the activity of the wavelet layer: f=dy=djs. 8-compute the output ∑ = = n s sskk ocβ̂ 1 . 9-adjust csk according to ( )kkssk β̂βαoδc −= . 10-set         − = 2 2 s xx exph jj jj . 11-adjust wik according to : )wa(hw ikikjjikik −β=∆ . 12-if t=n, then stop, else go to step 1 with (t=t+1). 4. wavelet neural networks a wavelet neural network (wnn) shown in figure (3), is a network layer with two layers whose output nodes form a linear combination of wavelet basis functions that are calculated in the hidden layer of the network. the basis used in wnn has been given the name “wavelons” [3]. these wavelons produce a localized response for an input impulse. that is, they produce a non-zero output when the input lies within a small area of the input space. o o o σ 1 x1 x2 xn g(x) w0 w1 w2 wn hidden layer figure (3): the proposed wavelet network. dr. tarik zeyad/al-khwarizmi engineering journal, vol.1, no. 2,pp 14-21 (2005) 19 the wavelet orthonormal basis is a set of functions formed by the scaling and translating the “mortlet” mother wavelets are used to decompose the input signal under analysis. this introduces an additional layer in neural network model. this layer is modified while the teaching process is in progress. the properties of wavelet transform emerging from a multi-scale decomposition of signals [4], allow the study of both stationary and nonstationary signals. on the other hand the neural network performs a stationary analysis of nonlinear as well as linear dependencies due to different possible structures and activation function. the neurons of the hidden layer in a neural network have wavelet activation functions of different resolutions. wavelets are used as activation functions in locally responsive units. a wavelet network formed is formed on the basis of appropriate basis functions. once created, it has the capability of the approximating any continuous nonlinear mapping to any high resolution. a simple wavelet neural network displays a much higher level of generalization and shorter computing time as compared to a three-layered feed forward neural network. 5. the phases of recognition process the recognition process contains two phases. the first phase is the twelve different faces were used during the learning phase of the recognition process. each face provides the learning process with a twelve elements data vector used as the input of the learning wnn and this vector is used to calculate the weights of the wavelet network. the data vector represents the intensity of eight different points in the face plus the distance between the two eyes, the distance between the two ears, the distance between the end of the nose and the mouth and finally the total length of the face. these distances were all normalized according to the total number of pixels that represents the face. this normalization process is made in order to have a scale independent recognition process. the second phase of the recognition process was the test phase. in this phase the pictures of the twelve different faces used in the test with angle of rotation up to 40%. the recognition process gives correct results up to 30% rotation. between 30% and 40% rotation percent only two of the pictures give correct results. 6. discussion in this paper the co-existence of neural networks and the wavelets is briefly discussed and it is seen how the neural network assist choosing the optimal shape of the wavelet. the recognition process gives good results with a good degree of face rotation but not more than 30% degree of face rotation. 7. references 1-carpenter, g. a., “wsom: building adaptive wavelets with selforganizing maps”, the 1998 ieee international joints conference, vol. 1, pp. 763-767. 2-dongwook, c., “face recognition system based on wavelet transform”, department of computer science, concordia university, 2003. 3-po-rong, c., bao, f., “nonlinear computation channel equalization using wavelet neural networks”, the ieee international conference on computational intelligence, vol. (6), pp. 36o5-3610, 1994. 4-kostka, p., tkacz, e. j., naeral, z., and malota, z., “an application of wavelet neural network (wnn) for heart value prostheses dr. tarik zeyad/al-khwarizmi engineering journal, vol.1, no. 2,pp 14-21 (2005) 20 characteristics”, ieee, engineering in medicine and biology society, vol. (4), pp. 2463-2465, 2000. 5-vetterli, m. and herely, c., “wavelets and filter banks: theory and design”, 2003. the ieee international conference on computational intelligence, vol. (6), pp. 2207-2232, 1994. dr. tarik zeyad/al-khwarizmi engineering journal, vol.1, no. 2,pp 14-21 (2005) 21 تمييز الوجه البشري باستخدام تحويل المويجة طارق زياد.د كلیة الھندسة/قسم الھندسة الكھربائیة جامعة بغداد :الخالصة باستعمال التحويل المويجي مع الشبكات العصبية هتم في هذا البحث بناء منظومة لتمييز األوج هذا النوع من الشبكات تتعامل مع التحويل المويجي المتقطـع كمصـدر . من النوع ذات التنظيم الذاتي لها الشبكة حيث يتم استعمال مكونات تحويل المويجة كدوال تحفيز فـي داخـل للبيانات التي يتم إدخا .الشبكة اميل وشذى واسيل al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 10, no. 2, p.p. 114 (2014) prediction of oxygen mass transfer coefficients in stirred bioreactor with rushton turbine impeller for simulated (non-microbial) medias ameel mohammed rahman al-mayah* shatha kadhum muallah** aseel abd al-jabbar*** *,**,***department of biochemical engineering/ al-khawarizmi college of engineering/ university of baghdad *e-mail: drameel@kecbu.uobaghdad.edu.iq **e-mial: shatha_engr@yahoo.com ***e-mial: aseel_133@yahoo.com (received 12 january 2013; accepted 18 may 2014) abstract the study of oxygen mass transfer was conducted in a laboratory scale 5 liter stirred bioreactor equipped with one rushton turbine impeller. the effects of superficial gas velocity, impeller speed, power input and liquid viscosity on the oxygen mass transfer were considered. air/ water and air/cmc systems were used as a liquid media for this study. the concentration of cmc was ranging from 0.5 to 3 w/v. the experimental results show that volumetric oxygen mass transfer coefficient increases with the increase in the superficial gas velocity and impeller speed and decreases with increasing liquid viscosity. the experimental results of kla were correlated with a mathematical correlation describing the influences of the considered factors (the overall power input and the superficial gas velocity) over the studied rages. the predicted kla values give acceptable results compared with the experimental values. the following correlations were obtained: air/water system ( ) v v p ak g l g l 43.1 088.0 4.30       = air/cmc system (0.5w/v ) ( ) v v p ak g l g l 3.2 06.0 522       = air/cmc system (1w/v ) ( ) 811 3.2 06.0 g l g l v v p ak       = air/cmc system (2w/v ) ( ) 1623 3.2 06.0 g l g l v v p ak       = air/cmc system (3w/v ) ( ) 1576 3.2 06.0 g l g l v v p ak       = keywords: stirred bioreactor; oxygen mass transfer coefficient; superficial air velocity; rushton turbine impeller. mailto:shatha_engr@yahoo.com mailto:aseel_133@yahoo.com ameel mohammed rahman al-khwarizmi engineering journal, vol. 10, no. 2, p.p. 114 (2014) 2 1. introduction in many chemical (e.g. hydrogenation, chlorination) and biochemical industries (e.g. aerobic fermentation), the transfer of gas molecules from swarm of bubbles into turbulent liquid medium play an important role. in fermentation industries, e.g. yogurt, beer, yeast, wine and countless pharmaceutical products are widespread and provide many everyday consumer products. these industries involve the use of microorganism to convert the biomass into a quality product with high yield (zadghaffari et al, 2009; najafpour, 2007; muhd, 2005; meenal et al., 2005; galaction et al., 2004). understanding of all the processes may require basic knowledge of biology, biochemistry, biotechnology, and real knowledge of engineering processes (cascaval d. et al., 2004; priede et al., 2002; vilaça et al., 2000). in aerobic fermentation, the activities of microorganisms are monitored by the utilization of oxygen from the supplied air and the respiration quotient. the primary and secondary metabolites in a bioprocess can be estimated based on projected pathways for production of intracellular and extracellular by-products (felix et al., 2009; ikram-ul, et al., 2005; le´on et al., 2001). oxygen transfer is often the limiting step that controls the aerobic system (felix et al., 2009; ladislav, 1999). the amount of dissolved oxygen in the reaction medium is limited by the solubility and mass transfer rate, and as well as by its consumption rate on cell metabolic pathways (davis et al., 2010; felix et al., 2009; ghaly et al., 2003). transport characteristics are function of many parameters, the most important parameter affecting the design and the operation of the unit is the mass transfer coefficient, kla. many factors are known to affect aeration efficiency (kla), including such parameters as agitation, air flow rate, air pressure, temperature, vessel geometry, fluid characteristics (density, viscosity, surface tension, etc.), presence of antifoam agents, the concentration and physical properties of the immobilizing materials (density, particle size, etc.), etc. (aoyi et al., 2008; gimbun et al., 2009; archis et al., 2002; ). the major problem in bioreactor operation and scale–up is the uneven distribution of shear and energy dissipation, which are known to be harmful to the microorganisms in the bioreactors (davis et al., 2010; catapano et al., 2009; scargiali et al., 2007). in order to meet this demand, an agitation system must provide the required transport characteristics at low possible energy consumption (davis et al., 2010; catapano et al., 2009; aoyi et al., 2008). stirred tank and bubble column bioreactors are widely used bioprocesses (as aerobic fermentation and biological wastewater treatments, among others). stirred tank bioreactor provides high values of mass and heat transfer rates and excellent mixing. in this system, a high number of variables affect the mass transfer and mixing, the most important among them are stirrer speed, type and number of stirrers and gas flow rate used. the correct measurement and/or prediction of the volumetric mass transfer coefficient, (kla), is a crucial step in the design, operation and scale-up of bioreactors (catapano et al., 2009). fermentations are carried out in aqueous medium containing salts and organic substances, and these broths usually are viscous. for low viscosity fluids and for microorganisms and product with low shear sensitivity, almost any type of bioreactors can be used, provided it leads to adequate homogeneity and good mass transfer. however, under highly viscous and nonnewtonian conditions, mixing becomes more difficult, and as a result, poor distribution of oxygen and nutrients inside the bioreactor is obtained (najafpour , 2007; muhd, 2005; hélène, 1998). the effects of the homogeneity of the fermentation broth, the oxygen mass transfer rate, the shear stress produced by the mixing element and the ease of scale-up are studied on many workplaces all over the world but no unambiguous answer has been found up to these days. various modifications on operating and geometric parameters were performed to improve the gas-liquid mass transfer. many types of agitator have been used in industry to enhance gas-liquid contact operation. several types of impellers (rushton turbines, paddle, mig, hydrofoils. etc.) are used for highly viscous aerated reactors (paul et al., 2004; mária et al., 2004; david et al., 2003; zhen et al., 2003; tomáš et al., 2003). when viscosity increases, these remote clearance impellers become inefficient because extremely high power must be supplied locally to the fluid by the impeller if enough mixing energy is to reach all parts of the fluid to insure adequate mixing. this problem becomes even more severe if the fluid is nonnewtonian because the viscosity is a function of the shear rate (archis et al., 2002; diaz et al., 1999). although, there are many studies had been done in this area, but the need for further studies ameel mohammed rahman al-khwarizmi engineering journal, vol. 10, no. 2, p.p. 114 (2014) 3 are urgently needed to increase understanding of the bioreactors. the aim of the present work is to examine the volumetric oxygen transfer coefficient kla in a stirred bioreactor using rushton turbine impeller, taking into account the effects of viscosity (for newtonian and nonnewtonian fluid), impeller speed, the superficial gas velocity and the overall power input to medium. 2. power consumption in bioreactors, the energy imparted to the broth by agitator creates uniform distribution of air in the media. the interfacial area increases as a result of reducing air bubble size. therefore the mass transfer coefficient would be a function of power input per unit volume of fermentation broth, which is also affected by the gas superficial velocity (najafpour 2007). 2.1. power consumption in ungassed system the power consumption cannot be predicted theoretically, therefore empirical correlations have been developed to predict the power required. the power consumption in relation to operating variables and geometric parameters data could be grouped to dimensionless groups as power and reynolds numbers given as follows (najafpour 2007): dn pn i o p       = 53ρ …(1) ndi       = µ ρ 2 re …(2) where po = power in ungassed system (w), n = impeller speed (rps), ρ= liquid density (kg/m3), μ = liquid viscosity (newton.sec/m2), and di = impeller diameter (m) the power number was correlated with reynolds number for various impeller geometry and at different regimes. the relation between these two dimensionless groups was presented by log-log figure, (which has been reported by many researchers). the calculation of power number for nonnewtonian fluids in bioreactors is the same as newtonian fluids but the viscosity must be correlated with the apparent viscosity. the apparent viscosity for non-newtonian fluids is not constant varies with the shear rates and velocity gradient in the vessel. in order to do that, an apparent viscosity (μ app) is defined as follows (najafpour 2007; badino et al., 2001; pouliot et al., 2000): k n app γµ = …(3) where μapp = shear stress (n/m2) γ= shear rate (s-1) k = consistency index (pa.s) n = flow behavior index (-) the value of shear rate in bioreactors was determined using metzner and otto equation (najafpour 2007): an=γ …(4) where a = metzner and otto constant (depend on impeller type). it was assume to be 11.5, for rushton turbine. n = impeller speed (rpm). 2.2. power consumption in gassed system the power consumption in agitated gassed systems is less than for ungassed systems. the apparent viscosity and density decreases with increasing agitation upon gassing. prediction of power consumption (pg) in a stirred tank is usually based on well known traditional correlation proposed by michel and miller (najafpour 2007; kumaresan et al., 2006): q ndpmp 0.45 io g       = 56.0 32 …(5) where m= constant depends on impeller type and geometric form (for rushton turbine m=0.832), q = volumetric gas flow rate (m3/s) 3. correlation between mass transfer coefficient and power consumption there are many correlations were proposed that estimate the kla in single and multiple impeller systems for newtonian and nonnewtonian fluids (davis et al., 2010; catapano et al., 2009; wen et al., 2000). kla was correlated with mechanical agitation power per unit volume (pg/vl) and gas sparging rate expressed as the ameel mohammed rahman al-khwarizmi engineering journal, vol. 10, no. 2, p.p. 114 (2014) 4 superficial velocity (vg). the power input per unit volume (pg/vl) and, superficial gas velocity vg are major correlation coefficients for kla. therefore, the following equation is frequently found which proposed by cooper and his coworkers (1944) and used in the literature (davis et al., 2010; zadghaffari et al., 2009; felix et al., 2009; muhd 2005; cascaval et al., 2004). ( ) v v p ak g l g l γ β α       = …(6) where, pg = is the mechanical agitation power (w), vl = liquid volume (m3) vg = gas superficial velocity (m/s), α,= is a constant, β, and γ, are exponents 4. experimental work 4.1. materials distilled water, carboxymethyl cellulose (cmc) (of analytical grads), and nitrogen gas (99.999%) were used in this study. 4.2. bioreactor a 5 liters bench scale bioreactor was used in this study. the bioreactor was filled with 3.75 l of distilled water to be used as a working volume. the details of the reactor geometry and dimensions are given and illustrated in table 1 and fig.1, respectively. six blades rushton turbine impeller was conducted to the driven shaft of the agitator and four baffles were provided. the schematic diagram of the experimental setup was shown in fig.2. the compressed air or nitrogen, fed at the bottom of the bioreactor was sparged through 4 cm diameter circular sparger, with 12 holes of 1 mm diameter. air flow rates were measured and controlled by a rotameter (qvf type, 1500 l/h max.). all experimental runs were carried out at atmospheric pressure and a temperature of 33˚c. a series of experiments were performed in the gas flow rate range from 1 to 20 l/min, impeller speed range from 100 to 1200 rpm, the cmc concentration ranging from 0.5 to 3 w/v. the speed of impeller was controlled using voltage regulator and measured using dt-1236l tachometer type lutron. table 1, dimensions of stirred tank bioreactor. bioreactor total volume, vt (liter) 5 bioreactor working volume, vl (liter) 3.75 bioreactor vessel height, ht (cm) 16 bioreactor vessel diameter, dt (cm) 20 impeller type rushton turbine impeller diameter, (di ) cm 6 no. of impellers 1 impeller thickness, (ti) mm 2 impeller width, (wi ) (cm) 1.3 sparger diameter, cm 4 sparger distance from impeller bottom, cm 2 no. of baffles 4 width of baffles, cm 2 ameel mohammed rahman al-khwarizmi engineering journal, vol. 10, no. 2, p.p. 114 (2014) 5 fig. 1. geometry of stirred tank bioreactor. 4.3. measurement of volumetric mass transfer coefficient the determination of the overall volumetric mass transfer coefficient value of a bioreactor is essential in order to establish its aeration efficiency and to quantify the effect of operating variables on the provision of oxygen. the, kla, was determined by the static gassing method (najafpour, 2010; bouaifi et al., 2001; chisti, 1989). the dissolved oxygen concentration in bioreactor liquid phase was measured by means of an oxygen probe inserted vertically and placed at 2 cm under the liquid level, and connected to a dissolved oxygen-meter type lutron do-5510. the oxygen probe signals were measured using a/d converter and recorder on a pc. in each experimental run, tap water has been first stripped of oxygen by the static gassing method by bubbling n2 gas through the gas sparger. this step will continue till the probe reading becomes zero. after that the nitrogen gas flow was turned off and the flow switched to the air flow with a specific volumetric flow rate using the rotameter then the dissolved oxygen concentration was recorded with respect to time as air is distributed into the bioreactor and until the water became saturated with oxygen. the investigations of mass transfer characteristics were restricted to oxygen transfer only, and in all investigations, the bioreactor systems were subject to the following assumptions (najafpour, 2010; chisti, 1989): gas composition is constant. the system is isothermal, and the effect of the dynamics of the dissolved oxygen electrode is negligible. for sparingly soluble gases such as oxygen, the liquid phase volumetric mass transfer coefficient (kla) is nearly equal in value to that of the overall volumetric mass transfer coefficient (kla). a material balance on dissolved oxygen according to the above assumption gives the following equation (najafpour, 2010; chisti, 1989): ( ) ( ) ooakooak dt do ll −=−= ** …(7) o*: saturation dissolved oxygen concentration. o: dissolved oxygen concentration in liquid phases. integrate eq. (7) with the limits of o = o° at t = 0 and o = o at t = t results in: ∫∫ = − t l o o dtak oo do 0* )(o …(8) the result of integration is atk oo oo l=      − − )( )(ln * * o …(9) the value of kla is obtained from the slope of the linear regression with       − − )( )(ln * * oo oo o with respect to time (t). 4.4. viscosity measurement the actual viscosity of distilled water and water with cmc solutions were measured using viscometer type brookfield model lvdv (3 2000.000 cp). dt ht wi ti di rushton turbine impeller. ameel mohammed rahman al-khwarizmi engineering journal, vol. 10, no. 2, p.p. 114 (2014) 6 fig. 2. experimental setup of stirred bioreactor. 5. results and discussion oxygen transfer in fermentor is the major concern for adjustment in aeration and agitation. in this work a simulation of synthetic fermentation (nonmicrobial) media was made to approximate the situation. the operating conditions were chosen in order to meet the same situation in fermentor. 5.1. effect of superficial gas velocity on the kla values the effect of superficial gas velocity vg on the kla values at different speeds of agitation and liquid viscosities are shown in fig.3 and 4, respectively. it can be observed that, the value of kla increases with an increase in vg. generally, kla values for air/ water system increases from 0.0135 s-1 to 0.048 s-1 when vg increases from 0.053 cm/s to 1.06 cm/s at 400 rpm. this is many be attributed to the fact that at high air flow rate, bioreactor gas holdup increases leading to a high a (bubble surface area) which in tern increases the kla values. the increase in non-newtonian behavior results in changing the properties of liquid. consequently, lower reynolds number in viscous liquid in comparison to newtonian liquid at the same aeration and agitation was obtained. the kla values decreases from 0.0157 to 0.009 s-1 when the liquid viscosity increases from 0.5 to 3 w/v at constant vg of 1.06 cm/s and over the same (400) rpm. this can be observed clearly in fig. 4. also, it can be seen that the increase of cmc concentration results in an increase in oxygen mass transfer resistance from the air bubble to the liquid. 3 1 4 5 6 7 8 9 5 10 11 5 2 1 oxygen probe meter 2 bioreactor 3 gas distributor 4 rotameter 5 valve 6 air compressor 7 interface 8 computer 9 n2 cylinder 10 n2 gas pressure regulator 11 t-join connector 12 agitator 13 stand 13 12 ameel mohammed rahman al-khwarizmi engineering journal, vol. 10, no. 2, p.p. 114 (2014) 7 0 0.02 0.04 0.06 0.08 0.1 0.12 0.000 0.002 0.004 0.006 0.008 0.010 0.012 vg, (m/s) k l a, (s -1 ) rpm=100 rpm=200 rpm=400 rpm=800 rpm=1200 fig. 3. effect of superficial gas velocity on kla for air/water system at different speed of agitation. 0 0.002 0.004 0.006 0.008 0.01 0.012 0.014 0.016 0.018 0.000 0.002 0.004 0.006 0.008 0.010 0.012 vg, (m/s) k l a, () 0.5 (w/v) cmc 1.0 (w/v) cmc 2.0 (w/v) cmc 3.0 (w/v) cmc fig. 4. effect of superficial gas velocity on kla for air/cmc system at cmc concentrations and at 400 rpm. 5.2. effect of impeller speed on the kla values impeller speed is one of the most important factor in bioreactor, it decided the overall power dissipation for any specific impeller geometry. figure 5 and 6 show the relation between impeller speed and kla values for air/water and air/cmc systems. it can be observed that with an increase in the impeller speed, kla values increases from 0.00165 to 0.042s-1, 0.0005 to 0.043s-1, 0.00054 to 0.037s-1, 0.0003 to 0.028s-1, 0.0001 to 0.024s1, for air/water, 0.5, 1, 2, and 3w/v cmc systems, respectively, and over the same air flow rate of 1l/min. this can be attributed to the rapid breakage of the gas bubbles into smaller size with an increase in the impeller speed and thus enhancing the gas-liquid interfacial area for the mass transfer. this also results in a maximum bioreactor gas holdup and hence high values of kla. the same observations were found in other works (meenal et al., 2005; babalona et al., 2005; muhd, 2005; galaction et al., 2004). as the liquid viscosity and impeller speed increases, kla values decreases. this is can be attributed to the same reason that explained in the previous section. consequently, a drop in oxygen transfer rate occurs. the variation in the kla ameel mohammed rahman al-khwarizmi engineering journal, vol. 10, no. 2, p.p. 114 (2014) 8 values attained was consistent with that found in the literature by (ikram-ul et al., 2005; cascaval et al., 2004; badino et al., 2001; wen et al., 2000). 0 0.02 0.04 0.06 0.08 0.1 0.12 0 200 400 600 800 1000 1200 1400 rpm k l a, () vg =0.053 cm/s vg =0.265 cm/s vg =0.477 cm/s vg =0.796 cm/s vg =1.061 cm/s fig. 5. effect of impeller speed on kla values for air/water system at different air flow rates. 0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05 0 200 400 600 800 1000 1200 1400 rpm k l a, () 0.5 (w/v) cmc 1.0 (w/v) cmc 2.0 (w/v) cmc 3.0 (w/v) cmc fig. 6. effect of impeller speed on kla values for air/cmc system at different viscosities and air flow rate of 1 l/min. 5.3. effect of impeller power input on the kla values the effect of the total power input (impeller power and gas expansion) on the volumetric mass transfer coefficient is shown in the figure 7 and 8 for air/water and air/cmc systems, respectively. the increase of specific power input leads to kla increase. at higher aeration rate, the air dispersion is amplified by combined action of mechanical and pneumatic mixing. the highest value of kla was observed for airwater system as compared to air/cmc systems. in general, introducing polymer into the liquid will suppress the turbulence and increase the oxygen transfer resistance. on the other hand, the reduction of polymerlaw, due to polymer presence, lower the gas hold-up and decreases the interfacial area (felix et al., 2009; gimbun et al., 2009; kumaresan et al., 2006; galaction et al., 2004, mária et al., 2004). ameel mohammed rahman al-khwarizmi engineering journal, vol. 10, no. 2, p.p. 114 (2014) 9 0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.1 1 10 100 1000 10000 100000 pg/vl, (w/m3) k l a, () vg =0.053 cm/s vg =0.265 cm/s vg =0.477 cm/s vg =0.796 cm/s vg =1.061 cm/s fig. 7. the effect of specific power input on oxygen mass transfer coefficient for air/water system at different air flow rate. 0 0.0005 0.001 0.0015 0.002 0.0025 1 10 100 1000 10000 100000 pg/vl, (w/m3) k l a, () 0.5 (w/v) cmc 1.0 (w/v) cmc 2.0 (w/v) cmc 3.0 (w/v) cmc fig. 8. the effect of specific power input on oxygen mass transfer coefficient for air/cmc system at different viscosities and air flow rate of l/min. 5.4. correlation for kla at different operational parameters in 5 liter bioreactor the obtained oxygen mass transfer coefficient values with air/water and air/cmc systems were correlated with the impeller speed, liquid viscosity and the superficial gas velocity using eqn. 6. the analysis was performed using statistica software with non-linear regression. table 2 summarizes the final results of theses analysis. from this table, it can be observed that there is no significant effect on the exponents of vg and (pg/vl) over the studied range of cmc concentration. the exponent of vg for air/water system is lower than that for air/cmc system at different concentrations. this is due to good uniform dispersion and mass transfer rate for air/water than air/cmc systems. the predicted and experimental data were presented in fig. 9 to 13. an acceptable result with an average correlation coefficient of 0.95 was obtained. this means that proposed model offers a good agreement with the experimental data. ameel mohammed rahman al-khwarizmi engineering journal, vol. 10, no. 2, p.p. 114 (2014) 10 table 2, correlation constants and nonlinear regression analysis parameters. correlation constants standard deviation correlation coefficient, r2 α β γ air/water system 30.4 0.088 1.43 0.01 0.98 air/cmc system (w/v ) 0.5 522 0.06 2.3 0.019 0.99 1 811 0.06 2.3 0.019 0.99 2 1623 0.06 2.3 0.015 0.99 3 1576 0.06 2.3 0.014 0.99 0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.1 0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.10 kla, experimental value k l a, p re di ct ed v al ue vg =0.053 cm/s vg =0.265 cm/s vg =0.477 cm/s vg =0.796 cm/s vg =1.061 cm/s fig. 9. comparison between the experimental and predicted data from the proposed model and for air/water systems at different air flow rates. 0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07 kla, experimental value k l a, p re di ct ed v al ue vg =0.053 cm/s vg =0.265 cm/s vg =0.477 cm/s vg =0.796 cm/s vg =1.061 cm/s fig. 10. comparison between the experimental and predicted data from the proposed model and for air/cmc systems at 0.5w/v concentration and at different air flow rates. ameel mohammed rahman al-khwarizmi engineering journal, vol. 10, no. 2, p.p. 114 (2014) 11 0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07 kla, experimental value k l a, p re di ct ed v al ue vg =0.053 cm/s vg =0.265 cm/s vg =0.477 cm/s vg =0.796 cm/s vg =1.061 cm/s fig. 11. comparison between the experimental and predicted data from the proposed model and for air/cmc systems at 1w/v concentration and at different air flow rates. 0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07 kla, experimental value k l a, p re di ct ed v al ue vg =0.053 cm/s vg =0.265 cm/s vg =0.477 cm/s vg =0.796 cm/s vg =1.061 cm/s fig. 12. comparison between the experimental and predicted data from the proposed model and for air/cmc systems at 2w/v concentration and at different air flow rates. 0 0.01 0.02 0.03 0.04 0.05 0.00 0.01 0.02 0.03 0.04 0.05 kla, experimental value k l a, p re di ct ed v al ue vg =0.053 cm/s vg =0.265 cm/s vg =0.477 cm/s vg =0.796 cm/s vg =1.061 cm/s fig. 13. comparison between the experimental and predicted data from the proposed model and for air/cmc systems at 3w/v concentration and at different air flow rates. ameel mohammed rahman al-khwarizmi engineering journal, vol. 10, no. 2, p.p. 114 (2014) 12 6. conclusions oxygen mass transfer was evaluated in a 5 liter laboratory bioreactor. evaluation of the experimental data shows that the kla values are affected by factors, such as impeller speed, the superficial air velocity, total power input to the liquid medium, and media viscosity. the the correlations developed in this study more accurately model the data and are useful for the design of 5 l bioreactor. these correlations are as follows: air/water system ( ) 4.30 43.1 088.0 g l g l v v p ak       = air/cmc system (0.5w/v ) ( ) 522 3.2 06.0 g l g l v v p ak       = air/cmc system (1w/v ) ( ) 811 3.2 06.0 g l g l v v p ak       = air/cmc system (2w/v ) ( ) 1623 3.2 06.0 g l g l v v p ak       = air/cmc system (3w/v ) ( ) 1576 3.2 06.0 g l g l v v p ak       = acknowledgement this study was supported by a grant provided by the ministry of higher education and scientific research/ research and development department. authors gratefully acknowledge this contribution and supporting. 7. references aoyi o., maurice s. o., anil k., kirimi k., paul m., (2008), ”mixing in a tank stirred by a rushton turbine at a low clearance”, chemical engineering and processing, no. 47, pp. 842–851. archis a. y., albertus b. m. h., geert f. v. and vishwas g. p., (2002), “gas–liquid mass transfer coefficient in stirred tank reactors”, the canadian journal of chemical engineering, vol. 80, october, pp. 840-848. babalona e., paras s. v., and markopoulos j., (2005) “complete dispersion characteristics in gas-liquid contractors agitated by single and doublestage rushton turbines”, chem. eng. technol., no. 2 pp. 137-139. badino a.c. jr., facciotti m.c.r., and schmidell w., (2001), “volumetric oxygen transfer coefficients (kla) in batch cultivations involving non-newtonian broths”, biochemical engineering journal, no. 8, pp. 111–119 bouaifi, m., hebrard, g., bastoul, d., and roustan, m., (2001), "a comparative study of gas hold-up, bubble size, interfacial area and mass transfer coefficients in stirred gas-liquid reactors and bubble columns", chem. eng. proc., 97-111. cascaval d., anca-irina g., corneliu o., and florina u., (2004), “modeling of mixing in stirred bioreactors 4. mixing time for aerated bacteria, yeasts and fungus broths”, chem. ind. vol. 58, no. 3, pp. 128-137. catapano g., czermak p., eibl r., eibl d., and pörtner r., (2009), “, “cell and tissue reaction engineering: principles and practice, chapter 5: bioreactor design and scale-up”, springerverlag berlin heidelberg. chisti y., (1989), "airlift bioreactors", elsevier applied science, london. david r. nielsen, andrew j. daugulis, p. james mclellan, (2003), “a novel method of simulating oxygen mass transfer in two-phase partitioning bioreactors”, biotechnology and bioengineering, vol. 83, no. 6, pp. 735-742. davis, ryan z., "design and scale-up of production scale stirred tank fermentors" (2010). graduate thesis, utah state university. diaz a., f. acevedo, (1999), “scale-up strategy for bioreactors with newtonian and nonnewtonian broths”, bioprocess engineering no. 21, pp. 21-23. felix g. o. and emilio g., (2009), “bioreactor scale-up and oxygen transfer rate in microbial processes: an overview”, biotechnology advances no. 27, pp. 153–176. galaction a. i., cascaval d., oniscu c., and turnea m., (2004), “prediction of oxygen mass transfer coefficients in stirred bioreactors for bacteria, yeasts and fungus broths”, biochemical engineering journal, no. 20, pp. 85–94. ghaly a. e. and mahmoud n. s., (2003), “heat generated by mechanical agitation and lactose metabolism during continuous propagation of kluyveromyces fragils in cheese whey”, journal of scientific research and development, vol. v, may. gimbun j., rielly c.d., nagy z.k., (2009), “modelling of mass transfer in gas–liquid stirred ameel mohammed rahman al-khwarizmi engineering journal, vol. 10, no. 2, p.p. 114 (2014) 13 tanks agitated by rushton turbine and cd-6 impeller: a scale-up study”, chemical engineering research and design, no. 87, pp. 437–451 hélène g., (1998), “caractérisation d'un bioreacteur à plateaux à mouvement alternatif et son application à la culture de cellules végétales”, m.sc. thesis, université laval. ikram-ul h., sikander a. and qadeer m.a., (2005), “influence of dissolved oxygen concentration on intracellular ph for regulation of aspergillus niger growth rate during citric acid fermentation in a stirred tank bioreactor”, international journal of biological sciences, no.1, pp.34-41. kumaresan t., and jyeshtharaj b. j, (2006), ”effect of impeller design on the flow pattern and mixing in stirred tanks”, chemical engineering journal, no. 115, pp. 173–193. ladislav c., (1999), “mass transfer at mixing processes”, periodica polytechnica ser. chem. eng. vol. 43, no. 2, pp. 77–87. le´on a. de, barba-de la rosa a.p., mayani h., galindo e. & ram´ırez o.t., (2001), “two 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leiva g. a., (2000), “kla evaluation during the course of fermentation using dad reconciliation technique”, bioprocess engineering, no. 23, pp. 565-573. priede m. a., vanags j. j. and viesturs u. e., (2002), “performance of aspergillus niger cultivation in geometrically dissimilar bioreactors evaluated on the basis of morphological analyses”, food technol. biotechnol., vol., 40, no. 1, pp. 57–66. scargiali f., d’orazio a., grisafi f. and brucato a., (2007), “modeling and simulation of gasliquid hydrodynamics in mechanically stirred tanks”, chemical engineering research and design, vol 85, a5, pp. 637–646. tomáš m., václav l., and eva p., (2003), “gas hold-up, mixing time and gas–liquid volumetric mass transfer coefficient of various multipleimpeller configurations: rushton turbine, pitched blade and techmix impeller and their combinations”, chemical engineering science, no. 58, pp. 1839 – 1846. vilaça p. r., badino a. c. jr., facciotti m. c. r., and schmidell w., (2000), “determination of power consumption and volumetric oxygen transfer coefficient in bioreactors”, bioprocess engineering, no. 22, pp.261-265. wen j., na p., huang l., chen y., (2000), “local overall volumetric gas–liquid mass transfer coefficients in gas–liquid–solid reversed flow jet loop bioreactor with a non-newtonian fluid”, biochemical engineering journal, vol. 5, pp. 225–229. zadghaffari r., moghaddas j.s., revstedt j., (2009), “a mixing study in a double-rushton stirred tank”, computers and chemical engineering, no. 33, pp. 1240–1246. zhen h., anurak p. and warawitya m., (2003), “oxygen-transfer measurement in clean water”, the journal of kmitnb., vol. 13, no. 1, pp. 1419. )2014( 114، صفحة 2، العدد10دجلة الخوارزمي الھندسیة المجلم امیل محمد رحمن 14 نوع فاعالت الحیویة المزودة بزعنفة الخلط من مبقیم معامالت انتقال األوكسجین في ال وءالتنب rushton turbine غیر المیكروبیة(المقلدة األوساطفي ( ***اسیل عبد الجبار **م معلىظشذى كا *امیل محمد رحمن المیاح جامعة بغداد/ كلیة الھندسة الخوارزمي/ ائیة االحیائیةقسم الھندسة الكیمی***،**،* drameel@kecbu.uobaghdad.edu.iq: البرید االلكتروني* shatha_engr@yahoo.com: البرید االلكتروني** aseel_133@yahoo.com:االلكتروني البرید*** الخالصة rushtonلتر مزود بخالط یحتوي على زعنفة خلط من نوع ٥اجریت دراسة حول انتقال االكسجین على نطاق مختبري في مفاعل حیوي سعة turbine . ،تم استعمال نظام الھواء. سرعة زعنفة الخلط، الطاقة المسلطة ولزوجة السائل على انتقال االوكسجینتمت دراسة تاثیر سرعة الغاز الفراغیة / أظھرت النتائج المختبریة أن معمل انتقال . حجم/وزن ٣الى ٠.٥من cmcتراوح تركیز . لھذه الدراسة ةط سائلاوساك cmcمحلول / الماء والھواء تم ربط النتائج المختبریة لمعامالت انتقال . اغیة لغاز االوكسجین وسرعة زعنفة الخلط، ویقل بزیادة لزوجة السائلاالوكسجین یزداد بزیادة السرعة الفر ضمن ) الطاقة الكلیة المسلطة على النظام والسرعة الفراغیة لغاز االوكسجین( االوكسجین بعالقة ریاضیة التي تصف تأثیر العوامل التي تم التطرق الیھا ً مع النتائج المختبریة klaاعطت نتائج قیم . لتي حددت في البحثالمدیات ال تم الحصول على : المستحصلة من المودیالت الریاضیة، نتائج مقبولة مقارنتا :العالقات االتیة :الماء/ نظام الھواء ( ) 4.30 43.1 088.0 g l g l v v p ak       = air/cmc system (0.5w/v ) ( ) 522 3.2 06.0 g l g l v v p ak       = air/cmc system (1w/v ) ( ) 811 3.2 06.0 g l g l v v p ak       = air/cmc system (2w/v ) ( ) 1623 3.2 06.0 g l g l v v p ak       = air/cmc system (3w/v ) ( ) 1576 3.2 06.0 g l g l v v p ak       = mailto:drameel@kecbu.uobaghdad.edu.iq mailto:shatha_engr@yahoo.com mailto:aseel_133@yahoo.com مها هادي al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 6976 (2013) al-khriet agricultural waste adsorbent, for removal lead and cadmium ion from aqueous solutions maha h. al-hassani department of chemical engineering/ college of engineering/ university of baghdad (received 5 november 2012; accepted 30 april 2013) abstract the availability of lowcost adsorbent namely al-khriet ( a substance found in the legs of typha domingensis) as an agricultural waste material, for the removal of lead and cadmium from aqueous solution was investigated. in the batch tests experimental parameters were studied, including adsorbent dosage between (0.2-1) g, initial metal ions concentration between (50-200) ppm (single and binary) and contact time (1/2-6) h. the removal percentage of each ion onto al-khriet reached equilibrium in about 4 hours. the highest adsorption capacity was for lead (96%) while for cadmium it was (90%) with 50 ppm ions concentration, 1 g dosage of adsorbent and ph 5.5. adsorption capacity in the binary mixture were reduce at about 8% for lead and 12 % for cadmium, which was attributed to competitive adsorption. the adsorption parameters were analyzed using both the freundlich and langmuir. al-khriet was best fitted by the freundlich isotherm comparing with langmuir model, and the rate constant was found to be 1.305 and 0.621 ((mg/g)(l/mg)1/n) for lead and cadmium respectively , while the kinetic of adsorption obeyed a second order rate equation and the rate constants were found to be (0.0161) for lead and ( 0.0125) mg.g-1.min-1 for cadmium. keywords: agricultural waste adsorbent, biosorption, heavy metal ions, isotherm kinetic model. 1. introduction the rapid progress in industrial technology and war remnants in iraq causes an increase in the level of toxic ions discharged into the waste water and these metals are harmful to the human and aquatic lives. many countries pay attention to this global issue and they devote concentrated efforts to solve this environmental problem (abdel-ghani et al., 2009). lead is one of the very dangerous heavy metals, which causes many dysfunctions in all human beings. in children, excess amounts of this metal would probably lead to a decrease in their iq score, and an impairment of learning, hearing, physical growth, the circulating system, the reproductive system, nervous system especially the brain, kidney functions and some mental disease such as dementia, depression, madness, as well as problems in metabolism system.,e.g., deficiency of vitamin d, also increasing level of this toxic metal may lead to death (okoye et al., 2010, okoro and ejike, 2007). lead as (pb+2) has a huge efficiency to the thio (-sh) and (po4) containing enzymes and other dangerous molecules which in turn affecting the permeability of kidney, liver and brain cells by inhibiting the synthesis of heams unit, leading to retardation or break down of these organs function (ademoroti, 1996). cadmium is another of heavy metals with a high toxicity. accumulation of cadmium in the body results in, diarrhea, muscular cramps, nausea, erythritis, problem in the vision, chronic pulmonary disease (cpd), and cardio vascular disease (cvd). the world health organization (who) gave the recommended standards of drinking water which is 0.005mg cd/l and 0.001 mg pb/l (munther i. et al.,2010). while in iraq in the trocar of al-eshaki because of the effect of alsomood company for steel industry and power plant in the south of baghdad, the level of toxic metals (cd+2,pb+2) exceeded the allowed limit for example, the concentration of cadmium ion was 8 mg/l and the concentration of lead ion was 10 maha h. al-hassani al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 6976 (2013) 70 mg/l which was must higher than the permissible limits for drinking water. many techniques such as ion exchange, precipitation, adsorption, flocculation, advance oxidation and membrane process have been used for the removal of toxic metal ions (sheela et al., 2012, mohamad et al.,2012). the reason behind our using the absorption technique is that it is a very economical process especially when using a locally available adsorbent (saad al-jlil, 2010). the essential benefits of this absorption process for environmental pollution are: the low cost, simple design easy operation as well as no effect of toxic substance, when comparing to other biological treatment process (yahia, 2006, hameed et al., 2009). this research investigated the possibilities for using cheap wasted material, locally available in iraq namely al-khriet which is found as a powder in the legs of typha domingesis as potential adsorbent. the presence of this plant in industrial waste water indicates that it resists the pollutants. the effect of various parameters including the adsorbent dosage initial of metal ion concentration (single and binary) and contact time were studied onto al-khriet powder for removal lead and cadmium ion from aqueous solution. by reviewing other literature surveys, it is obvious that a few of them were performed on the contamination levels of different heavy metals in the waste water in iraq. 2. material and methods 2.1. material al-khriet was collected from marshes in the south of iraq. first it was washed with deionized water to remove the suspended particle and then dried in the air for two days before drying in an oven at 110°c for 24 hours, finally al-khriet powder was stored in discator. 2.2. experimental work different concentrations of cd+2,pb+2 aqueous solution were prepared from the stock of 500 mg/l solution prepared by dissolving agent grade pb(no3)2.2h2o and cd(no3)2 in dionized water, the properties of these compound were shown in table 1. adsorption was performed in a batch experiment. the equilibrium isotherms were determined by mixing 0.5gm of al-khriet with 25 ml of cd+2,pb+2 solutions in a conical flask at different concentration (50,100,150 and 200) mg/l. flasks were shaken in a shaker (type b,baun karlkob) for 4 h at room temperature. it was noticed that the adsorbed metals ions of adsorbent system reached to equilibrium after 4 h. this phenomenon was clearly seen in a series of experiments of different time intervals which showed that the adsorption process reached equilibrium after 4 h. solution and adsorbents were separated by filtering through a filter paper. the concentration of the solute in solution was determined by using atomic absorption spectrophotomeric (type perkin-elmer-5000, usa) . the adsorbed amount was calculated by the following equation: w ccv q e e )( 0− = …(1) where eq (mg/g) is the amount adsorbed at equilibrium, v (l) is the volume of solution, 0c , ec (mg/l) is the initial and equilibrium concentration, w (g) is the amount of adsorbent. the adsorption kinetic was analyzed by adding 0.5 g of al-khriet to 25 ml of 50 mg/l of cd+2, pb+2 solutions. the samples were shaken and examined at different time intervals. the effect of adsorbent dosage and initial concentration of the feed solution were also studied by using different amount of adsorbent (0.2-1) gm for initial concentration of (50-200) mg/l (single and binary). the ph value for cadmium and lead were 5.5 before and after mixing with adsorbent. 0.1m of naoh and hcl were used for ph adjustment to fix the ph value in all experiments. table 1, physical properties of adsorbate. 3. results and discussion the removal efficiency was calculated by the equation below removal efficiency 100*)( 0 0 c cc r f− = …(2) adsorbate lead nitrate cadmium nitrate molecular weight (g/mol) 367.2098 236.4208 water solubility (g/ 100ml h2o) at 20°c 52 136 maha h. al-hassani al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 6976 (2013) 71 where 0c and fc are the initial and final ions concentrations, respectively. 3.1. effect of contact time as shown in fig.1, the percent removal of lead ion and cadmium ion by adsorption onto al-khriet increases with contact time and attain equilibrium in about 4 h. removal efficiency equal to (94.6%) and (85.9%) for lead and cadmium ion respectively at ph 5.5 and of 50 ppm ions concentration and 0.5 gm of adsorbent in 4 h. the result indicates that the rate of sorption of both ions on al-khriet was fast because of a largest amount of cd+2,pb+2 attached to the sorbents within 1 h of adsorption. similar results were reported by mahvi et al.,(2007), ajmal et al.,(2003) and madhava et al., (2008). this behavior suggests that the initial stage, sorption takes place rapidly on the external surface of the al-khriet followed by a slower internal diffusion process, which may be the rate determine step. the reason behind our studying this part because the equilibrium time is one of the parameters for economical waste water treatment plant application. these observation agree well with the investigation by hameed et al., (2009). lead was found to adsorb more than cadmium, that is due to its different affinities of two ion for the reactive functional groups located on the surface of alkhriet powder. 0 20 40 60 80 100 0 50 100 150 200 250 300 350 time(min) r em ov al p er ce nt % lead cadmium fig. 1. effect of time on the removal efficiency using al-khriet as adsorbent, biomass dosage 0.5 g, ph 5.5, 250 rpm , cd+2 , pd+2 concentration 50 ppm. 3.2. the effect of al-khriet dose on ions adsorption the relation between al-khriet dose and % removal efficiency of cd+2 and pb+2 are shown in figs. 2 and 3. the experiments were carried out at ph 5.5 and fixed cd+2 and pb+2 initial concentrations for both single and binary of 50 ppm solution on al-khriet. as can be depicted from these figures, when al-khriet dose increased, the uptake of both ion decreased and the percent removal increased for both single and binary solution due to the great possibility of exchangeable sites or surface area. it is appearance that by increasing the dosage from (0.2-1) g, the percent removal increased from (92% to 96%) for lead and from (83% to 90%) for cadmium as shown in fig.2. figure 3. shows that the adsorption curve for two solute together. in the binary solution adsorption percent removal of pb+2 and cd+2 were 88%, 79% with 1 g dosage and 50 ppm ion concentration. this indicates that the adsorption capacities of the adsorbent observed in binary mixture batch experiments were lower (about 8% for pb and 12% for cd) than that observed in a single solute, which was attributed to competitive adsorption. competitive adsorption results from the available adsorption sites existing on the surface of the adsorbent when present in a multi-component metal ion aqueous solution. it was found that the removal efficiency of al-khriet for pb+2 is grater than cd+2. it can be clearly seen from table 1 that lead nitrate is less soluble than cadmium nitrate which attribute to their molecular weight, duo to the fact that the higher molecular weight, the lower solubility in a water is similar trend was reported by riaz qadeer (2002). this behavior might be also attributed to the molecular size. lead ion has the smaller molecule than cadmium ion, thus it might be visible for on particular pore hold more lead ions molecules than cadmium ions molecules. the decreasing trend in adsorbed phase concentration for cadmium ion is due to the less availability of sites on the al-khriet because of the competitive effect of lead ions. maha h. al-hassani al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 6976 (2013) 72 60 70 80 90 100 0 0.2 0.4 0.6 0.8 1 1.2 adsorbrnt dosage r em ov al p er ce nt % lead cadmium fig. 2. effect of adsorbent dosage on the percent removal for single of cd+2, pb+2 by al-khriet , contact time 4 h, initial concentration for both ion 50ppm. 60 70 80 90 100 0 0.2 0.4 0.6 0.8 1 1.2 adsorbrnt dosage r em ov al p er ce nt % lead cadmium fig. 3. effect of adsorbent dosage on percent removal for binary system of cd+2, pb+2, using initial concentration for each ion 50 ppm. 3.3. effect of initial cd+2, pb+2 ions concentration figure 4 showed the relation between the percent removal efficiency and the initial ions concentration of cd+2 and pb+2, as the initial ions concentration increase the percent removal decreases. that is because at higher concentration, number of heavy metals were relatively higher in comparison with the availability of adsorbent sites. these observation agree well with the investigation reported by sulaymon et al., (sulaymon et al.,2010) . 0 10 20 30 40 50 60 70 80 90 100 0 50 100 150 200 250 ppm r % lead cadmium fig. 4. removal of cd+2, pb+2 ion using different concentration of ions. 3.4. adsorption kinetic model the pseudo first order model (pfom) (augustin and emmanual,2011) is given by the following equation tkqqq ete 1ln)ln( −=− …(3) the pseudo second order model (psom) (augustin and emmanual,2011) is given by the following equation eet q t qkq t += 2 2 1 …(4) where eq is the amount of ions adsorbed at equilibrium (mg.g-1), tq is the amount ions adsorbed at time t in ( mg.g-1 ), 1k (min-1) and 2k (g/(mg.min)) are the rate constants of pfom and psom respectively. the pfom and psom plots shown in fig. 5 and 6. 1k and 2k for cd+2, pb+2 as well as correlation coefficient obtained are presented in table 2. it can be found out that the obtained correlation coefficient for psom were greater than for pfom. these suggest that the adsorption system is the second order model based on assumption that the both sorbate (pb,cd) and al-khriet are involved in a rate determining step, which may be a chemical sorption rather than diffusion. (ho and mckay, 1998). maha h. al-hassani al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 6976 (2013) 73 -3.5 -3 -2.5 -2 -1.5 -1 -0.5 0 0 50 100 150 200 250 time ln (q eq t ) lead cadmium fig. 5. pfom plots for cd+2, pb+2. 0 20 40 60 80 100 120 140 0 50 100 150 200 250 300 tim e(min) t/q t lead cadmium fig. 6. psom plots for cd+2, pb+2. table 2, the rate constant and correlation coefficient for pseudo first and second order for both ions. kinetic model parameters pb+2 cd+2 pfom k1(min-1) 0.0161 0.0099 eq (mg/g) 1.50 1.22 r1 2 0.9718 0.9613 psom k2 (mg.g-1. min-1) 0.0161 0.0125 eq (mg/g) 2.582 2.353 r1 2 0.9991 0.9866 3.5. equilibrium isotherms the equilibrium isotherm display a nonlinear dependence on the equilibrium concentration. the obtained adsorption data were analyzed using freundlich and langmuir (ajay et al., 2010) isotherms according to the following equation: nee kcq 1 = …(9) freundlich e em e bc bcq q + = 1 …(10) langmuir equations 9 and 10 can be written in linear form as given below respectively efe c n kq ln1lnln += …(11) bqq c q c mm e e e 1 += …(12) where eq and ec are the equilibrium concentration of lead and cadmium in adsorbed and liquid phase in mg/g and mg/l , respectively , fk and n are the freundlich constants which can be calculated from the slope and intercepted of the linear plot with eqln vs. ecln . mq and b are langmuir constants which can be calculated from the intercept and slope of the linear plot ee qc / vs. ec . the freundlich and langmuir isotherms are shown graphically in figs. 7 and 8. the fitted constant for two models are tabulated in table (3). table (3) indicate the freundlich model provides the best fit as judged by its correlation coefficient for pb+2and cd+2. the n value of freundlich model between 1 and 10, indicates good adsorption efficiency (treybal,1980). this demonstrate that the developed adsorbent has good adsorption efficiency for pb+2,cd+2 removal. 0 0.5 1 1.5 2 2.5 0 1 2 3 4 5 ln(ce) ln (q e) lead cadmium fig. 7. adsorption isotherm of pb,cd at ph (5.5) by using freundlich. maha h. al-hassani al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 6976 (2013) 74 0 1 2 3 4 5 6 7 0 10 20 30 40 50 60 ce c e/q e lead cadmium fig. 8. adsorption isotherm of pb,cd at ph (5.5) by using langmuir. table 3, parameter of isotherms for cd ,pb and correlation coefficient for freundlich and langmuir isotherm r2. kinetic model parameters pb+2 cd+2 langmuir mq (mg/g) 13.9 12.85 b l/mg 0.070 0.028 r2 0.9867 0.9734 freundlich n f mg l g mgk 1 )( 1.305 0.621 n 1.636 1.529 r2 0.9983 0.9928 4. conclusion the investigation show that al-khriet a local natural agent which is are abundant and low cost, therefore can be used as a bioadsorbent for removal pb+2, cd+2 ions from aqueous solutions. it was noted that removal process increased with contact time and attains saturation in about 4 h. the rapid kinetic of adsorption process has significant practical importance ensuring efficiency and economy. also the adsorption of pb+2, cd+2 on al-khriet was dependent on initial concentration and dosage of adsorbent. adsorption capacity for cadmium was less than that for lead , the highest adsorption capacity was for lead (96%) and for cadmium (90%) with 50 ppm ions concentration, 1 gram dosage of adsorbent and ph 5.5, while the mixed heavy metal were reduced at about 8% for pb and 12% for cadmium. in this study of kinetic of adsorption, the psom provides better correlation of sorption data than the pfom , while the adorption equilibrium was better described by freunlich model than langmuir model. hence the material al-khriet under consideration would be useful economical treatment of waste water containing lead and cadmium metal. 5. references [1] abdul-ghani n.t. , a.k. hegazy, g.a.el chaghaby,2009. typha domingensis leaf powder for decontamination of aluminum, iron,zinc and lead, biosorption kinetics and equilibrium modeling, int. j.environ. sci. tech., 6(2),243-248. [2] ademoroti,c.m.a., 1996. environment chemistry and toxicology ,pollution by heavy metal. foludex press, 171-172. [3] ajay kumar meena, chitra rajagopal, kiran and gk mishra. 2010. removal of heavy metal ion from aqueous solution using chemically (na2s) treated granular activated carbon as an adsorbent, journal of scientific and industrial research vol 69, pp 449-453. [4] ajmal,m.,roa,r.a., anwar,s., ahmad,j., alunad,r. 2003.adsorption studies on rice husk., removal and recovery of cd(ii) ion from waste water, bioresour.technol., 86(21), 147-149. [5] augustine e. ofomaja, emanuel i.,2011. adsorption kinetics of 4-nitrophenol onto a cellulosic material, mansonia wood saw dust and multi stage batch adsorption process optimization, carbohydrate polymers, 83,1192-1206. [6] hameed b.h., j.m. salman,a.l. ahmad. 2009. adsorption isotherm and kinetic modeling of 2,4-d pesticide on activated carbon derived from date stone, journal of hazardous materials, 163, 121-126 . [7] ho,y.s. mckay,g.a., 1998. comparision of chemisorption kinetics model applied to pollutant removal or various sorbents. transactions of the institution of chemical engineering, 76b,332-340. [8] madhave m. rao,g.p.chandra rao, k. seshaiah, n.v. ghoudary, m.c.wang. 2008. activated carbon from ceiba pentandra hulls, an agriculture waste as an adsorbent in the maha h. al-hassani al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 6976 (2013) 75 removal of lead and zinc from aqueous solution", waste management, 28, 849-858. [9] mahvi,a.h., nour,j,qmani, g.a., gholami,f., 2007. application of platanus orientalis leaves in removal of cadmium from aqueous solution. world appl. sci. j., 2(3), 40-44. [10] mohamad m. ayad, ahmed abu el-nasr, jaroslav stejskal, 2012. kinetics and isotherm studies of methylene blue adsorption onto polyaniline nanotubes base / silica composite, j. ind. eng. chem. http://dx.doi.org/10.1016/j.jiec. [11] munther i.kandah, fahmi a. abu al-rub, lucy bawarish, mira bawarish, hiba altamimi, reem khalil, and raja'a saad, 2010. adsorption of cadmium onto activated and non-activated date pits , world academy of science, engineering and technology, 62. [12] okoro,i.a.,ejike,e.n.,2007.sorption model of pb(ii) removal from aqueous solution using common edible fruit waste, eur.j.sci.res., 17(2), 270-276. [13] okoye a.i., p.m.ejikeme, o.d.onukwuli, 2010. lead removal from wastewater using fluted pumpkin seed shell activated carbon adsorption modeling and kinetics, int.j.environ.sci.tech., 7(4), 793-800. [14] riaz qadeer,2002. a study of the adsorption of phenol by activated carbon from aqueous solution, yurk.j.chem.,26,357-361. [15] saad, a. al-jlil, 2010, removal of heavy metals from industrial wastewater by adsorption using local bentonite clay and roasted date pits in saudi arabia. trends in applied science reseach 5(2),138-145. [16] sheela t.,y.arthoba nagaka ,r. viswanatha, s. basavanna, t.g.venkatesha, 2012 .kinetics and thermodynamics studies on the adsorption of zn(ii), cd(ii) and (hgii)from aqueous solution using zinc oxide nanoparticles, powder technology, 217,163-170. [17] sulaymon, abbas h., shahlaa e. ebrahim, sama m. abdullah,tariq j.al-musawi, 2010. removal of lead,cadmium and mercury ion using biosorption , desalination and water treatment, 24,233-352. [18] yahia a.alhamed, 2006 , activated carbon from dates stone by zncl2 activation, ikav: eng. sci. vol.17 no.2, 72-100. )2013( 6976، صفحة 2، العدد9مجلة الخوارزمي الھندسیة المجلد مھا ھادي مصطفى 76 المائیھ المحالیل من والكادمیوم الرصاص ایونات الزالھ مازه كماده الخریط استخدام مھا ھادي مصطفى الحسني جامعة بغداد /كلیة الھندسة / قسم الھندسة الكیمیاویة الخالصة ك الخریط المائی ھ المحالی ل من والكادیمیوم كالرصاص الثقیلھ المركبات الزالة كلفھ وباقل محلیا المتوفره الزراعیھ النفایات استخدام الى البحث یھدف معا وممزجھ منفرده بصوره والكادیمیوم الرصاص أیونات تركیز ،المازه الماده تركیز تأثیر دراسة تم .مازه كماده البردي نبات سیقان في موجوده ماده وھو درجھ، التشغیلیھ الظروف عن% ٩٠ وللكادیمیوم% ٩٦ للرصاص ازالھ نسبھ عاى الحصول تم. الممتزه والكمیھ لألزالھ الموئیھ النسبھ عن األمتزاز وزمن % ٨ بح والي األمت زاز نسبة قلت األیونات مزج وعند ساعھ ٤ األمتزاز وزمن لتر لكل ملغم ٥٠ األیونات وتركیز غم ١ المازه الماده وكمیة ٥,٥ حامضیھ استخدام وكان, ناجح بشكل وفریندلج النكمایر معادلة استخدام تم. للخریط الفعالھ المراكز على والتنافس التزاحم ظاھرة بسب للكادیمیوم% ١٢و للرصاص من لكل غم \ملغم ٠,٦٢١ و ١,٣٠٥ النكمایر ثابت معدل كان حیث فریندلج معادلھ من افضل بشكل األیونات من كل امتزاز نتائج لتمثیل النكمایر معادلھ ٠,٠٦١ األمتص اص ثاب ت مع دل ك ان حی ث الثانی ھ الدرج ھ م ن بمعادل ھ تمثل ت األمتص اص عملی ة حركی ة بینم ا الت والي عل ى والك ادیمیوم الرص اص .التوالي على والكادیمیوم الرصاص من لكل دقیقھ غم\ملغم٠,٠١٢٥و ali r. mohammed jawad al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 8, no. 1, pp 37 -47 (2012) effect of solid properties on axial liquid dispersion in bubble column ali raad mohammed jawad department of chemical engineering /university of technology email: aliolimpic@yahoo.com (received 30 june 2011; accepted 13 december 2011) abstract experiments were conducted to study axial liquid dispersion coefficient in slurry bubble column of 0.15 m inside diameter and 1.6 m height using perforated plate gas distributor of 54 holes of a size equal to 1 mm diameter and with a 0.24 free area of holes to the cross sectional area of the column. the three phase system consists of air, water and pvc used as the solid phase. the effect of solid loading (0, 30 and 60 kg/m3) and solid diameter (0.7, 1.5 and 3 mm) on the axial liquid dispersion coefficient at different axial location (25, 50 and 75 cm) and superficial gas velocity covered homogeneous-heterogeneous flow regime (1-10 cm/s) were studied in the present work. the results show that the axial liquid dispersion coefficient increases with increasing superficial gas velocity, axial distance, solid concentration and an inverse relationship with particles diameter. keywords: axial liquid dispersion coefficient; axial dispersion; mixing; liquid circulation; backmixing; slurry bubble column; bubble column. 1. introduction slurry bubble column are multiphase contactors widely used as absorbers, strippers and reactors in chemical, biochemical and petro chemical industrial processes, because of their advantages as simple construction and excellent heat and mass transfer, as mixing is induced only by gas aeration [1,2]. holdup and axial dispersion of liquid are two important parameters affecting the performance of the gas – liquid contacting devices. wrong estimations of liquid holdup and axial dispersion lead to an unexpected low performance [1]. flow distribution in different axial locations is an important aspect of study in gas-liquid-solid three phase fluidized beds [3]. the main drawback is a severe degree back mixing in the liquid phase, which is due to the low liquid flow rate. back mixing is known to increase drastically when local liquid circulation develops [4]. the dispersion coefficient is expressed in dimensionless form as peclet number (pe); its value denoting the degree of back mixing in the column. if pe=0 back mixing is complete and if pe=∞ plug flow prevails [1]. axial and radial mixing of the liquid phase in bubble columns is characterized by using dispersion coefficients that are analogous to the diffusion coefficient of fick's law diffusion [1]. the estimation of the axial dispersion coefficient of the liquid phase is important for the design and scale up of bubble column reactors [2]. dispersion coefficients are generally calculated using the measured concentration – time response to input of a nonreactive, nonabsorptive inter tracer in the reactor. the methodology is well established for calculating the axial dispersion coefficient only, as the one dimensional dispersion model that is typically used for the fitting contains axial dispersion coefficient as the only fitting parameter [5]. it is usually assumed that the dispersion coefficient does not depend on the column height [6]. unlike diffusion, dispersion arises from convective motion of fluid caused by the following main factors : relative movement of the gas and liquid phase; bubble coalescence and break up; the mailto:aliolimpic@yahoo.com ali raad mohammed al-khwarizmi engineering journal, vol. 8, no. 1, pp 37 47 (2012) 38 carry forward of liquid in wakes behind the rising gas bubbles and the consequent return flow generated for maintaining mass balance; and turbulence generated by any superimposed flow of liquid [1,2]. as far as is known, in all previous dispersion studies in semi batch packed bubble columns performed, the tracer has been added directly to the top of the bed. in co – or counter – current flow reactors, the tracer is generally injected to the liquid inlet stream whereas the response is measured at the outlet [7]. the mixing process involves a shuffling or redistribution of material either by slippage or eddies; this repeated a considerable number of times during the circulation in the reactor [5]. ichikawa and chen found a significant effect of superficial liquid velocity on axial liquid dispersion coefficient [8]. the effect of solid concentration and particle size on gas holdup has been investigated by a number of researchers. several researches concluded that an increase in solids concentration generally reduces the gas holdup [9]. the influence of particle size on hydrodynamics of bubble column has been found to depend on a number of factors including flow regime, gas velocity, liquid properties and slurry concentration [10]. shawaqfeh [11] reported that the liquid superficial velocity had negligible effect on gas holdup, but had significant effect on the axial dispersion coefficient. the axial liquid dispersion coefficient was found to depend on both gas and liquid velocities. shah et al., [1] stated that the increase in gas velocity generally increases the liquid dispersion coefficient. therning and rasmuson [12] using packed bubble column, reported that in both homogeneous and heterogeneous flow regime the one dimensional axial liquid dispersion coefficient increases with increasing gas velocity. krishna et al., [13] measured the axial liquid dispersion coefficient at three metrophm immersing-type conductivity cells which were placed near the wall. rubia et al., [5] reported that the value of the radial dispersion coefficient was typically about 1% axial liquid dispersion coefficient value under any given condition. the larger bubbles in tap water underwent more frequent breakup and coalescence and this increased the axial liquid dispersion coefficient. the aim of the present work is to study the effect of solid concentration and particle size at different axial location and superficial gas velocity (covered homogeneous-heterogeneous flow regime) on the axial liquid dispersion coefficient. 2. experimental experiments were carried out in a qvf cylindrical bubble column of (15 cm inside diameter and 1.6 m height) with static liquid height (100 cm). the system is operated in a semi-batch mode with stagnant liquid and continues gas flow. a schematic diagram is shown in fig. (1). in all experiments, the liquid phase was tap water and the gas phase was air. the air flow rate was measured with a pre-calibrated rotameter. a compressed air was dispersed from the bottom of the column through perforated plate consisted of 54 hole, 1 mm diameter and free surface area to cross sectional diameter of 0.24. pvc particles (1025 kg/m 3 density) were used as the solid phase. different particles size were used (0.7, 1.5 and 3 mm) and different loading solid particles (0, 30 and 60 kg/m 3 ) were used in the experiments. for the tracer experiments, residence time distribution (rtd) of the liquid phase was measured using different amounts of saturated solution of nacl as a tracer. different volumes of tracer were used to obtain the optimal amount of tracer that corresponds to optimal signal within the operating range of conductivity cell. this optimal amount of a saturated solution of nacl was found equal to 5 wt % .the probes were placed on three points (25, 50 and 75 cm) from the distributer axially. the signals from the electrodes were transmitted to conductance meter (philips type). the meters were connected via an interface to a pc computer. tracer was injected as a pulse input; local changes in tracer concentration were displayed and saved continuously on pc. ali raad mohammed al-khwarizmi engineering journal, vol. 8, no. 1, pp 37 47 (2012) 39 fig.1. schematic diagram of the experimental apparatus. 3. theoretical analysis in order to characterize mixing in bubble column, a two dimensional dispersion model has been used. the dimensionless tracer concentration can be written as [14, 5]: …(1) where: …(2) …(3) …(4) accordingly when ct in eq. (1) is radially invariant (i.e. dr=∞), υn, βand x become zero and j0t(υnβ)=j0(υnx) =1. in this case eq. (1) reduces to: …(5) the average axial liquid dispersion coefficient (dax.l av) was calculated: …(6) ali raad mohammed al-khwarizmi engineering journal, vol. 8, no. 1, pp 37 47 (2012) 40 4. results and discussion 4.1. liquid phase dispersion in bubble column the conductivity data used for the calculation of dispersion coefficients are smoothed in order to remove the noise that already present due to occasional gas bubbles being in contact with the conductivity probes. a typical set of the pulseresponse data and the best fit model curve generated using eq. (1) is shown in fig. (2). the value of the radial dispersion coefficient influenced the height of the model generated peak, whereas the value of the axial dispersion coefficient influenced the width of the peak. the solution of eq. (1) was found by using matlab r 2010b program. 4.2. radial liquid dispersion coefficient (dr,l ) this work takes into account only the axial (neglecting radial) liquid dispersion. fig. (3-9) showed that its value does not exceed 1%. this is in agreement with the results obtained by rubia et al., [5]. the few measurements of radial dispersion coefficients cited by deckwer [2], suggest that the radial dispersion coefficient is always less than onetenth of the value of the axial coefficient. moreover, joshi and sharma [15] showed that the radial component of the velocity, i.e. the component that is relevant to radial mixing, is only about 36% of the axial component. this explains, that the relatively poor radial mixing in bubble columns compared to the axial mixing. 4.3. axial liquid dispersion coefficient (dax,l) the method of calculation of (dax,l) carried out using equations (1) and (5) [i.e., using mathematical models with and without radial dispersion]. 4.3.1. effect of superficial gas velocity (ug) and axial distance of probe's location (z) on axial liquid dispersion coefficient (dax,l) fig. (3-9) show the effect of superficial gas velocity (ug) on the axial dispersion coefficient for different axial distance (z) from the distributor. it can be seen that, the axial dispersion coefficient increases with increase superficial gas velocity (ug). this can be attributed to the decrease in mixing time which results from the increases of the average liquid circulation velocity (vc) which increases with the increase of (ug). this result is in agreement with therning and rasmuson [12] and shah et al., [1]. the axial dispersion coefficient increases slightly with increasing superficial gas velocity in the homogeneous regime (0-4 cm/sec) and then the increasing rate becomes faster in the heterogeneous regime (5-10 cm/sec). moreover the axial liquid dispersion coefficient (dax,l) increases with increase of the axial distance (z). this increases in (dax,l) due to a decrease in bubble rise velocity results from a decrease in bubble diameter and consequently increasing the liquid circulation velocity (vc), then increase (dax,l). these results are in agreement with krishna et al., [13]. r/r=0, ug=5 cm/s 0 1 2 3 4 0 10 20 30 40 time (s) c t / c 0 experimental model fitz1 z2 z3 c t fig. 2. typical conductivity responses of different probes. ali raad mohammed al-khwarizmi engineering journal, vol. 8, no. 1, pp 37 47 (2012) 41 fig. 3. effect of superficial gas velocity on axial liquid dispersion coefficient at different z and cs=0. fig. 4. effect of superficial gas velocity on axial liquid dispersion coefficient at different z, cs=30 and dp=3mm. fig. 5. effect of superficial gas velocity on axial liquid dispersion coefficient at different z, cs=60 and dp= 3mm. d ax .l ( cm 2 /s ) ug (cm/s) d ax .l (c m 2 /s ) ug (cm/s) d ax .l (c m 2 /s ) ug (cm/s) ali raad mohammed al-khwarizmi engineering journal, vol. 8, no. 1, pp 37 47 (2012) 42 fig. 6. effect of superficial gas velocity on axial liquid dispersion coefficient at different z, cs=30 and dp= 1.5mm. fig. 7. effect of superficial gas velocity no axial liquid dispersion coefficient at different z, cs=60 and dp= 1.5mm. fig. 8. effect of superficial gas velocity no axial liquid dispersion coefficient at different z, cs=30 and dp= 0.7mm. d ax .l (c m 2 /s ) ug (cm/s) d ax .l ( cm 2 /s ) ug (cm/s) d ax .l ( cm 2 /s ) ug (cm/s) ali raad mohammed al-khwarizmi engineering journal, vol. 8, no. 1, pp 37 47 (2012) 43 fig. 9. effect of superficial gas velocity no axial liquid dispersion coefficient at different z, cs=60 and dp= 0.7mm 4.3.2. effect of solid concentration (cs) on axial liquid dispersion coefficient (dax,l) fig. (10-12) show the effect of solid concentration on average axial dispersion coefficient. it can be seen that, the axial dispersion coefficient increases with the increase of solid concentration. this may be due to the fact that when the solid concentration increases lead to higher gas bubble concentration produced. since the liquid envelopes the gas bubbles, therefore it will be entrained and dragged upwards and also part of gas – liquid dispersion will flow downwards again and consequently causing an increase in the liquid phase dispersion coefficient. these results are in agreement with deckwer [2]. fig.10. effect of superficial gas velocity and solid concentration on average axial liquid dispersion coefficient at dp= 3mm. d ax .l ( cm 2 /s ) ug (cm/s) d ax .l a v ( cm 2 /s ) ug (cm/s) ali raad mohammed al-khwarizmi engineering journal, vol. 8, no. 1, pp 37 47 (2012) 44 fig. 11. effect of superficial gas velocity and solid concentration on average axial liquid dispersion coefficient at dp= 1.5mm. fig. 12. effect of superficial gas velocity and solid concentration on average axial liquid dispersion coefficient at dp= 0.7mm. 4.3.3. effect of particle diameter (dp) on axial liquid dispersion coefficient (dax,l) fig. (13 and 14) show the effect of superficial gas velocity for various particle diameters. from these figures it can be noticed an inverse relationship between particles diameter and axial liquid dispersion coefficient. this can be attributed to the fact that the bubble rise velocity decreases lead to the rate of bubble coalescence increases as the particles diameter decreases. the larger bubbles which results from coalescence lead to an increase the axial liquid dispersion coefficient. this result is in agreement with rubia et al., [5]. d ax .l a v ( cm 2 /s ) ug (cm/s) d ax .l a v ( cm 2 /s ) ug (cm/s) ali raad mohammed al-khwarizmi engineering journal, vol. 8, no. 1, pp 37 47 (2012) 45 fig. 13. effect of superficial gas velocity and solid concentration on average axial liquid dispersion coefficient at cs= 30kg/m3. fig. 14. effect of superficial gas velocity and solid diameter on average axial liquid dispersion coefficient at cs= 60kg/m3 5. conclusions the following major conclusions can be drawn from the present work. 1. in homogeneous regime (0-4), axial liquid dispersion coefficient increases slightly with increasing superficial gas velocity while it increases rapidly in heterogeneous regime. 2. increases the axial distance of the probe's location led to increase the axial liquid dispersion coefficient. 3. increasing solid concentration the gas – liquid flow exhibit higher gas bubble concentration led to increase the axial liquid dispersion coefficient. 4. axial liquid dispersion coefficient decreases with increasing particle diameter. nomenclature c tracer concentration, kmol m −3 ct dimensionless tracer concentration defined by eq. (4) c0 initial concentration of the tracer, kmol m −3 c∞ final or equilibrium concentration of the tracer, kmol m −3 dax.l axial liquid dispersion coefficient., m 2 s -1 dr radial liquid dispersion coefficient, m 2 s -1 j0 zero-order bessel function j1 first-order bessel function l height of dispersion, m t time or instantaneous time, s d ax .l a v ( cm 2 /s ) ug (cm/s) d ax .l a v ( cm 2 /s ) ug (cm/s) ali raad mohammed al-khwarizmi engineering journal, vol. 8, no. 1, pp 37 47 (2012) 46 ug superficial gas velocity, ms −1 y dimensionless axial position z axial distance, m vc liquid circulation velocity cs solid concentration, kg/m 3 dp particle diameter n flow index greek symbols ʋn the nth root of the first-order bessel function π the number pi ɵ dimensionless time β parameter in eq. (1) m integer. 6. reference [1] shah, y.t., godbole, s.p., kelkar, b.g., deckwer, w.d., "design parameters estimation for bubble column reactors", aichej, 28(3); 353-379, (1982). 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(cited in:rubia et al., [5]). http://onlinelibrary.wiley.com/athens ((2012 37 47 ، صفحة1، العذد 8مجلة الخوارزمي الهنذسية المجلذعلي رعذ محمذ 47 تأثير خواص الصلب على التشتت الطولي للسوائل في ابراج التفقيع علي رعذ محمذ جواد الداهؼح الركٌىلىخٍح /قسن الهٌذسح الكٍوٍاوٌح aliolimpic@yahoo.com :الثرٌذ االلكرروًً الخالصة م تأسرخذام صفٍحح هثقثح 1.6م وارذفاع 0.15رو قطر داخلً (للسىائل الؼالقح)اخرٌد الردارب الؼولٍح لذراسح هؼاهل الرشرد الطىلً فً اتراج الرفقٍغ – الواء – تأسرخذام ًظام ثالثً هركىى هي الهىاء . ًسثح هساحح حرج للفرحاخ الى الوساحح الوقطؼٍح0.24هلن هغ 1 فرحح تقطر 54لرىزٌغ الهىاء ذحىي ػلى لذراسح ذأثٍرها ػلى ( هلن3 , 1.5 , 0.7)واقطار للصلة (3م/ كغن 60 ,30 , 0)أسرخذهد ذراكٍس هخرلفح هي الوادج الصلثح . (تىلً فٌٍٍل كلىراٌذ)الصلة اظهرخ الٌرائح . لرغطً الوٌطقح الورداًسح والغٍر هرداًسح (ثا/ سن10 – 1)وسرػح غاز ( سن75 , 50 , 25)هؼاهل الرشرد الطىلً واتؼاد طىلٍح هخرلفح .زٌادج هؼاهل الرشرد الطىلً للسائل هغ ازدٌاد سرػح الغاز والثؼذ الطىلً وذركٍس الصلة وًقصاى الوؼاهل هغ قطر الصلة mailto:aliolimpic@yahoo.com������ mailto:aliolimpic@yahoo.com������ <4d6963726f736f667420576f7264202d20dac8cf20c7e1d3cac7d120e6d3e5c7cf> al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 5464 (2013) the power enhancement of a mini-gas turbine by adding ethanol to the compressor inlet air abdul satar j. al-saraf* suhad a. r. al-jumaily** *,** department of machines and equipment / university of technology *e-mail: dr_asjsaraf@uotechnology.edu.iq **e-mail: s_jumaily@yahoo.com (received 10 october 2013; accepted 17 december 2013) abstract an experimental study is conducted on the utilization of the inlet ethanol injection technique in order to evaluate its impact on the performance of a two-shaft t200d mini-gas turbine engine. the maximum degradation recorded in power output was 32.8% at the climate temperature of 45 o c. nevertheless, at that temperature, adding ethanol with eth/lpg ratio of 20% by volume brought an enhancement in power output of 19.2% compared to normal lpg run. sfc of the dual-fuel engine ranked a level of 22% higher than that with pure lpg consumption. the overall efficiency suffered a maximum reduction of 14.4% with eth/lpg fuel ratio of 20%, but when the loading was raised beyond 70% of the engine full load; the efficiency of dual-fuel engine excelled the normal lpg engine by 3.1% at the corresponding eth/lpg ratio maintaining a power turbine speed of 12000 rpm. keywords: alcohol gas turbine, inlet cooling, alternative fuels, bio-fuels. 1. introduction the vast urban constructions accompanied by the development in commercial and industrial sectors led to a continuous growth in power demand during the last two decades in iraq. this situation requires urgent remedies to come out of the electricity and energy demand crisis. the 1973 oil crisis in the middle east caused a global search for alternative fuels that could replace petroleum-based fuels. utilization of biofuels with fossil fuels is a more economic option to provide renewable power. and, much like the automotive industry, the power industry will need to institute design changes to accommodate these fuels [1]. the gas turbine power plants have found increasing service in the last forty years due to the great amount of energy they produce for their size and weight. gas turbine compactness, low weight, flexible load accommodation, start-up easiness, and multiple fuel applications make it a natural power plant for off-shore platforms [2]. all of the current liquid biofuels used or being considered exhibit a lower heating value less than standard petroleum-based fuel ; thereby requiring a step increase in fuel flow to deliver the same power output. ethanol has already been tested in gas turbines and found to be an attractive renewable fuel option. its lower lubricity and low heating value, though, require changes to most standard gas turbine fuel and combustion systems [3]. ethanol has been known as a fuel for many decades since henry ford expected that ethanol, made from renewable biological materials, would be a major automobile fuel. however, it is not widely used because of its high price. in brazil, ethanol has been used as automotive fuel since 1925, due to its large territorial areas utilised for sugar cane planting. this motivates the automotive industry to start the development of engines and components adequate for this source of energy [4]. a land based gas turbine for power generation has the characteristics that the output falls on hot abdul satar j. al-saraf al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 5464 (2013) 55 summer days when the electricity demand peaks. this is because the high temperature causes air density to be less, reducing the mass flow of compressor intake air [5]. there are certain methods to reduce gas turbine inlet temperature, e.g. water evaporation, adsorption and mechanical cooling. this work focuses on the injection of liquid ethanol directly into the inlet air making use of its high latent heat of vaporization to be absorbed from the air itself causing its temperature to decrease. the reduction in inlet air temperature will in turn increase its density, as well as, its mass flow rate and hence, boost the power output. ethanol itself could be considered as an organic fuel that contributes to the heat addition to the engine. therefore, it may replace the petroleum fuel in purpose of improving the environment impact. ethanol injection into engine inlet air has the advantage of avoiding the harmful effects of ethanol on seals and gaskets of conventional fuel system if straight blended with the petroleum fuel. 2. literature survey one of the first studies on using alcohol in gas turbine engines was conducted by national advisory committee for aeronautics naca [6]. the investigation was carried out on a 4000 lbf thrust centrifugal flow type turbojet engine at maximum rotor speed of 11500 rpm by injecting water-ethanol mixture at compressor inlet. the maximum thrust augmentation of 26% was obtained by the injection of 31% alcohol by weight. the fuel flow and the tail-pipe gas temperature was the same as for no injection run. a blend of ethanol/jet a fuel in varying concentration ranging from 25 to 100% by volume was tested in a small-scale 30 kw gas turbine. the performance characteristics including the thrust, thrust specific fuel consumption were compared with that of jet a over a range of throttle settings. the results indicate that ethanoljet a blend is a viable alternative fuel for gas turbine engines [2]. it is a common practice to use excess air to control the combustion temperature. but, this excess air could be reduced if methanol vapour reformed by the turbine wasted heat is injected into the combustion gas [7]. this scheme would increase the net power output of the plant. when the time comes that allows us to use turbine inlet temperatures of 1,400 o c, the proposed cycle could achieve approximately 60% overall thermal efficiency. the air, as auxiliary medium is replaced with ethanol-water compound steam that produced with waste heat of a capstone c33 gas turbine. ethanol mass flow was increased up to 10% presenting the expected cooling on the inlet temperature [8]. but, when more ethanol is injected it cause a reduction in efficiency due to the unburnt ethanol that leaves with the exhaust gases. the steam of ethanol-water compound will not absorb significant amount of heat inside the combustor and lowering the flame temperature as the mixture of air and evaporated ethanol does. the results of performance testing of a 30 kw gas turbine engine supplied with biodiesel from palm oil, soy and ethanol showed that the latter have a 65% higher sfc than diesel fuel. ethanol showed the lowest efficiency among the fuels tested as a decrease of about 10% with respect to diesel was recorded [9]. general electric (ge) energy’s aeroderivative class of gas turbines has tested ethanol among many other biofuels to evaluate its sustainability as fossil fuels replacement, and the extent of environmental impact resulted from that conversion [3]. tests indicated a need for 30% increase in fuel flow concerning the combustion chamber and injectors redesign for burning the much lighter fuel. ge co. has been contracted by petrobras to convert one of the two units at a power plant near rio de janiero to burn ethanol [10]. a 43.5 mw, lm6000 gas-fired plant is believed to be the first power plant in the world powered by ethanol. the turbine burns 18000 litres per hour if operated continuously at base load capacity. the results were very satisfactory and very equivalent to that of any other liquid fuel. nevertheless, the cost of compatible dual-fuel turbine is between 5 to 10% more than a gas-only turbine considering the additional cost to install liquid fuel system to the gas turbine. 3. thermodynamic background it is known from carnot cycle that the maximum efficiency of a heat engine is determined by the average temperature of heat addition and heat rejection. in this case, we focus on reducing the inlet temperature of a gas turbine, which represents the lower cycle temperature. hence the cycle efficiency will increase because the average temperature of heat rejection has decreased. referring to figure (1), due to the abdul satar j. al-saraf al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 5464 (2013) 56 divergence of constant pressure lines on the (t-s) diagram, the final delivery air temperature will reduce as the compression commences from lower intake air temperature like ta instead of t1. consequently, the required compression work is reduced as the delivery temperature reduced. considering the overall pressure ratio yields [11]; fig. 1. effect of inlet temperature on the compression work.           −        = − 1 1 01 0201 γ γ η p pt cw c pc ...(1) this obviously shows the great effect of the inlet air temperature on the reduction of the compression work required. hence, the intended ethanol injection in the present work should decrease the compression power, as well as, increase the power output contributable to the increase in air mass flow resulting from the density improvement due to the inlet cooling. 4. cycle analysis the gas turbine performance is to be analysed by evaluating the cycle parameters which affected by the addition of ethanol to the inlet air. these parameters are to be used in demonstrating engine performance with the dual fuel as will be shown later in the results section. the air flow rate measured is calculated by the equation [12]; 1 010270 ρhma ∆= .& ...(2) then, this rate should be corrected as; 15288 0131 . . , a a aca t p mm       = && ...(3) the ethanol fuel flow is calculated by the rate equation;       = θ ρ eth etheth v m& ...(4) then this rate is also corrected as; eth ethceth t mm 15288. , && = ...(5) also, the main lpg mass fuel flow rate as measured directly, needs to be corrected as [12]; lpg p lpgclpg t f mm 15288 5811 . .,       = && ...(6) where, fp is a pressure based correction factor. hence, the total amount of dual fuel consumed is given by; cethclpgf mmm ,, &&& += ...(7) at this stage, it is now possible to determine the heat liberated by the burning of the dual fuel as; ethcethlpgclpgf hmhmq ,, &&& += ...(8) in order to estimate the performance criteria of the cycle, it first needs to determine the power produced by the engine which is an electric power calculated by; φ×= iw e & ...(9) therefore, the specific fuel consumption of the cycle is given by; e f w m sfc & & = ...(10) and the overall efficiency is determined as; f e ov q w & & =η ...(11) abdul satar j. al-saraf al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 5464 (2013) 57 5. experimental set-up 5.1. the test rig in purpose of carrying out the cooling needed to reduce the temperature of the gas turbine inlet air, a test rig has been constructed specially to introduce ethanol in the way of the incoming air such that increasing its mass flow by increasing its density. 1 starting blower 7 lpg fuel flow meter 13 ethanol atomiser 2 gas generator compressor 8 combustion chamber 14 air pre-heater 3 gas generator turbine 9 orifice air flow meter 15 compressed air plant 4 dynamometer 10 admission box 16 ethanol flow meter 5 power turbine 11 flexible conduit 17 ethanol reservoir 6 lpg fuel vessel 12 treatment duct fig. 2. experimental set-up showing the spraying system attached to the gas turbine. the experimental rig shown schematically in figure (2) is mainly a duct that inducing the ambient air inside to pass across the sprayed ethanol source and driving the treated air down to the gas turbine inlet. at the end of the spray chamber, an air assisted atomiser was installed to create a mist of very tiny ethanol droplets which increase the surface area of the liquid exposed to the air in order to enhance the mass and heat exchange process. a galvanised sheets box of 30 cm cube is used to store the ethanol and it has an external lagging to avoid any heat interactions with the ambient. a glass bulb flow meter is used to measure the time needed to consume 10 ml of ethanol from the bulb, see figure (3). the ethanol atomiser has an orifice diameter of (1.2 mm) , and it is working at a safe pressure of (4 bar). the atomization air is generated by a liba two-stage reciprocating compressor works under a maximum pressure of 10 bar, having a 100 litres accumulator. the gas turbine used in this study is a two-shaft t200d mini-gas turbine unit fabricated by didacta italia. the combustion chamber burns the lpg gaseous fuel that ignited by a spark plug. ethanol needs to be introduced in such a way that no disturbance is created within the air inflow. this task could be satisfied by means of inlet injection as ethanol easily mix and penetrate the bulk flow of air. the attachment of the gas turbine unit with the spraying system is done by adding the “admission box” which encloses the machine inlet matrix to decelerate and separate the nonevaporated droplets escaping out of the treatment duct before entering the unit, see figure (4). abdul satar j. al-saraf al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 5464 (2013) 58 fig. 3. ethanol reservoir with flow meter and control valves. as shown in figure (5), the t200d unit is equipped with a synoptic panel contains the main measuring instrument that built in it and covering the vital parts of the gas turbine cycle. the pressure gauges are all mechanically operated with a range of (0 to 10 bar) for high pressure side, while for low pressure side after the combustion chamber the gauges work with a range of (0 to 600 mbar). the temperatures are all digitally displayed with signal comes from probes inserted into air path around the cycle. the both turbines rotational speed are indicated by digitally displaying tachometers. the dynamometer output is indicated digitally in terms of electric current and voltage developed by the alternator connected to the power turbine via a toothed belt assembly. this output represents the electric power produced by the unit. the main lpg fuel has a mechanically operated pressure gauge indicating the supply pressure with a range of (0 to 4 bar), as well as, a rotary float meter measuring the lpg mass flow rate up to 3 g/s. fig. 4. set-up of the ethanol fuelled mini-gas turbine. variable power supply air preheater admission box air compressor flexible conduit combustion chamber treatment duct air thermostat atomization air pressure gauge ethanol flow control valve ethanol bulb flow meter air pressure regulating valve ethanol storage reservoir admission box abdul satar j. al-saraf al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 5464 (2013) 59 fig. 5. synoptic panel of the t200d mini-gas turbine. a 6000w air electric heater has been installed at the entrance of the spray chamber to control the induced air temperature. the electric heater is controlled by a thermostat with operating range of (30 to 120 o c). the thermostat is activated by a sensing bulb placed prior to the ethanol atomiser. a variable power supply unit ogawa seiki model sat-2030 with maximum current of 30 amp is used to supply the exact value of electric current needed to establish the intended inlet air temperature. this temperature is measured by an intelligent lutron model yk-2001 tm professional, type k, thermometer. the study comprises the performing of experiments on the gas turbine unit combined with the ethanol injection system in purpose of tracking the changes in the operational parameters of the gas turbine cycle as ethanol being sprayed in the intake air of the unit. 5.2. testing procedure the tests are initiated with running the machine on the conventional lpg fuel in the sequence described in reference [12]. each test is targeted to examine the engine performance under the intended operating condition. switching to dual fuel run needs firstly to reduce the lpg flow rate in accordance to the prescribed volume ratio. secondly, the ethanol fuel is to be supplied into the inlet air in the required volume ratio and brought the ethanol vapour into the combustion chamber. nevertheless, this process is very difficult since the two fuels are come from separate streams such that the combustion chamber acts as a mixing box for them. a good approximation is to deliver the two fuels in amounts determined on basis of the heating value to compensate the reduction in the heat liberated due to lower ethanol heating value. however, practically this is not enough because of the unexpected losses accompany the real engine run. slight changes in both fuels flow rates must be done very slowly to keep the volume mixing ratio while attaining the intended condition with the adequate total mass flow of the dual fuel. due to this prolonged complicated process, some deviations from the nominated volume ratios are to be accepted, although, these deviations were actually marginal. the maximum deviation recorded in the worst cases was on the lower limit of nominal 10% ethanol which gave a ratio of 9.74% representing a deviation of – 2.6%. on the other hand, the upper limit of nominal 20% ethanol in dual fuel gave a ratio of 21.2% representing a deviation of + 6.1%. however, all other tests were accomplishing volume ratios with deviations never exceeded %.51± . 6. results and discussion experiments were first conducted at five different inlet air temperatures namely, 23, 27, 35, 40 and 45 o c in order to demonstrate the impact of the air ambient temperature on the cycle performance. these tests were carried out under a constant load of 65% of the engine full load. abdul satar j. al-saraf al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 5464 (2013) 60 increasing inlet air temperature lowers the air mass flow due to the density reduction as shown in figure (6). the air mass flow has an average decrease of about 11% as the air temperature increased to 45 o c for all gas generator speeds. 15 30 45 60 ambient air temperature (c) 0.02 0.03 0.04 0.05 0.06 0.07 a ir m a ss f lo w ( k g /s ) 47000 rpm 50000 rpm 54000 rpm normal gas turbine load = 65 % gas generator speed: fig. 6. effect of ambient air temperature on the induced air mass flow. the effect of the ambient temperature on the power output is clearly described in figure (7). the output degrades with increasing ambient temperature due to the increase in compression work caused by higher delivery pressure and temperature. the maximum degradation in power was 30.2% of the power developed at 23 o c for corresponding ambient temperature of 45 o c measured at a gas generator speed of 47000 rpm. when the gas generator speed rose to 54000 rpm; the maximum reduction in power became 32.8% for the same corresponding ambient temperatures. figure (8) indicates the decrease in overall efficiency with higher ambient temperature resulted from the reduction in power output. the maximum reduction of 25% was recorded at ambient temperature of 45 o c with 47000 rpm, nevertheless, when gas generator speed reached 54000 rpm; the reduction became 20% as the heat rate was reduced avoiding the limit of inlet turbine temperature. 15 30 45 60 ambient air temperature (c) 0.0 0.1 0.2 0.3 0.4 0.5 0.6 o u tp u t p o w e r (k w ) 47000 rpm 50000 rpm 54000 rpm normal gas turbine load = 65 % gas generator speed: fig. 7. effect of ambient air temperature on the engine power output. 15 30 45 60 ambient air temperature (c) 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 o ve ra ll e ff ic ie n cy ( % ) 47000 rpm 50000 rpm 54000 rpm normal gas turbine load = 65 % gas generaroe speed: fig. 8. effect of ambient air temperature on the cycle overall efficiency. when detecting the effect of inlet ethanol injection on the cycle performance, experiments were conducted at two eth/lpg fuel ratios of 10 and 20% by volume with air under 45 o c. the tests carried out under the same loading level of 65% on the engine as explored in figures (9) to (11). abdul satar j. al-saraf al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 5464 (2013) 61 6000 10000 14000 18000 22000 power turbine speed (rpm) 0.0 0.1 0.2 0.3 0.4 0.5 0.6 o u tp u t p o w e r (k w ) 0.0 % eth 10 % eth 20 % eth tamb = 45 c load = 65 % eth/lpg ratio: fig. 9. relationship between engine power output and power turbine speed at different eth/lpg ratios. 6000 10000 14000 18000 22000 power turbine speed (rpm) 0 10 20 30 40 50 60 70 80 sp e ci fi c fu e l c o n su m p ti o n ( k g /k w h ) 0.0 % eth 10 % eth 20 % eth tamb = 45 c load = 65% eth/lpg ratio: fig. 10. relationship between specific fuel consumption and power turbine speed at different eth/lpg ratios. the evaporation of injected ethanol brings the inlet air temperature to be reduced, hence, increasing the density at the compression commencement. this effect will certainly decrease the delivery air temperature, as well as, the work needed for the compression. therefore, increasing ethanol injection rate is coupled with increasing the power output of the engine as a result of the higher mass flow, see figure (9). at 45 o c ambient air temperature the ultimate power enhancement recorded was 6.4% with eth/lpg ratio of 10%. but when the ratio has increased to 20%, the enhancement reached 19.2% compared to that of normal engine run on lpg alone. with the increased ethanol content in the compressed air, the sfc worsens as more fuel should be supplied to maintain the same power output, due to the lower heating value of ethanol in the fuel mixture. the deterioration in the sfc ranked a level of 13.4 and 22% for eth/lpg ratio of 10 and 20% respectively, compared to the pure lpg consumption, as clarified in figure (10). 6000 10000 14000 18000 22000 power turbine speed (rpm) 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 o ve ra ll e ff ic ie n cy ( % ) 0.0 % eth 10 % eth 20 % eth tamb = 45 c load = 65 % eth/lpg ratio: fig. 11. relationship between overall efficiency and power turbine speed at different eth/lpg ratios. 25 50 75 100 percent of full load 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 o ve ra ll e ff ic ie n cy ( % ) 0.0 % eth 10 % eth 20 % eth tamb = 45 c nt = 12000 rpm eth/lpg ratio: fig. 12. effect of engine loading on overall efficiency at different eth/lpg ratios. abdul satar j. al-saraf al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 5464 (2013) 62 the lower heating value of ethanol requires more fuel to be burned, thus, more energy to input and that reflects on the overall efficiency as shown in figure (11). the average reduction in efficiency was about 9% for the eth/lpg ratio of 10%, whilst, for the ratio of 20%; the reduction reached 14.4% with respect to pure lpg run. understanding the impact of engine loading on the dual-fuel gas turbine, requires tests to be conducted at four steps of loading namely, 40, 50, 65 and 90% of the engine full load. those were executed to maintain a constant power turbine speed of 12000 rpm. figure (12) shows the variation of overall efficiency with engine loading at air ambient temperature of 45 o c. like before, at light and medium loading range, the efficiency has reduced with increasing eth/lpg ratio. but, when going towered the higher engine loading with more fuel consumption, the overall efficiency was slightly improved due to the extra ethanol in compressed air, whose contains oxygen atom within its chemical structure that help aiming complete fuel combustion. the improvement in efficiency was 6% with eth/lpg ratio of 10%, nevertheless, at a ratio of 20% the improvement is only reached 3.1% when going beyond 70% of the full engine load. 7. conclusions • the air mass flow has an average decrease of about 11% as the air temperature increased from 23 to 45 o c for all gas generator speeds. • with the ambient temperature increased from 23 to 45 o c, the maximum degradation in power output was 32.8% when speed reached 54000 rpm. at that speed, the overall efficiency suffered a maximum reduction of 20% with respect to normal lpg run. • adding ethanol with eth/lpg ratio of 20% by volume made an enhancement in the power output of 19.2%, while overall efficiency went down by 14.4%. this ethanol concentration brings an increase in sfc of 22% compared to that of lpg normal run, all under 45 o c air temperature. • raising the engine loading beyond 70% led the dual-fuel engine to excel the normal lpg engine by 6 and 3.1% at eth/lpg ratios of 10 and 20% respectively. nomenclature symbols c specific heat capacity kj/kg k f correction factor h manometer reading mm h2o h lower heating value of fuel kj/kg i electric current amp m& mass flow rate kg/s n rotational speed rev/min p pressure kn/m 2 q& heat power kj/s s specific entropy kj/kg k t absolute temperature k v specific volume m 3 /kg v volume m 3 w specific work done kj/kg γ ratio of specific heats η efficiency θ time s ρ density kg/m 3 φ electric voltage volt subscripts a air amb ambient condition c compressor c corrected value e electric f fuel g gas generator turbine ov overall p constant pressure process t power turbine 0 stagnation condition 1 compressor inlet 2 compressor outlet abbreviations bmep brake mean effective pressure eth ethanol ge general electric company lpg liquefied petroleum gas naca national advisory committee for aeronautics sfc specific fuel consumption abdul satar j. al-saraf al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 5464 (2013) 63 8. references [1] costa r.c. & sodre j. r., “hydrous ethanol vs. gasoline-ethanol blend: engine performance and emissins” elsevier, jour. of fuel, vol. 89, pp: 287-293, feb., 2010. [2] mendez c.j., parthasarathy r.n., gollahalli s.r., “performance and emission characteristics of a small-scale gas turbine engine fuelled with ethanol/jet-a blends”, aiaa aerospace sciences meeting, 12th jan., 2012, nashville, tennessee. [3] schornick j.f., “use of biodiesel in the lm packages”, ge aero energy division, houston, texas usa, position paper #54, 2009. [4] pikunas a., pukalskas s., grabys j., “influence of composition of gasolineethanol blends on parameters of internal [5] [6] combustion engines”, jour. of kones, internal combustion engines, vol. 10, pp: 3-4, 2003. [7] boyce m. p., “gas turbine engineering handbook”, 2nd edition, gulf professional publishing, elsevier (usa), 2001. [8] jones w. l., engelman h. w., “experimental investigation of thrust augmentation of 4000-pound-thrust centrifugal-flow-type turbojet engine by injection of water and alcohol at compressor inlets”, naca rm no. e7j19, 14th may 1948, washington (usa). [9] danjou k., yamamoto t., sugiyama h., “enhancing efficiency of methanol fuelled gas turbine”, international symposium on alcohol fuels, 1988, tokyo, japan. [10] jozsa v., “application of bioethanol in gas turbines”, periodica polytechnic, mechanical engineering , vol. 55, part 2, pp: 91-94, 2011. [11] do nascimento m.r., dos santos e.c., “biofuel and gas turbine engines”, federal university of itajuba-unifei, 2010, brazil, www.intechopen.com [12] bevill k., “ge power turbines with ethanol in brazil”, ethanol producer magazine, sept. 23rd, 2010, www.ethanolproducer.com. [13] cohen h., rogers c., saravanamuttoo h., “gas turbine theory”, textbook, si units, 4th edition, 1996. [14] “t200d two-shaft gas turbine unit”, user’s manual and exercise guide, didacta italia, 2001. appendix specifications of t200d twin-shaft gas turbine unit [12] compressor centrifugal turbines radial inflow power output 1.5 kw @ ng/nt : (55000/21000) rpm compressor speed 60000 rpm max. free turbine speed 23000 rpm max. overall pressure ratio 1.3 / 1 max. firing temperature 700 – 750 o c max. fuel lpg, 3 g/s max. @ 2 bar max. )2013( 5464، صفحة 4، العدد9مجلة الخوارزمي الھندسية المجلد الصراف جوادعبد الستار 64 بأضافة ا0يثانول الى الھواء الداخل تعزيز القدرة الخارجة لوحدة توربين غازي مصغرة للضاغطة **سھاد عبد الحميد الجميلي *عبد الستار جواد الصراف الجامعة التكنولوجية/ ئن والمعداتقسم ھندسة المكا** ،* dr_asjsaraf@uotechnology.edu.iq :البريد ا�لكتروني* s_jumaily@yahoo.com :البريد ا�لكتروني** خ:صةال . t200dثنائي المحور تم إجراء دراسة تجريبية حول إستغ8ل تقنية حقن ا�يثانول في ھواء الدخول بھدف تقييم أثرھا على إداء ماكنة توربين غازي 45عند درجة حرارة محيط قدرھا %32.8سجل بحدود أقصى تردي للقدرة الخارجة o c . يثانول عند درجة الحرارة تلك بنسبة حجمية�أضافة ا الثنائي حققت -إستھ8ك الوقود النوعي لماكنة الوقود. مقارنة مع الماكنة التقليدية %19.2يجلب زيادة للقدرة الخارجة بحدود %20غاز قدرھا \أيثانول ، لكن مع زيادة التحميل %20غاز \عند نسبة أيثانول %14.4الكفاءة ا�جمالية تعاني أنخفاضاً أقصى قدره . أعلى من إستھ8ك الغاز الصرف %22مستوى لنسبة خلط الوقود تلك للحفاظ على %3.1الثنائي تتفوق على الماكنة التقليدية بتحسن كفائتھا بمقدار نة الوقودمن حمل الماكنة الكلي؛ فأن ماك %70لمافوق . دقيقة\دورة 12000سرعة ثابتة لتوربين القدرة مقدارھا (microsoft word 67-76\343\345\344\317) 1 al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 14, no. 1, march, (2018) p.p. 67-76 neural network modeling of cutting force and chip thickness ratio for turning aluminum alloy 7075-t6 mohanned mohammed h. al-khafaji department of production engineering and metallurgy/ university of technology/ baghdad/ iraq email: mohannedalkhafaji@hotmail.com (received 15 march 2017; accepted 31 october 2017) https://doi.org/10.22153/kej.2018.10.004 abstract the turning process has various factors, which affecting machinability and should be investigated. these are surface roughness, tool life, power consumption, cutting temperature, machining force components, tool wear, and chip thickness ratio. these factors made the process nonlinear and complicated. this work aims to build neural network models to correlate the cutting parameters, namely cutting speed, depth of cut and feed rate, to the machining force and chip thickness ratio. the turning process was performed on high strength aluminum alloy 7075-t6. three radial basis neural networks are constructed for cutting force, passive force, and feed force. in addition, a radial basis network is constructed to model the chip thickness ratio. the inputs to all networks are cutting speed, depth of cut, and feed rate. all networks performances (outputs) for all machining force components (cutting force, passive force and feed force) showed perfect match with the experimental data and the calculated correlation coefficients were equal to one. the built network for the chip thickness ratio is giving correlation coefficient equal one too, when its output compared with the experimental results. these networks (models) are used to optimize the cutting parameters that produce the lowest machining force and chip thickness ratio. the models showed that the optimum machining force was (240.46 n) which can be produced when the cutting speed (683 m/min), depth of cut (3.18 mm) and feed rate (0.27 mm/rev). the proposed network for the chip thickness ratio showed that the minimum chip thickness is (1.21), which is at cutting speed (683 m/min), depth of cut (3.18 mm) and feed rate (0.17 mm/rev). keywords: machining forces, chip thickness ratio, neural network, optimization, turning operation. 1. introduction the turning process is among the most significant cutting operation. it would once generate a variety of cylindrical products like solid, hollow, profile shafts and threads, etc. due to its important, a lot of scientists considered the parameter which impacting the process either to generate a good finished product, improve tool life or both. additionally, they examined the power usage reduction and the production time [1]. the machining force ���� in turning operation is a three-dimensional vector. three components represent it, namely, the cutting force���) which is in the direction of cutting axis, the passive force ���� in the direction of radial axis and feed force ���� in the direction of feed axis as shown in fig. 1. the cutting force has the biggest value in the three force components. several researchers learned such components and taking into accounts the effect of cutting variables. stachurski, et al. [2] utilized a power polynomial to model the cutting force during turning steel c45. astakhov and xiao [1] applied mathematical models to estimate the cutting forces during machining two materials, aerospace aluminum alloy 2024 and t6aisi bearing steel e52100. agustina, et al. [3] implemented a design of experiment to evaluate the impact of cutting factors to the cutting force when turning aluminum alloy (uns a97075) in dry conditions. they examined the influence of micro grove size and shape on the cutting temperature, cutting force and tool wear. c.x.yue, et al. [4] produced a three-dimensional model by using mohanned mohammed h. al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 6776 (2018) 68 abaqus/explicit to simulate the cutting operation of hardened steel gcr15. for their model the cutting temperature, surface residual stresses, cutting force and the side flow were investigated. the chip thickness ratio (ctr) gives essential indication for the cutting process stability. it can be explained as the ratio relating the chip thickness to the undeformed chip thickness. it is usually greater than unity (ctr>1) [5]. through the definition, the higher ctr means that the chip is thicker. the reason is the limitation to the chip movement, that in turns, can cause rise in the machining power and vice versa. santos, et al. [5] researched the machining force (fu), chip thickness ratio (ctr) and chip disposal during turning ductile (1350-o grade) and high strength (7075-t6 grade) aluminum alloys at different cutting conditions. astakhov and shvets [6] investigated the chip compression ratio with several cutting parameters. fig. 1. machining force and its components. in recent years, the scientific approaches such as neural network, fuzzy logic, genetic algorithm, ant colony or combinations of them, are used to model nonlinear, complicated and multi parameters system. in addition, they are used in the optimization of such systems. the neural network is miming human brain. it consists of an input layer to presents data to the network, output layer to produces the network response, and one or more hidden layers. the hidden and output layers’ topology, weights and activation functions are the network characterization. a neural network is trained with various data sets and tested with other testing data sets to reach an optimum topology and weights. once the network is trained, it can be used for prediction, simulation, monitor and control complicated system [7]. sick [8], used the neural network to estimate the development of tool wear. sharma, et al., [9] utilize the neural network to model the cutting force and surface roughness as a response to the approach angle, cutting speed, feed rate and depth of cut. chen, et al., [10] constructed nested artificial neural network. their model consists from two networks, the first one is the enclosed network which take the cutting parameters to predict the cutting force and tool vibration, and the second is the output network which take the outputs of the first network and the cutting parameters as inputs and give the surface roughness as output. sangwana, et al., [11] optimized the surface roughness during turning of ti-6al-4v titanium alloy by integrating feed forward neural network and the genetic algorithm. al-khafaji, et al., [12] applied levenberg marquardt algorithm for backpropagation training algorithm to train four feed forward neural network. their networks were constructed to different insert type. the network takes the cutting speed, feed rate and depth of cut as input and predict the surface roughness. these networks are used to optimize the cutting parameters for minimizing surface roughness. mia and dhar, [13] presented an artificial neural network based model to predict the surface roughness of en 24t steel in turning operation. their model take the cutting speed, feed rate, material hardness and the machining environment, coolant or dray conditions, as input. the model output was surface roughness. this paper aims to build neural network model to correlate the cutting variables, cutting speed (��), depth of cut ( ), and feed rate ( ), to the machining force (��) and the chip thickness ratio during machining aluminum alloy 7075-t6. 2. experimental data the implemented experimental data are conducted by santos, et al. [5]. the workpieces are artificially aged aluminum alloy 7075-t6, they are cylindrical extruded bars (ø 101×2,000 mm) in dimension. their chemical composition is 1.20– 2.00 % cu, 0.40 % si, 2.10–2.90 % mg, and 5.10– 6.10 % zn. the experiments had been executed on cnc lath machine romi multiplic 35d applying 6% concentration of soluble oil with 360 l/h. the cutting tool implemented comes with iso designation of (tcgt16t308-az hti10) which is cemented carbide inserts. the tool holder utilized in the experiments is made by mitsubishi which has a designation of (stgcr2020k16z). the applied tool geometries have been: rake angle, �� 15°; mohanned mohammed h. al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 6776 (2018) 69 relief angle, �� 7°and approach angle, �� 90°. these angles have been estimated after installing the tool on the tool holder. the forces measuring system is made up from three elements, a force sensor which is force dynamometer, a signal conditioning and usb 6251 data acquisition board. the force sensor and a signal conditioning element are made by kistler company both have model no. (9265b) and (5019b), respectively. the usb 6251 data acquisition board made by national instruments controlled by labview® 9.0 software were applied for data recording. when the cutting conditions are getting a steady-state stage, the data recorded for a 10s interval at 6khz as sample rate. the system has been calibrated prior to conducting the experiments. the machining variables that will be considered in this paper are cutting speed (��� depth of cut � � and feed rate � ). five level were given for each variable, for cutting speed, ��, (117, 200, 400, 600, and 683 m/min), for depth of cut, , (0.38, 1.00, 2.50, 4.00, and 4.62 mm) and for feed rate, , (0.170, 0.200, 0.275; 0.350; and 0.380 mm/rev). the experimentation output were cutting force, ��, passive force, ��, feed force, ��, and chip thickness ratio, ���.the experimental data shown in table 1. the tests no. 8, 9, 10 and 11 shown in the table1 duplicated so that average of their results has been utilized in the modeling. 3. neural netowrk modelling the feedforward networks have number of neurons in their layers, the layers arrange sequentially. the outputs of one layer are inputs to the next layer neurons. as mentioned in advance that the feedforward neural network consists from one or more hidden layer. these layers are characterized by their activation function and neurons number [13]. the network training is a process to adjusts the networks’ weights to reach the minimum error between the network output and the target, the experimental data. the most common algorithm used to train neural network, adjusting weights, is the backpropagation algorithm. [7]. table 1, machining experimental results taken from santos, et al. [5] no input measured ��� � �� � ! (mm) " ��� #$%� &��'� &(�'� &"�'� )*+ 1 117 2.5 0.275 564 -24.9 158 1.32 2 200 4 0.2 749 -1.9 233 1.69 3 200 4 0.35 1150 -23.1 222 1.71 4 200 1 0.2 167 -5.76 31.5 1.5 5 200 1 0.35 257 -11.4 30.5 1.96 6 400 4.6 0.275 923 -40.4 134 1.45 7 400 2.5 0.17 377 -9.5 133 1.48 8 400 2.5 0.275 518 -30.7 112 1.45 9 400 2.5 0.275 518 -31 113 1.45 10 400 2.5 0.275 522 -32.7 114 1.45 11 400 2.5 0.275 520 -27.9 115 1.45 12 400 2.5 0.38 636 -51.1 101 1.41 13 400 0.38 0.275 84.8 28.6 14 1.14 14 600 4 0.2 678 4.51 185 1.5 15 600 4 0.35 992 -28 167 0.75 16 600 1 0.2 153 -8.64 24.9 1.5 17 600 1 0.35 238 -19.1 11.8 1.61 18 683 2.5 0.275 491 -29.5 106 1.36 the radial basis function (rbf) neural networks type is fundamental categories of neural networks. the primary features of the rbf model are its efficiency, the implementation simplicity. in addition, good learning and generalization capabilities. the radial basis function network construction requires two different layers, a single hidden layer and the output layer. the hidden layer mohanned mohammed h. al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 6776 (2018) 70 has nonlinear processing neuron, which provides an alternative goal from that in the feedforward multilayer perceptron mlp network. the output layer has neurons to compute the scalar product of its inputs and provides the response of the network. the input space transformation to the hidden-unit space is nonlinear, whereas it is linear from the hidden-unit space to the output space. it can be concluded that the rbf network is a feedforward neural network with single hidden-layer [14]. the rbfs are generally proven to have universal approximation capabilities. they are suitable for solving pattern classification and function approximation problems because of their uncomplicated topology and their capability to show the learning proceeds in an explicit manner [14]. the hidden layer activation function in the radial basis neural network is radial function. the most radial basis function used is gaussian function. in a rbf network having k radial units in the intermediate layer and one output [15]. the weights connecting the hidden and output units are estimated either by the least mean square (lms) or the gradient descent method [14]. radial basis networks might need more neurons compared to standard feedforward backpropagation networks, although they can be designed with a less time that it takes to train standard feedforward networks. they operate most effective when many training vectors are implemented [16]. in this work a rbf neural network were used to model the cutting parameters against machining force components and chip thickness ratio. four models were constructed using matlab neural network toolbox. the input to all networks are cutting speed ��, depth of cut and feed rate . the first three networks’ responses are cutting force ��, passive force �� and feed force ��, respectively. whereas, the fourth network’s response is chip thickness ratio ���. as stated in advance the rbf network is like feedforward mlp network in architecture with only one hidden layer. the function, newrb, in matlab neural toolbox used in this work to generate the models networks is conducting it calculates the distance of network input from the weights’ matrix rows, rather than matrix multiplication as in mlp network. in addition, it multiplies the bias instead of adding it. therefore, the input of hidden layer ,-. neuron is computed by (1) [16] [17]. /01 23 − 5012. 701 ... (1) where, 3 is the input vector, 51 is the weights’ matrix and 71 is the bias. each weights’ matrix element is considered as center point, a point at which the net input is zero. whereas, the bias is used to scale the output of the hidden layer transfer function (the radial basis function) output either stretching or compressing it. in this paper the tool box function newrb is implemented to generate the radial basis neural network models. the network generated by this function use the gaussian function shown in fig. 2 as a transfer function and defined by (2) 801 9:;<= ...(2) an essential property of the gaussian function, it is local. which indicate that the output is near to zero if n moves extremely far in either direction from the center point. in addition, it is global function. it is opposed to the global sigmoid functions used in the multilayer perceptron mlp whose output remain near to 1 when the net input goes toward infinity. the output layer in rbf network is pure line given by (3) [16] [17] 8> ∑ 5@>8@1a@b1 + 7> …(3) where, d is the number of neurons in the hidden layer, 5> is the weights’ vector connecting the hidden layer and the output layer and 7> is the bias of the network output layer. the model of the proposed radial basis models is shown in fig. ٣ . the vector 3 in equation (1) is consist of three components which are cutting speed, depth of cut and feed rate. the number of hidden layer neurons (d� is 18 for all four models. the weights matrix 51 has size of 18 rows and 3 columns and the bias vector 71 has 18 elements. the 5> has 18 elements too. table 2 to table 5 show the network weights matrices and bias for ��, ��, �� and ��� models, respectively. it should be noted that the value of second layer bias 7> for ��, ��, �� and ��� networks are scalar values equal to (−1058.152), (−15.3309), (557.1898) and (0.8283), respectively. fig. 2. gaussian function. mohanned mohammed h. al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 6776 (2018) 71 fig. 3. the proposed neural network model. 4. results and discussion the networks outputs are extremely matching the experimental data. the correlation coefficient � is computed for all networks using equation (4) � a ∑ hi ;i:∑ h ∑ ; jka ∑ hi=:�∑ hi�=lka ∑ ;i=:�∑ ;i�=l … (4) all networks responses gave value of r equal to one. this is a perfect match. fig. 4-7) which showing the networks responses compared with the experimental data taken from santos, et al. [5] for ��, ��, ��, and ���, respectively. it can be seen from those figures that all networks outputs are perfectly coincide with the experimental data given by santos, et al. [5]. the machining force �� is the resultant of the three components as mentioned in advanced. it can be computed using equation (5). according to the perfect matching between experimental and networks outputs of the machining forces’ components, the machining force �� computed from the networks outputs is perfectly coincide with the experimental ��. fig. 8 shows the perfect match of the computed �� versus the experimental �� from santos, et al. [5]. �� j��> + ��> + ��> … (5) table 2, the &� network weights matrices and bias. no. mn on mp 1. 200 4.00 0.350 0.833 13961.3 2. 400 2.50 0.380 0.833 0 3. 600 4.00 0.350 0.833 11092.91 4. 400 4.60 0.275 0.833 1913.422 5. 117 2.50 0.275 0.833 1622.152 6. 683 2.50 0.275 0.833 1549.152 7. 200 1.00 0.350 0.833 3520.709 8. 600 1.00 0.350 0.833 3356.444 9. 200 4.00 0.200 0.833 -11940.5 10. 600 4.00 0.200 0.833 -9187.46 11. 400 2.50 0.170 0.833 -8603.13 12. 400 0.38 0.275 0.833 1079.067 13. 200 1.00 0.200 0.833 -2244.6 14. 600 1.00 0.200 0.833 -2096.74 15. 400 2.50 0.275 0.833 9977.41 16. 400 2.50 0.275 0.833 0 17. 400 2.50 0.275 0.833 0 18. 400 2.50 0.275 0.833 0 table 3, the &( network weights matrices and bias. no. mn on mp 1. 400 2.5 0.38 0.8326 0 2. 400 4.6 0.275 0.8326 -24.312 3. 400 0.38 0.275 0.8326 44.644 4. 683 2.5 0.275 0.8326 -14.169 5. 400 2.5 0.17 0.8326 1381.82 6. 117 2.5 0.275 0.8326 -9.569 7. 600 1 0.35 0.8326 -335.18 8. 200 4 0.35 0.8326 -683.21 9. 600 4 0.35 0.8326 -1047.9 10. 600 4 0.2 0.8326 1051.56 11. 200 4 0.2 0.8326 686.05 12. 200 1 0.35 0.8326 -177.49 13. 600 1 0.2 0.8326 336.650 14. 200 1 0.2 0.8326 184.293 15. 400 2.5 0.275 0.8326 -1387.3 16. 400 2.5 0.275 0.8326 0 17. 400 2.5 0.275 0.8326 0 18. 400 2.5 0.275 0.8326 0 mohanned mohammed h. al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 6776 (2018) 72 table 4, the &" network weights matrices and bias no. mn on mp 1. 200 4 0.2 0.833 189.7411 2. 400 2.5 0.17 0.833 1062.935 3. 600 4 0.2 0.833 389.2137 4. 117 2.5 0.275 0.833 -399.19 5. 400 4.6 0.275 0.833 -404.308 6. 683 2.5 0.275 0.833 -451.19 7. 200 1 0.2 0.833 -233.206 8. 600 1 0.2 0.833 150.9871 9. 400 2.5 0.275 0.833 -1456.21 10. 600 4 0.35 0.833 -772.317 11. 400 0.38 0.275 0.833 -525.381 12. 600 1 0.35 0.833 -693.28 13. 200 4 0.35 0.833 -520.967 14. 400 2.5 0.38 0.833 0 15. 200 1 0.35 0.833 -296.439 16. 400 2.5 0.275 0.833 0 17. 400 2.5 0.275 0.833 0 18. 400 2.5 0.275 0.8325 0 table 5, the )*+ network weights matrices and bias. no. mn on mp 1. 400 2.5 0.17 0.8326 0 2. 200 1 0.35 0.8326 15.3151 3. 200 4 0.35 0.8326 1.05552 4. 600 1 0.35 0.8326 3.96737 5. 600 4 0.2 0.8326 24.3887 6. 400 4.6 0.275 0.8326 0.59432 7. 683 2.5 0.275 0.8326 0.53165 8. 117 2.5 0.275 0.8326 0.49165 9. 400 0.38 0.275 0.8326 0.28587 10. 600 4 0.35 0.8326 -24.091 11. 200 1 0.2 0.8326 -14.408 12. 600 1 0.2 0.8326 -3.2356 13. 400 2.5 0.275 0.8326 2.88848 14. 400 2.5 0.38 0.8326 -2.3251 15. 200 4 0.2 0.8326 -0.1788 16. 400 2.5 0.275 0.8326 0 17. 400 2.5 0.275 0.8326 0 18. 400 2.5 0.275 0.8326 0 these networks are used to optimize the cutting parameters that produce lowest machining force and chip thickness ratio. to do that, a matlab function has been written. the function creates two three-dimension arrays with (60, 60, 60) in size and initialized with zeros. the first array stores the results of �� and the second stores ���. in addition, its creates three vectors using the linspace matlab function. each vector has 60 elements for the three parameters cutting speed, depth of cut and feed rate. the range of the cutting speed vector is (117 – 683) m/min, for depth of cut is (0.38 – 4.62) and for feed rate is (0.170 – 0.380). then it performs loops to execute the networks with different parameters. the optimum parameters are founded by searching for minimum �� and minimum ��� arrayes. table 6 presents the optimum parameters that gives lowest �� and ���. the optimum parameter for both the �� and ��� are differ only in the feed. a surface drawn when taking the optimum cutting speed value as constant and changing the remaining for both the computed �� from the networks output and ��� are shown in fig. 9 and fig. 10, respectively. the square correlation coefficients of the proposed models are compared to those given by santos, et al. [5] as shown in table 7. table 6, the optimum parameters and their corresponding optimum values from &q and )*+ �� r � �� s !���� " ��� #$%� optimu m value �� 683 3.18 0.27 240.46 n ��� 683 3.18 0.17 1.21 table 7, rbf neural network tp versus tp from [5]. +p "u# &q +p "u# )*+ proposed rbf networks 1 1 results from santos, et al. [5] 0.998 0.9661 fig. 4 the neural network for &� response against the experimental data from santos, et al. [5]. mohanned mohammed h. al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 6776 (2018) 73 fig. 5 the neural network for &( response against the experimental data from santos, et al. [5]. fig. 6. the neural network for &" response against the experimental data from santos, et al. [5]. fig. 7. the neural network for ctr response against the experimental data from santos, et al. [5]. fig. 8. the &q computed from the networks outputs against the experimental data from santos, et al. [5]. fig. 9. &q surface when cutting speed is (683 m/min) fig. 10. )+* surface when the cutting speed is (683 m/min). mohanned mohammed h. al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 6776 (2018) 74 5. conclusion this study provided an experimental investigation, via radial basis function rbf network modeling, to estimate the affect of cutting parameters. (cutting speed, depth of cut and feed rate) on machining force (fu) and chip thickness ratio (ctr) during turning of high strength aluminum alloy 7075-t6. the primary conclusions of the investigation are given following: 1. the proposed rbf networks showed an extreme match to the experimental data and the computed correlation coefficients were equal one. additionally, those networks were used to optimize the cutting process and obtain the optimum cutting parameters. 2. the proposed methodology based on rbf neural network modeling can effectively overcome any complicated function approximation with more than two inputs. 3. the outcome also revealed that the effectiveness of the developed networks was better compared to existing using genetic algorithm (ga). the present study for optimizing the cutting process is anticipated to open two directions which can be suggested to continue this work. the first is to investigate the effect of more cutting parameters, which include cooling liquids and angles of cutting tools, on machining force and chip thickness ratio. the second possible direction is to integrate a neural network with fuzzy logic to solve a more complicated function approximation models. notation depth of cut 71 network first layer bias vector 7> network second layer bias vector ��� chip thickness ratio feed rate �� cutting force �� passive force �� feed force �� machining force 3 network input vector � correlation coefficient �� cutting speed 51 network first layer weights matrix 51 network first layer weights matrix 6. references [1] v. p. astakhov and x. xiao, "a methodology for practical cutting force evaluation based on the energy spent in the cutting system," machining science and technology, vol. 12, no. 3, pp. 325-347, 2008. 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[17] m. t. hagan, h. b. demuth, m. h. beale and o. d. jesús, neural network design, 2nd edition ed., oklahoma: oklahoma state university, 2014. )2018( 67-76، صفحة1د، العد14دجلة الخوارزمي الهندسية المجلم مهند محمد حسين 76 نمذجة قوة القطع ونسبة سمك النحاتة باستخدام الشبكات العصبية اثناء خراطة سبيكة األلمنيوم 7075-t6 مهند محمد حسين الخفاجي العراق /بغداد/ / الجامعة التكنولوجيةقسم هندسة اإلنتاج والمعادن mohannedalkhafaji@hotmail.com البريد االلكتروني: الخالصة القطع واستهالك الطاقة ودرجة ةتؤثر الكثير من المتغيرات على عملية القطع والتي يجب دراستها. ومن هذه المتغيرات الخشونة السطحية وعمر عد معقدة وال خطية بسبب هذه العوامل. إن الهدف من هذا البحث هو دحرارة القطع ومركبات قوى التشغيل وتآكل العدة ونسبة سمك النحاتة. ان عملية القطع تع ة سمك النحاتة. ببناء نماذج من الشبكات العصبية لتمثيل العالقة بين متغيرات القطع (سرعة القطع وعمق القطع ومعدل التغذية) وقوة التشغيل وكذلك مع نس ذلك تم فضالعنث شبكات عصبية نصف قطرية لكٍل من قوة القطع والقوة السلبية وقوة التغذية، . تم بناء ثالt6-7075عملة الخراطة اجرية لسبيكة األلمنيوم ءمعدل التغذية). تم مقارنة أداالقطع وانشاء شبكة نصف قطرية لنمذجة نسبة سمك النحاتة. ان مدخالت جميع الشبكات هي ظروف القطع (سرعة القطع وعمق لعالقة وكذلك تم حساب معامل ا اتام اتطابقمع التجارب العملية وأعطت غيل (قوة القطع والقوة السلبية وقوة التغذية) لمركبات قوة التش الشبكات (مخرجات) بكات شمعامل االرتباط مساٍو للواحد ايضاً، بالمقارنة مع النتائج العملية. ان هذه الها لنسبة سمك النحاتة كان ؤتم بناوكذلك الشبكة التي وجد بأنه مساٍو للواحد. أظهرت نتائج النماذج بإن افضل قوة تشغيل يمكن التي بدورها تعطي اقل قوة قطع وأقل نسبة سمك النحاتة.وظروف قطع أفضلاستخدمت إليجاد )نماذج(ال ملم/دورة). وأظهرت الشبكة ٠٫٢٧ملم) و معدل تغذية (٣٫١٨م/د) و عمق القطع ( ٦٨٣نيوتن) عندما تكون سرعة القطع ( ٢٤٠٫٤٦الحصول عليها هي ( ملم) و معدل تغذية ٣٫١٨م/د) وعمق قطع ( ٦٨٣عة القطع () عندما تكون سر١٫٢١اقل نسبة يمكن الحصول عليها هي (إن المقترحة لنسبة سمك النحاتة .ملم /دورة) ٠٫١٧( <4d6963726f736f667420576f7264202d20c7cee1c7d520e6c7edc7e320e6e4e6d1203135342d313434> 1 al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 14, no. 1, march, (2018) p.p. 145155 design of hybrid neural fuzzy controller for human robotic leg system ekhlas h. karam* ayam m. abbass** noor s. abdul-jaleel*** *, **department of computer engineering/ university of al-mustansyria ***department of electrical engineering/ university of al-mustansyria *email: ekhlashameed@yahoo.co.uk **email: ayammohsen@yahoo.com ***email: mail_ns1@yhoo.com (received 10 january 2017; accepted 7 august 2017) https://doi.org/10.22153/kej.2018.08.007 abstract in this paper, the human robotic leg which can be represented mathematically by single input-single output (siso) nonlinear differential model with one degree of freedom, is analyzed and then a simple hybrid neural fuzzy controller is designed to improve the performance of this human robotic leg model. this controller consists from siso fuzzy proportional derivative (fpd) controller with nine rules summing with single node neural integral derivative (nid) controller with nonlinear function. the matlab simulation results for nonlinear robotic leg model with the suggested controller showed that the efficiency of this controller when compared with the results of the leg model that is controlled by pi+2d, pd+nid, and fpd-id controllers. keywords: fuzzy proportional derivative controller, matlab simulation results, nonlinear differential leg model, pid controller, single node neural controller. 1. introduction the classical robots are commonly used for industrial automation and use in applications that are remote from human life and activities. however, recently the usage of robots has been changed from industrial applications to helpful for human robot system. with increasing aging societies, robots that used to support human in his activities in daily environments such as in offices, homes, school and hospitals are expected. particularly, because of anthropomorphism, helpful design for humanity, application of positioning and movement, and so on, powerfully expected to manufacture of humanoid robots [1]. present control techniques to locomotion of robotic legged depends on centralized planning and path follow or corresponding motion pattern. central control is not available to the robotic help devices that make integration with humans, and correspond to predefined patterns strongly limits from user ability. by difference, biological systems show big legged ability even when the system of the central nervous is separated from spinal cord that belong to these legged, pointing that feedback controls of neuromuscular is harnessed for encoding stability, compatibility, and maneuverability into robotic legged systems [2]. currently, control systems design is done by a big number of requirements caused by augmentation of competition, requirements of environment, energy and the costs of components and the request for robustness, system of error tolerance. these considerations introduce extra ekhlas h. karam al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 145155 (2018) 146 needs for effective process modeling techniques. several systems are not agreeable to traditional modeling approaches, caused when the precision is not found, about the system having formal knowledge, caused from strong behavior for nonlinearities, big degree of suspicion, or variance characteristic of the time [3]. neural networks and fuzzy logic systems are recently used for different control problems with acceptable results. both the neural networks and fuzzy logic systems are general approximations caused several adaptive control strategies for nonlinear systems that used fuzzy logic systems, or neural networks have been introduced to get more control performance [4]. as two important strategies of artificial intelligence, fuzzy logic systems and artificial neural networks (anns) have several applications in different fields such as availability of product, control systems, diagnostic, observation, etc. they developed and became better throughout the years for adaptation of the rising requirements and the develop of technology. while these two controllers have been frequently used together, explain that the concept of a fusion began to take shape [5]. the neuro-fuzzy system is more efficient and more effective than either neural network or fuzzy logic system which has been widely applied in control systems, pattern recognition, medicine, expert system, and etc. the advantage of this controller is the dealing with it more quickly than other traditional controllers [6]. different types of neuro-fuzzy have been shown in the literature. these types can be determined depend on the structure of the neurofuzzy, the fuzzy model used, and the learning algorithm taken. on the first hand, corresponding to the neuro-fuzzy structure and learning algorithm, the most usually used and successful technique is the feed-forward and recurrent structure model using the bp learning algorithm. on the other hand, according to the fuzzy model taken, two types of fuzzy models are merged with a neural network to form a neuro-fuzzy. these two models are familiar as takagi and sugeno model and the mamdani-model. however, mamdani-model based nnf represent more obvious neuro-fuzzy systems compared with tsmodel based nnf [7]. a simple hybrid neural fuzzy controller is designed in this paper for human robotic leg model, this controller consist from single node neural integral derivative (nid) controller and single input single output fuzzy proportional derivative (fpd) controller with nine rules. the details for this design will be explained in the sections of this paper. 2. human robotic leg mathematical model the human robotic leg can by modeled depend on the relation between the input torque that generated by the muscle of the leg and the output of the angular rotation around the hip joint [8]. a simplified human robotic leg cylindrical model is shown in fig. 1. fig. 1. human a robotic leg cylindrical model [9]. the parameters of fig. 1 are defined by table 1. table 1, the parameters of human robotic leg model. the nonlinear equation of the dynamic model for the robotic human leg can be written as follows [9, 10]: � ��� ��� � � �� �� � � � � �� � ����� … (1) where: mg � � sinθ is the component of weight, d �� � is the damping torque and "��� ���# is the inertia torque. the state space for eq. (1) is: symbol description values tm torque supplied by dc motor d viscous damping 0.1nms/ra d j inertia around the hip joint 0.4 kgm2/s2 m mass of the leg 1 kg g acceleration due to gravity creates a nonlinear torque 9.81 l the length of the leg and the weight can be determine as l/2 0.5m ekhlas h. karam al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 145155 (2018) 147 $%&'%�' ( � ) 0 1 ,� & -& ./ �0 � �%&� , "1 0#2 3 %&%�4 � )0& 0 2 �� 5 � 61 07 3%&%�4 … (2) where: x1, x2 is robotic leg angular position and velocity respectively. eq. (1) can be linearized for small angle approximation, the � variation is small; therefore sinθ can assume equal � (i. e. sinθ � �� so eq. (1) becomes: � ��� ��� � � �� �� � � � � � ����� … (3) the linear transfer function of eq. (3) is given by: ��8� 9�8� � : ; 8�<= ;8<>?@ �; … (4) with parameter given by table 1, eq. (4) becomes: ��8� 9�8� � �.b 8�<c.c�b8<d.&e& … (5) this transfer equation has two complex poles (-0.0125+2.4761j, -0.0125-2.4761j) with damping ratio ζ=0.0050, the state space equations are: $%&'%�' ( � 3 0 1,6.131 ,0.0254 3 %&%�4 � 3 02.54 �� 5 � 61 07 3%&%�4 … (6) with unity step input, the time response of the leg linear and nonlinear model is shown in fig. 2. fig. 2. time response for linear and nonlinear model. this figure show that the leg model response is high oscillation under damped. in order to reduce the oscillation, a suitable velocity feedback gain (kv=3.74) is adding to plant leg transfer function and hence this function becomes: ��8� 9�8� � �.b 8�<�c.c�b<�.bjk�8<d.&e& � �.b 8�<l.m8<d.&e&…(7) the damping ratio for linear model becomes ζ=1.76, so the response of unity step input for this equation and for the nonlinear model become over damped as shown in fig. 3. fig. 3. time response for linear and nonlinear model with velocity feedback gain kv= 3.74 3. hybrid neural fuzzy controller design the block diagram for nonlinear robotic leg model with the suggested hybrid like neural fuzzy controller is shown in fig. 4. fig. 4. the block diagram for hybrid neural fuzzy controller for human robotic leg. the suggested hybrid controller consists from siso neural integral derivative (nid) and fuzzy proportional derivative (fpd) controller. the first step for design this controller is determine the proportional integral derivative (pid) controller for the robotic leg based on the linear model of the robotic leg. generally, the equation of the ideal pid controller with ideal form is given as: n��� � �op � jq 8 � o�����r��� … (8) where: e(s) is the error signal between the desired input and the leg output position, while kp, ki, and kd are proportional, integral and + ekhlas h. karam al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 145155 (2018) 148 derivative gain in respectively, the values of these parameters are determine by launching pid tuner method that provide by matlab simulink with some manual modification. eq. (8) can be written as: n��� � op "1 � & 9q8 � ���#r��� … (9) where: ti is integral or reset time, and td is derivative or rate time. in this paper, instead of ideal pid controller we use pi+2d and hence eq. (9) becomes: n��� � op "1 � & 9q8 � ��� � ���# r��� … (10) or n��� � op t�1 � ���� � � & 9q8 � ����ur��� … … (11) eq. (11) can be written as: n��� � op�1 � ����r��� � op v 1 �w� � ���x r��� � n&��� � n���� … (12) the steps for designing the suggested controller will be demonstrate in the following sub sections. 3.1 fuzzy proportional derivative controller design the first part of eq. (12) is ideal pd controller as given by: n&��� � op�1 � ����r��� … (13) this equation is considered as input to the siso fuzzy controller as shown in fig. 5 after remove kp as given by: yw��� � �z��"1 � �� � ��# [���� … (14) fig. 5. fuzzy pd logic controller. the saturation function is used to limit any input signal to be between (n to –n), k] � kp ×o8 where ks is selected gain such that the value of kf should be equal to magnitude of the input signal, for example if the input is step with magnitude 10, then kf should be equal to10. usually, fuzzy logic theory deals with uncertain or imprecise situation. a variable in fuzzy logic has sets of values which are characterized by linguistic expressions, such negative, zero, positive, etc. these linguistic expressions are represented numerically by fuzzy set and it is characterized by membership function that varies from [0 to 1], which given element can be a member of any fuzzy set [11]. in general, the fuzzy controller design consists from three parts: 3.1.1. fuzzification the input (crisp) data is fuzzified according to a selected membership functions. the input and output membership are shown in fig. 6. (a) ekhlas h. karam al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 145155 (2018) 149 (b) fig. 6. membership function for, (a) input variable, (b) output variable. 3.1.2. rule base the knowledge base of the fuzzy logic consists of a set of fuzzy if (the satisfied conditions set) then (the inferred consequence set) rules which themselves consist of linguistic set, associated variables with inputs, outputs and fuzzy operators like or and and [12]. the quantitative if-then rules of our fuzzy controller are described as: r1: if ui(t) is m1 then uf(t) is m1 r2: if ui(t) is m2 then uf(t) is m2 r3: if ui(t) is m3 then uf(t) is m3 r4: if ui(t) is m4 then uf(t) is m4 r5: if ui(t) is m5 then uf(t) is m5 r6: if ui(t) is m6 then uf(t) is m6 r7: if ui(t) is m7 then uf(t) is m7 r8: if ui(t) is m8 then uf(t) is m8 r9: if ui(t) is m9 then uf(t) is m9 where: m is linguistic terms of antecedent fuzzy set, they mean m1= mf1, …, m9=mf9. the universe of discourse from -1.2 to 1.2 and from –20 to 20 for the input and the output membership function in respectively as shown in fig. 6. 3.1.3. defuzzification in this step, the center of mass (com) formula is used to defuzzify the law of the fuzzy controller. 3.2 neural integral derivative controller design a neural network is an interconnected network of nodes, working manner similar neurons in the human brains. each neurons contains a link collector that collects weighted with the shift income to form a numerical output of neuron, which is considered as lacking in movement with neural network fnn (x), where x …… ,r5. multi-layer perception (mlp) and radial basis function (rbf) networks are the common traditional neural networks [13]. in this paper (mlp) network is used, which is consist from three layers (input layer, hidden layer and output layer) as shown in fig. 7. fig. 7. the single node of the mlp where: i is the neuron number and xk is the input where k=1, …., k. (ni) is the result of multiplied the inputs by weights which is summed with each other with the bias term bi. this result becomes the input of the activation function (g). this function is considered to be a relay function. the sigmoid function or tangent hyberbolic (tanh) ekhlas h. karam al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 145155 (2018) 150 are widely used rather than the relay function [13]. the tangent function is given as: tanh�%� � &bcde &<cde … (15) in this paper our neural design is only single node of mlp networks with single input without delay, the integral derivative (id) is consider as input to this neural controller as shown in fig. 8, the output of neural network is multiply by proportional gain kp, manual train is used to determine the value of the bias and weight. fig. 8. single input-single output nid controller 4. simulation results and discussion in this section, different simulations for the nonlinear robotic leg model with (pi+2d, pd+nid, fpd+id, and the suggested fpd+nid) are carried out for step and multi-step input. the matlab simulink connection for the nonlinear leg model with the suggested controller is shown in fig. 9. fpd+nid. (a) (b) (c) fig. 9. matlab simulink connection for the robotic leg with the suggested hybrid controller; (a): complete connection; (b): neural network connection; (c): nonlinear leg model connection the controller's parameters are given by table 2. table 2, controller parameters. kp ti td ki kd wi bi 14 2 0.0357 24 0.5 0.1 0.1 the different simulations are presented as follows: i. simulation (1): in this simulation, the controlled robotic leg is tested by step input with magnitude 2 and the results of this case (angular position, velocity, error, and control signal) which are given in fig. 10 show that the position and velocity tracking is fairly good with nearly zero steady state error for all controller specially the our suggested fpd+nid controller. (a) weight 1 out tansig netsum .1 bias .1 1 in thetadot the ta torque input u(1) u(2) u(3) u(4) u(5) u(6) 2 out2 1 out1 -cmgl/2 .4 j 1 s integrator1 1 s in tegrator .01 d interpreted matlab fcn ((-u(3)*u(4))-(u(2)*sin (u(5)))+u(6))/u(1) 1 in1 ekhlas h. karam al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 145155 (2018) 151 (b) (c) (d) fig. 10. simulation results for robotic leg controlled by (pi+2d, pd+nid, fpd+id, fpd+nid) with step input of mag.2: (a) angular position; (b) angular velocity; (c) error signal; (d) control signal ii. simulation (2): in this simulation, the controlled robotic leg is tested by unity step input with nonlinear sinusoidal disturbance (dis=0.1sin(20t)) in addition to 10% parameter uncertainty in j, d, and m parameters are introduce during the simulation period. the results of this case are illustrate in fig. 11, these results show that the robotic leg is remain stable even with disturbance and uncertainty with very small steady state error and the disturbance is remove from the response of the angular position while it is not rejected very well from the response of the velocity see fig.11 b. (a) (b) (c) ekhlas h. karam al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 145155 (2018) 152 (d) fig. 11. unity step simulation results with nonlinear sinusoidal disturbance and parameter uncertainty: (a) angular position; (b) angular velocity; (c) error signal; (d) control signal. . iii. simulation(3): in this simulation, the controlled robotic leg is tested by multi step input without disturbance or parameter uncertainty as shown in fig. 12, and the results for this simulation are shown in fig. 13, fig.14, fig.15, and fig.16, these results show when sudden change occur in input signal and hence the mathematical model of robotic leg is nonlinear, the system become unstable with pi+2d, pd+nid, and fpd+id controllers while it remain maintain the stability with efficient performance with the suggested fpd+nid controller (nearly zero steady state error with no overshoot and fast settling time). fig. 12. multi-step input of mag.2. (a) (b) fig. 13. simulation results for robotic leg controlled with pi+2d and multi-step input of mag.2: (a) angular position, (b) error signal. (a) ekhlas h. karam al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 145155 (2018) 153 b)( fig. 14. simulation results for robotic leg controlled with pd+nid and multi-step input of mag.2: (a) angular position, (b) error signal. (a) (b) fig. 15 simulation results for robotic leg controlled with fpd+id and multi-step input of mag.2: (a) angular position, (b) error signal. (a) (b) fig. 16. simulation results for robotic leg controlled with fpd+nid and multi-step input of mag.2: (a) angular position, (b) error signal. 5. conclusion a simple hybrid neural fuzzy controller is designed to improve the performance of human robotic leg model which is siso. this controller consists from fuzzy proportion derivative (fpd) controller and single node neural integral derivative (nid) controller. the different simulation results with / without parameter uncertainty and nonlinear disturbance show that the suggested fpd+nid controller is better than pi+2d, pd+nid and fpd+id controllers. ekhlas h. karam al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 145155 (2018) 154 6. references [1] kenji kaneko, shuuji kajita, fumio kanehiro, kazuhito yokoi, kiyoshi fujiwara, hirohisa hirukawa, toshikazu kawasaki, masaru hirata, and takakatsu isozumi, design of advanced leg module for humanoid robotics, project of meti, international conference on robotics automation, washington, dc, may, 2002. 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[6] a. aldair and w. j. wang, adaptive neuro fuzzy inference controller for full vehicle nonlinear active suspension systems, school of engineering and design, iraq j. electrical and electronic engineering, vol.6 no.2, 2010. [7] a. fahmy , a.m. abdel ghany, neuro-fuzzy inverse model control structure of robotic manipulators utilized for physiotherapy applications, ain shams engineering journal, 805–829, 2013. [8] chun htooaung, khinthandarlwin, and yin mon myint, modeling motion control system for motorized robot arm using matlab, world academy of science, engineering and technology 42, 2008. [9] abdur raquib ridwan, md. ibnea sina bony and ishtiza ibne azad, performance analysis of mpc in the control of a simple motorized nonlinear model of a robotic leg, international journal of computer applications (0975 – 8887), volume 54, no. 11, september 2012. [10] richard l. shell ernest l. hall, handbook of industrial automation, university of cincinnati cincinnati, ohio, new yourk, 2000. [11] nidhi k., simulation studies on hybrid fuzzy-pi controllers for dc motor control, master thesis of engineering in control & instrumentation, maharishi dayanand university, rohtak haryana, 2006. [12] c. yen, f. wen, and m. ouyang, nonlinear positioning compensator of a novel thin-disc ultrasonic motor using fuzzy sliding mode control, international journal of applied science and engineering, vol. 2, no. 3, pp. 257-276, 2004. [13] [heikki n. koivo, neural networks: basics using matlab, neural network toolbox, february 1, 2008. )2018( 144-154 ، صفحة1د، العد14دجلة الخوارزمي الهندسية المجلم اخالص حميد كرم 155 تصميم مسيطر هجين من الشبكة العصبية مع المسيطر الضبابي لنظام ساق االنسان اخالص حميد كرم* ايام محسن عباس** نور صفاء عبد الجليل*** *, ** قسم هندسة الحاسوب/ الجامعة المستنصرية *** قسم الهندسة الكهربائية/ الجامعة المستنصرية ekhlashameed@yahoo.co.uk* البريد االلكتروني: ayammohsen@yahoo.com** البريد االلكتروني: mail_ns1@yhoo.com*** البريد االلكتروني: الخالصة ) sisoاحادي االخراج (خطي احادي االدخالالطة النموذج التفاضلي غير سافي هذا البحث, الساق الروبوتية البشرية التي يمكن ان تمثل رياضيا بو تم تصميم المسيطر الضبابي العصبي الهجين البسيط لتحسين اداء هذا الروبوت. هذا المسيطر يتكون من المسيطر ومع درجة واحدة من الحرية قد تم تحليله عقدة يذnid) ف مع المسيطر العصبي المشتق التكاملي () مع تسع قواعد تضاsisoاحادي االخراج (-احادي االدخال fdp)الضبابي النسبي المشتق ( نتائج المحاكاة بالماتالب لنموذج الساق الروبوتية مع المسيطر المقترح وضح كفاءة هذا المسيطر عند مقارنته مع نتائج ان واحدة مع دالة غير خطية. pi+2d, .pd+nid, fpd-id.المسيطرات سندس حسين al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 8, no.3, pp 74 89 (2012) experimental study on the impact of external geometrical shape on free and forced convection time dependent average heat transfer coefficient during cooling process sundus hussein abd department of mechanical engineering/ university of technology email: sundus.huseein@yahoo.com (received 20 december 2011; accepted 11 march 2012) abstract in this research, an experimental study was conducted to high light the impact of the exterior shape of a cylindrical body on the forced and free convection heat transfer coefficients when the body is hold in the entrance of an air duct. the impact of changing the body location within the air duct and the air speed are also demonstrated. the cylinders were manufactured with circular, triangular and square sections of copper for its high thermal conductivity with appropriate dimensions, while maintaining the surface area of all shapes to be the same. each cylinder was heated to a certain temperature and put inside the duct at certain locations. the temperature of the cylinder was then monitored. the heat transfer coefficient were then calculated for forced convection for several reynolds number (4555-18222).the study covered free convection impact for values of rayleigh number ranging between (1069-3321). imperical relationships were obtained for all cases of forced and free convection and compared with equations of circular cylindrical shapes found in literature. these imperical equations were found to be in good comparison with that of other sources. keywords: heat transfer, free convection, force convection, circular cylinder, square cylinder, triangular cylinder. 1. introduction heat transfer to and from a bank of tubes in cross flow is relevant to numerous heat exchanger applications, such as steam generator in a boiler or air cooling in the coil of an air conditioner in these applications, one fluid moves over the tubes, while a second fluid at a different temperature passes through the tubes and hence, heat is exchanged between the fluids based on the convection heat transfer coefficient. the tube rows of the bank are either arranged in staggered or aligned configuration in the direction of flow. the flow conditions within the bank are dominated by boundary layer separation effects and by wake interactions, which in turn influence the convection heat transfer. hence, the heat transfer coefficient associated with a tube is determined by its configuration and position of the bank. the heat transfer coefficient of a tube with staggered configuration is higher than that associated with the aligned one. the modeling of these relationships has been the concern of many researchers. generally, the average heat transfer coefficient for the entire tube bank is evaluated empirically based on the maximum fluid velocity. different forms of empirical correlations were proposed for air flow across tube bank with different geometry and configurations the applicability of these empirical models is limited to a confined range of flow conditions due to the complexity of the relationships. in this sense, therefore, artificial neural networks (anns) were applied in modeling heat transfer phenomena of different heat exchanger applications because of providing better and more reasonable solutions (islamoglu, 2003)[1]. jambunathan et al. (1996), [2] applied neural network model for prediction of convective heat transfer. more recently, varshney and panigrahi (2005) [3] developed a neural network mailto:sundus.huseein@yahoo.com sundus hussein abd al-khwarizmi engineering journal, vol. 8, no.4, pp 7489 (2012) 75 based control for a heat exchanger in a closed flow air circuit. fatona (2008) [4] studied the application of artificial neural network (ann) in modeling the heat transfer coefficient of a staggered multi-row, multi-column, cross-flow, tube-type heat exchanger. heat transfer data were obtained experimentally for air flowing over a bank of copper tubes arranged in staggered configuration with 5 rows and 4 columns. the reynolds number and the row number were used as input parameters, while the nusselt number was used as output parameter in training and testing of the multi-layered, feed-forward, backpropagation neural networks. the results show that the anns model were developed for the prediction of the convection heat transfer coefficient of air flowing over a staggered, multirow, multi-column, cross-flow, copper tube-type heat exchanger. the model has high prediction performance with mean relative error (mre) less than 1% for the training data set and less than 4% for the testing data sets respectively. the anns model can therefore be used as a modeling tool for preliminary design of heat exchangers. dhiman and chhabra (2007) [5] studied the effects of cross-buoyancy and of prandtl number on the flow and heat transfer characteristics of an isothermal square cylinder confined in channel .the numerical results have been presented for a range of conditions as: 1≤re≤30, 0.7≤pr≤100 (the maximum value of peclet number being 3000) and 0≤ri≤1for a fixed blockage ratio of 0.125.the drag coefficient is found to be less sensitive to the richardson number than the lift coefficient. the combined forced and free convection heat transfer from circular, square or triangular shapes has numerous industrial applications such as cooling tower, oil and gas pipelines, tubular and compact heat exchangers, cooling of electronic components, and flow dividers in polymer processing applications and so on. hashemian m. rahnama (2008) [6] studied the turbulent heat transfer, in a three dimensional channel flow, in the presence of a square cylinder, was investigated numerically. the existence of a square cylinder in a channel, compared to a plain. one, changes the heat transfer rate from the walls of the channel. a large eddy simulation (les) of a turbulent flow was performed to simulate flow behavior in a channel for reynolds numbers in the range of 1000 to 15000. the results obtained for the nusselt number distribution along the wall of the channel, at re = 3000, followed those of experimental data with good accuracy. it was observed that the existence of a square cylinder makes the attached wall boundary layer separate, with a subsequent recirculation zone downstream of the cylinder. the nusselt number distribution along the wall of the channel shows an increase, with a relative maximum, slightly downstream of the reattachment point. heat transfer from the wall of the channel increases with increasing reynolds number. a correlation was obtained for the variation of the mean total nusselt number with the reynolds number. the present study is aimed at high leisters the effect of the external shape of a cylindrical body on the convection heat transfer coefficient when the body is subjected to free or forced convection heat transfer by cross flow air stream. the body locations can also vary inside the air duct to determine its effect on the heat transfer rates. 2. experimentation the cross-flow heat exchanger apparatus (model te.93/a, plaint engineers, england) was used for the purpose of data gathering. the experimental setup is shown in figure (1). air at ambient temperature (working fluid), driven by a centrifugal fan powered by a 1 hp electric motor at a constant speed of 2,500 rpm, is blown perpendicularly over a cylindrical copper bar. the air flow rate over the cylinder is regulated by a throttle valve attached to the discharge end of the centrifugal fan. the copper bar was manufactured in the form of a cylinder with three different cross sections, while maintaining the proven surface area constant the three cross section tested shapes were circular, triangular and square as shown in figure(2) . table (1) shows the form of cylinders with dimensions and properties. table 1, physical and geometrical data for the three tested cylinders. circular cylinder m= 0.0875 kg d= 10 mm cp= 380 j/kg k square cylinder m=0.7 kg l1= 7.8 mm cp= 380 j/kg k triangular cylinder m= 0.057 kg l2= 10.2 mm cp= 380 j/kg k sundus hussein abd al-khwarizmi engineering journal, vol. 8, no.4, pp 7489 (2012) 76 control panel 11 total head tube 6 electric motor 1 inclined manometer 12 test element 7 fan 2 watch timer 13 thermometer 8 throttle opening 3 air inlet 9 working section 4 digital thermometer 10 electric heater 5 fig. 1.the experimental setup. circular cylinder 3 1 2 11 13 5 10 7 4 6 8 1 2 9 sundus hussein abd al-khwarizmi engineering journal, vol. 8, no.4, pp 7489 (2012) 77 triangular cylinder square cylinder fig. 2. three cross section al tested shapes (i.e. circular, triangular and square) the copper cylinder is heated to a maximum of about 85c with an electric heater, a k-type; 0.2 mm diameter thermocouple was imbedded at the centre of the cylinder to measure the temperature of the cylinder. the thermocouple voltage output is wired to digital thermometer to measure temperature. the heated cylinder is then inserted into the spaces provided in the working section at different locations (y) is the vertical distance of working section, see figure (3). fig. 3. the different locations at the test duct. sundus hussein abd al-khwarizmi engineering journal, vol. 8, no.4, pp 7489 (2012) 78 at each columns position, the cooling rate of the cylinder as indicated by a thermocouple embedded at its centre was recorded at the rate of 1 data per second by digital multimeter for 4 different flow rates with throttle valve at ( 20, 40, 60 ,80%) openings. the air velocity over the tube bank was measured with a total head tube connected to an inclined water manometer. by measuring the time of cooling. the heat transfer coefficient of forced convection and the nusselt number are calculated. after that empirical relationships were found several free convection tests were also carried out and the empirical were forced. figure (4) show the position of thermocouple used to measure the temperature in the circular cylinder. fig. 4. the position of thermocouple used to measure the temperature in the circular cylinder. 3. theoretical analysis for forced convection the reynolds number (redh ) of air flow is determined using the following relation [7]. re =ρa u dh /μa …(1) dh= 4*a/p …(2) the prandtle number is determined using the equation: pr= μa *cpa /ka …(3) and determined (tfilm) tfilm= (ts+ta)/2 …(4) for the purpose of estimating the heat transfer coefficient, it is assumed that all heat lost from the cylinder is transferred to the air flowing past it. it is also assumed that temperature gradient within the cylinder thickness is negligible, so that the thermocouple embedded at the centre in the inner diameter gives a true indication of the effective surface temperature of the cylinder. the rate of heat loss from cylinder to air is given by [4]: q0 =h a1 (t-ta) …(5) in a period of time (dt) the temperature drop (dt) is given as: -q0dt =m cp dt …(6) combining equations (5) and (6) and eliminating q0 give the following: -dt/ (t-ta) = (h*a1/m*cp) dt …(7) integrating equation (8) gives: ln (t-ta) – ln (to-ta) = (-h*a1*t) /m*cp …(8) where: t0 = cylinder temperature at time (t) =0. the plot of ln (t-ta) against t yields a straight line of slope (m) as: m= (-h*a1) / (m*cp) …(9) digital thermo meter sundus hussein abd al-khwarizmi engineering journal, vol. 8, no.4, pp 7489 (2012) 79 from which the heat transfer coefficient (h) is calculated as: h= (-m*cp /a1)*m …(10) the fully developed nusselt number (nu) is evaluated by nu= (h*dh) /ka …(11) the experimental nusselt number is calculated as [8]: nu= c rem pr0.3 …(12) the values of the constants(c&m) can be obtained from the relationship between the graphs ln (nu/pr0.3) and (ln re). for free convection the empirical relationship for free convection may be determined from [8]: nu = c (ra) n …(13) where: ra is rayleigh number and is given by: ra=gr * pr the grashof number is given by: gr= (β*(ρa)2*g*∆t*(lc)3) / (μa)2 …(14) where: the (β) coefficient of volumetric expansion of air is calculated from the following relationship β = 1/tfilm …(15) natural convection heat transfer coefficients are typically very low compared to those for forced convection. therefore, radiation is usually disregarded in forced convection problems, but it must be considered in natural convection problems that involve gas. this is especially the case for surfaces with high emissivities. the total rate of heat transfer is determined by adding the convection and radiation components, q total =qconv+ qrad …(16) radiation heat transfer from a surface at temperature ts surrounded by surfaces at a temperature t1 (both in absolute temperature unit k) is determined from: q rad =ɛ σ as (ts 4_t4 1) …(17) qconv= h*as * (ts-t 1) …(18) hequevlant = q total /(as*(ts-t 1)) …(19) nu= ( hequevlant*lc)/ka …(20) where: lc is the characteristic length. it is determined using the following relation. lc= as/p …(21) sample of calculation: the nusselt number is calculated by taking the model of circular cylinder at y= 5.8 cm, the value of (h) is obtained h= (m*cp*m) /a1 h= (0.0875*380*0.00938)/0.003925 = 79.46 j/m2s k the nu= (h*dh) /ka = (79.46*0.01)/0.027 =29.43 this procedure is used for square and triangular cylinders for all cases. 4. result and discussion figure (1) shows the change in the nusselt number with reynolds number for circular cylinder. nusselt number increases with increasing reynolds number. the values of nusselt number increases with distance vertical to the section of the test (y) where the values of nusselt number when (y = 5.8 cm) are larger than those at (y = 0.5 cm). figure (2) shows the variation of nusselt number with reynolds number for triangular cylinder it can be seen that nusselt number increases as reynolds number increases and also as (y) increases. a similar effect can be seen in figure (3) for the square cylinder. however the reason of this is the separation of flow behind these bodies which increases the heat transfer due to the mixing effect inside the generated vortices and turbulent boundary layer development. figure (4) shows the effect of changing the face of the triangular cylinder on flow and heat transfer coefficient and thus on the nusselt number. nusselt numbers around the perimeter of the cylinders are observed to decrease at the beginning up to the separation points and then increase in the transition regime up to the turbulent limit where they decrease again [9]. overall nusselt numbers are correlated with the reynolds numbers for the two positions of the cylinders in cross flow using the side length of the triangular cylinders .on the other hand, the overall nusselt numbers are correlated with reynolds number when the length of the cylinders is used as a characteristic length comparisons with circular and square cylinders in cross flow of air show that using triangular cylinder enhances the heat transfer at large reynolds number. sundus hussein abd al-khwarizmi engineering journal, vol. 8, no.4, pp 7489 (2012) 80 figure (5) shows the effect of changing the face of square cylinder on nusselt number, it can be seen that when the square cylinder is facing the flow with its vertex the nusselt number is large than the other cases where the flow hit the side of the square. it was observed that the existence of a square cylinder makes the attached wall boundary layer separate, with a subsequent recirculation zone downstream of the cylinder. the nusselt number distribution on the wall of the square cylinder shows an increase, with a relative maximum, slightly downstream of the reattachment point. heat transfer from the wall of the square cylinder increases with increasing reynolds number. a correlation was obtained for the variation of the mean total nusselt number with the reynolds number. figure (6) shows that the heat transfer coefficient from forced convection and thus the nusselt number of triangular cylinder is better than the cylinder of square and circular shape. this is due to flow separated behind the triangle shape is stronger than the other cylinder. as for free convection figure (7) shows the effect of face direction on nusselt number for square cylinder at free convection that the square cylinder (tilted angle450) has better heat transfer from the normally positioned square cylinder because the buoyancy forces generated by the base of 450 surface (♦ ) was found to have more effect than that of a horizontal surface (■) . figure (8) shows the impact of changing the face of the triangular cylinder on nusselt number for free convection. when the triangle cylinder faces down ward (▼) the heat transfer coefficient is better than the triangle cylinder that faces right (►) and faces up ward (▲) because of the buoyancy effect. a comparison between the three forms of the cylinder (circular, triangular and square) of free convection is given in figure (9). the heat transfer coefficient of the square cylinder is better than the that of triangular cylinder and circular cylinder. this may be attributed to the buoyancy forces developed by the heated surfaces of each of the three cylinders. the friction forces that retard the buoyancy forces are the smallest for the 45 tilted square cylinder. the relationship between the experimental nusselt number , reynolds number and prandtle number were obtained from drawing the relation between ln (nu/pr0.3) & (ln re) of forced convection as shown in figure (10) of the circular cylinder for reynolds numbers ranging (455518222) .the empirical relation obtained for nusselt number with reynolds number and prandtle number was as follows: nu = 0.247 re0.4381 pr0.3 at y= 0.5 cm nu = 0.2880 re0.5406 pr0.3 at y= 5.8 cm as well as for the case of the square cylinder in figure (11), the empirical relationships were: nu = 0.1346 re0.375 pr0.3 at y= 0.5 cm nu = 0.151 re0.5825 pr0.3 at y= 5.8 cm for the square cylinder (tilted angle of 450) in figure (12), the empirical relationships were as follow: nu = 0.275 re0.569 pr0.3 at y= 5.8 cm for the triangular cylinder the empirical relationship as shown in figure (13) & (14) is: nu =0.4168 re0.6748 pr0.3 at y=5.8 cm(▲) nu = 0.472 re0.587 pr0.3 at y= 5.8 cm (►) these relations were found to be in good comparison with other researchers such as those given by zukauskas and jakob [11] whose equations are: for circular cylinder (4000-40000) re nu = 0.1945 re0.592 pr0.3 for square cylinder (4000-40000) re nu = 0.102 re0.6٦٨ pr0.3 for square cylinder (tilted angle450) (4000-40000) re nu = 0.246 re0.588 pr0.3 it was found that the concordance between the equations derived from this research and the equations obtained from the source is as shown in table (2): table 2, type of cylinder nu present case nu zukauskas and jakob [11] difference % circular cylinder 33.174 35.532 6.6 % square cylinder 34.885 36.854 5.3 % square cylinder (tilted angle450) 55.866 59.8 6.5 % sundus hussein abd al-khwarizmi engineering journal, vol. 8, no.4, pp 7489 (2012) 81 figures (15-17) show the variation of surface temperature of the cylinder with time for circular, triangular and square cylinders, respectively. the higher reynolds number is the less time is required to lower the temperature of the surface of the cylinder due to the speed increase of air flowing, so more heat is removed from the specimen. fig. 1. nusselt number variation with reynolds number for circular cylinder of forced convection case. fig. 2. nusselt number variation with reynolds number for triangular cylinder of forced convection case. 0 10 20 30 40 50 60 70 0 5000 10000 15000 20000 n u re y= 0.5 cm y= 5.8 cm 0 5 10 15 20 25 30 35 40 45 50 55 0 4000 8000 12000 16000 20000 n u re y=0.5 cm y=5.8 cm sundus hussein abd al-khwarizmi engineering journal, vol. 8, no.4, pp 7489 (2012) 82 fig. 3. variation nusselt number with reynolds number of square cylinder of forced convection. fig. 4. the impact of changing the form of the cylinder on a number of the cylinder nusselt triangular forced convection. fig. 5. the impact of changing the face of square cylinder on nusselt number for forced convection. 0 10 20 30 40 50 60 0 5000 10000 15000 20000 n u re y= 0.5 cm y= 5.8 cm 0 10 20 30 40 50 60 0 5000 10000 15000 20000 n u re y= 5.8 cm 1 2 3 4 0 10 20 30 40 50 60 70 0 5000 10000 15000 20000 n u re y= 5.8 cm 0 0 sundus hussein abd al-khwarizmi engineering journal, vol. 8, no.4, pp 7489 (2012) 83 fig. 6. the impact of changing the face of cylinder on nusselt number for forced convection at y = (5.8 cm). fig. 7. the impact of changing the face of the square cylinder on nusselt number for free convection at (y= 5.8 cm). fig. 8. the impact of changing the face on nusselt number for triangular cylinder at free convection at (y= 5.8 cm). 0 10 20 30 40 50 60 70 0 5000 10000 15000 20000 n u re circular bar tringulare bar square bar 2 3 4 5 6 7 8 0 500 1000 1500 2000 2500 3000 n u ra 0 0 0 1 2 3 4 5 6 0 500 1000 1500 2000 2500 3000 n u ra y= 5.8 cm 0 0 0 ► ▲ ▼ sundus hussein abd al-khwarizmi engineering journal, vol. 8, no.4, pp 7489 (2012) 84 fig. 9. the impact of changing the face of cylinder on nusselt number for free convection at y = (5.8 cm). fig. 10. the empirical relationship between the (ln re) and (ln nu/pr0.3) of forced convection upon circular cylinder (y= 5.8 cm). fig. 11. the empirical relationship between the (ln re) and (ln nu/pr0.3) of forced convection upon square cylinder (y= 5.8 cm). 1 2 3 4 5 6 7 0 500 1000 1500 2000 2500 3000 n u ra circular bar triangular bar square bar -1 -0.75 -0.5 -0.25 0 0.25 0.5 0.75 1 1.25 1.5 1.75 2 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 ln (n u/ pr 0. 3 ) ln re -1.5 -1.25 -1 -0.75 -0.5 -0.25 0 0.25 0.5 0.75 1 1.25 1.5 1.75 2 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5ln (n u/ pr 0. 3 ) lnre sundus hussein abd al-khwarizmi engineering journal, vol. 8, no.4, pp 7489 (2012) 85 fig. 12. the empirical relationship between the (ln re) and (ln nu/pr0.3) of forced convection upon square cylinder (y= 5.8 cm). fig. 13. the empirical relationship between the (ln re) and (ln nu/pr0.3) of forced convection upon triangular cylinder (y= 5.8 cm). fig. 14. the empirical relationship between the (ln re) and (ln nu/pr0.3) of forced convection upon triangular cylinder (y= 5.8 cm). -0.5 -0.25 0 0.25 0.5 0.75 1 1.25 1.5 1.75 2 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 ln (n u/ pr 0. 3 ) ln re -0.5 -0.25 0 0.25 0.5 0.75 1 1.25 1.5 1.75 2 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 ln (n u/ pr 0. 3 ) ln re -1 -0.75 -0.5 -0.25 0 0.25 0.5 0.75 1 1.25 1.5 1.75 2 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 ln (n u/ pr 0. 3 ) ln(re) sundus hussein abd al-khwarizmi engineering journal, vol. 8, no.4, pp 7489 (2012) 86 fig. 15. the impact of changing reynolds number on time for circular cylinder at(y = 5.8cm)) of forced convection. fig. 16. the impact of changing the reynolds number on the time of low temperature triangular cylinder at(y = 5.8cm)) of forced convection. fig. 17. the impact of changing the reynolds number on the time of low temperature square cylinder at(y = 5.8cm) of forced convection. 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 0 25 50 75 100 125 150 175 200 225 250 l n( ts -t a) t(sec) y= 5.8 cm re=4555 re=7890 re=13666 re=18222 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 0 25 50 75 100 125 150 175 200 225 250 l n( ts -t a) t(sec) y= 5.8 cm re=4555 re=7890 re=13666 re=18222 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 0 25 50 75 100 125 150 175 200 225 250 l n( ts -t a) t(sec) y=5.8 cm re=4555 re=7890 re=13666 re=18222 sundus hussein abd al-khwarizmi engineering journal, vol. 8, no.4, pp 7489 (2012) 87 5. conclusion experimental study was made on free and forced heat transfer from three cylinders of different cross-sections circular, triangular and square in cross flow of air. the three cylinders were manufactured from copper for its high conductivity. the three cylinders were made to have equal surface area to compare the effect of their shape on heat transfer coefficient. it was found that in the case of forced convection, the heat transfer of the triangular cylinder is better than that of the square and circular cylinder. for the triangular cylinder it was found ,the best case of heat transfer was when the triangle cylinder faces right (►) .the square cylinder (tilted angle450) has better heat transfer than the square cylinder has when it lies on one of its width. in the case of free convection the best position of the triangular cylinder was found where the triangle cylinder faced down ward (▼) .several empirical relationships were obtained for the case of forced convection, for all cylindrical shapes, as well as for free convection. these relations were found to be in good comparison with those of others such as those of zukauskas and jakob [11] . list of symbols unit meaning of the symbol symbol m2 effective surface area of cylinder a1 m2 the surface area of heat transfer as m2 the cross section area a j/kg k specific heat of copper cylinder cp j/kg k specific heat of the air cpa m is the hydraulic diameter dh m outside diameter of circular cylinder d j/m2s k coefficient of heat transfer h m head tube connected to an inclined water manometer hw j/ms k thermal conductivity of air ka m side length of square cylinder l1 m side length of triangular cylinder l2 kg mass of cylinder m m perimeter of duct p j/s rate of heat loss q0 k temperature of cylinder t k temperature of air ta k surrounded temperature t1 m/sec mean velocity of air u list of greek letters unit meaning of the greek letters greek letters kg/m3 density of air ρa kg/m3 density of water ρw kg/ms viscosity of air μa is the emissivity of the surface w/m2 .k4 is the stefan–boltzmann constant=5.67 *10-8 σ 6. references [1] islamoglu, y. 2003. “a new approach for the prediction of the heat transfer rate of the wire-on-tube type heat exchanger–– use of an artificial neural network model”. applied thermal engineering. 23:243-249. [2] jambunathan, k., s.l. hartle, s. ashforthfrost, v.n. fontama. 1996. “evaluating convective heat transfer coefficients using neural networks”. international journal of heat and mass transfer. 39(11): 2329-2332. [3] varshney, k. and p.k. panigrahi. 2005. “artificial neural network control of a heat exchanger in a closed flow air circuit”. applied soft computing. 5:441-465. [4] fatona, m.sc." artificial neural network modeling of heat transfer in a staggered cross-flow tube-type heat exchanger". the pacific journal of science and technology volume 9. number 2. november 2008 (fall). [5] dhiman and chhabra 2008 "steady mixed convection across confined square cylinder "international communications in heat and mass transfer 35(2008)47-55. [6] s.m. hashemian and m. rahnama 2008"turbulent heat transfer in a channel with a built-in square cylinder: the effect of reynolds number" scientia iranica, vol. 15, no. 1, pp 57-64. [7] j.p. holman .book "heat transfer (sixth edition). sundus hussein abd al-khwarizmi engineering journal, vol. 8, no.4, pp 7489 (2012) 88 [8] joan i. pop, derek b. ingham, book (2001)" convective heat transfer": mathematical and computational modeling of viscous fluids and porous media. [9] mohamed ali*,(2011)" forced convection heat transfer over horizontal triangular cylinder in cross flow" international journal of thermal sciences 50 (2011) 106-114. [10] yunus a.cengel.book "heat transfer by cengel 2nd edition (2002). [11] zukauskas and jakob. book "external forced convection" cen58933_ch07.qxd 9/4/2002. )2012( 7489، صفحة 4، العدد8مجلة الخوارزمي الھندسیة المجلد سندس حسین عبد 89 حرارة لمعامل انتقالدراسة عملیة لتاثیر تغییر الشكل الخارجي للجسم على المعدل الزمني للحمل الحر والقصري خالل عملیة التبرید سندس حسین عبد الجامعة التكنولوجیة/ قسم الھندسة المیكانیكیة sundus.huseein@yahoo.com: البرید االلكتروني الخالصة الشكل الخارجي لجسم اسطواني على معامل انتقال الحرارة الناتج عن الحمل القسري والحمل الحر عند تم في ھذا البحث اجراء دراسة عملیة عن تأثیر لحمل القسري وضع ھذا الجسم داخل مجرى ھوائي وكذلك لبیان تاثیر تغیر موقع الجسم داخل مجرى الھواء وسرعة الھواء على قیم معامل انتقال الحرارة با من معدن النحاس لموصلیتھ الحراریة العالیة بابعاد ) دائریة ومثلثة و مربعة المقطع (حیث تم تصنیع اسطوانات . خارجي والحمل الحر مع تغیر الشكل ال ومراقبة مناسبة مع المحافظة على ثبوت المساحة السطحیة لجمیع االشكال وتسخینھا الى درجة حرارة معینة ووضعھا داخل مجرى الھواء بمواقع محددة وبیان تاثیر تغیر ) ٤٥٥٥-١٨٢٢٢(حرارة االسطوانة وتم حساب معامل انتقال الحرارة بالحمل القسري لقیم عدد رینولدز تتراوح بین انخفاض درجة ن لي تتراوح بیالسرعة غلى معامل انتقال الحرارة بالحمل القسري واجریت كذلك دراسة الحمل الحر وبیان تاثیره غلى معامل انتقال الحرارة لقیم عدد رای وتم الحصول على عالقة تجریبیة في حالة الحمل القسري لجمیع اشكال االسطوانة وتم مقارنتھا مغ المعادالت التجریبیة ). 1069.320-3321.682( .المصادر االخرىالموجودة في مصادر االشكال االسطوانیة الدائریة وكانت قیم الثوابت مقاربة بشكل جید للقیم الموجودة في المعادالت التجریبیة في mailto:sundus.huseein@yahoo.com اسامة وماجد al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 8, no.4, pp 53 -61(2012) evaluation study of glass fiber reinforced polyester and kevlar reinforced polyester by taguchi method osama sultan m.* majid hmeed a. ishraq abdul razaq k. department of materials engineering/university of technology * email: oalaamiri@yahoo.com (received 27 december 2011; accepted 6 september 2012) abstract in the present investigation two different types of fiber reinforced polymer composites were prepared by hand lay-up method using three different parameters (curing temperature, pressing load and fiber volume fraction). these composites were prepared from the polyester resin as the matrix material reinforced with glass fibers as first group of samples and mat kevlar fibers as the second group, both with different volume fractions (4%, 8%, and 12%) of fibers. they were then tested by tensile strength and impact strength. the main objective in this study is to use taguchi method for predicting the better parameters that give the better tensile and impact strength to the composites, and then preparing composites at these parameters and comparing them with the randomly used once. the experimental and analytical results showed that the taguchi method was successful in optimizing the parameters that give the highest properties and it can find the most influential parameter regardless of the material used. also it showed that the volume fraction was the most influential parameter on the tensile and impact strength. the difference between these composites was in the properties values and that the kevlar composites have higher tensile and impact strength. keywords: fiber reinforced composites, taguchi method, tensile strength, impact strength. 1. introduction composite material is well known as an excellent structural material. it consists of two or more materials (i.e. fiber and matrix) combined to give superior performance compared to the properties of the individual components. fiber reinforced plastic composites using resin such as epoxy, polyester and vinylester are extensively used as structural materials for many applications such as automotive industry, aerospace and civil engineering structures due to their high specific stiffness, strength, and cost and weight advantages. manufacturing of structural materials made from fiber composites calls for an improved strength to weight ratio [1,2, 3]. glass-fiber-reinforced polymers (grps) have received considerable attention as alternatives to steel and aluminum as structural materials; on the other hand, kevlar fibers as reinforcement became more popular in specific applications such as parachute webbing, rocket motor casings, jetengine containment, aircraft seats, and automobile tires due to their improved stiffness and density properties in relative to glass and their considerably lower cost than that of boron or even graphite fibers [4, 5]. the quality of any composite material is influenced by varying processing parameters. among these parameters, there must be one or two that have the most influence. it has been realized that the full economic and technical potential of any manufacturing process can be achieved only while the process is run with the optimum parameters. one of the most important optimization processes is taguchi method [6]. this technique helps to study effect of many factors (variables) on the desired quality characteristic most economically. by studying the effect of individual factors on the results, the best factor combination can be determined. taguchi designs experiments using specially constructed tables known as “orthogonal array” (oa). the use of these tables makes the design of experiments mailto:oalaamiri@yahoo.com osama sultan m. al-khwarizmi engineering journal, vol. 8, no.4, pp 5361 (2012) 54 very easy and consistent and it requires relatively lesser number of experimental trials to study the entire parameter space. as a result, time, cost, and labour saving can be achieved. the experimental results are then transformed into a signal-to-noise (s/n) ratio. taguchi technique recommends the use of the s/n ratio to measure the quality characteristics deviating from the desired values. usually, there are three categories of quality characteristic in the analysis of the s/n ratio, i.e. the-lower-the-better, the-higher-the-better, and the nominal-the-better. the s/n ratio for each level of process parameters is computed based on the s/n analysis. regardless of the category of the quality characteristic, a greater s/n ratio corresponds to better quality characteristics. therefore, the optimal level of the process parameters is the level with the greatest s/n ratio. furthermore, a statistical analysis of variance (anova) can be performed to analyze which process parameters are statistically significant. with the s/n and anova analyses, the optimal combination of the process parameters can be predicted. finally, a confirmation experiment may be needed to verify the optimal process parameters obtained from the parameter design [7,8]. taguchi method provides a simple efficient and systematic approach to optimize design for performance, quality and cost. the methodology is valuable when design parameters are qualitative and discrete. taguchi parameter design can optimize the performance characteristic through the setting of design parameters and reduce the sensitivity of the system performance to source variation [9,10]. the taguchi approach reduces the experimental trials to a minimum number and it is a multi – step process which follow a certain sequence for the experiments to yield an improved understanding of product or process performance [11]. 2. materials and methods in this study, general purpose unsaturated polyester resin is used as the matrix and two types of reinforcing fibers (i.e. glass fibers and kevlar fibers). table (1) shows the mechanical properties of these materials. two types of composites were prepared by the hand lay-up method (i.e. glass fiber reinforce polyester gfrp and kevlar reinforced polyester kfrp). at first a glass mold of the dimensions (30*30*5 cm) was used with clean and regular inner surfaces, and then the resin was mixed with 2% methyl-ethyl-ketone peroxide (mekp) as a hardener. after a short time, the mixture became as a gel which is then poured into the mold. the fibers in a mat shape were put between two layers of the matrix. the layered structure was put under different loads for about 24 hours for proper curing at room temperature and allowed to harden on cure. it was cured at room temperature for 24 hours and followed by oven cure at different temperatures so that the matrix completely seeps in and become dry. three volume fractions (4%, 8% and 12%) of reinforcements were used for each type of composites. the resulted composites were then cut into appropriate specimens for the tensile and impact tests. after some preliminary tests, the experimental conditions shown in table (2) were chosen to study the effects of processing parameters (curing temperature, pressing load and volume fraction) on the tensile and impact strength of the composites. table 1, general properties of the used materials. property u-polyester e-glass fibers kevlar fibers (49) tensile strength (mpa) 40-90 1500 2800 modulus of elasticity (gpa) 24.5 76 125 density (gm/cm3) 1.2-1.5 2.59 1.44 elongation (%) 2 3.8 2.1 linear coefficient of thermal expansion (*10-6 k-1) 75 5 -2 osama sultan m. al-khwarizmi engineering journal, vol. 8, no.4, pp 5361 (2012) 55 table 2, control factors and their levels. factor control factor level 1 level 2 level 3 a curing temperature (ºc) 20 40 60 b pressing load (gm) 100 150 200 c volume fraction (%) 4 8 12 3. application of taguchi method the taguchi method of design of experiments is a statistical tool based on the systematic approach of conducting minimal number of experiments using a mathematical instrument called orthogonal arrays. traditionally, the method has been used to predict the significance of contribution of each design variables and their level to achieve optimum combination by conducting a real time experiment. in our work, an orthogonal array of the type (l9 33) was chosen since we have three factors (variables) and three levels. table (3) represents the standard orthogonal array of type (l9 33). during the composites preparation method, three process parameters for each type of composites were considered. these are: (1) curing temperature; (2) pressing load, and (3) fibers volume fraction. each is at three levels as listed in table (2). the degree of freedom for three parameters in each of the three levels is calculated as follows [6]: degree of freedom (dof) = number of levels -1 …(1) for each factor, dof equals to: for (a); dof = 3 – 1 = 2 for (b); dof = 3 – 1 = 2 for (c); dof = 3 – 1 = 2 table 3, the standard (l9 33) orthogonal array [9]. experiment number p1 p2 p3 1 1 1 1 2 1 2 2 3 1 3 3 4 2 1 3 5 2 2 1 6 2 3 2 7 3 1 2 8 3 2 3 9 3 3 1 * (p) represents factors. in this research nine experimental trails were conducted at different parameters, for each type of composites and they were cut and tested by tensile and impact tests. figure (1) shows some of the specimens. the tensile tests were performed by using the time testing machine according to (astm d63887) standard in which the gage length is (60mm). the impact tests were performed by time testing machine (izod) type xju-22 according to (d25687) standard with the dimensions (55 * 10 * 4mm). tables (4) and (5) indicate the used parameters and the result values of tensile and impact strength for (gfrp) and (kfrp) respectively. a standard three level (l9 33) orthogonal array with nine experimental runs was selected. the total degree of freedom is calculated from the following [6]: total dof = no. of experiments – 1 …(2) the total dof for the experiments is: total dof = 9 – 1 = 8 osama sultan m. al-khwarizmi engineering journal, vol. 8, no.4, pp 5361 (2012) 56 fig. 1. some of the prepared specimens (upper: gfrp, lower: kfrp). table 4, experimental runs of the oa (l9 33) for the gfrp. experiment number control factor response factor a b c tensile strength (mpa) impact strength (mpa) 1 20 100 4 56 49.7 2 20 150 8 62 61.9 3 20 200 12 78 76.4 4 40 100 12 74 71.4 5 40 150 4 58 53.3 6 40 200 8 65 63.2 7 60 100 8 69 67.1 8 60 150 12 91 78.4 9 60 200 4 60 56.1 gfrp: glass fiber reinforced polyester. a: curing temperature (ºc); b: pressing load (gm); c: volume fraction (%) and e: error. table 5, experimental runs of the oa (l9 33) for the kfrp. experiment number control factor response factor a b c tensile strength (mpa) impact strength (mpa) 1 20 100 4 59 68.6 2 20 150 8 81 87.4 3 20 200 12 107 101.4 4 40 100 12 101 98.7 5 40 150 4 64 70.5 6 40 200 8 92 89.8 7 60 100 8 93 90.2 8 60 150 12 119 105.1 9 60 200 4 77 73.9 kfrp: kevlar fiber reinforced polyester. osama sultan m. al-khwarizmi engineering journal, vol. 8, no.4, pp 5361 (2012) 57 taguchi method stresses the importance of studying the response variation using the signal – to – noise (s/n) ratio, resulting in minimization of quality characteristic variation due to uncontrollable parameter. since the tensile and impact strength were required to be high, the concept of "the larger the better" is considered. the s/n ratio used for this type of response is given by [6]: …(3) where i: experiment number. u: trail number. ni: number of trails for experiment i. yu: the response (property) value for a trial condition repeated (u) times. the composite preparation parameters, namely: (a) curing temperature, (b) pressing load and (c) particles volume fraction were assigned to the 1st , 2nd and 3rd column of the (l9 34) array, respectively. the 4th column was assigned as error (e). the s/n ratios were computed for tensile strength and impact strength in each of the nine trial conditions for each type of composites and their values are given in tables (6) and (7). computation scheme of pareto anova (analysis of variance) for three level factors is shown in table (8). in order to study the contribution ratio of the process parameters, pareto anova was performed for tensile and impact strengths. the details are given in tables (9) and (10) respectively for the gfrp and tables (11) and (12) for the kfrp. table 6, s/n ratio of tensile and impact strengths for the gfrp. experiment number a b c e s/n ratio (tensile strength) s/n ratio (impact strength) 1 1 1 1 1 34.96 33.93 2 1 2 2 2 35.85 35.83 3 1 3 3 3 37.84 37.66 4 2 1 3 2 37.38 37.07 5 2 2 1 3 35.27 34.53 6 2 3 2 1 36.26 36.01 7 3 1 2 3 36.78 36.53 8 3 2 3 1 39.19 37.89 9 3 3 1 2 35.56 34.98 table 7, s/n ratio of tensile and impact strengths for the kfrp. experiment number a b c e s/n ratio (tensile strength) s/n ratio (impact strength) 1 1 1 1 1 35.42 36.73 2 1 2 2 2 38.17 38.83 3 1 3 3 3 40.59 40.12 4 2 1 3 2 40.09 39.89 5 2 2 1 3 36.12 36.96 6 2 3 2 1 39.28 39.07 7 3 1 2 3 39.37 39.1 8 3 2 3 1 41.51 40.43 9 3 3 1 2 37.73 37.37 osama sultan m. al-khwarizmi engineering journal, vol. 8, no.4, pp 5361 (2012) 58 table 8, pareto anova for three level factors [6]. factors a b c e total sum. at factor level a1 b1 c1 e1 t a2 b2 c2 e2 a3 b3 c3 e3 sum. of squares of differences sa sb sc se st degree of freedom (contribution ratio)/100 sa/ st sb/ st sc/ st se/ st 1 t = a1 + a2 + a3 sa = ( a1 a2)2 + ( a1 a3)2 + ( a2 a3)2 sb = ( b1 b2)2 + ( b1 b3)2 + ( b2 b3)2 sc = ( c1 c2)2 + ( c1 c3)2 + ( c2 c3)2 se = ( e1 e2)2 + ( e1 e3)2 + ( e2 e3)2 st = sa + sb + sc + se table 9, pareto anova of tensile strength for the gfrp. factors a b c e total sum. at factor level 108.65 109.12 105.79 110.41 329.09 108.91 110.31 108.89 108.79 111.53 109.66 114.41 109.89 sum. of squares of differences 15.226 2.13 114.385 4.105 135.846 degree of freedom 2 2 2 2 8 (contribution ratio)/100 11.208 1.568 84.202 3.022 1 optimum level 2 a3 60 3 b2 150 1 c3 12 table 10, pareto anova of impact strength for the gfrp. factors a b c e total sum. at factor level 107.42 107.53 103.44 107.83 324.43 107.61 108.25 108.37 107.88 109.4 108.65 112.62 108.72 sum. of squares of differences 7.161 1.933 126.64 1.5 137.234 degree of freedom 2 2 2 2 8 (contribution ratio)/100 5.218 1.409 92.28 1.093 1 optimum level 2 a3 60 3 b3 200 1 c3 12 osama sultan m. al-khwarizmi engineering journal, vol. 8, no.4, pp 5361 (2012) 59 table 11, pareto anova of tensile strength for the kfrp. factors a b c e total sum. at factor level 114.18 114.88 109.27 116.21 348.28 115.49 115.8 116.82 115.99 118.61 117.6 122.19 116.08 sum. of squares of differences 31.075 11.485 252.766 0.0734 295.4 degree of freedom 2 2 2 2 8 (contribution ratio)/100 10.52 3.888 85.567 0.025 1 optimum level 2 a3 60 3 b3 200 1 c3 12 table 12, pareto anova of impact strength for the kfrp. factors a b c e total sum. at factor level 115.68 115.72 111.06 116.23 348.5 115.92 116.22 117 116.09 116.9 116.56 120.44 116.18 sum. of squares of differences 2.506 1.071 135.102 0.03 138.71 degree of freedom 2 2 2 2 8 (contribution ratio)/100 1.81 0.77 97.4 0.02 1 optimum level 2 a3 60 3 b3 200 1 c3 12 4. results and discussion tables (4) and (5) represents the values of tensile and impact strengths for both types of composites and it shows that kevlar composites gave higher tensile and impact than the glass fiber composites. this is true since the kevlar fibers have more toughness. from table (9), it can be seen that the third level of factor (a) give the highest summation (i.e. a3, which is 60ºc curing temperature). the highest summation for factor (b) is at the second level (i.e. b2, which is 150 gm) and the highest summation for factor (c) is at the third level (i.e. c3, which is 12% volume fraction). these predicted parameters are already used in the gfrp composite preparation as indicated in table (4). it can be seen from table (10) for the impact results of gfrp that the optimum levels were a3, b3 and c3 (i.e. 60ºc, 200 gm and 12%). these parameters were not used in the composite trails as indicated in table (4). an experiment was conducted at the predicted parameters (a = 60ºc, b = 200 gm, and c = 12 % volume fraction), and the resulted specimen was tested by impact. the resulted impact strength was (82 mpa) which is greater than the impact strength values in table (4). the optimum levels of kevlar composites parameters for the tensile and impact strengths are similar to the results of impact of the glass fiber composites in which a3, b3 and c3 (i.e. 60ºc, 200 gm and 12%) had gave the highest contribution ratio. these parameters were also not used in the composite trails as indicated in table (5). two additional specimens of kevlar fiber reinforced polyester were prepared at the predicted parameters (a = 60ºc, b = 200 gm, and c = 12 % volume fraction), and were tested by tensile and osama sultan m. al-khwarizmi engineering journal, vol. 8, no.4, pp 5361 (2012) 60 impact. the resulted tensile strength was (121 mpa) while the impact strength was (109 mpa) which are greater than the strength values in table (5). these results proved the success of taguchi method in the prediction of the optimum parameters for higher tensile and impact strengths. in tables (9, 10, 11 and 12), it was found that the fiber volume fraction contributes a larger impact on tensile and impact strength of the composites followed by curing temperature and then finally pressing load. 5. conclusions in this research taguchi's off – line quality control method was applied to determine the optimal process parameters by which a glass fiber reinforced polyester and kevlar fiber reinforced polyester were prepared. for this purpose, concepts like orthogonal array, s/n ratio and anova were employed. after determining the optimum process parameters, a confirmation experiments were conducted. in light of our analysis the following conclusions were drawn: 1. the optimum level of process parameters to obtain good tensile and impact strengths for the composites prepared by the hand lay-up method are 12% volume fraction of fibers, 60ºc curing temperature, and 150 gm pressing load for tensile strength and 200 gm for impact strength for the glass fiber reinforced polyester. while it is 12% volume fraction of fibers, 60ºc curing temperature, and 200 gm for tensile and impact strengths for the kevlar fiber reinforced polyester. 2. taguchi method was successful in predicting the parameters that give the highest properties and it can find the most influential parameter regardless of the material used. 3. from the pareto analysis it was evident that the volume fraction is a major contributing factor for improving tensile and impact strengths. 4. taguchi method proved its success in predicting the optimum parameters to reach the best properties. 6. references [1] zulkifli r., "surface fracture analysis of glass fiber reinforced epoxy composites treated with different type of coupling agent", european journal of scientific research, vol.29, no.1, (2009), pp.55-65. [2] iwaya t. et. al., "recycling of fiber reinforced plastics using depolymerization by solvothermal reaction with catalyst", j mat. sci., vol.43, (2008), pp.2452–2456. [3] kang g. et. al., "uniaxial ratchetting of polymer and polymer matrix composites: time-dependent experimental observations", mat. sci. eng. a, vol.523, (2009), pp.13–20. [4] bagherpour s. et. al., "effects of concentrated hcl on the mechanical properties of storage aged fiber glass polyester composite", materials and design, vol.30, (2009), pp.271–274. [5] wallace m. m., bert c. w., "experimental determination of dynamic young's modulus and damping of an aramid-fabric/polyester composite material", proc. okla. acad. sci., vol.59, (1979), pp.98-101. [6] muhammed o. s., saleh h. r., alwan h. l., "using of taguchi method to optimize the casting of al–si /al2o3 composites", eng. & tech. j., vol.27, no.6, (2009), pp. 1143 – 1150. [7] kamaruddin s., khan z. a., foong s. h., "application of taguchi method in the optimization of injection moulding parameters for manufacturing products from plastic blend", iacsit international journal of engineering and technology, vol.2, no.6, (2010), pp. 574 – 580. [8] mehravar r. et. al., "applying the taguchi method for optimized fabrication of lactalbumin nanoparticles as carrier in drug delivery and food science", iranica journal of energy & environment, vol.2, no.1, (2011), pp.87-91. [9] ross phillips j., "taguchi technique for quality engineering", new york: mcgraw – hill, (1988). [10] roy ranjit k., "a primer on taguchi method", new york: van nostrad reinhold, (1990). [11] basavarajappa s., chandramohan g., paulo davim j., "application of taguchi techniques to study dry sliding wear behaviour of metal matrix composites", materials and design, vol. 28, (2007), pp. 1393 – 1398. )2012( 5361، صفحة 4، العدد8مجلة الخوارزمي الھندسیة المجلد أسامة سلطان محمد 61 دراسة تقییم ما بین البولي استر المقوى بالیاف الزجاج والبولي استر المقوى بالیاف الكفلر بواسطة طریقة تاكوجي اشراق عبد الرزاق كاظم عبد المجید میدحماجد *أسامة سلطان محمد الجامعة التكنولوجیة /دقسم ھندسة الموا oalaamiri@yahoo.com : االلكتروني البرید* الخالصة درجة (ات ھي تم في ھذا البحث تحضیر مادتین متراكبتین مختلفتین من البولیمر المقوى بااللیاف بواسطة طریقة التحضیر الیدوي وباستخدام ثالثة متغیر كمجموعة ف الزجاج تم تحضیر المواد المتراكبة من راتنج البولي استر كمادة اساس مقوى بالیا). حرارة المعالجة، حمل الكبس و الكسر الحجمي لاللیاف تم بعدھا اجراء اختباري %). ١٢، %٨، %٤(اولى من العینات والیاف الكفلر كمجموعة ثانیة من العینات وبكسور حجمیة مختلفة لكل نوع من االلیاف ھي لمتغیرات التي تعطي افضل مقاومة ان الھدف االساسي من البحث ھو استخدام طریقة تاكوجي للتكھن بافضل ا. مقاومة الشد ومقاومة الصدمة على العینات اظھرت النتائج . شد وصدمة للمواد المتراكبة ومن ثم تحضیر مواد متراكبة عند ھذه المتغیرات ومقارنتھا مع المتغیرات المستخدمة المختارة عشوائیا الخواص وكذلك یمكنھا ایجاد المتغیر االكثر تاثیرا على التجریبیة والتحلیلیة بان طریقة تاكوجي كانت ناجحة في التكھن وایجاد المتغیرات التي تعطي اعلى كذلك ان الفرق . اظھرت النتائج كذلك بان الكسر الحجمي كان المتغیر االكثر تاثیرا على مقاومة الشد والصدمة. الخواص بغض النظر عن المادة المستخدمة .ت الیاف الكفلر اعطت مقاومة شد وصدمة اعلىبین المادتین المحضرتین كان في قیم الخواص وان المادة المتراكبة ذا mailto:oalaamiri@yahoo.com (microsoft word \323\332\317 \322\333\341\346\34177-89) al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 14, no. 1, march, (2018) p.p. 77-89 creating through points in linear function with parabolic blends path by optimization method saad zaghlul saeed al-khayyt department of mechatronics / college of engineering/ mosul university/ iraq email: alkhyaat@yahoo.com (received 8 may 2017; accepted 9 october 2017) https://doi.org/10.22153/kej.2018.10.005 abstract the linear segment with parabolic blend (lspb) trajectory deviates from the specified waypoints. it is restricted to that the acceleration must be sufficiently high. in this work, it is proposed to engage modified lspb trajectory with particle swarm optimization (pso) so as to create through points on the trajectory. the assumption of normal lspb method that parabolic part is centered in time around waypoints is replaced by proposed coefficients for calculating the time duration of the linear part. these coefficients are functions of velocities between through points. the velocities are obtained by pso so as to force the lspb trajectory passing exactly through the specified path points. also, relations for velocity correction and exact velocity solution are derived. simulation results show that the engagement of modified lspb trajectory with pso to work well on the tested cases. this proposed method is very simple which can be used for on-line path planning, and not necessarily to use high acceleration magnitude. keywords: adaptive inertia weight, linear segment with parabolic blend, particle swarm optimization, robot manipulator, through point, trajectory generation. 1. introduction straight line segments is the output from motion planners. this path has velocity discontinuity at waypoints. to achieve an efficient execution on the robot, blends are added to ensure a smooth transition between segments [1]. a common trajectory for industrial robots is the linear segment with parabolic blend (lspb) [2, 3]. the lspb needs only the initial and final joint angles, traveling time, and either angular acceleration or angular velocity. numerous methods and algorithms have been established which generate such trajectories with velocity, acceleration, and jerk limitations [4, 5]. in lspb, it is required to use high acceleration's magnitude to be quite close to the desired waypoint. time-optimal solution for time durations of lspb so as to satisfy the constraints velocity and acceleration is presented in [6]. this requires calculation a factor for velocity reduction of two neighboring linear segments in order to prevent overlapping of blend phases. yet, this ethomd can lead to very slow trajectories [7]. rymansaib et al. used a series of time-delayed third-order exponential function to generate an approximation to the trapezoidal velocity profile of lspb [8]. the motion duration is affected by high blending percentage as well as the corresponding accuracy at waypoints. a new technique "envelope of tangents planning" had been developed so as to generate trajectory that reaches waypoints in specified moments of time [9]. this is achieved by assigning positions and tangential velocities that the joints must have when the end-effector passes through each of those waypoints. additionally, the online trajectory generation algorithm was combined with the reflexxes libraries to make the trajectory reaches waypoint with continuous acceleration and jerk [10, 11]. saad zaghlul saeed al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 7789 (2018) 78 new path planning algorithm was developed for the control of an xy -motion stage using lspb and minimum time trajectory for an aerosol printing system [12]. the algorithm calculates blend times and constant velocity based on given trajectory conditions. but large error in speed appeared for acute angle trajectory. this problem can be considered as multi-segment trajectories without stopping at waypoints. weber et al. used the tool corde (corner drive with defined speed) to visualize the characteristic of the distance to the corner depending on the speed deviation for transition between path segments [13]. but the absolute maximum acceleration is difficult to obtain as a realistic value which is the sole characteristic value. this results in a loss on performance for many transition points. classic optimization approaches suffer from many drawbacks, such as high time complexity in high dimensions and trapping in local minima, which make them inefficient in practice. modern or nontraditional optimization methods such as genetic algorithm and swarm intelligence are widely used in path planning problems [14-16]. particle swarm optimization (pso) is simple and fast because it has few parameters to be adjusted [17]. in the above mentioned works, the suggested methods have limitations and use the same basic equations of lspb. the lspb trajectory still deviates from the specified waypoints. in this work, the lspb trajectory is modified and engaged with pso. the novelty in this work is to modify lspb trajectory using two coefficients for calculating the time duration of the linear part in lspb trajectory. these coefficients are functions of velocities between through points. the velocities are obtained by pso to force the lspb trajectory passing exactly through the specified path points. also, relations for velocity correction and exact velocity solution are derived. 2. multisegment linear path with blends for the case in which there are many waypoints, linear segments with parabolic blends are considered. in lspb, the segment is divided into three parts: parabolic, linear, and parabolic; respectively (fig.1). considering the path waypoints which are j, k, and 1. the time duration for blend region of point k is tk. the time duration for linear part between points j and k is tjk. the time duration of the segment which connects points j and k is tdjk. according to fig. 1, the linear velocity between points j and k is jkθ& , the acceleration at point k is kθ&& , and the path point position is kθ . the blend times tk is computed from the given: path points kθ , desired time durations tdjk, and the magnitude of acceleration kθ&& . for interior path points, this follows simply the equations [2]: djk jk jk t θθ θ − =& …(1.a) kjkklk sgn θθθθ &&&&&& )( −= …(1.b) k jkkl kt θ θθ && && − = …(1.c) kjdjkjk tttt 2 1 2 1 −−= …(1.d) where sgn ( ) returns the sign of the value in the brake. in the first and last segments there is an entire blend region at one end of the segment. for the first segment [2]: 1121 )( θθθθ &&&& −= sgn … (2.a) 1 122 12121 )(2 θ θθ && − −−= dd ttt …(2.b) 112 12 12 2 1 tt d − − = θθ θ& …(2.c) 211212 2 1 tttt d −−= …(2.d) djkt dijt kt klθ&=slopejkθ&=slope jkt θ iθ iθ jθ kθ lθ t j i l k fig. 1. multisegment linear path with blends [2] likewise, for the last segment (the one connecting points n-1 and n), which leads to the solution: nnnn sgn θθθθ &&&& )( 1 −= − …(3.a) saad zaghlul saeed al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 7789 (2018) 79 n nn nndnndn ttt θ θθ && )(2 12 )1()1( − −− − +−= …(3.b) nnnd nn nn tt 2 1 )1( 1 )1( − − = − − − θθ θ& …(3.c) 1)1()1( 2 1 −−− −−= nnnndnn tttt …(3.d) in these linear-parabolic-blend splines, when acceleration capability is sufficiently high, the paths will come quite close to the desired waypoint. the manipulator must come to a complete stop if it is desired to pass exactly through a waypoint. the term "through point", as it was mentioned in [2], will be used in the next sections to specify a path point through which the manipulator is forced to pass exactly. 3. problem definition in the previous section, the lspb trajectory is constrained to the following [6]: 1-the velocity at the first and last through point must be zero. 2-the velocity and acceleration of the trajectory must be: maxmax )()( θθθθ &&&&&& ≤∧≤ tt . the limitations of this algorithm are: 1-sufficiently large acceleration is required so as to obtain linear portion in the segment. 2-the manipulator's velocity must be zero so as to pass into waypoints. 3the system should generate two pseudo points so as to make the manipulator passes exactly through a path point without stopping. 4-the parabolic portion is assumed to be centered equally in time about through point. this later assumption makes the apex of parabolic part to be shifted away from through point as shown in fig. 2. for interior path point (equation (1)), the apex of the parabolic portion is not equally centered in time about waypoint. this can be easily proved using the kinematic equations for lspb trajectory as presented below. 1θ& 2θ& 0=θ& fig. 2. trajectory of parabolic part. proof 1: ,0and,0,0given 21 <<> θθθ &&&& the velocities at the parabolic path for constant acceleration are: abtθθθ &&&& −=− 12 …(4.a) atθθθ &&&& −= 1 …(4.b) btθθθ &&&& −=− 2 …(4.c) where 21 and,, θθθ &&& are the velocities of previous segment, apex point, and next segment; respectively. but when the trajectory changes its direction, the apex point's velocity becomes zero. the above equations of velocities are solved for unknown time durations as: θθ &&& /1=at …(5.a) θθ &&& /2=bt …(5.b) ba tt ≠∴ …(5.c) therefore the apex of parabolic path is not exactly placed under a waypoint unless 21 θθ && = in magnitude. 4. proposed method the assumption of normal lspb that parabolic portion is centered in time around waypoints is replaced in this work by proposed coefficients which are functions of velocities between through points. from equations (4 and 5), the time durations on the parabolic blend around through point are obtained as: θθθ θθ &&&& &&& /)( / / 21 1 + =aba tt )( / 21 1 θθ θ && & + =aba tt …(6.a) saad zaghlul saeed al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 7789 (2018) 80 )( / 21 2 θθ θ && & + =abb tt …(6.b) from equation (6), now two coefficients (αj & αk) are obtained for calculating the time duration of the linear portion of the trajectory. these coefficients are obtained from the lspb kinematic equations. two coefficients are used to calculate the time's duration of the parabolic portions in the segment's time duration (tdjk). given through points (joint's angles), time durations, and assuming accelerations for all through points, the modified lspb equations are as below: modified mid segments kjkklk θ/θθt &&&& )( −= …(7.a) kkjjdjkjk tαtαtt −−= …(7.b) )( jkijjkj θθ/θα &&& += …(7.c) )( kljkjkk θθ/θα &&& += …(7.d) modified first segment 1121 θ/θt &&&= …(8.a) 2211212 tαttt kd =−−= …(8.b) )( 2312122 θθ/θα &&& += …(8.c) modified last segment n)n(n-n θ/θt &&& 1−= …(9.a) nnnjnndnnttαtt −−= −−=− 11)1()1( …(9.b) )( )1()1)(2()1(1 nnn-n-nnnθθ/θα −− += &&& …(9.c) by using these coefficients, the apex of parabolic portion is positioned exactly under the through point. although the apex of parabolic part is now positioned exactly under through point, but it stills not passing through it. this is because of replacing a linear part region of the segment by parabolic part. this can be proved as below. proof 2: the position for linear part with constant velocity during a time t is t θ ll ⋅= θ& …(10) and that for parabolic part with constant acceleration in the same time duration is: 2 2 1 tθt θ lp &&& −⋅= θ …(11) the difference (δθ) between these parts is: lp θθθ −=∆ …(12) substituting equations (10) and (11) into equation (12) gives: ttθtθ ll ⋅−−⋅=∆ θθ &&&& 2 2 1 2 2 1 tθθ &&−=∆ …(13) which means this displacement of parabolic part is less than that of linear part for same time duration. this problem can be solved by increasing the velocity between through points in presence of acceleration limits. the problem of finding the velocities' value can be solved by optimization methods such as pso. 4.1. velocity correction in the above modified lspb, the initial velocities are obtained from equation (1). but from proof 2, there is an error due to the parabolic part (equation (13)). therefore, these velocities can be corrected by adding the change of velocity (equation (14.b)) based on the error of the parabolic parts as: jkjkjk θθθ &&& ∆+=corrected)( …(14.a) jkjkjkjk tsgn /)( θθθ ∆=∆ && …(14.b) )) 2 1 () 2 1 (( 2 1 22 kkjjjk tt ⋅+⋅=∆ θθθ &&&& …(14.c) in the above equation, half of the blend durations (tj and tk) are accepted as an approximated value. this corrected velocity is used as initial velocity to begin the optimization process. 4.2 exact solution of velocity the lspb offers exact solution of velocity for path segment when there is acceleration from zero velocity to linear velocity and deceleration to zero velocity. for example, the first and second segments (ij and jk) or the second and third segments (jk and kl) have such situation (fig.1). the second and third segments are considered to derive a general solution. let ts, tl, and te are times' duration for first parabolic part, linear part, and last parabolic part for the path from through point j to through point k. the total displacement is the summation of these three parts as below: 2/2/ 22 eklexactsjjk ttt θθθθθ &&&&& ++=− …(15.a) esdjkl tttt −−= …(15.b) jexactst θθ &&& /= …(15.c) kexactet θθ &&& /= …(15.d) saad zaghlul saeed al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 7789 (2018) 81 solving the above quadratic equation (equation (15.a)) for the exact velocity to obtain: ⋅ ⋅+ ⋅+⋅−−−+ = )/()( )/()(22 kjkj kjkjjkdjkdjk exact tt θθθθ θθθθθθ θ &&&&&&&& &&&&&&&& & )( jksgn θθ − …(16) in the above derivation, absolute values are used to prevent sign confusion. the sign of velocity is introduced after solving the quadratic equation. 4.3. steps of proposed method the proposed modified lspb is presented here which overcomes the limitations of the normal lspb. it provides logic sequence for computer programming to generate through points: step 1: calculate velocities and accelerations according to equation (1). step 2: use equation (16) to solve for exact velocity if there is a change in velocity direction between two following through points. step 3: obtain the time durations for the trajectory using equations (7-9). step 4: apply velocity correction using equation (14) to all calculated velocities at step 1 except that obtained at step 2. step 5: use these velocities as initial solution for the optimization process. this algorithm can be easily converted into computer program to perform optimization process (fig. 3). the velocities are obtained from optimization process so as to force the lspb trajectory passing exactly through specified path points. nnn tttt 1121 ...,,,...,,calculate − (16)eq.fromfor 1+iiθ& nnndn tt θθθθ &&&& ..., ,,...,,,...,, 11121 − nnn θθθθ &&&&&& ..., ,,...,,calculate 1112 − (14)eq.fromfor 1+iiθ& fig. 3. algorithm flowchart for proposed modified lspb trajectory. 5. particle swarm optimization recently, modern or nontraditional methods of optimization are widely used for solving different optimization problems. edward and kennedy formulated pso in 1995. the process was inspired by the social behavior of animals, such as bird flocking or fish schooling. each particle has two characteristics which are: a position and a velocity. it must remember the best position in terms of objective function value. the particles adjust their individual positions and velocities by sharing the received information of the best position [18]: saad zaghlul saeed al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 7789 (2018) 82 22 old , bestlocal ,11 old , new , rγ)(rγ ×+−××+= jijijiji w ppvv )( old , bestglobal , jiji pp −× …(17.a) new , old , new , jijiji vpp += …(17.b) where v is particle's velocity, w is inertia weight, p is particle position or variable, r1 and r2 are uniform distributed random numbers, plocal best is best local postion, pglobal best is best global position, i is particle index, j is dimension of variable, γ1 is individual learning rate, γ2 is group learning rate. premature and local optimum convergence are the disadvantages of traditional pso. modifications to pso were applied so as not to skip the optimal solution [19]. these modifications are happened either on basic components or on swarms itself. modifications on basic components of pso are: inertia weight [20, 21], velocity constriction [22, 23], and velocity clamping [24]. five basic benchmark optimization functions had been tested by using fifteen different inertia weight variants in [25]. they concluded that chaotic inertia weight improves the accuracy of the solution. modifications on the swarms itself are: insertions new swarms [26, 27], mutation [28], and swarm initiation [29]. these modifications can increase the search diversity. applying multiple modifications on the basic components of pso and swarms was suggested as future work in [30]. an improved chaotic pso algorithm based on adaptive inertia weight (aiwcpso) was proposed in [31]. initially, the positions and velocities of the population are generated by using chaotic mapping. the inertia weight is adjusted according to the values of: iterative number, aggregation degree factor, and improved evolution speed parameter. aiwcpso algorithm with chaotic swarm initiation and swarm injection were used in [32]. this combines modifications to basic components of pso and swarms. in this work, improved chaotic pso algorithm based on adaptive inertia weight (aiwcpso) is used. also velocity constriction factor, λ, is included (equation (18)). new , old , new , jijiji vpp λ+= …(18) steps of aiwcpso algorithm step 1: cubic mapping (equation (19)) is used to generate double or triple swarm size as chaotic initialization. the cubic mapping is described as following:    <<− −=+ 11 34 0 3 1 p ppp nnn …(19) where p0 is a random number substituted as initial value. these swarms are tested so as to select those of best fitness as initial solution to particle position. then this initial solution is mapped to the search space range. step 2: chaotic initialization is also applied to generate n initial velocities by cubic mapping (equation (19)). step 3: the inertia weight is updated by the equations below for a single particle: ( ) ( )adfesf i ie iter iter wwww βα −−−−= max minmaxmax …(20.a) )()( )]()([ 1 1 − − + − = k i k i k i k i i pbestfabspbestfabs pbestfpbestfabs esf …(20.b) )],([max )],([min k avg k best k avg k best ffabs ffabs adf = …(20.c) where k is the current iteration value. wmax and wmin are maximum and minimum values of inertia weight; respectively. iter is the current iteration number and itermax is the maximum number of iteration. the value α and β has the range [0,1]. esfi is the improved evolution speed parameter of particle i (i =1, 2,..., n), adf is the aggregation degree factor of swarm, f (pbesti k) is the best fitness value of particle i at the kth iteration, fbest is the best fitness obtained from all particles, favg is the mean fitness of all particles in the swarm at the same iteration. step 4: the variance (σ) is calculated for the population's fitness (equation (21)). when variance is less than threshold value and the optimal fitness of current iteration is worse than the desired fitness value, chaotic disturbance is applied. ∑ = − − = n i k avg k i k avg k i fxfabs fxf 1 22 ) ]1]],)([[[maxmax )( (σ …(21) where f( xi) is fitness values of particle i. step 5: chaotic disturbance strategy: cubic mapping (equation (19)) is used to generate chaotic vector oij (i =1, 2,..., n; j =1,2,..., j), where o0j is (-1,1) of random numbers, and the component of this vector is loaded to the range of chaotic disturbance of [−γj, γj ] (j=1, 2,..., j). then chaotic disturbance variation is δpi = (γ1 oi1, γ2 oi2 ,...,γj oij). the position updated of particle after adding the chaotic disturbance variation is given by: pbij (k +1) = pij (k) + vij (k) + δpij. finally, comparison is made between the fitness values of f(pbi (k +1)) and f (pi (k +1)). if f(pbi (k +1)) is saad zaghlul saeed al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 7789 (2018) 83 better than f(pi (k +1)), then pi (k +1) is updated by pbi (k +1). note: j is the variable's dimension of particle i. for more details about aiwcpso algorithm see [31]. 6. simulation results simulations are presented to validate the proposed method. these simulations are implemented in matlab7 on pentium 4 pc processor (intel (r) core (tm) i5-2450m cpu @ 2.50 ghz). the parameters of pso are set as follows: γ1=2.05; γ2=2.05; λ=0.7298 [22]; n= 40; itermax= 30; wmax=0.09, wmin= 0.05; α=0.99; β=0.01; γ=10-4; threshold value= 10-5; desired fitness value =10-12. the objective function to be minimized has the form: ∑ = = np i ie 2 2fitness …(22) where e is the error at through point, np is total number of through points. the error at through point 1 is always zero because it is starting point. considering a single joint: through points of the path in degrees: 10, 35, 25, 10. the time durations of the segments are: 2, 1, 3 seconds; respectively. the acceleration at blend points is 50 degrees/second2. although different accelerations at different through points can be used. at first, the trajectories of normal lspb (equations (1-3)) and modified lspb (equations (7-9)) are compared (fig. 4). the normal lspb trajectory is shifted while the modified is equally spaced about through points. a comparison of linear part velocities is presented in table 1 for 50 degrees/second2 acceleration between normal lspb, modified lspb with velocity correction, and optimum modified lspb (section 4.3). it is clear that modified lspb with velocity correction is better choice as initial velocity to begin the optimization process. a range between 0.9 to 1.2 of these later calculated velocities is used as initial value for the optimization. this will reduce the number of iterations to reach optimum solution. pso is used to generate optimal linear velocities for the linear parts. in fact, that increasing the velocities of the linear portions will compensate the error resulted from inserting parabolic region in the path between two neighboring through points. figure 5 shows comparison between the normal and modified lspb trajectories using pso method. the normal lspb trajectory deviates from the through points, while the engagement of modified lspb with pso (proposed method in section 4.3) passes into them. in the normal lspb method, it is restricted to use acceleration's value higher than 40 degrees/second2 [2]. figure 6 shows results of proposed method for the two acceleration values using pso. the results of comparison are presented in table 2 for different acceleration values. acceleration values are: 30, 50, 70 degrees/second2. fig. 4. trajectories of normal and modified lspb table 1, comparision of linear velocities. method velocity normal lspb (eqs.1-3) modified lspb & velocity correction (eqs. 7-9&14) modified lspb & pso (eqs. 7-9) & (eqs. 14, 1624) 12θ & (deg/sec) 13.3975 14.3854 14.6446 23θ & (deg/sec) -10.0000 -11.8111 -11.5306 34θ& (deg/sec) -5.0862 -5.1090 -5.0728 t1 (sec) 0.2679 0.2877 0.2929 the error at through points is reduced for the cases of proposed method. the error at point 2 is zero because of using the exact velocity solution (equation (16)). the error at point 3 is 0.2916∙1012, 0.3588∙10-12, and 0.0107∙10-12 degree for accelerations 30, 50, and 70 degrees/second2; respectively. optimal velocities' value are presented in table 3. 0 1 2 3 4 5 6 10 15 20 25 30 35 40 time (sec) p o si ti o n ( d eg re e) through point normal modified 1.8 1.9 2 2.1 2.2 2.3 33 34 35 saad zaghlul saeed al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 7789 (2018) 84 table 2, comparison of error at through points between normal and modified lspb using pso. case acceleration (deg/sec2) e2 (deg) e3 (deg) e4 (deg) normal lspb (eqs.1-3) & pso (eqs. 17-22) 30 0.7919 0.9480 0.6877 50 0.3785 0.5844 0.5021 70 0.2539 0.4010 0.3431 proposed method (eqs. 7-9 & eqs. 14, 16-24) 30 0.0003∙10-12 0.2916∙10-12 0.3038∙10-12 50 0.0002∙10-12 0.3588∙10-12 0.5524∙10-12 70 0.0001∙10-12 0.0107∙10-12 0.5240∙10-12 fig. 5. comparison between normal and modified lspb trajectory using pso. 0 1 2 3 4 5 6 10 15 20 25 30 35 40 time (sec) p o si ti o n ( d e g re e ) through point acceleration=50 acceleration=30 fig. 6. trajectories obtained by proposed method. table 3, optimal values obtained by proposed method. variable acceleration (deg/sec2) 30 50 70 12θ & (deg/sec) 17.7526 14.6446 13.8751 23θ & (deg/sec) -13.9218 -11.5307 -10.9786 34θ& deg/sec) -5.1142 -5.0728 -5.0525 t1 (sec) 0.5918 0.2929 0.1982 the run execution time is found to be about 5.4% of the first parabolic portion (0.2929 seconds) for the 50 degrees/second2 acceleration. this value is enough to generate trajectory of desired path by using the algorithm of the proposed method for on-line path planning. point to point position trajectory is simulated for two-link planar robot manipulator (fig. 7). it has revolute joints. the masses m1 and m2 are assumed to be concentrated at the distal end of the links which have the lengths l1 and l2; respectively. the robot starts at point (2.95, 0.05) and passes through points (2.45, 0.05) and (2.7, 0.30). then it stops at point (2.95, 0.05). all coordinates are in meters. the time durations are: 4, 3, 3 seconds. the robot dynamic equation and controller are taken from early published paper [33]. the desired through points in joint space are obtained by solving the inverse kinematics equations [2]. the trajectory for the two joints is generated by using the proposed method (fig.8). 0 1 2 3 4 5 6 6 12 18 24 30 36 time (sec) p o si ti o n ( d eg re e) throug point normal proposed 1.8 2 2.2 2.4 32.5 33 33.5 34 34.5 35 35.5 saad zaghlul saeed al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 7789 (2018) 85 fig. 7. planar robot arm with two links [2] 0 2 4 6 8 10 -60 -40 -20 0 20 40 60 time (sec) p o si ti o n ( d e g re e) joint 1 joint 2 fig. 8. two-link joint's desired trajectory obtained by proposed method. the cartesian trajectory of the two-link manipulator is presented in fig. 9. the errors in the cartesian space are: 0.5722∙10-5, 0.4180∙10-5, 0.4365∙10-5, and 0.2551∙10-5 in meters for these through points. the error at the starting point is not zero because of the used controller which is learning on-line. the error at through points is presented in table 4. finally, a comparison of results is presented for path of acute angles from [12]. the pattern contains 14 line segments, and beginning at the origin. the segments form angles starting at 125° and decrease linearly to 5°. the peak velocity error shown in fig. 10 increases as angle decreases. for example, a complete change in direction or a 0° angle results in a 100% error according to the method of [12]; while the error is no more 21% by using the proposed method in this work. in lspb, the trajectory deviates slightly from the straight path. this deviation is increased as the angle formed by two segments is decreased (fig. 11). table 4, error at through points for point to point trajectory using the proposed method link error (deg) e2 e3 e4 1 0.0071∙10-12 0.2061∙10-12 0.1474∙10-12 2 0.0284∙10-12 0.1137∙10-12 0.0675∙10-12 2.4 2.5 2.6 2.7 2.8 2.9 3 0.05 0.1 0.15 0.2 0.25 0.3 0.35 x (m) y ( m ) actual trajectory through point fig. 9. two-link cartesian path obtained by proposed method. 0 5 10 15 20 25 30 0 20 40 60 80 100 time (sec) s p ee d e rr o r (% ) reference [12] proposed method fig. 10. comparison of speed error resulting from decreasing segment angle saad zaghlul saeed al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 7789 (2018) 86 0 5 10 15 20 25 30 0 2 4 6 time (sec) y ( m m ) desired trajectory proposed method fig. 11. trajectory of y-component with decreasing segment angles. 7. conclusions the normal lspb is restricted to that the acceleration must be sufficiently high. in this work, modified lspb is engaged with pso for generating smooth valid trajectories that passes through specified path points while satisfying velocity and acceleration constraints of physical mechanical robot manipulator. increasing the velocity of linear portions compensates the error due to inserting parabolic part. velocity correction is used to obtain close values to the optimal solution. this reduces the number of iterations to obtain the optimum solution. also, exact solution of velocity can be used for lspb path segment when there is acceleration from zero velocity to linear velocity and deceleration to zero velocity. simulation results show that the proposed method to work well on the tested cases. the error at through points is almost zero. advantages of the modified lspb algorithm are: through points can be created, easily engaged with optimization method, very simple which can be used for online path planning, and not necessarily to use high acceleration's magnitude. the proposed method in this work has no chance to fail to create through points within a reasonable number of iterations. 8. references [1] ellekilde, l. p. and petersen, h. g. (2013). motion planning efficient trajectories for industrial bin-picking. international journal of robotics research, 32(9-10): 991-1004. [2] craige, j. j. (2005). introduction to robotics: mechanics and control. new jersey. person prentice-hell, inc. [3] siciliano, b., sciavicco, l., villani, l. and oriolo, g. (2009). robotics: modelling, planning and control. london. springerverlag: pp.168. [4] ata, a. a. and sa'adah, m. y. (2006). december 8. soft motion trajectory for planar redundant manipulator. 9th international conference on control, automation, robotics and vision. singapore. [5] xianhua, l., shili, t., xiaowei, f. and hailiang, r. (2009). december 19-20. lspb trajectory planning: design for the modular robot arm applications. ieee international conference on information engineering and computer science. wuhan. doi: 10.1109 / iciecs. 2009.5365861:1-4. [6] kunz, t. and stilman, m. (2011). turning paths into trajectories using parabolic blends. gt-golem-2011-006. georgia institute of technology. [7] kunz, t. and stilman, m. (2012). timeoptimal trajectory generation for path following with bounded acceleration and velocity. proceedings of robotics: science and systems. sydney, austria. doi: 10.15607 / rss.2012.viii.027: 9-13. [8] rymansaib, z., iravani, p. and sahinkaya, m.n. (2013). july 9-12. exponential trajectory generation for point to point motions. ieee/asme international conference on advanced intelligent mechatronics, wollongong-australia, pp.906-911. [9] rossi, c. and savino, s. (2013). robot trajectory planning by assigning positions and tangential velocities. elsever: robotics and computer-integrated manufacturing. 29: 139156. [10] kröger, t. and wahl, f. m. (2010). online trajectory generation: basic concepts for instantaneous reactions to unforeseen events. ieee transactions on robotics, 6(1): 94-111. [11] kröger, t. (2012). may 14-18. on-line trajectory generation: nonconstant motion constraints. international conference on robotics and automation, river center, saint paul, minnesota, usa. doi: 10.1109 / icra. 2012.6225186: 2048-2054. [12] thompson, b. and yoon, h.-s. (2014). efficient path planning algorithm for additive manufacturing systems. ieee transactions on components, packaging and saad zaghlul saeed al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 7789 (2018) 87 manufacturing technology, 4(9): 1555-1563, doi: 10.1109/tcpmt.2014.2338791 [13] weber, w., könig, a., nodem, d. x., darmstadt, h. (2016). june 21 – 22, 2016. user-defined transition between path segments in terms of tolerances in speed and position deviation. proceedings of isr 2016, 47st international symposium on robotics, munich-germany, pp.187-193. [14] masehian, e. and sedighizadeh, d. (2010). multi-objective psoand npso-based algorithms for robot path planning. advances in electrical and computer engineering, 10(4): 69-76. [15] bailón1, w. p., cardiel1, e. b., campos, i. j. and paz1, a. r. (2010). september 8-10. mechanical energy optimization in trajectory planning for six dof robot manipulators based on eighth-degree polynomial functions and a genetic algorithm. 7th international conference on electrical engineering, computing science and automatic control. méxico: 446 – 451. [16] gong, d., lu, l. and li, m. (2009). may 1821. robot path planning in uncertain environments based on particle swarm optimization. ieee congress on evolutionary computation. trondheim. doi:10.1109/cec.2009.4983204: 21272134. [17] pedersen, m. e. h. and chipperfield, a. j. (2010). simplifying particle swarm optimization. applied soft computing, 10(2): 618-628. [18] rao, s. s. (2009). engineering optimization theory and practice. new jersey. john wiley & sons, inc.: 4th edition, pp. 708. [19] chavan, s.d. and adgokar, n.p. (2015). an overview on particle swarm optimization: basic concepts and modified variants. international journal of science and research, 4(5): 255-260. [20] alfi, a. (2012). particle swarm optimization algorithm with dynamic inertia weight for on-line parameter identification applied to lorenz chaotic system. international journal of innovative computing, information and control, 8(2):1191-1203. [21] djoewahir, a., kanya, t. and shenglin, m. (2012). a modified particle swarm optimization with nonlinear decreasing inertia weight based pid controller for ultrasonic motor. international journal of innovation and technology, 3(3): 198-201. [22] tian, d. (2013). a review of convergence analysis of particle swarm optimization, international journal of grid and distributed computing, 6(6): 117-128. [23] malwiya, r. and rai, v. (2015). optimal speed controlling of induction motor using new pso. international journal of advanced technology & engineering research, 5(2): 39-43. [24] ibrahim, n.m.a., atti, h.e.m., talaat, h.e.a. and alaboudy, a.h. k. (2015). modified particle swarm optimization based proportional-derivative power system stabilizer. international journal of intelligent systems and applications. doi: 10.5815 / ijisa. 2015. 03.08: 62-76. [25] bansal, j.c., singh, p. k., saraswat, m., verma, a., jadon, s. s. and abraham, a. (2011). october 19-21. inertia weight strategies in particle swarm optimization. ieee 3rd world congress on nature and biologically inspired computing. salamanca. doi: 10.1109 / nabic. 2011. 6089659: 633640. [26] yang, c. h., tsai, s. w., chuang, l. y. and yang, c. h. (2011). a modified particle swarm optimization for global optimization. international journal of advancements in computing technology, 3(7): 169-189. [27] elsayed, s. m., sarker, r. a. and montes, e. m. (2013). june 20-23. particle swarm optimizer for constrained optimization. ieee congress on evolutionary computation. cancun-mexico. doi: 10.1109/cec.2013.6557896: 2703-2711. [28] ratanavilisagul, c. and kruatrachue, b. (2014). a modified particle swarm optimization with mutation and reposition. international journal of innovative computing, information and control, 10(6): 2127-2142. [29] tian, d. (2015). particle swarm optimization with chaotic maps and gaussian mutation for function optimization. international journal of grid and distributed computing, 8(4): 123-134. [30] jamous, r.a., tharwat, a.a., el-seidy, e. and bayoum, b.i. (2015). modifications of particle swarm optimization techniques and its application on stock market: a survey. international journal of advanced computer science and applications, 6(3): 99-108. [31] li, j., cheng, y., and chen, k. (2014). may 31-june 2. chaotic particle swarm optimization algorithm based on adaptive inertia weight. 26th chinese control and decision conference. changsha. doi: 10.1109 /ccdc. 2014. 6852369: 1310-1315. saad zaghlul saeed al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 7789 (2018) 88 [32] al-khayyt, s. z. s., m. a. abdilatef, z. m. yosif (2016). visual tracking enhancement of object on circular path based on tuned kalman filter by particle swarm optimization. international journal of computer applications. 146(4): 43-50. [33] al-khayyt, s. z. s. (2013). tuning pid controller by neural network for robot manipulator trajectory tracking. alkhwarizmi engineering journal, 8(2): 19-28. )2018( -89 77، صفحة1د، العد14دزمي الهندسية المجلجلة الخوارم سعد زغلول سعيد 89 َخْلق نقاِط بينية في الدالة الخطيِة المندمجة مع مسار القطع المكافىِء بطريقِة تحقيِق األمثلية الخياط سعد زغلول سعيد جامعة الموصل / كلية الهندسة / قسم الميكاترونكس alkhyaat@yahoo.comالبريد األلكتروني: الخالصة كفاية. من مسار القطعة الخطية المندمجة مع مسار القطع المكافئ ينحرف عن المسار المخطط و هو مقيد بقيمة تعجيل يجب ان تكون كبيرة بما فيه الأن موجودة حاليا حول الموضوع غير قابل للتطبيق مباشرة على ناحية أخرى، التعامل مع مسار القطعة الخطية المندمجة مع مسار القطع المكافئ في المقاالت ال السرب لتوليد نقاط المسارات الحركية. في هذا العمل، اقترح تعديل على مسار القطعة الخطية المندمجة مع مسار القطع المكافئ و تم تعشيقه مع أمثلة جسيم لمتساوي لزمن مسار القطع المكافئ حول نقطة المسار، استبدلت بمعامالت مقترحة لحساب عبر المسار. أن الطرق السابقة التي تعتمد على فرضية التوزيع ا قطع المكافئ المطور الفترة الزمنية لمسار القطعة الخطية. هذه المعامالت هي دوال من السرع بين نقاط المسار. أن مسار القطعة الخطية المندمجة مع مسار ال لمسار التي تستحصل بطريقة امثلية جسيم السرب إلجبار مدبر الروبوت على المرور خالل نقاط المسار المحددة أخذا بنظر يستخدم السرع بين نقاط ا نتائج المحاكاة العددية السرعة و معادالت لحساب السرعة الفعلية. حكذلك تم اشتقاق عالقات لتصحياالعتبار تقيدي السرعة و التعجيل للروبوت المستعمل. المقترحة هذه الطريقة وان يعمل بشكل جيد في االختبارات. مع أمثلة جسيم الحشد المسار الخطي المندمج مع مسار القطع المكافئ المطور تعشيق ان أظهرت بسيطة جدا و يمكن ان تستعمل لتخطيط المسار مباشرة و غير ضروري فيها استخدام قيمة تعجيل كبيرة. math.model-1 hayder mohammed abdul-hameed /al-khwarizmi engineering journal ,vol.1, no. 2,pp 103-109 (2005) ١٠٣ al-khwarizmi engineering journal al-khwarizmi engineering journal, vol.1, no.2,pp 103-109, (2005) mathematical modeling for the clarifier units and turbidity parameters in al-karama treatment plant hayder mohammed abdul-hameed environmental engineering department college of engineering/ university of baghdad (received 25 september 2005; accepted 7 november 2005) abstract: the high cost of chemical analysis of water has necessitated various researches into finding alternative method of determining portable water quality. this paper is aimed at modelling the turbidity value as a water quality parameter. mathematical models for turbidity removal were developed based on the relationships between water turbidity and other water criteria. results showed that the turbidity of water is the cumulative effect of the individual parameters/factors affecting the system. a model equation for the evaluation and prediction of a clarifier’s performance was developed: model: t = t0(-1.36729 + 0.037101∙10λph + 0.048928t + 0.00741387∙alk) the developed model will aid the predictive assessment of water treatment plant performance. the limitations of the models are as a result of insufficient variable considered during the conceptualization. keywords: performance evaluation, ph, alkalinity, mathematic model, simulation 1. introduction tebbutt (1983) describes water as the world’s most important natural resource since without it life cannot exist and industry operate. unlike many other resources, it has no substitute in many of its uses. water plays an essential role in community development since a reliable supply is a prerequisite for establishing a permanent settlement. there is a vast amount of water present in the earth and its’ surrounding atmosphere. about 7% of the earth’s mass is made up of water. 97% of this is found as saline water in oceans, about 2.3% is in the polar caps and only 0.7% exists in fresh water lakes, rivers, aquifers and in the atmosphere. water that is pure is not found in nature; even water vapour condensing in air contains solids and dissolved gases (tebbutt, 1983). as it condenses and falls, it sweeps up other materials from the air, it becomes still more contaminated on reaching the ground, as it runs running over soil surface and percolate the soil strata. waste from human activities, either industrial or domestic, according to tchobanoglous and burton (1991), introduce even more pollutants, than any natural sources, into water bodies. since the available water is seldom found in conditions that meet potable specifications, a treatment plant is clearly necessary to improve the water quality. water supply to a community goes through the following stages; the community water demand is carefully estimated with allowances for population growth; the most suitable raw water source is identified and analysed; then a hayder mohammed abdul-hameed /al-khwarizmi engineering journal ,vol.1, no. 2,pp 103-109 (2005) ١٠٤ water treatment plant to effect the required changes is designed, constructed and operated along with it’s distribution network. when online, a periodic review of plant performance is undertaken to ascertain if, or otherwise, the plant works according to prediction. hammer (1973) and cairncross (1980) both agree that record–keeping and periodic reviews of plant performance are necessary decision tools when the plant requires expansion or when operational problems arise. the aim of this paper is to model water turbidity as function of several other parameters that will aid in assessing the performance of a al-karama water treatment plant over a period of time and to suggest ways of improving plant performance 2. experimental work and procedure al-karama drinking water treatment plant located on the western-bank of tigris river in al-karkh district and the water supplies to the plant by four in river intakes, the plant consists of 20 clarifiers that their functions are to reduce the solid content in the water coming from the river to pass through the sub-sequent treatment stages till pumps through the network. the sampling procedure followed the way of sampling from the basin mentioned in the standard method of water analysis all and all the test were done on – line near the basins to reduce the physical effects of the surrounding on the results. determination of temperature the temperature of the sample of water was determined with the aid of thermometer, beakers, and electrodes. determination of turbidity this involves the use of turbid meter. the sample cells were washed with sample water, and was discarded and refilled with the same sample. determination of ph the ph of the sample was determined with aid of colormetric comparator. determination of total alkalinity the total alkalinity was determined using titration. 3. modelling for turbidity removal for a constant flow rate and a fixed set of conditions the suspended solids (and hence turbidity) removal is a fixed fraction of inlet suspended solid. assuming also, in accordance with belan (1988), that for mildly contaminated rivers the suspended solid is linear with turbidity i.e. that the particle size and type distribution is constant over a time period. then turbidity removal (t0 –t)/t0 = k0 …(1) where t = turbidity of clarified water, t0 = turbidity of aerated water, k0 = constant 1 – (t/t0) = k0, t/t0 = 1 k0 = k', t = t0∙k' ….(2) in reality operating conditions do vary. therefore k' is only one of the function by which water quality may be measured. other essential parameters according to nikoladze et al (1989) are temperature (t), ph and alkalinity (alk). it is well established that these parameters exhibit independent and cumulative effect on t. effect of water temperature water molecules and impurity particles are in thermal brownian motion whose intensity is directly proportional to temperature (nikoladze et al, 1989). it is clear that the probability of collision of individual particles with one another and their consequent aggregation depend on their relative velocities i.e. on thermal brownian motion (and therefore on water temperature). again, it shall be assumed that the temperature profile within the clarifier is constant and is equal to that of the clarified water samples. hayder mohammed abdul-hameed /al-khwarizmi engineering journal ,vol.1, no. 2,pp 103-109 (2005) ١٠٥ (t0 t)/t0 ~ t …(3) where t = temperature in °c. effect of alkalinity turbidity removal is preceded by and dependent on the formation of chemical flock. the equation of the overall process as simplified by hammer (1975) is al2(so4)3 + 3ca(hco3)2 → 2al(oh)3 + 3caso4 + 6co2 obviously, good coagulation is dependent on the presence of sufficient alkalinity (hco3 -) and therefore (t0-t)/t0 ~ alk (4) where alk = alkalinity of water in mg/l as caco3. effect of ph suspended matters in water are surface–charged particles and it is the function of the coagulant to neutralize the charges. different particles types have been seen to have a particular ph at which the net charge on them is zero and coagulation optimum (nikoladze et al 1989). this ph is the isoelectric point (phis). a large difference between ph of the water medium and phis confers greater anticoagulation properties. for clay and humus phis = 7.1 and 7.0 respectively. this effect is confirmed by graphs obtained by tebbutt (1983) where turbidity (color) removal is reduced as the water ph deviates from an optimum value of about 7.0. therefore it can be concluded that: (t0 t)/t0 ~ 1/(ph phis) ….(5) assuming phis as 7 then ph – 7 = ∆ph has a positive value. (t0 t)/t0 ~ 1/(-∆ph) ….(6) ph = log[h+], therefore a more appropriate form of the equation would be: (t0 t)/t0 ~ 1/10-∆ph … (7) an expression similar to this was used by belan (1988) to express the lime dosage required to being about a desired change in the ph of water to phis of its contaminants. introducing constants into equations 3, 4 and 7: (t0 t)/t0 = k1/10-∆ph …(8) (t0 t)/t0 = k2t . .. (9) (t0 t)/t0 = k3alk …(10) other factors, such as organic content do exert influence on turbidity removal; their contribution can be accounted for by the introduction of corrective coefficient. assuming that hydrodynamic conditions are approximately constant, the influences of temperature, ph, and alkalinity on the turbidity of water in a clarifier basin may be additive or multiplicative (lucey, 2000). however a change in one will cause disequilibrium in the overall turbidity. such changes are accounted for by the various constants. using the additive method: (t0 t)/t0 = k0 + k1/10-∆ph + k2t + k3alk …(11) from which: t = t0(1 k0 + ki/10-∆ph + k2t + k3alk) …(12) because 1 k0 is a constant, let us say k0 in place of: t = t0(k0 + k1/10-∆ph + k2t + k3alk) …(13) the values of these constants maybe determined using the least – square method for multiple regression as outlined below adapted from stroud (1995). the various effects of ph, temperature and alkalinity on turbidity removal may also be combined in a multiplicative or exponential manner since no evidence exists hayder mohammed abdul-hameed /al-khwarizmi engineering journal ,vol.1, no. 2,pp 103-109 (2005) ١٠٦ to suggest the relationship used. following from the same premise as before, a possible second model equation such as 61 could be developed. t = k0(t0∙10k1 δphi∙tk2∙alkk3) ..(26) comparison of the models results indicates their extent of validity. the constants k0, k1, k2, k3 could be obtained from the solution of the generated 4x4 matrix. the alternatively the developed models can be solved software packages such as polymath3 (himmelblau, 1996). the package was used to find the coefficients in both models. the developed models are presented below: t = t0(-1.36729 + 0.037101∙10λph + 0.048928∙t + 0.00741387∙alk) (model 1) t = 2.20673∙1011∙t0·100.045606∆ph·t5.35007·alk1.55059 (model 2) the graphical error analysis technique was then used as the criteria for selecting the bestfit model. 4. results the results of the various experimental methods are as presented in table 1. table 1 weekly water quality parameters values weeks quality parameters t0 t t ∆hπ alk 1 1.50 1.25 27.75 0.10 23.80 2 2.00 1.25 26.74 0.20 21.80 3 1.80 1.00 29.81 0.10 21.00 4 2.00 1.00 28.52 0.10 23.00 5 2.25 1.50 29.00 0.00 21.84 6 2.13 1.64 30.81 0.10 23.29 7 2.00 0.50 28.75 0.40 23.75 8 2.00 1.00 29.50 0.30 29.50 9 3.50 1.00 28.00 0.50 30.00 10 6.00 1.00 29.00 0.30 27.50 11 4.50 1.25 29.33 0.40 30.00 12 4.25 1.08 29.05 0.40 29.66 13 5.00 1.00 30.00 0.40 29.50 14 4.80 2.31 29.47 0.10 25.50 15 4.25 2.50 28.88 0.30 28.25 16 6.50 5.75 28.43 0.20 26.15 hayder mohammed abdul-hameed /al-khwarizmi engineering journal ,vol.1, no. 2,pp 103-109 (2005) ١٠٧ the simulated results from the models are presented in figure 1. fig. 1 comparative analyses of the experimental and simulated values from models 1 and 2 5. discussion results from table 1 showed that turbidity in the treated water fell short of standards (5ntu max.) on one occasion (5.75ntu) but the mean value of 1.56ntu is well within the guide line value (who,1985). the cause of this is most likely the high t0 and the consequent clarifier’s overload. this may also suggest that the clarifier was overdue for desludging. mathematical modeling of the clarifier’s performance based on additive and multiplicative models using the pre determined parameters gave models 1 and 2 respectively. model 1: t = t0(-1.36729+ 0.037101x 10λph + 0.048928t + 0.00741387.alk) model 2: t = 2.20673 · 10-11to · 100.045606 ph · t5.35007 · alk1.55059 simulation results of the models showed that model 1 to a large extent will give a better turbidity prediction. it showed also that factors affecting turbidity values are mainly independent in operation. the turbidity of water is the cumulative effect of the individual parameters/factors affecting the system. from model 1 the change in turbidity caused by one of the independent variables is the cumulative effects of individual contributions of t0 , t, and alk. in model 2 the relationship of the turbidity parameters is as the synergy or interdependence of the variables. the nature of the model 1 equation gives turbidity change a dimensionless significance. therefore k2 the coefficient of temperature t will have a unit of 1/oc. it could be defined as the change in ratio of inlet and outlet turbidity caused by changing the temperature of the clarifier by 1oc. the discrepancies between the experimental and simulated values could be attributed to the assumptions made during the formulating of the model. the numbers of variables considered were quite small. the influence of human activities, impact of environmental pollution/contamination etc. on the coagulation and settling processes and much other need to be considered to enhance the reliability of the model. hayder mohammed abdul-hameed /al-khwarizmi engineering journal ,vol.1, no. 2,pp 103-109 (2005) ١٠٨ 6. conclusion developed a model equation for the evaluation and prediction of a clarifier’s performance as is presented below: (model 1) t = t0(-1.36729 + 0.037101∙10λph + 0.048928∙t + 0.00741387∙alk) the limitations of the models are as a result of insufficient variables considered during the conceptualization process. 7. references 1. american society of civil engineers/american water works association (1990), water treatment plant design (2nd ed.) mc. graw hill, international, usa, p. 1-10. 2. anderson r. (1987), "sample pretreatment and separation", john wiley & sons international, n.y.c., p. 24-36. 3. cairncross s. & al (1981), "evaluation for village water supply planning", john wiley & sons inc. n.y.c., p. 2-15. 4. fair g., geyer j, okun d. (1968), "water and wastewater engineering", (vol.2), john wiley & sons inc. n.y.c., p. 27.1-27.12, 31.131.29. 5. hammer j.m. (1975), water and wastewater technology, john wiley & sons, inc, n.y.c., 1975, p. 222-261. 6. hellman h. (1981), "analysis of surface wate"r, (english ed.) ellis horwood limited, p. 316-319. 7. lucey t. (2000), "quantitative techniques", 5th ed., elst, ny. 8. midgley d., torrance k. (1991), "potentiometric water analysis", (2nd ed.), john wiley & sons international england, p. 55-89. 9. nikoladze g., mintis d., kastalsky a. (1989), "water treatment for public and industrial supply", (english ed.), mir publishers, moscow, p. 51-70, 89-107, and 213-224. 10. odigure j.o. (1998), "safety, loss and pollution prevention in chemical process industries", jodigs & associates, nigeria, p. 18-22. 11. owen h., sandall o.c. (1983), "computational methods in chemical". 12. tebbutt t.h.y. (1983), "principles of water quality control", 3rd ed., pergamon press, england, p. 1-50, 125-140, and 168-174. 13. tchobanoglous g., burton f.l. (1991), "wastewater engineering: treatment, disposal and reuse", 3rd ed., mc graw hill, international, calif., p. 104-108. 14. twort a.c., law f.m, crowley f.w. (1985), "water supply", 3rd ed., edward arnold publishers ltd., germany, p. 200-241. hayder mohammed abdul-hameed /al-khwarizmi engineering journal ,vol.1, no. 2,pp 103-109 (2005) ١٠٩ التمثيل الرياضي للعوامل الموثرة على عكورة المياه في احواض الترويق في مشروع ماء الكرامة حيدر محمد عبد الحميد كلية الهندسة/ جامعة بغداد قسم الهندسة البيئية :الخالصة حيث اعتمد , لمزالة في احواض الترويقيهدف البحث الى ايجاد تمثيل رياضي للعوامل المؤثرة على العكورة ا التمثيل الرياضي على العالقة بين عكورة الماء وباقي العوامل الفيزياوية االخرى وقد وجد من العالقة الرياضية ان عكورة ق الماء تتاثر بصورة كبيرة وتراكمية لبعض المؤثرات الفيزياوية وقد تم ايجاد معادلة رياضية لتقيم اداء احواض التروي . اعتمادا على العكورة المزالة حوراء وعدنان al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 7, no. 4, pp41-53 (2011) the estimation of vibrational energy of two coupled (welded) plates using statistical energy analysis adnan d. mohammed hawraa s. ibraham department of control and system engineering/university of technology (received 24 march 2011; accepted 24 august 2011) abstract this paper deals with a method called statistical energy analysis that can be applied to the mechanical and acoustical systems like buildings, bridges and aircrafts …etc. s.e.a as a tool can be applied to the resonant systems in the circumstances of high frequency or/and complex structure». the parameters of s.e.a such as coupling loss factor, internal loss factor, modal density and input power are clarified in this work ; coupled plate sub-systems and explanations are presented for these parameters. the developed system is assumed to be resonant, conservative, linear and there is an equipartition of energy between all the resonant modes within a given frequency band in a given subsystem. the aim of this work is to find the energy stored in the sub-systems for two coupled (welded) plates in rectangular angle systems and study the effect of changing sub-systems dimensions, the results shows that as surface area of directly driven plates a1 increases energy level of plate 1 increases while a reduction in the energy level of indirectly driven plate (plate 2) is noticed. this is because of the strength of coupling decreases towards the weak coupling condition and this leads to a reduction in the power transferred from plate 1 to plate 2 and consequently a lower energy level for plate 2. in addition the effect of changing the internal loss factor for a range of (0.00001-0.1) causes a reduction of the values of energy level in these sub-systems. because the increasing of internal loss factor values led to the increasing of the material resistance and that will dissipate the energy flow across those sub-systems. a comparison is made between s.e.a models built by fortran program and finite element model solved by ansys package. keywords: type i diabetes, backstepping, bergman’s model, oral glucose tolerance test. 1. introduction of the techniques used to predict vibration levels in mechanical structures, are those based on the assumption of idealized mathematical in which the properties of the structures and the excitation are known exactly, and proceed effectively by numerical solutions of the equations of motion. for many structures, however the very detailed physical properties required such a model may not be available, or relevant, for the particular problem at hand. the vibrational behavior of complex structures involves modes high up in the modal series at frequencies of practical interest, and is very sensitive to structural detail. variations of detail between a structure and its mathematical model, or between different realizations of nominally the same structures, may then account for significant quantitative differences in response. the computational effort involved in direct numerical solution may also be prohibitively large for these structures. under these circumstances, a more appropriate technique is often one which provides an understanding of broad features of the vibration levels and transmission, given only a relative coarse and uncertain description of the structure and its excitation. such technique is statistical energy analysis (s.e.a) ref.[1] and ref.[4]. the method statistical energy analysis (s.e.a) involves the division of a complex system into a number of inter-connected sub-systems with similar characteristics, for example plates, beams, acoustic spaces etc. it is based on power flow between sub-systems, the power dissipative by damping and the excitation power input within the system of interest ref.[9]. adnan d. mohammed al-khwarizmi engineering journal, vol. 7, no. 4, pp 41 53 (2011) 42 in this paper, the energy stored in sub-systems is found by using statistical energy analysis, and a comparison is made between analytical solution by using statistical energy analysis (s.e.a) and numerical analysis by using finite element method (f.e.m) built by (ansys 5.4) . for the case of the two coupled (welded) plates joined along a straight edge, one of the plates is excited and that excitation is harmonic at radian frequency ω and of constant amplitude fo. the statistical energy analysis gives us the energy in average manner over all the points of the plate and does not give any information about concentration of energy in particular parts of the sub-systems. the finite element method gives the response in any particular point. therefore, the ansys model is built with an application of point harmonic force at different locations on the driven sub-system. results of the response (energy levels), for a given force location, are predicted at several locations on coupled sub-systems. an average of response at different locations that ensemble averages over the different force locations is obtained. 2. s.e.a theory in an energy distribution model the subsystem energies and input powers are related by the following matrix equation, { } [ ]{ }eap in ω= …(1) equation (1) gives the relationship between the power injected matrix{ }inp , and the total energy matrix at center frequency of the band{ }e , noticing that, [ ]a is a matrix of energy influence coefficients in the relevant frequency band and the symbol (─) indicates time average quantity. in s.e.a a power balance equation is written for each sub-system, so that, for sub-system i, ijtransidissiin ppp ,,, += … (2) the power balance equation means that the input power into sub-system i equals to the summation of power dissipated due to damping in sub-system i, idissp , and the power transmitted from sub-systems i to sub-system j, ijtransp , , due to coupling loss factor between sub-systems. the equation for the dissipation of power in a subsystem can be written as ref. [5] ׃­ iiidiss ep ωη=, … (3) where, iη is the damping loss factor of subsystem i, ie represents the total stored energy in sub-system i and ω is the center frequency of the band of interest. the equation for the net power transmitted from sub-systems i to j is׃­ jjiiijijtrans eep ωηωη −=, … (4) where, ijη , jiη is the coupling loss factor from sub-systems i to j and from sub-systems j to i respectively and it depends on the type of connection between sub-systems, the material properties, the dimensions of the system and the center frequency of the band, ω (rad/sec) ref. [5]. the power flow relationship of a structure consisting of two sub-systems is shown in fig.(1). fig. 1.basic s.e.a model ref.[ 3]. where 1e and 2e are the total stored energy of sub-systems (1) and (2) respectively, inp is the power injected into the first sub-system, dissp ,1 and dissp ,2 are the power dissipated in subsystems due to internal damping and 12p and 21p are the power transmitted between sub-systems. the equation for the power flows between the sub-systems 1 and 2 under typical conditions is expressed as follows ref. [3] ׃ ­ ( ) ( )221112111 eeepin ηηωωη −+= ( ) ( )112221222 eeepin ηηωωη −+= …(5) so the coupling loss factors must be related by the consistency relation ref. (5), jijiji nn ηη = …(6) 1e 2e diss,1p diss,2p 12p 21p ( )2inp ( )1inp adnan d. mohammed al-khwarizmi engineering journal, vol. 7, no. 4, pp 41 53 (2011) 43 where in and jn are the modal densities of subsystems i and j respectively. so, the equation of input power injected into sub-systems can be written as ref. [10]: ( )         −+= 2 2 1 1 112111 n e n eneinp ωηωη ( )       −+= 1 1 2 2 221222 n e n enep in ωηωη …(7) a frequently encountered situation is when one sub-system is directly driven by an external force and the other sub-system is driven only through the coupling. the equation then reduced to ref. (10), ( )       −+= 2 2 1 1 112111 n e n enep in ωηωη       −+= 1 1 2 2 221220 n e n ene ωηωη …(8) equation (7) and (8) for the two sub-system results cannot be extended to more than two subsystems, although the power flow energy difference relationship is true even when the two sub-systems are connected through a third un damped sub-system ref. [11]. by expanding our way of thinking in the previous section, it is possible to formalize, in the same way, the power flow relationships of a structure consisting of multiple sub-systems as shown in fig. (2). fig. 2. three coupled sub-systems ref[11]. the power flow equation for a structure made up of n sub-systems is expressed with the following equation in matrix form,               =                 ×                             +− −      +− −−      + ∑ ∑ ∑ − ≠ ≠ ≠ in i i n n n n ni ninnn n n i n n i i p p p n e n e n e nn nnn nnn mm ll momm l l 2 1 2 2 1 1 1 1 222 2 212221 111121 1 11 ηηη ηηηη ηηηη ω …(9) where i i n e is the energy density of sub-system i. equation (9) represents a set of n-simultaneous linear equations with the independence variable of interest i i n e . this set of equations (matrix equation) can be solved to obtain the stored energies in the coupled sub-systems ref. [3]. e1 e2 e3 13p 12p 23p ( )2inp ( )3inp diss,3p ( )1inp diss,1p diss,2p 21p 32p 31p adnan d. mohammed al-khwarizmi engineering journal, vol. 7, no. 4, pp 41 53 (2011) 44 3. system modeling and s.e.a parameters sea models are all based on the balance of energy and power among groups of natural modes in a system. complex systems can be modeled as coupled mode groups. there are three main steps in defining an sea model. the first is to divide the system into groups of components with similar characteristics, for example plates, beams, acoustic spaces and etc. similar subsystems are used because they have similar modes, similar structures also carry similar wave types like compression, shear and bending for example, a beam has the main mode of bending, as do all other beams. the second step is to define the physical connection between the subsystems for example line connection, bolt connection or weld connection. the last step is to determine or define the external excitation of the system like the noise or vibration generated by wind, engine, transmission, tire ...etc. the parameters that define the sub-systems are the average frequency spacing between modes (center frequency of third octave band), the average modal damping factor can be taken from table (1) that shows some typical values of structural loss factor for some common materials presented by ref. [8], and ref. [6]. the modal density of flat plate in flexural vibration is given by ref.(3): ( ) tc an lπ ω 2 12 = …(10) where; )1( 2υρ − υ =lc …(11) where, lc is the longitudinal wave speed, y is young's modulus, υ is poisson's ratio, a is the surface area of plate, and, t is the plate thickness. the time average input power can be written as, { }12 ~re~ 2 1 −= min zfp …(12) the real part of drive–point mechanical impedance of an infinite plate of thickness t and mass per unit area ρa in flexural vibration ref. [6], is: { } ( )2 3 112 8~re υ ρ − υ= a m tz …(13) and the coupling loss factor between mode groups for line junction is evaluated by lyons and cremer et al., and it is conveniently given in terms of the wave transmission coefficient, 12τ (the ratio of transmitted power to the incident power) for a l i n e j u n c t i o n , l r e f . [7]. i t i s : 1 12 12 2 a lc b πω τ η = …(14) equation (14) reveals that the coupling loss factor depends on the surface area, 1a and the bending wave speed, bc of the first plate for two connected plates with line junction as a function of center frequency, f ref. [6]. where; tfcc lb 8.1= … (15) table 1, structural loss factor for some common materials ref. [6]. material structural loss factor aluminum 1.0×10-4 brick, concrete 1.5×10-2 cast iron 1.0×10-3 copper 2.0×10-3 glass 1.0×10-3 plaster 5.0×10-3 plywood 1.5×10-2 pvc 0.3×100 sand (dry) 0.02-0.2 steel 1-6×10-4 tin 2.0×10-3 and the normal incidence transmission coefficient for two coupled flat plates at right angles to each other is given in ref. [6]: ( ) { }2 2 1 2 1 12 20 −− += ψψτ …(16) where; 2 5 2 2 3 22 2 5 1 2 3 11 tc tc l l ρ ρψ = …(17) adnan d. mohammed al-khwarizmi engineering journal, vol. 7, no. 4, pp 41 53 (2011) 45 the random incidence transmission coefficient 12τ is approximated by ref. [6]: ( ) x x 24.31 754.201212 + = ττ …(18) where; 2 1 t tx = …(19) these parameters must be modeled correctly because they are the coupling of the sub-systems that determines how much energy is transmitted from one subsystem to another. when all these steps are defined correctly and submitted into the major equation of s.e.a eq(9), the conclusion will be easy to estimate when we find the energy stored in each sub-system. it should be noticed that the results of vibrational energies are obtained in decibels (db) rather than any other physical units because it can show any small variation in the energy level and also it can mark the sensitivity of the model quite easily. this is done by using the formula ref. [2],      = refe mnelogdbe ).(10)( 10 …(20) where refe =10e-7 n.m the above equations give the most desired results of statistical energy analysis (s.e.a) model. 4. system details the system considered here is shown in fig. (3). it comprises two thin, flat, uniform, plates joined along a straight edge, each plate is forming one subsystem. the "thin" assumption implies that the effects of shear deformation and rotational inertia are both negligible. the length of the coupling is l and the areas of the plates are a1 and a2. it is assumed that only plate 1 is excited and that the excitation is harmonic at frequency ω and of constant amplitude fo. and the material of the system is steel. the developed system is assumed to be resonant, conservative, linear and there is an equpartition of energy between all the resonant modes within a given frequency band in a given sub-system. fig. 3. two coupled plates system. a1 a2 b1 b2 a t2 t1 line junction (welded) a = 0.3 m b1= 0.4 m b2= 0.2 m t1= 0.003m t2= 0.002m a1= 0.12m2 a2= 0.06m2 ρ = 7800 kg/m3 υ = 0.3 y=2×1011n/m2 η1= η2= 0.0001 fo=1n y z x foejωt driven plat adnan d. mohammed al-khwarizmi engineering journal, vol. 7, no. 4, pp 41 53 (2011) 46 5. finite element modeling in this paper, the energy stored in sub-systems is found by using statistical energy analysis, and a comparison is made between analytical solution (s.e.a) and numerical analysis (f.e.m) ,built by ansys 5.4 for the case of the two coupled (welded) plates. because, the statistical energy analysis gives us the energy in average manner over all the points of the plate and does not give any information about concentration of energy in particular parts of the sub-systems and that the finite element method gives the response in any particular point. therefore, the loading of harmonic forces will apply at different points on the first plate (five different points) and the average responses over different locations (ten different points for each plate) are obtained. a job name and analysis title is specified from the file option on the utility menu and clarifies the type of analysis (structural analysis). then, prep7 preprocess is used to define the element types, element real constant, material properties for steel after consider it as isotropic material, and the model geometry as shown in figure (4). their properties will be: element type = shell elastic. young modulus of elasticity, y=2×1011 (n/m2). poisson's ratio, υ=0.3. mass density, ρ=7800 (kg/m3). fig. .4.a tested model of two coupled plates built by ansys package. in applying the finite element method, it is necessary to divide the structure into a set of interconnected elements sufficiently small to adequately model, the structural geometry and to adequate represent loads and structural deformations. so, the whole system was divided and meshed (free mesh) as follows: time of the run of program= 105 minutes. number of elements for the first sub-system (plate 1)=192. number of elements for the second sub-system (plate 2)=96. figure (5) shows the final model after it is meshed and the load is applied to it, and by that the model building is completed. fig. .5. the final model built by ansys 5.4. 6. s.e.a results and discussion 6.1. the general behavior of energy flow the trend of all energy versus frequency curves is similar for all cases studied in this work. as the center frequency of third octave band increases the energy content of all sub-systems decreases. an obvious explanation for this behavior is due to the fact that as frequency increases the amplitude of vibration of any structural members decreases and consequently a reduction in the level is observed. 6.2. effect of variation of surface area on energy level figures (6) and (7) demonstrate the effect of variations of the surface area of the directly driven plate a1 on the energy levels of the coupled plateplate system. the figures display the variation as a function of center frequency of 1/3 octave bands. it shows that as a1 increases energy level of plate 1 increases while a reduction in the energy level of the indirectly driven plate is noticed. this is because of the fact that as a1 increases the adnan d. mohammed al-khwarizmi engineering journal, vol. 7, no. 4, pp 41 53 (2011) 47 strength of coupling decreases towards the weak coupling condition. this leads to a reduction in the power transferred from plate 1 to plate 2 and consequently a lower energy level for plate 2. figures (8) and (9) show that as the surface area of the indirectly driven plate a2 increases its energy level increases and a reduction in energy level of the directly driven plate is noticed. this is due to the same reason described above (i.e.: coupling strength). table (2) displays some of the predicted results at 500 hz center of frequency of 1/3 octave band. 101 102 103 104 105 ceterfreqencyof1/3octaveband(hz) 0 5 10 15 20 25 30 35 40 45 50 55 60 en er gy le ve l, e1 (d b) a1=0.06m2 a1=0.12m2 a1=0.18m2 a1=0.24m2 a1=0.30m2 case 1 plate-plate system fig. .6. the effect of variation of surface area of directly driven plate on first plate energy levels. 101 102 103 104 105 ceter freqencyof1/3 octave band(hz) 0 5 10 15 20 25 30 35 40 45 50 55 60 en er gy le ve l, e2 (d b) a1=0.06 m2 a1=0.12 m2 a1=0.18 m2 a1=0.24 m2 a1=0.30 m2 case 1 plate-plate system fig. 7. the effect of variation of surface area of directly driven plate on second plate energy levels. 101 102 103 104 105 ceterfreqencyof1/3octaveband(hz) 0 5 10 15 20 25 30 35 40 45 50 55 60 en er gy le ve l, e1 (d b) a2=0.06m2 a2=0.12m2 a2=0.18m2 a2=0.24m2 a2=0.30m2 case1 plate-platesystem fig. 8.the effect of variation of surface area of indirectly driven plate on first plate energy levels. 101 102 103 104 105 ceterfreqencyof1/3octave band(hz) 0 5 10 15 20 25 30 35 40 45 50 55 60 en er gy le ve l, e2 (d b) a2=0.06 m2 a2=0.12 m2 a2=0.18 m2 a2=0.24 m2 a2=0.30 m2 case1 plate-plate system fig. 9 the effect of variation of surface area of indirectly driven plate on second plate energy levels. plate-plate system plate-plate system plate-plate system plate-plate system center frequency of 1/3octave band (hz) center frequency of 1/3octave band (hz) center frequency of 1/3octave band (hz) center frequency of 1/3octave band (hz) adnan d. mohammed al-khwarizmi engineering journal, vol. 7, no. 4, pp 41 53 (2011) 48 table 2, effect of surface area variation on the energy level at 500 hz. values of area m2 0.06 0.09 0.12 0.15 0.18 δa1 e1 28.701640 30.247600 30.915370 31.292170 31.535020 e2 30.444710 28.980370 27.887220 27.014640 26.288390 δa2 e1 30.247600 28.712280 27.588370 26.702860 25.973140 e2 28.980370 30.437570 31.056880 31.403130 31.624950 6.3. effect of variation of internal (damping) loss factor on energy level the second part of the parametric study is concerned with the effect of variation of material dissipation loss factor on the predicted results of total vibrational energy for case studied in this work. this is done by increasing (alternatively) the dissipation loss factor (ηi) of one sub-system in each case while other parameters kept fixed. figures (10)-(13) present the effect of variation of internal loss factor for a range of (0.00001-0.1). this variation causes a reduction of the values of the energy levels for the two plates and that is because the increasing of internal loss factor values led to increasing of the material resistance and that will dissipate the energy flow across that sub-system. of course the amount of the energy dissipated depends on the sub-system that the variation lies on. table (3) displays some of the predicted results at 500 hz center of frequency of 1/3 octave band. 101 102 103 104 105 ceterfreqencyof1/3octaveband(hz) -10 -5 0 5 10 15 20 25 30 35 40 45 50 55 60 en er gy le ve l, e1 (d b) ilf1=0.00001 ilf1=0.0001 ilf1=0.001 ilf1=0.01 ilf1=0.1 case1 plate-platesystem fig. 10. the effect of variation of directly driven plate internal loss factor on the plate 1 energy levels. 101 102 103 104 105 ceterfreqencyof1/3octaveband(hz) -20 -15 -10 -5 0 5 10 15 20 25 30 35 40 45 50 55 60 en er gy le ve l, e2 (d b) ilf1=0.00001 ilf1=0.0001 ilf1=0.001 ilf1=0.01 ilf1=0.1 case1 plate-platesystem fig. 11. the effect of variation of directly driven plate internal loss factor on the plate 2 energy levels. plate-plate system center frequency of 1/3octave band (hz) plate-plate system center frequency of 1/3octave band (hz) adnan d. mohammed al-khwarizmi engineering journal, vol. 7, no. 4, pp 41 53 (2011) 49 101 102 103 104 105 ceterfreqencyof1/3octaveband(hz) 0 5 10 15 20 25 30 35 40 45 50 55 60 en er gy le ve l, e1 (d b) ilf1=0.00001 ilf1=0.0001 ilf1=0.001 ilf1=0.01 ilf1=0.1 case1 plate-platesystem fig. 12. the effect of variation of indirectly driven plate internal loss factor on the plate 1 energy levels. 101 102 103 104 105 ceterfreqencyof1/3octaveband(hz) -15 -10 -5 0 5 10 15 20 25 30 35 40 45 50 55 60 en er gy le ve l, e2 (d b) ilf1=0.00001 ilf1=0.0001 ilf1=0.001 ilf1=0.01 ilf1=0.1 case1 plate-platesystem fig. 13. the effect of variation of indirectly driven plate internal loss factor on the plate 2 energy levels. table 3, effect of dissipated loss factor variation on the energy level at 500 hz. values of internal loss factor 0.00001 0.0001 0.001 0.01 0.1 δη1 e1 15.409160 15.336340 14.668310 10.819890 2.445565 e2 12.662200 12.589380 11.921350 8.072927 -0.301393 δη2 e1 12.667110 12.638050 12.368280 10.819890 8.751205 e2 11.415940 11.370820 10.943660 8.072927 0.411249 6.4. comparison between s.e.a and f.e.m results figures (14)-(18) present the average of energy levels predicted by statistical energy analysis and finite element averages over different response locations due to an applied load at a specific location (node). figure (19) shows the comparison between the average energy levels predicted using s.e.a and the ensemble averages of energy levels over the different force and response locations using f.e.m. the noticed differences between results of the two methods are due to the fact that s.e.a obtains the response for the whole sub-system without going into the details of the modes of vibration involved while f.e.m results involve mode by mode calculations. the comparison shows that at high frequency domain the results of the two methods become more comparable because of the fact that at high frequency regimes the number of modes becomes higher than that at low frequency regimes. the higher the number of modes means that the coupled sub-system in that region of frequency has high modal overlap factor which is the condition that should be available when using s.e.a. this comparison proved that statistical energy analysis is more acceptable tool of analysis at high frequencies than that at low frequencies. ilf2=0.00001 ilf2=0.0001 ilf2=0.001 ilf2=0.01 ilf2=0.1 center frequency of 1/3octave band (hz) plate-plate system center frequency of 1/3octave band (hz) ilf2=0.00001 ilf2=0.0001 ilf2=0.001 ilf2=0.01 ilf2=0.1 plate-plate system adnan d. mohammed al-khwarizmi engineering journal, vol. 7, no. 4, pp 41 53 (2011) 50 101 102 103 104 105 centerfreqencyof1/3octaveband(hz) -20 -15 -10 -5 0 5 10 15 20 25 30 35 40 45 50 55 60 en er gy le ve l, e1 ,e 2 (d b) e1, sea e2, sea e1, fem e2, fem fig.14. the comparison between s.e.a results and f.e.m average results due to a load applied in the center point of the first sub-system. 101 102 103 104 105 centerfreqencyof1/3octaveband(hz) -20 -15 -10 -5 0 5 10 15 20 25 30 35 40 45 50 55 60 en er gy le ve l, e1 ,e 2 (d b) e1, sea e2, sea e1, fem e2, fem fig. 15. the comparison between s.e.a results and f.e.m average results due to a load applied in the upper right corner of the first sub-system. 101 102 103 104 105 centerfreqencyof1/3octaveband(hz) -15 -10 -5 0 5 10 15 20 25 30 35 40 45 50 55 60 en er gy le ve l, e1 ,e 2 (d b) e1,sea e2,sea e1,fem e2,fem fig.16. the comparison between s.e.a results and f.e.m average results due to a load applied in the upper left corner of the first sub-system. 101 102 103 104 105 centerfreqencyof1/3octaveband(hz) -20 -15 -10 -5 0 5 10 15 20 25 30 35 40 45 50 55 60 en er gy le ve l, e1 ,e 2 (d b) e1,sea e2,sea e1,fem e2,fem fig. 17. the comparison between s.e.a results and f.e.m average results due to a load applied in the lower right corner of the first sub-system. center frequency of 1/3octave band (hz) center frequency of 1/3octave band (hz) center frequency of 1/3octave band (hz) center frequency of 1/3octave band (hz) adnan d. mohammed al-khwarizmi engineering journal, vol. 7, no. 4, pp 41 53 (2011) 51 101 102 103 104 105 centerfreqencyof1/3octave band(hz) -20 -15 -10 -5 0 5 10 15 20 25 30 35 40 45 50 55 60 en er gy le ve l, e1 ,e 2 (d b) e1, sea e2, sea e1, fem e2, fem fig.18. the comparison between s.e.a results and f.e.m average results due to a load applied in the lower left corner in the first sub-system. 101 102 103 104 105 centerfreqencyof1/3octave band(hz) -15 -10 -5 0 5 10 15 20 25 30 35 40 45 50 55 60 en er gy le ve l, e1 ,e 2 (d b) e1, sea e2, sea e1, fem e2, fem fig. 19. the comparison between s.e.a results and f.e.m ensemble average. table 4, the values of energy at frequencies of octave band for s.e.a and f.e. frequency hz 1000 2000 4000 8000 16000 s.e.a e1 27.240470 24.234590 21.230570 18.229050 15.231060 e2 25.965870 22.949580 19.930900 16.908710 13.881680 f.e.m e1 28.000000 23.200000 26.100000 9.9900000 2.6500000 e2 16.800000 10.600000 12.400000 7.4100000 1.7300000 7. conclusions the main conclusions drawn from this work based on the results obtained in the present study are summarized as follows: 1. statistical energy analysis is a quite powerful tool in analyzing the dynamic behavior of coupled systems without going into great technical details as other approaches. 2. the main thing to remember is that statistical energy analysis uses power flow from higher sub-system energy to lower sub-system energy for the basis of its calculations. it is also important to remember that all of the parameters are based on averages and that; this method cannot calculate an exact response at an exact location. 3. the general trends of all energy reverse frequencies decrease with increasing frequency. this behavior is due to the fact that by increasing frequency, the amplitude decreases and consequently causes a reduction in energy levels. 4. the energy flow between sub-systems is increased by increasing the coupling loss factor (strong coupling). while decreasing the coupling loss factor decreases the energy flow between sub-systems (weak coupling). 5. changing of sub-system dimensions affects the coupling loss factor and modal density and adnan d. mohammed al-khwarizmi engineering journal, vol. 7, no. 4, pp 41 53 (2011) 52 consequently affects the energy stored in that sub-system. 6. the energy stored in particular sub-system decreases with increasing the internal loss factor. 7. the suggested analytical solution gives good agreement with the numerical solution at the high frequency domain. 8. references [1] cotonis v., langley r.s. and kinder m. r. f., (2005), "numerical and experimental validation of variance prediction in the s.e.a of built-up system", journal of sound and vibration, vol. 288, pp. 701-728. [2] fahys f.j., and mohammed a.d., (1996), "a study of uncertainty in application of s.e.a to coupled beam and plate system, part i: computational example", journal of sound and vibration, vol. 158, pp. 45-67. [3] koizumis t., tsujiuchi n., tanaka h., okubo m. and shinomiya m., (1992), "prediction of the vibration in buildings using s.e.a", journal of sound and vibration. [4] lyons r. h., (1975), "sea of dynamical systems: theory and application", mit press, cambridge ma. [5] maces b., (2003), "s.e.a, energy distribution models and system modes", journal of sound and vibration, vol. 264, pp. 391-409. [6] nortons m. p., (1989), "fundamental of noise and vibration analysis for engineers", cambridge university press, new york, port chester melbourne sydney. [7] parks w. s., thompson d. j. and ferguson n. s., (2005), "variability of the coupling loss factor between coupled plates", journal of sound and vibration, vol. 279, pp. 557-579. [8] rankys m. f. and clarkson b. l., (1983), "frequency average loss factor of plates and shells", journal of sound and vibration, vol. 89, no. 3, pp. 309-323. [9] renjis k., (2004), "estimation of spectral density using s.e.a", journal of sound and vibration, 9vol. 275, pp. 447-451. [10] westers e. c. n. and mace b., (2005), "s.e.a of two edge – coupled rectangular plates:ensemble average", journal of sound and vibration, vol. 193, no. 4, pp. 793822. [11] whites r. g. and walker j. g., (1982), "noise and vibration", chichester harwood ltd. )2011( 41 – 53 ، صفحة4، العدد 7مجلة الخوارزمي الھندسیة المجلد عدنان داوود محمد 53 باستعمال طریقة تحلیل الطاقة اإلحصائي) ملحومة(تقدیر طاقة االھتزاز لصفیحتین متصلتین حوراء صفاء إبراھیم حمد عدنان داوود م الجامعة التكنولوجیة /قسم ھندسة السیطرة والنظم الخالصة , صائي والتي یمكن تطبیقھا على المنظومات المھتزة المیكانیكیة والصوتیة مث ل البنای ات ھذا البحث یتعامل مع طریقة تسمى طریقة تحلیل الطاقة اإلح العوام ل الت ي تعتم د ). او ھیك ل معق د / عالي أو اتردد(ھذه الطریقة كأداة یمكن تطبیقھا على المنظومات الخاضعة للظروف . الخ.....والطائرات, الجسور الكثافة الطوریة والقدرة الداخلة إلى النظام المھتز تم توضیحھا لصفیحتین متصلتین , معامل الخسارة الداخلي, طمعامل خسارة االرتبا(علیھا ھذه الطریقة ق دیمھا ف ي ھ ذا وتم تقدیم شرح لھذه العوامل في ھذا البحث و باإلضافة إلى ذلك الشروط والخطوات التي یجب أتباعھا للنمذجة باستخدام ھذه الطریق ة ت م ت و األھتزاز یتم بصورة خطیة و ھناك توزیع متساوي للطاقة بین كل , و یتم حفظ الطاقة فیھا, مة المھتزة تم أفتراض أنھا تھتز بصورة رنانةالمنظو. البحث قائم ة بزاوی ة ) ملحوم ة (الھدف من ھذا البحث ھ و أیج اد الطاق ة المخزون ة ف ي األج زاء المھت زة الص فیحتیین م رتبطتین . األجزاء المھتزة عند تردد معین ) الص فیحة األول ى (النتائج تبین أن عند زیادة المساحة السطحیة للصفیحة المثارة بطریقة مباش رة , ھذه األجزاء) طول وعرض(ودراسة تأثیر تغییر أبعاد ھ ذا بس بب أن ق وة األتص ال ب ین و). الص فیحة الثانی ة (یزید مستوى الطاقة للصفیحة األولى بینما یقل مستوى الطاقة للصفیحة التي لم تثار بطریقة مباشرة اقة قلی ل للص فیحة الصفیحتین یتجھ نحو األرتباط الضعیف و ھذا یقود الى قلة الطاقة المنتقلة من الصفیحة األولى الى الصفیحة الثانیة و بالتالي مستوى ط التغییر یسبب في قلة مستوى الطاق ة للص فیحتیین و ذل ك ھذا ) ٠,١-٠,٠٠٠٠١(باإلضافة إلى ذلك دراسة تغییر معامل الخسارة الداخلي لمدى من . الثانیة وتم عمل مقارنة بین طریقة . بسبب أن زیادة معامل الخسارة الداخلي یؤدي الى زیادة المقاومة الداخلیة للمادة و ھذا سیضیع الطاقة المنتقلة بین الصفیحتیین ansysفورتران وطریقة العناصر المحددة التي تم عمل نموذج لھل باستخدام برنامج تحلیل الطاقة اإلحصائي التي تم بناء نموذج لھا باستعمال برنامج .5.4 )2011( 41 – 53 ، صفحة4، العدد 7مجلة الخوارزمي الھندسیة المجلد عدنان داوود محمد رمزي وعلى وزينب al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 10, no. 2, p.p. 1522 (2014) drag-reducing agent for aqueous liquid flowing in turbulent mode through pipelines ali m. hameed* ramzy s. hamied** zainab y. shnain*** *,*** department of chemical engineering / university of technology ** department of petroleum technology / university of technology *e-mail: alialjanabe@yahoo.com **e-mail: ramze_eng@yahoo.com ***e-mail: za.yosif@yahoo.com (received 18 june 2013; accepted 15 april 2014) abstract in this study, mucilage was extracted from malabar spinach and tested for drag-reducing properties in aqueous liquids flowing through pipelines. friction produced by liquids flowing in turbulent mode through pipelines increase power consumption. drag-reducing agents (dra) such as polymers, suspended solids and surfactants are used to reduce power losses. there is a demand for natural, biodegradable dra and mucilage is emerging as an attractive alternative to conventional dras. literature review revealed that very little research has been done on the dragreducing properties of this mucilage and there is an opportunity to explore the potential applications of mucilage from malabar spinach. an experimental piping rig was used to study the dr properties of the mucilage on water under the effect of varying pipe dimensions and mucilage concentrations. it is shown that these additives can dramatically reduce friction drag provided that the flow is occurring under turbulent conditions. experimental results also show that dr increases when the mucilage concentration increases. keywords: drag reduction, turbulent flow, friction reduce, additives, pipeline, eddies 1. introduction drag reduction (dr) is a significant area of interest in the transportation of fluids via pipelines, which is a crucial component of the chemical industry. fluids flowing in turbulent mode commonly experience a drag, indicated by the pressure drop between two points. the drag phenomenon is unavoidable and pumping systems utilized to reduce pressure drop constitute 20% of the world’s electricity demand (chanson and qiao,, 2001). drag-reducing agents (dra) have been formulated as a cheaper alternative to pumping systems, such as polymers, suspended solids, and surfactants. mucilage, a compound found in plants, has been proven to have drag-reducing properties, and it is an attractive alternative because it is easily procured and is biodegradable. drag reduction is the phenomenon of effectively reducing the friction factor of a flowing fluid by using a small amount of additives, named drag-reducing agents (dra). brostow, (2008) described dr as a phenomenon that occurs when an additive put into the fluid increases the average flow velocity. the mechanism of dr is still unknown. different postulates to be placed forward to explain the dr mechanisms for different dra. the drag-reducing properties of suspended solids are not as extensively researched as polymers, but they are favored because they can be added (and removed) to ( and from) the liquid easily, and they are mechanically stable. there are two main types of suspended solids used; granular/spherical particles and fibers. when the mailto:alialjanabe@yahoo.com mailto:ramze_eng@yahoo.com mailto:za.yosif@yahoo.com ali m. hameed al-khwarizmi engineering journal, vol. 10, no. 2, p.p. 1522 (2014) 16 concentration of suspended solids increases the drag reduction also increases (deverich, et al., 1985). surfactants reduce surface tension of a liquid and are usually organic compounds. surfactant molecules aggregate at a critical concentration value, forming micelles (truong, 2001). surfactants display better drag-reducing properties at lower velocity gradients because the micelles disintegrate at higher velocity gradients. mucilage is a naturally-occurring polysaccharide in plants and in some microorganisms. mucilage swells up to form a viscous, gel-like liquid when added to water. examples of plants containing mucilage are cacti, flaxseeds, okra, fenugreek seeds, aloe vera and psyllium seeds. in 1990, decho discovered that microorganisms living on “fluff”, a layer of organic aggregates produced from bio deposits of oysters, secrete mucilage to stabilize fluff against water turbulence. the mucilage secreted reduces surface tension at the interface between fluff and water, creating less turbulent water at the interface. mucilage derived from okra has proven to reduce drag in water up to 58% (rosli et.al, 2009). the same study also observed that the percentage drag reduction increases when the length-to-diameter ratio, l/d increases. okra mucilage shows effective drag-reducing properties when water flows in turbulent mode through the pipeline. malabar spinach (basella, 2009) is a perennial vine found in the tropics and is used in chinese cuisine. the stem is very mucilaginous, and it is a very rich source of soluble fiber. the malabar spinach is sometimes used to thicken soups due to the rich content of mucilage. the plant grows well in a variety of soils, with little dependence on soil fertility. the plant is easily cultivated and can be grown from either seeds or cuttings. in 2009, stephens, concluded that even stems, which are too tough to eat can be put back into the soil and re-rooted. malabar spinach is easily available at local markets and at a very affordable price. the stems are typically uneaten and this does not diminish the demand for malabar spinach as food. the price for 250g of malabar spinach (leaves included) is 0.42$. the leaves contain little to no mucilage. 2. experimental procedure 2.1. preparation of mucilage malabar spinach was obtained from malaysia. the stems are separated from the leaves and cleaned. the stems are then chopped into fine pieces until a semi-solid paste is formed. the paste is then mixed with water in the ratio of 100g of paste to 200ml of water. the mixture was allowed to stand in room temperature for approximately 24 hours, after which the mucilage is strained from the solids by filtering the mixture through a fine muslin cloth (diameter). 2.2. operation of piping apparatus the experiment was carried out in a piping apparatus as shown in figure 1. tank 1 is filled with water until a volume of 420l is achieved. the mucilage concentrations tested are 0ppm, 100ppm, 300ppm, 500ppm, 700ppm and 1000ppm. the mucilage concentration in ppm, [m] is calculated using the equation (1): [m] = x 106 …(1) the mucilage is added into tank a while water is added to ensure a well-mixed solution. the solution is then allowed to circulate throughout the system. water entering tank b is recycled back to tank b by the pump b. there are three testing pipes: pipe a with internal diameter 0.0381m, pipe b with internal diameter 0.0254m, and pipe c with internal diameter 0.0127m. for this study, only pipe b was utilized. flow rate of water circulating in the apparatus, q, is measured using a non-invasive, ultrasonic portable flow meter. the flow meter used is ultra flux minisonic ® p which is clamped on the tested pipe. pressure drop readings are taken using a barometer across four different pipe lengths; 0.5m, 1.0m, 1.5m and 2.0m. the readings are taken once q is relatively constant. ali m. hameed al-khwarizmi engineering journal, vol. 10, no. 2, p.p. 1522 (2014) 17 fig. 1. experimental rig. 2.3. determination of drag reduction at a fixed flow rate, the pressure drop values taken when mucilage concentration is 0ppm are denoted ∆po. the pressure drop values taken at other concentrations and at the same flow rate are denoted ∆pi. percent drag reduction, %dr, is calculated using the equation (2): dr = ( ) x 100% …(2) we assumed temperature of the water to be 25°c. reynolds numbers, re is calculated using the equation (3): re = …(3) where v = in m/s graphs are plotted to see the effect of reynolds number, mucilage concentration and pipe length on drag reduction. 3. results and discussion 3.1. effect of reynolds number on dr in figures.(1 to 6) the percent drag reduction is plotted against reynolds number for different pipe lengths in pipe b (d=0.00254m)., we observed that the %dr increases when re increases but then decreases after a certain re value. this is possibly due to increased shear stresses that eventually overwhelm the dr properties of the mucilage. the mucilage structure is said to undergo mechanical degradation and is unable to function as a dra after that certain re value from this figure, clearly we can see that an increasing of additive concentration can give great impact to the performance of percentage drag reduction. ali m. hameed al-khwarizmi engineering journal, vol. 10, no. 2, p.p. 1522 (2014) 18 fig. 2. effect of reynolds number on %dr at mucilage concentration of 100ppm. fig. 3. effect of reynolds number on %dr at mucilage concentration of 300ppm. fig. 4. effect of reynolds number on %dr at mucilage concentration of 500ppm. fig. 5. effect of reynolds number on %dr at mucilage concentration of 700ppm. fig. 6. effect of reynolds number on %dr at mucilage concentration of 1000ppm. 3.2. effect of pipe length on dr in figures (8 to 12) the percent drag reduction is plotted against pipe length for different reynolds numbers. we observed that %dr increases with pipe length than either become constant or decrease. a possible reason for this behavior is the formation of laminar regions and turbulent slugs within the pipe, as described by figure. 7 below: ali m. hameed al-khwarizmi engineering journal, vol. 10, no. 2, p.p. 1522 (2014) 19 fig. 7. formation of laminar regions and turbulent slugs within the pipeline. davidson, (2006) described that initiation of turbulence begins at the pipe inlet. the turbulent patches grow and merge to establish fully developed turbulence. however, this turbulence is intermittent, being interspersed by quiescent, laminar regions. this description can explain the volatility in dr data across different pipe lengths as the turbulent regions within the pipe are interspersed with laminar regions, affecting the dr properties of the mucilage in these regions. fig. 8. effect of pipe length on %dr at mucilage concentration of 100ppm. fig. 9. effect of pipe length on %dr at mucilage concentration of 300ppm. fig. 10. effect of pipe length on %dr at mucilage concentration of 500ppm. fig. 11. effect of pipe length on %dr at mucilage concentration of 700ppm. turbulent slug initiation formation of turbulent slug laminar region ali m. hameed al-khwarizmi engineering journal, vol. 10, no. 2, p.p. 1522 (2014) 20 fig. 12. effect of pipe length on %dr at mucilage concentration of 1000ppm. 3.3. effect of mucilage concentration on dr figure.13 represents the variation of %dr with increasing mucilage concentration. generally, when mucilage concentration increases, %dr increases. this is because there are more mucilage components to interact with the fluid flow and to increase the occurrence of dr. it is observed that, by adding a low concentration of the additives, one can find a reduced pressure drop per unit length at the same flow conditions. fig. 13. effect of mucilage concentration on %dr. 4. conclusion mucilage from malabar spinach can be used as a dra for aqueous solutions. experimental results show that dr increases when reynolds number increases until a certain value where mechanical degradation occurs and the dr properties of the mucilage are no longer effective. dr also increases when pipe length increases; however inconsistencies in experimental data may be due to the formation of alternating turbulent and laminar regions within the pipe. experimental results also show that dr increases when the mucilage concentration increases. notation a inside pipe area m2 d internal pipe diameter m dr drag reduction dra drag-reducing agents l pipe length (length of testing section) m ppm parts per million q water flow rate m3/s re reynolds number v water velocity m/s greek letters ρ density of water at 25°c kg/m3 µ viscosity of water at 25°c kg/m.s 5. references [1] basella alba. (2009). retrieved august 26, 2009 from http://www.wikipedia.en/basella_alba. [2] brostow, w. (2008), “drag reduction in flow: review of applications, mechanism and prediction”, journal of industrial and engineering chemistry, 14, 409-416. doi:10.1016/j.jiec.2008.07.001 [3] chanson, h., & qiao, g., “drag reduction in hydraulics flow”, brisbane: university of queensland, (1994). [4] davidson, p.a., “turbulence: an introduction for scientists and engineers”, ny: oxford university press, (2006). [5] decho, a. w., “microbial exopolymer secretions in ocean environments: their role(s) in food webs and marine processes”, oceanography and marine biology annual reviews, 28, 78–153, (1990). [6] deverich, i.v., eroshenko, v.m. & zaichik, l.i. (1985). influence of particles on turbulent flow in channels. journal of fluid dynamics, 20, 34-42.retrieved august 24, http://www.wikipedia.en/basella_alba ali m. hameed al-khwarizmi engineering journal, vol. 10, no. 2, p.p. 1522 (2014) 21 2009 from website http://www.springerlink.com/content/x48hux 265785117p/fulltext.pdf [7] graebel, w.p. “advanced fluid mechanics”, ny: elsevier science and technology right departmen oxford, inc, (2007). [8] rosli, m.y., siti, n.k. & hayder a.m.(2007), “okra mucilage as new natural pumping power-saver in aqueous media flow in pipelines”, paper presented at the 3rd international conference on chemical & biochemical engineering, sabah. retrieved august 27, (2009). [9] langenheim, j.h., “plant resins: chemistry, evolution, ecology & ethnobotany”, or: timber press, (2003). [10] stephens, m.j., spinach, malabar – basella rubar l. retrieved august 20, 2009 from http://edis.ifas.ufl.edu/pdffiles/mv/mv138 00.pdf, (2009). [11] truong, v.t., “drag reduction technologies”, firshermans bend vic: dsto aeronautical and maritime research laboratory, (2001). [12] fengchen li, yasuo kawaguchi, bo yu, jin jia wei, koichi hishida, experimental study of drag-reduction mechanism for a dilute surfactant solution flow, international journal of heat and mass transfer 51, 835-843, (2008). [13] lixin cheng, dieter mewes, andrea luke, “boiling phenomena with surfactants and polymeric additives”: a state-of-the-art review, international journal of heat and mass transfer 50, 2744-2771, (2007). [14] d. mowla and a. naderi, “experimental study of drag reduction by a polymeric additive in slug two-phase flow of crude oil and air in horizontal pipes”, chemical engineering science 61, 1549 – 1554, (2006). . http://www.springerlink.com/content/x48hux http://edis.ifas.ufl.edu/pdffiles/mv/mv138 )2014( 1522، صفحة 2، العدد10دجلة الخوارزمي الھندسیة المجلعلي محمد حمید م 22 معامل االعاقة للسوائل التي تتدفق في الوضع المضطرب خالل خطوط االنابیب ***زینب یوسف شنین **رمزي صیھود حمید *علي محمد حمید الجامعة التكنولوجیة/ قسم الھندسة الكیمیاویة *** ،* یةالجامعة التكنولوج/ النفط قسم تكنولوجیا ** alialjanabe@yahoo.com: *البرید االلكتروني ramze_eng@yahoo.com:البرید االلكتروني ** za.yosif@yahoo.com : البرید االلكتروني** * الخالصة . بیبفي ھذه الدراسة تم استخالص الصمغ من السبانخ واختبارھا لغرض دراسة خواص تقلیل االعاقة للسوائل المائیة التي تتدفق خالل خطوط االنا ویستخدم معامل االعاقة مثل . دة في استھالك الطاقةاالحتكاك التي تنتجھا السوائل المتدفقة في الوضع المضطرب من خالل خطوط االنابیب تؤدي الى زیا . ھنالك طلب على المواد الطبیعیة والمواد القابلة للتحلل والصمغیة باعتبارھا بدیال فعاال . المواد الصلبة العالقة والسطحیة للحد من خسائر الطاقة، البولیمرات راسة تقلیل االعاقة للصمغ وكذلك ھنالك فرصة المكانیة استكشاف التطبیقات المحتملة للصمغ كشفت مراجعة االدبیات السابقة بانھ یوجد ابحاث قلیلة حول د .تم استخدام انابیب الحفر التجریبیة لدراسة خصائص الصمغ على المیاه تحت تأثیر ابعاد مختلفة لالنابیب وكذلك تركیز الصمغ. من السبانخ mailto:alialjanabe@yahoo.com mailto:ramze_eng@yahoo.com mailto:za.yosif@yahoo.com حسين جاسم،ظافر صادق،عبد الجبار al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 8, no.3, pp 1-12 (2012) types of the fiber glass-mat on fatigue characteristic of composite materials at constant fiber volume fraction: experimental determination hussain j. al-alkawi* dhafir s. al-fattal** abdul-jabar h. ali*** *department of electromechanical engineering/ university of technology **department of mechanical engineering/ university of technology **the student affairs department and authentication/ university of baghdad (received 4 january 2012; accepted 29 april 2012) abstract the aim of this work is to study the influence of the type of fiber glass –mat on fatigue behavior of composite material which is manufactured from polyester and e-glass (woven roving, chopped strand mat (csm)) as a laminate with a constant fiber volume fraction (vf) of 33%. the results showed that the laminates reinforced with e-glass (woven roving) [0/90, ±45.0/90] and [0/90, csm, 0/90] have lower fatigue strength than the laminates reinforced with e-glass [0/90]3,[csm]3 and [csm, 0/90, csm] although they had different tensile strength; the best laminate was [0/90]3 . keywords: composite material, fatigue, fiber glass mat. 1. introduction composite materials are commonly discontinuous phases embedded in a continuous phase. the discontinuous phase is usually harder and stronger than the continuous phase and is called the reinforcement; whereas the continuous phase is usually softer and is termed the matrix. the matrix holds the reinforcements in an orderly pattern [1]. this work focuses on fiber-reinforced composites composed of fibers embedded in a matrix; the fibers are long, continuous in one or multiple directions. such materials offer advantages over conventional isotropic structural materials such as steel, aluminum and other types of metal. these advantages include high strength, good fatigue strength and corrosion resistance. in addition, by changing the arrangement of the fibers, the properties of the material can be tailored to meet the requirements of a specific design [2]. z. hashin and a. rotem [3] studied the influence of off-axis loading on fatigue strength of fiber glass – epoxy unidirectional composite; fatigue curves are shown for off-axis angles of 0, 5, 10, 30 and 60 degrees. even small off-axis angle of 5 to 10 degree cause a drastic reduction in the fatigue strength compared with 0 degree loading. with the off-axis angle of 60 degrees, the fatigue strength at 105 cycles to failure decreased to about 2.5kg/mm2 from a value of about 80kg/mm2 at 0 degree orientation. wedad al-azzawy[4] studied the fatigue and vibration characteristics of laminated composite shells of revolution. all tests were conducted at room temperature (18-25co).the aim of fatigue test is to determine (s-n) curves of 0, 45, 90 degree under stress ratio r=-1. the s-n curves showed fatigue strength at 106 cycles, of about, 117mpa, 17mpa and 12mpa at 0, 45 and 90 degree orientation respectively. muhannad z. khalifa, et.al [5] studied the fatigue behaviors of composite material manufactured for this paper by stacking four layers of e-glass fiber in different angle orientations [0, ±45, 0/90] degree immersed in polyester resin with total thickness 4mm. the hussain j. al-alkawi al-khwarizmi engineering journal, vol. 8, no.3, pp1 -12 (2012) 2 results showed that failure of laminas at ±45, and, 0/90 degree is due to matrix failure in the direction of fiber, whereas for unidirectional lamina at 0 degree the failure is due to fiber breakages. al-alkawi, et.al [6] studied the influence of temperature on the ultimate tensile strength (uts) of composite material which is manufactured from polyester and e-glass (woven roving, chopped strand mat) as a laminate with a constant fiber volume fraction (vf) of 33%. the results showed a little effect of temperature on tensile strength in the range of room temperature (rt) to 50 oc for laminates reinforced with e-glass (woven roving) [0/90, ±45.0/90], [0/90]3, and [0/90, csm, 0/90], but for laminates reinforced with e-glass chopped strand mat (csm), as [csm] 3 and [csm, 0/90, csm], a continuous reduction in strength was observed with increasing temperature from (rt) to 60 oc. the highest percentage reduction in strength was 23% at 60oc as compared to (rt) for [csm]3 laminate. 2. experimental work 2.1. materials in this work, e-glass fiber which was obtained in the form of discontinuous and continuous woven strand mats is used. it was not possible to measure the glass fiber properties experimentally, hence reasonable values were chosen from the literature. polyester (topaz-1110 tp) unsaturated resin with1.5% hardener was used for the matrix. table (2-1) shows the composition of glass fibers and table (2-2) shows some of the reported properties of e-glass fibers and polyester found in the literature seems to vary according to their manufacturing source. table 2-1 , composition of glass fibers: [7]. material silicon dioxide aluminu m oxide boric oxide sodium oxide and potassium oxide magnesium oxide titanium dioxide iron oxide iron calcium oxide e-glass (range %) 52 to 56 12 to 16 5 to 10 0 to 2 0 to 5 up to 1.5 0 to 0.8 0 to 1 16 to 25 table 2-2, mechanical properties of fiber glass and polyester (resin) [7]. material density g/cm3 modulus of elasticity (gpa) strength (mpa) poisson’s ratio e-glass 2.54 72.4 3450 0.2 polyester 1.1-1.4 2.1-3.4 34.5-103 0.37-0.4 2.2. manufacturing processes (hand layup) the choice of a manufacturing process depends on the type of matrix and fibers. hand lay-up is the simplest and oldest open molding method of the composite fabrication processes, laminate panels were prepared according to astm d5687 [8], and the following stages of preparation were used: 1. the mould, which was made of a thermal glass plate 60*80cm2, was cleaned and treated with a release wax in order to prevent the finished product from sticking to the frame. the liquid resin was mixed with 1.5% hardener and applied over the wax. 2. the first layer of reinforcing material (45*75cm2 woving roving mat) was laid over the resin while it was still wet; it was embedded into the resin and completely wetted with a stiff brush. 3. any air bubbles trapped under the reinforcement were removed by working them out to the edge using special rollers. 4. the application of additional layers (3 layers) of fibers and resin was repeated to produce the final laminate [csm]3, [0/90]3, [0/90, ±45, 0/90], [csm, 0/90, csm], [0/90, csm, 0/90] with a constant volume fraction of about 33%. 5. a heavy weight was applied on the cover of the mould giving a pressure of 4135 n/m2 to prevent buckling during curing. hussain j. al-alkawi al-khwarizmi engineering journal, vol. 8, no.3, pp1 -12 (2012) 3 6. the laminate was left in the mould to cure for 24 hours at room temperature. 7. the laminate was trimmed to remove excess resin. 8. the product laminate was left 3 hours in oven at 60oc in order to be sure that the curing process was achieved. 9. the part was ready to be cut into specimens; it was left 3 weeks before testing was carried out. 2.3. specimen preparation the specimens were cut out of 40*70 cm2 panels and followed by polishing the cut edges in two stages in order to remove flaws and to obtain smooth and crack-free surfaces. silicon carbide paper of grade 400 and 800 was used for this purpose. 2.4. the tensile test specimens 2.4.1. matrix in order to find the mechanical properties of the matrix, tensile specimens were prepared according to astm d 638-97 [9] as shown in figure 2-1. fig. 2-1. polyester tensile test specimen, (dimensions are in mm). [9]. 2.4.2. composite material tests specimens were designed according to astm d3039 standards [10] as shown in figure (2-2). fig. 2-2. composite tensile test specimen (dimensions in mm). 2.4.3. tensile tests procedure the tensile tests were performed in a tinius olsen (h50kt) test machine at room temperature. the maximum load capacity of the test machine is 5 ton. figure (2-3) shows the specimen clamped securely in the fixture before applying the load. a constant speed of 1 mm/min was used during the test until specimen failed [10]. fig. 2-3. close up of specimen fixture. specimen hussain j. al-alkawi al-khwarizmi engineering journal, vol. 8, no.3, pp1 -12 (2012) 4 the test results show that different fracture modes observed like brittle fracture of the matrix and breaking of the fibers gradually depending on the type of layers used in laminates. figure (2-4) shows some examples of tensile test specimens after failure. fig. 2-4. examples of tensile specimens after failures. 2.5. fatigue test specimens preparation the specimens were prepared according to astm d 3479/d 3479m–96, standard test method for fatigue of polymer matrix composite materials [11]. fatigue specimens were cut in suitable dimensions to satisfy the machine test section that suited for flat plate specimens. figure (2-5) shows the shape and dimensions of fatigue specimen [12]. fig. 2-5. fatigue specimens (all dimension in mm) [12]. 2.5.1. fatigue tests procedure the type of fatigue test is a cyclic bending loading procedure. the purpose of the test is to generate s-n data (stress vs. number of cycles) for each specimen of laminate at room temperature. the avery fatigue testing machine type-7305 was used to apply reverse loads as shown in figure (2-6). grips are provided for the bend test where the load is imposed at one end of the specimen by an oscillating spindle driven by means of a connecting rod, crank, and double eccentric attachment. the eccentric attachment is adjustable to give the necessary range of bending angle. the applied stress is calculated from the deflection. a revolution counter is fitted to the motor to record the number of cycles. the cycling rate is 1400 rpm [12]. fracture hussain j. al-alkawi al-khwarizmi engineering journal, vol. 8, no.3, pp1 -12 (2012) 5 fig. 2-6. a) avery fatigue testing machine type 7305, b) close up of specimen fixture. the machine was adjusted at stress ratio r= -1. a series of experiments were performed on each set of specimens by changing the deflection angle each time and recording the number of cycles to failure. examples of some specimens after fatigue test failure are shown in figure (2-7). fig. 2-7. fatigue failure of composite specimens. fatigue damage in the composite is initiated by the formation of transverse matrix cracks, due to the presence of higher stress concentration and induce localized ply delamination. as the fatigue cycling continues, matrix cracks and ply delamination grows and cause weft fiber bundles (at 90o to loading direction) to split and fracture setting the stage for final fracture. 3. experimental results and discussion 3.1. tensile test results table 3-1 shows the experimental tensile strength of the matrix at room temperature (rt). table 3-1, tensile test for matrix (polyester) at (rt). no. matrix , resin specimens ultimate tensile stress (uts)mpa average uts mpa 1 polyester,topaz 1110 1 2 3 33.38 31.75 32.59 32.567 table (3-2) shows the same results for fibre strengthened composite material at room temperature and under the same volume fraction of fibre(about 33%) with different laminates (3 layers of different fibre orientation). it can be observed that regardless of the orientation of the fibres, the addition of the fibres contributes to strengthening of the composite. however, the [0/90]3 and [0/90, csm, 0/90] orientations yield the highest strengthening in the range of 7.32 to 7.64 times the strength of the original matrix. strengthening of the other three fibre orientation, specimen fixture dial gauge fatigue failure hussain j. al-alkawi al-khwarizmi engineering journal, vol. 8, no.3, pp1 -12 (2012) 6 [csm] 3, [0/90, ±45, 0/90] and [csm, 0/90, csm], is only in the range of 4.04 to 4.64 times the strength of the original matrix. elastic modulus (e) was calculated by constructing a secant between two points, typically at strain values of 0.001 and 0.003 [10]. table 3-2, tensile tests for composite materials at (rt). no. laminate description specimens no. uts , ( mpa) utsave(mpa) 1 [csm]3 4 5 6 142 142.5 147.5 144 2 [0/90,±45,0/90] 7 8 9 155 121 119 131.667 3 [csm,0/90,csm] 10 11 12 155 123.3 173.5 150.6 4 [0/90]3 13 14 15 256.7 240 250 248.9 5 [0/90,csm,0/90] 16 17 18 221 249.5 245 238.5 3.2. fatigue test results tables (3-3) to (3-7) show fatigue test results at constant amplitude loads for laminates [csm]3 , [0/90]3 , [0/90,±45, 0/90] , [0/90, csm, 0/90] and [csm, 0/90, csm] respectively. the s-n curve was obtained from these results as shown in figure (3-1). the equation of power law regression is given by [13]: = … (3.1) where (  is the applied stress amplitude, and (a), (b) are the fitting parameters. the regression constants representative of the fatigue trends, from the model, and the fatigue strength limit at 107 cycles are given in table (3-8).the fatigue strength for the laminates to their tensile strength is 0.545, 0.379, 0.203, 0.15 and 0.418 for [csm]3 , [0/90]3 , [0/90, ±45, 0/90] , [0/90, csm, 0/90] and [csm, 0/90, csm] laminate respectively. the higher fatigue strength is 94mpa for laminate [0/90]3 and the lower fatigue strength is 26.7mpa for [0/90, ±45, 0/90] laminate. then it can be observed that the orientation of fiber glass-mat has strong effect on the fatigue strength of these laminates. these results are in agreement with finding of z. hashin [3] and wedad al-azzawy [4]. table 3-3, fatigue results for laminate [csm]3. specimens no. applied stress amplitude( ) number of cycles to failure (nf) (nf)ave. 19, 20, 21 128 60000, 50000,55000 55000 22, 23, 24 116 360000, 406000, 380000 382000 25, 26, 27 103 900000, 989000, 850000 913000 28, 29, 30 90 1150000, 1220000, 1380000 1250000 table 3-4, fatigue results for laminate [0/90]3. specimens no. applied stress amplitude( ) number of cycles to failure (nf) (nf)ave. 31, 32, 33 144.5 18000, 16000, 20000 18000 34, 35, 36 130 296000, 332000, 420000 349000 37, 38, 39 115.5 792000, 820000, 920000 844500 40, 41, 42 101 1080000, 1200000, 1350000 12١0000 hussain j. al-alkawi al-khwarizmi engineering journal, vol. 8, no.3, pp1 -12 (2012) 7 table 3-5, fatigue results for laminate [0/90, ±45, 0/90] specimens no. applied stress amplitude ( ) number of cycles to failure (nf) (nf)ave. 43, 44, 45 111 20000, 25000, 15000 20000 46, 47, 48 99.5 31500, 24500, 28000 28000 49, 50, 51 88.5 50500, 59000, 69000 59500 52, 53, 54 77.5 78000, 86000, 101500 88500 55, 56, 57 55.5 400000, 350000, 450000 400000 table 3-6, fatigue results for laminate [0/90, csm, 0/90. specimens no. applied stress amplitude ( ) number of cycles to failure (nf) (nf)ave. 58, 59, 60 156 5000, 5500,4500 5000 61, 62, 63 140.5 6500, 7000, 7500 7000 64, 65, 66 124.5 21000, 17500, 18500 19000 67, 68, 69 109 53000, 70000, 60000 61000 70, 71, 72 75 273000, 301000, 364000 312700 73, 74, 75 58 400000, 450000, 515000 455000 table 3-7, fatigue results for laminate [csm, 0/90, csm]. specimens no. applied stress amplitude ( ) number of cycles to failure (nf) (nf)ave. 76, 77, 78 102.5 90000, 110000, 160000 120000 79, 80, 81 92.5 580000, 610000, 671500 620500 82, 83, 84 82 1250000, 1430000, 1580000 1420000 85, 86, 87 72 1520000, 2360000,2150000 2010000 table 3-8, fatigue parameters and fatigue strength for laminates. laminate description a b fatigue strength at 107 cycles (mpa) [csm]3 388.848 -0.09921 78.579 [0/90]3 296.738 -0.071088 94.353 [0/90, ±45, 0/90] 1050.55 -0.2278 26.718 [0/90, csm, 0/90] 841.735 -0.1959 35.799 [csm, 0/90, csm] 398.75 -0.1138 63.694 hussain j. al-alkawi al-khwarizmi engineering journal, vol. 8, no.3, pp1 -12 (2012) 8 fig. 3-1.s-n curve for all laminates used in this study. 3.3. improvement factor 3.3.1. strength improvement factor (sif) several factors are responsible for the improvement in strength: volume fraction of fiber, type of fiber, orientation of fiber, type of matrix. therefor the laminates used in this study were manufactured from the same matrix and same fiber under the same volume fraction of fibers by using different type of fiber glass mat (chopped strand mat, woving roving mat). table (3-9) shows strength improvement factor (sif) for laminates [csm]3, [090]3, [ 0/90, csm, 090], [csm, 0/90, csm], [0/90, ±45, 0/90] based on the laminate [0/90,±45, 0/90] which have the lowest tensile strength. it can be observed that the highest strength improvement factor was 89% for laminate [0/90]3. sif= ×100 …(3-2) where uts is the ultimate tensile stress and utsref is the ultimate tensile stress of [90/0, ±45, 0/90] laminate (the lowest ultimate tensile strength). table 3-9, the percentage strength improvement factor (sif %) for laminates laminate description sif % [csm]3 9.366 [0/90]3 89.037 [0/90, csm, 0/90] 81.13 [csm, 0/90, csm] 14.379 [0/90,±45, 0/90] 0 3.3.2. fatigue life improvement factor (flif) table (3-10) shows empirical life (number of cycles to failure) for each laminate at different applied stresses amplitude. the lowest life was for [0/90, ±45, 0/90] laminate and slightly higher for [0/90, csm, 0/90] laminate. table (3-11) shows the percentage of fatigue life improvement factor (flif %) at each applied stresses flif= . . × 100 …(3-3) where the nf is the number of cycles to failure and nfref is the number of cycles of laminate [0/90, ±45, 0/90] (the lowest life at each level of applied stress as a reference).it can be observed the (flif) increased with decreasing of applied stresses, and it can perform the relationship between the applied stress amplitude and the (flif) as the equation of power law regression is given by[14]: = ( %) …(3-4) where (  is the applied stress amplitude, and (c), (d) are the fitting parameters which are dependent upon the type of the fiber glass mat. the regression constants representative of the (flif) trends, from the model, are given in table (312).figure (3-2) show these relations. 1000.00 10000.00 100000.00 1000000.00 10000000.00 log (number of cycles to failure nf) 40.00 80.00 120.00 160.00 ap pl ie d st re ss m pa [0/90]3 [csm, 0/90, csm] [0/90, csm, 0/90] [0/90, 45, 0/90] [csm]3 hussain j. al-alkawi al-khwarizmi engineering journal, vol. 8, no.3, pp1 -12 (2012) 9 table 3-10, empirical number of cycles to failure (nf) for laminates at different level of applied stresses amplitude. description of laminates applied stresses amplitude 140mpa 120mpa 100mpa 80mpa [csm]3 29280 140349 895826 8659287 [0/90]3 36067 303992 3783184 82783097 [0/90,±45,0/90] 7045 13658 32257 80645 [0/90, csm,0/90] 9350 21740 59149 200705 [csm, 0/90,csm] 9873 38262 189917 1349419 table 3-11, the percentage of fatigue life improvement factor (flif %) a different applied stresses amplitude. description of laminates 140mpa 120mpa 100mpa 80mpa [csm]3 16 24.46 32 41.39 [0/90]3 18.43 32.58 45.89 61.37 [0/90, csm,0/90] 3.01 4.88 5.84 8.07 [csm, 0/90,csm] 3.8 10.81 17.07 24.93 [0/90, ±45, 0/90] 0 0 0 0 table 3-12, fatigue life improvement parameters. laminate description c d [csm]3 728.507 0.58119 [0/90]3 545.942 0.4528 [0/90, csm, 0/90] 273.02 0.5691 [csm, 0/90, csm] 213.546 -0.2803 hussain j. al-alkawi al-khwarizmi engineering journal, vol. 8, no.3, pp1 -12 (2012) 10 fig. 3-2. fatigue life improvement factor % at different applied stresses. 4. conclusions at similar volume of fraction the laminates showed: 1. difference in strength with the difference construction of laminate (type of laminates). the maximum tensile strength for [0/90]3 and [0/90, csm, 0/90] laminates are higher than strength for [csm]3 ,[0/90, ±45, 0/90] and [csm, 0/90, csm] laminates (see table 3-2). 2. the fatigue test results for laminates at similar volume of fraction, showed different in fatigue strength with the different construction of laminate (type of laminates). the higher fatigue strength for these laminates was found (94mpa) at 107cycles for [0/90]3 laminate (see table 3-8). 3. the higher percentage of the strength improvement factor (sif %) was 89% for [0/90]3 laminate (see table 39). 4. the fatigue life improvement factor (flif) for all laminates was increased with the decreased of applied stresses, the highest (flif %) was 18.43%, 32.58%, 45.89%and 61.37% for [0/90]3 laminate at 140mpa, 120mpa, 100mpa and 80mpa respectively as compared with other laminates used (see table 3-11 and figure 3-2) 5. the higher percentage of fatigue strength of laminates to their strength was (0.545) for [csm]3 laminate and the lower percentage of fatigue strength to their strength was (0.15) for laminate [0/90, csm, 0/90]. 6. the maximum strength laminate was the best fatigue behavior at constant amplitude stress which was for laminate [0/90]3 (see figure 31) 5. references [1] william, d. callister, jr. “materials science and engineering: an introduction”, 7th edition, john wiley and sons, inc.2007. 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[8] asm handbook, “space simulation; aerospace and aircraft; composite materials”, solid, vol. 15, 2000. http://mihd.net/yn9up8 [9] astm d638. standard test method for tensile properties of plastics, annual book of astm standards american society for testing and material. philadelphia, pp. 4654.1997 [10] j.m.hodgkinson “mechanical testing of advanced fiber composites “2006. [11] astm d3039. 1995. standard test method for tensile properties of polymer matrix composite materials. annual book of astm standards, american society for testing and materials, philadelphia. 14(2): 99-109. [12] avery 7305, “users’ instructions manual”.1976 0.00 20.00 40.00 60.00 80.00 flif % 80.00 100.00 120.00 140.00 a pp lie d st re ss m pa [0/90]3 [csm]3 [csm, 0/90, csm] [0/90, csm, 0/90] http://mihd.net/yn9up8 hussain j. al-alkawi al-khwarizmi engineering journal, vol. 8, no.3, pp1 -12 (2012) 11 [13] daniel d. samborsky, pancasatya agastra and john f. mandell, “fatigue trends for wind blade infusion resins and fabrics “2010 aiaa sdm, wind energy session, orlando, aiaa-2010-2820. [14] sharp p.k., barter s.a. and clark g. “localized life extension specification for the f/a-18.y470x19 pocket. melbourne: dsto-tn-0279. (2000). )2012( 1 12، صفحة 3، العدد 8مجلة الخوارزمي الھندسیة المجلد حسین جاسم العلكاوي 12 تأثیر نوع حصیرة اال لیاف الزجاجیة على سلوك الكالل للمواد المتراكبة عند نسبة حجمیھ ثابتة لاللیاف الزجاجیة ***عبد الجبار حسین **ظافر صادق الفتال *حسین جاسم العلكاوي الجامعة التكنولوجیة/ قسم ھندسة الكھرومیكانیك* الجامعة التكنلوجیة/ قسم ھندسة المكائن والمعدات** رئاسة جامعة بغداد/ قسم شؤون الطلبة*** ةالخالص ھ من البولستر وبنسبھ حجمیھ ثابتة ھدف البحث الحالي الى دراسة تأثیر نوع طبقات الاللیاف الزجاجیة على سلوك الكالل للمواد المتراكبھ المصنعی تمتلك أدنى حد للكالل عند 0/90,±45, 0/90] ,[csm, 0/90 ,0/90] [أظھرت نتائج البحث ان المواد المصنعھ من .%٣٣لأللیاف الزجاجیة مقدارھا على الرغم من انھا تمتلك اجھاد شد اقصى مختلف وان أفضل الطبقات 3[csm] [csm, 0/90, csm],و 3[0/90]من تلك للمواد المصنعھ من ١٠٧ .3[0/90]ھي بحث علي الموسوي 97 al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 7, no. 4, pp 97-102 (2011) استعمال تقنیة الطالء بمعیقات الّلھب لحمایة المنشآت المدنیة والصناعیة من الحرائق نصر عبد األمیر علوش علي جاھل سلمان عباس علي محمودعلي إبراھیم الموسوي بابل –المعھد التقني aliibrahim76@yahoo.com :البرید االلكتروني (received 23 march 2011; accepted 11 september 2011) الخالصة نشآت المدنیة والصناعیة المصنعة من المواد المتراكبة البولمیریة المتقدمة المقواة باأللیاف بطالئھا بطبقة تم في ھذا البحث زیادة إعاقة الّلھب ألجزاء الم إلعاقة الّلھب ومنع إنتشاره لطالء سطح راتنج البولي أستر (3mm)إستعمل رابع ُأوكسید األنتیمون كطبقة طالء بسمك . سطحیة مكونة من مادة معیقة لّلھب (siropol 8340-pi) ٤٩(المقوى بألیاف ھجینة مكونة من حصیرة ألیاف الكاربون وألیاف كیفالر) (º ٠ -º وتعریضھا إلى لھب مباشر متولد )٤٥ ، ودراسة مدى مقاومة ھذه الطبقة للحرارة ومدى قدرتھا على حمایة (20mm,15,10)وبمسافات تعرض مضتلفة (2000ºc)من ُشعلة غازیة درجة حرارتھا لقد أظھرت النتائج العملیة التي تم التوصل إلیھا من إختبار التعریة الحراریة تحسن مقاومة المادة المتراكبة للحرارة العالیة بعد .راكبة التي تحتھا المادة المت .إضافة طبقة رابع ُأوكسید األنتیمون وتزداد ھذه المقاومة مع زیادة مسافة التعرض لحرارة الّلھب .عاقة الّلَھب ، مادة متراكبة ، ألیاف ھجینة إ :المفتاحیة الكلمات المقدمة . ١ یمكن تعریف معیقات الّلَھْب على إنھا مواد كیمیائیة لھا القدرة على تحمل الّلھب المباشر حیث تعمل على منع نفاذه داخل المادة تضاف معیقات . وكذلك منع إنتشاره وحتى إخماده بشكل كامل مواد لیس لھا القدرة على مقاومة الّلھب لخفض قابلیة الّلَھْب إلى إشتعالھا مثل اللدائن، األنسجة ، والدوائر اإللكترونیة ومواد أخرى تحتوي معظم معیقات الّلھب على عناصر الفسفور واألنتیمون و . الكلور و البروم و البورون والنتروجین ،ومن األمثلة علیھا ھي التي تحتوي على عناصر الكلور و أكاسید األنتیمون والمواد البروم التي تدعى بالمركبات الھالوجینیة ومركبات كل من ].1[الفسفور والبورون والنتروجین ھنالك إسلوبان معروفان إلعاقة الّلھب ، یعتمد األسلوب األول على منع وصول األوكسجین إلى منطقة اللھب عن طریق تولید راق حیث تسبب ھذه الغازات في تسمم غازات غیر قابلة لإلحت أما اإلسلوب الثاني فإنھ یعتمد . االّلھب بالجذور الحرة وإخماده على نظریة اإللتھاب الحراریة والتي تنص على إن معیقات الّلھب تحتاج إلى طاقة حراریة كي تتفكك مما یؤدي إلى خفض حرارة التالي سطح المادة إلى درجة حرارة أقل من درجة إتقادھا وب ].2[یتوقف اإلحتراق بزیادة إعاقة الّلھب [abbas, ali,mushtaq]قام الباحثون للمواد المتراكبة عن طریق إضافة مادة بورات الزنك بشكل طبقة على سطح مادة متراكبة مكونة من راتنج (4mm)طالء بسمك اإلرلدایت المقوى بألیاف ھجینة من ألیاف الكاربون وألیاف ر وُعرض ھذا النظام إلى ّلھب مباشر متولد من ُشعلة ُأوكسي كیفال أستیلینیة و ُشعلة غازیة وبمسافات تعرض مختلفة (20mm,15,10) حیث تم الحصول على أفضل النتائج عندما تكون مسافة التعرض كبیرة و أكبر نسبة للطبقة الحامیة والتي ھي قام [ali]لباحثا]. 3[ولكال الشعلتین ) 30%نسبة (بورات الزنك (ay103)بطالء سطح مادة متراكبة مكونة من راتنج اإلرلدایت كیفالر الھجینة بطبقة من مادة معیقة المقوى بألیاف الكاربون وتعریض ھذه الطبقة (4mm)لّلھب متمثلة ببورات الزنك وبسمك من الطالء إلى لھب مباشر متولد من الُشعلة اُألوكسي أستلینیة ودراسة مدى (20mm,15,10)رض مختلفة وبمسافات تع أظھرت .مقاومة ھذه الطبقة للحرارة ومدى حمایتھا للطبقة التحتیة نتائج اإلختبارات العملیة زیادة كبیرة في المقاومة الحراریة وإعاقة الّلھب للمادة المتراكبة بعد طالئھا ببورات الزنك إضافة تعرض للُشعلة إلى إرتفاع مقاومة الّلھب مع زیادة مسافة ال [mostashari, nia , moafi]قام الباحثون ]. 4[الحراریة (ia بإستعمال مجموعتین من المواد المعیقة للھب الھایدروكسیدیة (, iia ودراسة تأثیرھا على قابلیة إشتعال ألیاف القطن الصناعیة ]٥.[ بتقدیم دراسة متقدمة عن horacek,pieh] [قام الباحثان لمواد المعیقة لّلھب النایتروجینیة في الطالء لحمایة إستخدام ا sodium)المواد اللدائنیة من مھاجمة الّلھب حیث إستخدما مواد silicate) و(vermcular) كمادة معیقة لّلھب مضافة إلى الطالء لتحسین كفاءتھ لمقاومة الّلھب ، حیث أوضحا في النتائج -تقوم ببناء رغوة عضویةالتي حصال علیھا بأن ھذه المعیقات بوجود (intumescent action)العضویة أثناء فعل اإلنتفاخ النار وھذه الرغوة تتغیر ببطأ إلى رغوة العضویة نقیة ُتحیط ,edward]قدم الباحثان . [6]الطبقات السفلى للمادة michael] بحثًا یتضمن دراسة تأثیر حالة المادة المعیقة للھب mailto:aliibrahim76@yahoo.com )2011( 102-97، صفحة 4، العدد 7مجلة الخوارزمي الھندسیة المجلد الموسوي إبراھیمعلي 98 تنج البولي بروبلین لّلھب وثباتیتھ لألشعة فوق على مقاومة را البنفسجیة حیث إستخدما ثالث وخامس ُأوكسید األنتیمون على شكل حبیبات ذات تركیب غروي إذ أوضحت النتائج التي حصال ) burn ex 2000(علیھا بأن النظام المعیق لّلھب المعروف بإسم ة لّلھب حصل على خواص فیزیائیة جیدة وخواص جمالیة وإعاق . [7]عند مستویات تحمیل واطئة جدًا (antimony tetroxide)رابع ُأوكسید األنتیمون .١.١ إلى معیقات الّلھب ) sb2o4(ینتمي رابع ُأوكسید األنتیمون ثالث ُأوكسید وكسید مزدوج متكون من ُأھو غیر العضویة ، و تج من تسخین ثالث أو خامس ُأوكسید األنتیمون ، ینو األنتیمون خامس ُأوكسید األنتیمون أو معدن األنتیمون إلى درجة یتم إضافة ھذا اُألوكسید على شكل ) . (900ºc-800ºcحرارة حشوات إلى المواد اللدائنیة بسبب التوصیل الحراري الضعیف جدا لھًا والغرض من ھذه اإلضافة ھو إلحداث تغییرات في یتم إضافتھ بشكل طبقة خارجیة معامالت توصیلھا الحراري أو رابع ُأوكسید األنتیمونیفقد . لحمایتھا من الّلھب المباشر متحوًال إلى 1060ºc)(األوكسجین عند تسخینھ بشدة إلى حوالي یوضح ) ١(الشكل رقم . ]8[ )sb2o3( ثالث ُأوكسید األنتیمون .التركیب البلوري لرابع ُأوكسید األنتیمون وكسید األنتیمون في الھواء یتكون رابع ُأوكسید عند تسخین ثالث ُأ :األنتیمون كما في المعادلة التالیة sb2o3 + 0.5 o2 → sb2o4 δh = −187 kj/mol ) (800ºcوعند تسخین خامس ُأوكسید األنتیمون إلى درجة حرارة فإنھ یفقد اُألوكسجین ویتحول إلى رابع ُأوكسید األنتیمون وحسب :المعادلة التالیة sb2o5 → sb2o4 + 0.5 o2 δh = −64 kj/mol ]8[التركیب البلوري لرابع ُأوكسید األنتیمون -١-لشكل رقم ا (composite material)المادة المتراكبة . ٢.١ من جمع (composite material) تتكون المادة المتراكبة الفیزیائیة والغرض من ھذا مادتین مختلفتي الخواص المیكانیكیة و الجمع ھو إستنباط خواص جدیدة لم تكن متوفرة في المواد یوجد في الطبیعة الكثیر من األمثلة على المواد المتراكبة . األصلیة أما في الصناعة فإن ]. 9[ومنھا ألیاف السلیلوز مع مادة الخشب لتصنیع تقویة الراتنجات باأللیاف الصناعیة ھي األكثر إنتشارًا، و :مادة متراكبة یجب توفر مادتین ھما (matrix material)المادة األساس -١ تكون مواد األساس أما مواد معدنیة متكونة من المعادن وسبائكھا ، أو قد تكون مواد سیرامیكیة ، كذلك تكون المادة األساس مواد ن خواص بولیمیریة وھي األكثر إستعماًال وإنتشارًا ِلما تتمیز بھ م ].10[میكانیكیة وفیزیائیة جیدة . (reinforcing material) مادة التقویة -٢ والتي تكون بقطر ھناك عدة طرق للتقویة منھا التقویة بالدقائق وبأشكال مختلفة منھا اإلبریة والكرویة والِقشریة 1µm)(أكبر من ویكون قطر الدقائق أقل من ، كذلك تتم التقویة بالتشتت (0.1µm) . أما أكثر أسالیب التقویة شیوعًا فھي التقویة باأللیاف نظرًا ِلما تتمیز بھ من متانة جیدة ومقاومة نوعیة عالیة مقارنة بالمواد الراتنجیة ، وتكون األلیاف بأنواع وأشكال مختلفـة فمنھا ما ].١١[یكون بشكل مستمر أو مَقطْع أو بشكل ظفائر محاكة (polyester resin) لبولي أستر راتنج ا. ٣.١ تنتمي راتنجات البولي أستر غیر المشبع ومن ضمنھا إلى مجموعة الراتنجات المتصلدة بالحرارة حیث تتمیز ھذه الراتنجات بعدم إمكانیة إعادة تشكیلھا بالحرارة بعد تحولھا إلى مادة صلبة عضھا وھو ما نتیجة لتكون سالسل بولیمیریة طویلة متشابكة مع ب یتصف راتنج .) cross linking(یسمى بالربط التشابكي البولي أستر بخواص حراریة جیدة إذ یتحمل الحرارة لغایة )260ºc (بمقاومة كھربائیة ممتازة ومقاومة وكذلك یمتاز كیمیائیة للمذیبات واألحماض واألمالح ومقاوم للتآكل والتأثیرات ].11[لھشاشة البیئیة ولكنھ یتصف بالضعف وا تستعمل راتنجات البولي أستر بشكل عام في المجاالت التي ترتفع فیھا درجة الحرارة إلى مدى كبیر نسبیًا ،كذلك یستعمل . البولي أستر في التطبیقات التي تتطلب جودة عالیة في السطح یضاف البولي أستر إلى األلیاف الزجاجیة لصناعة ھیاكل القوالب مكونات أجسام الطائرات والسیارات وغیرھا من الصناعات و ]9.[ (reinforcing fibers)ألیاف التقویة . ٤.١ الخمولیة حیث :تمتلك ألیاف الكاربون العدید من المزایا منھا تمتلك مقاومة عالیة ضد الرطوبة وألغلب المواد الكیمیائیة الشائعة ة عالیة على طول محور األلیاف ، ، موصلیة كھربائیة وحراری تتضمن . وثبات األبعاد وإنخفاض التمدد الحراري المحوري (turbostraticألیاف الكاربون بلورات صغیرة من مادة (graphite أما . ]12[والتي ھي أحد األشكال المتآصلة للكاربون وھي التسمیة التجاریة أللیاف األرماید ) ٤٩(ألیاف كیفالر یث تمتلك مقاومة شد ومعامل مرونة عالیین مع كثافة العضویة ح تساوي تقریبًا نصف كثافة األلمنیوم إضافة إلى إمتالكھا متانة إن إعاقة الّلھب العالیة التي . جیدة ومعامل تمدد حراري سالب تتصف بھا ھذه األلیاف جعلھا كثیرة اإلستعمال في المجاالت یوضح ) ٢(شكل رقم ال. ]١٣[العسكریة وتطبیقات الطیران .التركیب الكیمیائي أللیاف كیفالر )2011( 102-97، صفحة 4، العدد 7مجلة الخوارزمي الھندسیة المجلد الموسوي إبراھیمعلي 99 تھدف ھذه الدراسة إلى تحقیق ھدف أساسي ھو تحضیر وتصنیع مادة معیقة لّلھب مكونة من رابع ُأوكسید األنتیمون لھا القدرة على إعاقة إنتشار الّلھب وبالتالي إخماده مما یقلل من األخطار المتولدة . من الحرائق الجزء العملي . ٢ یتضمن الجزء العملي أنواع المواد األولیة وكیفیة تحضیرھا الذي تم إجراءه على المادة التعریة الحراریة إضافة إلى إختبار .المتراكبة المواد المستخدمة في البحث .١.٢ :تم في ھذا البحث إستعمال المواد التالیة a رابع ُأوكسید األنتیمون (antimony tetroxide) . (10µ) وبحجم ُحَبیبي (sb2o4)إستعمل رابع ُأوكسید األنتیمون وقد تم إجراء الفحص الكیمیائي علیھ بواسطة )%٩٩.٥(وبنقاوة )(x-ray fluorescent . الشركة المجھزة لھذا اُألوكسید ھي (bdh chemical ltd pool england) . b راتنج البولي أستر(siropol 8340-pi) . saudi international)ھذا الراتنج مجھز من قبل شركة resin .ltd (sir)) . c ألیاف الكاربون وكیفالر الھجینة. الھجینة ) ٤٩(تم إستعمال حصیرة من ألیاف الكاربون وكیفالر )º ٠ º ذات كثافة )٤٥(1.75 g/cm3) و(1.45 g/cm3) على .(k and c moulding ltd)من ِقبل شركة التوالي والمجھزة نماذج إختبار التعریة الحراریة . ٢.٢ تتكون نماذج إختبار التعریة الحراریة من طبقتین ، األولى ، تلیھا 3mm)(متكونة من رابع ُأوكسید األنتیمون وتكون بُسمْك طبقة المادة المتراكبة المكونة من راتنج البولي أستر غیر المشبع ، لذلك 5mm)(وتكون بُسمْكألیاف الكاربون وكیفالر الھجینة و ) ٣(والشكل رقم 8mm)± ١(%یكون مجموع سمك النموذج . یمثل رسمًا تخطیطیًا لشكل النموذج تتم طریقة تصنیع نماذج إختبار التعریة الحراریة بتھیئة قطع تم ) . mm 100( دائریة الشكل من األلیاف الھجینة وبقطر إستعمال القولبة الیدویة في تحضیر ھذه النماذج ،حیث ُیطلى بمادة الورنیش لتفادي إلتصاق ) ٤(القالب الموضح في الشكل رقم polyvinyl(النماذج بعدھا یرش القالب بمادة بولي فنیل الكحول alcohol ( یتم إضافة . الذي یسھل فصل النماذج من القالب إلى راتنج البولي أستر غیر ) cobalt octoatel(المادة المعجلة وتخلط معھ ) %6(المشبع والتي تحتوي على كوبالت فعال بنسبة ُیصلد ھذا الراتج بإضافة مادة بیروكسید مثیل أثیل كیتون . جیدًا (mekp) توضع كمیة من الراتنج على سطح %).٢(إلیھ بنسبة ام بعدھا توضع القالب الداخلي وتنشر بفرشاة لضمان توزیعھ بانتظ الطبقة األولى من األلیاف ثم نضع كمیة اخرى من الراتنج علیھا تم . وھكذا لبقیة الطبقات لتتكون مادة متراكبة بالسمك المطلوب إستخدام الطریقة الوزنیة في حساب كمیة كل من األلیاف والراتنج ) ٤٠(%المستخدمة في تصنیع المادة المتراكبة ،حیث إسُتخدم نسبة ) ٦٠(%یة من راتنج البولي أستر غیر المشبع ونسبة وزن . وزنیة من األلیاف بعد ذلك توضع المادة المعیقة لّلھب وھي رابع ُأوكسید األنتیمون على المادة المتراكبة ویتم كبسھا في القالب وتترك + ألیاف + راتنج (بعدھا یتم إستخراج المادة المتراكبة . لتتصلب بعدھا ). ساعة ٢٤(وتترك لتتصلب لمدة ) قة للھبالمادة المعی إلكمال ) 75ºc(توضع المادة المتراكبة في فرن درجة حرارتھ .التصلب ].9[التركیب الكیمیائي أللیاف كیفالر -٢-الشكل رقم 5mm 3mm وكسید األنتیمونُأطبقة رابع .إختبار التعریة الحراریة نموذج -٣-الشكل رقم طبقة المادة المتراكبة .التعریة الحراریة اختبارقالب تصنیع نماذج ٤-الشكل رقم 2m m 10mm 100 mm )2011( 102-97، صفحة 4، العدد 7مجلة الخوارزمي الھندسیة المجلد الموسوي إبراھیمعلي 100 اختبار التعریة الحراریة . ٣.٢ إسُتعمل في ھذا اإلختبار الشعلة الغازیة وتبلغ درجة ي حیث تم إختبار المادة المعیقة لّلھب وھ) 2000ºc(حرارتھا رابع ُاوكسید األنتیمون بطریقة حساب درجة حرارة السطح وكما وتسلیطھا بمسافات ) ٥(موضح في الشكل رقم (20mm,15,10) . ومن أجل قیاس وخزن درجات الحرارة خلف النموذج والوقت والتي یطلق (ad)فقد تم إستعمال بطاقة التحویل ) بالثواني( ) ٦(اریة والموضحة في الشكل رقم علیھا منظومة المراقبة الحر تم تصمیم ھذه البطاقة من . والتي تثبت في الحاسوب اإللكتروني جامعة تكریت والتي تؤمن اإلظھار /قبل قسم الھندسة المیكانیكیة المباشر لتغیر كل قراءة مع الزمن على واجھة شاشة الحاسوب kوالتي یتم الحصول علیھا من خالل مزدوج حراري نوع . ول في الجھة المقابلة للُشعلة الحراریة موص النتائج والمناقشة. ٤ یمثل إختبار التعریة الحراریة بالشعلة الغازیة ) ٧(الشكل رقم رابع ُأوكسید األنتیمون على المادة العازلة والمعیقة لّلھب وھي حیث تبدأ درجة حرارة ) 10mm(وبمسافة تسلیط للشعلة قدرھا سطح الواقع خلف الشعلة الحراریة باإلرتفاع مع زیادة الفترة ال أن ھذه الزیادة في درجة حرارة السطح . الزمنیة لتسلیط الشعلة تقود إلى تقدم الّلھب داخل المادة المعیقة لّلھب وإختراقھ لھا مسببًا إندفاع الحرارة إلى الداخل مما ینتج عنھ إنھیار المادة المعیقة لّلھب ].14[رور الزمن مع م یبین إختیار التعریة الحراریة وبمسافة تسلیط ) ٨(الشكل رقم حیث نالحظ إنھ بزیادة ). 15mm(للشعلة الحراریة مقدارھا مسافة تسلیط الشعلة تزداد الفترة الزمنیة إلنھیار المادة المعیقة حالة لّلھب مع زیادة درجة حرارة السطح وبشكل أقل مما في ال ].15[السابقة یمثل إختبار التعریة الحراریة وبمسافة إختبار ) ٩(الشكل رقم )20 mm ( رابع ُأوكسید حیث نالحظ زیادة الفترة الزمنیة لمقاومة بزیادة المسافة الفاصلة بینھ وبین الشعلة الغازیة ، حیث األنتیمون أي إرتفعت سید األنتیمون رابع ُأوكأرتفع الوقت المقاوم إلنھیار مقاومتھ لّلھب وھذا یرجع إلى إنخفاض كمیة الحرارة التي تصل ماسك لتثبیت نموذج اإلختبار الشعلة بعد عن الشعلةالمنزلق تحكم ب الشعلة الحراریة kمزدوج حراري نوع .إختبار التعریة الحراریة -٥قمالشكل ر . منظومة المراقبة الحراریة -٦-الشكل رقم time,(sec) su rf ac e te m pe ra tu re ,(º c) .)(15mmمسافة اإلختبار -٨الشكل رقم 0 10 20 30 40 50 60 70 80 90 0 20 40 60 80 100 120 140 160 180 time,(sec) su rf ac e te m pe ra tu re ,(º c) .)10mm( االختبارمسافة -٧-الشكل رقم 0 10 20 30 40 50 60 0 20 40 60 80 100 120 140 160 180 )2011( 102-97، صفحة 4، العدد 7مجلة الخوارزمي الھندسیة المجلد الموسوي إبراھیمعلي 101 إلى المادة المعیقة لّلھب وبالتالي زیادة مقاومتھا إلختراق الّلھب ]4 .[ االستنتاجات. ٥ سمح برفع تقنیة الطالء السطحي بدًال من الحشوات عمالإست ١ .كبة وبشكل كبیر بدون أن تتلف ارتالم ةماددرجات حرارة ال وقابلیتھا على رابع ُأوكسید األنتیمونثبوت كفاءة طبقة طالء -٢ ھا لاعمحمایة طبقة المادة المركبة التي تحتھا مما یسمح بإست .في مواد الطالء تحسن المقاومة إلنتشار الّلھب بزیادة مسافة تسلیط الشعلة -٣ .(20mm)وأفضل مسافة ھي المصادر . ٦ [1] heinrich horacek , stefan pieh “ the importance of intumescent systems for fire protection of plastic materials ”, polymer international ,49 , 2000 . [2] flame retardants association(efra) european chemical industry council “ how do flame retardants” , 2006. [3] abbas a. al-jeebory ,ali i. al-mosawi, mushtaq t.ali. albdiry “experimental study of the effect of zinc borate on flame retardancy of carbonkevlar hybrid fibers reinforced composite materials” , alqadessiyah journal for engineering science, pp 126-132 . vol. 1,no.1 , 2008 . [4] ali i.al-mosawi “hybrid fire retardants to increasing combusting resistance for fibersreinforced composites” , national journal of chemistry, vol 41, 2011.pp 48-54 . [5] mostashari s. m ,nia y. k, moafi h. f “comparison between the selected hydroxides of groups ia and iia as flame retardants for cotton fabrics ” , journal of combustion, explosion, and shock waves , volume 43, number 2 / march, 2007 .pp 194-197 . [6] heinrich horacek and stefan pieh “ the importance of intumescent systems for fire protection of plastic materials ”, polymer international ,49,2000. [7] e edward a.myszak, jr. and michael t.sobus “ flame retardant developments for polypropylene ” nyacol nano technologies, inc. 2000. [8] a.r.horrocks ,d.price “flame retardant materials ” , woodhead publishing , 2003. [9] mallick ,p.k “fiber-reinforced composites: materials, manufacturing, and design” , 3rd edition , crc press , 2007. [10] william d. callister ,jr “materials science and engineering an introduction” , 6th edition , john wiley &sons , 2003. [11] michel biron “ thermoplastics and thermoplastic composites ” , first edition , elsevier , 2007. [12] liyong tong ,adrian p.mouritz ,michael k.bannister “3d fiber reinforced polymer composites” , first edition , elsevier science ltd , 2002. [13] degarmo ,e.p, j.t. black, and r.a. kohser “ materials and processes in manufacturing ” , 10th edition , john wiley & sons , 2008. [14] 1 huy k. tran , christine e. johnson , daniel j. rasky , and frank c.l hui “ phenolic impregnated carbon ablators (pica) as thermal protection systems for discovery missions ”, nasa technical memorandum , april , 1997 . [15] abbas a. al-jeebory , ali i. al-mosawi, kareem d. jaseem “improving thermal resistance for composite material reinforced by fibers by using flame retardant material layer ” , al-qadessiyah journal for engineering science, pp 42-50 . vol. 2,no.2 , 2009 . time,(sec) su rf ac e te m pe ra tu re ,(º c) ٠)(20mm االختبارمسافة -٩-الشكل رقم 0 10 20 30 40 50 60 70 80 90 100 110 120 0 20 40 60 80 100 120 140 160 180 ali i. al-mosawi al-khwarizmi engineering journal, vol. 7, no. 4, pp 97 -102 (2011) 102 using of coating technique by inorganic flame retardants to protect civil and industrial foundations from fires ali i. al-mosawi abbas a. mahmood ali j. salaman naser a.alwash technical institute-babylon email: aliibrahim76@yahoo.com abstract in the present research the flame retardancy to buildings and industrial foundations which are manufacturing from advanced polymeric composite material was increased by coating it with surface layer included flame retardant material. a(3mm) thick antimony tetroxide was used as a coated layer to retard and prevent the flame spread to the coating surface of polyester resin (siropol 8340-pi) reinforced with hybrid fibers as a woven roving )°٠°-٤٥( consist of carbon and kevlar (49) fibers, and exposed it to direct flame generated from gas torch at temperature of (2000ºc), at different exposed distance (10,15,20mm)and study the rang of resistance for this layer and its ability to protect the under composite material . the result obtained from erosion test show an improvement to the resistance of the composite material to high temperature after addition of antimony tetroxide layer and this resistance increased with increasing the exposed distance of flame . mailto:aliibrahim76@yahoo.com دراسة نظرية لامكانية زيادة القدرة الكهربائية المنتجة من المحطات التجارية في العراق 2226 / 2/ العدد 2 مجلة الخوارزمي الهندسية ,المجلد / حاتم فالح فاخر 1 دراسة نظرية المكانية زيادة القدرة الكهربائية المنتجة ارية في العراقبخمن المحطات ال د.مؤيد رزوقي حسن حاتم فالح فاخر قسم هندسة المكائن والمعدات قسم هندسة المكائن والمعدات الجامعة التكنولوجية الجامعة التكنولوجية (received 14 november 2005; accepted 4 april 2006) -ملخص البحث: يتضممن البحممث دراسمة نظريممة المكانيمة زيممادة انتمال القممدرة الكهربائيمة المنتجممة فمي العممراق و لم ممن طريمق لممق فمي المحطمات البخاريمة العاملمة فمي العمراق . لغمرس الدراسمة يلمرجل البخار لعالي لمياه تغ ية امسخنات الضغط ا النافممرية . و جنمموب بغممداد تنمماول البحممث مممالث محطممات بخاريممة من فمملة املممة فممي العممراق و ممي محطممة الممدورة , %6وبحمدود %11-11اوضحت النتائج امكانيمة زيمادة القمدرة الكهربائيمة ممن محطتمي المدورة والنافمرية بحمدود لمحطة جنوب بغداد . استنادا الى ظروف مل المحطات البخارية الحالية في العراق فمان اسمتخدام م ا االسملوب لممدة مالممة المى اربعمة سما ات يوميما مالوة لمى mw011سيؤدي الى امكانية زيادة القدرة الكهربائيمة بحمدود االضافية . بمولدات الديزل النتال ه القدرة تقليل فرفيات الوقود مقارنة المقدمة -1 يتطلمممممب توليمممممد الطاقمممممة الكهربائيمممممة موممممممما السمممممميطرة لممممممى القممممممدرة المتولممممممدة والمتوافقة مع طلب المستهل حيمث ان مدم التوافق )ممال ممن جمراع طمل احمدد وحمدات التوليد( سوف يؤدي الى بوط سمر ة دوران التوربينات وبالتالي انخ اس في قيمة التردد مما الكم فيمن ان تعمويس م ا الكهربائي . م النقفممممان الحافممممل فممممي القممممدرة الكهربائيممممة يتطلب زيادة انتمال الوحمدات العاملمة االخمرد زيممادة كتلممة البخممار المتولممد فممي و مم ا يتطلممب المرجمممل البخممماري والممم ي بمممدوره يعتممممد لمممى مدد استجابة المرجمل البخماري لهم ه الزيمادة مممممع مبممممات موافمممم ات البخممممار الممممداخل الممممى وربين البخاري ويتطلب تحقيق لم مليما الت al-khwarizmi engineering journal al-khwarizmi engineering journal, vol.2,no.2,pp 20-32 (2006) 02 2226 / 2/ العدد 2 مجلة الخوارزمي الهندسية ,المجلد / حاتم فالح فاخر 01 بعمممممس الوقمممممت وخفوفممممما فمممممي الوحمممممدات المن مممردة و ليمممن كمممان البمممد ممممن ايجممماد بمممديل مناسممب للتعممويس السممريع لهمم ا الممنقص فممي القممدرة الكهربائيممة . اكممارت الدراسممات انتممال الممى امكانيمممة الحفممول لمممى قممدرة كهربائيمممة اضمممافية لتعمممويس ممم ا النقفمممان ممممن خمممالل خنات الضممغط العممالي لميمماه تغ يممة لممق مسمم high pressure feed water)المرجمل heaters) ممممع مبممموت كتلمممة وموافممم ات البخمممار الخمممارل ممممن المرجمممل البخممماري حيمممث وجمممد انمممن باالمكمممان زيمممادة القمممدرة الكهربائيمممة مممن قممدرة الوحممدة العاملممة 1-11 % بنسممبة ]1,2[ . في الوقت الحاضر ال ي يعاني فين البلد ممن ازمممة حقيقيممة فممي تجهيممز الطاقممة الكهربائيممة نتيجممممة الممممنقص الكبيممممر فممممي انتممممال القممممدرة الكهربائيمة النماتج مممن قلمة المحطمات العاملممة والمم ي اليمةاضمافة المى ا ممال التخريمب المتو يممنعكب بفممورة مباكممرة لممى اقتفمماد وحيمماة ال ممرد العراقممي كممان البممد مممن دراسممة اسمملوب وليممد قمممدرة لممق مسممخنات الضمممغط العممالي لت كهربائية اضافية . تمميمير لممق مسممخنات ميمماه التغ يممة -0 لى اداع المحطات البخارية مسخنات مياه تغ ية المرجمل يمؤدي ان وجود بمممدون كممم المممى زيمممادة ك ممماعة المحطمممة ممممن خمممالل رفمممع درجمممة حمممرارة المممماع المممداخل المممى المرجممممممل وبالتممممممالي تقليممممممل كميممممممة الوقممممممود بنمماع ليممن تجهممز المفممروفة فممي المحطممة و جميمممع المحطمممات البخاريمممة بمسمممخنات ميممماه الضممغط الممواطل والضممغط تغ يممة المرجممل ات . ان لمممممق المسمممممخنات سممممموف ]3[العمممممالي ينعكب لى اداع المحطة بفورة اممة ممما يتطلب اخ بنظر اال تبار ه التيميرات نمد اجراع ه الدراسة وكما يلي : ين ار الممممممار بمممممر التممممموربضمممممغط البخممممم -أ البخاري يمممؤدي المممى الضمممغط العمممالي لمممق مسمممخنات زيادة كتلة البخار المارة بر مراحل التوربين ف المسمخن المغلمق والتمي بمدور ا الواقعة خلم تؤدي الممى زيممادة ضممغط البخممار المممار بممر سمم التممموربين . ممم ا بالتيكيمممد سممموف يمممؤدي المممى تغيممممر قمممميم ضممممغوط االسممممتنزاف للمسممممخنات ضح لتسخين وكما مو المتبقية وضغط ا ادة ا :]4[في المعادلة التالية 2226 / 2/ العدد 2 مجلة الخوارزمي الهندسية ,المجلد / حاتم فالح فاخر 1 )1.(.............................. 02 2 01 2 02 2 01 2       pp pp m m إن:حيث m .كتلة البخار المارة بر التوربين في حالة وجود مسخنات الضغط العالي m . كتلة البخار المارة بر التوربين في حالة لق مسخنات الضغط العالي 12 , oo pp الضغط العاليضغط البخار قبل مرحلة التوربين وبعد ا في حالة وجود مسخنات.  12 , oo ppضغط البخار قبل مرحلة التوربين وبعد ا في حالة لق مسخنات الضغط العالي. ان تغيير ضغوط االستنزاف فمي حالمة لمق مسمخنات الضمغط العمالي سمينعكب لمى كتلمة البخمار مستنزفة من المسخنات المتبقية والتي يتم تحديد ا ن طريق الموازنة الحرارية لكل مسخن. ال القدرة المنتجة -ب يمممؤدي لمممق المسمممخنات المممى زيمممادة القمممدرة المتولممدة مممن التمموربين البخمماري نتيجممة زيممادة الكتلممممة المممممارة بممممر المراحممممل الواقعممممة بعممممد المسمممخن المغلمممق والتمممي يمممتم حسمممابها كمممما : ]4[يلي   )2.(............................... hmp المرجل البخاري -ل يؤدي لق مسخنات مياه التغ ية المى بموط درجممممة حممممرارة الممممماع الممممداخل الممممى المرجممممل وبالتمممالي يمممؤدي المممى انخ ممماس درجمممة حمممرارة الغمممازات الخارجمممة ممممن المرجمممل ممممما يسمممبب . ]5[دة ك اعة المرجل البخاريزيا 2.02,05.01 )4.(...............................2 )3.....(...............................1    kk k k fwout out حيث ان  تمممممل الزيمممادة فمممي ك ممماعة المرجمممل نتيجة لق مسخنات مياه التغ ية . out التغيمممر فمممي درجمممة حمممرارة الغمممازات الخارجة . fw التغيممر فممي درجممة حممرارة ميمماه تغ يممة المرجل نتيجة لق المسخنات . االكممارة بممان انخ مماس درجممة حممرارة والبممد مممن ميمماه تغ يممة المرجممل سمموف تممؤدي الممى زيممادة الحمممل الحممراري فممي المرجممل البخمماري ويممؤدي فممروفة داخممل الممى زيممادة الطاقممة الحراريممة الم :]5[المرجل وكما يلي         )6......(.............................. .. )5(........................................ . ii b ii ri ii ro ii sr ii wi ii bsii b i b i ri i ro i sr i wi i bsi b hhmhhm q hhmhhm q       .مرجل معدل تدفق البخار الخارل من ال sm إن:حيث 2226 / 2/ العدد 2 مجلة الخوارزمي الهندسية ,المجلد / حاتم فالح فاخر 02 bh البخار الخارل من المرجل انمالبي. wih الداخل الى المرجل الماع انمالبي. srm معممدل تممدفق البخممار الممداخل الممى معيممد . ( reheater)التسخين roh البخمممممار الخممممممارل ممممممن معيممممممد انممممممالبي . التسخين ri h البخممممار الممممداخل الممممى معيممممد انمممممالبي .التسخين i جمممود جميمممع ممممل المحطمممة ممممع و حالمممة المسخنات . ii حالممة مممل المحطممة مممع لممق مسممخن واحد من مسخنات الضغط العالي و لين فمان : )7.........(..............................i b ii bb qqq  التغيمممر فمممي الطاقمممة الحراريمممة qحيمممث ان المفروفة في المرجل ند لق مسمخن ممن مسخنات مياه تغ ية المرجل ك اعة المحطة -د غيممر الحافممل فممي القممدرة المتولممدة والطاقممة الت الحراريممممة المفممممروفة سمممموف يممممنعكب لممممى ك اعة المحطة وكما يلي : )8.........(........................................ bq p  نتيجمممة المممى مممما ممممر كمممره ممممن تممميمير لغلمممق مسمممخنات ميممماه التغ يمممة لمممى اداع المحطمممة الحراريمممة فقمممد اجريمممت الكميمممر ممممن الدراسمممات حراريمممممة النظريمممممة والعمليمممممة لمممممى وحمممممدات مختل ممة السممعات واكممارت تلمم الدراسممات الممى ما يلي : * امنمماع لممق مسممخنات ميمماه تغ يممة المرجممل فممممان كممممل مممممن التمممموربين والمرجممممل البخمممماري اريمممة ات الحر يعممممالن بمممدون تجممماوز االجهممماد ]4,6,7,8,9,10,11,12,13[المسموح بها * لممق مسمممخنات الضمممغط العمممالي ال يسمممبب تغ ية المرجل من هدرجة حرارة مياانخ اس لعمممممل المرجممممل وكمممم ل الحممممد المسممممموح بممممن (deareater)يضممممن ممممل طمممارد الهمممواع ]4[ زيمممادة قمممدرة التوربينمممات البخاريمممة إمكانيممة* % ند لق مسخنات الضغط العالي بحمدود ]1,2[من القدرة المنتجة 11-6 مليمممممة لمممممق مسمممممخنات التغ يمممممة ال إن* ممكمممن و ة يتطلمممب اضمممافة اي مبمممال اضمممافي تطبيقممن بسممهولة حيممث ان جميممع التوربينممات البخارية مزودة بفممام لمق نمد كمل نقطمة استنزاف من خاللن ممكن لق مسمخن ميماه التغ ية وك ل وجود فمامات لى خط مياه ]4,14[ية ممكن من خاللن زل المسخنالتغ النتائج -3 تممممم اجممممراع الحسممممابات لممممى محطممممة الممممدورة كمكل mw 161ة البخارية البخارية للوحد ( فمممي حالمممة ملهممما بالحممممل التفمممميمي 1) (mw161 وك ل ند ملهما فمي الحممل ) ( 1( . يكممير الجممدول )mw110الجزئممي ) الممممى التغيممممر الحافممممل فممممي القممممدرة المتولممممدة 2226 / 2/ العدد 2 مجلة الخوارزمي الهندسية ,المجلد / حاتم فالح فاخر 01 (pوالقممممدرة الحراريممممة ) ( المفممممروفةq ) ريممة اضممافة الممى درجممة وك مماعة الوحممدة البخا حمممرارة المممماع المممداخل المممى المرجمممل . اجريمممت الحسابات للوحمدة البخاريمة فمي حالمة ملهما ممممع وجمممود جميمممع مسمممخنات الضمممغط العمممالي ومقارتممة لمم مممع ملهمما نممد لممق مسممخن واحممد مممن الضممغط العممالي ومممن مممم مسممخني ( 0)الضغط العالي ,فيمما يكمير الجمدول رقمم لمحطمة mw6171ة نتائج الوحمدة البخاريم ( فمي حالمة ملهما ممع 0جنوب بغداد كمكل ) وجمممممود جميمممممع مسمممممخنات الضمممممغط العمممممالي ومقارنتها مع لق مسخن واحد مم مسخنين ميمماه نغ يممة المرجممل . الوحممدة مممن مسممخنات لمحطة النافرية كمكل mw011البخارية ( تممم دراسممتها فممي حالممة ملهمما مممع وجممود 3) نتها ممع قار مو جميع مسخنات الضغط العالي لمق امنين وأخيرا مم من و واحد مسخن لق ( يكممممير الممممى 3) مالمممممة مسممممخنات والجممممدول نتائج ه الوحدة . اضافة الى ل فقد تمت مقارنة كمية الوقود الالزمة النتال ه القدرة االضافية من جراع لمممق مسمممخنات الضمممغط العمممالي ممممع كميمممة الوقممممود الالزمممممة النتممممال ن ممممب مممم ه القممممدرة ضمممافية فمممي حالمممة انتاجهممما ممممن مولمممدات اال ( و مو مما معممول بمن 31 % الديزل )بك اعة فمي جميمع ارجماع العمراق فمي الوقمت الحاضمر وقمممد اكمممارت النتمممائج المممى تركممميد اسمممتهال ا تمادا لمى سمعة 8-00الوقود بنسبة % وبافتراس استخدام ن مب النمو وحدة التوليد .من الوقود االستنتاجات -2 مممممن القممممدرة الكهربائيممممة األكبممممرالجممممزع -1 المنتجممة فممي العممراق يعممود الممى محطممات ( . 2بخارية كما يكير الجدول رقم ) اكارت النتائج الحالية الى امكانية زيادة -0 ممن قمدرة %11القدرة الكهربائية بحدود الوحدة العاملة و ا ما يتوافمق ممع كميمر من النتائج السابقة . ل يمؤدي لق مسمخنات ميماه تغ يمة مرجم -3 الممى انخ مماس درجممة حممرارة الممماع الممداخل مرجممل البخمماري وكانممت اقممل درجممة الممى ال والتي ي ضممن الحمدود c)o(155 ي المسمممموح بهممما لعممممل المراجمممل البخاريمممة . ]15[(bar 98)عاملة بضغط اكمر ال اسممممتنادا الممممى ظممممروف مممممل المحطممممات -2 البخارية فمي العمراق فمي الوقمت الحاضمر دام اسمملوب لممق ( فممان اسممتخ1جممدول ) مسمممخنات الضمممغط العمممالي سممموف يمممؤدي الى امكانية توليد قدرة كهربائيمة اضمافية hrs.2-3 بمعمدل mw 011بمقدار يوميمما مممما يمكمممن التغلممب لممى المممنقص الحافل في التوليد وخفوفا في اوقات اال طال . امكانيمممة اسمممتخدام ممم ا االسممملوب لمممى -1 جميمممع المحطمممات البخاريمممة العاملمممة فمممي 2226 / 2/ العدد 2 مجلة الخوارزمي الهندسية ,المجلد / حاتم فالح فاخر 06 راق وبدون تكبد فرف مبمال اضمافية الع كمما البمد ممن اخمم بنظمر اال تبمار ادخممال مم ا االسمملوب فممي المحطممات التممي سمميتم انكائها الحقا من خالل رفع درجة حمرارة الماع الداخل الى المرجل . تركميد اسممتهال فمرفيات الوقممود بنسممبة -6 مقارنممة مممع مولممدات الممديزل 00-8 % افة الممى العاملممة فممي الوقممت الحاضممر اضمم تجنمممب الكميمممر ممممن المخممماطر والمكممماكل الناتجة من التوزيمع والمربط يمر الممنظم من مولدات الديزل . 2226 / 2/ العدد 2 مجلة الخوارزمي الهندسية ,المجلد / حاتم فالح فاخر 06 mw 112و الحمل الجزئى mw 160(: محطة الدورة عند الحمل التصميمى 1جدول رقم ) t co η % ∆q mw ∆p mw heat supplied mw output power mw conditions load mw 240 40.5 366.7 161.4 with all heaters 162 190 39.9 44.6 (12%) 18.3 (11%) 411.3 179.7 without first heater 155 39.6 65.1 (17%) 25.5 (15%) 431.8 186.9 without first & second heaters 002 39.2 264.6 114.1 with all heaters 112 172 38.75 31 (11.7%) 11.5 (10%) 295.6 125.6 without first heater 111 38.5 37.6 (14.2%) 13.6 (11.9%) 302.2 127.7 without first & second heaters mw 67.5(: محطة جنوب بغداد عند الحمل التصميمى 0جدول رقم ) t co η % ∆q mw ∆p mw heat supplied mw output power mw conditions 234 33.2 178.6 69.0 with all heaters 195 32.3 43.8 (24%) 2.9 (4.2%) 192.3 71.9 without first heater 183 32.1 52 (29%) 4.138 (6%) 195.4 73.1 without first & second heaters 2226 / 2/ العدد 2 مجلة الخوارزمي الهندسية ,المجلد / حاتم فالح فاخر 01 mw 200(: محطة الناصرية عند الحمل التصميمى 3جدول رقم ) t co η % ∆q mw ∆p mw heat supplied mw output power mw condition 240 7207 459 203.2 with all heaters 220 72 28 (6.1%) 8.4 (4.1%) 487 211.6 without first heater 192 330. 55.2 (12.03%) 19.2 (9.5%) 514.2 222.4 without first & second 170 3303 79.2 (17.3%) 27.4 (13.4%) 538.2 230.6 without first , second & third heaters : المحطات البخارية فى العراق وسعاتها التصميمية*(7جدول رقم ) .0221لعام * بيانات الشركة العامة النتاج كهرباء الوسط سعة الوحدة الواحدة )ميكا واط( دد وحدات المحطة اسم المحطة الحرارية تسلسل 322 7 محطة كهرباء المسيب 1 022 6 محطة كهرباء بيجى 0 022 7 محطة كهرباء الناصرية 3 022و وحدتين بسعة 162وحدتين بسعة 7 محطة كهرباء الدورة 7 002 0 محطة كهرباء الهارثة 1 71و وحدة بسعة 67وحدتين بسعة 6 محطة كهرباء جنوب بغداد 6 122 0 محطة كهرباء النجيبية 7 11 0 محطة كهرباء الدبس . : المحطات البخارية فى العراق و قدرة انتاجها الحالية*(1جدول ) 2226 / 2/ العدد 2 مجلة الخوارزمي الهندسية ,المجلد / حاتم فالح فاخر 08 .0221* بيانات الشركة العامة النتاج كهرباء الوسط لعام عدد الوحدات اسم المحطة الحرارية تسلسل العاملة القدرة التى تنتجها الوحدة العاملة 022 7 محطة كهرباء المسيب 1 112-122 7 محطة كهرباء بيجى 0 022 3 محطة كهرباء الناصرية 3 71 0 محطة كهرباء الدورة 7 022 0 محطة كهرباء الهارثة 1 (6) الوحدة 31( و 1,0,7)الوحدة 32 7 محطة كهرباء جنوب بغداد 6 72 1 محطة كهرباء النجيبية 7 1 0 محطة كهرباء الدبس . ,kerelov, e. e., ivanov, a. m.,1978-1 المفادر.1 increasing the maneuverability of 2226 / 2/ العدد 2 مجلة الخوارزمي الهندسية ,المجلد / حاتم فالح فاخر 31 advanced power unit by the method of cutting-off hph, thermal engineering, no.12 ,p.66-69 (in russian translated to english). 2-leonkov, a. m., 1978, anayltic study of the possibility of maximum load on the boiler and unit during cutting-off hph, power generation, no.12, p.124-128 (in russian). 3-bezlbken, v. l., 1985, control the electric power of extraction turbines which are operate by heating load, thermal engineering, no.12, p.49-52 (in russian translated to english). 4-ivanov, v. a., 1986, regimes of high capacity steam power stations, leningrad, p. 248 (in russian). 5-shepbej, v. e., baobel, l. a. ,1981, computation variation of fuel and heat consumption during cutting-off high pressure heaters of extraction turbines, electric power station, no.9,p.38-41(in russian). 6-bezlbken, v. l., 1996, combinde steam-gas power plants and steam power plants, sankt-peterburg, p.295 (in russian). 7-ilen, e. t., pejenken, c. p., 2001, expansion the range of changing electric power of turbo-generator type t-110-130 during its operating by the heat load, vectnek,no.1 p. 5055 (in russian). 8ilen, e. t., pejenken, c. p., 1999, operating characteristic of turbogenerator type t-250/300-240 during working with cutting-off high pressure heaters and pay-pass heating water through heat water heater, vectnek, no.3, p.51-55 (in russian). 9-meshkaelov, c. e., ivanov, v. a., 1990, introduction new methods for increasing the range of control thermoelectric plants, electric power station, no.8, p.53-56 (in russian). 10-mekarjen, v. a., tajev, a. i., 2001, increasing the maneuverability of turbo-generator thermoelectric plants for their complicity during decreasing electric load, thermal engineering, no. 4, p. 37-42 (in russian translated to english). 11-zekov, c.a., mojan, c.e., 1996, control the expediency of receiving additional power in the units 3001000mw, thermal engineering, no.3, p.7-11 (in russian translated to english). 12zekov, c.a., peshenkov, v. e., 1967, study the possibility of forcing the boilers of high-capacity condensing units, thermal engineering, no.6, p.16-21 (in russian translated to english). 13-zekov, c.a., 1967, study the operation of power unit 200mw during cutting-off high pressure heaters, thermal engineering, no. 12, p.29-32 (in russian translated to english). 14-moshkaren, a. v.,devojken, m. a.,2002, analysis trend of development the heat power engineering in russia, ivanovo, p. 256 (in russian). 15-catalog of stationary steam boilers, types and basic parameters (3619-89) 1989. 2226 / 2/ العدد 2 مجلة الخوارزمي الهندسية ,المجلد / حاتم فالح فاخر 31 160mw 19 18 17 16 15 14 13 12 11 10 9 8765 21 2022 4 3 2 1 lps h.ps boiler fig. (1): the heat cycle of dura power plant 23 22 21 20 19 18 17 16 15 2 3 12 14 13 8 810 11 9 6 4 5 turbine 24 26 31 25 hot well condenser 2932 35 2893419 37 30 3942 43 13 boiler 1 46 44 27 36 33384041 45 fig. (2): the heat cycle of south baghdad power plant 2226 / 2/ العدد 2 مجلة الخوارزمي الهندسية ,المجلد / حاتم فالح فاخر 31 lps 321 boiler hps ips fig. (3): the heat cycle of nasria power plant lps 321 boiler hps ips 2226 / 2/ العدد 2 مجلة الخوارزمي الهندسية ,المجلد / حاتم فالح فاخر 30 a theoretical study for increasing production of electric power from iraqi steam power plants. abstract: this article conclude a theoretical study for the possibility to produce additional electric power from iraqi steam power plants by cutting – off high-pressure feed water heaters . three separated steam power plants which dura , south –baghdad and nasria were studied . the investigation showed the possibity of increasing the electric power from 10 to 15% for dura and nasria , whereas 6% for south – baghdad . according to the nowadays of operation to iraqi steam power plants , the results showed that by cutting–off high pressure feed water heaters we can generate additional electric power about 250 mw during 3-4 hrs. daily. in addition, the fuel consumption can be reduced in comparison with diesel generator, which is used to produce the same addional electric power. al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 3857 (2013) theoretical and practical investigation of blood flow through stenosed coronary lad artery sadiq j. abbass * furman k. ahmed ** zahraa a. mohammed *** * department of medical engineering / college of engineering / al-nahrain university ** department of engineering / nursing home hospital *** department of biomedical engineering /al-khwarizmi college of engineering / university of baghdad (received 14 february 2012; accepted 11 september 2013) abstract atherosclerosis is the most common causes of vascular diseases and it is associated with a restriction in the lumen of blood vessels. so; the study of blood flow in arteries is very important to understand the relation between hemodynamic characteristics of blood flow and the occurrence of atherosclerosis. looking for the physical factors and correlations that explain the phenomena of existence the atherosclerosis disease in the proximal site of lad artery in some people rather than others is achieved in this study by analysis data from coronary angiography as well as estimating the blood velocity from coronary angiography scans without having a required data on velocity by using some mathematical equations and physical laws. fifty-eight patients were included in this study that underwent cardiac catheterization for diagnostic coronary angiography. it found some information that may explain the ability of small arteries to develop the lesions with time mainly in proximal site of lad artery. for investigation the fluid-structural response to pulsatile newtonian and non-newtonian blood flow through an axisymmetric stenosed coronary artery; the theoretical simulation is built up by using ansys 11, to evaluate the biomechanical parameters in the atherosclerotic process. rigid and newtonian cases were investigated to provide an understanding on the effects of incorporating the fluid-structural interaction (fsi) into the model. for validation of the models and methods used, the computation results are compared with the previous studies. the non-newtonian carreau model was investigated with fsi, which showed a little difference in comparison with the newtonian flow model in terms of velocity, pressure, wall shear stress (wss), and stress distribution. keywords: blood flow, atherosclerosis, stenosed artery, simulation, modeling, coronary angiography. 1. introduction understanding of blood flow hemodynamics has great importance in testing the hypothesis of disease pathogenesis, assessment and diagnosis of the cardiovascular disease, vascular surgery planning, modeling the transport of drugs through the circulatory systems and determining their local concentrations, predicting the performance of cardiovascular equipments or instruments that have not yet been built such as heart valves, stents, probes, etc., and devising better therapies of mainly coronary artery occluding, atherosclerosis, thromboses, vacuities or varicose, aneurysms, etc. [1] recently there has been a significant amount of researches done on stenosed arteries; arteries that have blockage caused by a disease called atherosclerosis. the term arterial stenosis refers to the narrowing of an artery where the internal cross sectional area (lumen) of blood vessel reduces. in the atherosclerotic disease the certain cholesterols and other lipids are deposited beneath the intima (inner lining) of the arterial wall which is normally smooth to allow for easy transportation of red blood cells, oxygen white blood cell, nutrients, and other vital substances that the body required. as the amount of this fatty material increases there is an accompanying proliferation of connective tissue and the whole sadiq j. abbass al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 3857 (2013) 39 forms a thickened area in the vessel wall called plaque. [2] atherosclerosis can affect all large and medium-sized arteries, including the coronary, carotid, and cerebral arteries. risk factors for this disease include diabetes, cigarette smoking, family history, sedentary lifestyle and hypertension. [3] most of the studies available at present focus on the clinical aspects of the disease. there has been a great push, however, to understand the physics involved with the disease itself, including the cause and possible methods of treating it. the focusing on some of these physical factors for putting our hand on some individual properties that, directly or indirectly, may be have an influence on existing the atherosclerotic disease in some people rather the others and in some arteries rather the others, is the aims that this study wants to do. also, the computational techniques have demonstrated a strong ability in modeling flow behavior within stenosed arteries of varying geometries and conditions that can be specified according to realistic conditions.[4] in this study, the incorporation of two factors, i.e. non-newtonian blood flow and fsi (fluidstructural interaction) , is achieved to investigate the pulsatile flow behavior in stenosed artery as well as the structural response. 2. aims of study the stenosis in coronary arteries due to atherosclerotic disease may prevent the blood flow and causes a heart attack or death in its acute situation.[4] therefore it is very important to know how blood is flowing in the area of stenosis, then that will help doctors or surgeons to make a diagnosis or to make an operation plan. the proximal segment of lad artery is selected in this study for being a region of interest where atherosclerosis is likely to occur. the first aim of the work described in this paper is the investigation of the fluid structural response to pulsatile newtonian and non-newtonian blood flow through an axisymmetric stenosed vessel which has similar lad coronary artery dimensions by using the cfd (computational fluid dynamics) technique, for providing a basic understanding of atherosclerosis. among various constitutive equations, the non-newtonian carreau model is used to determine its nonnewtonian influence as well as the basic physical characteristics such as stresses. the second approach to investigate the blood flow in stenosed lad coronary artery is by performing the coronary angiography on real cases that were found at two hospitals in baghdad. however, in this way a qualitative assessment is made for understanding the physiological significance of disease and trying to estimate the blood velocity from coronary angiography scans without having the required data on velocity by using some mathematical equations and physical laws, as well as, looking for any other physical factors and correlations which explain the lesion in the proximal site of (lad). 3. angiographical investigation 3.1. the patients fifty-eight patients were included in this study and divided into two groups; group i: consisted of fifteen individuals; (4) females and (11) males who underwent cardiac catheterization for a typical chest pain and the diameter stenosis in proximal lad was less than 25%, so they were considered a control group. group ii: consisted of forty-three patients; (10) females and (33) males with the diameter stenosis of more than 25% in proximal lad. in the catheterization laboratory, the measurements were done by performing coronary angiography on the real cases found at two hospitals in baghdad, and by injecting a contrast medium; the cardiac coronary arteries were made visible on x-ray film. the main clinical characteristics of the patients enrolled in this study are summarized in table (1) and the comparison in risk factors between two groups is shown in the figure (1). sadiq j. abbass al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 3857 (2013) 40 table 1, patients’ clinical characteristics. characteristics group i (n = 15) group ii (n = 43) age, range (46 – 58) (54 –81) male sex, n (%) 11 (73) 33 (77) body weight (kg) 61.4 + 5.3 64 + 6.6 risk factors, n (%) family history 4 (27) 31 (72) diabetes 2 (13) 10 (23) smoking habits 4 (27) 29 (67) fig. 1. the comparison in risk factors between two groups. 3.2. statistical analyses and the obtained data statistical analysis in this study was done using spss 11.5 software. the statistical significance of difference in mean of a continuous dependent (normally distributed variable) between two groups was assessed by independent samples ttest. p values of ≤ 0.05 were statistically significant. in biological system the average is the value taken for the most numbers in the study and the standard deviation (±sd) reflects the range around the average. the reference diameters, cross section areas, and normal blood flow rate at the proximal site of (lad) for all patients were obtained from the angiograms are illustrated in table (2) and (3). table 2, values of diameters, cross section areas and flow rates of the proximal site of lad in groups (i & ii). group i mean ± sd (min – max) group ii mean ± sd(min – max) p value diameter (mm) 3.48 ± 0.30 (2.86 3.81) 3.26 ± 0.25 (2.63 3.78) 0.04* cross section area (mm 2 ) 10.00 ± 1.55 (6.43 – 11.5) 8.50 ± 1.38 (5.50 – 11.20) 0.04* flow rate (ml/s) 1.91 ± 0.31 (1.29 2.22) 1.72 ± 0.18 ( 1.10 – 1.98) 0.05* 0 10 20 30 40 50 60 70 80 family history diabetes smoking habits group ii group i sadiq j. abbass al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 3857 (2013) 41 table 3, the values of diameters, cross section areas, and flow rates of the proximal site of lad in (males & females) of groups (i & ii). males p value females p value group i mean ± sd group ii mean ± sd group i mean ± sd group ii mean ± sd diameter (mm) 3.53 ± 0.30 3.28 ± 0.26 0.033* 3.34 ± 0.21 3.29 ± 0.30 0.80 cross section area (mm 2 ) 9.87 ± 1.63 8.51 ± 1.40 0.030* 8.78 ± 1.17 8.53 ± 1.46 0.80 flow rate (ml/s) 1.97 ± 0.33 1.70 ± 0.28 0.034* 1.76 ± 0.24 1.72 ± 0.29 0.82 3.3. calculations and data collection there were many physical parameters involved in the study, they were based on the manual of the medical system existed in hospital. the measurements were done as follows: the reference (diameter in mm and cross section area in mm 2 ) and obstructed (diameter in mm and cross section area in mm 2 ) for the proximal segment of lad were calculated for each patient by the provided software. the cross section area calculation is based on the assumption of circular cross section at the obstruction and reference position. for abnormal patients, the lesion length (mm) was calculated by the provided software. the normal flow (ml/s) is calculated for each patient from the reference cross section area (cm 2 ) of the vessel and an assumed average flow velocity of (20 cm/s) by using the equation below: …(1)  symmetry index was given by the provided software. it grades a plaque area in term of its position around the internal wall of the artery on a 1.0 that means the plaque area is completely symmetric and 0.0 means the plaque area is totally eccentric. percentage diameters and area stenosis can be calculated by using the following equations: ( ) …(2) ( ) …(3) the value of ∆p was determined by the provided software, based on the fluid dynamic equations and validated in-vitro by young and invivo by gould: where: ∆p = pressure drop. cv=poiseuille resistance in function of stenotic length. ct = turbulence resistance in function of stenosis (experimental value). flow = (20 cm/s × reference area (cm 2 )) × sfr ratio  the sfr ratio means stenotic flow reserve. stenoses cause problems for flow because they dissipate pressure (waste energy) there by making less pressure available for pushing the flow through the downstream capillaries in the heart muscle. in the most clinical situations, the reduction of flow by the stenosis is relevant; however, the angiogram shows only the anatomy of a lesion. the bridge linking anatomy to functional severity is sfr.  depending on the physical properties of the blood and by using mathematical equations, it might calculated the most effective physical quantity in the location of the lesion site which is the blood velocity by using the equation (1) on the sfr ratio to find the actual flow we get: …(5) …(6) …(7) sadiq j. abbass al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 3857 (2013) 42 ( ) …(8) by using the assumed average flow velocity of (20 cm/s) to be as u1; and from equations (7) and (8) u2 will be calculated by the following equations: …(9) …(10) 3.4. correlations between the obtained parameters based on the obtained data, the following figures are drawn using the microsoft office excel 2007 software. fig. 2. the correlation between % area and % diameter stenosis. fig. 3. the correlation between % area stenosis and (∆p). fig. 4. the correlation between % diameter stenosis and velocity. fig. 5. the correlation between velocity and pressure drop. fig. 6. the correlation between % area and blood flow rate. y = 0.966x + 24.65 r² = 0.966 40 50 60 70 80 90 100 20 40 60 80 % a re a s te n o si s % diameter stenosis y = 0.330e0.055x r² = 0.743 0 10 20 30 40 50 60 70 80 30 50 70 90 p re ss u re d ro p ( ∆ p ) i n m m h g % area stenosis y = 1.537x0.943 r² = 0.958 0 20 40 60 80 100 120 20 30 40 50 60 70 80 v e lo ci ty ( cm / s) % diameter stenosis y = -0.023x2 + 2.524x + 15.17 r² = 0.645 35 45 55 65 75 85 0 20 40 60 v e lo ci ty ( cm / s) pressure drop (∆p) in mmhg y = -0,025x + 3,126 r² = 0,658 0 0.5 1 1.5 2 2.5 40 60 80 100 f lo w r a te ( m l/ s) % area stenosis sadiq j. abbass al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 3857 (2013) 43 fig. 7. the correlation between blood flow rate and pressure drop (∆p). fig. 8. the correlation between blood flow rate and velocity at lesion site. fig. 9. the correlation between lesion length and pressure drop. fig. 10. the correlation between symmetry index and % area stenosis. fig . 11. the correlation between % area stenosis and the sfr ratio. fig. 12. the correlation between sfr ratio and blood velocity at lesion site. y = 1,897e-0,01x r² = 0,558 0 20 40 60 80 0 0.5 1 1.5 2 2.5 p re ss u re d ro p ( ∆ p ) in m m h g flow rate (ml/s) y = 185,1x-1,24 r² = 0,656 0 0.5 1 1.5 2 2.5 35 55 75 95 fl o w r a te ( m l/ s) blood velocity (cm/s) y = 4.203e0.218x r² = 0.547 0 10 20 30 40 50 60 70 80 0 5 10 p re ss u re d ro p ( ∆ p ) in m m h g lesion length (mm) y = 0.989ln(x) 3.522 r² = 0.552 0 0.2 0.4 0.6 0.8 1 40 60 80 100 s y m m e tr y i n d e x % area stenosis y = -2,966x2 + 7,013x + 90,17 r² = 0,911 40 50 60 70 80 90 100 0 2 4 % a re a s te n o si s sfr ratio y = -0,000x2 0,000x + 5,511 r² = 0,828 0 1 2 3 4 5 6 30 50 70 90 s f r r a ti o blood velocty (cm/s) sadiq j. abbass al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 3857 (2013) 44 fig. 13. the correlation between sfr ratio and pressure drop (∆p). fig. 14. the correlation between % area stenosis and lesion length. fig. 15. the correlation between sfr ratio and blood velocity values by using equation (7) for all sfr value, blue and by using equation (9 and 10), red. 4. theoretical investigation 4.1. model geometry the geometry under investigation is shown in figure (16) which is similar to that used in simulation of griffith et al. [10], in shape and different in dimensions (i.e. the dimensions based on table (2) and (3) ) to be more accurate for the simulation of coronary artery. here; the selected dimensions are in agreement with dimensions of human (lad) artery, which is the artery under the study, that are taken from the obtained results in previous work. it consists of a long straight tube with an axisymmetric semicircular constriction. the stenosis degree is defined as: [10] ( ) …(11) where d1 is the internal diameter of the vessel and d2 is the diameter at the centre of the constriction. fig. 16. schematic diagram of the geometry used in this study. the internal diameter of the vessel, d1 is 3mm and the wall has a thickness of 0.5mm, giving an external diameter, d0 of 4mm. to achieve proper flow resolution for the simulation, the preand post-stenotic regions were chosen to be 3 and 10 diameters (i.e. 9 and 30 mm) long respectively. this will minimize the influence of the upstream and downstream boundary conditions and sufficiently capture the post-stenotic flow features. [9] figure (17) shows the mean velocity waveform of coronary blood flow with a 1.0sec period that was used as the inlet velocity conditions in the computational models. it is similar to that used in the simulation of dehlaghi et al. [3]. the severity of a stenosis or stenosis degree is determined by the amount of the cross sectional area that has been ‘blocked’ by the occlusion. for stenoses with varying geometry, the cross section is usually taken to be the narrowest portion (referred to as the ‘throat’) of the blockage. y = 0,000x2 0,067x + 5,125 r² = 0,667 0 1 2 3 4 5 6 0 20 40 60 80 s f r r a ti o pressure drop (∆p) in mmhg 40 50 60 70 80 90 100 0 5 10% a re a s te n o si s lesion length (mm) y = -2,579x2 + 2,541x + 88,70 r² = 0,861 y = -194ln(x) + 343,2 r² = 0,942 35 135 235 335 435 0 1 2 3 4 5 v e lo ci ty ( cm / s) sfr ratio sadiq j. abbass al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 3857 (2013) 45 in this study it will be 56%; that means d2 is 2mm in equation (11) and the length of the stenotic portion, l is set to be 1mm that is in agreement with that obtained from angiographical investigation. fig. 17. physiological waveform of pulsatile coronary blood flow that is used as inlet velocity of all models. 4.2. boundary conditions for the fluid model, the vessel walls are assumed to have a no-slip boundary condition applied. vessel porosity is also ignored; therefore fluid is assumed not to penetrate through the walls as it flows along the vessel. therefore, the boundary conditions applied to the vessel walls are: …(12) along the line axis of symmetry, there is to be no change of velocity in the radial direction, effectively reducing the radial component of the velocity to be zero. therefore, the boundary condition applied is: …(13) for validation with literature, a parabolic velocity profile corresponding to a fully developed poiseuille flow for a newtonian uncompressible flow through a circular tube was specified. this profile varies with time according to the waveform specified in figure (20). the maximum velocity umax(t) of the parabolic profile corresponding to the appropriate flow is equal to two times the mean velocity of the parabolic profile, umean(t), for laminar flow within a circular tube, i.e.: due to the changes in viscosity with shear rates, each newtonian and nonnewtonian model will have different fully developed velocity profiles, which can affect the flow behavior significantly about the stenosis. [10] for the outlet of the flow model, a constant pressure of 4140 pa was set for all models. this value was chosen to be as that used by chan et al. simulation [7]. the solid model corresponding to the vessel walls is assumed to be fixed at the ends such that only movement in the radial-tangential plane is allowed. the outer surface of the vessel is assumed to be at the equilibrium pressure of 0 pa, which allowed the vessel wall to distend or contract accordingly based on the pressure distributions within. for the inner surface of the vessel, the fluid pressure will be applied to deform the structure. 4.3. formulation of the problem this study will investigate the effects of implementing non-newtonian models for blood flow as well as having the wall deform following the fsi iterative process. it is important to provide several comparative studies between these factors by comparing fluid properties such as the wall shear stress (wss), pressure distribution and flow velocity and viscosity distributions. in addition, several simulations need to be run to provide comparison with available literature to determine if the geometry used, the fluid and solid model settings and the fsi method implemented are accurate. to achieve this validation, there will be one case run: newtonian pulsatile flow through a rigid wall (model i). then; the investigation of pulsatile newtonian flow through a compliant (fsi-enabled) wall (model ii) is used. and the investigation of pulsatile non-newtonian flow through the geometry incorporating fsi: carreau model (model iii) is used to determine the effect of the change in viscosity on the flow behavior. 4.3.1. rigid newtonian model (model i) in this simulation the fluid was assumed to be incompressible, meaning the density is set to remain constant, and newtonian. the vessel wall is set to be non-deformable. pulsatile flow was specified at the inlet as the waveform which is shown in figure (17). the velocity profile used for the inlet of this model was a fully developed laminar profile, as mentioned previously. this one cardiac cycle velocity (cm/s) sadiq j. abbass al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 3857 (2013) 46 allowed the model settings to be similar to that used by mittal et al. [5] the fluid was set to have a density of 1050 kg/m 3 and a constant viscosity of 0.00345 n.s/m 2 . also, the maximum and minimum reynolds numbers (re) of the model were to be between (760 and 160) respectively. because of this low reynolds number and the relatively mild stenosis of the geometry, the flow was assumed to be laminar and reasonably axisymmetrical. for the fluid properties mentioned for this model and the boundary condition, the womersley parameter for a 3mm diameter tube has a value of 3.65. 4.3.2. fsi newtonian model (model ii) this model took into consideration the structural response to the flow properties of model i. therefore the solid model requires definitions to allow the response to be as realistic as possible. since this model is also used to provide comparisons to literature results which in turn will validate the fsi iterative scheme and solid-model solver, therefore, the vessel was considered to be incompressible, isotropic and linearly elastic, with a young’s modulus of 500 kpa, a poisson ratio of 0.499 and a density of 1000 kg/m 3 like the one used by chan et al. [7] the geometry used has been extensively discussed in section 4.1, whereas the equations of motion for an elastic solid are given in section 4.2. ideally, the vessel wall should be modeled as a hyperelastic material, which is the behavior of real tissue. [9] due to the fact that small deformations are expected, however, and for solver economy, the solid model was assumed to be isotropic elastic for fsi simulations. the fluid model used was exactly as in the case for model i. as described in the fsi iterative scheme, the flow will determine the deformation of the solid model, which in turn affects the shape flow path within the vessel. 4.3.3. fsi carreau model (model iii) for this model, the geometry used will be the same as that in model ii, where the solid model conditions are kept the same i.e. isotropic elastic. the fluid model is adjusted that it has same density of 1050 kg/m 3 with new value of viscosity by using carreau equation to specify the shear rate versus the apparent viscosity, and the rate that the axial velocity rises as one moves from the vessel wall toward the center. as the carreau equation is for non-newtonian fluids that exhibit shear thinning, the equation that describes the viscosity – strain rate ̇ , is as shown below, with the viscosity μ, given in poise, p (where 1 p = 0.1 n.s/m2). [8] [ ̇ ] ⁄ …(14) where, λ = 3.313 s, n = 0.3568, zero strain viscosity (i.e. resting viscosity), μ0 = 0.56 p and infinite strain viscosity, μ = 0.0345 p. 4.4. the simulation results the selected five regions represented in figure (18-a) illustrate the critical node locations corresponding to ip, bs, ms, as, and op, that have node numbers of 247, 232, 216, 6, and 195 respectively. the four different times represented in figure (18-b) illustrate the different phases of the cardiac cycle: minimum systole flow (t1), acceleration phase (t2), peak diastole (t3), and deceleration phase (t4). fig. 18a. model geometry showing the fluid (blue) the solid (pink) models and the mesh about the stenotic region as well as the critical node locations corresponding to the inlet and outlet, points (ip) and (op) respectively, the pre-stenotic region (bs), the mid-stenotic region (ms) and post-stenotic region (as). sadiq j. abbass al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 3857 (2013) 47 fig. 18b. the input axial velocity waveform for all coronary artery models with four selected times; 0.25 s (t1), 0.40 s (t2), 0.60 s (t3), 0.80 s (t4). 4.4.1. ( model i ) results  centerline axial velocity the centerline axial velocity waveforms for model i in the selected five positions are shown in figure (19). fig. 19. the centerline axial velocity waveforms for coronary artery model i with respect to time. the values of the centerline axial velocity in the selected five points at the selected four times are listed in table (4). table 4, the values of the centerline axial velocity for coronary artery model i in the selected five points at the selected four times. point position values of centerline axial velocity (cm/s) t1 t2 t3 t4 ip 3.000 9.000 15.500 10.000 bs 4. 753 18.293 33.391 23.136 ms 8.368 23.594 41.590 28.590 as 8.270 23.906 44.261 30.545 op 4.867 14.967 29.106 20.720  axial velocity profile the axial velocity profiles were obtained in three sites; bs, ms, and as at the selected four times and are shown in figure (20). fig. 20. the axial velocity profiles for model i in bs, ms, and as at t1 (a), t2 (b), t3 (c), and t4 (d). 1 0 .05 .1 .15 .2 .25 .3 .35 .4 .45 .5 valu 0 .1 .2 .3 .4 .5 .6 .7 .8 .9 1 time feb 14 2010 09:31:03 post26 ip bs ms as op sadiq j. abbass al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 3857 (2013) 48  the recirculation flow regions for model i;the recirculation region and its variation with time are shown in figure (21). fig. 21. the recirculation flow regions of model i in t1 (a), t2 (b), t3 (c), and t4 (d).  pressure gradient the pressure gradient in the selected four times with respect to axial distant for model i is shown in figure (22). fig. 22. the pressure gradient of model i at t1 (blue), t2 (red), t3 (violet), and t4 (green). at time t3; i.e. at 0.60 sec, the maximum value of the pressure drop is appeared. the pressure values in the five selected points at t3 are listed in table (5). table 5, the values of pressure for model i in the five selected points at t3. point position values of pressure (pa) ip 4316.9 bs 4277.7 ms 4212.6 as 4224.2 op 4140.0 4.4.2. ( model ii ) results  centerline axial velocity the centerline axial velocity waveforms in the selected five positions for model ii are shown in figure (23). fig. 23. the centerline axial velocity waveforms for coronary artery model ii with respect to time. 1 4140 4158.6 4177.2 4195.8 4214.4 4233 4251.6 4270.2 4288.8 4307.4 4326.003 0 .68 1.36 2.04 2.72 3.4 4.08 4.76 5.44 6.12 6.8 dist (x10**-2) feb 16 2010 17:12:20 post1 time=.25 path plot nod1=247 nod2=2 pres0.8 pres0.6 pres0.4 pres0.25 1 0 .05 .1 .15 .2 .25 .3 .35 .4 .45 .5 valu 0 .1 .2 .3 .4 .5 .6 .7 .8 .9 1 time post26 ip bs ms as op stenosis region sadiq j. abbass al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 3857 (2013) 49 the values of the centerline axial velocity in the selected five points at the selected four times are listed in table (6). table 6, the values of the centerline axial velocity for coronary artery model ii in the selected five points at the selected four times. point position values of centerline axial velocity (cm/s) t1 t2 t3 t4 ip 3.000 9.000 15.500 10.000 bs 6.852 17.348 32.718 24.220 ms 8. 769 22.590 40.690 29.648 as 6.874 19.623 42.671 32.704 op 4.932 13.785 27.846 21.621  axial velocity profile the axial velocity profiles were obtained in three sites; bs, ms, and as at the selected four times and are shown in figure (24). fig. 24. the axial velocity profiles for model ii in bs, ms, and as at t1 (a), t2 (b), t3 (c), and t4 (d).  the recirculation flow regions for model ii; the recirculation flow region and its variation with time is shown in figure (25) fig. 25. the vector plot of recirculation flow regions for model ii at; t1 (a), t2 (b), t3 (c), and t4 (d).  pressure gradient the pressure gradient with respect to axial distant in the selected four times for model ii is shown in figure (26). sadiq j. abbass al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 3857 (2013) 50 fig. 26. the pressure gradient for model ii at t1 (blue), t2 (red), t3 (violet), and t4 (green). at time t3; i.e. at 0.60 sec, the maximum value of the pressure drop is appeared. the pressure values in the five selected points at t3 are listed in table (6). table 6, the pressure values for model ii in the five selected points at t3. point position values of pressure (pa) ip 4336.8 bs 4295.5 ms 4238.9 as 4252.8 op 4140.0  wall shear stress (wss) the wall shear stresses in the stenosis site at the selected four times are shown in figure (27). fig. 27. the contours of wall shear stress distribution for model ii at; t1 (a), t2 (b), t3 (c), and t4 (d). 4140 4168.316 4196.632 4224.948 4253.264 4281.58 4309.896 4338.212 4366.528 4394.844 4423.16 0 .68 1.36 2.04 2.72 3.4 4.08 4.76 5.44 6.12 6.8 dist (x10**-2) pres0.8 pres0.6 pres0.4 pres0.25 stenosis region sadiq j. abbass al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 3857 (2013) 51  wall stress distributions the wall stresses (radial, axial, and circumferential) in the stenosis site at the selected four times are shown in figure (28). fig. 28. the contours of wall stress distribution (radial, axial, and circumferential) for model ii at; t1 (a), t2 (b), t3 (c), and t4 (d). 4.4.3. ( model iii ) results  flow viscosity distribution the flow viscosity distributions at four instances within one phase of the fluid flow are plotted in figure (29). fig. 29. the flow viscosity distributions for model iii at t1 (a), t2 (b), t3 (c), and t4 (d).  centerline axial velocity the centerline axial velocity waveforms in the selected five positions for model iii are shown in figure (30). fig. 30. the waveforms of the centerline axial velocity in coronary artery model iii with respect to time. the values of the centerline axial velocity in the selected five points at the selected four times are listed in table (5). 1 0 .05 .1 .15 .2 .25 .3 .35 .4 .45 .5 valu 0 .1 .2 .3 .4 .5 .6 .7 .8 .9 1 time feb 10 2010 16:26:51 post26 ip bs ms as op sadiq j. abbass al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 3857 (2013) 52 table 5, the values of the centerline axial velocity for coronary artery model iii in the selected five points at the selected four times. point position values of centerline axial velocity (cm/s) t1 t2 t3 t4 ip 3.000 9.000 15.500 10.000 bs 6.773 17.487 33.110 22.875 ms 8.605 23.314 41.802 28.536 as 6.714 22.258 43.812 30.299 op 3.876 12.578 27.821 19.469  axial velocity profile the axial velocity profiles were obtained in three sites; bs, ms, and as at the selected four times and are shown in figure (31). fig. 31. the axial velocity profiles in bs, ms, and as for model iii at t1 (a), t2 (b), t3 (c), and t4 (d).  the recirculation flow regions for model iii; the flow recirculation regions and its variation with time are shown in figure (32). fig. 32. the recirculation flow regions of model iii in t1 (a), t2 (b), t3 (c), and t4 (d).  pressure gradient the pressure gradient with respect to axial distance in the selected four times for model iii is shown in figure (33). sadiq j. abbass al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 3857 (2013) 53 fig. 33. the pressure gradient for model iii at t1 (blue), t2 (red), t3 (violet), and t4 (green). at time t3; i.e. at 0.60 sec, the maximum value of the pressure drop is appeared. the pressure values in the five selected points at t3 are listed in table (6). table 6, the pressure values for model iii in the selected five points at t3. point position values of pressure (pa) ip 4335.3 bs 4297.4 ms 4229.6 as 4241.4 op 4140.0  wall shear stress (wss) the wall shear stresses in the stenosis site for model iii at the selected four times are shown in figure (34). fig. 34. the contours of wall shear stress distribution for model iii at t1 (a), t2 (b), t3 (c), and t4 (d).  wall stress distributions the wall stresses (radial, axial, and circumferential) in the stenosis site at the selected four times are shown in figure (35). 1 4140 4162.908 4185.816 4208.724 4231.632 4254.54 4277.448 4300.356 4323.264 4346.172 4369.079 0 .68 1.36 2.04 2.72 3.4 4.08 4.76 5.44 6.12 6.8 dist (x10**-2) pres0.8 pres0.6 pres0.4 pres0.25 stenosis region sadiq j. abbass al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 3857 (2013) 54 fig. 35. the contours of wall stress distribution (radial, axial, and circumferential) for model iii at; t1 (a), t2 (b), t3 (c), and t4 (d). 5. conclusions this study provides some understanding of blood flow characteristics in stenosed artery generally; and in stenosed lad coronary artery especially when it is affected by atherosclerotic disease. 5.1. conclusion from the angiographic data the reference diameters of the proximal site of lad decreases reflecting that the artery is affected with by than 25% diameter reduction was ready to accept the lesions anatomically. the cross-section area as a result for a decrease in diameters is affected more. a good correlation between % area and diameter stenosis indicates that we can use any of the two quantities to estimate the reduction in the ability of the lad to achieve its function in supplying blood to most of the anterior part of the heart. a positive correlation between pressure drop and % area stenosis indicating a relation which leads to the effect of the pressure drop on the % area stenosis. the relation between the pressure drop and the velocity which is calculated at the lesion site is strong enough to the degree that it affects the flow through the stenosis and cause in a reduction in the amount of blood provided along the rest of the lad. the sex of subjects has no significant effect on proximal segment of lad diameters, the cross sectional areas and the blood flow rates. the length of the lesion has no influence on the degree of severity of the atherosclerosis disease. the estimated value of velocity which is by using equation (10) is more satisfying to be closer to real value. 5.2. conclusion from the computational simulation there are several discrepancies that arise from the limitations of the program, but these do not affect on the overall conclusions. the comparisons between rigid (model i) and fsi (model ii) show a notable difference between the two models, which is that the pressures exerted by the fluid tend to increase the crosssectional area of the flow, which affectively slows the centerline fluid velocity. the increase in vessel radius also enhances the expansion from the stenosed portion to the non-stenosed region, which increases the flow recirculation occurring post-stenosis. the axial velocity profile for the carreau model (model iii) shows similar behavior to that of the model ii. the viscosity distributions for the carreau model show significant non-newtonian effects occurring about the axis of symmetry, particularly in the pre-stenosis region and in the immediate post-stenosis region, as well as in the wall region immediately post-stenosis where recirculation occurs. this study has produced high wall stress concentrations about the shoulders of the stenosis and the highest stress occurs in the post-stenosis shoulder that provides an insight into the regions where vessel wall rupture is most likely to occur. the stenosis itself does not indicate high stresses due to the stiffness of the region. aside from the sadiq j. abbass al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 3857 (2013) 55 shoulders of the stenosis, the ends of the vessel have the largest deformation, which therefore produces significant stresses. the pressure distributions for all the models show a constant drop in the pre-stenosis region followed by a sharp drop in the stenosed region which then increases when the flow region expands and is then followed by another pressure drop in the post-stenotic region. during the deceleration phase, though, there is a tendency for an adverse pressure to occur across the vessel. the carreau model tends to show higher pressure variations from the inlet to the outlet throughout the flow phase than fsi newtonian model. however, the sharp pressure drop at the stenosed region does not vary between the models and it is a function of the geometry. in the immediate poststenotic region, however, several different pressure characteristics can be noted between the models, such as the pressure rise in the immediate post-stenotic region. the wall shear stress distributions for all models are similar. the wall shear stress for the carreau model tended to have a slightly higher magnitude than the newtonian model due to the higher viscosity near the vessel wall. in the poststenosis region the large viscosities in the recirculation regions allow for a higher wall shear stress. overall, the wall shear stress distributions show similar trends to the newtonian model, suggesting that the shape is a function of the geometry whereas the magnitudes vary between models. it is noted that fsi has an important role in blood flow in stenotic arteries. therefore, an accurate description of the magnitude and variation in the wss is useful for detecting the early stages of vascular lesions 6. comparison with literature and experimental results as the first step of analysis of the results, the present numerical computations must be validated with the several experimental and analytical solutions with comparable unsteady laminar flows in constricted tube. the aim of this was to establish the validity of the code and settings used in the study as well as to provide an understanding of the effects of incorporating fsi into the simulation. the numerical results derived from this study were found to be in a significant agreement with that found by mittal [5] who use the same geometry shape and chan [7] who use the same assumptions. there is a slight difference with the experimental results obtained by giddens and ahmed [13] and [14]; but at all the results remain consistent. this could be due to experimental conditions influencing the results, such as gravity, reading errors and model imperfections as a result of the manufacturing process. the results of this study, however, have are similar to results of chan [7] and mittal [5]; therefore a similar conclusion can be made. the centerline axial velocity and axial velocity profiles of the study show strong agreement with the results of chan [7] and mittal [5] for both the rigid and fsi models. this, once more, validates the model and settings used for the study for both cases. about wall shear stress the fsi model shows a trend of under predicting the wall shear stress where as the rigid model tends to over predict the wall shear stress. but in spite of that the magnitudes may differ from literature, the trends are notably similar and indicate that peak wall shear stresses occur at the prethroat of the stenosis and vary with the flow rate. the stress distributions are similar to the results from literature. however, this study has produced high stress concentrations about the shoulders of the stenosis which is in agreement with the thick-wall theory for internally loaded pressure vessels and the highest stress shown in this study occurs in the post-stenosis shoulder. in the comparison with literature, this is viewed as the most significant stress generated within the model. the overall conclusion that can be derived from the results is that there is a good agreement between the works of this study and the previous studies, both numerical and experimental, thus validating the geometry and methods used. 7. referenes [1] f. yilmaz and m. gundogdu (a critical review on blood flow in large arteries; relevance to blood rheology, viscosity models, and physiologic condition). koreaaustralia rheology journal, vol. 20 (4), pp. 197-211. [december 2008]. [2] m. molla and c. paul (les of physiological pulsatile flow in a model arterial stenosis). bsme-asme international conference on thermal engineering, vol.4, pp. 27-29. dhaka, bangladesh. [december 2008]. [3] v. dehlaghi, s. najarian and m. tafazzolishadpour (effect of stent geometry on sadiq j. abbass al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 3857 (2013) 56 phase shift between pressure and flow waveforms in stented human coronary artery). american journal of applied sciences, vol. 5(4), pp. 340-446. [2008] [4] safoora karimi et al ( simulation of pulsatile blood flow through stenotic artery considering different blood rheologies). biomedical eng. applications, basis and communication, vol.25,[2013]. [5] r. mittal, s. simmons and f. najjar (numerical study of pulsatile flow in a constricted channel). fluid mechanics journal, vol. 485, pp. 337-378. cambridge university press. [2003] [6] w. chan, y. ding and j. tu (modeling of non-newtonian blood flow through a stenosed artery incorporating fluidstructure interaction). anziam journal, vol. 47, pp.c507-c523. emac. [2007] [7] b. johnston, p. johnston, s. corney and d. kilpatrick (non-newtonian blood flow in human right coronary arteries: steady state simulations). journal of biomechanics, vol.37, pp. 709-720. [2004] [8] hye, md. abdul ( simulation of transient blood flow in models of arterial stenosis and aneurysm), phd thesis, university of glasgow, [2012]. [9] m. griffith, t. leweke, m. thompson and k. hourigan (steady inlet flow in stenotic geometries: convective and absolute instabilities). fluid mechanics journal, vol. 616, pp. 111–133. [2008]. [10] j.d. bronzino, s.m. blanchard, and j.d. enderle (introduction to biomedical engineering). elsevier academic. [2005]. [11] d. kwak (cfd-mature technology?). nasa ames research center. nasa advanced supercomputing (nas) division, applications branch. [2006]. [12] d. giddens and s. ahmed ( velocity measurements in steady flow through axisymmetric stenoses at moderate reynolds numbers ). biomechanics journal, vol. 16, pp. 505–516. [1993] [13] d. giddens and s. ahmed ( pulsatile poststenotic flow studies with laser doppler anemometry ). biomechanics journal, vol.17, pp.695–705. [1994]. (2013) 3857 ، صفحة3، العدد9مجلة الخوارزمي الهندسية المجلد صادق جعفر عباس 57 المتضيقدراسة نظرية و عملية لجريان الدم في الشريان القلبي صادق جعفر عباس * فرمان قسيم أحمد ** زهراء عبد الرحمن محمد *** جامعة النهرين / كلية الهندسة / قسم الهندسة الطبية* مستشفى دار التمريض /قسم الهندسة** جامعة بغداد /الهندسة الخوارزمي كلية / قسم هندسة الطب الحياتي*** الخالصة ( من أهم األمراض التي تصيب األوعية الدموية وأكثرها شيوعا حيث يسبب تضيق atherosclerosisالعصيدي الدهني وأسمه العلمي )يعتبر التصلب ريان ص الديناميكية لجفي المساحة الداخلية للوعاء الدموي، لذلك فإن دراسة جريان الدم في الشرايين له من األهمية الالزمة لجعلنا نفهم العالقة بين الخصائ الدم و ظهور هذا المرض في الشرايين الدموية. computational ) fluid ناميكية الموائع تسمىفي هذه الدراسة ، قد تم استخدام طريقة حسابية تدخل ضمن تقنية واسعة تختص بدراسة دي dynamics العلمي النازل األيسر ومختصره( وذلك من اجل دراسة جريان الدم في أحد الشرايين التاجية وهو الشريان األمامي ( lad coronary artery بإصابتها لهذا المرضالقريبة من منشأ الشريان لتكون قيد الدراسة باعتبارها من أكثر المناطق شيوعاً المعروفة ى( حيث تم اختيار المنطقة األول . تضيق متماثل مستخدمين لدم المتذبذب أثناء مروره في شريان تاجي ذيلقد تم فحص تأثير نسيج الغشاء الوعائي وطبيعة السائل الدموي على جريان ا من اجل توفير مفهوم أساسي للعوامل البايوميكانيكة المرتبطة بعملية تكون مرض التصلب في الشريان. ansys 11برنامج موديل اقرب للواقع وأيضا لتحقيق هدف آخر للدراسة و هو معلومات عن الشريان التاجي قيد الدراسة تفيدنا في رسم ومن أجل إيجاد أبعاد حقيقية و بعض األشخاص أكثر البحث عن العوامل الفيزيائية وعالقاتها المتبادلة التي قد تفسر ظاهرة وجود هذا المرض في الشريان التاجي األمامي النازل األيسر في مريضاً كانوا قد أحيلوا ألجراء عملية القسطرة التشخيصية للشرايين التاجية في 58من غيرهم فقد تم تحليل نتائج معينة يظهرها جهاز القسطرة لحوالي % وذلك في المنطقة األولى من 55منهم كانت نتائج الفحص لديهم قد دلت على وجود تضيق في القطر لديهم بنسبة أكثر من 34مستشفيين في بغداد، % لذلك تم اعتبارهم 55الدراسة أما بقية الحاالت فكانت نتائجهم دالة على وجود تضييق بنسبة أقل من الشريان التاجي األمامي النازل األيسر، المنطقة قيد مجموعة قياسية لتحقيق المقارنة مع المجموعة األخرى. ي من الالزم توفرها في حساب وقد حاولنا استنباط قيم تقريبية لسرعة الدم من خالل هذا التحليل للمعلومات المأخوذة من جهاز القسطرة بعيدة عن تلك الت السرعة و من خالل عدة معادالت رياضية وقوانين فيزيائية خاصة. paper 61 dr. walid a. mahmoud/al-khwarizmi engineering journal ,vol.1, no. 2,pp 46-51 (2005) al-khwarizmi engineering journal al-khwarizmi engineering journal, vol.1, no.2,pp 46-51, (2005) fpga realization of two-dimensional wavelet and wavelet packet transform abstract: the field programmable gate array (fpga) approach is the most recent category, which takes the place in the implementation of most of the digital signal processing (dsp) applications. it had proved the capability to handle such problems and supports all the necessary needs like scalability, speed, size, cost, and efficiency. in this paper a new proposed circuit design is implemented for the evaluation of the coefficients of the two-dimensional wavelet transform (wt) and wavelet packet transform (wpt) using fpga is provided. in this implementation the evaluations of the wt & wpt coefficients are depending upon filter tree decomposition using the 2-d discrete convolution algorithm. this implementation was achieved using an fpga kit after building the logical circuits on the specified kit that uses the spartan-iie electronic library type implemented using the xilinx foundation series 2.1i software. key words: fpga, wavelet transform, wavelet packet transform. 1: -introduction: in the last few years, the wavelet analysis has take a place in the analysis field and has proved its strength and qualification for handling wide spectrum jobs, specially in the fields of speech and image processing. the wavelet transform (wt) & the wavelet packet transform (wpt) are one of the most powerful tools in the digital signal processing field which work as an analyzing tool for the decomposition of the input signals to evaluate the information carried by the dr. walid a. mahmoud electrical engineering dept. college of engineering university of baghdad dr. mohammed n. al-turfi computer and software engineering dept. college of engineering university of al-mustansirya dr. walid a. mahmoud/al-khwarizmi engineering journal ,vol.1, no. 2,pp 46-51 (2005) signal. and since it provides a representation of time against frequency against magnitude, therefore the frequency component can be evaluated at any specific time with high accuracy. for this reason the wavelet coefficients must be evaluated as accurate, as fast, as easy as possible which represents a problem [1,2]. the fpga technology was the solution for this problem, because it provides the necessary needs to over come these difficulties because of its high performance capabilities. the last ten years, all the companies that deals with electronic devices productions were in a race with each others and time to be the initiative in the fpga production field, because of the new word needs for this type of technology. recently, field programmable gate arrays have enjoyed widespread use due to several advantages related to relatively high gate density, short design cycle, and low cost. they can be used in all applications that currently use small – scale integrated circuits (ssi), medium– scale integrated circuits (msi), large scale integrated circuits (lsi), and programmable logic devices (plds). they also replace mask – programmable gate array (mpgas) in many applications that are limited to 10000 gates and they do not need a very high operational speed. because of the small number of coefficients that produced by the wavelet transform and their effectiveness, therefore these coefficients where very elegant and suitable to be implemented using the fpga. and since the wt minimize the amount of the processes on the data in order to obtain the needed coefficients therefore it reduces the processing time. which leads to reduce complexity, cost, size, and power consumption [2,3,4]. in this paper a new circuit design is dedicated which is suitable for calculating the two-dimensional wavelet transforms coefficients depending upon the decomposition of multi-resolution algorithm using the convolution approach in the representation of the finite impulse response (fir) filters while implementing the wavelet transform decomposition tree. this approach is used first because of the easiness in representation and implementation. second because of its perfectness in reconstructing the signal after its decomposition when applying inverse two-dimensional wavelet transform. third because this approach is very suitable for communication systems dr. walid a. mahmoud/al-khwarizmi engineering journal ,vol.1, no. 2,pp 46-51 (2005) because the filters in side the decomposition or reconstruction tree may be used to reduce noise or performing other processes while evaluating the coefficients of the wt and wpt [5,6]. this circuit can operate in a high speed (operating frequency is 1ghz). short processing time, and high accuracy (16,32,64 bit for the data and one sign bit), receiving data in many ways whether its serial or parallel and produce data in serial or parallel which made the circuit can be used for general purposes easily. an example and experimental results that has been obtained from the processor is given and shown in this paper with circuit block diagrams to show the data flow and results on the circuit. dr. walid a. mahmoud/al-khwarizmi engineering journal ,vol.1, no. 2,pp 46-51 (2005) sc al e (f re qu en cy ) time fig. (1): -the time – scale representation in the wavelet plane 2: -two dimensional wavelet & wavelet packet transform: in practical, the wavelet transform is of interest for the analysis of the nonstationary signals because it provides an alternative to the classical short time fourier transform (stft). for some applications its desirable to see the wave let transform as a signal decomposition onto a set of basis functions in fact basis functions called wavelets always under lie the wavelet analysis. they are obtained from the same prototype wavelet called mother function by dilation and contraction (scaling) as well as shifting. though the prototype wavelet can be of as a band pass filter (bpf) of constant quality factor (q property) of the other bpfs (wavelets) follows because they are scaled versions of the prototype. so, the notion of scale introduced in wt represents an alternative to frequency, leading to so call time – scale representation where this means that the signal is mapped in the time scale plain [5,6,7]. the fourier transforms and hence the stft use the sine and cosine as basis functions for analyzing since they are orthogonal (there is no correlation between them). the same must be applied in wt, which means that we are in need for the basis functions, which they must be orthogonal. and one more condition must be applied. the orthonormality condition in order to get a perfect reconstruction [8,9]. since the wavelets are localized functions (which means that they are zero out side a finite interval) with zero mean hence many different base vectors formed by dilation and translation of the mother function. therefore the perfect vector must satisfy the compact support, vanishing dr. walid a. mahmoud/al-khwarizmi engineering journal ,vol.1, no. 2,pp 46-51 (2005) moment, smoothness, and orthogonality [10,11]. for orthogonality property, the condition: ∫ ф (t)ф (t-m) dt =0 …..(1) must hold. where ф (t) is the bases function. m: is the amount of shifting one interval at a time where m not equal 0. for the orthonormality property the condition: ∫ ф (t) dt =1 …..(2) must hold. the orthonormal bases are good in localization for time and frequency and they are related to special filters for the sub band coding. these filters are lead to exact waveform reconstruction without aliasing and without amplitude and phase distortion [10,11]. for the vanishing moments, and smoothing, they are very important especially for the two dimensional applications. since the amount of information is bigger than the one dimensional applications and hence the interference between these information’s is larger so we are in need for high localization in frequency which leeds to made the higher derivations equal to zero. fig. (2) shows the sub bands distribution of the frequency components of the 2-d signal in the wavelet plain. dr. walid a. mahmoud/al-khwarizmi engineering journal ,vol.1, no. 2,pp 46-51 (2005) x(n) h(n) g(n) h(n) g(n) h(n) g(n) x(n) ↓2 ↓2 ↓2 ↓2 coding ĥ(n) ĝ(n) ↑2 ↑2 ┼ ĥ(n) ĝ(n) ↑2 ↑2 ┼ ĥ(n) ĝ(n) ↑2 ↑2 ┼ decoding fig. (2): sub-band coding scheme in terms of mra in the practical situation the filters approach is the appropriate way for analyzing the signal into its frequency components. this way consists of decomposing the signal into high frequency components and low frequency components depending upon the convolution approach [12,13]. in each level the i/p information is separated into approximate information: a (j-1) (n) = ∑fj (k) h (k-2n) …(3) and into detail information: d (j-1) (n) = ∑fj (k) g (k-2n) …(4) where j, j-1 denotes the decomposition level and the level follow it respectively, h(n) and g(n) are the high pass filter (hpf) & low pass filter (lpf) impulse response respectively. where (a) dr. walid a. mahmoud/al-khwarizmi engineering journal ,vol.1, no. 2,pp 46-51 (2005) are the approximated information and the (d) are the detailed information [1]. inverting the above process makes the reconstruction. this is done by: 1) up sampling to over come the down sampling 2) using ĥ(n) & ĝ(n) which are the inverse of h(n) &g(n) respectively so the reconstruction will follow the formula: fj+1=2{∑fj (k) g(n-2k) + ∑fj (k) h(n2k ) …..(5) this is called filter tree decomposition algorithm, where in this algorithm the sub-band coding scheme and since it uses the convolution approach, then the filters will have constant q factor because constant filter taps are used, so the relative frequency bands distribution will be as shown in fig. (3). if we assume using finite impulse response (fir) filters, then it tern out that the hpf & lpf are related by the formula h(l-1-n) = (-1)n g(n) …..(6) where l is the filter length (-1) n is transforming the modulation from lpf into a hpf [13]. according to filter tree decomposition algorithm the classical wavelet transform is obtained by the decomposition (low pass filtering and down sampling). this decomposition is processed only on the low frequency branch since it is the more intelligible part as well as most of the information is in this part. this part of low frequency components with narrow bandwidth has the higher rate of information [4,8]. this part takes calculation in the analyzing part of order o (n) “or its linear in complexity with the decomposition level ’’. ll lh lh hl hh hl hh fig (3): the relative frequency bands distribution dr. walid a. mahmoud/al-khwarizmi engineering journal ,vol.1, no. 2,pp 46-51 (2005) the complete signal analyzing is done by decomposing both the high as well as the low frequency branches. where this will make the mallat decomposition tree to be strictly binary tree (sbt) in which each branch is decomposed into two secondary branches. in this type of decomposition we are facing complexity in the analyzing part of order o (nlog2n) and this is result in completely evenly spaced frequency resolution, and a tree type of a logarithmic splitting and tilling of time – scale plain [6]. the decomposition of the high frequency components which involves wide bandwidth is done by the same strategy (high pass filtering and down sampling) is guarantying the global view of the signal. this is implemented in order to diagnose the positions where the signal has or may has data in it where this kind of analysis is called the complete wavelet transform or wavelet packet transform (wpt)[10,13]. fig (4) shows the signal tree decomposition using the wpt approach while fig (5) shows the frequency distribution of the signal representation in the previous figure. frequency scale fig. (5): the freq. representation of the wpt xll xhh x xl xhl xlh xh fig. (4): the tree representation of the wpt dr. walid a. mahmoud/al-khwarizmi engineering journal ,vol.1, no. 2,pp 46-51 (2005) 3: -fpga: the reason beyond choosing the fpga for the implementation of nearly all the modern digital systems is its fitness for handling the high computationally expensive problems and cover its intensive need for the parallel processing or pipelining [14]. therefore among the advantages of fpgas some are [15,16,17]: 1) the replacement of the small-scale integrated circuits (ssi) and medium-scale integrated circuits (msi) chips. 2) the availability of parts of the shelf. 3) rapid turn around. 4) low risk. 5) some fpgas have the ability of reprogramming. 6) relatively low cost and flexible design. but its relative long design cycle is a disadvantage because its design process generally requires nine steps as follow [15,16,17]: 1) entering the design in the form of schematic, net list, logic expressions, or hdl (hardware descriptive language). 2) simulate the design for functional verification. 3) mapping the design into the fpga architecture. 4) placing and routing the fpga design. 5) extracting the delay parameters of the routed design. 6) re-simulating for time verification. 7) generating the fpga device configuration format. 8) configuring or programming the device. 9) testing the product for undesired functional behavior. this long design cycle force the production companies to face a challengeble problem and hence force them to find suitable solutions. solutions are divided into four categories. the first one is consist of using the schematic approach for designing, which is used if the design elements and the circuit branches are well defined and their functions are specified. the second one is consist of using the very high-speed integrated circuits hardware descriptive languages (vhdl), where this category is used with looping or iterative processes. the third one uses the finite state machine (fsm) which uses with the control circuits, which have small numbers of inputs and outputs. any of the above categories can be merged together to form a new combination for handling new jobs. for example, we can implement a control circuit in an fsm part to control the process flow of a certain function implemented using the schematic approach. the fourth category uses the high dr. walid a. mahmoud/al-khwarizmi engineering journal ,vol.1, no. 2,pp 46-51 (2005) level language which is called the system c4 or system c5 [18]. this branch is a wild force pci plug in board with 5-15 processing elements (pes) with a 1mbyte imbedded memory attached to each pe, and other inter connectors like fifo, crossbars, single inline modules data (simd). this board is installed by its installation software after its placement in the motherboard of the personal computer, where this kind of kits operate on 1,3,5,10,20,33,66 mhz clock frequency with large number of inputs and outputs and wide range of function control and implementation [18]. 4: -fpga simulation of twodimensional wavelet and wavelet packet transform: this paper shows a new proposed circuit design of an fpga digital circuit for the evaluation of the coefficients of the two dimensional wavelet transform; therefore the simulation process should pass through four stages as shown [19,20]. the problem formulation and function establishment represents the first stage. in this stage the general features of the problem are identified in order to specify the needs for the problem solution. in the other hand; the function establishment is very important to specify the necessary equipments and devices for function implementation where the limitations and boundaries are defined. the second stage is represented by over come the limitations and difficulties in a reasonable way keeping an eye to the over all cost. while the implementation of the function must be optimized as much as possible in order to specify the type of the fpga kit, size, capabilities, frequency ranges, number of inputs and outputs, power consumption, scalability, and compatibility. operating the optimized designed kit represents the third stage. generally in this stage two important problems are appearing, the first one is represented by the timing problem, which is the most important. the second one is represented by the production of the undesired results and values through the operating process and the way to get rid of them where most of these values are produced due to the timing problem. the fourth stage is represented by connecting the designed kit to the operating environment and search for its compatibility and the best ways for operating in the presence of other system equipments. therefore it’s preferred to choose the kit type, as near as possible to the type of other system equipment’s in order to reduce the compatibility problems. or if it’s possible and not costly to change the whole system since the fpga kits are dr. walid a. mahmoud/al-khwarizmi engineering journal ,vol.1, no. 2,pp 46-51 (2005) relatively of low cost. for the first stage, the problem is represented by the evaluation of the coefficients of two-dimensional wavelet and wavelet packet transform depending upon filter tree decomposition using the convolution approach. for the second stage, the fpga kit for the implemented design is spartaniie .the spartan-iie 1.8v fpga gives high performance, abundant logic resources, rich features set, all at exceptional low price. this family contains seven members offers density range from 50000 to 600000 system gates with wide operating frequency range (500khz – 2.5ghhz), delivering more i/os and other features per dollar than other fpgas by combining advanced process technology with a streamlined architecture based on the proven vertex-e. features include block ram (288 k bit), distributed ram (221k bit), 19 selectable i/o standard, 4 dll (delay locked loop), fast predictable interconnection means that successive design iteration continue to meet timing requirements. the third stage depending upon the type of application, its operating frequency, its operating speed, and its response time. for example if we are dealing with speech signal then the highest possible frequency component does not accede 6khz in any way. and the speech rate is relatively slow, while in target identification the image verification must be real time and very accurate with a very high response speed for direction changing. but if systems are not in need for high speed and have symmetry in their circuits’ architecture then these symmetric circuits can be combined in few ones. correspondly the operations may be performed in sequence, or else redundant circuits will be built to perform parallel processing or pipe lining to achieve the necessary operating speed. the fourth stage is represented by implementing the whole system from its receiving point to its transmitting point since the used kit is more than enough to handle this task from size, speed, accuracy, cost. so building the whole system on the same kit reduces the compatibility problems to the minimum. in this design we are spotlighting on an important point, which is the usage of multi-purpose instruments to perform multi process. its represented by the full adder/subtractor circuit with the shift register following. this is done to reduce the number of used devices, which reduces the power consumption and hence reduces the heat generation and heat sink size and reduces the kit die area but it will be in need for a control circuit to synchronize the circuit operations. dr. walid a. mahmoud/al-khwarizmi engineering journal ,vol.1, no. 2,pp 46-51 (2005) 5: -demonstrated example: an example will be simulated on a spartan-iie fpga platform using the schematic approach implemented on xilinx foundation 2.1i software. this software provides three types of entrance for the circuit design. either by schematic, or by very high-speed integrated circuit hardware descriptive language (vhdl), or by finite state machine (fsm). this software provides very high programming capabilities that specify the most tiny details in the design (starting from the inputs passing through the latching and interfacing parts reaching to the process and the evaluations right to the outlet of the results to the output circuit). all other necessaries represented by the clock evaluation (1 ghz in the circuit designed), the synchronization problems, design problems (essential hazard, racing, and oscillation problems). the most important part is that the software evaluates the problem and might specify a solution for it. an example of a two-dimension signal of 4*4 matrix will be demonstrated fully with its logical circuit representation and its corresponding results. in this example the full tree decomposition of the two-dimensional wavelet and wavelet packet transform is evaluated. taking in the consideration the arrangement of the input and output data. the data entered vector by vector. the output data obtained as four, 2*2 matrices vector by vector, arranged as hh, hl, lh, ll matrices. each result is represented in sixteen-bit width. between any two cascaded stages there exist latches first to keep the synchronization while translating the data from one stage to another second to hold these values until the circuit reach the stable state in case of value changing due to negative signs, racing, essential hazard, or oscillation occurs. each stage operate asynchronously in order to speed up the process (combinational logic circuits) with no delay or storing devices. but the delivery from one stage to the next one must be done under full circuit control synchronization. the input matrix is: the output matrices are: 1 1 0 1 2 1 1 0 0 2 1 1 3 0 1 2 4*4 2 5 5 2*2 hh= -1 0 -1 -1 2*2 hl= 1 0 1 -1 2*2 lh= -1 -2 -5 1 2*2 ll= dr. walid a. mahmoud/al-khwarizmi engineering journal ,vol.1, no. 2,pp 46-51 (2005) fig (6): the decomposition circuit of 2d wavelet packet transform 16 bit full adder/ subtractor 16 bit full adder/ subtractor 16 bit full adder/ subtractor 16 bit full adder/ subtractor 16 bit full adder/ subtractor 16 bit full adder/ subtractor 16 bit full adder/ subtractor 16 bit full adder/ subtractor 5 bit synchronous counter 12h hh r11 hh r12 hl r11 hl r12 lh r11 lh r12 ll r11 ll r12 hh r21 hh r22 hl r21 hl r22 lh r21 ll r21 ll r22 lh r22 16 bit full adder/ subtractor 16 bit full adder/ subtractor 16 bit full adder/ subtractor 16 bit full adder/ subtractor 16 bit full adder/ subtractor 16 bit full adder/ subtractor 16 bit full adder/ subtractor 16 bit full adder/ subtractor th e in pu t d at a fr om th e ex te rn al e nv iro nm en ts fr om th e to p “e le m en t 1 ,1 ” to th e bo tto m “ el em en t 4 ,4 ” ro w b y ro w 15h controller =1 dr. walid a. mahmoud/al-khwarizmi engineering journal ,vol.1, no. 2,pp 46-51 (2005) fig (7): the reconstruction circuit of 2d wavelet packet transform 16 bit full adder/ subtracto 16 bit full adder/ subtracto 16 bit full adder/ subtracto 16 bit full adder/ subtracto 16 bit full adder/ subtracto 16 bit full adder/ subtracto 16 bit full adder/ subtracto 16 bit full adder/ subtracto hh r11 hh r12 hl r11 hl r12 lh r11 lh r12 ll r11 ll r12 hh r21 hh r22 hl r21 hl r22 lh r21 ll r21 ll r22 lh r22 5 bit synchronous counter 12h 16 bit full adder/ subtracto 16 bit full adder/ subtracto 16 bit full adder/ subtracto 16 bit full adder/ subtracto 16 bit full adder/ subtracto 16 bit full adder/ subtracto 16 bit full adder/ subtracto 16 bit full adder/ subtracto th e ou tp ut d at a fro m th e re co ns tru ct io n ci rc ui t w hi ch re pr es en ts th e in pu t d at a in pu t t o th e d ec om po si tio n ci rc ui t f ro m th e to p “e le m en t 1 ,1 ” to th e bo tto m “ el em en t 4 ,4 ” 15h controller =1 dr. walid a. mahmoud/al-khwarizmi engineering journal ,vol.1, no. 2,pp 46-51 (2005) tables (1) and (2) shows the decomposition and reconstruction result evaluation respectively for the 4*4 signal given above. table (1): -the design result evaluation of the two dimensional 4*4 point’s decomposition circuit data input first stage second stage data output 0000000000000001 (1) 0000000000000011 (3) 0000000000000110 (6) 0000000000000110 0000000000000010 (2) 1000000000000001 (-1) 0000000000000100 (4) 0000000000000100 0000000000000000 (0) 0000000000000011 (3) 0000000000000101 (5) 0000000000000101 0000000000000001 (1) 0000000000000001 (1) 0000000000000101 (5) 0000000000000101 0000000000000010 (2) 0000000000000000 (0) 0000000000000000 (0) 0000000000000000 0000000000000001 (1) 0000000000000000 (0) 1000000000000100 (-4) 1000000000000100 1111111111111011 0000000000000000 (0) 0000000000000100 (4) 1000000000000011 (-3) 1000000000000011 1111111111111100 0000000000000011 (3) 1000000000000010 (-2) 1000000000000011 (-3) 1000000000000011 1111111111111100 0000000000000000 (0) 0000000000000001 (1) 0000000000000000 (0) 0000000000000000 0000000000000011 (3) 1000000000000001 (-1) 1000000000000010 (-2) 1000000000000010 1111111111111101 0000000000000001 (1) 0000000000000100 (4) 0000000000000001 (1) 0000000000000001 0000000000000010 (2) 0000000000000010 (2) 0000000000000001 (1) 0000000000000001 0000000000000001 (1) 0000000000000001 (1) 1000000000000010 (-2) 1000000000000010 1111111111111101 0000000000000001 (1) 0000000000000001 (1) 0000000000000010 (2) 0000000000000010 0000000000000000 (0) 0000000000000100 (4) 1000000000000011 (-3) 1000000000000011 1111111111111100 0000000000000010 (2) 0000000000000000 (0) 0000000000000001 (1) 0000000000000001 dr. walid a. mahmoud/al-khwarizmi engineering journal ,vol.1, no. 2,pp 46-51 (2005) table (2): -the design result evaluation of the two dimensional 4*4 point’s reconstruction circuit data input first stage second stage data output 0000000000000110 0000000000000110 (6) 0000000000000100 (4) 0000000000000001 (1) 0000000000000100 0000000000000110 (6) 0000000000001000 (8) 0000000000000010 (2) 0000000000000101 0000000000000000 (0) 0000000000000000 (0) 0000000000000000 (0) 0000000000000101 0000000000001000 (8) 0000000000000100 (4) 0000000000000001 (1) 0000000000000000 0000000000000010 (2) 0000000000001000 (8) 0000000000000010 (2) 1000000000000100 1111111111111011 0000000000001000 (8) 0000000000000100 (4) 0000000000000001 (1) 1000000000000011 1111111111111100 0000000000000010 (2) 0000000000000000 (0) 0000000000000000 (0) 1000000000000011 1111111111111100 0000000000001000 (8) 0000000000001100 (12) 0000000000000011 (3) 0000000000000000 1000000000000010 (-2) 0000000000000000 (0) 0000000000000000 (0) 1000000000000010 1111111111111101 0000000000000010 (2) 0000000000001100 (12) 0000000000000011 (3) 0000000000000001 0000000000000000 (0) 0000000000000100 (4) 0000000000000001 (1) 0000000000000001 1000000000000100 (-4) 0000000000001000 (8) 0000000000000010 (2) 1000000000000010 1111111111111101 1000000000000010 (-2) 0000000000000100 (4) 0000000000000001 (1) 0000000000000010 0000000000000100 (4) 0000000000000100 (4) 0000000000000001 (1) 1000000000000011 1111111111111100 0000000000000010 (2) 0000000000000000 (0) 0000000000000000 (0) 0000000000000001 0000000000000000 (0) 0000000000001000 (8) 0000000000000010 (2) the output results here suffering from a problem that they are multiplied by certain factor which is 4 because we are decomposing for two levels only in the high and the low frequency branches. so we must divide her the data by 4 or the data must be shifted for 2 bits. dr. walid a. mahmoud/al-khwarizmi engineering journal ,vol.1, no. 2,pp 46-51 (2005) 6: -conclusions: the aim of this paper is to propose a new circuit design for the implementation and evaluation of the two-dimensional wavelet and wavelet packet transform. in this design the dsp point of view was adapted, where nearly in all other designs the implemented circuits where from the communication point of view, where this type of designs need no wide range filter taps design which reduces the cost. because of the kit wide capabilities high speed, high accuracy, low cost, low power consumption, and easy to be handled where achieved. other privilege is achieved by overcoming the disadvantage of the conventional wavelet and wavelet packet transform coder-decoder which is not able to produce the coefficients until the signal is complete. the production now is achieved while the data is received with no need to wait. for example; if the signal is of 8*8 then the evaluation of the wt & wpt coefficients will start if the received signal is of 4*4 to fit for the designed circuit. 7: -references: [1] jan e. odegard & ivan w. selensnick 1993 “introduction to wavelet and wavelet transform”. [2] f.argentini, g.benelli, reprinted from electronic letters, vol 28, pp 513-515, 27th february 1992 “iir implementation of wavelet decomposition for digital filter analysis “. [3] a.aron & e.rosenberg, ieee transactions, vol. 64, pp 475-487, april 1986. “speaker verification using pattern recognition approach “. [4] n. rex dixon & thomas b. martin 1989.a volume in the ieee press selected reprint series “automatic speech and speaker recognition “. [5] l.r.rabiner & r.w. shafer 1982 “digital processing of speech signal”. [6] lawrence rabiner & biing – hwang juang 1993 “fundamentals of speech signals”. [7] c.cheng, msc thesis, rise university, department of electrical engineering, may 1996. “wavelet signal processing of digital audio with application in electro-acoustic music “. [8] g.r.doddington processing of electr.76, pp 22-26, may 1976. “personal identity verification using voice “. [9] r.j.mammare, x.zhang, & ramachadram, ieee signal processing magazine, pp 58-71, september 1996 “robust speaker recognition “. [10] d.e.newland, third addition, 1994. “an introduction to random vibration spectral and wavelet transform “. [11] a.chinienti, i. cibrario, r. picco, dsp 1997 vol56 p.p 633-636 ”filter evaluation of dr. walid a. mahmoud/al-khwarizmi engineering journal ,vol.1, no. 2,pp 46-51 (2005) wavelet transform”. [12] dusan levicky, emil matus, peter kral, electrical engineering 1996 vol.47 p.p281-286 ”wavelet transform analysis-synthesisalgorithms”. [13] mohammad n.hussain, msc. thesis, university of baghdad, department of electrical engineering, october 2000, “speaker recognition based upon phonemes using wavelet packet transform”. [14] v.herrero, j.cerda, r.gadea, m.martinez, a.sebestia, group of design of digital systems, department of electrical engineering, june 2003, “implementation of 1-d daubechies wavelet transform on fpga”. [15] piyush jamkhandi, amar mukherjee, kunal mukherjee, robert franceschini, school of electrical engineering and computer science, july 2003, “ parallel h/ws/w architecture for computation of discrete wavelet transform using rmf algorithm”. [16] sarin george mathen, thesis, university of kansas ,june 2000, “wavelet transform based adaptive image compression on fpga”. [17] www.xilinix.com, july 2003, “spartan-iie 1.8 v fpga family: introduction and ordering information’s”. [18] pak k. chan, university of california, october 2000, “digital design using field programmable gate array”. [19] john e. gilbert , september 2003, “wavelets : theory and applications on fpga”. [20] miguel figueroa , chris diorio, university of washington ,september 2003,”a 200 mhz , 3mw,16-tap mixed –signal fir filter”. http://www.xilinix.com <4d6963726f736f667420576f7264202d203133332d20313432e6d3e420d3e5ede120e6d2edc7cfe6e3cde3cf> al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 14, no. 4, december, (2018) p.p. 133142 mechanical properties of burnished steel aisi 1008 zeyad d. kadhim* mohammed abdulraoof abdulrazzaq** wassan suheil hussain*** *, ***department of materials engineering/ college of engineering/ al-mustansiriyah university /baghdad/ iraq **department of mechanical engineerin/ college of engineering /al-mustansiriyah university /baghdad, iraq *email: dr.zeyad@yahoo.com **email: mohammedraof415@yahoo..com ***email: wassansona93@gmail.com (received 24 december 2017; accepted 3 june 2018) https://doi.org/10.22153/kej.2018.06.005 abstract burnishing improves fatigue strength, surface hardness and decrease surface roughness of metal because this process transforms tensile residual stresses into compressive residual stresses. roller burnishing tool is used in the present work on low carbon steel (aisi 1008) specimens. in this work, different experiments were used to study the influence of feed parameter and speed parameter in burnishing process on fatigue strength, surface roughness and surface hardness of low carbon steel (aisi 1008) specimens. the first parameter used is feed values which were (0.6, 0.8, and 1) mm at constant speed (370) rpm, while the second parameter used is speed at values (540, 800 and 1200) rpm and at constant feed (1) mm. the results of the fatigue test showed that improvement in fatigue limit, where the highest fatigue limit was obtained at (1mm feed, 1200rpm speed) in burnishing process which was (169 mpa). the hardness results, showed increasing feed and speed values lead to increasing the hardness. the burnishing process reduces surface roughness by producing accurate and better surface finish. the best surface fineness of metal at (1mm feed and 1200 rpm speed) was 0.11 μm. keywords: burnishing process, fatigue properties, low carbon steel (aisi 1008), surface hardness of low carbon steel, surface roughness of low carbon steel. 1. introduction fatigue strength is one of most common mechanical properties. durability and reliability of car part is usually defined by its fatigue resistance, so most of them can be loaded by dynamic load. failure of fatigue often begins from surface of the metal. that is related with the fact that most severe fatigue plastic deformations occur in one grain thickness layer of the metal surface [1]. most of the surface treatments produces compressive stresses at the metal surface, which reduce the probability of crack initiation and then its expansion at the interface between (the surface and core), thus increasing the metal resistance to fatigue [2]. most important impacts of roller burnishing improve the fatigue strength, the surface hardness and surface roughness. this process can be transform tensile residual stresses, present in the surface zone after turning, to compressive residual stress [3]. burnishing process is a cold working process in which plastic deformation happens by applying the pressure within a roller or ball on metal surface. this process is also strengthening and finishing process [4]. burnishing process is low cost metal surface treatment and applied to improve quality of the surfaces [5]. d. mahajan and r. tajane (2013) [6] showed that a burnished surface has a high surface hardness and better fatigue life. results explained that aluminum and steel materials are chosen by the authors. results showed that roller burnishing process parameters zeyad d. kadhim al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 133142 (2018) 134 such as burnishing force, speed and feed improve fatigue strength and produce better surface finish. m. rao et al (2011) [7] showed that different experiments are conducted for explaining influence of burnishing forces and number of the tool passes on metal surface hardness and metal surface roughness of mild steel samples. results showed that improvement in the surface roughness and surface hardness were achieved by application of roller burnishing process with mild steels specimen. sh. dwivedi et al. (2014) [8] studied the mechanical properties (hardness, tensile strength and ductility) of a356/5%sic metal matrix composites for unburnished samples and burnished samples. the results showed that the roller burnished samples of a356/ 5% sic led to improve surface hardness and ductility. s. thamizhmanii and s. hassan (2009) [9] studied that burnishing process carried out for improving surface hardness, surface roughness, fatigue strength and compressive residual stresses, this is accomplished by using sliding feed rates, speeds and penetration depths. this process smooth out peak and valley on the metal surface and accomplished by multiroller burnishing fitted in housing and freely rotates in a horizontal axis. korzynski m. et al (2011) [10] studied effect of burnishing parameters on the surface roughness and obtained from the mathematicals model, and multi nominals of second order that allows for the interactions of input factors for the burnished 42crmo4 alloy steels shafts. from analysis of results it was concluded that the surfaces micro hardness increased by up for 29%. franzen v. et al (2010) [11] showed that parameters of the roller burnishing process had high effect on surface topology of friction elements and their tribological properties. s. thamizhmnaii (2008) [12] studied investigation of surface hardness and surface roughness on titanium alloys by using roller burnishing tool that were accomplished by many authors and the results were presented. f. gharbi et al (2011) [13] investigated that the surface hardness for aisi 1010 steel increases with increasing number of passes for burnishing tool and burnishing force. f. shiou et al (2003) [14] used taguchi l18 orthogonal array techniques and anova to study surface roughness value. it was found that vickers hardness improved from 338 to 480 after ball burnishing and the surface roughness improving of injection parts on plane surface was 62.9% and that on the free form surface was 77.8%. u. shirsat et al (2004) [15] worked on the parametric analysis of ball burnishing and combined turning. results explained that the micro hardness increased with force up for certain extent. m. el-axir (2000) [16] studied mathematical models that presented to predict surface roughness and micro hardness of st-37 caused by roller burnishing process under lubricated condition. it was shown that a spindle speed, burnishing feed, burnishing force and number of passes have significant influence on surface micro hardness and surface roughness. 2. aim of the research the main objective of this research is to find the fatigue limit of untreated and burnished low carbon steel aisi 1008 by using surface forming process named burnishing process, also examine the mechanical properties of low carbon steel aisi 1008 such as hardness and surface roughness. 3. experimental work 3.1 materials the material studied in this current work was low carbon steel alloy type of aisi 1008 which is used in various steel components, such as gears, shafts and cams (according to j. dossett and g.e. totten [17]). 3.2 chemical analysis chemical analysis of the tested material (aisi 1008 low carbon steel) was accomplished by (thermo arl 3460, optical emission spectrometer) in state company for inspection and engineering rehabilitation in baghdad. the results are compared with american standard carbon steels test method. zeyad d. kadhim al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 133142 (2018) 135 table 1, chemical composition for low carbon steel aisi 1008 in wt %. 3.3 stress relieve of the specimens this treatment was carried out by placing the samples in crucible and then put it in the oven at temperature 220 ºc for three hours to relieve stresses. this treatment carried out in materials engineering department/ college of engineering/ al-mustansiriayah university. 3.4 burnishing process the samples used in this work treated with special burnishing tool that worked with a lathe to accomplish this process. there are two variables used in this process, feed and speed. this process carried out on sixty samples of fatigue specimens, first group of this samples consist of thirty samples in which speed parameter is constant and feed parameter is variable (feed values used were 0.6, 0.8, 1mm at 370 rpm constant speed), second group also consist of thirty samples in which feed parameter is constant and speed parameter is variable (speed values used were 540, 800, 1200 rpm at 1mm constant feed). burnishing process carried out in the mechanical workshop/ college of engineering/al-mustansiriayah university as shown in figures (1, 2). fig. 1. roller burnishing tool. fig. 2. burnishing process. 3.5 fatigue test fatigue test was accomplished by using fatigue test machine of type (hsm20 rotating bending fatigue machine, germany). the fatigue test specimens prepared according to the (din50113) standard specification as shown in figure (3). to get suitable dimensions of the fatigue specimens according to the standard dimensions of (hsm20 rotating bending fatigue machine), for this, all specimens were manufactured by using conventional lathe machine (harrison 600, m350, ew700, germany). to produce good surface finish and to minimize the residual stresses, all specimens manufactured with a careful control. the specimen is subjected to an applied load from the right side which was perpendicular to the axis of specimens, developing bending moment. therefore; surface of the specimen is under tension and compression stresses when it rotates. (1) σ (n/mm²)= (32 × 125 p)/(π × d³) (according to hashemi, s. [18]) where σ = stress (n/mm²), p = force in n, the force arm is equal to 125mm and, d = minimum diameter of the specimen in (mm). constant fatigue tests were conducted in laboratory air (approximately 25-30% relative humidity) at temperature of room using hsm20 rotary fatigue bending machine, germany, as shown in figure (4), with a stress ratio of r= -1. the cycle frequency was 50 hz and the rotating speed used is (3000 cycle/min.). this test was chemical composition material fe cu al ni mo cr s p mn si c aisi 1008 0.05 0.040 (max) 0.3 0.5 0.10 (max) standard value bal. 0.222 0.016 0.085 0.002 0.056 0.016 0.005 0.487 0.150 0.073 actual value zeyad d. kadhim al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 133142 (2018) 136 carried out in mechanical engineering department/ almustansiriayah university/ baghdad/ iraq. fig. 3. fatigue test specimen (dimensions in mm). fig. 4 fatigue testing machine hsm20, (germany) rotating . 3.6 the surface roughness measurement surface roughness was measured for the samples which used whose used for fatigue test, and it has found that value of the surface roughness is ranging from (0.156 2.181) micron. ten samples subjected to surface roughness measurement, where they were measured by using the surface roughness measuring device (tr200). 3.7 microhardness test vickers microhardness test was done on ten samples with a load of 3 n with a load holding time of 10 seconds. indentations were made starting 0.25 mm from the edge end at an interval of 0.25mm to a distance of 3mm towards the middle and repeated when specimens turned at right angles from the first measurement. 4. results and discussion 4.1 fatigue test results figures [5 7] showed the fatigue curves for each condition, it can be seen that the highest value for fatigue limit was (169.102 mpa) for samples that treated with (1mm feed, 1200rpm speed) burnishing process, this is due to the creation high residual compressive stresses at the surface of specimens and also reduce the crack initiation and increase dislocations density during this process (according to zabkar, b. and kopač, j. [16]). table (2) shows an improvement in fatigue limit for sample treated with burnishing process. table 2, fatigue of low carbon steel (aisi 1008) results. cases treatment fatigue limit (mpa) no. of cycle a without treatment 79.6 2×106 b burnishing (speed 370 rpm, feed 0.6mm) 91.5 5×106 c burnishing (speed 370 rpm, feed 0.8mm) 101.5 6×106 d burnishing (speed 370 rpm, feed 1mm) 119.5 7×106 e burnishing (speed 540 rpm, feed 1mm) 139.2 8×106 f burnishing (speed 800 rpm, feed 1mm) 159 1×107 g burnishing (speed 1200 rpm, feed 1mm) 169 1×107 4.1.1 fatigue test results of as received low carbon steel (aisi 1008) ten samples were tested at room temperature. the applied stresses were in a range of (79.6-169 mpa). the fatigue limit of untreated low carbon steel (aisi 1008) was at 79.6 mpa. zeyad d. kadhim al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 133142 (2018) 137 fig. 5. (s-n curve for untreated low carbon steel aisi 1008) this group (untreated low carbon steel aisi 1008) subjected to fatigue test in different stresses to extract value of fatigue limit which was 79.6 mpa as shown in figure (5). 4.1.2 fatigue test results of (0.6mm feed and 370 rpm speed) ten samples were tested at room temperature. the applied stresses were in a range of (91.5-189 mpa). the fatigue limit of (0.6mm feed and370rpm) burnished low carbon steel (aisi 1008) was at 91.5 mpa. this value is higher than untreated one, this result due to produce good surface finish, work hardening and compressive residual stresses by plastically deforming the metal surface layer in burnishing process. 4.1.3 fatigue test results of (0.8mm feed and 370rpm speed) ten samples were tested at room temperature. the applied stresses were in a range of (101.5-209 mpa). the fatigue limit of (0.8 mm feed and 370 rpm speed) burnished low carbon steel (aisi 1008) was at 101.5 mpa. this group treated with (0.8 mm feed and 370 rpm speed value) burnishing process and subjected to fatigue test at room temperature and the result was that fatigue limit of this group is 101.5 mpa as shown in figure (6), this increasing in fatigue limit due to produce compressive residual stresses and work hardening by plastically deforming the specimens surface layer in burnishing process. 4.1.4 fatigue test results of (1mm feed and 370 rpm speed) ten samples were tested at room temperature. the applied stresses were in a range of (119.5-219 mpa). the fatigue limit of (1mm feed and 370rpm) burnished low carbon steel (aisi 1008) was at 119.5 mpa. this group treated with (1 mm feed and 370 rpm speed value) burnishing process and subjected to fatigue test at room temperature and the result was that fatigue limit of this group is 119.5 mpa as shown in figure (6), this increasing in fatigue limit due to produce work hardening and compressive residual stresses by plastically deforming the metal surface layer in burnishing process. figure (6) below shows a comparison among s-n curves of untreated samples and (0.6, 0.8 and 1) mm feed values of burnishing process. in this figure it can be seen that fatigue limit improved whenever feed values increased, where untreated samples have fatigue limit (79.6 mpa) while (1mm feed value and 370 rpm speed value) burnished metal have fatigue limit (119.5 mpa). fig. 6. (s-n for low carbon steel aisi 1008 with burnishing process at different feed and constant speed 370 rpm) 4.1.5 fatigue test results of (1mm feed and 540rpm speed) ten samples were tested at room temperature. the applied stresses were in a range of (139.2-238.7 mpa). the fatigue limit of (1mm and 540rpm) burnished low carbon steel (aisi 1008) was at 139.2 mpa. this group treated with (1 mm feed and 540 rpm speed value) burnishing zeyad d. kadhim al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 133142 (2018) 138 process and subjected to fatigue test at room temperature and the result was that fatigue limit of this group is 139.2 mpa as shown in figure (7), this value higher than untreated one, this is due to work hardening which produce compressive residual stresses at the specimen surface in burnishing process. 4.1.6 fatigue test results of (1mm feed and 800rpm speed) ten samples were tested at room temperature. the applied stresses were in a range of (159-248.5 mpa). the fatigue limit of (1mm and 800rpm) burnished low carbon steel (aisi 1008) was at 159 mpa. this group treated with (1 mm feed and 800 rpm speed value) burnishing process and subjected to fatigue test at room temperature and the result was that fatigue limit of this group is 159 mpa as shown in figure (7), this is due to cold working process which produces compressive residual stresses at the specimen surface in burnishing process. 4.1.7 fatigue test results of (1mm feed and 1200rpm speed) ten samples were tested at room temperature. the applied stresses were in a range of (169-258.5 mpa). the fatigue limit of (1mm and 1200rpm) burnished low carbon steel (aisi 1008) was at 169 mpa. this group treated with (1 mm feed and 1200 rpm speed value) burnishing process and subjected to fatigue test and the result was that fatigue limit of this group is 169 mpa as shown in figure (7), this is the highest fatigue limit due to cold working process which produce compressive residual stresses by plastic deformation of the specimens surface in the burnishing process. figure (7) below shows a comparison among s-n curves of untreated samples and (540, 800 and 1200) rpm speed values of burnishing process. in this figure it can be seen that fatigue limit improved whenever speed values increased, where untreated samples have fatigue limit (79.6 mpa) while (1mm feed value and 1200 rpm speed value) burnished metal have fatigue limit (169 mpa). fig. 7. (s-n for low carbon steel aisi 1008 with burnishing process at different speed and constant feed 1 mm) 4.2 microhardness test the surface hardness of the samples has been measured by using vickers hardness test. in general the surface hardness increased with burnishing process. values of the surface hardness for the samples were treated with burnishing have higher values than those of untreated, as shown in the table (3). table 3, vickers microhardness of low carbon steel aisi 1008. cases treatment hardness values for vickers(hvn) a without treatment 170 b burnishing (speed 370rpm, feed 0.6mm) 206 c burnishing (speed 370rpm, feed 0.8mm) 207 d burnishing (speed 370rpm, feed 1mm) 212 e burnishing (speed 540rpm, feed 1mm) 199 f burnishing (speed 800rpm, feed 1mm) 210 g burnishing (speed 1200rpm, feed 1mm) 220 4.3 discussion of the microhardness results in figures [(8) and (9)] it can be seen the change in the hardness values. figure (8) showed how hardness values increased with increase of feed values for used specimens and figure (9) also showed how hardness increased with increase of zeyad d. kadhim al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 133142 (2018) 139 speed values for used specimens in burnishing process. from table (3) it can be seen that the surface hardness improved by using burnishing process, from this we can conclude that high value of plastic deformation occurred on the metal surface (according to zabkar, b. and kopač, j. [16]). fig. 8. effect of feed of burnishing process on hardness at constant speed (370 rpm). figure (8) showed how the hardness values increased with increase of feed values in burnishing process for used specimens; this is due to work-hardened surface by plastic deformation, which created form burnishing process. the highest value of the surface hardness obtained when the feed value was (1) mm, at constant speed value which was (370) rpm, which was (212.2) hvn. fig. 9. effect of speed of burnishing process on hardness at constant feed (1mm). figure (9) showed how the hardness values increased with increase of speed values in burnishing process for used specimens. this is because of work hardening during this process, which leads to improve surface quality. the highest value of the surface hardness obtained when the speed value was (1200) rpm, at constant feed value which was (1) mm, which was (220.13) hvn. 4.4 surface roughness test the surface roughness of samples have been measured, and it has been found that surface roughness values decreased for samples that treated with burnishing process. surface roughness of the samples which treated with burnishing process has lower values than those which untreated, as shown in the table (4). 4.5 discussion the results of the surface roughness table 4, surface roughness values for samples of low carbon steel aisi 1008 cases treatment surface roughness (μm) a with out treatment 0.237 e burnishing (speed 370rpm, feed 0.6mm) 0.221 f burnishing (speed 370rpm, feed 0.8mm) 0.215 g burnishing (speed 370rpm, feed 1mm) 0.207 h burnishing (speed 540rpm, feed 1mm) 0.173 i burnishing (speed 800rpm, feed 1mm) 0.156 j burnishing (speed 1200rpm, feed 1mm) 0.110 from table 4 it can be found that surface roughness values for all samples at different conditions. from figures [(10) and (11)] it can be remarked that surface roughness decreased for samples that treated with burnishing process. the lowest surface roughness obtained when the metal treated with (1 mm feed value and 1200 rpm speed value) burnishing process that its value is (0.110 μm). this result obtained because in burnishing process the material near a machined surface is displaced from peaks to fill valleys of the surface profile (according to zabkar, b. and kopač, j. [16]). zeyad d. kadhim al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 133142 (2018) 140 fig. 10. influence feed values of burnishing process on surface roughness of the samples. figure (10) explained that the surface roughness decreased with increase of feed values in burnishing process for used specimens. the lowest value of the surface roughness obtained when feed value was (1) mm, at constant speed value which was (370) rpm, which was (0.207) μm this is due to the material near a machined surface is displaced from peaks to fill valleys of surface profile during this burnishing process (according to malleswara rao j. n. et al [7]). fig. 11. influence speed values of burnishing process on surface roughness of the samples. figure (11) showed that the surface roughness decreased with increase of speed values in burnishing process for used specimens. the lowest value of the surface roughness obtained when the speed value was (1200) rpm, at constant feed value which was (1) mm, which was (0.110) μm this is due to the material near a machined surface is displaced from peaks to fill valleys of the surface profile during this burnishing process causing better surface fineness (according to malleswara rao j. n. et al [7]). 5. conclusions the improvement of the mechanical properties of low carbon steel aisa 1008 by using burnishing process yielded the following conclusions: 1. increasing feed value of burnishing process led to improve fatigue limit. the highest value of fatigue limit (119.5 mpa) was obtained at (1mm) feed and (370rpm) constant speed of burnishing process. 2. increasing speed value of burnishing process led to improve fatigue limit. the highest value of fatigue limit(169 mpa) was obtained from (1200 rpm) speed and (1 mm) constant feed of burnishing process which was 3. increasing feed value of burnishing process led to increase hardness value. the highest value of hardness (212.2 hvn) was obtained from (1mm) feed and (370rpm) constant speed of burnishing process. 4. increasing speed value of burnishing process led to increase hardness value. the highest value of hardness (220.13 hvn) was obtained from (1200 rpm) speed and (1 mm) constant feed of burnishing process. 5. increasing feed value of burnishing process led to decrease surface roughness value. the lowest value of surface roughness (0.207 μm) was obtained from (1mm) feed and (370rpm) constant speed of burnishing process. 6. increasing speed value of burnishing process led to decrease surface roughness value. the lowest value of surface roughness (0.110 μm) was obtained from (1200 rpm) speed and (1 mm) constant feed of burnishing process. 6. references [1] terentjev, v.f. 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[12] thamizhmnaii s., bin omar b., saparudin, s. and hassan s., "surface roughness investigation and hardness by burnishing on titanium alloy", journal of achievements in materials and manufacturing engineering, 2008. [13] f.gharbi, s. sghaier, k. j. al fadhalah, and t. benameur, "effect of ball burnishing process on the surface quality and microstructure properties of aisi 1010 steel plates", journal mater process technology, volume 20, 2011. [14] fang jung shiou, chien hua chen, "freeform surface finish of plastic injection mold by using ball burnishing process", national taiwan university of science and technology, taipei, taiwan, 2003. [15] u. m. shirsat, b. b. ahuja, "parametric analysis of combined turning and ball burnishing process", international journal of engineering and material science, volume 11, 2004. [16] el-axir mh "an investigation into roller burnishing", international journal machine tools manufacturing, 2000. [17] j. dossett and g.e. totten, "asm handbook", volume 4a, steel heat treating fundamentals and processes, asm, 2013. [18] hashemi, s., "foundations of materials science and engineering", 4th edition, 2006. )2018( 133142، صفحة 4، العدد14دجلة الخوارزمي الهندسية المجلم زياد دوشان كاظم 142 aisi 1008 الخواص الميكانيكية للصلب المصقول نوع وسن سهيل حسين*** محمد عبد الرؤوف عبد الرزاق** زياد دوشان كاظم* بغداد/ العراق /الجامعة المستنصرية / قسم هندسة المواد،*** * / بغداد/ العراق /الجامعة المستنصرية هندسة الميكانيكية القسم ** dr.zeyad@yahoo.com :البريد االلكتروني* mohammedraof415@yahoo..com :البريدااللكتروني** wassansona93@gmail.com :البريد االلكتروني*** الخالصة دات الضغطية الصقل يحسن مقاومة الكالل، الصالدة السطحية ويقلل الخشونة السطحية للمعدن ألنه هذه العملية تحول اجهادات الشد المتبقية الى االجها تجارب مختلفة في هذا العمل، (aisi 1008). المتبقية. أداة الصقل األسطواني أستخدمت في العمل الحالي على عينات الفوالذ منخفض الكاربون نوع الخشونة السطحية والصالدة السطحية لعينات الفوالذ منخفض أنجزت لدراسة تأثير عامل التغذية وعامل السرعة في عملية الصقل على مقاومة الكالل، دورة/ دقيقة، بينما ثاني عامل ) ٣٧٠مليميتر في سرعة ثابتة ( )١، ٠٫٨، ٠٫٦أول عامل مستخدم هو قيم التغذية التي كانت ( (aisi 1008). الكاربون نوع تحسين حد الكالل، ه تم) مليميتر. نتائج اختبار الكالل توضح بأن١) دورة/دقيقة في تغذية ثابتة (١٢٠٠، ٨٠٠، ٥٤٠مستخدم هو قيم السرعة التي كانت ( دورة/ دقيقة قيمة السرعة) في عملية ١٢٠٠مليميتر قيمة التغذية ، ١حيث أعلى قيمة لحد الكالل تم الحصول عليها من العينات التي تمت معاملتها مع ( الى زيادة الصالدة لسطح المعدن. نتائج اختبار ) ميكا باسكال. من نتائج اختبار الصالدة نالحظ ان زيادة قيم التغذية والسرعة يؤدي ١٦٩الصقل والتي كانت ( عومة الخشونة السطحية، في هذا البحث، توضح ان عملية الصقل تقلل الخشونة السطحية بأنتاج انهاء سطحي دقيق وجيد على سطح المعدن حيث أفضل ن .) مايكرومتر٠٫١١٠) من عملية الصقل والتي هي (دورة/ دقيقة قيمة السرعة ١٢٠٠مليميتر قيمة التغذية ، ١للمعدن يمكن الحصول عليها من ( \(microsoft word \\316\\341\\346\\317 \\346\\307\\315\\343\\317\) al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 4653 (2013) design of an adaptive pid neural controller for continuous stirred tank reactor based on particle swarm optimization khulood a. dagher* ahmed s. al-araji** * department of computer science / college of science / university of baghdad ** department of control and systems engineering / university of technology *email:dagherkhulood@yahoo.com *email:ahmedsas2040@yahoo.com (received 16 may 2013; accepted 11 november 2013) abstract a particle swarm optimization algorithm and neural network like self-tuning pid controller for cstr system is presented. the scheme of the discrete-time pid control structure is based on neural network and tuned the parameters of the pid controller by using a particle swarm optimization pso technique as a simple and fast training algorithm. the proposed method has advantage that it is not necessary to use a combined structure of identification and decision because it used pso. simulation results show the effectiveness of the proposed adaptive pid neural control algorithm in terms of minimum tracking error and smoothness control signal obtained for non-linear dynamical cstr system. keywords: particle swarm optimization, pid controller, neural network, cstr. 1. introduction in recent years, the adaptive control techniques in the industry process have made great advances. numerous control methods such as adaptive neural control and adaptive fuzzy control have been studied. among them, the best known is the adaptive proportional-integral-derivative (pid) controller, which has been widely used in the industry because of its simple structure and robust performance in a wide range of operating conditions [1]. there are many classic tuning methods for pid parameters such as trial and error method or ziegler-nichol’s method. unfortunately, it has been quite difficult to tune properly the gains of pid controllers because many industrial plants are often burdened with problems such as high order, time delays, and nonlinearities. it is hard to determine optimal or near optimal pid parameters with the classic tuning method. for these reasons, it is highly desirable to increase the capabilities of pid controllers by adding new features. many artificial intelligence (ai) techniques have been employed to improve the controller performances for a wide range of plants while retaining their basic characteristics [2]. in addition to that, there are many control methodologies for continuous stirred tank reactor (cstr) system that it's strong nonlinear behavior such as follows. a pid self adaptive control method based on on-line optimization of pid controller parameters by the differential evolution algorithm is stated in [3]. a practical non-linear pid controller that utilizes a local model (lm) network, which combines a set of local models within an artificial neural network (ann) structure, to adaptively characterize the cstr process nonlinearity is explained in [2]. the control of cstr using state feedback gain using pole placement technique is investigated in [4]. the state feedback gain parameters are gain scheduled using fuzzy logic control to provide the appropriate values for the different regions. in [5] it is used two strategies for adaptive control of a nonlinear cstr process, adaptive general predict control and model reference khulood a. dagher al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 4653(2013) 47 adaptive control the polynomial approach connected with pole-placement method. the artificial neuro-fuzzy inference system (anfis) gain scheduled genetic algorithm (ga) based pid is proposed for cstr as in [6]. also in [7] is proposed a predictive control strategy for nonlinear dynamics of a cstr process based on a neuro-fuzzy network and l infinite. hybrid adaptive inverse control based on neural fuzzy system is presented and explained in [8]. it consists of two control loops, inverse control and pid control. pid control is a complement for inverse control and is mainly used to eliminate static error existing in direct inverse control when the inverse model is uncertain. a nonlinear model predictive control (nmpc) based on wiener model and laguerre function is proposed in [9]. employing a wiener model in nmpc can handle the nonlinearity in the controlled cstr plant and retain all important properties of linear model predictive control (mpc) with a quadratic function. the main advantage of the presented approach is not necessary to use a combined structure of identification and decision, common in a standard self-tuning controller because it is used a particle swarm optimization (pso) as a simple steps algorithm and fast tuning the parameters of the pid controller. the remainder of this paper is organized as follows: section two is a description of the mathematical model of the cstr. in section three, the proposed of neural network like selftuning pid controller approach and tuning algorithm are derived. simulation results of the proposed adaptive pid neural control algorithm are presented in section four and the conclusions are drawn in section five. 2. cstr mathematical modeling consider standard two-state (cstr) with an exothermic irreversible first-order reaction ba → take place, the heat of reaction is removed by a coolant medium that flows through a jacket around the reactor as shown in figure (1) [10 and 11]. the dynamics of system can be described by the following two nonlinear ordinary differential equations [10, 11, 12 and 13]: ))((1)( )()( ))(( )( )())(( )( )( )( )( tttetq volc c e c tckh ttt vol q t tt etcktcc vol q t tc cf ctq h c cc cc trt e ao f trt e aoaaf a ccc a −×           −× ×× × + × × ××∆− +−= ∂ ∂ ××−−= ∂ ∂         ×× −       −       − ρρ ρ ρ ρ ρ ρ ρ …(1) fig .1. cstr with cooling jacket. the nominal cstr operating conditions can be shown in table (1). q c (t) , t cf coolant c af , q , t f reactant q c (t) , t c (t) c a (t) , q , t(t) product khulood a. dagher al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 4653(2013) 48 table , nominal cstr operating conditions. parameter description nominal value q process flow-rate 100 lmin -1 caf intel feed concentration 1 mol l -1 tf feed temperature 350k tcf inlet coolant temperature 350k vol reactor volume 100 l ha heat transfer coefficient 7*10 10 cal min 1 .k -1 ko reaction rate constant 7.2*10 10 min -1 r e activation energy 9.95*10 3 k h∆ heat of reaction 2*10 5 cal mol -1 c,ρρ liquid densities 1000 g l -1 cp cpc specific heats 1 cal g -1 . k -1 qc coolant flow-rate 103.41 l.min -1 t reactor temperature 440.2k ca product concentration 8.36*10 -2 mol l 1 3. pid neural controller approach the approach used to control the nonlinear system depends on the information available about the system and the control objectives; therefore, the general structure of the pid neural controller is shown in figure (2). the feedback pid neural controller is very important because it is necessary to stabilize the tracking error of the system when the output of the system is drifted from the reference point. the self-tuning pid neural controller is shown in figure (3). it is based on a conventional pid controller, which consists of three terms: proportional, integral and derivative. the standard form of a pid controller is given in the s-domain as in equation (2) [15]. sk s k kdipsgc d i p ++=++=)( …(2) where kp, ki and kd are called the proportional gain, the integral gain and the derivative gain respectively. the aim of adaptive self-tuning technique is to adjust the parameters of the pid neural controller by using particle swarm optimization algorithm technique. the proposed self-tuning pid neural control scheme is like neural network pid controller structure as the discrete-time equation (3) [16]. )()]1()([)1()( kkiekekekpkuku +−−+−= )]2()1(2)([ −+−−+ kekekekd ….(3) therefore, the self-tuning pid input vector consists of e(k), e(k-1), e(k-2) and u(k-1), where e(k) and u(k-1) denote the input error signals and the self-tuning pid output respectively. cstr system pid controller particle swarm optimization algorithm kp ki kd caref(k+1) e(k) u(k) caout(k+1) + fig. 2. the proposed block diagram of neural network like self tuning pid controller. u(k-1) khulood a. dagher al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 4653(2013) 49 fig. 3. the neural network like self tuning pid controller architecture. 3.1. learning algorithm particle swarm optimization is a kind of algorithm to search for the best solution by simulating the movement and flocking of birds. pso algorithms use a population of individual (called particles) “flies” over the solution space to search for the optimal solution. each particle has its own position and velocity to move around the search space. the particles are evaluated using a fitness function to see how close they are to the optimal solution [17, 18 and 19]. the previous best value is called as pbest. thus, pbest is related only to a particular particle. it also has another value called gbest, which is the best value of all the particles pbest in the swarm. the neural network like self-tuning pid controller with three weights parameters of the pid controller matrix is rewritten as an array to form a particle. particles are then initialized randomly and updated afterwards according to equations (4, 5, 6, 7, 8 and 9) [17, 18 and 19] in order to tune the pid parameters: )()( 2211 1 k m kk m k m k m k m kpgbestrckppbestrckpkp −+−+∆=∆ + …(4) 11 ++ ∆+= k m k m k m kpkpkp …(5) )()( 2211 1 k m kk m k m k m k m kigbestrckipbestrckiki −+−+∆=∆ + …(6) 11 ++ ∆+= k m k m k m kikiki …(7) )()( 2211 1 k m kk m k m k m k m kdgbestrckdpbestrckdkd −+−+∆=∆ + …(8) 11 ++ ∆+= k m k m k m kdkdkd … ( 9 ) popm ,.....3,2,1= where pop is number of particles. k mkpid is the weight of particle m at k iteration. c1 and c2 are the acceleration constants with positive values equal to 2. r1 and r2 are random numbers between 0 and 1. mpbest is best previous weight of m th particle. gbest is best particle among all the particle in the population. the number of dimension in particle swarm optimization is equal to three because there are only three parameters of the pid controller. the mean square error function is chosen as criterion for estimating the model performance as equation (10): 2 1 ))1()1(( 2 1 ∑ = +−+= pop j j out j ref kcakcae …(10) the steps of pso for neural network like selftuning pid controller can be described as follows: • step1 initial searching points 0 1kp , 0 1ki , 0 1kd , 0 1kp∆ , 0 1ki∆ and 0 1kd∆ of each particle are usually generated randomly within the allowable range. note that the dimension of search space is consists of all the parameters used in the neural network like pid controller as shown in figure (3). the current searching point is set to pbest for each particle. the best-evaluated value of pbest is set to gbest and the particle number with the best value is stored. • step2 the objective function value is calculated for each particle by using equation (10). if the value is better than the current pbest of the particle, the pbest value is replaced by the current value. if the best value of pbest is better than the current gbest, gbest is replaced by the best value and the particle number with the best value is stored. • step3 the current searching point of each particle is update by using equations (4, 5, 6, 7, 8 and 9). • step4 if the current iteration number reaches the predetermined maximum iteration number, then exit. otherwise, go to step 2. 4. simulation results the dynamic model of the cstr described in section 2 is used where the objective is to control the ca(t), which can be done by introducing a coolant flow rate qc(t) as the manipulated variable, also the temperature can be varied too. to study the dynamic behavior of the cstr kp + + + + )(ku + + + + ki kd )(ke )1( −ke )2( −ke )1( −ku 1 -1 1 1 -2 1 1 khulood a. dagher al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 4653(2013) 50 model, the open loop output response of the cstr for step changes in the coolant flow-rate is shown in figures (4-a & b) respectively by using the fourth order rk method [20] with sampling time of 0.1 minute through the matlab/simulink computer simulation. 0 20 40 60 80 100 120 140 160 180 200 0.06 0.065 0.07 0.075 0.08 0.085 0.09 0.095 0.1 0.105 sample c s t r o u tp u t c a ( m o l/ l) fig. 4-a. the open loop respose of the cstr. 0 20 40 60 80 100 120 140 160 180 200 94 96 98 100 102 104 106 108 110 sample c o o la n t fl o w -r a te ( l/ m in ) fig. 4-b. the step changes in the coolant flowrate. as shown in figure (4), both the damping and the steady-state gain of the system varies considerably, depending on the set point, which gives an indication of the highly nonlinear dynamic behavior of the system. the proposed neural network like self-tuning pid controller scheme as in figure (2) is applied to the cstr model and it is used the proposed learning algorithm steps of pso for tuning pid controller's parameters. the pso algorithm is set to the following parameters: population of particle is equal to 20 and number of iteration is equal to 300.number of in each particle is 3 because there are three parameters of pid. it is very necessary to normalize the input signals of figure (4-a) and the coolant flow-rate as the manipulated variable of figure (4-b) between (-1 to +1). the signals entering to or emitted from the network have been normalized to lie within (-1 to +1) in order to overcome numerical problems that is involved within real values. scaling functions have to be added at the neural network terminals to convert the scaled values to actual values and vice versa. after training, it can be observed that the actual output of the cstr plant is following the desired input that is shown the figure (5) while the feedback control action is shown in figure (6) that has small spike in the transit state and fix output at steady-state. 0 50 100 150 200 250 300 0.075 0.08 0.085 0.09 0.095 0.1 sample c s t r o u tp u t c a m o l/ l desired input actual output fig. 5. response of the cstr plant output & the desired input. 0 50 100 150 200 250 300 80 85 90 95 100 105 110 115 120 sample c o o la n t fl o w -r a te fig. 6. the feedback pid control signal. the error between the desired input and the actual output of the plant is very small as shown in figure (7). khulood a. dagher al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 4653(2013) 51 0 50 100 150 200 250 300 -8 -6 -4 -2 0 2 4 6 8 10 x 10 -3 sample e r r o r fig. 7. output error between the set point desired & the actual output. the gains of the pid self-tuning neural controller as scale function is shown in figure (8). 0 50 100 150 200 250 300 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 sample p id p a r a m e te r s kp gain ki gain kd gain fig. 8. the pid controller's parameters. 5. conclusion in this paper, the structure of the neural network –like self tuning pid controller with particle swarm optimization algorithm technique learned as the proposed structure of controller and successfully simulated to nonlinear dynamic cstr system. using pid feedback controller with self-tuning technique to adjust the parameters (kp, ki, kd) of the controller. so that, the output of the plant follows the desired input and pso algorithm is used to tune the pid controller with minimum time and more stability of the controller and no oscillation with best parameters of the controller. the proposed control structure has shown the ability to minimize the tracking error in the transient state less than 0.01 between the desired input and the actual output of the cstr plant and in the steady state, the tracking error is equal to zero, as well as to reduce the spike control action with a simple and fast training algorithm. acknowledgment the authors would like to express their appreciation to automation and robotics research unit (arru) at control and systems engineering dept. in the university of technology for providing them the requirements of this research. 6. references [1] t. wonghong and s. engell, real-time pi controller tuning via unfalsified control, the proceedings of ieee international symposium on intelligent control (isic), part of 2011 ieee multi-conference on systems and control denver, co, usa. september 28-30, 2011, pp. 1008-1013. [2] r. gao, a. odywer and e. coyle, a nonlinear pid controller for cstr using local model networks, proceedings of the 4th world congress on intelligent control and automation june 10-14, 2002, shanghai, p.r.china., pp. 3278-3282. [3] x. zhicheng, the application in adaptive control for differential evolution algorithm, proceedings of the international conference on system science, engineering design and manufacturing information, 2011, pp. 206209. [4] u. sabura and g. uma, fuzzy gain scheduled pole placement based state feedback control of cstr, iet-uk international conference on information and communication technology in electrical sciences (ictes 2007), dr. m.g.r. university, chennai, tamil nadu, india. dec. 20-22, 2007. pp.63-68. 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[15] q. zhong, "robust control of time-delay systems", springer – verlag london limited 2006 [16] s. omatu, m. khalid, and r. yusof, neurocontrol and its applications. london: springer-velag, 1995. [17] j. derrac, s. garc, d. molina and f. herrera ,a practical tutorial on the use of nonparametric statistical tests as a methodology for comparing evolutionary and swarm intelligence algorithms, journal of swarm and evolutionary computation, vol.1,pp. 3–18, 2011. [18] j. zhou, z. duan, y. li, j. deng and d. yu, pso-based neural network optimization and its utilization in a boring machine, journal of materials processing technology, vol.178, pp.19–23, 2006. [19] y.s. lee, s.m. shamsuddin, and h.n. hamed, bounded pso vmax function in neural network learning, proceedings of the eighth international conference on intelligent systems design and applications, pp.474-479, 2008. [20] k. ogata, modern control engineering. 4th edition, by addisonwesley publishing company, inc. 2003. )2013( 46-53، صفحة 4، العدد9مجلة الخوارزمي الھندسية المجلد خلود اسكندر داغر 53 متكيف لخزان مفاعل مستمر ا*ثارة مبني على أساس) pid(تصميم مسيطر عصبي أمثلية حشد الجسيمات *خلود اسكندر داغر **أحمد صباح ا5عرجي جامعة بغداد/ كلية العلوم / قسم علوم الحاسبات * التكنولوجيةالجامعة / ھندسة السيطرة والنظم قسم** dagherkhulood@yahoo.com : ا'لكتروني البريد * ahmedsas2040@yahoo.com : ا'لكتروني البريد ** الخ7صة ذات التنغيم التلقائي لمنظومة خزان مفاعل مستمر ) pid(مع الشبكة العصبية التي تشبه المسيطر أن ھذا البحث يقدم خوارزمية أمثلية حشد الجسيمات . ا<ثارة تتم من خeل تقنية خوارزمية حشد الجسيمات cنھا ) pid(مبني على أساس الشبكة العصبية و تنغيم عناصر المسيطر ) pid(أن ھيكلية المسيطر .ھذه الطريقة المقترحة ھي ' تحتاج إلى عملية التعريف للمنظومة بسبب استخدام أمثلية حشد الجسيماتأن فائدة .بسيطة و سريعة التعلم المتكيف من حيث اقل خطأ تتابعي و الحصول على أشارة سيطرة ) pid(من خeل نتائج المحاكات نeحظ فعالية ھذه الخوارزمية للمسيطر العصبي . رفناعمة لمنظومة ديناميكية 'خطية التص سيسيليا وبسمة ومحمد al-khwarizmi engineering journal, vol. 9, no. 4, p.p. beneficiation of iraqi akash for the production of c.kh. haweel* basma a. *,**,***department of chemical engineering ** email: *** email: (received 29 september 2013; accepted abstract in the present work, leaching process studiedusing organic acids from the iraqi akashat phosphate ore by separation of calcareous materials (mainly calcite). this approach characterized by energy conservation, environmental enhancement by recovery of calcite as calcium sulfate (gypsum), keeping the physical and chemical properties of apatite. spectrophotometer. from the obtained experimental data it was found that purity values of the produced apatite at the optimum conditions, while at different acid concentrations, it was found that the efficiency of acetic acid is higher at the low efficiency at high acid concentration (10 wt%) reducing this ratio to 5 ml/gm cause an increase in the purity of apati in addition, it was found that the reaction ofthe two optimum reaction time, in which high purity apatite produced is keywords: iraqi akashatphosphate ore, selective leaching, beneficiation, 1. introduction to meet the food needs of the increasing world population, there is a steadily growing demand for phosphate fertilizers. the phosphoric acidproduction is directly linked to the phosphate fertilizer consumption, which is continuously rising.this represents an increase of the phosphoric acid production. phosphate rocks are vital non-renewable resources and essential components in fertilizers and phosphorous-based chemicals. it is neither substitutable nor recyclable, therefore, the total demand mustbe provided through the mining, beneficiation and chemical processing of natural resources of this ore. phosphate deposits may be divided in three major groups, according to their origin: khwarizmi engineering journal, vol. 9, no. 4, p.p. 2438 (2013) akash at phosphate ore using organic acids production of wet process phosphoric acid basma a. abdul-majeed ** mohammed y. eisa department of chemical engineering / college of engineering / university of baghdad *email: cicil@yahoo.com email: basma1957@yahoo.com email: mohammedyeisa@yahoo.com september 2013; accepted 12 january 2014) process studiedusing organic acids (acetic acid and lactic acid) to extract phosphate from the iraqi akashat phosphate ore by separation of calcareous materials (mainly calcite). this approach energy conservation, environmental enhancement by recovery of calcite as calcium sulfate (gypsum), keeping the physical and chemical properties of apatite. samples were analyzed using x-ray diffraction and ftir experimental data it was found that using the two organic acids yields closed purity values of the produced apatite at the optimum conditions, while at different acid concentrations, it was found that the efficiency of acetic acid is higher at the low acid concentration (2 wt%), and that lactic acid gives the higher (10 wt%).concerning the ratio of acid volume to ore weight ratio, reducing this ratio to 5 ml/gm cause an increase in the purity of apatite at the optimum concentrations of the two acids. t was found that the reaction ofthe two organic acids with the calcareous material are optimum reaction time, in which high purity apatite produced is 10 minutes. elective leaching, beneficiation, calcareous phosphate ore, organic acids to meet the food needs of the increasing world population, there is a steadily growing demand for the phosphoric acidproduction is directly linked to the phosphate fertilizer consumption, which is continuously rising.this represents an increase of the renewable s in fertilizers based chemicals. it is neither substitutable nor recyclable, therefore, the total demand mustbe provided through the mining, beneficiation and chemical processing of natural . phosphate deposits may be divided in three major groups, according to their 1. deposits from sea sediments. 2. igneous and metamorphic deposits. 3. biogeneticdeposits. it should be mentioned that most of world's phosphate resources are of depositorigin [1,2]. apatite (the desired component in phosphate rock) has the general formula, where x is typically f(fluorapatite, (hydroxyapatite, ohap), or cl clap). the apatite lattice is very tolerant of substitutions, vacancies and solid solutions, for example, x can be replaced by ½co by sr, ba, pb, na or vacancies; and aso4, vo4, sio4 or co3 [3]. in sedimentary deposits of marine origin, the phosphate material occurs in admixtures with detritus materials such as quartz, mica and clay, al-khwarizmi engineering journal using organic acids cid mohammed y. eisa*** university of baghdad to extract phosphate from the iraqi akashat phosphate ore by separation of calcareous materials (mainly calcite). this approach energy conservation, environmental enhancement by recovery of calcite as calcium sulfate (gypsum), ray diffraction and ftir using the two organic acids yields closed purity values of the produced apatite at the optimum conditions, while at different acid concentrations, it was found that , and that lactic acid gives the higher , it was found that te at the optimum concentrations of the two acids. fast and that the calcareous phosphate ore, organic acids) igneous and metamorphic deposits. it should be mentioned that most of world's of sedimentary (the desired component in phosphate has the general formula, ca10(po4)6x2 (fluorapatite,fap), oh cl (chlorapatite, clap). the apatite lattice is very tolerant of substitutions, vacancies and solid solutions, for ½co3 or ½o; ca or vacancies; and po4 by hpo4, ts of marine origin, the phosphate material occurs in admixtures with detritus materials such as quartz, mica and clay, mailto:cicil@yahoo.com mailto:basma1957@yahoo.com mailto:mohammedyeisa@yahoo.com c.kh. haweel al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 2438 (2013) 25 often with limestone and occasionally with dolomite. igneous apatitemay contain other impurities, not commonly found in sedimentary deposits, originating from other constituents of the magma from which the apatite crystallized[4]. phosphate deposits in iraq are part of a wide arab phosphate which stretches frommauritania in the west to iraq and saudi arabia in the east through north africaand eastern mediterranean sea. the most important of these formations is akashat phosphate layer, thickness of upto ten meters in which the proportion of phosphorus pent-oxide between 21-22%which can be increased to more than 25% by simple physical methods. phosphatedeposits in sedimentary layers appears freely with limestone and clay stone [5]. the phosphoric acid production is directly linked to the phosphate fertilizer consumption, which is expected to rise. it can be produced from phosphate ore via two major process routes, the so-called wet processes, using strong mineral acids for digestion of the ore and the dryprocesses, producing elemental phosphorus as an intermediate by burning of the ore in an electric furnace or in a rotary kiln. since phosphoric acid produced through dry routes contains less impurities its application lies mainly in the "high added value" areas such as detergents and food additives, while phosphoric acid from wet processes is mainly further processed into fertilizers. in the dry processes, the phosphate ore is reduced, by addition of silica and carbon, to phosphorus and slag at about 1500°c in a furnace: ( ) + 20 + 28 → 20 + 28 + 3 + 2 …(1) δh = 27.9 mj/kg of p4produced [6] although the heat of combustion of the phosphorus and the carbon monoxideis recovered in the dry process, these processes are still too expensive for usein the fertilizer industry. in the wet processes, phosphoric acid can be released from phosphate ore by the action of strong mineral acids, such as nitric acid, hydrochloric acid and sulfuric acid. sulfuric acid is the only acid, which forms an insoluble precipitate with thecalcium from the phosphate ore, thus allowing the phosphoric acid to beseparated directly by filtration according to the reaction: ( ) + 10 → 6 + 10 + 2 …(2) the chlorides and nitrates of calcium are bothsoluble, so special techniques, like solvent extraction, ion exchange or cooling crystallization are required to recover the phosphoric acid [7]. in spite of this, phosphoric acid is being commercially produced using nitricacid as well as hydrochloric acid. the economical feasibility of these processesis mainly determined by the availability, price of the mineral acid,local production facilities and by the desired products. phosphate ore requires processing to reduce the content of gangue minerals such as carbonates, silicates, feldspar, mica, calcite, dolomite and clays to meet the requirements of the phosphate industry [8]. the marketable sedimentary and igneous phosphate ore usually has 28–36% and 35–39% p2o5 respectively. phosphate ores should notcontain more than 8% carbonates in order to be economical [9]. it is necessary in the fertilizer industry for the phosphate ores to have: § p2o5content larger than 30%. § cao/p2o5 ratio smaller than 1.6, § mgo content less than 1% and fe2o3 and al2o3 content: maximum 2.5% [10]. effective beneficiation can be achieved by various processes, depending upon the liberation size of phosphate and gangue mineralsand other ore specifications. different processes like screening,scrubbing, heavy media separation, washing, roasting, calcinations,leaching and flotation may be used. the presence of free carbonates in the phosphate rocks usuallyrequires additional acid (sulfuric acid) during the manufacture ofphosphoric acid and superphosphates by the “wet process”. inaddition, the carbon dioxide produced during the acid addition causesmore foaming and results the production of smaller size gypsumcrystals that may blind the downstream phospho-gypsum filters.hence, a low quality phosphoric acid is produced [11]. the beneficiation of sedimentary phosphate ores containing carbonategangue is a worldwide problem and adequate technology forprocessing such ores on an industrial scale does not exist at present. calcination is used in areas having low cost energy and limitedwater resources like the aljalamid phosphate ore in saudi arabiawhich contain 40–50% carbonate, 8–10% organic matter and 16–25%p2o5. it is processed by calcination at 850 °c for about 1 h, followed byleaching with water to remove lime and quenching by 5% nh4no3 toremove magnesium [12]. calcinationis c.kh. haweel al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 2438 (2013) 26 a thermal decomposition of calcareous material. depending onthe process conditions, calcination may lead to almost complete eliminationof the carbonate gangue that existed in the phosphate ore. flotation of calcareous phosphate ores may be effective only if the phosphate particles are highly liberated from the gangue materials and exhibit a relatively coarse size. the flotation process seems to work best on ores containing well crystallized carbonates. when the ore contains soft or chalky carbonates, the results are less satisfactory [13]. with regard to the problems with sedimentary phosphate ores, acid leaching is a promising method that can be applied to treat thecalcareous phosphate ores and more attention being given to leaching methods. since nearly 80% of the world's phosphate resources are calcareous ores, including akashat iraqi ore, an experimental work is to be adapted to specify the suitable operating conditions of beneficiation. the selected leaching agents should not attack the phosphate minerals, but unfortunately, strong acids also attack the apatitewhile leaching the carbonates.however,weak organic acids show an appreciable degree of selective leaching of calcareous material in low grade phosphate rocks and ores [14]. organic acids are selective leaching agents for the beneficiation of low grade phosphate rock, depending on the reaction conditions, nature and size of the particles.although organic acids are promising leaching agents, there are some restrictions in the selection of the organic acids and this beneficiation method has some drawbacks that should be taken into consideration. using this leaching method, many of the problems encounteredduring the manufacture of phosphoric acid and superphosphates areresolved. at the same time, both calcium and magnesium carbonatesare removed in the form of highly soluble salts. the reaction timeneeded for leaching is small, thus the destructive action of dilute organicacid on the phosphate minerals is minimum. typically, organic acidextractions are carried out undermoderately acidic conditionsand their degradation is biologically easy.furthermore, in industrial processes, organic acids cause a littlecorrosion [13]. due to the previous mentioned information, an experimental comportment study is to be conducted on iraqi akashat phosphate ore to separate the calcareous gangue materials (mainly calcite) using organic acids leaching (acetic and lactic) to specify the optimum conditions that give a marketable phosphate ore with the necessary (p2o5) content as a raw material of wet process phosphoric acid required for fertilizers industry. 2. chemistry of leaching in the case of acetic acid, the reaction between acetic acid and calcareous materials can be written as follows [9]: ( ) + 2 ( ) → ( ) ( ) + ( ) + ( ) …(3) the acid ratio (used/stoichiometric) is the ratio of the used amountof acetic acid and the required amount for reaction (3). the stoichiometryis determined by using the following equation [20]: acidstoichiometry = (mol. of ch3cooh) / (mol. of co2)= 2:1 completion of this reaction depends on the product solubility, aceticacid concentration, process temperature, reaction time and otherprocess conditions. however, the dissolution kinetics could alsocontrol the overall rate of selective leaching of calcareous minerals inthe phosphate rocks and ores. the mechanism of carbonate dissolution in acetic acid solutioninvolves the initial formation of ca(ch3coo)2 and carbonic acidwhich decomposes into co2 and h2o. if the acetic acid expresses noselectivity, then the following reaction may occur: ca10(po4)6f2+20ch3cooh= 10ca+2+20ch3coo−+2hf+(6−x)h3po4+xh2po4 -+xh+ …(4) however, acetic acid should not attack the phosphate minerals andthus reaction (4) does not take place while reaction (3) proceeds tocompletion. similarly, in the dissolution of carbonate minerals using lactic acid,the reaction between lactic acid and calcareous material is as follows: ( ) + ( ) ( ) → ( ( ) ) ( ) + ( ) + ( ) …(5) under normal conditions, reaction (5) may be considered as anirreversible reaction due to the removal of co2 produced during theprocess by stirring the reaction mixture. the reactions for the otherimpurities depend on the nature and composition of the raw phosphateore. the simplest mechanism for the rational understanding oftheselective leaching process can be expressed as follows [15]: c.kh. haweel al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 2438 (2013) 27 ( ) + 2 ( ) → ( ) + ( ) + ( ) …(6) ( ) ( ) + 6 ( ) → 3 ( ) + 2 ( ) …(7) where:m=ca+2 and/or mg+2, andx=ch3ch(oh)coo− (lactate) or ch3coo (acetate). again, the acid should not attack the phosphate minerals andthus reaction (7) does not take place while reaction (6) proceeds tocompletion or equilibrium depending on the solubility products (ksp=8.35, 7.46 for caco3 and mgco3, (respectively) and acidity constants forlactic acid (pka=3.86 at 25 °c) and co2 (pk1=6.35, pk2=10.33 forh2co3). the main factors investigated by researchers were: leachingreagent, acid concentration, reaction time, liquid/solid ratio (pulpsolid percent); temperature, particle size distribution, stirring speedand type and nature of the ore. the organic acids most commonly used in carbonate leaching are:acetic acid, lactic acid, formic acid and succinic acid which are all fullymiscible with water, although succinic acid has a lower solubility(67 g/l at 22 °c) and is limited by its solubility at low temperatures.the fully miscible acid salts are soluble in water and can be easilyseparated from the beneficiated solid phosphate product by filtration. in the weak organic acids, the increasing concentrations of organicacids cause little increase in the solution acidity because they are onlypartially dissociated in aqueous solution. for example, 1.0 m aceticacid has a ph of 2.4, indicating that merely 0.4% acetic acid moleculesare dissociated. according to the literature, all the organic acids give good results forthe selective leaching of calcareous material. acetic and formic acidsmay cause corrosion effects on the equipment, alongwith a tendency toattack the phosphate minerals,whilst lactic acid causes less corrosion onthe equipment with minimal risk of phosphate mineral dissolution.it is reported that by dilution of the acid with water, the surfacearea of contact between the acid and the carbonates will increase [16]. highly concentratedorganic acid solution does not react with calcium carbonate because ofthe large polarity of the o–h bond of the acid molecules and it isnecessary to use dilute solution for an effective reaction. in dilutesolutions, water molecules tend to decrease the effect of polarity ofthe organic acids o–h bond [15]. the dilute organic acids are also less destructive if someof the produced solution is added or recycled to the process [16]. acid concentration is one of the key factors in achieving good resultsin the selective dissolution of calcareous mineral in phosphate ores. ingeneral, the p2o5 content increases with increasing acid concentrationto reach a certain level, and then remains almost constant. under optimum concentrations, there are no physical or chemicalchanges in the phosphate rock, or losses of its tri calcium phosphate (tcp) content. there are differences in the optimum organic acid concentrationsreported in previous studies which could be attributed to the differences inorigin of the various sedimentary resources. the acid concentrationthat gives the best leaching result has been found to depend on acidtype, carbonates mineral content and the liquid/solid ratio [13]. the effect of reaction time on the dissolution of carbonate mineralsin the leaching process was studied by many investigators. it is clear thatwith increasing reaction times up to an optimum value, the p2o5percentage increases along with the corresponding reduction in calcareousmaterials content. at the optimum time, the reaction eitherreaches equilibrium or is prevented from further leaching because ofthe formation of a solid product. investigatorsmentioned the value ranges from 45 to 60 min for effectivedissolution;it appears that the optimum leaching time varies from 30to 60 min. it is concluded that the time required to minimize the carbonate content depends on the size of the phosphate particles, thenature of the adherent materials in the phosphate rock and otherprocess conditions [13]. the leaching rate of carbonate minerals and its efficiency also associated with the increase in surface area and the liberation of more calcareous material from the phosphateminerals matrix. 3. mathematical model box–wilson statistical experimental design was employed to determine the effects of operating variables on phosphate recovery and to find the combination of variables resulting in maximum recovery. the box–wilson design is a response surfacemethodology which is an empirical modeling technique devoted to the evaluation of the relationship of a set of controlled experimental factors and observed results. basically this optimization process involves three c.kh. haweel al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 2438 (2013) 28 major steps; performing the statistically designed experiments, estimating the coefficients in a mathematical model and predicting the responsewith checking the adequacy of the model [17]. this design consists of (2 ) factorial points (coded to the ∓1 notation), augmented by 2p axial points (∓∝, , ), ( ,∓∝, ), ( , ,∓∝) and center points (0,0,0). a central composite design is made rotatable by the choice of (∝). the value for rotatability depends on the number of variables p (i.e. for p=2, ∝= √ = 1.414 and for p=3, ∝= √3 = 1.732).the relation between the coded levels and the corresponding real variables is shown in equation (8): = ( ) . …(8) where: p=no. of variables the number of experiments (n), needed is estimated using eq. 2: = 2 + 2 + 1 …(9) thus for three variables design, the number of experiments needed according to eq. (9) is (15) plus 3 experiments around the center point to certify the relation. acid concentration (c) in weight percent, liquid volume to solid weight ratio (l/s) in ml/gm and leaching time (t) in min., were considered as independent variables and designated as x1, x2 and x3 respectively. phosphate recovery was considered as dependent variables in the box–wilson statistical design method. the acid concentration (x1) was varied between 2 and 10 weight percent, the ratio (x2) of acid liquid volume (ml) to ore weight (gm) between 5 to 15 (ml/gm) and the time (x3) between 10 and 90 min. according to eq.(8) the relation between the coded levels and the corresponding real variables shown as follows: = ( . ) …(10) = ( . ) …(11) = ( . ) …(12) experimental conditions determined by the box–wilson statistical design are presented intable 1. the experiments consist of six axial (a), eight factorial (f) and center point. the centerpoint (experiment no. 15) was repeated four times and the mean is taken. table1, experimental conditions according to a box-wilson experimental design. no coded values real values x1 x2 x3 wt % (l/s) time (min) 1 +1 +1 +1 8.3 12.9 73 2 -1 +1 +1 3.7 12.9 73 3 +1 -1 +1 8.3 7.1 73 4 -1 -1 +1 3.7 7.1 73 5 +1 +1 -1 8.3 12.9 27 6 -1 +1 -1 3.7 12.9 27 7 +1 -1 -1 8.3 7.1 27 8 -1 -1 -1 3.7 7.1 27 9 +α 0 0 10 10 50 10 0 +α 0 6 15 50 11 0 0 +α 6 10 90 12 -α 0 0 2 10 50 13 0 -α 0 6 5 50 14 0 0 -α 6 10 10 15 0 0 0 6 10 50 computation was carried out using multiple regression analysis using the least squares method. the resulting equation (13) represents response function, was used in correlating the phosphate recovery (pr) and calcite removal efficiency (cr) with independent parameters (x1, x2, x3). = + + + + + + + + + …(13) the statistica 5.5 release computer program was employed for the determination of the coefficients of (eq.1) by regression analysis of the experimental data for each variable using rosenbrock and quasi-newton method; where y is predicted recovery, b0 is constant, b1,b2,b3 are linear coefficients, b12,b13,b23 are cross product coefficients andb11,b22,b33are quadratic coefficients. c.kh. haweel al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 2438 (2013) 29 4. sample preparation and analysis in order to identify the behavior of the phosphate bearing minerals and theassociated impurities with respect to particle size, representative samples of thephosphate (crushed to -10mm particle size) was subjected to dry sieving.all of the samples were dried in an electric oven at about 105 °c for 2 hrs, cooled to room temperature and stored in closed desiccators. each size fraction obtained was weighed and analyzed in terms ofapatite and calcite. the distribution percentages were calculatedaccordingly. the results obtained are tabulated as shown in table 2. these sample fractions were characterized by x-ray powder diffraction (model lab-x, xrd 6000, shimadzu, japan) in the national center for construction laboratories and research, ministry of construction and housing. then analyzed using ftir spectrophotometer (model iraffinity-1, shimadzu, japan) in the environmental central laboratory, college of science, university of baghdad. table 2, particle size distribution of the studied phosphate. fraction (mm) weight % cumulative distribution calcite rir % apatite rir % +0.6 29.13 76 24 +0.3 13.01 61.31 38.69 +0.15 20.05 62.67 37.33 +0.125 11.99 65.79 34.21 +0.075 13.05 76 24 -0.075 (base) 12.77 81.65 18.35 x-ray diffraction (xrd) spectrometry is one of the most powerful analytical tools available for identifying unknown crystalline substances. all crystals are composed of regular, repeating planes of atoms that form a lattice. when coherent xrays are directed at a crystal, the x-rays interact with each atom in the crystal, exciting their electrons and causing them to vibrate with the frequency of the incoming radiation. the electrons become secondary sourcesof x-rays, reradiating this energy in all directions at the same wavelength as the incident beam, a phenomenon called coherent scattering. these secondary or diffracted x-rays, which can be thought of as waves traveling in all directions, form interference patterns, much like interference patterns formed by dropping two rocks into water. this interference may be constructive, forming larger waves, or destructive, canceling out the waves entirely. the pattern of interference created depends on the distance between atomic layers, chemical composition, and the angle that the xrays diffract away from the atoms, thus it indirectly reveals a crystals structure. using an xrd spectrometer, the diffraction pattern created by constructive interference is recorded by a beam detector as the x-ray tube and the detector are rotated around the sample. the relationship between angle at which diffraction peaks occur 2 and the inter-atomic spacing of a crystalline lattice (d-spacing) is expressed by bragg’s law: nλ = 2d sin . for historical reasons, xrddiffractograms, are expressed in degrees two theta (2 ). since each crystalline structure is unique, the angles of constructiveinterference form a unique pattern. by comparing the positions and intensities of the diffraction peaks against a library of known crystalline materials, samples of unknown composition can be identified. this works even with mixtures of materials, where each separate crystalline material can be identified and semiquantified. fourier transform infrared (ftir) spectroscopy is apowerful analytical technique for the characterization ofmaterials. thus, to distinguish the presence of a specific group (bond) and also the degree of probable separation of a reacted component during acid treatment, ftir analysiswas performed in the present investigation. the measurements were carried out in the transmissionmode in the mid-infrared range with wave numbers 400 cm-1 to 4000 cm-1, ftir samples were first ground in a mortar, in a mannersimilar to that used in the preparation of xrdsamples, and then mixed with kbr powder in a ratio of1:100, followed by forming a pellet by using a uniaxialcold press. 5. experimental procedure for selective leaching studies, phosphate ore of(-0.15+0.30mm) size fraction was used in a well mixed three necked funnel glass batch reactor of (500 ml) size, equipped on a magnetic stirrer c.kh. haweel al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 2438 (2013) 30 having a controller unit. a known amount of acetic acid with a specific concentration (in weight%) and liquid/solid (l/s) ratio was slowly pipetted into the reactor vessel containing 10.0g of the sample for a specific time each run according to the set of experiments shown in table (1). temperature for all experiments fixed on 30oc to prevent crystallization of calcium acetate at higher temperatures. mixing speed found to be efficient at 300 rpm to ensure steady dispersionof particles in the liquid phase. at the end of each reaction, the reaction vessel was immediately stopped mixing to end the reaction before the separation of the leach slurry by vacuum filtration. the same procedure repeated using lactic acidto specify the best results. the resulting samples were then dried, weighed and analyzed by x-ray diffraction in order to show the difference in composition. to confirm the results for the efficiency of beneficiation, the solid phase after the leaching process was also analyzed by ftir spectroscopy. 6. xray diffraction apatite can be identified by a highest intensity peak located at approximately (2 ) 31.9o, closely followed by three more high intensity peaks located between (2 ) 32o and 34o. apatite also has weaker intensity diagnostic peaks located at approximately (2 ) 26oas shown in figs. 1 and2. the locations and intensities of these peaks clearly differentiate apatite from the vast majority of the study materials that are for the most part composed of calcium carbonates, silicates, or sulfates. for example, plaster of paris (gypsum), charcoal ash, wood ash and both kinds of sheetrock all lack peaks near (2 ) 11o, calcite lack peak near (2 ) 29.4o. if a sample lacks any of the diagnostic peaks listed and/ or the relative peak heights are significantly different, then the sample is not apatite, or the sample is contaminated [18]. to give more details on the characterization runs,samples for xrd analyses were first ground in an agatemortar using an agate pestle and then sprinkled ontoethanol-damped single-crystal quartz sample holders toform a thin layer, followed by tapping to remove excess powder. the xrd was operated at 40 kv and 30ma with monochromated cukaradiation. xrd data over the range of angle (2 =20–50o) were collected with a step size of 0.05 degree and a preset time of 0.75 sec at each step. table 4 shows the relative intensity ratio (rir) of each main component of the ore [19]: % = ∑ × 100% …(14) where: ii= main peak intensity of component (i) fig. 1. x-ray diffraction of the mixed size samplephosphate ore (before acid leaching). fig. 2. x-ray diffraction of (0.15-0.30 mm) fraction phosphate ore (before acid leaching). 7. ftir analysis fig.3 shows the ftir spectra of the mixed size phosphate ore. in all the obtained spectra, po4 absorptionbands were observed at 1,000–1,100 cm−1 and 550–600cm−1, which were assigned to po4 3− ion in the apatitelattice. absorption band at 1,400–1,500 cm−1 wasassigned to co3 2− ion in the apatite lattice.appearance of co3 2− peak indicated that the apatitephase was cap (calcite-apatite). c.kh. haweel al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 2438 (2013) 31 two types of cap exist with respect tothe substitution site of co3 2− ion in the apatite lattice. one is a-type cap, in which co3 2− groups substitutedoh. for b-type cap, co3 2− groups substitutedthe po4. in the present study, the obtainedspectra were typically those of b-type cap, in which theabsorption band of co3 had two maxima at 1,455 cm−1and 1,410 cm−1 [20].co3 content was calculated from the absorbanceratio of co3 band at 1,410 cm−1 to po4 band at 575 cm−1based on a method described by featherstone et al. [20]. fig. 3. ftir spectra of mixed size sample of phosphate ore(before acid leaching). all bandsobserved in the ftir of fig. 4 are associated with theinorganic components of apatite which were present in thephosphate ore. these bands can be divided into three maincategories associated with phosphate, carbonate and hydroxyl groups. one strong and relatively broad bandat 1033 cm−1, two relatively strong and sharp bands at569 cm−1 and 603 cm−1 and another band at 966 cm−1which appear on the ftir spectrum of are dueto the phosphate group. the bands whichappear at 873 cm−1, 1417 cm−1 and 1456 cm−1 are associatedwith the carbonate group. 8. results and discussion 8.1. sieving from the sieving results of the apatite ore shown in table 2, it was found that phosphate (p2o5) content iscommonly concentrate in the fractions range (150-300 nm), while decrease out of this range, i.e. in the particle size larger than 300 nm and smaller than 150 nm as shown in figure4.this behaviorcan be explained due to the difference in hardness between apatite and calcite (main constituent), leading the powder to contain coarse apatite particles and fine calcite particles during crushing of ore. fig. 4. effect of particle size on phosphate contentin the phosphate ore. 8.2. acid leaching leaching of apatite using acetic acid achieved according to the conditions summarized in table (1). after each run the extracted ore filtered by buchner funnel, and dried at 105 oc for two hours and then analyzed using x-ray diffraction. figures 5, 6 show the xrd of the best run using acetic acid leaching and the best run using lactic acid leaching respectively. fig. 5. x-ray diffraction of the best run using acetic acid leaching. c.kh. haweel al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 2438 (2013) 32 fig. 5. x-ray diffraction of the best run using lcetic acid leaching. the calcite and apatite relative intensity ratios (rir%) obtained from the experiments are fixed in table (3) columns (5,6) respectively. a regression analysis applied to get the polynomial of equation (15) using statistica ® kernel release 6.0. this equation represents the best mathematical form that relates apatite content as a relative intensity ratio (rir %), with the three studied variables, acid concentration (wt.%), liquid to solid ratio (ml/gm) and reaction time (min.). value of correlation coefficient was 0.9041. ap. rir% = 91.01890 − 0.538442 ∗ c0.313744 ∗ r − 0.087618 ∗ t − 0.015311 ∗ c ∗ r0.010784 ∗ c ∗ t + 0.008245 ∗ c + 0.019954 ∗r …(15) where: ap. rir%= percentage of relative intensity ratio of apatite content c= acid concentration (wt. %) r= acid volume to ore weight ratio (ml/gm) t= reaction time (min.) the same procedure repeated using lactic acid leaching and the results shown in table (4). again a regression analysis applied using the same procedure to get a mathematical polynomial as shown in equation (16) express the variables affecting leaching using lactic acid with correlation coefficient was 0.9372. ap. rir% = −10.9799 + 15.86836 ∗ c +6.364276 ∗ r + 1.012614 ∗ t − 0.807941 ∗ c ∗r − 0.120940 ∗ c ∗ t − 0.082444 ∗ r ∗ t +0.009692 ∗ c ∗ r ∗ t − 0.447970 ∗ c^2 …(16) parameters of equation (16) are the same as in equation (15). these mathematical forms are used to plot graphical figures relating apatite content versus each corresponding variable (acid concentration, acid to ore ratio and reaction time), to evaluate the optimum operating conditions which give the best phosphate concentration resulting from the leaching process. table 3, intensities of ore main components obtained by x-ray diffraction of the acetic acid leaching. exp. no. calcite intensity apatite intensity total intensity calcite rir% apatite rir% 1 110 614 724 15.19 84.80 2 148 828 976 15.16 84.83 3 142 806 948 14.97 85.02 4 156 782 938 16.63 83.36 5 108 604 712 15.16 84.83 6 104 632 736 14.13 85.86 7 144 802 946 15.22 84.77 8 126 820 946 13.31 86.68 9 152 860 1012 15.01 84.98 10 108 624 732 14.75 85.23 11 150 792 942 15.92 84.07 12 110 634 744 14.78 85.21 13 146 874 1020 14.31 85.68 14 130 796 926 14.03 85.96 15 148 824 972 15.22 84.77 c.kh. haweel al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 2438 (2013) 33 table 4, intensities of ore main components obtained by x-ray diffraction of the lactic acid leaching. exp. no. calcite intensity apatite intensity total intensity calcite rir% apatite rir% 1 276 1490 1766 15.62 84.37 2 272 1550 1822 14.92 85.07 3 246 1576 1822 13.50 86.49 4 270 1474 1744 15.48 84.51 5 300 1550 1850 16.21 83.78 6 274 1596 1870 14.65 85.34 7 272 1588 1860 14.62 85.37 8 556 1456 2012 27.63 72.36 9 276 1626 1902 14.51 85.48 10 264 1594 1858 14.20 85.79 11 268 1630 1898 14.12 85.87 12 646 1528 2174 29.71 70.28 13 292 1580 1872 15.59 84.40 14 284 1676 1960 14.4 85.5 15 310 1638 1948 15.91 84.08 8.3. effect of acid concentration the effect of acid concentration (wt.%) on the apatite content in the ore, using acetic acid leaching is shown in fig.7. this figure shows the relation between acetic acid concentration (in weight percent), and apatite content expressed as relative intensity ratio based on x-ray diffraction of the beneficiated samples at different ratios of acid volume to ore weight in a range of (5-13 ml/gm) at a constant reaction time of 10 min. fig. 7. effect of acetic acid concentration on apatite content at various ratios of acid volume to ore weight. it is clearly found that increasing the acid concentration leads to a decrease in the apatite content. the explanation of this case is, at low concentrations of acetic acid, there is a desirable reaction with calcite (reaction3, page 3). increasing the acid concentration decreases the selectivity of acetic acid reaction leading to an undesirable reaction with the required material (apatite) in the ore as shown in the reaction 4 (page4) [10]. malash[12], showed that at lower acetic acid concentrations, there is a greater probability of the reaction between calcium carbonate and the acetic acid with a result of an increase of the p2o5 grade in the treated rock. then as the concentration of the acetic acid increase there is a corresponding increase in the polarity of the oh group, the acid will react with the calcium carbonate to a lesser extent and hence more calcium carbonate will remain with the solid residue remaining after the experiment, and therefore the p2o5 grade in the treated rock will decrease again. the effect of ratio of acid volume to ore weight is less than that of acid concentration. generally at low concentration the high ratio (l/s=13) gives more efficient beneficiation than that of low ratio (l/s=5). when lactic acid used as a leaching agent to concentrate phosphate it gives a different behavior compared with acetic acid as shown in fig. (8). c.kh. haweel al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 2438 (2013) 34 fig. 8. effect of lactic acid concentration on apatite content at various ratios of acid volume to ore weight. this figure shows the relation between lactic acid concentration and apatite content expressed as relative intensity ratio as in figure 10, at differentratios of acid volume to ore weight in a range of (5-15 ml/gm) and a constant reaction time of 10 min. this figure shows that at low ratios of acid volume to ore weight, increasing the acid concentration leads to a distinct increase in the apatite content. it means that apatite content is related to the stoichiometry amount of acid necessary to react with calcium carbonate. when this amount exceeds the stoichiometry limits, reaction selectivity decreased as the acid start the undesired reaction with apatite. gharabaghi et al [14], stated that the acid concentrationthat gives the best leaching result has been found to depend on acidtype, carbonates mineral content and the liquid/solid ratio. 8.4. effect of acid volume to ore weight figure (9) shows the effect of ratio of acid volume to ore weight at different concentrations of acetic acid and a fixed leaching time of 10 minutes. it was found that increasing the ratio at high acid concentrations decreases the apatite content. fig. 9. effect of ratio of acetic acid volume to ore weight on apatite content at various acid concentrations. malash [12], explained that at high acid concentrations when the quantity of acid increases, it leads to more phosphate loses because a greater chance of the reaction of the acid with tricalcium phosphate found in the phosphate rock. this happens because the reaction of acetic acid with phosphate rock begins at the surface particles, and as the quantity of the acid increases it begins to penetrate to the inner layers leading to increased attack and hence more p2o5 loses. leaching with lactic acid shows different behavior from that of acetic acid in the case of acid to ore ratio as shown in figure (10). increasing that ratio at low acid concentration leads to an increase in the apatite content. while at highlactic acid concentrations it gives undesired result by reducing the apatite content. this explains the selective reaction of lactic acid with calcium carbonate at low concentrations of acid, related to the stoichiometry amount of acid sufficient to digest the calcite, while this selectivity decreased when acid concentrations increased above 8 weight percent (i.e. at higher concentration the acid begin an undesired reaction with apatite). c.kh. haweel al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 2438 (2013) 35 fig. 10. effect of ratio of lactic acid volume to ore weight on apatite content at various acid concentrations. from the mentioned figures it can be noticed that the optimum conditions of acid concentration and volume of acidto ore weight ratio for acetic acid are (2wt%) and (13ml/gm) respectively. for lactic acid these conditions are (10wt%) and (5ml/gm) respectively. 8.5. effect of reaction time in all of the experiments, ph data was recorded versus reaction time. because the reaction is taken place between the acid and ore, hydrogen ion concentration must be decrease with time and this decrease considered as an indication to the reaction continuity. figure 11 shows ph data vs. time for acetic acid leaching. it was noted that the reaction is fast through the first 3 minutes, and then its speed decreased until reach 10 minutes. after this limit, the reactants ph be stable in most of the experiments (3-15) and in experiments 1 and 2 it be constant when reach time of 20 minutes. fig. 11. ph values vs. reaction time with acetic acid of all experiments according to conditions in table (1). variation of ph data with time using lactic acid is similar to that of acetic acid as shown in figure 12.this means that the optimum reaction time can be taken 10 minutes. figures 13 and 14 demonstrate variation of apatite content with reaction time at different acid concentrations. fig. 12. ph values vs. reaction time with lactic acid of all experiments according to conditions in table (1). c.kh. haweel al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 2438 (2013) 36 fig. 13. change in apatite content with reaction time using acetic acid. fig. 14. change in apatite content with reaction time using lactic acid. it can be deduced from fig. 13 that more than 90 percent of the apatite recovery occurs in the first ten minutes, and the change in acid concentration leads toa small effect on the behavior of the acid. the recovery of apatite using lactic acid is more influenced by acid concentration as shown in fig. 14. at low acid concentrations apatite content increased slowly and more time required reaching the desired recovery. while at high acid concentrations most of the apatite recovered in the first 20 minutes. 8.6. ftir analysis figure 15 explains the ftir spectraof the treated sample of apatite ore using lactic acid at the optimum conditions of (10wt%), (5ml/gm) and (10min.). in the obtained spectra, po4 absorptionbands were observed at 1,000–1,100 cm−1 and 550–600cm−1, which were assigned to po4 3− ion in the apatitelattice as noticed in fig. 3. absorption band at 1,400–1,500 cm−1 wasassigned to co3 2− ion in the apatite lattice. it is deduced that after acid leaching, the absorbency of carbonate band co3 at 1400-1500 cm-1 was decreased to values smaller than the absorbency bands of apatite at 575 and 1100 cm-1, this ensure that a selective reaction occurred by the acid with calcite and enhance the apatite concentration in the extracted ore. fig. 15. ftir spectra of the treated phosphate ore using lactic acid at the optimum conditions. 9. conclusions 1from the established work, it is concluded that beneficiation of akashat phosphate ore to improve apatite content using leaching with organic acids (acetic acid and lactic acid) was characterized by high efficiency, low cost, simple operating conditions (room temperature and atmospheric pressure), possibility to recover the organic acid, keeping the surface properties of the produced phosphate. in addition, it does not cause particular environmentalhazardsthrough the ability to produce pure calcium sulfate (gypsum). 2using the two acids (acetic acid and lactic acid) yields closed purity values of apatite at the optimum conditions. when comparing the produced apatite purity at different acid concentrations, it was found that the efficiency of acetic acid is higher at the low concentration (2wt.%), while lactic acid gives the higher efficiency at high concentration (10wt.%). c.kh. haweel al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 2438 (2013) 37 3with respect to the ratio of acid volume to ore weight ratio it was found that increasing this ratio to (13ml/gm)cause an increase in the purity of apatite at the optimum concentration for acetic acid. while for lactic acid this ratio found to be optimum at (5ml/gm) when the acid concentration be (10wt%). 4it was found that the reaction of organic acids with the calcareous material is fast and that the apatite purity increased to the best resultat reaction time of 10minutes. 10. references [1] al-fariss, t.f., ozbelge, h.o. and el-shall, h.s., “on the phosphate rock beneficiation for the production of phosphoric acid in saudi arabia”, journal king saud university engineering science, 4 (l), 13–32, 1992. [2] guimarães, r.c., araujo, a.c. and peres, a.e.c.,“reagents in igneous phosphate ores flotation”, minerals engineering, 18, 199– 204, 2005. [3] elliott, j.c., structure and chemistry of the apatites and other calcium orthophosphates, elsevier: amsterdam, 1994. [4] abouzeid, a.z.m.,”physical and thermal treatment of phosphate ores—an overview”, international journal of mineral processing 85, 59–84, 2008. [5] shirqi, i.s. andtawfiq, o.a., “akashat phosphate mine”, report of the ministry of industry and minerals, iraqi state company for phosphate, feb. 2010. [6] leder, f., park, w.c., chang, p.w., ellis, j.d., megy, j.a., hard, r.a.,kyle, h.e., mu, j. and shaw, b.w.,ind. eng. chem. process des. dev., 24, 688, 1985. [7] van der sluis, s., “a cleantechnology phosphoric acid process”, ph.d. thesis, delft university press, 1987. [8] rao, t.c., rao, l.s., rao, g.m., “beneficiation of indian low grade phosphate deposits: problems and prospects”, transactions of the indian institute of metals 45 (3), 195–205, 1992. [9] gharabaghi, m., noaparast, m. andirannajad, m., “selective leaching kinetics of lowgrade calcareous phosphate ore in acetic acid”, hydrometallurgy 95, 341–345, 2009. [10] heidarpour, t., “processing of dalir phosphate samples using leaching method”,m.sc thesis, department of mining & metallurgical engineering, amirkabir university of technology, iran, 2009. [11] malash, g.f., “beneficiation of abu tartur phosphate rock by leaching with dilute acetic acid solution”, alexandria engineering journal 44 (2), 339–345, 2005. [12] al-fariss, r.f., “beneficiation of carbonate rich saudi phosphate rocks”, in: el-shall, h., moudgil, b.m.,wiegel, r. (eds.), beneficiation of phosphate: theory and practice.sme,littleton, pp. 251–259, 1993. [13] m. gharabaghi, m. irannajad and m. noaparast, “a review of the beneficiation of calcareous phosphate ores using organic acid leaching”, hydrometallurgy, 103, 96– 107,2010. [14] sengul, h., ozer, a.k. and gulaboglu, m.s.,“beneficiation of mardin–mazidagi (turkey) calcareous phosphate rock using dilute acetic acid solutions”, chemical engineering 122, 135–140, 2006. [15] zafar, z.i. and ashraf, m., “selective leaching kinetics of calcareous phosphate rock inlactic acid”, chemical engineering journal,131, 41–48,2007. [16] jeppson, l., fredholm, d. andmattiasson, b.o., “acetic acid and phosphatic fossils; a warning”, journal of paleontology, 59 (4), 952–956,1985. [17] bali, u., “application of box–wilson experimental design method for the photodegradation of textile dyestuff with uv/h2o2 process”, dyes and pigments, 60, 187–195,2004. [18] bergslien,e.t., et al., “identification of cremains using x-ray diffraction spectroscopy and a comparison to trace element analysis”, forensic science international, 175, 218–226, 2008. [19] apfelbaum f., diab h., mayer i. and featherstone jdb.,“an ftir study of carbonate in synthetic apatites”, j.inorg.biochem., 45, 277-282,1992. [20] featherstone, jdb., pearson, s., legeros, rz.,“an infrared method for quantification of carbonate in carbonated apatites”, caries res, 18, 63-66,1984. )2013( 2438، صفحة 4، العدد9مجلة الخوارزمي الھندسیة المجلد سیسیلیا خوشابا ھاویل 38 عكاشات العراقیة باستخدام الحوامض العضویة لغرض انتاج حامض تنقیة خام فوسفات الفسفوریك بالطریقة الرطبة ***ىمحمد یعقوب عیس **عبد المجیدبسمة عباس *لویھاسیسیلیا خوشابا جامعة بغداد/ كلیة الھندسة / قسم الھندسة الكیمیاویة ***،**،* cicil@yahoo.com : االلكتروني البرید* basma1957@yahoo.com : االلكتروني البرید** mohammedyeisa@yahoo.com : اللكترونيا البرید*** الخالصة لغرض استخالص مادة االبتایت من ) حامض الخلیك وحامض الالكتیك(البحث الحالي یتضمن دراسة لعملیة االستخالص باستخدام الحوامض العضویة ).بشكل رئیسي مادة الكلس(خام الفوسفات العراقیة المستخرجة من منطقة عكاشات وذلك بفصل المركبات الكلسیة كبریتات ھذه الطریقة بعدة مزایا، منھا التقلیل من كمیة الطاقة المصروفة، التقلیل من الملوثات البیئیة من خالل استرجاع مادة الكلس على شكل تتمیز لتقلیل من كمیة الماء بدال عن طرحھا الى التربة كناتج عرضي، الحفاظ على الخواص الفیزیائیة والكیمیائیة لمادة االبتایت المفصولة وا) الجبس(الكالسیوم .ftir، والمطیافیة الضوئیة لالشعة تحت الحمراء x-ray diffractionتم تحلیل العینات بالحالة الصلبة باستخدام طریقة الحیود باالشعة السینیة.المستھلك االبتایت بنقاوة متقاربة، بینما عند استخدام من خالل بیانات النتائج العملیة وجد بأن استخدام الحامضین العضویین عند الظروف المثلى ینتج مادة ھي االعلى الحامضین بتراكیز مختلفة وجد بان كفاءة عملیة الفصل بحامض الخلیك ھي االعلى عند التراكیز المنخفضة وان كفاءة الفصل بحامض الالكتیك غم یؤدي الى زیادة في نقاوة مادة االبتایت /مل ٥لیل ھذه النسبة الى بخصوص نسبة حجم الحامض المستخدم الى وزن الخام وجد بأن تق. عند التراكیز العالیة باالضافة الى ذلك، وجد بأن تفاعل الحامضین العضویین مع المواد الكاربونیة سریع وان افضل زمن للتفاعل . المنتجة وذلك عند التراكیز المثلى للحامضین .دقیقة ١٠النتاج االبتایت بنقاوة عالیة ھو عند mailto:cicil@yahoo.com mailto:basma1957@yahoo.com mailto:mohammedyeisa@yahoo.com كاظم مطر47-39 al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 7, no. 3, pp 39 47 (2011) coagulation-flocculation process to treat pulp and paper mill wastewater by fenugreek mucilage coupled with alum and polyaluminum chloride kadhum m. shabe suhama e. salah mervit m. janbi department of material engineering/ university of technology (received 29 march 2011; accepted 30 jun 2011) abstract the wastewater arising from pulp and paper mills is highly polluted and has to be treated before discharged into rivers. coagulation-flocculation process using natural polymers has grown rapidly in wastewater treatment. in this work, the performance of alum and polyaluminum chloride (pacl) when used alone and when coupled with fenugreek mucilage on the treatment of pulp and paper mill wastewater were studied. the experiments were carried out in jar tests with alum, pacl and fenugreek mucilage dosages range of 50-2000 mg/l, rapid mixing at 200 rpm for 2 min, followed by slow mixing at 40 rpm for 15 min and settling time of 30 min. the effectiveness of fenugreek mucilage was measured by the reduction of turbidity and chemical oxygen demand (cod). the results show that the combination of pacl and fenugreek mucilage is more effective than alum, pacl and alum + fenugreek mucilage. it can achieve greater than 97% of turbidity reduction and greater than 98% of cod reduction at low dosage of pacl (50 mg/l) and fenugreek mucilage (100 mg/l). the results indicate that lower quantities of pacl are needed to obtain an acceptable reduction in turbidity and cod in the treatment of pulp and paper mill wastewater. keywords: pulp and paper mill wastewater, coagulation and flocculation, fenugreek. 1. introduction wastewater from pulp and paper mills constitutes a major source of aquatic pollution since it contains high organic substances causing high biochemical oxygen demand (bod) and chemical oxygen demand (cod), extractives (resinacids), chlorinated organics (measured as adsorbable organic halides, aox), suspended solids, metals, fatty acids, tannins, lignin and its derivatives (ali and sreekrishnan, 2001; lacorte et al., 2003). pulp and paper mill wastewater is little biodegradable, with bod/cod ratio values usually around 0.02-0.07 [14]. morais et al. (2006) report that samples with biodegradability index smaller than 0.3 are not appropriate for biological degradation. according to chamarro et al. (2001) for complete biodegradation, the effluent must present a biodegradability index of at least 0.40. consequently, a new approach in the wastewater treatment technology should be developed to face more stringent environmental regulations on the quality of the effluents entering receiving waters. flocculation is one of the important treatments given to the industrial e uent before discharging them into rivers to remove toxic waste. recently, the use of synthetic polyelectrolytes as flocculants for suspended solids removal in wastewater treatment has grown rapidly [13]. the advantage of polymeric flocculants is their ability to produce large, dense, compact and stronger flocs with good settling characteristic compared to those obtained by coagulation. it can also reduce the sludge volume. furthermore, the polymer performance is less dependent on ph. natural polymers such as starch, sodium alginate, amylopectin, guar gum, xanthum gum, kendu gum and chitosan [12, 15, 6, 5], find extensive application as flocculants. recently, the use of fenugreek mucilage, a food grade natural polysaccharide, has been reported as a flocculant for tannery effluent treatment [11]. kadhum m. shabe al-khwarizmi engineering journal, vol. 7, no. 3, pp 39 47 (2011) 40 in the present study, coagulation-flocculation by alum and pac when coupled with fenugreek mucilage is applied to pulp and paper mill industry effluents. the effects of coagulant dosage, flocculant dosage and ph are studied. the turbidity and cod values are used as evaluating parameters. 2. experimental work 2.1. wastewater the wastewater samples used in this study were obtained from pascorp paper sdn. bhd. which is situated in bentong, pahang, malaysia. the samples were taken after the physical treatment plant facility. wastewater samples were characterized and the analyses are given in table 1. these parameters were measured based on the standard methods for the examination of water and wastewater [2]. 2.2. chemicals polyaluminium chloride (pacl): pacl is a synthetic polymer, which is yellow in color. this chemical is used as a coagulant in this research. the pacl used in this research was manufactured by r&m chemicals marketing, essex, u.k. aluminium sulphate (alum): alumium sulphate, or alum is an inorganic coagulant, in a molecular form. the alum used in this research was manufactured by r&m chemicals marketing. fenugreek mucilage: fenugreek mucilage, an amorphous natural poly-saccharide is composed of d-galactose and d-mannose in 1:1 ratio and 1:1.2 ratio. extraction of the milled seeds with cold water yielded a thick mucilaginous solution. this material is used as flocculant aid in this research. it is added during the slow mixing period in jar test experiments. to prepare fenugreek mucilage, 50 g of fenugreek seeds were dissolved in 1 l of distilled water. this solution was then stirred for 24 hours. the homogenous solution was then centrifuged to purify fenugreek mucilage. 2.3. experimental procedures jar test procedures were performed with the conventional jar apparatus (stuart science flocculator model, swi) using (1l) wastewater. different combinations of ph (3, 6, 9), alum and pac dosages (50, 100, 500, 1000, 1500, 2000 mg/l) and table 1, chemical characteristics of wastewater samples. parameter ph turbidity (ntu) cod (mg l1) bod (mg l1) value 6.80 235.00 20300.00 636.00 fenugreek muciluge dosage (50, 100, 500, 1000, 1500 and 2000 mg/l) were tested. the selected coagulant dosage was added to 1 l of wastewater and it was stirred for a period of 2 min at 200 rpm. it was followed by a further slow mixing of 15 min at 40 rpm after the selected fenugreek dosage was added to the same solution. the ph of the solution was adjusted accordingly. the flocs formed were allowed to settle for 30 min. after settling, the turbidity and cod of the supernatant were determined. all parameters were determined according to the apha method. 2.4. analytical methods turbidity was measured by a turbid meter manufactured by eutech (model 2100a). turbidity was measured by putting 10 ml of sample into turbidity vial and place it in turbidity meter to measure turbidity. cod was determined by potassium dichromate method by adding 2 ml of treated wastewater into cod digestion reagent. then, the vial was capped tightly and inverted several times to mix. after that, the vial was placed in the preheated cod digestion reactor and heated for two hours. then, the cod reactor was switched off and the vial was left to cool to room temperature. finally, cod was measured by spectrophotometer, hatch dr/2400. the above-mentioned parameters were measured according to the standard method for the examination of water and wastewater. 3. results and discussion 3.1. treatment by alum coagulant dosage and ph play an important role in determining the optimum conditions of coagulation flocculation process. in wastewater treatment using inorganic coagulants, an optimum ph range in which metal hydroxide precipitates occur, should be determined. the effects of ph adjustment and coagulant dosage by alum on kadhum m. shabe al-khwarizmi engineering journal, vol. 7, no. 3, pp 39 47 (2011) 41 turbidity and cod are illustrated in figures 1 and 2, respectively. figures 1 and 2 show that turbidity and cod reduction efficiencies increase with the increase in coagulant dosage till it reaches its highest value after which the reduction and removal efficiencies start to decrease. it can be seen that the optimum dosage is approximately 1000 mg/l and the optimum ph is approximately 6.0. at these optimum dosage and ph, turbidity reduction is 91.28% and cod reduction is 95% followed by a further slow mixing of 15 min at 40 rpm after the selected fenugreek dosage was added to the same solution. the ph of the solution was adjusted accordingly. the flocs formed were allowed to settle for 30 min. after settling, the turbidity and cod of the supernatant were determined. all parameters were determined according to the apha method. fig.1. effect of alum dose on percent removal of turbidity at different ph. fig.2 effect of alum dose on percent removal of cod at different ph. 3.2. treatment by pacl to study the effects of the pacl dosage and ph on the turbidity reduction and cod reduction, jar tests were conducted with the pacl dosages of 50, 100, 500, 1000, 1500 and 1500 mg/l and ph adjusted to 3, 6 and 9. the results obtained are shown in fig. 3 and 4. the effects of coagulant dosage and ph with pacl are parallel to the effects observed with alum. the turbidity reduction and cod reduction efficiencies increase with the increase in coagulant dosage and ph till it reaches its highest value after which the reduction and removal efficiencies start to kadhum m. shabe al-khwarizmi engineering journal, vol. 7, no. 3, pp 39 47 (2011) 42 decrease. as shown in fig.3, the turbidity reduction efficiency at ph 6 is higher than that at ph 3 and 9 at low dosage. the highest turbidity reduction is 95.66%. figure 4 shows that the pacl dosage only reveals minor impacts on the reduction efficiencies of cod at ph 9. nevertheless, ph shows significant effects on the cod reduction at ph 3 and 6. the cod reduction efficiency reaches to more than 95% at pacl dosage and ph 500 mg/l and 6.0, respectively. this result reveals that the optimum coagulant dosage for pacl is less than that of alum but the optimum ph for both coagulants remains the same at ph 6.0. fig.3. effect of pacl dose on percent removal of turbidity at different ph. fig.4. effect of pacl dose on percent removal of cod at different ph. according to huang and pan (2002), at lower ph and lower coagulant dosage, the only mechanism for the destabilization of particles is charge neutralization. at low ph and because the aggregates are small in size, the mechanism of colloidal destabilization is mainly charge neutralization. at lower dosage, pacl behaves like the alum salt; therefore, charge neutralization is the principal mechanism for destabilization. as stated by huang and pan (2002), pacl is a prehydrolyzed inorganic coagulant. it is prepared by reacting naoh or na2co3 with concentrated alcl3 solution under controlled reaction rate and mild temperature. the extent of prehydrolysis of kadhum m. shabe al-khwarizmi engineering journal, vol. 7, no. 3, pp 39 47 (2011) 43 pure pacl is described in terms of the ligand ratio r, which is the molar ratio of hydroxide (oh-) to the total al present in solution (altotal). theoretically, r is in the range between 0 and 3, or basicity between 0 and 100%. basicity is the percentage of al3+ acidity satisfied by prehydrolysis or base addition. the major dissolved al species from pacl available for coagulation is controlled by r. for r < 1 (basicity <33%), monomeric al species such as al3+ and aloh2+ dominate. some dimeric al such as al2(oh)2 4+ may be present. the basicity of the pacl used in the present study is 30%. evidently, this indicates that the main al species present for the destabilization of colloidal particles are monomeric and dimeric al which functions only through charge neutralization. 3.3. treatment by alum with fenugreek mucilage alum is used in coupled with fenugreek mucilage to improve the performance of flocculation process. fenugreek mucilage acts as a flocculent aid which provides more collision opportunity among suspended particles in the wastewater and the inorganic coagulants. this in turn would increase successful collision rate, hence forming larger and denser flocs. the effect of polysaccharide flocculant dosages on the reduction of turbidity andcod was investigated. flocculant dosage was increased from 50-2000 mg/l with a fixed amount of alum (100 mg/l). the initial ph of wastewater was adjusted to ph 6.0. the reduction or removal of turbidity and cod efficiencies were calculated from the turbidity and cod initial concentration in the raw wastewater and final concentration in the supernatant. the results obtained for alum plus fenugreek treatment is depicted in figs. 5 and 6. the reduction and removal efficiencies of turbidity did not change significantly. on the other hand, the cod reduction efficiency increased appreciably as shown in fig. 6. the positive effect of using fenugreek mucilage could be clearly observed for low coagulant dosages of 50, 100 and 500 mg/l since a much greater reduction efficiency in cod is achieved when only the alum is used. the reduction efficiency of cod is improved from 55-95% for alum and fenugreek mucilage dosage of 100 and 1000 mg/l respectively. this means that lower quantities of alum are needed to obtain an acceptable reduction in cod. fig.5. comparison of % turbidity removal with and without addition of fenugreek mucilage to alum. kadhum m. shabe al-khwarizmi engineering journal, vol. 7, no. 3, pp 39 47 (2011) 44 fig.6. comparison of % cod removal with and without addition of fenugreek mucilage to alum. 3.4. treatment by pacl with fenugreek mucilage pacl is used with fenugreek mucilage to improve the performance of flocculation process. flocculant dosage was increased from 50-2000 mg/l with a fixed amount of pacl (50 mg/l). the initial ph of wastewater was adjusted to ph 6.0. figures 7 and 8 show the plots of percent reduction of turbidity and cod vs. polysaccharide dose. it is apparent that the performance of pacl plus fenugreek mucilage in terms of turbidity reduction is the best combination coagulant + flocculant system in comparison with fenugreek alum combination.the effect of flocculant addition on turbidity removal is depicted in fig.7 which shows a similar performance over the entire range of polysaccharide dose. this combination system achieves more than 97% removal of turbidity when fenugreek mucilage dosage is greater than 100 mg/l. this means that lower quantities of pacl and fenugreek mucilage are needed to obtain high reduction in turbidity. this behavior could be explained by the fact that optimal dose of flocculant in suspension causes larger amount of suspended solids to aggregate and settle thus decreasing the total solids in the effluent. fig.7. comparison of % turbidity removal with and without addition of fenugreek mucilage to pacl. kadhum m. shabe al-khwarizmi engineering journal, vol. 7, no. 3, pp 39 47 (2011) 45 fig.8. comparison of % cod removal with and without addition of fenugreek mucilage to pacl. figure 8 shows the effect of fenugreek mucilage addition on the reduction efficiency of cod. the results show that the cod reduction is improved over the entire range of fenugreek mucilage. the addition of flocculant exhibit very high cod reduction efficiency (>98%) even at low dosage of pacl and fenugreek mucilage. this indicates that the use of flocculant lowers the coagulant dosage needed to obtain a satisfactory reduction in cod. obviously, the pacl performs much better than alum in the reduction efficiency of turbidity and cod. these results suggested that the use of fenugreek mucilage will reduce the usage of pacl coagulant. 4. conclusion reduction of turbidity and cod were studied using alum+fenugreek mucilage and pacl+fenugreek mucilage as a combination system for treating pulp and paper mill wastewaters. the results were compared with conventional coagulants like alum and pac. the results show that the combination of pacl and fenugreek mucilage is more effective than alum, pacl and alum+fenugreek mucilage. it can achieve greater than 97% of turbidity reduction and greater than 98% of cod reduction at low dosage of pacl (50 mg/l) and fenugreek mucilage (100 mg/l). obviously, the combination of fenugreek mucilage with pacl performs much better than that with alum in the reduction efficiency of turbidity and cod. these results suggested that the use of fenugreek mucilage will reduce the usage of pacl coagulant. 5. reference 6. [1] ali, m. and t.r. sreekrishnan, "aquatic toxicity from pulp and paper mill effluents" a review. adv. environ. res., 2001, 5: 175196. [2] apha, 1998." standard methods for the examination of water and wastewater", 20th edn., american public health association, washington. [3] chamarro, e., a.marco and s. esplugas, " use of fenton reagent to improve organic chemical biodegradability" water res., 2001,35: 1047-1051. [4] davis, t.a., b. volesky and r.h.s.f. vieira, "sargassum seaweed as biosorbent for heavy metals" water res., 2000, 34: 42704278. [5] davis, t.a., b. volesky and r.h.s.f. vieira, "sargassum seaweed as biosorbent for heavy metals" water res., 2000, 34: 42704278. [6] divakaran, r. and v.n.p. sivasankara, "flocculation of kaolinite suspensions in water by chitosan" water res., 2001,35: 3904-3908. [7] ebeling, j.m., k.l. rishel and p.l. sibrell, "screening and evaluation of polymers as kadhum m. shabe al-khwarizmi engineering journal, vol. 7, no. 3, pp 39 47 (2011) 46 flocculation aids for the treatment of aquacultural effluents". aquacult. eng., 2005, 33: 235-249. [8] huang, c. and j.r. pan,."coagulation approach to water treatment", encyclopedia of surface and colloid science, 2nd edition, marcel dekker inc., new york. ,2002, 5667 [9] lacorte s., a. latorre, d. barceló, a. rigol, a. malmqvist and t. welander,. "organic compounds in paper-mill process waters and effluents", trac trends in analytical chemistry, 2003, 22:725-737. [10] mishra, a., a. yadav, m. agarwal and m. bajpai, "fenugreek mucilage for solid removal from tannery effluent ",reactive functional polymers, 2003,59: 99-104. [11] morais, j.l., c. sirtori and p.g. peraltazamora, quım. nova, 2006,29: 20-23. [12] samantaroy, s., a.k. mohanty and m. misra, j. applied polymer sci.,1997,66: 1585. [13] sarika, r., n. kalogerakis and d. mantzavinos, "treatment of olive mill effluents part ii. complete removal of solids by direct flocculation with polyelectrolytes" environ. int., 2005,31: 297304. [14] thompson, g., j. swain, m. kay and c.f. forsterbioresour. technol., 2001, 77: 275286. [15] udaybhaskar, p., l. iyengar and r.a.v.s. prabhakar, , j. applied polymer sci., , 2001 , 39: 739. )2011( 39 47 ، صفحة3، العدد 7د مجلة الخوارزمي الھندسیة المجل كاظم مطر شبیب 47 في معالجة دراسة أداء كل من الشب والبولي ألمنیوم كلوراید مع دبق الحلبة الناجمة عن معامل الورقمخلفات المیاه میرفت مھدي حنوص كاظم مطر شبیب سھامة عیسى صالح الجامعة التكنولوجیة/ فسم ھندسة المواد الخالصة بر عملیة التخثیر وتعت. تعتبر مخلفات المیاه الناجمة عن معامل الورق من المیاه الملوثة بدرجھ كبیره مما یتطلب معالجتھا قبل تصریفھا إلى األنھار كل من الشب والبولي المنیوم في ھذا البحث تم دراسة أداء. والتلبید باستخدام البولیمرات الطبیعیة من الطرق التي تزاید استخدامھا في معالجة مخلفات المیاه وقد أجریت التجارب باستخدام . كلوراید كل على حده و الشب والبولي المنیوم كلوراید مع دبق الحلبھ في معالجة مخلفات المیاه الناجمة عن معامل الورق دوره في الدقیقھ لمدة ٢٠٠لتر ومزج سریع مقداره /مملغ ٢٠٠٠-٥٠اختبار الجره وبجرع مختلفة للشب والبولي المنیوم كلوراید ودبق الحلبة تتراوح بین وقد قیست فعالیة دبق الحلبة اعتمادا على االنخفاض في . دقیقھ ٣٠دقیقھ وزمن تركید مقداره ١٥دوره في الدقیقة لمدة ٤٠دقیقتین متبوع بمزج بطئ مقداره بق الحلبھ مع البولي المنیوم كلوراید یكون أكثر فعالیة من استخدام الشب والبولي وقد أظھرت النتائج ان استخدام د. العكوره ومتطلب األوكسجین الكیمیاوي ونسبة االنخفاض في متطلب % ٩٧حیث بلغت نسبة االنخفاض في العكوره اكثر من . المنیوم كلوراید من دون إضافة دبق الحلبة والشب مع دبق الحلبھ ان النتائج المستحصلھ تدل على ). لتر/ملغم ١٠٠(ودبق الحلبھ ) لتر/ملغم ٥٠(ولي المنیوم كلوراید وبجرعھ واطئھ للب% ٩٨األوكسجین الكیمیاوي أكثر من لمیاه الناجمة عن امكانیة استخدام كمیات قلیلھ من البولي المنیوم كلوراید للحصول على انخفاض مقبول في العكوره ومتطلب االوكسجین الكیمیاوي لمخلفات ا .معامل الورق حيدر عبد ضهد77-68 al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 7, no. 3, pp 68 77 (2011) charge stratification and fuel/air ratio effect on the efficiency of (icade) i. c. engine cycle hayder abed dhahad center of training and workshops/ university of technology email: hayder_abed2002@yahoo.com (received 18 july 2009; accepted 2 jun 2011) abstract the isolated combustion and diluted expansion (icade) internal combustion engine cycle combines the advantages of constant volume combustion of the otto cycle with the high compression ratio of the diesel cycle. this work studies the effect of isolated air mass (charge stratification) on the efficiency of the cycle; the analysis shows that the decrease of isolated air mass will increase the efficiency of the cycle and the large dilution air mass will quench all nox forming reactions and reduce unburned hydrocarbons. furthermore, the effect of fuel / air ratio on the efficiency shows that the increase of fuel / air ratio will increase efficiency of the cycle. keywords: i.c. engine cycle, isolated combustion, diluted expansion, cycle efficiency. 1. introduction the study of air standard cycles to obtain the performance of internal combustion engine has a great importance in spite of the actual engine works at different conditions rather than the supposed conditions in air standard cycles [11]. the actual cycle experienced by an internal combustion engine is not, in the true sense a thermodynamic cycle. an ideal air-standard thermodynamic cycle occurs in a closed system of constant composition. this is not what actually happens in an ic engine, and for this reason airstandard analysis gives, at best, only approximations to actual condition and outputs. major differences include: [1] 1. real engines operate on an open cycle with changing composition. not only does the inlet gas composition differ from what exit, but often the mass flow rate is not the same. during combustion, total mass remains about the same but molar quantity changes. finally, there is a loss of mass during the cycle due to crevice flow and blow by past the pistons. 2. air-standard analysis treats the fluid flow through the entire engine as air and approximates air as an ideal gas. in a real engine, inlet flow may be all air, or it may be mixed with up to 7% fuel, either gaseous or as liquid droplets, or both. during combustion, the composition is then changed to a gas mixture of mostly co2, h2 o and n2 , with lesser amounts of co and hydrocarbon vapor. 3. there are heat losses during the cycle of a real engine which are neglected in air-standard analysis. heat loss during combustion lowers actual peak temperature and pressure from what is protected. the actual power stroke, therefore starts at a lower pressure, and the work output during expansion is decreased. 4. combustion requires a short but finite time to occur, and heat addition is not instantaneous at tdc, as approximated in an otto cycle. a fast but finite flame speed is described in an engine. this results in a finite rate of pressure rise in the cylinders, a steady force increase on the piston face, and a smooth engine cycle. because of the finite time required , combustion is started before tdc and ends after tdc, not at constant volume as in airstandard analysis. by starting combustion tdc, another loss in the combustion process of an actual engine occurs because combustion mailto:hayder_abed2002@yahoo.com hayder abed dhahad al-khwarizmi engineering journal, vol. 7, no. 3, pp 68 77 (2011) 69 efficiency is less than 100%. this happens because of the less than perfect mixing, local variations in temperature and air-fuel due to turbulence, flame quenching, etc. si engines will generally have a combustion efficiency of about 95%, while ci combustion engines are generally about 98% efficient [8]. 5. the blow down process requires a finite real time and a finite cycle time, and does not occur at constant volume as in air-standard analysis. for this reason, the exhaust valve must open 400 to 600 before bdc, and the output work at the latter end of expansion is lost [5]. 6. the intake valve is not closed until after bottom-date center at the end of the intake stroke in an actual engine. because of the flow restriction of the valve, air is still entering the cycle at bdc, and volumetric efficiency would be lower if the valve closed here. because of this, however, actual compression does not start at bdc, but only after the inlet valve closes. with ignition then, occurring before top dead center, temperature and pressure rise before combustion is less than predicted by airstandard analysis [10]. 7. engine valves require a finite time to actuate. ideally, valves would open and close instantaneously, but this is not possible when using a cam follower and this result in fast but finite valve actuation [7]. because of these differences which real airfuel cycles have from the ideal cycles, result from air-standard analysis will have errors and will deviate from actual conditions. interestingly, however, the errors are not great, and property values of temperature and pressure are very representative of actual engine values. tayler[3] shows that over a large range of operating variables the indicated thermal efficiency of an actual si four-stroke cycle engine can be approximated by 85% of otto thermal efficiency. three cycles have a great importance during the analysis of i.c. engine; they are: 1. otto cycle (constant volume cycle ) 2. diesel cycle 3. dual combustion cycle otto cycle represents the theoretical basis of spark ignition engine while the diesel cycle represents the theoretical basis of compression ignition engine. the modern high speed compression ignition engine works with dual combustion cycle. otto cycle is distinguished among the three cycles that it has the highest thermal efficiency when the three cycles work at the same compression ratio. otto cycle efficiency is given by the equation [5] 1 11 −−= γη cr …(1) while the efficiency of diesel cycle is given by the equation [5] ( )      − −= − − 1 11 1 1 ργ ρ η γ γ cr …(2) the engine works by otto cycle is limited by certain compression ratio due to fuel octane number requirements [9], while diesel engine works at high compression, the ratio is nearly three times of otto compression ratio. this makes it have the highest efficiency rather than when the engine works by otto cycle. the heat addition at constant volume in otto cycle makes it more efficient than the other cycle when they work at the same compression ratio, while the diesel cycle is distinguished by the ability of work at high compression ratio. from this the idea of isolated combustion and diluted expansion (icade) cycle was born. the (icade) cycle introduced by (jone l. loth & eric loth ) (4) include the two advantages: heat addition at constant volume, and high compression ratio. 2. icade cycle description a new stratified charge internal combustion engine named the “isolated combustion and diluted expansion (icade)” engine is described here. it combines the advantage of constant volume combustion and compression ratio of the diesel cycle. unlike most designs using an isolated combustion camber, the icade cycle does not require any external mechanical controls. at about ο30 crank angle before the piston reaches tdc, the cylinder is divided in two parts by an especially design dome mounted on top of the piston. each part contains roughly the same mass of air. the first part on top of the dome constitutes the combustion chamber. its compression ratio is designed for the octane number of the fuel at hand. the second part is the remaining cylinder volume above the piston. that part is further compressed to about half the volume of the combustion chamber. this higher compression ratio is what improves the efficiency. fuel is injected directly into the isolated combustion chamber. a unique feature of this hayder abed dhahad al-khwarizmi engineering journal, vol. 7, no. 3, pp 68 77 (2011) 70 configuration is that the volume in the isolated combustion chamber varies a little over ο30 of crank angle. this allows even slow burning mixtures to burn at near constant volume, thereby producing high combustion pressurization. as soon as the combustion chamber pressure rises above that in the cylinder, a ball type check valve in the dome opens and the combustion products rush into the cylinder to mix with the compressed air. this dilution quenches all nox forming reactions and provides excess o2 to reduce unburned hydrocarbons. the dilution of the combustion products prier to expansion simulates a stratified charge engine. such a stratified engine produces less power per unit of displacement volume. for temporary increased power production additional fuel can be burned by admitting very lean fuel/air mixture instead of pure air. the mixture must be lean enough that compression ignition is not possible. a schematic of the engine geometry is shown in fig.(1). depending on the ratio of dome height to piston stroke, the dome starts to isolate the combustion chamber at about ο30 before tdc. although the dome is actually a “leaky valve”, the mass above the dome undergoes very little volume change or change or compression and therefore remains at near constant volume at about ο30 of crank angle. near constant volume combustion has several advantages. 1. fuel injected in the combustion chamber can be ignored early without power loss associated with compression of the combustion product. 2. fuel cannot leak into the cylinder because the pressure there is higher. 3. even slow burning fuels have adequate time for combustion thereby producing significant combustion pressurization. 4. only after combustion pressurization, will the ball be forced of its seat to allow rapid mixing of the combustion products with compressed air above the piston expansion. no external mechanisms are needed to control the opening and closing of the ball valve. at the start of the compression stroke the inertia of the ball forces it into the piston. there it accelerates with the piston velocity to reach a maximum velocity at midpoint of the stoke. from there on the piston slows down but the ball continues at constant velocity and thus floats away from the piston to seal off the dome outlet. this occurs just before the dome type isolation valves closes. as the air in the cylinder is further compressed, the resulting pressure differential maintains the check valve in the closed piston. not until the pressure above the ball exceeds the cylinder pressure by 35 psi will the ball unseat itself and allow the combustion products to rush into the cylinder and mix with the air. the resulting dilution and temperature reduction terminates any no4 forming reactions and reduces the heat losses to the cylinder walls during expansion. to further reduce heat loss the combustion chamber could be insulated as direct fuel injection is used and the walls there need not support any piston skirt force. fig.1. icade engine layout. the advantages of the icade cycle over the otto cycle are [4]: 1. the cylinder compression ratio rp is higher than the combustion chamber compression ratio rc. thus the average compression ratio is higher than for the otto cycle, which explains the higher icade cycle efficiency. 2. the icade cycle has the combustion products quench from ti4 down to ti6 immediately after combustion to halt the formation of nox . this is unlike the otto cycle where the temperature drops slowly and nox formation can continue during piston expansion. 3. the icade engine can be lighter for the same volume v1 because the maximum cylinder pressure pi6 is lower than p3 in the otto cycle. hayder abed dhahad al-khwarizmi engineering journal, vol. 7, no. 3, pp 68 77 (2011) 71 however for the same power rating the structure weight will be about the same. 4. if the isolation valve closure could be modulated or the combustion chamber volume be reduced at part power operation, then the need for an engine throttle valve and associated efficiency loss would be eliminated. the reduced mixture temperature ti6 would further lower cycle wall heat losses. but for the configuration shown in fig.(1) these schemes are not possible as the valve opens and closes automatically under the action of inertia and pressure. the disadvantages of the icade cycle over the otto cycle are: 1. required direct combustion chamber fuel injection. but this can be done slowly during about ο30 of crank angle. 2. additional mechanical complexity such as a combustion chamber isolation valve, like a dome on the piston with ball type check valve, is needed. 3. although for a given engine volume v1 the icade cycle engine weight is lower and the efficiency is higher than for the otto cycle, the power output per unit volume is reduced. for example if the icade cycle combustion camber volume vc is half of the otto cycle volume v2 , then the fuel burned per cycle is half and the engine power output is reduced accordingly. 3. analysis of the icade cycle making a comparative analysis between the icade and the otto cycle, it is found both cycles are operated at identical conditions such as [ fuel – air ratio , combustion compression ratio ( rc) intake conditions ( 1,1,1 tpv and intake mass m ) ]. the icade cycles differ in that the air remaining in the cylinder] mp = m-mc ]is compressed further by the cylinder compression ratio ( rp ) with limitation pi5 < pi4 as shown in fig. (2) which shows the pressure as a function of crank angle for both otto and icade cycles . both cycles have the same maximum temperature ratio;         == 1 4 1 3 it it t t tr at tdc after combustion the ball type check valve opens and the combustion products mix with the lower air inside the cylinder. m cm m pm rm −== 1 fig.2. pressure as a function of crank angle for both otto and icade cycle. station 1:otto cycle icade cycle with volume 1v , at the start of the compression stroke, with crank angle 0=θ degrees to combustion chamber at compression ratio (rc). itr vp m 1 11= …(3) 2 1 v v cr = (otto cycle) …(4) ( )mr iv v cr −×         = 1 3 1 (icade cycle) …(5) station 2:(otto cycle only) at 180=θ degrees with volume 2v ( ) 111 1 2 1 2 −     −= −         = γ γ γγ γ crt t p p …(6) 0 90 180 270 360 10 20 30 40 50 60 2i 2 ,3i 5i 6i 3 ,4i pressure-crank angle for otto and icade cycle crank angle p /p 1 rc=8 rp=16 tr=7 riso=6.4 oto icade icade hayder abed dhahad al-khwarizmi engineering journal, vol. 7, no. 3, pp 68 77 (2011) 72 station 2i :[ icade cycle only ] at 150=θ degrees. compression ratio at point of isolation is; isov v isor 1= …(7) ( ) 111 1 2 1 2 −     −= −         = γ γ γγ γ isor t it p ip …(8) station 3i : [ icade cycle only ] with volume vi3 at reesdeg180=θ ( ) 111 1 3 1 3 −     −= −         = γ γ γγ γ crt it p ip …(9) note that 23 23 pip tit = = but with mass mc instead of m and volume vc . station 3:[ otto cycle only ] at 180=θ degrees with mass = m 23 vv = combustion at constant volume with temperature ratio 1 3 t t tr = which depended on fuel/ air ratio. ( ) ( ) 1 1 2 1 2 3 2 3 −       =         == γ cr tr t t tr t t p p …(10) station 4i :[ icade cycle only ] at 180=θ degrees with mass = mc iviv 34 = combustion at constant volume with temperature ratio;         = it it tr 4 34 tit = …(11) ( ) ( ) 1 1 3 1. 3 4 3 4 −       =         = γ cr tr it t tr it it ip ip …(12) 2 3 3 4 p p ip ip = …(13) but 23 pip = 34 pip = …(14) station 5i :[ icade cycle] at 180=θ degrees, icade cycle isolated cylinder clearance volume vp . pr mr v pv = 1 …(15) ( ) cr mr v cv − = 1 1 …(16) ( ) 1 1 5 −= γ pr t it …(17) ( ) γ γ γγ γ 1 1 1 1 5 1 5 −     −= −         = pr t it p ip …(18) station 6i :[ icade cycle] at 180=θ digrees, at this point the piston is still at tdc and the ball type check valve is open which allows the high pressure combustion products at pi4 to mix with the air in the cylinder at pressure ip5 . as this process is adiabatic and at constant volume, the internal energy does not change and the final mixture temperature as given by: ( ) ( ) 1 5 1 41 1 6 t it mr t it mr t it +−= …(19)         − +=+= cr mr pr mrvcvvpiv )1( 16 …(20) from the equation of state: cr mr pr mr t it iv it t v p ip − +         == 1 1 6 6 6* 1 1 1 6 …(21) hayder abed dhahad al-khwarizmi engineering journal, vol. 7, no. 3, pp 68 77 (2011) 73 station 4 :[ otto cycle] at 360=θ digrees, the final expansion of the otto cycle ends up at 14 vv = , with temperature 4t γ       = crp p 1 3 4 …(22) r crp p p p       = 1 1 3 1 4 …(23) γ γ γ 1 1 1 3 1 4 −               = crt t t t …(24) γ γ γ 1 1 1 4 −               = cr tr t t …(25) station 7i :[ icade cycle] the final expansion of the icade cycle ends up at 17 vv i = with temperature it 7 1 1 1 6 1 7 6 1 6 1 7 −         − += −         = γγ cr mr pr mr t it iv iv t it t it …(26) for the icade cycle: the expansion work ( )76 iiv ttmc −= …(27) the compression work ( ) ( )iivciivp ttcmttcm 1315 −+−= …(28) the heat supplied = ( )iivc ttcm 34 − …(29) ( )[ ] ( ) ( )[ ] ( )iivc iivciivpiiv thi ttcm ttcmttcmttmc 34 131576 − −+−−− =η …( 30) ( ) ( ) ( ) ( )ii c ii c ii p ii ith tt m m tt m mtt m m tt 34 131576 − −−−−− =η …(31) by substituting the temperatures from the above equations this expression is reduce to: ( )1 1 − −= γ η c ith r bicade …(32) where b is given by : ( ) ( ) ( ) 1)1( 111 1 1 1 −+ − −         + −       −+ = − − − mr r trmr mr r trmrmr r r mr b c pc p γ γ γ …(33) the cycle efficiency improvement is shown in fig. (3) as a function of the added piston compression after isolation as given by ( rp / rc ). the icade cycle reduces to the otto cycle for the case when (mp) goes to zero, or if the mass (mp) has no extra compression or cp rr = in either case coefficient b is reduced to 1. fig.3. comparison of icade and otto cycle efficiency. 4. discussion of results 4.1. isolated air mass (charge stratification) effect both cycles are based on the same intake mass m, p, t, and combustion compression ratio cr . cm is the mass isolated in the combustion chamber which compressed by cr and mixed with fuel to ignite. when we reduces mc, mp will increase , thus mr will increase; this means the amount of mass compressed by rp will increase and the cycle efficiency will approach to diesel cycle efficiency, but this will decrease the power generation from an engine. 1 1.2 1.4 1.6 1.8 2 2.2 2.4 2.6 2.8 3 1 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.1 added poston compression rp/rc ic a d e o v e r o tt o t h e r m a l e ff ic ie n c y thermal efficiency improvement tr=7 mr=0.5 rc=6 rc=8 rc=10 rc=12 hayder abed dhahad al-khwarizmi engineering journal, vol. 7, no. 3, pp 68 77 (2011) 74 the effect of isolated air mass is shown in fig. (4), the icade cycle efficiency increases with the decrease of isolated air mass[ increases of mr]; the improvement over the otto cycle efficiency is about 10% when (mr = 0.6) an increase of mr means that the stratification portion of the mass mp will increase; this will quench all nox forming reactions and provide excess o2 to reduce unburned hydrocarbons. more decreases in isolated air mass are not practical because of power losses. fig.4. effect of charge stratification on icade efficiency improvement. 4.2. fuel/ air ratio effect at an increase f/a ratio inside the combustion chamber, this will lead to the increase of release energy, and so increase the maximum temperature inside the combustion tr the effect of a f ratio on the efficiency of (icade) cycle is shown in fig. (5). we notice the efficiency increase with tr increasing so as the improvement over the otto cycles thermal efficiency reaches 9% at tr = 8, with the increasing of power generation at the cycle. but on the other hand the increasing of f/ a ratio will lead to the increasing of unburned hydrocarbons. fig.(6) show the improvement of efficiency over the efficiency of otto cycle at different f/ a values and different values of mr . we can notice that the increasing of efficiency of cycle with the increasing mr and tr. in fact to obtain the best performance it is advised to work at high f/ a and high mr but according to the power requirement limitation. the use of greater mr means the existence of great amount of air outside combustion chamber, so reducing the unburned hydrocarbons. fig. (7) shows the improvement of cycle efficiency over otto efficiency at (mr = 0.6, tr= 8) compared to the efficiency at (mr = 0.5, tr= 7). the use of (mr= 0.6, tr= 8) means the highest efficiency, the greatest power and little unburned hydrocarbons, but this will be accompanied with the increase of heat transfer to the cylinder wall in expansion stroke because of the raising of it6 value. fig.5. effect of fuel/ air ratio on icade efficiency improvement. 1 1.2 1.4 1.6 1.8 2 2.2 2.4 2.6 2.8 3 1 1.02 1.04 1.06 1.08 1.1 1.12 added poston compression rp/rc ic a d e o v e r o tt o t h e r m a l e ff ic ie n c y thermal efficiency improvement tr=7 rc=6 rp=6 -18 mr=0.60 mr=0.55 mr=0.50 mr=0.45 mr=0.40 1 1.2 1.4 1.6 1.8 2 2.2 2.4 2.6 2.8 3 1 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.1 added poston compression rp/rc ic a d e o v e r o tt o t h e r m a l e ff ic ie n c y thermal efficiency improvement mr=0.5 rc=6 rp=6 -18 tr=8 tr=7.5 tr=7 tr=6.5 tr=6 0.4 0.45 0.5 0.55 0.6 0.65 1 1.05 1.1 1.15 mr ic a d e o v e r o tt o t h e r m a l e ff ic ie n c y thermal efficiency improvement rp/rc=2 tr=5 tr=6 tr=7 tr=8 hayder abed dhahad al-khwarizmi engineering journal, vol. 7, no. 3, pp 68 77 (2011) 75 fig.6. combined effect of charge stratification and fuel/air ratio. fig.7. comparison of icade efficiency at different values of tr and mr. fig.8. temperature as function of crank angle for both icade and otto cycles 5. conclusions 1conversion to the icade cycle benefits the efficiency of spark ignition engines because the compression ratio is doubled and combustion pressurization is improved, even with slowly burning fuels. 2it will be able to improve the cycle efficiency through the control of f/a and the amount of isolated air. 3with the decreasing of the isolated air in combustion chamber, the efficiency of cycle will increase but power generation will decrease with the decreasing of isolated air amount. 4during the increase f/a which means the highest maximum temperature of the cycle tr, the cycle efficiency will increase. 5the combustion product dilution provides the excess air needed to minimize emissions of unburned hydrocarbons and reduce nox formation. 6 detonation is not expected to be too harmful as only the relatively small piston dome is subjected to the shock wave. also the combustion product compression by the piston will be small [5]. nomenclature b coefficient defined in text cv specific heat at constant volume ( kj/kg.k ) d piston diameter ( m ) dc combustion chamber diameter ( m ) dr combustion chamber to piston diameter ratio m total cylinder intake air mass ( kg ) mc isolated combustion chamber mass ( kg ) mp isolated cylinder air mass ( kg ) mr charge stratification, mr = mp/m p( ) otto cycle pressure at station ( ) ( pa ) p1 inlet reference pressure = pi1 ( pa ) pi( ) icade cycle pressure at station ( ) ( pa ) s piston stroke ( m ) rc max. combustion chamber compression ratio riso compression ratio at point of isolation rp cylinder compression ratio t( ) otto cycle temperature at station ( ) ( k ) ti( ) icade cycle temperature at station ( ) (k) t1 inlet reference temperature = ti1 ( k ) tr maximum cycle temperature divided by t1 v1 maximum intake volume with piston at bdc ( m3) vc combustion chamber volume ( m3) 1 1.2 1.4 1.6 1.8 2 2.2 2.4 2.6 2.8 3 1 1.02 1.04 1.06 1.08 1.1 1.12 1.14 added poston compression rp/rc ic a d e o v e r o tt o t h e r m a l e ff ic ie n c y thermal efficiency improvement rc=6 tr=8 mr=0.6 rc=6 tr=7 mr=0.5 0 90 180 270 360 1 2 3 4 5 6 7 8 temperature-crank angle for otto and icade cycle crank angle t/ t1 rc=8 rp=16 tr=7 riso=6.4 2i 2 , 3i 5i 6i 3 ,4i oto icade icade hayder abed dhahad al-khwarizmi engineering journal, vol. 7, no. 3, pp 68 77 (2011) 76 vd piston displacemen volume ( m3) vp cylinder clearance volume , piston at tdc ( m3) v( ) volume with piston at station ( ) ( m3) γ specific heat ratio ήth thermal efficiency θ compression crank angle starting at bdc ρ cutoff ratio 6. references [1] willar w. pulkrabek (engineering fundamentals of the internal combustion engine) prentice hall, new jersey, 1996. [2] keenan,j.h., j.chao, and j. kaye (gas tablesinternational version, 2nd ed., malabar, fl: krieger, 1992. [3] taylor, c.f., (the internal combustion engine in theory and practice) cambridge, ma: m.lt.press, 1977. [4] loth,j. l. loth,e. (isolated combustion and diluted expansion (icade) internal combustion engine cycle analysis ) icevol. 20, alternate fuels , engine performance and emissions asme 1993. [5] heywood, j. b. (internal combustion engines fundamentals) mcgraw-hill, new york, 1988. [6] ikegami.m., m.shioji, and k.nishimoto, (turbulence intensity and spatial integral scale during compression and expansion strokes in a fourcycle reciprocating engine) sae paper 870372, 1987. [7] king, r.s. (the impact of natural gas composition on fuel metering and engine operational characteristics), sae technical paper 9205931992. [8] caton, j.a., (a review of investigations using the second-law of thermodynamics to study ic engines) society of automotive engineers, in “si combustion” sp-1517, pp. 9-22,paper no. 2000-01-1081,at the 2000 sae international congress and exposition ,cobo center detroit ,mi,06-09 march 2000. [9] caton , j.a., (operating characteristics of a spark ignition engine using the second-law of thermodynamics: effects of speed and load) society of automotive engineers, in “modeling of si engines” sp-1511, pp. 1-17, paper no. 2000-01-0952,at the 2000 sae international congress and exposition ,cobo center detroit, mi,06-09 march 2000. [10] caton, j.a., (a multiple-zone cycle simulation for spark ignition engine: thermodynamic details) in large-bore engines, fuel effects, homogeneous charge compression ignition, engine performance and simulation, vol.2, icevol.37-2, proceedings or the 2001 fall technical conference, ed. v. w. wong, the asme internal combustion engine division, paper no. 2001-ice-412, pp.4158, argonne, il, 23-26-september 2001. [11] shkolnik,n., (high efficiency hybrid cycle engine) proceedings of icef 2005, asme internal combustion engine division 2005, 11-14 september 2005, ottawa, canada. )2011( 68 77 ، صفحة3، العدد 7مجلة الخوارزمي الھندسیة المجلد حیدر عبد ضھد 77 الھواء على كفاءة دورة محرك/ تأثیر الشحنة المطبقة ونسبة الوقود ( icade )االحتراق الداخلي حیدر عبد ضھد الجامعة التكنولوجیة/ مركز التدریب والمعامل الخالصة اق بثبوت الحجم في دورة اوتو مع نسبة تجمع بین ممیزات االحتر (icade )دورة محرك االحتراق الداخلي ذات االحتراق المعزول والتمدد المخفف على كفاءة الدورة وقد تبین من خالل التحلیل بان تقلیل ) الشحنة المطبقة ( ھذا البحث تأثیر كتلة الھواء المعزول یدرساالنضغاط العالیة في دورة دیزل ، وكذلك الھایدرو noxلمخفف سیؤدي إلى تخمید تكون اكاسید الناتروجین كتلة الھواء المعزول یودي إلى زیادة كفاءة الدورة ، كما ان زیادة كمیة الھواء ا الھواء على كفاءة الدورة حیث تبین بان زیادة نسبة الوقود م الھواء سیؤدي إلى زیادة كفاءة / كاربونات الغیر محترقة ، كما تم دارسة تأثیر نسبة الوقود .الدورة زينة ومنى al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 7784 (2013) estimation of snr including quantization error of multiwavelength lidar receiver zena a. abed* muna m. hummady** *,**department of information and communication engineering/ al-khwarizmi college of engineering/ university of baghdad *email: baghdad_zaa@yahoo.com **email: muna_hummady@yahoo.com (received 12 november 2012; accepted 23 april 2013) abstract this paper comprises the design and operation of mono-static backscatter lidar station based on a pulsed nd: yag laser that operates at multiple wavelengths. the three-color lidar laser transmitter is based on the collinear fundamental 1064 nm, second harmonic 532 nm and a third harmonic 355nm output of a nd:yag laser. the most important parameter of lidar especially daytime operations is the signal-to-noise ratio (snr) which gives some instructions in designing of lidar and it is often limit the effective range. the reason is that noises or interferences always badly affect the measured results. the inversion algorithms have been developed for the study of atmospheric aerosols. signal-tonoise ratio (snr) of three-color channel receivers were presented while averaging together 1, 20, 50 and 100 lidar returns and combined to the signal to noise ratio associated with the quantization process for each channel. keywords: lidar, signal-to-noise ratio, aerosols, noise, laser radar. 1. introduction lidar is an acronym of (light detection and ranging); it works on the same principal as ordinary (radar), except that light is used instead of radio waves. the basic principles are similar, i.e. a short pulse of light is transmitted, scatters from an object and returns to the receiver. in atmosphere, the lidar pulse is scattered from molecules which are small compared to the wavelength of the radiation (rayleigh or raman scattering), from particles of dust or aerosols with sizes on the order of the wavelength of the radiation or larger (mie scattering). this process is important in the lower regions of the atmosphere (from the ground to about 25 km) where dust and aerosols are significant components of the atmosphere, or from pieces at specific wavelengths (resonance fluorescence) [1,2]. this paper comprises the computational assessment of an elastic lidar system based on a pulsed nd: yag laser that operates at multiple wavelengths (355,532 and 1064nm) for retrievals of troposphere aerosol, cloud characteristic and water vapor vertical profiles. 2. description of multi-wavelength lidar instrument the design of the lidar instrument presented in this paper is based on the authors design of several previous lidar systems with several key exceptions [3]. the lidar instrument presented here makes use of three wavelengths of light, and is specifically designed to study atmospheric aerosols. important design considerations specific to aerosol study are that the laser beam and the telescope field of view (fov) are fully overlapped (the laser beam transverse energy profile fits within the telescope field of view) at ranges where aerosols are to be mailto:baghdad_zaa@yahoo.com mailto:muna_hummady@yahoo.com zena a. abed al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 7774 (2013) 78 studied, and that each detector (there is one detector for each of the three wavelengths of light) sees the same field of view. additionally, the vertical resolution, which is determined primarily by the laser pulse-width, should be small enough to reasonably observe atmospheric aerosols. other design parameters of note are that the laser should emit enough energy per pulse to adequately illuminate the atmosphere, and that background light from the sky is somehow prevented (as much as possible) from striking the optical detectors. as the light source for the three-wavelength lidar instrument, nd:yag laser was chosen because fundamental, second and third harmonic frequencies emitted by such a laser are adequate for studying atmospheric aerosols, and optical components optimized for their harmonic wavelengths are relatively easy and economical to obtain [4]. a schematic of the three-wavelength lidar instrument is shown in fig. 1. the lidar transmitter is 20 hz q-switched nd: yag laser. it produce light at the fundamental 1064 nm, second harmonic 532nm, and third harmonic 355 wavelengths. the laser beams are expanded and re-collimated using a diverging lens and incident on a dielectric mirrors that direct most of the collinear fundamental, second and third harmonic light into the atmosphere. the optical receiver for the three-color lidar instrument uses a 28 cm diameter schmidtcassegrain telescope to collect the light scattered by the atmosphere. since the optical power received by a lidar system is proportional to the physical area of the light collection optics, using as large a telescope as practicable is advantageous [5]. a gated pmt is used to monitor the 532 nm and 355 nm channels while an apd is used to monitor the 1064 nm channel. the electrical signals from the apd and pmt assemblies are digitized using a 14 bit 200 mhz a/d converter [5]. fig. 1. schematic diagram of three-color lidar instrument. 3. solving lidar equation (retrieval method) the lidar equation can be derived using the mie theory of scattering [6]. the equation defining the backscattered power received by a lidar system at any given time can be represented as a function of the light transmitted by the lidar attenuated by various factors and delayed by the round-trip travel time of that light, can be expressed as: ( ) = ( ) ∫ ′ ′ ( ) ( )τ …(1) where pt is the laser transmitter pulse power in watts, drec is the receiver optics diameter in m, c is the speed of light in m/s, τ is the laser pulse duration in seconds, β (r) is the backscatter coefficient with units of ( . ) , σ (r) is the extinction coefficient with units of ( . ), ϵ (λ) is the spectral transmission of the receiver optics at wavelength λ and ϵ (r) is the overlap function and is unitless. the overlap function, ϵ (r), refers to the overlap between the field of view of the telescope and the intensity profile of the laser as a function of range. the lidar inversion for the data collected with the two color lidar is based on methods developed by fernald et al [7]. taking into account multiple transmitter wavelengths, eq (1) can be re-written as: zena a. abed al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 7774 (2013) 79 ( )= , 2 ( , ) ∫ , ′ ′ ( ) ( ) …(2) and describes the amount of light received by the detectors from range bin r for a given wavelength λ. if all of the constants that are unique to the particular instrument for a particular wavelength are combined into one constant cλ where: = ( ) ( ) …(3) and the round trip atmospheric transmission is: (λ, ) = ∫ , ′ ′ …(4) eq (2) can be written as: ( ) = , ( , ) (λ, ) …(5) the assumption that the lidar inversion will only be completed when the lidar transmitter and the optical receiver are in full overlap allows as writing the overlap function ϵ(r) = 1. the two components, model of the atmosphere takes into account mie scattering from atmospheric aerosols and rayleigh scattering from atmospheric molecules. as described by wang et al. [8], the backscatter coefficient can be written in terms of these atmospheric scattering components as: ( , ) = ( , ) + ( , ) …(6) where β (λ, r) is the backscatter coefficient is associated with the atmospheric aerosols and β (λ, r) is the backscatter coefficient associated with the atmospheric molecules. similarly, the extinction coefficient can be written as [8]: ( , ) = ( , ) + ( , ) …(7) where σ (λ, r) is the extinction coefficient associated with the atmospheric aerosols and σ (λ, r) is the extinction coefficient associated with the atmospheric molecules. the relationship between the aerosol extinction and the aerosol backscatter is written as s (λ) = σ (λ, ) β (λ, ) and is known as lidar ratio. an equivalent lidar ratio can be written for the molecular backscatter and extinction as s (λ) = σ (λ, ) β (λ, ) . the lidar ratio is assumed to be constant with altitude and it is essential to this inversion technique. the assumption of the constant lidar ratio allows the total atmospheric transmission to be written as [8]: ( , ) = ( , ) ( , ) …(8) the atmospheric transmission due to atmospheric aerosols is: ( , ) = ( )∫ ( , ′) ′ …(9) and that the atmospheric transmission due to molecules is: ( , ) = ( )∫ ( , ′) ′ …(10) the molecular backscatter and extinction coefficients associated with the rayleigh scatter can be modeled. the molecular backscatter is given by: ( , ) = 374.28 ( ) ( ) /  …(11) where λ is given in nm and β (λ, r) is given in (m.s)-1, (ℎ) is the temperature in kelvin written as a function of height and h is the height above mean sea level given in meters. the temperature as a function of altitude h for 0 to 11 km can be modeled as [8]: (ℎ) = 288.15 − 0.00654ℎ …(12) the pressure over the same altitude range can be modeled as [9]: (ℎ) = 1.013 × 10 . ( ) . …(13) where the pressure, (ℎ) is given in pascal. knowing the molecular backscatter allows the molecular extinction to be calculated by using ( ) = . if the two components atmosphere model is applied to eqs (7, 8 and 10), the lidar equation for a two component atmosphere can be written as: ( ) = , [ ( , ) ( , )] ( , ) ( , ) …(14) by solving eq (14) for the aerosol backscatter coefficient, β (λ, r) using the techniques presented in [7], the lidar inversion can then be completed. taking the derivative of eq (9) with respect to r yields: ( , ) = −2 ( ) ( , ) ( , ) …(15) zena a. abed al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 7774 (2013) 80 solving eq (14) for ( , ) and substituting into eq (15) yields the first order differential equation [7]. ( , ) − 2 ( ) ( , ) ( , ) =− ( ) ( ) , ( , ) …(16) this first order differential equation in can be solved using the standard solution to get the transmission due to the aerosols. ( , ) = ( )∫ , ′ ′ × 1− ( ) ∫ ′ ( ′) , ( , ′) ( )∫ ( , ′′) ′′ ′ ′ …(17) if a range corrected return is written as: ( ) = ( ) …(18) and combined with the substitution of eq (17) and eq (10) into eq (14) the result is an equation which solves for the aerosol backscatter. ( , ) − ( , ) + ( ) ( ) ( ) ∫ ( , ′) ′ , ( )∫ ( ′) ( , ′) ( ) ∫ ( , ′′) ′′ ′ ′ …(19) the outgoing laser pulse and the telescope field of view are not in full overlap at altitudes below approximately 0.5 km; eq (19) must be slightly modified. this is done by having the lidar inversion take place over a range from some r0 to r rather than from 0 to r [7, 8]. if the laser and telescope come into full overlap at r0 then eq (19) is modified to instead be. ( , ) = − ( , ) + ( ) ( ) ( ) ∫ ( , ′) ′ , ( ) ( )∫ ( ′) ( , ′) ( ) ∫ ( , ′′) ′′ ′ ′ …(20) another change that should be made when considering the inversion from r0 is that the initial pulse energy must also be scaled. this is done by multiplying the initial power , by ( , 0) and setting it as the initial pulse energy. 4. snr of the lidar receiver the basic figure of merit for a lidar system is the signal to noise ratio (snr). other figures of merit, such as probability of detection and false alarm rate, are functions of the snr [10]. snr is an important measure of the error present in the lidar return signal acquired by the three wavelength lidar instrument, which for the 532 and 355 nm channels of the lidar instrument can be expressed as [11]: ∗( ) = ( ) ( ) …(21) where i(r) is the photocurrent at the anode of the pmt generated by photons scattered in (ma) from range r, e is the charge of an electron in (c), b is the bandwidth of the pmt in (ghz), g is the overall gain of the pmt, δ is the gain of an individual dynode stage of the pmt, idark is the dark current of the pmt (at the anode) in (na), k is boltzmann's constant in (jk-1), t is the temperature in kelvin and rl is the load resistance in (ω). the photocurrent i(r) can be expressed as a function of incident optical power as: ( ) ( ) …(22) where p(r) is the optical power of light scattered by the atmosphere at range r, v is the quantum efficiency of the pmt and h is planck's constant. the signal to noise ratio is similar for the 1064 nm channel of the lidar instrument, and can be expressed as [12]. ∗( ) = ( ) ( ( ) ) , …(23) where f is the excess noise factor, idark,nogain is the dark current that is not multiplied by the gain and g is the gain of the apd. the photocurrent i(r) can again be calculated using eq (21). according to utkin et al. [13], the signal to noise ratio (snr) of the lidar signal resulting from the accumulation of n lidar returns is given by the equation: 1( ) = ∗( ) …(24) signal to noise measurements show how well the desired signal can be distinguished from background noise. as the ratio of signal to noise approaches 1, the signal becomes difficult to distinguish from the noise. zena a. abed al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 7774 (2013) 81 5. quantization error quantization noise is added to the355 nm, 532 nm and the 1064 nm signals when they are digitized so that they can be stored and analyzed via computer. the digitization process consists of sampling the continuous voltage signal produced by the pmt and the apd at discrete time intervals, and rounding the voltage value of each sample to a discrete level that can be represented by the arbitrary number of bits used by the analog to digital (a/d) converter. the difference between the actual voltage value of the input signal from the lidar instrument and the discrete value assigned by the a/d card is the quantization noise. the quantization noise is essentially uniformly distributed random (white) noise because the signals from the pmt and apd in the threewavelength lidar instrument are usually within the range of the a/d converter and the quantization levels of the a/d card are uniform. the quantization process can therefore be modeled (in terms of the signal to noise ratio of the overall system) as adding uniformly distributed random noise to each sample. the signal to noise ratio associated with the quantization process that be modeled as [14]. 2 × …(25) where snr2 is the signal to noise ratio resulting from the quantization process, t+1 is the number of bits used to represent the quantized data, σ is the variance of the signal being quantized and x is the range of the quantized input (the variance and the input range should use the same units; in the case of the three-wavelength lidar instrument the units are volt2). using the following equation to combine the signal to noise ratio of the optical receiver to the signal to noise ratio associated with the quantization process [15]. …(26) 6. results and discussion range resolved plots of the signal to noise ratio for the three wavelength lidar instrument calculated using eqs (20-23) are shown in fig. 2 for the 355nm, 532 nm and 1064 nm channels of the lidar instrument, respectively. these signal to noise ratios were calculated using modeled atmospheric molecular backscatter profiles for each wavelength created using eqs (1113). other values used for the calculation 1 for the overlap function and 1.5 m for the range resolution. as is expected, the signal to noise ratio decays exponentially with range, and is improved by averaging multiple lidar returns together. the signal appears more degraded at longer heights where the signal to noise ratio is worse. the signal becomes clearly in appearance as more returns are averaged together. the signal to noise ratio associated with the quantization process are found to be 25, 24, 64db for 355, 532, 1064nm channels respectively. this means that the noise introduced by the digitization process is significant when compared to the noise introduced by the optical detectors. in [16], the signal to noise ratio associated with the quantization process is on the order of 1020 and were neglected. using eq (26) to combine the signal to noise ratio of the optical receiver to the signal to noise ratio associated with the quantization process for each channel, and is plotted in fig. 3. figures (2) and (3) (c) of 1064 nm channel shows higher snr with compared with 355 and 532 nm channels due to the using of (apd) detector which internally multiply the primary signal of photocurrent before it enters the following amplifier. this increases receiver sensitivity and the thermal noise is of lesser importance, so the optical detector noises usually dominated. zena a. abed al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 7774 (2013) 82 a b c fig. 2. a plot of signal to noise ratio of the lidar instrument while averaging together 1, 20, 50 and 100 lidar returns for (a) 355 nm channel (b) 532 nm channel (c) 1064 nm channel. a b c fig. 3. represents the combination of signal to noise ratio of the lidar instrument while averaging together 1, 20, 50 and 100 lidar returns for (a) 355 nm channel (b) 532 nm channel (c) 1064 nm channel. zena a. abed al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 7774 (2013) 83 7. conclusion in this paper, a general method for the validation and performance measurement of threecolor lidar system is proposed. we showed that the signal-to-noise ratio (snr) of the lidar backscattering dependinged on the presence of aerosol layers and often attenuate rapidly due to noise and interferences, such as dark current, background noise, electronics readout noise and atmospheric turbulence. although the quantization error was small but it cannot be neglected. the range accuracy of a lidar system depend could not on signal bandwidth and the receiver signal-to-noise ratio (snr). 8. references [1] v. a. kovalev and w. e. eichinger, elastic lidar: theory, practice and analysis methods. john wiley and sons, new york, 2004, p. 444. [2] c. weitkamp, lidar: rangeresolved optical sensing of the atmosphere, springer, 2005. [3] d. s. hoffman, a. r. nehrir, k. s. repasky, j. a. shaw, and j. l. carlsten,"rangeresolved optical detection of honeybees by use of wing-beat modulation of scattered light for locating land mines," applied optics, vol. 46, no. 15, pp. 3007-3012, 2007. [4] yasser. y. hassebo,"lidar signal-to noise ratio improvments consideration and techniques", doctor of philosophy in engineering, the city university of new york, 2007. [5] c hristian c. marchant, "retrieval of aerosol mass concentration from elastic lidar data", doctor of philosophy in electrical engineering, utah state university, logan, utah, 2012. [6] murray m. regush, development of a lidar for integration with the naval postgraduate school infrared search and target designation (nps-irstd) system, master's thesis, naval postgraduate school, monterey, california, june 1993. [7] f. g. fernald, b. m. herman, and j. a. reagan, "determination of aerosol height distributions by lidar," journal of applied meteorology, vol. 77, pp. 433-448, 1989. [8] x. wang, j. reagan, c. cattrall, and k. thome, "space borne lidar aerosol retrieval approaches based on improved aerosol model constraints," in ieee workshop on remote sensing of atmospheric aerosols, 2005, april, 2005, pp.36-42. [9] benjamin d. todt, "use of a two color lidar system to study atmospheric aerosols", master of science in physics, montana state university, 2010. [10] michael s. salisbury, paul f. mcmanamon, "signal to noise ratio improvement in lidar systems incorporating neodymium doped optical fiber preamplifiers," ieee aerospace and electronics conference, 1992, vol.3, pp. 1097 – 1103. [11] h. corp., high speed gated pmt module h7680, h7680-01 instruction manual. hamamatsu electron tube center, japan, 2005. [12] apd module c5460spl 6308 instruction manual. hamamatsu solid state division, japan, 2007. [13] a. utkin, "effective platform for lidar fire surveillance", optics & laser technology 41 (2009) 862–870. [14] a. v. oppenheim, r. w. shafer, and j. r. buck, discrete time signal processing. prentice hall, upper saddle river, nj, 1999, pp. 194-197. [15] m.richharia, "satellite communication systemsdesign principals', mcgraw-hill, pp. 117-118. [16] d. s. hoffman," two wavelength lidar instrument for atmospheric aerosol study", master of science in electrical engineering, montana state university, 2008. )2013(7784 ، صفحة2، العدد9مجلة الخوارزمي الھندسیة المجلد زینة عباس عبد 84 تخمین نسبة االشارة الى الضوضاء متضمنة خطأ التكمیم لمستقبل اللیدار متعدد األطوال الموجیة **منى مصطفى حمادي *زینة عباس عبد جامعة بغداد/ كلیة الھندسة الخوارزمي /قسم ھندسة المعلومات واالتصاالت **،* baghdad_zaa@yahoo.com :البرید االلكتروني* muna_hummady@yahoo.com: البرید االلكتروني** الخالصة ١٠٦٤یعتمد ھذا النوع من اللیدار على لیزر النیدیمیوم یاك بطول موجي . یتناول ھذا البحث تصمیم وعمل محطة اللیدار التي تعمل بعدة اطوال موجیة .نانومتر ٣٥٥نانومتر والتوافقیة الثالثة للیزر ذات الطول الموجي ٥٣٢والتوافقیة الثانیة بطول موجي نانومتر میم اللیدار نسبة االشارة الى الضوضاء تعتبر من اھم عوامل قیاس اداء اللیدار خاصة اثناء العمل بالنھار كما وتعطي ھذه النسبة مؤشرات مھمة في تص . وكذلك في مدى عمل اللیدار بسبب ما یوجد من ضوضاء في الجو وتداخالت تؤثر بشكل سلبي على النتائج المقاسة ، ١لللیدار عند جمع ) األطوال الموجیة الثالث(االنقالب في ھذ البحث كما تم حساب نسبة الضوضاء الى األشارة للقنوات الثالثة تم تطویر خوارزمیة . من األشارات المستلمة وجمع ھذه النسبة مع خطأ التكمیم وذلك لكل قناة من القنوات الثالث لللیدار ١٠٠و ٥٠ ، ٢٠ mailto:baghdad_zaa@yahoo.com mailto:muna_hummady@yahoo.com final4 ٣٨ al-khwarizmi engineering journal al-khwarizmi engineering journal, vol.1, no.1,pp 38-45, (2005) human face recognition using gabor filter and different self organizing maps neural networks dr. tarik zeyad electrical engineering dept./college of engineering/ university of baghdad abstract. this work implements the face recognition system based on two stages, the first stage is feature extraction stage and the second stage is the classification stage. the feature extraction stage consists of self-organizing maps (som) in a hierarchical format in conjunction with gabor filters and local image sampling. different types of som’s were used and a comparison between the results from these som’s was given. the next stage is the classification stage, and consists of self-organizing map neural network; the goal of this stage is to find the similar image to the input image. the proposal method algorithm implemented by using c++ packages, this work is successful classifier for a face database consist of 20 people with six images for each person and a measure of the time differences between the methods is given. keyword: self-organizing map, gabor filter. introduction. face recognition may seem an easy task for humans eyes providing that the recognized face is seen before, and yet computerized face recognition system still cannot achieve a completely reliable performance. the difficulties arise due to large variation in facial appearance, head size, orientation and change in environment conditions. such difficulties make face recognition one of the fundamental problems in pattern analysis. in recent years there has been a growing interest in machine recognition of faces due to potential commercial application such as film processing, law enforcement, person identification, access control systems, etc [1]. a complete conventional human face recognition system should include three stages. the first stage involves detecting the location of face in arbitrary images. the second stage requires extraction of pertinent features from the localized image obtained in the first stage. finally the third stage involves classification of facial images based on the derived feature vector obtained in the previous stage [2]. a number of image classification systems based on the combination of outputs of different classifier systems have been proposed. different structures for combining classifier systems can be grouped in three configurations. in the first group, the classifier systems are connected in cascade to create pipeline structure. tarik zeyad /al-khwarizmi engineering journal ,vol.1, no. 1,pp 38-45 (2005) ٣٩ in the second one, the classifier systems are used in parallel and their outputs are combined named parallel structure. finally the hybrid structure is a combination of the pipeline and parallel structures. [3]. finally in this work selforganizing map (som) neural network is used as the classifier. recently som neural networks have been found to be very attractive for many engineering problems. an important property of som neural networks is that they form a unifying link among many different research fields such as function approximation, regularization, noisy interpolation and pattern recognition. gabor wavelets. dennis gabor first proposed gabor functions as tools for signal detection in noise. gabor filter showed that there exists a “quantum principle” for information; the conjoint timefrequency domain for 1d signals must necessarily be quantized so that no signal or filter can occupy less than certain minimal area in it. however, there is a trade off between time resolution and frequency resolution. gabor discovered that gaussian modulated complex exponentials provide the best trade off. for such a case, the original gabor elementary functions are generated with a fixed gaussian, while the frequency of the modulating wave varies [4]. gabor filters, rediscovered and generalized to 2d, are now being used extensively in various computer vision applications. daugman [5] generalized gabor function to the following 2d form in order to model the receptive fields of the orientation selective simple cells: ( )         − σ =ψ σ σ 22 2 2 2 2 22 eee k x xkj xk i i i i rr rrr r …..(1) each iψ is a plane wave characterized by the vector ik r enveloped by a gaussian function, where σ is the standard deviation of this gaussian. the center frequency of ith filter given by the characteristic wave vector is shown below [5]:       θ θ =     = µ µ sink cosk k kk v v iy ix i r …..(2) having a scale and orientation given by (kv, θµ), the first term in the brackets (1) determines the oscillatory part of the kernel, and the second term compensates for the dc value of the kernel. subtracting the dc response, gabor filters becomes insensitive to the overall level of illumination [5]. since the gabor wavelet transform is introduced to computer vision area, one of the most important application areas for 2d gabor wavelet representation is face recognition. in the u.s. government activity (feret program) to find the best face recognition system, a system based on gabor wavelet representation of the face image is performed among other systems on several tests. although the recognition performance of this system shows qualitative similarities to that of humans by now means, it still leaves plenty of room for improvement. [6]. gabor filter can capture salient visual properties such as spatial localization, orientation selectivity, and spatial frequency characteristics. considering these excellent capacities and its great success in face recognition, gabor features are chosen to represent the face image. gabor filters are defined as follows: tarik zeyad /al-khwarizmi engineering journal ,vol.1, no. 1,pp 38-45 (2005) ٤٠ ( )         − σ =ψ σ σ 22 2 2 2 2 22 eee k x zkj zk v,u v,u v,u i r rr r …..(3) where uj vv,u ekk φ= and v max v f kk = gives the frequency and ( )π∈φ π =φ ,,u uu 0 8 gives the orientation and z=(x,y). zjk v,ue is the oscillatory wave function, whose real part and imaginary part are cosine function and sinusoid function respectively. in equation (2), v controls the scale of gabor filter, which mainly determines the center of the gabor filter in the frequency domain; u controls the orientation of gabor filters [4]. the gabor filters are used with the following parameters: five scales v ε { 0 , 1 , 2 , 3 , 4 , 5 } and eight orientations u ε { 0, 1 , 2 , 3 , 4 , 5 , 6 , 7 } with σ = 2π, maxk = π / 2, and f= 2 [7]. the proposed face recognition method the objective of this section is to put a block diagram which stands for the suggested model, convert each block into a suitable mathematical model , and finally define model parameters in order to improve its qualification , figure (1) shows the proposed face recognition model. tarik zeyad /al-khwarizmi engineering journal ,vol.1, no. 1,pp 38-45 (2005) ٤١ step -1 step-3 step -2 b the feature extraction model. step -4 c classification model. gabor feature extraction. the gabor filter has been successfully used in conjunction with the multilayer self-organizing maps (msom) as a feature extraction for face recognition. gabor filters are orientation and frequency sensitive band pass filters that provide optimal resolution in both the space and spatial-frequency domains. for these reasons, they are suitable for extracting frequency dependent information like edge features from a small area. gabor filters have also been used in other pattern recognition systems. the twodimensional gabor filter was described by equation (1). here linear and nonlinear shapes were chosen for the analysis using self-organizing maps. the linear shapes were squares, circles and hexagonal grids. the nonlinear grids were taken in a shape close to the cross. the feature extraction system is a combination of the gabor filter and three self-organizing maps (som). each time the system is applied to an image the output is a set of 500 feature values, corresponding to 500 x and y position on the original images. the two 2-dimension soms are trained by the unsupervised method, with each node storing the eight values corresponding to a gabor jet. the 1dimension som has 256 nodes and each map has six values. local image sampling. local image sampling is a used as an attempt to identify distinguishing features by presenting a small portion of the image to a system such as a selforganizing map. this som job is then to identify the presented image portion as a useful feature. thus by gabor feature extraction image sampling 1dimension som 2dimension som self organizing map (som) linear and nonlinear tarik zeyad /al-khwarizmi engineering journal ,vol.1, no. 1,pp 38-45 (2005) ٤٢ unsupervised learning the som will learn what different image portions represent. this is however not an ideal form of input into a one dimensional single layer som classifier as used in this work. there are two methods for obtaining the image sample vectors. these are described as follows: 1. the first method simply creates a vector from a local window on the image using the intensity values at each point in the window. let xij be the intensity at the ith row and the jth column of the given image. if the local window is a square of sides 2w + 1 long, centered on xij, then the vector associated with this window is simply [xi-w,j-w, xi-w,j-w+1, ... xij, ... xi+w,j+ w-1, xi+w,j+ w]. 2. the second method creates a representation of the local sample by forming a vector of the intensity of the centre pixel and all other pixels within the square. the vector is given by [xij – xi-w,j-w, xij – xi-w,j-w+1, ... xij, ... xij – xi+w,j+w-1, xij – xi+w,j+w]. the resulting representation becomes partially invariant to variations in the intensity of the complete sample. self feature clustering selforganizing maps. self-organizing maps (som) were initially developed by kohonen [8]. the som can be arranged to perform classification and feature extraction, although in this section the som is only presented as a feature extraction method, in the next section the som will be re-examined as a classifier. the theoretical study of the som will be explained in the next step, as this knowledge is not essential when comparing feature extraction methods. the som is an ideal method to use in conjunction with another feature extraction such as the gabor filter, or local image sampling as the feature values are topologically organized without using any prior knowledge. the 2-dimension som’s are trained by the unsupervised method, which is explained in the next step, with each node storing the eight values corresponding to a gabor jet. the 1dimension som has 256 nodes and each map has six values. the main advantages of this system are the reduced training time; data compression rate, distortion tolerant feature extraction, and the ability to train unsupervised the feature extraction stage. further analysis and expansion in terms of the face database size is required so that more quantitative results can be obtained to further determine the potential of som-based feature extraction and model-free networks for face recognition. classification. the self-organizing map as a classifier. the self-organizing map (som) as introduced by teuvo kohonen is one of the most widely used neural network structures in pattern recognition. the som has also been applied to various other applications such as speech analysis, process control systems, robotics and telecommunications [8]. self-organizing maps are generally less computationally expensive and perform better with large complex data compared to the traditional neural networks. the learning and topological arrangement of the self-organizing map has been observed to be similar to the behavior observed in higher animals’ primary visual cortex. thus going back to the original motivation of neural networks: to model the operation of the human brain. tarik zeyad /al-khwarizmi engineering journal ,vol.1, no. 1,pp 38-45 (2005) ٤٣ algorithm: 1. specify the type of the grid used in the som. 2.[ initialize weights] : initialize weights wij (1 < i < n) to small random values. set the initial radius of the neighborhood around node j to nj(t). 3.[present input]: the vector x0, x1, …, xn-1, where xi is the input to node j at time t. 4. [calculate distance dj] : calculate distance between the input and each node j, given by dj = σn [xi(t) – wij(t)]2 . 5. [determine dj*]: determine dj* which is the minimum value of dj. 6.[update weights] update weights for node j* and its neighbors defined by nj*(t). new weights are: wij(t+1) = wij(t) + a(t) [xi(t) – wij(t)] for j in nj*(t) where a(t) is a learning rate and both a(t) and nj*(t) decrease in t. 7. [repeat]: repeat by going to step 2 if the stopping condition, (t = b) is not satisfied, where b represents the total number of iterations. the time dependent values of a(t) and nj(t) are calculated by the following results of testing proposed algorithm. in this section, the properties of the suggested face recognition system are discussed using (20) different persons pictures. each person has (6) different images. each of these images is of 256 × 256 pixel. for the training of the feature extraction methods, gabor and local sampling, the number of reported iterations is constant. this is because for every time an image is used to train the three soms. the constant training time for all the input images is required; each som is actually presented with 500 sets of input data and is required to update the soms 500 times for each image. the two 2-d soms in the feature extraction contain (10x10) nodes and each node store eight values corresponding to gabor jets and the one-dimensional som has 256 nodes and stores six values. in local image sampling training, the number of features that is used is larger than for the gabor feature, the two 2dimension som contains (10×10) node and one dimension contains 256 nodes. this state of programs uses 7 exemplars. the following figure gives the output of a square linear som grid. figure (1). the program output with parameter (0.1) learning rate, 140 exemplars, and 0.9 threshold. conclusions. this work presents a human face recognition system based on the extraction of features using several types of som’s. for the linear grids som’s the hexagonal grid som gave the best results between the three linear grids used in the recognition procedure (square, circle and hexagonal) since the square contains more neighbors than the hexagonal and the circle grid contains neighbors on their circumference. the training procedure using the hexagonal neighbor is less than that of the other two linear grids used. tarik zeyad /al-khwarizmi engineering journal ,vol.1, no. 1,pp 38-45 (2005) ٤٤ the nonlinear som grid gave more accurate recognition than all linear grid som’s. the number of neighbors were less than the neighbors in all the linear grids. even so, the nonlinear som grid gave a better recognition speed and results. the total speed of the recognition process in all the grid methods depends on the size of the database used in the recognition process which were smaller in the nonlinear case. references 1. r. brunelli, t. poggio. face recognition: features versus temples. ieee transactions on pattern analysis and machine intelligence , 11(6):1042– 1052, 1993. 2. haddadnia, "n-feature neural network human face recognition", electrical and computer engineering department, university of windsor, 1997. 3. s. marcelja, “mathematical description of the responses of simple cortical cells”, j. optical soc. am., vol. 70, pp. 1297-1300, 1980. 4. d. gabor, “theory of communication”, j. iee, vol. 93, , pp. 429-459, 1946. 5. d. perkins, “ a definition of caricature and recognition”, studies in the anthropology of visual communication, vol. 2, pp. 1-24, 1975. 6. l. fausett, “fundamentals of neural networks”, prentice hall international, inc., 1994 7. p. yang, s. shan, w. gao, " face recognition using adaboosted feature", institute of computing technology of chinese academy science, 2000. 8. t. k. ho, j. j. hull and s. n. srihari, “decision combination in multiple classifier systems”, ieee trans. on patt. anal. and mach. intel., vol. 16, no. 1, pp. 66-75,jan. 1994 9. b. kepenekci, " face recognition using gabor wavelet transform'”, a thesis to the graduate school of natural sciences of the middle east technical university, the department of electrical and electronics engineering, 2001. tarik zeyad /al-khwarizmi engineering journal ,vol.1, no. 1,pp 38-45 (2005) ٤٥ وانواع مختلفة من الشبكات العصبية gaborتمييز االوجه البشرية باستعمال المرشح من نوع التنظيم الذاتي طارق زياد.د جامعة بغداد/كلية الهندسة/قسم الهندسة الكهربائية :الخالصة قاعدة بيانات والثانية هي المرحلة األولى هي بناء . تم في هذا البحث بناء منظومة لتمييز األوجه متكونة من مرحلتين في مرحلة بناء قاعدة البيانات تم استعمال شبكات عصبية نوع التنظيم الذاتي . هذه في عملية التمييز استعمال قواعد البيانات وبناءا عليه تم االستنتاج بأن النموذج الالخطي يعمل أفضل من ) خطية وال خطية(بأنواع مختلفة وتم المقارنة بين هذه األنواع . gaborالنموذج الخطي وكذلك استخدام المرشح نوع كلغة برمجة في ++cتم استخدام قاعدة بيانات متالفةمن عشرين شخص ولكل شخص تم استخدام ستة صور مع استخدام لغة . بناء المنظومة prediction of reaction kinetic of al-doura heavy naphtha reforming process using genetic algorithm al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 4761(2014) prediction of reaction kinetic of aldoura heavy naphtha reforming process using genetic algorithm ramzy h. saihod* zaidoon m. shakoor** abbas a. jawad*** * department of petroleum technology / university of technology ** department of chemical engineering / university of technology ***al-doura refinery / middle refinery company * e-mail: ramze_eng@yahoo.com ** e-mail: dr_zaidoon@yahoo.com ** e-mail: ahmed_198494@yahoo.com (received 31 october 2012; accepted 2 march 2014) abstract in this study, genetic algorithm was used to predict the reaction kinetics of iraqi heavy naphtha catalytic reforming process located in al-doura refinery in baghdad. one-dimensional steady state model was derived to describe commercial catalytic reforming unit consisting of four catalytic reforming reactors in series process. the experimental information (reformate composition and output temperature) for each four reactors collected at different operating conditions was used to predict the parameters of the proposed kinetic model. the kinetic model involving 24 components, 1 to 11 carbon atoms for paraffins and 6 to 11 carbon atom for naphthenes and aromatics with 71 reactions. the pre-exponential arrhenius constants and activation energies were determined after fine tuning of the model results with experimental data. the input to the optimization is the compositions for 21 components and the temperature for the effluent stream for each one of the four reactors within the reforming process while the output of optimization is 142 predicted kinetic parameters for 71 reactions within reforming process. the differential optimization technique using genetic algorithm to predict the parameters of the kinetic model. to validate the kinetic model, the simulation results of the model based on proposed kinetic model was compared with the experimental results. the comparison between the predicted and commercially results shows a good agreement, while the percentage of absolute error for aromatics compositions are (7.5, 2, 8.3, and 6.1%) and the temperature absolute percentage error are (0.49, 0.5, 0.01, and 0.3%) for four reactors respectively. keywords: heavy naphtha, reforming, genetic algorithm, optimization, reaction kinetic. 1. introduction the catalytic reforming process is one of the most critical operations in petroleum refineries. this process involves the reconstruction of lowoctane hydrocarbons in the naphtha into more valuable high-octane gasoline components without changing the boiling point range, production of aromatic feedstock for petrochemical industries also hydrogen and lighter hydrocarbons are obtained as side products [1, 2] . the catalytic reforming of naphtha involves reactions such as dehydrogenation, dehydrocyclization, hydrocracking, isomerization, and dehydroalkylation. the naphtha feed to reformer is very complex usually consisting of about three hundreds components with carbon number range from c5 – c12[3]. recent environment legislation in the united states has banned the use of lead as an additive for boosting antiknock properties of motor fuel. coupled with these stricter environmental regulations, there has been a consistent increase in the demand for higher octane number gasoline. this can be achieved by reforming the naphtha under more severe conditions, but this will also cause an increase mailto:ramze_eng@yahoo.com mailto:dr_zaidoon@yahoo.com mailto:ahmed_198494@yahoo.com ramzy h. saihod al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 4761 (2014) 48 in the rate of coke deposition, resulting in the reduction of cycle lengths of catalyst [4]. concerning the kinetic modeling of the naphtha processes smith 1959 [5] firstly proposed four lumps model by considering naphtha as three group regents, paraffins, naphthenes, and aromatic hydrocarbons. due to its simplicity, this model has been used in some recent reformer modeling work. krane et al., 1960[6] recognized the presence of various carbon numbers from c6 c10 as well as the difference between paraffins, naphthenes, and aromatics within each carbon number group. the model derived contained a reaction network of 20 different components. kmak 1972 [7] used langmuir kinetic model for reactors as first time. marin and coworkers 1982 [8] presented the reaction network for the whole naphtha, containing hydrocarbons in the carbon number fraction from c5-c10. the reaction network included 23 pseudo components and used hougen-watson type rate equations. ramage et al., 1987 [9] decided to develop a comprehensive kinetic model which (involving a reasonable number of group components and pathway) would capture the reactivity differences between particular raw materials. their studies led to the construction of mobil kinetic model of the reforming process (kinptr start of cycle and deactivation kinetics). taskar 1997 [10] developed a detailed kinetic scheme involving 35 pseudo components connected by a network of 36 reactions in the c5 – c10 range. deactivation of the catalyst was modeled by including the corresponding equations for coking kinetics. jorge 2000 [11] proposed a kinetic model for the naphtha catalytic reforming process (mathematical representation of the reaction that take place) and carbon number ranging from 111 atoms for paraffins , 6-11 for naphthenes, and aromatics. the kinetic parameters values were estimated using experimental information obtained in three fixed-bed pilot plant. weifeng 2003 [12] developed mathematical model for simulation and optimization of commercial naphtha catalytic reformers with four reactors in series. the model along with deactivation function of catalyst can monitor the reformer performance with time on stream. arani 2010 [13] simulated a dynamic model of the catalytic naphtha reformer process by matlab software. the kinetic parameters of model are based on the steady state condition and obtained from a commercial plant data furnished by a domestic petroleum refinery. askari 2012 [1] developed model for simulating catalytic reforming unit with four reactors in series by using hysys-refinery software. the results are validated by operating data, taken from the esfahan oil refinery catalytic reforming unit. in the industrial applications of reaction kinetics, the estimation of parameters in kinetic expressions from data series is essential for the design, optimization, and control of many chemical systems. the use of process models as a tool for simulation of commercial process has been growing rapidly. the advantage of utilizing rigorous mathematical models as compared to empirical approaches is related to the fact that the prediction accuracy of rigours models can be significantly superior over a wide operating range. to design new catalytic reforming process or to optimize the existing ones, an appropriate kinetic model to represent the reactions within the process is needed. therefore the aim of this study is to determine the values of kinetic model parameters for iraqi heavy naphtha reforming process by using differential optimization technique (genetic algorithm). 2. process description the process flow diagram of the reforming process is shown in figure 1. the commercial semi-regenerative catalytic naphtha reforming contains four fixed-bed adiabatically operated reactors in series. the naphtha used as feedstock which contains a mixture of paraffins, naphthenes, and aromatics in the carbon number range c4-c11 was combined with a recycle gas stream containing 60 – 90 mol% hydrogen. the used catalyst is pt-re/al2o3 which is bifunctional bimetallic catalyst providing the metal function and the acid function. usual catalytic reforming consists of multiple reactors (three or four) with heaters between the reactors to maintain reaction temperature at operable levels, since the major reactions in the first reactor dehydrogenation of naphthenes, which are endothermic and very fast, causing a very sharp temperature drop in the first reactor. as the total reactor charge passes through the sequence of heating and reacting, the reactions become less and less endothermic and temperature differential across the reactors decreases. the product from the fourth reactor is cooled and then enters to the product separator. the flashed vapor circulates to combine the naphtha ramzy h. saihod al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 4761 (2014) 49 feedstock as recycle gas. extra hydrogen from the separator is sent to other hydrogen consuming units in the refinery. the separated liquid that mainly included the desired aromatics together with heavy paraffins and light gases is sent to the reformate stabilizer. reformate off the bottom of the stabilizer is sent to storage for gasoline blending. table (1) shows the design parameters and operating conditions of the catalytic reformers of al-doura refinery in baghdad. the operating conditions of this unit were: 470 °c inlet temperature, 27.5 bar reactor pressure, and the feedstock flow rate of 33.5 m 3 /hr. fig. 1. process flow of four reactors naphtha reforming process. table 1, operating conditions of heavy naphtha reforming process. reactor number 1 2 3 4 catalyst weight kg 2700 4500 4750 5750 inlet temperature c 470 468 468 468 reactor length m 6 6 6 6 reactor diameter m 2.4 2.4 2.4 2.4 reactor 2 reactor 1 reactor 3 reactor 4 header 1 header 2 header 3 header 4 recycle gas compressor separator feed reformate cooler heat exchanger off gas ramzy h. saihod al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 4761 (2014) 50 ak taj ii p p ttr e kk                      11 3. mathematical model the following assumptions were considered in the present mathematical model: 1. the system was in a steady state. 2. the variation in the radial direction was negligible. 3. all reactions were in homogenous phase. 4. all reactions are pseudo first order with respect to hydrocarbon. the equations of mathematical model results from application of material and energy balance principles in a differential volume [14] .  i m i i r whsvz wtm dz dc    1 . . …(1)          m i pi m i rii i cf hrs dz dt 1 1 . …(2) the ergun equation was used for computing total differential pressure drop in axial flow reactor [15] : g de me g de e dz dp pp t 23 2 32 3 5 )1( 10*5.1 1 10*75.1       …(3) in order to evaluate the heat capacity the following correlation was used [16] ; 3 i 2 iiii tdtctbacp  …(4) the effect of temperature and pressure on the kinetic constants was expressed in equation (5), jenkins et al. 1980 [17] ; …(5) the values of pressure effect factors on reaction rate are given in table (2). table 2, values of pressure effect reaction rate [17] . reactions ak isomerization 0.37 dehydrocyclization -0.7 hydrocracking 0.433 hydrodealkylation 0.5 dehydrogenation 0.0 4. kinetic model in this study, 24 lump kinetic model which proposed by ancheyta et al 2000 [11] was used. according to this model, the naphtha feed to reforming process contain paraffin’s, naphthenes, and aromatics with carbon number from 1 to 11 carbon atoms for paraffin’s (p1-p11) and from 6 to 11 carbon atoms for naphthenes (n6-n11) and aromatics (a6-a11). the extended kinetic model employs a lumped mathematical representation of the seventy-one chemical reactions for all 24 lumps that taken place can be shown in table (3). all reaction steps are combined into twenty-four rate reaction equations (ri), one for each component. each reaction rate equation is a function of the kinetic constant (ki) and the component partial pressure (pi). . table 3, reactions of the kinetic model (ancheyta et al. (2001)). number of reactions paraffin’s naphthenes aromatics pn → nn pn → pn-j + pj subtotal 6 26 32 nn → an nn → nn-j + pj nn → pn subtotal 6 11 7 24 an → an-j + pj an → pn an → nn subtotal 7 5 1 13 total 71 n: number of atoms of carbon (1 ≤ i ≤ 5) ramzy h. saihod al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 4761 (2014) 51 5. optimization optimization can be for minimization or maximization of the desired objective function with respect to decision variables subject to process constraints and bounds on the variables. an optimization problem can have a single optimum or multiple optima, one of which is the global optimum and the others are local optima. a global minimum has the lowest value of the objective function throughout the region of interest. most of the traditional optimization algorithms based on gradient methods have the possibility of getting trapped at local optimum depending upon the degree of non-linearity and initial guess. unfortunately, none of the traditional algorithms are guaranteed to find the global optimum solution. in the recent past, nontraditional search and optimization techniques (evolutionary computation) based in natural phenomenon such as genetic algorithms (gas) has been developed to overcome these problems. arx et al., 1998 [19] used genetic algorithm technique for finding a global minimum for the error function. tongcheng et al., 2005 [20] combine numeric genetic algorithm (nga) and tabu search (ts) to optimize the estimated rate constants of a consecutive reaction. zhao et al., 2006 [21] used a nonlinear least squares regression to fit the kinetic profiles. genetic algorithms (gas) are powerful and widely applicable stochastic search and optimization methods based on the concepts of natural selection and natural evaluation. genetic algorithm works on a population of individuals represents candidate solutions to the optimization problem. these individual consists of a strings (called chromosomes) of genes. the genes are a practical allele (gene could be a bit, an integer number, a real value or an alphabet character,…,etc depending on the nature of the problem). gas applying the principles of survival of the fittest , selection , reproduction , crossover (recombining) , and mutation on these individuals to get , hopefully , a new butter individuals (new solutions). genetic algorithm generates new population of chromosomes by selecting the better fit solutions from existing population and applying genetic operators to produce new offspring of the solutions. the process is repeated successively to generate new population iteratively. this process is repeated until some criterion is met or a reasonably acceptable solution is found. the outline of the genetic algorithm is given below [18] . 1. [start] generate random population of n chromosomes (suitable solutions for the problem). 2. [fitness] evaluate the fitness f(x) of each chromosome x in the population. 3. [new population] create a new population by repeating following steps until the new population is complete. i. [selection] select two parent chromosomes from a population according to their fitness (the better fitness, the bigger chance to be selected). ii. [crossover] with a crossover probability cross over the parents to form a new offspring (children). if no crossover was performed, offspring is an exact copy of parents. iii. [mutation] with a mutation probability mutate new offspring at each locus (position in chromosome). iv. [accepting] place new offspring in a new population 4. [replace] use new generated population for a further run of algorithm 5. [test] if the end condition is satisfied, stops, and returns the best solution in current population 6. [loop] go to step 2 proportional selection, ranking, and tournament selection are the most popular selection procedures. table 4, contains the parameters of genetic algorithm. population size 10 maximum generation 3000 crossover probability 0.8 mutation probability 0.05 neighborhood size 0.05 6. numerical computation for each individual reactor within the process, numerical integration method was used to integrate the component mass balance, energy balance and pressure drop differential equations (1, 2 and 3) to obtain concentration, temperature and pressure profiles along the reactor as follows. the rate equations (system of simultaneous differential equations) of the reaction were solved to get the analytical concentration versus reactor length profiles. ramzy h. saihod al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 4761 (2014) 52 fourth order runge-kutta integration command named ode45 was used to integrate 24 stiff ordinary differential equations for mass balance and two other equations for heat balance and pressure drop. genetic algorithm was used to predict the parameters of kinetic model by minimizing the objective function j in equation 6, which is the sum of squares of errors between the predicted and measured values for all of the state variables.               nr i nc j i i pred i ji pred ji t tt yy n j 1 1 2 exp exp 2exp ,, exp )()( 1 …(6) where: exp , jiy is the composition of component j for the effluent stream of reactor no i. using the differential optimization algorithm to optimize the system through a sequence of optimization-evaluation, the objective function [eq. (6)] was minimized and the global optimum set of kinetic parameters was found out. it is important to mention here that [eq. (6)] was used in evaluation the fitness (objective function) for each chromosome x in the population. values of the frequency factors (a1, a2 to a71), activation energies (e1, e2 to e71) were found by minimization of the sum of the squares of the deviations between the plant and the calculated results of the key variables (the compositions and temperature of effluent from each one of the four reactors). the fitness for each generation of chromosomes was calculated and the minimum fitness represents the best chromosomes within the chromosomes and the average fitness was also calculated. figure (2) shows a plot of the best and mean fitness (j) with respect to generation number. genetic algorithm has one disadvantage which is a huge computation time in the case of complex systems. in the present case study a pc with 4.12 ghz and 4gb ram. 5 runs take more than 120 hr to reach produced results. finally the better chromosomes was selected which represent less objective function for all chromosomes and all generations. the kinetic parameters of obtained reaction rate with the genetic optimization procedure are presented in the table 5. 0 500 1000 1500 2000 2500 3000 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 generation f it n e ss , j minimum fitness mean fitness fig. 2. minimum and mean fitness with respect to generation number. 7. results and discussion 7.1. validation of reaction kinetics to validate the predicted kinetic model, the model results using the predictive kinetic model were compared with actual results collected from al-doura refinery (catalytic reforming process). figure 3 (a, and b) shows the comparison between the actual and simulated reformate composition (run 1 means the data collected in 1/12/2012, while run 2 in 1/1/2012). it can be observed that the calculated reformate compositions of all (paraffins , naphthenes, and aromatics) for the four reactors in catalytic reforming unit agree very well with experimental information with average deviation less than 2% as shown in table (6 and 7). . . ramzy h. saihod al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 4761 (2014) 53 table 5, kinetic constants of the kinetic model. reaction step ko ea (cal/mol) reaction step ko ea (cal/mol) reaction step ko ea (cal/mol) p11 n11 0.073082 53553.8 p8 2p4 0.001478 65074.0 n8 n7+p1 0.000016 27622.9 p10 n10 0.037751 37965.0 p7 p6+p1 0.000704 58826.6 n11 a11 1.146035 24527.0 p9 n9 0.055255 9439.8 p7 p5+p2 0.003188 39451.4 n10 a10 0.903828 23982.5 p8 n8 0.033905 53951.7 p7 p4+p3 0.000376 65101.8 n9 a9 0.403788 6489.7 p7 n7 0.004895 39023.9 p6 p5+p1 0.003237 19289.4 n8 a8 0.395175 29318.6 p6 n6 0.000004 41629.3 p6 p4+p2 0.000070 64572.5 n7 a7 0.286847 31262.2 p11 mcp 0.009867 36845.6 p6 2p5 0.007834 11940.1 n6 a6 0.090934 33819.9 p11 p10+p1 0.055585 33531.3 p5 p4+p1 0.000668 60910.7 a11 p11 0.014602 13735.3 p11 p9+p2 0.070800 29879.0 p8 p3+p2 0.020922 14733.7 a10 p10 0.014531 11859.7 p11 p8+p3 0.090772 22115.8 n11 p11 0.033542 16723.6 a9 p9 0.015793 11816.5 p11 p7+p4 0.013195 58984.6 n10 p10 0.047576 47431.2 a8 p8 0.010064 9059.9 p11 p6+p5 0.057271 63624.4 n9 p9 0.051031 35413.1 a7 p7 0.001665 27438.8 p10 p9+p1 0.003473 27543.6 n8 p8 0.024635 12039.8 a11 a10+p1 0.002544 21381.4 p10 p8+p2 0.000517 39959.3 n7 p7 0.009329 11474.4 a11 a9+p2 0.005768 37776.0 p10 p7+p3 0.001024 61173.5 n6 p6 0.195584 17660.9 a10 a9+p1 0.003530 43959.9 p10 p6+p4 0.000822 64218.0 mcp p6 0.001872 35936.4 a10 a8+p2 0.000541 40180.9 p10 2p5 0.000389 62410.0 n11 n10+p1 0.082099 58751.5 a10 a7+p3 0.000005 40148.4 p9 p8+p1 0.008461 16828.6 n11 n9+p2 0.114900 24140.5 a9 a8+p1 0.001916 39779.4 p9 p7+p2 0.000367 61631.1 n11 n8+p3 0.066425 18506.9 a9 a7+p2 0.001371 42474.0 p9 p6+p3 0.001029 61813.5 n10 n9+p1 0.131747 15698.4 a8 a7+p1 0.000059 32571.2 p9 p5+p4 0.000012 48938.2 n10 n8+p2 0.087315 46817.6 a6 n6 0.013302 24076.0 p8 p7+p1 0.000228 60915.0 n10 n7+p3 0.001255 38799.8 mcp n6 0.234651 36084.8 p8 p6+p2 0.015421 64298.5 n9 n8+p1 0.056925 64391.1 n6 mcp 0.014943 24377.5 p8 p5+p3 0.000375 29372.1 n9 n7+p2 0.002137 61898.0 ramzy h. saihod al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 4761 (2014) 54 table 6, comparison between actual and simulated reformate compositions (run 1). composition feed reactor 1 reactor 2 reactor 3 reactor 4 exp. pred. abs. diff. exp. pred. abs. diff. exp. pred. abs. diff. exp. pred. abs. diff. n-p4 0.0036 0.0023 0.0000 0.0023 0.0014 0.0000 0.0014 0.0026 0.0000 0.0026 0.0014 0.0000 0.0014 n-p5 0.0106 0.0128 0.0130 0.0002 0.0135 0.0192 0.0057 0.0200 0.0242 0.0042 0.0177 0.0278 0.0101 n-p6 0.0802 0.0797 0.0890 0.0093 0.0879 0.0936 0.0057 0.0969 0.0962 0.0007 0.0908 0.0955 0.0047 n-p7 0.1243 0.1201 0.1242 0.0041 0.1139 0.1162 0.0023 0.1040 0.1062 0.0022 0.0894 0.0945 0.0051 n-p8 0.1023 0.1194 0.1156 0.0038 0.1003 0.0980 0.0023 0.0756 0.0748 0.0008 0.0548 0.0597 0.0049 n-p9 0.1782 0.1130 0.1191 0.0061 0.0913 0.0682 0.0231 0.0666 0.0510 0.0156 0.0452 0.0432 0.0020 n-p10 0.1214 0.0928 0.1107 0.0179 0.0754 0.0756 0.0002 0.0569 0.0513 0.0056 0.0424 0.0364 0.0060 n-p11 0.0020 0.0040 0.0009 0.0031 0.0043 0.0001 0.0042 0.0064 0.0000 0.0064 0.0063 0.0000 0.0063 mcp 0.0033 0.0021 0.0047 0.0026 0.0005 0.0049 0.0044 0.0005 0.0050 0.0045 0.0036 0.0052 0.0016 n6 0.0214 0.0000 0.0055 0.0055 0.0000 0.0034 0.0034 0.0000 0.0041 0.0041 0.0000 0.0047 0.0047 n7 0.0554 0.0046 0.0160 0.0114 0.0035 0.0021 0.0014 0.0036 0.0019 0.0017 0.0032 0.0017 0.0015 n8 0.0699 0.0078 0.0141 0.0063 0.0076 0.0070 0.0006 0.0072 0.0065 0.0007 0.0055 0.0056 0.0001 n9 0.0406 0.0183 0.0169 0.0014 0.0152 0.0090 0.0062 0.0098 0.0063 0.0035 0.0055 0.0052 0.0003 n10 0.0542 0.0000 0.0022 0.0022 0.0000 0.0022 0.0022 0.0000 0.0016 0.0016 0.0000 0.0012 0.0012 n11 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 a6 0.0035 0.0080 0.0078 0.0002 0.0106 0.0114 0.0008 0.0135 0.0155 0.0020 0.0161 0.0215 0.0054 a7 0.0255 0.0632 0.0664 0.0032 0.0812 0.0907 0.0095 0.1001 0.1053 0.0052 0.1215 0.1238 0.0023 a8 0.0762 0.1379 0.1338 0.0041 0.1707 0.1705 0.0002 0.2059 0.2027 0.0032 0.2478 0.2305 0.0173 a9 0.0182 0.1427 0.1030 0.0396 0.1485 0.1514 0.0029 0.1536 0.1611 0.0075 0.1659 0.1572 0.0087 a10 0.0091 0.0713 0.0570 0.0143 0.0742 0.0763 0.0021 0.0768 0.0860 0.0092 0.0829 0.0861 0.0032 a11 0.0000 0.0000 0.0002 0.0002 0.0000 0.0003 0.0003 0.0000 0.0003 0.0003 0.0000 0.0002 0.0002 para ffins 0.623 0.544 0.574 0.030 0.488 0.476 0.012 0.429 0.413 0.016 0.348 0.371 0.023 naph thenes 0.245 0.033 0.059 0.026 0.027 0.028 0.002 0.021 0.025 0.004 0.018 0.023 0.005 arom atics 0.132 0.423 0.366 0.057 0.485 0.496 0.011 0.550 0.562 0.012 0.634 0.606 0.028 temp. (k) 743.150 698.150 697.454 0.696 732.150 729.251 2.899 738.150 738.414 0.264 745.150 742.418 2.732 ramzy h. saihod al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 4761 (2014) 55 table 7, comparison between actual and simulated reformate compositions (run 2). composition feed reactor 1 reactor 2 reactor 3 reactor 4 exp. pred. abs. diff. exp. pred. abs. diff. exp. pred. abs. diff. exp. pred. abs. diff. n-p4 0.0025 0.0021 0.0000 0.0021 0.0025 0.0000 0.0025 0.0033 0.0000 0.0033 0.0036 0.0000 0.0036 n-p5 0.0059 0.0097 0.0080 0.0017 0.0150 0.0138 0.0012 0.0223 0.0189 0.0034 0.0257 0.0229 0.0028 n-p6 0.0378 0.0462 0.0492 0.0030 0.0590 0.0618 0.0028 0.0753 0.0718 0.0035 0.0782 0.0778 0.0004 n-p7 0.1225 0.1110 0.1219 0.0109 0.1016 0.1134 0.0118 0.1046 0.1030 0.0016 0.0983 0.0911 0.0072 n-p8 0.1182 0.1375 0.1327 0.0048 0.1058 0.1121 0.0063 0.0877 0.0843 0.0034 0.0733 0.0661 0.0072 n-p9 0.2035 0.1196 0.1357 0.0161 0.0851 0.0763 0.0088 0.0683 0.0562 0.0121 0.0500 0.0471 0.0029 n-p10 0.1093 0.1004 0.1012 0.0008 0.0766 0.0704 0.0062 0.0596 0.0483 0.0113 0.0484 0.0343 0.0141 n-p11 0.0016 0.0030 0.0007 0.0023 0.0034 0.0001 0.0033 0.0049 0.0000 0.0049 0.0053 0.0000 0.0053 mcp 0.0009 0.0009 0.0023 0.0014 0.0015 0.0031 0.0016 0.0023 0.0036 0.0013 0.0026 0.0042 0.0016 n6 0.0199 0.0000 0.0046 0.0046 0.0000 0.0021 0.0021 0.0000 0.0029 0.0029 0.0000 0.0036 0.0036 n7 0.0507 0.0042 0.0156 0.0114 0.0035 0.0021 0.0014 0.0037 0.0019 0.0018 0.0034 0.0017 0.0017 n8 0.0793 0.0085 0.0168 0.0083 0.0088 0.0078 0.0010 0.0083 0.0072 0.0011 0.0072 0.0061 0.0011 n9 0.0469 0.0363 0.0191 0.0172 0.0268 0.0100 0.0168 0.0201 0.0069 0.0132 0.0152 0.0056 0.0096 n10 0.0588 0.0000 0.0020 0.0020 0.0000 0.0020 0.0020 0.0000 0.0015 0.0015 0.0000 0.0012 0.0012 n11 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 a6 0.0017 0.0046 0.0054 0.0008 0.0075 0.0077 0.0002 0.0102 0.0103 0.0001 0.0119 0.0149 0.0030 a7 0.0244 0.0547 0.0607 0.0060 0.0789 0.0842 0.0053 0.0946 0.0985 0.0039 0.1064 0.1165 0.0101 a8 0.0858 0.1473 0.1487 0.0014 0.1911 0.1890 0.0021 0.2110 0.2238 0.0128 0.2323 0.2530 0.0207 a9 0.0200 0.1427 0.1158 0.0269 0.1553 0.1691 0.0138 0.1492 0.1782 0.0290 0.1588 0.1720 0.0132 a10 0.0100 0.0713 0.0594 0.0119 0.0776 0.0748 0.0028 0.0746 0.0824 0.0078 0.0794 0.0816 0.0022 a11 0.0000 0.0000 0.0001 0.0001 0.0000 0.0003 0.0003 0.0000 0.0002 0.0002 0.0000 0.0002 0.0002 para ffins 0.601 0.530 0.551 0.022 0.449 0.453 0.004 0.426 0.391 0.035 0.383 0.353 0.029 naph thenes 0.257 0.050 0.060 0.010 0.041 0.027 0.014 0.034 0.024 0.011 0.028 0.022 0.006 aro atics 0.142 0.421 0.389 0.032 0.510 0.521 0.010 0.540 0.585 0.045 0.589 0.625 0.036 temp. (k) 743.15 698.15 694.69 3.456 732.15 728.49 3.660 738.15 738.22 0.078 745.150 742.442 2.708 ramzy h. saihod al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 4761 (2014) 56 0 0.05 0.1 0.15 0.2 0 0.05 0.1 0.15 0.2 experimental mole fraction k in e ti c m o d e l m o le f ra c ti o n reactor 1 reactor 2 reactor 3 reactor 4 0 0.05 0.1 0.15 0.2 0 0.05 0.1 0.15 0.2 experimental mole fraction k in e ti c m o d e l m o le f ra c ti o n reactor 1 reactor 2 reactor 3 reactor 4 0 2000 4000 6000 8000 10000 12000 14000 16000 18000 690 700 710 720 730 740 750 catalyst weight (kg) t em p er at u re ( k ) 0 2000 4000 6000 8000 10000 12000 14000 16000 18000 690 700 710 720 730 740 750 catalyst weight (kg) t em p er at u re ( k ) a (run 1) b (run 2) fig. 3. comparison between actual and simulated reformate compositions (symbols actual ,lines predicted). 7.2. reactor temperature simulation results the temperature decreases along the catalyst bed in the reactors of reforming process, because the process reactions are, overall, endothermic. for this reason, commercial catalytic reformers are designed with multiple reactors and with heaters between the reactors to maintain reaction temperature at operable levels. the simulated temperature profile with the actual reactors temperature is plotted in figure (4), it can be seen that in the first reactor the temperature decrease very sharp, since the major reactions are endothermic and very fast reaction, such as dehydrogenation of naphthenes components to aromatics and the temperature decreasing drop is less in other reactors especially in the last two reactors, which is due to the exothermic hydrocracking reaction. the comparison between the simulated temperature and the actual temperature of commercial reforming unit shown in table (6 and 7), which shows a good agreement results and the accumulated difference is 6.5 ° c between the predicted and actual reactors temperature. . figure (5) shows both the actual and the simulated pressure drop with respect to accumulative catalyst weight within the four reactors in commercial reforming process, it can be seen that a good agreement between these results. a (run 1) b (run 2) fig. 4. comparison between actual and simulated temperature profile (symbols actual, lines predicted). ramzy h. saihod al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 4761 (2014) 57 0 2000 4000 6000 8000 10000 12000 14000 16000 18000 0 0.05 0.1 0.15 0.2 catalyst weight (kg) m o le f ra ct io n p 4 p 5 p 6 p 7 p 8 p 9 p 10 0 2000 4000 6000 8000 10000 12000 14000 16000 18000 0 0.05 0.1 0.15 0.2 0.25 catalyst weight (kg) m o le f ra ct io n p 4 p 5 p 6 p 7 p 8 p 9 p 10 0 2000 4000 6000 8000 10000 12000 14000 16000 18000 2.2 2.3 2.4 2.5 2.6 2.7 2.8 x 10 6 catalyst weight (kg) p re ss u re ( p a) 0 2000 4000 6000 8000 10000 12000 14000 16000 18000 2.2 2.3 2.4 2.5 2.6 2.7 2.8 x 10 6 catalyst weight (kg) p re ss u re ( p a) 0 2000 4000 6000 8000 10000 12000 14000 16000 18000 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 catalyst weight (kg) r ef o rm at e c o m p o si ti o n m o l% paraffins naphthenes aromatics 0 2000 4000 6000 8000 10000 12000 14000 16000 18000 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 catalyst weight (kg) r ef o rm at e c o m p o si ti o n m o l% paraffins naphthenes aromatics a (run 1) b (run 2) fig. 5.comparison between actual and simulated pressure drop (symbols actual ,lines predicted) 7.3. reformate composition simulation results reformate composition of total paraffins, naphthenes, and aromatics obtained from actual catalytic reforming unit with the proposed model are shown in figure (6), the results show a good agreement between the actual and the simulated results. tables (6 and 7) show comparison between the actual and the simulated reformate compassion of all paraffins components (4 – 11) carbon number, naphthenes and aromatics components from (6 – 11) carbon number through the four reactors in catalytic reforming process. it can be observed that total aromatics hydrocarbons yields are higher as goes from the first reactor to the last reactor, therefore the total amount of aromatics increase from 13.2 mol% to reach 42.3%, 48.5%, 55%, and 63.4% for feedstock of run 1. while for feedstock of run 2 increasing from 14.2 mol% to 42.1%, 51%, 54%, and 58.9%. a (run 1) b (run 2) fig. 6. comparison between actual and simulated total paraffins, naphthenes, and aromatics in reforming process (symbols actual ,lines predicted). figure (7) shows a comparison between the actual and the simulated results of the heavy and the light paraffins along the reactor as a function of catalyst weight. it can be seen that light paraffins increased because they are produced by hydrocracking reaction, while heavy ramzy h. saihod al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 4761 (2014) 58 0 2000 4000 6000 8000 10000 12000 14000 16000 18000 0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 catalyst weight (kg) m o le f ra ct io n mcp n 6 n 7 n 8 n 9 n 10 n 11 0 2000 4000 6000 8000 10000 12000 14000 16000 18000 0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 catalyst weight (kg) m o le f ra ct io n mcp n 6 n 7 n 8 n 9 n 10 n 11 0 2000 4000 6000 8000 10000 12000 14000 16000 18000 0 0.05 0.1 0.15 0.2 catalyst weight (kg) m o le f ra ct io n p 4 p 5 p 6 p 7 p 8 p 9 p 10 0 2000 4000 6000 8000 10000 12000 14000 16000 18000 0 0.05 0.1 0.15 0.2 0.25 catalyst weight (kg) m o le f ra ct io n p 4 p 5 p 6 p 7 p 8 p 9 p 10 paraffins decreasing because exhibited high levels of conversion this is because the increase in the probility of ring formation is high as the molecular weight of paraffins increases also in the last two reactors since dehydrocyclization and reaction take place. a (run 1) b (run 2) fig. 7. comparison between actual and simulated paraffins composition (symbols actual, lines predicted). the naphthenes and aromatics reformate comparison results shown in figures (8, and 9). naphthenes components which are the most desirable in reforming feed stocks react and converted to aromatics components through dehydrogenation reaction which take place in the first two reactors and these reactions goes to completion. also it is important to mention her that all aromatics comparison in reformate are increased as feedstock passes through the catalytic reforming reactors especially lighter aromatics (a6, a7, a8, and a9), while heavy aromatics (a10, and a11) increasing very low or nearly remains unchanged. . a (run 1) b (run 2) fig. 8. comparison between actual and simulated naphthenes composition (symbols actual, lines predicted). ramzy h. saihod al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 4761 (2014) 59 0 2000 4000 6000 8000 10000 12000 14000 16000 18000 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 catalyst weight (kg) m o le f ra ct io n a 6 a 7 a 8 a 9 a 10 a 11 0 2000 4000 6000 8000 10000 12000 14000 16000 18000 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 catalyst weight (kg) m o le f ra ct io n a 6 a 7 a 8 a 9 a 10 a 11 a (run 1) b (run 2) fig. 9. comparison between actual and simulated aromatics composition (symbols actual ,lines predicted). 8. conclusions the kinetic parameters of model are based on the steady state condition and are obtained from a commercial plant data furnished by a domestic petroleum refinery. in this work a mathematical model of semi-regenerative catalytic reforming unit with four reactors in series it has been developed. the model parameters were estimated on the basis of data obtained from industrial unit (al-dura refinery). the effects of different feed composition on product properties are evaluated, and simulation results were compared with the actual data, there for the absolute percentage error of aromatics compositions range between (2% to 8.3%) and the temperature absolute percentage error range between (0.01% to 0.5%) for four reactors respectively. nomenclature a aromatics ( ) n naphthene ( ) p paraffin ( ) mcp methylcyclopentane ( ) n-p normal paraffin ( ) ki reaction rate constant hr -1 k ◦ i pre-exponential factor ( ) ea activation energy kcal/mole r gas constant j/mole.k t reaction temperature °c t • initial temperature °c pt total pressure bar p◦ partial pressure bar αk pressure effect ( ) ci cp concentration of species i specific heat mole/cm 3 j/mole.k z, z length of reactor cm m.wt molecular weight g/gmole whs v weight hour space velocity hr -1 ri reaction rate of species i mole/gcat. hr s cross sectional area of reactor m 2 ∆h˚r heat of i th reaction j/ mole fn molar flow rate of species n mole/hr cp specific heat j/mole.°c dp equivalent diameter of a catalyst particle m e void fraction of reactor bed m 3 /m 3 m viscosity pa.s g total mass flux of fluid kg.s/m 2  density kg/m 3 ramzy h. saihod al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 4761 (2014) 60 9. references [1] askari a., karimi h., rahimi m.r., ghanbari m., "simulation and modeling of catalytic reforming process", j. petroleum and coal, vol 54, no (1), p 76-84, 2012. [2] seif mohaddecy s.r., zahedi s., sadighi s., bonyad h.," reactor modeling and simulation of catalytic reforming process", j. petroleum and coal, vol 48, no (3), p 28-35, 2006. [3] yong h., hongy s., jian c.,” modeling, simulation and optimization of commercial naphtha catalytic reforming process ”, proceeding of the 42nd ieee conf, usa, (dec), p 6206, 2003. [4] jin l., tan y., liangcai l.,” modeling and optimization of semi-regenerative catalytic reformer”, proceeding of the 2005 ieee conf, canada, (aug), p 28-31, 2005. [5] smith r.b.,” kinetic analysis of naphtha reforming with platinum catalyst ”, j. chem. eng. prog, vol 55, no6, p 76-80, 1959. [6] krane h.g., croh a.b., schulman b.l., and sinfelt j.h.,” reactions in catalytic reforming of naphtha’s,” 5th world petroleum congress, vol.3, p 39, 1970. [7] kmak w.s.,”a kinetic simulation model of the powerforming process ”, aiche, meeting, houston tx, 1972. [8] marin g.b., froment g.f.,” reforming of c6 hydrocarbons on pt-al2o3 catalyst ”, j. chem. eng. sci, vol 37, no 5, p 759-773, 1982. [9] ramage m.p., graziani k.r., krambeck f.j., choi b.c.,” mobils reforming model: a review of mobil’s industrial process modeling philosophy ”,j. chem. eng. sci, vol 35, p 193-266, 1987. [10] taskar u.m., riggs j.b.,” modeling and optimization of a semiregenerative catalytic naphtha reformer ”, aiche. j, vol 43, no 3, p 740-753, 1997. [11] ancheyta j.j., eduardo v.m., “ kinetic modeling of naphtha catalytic reforming reactions ”, j. energy fuels, vol 14, no 5, p 1032-1037, 2000. [12] weifeng h., young h., hongye s., jain c.,” simulation, sensitivity analysis and optimization of a continuous catalytic reforming process ”, proceeding of the 5th world congress on intelligent control and automation, june (15-19), 2004. [13] arani h.m., shokri s., shirvani m., " dynamic modeling and simulation of catalytic naphtha reforming", j. chem eng and appl, vol 1, no (1), august 2010. [14] villafertre e., jorge a.j.,” kinetic and reactor modeling of naphtha reforming process ”, j. petroleum and coal, vol 44, 1-2, p 63-66, 2002 [15] froment g.f., bischoff k.b.,”chemical reactor analysis and design”, john wiley and sons, 1990. [16] reid r.c., prausnitz j.m., sherwood t.k.,” the properties of gases and liquid”, 3rd edition, mcgraw-hill co, 1977. [17] jenkins j.h., stephens t.w.,” kinetics of catalytic reforming”, j. hyd. proc, nov, p 163-167, 1980. [18] namita k., anju r., akshatha.p.s,”genetic algorithm: a search of complex spaces” international journal of computer applications (0975 – 8887), volume 25– no.7, july 2011. [19] arx, k.b.v., j.j. manock, w.h. scott and m. messina, 1998. “using limited concentration data for the determination of rate constants with the genetic algorithm” environ. sci. technol., 32: 3207-3212, (1998). [20] tongcheng, c., z. zhongliang, h. xiaofeng and l. tonghua, 2005”simultaneous determination of reaction order and rate constant of consecutive reactions by union optimization algorithm of nga-ts” can. j. anal. sci. spectros., 50: 182-191, (2005). [21] zhao, y., g. wang, w. li and z.l. zhu,”determination of reaction mechanism and rate constants of alkaline hydrolysis of phenyl benzoate in ethanol water medium by nonlinear least squares regression” chemometr. intell. laborat. syst., 82: 193-199, (2006). (2014) 4761، صفحة 1العدد، 10دمجلة الخوارزمي الهندسية المجل رمزي صهيود حميد 61 تفاعالت تهذيب النفثا الثقيلة لوحدة حركيةاستخدام النظرية الجينية إليجاد مصفى الدورة ***عباس عالء جواد **زيدون محسن شكور *رمزي صيهود حميد الجامعة التكنولوجية / قسم تكنولوجيا النفط* الجامعة التكنولوجية / م الهندسة الكيمياويةقس ** طشركة مصافي الوس/ مصفى الدورة *** ramze_eng@yahoo.com : االلكتروني البريد* dr_zaidoon@yahoo.com : ونيااللكتر البريد** ahmed_198494@yahoo.com : االلكتروني البريد*** الخالصة وحدة التهذيب تتكون من . تفاعالت وحدة تهذيب النفثا الموجودة في مصفى الدورة ببغدادحركية في هذا البحث تم استخدام النظرية الجينية إليجاد الموديل الرياضي . تم تطوير موديل رياضي لمحاكاة عملية التهذيب ذاتية التنشيط للنفثا في الحالة المستقرة ولبعد واحد. مفاعالت على التوالي اربع .يصف تغير التراكيز والضغط ودرجة الحرارة على طول المفاعالت االربعة المستخدمة لعملية التهذيب االيزو )مادة وهي البرافينات 42التفاعالت التي تتضمن وصف حركيةتجميع نتائج عملية بظروف مختلفة وتم استخدامها لوصف ثوابت تم 11من حركيةذرة كاربون باالعتماد على 11-6ذرة كاربون والنفثينات والمواد االروماتية التي تحتوي من 11الى 1التي تحتوي من( والنورمال مادة وكذلك درجة الحرارة لتيار التدفق لكل مفاعل من المفاعالت االربعة المستخدمة ضمن عملية 41لداخل لالختيار االفضل هو التركيب ل ا .تفاعل تيار واستخدمت النظرية التفاضلية لالخ ,تفاعل ضمن عملية التهذيب 11ثابت للموديل الرياضي المحسوبة المتكونة من 124التهذيب بينما الخارج هو .االفضل لحساب ثوابت الموديل الرياضي بنفس ماخوذة عملية نتائج مع المقترحة التفاعل حركية على المعتمد الرياضي الموديل من المستحصلة الرياضية النتائج مقارنة تم تصف المقترحة التفاعل ةحركي ان على يدل العملية وهذا والنتائج الرياضي الموديل نتائج بين جيدجدا انطباق هناك كان حيث الظروف والنسبة (and 6.1% ,8.3 ,2 ,7.5) العطرية للمواد للخظأ المطلقة المئوية النسبة وكانت النفثا تهذيب وحدة في التفاعالت جيد بشكل .التوالي على االربعة للمفاعالت( (and 0.3% ,0.01 ,0.5 ,0.49 هي الحرارة لدرجة للخطأ المئوية mailto:ramze_eng@yahoo.com*البريد mailto:ramze_eng@yahoo.com*البريد mailto:dr_zaidoon@yahoo.com**البريد mailto:dr_zaidoon@yahoo.com**البريد mailto:ahmed_198494@yahoo.com***البريد mailto:ahmed_198494@yahoo.com***البريد (2014) 4761، صفحة 1العدد، 10دمجلة الخوارزمي الهندسية المجل رمزي صهيود حميد 64 <4d6963726f736f667420576f7264202d20cce4c7e420e6e6d3c7e320e6c8e5c7c13134392d20313535> al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 14, no. 3, september, (2018) p.p. 149155 bone defect animal model for hybrid polymer matrix nano composite as bone substitute biomaterials jenan s. kashan* wisam k. hamdan ** baha fakhri *** *,** department of biomedical engineering/ university of technology/baghdad/ iraq *** college of veterinary medicine/ university of baghdad/ baghdad/ iraq *email: 70010@uotechnology.edu.iq (received 26 october 2017; accepted 4 march 2018) https://doi.org/10.22153/kej.2018.03.004 abstract addition of bioactive materials such as titanium oxide (tio2), and incorporation of bio inert ceramic such as alumina (al2o3), into polyetheretherketone (peek) has been adopted as an effective approach to improve bone-implant interfaces. in this paper, hot pressing technique has been adopted as a production method. this technique gave a homogenous distribution of the additive materials in the proposed composite biomaterial. different compositions and compounding temperatures have been applied to all samples. mechanical properties and animal model have been studied in all different production conditions. the results of these new tio2/al2o3/peek biocomposites with different compositions were promising, mechanical properties within the range of human cortical bone, suitable for load bearing applications. at the same time, in vivo test shows no inflammation reaction with implanted samples. sustained viability in contact with the sample over seven-day period, showed evidence of excellent biocompatibility in injured rejoins. keywords: histology analysis, hot pressing, mechanical properties, polyetheretherketone (peek), tio2/al2o3/peek biocomposites. 1. introduction defects in bones, can arise duo to human such as, trauma, infection, tumors, or bone damages. most therapies for bone defects are based, on autografts or allografts. [1] many investigations were taken place, to develop biomaterial systems which can be used to repair or replace, natural bone just in case of complicated fracture, previous folks suffer from accidently, fractures, and bone cancer patients [2] at present, bone grafts and replacement, poses challenge to develop biomaterials for scaffold applications" this might be achieved via any of either, endogenous or exogenous materials: auto graft, allograft or a xenograft" [3] any proposed biomaterial system for such application, should possess biocompatibility, less inflammation effect, and suitable mechanical properties that should be very close to, natural bone properties to avoid stress shielding, effect which take place when the modulus of elasticity, for biomaterial exceeds that of natural tissue, [ 4] poly (ether-ether-ketone) (peek) is considering a semi-crystalline, thermoplastic with excellent biocompatibility (fibroblasts and osteoblasts), and as very suitable mechanical properties (strength, stiffness), and superior thermal stability. modulus of elasticity for peek is similar to that of cortical bone, which can reduce stress shielding following implantation. it is also, radiolucent which permits radiographic assessment. the combination of these optimal, properties has made peek of great potential for orthopedic application [ 5] all previous studies suggest that the n-tio2 composites have high biocompatibility because of the excellent bioactivity of tio2 nanoparticles in composites and the morphological properties for the tio2 particles [6] jenan s. kashan al-khwarizmi engineering journal, vol. 14, no. 3, p.p.149155 (2018) 150 it is believed that tio2 nanoparticles have higher bioactivity, than conventional (micron) particle sizes. when exposed to nano phase tio2 particles, osteoblasts and chondrocytes show a well spread. [7,8] hence, ceramic oxides or metallic dispersions are introduced as reinforcing agent. among the ceramic reinforcement, alphaal2o3 has been utilized in orthopedically application because of its glorious wear resistance, [ 9] one of the most important issues to be considered, in suggested biomaterials for bone autograft and allograft is their mechanical, properties and their distribution within prepared biomaterial. in vitro and in vivo testing must take place in order to determine whether a newly developed implant material conforms to the requirements of biocompatibility, mechanical stability and safety. in vitro test results can be difficult to extrapolate, to the invivo situation. for this reason the use of animal models is often an essential step in the testing of orthopedic and dental implants. [10-12] in the present study, tio2/peek nano composites were synthesized for orthopedic application. alumina used in nano size to modify mechanical properties for implants. mechanical properties evaluation has been applied to evaluate implants rather than direct implantation using animal model. histology path used to analyze biocompatibility and inflammation effect for implants within host tissue environment. [13] 2. materials and methods 2.1 materials peek powder have an average particle size of 10µm,, with a nominal density of 1.3 g/cm3 supplied by right fortune industrial, limited (shanghai, china) were used as polymeric matrix.tio2 and al2o3 were used as ceramic fillers, tio2 (99% pure) having 40 nm average particle size and a 4.23 g/cm3 particle density , while α-alumina powder has an average, particle size of 10nm and a density of (3.890 g/cm3 ). both ceramic powders were supplied by m.k. nano (toronto, canada). 2.2 preparationof ntio2/al2o3/ peek composite a process involving mixing and hot pressing molding were used to prepare the composite samples containing 10 vol%tio2/peek,20vol% tio2/peek, 10 vol% tio2/5 vol% al203/peek, and 20 vol% tio2/5 vol% al2o3/peek. the peek, ntio2, and n al2o3 powders were mixed in high-speed vibrating ball mill at a mixing speed of 500 rpm for 1 hour. hot pressing technique was used to prepare samples with 80 mpa compression pressure at different compounding temperatures, (370,380,390, and400c°). 2.3. mechanical properties the mechanical properties for all samples have been measured by instron material testing machine at0.1 mm⋅min-1 speed. the optimal filler content has been determined by evaluating the mechanical properties of the ntio2/al2o3/peek composites with different filler contents, which was 20 vol% tio2/5 vol% al2o3/peek, all other experaments were done depending on optimal composition. 2.4. animals model eight male (albino rabbits) having a weight of (2.8-3.2 kilograms) and have an ages ranging between sixteen to twenty weeks have been used. a circular defects with a diameter of eight millimeter were made in each animal limb, the rabits were divided into four groups and an empty control group. the animals were sacrificed after different periods (2,4,6, and 8weeks) after surgery. the rabbits head were hair removed and disinfected (by using povidone iodine) prior to local anaesthetic, injections at the surgical site (using 2.2 ml lidocaine hydrochloride 2% with adrenaline 1:80,000). standardized round defects (4number with8 mm in diameter) were created. the holes were filled with the implants. the flaps were repositioned and sutured. the animals were sacrificed at different periods (2, 4 ,6, or 8 weeks) after surgery. 2.5. histologic processing bones were processed for light –microscope histology to establish their histogenesis by using the histokinate. this processing involve the following steps: 1-dehydration: is the removal of all extractable water by alcohol upgrading starting from 70%, through absolute alcohol (70% ,80% ,90%,and 100%), twice for 2hours each time for each step to improve complete dehydration. jenan s. kashan al-khwarizmi engineering journal, vol. 14, no. 3, p.p.149155 (2018) 151 2-clearing: as a dehydrator is removed, the tissue cleared, becoming translucent by using of xylene twice for 1.5 hour for each time. 3-impergnation: is the complete removal of xyline by substitution of paraffin penetration through the tissue, used twice for 2 hours each time in paraffin bath adjusted on 58c. 4-embedding: the processed tissue was oriented in melted paraffin, which provides affirm medium for keeping intact all parts of the bone tissue when sectioned. 5cutting: serial paraffin sections of 6-8 um were cut by using rotary microtome. 6-staining of histological sections, routine histological stain of harris hematoxylin and eosin stain. 3. results and discussion 3.1 mechanical properties measured mechanical properties for implants as comparison with that of natural bone are listed in table 1. figures 1-3 show the relationship between compounding temperature vs. modulus of elasticity, tensile strength, and compressive strength respectively. results for mechanical properties show very close values with that for natural bone which give great indication about proposed composite, as promising replacement for natural bone especially in case of victims of wore , care bombing,and old aged people in iraq and other countries. these findings indicate also that the effect of stress shielding is very limited here [14,15] which will nominate proposed biomaterial as suitable replacement for damaged natural bone. 3.2 in vivo test results histological path for implants are shown in figures 4-8. these figures show that, the healing process for all surgery places was without any abnormal bleeding or infection. in the same time no inflammation evidence were. very small amount of the formation of new bone was observed in the control group. all defects were naturally filled by the brain tissues as well as, the overlying periosteum. normal growth were noticed in all implants which give strong indication that this biocomposite system can be used significaly in bone repair and replacement. table 1, comparison between measured properties and natural bone density and mechanical properties sp. composition compounding 0temp.c modulus of elasticity (gpa) tensile strength (mpa) compressive strength(mpa) cortical bone(compact) 10-20 131–224 131-205 cancellous bone(trabecular) 10 3000(mpa) 50–100 70-280 /peek2vol%tio 10 370 6 140 156 380 6.8 150 159 390 7 155 163 400 7.4 162 168 /peek2vol% tio 20 370 10 170 182 380 11 176 185 390 12.5 178 189 400 13 180 194 /5vol% 210vol%tio /peek3o2al 370 15 184 203 380 15.7 188 209 390 17 191 212 400 17.3 192 215 /5 220vol%tio /peek3o2vol%al 370 19 210 240 380 19.8 215 243 390 20 218 252 400 21 220 260 jenan s. kashan al-khwarizmi engineering journal, vol. 14, no. 3, p.p.149155 (2018) 152 fig. 1. relationship between compounding temperature and modulus of elasticity for different compositions. fig. 2. relationship between compounding temperature and tensile strength for different compositions . fig. 3. relationship between compounding temperature and compressive strength for different compositions. fig. 4. microphotographs of the control show cartilage ingrowth and fibrous tissue stain with h&e (x 400). fig. 5. microphotographs of the bone 2 weeks after implantation show cartilage ingrowth and fibrous tissue, stain with h&e (x 100). fig. 6. microphotographs of the bone 4 weeks after implantation show normal bone morrow without inflammation, stain with h&e (x100) . jenan s. kashan al-khwarizmi engineering journal, vol. 14, no. 3, p.p.149155 (2018) 153 fig. 7. microphotographs of the bone 4 weeks after implantation inert material show no inflammatory cells, stain with h&e (x100). fig. 8. microphotographs of the bone 8 weeks after implantation inert material show few fibrous tissue and cartilage, stain with h&e (x 400). 4. conclusions from listed results we can conclude that tio2/al2o3/peek composites can be a suitable replacement choice in case of complex fractured bone when natural tissues cannot restore their normal structure,rather than ability to use such a biomaterials in artificial limbs manufacturing because of their superior mechanical and biological properties. best mechanical properties were achieved at 20vol % tio2 / 5 vol % al2o3 / peek. animal model shows very suitable biological response for implanted samples which is a strong indication about biocompatibility for the proposed biocomposite system. 5. references [1] m.vaz, h. canhão, and j. fonseca, bone: a composite natural material, advances in comp. mater. analysis of natural and man-made materials, dr. pavla tesinova (ed.),isbn: 978-953-307-449-8, intech, available from: http://www.intechopen.com/books/ [2] p. fratzl, h.gupta, e.paschalis, and p.roshger, structure and mechanical quality of the collagen-mineral nanocomposite in bone. journal of materials chemistry, vol.14, no.14, pp. 2115-2123, 2004, issn 0959-9428. [3] p.fratzl, and r.weinkamer, nature’s hierarchical materials. progress in materials science, vol.52, no.8, pp. 12631334, 2007. [4] z.fratzl , n.; roschger, p; gourrier, a.; weber, m.; misof, b.; loveridge, n.; reeve, j.; klaushofer, k. & fratzl, l.(2009).combination of nano indentation and quantitative backscattered electron imaging revealed altered bone material properties associated with femoral neck fragility. calcified tissue international, vol.85, no.4, pp. 335-343, 2009. [5] [5] h. wang, t. lu, f. meng, h. zhu, and x. liu, “enhanced osteoblast responses to poly ether ether ketone surfacemodified by water plasma immersion ion implantation,” colloids and surfaces b: biointerfaces, vol. 117, pp. 89–97, 2014. [6] c.-m. han, e.-j. lee, h.-e. kim et al,“the electron beam deposition of titanium on polyetheretherketone (peek) and the resulting enhanced biological properties,” biomaterials, vol. 31, no. 13, pp. 3465– 3470, 2010. [7] k. l.wong, c. t.wong,w. c. liu et al., “mechanical properties and in vitro response of strontium-containing hydroxyapatite/polyetheretherketone composites,” biomaterials, vol. 30, no. 2324, pp. 3810–3817, 2009. [8] x. wu, x. liu, j. wei, j. ma, f. deng, and s. wei, “nanotio2/peek bioactive composite as a bone substitute material: in vitro and in vivo studies,” international journal of nanomedicine, vol. 7, pp. 1215– 1225, 2012. [9] h.-k. tsou, p.-y. hsieh, c.-j. chung, c.h. tang, t.-w. shyr, and j.-l. he, “lowtemperature deposition of anatase tio2 on medical grade polyetheretherketone to jenan s. kashan al-khwarizmi engineering journal, vol. 14, no. 3, p.p.149155 (2018) 154 assist osseous integration,” surface and coatings technology, vol. 204, no. 6-7, pp.1121–1125, 2009. [10] y. zhao, h. m. wong, w. wang etal,“cytocompatibility, sseointegration, and bioactivity of three-dimensional porous and nanostructured network on polyetheretherketone,” biomaterials, vol. 34, no. 37, pp. 9264–9277, 2013. [11] h. garg, g. bedi, and a. garg, “implant surface modifications: a review,” journal of clinical and diagnostic research, vol. 6, no. 2, pp. 319–324, 2012. [12] f. awaja, d. v. bax, s. zhang, n. james, and d. r. mckenzie, “cell adhesion to peek treated by plasma immersion ion implantation and deposition for active medical implants,”plasma processes and polymers, vol. 9, no. 4, pp. 355–362, 2012. [13] a. h. c. poulsson, d. eglin, s. zeiter et al., “osseointegration of machined, injection moulded and oxygen plasma modified peek implants in a sheep model,” biomaterials, vol. 35, no. 12, pp. 3717–3728, 2014. [14] z. novotna, a. reznickova, s. rimpelova,m. vesely, z. kolska, and v. svorcik, “tailoring of peek bioactivity for improved cell interaction: plasma treatment in action,” rsc advances, vol. 5, no. 52, pp. 41428–41436, 2015. [15] d.m.devine, j.hahn, r. g. richards, h. gruner, r. wieling, and s. g.pearce, “coating of carbon fiber-reinforced polyetheretherketone implants with titanium to improve bone apposition,”journal of biomedical materialsresearchb:applied biomaterials, vol. 101, no. 4, pp. 591– 598, 2013. )2018( 149-155، صفحة 3د، العد14دجلة الخوارزمي الهندسية المجلمجنان ستار خشان 155 متعددة ذات اساس من البوليمردراسة معالجة الفشل في العظام باستخدام مادة مركبة نموذج حيواني باستخدام ***بهاء فخري **وسام كاظم حمدان *جنان ستار خشان هندسة الطب الحياتي/ الجامعة التكنولوجية قسم*،** *كلية الطب البيطري/ جامعة بغداد uotechnology.edu.iq@70010 البريد االلكتروني:* الخالصة ً مسلك دان اضافة مواد فعالة حيويا وكذلك خاملة حيويا الى المادة البوليميرية بولي ايثرايثركيتون يع ٌ تكنولوجي ا لتحسين التكامل الخلوي بين االنسجة فعاالً ا ً الحية والمواد الحيوية المزروعة في الجسم. في هذا البحث تم استخدام تقنية الكبس على الساخن النتاج النماذج والتي اعطت توزيع ً متجانس ا للمواد المضافة ا البحث كما تم اجراء ةعلى النماذج من المادة المركبة موضوع في المادة المركبة . تم استخدام تراكيب مختلفة ودرجات حرارة كبس مختلفة للحصول حاكي الخواص الزراعه الحيوية للنماذج في نموذج حيواني للحصول على السلوك البايولوجي للمادة المقترحة. اظهرت النتائج للخواص الميكانيكية انها ت توفيرها فضالً عنينت ان هذه المادة المركبة مناسبة لالستخدام ولم تسبب اي سلوك التهابي الميكانيكية للعظم الطبيعي كما ان الدراسة البايولوجية للنماذج ب .سطوح جيدة للبناء الخلوي مع العظم الطبيعي في منطقة االصابة مما يؤكد التوافقية البايولوجية الجيدة للمادة المقترحة مع الجسم زينب يعقوب al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 8, no.3, pp 75 80 (2012) estimation of volumetric mass transfer coefficient in bioreactor zainab yaquob atiya department of biochemical engineering/ al-khwarizmi college of engineering/ university of baghdad email:zainaatia@yahoo.com (received 16 november 2011; accepted 15 april 2012) abstract this study is concentrated to investigate the effects of aeration and stirring speed on the volumetric mass transfer coefficient (kla). a dynamic technique was used in estimating kla values in order to achieve the aim of this study. this study was done in 10l bioreactor by using two medias: 1. dionized water 2. xanthan solution (1 g /l) moreover, the research covered a comparison between the obtained values of kla. the xanthan solution was used because of its higher viscosity in comparison with water. it behaves similarly to the cultivation medium when organisms are cultivated in a bioreactor. growth of organisms in the reactor leads to a change in the viscosity of the medium which affects the mass transfer. two variables, the effect of air flow rate (3-20 l/min) and the effect of stirring speed (250-700rpm) on kla value were studied. other parameters such as temperature, liquid volume, and stirrer shape and stirrer position were held constant; the results demonstrated an increase in kla – value and mass transfer with increasing stirrer speed. thus at higher speed, better dispersion of the bubbles was obtained. therefore, that increased the surface / volume ratio which increased the mass transfer area i.e. kla value. keywords: dynamic technique, agitation and aeration, hennery’s law constant of oxygen. 1. introduction the main objectives of mixing in fermentation are to disperse the air bubbles, to suspend the microorganisms or animal cells, and to enhance heat and mass transfer in the growth medium. the solubility of oxygen in medium is very low while its demand for growth of aerobic microorganisms is high. for example, when oxygen is provided from air, the typical maximum concentration of oxygen in aqueous solution is on the order of 6 to 8 mg/l. in order to estimate the design parameters for oxygen uptake in a bioreactor, many correlations which can be applicable to wide range of gas-liquid systems in addition to the air –water system could be used. since the oxygen is sparingly soluble gas, the overall mass-transfer coefficient kl is equal to the individual mass-transfer coefficient kl. the main objective in bioreactor design is to maximize the oxygen transfer rate with the minimum power consumption necessary to agitate the fluid on one hand. on the other hand it is necessary to minimize air flow rate. in order to maximize the oxygen absorption rate, the term kla (cl *-cl)] should be maximize. the concentration difference is quite limited to be controlled because the value of cl* is limited by its very low maximum solubility. therefore, the main parameters of interest in design are the mass-transfer coefficient and the interfacial area. table 1 lists the solubility of oxygen at 1atm in water at various temperatures. normally air is used to supply the oxygen demand of bioreactor. the maximum concentration of oxygen in water which is in equilibrium with air cl* at atmospheric pressure is about one fifth of the solubility listed according to hennery’s law, po2 =cl* (h) where po2 is the partial pressure of oxygen and h is hennery’s law constant of oxygen at a certain temperature. mailto:email:zainaatia@yahoo.com zainab yaquob atiya al-khwarizmi engineering journal, vol. 8, no. 3, pp 7580 (2012) 76 table 1, (solubility of oxygen in water equilibrium with pure oxygen at 1atm). (international critical tables.vol.3, p.271) temperature( c) mol o2/l mgo2/ l 0 2.18 69.8 10 1.70 54.5 15 1.54 49.3 20 1.38 44.2 25 1.26 40.3 30 1.16 37.1 35 1.09 34..9 solubility of oxygen in xanthan was taken from table 2, in which the oxygen solubility in different fermentation fluids was listed. ideally, oxygen-transfer rates should be measured in a bioreactor which contains both the nutrient and microorganisms during the actual bioreactor process. it is difficult to carry out such a task due to the complicated nature of the medium and the ever changing rheology during cell growth. a common strategy is to use a synthetic system which approximates bioreactor conditions. table 2, (solubility's of oxygen in different fermentation fluids) c* 103( mol/ℓ ) concentration( g/ℓ ) 1.251 1.223 1.213 1.210 1.218 1.192 1.121 1.013 0.991 0.956 0.889 0.802 10 15 20 25 35 50 100 150 200 300 400 500 gluconic acid 1.242 1.196 1.183 1.148 1.137 1.083 0.983 25 40 50 75.6 100 150 200 citric acid 1.250 1.251 1 5 xanthan 1.266 1.241 1.240 1 10 20 pullulan acontraspum 210, supplied by m / s zschiemmer and black, lahnstein / rhein. bvalues measured at 22.6 ° c zainab yaquob atiya al-khwarizmi engineering journal, vol. 8, no. 3, pp 7580 (2012) 77 2. dynamic technique by using the dynamic technique (taguchi and humphrey, 1966), the kla value for the oxygen transfer during an actual fermentation process with real culture medium and microorganisms can be estimated. this technique is based on the oxygen material balance in an aerated batch fermented while microorganisms are actively growing as ………. 1 …(1) where ro2 is cell respiration rate [g o2/g cell h]. while the dissolved oxygen level of the fermented is steady, and when the air supply is suddenly turn off, the oxygen concentration will be decreased, see figure (1) with the following rate ……….. 2 …(2) since kla in (equation 1) is equal to zero. therefore, measuring the slope of the cl vs. t curve can estimate ro2 cx. and when turning on the airflow again, the dissolved oxygen concentration will be increased according to eq. (1) , which can be rearranged to result in a linear relationship as agitation and aeration.      −= xo l l ll cr dt dc ak cc 2 1* …(3) the plot of cl versus dcl/ dt + ro2 cx will result in a straight line which has the slope of 1/ (kla) and the y-intercept of cl*.. fig. 1. dynamic technique for the determination of kla , james m. lee . mathematically this means dco/dt= otr-our=kla (co*-co)-ro in this case ro is zero because of no microorganisms. the result of integrating is: ∫∫ − 1 * )1( o o o t l co c oo o dtak cc dc )( )( ( * * 0 * 0 ool o o o ttak tcc ccin −= − − )(** * )()( ol ttak oooo ccctc −−−−= 3. experimental work 3.1. list of instruments and substances in this work, 10l stirred bioreactor, which is connected electronically to a control board, was used. the bioreactor was supplied with dissolved oxygen meter probe, electro thermometer sensor and ph probe. air was provided by a compressor while nitrogen gas was obtained from storage cylinder connected to pressure gauge. the gas flow rate was regulated via rotmeters. deionized water and xanthan solution (1g/l) were used as media. two conditions were used: 1. constant air flow rate at16 l / min and variable rotation speed (250, 400, 550, and 700 rpm) 2. constant rotation speed at 325rpm and variable air flow rate (3, 7, 16 and 20 l/min) 3.2. procedure steps first the bioreactor vessel was filled with 6l deionized water. the temperature inside the bioreactor was held constant at 30°c. air flow rate and stirring speed were adjusted according to experiment set. then the oxygen electrode probe was calibrated with two points calibration i.e. zero and 100% saturation. then the air supply was turned off and nitrogen gas was provided until reaching the zero point. at this point, nitrogen gas was stopped. once the air was supplied again, the measurement was started by writing down the observed dissolved oxygen concentration in the xoll l crccdk dt dc 2 )( * −−= xo l cr dt dc 2 = zainab yaquob atiya al-khwarizmi engineering journal, vol. 8, no. 3, pp 7580 (2012) 78 medium each five seconds until reaching 100% of saturation. the same procedure was repeated for each experiment set and for the second medium, xanthan. the measurements were drawn between oxygen concentrations versus time. a regression was made to estimate the kla value for each experiment by using scientific graphing software program i.e. sigma plot. 4. results and discussion in figure 2, the results show that increasing air flow rate in deionized water medium from (3l/min) to (20l/min) caused an increase in the obtained kla from 0.011 to 0.022 1/sec respectively. the same behavior was obtained with xanthan medium as the kla values were increase from 0.005 to 0.012 1/sec, at the same range of air aeration. this behavior can be caused by the increased in the probability of oxygen bubbles hitting the oxygen probe on one hand. moreover, the ratio of air volume to liquid volume was increased on the other hand. however, this direct relation between kla and the air flow rate stopped at 16l air flow rate and started to decrease because the limitation of liquid capacity i.e. there is no space for more oxygen. 0 0.005 0.01 0.015 0.02 0.025 3 7 16 20 air flow rate [l/min] vo lu m et ric m as s tra ns fe r c oe ffi ci en t, kl a [1 / s ec ] xanthan water fig. 2. effect of increasing air flow rate on volumetric mass transfer coefficient kla at 325rpm constant stirring speed . also the results revealed a direct relation between kla and stirring speed. thus, the increase in kla values [0.015-0.04 1/sec] for water medium and [0.0060.026 1/sec] for xanthan medium were proportional to an increase in mixing speed [250-700rpm] respectively as shown in figure 3. the effect of stirring speed is by breaking down air bubbles and dispersion of air i.e. increasing the specific surface area. therefore, the mass transfer was improved. in addition, the film built on the oxygen probe by medium is highly affected by the stirring speed. therefore, the higher stirring speed is the thinner film. thus, the mass transfer will be better i.e. kla is bigger. furthermore, the obtained kla values in water were much greater than those observed in xanthan in both cases of varying aeration or mixing. since the xanthan is viscous compared to water, the capacity or space, for oxygen is less in its medium. moreover, the required energy to disperse air and mixing the xanthan is greater than water since the resistance is bigger because of the viscosity. thus the energy was dissipated. another effect is the film thickness on the oxygen probe. the film of xanthan is bigger than that of water; i.e. less mass transfer. 0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0 100 200 300 400 500 600 700 800 stirring speed [rpm] vo lu m at ric m as tr an sf er k oe ffi ci en t, kl a [1 /s ] 16 l/min air flow rate in water 16 l/min air flow rate in xanthan fig. 3. effect of increasing stirring speed on volumetric mass transfer coefficient kla at constant air flow rate 16l/min. 5. references [1] akita, k. and f. yoshida, .bubble size, interfacial area, and liquid-phase mass transfer coefficient in bubble columns,. i&ecproc. des. dev. 13 (1974):84.91. [2] biochemical engineering , james m. lee prentice-hall inc version 2.1, january 2002 [3] botton, r., d. cosserat, and j. c. charpentier, .operating zone and scale up of mechanically stirred gas-liquid xanthan water 16 l/min air flow rate in water 16 l/min air flow rate in xanthan zainab yaquob atiya al-khwarizmi engineering journal, vol. 8, no. 3, pp 7580 (2012) 79 reactors,. chem. eng. sci. 35 (198bowen, r. l., .unraveling the mysteries of shearsensitive mixing systems,. chem. eng. 9 (1986):55.63. [4] calderbank, p. h., .physical rate processes in industrial fermentation, part i: interfacial area in gas-liquid contacting with mechanical agitation,. trans. instn. chem. engrs. 36 (1958):443.459. [5] calderbank, p. h., .physical rate processes in industrial fermentation, part ii: mass transfer coefficients in gas-liquid contacting with and without mechanical agitation, trans. instn. chem. engrs. 37 (1959):173.185.0):82.89 [6] determination of volumetric mass transfer coeffeicient in a stirred , sparged bioreactor eric jackson http://prizedwriting.ucdavis.edu/past/199 7-1998/determination-of volumetric-masstransfer-coefficient-in-a-stirred-spargedbioreactor. [7] international critical tables.vol.3, new york, mcgraw-hill book co., 1928,p.271. [8] journal of environmental engineering and science july 1, 2008,http://www.highbeam.com/doc/1g1185430922.html [9] http://www.gatewaycoalition.org/ files/hidden/react/ch5/5_3f.htm [10] http://www.gatewaycoalition.org/ files/hidden/react/ch5/5_2f.htm http://prizedwriting.ucdavis.edu/past/199 http://www.highbeam.com/doc/1g1 http://www.gatewaycoalition.org/ http://www.gatewaycoalition.org/ )2012( 75 80 ، صفحة3، العدد 8 مجلة الخوارزمي الھندسیة المجلدزینب یعقوب عطیة 80 مفاعل البایولوجيكفاءة االنتقال للكتلة الحجمیة لل حساب زینب یعقوب عطیة جامعة بغداد/ الھندسة الخوارزمي كلیة / ة قسم الھندسة الكیمیائیة اإلحیائی zainaatia@yahoo.com :البرید االلكتروني الخالصة استخدمت التقنیة الحیویة في تقدیر قد و ,)كتلة الثابت انتقال ( ألحجميكتلة ألانتقال دراسة آثار التھویة وسرعة التحریك على معامل لقد ركز البحث على .من أجل تحقیق الھدف من ھذه الدراسة )الكتلة ثابت انتقال ( قیم -:ھماالحیوي مفاعل من محلولین في ال لتر ١٠ھذه الدراسة في ماستخدوقد .ماء خالي من االیونات. ١ )لتر/ غرام ١( xanthan محلول. ٢ .)كتلة الثابت انتقال ( المقارنة بین القیم التي تم الحصول علیھا من ذلك فان البحث قد شمل إلى إضافة للوسط الزراعي عندما تزرع الكائنات مماثال اسلوكحیث انھ یمتلك . الماءة التي یمتاز بھا مقارنة ببسبب اللزوجة العالی xanthanوقد استخدم محلول ،ةمما یؤثر على انتقال الكتل سطدي إلى تغییر في لزوجة الونمو الكائنات العضویة في المفاعل یؤ إن. في مفاعل حیوي العضویة كما .ألكتلةقیمة انتقال على ) rpm ٧٠٠ -٢٥٠(وتأثیر سرعة التحریك ) دقیقة \لتر ٣٠-٢٠(تأثیر معدل تدفق الھواء ھما أساسیینمتغیرین تمت دراسةقد و قیمة -مع زیادة في ثابت انتقال ألكتلة الجھاز،تحریك أداةل درجة الحرارة، وحجم السائل، وشكل وموقع خرى مثاألمتغیرات ثبات بقیة الأظھرت النتائج لذلك ، .للفقاعاتفقد تم الحصول على أفضل تشتت سرعة أعلى، وضع الجھاز على وعند وبموجب ھذا .الجھازتحریك أداةلكتلة مع زیادة سرعة انتقال او .قیمة ثابت انتقال ألكتلة أي أدى إلى زیادة مساحة نقل الكتلة الحجم مما /نسبة السطح فان ھذا سیزید من mailto:zainaatia@yahoo.com al-khwarizmi engineering!!! journal al-khwarizmi engineering journal, vol. 7, no. 2, pp 1 13 (2011) characterization of delamination effect on free vibration of composite laminates plate using high order shear deformation theory nabil hassan hadi * kayser aziz ameen ** department of mechanical engineering/ college of engineering/ university of baghdad * email: nabilhha@yahoo.com ** email: kayseraziz@yahoo.com (received 13 december 2010; accepted 24 may 2011) abstract a dynamic analysis method has been developed to investigate and characterize embedded delamination on the dynamic response of composite laminated structures. a nonlinear finite element model for geometrically large amplitude free vibration intact plate and delamination plate analysis is presented using higher order shear deformation theory where the nonlinearity was introduced in the green-lagrange sense. the governing equation of the vibrated plate were derived using the variational approach. the effect of different orthotropicity ratio, boundary condition and delamination size on the non-dimenational fundamental frequency and frequency ratios of plate for different stacking sequences are studied. finally the discrepancy of the results was 17.4906% when the severe nonlinearity is considered. keywords: delamination, high order shear deformation, plate, free vibration, nonlinear finite element method. 1. introduction interlayer debonding or delamination is a prevalent form of damage phenomenon in laminated composites. delamination can be often pre-existing or generated during service life. for example, delamination often occur at stress free edges due to the mismatch of properties at ply interfaces and it can also be generated inside the plate by external forces such as out of plane loading or impact during the service life. the existence of delamination not only alters the load carrying capacity of the structure, it can also affect its dynamic response. thus the investigation of delamination is an important technology that must be addressed for the successful implementation and improved reliability of such structures. all type of damages in composite structure result in change in stiffness, strength and fatigue properties. measurement of strength or fatigue properties during damage development is not feasible because destructive testing is required. however, stiffness reduction due to damage can be measured since damage directly affects structural response, which provides a promising method for identifying the occurrence, location and extent of the damage from measured structural dynamics characteristics. existence of delaminations causes reduction in natural frequencies and increase in vibratory damping. several authors studied the linear and an nonlinear free vibration and used different shear theory. malekzadeh 2007 studyied the effect of different parameters on the convergence and accuracy of natural vibration of the method a differential quadrature for large amplitude free vibration analysis of laminated composite skew plates, the governing equations are based on the thin plate theory (classical linear theory) and geometrical nonlinearity is modeled using green’s strain in conjunction with von karman assumption. on the other hand the ganapathi, etal. 2009 investigation of the free vibration characteristics of simply supported anisotropic composite laminates using analytical approach the this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ nabil hassan hadi al-khwarizmi engineering journal, vol. 7, no. 2, pp 1 13 (2011) 2 formulation is based on the first order shear deformation theory, the governing equation are obtained using energy method. liangjin and zhengneng 2000 presented a three dimensional ,model for the analysis of local buckling of stitched composite laminates with an embedded elliptical delamination near the surface, they investigated the effects of stitching, delamination size, delamination orientation and stacking sequence on buckling strains by using the rayleigh ritz energy method. heung etal 2003 investigated and characterized the effect due to the presence of discrete single and multiple embedded delaminations on the dynamic response of composite laminated structures with balanced/unbalanced and arbitrary stacking sequences in terms of number placement, mode shapes and natural frequencies. a new generalized layerwise finite element model is developed by dongwei and christian 2004 an analytical solution to the free vibration of composite beams with two non overlapping delaminations is presented, the euler bernoulli beams using the delaminations as their boundaries, the continuity and the equilibrium conditions are satisfied between adjoining beams. alberto and etal 2005 developed the analytical delamination of the strain energy release rates in a delaminated laminate by means of a model of plates which provides no singular stresses and they predicted the delamination criteria. wang and dong 2005 used the energy method to study hygrothermal effects on local buckling for different delaminated shapes near the surface of cylindrical laminated shells, the effect of non-linear obtained by considering transverse displacements of sub laminate shells and the young’s modulus, thermal and humidity expansion coefficients of material are treaded as functions of temperature. yang and fu 2006 discussed the effects of delamination sizes, depths, boundary conditions, the material properties and the laminate stacking sequences on delamination growth, based on the variational principle of moving boundary and used classical theory for cylindrical shells. christian and dongwei 2007 studied the analytical models and numerical analysis for free vibration of delaminated composites, and they discussed the influence of delamination on the natural frequencies and the mode shapes of composite laminates in addition other factors affecting the vibration of the delaminated composites are discussed. yang etal. 2007 discussed the effects of delamination sizes, depths, boundary conditions, the material properties and the laminate stacking sequences on delamination growth, based on the variational principle of moving boundary and considering the contact effect between delamination regions, the first order theory and nonlinear governing equations for the cylindrical shells are derived. sang and dae 2007 studied buckling behaviors of laminated composite structures with a delamination using the enhanced assumed strain (eas), the eas three dimensional finite element formulation described and focused on the significant effects of the local buckling for various parameters, such as size of delamination, aspect ratio, width to thickness ratio, stacking sequences and location delamination and multiple delaminations. züleyha and mustafa 2008 studied the effect of the size of beneath delaminations has no significant on the critical buckling load and compressive failure load of e-glass/epoxy composite laminates with multiple large delaminations, a numerical and experimental study is carried out to determine the buckling load of rectangular composite plates, for the experiments (0º/90º/0º/90º)s oriented cross-ply laminated plates with multiple large delaminations and without delamination are produced by using hand lay up technique and the results are compare with results obtained by ansys 11.0 software and good agreement obtained. alnefaie 2009 developed a three dimensional finite element model of delaminated fiber reinforced composite plates, a classical plate theory is studied during the analyzing their dynamics natural frequencies and modal displacements calculated for various case studies with different dimensions and delamination characteristics. this work is investigated theoretically by using finite element method the effect of delamination on the natural frequency of the composite material with considering the severe nonlinearity, which is studied the modal analysis of intact and delamination plate. 2. mathematical model 2.1. displacement field a plate of length a, width b and thickness h is composed of n number of orthotropic layers of uniform thickness. the (α, β, ) was rectangular coordinate. the following displacement field for the laminated plate based on the high shear deformation theory (hsdt) is considered to derive the mathematical model. the displacement along the (α, β, ) coordinates is : this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ nabil hassan hadi al-khwarizmi engineering journal, vol. 7, no. 2, pp 1 13 (2011) 3   1 3 1 2 1,,,   utu   2 3 2 2 2,,,   vtv   wtw ,, …(1) where t is the time, (u,v,w) are the displacements of a point on the mid-plane and 1 and 2 are the rotations at ( 0 ) of normal to the mid-plane respect to the α and β-axes, respectively, 2121 ,,,  are high order terms of toyler series expansion defined at the mid-plane (panda and singh, 2009). 2.2. strain –displacement relation the nonlinear green lagrange strain displacement relation for the laminated plate can be expressed as follows (panda and singh, 2009).                                                                                                                                                                                                                                                                                                                                                                                                                                                                      wwuuvv wwvvuu wwvvuu wuv wvu wv wu vu v u 2 2 22 1 222 222 , , , , , or ,      nll   …(2) where  l and  nl are the linear and nonlinear strain vectors respectively these terms can be considered when the thickness is increased or is equal to (a/10). substituting equation (1) b equation (2), the strain – displacement relation of the laminated plate is further expressed as:                                                                                                                                           6 4 6 5 6 6 6 2 6 1 2 4 2 5 2 6 2 2 2 1 2 5 4 5 5 5 6 5 2 5 1 1 4 1 5 1 6 1 2 1 1 4 4 4 5 4 6 4 2 4 1 0 4 0 5 0 6 0 2 0 1 2 2 2 2 1 2 2 2 2 1 2 2 2 2 1                                  nll                                                                                                                                                      0 0 2 2 1 2 2 2 2 1 2 2 2 2 1 2 2 2 2 1 10 6 10 2 10 1 6 9 4 9 5 9 6 9 2 9 1 5 8 4 8 5 8 6 8 2 8 1 4 7 4 7 5 7 6 7 2 7 1 3 4 3 5 3 6 3 2 3 1 3                            …(3) hence the above equation can be rearranged as:              nlnlllnll   2 1 …(4) where   } { 3 4 3 5 3 6 3 2 3 1 2 4 2 5 2 6 2 2 2 1 1 4 1 5 1 6 1 2 1 1 0 4 0 5 0 6 0 2 0 1    l   } { 10 6 10 2 10 1 9 4 9 5 9 6 9 2 9 1 8 4 8 5 8 6 8 2 8 1 7 4 7 5 7 6 7 2 7 1 6 4 6 5 6 6 6 2 6 1 5 4 5 5 5 6 5 2 5 1 4 4 4 5 4 6 4 2 4 1        nl 2.3. stress strain relations in the analysis of composite laminated materials, the assumption of plane stress is usually this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ nabil hassan hadi al-khwarizmi engineering journal, vol. 7, no. 2, pp 1 13 (2011) 4 used for each layer because fiber reinforced material is utilized in beam, plate, cylinders, spherical and other structural shapes which have at least one characteristic geometric dimension in an order of magnitude less than the other two dimensions. in this case the stress components ( 13233 ,,  ) are set to zero. then the strain displacement relations, for any general kth orthotropic composite lamina with an arbitrary fiber orientation angle with reference to the coordinate axes (α, β, ) is written as (panda and singh, 2009):                                                                    kkk qq qq qqq qqq qqq 4 5 6 2 1 4445 4555 662616 262212 161211 000 000 00 00 00                …(5) where :   4 22 22 6612 4 1111 sin cossin)2(2cos   q qqqq )sin(cos cossin)4( 44 11 22 66221112     qqqqq   4 22 22 6612 4 1122 cos cossin)2(2sin q qqqq     cossin)2 (cossin)2( 3 66 2212 3 66121116   q qqqqqq   3 66 2212 3 66121126 cossin)2 (cossin)2(   q qqqqqq )cos(sincossin )22( 44 66 22 6612221166    q qqqqq  2 55 2 4444 sincos qqq   sincos)( 445545  qqq  24425555 sincos qqq  2.4. strain energy of the laminate energy and variational principle offered great simplification to many derivations of fundamental equations in elasticity. also have been used to introduce and implement approximation techniques for structural systems. strain energy is defined as the work done by the internal stresses which caused elongation or shear strains. the strain energy of the plate can be expressed as:      v i t i dvu  2 1 …(6) by substituting the strains from equation (2) and stresses from equation (5) into equation (6) the strain energy can be expressed as :       v inll t inll dvqu  2 1                     da d d d d inl t inl il t inl inl t il il t il                                 4 3 2 1 4 1 2 1 2 1 2 1 …(7) where :            n k l t l k k dqd 1 1 1               n k nl t l k k dqd 1 2 1               n k l t nl k k dqd 1 3 1               n k nl t nl k k dqd 1 4 1    where : n is the numbers of layers. 2.5. kinetic energy of the vibrating plate the kinetic energy expression of a vibrated plate can be expressed as     v t dvt 2 1   …(8) where,  and  are the density, displacement vector which is first derivative with respect to time, respectively. the nodal velocity vector can be expressed as: this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ nabil hassan hadi al-khwarizmi engineering journal, vol. 7, no. 2, pp 1 13 (2011) 5                             f w v u w v u i                                                2 1 2 1 2 1 000000100 30200010 03020001 …(9) where, [f] is the function of the thickness coordinate. then the kinetic energy for ‘n’ number of orthotropic layered composite plate obtained by substituting equation (9) into equation (8) gives:                  a n k kttk k fft dad 2 1 1 1          a da 2 1   mt t …(10) where,          n k kt ffm 1 k 1-k d    is the inertia matrix. 3. solution technique the displacement vector can be conceded to the form by employing the fem     iin   …(11) where :    tiiii wvu 212121   the equations of strain for linear and nonlinear of large deflections, are studied in equation (4) and nonlinear displacement is shadied in equation (1), when they are substituted into equation (7), the strain energy can be written as:                                                                a t inl t i t inl iil t i t inl iinl t i t il iil t i t il da bdb bdb bdb bdb u     4 3 2 1 4 1 2 1 2 1 2 1 …(12) where      iiinl gab  , [a]33×27 is function to the displacements and [g]27×9 is the product form of differential operator and shape function in the nonlinear strain terms. [bl]20×9 is the product form of the differential operator and nodal interpolation function in the linear terms. the final form of governing equation for the nonlinear free vibration laminated plate panel is obtained by using hamilton’s principle. it can be viewed and axiom, from which other axioms like newton’s second law, let the potential energy be defined as ( )wu  , where u is the strain energy and w is the work done and the lagrangian as the function l where ( l = (t – u+w)). hamilton’s principle states that the actual displacement that the body actually goes through from instant (t1) to instant (t2) out of many possible paths, is that which achieves an extremum of the line integral of the lagrangian function. this is achieved if the variation of the time integral of the lagrangian is set to zero:   2 1 0 t t dtl …(13) hamilton’s principle can be used to find the compatible set of equations of motion and boundary conditions for given stresses and strains. this is done by substituting the equations for strain energy equation (12) and kinetic energy equation (10) into the equation (13), performing the integration by parts, and setting the coefficients of the displacement variations (also called virtual displacement) to zero. the lagrangian becomes (marco, 2008).          0  nll kkm  …(14) where   is the displacement vector, [m], [kl] and [knl] are the global mass matrix and global linear stiffness matrix and nonlinear stiffness matrix depend on the displacement vector respectively. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ nabil hassan hadi al-khwarizmi engineering journal, vol. 7, no. 2, pp 1 13 (2011) 6 4. damage modeling defect and damages cause the laminates to lose their strength and rigidity and also the safe working life is reduced. defects and damages can propagate in at any time like manufacturing, in service or in design due to discontinuities such as cut out and play drops. the investigation of defects and damages are presented. by using the following expansion of the displacements through the thickness of the plate:      nd uzh utu 1 1 3 1 2 1 ),()( ,,,        nd vzh vtv 1 2 3 2 2 2 ),()( ,,,   (15)     nd wzhwtw 1 ),()(,,  where the step functions h  are computed in terms of heaviside functions h  as : 1)()(  jzzhzh for jzz  0)()(  jzzhzh for jzz  …(16) and the nd is the number of delaminations. the jumps in the displacements at the jth delaminated interface are given by vu , and w  . using the step functions )(zh  , can model any number of delaminations through thickness; the number of additional variable is equal to the number of delaminations considered(barbero and reddy, 1991). then substituting equation (16) into the nonlinear green lagrange strain displacement relation for the laminated shell, equation (2) will be:                                                                         4 4 4 5 4 6 4 2 4 1 4 4 4 5 4 6 4 2 4 1 0 4 0 5 0 6 0 2 0 1 0 4 0 5 0 6 0 2 0 1 2 2 2 2 1 2 2 2 2 1 d d d d d d d d d d nll                                                                                                                                                                                                                                                                                                                                  0 0 2 2 1 2 2 2 2 1 2 2 2 2 1 0 0 2 2 1 2 2 2 2 1 2 2 2 2 1 2 2 2 2 1 2 2 2 2 1 2 2 2 2 1 10 6 10 2 10 1 6 9 4 9 5 9 6 9 2 9 1 5 8 4 8 5 8 6 8 2 8 1 4 7 6 7 2 7 1 7 4 7 5 7 6 7 2 7 1 3 4 3 5 3 6 3 2 3 1 3 6 4 6 5 6 6 6 2 6 1 6 4 6 5 6 6 6 2 6 1 2 4 2 5 2 6 2 2 2 1 2 5 4 5 5 5 6 5 2 5 1 5 4 5 5 5 6 5 2 5 1 1 4 1 5 1 6 1 2 1 1                                                               d d d d d d d d d d d d d …(17) the generalized displacements (dof) in this case are:  wvuwvu  ,,,,,,,,,,, 212121  . the effect of delamination on the stiffness is much higher compared to the mass, hence it can be considered the same mass matrix in equation (10). 5. numerical results and discussion a nonlinear finite element code using the present displacement field plate model in greenlagrange sense in the framework of the hsdt is presented. the validation and accuracy of the present algorithm are examined by comparing the results with those available in the literature. the effect of different combinations of the thickness ratio (a/h), amplitude ratio (wmax/h), where wmax is the maximum deflection of plate and h is the thickness, and various boundary conditions on the composite plate response are also examined. the following sets of boundary conditions are used for the present analysis; a) simply support boundary conditions (s): this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ nabil hassan hadi al-khwarizmi engineering journal, vol. 7, no. 2, pp 1 13 (2011) 7 0222  wv at x=0,a 0111  wu at y=0,b b) clamped boundary conditions (c): 0212121  wvu at x= 0,a 0212121  wvu at y= 0,b fig.1. convergence study of non-dimensional frequency for square plate having ssss boundary condition with different stacking sequences. fig.2. convergence study for frequency ratio of square laminated plate with ssss boundary condition with different stacking sequences. a convergence of the mathematical model developed for laminated plate is presented in figures (1) and (2) which shown the nondimensional fundamental frequency (     2 2 eh a ln   ), and frequency ratio   l nl   against mesh division respectively for simply support boundary condition and for different stacking sequences, the results are plotted using the material properties (e1=181 gpa, e2=7.17gpa, g23=6.71gpa, υ12=0.28, and the geometry parameters are a/b=1, a/h=10). figures show that the convergence is a (5x5) mesh, and that it is used to compute the results throughout the study. a comparison of the linear free vibration with out defect results with classical plate theory (cpt) and the layerwise plate theory (lwst) and the generalized lamination plate theory (glpt) is also included. (glpt, though identical in formulation with the layerwise plate theory (lwst), does not consider the variation of the transverse displacement, w, through the thickness) (samuel ,1992); and the results were obtained from a 3-d orthotropic elasticity theory (noor,1975). the material properties and the geometries details of this comparison are: psiee 6 32 100.1  ,  2 1 e e 3, 10, 20, 30, psigg 6 1312 106.0  , psig 6 23 105.0  , 25.01312  , 24.023  , 20a inch, 20b inch, 10 h a . the results are summarized in table (1). the differences are more pronounced between the present results and the results existing in (samuel, 1992 and noor, 1975), because the present work used the framework of the high order shear theory and the other results used the framework of the first order theory and classical theory. when the plate containing some defect such as delamination, this causes decreasing in natural frequency with diverge in some results because the present work used in the framework of the high order shear theory and geometrical nonlinearity modeled using green’s strain. the results are shown in table (2). the linear fundamental frequency is increasing with the increase in modular ratio. the frequency ratio is decreasing with the increase in modular ratio. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ nabil hassan hadi al-khwarizmi engineering journal, vol. 7, no. 2, pp 1 13 (2011) 8 table 1, nondimensional fundamental frequency of (0/90/0) and (0/90/0/90/0) cross-ply simply support plates. no. of layers method 22 11 e e 3 10 20 30 3 lwst 0.2671 0.338 0.3897 0.4197 glpt 0.2645 0.3368 0.3897 0.4205 3-d elasticity 0.2647 0.3284 0.3824 0.4109 cpt 0.2919 0.4126 0.5404 0.6433 present work 0.25699 0.343019 0.395955 0.4245764 5 lwst 0.2671 0.3429 0.4012 0.4354 glpt 0.2645 0.3415 0.4012 0.4367 3-d elasticity 0.2659 0.3409 0.3997 0.4314 cpt 0.2919 0.4126 0.5404 0.6433 present work 0.332695 0.44010713 0.506355 0.5417735 table 2, effect of material orthotropy on nonlinear free vibration ratio   l nl   of delamination laminated plate. h wmax 2 1 e e 3 5 10 15 dnl dl dnl   dnl dl dnl   dnl dl dnl   dnl dl dnl   [0 /9 0/ 0/ 90 ]s 0.5 0.271253341 1.439972862 0.496753765 1.005498833 0.463875194 1.074907011 0.479950624 1.114002269 1 0.377780936 1.22934653 0.567228255 0.854560912 0.67313799 0.689274524 0.635394303 0.812535895 1.5 0.518695812 1.010721 0.648812609 0.701566829 0.662164365 0.735156446 0.53275242 1.031948538 2 0.512059386 1.008796066 0.649101227 0.700989768 0.540102051 1.00545388 dl 56.05608734 80.72544339 52.7409818 56.3617073 dl 0.231787883 0.031989607 0.379276273 0.336781921 [4 5/ -4 5/ 45 /45 ]s 0.5 0.524938484 1.008676236 0.346213883 1.488284445 0.302825431 1.568922348 0.288723595 1.591158038 1 0.52655556 1.005162538 0.535180065 1.122745485 0.612533832 0.984962028 0.585499164 1.008888609 1.5 0.547574918 1.000895833 0.670324913 0.823119111 0.569620939 1.094049155 0.600627397 1.00808513 2 0.549970942 0.995595058 0.597129584 1.005869819 0.583307751 1.093122543 0.618881411 1.007317623 dl 56.04256347 56.17882202 51.77412417 56.20827023 dl 0.169927471 0.175307231 0.248169694 0.188396351 [0 /4 5/ -4 5/ 90 ]s 0.5 0.770996366 1.439424677 0.31815017 1.44382817 0.341425355 1.320595998 0.457053434 1.09130257 1 0.321721145 1.38750057 0.427610259 1.231845439 0.449647998 1.084938451 0.516577858 1.006602312 1.5 0.530488979 1.009934922 0.546070899 1.008082255 0.546266667 0.985149923 0.537217179 1.013647779 2 0.529218539 1.008795481 1.007125703 0.669394579 0.705624484 0.898161014 dl 56.05506261 56.1860639 52.25566967 56.36350015 dl 0.203232959 this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ nabil hassan hadi al-khwarizmi engineering journal, vol. 7, no. 2, pp 1 13 (2011) 9 the variation of the frequency ratio for different support conditions and the amplitude ratios are analyzed for anti-symmetric and symmetric lamination schemes. the results are figured in table (3) . the effects of three different support conditions are examined for the frequency ratio such as all sides simple support (ssss), all sides clamped (cccc), and two sides simply support and two sides clamped (scsc). the material properties and other parameters are ( 15 2 1 e e , ,5.0 2 12 e g ,2.0 2 23 e g 25.0 , ,1b a ,10h a and. it is found that the fundamental frequency increasing with increase the amplitude ratio in all typs of boundary condition. table 3, effect of variable boundary condition with delamination defect on the frequency ratio. h wmax boundary condition ssss scsc cccc dnl dl dnl   dnl dl dnl   dnl dl dnl   [0 /9 0/ 0/ 90 ]s 0.5 0.491758607 1.088579493 0.538991224 0.987414065 0.062150024 2.104234903 1 0.643715012 0.793992918 0.220360475 1.73745255 0.158652081 1.8765753 1.5 0.543415532 1.008398321 0.102742944 1.981654155 0.050560733 2.100182456 2 0.550597436 0.9825083 0.393293891 1.326413856 0.074813047 2.027026282 dl 56.3617073 57.49825598 57.67798328 dl 0.336781921 0.323434162 0.321415743 [4 5/ -4 5/ 45 /45 ]s 0.5 0.133385624 1.591158038 0.879263163 0.952480486 0.023840315 2.190273943 1 0.494974975 1.008888609 0.393103954 1.353254954 0.000917226 2.23183492 1.5 0.513407113 1.00808513 0.210310709 1.745408323 0.419374326 1.283481406 2 0.535647682 1.007317623 0.00169324 2.184253397 0.553357876 0.977484197 dl 56.20827023 56.4956763 57.02122715 dl 0.333873817 0.335140781 0.329024622 [0 /4 5/ -4 5/ 90 ]s 0.5 0.457053433 1.09130257 0.055274753 2.119779963 0.018531167 2.202208867 1 0.516577858 1.006602312 8986.481765 2.004210859 0.171728119 1.847245944 1.5 0.537217179 1.013647779 0.365342642 1.403137192 0.213629079 1.739024909 2 0.58431569 0.898161014 0.432516003 1.242230958 0.245671236 1.651955386 dl 56.36350015 56.98452359 57.32010532 dl 0.336764848 0.329470127 0.325554679 the effect of delamination on the natural frequency, decreasing the natural frequency with increases the size of defect, because of the increase in the delamination size this leads to an increase in the reduction in stiffness matrix the results are shown in table (4). the mode shape of the intact plate and delamination plate show in figures (3) and (4) the decreasing in the mode shape when the plate containing the delamination. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ nabil hassan hadi al-khwarizmi engineering journal, vol. 7, no. 2, pp 1 13 (2011) 10 table 4, effect of delamination size on the frequency ratio. h wmax delamination size b(8x8)cm a(6.6x6.6)cm c(4x4)cm dnl dl dnl   dnl dl dnl   dnl dl dnl   [0 /9 0/ 0/ 90 ]s 0.5 0.479950624 1.114002269 0.193951872 2.55757464 0.378470183 2.95283291 1 0.635394303 0.812535895 0.223217546 2.72598089 0.299101517 2.895090839 1.5 0.53275242 1.031948538 0.201466386 2.653521464 0.313329257 2.900578336 2 0.540102051 1.00545388 0.036672763 2.266430313 0.281039999 2.800679241 dl 56.3617073 57.51626797 57.8864755 dl 0.336781921 0.323196004 0.318839707 [4 5/ -4 5/ 45 /45 ]s 0.5 0.133385625 1.591158038 0.144176768 2.100779902 0.24478903 2.28551029 1 0.494974977 1.008888609 0.093482347 2.184449945 0.386776317 2.770363377 1.5 0.513407114 1.00808513 0.096838416 2.272344147 0.48287703 3.072108791 2 0.535647682 1.007317623 0.011386133 2.144596099 0.387957769 3.010891227 dl 56.20827023 56.31581296 56.68828199 dl 0.333873817 0.332599325 0.328185181 [0 /4 5/ -4 5/ 90 ]s 0.5 0.457053434 1.09130257 0.302822548 1.401300962 0.345981887 2.705373944 1 0.516577858 1.006602312 0.066301456 2.220298611 0.316935026 2.742178577 1.5 0.537217179 1.013647779 0.171090219 1.815587184 0.238173784 2.712011012 2 0.58431569 0.898161014 0.174845634 1.782895011 0.229407794 2.656357541 dl 56.36350015 56.91225624 57.28434623 dl 0.336764848 0.330307578 0.325929157 figure.3. the mode shape of plate of the intact and delamination plate [0/90/0/90]s. -1.5 -1 -0.5 0 0.5 1 1.5 0 0.1 0.2 0.3 0.4 mode 1 mode 1 del mode 2 mode 2 del mode 3 mode 3 del this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ nabil hassan hadi al-khwarizmi engineering journal, vol. 7, no. 2, pp 1 13 (2011) 11 figure.4. the contour and surface mode shape of plate of the intact and delamination plate [0/90/0/90]s. 6. conclusion the geometrically nonlinear free vibration analysis of composite plate with and without containing the delamination is investigated using nonlinear finite element method in the framework of a higher order shear deformation theory in green-lagrange sense. the governing equation of the vibrated plate is derived using the variational approach. the frequency amplitude relations for the nonlinear free vibrated plate are computed using eigenvalue formulation and are solved employing a direct iterative procedure. based on the numerical results the following conclusions are drawn.  the validation shows the necessities of taking into account full nonlinearity.  the two dimensional finite element model proposed can predict accurately the dynamic behaviors of a laminated composite plate with internal delamination at arbitrary location.  the discrepancy of the results when considered the nonlinear green lagrange strain displacement was (17.4906% when the severe nonlinearity is considered).  local internal delamination has slight effect on the natural frequencies of the laminated composite plate although the extent of the natural frequency variation increase with both the delamination dimension and the order of the natural frequency. notations  ,, rectangular coordinate axes wvu ,, displacement along the  ,, coordinate    nll  , linear and nonlinear strain vectors  q transferred reduced elastic constant e young’s modulus (gn/m2) g shear modulus (gn/m2) υ poisson’s ratio ρ density t kinetic energy wmax/h amplitude ratio ωnl/ωl frequency ratio κdl, κdnl damage ratio for linear and nonlinear respectively actondelamenatiact intint /)(   ) delamination plate mode (1) mode (2) mode (3) intact plate mode (1) mode (2) mode (3) this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ nabil hassan hadi al-khwarizmi engineering journal, vol. 7, no. 2, pp 1 13 (2011) 12 7. reference [1] panda s. k., singh b. n., “non-linear free vibration of spherical shell panel using high order shear deformation theorya finite element approach”, journal of pressure vessels and piping, vol.(86), pp. 373-383, november 2009. [2] malekzadeh p., “a differential quadrature nonlinear free vibration analysis of laminated composite skew thin plates”, journal of thin wall structures, vol. (45), pp. 237-250, january 2007. [3] ganapathi m., amit kalyani, bhaskar mondal, prakash t., “free vibration analysis of simply supported composite laminated panels”, journal of composite structures, vol. (90), pp. 100-103, february 2009. [4] liangjin gui and zhengneng li, “delamination buckling of stitched laminates”, journal of composites science and technology, vol. (61),pp. 629-636, june 2000. [5] heung soo kim, aditi chattopadhyay and anindya ghoshal, “characterization of delamination effect on composite laminates using a new generalized layerwise approach”, journal of computers & structures, vol. (81), pp. 1555-1566, february 2003. [6] dongwei shu and christian n. della, “free vibration analysis of composite beams with two nonoverlapping delaminations”, journal of international mechanical sciences, vol. (46), pp. 509-526, may 2004. [7] alberto diaz diaz, jean françois caron and alain ehelacher, “analytical determination of the mode i, ii, and iii energy release rates in a delaminated laminate and validation of a delamination criterion”, journal of composite structures, vol. (78), pp. 424-432, december 2005. [8] wang x. and dong k., “local buckling for triangular and lemniscate delaminations near the surface of laminated cylindrical shells under hygrothermal effects”, journal of composite structures, vol. (79), pp. 6775, december 2005. [9] yang j. h. and fu y. m., “delamination growth of laminated composite cylindrical shells”, journal of theoretical and applied fracture mechanics, vol. (45), 2006. [10] christian n. della and dongwei shu, “vibration of delaminated composite laminates”, journal of applied mechanics, vol. (60), pp. 1-20, january 2007. [11] yang jinhua, fu yiming and wang xianqiao, “variational analysis of delamination growth for composite laminated cylindrical shells under circumferential concentrated load”, journal of composites science and technology, vol. (67), pp. 541-550, 2007. [12] sang youl lee and dae yong park, “buckling analysis of laminated composite plates containing delaminations using the enhanced assumed strain solid element”, journal of solids and structures, vol. (44), pp. 80068027, may 2007. [13] züleyha aslan and mustafa şahin, “buckling behavior and compressive failure of composite laminates containing multiple large delaminations”, journal of composite structures, vol. (89), pp. 382390, september 2008. [14] alnefaie k., “finite element modeling composite plates with internal delamination”, journal of composite structures, vol. (90), pp. 21-27, january 2009. [15] marco amabili, “nonlinear vibrations and stability of shells and plates”, cambridge university press, 2008. [16] samuel kinde kassegne, “layerwise theory for discretely stiffened laminated cylindrical shell”, virginia polytechnic institute and state university, ph. d. , thesis, december 1992. [17] noor, a.k., “force vibration of multilayer composite plates”, vol. (11), pp. 1038-1051, 1975. [18] r. akkerman., “laminate mechanics for balance woven fabrics”, journal of composite, vol. 37, pp.(108-116),2006. [19] d. gay, s. v. hoa, s. w. tasi, “composite materials design and application”, boca raton, london, new york, washington, 2003. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ 13 ، صفحة2، العدد 7مجلة الخوارزمي الھندسیة المجلد نبیل حسن ھادي 1 )2011( 13 الحرة للصفائح المركبة المتعددة باستعمال نظریة تاثیر االنخالعات على االھتزازات القص ذات الرتب العالیة ** قیصر عزیز امین * نبیل حسن ھادي جامعة بغداد/ كلیة الھندسة /قسم الھندسة المیكانیكیة nabilhha@yahoo.com : االلكتروني البرید* kayseraziz@yahoo.com :االلكتروني البرید** الخالصة في ھذا البحث تم . ان البحث واسع في الطرق التحلیل الدینمیكي الیجاد الخواص الدینماكیة للمواد المركبة المتعددة الطبقات والحاویة على االنخالعات وللصفائح الحاویة على ئح بواسطة طریقة العناصر المجددة الالخطیة بالنسبة لالشكال الھندسیة وللسعات االھتزازیة العالیة للصفائح السلیمة تحلیل الصفا تم البحث . لتقریبیةاالنخالعات وباستعمال نظریات القص ذات المرتبات العالیة وتم اشتقاق المعادالت الجامعة للصفائح المھتزة باستعمال طریقة المتغیرات ا خالعات الموجودة في الصفائح وتاثیرھم على التردادت في ھذا العمل دراسة تاثیر تغیر نسبة الخواص التعامدیة للمواد المركبة، الشروط الحدیة وحجم االن .عند االخذ بنظر االعتبار العوامل الالخطیة %) ١٧,٤٩(ولقد تم الحصول على تناقض في النتائج بمقدار . الطبیعیھ للصفائح المركبة this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ جاسم وعلي وثامر al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 6282 (2013) numerical analysis of double diffusive laminar natural convection in a right angle triangular solar collector jasim m. mahdi* ali m. rasham** thamir h. ali*** *,**department of energy engineering / college of engineering / university of baghdad *** department of manufacturing engineering / al-khwarizmi college of engineering / university of baghdad *e-mail: jasim_ned@yahoo.com **e-mail: ali_mohsen7788@yahoo.com ***e-mail: thamir.2008@yahoo.com (received 6 december 2012; accepted 12 january 2014) abstract a numerical study of the double-diffusive laminar natural convection in a right triangular solar collector has been investigated in present work. the base (absorber) and glass cover of the collector are isothermal and isoconcentration surfaces, while the vertical wall is considered adiabatic and impermeable. both aiding and opposing buoyancy forces have been studied. governing equations in vorticity-stream function form are discretized via finite-difference method and are solved numerically by iterative successive under relaxation (sur) technique. computer code for matlab software has been developed and written to solve mathematical model. results in the form of streamlines, isotherms, isoconcentration, average nusselt, and average sherwood number, are presented for wide range of the buoyancy ratio , angle of inclined glass cover with horizontal coordinate , lewis number , thermal rayleigh number , and prandtl number . the results show that above parameters have strong influences on the patterns of streamline, isotherms, isoconcentration, average nusselt number and average sherwood number. results show that a decrease in the angle of inclined glass cover with horizontal coordinate ( leads to increase average nusselt number and average sherwood number. for (n > 0), both average nusselt number and average sherwood number increase with increasing of buoyancy ratio and rayleigh number. by contrast for ( these values decreases. also, increasing of the buoyancy ratio for positive (n > 0), at the same rayleigh number enhance the heat and mass transfer rate. a comparison is made with the previous numerical results and it found to be reveal a good agreement. keywords: double diffusion, heat and mass transfer, laminar natural convection, solar collector. 1. introduction a double diffusive natural convection in solar collector of various forms occupies a large portion of heat transfer literature. a few numbers of studies have considered the triangular geometry, which is encountered in several practical engineering applications, such as water desalination plants. hitesh n panchal, etc., [1] studied effect of varying glass cover thickness on performance of solar still: in a winter climate conditions. six-month-study showed that, lower glass cover thickness increases the distillate water output, water temperature, evaporative heat transfer coefficient, convective heat transfer coefficient as well as efficiency of solar still. hiroshi tanaka, [2] investigated a theoretical analysis of basin type solar still with flat plate external reflector. narjes setoodeh, etc., [3] reviewed the modeling and determination of heat transfer coefficient in a basin solar still using cfd. the simulation results were compared with the available experimental data of basin solar still. m.m. rahman, etc. [4] presented a double diffusive natural convection in triangular solar collector. the study deals with natural convection jasim m. mahdi al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 6582 (2013) 66 flow resulting from the combined buoyancy effects of thermal and mass diffusion inside a triangular shaped solar collector. mohamed a. teamah, [5] researched numerically a doublediffusive convective flow in a rectangular enclosure with the upper and lower surfaces being insulated and impermeable. constant temperatures and concentration are imposed along the left and right walls of the enclosure. in addition, a uniform magnetic field is applied in a horizontal direction. laminar regime is considered under steady state condition. ching-yang cheng, [6] employed the double diffusive natural convection near an inclined wavy surface in a fluid saturated porous medium with constant wall temperature and concentration. effects of angle of inclination, lewis number, buoyancy ratio, and wavy geometry on the heat and mass transfer characteristics are studied. the same author [7] analyzed the coupled heat and mass transfer by natural convection near a vertical wavy surface in a non-newtonian fluid saturated porous medium with thermal and mass stratification. the surface of the vertical wavy plate is kept at constant wall temperature and concentration. the total heat transfer rate and the total mass transfer rate of vertical wavy surfaces are higher than those of the corresponding smooth surfaces. yasin varol, etc., [8] performed that steady-state free convection heat transfer in a right-angle triangular enclosure, whose vertical wall insulated and inclined and bottom walls are differentially heated. the governing equations are obtained using darcy model. the governing equations were solved by finite difference method and solution of algebraic equations was made via successive under relaxation method. ali j. chamkha, etc., [9] scrutinized hydromagnetic double diffusive convection in a rectangular enclosure with opposing temperature and concentration gradients. constant temperatures and concentrations are imposed along the left and right walls of the enclosure and a uniform magnetic field is applied in the x-direction. the thermal and compositional buoyancy forces are assumed to be opposite. e. fuad kent, etc., [10] examined numerically natural convection in nonrectangular enclosures. streamlines and isotherms are presented for different triangular enclosures with different boundary conditions and rayleigh numbers. mean nusselt numbers on hot walls are also calculated in order to make comparisons between different cases. e. f. kent, [11] explored the numerical analysis of laminar natural convection in isosceles triangular enclosures for two different thermal boundary conditions. in case 1, the base is heated and the two inclined walls are symmetrically cooled, and in case 2, the base is cooled and the two top inclined walls are symmetrically heated. base angles varying from 15 to 75◦have been used for different rayleigh numbers ranging from 103 to 105. yoshio masuda, etc., [12] showed analytically and numerically a double-diffusive natural convection in a rectangular fluid-saturated porous medium. the analysis reveals that there is a range of buoyancy ratios n in which one obtains two types of solutions or oscillating convection. in the case of 0.4 < n < 1.0, there exist two analytical solutions when rc = 100 and le = 30. in that case, two solutions, temperature-dominated and concentration-dominated solutions, are calculated when the aspect ratio is small. 2. mathematical formulation the schematic of the system under consideration is shown in fig (1). the salty water on the bottom side (th) of the glazing enclosure is vaporized from the liquid–vapor interface. the vapor moves through the air and condenses at the cooled side walls (tl). the vertical wall is assumed to be adiabatic and impermeable. the fluid is assumed to be incompressible, newtonian, absorbing , viscous, and two dimensional at steady state conditions. according to the above assumptions, these equations can be written in dimensional form as continuity equation …(1) xmomentum equation …(2) ymomentum equation …(3) energy equation …(4) concentration equation …(5) jasim m. mahdi al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 6582 (2013) 67 the boussinesq approximation for the buoyancy term in the momentum equations have been employed, [ [13]. the use of vorticity–stream function formulation can eliminate pressure gradient terms from momentum equations and simplify the solution procedure. with the stream function, the velocity components u and v and vorticity can be expressed as and then introducing the following dimensionless groups for the governing equations, with with the governing equations in terms of vorticity-stream function form become: stream function equation …(6) vorticity equation …(7) energy equation …(8) concentration equation …(9) where u and v in equations (8-9) is as follow: …(10) the dimensionless parameters appearing in equations (6 – 9) are the prandtl number , α/d, the thermal rayleigh number , the compositional rayleigh number , and . the appropriate boundary conditions in dimensionless form can be formulated as: 1. at the inclined surface (glass cover) 2. at the bottom surface (absorber) 3. at the vertical wall (adiabatic wall) the local heat transfer rates on the surface of heat source and local mass transfer on the surface of pollutant source are defined respectively as and …(11) the average nusselt and sherwood numbers represents the average heat and mass transfer rates on the surface of heat and pollutant sources [4], which are defined respectively as …(12) …(13) 3. numerical technique the central difference scheme used to discretize the system of partial differential equations (6-10) via a finite difference method (fdm). iterative under relaxation method (urm) used to solve the system of new algebraic equations to give approximate values of the dependent variables at a number of discrete points called (nodes) in the computational domain. the computational domain is subdividing in the x and y directions with vertical and horizontal uniformly spaced grid lines to form these nodes. fig (1) grid of 101 × 101 nodes is adopted typically in this study. however, to ensure the accuracy and validity of the numerical schemes, five grid systems, 61×61, 81×81, 101×101, 121×121, and 151×151 are tested. results show the average nusselt number prediction for 101×101 grid points nearly correspond to that obtained from other grid points, the maximum relative error (% є) obtained through the five grid systems is no more than 2% as shown in table (1). the accuracy of the numerical code was assessed by applying it to a case studied by e. fuad kent, etc. [10], who considered a right jasim m. mahdi al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 6582 (2013) 68 triangular enclosure similar to that being considered in this paper, the results in form of streamlines and isothermals contours for ( , and different rayleigh numbers (103105) compared and excellent agreement was observed, figures (2-3) respectively. the convergence criteria employed to terminate the computations and reach the solution were reassigned as (ψζ ψζ-1)/ψζ ≤ 10-6, (θζ θζ-1)/θζ ≤ 10-6, (cζ cζ-1)/cζ ≤ 10-6, and (ωζ ωζ-1)/ ωζ ≤ 106, the indices ζ and ζ −1 represent the current and previous iteration, respectively. table 1, grid independence study results for average nusselt number at (br=0, α = 45°). size 61×61 81×81 101×101 121×121 151×151 % є ra = 103 4.947 4.994 5.197 5.230 5.244 0.9 ra = 104 4.997 5.392 5.486 5.588 5.572 1.85 ra = 105 6.993 7.124 7.211 7.301 7.350 1.92 fig.1 . a schematic of the geometry and grid. y ∆x h l x ∆y jasim m. mahdi al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 6582 (2013) 69 ∆ψ = 0.005 ψ m = 0.105 ∆ψ = 0.1 ψ m = 2.090 ∆ψ = 0.67 ψ m = 13.340 ∆θ = 0.05 θ m = 1.00 ∆θ = 0.05 θ m = 1.00 ∆θ = 0.05 θ m = 1.00 fig. 2. comparison of streamlines inside the right triangular enclosure for rayleigh numbers 103,104 and 105, respectively between (a) kent (b) present study. fig. 3. comparison of isotherms inside the right triangular enclosure for rayleigh numbers 103,104 and 105, respectively between (a) kent (b) present study. (a) (b) ra = 103 ra = 104 ra = 105 (a) (b) ra = 103 ra = 104 ra = 105 ∆ψ = 0.005 ψ m = 0.105 ∆ψ = 0.1 ψ m = 2.090 ∆ψ = 0.67 ψ m = 13.340 ∆θ = 0.05 θ m = 1.00 ∆θ = 0.05 θ m = 1.00 ∆θ = 0.05 θ m = 1.00 jasim m. mahdi al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 6582 (2013) 70 (a) (b) (c) n = -1 ∆ψ = 0.002 ψ m = 0.047 ∆ψ = 0.03 ψ m = 0.610 ∆ψ = 0.33 ψ m = 6.510 n = 0 ∆ψ = 0.001 ψ m = 0.028 ∆ψ = 0.02 ψ m = 0.360 ∆ψ = 0.35 ψ m = 7.060 n = 1 ∆ψ = 0.005 ψ m = 0.101 ∆ψ = 0.4 ψ m = 7.980 ∆ψ = 0.06 ψ m = 1.110 n = 3 ∆ψ = 0.012 ψ m = 0.245 ∆ψ = 0.1 ψ m = 2.020 ∆ψ = 0.46 ψ m = 9.240 n = 5 ∆ψ = 0.019 ψ m = 0.383 ∆ψ = 0.13 ψ m = 2.640 ∆ψ = 0.49 ψ m = 9.880 fig. 4. effect of buoyancy ratio on streamlines at le=2, and for (a) ra=103, (b) ra=104, and (c) ra=105. jasim m. mahdi al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 6582 (2013) 71 (a) (b) (c) n = -1 ∆θ = 0.05 θ m = 1.00 ∆θ = 0.05 θ m = 1.00 ∆θ = 0.05 θ m = 1.00 n = 0 ∆θ = 0.05 θ m = 1.00 ∆θ = 0.05 θ m = 1.00 ∆θ = 0.05 θ m = 1.00 n = 1 ∆θ = 0.05 θ m = 1.00 ∆θ = 0.05 θ m = 1.00 ∆θ = 0.05 θ m = 1.00 n = 3 ∆θ = 0.05 θ m = 1.00 ∆θ = 0.05 θ m = 1.00 ∆θ = 0.05 θ m = 1.00 n = 5 ∆θ = 0.05 θ m = 1.00 ∆θ = 0.05 θ m = 1.00 ∆θ = 0.05 θ m = 1.00 fig. 5. effect of buoyancy ratio on isotherms le=2, and for (a) ra=103, (b) ra=104, and (c) ra=105. jasim m. mahdi al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 6582 (2013) 72 (a) (b) (c) n = -1 ∆c = 0.05 c m = 1.00 ∆c = 0.05 c m = 1.00 ∆c = 0.05 c m = 1.00 n = 0 ∆c = 0.05 c m = 1.00 ∆c = 0.05 c m = 1.00 ∆c = 0.05 c m = 1.00 n = 1 ∆c = 0.05 c m = 1.00 ∆c = 0.05 c m = 1.00 ∆c = 0.05 c m = 1.00 n = 3 ∆c = 0.05 c m = 1.00 ∆c = 0.05 c m = 1.00 ∆c = 0.05 c m = 1.00 n = 5 ∆c = 0.05 c m = 1.00 ∆c = 0.05 c m = 1.00 ∆c = 0.05 c m = 1.00 fig. 6. effect of buoyancy ratio on isoconcentration at le=2, for (a) ra=103, (b) ra=104, and (c) ra=105. jasim m. mahdi al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 6582 (2013) 73 (a) (b) (c) n = -1 ∆ψ = 0.011 ψ m = 0.227 ∆ψ = 0.13 ψ m = 2.550 ∆ψ = 0.59 ψ m = 11.840 n = 0 ∆ψ = 0.005 ψ m = 0.105 ∆ψ = 0.1 ψ m = 2.090 ∆ψ = 0.67 ψ m = 13.340 n = 1 ∆ψ = 0.02 ψ m = 0.406 ∆ψ = 0.17 ψ m = 3.320 ∆ψ = 0.72 ψ m = 14.420 n = 3 ∆ψ = 0.044 ψ m = 0.889 ∆ψ = 0.23 ψ m = 4.530 ∆ψ = 0.65 ψ m = 13.010 n = 5 ∆ψ = 0.063 ψ m = 1.253 ∆ψ = 0.26 ψ m = 5.290 ∆ψ = 0.61 ψ m = 12.220 fig. 7. effect of buoyancy ratio on streamlines at le=2, and for (a) ra=103, (b) ra=104, and (c) ra=105. jasim m. mahdi al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 6582 (2013) 74 (a) (b) (c) n = -1 ∆θ = 0.05 θ m = 1.00 ∆θ = 0.05 θ m = 1.00 ∆θ = 0.05 θm = 1.00 n = 0 ∆θ = 0.05 θ m = 1.00 ∆θ = 0.05 θ m = 1.00 ∆θ = 0.05 θ m = 1.00 n = 1 ∆θ = 0.05 θ m = 1.00 ∆θ = 0.05 θ m = 1.00 ∆θ = 0.05 θ m = 1.00 n = 3 ∆θ = 0.05 θ m = 1.00 ∆θ = 0.05 θ m = 1.00 ∆θ = 0.05 θ m = 1.00 n = 5 ∆θ = 0.05 θ m = 1.00 ∆θ = 0.05 θ m = 1.00 ∆θ = 0.05 θ m = 1.00 fig. 8. effect of buoyancy ratio on isotherms at le=2, and for (a) ra=103, (b) ra=104, and (c) ra=105. jasim m. mahdi al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 6582 (2013) 75 (a) (b) (c) n = -1 ∆c = 0.05 c m = 1.00 ∆c = 0.05 c m = 1.00 ∆c = 0.05 c m = 1.00 n = 0 ∆c = 0.05 c m = 1.00 ∆c = 0.05 cm = 1.00 ∆c = 0.05 c m = 1.00 n = 1 ∆c = 0.05 c m = 1.00 ∆c = 0.05 c m = 1.00 ∆c = 0.05 c m = 1.00 n = 3 ∆c = 0.05 c m = 1.00 ∆c = 0.05 c m = 1.00 ∆c = 0.05 c m = 1.00 n = 5 ∆c = 0.05 c m = 1.00 ∆c = 0.05 c m = 1.00 ∆c = 0.05 c m = 1.00 fig. 9. effect of buoyancy ratio on isoconcentration at le=2, and for (a) ra=103, (b) ra=104, and (c) ra=105. jasim m. mahdi al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 6582 (2013) 76 (a) (b) (c) n = -1 ∆ψ = 0.041 ψ m = 0.830 ∆ψ = 0.25 ψ m = 4.980 ∆ψ = 0.84 ψ m = 16.700 n = 0 ∆ψ = 0.014 ψ m = 0.280 ∆ψ = 0.24 ψ m = 4.730 ∆ψ = 1.02 ψ m = 20.430 n = 1 ∆ψ = 0.052 ψ m = 1.046 ∆ψ = 0.29 ψ m = 5.770 ∆ψ = 1.05 ψ m = 20.910 n = 3 ∆ψ = 0.093 ψ m = 1.854 ∆ψ = 0.33 ψ m = 6.620 ∆ψ = 0.78 ψm = 15.55 n = 5 ∆ψ = 0.119 ψ m = 2.373 ∆ψ = 0.35 ψ m = 7.050 ∆ψ = 0.76 ψm = 15.27 fig. 10. effect of buoyancy ratio on streamlines at le=2, and for (a) ra=103, (b) ra=104, and (c) ra=105. jasim m. mahdi al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 6582 (2013) 77 (a) (b) (c) n = -1 ∆θ = 0.05 θ m = 1.00 ∆θ = 0.05 θ m = 1.00 ∆θ = 0.05 θ m = 1.00 n = 0 ∆θ = 0.05 θ m = 1.00 ∆θ = 0.05 θ m = 1.00 ∆θ = 0.05 θ m = 1.00 n = 1 ∆θ = 0.05 θ m = 1.00 ∆θ = 0.05 θ m = 1.00 ∆θ = 0.05 θ m = 1.00 n = 3 ∆θ = 0.05 θ m = 1.00 ∆θ = 0.05 θ m = 1.00 ∆θ = 0.05 θ m = 1.00 n = 5 ∆θ = 0.05 θ m = 1.00 ∆θ = 0.05 θ m = 1.00 ∆θ = 0.05 θ m = 1.00 fig. 11 .effect of buoyancy ratio on isotherms at le=2, and for (a) ra=103, (b) ra=104, and (c) ra=105. jasim m. mahdi al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 6582 (2013) 78 (a) (b) (c) n = -1 ∆c = 0.05 c m = 1.00 ∆c = 0.05 c m = 1.00 ∆c = 0.05 c m = 1.00 n = 0 ∆c = 0.05 c m = 1.00 ∆c = 0.05 c m = 1.00 ∆c = 0.05 c m = 1.00 n = 1 ∆c = 0.05 c m = 1.00 ∆c = 0.05 c m = 1.00 ∆c = 0.05 c m = 1.00 n = 3 ∆c = 0.05 c m = 1.00 ∆c = 0.05 c m = 1.00 ∆c = 0.05 c m = 1.00 n = 5 ∆c = 0.05 c m = 1.00 ∆c = 0.05 c m = 1.00 ∆c = 0.05 c m = 1.00 fig. 12. effect of buoyancy ratio on isoconcentration at le=2, and for (a) ra=103, (b) ra=104, and (c) ra=105. jasim m. mahdi al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 6582 (2013) 79 -2 -1 0 1 2 3 4 5 6 3 4 5 6 7 8 9 10 buoyancy ratio (n) a ve ra ge n us se lt n um be r ( n u) 30°, ra=103 30°, ra=104 30°, ra=105 45°, ra=103 45°, ra=104 45°, ra=105 60°, ra=103 60°, ra=104 60°,ra=105 -2 -1 0 1 2 3 4 5 6 2 3 4 5 6 7 8 9 10 11 12 buoyancy ratio (n) a ve ra ge s he rw oo d n um be r ( s h) 30°, ra=103 30°,ra=104 30°, ra=105 45°, ra=103 45°,ra=104 45°,ra=105 60°, ra=103 60°, ra=104 60°, ra=105 fig. 13. effect of buoyancy ratio at different (ra) and different ( ), on average nusselt number. fig. 14. effect of buoyancy ratio at different (ra) and different ( ), on average sherwood number. 2 buoyancy ratio (n) 2 buoyancy ratio (n) a ve ra ge n us se lt n um be r ( n u) a ve ra ge s he rw oo d n um be r ( s h) jasim m. mahdi al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 6582 (2013) 80 4. results and discussion numerical analysis of double diffusive laminar natural convection in a right triangular solar collector has been made in current work for different rayleigh numbers ra (103-105), buoyancy ratio n (-1 5), and angle of inclined glass cover with horizontal coordinate (300-600) via finite difference technique. the working fluid inside the cavity was the air, with pr=0.71, and the lewis number was held fixed through this investigation at (le = 2). the numerical results in form of the streamlines, isotherms, isoconcentration, average nusselt, and average sherwood number numbers for various values of the parameters governing the heat transfer and fluid flow will be presented and discussed. indeed, for ( the thermal buoyancy force due to the heat transfer and thermal expansion, (which acts to the upward direction) opposes the buoyancy force due to the mass transfer, (which acts to the downward direction). as a result, there is a very weak flow due to competition between two forces. the fluid moves downward from the upper summit and the flow transforms on one small cell turning from the center to the cold sides brushing against the bottom vicinities. for positive buoyancy ratios (n > 0), the heated flow moves from bottom wall and impinges to the inclined wall and one cell formed in clockwise direction. figures (4,7,10) illustrates the effect of buoyancy ratios on streamlines at different (ra) and different . as rayleigh numbers or buoyancy ratios increases, the rotating cell occupies more space inside the cavity, indicating that the convection currents become more effective and that heat transfer by convection become more predominate. the maximum stream function value is obtained for , ra=105, and ( ). fig (5,8,11) illustrates the isotherms contours at different rayleigh numbers and different buoyancy ratios. one can observe that the patterns of the isotherms contours are related to the buoyancy ratio values and rayleigh numbers. obviously, the convection effects are more effective at the positive buoyancy ratios. it should also be noted that when the buoyancy ratios or rayleigh numbers increases, the temperature field develops quickly. in comparison, for negative buoyancy ratios values, one can observe a kind of stratification indicating the conductive regime domination. isoconcentration contours at different rayleigh numbers and different buoyancy ratios are illustrates in figures (6,9,12). distribution of isoconcentration contours reveal a similar distribution with distribution of isotherm contours. both rayleigh numbers and buoyancy ratio have a strong influence on the streamlines patterns, isotherms, isoconcentration, and enhance the flow strength. figures (13,14) illustrates the effect of increase in rayleigh numbers and angle of inclined glass cover with horizontal coordinate at different buoyancy ratios on the average nusselt number and average sherwood number, respectively. for negative buoyancy ratios the values for average nusselt number and average sherwood number decreases. by contrast, for positive buoyancy ratios , the values for average nusselt number and average sherwood number increases when the rayleigh numbers and buoyancy ratios increases. 5. conclusions the results of the present study lead to the following conclusions: • the results show that both rayleigh number and buoyancy ratio have a strong effect on the streamline patterns, isotherms, and isoconcentration. • results show that a decrease in the angle of inclined glass cover with horizontal coordinate ( leads to increase average nusselt number and average sherwood number. • for (n > 0), both average nusselt number and average sherwood number increase with increasing of buoyancy ratio and rayleigh number. by contrast for ( these values decreases. also, increasing of the buoyancy ratio for positive values (n > 0), at the same rayleigh number enhance the heat and mass transfer rate. nomenclature h solar collector height (m) l solar collector length (m) n buoyancy ratio c dimensional species concentration c dimensionless species concentration d species diffusivity (m2 kg-2 s-1) g gravitational acceleration (m s-2) le lewis number nu average nusselt number p dimensional pressure jasim m. mahdi al-khwarizmi engineering journal, vol. 9, no. 4, p.p. 6582 (2013) 81 p dimensionless pressure pr prandtl number ra rayleigh number sh average sherwood number t wall temperature (k) u, v dimensional velocity components (m s-1) u, v dimensionless velocity components x, y dimensional coordinates (m) x, y dimensionless coordinates greek symbols thermal diffusivity (m2 s-1) expansion coefficient (k-1) kinematic viscosity (m2 s-1) dimensionless temperature density (kg m-3) dimensional vorticity dimensionless vorticity dimensional stream function ψ dimensionless stream-function ∆ laplacian in cartesian coordinates angle of inclined glass cover with horizontal coordinate superscripts ζ current iteration number ζ-1 previous iteration number subscripts h high low h hot l cold t thermal t c fluid at the bottom surfaces references [1] hitesh n panchal, dr. p. k. shah, [effect of varying glass cover thickness on performance of solar still in winter climate conditions], international journal of renewable energy research, vol.1, no.4 (2011) 212-223. 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[12] yoshio masuda, michio yoneya, and shinichi sumi, [double-diffusive natural convection in a porous medium under constant heat and mass fluxes], heat transfer—asian research, vol. 28 (1999), 255–265. [13] mohamed a. teamah, [double-diffusive laminar natural convection in a symmetrical trapezoidal enclosure], alexandria engineering journal, vol. 45, (2006), no. 3, 251-263. ���� ���ي �� � ��� 4، ا���د��9 � ا���ارز�� ا���� �� ا���� ،82 -65 )2013( 82 � 0 / ش�-� ���, +� ا*()'�ر &��%� ا�$#�"� ا��! � �� ��د�� درا� %�" �� ا�2او � ��-3 رش *�� ���� ���ي�** � ***&��! 5�رث � *،** �� ��اد / ���� ا������ / ��� ھ���� ا��� �� ! ��اد / ���� ا������ ا�&%ارز " **� �� ! jasim_ned@yahoo.com : ا.�-,)و*" ا�()'�* ali_mohsen7788@yahoo.com : ا.�-,)و*" ا�()'�** thamir.2008@yahoo.com : ا.�-,)و*" ا�()'�*** �� ا��6 1" ا.*,9 ر 8" 647 �45" 2�3 � �1 ا�0او'/��: "� و�/� 8ُ/)َض :(/ ت در!/� ا�;/)ارة وا�,)��/0 �-/> . 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ا��%ا > ا=`ه �� a1 � و�� أظ�)ت ا��, e�%,4ور�� �5)وود ا� t��* .6/474ا� </� ن زوا's?* ��= e�%,4ور�� �5)وود ا� e�%,4ا� t��* ��دة 8" ر 8� . اظ�)ت ا��, a1 ز'/fأ o/ذ� v/دة ،ا� /'0� %nا�� �)�*(n > 0) %/nا�� r��� k-�� �و�/o�c ان ا�0'/ دة r/�* "/8 . )ور�� را'�" ا�;)اري '0داد ر�� *��t ا�e�%,4 ور�� �5)وود ا�e�%,4 و %nى ا��%�(n > 0) ��,-ل ا�;)ارة وا� �?� و�/� اظ�/)ت ا��,/ q a1%اs/8 !�/� و�� �q ا�4? ر*� 6 *, a1. و�)�� را'�" j)اري واg�;ُ' �j ��ل ا*,? ا�;%ث ا��/ ث ا�9�4%رة;� . 6 ا. احمد محمد الغبان al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 8, no. 3, p.p. 94-100 (2013) یتانیوم المنجز باالفالم الرقیقةتأثیر زیادة نسبة الكاربون على الخواص المیكانیكیة لكاربید الت احمد محمد حسن الغبان لتكنولوجیةالجامعة ا /قسم ھندسة المواد ahmed_gaban@yahoo.com :البرید االلكتروني (received 12 march 2012; accepted 18 feburary 2013) ةالخالص افة اضمثل الصالدة ممتازة من مواد كاربیدیة او نایتریدیة ذات اھمیة فائقة في مجال الصناعة لما لھا من خواص میكانیكیة كونةمال تمثل االفالم الرقیقة الكاربون على الخواص المیكانیكیة ةدراسة تاثیر نسب تفي ھذا البحث تم. الى امكانیة الطالء بدرجات حراریة واطئة تخدم السطوح الحساسة لدرجات عالیة لوحظ ان ھنالك وقد .كیمیاویةمن التراكیب ال معین ممثلة بمعامل المرونة الفالم رقیقة من كاربید التیتانیوم المنتج بواسطة التذریة المغنترونیة لمدى حیث ان الطورالناتج ھو في الغالب لكاربید التیتانیوم بغض النظرعن نسبة الكاربون من ھ الناتج مع نسبة الكاربون المضافاستقراریة للخواص البنیویة للطور ) تزداد الصالدة( حیث تزداد الخواص المیكانیكیة . كاربونلوحظ ارتباط الخواص المیكانیكیة للطورالكاربیدي بنسبة ال%. ٦٥الى غایة اقل من % ٣٤حدود قد تشیر ھذه النتائج الى عالقة وثیقة بین الخواص البنیویة. وثم تبدا بالتناقص بنسب كاربون اعلى% ٥٠للطورالمنتج لغایة نسبة كاربون بمقدار )microstructure( م الناتج من جھة ثانیةوالمیكانیكیة من جھة وبین االجھادات المتبقیة في الفل. .، المعاملة الحراریة، قیاس التغلغل النانويالتیتانیوم، التذریة المغنترونیةرقائق كاربید : الكلمات المفتاحیة المقدمة .١ تعد كاربیدات المعادن االنتقالیة مثل كاربید التیتانیوم او كاربید ا من ناحیة اذ انھ الفائقة الخواصالتنكستن من المواد الصناعیة مقاومة لدرجات الحرارة العالیة و مقاومة ( حراریا وكیمیائیا جیدة اضافة الى خواصھا المیكانیكیة العالیة من ناحیة اخرى) للتأكل ھذه المواد تجمع في العادة بین خواص المواد المعدنیة من . ]١[ خواص عالوة علىجھة كالتوصیلیة الكھربائیة والحراریة العالیة د السیرامیكیة كمقاومة البلى ودرجة االنصھار العالیة من الموا كثیرا ما یستخدم كاربید التیتانیوم كطالء واقي .]٢[جھة اخرى على سطوح المواد المعدنیة بالنظر لما یمتاز بھ من خواص كما مقاومة لالحتكاك تجعلھ في المقدمة لمقاومة البلى المیكانیكي كذلك تستخدم في . مل الكرویة ھو الحال في عدد القطع والحوا طالء الحاویات المقاومة لدرجات الحرارة العالیة او التي تستخدم . ]١,٢,٣[في حفظ منصھرات المعادن وتطبیقات اخرى كثیرة وسائل متعددة تستخدم للطالء بكاربید التیتانیوم ولكن اكثر الطرق )pvd(الحدیثة المستخدمة في ھذا المجال ھي الترسیب الفیزیائي اذ انھ یمكن بواسطة ھذه .]٤,٣[) cvd( والترسیب الكیمیائي التقنیات طالء اغلب سطوح المواد الھندسیة وخصوصا السطوح الحساسة لدرجات الحرارة العالیة كاغلب انواع الصلب وسبائكھ وفي ھذا المجال یمتاز الترسیب الفیزیائي بكافة تقنیاتھ اذ . ]٤[ رجات واطئة وامكانیة السیطرة على یجمع بین خاصیة الطالء بد یحافظ كاربید التیتانیوم على .]٤[التركیب الكیمیاوي للكاربید بنیتھ الذریة لمدى من التراكیب الكیمیاویة من التیتانیوم والكاربون وكما ھو معلوم فان العالقة بین . ]٥[وحسب مخطط االتزان القة وثیقة التركیب الكیمیاوي للمادة والخواص البنیویة ھي ع لم . الخواص الفیزیائیة والمیكانیكیة یمكن ان تؤثر على مجمل تدرس ھذه العالقة بشكل مستفیض من قبل الباحثین المھتمین بالموضوع ولكن تم التركیز في الغالب على التركیب الكیمیاوي التیتانیوم الى الكاربون ةالقریب الى التجانس حیث تكون نسب من ھنا تبرز اھمیة دراسة .]٥[ وي واحدیسا c/ti حیث متعادلة تاثیر التركیب الكیمیاوي لكربید التیتانیوم على مجمل خواص ھذه تم تشكیل سلسلة من االفالم في ھذا البحث . المادة الھندسیة الفائقة الرقیقة لكاربید التیتانیوم المختلف في التركیب الكیمیاوي من لم تظھر . c/ti=65%الى غایة c/ti=34%حدود نسبة النتائج اي اختالف في البنیة البلوریة على طول المدى المختلف تزداد . للتركیب الكیمیاوي ما عدا اختالف في اتجاه النمو البلوري تزداد الخواص المیكانیكیة . االبعاد الذریة مع زیادة نسبة الكربون مع زیادة نسبة الكربون " eیونك " للطور الناتج ممثلتا بمعامل ثم تبدا بالتناقص مع استمرار الزیادة بنسبة c/ti=1لى غایة ا تكون اجھادات داخلیة ضغطیة الكربون مما یعطي دلیل على .المنتج للغشاء الرقیق تؤدي الى تراجع في الخواص المیكانیكیة الجزء العملي .٢ في ھذا البحث تم استخدام نفس حجرة الضغط المذكورة في -الطالء من قبل الباحث في جامعة اخن اذ صممت منظومة . ]٦[ المانیا ونفذت وفق متطلبات انتاج افالم مختلفة التركیب الكیمیاوي كدفعة واحدة باستخدام التذریة المغنترونیة . combinatorial magnetron sputtringاالندماجیة mailto:ahmed_gaban@yahoo.com )2013(-100 94 ، صفحة1، العدد9مجلة الخوارزمي الھندسیة المجلد عبد الكاظم احمد محمد حسن 95 استخدمت اقطاب من كل من التیتانیوم والكاربون الصلب العالي درجة ١٤ن عن السطح الواقع في االسفل مقداره النقاوة وبمیال ھذا المیالن یعطي االمكانیة للتحكم . ١ -كما موضح في الشكل قطبا الكاربون . بمدى كبیر من التراكیب الكمیاویة لنفس المكونات ملیمتر ویبعدان عن السطح ٣ملیمتر وسمك ٣٩والتیتانیوم بقطر ح المستقبل عبارة عن السط. ملیمتر ٥٠المستقبل للغشاء بحدود رقاقة من اوكسید االلمنیوم عالي النقاوة بسطح صقیل واحد وبقطر تم وضع رقاقة مثقبة من الصلب فوق السطح . ملیمتر ٥٠.٨ المستقبل لغرض حجز الطالء عن مناطق محددة والنتاج عدة كل مساحة دائریة تمثل تركیب . ٢مساحات دائریة حسب الشكل عن االخر باالتجاه من الیمین الى الیسار كیمیاوي محدد مفصول بعد اكمال ). تیتانیوم او كاربون( او العكس وحسب جھة كل قطب وضع السطح المستقبل للطالء واالقطاب في اماكنھا یتم تفریغ باسكال للتخلص من ١٠-٤الحجرة من الھواء لغایة ضغط مقداره . اسكالب ٠.٣اغلب الشوائب بعد ذلك یضخ غاز االركون بضغط واط لكل سنتیمتر مربع لكل ٦.٧و ٤.٢تم تسلیط طاقة مقدرھا من قطبي التیتانیوم والكاربون على التوالي لیتم انتاج البالزما الطالء او الترسیب تم بدون اي مصدر حراري . الالزمة للطالء لتسخین السطح المستقبل للطالء ولم ترتفع درجة حرارة السطح بعد انجاز الطالء بسمك . ئویة في الغالبدرجة م ٥٠عن اكثر من میكرون توقف المنظومة لیتم استخراج السطح ١.٥یقارب المستقبل للغشاء الرقیق ویتم تقطیع العینة لعدة اجزاء من االسفل الى االعلى للحصول على شرائح متعددة كل شریحة تحتوي عدة ي ف. مساحات دائریة وكل مساحة تمثل تركیب كیمیاوي مختلف عینة كما ١٣ھذا البحث استخدمت شریحة واحدة فقط حاویة على تم فحص التركیب الكیمیاوي لكل مساحة . ٢موضح في الشكل المربوط یاباني المنشأ edxدائریة في الوسط بواسطة جھاز لمجھر الكتروني ماسح والمتواجد في قسم كیمیاء المواد في جامعة لغرض المعایرة من مادة استعملت عینة قیاسیة. المانیا-اخن البنیة البلوریة تم فحصھا لكل . كاربید التیتانیوم لغرض المقارنة ھذا . gaddsمنطقة في الشریحة بواسطة اشعة اكس بجھاز الجھاز یعطي امكانیة كبیرة لفحص االفالم الرقیقة بزاویة حیود واحدة وباالمكان تدویر العینة بكافة االتجاھات للحصول على اما الخواص المیكانیكیة متمثلة . تیجة لحیود االشعة السینیةافضل ن بمعامل یونك لكل مساحة صغیرة فلقد تم احتسابھا بعد الحصول على النتائج التفصیلیة من جھاز قیاس الخواص المیكانیكیة النانوي the nanoindentation measurements . اذ یتم ادخال ثم تثبت النقاط المراد فحصھا الشریحة بعد تثبیتھا على حامل ومن وتاخذ عدة نقاط لكل مساحة دائریة لغرض احتساب معدل القراءة .لكل مساحة طالء e “یونك “ومن ثم یستخرج معامل التذریة المغنترونیة لكاربید التیتانیوم من قطبي الكاربون والتیتانیوم. ١-شكل magnetron sputtering of ticx from carbon and titanium cathodes. .الغشاء الرقیق من كاربید التیتانیوم بمساحات دائریة بعد عملیة الطالء على سطح من اوكسید االلمنیوم -٢-الشكل the deposited ticx thin films with circular shapes on a al2o3 substrate. )2013(-100 94 ، صفحة1، العدد9مجلة الخوارزمي الھندسیة المجلد عبد الكاظم احمد محمد حسن 96 النتائج والمناقشة .٣ تراكیب الكیمیاویة لمساحات بعض نتائج الیوضح ٣-الشكل الكاربون الى اقص نسبةمن خاللھا یمكن مالحظة تن. طالء مختلفة في الجھة القریبة الى قطب التیتانیوم في c/ti ratioالتیتانیوم ھذه .حین تزداد ھذه النسبة في حال القرب من قطب الكاربون التذریة المغنترونیة احدى اھم المیزات التي توفرھا طریقة في عدة . combinatorial magnetron sputtringاالندماجیة ابحاث سابقة اظھر كاربید التیتانیوم المرسب كاغشیة رقیقة ھذا یعطي . ]٧,٨,٩,١٠[امكانیة عالیة للتحكم بالتركیب الكیمیاوي االمكانیة الجراء دراسات نظامیة تحلیلیة لربط التركیب الكیمیاوي اص الفیزیائیة والمیكانیكیة وبامكانیة مع كافة الخوللطور المنتج عدم نظرا ل bulk materialغیر ممكنة في حالة العینات الكتلویة بتقنیة المساحیق على انتاج مجموعة كبیرة من العیناتامكانیة وللصعوبة في تكرار نفس الظروف المحیطة في كل سبیل المثال لما مجموعةالفحص باالشعة السینیة یوضح نتائج ٤الشكل .حالة تظھر النتائج بروز كاربید . یب الكیمیاويمختلفة الترك عینة ١٣ التیتانیوم كطور وحید على الرغم من اختالف التركیب الكیمیاوي او نسبة الكاربون الى التیتانیوم صعودا او نزوال برغم اختالف یمكن ایضا . واضح في شدة الطور الناتج بزیادة نسبة الكاربون . واسع في اتجاه نمو البلورات بزیادة نسبة الكاربونمالحظة فرق (النظام المكعب في) ١ ١ ١( بلورات باالتجاهللحیث یتجھ النمو مع ) 0 0 2( بلوري نمو باتجاهالالى ) نسبة الكاربون االقل في البنیة anisotropyموضوع التباین .انخفاض نسبة الكاربون تركیب قد تم مناقشتھا في المجھریة الفالم رقیقة ذات نفس ال لم یتم توضیح السبب الرئیسي . ]١١,١٢,١٣,١٤[ابحاث سابقة لھذه الظاھرة وسبب اختالفھا من طریقة انتاج الى اخرى غیر ان the strain energyالسبب العام یمكن اجمالھ في طاقة االنفعال في حالة ) ١١١(تتجھ البلورات باتجاه نمو بعبارة اخرى . ]١٤[ في ة تیتانیوم اكبر لغرض تقلیل الجھد الالزم للبناء البلوري نسب بزیادة نسبة الكربون في ) 0 0 2(الى البلوري حین یتجھ النمو سوف یتم التطرق الى ھذه النتائج بصورة تفصیلیة . الطور المنتج تم . اكثر في ابحاث مستقبلیة الحقة لغرض دراستھا بشكل تفصیلي حث التركیز على العالقة بین نسبة الكاربون الى في ھذا الب التیتانیوم في الطور الكاربیدي المنتج وبین الخواص المیكانیكیة فقد تم دراسة الخواص المیكانیكیة بواسطة . متمثلة بمعامل المرونة جھاز الفحص النانوي بدقة متناھیة لغرض تجاھل خواص المادة یوضح ٥ -الشكل. لمنیوماالساس متمثلة في رقیقة اوكسید اال العالقة بین نسبة الكاربون الى التیتانیوم في الطور الناتج ومعامل یمكن . المرونة المستحصل من فحص الخواص المیكانیكیة مالحظة ان معامل المرونة یزداد طردیا بزیادة نسبة الكاربون الى وحدة ذریة للكاربون في حین تبدأ قیمة % ٥٠غایة ما مقداره مل المرونة باالنخفاض تدریجیا بزیادة نسبة الكاربون اكثر من معا قد یعود السبب الرئیسي %. ٦٣الى غایة حدود اقل من % ٥٠ لزیادة الخواص المیكانیكیة في الطور الناتج مع زیادة نسبة الكاربون الى تزاید اعداد ذرات الكاربون التي تحتل المواقع ما ھذا النوع من التداخل الذري .interstitial atomsبین الذرات من المفترض . یتسبب في زیادة ملحوظة في الخواص المیكانیكیة بظھور طور % ٥٠الكاربون الفائض بنسبة اكبر من ان یتسبب وفقا للفحص باالشعة . ]١٥[الكرافیت الحر في البنیة الذریة للمنتج فق للطور السینیة لم یظھر اي دلیل على وجود طور اخر مرا یعطي سببا واضحا للتناقص في الخواص اربیدي الناتج مما الك من ذلك یمكن %. ٥٠المیكانیكیة بزیادة نسبة الكاربون اكثر من االعتقاد بان السبب الرئیسي النخفاض معامل المرونة في الغشاء الرقیق المنتج بنسبة كاربون عالي یمكن ارجاعھ الى االجھادات عتبار ان الغشاء مع االخذ بنظر اال. یبالداخلیة الناتجة اثناء الترس مما قد . تم ترسیبھ دون اي مصدر حراري خارجي الرقیق المنتج یعطي المجال الواسع لالجھادات المرافقة للعب دور اساسي في لوحظ في دراسات سابقة وجود عالقة وثیقة . ]١٦[ ھذه العملیة اذ . ]١٧[ونة بین االجھادات المتكونة في الفلم الرقیق ومعامل المر تتناقص الخواص المیكانیكیة ممثلتا بمعامل المرونة مع زیادة حجم من ھذا یمكن االعتقاد ان . االجھادات المتبقة المرافقة للترسیب سبب التناقص في الخواص المیكانیكیة المرافق لزیادة نسبة الكربون في الغشاء الكاربیدي في ھذا البحث یعود الى االجھادات یمكن االستنتاج ان .]١٨[كما وجد في ابحاث سابقة الضغطیة االجھادات الضغطیة المتولدة نتیجة ظاھرة المزدوج الحراري لھا .الرقیقاثر كبیر في خفض الخواص المیكانیكیة للغشاء االستنتاجات .٤ على الخواص دراسة تاثیر نسبھ الكاربون تفي ھذا البحث تم الفالم رقیقة من كاربید )e( نةالمیكانیكیة ممثلة بمعامل المرو التیتانیوم المنتج بواسطة التذریة المغنترونیة لمدى من التراكیب لوحظ ان ھنالك استقراریة للخواص البنیویة للطور . الكیمیاویة في الغالب اذا انھ نسبة الكاربون المضافة اختالف الناتج مع % ٣٤دود كاربید التیتانیوم بغض النظرعن نسبة الكاربون من ح الخواص المیكانیكیة ترتبط%. ٦٥الى غایة اقل من تزداد لغایة نسبة كاربون اذ للطورالكاربیدي بنسبة الكاربون یستنتج من . وثم تبدا بالتناقص بنسب كاربون اعلى% ٥٠بمقدار ھذا البحث ان االجھادات الضغطیة المتولدة في الفلم الكاربیدي .الخواص المیكانیكیة بصورة فعالةالرقیق لھا اثر كبیر في خفض )2013(-100 94 ، صفحة1، العدد9مجلة الخوارزمي الھندسیة المجلد عبد الكاظم احمد محمد حسن 97 .التركیب الكیمیاوي لعینتین من كاربید التیتانیوم وھي العینات الطرفیة الحاویة على اعلى واقل نسبة كاربون -٣-الشكل the chemical composition of the slide edges of the largest and smallest carbon concentration. .عینة وحسب التركیب الكیمیاوي لنسبة الكاربون ١٣نتائج فحص التركیب البلوري لكاربید التیتانیوم المنتج كافالم رقیقة لما مجموعھ -٤-الشكل the xrd results for ticx thin films of 13 different chemical compositions. a b c d )2013(-100 94 ، صفحة1، العدد9مجلة الخوارزمي الھندسیة المجلد عبد الكاظم احمد محمد حسن 98 لخواص المیكانیكیة الفالم رقیقة من كاربید التایتانیوم وحسب نسبة الكاربون الى التیتانیوم لكل فلم مقارنة مع بعض االبحاث نتائج فحص ا -٥-الشكل .السابقة the mechanical properties of ticx thin films as a function of chemical composition and the comparison with other studies. ادرالمص .٥ [1] j. solda´n, j. musil, “structure and mechanical properties of dc magnetron sputtered tic/cu films", vacuum, vol. 81, pp. 531–583, 2006. [2] m. t. hosseinnejad, z. ghorannevis , m. ghoranneviss, m. soltanveisi, m. shirazi, " preparation of titanium carbide thin film using plasma focus device", j fusion energ, vol 30, pp. 516–522, 2011. [3] k. polychronopoulou, j. lee, c. tsotsos, n.g. demas, r.l. meschewski, c. rebholz, a.a. polycarpou," deposition and nanotribological characterization of sub100-nm thick protective ti-based coatings for miniature applications", tribol lett, vol. 44 pp. 213–221, 2011. [4] e. coronel, u. wiklund, e. olsson," the effect of carbon content on the microstructure of hydrogen-free physical vapour deposited titanium carbide films", thin solid films vol. 518 pp. 71–76, 2009. [5] ya-feng yang, hui-yuan wang, jin-guo wang, and qi-chuan jiang," lattice parameter and stoichiometry of ticx produced in alloyed ti–c systems by selfpropagating high-temperature synthesis", j. am. ceram. soc., vol. 11, pp. 3813–3816, 2008. [6] a. abdulkadhim, t. takahashi, d. music, f. munnik, j. m. schneider," max phase formation by intercalation upon annealing of ticx/al (0.4 ≤ x ≤ 1) bilayer thin films", acta materialia, vol. 59, pp. 6168–6175, 2011. )2013(-100 94 ، صفحة1، العدد9مجلة الخوارزمي الھندسیة المجلد عبد الكاظم احمد محمد حسن 99 [7] d. galvan, y.t. pei, j.th.m. de hosson," influence of deposition parameters on the structure and mechanical properties of nanocomposite coatings ", surface and coating technology, vol. 201, pp. 590-598, 2006. [8] a. leonhardtu, h. liepack, k. bartsch," cvd of ticx /a-c-layers under d.c.-pulse discharge", surface and coatings technology, vol. 133-134, pp. 186-190, 2000. [9] e. kusano, a. satoh. m. kitagawa. h. canto, a. kinbara," titanium carbide film deposition by dc magnetron reactive sputtering using a solid carbon source", thin solid films, vol. 343-344, pp. 254-256, 1999. [10] a.a. voevodin, j.s. zabinski," loadadaptive crystalline–amorphous nanocomposites", journal of materials science, vol. 33, pp. 319327, 1998. [11] r.s. rawat, p. leeb, t. white, li ying, s. lee," room temperature deposition of titanium carbide thin films using dense plasma focus device", surface and coatings technology, vol.138, 159-165, 2001. [12] p. j. martin, r. p. netterfield, t. j. kinder," deposition of tin, tic, and ti02 films by filtered arc evaporation", surface and coatings technology, vol. 49, pp. 239-243, 1991. [13] r. kuzel, jr., r. cernf, v. valvoda, m. blomberg, m. merisalo, s. kadlec," complex xrd microstructural studies of hard coatings applied to pvddeposited tin films part ii transition from porous to compact films and microstructural inhomogeneity of the layers", thin solid films, vol. 268, pp. 72-82, 1995. [14] u.c. oh, j. ho je," effects of strain energy on the preferred orientation of tin thin films", j. appl. phys., vol. 74, pp. 16921698,1993. [15] g.li, l.f.xia," structural characterization of ticx films prepared by plasma based ion implantation", vol. 396, pp. 16-22, 2001. [16] a. kinbara, s. baba," internal stress and young's modulus of tic coatings", thin solid films, vol. 107, pp. 359-364, 1983. [17] c.t. chuanga, c.k. chaob, r.c. changa, k.y. chub," effects of internal stresses on the mechanical properties of deposition thin films", journal of materials processing technology, vol. 2 0 1, pp. 770–774, 2 0 0 8. [18] h. liepack, k. bartsch, w. bru¨ckner, a. leonhardt," mechanical behavior of pacvd tic–amorphous carbon composite layers", surface and coatings technology, vol. 183, pp. 69–73. 2004. ahmed m. h. abdulkadhim al-khwarizmi engineering journal, vol. 9, no.1, p.p. 94-100 (2013) 100 the effect of increasing carbon concentration increasing on the mechanical properties of ticx thin films ahmed m. h. abdulkadhim al-ghaban department of materials engineering/ university of technology ahmed_gaban@yahoo.com mail:-e abstract carbides or nitrides thin films present materials with good mechanical properties for industrial applications as they can be coatings at low temperatures serve temperature sensitive surfaces. in this work the effect of the c percentage on the mechanical properties represented by the young modulus (e) of combinatorial magnetron sputtered ticx (34%x 65%) has been studied. the structure of the produced films is tic independent on the c concentration. the mechanical properties are increased with increasing the c concentration up to 50%, and then decreasing with further c % increasing. these results can be explained by considering the resultant residual stresses. mailto:ahmed_gaban@yahoo.com امنة al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 7, no. 4, pp1-16 (2011) path planning control for mobile robot nabeel k. abid alsahib amenah a.h. salih department of mechatronics engineering/ al-khwarizmi college of engineering/university of baghdad email:dr-nabeelalsahib@hotmal.com (received 16 february 2011; accepted 20september 2011) abstract autonomous motion planning is important area of robotics research. this type of planning relieves human operator from tedious job of motion planning. this reduces the possibility of human error and increase efficiency of whole process. this research presents a new algorithm to plan path for autonomous mobile robot based on image processing techniques by using wireless camera that provides the desired image for the unknown environment . the proposed algorithm is applied on this image to obtain a optimal path for the robot. it is based on the observation and analysis of the obstacles that lying in the straight path between the start and the goal point by detecting these obstacles, analyzing and studying their shapes, positions and points of intersection with the straight path to find the nearly optimal path which connects the start and the goal point. this work has theoretical part and experimental part. the theoretical part includes building a matlab program which is applied to environment image to find the nearly optimal path .matlab c++.net interface is accomplished then to supply the path information for c++.net program which is done for programming the pioneer mobile robot to achieve the desired path. the experimental part includes using wireless camera that takes an image for the environment and send it to the computer which processes this image and sends ( by wireless connection ) the resulted path information to robot which programmed in c++.net program to walk according to this path. so, the overall system can be represented by: wireless camera – computer – wireless connection for the mobile robot . the experimental work including some experiments shows that the developed mobile robot (pioneer p3-dx ) travels successfully from the start point and reach the goal point across the optimal path (according to time and power) which is obtained as result of the proposed path planning algorithm introduced in this paper. keywords:path planning algorithms, pioneer p3-dx mobile robot, image processing, minimum time and power. 1. introduction mobile robots must know where they are and specify a suitable path to the goal to navigate reliably in indoor environments; this is the task of navigation and path planning to enable the robot to reach the goal point with optimal path without any knowledge about the environment, by using wireless camera as feedback sensor. so it is obvious that an efficient control of the mobile robot needs: • a local level based completely on the information of different sensors covering the close circle of the robot. • a high-level for path planning using a global description of the world with possibly incomplete and/or imperfect knowledge. this allows having a safe navigation to modulate continuously the path and eventually to update the map. this work deals with global path planning in which the robot is sent to completely unknown environment (unknown environment's dimensions, obstacle's shape, position and dimension, number of obstacles, distribution of obstacles or any other information), and as soon as the robot reachs to this environment, a wireless camera will send it information as an image by wireless connection to mailto:email:dr-nabeelalsahib@hotmal.com nabeel k. abid alsahib al-khwarizmi engineering journal, vol. 7, no. 4, pp 1 -16 (2011) 2 computer, the computer finds the required path and the information of this path will send to the robot to do it's task to reach the goal point in an approximately optimal path [1]. 2. pioneer mobile robot the platform used in work is pioneer3 dx which is a family of two wheels mobile robots, the newest pioneer3 dx is used for university research and the platform shares a common architecture and foundation with all other mobile robot platforms including amigobot™, peoplebot™ v1, performance peoplebot™ and powerbot™ mobile robots. the robot is built completely with a strong aluminum body; a balanced drive system (twowheel differential with free caster wheel), reversible dc motors, motor-control and drive electronics, high-resolution motion encoders, and battery power, all are managed by an onboard microcontroller and mobile-robot server software. the software includes foundation advanced robotics interface for applications (aria) and ar networking pioneer3 robot has a variety of expansion power and i/o ports for attachment and close integration of a client pc, sensors, and a variety of accessories, all are accessible through a common application interface to the robot’s server software [2]. the mobile platform robot (pioneer3 dx) used is shown in figure (1). fig.1. pioneer mobile robot [2]. 3. oac path planning algorithm this work present an algorithm for planning the path for the robot which is based on detailed analysis and observation of the obstacles lying in the supposed straight line path between start and goal point. when the robot detect on obstacle in its straight direction, the path will be out of this direction and it tends to turn around the obstacle (either clockwise or counterclockwise) until it reach the straight direction again. the phenomena that the path follows it to achieve this movement result from observing the obstacle shape, its dimensions and the points of intersection with straight direction that connects start and goal point. this comes from detailed analysis for these obstacles and all possible cases of intersection that could be found the upper and lower forms of paths. this phenomenon is based on the observation, analysis and conclusion, we can call the algorithm proposed here and which depends on the principles the observation, analysis and conclusion based algorithms. for this reason this algorithm can be called (oac) algorithm according to the first letters of its principles. 4. oac algorithm explanation and definition in this research, it is intendended to find the optimal or nearly optimal path that connects the start and goal point without collision with the obstacles which are found in its direction .if we suppose that there is no obstacle in the straight direction between the start and goal points the path will be purely straight line as shown in fig. (2-a). if an obstacle is located between the start and goal points, it will intersect with this straight line. at this point this straight path must change its direction in order to avoid collision with the obstacle, this is done by making the path turning around the obstacle (adjacently with edges either clockwise or counter clockwise) until it exceeds the obstacle and return again to its straight direction towards the goal point , this behavior is always repeated with any other obstacle located an its straight direction . finally two paths resulted from this behavior: the upper path : is the path that resulted as a combination between two merged paths, the first one is represented by a straight line (in the no obstacle area) and the other represents the surrounded part of the path that is surrounding the obstacles in clockwise manner as shown in figure(2-b). nabeel k. abid alsahib al-khwarizmi engineering journal, vol. 7, no. 4, pp 1 -16 (2011) 3 the lower path : is the path resulted as a combination between two merged paths, the first one is represented by a straight line (in the no obstacle area) and the other represents the surrounded part of the path that is surrounding the obstacles (in the area that contains obstacles) in counter clockwise manner as shown in fig. (2-c ). (a) the supposed straight line b) the upper path (c) the lower path (d) modified upper path (e) intermediate lower (f) modified lower path path fig .2. all the possible paths. note: red point represents the start point. blue point represents the goal point. black rectangular represents the obstacle. red area represents the clearance (explained later). yellow circle represents the robot radius. as shown in figures (2-b, c), the upper and lower paths are not the optimal path. in order to find the optimal path, we follow the following steps: • categorize the indiviual lines that form the upper and lower paths into two groups: group a: it is the group of all segments (individual lines) of the upper or lower path found from straight line equation (the parts of the path in space or for obstacles area). group b: it is the group of all segments (individual lines) of the upper or lower path forming a surrounded path around the obstacles. • finding the resultant: if any line from group a is followed by a line (or successive lines) from group b, they will be replaced by the resultant of them. in opposite, if any line (or successive lines) from group b is followed by any line from the group a, they will be replaced by the resultant of them. • finding tested path: it is the path that results from finding successive resultants for each nline (from the upper or lower paths), so the tested path is combined from these individual resultants. this path is called according to (oac) algorithm the tested path because it must submit to a specific test to judge if it is the optimal ,nearly optimal or not. an important condition must be satisfied when finding each individual resultant that it must be checked (according to environment's image), if there is an obstacle intersects with it on or not. the specific test is summarized in the following stages: • if there is an obstacle in the direction of the resultant, this resultant must resolved to its original components, these components are recognized as forbidden lines (referring to its inability to be replaced with its resultant). • if the direction of this resultant is freeobstacle this resultant is kept and takes its position in the tested path and it is known as unforbidden lines. • the resulted path from step 1 and 2 can be retested again by finding the resultant for only unforbidden lines (while keeping forbidden lines). • step 3 continues until there is no resultant to be found (mostly this occurs one or two times). finally, we will get two new paths, the first resulted from the upper path which is called modified upper path and the other resulted from the lower path which is called modified lower path. these two paths with addition to original upper and lower path and all the resulted intermediate paths are examined and the results of the examination are compared with each other in order to determine the optimal path. nabeel k. abid alsahib al-khwarizmi engineering journal, vol. 7, no. 4, pp 1 -16 (2011) 4 for example, the upper and the lower paths which are shown in fig. (2-b, c) are submitted to the previous test. so, the upper path will converted into modified upper path as shown in fig. (3-d) and the lower path will be converted into intermediate lower path and then into amodified lower path as shown in fig.( 2-e,f). 5. the specific examination for finding optimal path the following examination is done on all the resulted paths from (oac) in order to find the optimal path which is accomplished by checking all the resulted paths with respect to: § length of each path: the length of the path is considered an important factor in determining the best path because the robot will consume less time to reach the goal point when the path is shorter. § number of segments: the number of segments of the resulted path is associated with number of turns that the robot must do to access the desired path. it is considered an important factor in finding the best path because the robot's motors will consume less power to reach the goal point when the path contains less number of segments, because it requires less number of turning to change its direction to follow the next segment direction. 5.1 clearance factor (c) it is worth mentioning that the size of the obstacles which are submitted to (oac) algorithm is larger than their actual size because a factor which is called clearance factor is added to their dimensions in order to prevent the robot from penetrating the obstacles or being in contact with them. the clearance ( c ) is: c =r + t + s where: r = radiuas of the plateform robot . t = thickness of the wheels of the robot. s = safety factor . 5.1.1 the effective role for factor (s) factor ( s ) is assumed by ( oac ) algorithm in order to ensure that the robot when it is turning around the obstacle to follow the specific planned path, it will never penetrate the obstacles or be in contact with their edges, so it must be added to the obstacle's dimensions. the value of this factor is free and is left for the programmer of the robot who decides this value with respect to the environment, robot dimensions, the obstacles' dimensions and their distribution within the environment which the robot must navigate within it. according to the properties of the environment, pioneer mobile robot and the obstacles which are used in this experimental work, the value of factor ( s ) ranging ( from 5 to 10 cm) and this is considered its normal value in most of other cases. the free selection of the factor ( s ) value gives it an importance which clearly appeared in some complex environments that contain large number of close obstacles. this type of environments is called crowded environments. in this environments the distances between the obstacles are enough for the robot to navigate between them according to the planned paths, but these paths are not practical, because they have large number of curves and large length as shown in figures ( 3 – a ,b). so, with clever selection of factor ( s ), we can conclude these distance and merge these obstacles with each other to form a single irregular obstacle which can be regulated ( by converting it into single rectangular obstacle ) and then this obstacle is submitted to ( oac ) algorithm to find the optimal path as shown in figure ( 3.c) . (a) modified upper path (b) modified lower path for small s for small s (c) optimal path for large s fig.3. crowded environment. nabeel k. abid alsahib al-khwarizmi engineering journal, vol. 7, no. 4, pp 1 -16 (2011) 5 6. obstacle regulation to make the (oac) algorithm capable of being applied for all obstacles, it is suggested that their shapes must be converted into regular shapes (it is a supposed term that refer to the specific shape which can be submitted to (oac) algorithm which is the rectangular shape only while all other shapes such as atriangle is considered irregular shape), so any other shape must be converted into a rectangular shape. we regulate the obstacle's shape by building a matlab subprogram which is part of (oac) algorithm. 7. mrl and mrs as explained previously, the (oac) algorithm gives us a number of paths. the modified upper and the modified lower path (the optimal path is one of them) are resulted from achieve modifications on the upper and lower paths respectively. this modification is done either in the lengths of these paths or on the number of the individual lines (segments) which form them. we suggest two formulas to find the value of these modifications for each case study: modification rate with respect to path length (mrl); (mrl) = %100* lengthpath largest length path smallest -lengthpath largest modification rate with respect to no. of segment (mrs); (mrs)= %100* segment of no.path largest segment of no.path smallest -segment of no.path largest 8. oac flow chart figure (4) shows the flowchart of both matlab and c++.net programs to implement oac algorithm with all the required details. start robot initialization read mobile robot start point ( x1, y1) input goal point (xg, yg) read environment's image received from wireless camera in color representation convert the coulured image to gray scale image and then to binary image ( 0,1) matrix remove noise from the resulted image using median filter detect all the obstacles in the environment examine all the obstacles' shapes m nabeel k. abid alsahib al-khwarizmi engineering journal, vol. 7, no. 4, pp 1 -16 (2011) 6 fig.4. the program flowchart. figure (4) continued 9. simulation and experimental work the work in this paper can be divided into two parts: • simulation: it enables us to see the original image, the processed image, the (oac) algorithm steps and all the resulted paths .this is accomplished by matlab program. • experimental work: this part include the programming of the robot with c++.net program by wireless connection in order to reach the goal point according to optimal path. m are the obstacles' shapes regular? adding a border = clearance (c) around all the obstacles regulate it no ye s select it as the modified upper and lower path n find the upper and lower path can be modified? find the intermediate upper path can be modified ? no yes yes no n select the optimal path with respect to time and power upload the resulted optimal path to c++ .net program by matlab/ c++.net interface c++ .net program send the robot to reach the goal point according to the optimal path by wireless connection is the robot reached the goal point? end no yes nabeel k. abid alsahib al-khwarizmi engineering journal, vol. 7, no. 4, pp 1 -16 (2011) 7 9.1. simulation using matlab in order to get a complete the image about the overall work, and be able to see all the results before the order is being sent to robot, the process can be simulated so that we can see the original environment's image, the noised image, the converting steps of this image, the filtered image, the oac algorithm steps and all the resulted paths and the optimal path. matlab program which is built in order to achieve image processing and the (oac) algorithm steps can also be used as a simulation tool to display all the above information to be clear for the programmer. this is considered important requirement to enable the programmer to see the results, to modify the program if required and to explore the error if it is found and determine in which stage of the process it happened. 9.2. experimental work the (oac) algorithm required the environment's image to be processed to and find the optimal path instantaneously. this required a camera as shown in figure (5) ready in any moment to offer the image of environment. for this purpose a wireless camera is used here to accomplish this task. after the image is sent to matlab program (by camera – computer wireless connection) and as soon as the approximately optimal path is found, the path information is processed by the built c++.net program in order to program move according to this path until it reach the goal point without collision with obstacles found on its way . this task represents the experimental side of this work. fig.5. wireless camera. in work, we use this camera by fixing it above any unknown environment, with a suitable height that offer the required image requirement and cover nearly all the area of the work which is nearly (2.4 m x 3.2 m) square area. the wireless camera is suited above the environment by using aluminum bar with length of (4 meter) as shown in figure (6) and the group is fixed on height of (5 meter). fig.6. modeling camera – aluminum bar connection. 9.3. model environment the environment is chosen to be a rectangular area with dimensions (2.4 m x 3.2 m) depending on the wireless camera specification .the group of environment, wireless camera, pioneer mobile robot and obstacles can be modeled as in figure (7). fig.7. model environment. nabeel k. abid alsahib al-khwarizmi engineering journal, vol. 7, no. 4, pp 1 -16 (2011) 8 10. path planning cases studies a number of experiments were carried out (see table 1) as shown in figures (8-16), to test the ability of the mobile robot to reach its goal with approximately optimal path found according to (oac) algorithm. these experiments, represented by the cases studies explained in the next section, are done depending on the built matlab program to find the optimal paths and then these results are transferred by matlab – c++.net interface to the c++.net program in order to program the pioneer mobile robot to take this path through its navigation from the start point to reach the goal point. table 1, different cases studies fig.8. case study 1 fig.9. case study 2 fig.10. case study 3 fig.11. case study 4 fig.12. case study 5 fig.13. case study 6 fig.14. case study 7 fig.15. case study 8 fig.16. case study 9 description case study index an environment with single obstacle case study 1 1 an environment with two obstacles case study 2 2 an environment with two irregular obstacles case study 3 3 an environment with three obstacles case study 4 4 an environment with three obstacles / for different start and goal points case study 5 5 an environment with three obstacles including irregular shapes case study 6 6 an environment with four obstacles case study 7 7 an environment with six obstacles case study 8 8 an environment with crowded obstacles case study 9 9 nabeel k. abid alsahib al-khwarizmi engineering journal, vol. 7, no. 4, pp 1 -16 (2011) 9 one of these case studies (case study 6) will be explained in details as follow: 11. an environment with three obstacles including irregular shapes the environment which is shown in figure (17) of dimensions (2.4m x 3.2m) contains three obstacles one of them is regular (rectangular 20 cm x 30 cm in area) and the others are irregular (triangle shape is considered irregular according to oac algorithm principles of 20 cm height and 30 cm base), the start and goal point are (437, 53) and (159, 465) respectively. this image is sent by wireless connection to the matlab program to apply oac algorithm on it, so the results are as follows: • convert this colored image into a gray scale image as shown in figure (18). • convert this grayscale image into binary image (0, 1 representation) by selecting suitable threshold as shown in figure (19), note that the image is noised with pepper noise. • remov noise from the image and regulate the obstacle's shape. since the image is highly contemplating with noise it is required to be applied to the filter twice in order to remove the noise completely as shown in figure (20). • add a border of thickness = c = 67 pixels (as previously explained in chapter 3) to ensure that the robot will not be in contact with any obstacle through its navigation according to the specified path as shown in figure (21). • detect the obstacle edges by building programming steps to find it as shown in figure (22). • find the upper path, note that the path is at a distance = c (represented by red color) from the obstacle in order to prevent the robot to touch obstacle and to enable it to move according to its path freely. from this path the intermediate and modified upper path are found as shown in figure (23). • find the upper path, note that the path is at a distance = c (represented by red color) from the obstacle in order to prevent the robot from touching the obstacle and to enable it to move according to its path freely. from this path the intermediate and modified upper path are found as shown in figure (23). fig.17. the environment fig.18. the gray scale image image fig.19.binary image fig.20.the filtered and regulated image fig.21. the resulted fig.22. detect the image after adding edges of obstacle a border = c fig.23. the all resulted paths according to oac algorithm. nabeel k. abid alsahib al-khwarizmi engineering journal, vol. 7, no. 4, pp 1 -16 (2011) 10 as shown, five paths resulted in this case study and according to the criteria of determining the optimal path with respect to (oac) algorithm the optimal path is the modified lower path because it is the smallest one in length and in number of segments, see table (1). the above results represent the matlab simulation of this case. when the optimal path is sent for pioneer mobile robot, it successfully reaches the goal point without collision with any obstacle in the area as shown in figure (24). fig.24. the robot navigation according to the optimal path 12. results and discussion the results were for different cases by taking different images and comparing between the behavior of path and navigation of the robot in unknown environment, changing obstacles number and positions and their effectiveness on the resulted paths (specially the optimal path), time required and power consumed for each path. the experimental work includes the following specifications: 1. the motion along the straight segments with constant speed (zero acceleration). this constant speed is 0.375 m / sec. 2. the motion at turning parts of the path with constant acceleration which is 0.1875 m / sec 2 . 3. radius of drive wheels r = 8.25 cm = 0.0825 m. 4. robot width b = 425 mm = 0.425m. 5. robot mass m = 9 kg. 6. no-load speed v max = 24.7 m/sec. 7. the connection type is a wireless ethernet-toserial * is connected directly to robot’s microcontroller; it works by automatically translating network-based ethernet packet communications tcp/ip into streaming serial for the robot microcontroller and back again. 8. battery = 12 volt. according to (oac) algorithm the table of results for all cases studies is shown in table (2) and the optimal paths for all cases studies are shown in table (3). table 2, resulted for all cases studies in details case study no. of paths resulted path total length cm time sec no. of segment k.e joul case study 1 1 upper path 244 9.5 4 0.563k 2 modified upper path 240* 7.5 2 * 0.1875 k 3 lower path 423 16.28 6 0.938 k 4 intermediate lower path 320 11.53 4 0.563 k 5 modified lower path 308 10.2 3 0.375 k case study 2 1 upper path 304 14.11 7 1.125 k 2 modified upper path 276 * 9.36 3 * 0.375 k 3 lower path 628 26.75 11 1.875 k 4 intermediate lower path 412 16 6 0.938 k 5 modified lower path 356 12.5 4 0.563 k nabeel k. abid alsahib al-khwarizmi engineering journal, vol. 7, no. 4, pp 1 -16 (2011) 11 case study 3 1 straight line path 252 6.72 1 zero k case study 4 / a 1 upper path 252 10.72 5 0.75 k 2 modified upper path 200 7.33 3* 0.375 k 3 lower path 220 9.86 5 0.75 k 4 modified lower path 184* 7 3* 0.375 k case study 4 / b 1 upper path 384 18.24 9 1.5 k 2 intermediate upper path 304 14.1 7 1.125 k 3 modified upper path 278 10.25 4 0.563 k 4 lower path 764 28.4 9 1.5 k 5 1'st intermediate lower path 304 12.1 5 0.75 k 6 2'nd intermediate lower path 280 10.46 4 0.563 k 7 modified lower path 276* 9.36 3* 0.375 k case study5 /a 1 upper path 212 9.65 5 0.75 k 2 modified upper path 180 * 6.8 3* 0.375 k 3 lower path 220 9.87 5 0.75 k 4 modified lower path 188 7 3* 0.375 k case study5 /b 1 upper path 192 9.12 5 0.75 k 2 modified upper path 160 * 6.27 3* 0.375 k 3 lower path 192 9.12 5 0.75 k 4 modified lower path 160 * 6.27 3* 0.375 k case study5 /c 1 upper path 284 11.57 5 0.75 k 2 modified upper path 236 8.3 3 0.375 k 3 lower path 260 11 5 0.75 k 4 intermediate lower path 224 9 3 0.375 k 5 modified lower path 200 * 6.34 2 * 0.1875 k case study5 /d 1 lower path 384 17.24 8 1.3125 k 2 modified lower path 328 * 11.75 4 * 0.563 k 3 upper path 512 22.65 10 1.688 k 4 intermediate upper path 424 16.31 6 0.938 k 5 modified upper path 356 12.5 4 * 0.563 k case study6 / a 1 upper path 396 15.56 6 0.938 k 2 intermediate upper path 312 11.32 4 0.563 k 3 modified upper path 300 9 2 * 0.1875 k 4 lower path 280 10.47 4 0.563 k 5 modified lower path 260 * 8 2 * 0.1875 k case study6 /b 1 upper path 592 23.79 9 1.5 k 2 intermediate upper path 420 15.2 5 0.75 k 3 modified upper path 396 * 12.56 3 * 0.375 k 4 lower path 604 24.11 9 1.5 k 5 modified lower path 528 20.1 7 1.125 k nabeel k. abid alsahib al-khwarizmi engineering journal, vol. 7, no. 4, pp 1 -16 (2011) 12 note : the star sign refers to the optimal selection. table 3. optimal path information for all cases studies. case study7 1 upper path 376 17 8 1.3125 k 2 modified upper path 308 * 11.2 4 0.563 k 3 lower path 429 20.44 10 1.688 k 4 intermediate lower path 376 13.03 4 0.563 k 5 modified lower path 340 11.07 3 * 0.375 k case study8 1 upper path 384 14.24 5 0.75 k 2 modified upper path 296 * 9.9 3 * 0.375 k 3 lower path 456 16.16 5 0.75 k 4 modified lower path 356 11.5 3 * 0.375 k case study9 / small s 1 upper path 742 39.8 21 3.75 k 2 intermediate upper path 404 20.77 11 1.875 k 3 modified upper path 435 * 14.66 5 * 0.75 k 4 lower path 720 39.2 21 3.75 k 5 intermediate lower path 476 22.7 11 1.875 k 6 modified lower path 465 20.4 9 1.5 k case study 9 / large s 1 upper path 436 15.63 5 0.75 k 2 intermediate upper path 429 13.44 3 0.375 k 3 modified upper path 425 * 12.33 2 * 0.1875 k 4 lower path 515 17.73 5 0.75 k 5 modified lower path 483 14.88 3 0375 k case study optimal path total length (cm) time (sec) no. of segment k.e joul mlr % mls % msc ts case study 1 modified upper path 240 7.5 2 0.1875 k 43 67 1 5 case study 2 modified upper path 276 9.36 3 0.375 k 56 73 1 5 case study 3 straight line path 252 6.72 1 zero 0 0 0 1 case study 4/a modified lower path 184 7 3 0.375 k 27 40 1 4 case study 4/b modified upper path 272 10.25 4 0.5625k 65 67 2 7 case study 5/a modified upper path 180 6.8 3 0.375 k 18 40 1 4 case study 5/b modified upper & lower path 160 6.26 3 0.375 k 17 40 1 4 case study 5/c modified lower path 200 6.34 2 0.1875 k 30 60 2 5 nabeel k. abid alsahib al-khwarizmi engineering journal, vol. 7, no. 4, pp 1 -16 (2011) 13 where and constant depend on the dc motor parameters (k). 12.1. modification step cycle (msc) it is the processing time (during programming) which is required for modifying the path from one form to another according to (oac) algorithm (for example converting the lower into an intermediate lower path or into a modified lower path directly). 12.2. selecting time (ts) it is the processing time (during the programming) which is required for selecting the optimal path among all the resulted paths according to (oac) algorithm. 13. length and number of segments of resulted paths in all previous case studies, the resulted paths is different from each to other as a result of optimal path criteria which try to modify the upper and lower paths to get the optimal path either with respect to length or number of segments ( as explained in previous chapters). the modification level is different from one case to other depending on number of obstacles, position and distribution of them with respect to start and goal point's positions, size of obstacles …, etc. however the value of this level in all experiments is that the resulted paths are modified with respect to their length and number of segments. figure (25) show how in case study 5, the length and number of segments of resulted paths are decreased with increasing the index of paths. (a) path length with (b) path no. of respect to path index segments with respect to lower path index (c) path no. of segments with respect to path upper index. fig. 25. path length and no. of segments variation for case study 6 . case study 5/d modified upper path 328 11.75 4 0.5625k 36 60 1 5 case study 6/a modified lower path 260 8 2 0.1875 k 35 67 1 5 case study 6/b modified upper path 396 12.56 3 0.375 k 35 67 2 5 case study 7 modified upper path 308 11.2 4 0.5625k 28 40 2 5 case study 8 modified upper path 296 9.9 3 0.375 k 35 70 1 4 case study 9/ small s modified upper path 400 14.66 5 0.75 k 46 76 2 6 case study 9 / large s modified upper path 425 12.33 2 0.1875 k 18 60 2 4 nabeel k. abid alsahib al-khwarizmi engineering journal, vol. 7, no. 4, pp 1 -16 (2011) 14 14. conclusion a proposed path planning algorithm which is called (oac) algorithm is proposed in this work and it is applied to pioneer p3-dx mobile robot to obtain the optimal path ( in time and power ) in 2d static environment. the building algorithm is based on the observation , analysis of the obstacles that intersects with the supposed straight path that connects the start and goal point and conclude the resulted paths and select the better one among them according to lengths and the number of the individual lines which form them. it is worthy to mention that this algorithm can be applied for dynamic environments by progranning the cammera to provide an instantaneous image for the environment for each spesific time and make the program repeat itself consequently in intervals. this algorithm requires less computations power than most of other algorithms, because the selection of the optimal power is applied maximally among six or seven paths. the optimal path selection is not submitted to known optimization criteria , but it is found by a teqnique that give us the better path which is not only the shortest one but also the less one in consuming power. this with addition to advantages of the (oac) algorithm gives it enough strength that qualifies it to compete with all other path planning algorithm and excel on some of them. the advantages of ( oac) algorithm are : • the possibility of changing the start and goal points for any values and from any direction. this is considered a constraint for some path planning algorithms which do not have this ability. • this algorithm can be applied for different shapes of obstacles by creating new suggestion which said that " all different shapes of obstacles can be regulated by converting them into square or rectangular shapes only ". this is considered a treatment for some path planning algorithms which is constrainted by the shape of the obstacles. • the resulted optimal path is the shortest one in length as compared with the other paths which resulted acccording to oac algorithm (and so in time that the robot required to accomplish this path ) when it compared with some path planning algorithms such as genetic algorithms and the potential field algorithms [3] as shown in figure (26-a). • the resulted optimal path consummes less the power and it is required to change its direction in the curved parts in the resulted path ( because it is smooth and contains small number of curves ) as compared with potential algorithm as shown in figure (26-a ). this resulted path is considered more economic as shown in figure (26-b). fig.26. comparison between oac path and potential field path 15. references [1] steven m. cavalle, 'planning algorithm', cambridge university press 2006. [2] pioneer reference book, www.mobilerobotics.com. 2008. [3] adam hoover, bent david olsen,' path planning for mobile robots using a video camera network ', in proc. of ieee/asme int'l conf. on advanced intelligent mechatronics, 1999. [4] 'computer vision and image processing ', scott e. umbaugh, prentice hall press 1998. [5] kamran h. sedighi, kaveh ashenayi, theodore w. manikas, roger l. wainwright, heng-ming tai. , 'autonomous local pathplanning for a mobile robot using a genetic algorithm', vol.2, 2004, page(s): 1338 1345, ieee. [6] anand veeraswamy, 'optimal path planning using an imported a* algorithm for homeland security applications ', february 2006, aia'06: proceedings of the 24th lasted international conference on artificial intelligence and applications. [7] andrew n. hand, jagruthi godugu, kaveh ashenyi, theodore w. manikas, roger l. wainwrightb. 'benchmarking robot path planning ', annie 2005. [8] mehmet serdar guzel, 'mobile robot navigation using a vision based approach', 2003. (a) the resulted path according to potential field algorithm [3] (b) the resulted path according to (oac) algorithm http://www.mobilerobotics.com nabeel k. abid alsahib al-khwarizmi engineering journal, vol. 7, no. 4, pp 1 -16 (2011) 15 [9] 'digital image processing' /second edition / rafael c.gonzalez / 1987. [10] amar rezoug, mohand said djouadi , 'visual based lane following for nonholonomic mobile robot' , vol. iii (2008), suppl. issue: proceedings of icccc 2008, pp. 475-479 , int. j. of computers, communications & control, issn 18419836, e-issn 1841-9844 . [11] arvind antonio de menezes pereira, 'navigation and guidance of an autonomous surface' , volume 60, issue 2, march 2008 , on pages 133-143, computers and electronics in agriculture. [12] ethar h.khalil, 'application of probability recursive method for path planning ', msc. thesis, 2008. [13] 'visual c++.net', michel hyman, hungry minds, 2002. [14] 'problem solving with c++'/ walter savitch, addison wesley / 1999. [15] 'visual c++.net', h.m.deitel , 2004 ,prentice hall press. )2011( 1 16 ، صفحة4، العدد7مجلة الخوارزمي الھندسیة المجلد نبیل كاظم عبدالصاحب 16 لي متحركآنسان السیطرة على المسار المخطط أل آمنة عبد الھادي صالح بدالصاحب نبیل كاظم ع جامعة بغداد/ كلیة ھندسة الخوارزمي/ المیكاترونیكس ھندسة قسم dr-nabeelalsahib@hotmal.com :االلكتروني البرید الخالصة ال ذاتي الق ائم عل ى تقنی ات معالج ة ذو ال تحكم p3-dx pioneerن وع للروب وت المتح رك تخطیط المس ار المتوق ع یقدم ھذا البحث خوارزمیة جدیدة ل الص ورة للحص ول عل ى المس ار یتم تطبیق الخوارزمیة المقترح ة عل ى ھ ذه . الصور باستخدام الكامیرا الالسلكیة التي توفر الصورة المطلوبة لبیئة مجھولة في الطریق المستقیم بین نقطة البدایة والھدف من خالل الكشف عن ھذه العقبات ، تقع وھو یقوم على رصد وتحلیل العقبات التي. للروبوت و االفضل األمثل .الذي یربط بین نقطة البدایة والھدفالمسار االفضل لى لعثور عا ، ومحاولة المفترض المستقیم ونقاط التقاطع مع الطریق مواقعھاوتحلیل ودراسة أشكالھا و .) اتصال السلكي للروبوت المتحرك -الكمبیوتر -كامیرا السلكیة (: یتضمن تمثیل النظام العام ان وذلك األمثل تقریباالذي یطبق على صورة بیئة إلیجاد الطریق )matlab(بلغة برنامج ویشمل بناءالجزء االول , ئین اساسیینھذا العمل تضمن جز visual(ال ى البرن امج ال ذي ت م بن اؤه بلغ ة مس ار المعلوم ات تزوی د وی تم c++.net) matlab ( م ن خ الل التعش یق ب ین اللغت ین الب رمجیتین c++.net (الروبوت الخاصة ببرمجة)pioneer p3 dx (لتحقیق المسار المطلوب. یرسل لھا إلى جھاز الكمبیوتر الذي یعالج ، في دوره ، ھذه الصورة وثم یرس الواقعیة أخذ صورة للبیئةتسلكیة استخدام كامیرا الالثاني یتمثل بالجزءاما .وفقا لھذا المسار لكي یسیر) visual c++.net برمجتھ بلغة تم مسار إلى الروبوت الذيالمعلومات ) السلكيالتصال اال عن طریق( و ال ذي ت م الوصول إلى الھدف عبر المسار األمث ل و بدایة البنجاح من نقطة تمكن من الحركة ) pioneer p3 dx(أن الروبوت النتائج العملیة بینت حیث تم ایجاد مسارین ھما المسار العلوي والمسار السفلي ثم وفقا لھذه الخوارزمیة ت م تح دیثھما , التي تم بناؤھا ھنا من الخوارزمیةیھ كنتیجة الحصول عل وم ن خ الل فح ص , لینتج منھما المسار العلوي الوسیط و المسار السفلي الوسیط ومن ثم الحصول على المسار العلوي المحسن و المس ار الس فلي المحس ن .ن النھائیین نسبة للوقت و الطاقة یتم اختیار المسار االمثل للروبوتھذین المساری mailto:dr-nabeelalsahib@hotmal.com سناء نعمان58-48 al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 7, no. 3, pp 48 58 (2011) analysis of temperature and residual stress distribution in co2 laser welded aluminum 6061 plates using fem sanaa numan mohammed department of manufacturing operations/ al-khwarizmi college of engineering/ university of baghdad (received 22 february 2011; accepted 19 jun 2011) abstract this paper develops a nonlinear transient three-dimensional heat transfer finite element model and a rate independent three-dimensional deformation model, developed for the co2 laser welding simulations in al-6061-t6 alloy. simulations are performed using an indirect coupled thermal-structural method for the process of welding. temperature-dependent thermal properties of al-6061-t6, effect of latent heat of fusion, and the convective and radiative boundary conditions are included in the model. the heat input to the model is assumed to be a gaussian heat source. the finite element code ansys12, along with a few fortran subroutines, are employed to obtain the numerical results. the benefit of the proposed methodology is that it offers the capability of optimizing laser welding process, and also provides a reliable estimation of the developed temperatures, as well as the thermal stress (residual stress) and strain fields reducing the experimental effort. keywords: laser welding; aluminum alloys finite element analysis. 1. introduction a successful lightweight construction is the result of an optimized combination of material selection, design and manufacturing. when the lightweight components are made from aluminum alloys, welding is one of the most widespread joining technologies available. in order to avoid costly trial-and error experiments and to improve the in-service quality of assemblies, numerical simulation of welding can be a powerful tool. laser welding could be used in place of many different standard processes, such as resistance (spot or seam), submerged arc, rf induction, high-frequency resistance, ultrasonic and electronbeam. while each of these techniques has established an independent niche in the manufacturing world, the versatile laser welding approach will operate efficiently and economically in many different applications. its versatility will even permit the welding system to be used for other machining functions, such as cutting, drilling, scribing, sealing and serializing. laser beam welding has been identified as a promising method for joining aluminum in body applications such as tailored blanks. due to rapid heating and cooling, welding process produces inevitably large residual stresses in the engineering structures, which often approach the yield strength of the material. for the key components such as the welded joints in nuclear power plants, design and structural integrity assessments require an account of residual stresses. therefore, measuring and predicting welding residual stresses are very important. many of the advantages and limitations of laser welding, compared to other welding processes, depend on focused beam properties. the high power density permits welding based on the keyhole principle, and the reduced energy transfer to the material produces a very narrow heat affected zone (haz) with low residual stress and small distortions [1]. the aim of the present work is the employment of finite element (fe) method to assess thermal and mechanical fields in terms of temperature, stress and strain distributions in laser welded joints made of al-6061-t6 alloy. the understanding of the heat-process of welding is important for the analysis of welding structure sanaa numan mohammed al-khwarizmi engineering journal, vol. 7, no. 3, pp 48 58 (2011) 49 mechanical and microstructure and controlling of welding quality [2]. therefore, numerical simulation of the welding process has been a major topic in welding research for several years. the results of simulations can be used to explain the physical essence of some complex phenomena in welding process explicitly and also can be used as the basis for optimizing the welding parameters. a number of analytical and numerical models of welding processes have been used to evaluate temperature and stress distribution during and after the welding process, and predict the residual stresses and final distortions of structural components. these include analytical models [36], two dimensional finite element models [7, 8] and three dimensional finite element models of laser [9-12]. in the present investigation, a three dimensional finite element model for the laser welding simulation was developed. it considers a gaussian distribution of heat flux using a moving heat source. a nonlinear thermo-mechanical analysis was performed using temperature dependent material properties. 2. finite element analysis in laser welding process the focal spot is targeted on the workpiece surface which will be welded. at the surface the large concentration of light energy is converted into thermal energy. the surface of the workpiece starts melting and progresses through it by surface conductance. for welding, a very narrow zone under the laser beam is suddenly heated, vaporized and locally fused. after welding and cooling the melted material, the assembly of the welded pieces is achieved. on the exposed area a keyhole is shaped. the elevated temperature gradients present in this area during both the heated and the cooling along with the sharp decrease of mechanical properties during heating, yield to nonhomogeneous permanent strains and residual stresses after the process. a three dimensional transient, isotopic solid with moving heat source finite element model was developed to simulate the laser welding process using the commercial code ansys12. the finite element model is shown in fig. 1. the whole length of the plate is 200mm, the width is 100mm and the thickness is 4 mm. for the solution, a thermo-elasto-plastic analysis was performed using the enhanced finite element with user fortran subroutine. the solution was generated in two basic steps. first a transient heat transfer analysis was performed and the resulting temperature field was used on the second step as an input to the mechanical analysis. an appropriate time-stepping scheme was used for each analysis to achieve fast convergence of the solution and reasonable accuracy. fig.1. three-dimensional finite element model. temperatures induced in the plate by irradiation can be calculated by the nonlinear transient thermal finite element equation (eq. 1). as can be seen in the equation, the temperaturedependent material properties of the plate have to be involved for the nonlinear problem, and the time-dependent heat loads are required for the transient problem. …(1) where x, y, z are the cartesian coordinate, (the internal heat generation), ρ (the density), k (the thermal conductivity) and cp (the specific heat) are the functions of temperature t. three types of solid elements are commonly used for a three-dimensional model – brick, wedge, and tetrahedron. it is a primary condition to use the appropriate elements for finite element models to obtain the most accurate solution through the finite element analysis. in the present thermal analysis, the sheet metal is meshed using a brick element (called solid70) because the element is more accurate and more computationally efficient than a comparable tetrahedron one. figure 2a shows the geometry, node locations, and the coordinate system of solid70, which has eight nodes with a single degree of freedom, temperature, at each node. sanaa numan mohammed al-khwarizmi engineering journal, vol. 7, no. 3, pp 48 58 (2011) 50 heat fluxes and convections can be an input as surface loads at the element faces as shown by the circled numbers on the element geometry. the surface loads are defined with the nodes or elements. an advantage of the use of the element is that this element can be replaced by an equivalent structural element for structural analysis. for the consideration of the radiation effect on the plate surface, a three dimensional thermal surface effect element (surf152) is used overlaying it onto the faces of the base elements made by solid70. figure 2b shows the geometry, node locations, and the coordinate system of the element, which is defined by four to nine nodes and the material properties (e.g., emissivity). an extra node has to be generated to reflect the radiation effect, which is positioned away from the base element. for mechanical analysis, a structural element defined by eight nodes (i.e., solid45) is used for three dimensional modeling of the plate. each node of the element has three degrees of freedom: translations in the nodal x, y, and z directions. the element supports analysis of plasticity, large deflection, large strain, stress stiffening, creep and swelling. for the structural analysis, the heat transfer model containing the equivalent thermal element solid70 can be replaced by this element, and temperatures obtained from the thermal step can be applied as element body loads at the nodes. the geometry, node locations, and the coordinate system of this element are equal to the solid70 (see figure 2 a). figure (1) shows the meshes generated for the present simulation. the meshes are composed of a total number of 80,000 solid elements and 20,000 surface elements. fig.2. geometries of: (a) the three-dimensional thermal solid element, solid70; and (b) the thermal surface effect element, surf152. 3. material properties as can be seen in eq.(1), temperature response in a material involved in high heat fluxes is determined by the thermal material properties of thermal conductivity, specific heat, and density, which are dependent on temperatures. the accurate calculation of temperatures is critical in laser welding because bending variables of stress and strain are dependent on temperatures. therefore, temperature dependent thermal properties of al-6061-t6 plate are used in the finite element model. the thermal material properties of al 6061-t6 are presented in fig. 3, after ref. [13], while temperature dependent material mechanical properties young’s modulus, sanaa numan mohammed al-khwarizmi engineering journal, vol. 7, no. 3, pp 48 58 (2011) 51 poisson’s ration, density and thermal expansion coefficient are presented in fig. 4. fig.3 thermal properties for al alloy 6061-t6 (after ref. [13]). fig.4. mechanical properties for al alloy 6061-t6. 4. thermal analysis 4.1. heat flux input the heat intensity on the plate surface by laser beam is modeled as an idealized gaussian distribution, and the heat flux is described as follows: ...(2) where: =the intensity of the incident heat flux at the material surface η =heat transfer efficiency p = beam power r =beam diameter r = distance from the center of the laser beam the mean thermal flux density (r), within the area of the laser beam is calculated from eq. (2) as follows [14]: …(3) in the present simulation, the heat flux, (r) obtained from eq. (3) is used as a surface load, and the load is imposed on the selected set of element faces of the plate surface. the movement of the laser beam is realized by adopting the local coordinate system to apply heat loads as a step. as shown in figure (5), the local coordinates are generated along the heating line as defined steps first; then at each step, the center of the laser beam is located at the origin of the local coordinate and the heat load is applied on the elements placed inside the laser beam (illustrated line circle). in order to ensure convergence, the heat loads are imposed by small increments using *do loop command. fig.5. local coordinates and laser beams related to the coordinates. the heating time, ts, at each step is described as follows: …(4) where: lp = length of plate, vs = speed of laser beam, ne = number of elements along the heating line. the numerical values for heat source parameters used in this paper are shown in table1. sanaa numan mohammed al-khwarizmi engineering journal, vol. 7, no. 3, pp 48 58 (2011) 52 table 1, simulation conditions of the laser welding process. laser power (w) scanning speed (mm/s) beam diameter (mm) number of irradiation 1500 10 12 1 4.2. boundary conditions three boundary conditions associated with equation (1) are shown in figure (6). fig.6. thermal boundary conditions. the boundary conditions used include: • adiabatic condition is considered on the laser path due to symmetry. • heat losses from the plate surfaces to the surroundings take place by means of natural convection and radiation effects. for the radiant heat loss, qr, …(4) where: σ = the stefan-boltzmann constant (σ=5.67*10-8 w/m2.ko) εr = the emissivity of radiating surface (εr=0.5) tr = the absolute temperature of radiating surface t∞ = the absolute temperature of surrounding (t∞=298 ko) for the convective heat loss, qc, …(5) where: hf = the convection coefficient (h=30 w/m2.ko) ts = the temperature at the plate surfaces 5. mechanical analysis a non-linear mechanical analysis is executed just after each thermal analysis step, in order to calculate stress and strain distributions of the structure. the results of the thermal analysis step (transient temperature distribution) serve as loading to the corresponding mechanical analysis step. the introduced temperature dependent material mechanical properties young’s modulus, poisson’s ration, density and thermal expansion coefficient are presented in fig. 4. in the mechanical simulation, the elastic behavior is modeled using the isotropic hooke’s rule with temperature-dependent young’s modulus. the thermal strain is considered using thermal expansion coefficient. for the plastic behavior, a rate-independent plastic model is employed. the yield criterion is the von mises yield surface. in the present numerical model, the strain hardening is taken into account using the isotropic hardening law. the non-linear mechanical analysis problem is described by the following general fe equation: [k(t)]{u(t)} + {f(t)} + {fth(t)} = 0 …(6) where k(t) is the temperature-dependent stiffness matrix; f(t) the external load vector; fth(t) the temperature load vector; {u(t)} is the displacement vector. the newton–raphson algorithm is utilized for solving the non-linear equation system and the newmark integration scheme is applied for the numerical integration in the time domain. the mechanical boundary conditions are constrained only for preventing rigid body motion with considering symmetry. the simulations are conducted on a personal computer with a 2.1ghz cpu and a 4.0gb memory. the total computational time used is 28 h or so. 6. simulation results 6.1. temperature and residual stresses field induced by laser beam welding using the geometry, the mesh and the heat flux distribution model described above and the geometrical parameters of the welded pool, the thermal analysis was first conducted. figures 7(a)(d) show the temperature distribution on the welding parts at four different times during the process. the figures show clearly the large temperature gradients at the area close to the laser beam and also indicate the cooling of the workpieces away from the heat source. figure 7a shows temperature distribution on the surface of sanaa numan mohammed al-khwarizmi engineering journal, vol. 7, no. 3, pp 48 58 (2011) 53 the welded plate at time t= 35 sec (i.e. at the beginning of the welding process). figure 7b shows temperature distribution on the surface of the welded plate at time t= 100 sec (i.e. when the laser beam is passing the center of the plate) while figure 7c indicate the temperature distribution at the last step of heating process. figure 7d shows the situation (temperature distribution) after cooling. figure 8 is captured from the left side view on the x-z plane crossing the centre of the plate. it is noted that the maximum temperature occurs in the rear of the centre of the beam during heating, and the temperature gradient is steeper in the front of the centre of the beam than that in the rear. the keyhole shape from the fe analysis is shown in figure 8, this shape gives good approximate shape for the weld pool measured by many experimental studies. figure 9a shows the temperature history at a node in the welding zone of the plate. the temperature rises rapidly and reaches a maximum of nearly 861 °k and then subsequently drops smoothly at the same rate when the laser beam moves away from the welding point, indicating that the steep temperature gradient collapses rapidly. figure 9b shows the temperature distribution across a perpendicular path to the welding line; the figure indicates that the temperature is maximum in the center of the welding zone and decreases gradually at the ends. to evaluate the residual stress distribution, the heat transfer analysis was performed first in order to find nodal temperatures as a function of time, and then in the second part of the analysis, a nonlinear mechanical analysis was carried using the temperature distributions which were obtained from the heat transfer model. temperature fields affect mechanical fields through thermal expansion and temperature dependent material properties. thermal expansion or contraction due to transient application of temperature gradients is usually the dominant concern in thermal stress analysis. the non-linear mechanical properties were used as shown in figure (4) and the yield criterion used is the von mises yield surface. the mechanical boundary conditions are constrained so that the two edges of the plate parallel to welding line are fixed to prevent rigid body motion. fig.7. temperature distributions at: (a) 35 sec; (b)100 sec; (c) 193 sec; and(d) 203 sec. -a-b -c-d sanaa numan mohammed al-khwarizmi engineering journal, vol. 7, no. 3, pp 48 58 (2011) 54 fig.8. keyhole shape and temperature distributions through the thickness direction at 117 sec. fig.9. (a) temperature history for a node in the weld zone. (b) temperature distribution across a path perpendicular to the welding line. longitudinal and transverse stresses at different times are shown in figures (10&11); the positive stress values representing the red region indicate the tensile stresses, and the negative stress values representing the blue region indicate the compressive stresses. figure (10) shows the stress distributions on the plate surfaces at four different stages of the process – when the heating is at the early stage (t = 35 sec) (a), when the laser beam is passing the center of the plate (t =100 sec) (b), when the operation is finished (t = 193 sec) (c) and , when the plate is cooled (t = 519 sec) (d). it is noticed from figure (10) (a) that when the heating begins, high compressive stresses of a maximum of 131 mpa arise in the heated surface and its neighboring zone due to thermal expansion by high temperatures. tensile stresses are produced in the region in front of the laser beam to counteract the thermal expansion constraining material in the surrounding. during the cool down phase of the heated zone, as shown in figure (10), the compressive stresses change to tensile stresses (a maximum of 121 mpa) due to the contraction of the heated zone. after the operation, the tensile stresses remain at the surface along the centerline of the plate. the shape of the residual stress (longitudinal) is shown in figure (12a). the figure indicates that after cooling the stresses are tensile in the center of the plate while they are compressive in the edges; the reason for this behavior can be found in the fact that recrystallization reduces the extent of residual stresses, that is higher at the interface between the mechanical stressed zone and the heat -a-b sanaa numan mohammed al-khwarizmi engineering journal, vol. 7, no. 3, pp 48 58 (2011) 55 affected zone. figure (12b) shows normal stresses orthogonal to the direction of the weld known as transverse residual stresses. fig.10. stress distribution in x-direction at different times a-35 sec, b-100 sec, c-193 sec and d-519 sec. fig.11. stress distribution in y-direction at different times a-35 sec, b-100 sec, c-193 sec and d-519 sec. -a-b -c-d -a-b -c-d sanaa numan mohammed al-khwarizmi engineering journal, vol. 7, no. 3, pp 48 58 (2011) 56 fig.12. residual stresses a) longitudinal stress, b) transverse stress. 7. conclusion a three dimensional finite element model has been developed to simulate the laser welding process and investigate the final distribution of both temperature and residual stresses fields of a butt joint aluminum 6061-t6 specimen. the finite element calculations were carried out using ansys12 finite element code, which take into account thermal, metallurgical and mechanical behavior. the successful modeling of the welding process largely depends on an accurate knowledge of the material properties, as well as a careful modeling of heat source and a realistic representation of the clamping conditions during welding. the results show that prediction of temperature and residual stresses can be achieved with good precision. also a main conclusion of this study is that the transient temperature distribution is highly affected by thermal conductivity and the residual stresses (longitudinal and transverse) are changed from tensile at the welding zone to compression at the edges due to thermal conductivity change. 8. references [1] petretis br, balciuniene m. peculiarities of laser welding of metals. lithuaniam j phys 2005,45(1),pp.59–69. [2] a.p. mackwood, r.c. craferb, thermal modeling of laser welding and related processes: literature review, opt. laser technol. 37 (2005) pp.99–115. [3] n. okerblow. the calculation of deformation of welded metal structures. her majesty’s office, london, uk,1958. [4] k. masubuchi. analysis of welded structures. pergamon press, oxford, uk,1980. [5] l.j.yang, z.m.xiao. elastic-plastic modeling of the residual stress caused by welding. j. material processing technology, 48(1995) ,pp. 589-601. [6] y.tanigawa,t. akai, r. kawamura, n. oka. transient heat conduction and thermal stress problems of a nonhomogeneous plate with temperature dependent material properties. j. thermal stresses, 19(1996),pp. 77-102 [7] a. chakravati, l.m. malik, j. goldak. prediction of distortion and residual stresses in panel welds, in: computer modeling of fabrication processes and constitutive behavior of metals. candadian government publishing center, ottawa, ont, 1986, pp.547-561. [8] s. fujii, n. takahashi, s. sakai, t. nakabayashi, m. muro. development of 2d simulation model for laser welding. proceeding of the spie, vol. 3888,2000. [9] m. r. frewin , d. a. scott. finite element model of pulsed laser welding. welding j., 1999, 15s-22s. [10] g. reinhart, b. lenz, f. rick, finite element simulation for the planning of laser welding application. proceeding of the 18th international congress on application of lasers and electro-optics(icaleo’99), san diego, ca,1999. [11] c. carmignani, r. mares, g. toselli. transient finite element analysis of deep penetration laser welding process in a single pass butt-welded thick steel plate, comput, meth. appl. mech. eng., 179, 1999, pp. 197-214. -a-b sanaa numan mohammed al-khwarizmi engineering journal, vol. 7, no. 3, pp 48 58 (2011) 57 [12] d. h. kang, k. j. son, y.s. yang. analysis of laser weldment distortion in the edfa ld pump packaging, finite element analysis des., vol 37, 2001, pp. 749-760. [13] soundararajan, v., zekovic, s., kovacevic, r.,thermo-mechanical model with adaptive boundary conditions for friction stir welding of al 6061. int. j. mach. tools manuf. 45,2005 1577–1587. [14] hu, z., etal. computer simulation and experimental investigation of sheet metal bending using laser beam scanning., international journal of machine tools and manufacture, 2001, 41(4), pp.589-607. )2011( 48 58، صفحة 3، العدد 7 مجلة الخوارزمي الھندسیة المجلد سناء نعمان محمد 58 6061تحلیل توزیع درجات الحرارة واالجھادات المتبقیة في صفائح االلمنیوم الملحومة بالیزر باستخدام طریقة العناصر المحددة دسناء نعمان محم جامعة بغداد/ كلیة الھندسة الخوارزمي/ عملیات التصنیعقسم ھندسة الخالصة لنمذجة عملیة االنتقال الحراري والتشوه المیكانیكي الحاصل في عملیة اللحام باللیزر في سبائك في ھذا البحث تم تطویر نموذج ثالثي االبعاد الخطي ولكون النموذج المقترح ھو الخطي فقد استخدمت . تم استخدام اسلوب المحاكاة الحراري والھیكلي المقترن الالمباشر في عملیة اللحام. t6-6061االلمنیوم باستخدام تم التحلیل . خواص حراریة ومیكانیكیة متغیرة مع درجة الحرارة مع االخذ بنظر االعتبار الظروف المحیطة بالعملیة مثل الحمل الحراري واالشعاع الفائدة المتوخاة من ھذا البحث ھو انھ یمكن اعتماد المنھجیة المقترحة في . fortranمع بعض البرامج الداعمة والتي كتبت بلغة ansys12برنامج .دراسة وتحلیل عملیة اللحام باللیزر وما یرافقھا من تشوھات واجھادات حراریة وبالتالي الحصول على عملیة لحام مثلى <4d6963726f736f667420576f7264202d20e5c7e4ed20e6dfc7d9e320e6d1d3e135322d3636> al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 14, no. 1, march, (2018) p.p. 52-66 study the effect of forming media on the hydroforming process for copper tube rusul abdulkareem salman* hani aziz ameen** kadhim mijbel mashloosh*** technical engineering college – baghdad/ iraq *email: rusulalizee@gmail.com **email: haniazizameen@yahoo.com ***email: kadm52@yahoo.com (received 29 march 2017; accepted 11 october 2017) https://doi.org/10.22153/kej.2018.10.003 abstract to observe the effect of media of the internal pressure on the equivalent stress distribution in the tube, an experimental study is done by constructing a testing rig to apply the hydraulic pressure and three dies are manufactured with different bulging configurations (square, cosine, and conical). in the other part, ansys apdl is generated to analyze the bulging process with hydraulic and rubber (natural and industrial) media. it was found that when the media is a rubber, the stress is decreased about 9.068% in case of cosine die and 5.4439% in case of conical die and 2.8544% in case of square die. so, it can be concluded that the internal pressure in the rubber media is much better than in hydraulic media. also, the force needed for forming the shape using rubber is higher than that of hydraulic and the force needed to form using industrial rubber is higher than of natural rubber. the thickness distribution in the tube wall in case of rubber media is better than that for hydraulic media and for the industrial rubber is better than that for natural rubber for the same dies. in case of hydraulic, the lower forming pressure is needed to bulging process compared with the rubber media since height stress in the tube metal is existed, which causes the failure. for the case of rubber, the forming pressure that was needed to bulge process is higher when compared with the hydraulic media but with less stress in tube metal and the failure in the wall is not existed with rubber media for the same pressure of hydraulic. keywords: ansys, bulging process, copper tube, hydroforming, industrial rubber, natural rubber, 1. introduction tube hydroforming is one of the cold forming operations on metal tubes, which takes it is a consideration all enough in the coming days. this process is carried out using a pressure (via hydraulic fluid or rubber media) in a closed tube from both sides. girard a.c. a et al., 2006[1], studied the bulging tube experimentally using rubber type of urethane rod. sadiq jaffar aziz, 2008[2], studied of tubes hydroforming process, by using of oil pressure developed inside the tube prepared to be formed also utilization axial force represented by axial displacement (axial end feed) that reduced the tube length, achieved an accept tube wall thickness distribution, and increased its thickness. selvakumar a. s., et al., 2012[3], studied the effect of deformation characteristics on tubular materials before and after heat treatment in hydroforming process. sami abbas hammood, 2012[4], studied the best path to form a tube in the square cross-sectional die relying on the hydraulic bulge test and numerical simulation to reduce loss of the cost and time in the experimental work that used copper and aluminum metals. emad jabour yousif, 2013[5], studied of the effect of each of the internal fluid pivotal in the load paths and powers, final tube wall loading paths have been identified on the pressure and axial regions forming and powers and failure scheme. li h.y., et al., 2015[6], studied the problem of the match of axial force and internal pressure, the results of experimental on the influence of loading path on hydroforming rusul abdulkareem al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 5266 (2018) 53 square hollow component was premised. hani aziz ameen et al., 2016[7], studied the analytical model to analyze the stress state and wrinkling in the x-branch bulging tube during the hydroforming process using ansys ls-dyna. hani aziz ameen et al.,2016[8], studied the effect of die cavity configuration on the stress distribution in tube hydroforming process with and without rubber media. in this study the effect of the dies configuration (square, cosine, and conical) and pressure (hydraulic fluid and rubber (natural and industrial)) on the bulging process with the parameters (pressure, strain, thickness, and bulging height). dies design three dies are manufactured with (square, cosine, and conical) configuration for bulging process that used hydraulic or rubber (natural and industrial) media. also a die for preparation the rubber is manufactured as shown in fig. 1. (a) rubber’s die preparation (b) square bulge die (c) cosine bulge die (d) conical bulge die fig.1. dies configurations. in order to obtain the relationship between bulge height, thickness and pressure. a square grid was etched on each tube to measure the hoop and the longitudinal strain at the end of the process so to verify the deformations calculated by the fem model via ansys. fig. 2 presents the copper tubes at the end of the experimental process. the bulge area is plastically deformed. during the test the axial plungers are still and the tube is fully blocked. the experiments design starts from the observation of the tube bursting pressure and yield pressure. within this range other different pressure levels have been investigated. for each of the tested tube, the bulge height, the radius of curvature in the longitudinal direction and the wall thickness were measured. (a)square tube (b) cosine tibe (c) conical tube fig. 2. bulging product’s tube. cases studied firstly the internal pressure is investigated for different configurations (square, cosine, and conical) die's shape. table (1) illustrated the comparison between theoretical (ref.[9]) and experimental results of internal pressure. good agreement is evident between the results. table1, the values of internal pressure. case internal pressure theoretical (mpa). ref.[9] internal pressure experimental (mpa) error% square hydraulic media 31.0656 37 16.0389 cosine 24.41418 26 6.0969 conical 25.8974 30 13.6753 rusul abdulkareem al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 5266 (2018) 54 2. bulging die with square configuration in the square die the maximum equivalent stress without rubber was 201.789mpa and maximum strain 0.34456 as shown in fig. 3 and 4 when using rubber the maximum equivalent stress was 196.029mpa and maximum strain 0.315487 as shown in fig. 5 and 6, from that it can be shown that the equivalent stress of tube’s wall in case of rubber media is about 2.8544% smaller than when using hydraulic fluid. (a) equivalent stress (b) equivalent strain fig. 3. square die without rubber. fig. 4. tube using hydraulic media. (a) equivalent stress (b) equivalent strain fig. 5. square die with rubber. fig. 6. tube using rubber media. 2.1. bulging height of square die fig.7 showed the experimental and numerical results for bulging height against pressure when the hydraulic is a pressure media at experimental and numerical test. good agreement is evident between these results. it can be seen that increasing of hydraulic the pressure 9mpa with no bulge height and the tube wall deform after 9mpa with ramp behavior. fig.8 shown the experimental and numerical results for bulging height against pressure when the natural rubber is a pressure media at experimental and numerical test. good agreement is evident between these results. it can be seen that increasing the pressing of natural rubber, the pressure increased to 10mpa with no bulge height and the tube wall deform after 10mpa with ramp behavior. fig. 9 shown the numerical results for bulging height against pressure when the industrial rubber is a pressure rusul abdulkareem al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 5266 (2018) 55 media. it can be seen that for increasing the pressing of industrial rubber the pressure increased to 14mpa with no bulge height and the tube wall deform after 14mpa with ramp behavior. figs. 7,8,9 illustrated that there are different in the behavior of pressure with bulge height vs the pressure media. hence it seen that it's higher with rubber and lower with hydraulic, and in case of industrial rubber higher than the natural rubber, and also the applying load are altered in case of hydraulic and rubber as shown since in the case of rubber the friction forces with the tube’s wall are generated. fig. 7. pressure with bulge height hydraulic media. fig. 8. pressure with bulge height -rubber media. fig. 9. pressure with bulge height industrial rubber. 2.2. strain distribution fig. 10 to15 illustrated circumferential and axial strains evaluated experimentally using grid (2 or 4) mm, and numerically by ansys software, it's seen that values of strains are constant within (2-8)mm, increasing within (1014) and decreasing in the range (16-22)mm and then constant with the period (24-88)mm after that it's increasing within (90-96)mm and decreasing within (100-103)mm, constant within (104110)mm, and it's shown symmetry about the middle. good agreement is evident between these results with average discrepancy 0.6623% for ε1 and 2.4861% for ε2 as shown in figs.10 and 11 for hydraulic media. also similar influences take place for natural rubber media as shown in fig. 12 and 13, with average discrepancy 1.1848% for ε1 and 1.0426% for ε2, while in case of industrial rubber the results observed have the same behavior as shown in figs. 14 and 15. due to bulging, the metal is flow and causing alteration in strains with continuous applying the load. fig. 10 to 15 it can be seen that the strains are began to increase in the region of bulging zone. fig. 10. ε1 with length hydraulic media. fig. 11. ε2 with length -hydraulic media. rusul abdulkareem al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 5266 (2018) 56 fig. 12. ε1 with length natural rubber media fig. 13. ε2 with length with natural rubber media. fig. 14. ε1 with length -industrial rubber media. fig. 15. ε2 with length industrial rubber media. 2.3. wall thickness distribution figs. 16 to 18 shown thickness distributions and location of thinning in the bulge test of copper tube. the tendency is reproduced but errors can be observed. the wall thickness is measured in the experiments by projector profile device, the tube is cutting in longitudinal direction. it can be seen that the behavior of the thickness against distance is not smooth, i.e. it's seen that values of thickness constant within (2-8)mm, decreasing within (1014)mm and increasing in the range (16-22)mm and then constant with the period (24-88)mm after that decreasing within (90-96)mm and increasing within (100-103)mm , constant within (104110)mm, and that shown it's symmetry about middle. good agreement is evident between the experimental and numerical results. from the above discussion, it can be observed that the average discrepancy of the thickness was 0.7377% when using hydraulic and 0.4682% with natural rubber. due to bulging, the metal is flow and causing alteration in wall thickness with continuous applying the load. fig.16 to 18 shown the thickness is began to less than 1mm in the region of bulging zone. figs. 16,17,18 illustrated the distribution of wall thickness along the tube for three media; it can be observed that the thickness in case of hydraulic is less than in case of natural and industrial rubber and thickness in case of natural rubber is less than industrial rubber media. fig. 16. wall thickness -hydraulic media rusul abdulkareem al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 5266 (2018) 57 fig. 17. wall thickness -natural rubber media fig. 18. wall thickness industrial rubber media 3. bulging die with cosine configuration it’s found that in the cosine die the maximum equivalent stress without rubber 199.248mpa and maximum equivalent strain 0.289432 as shown in fig. 19 and when rubber is used the maximum equivalent stress 181.18mpa and maximum equivalent strain 0.23395 as shown in fig. 21 from that it can be shown that the equivalent stress in tube’s wall with rubber media is about 9.068% smaller than when hydraulic fluid is used. fig. 20 illustrated the bulge tube when the hydraulic media is used and fig. 22 illustrated the bulging tube when rubber media is used. (a) equivalent stress (b) equivalent strain fig. 19 cosine die with hydraulic media. fig. 20. cosine cross-section using hydraulic media. (a) equivalent stress rusul abdulkareem al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 5266 (2018) 58 (b) equivalent strain fig. 21. cosine die with rubber media. fig. 22. cosine cross-section using rubber media. 3.1. bulging height of cosine die fig. 23 shown the experimental and numerical results for bulging height against pressure when the hydraulic is a pressure media. good agreement is evident between these results. from this figure, it can be observed that increasing of hydraulic pressure to 2mpa with no bulge height and the tube wall deform after 2mpa with ramp behavior. fig. 24 shown the experiment and numerical results for bulging height against pressure when the natural rubber is a pressure media. also good agreement is evident between these results. from this figure, it can be seen that increasing the pressure due to natural rubber media to 10mpa with no bulging height and the tube wall deform after 10mpa with ramp behavior and when the industrial rubber is used, the pressure increased to 30mpa with no bulging height and the tube wall deform after 30mpa with ramp behavior as shown in fig. 25. good agreement is evident with ansys results. figs. 23,24,25 illustrated that there are different in the behavior of pressure with bulge height with the pressure media. hence it seen that it's higher with rubber and lower with hydraulic, higher with industrial rubber than natural rubber, and also the applying load are altered in case of hydraulic and rubber as shown that because of, in the case of rubber the friction forces against the tube wall is generated . fig. 23. pressure with bulgeheight hydraulic media. fig. 24. pressure with bulge height-natural rubber. fig.25. pressure with bulge height industrial rubber 3.2. strain distribution figs. 26 to 31 illustrated circumference and axial strains evaluated experimentally using grid (2 or 4) mm, and numerically by ansys software, it's seen that the values of strain remain constant within range (2-24) mm and increasing in the range (26-60)mm and then decreasing within period (62-96)mm after that the strain is seen constant within (98-120)mm, and it's shown symmetry about the middle, when hydraulic rusul abdulkareem al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 5266 (2018) 59 media is used. the average discrepancy 0.3327% for ε1 and 0.7735% for ε2 as shown in figs. 26 and 27. also similar influences take place for natural rubber media as shown in figs. 28 and 29, with average discrepancy 1.2706% for ε1 and 1.0022% for ε2, while in case of industrial rubber the results observed the same behavior as shown in figs. 30 and 31. due to bulging, the metal is flow and that causes alteration in strain with continuous applying the load. from fig. 26 to 31 it can be seen that the strains are began to increase in the region of bulging zone. fig. 26. ε1 with length distancehydraulic media. fig. 27. ε2 with length distance hydraulic media. fig. 28. ε1 with length -natural rubber media. fig. 29. ε2 with length -natural rubber media. fig. 30. ε1 with length industrial rubber media. fig. 31. ε2 with industrial rubber media. 3.3. wall thickness distribution figs. 32 to 34 shown thickness distributions and location of thinning in the bulge test for copper tube. the tendency is reproduced but errors can be observed. the thickness of wall tube is measured experimentally by projector profile device, that cutting the tube it in longitudinal. it can be seen that the behavior of the thickness against distance is not smooth, i.e. it's seen that the values of thickness remain constant within (224) mm and decreasing in the range (26-60)mm rusul abdulkareem al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 5266 (2018) 60 and then increasing within period (62-96)mm after that the thickness is observed constant and it’s symmetry about the middle. good agreement is evident between the experimental and numerical results. from the above discussion, it can be deduced that the average discrepancy of the thickness was 0.5788% when hydraulic is used and 0.531% when natural rubber is used. due to bulging, the metal is flow and that causes alteration in wall thickness with continuous applying the load. figs. 32 to 34 shown that the thickness is began to less than 1mm in the region of bulging zone. figs. 32,33,34 illustrated the distribution of wall thickness along the tube for three media; it can be seemed that thickness in case of hydraulic media is less than in case of natural rubber media and when the industrial rubber is used the wall thickness increased against natural rubber media. from fig. 32 to 34 and fig. 20 it can be deduced that the relationship between the cosine shape with variation of bulging height and wall tube thickness will be: � = ��� ��� − �) + ��� − �))� + � � ��� − �) − ��� − �))� � ��.�� � … (1) ε1 circumferential strain ε2 axial strain r1 maximum radius of die r2 minimum radius of die t alternation thickness with bulging radius. z length of section on die length l bulging die length fig. 32. wall thickness hydraulic media fig. 33. wall thickness -natural rubber media fig. 34. wall thickness industrial rubber media 4. bulging die with conical configuration in the conical die the maximum equivalent stress with hydraulic media is 202.224mpa and maximum equivalent strain is 0.224223 as shown in fig.35 and when using rubber as a media the maximum equivalent stress is 191.215 mpa and maximum equivalent strain is 0.690767 as shown in fig. 37. from that it can be shown that the wall tube equivalent stress when the rubber media is used is about 5.4439% smaller than when hydraulic fluid is used. fig. 36 illustrated the bulging tube when the hydraulic media is used and fig. 38 illustrated the bulging tube when used rubber media. rusul abdulkareem al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 5266 (2018) 61 (a) equivalent stress (b) equivalent strain fig. 35. conical die with hydraulic media. fig. 36. tube with conical section using hydraulic. (a) equivalent stress (b) equivalent strain fig. 37. conical die with rubber media. fig. 38. conical section using hydraulic media. 4.1. bulging height of conical die fig. 39 shown the experimental and numerical results for bulging height against pressure when the hydraulic is a pressure media. good agreement is evident between the results and it can be seen that increasing of hydraulic the pressure increased to 2mpa with no bulging height and the tube wall deformed after 2mpa with ramp behavior. fig. 40 shown the experimental and numerical results for bulging height against pressure when the natural rubber is a pressure media. figs.40 and 41, observed the behavior of natural and industrial rubber is the same that the pressure increased to 20mpa with no bulging height and the tube wall deformed after 20mpa with ramp behavior. good agreement is evident with ansys results. figs. 39, 40, 41 illustrated that there are different in the behavior of pressure with bulging height with the pressure media. hence it seen that it's higher with rubber and lower with hydraulic medias, industrial rubber higher than natural rubber media, and also the applying loads are altered in case of hydraulic and rubber medias as shown that because in case of rubber media the friction forces with the tube wall is generated . rusul abdulkareem al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 5266 (2018) 62 fig. 39. pressure with bulge height hydraulic media fig. 40. pressure with bulge height natural rubber fig.41. pressure with bulge height industrial rubber 4.2 strain distribution figs.42 to 47 illustrated circumference and axial strains evaluated experimentally using grid (2 or 4) mm, and numerically by ansys software, it's seem that the values of strain remain constant within (2-42)mm and increasing in the range (44-74) mm and then decreasing with period (76-95)mm after that the strain is seen to be constant within (95-114)mm, and it’s shown not symmetry about the middle when it’s using hydraulic media. good agreement is evaluated between these results with average discrepancy 1.3879 % for ε1 and 1.2918% for ε2 as shown in figs. 42 and 43. also similar influences take place for natural rubber media as shown in figs. 44 and 45, with average discrepancy 1.0623% for ε1 and 0.7205% for ε2, while in case of industrial rubber media the results had the same behavior of the figs. 46 and 47. fig. 42. ε1 with length hydraulic media. fig. 43. ε2 with length hydraulic media. fig. 44. ε1 with length -natural rubber media. rusul abdulkareem al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 5266 (2018) 63 fig. 45. ε2 with length -natural rubber media. fig. 46. ε1 with length industrial rubber media. fig. 47. ε2 with length -industrial rubber media. 4.3. wall thickness distribution figs. 48 to 50 shown thickness distributions and the location of thinning in the wall of copper tube. the tendency is reproduced but errors can be observed. the wall thickness is measured in the experiments by projector profile device, the tube is cutting in the longitudinal direction. it can be seen that the behavior of the thickness against distance is not smooth, i.e. it's seem that the values of thickness remain constant within (242)mm and decreasing in the range (44-74) mm and then increasing with period (76-84)mm after that the thickness is seen to be constant and that shown it’s not symmetry about the middle. good agreement is evident between the experimental and numerical results. from the above discussion, it can be observed that the average discrepancy of the thickness was 0.611% when using hydraulic media and 0.4812% with natural rubber media. due to bulging, the metal is flow and that causes alteration in wall thickness with continuous applying the load. figs. 48 to 50 it can be observed that the thickness is began to less than 1mm in the region of bulging zone. figs. 48,49,50 illustrated the distribution of wall thickness along the tube for three media; it can be seemed that the thickness in case of hydraulic media is less than in case of the natural rubber media and industrial rubber media and thickness in case natural rubber media is less than industrial rubber media. fig. 48. wall thickness -hydraulic media fig. 49. wall thickness -natural rubber media rusul abdulkareem al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 5266 (2018) 64 fig. 50. wall thickness industrial rubber media as the results, the comparison of the maximum equivalent stresses value for the numerical simulation is made for the three dies with and without rubber table (2) illustrated that. it is found that the stress decreased about 9.068% when the natural rubber is the media of the internal pressure in case of cosine die and 5.4439% in case of conical die and 2.8544% in case of square die. so it can be concluded that the rubber media used in bulging tube is much better than the hydraulic fluid, and from the experimental results , it can be concluded that the force for forming the shape using rubber media is higher than the hydraulic media and the force that needed to form by industry rubber media is higher than that foe natural rubber media. table 2, the differences in equivalent stresses with hydraulic media and with natural rubber media bulge configuration equv. stress with hydraulic [mpa] equv. stress with natural rubber [mpa] error % cosine 199.248 181.18 9.068 conical 202.224 191.215 5.4439 square 201.789 196.029 2.8544 in case of hydraulic media, the forming pressure needed to bulging process is less when with the rubber media but with height stress in the tube metal, and that let to cause the failure, while in case of rubber media, the forming pressure that needed to bulging process is higher using the hydraulic media but with less stress in tube metal, and the failure is not existed with rubber media for the same pressure of hydraulic. fig. 51 illustrated that. it can be indicated that the crack happened in the tube is type i (open crack) in cosine die. (a)with hydraulic media (b) with natural rubber media fig. 51. bulging tube with and without rubber. 5. conclusions 1. it's found that the stress is decreased about 9.068% in the rubber media in case of cosine die and 5.4439% in the rubber media in case of conical die and 2.8544% in the rubber in case of square die. so it can be concluded that internal pressure in the rubber media is much better than in hydraulic media. 2. in case of hydraulic, the lower forming pressure is needed to bulging process compared with the rubber media since height stress in the tube metal is existed. which causing the failure, while in case of rubber, the forming pressure that needed to bulge process is higher when compared with the hydraulic media but with less stress in tube metal and the failure is not existed with rubber media for the same pressure of hydraulic. 3. the average discrepancy of the thickness is 0.7377% in the hydraulic media and 0.4682% in the rubber media in case of square die, and the average of discrepancy of the thickness is 0.5788% in the hydraulic media and 0.531% in the rubber media in case of cosine die, and it found the average discrepancy of the thickness is 0.611% in the hydraulic media and 0.4812% in the rubber media in case of conical die. 4. it’s found the maximum thinning of the thickness is 28.64%,when the hydraulic media ,16.8% when the natural rubber media and 15.2% when the industrial rubber media in case of square die, and it’s found the maximum thinning of the thickness is 32.5%,when the hydraulic media ,29.4% when the natural rubber media and 27.4% when the industrial rubber media in case of cosine die, and it’s found the maximum thinning of the thickness is 27.9%,when the hydraulic media rusul abdulkareem al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 5266 (2018) 65 ,22.4% when the natural rubber media and 20.6% when the industrial rubber media in case of conical die. 5. the distribution of tube wall thickness in case of rubber media is better than that for hydraulic media also it can be concluded that for industrial rubber is better than that for natural rubber. 6. the internal pressure when used the hydraulic media it’s found the discrepancy between theoretical and experimental 16.0389% when used square die, the discrepancy 6.0969% when used cosine die , and the discrepancy 13.6753% when used conical die. acknowledgements we would like to express my deepest gratitude to the staff of the middle technical university/ engineering technical college/baghdad – dies and tools technical engineering department for their support to complete this work. 6. references [1] girard a.c., grenier y.j., mac donald b.j.," numerical simulation of axisymmetric tube bulging using a urethane rod" ,journal of materials processing technology, 172, pp346– 355,2006. [2] sadiq jaffar aziz, "experimental and numerical study of tubes hydroforming process", ph.d. thesis, department of production engineering and metallurgy, university of technology 2008. [3] selvakumar a. s., kalaichelvan k., and venkataswamy s., "effect of heat treatment process on hydroforming of tubular materials", european journal of scientific research, vol.68, no.3, pp. 377-388, 2012. [4] sami abbas hammood, " numerical and experimental analysis of tube hydroforming in a square crosssectional die", m.sc. thesis, university of technology, production engineering and metallurgy department,137 pages, 2012. [5] emad jabour yousif, "experimental study for tube hydroforming" ,m.sc. thesis, university of tikrit, 2013. [6] li h.y., yu z.j., li j.h. and liu m., "experimental research of hydroforming square hollow component", international conference on mechatronics, electronic, industrial and control engineering ,meic 2015. [7] hani aziz ameen, kadhim mijbel mashloosh, rusul abdel kareem salman, " effect of loading path on the stress distribution and wrinkling in x-branch type tube hydroforming", international journal of engineering research & technology (ijert), issn: 2278-0181 vol. 5 issue 07, july-2016. [8] hani aziz ameen, kadhim mijbel mashloosh, rusul abdel kareem salman, " effect of die cavity configuration on the stress distribution in tube hydroforming process with and without rubber media ", international journal of scientific & engineering research, issn 22295518,volume 7, issue 9, september-2016. [9] asnafi, n. , “analytical modeling of tube hydroforming”, thin-walled struct., 34, pp: 295–330, 1999. )2018( 52-66، صفحة1د، العد14دجلة الخوارزمي الهندسية المجلم رسل عبد الكريم سلمان 66 دراسة وسط التشكيل في عملية التشكيل الهيدروليكي ألنبوب النحاس ***مشلوشكاظم مجبل ** هاني عزيز أمين رسل عبدالكريم سلمان* بغداد -الكلية التقنية الهندسية rusulalizee@gmail.com*البريد االلكتروني: haniazizameen@yahoo.com**البريد االلكتروني: kadm52@yahoo.com***البريد االلكتروني: ___________________________________________________________ الخالصة الضغط تم دراسة تأثير أوساط الضغط الداخلي على توزيع األجهاد المكافئ في األنبوب , وتم أجراء الدراسة العملية من خالل بناء نظام لتطبيق ansysج الهيدروليكي وتصنيع ثالثة قوالب مع تكوين انتفاخات تشكيل مختلفة (مربع وتقوس بشكل جيب تمام و مخروطي الشكل ) . وتم أستخدام برنام تبين أن األجهادات تقل الى لتحليل عملية النفخ مع األوساط الهيدروليكية والمطاط ( الطبيعي والصناعي). apdlمن خالل برمجة الحاالت أعاله بأستخدام الة القالب ذو تجويف في ح %5.4439عند أستخدام المطاط كوسط للضغط الداخلي في حالة أستخدام قالب ذو تجويف الجيب تمام و %9.068حوالي في حالة القالب ذو الشكل المربع. لذلك يمكن أن نستنتج الى أن أوساط المطاط المستخدمة في أنتفاخ األنبوب هو أفضل بكثير من %2.8544مخروطي و روليكية والقوة التي نحتاجها للتشكيل بواسطة األوساط الهيدروليكية, وتم أستنتاج عمليا أن قوة التشكيل التي نحتاجها للتشكيل بوجود المطاط أعلى من الهيد وتم استنتاج ان توزيع السمك لجدار األنبوب في حالة أستخدام وسط المطاط أفضل من أستخدام المطاط الصناعي أعلى من قوة التشكيل بالمطاط الطبيعي. وبينت الدراسة انه في حالة الهيدروليك , فأن قيمة ضغط لب.وسط الهيدروليك وأستخدام وسط المطاط الصناعي أفضل من المطاط الطبيعي في نفس القا لفشل , بينما في حالة التشكيل المحتاج لعملية األنتفاخ أقل مقارنة مع أوساط المطاط بينما وجد أن األجهادات كانت عالية بمعدن االنبوب والتي تسمح لحدوث ا لى مقارنة من األوساط الهيدروليكية ولكن مع أجهاد أقل في معدن االنبوب. و هذا بالتأكيد يوضح المطاط , وجد أن ضغط التشكيل المحتاج لعملية األنتفاخ أع عدم حدوث الفشل في جدار االنبوب باستخدام أوساط المطاط لنفس الضغط بوجود الوسط الهيدروليكي. ________________________________________________________________________________________________ performance of turbo-codes with ahmed s. hadi /al-khwarizmi engineering journal ,vol.2, no. 2 pp 1-14 (2006) 1 performance of turbo-codes with some proposed interleaver schemes ahmed s. hadi information &communications engineering dept. al khwarizmi college of engineering university of baghdad (received 14 november 2005; accepted 4 april 2006) abstract: this paper describes a number of new interleaving strategies based on the golden section. the new interleavers are called golden relative prime interleavers, golden interleavers, and dithered golden interleavers. the latter two approaches involve sorting a real-valued vector derived from the golden section. random and so-called “spread” interleavers are also considered. turbo-code performance results are presented and compared for the various interleaving strategies. of the interleavers considered, the dithered golden interleaver typically provides the best performance, especially for low code rates and large block sizes. the golden relative prime interleaver is shown to work surprisingly well for high puncture rates. these interleavers have excellent spreading properties in general and are thus useful for many applications other than turbo-codes. keywords: fec, turbo code, interleaver, golden section, relative prime. 1. introduction interleaving is a key component of many digital communication systems involving forward error correction (fec) coding. this is especially true for channels characterized by fading, multipath, and impulse noise, for example. interleaving, or permuting, of the transmitted elements, provides time diversity for the fec scheme being employed. an element is used here to refer to any symbol, sample, digit, or bit that is interleaved. in the past the interleaving strategy was usually only weakly linked to the fec scheme being employed. exceptions are concatenated fec schemes such as concatenated viterbi and reed-solomon decoding. the interleaver is placed between the two fec encoders to help spread out error-bursts and the depth of interleaving is directly linked to the error correction capability of the inner (viterbi) decoder. more recently, however, interleavers have become an integral part of the coding and decoding strategy itself. such is the case for turbo and turbo-like codes, where the interleaver is a critical part of the coding scheme. the problem of finding optimal interleavers for such schemes is really a code design problem, and is an on-going area of research. one problem with classical interleavers is that they are usually designed to provide a specific interleaving depth. this is fine if each al-khwarizmi engineering journal al-khwarizmi engineering journal, vol.2, no.2, pp 1-14 (2006) ahmed s. hadi /al-khwarizmi engineering journal ,vol.2, no. 2 pp 1-14 (2006) 2 burst of errors never exceeds the interleaver depth, but it is wasteful if the interleaver is overdesigned (too long) and error-bursts are typically much shorter than the interleaver depth. for example, a simple 10x10 matrix interleaver has an interleaving depth of 10 elements. if a burst of 10 errors occurs, the deinterleaver will optimally spread these 10 errors throughout the block of 100 elements. if the error-burst is 11 elements long, however, then two errors will again be adjacent. if the error-burst is only two elements long then these two errors will only be spaced 10 elements apart after deinterleaving, but they could have been spaced much further apart if it was known that only two errors were present. for example, a 2x50 matrix interleaver would have spaced these two errors 50 elements apart. of course this interleaver is not good for longer bursts of errors. in practice, most channels usually generate error events of random length, and the average length can be time varying, as well as unknown. this makes it very difficult to design optimum interleaving strategies using the classical approaches. what is sought is an interleaving strategy that is good for any errorburst length. section 2 provides some background on turbocodes and interleaving methods. section 3 describes the new interleaving strategies based on the “golden section”. section 4 compares the bit and packet error-rate performance of turbocodes with the various interleavers. section 5 gives the conclusions. 2. background turbo-codes [1,2,3] have received considerable attention since their introduction in 1993. this is due to their powerful error correcting capability, reasonable complexity, and flexibility in terms of providing different block sizes and code rates. the canonical turbo-code encoder consists of two 16-state, rate 1/2 recursive systematic convolutional (rsc) encoders operating in parallel with the information bits interleaved between the two encoders, as shown in figure 1. without puncturing, the overall code rate is 1/3. this is because the systematic information bits are only sent once. other code rates can be achieved as required by puncturing the parity bits c 1 k and c 2 k . it is the job of the interleaver to break apart low-distance error patterns that belong to one rsc code, in the hope that they will create high-distance error patterns in the other rsc code. a number of close-to-optimum and suboptimum turbo decoding methods are possible. the simulation results presented here are based on the enhanced maximum-log-a-posterioriprobability (max-log-app) approach, with corrected extrinsic information, as described elsewhere in [3, 4,5,6]. it has been found that performance is typically within 0.1 to 0.2 db of exact, infinite precision log-app decoding. the amount of degradation is a function of block size, code rate, and signal-to-noise ratio (snr), with the larger degradations occurring for long blocks, low code rates, and low snrs. it is convention that one turbo decoding iteration be defined as two max-log-app decoding operations. interleaving is a key component of any turbo-code, as shown in figure 1. although some form of random or pseudo-random interleaving is usually recommended, it has been found that simple structured interleavers can also offer good performance, especially for short data blocks on the order of a few hundred bits. examples of common structured block interleavers include relative prime interleavers and lm matrix (or block) interleavers using l rows and m columns. an lm matrix interleaver is usually implemented by writing into the rows and reading out of the columns, or vice versa. the rows or columns are sometimes read in or out in a permuted order. this permuted order is often implemented using a relative prime. that is, the row or column index can be generated using modulo arithmetic where the index increment and row or column lengths are relative primes. with l or m equal to 1, this type of interleaver simply becomes a one-dimensional relative prime interleaver. ahmed s. hadi /al-khwarizmi engineering journal ,vol.2, no. 2 pp 1-14 (2006) 3 the relative prime interleaver is examined more closely in section 3. the original “turbo” interleaver [1,2] is based on the use of an mm matrix with a form of (pseudo-random) relative prime indexing, but the design is much more complicated than that described above. this interleaver has been reported to work well, but is not suited to arbitrary block sizes. this interleaver is not considered further in this paper, but the approach definitely merits further investigation. two other interleavers that have been investigated are the “random” interleaver, and the so-called “spread” interleaver [7,8,9]. the random interleaver simply performs a random or pseudo-random permutation of the elements without any restrictions. this interleaver is very useful as a benchmark, and has also been used extensively in calculating error-rate bounds [8,9]. the spread interleaver is really a semirandom interleaver. it is based on the random generation of n integers from 0 to n-1, but with the following constraint [7,9]: each randomly selected integer is compared to the s most recently selected integers. if the current selection is within s of at least one of the previous s integers, then it is rejected and a new integer is selected until the previous condition is satisfied. this process is repeated until all n integers are extracted. the search time increases with s, and there is no guarantee that the process will finish successfully. as a rule of thumb the choice s < 2 n produces a solution in a reasonable amount of time. a number of variations on the spread interleaver are presented in [10,11,12,13]. these variations are not considered further here, but also merit further investigation. 3. golden section interleaving 3.1 the golden section the golden section arises in many interesting mathematical problems. figure 2 illustrates the golden section principle in relation to the interleaving problem of interest. given a line segment of length 1, the problem is to divide it into a long segment of length g, and a shorter segment of length 1-g, such that the ratio of the longer segment to the entire segment is the same as the ratio of the shorter segment to the longer segment. that is, 1 g = g g1 (1) g= 2 15  =0.618 (2) now consider points generated by starting at 0 and adding increments of g, using modulo-1 arithmetic. after the first increment there are two points at 0 and g that are 1-g apart, using modulo-1 arithmetic. modulo distances are used to allow for the option of having the first point start anywhere along the line segment. from (1), the distance of 1-g is the same as g 2 . after the second increment the first and third points determine the minimum distance and this distance is g 3 . again, this follows from the definition of g in (1). after the third increment the first and fourth points determine the minimum distance and this distance is g 4 . the minimum distance after the fifth point is the same. the minimum distance after the sixth point is g 5 . this trend continues, with the minimum distance never decreasing by more than a factor of g when it does decrease. this property follows directly from the definition of the golden section in (1). the same distances can also be generated with the complement increment of (1-g)=g 2 0.382. higher powers of g can also be used for the increment value, but the initial minimum distances are reduced to the smaller increment value. figure 3 shows a plot of the minimum distances versus the number of points considered, as points are added using an increment of g with modulo-1 arithmetic. ahmed s. hadi /al-khwarizmi engineering journal ,vol.2, no. 2 pp 1-14 (2006) 4 figure 3 also shows an upper bound for each specific number of points. that is, given n points, and only n points, they could be uniformly spaced with a minimum distance of 1/n. of course the golden section increment results are valid for all numbers of points at the same time. the upper bound is not. even so, the golden section increment results are seen to track the upper bound quite closely. note that even when the minimum distance drops, most points will still be at the previous minimum distance from their neighbours, with the average distance between points equal to the upper bound. the distance properties of the golden section increment, illustrated in figure 3, are desirable for interleavers in general, but in particular are desirable for turbo-code interleavers. it is now shown how these properties can be used in designing a number of practical interleavers. 3.2 golden relative prime interleavers for golden relative prime interleavers, the interleaver indexes are calculated as follows:  (i)= (s + i.t) modl_info,i=0…l_info-1 (3) where s is an integer starting index, t is an integer index increment, and l_info is the interleaver length. l_info and t must be relative primes to ensure that each element is read out once and only once. the starting index s is usually set to 0, but increment, s, is chosen “close” (as further defined below) to one of the non-integer values of c=l_info(g m +j)/r (4) where g is the golden section value, m is any positive integer greater than zero, r is the index spacing (distance) between nearby elements to be maximally spread, and j is any integer modulo r. the preferred values for m are typically 1 or 2. in a typical implementation where adjacent elements are to be maximally spread, j is set to 0 and r is set to 1. for turbocodes, however, greater values of j and r can be used to obtain the best spreading for elements spaced r apart. for example, r could be set to the repetition period of the feedback polynomial in the rsc encoder, to maximally spread input-weight-2 error events. one definition of being a “close” relative prime is to fall within a small window about the exact real value, c, given in (4). the simplest choice is to select the relative prime t closest to c, for predetermined values of l_info, m, j, and r. the result is a golden relative prime interleaver with quantization error. for large blocks the quantization error is usually not significant for short error-burst lengths, but can grow to be significant after many increments. one way to mitigate the quantization error problem is to perform a search for the best relative prime increment t in the vicinity of c, by using the minimum distance between interleaved indexes for the maximum number of elements considered, as a measure of the spreading quality of the interleaver. alternatively, the best relative prime increment, t, in the vicinity of c, is determined by the sum (or weighted sum) of the minimum distances between interleaved indexes for all numbers from two up to the maximum number of elements considered. in this case, the best choice for t is that which maximizes the area under the minimum distance curve. figure 4 shows the spreading properties for an interleaver having a size l_info=1028 (e.g. used in a turbo-code encoder with 1024 information bits and 4 flush bits per block), m=2, j=0, r=1, and a relative prime increment of t=393. the value of c=l_info g 2 is approximately 392.7. the value of p=393 is the closest relative prime. as can be seen, this golden relative prime interleaver performs well in tracking the upper bound near the origin, but does not appear to be as good away from the origin where the accumulating quantization error becomes significant. the area under the entire curve is 4620. this spreading measure is used for comparison purposes below. most general purpose digital signal processors (dsps) today offer the kind of modulo indexing indicated in (3) to implement circular buffers. it is also trivial to implement in hardware. thus, ahmed s. hadi /al-khwarizmi engineering journal ,vol.2, no. 2 pp 1-14 (2006) 5 golden relative prime interleavers require no additional memory and little or no additional processing compared to that required to store and read an uninterleaved vector. 3.3 golden interleavers golden interleavers do not use integer relative primes and integer modulo arithmetic, but rather are based on sorting real-valued numbers derived from the golden section. the first step is to compute the golden section value g. the second step is to compute the real increment value c, as defined previously in (4). the third step is to generate real-valued golden vector v. the elements of v are calculated as follows: v(i)=(s + i. c),mod l_info,i=0…l_info-1 (5) where s is any real starting value. the next step is to sort golden vector v and find the index vector z that defines this sort. that is, find sort vector z such that a(i)=v(z(i)), i=0…l_info-1, where a=sort(v). the golden interleaver indexes are then given by  (z(i))=i, i=0…l_info-1. in fact, vector z is the inverse interleaver for  . the starting value s is usually set to 0, but other real values of s can be selected. the preferred values for m are typically 1 or 2, as discussed previously. for maximum spreading of adjacent elements, j is set to 0 and r is set to 1. for turbo-codes, greater values of j and r may be used to obtain the best spreading for elements spaced r apart, as discussed previously. the golden interleaver does not suffer from accumulating quantization errors, as does the golden relative prime interleaver. in the golden interleaver case, a quantization error only occurs in the final assignment of the indexes. on the other hand, the golden interleaver cannot be implemented using the simple modulo-increment indexing method described above for the golden relative prime interleaver. in contrast, the golden interleaver indexes must be pre-computed and stored in index memory for each block size of interest. if the full indexes are stored, then the index memory can be excessive. for example, an interleaver of length 216 elements would require 162 16 bits of index memory. the required amount of index memory can be significantly reduced by only storing index offsets. for example, the n-th index can be ea sily calculated as required using  (i)=floor[v(i)]+o(i), where the floor function extracts the integer part, v(n) is calculated using real mod l_info arithmetic as in (5), and by definition o(n) is the required index offset stored in index memory. the number of bits that are required to store each index offset is typically only one or two. thus, for the example above, the index memory is reduced to 22 16 bits, or about 1/8 that required for full storage of the indexes. figure 5 shows the spreading properties for a golden interleaver having size l_info=1028, m=2, j=0, and r=1. the value of real increment c= l_infog 2 is approximately 392.7. as can be seen from figure 5, the golden interleaver performs very well in tracking the theoretical upper bound, and tracks it better than the golden relative prime interleaver curve shown in figure 4. note that the area under the curve has increased from 4620, for the golden relative prime interleaver, to 5250, for the golden interleaver, indicating that the golden interleaver is better at spreading out error-bursts of arbitrary length. 3.4 dithered golden interleavers it has been found for turbo-codes that interleavers with some randomness tend to perform better than completely structured interleavers, especially for large block sizes on the order of 1000 or more bits. however, the spreading properties of the golden interleaver are still very desirable, both to maintain a good minimum distance (a steep error curve at high snrs) and to ensure rapid convergence by efficiently spreading error-bursts throughout the block. these two features are encompassed in the dithered golden interleaver. the only difference between the golden interleaver and the dithered golden interleaver is the inclusion ahmed s. hadi /al-khwarizmi engineering journal ,vol.2, no. 2 pp 1-14 (2006) 6 of a real perturbation (dither) vector d, in golden vector v. that is, v(i)=(s+i.c+d(i),mod l_info,i=0…l_info-1, (6) where d(i) is the i-th dither component. the added dither is uniformly distributed between 0 and l_info d, where d is the normalized width of the dither distribution. the dithered golden vector v is sorted, and interleaver indexes are generated in a similar manner to that for the golden interleaver described above. it has been found experimentally, for turbo-codes, that a crude rule of thumb for any block size is to use d0.01. the result is that for small blocks, on the order of 1000 bits or less, the effect of the dither component is small. for large blocks, on the order of 1000 bits or more, the effect of the dither component naturally increases as the block size increases. in practice, the optimum amount of dither for a specific turbo-code is a function of the block size and the code rate obtained with puncturing. similar to the golden interleaver, the dithered golden interleaver requires the use of index memory for storing pre-computed indexes, and therefore cannot be implemented using the simpler method of modulo-increment indexing. as for the golden interleaver, the required amount of index memory can be significantly reduced by only storing index offsets. the amount of memory required now depends on the degree of dither, and whether the dither component is included in the calculation of each approximate index, or whether it is totally accounted for in the stored index offset. in conclusion, the dithered golden interleaver maintains most of the desirable spreading properties of the golden interleaver, but is also capable of adding randomness to the interleaver to improve turbo-code performance. further, the golden interleaver is now just a special case of the dithered golden interleaver with d=0. 3.5 performance results performance results are presented for a fixed interleaver size of l_info=1028 (historically selected for a 1024 info-bit block with 4 flush bits). the turbo-code uses two identical, parallel, 16-state, rate 1/2 rsc codes, with polynomials (23,35) 8 . the repetition period of the feedback polynomial is r=15. results are presented for nominal code rates of 1/3 (unpunctured), 1/2 and 4/5. the turbo decoding method used is the enhanced maxlog-app (a posterior probability) approach presented in [5,6]. this method typically provides performance with 0.1 to 0.2 db of exact, infinite precision app processing. the maximum number of decoding iterations was set to 16. a simple early stopping criterion was used, which helped speed up the simulations [5 ]. a more extensive list of the encoder and decoder specifications is given in [6]. the rsc code trellis termination method is critical to the performance of turbocodes, especially with good interleavers. a number of generally applicable dualtermination and dual-tail-biting techniques are presented in [14,15]. these termination techniques do not place any restrictions on the interleaver design. the recommended approach for large blocks (>1000 info-bits) is to perform dual-termination. without termination, both rsc encoders start in the zero-state and both stop in an unknown state. with singletermination, a commonly used approach in the literature, the interleaver includes 4 flush bits, both rsc encoders start in the zero-state, and one rsc encoder is known to stop in the zerostate. with dual-termination, the interleaver includes 8 flush bits and both rsc encoders are known to start and stop in the zero-state. for large blocks the flush overhead is negligible. figure 6 shows the packet error rate (per) performance for rate 1/2 codes, with the three termination options mentioned above. the same dithered golden interleaver, with m=1, j=0, r=1, and d=0.02, was used in all three cases. this figure clearly shows the importance of proper trellis termination, when a good interleaver is used. the conclusion is quite different for a random interleaver. the bit error rate (ber) results corresponding to figure 6 ahmed s. hadi /al-khwarizmi engineering journal ,vol.2, no. 2 pp 1-14 (2006) 7 are shown in figure 7. the remaining results were all obtained with dual-termination. figure 8 shows the per results for a code rate of 1/3, and four different interleavers of size l_info=1028. the interleavers used are the “random” interleaver, the relative “prime” interleaver with t=393 (closest relative prime to l_infog 2 ), the “spread” interleaver with spread parameter s=18, and the dithered “golden” interleaver with m=1, j=0, r=1, and d=0.02. the spread interleaver address generator was obtained from [12]. as expected, the highly structured relative prime interleaver does not perform well at high snrs due to its inability to break up coupled error events. it does, however, do an excellent job of eliminating the low-distance input-weight-2 events (multiples of 15 to multiples of 15). note that the random interleaver is not much better for this block length. the spread interleaver offers a significant improvement, but the dithered golden interleaver provides the best performance. figure 9 shows the corresponding ber results. it is worth noting that the ber results for the random interleaver, at high snrs, agree quite closely with the theoretical bounds presented in [8,9]. concerning statistical reliability, 1000 packet errors were counted in the upper portion of each curve. the goal for the lowest point on each curve was to count on the order of 100 packet errors. the least reliable result is for the lowest point on figures 8 and 9, for which only 20 packet errors were counted. even so, it is safe to say that the “bend” in the ber curve, for the dithered golden interleaver, is in the vicinity of 10 10 . figure 10 shows the per results for a punctured code rate of 4/5, and the same four interleaver types. the random, relative prime, and spread interleavers were exactly the same as before. the best parameters found for the dithered golden interleaver were m=1, j=9, r=15, and d=0.005. the dithered golden interleaver is again the best. what is somewhat surprising is how well the relative prime interleaver performs. this is partly explained by the fact that, for high puncture rates, it becomes more important to eliminate lowdistance input-weight-2 events, and the relative prime interleaver is ideally suited to this task. the spread interleaver is not as effective at eliminating such events, and therefore performance is degraded. figure 11 shows the corresponding ber results. note that the bend in the ber curve occurs much higher for highly punctured codes. even so, this high rate code, with a dithered golden interleaver, still provides excellent performance for bers down to 10 7 . 4.conclusions 1. three new interleavers based on the golden section were presented. they are called the golden relative prime interleaver, the golden interleaver, and the dithered golden interleaver. random and spread interleavers were also considered. turbo-code performance results were presented and compared for the various interleavers. 2. the dithered golden interleaver provided the best performance in all cases considered. 3. the golden relative prime interleaver, although highly structured with no random component, worked surprisingly well for high code rates. 4. using a dithered golden interleaver of size l_info=1028, it was shown that a parallel, dualterminated, 16-state, rate 1/3 turbo-code can achieve a ber of 10 10 at an eb/n0 value of 1.6 db. the bend in the ber curve also occurs at a ber of about 10 10 . puncturing this same code to rate 4/5 moved the bend out and up to a ber of about 10 7 . further improvements should be possible by incorporating more specific knowledge about the punctured component rsc codes into the interleaver design. 5. the various “golden” interleavers have excellent spreading properties in general and ahmed s. hadi /al-khwarizmi engineering journal ,vol.2, no. 2 pp 1-14 (2006) 8 are thus useful for many applications other than turbo-codes 6. there are no restrictions on the block size, and a time-consuming search is not required. thus, interleavers can be easily generated on an as needed basis for any block length. 5.references [1] ber 1993, c. berrou, a. glavieux, and p. thitimajshima, “near shannon limit errorcorrecting coding and decoding: turbocodes”, proceedings of icc’93, geneva, switzerland, pp. 1064-1070, may, 1993. [2] ber 1996, c. berrou, and a. glavieux, “near optimum error correcting coding and decoding: turbo-codes”, ieee trans. on comm., vol. 44, no. 10, october 1996. [3] b. talibart and c. berrou, “notice preliminaire du circuit turbo-codeur/decodeur turbo4”, version 0.0, june, 1995. [3] aba 2002, n. h. abbas, "turbo code design for wireless communications," master's thesis, university of baghdad, iraq, november 2002. [4] cro 1998, s. crozier, a. hunt, k. gracie, and j. lodge, “performance and complexity comparison of block turbo-codes, hypercodes, and tail-biting convolutional codes”, 19-th biennial symposium on communications, kingston, ontario, canada, pp.84-88, may 31-june 3, 1998. [5] gra 1998, k. gracie, s. crozier, a. hunt, and j. lodge, “performance of a lowcomplexity turbo decoder and its implementation on a low-cost, 16-bit fixedpoint dsp”, the 10-th international conference on wireless communications (wireless’98), calgary, alberta, canada, pp.229-238, july 6-8, 1998. [6] gra 1999, k. gracie, s. crozier, and a. hunt, “performance of a low-complexity turbo decoder with a simple early stopping criterion implemented on a sharc processor”, international mobile satellite conference (imsc’99), ottawa, canada, june 16-18, 1999. [7] hun 1999, a. hunt, s. crozier, m. richards, and k. gracie, “performance degradation as a function of overlap depth when using sub-block processing in the decoding of turbo codes”, international mobile satellite conference (imsc’99), ottawa, canada, june 16-18, 1999. [8] div 1995, d. divsalar and f. pollara, “multiple turbo codes for deep-space communications”, jpl, tda progress report 42-121, may 15, 1995. [9] ben 1996, s. benedetto and g. montorsi, “unveiling turbo codes: some results on parallel concatenated coding schemes”, ieee trans. on inform. theory, vol. 42, no. 2, pp.409-428, march 1996. [10] ben 1997, s. benedetto and g. montorsi, “tutorial 11: turbo codes: comprehension, performance analysis, design, iterative decoding”, ieee international conference on communications (icc’97), montreal, quebec, canada, june 8-12, 1997. [11] bar 1994, a. barbulescu and s. pietrobon, “interleaver design for turbo codes”, electronics letters, vol. 30, no. 25, pp.210708, december 8, 1994. [12] ho 1998, m. ho, s. pietrobon, and t. giles, “interleavers for punctured turbo codes”, ieee asia-pacific conf. on commun. (apcc’98) and singapore int. conf. on commun. systems, vol. 2, pp. 520-524, singapore, november, 1998. [13] pit 1998, s. pietrobon, “interleaver address generator”, version 1.01, october 4, 1998, available from small world communications. see www.sworld.com.au. [14] sau 1998, p.-p. sauvé, "multibit decoding of turbo codes," master's thesis, university of toronto, canada, october 1998. [15] gui 1994, p. guinand and j. lodge, “trellis termination for turbo encoders”, proc. 17th biennial symp. on communications, queen’s university, kingston, canada, pp. 389-392, may 30-june 1, 1994. http://www.sworld.com.au/ ahmed s. hadi /al-khwarizmi engineering journal ,vol.2, no. 2 pp 1-14 (2006) 9 . fig. 2. illustration of the golden section principle. fig. 3. minimum distance between points versus number of points with a golden increment. fig. 1. turbo-code encoder using two rate 1/2 rsc codes with puncturing. ahmed s. hadi /al-khwarizmi engineering journal ,vol.2, no. 2 pp 1-14 (2006) 11 fig. 4. minimum difference between interleaved indexes versus number of bits considered with a golden relative prime interleaver. l_info=1028, t=393, area under curve=4620. fig. 5. minimum difference between interleaved indexes versus number of bits considered with a golden interleaver. l_info=1028, m=2, j=0, r=1, area under curve=5250. ahmed s. hadi /al-khwarizmi engineering journal ,vol.2, no. 2 pp 1-14 (2006) 11 fig. 6. per performance for rate 1/2 codes and a dithered golden interleaver with l_info=1028, m=1, j=0, r=1, and d=0.02. results are shown for no-termination (number of flush bits f=0), single-termination (f=4), and dual-termination (f=8). fig. 7. ber performance for rate 1/2 codes and a dithered golden interleaver with l_info=1028,m=1, j=0, r=1, and d=0.02. results are shown for no-termination (number of flush bits f=0), single-termination (f=4), and dual-termination (f=8). ahmed s. hadi /al-khwarizmi engineering journal ,vol.2, no. 2 pp 1-14 (2006) 12 fig. 9. ber performance for rate 1/3 codes with dual-termination and l_info=1028. the interleavers used are the “random” interleaver, the relative “prime” interleaver ( t=393), the “spread” interleaver (s=18), and the dithered “golden” interleaver (m=1, j=0, r=1, and d=0.02). fig. 8.per performance for rate 1/3 codes with dual-termination and l_info=1028. the interleavers used are the “random” interleaver, the relative “prime” interleaver ( p=393), the “spread” interleaver (s=18), and the dithered “golden” interleaver (m=1, j=0, r=1, and d=0.02). ahmed s. hadi /al-khwarizmi engineering journal ,vol.2, no. 2 pp 1-14 (2006) 13 fig. 10.per performance for rate 4/5 codes with dual-termination and l_info=1028. the interleavers used are the “random” interleaver, the relative “prime” interleaver ( t=393), the “spread” interleaver (s=18), and the dithered “golden” interleaver (m=1, j=9, r=15, and d=0.005). fig. 11 ber performance for rate 4/5 codes with dual-termination and l_info=1028. the interleavers used are the “random” interleaver, the relative “prime” interleaver ( t=393), the “spread” interleaver (s=18), and the dithered “golden” interleaver (m=1, j=9, r=15, and d=0.005). ahmed s. hadi /al-khwarizmi engineering journal ,vol.2, no. 2 pp 1-14 (2006) 14 سرعة مع بعض المفرقات المقترحةأداء الجفرة الم حمد ستار هاديأ واالتصاالت قسم هندسة المعلومات جامعة بغداد/ كلية هندسة الخوارزمي :الخالصة الجدرففدة المسفتردة عاففق المقذففع الففاذب interleaved)تصف ذففال المرةففدرة عففدد مفي اسففتراترجرات التفررفف ( golden( دالفاذب golden relative interleaverاذب المفرقفات الجدرفدة تفدعق البفارن الرسفب الف ( . الذررقتفاي الااررفة دالاالافة تت فمي قفرق حقرقرفة مرتبفة مةفتقة مفي dithered goldenدالمرتبف الفاذب ( أر ا سفرخخا بررفر االعتبفار . spreadالمقذع الاذب . المفر العةدائ الاي عادة رسمق مفر االرتةار المففر المرتبف رنفدي ادال .ج اداء الجفرة المسرعة سد تبري دتقاري مع عدد مي اسفتراترجرات التفررف رتائ ( القارفة دحجفق النتافة النبرفر . المففر code rateاالف ل رمداجرا دبصفدرة خاصفة فف حالفة رسفبة الجففرة الرفة . ذفال المفرقفات لخفا خصفائ ( الع puncture البارن الرسب الاذب رندي اداة مدذش فف رسفا الاقفا ارتةار مفردة دمستخدمة ف عدة تذبرقات غرر الجفرات المسرعة. dr. bassim s. mohammed al-khwarizmi engineering journal, 4, 2, (2008) 51-58 1 al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 10, no. 1, p.p.8391 (2014) the mutual interaction effects between array antenna parameters and receiving signals bandwidth bassim s. mohammed* emad s. ahmed** shahad d. sateaa*** *,**,*** department of electrical engineering / university of technology *email: bassim_sayed@yahoo.com **email: dr_emad_sa@uotechnology.edu.iq ***email: shahad4comm@yahoo.com (received 5 september 2013; accepted 31 march 2014) abstract the presence of a single complex adaptive weight in each element channel of an adaptive array antenna is sufficient for processing of narrowband signals. the ability of an adaptive array antenna to null interference deteriorates rapidly as the interference bandwidth increases. the performance of narrowband adaptive array antenna with lmcv beamforming algorithm is examined. the interaction effects between received signal angle of arrival and array parameters like the interelement spacing and the number of array element and the received signal bandwidth were studied. the output signal to interference plus noise ratio (sinr) and interference to noise ratio (inr) are used as performance parameters for evaluation of these effects. it is found that the amount of degradation in the output sinr is increased significantly with the increase of array interelement spacing, number of array elements and when the angle of arrival of received signals are closet to end fire. keywords: array parameters, recived signal bandwidth, narrowband adaptive array antenna. 1. introduction adaptive array antennas are playing an important role in many applications such as radar and communication system. adaptive processor can perform filtering in both space and frequency domain. by adjusting the amplitude and phase of the wavefront in each sensor, it is possible to electronically steer the main beam towards the look direction (desired signal), while suppressing any undesired signal [13]. the function of any adaptive array is to minimize the received power from one or more interference sources. the ability of the adaptive array antenna system to perform this function depends on many factors, some of which include the number of adaptive array elements, antenna aperture size, nulling bandwidth, number of interference sources, strength of signals, and spatial distribution of these sources [4]. in general, adaptive antenna array system is composed from m-element and adaptive processor as shown in fig (1). each sensor is followed by complex weight. this weight is calculated according to applied algorithm. the received signal vector x is multiplied by weight vector w and then summed to perform the output y(t). adaptive processor subdivided into two ports, the signal processing and adaptive algorithm [5, 6]. the processer hold the information of received signal and processed them according to the operating algorithm to produce the optimum weights which optimize the performance of the adaptive system. array antenna field pattern depends on the phase delay between array elements due to interelement spacing calculating on the operating frequency , so the wide mailto:bassim_sayed@yahoo.com mailto:dr_emad_sa@uotechnology.edu.iq mailto:shahad4comm@yahoo.com bassim s. mohammed al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 8391 (2014) 84 bandwidth signals will cause a sever distortion on the final field pattern due to the phase. the amount of degradation in the adaptive array performance due to signal bandwidth does not generate a high attention from researchers, in this paper we will try to investigate interaction effects between array parameters and receiving signal bandwidth. in section ii, we formulate the equations needed to calculate the received signal covariance matrix for an array with m elements. in section iii, the lcmv beamformer is briefly reviewed to calculated output sinr and inr. section iv, contains our simulations and results cases. finally, section v contains conclusions . fig. 1. m-elements adaptive array system. 2. mathematical formulation m-isotropic linear array antenna elements are considered to be uniformly distributed with inter element spacing (d) at the carrier frequency . the received signal by j th element can be written as … (1) equation (1) in a vector form is … (2) where are vectors of dimension for desired, interference and thermal noise, respectively. if the desired signal is incident from angle , then the desired signal vector is … (3) where m=1, 2, …, m and is desired signal spatial propagation delay between element … (4) if the interference signal is incident from angle , then the interference signal vector is … (5) where is the interference signal spatial propagation delay between element … (6) the thermal noise voltage of the j th array element is a random signal with zero mean and variance. the thermal noise components of channels are considered to be statistically independent. the output signal of array can be written as … (7) in vector form eq. (7) is … (8) where the weight vector (w) and the received signal vector (x) are vectors dimension and given by … (9) bassim s. mohammed al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 8391 (2014) 85 … (10) the covariance matrix of a received signal vector is defined as … (11) where “e” is the expected value of random variable since x (t) is a deterministic signal it has zero mean and it is considered as a stationary process, these assumptions leads to … (12) where is autocorrelation matrix of received signals vector x(t). the arriving signal has a flat power spectral density with amplitude over a bandwidth centered at frequency as shown in fig(2), then the fourier inverse of this signal is [7] … (13) for single array element the auto correlation function is …(14) where is signal relative bandwidth … (15) fig. 2. the power spectral density of received signal. the autocorrelation matrix of all received signal is hermitian (i.e. ) expressed as … (16) where are desired, interference and thermal noise autocorrelation matrix respectively. the correlation matrix of desired signal is … (17) where m=n=1, 2, …, m and are the matrix inverse of covariance matrix . substituting eq.(14) into eq. (17) gives …(18) where is the power of desired signal and is the desired signal relative bandwidth. …(19) where is interelement phase shift due to desired signal … (20) the correlation matrix of interference signal is found to be … (21) substituting eq.(14) into eq. (21) gives …(22) where is the power of interference signal and is the interference signal relative bandwidth. …(23) where is interelement phase shift due to interference signal … (24) the correlation matrix of noise components are independent and equal to … (25) where is the variance of thermal noise components. bassim s. mohammed al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 8391 (2014) 86 3. lcmv beamforming the basic idea behind the linearly constrained minimum variance (lcmv) beamforming is to constrain the response of the beamformer, so signals from the direction of interest are passed with specified gain and phase. the weights are chosen to minimize output variance or power subject to the response constraint. this has the effect of preserving the desired signal while minimizing contributions to the output due to interfering signals and noise arriving from directions other than the direction of interest [8, 9]. subject to …(26) where is the autocorrelation matrix ( ), c is a constraint matrix for look direction (desired direction). … (27) the optimum steady state weight vector [ can be accomplished by method of lagrange multipliers … (28) with the optimum weight vector given in eq. (28), the output powers due to desired, interference and noise are given by … (29) … (30) … (31) then the output sinr is given by …(32) and the output inr is given by …(33) 4. simulation and results the simulation cases programes are written by matlab 8.2 and the following assumptions are considered  isotropic linear array antenn uniformaly distribution.  desired signal input power is 0db and interference input power is 20db.  interference sourece angle of arrival is from endfire ( ). case 1 ten isotripoic array elements with 0.5 inter element spacing is considered. a desired signal angles of arrival are assumed to be from ( ). fig (3) shows that the output sinr is degraded with the increase of interference bandwidth for all desired signal angles of arrival.the degradation is increased when the desired signal angle of arrival moves towards end fire (decreased), this is due to the increase in element phase delay ( ) and this in turn leads to an increase in the interference relative bandwidth as given in eq.(23). fig. (4) shows that the output inr is increased when the interference bandwidth is increased which means more interference power will appear at the output of the system due to limation of narrowband array processor. bassim s. mohammed al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 8391 (2014) 87 fig. 3. output sinr plot versus interference relative bandwidth for different desired signals angle of arrival. fig. 4. output inr plot versus interference relative bandwidth for different desired signals angle of arrival. case 2 ten isotripoic array elements with desired signal angle of arrival from and for different interelment spacings (d= 0.25, 0.5, 0.75 ). fig. (5) shows that the output sinr is degraded when the interference bandwidth is increase for all inter element spacing (d= 0.25, 0.5 and 0.75 ). the increase in the interelement spacing from 0.25 to 0.75 cause an increase in the effect of interference relative bandwidth as given in eq.(23), so it causes a more degradation in the outpt sinr. fig. (6) shows that the output inr is increased with the increase in the interferences bandwidth and interelment spacing this is due to the increase in the effect of interference bandwidth effect on a narrowband processor. 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 1 2 3 4 5 6 7 8 9 10 interference relative bandwidth s in r ( db ) desired angle of arrival =80° desired angle of arrival =60° desired angle of arrival =40° 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 -10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 interference relative bandwidth in r (d b ) desired angle of arrival =80° desired angle of arrival =60° desired angle of arrival =40° bassim s. mohammed al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 8391 (2014) 88 fig. 5. sinr plot versus interference relative bandwidth for different interelements spacing fig. 6. inr plot versus interference relative bandwidth for different interelements spacing case 3 two array sets with nine and four elements with 0.5 inter element spacing are considered. a desired signal angle of arrival is from with relative bandwidth between 0 to 0.5. fig. (7) shows that the system exhibit more degradation in the output sinr when the number of array antenna is increased from 4 to 9 (i.e. when the array system has wide operatere). this is due to the increase in the effect of interference bandwidth with the increase of array aperture (array aperture = number of element interelement spacing) according to eq. (23). it can be also shown that when interference relative bandwidth is (0.3), the amount of drop in the output sinr is (3.504db) for four elements and (3.608) for nine elements. figure (8) shows the same reasons mentioned above that the output inr is higher for the case of nine element due to increase in the array aperture. 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 1 2 3 4 5 6 7 8 9 10 interference relative bandwidth s in r ( d b ) d= 0.25 lamda d= 0.5 lamda d= 0.75 lamda 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 -10 -9 -8 -7 -6 -5 -4 -3 -2 -1 interference relative bandwidth in r (d b ) d= 0.25 lamda d= 0.5 lamda d= 0.75 lamda bassim s. mohammed al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 8391 (2014) 89 fig. 7. sinr plot versus interference relative bandwidth for different number of antennas. fig. 8. inr plot versus interference relative bandwidth for different number of antennas. 5. conclusion it is found from the presented result in this paper there is a significant mutual effect between array parameters and receiving signal bandwidth. theses mutual effects can be defend as follows generally the performance of adaptive array system with narrowband processor is degraded with the increase of received signal bandwidth. the degree of degradation is depending on the array parameters as well as on the value of received signal bandwidth. the increase in the number of array element causes an increase in the array aperture which makes the array antenna sensitive to the bandwidth of received signal, wide aperture cause more degradation in the output sinr. the received signal angle of arrival plays a role on the amount of bandwidth performance that the narrowband signal can be peer. it is found that the received signal is at the broadside angle the system is more sensitive for the received signal band width. the increase in the interelement spacing cause an in increase in the aperture of antenna which makes the effects of the received signal bandwidth more significant. 6. references [1] nordin bin ramli, “study on subband adaptive array for space-time codes in 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 1 2 3 4 5 6 7 8 9 10 x: 0.3 y: 3.608 interference relative bandwidth si n r (d b ) x: 0.3 y: 3.504 m=9 m=4 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 -10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 x: 0.3 y: -3.352 interference relative bandwidth in r (d b ) x: 0.3 y: -2.95 m=9 m=4 bassim s. mohammed al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 8391 (2014) 90 wideband channel”, ph. d thesis, university of electro-communications, march, 2008. [2] b. widrow, p. e. mantey, l. j. gri_ths, and b. b. goode, “adaptive antenna systems”, proceeding of the ieee, vol. 55, no. 12, pp. 2143-2159, december, 1967. [3] n. kikuma, adaptive antenna technology (in japanese), ohmsha, ltd., oct. 2003. [4] alan j. fenn, “adaptive antennas and phased arrays for radar and communications”, massachusetts institute of technology, lincoln laboratory, 2008. [5] robert a. monzingo, randy l. haupt and thomas w. miller, “introduction to adaptive arrays”, 2 nd edition, scitech publishing, 2011. [6] singh h. and jha r. m., “trends in adaptive array processing”, international journal of antennas and propagation, vol. 1, 2012. [7] r. t. compton, jr., “the bandwidth performance of a two-element adaptive array with tapped delay-line processing”, transactions on antennas and propagation ieee, vol. 36, no. 1, pp. 5-14, january, 1988. [8] v. k. madisetti, “the digital signal processing handbook”, 2 nd edition, 1999. [9] d. h. johnson and d. e. dudgeon, array signal processing: concepts and techniques, signal processing series. prentice hall, englewood cliffs, nj,1993. (2014) 8391، صفحة 1، العدد10دمجلة الخوارزمي الهندسية المجل باسم سعيد محمد 91 واستقبال إشارات النطاق الترددي معامالت مصفوفة الهوائياتآثار التفاعل المتبادل بين **عماد شهاب احمد * باسم سعيد محمد ***شهد ضاري ساطع الجامعة التكنولوجية/ قسم الهندسة الكهربائية ***،**،* bassim_sayed@yahoo.com :البريد االكتروني* dr_emad_sa@uotechnology.edu.iq :البريد االكتروني** shahad4comm@yahoo.com : البريد االكتروني *** الخالصة أن قابلية .ةالضيق ذات الحزمة الترددية شاراتاإل لمعالجة تكفي فقط تكيفيةمالمصفوفة العنصر من عناصرفي كل مصفوفة توازن معقدة واحدة وجودان تم (. (lmcvمع خوارزمية للحزمة الضيقة المتكيفةالهوائيات مصفوفة تم فحص اداء .النظام لتخميد التداخل ستسوء بزيادة الحزمة الترددية لمصدر التداخل و (sinr) معامالت قياس الجودةتم استخدام .اصرمعامالت مصفوفة الهوائيات وتأثيرات عرض الحزم لإلشارات المستلمةات المتباينة بين عنتأثيرالدراسة (inr) لقد توصل البحث الى أن مقدار التدهور في . في تقيم هذه التاثيرات على عمل المنظومة(sinr) بصورة ملحوظة بزيادة عدد الهوائيات زداد ي .end fireوالمساحة الفاصلة بين الهوائيات وكذلك عندما تكون زاوية الوصل لإلشارة المستلمة قريبة من mailto:bassim_sayed@yahoo.com mailto:dr_emad_sa@uotechnology.edu.iq mailto:shahad4comm@yahoo.com (microsoft word 8 91\343\355\313\343 \346\321\307\310\315\3111) al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 14, no. 3, september, (2018) p.p. 8191 recovery of aluminum from industrial waste (slag) by melting and electrorefining processes maytham mahmood ali* rabiha saleh yassen** *,**department of production and metallurgy engineering/ university of technology m@yahoo.coaythamaltamarm :email* rabihazw@yahoo.comemail: ** (received 23 august 201 7; accepted 18 march 2018) https://doi.org/10.22153/kej.2018.03.002 abstract slag of aluminum is a residue which results during the melting process of primary and secondary aluminum production. salt slag of aluminum is hazardous solid waste according to the european catalogue for hazardous wastes. hence, recovery of aluminum not only saves the environment, but also has advantages of financial and economic returns. in this research, aluminum was recovered and purified from the industrial wastes generated as waste from both of state company for electrical and electronic industries (baghdad/alwaziriya) and general company for mechanical industries (babylon/-al-escandria). it was found that these wastes contain tiny proportions of other elements such as iron, copper, nickel, titanium, lead, and potassium. wastes were recovered for green sustainability, saving energy and cost effectiveness. the method applied for recovering aluminum was pyro-metallurgical method by smelting and refining. x-ray fluorescence spectroscopy and xray diffraction techniques of the slag sample were used to determine the chemical analysis and phases, respectively. melting experiments were conducted by using different types of fluxes (kalf4, nacl, kcl and alcl3) at different percentages (0, 5, 10 %) and different melting temperatures (700, 750, 800oc). design of experiment (doe) by taguchi method, orthogonal array l9, was used in melting experiments. melting efficiency of aluminum was equal to 84.7%. electro-refining of aluminum was done by using anhydrous aluminum chloride and nacl as ionic liquids at low temperature 100 ◦c in electro-refining method producing aluminum of 99% purity. keywords: design of experiment (doe), electro-refining, melting process, %recovery, salt slag of aluminum. 1. introduction aluminum is the most abundant element after the oxygen and silicon in the earth’s crust (by weight). it is never been as a free metal in nature and constitutes approximately 8% of the solid earth surface. aluminum (al) is one of the most important metals, since its industrial production, demand for aluminum has been continuously increasing to around 53 million tons in 2014 and its application has expanded to variety of economic sectors. aluminum contains a combination of important properties that makes it a metal used in many fields, in the medical, military, aerospace, marine, and several household uses [1]. there are three ways for extracting aluminum, primary source from aluminum ores (bauxite ore), secondary source from aluminum scrap and white dross, tertiary source from black dross and salt slag. extraction of aluminum starts with bauxite mining, bauxite is processed into alumina, and then alumina is processed into aluminum metal. extraction of aluminum involves mining of bauxite (open pit), and alumina is produced by bayer process. secondary aluminum production is by electrolytic smelting by hall heroult technique [2]. recycling aluminium is also known as secondary aluminum. all aluminum products can be recycled after use. recovering of aluminum is very important because of several environmental and economic maytham mahmood ali al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 8191 (2018) 82 reasons. comparison with extraction of aluminum, recycling of aluminum products needs as little as 5% of the energy, and emits only 5% of the greenhouse gas. recycling of aluminum has environmental amelioration and economical advantage. in the production of aluminum as shown in (table 1) there is a significant difference in energy between aluminum extraction and recycling compared with other metals; 186 mj/kg for primary compared to 10-20 mj/kg for secondary [3]. about 50% of scrap is old scrap (scrap from end of life products eol). recycling is fully dependent on scrap as an important source in the aluminum industry, such as used cans, foils, extrusions, commercial scraps, turnings, and old rolled or cast metal. aluminum can also be recovered from skimming, dross and slag [4]. table1, comparison of primary and secondary aluminum smelting processes (data from gil 2005). secondary smelting primary smelting parameters 10 12 400 1.6 174 204 2,100 to 3,650 57 consumption of energy(gj/t al produced) atmospheric emissions (kg/t al produced) solid waste (kg/t al produced) consumption of water (kg/t al produced) the main general categories of operations included in the secondary aluminum production are scrap pretreatment, smelting and refining. pretreatment operations of scrap involve sorting, processing, and cleaning scrap. smelting and refining operations involve “cleaning, melting, refining, alloying, and pouring of aluminum recovered from scrap”. some steps may be combined or reordered, depending on the quality of scrap, scrap sources, design of the furnace, availability of auxiliary equipment and product specifications. factory configuration, the type of scrap usage, and the output product vary over the secondary aluminum industry. during melting process for aluminum scrap, a layer of oxide is formed on the surface of the molten in large quantities, and the oxide layer must be removed from the molten product for a high quality finished product. in order to avoid the formation of more oxidation phases and enhance an easier separation during smelting, the flux must be used to protect the molten. the flux works on docking with the impurities to be removed from the molten and separating the metal from the impurities as oxide. the molten surface layer is made of oxides, gases, fluxes and some metals with a quantity of metal additive. its common name is aluminum slag [5]. a large number of experiments and studies indicate that the bulk of undesirable metals is a real and increasing problem, at every metal recycling processes, p. e. tsakiridis, et al.(2012) studied a process for the recovery of aluminum by treating black dross of aluminum , a waste formed during aluminum scrap smelting [6]. li jinping et al. (2007) investigated the recovery of aluminum and iron from boiler slag taken from factories using coal. recovery of aluminum based on the applications of hydro-metallurgical processes, like leaching, precipitation, solvent extraction, crystallization and re-crystallization and using sulfuric acid (h2so4) as a leachant for recovery of aluminum [7]. mikito ueda et al. (2005) studied a process for recovering of aluminum from aluminum dross by a floating separation of al from oxides and then electrolysis of oxides implemented in molten salt bath of 51 mol % naf, 33 mol% alf3, and 16 mol% bacl2 at 1073k, by the flotation separation [8]. in status of aluminum, the schedule of problematic impurities is very large, involving but not limited to fe, si, cu, mg, ni, zn, pb, cr, mn and v [9]. the production of secondary al annually generates worldwide a considerable amount of slag (more than 3.5 million tons dross and salt slag), which presents the variability of chemical and mineralogical composition. generally, the al slag is a mixture of al oxide, metals, chloride, fluoride, alloying elements and salts from the fluxing agent, nitride, carbide, sulfides, and other substances, which are the result of molten al reactions with other elements present in the melting system. in contact with rain water, they can react emanating inflammable or toxic gases, such as methane and ammonia, or may become soluble, infiltrating the soil and finally reaching the groundwater; therefore, they are considered dangerous for the environment [10]. the main purpose of this project is to understand the fundamental knowledge of recovery of aluminum from industrial waste in iraq and the limitation of recovery. the aims and scope of the study are summarized by the following: (1) this research was designed to explain the different parameters affecting on recovery of aluminum from industrial waste (slag) using melting technique. (2) recovery of aluminum from the industrial waste (slag) by collecting the slag and then crushing, smelting and refining to obtain aluminum with high purity. (3) investigating the effect of major factors that may affect the efficiency of melting, maytham mahmood ali al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 8191 (2018) 83 such as temperature, types of fluxes, stirring and using inert gas (argon). 2. experimental work to prepare data-base of characterization of waste produced in iraqi general companies, samples of slag have been taken from different regions in iraq and then tested. the slag sample used in this work is from general company for electrical and electronic industries (baghdad-al waziriya) and general company for mechanical industries (babel-alescandria). the chemical composition of slag’s sample is shown in table 2. the chemical analysis was conducted in the ministry of science and technology. the used tests involved chemical composition, microstructure, xrf and scanning electron microscope. effect of additives of the flux has been studied with different fluxes and different percentages of fluxes through melting process. in order to study the effect of re-melting recovering parameters on the salt slag of aluminum, the designs of experiment and optimization should be performed. this study is designed to determine the important parameters and the method of characterizations. the different techniques used to evaluate the object of study are also explained. the process planning is summarized in figure 1. table 2, chemical composition of slag’s sample, wt% al v pb ti zn ni cr mn cu fe si bal 0.0010 1.213 0.0005 17.82 0.848 1.192 4.50 24.09 24.85 4.494 fig. 1. flow diagram of beneficiation technique. maytham mahmood ali al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 8191 (2018) 84 2.1. fluxing and degassing of aluminum in aluminum (al) smelting and especially in the re-melting of industrial waste, such as slag, a large amount of oxide and nonmetallic impurities formation is common. in order to prevent the oxidation and removal of impurities, multi types of fluxes such as kalf4 (foseco, staffordshire england b783tl), which was obtained from the general company electrical and electronic industries, were used. also, other types of fluxes, such as (nacl, kcl and alcl3) were utilized with the use of inert gas (argon). 2.2. preparation of slag the slag sample of 15 kg received from general company electrical and electronic industries and general company for mechanical industries was crushed by laboratory jaw crusher. slag particles size at the end of operation was (1-3 mm) and then slag was mixed in a mechanical mixer. 2.3 melting procedure after crushing and mixing, the smelting process of slag is carried out. 100 gm of slag samples are weighed on a sensitive balance, then placed in a crucible made of alumina and then placed in the electrical furnace. the slag was melted at different temperatures (700 750 800oc) under inert gas (argon) to prevent the oxidation that occurs during the melting process, then removing the slag that formed at the top of the molten and then pouring the molten in the mold. the mold used in this process was carbon steel and it was heated to 300oc before pouring the melt into the mold. smelting process product was conducted at different temperatures (700-750800oc) using fluxes (kalf4 nacl , kcl alcl3) with different quantities and using inert gas (argon ) and stirring process for the molten. the molten was poured again into the mold and then tested in xrf. the efficiency of melting process was determined using two terms, namely % recovery and % yield. where: % recovery = m2/m1 … (1) % yield = m2/m1+m3 … (2) where: m1: weight of the slag before melting. m2: weight of the sample after melting. m3: weight of the flux. 2.4 electro-refining of impure aluminum at low temperature in the electro-refining process, the impure aluminum alloy is used as the anode and it is electro-refined in an ionic liquid prepared from anhydrous alcl3 and nacl. electro-refining methods at low temperature (100 ◦c) produce aluminum with 99% purity. electrolysis at low temperature can provide significant energy savings. for this purpose, anhydrous alcl3 and nacl are the ionic liquid. the non-pure aluminum is placed as an anode and a solution of (anhydrous alcl3-nacl). the cathode is either pure aluminum or pure copper. this electrolysis is capable of removing mn, fe, si, cu, zn, ni, and pb. the solution can be reused more than once, thus making the process more environmentally friendly. this is because the ionic solution is stable at low temperatures. aluminum deposited on the cathode can be seen by light optical microscopy and scanning electron microscope (sem). 2.5 process variables and design of experiment (doe) operation variables of temperature, weight of kalf4 flux, weight of nacl, kcl flux and weight of alcl3 flux were chosen as main four control factors with their identical three levels to be investigated. table 3 shows the investigated four controlled factors and their three corresponding levels. table 3, controlled factors and their corresponding levels correspondence levels controlled factors level 3 level 2 level 1 10 5 0 4weight of kalf flux, wt% 10 5 0 weight of nacl, kcl flux, wt% 10 5 0 3weight of alcl flux, wt% 800 750 700 melting cotemperature, nine experiments were selected according to taguchi method (orthogonal array) (table 4). using the taguchi rules with three levels and four processing variables, the nine experiments using l9 array is described in (table 5). table 6 represents all nine experiments with their levels. maytham mahmood ali al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 8191 (2018) 85 two trials were made for each experiment to get the average data. table 4 taguchi orthogonal array [11] table 5, taguchi orthogonal array for melting process l9 controlled factor 4 controlled factor 3 controlled factor 2 controlled factor 1 experiments 1 1 1 1 1 2 2 2 1 2 3 3 3 1 3 3 2 1 2 4 1 3 2 2 5 2 1 3 2 6 2 3 1 3 7 3 1 2 3 8 1 2 3 3 9 table 6, the experiments used in the melting process c)omelting temperature,( 3weight alcl flux weight nacl,kcl flux flux 4weight kalf experiments 700 0 0 0 1 750 5 5 0 2 800 10 10 0 3 800 5 0 5 4 700 10 5 5 5 750 0 10 5 6 750 10 0 10 7 800 0 5 10 8 700 5 10 10 9 3. results and discussion the results obtained from the melting processes of slag by melting it in electrical furnace with different temperatures (700,750, 800oc), using different types of fluxes (kalf4, nacl, kcl, alcl3), using inert gas, stirring to recover the aluminum alloys, and design of melting experiments by taguchi method depending on the controlled factors. maytham mahmood ali al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 8191 (2018) 86 table 7, values and average of melting percentage of aluminum with and without using flux at different temperature at (toa) l9. average melting al wt% melting 2 al wt% melting 1 al wt% melting temperature, oc weight alcl3 flux weight nacl,kcl flux weight kalf4 flux exp. 83.7055 83.8 83.611 700 0 0 0 1 84.1950 84 84.39 750 5 5 0 2 84.3350 84.1 84.57 800 10 10 0 3 84.6950 84.73 84.66 800 5 0 5 4 85.0000 84.9 85.1 700 10 5 5 5 83.9500 83.8 84.1 750 0 10 5 6 84.5200 84.7 84.34 750 10 0 10 7 83.900 83.6 84.2 800 0 5 10 8 88.8350 88.97 88.7 700 5 10 10 9 mean weight for all experiments is 84.7 table 8, best optimal levels values of controlled factors for the aluminum melting with using fluxes , inert gas (argon) and stirring. factors value level weight kalf4 flux 10 3 weight nacl,kcl flux 10 3 weight alcl3 flux 5 2 temperature (oc) 700 1 fig. 2. melting efficiency of aluminum by using defferent types of fluxes and different temperatures for each level of the controlled factors. 3.1. signal-to-noise (s/n) ratio at parameters design, the factors were divided into two kinds: control factors which can be easily controlled by the experimenters and noise factors which can be difficult or expensive to control during operation. to determine (s/n) ratio, there are three types of formulations. in this study, the second formula is used which represents the larger signal to noise ratio, giving the best melting efficiency [12-13]. 1lower is the better � � = -10 log(� ��� � � �� …(3) 2higher is the better � � = -10 log(� ���� � �� …(4) 3nominal is the better � � = 10 log(� ��� �� � �� …(5) maytham mahmood ali al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 8191 (2018) 87 table 9, values of s/n ratio for melting aluminum by using different fluxes and different temperatures. s/n ratio melting 2 al wt% melting 1 al wt% melting temperature, oc weight alcl3 flux weight nacl, kcl flux weight kalf4 flux exp. 38.4551 83.8 83.611 700 0 0 0 1 38.5057 84 84.39 750 5 5 0 2 38.5201 84.1 84.57 800 10 10 0 3 38.5572 84.73 84.66 800 5 0 5 4 38.5884 84.9 85.1 700 10 5 5 5 38.4804 83.8 84.1 750 0 10 5 6 38.5391 84.7 84.34 750 10 0 10 7 38.4751 83.6 84.2 800 0 5 10 8 38.9717 88.97 88.7 700 5 10 10 9 mean of sn ratio for all experiments is 38.55 3.2. analyses of variances (anova) this analysis method is used to determine the importance of any processing variable on the overall of the process concern (table 10). the general terms described are in % importance [14]. + .temp +ss(alcl3) +sskcl ), ( nacl ss+)kalf4( =ss tss )6( … error ss ��� = � ��� − �� � � � … (7) ��� = ∑ ����� � − �� � ... (8) where: is total sums of squares parameters and error. tss g is sum of the results data for all the experiments. n is total number for all the experiments. � is level number. c is one of the tested parameters. ∑ �� is sum of results for all experiments; i.e, at parameter c and at level �, and � is number of parameters. degree of freedom was calculated by the following equation: )9( … 1-=ccdof )10( … 1-=ttdof where; c represents the levels for each parameter (controlled factor), and t represents the number of experiments. also, contribution percentage (%ρ) was calculated for each controlled factor and for the error from the following equation �% = ��� ��� ... (11) when: factors are chosen controlled≤ 15%, so the errorρ not active. chosen controlled factors are the ≥ 50%, so errorρ active. table10 summarizes anova data obtained from equations. the table shows the contribution of each controlled factor on the melting efficiency of aluminum from slag. ...................... ........................... ................. table 10, anova for melting aluminum from slag for each controlled factors. % contribution (%ρ) sum of squares (s) degree of freedom (dof) factors 18.407 0.037 2 weight kalf4 flux 18.407 0.037 2 weight nacl, kcl flux 28.358 0.057 2 weight alcl3 flux 23.382 0.047 2 temperature oc 11.442 0.023 0 error 100% 0.201 8 total 3.3. electro-refining of aluminum at low temperature electro-refining methods are shown in figure 3 for produced aluminum of 99% purity at 1.5 volt and low temperature about 100oc by using anhydrous aluminum chloride alcl3 and nacl. maytham mahmood ali al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 8191 (2018) 88 fig.13. scanning electron microscope (sem) images of deposited aluminum produced by electrorefining process. 3.4. discussion of melting process melting process was effective for recovering aluminum from the industrial waste, so using different fluxes, different temperatures, and using inert gas (argon) and stirring the melt were the alternative for aluminum recovery. 3.4.1. effect of adding kalf4 flux the effect of adding kalf4 flux on the melting of aluminum slag was studied, and the ratio of adding kalf4 flux is in the range of (0 10). the results represented in fig.2 show that the increase in amount of kalf4 at the melting process leads to increase the melting efficiency of aluminum. the role of kalf4 flux is to separate metals from slag and oxide and to prevent agitating burning of the aluminum during melting process, and therefore maximizing yields. when kalf4 is added to a mixture of nacl and kcl, the fluidity of the flux increased. this increasing fluidity better covers the exposed molten metal and facilitates the release of metals entrapped in the slag. the active fluoride will also remove magnesium (mg) in the melt and improve the metal purity. it is possible to conclude that the fluoride additions decrease the viscosity of the molten salt and cause an increase in aluminum recovery as the amount of fluoride increases in the molten salt [15]. the best result in adding kalf4 flux was done at 10 wt% with using inert gas during melting process and stirring the molten metal. at fluoride concentrations 10 wt%, the drop in fluxaluminum interfacial tension was roughly. but generally, the salts especially those containing fluorides can destroy and remove the strong and dense oxide skins from the molten aluminum alloys, which can then freely coalesce. though, that can be provided up to 10% oxide concentrations, at higher concentrations some forms of mechanical agitation are also required because the coalescence is extremely impaired due to the viscosity changes [16]. table 10 shows the % contribution (%ρ) of kalf4. flux is (18.407) on the melting process of aluminum from salt slag. 3.4.2. effect of adding nacl, kcl flux it can be seen clearly from fig.2 the effect of adding nacl, kcl fluxes on the melting process, the ratio of adding nacl, kcl fluxes is in the range of (0 10). the results represented in figure 2 show the increasing in amount of nacl, kcl fluxes at melting process leads to increase the melting efficiency of aluminum. (nacl, kcl) fluxes added to separate the surface attached to impurities, to enhance coagulation of drops of melt, and to protect the bath surface against oxidation. all the chloride salts formed are less dense than liquid aluminum, and will float and accumulate at the dross layer on top of the melt [17]. figure 2 also shows that the best result is at 10 wt% of nacl, kcl flux, and the addition was done with using inert gas (argon) and stirring the molten metal. table 10 shows the % contribution (%ρ) of nacl, kcl flux is (18.407) on the melting process of aluminum from salt slag. .............................................. maytham mahmood ali al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 8191 (2018) 89 3.4.3 effect of adding alcl3 flux the effect of adding alcl3 during melting process was investigated, and the ratio of addition is in the range of (0 10). the results represented in figure 2 and (table 7) for experiment no.9. shows the good result was at 5 wt% alcl3 with 10 wt% kalf4 flux and10 wt% nacl, kcl fluxes in melting process and table 10 shows alcl3 have the best %contribution (%ρ) is (28.3%) of each controlled factor on the melting of aluminum from slag. 3.4.4. effect of temperature the temperature effect on the melting of aluminum by using electric furnace was studied. the results showed that the temperature had a negative effect at 800oc on the melting of aluminum, as shown in fig.2 no satisfactory explanation is offered for the decrease in the length of the spirals resulting from superheating to 800°c. gas absorption by the molten aluminum during melting was suggested as a possible explanation of this phenomenon. at the present time, it is generally accepted that hydrogen is the gas most readily absorbed by molten aluminum. methods of removing hydrogen from molten aluminum or aluminum alloys with chlorine, chlorine mixed with nitrogen, or chlorine compounds have been studied by a number of investigators [18]. table 10 shows the % contribution (%ρ) of temperature is (23.382) on the melting process of aluminum from salt slag. 4. conclusions in this work, the main following conclusions can be obtained: 1. melting technique of salt slag that obtained from general company for electrical and electronic industries (baghdad-al waziriya) and general company for mechanical industries (babel-alescandria) can be successfully applied. 2. the effect of fluxes (kalf4, nacl , kcl ) on the melting process was positive, and increasing the level of these three factors led to increase the melting efficiency of aluminum. 3. 3-the effect of alcl3 flux on the melting process was negative at 10 wt% but was good at 5 wt%, and increasing the level of this factor to 10wt% led to reduce the melting efficiency of aluminum. 4. the effect of high temperature above 800 oc on the melting process was negative, and increasing the temperature led to reduce the melting efficiency of aluminum. 5. aluminum with high purity was obtained; purity was 99% by electro-refining of impure aluminum by using anhydrous aluminum chloride and nacl as ionic liquids at low temperature (100oc). 6. the melting efficiency of aluminum was found 84.7 %. 5. references [1] c.s. schmitz, handbook of aluminum recycling, essen, germany, (vulkan verlag), (2006)27-30. [2] c. klauber, m. gräfe and g. power, bauxite residue issues: ii. options for residue utilization, hydrometallurgy, 108 (2011)1132. [3] john. a.s. green, aluminum recycling and processing for energy conservation and sustainability, materials park, ohio, united states of america, asm international, (2007). [4] [4] aluminum recycling, j. light met. 2 (2002)89-93. [5] d. a. pereiraa , barroso de aguiar , f. castro , m .f. almeida and j. a. labrincha, mechanical behaviour of portland cement mortars with incorporation of al-containing salt slags, cement and concrete research 30(2000)1131-1138. [6] p. e. tsakiridis, “aluminium salt slag characterization and utilization – a review”, journal of hazardous materials, 217218(2012) pp.1-10. [7] li jinping, hou haobo, gan jinhua, zhu shujing, xie yongjie, extraction of aluminum and iron from boiler slag by sulfuric acid, j. natural sciences,12(2007)541-547. [8] mikito ueda, shiro tsukamoto, shoichi konda, toshiaki ohtsuka, recovery of aluminum from oxide particles in aluminum dross using alf3-naf-bacl2 molten salt, journal of applied electrochemistry, 35(2005)925–930. [9] gabrielle gaustada and elsa olivetti and randolph kirchainb, improving aluminum recycling: a survey of sorting and impurity removal technologies, resources, conservation and recycling, 58(2012) 79-87. [10] romanita teodorescu, viorel badilita, maria roman and aurel crisan , optimization of process for total recovery of aluminum from maytham mahmood ali al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 8191 (2018) 90 smelting slag 2.removal of aluminum sulfate, environmental engineering and management journal, 13(2013)7-14. [11] d. mahaboob valli, t.k. jindal. application of taguchi method for optimization of physical parameters affecting the performance of pulse detonation engine. journal of basic and applied engineering research, 1(2014)18-23. [12] j.berube.becton dickinson, franklin lakes and c.f.j.wu., signal-to-noise ratio and related measures in parameter design optimization :an overview. sankhya: the indian of statistics, 62(2000)417-432. [13] görkem kökkülünk, adnan parlak, eyup bağci, zafer aydin. application of taguchi methods for the optimization of factors affecting engine performance and emission of exhaust gas recirculation in steaminjected diesel engines.acta polytechnica hungarica, 11(2014)95-106. [14] srinivas athreya, dr y.d.venkatesh. application of taguchi method for optimization of process parameters in improving the surface roughness of lathe facing operation. international refereed journal of engineering and science, 1(2012)13-19. [15] d. scott george, e. totten, handbook of aluminum, alloy production and materials manufacturing, marcel dekker, new york, 2(2003). [16] takehito hiraki, takahiro miki, kenichi nakajima and kazuyo matsubae , shinichiro nakamura and tetsuya nagasaka, thermodynamic analysis for the refining ability of salt flux for aluminum recycling, materials, (2014). [17] s.s. akbari, minimizing salt and metal losses in mg-recycling through salt optimization and black dross distillation, dissertation, shaker verlag, (2011). [18] a. i. krynitsky and c. m. saeger, jr., effect of melting conditions on the running quality of aluminum cast in sand molds, part of journal of research of the rational bureau of standards, vol.13. )2018( 81-91، صفحة 3د، العد14دجلة الخوارزمي الهندسية المجلمميثم محمود علي 91 الخبث) بواسطة عملية الصهر وعملية التنقية( استرجاع األلمنيوم من المخلفات الصناعية رابحة صالح ياسين** علي*ميثم محمود التكنولوجيةقسم هندسة االنتاج والمعادن / الجامعة ،*** maythamaltamar@yahoo.co:البريد االلكتروني* rabihazw@yahoo.com :البريد االلكتروني** ________________________________________________________________________________ الخالصة بة الخطرة حسب خبث األلومنيوم هو البقايا التي تنتج أثناء عملية الصهر إلنتاج األلمنيوم األولي والثانوي. يعتبر خبث األلومنيوم من المخلفات الصل فوائد اخرى من الناحية المالية واالقتصادية. هاألوروبي للنفايات الخطرة. وبالتالي، استرجاع األلومنيوم من الخبث ليس فقط لحماية البيئة، ولكن أيضا لالبيان عات الكهربائية وااللكترونية/ في هذا البحث تمت عملية استرجاع وتنقية األلمنيوم من المخلفات الصناعية الناتجة عن مخلفات صناعية للشركة العامة للصنا أخرى مثل الوزيرية ومخلفات الشركة العامة للصناعات الميكانيكية / اإلسكندرية. حيث تحتوي المخلفات باالضافة الى االلمنيوم على نسب من عناصر لى البيئة، وتوفير الطاقة والكلفة االقتصادية. وكانت الحديد، النحاس، النيكل، التيتانيوم، الرصاص، والبوتاسيوم. حيث يتم استرجاع االلمنيوم للمحافظة ع شعة السينية لعينة الطريقة المطبقة السترجاع األلمنيوم بالطريقة الحرارية عن طريق الصهر والتنقية. واستخدمت تقنيات التحليل الطيفي وتقنيات انعراج األ ) 4kalf, nacl , kcl , 3alclالصهر باستخدام أنواع مختلفة من مزيالت الخبث (التحليل الكيميائي ومعرفة االطوار. أجريت تجارب أيجاد الخبث في ، في l9). تم استخدام تصميم التجارب بطريقة تاغوتشي سيليزية ٨٠٠ ، ٧٥٠، ٧٠٠) ودرجات حرارة انصهار مختلفة (١٠، ٥، ٠و بنسب مختلفة ( و كلوريد يتمت عملية التحليل الكهربائي لأللمنيوم بأستخدام كلوريد األلومنيوم الالمائ٪. وقد 84.7 تجارب الصهر. وكانت كفاءة عملية صهر األلمنيوم ٪.٩٩سيليزية ، في طريقة التحليل الكهربائي تم الحصول على األلومنيوم بنقاوة ١٠٠سوائل أيونية عند درجة حرارة منخفضة كالصوديوم ________________________________________________________________________________ al-khwarizmi engineering!!! journal al-khwarizmi engineering journal, vol. 7, no. 2, pp 36 46 (2011) performance improvement of neural network based rls channel estimators in mimo-ofdm systems alaa abdulameer hassan department of mechatronics engineering/ al-khawarizmi college of engineering/ university of baghdad e-mail: alaa_ah76@yahoo.com (received 14 febrewary 2011; accepted 12 may 2011) abstract the objective of this study was tointroduce a recursive least squares (rls) parameter estimatorenhanced by using a neural network (nn) to facilitate the computing of a bit error rate (ber) (error reduction) during channels estimation of a multiple input-multiple output orthogonal frequency division multiplexing (mimo-ofdm) system over a rayleigh multipath fading channel.recursive least square is an efficient approach to neural network training:first, the neural network estimator learns to adapt to the channel variations then it estimates the channel frequency response. simulation results show that the proposed method has better performance compared to the conventional methods least square (ls) and the original rls and it is more robust at high speed mobility. keywords: mimo-ofdm, rls, nn, ber, snr, channel, estimation. 1. introduction the multiple-input-multiple-output orthogonal frequency division multiplexing (mimo-ofdm) technology has been considered as a strong candidate for the next generation wireless communication systems [1]. using multiple transmit as well as receive antennas, a mimoofdm system gives a high data rate without increasing the total transmission power or bandwidth compared to a single antenna system. recently, research suggests that the implementation of mimo-ofdm is more efficient because of the straightforward matrix algebra invoked for processing the mimo-ofdm signals. it thus seems to be an attractive solution for future broadband wireless systems [2]. the arrangement of multiple antennas at the transition end and reception end results increase in the diversity gain refers the quality of signal and multiplexing gain refers the transmission capacity [3, 4, 5]. further, the frequency-selective problem that exists in a conventional wireless system can be well solved by the ofdm technique in the mimo-ofdm system. on the other hand, the performance of mimo-ofdm systems depends largely upon the availability of the knowledge of the channel. however, mimo relies upon the knowledge of channelstate information (csi) at the receiver for data detection and decoding. it has been proved that when the channel is rayleigh fading and perfectly known to the receiver, the capacity of a mimo–ofdm system grows linearly with the number of transmit or receive antennas, whichever is less [1, 6]. therefore, an accurate estimation of the wireless channel is of crucial importance to mimo–ofdm systems. recent works tackled theperformance assessment (both through simulation and measurements) of mimo-ofdm systems in the presence of practicalimpairments, such as synchronization and channel estimation errors [7]. the major challenge faced in mimo-ofdm systems is howto obtain the channel state information accurately and promptlyfor coherent detection of information symbols. the channel stateinformation can be obtained through trainingbased, blind and semiblind channel estimation. the blind channel estimation iscarried this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ alaa abdulameer hassan al-khwarizmi engineering journal, vol. 7, no. 2, pp 36 46 (2011) 37 out by evaluating the statistical information of thechannel and certain properties of the transmitted signals [3]. blind channel estimation has its advantage in that it has nooverhead loss; it is only applicable to slowly time-varyingchannels due to its need for a long data record. in training basedchannel estimation algorithms, training symbols or pilot tonesthat are known a priori to the receiver, are multiplexed alongwith the data stream for channel estimation. semiblindchannel technique is hybrid of blind and training technique,utilizing pilots and other natural constraints to perform channelestimation [3]. the training basedmethods employ known training signals to render accuratechannel estimation. one of the most efficient trainingbasedmethods is the least squares (ls) algorithm. when thefull or partial information of the channel correlation is known, abetter channel estimation performance can be achieved via someminimum mean square error (mmse) methods[1]. in this work, we propose a channel estimation algorithmfor mimo-ofdm systems by employing backpropagationmultilayer neural networks to improve the performance ofa standard recursive least squares (rls) strategy in a rayleigh fading channel. the rls approachis an efficient semi-second-order training that leads toa faster convergence compared with the first-order approaches such as backpropagation (bp) algorithms [8]; and is (rls) widely used for parameter estimation because of its simplicity and fast rates of convergence. the model used by the standard rlsalgorithm is based on multi-layeredperceptrons (mlp). this type of neural network isknown as a supervised network because it requires adesired output in order to learn model. the method described in this paper, however, uses a neural network to learn the parameter updating process of a standard rls algorithm and then to relate the parameters so obtained to the operating conditions. to achieve this, the operating conditions are used as input patterns to a neural network and the neural network is then trained by comparing the parameters obtained from rls algorithms with those from the neural network. this method combines the advantages of the simplicity and speed of convergence of rlsalgorithms with the ability of neural networks tolearn any complex process to any desired accuracy. also, further enhancement of performance can be achieved through maximum diversity space time block coding (stbc) and maximum likelihood (ml) detection at transmission and reception ends respectively. stbcs have theability to greatly reduce the bit error rate (ber) or increase the data rate, and have gained much attention as they are able to integrate the techniques of spatial diversity and channel coding, and can provide significant capacity gains in mimo (ofdm/cdma) systems. the rest of the paper is organized as follows. in the following section the mimo-ofdm with stbc system model is described. the next sectionpresents a general method to channel estimation worked out on rls approach and describes the chosen nn architecture and its application on rls estimation. then, some simulation results and discussionsare given and finally, the least section concludes the paper. 2. system description 2.1. mimo-ofdm system the configuration of multiple antennas can be divided intothree categories [10]: (1) miso (multiple input single output): uses more than one antenna at the transmitter and only oneat the receiver; (2) simo (single input multiple output):uses one transmitting antenna and more than one receivingantenna; and (3) mimo: uses more than one antenna at thetransmitter and more than one at the receiver. by using more than one transmit/receive antenna, multiplechannels are employed between each pair of transmit andreceive antennas. the transmitted signalwill travel through different channels to arrive at thereceiver side. if one of the channels is sufficiently strong,the receiver will be able to recover the transmitted signal. if different channels are independent, then the probabilityof all channels failing is very small [10]. we consider a mimo wireless communication systememploying nt transmit and nr receive antennas (figure(1)), hence, thecorresponding mimo wireless communication channel is constitutedby (nr×nt) propagation links. furthermore, each ofthe corresponding (nr×nt) single-input single-output (siso) propagation links comprises multiple statistically independentcomponents, termed as paths [3, 11, 12, 13, 14, 15]. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ alaa abdulameer hassan al-khwarizmi engineering journal, vol. 7, no. 2, pp 36 46 (2011) modulation demodulationmimo encoder mimo decoder ofdm tx ofdm tx ofdm tx ofdm rx ofdm rx ofdm rx fig.1. mimo architecture. in this system, first of all the binaryinput data is modulated (the data to be transmitted on each sub-carrier is mapped into one of m-ary psk or m-ary qam constellation format, as determined). then, the modulated data is encoded with a mimo encoder andtransmitted from nttransmit antennas. for a rayleigh fading mimo system with nttransmit antennas and nrreceive antennas, the received signal at the jth receive antenna can be expressed as: = ∑ ℎ + …(1) wherexi is the symbol transmitted from the ith transmit antenna, hijis the complex channel coefficients from transmit antenna i to receive antenna j and wjis the additive noise which is modeled as gaussian that is assumed to be independent and identically distributed (i.i.d.) with zero mean and variance = . the transmitted signals fromall transmit antennas overlap in time, space and frequency so that the received signal is asuperposition of all transmitted signals distorted by the channel noise. the channel coefficient matrix h with dimensions (nr×nt)is denoted as: h = ℎ ⋯ ℎ⋮ ⋱ ⋮ℎ ⋯ ℎ …(2) as a result, we can write the received signal given in (1) in the matrix form as: y = hx + w …(3) where, y= ⋮ , x = ⋮ , and w = ⋮ …(4) fig.2. mimo-ofdm system. figure (2) depicts a high level block diagram of the mimo-ofdm system. we consider mimo-ofdm system model with nttransmit antennas and nrreceive antennas.at the transmission time n, a binary data block b is modulated and then passed through the serial-toparallel converter and a complex data matrix s with a length k×n is obtained, where n is the total number of ofdm symbols and k is the total number of subcarriers [3, 15].then the complex data is passed through the mimo encoder to produce ntdata streams, ( , ) for i = 1,…,nt , for transmission over the multipleantennas. each of these signals forms an ofdm block. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ alaa abdulameer hassan al basically, the mimo-ofdm transmitter has ntparallel transmission paths which are very similar to the singleantenna ofdm system, each branch performing pilot insertion, idwt before the final tx signals are up-converted to rf andtransmitted. it is worth noting that the channel encoder and thedigital modulation, in some spatial multiplexing systems, canalso be done per branch, where the modulated signals are thenspace coded using the alamouti algorithm beforetransmitting from multiple antennas not necessarilyimplemented jointly over all the ntbranches [3]. the dwt used here rather than the fft since it is capable of reducing the power of intersymbolinterference (isi) and intercarrier interference (ici), which are caused by the loss in orthogonality between the carriers as a result of the multipath wireless channel (see [16 it analyzes the signal at different frequency bands with different resolutions by decomposingthe signal into an approximation containing coarse (the high-scale, low-frequency componentsof the signal) and detailed information (the low high-frequency components). dwtemploys two sets of functions, known as scaling and wavelet functions, which are associatedwith low pass and high pass filters. the decomposition of the signal into different frequencybands is simply obtained by successi high pass and low pass filtering of the time domainsignal [17, 18]. the original signal first passed through a half-band high pass filter anda half-band low pass filter (see figure (3)) half-band low pass filter removes all frequencies that areabove half of the highest frequency, while a half-band high pass filter removes all frequenciesthat are below half of the highest frequency of the signal. the low pass filtering halves theresolution, but leaves the scale unchanged. the signal is then su (down-sampling, achieved by discarding alternate samples) by two since halfof the number of samples is redundant, according to the nyquist’s rule.we produce two sequences called c frequency) and cd (of high frequency). decomposition halves the time resolution since only half the number of samples then comes to characterize the entire signal. conversely it doubles the frequency resolution, since the frequency band of the signal spans only half the previous frequencyband effectively reducing the uncertainty by half. this procedure, which is also known as subband coding, can be repeated for further decomposition (see figure (4)). at every level, the filtering and sub-sampling will result in al-khwarizmi engineering journal, vol. 7, no. 2, pp ofdm transmitter has parallel transmission paths which are very similar to the singleantenna ofdm system, each branch performing pilot insertion, idwt before converted to rf andtransmitted. it is worth noting that the channel encoder and thedigital modulation, in some spatial stems, canalso be done per branch, where the modulated signals are thenspace-time coded using the alamouti algorithm beforetransmitting from multiple antennas not necessarilyimplemented jointly over all the used here rather than the fft since it is capable of reducing the power of intersymbolinterference (isi) and intercarrier interference (ici), which are caused by the loss in orthogonality between the carriers as a result of (see [16, 17, 18]). analyzes the signal at different frequency bands with different resolutions by decomposingthe signal into an approximation containing coarse frequency componentsof the detailed information (the low-scale, dwtemploys two sets of functions, known as scaling and wavelet functions, which are associatedwith low pass and high pass filters. the decomposition of the signal into different frequencybands is simply obtained by successive pass filtering of the time original signal xi[n] is band high pass filter (see figure (3)). a band low pass filter removes all frequencies areabove half of the highest frequency, while band high pass filter removes all frequenciesthat are below half of the highest frequency of the signal. the low pass filtering halves theresolution, but leaves the scale unchanged. the signal is then sub-sampled , achieved by discarding alternate by two since halfof the number of samples is redundant, according to the nyquist’s we produce two sequences called ca (of low decomposition halves the time resolution since only half the number of samples then comes to characterize the entire signal. conversely it doubles the frequency resolution, since the frequency band of the signal spans only half the ffectively reducing the uncertainty by half. this procedure, which is also known as subband coding, can be repeated for further decomposition (see figure (4)). at every sampling will result in half the number of samples (and he time resolution) and half the frequency bands being spanned (and hence doubles the frequency resolution). fig.3. subband coding; (left): frequency representation, (right): tree-structure fig.4. decomposition of input signal assuming the channel impulse response remains constant during the entire ofdm block, the received signal vector that belongs to the receive antenna, is simply the linear convolution of transmitted symbols and the channel response vector; each of those n is a combination of all the nttransmitted signals and the distorting noise.meanwhile compared to the siso system, it complicates thesystem design regarding to channelestimation and symboldetection due to the hugely increased number of channelcoefficients. subsequently at thereceiver, the performed perreceiver branch. next, thetransmitted symbol per tx antenna iscombined and outputted for the subsequent operations likedigital demodulation and decoding. finally all the input binarydata are recovered with certain ber. , pp 36 46 (2011) half the number of samples (and hence half the time resolution) and half the frequency bands being spanned (and hence doubles the frequency subband coding; (left): frequency domain structure [17]. input signal. assuming the channel impulse response remains constant during the entire ofdm block, the received signal vector that belongs to the jth imply the linear convolution transmitted symbols and the channel impulse nrreceived signals transmitted signals meanwhile compared to the siso system, it complicates thesystem design regarding to channelestimation and due to the hugely increased subsequently at thereceiver, the dwt is performed perreceiver branch. next, antenna iscombined and outputted for the subsequent operations decoding. finally all the input binarydata are recovered with certain this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ alaa abdulameer hassan al-khwarizmi engineering journal, vol. 7, no. 2, pp 36 46 (2011) 40 the output of dwt at the jth receive antenna can be expressed as; ( , ) = ( , ) ( , ) + ( , ) …(5) where ( , )represents the awgn with zero mean and = variance. ( , )denotes the channel frequency response at time for the kth subcarrier between the ith transmit and jth receive antennas. the channel coefficients in frequency domain are obtained as linear combinations of the dispersive channel taps: ( , ) = ∑ ,( ) ⁄ …(6) and the impulse response of the rayleigh fading channel can be expressed as ℎ ( , ) = ∑ ,( ) ( − ) …(7) wherelt denotes the number of non-zero taps, , is the correspondingcomplex amplitude of the lth non-zero tap, tofdm is the ofdm symbol duration and is the delay associated to the lth tap. this delay and variance are assumed to be the same for each transmit-receive channel link. the power of the lth paths are normalized, such that ∑ = 1; [6, 10, 15, 19]. 2.2. space-time block coded (stbc) ofdm stbc introduces redundancy in space, through the addition of multiple antennas, and redundancy in time, through channel coding. its main feature is to provide diversity gain, with very low decoding complexity. in this method (using two transmit antennas), the input data stream is first mapped into symbols using a constellation mapper, and the symbol stream is then divided into two substreams. the symbols and are transmitted from the first and second antenna respectively at time t and the symbols − ∗ and ∗ are transmitted fromthe first and second antenna respectively at time + (the transmit sequences from the two transmit antennas are orthogonal). in this case the code matrix can be given as [3, 11, 13, 15]: x = − ∗ ∗ …(8) the block diagram of the alamouti scheme is shown in figure (5) with one receiver antenna is used at the receiver. the fading channel coefficients from the first and the second transmit antennas to the receive antenna at time t are denoted by h1(t) and h2(t), respectively. by assuming that the channel coefficients do not change in the interval from time t to + , they can be expressed as follows: ℎ ( ) = |ℎ | ℎ ( + ) = |ℎ | …(9) whereℎ and , (i = 1,2) are the amplitude gain and phase shift for the path from antenna i to the receive antenna and tsis the symbol duration. the received signals at the receiver antenna over two consecutive symbol periods for time t and + can be expressed as: ( ) = ℎ + ℎ + ( + ) = − ∗ℎ + ∗ℎ + …(10) so that, = − ∗ ∗ ℎℎ + …(11) or rewrite (11) as in (3) where the channel matrix is give as: h = ℎ ℎℎ∗ −ℎ∗ …(12) now, as in figure (5), and at time n, a data block ( , ), k = 0, 1, …, k-1 wherekis the number of subcarriers, is coded into two different symbol blocks, ( , ){the dwt of },i = 1,2. then the received signal is the superposition of the transmitted signals and can be expressed as: ( , ) = ( , ) ( , ) + ( , ) ( , ) + ( , ) …(13) again, ( , ) denotes the channel frequency response of the multipath channel and the kthsubchannel between the ith transmit and receive antennas. and previously, we assumed that the channel coefficients do not change in the interval from time to time + 1(the channel gains between two adjacent subchannels are approximately equal); then ( , ) = ( + 1, ) = ( ), and the demodulated signal ( , ) is then decoded by the linear maximum-likelihood (ml) space-time decoder [3, 11, 13, 15]: ( , ) = ∗( ) ( , ) + ( ) ∗( + 1, ) ( + 1, ) = ∗( ) ( , ) − ( ) ∗( + 1, ) …(14) this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ alaa abdulameer hassan al finally the estimated symbolsare obtained also[6, 20])so that to minimize the euclidean distance to the received signal. fig 3. proposed channel estimation method 3.1. mlp predictor the most common neural network model is the feed-forward multi-layered perceptrons (mlp). this type of neural network is known as a supervised network because it requires a desired output in order to learn. these networks are widely used for their capability in minimizing cost functions.and among other advantages, they can be entirely made ofsimple electronic devices, such as capacitors, resistors, and operational amplifiers, also suitable for the implementation in very large scale integration(vlsi) technology. this implementation can keep the complexity of the receiver low [21], because it is not directly related to the number of additions and multiplications needed for the problem resolution. thus, to minimize error functions, these network are trained, here, with the use of the rls algorithm. our networkuses two hidden layers where each element i j of a weight ( ij) matrix represents the connection weight connecting neuron downstream layer (i/p, hidden and o/p layers) to neuron j of the upstream layer. now, ŝ ( , ) = ( )| ( , )| + al-khwarizmi engineering journal, vol. 7, no. 2, pp finally the estimated symbolsare obtained (see the euclidean ŝ ( , ) = | ( , ) − ŝ ( + 1, ) = | ( + ( ) ∗( + 1, fig.5. stbc-ofdm system model. proposed channel estimation method the most common neural network model is the layered perceptrons (mlp). this type of neural network is known as a supervised network because it requires a desired these networks are ty in minimizing cost functions.and among other advantages, they can be entirely made ofsimple electronic devices, such as capacitors, resistors, and operational amplifiers, also suitable for the implementation in very large ogy. this implementation can keep the complexity of the , because it is not directly related to the number of additions and multiplications thus, to minimize error functions, these networks are trained, here, with the use of the rls our networkuses two hidden layers where each ) matrix represents the connection weight connecting neuron i of the downstream layer (i/p, hidden and o/p layers) to ) + ( ) …(16) where (. ) is a sigmoid function of each neuron, expressed as, ( ) = , and vector. the required goal, is the learning of associations equations (15) & must restore the desired output in (15) close to the actual one in (16). therefore an error signal will present, ( ). if an error has occurred, then only the weights on the connections from units that sent a non-zero signal to the out adjusted; i.e. ( ) = ( ) + | ( where is the target value (= learning rate (0 < < 1) [22]. the same thing is forŝ ( + 3.2. rls learning algorithm from the viewpoint of adaptive filtering theory, it is well known that the recursive least squares (rls) algorithm is typically an order of magnitude faster than the lms algorithm [ thus, to speed up the convergence of algorithm, the weightsin each layer can be adjusted using the rls algorithm. the rls attempts to minimize the cost function created from the exponentially weighted and windowed sum of the squared error. the channel estimate of ( ) derived and updated as follows. ( , ) = ∑ | , pp 36 46 (2011) ) ∗( ) ( , )| ( + 1, ) −, )| …(15) is a sigmoid function of each neuron, , and ( ) is a bias the required goal, is the learning of quations (15) & (16): the network must restore the desired output in (15) close to the therefore an error signal will if an error has occurred, then only the weights on the connections from units that zero signal to the output unit will be ( , )| …(17) =1) and is the ( 1, ). rls learning algorithm from the viewpoint of adaptive filtering theory, it is well known that the recursive least squares (rls) algorithm is typically an order of magnitude faster than the lms algorithm [23]. thus, to speed up the convergence of mlp , the weightsin each layer can be orithm. the rls attempts to minimize the cost function created from the exponentially weighted and windowed sum of the squared error. ( ) in (15) will be derived and updated as follows. ( , )| …(18) this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ alaa abdulameer hassan al-khwarizmi engineering journal, vol. 7, no. 2, pp 36 46 (2011) 42 where the error signal ( , ) may be expressed as: ( , ) = ( , ) − ∗( ) ( , ) …(19) while denotes the forgetting factor (0 < < 1) that enables the receiver to track the change in a nonstationary environment by forgetting past observed data. the channel estimate ( ) is the one that minimizes ( , ).solving ( , ) ( )= 0 gives [14, 24]: ( ) = ( ) ( ) …(20) where ( )is an autocorrelation function which may be calculated recursively as follows: ( ) = ∑ | ( , )| = ( ) + | ( , )| …(21) while ( )is a crosscorrelation matrix and may be expressed as: ( ) = ∑ | ( , )|| ( , )| = ( ) + | ( , )|| ( , )| …(22) the same procedure is applied for ( +1, )and ( + 1, ). 4. results and discussion the performance limit of mimo-ofdm system for different antenna configuration is quantified through ber which is particularly anattractive measurement for wireless communications. a system equipped with two transmit antennas and arbitrary number of receive antennas is considered for this purpose. in the simulation scenarios the qpsk modulation is used and rayleigh fading radio channel is assumed. in the first simulation, the stbc is applied for two transmit antennas and different number of receive antennas to demonstrate the performance of the considered system atperfect channelknowledge. figure (6) shows the ber performance comparison between 2×2, 2×4 and 2×6 stbc systems. as can be observed from the figure, the 2×6 system performs better than others. for example, the ber of 8*10-5 is achieved at snr = 2 db for 2×6 system, whereas the same ber is achieved at snr = 5db for 2×4 and at snr = 7 db for 2×2 system. it rejects that the ber performance increases as the number of receive antennas increases for the same number of transmit antennas (see [11] to compare these results). fig.6. ber performance comparison between 2×2, 2×4 and 2×6 stbc systems. 0 2 4 6 8 10 12 14 10 -7 10 -6 10 -5 10 -4 10 -3 10 -2 10 -1 10 0 snr (db) be r 2x2 stbc 2x4 stbc 2x6 stbc this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ alaa abdulameer hassan al-khwarizmi engineering journal, vol. 7, no. 2, pp 36 46 (2011) 43 0 2 4 6 8 10 12 14 10 -7 10 -6 10 -5 10 -4 10 -3 10 -2 10 -1 10 0 snr (db) be r ls rls mlp rls perfect csi fig.7. performance comparison between different channel estimations. fig.8. performance of the proposed method in different modulation types. figure (7) illustrates a performance comparison between differenttraining based channel estimations for 2×4 mimo system. anideal channel estimation is also calculated for comparison.from the figure,it can be observed that the ber performance of rls estimation 0 2 4 6 8 10 12 14 10 -7 10 -6 10 -5 10 -4 10 -3 10 -2 10 -1 10 0 snr (db) be r 64qam qam qpsk bpsk this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ alaa abdulameer hassan al-khwarizmi engineering journal, vol. 7, no. 2, pp 36 46 (2011) 44 (with/without intelligent algorithm) isslightly worse than perfect csi, but much better than ls estimation. figure (8) demonstrates the performance of the proposed channelestimation method for different modulation techniques (also under 2×4stbc system). as seen in this figure for a certain level of ber (say 1*10-4), different values obtained of snr against the corresponding modulation type; 1.78 db (bpsk), 2.31 db (qpsk), 5.95 db (qam) and 7.16 db (64qam). 5. conclusion the results of our study can be summarized briefly as follows: 1. an rlsbased mlp algorithm for complex valued neuralnetwork is fully derived. 2. the derived algorithm has been tested over multipath communication channels and implemented using a dwt. the need to this transform is to mitigate theserious interferences, isi and ici appeared while usingthe fft; also there is no need to insert a cyclic prefix between ofdm symbols and then this will eliminate the bandwidth. moreover, the proposed model performance isalso found to be consistent under different signal constellations, and compared with the conventional ls algorithm as described in figures (7&8). 3. the use of the rlsbased mlp for complex valued neuralnetwork has resulted in substantial improvements in termof ber.it is proved that this rate is reduced in all cases as explained previously in the comments on figures (6&7). 6. references [1] feng wan et al, a semiblind channel estimation approach for mimo-ofdm systems, ieee transactions on signal processing, vol. 56, no. 7, july 2008. [2] m. mitra, investigating the impact of spectrum efficient of ofdm-mimo and mc-cdma-mimo communication system for its, journal of theoretical and applied information technology (jatit), 2010. [3] kala praveen bagadi, mimo-ofdm channel estimation using pilot carries, international journal of computer applications (0975 – 8887), vol. 2, no.3, may 2010. [4] eth zurich, mimo-ofdm wireless systems: basics, perspectives, and challenges, ieee wireless communications, august 2006. [5] jari ylioina, iterative detection, decoding, and channel estimation in mimo-ofdm, academic dissertation to be presented with the assent of the faculty of technology of the university of oulu for public defense in auditorium it116, linnanmaa, on 10 june 2010. [6] v. le nir et al, combination of space-time block coding with mc-cdma technique for mimo systems with two, three and four transmit antennas, european union ist research project matrice (multicarrier cdma transmission techniques for integrated broadband cellular systems), 2002. [7] marcello cicerone, channel estimation for mimo-ofdm systems by modal analysis/filtering, ieee transactions on communication, vol. 54, no. 11, november 2006. [8] yong xu et al, generalized rls approach to the training of neural networks, ieee transactions on neural networks, vol. 17, no. 1, january 2006. [9] f. sarabchi, and m. e. kalantari, space time processing with adaptive stbc-ofdm systems, world academy of science, engineering and technology 2009. [10] yuri labrador et al, ofdm mimo space diversity in terrestrial channels, ijcsns international journal of computer science and network security, vol.9, no.10, october 2009. [11] m. t. islam et al, performance and complexity improvement of training based channel estimation in mimo systems, progress in electromagnetics research c, vol. 10, 1-13, 2009. [12] ye (geoffrey) li et al, mimo-ofdm for wireless communications: signal detection with enhanced channel estimation, ieee transactions on communication, vol. 50, no. 9, september 2002. [13] yonghong zeng et al, semiblind channel estimation and equalization for mimo space-time coded ofdm, ieee transactions on circuits and systems-i: regular papers, vol. 53, no. 2, february 2006. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ alaa abdulameer hassan al-khwarizmi engineering journal, vol. 7, no. 2, pp 36 46 (2011) 45 [14] jos akhtman and lajoshanzo, advanced channel estimation for mimo-ofdm in realistic channel conditions, ieee transactions on communication,1-42440353 7/07/$25 ©ieee 2007. [15] i̇lhan baştü rk, iterative channel estimation techniques for multiple input multiple output orthogonal frequency division multiplexing systems, thesis (master of science), graduate school of engineering and sciences of i̇zmir institute of technology, july 2007. [16] b.g. negash and h.nikookar, wavelet based ofdm for wireless channels, international research center for telecommunications-transmission and radar faculty of information technology and systems, delft university of technology, 0-780~-6728-6/010.000/2001 ieee. [17] m. k. lakshmananand h. nikookar, a review of wavelets for digital wireless communication, wireless personal communications (2006) 37: 387–420, doi: 10.1007/s11277-006-9077-y, springer 2006. [18] khaizuran abdullah and zahir m. hussain, studies on dwt-ofdm and fft-ofdm systems, international conference on communication, computer and power (icccp), muscat, february 15-18, 2009. [19] helkamäättänen, mimo-ofdm, s-72.333 postgraduate course in radio communications. [20] somkiat lerkvaranyu and yoshikazu miyanaga, ml detection with symbol estimation for nonlinear distortion of ofdm signal, world academy of science, engineering and technology 2, 2005. [21] romano fantacci et al, a neural network approach to mmse receivers in a dscdma multipath fading environment, ieee transactions on communications, vol. 54, no. 5, may 2006. [22] s. n. sivanandam and m. paulraj, introduction to artificial neural networks, book, vikas publishing hous pvt ltd, 2004. [23] azzedine zerguine et al, recursive leastsquares backpropagation algorithm for stop-and-go decision-directed blind equalization, ieee transactions on neural networks, vol. 13, no. 6, november, 2002. [24] yohei kojima et al, rls channel estimation with adaptive forgetting factor for ds-cdma frequency-domain equalization, ieice transactions on communications, vol. e92-b, no. 5, may 2009. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ 46 ، صفحة2، العدد 7مجلة الخوارزمي الھندسیة المجلد عالء عبداألمیر حسن 36 )2011( 46 تحسین أداء تقدیرات القناة باستعمال الشبكة العصبیة لتدریب خوارزمیة تكرار أقل األجزاء لتقدیر العنصر في أنظمة مزج تقسیمات التردد المتعامد المتعدد االدخاالت المتعدد االخراجات عالء عبداألمیر حسن جامعة بغداد/ الھندسة الخوارزميكیة /المیكاترونكس ھندسة قسم alaa_ah76@yahoo.com: البرید االلكتروني الخالصة ة ان لتقدیمخوارزمی ة ك ذه الدراس وع ھ ر (أن موض دیر العنص زاء لتق ل األج رار أق ھیل أداء ) تك ـبیةكطریقة لتس بكات العصی تخدام الش دة بأس والمعض أ دل الخط اب مع أ (وأحتس دل الخط اقص مع دد ) تن االت المتع دد األدخ دة المتع ردد المتعام یمات الت زج تقس ام م وات نظ دیر لقن ة التق ق خوارزمی اء تطبی أثن بیة " أن خوارزمیة تكرار أقل األجزاء یمكن أعتبارھا فعالة جدا). رایلییف(األخراجات عبر قناة البھت متعدد المسار بكة العص دریب الش ث "أوال: لت ن حی ، م ردد اة للت تجابة القن دیر أس م تق تمرار، ث اة بأس دة أداءا . تدریب الشبكة العصبیة لتقدیر تغییرات القن ة المعتم ل للطریق ائج التمثی رت نت دا " أظھ ت " جی ا قورن أذا م ة رى كخوارزمی رق األخ زاء (الطریقة بغیرھا من الط ل األج ة (أو ) أق ر الذكی ة وغی زاء التقلیدی ل األج رار أق رت ). تك ي أظھ اءة ف ذلك كف دة ك ة المعتم الطریق .فعالیات النظام السریعة this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ (microsoft word \335\321\314 \346\314\343\307\341 \346\321\324\3073247) al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 14, no. 3, september, (2018) p.p. 3247 efficiency enhancement of a dual-axis solar pv panel tracker using water-flow double glazing technique farag mahel mohammed* jamal abdul-kareem mohammed** rasha ali nouri*** *,**,*** department of electromechanical engineering / university of technology / baghdad/ iraq *email: drfaragmahel@yahoo.com ** email: jamalshwesh@gmail.com *** email: eng.rasha1992@yahoo.com (received 26 october 2017; accepted 5 december 2017) https://doi.org/10.22153/kej.2018.12.008 abstract the fall angle of sun rays on the surface of a photovoltaic pv panel and its temperature is negatively affecting the panel electrical energy produced and efficiency. the fall angle problem was commonly solved by using a dual-axis solar tracker that continually maintains the panel orthogonally positioning to the sun rays all day long. this leads to maximum absorption for solar radiation necessary to produce maximum amount of energy and maintain high level of electrical efficiency. to solve the pv panel temperature problem, a water-flow double glazing wfdg technique has been introduced as a new cooling tool to reduce the panel temperature. in this paper, an integration design of the water glazing system with a dual-axis tracker has been accomplished and experimentally tested in order to enhance the pv panel efficiency, especially at hot climates. the proposed glazing system can simultaneously perform two functions, firstly, working as a cooling tool for reducing the stored heat in the pv panel during its work and secondly as an optical filter for sun light spectrum. optimum design factors with their levels for the glazing system were calculated according to taguchi method. test experiments were carried out in baghdad city on the 20th and 21st july 2016 on the tracker with and without using the wfdg system. the obtained results show that, the pv panel temperature with using the wfdg system was significantly dropped by 44% and its efficiency increased maximally by 36.6% at solar irradiance of 1213w/m2 as compared with conventional one. keywords: dual-axis, pv panel, solar tracker, wfdg system, optical filte, efficiency. 1. introduction the solar energy may be utilized in two ways: by collecting the solar radiation and using it in a thermal system or by collecting and converting it directly to electrical energy using a solar photovoltaic pv system. initially, type of the employed pv cells affects the pv module electrical performance. depending upon the kind of these cells and climatic circumstances, a standard pv module transforms (6–20) % of the falling solar radiation into electricity. the residue of solar radiation is transferred into heat, which elevates the module temperature and reduces its efficiency [1]. one of the main obstacles that face the operation of pv panel is the drop in the electric converting efficiency of its cells. the maximum efficiency values of typical monocrystalline pv panel are between (11–15)% [2]. this defect motivated scientists and researchers to enhance the efficiency of the pv panel. the outputs of the pv devices are influenced by different environmental factors, such as module temperature, solar incident irradiance, and solar spectrum distribution. it was found that the pv solar cells work best in cold weather than hot weather. in hot weather, the temperature of the pv cells elevates because of its exposure to farag mahel mohammed al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 3247 (2018) 33 excess in the solar radiation and ambient temperatures. it was found that the maximum production of the output electric power and efficiency of the solar pv cells significantly reduces with the cell temperature increase [1]. thus, the pv cells temperature in hot summer days may be reached more than 70oc. an efficient way to minimize the rate of thermal fall of the pv module and improve its electrical efficiency is by decreasing its surface operating temperature. this could be accomplished by using a cooling technique for the pv module. in the present study, a water-flow double glazing wfdg technique that is used has been proposed as a new cooling tool to enhance the pv module efficiency. on the other side, practically, it was found that the power produced by a pv module is changed with the solar spectrum variation, at a given temperature and irradiance level, over the incident light wavelength range [3]. the second aim of this paper is the building of the wfdg chamber in which used as an optical filter. this filter will be optimized for maximum pv system performance. both of the acrylic glazing sheets and water inside the glazing system could be used as optical filters for solar spectrum; permits to the vis part of the solar spectrum and remove the ir part responsible for heating the solar cell. the cooling and filtering mechanisms represented by the wfdg technique are commonly used for building windows. this technique could efficiently benefit in designing a high efficient solar pv system. the same technique, with some appropriate modifications, may be used here, firstly to control the heat transfer and reducing the operating temperature across pv panel surfaces and secondly filtering the useful solar spectrum to generate electricity across the pv panel terminals and thus improving the overall energy efficiency. the proposed wfdg system in the present work was combined a dual-axis solar tracker system. factors affecting pv panel efficiency the solar pv panel efficiency depends on various factors such as the solar intensity or radiation, the panel operating temperature, and the dust falling on the panel surface [2]. there are many methods might be used to improve the efficiency of the solar pv panel: 1solar tracking, 2pv panel cooling, 3dust cleaning of the panel surface, and 4antireflective coating arc of the panel surface. the present work focuses on the first two methods. when the solar pv cells are exposing to greater amounts of the sunlight, they generate more electric power. the amount of this power is depending on minimizing the fall angle of the sun rays on the pv panel surface. this could be achieved by using a single or dual-axis tracker. the dual-axis tracker continually faces the sun because it can move in two different directions to ensure falling sun ray's perpendicular to the pv panel surface all day from sunrise to sunset, which makes the panel, exposes to larger amount of sun rays and produces maximum power output. therefore, the dual-axis tracker is considered as one of the more effective ways to improve the pv module performance. another factor affecting the pv panel efficiency is the cooling technique. basically, the cooling is divided into two types: passive cooling that utilizes natural convection and conduction for extracting the heat, and active cooling that wastes energy via using fans, pumps, etc. in the two types of cooling, the air and water are commonly used as mediums. however, the cooling by water is better than air for extracting the heat energy from the pv panel at hot climate. it enables the pv panel to work best at elevated levels of temperature and permits, more efficiently, employing the waste heat recovery [4]. many studies had been carried out, in the literature, on cooling the pv systems. the hybrid photovoltaic/thermal pv/t solar system is one of the most popular methods for cooling the pv panels nowadays. furushima and nawata [5] utilized a siphonage as a cooling tool to develop a pv system and evaluated the increase in the pv panel performance during the summer. abdolzadeh and ameri [6] used spraying water above pv cells to reduce the cell's solar reflection and enhance the pv panel performance. zhu et al. [7] used a water immersion cooling system in a high concentration pv system to avoid the cell degradation. gang et al. [8] worked an experimental study on a heat pipe pv/t system performance and confirmed that the system efficiency was improved with the use of cooling by circulated water. eldin et al. [9] used the solar chimney concept to improve the cooling system efficiency by using the particle swarm optimization pso. bahaidarah et al. [10] experimentally studied the performance of a pv module by integrating a water circulated heat exchanger on its back surface. farag mahel mohammed al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 3247 (2018) 34 2. water–flow double glazing system the glazing term is commonly called double glazing (window panes) and more or triple window panes, its space is evacuated or filled with gas so as to decrease heat transfer in the buildings facades. nowadays, the advanced glazing is widespread in the advanced building facades [11]. the incoming solar energy falling on the glazing windows was not invested until an air or water-flow through double panes was proposed by chow et al. [12] to cool window panes in the buildings and blocks the window heat from being transferred into the building interior. the wfdg system is basically made up of a chamber with two glass panes surrounding a void filled by water. when this system is merged within a facade, it absorbs the solar energy to be utilized later as a hot water. the space within the two panes represents a thermal insulator, reduces the amount of energy consumed by an airconditioning system in the building. the wfdg system permits flowing pure water stream across the panes space. a specific cooling device should be used to cool down this water via removing its heat captured. the cold water reduces the glazing panes temperature and obstructs the sun radiation from raising the heat of any devices placed at the back of the glazing system. the water heated by the absorbed solar radiation might be utilized for domestic applications. the flow and the speed of circulating water depend on the cooling need in a specific place at a given time. the wfdg chamber should be connected in the system, sequentially with a feed supply, heat exchanger, water tank, returning pipes, and water pump to control the flow rate of water. the wfdg system has been used with interest in exteriors: curtain walls, facades, skylights and rooftops. the preferred characteristics of this system may be completely invested, so as to minimize the consumption of electric energy. these advantages made the wfdg technique is efficiently employing in solving the energy inefficiencies problems and could be improved and reapplied to enhance the efficiency of the solar pv panel which is suffering from absorptive heating that decreases its electrical efficiency by about 5% for each degree rise in its operating temperature above 50oc [1]. in the present work, the wfdg chamber is proposed to be placed on the front surface of the pv panel. 3. thermal behavior of wfdg system when the solar radiation reaches the outer layer of the wfdg chamber, part of incident solar flux is reflected, another part is transmitted and the rest is absorbed. the absorbed radiation heats up the water confined inside the chamber. the total energy reaches the occupied areas of the pv panel under the chamber is the sum of convective and conductive heat transfers plus the solar energy transmittance which measures the proportion of solar energy that finally ends up in the interior. the wfdg chamber creates an isothermal shield in the glazed surface of the pv's envelope with a temperature lower than its internal temperature. the wfdg system allows transmitting heat from the panel occupied areas into the chamber due to the temperature gradient between the pv inside and the chamber. fig. 1 demonstrates the thermal behavior of the wfdg system. the energy per unit time absorbed q (w/m2) by the water equates the summation of energies acting by [13]; (part of the sun radiation energy absorbed by the glazing + radiation energy transmitted through the glazing + energy exchange with the outside air due to radiation and ordinary/forced convection + energy exchange with the panel inside due to radiation and ordinary convection). � = �� ���� − ��� � = ��� + �� − ℎ�� ��� − ��� � − ℎ�� ��� − ��� � ... (1) where ṁ is the water mass flow rate, kg/s; cp is the water specific heat, j/kg.k; tw is the chamber water temperature; text and tint are the temperature outside and inside, respectively; g is the solar irradiance, w/m2; a is the window surface directed orthogonally to the sun rays direction; αw is the absorption factor of the water chamber; τ is the solar transmittance; hext and hint are the exterior and interior heat transfer coefficients, respectively. 4. optical filters the solar spectrum approximately has 2% ultraviolet (uv), 47% visible (vis) and 51% infrared (ir) of the total solar energy. therefore, the sun vis light and ir radiation constitutes the major fraction of solar radiation reaching earth atmosphere. the solar crystalline pv cells utilize portion of the ir and uv spectrum and full of the vis spectrum [14]. in the literature, many researchers deal with the effect of the solar spectrum on the performance of the pv cells. farag mahel mohammed al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 3247 (2018) 35 huld et al. [3] proposed an empirical model to study this effect. they showed that the total effect of spectral variations was acting by an increase in output power by 1.5% for cadmium telluride and 0.4% for crystalline silicon, with respect to the standard test conditions. it was found that the quantum efficiency of the crystalline pv solar cell is being in the range of wavelength (300 1180) nm of the sun's light. this range includes energy around 86% of the entire solar spectrum energy, the remaining is converting into heat that raises the solar pv cell temperature. therefore, it is necessary to filter out the solar spectrum with wavelengths above the 1180 nm [14]. this could be accomplished by using an optical filter. the optical filter selectively transmits light in a certain range of color wavelengths, whereas preventing others. absorption and transmission of the sun radiation in the double glazing depends upon certain solar spectral properties of glass. glazing panes has transmissivity depending on radiation's wavelength. in particular, clear glass is very transparent to vis and near-infrared nir wavelengths. however, due to the spectral properties of water, it is very transparent to vis wavelengths but opaque to nir wavelengths [14]. one of the superior glazing materials is the acrylic plastic sheets. the acrylic sheet is highly transparent, flexible and has great resistance to breakage. it is an excellent material which can replace glass. it is lightweight, with only half weight of glass for the same size, and it is virtually unaffected by nature. the acrylic sheet actually has optical properties equal to or better than the ordinary glass. the clear acrylic sheet transmits 93% of total light compared to approximately 88% for ordinary plate glass. the acrylic transmits up to 92% of vis light and reflects 8%. it blocks 98% of uv light [14]. therefore, it could be used with the solar pv panels as an optical filter to substantially increase their efficiency. in the literature, many hybrid solar pv/t systems had been designed with optical filters. some studies had shown that clean fluids like water and organic liquids could be used with the solar pv systems as optical filters [1517]. a. qahtan et al. [18] had examined the possibility of using the sustainable glazed water film sgwf as spectrum filter for buildings in the torrid zone. the study showed the effectiveness of this technique in minimizing the transmittance of the solar heat (ir) and maximizing transmittance of the daylight (vis), when 70% of the short-wave ir radiation ranging (1300 2500) nm was absorbed by a thin water film. the water film does not obstruct the vis sun light, but actually raises its transmittance. it concluded that the sgwf is suitable in enhancing the visual and thermal conveniences and decreasing the cooling loads in buildings equipped with glazing facades. when the concentrated solar radiation hits upon the optical filter, the ir spectrum get absorbed by the water and then falls on the solar cells, the remained vis light would be transmitted into the pv cells and transferred into electrical energy as shown in fig. 2. this configuration blocks the excessive rise in the solar cell temperature. therefore, the solution of glazing that was typically used in the building industry could be applied here to be compatibly working with the pv module, which by combining a glazing chamber with circulating water; it will minimize the heat transmittance, increase the capability of blocking the ir radiation and keep the glass transparency for vis light. the circulating water varies the transmittance and the solar factor of the assembly, between the other characteristics, extremely depending on the water temperature. 5. experimental setup 5.1. the solar tracker to construct dual-axis solar tracker unit, some mechanical prerequisites should be considered. all requirements including a 28w, 12v monocrystalline solar pv panel are pointed out in the experimental setup shown in fig. 3. the tracking system is depending in its work on two rotational axis movements, vertical and horizontal. since the solar tracking is a repetitive activity, the plc could be used to control the tracking system. a plc of (ls/glofa-g7mdr20u/dc) type was used and programmed in the ladder diagram language using gmwin 4.0 software. to control the pv panel motion, four light dependent resistors ldrs as light sensors of cds photoresistor type were used to sense the sun's position and continuously direct the panel to receive maximum solar radiation. two 12v dc worm geared motors with 2.4rpm speed and 5n.m torque were used to drive the solar tracker to the desired direction. the control system components and its related connections are shown in fig. 4. 5.2. the wfdg system the wfdg system shown in fig. 3 consists of six components: 1-wfdg chamber, 2water farag mahel mohammed al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 3247 (2018) 36 tank, 3water pump, 4heat exchanger, 5inlet and outlet water pipes, and 6thermostat. the block diagram of the wfdg system is clarified in fig. 5. the wfdg chamber has been built of double panes of clear acrylic plastic sheets, filled with distilled water and fixed in close contact with the pv panel surface. in the present work, experimentally, it was found that using an acrylic sheet with 2 mm thick permits to transmit 98.66% of the total light compared to 92.4% for ordinary plate glass. therefore, the total average solar energy transmittance is about 6% more for acrylic sheet than ordinary glass. as a result, acrylic sheets of 2 mm thick may be effectively used in constructing the proposed glazing chamber. three parameters; wfdg chamber thickness, wfdg chamber position, and flow rate of pumping water were considered with three values for each, to optimize the wfdg system design using taguchi technique. cold water inters one side of the wfdg chamber across two inlets to make regular distribution and departs it as a hot water from one outlet on the other side of the chamber. the water in the chamber is circulated to heat exchanger via a (12v), (0.18a) dc water pump. the flow and speed of the circulating water depend on the cooling need in the specific place at a certain time. the heat captured by the chamber is transported to a water tank to reduce thermal oscillations of the glass panes due to the sun radiation. the tank hot water is pumped to the heat exchanger to cool it. the cooled water inters the chamber through its inlet pipes to cool down the pv panel temperature. the heat exchanger was buried in a basin filled with mud to reduce the temperature of the hot water passing through it. it is a simple idea derived from the ground heat exchanger technique used for cooling buildings [19]. this method of cooling the heat exchanger without using fan is low cost and consumes less electric energy. under this condition, the temperature of the cool water reached (25–30)˚c. therefore, it could be say, the wfdg system had been successfully used as a cooling tool. the system contains a thermostat ranging (30–90)˚c to control the solar panel temperature; its sensor touches the rear surface of the pv panel to sense its temperature. the thermostat was adjustable at 40˚c. when the panel temperature elevates over above 40˚c, the thermostat activates the water pump to run for a time around (5–10) min for cooling the water and then stops. removing the excessive heat from the pv panel via using the wfdg system might be invested to save energy; transfer it from cool demand areas (pv panel) to hot demand areas, i.e. domestic utilization. 6. taguchi optimization method two tests on 19th and 20th june 2016 were carried out. parameters like the solar radiation intensity, ambience temperature, pv panel surface temperature, rated values of panel voltage and current, and water pump flow rate were measured during one hour for each test. the tests were carried out at solar noon with highest values of solar irradiance and ambient temperature. in this paper, analyzing the effect of the wfdg system on the pv panel performance using the taguchi design of experiments doe method was studied. experimental results were collected and analyzed. taguchi method [20] is a systematic approach to analyze and explain the collected data and verify the study aims. in this method, the designer could find the close optimal solution to the proposed problem. this may be used as an initial value for a standard optimization technique. selecting a proper design of the wfdg system depends on the optimum results obtained by using the doe method. three parameters or factors; wfdg chamber thickness (a), pump flow rate (b) which can be regulated by using a rheostat, and wfdg chamber position distance (c) above the solar panel surface, with their three levels would be optimally designed for enhancing the pv panel performance represented by the three responses; solar irradiance efficiency, solar panel temperature, and panel voltage. table 1 illustrates the three factors with their three levels. choosing the control parameters and analyzing their effects on the output responses is considered as the more necessary step in the doe method. choosing a suitable taguchi orthogonal array for the control factors and levels would give the optimum combination of levels. in this work, the three impact factors or parameters were considered with l9 (33) orthogonal array [20] as listed in table 2. 6.1. signal to noise s/n ratio the s/n ratio represents the most significant parameter in the taguchi design methodology. there is several formulas of s/n ratio to get the optimum results. the goal of the current work is how to enhance the solar panel efficiency. this could be achieved by raising the panel voltage and reducing its temperature with the best efficiency of solar irradiance, i.e. the s/n ratio "the smallest farag mahel mohammed al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 3247 (2018) 37 is best to make the system response as small as possible" would be used for panel temperature data and the s/n ratio "the largest is best to make the response as large as possible" would be used to find the irradiance efficiency and panel voltage data. these ratios were calculated as follows [20]: � �⁄ ����� = −10 log%&�'(� … (2) when, the smallest is best � �⁄ ����� = −10 log%&�1 '(⁄ � … (3) when, largest is best where, x is the critical response performance parameters; solar irradiance efficiency, pv panel temperature, or pv panel voltage. the values of the calculated s/n ratio for all nine experimental results were recorded in table 3 for each parameter of the system response. the panel temperature values were measured after using the wfdg chamber when 56˚c panel temperature was chosen as a reference value measured before using the chamber. the irradiance efficiency acts the ratio of irradiance measured on the pv panel surface under the chamber to its value measured over the chamber surface. 6.2. analysis of means anom the anom is an analytic tool of data taken from the orthogonal array experiments. the anom values could be found from the average values of s/n ratio at a certain level for any factor. these values were listed as in table 4 for the three performance responses: irradiance efficiency, panel temperature, and panel voltage. for example, for the effect of the wfdg chamber thick factor on the solar intensity shown in table 4, the level 1 value could be represented by the calculated mean s/n ratios; first three rows of the l9 array (-0.149, -0.142, -0.134) listed in table 3 which depends upon the corresponding array (first three experiments for level 1 and factor a) shown in table 2. the same scenario was reapplying on other factors and levels. the optimal level pointed out by the underlined value shown in table 4 represents the average value of s/n ratio required to get the best performance. therefore, the optimum level combination for the solar irradiance efficiency response is a1b3c1, which equivalent to factor a with level 1, factor b with level 3, and factor c with level 1, meaning (1cm wfdg chamber thickness, 28.2 cm3/sec water flow rate, and 0cm chamber position). also, for the pv panel temperature, the optimal arrangement level is a3b2c1, i.e. (2 cm thickness, 42.3 cm3/sec water flow rate, and 0 cm position), while the optimum levels arrangement for the pv panel voltage is a2b3c1, that means (1.5cm thickness, 28.2 cm3/sec water flow rate and 0cm position). the (max–min) column shown in table 4 represents the difference between the highest and lowest s/n values for the three levels and each factor, e.g. for solar irradiance efficiency with factor a, the (max-min) = (-0.1416) (0.2006) = 0.0591. the same manner can be used to find the remained column values for other two factors (0.0591, 0.0151, and 0.0012). this column is the more influential factor for choosing the system response parameters. it could be found according to the rank parameter. the rank column is numbered from the highest to the lowest (max–min) value. so, from the rank value, it was found that the chamber thick (factor a) has more effectiveness on the irradiance efficiency than other two factors (b and then c), respectively. same scenario can reapply to complete the (max-min) and rank columns in table 4 for the other responses; the pv panel temperature and voltage. it can be noticed from the table that the position of the chamber (factor c) is the more influential factor on the temperature and voltage of the pv panel than other two factors (a and b). graphically, fig. 6 shows the values of the mean of s/n ratios versus the levels and factors for the three system responses. it can be noted that level 1 for factor c (chamber position) has mean s/n ratios with optimum values for the three responses, which gives the maximum efficiency of irradiance, minimum pv panel temperature, and maximum pv panel voltage. this means that, placing the chamber to be in touch with the pv panel cells surface is the best choice. to get maximum irradiance efficiency, levels (1, 3, and 1) for the corresponding factors (a, b and c), respectively, were chosen. while the levels (3, 2, and 1) for the corresponding factors (a, b, and c) could be used to obtain minimum panel temperature. also, levels (2, 3, and 1) of the corresponding factors (a, b, and c) are representing the optimal level values which give the maximum value of panel voltage that is the goal of the present work. therefore, the wfdg system offers the highest enhancement of performance when the chamber thickness = 1.5cm, water flow rate = 28.2 cm3/sec and the chamber is directly placing on the panel surface. as a result, the wfdg chamber was constructing with (l×w×t = 43×42×1.5) cm dimensions. where, l and w represent the same corresponding dimensions of the pv panel surface. farag mahel mohammed al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 3247 (2018) 38 6.3. analysis of variance anova the anova [20] is a statistical analysis tool used for analyzing the effect of the design factors on the overall difference of test results. the parameter which is statistically more important than others could be distinguished by the anova tests. table 5 illustrates the anova analysis results. from the table, the sum of square of deviation ss column, due to any factor can be calculated according to following equation: �� = 3 ∑ �+� − +,�(� �-% ... (4) where ηi is the mean value of s/n ratio for the ith experiments for the factors a, b or c and levels, ηm is the total mean values of s/n ratios for any response which equal (sum of s/n ratios divided by 9), i is the number level for each factor, n=3 is the number of experiments at that level, e.g. for the irradiance response in the table 4, the factor a value in three levels; a1, a2, and a3 is equal to ss = 3 [(a1ηm) 2 + (a2ηm) 2 + (a3ηm) 2]. the ss for other factors could be calculated in the same manner. for any factor, the degrees of freedom d.f is equal to the number of factor's levels minus one = 3-1=2. the d.f value for the total sum of squares is equal to the number of rows in the designed matrix 1 = 9-1= 8. the d.f value of the error is equal to the d.f of the total sum of squares minus the sum of the d.f's for all factors = 8-6 =2. the mean square value = ms = ss/d.f. the f ratio in table 5 can be calculated as the ratio of mean square to the error mean square for any factor = ms/ems. the contribution column in the table could be found by dividing the ss value for each factor by the total sum of ss. from the contribution column, e.g. for the solar irradiance efficiency, it was found that factor a has the significant effect on the system response, that highly contributes to the total sum of squares by about; (0.005473/0.005823)×100 = 93.99 %. so, it has the largest influence on the irradiance efficiency than other factors, followed by factor b with 5.86% and then c with 0.04%. also, for the panel temperature response, the factor c has the largest contribution of 65.04% followed by factor b of 12.00% and then c with 11.82%. in same manner, factor c is the significant factor for panel voltage followed by factor a and then b. in other word, according to the contribution value, the wfdg chamber thickness factor has the greatest influence on the solar irradiance process than others factors, pumping water flow rate and then chamber position. also, the chamber position is the more effect factor on both of the solar panel temperature and voltage than other two factors. from tables 4 and 5, it can be concluded that the anom and anova results are perfectly matched, and three concepts can be deduced, that is the chamber configuration would be: 1. 1cm thickness has more effect on irradiance efficiency, however it doesn't cause minimum pv panel temperature, moreover, it is not adequate to achieve a maximum panel voltage. 2. 2cm thickness verifies a minimum panel temperature, but it doesn't achieve the maximum panel voltage; this is because of the waste increase in the sunlight irradiance. 3. 1.5cm thickness achieves a maximum output panel voltage, the more influence parameter on the panel efficiency. this configuration can decrease the value of irradiance waste less than using 2cm chamber thickness. also, it can be noticed from tables that level 3 for factor b and level 1 for factor c give the maximum output panel voltage. as a result, the proposed wfdg system can achieve the highest performance enhancement with specifications; 1.5cm chamber thick, 28.2cm3/sec water flow rate and 0 cm chamber distance (the chamber is directly touched the panel surface). this arrangement reduces the irradiance waste in the sunlight, increases the heat rejected, reduces the pv panel temperature, increases the panel voltage, and consequently increases the panel efficiency. therefore, the chamber could be optimally built with (43×42×1.5) cm dimensions. 6.4. confirmation test the confirmation test represents the final step of doe method. this test has been conducted at optimal levels. since, the optimum levels for each response were introduced. the optimal values of the s/n ratio under the optimal conditions ηopt can be found as follows [20]: +.� = +, + ∑ �+� − +,�� �-% ... (5) this test had been used for comparing the values of the experimental s/n ratios with the predicted s/n ratios. the total mean value of the s/n ratio ηm was found according to its values labeled in table 3 for each performance response. the ηi values act the underlying values of the mean s/n ratio at optimum conditions as in table 4. n is the number of design factors. therefore, the predicted s/n values were found and the confirmatory test results were tabulated as in table 6. it can be shown that, the experimental and predicted test results are close together with an error does not exceed 3.9 %. farag mahel mohammed al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 3247 (2018) 39 7. results and discussion the performance experimental results for the dual-axis solar tracking unit combined with the wfdg system were collected. the wfdg chamber was designed with optimum factors; 1.5 cm chamber thick, 28.2cm3/sec water flow rate and 0 cm chamber position to achieve the highest efficiency. to find the electrical efficiency of the solar pv panel combined with the glazing system, some parameters, like the panel voltage vpv and current ipv, the temperature of the panel surface, the ambience temperature, the inlet/outlet temperature of flowing water, water flow rate, and solar radiation intensity gs were measured. the performance of the overall system is depending on sun's position with respect to the pv panel. the pv panel tracks the greatest sun light intensity via its light sensors according to a ladder program loaded into the plc. the solar panel surface area as is 0.1806m2. all the necessary specifications for the solar pv panel and wfdg system are listed in table 7. the output power, pout and input power, pin for the solar pv panel and its electric efficiency ηelec had been found by [1]: +�/�0 = 1234 156 = 789 :89 ;< =< … (6) in the present work, the obtained readings were conducted in two test cases. these readings were recorded using the measurements devices listed in table 8. they are distributed on two successive days, the19th and 20th june 2016 from sunrise to sunset. in the first test day, only the dual-axis tracking system with no use of the wfdg unit system (case 1) was applied. in the second test day, the tracking system was integrated with the wfdg system (case 2). fig. 7 shows the history of the incident solar irradiance on the pv panel on 19th and 20th june 2016 for the two cases, respectively. the figure shows the increase in the irradiance through the period 7:00am – 1:30pm and the decrease after 1:30pm for both system cases (tracker without and with the glazing system). it could be seen that the difference in the solar irradiance for the two cases is relatively small and not exceed 1.8%. the rise in the irradiance and ambient temperature causes increase in the pv panel temperature. in fig. 8, the panel temperature in case 1 at test day had been increased within 7:00am–1:00pm among (40.1–59.7)˚c because of the ambient temperature increase around (34.3 – 46.5)˚c. the panel temperature, after 1:00pm decreases as the ambient temperature decreases, while in case 2, the panel temperature becomes between (36.5 – 38.8)˚c. this range is attributed to the use of glazing system (case 2), which tries to maintain the panel temperature approximately around 40˚c by about (3.5 – 1.2)˚c reduction as the panel receives irradiance not exceed 1150w/m2 and around (2 – 0.2)˚c reduction with irradiance value more than 1150 w/m2. the electric power taken from the pv panel depends upon the measured values of the panel voltage and current. this power basically is proportional to the sun irradiance. in fig. 9, the solar panel generates maximum output power values at a time among 12:30pm – 1:30pm. the panel power would be decreased gradually after 1:00pm when the irradiance decreases. the output pv panel power with case 2 had been elevated maximally by about 18.66%, and averagely about 14.96% comparing with case 1. the maximum output power of the pv panel was 27.78w in the case 2 when maximum voltage and current were 20.84v and 1.333a, while it was 23.41w in the case 1 when maximum voltage and current were 18.7v and 1.252a. the electric efficiency curve of the solar panel was shown in fig. 10. it is shown that the efficiency increases with time until 1:00pm and then decreases with the irradiance decrease. the figure shows that the maximum efficiency is 12.7% in case 2, and 10.5% in case 1. so, it can be concluded that the efficiency in the case 2 is higher than case 1, maximally by around 20.9% and averagely 16.5%. this is because of being the panel temperature in case 2 was decreased maximally by about 34.6% and averagely 22.4% comparing with case 1. second experimental tests were conducted in 20th and 21st in july 2016 for finding out the temperature effect along the daytime on the pv panel efficiency in the tracking system mode for the two cases as shown in fig.11. in this month, baghdad city is characterizing by its highest temperatures through the year. it could be shown that the pv panel temperature of the system in case 1 was within (46–71.2)˚c through the period 7:00am-1:00pm as the ambient temperature was around (36.1–52)˚c, respectively and decreased after 1:00pm, while, in the case 2, the panel temperature decreased into (37.7–39.8)˚c. the maximum electric efficiency of the pv panel had been 12.7% at solar irradiance of 1213w/m2 in the case 2, whereas, it was 9.3% in the case 1. as a result, reducing the panel temperature in case 2 maximally by 44% and averagely 34.2% as compared with case 1, causes the solar panel efficiency to be increased in the case 2 more than case 1, maximally by about 36.6% and averagely by 31.4%, respectively. farag mahel mohammed al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 3247 (2018) 40 table 1, the proposed factors and levels. factors level-1 level-2 level-3 awfdg chamber thickness, cm 1 1.5 2 bwater flow rate, cm3/sec 87.3 42.3 28.2 cwfdg chamber position, cm 0 1 2 table 2، numbering of experiments using l9 orthogonal array. table 3, s/n ratio values of the experimental results. table 4, mean s/n ratios for different factors (underlined value represents the optimum level). exp no. factors and levels wfdg chamber thickness, a water flow rate, b wfdg chamber position, c level level level 1 2 3 4 5 6 7 8 9 1 1 1 2 2 2 3 3 3 1 2 3 1 2 3 1 2 3 1 2 3 2 3 1 3 1 2 exp no. irradiance efficiency panel temperature panel voltage value, % s/n ratio, db value, ˚c s/n ratio, db value,v s/n ratio, db 1 2 3 4 5 6 7 8 9 98.30 98.38 98.47 98.10 98.17 98.25 97.61 97.74 97.80 -0.149 -0.142 -0.134 -0.167 -0.160 -0.153 -0.210 -0.199 -0.193 52.0 54.3 54.5 54.4 54.6 46.0 54.7 40.6 54.0 -34.320 -34.696 -34.728 -34.712 -34.744 -33.255 -34.760 -32.171 -34.648 19.35 19.07 19.05 19.15 19.10 19.70 19.02 19.08 19.06 25.734 25.607 25.598 25.643 25.621 25.889 25.584 25.612 25.602 factor average of s/n ratio values max−min rank optimal levels level-1 level-2 level-3 irradiance efficiency, % awfdg chamber thickness, cm 0.1416 0.1601 0.2006 0.0591 1 a1 b3 c1 bwater flow rate, cm3/sec 0.1752 0.1669 0.1602 0.0151 2 cwfdg chamber position (cm) 0.1669 0.1672 0.1682 0.0012 3 panel temperature, ˚c awfdg chamber thickness, cm 34.5813 34.2370 33.8594 0.7220 3 a3 b2 c1 bwater flow rate, cm3/sec 34.5973 33.8701 34.2103 0.7271 2 cwfdg chamber position, cm 33.2486 34.6853 34.7438 1.4953 1 panel voltage, v awfdg chamber thickness, cm 25.6462 25.7178 25.5994 0.1184 2 a2 b3 c1 bwater flow rate, cm3/sec 25.6537 25.6131 25.6966 0.0835 3 cwfdg chamber position, cm 25.7448 25.6176 25.6009 0.1439 1 farag mahel mohammed al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 3247 (2018) 41 table 5, results of anova. factors sum of squares ss degree of freedom d.f mean squares ms f ratio % contribution % irradiance efficiency, % awfdg chamber thickness, cm 0.005473 2 0.0027363 841.6179 93.99 bwater flow rate, cm3/sec 0.000341 2 0.0001706 52.4685 5.86 cwfdg chamber position, cm 0.0000024 2 0.0000012 0.3674 0.04 error mean square ems 0.0000065 2 0.00000325 0.11 total sum 0.005823 8 100.00 panel temperature, ˚c awfdg chamber thickness, cm 0.7824 2 0.3912 1.0623 11.82 bwater flow rate, cm3/sec 0.7942 2 0.3971 1.0783 12.00 cwfdg chamber position, cm 4.3033 2 2.1517 5.8429 65.04 error mean square, ems 0.7365 2 0.3683 11.13 total sum 6.6164 8 100.00 panel voltage, v awfdg chamber thickness, cm 0.021328 2 0.0106642 2.4618 27.48 bwater flow rate, cm3/sec 0.010455 2 0.0052276 1.2068 13.47 cwfdg chamber position, cm 0.037174 2 0.0185872 4.2908 47.89 error mean square ems 0.008664 2 0.0043318 11.16 total sum 0.077622 8 100.00 table 6, results of confirmation. optimal factors factors optimal levels experimental values predicted values error, % irradiance efficiency, % pv panel temperature, ˚c pv panel voltage, v a1 b3 c1 a3 b2 c1 a2 b3 c1 98.47 40.6 19.70 98.47 42.29 19.61 0.00 3.9 0.45 table 7, pv panel and wfdg system specifications. solar pv panel specifications wfdg system specification parameter value parameter value type mono-si glazing chamber rated maximum power, pmax 28w chamber dimensions (43×42×1.5)cm operating voltage, vmp 21v material acrylic glass operating current, imp 1.33a number of sheets two sheets open-circuit voltage, voc 23.12v sheet thickness 2mm short-circuit current, isc 1.515a thermal conductivity 0.2 w/m.˚c efficiency, ηele 15 % chamber weight 3.43 gm weight 2.5 kg heat exchanger dimensions 43×42×2.4 cm type finned u tube air cooled without fan installation frame no. of cells 36 material copper pipes standard test conditions, stc aluminum foil hydrophilic or bare air mass, am 1.5 fines flat cell temperature, tc 25 ˚c dimensions 25×25×8 cm solar irradiance, gs 1000 w/m2 pipes external diameter 1cm table 8, specifications and accuracy of measurement devices. items model ranges accuracy digital multimeter ut136c dcv: 400m/4/40/400/500v acv: 400m/4/40/400/500v dca: 400 /4m/40m/400m/4/10a aca: 400 /4m/40m/400m/4/10a temperature: -40 ~1000 freq: 10hz~10mhz ±0.8% ±1.2% ±1.0% ±1.2% ±2.5% ±0.5% digital thermometer pt-5 temperatures range: -50~110 ˚c ±1˚c solar power meter spm-1116sd irradiance range: (0-2000) w/m2 ±10w/m2 farag mahel mohammed al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 3247 (2018) 42 fig. 1. thermal performance of the wfdg system. fig. 2. wfdg system working as an optical filter. (a) front view (b) back view fig. 3. experimental setup of the whole system:1base, 2-cylindrical base, 3-central shaft, 4-pv panel, 5-driver pulley, 6motor m1, 7-driven pulley, 8-vbelt, 9-motor m2, 10-frame, 11-pillow block bearing, 12: ldr sensors s1-s4, 13: limit switches ls1-ls4, 14-dc battery, 15-control board, 16wfdg chamber, 17-chamber inlets, 18-chamber outlet, 19-heat exchanger in mud basin, 20-water pump, 21-heat exchanger inlet/outlet, 22-water tank, 23-thermostst and its sensor, 24-rheost, 25main switch s-sw, 26-digital meter. fig. 4. control system: 1-plc, 2-a/d converter, 3dc/dc converter, system 4-relays, 5-main switch, 6-connectors. water water in water out incoming solar radiation solar photovoltaic cell glass sheet filtered solar radiation 20 19 21 22 22 25 24 3 11 26 23 13 16 1 2 3 7 4 8 9 1 13 15 16 17 1 12 5 11 6 1 farag mahel mohammed al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 3247 (2018) 43 fig. 5. block diagram of the wfdg . a) solar irradiance efficiency b) pv panel temperature c) pv panel voltage fig. 6. the mean s/n ratios with levels for various responses. fig. 7. solar irradiance through day time. farag mahel mohammed al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 3247 (2018) 44 fig. 8. panel temperature through day time. fig. 9. panel output power through day time. fig. 10. panel efficiency through day time. fig. 11. hourly performance comparison of the tracking pv panel system. farag mahel mohammed al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 3247 (2018) 45 8. conclusions in this paper, a water-flow double glazing wfdg system was designed, implemented, and integrated with a plc-based automatic dual-axis solar pv tracker to enhance its electrical efficiency. designing the experiments optimally was accomplished by taguchi technique. some conclusions might be extracted from the experimental results 1. the new wfdg technique wastes least possible amount of cooling water and consumes lowest electric energy than the traditional cooling methods. 2. due to good spectral properties, the wfdg chamber could be used as an optical filter. therefore, the wfdg system could execute two jobs, necessary to improve the efficiency of the pv panel; cooling down the pv panel and filtering out the incident sun's light on it. 3. the necessary factors of the wfdg system required for optimizing the performance of the pv panel determined by using the taguchi doe method were found as; 1.5cm glazing chamber thickness, 28.2 cm3/sec pumping water flow rate, and 0cm glazing chamber distance from the pv panel surface. 4. the position factor of the glazing chamber has greater effect on the temperature and voltage of the pv panel than the other two factors, while the glazing thickness factor is more effective on the irradiance than other two factors. 5. the wfdg system efficiency is reduced with the increase of the glazing position. 6. the pv panel temperature in the combined system was maintained around (36 – 40)0c and the maximum efficiency at 12.7% when the ambient exceed 500c. it was shown that the panel temperature reduction in the combined system was maximally about 44% and averagely 34.2%, with respect to conventional system. this contributes to increase the solar panel efficiency maximally by 36.6% and averagely 31.4% at 1213w/m2 solar irradiance, comparing with the conventional system. 9. references [1] dubey, s., sarvaiya, j. n. and seshadri, b. 2013. temperature dependent photovoltaic (pv) efficiency and its effect on pv production in the world a review. pv asia pacific conference 2012, energy procedia, vol. 33, 311–321. [2] c.s. solanki, solar photovoltaics: fundamentals, technologies and applications, 3rd revised edition prentice hall india learning private limited 2015. [3] t. huld, t. sample, e.d. dunlop, a simple model for estimating the influence of spectrum variations on pv performance, proceedings of the 24th european photovoltaic solar energy conference, hamburg, germany, september 2009, pp. 3385-3389. [4] f.g. čabo, s. nižetić, t.g. marco, photovoltaic panels: a review of the cooling techniques, transactions of famena xl – 40(si) (2016) 63–74. [5] k. furushima, y. nawata, performance evaluation of photovoltaic power generation system equipped with a cooling device utilizing siphonage, journal solar energy engineering asme 128 (2) (2005) 146–151. [6] m. abdolzadeh, m. ameri, improving the effectiveness of a photovoltaic water pumping system by spraying water over the front of photovoltaic cells, renewable energy 34 (1) (2009) 91–96. [7] l. zhu, r.f. boehm, y. wang, c. halford, y. sun, water immersion cooling of pv cells in a high concentration system, solar energy materials and solar cells 95 (2) (2011) 538– 545. [8] p. gang, f. huide, z. huijuan, j. jie, performa nce study and parametric analysis of a novel heat pipe pv/t system, energy 37 (1) (2012) 384–395. [9] m. sh-eldin, f.o. alghoul, a. abouhnik, k. sopian, m. ae. muftah, predication of air velocity in solar chimney using rbfnn, proceedings – 2012 7th ieee international conference on computing and convergence technology iccct 2012, seoul, 3-5 december 2012, pp. 976 – 979. [10] h. bahaidarah, a. subhan, p. gandhidasan, s. rehman, performance evaluation of a pv (photovoltaic) module by back surface water cooling for hot climatic conditions, energy 59 (2013) 445–453. [11] s. ghoshal, s. neogi, advance glazing system – energy efficiency approach for buildings a review, energy procedia 54 (2014) 352–358. 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[20] c. zang, m.i. friswell, j.e. mottershead, a review of robust optimal design and its application in dynamics, computers and structures 83 (4) (2005) 315–326. )2018( 32-47، صفحة 3د، العد14دجلة الخوارزمي الهندسية المجلمفرج محل محمد 47 غطائه ضمن المتدفق الماء خدامبإست المحاور ثنائي المقتفي الشمسي اللوح كفاءةِ تحسين المزدوجِ الزجاجي رشا علي نوري *** جمال عبد الكريم محمد ** فرج محل محمد * العراق /الكهروميكانيكية / الجامعة التكنولوجية / بغداد قسم الهندسة *** ، **،* drfaragmahel@yahoo.com :البريد االلكتروني* jamalshwesh@gmail.com**البريد االلكتروني: yahoo.com1992eng.rasha@***البريد االلكتروني: الخالصة ً يُؤثّرانِ هحرارت ودرجة الشمسي اللوح سطحِ على الشمس أشعةِ سقوط زاويةَ إنّ سقوطال زاويةِ مشكلة أن. وكفاءته لوحل الكهربائية الطاقة على سلبيا يُؤدّي هذا. اليوم ِطوال الشمس أشعةِ مع متعامد مستمر بشكل اللوح بقييُ والذي المحوِرين ذات الشمسي (المقتفي) التتبع منظومة ستخدامبإ حلها يتم ما عادةً تمّ فقد الحرارة مشكلةَ لَحلّ . ئيةالكهربا الكفاءة ِمن عالية اتمستوى وعند الطاقةِ ِمن القصوى الكميةِ تاجإلن والضروريِ الشمسيِ لإلشعاعِ أقصى إمتصاِص إلى تصميم تمّ البحث، هذه في. اللوح حرارة درجة خفيضلت جديدةِ بريدت طريقةبوصفها الماء خاللها يتدفقِ والتي (المزججة) زجاجيةال غرفةال تقنية استخدام في السيما الشمسي، اللوح كفاءةَ تحسين لغرض عليها المختبرية التجارب واجريت المحاور ثنائية التتبع منظومة َمعبالتكامل المقترحة التزجيج منظوِمة ً هاملعَ أثناء اللوح داخل في الَمْخُزونة الحرارةِ لتقليل تبريد أداة يَعَمل أوالً، آني، بشكل ينوظيفت يُؤدّي أَنْ يُْمِكنُ الُمقتََرحِ التزجيج نظام. الحارِ المناخِ وثانيا ّ التزجيج نظامِ لقيم مختلفة مستوياتوب األمثل التصميمُ معامالت حساب تمّ . الضوئي للطيفِ ابصري امرِشح في اإلختبارِ تجارب تنفيذ تمّ . وتشيتاك لطريقةِ وفقا تاِئجالن ينتبُ . هاوبدون التزجيج منظومة مقترح إستعمال عفي حالتين م التتبع منظومة على ٢٠١٦ تموز/يوليو ِمنْ نوالعشري والحادي العشرين في بغداد مدينةِ % ٣٦٫٦بحاولي الكهربائية هاكفاءت وزادت %٤٤ بمقدار ملحوظ بشكل طتبهَ التزجيج منظومة بإستعمال الشمسي اللوح الحرارة درجةَ بأّن، المستحصلة .2w/m ١٢١٣ شمسي اشعاع قيمة عند التقليدية المنظومة مع بالمقارنة عند يعرب عمر ناجي18-13 al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 7, no. 3, pp 13 18 (2011) fuzzy control of the robotic hands catching force using muscle wires actuator yarub omer naji al-azzawi department of mechatronics/ al-khwarizmi college of engineering/ university of baghdad (received 6 february 2011; accepted 19 jun 2011) abstract the aim of this research is controlling the amount of the robotic hand catching force using the artificial muscle wire as an actuator to achieve the desired response of the robotic hand in order to catch different things without destroying or dropping them; where the process is to be similar to that of human hand catching way. the proper selection of the amount of the catching force is achieved through out simulation using the fuzzy control technique. the mechanism of the arrangement of the muscle wires is proposed to achieve good force selections. the results indicate the feasibility of using this proposed technique which mimics human reasoning where as the weight of the caught peace increases, the force increases also with approximately the same amount of increment. keywords: muscle wires, shape memory alloy, robotics hands. 1. introduction it is still hardly desired to control the motion and catching force of the robotic hand to make an excellent response to catch different things without destroying them or slipping them down. pedram afshar and yoky matsuoka [1] indicate that the neural-based control of a robotic hand has many clinical and engineering applications. current approaches to this problem have been limited due to a lack of understanding of the relationship between neural signals and dynamic finger movements. here, a technique is presented to predict index finger joint angles from neural signals recorded from the associated muscles. the neural signals were converted to a torque estimate (ebte) and then input to artificial neural networks. the networks predict the finger position more closely when the input to the networks is torque estimates rather than neural signals. vishalini bundhoo and edward j. park [2] focus on the design and modeling of a prosthetic finger for children. conventional prosthetic hands are simple grippers that only restore the very basic grasping capabilities of the human hand. novel design methodologies were required in order to address the issue of low functionality of prosthetic hands while still meeting their mass and size requirements. a biomimetic approach to prosthetic hand design proposed. the musculosketal characteristics of the human hand are studied in order to extract elements that are essential in the design of a biomechanically accurate hand. a 4 dof finger design that closely mimics the size and kinematics of the human finger is presented. the design proposes to use sma-driven tendon wires that are directly attached to the finger structure, in a manner similar to the natural tendons and muscles. a kinematic analysis of the proposed finger, which defines the relationship between the motion of its joints and the corresponding sma artificial muscle contraction ranges, was presented. the results of a torque analysis carried out to evaluate sma wire diameter and actuation forces required was also presented. megan grimm, a. antonio arroyo, michael nechyba [3] introduce the thing which is a robotic hand with three digits, a pronating opposable thumb, and a 2 d.o.f. wrist. designed to more accurately model of human hand positioning and grasping capabilities than previous models, thing is controlled by a flex-sensor-equipped glove yarub omer naji al-azzawi al-khwarizmi engineering journal, vol. 7, no. 3, pp 13 18 (2011) 14 which relays the user’s finger positions by means of flex sensors. it will also, by the time of publication, incorporate an image-processing system for determination of wrist posture. the proposed design in this research is using an artificial muscle wire (shape-memory-alloy sma) as an actuator. muscle wires belong to a class of metal alloys displaying a property called shape memory effect (sme), and when heated they will recover their original, shorter length and contract with a usable amount of force in the process [4]. the connection of muscle wires mechanically in parallel as proposed in this research makes the increment of the amount of force without affecting the amount of contraction possible and this help in the application of the robotics hand to catching different things without problem association. 2. the proposed technique of catchment there is a very different and much newer way to create motion from by using shape memory alloys (sma). these special metals undergo changes in shape when heated or cooled and do so with great force. the required gripper movements are ensured from the different activations of the connected muscle wires in series as shown in figure [1]. fig.1. schematic of mws connection in series [5]. the important part of this job is the limitation of the amount of the catching force; that is the hand to catch different things without slipping or destroying them. the selection of the amount of the force depends on the size (cross section) of the used muscle wire and the type of the alloy that this muscle wire is made of, where each size and type give an absolute amount of force [4]. but if it is needed to control or select the desired amount of catching force to catch the present piece or particle, the number of parallel (mechanically) muscle wires of the same size and type or different must be selected and the process of selection must be through a control strategy. the proposed hands' actuator consists of two levels; level(1) is responsible of the required hands' tips motions, and level(2) works as a generator that generates the required amount of grasping force as shown in figure [2]. fig.2. the proposed robotics hand. the mechanical and electrical characteristics of the used sma are: 1. type: flexinol 375 ht 2. diameter: 375 µm 3. activation temp: 90⁰c 4. resistance: 8 ω/m 5. recommended current: 2750 ma 6. rec. recovery force: 2000 grams 7. rec. deformation force: 393 grams 8. rec. deformation: 3-5% mws connected mechanically in parallel level 1 level 2 available hand yarub omer naji al-azzawi al-khwarizmi engineering journal, vol. 7, no. 3, pp 13 18 (2011) 15 the characteristics and dimensions of the used robotic hand 1. stainless steel prostheses partial hand 2. single degree of freedom hand 3. two fingered 4. length: 10 cm 5. wight: 100 grams 6. approximate fingers cross section: 0.05 each 3. control strategy the pieces weight, size, and the coefficient of friction between the piece and the finger tip are all unknowns to the robot; therefore, the robot controller must take this into account, where the robotic hand should catch any piece without the need to know the preceding parameters. it is important also to know that the dropping of the piece results from not enough catching force to prevent slipping of the piece. figure [3] indicates the robotics hand catching a piece [6]. from figure [3], to ensure catching the piece, the total friction force (2ff) must equal the value of the piece weight [6]: from the free-body-diagram (fbd) shown in figure [3.b] where; µ = coefficient of friction. fg = pressing force (grasping force). w = piece weight. so the grasping force fg will be: the two parameters (µ, w) upon them the grasping force depends are unknowns; therefore, the required grasping force is also unknown. the best control strategy to decide the grasping force value in a manner like the human brain does is the fuzzy control strategy that mimics the human reasoning way [6]. the proposed fuzzy control in this research consists of three membership functions shown in figure [4], the inputs (amount of sliding (s) in (cm) and the rate of sliding (δs) in (cm/sec)) that may be observed from the slide sensor [6] and one output (number of the mentioned parallel connected muscle wires that will be activated to generate the required grasping force). the rules of the fuzzy controller are designed as shown in table (1). from table (1) because the variables are fuzzy, each rule (which is common sense selected) will contribute to a different degree. the first step toward arriving at a single output value is to compute the compatibility for each rule [7]. where the compatibility is simply the product of the two probabilities in the rule (i.e. the influence of the rule): compatibility = wi = ai1 x ai2 i = 1, 2, 3, …. where; wi= the influence of the rule i ai1= probability of first condition (s) ai2= probability of second condition (δs) fig.3. robotics hand catching piece [6]. b. fbd of the robotics hand catching piece a. schematic of robotics hand catching piece w yarub omer naji al-azzawi al-khwarizmi engineering journal, vol. 7, no. 3, pp 13 18 (2011) 16 fig.4. the membership functions of the inputs and output. table 1, fuzzy rules δs s slow ok quick small 2 4 6 medium 4 6 8 large 6 8 10 for example take three case studies: 4. results and discussion case study 1: the slide s=0.125 cm and sliding rate δs = 0.625 cm/sec shown in figure [4], applying the compatibility to the applicable rules as following: w1= 0.75 x 0.75 = 0.5625 w2= 0.1875 w3= 0.1875 w4= 0.0625 now the output value for each applicable rule is: output = yi = wi x bi i = 1, 2, 3, .... where bi = appropriate value from the output table y1 = w1 x b1 = 0.5625 x 4 = 2.25 y2 = 1.125 y3 = 1.125 y4 = 0.5 now there are two outputs from the two rules, but it is needed to defuzzify this data into a single 1 2 3 4 5 6 7 8 9 10 output variable (number of activated muscles) 0.75 0.25 0.75 0.25 0.75 0.25 0.125 0.875 0.625 0.875 0 0.25 0.5 0.75 1 input variable " slide s (cm) " small medium large case1 case2 1 slow ok quick 0 0.25 0.5 0.75 1 input variable "sliding rate δs (cm/sec) " 1 yarub omer naji al-azzawi al-khwarizmi engineering journal, vol. 7, no. 3, pp 13 18 (2011) 17 command for the number of the selected activated muscle wires and this is as follows [7]: case study2: by increasing the amount of sliding say s = 0.875 cm with the same sliding rate δs = 0.625 cm/sec, and by applying the same strategy as the first case: w1= 0.1875 w2= 0.0625 w3= 0.5625 w4= 0.1875 and the output value for each applicable rule: y1 = 1.125 y2 = 0.5 y3 = 4.5 y4 = 1.625 the value of output (i.e. number of activated muscle wires) will be: case study3: the sliding s = 0.875 cm and increasing the sliding rate δs = 0.875 cm/sec. by applying the compatibility to the applicable rules as follows: w1= 0.0625 w2= 0.1875 w3= 0.1875 w4= 0.5625 the output value for each applicable rule is: y1 = 0.375 y2 = 1.5 y3 = 1.5 y4 = 5.625 the value of output (i.e. number of activated muscle wires) will be: it is clearly shown from the results that by applying the proposed fuzzy control strategy to the proposed robotics hand, the process looks like that of the human hand whereas the slipping or the slipping rate of the caught piece increases and then the number of the activated muscle wires will increase also to increase the amount of the catching force. this is what will happen when somebody needs to catch something he doesn’t know the amount of its weight or the coefficient of friction between the hand finger tips and the caught piece. 5. conclusion and recommendation the proposed control system with its easy way can simply mimics the human hand response from reducing the weight of the system and keeping away from the electrical noises and also the catching force can be developed in a small environment depending on the muscle wire specifications. so the whole system may be used effectively in many different applications like a robotic hand disassembling explosives or reaching different dangerous chemical parts without destroing them or slipping them down. it is also recommended in this work to design an effective sliding sensor that can measure the amount of sliding and at the same time the sliding rate. 6. references [1] pedram afshar and yoky matsuoka "neuralbased control of a robotic hand evidence for distinct muscle strategies" ieee 2004. [2] vishalini bundhoo and edward j. park “design of an artificial muscle actuated finger towards biomimetic prosthetic hands" ieee 2005. [3] megan grimm, a. antonio arroyo, michael nechyba " thing: a robotic hand with realistic thumb pronation" machine intelligence laboratory 2008. [4] roger g. gilbertson "muscle wires" project book 2003. [5] a.salam al-ammri, bahaa i. kadim, yarub o. al-azzawi "miniature two -fingered robot hand driven by muscle wires actuators" al-khwarizmi magazine 2008. [6] ra'ad kadim mohamed "pneumatic actuation and fuzzy control of robotics hand" al-kuffa magazine 2010. [7] christopher t. kilian “modern control technology, components and systems" delmar 2001. )2011( 13 18 ، صفحة3، العدد 7مجلة الخوارزمي الھندسیة المجلد یعرب عمر ناجي العزاوي 18 التحكم الضبابي بقوة مسك ید اإلنسان اآللي باستخدام مشغل األسالك العضلیة یعرب عمر ناجي العزاوي جامعة بغداد/ كلیة الھندسة الخوارزمي/ قسم ھندسة المیكاترونكس الخالصة بھا الھدف من ھذا البحث ھو السیطرة على مقدار قوة مسك ید االنسان اآللي باستخدام اسالك عضالت اصطناعیة كمشغل لتحقیق االستجابة المرغوب المالئم لقوة تم تحقیق االختیار. لید االنسان اآللي وذلك من اجل مسك اشیاء مختلفة بدون تحطیمھا او اسقاطھا باسلوب مشابھ لطریقة مسك الید البشریة . تم اقتراح الیة لترتیب االلیاف العضلیة االصطناعیة لتحقیق االختیار االفضل لمقدار قوة المسك. المسك من خالل المحاكات باستخدام تقنیة السیطرة الضبابیة یادة قوة المسك كلما زاد وزن القطعة الممسوكة بنفس لقد اوضحت النتائج امكانیة تطبیق استخدام ھذه التقنیة المقترحة والتي تحاكي تفكیر االنسان حیث یتم ز .مقدار الزیادة تقریبا dr. sadiq jaffar abass /al-khwarizmi engineering journal, vol.2, no. 1,pp 1-14 (2006) 1 al-khwarizmi engineering journal al-khwarizmi engineering journal, vol.2, no.1,pp 1-14, (2006) biomechanical aspects of shoulder and hip articulations: a comparison of two ball and socket joints dr. akram abood jaffar dr. sadiq jaffar abass mustafa qusay ismael department of human anatomy medical engineering department medical engineering department college of medicine college of engineering college of engineering al-nahrain university al-nahrain university al-nahrain university (received 6 march 2005; accepted 2 october 2005) abstract: the shoulder and hip joints though essentially both are ball and socket joints, show structural variability to serve functional needs. this study aims at revealing some of the structural and functional properties of each of the two joints regarding the factors that contribute to the stability of any joint in the body, namely: bone, ligament, and muscle. twenty dried scapula, hip, humerus, and femur were used. the area of the articular surfaces was estimated by molding a sheet of dental wax. using special graphics software, a novel procedure was described to calculate the area under the curve, which was postulated to indicate the degree of curvature. tension test was applied using a testometric machine, which was locally modified to suit biological specimens. a finite element analysis was designed to study the articulating bones under different loading conditions. in the hip joint, the area of the articular surface of the head of the femur and that of the lunate showed no significant statistical difference. for the shoulder joint, the articular areas of the head of the humerus and the glenoid were statistically different. no statistical significance was observed regarding curvature of the articular surfaces within both the hip and shoulder joints; however, the values were significantly different between the hip and shoulder. in the tension test, the site of rupture of the capsule of the shoulder joint was found to be at its anteroinferior part. the more contact between the area of the cup and ball, as was demonstrated in the hip joint, the more stable the joint. on the contrary, the shoulder articular surfaces have less area of contact, which makes it more mobile and decreases stability. the insignificant difference in curvature within both joints indicates a good congruity and thus more stability especially during joint movement. the curvature difference between the head of femur and the head of humerus indicates that the range of motion is quite different for the two joints. results obtained from the finite element analysis were important in understanding the areas of stress concentration and were thoroughly explained from the anatomical point of view and linked to muscle and joint capsule attachments. the model of the joints developed in this study can be used as a computational tool to joint biomechanics and to prosthetic implant analysis. keywords: hip joint, shoulder joint, finite element analysis, biomechanics. dr. sadiq jaffar abass /al-khwarizmi engineering journal, vol.2, no. 1,pp 1-14 (2006) 2 1.introduction the shoulder and hip joints are synovial joints of the ball and socket variety, each is formed of a ball–like convex surface being fitted into a concave socket. both joints have three degrees of freedom of motion: flexion-extension, abduction-adduction, and rotation. each joint has a capsule and several associated ligaments. the bones articulating in the shoulder joint are the head of the humerus and the glenoid cavity of the scapula; in the hip joint, the articulating bones are the head of the femur and the lunate surface of the acetabulum of the hip bonei,ii. functionally, the hip joint provides stability in addition to providing mobility; whereas the shoulder provides primarily mobility. the hip joint supports the weight of the head, upper extremities, and trunk in the erect posture. it also provides a pathway for the transmission of forces from the pelvis to the lower extremity and from the lower extremity to the pelvis. structurally, the pelvis is relatively rigid unitary structure, compared with the freely moveable, independent structure of the scapulaii. thus, these two joints though essentially both are ball and socket joints but they bear structural variability to sub serve functional needs. the hip and shoulder articulations were the subject of extensive biomechanical studies using a variety of methodsiii,iv,v,vi,vii. in this study, the shoulder and hip joints will be compared for some structural and functional properties pertaining to bone, ligament, and muscle; the triad that control joint stability. studying the areas and curvatures of the articular surfaces should reveal some architectural properties pertaining to their stability and range of motion. tension test would help to unfold some mechanical properties of the joint capsule and associated ligaments. finite element analysis (fea) would help to reveal tension and stress pathways across the joints. fea is one of the modern methods of human joint stress analysisviii,ix,x,xi. the aim of the finite element analysis is to develop a three-dimensional model of the joints that can be used as a computational tool to joint biomechanics and to prosthetic implant analysis. 2.materials and methods a series of 20 isolated dried scapula, hip, humerus, and femur were used from the inventory of the college of medicine/ al-nahrian university. the bones belong to adults of the caucasoid race regardless of gender. measurement of the area of the articular surfaces the areas of the smooth articular surface of the head of the humerus, glenoid cavity of the scapula, the head of the femur, and the lunate surface of the acetabulum of the hip bone, which in life would have been covered by articular cartilage were estimated using a molding technique. a sheet of dental wax was warmed gently until just pliable, molded to the contours of the articular surfaces, and trimmed exactly around the articular margins. the trimmed piece was weighed along with a reference piece of wax sheet of known area. the surface area of the molded wax was calculated from these valuesxii. the curvature of the articular surfaces each of the heads of the humerus and femur was digitally scanned using a flat bed scanner. on the scanned profiles, 20-36 points were allocated on the circumference. the curvatures of glenoid cavity and lunate surface were treated by inserting an amount of children clay into the socket, pressed until it took the shape of the socket. the molded clay piece was then processed in a similar manner as indicated for the joint ball. using circumference points, a curve was drawn by a turbo grapher program (turbographer 32bit, version 2.135 copyright ©1996-1999, jeffrey r. radue ,p.e) from which the area under the curve was calculated. dr. sadiq jaffar abass /al-khwarizmi engineering journal, vol.2, no. 1,pp 1-14 (2006) 3 tension test a testometric machine (testometric co. ltd., england), at the college of engineering/ department of medical engineering/ al-nahrain university, was employed. the machine is originally devised for testing the mechanical properties of materials such as tension, compression, and bending. in this study, hooks and metal holders were designed to modify the machine so that it will be suitable for testing biological material (fig.1). two fresh sheep shoulder joints were used to standardize the machine. two adult, male, formalin-fixed human shoulder joints were denuded from their muscles with care taken not to disrupt the capsule. the human joints were provided from the teaching material used at the college of medicine/ al-nahrain university. tension was applied on the joints to measure the amount of force required before the joint capsule is torn. 3.fea study using ansys 5.4 the bones that were used for model geometry were cut into slices and drawn on a graph paper from which key points were determined. these points were used to make a closed curve which represents the section plane circumference then converting this curve into area. relations between section planes give the final volume which represents the model. after the creation of the model, it was meshed to be ready for force application and stress analysis. regarding the hip bone, the model used by jaffar et al.xiii was employed. isotropic material properties were used follows: σyield = 85, σultimate =120, e=18000 (mpa). the weight was regarded as a boundary condition. segment weights expressed in percentage of total body weight.were usedxiv. the applied load was represented by the force of muscles and ligaments attached to the bones. these forces were calculated using the basic equation of moment equilibrium (σmp=0), where p is the center of rotation. by finding the distance between the center of rotation of each bone and the point of force action, the approximate values of muscle and ligament forces were found. the major muscles, ligaments and reaction forces acting on the bonesxv,xiv,xvi were calculated for their forces. for each model, the applied forces were supposing three body weights: 70kg, 90kg, and 110kg (tables 1-4). 4.results area of the articular surfaces: in the hip joint, the mean area of the articular surface of the head of the femur was 29.8±1.23cm2, the mean area of the lunate surface was 24.8±0.75cm2. in the shoulder joint, the mean area of the articular surface of the head of the humerus was19.0±0.88cm2 and the mean area of the glenoid cavity was 5.40±0.30cm2. the difference in the mean areas was statistically significant in the shoulder joint (t-test, p<0.01). curvature of the articular surfaces the means of area under the curve of the articular surfaces of the head of the femur, lunate surface, head of the humerus, and glenoid cavity were 140.0±5.837, 141.0±6.505, 87.9±3.488, and 85.9±1.453 unit area respectively. significant statistical difference existed between the means of the area under the curve of the two joints, while the same parameter did not vary between the ball and socket within the same joint (t-test, p<0.01). tension test the testometric machine worked successfully with the sheep material and was standardized accordingly. in the fixed human joints, increasing the tensile force resulted in broken bones before the joint capsule was completely torn. the maximum force reached before the test was stopped was 850n (fig.2), at this point, however, the shoulder joint dr. sadiq jaffar abass /al-khwarizmi engineering journal, vol.2, no. 1,pp 1-14 (2006) 4 capsule was partially torn at its anteroinferior part. because of bone fragility, the test was not extended for a human hip joint since no human fresh material could be provided. 5.models analysis the results of the fea were represented as a contour and as von mises stresses. the color contours represent the range of the stresses, from the blue (low value) to the red (high value). the area with red color is the area at which the stress is in its maximum value and it is the first probable region to fail when the joint is loaded with very high loads. figures 3-5 show the color contours of von mises stresses when supposing that 90kg body weight material was used. for the scapula (fig.3), the stress concentration was in the spine, scapular notch close to the neck, superior angle and the superior part of the medial border. the stress in these regions increased with the increase of the body weight. analysis of the scapula for the 90kg and 110kg body weight, revealed that another region of stress concentration could be noted, this was represented by a beam of stresses radiating from the superior-medial aspect toward the inferio-lateral border of the scapula, adding some stresses in the neck and around the glenoid cavity. in the humerus (fig.4), the regions that revealed high stresses were the greater tubercle and the surgical neck. the stresses inside the upper end of the humerus if compared with that of the scapula were small. regarding the acetabulum, and by using the model of jaffar et al.xiii the largest values of stresses for 70kg person were distributed in its anterior and posterior borders. by increasing the load, it was noticed that stresses would be concentrated in the superior part of the acetabulum. in the femur (fig.5), the stresses were concentrated at the upper part of the head and neighboring part of the neck at all loading conditions. a line of high stress can also be noted at the lower margin of the neck. the neck of the femur, however, demonstrated higher stresses than the lower part of the head and the regions of the greater and lesser trochanters. the stresses of the upper end of the femur were higher than those recorded for the scapula or the upper end of the humerus. 6.discussion factors that contribute to the stability of any joint in the body are bone, ligament, and muscleii. in this study, the role of the bony articular surfaces in maintaining joint stability was studied measuring the area of the articular surfaces and calculating the degree of curvature. areas and curvatures the wax technique method used to measure the area of articular surfaces was simple and required no expensive equipment; it could be applied particularly to the area measurement of highly curved articular surfaces. the mean of the areas of articular surfaces of the hip joint did not differ significantly, while the difference was statistically significant for the shoulder joint. the difference in areas of the articulating surfaces gives an indication of the degree of compatibility of the ball with its socket. the ratio of the area of articulation of the femur to the lunate was (1.2:1). for the shoulder joint, the ratio of the area of articulation of the humerus to the glenoid of the scapula was (3.5:1). the ratio between the areas of each ball with its socket was comparable with that of the other researchersxv. the more contact between cup and ball, the more stable the joint is. from the above-mentioned ratios, the hip is more stable than the shoulder joint. the greater mobility of the shoulder increases instability and the risk of dislocation. dr. sadiq jaffar abass /al-khwarizmi engineering journal, vol.2, no. 1,pp 1-14 (2006) 5 another parameter that plays a role in joint stability pertaining to the bony factor is the curvature of articular surfaces. it is difficult to measure the curvature of the articulating surfaces and there was no applicable nor a standard method to measure it in biological specimens. thus, a simple yet applicable method was used in this study to find a value that represents the curvature; that is the area under the curve. the effect of curvature – as a parameter or property – indicates the degree of congruity of the articular surfaces of a joint. in this study, where there was no significant difference in curvature within both joints, it can be concluded that there was a good congruity of the joint articular surfaces. congruity implies more stability especially during joint movement. the effect of congruity of joint surface has a less profound significance in static state. the significant difference in curvature between the two balls (the head of hip and the head of humerus) and between the two sockets (glenoid cavity and the lunate surface) indicates that the range of motion is quite different for the two joints. it should be emphasized that the results of this study does not take into account the shape and thickness of the articular cartilage nor the presence of the fibrocartilagenous labrum that surrounds the socket of both joints. tension test the modifications applied to the testometeric machine in this study (hooks and metal plates) were suitable for joint installation as has been proved by the pilot study on the sheep joint. however, formalin fixed human bone could not withstand the forces applied. formalin fixation changes the tensile properties of collagen and renders the bone weaker and easy to be brokenxvii. it is recommended that the modified machine be used on fresh tissue. since no fresh human hip joint could be afforded then the test was not extended to the hip joint. future studies on the modified machine can implement fresh animal joint when no human material can be provided. in spite of the bone failure when testing the human shoulder joint, the force which was applied before failure was 43% of the desired force and the curve obtained was comparable to the curve of kaltsas in shoulder jointxviii. the site of rupture of capsule of the shoulder joint was at its anteroinferior part suggesting that this part of the capsule is the weakest. this corresponds to the finding that anterior dislocation of the shoulder is the most common as is always mentioned in literaturexix,xx. fea models in the scapula where the stress which was concentrated in the scapular spine and the region of scapular notch close to the neck can be attributed to the tensile force applied from the upper fibers of trapezius muscle. in the superior angle and the superior part of the medial border of the scapula, the effect of the levator scapula and rhomboid minor was the major force which causes the reactions and stresses in this region. the stresses in the neck of the scapula and around the glenoid cavity for the 90kg and 110kg body weight analyses, can be attributed to the reaction between the upper medial border at which the upper trapezius and the levator scapula muscles try to elevate the scapula upward, and the infero-lateral border at which the load applied is represented by the weight of the upper limb which pulls the scapula inferiorly. in the greater tubercle of the humerus, the high stress can be viewed as a translation to the effect of the force of the joint capsule and the coracohumeral ligament, but above all, to the rotator cuff muscles. these muscles stabilize the joint by pressing the head into the glenoid. three of the dr. sadiq jaffar abass /al-khwarizmi engineering journal, vol.2, no. 1,pp 1-14 (2006) 6 four rotator cuff muscles (namely, supraspinatus, infraspinatus, and teres minor) are attached to the greater tubercle very close to the attachment of the capsule of the shoulder joint for which they provide reinforcementsxxi. at the surgical neck of the humerus (the narrow region between the proximal end and the shaft of the humerus, which is the most likely region to be fractured in the upper part of the humerusxxii), stress concentration reflected an internal interaction between the loads applied on the humerus (represented by the weight of the rest of the humerus plus the weight of the forearm and hand) and the reaction force on the articular surface of the humerus, the tension force of the joint capsule, and rotator cuff muscles. the small stresses inside the upper end of the humerus when compared with that of the scapula might be attributed to thinness of the latter bone. however, the fact that only the proximal end of the humerus was analyzed in this study should not be overlooked. the forces that suspend the humerus are not only concentrated at its proximal end, but there are other powerful muscles that suspend the humerus yet they have a more distal insertion. these muscles are the coracobrachialis and deltoid, which are attached to the middle of the shaft of the humerus (a region which was not included in this study). moreover, biceps brachii, another muscle suspending the upper limbs in the static position, is not attached to the humerus but to the more distal radius. the long head of triceps, which extends from the scapula to the ulna, suspends the limbs at a more distal position than the humerusxxi. the intact acetabulum is a horseshoe form that wraps around the superior, anterior, and posterior aspects of the femoral head. in the lightly loaded state for the 70kg, the dome of the acetabulum is relatively unloaded, and the stress is transferred between the femoral head and the acetabulum through the anterior and posterior extensions of the horseshoeiii. when the load was progressively increased (for the 90kg and the 110kg body weight) and since the acetabulum is not in continuity inferiorly, the stresses will be distributed superiorly and the anterior and posterior sides of the horseshoe are free to expand so that a more congruous seating of the femoral head is allowed. this phenomenon of deformation under load leads to increasing congruity with progressive loading. in the femur, where stresses higher than the humerus and scapula were recorded, this is coexistent with the fact that the weight-bearing femur is subjected to higher force if compared with the applied load on the humerus and scapula. the concentration of the stress at the upper part of the head is consistent with the finding that pressure distribution in the articular cartilage is mainly concentrated in its anterosuperior surface when using pressure-sensitive filmiii. the concentration of these stresses at the neck of the femur even in the slightly loaded state explains the predilection of the neck to undergo fracture. in older subjects, femoral neck fractures, which are common, might take place even after mirror trippingxxii. the line of high stress at the lower margin of the neck is compensated in life by the calcar femorale, a flange of compact bone projecting like a spur into the cancellous bone of the neck and adjoining shaft from the concavity of their junctionxxiii. dr. sadiq jaffar abass /al-khwarizmi engineering journal, vol.2, no. 1,pp 1-14 (2006) 7 body weight (kg) weight of arm, forearm and hand (n) upper trapezius (n) levator scapulae (n) rhomboids (n) 70 39.6 44.5 34.6 19.8 90 50.9 57.3 44.5 25.4 110 62.2 69.9 54.4 31 table (1) calculated forces acting on the scapula body weight (kg) weight of forearm & hand (n) coracohumeral ligament force (n) reaction force (n) 70 28.5 12.2 4 90 36.6 15.7 5.2 110 44.7 19.1 6.4 table (2) calculated forces acting on the humerus body weight (kg) 1/3 of b.w (n) abductor muscles (n) reaction of ground (n) 70 228.7 22.9 68.6 90 294 29.4 88.2 110 359.3 35.9 107.8 table (3) calculated forces acting on the femur body weight (kg) 1/6 of b.w (n) 1/3 of b.w (n) force of sacrotuberous ligament. (n) 70 114.4 228.7 63 90 147 294 81 110 179.7 359.3 99 table (4) calculated forces acting on the hip bone dr. sadiq jaffar abass /al-khwarizmi engineering journal, vol.2, no. 1,pp 1-14 (2006) 8 fig.1: reinforced human shoulder joint specimen positioned on the testometric machine. note the metal plate and hooks used to fix and reinforce the specimen. 0 20 30 55 90 155 250 360 476 600 750 800 850 800 340330315 240 260 230230 175170168 100 50 00 100 200 300 400 500 600 700 800 900 strain (%) s tr e s s (n ) fig.2: tension test curve of fixed human shoulder joint. testometric machine output curve. dr. sadiq jaffar abass /al-khwarizmi engineering journal, vol.2, no. 1,pp 1-14 (2006) 9 fig.3: von mises stresses for 90kg body weight of the posterior surface of the scapula. fig.4: von mises stresses for 90kg body weight of the posterior surface of the humerus. dr. sadiq jaffar abass /al-khwarizmi engineering journal, vol.2, no. 1,pp 1-14 (2006) 11 fig.5: von mises stresses for 90kg body weight of the posterior surface of the femur. dr. sadiq jaffar abass /al-khwarizmi engineering journal, vol.2, no. 1,pp 1-14 (2006) 11 references i sarrafian sk: gross and functional anatomy of the shoulder. clinical orthopedics and related research. 1983; 173:11-19 ii sinnatamby cs: last’s anatomy. 10th ed. churchill livingstone. edinburgh. 1999; pp:45-48,123-126 iii afoke nyp, byers pd, and hutton wc: contact pressures in the human hip joint. j. bone joint surg. 1987; 69-b:536-541 iv bergmann g, deuretzbacher g, heller m, graichen f, rohlmann a, strauss j, and duda gn: hip contact forces and gait patterns from routine activities. j biomech. 2001; 34:859-871 v hewitt jd, glisson rr, guilak f, and parker vt: the mechanical properties of the human hip capsule ligaments. j. arthroplasty. 2002; 28-89. vi kelkar r, wang vm, flatow el, newton pm, ateshian ga, bigliani lu, pawluk rj, and mow vc: glenohumeral mechanics: a study of articular geometry, contact, and kinematics. j shoulder elbow surg. 2001; 10:73-84. vii thalamann nm kang mj, goto t: problems and solutions for the accurate 3d functional modeling of the hip and shoulder. proc. of ieee computer graphics international. 2002; [www.miralab.unige.ch/papers/135.pdf] vii sarrafian sk: gross and functional anatomy of the shoulder. clinical orthopedics and related research. 1983; 173:11-19 vii sinnatamby cs: last’s anatomy. 10th ed. churchill livingstone. edinburgh. 1999; pp:45-48,123-126 vii afoke nyp, byers pd, and hutton wc: contact pressures in the human hip joint. j. bone joint surg. 1987; 69-b:536-541 vii bergmann g, deuretzbacher g, heller m, graichen f, rohlmann a, strauss j, and duda gn: hip contact forces and gait patterns from routine activities. j biomech. 2001; 34:859-871 vii hewitt jd, glisson rr, guilak f, and parker vt: the mechanical properties of the human hip capsule ligaments. j. arthroplasty. 2002; 28-89. vii kelkar r, wang vm, flatow el, newton pm, ateshian ga, bigliani lu, pawluk rj, and mow vc: glenohumeral mechanics: a study of articular geometry, contact, and kinematics. j shoulder elbow surg. 2001; 10:73-84. vii thalamann nm kang mj, goto t: problems and solutions for the accurate 3d functional modeling of the hip and shoulder. proc. of ieee computer graphics international. 2002; [www.miralab.unige.ch/papers/135.pdf] dr. sadiq jaffar abass /al-khwarizmi engineering journal, vol.2, no. 1,pp 1-14 (2006) 12 vii buechler p, ramaniraka na, farron a and rakotomanana lr: hemiarthroplasty in human shoulder: a finite element analysis. in computer methods in biomechanics and biomedical engineering-3, middelton j et al, ed. g and breach, 2001. 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[www.trigenterprises.com/pcoms/ go.php?id=ahr0cdovl2zlc3d3dy5mzxmuy3dyds5lzhuvyxjjagl2zs9pc2cvchjvy2vlzglu z] vii majumder s, roychowdhury a, and pal s: variations of stress in pelvic bone during normal walking considering all active muscles. trends biomater. artif. organs. 2004; 17:48-53 vii parma h., gilmore c., and palfrey a. j.: the area of articular surface of the distal end of the femur. j. anat. 1988; 157:233-234. vii jaffar aa, abbas sj & abdullah hm: stress analysis of the hip bone. al-khwarizmi engineering journal. 2005; 1:61-72 vii susan hj: basic biomechanics. 2nd ed., mcgraw-hill. 1995; pp. 171-182, 208-219. vii norkin cc and levangie pk.: joint structure and function. 3rd ed. f.a. davis company. philadelphia. 1984; pp.157-178, 255-286. vii bergmann g, graichen f, rohlmann a, and linke h: hip joint forces during load carrying. clin orthop relat res. 1997; 335:190-201 vii currey jd. brear k. zioupos p. reilly gc., effect of formaldehyde fixation on some mechanical properties of bovine bone. biomaterials. 1995; 16:1267-1271 vii kaltsas ds: comparative study of the properties of the shoulder joint capsule with those of other joint capsules. clinical orthopedics and related research. 1983; 173:20-26 vii reeves b: experimetns in tensile strength of the anteriorcapsular structures of the shoulder in man. j. bone joint surg. 1968; 50b:859 vii dowson d and wright v: introduction of the biomechanics of joints and joint replacement. mechanical engineering publications. london. 1981 dr. sadiq jaffar abass /al-khwarizmi engineering journal, vol.2, no. 1,pp 1-14 (2006) 13 vii moore kl and dalley af: clinically oriented anatomy. 5th ed. lippincott williams & wilkins. philadelphia. 2006. pp:853-859. vii solomon l, warwick dj, and nayagam s: apley’s system of orthopedics and fractures. 8th ed. arnold. london. 2001. pp:591-592, 684-690. vii last rj: anatomy regional and applied. 6th ed. churchill livingstone. edinburgh. 1978. pp:197. dr. sadiq jaffar abass /al-khwarizmi engineering journal, vol.2, no. 1,pp 1-14 (2006) 14 جوانب ميكانيكية احيائية لتمفصالت الكتف والورك: مقارنة لمفصلين من نوع الكرة والتجويف مصطفى قصي اسماعيل د.صادق جعفر عباس د.أكرم عبود جعفر / كلية الطب قسم الهندسة الطبية / كلية الهندسة قسم الهندسة الطبية / كلية الهندسة قسم التشريح جامعة النهرين جامعة النهرين جامعة النهرين :الخالصة رغم ان مفصلي الكتف والورك ينتميان اساساً الى نوع المفاصل ذات الكرة والتجويف اال انهما يظهران تباينات تركيبية لخدمة المتطلبات الوظيفية. تترافق هذه االختالفات التركيبية بين المفصلين ضرورة مع الخواص الميكانيكية التابعة ألي منهما.بال تهدف هذه الدراسة الى الكشف عن بعض الخواص الميكانيكية والوظيفية لكل من مفصلي الورك والكتف. حيث تم سبر الخواص الهندسية التصميمية لسطوح التمفصالت العظمية من خالل دراسة مساحة الجهاد للكشف عن بعض الخواص الميكانيكية لمحافظ المفاصل وتقوس هذه السطوح. كما تم استخدام فحص ا لغرض تحليل العناصر المحددة الظهار مسارات الشد والضغط واالربطة المرافقة لها. كما تم استخدام نموذج عبر المفصلين. تم استخدام عشرين عظم جاف من كل من لوح الكتف، الحوض، العضد، والفخذ. وتم حساب اب المساحة تحت باستخدام قالب من شمع االسنان. كما تم وصف طريقة مبتكرة الحتس مساحات التمفصل التقوس عن طريق استخدام برامجية خاصة للتعامل مع الرسوم. ونعتقد بأن هذه الطريقة يمكن ان توفر مؤشر لدرجة التقوس. كما التجأنا الى تحوير جهاز فحص االجهاد محلياً ليتالئم مع فحوصات النماذج قطيع العظام الى شرائح وتحويلها الى صور البايولوجية. اما دراسة تحليل العناصر المحددة فقد صممت بعد ت تحت تأثير قوى مختلفة. ansysرقمية ثالثية االبعاد ليتم تحليلها بواسطة برنامج اظهرت النتائج في مفصل الورك بأن مساحة السطوح التمفصلية لرأس عظم الفخذ والسطح الهاللي تتابع(. اما بالنسبة لمفصل الكتف، فأن بال 8سم 0،،5±2،،8و 8سم 3،81±2،،8لم تكن مختلفة احصائيا ) و 8سم 5،22±5،،3السطوح التمفصلية لرأس عظم العضد والجوف الحقاني اظهرت اختالفا احصائيا ) بالتتابع(. 8سم ±5،1،،0 ،0،2±3،5،5كانت المساحة تحت التقوس للسطح التمفصلي لرأس عظم الفخذ والسطح الهاللي بع. اما في مفصل الكتف فقد كانت القيم لراس عظم العضد والجوف وحدة مساحة بالتتا 1،03±3،3،5و لم تالحظ فروق احصائية مهمة ضمن وحدة مساحة بالتتابع. 0،،3±20،3و ،،،1±،،،2الحقاني مفصلي الورك والكتف، في حين كانت الفروق مهمة احصائياً عند المقارنة بين سطوح المفصلين. تطبيق فحص االجهاد وذلك لجعل اآللة المستخدمة اكثر مالئمة تمت مناقشة الصعوبات التي واجهت للفحوص البايولوجية في المستقبل. ورغم الصعوبات اال ان النتائج اظهرت بأن موقع تمزق محفظة مفصل الكتف كانت عند الجهة االمامية السفلى. عل المفصل اكثر ان وجود تماس كبير بين مساحة الكرة والتجويف، كما ظهر في مفصل الورك، يج استقراراً. على العكس من ذلك، فان مساحة التماس للسطوح التمفصلية لمفصل الكتف كانت اقل بكثير مما يقلل من ثبات المفصل. ان عدم وجود فروق مهمة لتحدب السطوح التمفصلية ضمن مفصلي الكتف والورك يشير الى جودة لمفصل. اما اختالف التحدب بين المفصلين فانه يشير الى التطابق وبالتالي ثباتاً اكبر خاصة عند حركة ا اختالف مديات الحركة بينهما. كانت النتائج التي تم التوصل اليها من خالل تحليل العناصر المحددة مهمة في تحديد مناطق تمركز االجهادات . ان نماذج وقد تم تفسيرها من وجهة نظر تشريحية وربطها بمناطق اتصال العضالت ومحفظة المفصل المفاصل التي طورت في هذه الدراسة يمكن ان تستخدم كوسيلة حساب للميكانيك االحيائي للمفاصل وفي تحليل المفاصل الصناعية المغروسة. الميكانيكا البيولوجية ،المحددةتحليل العناصر مفصل الورك، مفصل الكتف، مفتاح الكلمات: علي هاشم al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 8, no.4, pp 96 105 (2012) field programmable gate array (fpga) model of intelligent traffic light system with saving power ali hashim jryian department of mechanics /institute of technologybaghdad e-mail: aadd_ssd@yahoo.com (received 14 march 2012; accepted 6 september 2012) abstract in this paper, a fpga model of intelligent traffic light system with power saving was built. the intelligent traffic light system consists of sensors placed on the side's ends of the intersection to sense the presence or absence of vehicles. this system reduces the waiting time when the traffic light is red, through the transition from traffic light state to the other state, when the first state spends a lot of time, because there are no more vehicles. the proposed system is built using vhdl, simulated using xilinx ise 9.2i package, and implemented using spartan-3a xc3s700a fpga kit. implementation and simulation behavioral model results show that the proposed intelligent traffic light system model satisfies the specified operational requirements. keywords: intelligent traffic light system, intelligent traffic light controllers, traffic light algorithm, fpga, xilinx ise 9.2i. 1. introduction travel became very difficult between the places of the city because of traffic jams. traffic jams are a major problem in many modern cities around the world. when populations increase, the number of cars is increasing. therefore, traffic congestion is growing. traffic jams lead to a loss of time for people, the loss of opportunity, and nervous tension. most traffic light controllers are fixed-cycle controllers, in which all alternative traffic light settings get a particular time-interval for being green. [1] in the fixed time traffic light control system, cannot get the optimal solution for the traffic congestion. this leads to using other systems. one of these systems is an intelligent traffic light system. [2] most of the traffic light systems operate depending on the specific time for each specific light. an intelligent traffic light system senses the presence or absence of vehicles and reacts accordingly. the idea behind the intelligent traffic systems is to reduce unnecessary waiting time for drivers when the light is red. the intelligent traffic system detecting the presence or absence of vehicles, determines the time required for each side. there are several ways to detect the presence of vehicles on the roads. [3-4] a different approach based on applying intelligent traffic systems in order to manage traffic flow in a more effective and efficient manner is needed. [5-6] sensor is a crucial element in an intelligent traffic control. the most common sensor is inductive loop. it is very common in vehicle actuated system to detect vehicle presence. it is also very common in an urban traffic control system to count the number or to measure headway of approaching vehicles. another type of sensor is video detection system. this system is very flexible and able to carry out traffic count and measure queue length accurately. [5-7] recently, fpgas have been seen to support real-time network traffic measurements [8]. the fpga is a suitable platform for accelerating scientific computations. fpgas are a good alternative to application specific integrated circuits (asics) for high speed embedded mpc mailto:aadd_ssd@yahoo.com ali hashim jryian al-khwarizmi engineering journal, vol. 8, no.4, pp 96 -105(2012) 97 applications since they offer much reduced lowvolume cost, greater flexibility, and a shorter design cycle, reducing the risk while still maintaining deterministic execution time and high power efficiency [9]. the aim of this paper is to design a new approach of intelligent traffic light system with saving power based on fpga. this system operates according to the number of vehicles on each side of the intersection instead of using a fixed time for each traffic light (green, yellow, and red). so this system will work like a traffic cop when governing the passage of vehicles. therefore, it will reduce the waiting time. 2. the proposed intelligent traffic light system the proposed intelligent traffic light system consists of sensors placed on each side ends of the intersection. these sensors are sensitive to the presence or absence of vehicles. the sensors are responsible for the account of vehicles entering the road, as well as outside of it, hence the number of vehicles on each side calculated by the fpga ic according to equation (1). it is possible to use any type of sensors. cn=cinn-coutn …(1) whre cn is the number of vehicles on side n. cinn is the number of vehicles entering th side n. coutn is the number of vehicles coming out of side n. so when cn is equal to zero; it means that side n is empty. for the sub-street, the sensors placed at the end with the main street (each side of intersection represents main street). these sensors are connected with the main sensors of the main street. thus, any vehicle moving out of the substreet to the main street will be calculated as if it entered the main street through the main sensor itself. in other words, the counter of this side will be increment. furthermore, in the case of vehicles coming out of the main street to the sub-street; the counter will be decrement. figure (1) illustrates the mechanism of the development of the sensors on both ends of each side of the intersection. the proposed system works with nine states as shown in table (1). as observed in state 0 all lights are switched off, which represents the power saving state. power saving occurs when the lights of traffic are switched off so no power is consumed thus it depends on the absence of vehicles in the intersection. the other states represent the normal operation of the traffic light system. in this system, the transition from one state to another is not sequential. if the sensor detects the absence of vehicles on the sides of the intersection, the lights will be switched off (state 0). table 1, states of intelligent traffic light system. state state description traffic 1 traffic 2 traffic 3 traffic 4 0 power save off off off off 1 traffic 1 green green red red red 2 traffic 1 yellow yellow red red red 3 traffic 2 green red green red red 4 traffic 2 yellow red yellow red red 5 traffic 3 green red red green red 6 traffic 3 yellow red red yellow red 7 traffic 4 green red red red green 8 traffic 4 yellow red red red yellow ali hashim jryian al-khwarizmi engineering journal, vol. 8, no.4, pp 96 -105(2012) 98 fpga ic cout cin side 1 side 2 side 3 side 4 output sensor input sensor fig. 1. mechanism of sensors on both ends of each side of the intersection. this system is also a transition from state to state depending on the presence of vehicles on the road. in the absence of vehicles on a specific side, this side will be neglected (the green light does not work). in the event that the green light was on and all vehicles passed, the system will go to the other state without going through the yellow light state. if one side of the intersection has many vehicles and too 60 seconds passied (including yellow light state), the system will go to the other state, to prevent a long wait on the other sides of the intersection. transition to another state does not occur if one side is filled with vehicles and the other sides. are empty. all these conditions lead to reduce waiting time at the intersection when the red light was on. in case of vehicle failure on one side of the intersection, this side will take its normal passing time of 60 seconds before turning to the next, because the counter on this side did not specify that this side was empty. the operations of the proposed model are demonstrated in the flowchart shown in figure (2). fig. 2. the flowchart of the proposed traffic light. 3. fpga model of intelligent traffic light system the fpga model of intelligent traffic light system is built using vhdl (very high speed hardware description language), and implemented and simulated using xilinx ise 9.2i package. this model consists of two parts, entity declaration and process. the entity declaration ali hashim jryian al-khwarizmi engineering journal, vol. 8, no.4, pp 96 -105(2012) 99 part, shown in figure (3), is used to declare the signals of the intelligent traffic light system. the process part will be responsible for the processing traffic light system signals under the conditions described previously, and control the illuminations of traffic light according to system state. figure (4) shows the intelligent traffic light signals; the input signals (cin1, cin2, cin3, and cin4) represent the car input that is received by the signal the sensor to indicate that the vehicle entered that side of intersection. car output (cout1, cout2, cout3, and cout4); its input signals coming from a sensor as an indicator that the vehicle coming out of the intersection. the lights of the traffic light system are controlled by the output signals (r1, y1, g1, r2, y2, g2, r3, y3, g3, r4, y4, and g4). the simulation behavioral model test results of the intelligent traffic light system are shown in figures (5 to 8). as illustrated in figure (5) when a vehicle entered a specific side and the other sides of the intersection were empty, the green light of this side will be illuminated directly to facilitate the passage of the vehicle without waiting. if one side completed the passage of all the vehicles that were on it, the system will go to the other state without going through a yellow light state, as cleared in figure (6). figure (7) indicates that the system does not pass to any other state if one side of the intersection is of vehicles and the other sides are empty. as shown in figure (8), if one side of the intersection ha exceeded the time desired, it will transmit to the yellow light state and then to the other state depending on the presence of vehicles on other sides. as noted in the figures (5 to 8) the saving power state is clear, occurs when all sides of the intersection are empty. figure (9) illustrates the implementation of the proposed model where a prototype of traffic lights system was used. a push-bottom sensor is placed on the sides ends to detect the absence and the presence of vehicles; therefore sends it the signals to the spartan-3a xc3s700a fpga kit. the kit will count the number of vehicles depending on equation (1) and activate each side according to suitable state. the number of vehicles can pass in a specific side through a one period when the other sides are empty as shown in figure (10). as noted, the number of vehicles in the fixed-time system remains constant, while the number of vehicles triples when using the proposed system. figure (11) shows the number of vehicles that can pass in a specific side compared to the available vehicles in other sides. as observed, it is possible to pass 240 vehicles on one side, if the other sides are empty in case of using the proposed model, while it does not exceed 60 vehicles when using the fixed-time system. there are many avails of using the proposed model over the other traffic lights systems; it is easy maintenance because it uses one ic, unlike some systems that use more components [1]. the proposed system depends on a simple algorithms and equations while other system based on complicate algorithms like jade [3] and fuzzy logic [4]. moreover, most of other systems use computer to control them traffic lights and this make it more liable to be exposed to hacking and system errors [2,6]. also, it uses any type of sensors, unlike some other systems that require specific types of sensors. fig. 3. the entity source code declaration. entity itl is port(clock:in std_logic; cin1:in std_logic; cout1:in std_logic; cin2:in std_logic; cout2:in std_logic; cin3:in std_logic; cout3:in std_logic; cin4:in std_logic; cout4:in std_logic; r1:out std_logic; y1:out std_logic; g1:out std_logic; r2:out std_logic; y2:out std_logic; g2:out std_logic; r3:out std_logic; y3:out std_logic; g3:out std_logic; r4:out std_logic; y4:out std_logic; g4:out std_logic ); end itl; ali hashim jryian al-khwarizmi engineering journal, vol. 8, no.4, pp 96 -105(2012) 100 fig. 4. intelligent traffic light signals. fig. 5. simulation behavioral model when one side has vehicles and others are empty. ali hashim jryian al-khwarizmi engineering journal, vol. 8, no.4, pp 96 -105(2012) 101 fig.6. simulation behavioral model when one side had completed passage of all vehicles and the others have vehicles. fig. 7. simulation behavioral model when one side is full and others is empty. ali hashim jryian al-khwarizmi engineering journal, vol. 8, no.4, pp 96 -105(2012) 102 fig. 8. simulation behavioral model when one side is full and exceeds the time desired. fig.9. the proposed model implementation using the spartan-3a xc3s700a fpga kit. ali hashim jryian al-khwarizmi engineering journal, vol. 8, no.4, pp 96 -105(2012) 103 0 50 100 150 200 250 0 50 100 150 200 250 one period time v eh ic le s p as s in o ne s id e propsed traffic fixed-time traffic fig. 10. the number of vehicles passed in one side through a one period when the other sides are empty. 0 20 40 60 80 100 120 140 160 180 0 50 100 150 200 250 vehicles in other sides v eh ic le s p as s in o ne s id e proposed traffic fixed-time traffic fig. 11. the number of vehicles passed in one side compared to the available vehicles in other sides. 4. conclusions the traditional traffic light system wasted a lot of time because it has a fixed interval time, and does not depend on the number of vehicles in the sides of intersection. to reduce the wasted time another approach must be used. the best approach and best solution to minimize the lost time is the intelligent traffic light system. in this paper, the fpga model of a proposed design intelligent traffic light system with saving power has been presented. the intelligent traffic light system is illuminating traffic lights according to the presence or absence of vehicles on the sides of the intersection. this system is disposal any lost time through the transition from one traffic light state to another when the state is not useful and useless time. so the waiting time of red light will reduce. furthermore, the system will turn off all traffic lights when it senses the absence of vehicles at all sides of intersection to save the power. results showed that the proposed system is able to pass three times the number of vehicles of fixed-time system in a one side when the other sides are empty. 5. references [1] h. n. abdullah, i. a. hashim, and b. h. abd " design and implementation of an intelligent traffic light system," engineering and technology journal, vol.28, no.15, pp. 50795087, 2010. [2] b. h. abd, "modeling and simulation of intelligent traffic light," the engineering conference in control, computer, and mechatronics. university of technology, 2011. [3] k. l. shunmuganathan, v. vasudevan and p. yogesh, , "intelligent communicating agent and their performance for multi-agent based traffic controllera new approach for roads using jade", international journal of soft computing vol. 2, no. 1, pp. 17-20, 2007. [4] k. k. tan, m. khalid, and r. yusof, december, "intelligent traffic lights control by fuzzy logic". malaysian journal of computer science, vol. 9 no. 2, pp. 29-35, 1996. [5] s. y. aye, "design and construction of lan based car traffic control system", proceedings of world academy of science, engineering and technology, vol. (36), issn 2070-3740, december 2008. [6] wu h. m. changyun, "design of intelligent traffic light control system based on traffic flow," computer and communication technologies in agriculture engineering (cctae), international conference, vol. 3, pp. 368 – 371, chengdu, 12-13 june 2010. [7] a. albagul, m. hrairi, wahyudi and m.f. hidayathullah, "design and development of sensor based traffic light system", ali hashim jryian al-khwarizmi engineering journal, vol. 8, no.4, pp 96 -105(2012) 104 american journal of applied sciences, vol. (3), no. (3), pp. (1745-1749), 2006. [8] f. khan, l. yuan, c.-n. chuah, and s. ghiasi, “a programmable architecture for scalable and real-time network traffic measurements,” in ancs ’08: proceedings of the 4th acm/ieee symposium on architectures for networking and communications systems, 2008, pp. 109– 118. [9] j. l. jerez, g. a. constantinides, e. c. kerrigan and k. v. ling, “parallel mpc for real-time fpga-based implementation,” preprints of the 18th ifac world congress milano (italy), pp. 1338-1343, august 28 september 2, 2011. )2012( 96105 ، صفحة4، العدد8مجلة الخوارزمي الھندسیة المجلد علي ھاشم جریان 105 لنظام االشارات المروریة الذكي الحافظ للطاقة الكھربائیة) fpgo(نموذج علي ھاشم جریان بغداد -معھد التكنولوجیا/ قسم المیكانیك aadd_ssd@yahoo.com : البرید االلكتروني الخالصة یتك ون نظ ام اإلش ارات المروری ة ال ذكي م ن متحسس ات توض ع عل ى . لنظام اإلشارات المرویة الذكي الحافظ للطاقة الكھربائیة fpgaتم بناء نموذج وذلك من ،قوم ھذا النظام على تقلیل وقت االنتظار عندما یكون ضوء اإلشارة المروریة حمراءی. أطراف جوانب التقاطع لتحسس وجود أو غیاب المركبات تم بناء ھذا النظام باستخدام . وذلك لعدم وجود المركبات فیھا ،خالل االنتقال من حالة ضوئیة مروریة إلى حالة أخرى عندما تكون الحالة األولى تھدر الوقت لق د أظھ رت . spartan-3a xc3s700a fpga kitوت م تنفی ذه باس تخدام ، xilinx ise 9.2i packageس تخدام وت م محاكات ھ با vhdlلغة الـ .نتائج محاكاة ھذا النموذج بان نظام اإلشارات المرویة الذكي المقترح قد حقق المتطلبات التشغیلیة المحددة mailto:aadd_ssd@yahoo.com final tarik zeyad /al-khwarizmi engineering journal ,vol.1, no. 1,pp 52-60 (2005) 52 al-khwarizmi engineering journal al-khwarizmi engineering journal, vol.1, no.1,pp 52-60, (2005) speech signal compression using wavelet and linear predictive coding dr. tarik zeyad ahlam hanoon electrical engineering dept. / college of engineering / university of baghdad abstract a new algorithm is proposed to compress speech signals using wavelet transform and linear predictive coding. signal compression based on the concept of selecting a small number of approximation coefficients after they are compressed by the wavelet decomposition (haar and db4) at a suitable chosen level and ignored details coefficients, and then approximation coefficients are windowed by a rectangular window and fed to the linear predictor. levinson durbin algorithm is used to compute lp coefficients, reflection coefficients and predictor error. the compress files contain lp coefficients and previous sample. these files are very small in size compared to the size of the original signals. compression ratio is calculated from the size of the compressed signal relative to the size of the uncompressed signal. the proposed algorithms where fulfilled with the use of matlab package. keyword: wavelet, speech coding, linear predictive coding, levinson durbin. 1. introduction compression can be achieved by reducing redundancy. it is the process of reduction in the amount of signal space that must be allocated to a given message set or data sample set. this signal space may be in a physical volume, such as data storage medium: an interval of time, such as the time required to transmit a given message set [1][2]. bit rate reduction or data reduction are all terms which mean basically the same thing it means that the same information is carried using smaller quantity or rate of data.[3][4] compression is the process of converting an input data stream [the source stream or the original raw data] into another data stream [the output or the compressed data] that has a smaller size. 2. the proposed speech signal compression algorithm the proposed compression system divided into four headlines: 2.1 preprocessing part: • acquisition of the received signal in an if mode, in our work the signals are recorded using microphone in different places and conditions, so a number of signals are recorded. • using haar and db4 wavelet decomposition algorithm to decompose the received speech signal. • after that the decomposed frames are segmented into 256 samples per segment. accordingly the time or frequency variations are viewed in small intervals. by this way the processing will be more accurate. • now each frame is multiplied by finite – duration window. this process is called windowing. rectangular window having duration of one-pitch periods. this produces output spectrum very close to that of the vocal tract impulse response. the equation of a rectangular window is:       −<< = otherwise nn nr 0 101 )(ω (1) where ωr(n) is the signal samples inside the window. now the data is ready to an efficient feature extraction part. tarik zeyad /al-khwarizmi engineering journal ,vol.1, no. 1,pp 52-60 (2005) 53 2.2 the feature extraction part: the feature extracting helps to reduce noise as well as the signal component redundant to the process of compression. discrete wavelet transform is more popular in the field of digital signal processing. to parameterize the speech signal it is first decomposed in a dyadic form. the decomposition processed only on the low frequency branches, which is the approximation coefficients since it is more intelligible part as well as most of the information in this part, while the details coefficients are ignored since they contain noise. all data operations can be performed using just the corresponding wavelet coefficients and hence approximation coefficients fed to the next stage (linear predictor stage). 2.3 linear prediction based coefficients calculation: the linear prediction (lp) provides parametric modeling techniques, which is used to model the spectrum as an autogressive process. these parametric models are basically used in compression system. the ability of linear prediction as applied to speech, however, lies not only in its predictive function but also in the fact that it gives a very good model of the vocal tract, which is useful for both practical and theoretical purposes for representing speech for low bit transmission or storage. 2.3.1 autocorrelation method for calculating the lpc autocorrelation method was used for many reasons: 1) it requires less amount of storage. 2) the number of multiplication needed for computation is small. 3) the number of sample will be as large as several pitch periods to ensure reliable results. 4) the number of poles will depend on the sampling rate, it is known that for every 1khz sampling rate two poles (one conjugate pole) will be needed. the prediction error is represented by: ∑ = −−= p i i )in(sa)n(s)n(e 1 (2) where s(n) is the value of sample n and ∑ = − p i i )in(sa 1 is the predicted value of sample (n). the prediction parameter (ai) is known and determined by minimizing the mean square error (mse) e[e2(n)]. these coefficients are determined by solving (p) (order of lp) with (p) unknowns that obtained by minimizing mse           =                     −− − − )p(r)(r....)p(r)p(r .... )p(r....)(r)(r )p(r....)(r)(r mmmmm r(2) r(1) a(p) a(2) a(1) 021 201 110 ………. (3) where r(n) is the correlation of the window with it self with shift equals to n (r(0) is the autocorrelation). this type of matrix is called toeplitz matrix where all elements along a given diagonal are equal and it is very easy to invert it. 2.3.2 levinson-durbin procedure the l-d algorithm is a recursive algorithm that solves the (a=r-1r). it is very computationally efficient. during this algorithm a number of coefficients are generated which are {ai} a set of coefficients and {ki}, which is called reflection coefficients. these coefficients can be used to rebuild the set of filter coefficients {ai} and can guarantee a stable if their magnitudes are strictly less than one. n 50 100 150 200 250 256 1 fig. (1) rectangular window of 256-sample length. tarik zeyad /al-khwarizmi engineering journal ,vol.1, no. 1,pp 52-60 (2005) 54 the levinson durbin algorithm is summarized by [1]: (4) (5) (6) (7) (8) (9) fig. (2) shows the flow chart of the compression of speech signal while fig. (4), illustrates the flow chart of the decompression of speech signal. p j a a p i e j i r a i r ki r e p j j i i j i j ≤ ≤ = ≤ ≤     − − = = − − = − ∑ 1 1 / ) ( ) ( ) 0 ( ) ( e k e i i i − = − ) 1 ( ) 1 ( 2 ) ( i j a k a a i j i i i j i j − ≤ ≤ + = − − − 1 1 ) 1 ( ) 1 ( ) ( ki a i i = ) ( ) 1 ( 1 1 ) 1 ( ) 0 ( tarik zeyad /al-khwarizmi engineering journal ,vol.1, no. 1,pp 52-60 (2005) 55 start sampled at frequency (8,22)khz , aid s(n) with 8bit&16bit accuracy segmentaion 256 sample per segment and framing no overlap sample feature extraction (dwt) to 3 level [(c(i,:),l(i,:)]=wavedec(seg(i,:),n,w) wavelet coefficients: [d3(i,:), d2(i,:),d1(i,:)]=ignore [a3(i,:)]=appcoff(c(i,:),l(i,:),w) windowing (rectangular window) with no overlap samples lpc-analysis via l-d method lp coefficients ai = . . . . .. . .. a(p+1) for each frame final prediction error is e<3*10-5? yes no fig.(2) flow chart of compression speech signal. storage device lp coefficients for each frame first samples from each frame from approximation coefficient,w,n input speech signal x(t) save predictor error stop is that last frame yes no 1st samples from each frame tarik zeyad /al-khwarizmi engineering journal ,vol.1, no. 1,pp 52-60 (2005) 56 fig.(3) flow chart of decompression speech signal. approximation coefficient = prediction signal ( from storage coefficients) + prediction error :)],(+:),(ˆ[=:)],(3[ ieisia n storage device lp coefficients and previous sample from each frame and prediction error reconstruct the signal level from coefficient stop output speech signal is that last frame? yes no start tarik zeyad /al-khwarizmi engineering journal ,vol.1, no. 1,pp 52-60 (2005) 57 3. evaluation tests of the algorithm 3.1 tested speech samples: the test material will contain five speech samples stored in five files, the format of these files are wave format, each file has a different size with respect to the other files of normal arabic sentences altered by different speakers. the type of the digital speech is pulse code modulation (pcm) and the tested speech samples have 8-bit/samples or 16bit/samples. the properties of tested wave data are presented in table (1). table (1) : properties of tested wave data signal s1 s2 s3 s4 s5 file name allah aa1 aa2 daleel prog file type wave file wave file wave file wave file wave file file size byte 190640 123392 160000 260664 296192 media length (s) 23 15 20 14 13 file format pcm pcm pcm pcm pcm 8 khz 8 khz 8 khz 22 khz 22 khz 8-bit mono 8-bit mono 8-bit mono 16-bit mono 16-bit mono 4.2 performance measure the compression algorithm used in this project has been tested on a number of sounds (about 5-files). table (2) shows performance measures of speech signals. to evaluate the performance of a compression technique the criteria of measuring distortion in reconstructed sound files are defined. these criteria are necessarily applied. these include signal to noise ratio, peak signal to noise and normalized root mean square error. the above quantities are calculated using the following formats [1]: 1-signal to noise ratio       σ σ = 2 2 e x 10log 10snr (10) xσ is the mean square of the speech signal and eσ is the mean square difference between the original signal and reconstructed signal. 2-peak signal to noise ratio ( ) 2r-x nxlog 10 psnr 2 10= (11) n is the length of reconstructed signal, x is the maximum absolute square value of the signal x and 2r-x is the energy of the difference between the original and reconstructed signals. 3-normalized root mean square error ( ) ( )2 2 (n)(n) (n)(n) x rx nrmse µ− − = (12) x(n) is the speech signal, r(n) is the reconstructed signal and μx(n) is the mean of speech signal . tarik zeyad /al-khwarizmi engineering journal ,vol.1, no. 1,pp 52-60 (2005) 58 table (2) performance measures of speech signals. signal wavelet snr psnr nrmse s1 haar db4 5.4328 6.8434 5.9214 5.6851 1.2902 1.3258 s2 haar db4 4.2883 4.7211 13.2997 13.1877 1.2686 1.2844 s3 haar db4 3.0827 3.3462 10.5618 10.4571 1.1904 1.2048 s4 haar db4 7.2869 11.7732 15.0258 14.7718 1.3448 1.3841 s5 haar db4 8.2198 12.9519 16.6317 16.3998 1.3580 1.3948 5. compression performance this section gives the computation of the compression performance of the proposed method in tables (3) and (4) [2]. this table is computed according to the following equations: the first column in this table is the name of the file. the second column is the size of the file before compression and the size of the output file (that represents lpc coefficient and previous samples of each speech signal). the compression ratio is the third column computed by using equation number (13). the fourth column is the compression factor computed by applying equation number (14). the 5th column is the expression computed using equation number (15). finally the expression gain is computed using equation number (16). the results of compression performance are shown in table (3) by using haar wavelet transform and in table (4) by using db4 wavelet transform. table (3) compression performance results when using haar wavelet transform. file name input file size output file size cr % cf ex compression gain s1 190640 15624 8.19 12.20 91.81 108.6 s2 123392 10080 8.16 12.24 91.83 108.7 s3 160000 13104 8.19 12.21 91.81 108.6 s4 260664 61936 23.76 4.208 76.24 62.413 s5 296192 56448 19.05 5.247 80.94 71.99 average 13.47 9.223 86.522 92.04 compression ratio = the size of output/the size of input <1 ……..(13) compression factor = the size of input/the size of output >1 …… (14) the expression =100*(1-compression ratio) …..(15) compression gain = 100 log(reference size/compressed size) ……(16) tarik zeyad /al-khwarizmi engineering journal ,vol.1, no. 1,pp 52-60 (2005) 59 table (4) compression performance results when using db4 wavelet transform. file name input file size output file size cr% cf ex compression gain s1 190640 18480 9.69 10.316 90.306 101.35 s2 123392 11928 9.66 10.344 90.33 101.47 s3 160000 15456 9.66 10.350 90.34 101.5 s4 260664 73696 28.27 3.537 71.72 54.86 s5 296192 67032 22.36 4.418 77.36 64.529 average 15.982 7.793 84.086 84.74 6.conclusions: a significant advantage of using wavelets for speech coding is that the compression ratio can be varied. this work shows that wavelet decomposition in conjunction with other techniques such as lpc is promising compression techniques which make use of the elegant theory of wavelets. several conclusions can be drawn: 1the two proposed techniques work better with clean source materials; noisy sound waveforms produce poor results and need additional processing techniques. 2choosing the right decomposition level in the dwt is important for many reasons, for processing speech signals no advantage is gained beyond level 3 usually processing at lower scale leads to a better compression ratio. 3linear predictive technique causes time delay and some loss of quality. but they are negligible in terms of cost when compared with the advantages of storage space saving, smaller b.w requirement, lower power consumption and small product size. 4this proposed method could be classified in the field of symmetrical compression. this case occurs when the compression and decompression use basically the same algorithm but work in opposite directions. wt and lpc are used together to get more compression ratio, and depending on these ratios the algorithm gives promising results, although each of them can be used individually to compress speech signals but by using wt technique alone the compression ratio can be varied by changing the level of decomposition while the compression ratio is constant when lpc is used. keyword: wavelet, speech coding, linear predictive coding, levin son durbin 7. references [1] rabiner l.r, and schafer r.w., (1990), “digital processing of speech signals” , prentice hall. [2] jabber m., (1999), “ speech compression and recognition using wavelet transform”, an m.sc. thesis, university of baghdad, college of engineering, electrical engineering department. [3] markel j.d. and gray a.h., (1976), “linear prediction of speech coding”, springer verlag, new york. [4] koul m., (1975), “ linear prediction tutorial”, proceeding of ieee , vol.63, no.4, pp.461-580, april. [5] belloch g.e., (2001), “introduction to data compression”, cavnege mellon university, web site, october. tarik zeyad /al-khwarizmi engineering journal ,vol.1, no. 1,pp 52-60 (2005) 60 ضغط الملفات الصوتية باستعمال تحويل المويجة والتشفير ذو األستنتاجات الخطية اد احالم حنونطارق زي.د جامعة بغداد/ كلية الهندسة /قسم الهندسة الكهربائية :الخالصة تم في هذا البحث استخدام التحويل نوع التحويل المويجة واستخدام المرشح ذو معامالت االستنتاج الخطية لغرض db4و haarنوع المسمى تحويل المويجة لتحويتخدام التم أس. ضغط حجم الملفات التي تحتوي على تسجيالت صوتية لغرض تنفيذ عملية الضغط األولى واحتساب نسبة ضغط الملفات بأستخدام كافة الطرق أما بصورة مفردة أو بصوزة وكانت نسبة ضغط الملفات تعتمد على levinson durbinتم احتساب معامالت المرشح باستخدام خوارزمية . مجتمعة خطأ المرشحات تم مقارنة حجم الملفات المضغوطة مع الملفات األصلية وكذلك أحتساب نسبة الخطأ التي تنتج من نسبة .عملية الضغط وكانت جميع الملفات التي تم ضغطها هي ملفات قيم final isam m. ali./ al-khwarizmi engineering journal, vol. 1, no. 1, pp 73-82 (2005) ٧٣ al-khwarizmi engineering journal al-khwarizmi engineering journal, vol.1, no.1,pp 73-82, (2005) introduction: a capillary tube is the heart of a small vapor compression refrigeration equipment such as room air conditioners, household refrigerators and freezers. it is simple, reliable and inexpensive. capillary tubes commonly used as the expansion and refrigerant controlling device.however with the environmentalists creating a hue and cry over the use of existing cfc and hcfc refrigerants in refrigeration industry, it is now becoming more important to switch over to refrigerants which are more environmental friendly. thus, a need was felt that if database could be created for more commonly used refrigerants with capillary tubes as expansion devices for smaller refrigeration systems, it shall extremely useful for retrofitting the systems with new or alternative refrigerants. especially in the past 15 years or so, the flow characteristics of refrigerant passing through capillary tubes have been widely studied experimentally or analytically with alternative and common traditional refrigerants. hartnett and minkowcz [1] present theoretical comparison of the flow characteristics of many pairs of refrigerants flowing through adiabatic capillary tubes. the two phase flow model developed was based on homogeneous flow assumption. numerical results showed that the traditional refrigerants consistently gave lower pressure drops than the environmentally acceptable alternative refrigerants, which resulted in longer tube lengths. somchai [2] developed a model to study the flow characteristics in adiabatic capillary tubes of various refrigerants. in addition, an example of capillary tube selection chart developed from the pressure numerical simulation was shown. the chart can be practically used to select the capillary tube size from the flow rate and flow condition or to determine mass flow rate directly from a given capillary tube size and flow condition. abstract: experimental work has been performed on three capillary tubes of different lengths and diameters using r-12 and r-134a. the test also studies the effect of discharge and speed of evaporator fan. the results clearly showed that refrigerant type and discharge significantly influence the temperature drop across the capillary tube. while the speed of evaporator fan has small effect. experimental results showed that the temperature gradient for the two refrigerants are the same, but after approximatly one meter the temperature gradient of r-134a is steeper than r-12. keyword: refrigeration, capillary tube, r-12, r134a. an experimental study of capillary tubes behavior with r-12 and r-134a issam m.ali hani a.jasim mechanical engineering dept/ college of engineering/university of baghdad isam m. ali./ al-khwarizmi engineering journal, vol. 1, no. 1, pp 73-82 (2005) ٧٤ visinee and somchai [3] present new correlation for the practical sizing of adiabatic capillary tubes. the developed model is used as an effective tool for studying the effects of relevant parameters on capillary tube length. the correlation can be used to integrate with system models working with alternative refrigerants for practical design and optimization. pakawat [4] et al developed a numerical study on the local pressure distribution of some common traditional and alternative refrigerants flowing in adiabatic capillary tubes. numerical results show that the alternative refrigerants consistently give higher pressure gradients than the traditional refrigerants. this model is an important tool for selecting the length of the capillary tube. sami et al [5] present experimental data on capillary tube using various new alternatives under different geometrical parameters (length, diameter, as well as entrance conditions). the results clearly showed that the pressure drop across the capillary tube is significantly influenced by the diameter of the capillary tube, inlet conditions to the capillary and refrigerant type. therefore, to be a guide line in the future for selecting the appropriate refrigerants, in the present study, the main concern is to study on the temperature distribution of two refrigerants (r-12 and r134a) along the capillary tubes, of different lengths and diameters, and to compare the flow characteristics between them. experimental apparatus and measurements: an experimental set up has been fully instrumented with pressure, temperature, electrical sensors as well as refrigerant flow metering device. fig.1 show a schematic diagram of experimental set up. the vapor compression system was composed mainly of: • 1/5 hp hermetic compressor. • variable flow forced air system with condenser and evaporator, which includes a series of 8-glass tube for visualizing, set by step, the collection and evaporation of liquid. • 10 valves for interception. • 3 capillary tubes of various lengths and diameters made from copper. table (1) presents the capillary tube geometry. the two pressures were mesured using calibrated gauge presures. digital thermometer was used to measure the surface temperature along the capillary tubes. table (1) shows the positions of measurement along the three capillary tubes. calibrated flow meter was installed in the liquid line to measure the mass flow rate to the capillary tube test section. first, all tests carried out using r-134a with polyol-esters oil. following each, the system was drained , evacuated and charge with refrigerant r-12 with appropriate oil. to get required charge , during charging ,disappear of bubbles in flow meter give a signal of suitable charge. the parameters observed during the course of this study were temperature profile along the capillary tubes, discharge and power consumpsion. usually ,20 to 45 minutes were needed for the system to reach steady state operation at a desired compressor discharge pressure. the three capillary tubes in test had different coiling. our test neglected the effects of coiling because it is very small. s.j. kuehl and v.w isam m. ali./ al-khwarizmi engineering journal, vol. 1, no. 1, pp 73-82 (2005) ٧٥ goldschmidt[6] noted that coiling increases the pressure drops by 5% only. results and discussion: when capillary diameter increases, temperature gradient becomes more extremly for the two refrigerants (r12,r134a) as shown in figs 2,3,and 4. this phenomena is evident because the heat transfer between the air and refrigerant is higher . the same figures explain that temperature gradiant for r12 is faster. temperature difference (∆t) in the case of refrigerant r12 is greater than refrigerant r134a. that means more heat transfer. capillary tube (1) capillary tube (2) capillary tube (3) capillary diam. 0.81 mm 1.4 mm 1.5 mm capillary length 120 cm 135 cm 160 cm temp. port # 1 0 cm 0 cm 0 cm temp. port # 2 30 cm 30 cm 30 cm temp. port # 3 60 cm 60 cm 60 cm temp. port # 4 90 cm 90 cm 90 cm temp. port # 5 105 cm 120 cm 120 cm temp. port # 6 120 cm 135 cm 150 cm 160 cm figure (1) schematic diagram of experimental set up pressure gauges compress or condensor evaporat or capillary tubes table 1 capillary tube geometry isam m. ali./ al-khwarizmi engineering journal, vol. 1, no. 1, pp 73-82 (2005) ٧٦ also increasing the diameter of capillary tubes leads to coincident of the curves of both refrigerants and it seems clearly at starting point. decreasing the discharge causes faster temperature gradient as shown in figs.5, 6,7,8,9, and 10 for both r12, r134a because of high amounts of heat transfer. as the diameter decreases, the curves become more smoothly and the effect of discharge becomes small. for the first capillary tube minimum discharge leads to high ∆t) i.e more heat transfer). notice that the gap between curves resulting from decreasing the discharge at starting point increases as the diameter of capillary tube increase. as a comparison between r12, r134a the approch of curves approximates with decreasing the diameter. this is evident between fig.5 and fig.6. 0 25 50 75 100 125 capillary tube length(mm) fig.(1) 0 5 10 15 20 25 30 35 40 45 50 t em pe ra tu re ( c ) capillary no.1 l=120 mm, d= 0.81 mm tamb=35 c q=0.25 l/min vevap=0 rev/min r-134a r-12 0 25 50 75 100 125 150 capillary tube length (mm) fig(2) 0 5 10 15 20 25 30 35 40 45 50 t em pe ra tu re ( c ) capillary no.2 l=135 mm, d= 1.24 mm tamb=35 c q=0.25 l/min vevap=0 rev/min r-134a r-12 0 25 50 75 100 125 150 175 capillary tube length (mm) fig.(3) 0 5 10 15 20 25 30 35 40 45 50 te m pe ra tu re ( c ) capillary no.3 l=160 mm, d= 1.5 mm tamb=35 c q=0.25 l/min vevap=0 rev/min r-134a r-12 fig.2 temperature gradient along capillary tube no.1 of two refrigerants fig.3 temperature gradient along capillary tube no.2 of two refrigerants fig.4 temperature gradient along capillary tube no.3 of two refrigerants isam m. ali./ al-khwarizmi engineering journal, vol. 1, no. 1, pp 73-82 (2005) ٧٧ 0 25 50 75 100 125 capillary tube length(mm) fig.(4) 0 10 20 30 40 50 t em pe ra tu re ( c ) capillary no.1,r-12 l=120 mm, d= 0.81 mm tamb=35 c vevap=0 rev/min q= 0.16 l/min q= 0.23 l/ min q= 0.06 l/min 0 25 50 75 100 125 capillary tube length(mm) fig.(5) 0 10 20 30 40 50 t em pe ra tu re ( c ) capillary no.1,r-134a l=120 mm, d=0.81 mm tamb=35 c vevap=0 rev/min q= 0.16 l/min q= 0.26 l/ min q= 0.06 l/min 0 25 50 75 100 125 150 capillary tube length(mm) fig.(7) 0 10 20 30 40 50 t em pe ra tu re ( c ) capillary no.2,r-134a l=135 mm, d= 1.24 mm tamb=35 c vevap=0 rev/min q= 0.29 l/ min q= 0.22 l/min q= 0.005 l/min 0 25 50 75 100 125 150 175 capillary tube length(mm) fig.(8) 0 10 20 30 40 50 t em pe ra tu re ( c ) capillary no.3,r-12 l=160 mm, d= 1.5 mm tamb=35 c vevap=0 rev/min q= 0.16 l/min q= 0.23 l/ min 0 25 50 75 100 125 150 capillary tube length(mm) fig.(6) 0 10 20 30 40 50 t em pe ra tu re ( c ) capillary no.2,r-12 l=135 mm, d= 1.24 mm tamb=35 c vevap=0 rev/min q= 0.16 l/min q= 0.23 l/ min q= 0.06 l/min 0 25 50 75 100 125 150 175 capillary tube length(mm) fig.(9) 0 10 20 30 40 50 t em pe ra tu re ( c ) capillary no.3,r-134a l=160 mm, d= 1.5 mm tamb=35 c vevap=0 rev/min q= 0.3 l/ min q= 0.24 l/min fig.5 temperature gradient along capillary tube no.1 under different discharges using r-12 fig.6 temperature gradient along capillary tube no.1 under different discharges using r-134a fig.9 temperature gradient along capillary tube no.3 ,under different discharges using refrigerant r-12 fig.7 temperature gradient along capillary tube no.2 under different discharges using refrigerant r-12 fig.10 temperature gradient along capillary tube no.3 under different discharges using refrigerant r-134a fig.8 temperature gradient along capillary tube no.2 under different discharges using refrigerant r-134a isam m. ali./ al-khwarizmi engineering journal, vol. 1, no. 1, pp 73-82 (2005) ٧٨ the effect of speed of evaporator fan is more evident in the first capillary tube compare with the two others.( i.e decreasing diameter of capillary tube causes increasing the effect of (v) ). see figs.11, 12,13,14,15 and 16. for the first capillary tube increasing speed of evaporator leads to faster temperature gradient. while increasing of speed have small effect on the second and third capillary tubes. ∆t for refrigerant (r134a) is greater than that of refrigerant (r12) at small and middle speed of evaporator. in general ∆t increases with the diameter for the two refrigerants at all speeds. temperature along the tube was measured with surface thermocouples. the flash point at which vaporization starts is accompanied by a sudden drop in temperature. the tube wall temperature drops accordingly as the vaporizing starts. fig.2 shows that vaporization starts at a distance after (50 cm) for both r12 and r134a because of a sudden drop in temperature. for the third capillary tube (vaporization is starting early (i.e increasing the diameter causes faster vaporization). see figs.3and 4. decreasing the discharge leads to faster vaporization. it seems clearly in figs.5, 6,7,8,9 and 10. while decreasing the speed has no effect upon refrigerant vaporization. see figs. 11,12,14,15 and 16.table (2) explain that the discharge pressure (ph) of refrigerant r12 is higher than r134a.while the suction pressure (pl) approximately constant. so pressure drop (∆p) of refrigerant r12 is higher than r134a.decreasing the discharge leads to higher (∆p). while the effect of evaporator fan is negligible. second and third capillary tubes have similar approach except that the suction pressure is not constant see tables (3, 4). 0 25 50 75 100 125 capillary tube length(mm) fig.(10) 0 5 10 15 20 25 30 35 40 45 50 t em pe ra tu re ( c ) capillary no.1,r-12 l=120 mm, d= 0.81 mm tamb=35 c q= 0.3 l/min vevap.=0 rev/min vevap.= rev/min vevap.= rev/min fig.11 temperature gradient along capillary tube no.1under different air velocities using refrigerant r-12 0 25 50 75 100 125 capillary tube length(mm) fig.(10) 0 5 10 15 20 25 30 35 40 45 50 t em pe ra tu re ( c ) capillary no.1,r-12 l=120 mm, d= 0.81 mm tamb=35 c q= 0.3 l/min vevap.=0 rev/min vevap.= rev/min vevap.= rev/min fig.12 temperature gradient along capillary tube no.1 under different air velocities using refrigerant r-134a 0 25 50 75 100 125 150 capillary tube length(mm) fig.(11) 0 10 20 30 40 50 t em pe ra tu re ( c ) capillary no.2,r-12 l=135 mm, d= 1.24 mm tamb=35 c vevap.=0 rev/min vevap.= rev/min vevap.= rev/min fig.13 temperature gradient along capillary tube no.2 under different air velocities using refrigerant r-12 isam m. ali./ al-khwarizmi engineering journal, vol. 1, no. 1, pp 73-82 (2005) ٧٩ 0 25 50 75 100 125 150 capillary tube length(mm) fig.(12) 0 10 20 30 40 50 t em pe ra tu re ( c ) capillary no.2,r-134a l=135 mm, d= 1.24 mm tamb=35 c vevap.=0 rev/min vevap.= rev/min vevap.= rev/min fig.14 temperature gradient along capillary tube no.2 under different air velocities using refrigerant r-134a 0 25 50 75 100 125 150 175 capillary tube length(mm) fig.(13) 0 10 20 30 40 50 t em pe ra tu re ( c ) capillary no.3,r-12 l=160 mm, d= 1.5 mm tamb=35 c q= 0.3 l/min vevap.=0 rev/min vevap.= rev/min vevap.= rev/min fig.15 temperature gradient along capillary tube no.3 under different air velocities using refrigerant r-12 0 25 50 75 100 125 150 175 capillary tube length(mm) fig.(14) 0 10 20 30 40 50 t em pe ra tu re ( c ) capillary no.3,r-12 l=160 mm, d= 1.5 mm tamb=35 c q=0.3 l/min vevap.=0 rev/min vevap.= rev/min vevap.= rev/min fig.16 temperature gradient along capillary tube no.3 under different air velocities using refrigerant r-134a table 2.data of 1st capillary tube refrigerant discharge l/min vevap m/s ph bar pl bar ∆p bar power kw r12 0.25 0 10.5 1.4 9.1 0.3 r134a 0.25 0 10.2 1.4 8.8 0.32 r12 0.16 0 10.5 1 9.5 0.28 r134a 0.16 0 10 0.8 9.2 0.28 r12 0.3 60 11.5 1.8 9.7 0.36 r134a 0.3 60 11 1.8 9.2 0.34 r12 0.3 120 11.5 1.9 9.6 0.38 r134a 0.3 120 11 1.8 9.2 0.36 isam m. ali./ al-khwarizmi engineering journal, vol. 1, no. 1, pp 73-82 (2005) ٨٠ refrigerant discharge l/min vevap m/s ph bar pl bar ∆p bar power kw r12 0.25 0 10 1.4 8.6 0.32 r134a 0.25 0 10 1.7 8.3 0.32 r12 0.005 0 9.2 0.3 8.9 0.23 r134a 0.005 0 8.8 0.2 8.6 0.22 r12 0.3 60 11 1.8 9.2 0.35 r134a 0.3 60 11 2.3 8.7 0.37 r12 0.3 120 11.3 2.2 9.1 0.4 r134a 0.3 120 11 2.3 8.7 0.4 refrigerant discharge l/min vevap m/s ph bar pl bar ∆p bar power kw r12 0.3 0 10 1.8 8.2 0.34 r134a 0.3 0 9.5 1.8 7.7 0.32 r12 0.24 0 9 0.6 8.4 0.26 r134a 0.24 0 8.5 0.5 8 0.22 r12 0.3 60 10 2.1 7.9 0.36 r134a 0.3 60 10 2.2 7.8 0.36 r12 0.3 120 10.5 2.4 8.1 0.4 r134a 0.3 120 10.2 2.5 7.7 0.4 table 3. data of 2nd capillary tube table 4. data of 3rd capillary tube isam m. ali./ al-khwarizmi engineering journal, vol. 1, no. 1, pp 73-82 (2005) ٨١ in general power consumption for refrigerant r12 is higher for the three capillary tubes. conclusion: experimental data showed that the temperature gradient for the two refrigerants are the same, but after approximately one meter the temperature gradient of r-134a is faster than r-12.that means more heat transfer .decreasing the discharge causes faster temperature gradient leads to faster vaporization. the effect of changing the discharge becomes unsensible for small diameters. changing speed of evaporator fan is evident in the first capillary tube, while at large diameters the effect is negligible .heat transfer for r134a is greater than r-12 at small and middle speed of evaporator .discharge pressure of r12 is higher than r134a while suction pressure approximately constant. that means pressure drop of r-12 is higher. power consumption for r-12 is higher for three capillary tubes. references: 1. j.p hartnett and w.j. minkowycz " a comparison of the flow characteristics of refrigerants flowing through adiabatic capillary tubes" heat mass transfer,vol. 27, no.5,pp 611-621,2000. 2. somchi wongwises, worachet pirompach" flow characteristics of pure refrigerants and refrigerant mixtures in adiabatic capillary tubes". applied thermal engineering 21(2001) 845-861. 3. visinee trisaksri and somchai wongwises"correlations for sizing adiabatic capillary tubes" international journal of energy research 2003:27:11451164(doi:10.1002/er.937). 4. pakawat et al "pressure distribution of refrigerant flow in an adiabatic capillary tube" science asia 28 (2002):71-76. nomenclature: d: inside diameter of capillary tube(mm). l: length of capillary tube (cm) ph: discharge pressure (bar). pl: suction pressure (bar). q: refrigerant discharge (l/min). tamb: ambient temperature (oc). v: speed of air delivered by evaporator fan (m/s). ∆p: difference between discharge and suction pressure (bar). ∆t: difference between maximum and minimum temperature along capillary tube (oc). isam m. ali./ al-khwarizmi engineering journal, vol. 1, no. 1, pp 73-82 (2005) ٨٢ دراسة مختبرية لمنظومة تبريد تحتوي ثالثة أنابيب شعريةباستخدام نوعين (r12-r134a) من موانع التثليج عصام محمد علي هاني عارف جاسم جامعة بغداد/كلية الهندسة/قسم الهندسة الميكانيكية :الخالصة األقطار واألطوال في منظومة تثليج باستخدام موائع التثلـيج اختبار عملي تم اجراءه على ثالثة أنابيب شعرية مختلفة r-12 ,r-134a .النتائج بينت بوضـوح .االختبار هو دراسة تأثير تغير معدل التدفق و سرعة مروحة المبخر على المنظومة سرعة مروحة المبخر لهـا بينما . أن نوع المائع المستخدم ومعدل التدفق يؤثران على تغير درجات الحرارة على طول األنبوب االختبار العملي بين كذلك تغير درجات الحرارة على طول األنابيب الشعرية متشابهة بالنسبة للمائعين ولكن بعد متر . تأثير قليل . r12أسرع من r134aواحد من طول األنبوب الشعري فأن التغير لمائع al-khwarizmi engineering!!! journal al-khwarizmi engineering journal, vol. 7, no. 2, pp 47 54 (2011) nahrain mobile learning system (nmls) mahmood sami abd al-kareem * mumtaz al-mukhtar ** * department of computer and continuous education/ presidency of al-nahrain university/ university of al-nahrain email: mahmood_sime@yahoo.com !** department of international network/ information engineering college/ university of al-nahrain email: mumtaz_almukhtar@yahoo.com (received 17 january 2011; accepted 31 may 2011) abstract the work in this paper involves the planning, design and implementation of a mobile learning system called nahrain mobile learning system (nmls). this system provides complete teaching resources, which can be accessed by the students, instructors and administrators through the mobile phones. it presents a viable alternative to electronic learning. it focuses on the mobility and flexibility of the learning practice, and emphasizes the interaction between the learner and learning content. system users are categorized into three categories: administrators, instructors and students. different learning activities can be carried out throughout the system, offering necessary communication tools to allow the users to communicate with each other through forums, sms and e-mails. nmls platform is based on 3g mobile phone technology and adopted wap as a solution for the system platform. the nmls framework is based on three layers, which are presentation layer, business logic layer and data layer. keywords: nahrain mobile learning system; short message service; wireless application protocols; multimedia messaging service; mobile learning; personal digital assistant; wireless fidelity; general packet radio service; extensible hypertext markup language; java database connectivity. 1. introduction the rapid development of wireless infrastructure and the advent of mobile devices in everyday life of people push the research to combine those two domains, which results in the emerging of mobile learning [1]. mobile technologies potentially promote, facilitate, and enhance student collaboration and interaction. processes that serve as a means for accessing, discovering, discussing, and sharing environmental concerns via multimedia messaging service (mms), short message service (sms), electronic mail (e-mail), wireless application protocols (wap), or chatting. students can converse with each other, question each other, and share opinions about environmental concerns. collaboration could also occur outside the classroom, unlimited by geography, space, or time [2]. it is estimated that the total number of mobile phone users worldwide is double the number of internet users. one of the recent and significant changes in learning environment is the demand of mobility. the mobile phone becomes popular in the society and most of the people can afford the cost [3]. in addition, the exponential growth of wireless and mobile networks has brought vast changes in mobile devices, protocol development, standardization, network implementation, and user acceptance. mobile learning (m-learning), is defined as learning with mobile devices such as palms, personal digital assistant pda, cell phones, and any other handheld devices. mobile learning is the integration between mobile computing and elearning. mobile learning (m-learning), a natural extension of distance education, supported by wireless mobile technologies, is an emerging pedagogical learning model which requires new forms of teaching and learning. mobile technology can make instructors and students not to be restricted to a place and a time to teach and learn [4]. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ mahmood sami abd al-kareem al-khwarizmi engineering journal, vol. 7, no. 2, pp 47 54 (2011) 48 mobile learning through the use of wireless mobile technology allows anyone to access information and learning materials from anywhere and at anytime. as a result, learners have control of when they want to learn and from which location they want to learn [5]. 2. features of mobile learning there are four fundamental elements in mobile learning; learners, instructors, teaching contents and the teaching methods. all of them have the same feature of mobility. in comparison with the traditional learning methods, mobile learning has the following features [6]: 1mobility: as long as within the areas covering the mobile telecommunication network services, the learners can study anytime and anyplace. by the same token, the instructors can give their teaching information anytime and anyplace, and also can revise and renew the teaching resource database anytime and anyplace. 2real time: if learners need to get some knowledge, by using some technical methods, the learners can get that knowledge at once. 3interactive: by using mobile terminal instruments and the services of mobile communication, both learners and instructors can communicate in real time. 4virtualization: the instructors can create the virtual classroom, virtual instructors, and the learners can create the virtual class. the relationship between the instructors and the learners are dynamic and virtual. 5individuation: m-learning can provide individual services according to the learners’ needs and the features of the subjects. 3. technical support for mobile learning there are many technical and delivery supports to the mobile learning [7]: 13gp for compression and delivery method of audiovisual content associated with mobile learning. 2wireless fidelity (wi-fi) gives access to instructors and resources via internet. 3general packet radio service (gprs) is an always-on internet service, mobile data service, which provides a high speed connection and data transfer rates. 4bluetooth is a wireless short-range communications technology that can be used to transfer data between bluetooth-enabled devices. 5fourth-generation (4g) mobile telephone technology. every new generation of mobile handheld devices plays a different role in mlearning and makes change on m-learning business model. 44.. nmls requirements fig.1. main categories of technology adopted in nmls. the implementation of the nmls involves several development techniques that have been adopted and integrated to achieve a state of the art system. fig.1 illustrates the broad categories adopted in the design and implementation of the nmls. the nmls prerequisite the availability of the following technical requirements: 1) gprs and wi-fi: transport technologies are used to connect the mobile devices to the nmls website. 2) xhtml and java script: programming languages are used to design nmls website. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ mahmood sami abd al-kareem al-khwarizmi engineering journal, vol. 7, no. 2, pp 47 54 (2011) 49 3) tomcat 6.0 server: a hosting server of nmls website. 4) java server pages and java bean: programming languages are used to develop the nmls website. 5) mysql server and jdbc: mysql server is the program used to develop the database of nmls and java database connectivity (jdbc) is applied to access a mysql database. 6) smart phone is the device that is used to connect, browse and display the nmls website. 7) wap 2.0, sms and e-mail: delivery options to the nmls website. 8) smart phone: a device supporting 3gp, mp4 and mp3 streaming and enabling gprs data transfer. the operating system adopted for mobile device in the system is symbian. 5. framework of nmls the framework of nmls is illustrated in fig.2 the whole mobile learning system has three layers; they are data layer, business logic layer and the presentation layer. the presentation layer is built in the client, while the business logic layer and data layer are built in the server. a. data layer the data layer is located in the database server; it contains the data processing logic. its main task is to receive requesting information from the education resource web server, then complete the function of querying, refreshing and changing data in the database. thereafter, it returns the results to the education resource web server (business logic layer). b. business logic layer business logic layer is the main part of the whole nmls; the services of the mobile learning system are encapsulated in this layer. it has the responsibility to deal with the application requests of the presentation layer and to make logical estimation of the result. if the logical estimation is legal then the data is invoked by the system from database, data is processed and then the results are returned to the presentation layer. c. presentation layer the presentation layer is an interactive interface between users and the system. its responsibility is to deal with the dialog between users and system. fig.2. the framework of the nmls. 6. nmls users and functionality the nmls allows three different types of users to interact with the system according to given privileges. they are the administrator, instructor and student. it provides various services for each user. these users can login in the system in related identities, possessing a different operating authority and functions. 6.1. system for administrator the administrator subsystem plays an important role in keeping the system management. a huge amount of data must be update at the beginning of each semester. this subsystem provides the administrator with web-based services to manage the information of the nmls and other services provided by the system as instructor information management, student information management, local department administrator information management and college information management. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ mahmood sami abd al-kareem al-khwarizmi engineering journal, vol. 7, no. 2, pp 47 54 (2011) 50 6.1.1. administrate the instructors it comprises the following services: aview information of all instructors subscribed in the instructor subsystem. bdelete instructors information (subscription and registration); this could be due to subscription expiration time. cview result of questioner to instructors; this is used to calculate a final evaluation for all students in his /her study level. dinsert result of questioner to instructors; it is used to insert and calculate the final evaluation based on all students answers in his /her study level, as shown in fig.3. fig.3. insert questioner results. 6.1.2. administrate the students it comprises the following services: aview information of all students subscribed in the student subsystem. bdelete student information (subscription and registration); this can be due to subscription expiration or that the student has graduated. cview scores of all students in the online exam. this is useful in calculating the final score of each student, with relation to the student report score. dview scores reports of students. einsert students result to calculate the final score of each student dependent on the two previous services. 6.1.3. administrate the local departments administrators it comprises the following services: aview information of all local departments administrators subscribed in the administrator subsystem. bdelete information about local departments administrators due to expiration of subscription time. 6.1.4. administrate learning recourses it comprises the following services: aadministrate reports and sheets: this service allows the administrator to organize and integrate the uploading files (report and tutorial sheets) from instructors and students. badministrate mobile learning: this service allows the administrator to organize and integrate the uploading files (text, video and audio) from instructors and students. 6.2. system for instructor the instructor primary goal in the nmls is to provide a learning course (video, audio, pdf and tutorial sheet), evaluate students, send notes by sms or e-mail, add questions for the online exams, give students online exams and manage the database of questions. this system provides the instructor with web-based tools to manage the information and learning resources of the nmls. these tools provide the instructor by the following facilities: 6.2.1. enter questions to the online exams fig. 4. add questions service. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ mahmood sami abd al-kareem al-khwarizmi engineering journal, vol. 7, no. 2, pp 47 54 (2011) 51 this service allows the instructor to insert questions related to the online exams given to the students, as shown in fig.4. the instructor can add extra information as answers or mark the correct answer. 6.2.2. test report composition the service instructor can get students’ evaluation to the reports. additional information can be inserted with this report as student name, department and study level. 6.2.3. evaluation students by this service an instructor can view all answers of students related to the questions of the external knowledge service that he/she input to the students. this can be used to evaluate student according to his/her answer throughout the students evaluation service. 6.2.4. send notes and request to student the instructor can send some teaching notices, including exam alerts and test reminding to students. in addition the instructor can send some inquiries and alert messages to the administrators. to send sms to other nmls subsystems (administrators and students), the instructor fills the required fields .these fields are user name and password which are supplied by the sms gateway,(to) which indicates the phone number ,(text) which indicates the send message and the (from) that indicates the mobile learning system website sender. 6.2.5. database of question management aview previous questions: this service allows the instructor to review all the previous questions found in the database. the instructor can see other information related to questions as number of question, and probably the answers. bdelete previous questions: this service allows the instructor to delete previous questions related to online exams from the database. cscore of the exam: the instructor can review all his /her students’ score in a specific exam. the information related to the service includes student name, department, study level, date and time of the exam taken by students. 6.2.6. upload to mobile learning this service allows the instructor to call the following functions: aadd to learning courses: the instructor can upload the learning courses specific to each subject. first these courses are required to upload to the file server. thereafter the administrator of the instructor’s department can organize and link the learning course to the students. badd to video on demand: the instructor can upload video within a course. similarly, an upload to the file server is required. thereafter the administrator of the instructor’s department can organize and link the video to the students. cadd to audio on demand: the same as in (b) but this concerns uploading audio on demand. 6.3. system for student this is the system is originally intended for student. they can view and use the bulk of system services such as downloading the learning course (video, audio, pdf and tutorial sheet) carrying online exams and viewing college information. other services special to students are used to evaluate the learning operations. the students can inquire the administrator or instructor by email or question and answer (q&a) service. nmls provides many services to the student such as the following: 6.3.1. view general information college acourse list: student can review the course list in each department in the college and for different study levels. btime table: the student can review the time curricula table in each department in the college. cexamination list: this service allows the student to review the examination lists in each department in the college. 6.3.2. question and answer afaq: the student can review all frequently asked questions put in the nmls by instructors. bforum: the student can enter his/her inquiry and review other inquires and answers of his/her associate in the department. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ mahmood sami abd al-kareem al-khwarizmi engineering journal, vol. 7, no. 2, pp 47 54 (2011) 52 6.3.3. download learning courses it includes the following services: alearning courses: this service allows the student to view all learning course material provided by nmls. the student can follow the course online or download it into his/her mobile phone for later study at convenient time. additional information can be viewed .this concerns the topic title, department, study level and course number. bvideo on demand: this service allows the student to review all learning videos provided by nmls. the student can follow the course learning videos online or download them into his/her mobile phone for later study at convenient time. additional information can also be viewed. caudio on demand: the same as in (b) but this concerns downloading audio on demand. 6.3.4. evaluate instructor learning this service allows the student to evaluate the instructor level of teaching through the learning resource. the evaluation is carried on through answering questions related to the course, as shown in fig.5. the student must check the options: accepted, middle, good and excellent. this service allows each student to fill the form only once . fig.5. questioner form. 6.3.5. online exam after a student login in, he/she can do the exam, within a limited period specified by the instructor, as shown in the fig.6. the questions supported are of (fill in) and (multiple choices) types. fig.6. online exam service. 6.3.6. e-mail the student can send any suggestions or questions concerning the learned topic to the instructor. he can also send any inquiries to the administrator concerning his registration. thereafter, the student can receive the related answers. 7. discussion nahrain mobile learning system (nmls) compared with other related works has fulfilled certain advantages: 1. it comprises comprehensive learning services, requirements of teaching and management for different categories of users (administrator, instructor and student). 2. the nmls website has been publisher on the internet to guarantee that users can access the nmls to reach the learning services and management capability any time, any place. it facilitates the communication with the system platform allowing the exchange and sharing of data with users from existing resources on a server through the internet. the platform is embedded with the sms technology on mobile this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ mahmood sami abd al-kareem al-khwarizmi engineering journal, vol. 7, no. 2, pp 47 54 (2011) 53 phones, so it can exploits the functions of sms notification and reminding, which increases the flexibility of the system. 3. the nmls platform does not restrict to a special mobile device, but it allows different smart phones and pdas devices to access the services and learning resources through the internet. 4. the nmls platform does not require the installation and running of special programs in the mobile device to access the services and learning resources. however, all that it required is a mobile device supporting wap 2.0/xhtl, active mobile internet services gprs (gprs technology has been adapted to the nmls in the current research, because it is an available technology in iraq to connect to the internet by mobile devices) , wi-fi, and support of 3gp, mp4 and mp3 to play media content. 5. it does not restrict to the knowledge of specific topics but support versatile topics. 8. conclusions 1the nmls is based on wap 2.0 as a layer for connecting mobile learning applications with different mobile networks and operating systems without noticing mobility awareness. 2nmls platform is augmented with the sms technology on mobile phones. 3the main problem encountered the design and implementation of the nmls is the limited content arrangement in a very small mobile phone display. this problem is solved by dividing the users of the system into three categories (administrator, instructor and student). 4a problem of the low network bandwidth and cumbersome input of mobile phones is also encountered. bandwidth limitation has been solved by making the content of each page in the nmls website to have a minimum number of images. while the cumbersome input has been got through by providing each user of the nmls website navigators and links. 5nmls platform design and implementation has been based on the state of the art of programming environment and technical tools. 9. references [1] anna trifonova and marco ronchetti, “a general architecture to support mobility in learning”, proceedings of the ieee international conference on advanced learning technologies, pp 26-30, 2004. [2] qing li, “mobile enhanced learning: application model and practice”, proceedings of ieee international conference on computer science and software engineering, pp 694-697, 2008. [3] chi-hong leung and yuen-yan chan, “mobile learning: a new paradigm in electronic learning”, proceedings of the 3rd ieee international conference on advanced learning technologies, pp 76-80, 2003. [4] li he, jinhong fan and xiaoling fu, “research and application of a wap -based mobile learning system”, proceedings of ieee international conference on computer science and software engineering, pp 10411046, 2009. [5] mohamed ally, “mobile learning transforming the delivery of education and training”, au press, inc., february 2009. [6] yi jin, “research of one mobile learning system”, proceedings of the second ieee international conference on computer engineering and applications, pp 162-165, 2009. [7] alireza nasiri and guishi deng, “environmental factors influence on mobile learning business”, american journal of applied sciences, pp 1225-1234, 2009. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ 54 ، صفحة2، العدد 7مجلة الخوارزمي الھندسیة المجلد محمود سامي عبد الكریم 47 )2011( 54 (nmls) نقلمتالي میتعلالنھرین ال نظام ** ممتاز محمد علي* محمود سامي عبد الكریم جامعة النھرین رئاسة/ قسم الحاسوب والتعلیم المستمر * mahmood_sime@yahoo.com: البرید االلكتروني جامعة النھرین/ المعلومات ھندسةكلیة ** mumtaz_almukhtar@yahoo.com: البرید االلكتروني الخالصة ال ینظام تعلتضمن تخطیط وتصمیم وتطبیقی ا البحثل في ھذالعم ـ م نق مي ب ام (س رین ال نظ ل متاليم یَتعلالنھ ادر . ))nmls(نق ام مص ذا النظ زود ھ ی ن مدراء الو االساتذةمن قبل الطالب و ستخدم، التي یمكن َأن ت تعلیم كاملة دم م و یق ة وھ ف الجوال الل الھوات تعلم خ ى ال ال إل دیل فع ي لكتاالب ى . رون ز عل یرك یم یؤكد التفاعل بین المتعلم ومحتوى مرونة وویضیف قابلیة حركة ممارسة الَتعلم، ت . التعل ناف ال خدموامس ة أص ى ثالث نفون إل ام مص دراء و : نظ اتذة الم االس دیو (قتفاء تعلم الفصوِل اتعلق النظام بعلى مدى فذ تنیمكن َأن ةالتعلم المختلف نشاطات. طالبالو وتي وفی جیل ص غل .)نص وتس ام یش ل النظ ي اتممارس الك ف ات زود عملی ددة اال مَت عملیة التعلم، ی تعماال ع تعلم ال ال تس رض متدارة ال ل ، یع روریة دوات االانق اِل الض ي تص ت الت مح للمس ھم تخدمین االتس ع بعض ال م تص دیات الل المنت یرة ، البعض خ ائل القص ة الرس ائل و خدم ي الرس د إلكترون ة . بری تند nmls خط ة ةمس ى تقنی اتف لل 3gعل وال الھ ول وج ِق ال بروتوك تطبی تند nmls ھیكلیةإن . لنظام الذي تم اعتماده كأساس التصاالت ا)wap(السلكي ال ى ثالث ةمس ات ، ة عل ي طبق ة وھ رض طبق ة ط, الع لِ ال بق ي عم المنطق .بیاناتطبقة الو this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ <4d6963726f736f667420576f7264202d20d1edc7d620e6d4d1e6de20e6e1ede4c735372d203637> al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 14, no. 3, september, (2018) p.p. 5767 study the dissociation enthalpies for r134a clathrate hydrate in binary and ternary systems riyadh s. al mukhtar* shurooq t. al hemeri** lina w. mahmood*** *,**,***department of chemical engineering/ university of technology/ baghdad/ iraq ***email: lina.wheeb@yahoo.com (received 2 november 2017; accepted 14 january 2018) https://doi.org/10.22153/kej.2018.01.005 abstract in the present work the clathrate hydrate dissociation enthalpies of refrigerant r134a+ water system, and r134a + water + salt system were determined. the heat of dissociation of three types of aqueous salts solutions of nacl, kbr and naf at three concentrations (0.09, 0.17and 0.26) mol·kg−1 for each salt type, were enthalpy measured. the clapeyron equation was used tocalculate heat of dissociation of experimental data for binary and ternary system.in order to find the effect of compressibility factor on heat dissociation enthalpy, the study was conducted by using equation of state proposed by peng and robinson stryjek-vera (prsv). the obtained results of dissociation enthalpy for binary system were (143.8) kj.mol-1 without gas compressibility factor (z) and (136.08) kj.mol-1 with z where the variation between two values was (5.3%). for ternary system (r134a+ water +nacl) at three concentrations of this salt, the calculated values were in the range of (146.7 154.1) kj.mol-1without z and (138.02-145.14) kj.mol-1with z where the variation rang between two values was (5.8-5.7) %. the other two types of salts given similar results within (0.886 0.129) % deviation rang about nacl results without z and (0.818-0.149) % deviation rang with z values. keywords: clathrate, gas hydrate, hfc-r134a, dissociation enthalpy, ternary system. 1. introduction clathrate gas hydrates are ice-like components which the molecules of gas (name guest molecules) such as methane, carbon dioxide, nitrogen, refrigerant gas etc., are occluded in crystalline cells, consisting of water molecules (called cage molecules) retained by the energy of hydrogen bonds as shown in fig. (1). there are three types of gas hydrate structures of si, sii, and sh would form [1]. in spite of the gas hydrates can cause significant damage to the oil and gas industry due to their formation in numerous hydrocarbon production and processing operations, it has been well studied that they can used in different field, which named “positive” such as food processing, desalination, gas storage, cold storage systems, gas transportation, gas separation and carbon dioxide sequestration. the interest in gas hydrate related to its properties, such large heat of dissociation [2]. several of hydro chloro fluoro carbon (hcfc) and hydro fluoro carbon (hfc) refrigerants can form the hydrate in presence of water. because of proper melting temperature and fair heat transfer coefficients, hydrate of refrigerants has a good condition to use in energy storage at off-peak periods at power industry. r134a, r-141b and r-152a are the most common hfc and hcfc refrigerants that are used in hydrate researches [3]. riyadh s. almukhtar al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 5767 (2018) 58 fig. 1. structure of gas clathrate hydrate [1]. the dissociation of hydrate crystals is an endothermic process. for such a process to occur, heat of some form must be provided by an external source in order to break the bonds that are present in hydrate structure. it was observed that the dissociation process is analogous to that of the nucleate boiling phenomena [4]. the hydrate dissociation enthalpy is very important because their appearances the ability to use gas hydrate system at different process such as cold gas storage, desalination and gas separation. when the enthalpy dissociation for the system is high, the system can be used with good economic feasibility [5]. there are many literatures that deal with the experimental measurement for clathrate hydrate dissociation conditions ,such as aimee s. etal.,[6] studied the experimental dissociation conditions of clathrate at different temperature and pressure for ternary system consist of various refrigerant gases (r134a, r410a and r507),water and sucrose aqueous solution at different concentration of succor .and the hydrate dissociation conditions modeling by a thermodynamic relationships that based on the van der waals-solid solution theory where, the benefit of the dissociation data obtained is to use in design of aqueous solution separation process .sarshar m. etal.,[7] developed two correlations from the experimental data that obtained from another researches to calculate the enthalpy of clathrate hydrate dissociation in stat of simple i.e. a single component gas hydrate and mixed gas hydrates depending on the clausius-clapeyron equation. ngema p. etal.,[8] who performed the experimental measurements to conditions of gas hydrates dissociation were undertaken at range of temperatures and pressures , by using binary and ternary system which consist of refrigerant gases as (r134a, r410a, and r507) with salt aqueous solutions for various salt concentrations. then, modeling of the experimental dissociation data measured by using thermodynamic relationships and compared between two results. ngema p. etal.,[9] presented the experimental study for the gas clathrate dissociation conditions for systems comprising of different gas refrigerants (r134a, r410a, and r507) , water and calcium chloride at varying salt molarities . the clathrate dissociation conditions that obtained can be used in the design of industrial treatment of waste water and optimization conditions for desalination processes. 2. measurement methods of clathrate hydrate dissociation enthalpy (δhd) the heat of hydrate dissociation (δhd) can be identified through two methods direct and indirect, in the direct method the calorimetric was used to measure the heat of dissociation. lin etal.,[10], martínez etal.,[11] and delahaye etal.,[12] measured the heat of dissociation for carbon dioxide hydrate by calorimetric method. dongyoung l. etal.,[13] who measured the experimental values of dissociation enthalpies for binary system pure gas refrigerant r-134a hydrate and the ternary system hfc-134a hydrates in the presence of nacl by differential scanning calorimeter (dsc) method. to used their obtained data in application of desalination processes. a second method (indirect) which used to calculate the heat of dissociation (δhd) by applied clausiusclapeyron equation for threephase (liquid water, hydrate, vapour) of hydrate dissociation equilibrium data of hydrate forming systems. this method is the easier and simpler method to estimate the enthalpy of dissociation. using the clausiusclapeyron equation which is stated below [14]: ���� ���/� = ∆� �� …(1) where: t is temperature, p is the pressure, ∆hd is the heat of dissociation, r is the universal gas constant and z is the gas compressibility factor. khaliket et al., [15] mentioned that the heat of dissociation for carbon dioxide hydrate is calculated by indirect method.in his work, the compressibility factor z, was determined from pitzer’s equation. furthermore, it was also shown that the presence of electrolytes affects to the dissociation heat (∆hd) of the clathrate hydrate. riyadh s. almukhtar al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 5767 (2018) 59 hashemi h. et al., [16] declared that the (∆hd) of the refrigerant hydrates are a critical property of a cold storage medium, which calculated for refrigerants r404a, r406a, r410a, r507c and r407c at different temperatures by the indirect method in which z is the gas compressibility factor obtained using peng and robinson stryjekvera (prsv) equation of state. graydon k., [17] calculated the enthalpies of the methane hydrate dissociation by direct analysis using the clapeyron equation. khalik m. etal., [18] estimated the dissociation enthalpies of pure co2 hydrate and mixed co2 and r134a hydrate by indirect measurement using the clausius– clapeyron equation. a significant increase was observed for dissociation enthalpies of mixed hydrates at different concentrations of carbon dioxide. qazi n. etal.,[19] pointed out in his work using of clausius-clapeyron equation to determine the dissociation enthalpies of pure ch4 and pure carbon dioxide gas clathrate depending on experimental data at various pressure and temperature. shicai s. etal., [20] calculated an important thermal parameter in clathrate was the dissociation enthalpies for methane hydrate in various salt solutions by the clausius-clapeyron equation. sabil k. et al [21] calculated the heat of dissociation for carbon dioxide hydrate in the presence of electrolytes by indirect method clausius–clapeyron equation. where, the compressibility factor was determined from pitzer’s equation. 3. cubic equation for compressibility factor (z) calculation to calculate the compressibility factor (z) by peng–robinson equation of state which later modified by javanmardi et al. [22]: p= � � � �� �� ��� �� …(2) peng–robinson equation which is one of the cubic equation of the state given by [23]: z= � � �� � � � ������� �� ...(3) where z= � � � � …(4) tr= � �� …(5) pr= � �� …(6) a(t)=0.457235������ �� α(t) …(7) b=0.077796( � �� �� ) …(8) the expression proposed by smith h.etal., [24] is used for the α: α(t)=(1+k(1−tr))2 …(9) k=0.37464+1.54226w−0.26992w2 …(10) equation (3) rearranged to give [25]: z3+βz2+γz+δ=0 …(11) a= a p ���� …(12) b= � � � � …(13) β=b-1 …(14) γ=a-3b2-2b …(15) δ=b3+b2-ab …(16) the following two values are first calculated [26]: q= �� ! " …(17) r= ��� "�!��#$ %& …(18) θ = arccos . / 01� 2 …(19) then, the three roots are given by: z1=-2q1/2cos( 3 -( � …(20) z2=-2q1/2cos( 3��4 -( � …(21) z3=-2q1/2cos( 3�&4 -( � …(22) in present study, r-134a refrigerant was used in the hydrate formation for binary system (r134a and water) and ternary system (r-134a, water, salt). three types of salts nacl, kbr and naf at three concentrations (0.09, 0.17 and 0.26) mol·kg-1 for each type of salt, were used in ternary system. enthalpy conditions of dissociation to r-134a refrigerant gas hydrate for binary and ternary systems were measured using a conventional isochoric pressure search method. 4. isochoric pressure search method in the isochoric operation preliminary system temperature and pressure is set in the hydrate instability region, as in fig.(2).at point a ,was the initial point at which the temperature of the cell is lowered and leading the pressure of the cell to decrease to point b. at point b, the gas clathrate begins to form and the pressure immediately decreases further to reach the point c. at this point, the temperature is began increased and also the pressure increase because the hydrate crystals was dissociate. when the clathrate hydrates are dissociated, all the gas is released from the hydrate crystals and the temperature and pressure are recorded as the dissociation conditions. the isochoric method was independent of visual observation and since riyadh s. almukhtar al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 5767 (2018) 60 the process is a closed system, enables to operate at higher pressures [27]. fig. 2. isochoric pressure search method [27]. 5. experimental work materials: table (1) presents the information about the materials which used in the present study. table1, show the details of different salts, refrigerant and water which are used in this study. materials chemical formula molecular weight (g/mol) provider phase distilled water h2o 18 laboratory liquid r134a cf3ch2f 102.03 public market gas sodium chloride nacl 58 fiuka germany solid potassium bromide kbr 119.002 himedio india solid sodium fluoride naf 41.99 fiuka germany solid apparatus aschematic diagram of the experimental setup is shown in fig. (3). the experimental cell was cylindrical glass with inner and outer diameter (135 and 145) mm respectively, the cell height was 150 mm, the effective volume approximately 1500 cm3. the cell was equipped with three resistance thermocouples (k-type) located at different levels, the thermocouples connected to interphase type max6675 temp module arduino, which in connected to computer to records temperatures for each run. the cell also equipped a mixer type heidolph rzr 0, there was pressure gaugeconnected to the cell type. fig. (1) shows the main features of the experimental rig. fig. 3. schematic flow diagram for the experimental unit: (1) r134a refrigerant cylinder;(2) needle valve;(3) gas compressor;(4) condenser;(5)accumulator ;(6)experimental cell;(12) gas collection cylinder ;(7)mechanical stirrer; (8)flow meter;(9)pressure gauges;(10) thermocouples(k-type);(11) rotary valve ;(13) drain valve ;(14) chiller;(15)interface system;(16) computer. riyadh s. almukhtar al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 5767 (2018) 61 fig. 4. the apparatus. experimental run the dissociation conditions of the gas hydrate was at isochoric pressure method. the experiment started by filling the cell with distilled water to clean the cell, then it was evacuated to a pressure of (-0.67) cmhg gauge for of 30 min. about 250 ml pure water or (nacl, kbr, naf) aqueous solution at (0.09, 0.17and 0.26) mol.kg-1 for each salt charged into the cell. the cell was surrounded by a water jacket which supplied from water circulation bath controlled temperature. the residual air in the cell was evacuated, after that the cell was pressurized with refrigerant gas (r134a) to the desired pressure. and mixer stirred turn on into the cell to ensure homogenous mixing until stabilization of the measured temperature and pressure.then, the temperature was slowly decreased to facilitate the nucleationof gas hydrates visually. the pressure was decrease gradually with increasing of hydrate formation till reach fixed value. after the formation step, the water bath temperature increased slowly for hydrate dissociation step which causes increased the pressure inside the cell until reach to the initial conditions of pressure and temperature. fig.(5) provides an example for clarification the isochoric method for hydrate formation and disassociation curves obtained in this study for the r134a and water system. the region of hydrate formation represented by cooling curve (a) when, it is noted that the temperature readings start decreasing step by step to a certain temperature and a sharp decrease of pressure because of the hydrates formation as a result of the solubility of r134a in water. then, it stabilizes at constant pressure, after these point the pressure and temperature increased as the dissociation region represented by heating curve (b). the intersection between the cooling (a) and heating (b) curves indicates the equilibrium transition from (hydrate + liquid + gas) to (liquid + gas) and that was called as the hydrate equilibrium point or dissociation point where the pressure and temperature are at equilibrium. fig. 5. pressure vs. temperature equilibrium curves for r134a water system at hydrates stability conditions. fig. 6. hydrate formation and disassociation for the r134a and water system. riyadh s. almukhtar al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 5767 (2018) 62 6. results & discussion dissociations data of r134 refrigerant clathrate hydrate the dissociation data for [1, 1, 1, 2tetrafluoroethane (r134a) (1) +water (2)] in this study was measured by the experimental apparatus and compared with literatures. according to the experimental results in fig.(7) was observed equitable amount of scatter when comparing the data of this work to the literatures [3],[8] and [28] for the same binary system. in a present work the hydrate dissociation pressure is lower than that of literatures [3] and [28] and identical with literature [8]. while the hydrate dissociation temperature of this investigation higher than that of literatures [3] and [28] and approximately convergent with literature [8]. because of, those most light molecules such as methane, ethane, propane, normal butane, nitrogen, carbon dioxide and hydrogen sulfide will form the hydrates under specific conditions of high pressure and low temperature. but the use of refrigerants to form gas hydrate enable hydrate formation at near ambient conditions compared to hydrate formation using hydrocarbons [16]. fig. 7. experimental data for r134a hydrate dissociation phase diagram: ● this work , ▲ literature [3]; ♦ literature [8]; ■ literature [28] ternary system r134a+water dissociation date in presence salt: the presence of the salt in the refrigerant water system causes depression of water freezing point and inhibition water from vaporizing this is because of the stronger interactions between water and salt. the highest and lowest hydrate dissociation points measured were dependent on the freezing point and vapour depression data [29]. figs. 8,9,10 show hydrate dissociation for ternary system with three types of salt nacl, kbr, naf with three different concentrations for each type of salt (0.09, 0.17 and 0.26) mol·kg−1. hydrate dissociation conditions were measured for ternary systems to examine effect of the salt concentration on dissociation conditions and stability. from three figs. (8,9and 10) it is obvious that increasing salt concentration in the aqueous solution , causes to reduce hydrate dissociation temperature that may be explained because of refrigerant r134a solubility decreases with increasing salt concentration as the interactions between the salt ions and water molecules are stronger than the interactions between water and dissolved gas refrigerant r134a.thetemperature low for hydrate formation reasoned by the particular salt which called hydrate inhibition strength. the hydrate formation temperature is affected by the type of salts presence in the hydrate forming system because the different types of salts have different hydrate inhibition strength [13], [15].in the range of the study, it was founded that naf salt has relatively the least hydrate inhibition strength while nacl and kbr salts are the the highest inhibition strength. therefore, naf salt solution has increase in the hydrate dissociation temperature compared to the other two solutions of salts as shown in fig. (10). the hydrate inhibition strength on an electrolyte depends on the ionic size. when the ion radius decrease, the bond between the water molecules and the ions becomes stronger since na+(0.98 å) has a smaller ionic radius compared to k+ (1.38 å), therefore na+ should have a stronger inhibiting effect for hydrate formation [30]. fig. 8. r134a hydrate dissociation data for the r134a water nacl system this work: ■without salt, ■ 0.09 mol/kg, ▲0.17 mol ̸ kg● 0.26 mol/kg. riyadh s. almukhtar al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 5767 (2018) 63 fig. 9. r134ahydrate dissociation conditions for ternary system with kbr salt of this work: ■inabsence salt, ■ 0.09 mol ∕ kg, ▲0.17mol.kg1●0.26mol ∕ kg. fig. 10. r134a hydrate dissociation conditions in presence nafsalt in present studywork: ■ without salt, ■ 0.09 mol ̸ kg, ▲0.17mol ̸ kg●0.26 mol ̸ kg the plot of ln p vs. 1 ∕ t for dissociation data of the of present work to obtain the heat of dissociation forr134a hydrate was shown in fig. (11). fig. 11. dissociation data of r134 hydrate, represented by ln p vs. 1/tplot. from figs.(11, 12 and 14) can observe the good linear relationships from plot of (lnp) versus (1/t) for hydrate refrigerant of binary system only and also in presence nacl and naf at various concentrations, which show more linear than r134a in presence kbr at different concentration that shown in fig.(13). fig.12. the logarithms of the dissociation pressures (ln p) versus (1/t) along r134a(v)− liquid water (lw)−hydrate (h) in the presence and absence nacl coexistence lines♦without salt;■0.09 mol ̸ kg;▲0.17 mol ∕ kg;●0.26 mol ∕ kg. in the present study and based on available experimental data for enthalpy of hydrate dissociation when pure water or at presence of sodium chloride shows ions impact on the enthalpy of hydrate dissociation, because at all three concentrations of sodium chloride in the aqueous solution, the enthalpies of dissociation of the gas hydrate are higher than of pure water. however, khalik b. et al., [15] has found that at 3mol% of sodium chloride the enthalpy of the co2 hydrateis higher than that of pure water. that is because the presence of electrolyte in the system requires a higher energy to form hydrate and similarly, a higher energy to dissociate the hydrate formation. although this agreement may be valid to a high concentration of sodium chloride, it is not valid for an aqueous solution with low concentrations of sodium chloride. riyadh s. almukhtar al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 5767 (2018) 64 fig. 13. the logarithms of the dissociation pressures (ln p) versus (1/t) along r134a (v)−water (lw) −hydrate (h) in the presence and absence kbr coexistence lines♦ no salt; ■ 0.09 mol ̸ kg; ▲0.17 mol ∕ kg; ●0.26 mol ∕ kg. fig.(14): the logarithms of the dissociation pressures (ln p) versus (1/t) along r134a(v)−water (lw) −hydrate (h) in the presence and absence naf coexistence lines♦ without salt; ■ 0.09 mol ∕ kg; ▲0.17 mol ∕ kg;● 0.26mol ∕ kg. when compare calculated δhd with compressibility factor z and without compressibility factor (see table 2), the obtained δhd with compressibility factor z seems more close to the literature data (see table 3), while δhd without compressibility factor are far away from literature. the different between this study values with other literature as a result of the different equation of state(eos) used to estimate z. the enthalpy of dissociation of the r134a hydrate at three concentrations of sodium chloride in the aqueous solution is higher than that of pure water in the estimated value. in the present work, the enthalpy of dissociation of r134a in presence two different electrolytes, namely potassium bromide (kbr) and sodium fluoride (naf) in the aqueous solution increases with increasing concentration of the electrolyte from 0.09 to o.26 mol.kg-1. the table (2) and equation (23) show dissociation heat deviation was about (5-7%), this percentage is important when consider the ability of refrigerant use in cool storage application also, this deviation must be considered for desalination process as heat of dissociation of aqueous salt supplied to the systems (endothermic). le h. [28] suggested that the presence of electrolyte in the system requires a higher energy to form hydrate and similarly, a higher energy to dissociate the hydrate formation. the deviations between the enthalpies with calculate z and without calculate z shown below: deviation = �∆56 789:;<9 = �∆56 789: = �∆56 789:;<9 = * 100% …(23) where (δhd) without z is the enthalpy of systems without calculates the compressibility factor z, and the (δhd with z) is the enthalpy of systems depends on the compressibility factor z. it can be seen from table (2) that the deviationof the enthalpy with z compares with the enthalpy without z in presence and absence different salts at different concentrations. table 2, enthalpy of dissociation δhd of different systems of r134a refrigerant hydrate for various salts. system δhd(kj/mol)(ideal) δhd(kj/mol) *z(real) deviation% water+r134a 143.8 136.08 5.3 water+r134a+0.09mol∕kgnacl 146.7 138.02 5.9 water+r134a+0.17mol∕kgnacl 152.6 143.77 5.7 water+r134a+0.26mol∕kgnacl 154.1 145.14 5.8 water+r134a+0.09mol∕kg kbr 145.4 136.89 5.8 water+r134a+0.17mol∕kg kbr 152.4 143.6 5.7 water+r134a+0.26mol∕kg kbr 154.3 145.35 5.8 water+r134a+0.09mol∕kg naf 146.7 137.4 6.3 water+r134a+0.17mol∕kg naf 153.1 144.28 5.7 water+r134a+0.26mol∕kg naf 153.6 144.72 5.7 riyadh s. almukhtar al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 5767 (2018) 65 table 3, experimental and literature data of the enthalpies of dissociation for r134a+water binary system. system δhd(kj/mol) literature r134a+water 136.08 this work 124.1 liang et al,[31] 124.1 mohammadi et al., [32] 143.48 casandra [33] 7. conclusion 1. the hydrate dissociation conditions were reported for binary system; r134a+water and ternary system; r134a+water+salt for three types of salt at three concentrations (0.09, 0.17and 0.26) mol.kg-1. 2. the isochoric method was applied to measurement the conditions of hydrate dissociations in the binary and the ternary systems. 3. the presence of nacl, kbr and naf salts in the gas hydrate system reason shifted the dissociation temperatures of refrigerant hydrate to lower values. 4. the heats of dissociation for r134a clathrate were determined by the indirect method (clapeyron equation) depended on the measured dissociation data for binary system and also in presence different salts for various concentrations. 5. from δhd results that were obtained for r134a hydrate system, may note that heat of dissociation with high accuracy by clapeyron equation include compressibility factor z that obtained by relationship of peng robinson from the results that obtained for δhd without compressibility factor. notation tr reduced temperature pr reduced pressure r gas constant v molar volume tc critical temperature pc critical pressure ω acentric factor 8. references [1] lv q., li x., chen z. and feng j.," phase equilibrium and dissociation enthalpies for hydrates of various water-insoluble organic promoters with methane",journal of chemical engineering,58, pp.3249-3253, 2013. 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[29] hashimoto s., makino t., inoue y. and ohgaki k., " three-phase equilibrium relations and hydrate dissociation enthalpies for hydrofluorocarbon hydrate systems: hfc-134a, -125, and -143a hydrates", j. chem. eng. data, 55, 4951– 4955, 2010. [30] hamed h.,” application of gas hydrates in cold storage technology: experimental study and thermodynamic modeling”, m.sc. thesis, university of kwazulu-natal, september 2015 [31] liang, d. guo, k. wang, r. fan, s., “fluid phase equilib.”, pp.187-188 ,2001. [32] mohammadi, a. h.; richon, d.,"phase equilibria of methane hydrates in the presence of methanol and/or ethylene glycol aqueous solution".ind. eng. chem. res.,49, pp.925−928, 2010. [33] cassandra, dr. a. h. mohammadi petticrew, prof. d. ramjugernath, dr. p. naidoo, prof. ch. buckley," an investigation into the use of fluorinated hydrating agents of industrial waste water", ph.d.thesis, university of kwa-zulu natal, 2011. )2018( 57-67، صفحة 3د، العد14دجلة الخوارزمي الهندسية المجلم رياض صادق محمد 67 بالنظامين الثنائي الرطب) r134aغاز التبريددراسة المحتوى الحراري لتفكك الكالثريت (ل الثالثيو **شروق طالب رمضان الحميري *المختار رياض صادق محمد ***لينا وهيب محمود الجامعة التكنولوجية/ العراق/ بغداد*،**،***قسم الهندسة الميكانيكية/ lina.wheeb@yahoo.com :البريد االلكتروني*** الخالصة +ماء + r134a+ماء) والنظام الثالثي المتكون من (غازالتبريد r134aالبحث تم حساب حرارة التفكك للنظام الثنائي المتكون من (غازالتبريدفي هذا ، ٠٬٠٩تراكيز( األمالح هي كلوريد الصوديوم، بروميد البوتاسيوم وفلوريد الصوديوم عند ثالثة محاليل لثالثة أنواع منحرارة التفكك ملح). حيث تم حساب الدراسة للتفكك. وحصيلةللنظام الثنائي والثالثي اعتمادا على البيانات العملية التفكك حساب حرارة كالبيرون استخدمت ل. معادلة كغم\مول )٠٬٢٦، ٠٬١٧ ) ١٤٣٬٨ناتج النظام الثنائي هو( التفكك. وكان) على حرارة z( الغاز ) أليجاد تأثير معامل انضغاطpeng and robinson(ـ تمت باستخدام معادلة الحالة ل ) %. معدل القيم المحسوبة للنظام الثالثي بوجود كلوريد ٥٬٣مول علما أن االنحراف بين القيمتين هو(\كجول )١٣٦٬٠٨( zوبوجود zمول بدون \كجول مول وكان معدل االنحراف \) كجول ١٤٥٬١٤-١٣٨٬٠٢( zمول ومع \) كجول ١٥٤٬١-١٤٦٬٧بالمدى ( zالصوديوم عند التراكيز الثالثة للملح من دون )% ٠٬١٢٩ -٠٬٨٨٦( نتائج مشابهة لنتائج ملح كلوريد الصوديوم بمعدل انحراف ان من االمالح لهمااآلخر ان) %. النوع٥، ٧ ٥، ٨بين القيمتين هو ( ).z( االنضغاطمعامل % عند أدخال قيم )٠٬١٤٩-٠٬٨١٨ومعدل انحراف ( zبدون al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 8, no. 1, pp 76 85 (2012) natural convection in trapezoidal enclosure heated partially from below ahmed w. mustafa* ihsan ali ghani** *department of mechanical engineering/college of engineering/university of tikrit **department of mechanical engineering/college of engineering/university of al-mustansiriya *e-mail: ahmedweh@yahoo.com **e-mail: iaghani68@yahoo.com (received 20 july 2011; accepted 22 november 2011) abstract natural convection in a trapezoidal enclosure with partial heating from below and symmetrical cooling from the sides has been investigated numerically. the heating is simulated by a centrally located heat source on the bottom wall, and four different values of the dimensionless heat source length, 1/5, 2/5, 3/5, 4/5 are considered. the laminar flow field is analyzed numerically by solving the steady, two-dimensional incompressible navier-stokes and energy equations. the cartesian velocity components and pressure on a collocated (non-staggered) grid are used as dependent variables in the momentum equations discretized by finite volume method; body fitted coordinates are used to represent the trapezoidal enclosure, and grid generation technique based on elliptic partial differential equations is employed. simple algorithm is used to adjust the velocity field to satisfy the conservation of mass. the range of rayleigh number is (103≤ ra ≤105) and prandtl number is 0.7. the results show that the average nusselt number increases with the increases of the source length. keywords: natural convection, trapezoidal enclosure, finite volume. 1. introduction in recent years, an ever-increasing awareness in thermally driven flows reflects that fluid motions and transport processes generated or altered by buoyancy force are of interest due to the practical significances in many fields of science and technology. as a result, this subject is currently studied in diverse areas of meteorology, geophysics, energy storage, fire control, studies of air movement in attics and greenhouses, solar distillers, growth of crystals in liquids, etc. iyican and bayazitoglu (1980) investigated natural convective flow and heat transfer within a trapezoidal enclosure with parallel cylindrical top and bottom walls at different temperatures and plane adiabatic side walls. the flow features in trapezoidal enclosures are predicted using data collected for rectangular enclosures. peric (1993) studied natural convection in a trapezoidal cavities with a series of systematically refined grids from 10 x 10 to 160 x 160 control volume and observed the convergence of results for grid independent solutions. kuyper and hoogendoorn (1995) investigated laminar natural convection flow in trapezoidal enclosures to study the influence of the inclination angle on the flow and also the dependence of the average nusselt number on the rayleigh number. natarajan etc. (2008) investigated natural convection within a trapezoidal enclosure with uniform and nonuniform heating of the bottom wall of the enclosure, they found that the non-uniform heating of the bottom wall produces greater heat transfer rate at the center of the bottom wall than uniform heating case for all rayleigh numbers but average nusselt number shows an overall lower heat transfer rate for non-uniform heating case. basak etc.( 2009) investgated laminar natural convection inside trapezoidal with uniform and non-uniform heated bottom wall ,insulated top wall and isothermal sides with inclination angle mailto:ahmedweh@yahoo.com mailto:iaghani68@yahoo.com ahmed w.mustafa al-khwarizmi engineering journal, vol.8, no.1, pp 7685 (2012) 77 (40 o , 30 o , 0 o )and for range of rayliegh(10 3 ≤ ra ≤10 5 ) and prandtle number( 0.026 ≤ pr ≤ 1000).they found that the average heat transfer does not vary significantly with angles for nonuniform heating of bottom wall . it is seen from the literature that no attempt has been made for the detailed calculations of local and average nusselt numbers on a natural convection flow within a trapezoidal enclosure for partial heating. symmetrical cooling from the sides is expected to be an efficient cooling option, while partial heating at the lower surface simulates the electronic components such as chips. the present study deals with a natural convection flow within a trapezoidal enclosure where the bottom wall is partially heated and vertical walls are cooled by means of a constant temperature bath whereas the top wall is well insulated. 2. problem formulation consider the motion of a viscous fluid within a trapezoidal enclosure with equal base length and height, l = h with the left wall inclined at an angle  = 30 o and with the y-axis as shown in figure (1a). the bottom wall has a centrally located heat source of length (e) which is assumed to be isothermally heated at temperature (th), the sidewalls are isothermally cooled at a constant temperature (tc); while the bottom surface, except for the heated section, and the upper wall is considered to be adiabatic. the fluid properties are assumed constant except for the density variation which is treated according to boussinesq approximation. the present flow is considered steady,laminar, incompressible and two-dimensional. the viscous incompressible flow and the temperature distribution inside the enclosure are described by the navier–stokes and the energy equations, respectively (bejan [6], 1993): 0      y v x u …(1)                     2 2 2 21 y u x u v x p y u u x u u  …(2) )( 1 2 2 2 2 cttg y v x v v y p y v v x v u                        …(3)                  2 2 2 2 y t x t y t v x t u  …(4) the governing equations were transformed into dimensionless forms upon incorporating the following non-dimensional variables (bejan[6], 1993): ,pr,, ,,,, 2 2           ph p tt tt vh v uh u h y y h x x ch c   2 3 pr   httg ra ch  …(5) where x and y are the dimensionless coordinates measured along the horizontal and vertical axes, respectively; u and v are the dimensional velocity components along xand y axes, and  is the dimensionless temperature. the dimensionless forms of the governing equations under steady state condition are expressed in the following forms: 0      y v x u …(6)                       2 2 2 22 pr y u x u x p y uv x u …(7) prpr 2 2 2 22 ra y v x v y p y v x uv                       …(8)                    2 2 2 2 yxy v x u  …(9) fig.1a. schematic diagram of the physical system. g h y x tc tc adiabatic source at th adiabatic  l e ahmed w.mustafa al-khwarizmi engineering journal, vol.8, no.1, pp 7685 (2012) 78 x y 0 0.5 1 1.5 2 0 0.2 0.4 0.6 0.8 1 3. boundary conditions boundary conditions can be summarized by the following equations: bottom wall  1 0 0,0                       sourceforand n portionadiabaticforbut n p vuwallallfor top wall 0,0,0        n p n vu  left wall 0,0     n p vu  right wall 0,0     n p vu  where n is the normal direction on the walls. 4. grid generation and numerical solution the set of conservation equations (6-9) can be written in general form in cartesian coordinates as   s yyxxy v x u                             )()( …(10) where  is the effective diffusion coefficient,  is the general dependent variable, s is the source term. the continuity equation (6) has no diffusion and source terms; it will be used to derive an equation for the pressure correction. the grid generation scheme based on elliptic partial differential equations is used in the present study to generate the curvilinear coordinates. in this method, the curvilinear coordinates are generated by solving the following elliptic equations, (thompson etc.[7], 1985)                          02 02 2 22 2 2 2 22 2 2             yyy xxx …(11) where α,,  are the coefficients of transformation. they are expressed as 22 22 ,,                                                             yx yyxxyx …(12) the grid generation for the trapezoidal enclosure for number of control volume (30 x100) is illustrated in figure (1b). fig.1b. gird generation for number of control volumes mxn= 30x100 equation (10) can be transformed from physical domain to computational domain according to the following transformation  yx ,  ,  yx ,  , the final form of the transformed equation can be written as:                        js j j gg                                                   21 …(13) where g1 and g2 are the contra variant velocity components, j is the jacobian of the transformation, on the computational plane. they are expressed as )( ,, 21                         xyyx j y u x vg x v y ug …(14) ahmed w.mustafa al-khwarizmi engineering journal, vol.8, no.1, pp 7685 (2012) 79 the transferred equation (13) is integrated over the control volume in the computation domain. the convective terms are discretized by using hybrid scheme, while the diffusion terms are discretized by central scheme. simple algorithm on a collocated nonorthogonal grid is used to adjust the velocity field to satisfy the conservation of mass. since all variables are stored in the center of the control volume, the interpolation method is used in the pressure correction equation to avoid the decoupling between velocity and pressure as in rhie and chow (1983). in order to consider the effect of the cross derivatives and to avoid solving a nine diagonal matrix of the pressure-correction equation, the cross derivatives are calculated by the approximate method of wang and komori (2000). the resulting set of discretization equations are solved iteratively using the line-byline procedure which uses the tri-diagonal matrix algorithm (tdma). the convergence criterion is that the maximum residuals in all equations fall below 10 -4 . for further information, numerical details can be found in ferziger and peric (1996). 5. grid independence test computations have carried out for three selected grid sizes (i.e., 80 × 30, 100 × 40, and 100 ×50). figure (2) shows local nusselt number distribution along the hot bottom wall for ra = 10 6 and e = 3/5. results for the selected grid sizes show very good agreement with each other. medium grid (100 × 40) is presented throughout this paper. 0.20 0.40 0.60 0.80 x 0.00 5.00 10.00 15.00 20.00 25.00 n u mxn=80x30 mxn=100x40 mxn=100x50 fig.2. grid independence test for local nusselt number for ra = 10 5 , e =3/5 . 6. validation the model validation is an essential part of a numerical investigation. hence, the present numerical results are compared with the numerical results of tanmay basak etc. (2009), which were reported for laminar natural convection heat transfer in a trapezoidal enclosure heated isothermally from below while the other vertical walls are maintained at constant cold temperature and the top wall is well insulated, they solved the governing equations by using finite elements method. the comparison is conducted while employing the following dimensionless parameters: ra = 10 5 , pr = 0.7 and trapezoidal angle  = 30 o . excellent agreement is achieved, as illustrated in figure (3), between the present results and the numerical results of tanmay basak etc. (2009).for the local nusselt number distribution along the bottom wall. 0.00 0.20 0.40 0.60 0.80 1.00 x 0.00 10.00 20.00 30.00 40.00 n u tanmay basak etc. (2009) present study fig.3. comparison of the present study with the result of tamnay basak etc.(2009) for local nusselt number on the bottom wall of trapezoidal enclosure for ra =10 5 , pr = 0.7 and trapezoidal angle ( =30 o ) 7. results and discussion figures 4,5,6, and 7 show the effect of changing rayleigh number for 10 3  ra  10 5 and the effect of changing the dimensionless length of the heat source for e = (e/l) = 1/5, 2/5, 3/5, and 4/5 respectively, as in aydin and yang[11], (2000). owing to the symmetrical boundary conditions on the side walls, the flow and temperature fields are symmetrical about the midlength of the enclosure. the symmetrical boundary conditions in the vertical direction result in a pair of contour rotating cells on the left and right halves of the enclosure. ahmed w.mustafa al-khwarizmi engineering journal, vol.8, no.1, pp 7685 (2012) 80 -0 .3 5-0 .3 -0 .2 5 -0 .2 -0 .1 5 -0 .1 -0 .1 -0.05 -0.05 0.05 0.1 0. 15 0.2 0.25 0 .3 0.4 -3 -2.5 -2 -1 .5 -1 -1 -0 .5 -0 .5 0.5 0.5 1 1. 5 2 2.5 3.5 -10 -8 -6 -4 -4 -2 2 2 4 6 6 8 1 0 12 fig.4. isotherms (left) and streamlines (right) for e = 1/5 and (a) ra =10 3 , (b) ra = 10 4 , (c) ra = 10 5 . fig.5. isotherms (left) and streamlines (right) for e = 2/5 and (a) ra =10 3 , (b) ra = 10 4 , (c) ra = 10 5 . -2 -1.5 -1 .5 -1 -0.5 0. 5 0.5 1 1.5 1.52 3 -8 -6 -4 -2 -2 2 2 4 6 6 8 -0.3 -0 .2 5-0.2 -0.15 -0.1 -0.1 0 .0 5 -0.05 0.05 0. 05 0.1 0. 1 0.15 0.2 0. 25 ahmed w.mustafa al-khwarizmi engineering journal, vol.8, no.1, pp 7685 (2012) 81 -0.45 -0.4 -0.35 -0.3 -0 .2 5 -0.2 -0 .2 -0.15 -0 .1 -0 .1 -0.05 -0.05 0 .0 5 0. 05 0 .1 0.15 0. 15 0 .20 .2 5 0 .3 0 .4 0 .4 5 -3.5 -3 -2.5-2 -1 .5 -1 -1 -0 .5 -0.5 0.5 0.5 1 1 1.5 2 2 2 .5 3 3 .5 -1 0 -8 -8 -6-4 -4 -2 -2 2 2 4 6 6 8 12 -0 .4 -0 .3 -0 .2 5 -0 . 2 -0 .1 5 -0 .1 -0 .1 -0 .0 5 -0 .0 5 0.05 0.1 0.15 0 .2 0 .2 5 0 .3 0.4 -4 -3 .5 -3 -2 .5 -2 -1 .5 -1 -1-0 .5 -0 .5 0.5 0.51 1 .5 1.5 2 2 .5 3 3 .5 -1 2 -10-8 -8 -6 -4 -2 -2 2 2 4 4 6 8 8 10 12 fig.6. isotherms (left) and streamlines (right) for e = 3/5 and (a) ra =10 3 , (b) ra = 10 4 , (c) ra = 10 5 fig.7. isotherms (left) and streamlines (right) for e = 4/5 and (a) ra =10 3 , (b) ra = 10 4 , (c) ra = 10 5 . ahmed w.mustafa al-khwarizmi engineering journal, vol.8, no.1, pp 7685 (2012) 82 7.1. effect of rayleigh number figure 4(a-c) shows the streamlines and isotherms pattern obtained for (e = 1/5). for ra = 10 3 , the circulation inside the enclosure is so weak that the viscous forces are dominant over the buoyancy force. at ra= 10 4 the intensity of the circulation insides the enclosure increases as shown in (figure 4b). as rayleigh number increases to 10 5 , the buoyancy driven circulation inside the cavity also increases as seen from greater magnitudes of the stream functions (fig. 4c). it is interesting to observe that the stream function contours near the walls tend to have neck formation due to stronger circulation at higher ra which contrasts the circulation patterns at smaller ra as seen in (fig. 4a). due to stronger circulation, the isotherms are compressed near the middle portion of the vertical walls. consequently, at ra = 10 5 , the temperature gradients near both the bottom and side walls tend to be significant to develop the thermal boundary layer. due to greater circulation near the central core at the top half of the enclosure, there are small gradients in temperature at the central regime whereas a large stratification zone of temperature is observed at the vertical symmetry line due to stagnation of flow. the thermal boundary layer develops partially above the source for ra = 10 3 whereas for ra = 10 5 , the isotherms presented in (fig. 4c) indicate that the thermal boundary layer develops almost throughout the entire source. 7.2. effect of the source size streamlines and isotherms for e = 2/5, 3/5, and 4/5 at different rayleigh numbers are seen in figures 5, 6, and 7 respectively. the flow fields are nearly identical to those of (e =1/5) for each rayleigh number. however, the isotherms are effected by the increasing of (e) due to the heated part of the lower surface which is larger than that of (e =1/5), the heating effect in this case is much more sensible for the same values of rayleigh numbers. for fixed ra, with increasing (e), the flow field remains almost the same, while the temperature fields changes become more stratified for larger values of ra. 7.3. heat transfer rates: local and average nusselt numbers owing to the symmetry in the temperature field, heat transfer is symmetrical with respect to mid-length (x =l/2), this is illustred in figure (8) which shows the local nusselt number along the heat source for (e = 4/5) for different rayleigh numbers. the heat transfer rate (nu) is very high at the edges of the source due to the discontinuities present in the temperature boundary conditions at the edges and reduces towards the center of the bottom wall with the minimum value at the center due to the plume formation at the center of the source. plots of the average nusselt number on the heated source as a function of (ra) and (e) are shown in figure 9. for a fixed (e), increasing ra enhances convection. and increasing (e) for a fixed (ra) results in an increase at nusselt number. these results can be clearly explained under the views of isotherms given in figures 4, 5, 6, and 7 0.20 0.40 0.60 0.80 x 0.00 5.00 10.00 15.00 20.00 25.00 n u ra=1000 ra=10000 ra=100000 fig.8. local nusselt number on the bottom wall of the enclosure for ra =10 5 , pr=0.7 and for (e =4/5). 1000.00 10000.00 100000.00 ra 0.00 2.00 4.00 6.00 8.00 10.00 n ua e=4/5 e=3/5 e=2/5 e=1/5 figu.9. average nusselt number versus rayleigh number for three different values e. ahmed w.mustafa al-khwarizmi engineering journal, vol.8, no.1, pp 7685 (2012) 83 8. conclusions the finite volume method with collocated grid is used to analyze the natural convection in trapezoidal enclosure heated partially from below. the heat transfer rates have been analyzed with local and average nusselt numbers for the bottom wall of the enclosure. the results show 1the average nusselt number increases with increases of the source length. 2the local nusselt number is symmetrical with respect to midlength for different source lengths and different raleigh numbers nomenclature c1 contravariant velocity in δ direction c2 contravariant velocity in ε direction g gravitational acceleration, m/s 2 h dimensionless enclosure height j jcobian transformation k thermal conductivity, w/m k l enclosure width nu nusselt number = hl/k p pressure(pa) p dimensionless pressure pr prandtl number, cp µ/k ra rayleigh number e heat source length e dimensionless heat source length t temperature, k u,v velocity components in the x and y direction, m/s u,v dimensionless velocity components in and y directions x,y space coordinates in cartesian system x,y dimensionless cartesian coordinates s source term greek symbols β coefficient of volumetric thermal expansion, k. -1 α ,β,γ dimensionless coordinate transformation parameters г dimensionless diffusion coefficient ζ dimensionless temperature υ kinematic viscosity, m 2 /s ρ density kg /m 3 δ ,ε dimensionless curvilinear coordinates φ dimensionless dependent variable φ angle subscripts c cold surface h hot surface 9. references [1] iyican l., bayazitoglu y., an analytical study of natural convective heat transfer within trapezoidal enclosure, asme j. heat transfer102 (1980) 640–647. [2] peric´ m., natural convection in trapezoidal cavities, numer. heat transfer a 24 (1993) 213–219. [3] kuyper, r.a. hoogendoorn, c.j. “laminar natural convection flow in trapezoidal enclosures”, num. heat transfer, part a 28 (1995) 55–67. [4] natarajan e.., tanmay basak, and roy s., natural convection flows in a trapezoidal enclosure with uniform and non-uniform heating of the bottom wall, int. j. heat mass transfer, 51, 747–756, 2008. [5] basak t., roy s., and pop i., heat flow analysis for natural convection within trapezoidal enclosures based on heatline concept, int. j. heat mass transfer 52, 2471–2483, 2009 [6] bejan a., “heat transfer”, john wiley and sons, 1993. [7] thompson, j.f., warsi, z.u.a., and mastin, c.w., numerical grid generation, foundations and applications. elsevier, new york 1985. [8] rhie, c. m., and chow, w. l., numerical study of the turbulent flow past an airfoil with trailing edge separation, aiaa journal, 21, 1525-1532, 1983. [9] wang y. and komori s., on the improvement of the simple-like method for ahmed w.mustafa al-khwarizmi engineering journal, vol.8, no.1, pp 7685 (2012) 84 flows with complex geometry, heat and mass transfer 36, 71-78, 2000. [10] ferziger, j.h. and peric, m. computational methods for fluid dynamics, springer 1996. [11] aydin, o. and yang w., natural convection in enclosures with localized heating from below and symmetrical cooling from sides, int. j. of numerical methods for heat and fluid flow, vol. 10, no. 5, 518–529, 2000. (2012 )85 76، صفحة 1، العذد 8 المجلذ احمذ وحيذ مصطفى مجلة الخىارزمي الهنذسية 85 الحمل الحر في حيس شبة منحرف مسخه جسئيا مه االسفل ** أحسان علي غني* أحمذ وحيذ مصطفى جايؼت حكرَج/ كهُت انهُذست / قسى انهُذست انًُكاَُكُت* انجايؼت انًسخُصرَت / كهُت انهُذست/ قسى انهُذست انًُكاَُكُت ** ahmedweh@yahoo.com :انبرَذ االنكخروٍَ * iaghani68@yahoo.com : انبرَذ االنكخروٍَ** الخالصة انخسخٍُ حى حًثُهت بىاسطت يصذر حرارٌ . انحًم انحر فٍ حُس شبه يُحرف يغ حسخٍُ جسئٍ يٍ االسفم وحبرَذ يخُاظر يٍ انجىاَب حى دراسخه ػذدَا حقم انجرَاٌ انطباقٍ حى ححهُهت . حى اػخبرها فٍ انذراسه( 4/5 ,3/5 ,2/5 ,1/5) اربغ قُى يخخهفه يٍ طىل انًصذر هٍ ،يىضىع ػهً يركس انجذار انسفهٍ يركباث انسرع انذكارحُت وانضغظ ػهً شبكت يخحذة انًىقغ اسخخذيا كًخغُراث . ػذدَا بحم يؼادالث َافُر سخىك وانطاقت انثُائٍُ انبؼذ ونهحانت انًسخقرة حى حىنُذ شبكت انحم ،َظاو حطابق االحذاثُاث اسخخذو نخًثُم شكم انحُس بشكم دقُق. يخؼًذة فٍ يؼادنت انسخى انخٍ حى حقطُؼها باسخخذاو طرَقت انحجى انًحذد انُخائج بُُج اٌ . (ra ≤105 ≥103) يذي رقى راَهٍ هى . اسخخذيج نخحقُق حفع انكخهتsimpleخىازيُت . انؼذدٌ بحم يؼادالث حفاضهُت جسئُت بُضىَت . يخىسظ رقى َسهج َسداد بسَادة طىل انًصذر mailto:ahmedweh@yahoo.com������ mailto:ahmedweh@yahoo.com������ mailto:ahmedweh@yahoo.com������ mailto:ahmedweh@yahoo.com������ mailto:iaghani68@yahoo.com طه ياسين al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 7079 (2013) influence of the applied potential and temperature on the electrodeposition of the lead dioxide taha yaseen khalaf department of biomedical engineering / al-khawarizmi college of engineering / university of baghdad email: taha_y9@yahoo.com (received 21 may 2013; accepted 11 september 2013) abstract the excellent specifications of electrodes coated with lead dioxide material make it of great importance in the industry. so it was suggested this study, which includes electrodeposition of lead dioxide on graphite substrate, knowing that the electrodeposition of lead dioxide on graphite studied earlier in different ways. in this work the deposition process for lead dioxide conducted using electrolytic solution containing lead nitrate concentration 0.72 m with the addition of some other material to the solution, such as copper nitrate, nickel nitrate, sodium fluoride and cetyl trimethyl ammonium bromide, but only in very small concentrations. as for the operating conditions, the effect of change potential and temperature as well as the time on the deposition process was studied. the results shown at the end of the experiments that the change in the applied potential to the cell and electrolytic solution temperature had the greatest influence on the cell current, anodic current density, anodic overpotential and the amount of lead dioxide deposited on the anode. keywords: electrodeposition; lead dioxide; alpha-lead dioxide. 1. introduction electrodeposition, electroplating or electrochemical deposition is the process by which an applied current or potential is used to deposit a film of metal or alloy from by the reduction of metallic ions onto a conductive substrate [1 2]. in the case of electrochemical metal phase formation creating crystalline metal deposits, the process is known as electrocrystallization. more generally, the term electrodepositionis used [2]. electrodeposition is the application of a coating to conducting surfaces by electrochemical processes, and is usually confined to metallic coatings, although other materials such as metal-oxides are also possible [3]. the heterogeneous transfer of electrons from the solution environment is clearly a key process in electrodeposition [2]. the electrodeposition of particulates along with a metal or alloy leads to the formation of a composite [1]. the pulse electrodeposition is a modified form of electrodeposition in which either pulse current or pulse potential is applied to the electrode for a given duration of time. metal deposits obtained by pulse plating show distinct advantages like improved deposit distribution, minimized edge effect, pinhole free deposit, less hydrogen uptake, uniform thickness, better adhesion and lower impurity content compared to conventional dc electrodeposition. the characteristics of the films deposited by pulse electrodeposition are controlled by factors like on-time, off-time and current density [4]. 2. lead dioxide electrodeposition during the past decade, lead dioxide (pbo2) anodes sparked a worldwide interest and were used frequently in industry because of their excellent properties such as high electronic conductivity, high over oxygen evolution, high mailto:taha_y9@yahoo.com taha yaseen khalaf al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 7079 (2013) 71 stabilityin medium, good electrocatalytic activity and relatively high service life [5 6]. a great number of applications for lead dioxide such as positive active material in lead acid batteries, electrochemical sensors, electrowinning of metals,oxidation of organic compounds inwaste water, oxidation of glucose, ozoneevolution, oxidation of phenol and cr+3 has been reported [6 7].the substantial growth in new avenuessuch as telecommunication networks, electronics, computers etc., has raised new challenges for pbo2batteries[7].it is a cheap alternative material that can substitute noble materials such as platinum. its use inorganic electrosynthesis is also highly recognized [8]. electrodeposited pure leaddioxide was demonstrated to exhibit a moderate electrocatalyticactivity toward various anodic reactions inacidic media. however, this activity can often been hanced greatly by incorporation of some ions, for example bi+3, as+3, fe+3, cl-, f-. there is much lessinformation on effects of polyelectrolyte and surfactantadditives on the process of oxide electrodeposition and thephysicochemical properties of the resulting materials. it was shown that both polyelectrolytes and anionicsurfactants are adsorbed on pbo2 and that the compositematerials prepared from plating solutions containing thoseadditives have new physicochemical properties [9 10]. in practice, the materials with large o2overpotential are commonly chosen as the anode. metal oxides are probably the most interesting material for use in electrocatalysis. there are a number of oxides electrodes (ruo2, iro2, sno2 and pbo2) that may be used as anode materials for the oxidation of organic compounds [11]. there are two forms of pbo2; αpbo2(orthorhombic structure) and βpbo2(tetragonal structure). electrochemically αpbo2is readily prepared in weakly acidic or alkaline solution by the oxidation of pb(ii) whilst β-pbo2can be easily prepared by the electrooxidation of pb(ii) from acidic solutions [6 11]. β-pbo2 also has higher stability inacid solutions than α-pbo2. different electrocatalytic activities of α and β forms of pbo2were reported in many studies. it was concluded that porous structured pbo2 with a high degree of crystallinity is more active and has influenced the electrocatalytic properties of the material. the porous structure of β-pbo2provides a greater surface area for anodic applications; therefore, the increased in the active surface area will increase the formation of oh radicals and will favour the degradation of organic compounds. the advantage of using of such electrodes is their high surface area and high mass transfer coefficient and hence high rate of electrochemical conversion [11]. 3. mechanism and kinetic of electrodeposition the prerequisite for the creation of new composite lead dioxide-based materials with specified electrocatalytic properties is the development ofnotions concerning the basic regularities that governthe lead dioxide electrodeposition process. there is a considerable body of works devoted to studying the regularities that govern the lead dioxide electrodeposition reaction. despite this fact, at present thereis no universal kinetic scheme of the lead dioxide electrodeposition process, which would satisfactorily describe the entire collectionof experimental data [12]. according to recentdata, in nitric acid the rate of pbo2electrodeposition process canbe limited by an electron transfer or a diffusionstage and the reactionmechanism is described by the follow scheme [12-15], h2o → ohads + h+ + e …(1) pb+2 + oh ads →pb (oh) +2 …(2) pb (oh) +2 + h2o→ pbo2 + 3h+ + e …(3) the first stage is the formation of oxygencontaining species such as chemisorbed oh, followed by a chemical stage in which these particles interact with the lead species forminga soluble intermediatespecies, likely to contain pb(iii), which is then oxidized electrochemicallyforming pbo2[14]. the potential e of the mz+ /m electrode is a function of the activity of metal ions in the solution according to the nernst equation, = + ln (m ) …(4) or converting the natural logarithm into the decimal logarithm yields = + 2.303 log (m ) …(5) where eo, r, t, z, and f are the relative standard electrode potential of the mz+ /m electrode, gas constant, absolute temperature, number of electrons involved in reaction and faraday’s constant (96487 c), respectively[16 17]. taha yaseen khalaf al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 7079 (2013) 72 for any electrodeposition to take place, a current has to flow through an electrochemical cell. when a net current flows through an electrochemicalcell, the electrode potential deviates from its equilibrium value. the difference between the actual electrode potential ( ) and the equilibrium potential ( ) is called the overpotential(η). it can be expressed by[18, 19], = − …(6) for large negative values of overpotentials (η≥ 100 mv), the current density i (i =i/s, where s is the surface area of theelectrode) increases exponentially with the overpotential η according to the following equation [20], = ° …(7) and for large positive values of overpotential (anodic processes) according to the following equation, = ° ( ) …(8) where ° is the exchange current density ( ° = when = 0), the transfer coefficient, and = …(9) the general form of the current–potential characteristics which takes into accountboth forward and reverse processes, when expressed in terms of overpotentialassumes therefore the following form: = exp − − exp ( ) …(10) this is the so-called butler–volmer (b–v) equation. the first term describes thepartial current density of the cathodic process and the second that of the anodic one. [19]. the activation overpotential is dependent upon the number of ions present in solution. the relationship between activation overpotential and the current density can be shown by the tafel equation [20 -21], = ∓ log| | …(11) wherea and b are constants and |i| is the absolute value ofthe current density. the∓sign holds for anodic and cathodicprocesses, respectively. the theoretical value of the constanta for the anodic process, is = − . ( ) log … (12) and that of is = . ( ) …(13) the objective of the present study was to develop a practical pbo2 anode that could be used in industrial electrolyte processes. therefore, the graphite was selected as a substrate of lead oxide in the experiments due to it is cheap. in particular we evaluated the influence of temperature of solution and applied voltage on polarization of anode and cathode. faraday’s law indicates that the weight of the metal deposited in an electrolytic process is proportional to the current, plating time and its chemical equivalent.thus: = …(14) where w is the weight (in grams) of metal deposited, i is the current (a), t is time (sec) and e is the chemical equivalent. the product of current and time (it), is the quantity of electricity passed. for a given coulomb, the weight of an element discharged is proportional to its chemical equivalent. one faraday (f) depositsa gramequivalent of an element of atomic weight,a [22].thus: = …(15) 4. experimental work 4.1. assembly cell the cell consisted of a glass beaker pyrextype with a capacity of 250 ml covered with a piece of poly vinyl chloride material. two rectangular copper plates area each one 1.6 cm2 and a sheet of graphite [23] were used as the cathode and anode, respectively. 4.2. anode a graphite electrode (2 cm × 0.3 cm × 1.5 cm) served as anode. it was placed in the center between the two copper plates of the cathode. before electrode graphite was placed in solution electrolytic than should be a pretreatment, where surface graphite using sand paper and washing the sheet with water and liquid soap to remove fatty substances and impurities that may be present on the surface. later, it was immersed in distilled water for 1/2 to 1 hour at a temperature of 25 to 30 oc, so water-filled pores. upon removal from the immersing bath, the substrate is immediately transferred to the electrolyte. taha yaseen khalaf al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 7079 (2013) 73 4.3. solution electrolytic solution plating pbo2 could be prepared by dissolving lead nitrate in water to produce an aqueous solution with a concentration of 0.72m. aqueous solution had also some materials and certain concentrations, as follows: 10 g/l nickel nitrate, 14 g/l copper nitrate, 0.75 g/l cetyl trimethyl ammonium bromide and 0.75 g/l sodium flouried. 4.4. electrolysis operating conditions for the deposition process were identified by several factors as follows: first, the applied potential was changed from 2, 2.5, 3, 3.5to 4 volts, knowing that the time required for coating a single sample is 45 minutes. second, the temperature of the deposition solution was changed when the values 32, 46, 61 and 76co. in addition to the above, the value of the ph of the solution before starting the deposition must be adjusted to 3.5 ± 0.2 and the electrolytic solution must be mixed at a rate regularly using magnetic stirrer so as to remove any bubbles that may be present on the surface of graphite electrode. the objective of the present study was to develop a practical pbo2 anode that could be used in industrial electrolyte processes. therefore, the graphite was selected as a substrate of lead oxide in the experiments due to it is cheap. in particular we evaluated the influence of temperature of solution and applied voltage on polarization of anode and cathode. 5. results and discussion 5.1. effect of deposition time and temperature on the cell current figure 1 shows the relationship between the current with deposition time when deposition lead dioxide from an aqueous solution containing lead nitrate (0.72m), while the temperature change between 32 and 76oc. the change of the current appeared as a function of temperature when the rate mixing was fixed. the cell current increases with increasing temperature. in addition to that, there was no effect of deposition time on the cell current when the applied potentials were fixed or were very small. 0 10 20 30 40 50 60 70 deposition time (min) 0 1 2 3 4 5 6 7 8 c el l c ur re nt (a ) at v = 2 v & at t = 32, 46, 61 & 76 oc at v = 2.5 v & at t = 32, 46, 61 & 76 oc at v = 3 v & at t = 32, 46, 61 & 76 oc at v = 3.5 v & at t = 32, 46, 61 & 76 oc at v = 4 v & at t = 32, 46, 61 & 76 oc fig. 1. effect of depositiontime and temperature on the cell current. 5.2. effect of applide potential and temperature on the cell current results are displayed in figure 2 shows that the cell current proportional to the applied potential when the temperature difference. it is obvious that in all the experimentsthat the cell current increases with increasing applied potential. the logical explanation for that the increased applied potential leads to an increase in concentration of reactants around the electrodes and thus increases the amount of the deposit, which consequently leads to an increase in cell current. 1.8 2.0 2.2 2.4 2.6 2.8 3.0 3.2 3.4 3.6 3.8 4.0 4.2 applied potential (v) 1 2 3 4 5 6 7 c el l c ur re nt (a ) at t = 32 oc at t = 46 oc at t = 61 oc at t = 76 oc fig. 2. effect of applide potential and temperature on the cell current. in addition to the above, it can be seen two types of shapes, at a temperature of 32 and 61oc on the one hand and at temperatures of 46 and 76oc on the other. first at a temperature of 32 taha yaseen khalaf al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 7079 (2013) 74 and 61oc, it is noted that the cell current is increasing according to the law of the straight line. either in second form, the cell current increases are straight in the early stages. and then in the applied potential range 2.4 and 4, the cell current is increasing according to an exponential law, knowing that the values of applied potentials confined within this range are the most commonly used values in previous research [24]. 5.3. effect of applide potential and temperature on the anodic current density for the purpose of obtaining more information, we will study the current term anodic current density versus applied potential and this is what is shown in figure 3 where the anodic current density increases with the applied potential and temperature. the results showed the process of deposition of lead dioxide on graphite electrode that increasing the applied potential leads to increase the amount of material deposited on the electrode, as well as increase the anodic current density. 1.8 2.0 2.2 2.4 2.6 2.8 3.0 3.2 3.4 3.6 3.8 4.0 4.2 applied potential (v) -0.9 -0.8 -0.7 -0.6 -0.5 -0.4 -0.3 -0.2 -0.1 0.0 lo g an od ic c ur re nt d en si ty (a c m -2 ) at t = 32 oc at t = 46 oc at t = 61 oc at t = 76 oc fig. 3. effect of applide potential and temperature on current density. the increase of temperature of the electrolytic solution lead to change the physical properties of the solution, such as density and viscosity. in addition, the increase in temperature will lead to increase the kinetic energy of the ions and make it move more quickly and therefore it will be helpful to increase the speed of precipitation reactions, and this whole is the main reason for the increase in anodic current density. 5.4. effect of overpotential on the anodic current density to understand the behavior of the polarization curve of the anode, we calculated the overpotential of the cell using the basic equations mentioned earlier in paragraph mechanism and kinetics of electrodeposition, and then through the tafelequation of the anode, the data is plotted with the log current density of the anode versus overpotentialas shown in figures 4(a), (b), (c) and (d), while varying the temperature between 32 and 76oc. -0.8 -0.7 -0.6 -0.5 -0.4 -0.3 -0.2 -0.1 log anodic current density (a cm-2) 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 o ve rp ot en tia l ( v ) t = 32 oc fig. 4 (a). effect of overpotentialon the log anodic current densityat a temperature= 32 oc. -0.9 -0.8 -0.7 -0.6 -0.5 -0.4 -0.3 -0.2 -0.1 log anodic current density (a cm-2) 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 o ve rp ot en tia l ( v ) t = 46 oc fig. 4 (b). effect of overpotential on the log anodic current density at a temperature = 46 oc. taha yaseen khalaf al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 7079 (2013) 75 -0.7 -0.6 -0.5 -0.4 -0.3 -0.2 -0.1 log anodic current density (a cm-2) 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 o ve rp ot en tia l ( v ) at t = 61oc fig. 4 (c). effect of overpotentialon the log anodic current density at a temperature = 61 oc. -0.7 -0.6 -0.5 -0.4 -0.3 -0.2 -0.1 0.0 log anodic current density (a cm-2) 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 o ve rp ot en ti al (v ) t = 76 oc fig. 4 (d). effect of overpotential on the log anodic current density at a temperature = 76 oc. these figures show the variation of overpotential as a function of anodic current density at constant temperatures in each experiment. it was observed that the overpotential increases with increasing anodic current density. the plot of the overpotential versus log anodic current density isnon-linear. we note that the overpotential increases exponentially with the log anodic current density according to the equation 8,for large positive values of overpotential (anodic processes). 5.5. effect of temperature and applide potential on the overpotential fig. 5 shows the variation of overpotential versus temperature in the electrodeposition process for the various applied potential. we note from this figure that the overpotential not affected when increasing temperature, but the fact is that decrease very little in the overpotential at increasing temperature cannot distinguish clearly in figure the because of the narrow range of temperature and this is what can be detected clearly when you apply the nernst equation. as for the effect of applied potential on theover potential it is clear from the figure that the increase in the applied potential leads to an increase of the over potential. 30 35 40 45 50 55 60 65 70 75 80 temperature oc 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 o ve rp ot en tia l ( v) at v = 2 v, at v = 2.5 v, at v = 3 v, at v = 3.5 v, at v = 4 v fig. 5. effect of temperature and applide potential on the overpotential. 5.6. effect of temperature and applied potential on the log anodic current density figure 6 shows the effect of temperature on the log anodic current density at changing the values of the applied potential, as we have noted that the increase in temperature leads to an increase anodic current density and the reason for this is due to the increase in temperature reduces the viscosity of the solution, which leads to reduced resistance to movement of ions that make up the current. taha yaseen khalaf al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 7079 (2013) 76 30 35 40 45 50 55 60 65 70 75 80 temperature oc -0.9 -0.8 -0.7 -0.6 -0.5 -0.4 -0.3 -0.2 -0.1 0.0 lo g an od ic c ur re nt d en si ty m a c m -2 at v = 2 v at v = 2.5 v at v = 3 v at v = 3.5 v at v = 4 v fig. 6. effect of temperature and applide potential on the log anodic current density. 5.7. effect of applied potential and temperature on the deposition weight figure 7 shows the weight of deposited lead dioxide from an aqueous solution containing lead nitrate (0.72m) on graphite for varying applied potentials. it seems from this figure that the weight deposited increases with increase in the applied potential and also increases when the temperature increases. the experimental data in figure explain to us the amount of material deposited on the anode when the applied potential is changed making it easier for us to identify one of the most important operational conditions in the electrodepositing process and thus the possibility to control the amount of material deposited with the times. 1.8 2.0 2.2 2.4 2.6 2.8 3.0 3.2 3.4 3.6 3.8 4.0 4.2 applied potential (v) 2 4 6 8 10 12 14 16 18 20 22 24 26 28 d ep os iti on w ei gh t ( gr am ) at t = 32 oc at t = 46 oc at t = 61 oc at t = 76 oc fig. 7. effect of applide potential and temperature on the deposition weight. 5.8. effect of temperature and applied potential on the deposition weight the effect of temperature on deposition weight for the various applied potential is shown in figure 8. 30 35 40 45 50 55 60 65 70 75 80 temperature oc 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 d ep os iti on w ei gh t ( gr am ) at v = 2 v at v = 2.5 v at v = 3 v at v = 3.5 v at v = 4 v fig. 8. effect of temperature and applide potential on the deposition weight. the weight deposited increases with increasing temperature electrolytic solution, which means that the electrodeposition process can be improved by increasing the temperature. 6. conclusion this work demonstrates the influence of applied potential and temperature of solution on the performance of the lead dioxide deposition on a graphite electrode from lead nitrate solutions. the following conclusions were reached: 1. the increase in the deposition time had very little effect on the cell current, but in general, the increase in the time of deposition led to an increase in the weight of lead dioxide deposited. 2. the increase in applied potential during the deposition process lead dioxide had the greatest influence on the current and current density, which led to an increase in overpotential as well as the increase in the weight of deposited. 3. the results showed that the increase in the temperature of the electrolytic solution worked to improve the performance of the deposition process, as well as to increase the weight of the deposited. taha yaseen khalaf al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 7079 (2013) 77 7. references [1] amrit p., "electrodeposition of nickelcopper alloys and nickel-copper-alumina nanocomposites into deep recesses for mems", ph.d.thesis, university of louisiana state, may (2003). 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[21] chen b., guoz., huang h., yang x. and cao y., "effect of the current density on electrodepositing alpha-lead dioxide coating on aluminum substrate", acta taha yaseen khalaf al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 7079 (2013) 78 metall. sin. vol.22, no.5, october (2009) 373-382. [22] sadiku-agboolao., sadikue.r., ojoo.i., akanjio.l. and biotidarao.f., "influence of operation parameters on metal deposition in bright nickel-plating process", portugaliaeelectrochimica, acta29(2)(2011), 91-100. [23] pathym. s. v. and udupah. v. k., "oxygen overpotential of lead dioxide graphitesubstrate anode", elcctrochimicaacta. vol. 10 (1965) 11851189. [24] vasundaras., narsimhamk. c. and udupah. v. k., "effect of addition of lead acetateduring the deposition of lead dioxide from the nitrate bath", elcctrochimicaacta. vol. 16 (1971) 13011310. )2013( 7079، صفحة 3، العدد9مجلة الخوارزمي الھندسیة المجلد خلف طھ یاسین 79 الترسیب الكھربائي لثاني أوكسید الرصاص تأثیر الجھد المسلط ودرجة الحرارة على طھ یاسین خلف جامعة بغداد/ كلیة الھندسة الخوارزمي / قسم ھندسة الطب الحیاتي taha_y9@yahoo.com : االلكتروني البرید الخالصة لذلك اقترحت ھذه الدراسة، . بمادة ثاني أوكسید الرصاص جعل منھا ذات أھمیة كبیرة في الصناعة المواصفات الممتازة لألقطاب الكھربائیة المطلیة الترسیب الكھربائي لمادة ثاني أوكسید الرصاص الكرافیت، مع العلم أن عملیة والتي تتضمن الترسیب الكھربائي لمادة ثاني أكسید الرصاص على ركیزة من .بطرق مختلفة"سابقاعلى الكرافیت تمت درستھا حتوي على مادة نترات الرصاص بتركیز في ھذا العمل أجریت عملیة الترسیب لمادة ثاني أوكسید الرصاص باستخدام محلول الكترولیتي كھربائیي 0.72 m فلورید الصودیوم ومادة سیتایل مع إضافة بعض المواد األخرى إلى المحلول االلكترولیتي، مثل مادة نترات النحاس، ومادة نترات النیكل، ومادة بدراست تأثیر تغیر الجھد المسلط أما بالنسبة للظروف التفغیلیة، فقد قمنا". بان ھذه االضافات كانت بتراكیز قلیلة جدا" تراي ایثایل برومید األمونیوم، علما .ودرجة حرارة المحلول وكذلك الزمن على عملیة الترسیب الكھربائي على انتھاء التجارب بأن التغییر في الجھد المسلط على الخلیة االلكترولیتیة وكذلك التغییر لدرجة حرارة المحلول كان لھما التأثیر االكبربینت النتائج عند .على كمیة ثاني أكسید الرصاص المترسبة على األنود" تیار الخلیة، وكثافة التیار االنودي، وفوق الجھد االنودي وكذلك ایضا mailto:taha_y9@yahoo.com احمد فواد al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 8099 (2013) pressure control of electro-hydraulic servovalve and transmission line effect jafar mehdi hassan* yiqin xue** majid ahmed oleiwi*** ahmed fouad mahdi**** *department of mechanical engineering / university of technology **institute of mechanical engineering / cardiff school of engineering /uk *** department of control and system engineering / university of technology **** department of automated manufacturing engineering / al-khawarizmi college of engineering *emal: jafarmahdi1951@yahoo.com **emal: xue@cf.ac.uk ***emal: moleiwi@yahoo.com ****emal: afmkridi@hotmail.com (received 17 march 2013; accepted 31 october 2013) abstract the effected of the long transmission line (tl) between the actuator and the hydraulic control valve sometimes essentials. the study is concerned with modeling the tl which carries the oil from the electro-hydraulic servovalve to the actuator. the pressure value inside the tl has been controlled by the electro-hydraulic servovalve as a voltage supplied to the servovalve amplifier. the flow rate through the tl has been simulated by using the lumped π element electrical analogy method for laminar flow. the control voltage supplied to servovalve can be achieved by the direct using of the voltage function generator or indirect c++ program connected to the dap-view program built in the dapcard data acquisition connected to pc, to control the value of pressure in a selected point in the tl. it has been found that the relation between the voltage value and the output flow rate from the servovalve in most of the path is a linear relation. the matlab m-file program is used to create a representation state of the mathematical model to find a good simulation for the experimental open loop control test. keywords: electro-hydraulic servovalve, twin flapper nozzle, transmission line effect, open loop pressure control, voltage linearization equation, dap-view data acquisition. 1. introduction servovalves were developed to facilitate the adjustment of fluid flow based on changes in load motion. the twin nozzle flapper servo valve is a high quality parts combined from mechanical, electrical and hydraulic technology and has the advantages of large power ratio, fast response, and high level of control precision. it is widely used in industrial applications such as manufacturing systems, robotics, materials test machines, active suspension systems, flight simulation, injection moulding machines…etc. hydraulic systems are also common in aircraft, where their high powerto-weight ratio and precise control make them an ideal choice for actuation of flight surfaces [1]. although they are commonly placed as close as possible to the device to which they are supplying fluid in some applications, it is not possible to place servo valves close to the actuator due to the plant conditions. this is commonly seen in the steel rolling industry [2]. in the last decades, some researchers have published some works in the field of servo valves modeling. watton and hawkley, (1996) an approach is developed by utilizing measurements of transient pressure and flow rate at the inlet and outlet of the line. a time series analysis technique is used in mailto:jafarmahdi1951@yahoo.com mailto:xue@cf.ac.uk mailto:moleiwi@yahoo.com mailto:afmkridi@hotmail.com jafar mehdi hassan al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 80-99 (2013) 81 such a way that the number of unknown coefficients to be estimated is minimized. for three different line configurations and a range of operating conditions there is an accurate prediction which is shown for three different line configurations and a range of operating conditions. the evaluation of just two transmission line functions then allows a simple model structure to be used for the simulation of fluid power circuits incorporating long lines [3]. krus and nyman (2000) have demonstrated how the actuation system control surfaces with transmission line can be simulated using a flight dynamics model of the aircraft coupled to a model of the actuation system. in this way, the system can then be optimized for certain flight condition by "test flying” the system. the distributed modeling approach used makes it possible to simulate this system faster than real time on a 650 mhz pc. this means that even system optimization can be performed in reasonable time [4]. dong zhu and lu (2010) prove that the long pipeline in hydraulic system has some influence on system performances and causes the system to become unstable. they target a hydraulic servo system with long transmission line between hydraulic power supply and servovalve, a mathematical model considering pipeline effect established by means of the theories of transmission line dynamics and hydraulic control systems in which pipeline characteristics were depicted by lumped-parameter model. dong used amesim (a software for modeling, simulation and dynamic analysis of hydraulic and mechanical system based on bond graph and which is a production of imagine corporation of france) to simulate the impact on system dynamic behaviors which were investigated theoretically and the influences of pipeline structural parameters on hydraulic system dynamic characteristics were analyzed [5]. yang and moan (2011) studied a heaving-buoy wave energy converter equipped with hydraulic power take off. this wave energy converter system is divided into five subsystems: a heaving buoy, hydraulic pump, pipelines, non-return check valves and a hydraulic motor combined with an electric generator. a dynamic model was developed by considering the interactions between the subsystems in a state space form. the simulation results show that transmission line dynamics play a dominant role in the studied wave energy converter system. the length of the pipeline will not only affect the amplitude of the transient pressures but also affect the converted power transformed in the generator [6]. the purpose of this work is to study the control of pressure losses in the transmission lines of hydraulic system using a servovalve. a theoretical analyses and experimental test are used to perform the work by applying direct voltage to control the pressure in a specific point in tl. the system's dynamic characteristics have been tested by using a pc (personal computer) equipped with a data acquisition processor (dapcard). this will allow data based modeling to be carried out, allowing prediction of the system's response to a given control output. 2. system description 2.1.1. system hardware description as shown in fig. 1, the pressure supply line delivers hydraulic fluid from big power unit supply to the test rig at a pressure up to 150bar. a variable pressure relief valve is installed in the rig so the desired pressure can be achieved on the rig as the researcher needs. there is a temperature sensor and flow meter on the supply line to the servovalve. the valve to be used is an ultra servovalve from moog, of type 4658-249-810, shown in fig. 2; the valve consists of two-stage, nozzle/flapper, and dray torque motor unit. service port b (see fig. 1) is blocked rather than feeding to the annulus side of the actuator as might be expected. the service port a is the exit to the servovalve, where the second flow meter and pressure transducer located. the servo and actuator are connected via a long transmission line. this line is expected to have an important input to the dynamic response of the system due to its considerable length. the actual actuator is fixed into a position it cannot move. this is allowable because the system is used to provide adequate force to counteract roll bending under load (work roll bending system). the actual displacement of these actuators are small, and would ideally be zero. hence, when modeling this system it considered reasonable to ignore the small actuator movements. the pc records the data acquisition processor (dap card), which is connected to the transducer display and amplifier units as shown in fig. 1. jafar mehdi hassan al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 80-99 (2013) 82 fig. 1. schematic of system set up cardiff university laboratory. 2.1.2. system control software description the dap-card is connected to the pc and has its own operating system and it is provided with a program called dap-view through which the control of the dap-card is built. this program starts and stops collecting data, as well as outputting signals and logging every event. this project requires the use of custom written control commands, which will collect input signals to the card, process them in accordance with the desired control method, and pass them back to the dapview program to be sent to the equipment. custom commands are written in c+ + language and have to be compiled and downloaded into the dapcard. c++ programs can only be changed by the pc, so any adjustments to the custom commands require the removal of previous custom commands and recompilation and installation on the dap-card [7]. 2.2. servovalve construction the servovalve is an interface between low energy electrical signals and high-level hydraulic power. servo valves are electrically operated proportional directional control valves. they are usually four port units which control the quantity of fluid they pass, as well as the direction. most common servovalves are made in the form of a two-stage device [8]. 2.2.1. first stage the first stage contains a torque motor which operates an armature and this armature pivots a 'flapper' which is situated between two fixed nozzles. by applying a current to the torque motor, the armature is rotated, and this moves the flapper toward one nozzle, and away from the other. the flapper is located within the valve and hence is surrounded by hydraulic fluid. to keep jafar mehdi hassan al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 80-99 (2013) 83 the torque motor free from oil, the flapper is encased within a flexible 'flexure tube'[8]. 2.2.2. second stage second stage is typically a four-way spool valve that controls the fluid flow to two service ports. there is commonly a mechanical feedback system in the form of a feedback spring attached to the spool which acts to oppose the action of the torque motor on the flapper. see fig. 2[8]. fig. 2 . ultra /moog servovalve, type 4658 and its cross sectional view[9]. 2.3. servovalve modeling 2.3.1 steady state modeling of servovalve when an electrical current is applied to the coils of the torque motor, a torque is generated on the armature. the armature and flapper are supported on the flexure tube or sleeve which separates the electro-magnetic and hydraulic parts of the valve which also provides a low friction pivot see fig. 3. four force components are considered in the torque motor. these are a positive function of the applied current and the rotation. these are a positive function of the applied current and the rotation. these forces are opposed by a torque from the stiffness of the flexure tube, and the net hydraulic force acting on the flapper element [9]. = ∆ + − −( − ) …(1) the mechanical feedback element is one of the types of servovalve being considered. the torque of this feedback spring can be considered as follows for small values of θ: ( + ), = + ( + ) & = …(2) atonement equation (2) in (1) gives the total torque on the torque motor fig. 3, flapper and spring combination, noting that the torque is zero at steady state; the angle θ can be deduced [9]: = − ( − )− ( + ) − + ( + ) …(3) as can be seen from fig. 4, there is a hydraulic 'bridge circuit' which is supplied with system pressure. a small amount of fluid can flow out through the fixed orifice and onward to the two variable orifices created by the nozzle/flapper interface, ultimately returning to the tank. flapper/nozzles in conjunction with a pair of orifices used to generate a pressure difference by small movements of the flapper positioned midway between the nozzles, as shown in fig. 4 [10]. the spool area and velocity are a, u respectively. typically the nozzle diameter is dn= 0.5mm, the flapper clearance in the mid-position xnm= 0.03mm, and the orifice diameter do = 0.2mm. it is common for such a device to be used in servovalves as a mechanical feedback, the pressure difference generated being used to move the spool. it will be immediately clear from fig. 4 jafar mehdi hassan al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 80-99 (2013) 84 that at the flapper mid position, often called the null position, the maximum leakage flow back to tank will exist, hence producing a small inherent power loss. as illustrating example, the flapper is moved to the left, by electromagnetic means then pressure p1 will increase and pressure p2 will decrease, thus providing a pressure difference across the spool which will then move unless restrained in some way. the flow loss and power loss will decrease as the flapper position is changed [10]. to analyze the flapper-nozzle bridge, the conventional restrictor flow equations are appropriate and given by: = + , = ( − ), …(4) = − , = ( + ); …(5) = 2( − ) , = ( ) ; …(6) = 2 , = ; …(7) at condition in which the spool motion is negligible, the steady-state performance of the double flapper-nozzle amplifier may be derived from equating qa = qx and qb = qy. this gives: = ( ̅) = , = ( ̅) = , ̅ = ; …(8) = 16( ) ( ) ( ) , …(9) then the differential pressure is given by: − = 4 ̅[1 + (1 + ̅) ][1 + (1 − ̅) ], …(10) considering the null condition where ̅ = 0 and − = 0; that leads to: = = ( ) …(11) and the null gain condition is: ( ) ̅ = 4 (1+ )2 …(12) because flapper operation is designed to be around the central (null) position, the pressure difference generated may be simply written as: ( − ) = …(13) spool displacement is then determined from the force balance across the spool which is dominated by the feedback wire force and the spool flow reaction force: (p − p )a = ky + 2c a cosθ[p − p ],and a = wx …(14) and: p = p − p & p = p + p where, as will the spool end cross section area, the spool orifice area ao for rectangular ports have an area gradient w. by combining these equations then give the relationship between spool displacement and input current is as follows: if: α = ( ) ; …(15) = − + ( + ) + …(16) = 2 ( − ) …(17) then: = ( ) ( )( ) …(18) the spool displacement will be proportional to input current provided that the denominator of eq. (18) is positive. the flow reaction equivalent stiffness kfr will probably be much smaller than the wire stiffness k, so that the effect of load pressure difference pload may not present a problem. in practice, α << 1 and can be neglected. notice also that the destabilizing magnetic constant -km, the magnitude of which can be varied during manufacture, the process known as detuning. in particular, can be detuned to a very small value by magnetically increasing km and eq. (18) then becomes: ≈ ( ) …(19) the input electrical torque is balanced by the wire feedback torque because of spool position, and the flapper will return to its central position between the nozzles [10]. clearly, for the same servovalve, the value of k, r and b constants the spool displacement which can be proportional to current is dominated. jafar mehdi hassan al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 80-99 (2013) 85 fig. 3. feedback spring free body diagram [9]. fig. 4. schematic of a double flapper-nozzle amplifier used to move a spool [10]. 2.3.2 dynamic modeling of servovalve the steady state performance of the valve will need to be augmented by a model for the transient response, and also for the transient response of the fluid transmission line. this will allow predictive control to be used. for the servovalve that again requires a finite time to change its spool position in response to a change in applied current. the combination of these issues means that the design of both open-loop and closed-loop control systems should take into account these dynamic issues. for the force-feedback type shown in fig. 5, it is clear what components which contribute toward the overall dynamic performance. the use of a current-feedback servo-amplifier means that the current-buildup characteristic is extremely fast when compared with other elements of the servovalve. the dynamic effect caused by the time required to generate the drive current can be ignored. however, there are effects produced from the flapper inertia and fluid viscosity [10]. the current-buildup and the dynamic torque equations will have the following types: = ( − ) + ( − ) + [ + ( + ) ]( + ) + + …(20) apply the continuity equation on each side gives: ( ) − = + + …(21) ( ) − = − + …(22) where: = ( − ), = ( + ) & = va and vb are the internal, small volumes on either side of and within the flow resistance bridge. the static force balance at the spool, including the flow reaction force, is now modified to include the dynamic flow reaction force, the spool viscous damping, and acceleration effects: ( − ) = [ + ( + ) ] + 2 cos [ − ] + − + + …(23) where: = ( ) , = …(24a) obviously, the defining equations of servovalve are nonlinear, and the solution also requires the load specification so that the load pressure difference (p1 p2) can be derived. considering the equations presented, it will be seen that a valve dynamic performance depends not only on electrical-electromagnetic-geometry parameters but also on the load it supplied pload and, hence, on the load flow rate, the supply pressure ps , and the magnitude of the input current. jafar mehdi hassan al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 80-99 (2013) 86 the tank (return line) pressure is usually neglected in comparison to the line pressures. the port opening area (wxs) is proportional to spool displacement which is also proportional to the current applied to the electromagnetic first stage. servovalve manufacturers also quote the rated flow at the valve rated current and with a valve pressure drop of 70bar, that is, the total pressure drop across both ports. consequently the servovalve equations could be rewritten in the following form [10]. = ( − ) & = …(24b) from the previous equations and the contribution of dynamics behavior shown in fig. 5, the amount of hydraulic fluid flow from the servovalve depends on the pressure and the current value coming to servovalve amplifier. in the steady state condition, both of the electromagnetic and mechanical properties are considered constant, as well as the effect of the amplifier, which converted the voltage value coming from the dap-view programs to the servovalve amplifier. in other words, it can be considered that the hydraulic flow rate (q) is a function of the voltage and the pressure as follows: = ( , ) …(25) at steady state operating condition ( vss, p1ss, p2ss, q1ss, q2ss), the first linear term of the taylor series expansion for a nonlinear function will be employed. consequently small changes in each parameter lead to: = − & = + …(25a) = = − = …(25b) = = = …(25c) = = 2 − = 2( − ) …(25d) = = 2 = 2( ) …(25e) = = − = = 2( − ) = 2 , …(25f) also the servovalve equation could be written as: = ( − ) & = …(25g) in this application, the singe action operation will be considered, so the port b (number 2 in previous equations) has been canceled, see fig .1, thus, it is needed to consider the segment of the first port to find the value of flow gain and pressure coefficient equations (25b & 25d) at steady state condition. practically, the dynamic characteristic is often specified by the manufacturer as a frequencyresponse diagram for the spool position (input) and the flow rate (output) for a typical performance range. jafar mehdi hassan al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 80-99 (2013) 87 fig. 5. contribution to servovalve dynamic behavior [1] [10]. fig. 6. the line dynamics approximation using lumped π elements for laminar mean flow [4]. 2.4. transmission line modeling hydraulic pipelines, when they are of significant length, they have an important effect upon the performance of many systems. the electrical analogy is a useful mechanism for understanding this approach [10]. consider linear characteristics and a slug of fluid, (a) is cross sectional area and the length is (l ). a. fluid resistance: the pressure drop δp, along the fluid element for laminar flow , is given by: ∆ = → ∆ = …(26a) hydraulic resistance electrical resistance b. fluid compressibility: ∆ = → ∆ = …(26b) fluid compressibility electrical capacitance c. fluid inertia: the pressure drop that is due to fluid acceleration is given by: ∆ = , ∆ = → ∆ = …(26c) fluid mechanical mass electrical inductance → = , → = & → = ...(26d) if a system is expected to have a frequency component that is comparable with this frequency, line dynamics must be modeled with some accuracy. the issue is how to distribute r, l and c in the line and how many "lumps" should be used [10]. this work shows a two-lump approximation using a pair of π networks as shown in fig. 6. the set of equations using this approximation, and working from left to right, may then be written as follows: − = , − = , − = …(27a) − = + , − = + …(26b) these equations can be resolved when the input and the output pressure flow relationships jafar mehdi hassan al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 80-99 (2013) 88 have been included to close the solution. so the pressure and flow meter sensors are needed in the test rig to record the overall pressure difference between the input and output for the transmission line, as shown in fig. 1 and fig. 7. this pressure difference can be used to calculate the losses that occur in the tl and the fittings which include such as bends, elbows, restricted valves and sudden expansion or contraction and other minor losses. to solve the previous equations, it is necessary to make some practical experiences to achieve steady state condition, through collecting this kind of data. the values of unknown's constants mentioned in equations (25-25g) such as that flow and pressure gains can be calculated, as well as the losses that occur in transmission line. (a) top view for tl test rig. (b) side view for tl test rig & measurement unite. fig. 7. test rig transmission line, fluid power laboratory, w20/ school of engineering / cardiff university/ uk. fig.8 voltage function generato jafar mehdi hassan al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 80-99 (2013) 89 3. experimental approach 3.1. modeling assumptions fluid properties: as an initial condition, fluid properties will be; density of the hydraulic oil 860kg/m3, absolute viscosity will be taken as 0.0258kg/m*s. effective bulk modulus will be 1.5gn/m2. temperature effects are considered to be negligible, because the hydraulic system is supplied with a heat exchanger which maintains the hydraulic fluid temperature does not exceed 50oc. pressure variation effects are expected to be negligible, but will be investigated with respect to bulk modulus to confirm the system time-delay, a function of bulk modulus which is not affected. the bulk modulus is expected to be independent of pressure variation if there is considerable air in the system (either dissolved or as bubbles) so in this case there may be an effect. transmission line dimensions: tl consist of one 16m length of steel pipe the internal diameter is 12.5mm, wall thickness 2.3mm and with young's modulus of 210gn/m2 see fig.7 (a). pressure transducer: (parkersensor, type: scp-150-1-06, 0-20 ma), shown in fig.7 (b). the sensor response will be considered to be ideal, i.e. pure gain with no time delay. as investigated from (hawkley), the transducer response has been considered an ideal sensor [11]. flow meter: (parkerflowsensor, type; scq-150-0-02, range -150_+150 l/min, -3_+3 vdc), as illustrated in fig. 7(b). the response will be considered accepted after subtracting the offset values at zero system pressure. the system has a continuous nature the sample time must be kept to a minimum to avoid loss of dynamic characteristics. the dap view cannot take more than 1gbytes and the maximum voltage with applied to the servovalve is 10volt. transmission line termination is assumed to be a simple (capacitor, resistance and inductance); the actuator cannot move (constant volume) as well the zero internal leakage is expected. calibration of pressure transducer and dap-card, in all figures presented in this work, it presents a y-axis value of 'digital output' supplied from the pressure transducer to the dap-card and saved in excel-file. these values should be translated from digital voltage value to pressure value in bar. the digital sensor values are multiplied by (9.1*10-3). calibration of flow-meter and dap-card, to calibrate the flow rate in (l/min), the digital output from flow meters which collected by the dap-card is needed to multiply by 15.26*10-3. 3.2. open loop pressure control results relying on the reference signal generator (function generator) fig. 8, the generated voltages are sent to the servovalve to change the system pressure in the chosen control point, and by using two types of waveforms, sinusoidal and square-wave. the voltages value was used in function generator ±4volt. the delivery pressure line is set to be 50bar, noting that the highest values can dap-card that gives it to the servovalve is 10volt. the results are as shown in figures (fig. 9, fig.10 & fig. 11). in these figures, the frequency values have been seized by using the voltages function generator as1hz. 3.3. servovalve transient response to find servovalve response and the amount of flow rate resulting from change voltage value, it is necessary to set up a special program using c+ + language in the pc and use the dap-card ports to send the voltage signal to the servovalve amplifier card. this voltage signal energizes the servovalve torque motor to move the spool of the valve to build the pressure in transmission line. the c+ + program needs to change the voltage value gradually step by step at time interval of 2seconds to get a dynamic stability. this program starts from zero value to the highest value given by dap-card (10volt) and then back to a zero value. the stability can be observed in the flow rate in each step of the program as shown in fig.12. after obtaining the flow values at each step, calculate the average flow rates in each step inside transmission line to find the relationship between voltage change and flow rate values changing. the flow rate measuring at point 2 (see fig.1), represents the servovalve transient response output by the effect of the voltage input as illustrated in fig.13. 3.4. the transmission line losses and the servovalve gains to find the properties of flow inside the transmission line, a steady state conditions has been create to record the values of pressure and flow rate inside the tl. by using these data, the servovalve gain could be found from the excelfile that has been recorded by employing the jafar mehdi hassan al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 80-99 (2013) 90 equations (25b, 25d & 25f). at 1.5 degree opening restrictor valve, the pressure inside the tl is accumulated. 50bar as a pressure line system is supply with a direct control using the voltages function generator. the results are coming from the square-wave voltage illustrated in fig. 14 & fig. 15. through the act of the experimental test, the nature of the flow rate has been checked as a laminar flow by calculating the reynolds number and the velocity from recorded flow. the relation between the voltage and the spool position inside the servovalve has been found from bode diagram supported by manufacturer data sheet, see {appendix-a}. the fluid power unit of the laboratory supplies many test rigs. so it was difficult to find out the miner losses through the line supply the test bench which have been used as well as the fluctuation effect. the minor losses mean the pressure drop due to elbows, junction, reducers, valves and hoses…etc. the major losses occurring in tl can be calculated from the equation below [12]: ∆ = 4 ( ∗ ) , ℎ : = …(28a) an experimental test have been used to find the total losses ( δptotal) between point 2 & 3 as located in fig. 1, where: ∆ = ∆ + ∆ …(28b) then: ∆ = 4 ( ∗ ) …(28c) so the equivalent length lequiv = 18.46m, and the corrected total tl length become: = + …(28d) the total corrected length (lc=l) has been used in equations (26d) to solve the mathematical model. 3.5. matlab simulation and results to find a mathematical model for the tl equations (27a and 27b) and the servovalve flow rate equations (24) supported by the voltage linearization equations (25b, 25d & 25f) that mentioned before, matlab m-file program can be used to represent the transmission line effect after converting to electric analogy. there has been a great complexity of the hydraulics system in the fluid power laboratories in cardiff university and the large size of the power unit system as well as the length of the pipes connected with tl test rig. besides, the hydraulic pressure provided for two laboratories and several hydraulic apparatus are connected to them. for this reasons, some assumptions have been taken in to account such as: the pressure provided by the supplied pressure line which delivers the fluid to the servovalve was considered as constant pressure in matlab program. this will neglect the fluctuation of the pressure value caused by system complexity. to find a clear comparison between the selected practical experiences and the program built by using matlab m-file, it is essential to find the values for the gain needed. the sample was taken from the recorded data, which represent a step input supplied by the function generator and compared to the output values resulting from the matlab m-file designed program. as shown in figures (fig. 16a & fig. 16b) and (fig. 16c & fig. 16d), the consequence output values are compatible in the behavior as well as the value. the exceptions of that compatibility seen in the overshot behavior can be explained by the pressure input values in the instant of the step input. the pressure input value to the servovalve is decreased in the instant of the step input while the pressure input value in matlab program maintains in constant value. the result predicted from matlab m-file program shows the pressure values variation in the effect of servovalve opining and the tl delay effect as illustrated in fig.16b. the noise and oscillations shown in fig 15 and fig.16c, for the values of flow rate result from the nature of flow meter design. as mentioned previously there is an error should be dealt with and reduced by subtracting the offset value and depending on the average values to solve the mathematical equations. the matlab m-file program can create a various shape of input voltage value (sine-wave or square-wave). the pressure and flow rate output could be seen for square wave in fig. 17a & fig17b. the behaviors of the mathematical model have a good approach comparing to the experimental test seen in fig. 14 & fig.15. the sine-wave input voltages generated in m-file program are supplied to the servovalve, the pressure and flow rate output shown in fig.18a & fig. 18b. it is clear that there is a delay effect of the tl especially in pressure output as seen in fig. 18a. jafar mehdi hassan al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 80-99 (2013) 91 fig. 9. open loop controlled by voltage function generator ps=52bar with sin-wave voltage amplitude fg=4volt. fig. 10. open loop controlled by voltage function generator ps=50bar with square-wave voltage amplitude fg=4volt. fig. 11. open loop controlled by voltage function generator ps=50bar with saw-wave voltage amplitude fg=4volt. jafar mehdi hassan al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 80-99 (2013) 92 fig. 12. flow rate and servovalve voltage data variation in transmission line at ps=70 bar. fig. 13. transient responses of servovalve. fig. 14. open loop controlled by c++ program (1.5 degree opening from the restrictor valve), square-wave, p1=50bar, fr=0.25hz. jafar mehdi hassan al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 80-99 (2013) 93 fig. 15. open loop controlled by c++ program (1.5 degree opening from the restrictor valve), square-wave, p1=50bar, fr=0.25hz. fig. 16a. open loop controlled by voltage function generator p1=50bar, time sampling = 8ms. fig. 16b. open loop controlled by matlab m-file p1=50bar, time sampling = 1ms. jafar mehdi hassan al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 80-99 (2013) 94 fig. 16c. the flow rate in open loop controlled by voltage function generator p1=50bar, time= 2.5 s. fig. 16d. the flow rate in open loop controlled by matlab m-file p1=50bar, time= 2.5 s. fig. 17a. the pressure values in open loop servovalve controlled, by matlab m-file p1=50bar, square wave, time= 4.0s. jafar mehdi hassan al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 80-99 (2013) 95 fig. 17b. the flow rate values in open loop servovalve controlled, by matlab m-file p1=50bar, square wave, time= 4.0s fig. 18a. the pressure values in open loop servovalve controlled, by matlab m-file p1=50bar, sine wave, time= 4.0s. fig. 18b. the flow rate values in open loop servovalve controlled, by matlab m-file p1=50bar, sine wave, time= 4.0s. jafar mehdi hassan al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 80-99 (2013) 96 4. conclusions foregoing became clear that the use of the open loop control study is very important to know the properties of the system and its capabilities. the open loop concept is the first step to entrance and design the efficient closed loop control to attenuate the delay tl effect. the servovalve (mechanical feedback) is one of the efficient valves that can be used to control the specific pressure value on the actuator. to reduce the impact of losses resulting from the hydraulic flow rate inside a long tl, the closed loop concept should be used. the lumped π element electrical analogy method for laminar flow is an efficient method which simulates the tl module. the relation between the flow rate and the supplied voltage of the servovalve amplifier is almost a linear relation one and the effect of design complexity could be neglected. this concept is so clear in the transient response of the electro-hydraulic servovalve. found through experimental tests that the value of the time sampling recorded through a dap-view program could be taken as 1 millisecond and that provided a good accurate data that can be used to calculate the simulation system in matlab m-file program. the dapview program is used to control the servovalve and it shows a precise action and follows the program designed in c+ + formula with different shape of functions. nomenclature latin characters character description units a hydraulic pipeline cross section area m2 an, anx, any nozzle cross section area m2 an the nozzle area m2 as the spool cross section area m2 ao the spool orifice area m2 bv the fluid viscous coefficient m2 cq, cqn, cqo the flow coefficients of the orifices and the nozzles c electrical capacitance farad di pipe ( transmission line) internal diameter m dn the nozzle diameter m do the orifice diameter m ei electrical inductance f frequency hz fg voltage input from the voltage function generator volt f darcy friction factor q1, q2 flow rate from servovalve m3/s, l/min qa, qb the orifice discharge m3/s qx, qy the nozzle discharge m3/s i the input torque motor current ma i current a δi input differential current ma j the flapper inertia kgm/s pa, pb pressure at nozzle a and nozzle b n/m2 pload the pressure difference on the load n/m2 ps system pressure n/m2; bar ka flexure tube rotational stiffness nm/ra d kc servovalve constant kf the cantilever springs stiffness nm/ra d kfr the flow reaction equivalent stiffness km electromagnetic spring constant of torque motor nm/ra d kt electromagnetic constant of torque motor nm/a mp l hydraulic pipeline length m l electrical inductance henry lc corrected length m lequiv equivalent losses length m ltl transmission line length m r electrical resistance ω r the distance between the nozzle center line and flexure joint m the torque on the flexure tube n.m tf the resisting torque n.m u the spool velocity m/s u3 the output mean flow rate velocity from the servovalve m/s u control signal volt v volume m3 ve electrical voltage volt v input voltage volt w the rectangular port area gradient m jafar mehdi hassan al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 80-99 (2013) 97 x the displacement of the flapper at the nozzles m xs the spool displacement m xnm flapper clearance in the mid position y total spring deflection m z constant for the servovalve design parameter (valve characteristic) greek symbols character description units β effective bulk modulus n/m2 µ fluid absolute viscosity kg/m.s ρ fluid density kg/m3 θ the rotation of the armature and flapper rad subscripts ss steady state operation condition 5. references [1] dsp control of electro-hydraulic servo actuators (january 2005), application report, texas instruments spraa76. [2] le bon. a. & hug, p. (1996), "book of steel, "the manufacture of plain carbon sheet steels reheating and hot rolling", lavoisier publishing. [3] watton, j., & hawkley, c. j. (1996). an approach for the synthesis of oil hydraulic transmission line dynamics utilizing in situ measurements. proceedings of the institution of mechanical engineers, journal of systems and control engineering, part i, 77-93. [4] krus, p. &. (2000). complete aircraft system simulation for aircraft design paradigms for modelling of complex system. icas 2000 congress (pp. 613.1-613.9). sweden: department of mechanical engineering, linköping university. [5] dong, c., zhu, y., & lu, j. (2010). modeling and dynamic behavior analysis of a hydraulic servo system with consideration of pipeline effect. international conference of logistics engineering and management: logistics for sustained economic development infrastructure, information, integration (pp. 3153-3160). harbin, china: college of engineering and technology, northeast forestry university. [6] yang, l. & moan, t. (2011). dynamic analysis of wave energy converter by incorporating the effect of hydraulic transmission lines. ocean engineering, elsevier, vol. 38, pp. 1849-1860. [7] dap-view user manual, microstar labs, 2001. [8] cundiff, j. s. (2002). fluid power circuits and controls: fundamentals and applications. library of congress cataloging-inpublication: (mechanical engineering series), tj840.c85 2001, 621.2—dc21. [9] watton, j. (1989). fluid power systems, modeling, simulation, analog and microcomputer control. uk: prentice hall. [10] watton, j. (2009). fundamentals of fluid power conntrol. cambridge/uk: cambridge university press. [11] hawkley, c. j. (1996). the modelling and simulation of an electrohydraulic pressure control system.phd, thesis. uk: school of engineering, uwcc, cardiff university. [12] frank m. white (2005), fluid mechanics fourth edition, university of rhode island mcgraw-hill series in mechanical engineering. jafar mehdi hassan al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 80-99 (2013) 98 )2013(8099 ، صفحة 3، العدد9مجلة الخوارزمي الھندسیة المجلد جعفر مھدي حسان 99 السیطرة على الضغط باستخدام الصمام الموازر الكھروھیدرولیكي وتاثیر الخط الناقل للھیدرولیك ***ماجد احمد علیوي **یكن اكسو * جعفر مھدي حسان ****احمد فؤاد مھدي الجامعة التكنولوجیة/ قسم الھندسة المیكانیكیة * بریطانیا -جامعة كاردف/ كلیة الھندسة ** الجامعة التكنولوجیة/ قسم ھندسة السیطرة والنظم *** كلیة الھندسة الخوارزمي/ قسم ھندسة التصنیع المؤتمت **** jafarmahdi1951@yahoo.com : البرید االلكتروني* xue@cf.ac.uk : البرید االلكتروني** moleiwi@yahoo.com :البرید االلكتروني*** afmkridi@hotmail.com :البرید االلكتروني**** الخالصة ھذه الدراسة تركز على نمذجة الخط الناقل . و صمام السیطرة مھم ومؤئر) المحرك(في بعض الحاالت یعتبر الخط الناقل للھیدرولیك بین المستھلك تمت السیطرة على قیمة الضغط داخل الخط الناقل من خالل السیطرة على . بین صمام السیطرة الموازر الكھروھیدرولیكي والمستھلكللھیدرولیك الواصل ى للكم لتحویل الخط الناقل ال πتمت نمذجة الجریان الطباقي داخل الخط الناقل باستخدام طریقة . قیمة الفولتیة الواصلة الى المضخم الخاص بصمام الموازر ) ++c(تم استخدام الطریقة المباشرة في التحكم بالفولتیة من خالل جھاز مولد دالة الفولتیة وبشكل غیر مباشر من خالل استخدام برامج ال . منظومة كھربائیة رات الشخصیة للسیطرة على التي یمكن أضافتھا الى الكومبیوت) dap-card(المنصب اصال في الدائرة الكھربائیة ) dap-view(والذي یرتبط مع برنامج تم التوصل الى ان العالقة بین الفولتیة والجریان الخارج من صمام الموازر في اغلب االحیان عالقة . قیمة الضغط داخل الخط الناقل عند نقطة معینة مختارة جیدة لحالة السیطرة على الدائرة المفتوحة ومتماثل مع الیجاد حالة تمثیل ریاضي و وجد بأن النتائج كانت ) m-file(تم استخدام برنامج الماتالب . خطیة . التجارب العملیة mailto:jafarmahdi1951@yahoo.com mailto:xue@cf.ac.uk mailto:moleiwi@yahoo.com mailto:afmkridi@hotmail.com thermal buckling of rectangular plates with different temperature distribution using strain energy method al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 8, no. 2, pp 1 -11 (2012) restrained edges effect on the dynamics of thermoelastic plates under different end conditions wael r. abdul-majeed* muhsin j. jweeg** adnan n. jameel*** department of mechatronics engineering/al-khawarizmi college of engineering/ university of baghdad * ** college of engineering/university of al-nahrain *** department of mechanical engineering/college of engineering/university of baghdad (received 22 march 2011; accepted 9 january 2012) abstract frequency equations for rectangular plate model with and without the thermoelastic effect for the cases are: all edges are simply supported, all edges are clamped and two opposite edges are clamped others are simply supported. these were obtained through direct method for simply supported ends using hamilton’s principle with minimizing ritz method to total energy (strain and kinetic) for the rest of the boundary conditions. the effect of restraining edges on the frequency and mode shape has been considered. distributions temperatures have been considered as a uniform temperature the effect of developed thermal stresses due to restrictions of ends conditions on vibration characteristics of a plate with different will be investigated. it is noticed that the thermal stress will increase with increasing the heatnig temperature and that will cause the natural frequency to be decreased for all types of end conditions and for all modes of frequency. keywords: thermoelasticity, thin plate, ends condition, mode shape, natural frequency. 1. introduction thermoelasticity is concerned with questions of equilibrium of bodies treated as thermodynamic systems whose interaction with the environment is confined to mechanical work, external forces, and heat exchange. because of constraints, a non -uniform temperature distribution in a component having a complex shape usually gives rise to thermal stresses. it is essential to know the magnitude and effect of these thermal stresses when carrying out on rigorous design of such components. the thermal stresses alone and in combination with the mechanical stresses produced by the external forces will be effect on dynamics properties of apart such as natural frequency and mode shape . naji, et al. [1] studied the thermal stresses generated within a rapidly heated thin metal plate when a parabolic two-step heat conduction equation is used. the effect of different design parameters on the thermal and stress behavior of the plate is investigated. al-huniti, et al. [2] investigated the thermally induced vibration in a thin plate under a thermal excitation .the excitation is in the form of a suddenly applied laser pulse (thermal shock). the resulting transient variations of temperature are predicted using the wave heat conduction model (hyperbolic model), which accounts for the phase lag between the heat flux and the temperature gradient. the resulting heat conduction equation is solved semi analytically using the laplace transformation and the riemann sum approximation to calculate the temperature distribution within the plate. the equation of motion of the plate is solved numerically using the finite difference technique to calculate the transient variations in deflections. norris and photiadis [3] enabled direct calculation of thermoelastic damping in vibrating elastic solids. the mechanism for energy loss is thermal diffusion caused by inhomogeneous deformation, flexure in thin plates. the general result is combined with the kirchhoff assumption to obtain a new equation for the flexural vibration of thin wael r. abdul-majeed al-khwarizmi engineering journal, vol. 8, no.2, pp 1-11 (2012) 2 plates incorporating thermoelastic loss as a damping term. the thermal relaxation loss is inhomogeneous and depends upon the local state of vibrating flexure, specifically, the principal curvatures at a given point on the plate. the influence of modal curvature on the thermoelastic damping is described through a modal participation factor. the effect of transverse thermal diffusion on plane wave propagation is also examined. it is shown that transverse diffusion effects are always small provided the plate thickness. tran a, et al. [4] studied the thermally induced vibration and its control for thin isotropic and laminated composite plates. the structural intensity (si) pattern of the plates which have different material orientations and boundary conditions was analyzed. the thermoelasticity simulation is performed using the finite element method. it shows that the structural energy flows are dependent on the material structures as well as the boundary conditions for a prescribed thermal source. the position to attach a damper for controlling the thermally induced vibration is investigated based on the virtual sources and sinks of the si patterns. 2. analytical study the plate analyzed has usually been assumed to be composed of a single homogeneous and isotropic material with shape and dimensions as in fig. (1) [5]. fig. 1.schematic diagram of thin plate. 3. boundary conditions general closed – form solutions are given of a thermoelastic rectangular plate with various elementary boundary conditions on each of the four edges. appendix a collect some important combinations of end boundary conditions. [let the plate be placed in a coordinate system with the origin at it center and the edge width (a) be parallel to x – axis and and the edge width (b) be parallel to y as in fig. (1) 4. natural frequency and mode shape of dynamic thermoelastic plates free, transverse vibrations of the thermoelastic structural with neglecting the effect of in plane vibrations are studied with different end boundary conditions under uniform temperature distribuation. 4.1. all edges are simply supported the general governing differential equation of free vibration of thermoelastic plate is represented by [6]: …(1) where )1(12 2 3   eh d , and the quantities    2/ 2/ )( h h t dzten     2/ 2/ )( h h t zdztem  …(2) which represents the thermal stress resultants . then the boundary condit ions for the deflection w are represented in appendix c 00   axx ww , 00   byy ww 0 2 2 2 0 2        x w x w axx , 0 2 2 2 0 2        y w y w byy the initial conditions assuming the plate initially at rest in the refrence position ,are given by 0)0,,()0,,(     yx t w yxw ax 0 , by 0 …(3) the displacement function ),,( tyxw is approximated by means of the expansion [7]. natural frequency (hz) yx w n y w n x w n m whwd xyyx t             2 2 2 2 22 4 2 1    b wael r. abdul-majeed al-khwarizmi engineering journal, vol. 8, no.2, pp 1-11 (2012) 3 b yn a xm wt tyxwtyxw m n mn mn    sinsinsin sin),(),,( 1 1       …(4) and the displacement function ),( yxw is assumed from functions, that satisfies identically the boundary conditions; these functions are different due to the types of end conditions at x and y axis and this will be studied . the plate will have uniform temperature ctt  …(5) substitution of eq.(5) in eq. (2) we have ct ehtn  0tm …(6) so that for all edges are restrained   1 t yx n nn 0xyn …(7) with all edges are restrained ,substituting the thermal forces in eq. (7) and the deflection from eq. (4) into the governing differential equation of free vibration of thermoelastic plate in eq.(1) noting that 0mt , one obtains the following frequency equation.   222 2 2224 )()( 1 )()( mn t h b n a m v n b n a m d             …(8) for natuaral frequancy of plate without thermal load 0tn  2222 4 4 2 nrm ha d mnf     …(9) then )( )1( 222 2 2 22 nrm avh nt mnfmn       …(10) substituting eq. (7) into eq. (10) , the natuaral frequancy as a function of uniform temperature ct can be presented as )( )1( 222 2 2 22 nrm avh etc mnfmn       …(11) and for restrained edges at x=0,a and unrestrained at y=0,b thermal forces will be   1 t x n n 0 yxy nn …(12) and the natuaral frequancy will be 2 2 22 )1( avh mnt mnfmn     …(13) and the function of the uniform temperature ct will be 2 22 22 )1( av metc mnfmn      …(14) 4.2. all edges are clamped to derive the differential equation for lateral vibration of rectangular thermoelastic plate a kinetic energy of the plate in edition to the total strain energy of the plate and apply the hamilton's principle to derive the equation of motion. the kinetic energy due to the velocity w only is represented as  a dxdywht 2 2 1  …(15) the hamilton's principle for the plate undergoing small deflection can be set as [8]: 0)( 2 1  dtt t t strain …(16) then the lagrangian of the plate from the above equation can be written as   dxdywhdxdy y w x w v m dxdy y w x w n y w n x w ndxdy y w x w dl ra t xyy a x a                                                                 2 2 2 2 2 2 22 2 2 2 2 2 1 1 2 2 1 2 1  …(17) for free vibration the solution is assumed tyyxxatyxw ji m i n j ij sin)()(),,( 1 1     …(18) substituting eq. (18) by eq. (19) and minimizing the resulting lagrangian with respect to ija ,we get wael r. abdul-majeed al-khwarizmi engineering journal, vol. 8, no.2, pp 1-11 (2012) 4     ij a bm i n j a b t ij m k n j a b xyyx a b adxdyyxhdxdyyxyx v m a dxdyyyxxnyxnyxn dxdyyxyyxxyxd                                    0 0 222 1 1 0 01 1 0 0 2222 2222 0 0 )( )1( )2)(( )(2)(  …(20) this is the general frequency equation. with uniform temperature ct and all edges are restrained with the aid of eq. (2) for thermal forces and thermal moments into general frequency equation we have:              a b a a bb t dxdyyxh dxdyyxyx v n dxdyyxyyxxyxd 0 0 22 0 0 0 2222 0 2222 2 )()( )1( )(2)(   …(21) the frequency of plate without thermal effect has the form         a b a b ijf dxdyyxh dxdyyxyyxxyxd 0 0 22 0 0 2222 2 )(2)(   …(22) then with substituting the mode shape of clamped ends ix and jy from appendix c   )1(2 2 3 22 122 vha rnt ijfij       …(23) with ijf for free vibration of clamped plate   4 4 3 4 2 24 12 2 ha rrd ijf      ...(24) then ij terms of uniform temperature will be as:   )1(2 2 3 22 122 va retc ijfij       …(25) where 21, and 3 are calculated from appendix c for clamped edges restraind at x=0,a and unrestrained at y=0,b )1(2 2 122 vha n t ijfij      …(26) in terms of temperature )1(2 2 122 va etc ijfij      …(27) 4.3. edges are clamped at x=0,a and simply supported at y=0,b the general frequency equation of clamped edges eq. (20) are suitable for edges clamped at x=0,a and simply supported at y=0,b. with uniform temperature ct and all edges restrained with the aid of eq. (2) for thermal forces and thermal moments into general frequency equation and arranged with substituting the mode shape of two clamped ends and two simply supported ends ix and jy from appendix c into above equations the result will be   )1(2 2 3 22 122 vha rnt ijfij       ...(28) with ijf for free vibration suitable for edges clamped at x=0,a and simply supported at y=0,b .   4 4 3 4 2 24 12 2 ha rrd ijf      …(29) then ij in terms of uniform temperature will be:   )1(2 2 3 22 122 va retc ijfij       …(30) where 21, and 3 calculated from appendix c for clamped edges restraind at x=0,a and simply supported unrestrained at y=0,b )1(2 2 122 vha nt ijfij      …(31) in terms of temperature wael r. abdul-majeed al-khwarizmi engineering journal, vol. 8, no.2, pp 1-11 (2012) 5 )1(2 2 122 va etc ijfij      …(32) 5. results and discussions the sample of calculations was made on aluminum 1060-h18 rectangular plate which has the mechanical and thermal properties given in appendix a respectively. rectangular plate with three aspect ratio a/b (r = 1.2). and a/h ( =120) and owing constant magnitude of a=0.12 m has been considered. the effects of the uniform increase of temperature of plates (thermoelastic behavior) on the natural frequency and mode shapes with different three types of ends conditions have been studied. figures (2), (3) and (4) show the effect of temperature rising on natural frequencies analytical magnitudes till it reaches the thermal buckling temperature for plates with all edges restrained. the types are ssss, cccc and cscs respectively it is observed that the lowest natural frequencies of all types reach zero when the temperatures get to the thermal buckling temperature; also the first five natural frequencies of plates decreas with increasing the temperature. second and third natural frequencies of cscs plate have the same magnitudes almost. figures (5), (6) and (7) show the effect of temperature rising on natural frequencies analytical magnitudes till it reaches the thermal buckling temperature for plates with edges at x=0,a restrained the types are ssss, cccc and cscs respectively the lowest natural frequencies of all types reach zero when the temperatures has the thermal buckling temperature. the first five natural frequencies of plates decrease with increasing the temperature. the fifth natural frequency of ssss plate will become the fourth natural frequency and vice versa when the temperature has magnitude close to 6 c 0 . also cccc natural frequencies have the same behavior of ssss type but they are switching at magnitude close to 3 c 0 . cscs natural frequencies have the switching behavior between second and third natural frequencies at magnitude close to 1 c 0 . fig. 2. effect of temperature on first five natural frequencies magnitude on ssss plate, all edges are restrained. 4s r =1.2 0 200 400 600 800 1000 1200 1400 1600 1800 2000 4.5813 4.5 4 3 2 1 0 t (c) natural frequancy (hz) mode 1,1 mode 2,1 mode1,2 mode 2,2 mode 3,1 ssss wael r. abdul-majeed al-khwarizmi engineering journal, vol. 8, no.2, pp 1-11 (2012) 6 fig. 3. effect of temperature on first five natural frequencies magnitude on cccc plate with all edges are restrained. fig. 4.effect of temperature on first five natural frequencies magnitude on cscs plate, all edges is restrained. ssss r =1.2 0 200 400 600 800 1000 1200 1400 1600 1800 2000 11.17831086420 t (c) na tu ra l f re qu an cy (h z) mode 1,1 mode 2,1 mode1,2 mode 2,2 mode 3,1 fig. 5.effect of temperature on first five natural frequencies magnitude on ssss plate, edges at y=0, b are unrestrained. cscs 0 500 100 150 200 250 5.47 5 4 3 2 1 0 t (c) natural frequency (hz) mode 1,1 mode 1,2 mode2,1 mode 2,2 mode 3,1 natural frequancy (hz) 4c r =1.2 0 50 1000 1500 2000 2500 6.86.5 6 5 4 2 0 t (c) natural frequancy (hz) mode 1,1 mode 2,1 mode1,2 mode 2,2 mode 3,1 wael r. abdul-majeed al-khwarizmi engineering journal, vol. 8, no.2, pp 1-11 (2012) 7 fig. 6.effect of temperature on first five natural frequencies magnitude on cccc plate, edges at y=0, b are unrestrained. fig. 7. effect of temperature on first five natural frequencies magnitude on cscs plate, edges at y=0, b are unrestrained. 6. conclusions the following are the main summarized conclusions of this paper: 1. thermal stresses have a significant influence on the natural frequency for the free boundary conditions compared with clamped boundaries, so that the boundary condition is one of the important factors that influence the vibration and mode shapes. 2. the lowest natural frequencies of all types reach zero when the temperatures has the thermal buckling temperature 3. the first five natural frequencies of plates decreasing with increasing of the uniform temperature of the plates for all types of ends conditions 4. in the case of the two opposite edges which are unrestrained, there is a switching between the modes of natural frequency when the temperature increases for each type of ends conditions. nomenclature latin symbols a area (mm 2 ) a, b plate side length (mm) d flexural rigidity of an isotropic plate (n.mm) e modulus of elasticity of isotropic material (n/mm^2) 2c2 r 0 500 100 150 200 250 8.9468 7 6 4 2 0 t (c) natural frequency (hz) mode 1,1 mode 1,2 mode 2,1 mode 2,2 cscs mode 3,1 cccc 0 50 1000 1500 2000 2500 6.86.6 5 4 2 0 t (c) natural frequency (hz) mode 1,1 mode 2,1 mode1,2 mode 2,2 mode 3,1 wael r. abdul-majeed al-khwarizmi engineering journal, vol. 8, no.2, pp 1-11 (2012) 8 h plate thickness (mm) i ,j integer mt thermal bending moment (n.m) m,n integer nx, ny edge forces per unit length (n/m) nxy shearing forces per unit length (n/m) nt thermal forces per unit length (n/m) r dimensional aspect ratio a/b (m/m) t temperature (c 0 ), kinetic energy of the element (j) t time (sec) x, y, z cartesian coordinates greek symbols nm  , coefficients  poisson’s ratio  mass density (kg/mm^3) strain strain energy stored in complete plate (j) ijijf  , angular frequency without and with thermal effect (rad/s)  dimensional aspect ratio side / thickness (m/m)  coefficient of thermal expansion (1/c 0 ) w deflection (mm) abbreviations symbols cccc clamped-clamped-clamped-clamped cscs clamped-simply-clamped-simply ssss simply-simply-simply-simply 7. refrences [1] malak naji ,m. al-nimr and naser s. alhuniti “thermal stresses in a rapidly heated plate using the parabolic two-step heat conduction equation “ journal of thermal stresses, 24:399-410, 2001 taylor & francis [2] naser s. al-huniti, m. a. al-nimr and m. m. meqdad “thermally induced vibration in a thin plate under the wave heat conduction model” journal of thermal stresses, 26: 943–962, 2003 taylor & francis inc [3] a. n. norris and d. m. photiadis “thermoelastic relaxation in elastic structures, with applications to thin plates” arxiv: cond-mat/0405323 v2 20 nov 2004 [4] t.q.n. tran a, h.p. lee a,b, and, s.p. lim a “structural intensity analysis of thin laminated composite plates subjected to thermally induced vibration” composite structures. article in press. [5] william l. ko “predictions of thermal buckling strengths of hypersonic aircraft sandwich panels using minimum potential energy and finite element methods “, nasa technical memorandum 4643, may 1995 [6] v. i. kozolv "thermoelastic vibrations of arectangular plate" pirk. mekh. ,vol. 8, pp. 445-448, april 1972 [7] j. s. rao, "dynamics of plates", narosa publishing house, 1999. [8] a. w. leissa, "recent research in plate vibrations", complicating effects ,shock & vib. digest vol. 19, no. 3, 1987 . wael r. abdul-majeed al-khwarizmi engineering journal, vol. 8, no.2, pp 1-11 (2012) 9 appendices appendix a some combinations of end boundary conditions deflection mid-plane deformation symbol clamped restrained unrestrained supported restrained unrestrained free restrained unrestrained appendix b mechanical properties of aluminum 1060-h18 thermal properties of aluminum 1060-h18 heat capacity 0.9 j/g °c thermal conductivity 233 w/m °c coefficient of thermal expansion 2.34e-5/°c convection coefficient 2.5 w/m² °c appendix c for ssss ends condition xx ii sin , yy jj sin 00   axx ww , 00   byy ww , 0 2 2 2 0 2        x w x w axx , 0 2 2 2 0 2        y w y w byy density 2705 kg/m³ hardness, brinell 35 ultimate tensile strength 27 mpa tensile yield strength 20 mpa elongation at break 6 % modulus of elasticity 69 gpa poisson's ratio 0.3 fatigue strength 44.8 mpa machinability 30 % shear modulus 26 gpa shear strength 75.8 mpa q wael r. abdul-majeed al-khwarizmi engineering journal, vol. 8, no.2, pp 1-11 (2012) 10 for cccc ends condition )cosh(cossinhsin xxxxx iiiiii   )cosh/(cos)sinh(sin aaaa iiiii   )cosh(cossinhsin yyyyy jjjjjj   )cosh/(cos)sinh(sin bbbb jjjjj   00   axx ww , 00   byy ww , 00        x w x w axx , 0 0        y w y w byy for scsc ends condition )cosh(cossinhsin xxxxx iiiiii   )cosh/(cos)sinh(sin aaaa iiiii   , yy jj sin 00   axx ww , 00   byy ww , 00        x w x w axx , 0 2 2 2 0 2        y w y w byy where ai and bj are the roots of the above equations the roots of ssss ends condition are a m i    , b n i    the roots of cccc ends condition are for i=1 , j=2,3,4,…. for i=1 , j=1 )2(3.12 37.4 )5.0( 112 3 1       i for i=2,3,4,… j=1 )2()2( )5.0( )5.0( 33112 3 1       j i for i=2,3,4,. j=2,3,4,….\ )2()2( )5.0( )5.0( 33112 3 1       j i for i=2,3,4,. j=2,3,4,…. the roots of cscs ends condition are for i=1 , j=1, 2, 3,.. 22 112 3 1 )2( )5.0(    j j i    for i=2,3,4,… j=1,2,3…. q q 3.151 73.4 2 31     )2(3.12 )5.0( 73.4 332 3 1       j 22 2 3 1 3.12 73.4    j j    (2012 )1 11 ، صفحت2، العذد 8 مجلت الخىارزمي الهىذسيت المجلذوائل رشيذعبذ المجيذ 11 حاثير الحافاث المحذدة مه الحركت على ديىاميكيت الصفائح المروت حراريا ححج ظروف وهاياث مخخلفت ***عذوان واجي جميل** محسه جبر جىيج* وائل رشيذ عبذ المجيذ جايؼت بغذاد/ كهٍت انهُذست انخىاسصيً/ قسى هُذست انًٍكاحشوَكس* جايؼت انُهشٌٍ/ كهٍت انهُذست ** جايؼت بغذاد/ كهٍت انهُذست/ قسى انهُذست انًٍكاٍَكٍت*** الخالصت كم , كم انُهاٌاث راث اسُاد بسٍط : صٍغ يؼادنت انخشدد انطبٍؼً نصفائح يسخطٍهت انشكم يغ وبذوٌ حاثٍش انًشوَت انحشاسٌت نحاالث انُهاٌاث انخانٍت انُهاٌاث يثبخت , و َهاٌخٍٍ يخقابهخٍٍ باسُاد بسٍط وَهاٌخٍٍ يثبخخٍٍ حى اٌجادها يٍ خالل انحم بانطشٌقت انًباششة نهُهاٌاث باسُاد بسٍط , وباسخخذاو يباديء حاثٍش حثبٍج انُهاٌاث افقٍا بىجىد دسجت حشاسة يُظًت انخىصٌغ ػهى انخشدداث انطبٍؼٍت . هايهخىٌ وانخخفٍض بطشٌقت سحض نهطاقت انكهٍت نباقً اَىاع انُهاٌاث وشكم انخشدد حى دساسخها كًا حى انخؼشف ػهى حاثٍش حىنذ االجهاداث انحشاسٌت انُاحجت يٍ حثبٍج انُهاٌاث افقٍا ػهى خىاص االهخضاصاث وحى يالحظت اٌ االجهاداث انحشاسٌت انًخىنذة حضداد يغ اصدٌاد دسجت حشاسة انخسخٍٍ وهزا ٌىدي انى َقصاٌ فً انخشدداث انطبٍؼٍت نكم اَىاع انُهاٌاث ونكم اشكال انخشدداث .انطبٍؼٍت final zainab ziad ismail / al-khwarizmi engineering journal ,vol.1, no. 1,pp 117-124 (2005) ١١٧ al-khwarizmi engineering journal al-khwarizmi engineering journal, vol.1, no.1,pp 117-124, (2005) removal of oil from wastewater using walnut-shell dr. zainab ziad ismail environmental engineering dept/college of engineering./university of baghdad abstract the ability of pulverized walnut-shell to remove oil from aqueous solutions has been studied. it involves two-phase process which consists of using walnut-shell as a filtering bed for the accumulation and adsorption of oil onto its surface. up to 96% oil removal from synthetic wastewater samples was achieved while tests results showed that 75% of oil can be removed from the actual wastewater discharged from alduara refinery in the south of baghdad. keyword: wastewater, oil removal, walnut-shell, adsorption. introduction fats, oils and greases (fog) content of wastewater can cause many problems in both sewers and waste treatment plants. if oil or grease is not removed before discharge of the waste it can interfere with the biological life in the surface wasters and create unsightly floating matter and films [1]. the acute effects of oils on birds, fish and microorganism are reasonably well cataloged. the potentially more harmful is the subtle effect on other aquatic life [2]. the food industry seeks effective technologies to remove fats, oils and greases. manufactures of oilcontaining foods face the problem of reducing the oil containment load to downstream wastewater systems. a large amount of water is used in the refinery processes and a big fraction of it comes out as waste after getting polluted by oil which enters into the wastewater from leaks, spills etc., at various stages [3]. methods of separating fog from water include physical and/or chemical separation. in physical separation, free fog is separated according to differences in specific gravity or in surface tension phenomena. in chemical separation, dispersed water droplets and solids are destabilized through the use of chemicals. dissolved air flotation (daf) is a well-accepted method of fog removal in the meat and diary industries. through the addition of coagulants and flocculants, very effective separation is achievable. however, the coagulants and flocculants are fairly expensive and alter the composition of retained fats and solids so that reuse as animal food is sometimes not possible. ultrafilteration (uf) membranes work very well on filtering out fog. oil in water from can-washing operations also has been removed by membranes. membrane configurations for fog separation include flat sheet, tubular, hollow fiber, or spiral wound design [4]. zainab ziad ismail / al-khwarizmi engineering journal ,vol.1, no. 1,pp 117-124 (2005) ١١٨ other techniques have been attempted with less success, including combinations of lignin or halogen with natural or synthetic polymers; have been recently patented as agents to facilitate separation of fog from food processing wastewater [5]. a new pressurized thermal technology for separating oil/water emulsions can have application to food processing fog. this technology uses the change in physical properties and surface tension of water and fog at elevated temperature up to 3000c at pressures of 100 atmospheres to break the emulsion and allow recovery of separate oil and water streams for reuse or recycle [6]. one oxidation system, wet air oxidation, has already reported for olive mill wastewater treatment, but was found satisfactory only in combination with biotreatment. electro-flotation seems to be an excellent method for obtaining high retention of fog. in this method fog emulsions are broken under the effect of electric field. most refineries and many chemical plants use oil-water separation devices as api separators, corrugated plate interceptors (cpi), sometimes called titled plate interceptors (tpi). (cpis) are widely used for oil-water separation in many industries, but have found only limited acceptance in refineries. the reason is that the units cannot take shock loads and high flows as well as a conservatively designed api separator [7]. walnut-shells were originally developed for cleaning gasoline and diesel engines due to its lack of silicon and toughness. one of the most popular uses is the deflashing of molded plastic parts. a typical ph and moisture content values available for walnut-shells are as follows [8]: ph: 5.4 4.5 moisture: 4.5% activated carbon can be prepared from walnut shell which is chemically activated by zinc chloride. it is observed that a the ratio of activating agent to raw material increases to 100%, a sharp enhancement of surface area and pore volume of activated carbon product results[9]. walnut-shell filtration was developed as a more suitable method for filtering oil and suspended solids in the applications where sand filters were conventionally used. it is used to treat refinery wastewater, oil field produced water, steel mill direct spray and caster water, ethylene plant quench water, copper concentrate decant and oily water [10]. the main objectives of this research are the following 1-improves the potential of using natural products in the environmental applications to avoid side effects of using synthetic chemical materials. 2-study the efficiency and mechanism of oil removal from wastewater using walnut-shell. experimental materials pulverized walnut-shell was used in this study. it was obtained from peeling the walnut fruits which was supplied from the local market. the hard external peels were milled and then sieved into different particle sizes with maximum diameter of 850 µm. the sieved pulverized walnut-shell was washed with distilled water for dust and fine removals, then heated at 1050c for 24 hours and stored in a desiccator until required for use. the effluent used in this work was obtained freshly from the discharge point of the api unit in the treatment plant of alduara refinery in baghdad/iraq. the quality of this effluent is presented in table 2. zainab ziad ismail / al-khwarizmi engineering journal ,vol.1, no. 1,pp 117-124 (2005) ١١٩ another set of experiments were performed with oily aqueous solutions prepared by adding cooking oil (sun flower oil) in potable water to obtain synthetic oily aqueous samples of oil content 50 mg/l as a stock solution, subsequent concentrations of 40, 30, 20, 10 mg/l were made by dilution. all the materials used in this research are supplied by iraqi locally market. oil specifications as represented the turkish manufacturer (trade mark cezer) of the sun flower oil are shown in table1. table 1 specifications of sun flower oil given by the turkish manufacturer constituents average composition / 100 grams energy 884 kcal protein 0 g unsaturated 87.5-91.3 g saturated 8.7-12.5g carbohydrate 0 g cholesterol 0 g sodium 0 g vitamin 3 mg analysis table 2 represents the quality of the freshly collected actual samples. all measurements were carried out in accordance with the quantitative analysis methods described in the standard methods for examination of water and wastewater [11]. table 2 average composition of the freshly collected actual samples. constituen ts unit s concentrati on range aver age conce ntrat ion ph 7-7.5 7 cod mg/ l 200-600 400 suspended solids = 40-100 75 oil & grease = 8-12 10 phenol = 0.9-1.5 1 ph and suspended solids measurements were done by the researcher, whereby cod and phenol analysis were carried out in the service laboratory / department of chemistry / faculty of science / university of baghdad. oil and grease contents were performed in the laboratories of ministry of environment. shimadzu model uv-160 spectrophotometer was used to determine the concentrations of phenol which absorb ultraviolet radiation at λmax= 270 nm [12]. all reagents used in the analyses of wastewater samples were of analyticalreagent grade. the ph of solutions was measured by a ph meter of swiss made (type: methrihm 605). experimental procedure three sets of batch tests were performed in this study with oily samples each of 100 ml volume. the first set of experiments were conducted with the laboratory prepared samples containing 10 mg/l initial concentration of cooking oil (sun flower oil) were introduced into pyrex stoppered bottles containing accurately weighed amounts of pulverized walnut-shell ( 1, 2, 3, 4 and 5 g ). the bottles were shaken at room zainab ziad ismail / al-khwarizmi engineering journal ,vol.1, no. 1,pp 117-124 (2005) ١٢٠ temperature (25 ± 2º c) and allowed sufficient time up to 48 hours to reach equilibrium. by the end of each run, the reaction mixtures were filtered and the filtrate was analyzed for determination of equilibrium concentrations. control solution was similarly treated, without walnut-shell as a blank solution. residual concentration of the blank solution was taken as the initial one. another set of experiments were conducted with freshly collected oily samples from alduara refinery effluent. the third set of the laboratory batch tests carried out by mixing and shaking the laboratory prepared samples of different initial concentrations of cooking oil (50, 40, 30, 20 mg/l) with fixed amount (4 g) of pulverized walnut-shell and allowed to reach equilibrium. adsorption isotherm was obtained by plotting the amount of oil adsorbed per mg pulverized walnutshell verses the corresponding equilibrium concentration. results & discussion quality of the treated samples table 3 represents the quality of the treated oily samples and percentage removal of the pollutants. it can be seen that the maximum percentage adsorption of oil in synthetic solution is 96%. this occurs when the initial concentration of oil is 10 mg/l. table 3 specifications of the treated effluent samples constituents units average concentration percen tage reduct ion of polluta nts % prepared samples oil & grease mg/l 0.4 96 actual samples ph 7 cod mg/l 75 81.25 suspended solids = 30 60 oil & grease = 2.5 75 phenol = 0.1 90 for the freshly collected actual samples of wastewater the percentage adsorption of oil decreased to 75%. this may be attributed to the existence of other pollutants like phenol rather than oil that could be adsorbed by the walnut-shell particles. as represented in this table the phenol, chemical oxygen demand (cod) and suspended solids show good percentage reduction in their concentrations of 90%, 81.25% and 60% respectively. oil molecules may be arrested due to physical adsorption represented by electrokinetic forces which seems to be the most governing mechanism in this process. the space between the walnut-shell grains act as a sedimentation tank in which the suspended matter settles upon the walnut-shell particle. effect of walnut-shell doses on adsorption the percentage adsorption of oil at different walnut-shell doses is shown in figure 1. it can be seen from this figure that the percentage adsorption of oil increases and reaches a maximum value of 96% at 4 g of zainab ziad ismail / al-khwarizmi engineering journal ,vol.1, no. 1,pp 117-124 (2005) ١٢١ walnut-shell particles and remains constant for synthetically prepared waste samples; whereas the percentage adsorption of oil in actual waste samples increases with the increase of adsorbent doses and reaches the maximum value of 75% since the initial oil concentration was 10 mg/l reduced by adsorption to 2.5 mg/l in the treated effluent samples as shown in table 3. the increase in percentage adsorption may be related to the fact that the number of available adsorption sites increases by increasing the adsorbent doses and that results in the increase of the oil removal efficiency. pulverized walnut-shell dose (g) a ds or pt io n % 50 60 70 80 90 100 0 1 2 3 4 5 prepared samples actual samples figure 1. percentage adsorption of oil in synthetic and actual waste samples of initial oil concentration of 10 mg/l with different pulverized walnut-shell doses effect of time on adsorption figure 2 represents the effect of time on the adsorption process for both synthetic and actual samples. as represented by these plots, adsorption at equilibrium conditions were attained after a contact time of 24 hours for both types of samples. time (h) x (m g) 0 2 4 6 8 10 0 10 20 30 40 50 actual samples prepared samples figure 2. effect of time on the adsorption of oil in actual samples adsorption isotherm figures 3 and 4 represent the adsorption isotherm of oil on pulverized walnut-shell and the linearized plot of langmuir isotherm respectively. ce (mg/l) c s 0.000 0.002 0.004 0.006 0.008 0.010 0 4 8 12 16 figure 3. adsorption isotherm of oil on pulverized walnut-shell at 25º c ce (mg/l) c e/c s ( m g/ l) 0 400 800 1200 1600 2000 0 4 8 12 16 ce/cs=76.724+111.221ce r= 0.9949 figure 4. linearized plot of langmuir isotherm zainab ziad ismail / al-khwarizmi engineering journal ,vol.1, no. 1,pp 117-124 (2005) ١٢٢ as shown in figures 3 and 4, adsorption isotherm of oil particles shows a good agreement with the typical langmuir isotherm plot and those encountered in the adsorption of most organic compounds from dilute aqueous solutions. this plot shows that, as the concentration of oil is increased in the liquid phase, proportionality more of the adsorbent surface is covered with oil at higher concentration of the material in the solution phase, the adsorbent is completely based on the assumption that a single monolayer of oil accumulates at the solid phase. the langmuir data demonstrates that walnut-shell is an effective adsorbent for oil. the results indicate a good positive applicability of the langmuir model. the correlation coefficient was found to be 0.9949. the equation that describes the langmuir system is represented by equation (1) and its linearized form equation (2) [13]. e e s bc1 abc m xc + == ……… (1) e e c a 1 ab 1 x/m c += ……… (2) to obtain the sorption characteristics of the system, the laboratory study was followed by bestfit analysis of the sorption isotherm model. the empirically determined langmuir equation given by equation (3), was used to find the isotherm constant (a) and the saturation coefficient (b) of oil as a relevant adsorbate as follows: e s e 111.221c76.724 c c += …… (3) a = 0.009 b = 1.45 l/mg the effect of isotherm shape effect on whether the adsorption is favorable or not the following formula has been used [12]: oac1 1r + = ……… (4) it is a favorable adsorption for values of r less than 1. for values greater than 1 it is unfavorable. for this system including both synthetic and actual oily samples with initial oil concentration of 10 mg/l, the adsorption was found to be favorable since the separation constant r is equal to 0.9. conclusion this study shows the potential of walnut-shell application for the oil removal from wastewater. the results revealed that during the filtration process, adsorption was taking place on the active surfaces of walnut-shell particles. the langmuir constants and the constant separation factor have been determined. the percentage removal of oil from synthetic and actual wastewater was 96% and 75% respectively. the beauty of the walnutshell application for oil removal from wastewater is that it is ecologically sound and environmentally desirable treatment technique. in large scale application of this technique it is recommended to use a complementary scrubbing system to improve the backwashing process. further work is recommended to study the column tests system. zainab ziad ismail / al-khwarizmi engineering journal ,vol.1, no. 1,pp 117-124 (2005) ١٢٣ references 1metcalf & eddy, inc. wastewater engineering. t m h edition, tata mcgraw-hill publishing company itd new delhi, pp. 239-240, 1974. 2vesilind, p.a.et.al. environmental pollution and control.3rd edition. butterworth-heinemann, a division of reed publishing (usa) inc., pp. 18, 1990. 3rao, m.n. & datta, a.k., wastewater treatment, 2nd edition, oxford & ibh publishing co.pvt.ltd, pp. 303, 1987. 4shih, j.c.h. and kozink, m.b., ultrafilteration treatment of poultry processing wastewater and recovery of a national of a nutritional by product, poultry science, 59:247-252, 1980. 5miller, j.c., process for removing proteinaceous materials, fats and oils from food processing wastewater and recovering same. u.s. patent 5,413,720, may 9, 1995, and u.s. patent 5,543,058, august 6, 1996. 6sealock, l.j., treatment methods for breaking certain oil and water emulsions. u.s. patent 5,100,559, march 31, 1992. 7stephenson, r.l. & blackburn, j.b. the industrial wastewater systems handbook. lewis publishers, usa, pp. 130-137, 1998. 8walnut shell abrasives, carriers, & media offer from reade advanced materials, pp. 1-3, 1997. 9m. abedinzadegan abdi, m. mahdyarfar, a. m. raqshidi, a. ahmadpourr, preparation of activated carbon from chemical activation of walnut shell, jor. of faculty of engineering, ferdowsi university of mashhad, 14, (1), pp. 1-13, 2002. 10special report. environmental processes, 98, hydrocarbon processing, 77, (8), pp.72-110, 1998. 11standard methods for the examination of water and wastewater. 15th edition, american public health association, 1980. 12mckay, g., bino, m.j. and altamemi, a.r., the adsorption of various pollutants from aqueous solutions on to activated carbon, water research, 19, (4), pp. 491-495, 1985. 13watts, r., j., hazardous wastes, sources, pathways, receptors, john wiley & sons, inc, pp. 267-271, 1997. nomenclature ce= equilibrium concentration of pollutant in solution after adsorption (mg/l) co= initial concentration of pollutant (mg/l) x = adsorbed contaminant concentration cs= x/m contaminant concentration adsorbed per unit weight of adsorbent(mg/mg) a = empirical constant b = saturation coefficient (l/mg) r = dimensionless constant separation factor zainab ziad ismail / al-khwarizmi engineering journal ,vol.1, no. 1,pp 117-124 (2005) ١٢٤ ازالة الزيوت من المياه الملوثة بها باستخدام قشور ثمار الجوز زياد اسماعيل زينب.د جامعة بغداد /كلية الهندسة/قسم هندسة البيئة :الخالصة ة الزيوت من المياه الملوثة تم في هذا البحث دراسة قابلية مسحوق قشور ثمار الجوز في إزال مسـحوق (تتضمن عملية اإلزالة وجود طورين هما الطور السائل الملوث بالزيت والطور الصلب . بها تم استخدام مجموعتين من النماذج المائية الملوثة . الذي يتم تراكم وامتصاص الزيت عليه) قشور الجوز ة مختبريا وقد بلغت نسبة إزالة الزيت مـن هـذه األولى محضر المجموعة, بالزيت في التجارب العملية أما المجموعة الثانية فهي نماذج حقيقية تم جمعها من مياه الصـرف الصـناعية فـي %. ٩٦النماذج %٧٥د بلغت نسبة إزالة الزيت منها مصافي الدورة جنوب بغداد وق (microsoft word \345\324\307\343 \332\307\325\35518-10) al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 14, no. 1, march, (2018) p.p. 10-18 experimental investigation of the effect of curvature ratio on heat transfer in double pipe helical heat exchanger hisham assi hoshi department of electromechanical engineering/ university of technology/ baghdad/ iraq. email: hah_62@yahoo.com (received 27 april 2017; accepted 3 august 2017) https://doi.org/10.22153/kej.2018.08.001 abstract different parameters of double pipe helical coil were investigation experimentally. four coils were used; three with a curvature ratio (0.037, 0.031, and 0.028) and 11mm diameter of the inner tube while the fourth with 0.033 curvature ratio and 13 mm diameter of the inner tube. the hot water flow in the inner tube whereas the cold water flows in the annulus. the inlet temperatures of hot and cold water are 50 0c and 18 0c respectively. the inner mass flow rate ranges from 0.0167 to 0.0583 kg/s. the results show the nusselt number increase with increase curvature ratio. the nusselt number of the coil with 0.037 curvature ratio increases by approximately 12.3 % as compare with 0.028 curvature ratio. the results also reveal that the nusselt number of the coil with curvature ratio 0.033 increases by approximately 11.6 % as compare with 0.028 curvature ratio for 400 mm coil diameter. keywords: curvature ratio, dean number, heat transfer, helical coil. 1. introduction one of most favorable passive techniques is helical coiled. the secondary flow motion induced due to centrifugal force resulting from the curvature of the tube makes the heat transfer rate greater than in a straight tube [1, 2, and 3]. the heat transfer and flow characteristic in curved tubes such as spiral and helical coiled tubes have been investigated. jamal-abad et al [4] have studied experimental investigation on heat transfer performance and pressure drop characteristics in spiral coil. they found that the geometry of spiral coil is much effective in enhancing the thermal performance. kubir and kuloor [5, 6] found that friction factor in spiral coil greater than that in straight tubes. rennie [7] and rennie and raghavan [8] experimentally studied the heat transfer in double-pipe helical heat exchanger comprised of one loop. they showed that the overall heat transfer coefficient increase with increase in tube dean number or annulus dean numbers. kumer et al [9] numerically and experimentally investigated the heat transfer in double-pipe helical heat exchanger comprised of four turns of coils. they found that the numerical results of friction factor agree fairly well with the experimental data and an error of 5-8% was observed. also annulus nusselt number values increases with increase in the annulus flow rate. the heat transfer characteristic in helical coiled tubes with different design parameter such as tube diameter, coil diameter and coil pitch have rarely been investigated experimentally and numerically [10, 11, 12 and13]. mohammed et al [14] performed a numerical study to investigate the heat transfer and fluid flow characteristics in a helical coiled tube heat exchanger using finite volume method. the study was carried out with different geometrical parameter. the results show that the geometrical parameters such as the helix radius and inner tube diameter have significant effect on the heat transfer under laminar flow conditions. akhavanbehabadi et al [15] hisham assi hoshi al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 1018 (2018) 11 investigated experimentally the heat transfer characteristics of helically coiled tubes. the experiments were carried out for different geometrical parameter. it was concluded that the coils with greater curvature ratio had higher performance. pawar et al [16] study experimentally the heat transfer characteristics in a helically coiled heat exchanger for newtonian as well as non-newtonian fluids. the experiments were performed for different curvature ratio. they found that overall heat transfer coefficient is higher for smaller helix diameter as compared to larger helix diameter. in the present work four coils were considered; three coils with a curvature ratio (0.037, 0.031, and 0.028) and 11mm diameter of the inner tube while the fourth with 0.033 curvature ratio and 13 mm diameter of the inner tube and all with same coil length. the purpose of this work is to study the effect of curvature ratios and inner tube diameter on heat transfer and pressure drop characteristics in a helical double pipe heat exchanger and compare the result with previous work. 2. experimental set up and procedure 2.1. material the test section is a double pipe helical coil it was made of copper. four coils with different coil diameter (d�) were considered, each coil having 1260 mm long but the coil diameter were changed as shown in the figure (1). the inner diameter of outer pipe (d�) and inner diameter of inner pipe (d�) are 22 mm and 11 mm respectively for three coils and the fourth with 13 mm inner diameter of inner pipe (d�) and all with 1 mm thickness. the geometry dimensions were putting in table (1). 2.2. experimental apparatus the experimental set up mainly consist of a test section, hot water closed loop, cold water open loop as shown in the figure (2) and figure (3). the water is heated in hot tank by 3000 w thermostatic electrical heater then pumped to the inner helically coiled tube of test section for circulation, then returns to the hot tank. the cold water was driven by pump from the cold water tank to flow through annulus as counter flow configuration. two flow meter with rang (1-10 lit/min) with 0.2 % accuracy were used to measure the flow rate of hot and cold fluid .the flow rates were controlled by ball valve. the pressure drop through the inner tube was measured with mercury u-tube manometer. four t-type thermocouples with ±0.1 0c accuracy were inserted at inlet and outlet of the test section and connected to a digital temperature recorder to measure the cold and hot fluid temperature. the experimental were conducted by changing for six different flow rates in the inner tube from (1-3.5 lit/min) with annulus cold water flow rate was kept constant at 2 lit/min. the inlet hot water temperature was set to (50 ± 1 0c) whereas the inlet cold water was set to (18 ± 0.5 0c). the test section is isolated by rubber tube to minimize the heat losses with surrounding. 2.3. experimental procedure in the beginning, the heater is switch on to warm the water inside the hot tank and then the two pumps are turned on to allow hot and cold water to pass through the test section. the flow is adjusted through a control ball valve until flows reach an accurate value. then, until the system reaches a state of stability, we begin to take the readings of the inlet and outlet temperature of the water in the inner and annulus of test section. the measurement readings are repeated to make sure they are correct. six values of flow rate were considered from 1 lit/m to 3.5 lit/m and the experiments were repeated. 2.4. data reduction the heat transfer rate is averaged between the heat supplied by inner hot water and the heat absorbed by the annulus cold water q avg = �� �������,����,���� �������,����,�� � � ...(1) the overall heat transfer coefficient (�) is calculated as follow [17]: � = � !"�# …(2) where lmtd is ∆t&'() = �(*,+�(,,-���(*,-�(,,+� ./ 01*,+21,,-3 01*,-21,,+3 …(3) the inner side heat transfer coefficient (hi) is determined by neglecting the conduction thermal resistance of tube wall through. 4 5 = 4 6+ + 4 6 …(4) critical reynolds number is given as [18] 89:;<=<:>? = 20000 0b� #� 3 c.e� …(5) the outside heat transfer coefficient (ho) was estimated by correlation of rennie for laminar flow [7]. nu� = 6-)* h = 0.075de + 5.36 …(6) hisham assi hoshi al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 1018 (2018) 12 where the annulus dean number de is dn = opq 0)-r�)+ r )-�)+ 3 0)-�)+ s 3 4 �⁄ …(7) where d� is the inner diameter of outer pipe, d� is the outer diameter of inner pipe and r is the radius of coil. the hydraulic diameter d6 is d6 = d� + d� …(8) thus, nu� = )+6+ h ...(9) where k is calculated by using mean bulk fluid temperature (tv). tv = (+�(� …(10) table1, geometrical dimensions of double pipe helical coils. fig. 1. helical coils with different coil diameters. fig. 2. experimental rig. fig. 3. schematic of experimental rig. helical coil wx(yy) z[ (yy) l (mm) w\ (yy) δ= z[ w\ n pitch (mm) coili 22 11 1260 300 0.037 1.336 40 coilii 22 11 1260 350 0.031 1.146 40 coiliii 22 11 1260 400 0.028 1.003 40 coilv 22 13 1260 400 0.033 1.003 40 hisham assi hoshi al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 1018 (2018) 13 3. results and discussion fig (4) and fig (5) show the variation of pressure drop with inner mass flow rate and with different curvature ratio. the pressure drop increase with increasing mass flow rate because of increasing flow rate led to increase the turbulent between the fluid elements. also when the flow increases, the flow becomes more turbulent, resulting in the loss of a large amount of energy due to the conversion of the energy of the pressure into kinetic energy. also pressure drop increasing with increase curvature ratio because secondary flow intensifies in higher curvature ratio due to centrifugal force that led to increase the shear stress means that pressure drop will increase. the figure (5) shows at bigger diameter pressure drop reduces because pressure drops inversely proportion to the diameter tube and directly proportion to the velocity of flow which is responsible for lower pressure drop. fig. 4. variation of pressure drop with inner mass flow rate. fig. 5. variation of pressure drop with inner mass flow rate for 400 mm coil diameter fig (6) and fig (7) show the variation of overall heat transfer coefficient with mass flow rate and curvature ratio. the result show that increase overall heat transfer coefficient by increasing mass flow rate this can be attributed increasing the velocity of fluid flow that makes increasing of heat transfer coefficient. also overall heat transfer coefficient increase with increase curvature ratio because the secondary flow is more effective due to centrifugal force at higher curvature ratio. but when increase the coil diameter the turbulence due to the effect of curvature ratio disappear and the fluid flow through coiled tube changed to become such as the flow through straight tube which in turn decrease overall heat transfer. fig. 6. variation overall heat transfer with inner mass flow rate. hisham assi hoshi al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 1018 (2018) 14 fig. 7. variation of overall heat transfer coefficient with inner mass flow rate for 400 mm coil diameter. fig (8) and fig (9) depicted the variation of nussult number with mass flow rate and with different curvature ratio. the results show the nussult number increasing with increase of mass flow rate due to increase the turbulent between the fluid elements which will enhance the rate of heat transfer. also show nussult number increase with increase of curvature ratio because at the high curvature ratio increase the centrifugal force, which in turn led to increase the effect of secondary flow that increase the rate of heat transfer and as a result increase the nussult number. also secondary flow is more effective due to centrifugal force, which increases at higher mass flow rate. the nusselt number of the coil with curvature ratio 0.037 increases by approximately 12.3 % as compare with 0.028 curvature ratio. fig. 8. variation of nusselt number with inner mass flow rate fig. 9. variation of nusselt number with curvature ratio. from the figure (10), it was found that nussult number increase with increase diameter of tube, as known that the increasing diameter of tube led to increase of curvature ratio. this leads to further improved heat transfer and then increases the nusselt number because when the diameter of the tube is increased, the secondary flows will be stronger, and then more confused. the nusselt number of the coil with curvature ratio 0.033 increases by approximately 11.6 % as compare with 0.028 curvature ratio for 400 mm coil diameter, or in other words as a comparison between inner tube diameter of 13 mm and 11 mm for the same coil diameter. fig. 10. variation of nusselt number with inner mass flow rate for 400 mm coil diameter. hisham assi hoshi al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 1018 (2018) 15 fig (11) shows the comparison of the experimental work with the results of dravid et al correlation for laminar flow [19]. the dravid et el correlation of the nusselt number for helical coil can be expressed as follows nu = ]0.76 + 0.65√de_prc.4bc for 50 < de < 2000 where dn = re 0 e+ ), 3 c.c in this work a critical reynolds number approximate about 6943 and the maximum reynolds number is about 6765 at high mass flow rate so the flow is laminar. from the figure dean number slightly decreases with decreasing curvature ratio. the curvature ratio and the velocity of the flow are two factors to determine the dean number. this can be explained with higher velocity and higher curvature ratio which increases mixing effect due to intensify secondary flow which in turn enhances heat transfer. the deviation between nusselt number obtained from above correlation and experimental results for coil with 0.037 curvature ratio is about 5.7 %. fig. 11. variation of nusselt number with dean number. the experimental results of nusselt number are related with dean number and prandtl number through the following correlation: nu = 0.382dec.cg4prc.e where dn = re 0 e+ ), 3 c.c for the conditions; 320 ≤ de < 1295 and 4.2 ≤ pr < 4.8, curvature ratio 0.028 ≤ ( e+ ), ) <0.037 and 1930 ≤ re <6765 the results of the present correlation are depicted in figures (12) with a deviation of about ± 4 %. fig . 12. comparison between experimental data and predictions present correlation. 4. conclusion 1. pressure drop increase with increase curvature ratio 2. pressure drop decrease with increase inner tube diameter 3. over all heat transfer coefficient increase with increase curvature ratio 4. the nusselt number of the coil with curvature ratio 0.037 increases by approximately 12.3 % as compare with 0.028 curvature ratio in case of 11mm inner tube diameter. 5. the nusselt number of the coil with curvature ratio 0.033 increases by approximately 11.6 % as compare with 0.028 curvature ratio for 400 mm coil diameter. 6. the nusselt number obtained from dravid et el correlation and experimental results for coil with 0.037 curvature ratio were close to with deviation is about 5.7 %. notation average heat transfer (w) avgq hot air mass flow rate. (kg/s) hm cold water mass flow rate. (kg/s) cm specific heat of water. (kj/kg k) ccp specific heat of air. (kj/kg k) hcp tube length, (m) l thermal conductivity, (w/m k) k pressure drop, (n/m�) ∆p temperature (k) t prandtl number pr = q �o h pr reynolds number re = o p e q re hisham assi hoshi al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 1018 (2018) 16 mean velocity (m/s) v overall heat transfer coefficient(w/ m� k) u convective heat transfer coefficient(w/ m� k) h nusselt number nu surface area (m�) a greek symbols density, ( kg/me) ρ dynamic viscosity, (kg/m s) μ subscripts h hot h, i hot inlet h, o hot outlet c cold c, i cold inlet c, o cold outlet o outside i inside 5. references [1] s.a. berger, l. talbot, l.s. yao, flow in curved pipes annual review of fluid mechanics 15 (1983) 461–512. [2] d.g. prabhanjan, g.s.v. raghavan, t.j. rennie, comparison of heat transfer rates between a straight tube heat exchanger and a helically coiled heat exchanger international communications in, heat and mass transfer 29 (2) (2002) 185-191, [3] y.i.kim, s.h.kim, y.d.hwang, j.h. park, numerical investigation on the similarity of developing laminar flows in helical pipes,nucl.eng.des.241(12) (2011) 52115224. [4] m.t. jamal-abad, a. zamzamian, m. dehghan, experimental studies on the heat transfer and pressure drop characteristics of cu-water and al-water nanfluid in a spiral coil, experimantal thermal and fluid science 47 (2013) 206212. [5] v.kubair,n.r. kuloor, flow of newtonian fluids in archimedean spiral tube coil correlation of the laminar,transition and turbulent flows, indian j. technol.4 (1969) 38. [6] v.kubair, n.r. kuloor, heat transfer to newtonian fluid in coiled pipe in laminar flow, int. j. heat mass transfer 9 (1966) 63-75. [7] t.j.rennie, numerical and experimental studies of a double pipe helical heat exchanger, ph.d. dissertation, mcgill university, montreal, canada, (2004) [8] t.j.rennie, v.g.s.raghavan, experimental studies of a double-pipe helical heat exchanger, experimental thermal and fluid science 29 (2005) 919-924. [9] v.kumar, s.saini, m.sharma, k.d.p.nigam, pressure drop and heat transfer study in tubein-tube helical heat exchanger, chemical engineeringscience61 (2006) 4403-4416. [10] n.ghorbani, h.taherian, m.gorji, h.mirgolbabaei, an experimental study of thermal performance of shell-and-coil heat exchangers, int. comm in heat and mass transfer 37 (2010) 775–781. [11] m. moawed, experimental study of forced convection from helical coiled tubes with different parameters, energy conversion and management 52 (2011)1150–1156 [12] j.s.jayakumar, s.m. mahajani, j.c.mandal, k.n.iyer, p.k.vijayan, cfdanalysis of single-phase flows inside helically coiled tubes, computers and chemical eng. 34 (2010)430–446. [13] y.m.ferng, w.c.lin, c.c.chieng, numerically investigated effects of different dean number and pitch size on flow and heat transfer characteristics in a helically coil-tube heat exchanger, applied thermal engineering 36 (2012) 378-385. [14] h.a. mohammed, k. narrein, thermal and hydraulic characteristics of nanofluid flow in a helically coiled tube heat exchanger, international communications in heat and mass transfer 39 (2012) 1375–1383 [15] m.a. akhavan-behabadi, m.f. pakdaman, m. ghazvini, experimental investigation on the convection heat transfer of nanofluid flow inside vertical helically coild tubes under uniform wall temperature condition, international communications in heat and mass transfer 39 (2012) 556-564. [16] s.s. pawar , v. k. sunnapwar, experimental studies on heat transfer to newtonian and non-newtonian fluids in helical coils with laminar and turbulent flow experimental thermal and fluid science 44 (2013) 792– 804 hisham assi hoshi al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 1018 (2018) 17 [17] f.m. white, heat transfer, addison wesley publishing company inc., new york, ny, 1984. [18] seban, r.a., mclauchlin e.f. (1962), "heat transfer in tube coils with laminar and turbulent flow", heat mass transfer 6, 387395 [19] a.n. dravid, k.a. smith, e.w. merrill, p.l.t. brian, "effect of secondary fluid motion on laminar flow heat transfer in helically coiled tubes, american institute of chemical engineers journal 17 (5) 1971 1114-1112. )2018( 10-18، صفحة 1، العدد14دجلة الخوارزمي الهندسية المجلم هشام عاصي حوشي 18 نسبة األنحناء على انتقال الحرارة في مبادل حراري حلزوني مزدوج تحقيق عملي من تأثير األنبوب هشام عاصي حوشي التكنولوجية الجامعة / قسم الهندسة الكهروميكانيكية hah_62@hahoo.com البريد االلكتروني: الخالصة ملم قطر األنبوب 11) و 0.028 ,0.031 ,0.037مع نسبة انحناء ( ثالث .تم استخدام أربع لفائفو حلزونية مزدوجة األنبوبعدة عوامل متغيرة للفائف ملم قطر األنبوب الداخلي. يتدفق الماء الساخن في األنبوب الداخلي في حين يتدفق الماء البارد في 13نسبة انحناء و 0.033الداخلي في حين أن الرابع مع 0.0583إلى 0.0167على التوالي. ويتراوح معدل التدفق الكتلي الداخلي من c050 c018لقة. درجة حرارة مدخل الماء الساخن والماء البارد هي الح مقارنة مع % 12.3يزيد بحوالي 0.037كجم / ثانية . أظهرت النتائج زيادة عدد نسلت مع زيادة نسبة االنحناء. أن عدد نسلت من الملف نسبة انحناءه 0.028 هئمقارنة مع الملف نسبة انحنا % 11.6يزيد بحوالي 0.033كما كشفت النتائج أن عدد نسلت من الملف نسبة انحناءه . 0.028 الملف نسبة انحناءه .ملم 400لملف قطره final sadiq jaffar abass/al-khwarizmi engineering journal ,vol.1, no. 1,pp 61-72 (2005) ٦١ al-khwarizmi engineering journal al-khwarizmi engineering journal, vol.1, no.1,pp 61-72, (2005) stress analysis of the hip bone dr. akram abood jaffar* dr. sadiq jaffar abass ** huma mohamed abdullah* * human anatomy dept. / college of medicine / university of al-nahrain ** medical engineering dept. / college of engineering / university of al-nahrain abstract the bony pelvis has a major role in weight transmission to the lower limbs. the complexities of its geometric form, material properties, and loading conditions render it an open subject to biomechanical analysis. the present study deals with area measurement, and three-dimensional finite element analysis of the hip bone to investigate magnitudes, load direction, and stress distribution under physiological loading conditions. the surface areas of the auricular surface, lunate surface, and symphysis pubis were measured in (35) adult hip bones. a solid model was translated into ansys parametric design language to be analyzed by finite element analysis method under different loading conditions. the surface areas of the auricular surface, symphysis pubis, and lunate surface were (14.39±2.05cm², 4.46±1.01cm², and 24.63±3.2cm²) respectively. a significant positive linear relationship was found between the auricular surface area and that of the lunate surface. no such correlation was found between the auricular surface and symphysis pubis. the finite element analysis model showed that stresses, using the von mises method, were distributed mainly in the acetabulum (anterior, superior and posterior part: 11.2%, 5.4%, 15.9% respectively), auricular surface 24.6%, and ischial tuberosity 40.3%, when a 70kg load was applied. stresses calculated for higher loads showed a positive direct proportional increase. principle stresses indicated that failure occurred in the anterior and posterior surface of the acetabulum as well as in the sacrioiliac joint. keyword: hip bone, finite element analysis, stress. introduction: in the musculoskeletal system, some diseases are due to mechanical or are influenced in a positive or negative sense by mechanical factors. in every case, the balance between stressing and biological reaction of the tissues of the locomotor system plays a decisive role. a careful biomechanical analysis is therefore recommended at the beginning of any prognostical or therapeutical considerationi,ii. fracture risk is directly related to the ratio of tissue stress to tissue strength, which in turn is dependent on not only tissue composition but also tissue geometry and the direction and magnitude of loading. these three elements determine how the load is distributed within the tissueiiithe bony pelvis may be considered as two arches divided by a transacetabular plane (fig.1). the sadiq jaffar abass/al-khwarizmi engineering journal ,vol.1, no. 1,pp 61-72 (2005) ٦٢ posterior arch, chiefly concerned in transmitting weight, consists of the upper three sacral vertebrae and strong pillars of bone from the sacroiliac joints to the acetabular fossae. the anterior arch, formed by the pubic bones and their superior rami, connects these lateral pillars as a tie-beam preventing separation; it also acts as a compression strut against medial femoral thrustiv,v. when the weight of the body is being borne on both legs, the center of gravity is centered between the two hips and its force is exerted equally on both hips. under these loading conditions, the weight is supported equally on the femoral heads. in symmetrical standing on both lower extremities, the compressive forces acting on each femoral head represent approximately one-third of body weightvi,vii. in normal walking, the hip joint is subjected to wide swings of compressive loading from one-third of body weight in the double support phase of gait to four times body weight during the single leg support phase. many more detailed analyses of the biomechanics of the hip have been directed toward the stresses within the femoral stem than within the acetabulumviii,ix,x. the intact acetabulum is a horseshoe form that wraps around the superior, anterior, and posterior aspects of the slightly eccentric femoral head. the stress is transferred from the femoral head to the acetabulum through the anterior and posterior extensions of the horseshoexi,xii. finite element analysis (fea) is a computer-based numerical technique for calculating the strength and behaviour of structures, in which a structure is broken down into many small simple blocks or elements. the behaviour of an individual element can be described with a set of equations. just as the set of elements would be joined together to build the whole structure, the equations describing the behaviours of the individual elements are joined into an extremely large set of equations that describe the behaviour of the whole structure. the computer can solve this large set of simultaneous equations. from the solution, the computer extracts the behaviour of the individual elements. from this, it can get the stress and deflection of all the parts of the structure. the stresses will be compared to allow values of stress for the materials to be used, to see if the structures are strong enoughxiii. the use of fea in biomechanical research has been establishedxiv,xv,xvi,xvii. the present study deals with 3-d finite element analyses of the pelvic bone, which are used to investigate its basic load transfer and stress distributions under physiological loading condition methods: thirty-five adult hip bones of caucasoid origin were used. in each of them the surface areas of the auricular surface, lunate surface, and symphysis pubis were measured by a sheet of dental molding wax ('tenasyle'. associated dental products ltd, swindon, uk). when an accessory sacroiliac joint was observed the area of its articular surface was added to that of the auricular surface. each sheet was warmed gently until pliable on a thermostatically controlled electric hot plate. the sheet was then molded carefully to the contours of sadiq jaffar abass/al-khwarizmi engineering journal ,vol.1, no. 1,pp 61-72 (2005) ٦٣ each of the articular surfaces above. the wax was trimmed exactly on the articular margin (fig.2). the trimmed piece was then removed from the bone and weighed along with a reference piece of wax sheet of known area (900mm²=928mg). the area of the molded wax was calculated from these valuesxviii. one hip bone specimen was cross-sectioned to create a solid model constructed using 3d studio max5. the model obtained in this way reflects accurately the actual geometry of the hip bone. the 3d studio max5 program translated the data into ansys parametric design language (apdl) of ansys 5.4 (ansys inc.) finite element method program (fig.3). the model was meshed by using brick element with 8 nodes. the pelvis has been found to contain approximately 10% cortical bone and 90% cancellous bonexix,xx; from these percentages, a combined material property was assigned to the finite element model. the loading conditions in the hip joint are a complex problem. apart from the weight of the upper body, the muscles and ligaments forces operate onto the pelvis bone. for the sake of convention, the auricular surface was considered to be as an input area due to its role in load transmitting from the sacrum to the hip bone, and the lunate hip as an output area in which the forces will pass from the hip to the femur10. results: measurements of articular surfaces: an accessory sacroiliac joint was observed in 5% of the specimens (fig.4), whenever it was found its surface area was added to the auricular surface. table-1 shows the descriptive statistics of the articular areas of the hip bone. note that the mean area of the lunate surface was 10.24cm² more than the auricular area. the coefficient of variation for the articular surface areas was found to be 13%, 25%, 14% for the lunate, symphysis pubis and auricular surface respectively. (fig.5) shows the frequency distributions of the areas of the lunate and auricular surfaces. regression analysis of the areas of the auricular surface and the lunate surface showed a significant positive linear relationship (fig.6) with a correlation coefficient (r=0.56; p<0.0008). there was no correlation between auricular surface and symphysis pubis areas. model analysis by ansys: table-2 shows the summary of the calculated von mises stresses of the hip bone. on the lateral surface, the largest values of stresses for 70kg person were distributed in the anterior and posterior limbs of the acetabulum (11.2%, 15.9%) respectively (fig.7). by increasing the load, it was noticed that stresses will be distributed in the superior part of the acetabulum of a value (5.4%) (fig.8). the iliac crest, ramus of the ischium, body of the pubis, and inferior surface of the acetabulum had lower stresses compared with the previous regions. on the medial surface, the stress was (24.6%) in the auricular surface, (40.3%) in the ischial tuberosity, and (1.5%) in the ischial spine. by increasing loads these values increased. the iliac fossa, iliac crest, and body of the ischium have lower stress values. sadiq jaffar abass/al-khwarizmi engineering journal ,vol.1, no. 1,pp 61-72 (2005) ٦٤ discussion: the compressive force of the body weight that passes from the sacrum to the sacroiliac joint can be resolved into two components: one will go downward and laterally to the acetabulum, while the other component goes downward and medially to the symphysis pubis. the area of the articular surface relates to its ability to resist longitudinal compression forces provided its internal structure remains constantxxi. based on the above mechanical considerations, the transmission of compressive forces can be analyzed. our statistical analysis of the surface areas of the articulating surfaces emphasizes the fact that both the lunate and auricular surfaces are involved in force transmission through the hip bone while the symphysis pubis is merely a part of the anterior butressing arch of the articulating pelvis being involved in stability and protection. as far as the measurements of the surface areas of the articulating surfaces, this was indicated in the following: • the significant linear relationship between the areas of the auricular surface versus that of the lunate surface. no such relation was found between the auricular and symphysis pubis articular surfaces. • the coefficient of variation of the lunate and auricular surfaces were comparable (13% & 14%); whereas the coefficient was 25% for the symphysis pubis articular surface. since we cannot conclude anything by simple comparing the measures of absolute dispersion, the coefficient of variation (which is simply the standard deviation of a distribution expressed as a percentage of the mean) is the measure of the degree of relative dispersion that exists in the distributions. thus the distributions of the areas of the lunate and auricular surfaces are comparable on the contrary to that of the area of the symphysis pubis. this supports the idea that the lunate and auricular surfaces are being related in performing a joint task; that is of weight transmission. if we consider that, the mean surface area of the acetabulum (29.09cm2) represents 100% of the load passing out of the hip bone then 49% is received through the sacroiliac joint (14.35cm2). this difference indicates that magnitude of the load passing out from the acetabulum is more than that received at the sacroiliac joint. the possible reason for this is that some of the loads are applied to the acetabulum through other sources, mainly the ligaments. according to this, the ligaments play a very important role in weight transmission. ligaments act as strong mechanical beams and they are effective only when the ligaments are inclined toward the vertical direction; therefore, because the sacrospinous ligament is nearly horizontal it will not have that effect in carrying loads. thus, the most important ligament is the sacrotuberous ligament, which extends from ala of the sacrum downwards to the ischial tuberosity. the posterior sacroiliac ligaments are extremely thick and strong but contribute directly to sacroiliac joint stability. vertical loading (eg. weight bearing) produces a downward motion plus rotation. during normal standing, the upper body weight on the anterosuperior aspect of the sacrum sadiq jaffar abass/al-khwarizmi engineering journal ,vol.1, no. 1,pp 61-72 (2005) ٦٥ produces an anterior sacral tiltxxii, which causes it to sink forward and downward. this potential motion puts the posterior sacroiliac ligaments (in addition to the sacrotuberous and sacrospinous) on stretch, which is an automatic locking devicexxii, xxiii. in the following discussion of the finite element analysis model, we will refer to the values obtained in assuming a 70kg person. the high stress found in the ischial tuberosity emphasizes the role of the sacrotuberous ligament in weight transmission as has been suggested above. the minor role on the sacrospinous ligament is indicated by the low stress values; these values are attributed to its role in stability rather than weight transmission. regions of the hip bone that do not lie in the line of weight transmission showed lower stress values; this is clear at the iliac crest, iliac fossa, body and ramus of the ischium. the intact acetabulum is a horseshoe form that wraps around the superior, anterior, and posterior aspects of the slightly eccentric femoral head. in the lightly loaded state for the 70 kg, the dome of the acetabulum is relatively unloaded, and the stress is transferred from the femoral head to the acetabulum through the anterior and posterior extensions of the horseshoe as indicated in (fig 7), and it is represented by the red color (arrows). as the load is progressively applied, for the 90kg and the 110kg since the acetabulum is not in continuity inferiorly, the stresses will be distributed superiorly and the anterior and posterior sides of the horseshoe are free to expand so that a more congruous seating of the femoral head is allowed. this phenomenon of deformation under load leads to increasing congruity with progressive loading. table-1: descriptive statistics of the area (cm2) of the articulating surfaces of the hip bone lunate surface symphysis pubis auricular surface mean 24.63 44.58 14.39 standard error 0.541 0.185 0.347 median 24.46 43.7.4 14.43 mode 24.46 43.74 ---- minimum 17.62 20.17 10.71 maximum 30.26 73.6 18.74 sample size 35 35 35 sadiq jaffar abass/al-khwarizmi engineering journal ,vol.1, no. 1,pp 61-72 (2005) ٦٦ table 2: percentages of the distribution of von mises stress for 70 kg body weight region von mises stress percentages for (70kg) sacroiliac joint 24.6% sacrospinous ligament 1.5% sacrotuberous ligament 40.3% ac et ab ul um anterior 11.2% posterior 15.9% superior 5.4% symphysis pubis 0.89% fig.1 digrammaic representation of hip bone mechanics fig.2 example of wax pieces that fitted the articular surface of the (a) acetabulum, (b) auricular surface, & (c) symphysis pubis a c b sadiq jaffar abass/al-khwarizmi engineering journal ,vol.1, no. 1,pp 61-72 (2005) ٦٧ fig.3 computer screen after the model have been meshed fig.4 accessory sacroiliac joint (arrow) sadiq jaffar abass/al-khwarizmi engineering journal ,vol.1, no. 1,pp 61-72 (2005) ٦٨ fig..5 : frequency distribution of the surface areas of the lunate and auricular surfaces 0 2 4 6 8 10 12 14 10 12 15 17 20 22 25 27 30 32 35 area (cm2 ) fr eq ue nc y auricular surface lunate surface fig. 6 : regression of the auricular versus the lunate surface areas y = 0.8828 x + 1193 0 5 10 15 20 25 30 35 0 2 4 6 8 10 12 14 16 18 20 auricular surface ( cm2 ) lu na te s ur fa ce (c m 2 ) sadiq jaffar abass/al-khwarizmi engineering journal ,vol.1, no. 1,pp 61-72 (2005) ٦٩ fig 7: von mises stress distribution on the lateral surface of the hip bone in a 70 kg body by using asnsys program for fea. fig 8: von mises stress distribution on the medial surface of the hip bone for a 110 kg body by using ansys program for fea red red sadiq jaffar abass/al-khwarizmi engineering journal ,vol.1, no. 1,pp 61-72 (2005) ٧٠ conclusion: statistical analysis of articulating surface areas indicated that both the lunate and auricular surfaces are involved in force transmission through the hip bone. the symphysis pubis is part of the anterior buttressing arch of the articulating pelvis. area differences indicated that only 49% of the load reaching the hip bone is being transmitted through the sacroiliac joint. this emphasizes the role of the ligaments which should transmit most of the remaining load. the high stresses at the ischial tuberosity can be attributed to the important role of the sacrotuberous ligament. the sacroiliac joint and acetabular stress values are inversely comparable to their areas references: 1. kummer,-b., the clinical relevance of biomechanical analysis of the hip area. z-orthop-ihre-grenzgeb, 1991, 129:285-294. 2. valstar er, botha cp, van der glas m, rozing pm, van der helm fct, post fh, & vossepoel am: towards computer assisted surgery in shoulder joint replacement. journal of photogrammetry & remote sensing. 2002, 56:326-337 3. lotz jc, cheal ej & hayes wc: stress distributions within the proximal femur during gait and falls: implications for osteoporotic fracture. osteoporos-int., 1995, 5:252-261. 4. będziński r & tyndyk m: a study of the strain and the stress distribution in the pelvis bone under different load conditions, 12th conference of the european society of biomechanics, dublin, 2000. 5. bannister lh, berry mm, collins p, dyson m, dussek je, & ferguson mwj: gray’s anatomy. 38th ed. cdrom version. pelvic mechanism. record 6019. folio bound views. harcourt brace & co. usa 6. bogduk n, pearcy m, & hadfield g: anatomy and biomechanics of the psoas major. clinical biomechanics. 1992, 7:109-119. 7. adams ma & hutton wc: the mechanical function of the lumbar apophyseal joints. spine. 1983, 8: 327 8. carter dr & hayes wc: the compressive behaviour of bone as a two-phase porous structure. journal of bone joint surgery. 1976, 59:954-962. 9. zannoni c, testi d & cappello a.: spiral ct scanning plan to generate accurate fe models of the human femur. journal of the international federation for medical & biological engineering 1999; 37( s2):1030-1031. 10. centre of mechanical technology and automation. biomechanics. url:http://www.mec.ua.pt/tema/unit/res lines18.html. accessed: march, 2005 11. afoke nyp, byers pd & hutton wc: contact pressures in the human hip joint. j bone joint surg. 1987, 69b:536-541 12. niebur gl., et al.: high-resolution finite element models with tissue strength asymmetry accurately predict failure of trabecular bone. journal of biomechanics. 2000. 33:1575-1583. 13. huiskes r, elangovan pt, banens jpa & slooff tj: finite element http://www.mec.ua.pt/tema/unit/res sadiq jaffar abass/al-khwarizmi engineering journal ,vol.1, no. 1,pp 61-72 (2005) ٧١ computer methods for design and fixation problems of orthopaedic implants, biomechanics vi-b, asmussen e and jorgensen k, editors. university park press, baltimore. 1978, pp229-238 14. levin sm: the importance of soft tissue for structural support of the body, prolotherapy in the lumbar spine and pelvis. spine.1995, 9:357. 15. buchler p, ramaniraka na, rakotomanana lr, iannotti jp & farron a: a finite element model of the shoulder: application to the comparison of normal and osteoarthritic joints. clinical biomechanics. 2002, 17:630-639 16. rakesh s, zachariah sg, & sanders je: processing computer tomography bone data for prosthetic finite element modeling : a technical note. j. rehab. res. dev. 2002, 39:609-614 17. zivkovic i, amirouche f & gonzalez m: university of illinois at chicago. biomechanics research laboratory. hip research. url: http://www.uic.edu/labs/brl/hip1.htm. accessed: march 2005 18. pal gp & routal rv: transmission of weight through the lower thoracic and lumbar regions of the vertebral column in man. j. anat. 1987, 152:93-105. 19. oomori h, imura s, gesso h, tanaka y, ichihashi k, takedani h, okumura y & boh a: biomechanical study of femoral stem load transfer in cementless total hip arthroplasty using a nonlinear two-dimensional finite element method. in: imura s, akamatsu n, azuma h, sawai k and tanaka s. (eds.): hip biomechanics. springer-verlag. tokyo. 1993, pp239-253. 20. carter dr: the cemented acetabular component: biomechanics and skeletal adaptation. non-cemented total hip arthroplasty. raven press. new york. 1988, pp257-276. 21. davis pr: human lower lumbar vertebrae: some mechanical and osteological consideration. j. anat. 1961, 95:337-344 22. porterfield ja & derosa c: the sacroiliac joint. in: ja gould (ed.): orthopaedic and sports physical therapy, 2nd ed. mosby. st louis. 1990. 23. miller jaa, schultz ab & andersson gbj:load-displacement behavior of sacroiliac joints. j orthop res. 1987, 5:92-101 http://www.uic.edu/labs/brl/hip1.htm sadiq jaffar abass/al-khwarizmi engineering journal ,vol.1, no. 1,pp 61-72 (2005) ٧٢ ظم الحوضتحليل االجهادات في ع صادق جعفر عباس. د أكرم عبود جعفر . د هوما محمد عبد اهللا جامعة النهرين :الخالصة ان التعقيد، الشـكل الخـارجي، صـفات . ألطراف السفلىلوزن االيلعب عظم الحوض دورا كبيرا في نقل .البايوميكانيكيه العظم، والقوى المسلطة عليه تجعل منه موضوعاً مفتوحا لغرض الدراسة والتحليالت أضـافة إلـى . لسطح االذيني، السطح الهاللي، واالرتفاق العانيامع قياس مساحات ةتتعامل هذه الدراس الثالثية األبعاد لعظم الحوض لغـرض دراسـة القيمـة، اتجـاه توزيـع القـوى، المحددةتحليل العناصر .وانتشاراالجهادات تحت الظروف الفسلجيه للجسم حـوض ةعظم) ٣٥(في السطح الهاللي، واالرتفاق العاني ،ات السطحية للسطح االذينيتم قياس المساح لغرض تحليـل العناصـر ansysمجسم صلب لعظم الحوض إلى برنامج تم تحويلكما . لإلنسان البالغ .تحت تأثير القوى المختلفة المحددة ٢.٠٥±١٤.٣٩(العـاني للسـطح االذينـي، السـطح الهاللـي، واالرتفـاق ةكانت المساحات السـطحي بين السـطح ةفي العالق ةايجابي ةزيادوجود ظهر . على التوالي ٢سم) ٣.٢± ٢٤.٦٣و , ١.٠٩±٤.٤٦, عندما تـم . اال ان مثل هذه العالقة لم تظهر بين السطح الهاللي واالرتفاق العاني، الهاللي والسطح االذيني طريقة فون ميسـز للنموذج باستخدام المحددةر كيلوغرام لتحليل العناص٧٠لوزن ةتسليط القوى بالنسب ـ (تتوزع بشكل رئيسي في تجويف الحـق أن االجهاداتب ظهر ، ٥.٤%، العليـا %11.2ةالجهـه االمامي أظهـرت النتـائج أن ). ٤٠.٣%(الحدوبة الوركيـة وا، ) ٢٤.٦%(، السطح االذيني )١٥.٩ %ةوالخلفي اما فيما يتعلق باالجهاد الرئيسـي فقـد .تتناسب تناسبا طرديا مع األوزان المسلطة لوزن اعلىاالجهادات لتجويف الحق وكذلك في المفصل ةوالخلفي ةاالمامي ةأظهرت النتائج أن نقاط الفشل سوف تظهر في الجه .الحرقفي–العجزي لسطح االذيني يساهمان في أن سطح الهاللي وا ةللمساحات السطحية التمفصلي ةاظهرت التحليالت االحصائي . لحزام الحـوض ةنقل القوى خالل عظم الحوض أما االرتفاق العاني فهو جزء رئيسي في الدعامة أالمامي من القوى التي تصل عظم الحوض تنتقل من خالل % ٤٩ألى أن الفرق في المساحات يدل على ان ةأضاف ان . بير في نقل الجـزء االكبـر ممـا تبقـى دور ك ةالحرقفي وهذا يدل على أن لالربط -المفصل العجزي االجهادات الكبيرة التى ظهرت في االحدوبة الوركية يمكن ان تُعزى الى الدور الكبير الذي يقوم به الربـاط الحرقفي و تجويف الحـق تتناسـب تناسـبا -االجهادات في المفصل العجزي ةان قيم. العجزي االحدوبي . عكسيا مع المساحه sadiq jaffar abass/al-khwarizmi engineering journal ,vol.1, no. 1,pp 61-72 (2005) ٧٣ نصير ومصطفى al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 2637 (2013) enhancement of a power system transient stability using static synchronous series compensator sssc naseer m. yasin* mustafa m. al-eedany** *,**department of electrical engineering / college of engineering / university of basrah *emial: naseeryasin@yahoo.com **emial: maleedany2006@yahoo.com (received 20 march 2013; accepted 3 september 2013) abstract static synchronous series compensator (sssc) is a well known device for effectively regulating the active power flow in a power system. in this paper, the sssc linearized power flow equations are incorporated into newton-raphson algorithm in a matlab written program to investigate the control of active poweer flow and the transient stability of a five bus and a thirty bus ieee test systems, during abnormal conduction (three phase fault near buses). a comparison of the results obtained for the base case without sssc and with it to investigate the effectiveness of the device on both of the active power flow and the transient stability. keywords: load flow analysis, newton-raphson, sssc. 1. introduction rapid development of power systems especially with the increased use of transmission facilities has necessitated new ways of maximizing power transfer in existing transmission facilities while maintaining the same level of stability [1]. monitoring the stability status of a power system in real time has been recognized as a task of primary importance in preventing blackouts. in case of a disturbance leading to transient instability, fast recognition of the potentially dangerous conditions is very crucial for allowing sufficient time to take emergency control actions. several attempts to develop an effective real-time transient stability indicator have been reported in the literature [2–4]. the transient stability of power systems is associated with the ability of the generators to remain in synchronism after a severe disturbance [5]. it depends upon the severity of the contingency and the initial operating state of the power systems. here the term contingency, also called disturbance or fault, indicates an event like the three-phase short circuit in the grid that will cause large changes in power system [6]. the operating power system will first encounter the hurdle of transient stability before apparatuses thermal limits [7]. when a contingency occures in the electrical network, the power system is likely to lose stability, or may be even worse to trigger large scale blackouts [8]. in order to avoid catastrophic outages, power utilities resort to various planning, protection and control schemes. preventive control is summoned up when the power system is still in normal status. it encompasses many types of control actions, including generation rescheduling, load curtailment and network switching reactive compensation [9,10]. those preventive control actions reallocate power system operating state so that it can guarantee satisfactory behavior after a contingency occurred in the grid. the real time transient stability assessment (tsa) is important to the power system security and efficient operation. otherwise essential control actions could be delayed, which in turn could trigger a large scale blackout. further, real time tsa will avoid any unnecessary control mailto:naseeryasin@yahoo.com mailto:maleedany2006@yahoo.com naseer m. yasin al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 2637 (2013) 27 commands to ensure the minimum impact on the grid. the conventional transient stability measure of a system’s robustness to withstand a large disturbance is its corresponding critical clearing time (cct) which is the maximum time duration for which the disturbance may act without the system losing its capability to recover a steadystate (i.e., stable) operation [11]. in the late 1980s, the electric power research institute (epri) formulated the vision of the flexible ac transmission systems (facts) in which various power-electronics based controllers regulate power flow and transmission voltage and mitigate dynamic disturbances. fast development of power electronic technology has made facts promising solution of the future power system. facts controllers such as static synchronous compensator (statcom), static var compensator (svc), thyristor controlled series compensator (tcsc), static synchronous series compensator (sssc) and unified power flow controller (upfc) are able to change the network parameters in a fast and effective way in order to achieve better system performance [12-14]. these controllers are used for enhancing dynamic performance of power systems in terms of voltage/angle stability while improving the power transfer capability and voltage profile in steady-state conditions [15-17]. in [18], the modeling of facts devices for power flow studies and the role of that modeling in the study of facts devices for power flow control are discussed. three essential generic models of facts devices are presented and the combination of those devices into load flow analysis, studies relating to wheeling, and interchange power flow control is explained. the determination of the voltage magnitude and phase angle of the facts bus is provided by solving two simultaneous nonlinear equations. these equations are solved with a separate newtonraphson approach within each iteration of the large load flow analysis. in [19], various control methods for damping undesirable inter-area oscillations by power system stabilizers (pss), svcs and statcoms are discussed. it is observed that the damping introduced by the svc and statcom controllers with only voltage control was lower than that provided by the psss and the statcom provides better damping than the svc as this controller is able to transiently exchange active power with the system. in [20], the main characteristics of controllable reactive series elements (crse), which sometimes called controllable series compensation (csc) and a static synchronous series compensator for power system analysis and control are shown. modeling of crse, containing a simple representation of the transmission system, have been developed. according to theses concepts, the crse effect on a longitudinal transmission system was analyzed. the theory of physics and the basic difference shown by a csc and an sssc related load flow control are explained. due to conceptual principles, by the of ability of load flow control, sssc is considered as more promising than csc at low power angles. therefore, sssc is more suitable in cases where power flow requires to be controlled in short lines or under light-load conditions. 2. static synchronous series compensator (sssc) the sssc is a member of facts family which is connected in series with a power system. it consists of a solid state voltage source converter which generates a controllable alternating voltage at the fundamental frequency. when the injected voltage is kept in quadrature with the line current, it can emulate as inductive or capacitive reactance so as to influence the power flow through the transmission line [21]. while the primary purpose of a sssc is to control power flow in steady state, it can also improve transient stability of a power system [22]. 3. modeling of sssc the sssc is one of the most recent facts devices for power transmission series compensation. it can be considered as a synchronous voltage source as it can inject an almost sinusoidal voltage of variable and controllable amplitude and phase angle, in series with a transmission line. the injected voltage is almost in quadrature with the line current. a small part of the injected voltage that is in phase with the line current provides the losses in the inverter. most of the injected voltage, which is in quadrature with the line current, provides the effect of inserting an inductive or capacitive reactance in series with the transmission line. the variable reactance influences the electric power flow in the transmission line. the basic configuration of an sssc is shown in figure (1). naseer m. yasin al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 2637 (2013) 28 fig. 1.the operating principles of sssc. for the purpose of steady-state operation, the sssc injects voltage in quadrature with one of the line end voltages in order to regulate active power flow. however, the sssc is a far more versatile controller as it does not draw reactive power from the ac system, it has its own reactive power provisions in the form of a dc capacitor. this characteristic makes the sssc capable of regulating not only active but also reactive power flow or nodal voltage magnitude [23]. a schematic representation of the equivalent circuit of an sssc is shown in figure (2). fig. 2. simplified diagram of a sssc. the series voltage source of the sssc may be represented by: = ( + . ) …(1) the magnitude and phase angle of the sssc model are adjusted by using any suitable iterative algorithm to satisfy a specified active and reactive power flow across the sssc. maximum and minimum limits will exist for the voltage magnitude vse, which is a function of the sssc capacitor rating, the voltage phase angle δse can take any value between 0 and 2 radians. based on the equivalent circuit shown in figure (2), the following transfer admittance equation can be written [23]. = − − − …(2) the power equations at bus i are: = sin ( − )+ sin( − ) …(3) = − − cos − cos( − ) …(4) where: = = − for the powers at bus j, exchange the subscripts i and j. in newton–raphson solutions these equations are linearized with respect to the series injected voltage. for the condition shown in figure (2), where the series injected voltage regulates the amount of active power flowing from bus i to bus j at a value pspecified, the set of linearized power flow equations are: ∆ ∆ ∆ ∆ ∆ − = / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / ∆ ∆ ∆ ∆ ∆ ∆ …(5) naseer m. yasin al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 2637 (2013) 29 where the elements of the added row and column are = − …(6) = sin ( − ) + sin ( − ) …(7) = sin ( − ) + sin ( − )…(8) where is the power for the series converter (sssc) 4. prgram stracture after reading the line and bus data for the power system, the matlab written program starts by forming the bus admittance, then using newton raphson method, it calculates the active and reactive power of the slack bus, the voltages and angles of each load bus. then the stability program calculates the new bus admittance during fault, and the post fault admittance. the solution of the diferrential power equations is solved using runge-kutta method to simulate the variation of power angle with time. figure (3) shows the flow chart of the program. fig. 3.the flow chart of the transient stability program. 5. simulation and results the ieee 5-bus system, figure (4), is used to test the effectiveness of connecting the sssc device between bus3 and bus4, the data of which can be found in [23]. using newton-raphson method, the power flow results of the system without the sssc connected are shown in table (1). fig. 4. single line diagram of ieee-5 bus network with sssc. 3 sssc 1 5 4 3 2 star input line data and bus data form admittance matrix assume i 0δ for i=2,3,4…n iv 0 for i=2,3,….,m for pq set iteration count k=0 find i kp and i kq for find imax i kp∆ , imax i kq∆ is imax ε≤∆ i kp imax ε≤∆ i kq output load flow information input fault location and simulation duration solve diferrential equations by runge-kutta k= k+1 stop plot power angle v. time no yes naseer m. yasin al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 2637 (2013) 30 table 1, power flow results of 5-bus system without sssc connected line flow and losses --line-power at bus & line flow --line loss- from to p (mw) q (mvar) s (mva) p (mw) q (mvar) 1 1 131.122 90.816 159.501 1 2 89.331 73.995 115.997 2.486 1.087 1 3 41.791 16.820 45.049 1.518 -0.692 2 2 20.000 -71.593 74.334 2 1 -86.846 -72.908 113.392 2.486 1.087 2 3 24.473 -2.518 24.602 0.360 -2.871 2 4 27.713 -1.724 27.767 0.461 -2.554 2 5 54.660 5.558 54.942 1.215 0.729 3 3 -45.000 -15.000 47.434 3 1 -40.273 -17.513 43.916 1.518 -0.692 3 2 -24.113 -0.352 24.116 0.360 -2.871 3 4 19.386 2.865 19.597 0.040 -1.823 4 4 -40.000 -5.000 40.311 4 2 -27.252 -0.831 27.265 0.461 -2.554 4 3 -19.346 -4.688 19.906 0.040 -1.823 4 5 6.598 0.518 6.619 0.043 -4.652 5 5 -60.000 -10.000 60.828 5 2 -53.445 -4.829 53.663 1.215 0.729 5 4 -6.555 -5.171 8.349 0.043 -4.652 total loss 6.122 -10.777 it is required to regulate the power flow from bus3 to bus4 to a value of 21mw instead of 19.386mw. this is done by creating a virtual bus between bus3 and bus4 namely bus6, by adding ( = 1 , = 0) to bus data in the beginning of the iterative process of load flow. then connecting the sssc between bus3 and bus6 (setting the value of xse=0.0216pu in the line data). the new system manages to achieve this task and maintains active power flow at the specified value in six iterations with a final value for the angle δse of -100.888˚, the load flow results and the power flow with the sssc connected is shown table (2 and 3) respectively. naseer m. yasin al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 2637 (2013) 31 table 2, load flow results of 5 bus system with sssc connected. power flow solution by newton-raphson method maximum power mismatch = 8.48344e-015 no. of iterations = 6 bus voltage angle ------load--------generation-- no. mag. degree p(mw) q(mvar) p(mw) q(mvar) 1 1.060 0.000 0.000 0.000 131.127 90.937 2 1.000 -2.038 20.000 10.000 40.000 -61.801 3 0.987 -4.727 45.000 15.000 0.000 0.000 4 0.984 -4.811 40.000 5.000 0.000 0.000 5 0.972 -5.701 60.000 10.000 0.000 0.000 6 0.988 -4.461 0.000 0.000 0.000 0.000 total 165.00 40.000 171.127 29.136 table 3, power flow results of 5-bus system with sssc connected. line flow and losses --line-power at bus & line flow --line loss- from to p (mw) q (mvar) s (mva) p (mw) q (mvar) 1 1 131.127 90.937 159.574 1 2 88.680 74.187 115.619 2.471 1.041 1 3 42.447 16.750 45.632 1.555 -0.579 2 2 20.000 -71.801 74.534 2 1 -86.210 -73.146 113.059 2.471 1.041 2 3 25.497 -2.694 25.639 0.390 -2.777 2 4 26.606 -1.567 26.652 0.425 -2.664 2 5 54.106 5.606 54.396 1.191 0.657 3 3 -45.000 -15.000 47.434 3 1 -40.892 -17.329 44.412 1.555 -0.579 3 2 -25.107 -0.084 25.107 0.390 -2.777 3 6 20.999 2.412 21.137 0.000 -0.099 4 4 -40.000 -5.000 40.311 4 2 -26.181 -1.097 26.204 0.425 -2.664 4 6 -20.952 -4.316 21.392 0.046 -1.805 4 5 7.133 0.413 7.145 0.049 -4.638 5 5 -60.000 -10.000 60.828 5 2 -52.915 -4.949 53.146 1.191 0.657 5 4 -7.085 -5.051 8.701 0.049 -4.638 6 6 0.000 0.000 0.000 6 3 -20.999 -2.512 21.149 0.000 -0.099 6 4 20.999 2.511 21.148 0.046 -1.805 total loss 6.127 -10.864 naseer m. yasin al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 2637 (2013) 32 to show that the new system's transient stability has been enhanced, a matlab program which uses runge-kutta method to solve the diferrential equations of the power system is written a three phase fault is created at the transmission line (1-2) near bus1, and cleared by the removal of t.l. (1-2) for both the base case and the new system. for the base case where no sssc is connected the power angle curve is shown in figure (5) for a critical clearing time cct=0.318sec. fig. 5 . fault cleared at cct=0.318sec without sssc. figure (5) shown is a plot of the power angle difference between generator at bus2 (south) and the slack at bus1 (north) namely δ21. since δ21=2.038° at steady state operation, the increase is in the negative side. as can be seen the generator at south is oscillating with the generator at north, which means that with the inclusion of damping the oscillations would subside, and therefore the system is considered to be stable. the curve shows that the system recovers its stability, however, when the cct is increased to a value of 0.319 sec. the system looses its stability as shown in figure (6), where δ21 decreases to infinity. fig. 6. fault cleared at cct=0.319sec without sssc. when the sssc was included and the system tested for an even more increased critical clearing time cct=0.320 sec, it retains its stability as shown figure (7). fig. 7. fault cleared at cct=0.320 sec with sssc included. the other test system is the ieee 30-bus system, the single line diagram of which is shown in figure (8) is implemented to evaluate the effectiveness of the sssc model. the data of which can be found in [24]. 0 0.5 1 1.5 2 2.5 3 3.5 4 -150 -100 -50 0 50 100 t, sec d el ta , d eg re e 0 0.5 1 1.5 2 2.5 3 3.5 4 -7000 -6000 -5000 -4000 -3000 -2000 -1000 0 t, sec d el ta , d eg re e 0 0.5 1 1.5 2 2.5 3 3.5 4 -150 -100 -50 0 50 100 t, sec d el ta , d eg re e naseer m. yasin al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 2637 (2013) 33 fig. 6. fault cleared at cct=0.319sec without sssc. when the sssc was included and the system tested for an even more increased critical clearing time cct=0.320 sec, it retains its stability as shown figure (7). fig. 7. fault cleared at cct=0.320 sec with sssc included. the other test system is the ieee 30-bus system, the single line diagram of which is shown in figure (8) is implemented to evaluate the effectiveness of the sssc model. the data of which can be found in [24]. fig. 8. single line diagram of ieee-30 bus system. using newton-raphson method, the power flow results of the system without the sssc are shown in table (4) for bus 3 only. the sssc is connected between bus3 and bus4 and is used to regulate the active power flowing from bus3 towards bus4 to a value of 90mw instead of 78.012mw, this is done by creating a new bus31 between bus3 and bus4 to connect the sssc between bus3 and bus31 (setting the value of xse=-0.0098pu) so that the active power flowing towards bus4 is the specified regulated power i.e. 90mw as shown in table (5). the model manages to maintain the specified active power flowing towards bus4 with a final value for vse=0.001pu and an angle δ21 =-95.2825˚ 0 0.5 1 1.5 2 2.5 3 3.5 4 -7000 -6000 -5000 -4000 -3000 -2000 -1000 0 t, sec d el ta , d eg re e 0 0.5 1 1.5 2 2.5 3 3.5 4 -150 -100 -50 0 50 100 t, sec d el ta , d eg re e naseer m. yasin al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 2637 (2013) 34 table 4, power flow results of 30-bus system without sssc connected. line flow and losses --line-power at bus & line flow --line loss- from to p (mw) q (mvar) s (mva) p (mw) q (mvar) 3 3 -2.400 -1.200 2.683 3 1 -80.412 1.958 80.436 2.808 7.085 3 4 78.012 -3.158 78.076 0.771 1.344 table 5, power flow results of 30-bus system with sssc connected. line flow and losses --line-power at bus & line flow --line loss- from to p (mw) q (mvar) s (mva) p (mw) q (mvar) 31 31 0.000 0.000 0.000 31 3 -80.238 2.103 80.266 0.000 -0.601 31 4 90.000 -1.847 90.019 1.017 2.047 to test whether the new system has acquired a new margin of transient stability, a three phase fault is created near bus1 at transmission line (13), and removed by removing the faulty transmission line (1-3) for both the base case and the new system with the sssc. for the model without the sssc connected, when the faulty line was cleared after a critical clearing time cct of 0.190 sec, the swing curve shows that the power angle returns after a maximum swing indicating that with the inclusion of system damping, the oscillations will subside and a new operating angle is attained. hence, the system is found to be stable for this fault clearing time, as shown in figure (9). fig. 9. fault cleared at cct=0.190 sec without sssc however, when the cct was increased to a value of 0.191sec, the difference in rotor angle between machine2 and machine1 is continuously increasing, and therefore the system is considered to be unstable as shown in figure (10). 0 0.5 1 1.5 2 2.5 3 3.5 4 -160 -140 -120 -100 -80 -60 -40 -20 0 20 40 t, sec d el ta , d eg re e naseer m. yasin al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 2637 (2013) 35 fig. 10. fault cleared at cct=0.191sec without sssc. when the sssc was included in the model and following the same procedure for the fault at bus1 and removed by the removal of the same transmission line (1-3) after an even more increased cct of 0.211sec, the system retains its stability as shown in figure (11). fig. 11. fault cleared at cct=0.211sec with sssc included. 6. conclusions in this paper the model for power flow and transient stability for an ieee five and thirty bus test systems with the sssc included was developed and the results for specifying the active power flow in a certain branch of the power system were verified, it was found that the active power in branch (3-4) could be increased by nearly 1.6mw for the ieee-5 bus test system and nearly 12mw for the ieee-30 bus test system. the transient stability was also tested and the results show that the stability margin was increased by the inclusion of the sssc device for the ieee-5 bus by 0.2% and the ieee-30 bus by 2.1%. 7. references [1] m. o. hassen, s.j.cheng and z. a. zakaria "steady state modelling of svc and tcsc for power flow analysis" proc. of the inter. multiconferance of engineering and computer scientists vol.2, 2009. [2] f. f. song, t. s. bi, and q. x. yang, “study on wide area measurement system based transient stability control for power systems,” in proc. ipec power engineering conf., vol. 2, 2005, pp. 757–760. [3] a. g. phadke, “synchronized phasor measurements in power systems,” ieee computer appl. power, vol. 6, no. 2, apr. 1993, pp. 10–15. [4] h. dongchen and v. venkatasubramanian, “new wide-area algorithms for detection and mitigation of angle instability using synchrophasors,” in proc. power eng. soc. general meeting, june 2007, pp. 1–8. [5] p. kundur, 1. paserba and v. ajjarapu , " definition and classification of power system stability ieee/cigre joint task force on stability terms and definitions," ieee trans. on power systems, vol. 19, aug. 2004, pp. 1387-1401. [6] m. pavella, d. ernst and d. ruiz-vega, “transient stability of power systems,” kluwer academic publishers, 2000,pp.6 [7] a. olwegard, k. walve, g. waglund, h. frank and s. toresng, “improvement of transimission capacity by thyristor controlled reactive power,” ieee trans. on power apparatus and systems, vol. 100, no. 8, 1981, pp. 3930-3939. [8] p. poubeik, p. s. kundur, and c. w. taylor, “the anatomy of a power grid blackout root causes and dynamics of recent major blackouts ,” ieee power & energy magazine, vol. 4, sep/oct 2006, pp. 22-29. [9] l. wehenkel and m. pavella, “preventive vs. emergency control of power systems,” ieee power energy society power systems conf. & exposition, vol. 3, 2004, pp. 1665 1670. [10] d. ernst, l. wehenkel and m. pavella, “what is the likely future of real-time transient stability,” ieee power energy society power systems conf. and exposition, 2009, pp. 1 3 . 0 0.5 1 1.5 2 2.5 3 3.5 4 -15000 -10000 -5000 0 t, sec d el ta , d eg re e 0 0.5 1 1.5 2 2.5 3 3.5 4 -150 -100 -50 0 50 t, sec d el ta , d eg re e naseer m. yasin al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 2637 (2013) 36 [11] a. hoballah, and istván erlich," transient stability assessment using ann considering power system topology changes," ieee 15th international conference on intelligent system applications to power systems, 2009, pp. 1. [12] n.g. hingorani, l. gyugyi, “understanding facts: concepts and technology of flexible ac transmission systems”, wileyieee press, new york, 2000. [13] a. edris, “facts technology development: an update,” ieee eng. review, vol. 20 2000, pp.4-9. [14] r.mohan marthur and rajiv k.varma “thyristor based-facts controllers for electrical transmission systems“,ieee computer society press, 2002. [15] l. kirschner, d. retzmann. and g. thumm "benefits of facts for power system enhancement,” transmission and distribution conference and exhibition asia and pacific, 2005 ieee/pes, pp.1 – 7. [16] y. ou; c. singh, "improvement of total transfer capability using tcsc and svc,” power engineering society summer meeting, 2001. ieee , vol. 2, july 2001, pp. 944-948. [17] x. yu, c. singh, s. jakovljevic, d. ristanovic and g. huang, ” total transfer capability considering facts and security constraints,” transmission and distribution conference and exposition, vol. 1, sept. 2003, pp.73 78. [18] c. w. taylor, “improving grid behavior”, ieee spectrum, vol. 36, no. 6, pp. 40-45, june 1999. [19] t. luor, y. hsu, t. guo, j. lin, and c. huang, “application of thyristor-controlled series compensators to enhance oscillatory stability and transmission capability of longitudinal power system”, ieee transactions on power system, vol. 14, no. 1, pp. 179-185, feb. 1999. [20] l. gyugyi,"solid-state synchronous voltage sources for dynamic compensation and real-time control of ac transmission lines", emerging practices in technology, ieee standards press, 1993. [21] l. gyugyi, “dynamic compensation of ac transmission line by solid state synchronous voltage sources,” ieee, transactions on power delivery, ieee transactions on power delivery, vol. 9, 1994, pp.904-911. [22] d. murali, dr. m. rajaram, and n. rekai, ."comparison of facts devices for power system stability enhancement" international journal of computer applications, vol. 8, no.4, october 2010, pp. 30-34. [23] e. asha, c. r. fuerte esquival, h. ambriz, and c. a. camacho, "modeling and simulation in power networks" john wiley & sons ltd, the atrium, southern gate, chichester, 2004. [24] h. saadat "power system analysis", mcgraw-hill series in electrical computer engineering, 1999. )2013( 2637 ، صفحة3، العدد9مجلة الخوارزمي الھندسیة المجلد نصیر مجید یاسین 37 تعزیز االستقراریة العابرة لنظام القدرة بأستخدام المعوض التناسقي المتوالي ** مصطفى محمد ابراھیم *نصیر مجید یاسین جامعة البصرة/ كلیة الھندسة / دسة الكھربائیة قسم الھن**،* naseeryasin@yahoo.com : االلكتروني البرید* maleedany2006@yahoo.com: البرید االلكتروني** الخالصة بطریقة نیوتن رابسون في في ھذا البحث تم استخدام معادالت سریان القدرة . یعرف المعوض التزامني المتوالي كجھاز لتنظیم سریان القدرة الفعالة خطأ ثالثي في برنامج مكتوب بلغة ماتالب لبحث سریان القدرة الفعالة واالستقراریة العابرة لمنظومة ذات خمسة الواح واخرى ذات ثالثین لوح عند حدوث م وجوده لدراسة تأثیره على سریان القدرة الفعالة تم أجراء مقارنة بین نتائج النظام في حالة وجود المعوض التزامني المتوالي وفي حالة عد. احد االلواح .واالستقراریة العابرة mailto:naseeryasin@yahoo.com mailto:maleedany2006@yahoo.com عباس حميد و د.عماد وشيماء al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 5768 (2013) efficiency prediction and performance characterization of photovoltaic solar panel at baghdad climate conditions abbas hamid sulaymon emad talib hahsim shaymaa alaulddin mahdi department of energy engineering/ college of engineering / university of baghdad (received 17 february 2013; accepted 28 may 2013) abstract the performance of a solar cell under sun radiation is necessary to describe the electrical parameters of the cell. the prova 200 solar panel analyzer is used for the professional testing of four solar cells at baghdad climate conditions. voltage -current characteristics of different area solar cells operated under solar irradiation for testing their quality and determining the optimal operational parameters for maximum electrical output were obtained. a correlation is developed between solar cell efficiency η and the corresponding solar cell parameters; solar irradiance g, maximum power pmax, and production date p. the average absolute error of the proposed correlation is 5.5% for 40 data points. the results also show that the new solar panels have the highest efficiency compared with the older ones. keywords: solar cell, photovoltaic performance, fill factor, efficiency. 1. introduction the production of photovoltaic electricity has known in recent years an increasing of interest by a production exceeding 1800 mw throughout the world. this increase was accompanied by a revitalization of researches considered for the optimization of the energy given by solar cells. nowadays, the world's energy needs are growing steadily. however, the conventional sources of energy are limited. solar energy such as photovoltaic energy (pv) is the most available energy source which is capable to provide this world’s energy needs. the conversion of sunlight into electricity using solar cells system is worthwhile way of producing this alternative energy. the history of photovoltaic energy started in 1839 when alexandre-edmond becquerel discovered the photovoltaic effect [1]. photovoltaic system uses various materials and technologies such as crystalline silicon (c-si), cadmium telluride (cdte), gallium arsenide (gaas), chalcopyrite films of copper-indiumselenide (cuinse2), etc [1]. in solar technology, the main challenge of researchers is to improve solar cells efficiency. due to this challenge, several investigations have been developed to characterize the solar cells by the determining their parameters [2],[3]. indeed, it is important to know these parameters for estimating the degree of perfection and quality of silicon solar cells. solar cell efficiency is an important input parameter in pv-powered product design. often, only limited space is available for the solar cells to be integrated. cell efficiency can even become a criterion of principal system feasibility. as a basic parameter, cell efficiency serves as an input in calculating the optimal system configuration, e.g., as a cost related trade-off between the storage unit and its lifetime, pv size and its efficiency, although these calculations are well known for autonomous pv systems, e.g. [4] and finally the demand side with correlated consumption profiles. the objectives of the present paper are to find a functional relationship between solar cell efficiency with the solar cell parameters and characterize the performance of different types of solar cells. abbas hamid sulaymon al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 57-68 (2013) 58 2. output characteristics of solar cells the output characteristics of solar cells are expressed in the form of an i v curve. a typical i v curve and the test circuit used are shown in fig.1 (a,b) [5]. the i-v curve is produced by varying rl (load resistance) from zero to infinity and measuring the current and voltage along the way. the point at which the i-v curve and resistance (rl) intersect is the operating point of the solar cell. the current and voltage at this point are ip and vp, respectively. the largest operating point in the square area is the maximum output of the solar cell as it's demonstrated in fig.2. 3. experimental measurements the prova 200 solar panel analyzer (fig.3) is used for the professional testing and maintenance of solar panels and modules. table 1 provides the general specification of prova 200. in addition to maintenance and installation of solar panels, the prova 200 solar panel analyzer can be used in the manufacturing and testing the solar panels and cells. the portability of this device is useful in quality assurance at various stages on the production line and can be taken from one location to another. when used in the installation of solar panels, the prova 200 solar panel analyzer assists in determining the proper inverter size as well as optimum power output position of panels and helps identify defective cells or panels that have worn out over time. the solar panel analyzer also provides the user with current and voltage (iv) test curves, maximum solar power as well as current and voltage. solar cell properties are easily determined using the following units: i-v curve test for solar cell, single point i-v test, maximum solar power (pmax) search by auto-scan, maximum voltage (vmaxp) at pmax, maximum current (imaxp) at pmax, voltage at open circuit (voc), current at short circuit (isc), i-v curve with cursor, efficiency (%) calculation of solar panel, scan delay setting. (0 ~ 9999 msec), solar panel area setting. (0.001 m2 ~ 9999 m2), standard light source setting. (10 w/m2 ~ 1000 w/m2), min. power setting for alarm function, built-in calendar clock, rechargeable batteries with built-in charging circuit, optical usb cable for pc and the terminals of the solar cell are connected as shown in fig.4. in this work, the system is consisted of four silicon solar cells (types a, b, c, and d) of different area as it is presented in fig.5. table 2 gives the general specification of these cells. table 1, general specifications of prova 200. battery type rechargeable, 2500ah (1.2v) x 8 ac adaptor ac 110v or 220v input dc 12v / 1~3a output dimension 257(l) x 155(w) x 57(h) mm weight 1160g / 40.0oz (batteries included) operation environment 0 ~ 50, 85% rh temperature coefficient 0.1% of full scale / 0c (＜18 or 0c＞28) storage environment -20 ~ 60, 75% rh accessories user manual x 1, ac adaptor x 1 optical usb cable x 1 rechargeable batteries x 8 software cd x 1, software manual x 1 kelvin clips (6a max) x 1 set abbas hamid sulaymon al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 57-68 (2013) 59 table 2 solar cell specifications. fig. 1. (a)test circuit (b)the i-v curve. type area m2 voc v isc a peak power w peak voltage v peak current a production date a 0.023 11 0.33 1.8 6.6 0.28 2010 b 0.228 12 2.2 18 9.0 2.0 1980 c 0.366 19.5 2.8 35 15.8 2.3 1986 d 1 22 8.1 130 18.5 6.0 2010 (a) (b) abbas hamid sulaymon al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 57-68 (2013) 60 fig .2. square area is the maximum power output of the solar cell. (a) (b) fig. 3. the prova 200 solar panel analyzer :(a) front view (b) top view. fig. 4. wires connections. iv plot abbas hamid sulaymon al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 57-68 (2013) 61 a b c d fig.5: solar cells tested type a, b, c and d 4. solar panel parameters measurements the main parameters that characterize a photovoltaic panel (fig.5) [4] are: • short circuit current (isc): the maximum current provided by the panel when the connectors are short circuited. • open circuit voltage (voc): the maximum voltage that the panel provides when the terminals are not connected to any load (an open circuit). • maximum power point (pmax): the point where the power supplied by the panel is at maximum, where pmax = imax x vmax. the maximum power point of a panel is measured in watts (w) or peak watts (wp). it is important to know that in normal conditions the panel will not work at peak conditions, as the voltage of operation is fixed by the load or the regulator. typical values of vmax and imax should be a bit smaller than the isc and voc. • fill factorn(ff): the relation between the maximum power that the panel can actually provide and the product isc. voc. this gives an idea of the quality of the panel because it is an indication of the type of iv characteristic curve. the closer ff is to 1, the more power a panel can provide. common values usually are between 0.7 and 0.8. • efficiency (η): the ratio between the maximum electrical power that the panel can give to the load and the power of the solar radiation (pl) incident on the panel. this is normally around 10-12%, depending on the type of cells (monocrystalline, polycrystalline, amorphous or thin film). the definitions of point of maximum power and the fill factor are: = pmax/pl=ff . isc . voc / pl …(1) 5. result and discussion the measuring results of the commercial available solar cells from different manufacturers are presented. cell samples have been investigated regarding their iv-characteristics at different solar intensities in a range 100-1000 w/m2and the ambient temperature between (22-26 ºc). all the measurements and the characteristics of these cells have been made within the date of february and march 2012. the data obtained for i-v characteristics and p-v curve for the silicon solar cell under the specific solar radiation intensities are shown in tables 3 to 6. a comparison is done between the cell parameters and performance of the solar cell. fig.6 shows the dependence of solar cell maximum power with solar radiation intensity for the four solar cell types. according to fig.7 solar cell type a and d have the high solar output efficiency due to earlier abbas hamid sulaymon al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 57-68 (2013) 62 production date as compared the other two types b and c. one can see in fig. 8 that the variation of fill factor of solar cells b,c, and d fluctuated, increased with maximum power increasing while fill factor of type a decreases with increasing maximum power. fig. 6. variation of solar cell maximum power with solar radiation intensity for the four solar cell types. fig. 7. variation of solar cell efficiency with solar radiation intensity for the four solar cell types. 0 20 40 60 80 100 120 0 200 400 600 800 1000 m ax im um p ow er ,p m ax ( w ) solar radiation intensity ,g (w/m2 ) a b c d 0 2 4 6 8 10 12 14 16 0 200 400 600 800 1000 1200 ef fic ie nc y , η solar radiation intensity ,g (w/m2 ) a b c d abbas hamid sulaymon al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 57-68 (2013) 63 fig. 8. variation of solar cell fill factor with maximum power for the four solar cell types. 6. correlation development in order to find a functional relationship between solar cell efficiency with the corresponding solar cell parameters ; solar irradiance g ,maximum power pmax and production date p, non-linear regression analysis have been used to available experimental data of solar cell as shown in tables 3 to 6 . the obtained correlation of the computer software program (statistica) is: η=(a1+a2g)(b1+b2p+b3p2)/(d1+d2(pmax+d3pmax 2 ))+c1+c2g+c3+c4pmax+c5pmax 2 … (2) a1= -1.227832 a2= -0.00608 b1=23102.47 b2=-21273.8 b3= 5297.8 c1=-608.795 c2=0.000785 c3=311.7824 c4=-0.166576 c5=0.000844 d1=-0.545443 d2=-0.007904 correlation coefficient (r) = 0.9777 table 7 shows the calculated solar cell efficiency and the corresponding percentage error. the average absolute error is 5.5% for 40 data point. table 3, solar cell type a with surface area 0.0237 m2 . g w/m2 vnow v voc v isc ma pmax w vmax v imax ma % ff 100 9.24 9.22 30.6 0.19 7.12 26.7 8.63 0.67 200 9.44 9.41 46.4 0.298 7.48 40.8 8.51 0.66 300 9.84 9.81 90.1 0.583 7.41 78.6 8.43 0.65 400 9.92 9.91 105.5 0.678 7.31 92.8 7.37 0.64 500 10.04 10.01 133.6 0.843 7.17 117.5 7.30 0.63 600 10.11 10.09 157.9 0.970 6.93 140.0 7.03 0.61 700 10.14 10.12 173.2 1.039 6.92 150.0 6.4 0.59 800 10.20 10.18 196.8 1.146 6.73 170.5 6.23 0.57 900 10.23 10.22 217.3 1.229 6.58 186.8 6.14 0.55 1000 10.37 10.36 256.7 1.394 6.42 217.3 6.06 0.52 abbas hamid sulaymon al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 57-68 (2013) 64 table 4, solar cell type b with surface area 0.228 m2. g w/m2 vnow v voc v isc ma pmax w vmax v imax ma % ff 100 9.39 9.29 217.3 1.23 7.19 172 5.41 0.61 200 10.09 10.07 458.9 3.02 8.97 337 6.62 0.65 300 10.18 10.16 536.9 3.50 9.14 393 5.2 0.65 400 10.34 10.32 732.6 5.36 9.14 586 5.8 0.70 500 10.40 10.39 823.0 6.16 9.05 680 5.4 0.72 600 10.56 10.54 1086 8.52 8.91 956 6.12 0.75 700 10.65 10.63 1240 9.94 8.75 1130 6.23 0.75 800 10.68 10.67 1300 10.29 8.79 1170 5.64 0.74 900 10.78 10.78 1450 11.58 8.79 1310 5.64 0.73 1000 11.02 11.03 1910 15.20 8.91 1710 6.69 0.72 table 5, solar cell type b with surface area 0.366 m2. g w/m2 vnow v voc v isc ma pmax w vmax v imax ma % ff 100 16.20 16.19 196 1.50 11.70 131 4.21 0.48 200 17.42 17.40 383 4.05 13.58 299 5.54 0.61 300 17.99 17.94 556 6.52 14.40 426 5.90 0.65 400 18.20 18.18 825 10.1 14.63 693 6.53 0.67 500 18.30 18.25 972 12.6 14.71 730 6.42 0.79 600 18.40 18.36 1106 14.1 14.81 952 6.37 0.69 700 18.50 18.49 1230 15.97 15.03 1060 6.23 0.69 800 18.80 18.79 1620 21.5 15.30 1400 7.30 0.70 900 18.89 18.88 1710 22.9 15.20 1507 6.90 0.70 1000 19.05 19.05 1950 26.4 15.40 1720 7.20 0.71 abbas hamid sulaymon al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 57-68 (2013) 65 table 6, solar cell type d with surface area 1 m2. g w/m2 vnow v voc v isc ma pmax w vmax v imax ma % ff 100 17.60 17.50 1200 13.92 17.40 800 13.92 0.66 200 19.10 19.00 1800 28.00 17.50 1600 14.00 0.81 300 20.50 20.50 2500 42.05 17.52 2400 10.50 0.82 400 21.01 21.00 3100 51.30 17.70 2900 12.80 0.78 500 21.09 21.08 3520 54.90 17.72 3100 10.98 0.73 600 21.14 21.13 3560 63.90 17.76 3500 10.60 0.84 700 21.25 21.24 4500 76.90 17.80 4300 10.90 0.80 800 21.40 21.39 5060 83.84 17.84 4700 10.48 0.77 900 21.51 21.52 5600 94.42 18.02 5240 10.49 0.78 1000 21.60 21.59 5800 100.70 18.31 5500 10.07 0.80 table 7, the calculated solar cell efficiency and the corresponding percentage error. cell type g 100 200 300 400 500 600 700 800 900 1000 a c 8.7 8.4 8.1 7.8 7.5 7.2 6.7 6.3 6.0 5.7 %e -1.1 1.4 4.2 -5.3 -2.2 -1.9 -4.4 -1.8 2.3 6.6 b c 5.6 5.6 5.6 5.8 5.8 6.0 6.1 6.1 6.1 6.1 %e -3.4 15.5 -7.7 0.8 -7.7 2.0 2.6 -8.2 -8.9 9.1 c c 4.5 5.0 5.7 6.5 6.8 6.9 6.9 6.8 6.8 6.6 %e -6.5 9.6 3.0 0.5 -5.5 -7.9 -11.4 6.2 1.3 7.8 d c 13.5 13.3 12.2 11.6 11.4 11.0 10.5 10.4 10.3 10.4 %e 3.0 5.1 -16.7 9.3 -4.4 -3.6 3.8 1.1 1.8 -3.0 7. conclusions the performance of a solar cell under sun radiation is necessary to describe the electrical parameters of the cell. effect of production date on the performance of a photovoltaic solar system was investigated. a correlation is developed between solar cell efficiency and with the corresponding solar cell parameters; solar irradiance g, maximum power pmax and production date p. the average absolute error of the proposed correlation is 5.5% for 40 data points. the results show that there is a fluctuated in solar cell efficiency with the values of irradiance. notation a ideality factor ff fill factor g solar radiation, w/m2 il photocurrent, a imaxp , imp maximum current at pmax , ma io saturation current, a ip operating current, a isc current at short circuit, ma p production date pl power of solar radiation, w abbas hamid sulaymon al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 57-68 (2013) 66 pmax maximum solar power, w rl load resistance, ω vmaxp , vmp maximum voltage at pmax, v voc voltage at open circuit, v efficiency, % 8. references [1] sze, s.m., "physics of semiconductor devices", 2nd ed., john-wiley,(1981). [2] king d. l., “photovoltaic module and array performance characterization methods for all system operating conditions”, proceeding of nrel/snl photovoltaics program review meeting, lakewood, november 1822(1996). [3] van der heide a.s.h., schonecker a., bultman j.h., and w.c. sinke, “explanation of high solar cell diode factors by nonuniform contact resistance”, progress in photovoltaics, , vol. 13, no1, pp. 3-16(2005). [4] castaner l. and s.silvestre, "modelling pv systems using pspice", wiley and sons. (2002). [5] gracia m. c. alonso, j. m. ruiz, and f. chenlo, “experimental study of mismatch and shading effects in the,” solar energy mater. solar cells, vol. 90, no. 3, pp. 329–340, feb. (2006). [6] khezzar r, zereg m, and a khezzar"laboratoire de physique energetique appliquee (lpea)", universite hadj lakhdar, 05000 batna, algeria r-khezzar@hotmail.com ,(2008). [7] wagner a. "peak-power and internal series resistance measurement under natural ambient conditions" eurosun conference, 2000 copenhagen, june 19-22 (2000). mailto:r-khezzar@hotmail.com )2013( 5768، صفحة2، العدد9مجلة الخوارزمي الھندسیة المجلد عباس حمید سلیمون 67 التكھن بكفاءة الخلیة الشمسیة وتقییم ادائھا في الظروف الجویة لمدینة بغداد شیماء عالء الدین مھدي عماد طالب ھاشم عباس حمید سلیمون جامعة بغداد/ كلیة الھندسة/ قسم ھندسة الطاقة الخالصة الختبار اربع الواح شمسیة 200 استعمل جھاز محلل اداء الخلیة بروفالقد . اداء الخلیة الشمسیة تحت االشعاع الشمسي ضروري لوصف معالم الخلیةان لخالیا شمسیة مختلفة وتحت تاثیر االشعاع الشمسي تیار -لقد تم فحص خصائص الفولطیة .نوع سیلیكون متعدد التبلور عند الظروف المناخیة لمنطقة بغداد اعلى قدرة ،شدة االشعاع الشمسي: تم ایجاد عالقة بین كفاءة الخلیة مع ما یقبلھا من معامالت الخلیة والتي ھي .لتحدید العوامل المثلى التي تعطي اعلى قدرة ان االلواح الشمسیة حدیثة الصنع اكثر كفاءة من نتائج البحث لقد بینت ، عملیةالربعین نقطة % ٥,٥معدل نسبة الخطأ المطلق یساوي . وتاریخ االنتاج .نظیراتھا قدیمة الصنع al-khwarizmi engineering journal al-khwarizmi engineering journal,vol. 11, no. 2, p.p. 8691(2015) dual measurements of pressure and temperature with fiber bragg grating sensor tahreer s. mansour* fahad m. abdulhussein** *,**institute of laser for postgraduate studies/ university baghdad *email: tahreer@ilps.uobaghdad.edu.iq **email: fahad_m2556@yahoo.com (received 16 september 2014; accepted 16 february 2015) abstract the fiber bragg grating (fbg) technology has been rapidly applied in the sensing technology field. in this work, uniform fbg was used as pressure sensor based on measuring related bragg wavelength shift. the pressure was applied directly by air compressor to the sensor and the pressure was ranged from 1 to 6 bar. this sensor also was affected by the external temperature so as a result it could be used as a temperature sensor. this sensor could be used to monitor the pressure of dams. it has been shown from the result that the sensor is very sensitive to the pressure and the sensitivity was (67 pm\bar) and is very sensitive to temperature and the sensitivity was (10pm\ o c). keywords: fiber bragg grating (fbg), fiber bragg grating analyzer (fbga), pressure sensor, effective refractive index. 1. introduction fiber bragg grating (fbg) sensors have been widely used in an increasingly large number of sensing applications due to their especially attractive characteristics such as intrinsical safety, immunity to electromagnetic fields, remote sensing, and large multiplexing capabilities [1]. these sensors can be widely found in medicine as well as in different experimental, developmental, and diagnostic processes. one of the fbg sensors is the pressure sensor which presents key technology for the safe operation of different technical products, systems, and technologies [2]. fbgs are spectral filters fabricated within the segments of optical fibers. they typically reflect light over a narrow wavelength range and transmit all other wavelengths, but they also can be designed to have more complex spectral responses [3]. figure (1) shows the structure and the spectrum of the fbg. fig. 1. structure of fbg and the reflection and transmission spectrum [4]. fbgs are formed by a periodic change of the fiber cored refractive index in direction of propagation of optical radiation. the bragg resonant wavelength is given by [2]: mailto:tahreer@ilps.uobaghdad.edu.iq mailto:fahad_m2556@yahoo.com tahreer s. mansour al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 8691 (2015) 87 𝜆𝑩 = 2𝑛𝑒λ ... (1) where λb is the bragg resonant wavelength, ne is the effective refractive index and λ is the periodic variation (pitch) of the fbg. the formation of fbg is generally based on the photo-sensitivity of silica fiber doped with germanium. when illuminated by uv radiation, the fiber exhibits a permanent change in the refractive index of the core [5]. the bragg resonant wavelength is determined by various factors applied on the fbg, which affect effectively refractive index or grating periodic variation; therefore, it is an indirect measurement resulting from modifying physical or geometrical properties of the fbg. pressure measurement is always based on the deformation of some sensing part (typically the membrane). applied stress on the fbg in the direction of the fiber axis results in the extension of its physical dimensions and in the change of the periodic variation [2]. a lot of research is done on fbg sensors, especially concerning pressure measurement, but since fbg intrinsic pressure sensitivity is not very high, those sensors are always designed to amplify the pressure measurement indirectly by sensing the strain instead .our approach consists of mounting the fbg sensor in cylindrical assemblies so that increased pressure sensitivity is achieved though mechanical amplification schemes [6]. the wavelength variation (∆𝜆) caused by the axial strain change (∆𝜀) and the temperature change (∆t) could be given by [1]: ∆λ/λ= (1-𝜌𝑒) ∆ε + (αf +ξ) ∆t ... (2) where λ is the initial wavelength of fbg, 𝜌𝑒 , αf and ξ are the effective photoelastic coefficient, the thermal expansion coefficient, and the thermal-optic coefficient of fused silica fiber respectively. in this work, the capability of the fbg sensor to be used as pressure and temperature sensor was investigated and at different sets of powers from the source. the relationship between the shift of the bragg wavelength of fbg and the applied pressure and temperature can be expressed as [7]: ∆𝝀 𝝀 = 𝑘𝑝 𝛥𝑝 + 𝑘𝑇𝛥𝑇 … (3) where 𝑘𝑝 is the pressure sensitivity and 𝑘𝑇 is the temperature sensitivity. this equation is a general expression that describe the amount of shifting that caused by pressure and temperature while eq. 2 described the amount of shifting due to strain and temperature. the effects of pressure and temperature on fwhm of bragg wavelength were discussed. a general expression for the approximate fwhm bandwidth of a gratings that inscribed inside a core of fiber with no refractive index is given by [8]: ∆λ = 𝜆𝑩𝑠 ∆n 𝑛𝑜 2 + 1 n 2 ... (4) where n is the number of the grating planes and ∆n is the amplitude of the induced refractive index perturbation. the parameter s is ~1 for strong gratings (for grating with near 100% reflection) whereas s ~ 0.5 for weak gratings. 2. experimental setup the measurement setup consists of an optical signal source which is superluminescent diode with temperature controller ted200c and laser diode controller ldc210c (both ted and ldc are made from thorlabs company). the laser mount is the main part of the source. ic chipset (covega company) is fixed on it. ic chipset is connected to a single mode fiber (smf) that is terminated by an fc connector to the first port of a 3-port circulator (thorlabs company). the second port is connected by an fc connector to the fbg sensor and the third port is connected to the fiber bragg grating analyzer (fbga) (bay spec company). the fbg sensor (welltech instrument company) is designed to measure fluid pressure or levels. there are double fbgs that inscribed on smf inside stainless steel housing named as fbg1 with λb = 1545.748 nm and fbg2 with λb = 1550.710 nm. the reflectivity and the gratings length for both fbgs are 99% and 3cm respectively. fbg2 is used to measure the pressure. simultaneously, as temperature is compensated, fbg1 is used to monitor temperature. the pressure was applied by air compressor with pressure ranged from (1 to 6) bar. the fbg sensor was also affected by change of external temperature when it was immersed in water and heated. the reflected signal from the sensor is analyzed by fbga and the program (sense20\20) analyzed the reflected data. figure (2) shows the fbg sensor and the experimental setup was shown in figure (3). tahreer s. mansour al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 8691 (2015) 88 fig. 2. fbg sensor head. fig. 3. experimental setup. next figure shows the light source which consist of laser mount that including the ic chipset, and also tdc and ldc. (a) (b) fig. 4. light source: a. tdc and ldc. b. laser mount and ic chipset. 3. results and discussion at the first the two peaks of the fbg sensor that analyzed by the fbga through the software program sense (20/20) that connected to the fbga with no pressure applied and with 30 ˚c the temperature of the water with 280ma applied to the fbg sensor from ldc are shown in figure (5). fig. 5. the spectrum of the sensor. the wavelength spacing between the two peaks is about 5 nm. when the fbg sensor is connected to the air compressor and the pressure start to increase, the characteristics curve of the pressure sensor can be measured. figure (6) shows the spectral response of the fbg sensor with different sets for the power of the optical signal that goes to the fbg sensor. the power was varied by varying the ldc and tdc. the pressure sensitivity was calculated to be 67 pm/ bar for the pressure range from (1 to 6) bar with step of 1 bar. fig. 6. bragg wavelength shift against pressure at different sets of powers. according to eq.1 the pressure will affect the pitch of the grating. table (1) shows the value of pitch of grating with different sets of pressure with i=240ma, tec=40℃, pin=1.68mw. pressure applied on fbg sensor will affect its physical dimensions and changes the grating period [2]. tahreer s. mansour al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 8691 (2015) 89 table 1, pressure with grating period. pressure (bar) bragg wavelength (nm) grating period (nm) 1 1550.620 545.914 2 1550.558 545.892 3 1550.493 545.869 4 1550.412 545.840 5 1550.364 545.824 6 1550.299 545.801 figure (7) shows the relation between the grating period and bragg wavelength. fig. 7. grating period against bragg wavelength. when the fbg sensor was immersed in water and the water was heated and the temperature was varied, the thermal expansion of the stainless steel will add another thermal effect on the second fbg of the pressure, thus the two fbgs respond to the thermal effect differently. in figure (8) there will be no pressure applied and the temperature increased from (20 to 70) ˚c with step of 5 ˚c and this figure shows the peak of temperature (fbg1). fig. 8. first peak shift (fgb1) with temperature increased. in figure (9) the peak of the pressure (fbg2) will be shifted too but the bragg wavelength here will increase as shown figure (9) for the same range of temperatures. fig. 9. second peak shift (fbg2) with temperature increased. the two peaks were shifted to higher wavelengths with increasing the value of temperature. under the influence of strain or temperature changes, the effective refractive index and the grating period of fbg will change that result in the change of center wavelength of fbg [9] and that showed in eq.(2). the fwhm for the two fbgs were changed during the heating process and figure (10) shows the change of fwhm for the two peaks with i=240ma, tec=50℃, pin=1.68mw. fig. 10. fwhm change with temperature increased for fbg1 and fbg2. when only pressure was applied the fwhm for the two peaks was not affected. tahreer s. mansour al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 8691 (2015) 90 4. conclusions 1. simultaneous measurements of temperature and pressure were achieved for dual peaks sensor setup. fbg1 and fbg2 were sensitive to the variation of temperature with sensitivities of 10 pm/ ˚c and 9.2 pm/ ˚c for the temperature range from (20 to 65) ˚c as shown in figures (8 and 9). 2. fbg2 was sensitive to the variation of pressure with 67 pm/ bar sensitivity for the pressure range from (1 to 6) bar as shown in figure (6). 3. the fwhm was changed for the two peaks during the heating process but its relation was nonlinear with temperature as shown in figure (10). fwhm was not affected when only pressure was applied. 5. references [1] j. huang, z. zhou, d. zhang and q. wei ''a fiber bragg grating pressure sensor and its application to pipeline leakage detection'' hindawi, vol. 53 (2013). [2] f. urban, j. kadlec, r. vlach and r. kuchta '' design of a pressure sensor based on optical fiber bragg grating lateral deformation'' sensors vol. 10, pp. 1121211225 (2010). [3] r. sharma, r. rohilla, m. sharma and t.c.manjunath ''design & simulation of optical fiber bragg grating pressure sensor for minimum attenuation criteria'' journal of theoretical and applied information technology, new horizon college of eng. bangalore, karnataka, india (2004). [4] liu yimin, wang jie, ji weifeng, zhou ce and chen wenjun ''research and application of fiber bragg grating sensor in geological disaster automation monitoring'' international journal of control and automation, vol. 7, pp. 1-12 (2014). [5] cheung chi shing ''an investigation of chirped fiber bragg gratings fabry-perot interferometer for sensing applications'' ph.d thesis, optical sensor group, center of photonics and optical engineering, school of engineering (2004). [6] e. pinet ''pressure measurement with fiberoptic sensors: commercial technologies and applications'' 21st international conference on optical fiber sensors, edited by wojtek j. bock, jacques albert and xiaoyi bao,proc of spie vol.7753 (2011). [7] shilie zheng and xianmin zhang "simultaneous measurement of pressure and temperature using a single fiber bragg grating" progress in electromagnetics research symposium, hangzhou, china (2005). [8] qiying chen and ping lu ''fiber bragg gratings and their applications as temperature and humidity sensor" nova science publishers, canada (2008). [9] v. kumar , b. c. choudhary and umesh k. tiwari ''fbg temperature sensor for avionics display system'' advances in aerospace science and applications, vol.3 no.1, pp. 111 (2013). (2015)8691 ، صفحة 2، العذد11دالخوارزمي الهنذسية المجلجلة م تحرير صفاء منصور 91 المحزز نوع براغ غط باستعمال متحسس الليف البصريس المزدوج للحرارة والض القيا **فهد محمد عبد الحسين* منصورتحرير صفاء جامعة بغداد/ العليامعهد الليزر للدراسات **،* tahreer@ilps.uobaghdad.edu.iq : االلكتروني البريد * fahad_m2556@yahoo.com : االلكتروني البريد** الخالصة في هذا العمل استعمل الليف البصري المحزز نوع . استخدم مؤخراً وبصورة متسارعة الليف البصري المحزز نوع براغ في تقنية بناء المتحسسات تم تسليط الضغط بصورة مباشرة باستعمال ضاغط الهواء بضغط . قياس ازاحة طوله الموجي عن طريقللضغط امتحسسبوصفه براغ منتظم الترتيب بعد انجاز العمل وجد ان تحسس هذه المنظومة . للحرارة ايضاً متحسساتاثر هذا المتحسس ايضا بالحرارة الخارجية لذلك استعمل . بار ( 6-1)اوح من يتر pm/c) حساسية جيدة وحساسيته للحرارة هي تعدوالتي ( pm /bar60) ذات الفايبرين المحززين نوع براغ قد تحسست للضغط بحساسية o 10 . ) mailto:tahreer@ilps.uobaghdad.edu.iqالبريد mailto:tahreer@ilps.uobaghdad.edu.iqالبريد mailto:fahad_m2556@yahoo.com**البريد mailto:fahad_m2556@yahoo.com**البريد <4d6963726f736f667420576f7264202d2039322d20313032d3d1ec20e6cec7e1cf20ccc7c8d120e6cec7e1cf20e6e1edcf> al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 14, no. 4, december , (2018) p.p. 92102 classical and statistical optimization of medium composition for promoting prodigiosin produced by local isolate of serratia marcescens sura jasem mohammed* khalid jaber kadhum** khalid waleed hameed*** *,***department of biochemical/ alkhawarizmi collage of engineering/ university of baghdad/ baghdad/ iraq **department of biotechnology/ college of science/ university of baghdad/ baghdad/ iraq *email: sura.breig@yahoo.com **email: khalidjaber@scbaghdad.edu.iq ***email: kwhameed74@yahoo.com (received 26 december 2017; accepted 19 march 2018) https://doi.org/10.22153/kej.2018.03.006 abstract prodigiosin is a ‘natural red pigment produced by serratia marcescens which exhibits immunosuppressive and anticancer properties in addition to antimicrobial activities. this work presents an attempt to maximize the production of prodigiosin by two different strategies: one factor at time (ofat) and statistical optimization. the result of ofat revealed that sucrose and peptone were the best carbon and nitrogen sources for pigment production with concentration of prodigiosin of about 135 mg/ l. this value was increased to 331.6mg/ l with an optimized ratio of c/n (60:40) and reached 356.8 with ph 6 and 2% inoculum size at end of classical optimization. statistical experimental design based on response surface methodology was conducted to optimize the composition of trace element. the design revealed that the predicted prodigiosin production of 406 mg/l can be achieved when concentrations of trace element cacl2·2h2o, feso4·4h2o, mgso4·7h2o and mnso4·4h2o were equal to 9.22, 0.32, 0.67 and 2.48 g/l, respectively. the actual production of prodigiosin in the optimized medium was 375�12 mg/l. growth kinetics of s. marcescens were evaluated in optimized medium which revealed that prodigiosin was ‘non-associated growth’ secondary metabolite with maximum production of approximately 365.7 mg/l obtained after 54 hours of incubation. keywords: classical optimization, prodigiosin, serratia marcescens , statistical optimization. 1. introduction prodigiosin is a ‘red pigment produce by serratia marcescens which is gram-negative bacteria belong to the family of’ enterobacteriaceae [1]. it is belong to ‘the family of prodiginines which are a group of tripyrrole red pigments produce as a secondary metabolite by many terrestrial (soil) and marine bacterial strains’ including species of serratia, ‘mainly s. marcescens [2]. in recent years, there has been an increasing interest in prodiginines compounds due to their immune suppressive and anticancer properties in addition to antimicrobial’ activities [3]. the common ‘way for improving production of antibiotic is to optimize one independent variables while, other independent variables remain’ constant. however, the experimental results ‘obtained from such strategy are not reflecting the interaction effect between factors. optimum values of factors are difficult to determine from experiment simply due to large number of experiment’ required. therefore statistical optimization technique ‘was developed to reduce the number of experiments that optimize all independent variables in order to maximize the response (dependent variable)as well as build models evaluating effect of factors on response’ sura jasem mohammed al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 92102 (2018) 93 [4]. the aim of the present study was to find the optimal medium composition for cultivating the local isolate serratia marcescens in order to improve the production of prodigiosin. 2. experimental works 2.1 microorganisms and media prodigiosin producing isolate of serratia sp. was used throughout this work. it was provided by fermentation laboratory, department of biotechnology, collage of science, university of baghdad. brain heart infusion was used for maintenance of s. marcescens. a chemically defined liquid medium described by chen and coworkers (2013) [5] was used for the cultivation of serratia and production of prodigiosin which contains g/l: (starch, 10; peptone, 5; cacl2.2h2o, 8.82; feso4.4h2o, 0.33; mgso4.7h2o, 0.61; mnso4.4h2o, 2). ph was adjusted to 7 prior to autoclaving. 2.2 preparation of inocula and cultivation methods seed culture of serratia marcescens isolate was prepared as follows: ‘a few loop full of bacterial growth from an overnight culture on brain-heart infusion medium was inoculated into 100 ml erlenmeyer shake flask contained 20 ml of chemically defined liquid medium. the flask was then incubated for 24 hr in an orbital shaker incubator at 30oc and 200 rpm which then used as seed culture for inoculating production medium at level of 2% (v/v) under the same incubation conditions for’ 48h. during the incubation, samples were taken for the analyses of prodigiosin production, biomass and substrate concentration. each run was conducted either in triplicate or duplicate. 2.3 classical optimization prodigiosin production was primarily optimized by classical method one factor at time with the parameters carbon and nitrogen sources, c/n ratio, ph and inoculum size%. for this purpose, different carbon sources (glucose glycerol, methanol, sucrose, arabinose, mannitol, mannose, methyl cellulose, starch, maltose) and nitrogen sources (urea, peptone, trypton, yeast extract, ammonium oxalate, ammonium acetate) were investigated. the best concentration ratio of carbon to nitrogen sources that maximize prodigiosin production was studied using different ratios of (c/n) (9/1, 8/2, 7/3, 6/4, 1/1, 4/6, 3/7, 2/8, 1/9). in addition, the effect of ph (5 to 9) and size of seed culture (1 to 5%) were also investigated. 2.4 statistical experimental design response surface methodology (rsm) was used to ‘optimize trace elements concentrations (micronutrients) that maximize prodigiosin production based on a statistical method using box-bhenken with three levels for each factor and design matrix as shown in table (1). the effects of ‘each variable and their interaction as well as the statistical analysis were studied in order to obtain a predict production as explained in the following quadratic’ equation[6]: � = �� + ���� + ��� ������ + ��� ������� ��� �� ��� …(1) where y is the predicted response, β0 is the intercept term, βi is the linear effect, βii is the squared effect, βij is the interaction effect, and xi and xj are input variables that influence the response variable y. the experimental ‘design and regression analysis of experimental data was conducted with design expert7 analysis of variance anova to evaluate the model. the quality of the polynomial model equation was judged statistically by the determination coefficient (r2), and its statistical significance was determined by fisher’s’ test [7]. 2.5 growth kinetics study of serratia marcescens the behavior of serratia marcescens in ‘terms of growth and substrate consumption with time as well as prodigiosin production in the optimized and un-optimized medium was studied. fifty ml of the chemically defined liquid medium was prepared in 250 ml erlenmeyer flasks contained. after autoclaving, the flasks were inoculated with the optimal size of serratia inoculum and incubated in an orbital shaker at 30°c and 200rpm for 48hrs. samples were taken at different time during the incubation period at 0 time and after (3, 6, 12, 15, 18, 33, 48, 51, 54, 63) hours of the incubation for the determination of biomass, substrate concentration and prodigiosin. sura jasem mohammed al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 92102 (2018) 94 2.6 analytical methods prodigiosin concentration was ‘determined by a colorimetric method [8]. biomass concentration of serratia marcescens growth was measured as dry weight of cell weight (dcw). briefly, methanol was used to extract prodigiosin from the cell pellets for at least three hours. then, centrifuge at 10000 rpm for 10 min was used to remove cell debris and the absorbance at 530 nm of supernatant was’ determined by spectrophotometer (aurora instrument ltd-u.k). the concentration of prodigiosin was detected according to the following equation prodigiosin g/ l = (o.d.530 *323.4 *dilution factor)/ 7.07 *104 ...2 where: o. d530: optical density nm; 323.4: molecular weight of prodigiosin; e530 =7.07*104 m-1 cm-1 (molar extension coefficient of prodigiosin at 530 nm); dilution factor = final volume / initial volume starch concentration in the fermented broth was determined by iodine test based on the reaction between iodine/potassium iodide and starch (amylose and amylopectin) that resulting a change in the colour [9]. the absorbance is measured at 580 nm. sucrose concentration was measured in term of glucose concentration after hydrolysis of sample in acid solution [10], the glucose concentration was detected by enzymatic colorimetric method (c cromatest). 3. results and discussion the optimization of cultural parameters that required for elevating prodigiosin production was conducted by classical optimization method such as carbon and nitrogen sources, ph and inoculum size. some physical parameters that were not investigated in this study have been adjusted according to the literature such as agitation rate in the shaker 200 rpm and temperature 300c [5]. 3.1 classical optimization of medium composition different ‘carbon sources were investigated to find the best and most suitable carbon source for prodigiosin production. ‘based on the literature, s. marcescens is capable of consuming a wide range of different carbon sources including monosaccharides (e.g. glucose), disaccharides (e.g. sucrose and maltose) as well as polysaccharide (e.g. starch) to produce energy and’ metabolites [11]’. ‘according to the results, s. marcescens was able to metabolize all types of carbon sources used in this study for growth. as shown in figure (1) prodigiosin production was observed with media supplemented with glycerol, mannitol, mannose, sucrose and maltose and decrease in other media. maximum production is achieved with sucrose 130.7 mg/l. prodigiosin as a secondary metabolic product is produced in the stationary phase. in general, simple carbon sources are consumed in the growth phase and therefore, are not supporting secondary metabolite production as it noted in the culture supplemented with’ glucose. fig. 1. the effect carbon source on prodigiosin production by s. marcescens in chemically defined liquid medium. nitrogen sources ‘cannot be neglected during prodigiosin production and other antibiotics. it has been shown that antibiotic production by many microorganisms is influenced by the type and concentration of nitrogen sources in the culture medium [12]. as shown in figure (2), most of nitrogen sources used in this study except peptone did not support the production of prodigiosin by s. marcescens. the maximum prodigiosin production of 139.34 mg/l was achieved in the culture contained peptone as a nitrogen source. whereas, the minimum pigment production was observed with ammonium acetate 7.47 mg/l. the use of complex nitrogen sources for antibiotic production is favourable because these sources may help to create physiological conditions in trophophase which favour antibiotic production in idiophase [13]. in this context, wei and coworkers’ [14] demonstrated that prodigiosin production was increased with peptone because it contains certain amounts of pyrrole amino acid. on the other hand, low prodigiosin production sura jasem mohammed al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 92102 (2018) 95 with ammonium sulfate was observed in the work undertaken by [15]. fig. 2. the effect of nitrogen sources on prodigiosin production by s. marcescens in chemically defined liquid medium. the requirements of ‘carbon in living organisms are usually larger than nitrogen and therefore the balance between the concentrations of them in the culture medium is an important aspect as it can determine how microorganisms use these sources [16,17]. thus, in order to enhance the production of prodigiosin, c/n ratios of 1:1,1:9, 2:8, 3:7, 4:6, 6:4 , 7:3 , 8:2 and 9:1in the medium were investigated. it was found that microbial growth and production of prodigiosin was significantly affected at high c/n ratio figure (3). the optimal c/n concentration ratio of 6/4 was found to be the best ratio that conferred the maximum prodigiosin production. the maximum concentration of prodigiosin obtained in this culture’ was331.6 mg/l. fig. 3. the effect of carbon to nitrogen ratio on prodigiosin production by s. marcescens in chemically defined liquid medium. microbial growth and synthesis of ‘secondary metabolite are highly affected by ph of the medium, therefore it was important to identify the optimum ph that maximize prodigiosin production. as illustrated in figure (4), maximum production of prodigiosin356.8 mg/l was obtained at ph 6. when the ph of the medium was less or more than 7, prodigiosin production was consequently’ decreased. fig 4. the effect of ph on prodigiosin production by s. marcescens in chemically defined liquid medium. inoculum size represents an ‘important factor in the fermentation process that usually affects the production of metabolites. therefore, this factor was investigated in this study using different inoculum size ranging from 1 to 5% (v/v). as shown in figure (5), maximum prodigiosin production was obtained when inoculum size was used at 2% (v/v) level yield in approximately 354.6 mg/l under the experimental conditions used in this work. the results showed that prodigiosin production was significantly decreased with less or more than that inoculum size. in this context, mahmoud [18] have found that the best inoculum size for the maximum production of prodigiosin’ was 2%. sura jasem mohammed al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 92102 (2018) 96 fig 5. the effect inoculum size on prodigiosin production by s. marcescens in chemically defined liquid medium. 3.2 statistical optimization of medium composition in this study, composition of trace element was optimized by statistical experimental design based on response surface methodology. four variables representing the concentrations of cacl2·2h2o, feso4·4h2o, mgso4·7h2o and mnso4·4h2o were selected to determine the optimal composition that maximizes prodigiosin production [19]. the trace compounds were used in three levels for each variable using box– behnken design which provided twenty-nine experiments as shown’ in table (1). table 1, coded experimental design and results for the response surface of prodigiosin production from s. marcescens as a function of trace element concentration. run cacl2 (g/l) feso4 (g/l) mgso4 (g/l) mnso4 (g/l) prodigiosin (mg/l) actual predict 1 9 0.3 0.6 2 391 396.4 2 8 0 0.6 2 15.5 33.78 3 8 0.3 1.2 2 275 261.8 4 10 0.3 0.6 3 450 380.4 5 9 0.3 0.6 2 396 396.4 6 8 0.6 0.6 2 100 110 7 9 0 0.6 1 0.567 26.4 8 9 0.3 0 1 154.4 174.8 9 9 0.3 0 3 259 272.6 10 9 0 0.6 3 0.14 67.76 11 9 0.6 0 2 0.14 22.01 12 10 0.6 0.6 2 65 81.3 13 9 0.3 0.6 2 400 396.4 14 10 0 0.6 2 0.141 24.60 15 8 0.3 0 2 241.6 221.7 16 10 0.3 1.2 2 220.5 255.5 17 9 0.6 1.2 2 110.3 124.9 18 9 0.3 1.2 3 280 294.1 19 9 0 0 2 70 5.57 20 8 0.3 0.6 3 246 230.8 21 8 0.3 0.6 1 313.2 323.1 22 9 0.3 0.6 2 405 396.4 23 10 0.3 0 2 161.6 190.0 24 9 0.6 0.6 1 120 67.7 25 9 0.6 0.6 3 170 159.4 26 9 0.3 1.2 1 238 258.96 27 9 0.3 0.6 2 390 396.4 28 10 0.3 0.6 1 180 145.3 29 9 0 1.2 2 80 8.32 based on values of response determined in designed experiment, empirical improved model was generated. the insignificant coefficients which are represented by terms (ab, ac, bc and bd) which p-value greater than 0.5 were omitted except cacl2·2h2o due to it is hierarchical model [20]: y = +396.49.5(a)+33.26(b)+26.42(c)+33.25(d)+84.30(ad) -70.92(a2)-263.02(b2)-93.17(c2)-53.08(d2) ...(3) sura jasem mohammed al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 92102 (2018) 97 where y ‘denoted predicted response of prodigiosin in mg/l and a, b, c, d denoted to cacl2·2h2o, feso4·4h2o, mgso4·7h2o and mnso4·4h2o concentration in g/l’ respectively. the significance of empirical model was examined by fisher test and analysis of variance for response’ surface. second order model is given in table (2) in which f-value 32.37 and p<0.0001implies that the model is highly significant. the fitness of model can be determined by determination coefficient (r2) [21].the r2value 0.9388 indicated that 93.8% of total experiment are explained by the model. the adequate precision used to measure signal to noise, it is believed to be desirable greater 4.here the value 16.644 revealed that the empirical model is of an adequate signal, and can be used to navigate the design space. the “pred r squared” 0.8208 were in reasonable agreement with the” adj r-squared” 0.9098. the coefficient estimates of eq. (3), along with the corresponding p values are given in table (2). the p value implies the significant of each factor and its important on prodigiosin production. as can be seen in table (2) feso4·4h2o* feso4·4h2o (b2) is the most significant with f-value 274.85 and p<0.0001. table 2, analysis of variance (anova) for the quadratic modal of prodigiosin production obtained from the experimental results source sum of square df mean square f-value p value prob> f model 5.2*105 9 58607.0 32.3 0.0001* a 1083.1 1 1083.16 0.6 0.448** b 13272.8 1 13272.8 7.33 0.0140* c 8373.56 1 8373.56 4.62 0.0446* d 13263.6 1 13263.6 7.33 0.0140* ad 28425.9 1 28425.96 15.7 0.0008* a2 32628.7 1 32628.7 18.0 0.0004* b2 4.4*105 1 4.48*105 274 0.0001* c2 56309.3 1 56309.3 31.1 0.0001* d2 18277.2 1 18277.2 10.0 0.005* residual 34400.0 19 1810.53 lack of fit 34242.8 15 2282.85 58.0 pure error 157.2 4 39.30 0.0007* cor total 5.61*105 28 r2=0.9388 r2adj=0.9098 r2pred= 0.8208 adeq precision =16.644 *significant**in significant response surface methodology provides ‘method of visualizing interaction between independent variables and response by contour plot [22]. the maximum prodigiosin (403.389 mg/l) dominant red region when concentration of cacl2.2h2o was 9.19 g/l and mnso4.4h2o was 2.45 g/l. the minimum prodigiosin production (175.55mg/l) which dominant green region when concentration of mnso4.4h2o and cacl2.2h2o were 1.03 and of 9.9 g/l respectively as explain’ in figure (6). fig. 6. effect of interaction factors cacl2 and mnso4 in medium composition for prodigiosin production. sura jasem mohammed al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 92102 (2018) 98 3.3 validation of optimum condition based on the enhanced regression model, optimization plot can be generated using the design expert 7 software in order to determine the optimum trace element in the medium composition for prodigiosin production. ‘the optimum concentrations of cacl2 .2h2o, feso4.4h2o, mgso4.7h2o and mnso4.4h2o using statistical media optimization are 9.22, 0.32, 0.67 and 2.48 g/l respectively’. the ramps chart for statistical optimization is explained by figure (7) . fig. 7. ramp chart for numerical optimization condition of prodigiosin based on box –behnken design matrix ‘ in order to verify the optimization result and determine accuracy of model, an experiment was conducted in duplicate with optimized media contain 9 g/l sucrose, 6 g/l peptone and the optimum concentrations of cacl2 .2h2o, feso4.4h2o, mgso4.7h2o and mnso4.4h2o as shown in figure (7) with ph value 6 and inoculum size 2%. the results showed that response of prodigiosin yield of s. marcescens was 375�12 mg/l which is nearly approximate to the predicted value’. 3.4 growth kinetic study of s. marcescens in shake flask s. marcescens ‘produce only low quantities of prodigiosin in un-optimized medium. the onset production of prodigiosin occurred after 6 hrs of inoculation and reached its maximum after 42hr to 10.95 mg/l. the maximum biomass concentration of 22.4 mg/5ml was observed after 33hr in which starch concentration was dropped from 9.5 g/l to 3.9 g/l figure (8). on the other hand, optimized medium stimulated production of prodigiosin by s. marcescens. as explained in figure (9), production of prodigiosin started after 3hrs after inoculation and reached its maximum of 365.71 mg/l at 54 hr of incubation’. furthermore, maximum biomass obtained was 9.4mg/ml and sucrose concentration dropped from 4.61 g/l to 0.019 g/l during 63 hr. fig. 8. time course of cell growth (■), substrate consumption (■) and prodigiosin production (■) by s. marcescens in un-optimized medium in shaker incubator at 200 rpm and 30 °c. sura jasem mohammed al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 92102 (2018) 99 fig. 9. time course of cell growth (■), substrate consumption (■) and prodigiosin production (■) by s. marcescens in optimized medium in shaker incubator at 200 rpm and 30 °c. 3.5 kinetic and stoichiometric parameters the kinetic and stoichiometric parameters associated to prodigiosin production, growth of s. marcescensand substrate consumption in both statistically optimized and un optimized medium in shake flasks are presented. the stoichiometric and kinetics parameters were evaluated according [23].table 3 presented a comparison between these parameters which showed that the maximum biomass and prodigiosin production was obtained in shake flask experiment using the optimized medium. it was found that, the most notable different in prodigiosin yield was in relation to substrate consumption. table 3, stoichiometric and kinetic parameters associated with prodigiosin and s. marcescensgrowth calculated from experimental result of shaking flask. stoichiometric and kinetic parameters shaking flask optimized medium un-optimized medium xmax (mg/ml) 9.4 4.48 pmax (mg/l) 365.7 10.95 (% )s∆ 0.9957 0.5826 µmax h-1 0.0733 0.0693 yx/sg/g 1.72 0.594 yp/s mg/g 79.629 2.0909 yp/x mg/g 46.29 3.97 pp (mg/l. h) 6.772 0.2609 qp(mgprod/gcell.h) 0.720 0.058 µ h-1 0.333 0.1666 td h 9.44 9.99034 ks g/l 0.0196 4.2784 4. conclusion prodigiosin production by s. marcescens in the chen’s medium was low (13.1 mg/l) and therefore, medium optimization is necessary to enhance prodigiosin production. based on results, prodigiosin production significantly increased by 10 fold with sucrose and peptone as carbon and nitrogen sources. additional increased in prodigiosin production by 3.45 fold was obtained with 60/40 carbon nitrogen ratio and with ph 6 and inoculum size 2%. further increased was also achieved with rsm to optimize the concentrations of trace elements in the production medium. according to rsm, the maximum predicted prodigiosin production of 406 mg/l can be achieved when concentrations of trace element cacl2·2h2o, feso4·4h2o, mgso4·7h2o and mnso4·4h2o were 9.22, 0.32, 0.67 and 2.48 g/l respectively. the growth profile of serratia marcescens in shake flake in optimized medium revealed that prodigiosin was ‘non-associated growth’ secondary metabolite. nomenclature ks limiting substrate g/l pmax maximum prodigiosin production g/l qp prodigiosin production to cell per hour (gprodigiosin/gcell.h) δs % substrate consumption td biomass doubling time (h) x biomass concentration (g /l) x max maximum biomass concentration (g /l) yx/s yield factor of biomass to substrate yp/ x yield factor of prodigiosin to biomass μ growth rate (h-1) μmax maximum specific growth rate (h-1) dcw dry cell weight od optical density bbd box-behnken design anova analysis of variance acknowledgments the authors are grateful to the management of baghdad university for providing the facilities to conduct this research work. sura jasem mohammed al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 92102 (2018) 100 5. references [1] ogba, o. m., mandor, b. i. and omang, h. m. 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(2008). red to redthe marine bacterium hahellachejuensisand its product prodigiosin for mitigation of harmful algal blooms.journal of microbiology and biotechnology, 18(10), 1621-1629. [20] [20] dutka, m., ditaranto,m., and løvås, t.(2015). application of a central composite design for the study of nox emission performance of a low nox burner. energies, 8, 3606-3627; doi:10.3390/en8053606. [21] osorio nm, ferreira-dias s, gusmao jh, fonseca mmr (2001) response sura jasem mohammed al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 92102 (2018) 101 surfacemodeling of the production of v-3 polyunsaturated fatty acids-enriched fats by a commercial immobilized lipase. j molcatal b enzym 11:677–686. doi:10.1016/s13811177(00)00156-9. [22] dey g, mitra a, banerjee r, maiti br (2001) enhanced production of amylase by optimization of nutritional constituents using response surface methodology. biochemeng j 7:227–231. doi:10.1016/s1369 703x(00)00139-x [23] luti k. j. k. and mavituna, f.(2011). elicitation of streptomyces coelicolor with dead cells of bacillus subtilis and staphylococcus aureus in a bioreactor increases production of undecylprodigiosin. biotechnological product and process engineering. 90:461–466. )2018( 92102، صفحة 4د، العد14دجلة الخوارزمي الهندسية المجلمسرى جاسم محمد 102 من عزله محليه لبكتريا تحديد الظروف المثلى للوسط المنتج للبرودجيوسين serratia marcescens الطريقه التقليديه و االحصائيهباستخدام ***خالد وليد حميد **خالد جابر كاظم *سرى جاسم محمد جامعه بغداد /كلية الهندسه الخوارزمي /الكيمياء االحيائية الهندسه قسم *,*** جامعه بغداد /كليه العلوم /ةت االحيائيقسم التقنيا ** sura.breig@yahoo.com*البريد االلكتروني: khalidjaber@scbaghdad.edu.iq**البريد االلكتروني: yahoo.com74kwhameed@***البريد االلكتروني: الخالصة الصفات التي تميز هذا الصبغه الحمراء تحمل صفات تؤهلها لتكون ماده اوليه في الصناعة ومن اهمالبرودجيوسين واحدا من اهم المواد التي يٌعد ت الى امكانيه الى ان العديد من البحوث التي اشار فضالً عنهي فعاليتها ضد العديد من المايكروبات s.marcescensالمايكروبيه المنتجه من قبل بكتريا ً استخدامه كمثبط ً مناعي ا الدراسة الحاليه صممت اليجاد الظروف المثلى النتاج الصبغة الحمراء باستخدام الطريقة التقليدية .لالورام السرطانيه اً و مضاد ا افضل نسبة كربون و 60:40 أفضل مصدر نايتروجينيبوصفه البيبتون ن السكروز يعد افضل مصدر كربون والنتائج ا وقد بينتاليجاد الظروف المثلى وتضمنت الخطوة الثانية أيجاد . لتر/ملغم ٣٦٥وكانت االنتاجيه في نهاية هذة الخطوة هي افضل حجم لقاح %٢ي و أفضل رقم هيدروجين ٦,الى نايتروجين o, 2h2·2caclى وكانت النتائج لتراكيز االمالح افضل التراكيز لالمالح الموجودة في الوسط بأستخدام الطريقة االحصائية اليجاد الظروف المثل o2h7·4o, mgso2h4·4fesoو وg/l 2.48, 0.67, 0.32, 9.22 o2h4·4mnso بينما القيمة لتر /ملغم ٤٠٦بالتتابع والتي تعطي انتاجية 375الحقيقية لالنتاج � في وسط االنتاج المثالي وغير s.marcescensالخطوة االخيرة من البحث تضمنت دراسة القوة الحركية لبكتريا .لتر /ملغم 12 ً ناتج دة الى ان البروجيوسين يعساعة باالضاف ٥٤لتر بعد /ملغم ٣٦٥٫٧النتائج ان اعلى انتاجية لصبغة المثالي وأظهرت . غير متعلق بالنمو ا introduction al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 8, no. 2, pp 77 83 (2012) extraction of penicillin v from simulated fermentation broth by liquid-liquid membrane technique khalid w. hameed department of biochemical engineering/al-khwarizmi college of engineering/university of baghdad email:kwhameed74@yahoo.com (received 25 december 2011; accepted 22 february 2012) abstract liquid-liquid membrane extraction technique, pertraction, using three types of solvents (methyl isobutyl ketone, nbutyl acetate, and n-amyl acetate) was used for recovery of penicillin v from simulated fermentation broth under various operating conditions of ph value (4-6) for feed and (6-8) for receiver phase, time (0-40 min), and agitation speed (300-500 rpm) in a batch laboratory unit system. the optimum conditions for extraction were at ph of 4 for feed, and 8 for receiver phase, rotation speed of 500 rpm, time of 40 min, and solvent of mibk as membrane, where more than 98% of penicillin was extracted. keywords: liquid-liquid membrane, penicillin v, pertraction, extraction. 1. introduction liquid-liquid membranes extraction technique combines extraction and stripping into one step, rather than the two separate steps required in conventional processes such as solvent extractions. a one-step liquid membrane process provides the maximum driving force for the separation of a targeted species, leading to the best clean-up and recovery of the species (1) . liquid membrane process, called also pertraction process, have gained increased attention due to its ambient temperature operation, relatively low capital cost, high separation efficiencies and modular construction. the process is inherently low-energy, continuous, and can be made highlyautomated. the amount of organic solvent required are generally very small, and thus the technology is environmentally benign (2, 3) . two aqueous solutions, feed solution f, and receiver solution r, are separated by a third, organic liquid m, representing the “liquid membrane” which is insoluble in the other two liquids. the solute is transferred from the feed to the acceptor solution under the effect of appropriately chosen equilibrium conditions at the two interface f/m and m/r. in liquid membranes, facilitated transport is the mass transfer mechanism for the target species to go from the feed solution to the receiver solution. (4, 5) . extraction using liquid membranes has been studied since the 1980s and is one of the most advantageous techniques of separation at the present. this separation method consists in the transfer of a solute between two aqueous phases of different ph which are separated by a solvent and carrier layer. the claimed advantages are as follows: the quantity of solvent used is small because of its continuous regeneration, the loss of solvent is small during extraction process provided the ph gradient between the two aqueous phases is maintained, there is a possibility of solute transport through liquid membranes that have been used for the separation of some biosynthetic products, namely carboxylic acids, amino acids and antibiotics (6, 7) .the membrane interposed between two miscible aqueous solution, at one side (feed phase) in which the solute to be transport is extracted, while at the other side (strip phase), re-extraction occurs. since in each of the aqueous phase some specific, and different for each of them, thermodynamic conditions exist, the extraction and re-extraction occur simultaneously (8, 9) . mailto:kwhameed74@yahoo.com khalid w. hameed al-khwarizmi engineering journal, vol. 8, no. 2, pp 7783 (2012) 78 the steps of transport of solute in the pertraction system are described as: diffusion through the boundary layer in the feed solution, sorption on the feed solution/liquid membrane interface, diffusion through boundary layer on the feed side, transport in the membrane, diffusion through boundary layer on the receiving side, desorption on the membrane/receiving solution interface and diffusion through the boundary layer in the receiving solution (10) . the incessant stripping of solute of the liquid membrane keeps low concentration of solute in this phase and therefore provides its complete recovery from the feed solution. one of the principal advantages of pertraction process is the practically complete removal of the valuable component from the source material using, in most cases, not sophisticated, friendly solvents, in particular-water. as far as the membrane liquid is considered, it is noteworthy to mention that the requirements to the liquid membrane are not the same as to the conventional solvents used in a solvent extraction process, because in pertraction, priority is given to the membrane selectivity, rather than to the capacity and the solute distribution coefficient (11) . penicillin v is a secondary metabolite produced at low growth rates and its syntheses have been described extensively in the literature. penicillin formation starts from three activated amino acids, and involves several enzymes and isopenicillin n as a major intermediate. penicillin v (phenoxymethylpenicillin) is the commercially most important penicillin. it is mainly converted to 6-aminopenicillanic acid (6-apa), which in turn is used to make amoxicillin and ampicillin. penicillin v is a weak acid and it is extracted with n-butyl acetate at ph 2-3. in this ph range penicillin v is unstable and decomposes, therefore the aqueous medium in fermentation broth is cooled to 0 o c and extracted in centrifugal extractor to keep contact time as short as possible (12) . in the present work the fermentation broth was simulated by dissolving penicillin v sodium salt in distilled water. liquid-liquid pertraction technique was conducted for the recovery of penicillin v in a batch pertraction laboratory unit. methyl isobutyl ketone (mibk), n-amyl acetate, and n-butyl acetate were proposed as membranes for penicillin v pertaction at 25 o c. the effect of speed of agitation, time, and ph were studied. 2. experimental work 2.1. material feed phase (donor phase): the feed phase was prepared by dissolving 1 g of penicillin v sodium salt in 1 l of distilled water, the ph of solution is adjusted by [4% h2so4 (bdh)] and [5% na2co3 (bdh)] (6) . receiver phase (stripping phase): a sodium carbonate solution was used as a receiver phase. membrane phase: in the present study, methyl isobutyl ketone (bdh), n-amyl acetate (bdh), and n-butyl acetate (bdh) were used as liquid membrane. 2.2. pertraction lab unit pertraction experiments were carried out in 1 liter laboratory pertractor as shown in fig. 1. the pertractor consists of two coaxial pyrex beakers and baffles where placed in each beaker as shown in fig. 1. the outer beaker is 1 liter and the inner is 250 ml. the two beakers were arranged as shown in fig. 1 and placed on a magnetic stirrer with heater in order to control the temperature and the speed. the membrane, feed, and receiver phases were stirred by using two teflon-coated magnetic bars. 2.3. experimental setup 500 ml of feed phase was placed in the annular space between the two beakers, and 200 ml of receiver phase was placed in the inner beaker. after that 300 ml of membrane phase was added to cover the other two phases as shown in fig.1. the outer beaker was covered with a thin plastic layer to prevent evaporation of membrane phase. in the present study the effect of speed of agitation using the three proposed membranes was studied in the range of 300-500 rpm. the speed of agitation and temperature were adjusted and controlled by using hotplate and magnetic stirrer. the pertraction time was continuing up to 40 min and during this period of time samples were taken at a specified time interval from the feed and receiver phases for penicillin v analysis by hplc. hplc type shimadzu model lc20ad was used in this analysis using column 100 rp-18 (5 μm). the penicillin v in the membrane organic phase was evaluated by material balance. khalid w. hameed al-khwarizmi engineering journal, vol. 8, no. 2, pp 7783 (2012) 79 fig. 1.schematic diagram of pertraction laboratory unit. 3. results and discussion in the present work, the batch pertraction of penicillin v using the three proposed liquid membranes was studied, the agitation speed, and liquid membrane type was conducted in this work. the efficiency of penicillin v extracted, e, was calculated as follows: %100 ffo rr vc vc e …(1) where cr is the penicillin v concentration in the receiver phase, cfo is the initial concentration in the feed phase, vr is the volume of receiver phase, and vf is the volume of feed phase. 3.1. effect of ph figures 2 and 3 show the relationship between the penicillin transport from feed and to the receiver phases respectively with ph at different liquids membrane and at agitation speed of 400 rpm and time of extraction of 40 min. the range of ph for feed phase is taken between (4-6) and for receiver phase between (6-8) because the penicillin v is unstable and decomposes for ph < 4 and ph > 8 (13) . from figure 2, it can be seen that the extraction of penicillin v from feed is increasing with the decrease of ph value and also from figure 3 the extraction of penicillin v by the receiver is increasing by increasing of ph value because the over all mass transfer coefficient increases when the difference in the ph value between two phases is high as possible (14) . in the figure 2, it seems that the best value of ph for extraction of penicillin v from feed is 4 where about 98% of penicillin v is extracted by mibk, while from figure 3, the best value of ph for extraction of penicillin v by the receiver phase is 8 although the ph value of 7.5 has little effect on the extraction. 1 baffles 7 membrane-receiver interface 2 magnetic stirrer 8 membrane phase 3 magnetic bars 9 receiver phase 4 membrane-feed interface 10 feed phase 5 feed-baker 11 plastic cover 6 receiver baker 2 4 5 7 6 8 1 1 3 9 10 11 khalid w. hameed al-khwarizmi engineering journal, vol. 8, no. 2, pp 7783 (2012) 80 fig. 2. ph effect on penicillin extraction from feed phase after 40 min and agitation speed of 400 rpm. fig. 3. ph effect on penicillin extraction by stripping phase after 40 min and agitation speed of 400 rpm. 3.2. effect of membrane type from figures 2 and 3, it can be seen that is a better solvent as a membrane and it can give better extraction efficiency methyl isobutyl ketone (mibk) with respect to other solvents (n-amyl acetate and n-butyl acetate). the extraction efficiency of penicillin v is evaluated by using equation 1 for three types of membranes at temperature of 25 o c, rotation speed of 400 rpm and ph for feed 4 and for receiver phase 8 as shown in table 1, where the difference in extraction efficiency for three types of membrane are very little; i.e., the effect of membrane type on extraction is little. table 1, extraction efficiency, e, of penicillin v for 3 types of membrane at 25 o c, 400 rpm and ph of feed 4 and of receiver 8. membrane type e mibk 90.8 n-amyl acetate 90 n-butyl acetate 89.6 figure 4 shows the penicillin v content in the feed (rf = fo f c c ), membrane, mibk, (rm = fo m c c ) and receiver phases (rr = fo r c c ) during the extraction at temperature of 25 o c, agitation speed of 400 rpm and ph of 4 for feed and 8 for receiver phases. it seems that about 80% of penicillin v is extracted during 15 min; i.e., the extraction process during this time is fast, while after 30 min the extraction is stable and there is no effect of time on extraction. fig. 4. penicillin v content in feed, membrane (mibk), and receiver phases with time at 25 o c and 400 rpm . ph c o n c e n tr a ti o n g /l 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.10 3.5 4.0 4.5 5.0 5.5 6.0 6.5 mibk amyl acetate butyl acetat time (min) r ( -) 0.0 0.2 0.4 0.6 0.8 1.0 0 5 10 15 20 25 30 35 40 45 50 feed ph=4 membrane receiv er ph=8 ph c o n c e n tr a ti o n g /l 2.02 2.06 2.10 2.14 2.18 2.22 2.26 2.30 5.5 6.0 6.5 7.0 7.5 8.0 8.5 n-butyl acetate n-amyl acetate mibk khalid w. hameed al-khwarizmi engineering journal, vol. 8, no. 2, pp 7783 (2012) 81 3.2. effect of agitation speed figure 5 shows the effect of speed of agitation on the extraction efficiency, e. in order to explore the effects of stirring rate, the extraction experiment were carried out at three different stirring rates, 300, 400, and 500 rpm. e value increases with increasing speed of agitation, which means that the extraction efficiency of penicillin v from feed phase to the receiver phase through liquid membrane improved with increasing the speed of agitation; this is because the higher stirring rate leads to much severer mixing between the aqueous solution and organic phase, which could accelerate the transport of penicillin v and enhance the mass transfer area between the aqueous solution and liquid membrane solution and reduce the mass transfer resistances of penicillin v from feed to liquid membrane in the extraction process, and from liquid membrane to the receiver phase in the stripping process. this variation in the efficiency indicates a diffusion control of the extraction process. according to previously published literature, although the mass transfer improved with higher speed of agitation, it was not applied because of increased risk of droplet formation which causes phase intermixing and deterioration of the process (10) . fig. 5. effect of rotation speed on the extraction efficiency using mibk as membrane, at 25 o c, and ph of 4 for feed and 8 for receiver phases. 4. conclusion the liquid-liquid membrane extraction, pertraction, of biosynthetic products constitutes advantageous alternatives to conventional separation methods because it reduces the number of stages required for an efficient separation and, therefore, for the corresponding energy and material consumption. it can be concluded that the separation of penicillin v from simulated broth could be enhanced by decreasing the ph value for feed up to 4 and increasing ph value up to 8 for receiver phase and increasing rotation speed up to 500 rpm. the type of solvent as a membrane has little effect on the extraction efficiency. 5. reference [1] james n. parker, m.d. and philip m. parker, penicillin, 2004, “a medical dictionary, bibliography”, and annotation research guide to internet references, copyright by icon group international, inc. [2] bradley d. smith et al, 1998, “facilitated of transport of carbohydrates, catecholamines, and amino acids though liquid and plasticized organic membranes”, journal of inclusion phenomena and molecular recognition in chemistry 32: 121-131. [3] mona m. naima, abir a. monir, 2002, “desalination using supported liquid membranes”, desalination 153, 361–369. [4] norman n. li, anthony g. fane,w. s. winston ho, and t. matsuura, 2008, “advance membrane technology and application”, john wiley & sons. [5] anil k. pabby, syed s. h. rizvi, ana maria sastre, 2009, “handbook of membrane separation”, taylor & francis group. [6] cascavala d., oniscua c., cascavalb c., 2000, “selective separation of penicillin v from phenoxyacetic acid using liquid membranes” , biochemical engineering journal 5, 45-50. [7] zainuddin abdul manan, mohamed mahmoud nasef, and siti hamidah mohd, 2007, “advances in separation process”, first edition. [8] richard w. baker, 2004, “membrane technology and applications”, john willy and sons. 2nd ed. [9] kamniski w., 2000, "applicability of liquid membrane in the environmental protection", rpm 85 86 87 88 89 90 91 92 93 94 95 280 320 360 400 440 480 520 e rpm khalid w. hameed al-khwarizmi engineering journal, vol. 8, no. 2, pp 7783 (2012) 82 polish journal of environmental studies vol. 9, no. 1, 37-43. [10] boyadzhiev l., k. dimitrov, d. metcheva, 2006, "integration of solvent extraction and liquid membrane separation: an efficient tool for recovery of bio-active substances from botantial", elsevier 20 march. [11] nabil n. ahmed al-hadithi, 2007, “determination of drug and metabolites in the water by use of liquid membrane systems and hplc-method development and application” m.sc. in chemistry, alanbar-iraq. [12] elmar heinzle, arno p. biwer, and charles l. coony, 2006, “development of sustainable bioprocesses modeling and assessment”, copyright john wiley & sons ltd. [13] benedict, rg., schmidt, wh., coghill, rd., oleson, ap.(1945) “the stability of penicillin in aqueous solution”, j. bact. 49: 85-95. [14] kheirolomoon a., sayfkordi a. a., kazemi-vaysari a., ardjmand m., and baradar-khoshfetrat a. july 2001, “mass transfer analysis of penicillin extraction”, scientia iranica vol. 8, no. 3 pp 179-184. (2012 )77 83 ، صفحة2، العذد 8 مجلة الخىارزمي الهنذسية المجلذخالذ وليذ حميذ 83 من ناتج التخمير المصطنع بأستخذام تقنية الغشاء السائل v استخالص البنسلين خالذ وليذ حميذ جاهؼت بغذاد / كل٘ت الٌِذست الخْاسصهٖ/ قسن الٌِذست الك٘و٘ائ٘ت االح٘ائ٘ت kwhameed74@yahoo.com :البشٗذ االلكخشًّٖ الخالصة اٗضّبْ٘حاٗل هثل ك٘خْى، اس٘خاث البْ٘حاٗل األػخ٘ادٕ، اس٘خاث )حن اسخخذام حقٌ٘ت األسخخالص بطشٗقت الغشاء السائل لثالد اًْاع هي الوزٗباث الؼضْٗت ( 6-4) هي ًاحج الخخو٘ش الوصطٌغ ححج ظشّف حشغ٘ل هخباٌٗت هي اط ُ٘ذسّجٌٖ٘ بوذٓ vّالخٖ أسخخذهج لغشض اسخخالص البٌس٘ل٘ي (األهاٗل األػخ٘ادٕ . فٖ هٌظْهت هخخبشٗت راث الٌظام الذفؼٖ (دق٘قت/ دّسة500-300)، ّسشػت خلط بوذٓ ( دق٘قت40-0)للطْس الوسخلن، صهي اسخخالص بوذٓ (8-6)للق٘ن ّ دق٘قت ّللوزٗب 40دق٘قت، صهي اسخخالص / دّسة500 للطْس الوسخلن، سشػت خلط 8 للق٘ن ّ 4الظشّف الوثلٔ لألسخخالص كاًج ػٌذ اط ُ٘ذسّجٌٖ٘ . هي البٌسل٘ي حن اسخخالصَ ضوي ُزٍ الظشّف% 98الؼضْٕ اٗضّبْ٘حاٗل هثل ك٘خْى، ح٘ذ اكثش هي mailto:kwhameed74@yahoo.com������ mailto:kwhameed74@yahoo.com������ 54-60 al-khwarizmi engineering journal,vol. 11, no. laser peening on aluminum alloy 7 alalkawi h. j. m. * *departement of **, *** college of (received abstract black paint laser peening (bplp) technique is currently applied for many engineering materials , especially for aluminum alloys due to high improvement in fatigue life and strength . constant and variable bending fatigue tests have been performed at rt and stress ratio r= surface work hardening which generated high negative improvement factor (flif) for bplp constant fatigue behavior was from 2.543 to 3.3 compared to and the increase in fatigue strength at 10 1.786 at l-h and 1.55 at h-l due to black paint coating . keywords: constant and variable fatigue behavior , black paint laser peening , 7049 al 1. introduction the failure of metalic material structure especially the light structures ( aluminum alloys ) is totally difficult to control , experimentally when the qpplied loads behaver in variable manner[1]. the estimation of the fatigue life companents subjected to random loading (cumulative amplitude conditions) subject [2]. however, in practice ma or components are subjected to complex fatigue loading which is happened due to changing in the applied stress amplitude. field of variable amplitude loading, it is an important to assess the fatigue damage due to variable amplitude loading conditions [3]. damage increases when cyclic stresses increase a cumulative way which may lead to fracture. fatigue damage analysis in variable loading very important factor in the fatigue of structures and components[4]. khwarizmi engineering journal,vol. 11, no. 3, p.p. 54-60 (2015) aluminum alloy 7 049 using black paint surface coating * basim a. sadkhan** noor n. electromechanical engineering/ university of technology college of engineering/ university of almustansiriyah. *email: alalkawi2012@yahoo.com **email: drbasimajel@yahoo.com ***email: nawara_najm@yahoo.com (received 9 september 2014; accepted 7 may 2015) black paint laser peening (bplp) technique is currently applied for many engineering materials , especially for aluminum alloys due to high improvement in fatigue life and strength . constant and variable bending fatigue tests nd stress ratio r= -1 . the results of the present work observed which generated high negative residual stresses in bplp specimens .the fatigue life improvement factor (flif) for bplp constant fatigue behavior was from 2.543 to 3.3 compared to and the increase in fatigue strength at 107 cycle was 21% . the bplp cumulative fatigue life behavior was l due to black paint coating . constant and variable fatigue behavior , black paint laser peening , 7049 alalloy . the failure of metalic material structure especially the light structures ( aluminum alloys ) difficult to control , experimentally when the qpplied loads behaver in variable manner[1]. of the fatigue lifetime of companents subjected to random loading is a complex in practice many structural are subjected to combined or happened due to stress amplitude. in the field of variable amplitude loading, it is an fatigue damage occurred conditions [3]. when cyclic stresses increase in which may lead to fracture. in variable loading plays life evaluation laser peening (lp) is which works to create stresses at the surface and to extend metal surface [5]. lp has been effective in improving the properties of many metals and alloys combination of laser and shot peening treatment was investigated in 7075 aa gave an optimum residual stress profile at the surface resulting in the improvement in fatigue life and strength of 7075 aa[7]. everett et al [ and 2024-t3 aa under fatigue tests using shot peening and laser peening treatments.the experimental results showed that after peening the fatigue life and crack growth rates were noticeably improv life was increase by a factor of 2 than the results of the average un pe .comparision between laser peening (lp) and shot peening (sp) residual stresses of 7049 made by rankin et al [ residual stress 0.1 mm from the surface due to lp al-khwarizmi engineering journal (2015) 49 using black paint surface noor n. abed*** f technology. black paint laser peening (bplp) technique is currently applied for many engineering materials , especially for aluminum alloys due to high improvement in fatigue life and strength . constant and variable bending fatigue tests that the significance of the bplp specimens .the fatigue life improvement factor (flif) for bplp constant fatigue behavior was from 2.543 to 3.3 compared to untreated fatigue cycle was 21% . the bplp cumulative fatigue life behavior was improved by alloy . p) is a surface treatment which works to create compressive residual surface and to extend below the p has been known to be very effective in improving the mechanical and fatigue many metals and alloys [6] .the combination of laser and shot peening treatment investigated in 7075 aa gave an optimum residual stress profile at the surface resulting in the improvement in fatigue life and strength of everett et al [8] examined4340 steel under fatigue and crack growth tests using shot peening and laser peening treatments.the experimental results showed that after peening the fatigue life and crack growth rates were noticeably improved and the fatigue life was increase by a factor of 2-4 times greater than the results of the average un peened results laser peening (lp) and shot peening (sp) residual stresses of 7049-t3 aa was made by rankin et al [9] .they observed that residual stress 0.1 mm from the surface due to lp alalkawi h. j. m al-khwarizmi engineering journal, vol. 11, no. 3, p.p. 5460(2015) 55 was far greater than for sp. aa type ly2 was tested under lp in two ways and they compared .the results show that the lp improved the fatigue life by 131.4 % compared to untreated condition [10]. laser peening treatment without protective coating (lpwc) was carried out by yasuo ochi et al[11] to improve fatigue strength ,the result showed the lpwc treatment was effective for the fatigue strength improvement in fatigue lives regime before 2∼3×106 cycles, but the treatment reduced the strength after the cycles at the both stress ratios conditions. duplex stainless steel alloy used to study the effect of laser treatment on fatigue charistrestice . the condaded remarks were increasing pulse density reducing the growth of the cracks which resulting in increasing the fatigue life[12]. different laser peening were used to study the laser effect on lifetime of (3003-h18) aa using different (lp). the results observed that the fatigue lifetime increment over the life of samples without (lsp) in range (12%) for 1-spot lsp, 18%for 2-spots lsp and 77%for 3-spots lsp[13]. al-6061-t6 surface topography was studied using energy nd: yag laser with 300mj. they concluded that laser peening without coating (lpwc) can significantly improve the surface topography i-e compressive stress , and microhardness but the surface roughness showed an increase. the compressive residual stress was improved by 27% and the hardness was increased by 10 hv [14].45 specimens of 7049 aa were examined under constant rotating fatigue at r= -1 using 7049 aa to establish the s-n curve for three types of surface coatings .15 specimens for air without peening ,15 specimens for air laser peening (alp) and the third group 15specimens was tested under water laser peening (wlp). the results indicated that no effect of laser peening at low cycle fatigue ( lcf ) above 300 mpa . but this effect appeared clearly at (hcf). also it was concluded that the fatigue life improvement factor is 32.6 and 8.97 under wlp for 200mpa and 250 mpa respectively[15]. date in the literture observed the benficial effects on fatigue life , an increase in fatigue life by as much as a factor of 10 at a given stress level for aluminum alloys[16] . 2. experimental details 2.1. material and testing the material used was 7049 aa supplied as a round bar of 10mm diameter with chemical composition in weight percentage as given in table (1). the mechanical properties of the material were obtained using an instron machine . the average results of three tests are presented in table (2). table1, chemical composition in wt% of 7049 aa. element si% fe % cu% mn % mg% cr% zn% ti% al% standard max. 0.25 max. 0.35 1.2-1.9 max. 0.2 2-2.9 0.1-0.22 7.2-8.2 max. 0.1 bal. experimental 0.21 0.29 1.52 0.14 2.5 0.18 7.8 0.08 bal. table 2, mechanical properties of 7049 aa. property yield stress, �� (mpa) ultimate stress, �� (mpa) elongation% modulus of elasticity, ϻ e (gpa) hb experimental 312 515 19 74 0.32 131 standard 317 520 20 74 0.33 135 alalkawi h. j. m 2.2. fatigue specimen fatigue specimen , shown in figure(1) employed to carryout all the fatigue tests laser peening and without laser treatment . fatigue specimens were manufactured using programmable (cnc) turning machine specimen is: fig. 1. fatigue specimen dimensions ( (all dimnsions in mm). the detailed dimnsions of specimen are shown in fig. (1) . the samples were then numbered and grinded , first , with grades 200,400,600,1000,1200 emery paper. after grinding , one sample was polished firstly using polishing cloth with diamond pastes with 1/3 micron,for 5 minutes and then etched in keller solution for a 2-3 minutes . 2.3. fatigue test procedure fatigue analysis are normally based on the results obtained from s-n curve then the first step was to established the constant continuous cycling s-n curve .fifteen specimens were tested under room temperature control stress with zero mean stress .the second step was to find the s with black paint laser peening (bplp) in order to do a comparison in life and strength . the third group of testing was 12 specimens , 6 specimens under untreated cumulative fatigue and the other 6 specimens under (bplp) cumulative fatigue . 2.4. fatigue test rig. a fatigue test machine of type (sc punn rotating bending is employed the fatigue test, as illustrated in figure (4): al-khwarizmi engineering journal, vol. 11, no. 56 shown in figure(1) , was employed to carryout all the fatigue tests under laser peening and without laser treatment .all the fatigue specimens were manufactured using machine ,the test (din 50113) nsions of specimen are shown were then numbered and grinded , first , with grades 200,400,600,1000,1200 emery paper. after polished firstly using with diamond pastes and alumina for 5 minutes and then etched in fatigue analysis are normally based on the curve then the first step was to established the constant continuous cycling specimens were tested under room temperature control stress with zero mean stress .the second step was to find the s-n curve plp) in order to do a comparison in life and strength . the third specimens , 6 specimens cumulative fatigue and the other 6 specimens under (bplp) cumulative fatigue . f type (schenck) punn rotating bending is employed to execute fatigue test, as illustrated in figure (4): cycles counter specimen motor load fig. 2. fatigue test machine. 2.5. laser surface treatment the laser system used in this work was (q switched nd–yag laser) with wavelength is about 1.065 µm ,the energy ns) shock with black paint for each specimen around the minimum diameter of fatigue specimens were selected. figure (2) shows (q-switched nd system ) used in the present study . fig. 3. nd–yag laser peening device of technology-baghdad . fig (4) illustrates the laser ring around the minimum diameter. laser spots fig. 4. laser spots around min. diameter of fatigue specimen. khwarizmi engineering journal, vol. 11, no. 3, p.p. 5460(2015) specimen load switch . fatigue test machine. surface treatment the laser system used in this work was (qyag laser) with wavelength is m ,the energy of pluse (300)mj . (16 shock with black paint for each specimen around the minimum diameter of fatigue switched nd –yag laser system ) used in the present study . laser peening device at university ig (4) illustrates the laser ring around the 4. laser spots around min. diameter of fatigue min dia. of shaft of shift alalkawi h. j. m al-khwarizmi engineering journal, vol. 11, no. 3, p.p. 5460(2015) 57 3. results and discussion table (3) gives the results of the three groups mentioned above . table 3, constant and variable fatigue tests with and without (bplp). condition dry fatigue s-n curve results specimens no. applied stress (σƒ)( mpa ) cycles to failure nƒ (cycles) nƒ average 1,2,3 400 2000,2200,2500 2233 4,5,6 300 6000,7000,8000 7000 7,8,9 250 33000,31800,32600 32467 10,11,12 200 63000,57500,66000 62167 13,14,15 150 642000,664300,686600 664300 bplp fatigue s-n curve results 16,17,18 400 4200,5000,3800 4333 19,20,21 300 9000,11200,10000 10067 22,23,24 250 119000,130000,110000 119667 25,26,27 200 205000,198000,180000 194333 28,29,30 150 2479000,2655000,2303000 2479000 dry cumulative fatigue results l-h 31,32,33 200-300 12700,16000,11600 13433 h-l 34,35,36 300-200 10800,11600,14000 12133 bplp cumulative fatigue results l-h 37,38,39 200-300 27000,20000,25000 24000 h-l 40,41,42 300-200 21000,18600,17000 18867 3.1. basic s-n curve fig (5) describes the results obtained from constant stress amplitude tests at room temperature under stress control condition and zero mean stress with and without bplp . the bending stress was calculated from the bending moment using the equation : σb(n/mm2 ) = 125.7*32*p(n) / π d³ ...(1) where p is the applied load (n) and the arm of the force is equal to (125.7mm) and d is the minimum diameter of the specimen in mm . fig. (5) illustrates the effect on the fatigue lifetimes of specimns that have been pened under (bplp) . as shown by the experimental date , the fatigue life of (bplp) specimens is improved compared to unpeened specimens and this improvement can be described by table (4) below for different stress levels . the bplp creates compressive residual stresses, there by ofering improved resistance to the growth of nearsurface , macroscopic crack . this characteristic can , therefore , lead to signficant improvements in the fatigue life of treated specimens , which leads to high flef given in the above table . this finding is in good agreement with ref [11 ]. table 4, fatigue life improvement factor due to bplp for different stress levels. fatigue life improvement factor (flif) 0.4 σu 0.5 σu 0.6 σu 0.7 σu 0.8 σu 208 mpa 260 mpa 312 mpa 364 mpa 416 mpa 3.3 3.03 2.833 2.674 2.543 alalkawi h. j. m al-khwarizmi engineering journal, vol. 11, no. 3, p.p. 5460(2015) 58 fig. 5. convential basic line s-n curve for untreated and bplp fatigue . the stress amplitude and life (nƒ) were estimated from the relation known as the basques equation , gives the fatigue strength properties and may take the following formula. σƒ = a(nƒ) α ...(2) where a : is the fatigue strength coefficient. α : is the fatigue strength exponent. the value of the parameters in equation (2) are listed in table (5) table 5 fatigue properties of 7049 aa. α a condition -0.145 981 untreated fatigue -0.135 1064 bplp fatigue the bending fatigue properties of 7049 aa that has received bplp and untreated , respectively are compared in fig (5) . the bplp gave a 21% rise in endurance fatigue limit, compared with the untreated specimens . peyre et al [14] have found that an increase of 22% in fatigue strength of 7075-t7351 aa after treating by lsp ( 3.8 g w/cm2 ) compared to the unpeened specimens . the constant fatigue life of 7049 aa are improved, as illustrated in table (4), based on stress level applied . this improvement treated due to greater plastiaty affected depth in the matrials as well as the preservation of surface roughness . clauer etal [17]concluded that the constant fatigue life of 2024 –t3 specimens with solid laser spot has a fatigue life about 40 times longer than the annular laser spot and a life about three times greater than the as-recived ones . referring to table (3). it can be obtained a cumulative fatigue life improvement factor (cflif) for cumulative fatigue results in table (6). table 6, cumulative constant fatigue life improvement factor . stress sequences mpa cumulative fatigue life improvement factor ( cflif ) 200-300 1.786 300-200 1.555 it can be seen that : the cumulative fatigue life was increased by a factor of 1.786 at low –high stress sequences while this factor reduced to 1.555 at high –low stress sequences . the fatigue life of 7049 was extended by bplp due to greating compressive stress at the surface. this finding is in good agreement with peyre etal [14] . 4. conclusions the bending fatigue behaviour of 7049 alalloy were stuided , the following remarks are drawn from the work described here in : 1the fatigue strength at 107 cycles was improved by a 21% increase due to bplp . 2the fatigue life improvement factor ( flif) was obtained to be from 2.543 to 3.3 due to bplp based on stress level applied . 3the lives of sequence loading (l-h) were higher than lives of sequence loading (h-l) either with bplp or without . 4the fatigue lives were improved by afactor of 1.786 at ( l-h ) , while this factor was 1.555 at ( h-l ) due to bplp . σƒ = 1064n ƒ -0.135 for bplp σƒ = 981n ƒ -0.145 untreated fatigue 100 150 200 250 300 350 400 450 0 500000 1000000 1500000 2000000 2500000 3000000 a p p li e d s tr e ss (m p a ) number of cycle to failure \ alalkawi h. j. m al-khwarizmi engineering journal, vol. 11, no. 3, p.p. 5460(2015) 59 notation aa aluminum alloy bplp black paint laser peening cflif cumulative fatigue life improvement factor flif fatigue life improvement factor hcf high cycle fatigue h-l high-low stresses lcf low cycle fatigue l-h low-high stresses lpwc laser peening without coating lp laser peening r stress ratio sp shot peening 5. references [1] pavlou, d.g., a phenomenological fatigue damage accumulation rule based on hardness increasing, for the 2024-t42 aluminum, engineering structures, 2002, vol. 24 , pp. 1363-1368. [2] franke, l. and dierkes, g., a non-linear fatigue damage rule with an exponent based on a crack growth boundary condition, international journal of fatigue, 1999, vol. 21, pp. 761-767. [3] kawai, m., and hachinole, a., two-stress level fatigue of unidiretional fiber-metal hybrid composite: glare 2, international journal of fatigue, 2002, vol. 24, pp. 567580. [4] fatemi, a. and yang, l., cumulative fatigue damage an life prediction theories: a survey of the state of the art for homogeneous materials, international journal of fatigue, 1997, vol. 20, no. 1, pp. 9-34. [5] hu, y., yao, z., hu, j.: 3-d fem simulation of laser shock processing. in: surface & coatings technology 201 (2006), p. 14261435. [6] rubio-gonzalez, c., ocana, j.l.,gomezrosas, g., et al.: effect of laser shock processing on fatigue crack growth and fracture toughness of 6061-t6 aluminum alloy. in: materials science and engineering a386 (2004), p. 291-295. [7] p.peyre , r.fabbro ,p.merrien , h.p.lieurade , et al. :laser shock processing of aluminum alloys,application to high cycle fatigue behavior . in matrial science and engineering a210 ,pp102-113 (1996). [8] everett r.a. , w.t.matthews , et al. : the effects of shot and laser peening on fatigue life and crack growth in 2024 aluminum alloy and 4340 steel . in nasa/tm-2001210843 ,arl – tr-2363 (2001) . [9] rankin j.e , michael r.h , lloyd a.h. et al. : the effects of process variations on residual stress in laser peened 7049-t73 aluminum alloy materials science and engineering pp279-291 (2003). [10] zhang, y.k., lu, j.z., ren, x.d., et al.: effect of laser shock processing on the mechanical properties and fatigue lives of the turbojet engine blades manufactured by ly2 aluminum alloy. in: materials and design 30 (2009), p. 1697-1703. [11] yasuo ochi , takashi matsumura , kiyotaka masaki , toshifumi kakiuchi , yuji sano , takafumi adachi, et al. : effect of laser peening treatment without protective coating on axial fatigue property of aluminum alloy. inscience direct 2 ,pp491-498(2010). [12] rubio-gonzales, c., felix-martinez, c., gomez-rosas, g., et al.: effect of laser shock processing on fatigue crack growth of duplex stainless steel. in: materials science and engineering a 528 (2011), p. 914-919. [13] alalkawi h.j., abdul-jabar h.ali, saisaban a.fahad ,et al. :effect of laser shockpeening on fatigue life of aluminumalloy (3003-h18). in: mechanical engineering 61(2013), p. 17107-17109 . [14] s.sathyajith , s.kalainathan , s.swaroop , et al. :laser peening without coating on aluminum alloy al-6061-t6 using low energy nd:yag laser )) optics and laser technology 45,pp 389-394(2013). [15] alalkaw h.j. , bedaiwi b.a. ,adel a.m. et al. : constant fatigue behavior under different conditions of laser peening proceeding of the asme 2014 . international mechanical congress and exposition (imece ) , montereal , canada 14-20 november 2014 . [16] berns h. , weber , et al. : influence of residual stresses on crack growth .in impact surface treatment , pp 33-44 (1984). [17] [17] clauer a.h., dulaney r.c., rice r.c. , koucky j.r. , et al. : laser shock processing for treating fastener holes in aging aircraft . durability of metal aircraft structure , in processing of the international workshop on structure integrity of agingaircraft , pp350-361 (1992). ا������� � ���ن ���م ا�����وي �� 2015( 5460، ��� 3، ا�� د11 ا���ارز�� ا���( 60 ا������م � ام ا�*,ء ا���د �� *�ح ٧٠٤٩ا�$�# ا���"ري � ���-�./ 6.ن* 4 �3 2.�1 ا����.وي� 1 72.8�./ ** ***�9ر 8 1�9� ���� ��� ھ���� * ����'� ا"&��%"%$��/ ا"�! و� ا") �'� ا"+�&�/ .�/ -,�� ا"!���� / ��� ھ���� ا"+%اد *** ،**� ا") alalkawi2012@yahoo.com 0و� &�:ا"2 .� ا1" * drbasimajel@yahoo.com 0و� &�:ا"2 .� ا1" ** nawara_najm@yahoo.com : 0و� &� ***ا"2 .� ا1" ا��,� �4 ا"+%اد ا"!����� وان �5�2��d ا1"+��%م =�c2 ا�!� a,? b+'8 8@��4 ا?+�ر ��1+�8<��� ا"&/,�� =�",�>ر �: ا�&�7ام ا"/92 ا�1%د �8&�7م "� �و�� ا"�fل >��=&� و�&�h ة ا"�'� ?�� در$� j ارة ا"�g h و���2 ا$!�د . وk l�d��ت ا"�fل ا�1@�n%@g ز��qd ھpا ا"'+�8)r=-1 . 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"'��k لf��b 8@��4 ?+ ا"�?)flif( 4� u���"/92 ا�1%د -= ��,s+"ت ا���',"٢.٥٤٣ a"ل ٣.٣اf��ر�� �: ا">��"qا"]� '+ ���و>� 0g دة�و?+,�� ا"fsء =�"/92 ا�1%د وا",�>ر ادت ا"a ز. �% . ٢١دورة =���2 ١٠٧ا"�fل ?�� ��ن ا"&/,�� =�",�>ر �: ا"fsء =�"/92 ا�1%د ادت ا"�h ( 0g 4�@8 a ة ا"�'� &�( �,%ك ا?+�ر ا"�fل ا"& ا-+0 اg �"�� ) l(?�� ا$1!�دات �4 واط�c ١.٧٨٦ا1?+�ر =+<�ار ? a"ا)h ( ء ١.٥٥وfs"ا :��4 ا$1!�دات ا"'�"�� ا"a ا"%اط�c �&�)� ا"&/,�� =�",�>ر 2/"� . 9 ا�1%د= ريم جلال 1 al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 8 , no. 3 , pp 63 -74 (2012) studying the probability of using groundwater in baghdad city for human, animal, and irrigation use reem j. channo department of biomedical engineering/ al-khwarizmi college of engineering/ university of baghdad email: reem_jchanno@yahoo.com (received 20 september 2011; accepted 28 may 2012) abstract groundwater is an important source of fresh water especially in countries having a decrease in or no surface water; therefore itis essential to assess the quality of groundwater and find the possibility of its use in different purposes (domestic; agricultural; animal; and other purposes). in this paper samples from 66 wells lying in different places in baghdad city were used to determine 13 water parameters, to find the quality of groundwater and evaluate the possibility of using it for human, animal and irrigation by calculating wqi, sar, rsc and na% and tds indicators. wqi results showed that the groundwater in all wells are not qualified for human use, while sar and rsc indicated that most samples are suitable for irrigation use, and tds showed that 74% of samples are suitable for animal use especially for sheep and meat-livestock animals. keywords: groundwater quality, wqi, sar, rsc, na%. 1. introduction ground water originates as infiltration from precipitation, 40 percent of the precipitation falling on the earth’s land masses does not evaporate, but collects on the surface, flows into streams and rivers and empties into the oceans, while some seeps into the soil to become underground water that slowly moves toward the seas [1, 2, 3]. almost all of the world water (97 %) is located in the oceans, but the high concentration of salts renders the ocean virtually unusable as source of water for municipal; agricultural or most industrial needs, 2% of water is in the form of ice caps and glaciers. only 1% is available as fresh water which is the main source of water for human consumption and other uses. this 1% is available as fresh water lakes, rivers, and streams which account 0.0072 percent of the world’s stock of water, while ground water accounts 1.7 percentage of world supply water [1, 3]. as population grows and development proceeds, rising demands for water increase the potential for internal disruption within countries and external conflict with other countries. many countries depend on local rivers for their water supply, but their upstream neighbors control the flow. iraq depends on about 66% of the surface water supply of rivers while its neighbors control almost all of the rivers total flow. some countries use ground water as a source of water supply, in usa about 50% of its population depend on ground water as a source of drinking water, with 30% delivered by community systems and 20% from domestic wells [1, 2]. quality of ground water is equally important to its quantity owing to the suitability of water for various purposes [4]. as other sources of water, ground water is threatened with pollution from different sources such as domestic wastes; industrial wastes; agricultural wastes; runoff from urban areas; soluble effluent; earthen septic tanks; leaching and downward movement of pollutants; waste water treatment lagoon [5, 6]. ground water chemistry, in turn, depends on a number of factors, such as general geology, degree of chemical weathering of various rock types, quality mailto:reem_jchanno@yahoo.com reem j. channo al-khwarizmi engineering journal, vol. 8, no.3, pp 63 -74 (2012) 64 of recharge water and inputs from sources other than water-rock interaction, such factors and their interaction result in a complex ground water quality [4], therefore monitoring and conserving this important resource is essential. the aim of this study is to show the possibility of using ground water of baghdad city for domestic, irrigation and animal purposes . 2. description of the study area raw water samples were taken from wells drilled in different places of baghdad city by the ministry of water resources of iraq. baghdad city lies 43m above see water level, 33º 19' 33" latitude and 44º 26' 19" longitude within the tigris river [7], with overall area of 4555 km2 (about 1.5% of iraq overall area), and a population of about 7.2 million people (about 24% of iraq population) [8]. fig.1 shows the locations of the wells in baghdad city (45 well in al-karkh side and 21 in al-rusafa) using artgis 9. fig.1. wells drilled in different places in baghdad city. reem j. channo al-khwarizmi engineering journal, vol. 8, no.3, pp 63 -74 (2012) 65 3. samples collection the data used in this paper were taken from 66 wells lying in different places in baghdad city from 33º10'00" to 33º30'00" in latitude and from 44º15'00" to 44º30'00" in longitude; and within 25m in depth by the ministry of water resources of iraq. one sample of ground water from each well was already analyzed physically and chemically and parameters of ec, ph, t.d.s, th, cl, co3, hco3, so4, no3, ca, mg, na and k were determined for the 66 samples by the same ministry. table 1 shows the max., min., average and standard deviation values of these parameters for the ground water samples. these data were taken and used to evaluate the probability of water use for human, animal and agriculture by calculating wqi (water quality index), sar (sodium adsorption ratio), rsc (residual sodium carbonate) and na% (sodium percentage) indicators. table 1, minimum, maximum, average and standard deviation values of physical and chemical parameters of ground water samples. parameter min. value max. value mean value sd. value ph 7.2 8.7 7.8 0.3788 ec 1100 29600 7179.8 5746.9 t.d.s 864 19064 4735.3 3672.8 th (as caco3) 696.4 10664 2337.7 3249.11 cl 107 8724 1477.5 1616.1 co3 0 70 7.6364 15.66 hco3 33 491 163.62 105.74 so4 40 3110 688.18 502.77 no3 0.1 17.5 2.3689 3.3617 ca 72 1100 407.65 252.11 mg 67 1924 542.21 449.96 na 101 6405 1386.8 1254.3 k 2 60 12.944 11.82 all parameters are in mg/l except ph has no unit and ec in μs/cm. 4. drinking water parameters thirteen water parameters were determined and compared with the iraqi drinking water standards and also using the who and us public health service drinking standard values if any absence in the iraqi standards as shown in table 2. table 2, water quality standard [6, 15]. parameters iraqi drinking standard ph 6.5 – 8.5 ec 1500 * tds 1000 th (as caco3) 500 ca 150 mg 100 na 200 k 12 * cl 350 co3 hco3 120 ** so4 400 no3 50 all parameter are in mg/l except ph has no unit and ec in μs/cm. * who standard [6]. ** us public health service value [6]. 4.1. ph ph values for the samples vary between 7.2 and 8.7 with a standard deviation of 0.3788. all of the samples were within the iraqi standard range except for one sample. ph usually has no direct impact on consumers, but it is one of the most important operational water quality parameters [9]. fig. 2 shows the cumulative percentage for no. of samples vs. ph values indicating that all of the samples are within the drinking standards. fig. 2. ph values vs. cumulative percentage of the samples. reem j. channo al-khwarizmi engineering journal, vol. 8, no.3, pp 63 -74 (2012) 66 4.2. chloride (cl) the maximum value of cl was 8724 mg/l and the minimum 107 mg/l with a standard deviation of 1616.1. no health-based guideline value is proposed for chloride in drinking water. however, chloride concentration in excess of about 250 mg/l gives water detectable or salty test which is objectable to many people [9, 10]. fig. 3. cl values vs. cumulative percentage of samples. in ground water the high concentration of chloride may be attributed to the presence of soluble chloride from rocks and saline intrusion [10]. also high chloride concentration may be an indication of pollution from sewage leakage. fig. 3 shows that 23% of samples are within the iraqi standard for drinking water which is 350 mg/l. 4.3. total hardness (th) hardness of water is defined as the inhabitation of soap action in water which is due to the precipitation of mg and ca salts [11, 14]. th is calculated from the formula [11]; th (caco3) mg/l = 2.497 ca + 4.115 mg …(1) th of water limits are used for industrial purposes, it causes scaling in pots and boilers, closure in pipes, and may cause health problems to human, such as kidney failure and some evidence indicates its role in heart diseases [6, 11]. however, no health-based guideline value is proposed for hardness, also the degree of hardness in water may affect its acceptability to the consumer in terms of taste and scale deposition [9]. iraqi standard proposed a value of 500 mg/l for drinking water standard [15], fig.4 shows that all the samples are out of the permissible limit. fig. 4. th values vs. cumulative percentage of samples. 4.4. sodium (na) sodium concentration ranged from 101 mg/l to 6405 mg/l with a standard deviation of 1254.3. as shown in fig. 5 only 9% of the samples are within the permissible limit. concentration in excess of 200 mg/l of na gives rise to unacceptable (salty) taste [9]. na salts are not actually toxic substances to human because of efficiency with which mature kidneys excrete na [10]. fig. 5. na values vs. cumulative percentage of samples. reem j. channo al-khwarizmi engineering journal, vol. 8, no.3, pp 63 -74 (2012) 67 sodium concentration is important in irrigation water but high concentration is an issue in irrigated areas when the ratio of soluble sodium to calcium and magnesium ions in water is high this can cause low permeability soil and become salty [14]. 4.5. sulfate (so4) the maximum concentration was 3110 mg/l and the minimum was 40 mg/l with standard deviation equal to 502.77, about 36% of the samples were within the iraqi standard [15] which is 400 mg/l as shown in fig. 6. studies with human volunteers indicate a laxative effect at sulfate concentration of 10001200 mg/l but no increase in diarrhea, dehydration or weight loss. the presence of sulfate in drinking water may also cause noticeable taste and may contribute to the corrosion of distribution systems [9]. fig. 6. so4 values vs. cumulative percentage of samples. 4.6. total dissolved solid (tds) the tds concentration ranged from 864 mg/l to 19064 mg/l with a standard deviation of 3672.8; all samples except one exceeded the permissible limit 1000 mg/l as shown in fig. 7. no health based guideline value is proposed. however, the presence of high levels of tds in drinking water may be objectionable to the consumer [9]. tds is a general indication of the amount of water salty and its originally and kind, knowing that the kind and concentration of dissolved salt in water depend on the environment of the study area, kind of existing rocks and velocity of ground water runoff [14]. fig. 7. tds values vs. cumulative percentage of samples. 4.7. electrical conductivity (ec) values of ec ranged from 1100 μs/cm to 29600 μs/cm with standard deviation equal to 5746.9, ec is an indication of the total dissolved salt content in water consequently it indicates the capacity of an electrical current that passes through the water, which in turn is related to the concentration of ionized substance present in it [10]. fig. 8 shows the cumulative percentage for no. of samples vs. ec values. fig. 8. ec values vs. cumulative percentage of samples. reem j. channo al-khwarizmi engineering journal, vol. 8, no.3, pp 63 -74 (2012) 68 the maximum limit of ec in drinking water is prescribed as 1500 μs/cm by who [6], the interpreted water quality with respect to ec indicates that 2 samples only lies in the good range for drinking water purposes. 4.8. bicarbonates and carbonate (hco3 & co3) bicarbonate and carbonate ions are the main resource for alkalinity in water which give an unpleasant taste to water. the main resource of bicarbonate ion ground water is from the infiltration water containing dissolved carbondioxide [14]. fig. 9. hco3 values vs. cumulative percentage of samples. fig. 10. co3 values vs. cumulative percentage of samples. fig. 9 shows that 42% of samples are within the permissible limit for hco3 which is 120 mg/l depending on us public health service value [6]. while fig.10 shows the cumulative percentage for no. of samples vs. co3 values 4.9. nitrate (no3) it is an important ion for agriculture that decreases the usage of nitrogen for fertilization but with excessive concentrations it becomes toxic to human [14]. the maximum value of no3 was 17.5 mg/l and the minimum was 0.1 mg/l with a standard deviation of 3.362 which is within the acceptable limit of 50 mg/l depending on the iraqi standard for drinking water [15]. as shown in fig. 11, all the samples are within the acceptable limits. fig. 11. no3 values vs. cumulative percentage of samples. 4.10. calcium (ca) calcium concentration of the tested samples ranged from 72 mg/l to 1100 mg/l with a standard deviation of 252.11, as shown in fig. 12, 12% of the samples were within the acceptable value of 150 mg/l (table 2) [15]. ca is presented in ground water as suspension where calcium bicarbonate is the prime cause for the hardness in water [10, 14]. excessive calcium in drinking water is linked to the formation of concretions in the body and may cause gastro intestinal diseases and stone formations [10]. reem j. channo al-khwarizmi engineering journal, vol. 8, no.3, pp 63 -74 (2012) 69 fig. 12. ca values vs. cumulative percentage of samples. 4.11. magnesium (mg) the concentration of mg ranged from 67 mg/l to 1924 mg/l with a standard deviation of 449.96, 91% of the samples (fig.13) exceeded the acceptable limit of 100 mg/l depending on the iraqi standard [15]. fig. 13. mg values vs. cumulative percentage of samples. 4.12. potassium (k) potassium concentration of the samples ranged from 2 mg/l to 60 mg/l with standard deviation 11.82. potassium is an essential element for plants and animals. the elements present in the plant material and are lost from agricultural soil by crop harvesting and removal as well as leaching and runoff on organic residues [10]. fig.14 shows that 64% of samples are within the acceptable range of 12 mg/l depending on who standard [6]. fig. 14. k values vs. cumulative percentage of samples. 5. results and discusion 5.1. water quality index (wqi) wqi is used to reduce the large amount of water quality parameters to a single numerical value [10]. the importance of various parameters depend on the intended use of water [12]; here, water quality parameters are used to evaluate the suitability of groundwater for human consumption. to calculate wqi the following steps were used [6, 10, 11, 12, 13]; 1. each of the 13 parameters (ec, ph, t.d.s, th, cl, co3, hco3, so4, no3, ca, mg, na and k) has been given an assigned weight (wi) according to its relative importance in the overall quality of water for drinking purposes as shown in table 3 ranging from 1 to 5. a maximum weight of 5 is given to the parameters so4, no3, cl, and tds for their importance in water quality assessment, while a minimum value of 1 is given to the parameters th, k, and co3 that play an insignificant role in the water quality assessment [11]. 2. second step is finding the relative weight depending on the following equation; …(1) reem j. channo al-khwarizmi engineering journal, vol. 8, no.3, pp 63 -74 (2012) 70 where wi = relative weight, wi = weight of each parameter, n = number of parameters. table 3, water quality standard, assigned and relative weight value needed to calculate water quality index. parameters drinking standard mg/l assigned weight wi relative weight wi ph 6.5 – 8.5 * 2 0.05 ec 1500 ** 3 0.075 tds 1000 5 0.125 th (as caco3) 500 1 0.025 ca 150 3 0.075 mg 100 3 0.075 na 200 4 0.1 k 12 1 0.025 cl 350 5 0.125 co3 1 0.025 hco3 120 2 0.05 so4 400 5 0.125 no3 50 5 0.125 * ph has no unit, ** ec in μs/cm. 3. third step is calculating the quality rating qi using the equation; …(2) except for ph where qi is calculated from the fallowing equation; …(3) where qi = quality rating, ci = concentration of each water parameter in mg/l, si = standard value for each water parameter. qi = 0 when pollutant is totally absent in the water sample and qi = 100 when the value of the parameter is just equal to its miscible value, thus the higher the value of qi is, the more polluted is the water [12, 13]. 4. last step is computing wqi using the following equation; …(4) where wqi = water quality index, qi = rating based on the concentration of ith parameter, wi = relative weight of ith parameter. in the end of the last step wqi is computed for each sample (for each well), it ranged from 51 to 1242 as shown in fig.15. according to the wqi the water can be classified as shown in table 4. from this table the water from these well are classified unsuitable for drinking purposes. table 4, wqi range and type of water classification [6]. range type of water < 50 excellent water 50 100 good water 100.1 200 poor water 200.1 – 300 very poor water > 300 water unsuitable for drinking purposes fig. 15. wqi values vs. cumulative percentage of samples. 5.2. water quality for irrigation purposes 5.2.1. sodium adsorption ratio (sar) sar and ec are used to evaluate water quality for irrigation. sar is a measure of alkali/sodium hazard to crops [4] and is calculated using the fallowing equation [4, 11]; …(5) all ionic concentration are expressed in meq/l. sar ranged from 1.16 to 28 (fig.16) and according to table 5, 56% of the samples were under the category of excellent water for irrigation reem j. channo al-khwarizmi engineering journal, vol. 8, no.3, pp 63 -74 (2012) 71 and 33% of samples were under the category of good water for irrigation. fig. 16. sar values vs. cumulative percentage of samples. table 5, classification of ground water for irrigation based on sar [4]. quality of water sodium adsorption ratio (sar) excellent < 10 good 10-18 doubtful 18-26 unsuitable >26 5.2.2. residual sodium carbonate (rsc) rsc is an indicator to the hazards effect of carbonate and bicarbonate on irrigation water, and is calculated using the formula [4, 11]; rsc = [(hco3 +co3) – (ca + mg)] …(6) where rsc and all ionic are expressed in meq/l. based on table 6, fig.17 shows that all samples are good for irrigation. table 6, classification of irrigation water based on rsc [15, 4]. quality of irrigation water residual sodium carbonate (rsc) in meq/l good < 1.25 unsuitable >2.5 fig. 17. rsc values vs. cumulative percentage of samples. 5.2.3. sodium percentage (na%) na reacts with soil to reduce its permeability and support little or no plant growth so it is considered vital for determining ground water suitability for irrigation and is usually expressed in terms of percentage sodium calculated using the formula [4]; …(7) fig. 18. na% values vs. cumulative percentage of samples. all ionic concentration are in meq/l, based on na% < 35 in ground water is suitable for irrigation purposes [4], with na% ranging from 18.43 to reem j. channo al-khwarizmi engineering journal, vol. 8, no.3, pp 63 -74 (2012) 72 85.67 (fig.18), only 14% of samples are suitable for irrigation purposes depending on na%. 5.3. water quality for animal use tables 7 and 8 show the range of tds in drinking water for animal use. table 7, tds range and type of animal classification [14]. tds range (mg/l) type of animal < 1000 domestic animals 1000 3000 horses 3000 5000 milk-livestock 5000 – 7000 meet-livestock > 7000 sheep table 8, classification of ground water depending on tds [14]. tds range (mg/l) type of water 2860 excellent water 6435 good water 7150 poor water 10000 very poor water 12900 water unsuitable for drinking purposes on basis of table 8 classification, fig.٧ shows that 41% of samples are within excellent ground water for animal use, while 33% are within good water category. then 74% of samples are suitable for animal use especially for sheep and meetlivestock animals. 6. conclusion 6.1. using the groundwater as drinking water for human depending on wqi values which are more than 50, all samples are not to be used for drinking water, because of the high concentrations of one or more of the water parameters which are above the permissible limitation (depending on iraqi and who drinking water standards) this cause increasing in the wqi value, which means decreasing in water quality. 6.2. using the groundwater for irrigation depending on sar and rsc values, the groundwater samples could be used for irrigation but this water may affect the physical properties of the soil because of the high value of sodium percentage in most of the samples. high sodium percentage will reduce the permeability of the soil and water infiltration slows to near zero which effects plant growth. an application of gypsum (caso42h2o) to the soil will reduce the effect of this problem because sodium will react with sulfate to form sodium sulfate (na2so4) which is a highly water soluble material that is leached from the soil. 6.3. using the groundwater for animals the study showed that depending on tds values of the groundwater samples, that the water is suitable to be used for animals especially for sheeps and meet livestock animals. 7. references [1] gilbert m. masters, wendell p. ela, “introduction to environmental engineering and science”, third edition, pp.(176-178), 2008. [2] mark j. hammer, mark j. hamme, jr., “water and wastewater technology”, sixth edition, pp.(127,128,155), 2009. [3] t. meenambal, r.n. uma, k. murali, “principles of environmental science and engineering”, pp. 2, 2005. [4] nosart aghazadeh and asghar asghari mogaddam, “assessment of groundwater quality and its suitability for drinking and agricultural uses in the oshnavieh area, northwest of iran”, journal of environmental protection, vol. 1, no. 1, march 2010. [5] r. k. khitoliya, “environmental pollution, management and control for sustainable development”, pp. 39, 2007. [6] mouna ketata-rokbani, monce gueddari, rashida bouhlila, " use of geographical information system and water quality index to assess groundwater quality in el khairat deep reem j. channo al-khwarizmi engineering journal, vol. 8, no.3, pp 63 -74 (2012) 73 aquifer (enfidha, tunisian sahel”, iranica journal of energy and environment 2 (2): 133144, 2011. [7] http:// ar.wikipedia.org/wiki/ العراقسكان . [8] http:// www.baghdad.gov.iq/الموقع / موسوعة بغداد .الجغرافي لمدینة بغداد [9] oliver schmoll, guy howard, john chilton, ingrid chorus, “protecting groundwater for health”, who, 2006. [10] swarna latha. p, nageswara rao. k, “assessment and spatial distribution of quality of groundwater in zone-ii and iii, greate visakhapatnam, india using water quality index (wqi) and gis”, international journal of environmental scinces, vol. 1, no. 2, 2010. [11] m. vasanthavigar, k. srinivasamoorthy, et al, “application of water quality index for groundwater quality assessment: thirumanimuttar sub-basin, tamilnadu, india” environmental monitoring and assessment, vol.171, no. 1-4, december 2010. [12] abdul hameed m. j., haider s. abid, bahram k. maulood, “application of water quality index for assessment of dokan lake ecosystem, kurdistan region, iraq”, journal of water resource and protection, 2, 792-798, 2010. [13] abdul hameed m. j. alobaidy, bahram k. maulood, abass j. kadem, “evaluating raw and treated water quality of tigris river within baghdad by index analysis”, journal of water resource and protection, 2, 629-635, 2010. المدیریة العامة لحفر االبار / وزارة الموارد المائیة العراقیة [14] .٢٠٠٥، كانون الثاني "ھیدرولوجیة مدینة بغداد"المائیة، الجھاز / العراقیة وزارة التخطیط والتعاون االنمائي [15] المواصفات القیاسیة "المركزي للتقییس والسیطرة النوعیة، "٤١٧العراقیة لمیاه الشرب رقم http://www.baghdad.gov.iq/ )2012( 7463 ، صفحة 3، العدد 8مجلة الخوارزمي الھندسیة المجلد ریم جالل اسحاق 74 الزراعيالمیاه الجوفیة لمدینة بغداد لالستھالك البشري والحیواني و مدى مالئمةدراسة ریم جالل اسحاق جامعة بغداد/ كلیة الھندسة الخوارزمي/ قسم ھندسة الطب الحیاتي reem_jchanno@yahoo.com :البرید االلكتروني الخالصة ر احد المصادر المھمة للمیاه خاصة للبلدان التي تعاني من شحة او انعدام المیاه السطحیة ، لذلك من الضروري دراسة نوعیة المیاه المیاه الجوفیة تعتب ,wqi, sar, rscویتم ذلك باستخدام عدة مصشرات مثل . او الحیواني او الغراض الزراعة الجوفیة والوقوف امام امكانیة اسخدامھا لالستھالك البشري na%, tds تم حفرھا بمناطق مختلفة من مدینة بغداد، حیث اظھرت النتائج نموذج لمیاه جوفیة اخذت من ابار 66من خالل ھذا البحث تم دراسة خواص tdsل ان مظم المیاه الجوفیة صالحة للزراعة، ومن خال sar, rscیشیر الى عدم مالئمة ھذه المیاه لالستحدام البشري بینما بین مؤشري wqiان .ومواشي اللحوممن النماذج یمكن استخدامھا لالستھالك الحیواني وباالخص االغنام %74نالحظ ان mailto:reem_jchanno@yahoo.com (microsoft word 100-106\315\355\307\311 \337\321\355\343 \346\317\307\346\317) al-khwarizmi engineering journal al-khwarizmi engineering journal,vol. 13, no. 2, p.p. 100106 (2017) design a vegetative filter strips length using vfsmod_w model for reducing sediments and pesticides hayat kareem shukur* dawood e. sachit** *department of civil engineering/ collage of engineering / university of al-mustansiryah ** department of environmental engineering/ collage of engineering / university of al-mustansiryah *email: hayat.azawi@okstate.edu **email: dawood.sachit@okstate.edu (received 4 october 2016; accepted 29 january 2017) https://doi.org/10.22153/kej.2017.01.005 abstract the vegetative filter strips (vfs) are a useful tool used for reducing the movement of sediment and pesticide in therivers. the filter strip’s soil can help in reducing the runoff volume by infiltration. however, the characteristics of vfs (i.e., length) are not recently identified depending on the estimation of vfs modeling performance. the aim of this research is to study these characteristics and determine acorrelation between filter strip length and percent reduction (trapping efficiency) for sediment, water, and pesticide. two proposed pesticides (one has organic carbon sorption coefficient, koc, of 147 l/kg which is more moveable than 100, and another one has a koc of 2070 l/kg which is less moveable than 1000 are presented, where the goal is to prevent 95% of incoming sediment and 85% of the incoming pesticide to reach a receiving stream in still water, oklahoma from a cultivated field (1250 m²),for 2 hour storm with 5 years return period. several vfs lengths were simulated including1, 3, 5, 6, 9, 11, 12, and 13 m. the results showed that the percent of reduction of sediment, pesticide, and water mainly depends on vfs lengths. moreover, considering the design storms range, the simulation illustrated that the optimal filter length was13m for silty clay loam. when the value of ���, was increased from 147 l/kg to 6070 l/kg, the filter length decreased from 13 to 9.5 because of the increase in trapping efficiency. in addition, the results revealed that the trapping efficiency was for sediment but not for water orpesticide which was highly impacted by the narrow filter strips. the amount of the rainfall and runoff of the designated field was larger than the infiltration capacity of filter strips, which resulted in low trapping efficiency for pesticide and water. keywords: models ,runoff, sediment, vegetative filter strip, , water quality, watershed planning. 1. introduction watershed planners were encouraged by the u.s environmental protection agency (usepa) to use a vegetative filter strip as a tool to control runoff quantity and quality [1] since the amount of surface runoff depends on the amount of rain and watershed characteristics such as soil type, land use, size, vegetation cover, soil moisture condition, and topography [2]. an effective way to minimize the amount of water and sediment and other contaminants in surface runoff from reaching a stream was needed [3]. such an effective way is the vegetative filter strip modeling system (vfsmod-w) which is a computer model to study hydrology, sediment and pollutant through vfs. three sub models were connected to the vfsmod model to study the buffer performance on an event by event basis; a petrovgalerkin finite element kinematic wave over land flow submodels, a modified greenampt infiltration submodel and university of kentucky sediment filtration model for grass area [4]. vfs is defined by grismer [6] as a vegetative land that is planted on purpose to trap sediment hayat kareem shukur al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 112 (2017) 101 and pesticide from runoff water. the goal of vfs is to protect surface water in a number of ways; (1) they trap as much as 75 to 100 percent of water’s sediment by infiltrating the surface water; (2) they hold nutrients in runoff through adsorption to soil particles; (3) they increase degradation so that the pollutant become less toxic; (4) they prevent over 60% of certain pathogens form the runoff. when designing vfs, there are some factors that need to be taken into account such as slope, site preparation, soil conditioning, width, placement, maintenance, and monitoring. slopes less than 5 percent are work in vfs, while slopes greater than 15 percent is not recommended. grismer [6] concluded that the width of filter strips is an important element affecting the performance of vfss. as the strips width increases the amount of runoff and sediment also increases. the design of filter strips has been studied by many researchers and there is an agreement that the length of filter strips needed to obtain a certain level of trapping efficiency is highly variable [5]. therefore, to effectively measure the length of vfs, it is necessary to study the relationship between the amount of sediment and pollutant that could be stopped and the length of filter strips. dosskeyet al [3] evaluated a vegetative filter strip model to develop a design aid that is easy to use. slope, soil texture, field length and field covers were used as variablesto determine the amount of sediment by using ten different combinations of lengths and widths. they reported that the narrow filter strips can be highly effective in some cases, while in others, even a small impact, could not be achieved at any practical width. in addition to that, it was found that as the slope increased or the texture of soil become finer, the trapping efficiency decreased and the field runoff increased as shown in figure (1). moreover, as field length or c factor (crop factor) increased the amount of runoff also increased, thus, the trapping efficiency of sediment become lower than that of shorter field with lower c factor (better condition). fig. 1. sediment trapping efficiency as a function of vfs width for two different sites having two different soil [3]. dillahaet al [9]found that increasing vfs length will help to increase the trapping efficiency up to a certain level thereafter, any additional length does not make any improvement in filter performance. furthermore, holvoet et al [2]indicated that the best management practices can decrease the level of different pesticide input to a large extent but, more field study should be made in combination with modeling exercises in order to achieve good results whose measurements are most effective. barfield et al [1], on the other hand, presented a steady state model to estimate the trapping efficiency of sediment in a filter strip under different variables. the trapping efficiency,��, of a filter strip can be calculated as follows [1]: �� � �� � …(1) where ��� and ��� are incoming and outgoing sediment load per unit channel width. the aim of this research is to study the characteristics of vfs (i.e., length) and determine a correlation between filter strip length and percent reduction (trapping efficiency) for sediment, water, and pesticide. 2. materials and method the vegetative filter strip modeling system (vfsmod-w) version 5.x[4] was used to estimate the reduction of sediment, pesticide, and water by many different lengths of grass filter strip. a field site in oklahoma was selected to monitor the performance of vfs. the design will receive water and sediment from a 50 m wide by 25 m long source area. by using table (1)with the soiltexture triangle of 17.1 % sand, 54.1 % hayat kareem shukur al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 112 (2017) 102 silt, and 28.9 % clay, the soil type was found to be silty clay loam type d[10]. for type d, cultivated area, and row cropscurve number is equal to 91 [9]. soil hydraulic parameters which are shown in table (1) were taken from the united states department of agriculture (usda) ssurgo database [9]. default parameters of the vfs model were used and bermuda grass type was assumed. the flow pattern of the source area is shown in figure (2). table 1, input parameters for the vfsmod-w[8,9]. parameter model input value soil type silt clay loam with 17.1% sand, 54.1% silt,and 28.9% clay and 2.58% organic carbon. soil hydraulic conductivity 9.3 cm/hr soil bulk density 1.44 �/��� average section at the wetting front (sav) 0.43m intial water content �� 0.17 slope 5.25 % crop factor (c) 0.05 practice factor (p) 0.5 mediam parcticle size of incomin sediment ( ���) 0.001 adsorption coefficient (���) 147 l/kg -6070 l/kg fig. 2. case study characteristics (source area). the porosity,(∅), which is the fraction of void space in the soil, is defined by the ratio: ∅ � !" !# � 1 − &'() �*+,-./ 012.-�(* �*+,-./ (2.65 � ��3) …(2) where6!is the volume of void space, and 67is the total or bulk volume of the materials [11]. vfsmod required storm-based hourly rainfall data. in this study, the natural resource conservation soil method (nrcs) for calculating the rainfall excess was used for5year-2hr storm, type ll curve [10]. the dimensionless precipitation, 89 8:; , is the cumulative rainfall (<=)as function of time divided by the total 24-hour rainfall amount (<>?). the 24hr, 5year storm is equal to 5 inches[10]. the peak rainfall intensity occurs at the time when the slope of the cumulative rainfall distribution is the steepest, which for the nrcs 24-h hyetograph type ii is from 11hrto 13 hr. the rainfall event was calculated to be 68 mm as shown in table (2). table 2, rainfall depth calculations using nrcs method. time, hr @a @bc depth, in 11 0.235 0.0 11.5 0.283 0.25 12 0.663 1.9 12.5 0.735 0.36 13 0.772 0.18 d b. ef gh = 68mm 3. design guide procedures one of the most important steps to develop a design guide for evaluating vfs performance is that the user must provide inflow hydrographs from the source area. using the inputs of hyetograph in figure (3) and the hydrograph in figure (4), vfsmod simulates the transport and deposition of sediment within the vfs. in the vfs model, the field length is defined as the distance from the edge of the field to the edge of the vfs as shown in figure (2). vfs width which is the same as the field width is calculated by dividing the area of the field (1250 m²)by the field length. several vfs lengths (1, 3, 5, 6, 9, 11, and 13 m) were used in the simulation to estimate the reduction of sediment, runoff inflow, and pesticide as explained in table (3). then, the results were developed into graphical representation which are easier to understand than those of the tables as shown in figure(5).in addition, to study the effect of the width of the filter strip on the trapping efficiency of the pesticide, the width was reduced to 90%, 75%, 25%, 10% and 5% of the field width and applied hayat kareem shukur al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 112 (2017) 103 to the model. the percent reduction in the pesticide which were obtained from the vfsmod simulation are listed in table (4) and were developed into graphical representation as illustrated in figure (6). fig. 3. hyetograph of the case study. fig. 4. hydrograph of the case study using vfsmod. table 3, vfsmod-w output file. vfs length, m source length, m vegetation type h,cm sediment reduction, % runoff inflow reduction, % pesticide reduction, % 1 24 bermudagrass 1.35 74.187 10.19 35.018 3 22 bermudagrass 1.35 89.699 23.142 52.766 5 20 bermudagrass 1.35 94.174 32.056 62.36 6 19 bermudagrass 1.35 94.582 34.84 66.672 8 17 bermudagrass 1.35 96.514 40.289 71.67 9 16 bermudagrass 1.35 96.89 42.164 77 11 14 bermudagrass 1.35 97.8 56.294 78.6 12 13 bermudagrass 1.35 98 58.361 79.8 13 12 bermudagrass 1.35 99.47 60.149 89.889 fig. 5. percent reduction in sediments, pesticides, and runoff relative to vegetative filter strip (vfs) length (1, 3, 5, 6, 9, 11, 12, and 13 m) with organic carbon sorption coefficient, ijk of 147 l/kg. table 4, values of vfs width and trapping efficiency of pesticide. width, m trapping efficiency % 50.0 89.889 45.0 89.115 37.5 86.539 25.0 79.566 15.0 63.341 5.0 41.756 hayat kareem shukur al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 100106 (2017) 104 fig. 6. relationship between vfs widths and trapping efficiency of pesticide. 4. results and discussion the simulation results clearly showed that increasing the filter strips length will help to increase the trapping efficiencies for sediment and pesticide as shown in figure (5).the filter strip as narrow as 5 m was estimated to trap nearly 95% of the incoming sediment and only 62% of incoming pesticide, while 13 m strips trapped 99.47% of incoming sediment and 89.9% of incoming pesticide(see figure(5)). thus, the relatively narrow filter strips can have great impact on the trapping efficiency for sediment but not for water or pesticide. the trapping efficiencies of a given length of filter strips also depend on the spacing of vegetation being planted and the kind of material being trapped. high trapping efficiencies were estimated for sediment and much lower trapping efficiencies were estimated for water under the same conditions as displayed in figure (5). the low trapping efficiencies for water illustrates that rainfall plus field runoff often greatly exceeds the infiltration capacity of filter strips. the filter length decreased from 13 to 9.5 when the value of ( ���) was increased from 147 l/kg to 6070 l/kg because the trapping efficiencies of the sediment and pesticide increased as presented in table (5). the vfs width also affected the trapping efficiency, as the width increases, the trapping efficiency also increases as shown in figure (6). table 5, values of ilm and vfs length, m ilm sediment reduction, % pesticide reduction, % 13 6070 99.47 94.692 11 6070 90.310 90.616 9 6070 97.244 84.238 9.5 6070 97.385 85.088 5. conclusion vegetation filter strips (vfs) are areas planted on purpose along streams, ponds, and lakes to remove sediment, organic materials, and chemicals carried in runoff or wastewater. the vfsmod model is recommended to use by the u.s environmental protection agency (usepa) as a design aid to remove the amount of sediment, organic materials, and chemical carried in surface water. the results showed that the vegetative filter strips length is the most important parameter that directly affects the trapping efficiency. increasing the filter strips length will help to increase the trapping efficiency up to a certain level thereafter, any additional length does not make any improvement in filter performance. to prevent 85% of incoming pesticide to reach a receiving stream, it requires longer filter strips than sediment. the optimal filter length obtained was 13m. high trapping efficiencies were estimated for sediment and much lower trapping efficiencies were estimated for water under the same conditions. the low trapping efficiencies for water illustrates that rainfall plus field runoff often greatly exceeds the infiltration capacity of filter strips. when the value of adsorption coefficient (���) was increased from 147 l/kg to 6070 l/kg, the filter length decreased from 13 m to 9.5 m because the trapping efficiencies for sediment and pesticide increased. the advantages of vfsmod model over other models used to simulate vfs are the flexibility to change the parameters (slope, vegetation type, spacing of vegetation, etc.) along the filter and handling of complex storm pattern and intensity. based on this study, it is recommended to implement vegetation filter strips in many regions in iraq along the numerous streams where the prevalent areas are agricultural fields which are full of pesticides and fertilizers used by farmers. in addition, since the soil characteristics are important factors in the vfs hayat kareem shukur al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 100106 (2017) 105 performance, field studies including evaluation of the implemented vfs are recommended as well. 6. references [1] barfield, b.j., tollner, e.w., hayes, j.c., 1979. filtration of sediment by simulated vegetation i. steady-state flow with homogeneous sediment. transactions of asae 22 (5): 540–545. [2] holvoet, k.m., seuntjens, p., and vanrolleghem, p.a., 2007. monitoring and modeling pesticide fate in surface waters at the catchment scale. ecological modeling, 209:53-64. [3] dosskey, m. g., helmers, m. j., and eisenhauer, d. e. 2008. a design aid for determining width of filter strips. journal of soil and water conservation, 64 (4):232-241. [4] munoz-carpen, r., and parsons, j. e., (2010). vfsmod -w: vegetative filter strips modeling system v.5.x.: university of florida. http://abe.ufl.edu/carpena/vfsmod/. [5] munoz-carpen, r., parsons, j. e., and gilliam, w. j., (1999). modeling hydrology and sediment transport in vegetation filter strips. journal of hydrology, 214:111-129. [6] grismer, e.m., 2006. vegetative filter strips fot nonpoint source pollution control in agriculture. anr publication 8195. california 94608-1239. [7] dillaha, t.a., renea, r, b., mostaghimi, s., lee, d., 1989. vegetative filter strips for agricultural nonpoint source pollution control. transaction of asae 32 (2): 491-496. [8] united state department of agricultural (usda). (2013). web soil survey. retrieved from <http://websoilsurvey.nrcs.usda.gov/app/hom epage.htm> [9] united states department of agriculture (usda), 2012. geospatial data gateway. retrieved from <datagateway.nrcs.usda.gov>. [10] haan, c. t., barfield, b. j., and hayes, j. c., (1994). design hydrology and sedimentology for small catchments. academic press, inc., san diego, california. [11] james, r., james, w., finney, k., nandana, p., lucas, w., & lee, m. (2012), urban drainage modeling workbook (pcswmm and swmm5.0.002, computational hydraulic international(chi). canada. )2017( 100-106 صفحة ،2العدد ،13المجلد الهندسية الخوارزمي جلةم حياة كريم شكر 106 للحد من الرواسب موديل vfsmod_w استعمالبتصميم طول شريحة الغطاء النباتي والمبيدات الحشرية **داود عيسى ساجت حياة كريم شكر* لجامعة المستنصريةا /الهندسة المدنية/ كلية الهندسة *قسم لجامعة المستنصريةا /كلية الهندسة /هندسة البيئة *قسم * dawood.sachit@okstate.edu :البريد االلكتروني* hayat.azawi@okstate.edu :البريد االلكتروني** الخالصة vfsـال و بحيرة . تصممامجرى مائي كنهر إلى) هي أداة مفيدة تستخدم للحد من الرواسب والمبيدات الحشرية الداخلة vfsشرائح الغطاء النباتي ( ، الخصائصمن جهة اخرى. طة عملية الترشيحسابوجم الجريان السطحي حقرب المجاري المائية وبموازاة خطوط جريان الماء فتساعد على خفض راسة هذه الخصائص وإيجاد .لهذا كان من الضروري دvfsكطول الشريحة مثال ليست حاليا محددة على أساس النمذجة التنبؤية ألداء الطبيعية الفيزيائية ولها ط مساحة متر ل ١٣وكذلك ١٢، ١١، ٩، ٦، ٥، ٣، ١ عالقة بين طول الشريحة والنسب المئوية للرواسب والمبيدات المنخفضة. تم فحص عدة أطوال لفترة رجوع كل ة عاصفة مطري٢ hrs تستقبل األمريكيةفي الواليات المتحدة stillwaterمتر لتربة طينية غرينية في مدينة ٥٠عرضها متر و ٢٥ اض نسبة انخف الحصول على قابلية حركة قليلة بهدف يذ واآلخرقابلية حركة عالية يفحص نوعين من الكربون العضوي ذ أيضا خمس سنوات . تم ومقدار المبيدات المنخفضة vfsمن الرواسب الواردة الى المجرى المائي. لوحظ وجود عالقة جيدة بين طول ال %٩٥ن المبيدات و م %٨٥ مقدارها .لى نسبة الرواسب والمبيدات المنخفضة ع اً كبير اأثر vfs ـكما تبين ان لطول شريحة ال اً متر ١٣لطول ` al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 8, no. 2, pp 54 -62 (2012) the stability conditions of the pump structure vibration nassir hassan abdul hussain al hariri department of machines and equipment/instate of technology-baghdad (received 27 march 2011; accepted 30 january 2012) abstract the general approach of this research is to assume that the small nonlinearity can be separated from the linear part of the equation of motion. the effect of the dynamic fluid force on the pump structure system is considered vibrates at its natural frequency but the amplitude is determined by the initial conditions. if the motion of the system tends to increase the energy of the pump structure system, the vibration amplitude will increase and the pump structure system is considered to be unstable. a suitable matlab program was used to predict the stability conditions of the pump structure vibration. the present research focuses on fluid pump problems, namely, the role played by damping coefficient c, damping factor d and angular speed ω (termed the ratio ( ) n  ) and the determining stability of a centrifugal pump structure. the data demonstrate substantial rotor dynamic effects, a destabilizing chart appears to be inversely proportional to the d, c, and ω, and resonance changes significantly with flow rate. keyword: stability, amplitude, vibration, resonance, pump. 1. introduction because of the complex spectra behavior of pump structure system it is not easy to interpret the results of pressure or velocity measurements of such systems [1]. the pump vibration comes from several sources that include mechanical causes of vibration, i.e. unbalanced rotating components, damaged impellers and non concentric shaft sleeves are common, non-laminar flow and operating the pump at a critical speed [2]. frequencies below running speed can be caused by acoustical resonance. generally these effects are due to the impeller passing and discharge diffuser [3]. able to originate internally or externally, an excitation force is the only cause of vibration. repeating forces create the vibration problems most commonly associated with centrifugal pump. these forces are often caused by the rotation of imbalanced, misaligned, or worn pump components [4]. however, in real structures the energy input by the flow has a finite limit, because the fluid forces on the structure are limited. thus the amplitude of unstable region can only grow until it is limited by nonlinearities in the structure itself [5]. resonance can be avoided by changing a systems ' frequency, which is determined by the mass, stiffness and damping properties of all of the components involved, including the pump, base, motor, piping-coupling, guard, foundation, etc. if the resonance vibration is just below the natural frequency, the stiffness of the system should be increased so the vibration frequency shifts above the natural frequency. if the resonance vibration is just above the natural frequency, the systems ' mass should be increased, shifting the vibration frequency below the natural frequency [6]. many vibration problems are results of interactions among a system pump, motor, fluid, piping and structure. this requires systems approach to vibration analysis, rather than the investigation of individual components [7]. a nonlinear system could have more than one equilibrium, some of which may be stable and others unstable as it is clearly noticed in the stability charts of the pump structure vibration[8]. nassir hassan abdul hussain a l-khwarizmi engineering journal, vol. 8, no. 2, pp 54 -62 (2012) 55 2. theory the investigated equation of motion of the model pump structure in y-axis [9] is: m + ( c – 3kv ) + ky = fƒ …(1) let a= m c = m dm2 and b= k/m + a + b y m f f = 0 …(2) to solve eq. (2) ,a particular solution is assumed as: y = y sin (ω t) substituting eq. (2) as: ω 2 y sin (ω t) + a ω y cos (ω t) + b y sin (ω t) m f f = 0 …(3) the stable and unstable regions of equation (3) depends on the parameters a and b and are shown in the charts of stability condition of the pump structure system. substituting and rearranging eq. (3), the parameter b becomes: b = )sin(.. tmy f f  + ω2 – a ω cot (ωt) …(4) substituting the values and after modifying and neglecting the small values of eq.(1) the amplitude of the oscillating motion of the pump is obtained [9]: 2222 ])(2[])(1[ nn f dk f y       …(5) by substituting values y and k= m. ω2 and substituting eq. (5) in eq. (4) as: )cot(1 )sin( ])(2[])(1[ 2222 t a t d b nn          …(6) the conditions of stability of the pump structure are given by the roots a and b as: b > 0 stability is increased b < 0 instability is increased a > 0 always and pump structure system is stable equation (6) is known as the mathieus equation [10]. the stable and unstable regions of eq.(6) depends on the parameters a and b and are shown in the stability charts obtained. there are no known closed form solutions to the nonlinear differential equations describing the response of the pump structure used in an oscillating flow. it is possible to numerically integrate these nonlinear equations to obtain a solution. at resonance ω = ωn if the frequency of the oscillating flow is much greater than the natural angular frequency of the structure, then the pump structure; becomes intensive to high frequency forces that energy in to the pump structure and cannot be transfer the response approaches zero [11]. therefore the parameter b in eq.(6) becomes: b= n d sin .2 + 1 nm a . cot (ωnt) …(7) the parameter b will be positive or negative depending actually upon the time of oscillating t and on the damping factor d. the matlab program is used to solve the equation of motion (6) to get the stability charts. and reach the following assumptions: r = ( n  ) 2 m = [ 1 ( n  ) 2 ] 2 m = [ 1 – r ] 2 s = [ 2. d. ( n  ) 2 ] 2 s = [ 2. d. r ] 2 2222 ])(2[])(1[ nn dn      n = sm  substituting these values in eq.(6) as: b = )sin( t n  + 1 – (  a ) cot ( ωt ) nassir hassan abdul hussain a l-khwarizmi engineering journal, vol. 8, no. 2, pp 54 -62 (2012) 56 matlab program >> % we will now get stability condition at ω= 112 >> t= 0.001;0.002;0.003;0.004;0.005;0.006;0.007;0.008; 0.009;0.012;0.016;0.020; >> r = 0.221;0.307;0.469;0.623;0.854;1;112;1.44;1.74;1. 94;2.175; 2.509; >> d = 0.01;0.06;0.10;0.15;0.25;0.35;0.40;0.55;0.65;0.75 ;0.85;0.95; >> a = 2 * ω * d; >> a >> m = (1-r)^2 >> m >> s = (2*d*r)^2 >> s >> n = sqrt (m+s) >> n >> b= n/sin(ω *t)+1-(a/ ω)*cot(ω *t) >> b to draw the stability charts of the pump structure at different values of times, ratios of angular speeds with natural speed and damping factors, the matlab program was used: >> % we will give variables for plot at ω= 112 >> a=[ 2.24; 13.4; 22; 33; 56; 78; 89; 123; 145; 168; 190; 212]; >> b=[ 7.79; 3.98; 2.79; 2.18; 1.68; 1.39; 1.32; 1.16; 1.161; 1.52; 2.26; 3.63]; >> % we will plot >> plot (a,b,'-ob','linewidth',2,'markersize',1) >> xlabel('a') >> ylabel('b') >> title('\bf stability condition') the matlab program of the stability condition at resonance state where ω= ωn= 238 is: r= 1 m= 0 >> % we will now get stability condition at resonance state ω=ωn=238 >> t = 0.001;0.002;0.003;0.004;0.005;0.006;0.007;0.008; 0.009;0.012;0.016;0.020; >> d = 0.01; 0.06; 0.1; 0.15; 0.25; 0.35; 0.40; 0.55; 0.65; 0.75; 0.85; 0.95; >> a= 2* ωn * d; >> s= (2*d)^2; >> s >> n= 2*d; >> b= n/sin(238 *t)+1-(a/ 238)*cot(238*t); >> b the matlab program to plot the stability condition at ω= 132is: %%we will now give the variable for plot1 of stability chart at 0mega=132 a=[2.64;15;26;39;66;92;105;145;171;198;224;250 ]; b=[6.11;3.21;2.32;1.87;1.51;1.32;1.31;1.26;1.33;1 .85;3.03;6.34]; %now we will plot the plot1 of stability at omega=132 plot(a,b,'-ob','linewidth',2,'markersize',2) % we will give values for plot2 of experimental a=[2.64;15;26;39;66;92;105;145;171;198;224;250 ]; b=[0;3;4.3;3.9;3.6;2.5;6.3;5.8;4.5;6.9;7.8;9.1]; % we will plot plot2 of experimental % but we must use hold command to be able to show the the plot2 at the same window hold on plot(a,b,'--*r','linewidth',2,'markersize',2) % we will give values for plot3 at resonance a=[4.76;28;47;71;119;166;190;261;309;357;404;4 52]; b=[1;1.02;1.07;1.15;1.33;1.60;1.88;2.54;3.38;11;3.9;-0.81]; %% we will plot for plot3 at resonance plot(a,b,'-.+k','linewidth',2,'markersize',2) xlabel('a') ylabel('b') legend('132','exp','res',0) displacement amplitudes are used at low vibration frequencies typically between ( 17-62 ) hz. high displacement amplitudes at low frequencies can cause a considerable amount of stress damage to a pump structure. using matlab program determined the stability conditions at angular speeds ω= [112, 132, 163, 188, 220, 238, 251, 286, 314, 332, 351, 377]. and matlab program was used also to plot the stability conditions of the pump structure at these angular speeds. fig.2.indicates the particular stability condition at angular speed ω=112. it has two small regions of stability and large area of instability. it is nearly similar to stability in fig.3. in which it is at angular speed ω= 132 at the ratios of angular speeds (ω/ ωn)=(1/2.1 and 1/1.8). nassir hassan abdul hussain a l-khwarizmi engineering journal, vol. 8, no. 2, pp 54 -62 (2012) 57 3. experimental method the measurements method was tested on laboratory test instrument “pumps training system lab-volt”. the photographic picture of the research experiment is shown in fig.1. in the laboratory test, water is circulated from the water tank. the speed is measured by using an electromagnetic flow meter. the static pressure is measured, relative to atmospheric pressure at the suction and discharge flanges of the pump. when operating the pump will act as an active element in the test loop . in this experiment pump induced pulsations are suppressed by coherence analysis with the external source signal as a reference. measurements should be taken at operating speed for constant speed motor and at varying speeds for pump operating on variable speed drives [12]. fig. 1. the photographic picture of the research experiment [9]. this research is carried out by using the type of centrifugal non-positive displacement, which has two kinds of openings; one opening is for flowdrag and the other opening is for flowpushing. the drag opening is connected with fluid tank, and the pushing opening is joined with flowmeter to measure the fluid flow discharge. then there is a valve for hindering the fluid flow which is coupled with its valve adjustment in parallel. the motor is linked with the pump, and the regulation is lying on the motor speeds by varying the frequencies. it takes the readings of the fluid flow discharge, and the pressure readings are taken by the manometer. the readings of the vibration amplitudes of the pump structure are taken by the vibrometer, and the rpm of the propeller of the pump are also taking. the readings are shown in the appendix of table.1. and table.2. the value of the natural angular speed ωn=238 is determined by using the analyzer. table1, the measured parameters of the fluid flow in the pump [9]. frequency f [hz] angular speed ω [rad/s] vibration amplitude rms speed of pump [rpm] 0 0 0 0 17.9 112 3 1029 21 132 4.3 1207 26 163 3.9 1495 30 188 3.6 1725 35 220 2.5 2012 38 238 6.3 2185 40 251 5.8 2300 45 283 4.5 2587 50 314 6.9 2875 55 345 7.8 3162 60 377 9.1 3450 table2, shows the measured and calculated parameters of the pump structure [9]. total mass m [kg] measured mass mo[kg] entrained mass mf [kg] cross-sec. of pump a [m 2 ] 7.2 1.2 6 0.00567 stiffness of pump k [n.s/m] measured angular speed of pump ωn [ rad/s] width of pump b [m] diameter of pump d [m] 47203 238 0.0265 0.085 nassir hassan abdul hussain a l-khwarizmi engineering journal, vol. 8, no. 2, pp 54 -62 (2012) 58 4. results and discussion figure (4) shows the stability chart taking another form with small increasing in the zone of stability at angular speed ratio (1/1.26). fig.5 the area of stability decreases to some values, then the curve increases sharply to some extent. in fig.6. and fig.7. show the stability charts reduce at angular speed ratios more than one, i.e. (ω/ ωn) = (1/0.94 and 1/0.75), they are very close to each others. it is concluded from the figures that the stability charts depend on the effect of the time of occurring of the vibration of the pump structure, in which parameter b plays the main role than the other parameters. it means that at the time occurring the amplitude of vibration at natural angular speed ωn = 238 was higher than that of the lower angular speeds. however, it was predicted that the time of vibration amplitudes at lower frequencies were near zero values, which gave almost straight line at zero line of b parameter. the parameter b is playing a more important role than the values of a parameter at all values of the angular speeds, because the values of a parameter are always positive, while the values of b parameter are positive or negative values; they depend on the values of the times of vibration amplitudes. the stability charts are obtained in the figures, by keeping natural angular speed ωn and some other parameters are constants and then varying angular speed ω to vary the ratio ω/ ωn. it will be noticed actually, if the horizontal shaft is run at angular speed lower than natural angular speed ωn = 238, then it will be instabilized at angular speeds 112, 132, and 163 which are nearly equal to half value of natural angular speed as shown in figures 2, 3, and 4. in figures 5, 6, and 8, the behavior of the stability charts are different at angular speeds 188, 220 and 251 because the stable areas were noticed evidently at negative b parameter, if the variable damping factor is assumed with constant value of the stiffness. it is concluded also from the figures of stability charts, that the region between curves of theoretical stability charts at ω=(112 and 132) and of resonance chart at ωn = 238 is called critical zone, which here it represented in small area. but at ω = (163, 188, 220, 251 and 286) critical zone coincides at the same line of each curve for certain extent of values of parameter a which is always positive. however, this means the system of the pump structure has the same critical limit. then with th increasing the values of ω = (314, 332, 351 and 377) the possibility of the critical zone begins to increase gradually for small area also at positive values of parameter b. the ratio of error between the theoretical and experimental is between ( 0.2590 and 0.1403 ) for ω=(112 377). fig. 2. stability chart at ω= 112. when blue line represents ω= 112 ,red line exp. represents experimental ,black line res. represents resonance. fig. 3. stability chart at ω= 132. nassir hassan abdul hussain a l-khwarizmi engineering journal, vol. 8, no. 2, pp 54 -62 (2012) 59 fig. 4. stability chart at ω= 163. fig. 5. stability chart at ω= 188. fig. 6. stability chart at ω= 220. fig. 7. stability chart at ω= 251. fig. 8. stability chart at ω= 286. fig. 9. stability chart at ω= 314. nassir hassan abdul hussain a l-khwarizmi engineering journal, vol. 8, no. 2, pp 54 -62 (2012) 60 fig. 10. stability chart at ω= 332. fig.11. stability chart at ω= 351. fig. 12. stability chart at ω= 377. 5. conclusions from the results obtained the following conclusions can be withdrawn: 1the stable and unstable regions of the equation of motion eq.(6) depend on the parameters a and b which are shown in the stability charts figures. 2very small values for time of vibration amplitudes are required to get accepted results. if time t was not sufficiently small, the results would be very inaccurate. 3the accuracy of the procedure increases as the value of the dynamic fluid force and damping forces decrease relative to the inertial and spring forces in the equation of motion. 4parameter b played a more important role than parameter a at values of angular speeds, naturally, because the parameter b depends on angular speeds, dynamic fluid force, damping factors and different values of time of vibration amplitudes. 5it is noticed that the effect of pump structure damping is important near the ratio ω/ ωn which is between 0.45 and 1.58. 6it is pointed out that a typical swirl velocity ratio at inlet ( pump discharge ) would be about 0.65 and may not be therefore large enough for the resonance to be manifest. nomenclature m total mass of the model pump structure [kg] c damping coefficient of the pump structure [n.s/m] kv fluid force velocity coefficient [n.s/m] k stiffness of the pump structure [n/m] ff total fluid force [n] ω measured angular speed of the pump [rad/s] ωn natural angular speed of the blades of the model pump structure immersed in the fluid [rad/s] f frequency of the pump structure [hz] d damping factor of the pump nassir hassan abdul hussain a l-khwarizmi engineering journal, vol. 8, no. 2, pp 54 -62 (2012) 61 6. references [1] jong christiaan arnoldus fraciscus de, "analysis of pulsations and vibrations in fluid – filled pipe system", eindhoven university of technology, thesis eindhoven – ref. isbn 90 – 386 – 0074 – 7, 1994. [2] www.mcnallyinstitute.com. [3] www.scribd.com. [4] hpac engineering, " applications & resources pumping and piping, examining causes of pump vibration", april 2009. [5] frances, tse, ivan morse & rolland t. hinple, " mechanical vibrations theory and applications", pub. allyn and bacon, sc. 1998. [6] bill watts and joe van dyke, " an automated vibration-based expert diagnostic system", sound & vibration, sept. 1993. [7] http://en-wikipedia.org/wiki/pump. [8] bill watts, " triaxial vibration spectral data, an important ingredient for proper diagnosis", dli engineering, 253 winslow way west, bainbridge island, wa, 1998. [9] nassir hassan abdul hussain, “the effect of fluid force on the pump structure vibrations", second scientific conference of the college of engineeringuniversity of al – qadisiya, pp. 420-435, 1920 oct. 2009. [10] william f. thomson, " vibration theory and application, george alien and anwin ltd, london, 1995. [11] yoshida, y. , murakami, y. , tsurusaki, t. and tsujimoto, y. " rotating stalls in centrifugal impeller / vaned diffuser system", proc. first asme / jsme joint fluids eng. conf. , fed-107, 125-130, 1991. [12] pump training system lab-volt, no. 4606, work orders-instruc. 37894-20, usa, 2004. http://www.mcnallyinstitute.com/2009 http://www.scribd.com/2010 http://en-wikipedia.org/wiki/pump (2012 )54 62 ، صفحة2، العذد 8 مجلة الخوارزمي الهىذسية المجلذواصر حسه عبذ الحسيه 62 حالة اإلتسان إلهتساز هياكل الضاغط واصر حسه عبذ الحسيه الحريري تغذاديعهذ انتكُىنىجُا / قسى انًكائٍ وانًعذاخ الخالصة ونقذ أخزخ تُظش اإلعتثاس تأحُشاخ قىج . نفهى انطشَقح انعايح نهثحج فقذ فشض قهُم يٍ انجضء انغُش خطٍ تأٌ َفصم يٍ انجضء انخطٍ نًعادنح انحشكح إرا كاٌ َظاو انحشكح ًَُم نضَادج . انسائم انذَُايُكُح عهً َظاو هُكم انضاغظ، حُج أَه َهتض عُذ انزتزتاخ انطثُعُح ونكٍ َحسة انًذي يٍ انششوط األونُح انًُاسة نتخًٍُ حانح matlabنقذ أستخذو َظاو . انطاقح نُظاو هُكم انضاغظ، فسىف َضداد يذي اإلهتضاص وَعتثش َظاو هُكم انضاغظ غُش يتضٌ ، d، عايم انتخًُذ cانثحج انحانٍ َشكضعهً يشاكم انسائم نهضاغظ، إسًُا نهذوس انحادث تىاسطح يعايم انتخًُذ . اإلتضاٌ إلهتضاص هُكم انضاغظ (انتٍ عثشخ تانُسثح)وانسشعح انضاوَح n  انثُاَاخ تظهش تىضىح . وكزنك فٍ حساب انخثاتُح وانصفح انًًُضج نهُكم انضاغظ رو انطشد انًشكضٌ ( ( . وكزنك انشٍَُ َتغُش تشكم كثُش يع يعذل انجشَاٌ d, c, ωانتأحُشاخ انحقُقُح نهًحىس انذواس انذَُايُكٍ، ويُحُُاخ عذو اإلتضاٌ تظهش انعالقح انعكسُح يع محمد خليل al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 8, no.4, pp 9-25 (2012) senserless speed and position of direct field orientation control induction motor drive mohammed khalil hussain department of engineering affairs/university of baghdad email: mohammedkhalilhussain@yahoo.com (received 25 december 2011; accepted 19 september 2012) abstract direct field-orientation control (dfoc) of induction motor drives without mechanical speed sensors at the motor shaft has the attractions of low cost and high reliability. to replace the sensor, information on the rotor speed and position are extracted from measured stator currents and from voltages at motor terminals. in this paper presents direct field-orientation control (dfoc) with two type of kalman filter (complete order and reduced order extended kalman filter) to estimate flux, speed, torque and position. simulated results show how good performance for reduced order extended kalman filter over that of complete order extended kalman filter in tracking performance and reduced time of state estimation. key words: sensorless , direct field orientation control, kalman filter, complete order extended kalman filter, reduced order extended kalman filter. 1. introduction electric drives based on induction motors (im) are widely used in industrial applications. high performance in terms of fast dynamics and load torque rejection, good tracking capability of speed reference in a wide speed range and high power efficiency are normally obtained with control algorithms based on speed feedback. on the other hand, there exist applications where low/medium performance are required, cost reduction and high reliability are mandatory, or hostile environment does not allow to use speed sensors. in these fields, speed sensorless im control can be profitably applied [1]. field orientation control of an induction motor (im) allows for a more direct command of both torque and flux than was possible with other variable-frequency techniques. with field orientation, torque and flux are commanded in a decoupled manner, and the behavior of a dc motor is reproduced [2]. sensorless induction motor drives have reached the status of a maturing technology in a broad range of applications ranging from low-cost to high performance systems. eliminating the speed sensor on the motor shaft represents a cost advantage, which combines favorably with increased reliability due to the absence of this mechanical component and its sensor cable. a motor without speed sensor is indicated for operation in hostile environments [3]. in this paper, i will propose a stochastic observer of state (kalman filter) to consider rotor flux, the speed, the load torque and the position of the rotor. initially we present an observer of state in complete order ekf then of a reduced nature ekf. the introduction of this last makes it possible to reduce the dimension of the observer and thus computing time which facilitate the establishment of the operation of observation on a device in real time. 2. a review of previous work there are a lot of papers dealing with kalman filter, especially with extended kalman filter (ekf). in [4] murat barut et al. described mailto:mohammedkhalilhussain@yahoo.com mohammed khalil hussain al-khwarizmi engineering journal, vol. 8, no.4, pp 9 -25 (2012) 10 extended kalman filter (ekf) algorithm to be used for the direct vector control of induction motors. in [5] murat barut et al. presents extended-kalman-filter-based estimation algorithms that could be used in combination with the speed-sensorless field-oriented control and direct-torque control of induction motors (ims) . in [6] américo vicente leite et al. presents speed estimation based on a reducedorder extended kalman filter (ekf), instead of a full order ekf in induction motor. in [7]américo vicente leite et al. presents an application of the extended kalman filter (ekf) to the simultaneous on-line estimation of the dq rotor flux components and all the electrical parameters of a vector controlled induction motor. in [8] mickaël hilairet et al. presents effective implementation of an extended kalman filter used for the estimation of both rotor flux and rotor velocity of an induction motor. in [9]murat barut presents extended kalman filter (ekf) based estimation technique for the solution of the on-line estimation problem related to uncertainties in the stator and rotor resistances inherent to the speedsensorless high efficiency control of induction motors (ims) in the wide speed range as well as extending the limited number of states and parameter estimations possible with a conventional single ekf algorithm. in [10] václav šmídl et al .presents performance of square-root extended kalman filter (ekf) based on reduced order models for sensorless control of permanent magnet synchronous motor (pmsm) drives is studied. . in [11] s. kumar et al. presents design and implementation of extended kalman filter (ekf), unscented kalman filter (ukf) and neural state filter (nsf) for the state estimation of a three-phase induction motor. 3. adjustment in cascade speed and position by the direct field orientation control induction motor (dfocim) one can proceed in the same way for the case where the speed regulation is made by the direct field orientation control fed in voltage, one adds in cascade, the loop of regulation of the position. the functional diagram of the loop of position is presented by figure 1 [12]. θε +− − ∗θ θ ω ωε s kk i p 3 3+ + θk rt∗ ∗ω rfjs + 1 s 1 p − + ω et∗ fig. 1.block diagram of position regulation. the transfer function in closed loop is: …(1) the cascade position, speed and torque impose a dynamics of very slow position compared to that speed. using matlb/simulink while basing oneself on the diagram block of figure 1 one can determine the gain of position 15=θk . the coefficients of speed regulator are given as follows 1790.43=pk 8550.193=ik 3)33(2)3(3 33 0)( )( ikkpkkipksppkrfjs ikkspkk rcs s θθ θθ θ θ +++++ + = = ∗ mohammed khalil hussain al-khwarizmi engineering journal, vol. 8, no.4, pp 9 -25 (2012) 11 4. complete order extended kalman filter (ekf) the extended kalman filter, allows the estimate of the state of a system extended to the speed. if one wants to estimate the load torque and the position of the rotor, a solution consists in extending the vector of state estimated with the load torque and the position of the rotor. the extended kalman filter in discrete time is given by the system of equation according to [13-15]     += ++=+ kk e k e k e kk e k e k e k e k e vxcy wubxax 1 …(2)          = ω +≈−ω= ω +ω+≈ω= − e k ee e e e k ee k e e e e e e e k e cc b tpa itbiapab tpa tpaitpaa ) 2 )( ()())(( 2 ))(( )())(exp( 77 1 2 7 …(3) when: [ ] [ ] [ ]      = = ωφφ= t ssk e t ssk e t rrrssk e iiy vvu tiix βα βα βαβα θ σ σ στ r ls=′ r r l mk = rrs rkrr .2+=σ r r r r l =τ rs ll m 2 1−=σ                                   −−           −φ     −φ      φ−ω φ−ω−− φ ′ − ′ ω ′ − ′ − φ ′ ω ′′′ − =ω 0010000 0000000 01 0010 0010 0010 0001 )( jj fik j pik j pk j pk j p pm pm r k r kp r k r kp r k r k pa srsrrrrr r rr r rr r r r rr r rr r r e αβαβ α β α σσσσσσσ β σσσσσσσ ττ ττ τττττ τττττ       = 0000010 0000001ec                           ′ ′ = 00 00 00 00 00 10 01 σσ σσ τ τ r r be the algorithm of ekf in complete order in discrete time is given as [16]: 1state estimate (prediction): k e kk e kk e kk e kk e ubxax //,/1 ˆ +=+ …(4) 2calculation of the covariance matrix of the error of prediction: k et kk e kk e kk e kk e qapap +=+ ,/,/1 …(5) 3calculation of the kalman filter gain (correction): ( ) 1 /1/11 − +++ += k t k e kk e k et k e kk e k e rcpccpk …(6) 4covariance matrix of the error of the filter (correction): ( ) kk e k e k e kk e pckip /1171/1 ++++ −= …(7) mohammed khalil hussain al-khwarizmi engineering journal, vol. 8, no.4, pp 9 -25 (2012) 12 5estimate of the vector of state at the moment (k+1) (correction): ( )kk e k e kk e kk e kk e xcykxx /111/11/1 ˆˆˆ ++++=++ −+ …(8) 5. reduced order extended kalman filter in practice, so certain exits of the system are measurable (stator currents), it is preferable to use them to reach directly in certain states and to estimate the others by the means of an observer of state of a reduced order. the advantage of such observer is that it makes it possible to reduce the synthesis of the observer in terms of establishment and also in terms of computing time [14] in order to obtain a simple model, we will adopt a model having rotor flux like state, the stator current like entry and the stator voltage like exit. the complex equations of the im can be rearranged in order to express rotor flux and the stator voltage, according to the components of the current and flux. in the stationary reference frame, we can write [17] ( ) ( )       +′+φ−ω= +φ−ω= φ s s rr r r s s r rr r r ir dt idrjpkv imjp dt d σ σ σττ τ τ τ τ 1 11 …(9)     ++= += ueducxy buaxx & & …(10) where: [ ] [ ] [ ]      = = φφ= t ss t ss t rr vvy iiu x βα βα βα             −ω ω−− = r r p p a τ τ 1 1             = r r m m b τ τ 0 0             −ω ω−− = r r r r r r kpk pkk c τ τ       = σ σ r r d 0 0       ′ ′ = σσ σσ τ τ r r e 0 0 the continuous model of a reduced order extended to the speed, the load torque and the position of the rotor are given by the system of equation according to: ( ) ( )    = = ee eee xhy uxfx ,& …(11) where: [ ] [ ]    = ωφφ= t ss e t rrr e iiu tx βα βα θ ( )             φ−ωφ ωφ−φ− = βα βα τ τ r r r rr re p p xh 1 1 ( )                       ω −−− +φ−ωφ +ωφ−φ− = 0 111 1 1 , rsrsr s r r r r s r rr r ee t jj fipk j ipk j imp imp uxf αβ ββα αβα ττ ττ             −′− −′− = βσ β σ σβ ασ α σ σα τ τ s s s s s s e ir dt di rv ir dt dirv y the reduced order ekf in discrete time can be obtained as follows [19]: ( ) ( )    = =+ k e k e k e k e k e xhy uxfx ,1 …(12) kf : the matrix of the discrete system is at every moment ritualized sampling by using the development in taylor series to the order two. the linearized model (13) is obtained, starting from the model extended in discrete times (12), by calculating jacobeans given by equation (14) [20]     = +=+ k e k e k e k e k e k e k e k e xcy ubxax 1 …(13) where: mohammed khalil hussain al-khwarizmi engineering journal, vol. 8, no.4, pp 9 -25 (2012) 13           = = = = = = k e k e k e k e k e k e xxe k k e xx k e k k e xxe k k e dx dhc du dfb dx dfa ˆ ˆ ˆ …(14) one applies the same of ekf algorithm describes previously to estimate the vector of state in reduced order ekf. 6. the block diagram of dfocim with complete order and reduced order ekf figures 2 and 3 represent the blocks diagrams of the dfocim in complete and reduced order ekf. in order to evaluate the performances of the algorithms of estimate by the ekf of a complete order then of a reduced order and consequently the performances of the systems of total drive, we subjected our systems to various tests of simulation, for a direct focim of speed and position. *ω * rφ ( ) ( )qsds srsrre rr sq s rrr r r s tiontransforma artg ,, 22 ˆˆ ˆˆˆˆˆ ˆ ˆ ˆ ˆˆˆ ˆ ˆˆ ι→ι ιφ−ιφρκ=τ φ ιμ +ρω= φ+φ=φ φ φ = βα αβαα βα β α τ ω θ ( ) ( )βα,, toqd αsv βsv αrφ̂ βrφ̂ αsι βsι ω̂ ω rφ̂ sω̂ eτ̂ sdι̂ sqι̂ ω̂ sdv∗ sqv∗ refsv α refv βα αsι̂ βsι̂ rt̂ θ̂ + − ∗θ θk sθ̂ fig. 2. block diagram of direct field orientation control induction motor (dfocim) with complete order extended kalman filter. *ω * rφ ( ) ( )qsds srsrre rr sq s rrr r r s iitiontransforma ii i artg ,, 22 ˆˆˆ ˆˆ ˆˆˆ ˆ ˆˆ → φ−φρκ=τ φ μ +ρω= φ+φ=φ φ φ = βα αβαα βα β α τ ω θ ( ) ( )βα,, toqd αsv βsv αrφ̂ βrφ̂ αsι βsι ω̂ ω rφ̂ sω̂ eτ̂ sdi sqi ω̂ sdv∗ sqv∗ refsv α refv βα rt̂ θ̂ + − ∗θ θk sθ̂ fig. 3. block diagram of direct field orientation control induction motor (dfocim) with reduced order extended kalman filter. mohammed khalil hussain al-khwarizmi engineering journal, vol. 8, no.4, pp 9 -25 (2012) 14 7. simulation results 7.a. simulation results in speed reference 1no-load response figure 4 represents the estimate of the model of rotor flux (reference flux 0.85 wb), position of the rotor, the speed and the torque as well as the estimation errors in the case of a no load for a level speed 1000tr/min. fig. 4. simulation results obtained with the two observers of kalman filter and error for a speed of reference 1000 tr/min (no-load). mohammed khalil hussain al-khwarizmi engineering journal, vol. 8, no.4, pp 9 -25 (2012) 15 2load response figure 5 represents the estimate of the model of rotor flux (reference flux 0.85 wb), the load torque, the position of the rotor, the speed and the torque as well as the estimation errors in the case of a no load starting for a level speed 1000tr/min followed of a level of the load torque 50nm at the time t=1 sec. to 3 sec. fig. 5. simulation results obtained with the two observers of kalman filter and error for a speed of reference 1000 tr/min (load of 50 nm at t=1s to 3s). mohammed khalil hussain al-khwarizmi engineering journal, vol. 8, no.4, pp 9 -25 (2012) 16 3no load tracking response figure 6 represents the estimate of model of rotor flux (reference flux 0.85 wb), the position of the rotor ,the speed and the load torque as well as the estimation errors in the case of a no load for a level speed 1000tr/min and an inversion of direction of rotation at the moment t = 2sec. fig. 6. simulation results obtained with the two observers of kalman filter (inversion of the direction of rotation of 1000 tr/min to -1000 tr/min to t=2s). mohammed khalil hussain al-khwarizmi engineering journal, vol. 8, no.4, pp 9 -25 (2012) 17 4load tracking response figure 7 represents the estimate of model of rotor flux (reference flux 0.85 wb), the load torque, the position of the rotor and the speed as well as the estimation errors in the case of a no load starting for a level speed 1000tr/min followed of a level of the load torque 50nm at the moment t=1 s, of an inversion of direction of rotation at the moment t = 2s and of a level of no load at the time t=3s. fig. 7. simulation results obtained with the two observers of kalman filter (inversion of the direction of rotation of 1000 tr/min to -1000 tr/min to t=2s and load 1 to 3 s). mohammed khalil hussain al-khwarizmi engineering journal, vol. 8, no.4, pp 9 -25 (2012) 18 according to the all above, one notes that the two observers of ekf express well still robustness the abrupt variation the speed of reference. the estimate of rotor flux, speed, load torque and position of the rotor is always made satisfactory way. the ekf in a complete order has a better stability than the ekf in reduced order. moreover, this stability can be felt at the time of the adjustment of the covariance matrices. indeed, the computing time for the methods of estimate which use the model of a complete order is largely more important than the time of estimate for the models of a reduced order. in more the errors in estimation obtained by the ekf of a reduced order always lower than those are obtained with the ekf in a complete order. 7.b. simulation results in position reference 1no-load response figure 8 represents the estimate of model of rotor flux(reference flux 0.85 wb), , position of the rotor, speed and the torque as well as the estimation errors in the case of a no load starting for an instruction of position in level ( o360=∗θ ). mohammed khalil hussain al-khwarizmi engineering journal, vol. 8, no.4, pp 9 -25 (2012) 19 fig. 8. simulation results obtained with the two observers of kalman filter and error for a position of reference o360=∗θ (no-load). 2load response figure 9 represents the estimate of model of rotor flux (reference flux 0.85 wb), the load torque, the position of the rotor, the speed and the torque as well as the estimation errors in the case of a no load starting for an instruction of position in level ( o360=∗θ ) follow-up of a level of the load torque 50nm at the time t=1s to 3 s. mohammed khalil hussain al-khwarizmi engineering journal, vol. 8, no.4, pp 9 -25 (2012) 20 fig. 9. simulation results obtained with the two observers of kalman filter and error for a position of reference o360=∗θ (load of 50 nm at t=1s to 3s). mohammed khalil hussain al-khwarizmi engineering journal, vol. 8, no.4, pp 9 -25 (2012) 21 3no load tracking response figure 10 represents the estimate of model of rotor flux (reference flux 0.85 wb), the position of the rotor ,speed and the load torque as well as the estimation errors in the case of a no load starting for an instruction of position in level ( o360=∗θ )follow-up of an inversion of instruction of position at the time t=2s . fig. 10. simulation results obtained with the two observers of kalman filter (inversion of the direction of position rotation of o360=∗θ to o360−=∗θ to t=2s) . mohammed khalil hussain al-khwarizmi engineering journal, vol. 8, no.4, pp 9 -25 (2012) 22 4load tracking response figure 11 represents the estimate of model of rotor flux (reference flux 0.85 wb), the load torque, the position of the rotor, the speed and the load torque as well as the estimation errors in the case of a no load starting for an instruction of position in level ( o360=∗θ ) follow-up of a level of the load torque 50nm at the time t=1s, of an inversion of instruction of position at the time t=2s and of a level of no load at the moment t=3s mohammed khalil hussain al-khwarizmi engineering journal, vol. 8, no.4, pp 9 -25 (2012) 23 fig. 11. simulation results obtained with the two observers of kalman filter (inversion of the direction of position rotation of o360=∗θ to o360−=∗θ to t=2s and load 1 to 3 s). according to the all above the response in position obtained with the reduced order ekf is better than that obtained with the complete order ekf. 8. conclusions for the two observers of kalman filter (order and reduced order ekf) , the simulation results obtained for the estimate speed and position are satisfactory from error in estimation point of view of robustness and stability of the system of total drive under any operating condition (no load, load ,tracking and tracking load) and a significant result is that the small estimation errors occurring during transient and steady state operation do not jeopardize the system performance but estimation error and time of state estimation in reduced order ekf in speed and position in all state is better than complete order ekf . however, one can say that the reduced order ekf involves a reduction of the computing time facilitating the establishment of the operation of observation on a device real time. appendix i the parameters im are listed in table (1). table 1, parameters of im. nominal power pn 7,5 kw nominal speed nω 1450 tr/min nominal torque t 50 nm number of pole paris p 2 p.u stator resistance sr 0,63 ω rotor resistance rr 0,4 ω stator inductance sl 0,097 h rotor inductance rl 0,091 h mutual inductance m 0.091 h moment of inertia j 0,22 kg.m2 mohammed khalil hussain al-khwarizmi engineering journal, vol. 8, no.4, pp 9 -25 (2012) 24 9. references [1] marcello montanari, sergei peresada and andrea tilli “observerless scheme for sensorless contorl of induction motor: stability analysis and designprocedure” proceedings of the 10th mediterranean conference on control and automation med2002 lisbon, portugal, july 9-12, 2002. [2] ezio bassi, francesco p. benzi, silverio bolognani, and giuseppe s. buja” a field orientation scheme for current-fed induction motor drives based on the torque angle closed-loop control” ieee transactions on industry applications, vol. 28, no. 5, september / october 1992 [3] joachim holtz “sensorless control of induction motors performance and limitations” ieee 2000 [4] murat barut ,o.seta bogosyan and metin gokasan “ekf based estimation for direct vector control of induction motors”ieee 2005 [5] murat barut ,seta bogosyan and metin gokasan “speed-sensorless estimation for induction motors using extended kalman filters” ieee transactions on industrial electronics, vol. 54, no. 1, february 2007 [6] américo vicente leite ,rui esteves araújo and diamantino freitas “a new approach for speed estimation in induction motor drives based on a reduced-order extended kalman filter” ieee 2005 [7] américo vicente leite ,rui esteves araújo and diamantino freitas “a real-time estimator of electrical parameters for vector controlled induction motor using a reduced order extended kalman filter”ieee 2006 [8] mickaël hilairet ,françois augerb and eric berthelot “speed and rotor flux estimation of induction machines using a two-stage extended kalman filter” science direct automatica 45 (2009) 1819_1827 . [9] murat barut “bi input-extended kalman filter based estimation technique for speedsensorless control of induction motors” science direct energy conversion and management 51 (2010) 2032–2040. [10] václav šmídl and zdenˇek peroutka “reduced-order square-root ekf for sensorless control of pmsm drives”ieee 2006. [11] s. kumar , j. prakash and p. kanagasabapathy “a critical evaluation and experimental verification of extended kalman filter, unscented kalman filter and neural state filter for state estimation of threephase induction motor” science direct applied soft computing 11 (2011) 3199–3208 [12] l. g. shiau, j. l. lin, "stability of slidingmode current control for high performance induction motor position drives," iee-proc-electr, vol 136, no. 6, pp 324-330, november 1989. [13] b. akin, "state estimation techniques for speed sensor less field oriented control of induction motors,". thesis of master, the middle east technical university, turkey, 2003 [14] m. barut, o. bogosyan, and m. gokasan, "an extended kalman filter based sensorless direct vector control of induction motors," ieee transpower electron, 2003. [15] t. o. kowalska, "application of extended luenberger observer for flux and rotor time-constant estimation in induction motor drives," iee-proc-electr, vol 148, no. 1, pp 69-75, january 2001. [16] dan simon "optimal state estimation kalman, ∞ η and nonlinear approaches" john wiley & sons, inc2006. [17] p. muraca' and c. picardi' “a reduced order extended kalman filter in induction motor drive ” 1993 ieee [18] mohinder s.grewal and angus p.andrews "kalman filtering :theory and practice using matlab " johon wiley & sons, inc 2001. [19] j. holtz, "the representation of ac machine dynamics by complex signal flow graphs," ieee trans. ind. electronics, vol 42, no. 3, june 1995, pp. 263-271. [20] m. barut, o. bogosyan, and m. gokasan, "an ekf based reduced order estimator for the sensor less control of im’s". ieee transpower electron, 2003. )2012(925 ، صفحة 4، العدد8مجلة الخوارزمي الھندسیة المجلد محمد خلیل حسین 25 تخمین السرعة والموقع لمسوق المحرك الحثي ذو سیطرة توجیة المجال المغناطیسي المباشر محمد خلیل حسین رئاسة جامعة بغداد/ قسم الشؤون الھندسیة mohammedkhalilhussain@yahoo.com : االلكتروني البرید الخالصة لمسوق المحرك الحثي بدون محسسات سرعة میكانیكیة في العمود للمحرك الحثي یتمتع بالكلفة dfoc)(سیطرة توجیھ المجال المغناطیسي المباشر في ھذا البحث .الستبدال المحسس بأخذ المعلومات عن سرعة والموقع للجزء الدوار یؤخذ من فولتیة وتیار الجزء الثابت للمحرك الحثي . القلیلة والثقة العالیة complete order and reduced order extended) ال المغناطیسي المباشر مع نوعین من مرشحات الكالمانتم تقدیم سیطرة توجیھ الج kalman filter) نتائج المحاكاه توضح االداء الجید ل . السرعة،العزم والموقع للمحرك الحثي ،لتخمن الفیض(reduced order extended kalman filter) على اداء(complete order extended kalman filter ) من حیث تتبع االداء وتخفیض وقت تخمین المعطیات. mailto:mohammedkhalilhussain@yahoo.com فاضل ومحمد وزينب al-khwarizmi engineering journal,vol. 12, no. physical and mechanical properties fadhil a. chyad* *,**,***department of (received abstract nanoferrite materials have been synthesized by sol percentages of y2o3 (0.34 µm) on the 0.9(co4fe2o4) 0.1] by adding 10% cobalt ferrite absorption) were affected by the doping, where drastically decreased about 80% at 6% strength and vickers microhardnss). the fracture strength at 1 % and then decreased. the same behavior shows with microscopy ) micrographs revealed that the microstructure of the fracture surface of the samples consist of detached approximately closely packed particles and also showed the formation of by doping with y2o3 the pores decreased and a dense material obtained keywords: nanoferrite, y2o3, density, splitting 1. introduction nano crystalline lithium ferrite has been investigated with last years due to its potential use in the microwaves field as a replacement for garnets or as a memory core [1, 2 important in construction and engineering of many electromagnetic and microwave lithium ferrite has been widely investigated material [2,3]. this material crystallizes in t spinal structure ab2o4, where a and b denote lattice site tetrahedrally and octahedrally coordinated by oxygen respectively[4] .lithium ferrite is an unusual and in the same respect, a remarkable material. where, several research programs have been undertaken to study its fundamental properties and to develop high-power microwave materials from it. distinctive properties of lithium ferrite are the following: 1the lithium ion is monovalent; i.e., in order to preserve charge balance, l��enters the lattice in combination with f��� ion. the compound may khwarizmi engineering journal,vol. 12, no. 2, p.p. 1017 (2016) mechanical properties of synthesized doped nanoferrite * mohammed s. hamza** zainab department of materials engineering/ university of technology *email: fchyad_2009@yahoo.de **email: dr.msh2013@yaho.com (received 26 june 2015; accepted 27 january 2016) nanoferrite materials have been synthesized by sol-gel auto combustion method. the effect of doping different ) on the physical and mechanical properties of selected mixed by adding 10% cobalt ferrite was studied. physical properties (i.e. .density, porosity doping, where the density increased about 32% at 6 wt% y y2o3 and has a correlation effect on the mechanical properties( the fracture strength at 1 % wt. of y2o3 has doubled value of the undoped sample same behavior shows with the testing of vickers micro hardness micrographs revealed that the microstructure of the fracture surface of the samples consist of detached approximately closely packed particles and also showed the formation of micro agglomerated the pores decreased and a dense material obtained splitting strength, vickers micro hardness. nano crystalline lithium ferrite has been investigated with last years due to its potential use field as a replacement for , 2]. due to its important in construction and engineering of many electromagnetic and microwave devices, lithium ferrite has been widely investigated material [2,3]. this material crystallizes in the where a and b denote lattice site tetrahedrally and octahedrally oxygen ions lithium ferrite is an unusual and in the same respect, a remarkable material. where, several research programs have been undertaken to study its fundamental properties and to develop power microwave materials from it. the hium ferrite are the the lithium ion is monovalent; i.e., in order to enters the lattice in ion. the compound may be thought of as (l��.�f�� can be prepared with low value of 2an ionic ordering can be established in lithium ferrite. lithium enters the spinel lattice on the octahedral sites (i.e., the spinel is inverted). the rare earth ions have unpaired 4f electrons that have a role to originate magnetic anisotropy due to their orbital shape crystalline anisotropy in ferrite in related to 4f coupling between the transition earth ions, thereby doping rare li-fe ferrite can improve their electrical and magnetic properties[5]. (2006), investigated the thermal decomposition of freeze dried li-mn (ii) precursor by differential thermal analysis thermal gravimetric analysis spectroscopy. it was found that the thermal decomposition of a homogeneous freeze lithium manganese tiron formats, followed by an annealing, is a suitable method for preparing a single phase solid solution ferrite (li o4, with 0 x 1), at relatively low temperature [6]. altavilla et al. (2009), have been studied the al-khwarizmi engineering journal (2016) synthesized doped nanoferrite zainab i. dhary*** technology method. the effect of doping different properties of selected mixed ferrite [(li2.5fe0.5) density, porosity and water y2o3, while porosity has a on the mechanical properties(splitting tensile has doubled value of the undoped sample micro hardness.sem ( scanning electron micrographs revealed that the microstructure of the fracture surface of the samples consist of detached agglomerated particles with some voids . �.�)fe2o4. lithium ferrite can be prepared with low value of ∆h. an ionic ordering can be established in lithium ferrite. lithium enters the spinel lattice on the octahedral sites (i.e., the spinel is inverted). the rare earth ions have unpaired 4f electrons role to originate magnetic anisotropy due to their orbital shape, where the magnetocrystalline anisotropy in ferrite in related to 4f-3d coupling between the transition metal and rare doping rare-earth into spinal prove their electrical and wende and langbein investigated the thermal decomposition of mn (ii)-fe (iii) formatted differential thermal analysis ( dta), thermal gravimetric analysis (tga) and mass spectroscopy. it was found that the thermal decomposition of a homogeneous freeze dried iron formats, followed by an annealing, is a suitable method for preparing a single phase solid solution ferrite (lixmn1-xfe2-2x 1), at relatively low temperature altavilla et al. (2009), have been studied the fadhil a. chyad al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 1017(2016) 11 synthesis of monodispersed fe2o4 (m=fe, co, ni) ferrite nanoparticles: effect of reaction temperature on the particle size. the possibility of preparing monodispersed transition metal-oxides nanoparticles covered by functionalized long chain organic molecules, in the sub size range of 20 nm, has recently opened an entire field of research [7]. de fazio et al. (2011), showed the electromagnetic properties of manganese-zinc ferrite with lithium substitution. polycrystalline manganese-zinc ferrite with lithium substitution of composition li0.5xmn0.4zn0.6-xfe2+ 0.5xo4 (0.0≤ x≤ 0.4) were prepared by the usual ceramic method [8]. arana et al. (2012) studied the lisubstituted mn-zn ferrite structural and magnetic properties after different thermal treatments. lithium of composition zn0.6mn0.4fe2o4 and li 0.2zn0.2mn0.4fe2.5o4 were prepared by the selfcombustion sol-gel method. incorporating li to the crystalline lattice increased the saturation magnetization and promoted a decrease in the secondary phase’s segregation [9]. rosaiah and hussien (2013) studied the preparation of the ferrite by hydrothermal synthesis. xrd spectrum exhibited predominate (200) orientation peak at 2θ = 43.63 corresponding to cubic structure. electric and dielectric properties were studied over a frequency range of 1hz-1mhz [10]. agami et. al. (2014), investigated the structural, ir, and magnetic studies of annealed li-ferrite nanoparticles nano-particles of spinel li-ferrite, li 0.5fe2.5o4, were prepared by sol-gel auto combustion technique and annealed at different temperatures (ta = 673, 873, and 1073 k)[11].the aim of this research is studding the physical and mechanical properties of synthesized nnoferrites doped by y2o3. 2. experimental work 2.1. sample preparation the numbers of samples and the percentage of y2o3 are listed in table (1). table 1, shows the numbers of samples and percentage of y2o3 2.1. preparation of nano-ferrite by coprecipitation 1. hydrated cobalt nitrate is dissolved in 50/50 % distilled water – ethanol ratio with 0.5(molarity) m. 2. hydrated lithium nitrate is dissolved in 50/50 % distilled water – ethanol ratio with 0.5 m. 3. hydrated iron nitrate is dissolved in 50/50 % distilled water – ethanol ratio with 0.5 m. 4. the cobalt solution is mixed with iron solution, where the ratio of cobalt solution to iron solution was selected according to a definite chemical stoichiometric ratio as (fe: co=2:1) by using magnetic stirrer. 5. the lithium solution is mixed with iron solution, where the ratio of lithium solution to iron solution was selected according to a definite chemical stoichiometric ratio as (fe: li =5:1) by using magnetic stirrer. 6. the two solutions are mixed by using magnetic stirrer. 7. 7. addition of the resulting cobalt ferrite with different weight percentage (2, 5, 10, 15 and 20 wt. %) to lithium ferrite. 8. addition of surfactant material (glucose). 9. addition of ammonium hydroxide drops to the mixed solution until the gel bed was formed. 10. ph of the solution was measured, where the gel formation begins at ph 6.5. 11. addition of citric acid that leads to hear notifying the combustion which helps in reducing the particle size of produced gel. 12. filtrate the solution with filter papers to get out the gel. 2.2. drying and calcination the filtered gel was then dried at temperature 80°c for 6 hours in a programmed electrical oven. the gel was then crushed and calcined at temperature 800°c at heating rate 10°c/min for 1 hour. the powders were finally cooled by switching off the furnace to room temperature. 2.3. powder compaction poly vinyl alcohol (pva) with 2 wt. % was mixed with the powder for (30) min. then, the powder was pressed unixally in stave stainless steel at (374) mpa pressure to have a compacted specimen with diameter (10mm) and thickness (4 mm). no. number of samples percentage of y2o3 1 3 0.5 2 3 1 3 3 2 4 3 4 5 3 6 fadhil a. chyad al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 1017(2016) 12 2.4. sintering process the sintering processes of the compact samples were carried out in air atmosphere. the sintering temperature used was 1200 °c for two hours, with a heating rate and cooling rate of 10°c/min as shown in the figure (1).then, the dimensions and masses of sintered samples were measured to determine apparent density , porosity and water absorption using archimedes method while splitting tensile strength measured by brazilian test and the micro hardness measured by vickers test . 3. results and discussion physical properties of doped nano-ferrite apparent density and porosity figure (2) presents the apparent density versus different weight percentages of y2o3. it has been shown that the apparent density of prepared nanoferrite samples is increased with increasing y2o3 content. this may be due to the removal of micro pores in their microstructure during the sintering process. during the sintering, the time of sintering and the temperature are very important parameters to satisfy the diffusion of particles and then increasing mass flow rate through the pores which leads to increase the apparent density and decrease the porosity, as shown in figure (2). sintering at high temperature causes high diffusion rates and higher densification. fig. 1. single heating cycle of the applied sintering process. fig. 2. density for ferrites at different percentages of y2o3. figure (3) shows the effect of y2o3 addition on the porosity of ferrite system sintered at 1200⁰c for two hours. as seen the porosity decreased rapidly with increasing the y2o3 content which may be due to the filling of the pores, which gives higher densification as shown in the density results. fig. 3. apparent porosity for different percentages of y2o3. water absorption water absorption is shown in figure (4) for different weight percentages of y2o3. the water absorption decareases with increasing the precentage of y2o3. it is well known that the water absorption is the physical property upon that dopends on the appearent porosity, where the water enters the open pore channel. fadhil a. chyad al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 1017(2016) 13 fig. 4. water absorption for different weight percentages of y2o3. 4. mechanical properties splitting tensile strength (brazilian test) figure (5) shows the effect of y2o3 percentages on the fracture strength of nanoferrite which is sintered at 1200℃ for two hours. it is clear a bell shape formed from the relation between y2o3 percentage and fracture strength of the nano-ferrite which increased with increasing the y2o3 content having the highest value (51 mpa) at 1wt. % y2o3 and then decreased. as shown in the figure that the addition of y2o3, especially at 1wt. % has highly improved the splitting tensile strength of the ferrite system, its value is more than twice that of the ferrite system. the increasing in the splitting tensile strength of the doped ferrite is due to density improvement with less porosity which leads to increasing the particles bonding. after 1wt. % y2o3, the fracture strength decreases with further addition of y2o3, and this may be due to the presence of residual porosity in the ferrite system. residual stresses in the samples are another factor that may have contributed to the reduction in splitting tensile strength [12]. there is a difference in the thermal expansion coefficient between ferrites and y2o3, and this mismatch in the thermal expansion coefficient could produce residual stresses near ferrites-y2o3 grain boundaries. and, that could also result in micro cracking which lowers the strength values [13]. fig. 5. the splitting tensile strength of nano-ferrite at different percentages ofy2o3 sintered at 1200⁰c for 2 hrs. vickers micro hardness the micro hardness of material is an important mechanical property because it relates how much the material will inelastic deformed when a surface load is applied. the indentation diameters of micro vickers tester for sintered samples are very small and do not appear in vickers tester instrument. the light optical microscope with a computer program was used to analyze the image and calculate the micro hardness. the vickers micro hardness value of the ferrite system doped with different percentages of y2o3 that sintered at 1200⁰ c for 2 hrs is shown in figure (6). it is clear that the hardness of samples increased with increasing y2o3 content until 1wt. % and then decreased while has the same behavior of splitting tensile strength. because the hardness value are highly correlated with the relative density and porosity, so reducing the number of defects in a sample is a common way of decreasing its micro hardness[14]. the hardness has a maximum value at 1 wt.% y2o3 which will result in a material being more resistance to the indentation at a given load, which will signify that the material will be able to plastically deform more so than the ferrite ceramic. sometimes, the mechanical properties, such as hardness are decreased when the grain size is decreased in the nano range, as reported by andrievski and glezer [15]. furthermore, in this work, vickers micro hardness is decreased slightly after 1% y2o3. fadhil a. chyad al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 1017(2016) 14 fig. 6. vickers micro hardness for the different percentages of y2o3. 5. sem of doped nano-ferrites sem imaging was conducting to observe the shape and morphology of samples. the sem micrographs were taken from the fresh fracture surface of a ferrite body compacted and sintered at 1200⁰ c from the composition [(li0.5fe2.5o4)1x(cofe2o4)x]1-y(y2o3)y obtained with the classical ceramic technology presented. these micrographs are shown in figure (7) to figure (11) . it is clear that the fracture surface is an intergranular fracture (equiaxal), and the microstructure displays an irregular (nonequiaxal) fine grain microstructure with average grain size that are slightly larger than the ferrite powders particle size. it is evident from the micrographs that the microstructure of the surface consists of detached, approximately closely-packed particles. also, these images show the formation of micro agglomeration particles and some voids, where pores are located at the junctions of agglomerates. the black and dark regions correspond to the ferrites particles and pores respectively, while the lighter areas are for y2o3 phase. furthermore, it is clear that by increasing y2o3, the porosity decreased and denser materials obtained. the crack propagation occurs near the pores in the microstructure, where the pores act as stress density resulting in easy crack propagation path. it is also clear that some of the grains have grown when the sintering at 1200℃ in the preferred orientation. the fracture nature of the prepared nano-ferrite from lithium ferrite-10% cobalt ferrite – y2o3 seems to be brittle which is clear from the fracture samples after the indirect tensile test (brazilian test). fig. 7. sem image of fracture surface for 0.5% y2o3 additives. fig. 8. sem image of fracture surface for 1% y2o3 additives. fig. 9. sem image of fracture surface for 2% y2o3 additives. fadhil a. chyad al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 1017(2016) 15 fig. 10. sem image of fracture surface for 4% y2o3 additives. fig. 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[15] r. andrievski and a. glezer, “size effects in properties of nanomaterials ”, elsevier science ltd., vol. 44, pp (1621-1624), 2001. �� ا ��� ��اد ��ل �ط�� ��� )2016( 1017، ���� 2، ا ��د���12� ا ��ارز�� ا 17 ��� ��ي ا�� ��!ا � ا ��"���"� �$�� وا %�� درا � ا ��اص ا �د�� ���' ()�***ز �2 ا�01�ج (�ري ** �� � �.ب , %ة* * ��/ ا���اد ��� ھ����***،**،*������ �ا�$#"!� ا .defchyad_2009@yahoo: ا�+)*� ا(�� )و&%* dr.msh2013@yaho.com : ا�+)*� ا(�� )و&% ** ��.� ا �5 –ا���ل ( "�اد ا�3)ا*2 ا��#&�*� 01)*/� .-)ت ��)*# ذو .$� .+�+% �7 درا�� 7>;�) ا:#�9 وذا7�� ا(. )اق ) ��) ٠.٣٤(&�a "@ ?�3 "< ا f�3��?3)ا*2"#*�)ون h?i ا�@�اص ا ����&#������ واk#* (-l��li)]ا 2.5fe0.5)0.9(co4fe2o4)0.1] . 5m" ��k#*f�3��� ( ان ا�@�اص ا"#���ا��m#�9 وا �� ا��#ء o#p "اص ) وا�@��) h?i ا;<7 #q� % ��)ة وا+s رة�p1 2p?/7 �/9 ��"#����u ازدادت ا��f1 �9#m*#دة &�a ا(:#�9 ا"# ا. #*(� ��7>;)ت 1#:#�9 ا 5m" ����&#�����)*# %)١(��+� 23i#-7 " #&� ا���) ��i 1) . " #&� ا��w وvoدة 9��)ز ( ا ��&3] ا� p)ف ��i .�#ب voدة . و"< ;� 2p�#�7 "< ا �^ 7��*< د�#k[ ظا .9��)ز_sو �oت " $#ورة " )ا#+�+. h?i #+*(/7 ي� l* ذج#��?� (����a ا��$q)ي ��b0 اs( �q)ت �oر ا(�� )و&% ا��#�b 1>ن ا �)*# �?2 ا��� وc" .�!1 و��د 9$�ات �"#*�)و*� " $�! ��ً 7)اoاms) ا��plل h?i "#دة و�7 #"#ت1#:#�9 ا #. 6171 al-khwarizmi engineering journal,vol. 12, no. 3, p.p. 6 experimental simulation of finned vertical department of mechanical engineering / (received 20 dec ___________________________________________________________________________ abstract in this work an experimental simulation along heated finned vertical base plate two types of fin arrays namely vertical fin heights and spaces. the influence of inc parameters such as fin height and fin spacing and average nusselt number have been between average nusselt number versus rayleigh number that the configuration of v-fins array coefficient about 20% greater compare present work are compared with a previous works keywords: natural-convection, experimental _______________________________________________________________________ 1. introduction the configurations of fins and inclinations play an important role in natural-convective transfer. fins and fin arrays are extended surfaces used to enhance and increase heat transfer rate and heat dissipation from heated surfaces to the surroundings in electronic devices and engineering applications. many configurations of fin arrays like vertical fins, tri trapezoidal fins, tree-shaped fins , pin fins ,v shaped and v-shaped with bottom spacing. arrays on vertical base plates of various shapes are of great importance in industrial applications as cooling of the electronic and micro equipments , high voltage power transformers motors, high power chips, nuclear reactor cores , compact heat exchangers , radiators the houses , energy storage system and collectors . churchill and chu [1] deduced correlation to predict the nusselt number khwarizmi engineering journal,vol. 12, no. 3, p.p. 6171 (2016) simulation of natural heat convection vertical plate with different inclinations saad najeeb shehab engineering / college of engineering /al-mustansiriayah e-mail: saad_najeeb16@ yahoo.com eceived 20 december 2015; accepted 14 april 2016) ___________________________________________________________________________ simulation is made to predict the performance of steady-state plate to ambient air with different inclination angles and config vertical fins array and v-fins array on heated vertical base pl of inclination angle of the plate , configuration of fins spacing on the temperature distribution, base convection have been plotted and discussed. the experimental data are correlated to a formula versus rayleigh number for vertical plate and vertical fins array gave best natural-convection heat transfer performance compared with vertical fins array. experimental simulation data and correlations previous works shows good agreement. xperimental simulation, finned plate, fins array. _______________________________________________________________________ configurations of fins and inclinations convective heat fins and fin arrays are extended surfaces used to enhance and increase heat transfer rate and heat dissipation from heated surfaces to the surroundings in electronic devices and engineering applications. many configurations of triangular fins, shaped fins , pin fins ,vshaped with bottom spacing. fin s of various shapes are applications such and microelectronic high voltage power transformers , nuclear reactor cores , radiators, heating of , energy storage system and solar deduced an empirical nusselt number for steady-state free-convection heat transfer from vertically heated base plate turbulent flow conditions baudoin [2] obtained th convection heat transfer and inclined flat plate after several experiments they measured the temperatures by u (ir) thermography. the results show that the increase in convection heat transfer coefficient about 10% when roughness elements used than flat surfaces. rao et al. numerically the combined free radiation heat transfer from vertical plate with fins array. they solved the governing equations alternate direct implicit (adi) method. noted that the convection heat transfer rate increasing with fin spacing decreases and fin length increases. abid [4] the effects of fin shape on convection. he used vertical and pin fins array and developed empirical correlation fins and pin fins array in laminar condition sable et al. [5] investigated al-khwarizmi engineering journal (2016) convection from inclinations mustansiriayah university _______________________________________________________________________________________ state natural heat convection configurations of fin array. late are used with different array and fin geometrical convection heat transfer coefficient data are correlated to a formula for vertical plate and vertical fins array. the results indicate performance as base heat transfer data and correlations of the ____________________________________________________________________________________ convection heat transfer from plate in a laminar and conditions .vermeulen and the experimental freeconvection heat transfer correlations for vertical and inclined flat plate after several experiments. the temperatures by using infrared (ir) thermography. the results show that the increase in convection heat transfer coefficient of about 10% when roughness elements (fins) are rao et al. [3] investigated numerically the combined free-convection and radiation heat transfer from vertical plate with fins governing equations using direct implicit (adi) method. they noted that the convection heat transfer rate increasing with fin spacing decreases and fin ] studied experimentally fin shape on laminar natural vertical and pin fins array and developed empirical correlations for vertical and pin fins array in laminar condition flow. ] investigated enhancement of freesaad najeeb shehab al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 6171 (2016) 62 convection heat transfer on heated vertical plate by multiple v-fins array. the results show that the v-fins array gave better heat transfer performance than vertical fins array and v-fins with bottom spacing array. naidu et al. [6] studied the problem of natural convection experimentally and numerically by using alternate direct implicit (adi) method from fin arrays with different inclination angles of two geometric orientations, vertical and horizontal fins array. the results show that the convection heat transfer rate of vertical fins array is great than horizontal fins array for the same inclinations angles. fahiminia et al. [7] presented computational analysis of the natural-convection on extended vertical base surfaces by using finite volume method (fvm). they concluded that the heat convection rates increases with increasing fin space reaches to optimum spacing . more et al. [8] presented review study of natural-convection from heated plate with different configurations of the fin arrays and inclinations. the results of study show that the all configurations of fin arrays are improved thermal design and heat dissipation rate of the heated surfaces with different percentages. hireholi et al. [9] investigated experimentally and theoretically the heat transfer by free-convection of heat sink used for cooling of the electronic chips. they found the optimum fin spacing. they compared that the experimentally measured temperatures of heat sink with theoretically predicted temperatures using two-dimensional model and show a very good agreement. tiwari and malhotra [10] studied heat transfer of laminar natural-convection over a flat plate bounded by enclosures with effects of the surface roughness , ambient temperature , flow velocity and surface inclinations on the convection heat transfer coefficient at different heat source input. they noted that the increase in heat source input increases the heat transfer rates and the increase in surface inclination decreases the heat transfer coefficient. the present work concentrates experimentally on the effects of configuration of fins array, base plate inclinations (ϕ), fin height (h) and fin spacing (s) on performance of natural-convection heat transfer over a heated vertical base plate. this is assist to predict of the temperatures distribution along a vertical heated base plate and to calculate convection heat transfer coefficient with and without fin arrays to choose the best configuration and design of fins array. 2. experimental work 2.1. experimental rig the experimental test rig and it’s components shown in fig. 1 consists of an aluminum square base plate of 200 mm side has thickness 2.0 mm. vertical plate and two configurations of fin arrays vertical fins and v-fins are joined on the base plate are tested as shown in fig. 2 with different fin height (h) and fin spacing (s) having thickness 2.0 mm. the vertical base plate is heated from backside using an electrical heater wire is coiled around mica sheet and then is sandwiched between two symmetrical square sheets of mica with same dimensions of the base plate and thickness of 0.5 mm to obtain homogeneous heating of the base plate and ensured the electrical insulation of heater wire. it’s fixed on the backside of base plate by thermal super glue. the backside of base plate assembly is a good insulation using polyurethane foam layer with 60 mm thickness to minimize the conduction heat loss. also the sides are framed by plywood frame. the whole assembly of base plate is fixed in a vertical position with an adjustable support allowing different angles of inclination in a square enclosure constructed of cast acrylic sheet of thickness 6 mm, with dimensions (500 mm length × 500 mm width × 600 mm height) opened from upper and lower ends under guaranteed a good free-convection heat transfer conditions. the inclination angles of base plate are measured with vertical position by a fixed protractor. the heating element is supplied up to 300 w with stabilized alternating current (ac) and voltage of 220 v through a contact type voltage regulator with digital reader type sako-tdgc2 to control on the electrical heat input and digital multi-meter type victor-vc890c+ to measure voltage and current. twelve k-type calibrated thermo-couples are embedded at different suitable locations in back surface of the vertical base plate to measure surface temperatures. they are matrix form distributed (4 rows × 3 columns) with equal distances. the thermocouples are connected to twelve channels digital temperature recorder type btm-4208sd. another two same k-type calibrated thermocouples are joined in digital multi-meter to record temperatures difference to evaluate the conduction heat loss from the backside of heated base plate. additional two separate k-type digital calibrated thermocouples are used to measure the ambient temperature inside the enclosure. saad najeeb shehab al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 6171 (2016) 63 a. front photo b. side photo 1. opened enclosure 2. finned plate assembly. 3. digital temperature recorder. 4. thermocouple wires. 5. adjustable support. 6. protractor. 7. voltage regulator. 8. digital multi-meter. fig. 1. photos of the experimental rig. a. vertical plate b. vertical fins array c. v-fins array fig. 2. tested vertical plate and fin arrays configurations. 2.2. experimental procedure and calculations three cases are studied , vertical base plate , vertical base plate with vertical fins array and vertical base plate with v-fins array. three angles of inclination with respect to vertical position are used (ϕ= 15o , 30o and 45o). cases of fin arrays is carried out for different fin height (h= 15 , 30 and 45 mm) and fin spacing (s= 14.5 , 20 , 31 and 64 mm) depending on numbers of fins as table 1. multirange of the electrical heater input wattage namely 25 , 50 , 75 , 100 , 125 and 150 w are used. all readings of the temperatures are recorded under steady-state conditions every 45 minutes approximately and when varying of the temperature readings less than 0.5 oc. table 1, number of fins against fin spacing in fins array. number of fins, n 4 7 10 13 fin spacing (s), mm 64 31 20 14.5 the electrical heat input (qin) to the heating element is : ��� = � � … (1) it's transferred to the ambient mainly by naturalconvection (qc) in addition to radiation (qr) and conduction (qcd) heat transfer losses. then, the rate of natural-convection heat transfe (qc) can be evaluated as : � = � � − �� − � � … (2) the radiation heat transfer rate (qr) is [11] : �� = �����(����� − ���) … (3) the conduction heat transfer rate (qcd) is calculated by fourier’s equation as [11,12] : saad najeeb shehab al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 6171 (2016) 64 � � = � ��� ∆� … (4) the radiation heat transfer (qr) from the heated base plate and fins array is small because the emissivity (ε) of bright rolled aluminum used in manufacturing the base plate and fins is 0.04 and it’s found to be less than 5% of electrical heat input (qin) for all cases. the loss by heat conduction (qcd) is minimized using a thick layer of polyurethane foam with very low of thermal conductivity about 0.028 w/m.k . it’s found to be approximately 2% of heat input (qin) . according to newton’s law of cooling, the net heat transfer from the base heated plate by natural-convection is expressed as [11] : � = ℎ���(���� − ����) … (5) hence, the base convection heat transfer coefficient (hb) is : ℎ� = � � − (�� + � �)��(���� − ����) … (6) and the average convection heat transfer coefficient (hav) can be evaluated as follows : ℎ�� = � � − (�� + � �)�&(���� − ����) … (7) the total surface area of free-convection heat transfer (at) for vertical fins array is : �& = (�� –*+,+ 2*.+ … (8) and for v-fins array is : �& = (�� – , ∑ +1� 2�34 + 2.∑ +1�2�34 … (9) where , lv is the length of v-fin. the average nusselt number (nu89) at the heated plate is computed by [11,12]: nu89 = h89l<k … (10) the average grashof number (grav) can be defined as follows [11,12] : ?@�� = abcdefgd hc@gijkljgcbj hc@gij= mngcjo(���� − ����)+ pqr … (11) define rayleigh number (ra) as the product of the grashof and prandtl numbers [11] : se = ?@�� t@ … (12) the average surface temperature (tsav) is: ���� =u ��f� �34 … (13) and the average of ambient temperature (taav) is sum of two readings of ambient temperatures inside an enclosure (ta1) and (ta2) divided by two to obtained a more accuracy : ���� = ��4 + ��r2 … (14) all properties of air are taken at film temperature (tf) : �v = w���� + ����2 x + 273.18 … (15) where, lc is the characteristics length of geometry , lc= l for vertical base plate, lc= s for vertical fins array and v-fins array configurations [11,12] . 3. results analysis and discussion the utilized empirical correlations for comparison with the experimental average nusselt number (nuav) of natural-convection heat transfer over heated vertical plate under steady-state and laminar flow conditions are listed in table 2 . table 2, available empirical correlations. empirical correlation expression with limitations mcadam’s [11, 13] *b�� = 0.59 (se)z.r[ … (16) ( 10 4< ra <109 ) churchill and chu’s (first relation) [1,11] *b�� = \0.825 + 0.387se4/^ {1 + `0.492t@ ab/4^}d/ref r … (17) ( 10 -1< ra <1012 ) churchill and chu’s (second relation) [1,11] *b�� = 0.68 + 0.67se4/� {1 + `0.492t@ ab/4^}�/b … (18) ( 10 -1< ra <109 ) churchill and usagi’s [11] *b�� = 0.67se4/� {1 + `0.492t@ ab/4^}�/b … (19) ( 10 5< ra <109 ) saad najeeb shehab al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 6171 (2016) 65 also the experimental simulation data of laminar natural heat convection from vertical fins array case are compared with empirical correlation of abid [4] : *b�� = 0.045(se′)z.e[ … (20) where , se′ = se wg+x … (21) variation of the base convection heat transfer coefficient (hb) with average surface temperature (tsav) for vertical base plate , vertical fins and vfins array at fin heights (h) ranging (from 15 to 45 mm) and spacing (s= 64 mm) are shown in figures (3) and (4). the values of base convection heat transfer coefficient (hb) in v-fins array are greater than vertical fins array case because of created a low pressure suction region in the corners of v-shaped fins on the down-stream side of v-fins therefore , the cold air flows into the separation region. it’s caused to increase the base convection heat transfer coefficient (hb) and the heat dissipation rate. figures (5-7) show variation in the base convection heat transfer coefficient (hb) with inclination angle (ϕ) at heat input ranging from 25 w to 150 w when fin height (h= 30 mm) and spacing (s= 64 mm) for vertical base plate , vertical fins and v-fins array respectively. as the fin height (h) increased , the average surface temperature (tsav) decreased because a more of cold air enters between fins and the base convection heat transfer coefficient (hb) increased . in general, the base heat transfer coefficient (hb) decreases with inclinations (ϕ) increasing and heat input decreasing. figures (8) and (9) illustrate variation in the base convective heat transfer coefficient (hb) with fin spacing (s) at different fin height (h) while heat input kept at 100 w for vertical fins and vfins array respectively . the convection heat transfer coefficient (hb) as a function of fin spacing at first increases up to a peak value with fin spacing (s) increasing and then decreases gradually because the average surface temperature (tsav) decreases down to a minimum with fin spacing (s) increasing and then increases gradually as shown in figures (10) and (11). the optimum fin spacing (soptimum) value maximizing base convection heat transfer coefficient (hb) and minimizing average surface temperature (tsav) for all three fin height is about 20 mm for vertical fins and v-fins array configurations. the experimental simulation data are correlated to a formula between average nusselt number (nuav) versus rayleigh number (ra) for vertical plate and vertical fins array and compared with a previous works for same conditions as shown in figures (12-14). a correlation is suggested to predict the average nusselt number for vertical plate : nu89 = 0.563 (ra)z.r[ … (22) for (4.3×106 < ra < 4×107) . the squared correlation coefficients (r2= 94.5%). the absolute percentage relative of error between suggested correlation and experimental data is (e ≤ 11%). another experimental correlation is adopted for vertical fins array at optimum fin spacing ( soptimum= 20 mm ) and fin height (h= 15 mm) : nu89 = 0.0523 `ra׳az.e[ … (23) for (780 < ra 2460 >׳) . the squared correlation coefficients (r2= 99%) , the absolute percentage relative of error between suggested correlation and experimental data is (e < 3.5%). the relative error between the suggested correlation of vertical plate with other correlations is (e < 10%). the agreement of present work is very good especially with mcadam’s correlation (e < 5.5%), also the relative error between the suggested correlation of vertical fins array with abid correlation is (e < 15%) at same conditions according to the figures (13) and (14) . fig. 3. base convection heat-transfer coefficient versus average surface temperature for vertical plate and vertical fins array. saad najeeb shehab al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 6171 (2016) 66 fig. 4. base heat transfer coefficient versus average surface temperature for vertical plate and v-fins array. fig. 5. base heat transfer coefficient versus inclination angle for vertical plate. fig. 6. base heat transfer coefficient versus inclination angle for vertical fins array. fig. 7. base heat transfer coefficient versus inclination angle for v-fins array. saad najeeb shehab al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 6171 (2016) 67 fig. 8. base heat transfer coefficient versus fin spacing for vertical fins array. fig. 9. base heat transfer coefficient versus fin spacing for v-fins array. fig. 10. average surface temperature versus fin spacing for vertical fins array. fig. 11. average surface temperature versus fin spacing for v-fins array. saad najeeb shehab al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 6171 (2016) 68 fig. 12. analysis of the experimental simulation data of present work for vertical base plate to the power function fits. fig. 13. comparison of average nusselt numbers ( nuav ) for vertical base plate with available empirical correlations . fig. 14. experimental simulation data of present work for vertical fins array compared with abid correlation. saad najeeb shehab al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 6171 (2016) 69 4. conclusions natural-convective heat transfer from the heated vertical base plate, vertical fins array and v-shaped fins array are studied experimentally and focused on the determination of the geometrical configuration giving the best naturalconvection heat transfer performance. the following conclusions can be drawn: 1the type of v-fins array gave better convection heat transfer performance in term of base convection heat transfer coefficient about 20% bigger compared than vertical fins array. 2as the height of fin increased, the average surface temperature decreased and the base convection heat transfer coefficient increased. 3the base convection heat transfer coefficient decreases with inclinations increasing and heat input decreasing. 4the optimum value of fin spacing is about 20 mm for vertical fins and v-fins arrays when maximizing base convection heat transfer coefficient. 5experimental correlations are suggested to predict the average nusselt number for vertical plate and vertical fins array. nomenclature ab base area, (m2) as surface area of heat transfer, (m2) at total surface area of convection heat transfer from fin-arrays, (m2) f radiation shape factor, (--) g gravitational acceleration, (m/s2) gr grashof number, (--) h convection heat-transfer coefficient, (w/m2.k) h fin height, (m) i input current intensity, (a) k thermal conductivity of material, (w/m.k) l length / height of vertical plate or fins array, (m) lc the characteristics length of geometry, (m) n number of fins, (--) nu nusselt number, (--) pr prandtl number, (--) qc convection heat transfer rate, (w) ra rayleigh number, (--) ra׳ modified rayleigh number, (--) s fin spacing, (m) t fin thickness, (m) ta ambient temperature, (oc) ts surface temperature, (oc) ∆t temperature difference, (oc) v voltage supplied, (v) x thickness, (m) greek letters β volumetric coefficient of thermal expansion, (1/k) ε emissivity of the surface, (--) ϑ kinematic viscosity of the air, (m2/s) σ stefan-boltzmann constant , (σ = 5.67 × 10-8 w/ m2.k4) ϕ inclination angle of the plate with vertical position, (deg) subscript symbols av average b base 5. references [1] churchill, s.w. and chu, h. h. s. “correlating equation for laminar and turbulent free convection from a vertical plate “ , international journal of heat and mass transfer , vol. 18 , pp. 1323-1329 , 1975 . [2] vermeulen, j.p. and baudoin , p. “ study of free convection by infrared thermography over a constant heat-flux heated plate “ , eurotherm series 27-eeti edition , paris, 1992 . [3] rao, v.d. , naidu , s.v. , roa. b.g. and sharma , k.v. “combined convection and radiation heat transfer from a fin array with a vertical base and horizontal fins”, proceedings of the world congress on engineering and computer science wcecs , san francisco, usa, october 2007 . [4] abid , w. m. “study of fins shape efects on natural thermal convection “, journal of alqadisyia for engineering sciences, vol. 2, no. 2 , 2009 . [5] sable, m.j., jagtap, s.j. , patil, p.s., baviskar , p.r. and barve , s.b. ”enhancement of natural convection heat transfer on vertical heated plate by multiple vfin array” , ijrras , vol. 5 (no. 2) , nov. 2010 . [6] naidu, s.v., rao, v.d., roa, b.g., sombabu, a. and sreenivasulu, b. “ natural saad najeeb shehab al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 6171 (2016) 70 convection heat transfer from fin arrays experimental and theoretical study on effect of inclination of base on heat transfer “, arpn journal of engineering and applied sciences , vol. 5 , no. 9 , sep. 2010 . [7] fahiminia, m. , naserian, m.m. , goshyeshi, h.r. and majidian, d. “investigation of natural convection heat transfer coefficient on extended vertical base plates “ , j. of energy and power engineering, vol. 3, pp. 174-180 , 2011 . [8] more, r.s. , mehta, r.i. and kakade, v.a. “ review study of natural convection heat transfer on heated plate by different types of fin array “ , international journal of engineering sciences and research technology , 2 (12) , dec. 2013. [9] hireholi, s. , shekhar , k.s.s. and milton , g.s. “ experimental and theoretical study of heat transfer by natural convection of a heat sink used for cooling of electronic chip “ , international journal of engineering inventions ,vol. 2, issue 2, pp. 01-09 , jan. 2013. [10] tiwari, p. and malhotra, v. “natural convection over a flat plate from side to side enclosures “ , international journal of application or innovation in engineering and management, vol. 3 , issue 2 , feb. 2014 . [11] lienhard, j.h. “a heat transfer textbook“ , phlogiston press, 3rd edition , usa, 2008. [12] long, c. and sayma, n. “heat transfer”, ventus publishing , 1st edition , london, 2009. [13] mcadams, w.h. “heat transmission “ , mcgraw-hill, new york, 1954. ��� ���ب�� ��� 3ا�� د ،12 ��� ا���ارز � ا��� ��� ا����� ،71 -61 )2016( 71 ����� �� �ة ����! ���د"� ����� # ����) ا��'اري ا�%$��� ���)� (� +!وا"� ��� ���ب �� �� ا������ ا���������� ���� ا������ / � /� !"�#� ا�&�%$� ا�� saad_najeeb16@ yahoo.com: ا�(! � ا���#!و�' _______________________________________________________________________________________________ � �ـا��, %�58�3d و %�d> ��e5وا �5 5�%= ��#�(b> cداء أ�#;�ل ا�+!ارة <��+�= ا�>(�$' .' ا�+��� ا���#;!ة %: �89+� 7�3د �5 %+���ة �3��� أ1! 0 ،.' ھ,ا ا�(+* �8�#e% ل��fg�8 ا�#e% h��3ا�$�7د �5 .و789ف ز h��53dھ��5 %"785.� ا� ��e5�3�k5 ا�"�85+� ا�$�7د �5 ا�� h��53d�8ن %: 7859ف ا��#e% نm�f م�e#أ� �v �558-و%"7855.� ا�h��553d �755ع#e% �55���> �55.�ت�زاو �55 %�55= ا�"�855+� ا��$����55 و�55f= %"7855.� ا�55q h��553dـ� درا��rb55q �55! �55= %55: . و<bر�553�8qت و% 5�0 ا��#�x!ات ا������� �� �8�3d�bر�8qع ا��8�3d وا����.� <�: ز�8�3 وأw!ى 3�k ا�#7ز u ا�+!اري و %$�%= أ�#;�ل ا�+5!ارة <��+�5= و %$�5ل و��� �5��5q .ر y���0 ور�� ر �� ����ت q&! (�� %: ا�(����ت ا�$���� <�: %$�ل رm3 kا�$�7 ا�#97= ا� h��3d�8+� ا�$�7د � و%"78.� ا�"�<��0 ا��#�5\] أداء أ.5z= . د �� ��q [\�5# %;�ر��5 .%;�ر�� <�"78.� ا�h��3d ا�$�7د � %20و%$�%= أ�#;�ل [!ارة أ�(! <+�ود �g-v#;�ل ا�+!ارة <��+�= ا�>(�$' ��"78.� ا�h��3d �7ع ��ت ا�#&! (�� ��(+* ا��;�م %u <+7ث ��<;� و��ن ا�#7ا.^ ��1 m$و ا� ��� . ا��+���ة ا�$� <4d6963726f736f667420576f7264202d2037342d20383220e3cde3cf2020e6c7d3c7e3c920ddc7d6e1> al-khwarizmi engineering journal al-khwarizmi engineering journal,vol. 13, no. 3, p.p. 7482 (2017) modeling of monocrystalline pv cell considering ambient conditions in baghdad city mohammed e. abd al-wahed* osamah f. abdullateef** * department of energy engineering/ college of engineering / baghdad university ** department of automated manufacturing engineering/al-khwarizmi college of engineering / baghdad university *email: mohammed.alwahed@yahoo.com **email: drosamah65@gmail.com (received 7 november 2016; accepted 22 february 2017) https://doi.org/10.22153/kej.2017.02.002 abstract the environmental conditions are important factors, because they affect both the efficiency of a photovoltaic module and the energy load. this research was carried out experimentally and modeling was done in matlab –simulink by monitoring the variation in power output of the system with environmental conditions such as solar radiation, ambient temperature, wind speed, and humidity of baghdad city. from the results, the ambient temperatures are inversely proportional to humidity and the output power performance of the system, while the wind speed is directly proportional with the output power performance of the system. keywords: ambient temperature, cell temperature, humidity, photovoltaic, solar radiation, wind speed. 1. introduction solar energy has the greatest potential of all the sources of renewable energy. if only a small amount of this form of energy could be used, it will be one of the most important supplies of energy specially when other sources in the country have depleted energy comes to the earth from the sun. the use of solar energy for electrical power generation dates back to space age when solar photo voltaic cells were used to power satellites orbiting around the earth. with passing time it was realized that solar photo voltaic can be used as a power source not just for satellites but as also the cleanest and greenest power source on earth. solar energy thus started being used not just for conventional purposes such as heating but also power generation [1]. modern pv cells are capable of converting up to 15% of the sun’s energy into dc electric power. sunlight provides roughly 100 watts per square foot to the earth’s surface, so on a clear day a 1square foot pv panel can produce about 15 watts. monocrystalline cell is also named single-crystal silicon cells and are the most common in the pv industry [1]. singlecrystal silicon has a uniform molecular structure compared to non-crystalline materials, its high uniformity results in higher energy conversion efficiency, more electricity is generated for a given area of exposure to the sunlight. the conversion efficiency for singlesilicon commercial modules ranges between 2030%. certainly, the performance of these cells depends on ambient parameters including: ambient temperature, wind speed, direct radiation, etc. [4]. mohammed e. abd al-wahed al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 7482 (2017) 75 in this work, there will be a study of the impact of these parameters on the performance of photovoltaic cells. 2. effects of environmental factors on photovoltaic cell in order to predict the energy production of photovoltaic cell, it is necessary to predict the cell temperature as a function of ambient temperature, wind speed, humidity and total irradiance. the cell temperature equation was determined by using minitab program. minitab has all the tools needed to effectively analyze the data. by guiding to the right analysis and giving clear results, minitab helps to create equation showing relationship between the cell temperature and all other factors by entering the experimental data in minitab program as below: tcell = 1.4 ta -0.566 w +13.97 h +0.01751 g 16.21 … (1) where: ta: ambient temperature w: wind speed h: humidity g: radiation the success rate of the equation was 96.22% “depending on experimental results” as shown in fig. 1, which refers to the relation between success rate of equation and all values of residual cell temperatures predicted by the program. all factors in this equation are predicted depending on the p-value in minitab program (ranging of p-value 0 to 0.05) and when the p-value approach to zero that’s mean the factor has a good effect in equation. the p-value of ambient temperature, wind speed, humidity, radiation and constant was 0.000, 0.01, 0.005, 0.000 and 0.002 respectively. fig. 1. residual plot for tcell. 3. modeling of photovoltaic solar cell using matlab/ simulink program mathematical model implemented in this work in order to study the effect of weather factors on power of pv module. also, it’s used for comparison between theoretical and experimental results. the main system of photovoltaic cell created as shown in fig.2. the blocks of photovoltaic cell are designed for simulation system according to the inputs and outputs of photovoltaic cell. the main system can change very quickly and easily. the main system of photovoltaic cell with obtained mathematical model of photovoltaic cell is established. the current of a pv module can be expressed, as function of voltage [2]. ip = isc . [ 1 – c1 . ( e ( v p / c 2 . v oc ) – 1) ] … (2) where c1 = ( 1 – impp / isc ) . e ( v mpp / c 2 . v oc ) … (3) c2 = [ (vmpp / voc ) 1] / ln [ 1 – ( impp / isc ) ] … (4) isc = short circuit current; voc= open circuit voltage; vmpp= maximum power point voltage; impp= maximum power point current; vp = voltage of pv module. such parameters can be expressed as follow: isc (g, t) = iscs . (g / gs ) . [1+α ( t – ts )] … (5) voc (t) = vocs + β ( t – ts ) …(6) impp (g, t) = impps . (g / gs ) . [1+α ( t – ts )] … (7) vmpp (t) = vmpps + β ( t – ts ) …(8) where parameters iscs, vocs, impps and vmpps are defined at standard conditions, stc (gs=1000w/m2 and ts=25°c) and α and β are respectively the current and the voltage temperature coefficient; all the above parameters are provided by manufacturers on module datasheet. it is possible to note that the parameters referred to currents depends on module solar irradiance g and temperature t, while the voltage ones depends only on temperature [2]. mohammed e. abd al-wahed al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 7482 (2017) 76 to improve the accuracy of the model it is convenient to modify expressions (6) and (8) by inserting a correction term, δv(g), taking into account voltage variation as function of solar irradiance: voc (g,t) = vocs + β ( t – ts ) ∆v (g) … (9) vmpp (g,t) = vmpps + β ( t – ts ) ∆v (g) … (10) correction term δv(g) is obtained by the following relationship: ∆v (g) = vocs vocm … (11) where voltage vocm represents the open circuit voltage of the iv curve translated from stc to the considered irradiance g and it defined as: vocm = c2 . vocs . ln [ 1 + [( 1it / iscs) / c1 ]] … (12) it is the short circuit current at irradiance g and can be written as: it (g) = iscs .(g/gs ) … (13) in order to determine the value of series rs, as function of panel parameters, it is convenient to express the module voltage as function of current by inverting eq. (2): vp = c2 . voc . ln [ 1 +[(1 – ip / isc ) /c1]] … (14) the value of series resistance rs can be calculated by deriving eq. (14) with the current calculated for ip=0: [2] rs = [d vp / d ip] ip= 0 = ( c2 . (voc / isc ) ) . (1/(1+c1 ) ) …(15) finally, we used the empirical equation that’s create by using minitab program as above mention (1) in order to find other parameters as shown in flow chart fig. 3. fig. 2. simulink model of weather factors effect on performance of pv solar cell. fig. 3. flow chart of mathematical model for pv solar cell. 4. experimental works the experimental work focused on the study the effect of weather factors on the performance of pv solar cell and modeling these results in matlabsimulink. these tests were conducted at the environment of baghdad city starting from nov. 2015 up to apr. 2016.the laboratory devices used through the experimental work was: • monocrystalline solar module with maximum power: 30w, cell area: 0.282m2, open circuit voltage: 22v, short circuit current: 1.9amp, voltage at maximum power: 17v, current at maximum power: 1.76amp. a standard calibration procedure has been made to the monocrystalline pv solar cells according to standard procedure supplied by the manufacture mohammed e. abd al-wahed al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 7482 (2017) 77 • prova 200 solar module analyzer used to measure output power, efficiency, fill factor (f.f), vmax, and imax of the solar module. • solar power meter “data logging solar power meter tes-1333r” simply measuring the radiation intensity in w/m². • temperature sensor used to measure the temperature of the pv solar cell. • weather station vantage pro2 used to measure the weather factors. 1. firstly, use a frame with angle 33.3˚, installing of monocrystalline pv solar cell, solar analyzer and thermometer towards the south. 2. using weather station vantage pro2 to measure weather factors such as ambient temperature, wind speed, humidity. 3. solar power meters placed at the surface of the pv solar cells vertically to measure the radiation flux 500, 750 and 1000w/m2. 4. connect solar analyzer prova 200 with the pv solar module electrodes to measure power and other electrical parameters such as voc, ish, vmax, imax, fill factor(f.f), and efficiency will be automatically calculated and then transferred the information to be store in work sheet of excel program. 5. measure the temperature of pv solar cells by temperature sensor. 6. measure the weather parameters such as ambient temperature, wind speed, cell temperature, radiation, and humidity in order to study their effects on voltage, current, power and efficiency of pv solar cell and modeling this results in matlabsimulink. 5. results and discussion 5.1 i-v and p-v characteristic for monocrystalline solar cell the influence of cell temperature on the i-v and p-v characteristic curve of monocrystalline solar cell has been evaluated under three different radiations intensity 500,750 and 1000 w/m².figures 4, 5 and 6 showing that the cell temperature has a strong influence on i-v and p-v characteristic of monocrystalline pv solar cell at constant radiation because its effect on open circuit voltage (voc). decreasing cell temperature, pv current decreases slightly while pv voltage increases clearly. output power of photovoltaic module increases with decreasing cell temperature up to 15°c. the maximum value of voltage (vmax) and open circuit voltage (voc) at radiation intensity, 500w/m² was 17.95 volt and 21.31 volt respectively on december at 19.1°c while they were equal to 16.5 volt and 20.06 volt on november at 38.2°c. also, the fill factor (f.f) changes directly proportional with the values of the vmax, imax. the best value of f.f achieved is 0.75, and the best value of efficiency was 12.3% in december. the maximum value of voltage (vmax) and open circuit voltage (voc) at radiation intensity, 750w/m² was 17.89 volt and 21.27 volt respectively on december at 23.1°c while they were equal to16.1 volt and 19.81 volt on november at 44.1°c. also, the f.f changes directly proportional with values of the vmax, imax. whereas the best value of f.f achieved is 0.75, and the best value of efficiency was 10.76% on march. also, noted these values of vmax and voc, and efficiency at radiation 750w/m² less than the values at radiation 500w/m² because the cell temperature was higher at radiation 750w/m². the maximum value of voltage (vmax) and open circuit voltage (voc) at radiation intensity 1000w/m², was 17.22 volt and 20.85 volt respectively on december at 30.3°c while they were equal to 15.58 volt and 19.63 volt on november at 48.1°c. also, the f.f changes directly proportional with values of the vmax, imax. whereas the best value of f.f achieved is 0.74, and the best value of efficiency was 10.25% on march. also, noted that values of vmax and voc, and efficiency at radiation 1000w/m² less than the values at radiations 500, 750w/m² because the cell temperature was higher than cell temperature at radiations 500, 750w/m². the short circuit current (isc) and maximum current (imax), increases with increasing radiation. these results matched with previously published data such as [4]. mohammed e. abd al-wahed al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 7482 (2017) 78 fig. 4. p-v and i-v characteristic of monocrystalline pv solar cell at constant radiation 500w/m². fig. 5. p-v and i-v characteristic of monocrystalline pv solar cell at constant radiation 750w/m². fig. 6. p-v and i-v characteristic of monocrystalline pv solar cell at constant radiation 1000w/m². mohammed e. abd al-wahed al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 7482 (2017) 79 5.2 effect of ambient temperature on power of monocrystalline pv solar cell the influence of ambient temperature on the power of monocrystalline solar cell has been evaluated under three different radiations 500,750 and 1000 w/m². figure 7 showing that the ambient temperature has a strong influence on power of pv solar cell, when the ambient temperature increases, the output power of the cell decrease due to increase cell temperature, therefore decreasing in voltage will occur, causing drop in the power of pv solar cell. this results matched with previously published data such as [5]. fig. 7. effect of ambient temperatures on power of monocrystalline pv solar cell at different radiation intensities. at radiation intensity 500w/m², the best value of power was 15.95, 16.9 watt experimentally and theoretically respectively when ambient temperature was 13.15°c in december. at radiation intensity 750w/m², the best value of power was 21.81, 26.76 watt experimentally and theoretically respectively where ambient temperature was 15.49°c in december. at radiation intensity 1000w/m², the best value of power was 28.82, 35.57 watt experimentally and theoretically respectively where ambient temperature was 20.73°c in january. 5.3 effect of wind speed on power of monocrystalline pv solar cell the influence of wind speed on the power of monocrystalline solar cell has been evaluated under three different radiations 500,750 and 1000 w/m². figure 8 showing that when the wind speed increase, the power of pv solar cell increase because of decreases the cell temperature due to increase wind speed. these results matched with previously published data such as [6]. at radiation intensity 500w/m², the best value of power was 15.95, 17 watt experimentally and theoretically respectively when the average wind speed was 0.73m/s in december. at radiation intensity 750w/m², the best value of power was 21.81, 24.74 watt experimentally and theoretically respectively when the average wind speed was 2.09 in december. at radiation intensity 1000w/m², the best value of power was 28.82, 32.67 watt experimentally and theoretically respectively when the average wind speed was 2.64m/s in january. mohammed e. abd al-wahed al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 7482 (2017) 80 fig. 8. effect of wind speed on power of monocrystalline pv solar cell at different radiation intensities. 5.4 effect of humidity on power of monocrystalline pv solar cell the influence of humidity on the power of monocrystalline solar cell has been evaluated under three different radiations 500,750 and 1000 w/m². figure 9 showing that when relative humidity decreased the output power of pv solar cell increases when the humidity decreases. this results matched with previously published data such as [7]. at radiation intensity 500w/m², the best value of power was 15.95, 16.79 watt experimentally and theoretically respectively where the average humidity was 21 in december. at radiation intensity 750w/m², the best value of power was 21.81, 24.97 watt experimentally and theoretically respectively where the average humidity was 27 in december. fig. 9. effect of humidity on power of monocrystalline pv solar cell at different radiation intensity. mohammed e. abd al-wahed al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 7482 (2017) 81 6. conclusions from the results obtained we can conclude the followings: • the cell temperature has a strong influence on performance of pv solar cells because its effect on open circuit voltage (voc). decreasing cell temperature, pv current decreases slightly while pv voltage increase clearly. output power of photovoltaic module increases with decreasing cell temperature. • the ambient temperature has a strong influence on performance of pv solar cells when the ambient increase, the cell temperature increase, therefore decreasing in voltage will occur, causing drop in the power of pv solar cell. • the wind speed has influence on performance of pv solar cells because its decreases the cell temperature, therefore increasing in voltage will occur causing increases in the power of pv solar cell. • low relative humidity increase in output current from solar panels. voltage output also increased with decrease in relative humidity. therefore the power of pv solar cell increases when humidity keeps at low values. • the decreasing of solar radiation has impact to the isc and voc. • were these differences between the experimental results and theoretical results are because of the inaccuracy of equipment and environment interactions, therefore noted that the theoretical power of pv solar cells more than actual and practical power. after calculated error ratio according to relation between experimental and theoretical results as show in below: • error (%) = (theoretical results – experimental results / experimental results) * 100 error ratio was equal 6.88, 5.91 and 4.53 when the radiation intensity equal 500, 750 and 1000 w/m² respectively. 7. references [1] r. siddiqui and u. bajpai, “statistical analysis of solar photovoltaic module output with temperature, humidity and wind velocity in composite climate,” european journal of scientific research, vol.80, no.4, pp.447–456, 2012. [2] bellini, a., bifaretti, s., lacovone, v. and cornaro, c. "simplified model of a photovoltaic module". international conference on applied electronics, pilsen, czech republic, 2009, 47-59. [3] shivan and apukhrem, "a photovoltaic panel model in matlab/simulink", renewable energy system, jun 28, 2015 [4] ike, c. u.: the effect of temperature on the performance of a photovoltaic solar system in eastern nigeria, international journal of engineering and science, vol.3, issue 12, 2013. [5] e. suresh kumar, bijan sarkar, “proportional hazards modeling of environmental impacts on reliability of photovoltaic modules". international journal of engineering and advanced technology (ijeat), volume-2, issue-2, 2012. [6] vijyant mahajan, “pv module and system fault analysis". thesis at murdoch university, perth, western australia, 2014. [7] r.ayaz, i.nakir, and m.tanrioven, “an improved matlab-simulink model of pv module considering ambient conditions". international journal of photo energy, volume 2014, issue 4, 2014. )2017( 74-82، صفحة 3د، العد13دجلة الخوارزمي الهندسية المجلم محمد عماد عبد الواحد 82 الجوية بنظراألعتبارالظروف أخذينالكريستالين ة احاديهالفوتوفولتائي ةخليال نمذجة بغداد مدينة في *فاضل عبد اللطيف ةاسام *محمد عماد عبد الواحد جامعة بغدادكلية الهندسة/ /قسم هندسة الطاقة* جامعة بغداد كلية الهندسة الخوارزمي/ /التصنيع المؤتمت هندسة قسم** mohammed.alwahed@yahoo.com :االلكتروني االلكتروني * drosamah65@gmail.com :البريد االلكتروني** الخالصة أجري هذا البحث تجريبيا . حيث الناتجه الطاقةو اللوح الشمسيعلى كل من كفاءة بشكل كبيرالظروف البيئية هي عوامل مهمة، ألنها تؤثر ودرجة من خالل رصد التغير في انتاج الطاقة من النظام مع الظروف البيئية مثل اإلشعاع الشمسي برنامج الماتالب في النتائج نمذجةتمت و ً ان هناك تناسب وجدنا النتائج خالل منو، وسرعة الرياح، والرطوبة في مدينة بغداد. لمحيطحرارة ا ً عكسي ا وأداء بين درجة حرارة المحيط ا أداء انتاج الطاقة من النظام.مع تناسبا طرديا تناسبفي حين أن سرعة الرياح ت والرطوبة وأداء انتاج الطاقة للنظام،انتاج الطاقة للنظام <4d6963726f736f667420576f7264202d20d3e3edd120e6dae1ed20edc7d3d1312d38> al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 14, no. 4, december, (2018) p.p. 18 experimental and finite elements analysis study of warming effect on deboned force for embedded nitinol wire into linear low density polyethylene samir ali amin* ali yasser hassan** *, **department of mechanical engineering/ university of technology *email: alrabiee2002@yahoo.com ** email: aliyasir1961@gmail.com (received 13 december 2017; accepted 7 march 2018) https://doi.org/10.22153/kej.2018.03.005 abstract this study presents the debonding propagation in single niti wire shape memory alloy into linear low-density polyethylene matrix composite the study of using the pull-out test. the aim of this study is to investigate the pull-out tests to check the interfacial strength of the polymer composite in two cases, with activation nitinol wire and without activation. in this study, shape memory alloy nitinol wire 2 mm diameter and linear fully annealed straight shape were used. the study involved experimental and finite element analysis and eventually comparison between them. this pullout test is considered a substantial test because its results have a relation with behavior of smart composite materials. the pull-out test was carried out by a universal tensile test machine type (laryee), load capacity (50 kn), and a test speed of 1mm/min. the finite elements modeling was performed by ansys v.15. the results of pull-out test showed that in the activation of nitinol wire embedded in host matrix linear low-density polyethylene (lldpe), the deboned force was about 74 n, but for the case without activation, it was about 106 n. deboned shear stress for the case with activation was about 0.73 mpa, but for the case of without activation, it was about 1.05 mpa. ansys result for deboned shear stress in case with activation was about 0.8 mpa. as for the case of without activation, deboned shear stress was about 0.99 mpa. the activation of the ratio of deboned shear stress and deboned force decreased by 30.47% and 30.13%, respectively. the error ratio between experimental and ansys results was equal to 8% for the case with activation and 5.7% for the case without activation. keywords: activation, composite material, finite element modeling, nitinol wire, pull-out test, shape memory alloy. 1. introduction composite materials are ordinarily employed in structures which require lightweight, yet strong components. there is still a need to enhance these materials, and there is a push to produce materials that have smart properties, which are able to sense, actuate and respond to the surrounding environment. the applications of smas in industry are many and variable, for example biomedical, space structures, automobile, vibration, shape control of wings for aero-structures and helicopters. smas are also applied in biomedical field, such as heart stents and orthodontics. martials without embedded shape memory alloys are nominal materials, but when smas are embedded in them, they become composite smart materials. it is an important test method commonly used to study the interfacial adhesion goodness, interfacial properties and elastic stress transfer between wires and matrix [1, 2]. the bonded forces between fiber and host matrix in composite materials play significant role. these forces, which are between the wire and host matrix, depend on the interfacial force. jonnalagadda et al. [3] studied the effect of different surfaces treatments of nitinol wires into samir ali amin al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 18 (2018) 2 host material to find the bond force utilize pull-out tests. several curing was inspected: untreated, acidetched, hand sanded, and sandblasted. the highest bond force was provided by sandblasting, while acid etching and hand sanding were less effective manners of improvement the bond force properties. n. a. smith et al. [4] studied the improvement of adhesion bond between the niti wire and silane coupling agents as the host matrix. black oxidecoated niti wire (0.03 inch diameter, nitinol devices and components, af 80℃) was excavated (20 min. sonication in conc. h2so4), degreased (hexanes, isopropyl alcohol and ultrapure h2o [millipore]; 20 min. sonication in each solvent), and exposed to a base/acid sequence to enhance the concentration of surface hydroxides (20 min. sonication in 1 m naoh, 5 min. sonication conc. h2so4). x-ray photoelectron spectroscopy was employed. the results indicated increasing of interfacial bonded roughly 100%. sadrnezhaad et al. [5] estimated the bond conduct between nitinol and a silicone matrix for medical applications. nitinol wires with various surface curing were examined by (sem), and pullout tests were led to determine the morph-logical and bonding interactions with the silicone host matrix. acid and oxidization increased the fricative forces at the interface which produced an increase in the bond force. xiaoling wang and gengkai hu [6] investigated the influence of temperature on the stress transfer during a pull out of a sma fiber from an elastic matrix. the results proved that the increase of temperature decreases the stress intensity factor. wambura mwiryenyi mwita [7] studied the effect of embedded nitinol wire (1 mm diameter) into polyurethane matrix in a silicon mold, prestrain technique was employed to stretch the wire by 3%. pull-out test and four-point bending test were performed. increasing in the flexural stiffness (ei) and fracture stress intensity factor (kic) of the composites plate was deduced. it was shown that the deboned force decreased when activating sma. payandeh et al. [9] investigated the effect of the transformation on the debonded inception in without pre-strained nitinol wire-epoxy matrix composites. nitinol wires were embedded in an epoxy coupon to achieve 6% and 12% nitinol wires volume fractions. epoxy coupons with nitinol wires volume fractions of 6% were tested in tension at 20℃, 80℃, and 90℃, whereas samples with nitinol wires volume fractions of 12% were examined at 80℃ and 90℃. increasing the nitinol wires volume fraction improved the mechanical conduct of the composite. mattia merlin et al. [9] investigated the effect of different surface treatments on the shape memory alloy nitinol wires into polyester (pe) and vinyl ester (ve) polymeric matrices. nitinol wire of diameter 0.5 mm was employed as fiber in this research. three types of recovery strain used, the first 4%, the second 5% and the third 6%. two types of chemical etching and a chemical bonding with a silane coupling agent were carried out on the surfaces of the wires. the results showed that the wires embedded in the pe resin indicated the maximum pull-out forces and the highest interfacial adhesion. eventually, it was found that the debonding induced by strain recovery is strongly related to the propagation towards the radial direction of sharp cracks at the debonding region. the aim of this research is to investigate pullout tests to check the interfacial strength of the polymer composite in two cases, with activation nitinol wire and with-out activation. 2. experimental work the experimental work is divided into two parts, the first part is manufacturing the injection mold for the composite model, and the second part is preparing the nitinol wire to injection. the testing is classified into two types, the first test is the pull-out test without activation nitinol wire, and the second test is the pull-out test with activation nitinol wire. 2.1 the used materials (i) the matrix (host): in this work, a linear low density polyethylene (lldpe) host material with a density about (0.920.93) gm/cm3 was used [10]. melting temperature of the host material is about 122.7⁰c, which was obtained by dsc test. plastic in form of grains was obtained from the sabic company in saudi arabia. (ii) the nitinol wire: in this research, a high temperature about 80°c±10°c nitinol wire, full annealed, (2 mm), with a straight shape and black color was employed, it consists of (ni-55%, h-0.001%, o0.05%, n-0.001%, c-0.05%, ti-balance), exported from nexmetal inc. 8780 19th alta loma, california 91701. the general properties of nitinol wire are shown in table (1): samir ali amin al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 18 (2018) 3 table 1, mechanical properties of nitinol wire [11] property value color black primary fiber direction (unidirectional) density (kg/m3) 6450 thermal expansion coefficient (10-6 k-1) 6.6-11 resistivity (µω cm) 80-100 thermal conductivity (w m-1 k-1) 10-18 melting temperature (k) 1573 heat capacity (j kg-1 k-1) 390 young modulus (austenite) (gpa)(test) 60000 young modulus (martensite) (gpa)tested 20000 austenite finish temperature(af) (k)tested 343 austenite start temperature(as)(k)tested 331 2.2 dsc test of polymer (lldpe) differential scanning calorimeter (dsc) is used to study the response of polymers to heating. dsc can be used to find the melting temperature or the glass transition temperature. the dsc set-up is composed of a measurement chamber and a computer. two pans are heated in the measurement chamber. a computer is used to monitor the temperature and regulate the rate at which the temperature of the pans changes. a typical heating rate is around 10 ℃/min. dsc test was done in university of baghdad, college of education for pure sciences ibn alhaitham central service laboratory. from this test, the melting temperature obtained was about 122.7℃ for polymer (lldpe), as shown in figure (1). fig. 1. dsc test diagram of melting temperature for (lldpe). 2.3 design and manufacture of an injection mold the injection mold was designed by auto cad program. the mold consists of three parts, upper, middle and lower part. the middle part called cavity part consisting of holes in every side was produced to pass the nitinol wire through them. the lower part was used to cool the sample model in cavity after the injection process. all parts are made from steel except the lower part is made from aluminum, to speed up the cooling process. the manufactured injection mold is shown in figure (2). fig. 2. the manufactured injection mold. 2.4 pull-out unidirectional nitinol wire without activation pull-out test was conducted in order to estimate the deboned load and maximum interfacial shear stress between the matrix (host material) lldpe and nitinol wires. the dimensions of the pull-out test specimen and pullout specimen are shown in figures (3) and (4), respectively. fig. 3. pull-out specimen with dimension in mm. lldpe block samir ali amin al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 18 (2018) 4 fig. 4. pull-out specimen the dimensions of the block are (l=40 mm, w=40 mm, and t=5 mm) and length of nitinol wire embedded in polymer block is le=40 mm [12]. a universal tensile test machine type (laryee), load capacity (50 kn), and a test speed of 1mm/min were used, the pull-out test is shown in figure (5). from the pull-out test, the relationship between applied load and nitinol wire displacement was plotted. fig. 5. pull-out specimen during testing by tensile universal machine. 2.5 pull-out unidirectional nitinol wire with activation the aim of this test is to investigate the effect of activation temperature of nitinol wire embedded in polymer matrix due to evaluated heat of polymer surface. another sample was used here with a same dimension, the nitinol wire was connected with a power supply and subjected to a current about 7.1a, and after specified time, the temperature of surface sample became 45℃. a universal tensile testing machine type (laryee), load capacity (50 kn), and test speed of 1mm/min as were used shown in figure (7). fig. 6. pull-out specimen during the activation. 3. fe modeling of pull-out test model the pull-out tests are classified into two tests, the first test was performed without activation of nitinol wire, and the second test was conducted with activation the nitinol wire. 3.1 fe modeling of pull-out test model without activation the model 3d pull-out test was created in ansys v.15. rectangular block has dimensions (l=40 mm, w=40 mm, t=5 mm), and nitinol wire has (lw=40 mm length). the nodal wire is connected with nodes for the rectangular after generation of nodes. the spring between the nodes embedded in the block gives the set of the functions between the effected force and displacement of wire. in this analysis, three types of elements were employed, the first element is 3d solid185 used for polymer host matrix a (lldpe), the second element is link180 used for nitinol wire with cross sectional area 3.14 mm2 and the third element is combin39 used to bond the nodes into the matrix. the pull-out model with meshing is shown in figure (8). this model applied the displacement on the tip of the end of the wire, and all the area of rectangular block is fixed. samir ali amin al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 18 (2018) 5 fig. 7. meshing of finite element 3d model of pullout test. 3.2 fe modeling of pull-out test model with activation the model of pull-out test applied in ansys codes is the same, but here some functions used in ansys codes must be given to explain the relationship between the deboned force and displacement of wire through the motion. the model meshing is the same in figure (8). the maximum interfacial stress was calculated according to the equation (1): [13] τimax = �� �∗� ∗ �� ... (1) where; τimax: deboned shear stress (mpa) fd: deboned force (n) le : nitinol wire embedded length (m) df: diameter of wire 4. results and discussion 4.1 results of experimental work the pull-out test was used to calculate the maximum deboned shear stress between nitinol wire and polymeric host material. shear stress can be calculated by considering the diagram between the deboned force and displacement using equation (1). the main purpose of using the nitinol wire in composite is to carry the load applied to composite, while the matrix holds and protects the wire, thus distributing the load between them [10]. this curve before activation nitinol wire is shown in figure (9). the second pull-out test included activation nitinol wire with suitable current by using dc power supply. the relationship between the deboned force and the displacement in activation case is shown in figure (10). fig. 8. pull-out test of nitinol wire without activation fig. 9. pull-out test of nitinol wire with activation 4.2 finite element modeling results from finite element analysis using ansys v. 15, one can get the contour of deboned shear stress without activation and with activation, as shown in figures (11) and (12), respectively. these results are in agreement with reference [7]. samir ali amin al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 18 (2018) 6 fig. 10. contour of deboned shear stress without activation wire. fig. 11. contour of deboned shear stress with activation wire. it clear now that in the activation nitinol wire embedded in host matrix (lldpe), the deboned force and shear stress are decreased, all the results are explained in table (2) below. through activation, the ratio of shear stress deboned and force deboned decreased by 30.47% and 30.13%, respectively. table 2, results of pull-out test in experimental and finite element modeling type of test experimental ansys error ratio deboned force (n) deboned shear stress (mpa) deboned shear stress (mpa) with activation 74 0.73 0.8 8% without activation 106 1.05 0.99 5.7% 5. conclusions in this research, the pull-out test in both cases was investigated, the first is with activation nitinol wire and the second is without activation nitinol wire. the following conclusions have drawn from this work: 1. in pull-out test, the activation decreases the deboned force. 2. activation of nitinol wire tends to decrease the deboned shear stress. 3. through activation, shear stress deboned and force deboned are decreased by 30.47% and 30.13%, respectively. 4. these results are beneficial for the design of smart composite materials. 5. a good agreement was found between the experimental and ansys results with a maximum percentage of error 8% with activation and 5.7% without activation. notation lldpe linear low density polyethylene sam shape memory alloy sme shape memory effect sem scanning electron microscopy dc direct current pe polyester ve vinyl ester acknowledgements the authors gratefully acknowledged materials engineering department in university of technology for providing the needed devices for experiments and for the support this work. 6. references [1] zhou, l.-m., kim, j.-k., mai and y.-w., interfacial debonding and fiber pull-out stresses. part ii a new model based on the fracture mechanics approach, j. mater. sci., 27 (1992) 3155-3166. [2] zhou, l.-m., mai, y.-w. and baillie, c., interfacial debonding and fiber pull-out stresses. part v a methodology for evaluation of interfacial properties, j. mater. sci., 29 (1994) 5541-5550. [3] jonnalagadda k, kline g and sottos n. local displacements and load transfer in shape memory alloy composites. exp. mech 1997; 37(1):78-86. samir ali amin al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 18 (2018) 7 [4] n.a. smitha, g. g. antounb, a. b. ellisa, and w.c. cronec. “improved adhesion between nickel–titanium shape memory alloy and a polymer matrix via silane coupling agents”, composites: part a 35 (2004) 1307–1312. [5] sadrnezhaad s, nemati n and bagheri r. improved adhesion of niti wire to silicone matrix for smart composite medical applications. mater design 2009; 30(9):366772. [6] xiaoling wang and gengkai hu,” stress transfer for a sma fiber pulled out from an elastic matrix and related bridging effect”, composites: part a 36 (2005) 1142–1151. [7] wambura mwiryenyi wita,“development and testing an intelligent hybrid polymeric composite beam with healing ability embedded with nitinol shape memory alloy embedded with ni-ti shape memory alloy“, msc thesis, cape peninsula university of technology , faculty of engineering, department of mechanical engineering, december (2010). [8] payandeh y, meraghni f, patoor e, and eberhardt a. study of the martensitic transformation in niti-epoxy smart composite and its effect on the overall behavior. mater design 2012; 39:104-10. [9] mattia merlin, martina scoponi, chiara soffritti, annalisa fortini, raffaella rizzoni and gian luca garagnani.,” on the improved adhesion of niti wires embedded in polyester and vinylester resins”, m. merlin et alii, fracture ed integrate structural, 31 (2015) 127-137; doi: 10.3221/igf-esis.31.10. [10] c. s. cai, wenjie wu, suren chen, and george voyiadjis,” applications of smart materials in structural engineering”, department of civil engineering, louisiana state university, state project no. 736-991055, october 2003. [11] f. calkins, j. mabe, r. and ruggeri,” overview of boeing’s shape memory alloy based morphing aerostructures”, proceedings of smasis08: asme conference on smart materials, adaptive structures and intelligent systems, october 28–30, 2008, ellicott city, md (2008). [12] ali sadiq yasser,” the effect of fiber pretension on the static and dynamic behavior of composite plates”, phd thesis, machines and equipment engineering departments, university of technology, (2001). [13] william f. smith and javad hashmi, handbook, “foundations of materials science and engendering “, fourth edition (2006). 1088 pages, mcgraw-hill education. )2018( 18، صفحة 4، العدد14دجلة الخوارزمي الهندسية المجلمعلي امين سمير 8 العناصر المحددة لتاثير التسخين على قوة االنسالخ لسلك النيتينول دراسة عملية وتحليل مغمور داخل بولي اثيلين خطي منخفض الكثافة * علي ياسر حسن**امين عليسمير قسم الهندسة الميكانيكية/ الجامعة التكنولوجية*،** alrabiee2002@yahoo.com :البريد االلكتروني * aliyasir1961@gmail.com:البريد االلكتروني ** الخالصة باستخدام هذا البحث يقدم دراسة نشوء االنسالخ لسلك نيتينول مفرد سبيكة ذاكرة الشكل داخل بولي اثيلين خطي منخفض الكثافة مصفوفة مركبة دراسة هذا البحث دراسة فحص السحب لتحقق من قوة التداخل لمركب بوليميري في حالتين، مع تنشيط سلك النيتينول وبدون تنشيط . في فحص السحب. الهدف من مليمتر شكل مستقيم كامل التصليب قد استخدم. الدراسة شملت العملي وتحليل العناصر المحددة واخيرا ٢هذا البحث سيكة ذاكرة الشكل سلك نيتينول قطر ً فحص السحب فحص دنة بينهم. يعالمقار ً اساسي ا آلة اختبار الشد العالميبسبب نتائجه لها عالقة بسلوك المواد المركبة الذكية. فحص السحب قد نفذه بواسطة ا . نتائج فحص ١٥ر طة انسيز االصدااسوملم/دقيقة قد استخدمت. نفذت نمذجة العناصرالمحدد ب ١كيلو نيوتن، سرعة الفحص ٥٠نوع (الري) ، ذو سعة حمل نيوتن، لكن في حالة بدون ٧٤السحب اثبتت عند تنشيط سلك النيتينول المغمورداخل مصفوفة المضيف بولي اثيلين خطي منخفض الكثافة، قوة االنسالخ حوالي ميكا باسكال. خالل التنشيط النسبة ٠٫٩٩ميكا باسكال، لكن بدون تنشيط حوالي ٠٫٧٣نيوتن. اجهاد قص االنسالخ في التنشيط حوالي ١٠٦تنشيط حوالي في حالة بدون %٥٫٧في حالة التنشيط و %٨على التوالي. نسبة الخطأ بين النتائج العملية واالنسزز ، %٣٠٫١٣و %٣٠٫٤٧الجهاد قص االنسالخ تقل بي تنشيط. ملخص البحث 6222 / 2لعدد / ا 2 مجلة الخوارزمي الهندسية ,المجلد / د.عدنان نعمة عبود 1 بطريقة اللحام النقطي بالقوس din 15mo3لحام الفوالذ منخفض السبك المعدني المحمي بالغاز عامر عبد اهلل طعمة د.نبيل كاظم عبد الصاحب د.عدنان نعمة عبود المعدات الهندسية الثقيلة كلية الهندسة الخوارزمي بغداد -الكلية التقنية هيئة التعليم التقني جامعة بغداد وزارة الصناعة )6200 4 april2005; accepted 14 november(received -:ملخص البحث ام النقطااي بااالقوس المعاادني المحمااي بالغاااز تناااول البحااث دراسااة تاايرير متغيااراي اللحااام حااي طريقااة اللحاا (mig/mag spot) الكاااربون لبيااان ماادر تيرير مااا حااي الخااواص درو كساايغاااز رالركااون وراااني باساتخدام وتحديااد الظاارو (din15mo3)الميكانيكيااة والبنيااة المة ريااة لوصاالة لحااام الفااوالذ الماانخفض الساابك نااو رساتخدمقاو القاص. رظ اري النتاامك نمكانياة اختبارام رعتمادا" على المرلى لعملية اللحام من تيار وزمن اللح ال غااز االركاون حاي لحاام الفاوالذ المانخفض السابك ما رنخفااض محادود حاي قاو القاص بدال" عن 2coغاز 2coغاز رالركون بدال" مان استخدامقو القص عند ازدادي. (2sec)وزمن (4mm)لسمك (%31) ريتعد وبتياااااار (8sec)وزمااااان (2mm)عناااااد رساااااتخدام غااااااز رالركاااااون ولسااااامك (36kn) قاااااو القاااااصلتصاااااب (220amp.) 2رما عند رستخدام غازco بدال" من رالركون حينخفضي قو القص الى(31kn) حيث بلغاي رماا (37.9kn)كاناي (.290amp)وتياار (8sec)ولازمن (4mm)( بينماا لسامك 13نسبة رالنخفاض )% (30.9kn)بلغي ح 2coعند رستخدام غاز حكانااي قااو القاااص (.450amp)وتيااار (8sec)ولاازمن (6mm)( ولساامك 1.81ري بنساابة رنخفاااض )% (39kn) 2رسااتخدام غاااز وعناادco بلغااي(37kn) %( 18.5ري بنساابة رنخفاااض. ) "ركاادي النتااامك ريضااا تناسبا" طرديا" م زياد تيار اللحام وزمنه. هونفاذيتتناسب قطر اللحام انب النظريالة.1 حي حالة لحام الفوالذ المنخفض السابك ترتفا والمنطقااة المتاايرر (wm)صااةد منطقااة اللحااام م مااا كااان معاادل التبريااد بطيمااا" (haz)بااالحرار عاليااة علااى كااون ااذا النااو ماان الفااوالذ ذو قابليااة عناصر السابك حياه. ويمكان معرحاة التصليد لتواةد علاااى حسااااب المكااااحي اللحاااام باالعتمااااد قابلياااة للفاااااوالذ (carbon equivalent) الكااااااربوني .(1)المنخفض السبك al-khwarizmi engineerin journal al-khwarizmi engineering journal, vol.2,no.2,pp 1-19 (2006) 6222 / 2لعدد / ا 2 مجلة الخوارزمي الهندسية ,المجلد / د.عدنان نعمة عبود 2 ce=c+mn/6+(cr+mo+v)/5+(ni+c u)/15…....(1) يعطي ناتك ذه المعادلة انطباعاا" عان قابلياة قيمة المكاحي كانيالتصليد وقابلية اللحام, وكلما الكااااربوني عالياااة كاناااي قابلياااة التصاااليد عالياااة نذ (martensite)يحتماال تكااون طااور المارتنسااايي لاذلك تكاون (haz)حي المنطقة المتايرر باالحرار وكلمااا كاناي قيمااة المكاااحي قابلياة اللحااام واطماة. ( كاني قابلية لحام الفاوالذ 0.4الكاربوني اقل من ) نذا رماا. مسابقةتحضايراي نلاى الحاةةةيده بدون حااان قابليااة (0.7 0.4)كانااي قيمااة المكاااحى التساااخين نلاااى رلحاةاااه اللحاااام تكاااون اقااال وتظ ااار كاني نذا رما. o(100(cو 400)c)oالمسبق بين ( حتكااون 0.7ماان ) ركراارقيمااة المكاااحى الكاااربوني .(4-1) واطمهقابلية اللحام باااااالقوس mig/magبطريقاااااة اللحاااااام رن يساااتخدم للحاااام المعاااادن ذواي الك رباااامي القصاااير وكااذلك األحقاايل وحااي موضاا اللحااام الساامك القلياا خلااايط رو( ar) رو co)2يمكااان اساااتخدام غااااز ) اساااااااااااااااااااتخدام رن نذ 2co-.(arالغاااااااااااااااااااازاي ) 75%ar)-2(25%co يعطااي اسااتقرارا" للقاااوس الك ربااامي ومظ اارا" ةياادا" لخااط اللحااام ويقلاال ماان مسااتور تنااارر المعااادن ويعطااي خااواص ميكانيكياااه الخلااايط .وبشاااكل عاااام حاااان اساااتخدام اااذا مقبولاااة النتاااامك مااا تقنياااة اللحاااام باااالقوس رحضاااليعطاااي 5)-(27رالقصي رلرشااي" اللحااام بااالقوس الك ربااامي ريضااايمكاان وان 2co-(arو) 2o-(arماا خلاايط الغااازاي ) حاي اللحاام األحقايتستخدم حي الوضا رلتقنيه ذه اللحام بعاد تمرياراي للمعاادن ذاي روبتمرير واحد مساااااتور تيااااااراي اللحاااااام السااااامك العاااااالي. وعناااااد رساتخدم .العمودي يمكن اللحام بالوض المنخفضة mn-mo-cb-steel , v-n-steelالفاوالذ بطريقة لحام النقطة حي صناعة السياراي بدال" من الن ل اذه sae1008الفوالذ المانخفض الكااربون . الماااذكور الطريقااة مواصااافاي تفياااد حاااي الصاااناعة باسااتخدام نفااس حةاام رةريااي عمليااة لحااام النقطااي سااالك اللحاااام وقاااو الضاااغط وزمااان اللحاااام ولااانفس ححاص متاناة الشاد علي اا. تباين ان ورةرا السمك مستور التيار المطلوب حي لحام الفاوالذ المانخفض يكاااون اقااال (hsla) العالياااةالسااابك ذو المتاناااة ماان مسااتواه حااي الفااوالذ الماانخفض الكاااربوني. ورن -mn ذ للفااوال رلنقطااهقابليااة لحااام mo-cb-steel تكاااااون مشااااااب ه للفاااااوالذv-nsteel وسااااةل اللحااااام انخفاضااااا" حااااي مسااااتور , hslaحاااااااي الفاااااااوالذ (ductility) رلمطيلياااااااه -sae ,ما الفاوالذ المانخفض الكااربون بالمقارناة وانخفااض حاي رلمطيليهوارتفا محدود حي 1008 ما بالمقارناة (nugget)صاةد منطقاة اللحاام .v-n-steel ان كاااااة مااااانmn-mo-cb-steel بالمقارنااةلحااام ةيااد يعطااى قابليااة v-n-steelو من التيار روس يعطيان مدر نذ sae1008م (4)متساويةومتانة شد رعلىوقو قص يمكااااااان hslaحاااااااان معااااااادن وبالنتيةاااااااة اسااتخدامه حااي ةمياا متطلباااي صااناعة السااياراي حي ةمي االختبااراي. تام ةالمطلوبلتحقيقه النتامك الحصاااول علاااى عةقاااة ةياااده باااين متاناااة القاااص ومساحة منطقة اللحاام وكاذلك متاناة الشاد لمنطقاة .(4)اللحام ومساحة منطقة اللحام for mn-mo-cb-steel: σcts=-28100 d2+27900 d-1270………(2) for v-n-steel: σcts=-30000 d2+28100 d-1900………………(3) for sae 1008: σcts=-5000 d2+14600 d-120……………..…(4) where σcts= tension strength (psi) d= diameter (inches) الةانب العملي.. 6222 / 2لعدد / ا 2 مجلة الخوارزمي الهندسية ,المجلد / د.عدنان نعمة عبود 3 تاااااام رةاااااارا عمليااااااة اللحااااااام بطريقااااااة لحااااااام (mig/mag spot) لصاااافام مختلفااااة حااااي ماان الفااوالذ 6mm , 4mm , 2mmساامك ال نااااااااااااااااو (2,1)ةدول الماااااااااااااااانخفض الساااااااااااااااابك (din15mo3) لحام متغير من تياار حي ظرو متنوعاة و اي حماياةغازاي وباستخداموزمن لحام غاز رااني روكسايد الكااربون وغااز رالركاون. لتقيايم لوصاااةي اااذه الملحومااااي تااام ححاااص قاااو القاااص لتحدياد رحضال الشاد اختباارة ااز باستخداماللحام الظرو لمتغيراي عملية اللحام. اللحااااام المصاااان حسااااب ساااالك رسااااتخدمتاااام باالرمز (aws)مواصفة ةمعياة اللحاام االمريكياه er80s-g والتركيااااااااب الكيمياااااااااوي والخااااااااواص ( 4,3نااو مبينااة حااي الةااداول )لالميكانيكيااة ل ااذه ر رناااه ححاااص بموةاااب المواصااافة نلاااى رإلشاااار مااا section ii part casme .(28) رألمريكية او غااز األولناوعين مان الغاازاي رستخدمتم (12l/min)راني روكسيد الكاربون بمعدل ةريان الخاملاااةوالرااااني غااااز االركاااون و اااو مااان الغاااازاي تااام تحضاااير (4l/min).وبمعاادل ةرياااان راباااي العينااي لعمليااة اللحاام وحسااب المواصافة القياسااية (aws) ( ي5والةاادول ) وضاا العةقااة بااين ربعاااد (29)العينة وسمك المعدن المراد لحامه. رنةزي عملية اللحام بعد تحضير العيناي وت يمة المسبق لظرو اللحام اإلعدادالماكنه عن طريق وزاوية (1.2mm)كسلك اللحام المستخدم بقطر . تم (dcrp)وقطبية اللحام o(90(ررس القطب " من حدوث ابتدا ام مختلفة اللحام بتياراي لح (failure)مرحلة الفشل نلىاللحام وصوال" خمس عيناي لكل ظر . نلىبمعدل رةث رن شكل منطقة اللحام يكون دامري التخاذه شكل حو ااة اللحااام المصاانوعة ماان النحاااس التااي تحاااحظ -510)على حرار القوس داخل ا وبمادر تياار مان ( رانيه..,4,.رمبير والزمان لحام ) (190 din15mo3 ( التركيب الكيمياوي للفوالذ رلسبامكي1ا لةدول ) 6222 / 2لعدد / ا 2 مجلة الخوارزمي الهندسية ,المجلد / د.عدنان نعمة عبود 4 din15mo3 ( الخواص الميكانيكية للفوالذ رلسبامكي.الةدول ) er80s-g( التركيب الكيمياوي للسلك 3الةدول ) er80s-g( الخواص الميكانيكية للسلك 4الةدول ) ( العةقة ما بين ربعاد العينة وسمك المعدن1الةدول) تم اختبار قو القص لوصةي اللحام بة از الشد material yield strength mpa tensile strength mpa elongation % hardnass hb nominal mechanical properties 265 440-570 23 130-170 din15mo3 274 510 25 153 element c% si% mn% mo% nominal chemical composition 0.07-0.12 0.50-.080 1.60-2.10 0.40-0.60 er80s-g 0.5. 0.51 1.93 0.54 material c% mn% cr% ni% mo% cu% v% co% nominal chemical composition 0.1-0.35 0.4-0.9 <0.35 <0.3 0.2-0.3 / / <0.3 din15mo3 0.15 0.58 0.24 0.23 0.26 0.11 0.012 0.012 material yield strength mpa tensile strength mpa elongation % nominal mechanical properties 460 530-670 22 er80s-g 468 610 25 thickness of thinner sheet (t) (mm) specimen width(w) (mm) recommended length(l) (mm) up to 0.73 16 76 0.76-1.5 25.4 102 1.5-2.9 38 127 3-4.8 50.8 152.5 5 and over 76 203 6222 / 2لعدد / ا 2 مجلة الخوارزمي الهندسية ,المجلد / د.عدنان نعمة عبود 5 نيكيااة الم مااة ورالكراار الااذي يعااد ماان االختباااراي الميكا يمكاان بااه معرحااة رقصااى نذشاايوعا" حااي اللحااام النقطااي اليمكن االعتماد على ححص نذقو قص لوصلة اللحام مقاوماة الشاد لعادم انتظاام مسااحة نقطاة اللحاام للتغيار ظارو اللحاام. ويساتخدم اخاتة الذي يطرر علي ا م ليااة ااذا االختبااار غالبااا" لتحديااد الظاارو المراليااة لعم اللحاااام والتاااي تساااةل عناااد رعلاااى قاااو قاااص لوصاااةي اللحام. متغيراي تيرير النتامك والمناقشة.3 اللحام على خواص الملحوماياللحام 2coبغاز الحماية نو aws er80s-gسلك اللحام اختيارتم اختياربموةب متطلباي المواصفة التي يعتمد يكية السلك على ما تحققه من مواصفاي ميكان حضة" عن األساسممارلة رو رعلى من المعدن تواحق التركيب الكيمياوي. حاااي الداخلاااةيعاااد التياااار رحاااد ر ااام المتغياااراي حااي رلمااررره mig/mag spot عمليااة اللحااام قااو القااص لوصاالة اللحااام ألن زياااد تيااار اللحااام منطقااة نلاى الداخلاة الحارار زيااد كمياة نلاىتاردي بااين قااو العةقااة( 3,2,1) األشااكال اللحااام. تمراال القص وتيار اللحام الزمان مختلفة. يتبين من األشكال المذكور رن قو القص التيار ورن ذه الزياد حي قو ازديادتزداد م مدر معين من التيار رم تبدر نلىالقص تكون باالنخفاض لتكون قة اللحام وحدوث تنارر حي الشقوق حي منط نقصان نلىالتي يردي (splashing) عدن الم السمك حي منطقة اللحام وحدوث الفشل. عنااد تيااار ( رن اللحااام يباادر1يةحااظ ماان الشااكل ) علاى (2mm). حبالنسبة للسامكيقابله زمن معين (190amp)يباادر اللحااام عنااد تيااارساابيل المرااال وتياااااااار 8sec)و ) (4sec)بااااااازمن لحاااااااام 210amp)عنااد زماان لحااام ) .(2sec) ري رن التيااار ياانخفض ماا زياااد زماان ماارور التيااار. وقااد رعلى قو قص (8sec) و (4sec)سةل الزمن (27.5kn)( بقيماة (240amp ار اااااد تيااااعن سةلي رعلى قو قاص و على التوالي. (31kn)و بلغااي نذ (240amp)عنااد تيااار (2sec)لاازمن رااام تصاااارحي المتغياااراي بااااذاي (22kn).قيمت اااا غة ماان حيااث رنخفاااض قااو القااص بعااد زياااد الصااي زماان اللحااام وتياااره عاان القاايم المرشاار . رن زياااد سااااعد علاااى (8sec) نلاااى (4sec)الااازمن مااان ( رماا .118)% نلاىزياد قو القاص بنسابة تصال ( حقااد راحقت ااا زياااد 8sec) عاانزياااد زماان التيااار رن الاازمن نلااىحااي نساابة تنااارر المعاادن ممااا يشااير (8secوتياا ) 240ار amp) يعطيااان رعلااى قااو ) .2mmقص للسمك 160 200 240 280 320 weld current (amp) 10 15 20 25 30 35 s h e a r f o r c e ( k n ) 8sec 4sec 2sec ( العةقه بين تيار اللحام وقو اللحام لسمك 1الشكل ) 2mm 2بيستخدام غازco وبيزمان مختلفه ( حي تياراي ورزمان 2بد اللحام )الشكل مقارنة بالسمك (4mm)لسمك مختلفة .(2mm) ( 14)بلغي قيمة قو القصkn عند ( رم تبدر قيمة 4secوزمن ) (.260amp)ر تيا قو القص بالزياده م رزدياد التيار وصوال" الى ( عند تيار30.9knقيمت ا العظمى ) (290amp) وزمن (8sec) ومن رم الى .(amp 360)مرحلة الفشل عند تيار 6222 / 2لعدد / ا 2 مجلة الخوارزمي الهندسية ,المجلد / د.عدنان نعمة عبود 6 240 270 300 330 360 390 weld current (amp) 10 15 20 25 30 35 s h e a r f o r c e ( k n ) 8sec 4sec 2sec بيستخدام 4mm ( العةقه بين تيار اللحام وقو اللحام لسمك 2الشكل ) بيزمان مختلفهو 2coغاز ( حيبدر اللحام 3) الشكلالمنحنياي حي رما مختلفةمن تياراي ورزمان (6mm)ولسمك رن قيمة قو القص تبدر من ريضا". (16.4kn)( 390)عند تيار amp وزمن (4sec) "رم تبدر قيمة قو القص بالزياده وصوال 450)عند تيار ) (37kn)الى قيمت ا العظمى amp وزمن(8sec) ومن رم الى مرحلة الفشل .amp 600)عند تيار ) 350 400 450 500 550 600 weld current (amp) 8 16 24 32 40 s h e a r f o r c e ( k n ) 8sec 4sec 2sec 6mm ( العةقه بين تيار اللحام ومتانة اللحام لسمك 3الشكل ) وبيزمان مختلفه 2coبيستخدام غاز تيرير زمن اللحام .4 يعتبر زمن مرور تيار اللحام رحد المتغيراي mig/mag spotالم مة حي عملية اللحام بين المتولد الحرار ب تيريره حي كمية وذلك بسب القطعتين المراد لحام ما. تزداد قو القص م زمن مرور تيار اللحام والى مدر معين رم زياد تبدر باالنخفاض بسبب مرور التيار ولفتراي زمنية الحرار حي كمية الزياد نلىطويلة مما يردي ام ومن رم تنارر المعدن من منطقة اللح المتولد والذي ينتك منه نقصان حي سمك وصلة اللحام. بمعدل ةريان 2coحعند رستخدام غاز (12l/min) نةحظ رن بداية اللحام ولسمك (2mm) ( 2وعند زمنsec) تكون عند تيار (210amp) وبقو قص ضعيفه نسبيا ((12.2kn (. بينما تكون بداية 4-1)شكل ار عند تي (8sec) و(4sec) اللحام الزمان (190amp) ( 13.7) وبقو قصkn و ((14.9kn على التوالي. كما نةحظ من الشكل عند زمن (4mm)( رن بداية اللحام لسمك 4-.) (2sec تكون عند تيار )(270 amp) وبقو بينما تكون بداية 13kn)قص ضعيفه تبلغ ) عند تيار (8sec)و (4sec)اللحام الزمان (260 amp) ( 14وبقو قصkn و ) (18.4kn على التوالي. بينما كاني بداية ) ( وتيار2secعند زمن ) (6mm)اللحام لسمك amp)4.1( وبقو قص )9.5kn والزمان ) (4sec) و(8sec) عند تيار(390amp) على (20kn)و (16.4kn)وبقو قص (. من ذلك يتض ضرور 3-4التوالي )شكل رير ما الموازنه مابين تيار اللحام وزمن اللحام لتي الكبير حي قيمة قو القص لوصلة اللحام . رلصفيحهتيرير سمك .1 6222 / 2لعدد / ا 2 مجلة الخوارزمي الهندسية ,المجلد / د.عدنان نعمة عبود 7 يعتبر سمك المعدن المراد لحامه من mig/mag spotالمحدداي حي عملية اللحام حعند زياد سمك وصلة اللحام نحتاج الى تياراي وازمان عاليه ألةرا عملية اللحام وبالتالي زياد ( .( )1يةحظ من االشكال )قطر منطقة اللحام. التباين الواض حي قيمة التيار م رختة ( 3) السمك. رن زياد سمك وصلة اللحام تاردي الاى زيااد قيمة التيار والزمن المطلاوب لتولياد الحاراره الكاحياه يحتااج (6mm)الةرا عملية اللحاام ورن السامك لتحقياااق لحاااام النقطاااه (450amp)الاااى حاااوالي ى قو قاص ممكناه لاذلك حاان زيااد السامك بيقص سااااايتعارض مااااا مااااادياي مكاااااامن لحاااااام (mig/mag spot) والتااااي ااااي غالبااااا" ال .( (amp 600تتةاوز الحمايةغاز .6 الم مةرحد المتغيراي الحمايةيعتبر غاز الميكانيكيةالتي تررر حي نوعية اللحام والخواص القوس الك ربامي من خةل تيريره حي رستقرارية وبالتالي حي نفاذية اللحام وعلى قطر نقطة اللحام ( 3,2,1)لإلشكالوعلى قو القص . حبالرةو حي الحمايةنةحظ تيرير غاز ( 6,5,4)ورالشكال قو القص . ( بمعدل 2co (حعند رستخدام غاز بلغي رقصى قو قص لسمك (12l/min)ةريان (2mm) 22 يkn) ( عند زمن )2sec) ( عند (31knو (sec4( عند )27.5knو) (. وعند رستخدام غاز االركون بمعدل (8sec زمن ولنفس السمك كاني قو (4l/min)ةريان (2secعند زمن ) (25kn)القص العظمى ي kn 36)و) (4sec( عند زمن )(kn 31.7و ( رر بزياد تتراوح ما بين 8secعند زمن ) االركون. رما ( لصال غاز 11(الى )%.1)% حسةلي عند رستخدام (4mm)العيناي سمك غاز االركون زياد حي قو القص وبيزمان مختلفه (.3.%-1وبنسبة تراوحي مابين )% ( حين 6mmوعند لحام عيناي سمك ) ساعد حي co)2( بدال" من ) (arرستخدام غاز زياد قو القص بنسبة محدوده رعتمادا" على حيزدادي قو القص العظمى الزمن المستخدم ( .1و )% (2sec)( عند زمن 14بنسبة )% (8sec)( عند زمن 1و )% (4sec)عند زمن يعزر ذا االختة حي قو القص العظمى الى التركيز العالي للقوس الك ربامي لةركون. تبين قيمة (3)و (2)و (1)والةداول (2mm)رالنخفاض حي قو القص ولةسماك و (2sec)والزمان (6mm)و (4mm)و (4sec) و(8sec) . 180 200 220 240 260 280 weld current (amp) 10 20 30 40 s h e a r f o r c e ( k n ) 8sec 4sec 2sec وبيستخدام 2mm ( العةقه بين تيار اللحام وقو اللحام لسمك 4الشكل ) وبيزمان مختلفه arغاز 6222 / 2لعدد / ا 2 مجلة الخوارزمي الهندسية ,المجلد / د.عدنان نعمة عبود 8 180 220 260 300 340 380 weld current (kn) 0 10 20 30 40 s h e a r f o r c e ( k n ) 8sec 4sec 2sec وبيستخدام 4mm ( العةقه بين تيار اللحام وقو اللحام لسمك 5الشكل ) وبيزمان مختلفه arغار 350 400 450 500 550 600 weld current (amp) 10 20 30 40 s h e a r f o r c e ( k n ) 8sec 4sec 2sec وبيستخدام 6mm تيار اللحام وقو اللحام لسمك ( العةقه بين6الشكل ) وبيزمان مختلفه arغار تيرير متغيراي اللحام حي قطر نقطة .7 اللحام راني روكسيد الكاربون غاز187 حي قطر الم مةيعتبر التيار رحد المررراي ( 12,11,10,9,8,7) األشكالنقطة اللحام. من حي الحمايةوغاز نةحظ تيرير التيار وزمن اللحام حعند لحام عيناي بسمك قطر منطقة اللحام. (2mm) وبتيار قدره(210 amp) وبيستخدام ( بلغ 2sec( وعند زمن )4-7شكل ) 2coغاز . وعند زياد التيار (3.6mm)قطر منطقة اللحام (4.7mm)يزداد قطر نقطة اللحام وصوال" الى . ومن (8sec)وزمن (amp 220)عند تيار كد رن سبب الزياد حي قطر منطقة اللحام المر ناتك من زياد كمية الحراره الداخله الى وصلة اما عند لحام عيناي ذاي سمك اللحام . (4mm) بتيار(270 amp) وبيستخدام غاز 2co ( وبزمن 4-.شكل )(2sec) بلغ قطر ورزداد القطر م زياد (5.7mm)نقطة اللحام عند تيار (7.4mm) التيار والزمن وصوال" الى (290 amp) وزمن(8sec) وعند لحام . 425)بتيارقدره (6mm)عيناي ذواي سمك amp) وبنفس الزمن بلغ قطر منطقة اللحام (6.9mm) ورزداد الى(11mm) لحام)عند تيا (450amp. وزمن(8sec) . كذلك حين زمن اللحام له تيرير م م حي قطر نقطة اللحام حعند وزمن لحام (2mm)اي سمك لحام عيناي ذو (2sec وتيار )(210amp) وبيستخدام غاز 2co كاني قطر منطقة اللحام(3.6mm) وعند وعند زمن (3.9mm)( كان sec4زمن ) (8sec كان )4.3mm) يةحظ ازدياد قطر .) نقطة اللحام بزياد الزمن ريضا" ويعزر ذلك الى زياد زمن مرور تيار اللحام الى القطعه المراد لحام ا مما يسم بوةود حتر كاحيه لةنص ار الةيد وبالتالي زياده حي قطر نقطة اللحام . 4mm)وعند لحام عيناي ذواي سمك ) ولنفس الظرو السابقه من زمن وغاز الحمايه عند تيار ) mm187حين قطر نقطة اللحام يكون ) (270 amp.) وعند زمن(4sec) بلغ القطر (6mm) وعند زمن(8sec) رزداد القطر ليبلغ (6.5mm) . ولنفس ظرو (6mm)رما عيناي ذواي سمك ( حقد بلغ 4-1اللحام من زمن وغاز حمايه شكل ) ( عند تيار mm)681قطر نقطة اللحام بحدود (425 amp) وعند زمن(4sec) بلغ القطر 6222 / 2لعدد / ا 2 مجلة الخوارزمي الهندسية ,المجلد / د.عدنان نعمة عبود 9 (7.6mm) وعند زمن(8sec) رزداد القطر . (11mm)ليبلغ 180 200 220 240 260 weld current (amp) 0 2 4 6 8 s p o t d i a m e t e r ( m m ) 8sec 4sec 2sec م رستخدام 2mmير التيار حي قطر نقطة اللحام لسمك ( تير7الشكل ) والزمان مختلفه 2coغاز 240 280 320 360 weld current (amp) 0 2 4 6 8 s p o t d i a m e t e r ( m m ) 8sec 4sec 2sec م رستخدام 4mm( تيرير التيار حي قطر نقطة اللحام لسمك .) الشكل والزمان مختلفه co2غاز 360 400 440 480 520 560 weld current (amp) 0 4 8 12 s p o t d i a m e t e r ( m m ) 8sec 4sec 2sec ما رساتخدام mm 6( تيرير التيار حي قطر نقطة اللحاام لسامك 1)الشكل والزمان مختلفه 2coغاز arغاز .1 قطر نقطة تررر غازاي الحمايه ريضا" حي بين غازي الحماية االشكال اللحام حالمقارنه ( تبين رنخفاض .1( )11( )15( )1( ).( )7) قطر نقطة اللحام عند رستخدام غاز االركون ( ولنفس ظرو اللحام 2coمقارنة بيستخدام ) من تيار وزمن لحام نتيةة" لتمركز القوس .الك ربامي الخاص باالركون ( 2mmحعند لحام عيناي ذواي سمك ) amp 210)( وعند تيار )2secوزمن لحام ) ( يكون قطر 4-7( شكل )2coوبيستخدام غاز) اما عند رستخدام غاز ) mm) 386نقطة اللحام ((ar (ولنفس ظرو اللحام حيكون 4-15شكل ) عيناي . وعند لحام (2.8mm)قطر نقطة اللحام ( عند 2sec( وزمن لحام ) (4mmذواي سمك ( 2coوبيستخدام غاز ) (290amp)تيار (.mm) 68( يكون قطر نقطة اللحام4-.شكل) لنفس ظرو اللحام arاما عند رستخدام غاز ( حيكون قطر نقطة اللحام 4-11شكل) .(5.8mm) ونةحظ العيناي سمك(6mm) رن ا تسلك نفس السلوك من خةل تيرر ا بغاز الحماية. 160 180 200 220 240 260 weld current (amp) 0 2 4 6 8 s p o t d i a m e t e r ( m m ) 8sec 4sec 2sec م رستخدام 2mm( تيرير التيار حي قطر نقطة اللحام لسمك 15الشكل ) والزمان مختلفه arغاز 6222 / 2لعدد / ا 2 مجلة الخوارزمي الهندسية ,المجلد / د.عدنان نعمة عبود 10 180 210 240 270 300 330 360 weld current (amp) 0 2 4 6 8 s p o t d i a m e t e r ( m m ) 8sec 4sec 2sec م رستخدام 4mm( تيرير التيار حي قطر نقطة اللحام لسمك 11الشكل ) والزمان مختلفه arغاز 360 400 440 480 520 560 weld current (amp) 0 4 8 12 s p o t d i a m e t e r ( m m ) 8sec 4sec 2sec mmقطر نقطة اللحام لسمك حيير التيار ( تير.1الشكل ) والزمان مختلفه arم رستخدام غاز 6 تيرير متغيراي اللحام حي النفاذية.. رستخدام غاز راني روكسيد الكاربون ..18 المررراي حي نفاذية ر ميعتبر التيار رحد نةحظ ( 14,13) األشكالاللحام . حبمةحظة حي نفاذية الحمايةاز تيرير التيار وزمن اللحام وغ (4mm)حعند لحام عيناي ذواي سمك اللحام. ( 2sec( ولزمن ) (270ampبتيار قدره كاني نفاذية اللحام 2coوباستخدام غاز (4.9mm وعند زياد تيار اللحام تزداد النفاذيه ) عند تيار (7.8mm)وصوال" الى رحضل نفاذيه (360 amp) وزمن(8sec) بعد ا يسبب . اط حي كمية الحراره الداخله تنارر حي المعدن االحر (splashing) من ذلك نستنتك رن الزياده حي نفاذية اللحام بزياد الزمن يعزر الى زياد زمن مرور تيار اللحام الى منطقة اللحام مما يسم بوةود حتره كاحيه لةنص ار الةيد وبالتالى زياد .النفاذيه رالركون غاز استخدام..8. يةحاظ حمايةغاز االركون كغاز رستخدمعند 2coما غااز حبالمقارناةتيريره حي نفاذياة اللحاام غااااااز رساااااتخدمنةحاااااظ رنخفااااااض النفاذياااااه عناااااد حعنااد لحااام عيناااي ذواي ( 14,13شااكللا )االركااون وزمان لحاام (amp 250)بتياار (4mm)سمك (sec4 )2(غااااااز وباسااااتخدام(co حاااااين عماااااق ( ولانفس ظارو اللحاام mm181النفاذيه يكاون ) حااين ar)غاااز ) وباسااتخدامماان زماان وتيااار لحااام وعماق النفاذياه (4.7mm) عمق النفاذياه يكاون وتياار co)2غاز ) وباستخدام( 8secعند زمن ) يقابل ااااا 5.7mm)( يكااااون )250ampلحااااام ) . بلااااااغ ar (4.9mm))غاااااااز ) اسااااااتخدامعنااااااد رالخاااتة حاااي النفاذياااة باااين الغاااازين عناااد سااامك (4mm) ( وزماان لحااامsec4 ولاانفس ظاارو ) ( ولانفس السامك ما زمان 1481اللحام بحادود )% (8secكاني النسب )%( 14ة) 240 280 320 360 weld current (amp) 4 5 6 7 8 p e n e t r a t i o n ( m m ) 8sec 4sec 2sec 6222 / 2لعدد / ا 2 مجلة الخوارزمي الهندسية ,المجلد / د.عدنان نعمة عبود 11 ورستخدام 4mm( العةقه بين تيار اللحام والنفاذيه لسمك 13الشكل ) 2coغاز 160 200 240 280 320 360 weld current (amp) 2 4 6 8 p e n e t r a t i o n ( m m ) 8sec 4sec 2sec ورستخدام غاز 4mm( العةقه بين تيار اللحام والنفاذيه لسمك 14الشكل ) ar microhardnessالصةده الدقيقه.1 ررري متغيراي اللحام بشكل ملحوظ حي ةود للحرار نتيةة" رلمة ريه البنيةاللحام وعلى ( يوض 15حي ررنا اللحام. والشكل ) المتولد ولزمن لحام (340amp)لتيار الصةد قيمة (sec4 )2 ازغ باستخدام.co الصةد تم قياس لوصةي اللحام من مركز نقطة اللحام رلدقيقه حيث لوحظ ارتفا األساسالمعدن نلىوصوال (345hv)اللحام حي مركز الصةد قيمة انخفاض اواستقرار ا على طول نقطة اللحام رم بالحرار المتيرر المنطقة نلىتدريةيا عند الوصول . 153hv)) ساألساالمعدن نلىوصوال حي مركز الصةد ارتفا رن السبب حي اللحام و صغر الحةم الحبيباي حي منطقة اللحام (wm) منطقة وزياد حةم ا حي(haz) ايي حي ز وكذلك تكون المارتن األساسوالمعدن منطقة اللحام . 320لتيار الصةد ( قيمة 16يوض الشكل ) amp)( ولزمن لحام )sec4 )غاز ستخداموبا ar حي مركز للصةد حيث تكون رعلى قيمه 380)على طول نقطة اللحام واستقرار االلحام hv) رم تبدر باالنخفاض تدريةيا حي المنطقة للصةد لتعطي رقل قيمه (haz) بالحرار المتيرر ((153 hv قيمة اختة .من ذا نةحظ رن مك لنفس الس الحمايةغاز اختة م الصةد معدل التبريد لمنطقة اللحام اختة يعود الى التي تررر بشكل كبير الداخلة الحرار وحسب كمية حي الحةم الحبيبي لمنطقة اللحام والمنطقة . بالحرار المتيرر 0 2 4 6 distance from weld center (mm) 150 200 250 300 350 400 m i c r o h a r d n e s s ( h v ) wm haz bm بيستخدام غاز 4mm( يمرل منحني الصةده الدقيقه لسمك 15الشكل ) 2co رانيه 4وعند زمن 0 2 4 6 distance from weld center (mm) 150 200 250 300 350 400 m i c r o h a r d n e s s ( h v ) wm haz bm بيستخدام غاز 4mmمنحني الصةده الدقيقه لسمك ( يمرل 16الشكل ) ar رانيه 4وعند زمن الفحاااااااااااااااااااااااااااااااص المة اااااااااااااااااااااااااااااااري .15 microstructure 6222 / 2لعدد / ا 2 مجلة الخوارزمي الهندسية ,المجلد / د.عدنان نعمة عبود 12 رلمة اااري( صاااور التركياااب 17يمرااال الشاااكل ) قبل رةارا din15mo3الدقيق للمعدن األساس عملية اللحام التي تشمل علاى ررضاية مان الفراياي (50µm)بااي وتةمعااي ماان البرالياي وبحةاام حبي ( لطور البراليي.58.46للفرايي وبكسر حةمي ) ( صور التركيب رلمة ري الدقيق للمعدن األساس 17الشكل ) din15mo3 (wm)( معدن اللحام .1يوض الشكل ) (240amp)عند تيار (2mm)لعينه سمك حمايةغاز وباستخدام (2sec)ولزمن 2co, يبية كمناطق سودا ه الحدود الحبتظ ر حيو (22µm)ايي حي ا وبحةم حبيبي ز لتةم المارتن (. 58361وبكسر حةمي بلغ ) ( صااااور لمعاااادن اللحااااام 11ويبااااين الشااااكل ) (wm) ولساااااااااااامك (2mm) وعنااااااااااااد وباساااتخدام( sec) 4ولاازمن (240amp)تيااار ريضا" وتكون حي اا الحبيبااي رنعام مان 2co غاز ابق لزيااااد زمااان مااارور تياااار تلاااك حاااي الااازمن السااا وكسااار حةماااي (18µm)اللحاااام وبحةااام حبيباااي ( تايرير زيااد 5.ض الشكل )(. بينما يو 58441) زماااان ماااارور تيااااار اللحااااام حااااي حةاااام الحبيباااااي و (4sec)بالمقارناااااة مااااا رالزماااااان (2sec)حيااث يعتباار الاازمن(8sec) ااو الاازمن ي المرااالي لعمليااة اللحااام والااذي ينااتك عنااه حبيبااا والكسر (15µm)ناعمة حيث بلغ الحةم الحبيبي وبالتالي يظ ر تايريره للمارتنزايي (5845) رلحةمي الااى رصاااحةالواضا حااي قاايم الصااةد وقااو القااص زيااد كميااة المارتنزايااي المتكاون وتوزيعااه المنااتظم على طول منطقاة اللحاام مقارناة بيالزماان رالخارر. 2coز رن زياااااد الاااازمن بوةااااود تيااااار ماااا غااااا ساعدي على سرعة التبريد م رعطا بناى ناعماة من الفرايي والمارتنزايي. __ بين االنتقالية( صور المرحلة 1.يمرل الشكل ) والمنطقة المتيرر (wm)منطقة اللحام ر و ذكمولنفس وصلة اللحام ال (haz)بالحرار رنفا" . حيث يةحظ التباين حي حةم الحبيباي بين ferrite pearlite (+fe) m200 m200 co.2غاز (8sec)ولزمن (2mm)لعينه سمك (wm)( معدن اللحام 5.الشكل ) m200 ferrite martensite 6222 / 2لعدد / ا 2 مجلة الخوارزمي الهندسية ,المجلد / د.عدنان نعمة عبود 13 و المنطقة المتيرر بالحرار (wm)منطقة اللحام (haz) رن حبيباي منطقة اللحام تكون ناعمة . ويظ ر تكون المارتنزايي حي ا بينما تكون حبيباي المنطقة المتيرر بالحرار كبير " نسبيا" م رنخفاض ( لطور المارتنزايي 5837) حةميرلالكسر 2coالختة معدل التبريد. وعند رستبدال غاز (2mm)بغاز االركون ولنفس السمك يةحظ رن (8sec)ولزمن (240amp)وتيار ( تكون رصغر حةما" ..منطقة اللحام )شكل وكسر حةمي بلغ (13.9µm) وبحةم حبيبي حي قيمة الصةد وقو ارتفا ( م 58.1) يوحر اللحام بغاز االركون منطقة خالية من القص. . 2h(24)العيوب السيما العيوب الناتةة من غاز ( يةحظ رن 5.( م الشكل )..وبمقارنة الشكل ) كمية المارتنزايي بوةود االركون رقل و ذا يرة العزل الحراري الذي يوحره االركون مقارنة ب نلى 2co ركد مما يعطي معدالي تبريد رقل. ومن الم رن االرتفا حي الخواص الذي راحق غاز االركون يرة الى خلو منطقة اللحام من العيوب السيما .2hوةود غاز ferrite——— martensite (8sec)ولزمن (2mm) لعينه سمك (wm)( معدن اللحام 5.الشكل ) co.2وغاز wm haz m200 m200 (2sec)ولزمن (2mm) لعينه سمك (wm)( معدن اللحام .1الشكل ) co.2وغاز وغاز (4sec)نلزم (2mm)لعينه سمك (wm)( معدن اللحام 11الشكل ) 2co ferrite martensite (haz)والمنطقة المتيرر بالحرار (wm)( منطقة اللحام 1.الشكل ) 2coوغاز (8sec)ولزمن (2mm)لعينه سمك m200 m200 6222 / 2لعدد / ا 2 مجلة الخوارزمي الهندسية ,المجلد / د.عدنان نعمة عبود 14 m200 ferrite ————— (2mm)لسمك معدن اللحام ( 4-22الشكل ) ar خدام غازوبيست (8sec)ولزمن ( يمراااال صااااور لمعاااادن اللحااااام 23الشااااكل ) (wm) بسمك(4mm) وعند تيار(340amp) ,حيااث يةحااظ رن 2co وغاااز (4sec)ولاازمن زياد السمك يراحق ا زيااد حاي قيماة التياار والازمن المطلااوب الةاارا عمليااة اللحااام وبالتااالي الحصااول حاااي منطقاااة (31µm)علاااى حبيبااااي كبيااار الحةااام (. 58471ام وبكسر حةمي يبلغ )اللح co.2وغاز (4sec)ولزمن (4mm)( لسمك 23الشكل ) ( صاور لمعادن اللحاام 24يتض من الشكل ) (wm) غاز باستخدامar ولانفس ظارو اللحاام وتياااااااااااار (4mm)الساااااااااااابقة مااااااااااان سااااااااااامك (340amp) وزمااان(4sec) ألساااتخدم. رن ه الواضا حاي تايرير 2coبادال" مان غااز االركاون ( حيااااااث ..583للمارتنزايااااااي ) رلحةماااااايالكساااااار عاةو علاى 2coرنخفض بشكل واض مقارناة ب رن العزل الحراري ساعد ريضا" على زياد الحةم martensite اد الحبيبي للفرايي م ذلك سةلي ذه العيناي زيا .حي قو القص والصةد ferrite ————— martensite (4mm)ولسمك (wm)( صور لمعدن اللحام 4-42الشكل ) (ar) وبيستخدام غاز (4sec)ولزمن و كذا حين زياد السمك سيراحق ا زياد حي مقدار تيار اللحام وزمن مروره مما يررر حي زياد كمية الحرار الداخلة. ظ ري حي البنية المة رية لمعدن (550amp)وعند تيار (6mm)ك لسم تةمعاي من (8sec)وزمن (wm)اللحام المارتنزايي بشكل ركرر وضوحا" م زياد حي ( 58317ليبلغ ) رلحةميكسر ا (wm)( صااور لمعاادن اللحااام 1.يبااين الشااكل ) وعناااااااد (6mm)لسااااااامك arغااااااااز باساااااااتخدام ردي زيااااد (8sec)ولااازمن (550amp)تياااار arبادال" مان غااز 2coغااز مرستخدالسمك م للمارتنزايااي بحاادود رلحةماايالكساار انخفاااض نلااى ( ماا مةحظااة رن التساارب الحااراري الااذي .5833) راحق زياد السمك قد قلل من تايرير العازل الحاراري العالي لغااز االركاون . رن اذا التاداخل ربقاى علاى m200 m200 6222 / 2لعدد / ا 2 مجلة الخوارزمي الهندسية ,المجلد / د.عدنان نعمة عبود 15 خاااواص ملحومااااي االركاااون رعلاااى مااا التيكياااد رن تفاعال احتمالية" رضاحية السيما مضارا 2coلغاز للاااان تحااااالذري الناتك ع ناااألوكسةي 2co co+o م عناصار السابك وتكاون رة از نلاىاالكاسيد التي مما الشك يحتااج رربات اا scanning)الماساا ححااص كة اااز المة اار microscope). (8sec)ولزمن (6mm)ولسمك (wm)( لمعدن اللحام 1.)الشكل arغاز وباستخدام conclusionsاالستنتاةاي .11 نمكانيااة لحااام صاافام الفااوالذ الماانخفض .1 باساااااتخدام din15mo3السااااابك ناااااو (mig/mag spot)طريقاااااااة وباسااااتخدام er80s-gوبساااالك لحااااام .غاز االركون يمكاااان لحااااام الفااااوالذ الماااانخفض الساااابك .. 15mo3 2بغاااازco غااااز حضاااة" عااان االركااااون ماااا رنخفاااااض حااااي قيمااااة قااااو لسااااامك .1القاااااص ساااااةلي بمقااااادار % 2mm 250عند تيارamp).) يمكن لحام وصةي من الفوالذ المنخفض .3 رعتماااادا" علاااى السااامك 15mo3السااابك بماادر ماان التيااار وزماان اللحااام لتحقيااق نلاى اإلشاار ما المطلوباةمقاومة القص رن زياد التياار والازمن عان مقادار معاين يقابل ااا حاادوث رنخفاااض حااي قااو القااص يتبع اااااا الفشااااال بسااااابب تناااااارر المعااااادن المنص ر حي منطقة اللحام. الزياااد حااي قطاار وصاالة اللحااام ونفاذيت ااا .4 تتناساااب طردياااا مااا زيااااد تياااار وزمااان اللحام . غاااااز االركااااون حااااي عمليااااة رسااااتخدمرن .1 اللحام يعطي قو قص رعلاى مماا يعطي اا قيمة تيار لنفس السمك وعند 2coغاز .2coرقل مما حي حالة غاز غااااز رساااتخدمقطااار منطقاااة اللحاااام عناااد .6 غاااز رسااتخدماالركااون رقاال ممااا ااو عنااد 2co وذلاااك لتمركاااز القاااوس الك رباااامي الخاص باالركون. ظ ااااور طااااور المارتنزايااااي الساااايما حااااي .7 حااااي منطقااااة اللحاااااام (6,4,2) رألسااااماك والمنطقاااة المتااايرر باااالحرار ساااوا ا" عناااد رو االركاااون لتصااال 2coغااااز رساااتخدم ( كساار حةمااي للمارتنزايااي 58471) نلااى وتياااااااااااااااار ((4mmعناااااااااااااااد سااااااااااااااامك (340amp.) وزمن(4sec) . سااااةلي الملحوماااااي التااااي نفااااذي بغاااااز .. كساار حةمااي للمارتنزايااي 2coالحمايااة ركباار مقارنااة بغاااز الحمايااة االركااون عنااد لطبيعاااة األخاااررتربياااي ةميااا المتغياااراي المراحااااق لغاااااز ىاألعلااااالعاااازل الحااااراري سةلي منطقة اللحاام كسار بينما االركون حةمااااي لطااااور المارتنزايااااي رعلااااى ماااان المنطقة المتيرر لكة الغازين مماا يرشار التاايرير المباشاار لغاااز الحمايااة حااي زياااد معدالي التبريد حي منطقة اللحام. سةلي منطقاة اللحاام رعلاى قايم للصاةد .1 رر المة رياااااة مقارناااااة بالمنطقاااااة المتاااااي بااالحرار نظاارا" لظ ااور المارتنزايااي بكساار ( (hazحةماااي رعلاااى مقارناااة بمنطقاااة m200 6222 / 2لعدد / ا 2 مجلة الخوارزمي الهندسية ,المجلد / د.عدنان نعمة عبود 16 حااي منطقااة (hv341وبلغااي الصااةد ) وتيااااااااااااار (4mm)اللحااااااااااااام لساااااااااااامك (340amp.) وزماااااان(4sec) مقارنااااااة . 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aluminum alloy to steel with transition material from process to performance part1: experimental study” welding journal ,vol.83 , no.5 , 2004 , pp.188-s – 195-s. 26. s.zhang "approximate stress formulas for amultiaxal spot weld" welding journal , vol.80 , no.10 , 2001, pp 145 177. 27. j.senkara "cracking in spot welding aluminum alloy" welding journal , vol.79 , no.7, july 2000 , pp. 191-s – 202-s. 28. asme "material specificationsection-ii –part-c welding rods, electrodes and filler metals" 1998. 29. iiw , ”specimen dimension and procedure for shear testing resistance spot and projection welds” welding in the word, annual subscription vol.18 , no.1/2 , 1980 , pp.41 – 44. 6222 / 2لعدد / ا 2 مجلة الخوارزمي الهندسية ,المجلد / د.عدنان نعمة عبود 19 welding of low alloy steel din 15mo3 by mig/mag spot abstract: this research deals with the effects of welding variables using mig/mag spot by using l characteristics and mechanicato show their effect on the 2 gas and co (ar) argon microstructure of low alloy steel type din15mo3 and determine the optimum condition 2the results show the possibility of using co. for the process of welding ; current & time and also ar in low alloy steel welding with a little decrease in the shear force of not more the shear force increased when using ar .for 4mm thickness and time 2sec %3than 1 the shear force reach 36kn when using ar at 2mm thickness time to be , 2instead of co ead of ar decreased shear force to inst 2of 8 sec and current of 220 amp. , when used co 31kn reach decrease rate 13% while for a thikness of 4mm , time 8sec and acurrent of became 30.9kn decrease rate 18.5% and for a 2 when used co, kn.9290amp. it was 37 it become 2as 39 kn when used cothikness of 6mm , time 8 sec and 450amp. current it w 37kn redusing rate 5.20% .the diameter and penetration of welding have straight relation with the increase of current and time. سعد زغلول al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 8, no. 1, p.p. 19-28 (2013) tuning pid controller by neural network for robot manipulator trajectory tracking saad zaghlul saeed al-khayyt department of mechatronics engineering/ college of engineering/ mosul university email: alkhyaat@yahoo.com (received 7 may 2012; accepted 18 february 2013) abstract ziegler and nichols proposed the well-known ziegler-nichols method to tune the coefficients of pid controller. this tuning method is simple and gives fixed values for the coefficients which make pid controller have weak adaptabilities for the model parameters variation and changing in operating conditions. in order to achieve adaptive controller, the neural network (nn) self-tuning pid control is proposed in this paper which combines conventional pid controller and neural network learning capabilities. the proportional, integral and derivative (kp, ki, kd) gains are self tuned on-line by the nn output which is obtained due to the error value on the desired output of the system under control. the conventional pid controller in the robot manipulator is replaced by nn self tuning pid controller so as to achieve trajectory tracking with minimum steady-state error and improving the dynamic behavior (overshoot). the simulation results showed that the proposed controller has strong self-adaptability over the conventional pid controller. keywords: pid controller, neural network, self tuning controller, robot manipulator, trajectory tracking. 1. introduction robotics has become recently an interesting area of research, especially the robot manipulator control. industrial robot manipulators of high accuracy require complicated methods of control. a robot manipulator is a nonlinear system with high coupling terms whose dynamics consists of uncertainty and is encountered with payload changes, friction and disturbance [1]. applying a control technique is important to guarantee high efficiency and lower error for the motion of the robot. research of modern control theory is prompted recently and many methods have been proposed for the design of controllers. pid controller is considered the most control technique that is widely used in control applications. it provides robust and reliable performance for most systems if the coefficients are tuned properly [2]. among the existing tuning techniques, the zieglernichols formula may be the most well-known method. but tuning is laborious and timeconsuming, particularly for processes with serious nonlinearities. therefore, this method usually needs retuning before being used to control industrial process [3]. however pid controllers cannot provide a general solution to all control problems when the processes are complex and time-variant, with delays and non-linearity, often with poorly defined dynamics and measurement noise [4]. therefore, an operator is still needed to have control over the plant. to enhance the capabilities of traditional pid tuning techniques, several methods such as embedding the lyapunov stability criterion [5], the neural networks [6-12], the fuzzy logic controllers [13-15], and the genetic algorithm (ga) [16,17] have been developed recently to tune the parameters of pid controllers. in these previous works, it was shown that better control performance can be achieved in comparison with the ziegler-nichols method. however if pid controller parameters are tuned off-line, these controllers will not maintain the desired control performance and stability during operation [18]. thus on-line tuning is proposed in the works of [7,9,12] using multilayered neural network with mailto:alkhyaat@yahoo.com saad zaghlul saeed al-khwarizmi engineering journal, vol. 9, no. 1, p.p. 19-28 (2013) 20 model reference and also occasionally with estimator. also for pid gains tuning of nonlinear multivariable systems, gas offers a solution in combination with multilayered several neural networks for each design criterion in addition to the iterations involved in the algorithm [17]. neural network (nn) has a strong selfadaptability, learning ability, and nonlinear mapping capability. to work on-line is actually a challenging task for strongly nonlinear systems and frequently considered important than off-line. in on-line procedure, data is simultaneously used to get current output and to optimize the parameters at the same time [19]. in order to achieve good control performance, the nn self tuning pid controller method is proposed. this method combines conventional pid controller and single layer nn. the nn tunes the kp, ki, and kd gains of the pid controller in on-line procedure. by doing so, we overcame the tuning limitation of pid controller using classical tuning methods. 2. neural network pid self tuning for undetermined system’s model, experimental methods such as ziegler-nichols tuning rules may be used to design pid controller. let the transfer function of a pid controller be written as )τs τs 11(kp)( d i ++=sgc …(1) where kp, τi , τd are the proportional gain, the integral time, and the derivative time, respectively [20]. initially the derivative and integral terms are set to zero. the proportional gain is increased from zero to a critical gain value (kcr) where the system exhibits sustained oscillations. using the value of critical gain (kcr) and the period of oscillation (pcr), the value of parameters kp, τi, τd are determined according to the formulas given in table 1. table 1, ziegler-nichols tuning rules based on critical gain and period of oscillation [20]. controller kp τi τd p 0.5 kcr ∞ 0 pi 0.45 kcr 1/12 pcr 0 pid 0.6 kcr 0.5 pcr 0.125 pcr generally for robot arm, the only way to build a high-performance control system is to make use of feedback from joint sensors. typically, this feedback is used to compute any servo error by finding the difference between the desired and the actual position and that between the desired and the actual velocity. this paper proposes two inputs – single output self tuning of a pid controller as shown in fig.1. the controller design uses the desired trajectory and the error as inputs to self tuning, and the nn output (y(t)) as output. the error signal (e) is defined as the difference between the desired position (θr) and actual position (θ) of joint angle for robot arm. the nn output is added to the conventional pid controller to adjust the gains of the pid controller on-line according to the change of the error signal. this ensures that the nn will provide the required change in the control signal (u) on-line. now the control action of the pid controller after using the nn output (y(t)) can be described as: dt e(t)dkdteke(t)ku dnninnpnn ∫ ++= …(2) where kpnn, kinn, and kdnn are the new gains of pid self tuning controller and equal to: kpnn = y(t) · kp, kinn = y(t) · ki, kdnn = y(t) · kd. fig. 1. proposed neural network self-tuning pid controller. 3. adaptive linear network the adaline has been and one of the most widely used neural networks found in practical applications. however, as single-layer linear networks are just as capable as multilayer linear networks. a linear neuron uses linear transfer function termed purelin which simply returning the value passed to it. the adaline network shown in fig.2 below has one layer of s neurons connected to r inputs through a matrix of weights w [21]. the output is obtained as: saad zaghlul saeed al-khwarizmi engineering journal, vol. 9, no. 1, p.p. 19-28 (2013) 21 a = purelin (w · p + b) = w · p +b …(3) where a = network output vector of s rows, w = weight matrix of s rows and p columns, b = bias vector of s rows. this neuron can be trained to learn an affine function of its inputs, or to find a linear approximation to a nonlinear function. the least mean square error algorithm adjusts the weights and biases of the adaline so as to minimize this mean square error. fig. 2. the adaline network architecture. adaptive filtering is one of its major application areas. a tapped delay line can be combined with an adaline network to create the adaptive filter. this adaptive filter is used to predict the next value of a stationary random process, p(t). we use the network shown below to do this (fig.3). the network changes the weights on each time step so as to minimize the error e(t). if this error is zero, then the network output a(t) is exactly equal to p(t), and the network did its prediction properly. fig. 3. adaptive filter based on adaline network [21]. in the proposed controller, the error signal (e(t)) is defined as the difference between the desired position (θr) and actual position (θ) of joint angle for robot arm. the network, once initialized and operating, adapts at each time step on-line to minimize the error and in a relatively short time is able to predict the required output (y(t)). saad zaghlul saeed al-khwarizmi engineering journal, vol. 9, no. 1, p.p. 19-28 (2013) 22 4. manipulator’s dynamic equations the complete algorithm for computing joint torques from the motion of the joints is composed of two parts. first, link velocities and accelerations are iteratively computed from link 1 out to link n and the newton−euler equations are applied to each link. second, forces and torques of interaction and joint actuator torques are computed recursively from link n back to link 1. the dynamic equation, which is a function of joints angle position (θ), can be written in the form [22]: ( ) ( ) ( ) )θf(θgθθ,v θθm &&&& +++=τ …(4) where m(θ) is the n x n mass matrix of the manipulator, ( )θθ,v & is an n x 1 vector of centrifugal and coriolis terms, g(θ) is an n x 1 vector of gravity terms, f(θ& ) is an n x 1 vector of friction, and τ is an n x 1 vector of joints torque. for two-link planar manipulator (fig.4), the above matrices become: ( )                   + + +++ = 2 2l2m )2cos(θ2l1l2m2 2l2m )2cos(θ2l1l2m 2 2l2m )2cos(θ2l1l22m 2 2l2m2 1l )2m1(m θm               −− = 2 1θ )2 sin(θ2l1l2m 2θ1θ )2sin(θ2l1l22m )2 sin(θ2 2θ2l1l2m )θv(θ( & && & &               + + ++ = )2θ1cos(θ2lg2m )2θ1cos(θ2lg2m )1cos(θ1l)g2m1(m g(q)         = 2θkμ0 01θkμ)θf( & & & where m1 & m2 = mass of link one and two respectively, l1 & l2 = length of link one and two respectively, μk = coefficient of kinetic friction. fig. 4. two-link planar manipulator with point masses at distal ends links. 5. simulation and results simulation results are obtained so as to test the proposed nn self tuning pid controller. we compared the results of pid classical tuning method and nn self tuning method in terms of overshoot, transient response, and steady state error. the tracking path from the initial position to the final position is considered in this paper. a tapped delay of 4 is used for all simulations. all simulations were presented using matlab and simulink, which are used widely in control applications. the time step used in simulation is 0.001 second. at first, the response of step desired joint angle position input is tested for single-link robot manipulator [23]. the dynamic equation is given as τ=++ )(sin102 θ td θd td θd 2 2 …(5) large overshoot, settling time, and steady state error are obtained for conventional pid controller as shown in fig.5. pid gains are: kp=45, ki=65 and kd= 4. the proposed nn self tuning improves the response through reducing the settling time, overshoot, and steady state error. the output of the nn is increased so as to reduce the error as shown in fig.6. pid gains are: kp=45 and kd= 4. the transient mean square error (mse) and root mean square (rms) error are reduced from (0.03138) and (0.14349) to (0.00978) and (0.09887), respectively. the results of comparison are presented in table 2. saad zaghlul saeed al-khwarizmi engineering journal, vol. 9, no. 1, p.p. 19-28 (2013) 23 0 1 2 3 4 50 0.2 0.4 0.6 0.8 1 1.2 1.4 time, s po si tio n, ra d pid controller proposed controller fig. 5. response for step input of conventional pid and proposed nn self tuning of pid. 0 1 2 3 4 5 0 20 40 60 80 100 120 time, s y( t) fig. 6. variation of nn output (y(t)) for desired step input. table 2, results of comparison for single-link robot manipulator. controller delay time (sec.) rise time (sec.) maximum overshoot % settling time (sec.) mse (rad) rms (rad) pid 0.1810 0.31 28.8 1.500 0.03138 0.14349 proposed nn self tuning pid 0.0657 0.267 0.00978 0.09887 then two-link robot arm is considered to follow a circular trajectory (figs 7-10). the robot links’ parameters are presented in table 3. when the controller is pd only as in [24], the system has bad tracking. therefore pid controller is used and the proportional gain (kp) is increased to ten times. the pid gains are: kp = [310 0; 0 450], ki=[400 0; 0 635], and kd = [60 0; 0 80]. the actual trajectories for link 1 and link 2 are shown in figs 8.a and 9.a, respectively. the system has transient rms error of (0.02445) for link 1 and (0.02333) for link 2, respectively as shown in figs 8.c and 9.c. the proposed nn self tuning control structure uses separate network for each link. this improves the obtained trajectory because any noise or disturbance if it is subjected to one link will not affect on the other. the results for the proposed nn self-tuning are shown in figs 8.b and 9.b. the transient rms tracking error is reduced to (0.02077) for link 1 and (0.037045) for link 2, respectively as shown in figs 8.c and 9.c. also the percentage error after 16 seconds of time is reduced from (1.17) to (0.014) and from (0.91) to (0.002) for link 1 and link 2, respectively. the desired circular trajectory performance of the proposed controller is shown in fig.10a. the obtained trajectory after two cycles of learning is presented in fig.10b. the simulation results are summarized in table 4. saad zaghlul saeed al-khwarizmi engineering journal, vol. 9, no. 1, p.p. 19-28 (2013) 24 fig. 7. simulation diagram for robot manipulator. table 3, robot’s links parameters [24]. link mass (kg) length (m) friction, μk kp kd 1 1 1 0.3 31 60 2 1 2 0.3 45 80 table 4, results of comparison for two-link robot manipulator. controller performance (rad) link 1 link 2 pid rms error 0.02445 0.02333 error after 16 sec. 0.01614 0.01521 error after 16 sec. % 1.17 0.91 proposed nn self tuning pid rms error 0.02077 0.037045 error after 16 sec. 1.9202e-04 3.7218e-05 error after 16 sec. % 0.014 0.002 saad zaghlul saeed al-khwarizmi engineering journal, vol. 9, no. 1, p.p. 19-28 (2013) 25 0 4 8 12 16 20 -1.6 -1.4 -1.2 -1 -0.8 -0.6 -0.4 -0.2 0 0.2 time, s po st io n, ra d desired position pid controller a 0 4 8 12 16 20 -1.4 -1.2 -1 -0.8 -0.6 -0.4 -0.2 0 0.2 time, s po si tio n, ra d desired position proposed controller b 0 4 8 12 16 20 -0.1 -0.05 0 0.05 0.1 0.15 proposed controller pid controller er ro r, ra d time, s c fig. 8. link 1 performance for desired trajectory. 0 4 8 12 16 20 0 0.5 1 1.5 2 time, s po si tio n, ra d desired position pid controller a 0 4 8 12 16 20 0 0.5 1 1.5 2 time, s po si tio n, ra d desired position proposed controller b 0 4 8 12 16 20 -0.05 0 0.05 0.1 0.15 0.2 time, s er ro r, ra d pid controller proposed controller c fig. 9. link 2 performance for desired trajectory. saad zaghlul saeed al-khwarizmi engineering journal, vol. 9, no. 1, p.p. 19-28 (2013) 26 1.8 2 2.2 2.4 2.6 2.8 3 3.2 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 x, m y, m a 1.8 2 2.2 2.4 2.6 2.8 3 3.2-0.6 -0.4 -0.2 0 0.2 0.4 0.6 x, m y, m b fig. 10. circular trajectory. a-trajectory for 20 sec.; btrajectory after 2 cycles of learning 6. conclusion neural network self tuning pid controller provides a different way to approach a control problem. this method focuses on what the system should do rather than trying to model how it works. one can concentrate on solving the problem rather than trying to model the system mathematically, if that is even possible. the application of a nn tuning to nominal controller designed using ziegler-nichols tuning rules is studied in this paper. it is shown that the addition of a nn tuning improves the response of a nominal pid controlled system through gradual increase in the controller gains. the advantage of the nn self tuning is its adaptively due to on-line training which provides auto-tuning and reducing the amount of tuning required. at the beginning of simulation, the error is maximum because the nn is not learned yet. but after 1 second of time, the error is reduced quickly and the robot starts follow the desired trajectory efficiently. simulation studies show that the proposed nn self tuning provides excellent tracking and robustness in the presence of system nonlinearity, since the nn is trained on-line, therefore any changes in system parameters will cause the nn to provide the appropriate change in the control signal to resume the effect. on the other side, we proved that the proposed controller is more efficient to control the robot manipulator to follow the desired trajectory compared to classical tuning method of pid controller. 7. references [1] spong, m. w. and vidiasagar, m., "robot modeling and control", wiley, new york, 1989, pp.231. [2] tao ai, jun-qi yu, yan-feng liu, and jiang zhou, "study on neural network self-tuning pid control for temperature of active solar house heating system", ieee 2nd international workshop on intelligent systems and applications, 2010, pp.1-4. [3] gawthrop, p. j. and nomikos, p.e., "automatic tuning of commercial pid controllers for single-loop and multiloop applications", ieee control systems magazine, vol. 10, 1990, pp.34-42. [4] jing-chug shen and huann-keng chiang, "pid tuning rules for second order systems", ieee 5th asian control conference, vol.1, 2004, pp.472-477. [5] han-pang huang and ching-hung lin, "a stable on-line self-tuning optimal pid controller for a class of unknown system", asian journal of control, vol. 9, no. 2, pp. 151-162, 2007. [6] al-zohairy, t. a., "adaptive control of nonlinear multivariable dynamical systems using rbf neural network", canadian journal on automation, control and intelligent systems, vol.2, no.1, 2001, pp.925. 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[16] chia-ju wu, "genetic tuning of pid controllers using a neural network model: a seesaw example", journal of intelligent and robotic systems, vol.25, 1999, pp.4359. [17] azevedo, ana b. and ruano, antonio e., "neural networks pid autotuning with online adaptation", 16th imags world congree, 2000. [18] kui zhang and xinyan an, "design of multivariable self-tuning pid controllers via quasi-diagonal recurrent wavelet neural network", 2nd international conference on intelligent human machine systems and cybernetics, vol.2, 2010, pp.95-99. [19] selami, b. and musa, a., "a new rbf network based sliding-mode control of nonlinear systems", international multi conference on computer science and information technology, vol.4, 2009, pp.1116. [20] ogata, k., "modern control engineering" , prentic-hall, inc., 2002. [21] howard demnth and mark beale, "neural network toolbox", the math works, inc., 2008, pp.327-337. [22] craige, john j., "introduction to robotics: mechanics and control", prentice-hell, inc., 2005, pp.180. [23] lehuy, h. and sybille, g., "matlab help ver.7", math works, inc., 2004. [24] heredia, a. and wen yu, "a high-gain observer-based pd control for robot manipulator", american control conference, chicago, usa, vol.4, 2000, pp.2518-2522. )2013( 1928، صفحة 1، العدد9مجلة الخوارزمي الھندسیة المجلد سعد زغلول سعید 28 التفاضلي بالشبكة العصبية لتتبع مسار ذراع روبوت-التكاملي-موالفة المسيطر التناسبي سعد زغلول سعید الخیاط جامعة الموصل /كلیة الھندسة /قسم ھندسة المیكاترونكس t@yahoo.comaalkhya: البرید األلكتروني الخالصة pidالطریقة بسیطة و تعطي قیم ثابتة للمعامالت مما یجعل المسیطر . pidطریقة لتولیف معامالت المسیطر nichols و zieglerاقترح الباحثان ة بالشبك pidلكي ینجز مسیطر متكیف، تم اقتراح في ھذا البحث موالفة المسیطر .ضعیفا في التكیف للتغیر في خواص المنظومة و ظروف التشغیل یمكن ان kp ،ki ،kdو ھي المكاسب pidان معامالت المسیطر . التقلیدي مع قابلیة التعلم للشبكة العصبیة pidو الذي یجمع المسیطر (nn)العصبیة التقلیدي لذراع الروبوت pidتم استبدال المسیطر . تولف أنیا بواسطة إخراج الشبكة العصبیة الذي ینتج تبعا للخطأ في إخراج المنظومة تحت السیطرة استخدمت المماثلة عبر الحاسوب اآللي و أظھرت النتائج ان ). تجاوز الحد(بالمسیطر المقترح لكي ینجز تتبع المسار بأقل خطأ و تحسین التصرف الدینامیكي . التقلیدي pidالمسیطر المقترح یمتلك تكیفا ذاتیا متفوقا على المسیطر (microsoft word 110117 \307\313\355\341) study the catalytic activity of degradation of department of chemistry (received 6 https://doi.org/10.22153/kej.2017.09.002 abstract the oxidative degradation of orange g dye catalyst was prepared by precipitation method. various physical and chemical properties of the synthesized phase. the ftir result showed the effect of calcination temperature for ceo band intensity compared to uncalcined ce nitrate sample. meanwhile, the diffuse spectra at 414 nm with an energy gap of 3.2 ev. out under various conditions such as, the effects reaction. the optimum conditions for the highest decolorization efficiency (100%) were achiev g dye with catalyst dosage of 1.5 g/l, ph 2, reaction temperature of 65 °c and 0.1 ml h keywords: cerium oxide, oxidation process, 1. introduction different shapes and sizes of semiconductor nanoparticles have been synthesized to be used in the application of advanced oxidation process generally, as the particles size reduces to nanostructure-scale then, the properties of material will dramatically changes recent advances in synthesis of nanostructures. the particle size of materials affects their basic properties such as lattice symmetry, cell parameters, and structural characteristics [2]. the nano structure of metal oxide unique chemical properties due to their limited size and high density of corner or edge surface sites . among different metal oxides, special attention has been focused on the formation and properties of cerium oxide is important as heterogeneous catalyst cerium oxide that has a wide band gap is consider a good semiconducting material which is fami for its catalytic properties. cerium, one lanthanide series exhibit both oxidation states and + 4 and has high ability for oxidation al-khwarizmi engineering journal,vol. 13, no. 1, p.p. catalytic activity of ceo2 catalyst for the oxidative orange g dye in aqueous solution atheel alwash chemistry/ collage of science/ al-nahrain university email: atheelalwash@yahoo.com 6 june 2016; accepted 20 september 2016) https://doi.org/10.22153/kej.2017.09.002 gradation of orange g dye by nanosized ceo2 catalyst has been performed in this study. the precipitation method. various characterization techniques were carried out to mical properties of the synthesized catalyst. the xrd result confirms well the formation of ceo the effect of calcination temperature for ceo2 was clearly observed due to reduction in band intensity compared to uncalcined ce nitrate sample. meanwhile, the diffused reflection spectra recorded at 414 nm with an energy gap of 3.2 ev. the decolorization of orange g dye by oxidation process were carried under various conditions such as, the effects of h2o2 dosage , ph, catalyst dosage and the temperature of the optimum conditions for the highest decolorization efficiency (100%) were achieved at 10 mg/l of orange of 1.5 g/l, ph 2, reaction temperature of 65 °c and 0.1 ml h2o2. cerium oxide, oxidation process, nanoparticles, heterogeneous catalyst. different shapes and sizes of semiconductor nanoparticles have been synthesized to be used in advanced oxidation process [1]. generally, as the particles size reduces to scale then, the properties of material will dramatically changes leading to recent advances in synthesis of nanostructures. the particle size of materials affects their basic ice symmetry, cell parameters, and structural characteristics [2]. can show unique chemical properties due to their limited size and high density of corner or edge metal oxides, special attention has been focused on the ion and properties of cerium oxide which is important as heterogeneous catalyst [3]. that has a wide band gap is consider which is familiar cerium, one of lanthanide series exhibit both oxidation states +3 oxidation/reduction reactions very easily. because of this excellent property cerium oxide is used in various applications such as catalytic converters, solid oxide fuel cells and oxygen buffers up to now various method have been developed for the synthesized of cerium oxide nanostructure, such as chemical vapor deposition, electrochemistry, templates, photoinduced conversion, biological synthesis. nanoparticles sizes of ceo2 have with different preparation method leading to produce different chemical, physical and optical properties of ceo2. the precipitation method has attracted the most attentions advantages of simple process, easy scale low cost [5]. cerium dioxide has been taken a great interest in the application of heterogeneous photocatalytic reactions. this was due to the properties of ceo as a semiconducting material that absorbs light in the near uv and also slightly in the visible region. however, there was no report for the cerium oxide as catalyst for the degradation of organics dyes using oxidation process khwarizmi engineering journal,vol. 13, no. 1, p.p. 110117 (2017) catalyst for the oxidative aqueous solution catalyst has been performed in this study. the characterization techniques were carried out to study the formation of ceo2 cubic was clearly observed due to reduction in reflection spectra recorded reflection the decolorization of orange g dye by oxidation process were carried and the temperature of ed at 10 mg/l of orange . because of this excellent property cerium oxide is used in various such as catalytic converters, solid oxide fuel cells and oxygen buffers [4]. up to now various method have been developed for the synthesized of cerium oxide , such as chemical vapor deposition, electrochemistry, templates, photoinduced conversion, biological synthesis. different have been synthesized with different preparation method leading to produce different chemical, physical and optical the precipitation method has attentions owing to the ess, easy scale-up and cerium dioxide has been taken a great interest heterogeneous photocatalytic this was due to the properties of ceo2 semiconducting material that absorbs light in the near uv and also slightly in the visible region. there was no report for the use of as catalyst for the degradation of oxidation process. as such, al-khwarizmi engineering journal atheel alwash al-khwarizmi engineering journal, vol. 13, no. 1, p.p. this report have been focused on the degradation of orange g dyes using nano ceo heterogeneous catalyst using oxidation process. different characterization techniques were conducted including characterization technique using x-ray diffraction, ftir, diffuse reflect spectra and afm technique. efforts made to investigate the effects of h2o2, solution acidity and the catalyst dosage. in this study, the stability of the catalyst is excluded as the aim was on the experimental work covering thorough characterization and process study under various conditions. 2. materials and methods the pure metal cerium nitrate purchased from bdh. meanwhile, hydrogen peroxide (30% analytical grade) was supplied from analar. the sodium carbonate as a precipitating agent was purchased from merck. the pollutant model orange g dye was obtained from fluka and its properties are listed in table 1. table 1, the structure and properties of orange g dye molecular structure other names acid orange 10 molecular weight 452.38 g/mol color index 16230 λmax 478 nm preparation method pure ceria oxide has been prepared by precipitation method technique according to the method similar to pradhan and parida, (2010). the sodium carbonate was used as a precipitating agent at room temperature. the conce the prepared sample for pure catalyst was 0.1 m. a known volume of pure oxide was na2co3 of 0.25 m was added into the until the ph reached to 9. at that ph, a khwarizmi engineering journal, vol. 13, no. 1, p.p. e been focused on the degradation of orange g dyes using nano ceo2 as heterogeneous catalyst using oxidation process. different characterization techniques were conducted including characterization technique ray diffraction, ftir, diffuse reflectance have been the effects of adding amount of in this study, the stability of the catalyst is excluded as the aim was focusing covering thorough characterization and process study under the pure metal cerium nitrate purchased from bdh. meanwhile, hydrogen peroxide (30% from analar. the sodium carbonate as a precipitating agent was purchased from merck. the pollutant model of orange g dye was obtained from fluka and its the structure and properties of orange g dye. pure ceria oxide has been prepared by precipitation method technique according to the method similar to pradhan and parida, (2010). the sodium carbonate was used as a precipitating agent at room temperature. the concentration of re catalyst was fixed at oxide was taken and of 0.25 m was added into the solution until the ph reached to 9. at that ph, a white precipitate solid was formed then the products were collected by filtration, washed with distilled water, and dried at 110 °c. finally, the prepared catalyst was denoted as ceo calcination at 500 °c for 4 h. 3. characterization techniques the characterization of the catalyst different analytical techniques was performed on the catalyst. x-ray diffraction (xrd) was used to study the crystalline phase oxide nanoparticles. the ftir spectroscopic analysis was carried out using bruker alpha spectrophotometer. meanwhile, the spectra of the solid samples were measured using the diffrection spectrophotometer elmer) with a wavelength range between 190 and 1,300 nm. the particle size analyzer was carried out by brookhaven instrument. roughness of the catalyst surface was using afm technique. reaction procedure and analytical method the experimental runs were carried out in a 250 ml conical flask as a reactor equipped with a magnetic stirrer and heater. water containing orange g dye (10 mg/l) was transferred to the glass reactor. thereafter, the catalyst was added to the solution. the temperature of the reaction mixture was controlled using heater to the desired value. hydrogen peroxide was added, the runs were conducted at 60 ◦c and the sampl taken at periodic intervals i.e. (10 min). maximum absorbance wavelength of orange g dye was carried out using spectrophotometric analysis to determine the maximum absorption of the dye which was fixed at 478 nm. law was used to calculate the concentration of the liquid samples based on measuring the absorbance of each sample at its maximum absorbance wavelength. after a certain period of catalytic reaction, a liquid sample was withdrawn and centrifuged at 3000 rpm to separate th catalyst from liquid sample. the catalytic activity represented by the color removal was calculated based on equation (1) [7]: decolorization ef�iciency % � where, cₒ is concentration of dye the concentration of dye in (mg/l) reaction time and t (min). khwarizmi engineering journal, vol. 13, no. 1, p.p. 110117(2017) precipitate solid was formed then the products were collected by filtration, washed several times with distilled water, and dried at 110 °c. finally, prepared catalyst was denoted as ceo2 after its ques acterization of the catalyst with iques was performed ray diffraction (xrd) was crystalline phase of cerium the ftir spectroscopic analysis was carried out using bruker alpha ter. meanwhile, the reflection spectra of the solid samples were measured using otometer by (perkin range between 190 and the particle size analyzer was carried out by brookhaven instrument. the alyst surface was checked analytical method the experimental runs were carried out in a 250 ml conical flask as a reactor equipped with a magnetic stirrer and heater. water containing was transferred to the glass reactor. thereafter, the catalyst was added to the solution. the temperature of the reaction mixture was controlled using heater to the desired value. hydrogen peroxide was added, the runs c and the samples were taken at periodic intervals i.e. (10 min). the maximum absorbance wavelength of orange g dye was carried out using spectrophotometric to determine the maximum absorption of the dye which was fixed at 478 nm. beer-lambert calculate the concentration of the liquid samples based on measuring the absorbance of each sample at its maximum absorbance after a certain period of catalytic reaction, a liquid sample was withdrawn and centrifuged at 3000 rpm to separate the solid the catalytic activity represented by the color removal was calculated � � ������� � � 100 …(1) concentration of dye in (mg/l), ct is in (mg/l) at different atheel alwash al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 110117(2017) 4. result and discussion 4.1. x-ray diffraction fig. 1 shows the indexed xrd pattern for the prepared ceo2 sample. the ceo2 show high crystalline structure of peaks that confirms the formation of cubic phase ceo2 samples. the dspacing values of the cerium oxide sample matches well the standard code of 96-900-9009. the characteristic reflection at 2θ values were at 28.78°, 33.27°, 47.67°, 56.48°, 59.19°, 69.53° and 76.82° respectively. this result was in agreement with chelliah et al., (2012) and teo et al., (2014). as the xrd result confirms the formation of cerium oxide phase this indeed improve the success of preparation method. fig. 1. x-ray diffraction of ceo2 4.2. fourier transformed infrared spectroscopy (ftir) analysis the ft-ir spectrum of the ceo2 annealed at 500 °c is shown in fig. 2 . fig.2 (a), shows the broad absorption band located around 3429 cm –1 corresponds to the o-h stretching vibration of residual water and hydroxyl groups, while the absorption band at 1647cm –1 can be attributed to the o-h vibration in absorbed water on the sample surface. similar results were detected with kumara et al., (2013). the effect of calcination temperature for ceo2 was clearly observed due to reduction of those band intensity compared to uncalcined ce nitrate sample in fig 2 (b). in fig. 2 (b), chelliah et al., (2012) reported that the band at 1384 cm –1 referred to n-o stretch due to the presence of nitrate , this result confirmed our uncalcined cerium nitrate at a band around 1362 cm –1 however this band was completely disappear after calcination due to the complete dissociation of nitrate compounds. the peaks ranging from 750 to 400 cm-1 was related to metal-o stretching vibration [10]. the band at 844 cm –1 referred to (ce-o) metal-oxygen bond. fig. 2. fourier transformed infrared spectroscopy of (a) ceo2 calcined at 500 °c (b) uncalcined cerium nitrate. 4.3. uv-vis diffuse reflectance spectra analysis and particle size analyzer the diffuse reflectance spectra of ceo2 nanoparticles were recorded in fig. 3 (a) using a uv-vis diffuse reflectance spectra over the wavelength from 200-1200 nm. the cerium oxide nanoparticles shows a reflection spectra at 414 nm. the optical band gap energy of the prepared sample was detected in the sudden fall region at a certain wavelength. the band gap energy value was determined from the extrapolation of the straight line for the graph figured between the [ln [(rmax-rmin)/(r-rmin)]]^2 versus photon energy (hv) (as abscissa) kumar et al. (1999) as in fig. 3 (b). channei1 et al., (2014) reported that the energy gap of ceo2 nanoparticles was 3 ev. khan et al., (2013) reported that the energy gap of ceo2 nanoparticles was about 4.16 ev. meanwhile chaiwichian et al., (2012) reported that the energy gap of ceo2 nanoparticles was 2.77 ev with particle size of 5-10 nm. the optical properties of the solid catalyst affected directly by the preparation method thus affect its energy band gap. fig.3 (c) presents the particles size of ceo2 catalyst that was analyzed by the particle size analyzer. the result shows that the particle size of ceo2 was about 2.03 e +3 nm. according to literature, different reports have been reported the particle size of cerium oxide with different values depending on various types’ techniques such as sem, tem or particle size analyzer. several factors can effects on particle size of the materials such as the preparation methods, calcination temperatures and raw materials used during the preparation methods etc…. atheel alwash al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 110117(2017) fig. 3. uv-vis diffuse reflectance spectra (a), band gap energy (b) and (c) particle size analyzer 4.4. atomic force microscopy (afm) fig. 4 shows the afm 3d image of ceo2 catalyst calcined at 500 °c. the image detects a separated conical nano columnar structure with measured roughness of (area ra 0.825 nm) and (area rms 1.03 nm). the measured roughness reported earlier for pure ceo2 thin film by durrani et al. (2008) with (area ra 2.38) and (area rms 3.11). fig. 4. afm technique (3-d) image of ceo2 4.5. the optimum reaction condition for the decolorization of orange g dye 4.5.1.effect of ph the effect of ph on the catalytic activity of ceo2 nanoparticles for the decolorization of orange g dyes with an initial dye concentration of 10 mg/l over a ph range of 2–10. the ph of the dye solution was adjusted by adding suitable amounts of 1m hcl and naoh. the decolorization efficiency at different ph solutions is shown in fig. 5. the results show that the maximum decolorization efficiency of 100% was obtained at a ph of 2 after 60 min of oxidation process. at ph 5 and 10, the decolorization of orange g dye was almost the same range about 13%. this higher catalytic activity at ph 2 was referring to the higher •oh radicals generated. furthermore, as the orange g dye is an anionic dye, its adsorption mainly performed via an electrostatic interactions between the positive ceo2 surface and orange g dye anions, leading to a maximum extent at ph 2. bokare et al., (2008) also reported that higher catalytic activity for orange g dye i.e. 99% was achieved at ph 2 using bimetallic nanoparticles oxide of fe-ni catalyst. on other hand, the lower catalytic activity at higher ph values i.e. 5 and 10 could be referred to the self-decomposition reaction of h2o2 to h2o and o2. fig. 5. the effect of ph on the decolorization efficiency orange g dye at initial dye concentration 10 mg/l, 0.15 g/l catalyst loading, reaction temperature 65 °c and 0.1 ml h2o2/100ml reaction volume. 4.5.2. effect of catalyst dosage the effect of catalyst dosage on the decolorization efficiency of orange g dye was investigated with different catalyst dosage ranging from 0.5 g/l up to 2 g/l with reaction condition of 10 mg/l concentration of dye, 0.1ml h2o2/100ml of reaction and solution acidity of 2.0 for 60 min of reaction time as in fig. 6. atheel alwash al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 110117(2017) fig. 6. effect of catalyst dosage on the decolorization efficiency orange g dye at initial dye concentration 10 mg/l, ph 2, reaction temperature 65 °c and 0.1 ml h2o2/100ml reaction volume. before the starting of oxidation reaction, 30 min of mechanical stirring was observed until adsorption-desorption equilibrium was reached. the results showed that the adsorption rate was increase from 11% to 60% with an increase in catalyst dosage ranging from 0.5 g/l to 2 g/l, respectively. the presence of extra active sites and higher effective surface area enhance the adsorption rate in cerium oxide catalyst [17] as in fig. 6. with the start of oxidation reaction, the catalytic activity was increased from 14% to 100% for catalysts loading of 0.05 and 1 g/l respectively. however, as the catalyst dosage was further increase up to 2 g/l, insignificant difference in catalytic activity was notice after 60 min of oxidation reaction i.e. 100%. the synergistic effect between the heterogeneous catalyst/h2o2 system enhance the generation of radicals thus, improve the catalytic activity . slavova et al., (2014) reported that higher catalyst loading in solution would result in higher dye removal efficiency. however, the variation in optimum values of the catalyst dosage based on the process environment, the structure of dye molecules and the catalyst properties. 4.5.3. effect of temperature reaction temperature is another important process parameter that has a significant effect on catalytic activity during the oxidation process. the effect of reaction temperature on the decolorization efficiency of orange g dye was detected throw a series of experiments within the catalyst loading used of 1.5 g/l, 10 mg/l initial concentration of dye, 0.1 ml h2o2/100 ml of reaction and ph of 2.0 by varying temperature from 25 °c to 65 °c as in fig. 7. after 30 min of mechanical stirring between the nanoparticles of ceo2 and dye solution, the adsorption rate of orange g dye was decreased as temperature increase. mafra et al., (2013) reported that the fall in the adsorption capacity at elevated temperatures could be ascribed to the escape of the dye molecules from the catalyst surface and re-enters the liquid phase as an increase in temperature caused an increase in the speed of molecules. consequently, as the oxidation reaction was started, the decolorization of orange g dye was significantly influenced by the reaction temperature and the decolorization was accelerated from 59% to 100% by a rise in temperature from 25 °c to 65 °c. this is because higher temperature increased the reaction rate between hydrogen peroxide and the catalyst, thus increasing the rate of generation of oxidizing species such as ˙oh radical. fig. 7. the effect of reaction temperature on the decolorization of orange g dye under initial dye concentration 10 mg/l, catalyst loading 1.5 g/l, ph 2 and 0.1 ml h2o2/ 100 ml of reaction volume. effect of h2o2. the highly solubility and low volatility of hydrogen peroxide in h2o caused the excessive decomposition rate at higher temperature. previously muruganandham et al. (2007) reported the low bond energy of o-o bond in h2o2 solution with about (213 kj/mol) in comparison to hydroxyl bond in water (418 kj/mol). consequently, the formation of radicals with the existence of hydrogen peroxide was more rapidly and considerably improved the activity of the reaction. 4.5.4. effect of h2o2 dosage the catalytic activity based on color removal of orange g dye was examined by changing the concentrations of hydrogen peroxide in the dye solution i.e. 0.05, 0.1 and 0.15 ml of h2o2/100 ml atheel alwash al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 110117(2017) of reaction volume within the catalyst loading used of 1.5 g/l , 10 mg/l initial concentration of dye, ph of 2.0 and reaction temperature of 65 °c as in fig. 8. as the mechanical stirring was started, a certain amount of hydrogen peroxide was added into the reaction solution and the oxidation reaction was started. the h2o2 was consider as an external source and its addition into the reaction increase the possibility of radicals generation during the oxidation process. the optimum efficiency of 100% was found at 0.1 ml after 60 min of the reaction time as shown in fig. 8. above the optimum value, the decolorization efficieny of orange g dye was dropped to 50% at 0.15 ml h2o2. this reduction in catalytic activity as the amount of hydrogen peroxides increased was ascribed to its extra amount in the reaction that acts as scavengers to hydroxyl radicals [21]. fig. 8. effect of h2o2 addition on the decolorization of neutral red dye under several conditions. (initial dye concentration 10 mg/l, catalyst loading 1.5 g/l, ph 5.5 and reaction temperature of 60 °c). 5. conclusion the heterogeneous catalyst ceo2 were successfully synthesized using precipitation method. characterization results of xrd show high crystalline structure of peaks that confirms the formation of cubic phase ceo2 samples. ftir technique detected the effect of calcination temperature on the formation of ceo2 due to the reduction of band intensity compared to uncalcined ce nitrate sample. the uv-vis diffuse reflectance spectrum for ceo2 demonstrated the presence of optical band gap due to the sudden reduction in reflection spectra of the sample at 414 nm with an energy gap of 3.2 ev. meanwhile the afm 3d image of ceo2 calcined at 500 °c reveals the formation of well separated conical nano columnar structure with measured roughness value of 1.03 nm. a process behavior of the catalyst was also successfully elucidated. the best conditions for the highest decolorization efficiency (100%) were achieved at 10 mg/l of orange g dye, catalyst loading of 1.5 g/l, ph 2, reaction temperature of 65 °c and 0.1 ml h2o2/100 ml solution. hence, the prepared cerium oxide catalyst under oxidation reaction is a good environmental heterogeneous catalyst and can be widely used in the application of wastewater treatment method for organic dyes in effluents. 6. references [1] pouretedal, h.r., kadkhodaie, a., “synthetic ceo2 nanoparticle catalysis of methylene blue photodegradation: kinetics and mechanism”, chinese journal of catalysis, vol. 31(11), (2010). [2] zamiri, r., ahangar, h.a., kaushal, a., zakaria, a., “dielectical properties of ceo2 nanoparticles at different temperatures”, plos one, vol. 10 (4), (2015). [3] farzaneh, f. aznd najafi, m., “synthesis and characterization of cr2o3 nanoparticles with triethanolamine in water under microwave irradiation”, journal of sciences, islamic republic of iran, vol. 22(4), pp.329-333, (2011). [4] chelliah, m. rayappan, j.b. and krishnan, u.m., “synthesis and characterization of cerium oxide nanoparticles by hydroxide mediated approach”, journal of applied science, vol. 12 (16), pp.1734-1737, (2012). [5] liu, y.h., zuo, j.c., ren, x.f., yong, l., “synthesis and characterization of cerium oxide (ceo2) nanoparticles by the precipitation method”, metabk, vol. 53(4), pp.463-465, (2014). [6] pradhan, g.k., parida, k.m., “fabrication of iron-cerium mixed oxide: an efficient photocatalyst for dye degradation”, international journal of engineering, science and technology, vol. 2 (9), pp. 53-65, (2010). [7] alwash, a. h., abdullah , a.z., ismail, n., “elucidation of reaction behaviors in sonocatalytic decolorization of amaranth dye in water using zeolite y co-incorporated with fe and tio2”, advances in chemical engineering and science, vol. 3, pp.113-122, (2013). [8] teo, s.h., rashid, u. and taufiq-yap, y, h. “heterogeneous catalysis of transesterification of jatropha curcas oil over calcium–cerium atheel alwash al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 110117(2017) 116 bimetallic oxide catalyst”, rsc advances, vol. 4, pp.48836, (2014). [9] kumara, e., selvarajan, p., muthuraj, d., “synthesis and characterization of ceo2 nanocrystals by solvothermal route”, materials research, vol.16(2), pp.269-276, (2013). [10] mane, v.b., mahind, l.h., jadhav, k.d., waghmode, s.a. and dagade, s.p., “structural characterization of nanosized fe2o3-ceo2 catalysts by xrd, edx and tem techniques”, carbon – science and technology, vol. 5/2, pp.260 – 264, (2013). [11] kumar, v., sharma, s., sharma, t. p. and singh, v., “band gap determination in thick films from reflectance measurements”, optical materials, vol. 12, pp.115-119, (1999). [12] channei1, d., inceesungvorn, b., wetchakun, n., ukritnukun, s., nattestad, a., chen, j. & phanichphant, s., “photocatalytic degradation of methyl orange by ceo2 and fe–doped ceo2 films under visible light irradiation”, scientific reports, vol. 4, pp.5757, (2014). [13] khan, s.b., faisal, m., rahman, m.m., akhtar, k., asiri, a.m., khan , a., alamry, k.a., “effect of particle size on the photocatalytic activity and sensing properties of ceo2 nanoparticles”, international journal of electrochemical science, vol. 8, pp.7284 – 7297, (2013). 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[18] slavova, i. a., stoyanova, m.k., christoskova, s.g., vanina v. ivanova, v.v., “study on the catalytic activity of cobalt and iron-cobalt mixed oxides for the oxidative degradation of acid orange 7 in aqueous solution”, journal of international scientific publications: ecology and safety, vol.8, pp.469-478, (2014). [19] mafra, m.r., igarashi-mafra, l., zuim, d.r., vasques, e.c., and m. a. ferreira, m.a., “adsorption of remazol brilliant blue on an orange peel adsorbent”, brazilian journal of chemical engineering, vol. 30 (03), pp.657 – 665, (2013). [20] muruganandham, m., yang, j. s. and wu, j. j., “effect of ultrasonic irradiation on the catalytic activity and stability of goethite catalyst in the presence of h2o2 at acidic medium”, industrial and engineering chemistry research, vol. 46, pp.691-698, (2007). [21] hassan, h. and hameed, b. h., “oxidative decolorization of acid red1 solutions by fe–zeolite y type catalyst”, desalination, vol. 276, pp.45-52, (2011). ا��� ���ش ��� ���� 1، ا ��د�13��� ا ��ارز � ا ������ ا ،2017( 117-110( 117 ����� ���%$� ا#ورا! ج ��ا� &���' �( ��)* � درا�� +�(ءة ا *�.,�م او+*(,� +�( ا#+*�ة أ��� ���ش �م /��� ا������ء���� ا�%$#"!/ ��� ا�&�' atheelalwash@yahoo.com ()ا�.#"ا,��+#و: ��2� ا �د ا���#;�درا;� :���� ��819 6.7� ا,ورا(4 ج 2� ا�.01$-ف "'��م او ��"ا�%�(�ي ط� :���� ا, �-ة 2" @a7�2ba1&ي اcوا� ��%d9 �9@ !: e�;#+ا� ����: f"#ط . g%dا�� ba1ا�� �2%� h�ij9 �9 ال �د ا���%���� ا��1lت و&%$� ا��%n9 ام :-ة-i+;�2xrd ، �"رcة ا��nا� #$p& وafm ، h�ij9 �ة ا���8� 2� ftirا,وا7# ا�#ا82� i+;�2-ام pq ;�و���س �طdiffuse reflectance spectra . s+.tا �د ا���%���� ا��1l4 اu�+) -"�� م او��y 9#ددات ftir ـ4u�+) s%�2 !�w (q ا�. (�pح �9�"! ط�ر ا���#": ba1���� ا�1#ار"� �&���tz9# ا�� �م او ��"-"#���� ��uا,وا7# ا������ [n9 s)� (+\�# وا� �����2دة ا,و�� �)ر�n&ا� ��&��� )s"#+"�) م�"#�;( . 4u�+) أظ$#تdiffuse reflectance spectra د��دا :% و'�w414nm @ة ط���pq ار-n&3.2و ev . ����a yءة ازا�� ا�: #l�.& #�tz9 �$� (+ا� [:�a+�6#ات ا�+& !& -"-���&] ا����:ا��g%d �9 درا;� ا��� h�ij+ا� ���2�ا;+���ل :� sل و�`a ن [:�a+و&%$� ا� ،�c���&] ا����:�و7�s ا�y . ودر'� ا�1#ارة، ��� ا���&] ا����:-، ��� ا�$�-رو'�! �2#و ��"-، در'� ا��1�و �(s ا:��a yءة � ١٠٠ % �c��w �'ا����:، 2٢-ر [&���d.6@ ١٠٠/&] ھ�-رو'�! �2#و ��"٠.١، �+#/\�١.٥و ��� ا�� (uا2+-ا b� #9 g& [:�a+ا� �pw !& [&١٠ j��"� ٦٥ودر'� w#ارة ، �+#�/&l& �'ل در`a٦٠ [:�a+ا� sو� !& �nد�� . 7383 al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 11, no. 1, p.p. 7383 (2015) catalytic cracking of iraqi vacuum gasoil using large and medium pore size of zeolite catalysts ameel mohammed rahman* mohanned h. salman** khalid waleed hammed*** *,**,***department of biochemical engineering/ al-khawarizmi college of engineering/ university of baghdad *e-mail: explorerxp50@yahoo.com ** e-mail: mohanned12345@yahoo.com *** e-mail: kwhameed74@yahoo.com (received 12 january 2014; accepted 17 december 2014) abstract the catalytic cracking conversion of iraqi vacuum gas oil was studied on large and medium pore size (hy, hx, zsm-22 and zsm-11) of zeolite catalysts. these catalysts were prepared locally and used in the present work. the catalytic conversion performed on a continuous fixed-bed laboratory reaction unit. experiments were performed in the temperature range of 673 to 823k, pressure range of 3 to 15bar, and lhsv range of 0.5-3h-1. the results show that the catalytic conversion of vacuum gas oil increases with increase in reaction temperature and decreases with increase in lhsv. the catalytic activity for the proposed catalysts arranged in the following order: hy>hx>zsm-11>zsm-22 the product distribution depends greatly on the temperature and on the catalyst type. a higher hydrocarbon yields was obtained for hy zeolite catalyst. the selectivity towards high octane number compounds for the proposed catalysts are arranged in the following order: hy>hx>zsm-11>zsm-22 the cracking conversion is improved by increasing reaction pressure up to 15 bar. the simulated experiments of the catalytic cracking process show that the higher conversion and more desired products can be achieved to conventional feeds. keywords: catalytic cracking, vacuum gas oil, zeolite, hy, hx, zsm-11, zsm-22. 1. introduction with the continuously increasing in demands for light hydrocarbon products due to the increases in industrialization and population as well as crude oil resources limitations, have caused a strong interest for the development of new and alternative methods for liquid fuels production. currently, the catalytic cracking units are available and become more prevalent due to the declining availability and higher price for light crudes (jorge ancheyta, 2011; lawrie 2011; fonseca et al, 2011; siddiqui et al., 2011; mario l. 2010). it is the most used process in the production of lpg and gasoline from vacuum gas oil or atmospheric residue (samar et al., 2008; caeiro et al., 2007). the process of catalytic cracking of a hydrocarbon feedstock comprises the catalytically scission of the c-c bonds cracked in a reactor by contact with a cracking catalyst to produce cracked products and unconverted cracked products and feed are withdrawn as a vapor stream and fractionated in a fractionator column to produce a plurality of products including a liquid slurry oil product containing hydrocarbons (al-hassani, 2007; gauw et al., 2002; mohsen et al., 1995). the formation of products in catalytic cracking process is accomplished by both primary and secondary reactions. primary reactions are ameel mohammed al-khwarizmi engineering journal, vol. 11, no. 1, p.p. 7383(2015) 74 designed as those involving the initial carboncarbon bond scission and the immediate neutralization of carbonium ion (samar et al., 2008; occelli, 2007; laxmi et al., 2003; gauw et al., 2002). the mechanism of carbonium ions formation initially beginning by a small amount of thermal cracking of n-paraffins to form olefins. these olefins add a proton from the catalyst to form large carbonium ions which decompose according to the beta rule (carbon-carbon bond scission takes place at the carbon in the position beta to the carbonium ions and olefins) to form small carbonium ions and olefins. the small carbonium ions propagate the chain reaction by transferring a hydrogen ion from an n-paraffin to form a small paraffin molecule and new large carbonium ion. thus the chain repeats itself continuously (corma et al., 1995; samar et al., 2008; thomas, 1949; mohan et al., 2004). even through the basic mechanism is essentially the same, the manner and extent of response to catalytic cracking differs greatly among the various hydrocarbons types and type of catalyst used. cracking catalysts are divided into three classes: (1) acid-treated natural aluminosilicates, (2) amorphous synthetic silica-alumina combinations, and (3) crystalline synthetic silicaalumina catalysts called zeolites or molecular sieves (mario, 2010; jiří et al., 2011). zeolites are widely used as catalysts for cracking of petroleum feedstocks. the advantages of the zeolite catalysts are: (1) higher activity, (2) higher gasoline yields at a given conversion, (3) production of gasoline containing a larger percentage of paraffinic and aromatic hydrocarbons, (4) lower coke yield (and therefore usually a larger throughput at a given conversion level), (5) increased isobutane production and (6) ability to go to higher conversions per pass without over cracking (lawrie, 2011; gary, 2001; ibrasheva and zhubanov, 2000). zeolites such as zsm-11, zsm-12, mordenite, y-zeolite, l-zeolite, b-zeolite and silicoaluminophosphates (sapo-n), as well as zsm-22, have been studied extensively as the catalysts for catalytic cracking (graça et al., 2011, 2009; gang et al., 2008; samar et al., 2008; laxmi; et al., 2003; arthur et al., 2002; muñoz et al., 2000;). the dimensions and shape of zeolite pores is strongly influenced the activity and selectivity of catalytic conversion. the shape selectivity exhibited by zeolites can be classified as (i) reactant shape selectivity, (ii) product shape selectivity, and (iii) transition state shape selectivity depending upon whether reactant diffusion, product diffusion, or the transition state is a limiting step. besides these classic shape selectivity mechanisms inside the zeolite micropores, pore mouth catalysis is a special type of transition state shape selectivity involving adsorption and catalysis in the pore openings only (laxmi et al., 2003; al-khattaf et al., 1999-2002). generally, large and medium pore sizes are widely used as cracking catalysts. the catalyst composition comprising a primary cracking component, such as zeolite y, and a mesoporous aluminophosphate material which includes a solid aluminophosphate composition modified with at least one element selected from zirconium, cerium, lanthanum, manganese, cobalt, zinc, and vanadium (al-hassany, 2009; mohan et al., 2004). the mesoporous aluminophosphate material has a specific surface area of at least 100 m2/g, an average pore size less than or equal to 100å, and a pore size distribution such that at least 50% of the pores have a pore diameter less than 100å (arthur et al., 2002). corma et al., 1995 explained that the size of the catalyst pores which are larger than 6 å diameter allows to process relatively high-boiling oil fractions and petrochemical bases. also he concluded that faujasite is used for carrying out the cracking and hydrocracking of vacuum gasoil. zeolite pores size is strongly effect the product distribution, and this property has been studied extensively by many authors (al-hassany, 2009; al-khattaf et al., 1999-2002; schwan et al., 2000; henrique et al., 1997). the main objective of the present work is to study the cracking activity and selectivity as well as products distribution of zsm-11, zsm-22, hy and hx catalysts and the effect of limited ranges of operating conditions (temperature, lhsv, and operating pressure) on the vacuum gas oil transformation in a fixed bed continuous laboratory reaction unit. ameel mohammed al-khwarizmi engineering journal, vol. 11, no. 1, p.p. 7383(2015) 75 2. experimental work 2.1. materials 2.1.1. feedstock vacuum gas oil (vco) supplied from al-dura refinery was used as a feedstock in transformation experiments. the properties of vco are listed in table 1. table 1, properties of straight run light naphtha. specific gravity @ 15°c 0.893 pour point, °c 48 vanadium content, ppm 3 nickel content 2 aniline point, °c 70 ccr, wt% 1 sulfur content, wt% 1.5 ibp, °c 320 fbp, °c 550 composition wt.% saturated/ non-cyclic 46.9 cyclic/ non aromatics 22.5 monoaromatic 25.1 diaromatic 4.6 triaromatic 0.6 tetraaromatic 0.3 2.1.2. nitrogen gas high purity (99.999 vol.%) of nitrogen gas supplied from the local market was used in the present work. 2.1.3. ammonium zsm-11, zsm-22, hy and hx zeolites ammonium zsm-11, zsm-22, hy and hx zeolites supplied as a powder from zeolyst international company. they were used in the preparation of the proposed catalysts. the properties of these zeolites are listed in table 2. table 2, properties of ammonium zeolite powder. sio2/al2o3 mole ratio nominal cation form na2o weight % surface area, m2/g hy 5 ammonium 0.08 660 hx 2.5 ammonium 0.02 352 zsm-11 21 ammonium 0.01 387 zsm-22 31 ammonium 0.05 395 2.2. catalyst pelleting 100 g of ammonium zsm-11, zsm-22, hy and hx zeolites powders were shaped as pelletes with dimensions of 3mm×5mm using a laboratory scale pelleting machine (model tdp-1.5 from minhua pharmaceutical machinery co., limited). the final forms were dried at 110°c and stored in an evacuated place. 2.3. hy zeolite preparation the dried zeolite pellets were calcinated at 500°c for 3 hrs in a furnace with nitrogen. the calcinated catalyst pellets were then reduced with hydrogen at 350°c for 3 hrs (al-hassani, 2007). the properties of the prepared zsm-22, zsm-11, hy and hx zeolite catalysts are listed in table 3. table 3, properties of the zsm-11, zsm-22, hy and hx zeolites. surface area m2/g bulk density g/cm3 pore volume, cm3/g zsm-22 399 0.510 0.37 zsm-11 332 0.532 0.115 hy 662 0.592 0.96 hx 425 0.588 0.521 2.4. catalytic cracking reaction unit catalytic cracking experiments were conducted in a continuous fixed bed reactor laboratory scale unit. figure 1 shows the schematic diagram of this unit. it consist of feed tank (t-301), gas flow meter and controller (fcv), feed pump (p-301), evaporator (m-301), fixed bed reactor (r-301), high pressure separator (e-301), low pressure separator (s-301), and an appropriate heating system (h-301). the reactor was heated and controlled automatically with computer control software and by four steel jacket heaters using chromal alumel thermocouple (type k). ameel mohammed al-khwarizmi engineering journal, vol. 11, no. 1, p.p. 7383(2015) 76 fig. 1. schematic diagram of laboratory continuous fixed bed reaction unit. r-301 tubular reactor p-301 feed pump fcv-301 fcv-302 fcv-303 fcv-304 mass flow controller t-301 feed tank e-301 condenser s-301 separator m-301 mixer h-301 heater prv-301 pressure relief valve piping and instrument flow diagram laboratory reaction unit university of baghdad al-khawarizmi college of engineering department of biochemical engineering ameel mohammed al-khwarizmi engineering journal, vol. 11, no. 1, p.p. 7383(2015) 77 2.5. catalytic cracking experiments the catalytic activity experiment was performed by charging 30 cm3 of fresh catalyst in the reactor and between two layers of inert material (glass balls). in the beginning of each experiment, the reactor was flashed with nitrogen 2 l/h for 1 h to purge the air from the system, then the reactor is heated to the desired temperature. the reaction pressure was adjusted by regulating nitrogen pressure. a pre-specified flow rate of vacuum gas oil was set on, vaporized in the evaporator and the vapor was mixed with the nitrogen in the mixing unit at a specified flow rates. the mixture entered the reactor from the top, distributed uniformly and reacted on the catalyst. the gaseous products passed through the high pressure separator and the final condensates were collected in the low pressure separator only after steady state operation was established and the initial products were discarded. the catalytic cracking reaction conditions employed are temperature range 400-550°c, liquid hourly space velocity (lhvs) range 0.5-3h-1, the pressure was ranging from 3-15 bar. 2.6. gas chromatographic analysis the collected products (liquid and gas) were analysis into their components by gas chromatographic (gc) analysis using shimadzu gc model 2014a with fid detector. 3. results and discussion the results of catalytic conversion runs of iraqi vacuum gas oil (ivgo) are discussed in this section in order to evaluate the catalyst performance. the purpose of the present work is to choose the study the effect of operating conditions on the proposed catalysts activity and stability. the catalytic cracking conversion involves six main reactions, gaseous product formation, isomerizaation, n-paraffin formation, olefination, cycalization and aromatization. in this section, discussions were built upon the results of these reactions. 3.1. effect of temperature the effect of temperature on ivgo transformation is shown in figs. 2-5. it is clearly temperature dependent. in the temperature range of 673 to 823k the conversion is increases over the prepared zsm-22, zsm-11, hy, and hx catalysts. the increases in the activity may be due to the increases in the concentration of the active sites and as the reaction temperature increases the concentration increases leads to increase in the cracking rate. this phenomenon was observed also by other researchers (samar, 2008; alkhattaf et al., 1999-2002; schwan et al., 2000; corma et al., 1995). it can also be observed that the values of the cracking conversion over the prepared catalysts take the following order: hy > hx > zsm-22 > zsm-11 the higher activity for hy catalyst compared with the other prepared catalyst may be due to the effect of catalyst acidity. hy zeolite has a high acidity as reported by many studied (al-hassany, 2009; gauw et al., 2002; al-khattaf et al., 2002) and the order of acidity decreases in the same manner so a lower conversion is observed for zsm-11 catalyst. 0 10 20 30 40 50 60 70 650 700 750 800 850 temperature, k c o n ve rs io n , w t. % zsm-22 zsm-11 hy hx fig. 2. catalytic cracking conversion vs. temperature at lhsv of 0.5h-1 and pressure of 3bar. 0 10 20 30 40 50 60 650 700 750 800 850 temperature, k c o n ve rs io n , w t. % zsm-22 zsm-11 hy hx fig. 3. catalytic cracking conversion vs. temperature at lhsv of 1h-1 and pressure of 3bar. ameel mohammed al-khwarizmi engineering journal, vol. 11, no. 1, p.p. 7383(2015) 78 0 5 10 15 20 25 30 35 40 650 700 750 800 850 temperature, k c o nv er si o n , w t.% zsm-22 zsm-11 hy hx fig. 4. catalytic cracking conversion vs. temperature at lhsv of 2h-1 and pressure of 3bar. 0 5 10 15 20 25 30 35 650 700 750 800 850 temperature, k c o n ve rs io n , w t. % zsm-22 zsm-11 hy hx fig. 5. catalytic cracking conversion vs. temperature at lhsv of 3h-1 and pressure of 3bar. 3.2. effect of lhsv figures 6 9 show the change in ivgo transformation as a function of lhsv. the liquid hourly space velocity taken as the ratio between the volumetric flow rate of ivgo and catalyst volume (the contact time is 1/lhsv). it can be observed from these figures that as the lhsv increases the catalytic conversion decreases so the rates of cracking decreases. this many be attributed to the fact that with decreasing lhsv more time is exerted to the molecules of ivgo to react on the active sites. the same order is observed for the prepared catalyst and this is may be attributed to the effect of pore diffusion. a high pore volume was measured for hy zeolite and lower value was measured for zsm-11 and as listed in table 2. the same observations were reported in other works (graça et al., 2009; caeiro et al., 2007; laxmi et al., 2003; arthur et al., 2002; al-khattaf et al., 1999-2002). 0 5 10 15 20 25 30 35 0 0.5 1 1.5 2 2.5 3 3.5 lhsv, h-1 c o n ve rs io n , w t. % zsm-22 zsm-11 hy hx fig. 6. catalytic cracking conversion vs. lhsv at temperature of 673k and pressure of 3bar. 0 5 10 15 20 25 30 35 40 45 50 0 0.5 1 1.5 2 2.5 3 3.5 lhsv, h-1 c o n ve rs io n , w t. % zsm-22 zsm-11 hy hx fig. 7. catalytic cracking conversion vs. lhsv at temperature of 723k and pressure of 3bar. 0 10 20 30 40 50 60 0 0.5 1 1.5 2 2.5 3 3.5 lhsv, h-1 c o n ve rs io n , w t. % zsm-22 zsm-11 hy hx fig. 8. catalytic cracking conversion vs. lhsv at temperature of 773k and pressure of 3bar. ameel mohammed al-khwarizmi engineering journal, vol. 11, no. 1, p.p. 7383(2015) 79 0 10 20 30 40 50 60 70 0 0.5 1 1.5 2 2.5 3 3.5 lhsv, h-1 c o nv er si o n , w t. % zsm-22 zsm-11 hy hx fig. 9. catalytic cracking conversion vs. lhsv at temperature of 823k and pressure of 3bar. 3.3. effect of pressure the effect of reaction pressure on the ivgo catalytic conversion is shown in fig. 10. as the reaction pressure increases ivgo conversion increases and over the four prepared catalysts. the increase in operating pressure is probably leads to increase in hydrocarbon surface coverage area leading to increasing the concentration of carbenium ions i.e. more cracking activity. on the other hand, increasing pressure means minimizing the formation of coke which can be due to a shorter intermediate hydrocarbon residence time inside the catalyst, and thus minimizing the coking activity. these observations are agree well with the results reported by siddiqui et al., 2011; al-hassany, 2009; gauw et al., 2002, al-khattaf et al., 1999-2002; ibrasheva et al., 2000. 0 10 20 30 40 50 60 70 80 0 2 4 6 8 10 12 14 16 c o n v e rs io n , w t. % pressure, bar zsm-22 zsm-11 hy hx fig. 10. catalytic cracking conversion vs. pressure at lhsv of 1h-1 and temperature of 723k. 4.4. catalytic cracking products distribution figures 11 to 16 show the cracking product yields were obtained over the proposed catalysts and in the temperature range of 673 to 823k while lhsv and reaction pressure were kept constant at 1h-1 and 3bar respectively. as mentioned above, six types of reactions are proposed. it can be observed that the rate of reactions increase with the increased in reaction temperature over the proposed catalysts. the difference can be further illustrated by the effect on the yield of hydrocarbons. generally, it can be observed that the selectivity towards high octane number compounds for the proposed catalysts are arranged in the following order: hy>hx>zsm-11>zsm-22 also a high yields were found for the high octane products. this many be attributed to acidity of the active sites in the catalysts and also to the effect of pore size of the catalyst. the acidity increases from zsm-22 to hy since the formation of carbenium ions favor the high acidity catalysts. these ions then will decompose to produce isomers or high octane number hydrocarbon products as mentioned above in the mechanism of cracking. these results are agree well with other observation reported by siddiqui et al., 2011; fonseca et al., 2011; graça et al., 2011, 2009; gang et al., 2008; caeiro et al., 2007; corma et al. 1995; mohan et al., 2004. al-khattaf s. and lasa h. de, et al., (1999, 2001 and 2002) have been proposed the criteria of the effect of pore size on the diffusion of hydrocarbon molecules inside hy-zeolite structure. they stayed that the critical diameter of hy-zeolite as large as 10.2å. for, iso-propylbenzene family, these molecules can diffuse and eventually crack inside the y-zeolite structure as follows: (a) if the molecule critical diameter is smaller than 7.4å (e.g. cumene) hydrocarbon molecules may evolve under kinetically controlled regime, (b) if the molecule critical diameter is larger than 7.4 å, but smaller than 10.2 å, case of 1,3-dipb and 1,3,5-tipb, with 8.4 and 9.5å critical diameters, diffusional transport may affect the overall rate of cracking. the same phenomenon has been observed by al-hassany (2009). she illustrated the diffusion of n-hexane inside hy-zeolite. she stated that the molecular diameter of hexane is 4.8å, with an increase of about 0.7å for every additional increase in branch length. ameel mohammed al-khwarizmi engineering journal, vol. 11, no. 1, p.p. 7383(2015) 80 0 5 10 15 20 25 30 650 700 750 800 850 temperature, k y ie ld , w t. % hy hx zsm-22 zsm-11 fig. 11. gaseous products yield vs. temperature at lhsv of 1h-1 and pressure of 3bar. 0 5 10 15 20 25 30 35 650 700 750 800 850 temperature, k y ie ld , w t. % hy hx zsm-22 zsm-11 fig. 12. isomeres yield vs. temperature at lhsv of 1h-1 and pressure of 3bar. 0 5 10 15 20 25 30 650 700 750 800 850 temperature, k y ie ld , w t. % hy hx zsm-22 zsm-11 fig. 13. n-paraffins yield vs. temperature at lhsv of 1h-1 and pressure of 3bar. 0 1 2 3 4 5 6 7 8 9 10 650 700 750 800 850 temperature, k y ie ld , w t. % hy hx zsm-22 zsm-11 fig. 14. cyclo-compounds yield vs. temperature at lhsv of 1h-1 and pressure of 3bar. 0 2 4 6 8 10 12 14 16 18 20 650 700 750 800 850 temperature, k y ie ld , w t. % hy hx zsm-22 zsm-11 fig. 15. olefins yield vs. temperature at lhsv of 1h-1 and pressure of 3bar. 0 1 2 3 4 5 6 7 650 700 750 800 850 temperature, k y ie ld , w t.% hy hx zsm-22 zsm-11 fig. 16. aromatics yield vs. temperature at lhsv of 1h-1 and pressure of 3bar. ameel mohammed al-khwarizmi engineering journal, vol. 11, no. 1, p.p. 7383(2015) 81 4. conclusions the transformation of ivgo was evaluated in a laboratory fixed bed reaction unit using hy, hx, zsm-11, zsm-22 zeolite catalysts. the following conclusions were drawn from the experimental results: the prepared catalysts exhibit a catalytic cracking activity within the studied range of operating conditions. the catalytic activity for the proposed catalysts arranged in the following order: hy>hx>zsm-11>zsm-22. the catalytic cracking reaction is temperature dependent, and increases with the increase in temperature. the cracking activity decreases with the increase in lhsv over the proposed catalysts. the catalytic conversion is improved by increasing operating pressure from 3 to 15 bar. the cracking product distribution dependent on the temperature and on the catalyst used. the cracking products yields increases with the increase in temperature. hy exhibit a higher octan number hydrocarbon products yields. the selectivity towards high octane number compounds for the proposed catalysts are arranged in the following order: hy>hx>zsm-11>zsm-22 acknowledgement this study was supported by a grand 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[30] thomas c. l., (1949), “the chemistry of cracking catalysts”, ind. eng. chem., vol. 41, no. 11, 2564-2573. )2015( 7383، ���� 1ا���د، �11 � ا���ارز�� ا���� �� ا�� � ا��� ���� 83 �� ذ������ ا��#�د ا��$ا#� " !�� ل ا�� ا�� + ا��% �� ا�&*�$ وا��!� ) يا�!&%�$ ا��� ز � ***0 �� و��� -��� **���� -%�/ � ن *ا��� ���� ر-�, apq 6rh9sاد/ 67mn ا?abc@6 ا?klارزdef /gh ا?abc@6 ا?<7=67897 ا;:67897***،**،* explorerxp50@yahoo.com *atuv?ا gwوuy>?;ا : mohanned12345@yahoo.com gwوuy>?;ا atuv?ا: ** kwhameed74@yahoo.com ***atuv?ا gwوuy>?;ا : ا���1� ztk[\ 6@درا ]=\? 9ز^[?ا u7e>y?ا gfاur?9ز اp?ا ]t_67`اu^?ات اa:k?ا bh c\9b?ا? ا gh9e=?ا dd[?ذات ا ]t;kt_?ا bh اعkwة أai 9ل=ry@9q ةu7v> gl و:aة ا?]^9ز usت \^qi9ت ا?k[yل . ا?z=r ا?]u7p[\ d\g?9 ھnه ا?krا9tuvylh zh وا@zsm-11( . gl ]m=ryو k@ky=)hy ،hx ،zsm-22 ا?و 6yq9r?ة اks[?ع اkw bhة وu=yeh6 وtuvylh zi9^\ . 9ربdy?ا ]tusأq ارةu[?9ت اsرa ]:اوu\ bh٦٧٣ x?و ٨٢٣إ ،b^mn kpاوح ضu\ bh٣ x?9ر، ١٥إq ا?�h 6iue ز9tدة درu: 6sارة ا?zi9^y و�h �f9byt ز9tدة ?_t[ ا?9pز t_داد y]kل ا?]^9ز ا?b7q[ ا?c89yb أن . ١-@6i9 ٣ا?x ٠.٥وueqع ulا`u\ 67او:[ : ^krm? 6t_7اzh ا?=ai9eة ا?=z>s?9q 9cv7\u\ b>=t 6halye ا�\y[gا?ان \u\�7 ا?^9r?67 . ا?^uا`67 hy> hx> zsm-11> zsm-22 أarh xmi;ت ?6veb ا?kbا\d\ zh9rm? c ا?]�kل xmi . ا?zh9r ا?=xmiai9e در6s ا?]uارة وkw xmiع u7vة kwا\c ا?a=yrt zi9^y ا?k\n a: xز�t ان ai9e=?اhy . ٍ9لi gw9ynاو df9ت ذات رvnuh btk>\ 9هd\9q zi9^y?6789 ا�ywان ا g\� : krm? 6veb?9qاzh ا?=ai9eة ا?=z>s?9q 9cv7\u\ b>=t 6halye ا hy> hx> zsm-11> zsm-22 =tkpp?9دة اt_q ا?]^9ز u7e>y?ل اk[\ b7e[\ b> . ٍ9لi لk[\ xmi لk�[?9ن ا>h�9q �w�q تucا?]^9ز أظ u7e>y?67 اm=r? 9ةn9[=?9رب اd\ ان b7e[\و .bh ا?=kاد ا�و?67 ا?6ta7m�y ا?=9dybت ا?=�arh6qkm;ت إ9ywج al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 8, no. 1, pp 65 -75 (2012) effect of fuel cetane number on multi-cylinders direct injection diesel engine performance and exhaust emissions sabah tarik ahmed miqdam tariq chaichan department of machines and equipments engineering /university of technology (received 25 april 2011; accepted 25 december 2011) abstract due to the energy crisis and the stringent environmental regulations, diesel engines are offering good hope for automotive vehicles. however, a lot of work is needed to reduce the diesel exhaust emissions and give the way for full utilization of the diesel fuel’s excellent characteristics. a kind of cetane number improver has been proposed and tested to be used with diesel fuel as ameans of reducing exhaust emissions. the addition of (2-ethylhexyl nitrate) was designed to raise fuel cetane number to three stages, 50, 52 and 55 compared to the used conventional diesel fuel whose cn was 48.5. the addition of cn improver results in the decrease brake specific fuel consumption by about 12.55%, and raise brake thermal efficiency to about 9%. simultaneously, the emission characteristics of four fuels are determined in a diesel engine. at high loads, a little penalty on co and hc emissions compared to baseline diesel fuel. nox emissions of the higher cn fuels are decreased 6%, and co of these fuels is reduced to about 30.7%. engine noise reduced with increasing cn to about 10.95%. the results indicate the potential of diesel reformation for clean combustion in diesel engines. key words: cn improver, performance, exhaust emissions, nox, ubhc,co, co2, noise. 1. introduction diesel fuel comes in several different grades, depending upon its intended use. like gasoline, diesel fuel is not a single substance, but a mixture of various petroleum-derived components, including paraffins, isoparaffins, napthenes, olefins and aromatic hydrocarbons, each with their own physical and chemical properties. diesel fuel must satisfy a wide range of engine types, differing operating conditions and duty cycles, as well as variations in fuel system technology, engine temperatures and fuel system pressures. it must also be suitable for a variety of climates. the properties of each grade of diesel fuel must be balanced to provide satisfactory performance over an extremely wide range of circumstances [1 & 2]. probably the most familiar diesel fuel property to end users and for service and repair professionals is ignition quality, as expressed by cetane number. the cetane number (cn) is a measure of the ignition quality of diesel fuel based on the ignition delay in an engine. consumers often think the cetane number is similar to the octane number for gasoline, but that is not the case. octane is a measure of a spark ignition engine fuel’s (gasoline) ability to resist engine knock. diesel cetane ratings work in the opposite direction. the higher the cetane rating, the shorter the ignition delay and the better the ignition quality . reaching desired cetane levels also limits the aromatic content of diesel fuel [3 & 4]. similar studies, (ullman, 1989 & ullman, 1990) [5 & 6] conduced that the value of the fuel cn was the key to reduce hc and co emissions. both the cn and aromatics content of the fuel affected nox emissions. nox increased as the cn is decreased and as the aromatics content is decreased. however, they showed that there is no simple answer to how the fuel properties affect emissions because different engines used in the investigation did not show similar effects. cowley, 1993 [7], also reported that the main controlling factor for emissions in diesel engines sabah tarik ahmed al-khwarizmi engineering journal, vol.8, no.1, pp 65-75 (2012) 66 is the cetane number of the fuel, although, depending on the engine type, the density of the fuel can also have some effects. similar trends have been observed by gabele, 1986 [8], when recording exhaust emissions from a diesel passenger car. the fuels tested were a “high quality” fuel (cn 46.8 and low aromatic content) and a “low quality” fuel (cn 32.0 and a high aromatic content). their results showed a decrease of up to 40% in hc, co and no, when using the “high quality” diesel fuel [9]. shell and mercedes-benz companies have joined efforts to investigate the effects of diesel fuel properties (density, distillation range, cetane number and aeronautics content) on exhaust emissions in an advanced european indirect injection (101) passenger car and a modem commercial vehicle direct injection (di) engine [10]. their results indicated that the cn and not the total aromatics content accounted for the variation in nox emissions. by increasing the cn, the nox emissions were reduced, particularly when raising cn from levels of 45 to 55. above cn 55 the reductions became rather small [11 & 12]. contradicting results were found by rantanen, 1993 [13]. emissions were measured from four turbocharged direct injection engines chosen as representative types of existing heavy duty engines. the cetane number was found not to be important in reducing nox emissions [14 &15]. this work represents a part of a continuing research efforts carried out over years at the machines & equipments engineering deprt. university of technology to provide improved knowledge of the combustion phenomena in fuels of internal combustion engines in general and the diesel engines in particular. the focus in this article is on investigating the effects of improveng cetane number of diesel fuel, on the performance and emission characteristics of multi cylinder direct injection diesel engine under variable operating conditions. 2. experimental setup experimental apparatus of engine under study is direct injection (di), water cooled four cylinders, in-line, natural aspirated fiat diesel engine (fig. 1), whose major specifications are shown in table 1. the engine was coupled to a hydraulic dynamometer through which load was applied by increasing the torque. this dynamometer was calibrated at the central organization for measurments and quality control-baghdad. fig. 1. photo of the test internal combustion engine. table 1, tested engine specifications . engine type 4cyl., 4-stroke engine model td 313 diesel engine reg combustion type di, water cooled, natural aspirated displacement 3.666 l valve per cylinder two bore 100 mm stroke 110 mm compression ratio 17 fuel injection pump unit pump 26 mm diameter plunger fuel injection nozzle hole nozzle 10 nozzle holes nozzle hole dia. (0.48mm) spray angle= 160o nozzle opening pressure=40mpa the multigas model 4880 emissions analyzer was used to measure the concentration of nitrogen oxide (nox), unburned total hydrocarbon ubhc, co2 and co. the analyzer detects the co, co2, hc, nox, and o2 content. the gases are picked up from the engine exhaust pipe by means of a probe. they are separated from water they contain through a condensate separating filter, and then they are conveyed in the measuring cell. a ray of sabah tarik ahmed al-khwarizmi engineering journal, vol.8, no.1, pp 65-75 (2012) 67 infrared light (which is generated by the transmitter) is send through optical filters on to the measured elements. the gases which are contained in the measuring cell absorb the ray of light in different wave lengths; according to their concentration. the h2, n2 and o2 gases due to their molecular composition (they have the same number of atoms), do not absorb the emitted rays. this prevents from measuring their concentration through the infrared system. the co, co2, nox and hc gases, because of their molecular composition, absorb the infrared rays at specific wavelengths (absorption spectrum). this analyzer was calibrated at the ministry of environment iraq. overall sound pressure was measured by precision sound pressure level meter supplied with microphone type 4615, as shown in fig. 2; the devise was calibrated by standard calibrator type pisto phone 4220. fig. 2. overall sound pressure used in tests. four kinds of diesel fuel with different cetane numbers were selected for the study. the conventional iraqi diesel fuel (cn=48.5) was taken as baseline diesel. a common cetane improving additive, 2-ethylhexyl nitrate (also known as iso-octyl nitrate) is used to improve diesel fuel ignitability in small concentrations. it is commonly produced by several different manufacturers; the exact product used in these tests was manufactured under the name hitec 4103. the more formal chemical formula is c8h17no3, with the basic structure an ethyl hexane molecule with one of the hydrogen atoms replaced with an no3 nitrate radical. it was used to raise cetane number in three different rates (cn=50, 52 &55). fuel properties and the constitutions for the four fuels were measued at al-najaf refinary laboratory. these properties are recorded in table 2. table 2, properties of cetane numbers for the four tested fuels. properties fuel 1 (low cn) fuel 2 (medium cn) fuel 3 (high cn) fuel 4 (ultra high cn) cetane number 48.5 50 52 55 density (g/ml) 0.838 0.846 0.853 0.856 lower heating value (mj/kg) 42.36 42.87 42.44 43.18 h:c ratio 1.8 1.87 1.88 1.99 alkalines (%) 72 80 89 96 olifines (%) 2 1 2 2 aromatics (%) 26 19 17 2 the following equations were used in calculating engine performance parameters [16]: 1brake power 𝑏𝑝 = 2𝜋∗𝑁∗𝑇 60∗1000 𝑘𝑊 …(1) 2brake mean effective pressure 𝑏𝑚𝑒𝑝 = 𝑏𝑝 × 2∗60 𝑉𝑠𝑛 ∗𝑁 𝑘𝑁/𝑚2 … (2) 3fuel mass flow rate 𝑚 𝑓 = 𝑣𝑓×10−6 1000 × 𝜌𝑓 𝑡𝑖𝑚𝑒 𝑘𝑔 𝑠𝑒𝑐 … (3) 4air mass flow rate 𝑚 𝑎 ,𝑎𝑐𝑡 . = 12 𝑕𝑜∗0.85 3600 × 𝜌𝑎𝑖𝑟 𝑘𝑔 𝑠𝑒𝑐 … (4) 𝑚 𝑎𝑡𝑕𝑒𝑜 . = 𝑉𝑠.𝑛 × 𝑁 60∗2 × 𝜌𝑎𝑖𝑟 𝑘𝑔 𝑠𝑒𝑐 … (5) 5brake specific fuel consumpotion 𝑏𝑠𝑓𝑐 = 𝑚 𝑓 𝑏𝑝 × 3600 𝑘𝑔 𝑘𝑊 .𝑕𝑟 … (6) sabah tarik ahmed al-khwarizmi engineering journal, vol.8, no.1, pp 65-75 (2012) 68 6total fuel heat 𝑄𝑡 = 𝑚 𝑓 × 𝐿𝐶𝑉 𝑘𝑊 7brake thermal efficiency 𝜂𝑏𝑡𝑕 . = 𝑏𝑝 𝑄𝑡 × 100 % …. (7) the fuel properties show that the conventional diesel fuel has low cetane number, compared to the other improved diesel fuels. in the experiment, the above four fuel blends with different cetane numbers proportions were operated on the engine, meanwhile combustion characteristics were measured and analyzed at the same brake mean effective pressure (bmep), and these parameters were compared with those of pure diesel combustion in order to clarify the effect of cetane number on engine performance and emissions. before testing any other diesel fuel with a different cn, the fuel lines were purged and the fuel filters were changed. the fuel supply line was later connected to the tank and the next diesel to be tested was fueled to the system. the engine was then run for a sufficient period of time in order to ensure that the last amount of the previously used fuel which could possibly still remain in the system was consumed. experimental errors and uncertainties the difference between measured and true values of quantity is known as an error. by assigning a value of that error, an uncertinity is defined. the uncertinities in each individual measurment lead to uncertainities in experiment [17]. in general, the uncertainty in the results is: 𝑒𝑅 = 𝜕𝑅 𝜕𝑉1 𝑒1 2 + 𝜕𝑅 𝜕𝑉2 𝑒2 2 + ⋯+ 𝜕𝑅 𝜕𝑉𝑛 𝑒𝑛 2 0.5 …. (8) where: 𝑒𝑅 : uncertainty in the results r : a given function of the independent variables v1, v2, …, vn or r=r(v1, v2, …, vn). ei : uncertainty interval in the nth variable. the partial derivative 𝜕𝑅 𝜕𝑉1 is a measure of the sensitvity of the result to a single variable. the summarized analysis of the experimental accuracy of the measuring properties for some selected measuring devices is shown in table (3). from these values the experiments uncertainties can be calculated: 𝑒𝑅 = 0.045 2 + 0.07 2 + 0.95 2 + 0.98 2 + 1.24 2 + 0.7 2 + 0.022 2 0.5 = ∓1.974 …(9) table 3 experimental accuracies. measurements accuracies in this study temperatures 0.045 air flow 0.07 fuel flow 0.95 engine speed 0.98 engine tourque 1.24 sound presure level 0.7 emitted exhaust gases concentrations 0.022 3. results and discussion cetane number requirements of an engine will vary depending on engine size, speed and load variations, starting conditions and atmospheric conditions. since a diesel engine ignites the fuel without a spark, proper cetane levels are very important. the air/fuel mixture is ignited by the combination of compression and heating of the air due to compression. the fuel injected into the cylinder at the precise time ignition is desired to optimize performance, economy and emissions. fig. 3 represents the effect of cn on brake specific fuel consumption (bsfc) for the four tested fuels. increasing fuel cn reduces bsfc, although it is still high at low loads. increasing fuel’s cn improves combustion and raises combustion chamber temperatures. increasing combustion chamber temperatures gives low fuel delay period, and gives better ignition. reducing the load reduces temperatures inside combustion chamber, and increases fuel delay period, resulting in bad combustion that needs more fuel to compensate the lost power. sabah tarik ahmed al-khwarizmi engineering journal, vol.8, no.1, pp 65-75 (2012) 69 fig. 3. cn effect on bsfc for variable loads . increasing cn improved brake thermal efficiency, as fig. 4 represents. brake thermal efficiency is a criterion of the useful used thermal power produced from fuel burning. burning improvements cuases higher brake thermal efficiency. cn indicates the ability of fuel for self ignition, its inceaments reduce delay period and lead to better combustion. so increasing cn in this paper from 48.5 to 55 increased brake thermal efficiency by 9% and reduced bsfc by 12.55%. fig. 4. cn effect on brake thermal efficiency for variable loads. exhaust gas temperatures are increased by increasing load, while increasing cn reduces these temperatures, as shown in fig. 5. increasing load needs more fuel to be burned which rises exhaust temperatures. on the other hand, increasing cn improves delay period, making the burning process to be completed at top dead center, giving chance to expand exhaust gases to give maximum power to piston, and to be cooled at power stroke. increasing cn (from baseline cn=48.5) gave reduction in exhaust temperatures by 1.2, 6.1 and 9.3% for cn 50, 52 and 55 respectively. fig. 5. cn effect on exhaust gas temperatures for variable loads. brake power (bp) increased with increasing engine speed, as fig. 6 illustrates. increasing cn increases bp also. brake power increased by 1.1, 3.88 and 5.6% for cn 50, 52 and 55 respectively compared with baseline diesel fuel (cn=48.5). cn increment reduces bsfc for all engine speed range, as fig. 7 represents. increasing cn increases burning efficiency giving more power with less fuel, and these improvements grow with increasing cn. reductions in bsfc were 2.7, 3.9 and 5.5% for cn 50, 52 and 55 compared with baseline diesel (cn= 48.5). fig. 6. cn effect on brake power for variable engine speeds. 0.14 0.16 0.18 0.2 0.22 0.24 0.26 0 20 40 60 80 100 b sf c ( k g /k w h ) bmep (kn/m2) n=1500 rpm, cr=17:1, it=38°btdc diesel (cn= 48.5) diesel (cn= 50) diesel (cn= 52) diesel (cn= 55) 100 150 200 250 300 350 400 450 500 0 20 40 60 80 100 e x h a u st g a s te m p e r a tu r e s (° c ) bmep (kn/m2) n=1500 rpm, cr=17:1, it=38° btdc diesel (cn= 48.5) diesel (cn= 50) diesel (cn= 52) diesel (cn= 55) 24 25 26 27 28 29 30 1000 1500 2000 2500 3000 b r a k e p o w e r ( k w ) engine speed (rpm) cr=17:1, it=38° btdc, 44 kn/m2 diesel (cn= 48.5) diesel (cn= 50) diesel (cn= 52) diesel (cn= 55) 24 25 26 27 28 29 30 31 32 33 34 0 20 40 60 80 100 b r a k e t h e r m a l e ff ii c ie n c y ( % ) bmep (kn/m2) n=1500 rpm, cr=17:1, it=38° btdc diesel (cn= 48.5) diesel (cn= 50) diesel (cn= 52) diesel (cn= 55) sabah tarik ahmed al-khwarizmi engineering journal, vol.8, no.1, pp 65-75 (2012) 70 fig. 7. cn effect on bsfc for variable engine speeds. raising cn reduces exhaust gas temperatures for all engine speed range, as fig. 8 indicates. raising fuel cn improves burning efficiency, in turn raising indicated thermal efficiency and reducing bsfc, so these improvements reflect on exhaust temperatures. the reductions were 2.4, 5.94 and 9.24% for cn 50, 52 and 55 respectively compared with baseline diesel. given the operating conditions, it is easy to see why cetane level is important. in addition to improving fuel combustion, increasing cetane level also tends to reduce emissions of nitrogen oxides (nox). these emissions tend to be more pronounced when working with lower cetane number fuels as fig. 9 shows. the decrease in cn caused an increase in no, because of the long ignition delay. fig. 8. cn effect on exhaust gas temperatures for variable engine speeds. fig. 9. cn effect on nox concentrations for variable loads. fig.10 shows the variation of the co concentration in exhaust gas with variable engine loads, when the engine was operated on commercial diesel fuel of 48.5 cn, and modified fuel of 50, 52 and 55 cn diesel fuels. carbon monoxide is the primary intermediate product in the hydrocarbon oxidation. the presence of co in lean fuelair mixtures exhaust is an indication that some of the co produced through the oxidation reactions could not be oxidized further to carbon dioxide. with very lean engine operation and small load within the partial motoring region, the co concentrations recorded imply that they also partially originate from the incomplete combustion. these emissions are reduced with increasing cn in the fuel by 11.79, 31.2 and 56.34 for cn 50, 52 and 55 respectively compared with baseline diesel fuel (cn=48.5). fig. 10. cn effect on co concentrations for variable loads. 0.025 0.05 0.075 0.1 0.125 0.15 0.175 0.2 0 20 40 60 80 100 c o c o n c e n tr a ti o n s (% v o l. ) bmep (kn/m2) n=1500 rpm, cr=17:1, it=38btdc diesel (cn= 48.5) diesel (cn= 50) diesel (cn= 52) diesel (cn= 55) 0.14 0.16 0.18 0.2 0.22 0.24 0.26 1000 1500 2000 2500 3000 b sf c ( k g /k w h ) engine speed (rpm) cr=17:1, it= 38° btdc, 44 kn/m2 diesel (cn= 48.5) diesel (cn= 50) diesel (cn= 52) diesel (cn= 55) 300 350 400 450 500 550 600 1000 1500 2000 2500 3000 e x h a u st g a s te m p e r a tu r e s (° c ) engine speed (rpm) cr=17:1, it= 38° btdc, 44 kn/m2 diesel (cn=48.5) diesel (cn=50) diesel (cn=52) diesel (cn=55) 0 100 200 300 400 500 600 700 800 0 50 100 n o x c o n c e n tr a ti o n s (p p m ) bmep (kn/m2) n=1500 rpm, cr=17:1, it=38btdc diesel (cn= 48.5) diesel (cn= 50) diesel (cn= 52) diesel (cn= 55) sabah tarik ahmed al-khwarizmi engineering journal, vol.8, no.1, pp 65-75 (2012) 71 the variations of un-burnt hydrocarbons (ubhc) concentration in the exhaust gases have a very similar trend to that observed for the co concentrations, as fig 11 indicates. the figure shows that at low loads a considerable fraction of the hydrocarbons representing significant quantities of fuel can pass through the engine cylinder partially burned or un-reacted. when the engine runs at very light loads, the poor atomization of the diesel fuel with increased ignition delay, large cyclic variations and low charge temperature, result in a very low gaseous fuel utilization. fig. 11. cn effect on ubhc concentrations for variable loads. at higher loads, when the diesel concentration in the cylinder charge is high enough, the ubhc tend to reduce. diesel fuel with cn= 55 improved the utilization of the fuel up to 20% compared with baseline diesel. also, it reduced the ubhc concentration in the exhaust, as compared to the 48.5 cn fuel. the cn 50 fuel had a slightly adverse effect. little differences were found at very light loads, as well as at full load. co2 concentrations increased with increasing cn from 48.5 to 55, as fig. 12 represents. the co2 increments were due to reduction in co and ubhc concentrations, which oxided totally demonstrated better burning. engine noise reduced due to increasing cn, as shown fig. 13. burning improvements gave smooth movements for dynamic parts, and reduces vibration which reflects on reducing engine noise, while increasing load acts in opposite of cn effect and increases noise. from the figure it is apparent that the measured sound level is the summation of these two effects. the reductions were 3.9, 7 and 11.67% for cn 50, 52 and 55 respectively compared with baseline diesel. fig. 12. cn effect on co2 concentrations for variable loads. fig. 13. cn effect on sound level for variable loads. the cetane number of a diesel fuel is a measure of its readiness to ignite. fuels with higher cetane numbers will burn more efficiently, by releasing lower levels of emissions and give better fuel economy than fuels with lower cetane numbers as well as lesser emissions as fig. 14 reveals, nox concentrations are reduced with increasing cn, and it is reduced also with increasing engine speed. increasing engine speed increases turbulence inside combustion chamber, and reduces the available time for nox formation. similarly, increasing cn improves burning by reducing delay period, resulting in a complete burning which consumes all oxygen in the chamber, as a result reducing nox concentrations. these concentrations are reduced by 2.1, 2.9 and 6% for cn 50, 52 and 55 0 10 20 30 40 50 60 70 80 0 20 40 60 80 100 h c c o n c e n tr a ti o n s (p p m ) bmep (kn/m2) n=1500 rpm, cr=17:1, it=38° btdc diesel (cn= 48.5) diesel (cn= 50) diesel (cn= 52) diesel (cn= 55) 0 2 4 6 8 10 12 14 0 20 40 60 80 100 c o 2 c o n c e n tr a ti o n s (% v o l. ) bmep (kn/m2) n=1500 rpm, cr=17:1, it=38° btdc diesel (cn= 48.5) diesel (cn= 50) diesel (cn= 52) diesel (cn= 55) 70 75 80 85 90 95 100 0 20 40 60 80 100 s o u n d ( d b ) bmep (kn/m2) n=1500 rpm, cr=17:1, it=38° btdc diesel (cn= 48.5) diesel (cn= 50) diesel (cn= 52) diesel (cn= 55) sabah tarik ahmed al-khwarizmi engineering journal, vol.8, no.1, pp 65-75 (2012) 72 respectively. it can be supposed that these reductions are not enough to reduce nox to the wanted limits without using other techniques, like exhaust gas recirculation (egr). fig. 14. cn effect on nox concentrations for variable engine speeds . ubhc concentrations are reduced with increasing engine speeds from 1000 rpm to 2250, after this speed these concentration start to increase, as fig 15 shows. increasing cn impact is reducing ubhc emissions due to improvements in fuel combustion and burning. while increasing engine speed from medium to high speed increases the air fuel mixture turbulence, pushing some fuel to the piston crevice where its burning will be difficult, and it will appear as ubhc. fig. 15. cn effect on ubhc concentrations for variable engine speeds . co concentrations behave as ubhc, as fig. 16 represents. for the same reasons of ubhc reduction and increment, co concentrations are reduced by 5.67, 15.5 and 30.7% for cn 50, 52 and 55 compared to baseline diesel. increasing cn has large effect in reducing co and ubhc; it also has some effect on nox concentration reduction. fig. 16. cn effect on co concentrations for variable engine speeds. co2 concentrations are increased with increasing engine speed as fig. 17 illustrates. it also increases with increasing cn. increasing engine speed needs more fuel to be burnt; as a result higher co2 concentrations will be exhausted. increasing cn will improve burning and reduce ubhc and co concentrations, which reflect on increasing co2 concentrations. fig. 17. cn effect on co2 concentrations for variable engine speeds. engine noise rises at low speed and reduces at high speed, as fig. 18 shows. it is also reduced with increasing cn. one of the main factors that are known to affect the combustion noise is the 200 220 240 260 280 300 320 340 360 380 400 1000 1500 2000 2500 3000 n o x c o n c e n tr a ti o n s (p p m ) engine speed (rpm) cr=17:1, it= 38° btdc, 44 kn/m2 diesel (cn= 48.5) diesel (cn= 50) diesel (cn= 52) diesel (cn= 55) 15 20 25 30 35 40 1000 1500 2000 2500 3000 h c c o n c e n tr a ti o n s (p p m ) engine speed (rpm) cr=17:1, it= 38°btdc, 44 kn/m2 diesel (cn= 48.5) diesel (cn= 50) diesel (cn= 52) diesel (cn= 55) 0.025 0.035 0.045 0.055 0.065 0.075 0.085 1000 1500 2000 2500 3000 c o c o n te n t (% v o l. ) engine speed (rpm) cr=17:1, it= 38° btdc, 44 kn/m2 diesel (cn= 48.5) diesel (cn= 50) diesel (cn= 52) diesel (cn= 55) 0 2 4 6 8 10 12 14 1000 1500 2000 2500 3000 c o 2 c o n c e n ta r ti o n ( v o l% ) engine speed (rpm) cr=17:1, it=38º btdc, 44 kn/m2 diesel (cn= 48.5) diesel (cn= 50) diesel (cn= 52) diesel (cn= 55) sabah tarik ahmed al-khwarizmi engineering journal, vol.8, no.1, pp 65-75 (2012) 73 pressure rise rate during combustion. it has also been proven that the maximum rate of pressure rise is directly proportional to the sound pressure level (spl) in decibels observed in the main chamber of a diesel engine. however, this work proved that increasing cn reduces engine noise by 1.95, 7.8 and 10.95 for cn 50, 52 and 55 respectively compared to baseline diesel fuel. fig. 18. cn effect on sound level for variable engine speeds. 4. conclusions the effects of cn improver on performance, gas emissions and combustion characteristics of a four cylinders, direct injection compression ignition engine fuelled with several diesel fuels containing various proportions of cn improver have been investigated, and compared to iraqi conventional diesel fuel (baseline fuel with cn=48.5). the main conclusions obtained are as follows: 1. fuel cetane number strongly affects the ignition delay and combustion phasing of this single-injection premixed diesel combustion mode. increasing cetane number results in a shorter ignition delay, which for a given injection timing results in earlier combustion phasing. 2. the bsfc reduced compared to the baseline diesel. the maximum reduction reached (at constant speed and variable engine loads) was for diesel fuel with cn=55. the reduction was 12.55% compared with baseline diesel fuel. while at constant load and variable engine speed the reduction reached was 5.5% for diesel fuel with cn=55. 3. the brake thermal efficiency improved remarkably with increasing cn. the maximum increament attained was 9% for diesel fuel with cn=55 compared with baseline fuel. 4. increasing fuels cetane numbers reduces exhaust gas temperatures. the maximum reduction obtained was 9.24% for diesel fuel with cn=55 compared with baseline diesel (cn=48.5). 5. brake power increased with increasing fuel cetane number. the maximum increament achieved was 5.6% for diesel fuel with cn=55 compared with baseline fuel. 6. nox emissions decreased simultaneously when diesel engine fueled with higher cn diesel fuels. the maximum reduction attained was 6% for diesel fuel with cn=55 compared with baseline fuel. 7. co emission decreased with the increase of cn rating. the maximum reduction attained was 30.7% for diesel fuel with cn=55 compared with baseline fuel. 8. hc emission reduced by increasing cn rating of the fuel. 9. engine noise reduced remarkably with increasing cn. 10. co2 emissions increased with increasing fuel cn. 11. the impacts of cn on emissions vary with engine operating conditions. at high load conditions, it has stronger effects on emissions. while at low loads, it has slight effects on emission reduction. with the increasing cn, nox emissions decrease a little, while co emissions and unburned hc emissions decrease at most operating conditions. all the results indicate the potential of cn for clean combustion in diesel engines. 12. the study demonstrates that limited increaments in cn (from cn=48.5 to cn=50) gives insignificant improvement of engine performance and exhaust emissions. notation it injection timing cn cetane number di direct injection n engine speed (rpm) t engine tourqe vsn swept volume °btdc degree before top dead centre bmep brake mean effictive pressure bte brake thermal efficiency 70 75 80 85 90 95 100 1000 1500 2000 2500 3000 s o u n d ( d b ) engine speed (rpm) cr=17:1, it=38ºbtdc, , 44 kn/m2 diesel (cn= 48.5) diesel (cn= 50) diesel (cn= 52) diesel (cn= 55) sabah tarik ahmed al-khwarizmi engineering journal, vol.8, no.1, pp 65-75 (2012) 74 ca crank angle cr compression ratio ubhc unburnt hydrocarbon co carbon monoxide co2 carbon dioxide nox nitrogen oxides db decibel lcv lower calorific value 5. referances [1] quingley et al, 2009. a review of fuel and additive performance in the new cec f-9808 dw10 injector fouling test, fuels colloquim esslingen. [2] gunea c d. 1997. examination of the effects of pilot fuel quality on the performance of gas fueled diesel engines, msc.thesis, the university of calgary, calgary, alberta. [3] icingür y, altiparmak d, 2003. effect of fuel cetane number and injection pressure on a di diesel engine performance and emissions, energy conv. mngm., vol. 44, no. 3, pp: 389–397. [4] egúsquiza j c, braga s l and braga c v m, 2009. performance and gaseous emissions characteristics of a natural gas/diesel dual fuel turbocharged and after cooled engine, j. of the braz. soc. of mech. sci. & eng, vol. xxxi, no. 2, april-june. [5] ullman tl, 1989. investigation of the effects of fuel composition on heavy duty diesel engine emissions, sae paper no. 892072. [6] ullman t l, mason r l and montalvo d a, 1990. effects of fuel aromatics, cetane number and cetane improver on emissions from a 1991 prototype heavy duty diesel engine, sae paper no. 9021 71. [7] cowley l t, lejeune a and lange w w, 1993. the effects of fuel composition including aromatic content on exhaust emissions from a range of heavy duty diesel engine, inst. mech. eng., 2nd seminar on "worldwide engine emission standards and how to meet them, london, may. [8] gabele p, karches w, ray w and perry n, 1986. emissions from a light-duty diesel: ambient temperature and fuel effect, sae trans. 860618, vo1.95, sect.6. [9] obodeh o and ajuwa c i, 2009. evaluation of artificial neural network performance in predicting diesel engine nox emissions, research journal of applied sciences, engineering and technology, vol. 33, no. 4, pp: 642-653. [10] lange w w, shafer a, lejeune a, naber o, reglitzky a a and gairing m, 1993. the influence of fuel properties on exhaust emissions from advanced mercedes benz diesel engines", sae trans. 932685, vol. 102, sect. 3. [11] zannis t c, hountalas d t, papagiannakis r g, and levendis y a, 2008. effect of fuel chemical structure and properties on diesel engine performance and pollutant emissions: review of the results of four european research programs, paper no. 2008-01-0838. [12] máté z, 2009. potential future renewable fuel challenges for internal combustion engine, járművek és mobilgépek, vol. ii, no. iv, pp: 397-403. [13] rantanen l, mikkonen s, nylund l, kochiba p, lappi m and nylund n o, 1993. effect of fuel on the regulated, unregulated and mutagenic emissions of di diesel engines, sae trans. 932686, vol. 102, sect. 4. [14] bamgboyel a i and hansen a c, 2008. prediction of cetane number of biodiesel fuel from the fatty acid methyl ester (fame) composition, int. agrophysics, vol. 22, pp: 21-29. [15] jehad a, yamin a, eyad s and abu-nameh m, 2007. environmental assessment of a diesel engine under variable stroke length and constant compression ratio, american journal of applied sciences, vol. 4, no. 5, pp: 257-263. [16] keating e l, applied combustion, 2nd eddition, taylor & francis group, llc, 2007. [17] ashrea giude line. guide engineering analysis of experimental data, guideline 2-1986. (2012 )75 65، صفحة 1، العذد 8 هجلة الخىارزهً الهٌذسٍة الوجلذ احوذ صباح طارق 75 هتعذد األسطىاًاتهحرك دٌسل العادم لتأثٍر الرقن السٍتاًً للىقىد على أداء وهلىثات ري حقي هباشر صباح طارق أحوذ هقذام طارق جٍجاى انجبيؼخ انزكُٕنٕجٍخ / قغى ُْذعخ انًكبئٍ ٔانًؼذاد الخالصة ثغجت أصيخ انطبقخ ٔيحذداد انزهٕس انجٍئً انًزشذدح، رقذو يحشكبد انذٌضل أيم جٍذ نًحشكبد انًشكجبد، ٔثكم األحٕال يطهٕة انكثٍش يٍ انؼًم نزقهٍم .يهٕثبد انؼبدو نًحشك انذٌضل، ٔاػطبء فشصخ نالعزخذاو األيثم نًٕاصفبد احزشاق ٔقٕد انذٌضل نهؼًم ػهى سفغ (ْكغٍمثبًَ ٍَزشاد اثٍم)رى اعزخذو َٕع يٍ إَٔاع يحغُبد انشقى انغٍزبًَ يغ ٔقٕد دٌضل نزقهٍم يهٕثبد انؼبدو، ٔقذ رًذ إضبفخ إٌ إضبفخ يحغٍ انشقى انغٍزبًَ َزج . 48.5 يقبسَخ يغ انٕقٕد انزجبسي انًغزخذو يحهٍب راد انشقى انغٍزبًَ 55، ٔ 52 ،50انشقى انغٍزبًَ نثالس يشاحم ًْ .%9، ٔسفغ نهكفبءح انحشاسٌخ انًكجحٍخ ثحذٔد %12.5 ثحذٔد ػُّ رقهٍم نالعزٓالك انُٕػً انًكجحً نهٕقٕد ػُذ أحًبل يشرفؼخ يقبسَخ نٕقٕد انذٌضل coٔ ubhc كًب رى قٍبط انًهٕثبد انُبرجخ ألَٕاع انٕقٕد األسثؼخ فً َفظ انٕقذ، ٔقذ نٕحع اسرفبع رشاكٍض ٔاَخفض %. 30.7 ثحذٔدco، كًب قهذ نٓزِ انًجًٕػخ رشاكٍض %6 قهٍال ألَٕاع انٕقٕد راد انشقى انغٍزبًَ األػهى ثحذٔد noxاألعبعً، ٔقهذ رشاكٍض ثضٌبدح انشقى انغٍزبًَ نهٕقٕد، أظٓشد انُزبئج انحبجخ إنى رحغٍٍ َٕػٍخ ٔقٕد انذٌضل انًُزج نهٕصٕل إنى يحشكبد دٌضل % 10.95ضجٍج انًحشك ثحذٔد .راد احزشاق َظٍف buckling analysis of unidirectional polymer matrix composite plates dr. jawad kadhim uleiwi /al-khwarizmi engineering journal ,vol.2, no. 2 pp 42-55 (2006) 42 buckling analysis of unidirectional polymer matrix composite plates dr. jawad kadhim uleiwi material engineering. dept. / university of technology (received 14 november 2005; accepted 4 april 2006) abstract: this study deals with the estimation of critical load of unidirectional polymer matrix composite plates by using experimental and finite element techniques at different fiber angles and fiber volume fraction of the composite plate. buckling analysis illustrated that the critical load decreases in nonlinear relationship with the increase of the fiber angle and that it increases with the increase of the fiber volume fraction. the results show that the maximum value of the critical load is (629.54 n/m) at ( = 0) and (vf = 40 %) for the finite element method, while the minimum value of the critical load is (49 n/m) at ( = 90) and (vf = 10 %) for the experimental results. the results also indicated that the maximum difference between the finite element analysis and experimental work is about (11 % ) at (  = 0) and (vf = 40 %). 1.introduction many aeroengine components consist of thin-walled plates under loads which can potentially cause failure by buckling. these loads comprise combinations of compressive, shear and bending force [1]. the word "buckling" evokes an image of failure of structures which has been compressed in some way. pictures and perhaps sound come to mind of sudden, catastrophic collapse involving very large deformations [2]. when the magnitude of the load on a structure is such that the equilibrium is changed from stable to unstable the load is called a critical load ( or buckling load ) [3]. the nature of the buckle pattern in plate depends not only upon the type of the applied loading but also upon the manner in which the edges are supported, shape (dimension) of the problem and material properties. the composite plate used in this study was a unidirectional polymer matrix composite plate made from glass fiber – epoxy matrix composite with constant length to width ratio (l/w = 2) at different fiber angles and fiber volume fraction. the aim of this work is to investigate the buckling analysis of the al-khwarizmi engineering journal al-khwarizmi engineering journal, vol.2,no.2,pp 42-55 (2006) dr. jawad kadhim uleiwi /al-khwarizmi engineering journal ,vol.2, no. 2 pp 42-55 (2006) 43 composite plate by using the finite element analysis and the experimental work. an enormous amount of effort has been exerted on the subject of buckling since the beginning of the 20th century mainly the work performed by naca (national advisory committee for aeronautics). rais-rohani, m and marcellier, p. [4,5] studied the effects of elastic edge conditions, aspect ratio, and face sheet ply pattern on the buckling loads and natural frequencies of anisotropic rectangular sandwich plates by using rayleigh – ritz method. timothy l.c. chen and charles w. bert [6] used the theory for buckling of laminated, anisotropic, thin plates to study buckling of the rectangular plates, laminated of composite material and subject to uniaxial compressive loading for optimal design plates laminated of glass/epoxy, boron/epoxy, and carbon/epoxy composite materials. hyonny kim and keith t. kedward [7] studied the global buckling and local sublaminate buckling of the laminated plate containing zone of delamination by using rayleigh – ritz method and finite element models. timoshenko, stephen p. and james m. gere [8] explained the approximate method to obtain the results of buckling stresses which are always higher than the exact solution. yasui [9] presented what appears to be the first in-depth parametric study of buckling behavior of laminated composite plates with a central circular cutout that has been obtained by using the finite element method. rouse [10] presented an experimental investigation of the buckling and postbuckling behavior of square graphite-epoxy and graphitethermoplastic plates loaded in shear. 2.theoretical analysis using lamination theory, the strains in structural laminate resulting from a given applied stress from information on the basic lamina which are: glass and epoxy moduli, poisson's ratios, densities, and volume fractions of fibers, in addition to geometric data for the composite plate. the constitute relations may be established for a lamina by assuming that the lamina is a homogeneous orthotropic material in a state of plane stress. the geometry of a single filamentary lamina is shown in figure (1) [11]. hook's law for a composite material with orthotropic properties in a plane stress state is:                                 12 2 1 33 2221 1211 12 2 1 00 0 0       q qq qq (1) the components of the reduced stiffness matrix, [q]. are:  21121111 1/  eq (2)  211211212112 1/   eqq (3) 1233 gq  (4) and the longitudinal and lateral elastic modulus is predicted by the rule of mixtures formula. mmff vevee 1 (5) fmmf mf veve ee e   2 (6) and the major poisson's ratio is given by: mmff vv  12 (7) and the minor poisson's ratio 21 can be estimated from 1 2 1221 e e   (8) dr. jawad kadhim uleiwi /al-khwarizmi engineering journal ,vol.2, no. 2 pp 42-55 (2006) 44 for a given fiber angle ( ) the stress/strain relationship                                 xy y x xy y x qqq qqq qqq       333231 232221 131211 (9)     4 22 22 3312 4 1111 sincossin 22cos   q qqqq     4 22 22 3312 4 1122 coscossin 22sin   q qqqq     44 12 22 3322112112 cossincossin 4   q qqqqq   )cos(sincossin 22 44 33 22 3312221133    q qqqqq       cossin2cos sin2 3 332212 3 3312113113   qqq qqqqq       3 332212 3 3312113223 cossin2cos sin2   qqq qqqqq also the stress/strain equation in the ply can be written in reference to the geometric midplane as follows:                                                        xy y x xy y x xy y x k k k qqq qqq qqq z qqq qqq qqq 333231 232221 131211 333231 232221 131211          (10) to find the force resultants acting on the total laminate, equation (10) is integrated over the total thickness in the z direction.                                        n k z z xy y x k t t xy y x xy y x dzdz n n n k k 1 2/ 2/ 1       (11)                                        n k z z xy y x k t t xy y x xy y x dzzdzz m m m k k 1 2/ 2/ 1       (12) after integration and rearranging equations (11 and 12 ), the constitutive equations can be obtained as follows:                                                                     xy y x xy y x xy y x xy y x k k k dddbbb dddbbb dddbbb bbbaaa bbbaaa bbbaaa m m m n n n       333231333231 232221232221 131211131211 333231333231 232221232221 131211131211 (13) where:        n k kkijij zzqa 1 1        n k kkijij zzqb 1 2 1 2 2 1        n k kkijij zzqd 1 3 1 3 3 1 3.experimental work the experimental part was carried out in the field to determine experimentally the critical load on many specimens of the composite material of unidirectional glass fiber – epoxy matrix composite plates with different fiber angles and volume fraction of fiber as following: vf = 10 %, 20%, 30% and 40%  = 0, 15, 30, 45, 60, 75, 90 the dimension of the test specimen has a length of (200 mm) and width of (100 mm) and a thickness of (1mm). figure (2) represents the test machine with a test specimen of the dr. jawad kadhim uleiwi /al-khwarizmi engineering journal ,vol.2, no. 2 pp 42-55 (2006) 45 composite plate with some accessories like dial-gauge and load indicator to measure the lateral deflection of the composite plate. 4.finite element analysis the finite element analysis carried out as part of this work was performed using the ansys package in the buckling analysis of composite plate to determine the critical load at which the structure becomes unstable. element selected this element is used to modal the composite plate. the element has six degrees of freedom at each node translation in the x,y and z directions and rotations about the nodal x,y and z-axes. the geometry, node locations, and the coordinate system for this element are shown in figure (3). the element is defined by eight nodes four thicknesses and orthotropic material properties [12]. 5.boundary conditions and mesh generation there are two main types of boundary condition (displacement and load boundary condition). the composite plate is a simply – supported plate from the two opposite edge and free from other edges and the load is applied axially on the two opposite edges. as for the mesh generation of the composite plate, it is necessary to discretize it into a sufficient number of elements in order to obtain a reasonable accuracy. figure (4) represents the mesh generation and boundary conditions of the composite plate. 6.results and discussions the results obtained from the experimental work and the finite element analyses of the buckling analysis of the composite plate are discussed here. figure (5) shows the lateral deflection contours and the value of the critical load of the unidirectional composite plate at (vf = 10 % ) it is clear from these figures that the buckling happens at the midline of the plane and the values of (pcr = 195.83 n/m, 139.82 n/m, 73.111 n/m and 55.142 n/m ) at fiber angle are (  = 0, 30, 60 and 90) respectively. figure (6) shows the relationship between the critical load and the fiber angle of the composite plate at different fiber volume fraction and at ( l/w = 2)for the finite element analysis. it is clear from this figure that the critical load decreases in nonlinear relationship with the increase of the fiber angle in different manners depending on the volume fraction. the maximum value of ( pcr = 629.54 n/m ) at ( = 0 and vf = 40 %) while the minimum value of ( pcr = 55.142 n/m ) at ( = 90 and vf = 10 %). figure (7) shows the relationship between the critical load and fiber volume fraction of the composite plate at different fiber angles for the finite element method. it can be seen that the critical load increases with the increase of the fiber volume fraction in different manners depending on the fiber angle, where the behavior of curve at ( = 0 ) is the greatest one. at this angle the maximum value of (pcr = 629.54 n/m) at (vf = 40 %) while the minimum value of (pcr = 195.83 n/m) at (vf = 10 %). figure (8) shows the relationship between the critical load and the fiber angle of the composite plate at different fiber volume fractions and at ( l/w = 2)for the experimental work. it is clear from this figure that the critical load decreases in nonlinear relationship with the increase of the fiber angle in different manners depending on the volume fraction. the maximum value of ( pcr = 560 n/m ) at ( = 0 and vf = 40 %) while the minimum value of dr. jawad kadhim uleiwi /al-khwarizmi engineering journal ,vol.2, no. 2 pp 42-55 (2006) 46 ( pcr = 49 n/m ) at ( = 90 and vf = 10 %). figure (9) shows the relationship between the critical load and the fiber volume fraction of the composite plate at different fiber angle for experimental work. it can be seen that the critical load increases with the increase of the fiber volume fraction in different manners depending on the fiber angle, where the behavior of the curve at ( = 0 ) is the greatest one. at this angle the maximum value of (pcr = 560 n/m) at (vf = 40 %) while the minimum value of (pcr = 173 n/m) at (vf = 10 %). figure (10) shows the relationship between the critical load and the fiber angle at ( vf = 40 %) and at (l/w = 2) for the experimental and finite element analysis. it is clear from this figure that the critical load decreases in nonlinear relationship with the increase of the fiber angle. it has also been found that the maximum difference between the finite element analysis results and the experimental results ( 11 %) at ( = 0). the reason for this difference is attributed to the condition of preparing the specimens. figure (11) shows the relationship between the critical load and the fiber volume fraction at ( = 0) and at (l/w = 2) for the experimental and finite element analysis. it is clear from this figure that the critical load increases in linear relationship with the increase of the fiber volume fraction and it has also been found that the maximum difference between finite element analysis results and experimental results ( = 11 %) at ( vf = 40 %). 7.conclusion the main conclusions of the buckling analysis of the composite plates for finite element analysis and the experimental work are: (1-) critical load decreases in nonlinear relationship with the increase of the fiber angle in different manners depending on the fiber volume fraction and the maximum value of (pcr = 629.54 n/m) at ( = 0) and (vf = 40 %) for finite element analysis. (2-) critical load increases with the increase of the fiber volume fraction and the minimum value ( pcr = 55.142 n/m ) at ( = 90) and (vf = 10 %) for finite element analysis. (3-) the behavior of the critical load with fiber angle and with fiber volume fraction for experimental work is similar to the behavior of finite element analysis but here the maximum value of (pcr = 560 n/m) at ( = 0) and (vf = 40 %) the minimum value of ( pcr = 49 n/m ) at ( = 90) and (vf = 10 %). (4-) maximum difference between the results of finite element analysis and experimental work results ( = 11 %) at ( = 0) and ( vf = 40 %). 8.references [1-] c.a. featherston and c ruiz, " buckling of flat plates under bending and shear ", proc instn mech engrs, vol.212, part c, (1998). [2-] david bushnell, " buckling of shells pitfall for designers", aiaa80-0665r, vol.19, no.9, september, (1981). [3-] n.g. lyenger and s.gupta, " programming methods in structure design", (1980). dr. jawad kadhim uleiwi /al-khwarizmi engineering journal ,vol.2, no. 2 pp 42-55 (2006) 47 [4-] rais-rohani, m and marcellier, p.," buckling and vibration analysis of composite sandwich plates with elastic rotational edge restraints". aiaa journal, vol.37, no. 5, (1999). [5-] marcellier, p. and rais-rohani, m., " free vibration and buckling analysis of anisotropic sandwich plates with edges elastically restrained against rotation", proceedings of the 39th aiaa/ asme/ asce/ ahs/ asc structures, structural dynamics, and materials conference, long beach, ca, april 20-23, 1998. aiaa-98-2084-cp. [6-] timothy l.c. chen and charles w. bert " design of composite material plates for maximum uniaxial compressive buckling loads", mechanical and nuclear engineering, the university of oklahoma, norman, oklahoma, (1976). [7-] hyonny kim and keith t. kedward," a method for modeling the local and global buckling of delaminated composite plate ", composite structures, vol.44, no.1, (1999). [8-] timoshenko, stephen p. and james m. gere, " theory of elastic stability", 2nd edition, mcgrawhill book company, new york, (1961). [9-] yasui, yoshiaki," the buckling of rectangular composite plates with cutout under uniaxial and biaxial compression", proceedings the 8th international conference on composite materials, july, (1991). [10-] rouse, marshall," effect of cutouts or low-speed impact damage on the postbuckling behavior of composite plates loaded in shear", proceedings of the 31st aiaa, asme, asce, ahs, asc, structures, structural dynamics and materials conference, april, (1990). [11-] r.m., jones, " mechanics of composite material", mcgrawhill, new york, (1975). [12-] kohnke p.," ansys theory reference release 5.4", ansys, inc., (1975). dr. jawad kadhim uleiwi /al-khwarizmi engineering journal ,vol.2, no. 2 pp 42-55 (2006) 48 aij extensional stiffness terms (n/m). bij coupling stiffness terms (n). dij bending stiffness terms (n.m). e11 young's modulus in the fiber direction (n/m2). e22 young's modulus in the matrix direction (n/m2). ef young's modulus of the fiber (n/m2). em young's modulus of the matrix (n/m2). g12 shear modulus along the principal axis (n/m2). kx, ky, & kxy curvatures of the midplane (m). mx resultant moment intensity about the y-axis per unit width of the laminate crosssection (n.m). my resultant moment intensity about the x-axis per unit width of the laminate crosssection (n.m). mxy resultant twisting moment intensity about the xyaxis/unit width of the laminate cross-section (n.m). nx resultant in-plane force intensity in the x-axis/unit width of the laminate crosssection (n). ny resultant in-plane force intensity in the y-axis/unit width of the laminate crosssection (n). nxy resultant in-plane shearing force intensity in the xyaxis/unit width of the laminate cross-section (n). ijq reduced stiffness terms (n/m2). ijq transformed reduced stiffness terms (n/m2).  q reduced stiffness matrix.  q transformed reduced stiffness matrix. vf volume fraction of fiber (%). vm volume fraction of matrix (%). z coordinate measured from the midplane (m).  xyyx  ,, midplane strains.  strain vector in ply.  stress vector in ply. i stress components (n/m2). 12 shear strength along the principal axis (n/m2) 12 shear strain along the principal axis.  fiber angle (). 12,21 major and minor poisson's ratio. notation dr. jawad kadhim uleiwi /al-khwarizmi engineering journal ,vol.2, no. 2 pp 42-55 (2006) 49 figure (1): location of material (principal) coordinate system on the lamina [11]. figure ( 2 ): test apparatus and test specimen load indicator dial gauge unidirectional composite plate dr. jawad kadhim uleiwi /al-khwarizmi engineering journal ,vol.2, no. 2 pp 42-55 (2006) 50 figure ( 3 ): shell93 8-node structural shell [12]. figure ( 4 ): mesh generation and boundary conditions of the composite plate. dr. jawad kadhim uleiwi /al-khwarizmi engineering journal ,vol.2, no. 2 pp 42-55 (2006) 51 figure ( 5 ): deflection contours of the composite plates at (vf=10 %) and at different value of fiber angle.  = 0  = 30  = 60  = 90 dr. jawad kadhim uleiwi /al-khwarizmi engineering journal ,vol.2, no. 2 pp 42-55 (2006) 52 figure ( 6 ): relationship between critical load and fiber angle for finite element analysis at different volume fraction. figure ( 7 ): relationship between critical load and fiber volume fraction for finite element analysis at different fiber angle. 10 20 30 40 fiber volume fraction (%) 0 50 100 150 200 250 300 350 400 450 500 550 600 650 c ri ti c a l l o a d ( n /m ) f.e.m.  = 0  = 45  = 90 0 15 30 45 60 75 90 fiber angle (deg.) 0 100 200 300 400 500 600 700 c ri ti c a l l o a d ( n /m ) f.e.m. vf = 40 % vf = 30 % vf = 20 % vf = 10 % dr. jawad kadhim uleiwi /al-khwarizmi engineering journal ,vol.2, no. 2 pp 42-55 (2006) 53 figure ( 8 ): relationship between critical load and fiber angle for experimental at different volume fraction. figure ( 9 ): relationship between critical load and fiber volume fraction for experimental at different fiber angle. 0 15 30 45 60 75 90 fiber angle (deg.) 0 100 200 300 400 500 600 c ri ti c a l l o a d ( n /m ) experimental vf = 40 % vf = 30 % vf = 20 % vf = 10 % 10 20 30 40 fiber volume fraction (%) 0 50 100 150 200 250 300 350 400 450 500 550 600 c ri ti c a l l o a d ( n /m ) experimental  = 0  = 45  = 90 dr. jawad kadhim uleiwi /al-khwarizmi engineering journal ,vol.2, no. 2 pp 42-55 (2006) 54 figure ( 10 ): relationship between critical load and fiber angle for finite element analysis experimental at fiber volume fraction( = 40 %). figure (11): relationship between critical load and fiber volume fraction for finite element analysis and experimental at fiber angle (= 0). 0 15 30 45 60 75 90 fiber angle (deg.) 0 100 200 300 400 500 600 700 c ri ti c a l l o a d ( n /m ) f.e.m experimental 10 20 30 40 fiber volume fraction (%) 0 50 100 150 200 250 300 350 400 450 500 550 600 650 c ri ti c a l l o a d ( n /m ) f.e.m. experimental dr. jawad kadhim uleiwi /al-khwarizmi engineering journal ,vol.2, no. 2 pp 42-55 (2006) 55 تحليل األنبعاج للصفائح المركبة األحادية األتجاه ذات األساس البوليمري د. جواد كاظم عليوي قسم هندسة المواد / الجامعة التكنولوجية :الخالصة تهتم هذه الدراسة بتقيم الحمل الحرج للصفائح المركبة األحادية األتجاه ذات األسااس الباوليمري بتساتخدام طريقااة تقنيااات العناصاار المحااددو انااد ماويااا ليااح مختلفااة وكساار حجماا مختلااح لتلاا الطريقااة العمليااة و الصفائح. اذ يبين تحليل األنبعاج بان الحمل الحرج يقل بعالقاة ييار خطياة ماا مياادو ماوياة اللياح ويامداد ماا مياادو الكسر الحجم لليح. ( = 0 ( اناد n/m rcp 629.5 =بينت النتائج بان اقصى قيمة للحمل الحرج لكل وحدو طاول ( اناد n/m crp 49 =( لطريقة العناصر المحددو. بينما اقل قيمة للحمل الحرج الحارج fv % 40 =و = 90  10 =( و % fv.للطريقة العملية ) = ( اند % 11 = وكذل بينت النتائج بان اقصى فرق بين طريقة العناصر المحددو والطريقة العملية 0 40 =( و % fv .) محمد ومصطفى وعد al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 9, no. 1, p.p. 71-82 (2013) obstacles avoidance for mobile robot using enhanced artificial potential field mohamed jasim mohamed* mustaffa waad abbas** *,**department of control and systems engineering/ university of technology *email: moh62moh@yahoo.com *email: mustaffa.waad@yahoo.com (received 15 july 2012; accepted 18 february 2013) abstract in this paper, an enhanced artificial potential field (eapf) planner is introduced. this planner is proposed to rapidly find online solutions for the mobile robot path planning problems, when the underlying environment contains obstacles with unknown locations and sizes. the classical artificial potential field represents both the repulsive force due to the detected obstacle and the attractive force due to the target. these forces can be considered as the primary directional indicator for the mobile robot. however, the classical artificial potential field has many drawbacks. so, we suggest two secondary forces which are called the midpoint repulsive force and the off-sensors attractive force. these secondary forces and modified primary forces are merged to overcomethe drawbacks like dead ends and u shape traps. the proposed algorithm acquirs information of unknown environment by collecting the readings of five infrared sensors with detecting range of 0.8 m. the proposed algorithm is applied on two different environments also it is compared with another algorithm. the simulation and experimental results confirm that the proposed algorithm always converges to the desired target. in addition, the performance of algorithm is well and meets the requirements in terms of saved time and computational resources. keywords: mobile robot, local path planning, obstacles avoidance, potential field. 1. introduction the existence of robots in various types became very significant in the industrial sector and especially in the service sector. due to the growing interest of the service robots, they can achieve their mission in an environment which contains several obstacles [1]. the mobile robots have the advantage of the simplicity of manufacturing and mobility in complex environments. the capacity to move without collision in such environment is one of the fundamental questions to be solved in autonomous robot-like problems. the robot should avoid the undesirable and potentially dangerous objects. these possibilities have much interest of the subject of robot-like research [2]. the methods to plan a path for mobile robot can be classified into two types: global path planning techniques and local path planning techniques or obstacles avoidance techniques. the global path planning techniques are related to those techniques that are done before the robot moves. on other hand online obstacles avoidance techniques are associated with those techniques that are done while the robot motion [3]. artificial potential field is popular approach for obstacles avoidance. artificial potential field method (apf) is one of the mostly studied and used methods in mobile robot path planning [4]. the artificial potential field method was proposed by khatib, which is a virtual force field method. although this method is fast and efficient, it has the following drawbacks and limitations; trap situations due to local minima, no passage between closely spaced obstacles, oscillations in the presence of obstacles and oscillations in narrow passages [5]. mailto:moh62moh@yahoo.com mailto:mustaffa.waad@yahoo.com mohamed jasim mohamed al-khwarizmi engineering journal, vol. 9, no.1, p.p.71-82 (2013) 72 to overcome these limitations, several authors have tried to solve the local minima problem by presenting new potential functions so that the destination becomes the global minimum. others tried to solve these problems by combining the simple potential method with artificial intelligence models like neural network [6], genetic algorithm [7] and fuzzy logic [8]. but unfortunately these methods contribute to increase in the complexity of the algorithms. in this paper, we proposed an algorithm using a simple potential functions with specific rules and conditions, that overcome the conventional artificial potential field. the simulations of experiments verify that this algorithm is not bound to the limits as is the case with traditional artificial potential field methods. the reminder of this paper is organized as follows: section ii gives brief introduction to the traditional artificial potential field, section iii describes the problem, section iv gives the determination to the robot system that is used, section v illustrates the proposed algorithm, section vi shows the simulation of number of local path planning cases and a comparison study are given. finally, section vii introduces the conclusions. 2. a traditional artificial potential field method the basic idea of artificial potential field (apf) method is that the movement of objects in the environment is considered as a movement in the abstract artificial force field, which is composed of the attractive force field of the target and repulsive force field of the obstacle. in fact, the robot descends on the potential field according to gradient descent method to reach its destination while avoiding obstacles [9]. therefore, the artificial potential field is defined in equation (1). the robot follows this gradient of the field as shown in equation (2). = + …(1) = −( + ) …(2) where: is the attractive force of the target, is the repulsive force of the obstacle. the attractive and repulsive forces are shown in equations (3) and (4) respectively [10]. = ( , ) …(3) = ( ( , ) − ) , ( , ) < , ( , ) ≥ …(4) where: and are the gain’s coefficients of attraction and repulsion functions respectively, is the largest impact distance of single obstacle, ( , ) is the euclidean distance between the locations of robot and the target, ( , ) is the minimum distance between the affected areas of obstacle and the location of the robot. 3. problem description the problem is how to drive a mobile robot to a certain target point in an unknown environment without any collision. this means how to make the mobile robot avoids obstacles online based on the available infrared sensors readings only. 4. the robot and sensors in our algorithm, the robot is modeled as a circle with the ability of turning around its center, just like rover robots or two wheel robots as shown in figure (1). the robot is supplied with five infrared distance meters each with the range of 80 cm. the first sensor puts on the front of the robot, this sensor will be referred to as the “zero degree sensor”. the reset four sensors are put on the both sides of the zero degree sensor with angle of −40°,−20°, 20° and 40° .the robot model is shown in figure (2). fig. 1. rover mobile robot . mohamed jasim mohamed al-khwarizmi engineering journal, vol. 9, no.1, p.p.71-82 (2013) 73 5. proposed algorithm the proposed algorithm is based on the principles of artificial potential field path planning and our proposed ideas. these ideas are suggested to overcome the lack of the artificial potential field and to ensure a reliable on-line path planning. the proposed algorithm is presented as a sequence of steps as follow. 5.1. attractive force calculations before the robot starts to move the gradient descent of attractive force is calculated; then according to this gradient, the robot is directed toward the point of target. the proposed and used attractive force shown in equation (5) has small deference from the conventional equation shown in (3). as shown in equation (3), the different term is the square of the distance between the robot and the position of the target, while for the used attractive force in equation (5) this term is only the distance from the robot to the position of the target. this function is chosen to give the robot more allowance to move around the target and even go in the reverse direction when that is necessary. ( ) = ( , ) …(5) in equation (5) and are the position of the robot and the position of target respectively. the gradient of the attractive force is illustrated in equation (6). ( ) = ( , ) …(6) the scaling factor is used to increase the effect of attractive force and to prevent the sharp redirection that may cause by large repulsive forces in some cases. the factor is chosen to be 2. this choice is based on the system observation and the maximum resultant repulsive force that could apply on the robot. 5.2. collision detection after the attractive force of target point is calculated and the robot is directed according to gradient of this force, the statuses of sensors are checked to get the information about any possible collision. although the sensors may detect many obstacles, not all of these detected obstacles are considered to make collisions. in fact, the detected obstacles are elected as possible collision points. the detected point/points is/are defined as collision point/points, if and only if the conditions (7) and (8) are satisfied. × ( ) ≤ ...(7) × ( ) ≤ …(8) in equation (7) and (8) is the distance detected by the sensor and is the angle of the sensor that detects this distance. the robot step size is the straight distance that the robot moves through it after the direction of the robot is specified base on the forces applied on it. step size is initialized at first to a distance equal to sensor range (80 cm). the above two conditions are better illustrated in figure (3). fig. 3. collision points = × ( °), = × ( °). fig. 2. robot model. 80 cm 0° sensor 20° sensor 40° sensor −20° sensor −40° sensor detected point d dw dl ≤ detected point=collision point if: ≤ , mohamed jasim mohamed al-khwarizmi engineering journal, vol. 9, no.1, p.p.71-82 (2013) 74 5.3. repulsive force calculations when the collision point/points is/are specified the repulsive force from this/these point/points is/are calculated according to equation (9). ( ) = ∑ ( , ) … (9) where: is the position of robot, are the positions of collision points and is the number of detected collision points. equation (10) shows the gradient of the repulsive force. ( ) = ∑ − ( ) ( , ) …(10) the deference between the proposed and the traditional equations of repulsive force is that the largest impact distance of single obstacle is removed in the proposed equation of repulsive force. the reason for this is that the robot works in an unknown environment and the repulsive force is calculated only for the collision points that are detected by the sensors. the primary proposed attractive force and repulsive force provide a safe path for the mobile robot to reach the target point. in fact, these forces are enough when underlying environment is simple and does not contain local minimum or dead ends. therefore, extra types of secondary repulsive and attractive forces are suggested here to contribute with the primary forces. these forces are called “midpoint repulsive force” and “off-sensor attractive force”. 5.4. midpoint repulsive force the midpoint repulsive force is proposed to get the robot out of u shape traps or dead ends. it gives the robot sense of direction, like where the robot comes from and where the robot should go. the midpoint repulsive force depends on the previously detected collision points ( ). we classify the previously detected collision points ( ) into three types of points which are; xpoints, y-points and xy-points. the mechanism of classification is based on the direction and the position of the robot related to the target point at the instant of detection the collision point/points. this classification depends on two steps. the first step depends on the direction of the robot. the following three conditions determine the direction of the robot as shown in (11), (12) and (13). ( ) > ( ) … (11) ( ) < ( ) …(12) ( ) = ( ) …(13) in (11) to (12) is the direction of the robot with respect to the x-axis. the three last conditions are better illustrated in figure (4). in other word, the satisfaction of first condition (11) informs that the change in the position of the robot along the x-axis during its motion larger than the change along the y-axis. the satisfaction of the second condition (12) indicates that the change in the position of the robot along y-axis larger than x-axis. finally condition (13) satisfied if the change in the position of the robot along the x-axis and y-axis is the same. the second step depends on which of the above three conditions are satisfied. if condition (11) is true then the detected collision point/points at that instance is classified as x-point, if this point/points lies between the x-axis of the robot and the x-axis of the target. if condition (12) is satisfied the collision point/points is classified as y-point, if this point/points lies between the yaxis of the robot and the y-axis of the target. in same manner, if condition (13) is satisfied the point/points is classified as xy-point. figure (5) shows this classification. fig. 4. first step condition. (a) ( ) > ( ) = . (b) ( ) < ( ) = . (c) ( ) = ( ) = . x y (b) ( ) ( ) (a) ( ) ( ) (c) ( ) ( ) = ° mohamed jasim mohamed al-khwarizmi engineering journal, vol. 9, no.1, p.p.71-82 (2013) 75 in figure (5-b) some points are classified as xpoints because they are out of the range of y-axis of the target and the robot. the ignored point in figure (5-c) is ignored by the midpoint repulsive force because it is out of the xy-axis range of the robot and the target but this point is not ignored by the prim repulsive force. the basic purpose of this classification is to ensure that the midpoint repulsive force does not take into account the points that the robot passes them and they have no importance any more. thus, the midpoint force ignores the x-points if these points become out of the range of x-axis of robot and x-axis of target and the same for ypoints and xy-points, if they out of the y-axis range and the xy-axis range respectively. the midpoint is calculated for the as in equation (11). = (∑ ) / … (11) where: n is the number of previously saved collision points. the purpose of the midpoint repulsive force is to be an antagonist for the attractive force of target. it has the ability to reverse the direction of the robot or drive the robot away from the target point, when it is necessary. therefore, the repulsive force of the midpoint is calculated in different way. it is calculated as the negative of the distance between the robot and the midpoint as in equation (12) and the gradient of it in equation (13). ( ) = − ( , ) …(12) ( ) = − ( , ) …(13) the factor in (12) and (13) is chosen to be 1 or half of the factor of the attractive force in order to make the effect of attractive force superior to determine the direction of the robot. this almost leads the robot to the target. figure (6) shows the effect of this force. 5.5. off-sensors attractive force this force is proposed to give the robot an insistence to maintain its direction until it reaches a dead end or it goes so far from the target. furthermore, this force is also used to enhance the performance of the robot around the corners and to increase the smoothness of the resultant path (reduces the oscillations of the motion). this force is based on two classifications; classification of the motions of robot and classification of the sensors. a. robot's motions classification the motions of the robot are classified here into three classes: fig. 5. collision points classification. (a) ( ) > ( ) = . (b) ( ) < ( ) = . (c) ( ) = ( ) = . target x-point target x-points y-points target xy-points ignored (b) (a) (c) fig. 6. midpoint repulsive force effect. (a) without midpoint repulsive force. (b) with midpoint repulsive force. start start (a) (b) target target mohamed jasim mohamed al-khwarizmi engineering journal, vol. 9, no.1, p.p.71-82 (2013) 76 class 1: direct movement to the target (dm). the robot has an angle equal to zero relative to target point. class 2: clockwise movement to the target (cwm). the robot tries to reach the target and avoids the obstacles by moving clockwise direction. the target is taken as the center of motion. class 3: counter clockwise movement to the target (ccwm). the robot tries to reach the target and avoids the obstacles by moving counter clockwise. the target is taken as the center of motion. b. sensor's classification we divide the sensors except the zero degree sensor into two groups the left group or clockwise group (the -40 and -20 angle's sensors) and the right group or counter clockwise group (the 40 and 20 angle's sensors). figure (7) illustrate this classification. figure (8) shows the three classes of motions. the motion of the robot at the start point is dm and at this moment, the off-sensors attractive force is not calculated until the robot changes its direction (collision is detected). if a collision is detected, the robot due to the prime repulsive force is deviated. then, the motion of the robot is checked whether it is cwm or ccwm. at this moment, the off-sensors attractive force is calculated for the group of sensors which is nearest to the target point. this off-sensor attractive force is calculated for each step of the robot according to the assigned group until the motion of the robot altered to the dm. this means that the robot will advance to the target point with the current detected motion (cwm or ccwm) until the direct motion of the robot dm is detected again. at this moment, the calculation of the offsensors attractive force is stopped and the robot continues on its direct motion to the target. when a new collision detected again, then the algorithm is restarted in same way. after the right group of sensors is specified, the off-sensor attractive force and its gradient are calculated for the specific two sensors as in equation (14) and (15). ( ) = ∑ ( , ) × …(14) ( ) = − ( , ) × …(15) in (14) and (15) chosen to be 1, are the points of the off-sensor attractive force taken at the end of each sensor range as shown in figure (7) and is a binary flag represents the condition of the sensor; 1 for off sensor and 0 for on sensor. this force has another major importance where it reduces the effect of midpoint repulsive force. right group sensors left group sensors off-sensor attractive force points fig. 7.off-sensor attractive force. fig. 9. off-sensors attractive force effect. (a) without off-sensors attractive force. (b) with off-sensors attractive force. (a) (b) start target start target target target target (a) (b (c) fig. 8.robot motion classification. (a) dtt. (b) cwdt. (c) ccwdt. mohamed jasim mohamed al-khwarizmi engineering journal, vol. 9, no.1, p.p.71-82 (2013) 77 in fact, the midpoint repulsive force is calculated always even when the robot is far from the midpoint. this may direct the robot away from the target. so the off-sensors attractive force ensures that the robot will not go so far in its attempts to avoid the dead ends and u shape traps. figure (9) shows the effect of the off-sensors attractive force. i. direction and step size the attractive forces and the repulsive forces are used to obtain the direction of the robot only. the gradient of force is calculated according to equation (16). = −( + + + ) …(16) the direction of the robot is found according to equation (17). = …(17) when the direction of the robot is calculated, we need to calculate the step size of movement. the step size calculation is done according to two cases, these cases are; case 1: free robot motion. in this case, the sensors detect no collision and the step size is initialized to distance equal to the sensor range (80 cm). the reason for this is that, in free robot motion all we need to ensure that there is no obstacle in front of the robot within range of the sensor only. case 2: when the collision is detected. the step size is taken as the summation of the maximum detected distance and the robot width. ii. near target behavior although the proposed algorithm is enhanced to overcome drawbacks in the classical algorithm, the algorithm still has some difficulties to lead the robot to special kind of targets. when the target lies near narrow corners and when the target lies between two closed obstacles. according to the algorithm, the robot may change its direction before the robot reaches the target because of the effect of repulsive force of the near target detected points as shown in figure (10). thus, when the robot becomes at a distance from the target less than the sensor range, the behavior of the algorithm is changed. the midpoint repulsive force and the off-sensors attractive force will no longer active. the step size will be equal to the distance from the robot to the target. this will lead the robot to the target without any additional actions. for better understanding of the proposed algorithm, the previous steps of algorithm are illustrated in flowchart shown in figure (11). fig. 10. near target behavior. (a) without near target behavior. (b) with near target behavior. target start target start (a) (b) mohamed jasim mohamed al-khwarizmi engineering journal, vol. 9, no.1, p.p.71-82 (2013) 78 6. simulation and results this section is assigned to perform a simulation on some path planning problems using the proposed algorithm. two examples with two different environments are studied. in addition, a comparison study is done between the proposed algorithm and the algorithm that is proposed in [2]. this simulation is performing via a vc++ using direct2 library. environment 1: this environment has length of 6.3 m and width of 5.6 m. the results of the two examples are shown in figures (12, 13). fig. 12. simulation result of environment 1, example 1, start point is (0.245m, 0.245m) and goal point is (6m, 5m). environment 2: this environment is generated randomly by random environment generator algorithm. the obstacles are represented by circles. there are 80 obstacles with radiuses in range of 0.12m to 0.9 m. the environment has length of 17.15 m and width of 14.7m. the results of the two examples are shown in figures (14, 15). start target fig. 11.the flowchart of proposed algorithm. no yes no yes no save the points calculate rep. force no end goal reached calculate rep force yes calculate att. force no collision detection calculate attractive force no yes near target start direct movement to target (dm) yes read sensors find nearest sensors group to the target off-sensor att. force step size calculation read sensors midpoint rep. force yes no. of saved points > 0 midpoint rep force direct movement to target (dm) mohamed jasim mohamed al-khwarizmi engineering journal, vol. 9, no.1, p.p.71-82 (2013) 79 fig. 13. simulation result of environment 1, example 2, start point is (6.07m, 1.88m) and goal point is (3.6m, 3.1m). fig. 14. simulation result of environment 2, example 1, start point is (6m, 7.3m) and goal point is (12.7m, 9.75m). comparison study: this comparison is done between the proposed algorithm in [2] and our proposed algorithm. the proposed algorithm in [2] uses q-learning algorithm and fuzzy logic to find the path to the target based on the reading of thirteen sensors. fig. 15. simulation result of environment 2, example 2, start point is (10.7m, 2.3m) and goal point is (0.9m, 4.2m). two examples are taken for comparison. the results of the q-learning algorithm are shown in figure (16) and figure (17). the two examples are re-simulated using our proposed algorithm and the results are shown in figure (18) and figure (19). the comparison study shows that our proposed algorithm develops paths which are the same or better than the paths of the q-learning algorithm. in addition, our algorithm does not need to use any artificial intelligent system like fuzzy or neural network. fig. 16. the q-learning algorithm results, example 1, [2]. start target start targe start target target start mohamed jasim mohamed al-khwarizmi engineering journal, vol. 9, no.1, p.p.71-82 (2013) 80 fig.17. the q-learning algorithm results, example 2, [2]. fig. 18. the re-simulation of q-learning algorithm example 2 by the proposed algorithm. fig. 19. the re-simulation of q-learning algorithm example 3 by the proposed algorithm. 7. conclusion in this paper, we proposed an algorithm to solve the problem of finding a path between two specific points in the totally or partially unknown environment. the required data for the algorithm are; the start point, the target point, and the readings of five infrared distance meters which are fixed in the front of the robot within angles equal to (− ,− , 0, , ). the main points that are important to refer to for the proposed algorithm are: • since, the classical artificial potential field suffers from some drawbacks; we suggested secondary forces, the off-sensors attractive force and midpoint repulsive force. these suggested forces are merged with forces of classical artificial potential field. these additional forces are submitted to a certain rules and conditions, to ensure a smooth and safe path to the target. • in addition, the proposed algorithm follows simple calculations and conditions without any searching or optimization method. thus, it is possible to apply this algorithm on micro controllers like pic or avr micro controllers. • the simulation results show that the proposed algorithm is fast and efficient. in addition, it overcomes the drawbacks and limitations of target start start target start target mohamed jasim mohamed al-khwarizmi engineering journal, vol. 9, no.1, p.p.71-82 (2013) 81 traditional artificial potential field. the proposed algorithm has the capabilities like escapes from local minima, passes between closely spaced obstacles, damps oscillations in the presence of obstacles and damps oscillations in narrow passages. • finally, the proposed on line path planning algorithm always go to the target within minimum distance. furthermore, the comparison study shows that our proposed algorithm is better than the algorithm that uses artificial intelligence system. 8. references [1] i. ulrich and j. borensstein, “the guidecaneapplying mobile robot technologies to assist the visually impaired”, part a : system and human, vol. 31, 2, pp. 131-136, 2001, ieee transaction on system, man and cybernetics. [2] lazhar khriji, farid touati, kamel benhmed, and amur al-yahmedi, “qlearning based mobile robot behaviors coordination”, november 5-7, 2010 – sousse, tunisia, international renewable energy congress. [3] cameron, “obstacle avoidance and path planning”,1994, industrial robot: an international journal, vol: 21(5):p.9-14. [4] o. khatii, "real-time obstacle avoidance for manipulators and mobile robots", 90-98, 1986, hitcmational jomal of robotics research vol. 5, 110. [5] hossein adeli, m.h.n. tabrizi, alborz mazloomian, ehsan hajipour and mehran jahed,” path planning for mobile robots using iterative artificial potential field method”, 2011, ijcsi international journal of computer science issues, vol. 8, issue 4, no 2, july. [6] n. sadati, j. taheri, “hopfield neural network in solving the robot motion planning problem”, iasted intl. conf. on applied informatics (ai2002), innsbruck, austria, feb 2002. [7] h. mahjoubi, f. bahrami, and c. lucas, “path planning in an environment with static and dynamic obstacles using genetic algorithm: a simplified search space approach,” ieee congress on evolutionary, pp. 2483-2489, 2006. [8] mohammad abdel kareem jaradat, mohammad h. garibeh and eyad a. feilat, “autonomous mobile robot dynamic motion planning using hybrid fuzzy potential field”, springer, 9 june 2011. [9] he bing, lid gang and nan nan li yan, “a route planning method based on improved artificial potential field algorithm”, ieee, 2011. [10] o.khatib, "real-time obstacle avoidance for manipulators and mobile robots," intl. j. of robotics research, vol. 5, no. 1, pp 90-98, 1986. )2013(71-82 ، صفحة1، العدد9مجلة الخوارزمي الھندسیة المجلد وعد عباس ىمصطف 82 تجنب العوائق للروبوت النقال باستخدام مجال القوى االصطناعي المعزز ** وعد عباس ىمصطف* جاسم محمد محمد الجامعة التكنولوجیة /قسم ھندسة السیطرة والنظم**،* moh62moh@yahoo.com: البرید االلكتروني* mustaffa.waad@yahoo.com : ينااللكتروالبرید ** صةالخال ھذا الٌمِخطط أُقترح ألِیجاد الَحلوْل ِبسرَعة عاِلیة وَفوریْة لَمشاكْل َتخطیْط َطریْق . جاْل القوى األصِطناعْي الٌمَعززفي ھذا الَبحْث َتْم َتقدیْم ُمِخطط َم ُیمثل ُكال ِمْن القوة الَتقلیدْي أن َمجال القوْى الألصطناعي. َعوائْق َغیر َمعروفة الَمواقع واألحجام الُروبوْت الَنقاْل ِعندْما َتكوْن الِبیئة الَمدروْسة َتحتوي َعلى اِنیة فاْن َمجال مْن ناحیة ث. ھذِه القوى ُممكْن ان ُتعتبر َدلیْل األِتجاه األساسي للُروبوت الَنقال .الَنبضیة ُنتیجْة العائْق الُمكتشف و القوة الَجاذبة الناِتجة مْن الَھدف ھاتان . ولذا أقَترحنا قوَتین ثاَنویتین واللتین ُسِمیتا قوة ُنقطة الَوسط النبضیة وقوة الَجذب للمتحسس الخامل. َیمتلك ِعدة َمشاكل الَتقلیدْي القوى األصِطناعي أن الَخوارزمیة الُمقترحة تكتْسب . ھایة الَمیتة وَمصیدة َحذوة الفرسالقوتان الثانویتان والقوى االساسیة المحسنة قد تم دمجھا للتغلب على الَمشاكل َمثل الن أْن الَخوارزِمْیة . َمتر ٠.٨وِبَمجاْل أكتشاْف الَمعلوماْت َعْن الِبیْئة الَغیر َمعُروفة ِبواِسطة َجمْع القراءات مْن َخمْسة ُمتَحِسساْت َیعَملوْن باألشْعة الَتحْت الَحمراْء أن الُمْحاكاة والنتائْج الَتجریبْیة ُتؤكْد أْن الَخوارزمْیة الُمقترْحة دائما ُتالقْي . َكذلْك َقد َتم ٌمقارنِتھا َمْع َخوارزمیْة أخرى قت على ِبیئتْین ُمختلفتیْنالُمقترحة َقدُ ُطب .ْث َتقلیْل الَزمْن والُجھد الِحسابْيَباألضافة الْى َذلك أن أداْء الَخوارزمیة َجیدًا وُیوفْي الُمَتطلباْت مْن َحی. الَھدْف الَمطلوْب mailto:moh62moh@yahoo.com mailto:mustaffa.waad@yahoo.com 90-99حيدر هادي al-khwarizmi engineering journal,vol. 13, no. 1, p.p. evaluations of potable water t using electrochemical impedance spectroscopic method haider chemical engineering department e(received 31 july https://doi.org/10.22153/kej.2017.12.005 abstract the aim of this paper is to investigate and discuss the mechanisms of corrosion of epoxy coatings used for potable water tanks. two distinct types of jotun epoxy coatings: tankguard 412 contain penguard hb contained polyamide cured epoxy spectroscopic (eis) method. the porosity of epoxy coatings was determined using eis method. the obtained results showed that the two epoxy coatings have excellent behavior when applied and tested in potable water of basrah city. polyamine is more resistance to water corrosion compared to polyamide curing epoxy and ha microscopic inspection after test showed that the polyamine cured epoxy has blistering while the surface of polyamide cured epoxy showed pitting and blisters. keywords: corrosion mechanism , epoxy coats, 1. introduction large tanks for storing potable water are spread in all locations of iraq provinces. storage tanks serve two major purposes, one is to provide storage volume and the other is to provide pressure to the distribution system [1]. most tanks are built by welding stainless steel such as 304, aisi 316 and 316 l because it’s inert and corrosion-resistant in nature makes it an ideal material for contact with potable drinking water[2]. lining by epoxy coats are the most effective method used to protect water storage tanks plate from corrosion and have been a cost effective way of preventing leaks. one of the methods used test the corrosion of the coatings electrochemical impedance spectroscopy (eis) method. various parameters effect on epoxy coating corrosion can be obtained using eis test like impedance and porosity of coatings. is an important parameter that should be assessed to estimate their quality of coatings. porosity of khwarizmi engineering journal,vol. 13, no. 1, p.p. 9099 (2017) potable water tanks epoxy coatings performance using electrochemical impedance spectroscopic method haider hadi jasim engineering department, college of engineering, basrah university, basrah -mail: raidhani73@yahoo.com july 2016; accepted 28 december 2016) https://doi.org/10.22153/kej.2017.12.005 investigate and discuss the mechanisms of corrosion of epoxy coatings used for potable water tanks. two distinct types of jotun epoxy coatings: tankguard 412 contained polyamine cured epoxy polyamide cured epoxy, were tested and studied using the electrochemical impedance the porosity of epoxy coatings was determined using eis method. the obtained results that the two epoxy coatings have excellent behavior when applied and tested in potable water of basrah city. polyamine is more resistance to water corrosion compared to polyamide curing epoxy and has high impedance values. that the polyamine cured epoxy has blistering while the surface of polyamide poxy coats, porosity, potable water, , eis method. tanks for storing potable water are . storage ne is to provide storage volume and the other is to provide most tanks inless steel such as astm inert and an ideal potable drinking are the most effective tanks plate and have been a cost effective way s used to is the electrochemical impedance spectroscopy (eis) various parameters effect on epoxy using eis test porosity is an important parameter that should be assessed to estimate their quality of coatings. porosity of the coating is strongly related to the corrosion resistance of coats [3]. a number of papers have been published on the potable water steel tank and coatings. leidheiser [3] show that the general range of the impedance for good coating > 10 whereas poor coatings have impedance of < 10 ohm.cm2. tato et al. [4] developed an electrochemical procedure to find the porosity of coatings. they suggest that the porosity can be found by comparing the polarization resistance of the uncoated and coated substrate at constant potential. ramirez et al. [5] studied protection of four types of epoxy coating used for navy steel using eis method. the obtained results show that it is possible to get information concerning the disposal of corrosion under each coating. mathiesen et al. [6] studied low chlorine of drinking water in corrosion of 316 steel and show that all corrosion process is a combined by microbial effect on corrosion rate. havn et al. [7] study the effect of both chloride and temperature on corrosion process of steel 316l in fresh water. they showed al-khwarizmi engineering journal performance using electrochemical impedance spectroscopic method basrah investigate and discuss the mechanisms of corrosion of epoxy coatings used for potable polyamine cured epoxy and re tested and studied using the electrochemical impedance the porosity of epoxy coatings was determined using eis method. the obtained results that the two epoxy coatings have excellent behavior when applied and tested in potable water of basrah city. high impedance values. that the polyamine cured epoxy has blistering while the surface of polyamide the coating is strongly related to the corrosion papers have been published on water steel tank and coatings. leidheiser [3] show that the general range of the impedance for good coating > 106 ohm.cm2 s poor coatings have impedance of < 106 [4] developed an electrochemical procedure to find the porosity of coatings. they suggest that the porosity can be found by comparing the polarization resistance of ate at constant [5] studied corrosion protection of four types of epoxy coating used for navy steel using eis method. the obtained results show that it is possible to get information concerning the disposal of corrosion under each [6] studied the effect of low chlorine of drinking water in corrosion of 316 steel and show that all corrosion process is a combined by microbial effect on corrosion rate. [7] study the effect of both chloride perature on corrosion process of steel ed that a different pdf created with pdffactory trial version www.pdffactory.com https://doi.org/10.22153/kej.2017.12.005 mailto:raidhani73@yahoo.com https://doi.org/10.22153/kej.2017.12.005 http://www.pdffactory.com http://www.pdffactory.com haider hadi jasim al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 9099 (2017) 91 type of corrosion occurs. francis et al. [8] studied and discussed the selecting of alining used in potable water tanks. they showed that relining of tank bases using fiber glass matt embedded in solvent less epoxy fiber glass provide optimum strength for the corroded bases, and solvent less epoxy resin good protection to the steel base along with ease of applications. doolittle [9] reviewed some of the long-life coating systems used as lining for the water tank exteriors and interiors. then showed a relative comparison of salient application and performance properties. duraisamy et al. [10] prepared and studied corrosion behaviors using eis method the primer hybrid coating from epoxy resin pigmented and zinc phosphate cured with polyamide. results indicate that the primer coating had good corrosion resistance. sara et al. [11] studied using scanning electron microscopy technique the beeswax-colophony blended coating for drinking water distribution tanks. they found that this blend could be considered as a novel green organic coating and have good corrosion barrier even in aggressive environments. the current work aimed to evaluate the protecting performance against potable water of two types of epoxy coatings using electrochemical impedance spectroscopy method. mechanism of corrosion process of epoxy coats in potable water was investigated and discussed in detail. 2. experimental procedure 2.1. types of epoxy coatings epoxy coatings consist of two parts that are mixed prior to use in coating application to develop the characteristic required for coatings. these two parts are an epoxy resin which is crosslinked (base) and a curing agent (hardener). two types of commercial epoxy coatings were used in this studies and one type used as primer undercoats. these coatings are: apenguard primer comp. a, pm3192, is a twopack epoxy primer based on a high molecular weight epoxy resin made by jotun henry clark ltd, uk. btankguard 412, this is a two component solvent free polyamine cured epoxy coating. this type has thickness in the range 150 to 200 μm. cpenguard hb is a high build, two pack polyamide epoxy coating based on epoxy resin with high molecular weight. the film thickness in the range 80 to 150 μm . the two coats tankguard 412 penguard hb are made by jotun paints company of emirates llc, sharjah, u.a.e. refer to these two type of coats as: tankguard 412 model a, penguard hb model b. 2.2. specimen preparation and coats the steel used to constriction of potable water tanks are those of the chromium-nickelmolybdenum, in particular the stainless steel grade aisi 316 (en 1.4401), this types is suitable for water storage tanks and its available on the iraqi market. the addition of a certain percent of molybdenum metal to this type improves the corrosion resistance. table 1 shows the chemical composition of aisi 316 steel [12]. table 1, the percentages of the constituent elements of aisi 316 steel [12]. element mass % cr 0.08 c 0.08 max ni 10-14 n 0.1 mn 2 mo 2-3 si 0.75 p 0.045 the tests samples have circular shape with diameter of 2 cm and thickness of 5mm. figure 1 shows specimens before and after coats. fig. 1. photograph of specimens before and after coats (single and double layers) for eis test. pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com haider hadi jasim al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 9099 (2017) 92 for coating process, first, the primer layer was coat and then the two classes of jotun coatings models a and b were applied by airless spray to steel surface at nominally standard dry film thicknesses as given by manufactured company. the main function of the primer was to maximize adhesion to the coating. the epoxy coating thickness is measured using paint thickness tester (gain express holdings ltd, china) to ensure the coatings thickness in range of uses. the thickness as average value of the single and double coating layers is 260 μm and 375 μm of the model a and b receptively. the epoxy coated specimens were left to cure for 15 days at 25oc and atmosphere pressure. a total 15 specimens were used for testing. 2.3. the electrochemical impedance spectroscopic (eis) corrosion test electrochemical impedance spectroscopy is considering one of the recent tools which were commonly used in the corrosion test of organic coatings. eis used to determine the resistance and impendence of coatings and then determine the protective performances of coatings [13]. in eis method, an ac potential was applied to an electrochemical cell. the current pass through the cell electrodes was measured and from this current the electrochemical impedance was obtained. a small excitation signal is usually used during eis test. small amplitude of sinusoidal excitation signal with variable frequency is superimposed to the corrosion potential has the form [13]: ∆e = |∆��| ��� (� �) … (1) and � = 2�� … (2) where f: the radial frequency in (hz) of the applied signal. e: voltage of electrical resistance. eo: amplitude of the excitation signal. t: time in second. this excitation induces a sinusoidal current ∆i having ∆io amplitude with a phase shift ∅with respect to the applied potential: δ� = |δ��| sin(� � − �) … (3) these values of a sinusoidal applied voltage ∆e and a sinusoidal current ∆i can be represented in the complex plane as: ∆� = ∆��� + � ∆��� … (4) ∆i = ∆i�� + i ∆i�� … (5) at any frequency the impedance is complex number because δ� contains a phase shift ∅ and defined as: δz = ���� = z�� + z�� … (6) the impedance can be represented by a modulus z and a phase angle shift φ: |z| = �z��� + z��� … (7) tanϕ = ������ … (8) the impedance data can be represented by two methods: -nyquist plot: the imaginary part of impedance zim is plot as a function of real part zre. -bode plot: the absolut values of impedance (log |z|) and phase angle ∅ is plot as a function of log frequency (log f). eis measurements were carried out on coated and uncoated samples exposed to potable drinking water, for periods up to 24 hr. and 25oc. the eis corrosion test instrument consists from the autolab pstat 30 potentiostat system computer control operated by the general purpose software (gpes) version 4.9 as shown in fig.2. this eis apparatus foundat chem. eng. dept. of tehran2 university of iran. the autolab is connecting to glass cell (0.5l) have three electrodes with a coats specimen as the working electrode; a reference electrode contain silver/silver-chloride saturated solution and a concentric platinum ring as the counter electrode. the impedance measurements in all cases were carried out over a frequency range of 0.1 hz to 500 hz using 10mv amplitude of sinusoidal voltage in order to minimize the external interference on the system. the coating surfaces were macroscopic view after test using a computerize carl zeiss jena imaging system fig.3, provided by microscope and camera smart technical has resolution of 22 mega pixels. the materials compositions of basrah potable water are analysis using the spectrophotometer and shown in table 2. the ph and tds values of potable water tested determine laboratory and have a values of ph = 8.46 and tds = 115 ppm respectively. the concentration of dissolved oxygen determined not exceeds of 5 mg/l. pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com haider hadi jasim al-khwarizmi engineering journal, vol. 13, no. table 2, materials analysis of basrah liquefaction water. element concentrate cr 12 ppm cu 0.01 ppm ni 0.76 ppm al 0.19 ppm fe 0.2 ppm mn 4 ppm fl 1.3 ppm na 25 ppm cl 715.09 mg/l ca 30 mg/l mg 12 mg/l fig. 2. eis apparatus test. fig. 3. imaging devices of simple’s surfaces. 3. evaluation the porosity of epoxy coatings porosity are set of gaps in the coatings that can contain fluid (liquid or gas). distinguishes in two types: porous cracks and gaps. among various techniques, the eis method has been used because it provides quantitative heater auto-lab cell and electrodes khwarizmi engineering journal, vol. 13, no. 2, p.p. 93 materials analysis of basrah liquefaction urfaces. evaluation the porosity of epoxy in the coatings that can porosity distinguishes in two types: porous cracks and gaps. among various techniques, the eis method has been used because it provides quantitative results via a simple electrochemical apparatus [14]. the porosities (p %) of the coatings were calculated to assist in comparison and to determine the effective barrier properties of the coatings using the following formula [15] : p = ��� rc * 100% ���and�� : the polarization resistance of the uncoated and coated metal substrate respectively 4. results and discussion figure 4 shows the variation of of the uncoated aisi 316 stainless steel and coatings in case of single and double layers of two types of epoxy coats with time for 24 h of eis test at frequency 0.1 hz. as shown, continuous decreases in the impedance of immersion increasedue to diffusion of destructive ions, water molecules and other atoms like chloride through the coating. as shown the model a double layer initially has very high impedance. however, its impedance has small drops consistently with time, so this means that the corrosion protects and barrier of this coating was high through applications. model a single layer and the two models of b show large increment at first period of test, this means a large water uptake in the film of coating. after 15 h of test all specimens shows very small decrease increments in impedance. it can be note that the form of the difference in impedance between two layers coats and single layer for model a very large, especially after 24 h of the test. the z values are 55 and 13 *106 ω.cm2 two layers and single layer for model a respectively. for the model b, the between the state of the single and double layers is large at the beginning of the test and then decreases after 14 h after the start of the test. the value of z of the state of the single layer is 7.8 *106 ω.cm2. while the 316 stainless s z value of 6.6*106 ω.cm2and the difference between them and the state of the single layer of model b is rather small. heater cell and electrodes , p.p. 9099 (2017) results via a simple electrochemical apparatus %) of the coatings were calculated to assist in comparison and to determine the effective barrier properties of the coatings using the following formula [15] : … (9) : the polarization resistance of the uncoated and coated metal substrate respectively. figure 4 shows the variation of impedance (z) of the uncoated aisi 316 stainless steel and coatings in case of single and double layers of two types of epoxy coats with time for 24 h of eis test at frequency 0.1 hz. as shown, there are continuous decreases in the impedance with time of immersion increasedue to diffusion of destructive ions, water molecules and other atoms as shown the model a double layer initially has very high impedance. however, its impedance has small drops consistently with time, so this means that the corrosion protects and barrier of this coating was high through applications. model gle layer and the two models of b show large increment at first period of test, this means a large water uptake in the film of coating. after 15 h of test all specimens shows very small decrease increments in impedance. it can be note that the difference in impedance between two layers coats and single layer for model a very large, especially after 24 h of the test. the z 2 for the case of two layers and single layer for model a respectively. for the model b, the difference of z between the state of the single and double layers is large at the beginning of the test and then decreases after 14 h after the start of the test. the value of z of the state of the single layer is 7.8 . while the 316 stainless steel showed and the difference between them and the state of the single layer of pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com haider hadi jasim al-khwarizmi engineering journal, vol. 13, no. fig. 4. impedance of specimens of uncoated steel and coats by single and double layers of two models as a function of time at 0.1 hz and 25°c. figures 5 and 6 show comparisons of the experiment bode plot, i.e. logarithm of impedance and the phase angle as function of the logarithm of frequency for the two types of epoxy coats in case of single and double layers of the eis as indicated in fig.5, when the frequency increased drastically, that value of impedance decreases. this behavior could be due to the rigidity of the epoxy coatings. the fig.5 consists from two parts, the high-frequency impedance behavior represents the coating characteristics and that of low-frequency part of impedance represents the corrosion reactions occurring at the coating surface. the initial values of impedance in the low frequency range i.e. 0.1 hz of the impedance spectra amounting for single and double layers of model a and b are 17.6, 116.5, 15.2 and 13.98 respectively. the value of impedance for astm 316 stainless steel is 11.64 at first of test of time of fig. 5. the maximum phase angle occurred at approximately values 73.2, 67.1, 60.9 and 55.4 respectively. at a small frequency range with phase angles less than 35o could be observed in the bode-phase diagrams. despite these observations, phase angles were always smaller than 90o, which would be an indication of a resistance behavior. when the phase angle close to 90°, the sample tends to be have good physical barrier properties. this double layer coat of model a has good corrosion resistance properties compared to model b. khwarizmi engineering journal, vol. 13, no. 2, p.p. 94 4. impedance of specimens of uncoated steel and coats by single and double layers of two at 0.1 hz and 25°c. figures 5 and 6 show comparisons of the experiment bode plot, i.e. logarithm of impedance and the phase angle as function of the logarithm of frequency for the two types of epoxy coats in case of single and double layers of the eis test. as indicated in fig.5, when the frequency increased drastically, that value of impedance this behavior could be due to the rigidity of the epoxy coatings. the fig.5 consists frequency impedance the coating characteristics and frequency part of impedance represents the corrosion reactions occurring at the the initial values of impedance in the low frequency range i.e. 0.1 hz of the impedance single and double layers of model a and b are 17.6, 116.5, 15.2 and 13.98 respectively. the value of impedance for astm 316 stainless steel is 11.64 at first of test of time 5. the maximum phase angle occurred at .9 and 55.4 respectively. at a small frequency range with could be observed in phase diagrams. despite these observations, phase angles were always smaller , which would be an indication of a when the phase angle close to 90°, the sample tends to be have good physical barrier properties. this double layer coat of model a has good corrosion resistance properties fig. 5. comparison of impedance of uncoating, single and double layer coatings of the two models as a function of log f at 25°. fig. 6. phase angle in degrees of uncoating, single and double layer coatings of the two models as a function of log f at 25°. the polarization resistance r quantitative parameter to identify the corrosion resistance of coats under certain circumstances. high rp of coats means high corrosion resistance while low rp means low corrosion resistance. the values of rp of coats are determined from nyquist plots. the nyquist plots is obtained by plot the imaginary part of the impedance against the real parts and takes the characteristic of semicircle shape at lower frequency values as shown in fig.7. due to the nature of semicircle shape, the polarization resistance rp is obtains as the point which the extension of semicircle touches the x axis. at the high frequency intercept, or close the plot origin, the real axis value gives the potable water resistance. the low frequency intercept of 0 10 20 30 40 50 60 70 80 -0.15 0.15 0.45 0.75 1.05 1.35 1.65 1.95 model a double layer model a single layer model b double layer model b single layer uncoated ph as e an gl e ( log f , p.p. 9099 (2017) comparison of impedance of uncoating, single and double layer coatings of the two unction of log f at 25°. 6. phase angle in degrees of uncoating, single and double layer coatings of the two models as a the polarization resistance rpis useful as a quantitative parameter to identify the corrosion resistance of coats under certain circumstances. of coats means high corrosion resistance means low corrosion resistance. the f coats are determined from nyquist plots. the nyquist plots is obtained by plot the imaginary part of the impedance against the real parts and takes the characteristic of semicircle shape at lower frequency values as shown in emicircle shape, the is obtains as the point which the extension of semicircle touches the xat the high frequency intercept, or close the plot origin, the real axis value gives the potable water resistance. the low frequency intercept of 2.25 2.55 2.85 3.15 pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com haider hadi jasim al-khwarizmi engineering journal, vol. 13, no. the real axis provides a summation of the coats polarization resistance and the potable water solution resistance. therefore, the semicircle diameter will equal to the polarization resistance. to find a point of touch of extension of semicircle with the x-axis from the nyquist plots utilizing the data of fig.7 and by using simple computerize curve fitting procedure by microsoft axial 2010 programs to extrapolation of the relatively high frequency semicircular data to rp at the zero frequency restrict. in the same method the polarization resistance of aisl 316 stainless steel was determined and shown in fig.8. then eq.9 to calculate the porosity of coatings. results ofporosity values, polarization resistance of coatings and uncoats aisl 316 steel are given in table 3. fig. 7. nyquist plot of the imaginary vs. real impedance for the uncoated and coats single and double layers of two types of models at 25°. fig. 8. nyquist plot of the imaginary vs. real impedance for aisi 316 stainless steel at 25°. khwarizmi engineering journal, vol. 13, no. 2, p.p. 95 the real axis provides a summation of the coats polarization resistance and the potable water nce. therefore, the semicircle diameter will equal to the polarization resistance. to find a point of touch of extension of semicircle axis from the nyquist plots utilizing the data of fig.7 and by using simple computerize e by microsoft axial 2010 programs to extrapolation of the relatively high at the zero in the same method the polarization resistance of aisl 316 stainless steel then use of eq.9 to calculate the porosity of coatings. the results ofporosity values, polarization resistance of coatings and uncoats aisl 316 steel are given 7. nyquist plot of the imaginary vs. real ingle and odels at 25°. plot of the imaginary vs. real teel at 25°. table 3, polarization resistance and porosity of the two models at 25°. quantity cases polarization porosity resistance % (mω. cm2) uncoated 783 ---- model a 8400 9.32 (single layer) model a 8750 8.95 (double layer) model b 7700 10.17 (single layer) model b 7870 9.95 (double layer) from table 3, it’s clear that the model a has lower degree of porosity in the case of single layer 9.32 % while that for model b is 10.17 %. the used of double layer coats reduce the porosity a small values for model b about 0.2 % and model a by about 0.37 %. the difference polarizations resistance between single and double layers of two types of epoxy coatings is not very large, i.e. in model a 350 mω.cm b 170 mω.cm2. this attributed to that the thicker films of epoxy coats should allow greater amount of water to be absorbed and then increase the release electron from specimen surface during eis test.the values of coating porosity have been related to the number of pores or capillary channels perpendicular to the substrate surface through which the electrolyte reaches the interface. the low porosity of the model a coating reduces the extent of surface charging, which may contribute to the observed increase in impedance of coats. polyamides curing epoxy coating layers are much more open in terms of their chemi structure because of their large distances between amine groups in the chemical chain. they are more flexible. this open structure of the curing agent’s results in reduces resistance to corrosion process. polyamines curing epoxy coats are relatively small, low molecular weight compounds as compared with epoxy resins. thus, the crossing over produced by the reaction of both components generates a three dimensional network that, after solvent , p.p. 9099 (2017) polarization resistance and porosity of the two polarization porosity ---- 9.32 8.95 9.95 clear that the model a has lower degree of porosity in the case of single layer 9.32 % while that for model b is 10.17 %. the used of double layer coats reduce the porosity a small values for model b about 0.2 % and model a by about 0.37 %. the difference in polarizations resistance between single and double layers of two types of epoxy coatings is not very ω.cm2 and in model . this attributed to that the thicker films of epoxy coats should allow greater amount ter to be absorbed and then increase the release electron from specimen surface during eis test.the values of coating porosity have been related to the number of pores or capillary channels perpendicular to the substrate surface te reaches the interface. the low porosity of the model a coating reduces the extent of surface charging, which may contribute to the observed increase in polyamides curing epoxy coating layers are much more open in terms of their chemical structure because of their large distances between amine groups in the chemical chain. consequently they are more flexible. this open structure of the curing agent’s results in reduces coatings polyamines curing oats are relatively small, low compounds as compared with epoxy resins. thus, the crossing over produced by the reaction of both components generates a three dimensional network that, after solvent pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com haider hadi jasim al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 9099 (2017) 96 evaporation, settles down on the substrate forming a very smooth surface. one of the important parameters affecting the corrosion rate of stainless steel and epoxy coats exposed to water is the deposition of soluble salts such as calcium, magnesium and chlorides. from table 2, the basrah drinking water have various concentrations of calcium, magnesium and sodium salts. calcium is dissolved in water and initiates limestone deposits, while the magnesium is dissolved and initiates calcium magnesium carbonate camg(co3)2. water that contains high calcium or magnesium salts is less corrosive, because the minerals tend to coat and protect the inside of interior tanks. water contains sodium salts does not coat the plate of tanks and consequently is more corrosive. reactionsof calcium, magnesium, sodium and chloride with water are given by the following equations: mg(s) +2h2o(g) mg(oh)2(aq) + h2(g) … (10) ca(s) +2h2o(g) ca(oh)2 (aq) + h2 (g) … (11) 2na(s)+2h2o 2naoh(aq) + h2(g) … (12) cl� + h�o hocl + cl� + h� … (13) hocl acid resulting from reaction (13) is a weak acid which dissociates in water as: hocl clo� + h� … (14) in all reaction above is accompanied by release hydrogen which increase ph values and increase corrosion rate of water. figs. 9 show the microscopic inspection of uncoated and coated specimens surface after 6 hr. of eis test at 0.1 hz. fig. 9-b and c., blisters was observed in the coating surface of both single and double layers of model a. the water absorption by epoxy coats leads to swelling of the coating and when this occurs locally, blisters may form and water may accumulate at the interface. these water accumulations are increased the charge transfer during test and reduced the impedance of coats. water ions diffuse through coatings makes the coated surface metal in contact with the water. the steel substrate under blaster was lost. adhesion losses at the metal-coats interface eventually occur, and the onset of metal corrosion reactions will happen at the buried metal surface. bubbling is usually caused by the air pockets beneath the surface of the epoxy coat. during test, the air underneath coat expands and pushes the layer upward. fig. 9-d and e, for single and double layer model b, it is appear that the coating surface have some pitting and blisters compared to model a. the pits have black corrosion product mainly fe3o4. fig. 9. surface morphologies of specimens before and after coats tested by eis method. mechanism of corrosion the mechanism of corrosion suggested that the reaction occur between different compositions of water components and epoxy coats directly. this reaction accompanied by release of electrons to water solution and degradation of epoxy coats. the motivational force to corrosion reactions processes are voltages inflicted during eis test and self-ions tendency to reactions.fig.10 shows the mechanism of corrosion. as indicated from fig.10, water chargedis transported through the coating and causes the corrosion process by two methods: convection through the pores and coating imperfections reaching to metal surface and by diffusion through the epoxy coats. the reaction between amines and water components can be represented by the following chemical reactions: pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com haider hadi jasim al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 9099 (2017) 97 x − nh�+ hoclnh�cl + → x − oh … (15) x − nh� + h�o x − nh�� + oh� ... (16) x − nh� + oh� x − nh + h�o ... (17) x − nh� + h+ x − nh� ... (18) x − nh�+ cl x − nh��cl� ... (19) x − nh� + nacl x − nhna + hcl … (20) x − nh� + mg x − mg − nh2 … (21) x-mg-nh2 + h�o x-h + mg(oh)nh2 … (22) x − nh�+ no3 hno3 + x-nh … (23) x − nh� + co� x − nh��coo� … (24) x − nh�+ 2 o� x − no�+ h2o2 … (25) where x is any function groups. fig. 10. proposed mechanism of corrosion process in epoxy coating. the primary amine consists of a nitrogen atom linked to one alkyl group by a weak van der waals bond and to the two hydrogen atoms by hydrogen bonds. interaction with sodium hydroxide salt frees a strong hcl acid and this increases the ph of the potable water and increases the corrosion rate process. reaction between amine and magnesium produce x-mgnh2 which is unstable and dissolve in water to mg(oh)nh2. carbon dioxide dissolved gasreacts with epoxy coating and generates some of carbamate derivative which are unstable compounds which cause low epoxy coats adhesion with metal and water-spotting of coats. dissolved oxygen in potable water can destroy the protective coat and produced of oxidant ions but its insoluble forms. eq.25 shows reaction between polyamine and oxygen and the reaction gives h2o2 which further convert to hydroxide ion or radical oxygen in the water solution. the nitro compound x-no2 is analysis to xand no��. amide (–conh2) is feeble base have a lone pair of electrons on the nitrogen atom. after exposed to water solution, the amide linkages are broken. the long chains which break and can eventually end up with the original monomers. this mechanism can be represented by the following equations: x conh2 +hocl x-concl + h�o … (26) x – cohn-x +h�o xco2h + x-nh2 … (27) x conh2 + 4h+ xch2nh2 + h�o … (28) 2x conh2+ cl x-cocl + x-nh2 … (29) x conh2 +nacl x-cona + hcl + h+ … (30) x-conh2 + o2 x-coonh + oh … (31) the amide is hydrolysis in water and produces amine (weak base) and carbolic acid (weak acid). these products are reacts and contribute to accelerate the corrosion rates. 5. conclusions through the preceding discussion we can conclude the following points: 1. polyamine curing epoxy is more resistance to water corrosion compared to polyamide curing epoxy and have high impedance values. 2. eis tests of the two coatings show large change in impedance due to surface adsorption of water; this means that corrosion process appears to be initiated after test began directly. 3. surfaces of specimens analyzed after the test revealed that the model a has blistering while model b specimens surface shows blisters and pitting. 4. the protection rate of epoxy coats is inversely proportional with coats porosities. the porosity of polyamide epoxy coats larger than polyamine epoxy coats, so it’s less corrosion protection rate. pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com haider hadi jasim al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 9099 (2017) 98 5. the mechanism ofthe coatingsdegradation depends on type and percent of impurities contents by water and coating compositions. acknowledgement the author would like to thanks staff at chem. eng. dept. of tehran-2 university of iran for helps to achieve the eis test. also the author expresses thanks to stuff at chemical eng. dep. of basrah university for helps and support during works. 6. references [1] avery r., lamb s., powland c., tuthilla.,“stainless steel for potable water treatment plant”, nidi technical serious,no.10089, (1999). [2] stainless steel in drinking water supply, report of international stainless steel forum (issf), 2014. http://www.worldstainless.org/. [3] leidheiser, h. jr., “corrosion control by coatings”, science press, princeton edition, nj, usa, 143-170, (1979). [4] tato w. and landoltd., “electrochemical determination of the porosity of single and duplex pvd coatings of titanium and titanium nitride on brass”, journal of the electrochemical society, 45 (12), 4173-4181, (1998). [5] ramírez d., vera r., gomez h. and conajahua c., “evaluation of protecting properties of epoxy coating on navy steel by electrochemical impedance spectroscopy”, j. chil. chem. soc. 50 (2), 489-494, (2005). [6] mathiesen t. and frantsen j. e. “unusual corrosion failure of stainless steel in low chlorine water”, corrosion 2008, paper no. 8174, new orleans, usa, (2008). [7] havn t., norway z. a. ,“use of 316l in water systems offshore, possibilities and limitations”, report of american water works association (pncwa), 7-th international conference 2009, utah, usa. (2009). [8] francis r. a., mattioli g. and smith s., “relining of the potable water tanks for strength and corrosion resistance”, australian corrosion association corrosion prevention 2010 conference, paper no. 053, 1-10, (2010). [9] michael l. doolittle, “a comparison of ultra-long-life coating systems for water storage tanks”, journal of protective coating and lining (jpcl) 1, 7-12, (2011). [10] duraisamy r., pownsamy k. and asgedom g., “chemical degradation of epoxypolyamide primer by electrochemical impedance spectroscopy”, international scholarly research network (isrn) corrosion2012, 1-10, (2012). [11] sara a., reza p., mohammad h. m., seyed m. z. and seyed a. s., “beeswax-colophony blend: a novel green organic coating for protection of steel drinking water storage tanks”, metals 2015, 5, 1645-1664, (2015). [12] grade-316-316l1 stainless steels, report of north american stainless co. ,usa, 2010. [13] olivier m. and poelman m. ,“use of electrochemical impedance spectroscopy (eis) for the evaluation of electro-coating performance”, recent researches in corrosion evaluation and protection, edited by prof. reza shojarazavi , intech publisher, 1-26, (2012). [14] chena y.m., yubg.p. and huang j. h., “comparison of electrochemical porosity test methods for tin-coated stainless steel”, surface and coatings technology150, 309– 318, (2002). [15] harkonen e., dıaz b., swiatowska j., maurice v., seyeux a., vehkamaki m., sajavaara t., fenker m., marcus p. and ritalaa m., “corrosion protection of steel with oxide nano-laminates grown by atomic layer deposition, j. of the electrochemical society 158, 11, (2011). pdf created with pdffactory trial version www.pdffactory.com http://www.worldstainless.org/ http://www.pdffactory.com http://www.pdffactory.com )2017( 90-99 صفحة ،2العدد ،13المجلد الھندسیة الخوارزمي جلةم حیدر ھادي جاسم 99 الكھروكیمیائیة الممانعة باستخدام طریقةخزانات میاه الشرب االیبوكسي لطالء أداء یموقت طیفیةال حیدر ھادي جاسم ةجامعة البصر /كلیة الھندسة /قسم الھندسة الكیمیائیة raidhani73@yahoo.com: البرید االلكتروني الخالصة ن من ان مختلفانوعھناك . ومناقشتھا خزانات المیاه الصالحة للشربفي طالء ستخدم المطالء االیبوكسي لتآكل الآلیات تحقیق ،لبحثا االھدف من ھذ تم المحتوي على ایبوكسي البولي امید penguard hb و البولي أمینایبوكسي تحتوي على tankguard 412: ھما جوتنلشركة طالء االیبوكسي أظھرت النتائج . eisاالیبوكسي باستخدام طریقة اتطالءلتم تحدید المسامیة و. ) eis(الكھروكیمیائیة الطیفیة الممانعة باستخدام طریقة تھاودرس ھااختبار لكن الطالء المحتوي على . ا في المیاه الصالحة للشرب من مدینة البصرة مواختبارھا معند تطبیقھ ممتاز أداءاظھرا نئیالطالكال تحصل علیھا أن سالم بین فحص المجھري بعد االختبارال. قیمة اعلى من الممانعة أیضا وامتلكمادة البولي أمید الطالء الذي یحتوي مقاومة للتآكل مقارنة مع األكألرالبولیامین ھو على وتجاویف اتنقرظھر امادة البولي أمید المطلیة بطالء وحبینما السط على السطحبثور وحبیبات اظھرامین البولیاالیبوكسي السطح المطلي بطالء أن .السطح pdf created with pdffactory trial version www.pdffactory.com mailto:raidhani73@yahoo.com http://www.pdffactory.com http://www.pdffactory.com كفاح ،سلمان،مثنى 33 33 al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 3347 (2013) effect of solid particle properties on heat transfer and pressure drop in packed duct kifah h. hilal salman h. omran muthanna l. abdulla department of mechanical/ institute of technology baghdad (received 3 october 2013; accepted 30 april 2013) abstract this work examines numerically the effects of particle size, particle thermal conductivity and inlet velocity of forced convection heat transfer in uniformly heated packed duct. four packing material (aluminum, alumina, glass and nylon) with range of thermal conductivity (from200 w/m.k for aluminum to 0.23 w/m.k for nylon), four particle diameters (1, 3, 5 and 7 cm), inlet velocity ( 0.07, 0.19 and 0.32 m/s) and constant heat flux ( 1000, 2000 and 3000 w/ m 2) were investigated. results showed that heat transfer (average nusselt number nuav) increased with increasing packing conductivity; inlet velocity and heat flux, but decreased with increasing particle size.also, aluminum average nusselt number is about (0.85,2.2 and 3.1 times) than alumina, glass and nylon respectively. from optimization between heat transfer and pressure drop through packed duct, it is found thatfinest ratio (nuav / δp) equal to (19.12) at (dp = 7 cm, inlet velocity = 0.07 m/ s and 3000 w/m2 heat flux) with aluminum as packing material. keywords: sphere particle, packed duct, heat transfer. 1. introduction packed beds used in many applications in the industry ranging from heat and phase exchangers to heterogeneous catalytic reactors. packedbed equipment often consist of a tubular shell filled with solid pellets or particles such as conductive metal pellets in heat exchangers, catalytic porous media in catalytic reactors or, in the case of phase exchangers, plastic or ceramic packing material is used [1]. heat transfer and flow structure in a packed bed are influenced by many parameterssuch as working fluid velocity, particle size, particle shape, particle density and thermo physical properties of particle and working fluid. most of studies in packed bed investigated the effect of one or more of these parameters. li et al. [2] investigated experimentally the variation of particle shape on frictional pressure drops of fluid flow in porous beds packed with non – spherical particles. the beds are 635 mm tall and 90 mm in diameter and packed with glass spheres 1.5 / 3 / 6 mm diameter, glass hollow spheres 6*1 mm (ball diameter * hole diameter), stainless steel hollow spheres 6*3 mm, stainless steel cylinder 3*3 mm(diameter *length) and stainless steel cylinder 3*6 mm. it was found that the pressure drops in the packed beds with hollow spheres and cylindrical particles are much higher than the predications of the ergun equation if the diameters of the spheres and cylinders are employed in the equation. thomeo et al. [3] conducted the influence of tube to particle diameter ratio and air mass flux on the heat transfer inpacked bed of glass beads, cooledby the wall through which air percolated. tube – to – particle diameter ratios (d/dp) ranged from 1.8 to 55, while the air mass flux ranged from 0.204 to 2.422kg/ m2.s. the outlet bed temperature (tl) was measured by a brass ring – shaped sensor and by aligned thermocouples. the shape and average value of the entrance radial temperature profile depend on the particle size and fluid flow rate. kifah h. hilal al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 3347 (2013) 34 also, the effect of prandtle number of a medium on natural convection heat transfer across a horizontal layer was measured by [4] using stainless steel particles of diameters 1.6,3.2 and4.8 mm, glass particles of diameters 2.5 and 6 mm, and lead particles of diameter 0.95 mm with silicon oil , water and mercury as working fluids.the bed height varied from 2.5 to 12 cm, the experimental data indicate that the prandtle number has a significant effect on the magnitude of the heat transfer across a differentially heated fluid saturated porous layer, especially for low values of the prandtle number. in this paper, forced convection heat transfer of air in porous rectangular channel which consist of sphere bead is investigated numerically. the effects of fluid velocity, particle diameter, constant heat flux imposed on rectangular channel and type of porous media (thermal conductivity) on the convection heat transfer, pressure drop and heat transfer enhancement are investigated. 2. mathematical problem 2.1. system considered the system under analysis shown in fig.(1) is a rectangular duct (0.2m*0.2m) cross section and (1m) length that is completely filled randomly with a porous medium. the walls of the duct are maintained at constant heat flux. the porous medium has initially an uniform temperature (20oc). four packing material, having different thermal conductivity have been employed with air as the working fluid. table 1, particle thermal conductivity of the packing materials used in this paper [5]. material aluminum alumina glass nylon k (w/m.k) 200 40 1.01 0.23 the sphere pad inserts with different diameters and thermal conductivity taken from ref. [5] are shown in table (2). the other factors investigated are inlet air velocity which varies from (0.07 m/s) to (0.32 m/s), pad porosity (0.366 – 0.414) and duct constant heat flux varies at the range (1000 w/m2) to (3000 w/m2). under these conditions heat transfer occurred by forced convection from heated duct walls into air passes through packedduct. table 2, particle diameter, heat flux and inlet velocity investigated. inlet velocity (m/s) heat flux (w/m2 ) ks/kf porosity dp (m) material 0.07 1000 7843.1 0,938 0.03 aluminum 0.19 2000 0.409 0.05 0.32 3000 0.414 0.07 0.07 1000 1568.6 0.366 0.01 alumina 0.398 0.03 0.19 2000 0.409 0.05 0.32 3000 0.414 0.07 0,07 1000 39.6 0.366 0.01 glass 0.398 0.03 0.19 2000 0.409 0.05 0.32 3000 0.414 0.07 0.07 1000 9 0.366 0.01 nylon 0.398 0.03 0.19 2000 0.409 0.05 0.32 3000 0.414 0.07 kifah h. hilal al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 3347 (2013) 35 35 2.2. basic equations the flow field and temperature field are symmetrical above the centre line of the channel. themathematical analysis carried out under the following assumptions [7]: 1. the flow is steady, fully developed and velocity is function of “y” cooled only. 2. air and porous medium is in local thermodynamic equilibrium. 3. the permeability and porosity are functions of “y” coordinate only. 4. thermal dispersion of heat in the x – direction is negligible into the energy equation. 5. all physical properties of the air and solid packing are constant and they will be calculated at the inlet condition. the governing equations under the above assumptions are: a. momentum equation: = ( ) − ( ) − a( ) u …(1) this equation known as “darcy – forchhemer – brinkman momentum equation”, take into account the boundary effects and inertial forces of air through packed duct [7]. ε(y) = ε [1 + c exp ( ( −a))] …(2) where “c” and “d” are empirical constants, “a” is the half width of the duct, “dp” is the particle diameter and is the core porosity. the permeability of porous medium is [8]: k(y) = ε( ) ( ε( )) …(3) the parameter a(y) is called the forchheimer constant [7]: a(y) = . ( ) ( ) …(4) the boundary condition on velocity and pressure are: = 0 = 0 / = 0 = /2 …(5) = = b. continuity equation: = 0 …(6) c. energy equation: = …(7) with the boundary condition: = − at y = 0 = − at y = w …(8) = at x = 0 the effective thermal conductivity (ke) is divided into (kst) stagnant thermal conductivity and ( kd) thermal dispersion conductivity due to air flow through packed duct [5]. = + …(9) { 1− √1− + √ ∗[ ( ) ( ) ln − − ]} …(10) where = 1.25 [(1 − ( ) ] and = = 0.1 …(11) 3. numerical method a finite differences method with central differencing scheme shown in fig.(2) is used for the numerical solution of the problem, including a line – by – line triadiagonal matrix algorithm (tdma) method for solving the set of algebraic equation that is yielded from the initial guess of the velocity distribution and boundary conditions. momentum equation (1) is rewritten in a different form as: 0 = u i,j+1 u i,j (f1 +f2 u i,j) + u i,j-1 +f3 …(12) where: f1 = 2+ ( ) ( ) (∆ ) …(13) f2 = ( ) ( ) (∆ ) …(14) f3 =( ) ( ) (∆ ) …(15) kifah h. hilal al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 3347 (2013) 36 36 and energy equation (7) is rewritten as: 0 = t i,j +1 + t i, j -1 + (f4 – 2) ti,j + t i-1, j …(16) where: f4 = (∆ ) (∆ ) …(17) the momentum equation is solved to determine the velocity profile, then, the velocity field is combined with the energy equation to determine the temperature profile. after knowing the temperature distribution inside the duct bulk temperature (tb) can be found from: ( ) = ∫ ∫ …(18) fig. 1. physical model fig. 2. coordinate system and grid distribution. the convection heat transfer coefficient (h) in packed duct can be found from: h = …(19) nusselt number (nu) can be expressed according to thermal conductivity of the fluid and equivalent diameter of the duct as: nu =ℎ ...(20) reynolds number ( ∈) is based on particle diameter and porosity as: ∈ = ( ) …(21) also, pressure drop (δp /l) through packed duct for reynolds number higher than (10) can be found as [ 9]: ∆ = 1.75 ( ) …(22) 4. results and discussion the present analysis is confined to studying the influence of pad conductivity, particle diameter, inlet velocity and heat flux on forced convection in porous duct. table (1) shows the range of the variables used in the numerical calculation. a total of (144) runs were conducted kifah h. hilal al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 3347 (2013) 37 37 to cover four packed bed material (aluminum, alumina, glass and nylon) with four particles diameter ( 1,3,5 and 7 cm). the range of heat flux used varied from (1000 w/ m2) to (3000 w/ m2) and inlet air velocity varied from (0.07 to 0.32 m/s). the velocity profile, pressure drop, temperature profile, variation of air temperature along the duct, local heat transfer coefficient, local nusselt number and average nusselt number were investigated in this paper with the parameters illustrated in table (1). 4.1. velocity profile fig.(3) shows the axial velocity profile for (0.07, 0.19 and 0.32 m/s), the variation in velocity occur near the duct wall due to the no homogeneity in porosity and wall channeling effect, while the velocity is constant at the duct core. it can see the channeling increases with decreases particle diameter. 4.2. pressure drop fig.(4) shows the pressure gradients of air flow through beds packed by sphere particles with diameter (1,2,3,5 and 7 cm). it is found that the pressure drop decreased with increasing particle diameter and the particle conductivity have no effect on pressure drop through the bed. 4.3. temperature profile in general, the variation of temperature distributions across the duct affected by heat flux, reynolds number, particle diameter and particle conductivity. the general shape of all curves obtained, shown that the high porosity near the wall leading to enhancement of heat transfer from heated duct surface to air which passes faster in this region due to channeling effect and the air temperature gradually decrease going away from the duct wall. figs.(5),(6),(7) and (8)represent similar plots of axial temperature profiles of air for (aluminum, alumina, glass and nylon particle), (dp = 3,5and 7 cm), ( inlet air velocity = 0.32 m/s) and ( heat flux = 1000 w/ m2).the temperatures are plotted as a function of axial position, at the entrance of duct the variation of temperature taken approximately (4 cm) from the wall while the variation taken all width at the duct exit. fig.(9) illustrate temperature distribution for four type of packing at 0.32 m/s inlet velocity, 1000 w/m2 heat flux and 3 cm particle diameter. it is seen that aluminum and alumina plots decrease gradually from duct surface into duct centerline. the variation in glass and nylon plots taken place at small region near the surface, not extend into bulk region. the mechanisms of heat transfer in packed bed are convective heat transfer from duct wall to the air, convective heat transfer from the packing particles to the air and conduction from the wall to the particles. in aluminum and alumina plots which have high conductivity enhance conduction from wall to the particles and increased particle temperature then increased convective heat transfer from packing particles to the air. 4.4. local heat transfer coefficient fig. (12) shows local heat transfer coefficient in packed duct for aluminum, alumina, glass and nylon packing. it is concluded that for a constant thermal conductivity an increase in particle size yields a decrease in porosity and contact area between pad and air then decrease in local heat transfer coefficient. any increasing in inlet velocity yields to increase turbulence and decrease thermal boundary layer thickness which cause high local heat transfer coefficient for a constant particle size, packing conductivity and heat flux, this result is plotted in fig.(13) for 4 – packing. fig.(14) illustrate the effect of heat flux on local heat transfer coefficient. it is seen that (h x) increase as heat flux increase, due to high temperature difference between duct wall temperature and air bulk temperature. 4.5. local wall to fluid nusselt number aluminum, alumina, glass and nylon packing evaluated by eq.(20) using equivalent diameter of duct and air thermal conductivity are drawn in fig.(15) and fig.(16) which show that the plots have similar trend of (h x), increased at (5.1, 4,3, 2.2 and 1.4 percent) with increasing heat flux and at (36.7,38.8,44.6 and 45.7 percent) inlet air velocity but (nu x) increased at (12.8,12.6,8.3 and 5.8 percent) with decreasing particle size. for (aluminum, alumina, glass and nylon) packing respectively the variation of (nu x) with duct length for 4 – packing are presented for (heat flux = 1000 w/ m2, inlet velocity = 0.32 m/s and particle diameter =3 cm) in fig. (17). it show the highest (nu x) for aluminum packing due to high thermal conductivity which results in high contact kifah h. hilal al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 3347 (2013) 38 38 conduction then (nu x) of alumina, glass and nylon respectively. 4.6. average nusselt number versus particle reynolds number the relationship between average nusselt (nu av) and particle reynolds number (re ε ) is plotted in fig.(18) for 4–packing materials used in this paper. the relationship is correlated in the form: nu av= c (re ε)m … (23) table (3) summarizes the correlation constants (c) and (m) for all the packing materials. in general, the exponent (m) tends to decrease with increasing thermal conductivity of the packing material but the factor (c) increase with increasing it. table 3, constant (m &c) for eq.(23). packing material c m aluminum 87.54 0.0838 alumina 68.692 0.0951 glass 29.08 0.1339 nylon 17.949 0.1473 a comparisons of final results of average nusselt number for 4–packing material are presented in table (4). it is observed that aluminum (nuav) is about (0.85), (2.2) and (3.1) times approximately higher than alumina, glass and nylon respectively 4.7. optimization heat transfer and pressure drop the results show that heat transfer increased as particle diameter decreased and inlet velocity increased which proceeded high pressure drop through the packed duct. a good design of packed bed must have an optimization between pressure drop and heat transfer. for that (nu av / δp) parameter is used to analyze the results of 4– packing involved in this paper. it is shown that the finest ratio obtained is (19.12) at (dp = 7cm, inlet velocity = 0.07m/s and heat flux = 3000 w/m2), (18.96) and (18.5) at the same variable but (heat flux = 2000 and 1000 w/m2) respectively when using aluminum as packing material. kifah h. hilal al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 3347 (2013) 39 39 table 4, comparison between average nusselt number for 4 – packing material. inlet velocity vel m/s pressure pa/m nu av dp (cm) nylon glass alumina aluminum 0.32 1619.45 64.276 96.111 171.466 199.948 1 0.32 397.43 61.745 90.663 157.917 183.1598 2 0.32 216.736 60.937 88.962 153.806 178.1 5 0.32 148.028 60.627 88.292 162.713 176.063 7 0.32 1619.45 951.64 97.73 177.194 207.906 1 0.32 397.43 62.364 92.0927 158.337 189.75 3 0.32 216.736 61.539 90.333 156.55 184.31 5 0.32 148.028 61.217 89.629 164.107 182.075 7 0.32 1619.45 65.1804 98.292 179.23 210.776 1 0.32 397.43 62.57 92.582 159.93 192.119 4 0.32 216.736 61.742 90.802 158.095 186.533 5 0.32 148.028 61.416 90.087 156.2 184.217 7 0.19 583.004 53.115 79.255 144.133 169.86 1 0.19 143.075 51.06 74.738 132.117 154.62 3 0.19 78.025 50.398 73.32 128.488 150.055 5 0.19 53.29 50.131 72.737 126.946 148.092 7 0.19 583.004 53.604 80.428 148.398 175.888 1 0.19 143.075 51.508 75.77 135.66 159.568 3 0.19 78.025 50.833 74.311 131.83 154.69 5 0.19 53.29 50.55 73.703 130.181 152.58 7 0.19 583.004 53.769 80.831 149.909 178.049 1 0.19 143.075 51.66 76.122 136.91 161.33 3 0.19 78.025 50.98 74.649 133.005 156.384 5 0.19 53.29 50.703 74.033 131.317 154.173 7 kifah h. hilal al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 3347 (2013) 40 40 0.07 64.778 35.093 53.649 106.313 128.468 1 0.07 15.89 33.705 50.316 96.077 115.324 3 0.07 8.669 33.249 49.272 93 111.382 5 0.07 5.9211 33.049 48.8035 91.591 109.57 7 0.07 64.778 35.3344 54.252 108.82 132.192 1 0.07 15.89 33.926 50.842 98.113 118.296 3 0.07 8.669 33.46 49.774 94.904 114.147 5 0.07 5.9211 33.26 49.294 93.128 112.239 7 0.07 64.778 35.416 54.458 109.707 133.517 1 0.07 15.89 34.0008 51.022 98.826 119.347 3 0.07 8.669 33.536 49.946 98.569 115.153 5 0.07 5.9211 33.3319 49.461 94.069 113.192 7 fig. 3. velocity profile in packed duct. kifah h. hilal al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 3347 (2013) 41 41 fig. 4. pressure drop versus particle reynolds number. fig . 5. temperature profile versus duct width for various particle sizes for aluminum packing. fig. 6. temperature profile versus duct width for alumina packing. kifah h. hilal al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 3347 (2013) 42 42 fig. 7.temperature profile versus duct width for glass packing. fig. 8.temperature profile versus duct width for nylon packing. fig. 9.temperature profile versus duct width for 4packing material width for different heat flux. kifah h. hilal al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 3347 (2013) 43 43 fig. 10. temperature profile versus duct. fig. 11.temperature profile versus duct width for different inlet velocity. kifah h. hilal al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 3347 (2013) 44 44 fig. 12. local heat transfer coefficient versusparticle size for 4-packing. fig. 13. local heat transfer coefficient versusinlet velocity for 4-packing. fig. 14. local heat transfer coefficient versus heat flux for 4-packing. fig. 15. local nusselt number versus particle size for 4-packing. kifah h. hilal al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 3347 (2013) 45 45 fig. 16. local nusselt number versus inlet velocity for 4-packin. fig. 17. local nusselt number versus ductwidth for 4-packing material. fig. 18. correlation of nusselt number and particle reynolds number. 5. conclusions in this paper, various effect on forced convection heat transfer and pressure drop in packed duct are investigated numerically using 4– packing material (aluminum, alumina, glass and nylon). it is shown that: 1. average nusselt number (nu av) increased with increasing packing conductivity, aluminum (nu av) is higher about (0.85, 2.2 and 3.1 times) than alumina, glass and nylon respectively. 2. (nu av) increased with decreasing particle size, but this result high pressure drop. for good design, it is found that the finest ratio (nu av / δp) is (19.12) when aluminum is packing material, particle diameter = 7cm, inlet velocity = 0.07 m/s and heat flux = 3000w/m2. 3. (nu av) increased with increasing inlet air velocity and heat flux supplied into duct walls. 4. many correlation are obtained for (nu av) as a function of (re ε ) which included the effects of particle size, velocity, heat flux and packing conductivity. nomenclature a duct cross – section area m2 a(y) forchheimer constant - cp air specific heat at constant pressure kj/kg.k dp particle diameter cm deq duct equivalent diameter m dp/dx pressure gradient pa/m hx local heat transfer coefficient w/m2.k kifah h. hilal al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 3347 (2013) 46 46 i index for axial direction - j index for vertical direction - k(y) permeability of porous medium - kf fluid thermal conductivity w/m.k ks particle thermal conductivity w/m.k ke effective thermal conductivity w/m.k kst stagnant thermal conductivity w/m.k kd thermal dispersion conductivity w/m.k l duct length m po pressure at exit duct pa q heat absorbed by air w qw heat flux w t temperature oc ti inlet temperature oc tb air bulk temperature oc ts surface duct temperature oc ui velocity at duct entrance section m/s w duct width m y index vertical length (width) m reε particle reynolds number - nux local nusselt number - nuav average nusselt number - ped particle peclet number - ρ density kg/m3 µ dynamic viscosity kg/m.s γ kinematic viscosity m2/s ε porosity - ε(y) porosity with respect to vertical location - 6. references [1] petrov a.s,” momentum and heat transfer in a packed bed”, mae / ceng221a,2006. [2] li l. and ma w., “ experimental study on the effective particle diameter of a packed bed [3] with non – spherical particles”, transp. porous med., volume 89, page 35 – 48, 2011. [4] thomeo j., rouiller c. and freire j.,” experimental analysis of heat transfer in packed beds with air flow”, ind. eng. chem. res.,volume 43, page 4140 – 4148, 2004. [5] jonson t. and catton i.,” prandtle number dependence of natural convection in porous media”, journal of heat transfer, volume 109, page 371 – 377, 1987. [6] naser k., ramadhyani s. and vistanta r.,” an experimental investigation on forced convection heat transfer from cylinder embeded in a packed bed”, journal of heat transfer, volume 116, page 73 – 79, 1994. [7] chandiasekhara b. and radha n.,” effect of variable porosity on laminar convection in a uniformly heated vertical porous channel”, wärme – und stoffübertragung, volume 23, page 371 – 377, 1988. [8] hong j., yamada y. and tien c., “ effects on non – daracian and non uniform porosity on vertical plate natural convection in porous media”, transactions of the asme, vol. 109, pp 356 – 376, 1987. [9] hwang g. and chao c., “ heat transfer measurement and analysis for sintered porous channels”, transactions of the asme, j. heat transfer, volume 116, pp. 456 – 464, 1994. [10] vafai k.,” handbook of porous media”, 2nd edition by taylor &franice group, 2005. )2013( 3347 ، صفحة2، العدد9مجلة الخوارزمي الھندسیة المجلد كفاح حامد ھالل 47 47 تأثیر خصائص الحشوة الكرویة على انتقال الحرارة وفقدان الضغط في مجرى مسامي عمران مثنى لطیف عبد اهللا كفاح حامد ھالل سلمان حسین بغداد -تكنولوجیا المعھد/ قسم المیكانیك الخالصة ال الحرارة اجریت في ھذا البحث دراسة عددیة لتأثیر قطر الجزیئة المكونة للحشوة المسامیة والموصلیة الحراریة لھا وسرعة الھواء الداخل على انتق وبمدى ) االلمنیوم، االلومینا، الزجاج والنایلون( الحشوات مصنوعة من أربعة أنواع من . بالحمل القسري خالل مجرى مسامي مسخن بفیض حراري ثابت ) m/s 0.32 ,0.19 ,0.07( وسرعة ) cm 1,3,5,7(وبقطر جزیئة ) للنایلون 0.23w/m.kلاللمنیوم الى 200w/m.k(موصلیة حراریة یتراوح بین تزداد بزیادة ) nuavمعدل رقم نسلت ( لقد بینت النتائج ان انتقال الحرارة . تم اختبارھا) w/m2 1000,2000,3000( وبفیض حراري ثابت مقداره لحشوة االلمنیوم ) nuav(معدل رقم نسلت . الموصلیة الحراریة للحشوة المسامیة وسرعة الھواء الداخل والفیض الحراري، ولكن یقل بزیادة قطر الجزیئة من المفاضلة بین انتقال الحرارة وفقدان الضغط خالل الحشوة المسامیة، . على التوالي) االلومینا، الزجاج والنایلون( من ) مرة 0.85 ,2.2 ,3.1( أعلى ب ، واستخدام االلمنیوم كحشوة )w/m2 3000وفیض حراري dp = 7cm، u = 0.07 m/s( عند ) 19.12( تساوي (nuav / δp )نجد أن أفضل نسبة . مسامیة داخل المجرى سليمان مرتضى وعلي خليل al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 8, no.4, pp 1-8 (2012) speech compression using multecirculerletet transform sulaiman murtadha ali. k. ibrahim department of electrical engineering/university of baghdad (received 20 march 2011; accepted 14 may 2012) abstract compressing the speech reduces the data storage requirements, leading to reducing the time of transmitting the digitized speech over long-haul links like internet. to obtain best performance in speech compression, wavelet transforms require filters that combine a number of desirable properties, such as orthogonality and symmetry.the mct bases functions are derived from ghm bases function using 2d linear convolution .the fast computation algorithm methods introduced here added desirable features to the current transform. we further assess the performance of the mct in speech compression application. this paper discusses the effect of using dwt and mct (one and two dimension) on speech compression. dwt and mct performances in terms of compression ratio (cr), mean square error (mse) and peak signal to noise ratio (psnr) are assessed. computer simulation results indicate that the two dimensions mct offer a better compression ratio, mse and psnr than dwt. keywords: sound, speech compression, mct, dwt. 1. introduction data compression is the process of converting an input data stream (the source stream or the original raw data) to a data stream with a smaller size (the output, the bit stream, or the compressed stream). a stream is either a file or a buffer in memory. data compression is popular for two reasons: (1) people like to accumulate data and hate to throw any data away. no matter how big a storage device one has, sooner or later it is going to overflow. data compression seems useful because it delays this inevitability. (2) people hate to wait a long time for data transfers. when sitting at the computer, waiting for a web page to come in or for a file to download, anything longer than a few seconds is a long time to wait [1]. speech coding is a lossy type of coding, which means that the output signal does not exactly sound like the input. the input and the output signal could be distinguished to be different. coding of audio however, is a different kind of problem than speech coding. audiocodingtries tocodetheaudioin a perceptually lossless way. this means that even though the input and output signals are not mathematically equivalent, the sound at the output is the same as the input. this type of coding is used in applications for audio storage, broadcasting, and internet streaming [2]. speech compression plays an important role in teleconferencing, satellite communications and multimedia applications. however, it is more important to ensure that compression algorithm retains the intelligibility of the speech. the success of the compression scheme is based on the simplicity of the technology and efficiency of the algorithm used in the system. parametric coding techniques are commonly used methods for speech compression and its application [4]. this paper deals with speech compression of isolated spoken words. a flexible compression scheme that is based on mct decomposition is used in this work. this paper is organized as follows. section 2 gives a discussion of the discrete wavelet transforms. section 3 explains the data base used for the experiment.section 4 is devoted for computer simulation and results and section 5 concludes the paper. sulaiman murtadha al-khwarizmi engineering journal, vol. 8, no.4, pp 18 (2012) 2 2. discrete wavelet transform the signal is passed through a series of high pass filters to analyze the high frequencies, and it is passed through a series of low pass filters to analyze the low frequencies. the procedure starts with passing this signal (sequence) through a half band digital lowpass filter with impulse response h[n]. filtering a signal corresponds to the mathematical operation of convolution of the signal with the impulse response of the filter. the convolution operation in discrete time is defined as follows [4]: ]2[].[][ nkhnxkl n −= ∑ …(1) ]2[].[][ nkfnxkh n −= ∑ …(2) ][kl and ][kh are the outputs of the lowpass and highpass filters. 3. multicircularlet transform one famous multifilter bank is the ghm filter proposed by geronimo, hardian, and massopust [5]. the ghm basis offers a combination of orthogonality, symmetry, and compact support, which cannot be achieved by any scalar wavelet basis [6]. the ghm two scaling and wavelet functions satisfy the following two-scale dilation equations: ∑       − − =      k k kt kt h t t )2( )2( 2 )( )( 2 1 2 1 φ φ φ φ …(3) ∑       − − =      k k kt kt g t t )2( )2( 2 )( )( 2 1 2 1 φ φ ψ ψ …(4) where hk for ghm system is four scaling matrices h0, h1, h2, and h3.also, gk for ghm system are four wavelet matrices: g0, g1, g2, and g3. the individual coefficients values of these matrices are generated using the following procedure: 1. apply the 2-d linear convolution between the g’s & h’s . this can be achieved as follows: a) compute iii hha ⊗=1 b) compute iii ggb ⊗=1 where i= 0,1,2,3 2. now compute the 2-d convolution between the resultant of step 1 & the g’s & h’s. this can be done through the following way: a) compute iii haa ⊗= 12 b) compute iii gbb ⊗= 12 where i= 0,1,2,3 2. the linear convolution process will be repeated several times. it was found that the optimal results were at the third step. this selection is based upon the evaluation of the application of the resultant coefficients in compression task. the proposed matrix coefficients a’s and b’s wear obtained by performing the following computations: a) compute iii haa ⊗= 2 b) compute iii gbb ⊗= 2 where i= 0,1,2,3 the new multifilter bases functions are denoted by a’s and b’s which are stated as , , , & , , , the results of the third convolution (basis functions) are: a) the a’s 2x2 matrices are: = 1.4561 1.4131− 1.0265 −0.9857 , = 1.6896 1.5814 1.4376 1.5450 = 0.0977 −0.09450 0 , = 1.0 − 005 ∗ 0.6250 00 0 b) the b’s 2x2 matrices are: = 0.0460 0.0343−0.0459 −0.0 342 , = 2.7696 −2.4406−2.4142 2.7225 = 1.6610 −1.60661.6581 −1.6038 , = −0.0302 −0.03020.0052 0.0052 the results show that at the third convolution the number of zeros in the resultant matrix increased which gives matrices similar in construction to laurent matrix. due to the good characteristics of the transformed 1-d signal (speech) by the basis functions obtained from the third convolution, it will be adopted as the transform named “multicircularlet transform”. the ab multifilter bank coefficients are 2 by 2 matrices, and during the convolution step they must multiply vectors (instead of scalars). this means that multifilter banks needs 2 input rows. this transformation is called preprocessing. the sulaiman murtadha al-khwarizmi engineering journal, vol. 8, no.4, pp 18 (2012) 3 most obvious way to get two input rows from a given signal is to repeat the signal. two rows go into the multifilter bank. this procedure is called “repeated row” which introduces oversampling of the data by a factor of 2 [8]. for a given scalar input signal {xk} of length n (n is assumed to be a power of 2 and so is of even length), repeated row preprocessing of this signal is by repeating the input stream with the same stream multiplied by a constant α. so the input length-2 vector are formed from the original as: …(5) where k=0,1,2,…,n-1 here is constant, and from the preprocessing scheme of the ghm multifilter bank , is equal to (1 √2 ). it is found that this factor is very suitable for preprocessing the application of the proposed transform. after the multifilter bank reconstruction (synthesis) step a postfiltering is applied. if the preprocessing step, represented by a matrix multiplication, = …(6) where p is 2nxn, x is nx1, and is 2nx1, then in detail                 =                 =                                 mmmo l l l l 1 1,0 0 1,0 1 0,0 0 0,0 1 1 0 0 3 2 1 0 00 010 00 001 v v v v x x x x x x x x α α α α …(7) for computing discrete multicircularlet transform, the transformation matrix can be written as follows:                             = 1032 3210 3210 3210 1032 3210 3210 000000 000000 000000 0000 000000 000000 000000 bbbb bbbb bbbb bbbb aaaa aaaa aaaa w l l mmmmlmmmmmm l lmm l mmmmlmmmmmm l l …(8) where , are the impulse responses of the multifilter bank. 4. proposed compression algorithem 4.1. implementing wavelet and multicirculertlet transform the following steps will be followed in the implementation of this algorithm: 1. record and read the input speech in sampled and digitized form. in this step the input speech will be shown as a one dimension array stored in specified vector. 2. apply dwt, save the coefficients and write them as an audio file format called wav format. 3. apply mct; 1d & 2d mct for an input speech are used. at first 1d mct is applied. for this purpose, each speech after sampling will be resized to the power of two. then by using a different program, 2d mct will be applied. in 2d mct program, the speech samples are divided into different levels, each level contains 2 samples. write output files as a stream in the desired format. 4.2. applying multicirculerletlet transform mct contains the following steps: a) use hamming window and different levels by changing ns. b) it is possible to apply 1d or 2d mct. b.1) for applying 1d mct: b.1.i) compute the length of the speech, the number of total samples contained. b.1.ii) if the length is to power of two, apply mcts directly, save the coefficients and write them as a wav file. b.1.iii) if the length is not to power of two, refer to the original file, append silence or near zero samples to get a power of two speech samples. compute the mct for the entire speech, save the coefficients and write them as a wav file. b.2) for applying 2d mct: b.2.i) it doesn’t matter that the length of the speech is to the power of two or not. starting n = 2 (each frame equals 4 samples) and increasing n (maximum n = 6, depending on the original speech bit rate) achieve the desired compressed speech, good compression and good quality. b.2.ii) framing is used to cut the long-time speech to the short-time speech signal in order         kx kx α sulaiman murtadha al-khwarizmi engineering journal, vol. 8, no.4, pp 18 (2012) 4 to compute 2d mct. each frame contains 2 samples, so the number of columns is equal to 2 and the number of rows is the integer of dividing the total number of speech samples into 2 . b.2.iii) compute the mct for each row, then column wise on the result, finally cascade the rows, save the coefficients and write them as a wav file. 5. experiment results after applying the transforms to speeches, the compressed and uncompressed speeches will be written as a stream file in the form of wav for playing them on any software like windows media player or use them on the internet as stream media or even more complicated systems like telephone switches. also, it is possible to write the results in another form using au extension. but wav extension is preferred more than au. the test material contains seven speech samples stored as files, the format of these files are wave format. each file has different size and different number of samples. the type of the digital speech is pulse code modulation (pcm) and the tested speech samples are in the bit rate of 64, 256 and 3072 kbps. the properties of the tested speech samples are presented in tables (1, 2, 3, 4, 5, 6, and 7) and fig. (1). table 1, properties of tested speech samples. file name file size (byte) total samples be 2251016 562743 ru 4155904 1038965 r01 5266700 1316664 r02 5931500 1482864 r03 7886092 1971512 he 4815572 1203882 table 2, performance measures of speech signals. table 3, compression performance results using haar dwt. file name input size output size cr% cf compression gain be 2251016 281416 12.502 7.999 91.303 ru 4155904 479528 11.538 8.667 94.785 r01 5266700 588376 11.172 8.951 95.188 r02 5931500 641476 10.815 9.247 96.598 r03 7886092 785800 9.964 10.036 100.155 he 4815572 551986 11.463 8.724 96.072 average 11.242 8.937 95.120 signal psnr mse wavelet 2d mct wavelet 2d mct be 49.8350 52.9273 0.6084 0.3314 ru 49.6102 52.1699 0.6671 0.3945 r01 51.9419 55.1144 0.3841 0.2003 r02 51.8094 54.3706 0.4113 0.2377 r03 49.8011 52.6932 0.6354 0.3498 he 50.3298 53.1462 0.5676 0.3151 sulaiman murtadha al-khwarizmi engineering journal, vol. 8, no.4, pp 18 (2012) 5 table 4, compression performance using 1d mct. z input size output size cr% cf compression gain be 2251016 652788 29.000 3.448 53.761 ru 4155904 1127974 27.141 3.684 56.637 r01 5266700 1299708 24.678 4.052 60.769 r02 5931500 1492908 25.169 3.973 59.913 r03 7886092 1971556 25.000 4.000 60.205 he 4815572 1273926 26.454 3.780 57.750 average 26.240 3.823 58.241 table 5, compression performance using 2d mct n = 1. file name input size output size cr% cf compression gain be 2251016 584788 25.979 3.849 58.538 ru 4155904 1027974 24.735 4.043 60.668 r01 5266700 1259708 23.918 4.181 62.127 r02 5931500 1372908 23.146 4.320 63.552 r03 7886092 1771556 22.464 4.452 64.851 he 4815572 1173926 24.378 4.102 61.301 average 24.103 4.158 61.887 table 6, compression performance using 2d mct n = 2. file name input size output size cr% cf compression gain be 2251016 273416 12.146 8.233 91.555 ru 4155904 459528 11.057 9.044 95.635 r01 5266700 528376 10.032 9.968 99.860 r02 5931500 561476 9.466 10.564 102.383 r03 7886092 685800 8.696 11.499 106.066 he 4815572 501986 10.424 9.593 98.196 average 10.304 9.817 99.197 sulaiman murtadha al-khwarizmi engineering journal, vol. 8, no.4, pp 18 (2012) 6 table 7, compression performance using 2d mct n = 3. file name input size output size cr% cf compression gain be 2251016 133416 5.927 16.872 122.717 ru 4155904 279528 6.726 14.868 117.224 r01 5266700 318376 6.045 16.542 121.860 r02 5931500 331476 5.588 17.894 125.271 r03 7886092 385800 4.892 20.441 131.050 he 4815572 301986 6.271 15.946 120.266 average 5.908 17.094 123.284 (a) mean square error (mse) (b) peak signal to noise ratio (psnr) fig. 1. performance measures of speech signals. it is shown that 1d has the maximum compression ratio percentage. the best compression ratio is in the case of 2d mct with maximum number of levels, n equal 3. wavelet mct 0 0.2 0.4 0.6 0.8 m ea n sq ua re e rr or (d b) speech samples be ru r01 r02 r03 he wavelet mct 46 48 50 52 54 56 pe ak s ig na l t o n oi se r at io (d b) speech samples be ru r01 r02 r03 he sulaiman murtadha al-khwarizmi engineering journal, vol. 8, no.4, pp 18 (2012) 7 6. conclusions the haar wavelet transform is the simplest and the fastest one to implement. however, because of its discontinuity, it is not optimal to simulate a continuous signal. based on our experiments. haar wavelet obtained the worst compression result, which proves the above statement. db4 found the first continuous orthogonal compactly supported wavelet. note that this family of wavelets is not symmetric. the advantage of symmetry is that the corresponding wavelet transform can be implemented using a mirror boundary condition, which reduces boundary artifacts. the mct is a symmetrical transform and easy to implement. the mct based compression software designed reaches a signal of noise ratio of 55.114db and cr equal to 20.4. the proposed method could be classified in the field of symmetrical compression. this case occurs when the compression and decompression use basically the same algorithm but work in opposite directions. 7. references [1] d. salomon, 2007 “data compression, the complete reference”, fourth edition, contributions by, springer-verlag london. [2] “law bit-rate speech coders for multimedia communication,” r.v. cox and p. krmn, leee [3] communications magazine, pages 34-40, 1996 http://www.bell-labs.com [4] shijo m joseph, firoz sha a and babu anto p “speech compression: a comparative study between discreet wavelet and wavelet packet decomposition” international journal of computer and network security vol 2. no7 2010. [5] g. strange and t. nguyen, 1996 “wavelets and filter banks”, wellesley, wellesleycambridge. [6] geronimo, j., hardian,d.& massopust, p. “ fractal function and wavelet expansion based on several functions”, j. approx. theory, vol. 78, pp. 373-401, 1994. [7] burrus, c.s., goperath, r.a., and gue, h., “introduction to wavelet and wavelet transforms”, a primer upper saddle, nj(u.s.a.), prantice hall, inc., 1998. [8] strela, v. & walden, a.t. “ orthogonal and biorthogonal multiwavelets for signal denoising and image compression”, proc. spie, 3391: 96-107, 1998. [9] shi zhong and vladimir cherkassky, “image denoising using wavelet thresholding and model selection”, dept. of ece, univ. of texas at austin, 2001. http://www.bell-labs.com )2012( 18، صفحة 4، العدد8مجلة الخوارزمي الھندسیة المجلد سلیمان مرتضى 8 ضغط الكالم باستخدام تحویل الملتي سیكلرلیت علي خلیل ابراھیم سلیمان مرتضى عباس جامعة بغداد/ كلیة الھندسة/ قسم الھندسة الكھربائیة الخالصة ،ومن اجل الحصول على اكفأ اداء. زمن رسال الكالم الرقمي خالل ضغط االنترنیتضغط الكالم یقلل متطلبات خزن المعلومات مما یؤدي الى اختصار خوارزمیة الملتي سیكلر لیت المشتقة من دالة . استعملت خوارزمیة الویفلیت والتي تحتاج الى مرشحات ذات خصائص مرغوبة مثل التناظر والتعامد )ghm (یناقش ھذا . الخوارزمیة خوارزمیة الجدیدة في مجال ضغط الكالم وذلك للسرعة العالیة لھذهلذه اتم استعمال ھ. وتستعمل دالة الكونفلیوشن الخطیة ومعدل مربع الخطأ، ) cr( البحث تأثیر استخدام ھذه خوارزمیة وخوارزمیة الویفلیت في ھذا التطبیق وكفأءة االداء حسبت من حیث نسبھ الضغط )mse(، ونسبھ االشارة الى الضوضاء )psnr .( برامج الحاسبة التمثیلیة لھذا التي تؤثر ان خوارزمیة الملتي سیركلر لیت ذات البعدین اعطت افضل . النتائج 10 al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 110 (2014) improvement of microhardness and corrosion resistance of stainless steel by nanocomposite coating hamid s. mahdi* kareem neamah sallomi** hiba husam ismail*** *,**,*** department of automated manufacturing engineering / alkhwarzmi college of engineering/ university of baghdad * email: mahdih27@yahoo.com ** email: kareemsallomi@yahoo.com *** email: hibahusamismail@yahoo.com (received 22 june 2014; accepted 22 october 2014) abstract stainless steel (aisi 304) has good electrical and thermal conductivities, good corrosion resistance at ambient temperature, apart from these it is cheap and abundantly available; but has good mechanical properties such as hardness. to improve the hardness and corrosion resistance of stainless steel its surface can be modified by developing nanocomposite coatings applied on its surface. the main objective of this paper is to study effect of electrocodeposition method on microhardness and corrosion resistance of stainless steel, and to analyze effect of nanoparticles (al2o3, zro2 , and sic) on properties of composite coatings. in this paper employed electroco-deposition process to develop a composite coating with (ni) matrix and ceramic oxide particles: al2o3 (135nm), zro2 (40nm), and sic (80nm) as reinforcements. the coatings were developed with 10 g/l, and 20 g/l concentrations in bath, at four different current densities (0.5, 1, 2, 3 a/dm 2 ) using watts bath to study the effect of current density and particle concentration in bath, on structure and properties of the coatings developed. the surface morphology of nanocomposite coating was characterized by scanning electron microscopy (sem). the hardness of the nanocoating was carried out using digital vickers microhardness tester. the corrosion resistance property of nanocomposite coating was carried out in 3.5% nacl solution used open circuit potential (ocp) and potentialastic polarization. the results showed the nanocomposites coating have a smooth and compact surface and have higher hardness than the uncoated stainless steel (2.3 times), and also found that the nanocomposite coating improves the corrosion resistance significantly (89.25%). keywords: stainless steel, nanocomposite coating, electroco-deposition ecd, microhardness, corrosion resistance, and potentialastic polarization. 1. introduction stainless steel is environment friendly and abundantly available material that have good corrosion resistance, retains strength even at high temperatures, and easily machined, welded, formed and fabricated [1]. in order to enhance the mechanical properties bulk modification/alloying have been tried but limitations in alloying and adversely effects in its another properties has been reported. another recent way to improve its mechanical properties is with surface modification by developing composite coating on its surface. the surface coating technique available in this work that electroco-deposition (ecd) it has several advantages in developing metal matrix composite coatings among other coating processes such as, uniform depositions on complexly shaped substrates, low cost, good reproducibility and the reduction of waste [2]. ecd process has been in use successfully to develop such nanocomposite coatings from the past decades. the second phase can be hard oxide (al2o3,tio2, sio2) or carbides particles (sic, wc), etc., embedded in metals like cu, ni, cr, co and various alloys [3]. mailto:mahdih27@yahoo.com file:///c:/users/taiba/desktop/chapters/finish/kareemsallomi@yahoo.com mailto:hibahusamismail@yahoo.com hamid s. mahdi al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 110 (2014) 2 according to guglielmi’s model, composite electroplating takes place in two steps. during electrodeposition, solid particles are surrounded with cloud of adsorbed ions and these particles are weakly adsorbed at cathode surface by vander walls forces when they approach the cathode in the first step. and in the second step, loosely adsorbed particles get adsorbed strongly on cathode surface by coulomb force and consequently entrapped within metal matrix. the main drawback of this model is absence of mass transfer effect during ecd process. [4]. one of the common mechanism of codeposition process consist of five consecutive steps [5] shown in figure 1, five consecutive steps of co-deposition mechanism are: 1. formation of ionic clouds on the particles. 2. convection towards the cathode. 3. diffusion through hydrodynamic boundary layer. 4. diffusion through concentration boundary layer. adsorption at the cathode where particles are entrapped within metal deposit. fig. 1. mechanism of co-deposition process. hashimoto and abe [6], characterized zn-sio2 composites before and after corrosion test. znsio2 composites exhibited better corrosion resistance due to formation of protective corrosion products supported by sio2. akarapu [7], employed ecd process to develop a composite coating with cu matrix and ceramic oxide particles tio2 (particle size ~202 nm), al2o3 (particle size ~287 nm) as reinforcements. the coatings were developed with 10 g/l, 30 g/l and 0 g/l (unreinforced) concentrations in bath, at four different current densities (5, 8, 11, 14 a/dm2) with using copper sulfate bath in order to study the effect of current density and particle concentration in bath, on structure and properties of the coatings developed. the crystallite size was averagely 50-65 nm and a strong (220) texture was obtained in composite coatings and uncoated cu coatings determined from the xrd data. the composition and surface morphology of coatings were studied by using eds and sem. hardness and wear resistance of the coatings were determined by using microhardness tester and ball on plate wear tester, improved hardness and wear resistance of composite coatings were observed compared to the unreinforced copper coatings. borkar [8], in this work, nickel composite coatings (ni-al2o3, ni-sic, and ni-zro2) were successfully synthesized by dc, pc, and prc techniques to study effect of ecd methods on microstructure, mechanical, and tribological behavior. ni-cnt composite coatings were also fabricated by pulse ecd method to investigate cnt reinforcement effect on mechanical and tribological property. ni-al2o3 composites coatings were deposited to analyze effect of nanoparticles on properties of composite coatings. bahrololoom and sani [9] ,at first, particles reinforcement increases sharply at the beginning with increase in current density till it reaches maximum value followed by sharp decrease. therefore, hardness of composite coatings mainly increases due to the combined effect of both grain refining as well as of dispersive strengthening. saha and khan [10] ,when electroplating at lower current densities, nickel ions dissolved from anode (i.e. nickel) are transported at low rate and hence there is insufficient time for these ions to absorb on particles resulting in weak coulomb force between anions adsorbed on particles leading to lower concentration of electrodeposited particles in the composite coatings. on the other hand, at higher current densities, nickel ions dissolved from anode are transported faster than particles by the mechanical agitation which causes a decrease in codeposition of particles as well as hardness of composite coatings. therefore, selection of optimum current density is important to enhance the concentration of particles in the composite coatings. 2. experimental procedure the schematic diagram of electrocodeposition shown in figure 2. the nickel composite coatings hamid s. mahdi al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 110 (2014) 3 prepared by electrodeposition from watts solution suspended with nanoparticles. the nanoparticles used as reinforcement have (al2o3=135nm, zro2 = 40 nm, sic=80 nm) particle sizes. before electrodeposition electrolyte was stirred for about 24 hours using magnetic stirrer (model vs130sh). all the electrodeposition experiments were carried out at room temperature. a stainless steel plate (with an area of 4 cm2) and (99.99%) pure nickel plate (with an area of 10 cm2) were used as cathode and anode respectively, the steps of preparation stainless steel plate may be summarized as follow: 1. cutting the selected stainless steel (substrate) to the desired dimensions (20mm×20mm×0.5mm). 2. cleaning the stainless steel (substrate) by using acetone. this step was necessary to be sure to remove any surface oxide and organic impurities. 3. masking the substrates were leaving free only the surface to be coated. 4. dipping the masked substrate in distilled water in order to remove the small amount of oxides which might be formed during the exposure to the atmosphere while masking. since the substrates were prepared for deposition. after the deposition the tape used as a mask was removed and the samples were rinsed in distilled water and dried. these procedure were necessary to ensure the removal of any residuals of the watts bath, especially any loose adsorbed nanoparticles from the surface. standard watts solution consists of niso4 . 6h2o (nickel sulphate hexahydrate), nicl2. 6h2o (nickel chloride hexahydrate), and h3 . bo3 (boric acid). table 1 shows content of these chemicals for making of 1 l of electroplating bath. deposition parameters of ni-al2o3/ni-zro2/ni-sic and uncoated nickel coatings are reported in table 2. fig. 2. the schematic diagram of electrocodeposition. table 1, overview of the composition of chemicals for watts bath. bath composition niso4 . 6h2o 265g/l nicl2. 6h2o 48g/l h3. bo3 31g/l table 2, determination of deposition parameters. current density 0.5, 1, 2, 3 (a/dm2) dispersion al2o3/zro2/sic: 10, 20 (g/l) the surface morphology of the coatings and distribution of the particles was examined by scanning electron microscopic (sem) (tescan vega 3). assessments of microhardness of the coated and the uncoated stainless steel were determined by using digital vickers microhardness ester (th-715) with 9.807n load for 10 seconds. the hardness values were taken at 3 different points on the surfaces and average of these values were considered in the results. open circuit potential (ocp) and potentialastic polarization were used as the techniques for evaluating corrosion parameters of uncoated stainless steel and the composite coatings, the localized corrosion of the specimens were studied in 3.5% nacl solution. 3. results and discussion 1. scanning electron microscope (sem) studies figures (3-8) shows sem surface micrographs of the electrodeposited (al2o3, zro2 , and sic) composite coatings prepared at 10 g/l al2o3 in the bath and current densities 0.5, 1, 2, and 3 a/dm2. hamid s. mahdi al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 110 (2014) 4 fig. 3. surface morphology of electrodeposited ni-𝐀𝐥𝟐𝐎𝟑 coatings at 10 g/l (a) 0.5 a/dm 2 (b) 1 a/dm 2 (c) 2 a/dm 2 (d) 3 a/dm 2 . fig. 4. surface morphology of electrodeposited ni-𝑨𝒍𝟐𝑶𝟑 coatings at 20 g/l (a) 0.5 a/dm 2 (b) 1 a/dm 2 (c) 2 a/dm 2 (d) 3 a/dm 2 . fig. 5. surface morphology of electrodeposited ni-zro2 coatings at 10 g/l (a) 0.5 a/dm 2 (b) 1 a/dm 2 (c) 2 a/dm 2 (d) 3 a/dm 2 . hamid s. mahdi al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 110 (2014) 5 fig.6. surface morphology of electrodeposited ni-zro2 coatings at 20 g/l (a) 0.5 a/dm 2 (b) 1 a/dm 2 (c) 2 a/dm 2 (d) 3 a/dm 2 . fig. 7. surface morphology of electrodeposited ni-sic coatings at 10 g/l (a) 0.5 a/dm 2 (b) 1 a/dm 2 (c) 2 a/dm 2 (d) 3 a/dm 2 . fig. 8. surface morphology of electrodeposited ni-sic coatings at 20 g/l (a) 0.5 a/dm 2 (b) 1 a/dm 2 (c) 2 a/dm 2 (d) 3 a/dm 2 . hamid s. mahdi al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 110 (2014) 6 2. microhardness study the microhardness of the composite coatings were measured by using digital microhardness tester by applying 9.807n load for 10 seconds in order to ensure that the microhardness values are not affected by the substrate. the effect of current density on microhardness of ni-al2o3, nizro2 and ni-sic composite coatings developed at current densities 0.5, 1, 2, 3 a/dm2 shown in figures (9-12). the hardness values obtained for the composite coatings (ni-al2o3, ni-zro2 and ni-sic) are higher than the hardness values of substrate (pure stainless) 187.6 hv. in all the cases (ni-al2o3, ni-zro2 and ni-sic) coatings the microhardness values obtained followed the same trend. when the current density increased from 0.5 to 2 a/dm2, the hardness values increased and at 3 a/dm2 a little decrease in hardness values were obtained. in the present study at 2 a/dm2 current density higher hardness values shown in figure 12. fig. 9. effect of current density on microhardness of ni-𝐀𝐥𝟐𝐎𝟑 coating at current densities 0.5,1,2, and 3 a/dm 2 . fig. 10. effect of current density on microhardness of ni-𝐙𝐫𝐎𝟐 coating at current densities 0.5,1,2, and 3 a/dm 2 . fig. 11. effect of current density on microhardness of ni-𝐒𝐢𝐂 coating at current densities 0.5,1,2, and 3 a/dm 2 . fig. 12. microhardness of uncoated stainless steel and nickel composite coatings depostied at 10 and 20 (g/l) at 2 a/dm 2 . 3. corrosion study the corrosion bahavior of the composite coatings at defferent conditions were studied in sodium chloride at room tempature using open – circuit potential and potentiostatic polarization measurements.  open circuit potential (ocp)time measurements. the values of the open circuit potential (ocp) measured with respect to sce for 15 min in 3.5% nacl at room temperature showed the corrosion behavior of the uncoated and coated sample under equilibrated conditions in the solution. figure 13 illustrates the ocp – time curve of uncoated stainless steel. the potential is generally changed from initial negative value of -380mv vs (sce) to the positive direction of -223mv vs. (sce) and the potential almost remains stable at this value for 300 320 340 360 380 400 420 440 0.5 1 2 3m ic ro h ar d n es s (h v ) current density (a/dm2) 10 g/l 20 g/l 240 250 260 270 280 290 300 310 320 330 0.5 1 2 3 m ic ro h ar d n es s (h v ) current density (a/dm2) 10 g/l 20 g/l 190 200 210 220 230 0.5 1 2 3 m ic ro h ar d n es s (h v ) current dendity (a/dm2) 10 g/l 20 g/l 0 100 200 300 400 500 10 g/l 20 g/l m ic ro h ar d n e ss ( h v ) concentration al2o3 ni-zro2 ni-sic pure st. hamid s. mahdi al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 110 (2014) 7 more than 15 minutes. the increase in potential in the positive direction in this case may be due to the formation of the stable passive film.  potentiostatic polarization measurements polarization curve is commonly used as a plot of the electrode potential versus the logarithm of current density. the potentiostatic polarization for uncoated stainless steel and composite coatings specimens are presented in figures (14-17) which show cathodic and anodic polarization curves of uncoated stainless steel and composite coatings specimens in 3.5% nacl solution. fig. 13. the ocp – time curve of uncoated stainless steel. figure 14 indicates such curve, for uncoated stainless steel; which shows that corrosion potential (ecor) and corrosion current density (icor) values are (-214.7 mv) and (6.12 µa/cm 2 ) respectively. fig. 14. the potentiostatic polarization for uncoated stainless steel. figure (15 a) illustrates the case of nisic coatings at 20 g/l at 0.5, 1, 2 , and 3 a/dm 2 , which show that corrosion potential (ecor) and corrosion current density (icor) values are (-168.3 mv, -162.1 mv, -159.8 mv, and -154.6 mv) and (4.74 µa/cm 2 , 4.53 µa/cm 2 , 4.40 µa/cm 2 , and 4.39 µa/cm 2 ) respectively. the results show the obvious protection to the metal due to the ni-sic layer that covers the metal surface. figure (15 b) illustrates the case of ni-sic coatings at 10 g/l at 0.5, 1, 2 , and 3 a/dm 2 , which show that corrosion potential (ecor) and corrosion current density (icor) values are (-195.4 mv, -189.2 mv, -183.5 mv, and -177.9 mv) and (5.92 µa/cm 2 , 5.84 µa/cm 2 , 5.66 µa/cm 2 , and 4.87 µa/cm 2 ) respectively. the results show the obvious protection to the metal due to the ni-sic layer that covers the metal surface. the results show surface protection to the metal but, the protection is less than the protection provided by ni-sic coatings at 20 g/l. the magnitude of ecor is not a parameter that allows characterization of the corrosion phenomenon in a given system; its magnitude is determined by several factors, such as the nature of the metal, the environment or the electronic reactions that take place. fig. 15. potentiostatic polarization behaviour of nisic coatings at 0.5, 1, 2 , and 3 a/dm 2 a)10 g/l, and b) 20 g/l. hamid s. mahdi al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 110 (2014) 8 fig. 16. potentiostatic polarization behaviour of ni𝐙𝐫𝐎𝟐 coatings at 0.5, 1, 2 , and 3 a/dm 2 a)10 g/l, and b) 20 g/l. fig. 17. potentiostatic polarization behavior of ni𝐀𝐥𝟐𝐎𝟑 coatings at 0.5, 1, 2 , and 3 a/dm2 a)10 g/l, and b) 20 g/l. in all the cases (ni-al2o3, ni-zro2 and nisic) coatings the polarization curves obtained have the same behavior at increased concentration of (al2o3, zro2 and sic) in the nanocoating. the corrosion current decreases and the corrosion potential shifts to a more positive potential resulting in a decreased corrosion rate. this results show the concentration 10 g/l at (al2o3, zro2 and sic) has the largest corrosion current because of the void space on the surface leading to entering solutions to the metal, causing dissolutions faster than the surface with concentration 20 g/l. from the above results the examination of uncoated and coated stainless steel in 3.5% nacl solution indicates that excellent corrosion resistance is observed for ni-al2o3 coatings at 20 g/l and 3 a/dm2. the best value of corrosion rate for uncoated and coated stainless steel are shown in table 3 and figure 18. the efficiency in improvement of current density and corrosion rate (mpy) are due to composite coatings. they can be obtained by using the following relations (1) and (2) : efficiency in current density (icor ) = icor uncoated − icor coated icor uncoated × 100% ... (1) efficiency in corrosion rate (c. r) = c.r uncoated − c.r coated c.r uncoated × 100% ...(2) table 3, the best corrosion parameters of specimens in 3.5% nacl. type ex. no ecor (mv) icor (µa/cm2) icor % mpy c.r % ni𝐀𝐥𝟐𝐎𝟑 4 -83.2 1.95 68.13 1.81* 10-1 80.15 8 -41.2 0.49429 91.92 0.98* 10-1 89.25 ni𝐙𝐫𝐎𝟐 12 -137.4 3.73 39.05 3.43* 10-1 62.39 16 -110.0 2.88 52.94 2.7* 10-1 70.39 ni-sic 20 -177.9 4.87 20.42 5.23* 10-1 43.65 24 -154.6 4.39 28.26 4.56* 10-1 50 hamid s. mahdi al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 110 (2014) 9 fig. 18. the best corrosion parameters of specimens in 3.5% nacl. 4. conclusions in the present study, ni-al2o3, ni-zro2, and ni-sic nanocomposite coatings were developed successfully by using electroco-deposition process on the stainless steel (aisi 304) from watts bath with different current densities and powders concentrations. from the detailed investigation of the results obtained, the following conclusions can be drawn: 1. the microhardness values obtained for nial2o3, ni-zro2, and ni-sic composite coatings are higher than the uncoated stainless steel hardness (hv). 2. the maximum of microhardness at (2 a/dm 2 ):  for al2o3, maximum for 10 g/l was 1.87 and 2.30 times increase for 20 g/l.  for zro2 , maximum for 10 g/l was 1.54 and 1.74 times increase for 20 g/l.  for sic, maximum for 10 g/l was 1.11 and 1.19 times increase for 20 g/l. 3. the microhardness of the ni-al2o3, ni-zro2, and ni-sic composite coatings increased with increasing the content of nanoparticle loading in the electrolyte bath due to enhanced dispersion strengthening effects. 4. the corrosion resistance of the composite coatings was higher than the uncoated stainless steel. 5. the optimum corrosion rate achieved at (20 g/l and 3 a/dm 2 ):  for al2o3 was 89.25%.  for zro2 was 70.39%.  for sic was 50%. 5. references [1] brandes e. a. and g. b. brook, “smithells metals reference book”, (7th edition), edited by, butterworth-heinemann, oxford, 2000. mechanical metallurgy, by: g e dieter, mcgraw hill, singapore. [2] stojak. j.l, fransaer. j, talbot. j. b, “review of electrocodeposition”. edited by, r.c. alkire, d.m. kolb, adv. electrochem. sci. eng. wiley-vch verlag, weinheim, 2002. [3] gul. h, kilic. f ̧aslan. s, alp. a, akbulut. h, “characteristics of electro-co-deposited ni–al2o3 nano-particle reinforced metal matrix composite (mmc) coatings”. wear, vol. 267, pp. 976–990, 2009. [4] kuo s.l., chen y.c., ger m.d., “nanoparticles dispersion effect on ni/al2o3 composite coatings”. materials chemistry and physics, vol. 86, pp. 5-10, 2004. [5] low c. t. j., r. g. a. wills and f. c. walsh, “electrodeposition of composite coatings containing nanoparticles in a metal deposit”. surf. coat. technol., vol. 201, pp. 371-383, 2006. [6] hashimoto s. and abe m., “the characterization of electrodeposited zn-sio2 composites before and after corrosion test”. corrosion science, vol. 36, pp. 21252137,1994. [7] ashok akarapu, “surface property modification of copper by nanocomposite coating”, m.s.c. thesis in metallurgical and materials engineering, department of metallurgical & materials engineering, national institute of technology, rourkela, 2011. [8] tushar borkar, “electrodeposition of nickel composite coatings”. submitted to the faculty of the graduate college of the oklahoma state university in partial fulfillment of the requirements for the degree of master of science, 2010. [9] bahrololoom m. e. and sani r., “the influence of pulse plating parameters on the hardness and wear resistance of nickelalumina composite coatings”. surface and coatings technology, vol. 192, issue 2-3, pp. 154-163, 2005. [10] saha. r.k, khan. t.i, “effect of applied current on the electrodeposited ni–al2o3 composite coatings, surface & coatings technology”. vol. 305, no. 3, 2010, pp890895, 2010. (2014)110 ، صفحت4، العذد10دجلت الخىارزهي الهنذسيت الوجلم ههذي صالححاهذ 10 الطالء بوركب نانىي تحسين الصالدة وهقاوهت التآكل للفىالر الوقاوم للصذأ بىاسطت ***هبه حسام اسواعيل **كرين نعوت سلىهي *حاهذ ههذي صالح جبٍعخ ثغذاد /يميٍخ اىوْذعخ اىخياسصً /قغٌ هْذعخ اىزظٍْع اىَؤرَذ***،**،* mahdih27@yahoo.com : اىجشٌذ االىنزشىًّ* kareemsallomi@yahoo.com **ًّاىجشٌذ االىنزشى: hibahusamismail@yahoo.com : اىجشٌذ االىنزشىًّ*** الخالصت ٍْخفغ اىثَِ ، ادٌخٍقبىً جٍذ ىيزآمو فً دسجبد اىحشاسح األعزًى ىاىنوشثبئٍخ حىيحشاساىَيطيخ ٍِ اىَياد ( 304aisi)اىفيالر اىَقبىً ىيظذأ ٌُعذ ىغشع رحغٍِ خياص اىغطح ٍثو اىظالدح ىٍقبىٍخ اىزآمو ٍع .ىٍقبىٍخ اىشذ ٍِ ّبحٍخ اىخياص اىٍَنبٍّنٍخ ٍثو اىظالدح اًا جٍذ دعىنْن يُ ، فش ثنثشحاىٍزي ع اىطالء اىَشمت ٍع ٍظفيفخ اىٍْنو ىيع( electroco-deposition)فً هزا اىجحث اعزخذٍْب عَيٍخ .اىطالء ثبىَشمجبد اىْبّيي ثبعزخذاًرعذٌو اىغطح رٌ رْفٍز اىطالء فً رشمٍضاد ٍخزيفخ . al2o3 (135nm), zro2 (40nm), and sic (80nm) :-ىًعيى اىْحي اىزب ىجضٌئبد اىمغٍذ اىغٍشاٍٍل مَعضصاد (10g/l 20 ىg/l) ، 2 ,1 ,0.5)ىمزىل مثبفخ اىزٍبس ٍخزيفخ, and 3 a/dm 2 ىرشمٍض ُ اجو دساعخ رؤثٍش مثبفخ اىزٍبسً( watts)ثبعزخذاً حَبً ( ىدساعخ ، اىوذف االعبط ٍِ هزا اىجحث هي رحغٍِ اىظالدح ىٍقبىٍخ اىزآمو ىيفيالر اىَقبىً ىيظذأ .ىخظبئظن اىجضٌئبد فً اىحَبً عيى ثٍْخ اىطالء اىَْجض ىمزىل رحيٍو رؤثٍش اىجضٌئبد اىْبّيٌخ عيى ، رخذً فً اىجحثعيى اىغييك اىَجوشي ىاىٍَنبٍّنً ىيفيالر اىَظ( electroco-deposition)رؤثٍش طشٌقخ ىقذ اجشي فحض اىظالدح ثياعطخ (. sem)دساعخ رشنٍو عطح اىطالء ثبىَشمت اىْبّيي ٍِ خاله اىَجوش االىنزشىًّ مزىل رٌ ى .خظبئض اىطالء اىَشمت ثبعزخذاً طبقخ %3.5ثزشمٍض (nacl) ٍحييه مييسٌذ اىظيدٌيً مو فًمزىل رٌ اخزجبس اىزآ، (microhardness-hv)االخزجبس اىشقًَ ىيظالدح اىذقٍقخ ( ٍشح2.3 )ىمزىل طالدح عبىٍخ ثْغجخ ، أظوشد اىْزبئج اُ اىطالء ثبىَشمجبد اىْبّيٌخ ىن عطح أٍيظ ٍذٍج .ىطبقخ االعزقطبة (ocp)اىذائشح اىَفزيحخ .ٍقبسّخ ثبىفيالر غٍش اىَطيً %89.25ىٍخ اىزآمو قذ رحغْذ ثشنو مجٍش ثْغجخ ىاٌضآ ىجذ اُ ٍقب، ٍقبسّخ ثبىفيالر اىَقبىً ىيظذأ غٍش اىَطيً mailto:mahdih27@yahoo.com file:///c:/users/taiba/desktop/chapters/finish/kareemsallomi@yahoo.com mailto:hibahusamismail@yahoo.com (microsoft word 108119 \310\323\343\311 \346\343\325\330\335\354) al-khwarizmi engineering journal al-khwarizmi engineering journal,vol. 13, no. 3, p.p. 108119 (2017) enhancing the compressive strength and density of cement mortar by the addition of different alignments of glass fibers and styrene butadiene rubber mustafa m. hamza* besma m. fahad** * department of materials engineering /mustansiriya university ** department of materials engineering /mustansiriya university *email: eng.mustafa.al.taey@gmail.com **email: besma_alazzawi@yahoo.com (received 19 june 2016; accepted 21 february 2017) https://doi.org/10.22153/kej.2017.02.005 abstract in the field of construction materials the glass reinforced mortar and styrene butadiene mortar are modern composite materials. this study experimentally investigated the effect of addition of randomly dispersed glass fibers and layered glass fibers on density and compressive strength of mortar with and without the presence of styrene butadiene rubber (sbr). mixtures of 1:2 cement/sand ratio and 0.5 water/cement ratio were prepared for making mortar. the glass fibers were added by two manners, layers and random with weight percentages of (0.54, 0.76, 1.1 and 1.42). the specimens were divided into two series: glass-fiber reinforced mortar without sbr and glass-fiber reinforced mortar with 7% sbr of mixture water. all specimens were tested after curing for 7 and 28 days, glass-fiber reinforced mortar exhibited better properties than control mortar in improvement of compressive strength and lowering the density after curing for 28 days due to the completion of cement hydration reaction.. for compressive strength the best results were achieved with 1.42 wt.% layers glass-fiber reinforced mortar with 7% sbr which gave 41.56 mpa. on the other hand, the addition of 1.42 wt.% random glass-fiber without sbr addition caused the beast reduction in density by 10.6% and produced lighter structure than control sample. keywords: random glass fibers, glass fibers layers, sbr, compressive strength, density. 1. introduction cement mortar that is free from any fibers addition develops cracks due to the plastic and dry shrinkage as well as changing in volume, consequently these cracks lead to elastic deformation of cement mortar.[1,2] the addition of polymers to cement mortar provides a noticeable improvement in workability, extensibility, adhesion, and water tightness over conventional cement mortar.[3] the addition of glass fibers to cement mortar is one of adopted methods to improve the properties, performance and durability of mortar. this addition constructs a cohesive structure which overcomes the property of dimensional instability due to the influence of external conditions because of the fragility of the mortar. [5] glass fibers reinforced mortar is considered a new building material which has superior properties than ordinary mortar. among these properties are improved compressive strength and lower density which produce a light weight structure. [4] the possibility of using a glass fiber reinforced concrete system was recognized by russians in the 1940s these were unsuccessful due to the alkaline nature of the cement attacking and breaking down the fibers. the problem was solved in the mid-1960s with the development of alkaline resistant glass fibers containing a high mustafa m. hamza al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 108119 (2017) 109 level of zirconium dioxide. academic studies have continued to develop this addition and recently has become widely used for many construction applications such as facades, balconies, fountains, ceilings, rail applications and architectural units.[6] the first emulsion polymerized sbr was known in the 1930’s as buna s. it was prepared by i. g. farbenindustrie in germany. in 1940 the u.s. government established the rubber reserve company to start a stockpile of natural rubber and a synthetic rubber program. these programs were expanded when the united states entered world war ii. the synthetic rubber efforts were initially focused on a hot polymerized (41°c) emulsion polymerized styrene butadiene rubber. utilization of sbr was limited to the production of car and light truck tires and truck tire retread compounds, it was entered in the field of building materials recently. [7] bridges failure as a result of earthquakes, such as 1989 loma prieta earthquake in california, usa, attracted the attention of the engineering community to innovate a new solutions to avoid these situations. h. saadatmanesh, m. r. ehsani, and m. w. li, in 1994,[7] presented a new technique for seismic strengthening of concrete columns, this technique used wrapping thin, flexible high strength fibers straps around the column to improve the ductility and strength. the stress-strain models for concrete surrounded with composite straps indicated significant increasing in compressive strength and strain at failure when compared with the stress-strain behavior of nonsurrounded concrete.[8] mahdi s. essa and nada f.hassan, in 2008,[9] conducted a study involving the effect of adding styrene butadiene rubber emulsion on compressive strength of cement mortar with various percentages (10%, 25%, 35% ) by volume of water after curing for (7, 28, 60) days. they also studied the effect of this addition on compressive strength, absorption, slump loss with time and flexural strength of concrete of mix 1:2:4 with 0.45 water to cement ratio by weight. the results showed that the addition of styrene butadiene rubber negatively affects the compressive strength at all ages. initial and final setting time decrease with increasing the percentage of styrene butadiene rubber. addition of styrene butadiene rubber to concrete decreased the compressive strength at early ages (7 days) and increased it at later ages. it also reduced the absorption of concrete and slump loss with time and increased the flexural strength.[9] manjunath v melkundi and vaijanath halhalli, in 2013,[10] investigated the behavior of conventional concrete, styrene butadiene rubber latex-modified convectional concrete, steel fiber reinforced concrete and styrene butadiene rubber latex modified steel fiber reinforced concrete in compressive strength, split tensile strength and flexural strength. the results showed that the concrete added with fiber and latex behaved much better with regards to higher first crack load and ultimate load and also lesser deflection.[10] rasha salah mahdi, in 2014,[4] studied the effect of glass fibers on compressive strength and flexural strength of cement mortar using three mixes of glass fibers reinforced mortar with glass fibers content of (1, 1.5 and 2)% by weight of cement. the results showed that the mortar mixed with 1% fiber content gave a higher compressive and flexural strength than the mortar mixed with 2% fiber content. [4] 2. aims this work aims to study the effect of glass fibers addition in layers and random manner with and without addition of sbr on density and compressive strength of cement mortar compared with control specimens, as well as studying the effect of curing for 7 and 28 days on these specimens. 3. experimental procedure 3.1. materials 3.1.1. cement sulfate-resistant portland cement (type v) was used, it was of (tasluja) al-jissir trade mark from lafarge cement factory. in order to avoid the humidity effect on cement properties it was stored in a dry place. several chemical and physical tests were carried out in ncclr (national center for construction labs. & researches) to verify its specification, the cement was identical to the iraqi standard specification no.5/1984. table (1) and table (2) show the chemical composition and physical properties of the cement, respectively, according to the iraqi standard specification no.5/1984. mustafa m. hamza al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 108119 (2017) 110 table 1, chemical composition and properties of cement. chemical composition & properties tests results% limits sio2 19.74 ـــــــــــــــ al2o3 4.28 ـــــــــــــــ fe2o3 5.04 ـــــــــــــــ cao 64.13 ـــــــــــــــ mgo 2.92 ≤ 5% so3 2.36 ≤ 2.5% c3a 2.82 ≤ 3.5% lime saturation factor (l.s.f) 0.98 ≤ (1.022-0.66)% insoluble residue (i.r) 0.96 ≤ 1.5% loss on ignition(l.o.i) 3.92 ≤ 4% table 2, physical properties of the cement. 3.1.2. sand sand from al-ukhaidhir region was used as fine aggregate with specific gravity of (2.58) and fineness modulus of (2.17). a sieve analysis was carried out in the national center for construction labs. & researches (ncclr) of the iraqi ministry of construction and housing, in order to know the grading of the fine aggregate according to the iraqi standard specification no.45/1984. table (3) shows the results of sieve analysis process and the fig (1) shows the upper and lower limits of iraqi specification and the used sand. table 3, the results of sieve analysis process. fig. 1. the upper and lower limits of iraqi specification and the used sand. 2.1.3. glass fibers a chopped strand mats glass fibers of china beihai trade mark was used. table (4) shows some properties of glass fibers. layers of glass fibers were of thickness (2mm) and fiber length (3cm). it was cut into two shapes layers and random fibers as shown in plate (1). table 4, some of glass fibers properties property value modulus of elasticity (e) 72 gpa density 2.58 g/cm3 tensile strength 1.9 gpa compression strength 150 mpa poisson's coefficient 0.22 sieve size weight in gram retained % passed % limits of third area % 10 mm 0 0 100 100 4.75 mm 1 0.133 99.9 90-100 2.36 mm 57 7.6 92.4 85-100 1.18 mm 132.5 17.66 82.3 75-100 600 � 277.5 37 63 60-79 300 � 506.5 67.53 32.5 12-40 150 � 655.5 87.4 12.6 0-10 salts% 714 95.2 4.8 5 physical properties results limits fineness (m/kg) (blain’s method) 358 ≥ 250 setting time (hr : min) (vicat’s method) -initial setting -final setting 2 : 15 4 : 15 ≥ 45 min. ـــــــــــــــــــ soundness (autoclave) -0.1 ≤ 0.8 compressive strength (mpa) -3 days -7days 19.5 25.5 15 23 mustafa m. hamza al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 108119 (2017) 111 plate. 1. a: random glass fibers, b: glass fibers layers. 3.1.4. styrene butadiene rubber (sbr) the polymer which is used in this study was a liquid resin of styrene butadiene rubber (sbr). sbr is an aqueous dispersion of (25%) styrene and (75%) butadiene copolymer when mixed with cementitious products giving high performance water resistance properties, it is especially suitable for primers, renders, mortars and floors with high abrasion resistance and for patching and bonding onto substrates of low suction. the sbr used in this research was of sbi trade mark in uae. table (5) shows the typical properties of the used sbr and all of the information from the manufacturer data sheet. table 5, typical properties of used sbr appearance fluid liquid color milky white change to transparent when dry density 1050 kg/in3 solid content 36 38 % ph 8-9 temperature resistance -20 up to +90 c 3.1.5. water tap water was used for mixing process and distilled water for curing process at (ncclr) national center for construction labs. & researches. 3.2. experimental work mixtures of 1:2 cement/sand ratio and 0.5 water/cement ratio were prepared for making mortar. the glass fibers were added by two manners, layers and random with weight percentages of (0.54, 0.76, 1.1 and 1.42). the specimens were divided into two series: glassfiber reinforced mortar free from sbr and glassfiber reinforced mortar with 7% sbr of mixture water. table (6) shows the mix design proportions. table 6, mix design proportions. specimens cement kg/m3 sand (kg/m3) w/c ratio water (l/m3) sbr (l/m3) glass fibers wt.% control mortar 627.9 1255.7 0.5 313.93 0 0 glass fibers reinforced mortar without sbr 627.9 1255.7 0.5 313.93 0 0.54 627.9 1255.7 0.5 313.93 0 0.76 627.9 1255.7 0.5 313.93 0 1.1 627.9 1255.7 0.5 313.93 0 1.42 glass fibers reinforced mortar with 7% sbr 627.9 1255.7 0.5 291.96 21.96 0.54 627.9 1255.7 0.5 291.96 21.96 0.76 627.9 1255.7 0.5 291.96 21.96 1.1 627.9 1255.7 0.5 291.96 21.96 1.42 the glass fibers were weighed before mixing as shown in plate (2:a). for achieving a homogenous mixing of the materials, sand, cement, and glass fibers were mixed together by hand for about two minutes in dry state, the water was added to the mixture and mixed for four minutes according to astm c305.[11] plate(2:b) shows the preparation of random glass-fiber reinforced mortar. after the mixing process the resulting mortar was poured in cast iron molds of (15×15×15) cm. dimensions. in glass-fiber layers reinforcing a glass-fiber mat was cut into square layers of (15×15) cm. dimensions. the mortar and glass fiber layers were sequentially fed into molds in order to produce a cohesive structure. plate (3:a) shows the molding of glass fibers layers reinforced mortar. the layers were well compacted by hand until the mixture water penetrate through it which made better bonding between the cementitious matrix and glass-fiber layers reinforcement as shown in plate(3:b). after the solidification of specimens they were de mustafa m. hamza al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 108119 (2017) 112 molded and cured at temperature of (20∓5)°c for 7 and 28 days at controllable room of (50∓5)% humidity as it is shown in plate (4). plate. 2. a: glass fibers weighing, b: preparation of gf mortar. plate. 3.a: molding of glass fibers layers reinforced mortar, b: glass fibers layer compacting. plate. 4. curing at a: controlled temperature, and b: controlled humidity. 4. tests 4.1. density according to astm c642-97[12], after the curing process the regular shape specimens were dried in oven at temperature of (100-110)°c for 24 hours then removed and its weight was recorded. after that the specimens were immersed in water of temperature (20 ∓5 °c) for 7 and 28 days, then removed and its weight was recorded. the density was computed according to equation (1) density �kg/m�� = �kg�����ℎ� ��� �kg���� !" ��� − �kg�����ℎ� ��� × $kg/m3&'�()��� �*��� … (1) 4.2. compression test according to bs 1881-108:1983,[13] the compressive strength of (15× 15× 15)cm. dimensions cubic specimens of glass fibers reinforced mortar with styrene butadiene rubber compared with control specimens were tested by the universal compressive machine of (controls) trade mark which was manufactured in milan, italy, it is shown in plate.5. plate. 5. universal compressive machine. mustafa m. hamza al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 108119 (2017) 113 5. results and discussion 5.1. density 5.1.1. glass fibers reinforced mortar without sbr the specimens were tested after curing for (7 and 28) days and the results are shown at table (6). the specimens with the addition of glass fibers (random and layers) revealed decreasing in density as shown in fig.(2) & fig.(3), this decreasing resulted from the light weight glass fibers which made the specimens lighter than the control specimens resulting in decreasing of density due to the direct proportionality between the weight and density.[14] table 6, results of density testing for glass fibers reinforced mortar without sbr. mortar type glass fibers wt.% curing days density g/cm3 reduction % control mortar ـــــــــــ ــــــــــــ 2.3 7 ــــــــــــ 2.316 28 reinforced by layers glass fibers 0.54 7 2.162 5.86 28 2.193 3.9 0.76 7 2.160 6.3 28 2.190 5.22 1.1 7 2.132 7.3 28 2.144 6.1 1.42 7 2.110 8.56 28 2.161 6.6 reinforced by random glass fibers 0.54 7 2.141 6.9 28 2.310 5.3 0.76 7 2.114 8.0 28 2.248 5.6 1.1 7 2.100 8.7 28 2.278 7.4 1.42 7 2.054 10.6 28 2.140 6.7 fig. 2. effect of random glass fibers addition on the density of mortar without sbr. fig. 3. effect of glass fibers layers addition on the density of mortar without sbr 5.1.2. glass fibers reinforced mortar with sbr all results are shown in table (7), fig. (4) and fig. (5) show the decreasing in density of mortar after the addition of random and layers of glass fibers with 7% sbr, respectively. the increasing in density in this case is lower than glass fibers reinforced mortar without sbr because the sbr fill the pores in the specimen which increase the density. the random glass fibers addition showed higher reduction in density than layers. table 7, results of density testing for glass fibers reinforced mortar with sbr. mortar type glass fibers wt.% curing days density g/cm3 reduction % control mortar ـــــــــــ ــــــــــــ 2.3 7 ــــــــــــ 2.316 28 reinforced by layers glass fibers 0.54 7 2.226 3.22 28 2.256 1.42 0.76 7 2.162 5.13 28 2.195 1.64 1.1 7 2.143 6.83 28 2.163 2.42 1.42 7 2.125 7.6 28 2.175 4.4 reinforced by random glass fibers 0.54 7 2.216 3.65 28 2.311 1.51 0.76 7 2.161 5.35 28 2.252 2.12 1.1 7 2.135 6 28 2.280 2.5 1.42 7 2.078 8.35 28 2.156 5.53 mustafa m. hamza al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 108119 (2017) 114 fig. 4. effect of random glass fibers addition with sbr after curing for 7 and 28 days. fig. 5. effect of layers glass fibers addition with sbr after curing for 7 and 28 days. a comparison between random glass fibers mortar and layers glass fibers mortar with sbr and their effect on density of mortar specimens at 7 & 28 days of curing relative to control specimens is shown in fig. (6) and fig. (7), respectively. fig. 6. comparison between glass fibers reinforced mortar without sbr and glass fibers reinforced mortar with sbr after curing for 7 days. fig. 7. comparison between glass fibers reinforced mortar without sbr and glass fibers reinforced mortar with sbr after curing for 28 days. from the previous figures, the following can be noticed: • the addition of glass fibers in both random and layers manner decreased the density of mortar. the density was directly proportional to the weight according to the density rule which is the weight divided by the volume, the light weight glass fibers made the specimens lighter than control specimens and consequently reduced the density.[14] • random glass fibers addition showed higher reduction in density of mortar (10.6%) than layers glass fibers (8.56%) compared with control specimens. • random and layered glass-fiber addition with 7% sbr caused lower reduction in density than glass fibers addition without sbr. the reduction mustafa m. hamza al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 108119 (2017) 115 was (8.35%) and (7.6%) for random and layers, respectively. • 7 days curing gave higher reduction than 28 days due to the completion of cement hydration reaction which produce a dense structure. 5.2. compressive strength 5.2.1 glass fibers reinforced mortar without sbr the addition of glass fibers (random and layers) to mortar increased the compressive strength and all results are shown in table (8). the best addition was with (1.1) % by weight. the further addition caused reduction in compressive strength but still higher than control specimens as shown in fig. (8) and fig.(9). the glass fiber enhances the bond strength and this is the explanation of increasing in compressive strength by the addition glass fiber, but the further addition lowers the compressive strength due to the brittleness of glass.[15] table 8, results of compressive strength testing for glass fibers reinforced mortar without sbr mortar type glass fibers wt.% curin g days compressiv e strength mpa increasin g % control mortar ــــــــــ ـ ــــــــــــ 15.404 7 ــــــــــــ 20.28 28 reinforce d by layers glass fibers 0.54 7 18.055 17.20 28 25.271 24.61 0.76 7 18.842 22.32 28 27.578 35.99 1.1 7 19.32 25.42 28 33.48 65.10 1.42 7 18.376 19.29 28 24.341 20.00 reinforce d by random glass fibers 0.54 7 15.644 1.56 28 21.724 7.12 0.76 7 16.142 4.79 28 22.689 11.88 1.1 7 16.914 9.80 28 24.663 21.61 1.42 7 16.464 6.88 28 23.156 14.18 fig. 8. effect of random glass fibers addition on mortar after curing for 7 and 28 fig. 9. effect of glass fibers layers addition on mortar after curing for 7 and 28 days. 5.2.2. glass fibers reinforced mortar with sbr all results are shown in table (9), fig. (10) and fig.(11) show the improving in compressive strength after the addition of random and layered glass-fiber with 7% sbr, respectively. the addition of glass fibers with 7% sbr caused increasing in compressive strength until the glass fibers reached (1.1) % by weight. the more addition caused a reduction in compressive strength but still higher than control specimens. the layered glass fibers addition showed higher increasing in compressive strength than random addition. mustafa m. hamza al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 108119 (2017) 116 table 9, results of compressive strength testing for glass fibers reinforced mortar with sbr mortar type glass fibers wt.% curin g days compressiv e strength mpa increasin g % control mortar ــــــــــ ـ ــــــــــــ 15.404 7 ــــــــــــ 20.28 28 reinforce d by layers glass fibers 0.54 7 26.311 70.80 28 33.702 66.18 0.76 7 28.206 83.10 28 39.87 96.60 1.1 7 30.71 99.36 28 41.56 104.93 1.42 7 28.88 87.48 28 39.4 94.28 reinforce d by random glass fibers 0.54 7 24.906 61.68 28 32.643 60.96 0.76 7 27.43 78.07 28 35.75 76.30 1.1 7 28.66 86.10 28 40.71 100.74 1.42 7 26.15 69.76 28 37.22 83.53 fig. 10. effect of random glass fibers addition with sbr to mortar after curing for 7 and 28 days. fig. 11. effect of layers glass fibers addition with sbr to mortar after curing for 7 and 28 days. to clarify the effect of adding random and layers glass fibers with and without sbr on compressive strength, a comparison with control specimens is shown in fig. (12) and fig.(13) after 7 & 28 days of curing, respectively. fig. 12. comparison between the effect of random and layers glass fibers with and without sbr on compressive strength of mortar after 7 days of curing. fig. 13. comparison between the effect of random and layers glass fibers with and without sbr on compressive strength of mortar after 7 days of curing. from the previous figures, the following observation can be noticed: � the addition glass fibers (random and layers) to mortar improved the compressive strength compared with control specimens. the best compressive strength was achieved at (1.1) weight percentage of glass fibers and the further mustafa m. hamza al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 108119 (2017) 117 addition caused a reduction in compressive strength but still higher than control specimens. the increasing was (21%) and (65%) for random and layers, respectively. the glass fibers enhanced the bond strength and this is the explanation of increasing in compressive strength by the addition glass fibers but the increasing in the addition of glass fibers lowered the compressive strength due to the brittleness of glass fibers.[15] � addition of glass fibers (random and layers) with 7% sbr caused higher increasing in compressive strength and better addition was (1.1) wt.% with 7% sbr. the increasing was (100.4%) and (104.9%) for random and layers, respectively. the further addition negatively affected the compressive strength but still higher than control specimens. the layer addition produced higher results than random addition. � the curing age had noticeable effect in improving the compressive strength of mortar where 28 days of curing gives better results than 7 days of curing. 6. conclusions 1. the addition of glass fibers in both random and layers manner to cement mortar caused a reduction in density. the higher reduction was with glass fibers of (1.42 wt. %). the random addition gave more reduction in density than the layered one. 2. the addition of 7% sbr to glass fibers reinforced mortar caused less reduction in density than glass fibers addition without sbr. 3. the curing age for 7 days caused more reduction than 28 days due to the completion of cement hydration reaction which produced more dense structure. 4. both random and layered glass fibers addition to mortar improved the compressive strength. the layers addition has the better results over the random one and the best weight percentage was (1.1). 5. addition of 7% sbr to glass-fiber reinforced mortar caused higher improvement in compressive strength than that without sbr. 6. the curing for 28 days has better improvement in compressive strength than 7 days of curing. 7. references [1] deshmukh s.h. , bhusari j. p , zende a. m. , "effect of glass fibers on ordinary portland cement concrete" , iosr journal of engineering june. 2012, vol. 2 , issue 6 , pp. 1308-1312. [2] p srinivasa rao , t seshadri sekhar , "compressive, split tensile, flexural strength of self compacted concrete", i-manager's journal on future engineering and technology journal , volume 3 , issue 1 , pages 78, 2008. [3] v. ramakrishnan, “latex-modified concretes and mortars", transportation research board, national research council , washington ,1992. [4] rasha s. mahsi, "experimental study effect of using glass fiber on cement mortar", journal of babylon university/engineering sciences, vol.22, no.1, 2014. [5] m. h. ahmad, h. awang, "effect of steel and alkaline-resistance glass fibre on mechanical and durability properties of lightweight foamed concrete", advanced materials research, vol. 626, pp. 404-410, 2013. [6] abdullah, muna m. and eman k. jallo, " mechanical properties of glass fiber reinforced concrete", al-rafadain engineering journal, vol.20, issue 5, p128135, 2012. [7] v. c. chandrasekaran, "rubber as a construction material for corrosion protection: a comprehensive guide for process equipment designers", john wiley & sons, 2010. [8] h. saadatmanesh, m. r. ehsani, and m. w. li, "strength and ductility of concrete columns externally reinforced with fiber composite straps", aci structural journal, v. 91, no. 4 july-august 1994. [9] mahdi s. essa and nada f. hassan, "effect of adding styrene butadiene rubber admixture (sbr) on concrete properties and bond between old and new concrete", journal of kerbala university, vol. 6. no.2. scientific. 2008. [10] manjunath v melkundi and vaijanath halhalli, "experimental investigation of sbrlatex modified steel fiber reinforced concrete", international journal of engineering research & technology, vol. 2, no.11, 2013. [11] astm c305, "mechanical mixing of hydraulic cement pastes and mortars of plastic consistency", 2004. [12] astm c642-97, "standard test method for mustafa m. hamza al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 108119 (2017) 118 density, absorption, and voids in hardened concrete", 2006. [13] bs 1881-108, "testing concrete. method for making test cubes from fresh concrete", 1983. [14] david halliday, robert resnick and jearl walker "fundamentals of physics extended", 10th edition, wiley inc., 2014. [15] rana hashim ghedan, "effect of addition carbon and glass fibers on bond strength of steel reinforcement and normal concrete", eng. & tech. journal, vol.31, no.1, 2013. )2017( 108-119، صفحة 3د، العد13دالهندسية المجلجلة الخوارزمي م مصطفى محمد حمزة 119 يرين ستاال مستحلبمختلف من الياف الزجاج و توزيع دامباستخللمالط االنضغاطتحسين مقاومة بيوتادايين ** بسمة محمد فهد *مصطفى محمد حمزة هندسة المواد/ الجامعة المستنصرية قسم* هندسة المواد / الجامعة المستنصريةقسم ** gmail.comeng.mustafa.al.taey@ :اإللكتروني * البريد yahoo.combesma_alazzawi@ ** البريد اإللكتروني : الخالصة من المواد الحديثة في مجال المواد اإلنشائية. يهدف هذا البحث د) تعsbrستايرين بيوتادايين ( مستحلبالمالط المدعم بألياف الزجاج والمضاف لها ). sbrاومة انضغاط المالط مختبرياً في حالة وجود او عدم وجود مادة (لدراسة تأثير اضافة الياف الزجاج العشوائية وطبقات الياف الزجاج على كثافة و مق ). تم اضافة الياف الزجاج بطريقتين عشوائية ٠٫٥اإلسمنت ( ىلا ماءلا نسبة و ) لرم -نتاسم ( ١:٢وزنية لطخ تم تحضير خلطات من المالط بنسبة ) واألخرى مدعمة sbrسلسلتين احداهما مدعمة بألياف الزجاج بدون اضافة (). قسمت العينات الى ١٫٤٢, ١٫١, ٠٫٧٦, ٠٫٥٤وطبقات بنسب وزنية ( ً يوم ٢٨و ٧) من ماء الخلطة. تم فحص العينات بعد غمرها بالماء لمدة sbr( %٧بألف الزجاج مع اضافة . المالط المدعم بألياف الزجاج أظهر تحسينا ا ٢٨). اإلنضاج بعمر sbr( %٧لنتائج كانت مع العينات المدعمة بألياف الزجاج والمضاف لها في مقاومة االنضغاط مقارنة مع عينات القياس. اما افضل ا ً يوم اظهر افضل النتائج بسبب اكتمال تفاعل الماء مع اإلسمنت. ا عدنان وابتهال و رونق al-khwarizmi engineering journal, vol. 10, no. 1, p.p. improve wear resistance on particles rei ibtihal a. mhmood* rawnaq *department of machines and equipment **department of electromechanical *** -e * mail: -** e *** (received 1 december 2013; accepted abstact the wear behavior of alumina particulate reinforced process technique were investigated. a pin-on in composite samples at different grain size (1 µm of alumina respectively. mechanical properties characterization which strongly depends on microstructure properties of reinforcement revealed that the presence of hardness, ultimate tensile stress (uts), wear resistances. increases with the increase in the percentage of reinforcement of al wear rates of the composites were considerably less than that of the aluminum alloy percentage of reinforcement when compared to the base alloy a332. keywords: aluminium matrix composites, wear resistance, 1. introduction interest in developing metal matrix composites for use in high performance applications has increased significantly [1]. among these composites, aluminium alloy matrix composites attract much attention due to their lightness, high thermal conductivity, moderate casting temperature, etc.[2,3]. various hard ceramic particle materials such as sic, al2o3, mgo and b4c are used extensively to reinforce aluminium matrices. the superior properties of these materials such as high refractive index, h hardness, high compressive strength, wear resistance, etc. makes them suitable for use as reinforcement in matrices of composites khwarizmi engineering journal, vol. 10, no. 1, p.p. 6271(2014) on al 332 alloy matrixmicro -nano particles reinforced composite adnan dawood mohamed** rawnaq ahmed mohamed** machines and equipment engineering / university of technology electromechanical engineering / university of technology ***minstery of water resorce ibtihalnami@yahoo.commail: adnan.dawood.com@yahoo.commail: eroneq@yahoo.commail: -e *** december 2013; accepted 31 march 2014) the wear behavior of alumina particulate reinforced a332 aluminium alloy composites produced by a stir casting on-disc type apparatus was employed for determining the sliding wear rate 1 µm, 12µm, 50 nm) and different weight percentage (0.05 properties characterization which strongly depends on microstructure properties of ( nano , micro) alumina particulates lead to simultaneous increase in tensile stress (uts), wear resistances. the results revealed that uts, hardness, wear resistances increases with the increase in the percentage of reinforcement of al2o3 when compared to the base alloy a332 wear rates of the composites were considerably less than that of the aluminum alloy at all applied loads percentage of reinforcement when compared to the base alloy a332. aluminium matrix composites, wear resistance, micro -nano al2o3 particles. interest in developing metal matrix composites ons has ]. among these alloy matrix composites much attention due to their lightness, high conductivity, moderate casting various hard ceramic , mgo and aluminium matrices. the superior properties of these materials such as high refractive index, high hardness, high compressive strength, wear resistance, etc. makes them suitable for use as reinforcement in matrices of composites [4,5] normally, micro-ceramic particles are used to improve the hardness and ultimate strength metal. however, the ductility of the deteriorates with high ceramic particle concentration [6]. it is of interest to use nano sized ceramic particles to strengthen the matrix, while maintaining good ductility, high temperature creep resistance and [7,8]. a variety of methods for producing nano almcs have recently become available including mechanical alloying [9] ball milling sintering [11], etc. compared with other methods, melt processing which involves the stirring of ceramic particles into melts, has some important advantages such as better matrix-particle easier control of matrix structure, simplicity, low al-khwarizmi engineering journal nano al2o3 mohamed** alloy composites produced by a stir casting disc type apparatus was employed for determining the sliding wear rate (0.05-0.1-0.5-1) wt% properties characterization which strongly depends on microstructure properties of alumina particulates lead to simultaneous increase in the results revealed that uts, hardness, wear resistances when compared to the base alloy a332. the at all applied loads with increasing ceramic particles are used to improve the hardness and ultimate strength of the ductility of the almcs deteriorates with high ceramic particle ]. it is of interest to use nanosized ceramic particles to strengthen the metal matrix, while maintaining good ductility, high temperature creep resistance and better fatigue a variety of methods for producing nanobecome available including ball milling [10], nanoetc. compared with other methods, melt processing which involves the stirring of particles into melts, has some important particle bonding, control of matrix structure, simplicity, low mailto:ibtihalnami@yahoo.com mailto:adnan.dawood.com@yahoo.com mailto:eroneq@yahoo.com ibtihal a. mhmood al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 6271 (2014) 63 cost of processing and nearer net shape. wear is a common occurrence on most plant and machinery and is often a slow and progressive process, which may be accepted, as normal. however, if the rate of wear on particular machine component is high, so that it requires frequent repair and replacement, then it may constitute a wear problem. therefore, deciding whether a wear problem exists and requires attention calls for a degree of judgment of the circumstance. several researchers have worked on sliding wear mechanism of almcs reinforced with ceramic particulates like sicp, al2o3 and garnet particles etc, and have observed improvement in wear resistance [12,13]. a dry sliding wear test under the load 5-30 n, was conducted on aluminum composite. composites were prepared using stir casting method and reinforced with al2o3 particles by [14].they concluded that wear rate of composite and unreinforced alloy decreased with increasing load. wear rate decreased with increase in volume fraction and particle size 125 µm. the wear surface appearance showed plastic deformation at matrix alloy when the composites wear was caused by abrasions. the present study was conducted to evaluate the effect of the nano micro alumina particles on wear behaviour of a332 alloy and develop a fundamental understanding of the wear mechanisms and wear induced micro structural changes of alumina particle reinforced a332 alloy composite during dry sliding at different load and sliding distances. 2. experimental procedure 2.1. preparation of the composites a332 aluminium alloy and particulate alumina powder with size of (12 μm, 1 μm,50 nm) respectively, were used as the matrix and reinforcement phases the chemical composition for alloy fabricated chemical composition of the a332 alloy fabricated is listed in table. 1. composite specimens were manufactured by stir casting methods using mechanical mixing of the molten alloy. micro and nano-particles were heated at 1000 ◦c for 20 min and injected into the melt by using a stainless steel injection tube and inert argon gas in a graphite crucible inserted in a resistance heating furnace. the wet fraction of alumina powder injected into the composites were chosen (0.05-0.1-0.5-1) wt% micro-alumina and (0.05-0.1-0.5-1) wt% respectively nano -alumina. the stirring was continued for 15 min to produce homogenous mixture. . the speed of impeller was 400 rpm .stirring process was started 10 min before addition of reinforcement particles in the melt and continued 15 min after that. then, the stirrer was turned off and finally composite slurry was poured in a preheated cylindrical steel mould .the pouring temperature for the processes was 700 °c. the design of experimental rig is shown in fig. 1. fig. 1. design of experimental rig. ibtihal a. mhmood al-khwarizmi engineering journal, vol. 10, no. 1, p.p. table1, chemical composition (wt %) of the a332. alloys si% cu% fe% nominal chemical composition 8.5 10.5 2-4 1.2 a332 9.62 3.2 1.1 2.2. measurements and testing the density of the samples was measured by the archimedes’s method, while the theoretical densities calculated by taking the densities of a332 aluminium alloy and al2o3 particles were equal to 2.7 and 3.9 g/cm3, respectively. the porosity percentage in the materials was calculated according to the difference between the theoretical and measured density. to investigate the mechanical properties of the composites the brinell hardness values of the samples were measured on the polished samples using a ball with 5 mm diameter at a load of 250k tensile tests were carried out using instron machine according to astm.b 557, respectively. the cross head speed was set at 3 mm/min on the round specimens. each test was repeated two times to obtain a precise average value for each property. a pin-on-disc test apparatus was used to investigate the dry sliding wear characteristics of almmc as per astm g99-95 standards. the wear specimens (2×1) cm were machined, cylindrical in shape shown in fig.2. the initial weight of the specimen was measured in a single pan electronic weighing machine with a least count of 0.0001 g. during the test the pin was pressed against the counterpart rotating against en-32 steel disc by applying the load [5, 10, 15, 20, 25 and 30 n]. a strain–gauged friction detecting arm holds and loads the pin specimen vertically into a rotating hardened steel disc. after running through a time [5, 10, 15, 20, 25 min] period, the specimen were removed, cleaned with acetone, dried and weighed to determine the weight loss due to wear. the difference in the weight measured before and after the test gives the wear of the specimen. the wear rates were determined using the volumetric loss method. a schematic diagram for the pin-on-desk wear testing machine is shown in fig. 3. khwarizmi engineering journal, vol. 10, no. 1, p.p. 64 fe% mg% zn% mn% cr% ni% pb% 1.2 0.5-1.5 1 0.5 0.03 0.025 0.02 1.1 1.2 1 0.1 0.022 0.016 0,012 the density of the samples was measured by the archimedes’s method, while the theoretical densities calculated by taking the densities of particles were equal to 2.7 and 3.9 g/cm3, respectively. the porosity percentage in the materials was calculated according to the difference between the investigate the mechanical properties of the composites the brinell hardness values of the samples were measured on the polished samples using a ball kgf. the tensile tests were carried out using instron testing machine according to astm.b 557, respectively. the cross head speed was set at 3 mm/min on the round specimens. each test was repeated two times to obtain a precise average value for each disc test apparatus was used to ate the dry sliding wear characteristics of 95 standards. the machined, . the initial specimen was measured in a single th a least count of 0.0001 g. during the test the pin was pressed against the counterpart rotating against 32 steel disc by applying the load [5, 10, 15, gauged frictiondetecting arm holds and loads the pin specimen steel disc. after running through a time [5, 10, 15, 20, 25 and30 min] period, the specimen were removed, cleaned with acetone, dried and weighed to determine the weight loss due to wear. the difference in the sured before and after the test gives the wear of the specimen. the wear rates were determined using the volumetric loss method. a desk wear fig. 2. wear sample fig. 3. schematic diagram of pin testing machine. wear rates were calculated by the weight loss measurement. the formulae used to convert the weight loss to wear rate [16]: wr = δw / s …( where, wr: wear rate in (g/cm). khwarizmi engineering journal, vol. 10, no. 1, p.p. 6271 (2014) ti% al% 0.03 bal 0.036 bal wear sample. diagram of pin-on-disc wear wear rates were calculated by the weight loss measurement. the formulae used to convert the = δw / s …(1) ibtihal a. mhmood al-khwarizmi engineering journal, vol. 10, no. 1, p.p. δw: weight difference of the sample before and after each test in (gm) (δw=w1 w2). volumetric wear rate can be calculated as [16]: wv = wr / ρm where, wv: volumetric wear rate (cm3 /cm). ρm: density of pin (g/ cm3). pin-on-disc apparatus has a regulator of speed used to control or change the disc rotational speed, and a tachometer device to evaluate this speed practically. six rotational speeds were used, [50,100,150,200 , 250 and 300 r.p.m], that means six linear velocities of [0.392, 0.785, 1.178, 1.570 1.963 and 2.355 m/sec] were calculated respectively using the formula: v= 2π × r × n where: v: linear sliding speed (m/min). r: distance from the center of sample to the center of disc (0.075 m). n: disc rotational speed in r.p.m. total sliding distance was calculated as follows [16] s= v × t × 100 where: s: total sliding distance (cm). t: sliding time of running in minute . v: linear sliding speed (m/min). fig . 4. tensile test sample. 3. results and discussion 3.1. tensile strength the strength has prime importance engineering design such as yield strength, ultimate tensile strength and modu elasticity. the most of these properties determined by using astm standardized method.table. 2 shows mechanical properties of alloy 332 produced by casting. tensile strenght khwarizmi engineering journal, vol. 10, no. 1, p.p. 65 δw: weight difference of the sample before and volumetric wear rate can be calculated as [16]: …(2) disc apparatus has a regulator of speed used to control or change the disc rotational speed, and a tachometer device to evaluate this speed practically. six rotational speeds were used, 00 r.p.m], that means of [0.392, 0.785, 1.178, 1.570, ec] were calculated ...(3) r: distance from the center of sample to the center total sliding distance was calculated as follows ...(4) portance in strength, odulus of properties are standardized testing table. 2 shows mechanical properties of alloy 332 produced by casting. tensile strenght and elongation are recorded. after preparation a332 we compare it with nominal mechanical properties standard from [17]. figures 5, 6, 7, and 8 respectively display the tensile curves, yield strength and ultimate tensile strength of the composites, respectively. it could be noted that the flow curves do not show any sharp yield point irrespective of the material, and the strength values increase with the addition of micro al2o3 particles. it is believed that the great enhancement in tensile stress observed in these composites is due to good distribution of the nanoal2o3 particles and low degree of porosity, which leads to effective transfer of applied tensile load to the uniformly distributed strong al particulates. the grain reinforcement and strong multidirectional thermal stress at the al/ al interface are also important factors which play a significant role in the high strength of the composites. al2o3 particles have grain strengthening effect, which is improved with increasing weight percentage since they ac heterogeneous nucleation catalyst for aluminium [9−15].from the above the additives nanometer best composite in tensile strength is a332+1wt% al2o3 3.2. density and hardness the density of a332 and their composite were computed by massvolume relation and plotted against wt % of alumina. as shown in fig. 9. the variation in density decreases with an increase in weight percentage of alumina in the composite.also, according to the measured and theoretical densities of composite samples, it is revealed that the amount of porosity in the composite samples increases with increasing weight percentage of al2o3 decreasing the size of particles. fig.10 shows the results of micro hardness tests conducted on a332 alloy composite containing different weight percentage of al2 significant increase in hardness of the alloy matrix can be seen with addition of al higher value of hardness is clear indi fact that the presences of particulates in the matrix have improved the overall hardness of the composites. this is true due to the fact that aluminium is a soft material and the reinforced particle especially ceramics material being hard, contributes positively to the hardness of the composites. the presence of stiffer and harder al2o3reinforcement leads to the increase in constraint to plastic deformation of the matrix khwarizmi engineering journal, vol. 10, no. 1, p.p. 6271 (2014) after preparation a332 we compare it with nominal mechanical figures 5, 6, 7, and display the tensile curves, yield strength and ultimate tensile strength of the , respectively. it could be noted that curves do not show any sharp yield point irrespective of the material, and the strength s increase with the addition of nano and particles. it is believed that the great enhancement in tensile stress observed in these is due to good distribution of the particles and low degree of porosity, which leads to effective transfer of applied tensile load to the uniformly distributed strong al2o3 particulates. the grain reinforcement and strong al stress at the al/ al2o3 interface are also important factors which play a significant role in the high strength of the particles have grain-refined strengthening effect, which is improved with increasing weight percentage since they act as the heterogeneous nucleation catalyst for aluminium −15].from the above the additives additive 50 nanometer best composite in tensile strength is the density of a332 and their composite were volume relation and plotted against wt % of alumina. as shown in fig. 9. the variation in density decreases with an increase in weight percentage of alumina in the the measured and theoretical densities of composite samples, it is revealed that the amount of porosity in the composite samples increases with increasing particles and f micro hardness tests conducted on a332 alloy composite containing 2o3 particles.. a significant increase in hardness of the alloy matrix can be seen with addition of al2o3 particles. higher value of hardness is clear indication of the fact that the presences of particulates in the matrix have improved the overall hardness of the composites. this is true due to the fact that aluminium is a soft material and the reinforced particle especially ceramics material being hard, ntributes positively to the hardness of the composites. the presence of stiffer and harder reinforcement leads to the increase in constraint to plastic deformation of the matrix ibtihal a. mhmood al-khwarizmi engineering journal, vol. 10, no. 1, p.p. during the hardness test. thus increase of hardness of composites could be attributed to the relatively high hardness of al2o3 itself. as shown in fig. 10. the best composite in hardness is a332+1wt% al2o3 (50nano alumina). the percentage value of increasing hardness is 50% between 0.05 wt% to 1wt% (nano alumina), 37% between 0.05wt% to 1wt% (1 micron) and 25% between 0.05 wt % to 1 wt % (12 micron) as the same result with davious found hardness of the composites is increased with increase wt% of reinforcement [18]. 3.3. effect of time, load and sliding spee on wear characteristics as shown in figs. 11, 12, 13 the variation of wear rate (volumetric loss/min) with varying time, load and sliding speed for a332 aluminum alloy. the wear increases when the time is increasing but after 15 min the increasing of wear slowly so we choose time 15 min when load and sliding speed are constant. the wear increase when increasing load but after 15 n the increasing of wear slowly so we choose load 15 n when time and sliding speed are constant. the wear increase when increasing sliding speed but after 150 r.p.m the increasing of wear slowly so we choose speed 150 r,p.m when time and load are constant. 3.4. effect of reinforcement and particle size on wear rate dry sliding wear behavior of matrix alloy reinforced (0.05-0.1-0.5-1) wt% at different alumina particle size (50 nm, 1 μm, 12 respectively as shown in fig. 14 reasonable increase in wear resistance. it is observed that addition of different (0.05-0.1-0.5-1) wt% nano khwarizmi engineering journal, vol. 10, no. 1, p.p. 66 during the hardness test. thus increase of e attributed to the itself. as shown the best composite in hardness is (50nano alumina). the percentage value of increasing hardness is 50% alumina), 37% micron) and 25% % to 1 wt % (12 micron) as the hardness of the composites is increased with increase wt% of effect of time, load and sliding speed as shown in figs. 11, 12, 13 the variation of wear rate (volumetric loss/min) with varying time, load and sliding speed for a332 aluminum alloy. the wear increases when the time is increasing ar slowly so we choose time 15 min when load and sliding speed are constant. the wear increase when increasing load but after 15 n the increasing of wear slowly so we choose load 15 n when time and sliding speed are constant. the wear increase ing sliding speed but after 150 r.p.m the increasing of wear slowly so we choose speed 150 r,p.m when time and load are constant. and particle dry sliding wear behavior of matrix alloy 1) wt% at different , 12 μm) as shown in fig. 14 reasonable increase in wear resistance. it is observed that 1) wt% nanomicro alumina particle size shows lesser wear rate than the base alloy. and shown the highest wear rate is distinct for matrix alloy and linearly the wear rate decreased by increasing the percentage of reinforcements. the maximum wear resistance of the composites is considerably imp the addition of 1 % nano alumina particle. fig. 5. stress-strain diagram of a332 fabricated. 4. conclusion 1. it was revealed that the hardness of composite samples increased with increasing the weight percentage of al2o3 particles. 2. strength of prepared composites both tensile and yield was higher in case of composites, while ductility of composites was less when compared to as cast 332 al. further, with increasing wt% of al2o3, the tensile strength shows an increasing trend. 3. the maximum wear resistance at 1% nano alumina. khwarizmi engineering journal, vol. 10, no. 1, p.p. 6271 (2014) shows lesser wear rate than the base alloy. and shown the highest wear rate is distinct for matrix alloy and linearly the wear rate decreased by increasing the percentage of reinforcements. the maximum wear resistance of the composites is considerably improved due to the addition of 1 % nano alumina particle. strain diagram of a332 fabricated. it was revealed that the hardness of composite samples increased with increasing the weight strength of prepared composites both tensile and yield was higher in case of composites, while ductility of composites was less when compared to as cast 332 al. further, with , the tensile strength imum wear resistance at 1% nano ibtihal a. mhmood al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 6271 (2014) 67 fig . 6. tensile strength and elongation for12 micron. fig . 7. tensile strength and elongation for1 µm grain size. fig. 8. tensile strength and elongation for nano composite. ٠ ٠.٥ ١ ١.٥ ٢ ٢.٥ ٣ ٣.٥ ٢٤٨ ٢٥٠ ٢٥٢ ٢٥٤ ٢٥٦ ٢٥٨ ٢٦٠ ٢٦٢ ٢٦٤ ٢٦٦ ٢٦٨ ٢٧٠ ٠ ٠.٥ ١ ١.٥ el on ga tio n% te ns ile s tr en gt h t(mp a) alumina reinforced wt% tensile strength elongation% ٠ ٠.٥ ١ ١.٥ ٢ ٢.٥ ٣ ٣.٥ ٤ ٤.٥ ٢٤٥ ٢٥٠ ٢٥٥ ٢٦٠ ٢٦٥ ٢٧٠ ٢٧٥ ٠ ٠.٥ ١ ١.٥ el on ga tio n% te ns ile s tr en gt h t(m pa ) alumina reinforced wt% tensile strength elongation% ٠ ٠.٥ ١ ١.٥ ٢ ٢.٥ ٣ ٣.٥ ٤ ٤.٥ ٥ ٢٤٥ ٢٥٠ ٢٥٥ ٢٦٠ ٢٦٥ ٢٧٠ ٢٧٥ ٢٨٠ ٢٨٥ ٠ ٠.٥ ١ ١.٥ el on ga tio n% te ns ile s tr en gt h t(mp a) alumina reinforced wt% tensile strength elongation% ibtihal a. mhmood al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 6271 (2014) 68 fig . 9 . density for composite. fig . 10. hardness for composite. fig. 11. effect of time on wear ratea332. ٢.٥٨ ٢.٦ ٢.٦٢ ٢.٦٤ ٢.٦٦ ٢.٦٨ ٢.٧ ٢.٧٢ ٠ ٠.٥ ١ ١.٥ de ns ity (g /c m ^3 ) alumina reinforced wt% ١٢micron ١micron nano ٠ ٢٠ ٤٠ ٦٠ ٨٠ ١٠٠ ١٢٠ ١٤٠ ٠ ٠.٥ ١ ١.٥ ha rd ne ss (k gf /m m ^2 ) alumina reinforced wt% ١٢micron ١micron nano ٠ ٢ ٤ ٦ ٨ ١٠ ١٢ ٠ ٥ ١٠ ١٥ ٢٠ ٢٥ ٣٠ ٣٥w ea r v ol um *1 0^ -8 (c m ^3 /c m ) time(min) ibtihal a. mhmood al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 6271 (2014) 69 fig. 12. effect of load on wear ratea332. fig. 13. effect of sliding speed on wear ratea332. fig. 14. wear rate for composite. ٠ ٠.٠٠١ ٠.٠٠٢ ٠.٠٠٣ ٠.٠٠٤ ٠.٠٠٥ ٠.٠٠٦ ٠.٠٠٧ ٠.٠٠٨ ٠.٠٠٩ ٠.٠١ ٠ ١٠ ٢٠ ٣٠ ٤٠ w ea r v ol um (c m ^3 /c m ) load (n) ٠ ٠.٥ ١ ١.٥ ٢ ٢.٥ ٣ ٠ ٥٠ ١٠٠ ١٥٠ ٢٠٠ ٢٥٠ ٣٠٠ ٣٥٠w ea r v ol um *1 0^ -7 (c m ^3 /c m ) sliding speed r.p.m ٠ ٠.٥ ١ ١.٥ ٢ ٢.٥ ٣ ٣.٥ ٠ ٠.٥ ١ ١.٥ w ea r r at e (c m ^/ cm )* 10 ^8 alumina reinforced wt% ١٢micron ١micron nano ibtihal a. mhmood al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 6271 (2014) 70 table 2, properties of standard and fabricated a332 [17]. property material tensile strength(mpa) t yield strength(mpa) y (0.2%) elongation % nominal a 332 248 193 1 fabricated a332 250 195 1.5 5. refrences [1] hatch g.e., aluminum, in: properties and physical metallurgy, asm international,metals park, oh, 1984:pp 3035. [2] hull d., an introduction to composite material, second ed., mcgraw-hill, new york, 1981:pp 196-252. [3] smith w.f., principles of materials and engineering, mcgraw-hill, new york, 1996. [4] hassan s.b., aponbiede o. and aigbodion v.s., effect of particle size, forging and ageing on the mechanical fatigue characteristics of al2o3/sicp metal matrix composites, j. alloys compd., 2008;466: pp268-272. [5] zhang s., zhao y., chen g. and cheng x., (al2o3 + al3zr)/a356 nanocomposites fabricated by magnetochemistry in situreaction, j. alloys compd., 2009; 475:pp261-267. [6] sahin y., kok m. and celik h., toolwear and surface roughness of al2o3 particlereinforced aluminium alloycomposites, j. mater. process. technol.,2002; 128: 280291. [7] chou s., huang j., lii d. and lu h.,the mechanical properties of al2o3/aluminum alloy a356 composite manufactured by squeeze casting, j.alloys compd., 2006; 419: 98-102. [8] shorowordi k.m., laoui t., haseeba.s.m.a., celis j.p. and froyen l.,microstructure and interface characteristics of b4c, sic and al2o3reinforced al matrix composites: acomparative study, j. mater. process.technol., 2003; 142:pp 738-743. [9] k. akio, o. atsushi, k. toshiro and t. hiroyuki. j. jpn. inst. light met. 49 (1999), pp. 149–154. [10] k.m. mussert, w.p. vellinga, a. bakker and s. van der zwaag. j. mater. sci. 37(2002), pp. [11] d.m. lee, b.k. suh, b.g. kim, j.s. lee and c.h. lee, mater. sci. technol. 13 (1997), p. 590. [12] v. laurent, p. jarry, g. regazzoni and d. apelian, j. mater. sci. 27 (1992), p. 447 [13] r.a. saravanan and m.k. surappa, mater. sci. eng. a276 (2000), p. 108. [14] huseyin sevik, s.can kurnaz, “properties of α alumina particulate reinforced aluminum alloy produced by pressure die casting” materials and design 27(2006) pp, 676-683. [15] kok m “ abrasive wear of al2o3 particles reinforced 2024 aluminum alloy composite fabricated by veretex method"composite part a37,(2006),pp457464. [16] a.kr ishnan, s. m. achary, “wear behavior investigations of journal bearing materials”, 10thnational conference on technological trends, (nctt09), 2009, pp 20-25. [17] g. f. vander voort, " metallography and microstructures”, asm handbook committee ,volum9 , 2004. [18] davis, l. w., bradstreet, s. w. a study of wear behaviour of matrix metal composites wear 113 1970:pp. 234 – 239. )2014( 6271 صفحة ،1العدد ،10دالمجل الھندسیة الخوارزمي مجلةابتھال عبد الرزاق محمود 71 دقائق سیرامیكیة ونانویة من االلومیناب المقواة a332تحسین مقاومة البلیان لسبیكة االلمنیوم ***رونق احمد محمد ** عدنان داود محمد *ابتھال عبد الرزاق محمود الجامعة التكنولوجیة/ المكائن والمعدات قسم ھندسة * الجامعة التكنولوجیة/ قسم الھندسة الكھرومیكانیكیة ** وزارة الموارد المائیة*** ibtihalnami@yahoo.com:البرید االلكتروني* adnan.dawood.com@yahoo.com:البرید االلكتروني** eroneq@yahoo.com:البرید االلكتروني*** الخالصة و بنسب وزنیة ) نانومتر ٥٠ ،مایكرون ١ ،مایكرون ١٢(مدعمة بدقائق سیرامیكیة من االلومینا وباحجام مختلفة a332 ان سلوك البلیان لسبیكة المنیوم ان خصائص المواصفات المیكانیكیة تعتمد على توزیع .احتسبت وباستعمال جھاز فحص العینات وباستخدام تقنیة السباكة ) % ١ ،٠,٥ ،٠,١ ، ٠,٠٥(مختلفة .یان تزداد بزیادة نسبة االلومیناوالمایكرویة ، فھذا التوزیع ادى الى تحسن الصالدة وواجھاد الشد االعلى ومقاومة البلیان حیث ان مقاومة البلالدقائق النانویة .لیةان معدل البلیان للمتراكبات یعتبر اقل من سبائك االلمنیوم تحت تاثیر نفس الحمل مع زیادة نسبة االلومینا مقارنة بالسبیكة االص mailto:ibtihalnami@yahoo.com mailto:adnan.dawood.com@yahoo.com mailto:eroneq@yahoo.com (microsoft word \335\341\307\315 \335\307\316\32141-49) al-khwarizmi engineering journal al-khwarizmi engineering journal,vol. 13, no. 4, p.p. 4149 (2017) enhancement of heat exchanger performance by using dimpled tube falah f. al-jabery department of mechanical engineering/ university of technology email: falahatem59@ yahoo.com (received 9 february 2017; accepted 14 may 2017) https://doi.org/10.22153/kej.2017.05.002 abstract the enhancement of heat exchanger performance was investigated using dimpled tubes tested at different reynolds numbers, in the present work four types of dimpled tubes with a specified configuration manufactured, tested and then compared performance with the smooth tube and other passive techniques performance. two dimpled arrangements along the tube were investigated, these are inline and staggered at constant pitch ratio x/d=4, the test results showed that nusselts number (heat transfer) of the staggered array is higher than the inline array by 13%. the effect of different depths of the dimple (14.5 mm and 18.5 mm) has been also investigated; a tube with large dimple diameter enhanced the nusselts number by about 25% for the range of reynolds number between 400020000. the overall enhancement ratio was used to differentiate the passive technique and comparison of different configurations for the technique itself, the result depicted that the 10 mm dimple diameter with a pitch ratio of x/d= 4 gives better performance than the static mixer and twisted tape techniques. the overall enhancement ratio of the 10 mm dimple diameter is varied from (1.21 to 1.65) that means good performance for a range of reynolds numbers (4000-20000). this indicates that 2165 % of heat transfer area can be saved at the same pumping power compared with the smooth tube heat exchanger. keywords: dimple tube, heat transfer coefficient, nusselts number, friction factor. 1. introduction the techniques used in enhance the performance of heat exchangers can be classified into two main categories, passive and active techniques, in addition to a hybrid technique which includes two or more from each of passive and active technique [1]. a great deal of research has focused on various augmentation techniques with emphasis on rough surfaces, spiral ribs, transverse grooves, corrugated and spirally corrugated tubes, straight fins, and spiral and annular fins. in this investigation, augmented surface has been achieved with dimples strategically located in a pattern along the tube of a double-pipe heat exchanger with the increased area on the tube side. augmented surfaces can create one or more combinations of the following conditions that are favourable for increasing the heat transfer coefficient with a consequent increase in the friction factor due to firstly the interruption of the development of the boundary layer and increase of the degree of turbulence, secondly the effective heat transfer area increased, and finally the generation of rotating and/or secondary flows. kumar & murugesan [2] considered and evaluated the heat transfer and pressure drop investigations of more than thirty published work from (2001 to 2012) of various twisted tapes placed in heat exchangers. the results showed that for modified twisted tape geometry, the heat transfer rate is higher with reasonable friction factor for both laminar and turbulent flow. m. udaya kumar et al. [3] reviewed the heat transfer enhancement techniques in square ducts of more than ten published works from years (2004 to 2013). they found that the heat transfer of square ducts was found considerably higher than the circular tube. this is mainly because the square duct has a high surface to volume ratio. the short length twisted tape in square and rectangular ducts performs worse than the full length twisted tape. however, falah f. al-jabe al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 4149 (2017) 42 regularly spaced twisted tapes perform significantly better than the full length twisted tapes. watcharin et al.[4] studied experimentally the influences of the twisted tape insertion on the heat transfer and flow friction characteristics in a concentric double pipe heat exchanger. p. murugesan et al. [5] investigated experimentally the heat transfer and friction factor characteristics of a circular tube fitted with plain twisted tapes and u–cut twisted tapes. chinaruk thianpong et al [6] performed an experimental study of fully developed turbulent flow in a dimpled tube in conjunction with a twisted tape. khalil et. al. [7] investigated experimentally the heat transfer, pressure drop characteristics and efficiency enhancement for swirling flow through a sudden pipe expansion. p. promvonge [8] conducted a set of experiments by inserting several conical rings as tabulators over a test tube. all the available enhancement techniques shown by the literature were mainly effective on heat transfer at the tube side. with some applications, the tube shape had a dual effect on both sides with a great penalty of the pressure drop on both sides. on the other hand, most of the enhancement devices depicted in the literature required addition of materials that impact on manufacturing cost while in the present proposed tube, no additional materials will be used. there is a shortage of the available data in the literature for the effect for dimpled tube geometrical parameters on the heat transfer and pressure drop in turbulent flow. the present work will cover the main geometrical parameters, such as dimple arrangement (staggered, inline), dimple diameter, and numbers of dimples. the relationship between the thermal and hydraulic performance must also be considered, by means of the overall enhancement ratio concept. 1. experimental equipment and data reduction the schematic diagram and photo of test rig used in this study is shown in figure (1), the test rig consists of an arrangement of force convection open loop flow system. this system contains air blower, piping, instrumentation and test section. the blower is connected to a carbon steel pipe of 50 mm diameter and 2 m length. orifice plate intermediates this pipe is to measure the air flow rate through the system. two pressure taps were placed upstream and downstream the orifice flange to measure the pressure difference, using water manometer. temperature tap located upstream of orifice plate was used for measuring the air blowing temperature. to achieve a fully developed flow at the test section entrance, a tube with 1m length having the same test tube diameter been connected with the test tube by a special coupling. the test section is one of the main components in an experimental test facility which consisted of a tube in tube heat exchanger in cross flow configuration. the test section contains a tube of 35 mm diameter surrounded by a jacket pipe of 75 mm inner diameter with 1m long, and is insulated by 5 cm rock wool. in the present work, a constant wall temperature technique was used by applying saturated steam on the outer wall of test tube. the condensation heat transfer coefficients are approximately 100 times greater than the air convective heat transfer inside the tube, therefore the wall temperature will be more likely equal to the condensation temperature. this means that no set of thermocouples is required to be placed on the tube wall. the steam is supplied from a boiler available at the laboratory, and pressure regulator valve was used to obtain constant saturated steam pressure and temperature at annulus of test tube. the jacket is instrumented with pressure, temperature gauge, drain and vent valve to get rid of the non-condensable gases and to drain the condensate steam during the test period. temperature and pressure taps are placed at the inlet and the exit of the test tube to measure the temperature and pressure of air across the tested section. the test section is a shell and tube configuration, where steam flows.in shell side, while air flows inside the tube. the shell side is made from carbon steel tube of 75 mm inner diameter, outer diameter 82 mm and 1200 mm length. the shell ends are welded with the special flange that machined to produce sealing housing, where sealing cap can be pushed through by screw bolts. the flanges have a central bore hole with a diameter equals to the test tube diameter, where the test tube can be slide through aligning the tube to be in the shell center. teflon rope of 10 mm is packed in the flange housing and warped round the test tube, while sealing cup is forced by the four bolts to compress the teflon rope on the test tube and on the inner ring of the flange housing to produce tight sealing and to maintain the saturation steam pressure and temperature. the shell is insulated by falah f. al-jabe al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 4149 (2017) 43 fiber glass of 76 mm thickness. five holes of (13 mm) are drilled on the shell surface to connect the following apparatus: • steam valve of ½ inch. • pressure gage: rang of 0-10 bar with increments of 0.2 bar. • condensate drain valve size ½ inch. • vent valve size ½ inch. • thermocouple well. fig. 1. schematic diagram and photo of the test rig. 2.1. dimpled tube all types of dimpled tubes manufactured from copper of (1600 mm) length and inner diameter of 35 mm, shown in figure (2), were examined in the present work, also a smooth tube of (35 mm) inner diameter and (1600 mm) was used as a reference tube. the geometrical parameters, dimpled arrangement and dimensions of all dimple tubes are specified in table (1) and figure (2). manufacturing process was developed to obtain these tubes using a cnc machine to obtain dimples with a specified configuration. fig. 2. geometrical figure and photo of dimple tubes. table 1, test tubes configurations. 2.2. data acquisition the main object of the present experimental work is to evaluate the convective heat transfer coefficient then nasselts number and pressure drop across the tested tubes. according to the first law .of thermodynamic for incompressible flow with constant specific heat, the heat transfer to the air can be calculated: q� � �� � cp� t� �� � t� ��� … 1� the volume and the mass flow rate through the orifice plat are evaluated by measuring the pressure drop across the orifice, the upstream temperature and using the following equations [9]: v� � c� e a� �� �� �� … 2� where, cd is the discharge coefficient, ao is the cross-sectional area of the orifice plat, δp is the pressure drop across the orifice plat and e is the velocity approach coefficient.[9,10] c� � 0.5959 # 0.0312β�.& � 0.184β) # 0.0029β�.* +10, re�/ 0.1* # 0.09l&β3 1 � β3�4& � 0.0337l�β6 … 3� e � 1 � β3�4&/� … 4� dimpled arrangement distribution angle d mm x mm d/d x/d no. of dimples inline pipe 60 10 40 0.285 4 174 staggered pipe 60 10 40 0.285 4 162 staggered pipe 120 14.5 58 0.414 4 63 staggered pipe 120 18.5 74 0.529 4 48 falah f. al-jabe al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 4149 (2017) 44 where, β .is the orifice to tube diameter (d/d),and l1 & l2 are constant [10]. the mass flow rate is calculated from the following equation: �� � � v� ρ� … 5� in the heat transfer and fluid flow, it is essential to know the flow regime whether it is laminar, or turbulent ,which can be represented by the dimensionless parameter known as reynolds number used as criterion, and re should be greater than 4000 for turbulent flow. re9 � ρ u d μ … 6� the air density ρ and the dynamic viscosity µ are evaluated based on the air bulk temperature. the air velocity through the test tube can be calculated from continuity equation: u � �� �π4 d� ρ … 7� to express the convective heat transfer from the tube wall to the air, the newton’s law for cooling is applied. [11] q? � h� a? t? � ta� … 8� the system is thermally balanced q? � q��, i.e, the heat gained by the air is the heat released by the tube wall. by combining equations (1) and (8), the convective heat transfer coefficient can be evaluated. h� � �� � cp� t�� � t��� a? t?� � ta� … 9� where, tb. is the bulk air temperature and can be evaluated as follow: ta � t�� # t�� 2 … 10� the inner wall temperature twi, can be evaluated from the measured heat flow through the test tube and the saturation steam temperature using the following equation: [12] q � � c d efgehi� jk lmn mio p q r s mn tu … 11� where hc , .is the condensation heat transfer coefficient on the horizontal tube and can be calculated from the following equation:[12] hv � 0.725 +ρw ρw � ρx� g hz[ k6 μw d� t] � t?�� / 0.�* … 12� heat transfer represented by dimensionless parameter nussalts number.is calculated by the following equation:[12] nu � h� d k� … 13� to validate the present experimental test apparatus, the test was performed on a smooth tube and then results compared with well-known equations of dittus-boelter, and blasins equation for heat transfer and friction factor inside a tube for a turbulent flow at constant wall temperature [13]. nu � 0.023 r`0.) pb0.6 … 14� nu � 0.012 re0.)1 � 280�pr0.3 … (15) f = 0.6&, d`e.fg … (16) the friction factor (f) can be calculated by measuring the pressure upstream and downstream of the tested tube and according to the equation:[12] f � 2 ∆p d l ρ u� … 17� δp represents the pressure drop across the test section and is evaluated from the following equation:[9] ∆p � ρ g h … 18� the data obtained from the smooth tube were compared with blasins equation for smooth pipe, and the results are presented. the overall enhancement ratio is defined as the ratio of heat transfer enhancement ratio to the friction factor ratio; this parameter was derived according to using same pumping power for different configurations. [14]. k � lmno mnpq lro rpqs.t ≥ v … vw� x 2. results and discussion the experimental investigation imposes a study of dimpled arrangement (staggered, inline), dimple diameter, and number of dimples. the relationship between the thermal and hydraulic performance must also be considered. heat transfer and pressure drop for all test tubes were evaluated and presented as a dimensionless value by nusselts number and friction factor in the range of reynolds number from 4000 to 20000. the overall enhancement ratio (y� of dimpled tube compared with others passive techniques were discussed. 3.1. verification of smooth tube results in order to verify the experimental results obtained from the present test facility for heat transfer and pressure drop, experimental tests were performed on a smooth tube of 1.6 m length (1.2 m in test section). the experimental results were compared with the results obtained by the wellknown correlations under a similar condition to falah f. al-jabe al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 4149 (2017) 45 evaluate the validity of the smooth tube. comparison of nusselt number is shown in figure (3). obviously, the experimental results of heat transfer are in good agreement with empirical correlations developed by dittus–boelter [13]. it is noted that the average deviation in nusselts number was approximately of 5%, and the maximum deviation of 13%. comparison of the friction factor (f) of present plain tube and the results obtained by blasins correlation [13] is shown in figure (4), this figure shows the apparent deviation is in the range of reynolds number. this was attributed to the pipe surface roughness. in the present work, the experimental data obtained from the smooth tube will be used as a reference for comparison with a dimpled tube, since all tested tubes are made from the same materials (copper) and same manufacturing process. the following subsections will discuss the effect of the geometrical parameters on nusselts number and friction factor. the comparison criteria of overall enhancement ratio for different types of dimpled tube will be discussed: fig. 3. comparison of heat transfer of present experimental test of smooth tube with published empirical equations [13]. fig. 4. comparison of friction factor of the present test smooth tube with published blasins equation [13]. 3.2. effect of dimples arrangement two dimpled arrangements along the tube were investigated, these are inline and staggered at constant pitch ratio x/d=4, all with approximately the same number of dimples, as shown in table (1). the test results presented in figure (5) show that the heat transfer of the staggered array is higher than the inline array by 13%. this is due to more turbulence intensity and strong vortex formation induced in inline arrangement tube. it is clear that the nusselts number increases with increasing reynolds number as for the conventional turbulent flow in tube of approximately the same trend. fig. 5. effect of dimple arrangement on heat transfer. falah f. al-jabe al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 4149 (2017) 46 3.3. effect of dimples diameter from the test results presented in figure (6) the effect of different depths of the dimple (14.5 mm and 18.5 mm), tube with 18.5 mm dimple diameter enhanced the nusselts number by 25% compared with the tube of 14.5 mm dimple diameter for the range of reynolds number between 400020000,this due to first, large dimple diameter makes the kinetic energy of the core flow dominant and much higher than the shear force induced by the dimpled surface. second, the dimple depths is small, and the secondary flow is still within the limited space of the wall surface therefore, in the present case, different depths of the dimple (14.5 mm and 18.5 mm) caused increasing in mixing between the secondary and core flow, the local heat transfer on tube wall will be improved. fig. 6. effect of dimple diameter on heat transfer. 2.4. comparison with other augmented surfaces the overall enhancement ratio is used to differentiate the passive technique and comparison of different configurations for the technique itself. the overall enhancement ratio given in equation (19) is relation was based on the heat transfer and pressure drop of smooth tube; this parameter was derived according to using same pumping power for different configurations.[14] according to this relation, the overall enhancement ratio should be greater than unit. the greater value indicates better performance for that geometry, while values less than one indicate bad or worthless approach, also this parameter overcomes the friction factor variation. figure (7) shows the comparison of the overall enhancement ratio for a present dimpled tube shape with staggered arrangements. the result depicted that the 10 mm dimple diameter with a pitch ratio of x/d= 4 gives better performance than the other techniques. the enhancement ratio of the 10 mm dimple diameter is varied from (1.21to1.65) for a range of reynolds numbers (4000-20000). this indicates that 21-65 % of heat transfer area can be saved at the same pumping power compared with the smooth tube heat exchanger. the results showed that the 10 mm dimple diameter tube with a pitch ratio of x/d= 4 gives better performance than other passive techniques such as twisted tap and static mixer. fig. 7. comparison of the overall enhancement ratio of the present dimple tube with other passive technique 3. conclusions an experimental study of fully developed turbulent flow in a spherical dimpled tube has been done. the influences of the dimpled arrangements and dimple diameter on the heat transfer rate and friction factor characteristics have also been investigated, and the following points can by highlighted: a. staggered arrangement of dimpled tube manifested better enhancement of heat transfer by 13% than inline arrangement at same dimples pitch ratio. at the same time, higher friction factors were recorded for staggered arrangement. falah f. al-jabe al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 4149 (2017) 47 b. the large dimple diameter enhanced the nusselts number by 25% compared with the small dimple diameter. c. the heat-transfer coefficients of the enhanced dimpled tubes are a lot higher than the conventional smooth tubes and give only marginal drops in pressure. an important reason for the heat-transfer enhancement of the enhanced tubes is the modified rough surface, which causes increases in the turbulence mixing intensity in the flow field, and also by restricting the development of fluid boundary layers close to the heat transfer surfaces, which contributes to increases in heat-transfer operation. d. the overall enhancement ratio of the 10 mm dimple diameter is varied from (1.21to1.65) for a range of reynolds numbers (4000-20000) compared with the static mixer and twisted tape. notation latin characters character description units a tube surface area m2 cd discharge coefficient cp specific heat at constant pressure kj/kg k d tube diameter m d dimple diameter m f friction factor h head m h convection heat transfer coefficient w/m2 k l tube length m �� mass flow rate kg/s nu nusselt number re reynolds number t temperature k u velocity m/s p pressure n/m2 greek symbols character description units ρ fluid density kg/m3 µ dynamic viscosity kg/m.s β orifice to tube diameter ratio subscripts symbol title a air b bulk s steam 4. references [1] p. bharadwaj, a.d. khondge,and a.w. date, heat transfer and pressure drop in a spirally grooved tube with twisted tape insert, proceeding of the international journal of heat and mass transfer 52(2009) pp.19381944. [2] c. nithiyesh kumar, p. murugesan,” review on twisted tapes heat transfer enhancement”, international journal of scientific & engineering research, vol. 3, issue 4, april-2012. [3] m. udaya kumar, m. manzoor hussian,and md. yousaf ali,” review of heat transfer enhancement techniques in square ducts with inserts” ,international journal of emerging technology and advanced engineering, vol’ 3, issue 8, august 2013. [4] watcharin noothong, smith eiamsa-ard, and pongjet promvonge,” effect of twisted-tape inserts on heat transfer in a tube”, the 2nd joint international conference on “sustainable energy and environment (see 2006)”, 21-23 november 2006, bangkok, thailand. [5] p. murugesan, k. mayilsamy,and s. sures,” heat transfer and friction factor in a tube equipped with u-cut twisted tape insert”. jjmie, vol. 5, number 6, pp. 559 – 565, dec.2011. [6] chinaruk thianpong, petpices eiamsa-ard, khwanchit wongcharee, and smith eiamsaard,|” compound heat transfer enhancement of a dimpled tube with a twisted tape swirl generator” international communications in heat and mass transfer 36, pp. 698– 704,2009. [7] a. khalil, a. e. zohir and a. m. farid,” heat transfer characteristics and friction of turbulent swirling air flow through abrupt expansion”, american journal of scientific and industrial research, 1(2):pp. 364-374, 2010. [8] promvonge, p., “heat transfer behaviors in round tube with conical ring inserts”, energy conversation management, 2007. falah f. al-jabe al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 4149 (2017) 48 [9] m .r. jafari nasr, g. t. polley, and a. t. zoghi, "performance evaluation of heat transfer enhancement", chisa, praque, 2002. [10] bs1042 standard,”method of measurement of fluid in closed conduits”, psrt 1,section 1.1,1981. [11] r. l. webb, and n. hyun kim, “principles of enhanced heat transfer”, second edition, taylor francis group, 2005. [12] m. r. jafari nasr, a. t. zoghi, and h. r. khakadaman,”performance evaluation of heat transfer enhancement in heat exchanger design, tahghigh, n 43, 2002. [13] j. p. holman, "heat transfer ", tenth edition, department of mechanical engineering southern methodist university (2010). [14] ghinwa sami almamir, “experimental and numerical investigation of heat transfer enhancement for dimple tube” m.sc. thesis submitted to university of technology mechanical engineering department, 2014. )2017(49-41 ، صفحة4د، العد13دجلة الخوارزمي الهندسية المجلم فالح فاخر حاتم 49 باستخدام االنابيب المندبة تحسين اداء المبادل الحراري فالح فاخر حاتم الجابري الجامعة التكنولوجية / قسم الهندسة الميكانيكية yahoo.com alahhatem59f@البريد االلكتروني الخالصة واختبارها اربع نماذج مختلفة االشكال وتم لهذا الغرض تصنيع ةدبتم في هذا البحث دراسة تحسين اداء المبادالت الحرارية باستخدام االنابيب المن ان ئج العمليةالنتا بينت (x/d=4)تمت دراسة تاثير ترتيب الندب على طول االنبوب ( متناظر , متخالف) عند ها الحراري مع االنبوب االملس. ئادا ةومقارن كذلك تم دراسة تاثير قطر الندبة من االنابيب متناظرة الندب. %١٣عدد نصلت) لالنابيب متخالفة الندب اكبر ب (معدل انتقال الحرارة )14.5mm,18.5mm عند استخدام انبوب بقطر كبير لمدى عدد رينولدز يتراوح %٢٥تحسن عدد نصلت وبالتالي انتقال الحرارة بنسبة ) واظهرت النتائج استخدمت نسبة التحسين الكلية للمقارنة بين التقنية الحالية والتقنيات السلبية المستخدمة في تحسين اداء المبادالت الحرارية وكذلك . ٢٠٠٠٠-٤٠٠٠بين المختلفة السلبية االساليبتعطي اداء افضل من x/d=4وخطوة 10mmبقطر الندب الية اظهرت النتائج ان االنبوب ذاذج البحث الحاللمقارنة بين نم ط وكذلك من اسلوب استخدام االجزاء لتحسين االداء وكانت النتائج تشير الى ان االنابيب المزودة بالندب المتخالفة تعطي اداء افضل من اسلوب استخدام الخّال ً حرارييعني اداء هذاو ١٫٦٥الى ١٫٢١ نسبة التحسين الكلية بين تراوح. تالملتوية ً تخفيضاي ٢٠٠٠٠-٤٠٠٠ عدد رينولدز يامدعند اً جيد ا مساحة في ا مقارنة مع استخدام االنبوب االملس.نفسها قدرة الضخ ل %٦٥-٢١انتقال الحرارة بنسبة al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 3344 (2014) experimental study of the effect of exhaust gas recirculation (egr) and injection timing on emitted emissions at idle period miqdam tariq chaichan department of machines and equipments engineering/ university of technology e. mail: miqdam_tc@uotechnology.edu.iq (received 26 june 2014; accepted 22 october 2014) abstract heavy-duty diesel vehicle idling consumes fossil fuel and reduces atmospheric quality at idle period, but its restriction cannot simply be proscribed. a comprehensive tailpipe emissions database to describe idling impacts is not yet available. this paper presents a substantial data set that incorporates results from di multi-cylinders fiat diesel engine. idle emissions of co, hydrocarbon (hc), oxides of nitrogen (nox), smoke opacity, carbon dioxide (co2) and noise have been reported, when three egr ratios (10, 20 and 30%) were added to suction manifold. co2 concentrations increased with increasing idle time and engine idle speed, but it didn’t show clear effect for it advancing. co concentrations increased for all the studied tests with adding egr. hc concentration increased with idle time advance, but it reduced with increasing idle speed and advancing engine it. nox concentrations reduced with adding egr for all the tested variables. nox increased with increasing idle time, engine speed and advancing it. smoke opacity increased with increasing idle time and retarding it. using egr increased opacity for all tested cases. egr addition reduced engine noise for all tested cases. engine noise increased with increasing idle time and retarding it. keywords: engine idling, idle time, injection timing, egr, nox, pm, hc co, noise, smoke opacity. 1. introduction today the diesel engine is the power source with the lowest specific fuel consumption and is essential in the global reduction of carbon dioxide emissions. the success of the diesel engine is due to a precisely controlled combustion process and high technology exhaust after treatment. this combination yields very low fuel consumption combined with the lowest possible emissions. but diesel engines still have some problems especially in cold start, warm-up and idle regions [1 & 2]. in iraq, diesel engines are used very highly as long-haul trucks, buses, mini buses, trains, constructing machines and electrical generators. most of these engines typically spend a substantial percentage of time idling while the driver takes mandatory rest periods (i.e., hours of driving and rest, at control and checking points or at traffics). that amount of time varies considerably. drivers may allow their engines to idle for a variety of reasons and under many different circumstances. lutsey [3] found climate control to be the most common reason cited by drivers for idling, and use of accessories and concerns about start-up were also cited. on-duty drivers of both longand short-haul trucks may also tend to idle their engines during the workday while waiting to load or unload or while sitting in traffic, or they may idle their engines for other reasons related to their work or to vehicle operation and maintenance [4 & 5]. drivers of long-haul trucks often live in these trucks for days, sometimes weeks, at a time as they deliver these goods. when stopped overnight, many of these drivers leave their engines idling to heat or air-condition their cabs and produce power for the amenities they need to carry on their lives while on the road [6 & 7]. mailto:miqdam_tc@uotechnology.edu.iq miqdam tariq chaichan al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 3344 (2014) 34 diesel engine idling increases fuel consumption, engine wear, and required engine maintenance. the fuel consumption for diesel trucks at idle is typically 0.8–1.5 g/hr, depending on the engine size, ambient temperature, and load for hvac and other electrical loads. idling also causes undesirable emissions. the average emissions for heavy-duty diesel engines are shown in table 1. table 1, heavy duty diesel engine emissions at idle (g/hr) [8]. emission heavy duty diesel voltaic organic compounds (voc) 12.6 carbon monoxide (co) 94.6 oxides of nitrogen (nox) 144* particulate matters (pm) 2.57 carbon dioxide (co2) 8.224* source: environmental protection agency (epa) web site: www.epa.gov./oms/consumer/f98014.htm (april 1998) and *http://www.epa.gov/otaq/retrofit/decuments/r02025.p df (october 2002). heavy-duty trucks are typically parked and idled so the driver can rest at truck stops and roadside rest areas instead of checking into a motel. these stops can have hundreds of trucks idling in the parking area at once. diesel-powered trucks at idle produce noise, vibrations, and emissions that affect drivers, other truck stop or rest area patrons, and neighbors [9 & 10]. long duration idling consumes over one billion gallons of fuel annually in the united states, at a cost of over $2.5 billion [11]. idling of trucks, alone, is estimated to emit 11 million tons of co2, 180,000 tons of nitrogen oxides (nox), and 5,000 tons of fine pm each year. a single hour of truck engine idling consumes approximately one gallon of fuel and emits approximately 20 pounds of co2 [12]. warming up or cooling down a vehicle is the most common reason given for idling‚ in the winter and summer. a study of diesel school buses waiting in the wintertime found that restart and immediate departure produced fewer air pollutants compared to idling [13]. the usepa measured pm, nox, co, and pah from buses under idle and restart conditions and found that for periods longer than three minutes, more pollution was created by idling than by turning buses off and restarting them. in all cases they identify turning off the engine and restarting with immediate departure as a preferred approach [14]. the risks from elevated pollution due to idling extend to passengers as well as to people outside the vehicles. research shows that school buses self-pollute, meaning that emissions from the bus enter directly into the passenger compartment, even when the windows are closed. these pollutants concentrate more during idling [15 & 16]. opening the door of the bus after time spent idling, as is often done when buses are waiting to pick up children, can cause a spike in pm concentrations inside the bus [17]. the present investigations aims to measure the effect of idle time accompanied with using egr and variable injection timings on di multicylinders diesel engine emitted emissions at idle period. 2. experimental setup all experiments were performed with four cylinders di fiat engine. the engine was mounted on a test-bed and connected to a hydraulic dynamometer. power is supplied to the engine control unit, low pressure fuel pump and glow plug by a 12v automotive battery. in this study, the idle rpm was chosen at 1000 rpm to mimic the field observations. the 30-minute continuous idling period was chosen as a compromise emitted emissions. fig. 1 represents the rig used in recent study. table 2 illustrates the used engine specifications. the experimental study is foxed on investigating the effect of tested egr rates and different injection strategies on engine emitted emissions. fig. 2 shows the prodit heat exchanger used as egr unit. different combinations are assessed to study the effect of pilot injection strategy on idling period. two retarded injection timing (15 & 12 o btdc), and two advanced injection timing (20 & 23 o btdc) were used to study the effect of injection timing on engine idle at constant speed 1000 rpm. the results were compared with optimum injection timing (17 o btdc). the effect of variable engine idle speeds (600, 800, 1000 and 1100) were studied at constant it (17°btdc). http://www.epa.gov./oms/consumer/f98014.htm miqdam tariq chaichan al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 3344 (2014) 35 table 2, the tested engine specifications. fig. 1. photographic picture for the experimental rig. exhaust gas (smoke) opacity was measured continuously with the avl 439 partial flow opacimeter, which is particularly suitable for dynamic testing measurements with a response time less than 0.1 s and an accuracy of 0.1 per cent opacity. co with a non-dispersive infrared (ndir) analyzer and hcs with a flame-ionization detector (fid) were measured. nox was measured using a chemiluminescence analyzer. table 3 represents the equipment, detection principle and accuracy of measuring devices. all analyzers were calibrated at science and technology ministry of iraq. finally, combustion noise was measured with an avl 450 combustion noise meter. fig. 2. egr assembly used in the present study. 2.1. experimental procedure the experimental schedule included operating engine at different injection timing. four injection timings and three egr were studied. it must be highlighted that a preconditioning procedure was followed before most of the tests, in order to remove the deposited particulate matter on the exhaust pipe walls, which could be blown out and released during the following experimental trials. this procedure was followed before the idle operation and the fully warmed-up tests. 2.2. properties of tested fuel the conventional diesel fuel used was supplied by the al-doura refineries – baghdad, iraq and represents the typical, high sulfur (1% by weight) diesel fuel. the fuel properties are given in table 4. engine type 4cyl., 4-stroke engine model td 313 diesel engine rig combustion type di, water cooled, natural aspirated displacement 3.666 l valve per cylinder two bore 100 mm stroke 110 mm compression ratio 17:1 fuel injection pump unit pump 26 mm diameter plunger fuel injection nozzle hole nozzle: 10 nozzle holes nozzle hole dia.= (0.48mm) spray angle= 160 o nozzle opening pressure= 40 mpa miqdam tariq chaichan al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 3344 (2014) 36 table 3, summary of equipment, detection principle and accuracy of measurements. measuring item detection principle equipment (maker) scale range accuracy co ndir (non dispersive infrared) multigas mode 4880 0-10% vol. 0.01% co2 ndir (non dispersive infrared) multigas mode 4880 0-25% vol. 0.01% hc fid (flame ionization detector) multigas mode 4880 0-1000 ppm 0.01% nox cld (chemical luminescence detector) multigas mode 4880 0-1000 ppm 0.02% overall sound pressure precision sound level meter 4615 italy made 0-200 db 0.76% smoke opacity partial flow opacimeter avl 439 0-20 % vol. 0.24% table 4, diesel fuel used in recent study properties. 2.3. engine speed stability the idle stability depends strongly on the combustion process. misfires have a negative effect on the idle stability. during idle application from 600 to 1000 rpm engine speed stability was detected and ensured throughout the whole test. 3. results and discussions idle emissions from di multi cylinder fiat engine was considered in this study. the tests were conducted to measure the engine exhaust emissions to prepare acceptable data for what happening at idle period. many variables were tested as the following: 3.1. idling time effect fig.3 shows the effect of idling time on co2 concentrations when the engine runs at optimum injection timing (oit) and 1000 rpm. idling time=30 minute was chosen to clarify idle time effect, because this period occurrence is possible in traffics; like stopping in traffic light or in congestion, or as happens in iraq stopping in control points for frisking. co2 increase with increasing idling time to 10-15 min, after that it reduced with increasing time. increasing co2 concentrations means better combustion, while its reduction means poor combustion. co2 concentration reduced with increasing egr rates. fig. 3. idling time effect on co2 concentrations for variable egr rates at oit and 1000 rpm. egr addition will be on air account and will create poor and very rich zones. these zones increase co and hc concentrations on co2 account. the reduction in co2 concentration was 1.4, 3.58 and 7.1% for egr=10, 20 and 30 respectively compared with egr rate = 0%. 5.4 5.6 5.8 6 6.2 6.4 6.6 0 10 20 30 40 c o 2 c o n c e n tr a ti o n ( % v o l. ) idling time (min.) 17°btdc, 1000 rpm egr=0% egr=10% egr=20% egr=30% specification diesel chemical formula c10.8h18.7 mole weight (g) 148.3 density (g/cm 3 at 20 o c) 0.84 boiling point ( o c) 180-330 heat of evaporation (kj/kg) 280 lower heat value (mj/kg) 42.5 liquid viscosity (cp at 20 o c) 3.03 surface tension (mn/m at 20 o c) 34.1 flash point ( o c) 78 stoichiometric air fuel ratio 14.4 cetane number 45 auto-ignition ( o c) 235 carbon content (wt%) 87.4 oxygen content (wt%) 0 miqdam tariq chaichan al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 3344 (2014) 37 fig. 4. idling time effect on co concentrations for variable egr rates at oit and 1000 rpm. co emissions are generally low during idling and reduced further with advancing idle time from 0 to 15-20 min, after that it started to increase as fig. 4 represents. co reductions confirm the previous results that there is a combustion improvement during this period, due to engine heat improvements. fig. 5. idling time effect on hc concentrations for variable egr rates at oit and 1000 rpm. fig. 6. idling time effect on nox concentrations for variable egr rates at oit and 1000 rpm. co concentrations increased due to combustion deterioration, since continue heating will cause co2 to dissociate to co. adding egr increases co concentration for all rates districting its negative effect on this emission. the increments in co concentration with egr addition were 4.33, 27.67 & 53.57% for egr rates= 10, 20 & 30 respectively compared with adding 0% egr. since diesel engines generally have excess oxygen and high combustion temperatures, co emissions are generally much lower than co2 emissions. a significant amount of hc emissions are developed during the cold start of a diesel engine. a cold start is significantly below normal operating temperature. hc emissions occur mainly from poor fuel vaporization, which occurs during cold start. for the engine idle tests, data was acquired after the engine is wormed up, which never included any cold start emissions. increasing idle time increases hc concentrations as fig. 5 declines. also, increasing egr rates added to combustion chamber increased hc concentrations. the increments were 4.09, 11.06 & 17.21% for egr rates= 10, 20 & 30 respectively compared with adding 0% egr. idling time extension increased nox concentrations for egr=0% case, as fig. 6 reveals. but this extension reduced nox in the other studied cases. increasing idle time means increasing heat inside combustion chamber due to reduction in engine cooling abilities. increasing heat gives higher nox concentrations as a result. adding egr reduces combustion chamber temperature and the heat produced from combustion, this effect causes nox concentration to reduce. the effect of egr addition is to reduce nox and that is its duty. nox concentration reduced by about 9.11, 14.83 & 24.788% for egr rates= 10, 20 & 30% respectively compared with egr=0%. 0 0.02 0.04 0.06 0.08 0.1 0.12 0 10 20 30 40 m a x . c o c o n c e n tr a ti o n s (% v o l. ) idling time (min.) 17°btdc, 1000 rpm egr=0% egr=10% egr=20% egr=30% 60 70 80 90 100 110 120 0 10 20 30 40 h c c o n c e n tr a ti o n ( p p m ) idling time (min.) 17°btdc, 1000 rpm egr=0% egr=10% egr=20% egr=30% 40 50 60 70 80 90 0 10 20 30 40 n o x c o n c e n tr a ti o n ( p p m ) idling time (min.) 17°btdc, 1000 rpm egr=0% egr=10% egr=20% egr=30% miqdam tariq chaichan al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 3344 (2014) 38 fig. 7. idling time effect on smoke opacity for variable egr rates at oit and 1000 rpm. low combustion temperatures and nonstoichiometric oxygen conditions result in incompletely burned fuel, and various concentrations of particulates largely of carbon composition. engine emitted these fine particulates consisted of elemental carbon (ec), organic carbon (oc), metals from fuel and engines wear, and sulfates with bound water. egr effect on smoke opacity conflict with its effect on nox, as fig. 7 represents. increasing egr rates increased smoke opacity, as well as increasing idling time increased opacity. opacity reduction needs high temperatures to reduce smoke, while adding egr reduces these temperatures causing increment in opacity. increasing idling time increases heat slightly inside combustion chamber. but it also increases heterogeneous zones which causes many rich zones produces higher opacity. for 0% egr the increment in opacity because of increasing idling time was 10%. the increment in smoke opacity was 1.37, 4.26 & 8.27 for egr rates=10, 20 & 30% respectively compared to 0% egr. engine noise reduced slightly with increasing idle time from zero to 10 minutes, but it return to increase after that with engine idle continuing, as fig. 8 clarifies. adding egr reduces engine noise due to the relation between pressure rates inside combustion chamber and noise. egr addition reduces combustion efficiency and pressure rates as a result engine noise reduced. the reduction in engine noise was 2, 3.72 & 5.08% for egr rates =10, 20 & 30% compared to 0% egr. fig. 8. idling time effect on engine noise for variable egr rates at oit and 1000 rpm. 3.2. engine speed effect experiments were conducted on the engine to measure co, co2, nox, hc, opacity during idling conditions. period of 30 min. was used as idling time and injection timing was fixed at optimum injection timing. co2 emissions are a direct function of fuel consumption. during combustion, the products from the carbon in the fuel are co2, and the byproducts are co, hc, and formaldehydes. the majority of the carbon products are formed into co2, so as more fuel is consumed like by increasing engine idle speed, co2 concentrations increase, as fig. 9 reveals. fig. 9. engine speed effect on co2 concentrations for variable egr rates at oit for 30 min idling run. 6 6.5 7 7.5 8 8.5 9 0 10 20 30 40 m a x . o p a c it y ( % ) idling time (min.) 17°btdc, 1000 rpm egr=0% egr=10% egr=20% egr=30% 78 79 80 81 82 83 84 85 86 87 88 0 10 20 30 40 m a x . n o is e (d b ) idling time (min.) 17°btdc, 1000 rpm egr=0% egr=10% egr=20% egr=30% 5.7 5.8 5.9 6 6.1 6.2 6.3 6.4 6.5 500 700 900 1100 m a x . c o 2 c o n c e n tr a ti o n ( % v o l. ) engine speed (rpm) 17°btdc, 30 min. idling egr=0% egr=10% egr=20% egr=30% miqdam tariq chaichan al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 3344 (2014) 39 co2 concentrations increased about 9.15% with increasing idle speed from 600 to 1000 rpm. adding egr reduced these concentrations for the tested range. increasing engine speed increases air and heat inside combustion chamber resulting in better combustion. better combustion means higher co2 concentrations. fig. 10. engine speed effect on co concentrations for variable egr rates at oit for 30 min idling run. co concentrations behave in the opposite of co2, as fig. 10 manifests. increasing idle speed reduced co concentrations with about 23.63%. while increasing egr rates increased co concentration, for the same reason mentioned previously. the increments were 4.8, 10.9 & 16.18% for egr=10, 20 & 30% respectively compared to 0% egr. fig. 11 shows idle engine speed effect on hc concentrations for several egr rates. hc concentrations behave as co concentrations for same reasons. it reduced with increasing engine idle speed with about 24.28%. while it increased with increasing egr rates. increments were 3.24, 5.67 & 10.27% for egr=10, 20 & 30% respectively compared to 0% egr. fig. 11. engine speed effect on hc concentrations for variable egr rates at oit for 30 min idling run. egr duty is to reduce nox and that what fig. 12 demonstrates. nox concentrations reduced with increasing egr rates, and it reduced even more with increasing idle speed on the contrary of 0% egr case. in the normal case increasing idle speed means increasing air and heat inside combustion timing with available time for formation (where idle speeds can be considered low speeds). in this case, increasing egr rates improved its effect with time (it must be put in mind those measuring max. concentrations after the engine idling for half an hour). low speed idling made many rich zones in combustion chamber which produced local high temperatures even with egr addition due to reduction in turbulence inside combustion chamber. the reduction in concentrations were 3.63, 9.44 & 13.55% for egr rates= 10, 20 & 30% respectively compared with egr=0%. fig. 12. engine speed effect on nox concentrations for variable egr rates at oit for 30 min idling run. fig. 13. engine speed effect on smoke opacity for variable egr rates at oit for 30 min idling run. smoke opacity reduced with increasing idle speed, but it increased with egr addition, as fig. 13 demonstrates. increasing engine speed (from 0.06 0.07 0.08 0.09 0.1 0.11 0.12 0.13 0.14 500 700 900 1100 m a x . c o c o n c e n tr a ti o n ( % v o l. ) engine speed (rpm) 17°btdc, 30 min. idling egr=0% egr=10% egr=20% egr=30% 50 55 60 65 70 75 80 500 700 900 1100 m a x . h c c o n c e n tr a ti o n ( p p m ) engine speed (rpm) 17°btdc, 30 min. idling egr=0% egr=10% egr=20% egr=30% 50 55 60 65 70 75 500 700 900 1100 m a x . n o x c o n c e n tr a ti o n ( p p m ) engine speed (rpm) 17°btdc, 30 min. idling egr=0% egr=10% egr=20% egr=30% 7.4 7.6 7.8 8 8.2 8.4 8.6 8.8 500 700 900 1100 m a x . o p a c it y ( % ) engine speed (rpm) 17°btdc, 30 min. idling egr=0% egr=10% egr=20% egr=30% miqdam tariq chaichan al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 3344 (2014) 40 very low speed as 600 rpm to moderate speed as 1100 rpm) increases combustion efficiency and reduces opacity. egr effect resists this effect, but the available results indicate that increasing combustion efficiency overcomes egr effect. opacity increments were 1.16, 2.23 & 4.64% for egr rates=10, 20 & 30% respectively compared to 0% egr. engine noise increased with adding egr at low speeds and reduced for higher speeds compared with no egr addition, as fig. 14 represents. at low idle speeds engine vibration increased highly causing high noise rate, while at higher idle speeds large reduction in engine vibration achieved causing lower noise. adding egr in good combustion conditions results in reduction in engine noise, arising from reduction in pressure combustion rates accompanied with this addition. fig. 14. engine speed effect on engine noise for variable egr rates at oit for 30 min idling run. 3.3. injection timing effect co2 concentrations reduced with retarding injection timing from oit highly, and it reduced slightly with advancing it also, as fig. 15 reveals. retarding it causes late combustion which means part of it will be in the expansion stroke; result in less power and lower exhaust temperatures. these factors causes bad combustion which produces low co2 concentration, associated with higher co and hc concentrations (figs. 16 & 17) at these it. advancing it increases pressure rates and heat produced inside combustion chamber resulting in better combustion. this combustion improvement doesn’t affect co2 while it reduces co and hc concentration highly as figs 15, 16 & 17 represent. retarding injection timing was considered one of the treatments can be used to reduce nox concentrations. egr addition with retarding it together caused lower nox concentration, as fig. 18 reveals. contrary to opacity which increased highly with these two factors accompanied as fig. 19 represents. the conditions reversed at advancing it, where heat and available time increased generating more nox concentrations. in this region two conflicting factors applied and egr addition still reducing nox (fig. 18) and increases opacity (fig. 19). fig. 15. injection timing effect on co2 concentrations for variable egr rates at oit for 30 min idling run. fig. 16. injection timing effect on co concentrations for variable egr rates at oit for 30 min idling run. engine noise increased highly with egr addition and it retarding, as fig. 20 shows. retarding engine it increased engine vibration, while adding egr made combustion more difficult, and the result higher engine noise. in contrast to the former mentioned, adding egr with advanced it reduced noise. advancing it increases produced pressure rates from combustion witch increases noise, while adding egr reduces noise. the resultant from applying these two factors clarifies that egr effect is dominant, as the figure insures. 80 82 84 86 88 90 92 94 96 98 500 700 900 1100 m a x . n o is e (d b ) engine speed (rpm) 17°btdc, 30 min. idling egr=0% egr=10% egr=20% egr=30% 5 5.5 6 6.5 7 10 15 20 25 m a x . c o 2 c o n c e n tr a ti o n s (% v o l. ) injection timing (°btdc) 1000 rpm, 30 min. idling egr=0% egr=10% egr=20% egr=30% 0.06 0.07 0.08 0.09 0.1 0.11 0.12 0.13 0.14 10 15 20 25 m a x . c o c o n c e n tr a ti o n s (% v o l. ) injection timing (°btdc) 1000 rpm, 30 min. idling egr=0% egr=10% egr=20% miqdam tariq chaichan al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 3344 (2014) 41 fig. 17. injection timing effect on hc concentrations for variable egr rates at oit for 30 min idling run. fig. 18. injection timing effect on nox concentrations for variable egr rates at oit for 30 min idling run. fig. 19. injection timing effect on smoke opacity for variable egr rates at oit for 30 min idling run. fig. 20. injection timing effect on engine noise for variable egr rates at oit for 30 min idling run. 3.4. comparison with other studies it is difficult to compare results of recent study with other similar ones, due to variable tests procedures and measurements. in fig. 21 a comparison of nox concentrations for three similar studies at engine speed 600 rpm and variable injection timing for each study. egr=20% results for recent study was chosen for this comparison depending on several studies like references 18 and 19 which confirm that using 20% egr gives the best results in reducing nox with limited effect on brake specific fuel consumption and thermal efficiency. brodrick [20] showed that nox concentrations reached its minimum values for idle period of 10-15 minutes after that it increased highly. hearne [21] results are similar to recent study except for the values at 5 min. which is high due to the measuring procedure for school bus and no egr employing. khan [22] studied several cars models and its effects on emissions at idle period. the study focused on models from 1965 to 2005. the average as it seemed in the figure high compared with recent study because egr was not used in the tested engine. finally, all results indicate high and hazard nox concentrations at idle time. 4. conclusions although the small data set reported here improves our knowledge of engine idle emissions, a number of important questions remain unanswered. data from many more engines from a broader range of manufacturers and using years and maintenance quality are necessary for accurate emissions factors that can be used in air quality modeling. this study insures the need for 50 55 60 65 70 75 80 10 15 20 25 m a x . h c c o n c e n tr a ti o n s (p p m ) injection timing (°btdc) 1000 rpm, 30 min. idling egr=0% egr=10% egr=20% egr=30% 50 55 60 65 70 75 80 10 15 20 25 m a x . n o x c o n c e n tr a ti o n s (p p m ) injection timing (°btdc) 1000 rpm, 30 min. idling egr=0% egr=10% egr=20% egr=30% 7.2 7.4 7.6 7.8 8 8.2 8.4 8.6 8.8 9 10 15 20 25 m a x . o p a c it y ( % ) injection timing (°btdc) 1000 rpm, 30 min. idling egr=0% egr=10% egr=20% egr=30% 80 82 84 86 88 90 92 94 96 98 100 10 15 20 25 m a x . n o is e (d b ) injection timing (°btdc) 1000 rpm, 30 min. idling egr=0% egr=10% egr=20% egr=30% miqdam tariq chaichan al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 3344 (2014) 42 quick action from iraqi government and civil society enterprises to educate iraqi drivers about long idling time risks from economic and health point of view. idle emissions of co, hc, nox, smoke, noise and co2 at idle have been presented in this paper. three variables were used to test engine emissions when idling with egr addition in several rates. the tested variables were idling time, engine speed variation and injection timing variation. the results indicate that: fig. 21. comparison of recent study with other similar studies.  co2 concentrations increased with increasing idle time and engine speed, but it didn’t show clear effect for it advancing. in contrast, retarding it reduced these concentrations. operating the engine with egr addition caused a reduction for co2 concentration through idle time, increasing engine speed and with it variation.  co concentrations reduced in the first 10 min. of the engine idling period, and then it increased if this period continued. co reduced with increasing engine speed and advancing it. adding egr increased co for all the studied tests.  hc concentration increased with idle time advance, but it reduced with increasing idle speed and advancing engine it. adding egr increased hc for all the studied tests.  nox concentrations reduced with adding egr for all the tested variables. nox concentrations increased with increasing idle time, engine speed and advancing it.  smoke opacity increased with increasing idle time and retarding it. while it reduced with increasing engine speed and advancing it. using egr increased opacity for all tested cases.  egr addition reduced engine noise for all tested cases. engine noise increased with increasing idle time and retarding it. noise reduced with increasing idle speed and advancing it. notation btdc before top dead centre co carbon monoxide co2 carbon dioxide db decibel egr exhaust gas recirculation hc unburnt hydrocarbon it injection timing nox nitrogen oxides pm particulate matters so smoke opacity 5. references [1] last b, houben h, rottner m, stotz i, influence of modern diesel cold start systems on the cold start, warm-up and emissions of diesel engines, beru ag, germany, 2008. [2] national academy of sciences (nas), technologies and approaches to reducing the fuel consumption of medium and heavy-duty vehicles, washington d.c., the national academies press, 2010. [3] lutsey n; brodrick c j; sperling d and oglesby c, heavy-duty truck idling characteristics: results from a nationwide survey. transportation research record no. 1880, trb, national research council, washington, d.c., pp: 29–38, 2004. [4] gaines l; vyas a d and anderson j l, estimation of fuel use by idling commercial trucks, transportation research board annual meeting 2006 paper #06-2567, 2006. [5] denning c and kustin c, the good haul: innovations that improve freight transportation and improve the environment, environmental defense fund, new york, ny 2010. [6] ham c, diesel fuel emissions and truck idling: the oregon interstate 5 idle-free corridor project a bounded rationality perspective, m sc thesis, political science, cascades campus, 2008. [7] carrico amanda c r, paul padgett p, michael p, vandenbergh jonathan gilligan v j and kenneth a. wallston k a, costly 40 60 80 100 120 140 160 5 10 15 20 25 30 n o x c o n c e n tr a ti o n s (p p m ) time (min.) 10°btdc, 600 rpm brodrick, 2002 hearne, 2003 khan, 2006 recent study miqdam tariq chaichan al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 3344 (2014) 43 myths: an analysis of idling beliefs and behavior in personal motor vehicles, energy policy, vol. 37, no. 8, pp: 2881-2888, august, 2009. [8] proc k, nitschke b, wagner f, anderson m, slezak l, idle reduction technology demonstration plan, national renewable energy laboratory, report no. nrel/tp540-34872, 2003. [9] stephanie g and mee c, toronto public health, improving toronto’s idling control bylaw, technical report, toronto, ontario, 2009. [10] khan a s, clark n , thompson g j, wayne w s, gautam m, lyons d w and hawelti d, idle emissions from heavy-duty diesel vehicles: review and recent data, j. air & waste manage. assoc, vol. 56, pp: 1404– 141, 2006. [11] usepa “united state environment protection agency”: smart way transport, 2009. available at: http://www.epa.gov/smartway/transport/inde x.htm. [12] united states environmental protection agency office of solid waste and emergency response, green remediation best management practices: clean fuel & emission technologies for site cleanup, (5102g) epa 542-f-10-008, august 2010 [13] kinsey j s, williams d c, dong y and logan r, clean school bus study, united states environmental protection agency (usepa). 2007. available at: http://www.epa.gov/region2/cleanschoolbus/s tudy.html. [14] downing k and matthews s, improving truck efficiency and reducing idling, submitted to: house interim committee on environment and water, october, 2010. [15] environmental defense, the clean air task force and the conroe independent school district, measuring pollution levels inside texas school buses, 2007. available at: http://www.edf.org/documents/6153_bus_fin dings.pdf. [16] diane b, berry p, bouchet v, charron d and clarke k l, human health in a changing climate: a canadian assessment of vulnerabilities and adaptive capacity, health canada. 2008. available at: http://www.hc-sc.gc.ca/ewhemt/climat/eval/index-eng.php#guide. [17] energy information administration, annual energy outlook 2010, doe/eia-0383 (2010), washington, d.c., may, 2010. available at: http://www.eia.doe.gov/oiaf/aeo/ [18] chaichan m t & saleh a m, practical investigation of the effect of egr on di multi cylinders diesel engine emissions, anbar journal for engineering science (ajes), vol. 6, no. 3, pp: 401-410, 2013. [19] ghazikhani m, feyz v & joharchi a, “experimental investigation of the exhaust gas recirculation effects on irreversibility and brake specific fuel consumption of indirect injection diesel engines”, applied thermal engineering, vol. 30, pp: 1711-1718, 2010. [20] brodrick c j, dwyer h a, farshchi m, harris d b and king g k, effects of engine speed and accessory load on idling emissions from heavy-duty diesel truck engines, air & waste manage. assoc., vol.52, pp: 10261031, 2002. [21] hearne j s, school bus idling and mobile diesel emissions testing: effect of fuel type and development of a mobile test cycle, msc thesis, the faculty of rowan university, 2003. [22] khan a b m s, clark n n, thompson g j, wayne w s, gautam m, lyons d w and hawelti d, idle emissions from heavy-duty diesel vehicles: review and recent data, j. air & waste manage. assoc., vol. 56, pp: 14041419, 2006 (2014)3344 ، صفحت4، العذد10دجلت الخىارزمي الهنذسيت المجلمقذام طارق جيجان م وحىقيج الحقه على الملىثاث المنبعثت خالل (egr)حأثير حذوير الغاز العادم دراست عمليت ل فخرة الحياد مقذام طارق جيجان ةاىجاٍعت اىخنْىىىجً /قسٌ هْذست اىَنائِ واىَعذاث miqdam_tc@uotechnology.edu.iq: اىبشٌذ األىنخشوًّ الخالصت حقذً هزة اىذساست . حقٍٍذ هزة اىفخشة بقىاٍِّ ٍيضٍتاىى اَُ ىٌ ٌخٌ ، واىحٍاد ٍذةخاله اىذٌضه ىيخذٍت اىثقٍيت اىىقىد وحقيو ٍِ ّىعٍت اىجىحسخهيل سٍاساث (co)ُ سبىامسٍذ اىلوإر دسسج ٍيىثاث اىحٍاد ألوه ا. ٍعيىٍاث شاٍيت ٍشحبطت بْخائج عَيٍت حَج عيى ٍحشك دٌضه ري حقِ ٍباشش ٍخعذد األسطىاّاث ، عْذ اضافت ثالد ّسب واىضىضاء (co2)سبىُ امسٍذ اىلووعخىٍت اىذخاُ وثاًّ ا( nox)وأماسٍذ اىٍْخشوجٍِ ( hc)واىهٍذسوماسبىّاث غٍش اىَحخشقت .ٍخخيفت ٍِ اىغاص اىعادً اىَذوس اىى ٍشعب اىذخىه ىنو األخخباساث coوحضداد حشامٍض . ىخقذٌٌ حىقٍج اىحقِ اواضح احأثٍشوسشعت اىحٍاد ىيَحشك، ىنْها ىٌ حظهش بضٌادة صٍِ اىحٍاد co2حضداد حشامٍض noxحقو حشامٍض . بخقذً حىقٍج اىحٍاد، وىنْها قيج بضٌادة سشعت اىحٍاد وحقذٌٌ حىقٍج اىحقِ hc، مَا صادث حشامٍض (egr)باضافت غاص عادً ٍذوس وحضداد عخىٍت . اىخشامٍض بضٌادة صٍِ اىحٍاد وسشعت اىَحشك وحقذٌٌ حىقٍج اىحقِ ٓوىنو اىَخغٍشاث اىَذسوست، وحضداد هز egrباضافت غاص عادً ٍذوس ضىضاء اىَحشك ىنو egrحقيو اضافت . صادث عخىٍت اىذخاُ ىنو اىحاالث اىَذسوست egrاىذخاُ بضٌادة صٍِ اىحٍاد وحأخٍش حىقٍج اىحقِ، وباسخخذاً .وحأخٍش حىقٍج اىحقِ اىحاالث اىَخخبشة، وحضداد اىضىضاء بضٌادة صٍِ اىحٍاد mailto:miqdam_tc@uotechnology.edu.iq 99-109 al-khw arizmi engineering journal,vol. the effect of magnetic field abdulhassan a. karamallah *,**,*** department (received abstract this work presents an experimental study of heat transfer and flow of fe3o4-distilled water at concentrations of field. all the tests are carried out with reynolds number range (2900 w/m2). the results show that, the nanofluid concentration and magnetic intensity increase, the nusselt number increases. the maximum enhancement in nusselt number with magnetic nanofluid is (5.4 %, 26.4 %, 42.7 %) for volume concentration (0.3, 0.6, 0.9 %) re 0.3 tesla) respectively to (43.9, 44.3, 46 %) with volume concentration (0.9 %). the decreases with the increasing of reynold number concentration increase and the intensity of magnet and decreases with increase of reynold number. keyword: magnetic effect on nanofluid, 1. introduction conventional fluids, such as water, lubricant, and ethylene glycol are normally used as heat transfer fluids. solid particles as an additive suspended into the base fluid to enhancement transfer by change the properties of fluid sundar et al. [2] studied experimentally the convective heat transfer coefficient and friction factor characteristics of fe3o4 nano water that, for flowed in a circular tube. the heat transfer coefficient was enhanced by 30.96 % and friction factor by 10.01 % at 0.6 % nano fe volume concentration compared to at similar operating conditions. jie et al. [3] studied experimentally the forced convective heat transfer properties of water with fe3 ghofrani et al. [4] experimentally invest forced convection heat transfer of ferro passing through a circular copper tube in the arizmi engineering journal,vol. 12, no. 3, p.p. 99109 (2016) the effect of magnetic field with nanofluid on heat transfer in a horizontal pipe abdulhassan a. karamallah* laith jaafer habeeb ali habeeb asker*** *,**,*** department of mechanical engineering / university of technology *email: dr_abdulhassank@yahoo.com ** email: laithjaafer@yahoo.com *** email: ali_habeeb88@yahoo.com (received 15 december 2015; accepted 19 april 2016) an experimental study of heat transfer and flow of distilled water and distilled water at concentrations of (φ = 0.3, 0.6, 0.9 %) by volume in a horizontal pipe with constant magnetic all the tests are carried out with reynolds number range (2900-9820) and uniform heat flux (11262 the nanofluid concentration and magnetic intensity increase, the nusselt number increases. the maximum enhancement in nusselt number with magnetic nanofluid is (5.4 %, 26.4 %, 42.7 %) for volume concentration (0.3, 0.6, 0.9 %) respectively. the enhancement is maximized with magnetic intensity (0.1, 0.2, 0.3 tesla) respectively to (43.9, 44.3, 46 %) with volume concentration (0.9 %). the heat transfer reynold number with using magnets. the friction factor increases with concentration increase and the intensity of magnet and decreases with increase of reynold number. magnetic effect on nanofluid, heat transfer enhancement by nanofluid, turbulent flow in horizontal pip conventional fluids, such as water, lubricant, and ethylene glycol are normally used as heat transfer fluids. solid particles as an additive enhancement heat transfer by change the properties of fluid. [1]. studied experimentally the ficient and friction anofluid added to flowed in a circular tube. the heat ficient was enhanced by 30.96 % and at 0.6 % nano fe3o4 volume concentration compared to flow of water jie et al. [3] studied experimentally the forced convective heat 3o4 nanofluid. ly investigated on forced convection heat transfer of ferrofluid flow passing through a circular copper tube in the presence of an alternating magnetic maximum enhancement convection heat transfer was observed [5] studied numerically the turbulent (fe water) flow in a square straight channel. reynolds number range was from 10,000 to 50,000 and nanoparticle volume concentration was from 0 % to 2 %. mohammad et al. [6] numerically the forced convective heat transfer of water based fe3o4 nanofluid (ferrofluid) in the presence of an alternating non field. comparing the results with zero magnetic field case, the result showed that the heat transfe enhanced increases when the reynolds number increased and reached a maximum of 13.9 % at re=2000 and the maximum pressure drop increase of 6 % at re=2000. investigated experimentally and numerically the effect of a magnetic field on t forced convection of fe3o al-khwarizmi engineering journal (2016) nanofluid on heat transfer laith jaafer habeeb** university of technology and metal oxide nanofluid by volume in a horizontal pipe with constant magnetic 9820) and uniform heat flux (11262-19562 the nanofluid concentration and magnetic intensity increase, the nusselt number increases. the maximum enhancement in nusselt number with magnetic nanofluid is (5.4 %, 26.4 %, 42.7 %) for with magnetic intensity (0.1, 0.2, heat transfer enhancement he friction factor increases with nano volume concentration increase and the intensity of magnet and decreases with increase of reynold number. turbulent flow in horizontal pipe. of an alternating magnetic field, a maximum enhancement was 27.6% in the transfer was observed. nor et al. lly the turbulent (fe3o4water) flow in a square straight channel. reynolds number range was from 10,000 to 50,000 and nanoparticle volume concentration was from 0 % mohammad et al. [6] investigated numerically the forced convective heat transfer of fluid (ferrofluid) in the presence of an alternating non-uniform magnetic field. comparing the results with zero magnetic field case, the result showed that the heat transfer enhanced increases when the reynolds number increased and reached a maximum of 13.9 % at re=2000 and the maximum pressure drop increase of 6 % at re=2000. mohammad et al. [7] investigated experimentally and numerically the magnetic field on the fully developed o4 flow inside a copper abdulhassan a. karamallah al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 99109 (2016) 100 tube. the results show that the heat transfer increases with increase of alternating magnetic field frequency. mehdi [8] evaluated theoretically the flow and heat transfer characteristics of the suspensions containing fe3o4 magnetic nanoparticles in turbulent flow regime. nusselt number was increased by raising the reynolds number and mean concentration. 2. nanofluid preparation and properties the nanoparticles and the distilled water are mixed directly by mixer with (2400 rpm) for 20 minutes before each experiment, the concentrations used in the experiments are (φ = 0, 0.3, 0.6 and 0.9 % by volume). volume of water used in the test rig is (5 l). the volume concentration is evaluated from the following relation in percentage: � = ������ � ���� ������� ������ � ���� ������� + ������ � ����� × 100 … (1) � = (� �� )������ !"#�$ (� �� )������ !"#�$ + (� �� )%�!& × 100 …(2) the properties of nanofluid (viscosity, specific heat and density) are measured experimentally and listed in table (1) below table 1, experimental measurements for the properties of nanofluid . distilled water fe3o4 (80 nm) – distilled water nanoparticles concentration (vol. %) 0.0 0.3 0.6 0.9 viscosity (n.s/m2) 5.96*10-4 7.73*10-4 8.345*10-4 8.8869*10-4 specific heat (kj/kg.k) 4.1821 4.156 4.0864 4.0255 density (kg/m3) 990.1 1001.4 1001.8 1020.7 thermal conductivity (w/m.k) 0.637 0.6426 0.6482 0.6539 for specific heat measurements: the energy balance for water case: qh=qv+qw …(3) energy balance in case of nanofluid takes the following form: qh= qnf + qv … (4) v i t = ��+ ,�+ ∆. + �/ ,/ ∆. … (5) the thermal conductivity was estimated from the equation [9] 12 = 1+ 34567854∅(678:;) 45678:∅(678:;) < … (6) where: 1�+ = 1�1+ … (7) 3. experimental set up and procedure the experimental rig consists of copper tube of inner and outer diameter (14, 15.8) mm with 1500 mm length, a helical heat exchanger nanofluid tank, pumps, flow meters, thermorecorder, varic, electric board, magnets and fittings, as shown in figure (1). fig.1. schematic diagram of the experimental test rig. abdulhassan a. karamallah al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 99109 (2016) 101 the tube outer surface is electrically heated by a coil made from nichrome material to generate constant heat flux (2000 w). an electric insulator of fiberglass is winded over the tube. drilled ceramic bead elements are inserted around the wire heater to insulate the electrical heater and then the wire heater is winded around the pipe. an aluminum foil and sectional pipe insulation glass wool type was used to insulate the test section. eight thermocouples (k–type) were used to record the temperatures of variable locations of the test rig. six thermocouples were used to measure the temperatures along the outer surface of test section. the thermocouples were located along the test section with a space distance of (22 cm) between each one. two thermocouples were immersed in the flow stream to measure the inlet and outlet temperatures of the fluid in the test section. a stainless steel tank of (24 l) capacity was used to accumulate cold nanofluid from heat exchanger to feed the pump with the required amount of working fluid. spiral heat exchanger was fabricated from a copper tube coil of (15 m) long and (12.5 cm) diameter used to cool the hot nanofluid came from the test section. the coil is placed in a stainless steel tank of (125 l) capacity filled with re-circulating water. u-tube manometer was used to record the pressure drop across the test section. three types of magnets were used in this experimental work as presented in table (2), where the strength at surface and center of pipe were measured by gauss meter in ministry of science and technology. table 2, strength of the three magnets. no. type of magnet number of magnet used strength of magnet at surface (gauss) strength at center of pipe (20 mm) (gauss) 1 ferrite 5 1000 600 2 neodymium 20 2000 1200 3 neodymium 10 3000 2220 the experiments were done (1) with distilled water (2) with nanofluid: (fe3o4distilled water) at concentrations (φ = 0. 3, 0.6 and 0.9 % by volume) (3) with magnetic field at each concentration used three intensities (0.1, 0.2 and 0.3 tesla). all these tests were carried out under entrance region turbulent flow with reynolds number range (2950-9820), flow rate (1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5 l/min) and uniform heat flux range (11114-19643 w/m2). 4. data reduction the power on the tube outer surface is given by: ? = @ × a … (8) the amount of the heat transferred from the heating wire to the nanofluid is given by: c�+ = �d × ,�+ × (.� − .") … (9) the heat balance between the nanofluid (qnf) and heat input (p) is found to be within 10 % for all runs, that is: f = ? − c�+? < 10 % … (10) the heat flux is given by: id = c�+jk = c�+lmn … (11) the local heat transfer coefficient is calculated as follows: [11] 1. starting from the known values {id , tso(x)} 2. using the conduction equation in the cylinder to calculate tsi(x): id = c�+jk = 2l1∆o[.k�(o) − .k"(o)] lm∆o × ln (���") = 21[.k�(o) − .k"(o)] m × ln (���") … (12) 3. the mean bulk fluid temperature, tm(x) at the section (x): ti = i" to = �d ,�+ t.2 … (13) where = lm" is the perimeters; t.2 = i"lm"�d ,�+ to … (14) the variation of tm with respect to x is determined by integrating equation (13) from x = 0 to x and after simplifying using q′′ term and tm(x=0) =ti, or .2(o) = ." + (.� − .")� o … (15) thus, the local heat transfer coefficient becomes: ℎ(o) = id .k"(o) − .2(o) … (16) the local nusselt number is given by [2]: y�(o) = z[\ ]^8 … (17) abdulhassan a. karamallah al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 99109 (2016) 102 the average value of nusselt number in the thermal developing region can be expressed by: y� = ; _ ` y� (o)_ a to … (18) the experimental values of nusselt number are compared with the values estimated from: empirical correlation of gnielinski’s [2]. y� = b8cd(e&:;aaa)f ;5;4.hb8cd i.jkf lc:;m … (19) where; = (1.58��o� − 3.82):4 �� 2300 < o� <5 × 10pand 0.5 < ?� < 2000 based on the practically measured pressure drop, friction factor can be calculated using darcy equation, [12]: = 4×∆�×\ _×q×rc … (20) where: ∆? = s�+ tquuvwq^8 − 1x × y … (21) h: head of manometer. experimental procedure the first set of experiments is done with distilled water, in order to validate the rig performance. the second set of experiments include the study of nanofluid: iron oxide (fe3o4distilled water) with concentrations (φ = 0. 3, 0.6 and 0.9 % by volume). the third set of experiments included the magnetic field with each concentration for three intensity (0.1, 0.2 and 0.3 tesla). 1. preparation of nanofluid and put it in nanofluid tank. 2. switch the pump to circulate the nanofluid in the test rig. 3. the flow rate is adjusted by means of the control valve and the balance valve to get the desired flow rate. 4. switch on the electrical heater and adjusted to the desired heat flux by the regulating device. 5. the thermocouple readings are observed at the inlet and outlet of the test section until a steady state is obtained which is reached after (30-40) minutes. 6. after the steady state is reached, the following readings are recorded: temperature, flow rate, power, and pressure drop. the procedure is repeated for the other concentrations of the nanoparticle. the magnets is fixed on the pipe and repeat all the steps above for each type of magnets. 5. results and discussion figures (2) show comparison of present experimental work with results gnielinski’s equation and blasius equation ( = 0.316o�:a.4z), for distilled water to validate the rig performance. the variation of the nusselt number with reynolds number with different magnetic field intensity and ferrofluid concentration along the tube is shown in figures (3). the average nusselt number was increased with increasing ferrofluid volume concentration and with increasing magnetic intensity for each concentration, and it was increased with increasing reynolds number, because, the effective thermal conductivity of nanofluid increases with increasing volume fraction of the nanoparticles, which is explained by brownian motion of the nanoparticles, molecular level layering of the liquid at liquid/particle interface (wetability). enhanced thermal conductivity reduces resistance to thermal diffusion in the laminar sublayer of the boundary layer. figures (4) the effect of reynolds number on average nusselt number with different magnets and (5) represent the effect of reynolds number on average nusselt number with different volume concentration. the enhancement in nusselt number of the magnetic nanofluid with respect to the water reach the maximum value by (5.4 %, 26.4 %, 42.7 %) for ferrofluid volume concentration (0.3, 0.6, 0.9 %) respectively. also, for magnetic intensity (0.1, 0.2, and 0.3 tesla) with volume concentration (0.9 %), the enhancements were (43.9, 44.3, and 46 %) respectively. the enhancement with magnetic field is due to the viscous sublayer become very small (at the entrance region), the accumulation of the particle on the surface, and increasing in fraction, all these reason resulted the enhancement in heat transfer. figure (6) represents the effect of volume concentration on nusselt number with different flow rate of the ferrofluid the change of properties of fluid by adding nanoparticle cause enhancement in thermal properties and increase nusselt number with increased volume concentration. the comparison of the present experimental results with the published work, of sundar [2], is shown in figure, (7) nusselt number versus reynolds number and (8) for friction factor versus reynolds number. the pressure drop, increases with increased reynolds number, ferrofluid concentration and the magnetic field intensity. figures (9) shows the variation of friction factor with reynolds number. the friction factor increased with increasing the volume abdulhassan a. karamallah al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 99109 (2016) 103 concentration because increased in density of fluid resulted increased in pressure drop and the effect of intensity of magnet because drawn the fluid to a surface of pipe and increased fraction. decreasing fraction with increased reynold number. figures (10) show the effect of reynolds number on friction factor with different magnets. and (11) show the effect of reynolds number on friction factor with different volume concentration. the correlations between nusselt number and reynolds number are made by using power method for the working fluid with and without magnetic field with reynold number range (2950-9820). y� = ,o�2 … (22) (a) (b) fig. 2. (a) the effect of reynolds number on nusselt number for distilled water with gnielinski’s equation, (b) the effect of reynolds number on friction for distilled water with blasius equation. fig. 3. the effect of reynolds number on average nusselt number. abdulhassan a. karamallah al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 99109 (2016) 104 (a) (a) (b) (b) (c) (c) fig. 4. the effect of reynolds number on average nusselt number with different magnets. fig. 5. the effect of reynolds number on average nusselt number with different volume concentration. abdulhassan a. karamallah al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 99109 (2016) 105 fig. 6. the effect of volume concentration on nusselt number. fig. 7. comparison of experimental data of the present work with the l.syam sundar, the effect of reynold on nusselt number. fig. 8. comparison of experimental data of the present work with the l.syam sundar, the effect of reynold on friction factor. fig. 9. the effect of reynolds number on friction factor. abdulhassan a. karamallah al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 99109 (2016) 106 (a) (a) (b) (b) (c) (c) fig. 10. the effect of reynolds number on friction factor with different magnets. fig. 11. the effect of reynolds number on friction factor with different volume concentration. abdulhassan a. karamallah al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 99109 (2016) 107 6. conclusions the following points can be concluded from the present work: 1. the magnetic nanofluid fe3o4 (80 nm) – distilled water shows more heat transfer enhancement and higher nusselt number. the nanoparticles give higher heat transfer characteristics than the base fluid (distilled water). the maximum enhancement is (46%) acheived for magnetic nanofluid with concentration 0.9 % and magnetic field 0.3 tesla and the minimum enhancement is (3.2 %) established for magnetic nanofluid with concentration 0.3 % without magnetic field. 2. the heat transfer enhanced with increasing nanoparticles concentration. 3. the use of magnetic field increases the heat transfer enhancement, because the magnetic field gives higher nusselt number compared to water-distilled and magnetic nanofluid. the heat transfer enhanced with increasing magnetic intensity. 4. experimental measurements of the darcy friction factor of magnetic nanofluid give good agreement with the theoretical results of the friction factor from the correlation =0.316o�:a.4z for water the maximum deviation is (9.75%). 5.the ferrofluid will not cause a penalty drop in pressure but a little increase in pressure drop, for distilled water is (75-548 pa) and (104-635 pa) for nanofluid with constration (0.9%) and magnetic intensity (0.3tesla). with reynold number rang (2950-9820) and there is no need for additional pump power. nomenclature as cross-sectional area (m2) b magnetic field (tesla) c specific heat (j/kg.k) d diameter (m) f friction factor h heat transfer coefficient(w/m2.k) i current (a) k thermal conductivity (w/m.k) � length of the test section (m) �d mass flow rate (kg/s) nu nusselt number (-) pr prandtl number (-) q heat transfer rate (w) q heat flux (w/m2) r radius of pipe (m) re reynolds number (-) t temperature (k) t time (sec) u velocity (m/s) v voltage (volts) γ specific weight ∆p pressure drop across the tube ρ mass density (kg/m3) ϕ volume fraction of nanofluid subscripts ccl4 carbon tetrachloride f fluid h heat (i,o,s) in , out ,surface m mean nf nanofluid p particle pf particle fluid v vessel (aluminum vessel) w water x distance 7. references [1] veeranna sridhara and lakshmi narayan satapathy. “al2o3-based nanofluids: a review” nanoscale research letters, 6 (1), 456 a springer open journal, (2011). [2] l. syam sundar, m.t. naik, k.v. sharma, m.k. singh andt.ch. siva reddy. “experimental investigation of forced convection heat transfer and friction factor in a tube with fe3o4 magnetic nanofluid” elsevier inc. experimental thermal and fluid science 37 (2012) 65–71. [3] jie ma, yinchen xu, wenlie li, jiantao zhao, shuping zhang, and sergey basov. “experimental investigation into the forced convective heat transfer of aqueous fe3o4 nanofluids under transition region” hindawi publishing corporation. journal of nanoparticles volume 2013, article id 601363, 1-5. [4] a. ghofrani, m.h. dibaei, a. hakim sima , m.b. shafii “experimental investigation on laminar forced convection heat transfer of ferrofluids under an alternating magnetic field” experimental thermal and fluid science 49 (2013) 193–200. [5] azwadi, n. o. r., sidik, c., and jafni, h. (n.d.). “numerical simulation of forced heat convection turbulent magnetic nanofluid flow in a square channel” faculty of mechanical engineering, universiti teknologi malaysia, 81310 skudai, (2015). [6] mohammad goharkhah and mehdi ashjaee. “effect of an alternating nonuniform magnetic abdulhassan a. karamallah al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 99109 (2016) 108 field on ferrofluid flow and heat transfer in a channel” elsevier inc. journal of magnetism and magnetic materials, 362, 80–89, 2014. [7] mohammad hossein dibaee bonab, mohammad behshad shafii and mohammad hasan nobakhti. “experimental and numerical investigation of fully developed forced convection of water-based fe3o4 nanofluid passing through a tube in the presence of an alternating magnetic field” department of mechanical and aerospace engineering, islamic azad university, science and research branch, tehran, iran, 2015. [8] mehdi bahiraei. “effect of particle migration on flow and heat transfer characteristics of magnetic nanoparticle suspensions” elsevier inc. journal of molecular liquids, 209, 531– 538, 2015. [9] hossein dibaeebonab mohammed et, al.” numerical simulation of internal convection heat transfer of ferrofluid under alternating magnetic field” indian j.sci.res.1 (2):733-743, (2014). [10] kimmco rigid pipe covering www.kimmcoinsulation.com. [11] holman j. p., “heat transfer", 10th edition, by the mcgraw-hill companies, inc., 2010. [12] frank m. white, “fluid mechanics", fourth edition, macgraw-hill books, 2001. ��� ��م هللا �� � ا ������� ا���� ��د����12 ا ��ارز�� ا )2016( 99109، ��� 3، ا 109 !�� �"# ا2&/%ل ا ��ارة �0 ا��2ب ا0/�.-, � ا ��%ل ا �"�%ط �� �( ا ��ا)' �&�%ھ � ا *��� ا �� ��� ��م هللا 4 ����7 6 ج ** ��� 6 �7 �8��*** �� ا������ ا���������� * ,** ،***� / ��� �"#��"ا�!� �� ا� @omcahoo.ydr_abdulhassank: ا�(&)� ا'���&و�$ * laithjaafer@yahoo.com : ا�(&)� ا'���&و�$ ** ali_habeeb88@yahoo.com:ا�(&)� ا'���&و�$ ** ـ�ا �: ـ f�e ا��را�� . �e 5$ ھdا ا�(,c إ#&اء درا�� ?�;�� 5$ ا���4ل ا�,&ارة وا�!&)�ن �;��:9 ا�����ھ$ ا���� 5$ أ�("ب أ$45 �23 01("ت ا�.�ا�,&اري ��3ام �:9 ���ھ$ ا���� �"ن 2 ا���ء ا��4�h1 ��;��ا�i j�kا�,�)� ا��� ���lورا91 او &(fe3o4 (80nm) – distilled water) �m n�lا&e 2(φ = 0.3, 0.6, 0.9 %) ��1�o j��k �3م��e ا#&اء �5�l ا��!�رب 5$ #&)�ن اim&ا1$ ���ى ?�د .5$ ا�(,tesla) c 0.3 ,0.2 ,(0.1ا��rة p�dl ���!q ا� q^ �e[� �;��:9 ا�����ھ$ ا�\k& ا�] n( ��;lداد ا��&n( n�lداد ?�د ��;f ).١٩٥٦٢-١١٢٦٢ w/m2( و �ى q -�5&اري ) ٩٨٢٠٢٩٠٠(ر)�"�� ��2 �;��:9 ا���j�k ا�����ھ$ ا�\�l &kن ,e �]?ا�,!��� (% 42.7 ,% 26.4 ,% 5.4)وان ا _��;�(0.3, 0.6, 0.9 %) 2��,e �]?ا�$ وا"�?;` ا� ��c4e 2 9 , (% 0.9)?;` ا��"ا�$ 9 ��(� q!��� (% 43.9,44.3,46)ھ" (tesla 0.1,0.2,0.3)1"#"د !�ل ��kط��$ f1�o �4اره ,�و��(� ا� $����ك )nداد 9 ز)�دة ا���(� ا�,!��� و)nداد 9 ز)�دة �eة ا��!�ل ا����kط��$ و)c4 9 .ز)�دة ?�د ر)�"�� ���q 9 اا���3ام ا��!�ل ا����kط�q'ا c �� .ز)�دة ?�د ر)�"�� (microsoft word \314\310\307\32129-38) al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 14, no. 1, march, (2018) p.p. 29-38 evaluation the mechanical properties of kaolin particulate reinforced epoxy composites jabbar hussein mohmmed department of materials engineering / university of technology/ baghdad email: jabbaraljanaby@yahoo.com (received 26 march 2017; accepted 3 august 2017) https://doi.org/10.22153/kej.2018.08.003 abstract epoxy resin has many chemical features and mechanical properties, but it has a small elongation at break, low impact strength and crack propagation resistance, i.e. it exhibits a brittle behavior. in the current study, the influence of adding kaolin with variable particle size on the mechanical properties (flexural modulus e, toughness gc, fracture toughness kc, hardness hb, and wear rate wr) of epoxy resin was evaluated. composites of epoxy with varying concentrations (0, 10, 20, 30, 40 weights %) of kaolin were prepared by hand-out method. the composites showed improved (e, gc, kc, hb, and wr) properties with the addition of filler. also, similar results were observed with the decrease in particle size. in addition, in this study, multiple regression models were developed by utilizing (spss) package to predict the properties of kaolin reinforced epoxy composites. good agreement was obtained between the predicted and the experimental results. the accuracy of prediction was (89.71%, 80.58%, 85.82%, 92.27%, and 94.49%) for e, gc, kc, hb, and wr, respectively. keywords: epoxy resins, kaolin, particulate composites, spss. 1. introduction the incorporation of particulate fillers into thermosets have a wide use in industry to extend the thermosets and to enhance specific features. fillers usually improve the efficiency and quality of polymeric products. the degree of development relies on the filler origin, shape and particle size, and the volume or weight fraction of filler that will be chosen [1, 2]. the addition of fillers to polymers is a quick and cheap way to change the features of the matrix materials. hence, particulate filled polymer has been, and continue to be, the subject of growing interest in both modern technology and industrial research. in this way, strength, stiffness, toughness and fracture toughness, among other properties can be tailored to the desired values [3]. epoxy resins are one of the most extensive thermoset materials in the world because of their valuable properties, large applications, inert chemical properties, barrier properties and low cost [4]. however, these materials exhibit a low elastic modulus, toughness, and fracture toughness. in this respect, a great deal of effort was devoted to the enhancement of the toughness of epoxy resins in the last few decades aiming at enlarging their field of applications [5]. approaches to improve the toughness of epoxy resins involve mainly the incorporation of solid particles [6-9]. the most useful fillers in epoxy are glass fiber [10], silica powder and aramid fiber [11]. the present work reports the results of the incorporation of kaolin with different contents and different particle sizes into epoxy resins. epoxy/kaolin composite was prepared by hand jabbar hussein mohmmed al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 2938 (2018) 30 out method. in addition to, in this study, the mathematical models for influence of kaolin content and particle size on the flexural modulus, toughness, fracture toughness, hardness, and wear rate were created. 2. experimental work 2.1. materials 2.1.1. preparation of matrix material the matrix material used for current work was epoxy type (cy233) having density in range of (1.1-1.2 g/cm3) at 25˚c and its hardener was (hy956). chemical structure of uncured epoxy is presented in fig.1 [12]. fig. 1. chemical structure of uncured epoxy [12] 2.1.2. preparation of reinforcement material raw kaolin with a density of 2.64 g/cm³, sourced from iraqi national company for geological survey and refinery, was used as reinforcement in the current work. the kaolin powder was milled and sieved by a stack of sieves to obtain different particle sizes. the milled and sieved kaolin was then placed into a ceramic crucible and calcined in an electrical furnace at 700oc for 6 h to remove traces of moisture from the kaolin. hence, the calcined kaolin powder was packaged in a sealed cellophane bag and kept in a desiccator. the typical composition and general properties of kaolin are presented in tables 1, and 2 [13]. table 1, chemical composition of kaolin [13] element wight % sio2 52.48 al2o3 31.31 fe2o3 2.094 tio2 1.43 mgo 0.33 na2o 0.28 cao 0.462 l.o.i 10.93 table 2, general properties of kaolin [13]. properties quantity density, g/cm3 2.64 powder color white melting point, oc 1755 fracture resistance higher 225 mpa thermal properties endothermic at 260 oc isothermic at 980 oc 2.1.3. preparation of composites 17 kaolin reinforced epoxy composite samples were prepared for the current study. particle sizes of (d<8, 18<d<25, 33<d<45, 50<d<62 μm) with varying content of weight percent (0, 10, 20, 30, 40 %wt) of kaolin were used in making samples. hand out method was used to prepare the composite in this work. for preparation the samples, the required amounts of calcined kaolin and epoxy were mixed mechanically for 10 min to ensure suitable and even distribution of kaolin in the mixture phase. afterward, hardener was added in the ratio of 3:1 by weight of epoxy resin and gently but thoroughly stirred manually with the mixture for 15 min to obtain homogeneous mixture and to minimize the gas entrapment. the final mixture was gradually and gently poured into steel molds until the cavity of the molds was completely filled with the composite material. these molds were allowed to cure for 24 h at room temperature. after this, the sample was evacuated from the mold and post cured at 100˚c for 4 hr. finally, the sample was left to cool to lab temperature in the oven itself. 2.2. mechanical tests 2.2.1. flexural test for the three-point flexural test, specimens were manufactured according to astm d790. the span to depth ratio of test samples was 32:1. the tests were performed by using universal testing machine with a crosshead speed of 0.5 mm/min. all the tests were made at room temperature. the flexural modulus e was calculated as follows [14]: where e: young modulus (mpa), l: support span (mm), d: width of sample (mm), b: depth of sample (mm), and m: slope of the tangent to jabbar hussein mohmmed al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 2938 (2018) 31 the initial straight line portion of the loaddeflection curve (n/mm) of deflection. 2.2.2. impact test impact specimens were manufactured according to iso-179 standard suitable to charpy impact instrument. notch depth was equal for all specimens with (1.5 mm), and notch base radius was (0.25 mm). one edge of each specimen was polished so that crack could be readily discerned. the energy absorbed at fracture (uc) can be obtained from impact tests, from which, the value of toughness (gc) was calculated based on the following equation [14]: where: b is depth of sample (mm), d is width of sample (mm), is geometry function. when the ratio between length of sample exposed to impact to cross section of sample equal to 4, the geometry function ( ) can be calculated from the following equation [14]: where: : ratio of notch depth to cross section of sample. in addition to, the values of fracture toughness kc can be calculated from the following equation [14]: 2.2.3. hardness test the hardness tests, using brinell hardness test instrument, were conducted at lab conditions and the measurements were performed at least three different locations on the samples, and the mean value was considered. the indenter was spherical ball with diameter of 5 mm. the test load used in this test was 1500 n and maintained for 15 sec. the resulted diameter from the indentation was measured by microscope, and hb number was calculated as following [14]: where: hb is brinell value, p is applied load (kg), d is ball diameter (mm), d is indention diameter on the sample surface (mm) 2.2.4. wear test wear test was done according to the astm g99 for dry sliding wear test by using a pin on drum tester instrument. the test was performed at a sliding speed of 2 cm/s and pressure of 1mpa at ambient in room conditions. after the end of specified sliding distances (50 m), the testing device was stopped; the surfaces of samples were cleaned thoroughly with brush, and the surface particles (or debris) were removed and the weight loss was determined. the wear rate expressed in (mg/cm) of the material was calculated as follows: where: is wear rate, is weight loss in (mg), and is sliding distance in (m). 2.3. mathematical modeling regression model is a common statistical procedure used for modelling the relationship among several independent variables (variation factors) and a particular dependent (or response functions) variable of interest. regression models can be used to save the time and the cost associated with the development and selection of new composite materials. the basic issue of model building in this project is to create a reliable relationship among mechanical properties and some factors affected on the resultant composite. the independent variables (explanatory factors) used in this work to predict the dependent variables, composite properties (e, gc, kc, hb, and wr), are presented in table 3. the available experimental data (table 4) were randomly divided into two groups; the training data group (table 5) which found for prediction model building and the testing data group (table 6) which found to test the flexibility and the validity of the prediction model. jabbar hussein mohmmed al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 2938 (2018) 32 table 3, definition and values of independent variables used in regression equation. designations of independent variable variable name value kaolin concentration (% wt) 0,10, 20, 30, 40 particle size (μm) d ≤ 8, 18 ≤ d ≤ 25, 33 < d < 45, 50 < d < 62 table 4, original experimental data for predicted and measured properties of epoxy composite. no. kaolin added (%) particle size (μm) measured e (gpa) predicted e (gpa) measured gc (kj/m2) predicted gc (kj/m2) measured kc (mpa√m) predicted kc (mpa√m) measured hb predicted hb measured wr (mg/cm) predicted wr (mg/cm) 1 0 0 1.5 1.72652 1.16 1.09822 1.29 1.47088 13.02 13.12127 17.34 14.0044 2 10 d ≤ 8 2.93 2.58406 1.55 1.52185 2.15 1.98661 17.12 16.71474 8.2 11.10932 3 20 d ≤ 8 3.46 3.52369 1.95 2.12716 2.44 2.68983 19.49 21.72005 7.46 8.91932 4 30 d ≤ 8 4.28 4.46332 2.63 2.73246 3.22 3.39305 26.55 26.72537 6.88 6.72932 5 40 d ≤ 8 5.66 5.40295 3.5 3.33776 4.64 4.09627 33.89 31.73069 5.72 4.53931 6 10 18 ≤ d ≤ 25 2.77 2.44041 1.3 1.20393 2 1.65851 16.51 14.24399 8.98 10.43982 7 20 18 ≤ d ≤ 25 3.08 3.38005 1.82 1.80924 2.34 2.36173 18.43 19.24931 8.12 8.81419 8 30 18 ≤ d ≤ 25 4.11 4.31968 2.25 2.41454 2.99 3.06495 22.92 24.25463 7.22 7.18855 9 40 18 ≤ d ≤ 25 5.31 5.25931 3.11 3.01984 3.42 3.76817 29.09 29.25995 6.01 5.56291 10 10 33 < d < 45 2.53 2.26598 1.12 0.81789 1.01 1.2601 13.13 11.2438 9.54 962686 11 20 33 < d < 45 2.99 3.20561 1.35 1.42319 1.82 1.96332 15.44 16.24912 8.66 8.68653 12 30 33 < d < 45 3.82 4.14524 1.78 2.02849 1.98 2.66654 19.79 21.25443 8.06 7.74619 13 40 33 < d < 45 4.76 5.08487 2.15 2.6338 3.01 3.36976 25.35 26.25975 7.55 6.80586 14 10 50 < d < 62 1.58 2.09155 0.79 0.43184 0.99 0.86169 9.62 8.24361 9.97 8.8139 15 20 50 < d < 62 2.87 3.03118 1.18 1.03714 1.41 1.56491 12.98 13.24892 8.87 8.55887 16 30 50 < d < 62 3.95 3.97081 1.47 1.64245 2.11 2.26813 17.35 18.25424 8.11 8.30384 17 40 50 < d < 62 4.43 4.91044 1.88 2.24775 2.89 2.97135 21.78 23.25956 7.21 8.04881 table 5, training data for properties of epoxy composite. no. kaolin added (%) particle size (μm) measured e (gpa) predicted e (gpa) measured gc (kj/m2) predicted gc (kj/m2) measured kc (mpa√m) predicted kc (mpa√m) measured hb predicted hb measured wr predicted wr 1 0 0 1.5 1.72652 1.16 1.09822 1.29 1.47088 13.02 13.12127 17.34 14.0044 2 10 d ≤ 8 2.93 2.58406 1.55 1.52185 2.15 1.98661 17.12 16.71474 8.2 11.10932 3 20 d ≤ 8 3.46 3.52369 1.95 2.12716 2.44 2.68983 19.49 21.72005 7.46 8.91932 4 30 d ≤ 8 4.28 4.46332 2.63 2.73246 3.22 3.39305 26.55 26.72537 6.88 6.72932 5 40 d ≤ 8 5.66 5.40295 3.5 3.33776 4.64 4.09627 33.89 31.73069 5.72 4.53931 6 10 18 ≤ d ≤ 25 2.77 2.44041 1.3 1.20393 2 1.65851 16.51 14.24399 8.98 10.43982 7 20 18 ≤ d ≤ 25 3.08 3.38005 1.82 1.80924 2.34 2.36173 18.43 19.24931 8.12 8.81419 8 30 18 ≤ d ≤ 25 4.11 4.31968 2.25 2.41454 2.99 3.06495 22.92 24.25463 7.22 7.18855 9 40 18 ≤ d ≤ 25 5.31 5.25931 3.11 3.01984 3.42 3.76817 29.09 29.25995 6.01 5.56291 jabbar hussein mohmmed al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 2938 (2018) 33 table 6, testing data for properties of epoxy composite. no. kaolin added (%) particle size (μm) measured e (gpa) predicted e (gpa) measured gc (kj/m2) predicted gc (kj/m2) measured kc (mpa√m) predicted kc (mpa√m) measured hb predicted hb measured wr predicted wr 1 10 33 < d < 45 2.53 2.26598 1.12 0.81789 1.01 1.2601 13.13 11.2438 9.54 962686 2 20 33 < d < 45 2.99 3.20561 1.35 1.42319 1.82 1.96332 15.44 16.24912 8.66 8.68653 3 30 33 < d < 45 3.82 4.14524 1.78 2.02849 1.98 2.66654 19.79 21.25443 8.06 7.74619 4 40 33 < d < 45 4.76 5.08487 2.15 2.6338 3.01 3.36976 25.35 26.25975 7.55 6.80586 5 10 50 < d < 62 1.58 2.09155 0.79 0.43184 0.99 0.86169 9.62 8.24361 9.97 8.8139 6 20 50 < d < 62 2.87 3.03118 1.18 1.03714 1.41 1.56491 12.98 13.24892 8.87 8.55887 7 30 50 < d < 62 3.95 3.97081 1.47 1.64245 2.11 2.26813 17.35 18.25424 8.11 8.30384 8 40 50 < d < 62 4.43 4.91044 1.88 2.24775 2.89 2.97135 21.78 23.25956 7.21 8.04881 3. results and discussion 3.1. experimental work 3.1.1. flexural modulus figure 2 shows the variation of flexural modulus of the material with kaolin filler content for different particle sizes. generally, the flexural modulus (e) is referred to the relative stiffness of composite [15]. thus, the growing in e value with increasing filler loading is expected since the addition of filler improves the stiffness of composites. this enhancing can be attributed to the stiff nature of filler. a similar observation was made by many researchers [13, 16-17]. the rate of increasing in e values was comparable to the increasing in weight fraction of kaolin and the decrease in particle size. therefore, it was conformed that the total area available to deformation stress played an important role. the increasing in e values is mainly attributed to the restriction of chain mobility, this can be explained by plastic deformation mechanism. capability of any material to plastic deformation is mainly specified by the mobility of the molecular chain (molecular motion) to occur under applied force. the existence of solid particles like kaolin in this case has restricted the mobility of the molecular chain to pass each other and the orientation that consequently resulted in increase in rigidity (stiffness). 0 1 2 3 4 5 6 0 10 20 30 40 y o u n g m o d u lu s, g p a kaolin content, % d ≤ 8 18 ≤ d ≤ 25 33 < d < 45 50 < d < 62 fig. 2. variation in flexural modulus of different particle sizes and weight fractions of kaolin 3.1.2. toughness and fracture toughness the variation of toughness (gc) and fracture toughness (kc) for the composites with filler loading for different particle sizes are presented in figures (3, and 4), respectively. it can be seen that the gc and kc increases, as the kaolin content increases and the particle size decreases. the maximum improvement is attained with 40%wt kaolin and (d<8μm) particle size, and represents more than (203) % and (259) % in comparison with gc and kc of neat resin, respectively the improvement of impact properties was reported in literature with different modifier [16, 18]. jabbar hussein mohmmed al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 2938 (2018) 34 0 0.5 1 1.5 2 2.5 3 3.5 4 0 10 20 30 40 t o u g h n e s s , k j/ m 2 kaolin content, % d ≤ 8 18 ≤ d ≤ 25 33 < d < 45 50 < d < 62 fig. 3. variation in toughness of different particle sizes and weight fractions of kaolin 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 0 10 20 30 40 f ra c tu re t o u g h n e s s, m p a √ m kaolin content, % d ≤ 8 18 ≤ d ≤ 25 33 < d < 45 50 < d < 62 fig. 4. variation in fracture toughness of different particle sizes and weight fractions of kaolin the gc and kc improvement by the addition of kaolin particles can be due to the formation of small sized crystallites, i.e. spherulites, and the capacity to absorb much energy by the enlarge of portion of matrix. also, this enhancing can be explained by the crack pinning mechanism [19]. impact strength is an indication of tolerability for a sudden impact. as the composites are exposed to the impact load, rapid crack propagation is initiated through the material. when such crack propagation encounters solid particles in the filled composite, the filler can absorb the energy and stop the crack propagation. in other hand, nakagawa and sano [20] have shown the existence of small and fine particles dispersed into the matrix makes plastic deformation more easy. so, during the fracture of the composite in which the solid filler is fine and well dispersed, i.e., in which the material is more homogeneous, the stress will have to be bigger to begin a micro crack on particles and the impact energy will strongly be absorbed by plastic deformation. hence, finer particles lead to better impact properties of the composite. on the other hand, the increasing of the kaolin content to higher levels (beyond 40%wt) may be brought the inverse effects on the properties because of the brittleness problem. 3.1.3. hardness it is clearly seen from figure (5) that the hardness increases with the decrease in particle size and increase in weight percent of filler. the addition of kaolin filler improves the hardness value of composite material because of the increasing in the resistance strength of polymer to plastic deformation. the results agree well with those obtained by saleh and mustafa [13], who showed that the hardness increases with increasing weight percent and decreasing particle size. 0 5 10 15 20 25 30 35 40 0 10 20 30 40 h a rd n e ss , h b kaolin content, % d ≤ 8 18 ≤ d ≤ 25 33 < d < 45 50 < d < 62 fig. 5. variation in hardness of different particle sizes and weight fractions of kaolin 3.1.4. wear rate the results presented in fig. (6) show that the wear rate was less when reinforcing the epoxy resin with kaolin particles in the range of (0-40%). this enhancement may be explained by that the kaolin particles will absorb a portion of applied stress and heat generated by friction as a result of slip between the surface of samples and the surface of the rotating disk. thus, the applied stress and heat generated will be distributed on the matrix and reinforcing particles, and this will improve the ability of the epoxy resin to resist the wear. also, the same trend was observed with the decrease in the particle size. this is because the increasing in particle size increases the interface jabbar hussein mohmmed al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 2938 (2018) 35 surface and this leads to impede the process of transfer of stresses and heat of the matrix to the reinforcing particles, and then increases the concentration of stress, heat, thus this will increase the wear rate with increasing the particle size. 0 2 4 6 8 10 12 14 16 18 20 0 10 20 30 40 w e a r r a te , m g / c m kaolin content, % d ≤ 8 18 ≤ d ≤ 25 33 < d < 45 50 < d < 62 fig. 6. variation in wear rate of different particle sizes and weight fractions of kaolin 3.2. results and discussion of mathematical model regression models of composite properties were developed from the processing of experimental results. these analyses were performed by using spss software. the following equations represent the relationship between composite properties and all independent variables involved in this work: where: : flexural modulus, : toughness, : fracture toughness. all equations confirmed a high value of multiple correlation coefficient r which were (0.981, 0.989, 0.953, 0.976, and 0.851) for equations (7, 8, 9, 10 & 11) respectively. the error value of the training data group was (7.25%, 4.72%, 8.84%, 5.13%, and 14.43%) for (e, gc, kc, hb, and wr), respectively and for the testing data group was (10.29%, 19.42%, 14.18%, 7.73%, and 5.51%) for (e, gc, kc, hb, and wr), respectively. this reveals that the statistical model could predict the epoxy composite properties with about (92.75%, 95.28%, 91.16%, 94.87%, and 85.57%) accuracy of the training data set and approximately (89.71%, 80.58%, 85.82%, 92.27%, and 94.49%) accuracy of the testing data set for properties (e, gc, kc, hb, and wr), respectively. figures (5, 6, 7, 8, and 9) present the comparison between the predicted and experimental values of 17 original data for mechanical properties, respectively by (spss) package. it can be noticed from these figures that the predicted values are in a close match with the experimental values for all properties. 5.004.003.002.00 e_predicted 6.00 5.00 4.00 3.00 2.00 1.00 e _ m e a s u re d r sq linear = 0.947 fig. 7. experimental and predicted values of flexural modulus 3.002.001.000.00 gc_predicted 3.50 3.00 2.50 2.00 1.50 1.00 0.50 g c _ m e a s u re d r sq linear = 0.93 fig. 8. experimental and predicted values of toughness jabbar hussein mohmmed al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 2938 (2018) 36 4.003.002.001.00 kc_predicted 5.00 4.00 3.00 2.00 1.00 k c _ m e a s u re d r sq linear = 0.913 fig. 9. experimental and predicted values of fracture toughness 35.0030.0025.0020.0015.0010.005.00 hb_predicted 35.00 30.00 25.00 20.00 15.00 10.00 5.00 h b _ m e a s u r e d r sq linear = 0.959 fig. 10. experimental and predicted values of hardness 16.0014.0012.0010.008.006.004.00 wr_predicted 17.50 15.00 12.50 10.00 7.50 5.00 w r _ m e a s u re d r sq linear = 0.724 fig. 11. experimental and predicted values of wear rate. 4. conclusions from the experimental results it can conclude the following: • the addition of kaolin particles into epoxy resin can remarkably alter the material’s mechanical properties. the material properties (e, gc, kc, hb, and wr) increase with the increasing filler content. • the properties of epoxy composite decreased as the particle size of kaolin increased. • the multiple regression models could predict the properties of epoxy composite with higher accuracy for different kaolin additions, and particle sizes. 5. references [1] y. wang, and j.j. wang, (1999), “shear yield behavior of calcium carbonate-filled polypropylene”, polymer eng. & sci., vol. 39, no.1, pp. 190–198. [2] i. plesa, p. v. notingher, s. schlögl, c. sumereder, and m. muhr, (2016), “properties of polymer composites used in highvoltage applications “, polymer journal, vol. 8, no. 126, pp. 1-63. [3] e. g. guerica, j. i. eguiazabal, and j. nazabal, (1998), “influence of molding conditions and talc content on the properties of polypropylene composites”, european polymer journal, vol. 34, no. 98, pp. 1213– 1219. [4] m. s. bhatnagar, (1993), “epoxy resins from 1980 to date”, part 1, polymer-plastics technolgy and eng. journal, vol. 32, no. 12, pp. 53-113. [5] s. r. lu, x. e. l. xiao, l. pan, f. z. tan, and j. h. yu, (2014), “enhanced thermal and mechanical properties of epoxy composites by mixing thermotropic liquid crystalline epoxy grafted graphene oxide”, express polymer letters, vol.8, no.7, pp. 467–479. [6] a. c. moloney, h. h. kausch, and h. r. stieger, (1983), “the fracture of particulatefilled epoxy resin”, journal of materials science, vol. 18, no. 1, pp. 208 – 216. [7] j. spanoudakis, and r., j. young, (1984), “crack propagation in a glass particulatefilled epoxy resin”, journal of materials science, vol. 19, no. 2, pp. 473 – 486. [8] s. fellahi, n. chikhi, and m. bakar, (2001), “modification of epoxy resin with kaolin as jabbar hussein mohmmed al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 2938 (2018) 37 a toughening agent”, journal of applied polymer sci., vol. 82, no. 4, pp. 861 – 878. [9] b. m. deya’a, f. m. hussien, and i. g. dway, (2011), “studying the impact strength of (epoxy with tio2 and mgo) composite”, eng. and tech. journal, vol. 29, no. 10, pp. 1971-1978. 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[14] a. m. hameed, (2000), "study of the effect of reinforcement with fibers on some physical characteristics of composite material", m.sc. thesis, university of technology. [15] v. shah, (2007), “handbook of polymer testing and failure analysis”, 3rd edition, new jersey, john wily & sons, inc., 648. [16] h. v. ramakrishna, and s. k. rai, (2006), “utilization of granite powder as a filler for polybutylene terepthalate toughened epoxy resin”, journal of minerals & materials characterization & engineering, vol. 5, no.1, pp 1-19. [17] e. suryani, e. s. abdul rashid, k. ariffin, and c. c. kooi, (2006), “the flexural and morphological properties of α-alumina filled epoxy composites”, malaysian polymer journal, vol 1, no. 1, pp. 25-38. [18] s. bose, and p. a. mahanwar, (2004), “effect of particle size of filler on properties of nylon-6”, journal of minerals & materials characterization & engineering, vol. 3, no.1, pp. 23-31. [19] f. f. lange, and k. c. radford, (1971), “fracture energy of an epoxy composite system”, journal of materials science, vol. 6, no, 9, pp.1197–1203. [20] h.nakagawa, and h.sano, (1982), polym. prepr., vol. 26, p.249. )2018( 29-38، صفحة 1د، العد14دجلة الخوارزمي الهندسية المجلم جبار حسين محمد 38 الكاؤولينبدقائق االيبوكسي المقواة لمتراكبات الميكانيكية الخواص تقييم جبار حسين محمد قسم هندسة المواد / الجامعة التكنولوجية jabbaraljanaby@yahoo.comالبريد االلكتروني: الخالصة للصدمة ضعيفة ومقاومة محدودة مطيلية لكتمي نفسه الوقت في لكنه جداً، مهمةال كيميائيةالو ميكانيكيةال خواصيد من الالعد االيبوكسي راتنجيمتلك ً بديي آخر بمعنى الشق، ولتوسع ً سلوكا معامل (الميكانيكية الخواص على مختلفة حبيبية بأحجام الكاؤولين اضافة تأثير يموتق تم البحث هذا في .هشا ، ٣٠، ٢٠، ١٠، ٠من االيبوكسي بتراكيز مختلفة ( متراكبات تحضير تم لراتنجات االيبوكسي. )البلى ومعدل الصالدة، الكسر، متانة المتانة، االنحناء، الصالدة، من الوزن) من الكاؤولين باستخدام طريقة القولبة اليدوية. اظهرت المتراكبات تحسنا في خواص (معامل االنحناء، المتانة، متانة الكسر، %٤٠ البحث تطوير موديل انحدار متعدد هذا في ايضا كما تمالحبيبي. الحجم بتقليل وتمت مالحظة النتائج نفسهاومعدل البلى) عند اضافة حشوة الكاؤولين. تم الحصول على توافق جيد عند مقارنة القيم العملية و بالكاؤولين المقواة االيبوكسي متراكبات بخواص التنبؤ ) من اجلspssبرنامج ( باستعمال الصالدة، الكسر، متانة المتانة، االنحناء، ) لمعامل%٩٤٫٤٩، و%٩٢٫٢٧، %٨٥٫٨٢، %٨٠٫٥٨، %٨٩٫٧١حوالي ( التنبؤ دقة كانت فقد والمتنبئة. .التوالي على البلى ومعدل 8492 al-khwarizmi engineering journal, vol. 11, no. 1, p. experimental and theoretical investigation of impact dynamic hani aziz ameen *department **department (received abstract the low velocity axial impact of thin the phenomenon is known as dynamic progressive on dynamic plastic buckling of circular cylindrical shells under axial impact are carried out by designing and building a device to study the behavior of ck45 under low speed impact (3.8 theoretical (abramowicz model) for the energy absorbers and dynamic load under different velocities. the results show that when the velocity of impact increases, the value of the dynamic crushing stress for elastoplastic collapse deformation, a tube initially goes through elastic deformation, then plastic deformation occurs, after that the tube goes through plastic collapse. as the force decreases, the displacement still increases model for dynamic impact shows well coincide with discrepancy 45%. it can be indicated that the increasing in the velocity or kinetic energy leads to increase in the load in the practical part while it seems to be horizontally linear in th theoretical part. keywords: impact, dynamic plasticity, abramowicz model, energy absorbers,ck45 1. introduction thin wall circular cylindrical shells are used as energy absorbing device. the energy absorption can be represented by collapsing plastically of thin wall tube in axial compression that converted kinetic energy into plastic deformation deformable solids. the energy absorption divided into energy absorbing by friction and by deformation of solids. the use of metal components as energy absorbers which permits large plastic strains without failure. plastic deformation and specially plastic buckling of tubes is an effective mechanism by which energy can be dissipated [1]. when the circular thin tubes are subjected to axial impact at speed sufficient to cause a moderate amount of plastic deformation axisymmetric bucking occurs [2]. a developed theoretical analysis for axisymmetric crushing of thin– walled cylindrical shell khwarizmi engineering journal, vol. 11, no. 1, p.p. 8492 (2015) experimental and theoretical investigation of impact dynamic plasticity for ck45 hani aziz ameen* ahlam abd alameer department of dies and tools engineering/ technical collegebaghdad department of electro mechanical engineering/ university of technology haniazizameen@yahoo.commail: -e* ahlamabdalamir@yahoo.commail: -e** (received 25 march 2014; accepted 2 november 2014) the low velocity axial impact of thin-walled circular ck45 tubes is taken. the wrinkles develop progressively and the phenomenon is known as dynamic progressive buckling. in the present paper, experimental and theoretical studies on dynamic plastic buckling of circular cylindrical shells under axial impact are carried out by designing and building a device to study the behavior of ck45 under low speed impact (3.8-6.25)m/s. the work consists of experimental and theoretical (abramowicz model) for the energy absorbers and dynamic load under different velocities. the results show that when the velocity of impact increases, the value of the dynamic crushing stress for ck45 will increase, also for elastoplastic collapse deformation, a tube initially goes through elastic deformation, then plastic deformation occurs, after that the tube goes through plastic collapse. as the force decreases, the displacement still increases model for dynamic impact shows well coincide with discrepancy 45%. it can be indicated that the increasing in the velocity or kinetic energy leads to increase in the load in the practical part while it seems to be horizontally linear in th act, dynamic plasticity, abramowicz model, energy absorbers,ck45. thin wall circular cylindrical shells are used as energy absorbing device. the energy absorption can be represented by collapsing plastically of thin wall tube in axial compression that converted kinetic energy into plastic deformation energy in deformable solids. the energy absorption divided into energy absorbing by friction and by deformation of solids. the use of metal components as energy absorbers which permits large plastic strains without failure. plastic y plastic buckling of tubes is an effective mechanism by which energy can be dissipated [1]. when the circular thin tubes are subjected to axial impact at speed sufficient to cause a moderate amount of plastic deformation axisymmetric bucking occurs [2]. alexander [3] r axisymmetric walled cylindrical shell subjected to axial loading and he was the first who presented a mathematical simulation of the crushing problem for tubular members and collapsing in the axisymmetric. abramowitz and jones [4] have improved the alexander solution by introducing a correction for the effective strain rate. gu et al [5] used the energy criterion to study the radial buckling of cylindrical shells. murase and jones [6] investigated some experiments on aluminum shells subjected to high impacts also registered progressive buckling. abramowicz and jones [7] showed that a variety of dynamic buckling response of axially loaded shells is caused by coupling of the inertia with the inelastic material properties. recent development in axisymmetric buckling of circular cylindrical shells have generated the effects of stress wave propagation [8]. however, the type of buckling depends on the magnitude of the impact veloci al-khwarizmi engineering journal 2015) experimental and theoretical investigation of impact dynamic meer** baghdad of technology walled circular ck45 tubes is taken. the wrinkles develop progressively and buckling. in the present paper, experimental and theoretical studies on dynamic plastic buckling of circular cylindrical shells under axial impact are carried out by designing and building a 6.25)m/s. the work consists of experimental and theoretical (abramowicz model) for the energy absorbers and dynamic load under different velocities. the results show ck45 will increase, also for elastoplastic collapse deformation, a tube initially goes through elastic deformation, then plastic deformation occurs, after that the tube goes through plastic collapse. as the force decreases, the displacement still increases. abramowicz model for dynamic impact shows well coincide with discrepancy 45%. it can be indicated that the increasing in the velocity or kinetic energy leads to increase in the load in the practical part while it seems to be horizontally linear in the subjected to axial loading and he was the first who presented a mathematical simulation of the crushing problem for tubular members and the axisymmetric. abramowitz and jones [4] have improved the alexander solution by introducing a correction for the effective strain rate. gu et al [5] used the energy criterion to study the radial buckling of cylindrical shells. murase tigated some experiments on aluminum shells subjected to highvelocity impacts also registered progressive buckling. abramowicz and jones [7] showed that a variety of dynamic buckling response of axially loaded shells is caused by coupling of the inertia effect with the inelastic material properties. recent development in axisymmetric buckling of circular cylindrical shells have generated the effects of stress wave propagation [8]. however, the type of buckling depends on the magnitude of the impact velocity and the value of hani aziz ameen al-khwarizmi engineering journal, vol. 11, no. 1, p.p. 8492 (2015) 85 the striking mass. high velocity impacts cause dynamic plastic buckling , while the same shell collapses progressively for lowvelocity impacts. the initial dynamic response of a shell for a high velocity impact is more complex than for progressive buckling, but the subsequent buckling behavior can be developed progressively with time. the behavior of a tube crushed axially between rigid plates depends on its parameters , the ratio of length to mean diameter (l/d) and the ratio of mean diameter to thickness (d/h) as well as properties of material (yield stress and strain rate) [9]. in the present work, the dynamic buckling of steel ck45 thin tube under quasi-static and impact load is investigated experimentally and theoretically. 2. the practical aspect 2.1. metal selection steel ck45 according to aisi is chosen. its chemical analysis is indicated in table-1. the chemical composition was conducted by arl spectrometer. the mechanical properties is measured by instron1195 apparatus for ck45 as indicated in table-2-. table 1, chemical composition of the used metal (ck45). c% mn% p% s% fe% measured value 0.42-0.5 0.6-0.9 ≤0.04 0.05 98.5-98.98 standard value 0.472 0.567 0.03 rem table 2, mechanical properties of the used metal (ck45). 2.2. specimen preparation circular section steel alloy (ck45) tubes were used. these tubes were cut to equal lengths by cutter machine. fig.(1) shows the shape and dimensions of the specimens used in this study. the specimen dimensions are thickness (t ) =1mm , inner diameter (dinner) = 16 mm , length (l) = 30 mm according to the standard din2250. [4]. fig. 1. specimen dimension. 2.3. impact test rig an impact test rig was constructed to impact the specimens at different velocities. fig.(2) shows the impact test rig. theexperimental tests were conducted on drop hammer rig in fig.(2) , this rig has mass 22.92 kg , the velocity of the dropping mass was measured experimentally by the test rig end compared within the calculated velocity using � = �2��, where h is the height of the dropping mass , the discrepancy of the results was about 5% (h was taken from (0.75-2) m and g=9.81 m/sec2). � [mpa] � [mpa] e (gpa) elongation hardness vickers measured value 685 655 229 12% 196 standard value 515 610 209.5 190 hani aziz ameen al-khwarizmi engineering journal, vol. 11, no. 1, p.p. 8492 (2015) 86 fig. 2. show the impact test rig. 2.4. static test (compressive test) a load of 50 kn at 1mm/min speed was used as a compressive head. the aim of this test is to obtain the mode of deformation (concertina buckling). the results of the above test can be illustrated as in table(3), fig.(3) shows the relationship between the stress and strain and fig.(4) shows a specimen before and after testing. fig.(5) shows a typical forcedisplacement curve for a tube crushed by a moving mass. table 3, results of static compressive tests for ck45. p (kn) δ mm p (kn) δ (mm) p (kn) δ (mm) 0 0 21.38 4.487 32.75 10.919 6.11 0.2992 23.414 5.08 21.719 11.219 15.27 0.5982 22.736 5.534 20.693 11.967 18.32 0.748 21.38 5.833 21.032 13.462 21.38 1.0472 19.337 6.731 19.676 14.359 24.43 1.1968 15.27 7.927 21.888 15.406 27.819 1.9448 22.736 8.975 21.38 15.706 25.786 2.244 23.75 9.27 20.693 16.454 21.38 2.8424 23.75 9.27 23.075 19.202 17.643 3.44 21.38 10.02 hani aziz ameen al-khwarizmi engineering journal, vol. 11, no. 1, p.p. 8492 (2015) 87 fig. 3. a typical stress-strain curve for a tube crushed by a moving mass. fig. 4. shows a specimen before and after testing. table (4) shows the mean load and energy absorbed by the specimen at failure with mode of deformation. table 4, static results at failure. failure es(j) ∆∆∆∆lf (mm) pm f (kn) mode complete damage of specimen 422.8 19.334 21.868 concertina buckling the energy absorbed was calculated using the equation es=(pm f). (∆∆∆∆l f) …(1) where : ∆∆∆∆l f : deformation at failure (mm) pmf : mean load at failure (kn) es: energy absorbed by the specimen (joule) fig. 5. shows a typical forcedisplacement curve for a tube crushed by a moving mass. fig.(5) shows a typical forcedisplacement curve for a tube crushed by a moving mass. it is seen that tube initially goes through elastic deformation as shown in the range (a). this range behavior as the tensile or compressive test obeys to hook’s law. then plastic deformation occurs as seen in range (b). after that, the tube goes through plastic collapse, as the force decreases while the displacement still increases range (ii) in fig.(5). this behavior shows approximately three folds when the first failure (folding) of the tube occurs. in an axial test, the tube gets crushed into several folds. after the first folding is finishes the second one occurs, then the third one. due to the second folding, another elastoplastic deformation and plastic collapse occurs. the sequential deformations are repeated until the moving mass reaches its maximum displacement, unless a dramatic column buckling mode during the crushing test, this behavior of the metal used is impolitely coincide with the work of references [10] and [11]. fig.(3) represented the energy absorbing capability of the impact limiter is controlled by several factors such as energy absorbing capacity, mean crush load, maximum crush load, crush load amplitude, etc. the impact energy absorber should be evaluated for some typical aspects collapse load, energy absorption, and collapse space efficiency. 2.5. impact test ten specimen are tested at different speeds (3.834 – 6.25) m/s by using weight of 22.92 kg. the results can be illustrated as in table (5). hani aziz ameen al-khwarizmi engineering journal, vol. 11, no. 1, p.p. 8492 (2015) 88 table 5, dynamic results of ck45 under 22.92 kg. h m vo m/s lo mm lf mm δ mm pd m kn k.e j mode of deformation 0.75 3.834 29.9 25.3 4.6 36.62 168.456 concertina 0.75 3.834 29.9 25.0 4.9 34.378 168.105 concertina 0.875 4.141 29.9 23.7 6.3 31.19 196.51 concertina 1 4.427 30 22.1 7.9 28.43 224.61 concertina 1.25 4.949 30 17.6 12.4 22.64 280.77 concertina 1.375 5.19 29.9 16.2 13.7 22.54 308.8 concertina 1.5 5.422 30 15 15.0 22.46 336.924 concertina 1.625 5.643 29.9 13.5 16.4 22.23 364.68 concertina+ diamond 1.75 5.853 30 12.7 17.72 21.17 392.99 concertina+ diamond 1.875 6.062 29.9 9.93 18.96 21.29 421.155 concertina 2 6.25 30 8.8 21.2 21.2 448.84 diamond 2 6.25 30 8.9 21.1 21. 27 448.84 concertina 2 6.25 29.9 7.6 22.3 20.127 448.84 diamond 3. the theoretical aspect (abramowicz model) bramowicz model is an improvement of alexander’s theoretical analysis [12],[4], for axisymmetric crushing of axially load cylindrical shell (concertina ,ode) and estimates of the effective crushing distance and influence of material rate effects. from fig.(6), the circumferential plastic hinges during the crushing of one lobe is : fig. 6. idealized model of deformation for axisymmetric concertina mode of an axially compressed circular tube. �� = 4���(�� + ℎ) …(2) which is identical to alexander [12-14]. the stretch plastic hinges is �� = 2����ℎ�(1 + � ��) …(3) the mean crushing load pm is found from � . 2ℎ = �� +�� …(4) so, "# $% = 20.79 ( �� * )+., + 11.9 …(5) � � = 1.76( � ��)+., …(6) effective crushing distance is [12]: ./ �� = 0.86 − 0.568 ( * ��)+., …(7) and "#3 "# = 1 + 4 56 �.7889 +.7: …(8) ;6 = �5<=#./ …(9) where;> can be found from the following equation ;> = 0.88( ���)+., …(10) where � � can be found from eq.(6) � = =� … (11) in the present work , t=1 mm , din=16 mm , ��= 685 mpa �� = ?@.* a √� …(12) the dynamic load � c = � d1 + 4 56 �.7889 +.7:e …(13) hani aziz ameen al-khwarizmi engineering journal, vol. 11, no. 1, p.p. 8492 (2015) 89 where;6 can be found from eq.(9) and � . from eq.(5) and kinetic energy f = � c . g …(14) 4. results and discussion the low velocity axial impact of thin-walled circular tubes is taken as quasi-static and the influence of inertia forces is, therefore, ignored. the wrinkles develop progressively and the phenomenon is known as dynamic progressive buckling. in the present study, most of the ck45 steel tubes suffer extensional crushing. many crushed steel tubes have a mixed type of crushing which consists of type i and type ii modes and a general mixed collapse mode is studied. for low velocity impact with large striking masses, the theoretical predictions for dynamic progressive axial crushing of thin-walled circular tubes gives a reasonable agreement with the corresponding experimental results provided the effective crushing distance is recognized and with the average discrepancy about 45%. a theoretical analysis using the basic collapse elements developed by abramowicz is reported by abramowicz and jones [4] for the progressive buckling of thin-walled circular box columns subjected to axial loads, which considers the effective crushing distance, together with the influence of material strain rate sensitivity. table (6) shows the dynamic mean load theoretical and experimental results with velocity for ck45 steel tube under 22.92 kg dropping mass . table 6, dynamic mean load (theoretical & experimental) with velocity. vo m/sec k.e j pd m (th) kn pd m(exp.) kn discrepancy % 3.834 168.105 36.028 6.6911 81% 4.141 196.51 36.047 8.274 77% 4.427 224.61 36.0593 10.16 72% 4.949 280.77 36.0877 15.95 56% 5.19 308.8 36.101 19.06 47% 5.422 336.924 36.114 22.46 38% 5.643 364.68 36.1267 27.1 25% 5.853 392.99 36.192 30.9 15% 6.062 421.155 36.15 32.41 10% 6.25 448.84 36.163 34.219 5% and fig.(7) shows the relation between dynamic mean load (theoretical and experimental) and velocities. it can be indicated that the increasing in the velocity leads to increase in the load in the practical part while it seems to be horizontally linear in the theoretical part, this is due to the assumption of the theoretical model that wb , the energy dissipated due plastic bending and wc , the energy dissipated in stretching under substantially uniform tensile yield hoop stress in the metal between the hinges and also assuming the material of the cylinder is rigid-perfectly plastic, then using the notion obvious from fig.(6), to attain complete collapse of one hinges system (i.e. θ increasing from zero to π/2 ). fig. 7. shows the relation between dynamic mean load (theoretical and experimental) and velocities. fig.(8) represents the results of load (p) which was plotted as a function of kinetic energy (k.e), 5 10 15 20 25 30 35 40 3 3.5 4 4.5 5 5.5 6 6.5 p (k n ) vo(m/sec p(th)kn p(exp)k n hani aziz ameen al-khwarizmi engineering journal, vol. 11, no. 1, p.p. 8492 (2015) 90 it is found that p varying with the kinetic energy, and give the same results that were obtained by p and v, this is because to that the kinetic energy extremely related with velocity as :f. h.= i�j��, hence the results are the same at which obtained between p and v. fig.(9) shows the relation between kinetic energy (theoretical & experimental) with velocity also results are compared with ayad [15]. fig. 8. relation between dynamic mean load (theoretical & experimental) and kinetic energy. fig. 9. relation between kinetic energy (theoretical & experimental) with velocity. the energy absorbing capability of the impact limiter is controlled by several factors such as energy absorbing capacity, mean crush load, maximum crush load, crush load amplitude, etc. the impact energy absorber should be evaluated for some typical aspects collapse load, energy absorption, and collapse space efficiency. the collapse load is defined as that load required to cause a significant permanent deformation of a particular section of the impacted body. often, the forces needed to cause significant deformation are of interest since they are relevant to the safety of the contents in the package or the passengers in the vehicle. the amount of deformation is not usually critical at the collapse load. therefore, the crushing load of cylindrical tube fluctuates with the proceeding of folding. for a practical energy absorber, as shown in fig.(3), the area under the stress-strain curve for a structure represents the energy absorbed by the structure. the theoretical predictions for dynamic progressive axial crushing of thin-walled circular tubes gives a reasonable agreement with the corresponding experimental results provided the effective crushing distance is recognized for ck45 steel case. 5. conclusions 1. for elastoplastic collapse deformation, a tube initially goes through elastic deformation , then plastic deformation occurs, after that the tube goes through plastic collapse. as the force decreases, the displacement still increases. 2. abramowicz model for dynamic impact shows well coincide with discrepancy 45%. 3. it can be indicated that the increasing in the velocity or kinetic energy leads to increase in the load in the practical part while it seems to be horizontally linear in the theoretical part notation d diameter of tube r radius of tube t thickness of tube l original length of tube pm theoretical static crushing load �� yield stress �k ultimate tensile stress � c theoretical mean dynamic crushing load � impact velocity of striking mass e elastic modulus g acceleration of gravity es energy absorption h collapsed length of tube g deformation 0 5 10 15 20 25 30 35 40 100 300 500 p (k n ) k.e(j) pth pexp 100 150 200 250 300 350 400 450 500 3 4 5 6 7 8 k .e (j ) v(m/sec) presen t abram owicz ayad hani aziz ameen al-khwarizmi engineering journal, vol. 11, no. 1, p.p. 8492 (2015) 91 6. references [1] mahmoud reza amini and sianemat-nasser “dynamic buckling and recovery of thin cylindrical shape memory shells”. smart structures and materials, 2005, active materials: behavior of mechanics, edited by william d. armstrong. proceedings of spie vol. 5761. [2] z. g. wei, j. l. yu, r.c. batra “dynamic buckling of thin cylindrical shells under axial impact” international journal of impact eng. , 32, (2005), 575-592. [3] m. alexander “an approximate analysis of the collapse thin cylindrical shells under axial loading” quart. j. mech. appl. math. xiii, pt 1.10,1960. [4] abramowicz w. and jones n. , “dynamic progressive buckling of circular and square tubes” , int. j. impact eng., 1986, vol. 4, no. 4, p243-270. [5] gu w, tang w, liu t., “dynamic pulse buckling of cylindrical shell subjected to external impulsive loading”. j. pressure vessel technol, 1996, 118: 33-7. [6] murase k, jones n. , “ the variation of modes in the dynamic axial plastic buckling of circular tubes”. in: gupta nk editor. plasticity and impact mechanics, new delhi: wiley eastern limited, 1993, p222-37. [7] abramowicz w, jones n., “ transition from initial global bending to progressive buckling of tubes loaded statically and dynamically” int. j. impact eng. 1997, 19, p 415-37. [8] karagiozova d., jones n. “on dynamic buckling phenomena in axially loaded elastic – plastic cylindrical shells” int. j. non-linear mech., 2002, 37, 1223-38. [9] w. johnson , “ impact strength of material” , edward , london, 1972. [10] chang hwan kim “development of simplified models for automotive crashworthiness simulation and design using optimization”, ph.d. thesis graduate college the university of iowa city, iowa, 2001 [11] ku j.k. ,seo k.s. , parkland s.w., kim y.j. “ axial crushing behavior of the intermittent tack-welded cylindrical tubes”. international journal of mechanical science,43 ,pp 521-542, 2001. [12] abramowicz w. and jones n. , “ dynamic axial crushing of circular tubes” , int. j. impact eng., 1984, 2, p263. [13] yang, c. c., “dynamic axial crushing of aluminium square tubes”, proceedings of the 18th national conference on mechanical engineering, taiwan, r.o.c., vol. 3, pp1033-1040, 2001. [14] yang, c. c., “dynamic axial crushing of square mild steel tubes”, the 25th conference on theoretical and applied mechanics, taiwan, r.o.c., pp2697-2713, 2001. [15] ayad a.k. “low speed impact of thin walled circular tubes”, m.sc. thesis , alanbar university , 2001. �� 1، ا���د�11ا���ارز� ا������� ا������� � ھ�� ��� ا��� � ،2015( 8492( 92 ا���ن ����ن "#� ck45درا�� ���� و�'#�� ������ ا& %�ام ا� **أ,+م *� ا&��# *ھ�� ��� أ��� � ھ���� ا���ا� *�� )'�اد ا�&%#� ا�$��#�/ " وا� �د � ھ���� **�� ا�0+, � ا�$&����/#� /ا�&.-و,#&+*#( haniazizameen@yahoo.com :ا�4-�3 ا�2&$-و*1 ahlmabdalamir@yahoo.com :ا�4-�3 ا�2&$-و*1 ا��+ � � 1c ھbا ا�a4@ درا�� ?<+دم )�->� ,�;:�9 2*+)#" ر�#�� ا��0ران ا��ا7-�3 ,6 , �ن ?ck45 . هbر ا�$0+>#� ?�ر03#+ و? -ف ھ�f? درا�� �? ��و � ا/-اء ا��را�+ت ا� n%#� وا��o j%< �3-i+�� ا2*4 +ج ا�%�ن ا�n$��م *$#�0 ? -ض ا2*�4ب ا��ا7-ي ا�j . ا�i+ھ-ة )��3+,#&#� ?��م ا2*4 +جr ،@a4ا ا�b1 ھc � و)�+ء /.+ز ��را�� �%�ك #n>? لwx 6, ري�a, دم+>? ynock45 za? �9:;�, �,�[ �<-� -#r\?m/s )3.8 j6.25ا� .( �� واno2+ل ا�za? �#`-a �-ع ,;$%:�) *�nذج )-ا,�`_(3$\�^ ا� yn ,6 ا�0[ء ا� n%1 وا�0[ء ا��i-ي +fازد3+د �->� ا�$<+دم، . 2,$<+ص ا� ��< � ا�$�gه ا�n-ون يأ93+ 2*.#+ر ذ .��ف ?[داد cck45+ن �#�n ا/.+د ا��ea ا���3+,#&#� �ـr ،ه ,-ن�g? لwx 6, �31 ا��4اc -n3 �4ب*hان ا @#o ا�%�ن 3�$n)+�[3+دة. �a3ث ?�gه ا�%�ن، و) � ذ�( c+ن ا2*�4ب �a3ث )i ا2*.#+ر ا�%�ن i3�g$ن ا�+c ،y�? ان ا���ة @#o . -.ا���3+,#&1 اظ -#r\$� _`�,ذج )-ا�n* �(+f$?+ 1c 1ا��o وت+:? l, �#/ y&g( m7+$1 ا�0[ء وا93. ٪٤٥ا��c yna1 ا�c ز3+دة jدي إ�r3 �#`-aا� ��+fأو ا� �<-�+ n3&6 اst+رة إ�j أن ز3+دة 1c ا� �� fx#� أ1c �#�c ا�0[ء ا��i-يw 6 ?�4و ا�#o 1c 1%n ا�. <4d6963726f736f667420576f7264202d20cdd3ede420dae1dfc7e6ed20e6c7c8cae5c7e120e6e3c7e3e6e43134372d20313533> al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 14, no.2, june, (2018) p.p. 147 153 studying the effect of different wt % al2o3 nanoparticles of 2024al alloy / al2o3 composites on mechanical properties al-alkawi hussain jasim mohammed* abthal abd alrasiaq** mamoon a. a. aljaafari*** *department of electromechanical engineering / university of technology /baghdad **department of mechanical engineering / university of technology /baghdad *** department of mechanical engineering / university of al-mustansiriya / baghdad *email: alalkawi2012@yahoo.com ibtihalnamie@yahoo.com **email: (received 20 october 2016; accepted 13 june 2017) https://doi.org/10.22153/kej.2018.06.004 abstract the nanocompsite of alumina (al2o3) produced a number of beneficial effects in alloys. there is increasing in resistance of materials to surface related failures , such as the mechanical properties , fatigue and stress corrosion cracking .the experimental results observed that the adding of reinforced nanomaterials type al2o3 enhanced the hb hardness, uts, 0.2 ys and ductility of 2014 al/al2o3 nano composites . the analysis of experiments, indicated that the maximum enhancement was observed at 0.4 wt.% al2o3. the ultimate improvement percentage were 15.78% hb hardness, 18.1% (uts), 12.86% (0.2 ys) and 25.71% ductility. these enhancements in the above properties maybe to high dislocation density resulting in good bounding between al2o3 and metal matrix. keywords :2024 al.alloy , 2024/ al2o3 nanocomposites, al2o3,mechanical properties, metal matrix . 1. introduction most engineering components which operates in the fields of aerospace, automotive and marine applications need to improve their mechanical properties like tensile strength, yield strength, hardness and strength to weight ratio. a composite is a material which consists of two or more combined elements. one is referred as matrix and the other is called reinforcing element. the reinforcing material may be in the form of fibers or flakes. the composites are divided into main branches depending on the chemical analysis of matrix element [1]. 1. metal matrix composites (mmc�). 2. polymer matrix composites. 3. ceramic matrix composites. different reinforcement materials such as si�n� , b�c, sic and al2o3 used to improve the mechanical properties of the composites. a comprehensive review was done on the mechanical properties i-e strength to weight ratio and tribological properties [1]. m. vykuntarao et al [2] studied the influence of various reinforced particles on the mechanical properties of aluminium based metal matrix composite using stir casting method and they found that increasing wt% of nanomaterial leading to improving the mechanical properties of composites. also the finer size of reinforced particles the height composite mechanical properties. lakhvir singh et al [3] fabricated (mmc�) with three different wt% of al2o3 particles reinforced in pure aluminium i-e 3,6,9 wt%. they found that the mechanical properties increased with increased the weight percentage (wt%). sajjadi et al [4] used two different sizes of reinforcement 20 µm (micro) and 50 nm (nano) of al2o3 with aluminium alloy as matrix. it was al-alkawi hussain jasim al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 147153 (2018) 148 observed that the compressive strength, and hardness of (mmn�) increased when the wt% of al2o3 increased. also the compressive stresses in nanocomposite were higher than those in micro composites. mazahery et al [5] tested al (a356 alloy) / nano al2o3 composites fabricated by stir casting technique using different volume fraction of nanomaterial. the experimental results revealed that the significant raising in hardness, ultimate tensile strength while the ductility was reduced. this improvement is resulted due to uniform distribution of reinforced material and refinement of aluminium matrix grains. baradeswaran et al [6] examined 7075 al alloy/ al2o3 composites manufactured by liquid metallurgy method. they observed experimentally that the ultimate strength (tensile and compressive), and hardness increased in a linear manner with increasing the al2o3 wt%. al-alkawi et al [7] tested a nanocomposites containing ,0.3%, o.5% and 0.7% wt.of al2o3 reinforced material using stir casting method. they found that 0.3% wt. exhibited best mechanical properties of nanocomposites. alumina is a suitable choice as reinforcement due to its good mechanical properties and thermodynamic stability with aluminum. aluminum /al2o3 composite 10% wt. of 2014 with (20 -50 ) μm particle size . the expermantal analysis indicated that the composite exhibited higher mechanical properties such as yield and ultimate stress [8]. 2. experimental details the below tables describe the metal matrix with its physical and chemical properties and the nanomaterial reinforcement, the metal matrix nano composites(mmncs) preparation and testing the metal matrix the metal matrix used in this study was 2024/al alloy. the chemical composition in wt. % is given in table (1) table 1, chemical composition wt. % of 2024/al alloy. note: the standard values represent maximum if range not shown, al is balance wt. %. the 2024/al alloy plates are used in fuselage structure, wing tension members, shear webs and ribs while sheets are usually used in commercial and military aircraft for fuselage skins, wing skins ad engine areas where elevated temperatures to 2500f (1210c) are often encounted [ 9] . the mechanical properties of 2024-zero temper sheet and plates are given in table (2) mechanical properties of 2024-zero temper [9]. table 2, mechanical properties of 2024-0 temper 3. the reinforcement material the reinforced material was al2o3 with particles mean size of about (10) nm table (3) shows the chemical composition of al2o3 in wt. % [ 10 ]. table 3, chemical composition of al2o3 wt% the mechanical and microstructural properties via volume % of nano alumina (al2o3) particles were examined by mohsen and mazahery [10] and tableted below in table (4): si wt. % fe wt. % cu wt. % mn wt. % mg wt. % cr wt. % zn wt. % ti wt. % others total wt. % 2024al alloy standard ref [11] 0.50 0.50 3.8-4.9 0.3-0.9 1.2-1.8 0.1 0.25 0.15 0.15 2024al-alloy experimental 0.48 0.46 4.2 0.52 1.48 0.08 0.21 0.11 - thickness tensile strength yield strength elongation % 0.01-4.99 in 32(max.) ksi 14(max.) ksi 12 0.25-12.44 mm 220 mpa 96 mpa 12 element tio2 cao fe2o3 alumina (α) others wt.% 1.8 1.1 0.8 97 0.02 al-alkawi hussain jasim al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 147153 (2018) 149 table 4, mechanical and microstructural properties of al2o3 vol.% bharath et al [ 13 ] tested the physical and mechanical properties of the reinforcement particles and found that density (gm/cm3)=3.69 ,hardness (hb500)=1175 , strength (mpa)= 2100c( compression) and modules of elasticity (gpa)= 300. it is clear that the presence of al2o3 reinforced material in the composite lead to improve the mechanical properties because the al2o3 particles itself relatively have high mechanical characterization as mentioned above 4. preperation of composite the alumina particles of about (10 nm) size were selected as a reinforced material due to the reasons [ 13 ] : 1-it has good thermal stability. 2-good wear resistance and high surface hardness. 3-low in cost and available. the mmcs reinforced with weight percentage (0.2 , 0.4 , 0.6 , 0.8 and 1.0) % of alumina have been fabricated using the stir casting technique. before introducing the al2o3 particles into the melt, the particales were preheated to a temperature of 2000c and the stirrer was preheated before immersing into the melt, and running at speed of 450 rpm. the casting temperature of 8500c was adopted and the molten composite was poured into the cast iron moulds .thus composite with 0.2 , 0.4 , 0.6 , 0.8 and 1.0 wt. % of al2o3 were produced in the form of rods. the above melting for manfucacting the mmcs were mentioned in details in ref [14] for the same authors using the manifesting test device for fabricating the mmcs composites. 5. experimental results analysis and discussions hardness test test conditions type of test: hb (brinell hardness testing) applied force: hb 31.25 kgf ball diameter: 2.5 mm. laboratory environmental conditions test temperature: 25 °c. moisture: 40%. test was done under the scope of astm e10 (2012) / iso 6506 (2005) / isiri 7809-1 (83). applied force time: 10 – 15 sec. sample name: cast al 2024, nano composite al 2024 / al2o3 – 0.2%, 0.4%, 0.6%, 0.8% and 1.0%. the test results of hb hardness are given in table (5) and plotted in fig. (1) table 5, brinell hardness tests (hb) results. al2o3 vol .% porosity vol % grain size (nm) elongation % unreinforced 0.47 44 3.0 0.75 0.77 35 1.9 1.5 1.1 31 1.78 2.5 1.4 27 1.9 3.5 1.75 25 1.8 5.0 2.3 24 1.75 material location value 1 (hb) value 2 (hb) value 3 (hb) average value (hb) cast al2024 centre 57 57 56 56.6 al / al2o3 0.2% centre 64 63 64 63.6 al / al2o3 0.4% centre 66 65 66 65.6 al / al2o3 0.6% centre 63 62 63 62.6 al / al2o3 0.8% centre 60 61 61 60.6 al / al2o3 1.0% centre 61 59 61 60.3 al-alkawi hussain jasim al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 147153 (2018) 150 fig. 1. hb average hardness against al2o3 wt.%. it is clear, form the figure (1) above, that the hb hardness increases when the wt.% of nanomaterial increases, the maximum increase of 15.9% is occurred at 0.4 wt.% al2o3 compared to as cast. the results are in good agreement with the findings of dinesh et al [11] who found that an increase of nearly 92% in hardness of al. matrix – al2o3 in comparison with pure aluminium. sajjadi et al [4] studied the hardness of aluminium matrix composites (amcs) reinforced by al2o3 the composites was chosen as: 3%, 5% and 7% (mass fraction). using stirring casting method and they concluded that the increasing of adding al2o3 resulting in increase of hardness of composites. m. karbalaei a. et al [12] used a356 al. alloy as matrix of nano composites reinforced by al2o3 using stir casting technique. they observed that the best hardness was obtained at 240 second of stirring time. but increasing the time of stirring leading to reduction in tensile properties of composite. it is observed from figure ( 1 ), the maximum value of hb was found at 0.4% weight percentage of al2o3, but all the values of al / composites are higher than that of as cast. the main reasons of this improvement may be the followings: 1. the high hardness of al2o3 itself could be attributed to increase the hardness of composite. bharath et al [13] measured the hb (type 500) hardness of al2o3 and recorded it to be 1175. 2. the less porosity and the homogeneous distribution of nanomaterial lead to high value of hardness. tsakiris et al [16] used high power milling method, they found that the optimum milling time leads to uniform distribution of al2o3 particles and reduce the amount of porosity resulting in raising the hardness. tensile uts and yield y.s (0.2% offset) strength test conditions temperature: 25 °c. moisture: 40% reference standard astm b557 the tensile results obtained experimentally are tabulated in table (6) while are plotted in fig. 2. table 6, tensile (uts) and yield (y.s 0.2% offset) strengths material specimen no. specimen diameter (mm) initial area (���) gargle length (mm) uts (mpa) y.s 0.2% offset (mpa) elongation % al2o3 wt.% cast al 1 6.04 28.65 30 177.9 83 10.5 0 al/al2o3 (����) 2 6.07 28.93 30 184.6 89 9.3 0.2 al/al2o3 (����) 3 6.05 28.74 30 210.1 101 7.8 0.4 al/al2o3 (����) 4 6.08 29.03 30 184.4 89 9.4 0.6 al/al2o3 (����) 5 6.09 29.12 30 182.6 85 9.6 0.8 al/al2o3 (����) 6 6.01 28.36 30 180.7 84 9.8 1.0 0.0wt% 0.2wt% 0.4wt% 0.6wt% 0.8wt% 1.0wt% h.b 56.6 63.6 65.6 62.6 60.6 60.3 52 54 56 58 60 62 64 66 68 h b h a rd n e s s al-alkawi hussain jasim al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 147153 (2018) 151 the result of table (6) can be plotted as showing in figure (2). fig. 2. uts and yeild stress against wt. % nanoparticles (al2o3) tensile strength and yield stress (0.2 offset) aluminium matrix composites are widely employed for high performance applications. in order to get good mechanical properties the die and squeeze pressure in the casting method is required [4]. figure (2) shows the variation of uts (ultimate tensile strength) and 0.2 y.s (yield stress) with the reinforcement material al2o3 wt. %. it is clear that, the increasing wt% of al2o3 resulting in increase in the uts and ys. but the maximum increasing values were occurred at 0.4 wt. % al2o3 for both uts and y.s i-e 18.1% and 21.68% respectively. the improvements in the above properties may be due to the reasons: 1. the high dislocation density, the high mechanical properties. the high dislocation density is coming from good bounding between the reinforced material and metal matrix [13]. 2. the less porosity during fabricating the composite resulting in raising the above mechanical properties [15]. ductility fig [3] shows the variation of ductility vs various wt% of al2o3. it is clear that the ductility of 2024 al2o3 decrease with increasing the alumina wt%. all the values of ductility of composite are less than that of as cast al alloy. the maximam reduction was occoured at 0.4 wt% of reinforced material of 25.71%. but mazahery et al [5] examined the ductility of 356 al/al2o3 nano composites fabricated by stir casting method and they found that the maximum improvement was happened at 2.5 al2o3 vol% casted at 800c. fig. 3. the elongation vs. with various al2o3 wt. %. 6. conclusions the experimental results revealed the following remarks obtained from this study. 1. all the mechanical properties (hardness, u.t.s and 0.2y.s) were found to be higher than the as cast 2024 al alloy. 2. the maximum improvements in the mechanical properties (hardness, u.t.s, 0.2y.s and ductility) of 2024al /al2o3 wt. % was occurred at 0.4 wt. %al2o3 . 3. the maximum increase in brinell hardness was observed to be 15.78%. 0.0 wt% 0.2 wt% 0.4wt% 0.6wt% 0.8wt% 1.0wt% uts (mpa) 177.9 184.6 210.1 184.4 182.6 180.7 yeild stress (mpa) 83 89 101 89 85 84 0 50 100 150 200 250 al-alkawi hussain jasim al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 147153 (2018) 152 4. the best improvements values of u.t.s was 18.1% and of 0.2y.s was 21.68%. 5. the best improvement of ductility was found at 0.4 wt. % of al2o3.the ductility was reduced from 10.5% as cast to 7.8% at 0.4wt. % al2o3. 7. reference [1] himanhu kala, k.k. s mer, san deep kumar, “a review on mechanical and tribological behaviors of stir cast aluminum matrix composites”, procedia materials science, 6, 1951-1960, (2014). [2] m. vykuntarao, s. chiramjeeva rao, ch. vinod babu, m. v. sekhhar babu, “influence of reinforced particles on the mechanical properties of aluminium based metal matrix composite”. a review chemical science review and letters, 4(13), 335-341, (2015). [3] lakhvir singh, baljinder ram, aman deep singh, “optimization process parameter for stir casted aluminium matrix composite using taquchi”, vol. 02, issue 08, (2013). [4] s. a. sajjadi, h. r. ezatpour, h. beygi, “microstructure and mechanical properties of al-al2o3 mico and nano composites fabrication by strir casting”, materials and science and engineering, a528, 8765-8771, (2011). [5] a. mazahary, h. abdizadeh, h. r. baharvandi, “hardness and tensile strength en a356 alloy matrix / nano al2o3 particle composite”, material and design, to be published, (2015). [6] a. baradeswaran, a. elaya p. , “study on mechanical and wear properties of al 7075 / al2o3 / graphite hybrid composite”, composites part b56, 646-471, (2014). [7] al alkawi h.j.m.,shereen f.a., haneenf.a."an expermantal investigation for some mechanical properties of aluminium – matrix composites renforced by al2o3 nano particle " j., (2015). [8] r.senthilkumar,n.arunkumar , m.manzoor hussain "a comparative study on low cycles fatigue behaviour of nano and micro al2o3 reinforced aa2014 partcales hybrid composites " results in physics, 5 , 273-280, (2015). [9] alcoa green letter no. 188, avoiding stress corrosion cracking in high strength aluminum alloys. [10] mohsen o.s., ali mazhery “aluminumematrix nano composites swarm-intelligence optimization of the microstructure and mechanechal properties” materials and technology 46, 6, 613 (2012). [11] dinesh k., greeta a., rajesh r., “properties and characterization of al-al2o3 composites produced by casting and powder metallurgy routes”, (review), international journal of lattest trends in eng. and technology (ijltet), vol. 2, issue 4, (2013). [12] m. karbalaei akberi, o. mrrzaee, h. r. bahasvand, “fabrication and study on mechanical properties and fracture behaviour of nanometric al2o3 particle – reinforced of a356 composites focusing on the parameters of vortex method”, material and design, 46, 199-205, (2013). [13] bharath v., mahadev n., v. auradi, “preparation characterization and mechanical properties of al2o3 reinforced 6061 al. particulate mmcs”, international journal of eng. research and technology, vol. 1, issue 6, (2012). [14] al-alkawi h.j.m, abthal a. al rasiaq , mamoon a.a. al jaafari “performance study on mechanichal properties in 7075 aluminam alloy and al2o3 nano composites” j. of eng. and technology, to be published (2016). [15] j. hashim l. looney, m. s. j. hashmi, journal of materials processing technology, 92-93, (1-7), (1999). [16] v.tsakiris, w. kappel, eenescu, g. alecu, f. albu, f.grigore, v. marinescu, m. lungu " characterization of al. matrix composites reinforced with alumina nanoparticles obtained by pm method " journal of optoelectronics and advanced materials, vol.13, no.9, pp.1172-1175, 2011. )2018( 147-153، صفحة2د، العد14دجلة الخوارزمي الهندسية المجلم حسين جاسم محمد العلكاوي 153 دراسة تاثير النسب الوزنية المختلفة للمادة النانوية في المركبات النانوية على المواصفات الميكانيكية ***مأمون علي الجعفري **ابتهال عبد الرزاق *حسين جاسم محمد العلكاوي الكهروميكانيكية/ الجامعة التكنولوجية*قسم الهندسة **قسم الهندسة الميكانيكية/ الجامعة التكنولوجية ***قسم الهندسة الميكانيكية/ الجامعة المستنصرية yahoo.com2012alalkawi@*البريد االلكتروني: ibtihalnamie@yahoo.com**البريد االلكتروني: لخالصة ا هذه في زيادة مقاومة المواد على السطح التأثيرات، اعطى عدد من التاثيرات االيجابية في السبائك، 3o2alالمواد المركبة النانوية بواسطة االلومنيا التاكل االجهادي. اوظحت النتائج العملية ان اضافة المادة المقواة نوع تحسن الكالل والتشقق نتيجة ،المتعلقة بالفشل مثال على ذلك المواصفات الميكانيكية تحسن تمت مالحظته عند أعظم. التحليالت اوضحت ان 3o2al/ al2024الى والمطيلية %٠٫٢اجهاد الخضوع عند األعظم،اجهاد الشد ،صالدة برينل الخضوع و إلجهاد %٢١٫٨٦ األعظم،الجهاد الشد %١٨٫١ ،صالدة برينيلل %١٥٫٨٧نسبة وزنية الى االلومينا. حيث كان اعظم تحسن %٠٫٤ .األساسللمطيلية. هذا التحسن في المواصفات اعاله نتيجة الى الكثافة العالية لالنخالعات مؤدية الى تماسك جيد بين االلومينا والمعدن %٢٥٫٧١ al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 2030 (2015) influence of coating with some natural based materials on the erosion wear behavior of glass fiber reinforced epoxy resin aseel basim abdul hussein* emad saadi al-hassani** reem alaa mohamed*** *,**,***department of materials engineering / university of technology **email: dr.material@yahoo.com **email: emad2000x@yahoo.com ***email: ra_aljubory@yahoo.come (received 13 july 2014; accepted 25 january 2015) abstract in the present study, composites were prepared by hand lay-up molding. the composites constituents were epoxy resin as a matrix, 6% volume fractions of glass fibers (g.f) as reinforcement and 3%, 6% volume fractions of preparation natural material (rice husk ash, carrot powder, and sawdust) as filler. studied the erosion wear behavior and coating by natural wastes (rice husk ash) with epoxy resin after erosion. the results showed the non – reinforced epoxy have lower resistance erosion than natural based material composites and the specimen (epoxy+6%glass fiber+6%rha) has higher resistance erosion than composites reinforced with carrot powder and sawdust at 30cm , angle 60°, grin size of sand 425µm , temperature 30ċ , 300 gm salt content in 2liter of water and 15 hour. coating specimen with mixed epoxy resin -rha with particles size in the range (1.4-4.2) µm improves erosion wear resistance characteristics of the coated specimen, coating thickness was (16 ± 1) μm and after erosion at (15 hour) the thickness was (10) μm . keywords: composites, preparation of natural materials, erosion wear, glass fiber, coating. 1. introduction epoxy resin is widely used in a variety of technical applications such as adhesives, protective coatings, sealants, and matrices for composite materials in aerospace and leisure industries [1]. this wide range of applications arises from characteristics of epoxy resins including high chemical and corrosion resistance, good mechanical and thermal properties, adhesion to various substrates, low shrinkage upon cure, flexibility, good electrical properties, and easy processability [1, 2]. however, despite these advantages, there are also some drawbacks: high water uptake, moisture absorption and brittle nature owing to their highly cross-linked structures, low wear resistance and high friction coefficient. many of our technologies require materials with unusual combinations of properties that cannot be met by the conventional metal alloy, ceramics and polymeric materials. a composite is a multiphase material that is artificially made and chemically dissimilar and separated by distinct interface. one of these phases is termed the matrix which is continuous and surrounds the other phase often called the reinforcement phase which consists of three main divisions: particles, fibers and structure, which should be much stiffer and stronger than the matrix. polymeric composite is considered the earliest type of composite that is used in the greatest diversity of composite applications as well as in the largest quantities in the light of mailto:dr.material@yahoo.com mailto:emad2000x@yahoo.com mailto:ra_aljubory@yahoo.come aseel basim abdul hussein al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 2030 (2015) 21 suitable ambient temperature properties, ease of fabrication, low density, good ductility and low cost. polymeric materials could be classified according to behavior with rising temperature in to (thermosets, thermoplastics) [3, 4, and 5]. fiber –reinforced polymer (frp) composites are widely used in design due to relatively lowdensity and reliable tailoring capability to provide the required strength and stiffness. numerous possible capabilities and low noise make the (frp) composites as better substitute over conventional metallic materials for tribological application. the different application areas are gears, cams, wheels, impellers, brakes, artificial prosthetic joints, seals, bushes, bearings, ect…. [6]. solid particle erosion is one type of wear that causes. local damage combined with the progressive loss of original material from a solid surface due to micro mechanical interaction between that surface and solid particles. it has been reported that the surfaces of (frp) equipments operating in erosion environments were impacted by the solid particles contained in the air or water, which destroy the materials. it was widely recognized that polymers and their composites had poorer erosion resistance than metals, and that polymer composites containing reinforcement fiber (frp) usually erode faster than neat polymers. in other words, the reinforcement fiber could enhance the strength of polymer composites, but reduced the erosion resistance of the polymer composites in generally. in order to reveal the facts about erosion wear of polymer matrix composites, this study investigated some of the physical and mechanical properties of composites materials fiber reinforced polymer; then investigating the erosion behavior of these composites. it was feasible to prepare composites with high strength, low density and excellent erosion resistance by composites structure [7]. there are many studies about erosion wear behavior of composite material aireddy h. and mishra s.c. (2011) have studied the effects of impact velocity and erodent particle size on the solid particle erosive behavior of coir dust reinforced polymer composites. the erodent used here is silica sand having the size range 200600 μm. however it was found that the erosion wear rate was decreased with increasing the coir dust amount because at higher amount of coir dust the mechanism dominated by the fiber material which is soft compare with the matrix material . decrement of erosion wear has been observed with increasing erodent particle size , the highest erosion wear rate at 90° impingement angle [8]. mohammed ismail et. al., (2012) have studied the carbon fabric reinforced epoxy (c-e) composites filled with different weight proportions of fly ash cenosphere (csp) were fabricated by hand layup technique followed by compression molding. the solid particle erosion characteristics of the (csp) filled (c-e) composites have been studied and the experimental results are compared with those of unfilled (c-e) composites. for this, an air jet type erosion test rig and taguchi orthogonal arrays have been used. the findings of the experiments indicate that the rate of erosion by impact of solid erodent has been greatly influenced by various control factors. the tensile modulus and flexural modulus of cenospheres filled (c-e) composites showed good improvement compared with that of the unfilled (c-e) composites. low density 0.6 g/cm 3 and higher silica content 60% of cenospheres seems to be the reason for this observation. the comparative study indicates that the (csp) filled (c-e) composites exhibit better erosive wear performance than that of the unfilled (c-e) composites. the (csp) filled and unfilled (c-e) composites showed ductile erosion behavior, with maximum erosion at 30° impingement angle. overall the erosion rate was found to increase with impact velocity. furthermore, the filler content is the powerful influencing factor followed by impact velocity, impingement angle, erodent size and erosion time during the erosive wear process [9]. kouloumbi n . et. al.,( 1996) have studied the steel specimens were coated by a spinning process with particulate polymeric composites consisting of an epoxy resin (dow 33 1) and iron powder. applied coatings were roughly 70 pm thick and the contained quantity of iron particles was varied 7.5, 15, 30% wt. the effect of the presence of iron particles in the coatings as well as the influence of their concentration on the evaluation of the coatings’ behavior in a corrosive environment 3.5% nacl . electrochemical impedance spectroscopy, corrosion potential, corrosion current density (tafel) and dielectric measurements were performed. minor differences in the anticorrosive behavior of the coatings were observed irrespective of the iron content in the coating. effective resistance inhibition action of the composite coatings has been diminished with the increase of exposure time to the corrosive environment being in all cases very close to that of the pure epoxy resin coatings [10]. amar patnaik et. al., (2010) have studied the fiber reinforced polymer composites often have to function in severe erosive environment in which they encounter solid particle erosion. in hybrid aseel basim abdul hussein al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 2030 (2015) 22 composites consisting of reinforcing fibers and particulate filled polymer matrices, the filler material plays a major role in determining the magnitude and mechanism of damage due to erosion. study of the influence of three different particulate fillers namely fly ash, alumina (al2o3) and silicon carbide (sic) on the erosion characteristics of glass polyester composites. for this purpose, an air jet type erosion test configuration and the design of experiments approach utilizing taguchi‘s orthogonal arrays are used. the wear rates are found to be in good agreement with the theoretical values obtained from an existing prediction model. this study reveals that addition of hard particulate fillers like flyash,(al2o3) and (sic) improves the erosion resistance of glass polyester composites significantly [11]. bagci et m. al., (2011) have studied the materials added to the matrix help improving operating properties of a composite. this experimental study has targeted to investigate this aim where (silicon oxide) particles have been added to glass fibre and epoxy resin at an amount of 15% to the main material to obtain a sort of new composite material. erosive wear behavior of epoxy-resin dipped composite materials reinforced with glass fibre and (silicon oxide) under three different impingement angles 30°, 60° and 90°, three different impact velocities 23, 34 and 53 m/s, two different angular aluminum abrasive particle sizes approximately 200 and 400 μm and the fiber orientation of 45° (45/-45) have been investigated. in the test results, erosion rates are obtained as functions of impingement angles, impact velocities, particle sizes and fiber orientation. moreover, materials with addition of (silicon oxide) filler material exhibited lower wear as compared to neat materials with no added filler material. the results show the wear of (gf/ep) (neat) test specimens is higher than that of (gf/ep) (silicon oxide) test specimens. that is; the added (silicon oxide) particles impose positive effects on erosive wear and thus decreasing the erosion rates, all composites regardless of their different features exhibit maximum erosion rates at 30° impingement angle and thus exhibiting similar behavior as that observed for ductile materials, large abrasive particles lead to an increase in wear. a marked increase in erosion rate was observed as the abrasive particle size increased from 200 to 400µm ,test specimens with (45/-45) fiber orientation are more wear resistant than their counter parts with 0/90 fiber orientation [12]. 2. erosion wear erosion wear, which arises from solid particle impacting, is one of the major failure modes that cause offshore structure damage. erosion is found in a wide range of equipments in offshore industry, in which solid particles are entrained into fluid flow in the operating process, such as gas turbine, oil & gas pipeline, drilling platforms, etc [13]. this damage mode affects not only operating process, but also safety and economics as well. therefore, it is necessary to find a good predictive method to accurately predict the erosion rate for offshore equipment. the erosion mechanism is different in ductile and brittle materials as shows in fig. (1). a number of studies have been performed to reveal the erosion mechanisms of ductile and brittle materials [14, 15]. it is now known that brittle materials erode by cracking and chipping, while ductile materials erode by a sequence of micro-cutting, forging and fracture, etc [16]. hence, erosion rate and mechanism are highly dependent on material types. erosion rate of the volume loss (v) is defined by the following equation [7] where ε: erosion rate of weight loss. wl: weight loss of the specimen (gm). ws: total weight (gm). ρ: density of the tested material (g/cm 3 ) . fig. 1. behavior of brittle and ductile material. aseel basim abdul hussein al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 2030 (2015) 23 3. experimental work (preparation of natural materials) acarrot powder carrot seeds were purchased locally from vegetable supplier. they were cleaned to remove all foreign matter such as dust, dirt, and stones. the juice was removed from carrot seeds the solid waste from carrot juice is rich in fiber which regarded as a functional fiber source. the waste was dried to a constant weight and then grounded by using a grinder and sieved. two sizes were obtained, once (fine fiber) is less than 50 µm and the other (coarse fiber) is between 100-150 µm which represent as accumulated fibers [17]. brice husk ash rice-husk is an agricultural by-product material. it constitutes about 20% of the weight of rice. it contains about 50% cellulose, 25–30% lignin, and 15–20% of silica. when rice-husk is burnt rice-husk ash (rha) is generated. on burning, cellulose and lignin are removed leaving behind silica ash. the controlled temperature and environment of burning yields better quality of rice-husk ash as its particle size and specific surface area are dependent on burning condition [18, 19]. to produce the best pozzolanas, the burning of the husk must be carefully controlled to keep the temperature below 700°c and to ensure that the creation of carbon is kept to a minimum by supplying an adequate quantity of air. at burning temperatures below 700°c an ash rich in amorphous silica is formed which is highly reactive. temperatures above 700°c produce crystalline silica which is far less reactive. the presence of large quantities of carbon in the ash will adversely affect the strength; the carbon content of the ash should be limited to a maximum of 10%. there are several designs of small simple incinerators, normally made of fired clay bricks, which are capable of burning ash at temperatures below 700°c and without excessive quantities of carbon [20]. the second step in processing is milling the rha to a fine powder, and ball or hammer mills are usually used for this purpose. crystalline ash is harder and will require more milling in order to achieve the desired fineness [21]. suitability of rha mainly depends on the chemical composition of ash, predominantly silica content in it. rha is found to be superior to other supplementary materials like slag, silica fume and fly ash [22, 23]. csawdust (wood powder) sawdust is a by-product of cutting, grinding, drilling, sanding, or otherwise pulverizing wood with a saw or other tool; it is composed of fine particles of sawdust. it is also the byproduct of certain animals, birds and insects which live in wood, such as the woodpecker and carpenter ant. it can present a hazard in manufacturing industries, especially in terms of its flammability. sawdust is the main component of particleboard [24]. 4. specimen preparation the basic materials used in the preparation of research specimen consisting epoxy resin quickmast (105) base as the matrix with a density of (1.2 gm / cm 3 ) with (6%) volume fraction of glass fibers (woven eglass fiber) and 3% , 6% volume fraction of natural powder (rha ,carrot powder ,sawdust) . all the required moulds for preparing the specimens were made from glass with dimensions of (150×150×5) mm. the inner face of the mould was covered with a layer of nylon (thermal paper) made from polyvinyl alcohol (pva) so as to ensure no-adhesion of the resin with the mould. the method used in the preparation of the specimen in this research is the (hand lay –up) molding. 5. erosion wear test this test is performed according to (astm g76) at room temperature [25, 26]. samples have been cut into a diameter of (40mm) and a thickness of (5mm). fig. (2) shows standard specimens for erosion wear [27]. http://www.ask.com/wiki/wood?qsrc=3044 http://www.ask.com/wiki/saw?qsrc=3044 http://www.ask.com/wiki/woodpecker?qsrc=3044 http://www.ask.com/wiki/carpenter_ant?qsrc=3044 http://www.ask.com/wiki/particleboard?qsrc=3044 aseel basim abdul hussein al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 2030 (2015) 24 (a) fig . 2. a.b. standard specimens. the used device for erosion is locally manufactured the principal scheme is shown fig. (3). the perspex tank is used as a chamber has dimensions of (40) cm in length, (20) cm in height, and (20) cm in width. the pump joints and valves connected to the chamber are made from steel and slurry as well as jet nozzle. the distance between the nozzle and the sample tube are (20, 25, 30) cm, pump diameter is (40) mm and the nozzle diameter (5mm). erosion tests are performed by changing the angle between the fluid flow and the horizontal axis of the test specimen (α), at three levels (90°, 60°, 30°). it is operating flow rate (35 l∕min). the fluid used in the erosion tests are sand water contains a solid particles of abrasives with different sizes (425, 600,800) μm .in this work, an orthogonal array of the type (l18) has been chosen since there are eight factors (variables) and three levels [28] as shown in fig.4(design of the orthogonal array l18) . during the erosion wear test, eight test factors for each type of composites are considered, these are: (1) test time; (2) reinforcement volume fraction; (3) stand-off distance; (4) angle; (5) grin size ;( 6) temperature; (7) salt content; and (8) water content each at three levels. fig .3. erosion wear device. 40 mm 5 mm (b) epoxy+6%gf+3%rha epoxy+6%gf+6%rha pure epoxy epoxy+6%gf epoxy+6%gf+3% carrot powder epoxy+6%gf+6% carrot powder epoxy+6%gf+ 3%sawdust epoxy+6%gf+ 6% sawdust aseel basim abdul hussein al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 2030 (2015) 25 fig. 4. design of the orthogonal array (l18). 6. coating in this work the spin coating used of coating all the specimens that have been erosion will be specifications (mode 410, origin taiwan), as shown in fig.5. (spin coater device). spin coating is a procedure used to deposit uniform thin films to flat substrates. usually a small amount of coating material is applied on the center of the substrate, which is either spinning at low speed or not spinning at all. the substrate is then rotated at high speed in order to spread the coating material by centrifugal force. a machine used for spin coating is called a spin coater, or simply spinner. rotation is continued while the fluid spins off the edges of the substrate, until the desired thickness of the film is achieved. during spin coating, a polymer solution in a solvent is applied to the center of a flat substrate. the spin coater rotates the substrate at high speed in order to spread the fluid by the centrifugal force. because the solvent is volatile, a thin layer of polymer will be left at the substrate. the thickness and uniformity of such film are greatly affected by the polymer solution and spin speed. the thickness of the film also depends on the viscosity and concentration of the solution and the solvent [29]. fig . 5. spin coater device. 7. spin coating process spin coating has been used for several decades for the application of thin films. a typical process involves depositing a small puddle of a fluid resin onto the center of a substrate and then spinning the substrate at high speed (typically around3000 rpm). centripetal acceleration will cause the resin to spread to, and eventually off, the edge of the substrate leaving a thin film of resin on the surface. final film thickness and other properties will depend on the nature of the resin (viscosity, drying rate, percent solids, surface tension, etc.) and the parameters chosen for the spin process. one of the most important factors in spin coating is repeatability. subtle variations in the parameters that define the spin process can result in drastic variations in the coated film [30]. in this research was the preparation steps for the purpose of coating mixing are the following : 1. weight 10 gm from epoxy. 2. weight 7 gm from hardener. 3. weight 10 gm from rice husk ahs 4. mixing the epoxy with the hardener continuously and slowly by using a glass rod so as to avoid bubbles. the mixing is carried out at room temperature. 5. adding the powder (rice husk ash) intermittently in to the mixture and stirring it for a period of (10-15) minutes to obtain homogeneity. 6. pouring the mixture to the sample (which does not have the resistance of the erosion ware to improve the resistance to wear erosion) is installed in the device (spin coater ) slowly , after proving parameter device which is (time ;3000 sec ,speed ;1000 rpm " revolutions per minute" ;& accelerate ;8 sec ) the spin coater distribute the mixing evenly on the sample. fig.6. shows the specimens after coating by used spin coating. fig .6. some of specimens after coating. aseel basim abdul hussein al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 2030 (2015) 26 8. results and discussion 8.1. erosion wear the results of erosion wear for the pure epoxy and nature based material composites are illustrated in fig .7. particle impingement produces rise in temperature of the surface which makes the matrix deformation easy because the high temperature known to occur in solid particle erosion invariably soften the matrix [31]. on impact the erodent particle kinetic energy is transferred to the composite body that leads to crater formation and subsequently material loss [32]. the results show, the nature based material composites give the lower erosion wear when they are compared with the other (pure epoxy and epoxy +6%glass fiber) composite. the reason is that the presence of reinforcement and filler powder in the matrix helps in absorbing the kinetic energy produced by the impacted erodent particles and therefore making the energy available for the plastic deformation of the matrix to become less [32]. it is clear from fig .7. that addition of powder fillers significantly reduces the rate of material loss. from the fig .7. it is clear that there is a pronounced effect of the addition of 6% glass fiber with 3% and 6% volume frication from (natural powder ) percents on the erosion wear ,it can seen the specimen (epoxy +6% glass fiber +3%,6% rha ) give better erosion resistance than the composites filled with (3% and 6% for carrot powder and sawdust ) at (15 hour) time , (30 cm) stand-off distance, (60 ◦ ) angle, (425μm) grin size of sand ,(30c°) temperature,(300 g) salt content in (2 liter) water content. which may be related to its lower grain size with a good distribution and bonding and since rha is hard, wear-resistant and has high strength and stiffness. thermoplastic matrix composites usually show ductile erosion while the thermosetting ones erode in a brittle manner. thus the erosion wear behavior of polymer composites can be grouped into ductile and brittle categories although this grouping is not definitive because the erosion characteristics equally depend on the experimental conditions as on composition of the target material [32]. in the present study the results show the peak erosion taking place at an impact angle of 30 ◦ and 90 ◦ . this clearly indicates that nature based material composites respond to solid particle erosion not in neither a purely ductile nor a purely brittle manner. this behavior can be termed as semi-ductile in nature. the loss of ductility may be attributed to the incorporation of glass fibers and natural powder both of which are brittle, therefore the used glass fiber and filler (rha) they give the lower erosion wear rate at an impact angle of 30 ◦ . this indicates that bonding in between composite constituents is also an important factor in determining and giving lower erosion. the high erosion wear of (sawdust) in nature based material composites may be related to the poor linkage between matrix material and fillers with the matrix. fig. 7. erosion wear of natural composites materials for 15 hours. 8.2. coating the results of coating and erosion wear after coating for the pure epoxy and natural composites are illustrated in table (1). it is proposed to use the rha with (particle size 1.4-4.2 μm) natural waste in industry as additive to epoxy resin as coating of thermosetting specimen. erosions characteristics of uncoated samples are depicted in fig.(7). the (epoxy+6% glass fiber + 6% rha) experiment showed the best resistance to erosion among the natural-based materials. the (pure epoxy) experiment (10) has been characterized by the following parameters; erosion time of (15 hours), distance of (20 cm), (90°) of impingement angle, (850 μm) grain size, (30 ċ) temperature, (200 gm) salt in (2 liters) of water. the weight of the investigated sample of experiment (10) before coating has been equal to (7.5743 gm), after coating the total weight amounted to (7.9042 gm) which corresponds to a coating thickness of (16 ± 1) μm. after erosion, the sample weight has been found equal to (7.9030gm) with a loss of (0.0012 gm) from the coating layer only. this has been verified under the optical microscope where the coating layer after erosion was measured equal to 10 μm as shown in fig.(8). the (epoxy+6% glass fiber) experiment (13) has been characterized by the following parameters; erosion time of aseel basim abdul hussein al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 2030 (2015) 27 (15 hours), distance of (20 cm), (60°) of impingement angle, (850 μm) grain size, (25 ċ) temperature, (300 gm) salt in (2.5 liters) of water. the weight of the investigated sample of experiment (13) before coating has been equal to (8.3234gm), after coating the total weight amounted to (8.6623 gm). after erosion, the sample weight has been found equal to (8.6614 gm) with a loss of (0.0009 gm) from the coating layer only. the (epoxy+6% glass fiber +3%rha) experiment (17) has been characterized by the following parameters; erosion time of (15 hours), distance of (25 cm), (30°) of impingement angle, (850 μm) grain size, (25 ċ) temperature, (200 gm) salt in (3 liters) of water. the weight of the investigated sample of experiment (17) before coating has been equal to (8.4530 gm), after coating the total weight amounted to (8.7915 gm). after erosion, the sample weight has been found equal to (8.7913 gm) with a loss of (0.0002 gm) from the coating layer only. the weight of the (epoxy+6% glass fiber +6% rha) sample before coating has been equal to (8.7432 gm), after coating the total weight amounted to (9.0725 gm). after erosion, the sample weight has been found equal to (9.0724 gm) with a loss of (0.0001 gm) from the coating layer only. the weight of the (epoxy+6% glass fiber +3% carrot powders) sample before coating has been equal to (8.7630 gm), after coating the total weight amounted to (9.1025 gm). after erosion, the sample weight has been found equal to (9.1020 gm) with a loss of (0.0005 gm) from the coating layer only. the weight of the (epoxy+6%g.f+6% carrot powder) sample before coating has been equal to (9.0170 gm), after coating the total weight amounted to (9.3468 gm). after erosion, the sample weight has been found equal to (9.3464 gm) with a loss of (0.0004 gm) from the coating layer only. the weight of the (epoxy+6% glass fiber +3% sawdust) sample before coating has been equal to (8.2200 gm), after coating the total weight amounted to (8.5589 gm). after erosion, the sample weight has been found equal to (8.5581 gm) with a loss of (0.0008 gm) from the coating layer only. the weight of the (epoxy+6% glass fiber +6% sawdust) sample before coating has been equal to (8.5590 gm), after coating the total weight amounted to (8.8885 gm). after erosion, the sample weight has been found equal to (8.8879 gm) with a loss of (0.0006 gm) from the coating layer only. table 1, coating and erosion wear after coating for the pure epoxy and nature based material composites. composites weight before erosion weight after erosion at 15 hour weight after coating weight after erosion at 15 hour pure epoxy 7.7006 7.5743 7.9042 7.9030 epoxy+6% glass fiber 8.3645 8.3234 8.6623 8.6614 epoxy+6% gf+3%rha 8.4597 8.4530 8.7915 8.7913 epoxy+6% gf+6%rha 8.7495 8.7432 9.0725 9.0724 epoxy+6% gf+3% carrot powder 8.8148 8.7630 9.1025 9.1020 epoxy+6% gf+6% carrot powder 9.0497 9.0170 9.3468 9.3464 epoxy+6% gf+3% sawdust 8.2750 8.2200 8.5589 8.5581 epoxy+6% gf+6% sawdust 8.6127 8.5590 8.8885 8.8879 aseel basim abdul hussein al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 2030 (2015) 28 fig . 8. specimen after coating and erosion wear at 15 hour . 9. conclusions the conclusions drawn from the present work are: the natural composites give the lower erosion wear than (pure epoxy and epoxy +6% glass fiber) composite material. composites with (epoxy +6% glass fiber +6%rha) give better erosion resistance at (30 cm ) stand – off distance , (60°) angle , (425µm) grin size of sand , (30ċ) temperature , (300 gm) salt content in (2liter ) of water and (15hours) time , while the higher erosion wear is for the (epoxy +6% glass fiber+6% sawdust) .the loss of weight of pure epoxy (0.1%) for (epoxy+6%glass fiber) (0.04%) for (epoxy+6%glass fiber+6%rha) (0.006%). results that coating specimens with rha-mixed epoxy resin improve erosion wear resistance characteristics of the coated specimens. 10. reference [1] distasio ji. 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[18] badorul hisham abu bakar, ramadhansyah putrajaya and hamidi abdulaziz ," malaysian rice husk ash – improving the durability and corrosion resistance of concrete: pre-review" concrete research letters,no.1, vol. 1 pp.6-7, march (2010) . [19] keneth kanayo alaneme, idris b. akintunde, peter apata olubambi,tolulope m. adewale " fabrication characteristics and mechanical behavior of rice husk ash – alumina reinforced al‑ mg‑ si alloy matrix hybrid composites", journal of materials research and technology,no.1,vol.2,pp.60-67,(2013) ,(http://dx.doi.org/10.1016/j.jmrt.2013.03.0 11) . [20] nagrale s. d., dr. hemant hajare , pankaj r. modak "utilization of rice husk ash", international journal of engineering research, issue 4, vol. 2, pp.001-005, julyaugust (2012) . [21] godwin a. akeke, maurice e. ephraim, akobo, i.z.s and joseph o. ukpata " structural properties of rice husk ash concrete" international journal of engineering and applied sciences, no. 3, vol. 3, ,pp.57-62, may (2013). [22] muthadhi a and kothandaraman s, "rice husk ash , properties and its uses: a review rice husk ash", ie (i) journal, vol.88, may (2007). [23] sun luyi ,"silicon-based materials from rice husks and their applications", ind. eng. chem. res, vol.40, pp.5861-5877,( 2001) . [24] "wood dust exposure" (http://www.statefundca.com/safety/safetmee ting/safetymeeting article .aspx? articleid=125). state compensation insurance fund. retrieved april 30,( 2012) . [25] anu gupta, ajit kumar, amar patnaik, sandhyarani biswas ," effect of filler content and alkalization on mechanical and erosion wear behavior of cbpd filled bamboo fiber composites", journal of surface engineered materials and advanced technology, no.2 ,pp.149-157 , (2012) , (doi.org/10.4236/jsemat.2012.23024) [26] sandhyarani biswas "erosion wear behaviour of copper slag filled short bamboofiber reinforced epoxy composites ", mechanical engineering department, national institute of technology, rourkela, india ,(2012) . [27] annual book of astm standard, "standard practice for conducting erosion tests by solid particle impingement using gas jet", g 76-83), vol. 03.02, (1988). [28] shyam kumar karna, dr. ran vijay singh, dr. rajeshwar sahai" application of taguchi method in indian industry", issue11, vol. 2,pp.389, november (2012). [29] scriven, le "physics and applications of dip coating and spin coating", mrs proceedings,vol.121, (1988). [30] carcano, g., ceriani, m., and soglio, f. "spin coating with high viscosity photoresist on square substrates" hybrid circuits, vol. 32, p. 12,(1993) . [31] tewari u.s., harsha a.p., häger a.m. & friedrich k.," solid particle erosion of unidirectional carbon fiber reinforced polyetheretherketone composites", wear elsevier, issue 11-12, vol.252 ,pp. 9921000,(2002), (doi:10.1016/s00431648(02)00063-7). [32] patnaik a., satapathy a. & mahapatra s. s., "implementation of taguchi method for tribo-performance of hybrid composites", dep. of mechanical eng. , national institute of technology, rourkela, pp. 779788, (2007). http://dx.doi.org/10.1016/j.jmrt.2013.03.011 http://dx.doi.org/10.1016/j.jmrt.2013.03.011 http://www.statefundca.com/safety/safetmeeting/safetymeeting%20article%20.aspx http://www.statefundca.com/safety/safetmeeting/safetymeeting%20article%20.aspx (2015) 2030، صفحة 2، العذد11دالخوارزمً الهنذسٍة المجلجلة م اسٍل باسم عبذ الحسٍن 30 التً اساسها مواد طبٍعٍة على سلوك بلى التعرٌة لراتنج المتراكبةتأثٍر الطالء لبعض المواد االٌبوكسً المذعم بااللٍاف السجاجٍة ***رٌم عالء محمذ **عماد سعذي الحسنً *اسٍل باسم عبذ الحسٍن لتىىىلىجيت الجامعت ا/ لظم هىذطت المىاد ***،**،* dr.material@yahoo.com : االلىتزووي البزيذ* emad2000x@yahoo.com : االلىتزووي البزيذ ** ra_aljubory@yahoo.come : االلىتزووي البزيذ** لخالصة ا تتىىن المىاد المتزاوبت مه راتىج االيبىوظي مادي اطاص والياف الشجاج . طت طزيمت المىلبت اليذويتاتم في هذا البحث تحضيز المىاد المتزاوبت بىص دراطت .% ( 6، % 3)بىظز حجمي ( بىدرة الخشب وحىق الجشر مض و الزسرماد لشىر ) و مظاحيك طبيعيت محضزة % 6مادة تمىيت بىظز حجمي الىتائج اظهزث بان االيبىوظي غيز الممىي . مع راتىج االيبىوظي بعذ التعزيت ( رماد لشىر الزس)طت الىفاياث الطبيعيت طاالتعزيت والطالء بى بلًطلىن تمله مماومت ( رماد لشىر الزس% 6+ االلياف سجاج %6+ االيبىوظي )اد طبيعت والعيىت التي اطاطها مى يمتله مماومت للتعزيت لليلت مه المىاد المتزاوبت ċ 25ودرجت حزارة ، مايىزون 850، حجم دلائك تعزيت 30ºطم ، ساويت 25عىذالمذعمت بمظحىق الجشر وبىدرة الخشب مه المىاد المتزاوبت للتعزيت مايىزون ( 2.4-1.4)يىاث بزاتىج االيبىوظي مع رماد لشىر الزس مع حجم حبيبي ضمه المذي طالء الع . طاعت 15لتز مه ماء 3غم ملح في 200، ( 10)طاعت اصبح طمه الطالء 15وبعذ التعزيت عىذ مايىزون (1 ± 16) وطمه الطالء وان، لتحظيه خىاص مماومت التعزيت للعيىاث التي تم طالئها . مايىزون mailto:dr.material@yahoo.com*البريد mailto:dr.material@yahoo.com*البريد mailto:emad2000x@yahoo.comالبريد mailto:emad2000x@yahoo.comالبريد mailto:ra_aljubory@yahoo.come**البريد mailto:ra_aljubory@yahoo.come**البريد 28-35 al-khwarizmi engineering journal,vol. 11, no. 4, p.p. 2 design and construction of and the optimum parameters water and alaa dhari jawad al institute of technology-baghdad/ (received 24 march 2015 ; accepted 16 june 2015) abstract electrical magnate was designed and constructed, the optimum magnetic flux and the effect of time on the physical properties of the alkaline (magnetic water) produced from the bottled drinking water [the total dissolved solids (tds) or the electrical conductivity, and ph] were studied, to simulate zamzam water in mekka saudi arabia. also, the efficiency of magnetic field from this nacl content), to convert it to water suitable fo show that the magnetic flux from our designed electrical magnate in the range of (0.013 magnetic treatment time is sufficient to produce alkaline water with p while 60 minutes of magnetic treatment result when the magnetic flux is 0.026 tesla. that , the maximum decrease in tds is took place when the magnetic flux is 0.0 and the time for magnetic treatment is 30 minutes where the tds of 1730 ppm reduced to 1290 ppm effect of magnetic treatment on the ph change of high nacl content water give maximum ph value magnetic flux is 0.013 and 0.028 tesla (the voltages is 1.5 & 3 v respectively and 100 turn coil) and the time period of magnetic treatment is 30 minutes. the trend of results agreed well with treatment lead always to increase of ph, decrease in tds and electrical conductivity keywords: electrical magnate, magnetic water, 1. introduction magnetic water (mw) is the water which passed for a certain period of time through magnetic field [1]. mw is used in industry, agriculture and medical applications , in industry is used to prevent the scales from the inner tubes and in agriculture it is used to increase the flowering of the fruits [2]. in medical applications, mw can be used to dissolve the stones in kidney and dissociating the salts of solid mass, it is also used to decrease the cholesterol and salts from arteries, decreasing t of pumping the blood by the heart. in the broken bones the mw will increase the immigration of the calcium ions to the broken bones and khwarizmi engineering journal,vol. 11, no. 4, p.p. 2835 (2015) construction of electrical magnate to study optimum parameters to produce alkaline magnetic and treating the sea water to be suitabl for irrigation alaa dhari jawad al-bayati baghdad/ middle technical university / foundation of technical education email: bayati.engineer@gmail.com (received 24 march 2015 ; accepted 16 june 2015) electrical magnate was designed and constructed, the optimum magnetic flux and the effect of time on the physical properties of the alkaline (magnetic water) produced from the bottled drinking water [the total dissolved solids nductivity, and ph] were studied, to simulate zamzam water in mekka saudi arabia. also, this designed electrical magnate in decreasing the tds of sea water ( nacl content), to convert it to water suitable for irrigation (tds<1000 ppm) was investigated in this work.the results show that the magnetic flux from our designed electrical magnate in the range of (0.0130.08) tesla and 30 minutes magnetic treatment time is sufficient to produce alkaline water with ph similar to zamzam water (ph from 7.85 while 60 minutes of magnetic treatment results to higher values of ph and the maximum ph value of 8.9 is obtained . the investigation for reducing the tds of water having 150 that , the maximum decrease in tds is took place when the magnetic flux is 0.013 tesla(coil and the time for magnetic treatment is 30 minutes where the tds of 1730 ppm reduced to 1290 ppm magnetic treatment on the ph change of high nacl content water give maximum ph value magnetic flux is 0.013 and 0.028 tesla (the voltages is 1.5 & 3 v respectively and 100 turn coil) and the time period nutes. the trend of results agreed well with previous studies, where the magnetic treatment lead always to increase of ph, decrease in tds and electrical conductivity magnetic water, alkaline water, design of electrical magnate, tds, ph magnetic water (mw) is the water which passed for a certain period of time through magnetic field [1]. mw is used in industry, agriculture and medical applications , in industry is used to prevent the scales from the inner tubes re it is used to increase the flowering of the fruits [2]. in medical applications, mw can be used to dissolve the stones in kidney and dissociating the salts of solid mass, it is also used to decrease the cholesterol and salts from arteries, decreasing the resistance of pumping the blood by the heart. in the broken bones the mw will increase the immigration of the calcium ions to the broken bones and accelerating the joining of the bones.; magnetic water increases the immunity cells in the body and helps to be a way from constipation. open the appetite and regulate the working of bile. drinking daily a cup of magnetic water will give the body with super animation and activating it [3]. drinking alkaline water decrease the epidemics of our body. water repre composition, so we should be well hydrated by water having beneficial minerals and which should be free from pollutants. good water have the ability of purifying the blood and strengthen the immune system and to counter the effect of free radicals. it was proven that water have many health promoting properties[4]. al-khwarizmi engineering journal (2015) study its efficiency alkaline magnetic suitable technical education electrical magnate was designed and constructed, the optimum magnetic flux and the effect of time on the physical properties of the alkaline (magnetic water) produced from the bottled drinking water [the total dissolved solids nductivity, and ph] were studied, to simulate zamzam water in mekka saudi arabia. also, designed electrical magnate in decreasing the tds of sea water (of 1500 ppm r irrigation (tds<1000 ppm) was investigated in this work.the results 0.08) tesla and 30 minutes h similar to zamzam water (ph from 7.858). to higher values of ph and the maximum ph value of 8.9 is obtained the investigation for reducing the tds of water having 1500 ppm nacl show tesla(coil of 100 turn and 1.5 v) and the time for magnetic treatment is 30 minutes where the tds of 1730 ppm reduced to 1290 ppm is obtained .the magnetic treatment on the ph change of high nacl content water give maximum ph value of 8.1 when the magnetic flux is 0.013 and 0.028 tesla (the voltages is 1.5 & 3 v respectively and 100 turn coil) and the time period studies, where the magnetic , tds, ph, zamzam water. accelerating the joining of the bones.; magnetic water increases the immunity cells in the body and to be a way from constipation. open the appetite and regulate the working of bile. drinking daily a cup of magnetic water will give the body with super animation and activating it drinking alkaline water decrease the epidemics of our body. water represent 70% of our body composition, so we should be well hydrated by water having beneficial minerals and which should be free from pollutants. good water have the ability of purifying the blood and strengthen the immune system and to counter the effect of free radicals. it was proven that water have many health promoting properties[4]. alaa dhari jawad al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 2835(2015) 29 the alkaline ionized water was made by splitting the filtered tap water into alkaline ionic water and acidic water. the first commercial ionizers for making alkaline water was available in japan in 1958. the magnetic treatment for water was used long times ago and the first commercial device used was in belgium in 1945[5]. magnetic field will change many physical properties of water as ph, tds and thus electrical conductivity, ph is normally increased and tds is decreased and thus electrical conductivity. magnetic field can be obtained from permanent or by electrical magnate. hardness of water changes as the magnetic intensity changes[6]. in this study, the optimum magnetic field intensities generated by an electric magnate and the optimum time required to get the required increase of the ph and decrease of tds and thus the electrical conductivity of the water were investigated. also, the effect of number of turns of the magnetic coil on the change of ph, tds and electrical conductivity properties of the treated water were investigated. the water treatment with magnetic phenomena has been reported effectively in numerous instances [7]. scale control from water by magnetic treatment is an increasing important role among chemical water conditioning methods. the use of magnetic field concentrated on permanent magnate [8] . crystallization of sparingly soluble diamagnetic salts of weak acids such as phosphates and carbonates is accelerated by use of magnetic field [9]. factors affecting the degree of water magnetizing are; force of magnetic field, quantity of water magnetized, and time of contact between the water and magnetic field [10]. when a current flows through a conductor, a magnetic field surrounds the conductor . the lines of magnetic field increases while the current flow increases. if a conductor is twisted in a coil, current will be generated when cutting the lines of magnetic field, when the number of turns of the coil is increased the magnetic field will be stronger, furthermore when the coil is wrapped around a piece of iron the current becomes stronger [11]. traditionally most people judge the properties of water from the standpoint of ph, in other words water is acidic or alkaline. the higher ph blood contains excess oxygen, the heart doesn't have to work so hard. drinking alkaline ionized water is beneficial for any health complaint where there is excess tissue acidity and damage being caused by free radicals. the list of specific diseases that have been connected with excess tissue acid waste and the damage done by harmful free radicals is extensive and includes the following: • cardiovascular disease including the building up of cholesterol deposits. • high blood pressure diabetes, • cancers, • hypothyroidism, • osteoporosis, • arthritis, • kidney problems, • gastro intestinal inflammation, • skin problems including eczema, gout, candida infections. zamzam water has healing effects. the prophet mohammed said: '' water of zamzam is good for whatever purpose it has been drunk''. concentrations of minerals in zamzam water and tap water is shown in table 1 [12]. table 1, chemical analysis of zamzam and tap water (ppm). mineral zamzam water tap water sodium 133 37.8 calcium 96 75.2 magnesium 38.88 6.8 potassium 43.3 2.7 bicarbonate 195.4 70.2 chloride 163.3 73.3 florid 0.72 0.28 nitrate 124.8 2.6 sulphate 124.0 107 tds alkaline 835 350 most of the previous works relating production of magnetic and alkaline water used commercial magnetizers composed of permanent magnate [1,5,13 ], but in our study electrical magnate was designed and constructed, the optimum magnetic flux and the effect of time on the physical properties of the alkaline (magnetic water) produced from the bottled drinking water [the total dissolved solids (tds) or the electrical conductivity, and ph] were studied, to simulate zamzam water in mekka saudi arabia. also, the efficiency of magnetic field from designed electrical magnate in decreasing the tds of sea water (of 1500 ppm nacl content), to convert it to water suitable for irrigation (tds<1000 ppm) was investigated in this work. alaa dhari jawad al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 2835(2015) 30 2. theory 2.1. the electromagnetic field the magnetic field from a wire carrying electrical current is a loop wraps the wire. the magnitude is decreased when increasing the distance from the wire. the magnitude of the magnetic field flux density (b) at a distance from a long straight wire carrying a current i is given by [14]: b=µ0i/2πr ...(1) where: µ0 is the permeability of free space equal to (4πx10-7 )t.m/amp ; t=tesla) the field at the center of the circular loop of radius r carrying a current i is given by: b=µ0i/2r …(2) for n loops aligned together to form a flat coil, the field is just multiplied by n such that: b=µ0ni/2r …(3) if a number of current carrying loops are stacked on top of each other to form a cylinder or, equivalently, a single wire is wound into a tight spiral, the result is known as solenoid. magnetic water treatment device is permanent magnets or electromagnets that attached to water lines in order to condition it. the amount of magnetic field in a coil is proportional to the current through the wire and multiplied by the number of turns of the coil (ni). [15]. fig. 1 the circuit of making electrical magnete. magnetic flux density 10,000 gauss (g)= 1tesla (t) the field along the axis of the solenoid has a magnitude of: b=µ0ni …(4) where n= n/l is the number of turns per unit length [14]. b and h are related by the permeability: b=µh[15] …(5) where h is the magnetic field strength. always the magnetic field is perpendicular to the direction of the current. the magnetic field generated from a loop of wire carrying a common mount of current is always weak magnetic field can be stronger with the same amount of current carrying in it by increasing the number of turns and making a coil. [16] 2.2. magnetic flux the unit of magnetic flux (φ) is webber (wb). one webber is equal to 1x108 magnetic field lines (wb=108 maxwell) = (tesla*m2). the magnetic flux density is related to magnetic flux such that: b=φ/a …(6) b= magnetic flux density in tesla (t) φ= magnetic flux in webbers (wb) a= area in square meters (m2) where the result is that in si unit for flux density is webbers per square meters (web/m2) 2.3. magneto motive force (mmf) is the strength of a magnetic field in a coil of wire. fm=ampere*turns=ni …(7) 2.4. field intensity h=fm/l=ni/l=at/m …(8) when the coil length decreased the intensity increased 2.5. relative permeability µ=µ/µ0 …(9) µ = straight or absolute permeability (t.m/amp.) µ0 = permeability of free space vacuum equal to (4π*10-7 t*m/amp.). 3. experimental work 3.1. materials bottled water and water having 1500 ppm nacl to simulate sea water are used. the instruments and details of materials used are as follows: drinking water (from bottles and water having 1500 ppm nacl to simulate sea water). alaa dhari jawad al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 2835(2015) 31 insulated copper wire type s.w.g. 19 diameter of 1mm. ova meter for measuring voltage, electrical current and resistance. ph meter allafrance company with 0.1 resolution. tds & electrical conductivity for water measurement device (ec/tds/temperature) made by hanna, h199301 in romania , having 0.01 ms/cm resolution for ec and 0.01ppt(g/l) resolution for tds. dc batteries of 1.5 v type d and 9 v battery. immersed water pump h=1.8m ,q=1200l/h and power 20 w . rubber tubes. galvanized iron bush of 10 cm length. table 2 shows the physical properties of water used in this study for magnetic treatment. table 2, specifications of bottled drinking water and sea water. electrical conductivity ms tds ppm ph type of water used no. 0.37 180 6.6 drinking water from bottles 1 3.47 1730 7.53 drinking water from bottles having 1500 ppm nacl (sea water) 2 3.2. design calculations the number of turns of the copper wire of 1 mm diameter and type swg 19 is taken as 100 turns in this work. the range of the magnetic flux density that will be used in producing magnetic water will be chosen such that: b = µ h …(10) where: µ= absolute magnetic permeability h: magnetic intensity at/m which is calculated as: h =f/l ...(11) where: f= ni …(12) f: magnetic force at n: number of turns of coil i: current, ampere l: length of magnetic lines m sample of calculations b=µh µr=5000 for iron, µ0 =4π x10-7 absolute permeability µr= µ/ µ0 assuming the magnetic flux needed is 0.01 tesla 0.01= 4π x10-7 x 5000 x h h= 0.01/4π x10-7 x 5000 h = 1.592 at/m h =f/l = ni / l = 100 i/0.1 (in our design the length of magnetic field = 10 cm = 0.1 m) i = 0.00159 a = 1.59 ma. from table 3 v=1.5 i=2.1 ma = 2.1x10-3a b= µ0. µr n.i/l = 4π x10-7 * 5000 * 100 *2.1x103/0.1 b=0.013 tesla water is tested by the ec/tds/ temperature device manufactured by hanna, h 199301 made in romania. 3.3. experimental procedure the experimental setup used for magnetic treatment to water in our study is as shown in fig. 2 and fig. 3. magnetic treatment are done on two types of water (drinking bottled water to produce alkaline water similar to zamzam water and bottled water having 1500 ppm nacl to simulate sea water to make it suitable for irrigation purposes). waters having (ph, tds, electrical conductivity) as given in table 1. the effectiveness of the designed magnetic treatment setup ,the optimum time and the optimum applied magnetic flux are investigated for getting the required change in ph which make the water of high alkaline suitable to health benefits and to make the sea water suitable for irrigation (low tds). the physical properties of water passed through the electrical copper coil were tested every 30 minutes. ph is tested by the portable ph meter made by allafrance company .the tds and the electrical conductivity of the water are tested by hanna,h 199301 romanian made. alaa dhari jawad al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 2835(2015) 32 fig. 2. pictures showing the system setup used in the magnetic treatment of water. fig. 3. layout showing the system setup used in the magnetic treatment of water (open circulation with a rate of circulation 1000-1200lt/h). two liter of water is used in each test to fill a plastic tank containing the immersed pump (h=1.8m, q=1200 lt/hr.) as shown in fig. 2 . the designed copper magnetic coil having 100 turns around the galvanized iron bush surrounding the rubber tube circulating the water from the tank. the circulation of water is continued for 120 minutes in each experiment and tests are made every 30 minutes for the physical properties of ph, tds and electrical conductivity. the range of magnetic flux density applied is (0.013 – 0.08) tesla as shown in table 3 below. the different magnetic flux densities used is obtained by using different voltages applied to the copper coil which gives different electrical current and then different magnetic force around the copper coil in which the water is moving across it as shown in table 1 to specify the optimum magnetic flux the copper coil wounded around galvanized iron bush of 10 cm length, of 2 cm inside diameter. ampere meter is used to measure the real electrical current passing through the copper coil and to be sure that the connections for the circuit is good. one dc battery of 1.5 v type d is used as power supply of 1.5 v and multiple 1.5 v batteries are used as power supply of (3, 4.5, 6 v) potential voltage. while one dc battery type of 9 v is used as 9 v power supply to get the required current in the copper coil. table 3, amount of magnetic flux generated with our designed electrical magnate of 100 turns according to voltage applied. 4. results figure 4 show the change of ph of drinking bottled water vs. time when magnetically treated. fig. 3 shows that, the treatment of drinking water whose specifications are given in table 2 with magnetic flux generated from a copper coil of 100 turns, diameter of copper wire is 1mm and using magnetic flux of range (0.013-0.08) tesla. results to an increase of ph and this is in compatible with researches related to this subject [1]. power supply(v) volt current (i) ma magnetic flux of electrical magnate of 100 turn( b ) tesla 1.5 2.1 0.013 3 4.5 0.028 4.5 6.4 0.04 6 8.5 0.056 9 12.8 0.08 rubber tube alaa dhari jawad al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 2835(2015) 33 fig. 4. the relationship of ph vs. time for magnetic treatment of bottled drinking water using different voltages potentials (magnetic flux densities). regarding the electrical conductivity (ec) & the total dissolved solids (tds) physical properties of water having 1500 ppm nacl (sea water) and magnetically treated, figures (5,6) show that the optimum voltages were 1.5 & 4.5 volts (0.013 & 0.04 tesla respectively) to decrease the value of tds and then the electrical conductivity of bottled drinking water. the minimum values reached for the tds are 1290 ppm with magnetic flux of 0.013 tesla and 1360 ppm with magnetic flux of 0.04 tesla. the minimum value of electrical conductivity which is 2.61 ms is reached with magnetic flux of 0.013 tesla .the period for magnetic treatment enough to achieve the above minimum values is 30 minutes only. fig. 5. effect of different voltages on the variation of tds for treated sea water(1500 ppm nacl) . fig. 6. effect of different voltages on the variation of electrical conductivity for treated sea water (1500 ppm nacl). figure 7 show the results of ph change of sea water (having 1500 ppm nacl) when was treated with magnetic fluxes in the range of (0.013 – 0.08) tesla. it can be noticed that at 30 minutes of magnetic treatment the maximum ph reached to 8.1 value when the magnetic flux is 0.013 tesla (13mt). when the magnetic treatment 60 minutes, ph reached a value of 8.4 with 0.056 tesla (56mt) magnetic flux. fig. 7. effect of different voltages on the variation of ph of treated sea water (1500ppm nacl ). 5. conclusions according to the discussion of the obtained results , the conclusions extracted are as follows: • using copper wire of swg 19 with 100 turns and potential dc voltages in the range (1.5,3,4.5,6,9) v is good for producing magnetic flux suitable for producing magnetic water and the capacity of production magnetic water during 30 minutes is two liters because our tank is of two liters , studies can be done on large tanks with large circulation rate water pumps. • the magnetic treatment for sea water with (1500 ppm nacl) by our designed electrical magnate 6 7 8 9 10 11 12 0 30 60 90 120 ph time minutes 1.5 v 3 v 4.5 v 6 v 9 v 1.2 1.4 1.6 1.8 0 30 60 90 120 150 t d s p p t time minutes 3v 6v 9v 1.5v 4.5v 2 2.5 3 3.5 4 0 30 60 90 120 150 e c m s time minutes 3v 6v 9v 1.5v 4.5v 12v 7.4 7.6 7.8 8 8.2 8.4 8.6 0 30 60 90 120 150 p h time minutes 3 v 6 v 9 v 1.5 v alaa dhari jawad al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 2835(2015) 34 is successful for decreasing the total dissolved salts (tds) and hence the electrical conductivity, also it is successful in increasing the ph for water which is desirable in using alkaline water for health ,irrigation , industrial and medical sectors. • increasing the magnetic flux by increasing the potential voltage applied will result to increase the time required to reach the required ph or may be resulting to inverse results (decrease in ph) , for example in our study we noticed that increasing the potential from 3 to 4.5 v a time required to get the ph of about 8.9 increased from 60 to 90 minutes , so a study should be done for every actual case to determine the optimum magnetic flux density and the time required to get the desired alkaline ph of water. • ph value of drinking water of 8.1 and 8.9 can be get easily by our designed electrical magnate with a magnetic treatment period of 60 minutes only and the magnetic flux density in the range of (0.013 – 0.08 ) tesla is very good for this job. 6. references [1] abdeltawab, rameen s., younes, mohammedadel a., ibrahim, ahmed, m., abdleaziz mohammed m.,''testing commercial water magnetizers: a study of tds and ph'', fifteenth international water technology conference, iwtc – 15 2011, alexandria, egypt, 2011. [2] http://www.moreplant.com/research/ files/ magnetic-water-demystified.pdf [3] www.3lom-mans montadalhilal.com/t9656topic [4] alkaline water :(www.water-forhealth.co.uk) [5] vemeiren, t., '' magnetic treatment of liquids for scale and corrosion prevention'', vol.5, pp215-219, 1958. technol. [6] banejad, h., abdosalehi , e., '' the effect of magnetic field on water hardness reducing'', thirteenth international water technology conference , iwtc 13 2009, hurghada, egypt, pp117-128. [7] kobe, s.g. drazic, p.j. mcguiness, j. strazisar, ''the influence of the magnetic field on the crystallization form of calcium carbonate and the testing of a magnetic water – treatment device'', journal of magnetism and magnetic materials, vol. 236, pp 7176,2001. [8] noran r. and shani u., ''effect of irrigation with magnetically treated water on the translocation of minerals in the soil,'' magn electr,sep,vol. 7, pp. 109-122,1996 [9] lipus, l.c. and dobersek , d.,'' influence of magnetic field on the aragonite precipitation '', chemical engineering science 62, 2089 2095, 2007. [10] bogatin, j., '' magnetic treatment of irrigation water: experimental results and application conditions, environ sci technol ,vol. 33 ,pp1280-1285,1999. [11] micromagnet.fsu.edu/electromag/electricity/g enerators. [12] nour al zuhair, rita khounganian,'' a comprehensive study between the chemical composition of potable water and zamzam water in saudi arabia'', .kfu faculty sites, retrieved august 15,2010 [13] mohamed, ahmed ibrahim,"effects of magnetized low quality water on soil properties and plant growth" international journal of research in chemistry and environment, vol. 3 issue 2 april 2013 (140147). [14] boston university, physics department , www.physics.bu.edu/py106/magfield.html [15] http://www.allaboutcircuits.com/textbook/dir ect-current/chpt-14/electromagnetism/ [16] biocera, the korean based company, alkaline water :www.water-for-health.co.uk )2015( 2835، :894، ا,06د011*(ا,5"ارز)3 ا,012/.ا,+*() '&ري #"اد ��ء ������ �� �� * ء�� ودرا"' ا���وط ا��&%$ #"�!�ا�� �� إ�� ج ����� وإ�� ء ��� ط�� و ا�� ء ا���� ط�.� و�0 �%' �� ه ا��2� �01%� / ��' �%.-� ا�� ء ا�,�ي �� ,7ء 6 ري 45اد ا��2 ھ.cا,>6(.b ا,>31a /ا,*&)6ا,>1a.ا,"/@?/ <=0اد –)026 ا,>;1","#.& 3eوg<;,h0 اigj,ا: bayati.engineer@gmail.com ا�!7/' k&lm -/درا bn3 وo&>g2m p.1&ط=( ء&reوإ b.+tn bn 0ي�&a,3 اu.ء ا,+=1&ط&+), -.o&iv.9,ا,5"اص ا ?)� x(v,ا g.yznو [l(h3 اu.ا,9.\ ا,+=1&ط bn إ#gاء ھ^ا ا,x( [+6 ا#] )x( . -2>&r )&ء ا,grب ا,+ph ((zj6(أو ا,>":.] ا,;3o&>g2 وا,0ا,ا,8&)_.) tds(ا,+"اد ا,j)tا,^اjoا,;(.(ا,+1>[ 3k -(g;+,3 );اk مv(ا:9)&ء ز"( c( ]<1+,ا,+&ء ا -.>g6,ا-i6"دu,3 . اo&>g2;,ا p.ا,+=1&ط x( ]<1+,3 اu.9&ءة ا,9.\ ا,+=1&طm -/درا bn e,^m &1)jf x( b+t+,ا -.);,ا -joح ا,^ا�(hا -.+m [.)an 3k)tds (g8j,ه ا&.( 3k ا,+"#"دة ) ،3au,3 ).&ه اk 05ام</�, i,&: g.j ء&(tds>1500 ( k)6#و 8,&:& 3au),)tds<1000ppm.( 0ى( x+' &1, 0o&6,3 اo&>g2;,ا p.ا,+=1&ط x( ]<1( 3u.1&ط=( \.k -k&lm نz> n8j,ا ]o&<e تg2أظ)0.08-0.013 ( �( �un -._(&8,ا,0ا,ا -.q&e x( مv(ا:9)&ء ز"+, k>&r( 0ي�&f ء&( ج&<es -+o)7.85-8 ( ةg<k x+'30و -.u.ا,+=1&ط -)(&ة ا,+6g<k ن";n &+1.> -a.fد � 0.028�i &(01;"ن k&lmا,9.\ ا,+=1&ط.un 3u&وي 8.9دt8e -a.f] �(? أ�bt دا,q&)_.)0aارھ& 60,(+&ء un .&<1,ت اg2أظ &+m ].)a<> -:&5,[ اo tds، أن أ�bt ا95e&ض ا,? x(1500ppm -.+m ا,+&ء ا,8&وي � -jue ?)�m i)( x( -.,&("ر0i ا,t"دi"م < -ju1�juetds -.,&ا,+"اد ا,^اjoا,;(. � 0q0.013ث �01 ا/>05ام k -k&lm.\ )=1&ط.0a( 3uاره un) &0ارھa( -.<,"k1.5 &0ارھa( 0د ,9&ت�و w,"k100 9, ( -.+m w_95eا n.qtds x( 1730 ppm ?,إppm 1290 ?)� ء ا,8&وي&+), -._(&ا,0ا,ا,8 g.=<, -ju1,&>1500وppm -._(&8,ا,0ا,ا w69n0 ارak م"iد"t,0 اiر")m i)( x(ph � 0.028و 08m0.013 أtf? �01 ا/>05ام k -k&lm.\ )=1&ط.0a( 3uاره 8.1إ,? un) -.<,"k1.5 3و xن )";<i x(? ا,>"ا,3 و)(� w,"k١٠٠ -9, ( we&m &+m ا,o&<1[ ا,c.+# c( -a9<( -(&6 ا,>a&رgi ا,+"3k -ay اhد<.&ت ا,6(+.ا,a>&uا,+>6(a<&,+"'"ع n.q ان )6&)(. دa.f ٣٠وز)0a( -*,&6( xاره �ح ا,^اjoا,;(.ا,+&ء <&,9.\ ا,+=1&ط.n 3u{دي داo+& ا,? زi&دة ا,0ا,ا,8&)_.وا95e&ض (hاtds 3o&>g2;,وا,>":.] ا. <4d6963726f736f667420576f7264202d2036342d373020dac8cf20c7e1e1e520cce3c7e120e6dac8c7d3> al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 15, no. 4, december, (2019) p. p. 6470 an experimental study on electrochemical grinding parameters on hardness and material removal rate for stainless steel 316 abdullah j. ghadban* abbas f. ibrahim** *,**department of production engineering and metallurgy/ university of technology * email: 71409@student.uotechnology.edu.iq ** email: abbasfadhel_2006@yahoo.com (received 23 april 2019; accepted 25 september 2019) https://doi.org/10.22153/kej.2019.09.006 abstract electrochemical grinding (ecg) process is a mechanically assisted electrochemical process for material processing. the process is able to successfully machine electrically conducting harder materials at faster rate with improved surface finish and dimensional control. this research studies the effect of applied current, electrolyte concentration, spindle speed and the gap between workpiece and tool on hardness and material removal rate during electrochemical grinding for stainless steel 316. the characteristic features of the electrochemical grinding process are explored through taguchi-design-based experimental studies. the better hardness can be obtained at 10 a of the current, 150 g/l of the electrolyte concentration, 0.3 mm of gap and spindle speed of 180 rpm, and the maximum material removal rate can be obtained at 40 a of the current, 250 g/l of the concentration, 0.2 mm of a gap and 180 rpm of spindle speed. keywords: electrochemical grinding (ecg, stainless steel 316, hardness, non-traditional machining. 1. introduction electrochemical grinding (ecg) is one of the hybrid electrochemical processes [1]. it consists of a combination of the mechanical grinding process and electrochemical machine (ecm). ecg procedure for removal metal requires a conductive grinding wheel with metal-bonded in which a negative charge as a cathode, workpiece with a positive charge as an anode, connected to dc power source and electrolyte solution in a gap between tool and workpiece. the electrolyte solution consists of water mixed with salt. the metal removal occurs in this process by electrochemical reaction which removes about (90% 95%), on the other hand the mechanical action is responsible for removal (5% 10%) [1]. the heat generates in this procedure is much less as compared to the traditional grinding process because most of the metal removal process occurs by electrolytic dissolution. the thermal residual stresses and heat-affected zone are not obtained during the ecg procedure [2]. electrolysis is performed at low voltage (5-25 v) so the quality of the function is not affected by the spark [3]. this process is productive, economical and has minimal effect on the useful properties of the material of the ecm process [1]. ecg has been well applied in machining tungsten carbide, stainless steel and metal-ceramic hard alloy of wc-co groups for improving surface safety [4-5]. t. m. a. maksoud [6] studied the effects of voltages and the electrolyte flow rate on material removal rate (mrr) and wheel wear. in addition to comparing it with a traditional grinding process. r. n. goswami [7] focused on studying the effect of electrolyte concentration, electrolyte flow rate, supply voltage and cutting depth on mrr and surface finish during ecg of the al2o3/ al interpenetrating phase compound. asit abdullah j. ghadban al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 6470 (2019) 65 baran puri [8]. evaluated the effect of cutting speed and voltages on composite carbide as a workpiece for finding optimum surface roughness and mrr by using response surface methodology (rsm). furthermore, zhang q.l., et al [9] studied the effect of voltage, electrolyte temperature and electrode feed rate on mrr. besides studying the use of the brazed diamond wheel instead of the diamond wheel used in the ecg process to prolong the life of the wheel. in this paper, ecg is employed to process stainless steel 316. experiments are done to study the effects of applied current, electrolyte concentration, gap size and spindle speed on hardness and mrr and improvement the hardness and mrr. the hardness: is the resistance of a material to plastic deformation. there are several hardness scales currently in use. the most common of which are brinell, rockwell, knoop, and vickers. rockwell hardness (hrc) is used in this experimental [10] and material removal rate: is one of the most important criterions to determine the machining efficiency in ecg process determined by ��� = � � , (g/min) …(1) where: � = �� − � …(2) wb = the weight of the workpiece before ecg operation in grams, wa = the weight of the workpiece after ecg operation in grams, t = the time of operation in minutes. 2. ecg theory 2.1. the design of experiment (doe) it is a branch of statistics which provides the experimenter with the methods for selecting the effective possible combinations or recipes of independent variables at which a limited number of experiments has been performed. there are many experimental design methods to create certain combinations of experiments. these combinations of experiments are called experimental design matrix (edm). the results of the planned experiments are used to investigate the sensitivity of the acquired dependent quality characteristics (qc), or the response, to the independent variables [11]. 2.2. taguchi approach taguchi’s comprehensive system of quality engineering is one of the greatest engineering achievements of the 20th century [12]. this method focuses on the effective application of engineering strategies rather than advanced statistical techniques [12]. the goals of taguchi’s approach can be summarized as designing robust products or processes that are insensitive to environmental conditions (external noise factors), developing robust products that are insensitive to component variation (internal noise factors), and minimizing variation around a target value. the most important parts of taguchi's approach are the reduction of variability and minimization of nonconformance cost. they are rational with the modern continuous quality improvement philosophy [13]. 2.3. analysis of variance (anova) it is one of the most critical tools for analyzing data from doe. the analysis of variance [14], which is a statistical technique is applied to reveal the level of significance of the influence of factors on a particular response. anova experiments can be very complex [15]; the analysis is conducted by using minitab 17 software that gives a table of anova. 3. experimental procedures fig. 1 shows a schematic setup diagram for electrochemical grinding. when machine conditions are applied, the rotary wheel is perpendicular to the workpiece. fig. 1. experimental set-up for ecg. in these experiments, a cylindrical diamond grinding wheel a metal-bonded is chosen as a abdullah j. ghadban al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 6470 (2019) 66 cathode tool as shown in fig. 2, and stainless steel 316 is chosen as anode workpiece. the dimensions of a workpiece are (60mm × 40mm × 2mm). fig. 2. cylindrical grinding wheel. table 1 shows the measured chemical composition of the workpiece by (spectrometer device in baghdad, iraq). table 1, chemical composition of the workpiece. elements % elements % c 0.057 cr 18.73 mn 1.769 mo 0.284 si 0.391 ni 8.69 p 0.035 fe bal. s <.0005 table 2 shows machining conditions used in this experiment. taguchi design used for this experimental, where sixteen experiments were conducted by using the taguchi method design with l16 (4^4) mixed orthogonal array as shown in table 3. table 2, machining conditions parameter value electrolyte nacl applied current (a) 10, 20, 30, 40 electrolyte con. (g/l) 100, 150, 200, 250 gap size (mm) 0.2, 0.3, 0.4, 0.5 spindle speed (rpm) 75, 150, 180, 280 electrolyte flow rate (l/s) 0.28 electrolyte temperature (°c) 28 table 3, distribution of parameters in the experiment exp. no. con. (g/l) current (a) gap (mm) speed (rpm) 1 100 10 0.2 75 2 100 20 0.3 150 3 100 30 0.4 180 4 100 40 0.5 280 5 150 10 0.3 180 6 150 20 0.2 280 7 150 30 0.5 75 8 150 40 0.4 150 9 200 10 0.4 280 10 200 20 0.5 180 11 200 30 0.2 150 12 200 40 0.3 75 13 250 10 0.5 150 14 250 20 0.4 75 15 250 30 0.3 280 16 250 40 0.2 180 maintaining hardness after an operation is necessary in the production environment and for higher productivity in the grinding process, a highest mrr is desirable; therefore, the hardness and mrr were classified as "larger is better" and the signal to noise ratio was calculated in this case as in the equation following [16]: snr = −10 log � � �∑ � �� �� ��� …(3) where: i = (1 to n), y is observed response value at each trail, n = number of observations in each trail. 4. results and discussion based on the experimental result presented in table 4, the effect of different process parameters on hardness and mrr was analyzed. abdullah j. ghadban al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 6470 (2019) 67 table 4, taguchi l16 orthogonal array and experimental result for hardness and mrr and their snr 4.1. results for hardness fig. 3 shows variations in hardness with applied current, electrolyte concentration, gap and spindle speed for four-level. from table 4, it appears that the better hardness can be obtained is 45.7 at 10a of the current, 150 g/l of the electrolyte concentration, 0.3 mm of gap and spindle speed of 180 rpm, it is preferable in manufacturing to maintain the value of hardness after operations. table 5 shows the anova and “f-test” values of contribution where it is noted the current as the most significant parameter on hardness. additionally, a gap size is the next significant parameter on hardness, and then electrolyte concentration. table 5, analyses of variance for hardness source df seq ss adj ss adj ms f concentration 3 65.43 65.43 21.81 0.60 current 3 804.15 804.15 268.05 7.39 gap size 3 80.92 80.92 26.97 0.74 spindle speed 3 75.02 75.02 25.01 0.69 residual error 3 108.77 108.77 36.26 total 15 1134.30 where: df=degree of freedom, seq ss= sum of a square, adj ss=adjacent sum of square, adj ms=adjacent mean square, f=fisher’s test. fig. 3. mean graph for hrc. it is observed from fig. 3 that the applied current had the most influence on hardness values. increasing current leads to a decrease in hardness, as increasing current leads to increased temperature in the reaction area that affects the microstructure of the workpiece. this eventually leads to a decrease in hardness of the workpiece. the effect of the electrolyte concentration and spindle speed are less than the current on hardness. fig. 4, fig. 5 and fig. 6 shows the effect of the current with the concentration, gap size and spindle speed on hardness. fig. 4 shows that the highest hardness can be maintained with the lowest applied current and the highest concentration. fig. 5 shows that the hardness decreases by reducing the gap when the current is stabilized. reducing the gap size causes increasing the machining current and fast anodic exp. no. con. (g/l) current (a) gap (mm) speed (rpm) hardness hrc hardness snr mrr (g/min) mrr snr 1 100 10 0.2 75 44.3 33,1602 0.09906 -20.0820 2 100 20 0.3 150 22.0 28,2995 0.23532 -12.5668 3 100 30 0.4 180 31.3 31.5957 0.26620 -11.4058 4 100 40 0.5 280 22.4 28.9432 0.32234 -9.8337 5 150 10 0.3 180 45.7 33.1602 0.10052 -19.9550 6 150 20 0.2 280 20.5 27.7833 0.26572 -11.5115 7 150 30 0.5 75 19.5 26.2351 0.22668 -12.8917 8 150 40 0.4 150 26.0 29.5424 0.36380 -8.7827 9 200 10 0.4 280 45.0 33.1602 0.10062 -19.9463 10 200 20 0.5 180 37.0 32.0412 0.18732 -14.5483 11 200 30 0.2 150 24.0 29.5424 0.28616 -10.8678 12 200 40 0.3 75 26.5 28.4649 0.36144 -8.8393 13 250 10 0.5 150 45.6 33.1793 0.10172 -19.8519 14 250 20 0.4 75 32.0 30.8814 0.21838 -13.2157 15 250 30 0.3 280 27.1 29.5424 0.26732 -11.4594 16 250 40 0.2 180 14.7 28.0280 0.57466 -4.8118 abdullah j. ghadban al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 6470 (2019) 68 dissolution in the gap between the workpiece and the tool, as a result, the mrr increases. while fig. 6 shows that speed has limited effect or even lacking the effect on hardness at constant current. fig. 4. surface of hrc vs con; current fig. 5. surface of hrc vs gap; current fig. 6. surface plot of hrc vs speed; current 4.2. results for mrr fig. 7 shows the variations of mrr (g/min) with applied current, electrolyte concentration, gap and spindle speed for four-level. from table 4, it is showed that the maximum mrr is 0.57466 g/min at a 40 a of current, concentration of 250 g/l, 0.2 mm of gap and spindle speed of 180 rpm. table 6 presents the anova and “f-test” values of contribution as it is noted that the current is the most significant parameter for maximum mrr and gap size as the next significant parameter for maximum mrr and then electrolyte concentration. table 6, analyses of variance for mrr source df seq ss adj ss adj ms f concentration 3 0.0095 0.0095 0.0031 1.24 current 3 0.1889 0.1889 0.0629 24.52 gap size 3 0.0202 0.0202 0.0067 2.62 spindle speed 3 0.0068 0.0068 0.0022 0.89 residual error 3 0.0077 0.0077 0.0025 total 15 0.2332 fig. 7. mean graph for mrr. it is found that the applied current and the gap has a highest significant effect on mrr while the concentration of electrolyte and spindle speed does not have a significant effect on material removal rate. mrr increases by increasing the current and concentration of the electrolyte while decreasing with increasing the amount of gap. increasing the speed to a certain level leads to increase mrr and then begins to decrease with the continued increase of spindle speed. the reason is the speed increased from (180 to 280) abdullah j. ghadban al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 6470 (2019) 69 rpm with used constant other parameters leading to reduce in reaction dissolution. 5. conclusions in this research, ecg is employed to machine stainless steel 316. conclusions could be summarized as follows: 1. the applied current has the most significant effect on the hardness and mrr while the other parameter has less effect on the hardness. 2. hardness decrease with increasing current and reducing the value of the gap. 3. mrr increases with increasing current, concentration of electrolyte and reducing the value of the gap. 4. the better hardness can be obtained is 45.7 at 10a of the current, 150 g/l of the electrolyte concentration, 0.3 mm of gap and spindle speed of 180 rpm. 5. the maximum mrr can be obtained is 0.57466 (g/min) at 40 a of the current, 250 g/l of the concentration, 0.2 mm of a gap and 180 rpm of spindle speed. 6. references [1] k. gupta, n. k. jain, and r. f. laubscher, “assisted hybrid machining processes,” springerbriefs appl. sci. technol., pp. 45–65, 2016. [2] d. s. patel, v. k. jain, and j. ramkumar, “electrochemical grinding,” nanofinishing sci. technol. basic adv. finish. polishing process., pp. 321–352, 2016. [3] a. b. puri and s. banerjee, “multiple-response optimization of electrochemical grinding characteristics through response surface methodology,” int. j. adv. manuf. technol., vol. 64, pp. 715–725, 2013. [4] t. kurita, c. endo, y. matsui, h. masuda, k. terasawa, f. tanaka, h. ikeda, k. oguchi, k. kobayashi, mechanical/electrochemical complex machining method for efficient, accurate, and environmentally benign process. int j mach tool manu; 48(15):1599-1604, 2008. [5] v.a mogilnikov., m.ya chmir., yu.s timofeev., v.s poluyanov. diamond ecm grinding of ceramic-metal tungsten. procedia cirp; 6:407–409, 2013. [6] t. m. a. maksoud and a. j. brooks, “electrochemical grinding of ceramic form tooling”, j. mater. process. tech., vol. 55, pp. 70–75, 1995. [7] r. n. goswami, s. mitra, and s. sarkar, “experimental investigation on electrochemical grinding (ecg) of aluminaaluminum interpenetrating phase composite,” int. j. adv. manuf. technol., vol. 40, pp. 729– 741, 2009. [8] a. b. puri and s. banerjee, “multiple-response optimization of electrochemical grinding characteristics through response surface methodology,” int. j. adv. manuf. technol., vol. 64, pp. 715–725, 2013. [9] n. s. qu, q. l. zhang, x. l. fang, e. k. ye, and d. zhu, “experimental investigation on electrochemical grinding of inconel 718,” procedia cirp, vol. 35, pp. 16–19, 2015. [10] s. berczyński, d. grochała, and z. grządziel, “simulation of the process of metal hardness measurement by the rockwell method,” new trends prod. eng., vol. 1, pp. 647–654, 2018. [11] h. kim "statistical modeling of simulation errors and three reductions via response surface technique" a dissertation submitted to the faculty of the virginia polytechnic institute and state university, 2001. [12] r. garg “effect of process parameters on performance measures of wire electrical discharge machining” ph.d. thesis mechanical engineering department national institute of technology haryana, india. 2010. [13] l. chen “integrated robust design using response surface methodology and constrained optimization” m.sc. thesis systems design engineering university of waterloo canada 2008. [14] h. n. ugla, "taguchi experimental design and analysis for effective water pump shaft parameters", m.sc. thesis, university of technology, department of production and metallurgy engineering, baghdad, 2013. [15] m. f. triola, "essentials of statistics", 2nded, pearson education inc., usa, 2005. [16] n. l. gupta “optimization of micro – wire edm operation using grey taguchi method” thesis of bachelor of technology, department of mechanical engineering national institute of technology, rourkela, may 2011. )2019( 6470، صفحة 4العدد ، 15دجلة الخوارزمي الهندسية المجلم عبد هللا جمال غضبان 70 دراسة تجريبية في عوامل التنعيم الكهروكيميائية على الصالدة ومعدل إزالة المواد للفوالذ ٣١٦المقاوم للصدأ **عباس فاضل ابراهيم *عبدهللا جمال غضبان ةالتكنولوجي ةالجامع تاج والمعادن/قسم هندسة االن،*** 71409@student.uotechnology.edu.iq :البريد االلكتروني* abbasfadhel_2006@yahoo.com : البريد االلكتروني** الخالصة قادرة على تشغيل المواد الصلبة ذات التوصيل الكهربائي انها اذعملية القطع الكهروكيميائية عملية كهروكيميائية بمساعدة ميكانيكية لتشغيل المادة. تعد ليت والسرعة الدورانية والفجوة بين المشغولة واألداة اإللكترويدرس هذا البحث تأثير التيار وتركيز بمعدل أسرع مع تحسين السطح والتحكم في دقة األبعاد. حيث تم دراسة الخواص لعملية التنعيم الكهروكيميائية من ٣١٦يميائية للفوالذ المقاوم للصدأ على الصالدة ومعدل إزالة المادة أثناء عملية التنعيم الكهروك ملم من ٠٫٣ليت واإللكتروغم/لتر من تركيز ١٥٠أمبير و ١٠خالل دراسة تجريبية مستندة إلى تصميم تاكوجي وتم الحصول على أفضل صالدة عند تيار ليت و اإللكتروغم/لتر من تركيز ٢٥٠امبير و ٤٠دقيقة وكما تم الحصول على اعلى معدل إلزالة المادة عند التيار دورة في ال ١٨٠الفجوة وبسرعة دورانية .دورة في الدقيقة ١٨٠ملم من الفجوة وبسرعة الدوران ٠٫٢ 11-19 al-khwarizmi engineering journal,vol. 11, no. deflection analysis of an elastic single link robotic manipulator rafal m. *department of automated manufacturing engineering **department of biomedical engineering (received abstract robotics manipulators with structural flexibility provide an attractive alternative to rigid robotics manipulators for many of the new and evolving applications in robotics. in certain applications their use is unavoidable. the increased complexity in modeling and control of such manipulators is offset by desirable performance enhancements in some respects. in this paperthe singlelink flexible robotics manipulator designed with 0.5 m length , 0.02 m width and with 0.004 m thickness with mass located at the tip. there are four subsystems; motion, control, accelerometer and robotics manipulator is the base servomotor. it rotates a hub with the link on it and measure the tip deflection. the deflection was measured for three cases without load, with 27.5 and with 59.4 gram at the end of the flexible link . during each of the above cases i rotated the base servo motor at card based on atmega640 microcontroller. measured by mma7631 accelerometer then the datai collected collected from accelerometer and plot it using matlab software and compared between theoretical results obtained from matlab program that based on lagrange equation of motion and experimental results and we found the maximum deflection occurred when v=180 deg/sec a keywords: flexible link manipulator , industrial robotics , 1. introduction robotic manipulators are used widely in dangerous, monotonous, and boring of these robotic manipulators are build and manner to maximize stiffness and to minimize the vibration of the end effectors to achi position accuracy. the design of manipulator is achieved by using heavy material and a bulky design. the existing heavy manipulators are known to be insufficient in te of speed and power consumption with respect to the operating payload [1]. to improve industrial productivity robotics, it is required to increase the operation speed of the link and/or reduce the weight of the links. due to high speed operation and requirements, a dynamic model that includes the joint and / or link flexibilities is needed. khwarizmi engineering journal,vol. 11, no. 3, p.p. 11-19 (2015) deflection analysis of an elastic single link robotic manipulator rafal m. khalil* somer m. nacy** department of automated manufacturing engineering/ al-khwarizmi college of engineering department of biomedical engineering/ al-khwarizmi college of engineering/ university of *e-mail:rafalalazzawi90@gmail.com **e-mail :somernacy@yahoo.com (received 22 june 2014; accepted 7 may 2015) robotics manipulators with structural flexibility provide an attractive alternative to rigid robotics manipulators for many of the new and evolving applications in robotics. in certain applications their use is unavoidable. the increased ling and control of such manipulators is offset by desirable performance enhancements in some link flexible robotics manipulator was designed and implemented designed with 0.5 m length , 0.02 m width and with 0.004 m thickness with mass located at the tip. there are four motion, control, accelerometer and gyro and a host computer subsystem. the work principle of single s manipulator is the base servomotor. it rotates a hub with the link on it and measure the tip deflection. the for three cases without load, with 27.5 and with 59.4 gram at the end of the flexible link . rotated the base servo motor at an angular velocity equals to 90 deg./s using control atmega640 microcontroller. the deflection was measured for the three cases and the deflection measured by mma7631 accelerometer and gyro . this accelerometer controlled by using mega arduino board . from accelerometer and plot it using matlab software and compared between theoretical results obtained from matlab program that based on lagrange equation of motion and experimental and we found the maximum deflection occurred when v=180 deg/sec and tip load=59.5 gram anipulator , industrial robotics , robotics manipulator ,beam deflection widely to help boring jobs. most build and in a to minimize the vibration of the end effectors to achieve good position accuracy. the design of high stiffness is achieved by using heavy material existing heavy and rigid manipulators are known to be insufficient in terms with respect to improve industrial productivity of the increase the operation reduce the weight of the to high speed operation and lightweight dynamic model that includes the is needed. the link flexibility is a consequence of the lightweight structure in manipulator arms that are modeled and designed to operate at high speeds with low inertia. compared conventional heavy and bulky robots weight robot, by introducing flexibility on the mechanical system of robots, it has a great advantages of larger work volume, and lower cost, payload-to-manipulator-weight ratio, lower energy consumption, smaller actuators, better transportability, better maneuver ability end of these advantages its reduced inertia [2]. these great disadvantage obtained by introducing joint and / or link robotics mechanical system, vibration due to low stiffness. if cannot be solved, then the al-khwarizmi engineering journal (2015) deflection analysis of an elastic single link robotic manipulator khwarizmi college of engineering/ university of baghdad university of baghdad robotics manipulators with structural flexibility provide an attractive alternative to rigid robotics manipulators for many of the new and evolving applications in robotics. in certain applications their use is unavoidable. the increased ling and control of such manipulators is offset by desirable performance enhancements in some designed and implemented from perspex and designed with 0.5 m length , 0.02 m width and with 0.004 m thickness with mass located at the tip. there are four gyro and a host computer subsystem. the work principle of single-link s manipulator is the base servomotor. it rotates a hub with the link on it and measure the tip deflection. the for three cases without load, with 27.5 and with 59.4 gram at the end of the flexible link . equals to 90 deg./s using control for the three cases and the deflection by using mega arduino board . from accelerometer and plot it using matlab software and compared between theoretical results obtained from matlab program that based on lagrange equation of motion and experimental nd tip load=59.5 gram. beam deflection. link flexibility is a consequence of the in manipulator arms that are operate at high operation speeds with low inertia. compared between the conventional heavy and bulky robots and light by introducing joints and /or link the mechanical system of robots, it advantages of higher operation speed, and lower cost, greater weight ratio, lower smaller actuators, better better maneuver ability and at the end of these advantages its safer operation due to disadvantage obtained by and / or link flexibilities to system, that system has high vibration due to low stiffness. if that problem the mechanical system of rafal m. khalil the robot will not been favored in industries will affect the repeatability and accuracy of end point of manipulator in response to input commands. to overcome this problem, an accurate dynamic model of the manipulator characterize with joint and/or link to be developed. this is a first step modeling and designing an efficient control strategies for these manipulators [3]. before study of flexible manipulator construction materials must be focused on efficient actuation and sensing technologies , and simple and effective controller designs. flexible robot manipulators are in use in some extent in space applications. this is because of the weight resurrection for a spacecraft ,other potential areas of application are manipulation in nuclear and other hazardous environment , car painting, manufacturing of electronic hardware and food industry[4]. cannon and schmitz [5], studied single flexible manipulators shown in fig.1 lagrange’s equation and the assumed mode method for modeling the single link manipulator and the vibration is controlled by measuring the position and using strain gauges have to be very useful for achieving good fig. 1. flexible link manipulator. nagarajan and turcic [6], derived motion using lagrange’s equation for elastic mechanism systems. the elastic links are modeled using the finite element method. both rigid body degrees of freedom and the elastic degrees of freedom are considered as generalized coordinates in the derivation. choi et al. [7] ,”addressed the control dynamic modeling of a single manipulator fabricated from composite laminates (nonmetallic) and compared the results with that of aluminum. they have shown that the manipulator fabricated from composite laminates has superior performance characteristics such as al-khwarizmi engineering journal, vol. 11, no. 12 industries. this accuracy of the in response to input overcome this problem, an accurate manipulator that can flexibility has to be developed. this is a first step towards designing an efficient controlling for these manipulators [3]. before study of flexible manipulator the must be focused on , actuation and sensing technologies , and simple and effective controller designs. flexible are in use in some extent in space applications. this is because of the weight resurrection for a spacecraft ,other potential areas are manipulation in nuclear and other hazardous environment , car/vehicle painting, manufacturing of electronic hardware , studied single-link shown in fig.1 using the lagrange’s equation and the assumed mode method for modeling the single link manipulator s controlled by measuring the ave been found good performance. flexible link manipulator. [1] derived equations of motion using lagrange’s equation for elastic the elastic links are modeled using the finite element method. both rigid body degrees of elastic degrees of freedom are considered as generalized coordinates in the control and the dynamic modeling of a single-link flexible manipulator fabricated from composite laminates the results with that of aluminum. they have shown that the manipulator fabricated from composite laminates characteristics such as faster settling time, smaller input torque and smaller overshoot relative to the manipulator fabricated from aluminum discussed the utilization of composite materials in the construction of a flexible manipulator to provide higher strength and stiffness ratio and larger structural damping than a metallic flexible manipulator . krishnamurthy et al. [9], model for single-link robotic arms fabricated from orthotropic composite materials. the equations of motion are derived using hamilton's principle and include the coupling between the rigid body motion and elastic motion results presented for aluminum, steel, graphite/epoxy, and boron/epoxy indicate that the motion-induced vibration is significantly less for the composite robotic arms as well as substantial savings in energy”. so i made our flexible link manipulator from composite material its most preferred because of its light weight and high strength and large structural damping 2. characteristics of the physical arm the schematic of a planar manipulator is shown in fig. inertial coordinate frame, and coordinate assigned for a flexible link. an d τ represent the hub position, the deflection do in the arm, and the torque applied to respectively. the existing experimental single link flexible manipulator is a 0.5 flexible structure that can plane but it can’t bend the vertical plane. at end of the arm the different load was putted and at the other end was clamped on a rigid hub from teflon material mounted directly on the haft of a dc servo motor. a torque applied by the dc servo motor rotates the arm in a horizontal plane. the other end of the arm with payload mass attached is free. the beam of the manipulator is made of perspex fig. 2. a planar single-link flexible manipulator. khwarizmi engineering journal, vol. 11, no. 3, p.p. 1119(2015) faster settling time, smaller input torque and smaller overshoot relative to the manipulator cated from aluminum “. choi et al.[8] , discussed the utilization of composite materials in the construction of a flexible manipulator to provide higher strength and stiffness-to-weight ratio and larger structural damping than a metallic [9], “present a dynamic link robotic arms fabricated from orthotropic composite materials. the equations of motion are derived using hamilton's principle and include the coupling between the rigid body otion and elastic motion. computer simulated results presented for aluminum, steel, graphite/epoxy, and boron/epoxy indicate that the induced vibration is significantly less for the composite robotic arms as well as substantial o i made our flexible link manipulator from composite material its most preferred because of its light weight and high strength and large structural damping. characteristics of the physical arm the schematic of a planar single-link flexible manipulator is shown in fig. 2, (x0,y 0) is an inertial coordinate frame, and ( x 1 ,y 1)is the coordinate assigned for a flexible link. θ,ψ(x ,t), represent the hub position, the deflection do the torque applied to the hub, the existing experimental singlelink flexible manipulator is a 0.5 m long, a flexible structure that can bend in the horizontal the vertical plane. at the the different load was putted and at clamped on a rigid hub made mounted directly on the haft torque applied by the dc servo motor rotates the arm in a horizontal plane. the other end of the arm with payload mass attached is free. manipulator is made of perspex. link flexible manipulator. rafal m. khalil al-khwarizmi engineering journal, vol. 11, no. 3, p.p. 1119(2015) 13 3. mechanical system modeling the equations of motion of this system involving a rotary flexible link manipulator, involves modeling the rigid rotational base and the flexible link together as rigid bodies. a simplification of the partial differential equation describe the motion of a the flexible link, a single degree of freedom approximation in this system is used. at the first start with the derivation of the dynamic model of the system by computing various rotational moments of inertia terms. the rotational inertia for a flexible link is given by: j���� = �� m����l� …(1) where: l is the total flexible link length , and mlink is the total mass of the flexible link, for a single degree of freedom of this system, the natural frequency is related with torsional stiffness of the link and rotational inertia in the following manner: ω�� ���������� … (2) where: ��n was found experimentally and kstiff is the lateral stiffness constant of the link ,defined as:������ = �� … (3) where: f is the force applied at the tip of the link and is the tip deflection. = � !"� #$ … (4) and substitutes equation (4) into equation (3) yields the flexural stiffness of cantilever beam :������ = � #$!" … (5) where i is the moment of area of the link and e is the young modules of elasticity of the link. in addition, any frictional damping effects between the flexible link and the rotary base was neglected. next, the generalized dynamic equation of the system was driven for the tip and base using the lagrange’s energy equations of motion in terms of a set of generalized variables phi θ and alpha α ,where α is the angle of tip deflection and θ is the base rotation given in the following:%%� & %'%(′) − %'%( + %,%( = -( … (6) where: p is the total potential energy of the system and t is the total kinetic energy of the system, and qi is the ith generalized force within the ith degree of freedom. the virtual forces that applied onto the generalized coordinates obtained from qθand qα, be: -(./ … (7) -0 = 0 … (8) the dynamic equations was driven for the mechanical subsystem from: 2 .. = − 4567889:;5< = + �9:;5< / … (9) = .. = −������ & �9:;5< + �9:;5<) = + �9:;5< / … (10) next, rewriting equations (9) and (10) into a state space form that gives the following equation[10]: >2?=?2@=@ a = bc cc d00 00 1 00 10 − 4567889:;5< 0 00 −������ & �9:;5< + �9:;5<) 0 0fg gg h >2=2?=? a + bcc cd 00�9:;5<�9:;5<fgg gh / …(11) 4. mathematical design table 1, physical parameters of the system. parameter values l* h * b (arm dim.) 0.5 * 0.02 *0.004m e (modules of elasticity ) 2.1 gpa m (link mass) 0.041 kg mt (tip payload) 0, 0.0595,0.0274 kg jb(inertia of the base) 0.0229 kg.m2 t (motor torque const.) 7,15.5 kg-cm • t ( torque) = 1.520 n-m • kg (motor gear ration ) = 2:1 • vf= (feed voltage)=6 , 12 v the matlab program built to find the tip deflection based on lagrange equation [10] of motion as mention above and derived using my parameter shown in table 1.1 .the ordinary differential equation (eq.11) solved using laplace inverse to find the tip deflection. 5. experimental work 5.1. design and implementation of single link flexible manipulator the single link flexible manipulator has been designed and manufactured in the al-khwarizmi engineering college workshop; the basic components that have been used to form the flexible manipulator illustrated as following: (1) high torque servo motor (changeable velocities), (2) teflon hub with radius (0.0615m), with a width of (0.09 m), (3) rotating base two layer with radius (0.2m) , with a space between them equal (0.05 m) and thickness equal rafal m. khalil al-khwarizmi engineering journal, vol. 11, no. 3, p.p. 1119(2015) 14 (0.005 m). (4) two aluminum fixed plate, (5) perspex link with length (0.520 m) , with width of (0.042 m) and with thickness (0.004 m). (6) power supply to control the velocity of servo motors,(7) mma 7631 accelerometer + gyro sensor to measure the tip deflection of the flexible link, (8) arduino mega 2560 board to control the accelerometer + gyro, (9) servo motor control card to control the angle and velocity of the base servo motor . the manufacturing of the flexible link has been done by the following steps: (a) the hub was turning to cylindrical shape with 6.15 mm radius. (b) the perspex plate was cutting using laser beam cutting to the dimension mention previously . (c) the aluminum plate shaped to fix the perspex link with the teflon hub . (d) the teflon hub with the flexible link mounted above the rotating base and the base servo motor inside the rotating base . (e) put the load at the end the flexible link and stick the accelerometer on it. the single link flexible manipulator shown in figures below: fig. 3. hub with rotating base. the side , front and top view was drawn using autocad software as shown in figure 4,5,and 6: fig. 4. flexible link manipulator. fig. 5. flexible link manipulator (side view ). fig. 5. flexible link manipulator (side view ). fig. 6. (a) flexible link manipulator (front view), (b) aluminum fix plate. fig. 7. flexible link manipulator (top view). hub perspex link load rotating base base servo motor (a) (b) rafal m. khalil al-khwarizmi engineering journal, vol. 11, no. 3, p.p. 1119(2015) 15 5.2. control part the single link flexible manipulator rotate horizontally using high torque servo motor and this is motor was controlled by servo motor control card based on atmega640. the velocity and the angle of the servo motor controlled through graphical user interface gui of servo motion software built in with this card.the mma7631 accelerometer + gyro sensor , its block diagram shown in ( fig. 8).stick at the tip of the link and this is sensor controlled by arduino mega 2560 board. the program built using arduino language and this is language based on c++language . fig. 8. simplified accelerometer functional block diagram. 6. results and discussion 6.1. theoretical results the theoretical results obtained from matlab software.. the matlab program was built based on lagrange equation. the tip load was changed and the motor velocity also changed and measured the deflection, as shown in the results below: fig. 9. tip deflection at tip load=0 gram. fig. 9 shows the variation of tip deflection with time for two velocity (90 and 180) degree/sec. and for tip attached mass equals zero gram. it shows that a time passes, the deflection fluctuates between a values. for v=90 degree/sec. blue curve, maximum value was found to be (4.6 mm). for v=180 degree/sec. red curve, maximum value was found to be (9.9 mm).this figure also shows that the maximum tip deflection values decreases as the velocity of the servo motor decrease from 180 to 90 degrees/sec. fig. 10. tip deflection at tip load=27.4 gram. fig. 10 shows the variation of tip deflection with time for two velocity (90 and 180) degree/sec. and for tip attached mass equals 27.4 gram. it shows that a time passes, the deflection fluctuates between a values. for v=90 degree/sec. rafal m. khalil al-khwarizmi engineering journal, vol. 11, no. 3, p.p. 1119(2015) 16 blue curve, maximum value was found to be (6.1 mm). for v=180 degree/sec .red curve, maximum value was found to be (1.31cm).this figure also shows that the maximum tip deflection values decreases as the velocity of the servo motor decrease from 180 to 90 degrees/sec. fig. 11. tip deflection at tip load=59.5 gram. fig. 11 shows the variation of tip deflection with time for two velocity (90 and 180)degree/sec. and for tip attached mass equals 59.5 gram. it shows that a time passes, the deflection fluctuates between a values. for v=90 degree/sec. blue curve, maximum value was found to be (7.8 mm). for v=180 degree/sec. red curve, maximum value was found to be (1.67cm).this figure also shows that the maximum tip deflection values decreases as the velocity of the servo motor decrease from 180 to 90 degrees/sec. 6.2. experimental results the experimental results were obtained from the single link flexible manipulator and the tip deflection measured using accelerometer stick at the end of the link .the results were taken when the base servo motor operated at velocity equal (90,180) degrees/sec and for 120 degrees using servo motor control card gui and for three different loads. the experimental results were shown below: fig. 12. experimental tip deflection at tip load=0 gram. fig. 12 shows the variation of tip deflection with time for two velocity (90 and 180) degree/sec. and for tip attached mass equals zero gram. it shows that a time passes, the deflection fluctuates between a values. for v=90 degree/sec. blue curve, maximum value was found to be (7 mm). for v=180 degree/sec. red curve, maximum value was found to be (1.2cm).this figure also shows that the maximum tip deflection values decreases as the velocity of the servo motor decrease from 180 to 90 degrees/sec. fig. 13. experimental tip deflection at tip load=27.4 gram. fig. 13 shows the variation of tip deflection with time for two velocity (90 and 180) degree/sec. and for tip attached mass equals 27.4 gram. it shows that a time passes, the deflection fluctuates between a values. for v=90 degree/sec. blue curve, maximum value was found to be (9.4 mm). for v=180 degree/sec. red curve, maximum value was found to be (1.72cm).this figure also shows that the maximum tip deflection values rafal m. khalil al-khwarizmi engineering journal, vol. 11, no. 3, p.p. 1119(2015) 17 decreases as the velocity of the servo motor decrease from 180 to 90 degrees/sec. fig. 14. experimental tip deflection at tip load=59.5 gram. fig. 14 shows the variation of tip deflection with time for two velocity (90 and 180) degree/sec. and for tip attached mass equals 59.5 gram. it shows that a time passes, the deflection fluctuates between a values. for v=90 degree/sec. blue curve, maximum value was found to be (1.3 cm). for v=180 degree/sec. red curve, maximum value was found to be (1.96cm).this figure also shows that the maximum tip deflection values decreases as the velocity of the servo motor decrease from 180 to 90 degrees/sec. table 2, theoretical &experimental tip deflection result at different load. motor velocity (deg/s) tip load (gram) theoretical max. tip deflection (mm) experimental max. tip deflection(mm) percentage difference v=90 zero 4.6 7 34 % v=180 9.9 12 17.5% v=90 27.4 6.1 9.4 35 % v=180 13.1 17.2 23.8 % v=90 59.5 7.8 13 40% v=180 16.7 19.6 7. conclusions the concluding remarks withdrawn from the obtained results as following: • load: maximum tip deflection of the flexible link increases as the tip attached mass increases from 0, 27.4 and 59.5 gram as shown in result obtained previously . • velocity: the deflection of the flexible link increases as the velocity of the base servo motor angle increases from [90-180] degrees/sec as shown in (table:1). • damping effect: the damping effect is clear after approximately 5 second and obvious in the experimental results only because we neglect the damping effect at the theoretical part. 8. references [1] aarts r.g.k.m. and jonker j.b.," dynamic simulation of planar flexible link manipulators using adaptive modal integration", multibody system dynamics, vol.7, pp. 31–50, 2002. [2] shaheed m.h. andtokhi m.o., "dynamic modeling of a single-link flexible manipulator: parametric and non-parametric approaches" robotica, vol.20, pp. 93–109, 2002. [3] sciavicco, l., and siciliano, b., "modeling and control of robot manipulators", springer london, 2004. [4] book ,m.o. tokhi and a.k.m. azad,"flexible robot manipulator ,modeling, simulation and control" , the institution of engineering and technology, series 68 ,pp. 19-20,2008. [5] cannon r.h. and schmitz e., "initial experiments on end-point control of a flexible one-link robot", the international journal of robotics research vol.3, no.3, pp.62–75, 1984. [6] nagarajan s. and turcic d.a., "lagrangian formulation of the equations of motion for the elastic mechanisms with mutual dependencebetween rigid body and elastic motions", part 1: element level equations, rafal m. khalil al-khwarizmi engineering journal, vol. 11, no. 3, p.p. 1119(2015) 18 and part ii: system equations, asme journal of dynamic systems, measurement, and control, vol.112, no. 2, pp.203–214, and pp.215–224, 1990. [7] choi s.b., thompson b.s. and gandhi m.v., "modeling and control of a single-link flexible manipulator featuring a graphite– epoxycomposite arm", proceedings of the ieee international conference on robotics and automation, vol.2, pp.1450–1455, 1990. [8] choi, s.b., gandhi, m.v. and thompson,b. s., "an experimental investigation of an articulating robotic manipulator with a graphite epoxy arm". journal of robotic systems, vol.5, pp.73–79, 1988. [9] krishnamurthy k., chandrashekhara k. and roy s., "a study of single-link robots fabricated from orthotropic composite materials", computers and structures, vol.136, no.1, pp.139–146, 1990. [10] m. o. tokhi and a. k. m. azad,”modelling of a single-link flexible manipulator system: theoretical and practical investigations”, robotica , v.14,no.1,pp.91-102,1996. )2015( 1119، ���� 3، ا�� د11 ا���ارز� ا��� �� ا����� � � �لر�ل ���د 19 &���% ا$��اف ذراع رو��ت ��ن ا��دي ا����� %��' داوود *ر)% ���)� ��� ** � ا������ ا��������� ا�)'ارز$#/ "! ھ����اد/ +*�� ا�(�-. �/$01 * � ا�34 ا��0�2 ��� ا�)'ارز$# / #"! ھ����اد/ +*�� ا�(�-. �/$01 ** rafalalazzawi90@gmail.com :ا�;7:� ا7�8�9و#5 somernacy@yahoo.com :ا�;7:� ا7�8�9و#5 ا��*�� � ذات ا�(�8*�� ا��a57 ھ# .�:@ ا+?7 <0=�ان �d00ر5 ةاط7اف ا�7و.'ا�0ت ا���h$�� ذات ا�(�8*�� ا��*;� ا .iط7اف �d0وان �7و.'�0ت ا��� j$ �:�/*� �:�k0ت ا�h�;40ل ا�7و.'�0ت ةا��k$ #> ا��.وا���4'رة m/. #>4�$ 7n$ 9 7$ا a57ام ا9ط7اف ا���(��� ا����� وا��82 ھpاa و :0h�; @.0hت ا�h/� #> ز:0دة j�!2� 0دة:q� ه ا9ط7افp).0)=ادا .pھ #>s2;راع $��'ع $ ا ا�pا ا�pوھ #d0�u 7و.'ت� �vذراع $7ن وا p�nم .���� و��'h5 w8;�.4'ل j $0دة ا�;7:0 � ا�pراع$�7 ٠.٠٠٤ ^$�7 و�� 7d٠.٠٢ض ، 7�$ ٠.٥:5(0 #> a�;?$ �� 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determination of welding velocity and arc energy for fusion mag welding joint salah sabeeh abed-alkareem department of machines and agricultural equipment / university of baghdad email: dr.salah2007@yahoo.com (received 22 april 2014; accepted 27 september 2014) abstract this paper is an experimental work to determinate the effect of welding velocity and formed arc energy for co2mag fusion weld pool. the input parameters (arc voltage, wire feed speed and gas flow rate) were investigated to find their effects on the weld joint efficiency. design of experiment with response surface methodology technique was used to build empirical mathematical models for welding velocity and arc energy in term of the input welding parameters. the predicted quadratic models were statistically checked for adequacy purpose by anova analysis. additionally, numerical optimization was conducted to obtain the optimum values for welding velocity and arc energy. a good agreement was found between experimental and predicted results. keywords: welding velocity, arc energy, mathematical modeling, numerical optimization, joint efficiency. 1. introduction carbon dioxide, as inert gas is normally considered effective in mag welding process, since the heat of the arc breaks down the co2 into carbon monoxide and free oxygen. the oxygen will combine with elements transferring across the arc to form the oxides which are released from the weld pool in the form of slag and scale. although co2 is an active gas and produces an oxidizing effect, efficient joint welds are achieved almost free of porosity and weld defects. co2 is widely used for welding mostly for low carbon steel due to its common availability, quality weld efficiency and low cost [1]. co2 -mag is an electric arc welding process which joins metals by heating them with an arc established between the electrode and the work. industrially, co2-mag welding is one of the most important processes for welding sheet metal engineering applications, such as automobiles, structures and marine parts. co2-mag welding is versatile, gives very little loss of alloying elements and can be operated as semi as well as fully automated. many commercial metals can be welded by the co2mag process, including carbon steels, stainless steels, aluminum, copper and nickel alloys [2]. the recommended arc energy (rate of heat input) results in good mechanical properties in the heat affected zone. the rate of heat input supplied by the welding process affects the efficiency of the welded joint. this is described by the arc energy that can be calculated taking in account arc voltage, welding current and speed of welding [3]. arc energy is one of the most important process parameters in controlling weld response. it can be referred to as an electrical energy supplied by the welding arc to the weldment. in practice, however, arc energy can approximately (i.e., if the arc efficiency is not taken into consideration) be characterized as the ratio of the arc power supplied to the electrode to the arc travel speed [4]. the welding speed has a major influence on the arc energy formed during co2-mag welding, since a high welding speed will provide a lower energy input per unit of length of a welded joint mailto:dr.salah2007@yahoo.com salah sabeeh abed-alkareem al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 6480(2014) 65 [5]. and, this will result in insufficient melting of the base metal. many researchers have been previously carried out by using co2-mag welding processes considering mainly the effect of process parameters on the structure and mechanical properties, but there is little works have focused on studying the influence of these parameters on the welding velocity and arc energy using the design of experiment (doe) and response surface methaolodgy (rsm) technique for modeling and optimization purposes for co2 mag welding [6-13]. therefore, the aim of this paper is to determine experimentally the effect of input parameters of this welding process on the welding velocity and arc energy. 2. experimental procedure 2.1. used material and samples preparation low carbon steel material type aisi 1010 in form of plate with 5 mm thickness in the hot rolled condition was used in this work to prepare samples for welding test. chemical analysis for this material was carried out, and the results are given in table 1. also, the mechanical properties of this steel were obtained by tensile test according to astm-e8 standard, and the resulted data are listed in table 2, presenting the average of three readings for three tested samples .samples were then prepared with dimensions of 50 mm× 25 mm×5 mm to be welded in a closed butt weld joint design by co2-mag process. table 1 and table 2 indicate that the used material matches to the standard base metal [14]. 2.2. used welding parameters the effective selected input factors of co2 mag welding in this work were welding speed, arc voltage and wire feed speed in two levels, as shown in table 3. these parameters were used based on the ability of welding machine and experimental skill of the welder operator. table 1, chemical composition of aisi 1010 the steel plate with standard type (wt%). table 2, mechanical properties for steel. elongation (%) tensile strength (mpa) yield strength (mpa) material 42 391 262 steel sample material c si mn p s cr mo used material 0.13 0.015 0.450 0.003 0.003 0.001 0.002 standard steel aisi 1010 [12] 0.08 – 0.13 0.1 max 0.3 0.6 0.04 max 0.05 max - - material ni al co cu v fe used material 0.043 0.036 0.007 0.001 0.001 bal. standard steel aisi 1010 [12] - - - - - bal. salah sabeeh abed-alkareem al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 6480(2014) 66 table 3, levels of input parameters used with respective coding. input parameter unit low level 1 high level + 1 -alpha +alpha voltage volt 19 21 18 22 wire feeding speed cm/min 125 175 100 200 gas flow rate l/min 8 12 5 14 2.3. welding test co2-mag welding tests were conducted for twenty samples using the welding factors mentioned above and depending on the design matrix established by design of experiment software, as given in table 4. these tests were achieved randomly to prevent any systematic error. the wire filler type ‘aws er70s-6’1.2 mm diameter in form of rod was used for welding samples. table 4, design matrix for input factors and experimental values of output (responses). std. no. run no. type of point voltage (volt) wire feed speed (cm/min) gas flow rate (l/min) welding velocity (mm/min) arc energy (joul/mm) 1 12 factorial 19 125 8 64.66 920 2 7 factorial 21 125 8 73.14 950 3 8 factorial 19 175 8 90 1640 4 1 factorial 21 175 8 105 1400 5 14 factorial 19 125 12 69.72 925 6 4 factorial 21 125 12 85.68 900 7 16 factorial 19 175 12 103.44 1380 8 18 factorial 21 175 12 114 1325 9 9 axial 18 150 10 66.66 1600 10 15 axial 22 150 10 85 1530 11 6 axial 20 100 10 65 230 12 2 axial 20 200 10 125 1180 13 19 axial 20 150 6 95.32 1050 14 10 axial 20 150 14 115 850 15 3 center 20 150 10 70 1750 16 11 center 20 150 10 75 1700 17 17 center 20 150 10 74.5 1690 18 5 center 20 150 10 71 1715 19 13 center 20 150 10 75.5 1800 20 20 center 20 150 10 73.8 1640 2.4. determination of welding velocity speed of welding is defined as the rate of travel of the electrode along the seam or the rate of travel of the work under the electrode along the seam. therefore, the welding speed during welding each sample was calculated using the following formula [15]: s = d t …(1) where, s = welding speed (mm/min). d = travel of electrode (mm). t = arc time (min). in the present, the travel of electrode (d) was first measured using a digital venire (with accuracy of 0.01mm). then, the arc time (t) was measured for the period between the start and end of achieving the welding pass using a stop watch. according to equation (1), the welding velocity (s) was calculated. salah sabeeh abed-alkareem al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 6480(2014) 67 2.5. determination of arc energy arc energy (heat input rate) is a relative measure of the energy transferred per unit length of weld. it is typically calculated as the ratio of the power (i.e., voltage, current) to the velocity of the heat source (i.e., the arc) as follows [16]. q = v∗i∗ 60 s … (2) where, q = arc energy (j/mm), v = arc voltage (volts) and i = welding current (ampere). for calculating the arc energy (q), the reading of both arc voltage (v) and welding current (i) were taken from the welding machine indicators during the welding process. then, using the calculated welding velocity (s) as mentioned in section (2.4), the arc energy (q) was obtained by equation (2).the results of measurements and calculations for these responses are also listed in table 4. 3. results and discussion 3.1. mathematical model of welding velocity for the welding velocity parameter, the analysis of variance (anova) was established by doe software as shown table 5. illustrating that the input parameters individually as well as the quadratic terms of voltage, wire feeding speed and gas flow rate are all statistically significant and have the greatest influence on the welding velocity response according to their p-values (< 0.05). the lack of fit test indicates a good model, since it is insignificant with p-value greater than 0.05. so, this analysis indicates that this model is significant at 95% confidence. in addition, this model showed a good agreement between the predicted and actual values for welding velocity, as shown in fig.1. therefore, the final predicted equation for the welding velocity in terms of the coded input factors is: welding velocity = +74.28 + 5.42 * a + 14.95 * b + 4.96 * c + 5.35 * b2 + 7.89 * c2 … (3) and , the final equation in terms of actual factors: welding velocity = + 241.40000 + 5.41750 * voltage 1.97110 * wire feeding speed 36.98125 * gas flow rate + 8.56400e-003 * wire feeding speed2 + 1.97313 * gas flow rate2 … (4) table 5, analysis of variance (anova) for response surface reduced quadratic model (welding velocity). source sum of squares df mean square f value p-value prob > f model 6508.89 5 1301.78 243.24 < 0.0001 significant a-voltage 469.59 1 469.59 87.74 < 0.0001 b-wire feeding speed 3577.24 1 3577.24 668.42 < 0.0001 c-gas flow rate 394.02 1 394.02 73.62 < 0.0001 b² 754.99 1 754.99 141.07 < 0.0001 c² 1641.57 1 1641.57 306.73 < 0.0001 residual 74.93 14 5.35 lack of fit 49.33 9 5.48 1.07 0.4970 not significant purr error 25.60 5 5.12 core total 6583.81 19 std. dev. = 2.31 r-squared = 0.9886 mean = 84.87 adj r-squared = 0.9846 c.v. % = 2.73 pred r-squared = 0.9792 press = 137.26 adeq precision = 50.037 salah sabeeh abed-alkareem al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 6480(2014) 68 fig. 1. predicted versus actual welding velocity data. the statistical properties of this model were diagnosed, and it was found that the residuals that falling on a straight line implying errors are normally distributed, as shown in fig.2. additionally, the residuals versus predicted actual for welding velocity data revealed no obvious pattern or unusual structure implying models are accurate as shown in fig.3. fig. 2. normal probability plot of residuals for welding velocity data. fig. 3. residuals versus predicted welding velocity data. design-expert® software welding velocity color points by value of welding velocity: 125 64.66 actual p r e d ic t e d predicted vs. actual 60.00 70.00 80.00 90.00 100.00 110.00 120.00 130.00 60.00 70.00 80.00 90.00 100.00 110.00 120.00 130.00 design-expert® software welding velocity color points by value of welding velocity: 125 64.66 internally studentized residuals n o r m a l % p r o b a b il it y normal plot of residuals -2.00 -1.00 0.00 1.00 2.00 1 5 10 20 30 50 70 80 90 95 99 design-expert® software welding velocity color points by value of welding velocity: 125 64.66 predicted i n t e r n a ll y s t u d e n t iz e d r e s id u a ls residuals vs. predicted -3.00 -2.00 -1.00 0.00 1.00 2.00 3.00 60.00 70.00 80.00 90.00 100.00 110.00 120.00 130.00 salah sabeeh abed-alkareem al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 6480(2014) 69 the perturbation of the predicted welding velocity response resulted by varying only one parameter at a time from the center point of the investigated region is shown in fig.4. it can be seen that increasing all the three input parameters generally increase the welding velocity, since these input parameters increased the fusion effect of the weld joint, which necessitates increasing the welding velocity to keep the stability of the welding process. fig. 4. perturbation of welding velocity on wire feeding speed and gas flow rate. due to no statistical problems found, the response surface plots were generated in terms of 2d surface plot as shown in figs.5-7 depicting the welding velocity as a function of voltage and wire feeding speed at various gas flow rates 8, 10 and 12 l/min, respectively. these figures indicate that both voltage and wire feeding speed have greater influence on increasing the welding velocity than the gas flow rate which has a slight effect. this is possibly due to increase of molten material accumulated in the weld joint caused by higher voltage and wire feeding speed. also, this is more likely ascribed to the increased chemical reaction of co2 with the accumulated molten material in the weld joint. fig. 5. contour graph of welding velocity as a function of voltage and wire feeding speed gas flow rate 8 l/min. design-expert® software factor coding: actual welding velocity actual factors a: voltage = 20 b: wire feeding speed = 150 c: gas flow rate = 10 perturbation deviation from reference point (coded units) w e ld in g v e lo c it y -1.000 -0.500 0.000 0.500 1.000 60 70 80 90 100 a a b b c c design-expert® software factor coding: actual welding velocity design points 125 64.66 x1 = a: voltage x2 = b: wire feeding speed actual factor c: gas flow rate = 10 19 20 20 21 21 125 135 145 155 165 175 welding velocity a: voltage b : w ir e f e e d in g s p e e d 60 65 70 75 80 85 90 95 6 salah sabeeh abed-alkareem al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 6480(2014) 70 fig. 6. contour graph of welding velocity as function of voltage and wire feeding speed gas flow rate 10 l/min. fig. 7. contour graph of welding velocity as a function of voltage and wire feeding speed gas flow rate 12 l/min. figures 8-10 show 3d surface plots for welding velocity as a function of voltage and wire feeding speed at different gas flow rates, showing similar behavior as mentioned above. eventually, these observations are confirmed by the cube plot for the welding velocity, as shown in fig. 11. fig. 8. 3d graph of welding velocity as a function of voltage and wire feeding speed at gas flow rate 8 l/min. design-expert® software factor coding: actual welding velocity design points 125 64.66 x1 = a: voltage x2 = b: wire feeding speed actual factor c: gas flow rate = 8 19 20 20 21 21 125 135 145 155 165 175 welding velocity a: voltage b : w ir e f e e d in g s p e e d 65 70 75 80 85 90 95 100 design-expert® software factor coding: actual welding velocity design points 125 64.66 x1 = a: voltage x2 = b: wire feeding speed actual factor c: gas flow rate = 12 19 20 20 21 21 125 135 145 155 165 175 welding velocity a: voltage b : w ir e f e e d in g s p e e d 75 80 85 90 95 100 105 110 design-expert® software factor coding: actual welding velocity 125 64.66 x1 = a: voltage x2 = b: wire feeding speed actual factor c: gas flow rate = 8 125 135 145 155 165 175 19 20 20 21 21 40 60 80 100 120 140 w e ld in g v e lo c it y a: voltage b: wire feeding speed salah sabeeh abed-alkareem al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 6480(2014) 71 fig. 9. 3d graph of welding velocity as a function of voltage and wire feeding speed at gas flow rate 10 l/min. fig. 10. 3d graph of welding velocity as a function of voltage and wire feeding speed at gas flow rate 12 l/min. fig. 11. cube shape of welding velocity. design-expert® software factor coding: actual welding velocity design points above predicted value design points below predicted value 125 64.66 x1 = a: voltage x2 = b: wire feeding speed actual factor c: gas flow rate = 10 125 135 145 155 165 175 19 20 20 21 21 40 60 80 100 120 140 w e ld in g v e lo c it y a: voltage b: wire feeding speed design-expert® software factor coding: actual welding velocity design points above predicted value design points below predicted value 125 64.66 x1 = a: voltage x2 = b: wire feeding speed actual factor c: gas flow rate = 12 125 135 145 155 165 175 19 20 20 21 21 40 60 80 100 120 140 w e ld in g v e lo c it y a: voltage b: wire feeding speed design-expert® software factor coding: actual welding velocity x1 = a: voltage x2 = b: wire feeding speed x3 = c: gas flow rate cube welding velocity a: voltage b : w ir e f e e d in g s p e e d c: gas flow rate a-: 19 a+: 21 b-: 125 b+: 175 c-: 8 c+: 12 62.0713 72.1688 92.1488 102.246 73.0788 83.1763 103.156 113.254 6 salah sabeeh abed-alkareem al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 6480(2014) 72 3.2. mathematical model of arc energy similarly, the analysis of variance (anova) for rsm reduced quadratic model was determined for the arc energy as given in table 6. the results in this table show that the wire feeding speed (b) and gas flow rate (c) are statistically significant, since their p-values were very small (< 0.5).while the voltage (a) has no influence on the weld joint. moreover, this table also indicate that the lack of fit was insignificant (p-value > 0.05), indicating that this model is adequate and significant at 95% confidence. so, the final predicted equation for the arc energy in terms of the coded input factors is: arc energy = + 1706.02 26.88 * a + 246.87 * b 48.75 * c 42.61 * a2 257.61 * b2 -196.36 * c2 … (5) and , the final equation in terms of actual factors is: arc energy = 30222.61364 +1677.67045 * voltage +133.52955 * wire feeding speed + 957.44318 * gas flow rate 42.61364 * voltage2 0.41218 * wire feeding speed2 49.09091 * gas flow rate2 … (6) table 6, analysis of variance (anova) for response surface reduced quadratic model (arc energy). source sum of squares df mean square f value p-value prob > f model 3.257e+006 6 5.428e+005 114.66 < 0.0001 significant a-voltage 11556.25 1 11556.25 2.44 0.1422 b-wire feeding speed 9.752e+005 1 9.752e+005 206.00 < 0.0001 c-gas flow rate 38025.00 1 38025.00 8.03 0.0141 a2 45657.47 1 45657.47 9.65 0.0084 b² 1.669e+006 1 1.669e+006 352.49 < 0.0001 residual 61538.07 13 4733.70 lack of fit 46617.23 8 5827.15 1.95 0.2390 not significant purr error 14920.83 5 2984.17 core total 3.318e+006 19 std. dev. = 68.80 r-squared = 0.9815 mean = 1308.75 adj r-squared = 0.9729 c.v. % = 5.26 pred r-squared = 0.9529 press = 1.563e+005 adeq precision = 37.446 the adequacy of this model was checked to examine the predicted model. two types of model diagnostics, the normal probability plot and residuals versus the actual values plot, were used for verification, as shown in figs. 12 and 13 for arc energy respectively. it can be observed from these plots that there was no violation of the normality assumption, since they normal probability plot followed a straight line pattern, the residual was normally distributed, and as long as the residuals versus the predicted values show no unusual pattern and no outliers. also, this model shows a good agreement between the predicted and actual values for arc energy, as depicted in fig. 14. salah sabeeh abed-alkareem al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 6480(2014) 73 fig. 12. normal probability plot of residuals for arc energy data. fig. 13. residuals versus predicted arc energy data. fig. 14. predicted versus actual arc energy data. the perturbation plot of the predicted responses caused by changing only one factor at a time from the center point of the experimental region is shown in fig. 15. this figure indicates that, individually, the wire feeding speed has greater effect than the gas flow rate on arc energy, design-expert® software arc energy color points by value of arc energy: 1800 230 internally studentized residuals n o r m a l % p r o b a b il it y normal plot of residuals -2.00 -1.00 0.00 1.00 2.00 1 5 10 20 30 50 70 80 90 95 99 design-expert® software arc energy color points by value of arc energy: 1800 230 predicted i n t e r n a ll y s t u d e n t iz e d r e s id u a ls residuals vs. predicted -3.00 -2.00 -1.00 0.00 1.00 2.00 3.00 0.00 500.00 1000.00 1500.00 2000.00 design-expert® software arc energy color points by value of arc energy: 1800 230 actual p r e d ic t e d predicted vs. actual 0.00 500.00 1000.00 1500.00 2000.00 0.00 500.00 1000.00 1500.00 2000.00 salah sabeeh abed-alkareem al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 6480(2014) 74 while the voltage is not influential. this is more probably because of the increasing wire feeding speed resulted in an increase in the welding velocity, leading to more accumulation of molten material due to more thermal effect and less chemical affinity of the co2 gas with the weld joint material. fig. 15. perturbation of arc energy on wire feeding speed and gas flow rate. because of no statistical problem with the model, fig. 16 shows the 2d contour plot for the arc energy as a function of voltage and wire feeding speed at gas flow rate of 10 l/min. whereas, figs. 17-19 depict 3d surface plots for the arc energy at gas flow rate of 8, 10 and 12 l/min, respectively. it can be noted from these figures that increasing both wire feeding speed and gas flow rate increases the arc energy due to the increase of quantity of the molten material that resulted by the increasing of the welding velocity and thermal input. finally, these observations are confirmed by the cube plot for arc energy, as shown in fig.20. fig. 16. contour graph of arc energy as a function of voltage and wire feeding speed at gas flow rate 8 l/min. design-expert® software factor coding: actual arc energy actual factors a: voltage = 20 b: wire feeding speed = 150 c: gas flow rate = 10 perturbation deviation from reference point (coded units) a r c e n e r g y -1.000 -0.500 0.000 0.500 1.000 1200 1300 1400 1500 1600 1700 1800 a a b b c c design-expert® software factor coding: actual arc energy design points 1800 230 x1 = a: voltage x2 = b: wire feeding speed actual factor c: gas flow rate = 10 19 20 20 21 21 125 135 145 155 165 175 arc energy a: voltage b : w ir e f e e d in g s p e e d 1200 1200 1300 1400 1500 1600 1700 1725 1650 1750 1765 6 salah sabeeh abed-alkareem al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 6480(2014) 75 fig. 17. 3d graph of arc energy as a function of voltage and wire feeding speed at speed at gas flow rate 10 l/min. fig. 18. 3d graph of arc energy as a function of voltage and wire feeding speed at gas flow rate 10 l/min. fig. 19. 3d graph of arc energy as a function of voltage and wire feeding speed at gas flow rate 12 l/min. design-expert® software factor coding: actual arc energy 1800 230 x1 = a: voltage x2 = b: wire feeding speed actual factor c: gas flow rate = 8 125 135 145 155 165 175 19 20 20 21 21 0 500 1000 1500 2000 a r c e n e r g y a: voltage b: wire feeding speed design-expert® software factor coding: actual arc energy design points above predicted value design points below predicted value 1800 230 x1 = a: voltage x2 = b: wire feeding speed actual factor c: gas flow rate = 10 125 135 145 155 165 175 19 20 20 21 21 0 500 1000 1500 2000 a r c e n e r g y a: voltage b: wire feeding speed design-expert® software factor coding: actual arc energy design points above predicted value design points below predicted value 1800 230 x1 = a: voltage x2 = b: wire feeding speed actual factor c: gas flow rate = 12 125 135 145 155 165 175 19 20 20 21 21 0 500 1000 1500 2000 a r c e n e r g y a: voltage b: wire feeding speed salah sabeeh abed-alkareem al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 6480(2014) 76 fig. 20. cube shape of arc energy. 3.3. numerical optimization the numerical optimization is provided by the design of experiment software to find out the optimum combinations of parameters in order to fulfill the requirements as desired. therefore, this software was used for optimizing the welding velocity and arc energy; based on the data from the predicted models as a function of three factors: arc voltage, wire feeding speed and gas flow rate. table 7 lists the constrains of each variable for numerical optimization of the welding velocity and arc energy. according to this table, one possible run fulfilled the specified constrains to obtain the optimum values for welding velocity, arc energy and desirability, as listed in table 8. it can be noted that this run gave a desirability of 0.849 with the optimum values of the voltage (20 volt), wire feeding speed (153 cm/min), gas flow rate (10 l/min), welding velocity (77.071 mm/min) and arc energy (1722 joule/mm). figures 21-23 show 3d surface plots for desirability, optimum value of welding velocity and optimum value of arc energy, respectively as a function of voltage and wire feeding speed at 10 l/min gas flow rate. table 7, constrains used for the numerical optimization. goal lower limit upper limit lower weight upper weight importance a:voltage is in range 19 21 1 1 3 b:wire feeding speed is in range 125 175 1 1 3 c:gas flow rate is in range 8 12 1 1 3 welding velocity minimize 64.66 125 1 1 3 arc energy maximize 230 1800 1 1 3 table 8, optimum solutions of the desirability. design-expert® software factor coding: actual arc energy x1 = a: voltage x2 = b: wire feeding speed x3 = c: gas flow rate cube arc energy a: voltage b : w ir e f e e d in g s p e e d c: gas flow rate a-: 19 a+: 21 b-: 125 b+: 175 c-: 8 c+: 12 1038 941 1532 1434 984 887 1478 1381 6 number voltage (volt) wire feeding speed (cm/min) gas flow rate (l/min) welding velocity (mm/min) arc energy (joul/mm) desirability 1 20 153 10 77.071 1722 0.849 selected salah sabeeh abed-alkareem al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 6480(2014) 77 fig. 21. 3d graph for desirability as a function of voltage and wire feeding speed at gas flow rate 10 l/min. fig. 22. the optimum value for welding velocity at 10 l/min gas flow rate. fig. 23.the optimum value for arc energy at 10l/min gas flow rate. design-expert® software factor coding: actual desirability 1.000 0.000 x1 = a: voltage x2 = b: wire feeding speed actual factor c: gas flow rate = 10 125 135 145 155 165 175 19 20 20 21 21 0.400 0.500 0.600 0.700 0.800 0.900 d e s i r a b i l i t y a: voltage b: wire feeding speed 0.8490.849 design-expert® software factor coding: actual welding velocity 125 64.66 x1 = a: voltage x2 = b: wire feeding speed actual factor c: gas flow rate = 10 125 135 145 155 165 175 19 20 20 21 21 50 60 70 80 90 100 w e l d i n g v e l o c i t y a: voltage b: wire feeding speed 77.040777.0407 design-expert® software factor coding: actual arc energy 1800 230 x1 = a: voltage x2 = b: wire feeding speed actual factor c: gas flow rate = 10 125 135 145 155 165 175 19 20 20 21 21 1100 1200 1300 1400 1500 1600 1700 1800 a r c e n e r g y a: voltage b: wire feeding speed 17221722 salah sabeeh abed-alkareem al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 6480(2014) 78 3.4. weld joint efficiency calculation: in order to obtain the efficiency of the weld joint obtained by co2-mag welding of low carbon steel aisi 1010, three tensile samples were first welded with the optimum welding condition given in table – and then tensile tested to determine the ultimate tensile strength of the weld joint. the average tensile strength was found to be 285 mpa. therefore, the efficiency of the weld joint was calculated to be 73% according to the joint efficiency definition which is the ratio of the tensile strength of the weld joint to the tensile strength of the base metal (table 2). this result indicates the importance of using co2-mag welding process and its effectiveness and suitability for welding steel aisi 1010 from strength point of view. 4. conclusions 1. regarding the welding velocity, a quadratic model was obtained by doe with rsm technique for the optimum welding velocity response in terms of input welding parameters. his model indicated that the arc voltage, wire feeding speed and gas flow rate largely effective on welding velocity. 2. concerning the arc energy, a quadratic model was obtained for the optimum arc energy response in terms of input welding parameters. this model shows that the wire feeding speed has greater impact than gas flow rate on arc energy, while the arc voltage was found not affected. 3. by numerical optimization, the optimum values of the voltage, wire feeding speed, gas flow rate, welding velocity, arc energy and desirability are (20volt),(153cm/min),(10l/min), (77.071mm/min) (1722 joule/mm ) and ( 0.849), respectively. 4. doe with rsm was found a useful tool for predicting the responses in mag-co2 welding technique for any given input parameters. 5. references [1] katokihiko, ikeda rinsei and yasuda koichi," development of ultra-low spatter co2 gas-shielded arc welding process", jfe giho, no. 16, p. 50–53, june 2007. [2] parth d. patel and sachin p patel,"prediction of weld strength of metal active gas (mag) welding using artificial neural network", international journal of engineering research and applications (ijera), issn: 2248-9622, vol. 1, issue 1, pp.036-044, 1-12014. [3] op khanna, "a text book of welding technology", dhanpat rai publications ltd., pp.351, 2006. [4] neeraj kumar sharma and kunal sharma, "to study the effect of process variable on properties of 2.25cr-1mo steel in gmaw", international journal of engineering research & technology (ijert), vol. 2, issue 5, issn: 2278-0181, may 2013. [5] miloš jovanovic , janez grum and miro uran 1," influence of lack-of-fusion defects on load capacity of mag welded joints", 17th world conference on nondestructive testing, shanghaichina , 25-28 oct 2008 . [6] v. gunaraj and n. murugan, " application of response surface methodology for predicting weld bead quality in saw of pipes", journal of mater processing technology, vol. 88, 266-275, 1999. [7] a. i. khuri and j. cornell," response surfaces design and analysis", 2nd ed, marcel dekker, new york, (1996). [8] gunaraj and n. murugan , " prediction and optimization of weld bead volume for the submerged arc process — part 1", welding research supplement, 286-s 294-s , october2000. [9] vinod kumar, " modeling of weld bead geometry and shape relationships in submerged arc welding using developed fluxes". jordan journal of mechanical and industrial engineering, volume 5, number 5, issn 1995-6665 pages 461 – 470, oct. 2011. [10] s. thiru chitrambalam, tan wee ming, imran syakir mohammad and shafizal bin mat , "a study on relationship between process variables and weld penetration for gas metal arc welding (gmaw)", international conference and exhibition on sustainable energy and advanced materials , solo-indonesia,p. 237, october 3-4, 2011. [11] nischal chhabra , nirmal s. kalsi and dilbag singh, " effect of shielding gases on micro hardness of fe 410 (aisi 1024) steel welded joint in gmaw process" , international journal on emerging technologies 5(1), issn no. (online): 22493255, 8-13(2014). salah sabeeh abed-alkareem al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 6480(2014) 79 [12] s. thiru chitrambalam, chew lai huat, phang boo onn, s.hemavathi, imran syakir mohammad and shafizal bin mat. "an investigation on relationship between process control parameters and weld penetration for robotic co2 arc welding using factorial design approach",the journal of mechanical engineering and technology, volume 4, pages 1-16.publisher university technical malaysia melaka, 2012. [13] edwin raja dhas j and jenkins hexley dhas s," a review on optimization of welding process". procedia engineering 38 (2012) 544 – 554 elsevier. [14] http://www.efunda.com/materials/alloys/carb on_steels/show_carbon.cfm?id=aisi_1010 &prop=all&page_title=aisi%201010. [15] jatinder gill and jagdev singh," efect of welding speed and heat input rateon stress concentration factor of butt welded joint of is 2062 e 250 a steel", international journal of advanced engineering research and studies, eissn2249–8974 ijaers/vol. i/ issue iii/april-june, 2012/98-100. [16] ajay n.boob and prof.g. k.gattani, " study on effect of manual metal arc welding process parameters on width of heat affected zone (haz) for ms 1005 steel", international journal of modern engineering research (ijmer), vol. 3, issue. 3, pp-14931500, issn: 2249-6645, may, june. 2013. http://www.efunda.com/materials/alloys/carbon_steels/show_carbon.cfm?id=aisi_1010&prop=all&page_title=aisi%201010 http://www.efunda.com/materials/alloys/carbon_steels/show_carbon.cfm?id=aisi_1010&prop=all&page_title=aisi%201010 http://www.efunda.com/materials/alloys/carbon_steels/show_carbon.cfm?id=aisi_1010&prop=all&page_title=aisi%201010 (2014)6480 ، صفحة4، العذد10دجلة الخىارزهي الهنذسية الوجلصالح صبيخ عبذ الكرين م 80 (mag)أيجاد سرعة اللحام وطاقة القىس لىصلة لحام القىس الوعذني االنصهاري صالح صبيخ عبذ الكرين جايعت بغذاد/ انضساعتكهٍت /لسى انًكائٍ واَالث انضساعٍت dr.salah2007@yahoo.com :االنكخشوًَ انبشٌذ الخالصة سبىٌ فً حضًٍ هزا انبحث دساست عًهٍت نغشض اٌجاد حأثٍشسشعت انهحاو وطالت انمىط انخً حخكىٌ نطشٌمت نحاو انمىط انًعذًَ بغاص ثاًَ أوكسٍذ انكاي وانخً حى دساسخها ( ص سشعت حغزٌت سهك انهحاو ويعذل جشٌاٌ انغا, فىنخٍت انمىط)أٌ انعىايم انذاخهت راث األهًٍت نهزِ انطشٌمت هً . بشكت انهحاو االَصهاسي حى اسخعًال حمٍُت حصًٍى انخجاسب يع طشٌمت االسخجابت انسطحٍت نبُاء يىدٌالث سٌاضٍت حخص سشعت انهحاو . ألٌجاد حأثٍشاحها عهى كفاءة انىصهت انًهحىيت ٌعٍت انخً حى انحصىل عهٍها وانخً حى انخُبأ بها لذ دلمج انًىدٌالث انشٌاضٍت انخشب" . وطالت انمىط نىصهت انهحاو بذالنت عىايم انهحاو انذاخهت وانًزكىسة آَفا أيثهٍت انخحهٍم انعذدي انخً حى انحصىل يٍ خالنها انى أدق انمٍى نسشعت فضال عٍ. وحممج أغشاضها بًىثىلٍت بعذ ححهٍهها بطشٌمت ححهٍم انخباٌٍ " أحصائٍا .ة يع انُخائج انخً حى انخُبأ بها يٍ جشاء هزا انبحث وجذث بأَها راث حطابك جٍذ حى يماسَت انُخائج انًسخحصم.انهحاو و طالت انمىط نىصهت انهحاو mailto:dr.salah2007@yahoo.comالبريد mailto:dr.salah2007@yahoo.comالبريد <4d6963726f736f667420576f7264202d20e3e5cfed20e6cee1dd20e6c7cde3cf20d1d4edcf35302d3537> al-khwarizmi engineering journal al-khwarizmi engineering journal,vol. 13, no. 4, p.p. 5057 (2017) wireless network control system for electro stati precipitator in cement plants mehdi j. marie* khalaf s. gaied** ahmed r. ajel*** *al-zawraa state company/ ministry of industry and minerals/ iraq **college of engineering/ tikrit university/ iraq ***institute of technology/ baghdad/ iraq *email: mehdijelo@gmail.com **email: gaeid khalaf@gmail.com ***email: drahmed69@gmail.com (received 8 september 2016; accepted 26 april 2017) https://doi.org/10.22153/kej.2017.04.003 abstract wireless control networks (wcns), based on distributed control systems of wireless sensor and actuator networks, integrate four technologies: control, computer network and wireless communications. electrostatic precipitator (esp) in cement plants reduces the emissions from rotary kiln by 99.8% approximately. it is an important thing to change the existing systems (wireline) to wireless because of dusty and hazardous environments. in this paper, we designed a wireless control system for esp using truetime 2 beta 6 simulator, depending on the mathematical model that have been built using identification toolbox of matlab v7.1.1. we also study the effect ofusing wireless network on performance and stability of the closed loop control system. simulation results of wcn for esp show smooth operation with a little bit of perturbation between transient and steady state region. keywords: distributed control systems, ieee802.15.4 protocol, wireless control networks (wcns), wireless sensor networks. 1. introduction wireless network control systems has very broad application prospects in the military, industry, urban management, environmental monitoring, and many other important areas which have potential practical values.the electrostatic precipitator (esp) is a filtration device that removes fine particles, such as dust and smoke from the gas stream using the power of the electric charges and electrostatic principles [1]. the cement plants are considered as hazardous places that contain a lot of dangerous materials and emits a huge quantities of air pollutants such as cox, nox, sox, and dust. these materials cause a lot of diseases and affect the sanitary in general. there are many methods by which they treat these emissions, such as bag falters, wet scrubbers and dust filters (esps) as shown in fig.1. the esp efficiency is approximately 99.8% which is the best one between other types [2]. the motivation of this paper is “to participate the efforts to refurbish the iraqi cement” plants because they have been installed since the eighties of the last century. also it is required to build a new monitoring pollution system by environmental agencies. the use of the wireless sensor network and wcns will serve to monitor and control the pollution inside and outside the plant. the overall system of esp consists of three main units: power supply, rappers, heaters. the mechanical iron structure is shown in fig.2. the mehdi j. marie al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 5057 (2017) 51 esp uses a technology that depends on a negative high voltage direct current power supply ( hvdcps). the power supply consists of two main units: transformer-rectifier (tr) set and controller cabinet. the tr set is used to step up the low voltage to high while the bridge rectifier is used to change the ac voltage to dc with negative polarity. the tr set also sends the current and the voltage values to the controller to make decisions about the control signal triggers which then sent to the actuator (thyristor unit). the control strategy is the wellknown pid controller. the -hvdcps is used to supply the energy to form the corona which is used to charge the contents of the drain fluid from the smoke chamber of the rotary kiln. fig. 1. general layout of the cement plant [1]. according to [3], the best way to understand the principle of operation is through the following activities: 1. ionization: charging of particles. 2. migration: transporting the charged particles to the collecting surfaces. 3. collection: precipitation of the charged particles on to the collecting surfaces. 4. charge dissipation: neutralizing the charged particles on the collecting surfaces. 5. particle dislodging: removing the particles from the collecting surface to the hopper. 6. particle removal: conveying the particles from the hopper to a disposal point. fig.2. esp mechanical structure [3]. 2. related works the following papers are surveyed to start the work of designing the wcn for esp in cement plants: victor and anders [4] proposed an expert system based fuzzy logic control system. they implemented an on-line control for esp used in coal fired boilers. kawka et al. [5] analysed a simple communication system and the probability of a two-state markov network model. the impact on the stability-performance of data loss and the wireless network system. sun and el-farra [6] developed integrated model-based networked control and scheduling for plants with distributed control system having an interconnected unit framework. they used the resource constraints, to exchange the information by wireless sensor network (wsn). pajic et al. [7] presented a method of stabilizing the plant resources of a network having limited wireless node. the dedicated controller node, only to face the routing information in traditional networked control system, their approach treats the network itself as the controller. design and experimental validation of model predictive control (mpc) of a hybrid dynamical laboratory process with wireless sensors is presented by bemporad et al. [8]. the laboratory process consists of four infrared lamps, controlled in pairs by two on/off switches, and of a transport mehdi j. marie al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 5057 (2017) 52 belt, where moving parts equipped with wireless sensors. kurt huang [9] introduced investigations results and solutions for spark problems in esps. a spark control strategy was proposed to overcome this problem in dry process units. wei zeng et al. [10] proposed a measurement architecture using distributed air sniffers, which provides convenient delay measurement, and requires no clock synchronization or instrumentation at the wireless sensor nodes. one challenge in deploying this architecture is how to place the sniffers for efficient network with delays in measurements. feng and wencai [11] addressed time-variant and uncertain network delay in the wireless networked control systems (wncs), as well as smith predictor model where real model of the controlled plant might be mismatched. 3. mathematical model of esp the esps are distinguished for two different types of processes according to [12], these are wet and dry. the esp is a large mechanical structure (as shown previously in fig. 2) designed and manufactured in a special way. it consists mainly of discharge electrodes (some times called wires) and collecting plates. the plates are fixed in vertical parallel manner to forming gas passages of 30-40cm apart. discharge electrodes are electrically isolated from plates and suspended in rows between the gas passages as shown in fig.3. both are fixed on mechanical frames and housed with an iron container. the hall structured is isolated from environment by glass wool. a high voltage system provides corona power to discharge electrodes to generate the electrostatic field. the particulate entrained in the gas, is charged while passing through the charged space. the gas stream which contains dust, fumes and different gases receives a negative charge.the dust particles and the gases are then deposited on the plates; which is connected to the ground; forming a dust layer on the collecting plates inside the esp. periodic rapping separates the accumulated dust layer from electrodes and plates. fig. 3. esp electrodes and plates structure. the mathematical model of esp is built depending on the input and the output data to the system. the input is the triggering gate to the thyristor unit while the output is the value of the dc voltage in kilo volt (kv) from the hvdcps. the data is then fed to the identification toolbox of matlab to find the contineous mathematical model. according to [13], the electrical operating points of esp are voltage (kv) and current (ma). “the value of corona depends on these electrical operating points. therefore, the whole process of an esp is mainly depends on the applied voltage and current. the relation to corona discharge is [2] )(* vcvai −= … (1) where a is a constant, vc is the corona starting voltage, i is the electric current and v is the applied voltage. at an electrode separation (d > 5 cm), the starting voltage of negative corona is (15*d kv) where d is the separation between the electrodes in cm.” as demonstrated in [14], this corona production field is determined experimentally, then the relationship between electric field and corona effect is represented by ])(0301.01[10126.3 5.06 w r rc r d de +×= …(2) where ec, dr, rw is “the corona onset field at the wire surface (v/m), the relative gas density and the radius of the wire (m) respectively. under the wire and direct plate, the maximum current density is given by )( 3 2 l v j o µε= …(3) where j, µ, v, l is maximum current density (a/m2), the ion mobility (m2 /vs), applied voltage and the shortest distance from the wire to collecting plate respectively. the value of the field when sparking is going to start is given by this relation mehdi j. marie al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 5057 (2017) 53 65.15 )273(103.6 p t es ×= …(4) where es, t, p is sparking field strength (v/m), absolute temperature (k), the gas pressure (atm) respectively and aesp collection efficiency (η) is )exp(1 feωη −−= …(5) and hence, )/exp(1 qaeωη −−= …(6) where ωe, f, a, q is the migration velocity (m/s), the specific collection area, the area of the collecting electrode” (m2 ), the gas flow rate (m3/s) respectively.the following relationship with voltage and current effects on the collection efficiency can be formulated as iv n=η …(7) this relation is useful for industrial applications of esps where n value is 2. working at maximum available voltage and improve collection performance of esp. the electric field due to positive line charge (e1) and negative line charge (e2) can make the total potential due to both values of the electric fields is [15]-[16] )( 21 eee −= …(8) the electric field can be also given by )ln( 2 * 22 1 22 1 ar br l e o + + = πε ρ …(9) where ρ, εo, r1, b and a are space permeability,permittivity, distance from point p depending on the geometrical plane shown in fig. 4. the mirror image of both wire and infinite plane of coolecting electrode are used to analyse the electric field inside the esp. the four general steps in esp process which depends on electric field charge are as follows [3]: 1. locate the charge to collect particles. 2. collector into a particle. 3. collectors will neutralize the charge. 4. remove the collected particle. fig. 4. mirror image of a wire and infinite plane. the transfer function of the esp can be obtained as follows : to model the dynamics between input and those of the final output, an industrial experiment has been carried out. during stable operation of the plant, the inlet flow was reduced to 1% for one hour. the flow was then increased to 8%, and simultaneously, high frequency sampling started in the final product stream. sampling lasted one hour. thus, the step response of the system had been determined. a first order dynamics with time delay is described by (10), the steady state minimum and maximum values of operation operating points, l and τ, the delay time and first order time constant, respectively. the unknown parameters had been identified using newton-raphson non-linear regression. the operating point was represented by minimum and maximum values as minop and maxop. their values are the following: minop = 1 %, maxop = 4.5 %, l = 0.9 min, τ = 11.8 sec. the transfer function of the esp can be obtained from the step response of the operation principle of the given system under two cases: 1. normal operation as shown in fig.5, where operation means the output voltage of the system. 2. system with decreased rise time as in fig.6. fig. 5. the normal operation of the esp cement plant. increasing the speed of operation will lead to increase the overshoot by approximately 5% which should be reduced during the controller design as shown in in fig.6. 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.8 0.9 0 1 2 3 4 5 6 time(hour) o p er a ti o n mehdi j. marie al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 5057 (2017) 54 fig. 6. increasing the speed of response for operation. the parameters of the process model ( first-order plus dead-time) assumes [17], that is lse s k sg − + = 1 )( τ …(10) se s sg 9.0 18.11 5.4)( − + = …(11) where k is the process gain. the output equation for step input of the excitation amplitude approximation is given by )(exp1)( lt lt katc − − −−=                             τ …(12) rise in the index of the steady state level of the ka, which at the start with the slope of the initial rise of tangent 1:00 constant τ after the steady state level is reached to c(t) in eq.(12). further, increase time constant of the exponential is one after reaching 63% of the final value. therefore, parameter estimation based on step response of a process using a tangent line approximation. adjusting rules used to determine the value of pid controller parameters. the most popular tuning rules due to the ziegler-nichols first method. the pid controller design parameter for this operation kp=3.147, ti = 18, td = 4.5, hence the best parameters of pid controller transfer function needed for best operation is [17] )11()( st st ksc d i ppid ++= …(13) )5.4 18 11(147.3)( s s scpid ++= …(14) s ss scpid 18 11881147.3)( 2 ++ = …(15) the closed-loop transfer function of over all system can be formulated as se ss ss st 9.0 184.212 16.149.2541147)( 2 2 − + ++ = …(16) the bode plot of the designed and simulated system is shown in fig.7. as illustrated in this figure, the closed loop system is stable and the performance is acceptable. fig. 7. bode plot of the designed system. 4. simulation results of wcn the ieee 802.15 standard protocol scheme is to support the short distances. “it offers two versions, high rate wireless personal area network wpan (802.15.3) supports high data rate and quality-of-service (qos) constraints for multimedia applications and suitable for ad-hoc mode”. low-cost, low power low rate wpan (802.15.4) data transfer rate and a relaxed performance requirements are available in ad-hoc mode, supported data speed is 250, 40, and 20 kbps [18].the schematic representation of the wireless closed-loop control system is shown in fig. 8. the wireless network uses either zigbee or wi-fi protocols in the simulation. fig. 8. block diagram of wcn. 5 10 15 20 25 30 35 40 45 50 55 60 0 1 2 3 4 5 6 time(min) o p er a ti o n 0 500 1000 1500 2000 2500 m a g n it u d e ( a b s ) 10 -6 10 -5 10 -4 10 -3 10 -2 10 -1 10 0 -1000 -800 -600 -400 -200 0 p h a s e ( ra d ) bode diagram frequency (rad/millisecond) mehdi j. marie al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 5057 (2017) 55 a wireless technology used for control systems often provides a range of meters to few kilometres. automation of these applications depends on requirements of range, for example, plant compared with relatively low process automation requirements of wireless coverage [19]. simulation results have been done using truetime 2 beta 6 simulator [20], [21] with the proposed block diagram as shown in fig.9. fig. 9. the wcn scheme for esp using truetime. the stability of the operation ensures the effectiveness of designing the controller as illustrated in fig. 10. fig.10. stability analysis of the wcn system. this figure can cope with the step response of the plant after 25 min delay in the operation shown in fig.11. fig. 11. step response of the designed system. the 85% duty cycle control is obtained with the operation of the system during the transient region (0-10) min as shown in fig.12. fig. 12. duty cycle control of esp power supply. during this period of operation the electrostatic voltage is increased from (0-24) kv in the first 4 min and increased to the nominal 60 kv after 10 min as shown in fig.13. both fig.12. and fig.13 shows smooth operation with a little bit of perturbation between transient and steady state region. fig. 13. output data from the designed system. 5 10 15 20 30 210 60 240 90 270 120 300 150 330 180 0 0 5 10 15 20 25 30 35 40 45 50 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 time(min) o p er a ti o n input(u) outpt(y) 0 10 20 30 40 50 60 70 0 15 25 35 45 55 65 75 85 time(min) d u ty c y cl e( p w m )% 0 10 20 30 40 50 60 0 10 20 30 40 50 60 70 time (min) v o lt a g e (k v ) mehdi j. marie al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 5057 (2017) 56 5. conclusions this paper proposed a wcn for eps in cement plants based on a robust wireless network. during the simulation with truetime software, one can monitor and control the esp activities wirelessly. wireless closed-loop control systems are suited to the environment of our dusty weather which is always have a lot of pollutants, so maintenance is very difficult, wireless network is becoming a strong competition against the wire network. wi-fi and zigbee protocols are good choice for short distances, low-rate and real-time control system, with its low-power, low-cost and low latency. the simulation shows that both of them can be used to form wireless network measurement and control system. 6. references [1] neundorfer company, “electrostatic precipitatorknowledgebase lessons”, retrieved october,2010. http://www.neundorfer.com/knowledge_base [2] james h. turner, gray p. grenier, william m. vatuvak “electrostatic precipitator” chapter 6, december 1995. [3] parker k. “ electrical operation of electrostatic precipitator” 2nd edition, 2007. [4] victor r. and anders ” on-line precipitator control with an expert system” in proceedings of icesp, korea, sept., 1998. [5] kawka p. and alleyne a. “stability and feedback control of wireless networked systems ” american control conference, 2005. [6] sun y. and el-farra n. ”resource aware quasidecentralized control of networked process systems over wireless sensor networks” chemical engineering science vol. 69, iss. , 2012. [7] pajic m., sundaram s., pappas g. and mangharam r.” the wireless control network: a new approach for control over networks” ieee transactions on automatic control, vol. 56, iss. 10, 2011. [8] bemporad, alberto di cairano, stefano henriksson, erik johansson, karl henrik ”hybrid model predictive control based on wireless sensor feedback: an experimental study” international journal of robust and nonlinear control, vol. 20, iss. 2, 2010. [9] kurt huang ” spark and its effects on esp ” in icespx, australia, 2006. [10] wei zeng, xian chen, yoo-ah kim and zhengming bu “delay monitoring for wireless sensor networks: an architecture using air sniffers ” 2010. [11] feng du and wencai du ” fuzzy immune control and new smith predictor for wireless networked control systems” chinese control and decision conference, 2009. [12] muhammad ahmad and jhanzeb. “modeling and simulation of an electrostatic precipitator” master thesis in electrical engineering, linnaeus university school of computer science ,physics and mathematics, sweden, 2011. [13] mizuno a. “electrostatic precipitation” ieee transactions on dielectrics and electrical insulation, vol. 7, no. 5, october, 2000. [14] sabah o. hamad "removal of cement dust from air by electrostatic precipitator", m. sc. thesis, university of baghdad, feb., 2005. [15] david k. cheng “field and wave electromagnetics”, 2nd edition, 1998. [16] astrom k. and hagglund t. “advanced pid controllers”, isa press, research triangle park, 2006. [17] nastasi c., pagano p., marinoni m. and lipari g. ” model based real-time networked applications for wireless sensor networks” ieee international conference on pervasive computing and communications, 2009. [18] pellegrini f., miorandi d., vitturi s., and zanella a. "on the use of wireless networks at low level of factory automation systems" ieee transactions on industrial informatics, vol.2, no.2, 2006. [19] henriksson d., cervin a., ohlin m. and karlerik årzén “truetime: real-time control system simulation with matlab/simulink,” department of automatic control, lund university, 2006. [20] khalaf s. gaied, ziad h. salih, mehdi j. marie, dr.ahmed r. ajel,” nonlinear compensation empyoing matrix converter with dtc controller “ international journal of innovative technology and exploring engineering (ijitee) issn: 2278-3075, volume-6 issue-4, september 2016 )2017( 50-57، صفحة4د، العد13دجلة الخوارزمي الهندسية المجلم مهدي جلو مرعي 57 في معامل السمنتالمستخدمة ةالكهروستاتيكي ةللمرسب ةالالسلكي ةالسيطرشبكة منظومة ***لاجاحمد رشيد ع **خلف سلوم كعيد *مهدي جلو مرعي العراق/ وزارة الصناعة والمعادن / شركة الزوراء العامة * العراق/ جامعة تكريت كلية الهندسة/ ** العراق بغداد/ -التكنولوجيامعهد *** mehdijelo@gmail.com: البريد االلكتروني* gaiedkhalaf@gmail.com: البريد االلكتروني ** drahmed69@gmail.com: البريد االلكتروني *** الخالصة انظمة السيطرة من تقريبا ومن المهم تغير % ٩٩٫٨يعمل المرسب الكهروستايتيكي في مصانع السمنت على تقليل االنبعاثات من الفرن الدوار بنسبة المتربة والخطرة. الى الشبكات الالسلكية بسبب البيئةاالنظمة الحالية (السلكية) ريق ط في هذا البحث استخدمنا شبكات التحكم الالسلكي والتي تسيطر على انظمة التحكم من خالل اجهزة االستشعار الالسلكية وشبكات المحركات عن هكذا عملية ب دمج عدة طرق تكنولوجية مثل السيطرة عن بعد واستخدام شبكة الكومبيوتر واالتصاالت الالسلكية, كما قمنا بتصميم النموذج الرياضي الخاص المحاكاة ل...كما درسنا تاثير استخدام الشبكة الالسلكية على اداء واستقرار نظام التحكم في الحلقة المغلقة. واظهرت النتائج من قبباستخدام البرنامج ماتالب عابرة ومنطقة ثابتة. من االضطراب بين منطقة سالسة االداء مع قليل امل ومحمد وسارة2 al-khwarizmi engineering journal, vol. 10, no. 2, p.p. corrosion control of buried low carbon steel structure alteration medias method amel s. merzah* mohammed h. *, *** technical college ** department of petroleum technology / university of technology *email: **email: ***email: (received 1 september abstract the aim of the present work is to control of metal buried corrosion by alteration the depended on the characteristics of each media. the corrosion rates in different media (soil, sand, porcelanite stone and gravel) for specimens of low carbon steel were measured by two methods weight loss method and polarization m weight loss measured by buried specimens in these medias separately for 90 days. the polarization method includes preparing of specimen and salt solutions have electrical resistivity equivalent electrical resistivity of these media. the corrosion rate of two method results in (soil > sand> porcelainte stone> gravel). the lower corrosion rate happened in gravel media because of characteristics of high electrical resistivity and lower porosity for gravel while the higher corrosion rate occurred in the soil. keywords: low carbon steel, corrosion rate, medias, electrical resistivity, soil, sand, porcelanite media, gravel. 1. introduction the study of soil as a corrosive medium is important taking into account the large amount of buried structures .the deterioration of that kind of structures could represent economic, safety, and environmental problems through the years. defined is an aggregate of minerals, organic matter, water, and gases (mostly air). it is formed by the combined weathering action of wind and water, and also organic decay [1]. then the corrosion process of buried metal structure is extremely variable and can range from rapid to negligible [2]. the corrosiveness of the soil can be defined as the capacity of producing and developing the corrosion phenomenon. soil is defined as an electrolyte and can be studied by electrochemical methods [3]. the factors ef of corrosive in soil included: khwarizmi engineering journal, vol. 10, no. 2, p.p. 6574 (2014) corrosion control of buried low carbon steel structure by alteration medias method mohammed h. hafiz** sarah k. mohammed *, *** technical collegebaghdad petroleum technology / university of technology email:amelmerza@yahoo.com email:drmhh1962@gmail.com ***email: sarah_materials@yahoo.com 1 september 2013; accepted 15 april 2014) the aim of the present work is to control of metal buried corrosion by alteration the media method. this method depended on the characteristics of each media. the corrosion rates in different media (soil, sand, porcelanite stone and gravel) for specimens of low carbon steel were measured by two methods weight loss method and polarization m weight loss measured by buried specimens in these medias separately for 90 days. the polarization method includes preparing of specimen and salt solutions have electrical resistivity equivalent electrical resistivity of these media. the te of two method results in (soil > sand> porcelainte stone> gravel). the lower corrosion rate happened in gravel media because of characteristics of high electrical resistivity and lower porosity for gravel while the higher low carbon steel, corrosion rate, medias, electrical resistivity, soil, sand, porcelanite media, gravel. the study of soil as a corrosive medium is large amount of buried structures .the deterioration of that kind of structures could represent economic, safety, and environmental problems through the years. soil as defined is an aggregate of minerals, organic matter, water, and gases (mostly air). it is formed by the combined weathering action of wind and water, and also organic decay [1]. then the corrosion process of buried metal structure is d can range from rapid to negligible [2]. the corrosiveness of the soil can be defined as the capacity of producing and developing the corrosion phenomenon. soil is defined as an electrolyte and can be studied by electrochemical methods [3]. the factors effects • electrical resistivity • porosity • dissolved salts including depolarizes or inhibitors • moisture • ph. each of these variables may affect the anodic and cathodic polarization characteristics of a metal in a soil [4]. soil electrical resistivity is an important parameter in underground corrosion general, the lower the resistivity, the higher the corrosion rate as shown in (table 1) al-khwarizmi engineering journal by using mohammed*** media method. this method depended on the characteristics of each media. the corrosion rates in different media (soil, sand, porcelanite stone and gravel) for specimens of low carbon steel were measured by two methods weight loss method and polarization method, weight loss measured by buried specimens in these medias separately for 90 days. the polarization method includes preparing of specimen and salt solutions have electrical resistivity equivalent electrical resistivity of these media. the te of two method results in (soil > sand> porcelainte stone> gravel). the lower corrosion rate happened in gravel media because of characteristics of high electrical resistivity and lower porosity for gravel while the higher low carbon steel, corrosion rate, medias, electrical resistivity, soil, sand, porcelanite media, gravel. dissolved salts including depolarizes or each of these variables may affect the anodic and cathodic polarization characteristics of a . soil electrical resistivity is an important parameter in underground corrosion in general, the lower the resistivity, the higher the corrosion rate as shown in (table 1). mailto:amelmerza@yahoo.com mailto:drmhh1962@gmail.com mailto:sarah_materials@yahoo.com amel s. merzah al-khwarizmi engineering journal, vol. 10, no. 2, p.p. 6473 (2014) 66 table1, corrosivity rating based on soil resistivity [1]. soil resistivity ω.cm corrosion rating >20,000 10,000-20,000 5000-10,000 3000-5000 1000-3000 <1000 essentially noncorrosive mildly corrosive moderately corrosive corrosive high corrosive extremely corrosive ions from dissolved salts and minerals must migrate through the electrolyte in a soil to supply the metal surface with the electron donors or acceptors necessary for the corrosion reaction to proceed. soil resistivity is a measure of the concentration of these ions and how easily they move through the soil environment [6]. metals buried in low resistivity soils will generally be anodic, whereas metals buried in adjacent high resistivity soils will generally be cathode .while the completely free of water has an extremely high resistivity. for example, sandy soils that easily drain water away are typically noncorrosive; clayey soils that hold water have low resistivity and are typically corrosive. alteration soil one method of corrosion control soil high in organic acids can be made less corrosive by surrounding the metal structure with limestone chips. a layer of chalk (caco3) surrounding buried pipes has been used in some soil formations likely to produce microbiologically influenced corrosion [4]. the resistivity indicates the probable corrosivity of the soil decreases with increasing water contents ions, thus nonporous soils. exhibit relatively high value of resistance, since the water content is small; these include nearly all of the igneous and metamorphic rocks such as granite, plus much sedimentary rock such as dense limestone or sandstone. the resistivity of bedrock can vary considerably depending upon the type of bedrock and extent of weathering and fracturing .the resistivity of the sand and gravel deposits generally high and uniform, while many bedrock formations have high but erratic resistivity or in the other word clay soils and shale layers generally have low resistivity values resulting from their inherent moisture and mineral content. very dry sand, gravel or rock has a very high resistance. as empty pore space fills the water, resistivity decreases. materials that lack pore space such as massive limestone, granite, and basalt have high resistivity. all other factors being constant, the degree to which crack and fissure are present controls the resistivity of rock [2].in (table 2) typical resistivity values minerals and soils are given. 2. experimental work corrosion rate was measured for specimen of low carbon steel in four different media (soil, sand, porcelanite stone and gravel). (table 3) shows the chemical composition of the low carbon steel. the specimen prepared for corrosion and microstructure test included grinding, polishing, etching and examination processes. (fig. 1) shows the microstructure of low carbon steel before it was buried in different media. methods of measuring the corrosion rate: 1. weight loss: in these method specimens was buried in (soil, sand, porcelanite stone and gravel) separately for 90days. the corrosion rate (cr), was calculated using the following formula: cr= δ w/ at …(1) cr: corrosion rate in mdd. δ w: weight loss in milligrams. a: exposed surface area in dcm2. t: time exposure in days. the conversion of corrosion rate in units milepenetration per years (mpy) by following relationship [7]: c.r (mpy) =(1.44/s.g)c.r (mdd) …(2) where: mpy: corrosion rate unit (mils penetration per year ) s.g: specific density of metal (for steel =7. 9 mg/cm3). 2. electrochemical techniques called polarization method this method is carried and consisting with an instrument of an electrochemical cell. the electrochemical cell contain three electrodes immersed in the solution ,working electrode (we) which represents the studied sample ,reference electrode (calomel) and an auxiliary (platinum) electrode, the cell is connected to a device ,which allows the changing in current range and measuring the output potential as a function of current ,at which the input and output data are controlled by computer program .the applied current is a linear function potential. amel s. merzah al-khwarizmi engineering journal, vol. 10, no. 2, p.p. 6473 (2014) 67 the corrosion of metal in soil depends upon its resistivity. electrochemical polarization methods are used for measuring corrosion rate using three solutions of resistivity of (20, 10000, 20000) ω.cm, (20ω.cm) for soil measurement by use device (soil box resistivity and det5/4d megger digital earth tester) shown in (fig. 2), (10000ω.cm) for sand and porcelanite, and 20000 for gravel [2], table (4) represents the equivalent values of the resistivity of this media depending on the standard value with varying the concentration of nacl as shown in (table 4) .the electrical conductivity of the solution was measured using digital electrical conductivity meter model (dds307) which is shown in (fig. 3). table 2, electrical resistivity of various minerals and soil [2]. minerals and soil resistivity , ω.cm minerals pyrite magnetite graphite rock salt(impure) serpentine igneoue rock granite diorite gabbro diabase metamorphic rocks garnet gneiss mica chist biotite gneiss slate sedimentary rock chattanooga shale michingan shale calumet and hecla conglomerates muschelkalk sandstone ferruginous sandstone muschelkalk limestone marl glacial till type of soil sand oil sand gravel loam clay silt 0.1 0.6-1.0 0.03 3000-500 000 20 000 500 000-100 000 1 000 000 10 000 000-1 400 000 000 310 000 20 000 000 130 000 100 000 000 -600 000 000 64 000 -6 500 000 2000-130 000 200 000 200 000-1 300 000 7000 18 000 18 000 7000 50 000 10 000500 000 400 – 22 000 20 000 – 400 000 300020 000 500 -2000 1000 -2000 table 3, the chemical composition of the specimen. alloy % c si mn fe component 0.16 0.15 0.7 reme. amel s. merzah al-khwarizmi engineeri table 4, equivalence of resistivity by nacl concentration nacl content g\l concentration % .30 3 0.04 0.004 0.0187 0.00187 fig.1. the microstructure of surface of low carbon steel specimen before it was buried in different media (200x). fig. 2. devices connected and the experiment of electrical resistivity measurement fig.3. digital electrical conductivity meter khwarizmi engineering journal, vol. 10, no. 2, p.p. 68 equivalence of resistivity by nacl concentration. resistivity ω.cm conductivity (µ 20 50 000 10000 100 20000 50 microstructure of surface of low carbon steel specimen before it was buried in different media devices connected and the experiment of electrical resistivity measurement . electrical conductivity meter. ng journal, vol. 10, no. 2, p.p. 6473 (2014) conductivity (µω/cm) microstructure of surface of low carbon steel specimen before it was buried in different media devices connected and the experiment of electrical resistivity measurement. amel s. merzah al-khwarizmi engineering journal, vol. 10, no. 2, p.p. 6473 (2014) 69 fig.4. shows corrosion rates of low carbon steel in different media the buried for 90 days. table 5, corrosion rates (mdd) and (mpy) for low carbon steel specimen at different medias. media corrosion rate (mdd) corrosion rate (mpy) soil 18.93628 3.4516 sand 2.6717933 0.4870 porcelanite stone 0.516 0.094055 gravel 0.2231 0.040666 table 6, the corrosion rate of specimen of low carbon steel by polarization method. resistivity (ω. cm) corrosion potential ecorr (mv) corrosion current density icorr (µa/cm2) corrosion rate (mpy ) 20 -450.1 199.21 83.592 10000 -330.9 14.38 6.03413 20000 -268 13.16 5.522 amel s. merzah al-khwarizmi engineering journal, vol. 10, no. 2, p.p. 6473 (2014) 70 fig. 5. (a1, a2), (b1, b2), (c1, c2)and (d1, d2) photographs and the microstructure of the surface specimens buried in soil, sand, porcelanite and gravel respectively (200x). b1 a1 a2 b2 c2 d1 c1 d2 amel s. merzah al-khwarizmi engineering journal, vol. 10, no. 2, p.p. 6574 (2014) 71 fig. 6. polarization curve of specimen of low carbon test in solution with electrical resistivity (20 ω. cm). fig.7. polarization curve for specimen of low carbon steel in solution with electrical resistivity (10000 ω. cm). fig.8. polarization curve for specimen of low carbon steel in solution with electrical resistivity (20000 ω. cm). amel s. merzah al-khwarizmi engineering journal, vol. 10, no. 2, p.p. 6574 (2014) 72 fig.9. the relationship between corrosion rate and current density. 3. results and discussion ( fig .4 ) and (table 5) represents the corrosion rate of low carbon steel specimens in different media (soil ,sand ,porcelanite stone and gravel) calculated by weight loss (first method) , specimens buried in this media for 90 days. note that the corrosion rates in (soil> sand >porcelanite stone> gravel), are the highest corrosion rates occurring in the soil and the less the corrosion rate occur in gravel because the highest electrical resistivity. (fig.5) shows the photographs and the microstructure of the surface of low carbon steel specimens after buried in different media. so the corrosion on surface of specimen buried in soil and sand can be observed, the corrosion product seen here is rust, surface color was dark orange to brown. those areas that are dark in color contain significant sediment on the surface as shown in (fig. 5) at (a 1, a2) and (b1, b2).the corrosion product on surface of specimen buried in porcelanite stone and gravel show very low , surface color ranging light orange to dark orange, and the rust is not uniform as shown in figure (5) at (c1,c2)and (d1,d2). calculation of corrosion rates by the second method (polarization method) using three solutions with different electrical resistivity (20,10000,20000) ω.cm repesenting the electrical resistivity of (soil, sand and porcelanite stone ,gravel) respectively. the solution resistances are very low as would be the case with a specimen having a high corrosion rate ,the effect of the solution resistance may be a significant portion of the corrosion current reading , where corrosion rate can by determined be the following relationship [8]: corrosion rate (mpy) = 0.13*i corr. e/d …(3) where : icorr: corrosion current density µa/cm2 e :equivalent weight (for steel= 25.5) d :density of metal(for steel = 7.9 gm/cm3) the polarization gave us values corrosion potential (ecorr) y-axis and corrosion current density (icorr) x-axis as shows in (table 6) and (fig. (6), (7), (8)). the result higher corrosion current density (icorr) at low electrical resistivity values (20ω.cm) this indicates the high corrosion rate , while lower corrosion current density (icorr) in high electrical resistivity solution (20000ω.cm) indicates the lower corrosion rate. results show a propotional relationship of corrosion rate with current density, but inversily proportional with resistivity, this is due to the reduction of water content, the density increases (soil,sand,porcelanite and gravel) which reflects at the values of resistivities.in (fig. 9) shows relationship between corrosion rate and corrosion current density . show presenceis a difference in the rate of corrosion between two methods corrosion rate higher in polarization method than weight loss the reason , the corrosion behavior of iron and steel buried in the soil approximates , in some respects, the behavior of the iron and steel on total immersion in water [4]. when soil resistivity value (> 20,000ω.cm) essentially noncorrosive [1], this point different corrosion between soil and water, very pure or very soft waters are often excellent solvents for metallic ions. if these waters are very pure or very soft waters are often excellent solvents for metallic ions [9]. rates corrosion in media depended on the characteristics of the media buried metal structure , many factors affected of corrosion rate, important factor affected electrical resistivity and porosity . lower corrosion rate in media with high electrical resistivity and less porosity (more dense ) .than gravel of these four media is best media protect from corrosion . amel s. merzah al-khwarizmi engineering journal, vol. 10, no. 2, p.p. 6574 (2014) 73 4. conclusions 1. corrosion rates of structure metal buried in media depend on the characteristics of this media (electrical resistivity , porosity, hydraulic permeability which describes how pores are interconnected, etc.). 2. electrical resistivity of media is important factor effect on corrosion rate for metal buried in it. 3. select best media for buried metal structure with low corrosion rate. sand , porcelainte stone and gravel have best corrosion resistance compared to soil. 4. gravel is the best media with higher corrosion resistance. 5. reference [1] roberge p.r, "handbook of corrosion engineering", mcgraw-hill,usa 2000. [2] robert baboian,"corrosion test and standards: application and interpretation", second edition, astm stock number: mn120-20nd, 2005. [3] córdoba v. c., mejía m. a., echeverría f., morales m. and calderón j. a. ,"corrosion mitigation of buried structures by soils modification", chilean journal of engineering, vol. 19,no.3,pp486-497, 2011. [4] winston r. r., herbert u. h., ‘’corrosion and corrosion control’’, fourth edition, usa, 2006. [5] m. romanoff, “underground corrosion,” nbs 579, ntis pb 168,350, national bureau of standards, april 1957. [6] 6.“standard method for field measurement of soil resistivity using the wenner four electrode method,” g 57, annual book of astm standards, american society for testing and materials, 1995. [7] naser korde," cathodic protection of steel pipelines using solar energy", msc thesis, department of production engineering and metallurgy, university of technology, 2012. [8] formerly efm, engineering filed handbook, engineering field manual notice nb-21, 1979. [9] asm handbook, “corrosion fundamentals, testing, and protection”, vol .13a, asm,2003. )2014( 6574، صفحة 2، العدد10دجلة الخوارزمي الھندسیة المجلم امل صالح مرزه 74 حمایھ التأكل للفوالذ الكاربوني المدفون بوساطة تغیر الوسط ***ساره كریم محمد** محمد ھلیل حافظ * امل صالح مرزه بغداد الكلیھ التقنیھ*** ،* ةالجامعھ التكنلوجی/ قسم تكنلوجیا النفط** amelmerza@yahoo.com :البرید االلكتروني* drmhh1962@gmail.com :البرید االلكتروني** sarah_materials@yahoo.com :البرید االلكتروني*** الخالصة حیث . الھدف من ھذا العمل ھو السیطرة على تأكل المعدن المدفون بطریقة استبدال أوساط،وھذه الطریقة تعتمدعلى خصائص كل وسط اوساط مختلفة واختیار افضل وسط حامي من التأكل واألوساط تشمل حسبت معدالت التأكل لعینات من فوالذ منخفض الكاربون في قیس فقدان الوزن ،حسبت معدالت التأكل بطریقتین طریقة فقدان الوزن وطریقة االستقطاب ) . صخر البورسلینات والحصى،الرمل،التربة( ً ٩٠(بدفن العینات في كل وسط من ھذه االوساط لمده ستقطاب تضمنت تحضیر محالیل ملحیة تملك مقاومیات كھربائیة وطریقة أال) یوما صخر >الرمل >التربة(اظھرت نتائج معدالت التأكل على نحو التالي.مكافئة لألوساط المستخدمھ وحساب معدالت التأكل في ھذه المحالیل ص ھذا الوسط من مقاومیة كھربائیة عالیة اقل معدالت تأكل حصلت للعینات المدفونة في الحصى بسب خصا).الحصى >البورسلینات .ومسامیة قلیلة واقل معدالت تأكل حدثت للعینات المدفونة في التربة mailto:amelmerza@yahoo.com mailto:drmhh1962@gmail.com mailto:sarah_materials@yahoo.com 72-80 al-khwarizmi engineering journal al-khwarizmi engineering journal,vol. 12, no. 4, p.p. 7280 (2016) prediction of surface roughness and material removal rate in electrochemical machining using taguchi method abbas fadhil ibrahim department of production and metallurgy engineering/ university of technology email:abbasfadhel-2006@yahoo.com (received 31 january 2016; accepted 5 june 2016) http://dx.doi.org/10.22153/kej.2016.06.001 abstract electrochemical machining is one of the widely used non-conventional machining processes to machine complex and difficult shapes for electrically conducting materials, such as super alloys, ti-alloys, alloy steel, tool steel and stainless steel. use of optimal ecm process conditions can significantly reduce the ecm operating, tooling, and maintenance cost and can produce components with higher accuracy. this paper studies the effect of process parameters on surface roughness (ra) and material removal rate (mrr), and the optimization of process conditions in ecm. experiments were conducted based on taguchi’s l9 orthogonal array (oa) with three process parameters viz. current, electrolyte concentration, and inter-electrode gap. signal-to-noise (s/n), the analysis of variance (anova) was employed to find the optimal levels and to analyze the effect of electrochemical machining parameters on ra and mrr. the surface roughness of the workpiece was decreased with the increase in current values and electrolyte concentration while causing an increase in material removal rate. the ability of the independent values to predict the dependent values (r2) were 87.5% and 96.3% for mean surface roughness and material removal rate, respectively. keyword: ecm, carbon, mrr, , ra, taguchi method. 1. introduction electrochemical machining (ecm) is among the well recognized non-conventional manufacturing processes in industry. an electrical current passes through an electrolyte solution between an anode (workpiece) and a cathode (tool). the workpiece is eroded in accordance with faraday’s law of electrolysis [1]. though, the principle of electrolysis was in use for a long time in a process called electroplating. but with certain modifications, ecm is often characterized as “reverse electroplating”, with difference of no deposition of workpiece on cathode. in today’s manufacturing era, machining process quality relies on surface finish of the machined workpiece to a great range. ecm contributed a lot to obtain good surface finish while machining. to enhance the machining performance, the precise selection of machining parameters is still a demanding job in ecm process as it is very difficult process involving so many unpredictable chemical reactions during machining. various investigations have been carried out for improving the surface roughness (ra) process characteristic of ecm process by numerous researchers [2]. neto, j., et al. [3] took material removal rate (mrr), surface roughness (ra) and over-cut as response parameters for studying process variables in electrochemical machining (ecm) of valve-steel. the surface roughness decreased with the increase in tool feed rate. ganesan, g., et al. [4] used non-dominated sorting genetic algorithm-ii (nsga-ii) to optimize the ecm process. production rate was increased considerably by decreasing machining time. chakradhar, d., and gopal, a., [5] found tool feed rate as more influencing machining abbas fadhil ibrahim al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 7280(2016) 73 parameter by performing anova in investigation and optimization of en-31 steel, using grey relation analysis. acharya, b.r., et al. [6] adopted response surface methodology (rsm) to investigate the effect of four machining parameters, i.e., electric current, voltage, electrolyte flow rate and inter-electrode gap on mrr and surface roughness (sr). the surface roughness was influenced greatly by current. goswami, r., et al. [7] reported the ecm of mild steel and aluminium by using taguchi method to analyze and predict the optimal process input parameters for material removal rate (mrr) and surface roughness (ra). for both materials, current was the most significant machining parameter for surface roughness. senthilkumar, et al. [8] developed a mathematical model in terms of machining process and studied the effect of various process parameters, such as electrolyte flow rate, electrolyte concentration, voltage and tool feed rate on the material removal rate and surface roughness sathiyamoorthy, v., and sekar, t., [9] used nacl aqueous solution in electrochemical machining of die steel and three electrolyte jet patterns namely straight jet in circular, inclined jet in circular and straight jet in spiral to analyze the influence of electrolyte distribution on the surface roughness and material removal rate. parameters for ra and mrr prediction in ecm of lm25 al/10%sicp composite. in the past, various researchers have attempted to study and optimize ecm process by taking process input parameters, such as electric current, voltage, tool feed rate, electrolyte concentration, electrolyte flow rate, inter-electrode gap, etc. and analyzing their effect on response parameters viz. material removal rate, surface roughness, radial overcut etc., which decide the cutting performance. a very rare work has been done by taking work material as an input parameter for experimental study of ecm, as performance of process also be influenced by type of work material due to its chemical and electrical characteristics. in spite of other important input parameters, the workpiece material is one of the important parameter, which affects the surface roughness. as ecm is an atomic dissolution of work material involving chemical reactions during machining, so the chemical characteristics of work material affect the response parameters [2]. taguchi method (tm) was proposed by genichi taguchi, a japanese quality management consultant. the aim of tm is to reduce the number of experiments to study the entire parameter space. the experimental results are then transformed into a signal-to-noise (s/n) ratio, a determination of quality characteristics deviating from or nearing to the desired values. there are three categories of quality characteristics in the analysis of the s/n ratio, i.e., the nominal is the better , the higher is the better , and the lower is the better. the equation used for calculating s/n ratio for obtaining the smallest ra is:       −= ∑ = n i iy n ns 1 2)( 1 log10/ … (1) the quality characteristic for material removal rate (mrr) is of the-higher-the-better type. the equation used for calculating s/n ratio for obtaining the largest mrr is::       −= ∑ = n i iyn ns 1 210 )1( 1 log10/ ;i=1,2,…n …(2) where n: number of replications. yi: observed response value in the current research work, an effort has been made to study the effect of input parameters on the surface roughness and material removal rate by selecting current with electrolyte concentration and inter-electrode gap as another two parameters and optimize these input parameters to improve ra and mrr, using brass electrode and carbon steel (1020) anode in taguchi method. 2. experimental work the experimental setup includes an electrochemical machining unit and electrolyte tank. nacl aqua solution was used as the electrolyte. the electrolyte is filled in the electrolyte tank and is supplied to the machining unit through an electrolyte pump. brass tool has been used as an electrode as shown in figure 1, and the electrolyte passes on the electrode. the ecm is shown in figure 2. abbas fadhil ibrahim al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 7280(2016) 74 φ 10 mm 70 mm fig. 1. tool used in experimental work. fig. 2. electrochemical machine. the machining unit includes a spindle through which the electrode is inserted. the workpiece is fixed in a small vise and moved to the appropriate position using hand wheels. the maximum permissible current was set, and the inter electrode gap was accurately set by touching the electrode and then feeding the electrode in reverse direction for a specified time [11]. a tool of dia.8 mm was set throughout the experiments. the material to be used as tool or electrode should posses desirable properties, like easily machinable, low wear rate, good conductor of electricity and heat, cheap and readily available. in this experiment, brass was taken as (tool) electrode material at cathode. it is designed in circular shape so as to cut the cavity in workpiece in the similar profile. then, the machining was done for the set values in table 3. carbon steel (1020) workpiece with a hardness of bhn 163 was used. the chemical compositions of tool and workpiece material are presented in table.1. and table.2., respectively, which were tested in central organization for standardization and quality control . the experiments were conducted by setting different levels of parameters, and the results were recorded. the roughness measurement device was used to measure the roughness after every test to compare the results, and a weighing electronic machine with ±1mg accuracy was used for measuring the material removal rate (mrr) in gram.the complete working environment of the experiments is shown intable.3. reaction tank tool holder tool feeding negative pole positive pole electrolyte pump power supply abbas fadhil ibrahim al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 7280(2016) 75 table 1, tool material composition (brass). elements zn pb sn p si s as ag bi cd sb cu weight% 35.5 1.7 0.157 0.006 0.002 0.009 0.008 0.004 0.006 0.004 0.03 remain table 2, workpiece material composition (carbon steel 1020). elements c% mn% p% s% fe% carbon steel (1020) 0.2 0.3 0.04 0.05 remain table 3, input factors of ecm. factor current (amp), a electrolyte concentration (g/l), b inter-electrode gap(mm), c 1 50 75 0.5 2 60 100 1 3 70 125 1.5 the experiments were conducted according to taguchi analysis by using the machining setup and the designed circular shaped electrodes. the control conditions, like applied voltage, feed rate, electrolyte concentration, and pressure, were varied to conduct nine different experiments and the weights of the workpieces were taken for calculation of material removal rate. mrr was calculated by the following formula as given: mrr = (initial weight-final weight) / time ...(3) during each drilling operation based on taguchi l9 orthogonal array, the machining time was noted down. the weights of the workpieces were measured by the digital weighing machine before and after each operation. the standard taguchi orthogonal array of l9 (34) has been employed. table (1) shows this array with cutting parameters used here in this research and combination of their levels for each experiment. table 4, ecm parameters according to taguchi method no. paramete rs coded parameters of ecm ra measured (µm) ra predicted (µm) mrr measured (gm/sec) mrr predicted (gm/sec) s/n for ra s/n for mrr a b c curren t (amp) electrolyte conc. (g/l) ieg (mm) 1 1 1 1 30 75 0.5 2.07 2.0956 0.0146 0.0139 -6.32 36.71 2 1 2 2 30 100 1 2.34 2.1556 0.0139 0.0143 -7.38 37.13 3 1 3 3 30 125 1.5 2.36 2.5189 0.0113 0.0117 -7.46 38.94 4 2 1 2 50 75 1 2.23 2.3889 0.0122 0.0126 -6.96 38.27 5 2 2 3 50 100 1.5 2.86 2.8856 0.0110 0.0103 -9.13 39.17 6 2 3 1 50 125 0.5 2.03 1.8456 0.0135 0.0139 -6.15 37.39 7 3 1 3 70 75 1.5 3.12 2.9356 0.0141 0.0145 -9.88 37.02 8 3 2 1 70 100 0.5 1.87 2.0289 0.0180 0.0184 -5.44 34.89 9 3 3 2 70 125 1 1.93 1.9556 0.0191 0.0184 -5.71 34.38 3. results and discussion as illustrated in figure 3, the comparison of the experimental data and the model reveals that the prediction is satisfactory for surface roughness. surface roughness for each experiment is measured using portable surface finish tester, the regarding between measured and predicted material removal rate as shown in figure 6, it is clear there is an agreement in more points between two bar charts , this shows the efficiency taguchi method to predict the variables. the ability of the independent values to predict the dependent values) r2 pieces is 87.5% and 96.3% for mean surface roughness and material removal abbas fadhil ibrahim al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 7280(2016) 76 rate respectively the average (mean) of these characteristics and s/n ratio (in decibels) is shown for each characteristic.. to investigate the designed conditions and to indicate the conditions is the main purpose of used the analysis of variance (anova), which significantly affect the quality characteristic. this analysis helps to find out the relative contribution of finishing parameter in controlling the response of the ecm process. in the analysis, the summation of the square deviation is calculated from the value of s/n ratio by separating the total variability of s/n ratio for each control parameter. the “p%” value in tables (5 and 6) shows the effectiveness of each condition toward affecting the related response characteristics within the limited range. from table (5), it is concluded that the current (parameter a) is the most significant parameter for minimum surface roughness, and the electrolyte concentration (parameter b) is the next significant parameter for minimum ra. figures (4 and 5) shows the plot of the means of the surface roughness and the means of s/n ratio . in the figures it is concluded that the optimal parametric combination for minimum surface roughness is a1 b3 c1, i.e., at 30 amp current, 125 g/l electrolyte concentration and 0.5 mm inter-electrode gap. the lowest surface roughness height ra was suggested that the parametric combination within the considered range as mentioned above gives. from table (6), it is concluded that the electrolyte concentration (parameter b) is the most significant parameter for maximum mrr, inter-electrode gap (parameter c) is the next significant parameter for maximum mrr. figures (7 and 8) shows shows the plot of the means of the material removal rate and the means of s/n ratio. the optimal parametric for maximum material removal rate is a3 b3 c1, i.e., at 70 amp current, 125 g/l electrolyte concentration and 0.5 mm interelectrode gap. the minimum quantity of the tool metal removed is considered as an indicator that the tool life will be longer at these levels combinations of cutting conditions. table 5, analysis of variance for means (ra). source df seq.ss adj.ss adj.ms f p a 2 0.02056 0.02056 0.01028 0.11 0.897 b 2 0.21056 0.21056 0.10528 1.17 0.461 c 2 1.03149 1.03149 0.51574 5.74 0.148 residual error 2 0.17976 0.17976 0.08988 / / total 8 1.44236 / / / / table 6, analysis of variance for means (mrr). source df seq.ss adj.ss adj.ms f p a 2 0.000039 0.000039 0.000019 17.08 0.055 b 2 0.000002 0.000002 0.000001 0.68 0.594 c 2 0.000019 0.000019 0.000010 8.42 0.106 residual error 2 0.000002 0.000002 0.000001 / / total 8 0.000062 / / / / (df=degree of freedom, ss=sum of square, ms=mean of square, p=percent of contribution) abbas fadhil ibrahim al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 7280(2016) 77 fig. 3. the diagram of the measured and predicted surface roughness for the experimental data. 705030 2.8 2.7 2.6 2.5 2.4 2.3 2.2 2.1 2.0 1.9 12510075 1.51.00.5 current (amp) s u rf a c e r o u g h n e ss ( u m ) electrolyte conc. (g/l) ieg (mm) main effects plot for means (ra) data means fig. 4. main effects plot for means (ra) 705030 -6.0 -6.5 -7.0 -7.5 -8.0 -8.5 -9.0 12510075 1.51.00.5 current (amp) m e a n o f s n r a ti o s electrolyte conc. (g/l) ieg (mm) main effects plot for sn ratios data means signal-to-noise: smaller is better fig. 5. the mean s/n ratio plot for (ra). 0 0.005 0.01 0.015 0.02 0.025 1 2 3 4 5 6 7 8 9 test number m te ri al r em o va l r at e (g ra m /s ec ) measured mrr predicted mrr fig. 6. the diagram of the measured and predicted material removal rate for the experimental data. 0 0.5 1 1.5 2 2.5 3 3.5 1 2 3 4 5 6 7 8 9 test number s ur fa ce r ou gh ne ss ( um ) measured ra predicted ra abbas fadhil ibrahim al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 7280(2016) 78 705030 0.017 0.016 0.015 0.014 0.013 0.012 12510075 1.51.00.5 current (amp) m a te ri al r em o v al r a te ( g m /s ec ) electrolyte conc. (g/l) ieg (mm) main effects plot for means (mrr) data means fig. 7. main effects plot for means (mrr). 705030 -35.0 -35.5 -36.0 -36.5 -37.0 -37.5 -38.0 -38.5 12510075 1.51.00.5 current (amp) m ea n o f s n r at io s electrolyte conc. (g/l) ieg (mm) main effects plot for sn ratios data means signal-to-noise: larger is better fig. 8. the mean s/n ratio plot for (mrr). 4. conclusions from the present work the major conclusions which can be deduced can be summarized as follows: 1the ability of the independent values to predict the dependent values r2 pieces are 87.5% and 96.3% for mean surface roughness and material removal rate, respectively. 2the current (parameter a) is the most significant parameter, and the electrolyte concentration (parameter b) is next significant parameter for minimum ra. 3for minimum surface roughness the optimal parametric combination is a1 b3 c1, i.e., at 30 amp current, 125 g/l electrolyte concentration and 0.5 mm inter-electrode gap. 4the electrolyte concentration (parameter b) is the most significant parameter, and the interelectrode gap (parameter c) is next significant parameter for maximum mrr. 5the optimal parametric for maximum material removal rate is a3 b3 c1, i.e., at 70 amp current, 125 g/l electrolyte concentration and 0.5 mm inter-electrode gap. 6the surface roughness of the workpiece is decreasing with increasing in current values, while the material removal rate is increasing. 7the surface roughness of the workpiece is increasing with increasing inter-electrode gap while causing a decrease in material removal rate. 8increasing the electrolyte concentration causes decreasing of surface roughness and increasing material removal rate. 5. references [1] milan kumar das, kaushik kumar, tapan kr. barman and prasanta sahoo ,“optimization of surface roughness and mrr in electrochemical machining of en31 tool steel using grey-taguchi approach”, procedia materials science 6,pp. 729 – 740, 2014. [2] ramandeep singh, nikhil gandotra and ayyappan solaiyappan, “study of different work materials effect on surface roughnes in electrochemical machining process”, international journal of research in engineering and technology; vol. 04 issue: 07, pp. 505-513,2015. [3] neto, j., silva, e., and silva, m., “intervening variables in electrochemical machining”; journal of materials processing technology, vol. 179, pp. 92–96, 2006. [4] ganesan, g., senthilkumar, c., and karthikeyan, r.., “parametric optimization of electrochemical machining of al/15% sicp composites using nsga-ii,” transaction of nonferrous metal society of china, vol. 21, pp. 2294−2300, 2011. [5] chakradhar, d., and gopal, a., “multiobjective optimization of electrochemical machining of en31 steel by grey relational analysis” ,international journal of modeling and optimization, vol. 1, no. 2, pp. 113 – 117, 2011 . [6] acharya, b., mohanty, c., and mahapatra, s., “multi-objective optimization of abbas fadhil ibrahim al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 7280(2016) 79 [7] electrochemical machining of hardened steel using nsga-ii”, procedia engineering, vol. 51, pp. 554-560, 2013. [8] goswami, r., chouhan, r., and chaturvedi, v., “the implementation of taguchi approach on ecm process parameters for mild steel and aluminium” ,international journal of research in engineering & applied sciences, vol. 3, pp. 53 – 62, 2013. [9] senthilkumar, c., ganesana, g., karthikeyan, r., “influence of input parameter on characteristics of electrochemical machining process”, international journal applie science and engineering 11, pp.13-24, 2013. [10] sathiyamoorthy, v., and sekar, t., “experimental studies on improving the performance of electrochemical machining of high carbon, high chromium die steel using jet patterns”, carbon –science and technology, vol. 6, pp. 321 – 329, 2014. [11] hocheng h., sun y.h., lin s.c., kao p.s. , “a material removal analysis of electrochemical machining using flat-end cathode”, journal of materials processing technology 140 ,pp. 264–268, 2003. [12] jadhav p.v., bilgi d.s., sumit sharan, and rachit shrivastava, “experimental investigation on mrr of pulse electrochemical machining (pecm) based on taguchi method”, ijirset vol. 3, issue 1, pp. 8800-8809, 2014. ا �اھ�� �� )2016( 72-80، %$#� 4، ا�!�د����12 ا���ارز�� ا������� ا��������س 80 ا�*��7 ���1��6 ا�45#�� و�!�ل ازا�� ا���دة � ا�*�01 ا�/��و-����,� +�*��ام ط�'&� ت�-�ج� ا �اھ���� ���س ا#7 6!* ا#'5-4#234* /01/ ھ-,+* ا()' ج وا#"! دن abbasfadhel_2006@yahoo.com : ;ا(#5'9و) ا#:89, ا��:%� ا#'2c"m 9:'!k q= :0p @2hi* ا#'2hi@ ا#5?9و2p"2 =; واo,ة 2c"m n6 ت ا#'2hi@ ا#2cekl,ي #'2hi@ ا(5g ل ا#"!e,ة #c"4اد ذات ا#'4>2@ ا5#?9< =; >!:* و1` ا#'p "c# @2hi-* وvcp q#_p* 2@ان ا+'^,ام ظ9وف ا#'2hi@ ا#"] cek zcm @"!k *2#. ا#y ، ا#4v(ذ ا#"e وم #xc,أ،+: =q ا#4v(ذ، +: =q ا#'2' )42م، ا#-s س *2# m *1اء ذات دb3ا)' ج ا zcm @"!k 2 )* و+4فx#ا . cs:#ھ_ا ا ;d 2* و6!,ل ازا#* ا#"!,نsf0#4)* اi^#ا zcm @2hi'#92 ظ9وف اghk *+درا /k *2c"!c# *2# ["#9وف اj#ظ9و. وا *glg k6 *834; ا#!"4دp k *d4vx6 zcm د "'m) > رات :'l)ت اb7(ار ا,e64ل وcs"#ا b2p9k2@ وھ; ا#'2 ر وhik ف *#4hi"#ا(داة وا n2> 47ةv#ا . *(4i^#ا zcm @2hi'#92 ظ9وف اghk @2csk6]@ و)78 د ا#"0'84 ت ا) n8 :'#2@ اcskء و m4n#ا z#رة ا g)ا+'^,6` )0:* ا . n6 ا#'2 ر وb2p9k ا#"4csل n2o ;d ا)o:08 p ز8 دة d; 6!,ل از#* ا#" دةek@ ا#^4i)* ا8b> *#4hi"c# *2sf0# دة p /21@ . ا2sf0#* وzcm 6!,ل ازا#* ا#" دة /2e# > q:-'#ا zcm *ce'0"#2/ اe#2* اc> 1 ;4% ٩٦.٣و % ٨٧.٥ا#"!'",ة ھi^c#;#ا#'4ا zcm 2* و6!,ل ازا#* ا#" دةsf0#ا *( (microsoft word \323\332\317 \344\314\355\310 3545) al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 15, no. 1, march, (2019) p.p. 3545 experimental study of forcedconvection from horizontal rectangular fins array into air duct saad najeeb shehab department of mechanical engineering / college of engineering/ mustansiriyah university/ baghdad email: saadnajeeb16@ uomustansiriyah.edu.iq (received 24 april 2018; accepted 23 july 2018) https://doi.org/10.22153/kej.2019.07.001 abstract in this work, an experimental study has been done to expect the heat characteristics and performance of the forced-convection from a heated horizontal rectangular fins array to air inside a rectangular cross-section duct. three several configurations of rectangular fins array have been employed. one configuration without notches and perforations (solid) and two configurations with combination of rectangular-notches and circular-perforations for two various area removal percentages from fins namely 18% notches-9% perforations and 9% notches-18% perforations are utilized. the rectangular fins dimensions and fins number are kept constant. the fins array is heated electrically from the base plate with five different magnitudes of power-inputs. five several air flow velocity into a duct are utilized. the influence of fin geometry, air flow velocity, reynolds number and the surface heat flux on the heat-performance of forced heat convection have been simulated and studied experimentally. the experimental data indicates that the combination of 18% rectangular-notched and 9% circular-perforated rectangular fins array gave best forced heat performance in terms of average heat transfer coefficient about (25% 45%) and (7% 20%) compared than solid and 9% notches with18% perforations fins array respectively. five empirical correlations to predict the average nusselt number for the 18% notches with 9% perforations rectangular fins array at wide range of surface heat flux are deduced. the present data are compared with previous works and a good closeness in behavior is noticed. keywords: fins array, circular-perforations, rectangular-notches, forced-convection, experimental study. 1. introduction the heat characteristics and performance enhancement is a very importance subject of thermal-engineering. in general, the heat transfer from heated surfaces are enhanced by increasing the coefficient of convection heat transfer between a heated surface and it’s ambient or by fins and fins array to increase the surface area of heat transfer or by both methods. the convection heat dissipation occurs in a several engineering and industrial applications. the importance applications are cooling of electronic and microelectronic components, high power chips, transformers, electrical motors, solar collectors, systems of energy storage. toh and ong [1] introduced an experimental investigation of forced heat convection from vertically fins array through a narrow duct with different air velocities. they suggested an empirical equation as a function of geometrical fin parameters and air velocities. barhatte et al. [2] experimentally and numerically investigated and analyzed the natural heat convection over a rectangular fins array with and without notches. they utilized different notches types namely, rectangular, triangular and trapezoidal and multi heat inputs with constant dimensions of fins. they utilized the commercially available of fluent software version (6.3) to simulate the heat transfer from fins array to air ambient. they noted that more heat rate is transferred from triangular-notches fins array and found a very good agreement between experimental and saad najeeb shehab al-khwarizmi engineering journal, vol. 15, no. 1, p.p. 3545 (2019) 36 numerical results. hossain et al. [3] experimentally investigated the natural and forced heat performance from an aluminum pinfin arrays. they utilized seven pin fins with constant diameter of 8.2 mm and constant length of 70 mm was distributed in-line and various air flow rate. they concluded the forced convection heat transfer coefficient 43% greater than that free convection and they found the pin-fins increases the pumping power. dhanawade et al. [4] experimentally studied the enhancement of forced convection heat transfer over a horizontal flat plate with three types of rectangular-fins array namely solid, square perforation and circular perforation. they used several sizes of perforations and different values of reynolds number. they noted the size of perforation and reynolds number has a larger effect on values of nusselt number for both perforations type. also, they observed the percentage of enhancement of the squareperforated fins array is more than that of fins array with circulated-perforated. sivasubramaniyam [5] achieved an experimental investigation for forced circular pin-fins array with multi fin spacing and two different distributions like in-line and staggered in both directions of stream-wise and span-wise and different rate of air flow. he observed the heat transfer rate is larger in staggered distribution of fins with that of fins in-line distribution. also, he showed the average convection heat transfer coefficient increases than air flow velocity and reynolds number increase. wankhede and meshram [6] introduced an experimental investigation for free and forced-heat convection over a rectangular fins-array with and without inverted-notches in a horizontal position. the effects of fin spacing, surface heat flux, percentage of notched area and air-flow velocity on the characteristics and performance of convection heat dissipation were studied. they studied the influence of the inverted-notches on single-chimney flow pattern. they illustrated that the coefficient of convection heat transfer increases as percentage of notched area increases about 25% to 75% for cases of inverted notches fins array than that cases of fins array without inverted notches in natural and forced-heat convection. baqir et al. [7] experimentally studied the enhancement heat transfer and reduction of friction factor from staggered perforated pins fins array into a rectangular duct for wide range of reynolds number. they are studied three types of pin fins, solid, horizontal-vertical perforations and horizontal-vertical-lateral perforations. they concluded the nusselt number of pin fins includes horizontal-vertical perforations are 11% larger than those of solid pins and with horizontal-vertical-lateral perforations pins are 21% greater than those of solid pin fins. mousa [8] presented an investigation of air flow characteristics and forced heat convection around different extended surfaces shapes like triangular, rectangular and wavy. he found the turbulence intensity of rectangular-extended greater than that of triangular and wavyextended for same dimensions. mane s.n. and mane s.s. [9] presented a review on enhancement of forced heat convection from a several configurations of the notches fins array like rectangular, circular, triangular, and trapezoidal. they concluded that more heat transfer is from triangular-notches fins array than that other configuration of notches fins array. also, they noted the size of notch is very effects on heat transfer enhancement. shehab [10] experimentally simulated convection heat transfer over rectangular and v-fins array. he illustrated that the v-fins array gave better heat performance about 20% larger than rectangular fins array. shehab [11] experimentally studied the natural heat convection over rectangular fins arrays on a horizontal heated aluminum baseplate to ambient air with and without rectangular-notches portions influence. he investigated multi parameters such as fins number, percentage of notch area from a fin and surface heat flux on the coefficient of convection heat transfer and nusselt number. he observed that the heat convection performance for notch-fins array as coefficient of heat convection is 28% to 40% larger with solid-fins array. mageswaran et al. [12] experimentally investigated the forced convection over perforated square pin fins array with staggered distribution inside a duct. they used five different numbers of perforations and three different diameters of perforations for pin fin. they concluded that the number and diameter of perforations effects on convection heat performance. also, they found the best heat performance at the optimum perforated diameter (4 mm) and perforated number (3). the aim of present work is to introduce an experimental study for the forced heat convection over a heated horizontal rectangular fins array to ambient into a rectangular crosssection air duct with nozzle-diffuser ends utilizing three different configurations of saad najeeb shehab al-khwarizmi engineering journal, vol. 15, no. 1, p.p. 3545 (2019) 37 rectangular-fins arrays, one configuration is solid and two configurations with combination of rectangular-notches and circular-perforations for different area removal percentages from fin. also, the enhancement of forced heat convection using combination of notched and perforated fins. the influence of air flow velocity and surface heat flux are taken into consideration and studied. 2. experimental test-rig the experimental test-rig is designed and fabricated to cover the tests of present work as shown schematically and photographically in figures (1a to 1c). it consists of air duct, rectangular fins array, air fan, digital voltage regulator and instruments of measurement namely, digital voltage-current reader, metal vane anemometer model (yk-80am) to measure the inlet velocity of air flow in a duct, twelve-channels data logger thermometer and k-type of thermocouples wires. the rectangular fins array is manufactured from bright rolled aluminum plate as one piece with base-plate by cnc machine with dimensions of (130 mm length × 130 mm width × 3 mm thickness of base plate). it is electrically heated from a lower surface of base-plate using electrical heater wire is coiled around a thin sheet of mica and then is putted between two layers of mica have same dimensions of baseplat with thickness of 0.4 mm to obtain an homogenous heating of fins array base-plate and ensured the complete insulated of electrical heater. the dimensions of rectangular fins are (130 mm length × 26 mm height × 3 mm thickness). the fins array is housed in a 130 mm length × 130 mm width × 4.5 mm depth rectangular-hole milled on the upper surface of thermo-stone’s slab (200 mm length × 200 mm width × 100 mm thickness) to obtain a best thermal insulation and minimize the heat conduction losses from sides and lower of base-plate of fins array. the whole assembly is placed in a halfway of rectangular cross-section air duct with nozzle-diffuser ends. the air duct is manufactured from wood with thickness of 15 mm and it’s of 1000 mm long with an internal width (w) of 230 mm and internal height (b) of 100 mm, and the total length of duct with nozzle and diffuser ends is 1750 mm. the front face of air duct is made of 6 mm thickness clear acrylic sheet. multi-velocities air fan is fitted at the diffuser end of duct to provide a forced heat convection condition. the surface temperatures of the fins array are measured using five type-k calibrated thermocouples are fixed at various suitable positions in the lower surface of base-plate (four in corners and one in the center of base-plate). another three same thermocouples are utilized to measure the temperatures difference at lower and sides of fins array base-plate to evaluate the heat conduction losses through a thermo-stone’s slab as shown in figure (2). plus two thermocouples to record the inlet and outlet air temperatures inside a duct. the conditions of steady state for all tests of present work are attained from 45 to 90 minutes depending on the electrical power input. the readings of thermocouples have been recorded when the temperatures difference between two readings is ± ≤ 0.5 oc within ten minutes approximately. then, the surface temperatures of base-plate of fins array, air temperature into air duct, the voltage, and the current intensity passed to electrical wire heater are registered. a. sketch of an experimental test-rig. saad najeeb shehab al-khwarizmi engineering journal, vol. 15, no. 1, p.p. 3545 (2019) 38 b. photograph of an experimental test-rig. c. photograph of an air duct. 1. air duct 2. rectangular fins array 3. air fan 4. digital voltage regulator 5. digital voltage-current reader 6. metal vane anemometer 7. twelve-channels data logger thermometer 8. thermo-stone’s slab 9. flat table. fig. 1. experimental test-rig. fig. 2. schematic diagram of fins array assembly with thermocouples positions. 3. calculation procedures the present work is carried out for three different configurations of rectangular fins arrays namely, solid, with combination of 18% rectangular-notch and 9% circular-perforations and with combination of 9% rectangular-notch and 18% circular-perforations as shown in figure (3). the rectangular fin dimensions are fin length (l)= 130 mm, fin height (h)= 26 mm and fin thickness (t)= 3 mm and fins number (n)= 6 are kept constant for all configurations of fins array. table (1) illustrate the dimensions of fins arrays utilized. five different of surface heat fluxes (q) values namely, 1479, 2958, 4437, 5917 and 7396 w/m2 are utilized. the electrical power input (qi) to the wire heater is evaluted as a product of voltage (v), current (i): �� = � � … (1) it is transformed to heat energy and it transferred from a rectangular fins array to ambient air inside the duct by forced heat convection (qcv) plus heat losses due to heat radiation (qr) and heat conduction (qcd) lower and besides fins array. hence, �� = ��� + ��+ ��� … (2) the loss of heat radiation between surfaces of polished rolled aluminum fins array with emissivity of ε = 0.05 and the air temperature inside a duct (t∞) is computed from stefanboltzmann law. the losses of heat conduction (qcd) from lower and sides of fins array baseplate across thermo-stone’s slab (200 mm length × 200 mm width × 100 mm thickness) with thermal conductivity of kt= 0.15 w/m.k are calculated using fourier’s law [13, 14]. then, the forced-convection heat transfer (qcv) can be evaluted as follows: ��� = � � − (�� + ���) … (3) also, it is can be evaluted from newton’s equation of cooling as [13, 14]: ��� = ℎ�� ��(���� − ��) … (4) saad najeeb shehab al-khwarizmi engineering journal, vol. 15, no. 1, p.p. 3545 (2019) 39 the average forced-convection heat transfer coefficient (hav) can be evaluted as: ℎ�� = � � − (�� + ���) ��(���� − ��) … (5) �� = (�� + ��)/2 … (6) ���� = ∑ ����� !" … (7) where, ti and to are the inlet and outlet air temperatures respectively, ts is the local surface temperature. as is the surface area of rectangular fins array, and it computed as follows: solid rectangular fins array, �� = ($% − &'$) + 2&($ … (8) combination of rectangular-notches and circular-perforations rectangular fins array, �� = ($% − &'$) + 2&*($ − +�, + -��./ … (9) where, l is the fin length (base-plate side), n is the fins number, t is the fin thickness, h is the fin height, n is the perforations number in one fin, an is the notch area and ap is the perforation area, �, = $, (, … (10) �� = 24 3% … (11) the average nusselt number (nuav) based on the hydraulic diameter of the air duct (dh) as characteristics length can be calculated as [4, 15]: &4�� = ℎ�� 567� … (12) the reynolds number (re) for the flow into a duct can with the hydraulic diameter (dh) be expressed as [15]: 89 = 4 56: … (13) and the hydraulic diameter of rectangular crosssection air duct is [15]: 56 = 2 ; <(; + <) … (14) where, u is the velocity of air flow in a duct, w is the internal width of duct and b is the internal height of duct. the air properties used in experimental calculations are taken at film temperature (tf). it’s an approximation to temperature of the fluid into a convection boundary layer and evaluted as the arithmetic mean of average surface temperature (tsav) and ambient air temperature inside a duct (t∞) in (k) [15]. the percent error (%e) is the ratio of absolute error to the actual value, and computed as: %9 = >�?@� − ����>�?@� a 100 … (15) the mean relative squared-errors (mrse) is evaluted as: b8cd = e 1f − 1 g h�?@� − �����?@� i%j � ! k ! %⁄ … (16) where, (vexp) and (vcor) are experimental and correlated values respectively, j is the data number. a. solid b. 18% rectangular-notches with 9% circular-perforations c. 9% rectangular-notches with 18% circular-perforations. fig. 3. configurations of rectangular fins array. saad najeeb shehab al-khwarizmi engineering journal, vol. 15, no. 1, p.p. 3545 (2019) 40 table 1, dimensions of fins array studied. fins array configuration rectangular fin dimensions (l× h× t) mm fins numbe r rectangularnotch dimensions (ln× hn) mm circularperforations dimensions(dmm×n) surface area (as) m2 solid 130× 26× 3 6 ----0.0٥512 18% rectangular notches-9% circular perforations 130× 26× 3 6 84× 7 11.2× 3 0.0445 9% rectangular notches18% circular perforations 130× 26× 3 6 84× 3.5 11.2× 6 0.0445 4. results and discussion the present work simulates experimentally effect of the fins configurations (solid, with combination of rectangular-notches and circular-perforations), the percentage of area removal from fin, surface heat flux and the air flow velocity on forced-convection heat performance of a heated horizontal fins array inside air duct. figures (4a to 4c) illustrate behavior of the average forced heat convection coefficient versus surface heat flux for different configurations of rectangular fins array and different air velocities (u) ranging from 1.2 m/s to 3.6 m/s. they are clear that the average heat transfer coefficient (hav) gradually increases as surface heat flux (q) increases. also, the average heat-transfer coefficient (hav) increases with increasing air flow velocity in the duct. additionally, values of the average forced heat convection coefficient for 18% notches with 9% perforations rectangular fins array are larger about 25% to 45% than that solid fins array and larger about 7% to 20% than that 9% notches with 18% perforations rectangular fins array because of the combination of notches and perforations allow more fresh air comes inwards between fins channels and due to large increases in convection heat transfer coefficient. the notch of fin is removed from a non-effective part near of the stagnation zone of fin, while the perforations help to increase the turbulence of air flow into a duct and this, cause increases in forced-convection heat transfer rate from fins array surfaces. a. air flow velocity, u= 1.2 m/s b. air flow velocity, u= 2.4 m/s c. air flow velocity, u= 3.6 m/s fig. 4. average forced-convection heat transfer coefficient versus surface heat flux for three configurations of rectangular fins array at five different air flow velocities, (u= 1.2, 2.4 and 3.6 m/s). saad najeeb shehab al-khwarizmi engineering journal, vol. 15, no. 1, p.p. 3545 (2019) 41 fig. 5. average nusselt number versus reynolds number for surface heat flux, q= 1479 w/m2. fig. 6. average nusselt number versus reynolds number for surface heat flux, q= 7396 w/m2. figures (5) and (6) show the behavior of average nusselt number (nuav) against reynolds number (re) for solid, 18% notches with 9% perforations and 9% notches with 18% perforations rectangular fins arrays at surface heat flux, q= 1479 and 7396 w/m2. it is observed that the average nusselt number increases greatly with increasing reynolds number for all cases studied because the surface temperatures decrease with increasing air flow velocity into a duct. also it’s clear that the average nusselt number values for 18% notches with 9% perforations rectangular fins array are larger than those of solid and 9% notches with 18% perforations fins arrays. hence, the best fins array is 18% notches with 9% perforations because the combination of notches and perforations which increases the forcedconvection heat dissipation rate and turbulence of flow into an air duct and allow more cold air enters between fins channels and contacted the fins array hot surfaces. also, increasing the removed area of non-effective part from 9% to 18% of fins area improves the forcedconvection heat performance. furthermore, it’s observed that the average nusselt number improves about 15% to 42% when the surface heat flux increases because the average heat convection coefficient increases with percent reach about 45% larger than those solid fins array. figure (7) appears five correlations between average nusselt number and reynolds number for 18% notches with 9% perforations rectangular fins array for a multi-levels of surface heat flux (q) from 1479 w/m2 to 7396 w/m2. it is clear that the average nusselt number increases with increasing reynolds number. the following five empirical correlations are concluded: &4�� = 5.3475(89)n.o!op … (17) &4�� = 4.2607 (89)n.opqr … (18) &4�� = 1.9742(89)n.pops … (19) &4�� = 1.1661(89)n.t!! … (20) &4�� = 0.7885(89)n.tpru … (21) figures (8a and 8b) show a comparisons of the correlated average nusselt numbers (nuav-cor) with those experimental (nuav-exp) for 18% notches with 9% perforations rectangular fins array at surface heat fluxes, q= 1479 w/m2 and 7396 w/m2 using eqs. (17) and (21) respectively. they are appear that the percentage error (e%) of the experimental values situated between +10% and -10% of correlated values for surface heat fluxes, q= 1479 w/m2 and between +12% and -10% of correlated values for surface heat fluxes, q= 7396 w/m2, and the mean relative squarederrors (mrse) are 0.145 and 0.187 respectively. furthermore, the test is carried out on a smooth air duct using the same base-plate without fins array. then, the following empirical correlation is concluded: &4�� = 0.1522 (89)n.trrp … (22) and compared with dittus and boelter [1٥], and dhanawade et al. [4] correlations: &4�� = 0.024 (89)n.u (vw)n.o … (23) &4�� = 0.015 (89)n.u!t … (24) this is valid for turbulent flow in a rectangular smooth air duct as shown figure (9). it can be seen a good similarity in the behavior, but the present results gave values of average nusselt number higher those done in dittus and boelter and dhanawade et al. correlations because the different in duct dimensions, air flow velocity and surface heat flux levels. saad najeeb shehab al-khwarizmi engineering journal, vol. 15, no. 1, p.p. 3545 (2019) 42 fig. 7. analysis of present data for 18% notches-9% perforations rectangular fins array with concluded empirical correlations. a. surface heat flux, q= 1479 w/m2 b. surface heat flux, q= 7396 w/m2 fig. 8. comparison of the correlated average nusselt numbers (nuav-cor) with those of experimental (nuav-exp) for 18% notches-9% perforations rectangular fins array. fig. 9. comparison of the present work for a smooth duct with dittus and boelter [1٥] and dhanawade et al. [4] correlations. saad najeeb shehab al-khwarizmi engineering journal, vol. 15, no. 1, p.p. 3545 (2019) 43 5. conclusions the present work has achieved an experimental study of an electrically heated horizontal rectangular fins array inside an air duct subjected to forced-convection. three configurations of rectangular fins namely, solid, combination of 18% rectangular-notches with 9% circular-perforations and combination of 9% rectangular-notches with 18% circularperforations are utilized with constant fins number and dimensions. the important conclusions can be drawn: 1. the rectangular fins array includes combination of 18% notches with 9% perforations gave best forced heat performance in terms of average heat convection coefficient about (25% to 45%) and (7% to 20%) larger than those solid and 9% notches with 18% perforations fins array respectively. 2. increasing of the removed area of noneffective part (notches) from 9% to 18% of fins area improves the heat characteristics and gave maximum values of average heat transfer coefficient (hav -max= 126 w/m2. k) and nusselt number (nuav -max=592). 3. the average nusselt numbers increases strongly from 34% to 48% approximately with increases reynolds numbers for all studied rectangular fins arrays. 4. the average nusselt number improves clearly about %15 to 42% with increasing surface heat flux for all studied cases. 5. five empirical correlations to predict the average nusselt number for the 18% notches with 9% perforations rectangular fins array at wide range of surface heat flux are concluded. nomenclature an notch area, (m2) ap perforation area, (m2) as surface area of heat transfer, (m2) b internal height of air duct, (m) d diameter of perforation, (m) dh hydraulic diameter of air duct, (m) h forced-convection heat transfer coefficient, (w/m2.k) h fin height, (m) hn notch height, (m) i input current, (a) ka thermal conductivity of air, (w/m.k) l fin height (base-plate side), (m) ln notch length, (m) n number of fins n perforations number nu nusselt number q surface heat flux, (w/m2) qcd loss of heat conduction, (w) qcv rate of forced-convection heat transfer, (w) qi electrical power input, (w) qr loss of heat radiation, (w) re reynolds number t fin thickness, (m) t∞ air temperature into a duct, (oc) tf film temperature, (k) ti inlet air temperature, (oc) to outlet air temperature, (oc) ts surface temperature, (oc) u velocity of air flow, (m/s) v voltage, (v) w internal width of air duct, (m) greek letters ν kinematic viscosity, (m2/s) subscript symbols av average 6. references [1] toh, k.c. and ong, y.k. “forced convection heat transfer from vertically stacked fin arrays with a shrouding wall “, international communications in heat and mass transfer journal, vol. 19, issue 3, pp.373-384, 1992. [2] barhatte, s.h., chopade, m.r. and kapatkar, v. n., “experimental and computational analysis and optimization for heat transfer through fins with different types of notch “, journal of engineering research and studies, v. 2, issue 1, pp. 133-138, 2011. [3] hossain, m. s., ahamed, j. u., akter, f., das, d. and soha, s. “heat transfer analysis of pin fin array “, proceedings of the international conference on mechanical engineering and renewable energy, bangladesh, 24-27 december 2013. [4] dhanawade, k. h., sunnapwar, v. k. and dhanawade, h. s. “thermal analysis of square and circular perforated fin arrays saad najeeb shehab al-khwarizmi engineering journal, vol. 15, no. 1, p.p. 3545 (2019) 44 by forced convection”, international journal of current engineering and technology, special issue-2, pp. 109-114, february 2014. [5] sivasubramaniyam, r. "performance analysis on array of circular fins through forced convection", international journal of engineering research and technology, vol. 7, no. 1, pp. 1-8, 2014. [6] wankhede, s.d. and meshram, c.b. "experimental study and investigation of heat transfer from horizontal rectangular inverted notch fin arrays (infas) under natural and forced convections ", international journal researchers, scientists and developers, vol. 2, no. 1, pp. 13-16, 2014. [7] baqir, a.s., qasim, a. and adnan, a. "experimental study for staggered perforated array of pins like fins in a rectangular air cross flow", the iraqi journal for mechanical and material engineering, vol. 14, no. 2, pp. 261-275, 2014. [8] mousa, n. a. "study on flow characteristics and heat transfer behavior around different geometrical corrugated extended surfaces", alkhwarizmi engineering journal, vol. 11, no. 2, pp. 31-44, 2015. [9] mane, s.n. and mane, s.s. "a review on heat transfer from different types of notch fin arrays under forced convection to increase heat energy transfer", international journal on recent technologies in mechanical and automobile engineering, vol. 2, issue 6, pp. 15-18, 2015. [10] shehab, s.n. shehab, s.n. "experimental simulation of natural heat convection from finned vertical plate with different inclinations', al-khwarizmi engineering journal, vol. 12, no. 3, pp. 61-71, 2016. [11] shehab, s.n. "experimental study of free-convection from rectangular fins array on a heated horizontal plate with notch effects", al-nahrain journal for engineering sciences, vol. 20, no. 1, pp. 140-148, 2017. [12] mageswaran, c., karthikeyan, r. and muthukumaran, r. "heat transfer enhancement of perforated square pin-fin array in a rectangulr duc", international journal for research in applied science and engineering technology, vol. 5, issue ix, pp. 1826-1832, 2017. [13] cengel, y. a. "heat transfer: a practical approach", mcgraw-hill companies, second edition, usa, 2008. [14] rajput, r.k. "heat and mass transfer", s. chand and company ltd., fifth revised edition, india, 2012. [15] bejan, a. "convection heat transfer", john wiley and sons, inc., fourth edition, usa, 2013. )2019( 3545، صفحة 1د، العد15دالهندسية المجلجلة الخوارزمي م سعد نجيب شهاب 45 دراسة تجريبية للحمل القسري من مصفوفة زعانف مستطيلة أفقية داخل مجرى هواء سعد نجيب شهاب ة / بغدادمستنصريقسم الهندسة الميكانيكية / كلية الهندسة / الجامعة ال uomustansiriyah.edu.iq16saadnajeeb @البريد اللكتروني: الخالصـة ة مس$خنة ال$ى للتنب$ؤ ب$األداء والخص$ائص الحراري$ة للحم$ل الح$راري القس$ري م$ن مص$فوفة زع$انف مس$تطيلة أفقي$يتناول هذا البحث دراسة تجريبي$ة بة (ب$دون أش$كال مختلف$ة م$ن مص$فوفات الزع$انف المس$تطيلة، الش$كل األول يتض$من زع$انف ص$ل ةالهواء داخل مجرى مستطيل المقطع. أس$تخدمت ثالث$ %١٨نف$ة ه$ي، شقوق مستطيلة الشكل وثقوب دائري$ة الش$كل بنس$بتين مختلفت$ين للمس$احات المزال$ة م$ن الزع ن يتضمناناخرن اآلشقوق وثقوب) والشكال م تثبي$ت أبع$اد الزع$انف وع$ددها لجمي$ع الح$االت. ت$م تس$خين مص$فوفة الزع$انف كهربائي$ا م$ن القاع$دة ت$ثقوب. %١٨ -% شقوق٩ثقوب و %٩ -شقوق س$رعة جري$ان و ودراس$تها دمت خمس سرع لجريان اله$واء داخ$ل المج$رى . ت$م محاك$اة ت$أثير ش$كل الزع$انفبخمس قيم مختلفة من القدرة الداخلة. أستخ يلة زع$انف المس$تطالهواء وعدد رينولد والفيض الحراري للسطح عل$ى األداء الح$راري للحم$ل القس$ري عملي$ا. أظه$رت البيان$ات العملي$ة أن مص$فوفة ال ً تعطي أداء حراري$ %٩ثقوب دائرية بنسبة و %١٨التي تتضمن شقوق مستطيلة بنسبة ً قس$ري ا ارة بالحم$ل أكب$ر أفض$ل بدالل$ة مع$دل معام$ل أنتق$ال الح$ر ا ثق$$وب. أس$$تنتجت خم$$س عالق$$ات %١٨ش$$قوق م$$ع %٩بمص$$فوفتي الزع$$انف الص$$لبة والمتض$$منة ) مقارن$$ة%٢٠ -%٧) و (%٤٥ -%٢٥بح$$والي ( ورن$ت ق ،ثق$وب لم$دى واس$ع م$ن الف$يض الح$راري للس$طح %٩ش$قوق م$ع %١٨ع$انف المتض$منة أرتباطية عملية للتنبؤ بمعدل رقم نس$لت لمص$فوفة الز ً البيانات المقدّمة مع دراسات سابقة وأظهرت تقارب في السلوك. اً جيد ا رافع واسيل وبان al-khw arizmi engineering journal,vol. experimental study on the effect of insertion of copper lessing rings in phase change material (pcm) on the performance of thermal energy storage unit rafa a.h albaldawi* *,**,*** department of mechanical engineering (received abstract one of the most suitable materials to be change materials, but a problem of slow melting and solidification processes made many researchers focusing on how to improve their thermal properties. this phase change material. the enhancing method was (paraffin wax). the effect of diameter for the used rings was studied by using two different diameters ( also, three volumetric percentages of rings addition (3%, 6% and 10%) were process was done with four velocities for each case. the obtained results indicated that the maximum volumetric percentage gave a diminished time for melting and maximized the heat transfer in both pcm and air sides as compare with the case of no rings, but the effect of these rings had lower effect on the solidification time. in case of 1 cm rings diameter minimum time for melting was obtained for both 3% and 6% volumetric percentages as compared with the same percentages in case of 0.5 cm diameter rings, while diameter rings for the same previous percentage. also i utmost outlet temperature and with the maximum one keyword: thermal energy storage systems, latent heat storage, phase change materials, heat transfer enhancement. 1. introduction the increase of fuel cost and impurities in environment due to conventional consumption, increase the importance renewable energy and make alot of research seeking for its new sources, and the solar energy plays the big role of renewable energy. the mechanism of storing thermal energy is now having a lot of interest. the storage of thermal energy is done by the using of thermal energy storage systems (tess). thermal energy storage stored as sensible heat, latent heat and thermoc combination of these [1]. at those days, most of arizmi engineering journal,vol. 11, no. 4, p.p. 6072 (2015) experimental study on the effect of insertion of copper lessing phase change material (pcm) on the performance of thermal energy storage unit a a.h albaldawi* aseel k. shyaa** ban m.h. hammendy*** mechanical engineering/ college of engineering/ al-mustansiriya university *email: rafa_a70@yahoo.com **email: aseelkhshyaa@yahoo.com *** email: b.hammendy@yahoo.com (received 3 march 2015 ; accepted 16 june 2015) one of the most suitable materials to be used in latent heat thermal energy storage system (lhtes) are phase change materials, but a problem of slow melting and solidification processes made many researchers focusing on how his experimental work concerned with the enhancing of thermal conductivity of phase change material. the enhancing method was by the addition of copper lessing rings in phase change material (paraffin wax). the effect of diameter for the used rings was studied by using two different diameters ( rings addition (3%, 6% and 10%) were tested for each diameter. process was done with four velocities for each case. the obtained results indicated that the maximum volumetric gave a diminished time for melting and maximized the heat transfer in both pcm and air sides as compare with the case of no rings, but the effect of these rings had lower effect on the solidification time. in case of 1 cm rings elting was obtained for both 3% and 6% volumetric percentages as compared with the same percentages in case of 0.5 cm diameter rings, while the latter with 10% volumetric percentage diameter rings for the same previous percentage. also it can be seen that the minimum velocity utmost outlet temperature and with the maximum one (v=3m/s), the minimum solidification time achieved. energy storage systems, latent heat storage, phase change materials, heat transfer enhancement. the increase of fuel cost and impurities in conventional fuel , increase the importance of lot of researchers the solar energy newable energy. the mechanism of storing thermal energy is now storage of thermal energy is done by the using of thermal energy thermal energy storage stored as sensible heat, latent heat and thermochemical or at those days, most of studies are conducted on materials t use of sensible and latent heat storage system which are as phase change materials. they are one of the most important applications of tess. studies conducted to compare phase change and sensible heat storages shown that a significant reduction in storage volume can be achieved using pcm compared to sensible heat storage there are three main types of pcm which organic-pcm, inorganic-pcm and eutectic in which each type is classified in to other subgroups. the pcm can be applied conveniently in many fields such as peak shift of electrical demands, solar energy utilization, waste heat recovery, al-khwarizmi engineering journal (2015) experimental study on the effect of insertion of copper lessing phase change material (pcm) on the performance of aseel k. shyaa** mustansiriya university in latent heat thermal energy storage system (lhtes) are phase change materials, but a problem of slow melting and solidification processes made many researchers focusing on how e enhancing of thermal conductivity of the addition of copper lessing rings in phase change material (paraffin wax). the effect of diameter for the used rings was studied by using two different diameters (0.5 cm and 1cm). tested for each diameter. the discharging process was done with four velocities for each case. the obtained results indicated that the maximum volumetric gave a diminished time for melting and maximized the heat transfer in both pcm and air sides as compare with the case of no rings, but the effect of these rings had lower effect on the solidification time. in case of 1 cm rings elting was obtained for both 3% and 6% volumetric percentages as compared with the percentage overcomes the 1 cm t can be seen that the minimum velocity (v=1m/s) gave the , the minimum solidification time achieved. energy storage systems, latent heat storage, phase change materials, heat transfer enhancement. on materials that making use of sensible and latent heat storage system as phase change materials. they are one of the most important applications of tess. studies conducted to compare phase change and sensible heat storages shown that a significant in storage volume can be achieved mpared to sensible heat storage [2]. there are three main types of pcm which are pcm and eutectic-pcm type is classified in to other can be applied conveniently in many fields such as peak shift of electrical demands, solar energy utilization, waste heat recovery, rafa a.h albaldawi al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 6072(2015) 61 intelligent air-conditioned buildings, temperature controlled greenhouses, electrical appliances with thermostatic regulators, energy storage kitchen utensils, insulation clothing and season storage these applications was viewed by molefi [3]. abhat [4] showed that the pcm to be used in the design of thermal-storage systems must have a thermodynamic, kinetics, chemical and economic criteria. the material to be used as pcm must have high latent heat, high thermal conductivity, low cost, uniformly melt, non toxic, not corrosive and melt within a practical required range of operation. due to the presence of most of these properties in paraffin wax that is making it occupies a considerable attention. however, paraffin waxes have inherently low thermal conductivity and so it takes considerable time to melt and solidify, which reduces the overall power of the thermal storage device and thereby restrict their application [5]. lamberg and sir'en [6] discuss melting process in pcm, during the phase change, the solid–liquid interface moves away from the heat transfer surface. thus, the surface heat flux decreases due to increasing thermal resistance of the growing layer of molten or solidified pcm. due to this problem, different authors studied methods for improvement of thermal conductivity such as the addition of metallic particles [7], porous media [8], pins [9], powder [11], fins [10], nanofibres [12] and graphite matrix [13]. velraj et al. [7] investigated three methods for improving of heat transfer rate of paraffin wax encapsulated in a cylindrical aluminum tube by the using of internal longitudinal aluminum fins, steel lessing rings and water bubbles. the results showed that the most effective enhancement method was by using of lessing rings (20% by volume) that decreased the freezing time by a factor of 9, and increase thermal conductivity to 10 times more than pure paraffin. also the finned tube with a volume fraction of 7% makes a reduction in the solidification time to about 4 times of that of no fins. zhao et al. [8] tested the melting and solidification processes of paraffin rt58 with metal foam (95% porosity, 10 pores per inch) embedded through it. the obtained results showed that the metal foam gave a significant effect on pcm especially during melting process and the small pore density and porosity gave the best results. the heat transfer rate increased up to 3-10 times and the solidification time reduced to half as compared with the case of pure pcm. also, a numerical model with two dimensions had been carried out to represent heat transfer in pcm with metal foam. suresh et al. [9] made an experimental method for the improvement of paraffin wax using different forms internal aluminum fins sinks (straight plate fins, rectangular pin fins and circular pin fins). the obtained results made an indication about the increased thermal performance by using of fins sinks. it can be seen that as the power input and fins numbers increased, the melting locations of pcm also increased and the best type was the circular one. castell et al. [10] studied the effect of using longitudinal vertical fins inside a cylindrical water tank which contain cylindrical pcm modules. the experiments were done with different fins height. it was found that the heat transfer coefficient was increased up to 3 times as compared with the case of no fins. also, these fins reduced the time required for solidification of pcm. mettawee and assassab [11] examined 80 µm aluminum powder mixed with pcm in a solar collector. it was found that the addition of 0.5 mass fraction of powder minimized the charging time up to 60% as compare with the case of pure paraffin. sanusi et al. [12] studies experimentally the effect of using graphite nanofibers on the solidification time with different aspect ratios. the obtained data showed that the addition of these fibers decreased the maximum temperature in the thermal containment unit up to 48%. also a reduction in the solidification time was occurred with these nanofibers up to 61% for the case of 1 aspect ratio. fedden [13] explored the effect of the addition of three different types of graphitized carbon foam to pcm. it was found that a rapid transfer of heat through pcm had been occurred by the help of this addition. also, a decreased in temperature rate of change obtained during melting and solidification processes and the less dense foam made a lower thermal conductivity. in this work, thermal conductivity of paraffin wax is improved by the addition of copper lessing rings with different volumetric percentages and two different rings diameter for the purpose of enhancing melting and solidification processes. rafa a.h albaldawi al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 6072(2015) 62 fig. 1. schematic sketch of the experimental model. 2. experimental work 2.1 experimental setup a small model of thermal energy storage system is employed. the experimental model consists of three main parts, entrance, test and exit region. the length of these sections is about 1070 mm, 300 mm, and 390 mm respectively, as shown in figure (1). a transition galvanized section (380 mm length) is used to connect the fan duct with the entrance region. a perspex sheet (9 mm thick) is used to manufacture each region. the test section has a dimension of 300 mm × 90 mm × 86 mm (l × w × h). this region is divided horizontally into two sides which are pcm and air sides. the height of each side is 32 mm and 42 mm, respectively. paraffin wax grade b (tmelt = 63.7°c) is used as a heat storage material. a copper plate (2.5 mm thick) is used to separate between pcm and air side in which it is fixed inside two opposite slots by the help of high temperature resistance silicon. another copper plate with the same thickness is placed in another opposite slots in the upper portion of pcm side. the last plate is used to separate between pcm and the heat source which is an electrical heater (150 w) and has dimensions of 280 mm × 65 mm. a process controller (model: esm-9950, emko company, working with maximum input module of 5 ampere and ± 0.25% accuracy) is connected in to the electrical heater to keep it at constant temperature (t = 100 °c) using an input thermocouple (tc13) connected into the controller. its probe fixed on the middle of the upper copper plate. five thermocouples are distributed uniformly along the axial center line of pcm side in which one of them is in the center and the other four thermocouples are beside the mid one with constant distance between each other. also one thermocouple is fixed in the midpoint of the lower copper plate. for air side, four thermocouples are also fixed along the axial center line of this side with constant distance between each. while the entrance and exit of the test region are also have a thermocouple in each. all thermocouples are type k with probe diameter of 0.5 mm and 2.2� � error. they connected into a temperature recorder (model: btm-4208sd, lutron electronic enterprise company, 0.1 ℃ resolution, ± (0.4 % + 0.5 ℃) accuracy and 1 to 3600 sec sampling time range) to record temperature data from thermocouples with time interval of 1 min. the whole test region is insulated by fiberglass insulation with aluminum outer surface and 12.5 mm thick. different velocities produced by a fan (0.27 a, 61 w, 60 hz and 3100 rpm.) in which it is controlled by a fan speed regulator by changing the entered voltage into the fan to get the required velocities. a hot wire anemometer (model: yk-2005ah, lutron electronic enterprise company, working range from 0.2 to 20.0 m/s, accuracy of ± (1% + o.1 m/s ) and 0.1 m/s resolution) is fixed in the entrance of the test region to sense the entrance velocity. rafa a.h albaldawi al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 6072(2015) 63 a b 2.2 experimental procedure the experimental tests are done with several cases. before the beginning of the test, the molten paraffin wax is poured into the pcm side of the test rig. care should be taken to leave an air gap approximately 10% from the whole pcm side volume to be safe with volume change of wax. the change in volume is occurred due to differences in densities between the liquid and solid wax. after the cooling of the whole wax, the melting test will be started by turning on the electrical heater until the lower copper plate reach a temperature of 63.7°c (melting wax temperature). then after that solidification process will begin immediately after the end of the melting process by turning the heater off and then turn the fan on. so that, solidification test will be end after the solidification of the whole wax and reaching approximately 30°c. so that, after the charging process ended, the discharging process started. the first test is done with pure paraffin and then with the addition of lessing rings of 0.5 cm diameter and then with lessing rings of 1 cm diameter. for each ring type, different volume percents should be studied (3%, 6% and 10%) and also four different velocities (1, 2, 2.5 and 3) m/s will be tested for each case. in all previous cases, data logger will record the whole thermocouples data for each minute. table (1) shows thermal and physical properties of used wax and air. table 1 physical and thermal properties of paraffin wax and air. material paraffin air property density (kg/m3) ρs=970 1.225 ρl=833 specific heat (j/kg.°c) 2871 1006.43 thermal conductivity (w/m.°c) 0.24 0.0242 viscosity (kg/m.sec) 0.0127 1.78 × 10-5 latent heat (j/kg) 273760 solid temperature (°c) 62 liquid temperature (°c) 68 2.3 lessing rings manufacturing a copper rings with tap at the center of them had been manufactured manually. two types of it are used in which one of them with 0.5 cm and another with 1cm diameter. each type was made from 0.15 mm copper sheet thick. the copper material selected rather than other materials types due to its high thermal conductivity. the purpose of this central tap is to increase the volume of each ring and make more contact surface area with pcm. these rings were made by the help of a cylindrical mold to get its required shape. figure (2) shows rings inside rig and figure (3) shows these rings. fig. 2. a. lessing rings d=0.5 cm inside test rig, b. lessing rings d=1cm inside test rig. rafa a.h albaldawi (a) fig. 3. a. rings manufacturing procedure 2.4. thermal conductivity measurements due to the importance of this property in this field of study, thermal conductivity had been measured by making use of hot disk thermal constants analyzer (model tps 500) in figure (4). this device is make measurement rapidly and accurately for different materials types. it make use of a mica disk sensor (diameter = 3.189 mm) to measure thermal conductivity of a coupled identical samples at constant temperature in which this sensor should be sandwich between them. the obtained data will be analy special software to show thermal conductivity. the measurements are done for pure wax and also for wax with rings of two types and different volumetric percentages. the obtained results ar plotted in figure (5). fig. 4. hot disk device with its sensor. hot disk s hot al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 64 (b) rings manufacturing procedure. b. 3d drawing of two types lessing rings. conductivity measurements due to the importance of this property in this field of study, thermal conductivity had been measured by making use of hot disk thermal constants analyzer (model tps 500) which shown ). this device is make measurement different materials types. it make use of a mica disk sensor (diameter = 3.189 mm) to measure thermal conductivity of a at constant temperature in which this sensor should be sandwich between them. the obtained data will be analyzed by special software to show thermal conductivity. the measurements are done for pure wax and also for wax with rings of two types and different volumetric percentages. the obtained results are . hot disk device with its sensor. 3. experimental equations a. phase change material side heat storage: the form of storing heat in pcm side mainly as a latent heat. the storage capacity can be calculated from: q=� m � .cps . dt+ m . am = m[cp� �t� � t���������+a� . ∆���� the second term of equation (1) represents the amount of heat that phase change occurs during it, which means the required heat for transformation from solid to liquid and vice fig. 5. measured thermal conductivity vs. volume% 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0 0.5 1 1.5 t h e rm a l co n d u ct iv it y , k ( w /m .° c ) volumetric persantages, % hot disk sensor hot disk device 0.5 cm lessing rings 1 sensible heat latent heat khwarizmi engineering journal, vol. 11, no. 4, p.p. 6072(2015) types lessing rings. equations change material side the form of storing heat in pcm side mainly as a latent heat. the storage capacity m . ∆hm + � m � . cpl . dt � ∆h�����+cp� �t� – t����������� …(1) the second term of equation (1) represents the amount of heat that phase change occurs during it, which means the required heat for transformation from solid to liquid and vice versa. . measured thermal conductivity vs. volume%. 2 2.5 3 3.5 volumetric persantages, % lessing rings d=1cm lessing rings d=0.5 1 cm lessing rings sensible heat latent heat rafa a.h albaldawi al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 6072(2015) 65 conduction heat transfer: the transfer of heat inside the pcm occurs due to conduction between its particles, in which it is occurring from the upper surface of pcm to the lower surface of pcm. the fourier's law for heat conduction is expressed as: q = kpcm a ∆ ∆ …(2) 3.2. air side the following equations were used to calculate mass flow rate, nusselt number, reynold number, convection heat transfer coefficient and extracted heat. the experimental data includes the measured velocities and thermocouples readings. air thermo physical properties were taken at bulk mean air temperature as; tb = !� " � …(3) mass flow rate: the mass flow rate can be calculated as follow: ma = ρa va ac …(4) extracted power: the heat transfer from the hot surface to the moving air can be calculated experimentally from: q = ma cpa (to-ti) …(5) convection heat transfer coefficient: convection process is occurred between the hot copper plate and the air flowing beneath it. it was considered to be constant along the duct length, which can be calculated from: h = # $�� %� &� …(6) reynold number: it can be calculated from: re = ρ' (' )* µ' …(7) where; dh can be calculated from dh = + �,∗ .� ��,�.� …(8) nusselt number: the following equation used to calculate it: nu = / )* 0' …(9) 4. results and discussion in this work, a study was done to investigate the effect of using copper lessing rings mixed with an organic pcm (paraffin wax grade b), in which the melting and solidification time was changed. figure (6) illustrate the storage region (pink area) and releasing region (white area) of paraffin wax (grade b). these data was recorded for the midpoint of wax. from this figure, the transition from solid zone to mushy zone (phase change) and then to liquid zone was represented. at beginning, the heat is store in wax as sensible heat in which the increasing in temperature molecules cause an increase in its oscillation and that lead to increment its kinetic energy. this is occurs during solid zone. but then when the temperature of wax reaching the melting or phase changes temperature, the stored heat was as latent heat for this period. commonly, the phase change temperature (melting process) is not as a single point, but it is occurring during ranges of temperature. this is because pcm consist of more than one component (not pure material) and that make it have a range of melting temperature. this range depending on the components' melting temperatures that pcm contain. for this paraffin grade, the phase change occurred during a range of (62-68) °c. after the complete melting, the storing of heat was being as a sensible heat again. but the question is why the latent heat storage period has little or no change in temperature in spite of the applied heat source? the answer for this is that during sensible heat period the increase in temperature makes an increasing in molecule kinetic energy which causes an increase in temperature until reaching the melting point or range. then through melting range period, there will be no or little increase in temperature because the coming heat for molecules will be as a potential energy. the same previous processes would be repeated inversely through solidification process (heat releasing period). rafa a.h albaldawi fig. 6. heat storage and released for paraffin wax midpoint. the heat storage occurred with constant heater temperature of 100°c. the heat released happened with 2.5 m/s air velocity. it can be seen from figure (7) and ( did the lower copper plate temperature (tc6) shift up with time during melting process in cases of pure wax and wax with addition ( of 0.5, 1 cm diameter respectively). the heat applied from heater to pcm upper surface about 150 w and with constant temperature of 100°c. in each case three volumetric percentages of rings have been tested. it is clear that the time required for complete wax melting with 3%, 6% and 10% volumetric percentages compared with pure wax have been decreased up to 1.13, 2.61 and 5.47 times respectively for 0.5 cm rings. while for the case of 1 cm diameter rings the reduction was up to 3.13, 3.39 and 3.94 times respectively with the same previous percentages. that is the best enhancement method occurred with 0.5 diameter lessing rings with 10% volume percent; this is due to its perfect distribution through pcm in which maximum contact between wax and rings occurred. also, the lower rings diameters increased wax areas in contact with copper rings walls and the maximum volume rings percent make better increase in the whole mixture thermal conductivity, while for the same rings diameter (0.5 cm) and lower volume percent, the enhancement process was the weaker and the 3% percent rings with 1 cm diameter gave better results than 0.5 cm diameter rings even if the latter had more volume percent (6%), because of the rings number with 3% and 6% percent was insufficient to fill the whole rig and has bad distribution through wax. this causes no direct contact between upper copper plate, rings and 0 10 20 30 40 50 60 70 80 0 200 400 600 t e m p e ra tu re , t ( °c ) time, t (min) heat storage period phase chang e zone liquid phase zone solid phas e zone * al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 66 . heat storage and released for paraffin wax occurred with constant heater temperature of 100°c. the heat released ) and (8) that how did the lower copper plate temperature (tc6) shift up with time during melting process in cases addition ( lessing rings of 0.5, 1 cm diameter respectively). the heat applied from heater to pcm upper surface about and with constant temperature of 100°c. in each case three volumetric percentages of rings have been tested. it is clear that the time required for complete wax melting with 3%, 6% and 10% volumetric percentages compared with pure wax p to 1.13, 2.61 and 5.47 times respectively for 0.5 cm rings. while for the case of 1 cm diameter rings the reduction was up to 3.13, 3.39 and 3.94 times respectively with the same previous percentages. that is the best enhancement method occurred with 0.5 cm diameter lessing rings with 10% volume percent; this is due to its perfect distribution through pcm in which maximum contact between wax and rings occurred. also, the lower rings diameters increased wax areas in contact with copper rings maximum volume rings percent make better increase in the whole mixture thermal conductivity, while for the same rings diameter (0.5 cm) and lower volume percent, the enhancement process was the weaker and the 3% percent rings with 1 cm diameter gave better results than 0.5 cm diameter rings even if the latter had more volume percent (6%), because of the rings number with 3% and 6% percent was insufficient to fill the whole rig and has bad distribution through wax. this causes no direct copper plate, rings and lower copper plate. therefore; low conduction heat transfer occurred in these two cases. that made it need more time for storing heat. in figures (9) and (10 paraffin middle point plotted during melting and solidification processes. the obtained data shows that the time required for melting and solidification, when rings inserted in wax, is minimized. it is obvious that the maximum reduction in solidification time was occurred with the case of 0.5 cm diameter ri volume percent. but it is clear that melting process is more affected by this addition than solidification process. this is due to no enhancement in heat transfer in air side which cause low heat transfer. so that, heat lost from the lower plate slowly, which make pcm lose heat slowly too. also for higher rings percentages, lower time for charging and discharging processes are reported. the measured temperatures changes with time during melting for five points through pcm axial center line and another one at the lower coppe plate are shown in figures (11) and (12 cases of 0.5 and 1 cm diameter rings respectively, with 10% volume percentages for each. as clear in these two figures, the midpoint (tc3) is melt faster than other points. th was the furthest point from the pcm rig walls and that make it the furthest point from the surrounding in spite of the used insulation, so that more heat would be stored at this region. the lower pcm point (tc6) which is near the lo copper plate was melt slower than other points due to the largest distance between it and the heat source at the upper surface of pcm and that make it need more time to melt completely. the data got from the outlet air temperature for an hour during heat releasing for both rings diameter cases are shown in figures (13) and (14 with 2.5 m/s entrance air velocity after the heat storing from heater with 150 w. it can be seen that the higher volume percent, the higher outlet temperature. also the upmost o is got with the case of 0.5 cm diameter lessing rings with maximum volume percent due to increasing in pcm thermal conductivity by this addition. the curves show that t increased to peak and then decreased gradually. that is because the lower temperature decreased with time during air flow beneath it. 800 1000 pure paraffin phase change period heat released period * khwarizmi engineering journal, vol. 11, no. 4, p.p. 6072(2015) lower copper plate. therefore; low conduction heat transfer occurred in these two cases. that made it need more time for storing heat. 9) and (10), the behavior of paraffin middle point plotted during melting and idification processes. the obtained data shows that the time required for melting and solidification, when rings inserted in wax, is minimized. it is obvious that the maximum reduction in solidification time was occurred with the case of 0.5 cm diameter rings with 10% volume percent. but it is clear that melting process is more affected by this addition than solidification process. this is due to no enhancement in heat transfer in air side which cause low heat transfer. so that, heat lost from the te slowly, which make pcm lose heat slowly too. also for higher rings percentages, lower time for charging and discharging the measured temperatures changes with time during melting for five points through pcm axial another one at the lower copper plate are shown in figures (11) and (12) for the cases of 0.5 and 1 cm diameter rings respectively, with 10% volume percentages for each. as clear in these two figures, the midpoint (tc3) is melt faster than other points. that was first because it was the furthest point from the pcm rig walls and that make it the furthest point from the surrounding in spite of the used insulation, so that more heat would be stored at this region. the lower pcm point (tc6) which is near the lower copper plate was melt slower than other points due to the largest distance between it and the heat source at the upper surface of pcm and that make it need more time to melt completely. the data got from the outlet air temperature at releasing for both rings r cases are shown in figures (13) and (14) with 2.5 m/s entrance air velocity after the heat storing from heater with 150 w. it can be seen that the higher volume percent, the higher outlet temperature. also the upmost outlet temperature is got with the case of 0.5 cm diameter lessing rings with maximum volume percent due to increasing in pcm thermal conductivity by this addition. the curves show that tout values increased to peak and then decreased gradually. ause the lower copper plate temperature decreased with time during air flow rafa a.h albaldawi al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 6072(2015) 67 fig. 7. temperature of the lower point of paraffin wax variation vs. time during melting process for case of 0.5 cm diameter rings with different volume percent compared with the case of pure paraffin. fig. 8. temperature of the lower point of paraffin wax variation vs. time during melting process for case of 1 cm diameter rings with different volume percent compared with the case of pure paraffin. fig. 9. change in temperature of mid pcm point during melting and solidification with lessing rings of d=0.5cm compared with the case of pure wax. the solidification process was done at v = 2.5m/s. fig. 10. change in temperature of mid pcm point during melting and solidification with lessing rings of d=1cm compared with case of pure wax. the solidification process was done at v= 2.5 m/s. 0 10 20 30 40 50 60 70 0 100 200 300 400 500 600 t e m p e ra tu re , t ( °c ) time, t (min) 3% rings d=0.5cm 6% rings d=0.5cm 10% rings d=0.5cm 0 10 20 30 40 50 60 70 0 100 200 300 400 500 600 t e m p e ra tu re ,t ( °c ) time, t (min) 3% rings d=1cm 6% rings d=1cm 10% rings d=1cm 0 10 20 30 40 50 60 70 80 0 200 400 600 800 1000 1200 t e m p e ra tu re , t ( °c ) time, t (min) 3% rings d=0.5cm 6% rings d=0.5cm 10% rings d=0.5cm pure paraffin (no rings) tmelt tsolid* tmelt 0 10 20 30 40 50 60 70 80 0 200 400 600 800 1000 1200 t e m p e ra tu re , t ( °c ) time, t (min) ring 3% d=1cm 6% rings d=1cm ring 10% d=1cm pure paraffin (no rings) tmelt tsolid* tmelt rafa a.h albaldawi al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 6072(2015) 68 in figures (15) and (16) the outlet air temperature vs. one hour time was plotted for four velocities and 10% volume percentages for both rings cases. it is clarified from these figures that the minimal used velocity (v = 1m/s) gave maximum outlet temperature and also that is occurred with the case of 0.5 cm lessing rings. that is because with lower velocity the flowing air would had more time to flow over the seperated plate and that made it able to have more heat exchange. also, at 10% volume percent, the transfer of heat in pcm side is more (higher thermal conductivity) which make the released heat in pcm and heat exchange from the lower copper plate are faster. so that the maximum increase in outlet temperature was up to 2.2 °c compared with pure wax case. the calculated nusselt number for both addition types for an hour was plotted as an average values which represented in figures (17) and (18) as a relationship with reynold number. the higher nusselt number was occurred with the case of 0.5 cm rings, maximum volume percent and maximum used velocity; this was because of the significant increase in heat transfer rate for that case. also the same previous case gave maximum extracted heat as in figs. (19) and (20) and maximum convection heat transfer coefficient as in figures (21) and (22). the extracted heat and convection heat transfer coefficient are plotted vs. the used velocities which show a rise in their values as the velocities augmented. fig. 11. temperature distribution for different points through pcm with addition of 0.5 cm diameter lessing rings during charging process. fig. 12. temperature distribution for different points through pcm with addition of 1 cm diameter lessing rings during charging process. fig. 13. outlet air temperature for v=2.5 m/s in cases of lessing rings d=0.5 cm in pcm side compared with the case of pure paraffin. fig. 14. outlet air temperature for v=2.5 m/s in cases of lessing rings d=1 cm in pcm side compared with the case of pure paraffin. 20 30 40 50 60 70 80 0 20 40 60 80 100 120 t e m p e ra tu re , t ( °c ) time, t (min) tc 1 tc 2 20 30 40 50 60 70 80 0 20 40 60 80 100 120 140 160 t e m p e ra tu re , t ( °c ) time, t (min) tc 1 tc 2 tc 3 24 25 26 27 28 29 30 31 0 10 20 30 40 50 60 70 t e m p e ra tu re , t ( °c ) time, t (min) pure paraffin (no rings) 3% rings d=0.5 6% rings d=0.5 cm 10% rings d=0.5cm 24 25 26 27 28 29 30 31 0 10 20 30 40 50 60 70 t e m p e ra tu re , t ( °c ) time, t (min) pure paraffin (no rings) 3% rings d=1cm 6% rings d=1cm 10% rings d=1cm tc1 tc2 tc3 tc4 tc5 tc6 pcm side air side tc1 tc2 tc3 tc4 tc5 tc6 pcm side air side rafa a.h albaldawi al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 6072(2015) 69 fig. 15. outlet temperature of air with different velocities for case of the addition of rings d=0.5 cm with 10% volume percent compared with pure paraffin case at 2.5 m/s velocity. fig. 16. outlet temperature of air with different velocities for case of the addition of rings d=1 cm with 10% volume percent compared with pure paraffin case at 2.5 m/s velocity. fig. 17. relation between nusselt and reynolds numbers for different volume percent of lessing rings d=0.5 cm compared with pure paraffin case. fig. 18. relation between nusselt and reynolds numbers for different volume percent of lessing rings d=1 cm compared with pure paraffin case. fig. 19. relation between extracted heat and velocities for lessing rings d=0.5 cm compared with pure wax. fig. 20. relation between extracted heat and velocities for lessing rings d=1 cm compared with pure wax. 24 25 26 27 28 29 30 31 32 0 10 20 30 40 50 60 t e m p e ra tu re , t ( °c ) time, t (min) 10% rings v = 1 10% rings v = 2 10% rings v = 2.5 10% rings v = 3 pure paraffin v=2.5 24 25 26 27 28 29 30 31 0 10 20 30 40 50 60 t e m p e ra tu re , t ( °c ) time, t (min) 10% rings v = 1 10% rings v = 2 10% rings v = 2.5 10% rings v = 3 pure paraffin v=2.5 0 50 100 150 200 250 2000 4000 6000 8000 10000 12000 14000 n u ss e lt n u m b e r, n u reynolds number, re pure paraffin (no rings) 3% rings d=0.5 cm 6% rings d=0.5cm 10% rings d=0.5cm 0 50 100 150 200 250 2000 4000 6000 8000 10000 12000 14000 n u ss e lt n u m b e r, n u reynoleds number, re pure paraffine (no rings) 3% rings d=1cm 6% rings d=1cm 10% rings d=1cm 0 10 20 30 40 50 60 70 80 90 100 0 0.5 1 1.5 2 2.5 3 3.5 e x tr a ct e d h e a t, q ( w ) velocity, v (m/s) pure paraffin (no rings) 3% rings d=0.5cm 6% rings d=0.5cm 10% rings d=0.5cm 0 10 20 30 40 50 60 70 80 90 100 0 0.5 1 1.5 2 2.5 3 3.5 e x tr a ct e d h e a t, q ( w ) velocity, v (m/s) pure paraffin (no rings) 3% rings d=1cm 6% rings d=1cm 10% rings d=1cm rafa a.h albaldawi al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 6072(2015) 70 fig. 21. calculated convection heat transfer coefficient vs. velocities of air for lessing rings d=0.5 cm compared with pure wax case. fig. 22. calculated convection heat transfer coefficient vs. velocities of air for lessing rings d=1 cm compared with pure wax case. 5. conclusion in this work, thermal conductivity and heat transfer for paraffin wax had been enhanced for the purpose of improving charging and discharging processes. the study of conductivity enhancement was conducted using two different lessing rings diameters with three volumetric percentages at four different air velocities studied. the following conclusions can be extracted from the discussion of the obtained results: • the addition of high thermal conductive lessing rings reduced the time required for melting. which cause an increase in whole thermal conductivity of paraffin/rings mixture. so that, the higher volume percent, the lower charging time. • the rings with 1cm diameter gave better results in charging and discharging process than the rings with 0.5 cm diameter in cases of 3% and 6% volume percent. because of the latter rings did not fill the whole wax rig with these percent and there was an amount of wax still had no rings among it especially at the upper portion of pcm. that is 3% rings of 1cm are more effective and economic than the 6% rings of 0.5cm. • the minimum recorded time of melting and solidification processes was happened in case of 0.5 cm diameter rings with maximum volume percent (10%) in which the enhancement process reached up to 5.47 times as compared with case of pure paraffin through melting process. this was occurred due to good distribution of these • rings type through pcm with this percent. • the solidification time was enhanced but not like what occurred during melting when rings added. the minimum recorded time for wax solidification was occurred with the same case as in melting and with maximum used inlet air velocity (v = 3 m/s). • the outlet air temperature did not increased a lot when rings added. the maximum increasing obtained for case of inserting 0.5 cm diameter rings, maximum volume percent and minimum entrance air velocity. • at lower velocity, higher outlet temperature obtained. but with maximum velocities; a gain in heat transfer rate was acquired especially in the initial period of cooling which resulted in minimum time required for solidification. • the calculated nusselt number, power extracted and convection heat transfer coefficient were also improved by these additions. and all of them got maximum values with maximum velocity. • finally; this enhancement method can be considered as an economic method. because the manufacturing process of these rings was so easy (manufactured by a manual mold). also the added amount of enhancers is not very much (maximum 10%) which need low cost, while the enhancement magnitude was high. nomenclature am the fraction melted ac crosses sectional area, m2 as surface area, m2 cpa specific heat of air, j/kg.˚c cpl average specific heat between tm and t2 for pcm, j/kg.˚c cps average specific heat between t1 and tm for pcm, j/kg.˚c 0 20 40 60 80 100 120 0 0.5 1 1.5 2 2.5 3 3.5 c o n v e ct io n h e a t tr a n sf e r co e ff e ci e n t, h (w /m 2 .° c ) velocity, v (m/s) pure paraffin (no rings) 3% rings d=0.5cm 6% rings d=0.5cm 10% rings d=0.5cm 0 20 40 60 80 100 120 0 0.5 1 1.5 2 2.5 3 3.5 c o n v e ct io n h e a t tr a n sf e r co e ff e ci e n t, h (w /m 2 .° c ) velocity, v (m/s) pure paraffin (no rings) 3% rings d=1cm 6% rings d=1cm rafa a.h albaldawi al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 6072(2015) 71 d lessing ring diameter, cm dh hydraulic diameter, m h convection heat transfer coefficient of air, w/m2.˚c ∆ hm heat of fusion of pcm, j/kg h height, mm ka thermal conductivity of air, w/m.˚c kpcm thermal conductivity of pcm, w/m.˚c l length, mm m mass of pcm, kg ma mass of air, kg mpcm mass of pcm, kg nu nusselt number, dimensionless q extracted heat, w re reynolds number t time, minute t temperature, ˚c ∆t temperature difference between the upper and lower point of pcm, ˚c tb bulk temperature of air, ˚c tc thermocouple ti inlet air temperature, ˚c tm melting temperature of the storage material, ˚c tmid middle temperature of the storage material, ˚c to outlet air temperature, ˚c ts surface temperature, ˚c t1 initial temperature of the storage material, ˚c t2 final temperature of the storage material, ˚c va velocity of air, m/s w width, mm ∆x distance between the upper and the lower point of pcm, m greek symbols µa dynamic viscosity of air, kg/m.s. ρa density of air, kg/m3. ρl density of liquid pcm, kg/m3. ρs density of solid pcm, kg/m3. acknowledgment the authors of this paper are grateful to the staff of mechanical engineering department in almustansiriya university for their help and support in providing some of the devices that required for completing this work. 6. references [1] sharma, a., tyagi, v.v., chen, c.r. and buddhi, d., 2009, review on thermal energy storage with phase change materials and applications, renewable and sustainable energy review, 13, pp. 318-345. [2] tian, y., 2012, heat transfer enhancement in phase change materials (pcms) by metal foams and cascaded thermal energy storage, phd thesis, university of warwick. [3] molefi, j. a., 2008, investigation of phase change conducting materials prepared from polyethylenes, paraffin waxes and copper, phd thesis, university of the free state. [4] abhat, a., 1983, low temperature latent heat thermal energy storage: heat storage materials, solar energy, 10(4), pp. 313-332. [5] vadwala, p. h., 2011, thermal energy storage in copper foams filled with paraffin wax, m.sc. thesis, university of toronto. [6] lamberg, p. and sir'en, k., 2003, approximate analytical model for solidification in a finite pcm storage with internal fins, applied mathematical modelling, 27, pp. 491–513. [7] velraj, r., seeniraj, r. v., hafner, b., faber, c. and schwarzer, k., 1999, heat transfer enhancement in a latent heat storage system, solar energy, 65(3), pp. 171-180. [8] zhao, c. y., lu, w. and tian, y., 2010, heat transfer enhancement for thermal energy storage using metal foams embedded within phase change materials (pcms), solar energy, 84(8), pp. 1402-1412. [9] suresh, s., selvakumar, p., salyan, s. and sriram, v., 2013, experimental investigation of pcm-based heat sink with different configurations of internal fins, international conference on advance research in mechanical , aeronautical and civil. [10] castell, a., solé, c., medrano, m., roca, j., garcía, d. and cabeza, l. f., effect of using external vertical fins in phase change material modules for domestic hot water tanks. [11] mettawee, e. b. s. and assassab, g. m. r., 2007, thermal conductivity enhancement in latent heat storage system, solar energy, 81(7), pp. 839–845. [12] sanusi, o., warzoha, r. and fleischer, a. s., 2011, energy storage and solidification of paraffin phase change material embedded with graphite nanofibers, international journal of heat and mass transfer, (54), pp. 4429–4436. [13] fedden, a. d., 2006, graphitized carbon foam with phase change material, m.sc. thesis, air university. � )2015( 6072، =>;. 4، ا-19د111+*. ا-67ارز(4 ا-0123/. ا-,+*(را&% $#"س � 72 ��ت ����� ا������� �� ��دة �����ة ا���ر �� اداء ������ ��درا�� �$��� �� #"!�� اد �ل 'ن ��اري **ا��0 ��0 /��ع *را��*�س ��+ ا�*�(اوي �$�(ي +�� ***�1ن ��$( ا-+"(9. ا-,�b / .cde2f*/. ا-a /.0123�@ ا-0123. ا-,/<"?/</. ***، **، * rafa_a70@yahoo.com: ا-#1cd اdf>-hو?4 * aseelkshyaaa@yahoo.com: ا-#1cd اdf>-hو?4 ** *** 1cd#-و?4 اdf>-hا: b.hammendy@yahoo.com ا��234 � (lx<*. ا3le?h"ر ، . ا-;dlارة ا-<"(l0.l2"طا-,6اد ا-,d/vfة ا-6uر وا 1ة (� اdlsb ا-,6lاد ا-,17fl0r.#l0"2ام &l)6p2) 4l"ت ا-nl7ن ا-;dlاري 6j ت19l>� -z3ه ا-,6اد /[/u#-د ا",+?h6ادواl,-ه اzl3.lcارd;-ا-67اص ا �� $*[ b/>/. ت;�//s "#-ا �) 1c19-ا n/bd9^ ت_ . �/l�;1رس تlc `l;#-ا اzlن ھbl& c#l�-ا اzl3� ت,e* .&"fbj g"ت -/�d2 ا-2;"0/. -*,"دة ا-,d/vfة ا-6uر . ا-,6=*/. ا-;dارc. -,"دة (d/vfة ا-6uر/�;f-ا ./*,$)�ت,gl دراl0. تlh .( dlua d/ibl,% ا-#l"را&/ � ا-;cdua 17امf0bj ./0";2-ت ا"e*)cm و ١cm ٠.٥ .( .&"ln,-ت ا"e*;-ا �) ./,+ c�? ثri .0درا g,ت dua ^>p-zb)ان %). ١٠و % ٦، %٣ "l,b � ا3le?h". $,*/. ا-dcd<f ت,g (% اft#"ر ارd0 %jع -<^ "-.l)ز gl**a ت"le*;-ا �l) .l/,+ .#l�? dl#bان ا gl2/j "l3/*$ 6لe;-4 ت@ اf-ا vw"f2-ر وزادت ان ا � ا?ef"ل ا-;dارة &4 )^b %,lx*ت"le* .&"lf6د اl_1م وl$ .-" %) xf?ر"e) @ا-63اء اذا (" ت c?"_6ر وu-ة اd/vf,-ا-,"دة ا c?"_ �� ھzlه ا-;*le"ت lb"ن ، (l>c*ef-ا �% ٣(#. ا-;+,/lfh .l"&. ا-;*le"ت ت@ ا-6=6ل ا-[ اa^ ز(� hزم -3e?r"ر gl?"b ")12$ ا-2�cm) l (1-;"-. ا-;*e"ت duej . -3" تd/ib اa^ $*[ ز( � (% *e"ت <? duej�e) "3"ر?. 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(% ا"e))1cm ( و-.ej"�-#. ا�3" *2�<? . .$dl0 ^laان ا .lp r) �l>,,-ا �l) p-zb)v = 1 m/s ( ارةdl 1ر_"تl.l,/a ]l*$ا glu$ا .)v= 3m/s($12 ا$*[ d0$. ت;e} اa^ ز(� -r?+,"د j/2," ، ا-63اء ا-7"ر_. 47-53 al-khwarizmi engineering journal,vol. 11, no. 3, p.p. morphology and mechanical properties of (epoxy/pvc) blend awham m. hameed muaed f. *,*** department ** mechanical department (received abstract in this research, the morphology and mechanical properties of blend was prepared by manual mixing of epoxy resin with different weig dissolving it in cyclohexanon). five sheets of polymer blends were prepared at room temperature. tests were carried out to study s compared with the properties of pure epoxy. the morphology o compatibility nature between the two polymers under work. this percentage gave the highest value of tensile strength compared with other percentages of mixing for (ep/pvc) blends. keywords: epoxy, pvc, polymer blend, mechanical properties, morphology. 1. introduction an epoxy resin is a polymer containing two or more epoxy group rings. such groups can be terminal, internal or cyclic structures. they can bond with other molecules, forming a large three dimensional network. the most used hardeners are aromatic and aliphatic amine as well as anhydride hardeners. all should be added into the epoxy resin with adequate weight ratio to cross-linking [1]. a lower crosslink density can toughness by permitting greater elongation before break. a higher crosslink density can give a higher glass transition temperature and improved resistance to chemical attack. recently, rubber toughened epoxy resins have gained signif in interest. small rubber particles scattered in the epoxy resin are believed to improve the fracture toughness of the neat resin [2]. polymer blends and alloys have received widespread attention for the last several khwarizmi engineering journal,vol. 11, no. 3, p.p. 47-53 (2015) morphology and mechanical properties of (epoxy/pvc) blend awham m. hameed* entihaa g. daway muaed f. abdal majed*** department of applied sciences/ university of technology mechanical department/ kut technical institute/ kut * email:awham_m@yahoo.com ** email:entihaa.gatea@yahoo.com ***email:moaedfaik@yahoo.com (received 16 september 2014; accepted 13 april 2015) in this research, the morphology and mechanical properties of (epoxy/pvc) blend were investigated. mixing of epoxy resin with different weight ratios of (poly vinyl chloride ( five sheets of polymer blends in wt% included (0%, 5%, 10%, 15% and 20%) of pvc ests were carried out to study some mechanical properties for these blends and compared with the properties of pure epoxy. the morphology of the prepared materials was compatibility nature between the two polymers under work. it was found that the best ratio of addition is (20%) of pvc. the highest value of tensile strength compared with other percentages of mixing for (ep/pvc) polymer blend, mechanical properties, morphology. an epoxy resin is a polymer containing two or group rings. such groups can be terminal, internal or cyclic structures. they can molecules, forming a large threedimensional network. the most used hardeners are aromatic and aliphatic amine as well as hardeners. all should be added into the epoxy resin with adequate weight ratio to provide nk density can improve toughness by permitting greater elongation before density can give a higher glass transition temperature and improved recently, rubber toughened epoxy resins have gained significantly in interest. small rubber particles scattered in the epoxy resin are believed to improve the fracture polymer blends and alloys have received widespread attention for the last several decades. polymer blends are defined as physical mixture of two or more polymers. they may be divided into different categories: miscible blends in which the components exist in a simple homogeneous phase and immiscible ones in which the exist in two distinct separated phases. the former ones offer various advantages over the latter. the origin of miscibility between the polymer pairs has been understood based on theoretical background and experimental results [3]. nowadays, polymer blending ha useful method for improving or modifying the physicochemical properties of polymer materials. an important property for the polymer blend is the miscibility of its ingredients, as it affects the mechanical properties, the morphology, the permeability, and the degradation previous study used h prepare sheets of unsaturated polyester/poly chloride (upe/pvc) blends with different weight percentages of pvc (10%, al-khwarizmi engineering journal (2015) morphology and mechanical properties of (epoxy/pvc) blend daway** blend were investigated. (ep/pvc) ht ratios of (poly vinyl chloride (pvc) after (0%, 5%, 10%, 15% and 20%) of pvc ome mechanical properties for these blends and f the prepared materials was examined to study the tio of addition is (20%) of pvc. the highest value of tensile strength compared with other percentages of mixing for (ep/pvc) ined as physical mixture of they may be divided into different categories: miscible blends in which the components exist in a simple homogeneous phase and immiscible ones in which the components exist in two distinct separated phases. generally, various advantages over the latter. the origin of miscibility between the has been understood based on ground and experimental results polymer blending has been a most improving or modifying the physicochemical properties of polymer materials. an important property for the polymer blend is the miscibility of its ingredients, as it affects the mechanical properties, the morphology, the eability, and the degradation [4]. hand lay-up method to unsaturated polyester/poly vinyl blends with different weight (10%, 20% and 30%). awham m. hameed al-khwarizmi engineering journal, vol. 11, no. 3, p.p. 4753 (2015) 48 results show increasing in the values of maximum stresses, yield stresses and modulus of elasticity for upe/pvc blends with increasing the weight percentage of the polyvinyl chloride (pvc). upe/pvc blends reinforced with one layer of glass fiber results showed good mechanical properties for the composite which contain 20% pvc. also the results show that composites reinforced with two layers of glass fiber randomly increasing in values of maximum stresses with increasing pvc percentage [5]. morphology studies and mechanical properties for polystyrene / styrene-butadiene-styrene (ps/sbs) blends were performed on the blends of polystyrene (ps) and styrene-butadiene-styrene (sbs) prepared in different ratios by melt blending technique using haake polydriver extruder. tensile test, differential scanning calorimetry (dsc) and scanning electron microscopy (sem) were used to study the mechanical and thermal properties and morphology [6]. the main objective of the present work is study the morphology and extent of modification of epoxy properties by blending it with (pvc). for this purpose, a series of blends with various weight ratios of (pvc) has been prepared. the effect of addition ratio of (pvc) on the morphology and mechanical properties of epoxy resin was investigated and the role of (pvc) as a plasticizer has been discussed. 2. experimental binary polymer blend was prepared by mixing of epoxy resin (type quickmast 105) with polyvinylchloride (pvc) after dissolving (5gm) of it with (100ml) of cyclohexanon solvent. degree of polymerization of pvc ranges commercially from 625 to 2700. hand lay-up method was used to prepare the molds of blend with different weight ratios (wt%) of pvc. it is important to remember that (pvc) powder was sieved by using sieve (type retsch) produced by uk company. the particle size of pvc ranged from 25 to 63 micron. pvc powder in all particle sizes were dissolved into cyclohexanon container. five sheets of polymer blends with different wt% (0%, 5%, 10%, 15% and 20%) of pvc were prepared in this work. the molding process was carried out by using five polymer sheets (transparent paper) prepared with dimension (20×15×2) cm3. these casted sheets were left inside the molds at room temperature for (24hours) and then removed from the molds after completing the solidification process; the casts were put into oven with (50oc) for (1 hour) to complete the curing process. the homogeneity case of these blends was tested by using optical microscope. it is important to show that the mixing process with higher ratios of pvc were performed too, it is found that the cast become more ductile and difficult for handling with it to remove it from the mould. the density of the prepared blends was determined from the equation [7]: ρ� = x�ρ� + � ρ ... (1) where ρ� : the density of the matrix (polymer blends). ρ1, ρ2 : the density of the polymers in the mixture x1, x2: the percentage of the polymers in the mixture. according to the standard specifications (astm-d638, astm-d695 and astm-d790), the samples of tensile, compression and flexural tests were cut respectively. the roughness test were carried out on small samples with dimensions (2×2×0.5) cm3 for epoxy and its blends. all these tests were performed at room temperature and repeated three times for each sample and the average of values were determined. optical microscope type (bel, made in italy, model mtm-1a) was used to investigate the morphology of pure and blends specimens. tensile properties were measured by an instron universal testing machine supplied by chinese company, model 1195. the crosshead load was at (5kn) and a speed of (5mm/min). the hydraulic press type ( leybold harris, germany, model 36110) was used for both compression and flexural tests. the values of tensile and compressive strengths were determined directly from the corresponding instruments. flexural strength (f.s) and shear stress values were calculated from the flexural strength test by applying the following equations [8]: . � = 3�� 2�� � … (2) �ℎ��� ������ = 3� 4��� … (3) where p: is the required load to break the specimen. s: span (is the distance between the two supported points of the sample) (mm). b: is the width of specimen (mm). t: is the thickness of specimen (mm). awham m. hameed al-khwarizmi engineering journal, vol. 11, no. 3, p.p. 4753 (2015) 49 3. results and discussion figure (1) illustrates the optical micrographs of the morphology for epoxy and its blends with different percentages of (pvc). it is clear that the best ratio which gives the better miscibility between the two polymers is (20 wt.%) while the nature of morphology for the surfaces of samples with lower wt.% exhibits unsmooth surfaces with less homogeneity. figure (2) shows the values of tensile strength as a function of weight ratios of (pvc). from this figure, it can be noticed that these values decrease with increasing (pvc %) at the first ratios of blending but return to increase at the 20% of (pvc). the reason behind this phenomenon may be related to the best homogeneity state between the two polymers at this ratio of mixing because of epoxy and pvc form as a single phase material as shown in fig.(1e). in other words, the mixing ratio (15%) has the lowest value of tensile strength. there was probably no significant interaction between the modifier (pvc) and epoxy with below a modifier concentration of (20%). this result agrees with that of the study reported by bhuniya and adhikari [9]. it is necessary to mention that chiang [10] reported that the properties of blend strongly depend on the morphology, that is, on miscibility, size and form of dispersed phase, character and size of the interphase domain. figure (3) shows the effect of weight percentages of (pvc) on the compressive strength values for (ep/pvc) polymer blend. it is also being noticed that compressive strength of epoxy decreases after blending it with (pvc). this fact may be attributed to that epoxy is thermoset material while pvc is thermoplastic, therefore when the two polymers were mixed together a semi-interpenetration network is formed which has less rigidity than full interpenetration network [11,12]. for this reason most mechanical properties decrease after blending epoxy with (pvc). it is well known that the stress-strain of polymers divided into two behaviors, the first is named the elastic and the second is named plastic deformation. from this simple definition, it can be noticed that epoxy behaves the elastic behavior with little deformation before fracture as shown in fig.(4) which represents the (stress-strain) relations for epoxy and its blends with different weight ratios of (pvc) under compression loading. it is clear that the behavior of epoxy changes after blending process with pvc where transformed from brittle to ductile or semi-ductile at the ratio (15%). this change can be obvious from the increasing of plastic strain which increased after the blending clearly. the reason for this change comes from the increasing of mobility polymer molecular chains. it also can be noticed that the mixing percentage (20%) has modulus of elasticity higher than that of the ratio (15%) as shown in fig. (5). this behavior may be attributed to the homogeneous physical nature between the two polymers under study at the mixing ratio (20%). this result corresponds with previous study in this field [13]. the reason for increasing of flexural strength and shear stress at (20% content of (pvc) is the same reason as for the increasing in tensile and compressive strengths as shown in the fig.s(6,7). it is clear that the roughness value of epoxy decreases after addition (pvc) that is shown in fig.(8)which illustrates the effect of weight percentages of (pvc) on the roughness values for (ep/pvc) polymer blend. it is important to mention that the roughness of surface depends on the hardness amount of material. so after blending thermo set polymer (epoxy) with thermoplastic polymer (pvc), the hardness will be dropped due to the plasticizing of material. this behavior will be reflected on the values of roughness which decreased after the blending process. after this study, we can obtain on epoxy modified with thermoplastic material by addition pvc. it is well known that epoxy is brittle material deforms under effect of stresses with little elastic strain, but it can transform to material deforms with larger plastic deformation after blending with pvc. it is vital to indicate that there is previous studies about the modification of epoxy with thermoplastic material for increasing the toughness [14, 15], but the current work is interested in study the morphology and mechanical properties of (ep/pvc) blend. awham m. hameed al-khwarizmi engineering journal, vol. 11, no. 3, p.p. 4753 (2015) 50 (a) 0% pvc (b) 5% pvc (c) 10% pvc (d) 15% pvc (e) 20% pvc fig. 1. optical micrographs of the morphology for epoxy and its blends (150x). fig. 2. effect of weight percentages of (pvc) on the tensile strength values for (ep/pvc) polymer blend. fig. 3. effect of weight percentages of (pvc) on the compressive strength values for (ep/pvc) polymer blend. fig. 4.stress-strain curves for epoxy and its polymer blends under compression loading. 0 10 20 30 40 50 60 70 80 0 0.1 0.2 0.3 0.4 epoxy 5% pvc 10% pvc 15% pvc strain st re ss ( m p a) 0 10 20 30 40 50 60 70 80 0 5 10 15 20 25 c om pr es si ve pvc % t en si le s tr en gt h ( m p a) pvc % c om pr es si ve s tr en gt h (m p a) awham m. hameed al-khwarizmi engineering journal, vol. 11, no. 3, p.p. 4753 (2015) 51 fig. 5. effect of weight percentages of (pvc) on the modulus of elasticity values for (ep/pvc) polymer blend. fig. 6. effect of weight percentages of (pvc) on the flexural strength values for (ep/pvc) polymer blend. fig. 7. effect of weight percentages of (pvc) on the shear stress values for (ep/pvc) polymer blend. fig. 8. effect of weight percentages of (pvc) on the roughness values for (ep/pvc) polymer blend. 4. conclusions 1it can be concluded that pvc which is thermoplastic polymer acts a modulating material for the properties of epoxy resin. 2the plastic strain increases obviously after blending epoxy with pvc at the ratio (15%). 3it is found that the percentage (20%) of pvc gives the highest value of tensile strength compared with other percentages of mixing for (ep/pvc) blends. this conclusion is benefit indication for future works in this field. 4we can reach to the results which show that epoxy sustains larger plastic deformations when it exposed for certain stresses, this obtains after mixing it with pvc. 5stress-strain behavior provides further evidence, showing that (pvc) indeed acts as a plasticizer factor for epoxy. 5. references [1] mei li, “temperature and moisture effects on composite materials for wind turbine blades”, msc. thesis, montana state university, 2000. [2] launikitis m.b., “vinyl ester resins, handbook of composites”, lubn g., pp.(3850), 1981. [3] biju p. k., radhakrishnan m. n. , thomas g. v., gopinathan m. r., plasticizing effect of epoxidized natural rubber on pvc/elnr blends prepared by solution blending 0 100 200 300 400 500 600 700 800 0 5 10 15 20 25 pvc % m od ul us o f e la st ic it y (m p a) awham m. hameed al-khwarizmi engineering journal, vol. 11, no. 3, p.p. 4753 (2015) 52 “materials science-poland”, vol. 25, no.4, pp.(919-932), 2007. [4] guoquan z., fagang w., kejing x., qiaochun g., yuying l., study on properties of poly(vinyl alcohol)/polyacrylonitrile blend film, “polímeros”, vol.23, no.2, pp.(146151), 2013. [5] mohamed. k. jawad, kawakib. j. majeed, ekram. a. al-ajaj, tensile strength study of unsaturated polyester /polyvinyl chloride composites reinforced with glass fibers, “iraqi journal of science”, vol.52, no.3, pp.329-334, 2011. [6] buthaina a. ibrahim and karrer m. kadum, morphology studies and mechanical properties for ps/sbs blends, “international journal of engineering & technology ijetijens”,vol.12, no.03, pp.(19-27), 2012. [7] utracki l. a., "polymer alloys and blends, thermodynamics and reology" hanser publishers, new york, (1989). [8] crawford r. j., “plastic engineering”, 3rd edition, elsevier butterworth-heinemann, oxford, (1998). [9] bhuniya s., adhikari b., toughening of epoxy resins by hydroxy-terminated, siliconmodified polyurethane oligomers “journal of applied polymer science”, vol.90, no.6, pp.(1497-1506), 2003. [10] chiang w. y., lo m. s., properties of copolymer-type polyacetal/polyurethane blends “journal of applied polymer science”, vol.36, no.7, pp.(1685-1700), 1988. [11] work w. j., horie k., hess m. and stepto r. “definitions of terms related to polymer blends,composites and multiphase polymeric materials”, vol. 76, no.11, pp. (1985–2007), 2004. [12] walsh d. j. , rostami s., advantages of polymer science, “polymer blends”, vol. 70, pp.(119), 1985. [13] awham m. hameed and nada r. kareem, preparation and characterization of binary polymer blend reinforced with polypropylene, carbon and hybrid fibers, “jordan journal of physics”, vol.7, no.1,. pp.(13-22), 2014. [14] yi l., xinhui z. & yingfeng y., gelation behavior of thermoplastic-modified epoxy systems during polymerization-induced phase separation, “ colloid polymer science ”, 288, pp.(1561–1570), (2010). [15] pearson r. a. and yee a. f.,toughening mechanisms in thermoplastic-modified epoxies: 1. modification using poly(phenylene oxide), “polymer”, vol.34, no.17,. pp.( 3658-3670), 1993. 3، ا���د�11ا���ارز�� ا������ ا������ � أوھ م ���� ������� ،53 -47 )2015( 53 )+��� &��ر)� ا�� )��*/ ا()'�&%�(وا���اص ا���" #�"� ����! ا���ر ����� ***�4)� 23 1'� ا����� **ا#�0 ء & طدواي *أوھ م ���� ���� ����� ا������ ا���������� � *،*** /"! ا����م ا�� +�ت ا�&�() ا����'/ "! ا�&���%�$ ** awham_m@yahoo.com (,-�: ا/���-و%' ا� * entihaa.gatea@yahoo.com : ا��-,) ا/���-و%'** moaedfaik@yahoo.com ***'%ا/���-و (,-�:ا� � ا��5 >�ا0�� ) >��' +��ر,) ا�d��,�e/ ا/,��+!'(و") a -bc��= �@ . ا�&�ر������8 وا�<�اص ا�&���%���� �<��= >���&-ي :��9'8' ھ6ا ا��45 3 درا�0 bc-ت 8' ھ6ه ا�)راa �0&!� و. ���' +��ر,) ا�d��,�e >�) اذا>�g,6� '8 k ا�!�,���ھ�!�%�نا� �)وي �-اi�3 ا/,��+!' �g!% h وز%�� �<���e �@ا�<�= ا� ��رات �)را�0 ا�<�اص ا�&���%���� . �x) در�� c-ارة ا��pvc �8-v@ ال % )٠،٥،١٠،١٥،٢٠(>�!g وز%�� &p�o ا��اح �a/ا @� �x�&�� o,-ا� و") .3 58[ ا�&�ر������8 ��&�اد ا�&b5-ة �v-ض درا�0 ط���� ا���اz8 >�@ ا�����&-,@ "�) ا��45. ���$ ا�<9y= و"�ر%�a h� oاص ا/,��+!' ا���' �3�' ا���&� ا/x�a �&��و�� ا�`) ���ر%� >�!g اa-ى ��<�= �pvc@ ) %20(و�) >�ن ا��!�� ا/y� db8^��8 ھ' �,�b&ا� �� . yxوة x�a ان ھ6ه ا��! 51-61غادة عادل al-khwarizmi engineering journal al-khwarizmi engineering journal,vol. 13, no. 1, p.p. 5161 (2017) simulation model of wind turbine power control system with fuzzy regulation by mamdani and larsen algorithms ghada adel aziz department of electromechanics engineering/ university of technology email: pghadasama@yahoo.com (received 19 june 2016; accepted 22 january 2017) https://doi.org/10.22153/kej.2017.01.003 abstract the aim of this work is to create a power control system for wind turbines based on fuzzy logic. three power control loop was considered including: changing the pitch angle of the blade, changing the length of the blade and turning the nacelle. the stochastic law was given for changes and instant inaccurate assessment of wind conditions changes. two different algorithms were used for fuzzy inference in the control loop, the mamdani and larsen algorithms. these two different algorithms are materialized and developed in this study in matlab-fuzzy logic toolbox which has been practically implemented using necessary intelligent control system in electrical engineering and renewable energy concepts. a comparison was done to access the functionality of the developed power control system of fuzzy logic and classical control system with pid – control. it can be concluded that the power control system of fuzzy logic allows to accurately maintain production under the control target function for each work area. when switching operation of wind turbines, it has the distinction that from 13.5 m/s to another wind velocity value, there is no overshoot and a typical of classical control systems, and when the wind velocity v is less than13.5 m / s, the pitch angle of the blades should be slightly greater than zero, and if it has increased by 5 °, then blade length should be minimal as possible. simulation program proved the possibility of effective power regulation for the large wind turbines controller fuzzy type on the basis of knowledge production "if then" rules, which were shown to be effective on these wind turbines control. keywords: mamdani and larsen algorithms fuzzy inference, matlab fuzzy logic ,fuzzy-pid controllers, wind turbine. 1. introduction the development of wind power, combined with energy conservation measures in the field of wind energy in 2030 will be able to provide 29% of electricity demand in the world, because the statistical view has been showed this forecasting during the last 15 years especially the last one in the global annual installed wind capacity in 2015 has been reached to 63,013 mw.[ 1 ]. in recent years many researchers discuss the characteristics of the wind turbine and focus on the latest advances in wind energy modeling aerodynamic and wind control with methods of nonlinear, fuzzy and forecasting [2]. the aim is to control the angle of the wind turbine blades at different wind speeds and with the set of matlab/ simulink simulation environment software development controller for stable operation. obviously fuzzy pid controller and fuzzy pi controller to produce better than these comparisons after modeling.[3]. design synthesis of the vector control system yawn fuzzy pid controller, system modeling using matlab modeling software, and taking simulation test. comparing the simulation curves with the general pid control and fuzzy pid control section, the result show that the synthesis of a fuzzy pid control system has a high performance stability [4]. pdf created with pdffactory trial version www.pdffactory.com mailto:pghadasama@yahoo.com https://doi.org/10.22153/kej.2017.01.003 http://www.pdffactory.com http://www.pdffactory.com ghada adel aziz al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 5161 (2017) 52 a specific fuzzy controller takes into account both wind speed and errors acceptable correlation to obtain maximum performance efficiency. the turbine is able to maintain its power output around its nominal value, and at the same time maintain its rotation about the vertical axis of the movement system meaningless. careful simulation tests to evaluate the effectiveness of the proposed system [5]. application of the theory of fuzzy sets for control tasks mamdani process in 1975 was carried out for the first time year. mamdani has created a fuzzy controller for controlling the steam generator. currently used in the classical proportional plus integral plus derivative (pid) controllers are still the most widely adopted method in industry for various control applications, due to their simple structure, ease of design, and low cost in implementation, the best, nonlinear and adaptive management. also, fuzzy sets of input and output variables should increase in order to have a better accuracy with more corrective action formulae .[6]. the mamdanitype fis uses the technique of defuzzification of a fuzzy output and has output membership functions, and the mamdani method needs more computation time, and the results have fewer errors, but it is less flexible in system design as compared with others like sugeno method ,because sugeno can be integrated with anfis tool to optimize the output and has no output membership function [7]. the load system is simulated in the matlab/simulink and the performance operated by pi controller and fuzzy logic controllers (flc ) are compared and analyzed with 25-rules base stores the linguistic control rules which required by rule evaluator [8], and the decision making task can be carried on through a fuzzy logic controller optimized algorithm, which able to tune flcs parameters minimizing, at the same time, the number of fuzzy rules may be having three parameters for each triangular mf with three input and one output for the flc, with the fis composed by 27 rules is thus characterized the two fis in the proposed flc, will account for 126 real bounded values and it has got a good performance comparison [9]. a fuzzy inference system may have different shapes like triangular, trapezoidal, gaussian, etc., the effect of membership function is studied and evaluated in the fuzzy logic controller and the performance comparison with a three different types of membership function in fuzzy logic controller [10], and for each membership functions in a fuzzy scale of five linguistic states of triangular type can be mapped into the values of negative “ large (nl), negative small (ns), zero error (ze), positive small (ps) and positive large (pl) with the 5mfs 25 rules” which are formed and applied to the system used [11]. the wind power vestas v27 – 225 is the model wind turbine suggested with a start-up wind speed: 3,5 m/s , nominal wind speed: 14 m/s and maximum wind speed: 25 m/s and the tail is able to turn the head to the wind wheel in the direction of the wind at his rejection at 10-20 °.are its characteristics [12]. 2. the mathematical modulation the mechanical power is calculated by understanding the calculation of the mechanical power through the wind turbines, which the wind energy is transformed to mechanical power then it is converted to electrical power [13] : the force experienced. f=0.5ρav2 …(1) and the rotor torque equation is given by t=0.5ρav2 r …(2) where here r= rotor radius. according to well-known relations aerodynamic moment mp and power pp propeller are uniquely determined by the frequency of rotation n and wind speed v (c considering the pitch angle of the blade) [14]: mp = 0.5 m π r3 ρ v2 …(3) where n= ; ω =z ; pp =mp ω taken in to account the cp is the performance coefficient of the turbine, ρ is the air density (kg/m3), a is the turbine swept area (m2). v is the wind speed (m/s) ,which going to find the mechanical output power of the turbine (w) as [7]: pp = 0.5 ρ cp a v3 …(4) cp ratio determines the efficiency of wind energy depends on the design and the propeller, the rotor speed and wind speed. it is given by: cp = 0.5(z-0.022α2-5.6)e-0.17 z …(5) 2.1. the fuzzy inference mamdani algorithm the rule base when the hypothesis of mutual independence of the variables is based on the rules of many inputs and one the output variable. in the fuzzy inference mamdani algorithm , the rules are as follows [15]: if has and has and has , then y has , i= 1,2,3,…….n …(6) pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com ghada adel aziz al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 5161 (2017) 53 the cartesian product of fuzzy sets is given by : ( , ) = min ( ) , ( ) } …(7) the fuzzy implication operation minconjunctions; t-rate min-conjunctions; accumulation of activated prisoners' rights maxdisjunction; bringing to the definition centroid method, the center of gravity method . the mamdani algorithm has great robustness, clarity inference, but it creates a deformation nonlinear function accessories background α-section of the top, and the operation "center of mass" actually uses the median, that is not the purpose of fuzzy compiler model. well suitable for modulating control, without the abrupt transitions between the values of the output variables. 2.2. the fuzzy inference larsen algorithm the rule base of the rules is based on many inputs and many output variables. in fuzzy inference larsen algorithm, the rules are as follows [15] : if has and has and has , then has and has and has i = 1,2,3,….n …(8) the cartesian product of fuzzy sets is given by : ( x, y ) = ( x ) . ( y) …(9) the fuzzy implicationfuzzy multiplication of species;-t-rate min-conjunction; storage activated opinions max-disjunction. bringing to the definition for choosing a method of method of defuzzification. the findings of function supplies shrink, the base is not changes due to what has sharp transition between managers signals, robustness and adaptability. well suitable for rapid -"hard" regulation. 3. fuzzy control rules and controller models simulation in matlab fuzzy logic a power control v-27 wind turbine, which is a model in matlab simulink program presented, fuzzy control power turbine system algorithm is used and consists of the transformation of the variables of fuzzy logic controller (wind speed and the angle between the position of the nacelle and the wind direction) in its output variables (the angle of attack of the blade, the blade length, angle of the nacelle) with the following interrelated processes: conversion of quantities of clear physical variables derived from measuring wind sensor parameters, the dimensionless linguistic variables; processing of linguistic variables according to the rule base; conversion of the output of the dimensionless variables of fuzzy controller into physical control actions in the matlab software package fuzzy logic. the model consists of the following units: 2 input variables, rule base and 3 output variables as shown in fig.1 regulator functions in terms of the rules of "if then " and thus can enforce a friendly and understanding person representation of knowledge. fig. 1. fuzzy control model with the algorithm mamdani for all output values plots on the matlab gui of a fuzzy logic controller. algorithm used as a fuzzy implication operation uses "minimum", aggregation clipped term set of preconditions produced "maximum" operation. bringing to the definition that is made a method of center of gravity , which is applied to all control loops. as shown in fig. 2 the power control models with different fuzzy inference algorithms. in the first controller has two output variables (the angle of attack and blade length) for the fuzzy inference which applies an algorithm mamdani. in the second regulator output variable is the rotation of the nacelle, for fuzzy inference of this larsen variable algorithm is used. . pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com ghada adel aziz al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 5161 (2017) 54 fig. 2. models regulators for all output values plots on the matlab gui of a fuzzy logic controller with different output algorithms. accurate speed and wind direction is referred to as «inl». at block «input mf» shows the membership function of each terma plurality of input variables. there is a clear statement of the value of the variable in all functions facilities, which are the sum of the final curves. at finally calculated features accessory of each term set. in other words, as far as the entrance is a clear value is "working" "high", "very high", "high mission". further, the non-zero term-sets used in the «rule» blocks as shown in fig 3. fig. 3. block diagram of a non-rigid type regulator. to indicate the requirements or conditions used "if" indicator output or conclusion "then". it is usually prepared from a special knowledge or heuristics and appears as a set of if-then rules. the rules are based on concepts of fuzzy inference and linguistic variables assumptions and implications . fuzzy sets and fuzzy operator is the word of the materials and the fuzzy logic. usually associated with the fuzzy rule is expressed as: if x is n then y is m where x and y are fuzzy variables and the fuzzy values are n and m.[16], in this wind turbine system ,the rule base consists of 16 rules, which has the form: if wind velocity v has n and ψ angle has z, then α has z and lblade has l and dψ has z; according to the rules, inference method above and the fuzzy variable of input and output, the fuzzy control rules are obtained in table 1 as follow: table 1, rules table of fuzzy control. model wind turbine power control system in the application of fuzzy inference algorithm is shown in fig. 4. as described above, this algorithm mamdani and larsen, the inputs of a fuzzy controller type are (from top to bottom as shown in fig.4): wind speed, and the value created by the dynamic wind model , and the angle of misalignment between the position of the nacelle and the wind direction. and the value created by the sum of the angle of the wind direction and the angle of rotation of the nacelle. controller outputs are: blade angle of attack. defines the utilization of wind energy; the length of the blade to change the swept area of the wind wheel. area , and the angle of rotation of the gondola. summing with the wind direction angle, determines angle error. the magnitude of the wind angle, obtained from the dynamic wind patterns, folded to the size of the angle of rotation of the nacelle. from the resulting angle of misalignment between the position and the direction of the nacelle wind calculated projection perpendicular to the plane of the propeller. the value of working in a cube of the wind is supplied to the fourth input. v ψ n h v h c r z α = z lblade = l dψ = z α = m lblade = z dψ = z α = l lblade = z dψ = z α = l lblade = z dψ = pl s α = z lblade = l dψ = z α = s lblade = z dψ = z α = m lblade = z dψ = z α = l lblade = z dψ = pl m α = z lblade = l dψ = ns α = s lblade = z dψ = z α = m lblade = z dψ = z α = l lblade = z dψ = ps l α = l lblade = l dψ = nl α = z lblade = z dψ = z α = s lblade = z dψ = z α = l lblade = z dψ = z pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com ghada adel aziz al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 5161 (2017) 55 4. simulation results design of fuzzy model begins with the definition of the functions supplies for the nonzero terms, linguistically characterize input and output variables . input variables wind speed v and the ψ angle between the wind direction and the position of the nacelle. in this way, you must define the membership function of the variable term-sets v wind speed range from 3 to 25 m / s. membership functions term set wind speed are shown in fig.5. the membership functions of the variable the wind velocity schedule. fig. 5. the membership functions of the variable the wind velocity schedule. wind velocity v n н vh сг 3.5 1 0 0 0 5 1 0 0 0 15 1 0,5 0 0 20 0 0,5 1 0,5 25 0 0 0,5 1 fig. 4. the power control system structure of the wind turbine with a fuzzy inference algorithm. pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com ghada adel aziz al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 5161 (2017) 56 the second input value of the controller model is the angle ψ between the position of the nacelle and the wind direction. fig. 6. show that the numerical values of the membership functions of the variable term-sets "angle ψ » in the range (0; 90). fig. 6. the membership functions of the variable term-sets “angle ψ “. defined membership function sets the variable-term "draft" in the range (0; 45) °. fig.7 the schedule attack membership functions is presented. fig. 7. the membership functions of the variable “angle α “. fig. 8. defined membership function sets the variable-term "blade length l" in the range of (0, 1.3) m. fig. 8. the membership functions of the variable term "blade length l". fig. 9 defined membership function sets the variable term-angle rotating nacelle β tom in the range of (-90, 90) °: angle nacelle deg z s м l 0 1 0 0 0 20 0 1 0 0 45 0 0 0.5 0 60 0 0 0 0.5 90 0 0 0 1 pitch angle deg z s м n l 0 1 0 0 0 0 3 0 0.5 0 0 0 5 0 1 0 0 0 10 0 0 0.5 0 0 15 0 0 1 0 0 20 0 0 0.5 0 0 25 0 0 0 1 0 30 0 0 0 0 0.5 45 0 0 0 0 1 blade length m z s м l 0 1 0 0 0 0.1 0.5 0 0 0 0.2 0 0.5 0 0 0.4 0 1 0 0 0.6 0 0.5 0 0 0.7 0 0 0.5 0 0.9 0 0 1 0 1 0 0 0.5 0 1.1 0 0 0 0 1.2 0 0 0 0.5 1.3 0 0 0 1 pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com ghada adel aziz al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 5161 (2017) 57 fig. 9. the membership functions of the variable term-angle rotating nacelle β. the mode that does not require power limitation of wind turbines, the angle of attack blades must match the optimum operating conditions. fig.10 shows the variation of the pitch angle blade when using fuzzy controller type and pid control. in this mode, it is necessary to maintain the pitch angle blade is equal to zero for the maximum utilization of wind energy. at fuzzy operation controller such as α = 0.3 °, with the functioning of pid controller pitch angle blade changes slight range. fig. 10. the variation of the blade angle of attack (pitch angle) when using fuzzy controller type and pid control. the length of the additional blades of both types of regulators should maintained at the maximum value. it should be noted that the maximum value of the additional part of the blade length dl= 0.5 m on fig. 11. the mode that does not require limiting the power control loop length of the blade generates a command to maintain the maximum length to increase the swept area of the wind wheel. in operation, the controller of the fuzzy type increase in length of the blades is achieved "strong increase" command issued rules base. the graph shows that the length of the extra part of the blade is not equal maximum. this fact is explained by the form of the function accessories-set term "blade length," which has a triangular view. the center of gravity method used to bring to the output values of the blade length, is capable of producing the maximum length for using membership functions of triangular form with vertex point dlmax fig. 11. the length of the additional parts of the blade. in the low speed mode, the target wind control function power is to develop the highest possible power. one of conditions for the maximum use of wind energy is the turn of the nacelle when the direction of the wind. fig. 12. shows graphs changes in the β nacelle angle. β nl ns z ps pl -90 1 0 0 0 0 -80 0,66 0 0 0 0 -70 0,33 0,33 0 0 0 -60 0 0,66 0 0 0 -50 0 1 0 0 0 -40 0 0,66 0 0 0 -30 0 0,33 0 0 0 -20 0 0 0,33 0 0 -10 0 0 0,66 0 0 0 0 0 1 0 0 10 0 0 0,66 0 0 20 0 0 0,33 0 0 30 0 0 0 0,33 0 40 0 0 0 0,66 0 50 0 0 0 1 0 60 0 0 0 0,66 0 70 0 0 0 0,33 0,33 80 0 0 0 0 0,66 90 0 0 0 0 1 pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com ghada adel aziz al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 5161 (2017) 58 fig. 12. graphs changes in the β nacelle angle. rotate the nacelle both types of controllers is made the same way, due to the slow change in the wind direction and the effectiveness of the rotation of the nacelle to the maximum rate of wind energy is estimated as the angle of misalignment w between the position of the nacelle and the prevailing wind direction. at modern wind turbines of high power nacelle rotation is the purpose of maintaining the angle ψ of less than 10 °. at an angle ψ <10 ° rotation of the nacelle for high power wind turbines are not implemented due to continued low wind variations. aspiration reduce the value of the angle to the value ψ = 0 ° continuous rotation of the nacelle it can be dangerous for the mechanical strength of the wind turbine. the values of the angle of misalignment ψ are shown in fig. 13. at this chart shows that up to t = 10 s. ψ angles are increased to values of 10 °, further angle decreases to 2 ° and maintained at that level throughout the regulation time. fig. 13. angle ψ between the position of the nacelle and the prevailing wind direction dψ the capacity charts wind turbines at a slow change in wind speed «working slow» and fast change in the wind direction «fast». fig. 14 shows the power variation graphs of wind turbines, while the closest approximation to the maximum power regulator shows larsen algorithm to change the angle of attack and blade length and algorithm mamdani to rotate the nacelle. fig. 14 the power variation graphs of wind turbines. 5. discussion when developing a model of the power control system based on fuzzy logic, which allows to use different algorithms for control loops. this model allows to experimentally validate the theoretical propositions to improve the efficiency of power control. the power control system of the wind turbine based on fuzzy logic, the change in pitch angle and blade length are rotating nacelle regulator output values on fuzzy logic. the air density was adopted unchanged ρ = 1.009 kg / m3 , and the increase in air temperature from + 15 ° to + 30 ° reduces power by about 5%, and decrease with temperature + 15 ° to 0 ° , it increases the power of the wind flow around 6%. at constant air temperature change of atmospheric pressure from 770 to 730 mm hg. reduces the flow rate of 7%. when a smooth change in the wind direction to pitch angle blade it maintained close to zero due to the high speed drive mechanisms for implementing the rotation of the blade. thus, the use of fuzzy controller type allows you to maintain more accurate necessary pitch angle blade at low wind speeds mode. in an analysis of fig. 12 and fig. 13 get the following conclusion to t = 10 sec. ψ <10 °, so the nacelle rotation is not performed but when ψ > 10 ° rotation of the nacelle run loop and nacelle angles of rotation it can be seen in fig. 12. one can argue about the correctness of the compiled rule base to rotate the nacelle and selected membership functions input and output values so ψ <10 ° over the entire range. the result of good regulation power is achieved using a regulator with larsen algorithm for all circuits. the application shows the remaining two regulators least favorable result, due to a smooth withdrawal process control pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com ghada adel aziz al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 5161 (2017) 59 signals mamdani algorithm, not providing speed. the contour of the low power control algorithm mamdani resource used for circuit with high resource used algorithm larsen, and the results of calculations with fuzzy regulation showed that the power control system of fuzzy logic is most effective when using larsen's algorithm for contour changes the pitch angle and blade length and mamdani algorithm for contour turning the nacelle. in this model, when the controller supports fuzzy type a α = 0.3o , the rule base provides command "to set a value of zero.", and the pitch angle of the blade is constant throughout the control range, the functioning of the speed control loop is represented by the signal change rate limiting unit with the speed of rotation of the blade is limited to 8%, and the rotation of the nacelle up to 5 %. by comparing the results of the functioning of the developed power control system of fuzzy logic and classical control system with pid control, it can be shown that the power control system of fuzzy logic allows to accurately maintain production under the control target function for each work area. and when switching operation of wind turbines from 13.5 m/s to another wind velocity there is no overshoot, typical of classical control systems, and the mode to maintain maximum utilization of wind energy capacity is observed increase by an average of 5%, in the power limit mode achieved a close match the nominal power. 6. conclusions 1. the power control system of the wind turbine parameters values issued by the regulator for certain values of the wind and the angle the ψ angle between the wind direction and the position of the nacelle. 2. it must be taken into account that the increasing and decreasing in air temperature, because it effects on the wind flow power. 3. due to the rapid change in wind direction occur frequently fluctuation of the value of the pitch angle, the using of the pid regulator pitch angle of the blade is changed in a small range. 4. from the simulation program , it can be concluded that the wind turbine capacity of more than 200 kw corner nacelle rotation speed is limited to a value of 0.1 rad / s. and blade rotation is limited to 5-8% . 5. theoretically and by calculation proved the possibility of effective regulation of the power of large wind turbine controller fuzzy type, functioning on the basis of production rules " if – then ". notation pp generated power output cp power coefficient is the ratio of power extracted by the turbine to the total contained in the wind resource is taken equal to 0.4 ρ density of air a swept area of the wind wheel (m) v the velocity of the wind z rapidity, one of the main parameters that characterize the wind turbines for «vestas» is taken equal to 4.2 α pitch angle ( blade angle of attack) ψ angle of misalignment between the position of the nacelle and the prevailing wind direction, d ψ ( change in its value) β nacelle angle lblade the blade length, dl( change in its value) n rotation frequency ω the angular velocity mp the relative moment n working speed, corresponding to the second area of operation of wind turbines h high speed, corresponding to the beginning of the third wind turbine work area vh a very high rate, corresponding to the end of the third working zone wind turbines cr critical speed corresponding to the request shutdown of wind turbines because of the high aerodynamic loads. z zero value m the mean value d great value n normal value nl negative large change ns a small negative change ps positive small change pl positive large change r the minimum blade length r the maximum blade length pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com ghada adel aziz al-khwarizmi 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[10] omar adil m. ali, aous y. ali, balasem salem sumait, “ comparison between the effects of different types of membership functions on fuzzy logic controller performance”, international journal of emerging engineering research and technology volume 3, issue 3, pp 76-83, march 2015 [11] mohammed sabeeh kadhim, mr. ch. ravi kumar,” load frequency control using pid and fuzzy logic control for multi area interconnection system”, international journal of innovative research in electrical, electronics , instrumentation and control engineering vol. 4, issue 7, july 2016 [12] the wind power ,wind engineering market intelligence , http://www.thewindpower.net/turbine_en_20 8_vestas_225.php [13] sumeet kumar gupta, tanuja kashyap,” improvisation of power in variable speed wind turbine dfig modeal with adaptive network based fuzzy logic controller”, international journal of advanced research in electrical,electronics and instrumentation engineering, vol. 5, issue 3, march 2016. [14] j. f. manwell, j. g. mcgowan, and a. l. rogers, wind energy explained: theory, design and application. wiley, 2009. [15] p.n. paraskevopoulos,” modern control engineering”, book, crc press, 367-673pp ,736 pages, 2001. [16] peter buba zirra, timothy umar maigari and wallace ebinum ossai,” a fuzzy based system for determining the severity level of osteomyelitis”, international journal of advanced research in computer science and software engineering, volume 6, issue 6, june 2016. pdf created with pdffactory trial version www.pdffactory.com http://www.gwec.net/ http://www.tandfonline.com/page/models-and http://www.thewindpower.net/turbine_en_20 http://www.pdffactory.com http://www.pdffactory.com )2017( 51-61 صفحة ،2العدد ،13المجلد الھندسیة الخوارزمي جلةم غادة عادل عزیز 61 توربینات الریاح مع منظمات ضبابیة بواسطة خوارزمیة على قدرة سیطرة نموذج محاكاة لنظام ممداني والرسن غاده عادل عزیز الجامعة التكنولوجیة / قسم الھندسة الكھرومیكانیكیة ghadasama@yahoo.com : االلكتروني البرید الخالصة مل ھو بناء منظومة سیطرة القدرة على التوربینات التي تعمل بقوة الریاح بأستخدام المنطق المضبب ، حیث تم فرض ثالث حلقات الھدف من ھذا الع ییم ووالتق تغییر زاویة میالن الریشة، تغییر طول نصل الریشة وتحویل الكنة، لقد تم استخدام قانون العشوائیة إلجراء التعدیالت: للسیطرة على القدرة ت للحظي الدقیق في تغیر ظروف الریاح ، حیث تم استخدام اثنین من الخوارزمیات المختلفة لألستدالل المضبب في حلقة السیطرة ، وقد استخدما لھذا الغرض ، لقد تم التحقق وتطویر ھذه الدراسة بواسطة ھذه الخوارزمیات المختلفة والتي وضعت في صندوق ادوات خوارزمیات ممداني والرسن والطاقات المتجددة والالزمة الكھربائیةالذي كان عملیا قد نفذت باستخدام مفاھیم انظمة السیطرة الذكیة في الھندسة المنطق المضبب و –برنامج الماتالب .للتطبیق في البرنامج ان النظام المضبب للسیطرة على واستنتج، pid تمت المقارنة لفاعلیة عمل النظام المضبب المطور للسیطرة على القدرة مع نظام السیطرة الكالسیكي .القدرة یسمح بالحفاظ على دقة األنتاج تحت ظروف السیطرة المرغوبة لكل مساحة عمل و كیة،أنظمة السیطرة الكالسی ثا الى قیمة سرعة ریاح اخرى تم ایجاد حالة عدم ظھور حالة التخطي و نموذجیة/م13.5عندما یتم تشغیل توربینات الریاح من درجات ، 5من الصفر، اما أذا ازدادت بنسبة " ثا فأن زاویة میالن الریشة ینبغي ان تكون اكبر قلیال/م v> 13.5وجد ایضا انھ عندما تكون سرعة الریاح .فیجب ان یكون طول نصل الریشة الى اقل قیمة ممكنة على أساس استخدام قواعد إنتاج المعرفة لقدرة السیطرة على توربینات الریاح في النوع المضبب إمكانیة التنظیم الفعال استخدام برنامج المحاكاة في لقد أثبت .مثل ھذه التوربینات التي تعمل بقوة الریاح والتي اظھرت السیطرة الفعالة على" ثم إذا " pdf created with pdffactory trial version www.pdffactory.com mailto:ghadasama@yahoo.com http://www.pdffactory.com http://www.pdffactory.com 132140 al-khwarizmi engineering journal al-khwarizmi engineering journal,vol. 12, no. 4, p.p. 132140 (2016) fabrication and characterization of tri metal oxides by chemical spray pyrolysis technique as a gas sensor farhad m. othman* alaa a. abdul-hamead** noor m. ali*** *,**,***department of materials engineering / university of technology *email: fmok4@yahoo.com **email: adr.alaa@yahoo.com ***email: materialengineer38@yahoo.com (received 4 january 2016; accepted 18 may 2016) http://dx.doi.org/10.22153/kej.2016.05.007 abstract in this research tri metal oxides were fabricated by simple chemical spray pyrolysis technique from (sn(no3)2.20 h2o, zn(no3)2.6 h2o, cd(no3)2.4 h2o) salts at concentration 0.1m with mixing weight ratio 50:50 were fabricated on silicon substrate n-type (111). (with & without the presence of grooves by the following diemensions (20µm width, 7.5µm depth) with thickness was about ( 0.1 ±0.05 µm) using water soluble as precursors at a substrate temperature 550 ºc±5, with spray distance (15 cm) and their gas sensing properties toward h2s gas at different concentrations (10,50,100,500 ppmv) in air were investigated at room temperature which related with the petroleum industry. furthermore structural and morphology properties were inspecting. experimental results show that the zn2sno4 and cd2sno4 thin films were achieved from the used salts and samples gas sensitivity which improved with the presence of substrate grooves. which make the sensor suitable for the detection of lower .concentrations of hazard h2s gas in the petroleum industry. keywords: zinc stannate, cadmium stannate, gas sensor, ternary metal oxides, spray pyrolysis, pollutant gases, gas sensitivity, xrd. 1. introduction zero and one dimensional nano-structures of binary semiconducting oxides (2-6 and 4–6 oxides, for example, sno2, zno and tio2 have pulled attention from their interesting properties and potential use in assorted applications, for example, gas sensors, photograph catalysis and sun powered cells. in any case, with active examination in nano technology, there is an earnest requirement for extraordinarily outlined semiconductors to better match the properties of developing materials. this has prompted a restored attention for ternary oxide semiconductors (2–4–6 oxides) of the structure aii 2bivo4, for example, cadmium stannate (cd2sno4), prominently known as tin cadmium oxide (cto), and zinc stannate (zn2sno4), which is called tin zinc oxide (zto). zn2sno4 is recognized for having high electron mobility, high electrical conductivity, and appealing optical properties that makes it reasonable for an extensive variety of utilizations in sunlight based cells, sensors for the recognition of moistness and different burnable gasses, negative electrode material for li-ion battery and as a photo catalyst for the corruption of natural contaminations. contrasted with binary oxides, the tri oxides like zn2sno4 are synthetically more steady making them perfect for applications including compelling conditions [1]. metal oxide semiconductors based sensors are mainstream for distinguishing ignitable gasses at low . concentration levels, attributable to the lower generation costs, high sensitivity and long haul steadiness. the material attributes and size effects of metal oxides have been investigated for its potential in detecting applications. the farhad m.othman al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 132140 (2016) 133 prevalent detecting mechanisms depend on changes in electrical resistance of metal oxide semiconductors because of ion osorption of gases regions on their surfaces. the charge exchange process actuated by .surface responses decides the resistance of the metal oxide. at the point when worked in the encompassing, oxygen gets ion osorbed on the surface of the metal oxide, prompting an adjustment in resistance created by a misfortune or addition of surface electrons as a consequence of adsorbed oxygen responding with the objective gas. in the event that the metal oxide is a n-sort semiconductor, the resistance increments in the. nearness of oxidizing gasses, for example, nitric oxide (no), nitrogen dioxide (no2), ozone (o3) while lessening gasses like carbon monoxide (co), methane (ch4) prompts a decrease in resistance. the opposite is valid for psort metal oxides. the greatness of progress in electrical resistance gives a direct. measure of the convergence of the objective gas present [2]. from the time of julia et al.[3] (1995) the improvement of new materials like tri oxide. semiconductors, for example, cadmium stannate (cd2sno4), galium doped zno, aluminum doped zno and zinc. tin oxide are being investigated effectively. there are a wide range of strategies to combine zto, for example, physical vapor statement (pvd), concoction vapor testimony (cvd), fire pyrolysis, laser-removal, circular segment release, sol-gel strategy, aqueous technique. what's more, solvo-warm techniques [4].ma jin et al.[5] prepared zn-sn-o films deposited on polypropylene adipate (ppa) organic substrate by r.f. magnetron sputtering and characterization of the films is investigated. spray pyrolysis technique can control of sizes and states of crystal structures .structures is essential as it might influence .their electrical and optical characteristics. the physical characteristics of zto rely on upon the technique utilized for production. aqueous development is an appealing and moderately straightforward technique, since crystal growth happens at gentle temperatures and pressure. this strategy is getting to be a standout amongst the most vital devices for developed material handling, especially inferable from its favorable circumstances in the preparing of materials for a wide assortment of innovative applications, for example, hardware, optoelectronics, catalysis production and bio photonics. the variety of morphology and crystallinity of hydrothermally. incorporated zto with the variety of ph of the precursor solution [6]. also, there are other applications for tcos ; liquid crystal displays; anti-static coatings on instrument boards; scraped resistant coatings; corrosion resistant coatings; ohmic contacts to surface-radiating lasers; ohmics contacts to light discharging diodes; ohmic contacts to photodetectors; schottky contacts to photodetectors; and heat mirrors for vitality productive windows and lights [7]. ternary oxides give more prominent adaptability to tune the substance properties of the materials by changing the arrangements thus synthetic sensitivity [8].transition-metal oxides and their compounds have some extraordinary physical properties. in spite of their expansive band holes (>3 ev), which makes them straightforward under ordinary conditions, they can manage a high convergence of carrier electrons with a high mobility [9]. tco films have better bond and lessened film thickness that diminishes the quantity of interconnects and decreases fabricating costs [10]. expanding prerequisites for natural checking, open security, household wellbeing, space makes, air-quality, medicinal analysis, identification of touchy lethal gasses and sensor systems have driven .to developing enthusiasm for superior gas sensor. it is understood that the gas reaction, selectivity and reaction and recuperation time are the three most essential parameters in planning semiconductor metal oxide gas sensor [11]. at last, it must be indicated that one dimensional nanostructures semiconducting oxides have pulled in extraordinary consideration as of late because of their exceptional properties in appreciation of hardware and optics. among them, parallel oxides, for example, zno and sno2 have been centered around for the most part, yet ternary oxides, which may demonstrate better characteristics, are still less considered [12]. the goal of this work is to fabricating different semiconductor-based tri metal oxide gas detector of two mixed film by spray pyrolysis technique , and study some of their structural .properties and sensitivity to some pollutant gases. 2. experimental the work includes the following steps: the first step: • preparation of an aqueous solutions at (50:50)% equal salts ratios with purity 99.9% from 1tin with zinc nitrate (sn(no3)2.20 h2o, zn(no3)2.6 h2o)) 2tin with cadmium nitrate (sn(no3)2.20 h2o, cd(no3)2.4 h2o) farhad m.othman al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 132140 (2016) 134 the concentration was (0.1 m), the acidity was maintained to be ≈6 ph during spraying. the spraying apparatus was manufactured locally in the university laboratories. in this technique, the prepared aqueous solution was atomized by a special sprayer nozzle glass at a heated silicon .substrate fixed at thermostatic controlled hot plate heater. • air was used as a carrier gas to atomize the spray solution with the help of an air compressor with pressure (7 bar), air flow rate (8 cm3/sec) at room temperature. the silicon substrate (0.6 mm thickness) temperature was maintained at 550 ˚c during spraying . grooves were done on silicon substrate via mechanical notch instrument, the dimensions were 7.5 µm depth,20 µm width , number of grooves were 10 separating by 0.1 mm as shown in fig.1 thickness was (0.1 ) µm. • atomization rate was ( 1 nm/s) with (2.5 ml/min) of feeding rate. the distance between the spray nozzle and substrate was kept at (15 ±1 cm) the volume of spray solution was 25 ml, number of spraying (20), time between two spraying (10 sec). • the spray of the aqueous solutions yield the following chemical reactions [13,14]: sn(no3)2.20h2o + 2zn(no3)2.6h2o → zn2sno4↓ + 6no2↑ + o2↑ + 32h2o↑ …(1) sn(no3)2.20h2o + 2cd(no3)2.4h2o → cd2sno4↓ + 6no2↑ + o2↑ + 28h2o↑ …(2) the second step: spraying the solution on the substrate at temperature (550 ±5 ˚c) [16,17,18]. the third step: annealing samples, by using furnace(type nabertherm) at temperature 550˚c for (30 min) and cooling inside furnace. the forth step: inspections which include: 1x-ray diffraction: it was taken by diffractometer type with radiation cukα ( λ= 1.5406 å ). this inspection was carried out in iraqi geological survey board ministry of industrial and mineral, with continuous scanning. 2scanning electron microscopy (sem): the sem study has been carried .out by electron gun tungsten heated filament, resolution 3 nm at 30kv, accelerating voltage 200 v to 30kv, chamber internal size : 160 mm( japan) , with au coating for (20 sec).the setting was done in nanotechnology & advanced materials research center at university of technology. 3atomic force microscopy (afm): it was taken with a digital instruments, typical data has been taken from afm height images include root mean square (rms) and roughness. made in usa, model aa3000 220v. 4optical microscope: it was taken to determine the dimensions of grooves with magnification of 100µm. the inspection was done in nanotechnology & advanced materials research center at university of technology. 5gas-sensing: the gas-sensing experiments were carried out by introducing the thus prepared devices into a home-made test cell, which was consist of a cylinder with cover to restrict prepared gas. the gas was obtained from reaction solution to rising predicted gas. pollutant gas that prepared h2s gas as will be explained in the following reaction equation [14]: fes + 2hcl h2s (g) ↑ + fecl2 … (3) the gases-sensing properties were determined which exposed to various concentrations of the gases (10, 50, 100, 500) ppm. the sensor response was defined using the following equation[15]: sensor response (%) = [(ra−rg)/ra] × 100% … (4) where ra and rg are the electric resistance in air and test gas, respectively. fig. 1. dimensions of grooves. farhad m.othman al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 132140 (2016) 135 3. results and discussion 3.1. x-ray results the result of x-ray diffraction which represent mixing ratio for precipitation films on si substrates are shows in figs.(2, 3). in fig.2 the xrd patterns result of sn0.5:zn0.5 salt mixed shows match with standard value in (jcpds card no. 24-1470) for prepared zn2sno4, with polycrystalline film type with a. cubic system oriented (311) at 100% was grown, no characteristic peaks for any other impurities were observed, suggesting sample have high purity. lattice parameter was calculated a=8.666a⁰. in fig.3 the xrd patterns result of sn0.5:cd0.5 salt mixed shows match with standard value. in (jcpds card no.34-0982) for cd2sno4, with polycrystalline film type also a cubic system oriented (311) at 100% was grown, no characteristic peaks for any other impurities were observed, suggesting sample have high purity. lattice parameter was calculated a=9.088 a⁰. table 1, results data of xrd zn2sno4 / si comp. 2θst(degree) 2θm(degree) ist% im% hkl zn2sno4 17.721 17.720 25 33 111 29.141 29.151 19 28 220 34.291 34.290 100 100 311 35.907 35.900 20 27 222 41.685 41.690 25 30 400 55.116 55.120 30 40 511 silicon 39.89 39.89 100 100 111 table 2, results data of xrd cd2sno4 / si comp. 2θst(degree) 2θm(degree) ist% im% hkl cd2sno4 16.874 16.870 10 26 111 27.681 27.689 40 42 220 32.655 32.66 100 100 311 34.062 34.08 30 41 222 52.102 52.1 70 54 333 57.091 57.1 80 82 440 silicon 39.89 39.9 100 100 111 where 2θst: standard angle (degree) 2θm: measured angle (degree) ist%: standard intensity of peaks (cps) im%: measured intensity of peaks (cps) hkl: miller indices farhad m.othman al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 132140 (2016) 136 fig. 2. xrd spectra of sn 0.5:zn 0.5 / n:si fig. 3. xrd spectra of sn0.5:cd 0.5 / n:si 3.2. sem results figs.4 and 5 show the results of zn2sno4 and cd2sno4 respectively. in fig.4 the surface of zn2sno4 shows monolithic structure contains some grain on top layer at a uniformly distributed that agree with what w.h. zhang and w.d. zhang found [16], the morphology of the grains was. roughly spherical in shape[17]. in fig.5 it can seem that the surface of cd2sno4 containt cavities and craters that due to spraying droplets and process falling on the surface in circles after evaporation leave these craters that agree with v. krishnakumar [18]. fig. 4. sem micrograph image for thezn2sno4 fig. 5. sem micrograph images for thecd2sno4 3.3 afm results afm is powerful technique to investigate the surface morphology at nano to microscale. the surfaces of the films are shown in figs.(6,7) 2 and 3d of the surface, the roughness of zn2sno4 surface was 9.69nm while in the cd2sno4 surface was 13.41nm , this difference depending the nature of material. from afm test also it can seem that zn2sno4 avg. diameter:100.44 nm and in cd2sno4 was avg. diameter:93.74 nm. as a technique spray pyrolysis. regularity were clear on the top surface. however irregularities in the film surface (top view) from the spray technique, which benefited tremendously for the gas sensing properties [19]. farhad m.othman al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 132140 (2016) 137 fig. 6. (2 and 3-d) afm images of thezn2sno4; sn0.5:zn 0.5 salt mixed film. fig. 7. (2 and 3-d) afm images of thecd2sno4; sn0.5:cd 0.5 salt mixed film. 3.4. gas sensitivity the gas detecting attributes are absolutely needy upon the response between semiconducting metal oxides and target gas. instrument of gasdetecting includes the redox response at the metal oxide surface, prompting the adjustment in the consumption layer of the grains .that at last change the electrical resistance of the metal oxide. for the investigation of the gas sensing properties of the oxide films, the optimum operation gas temperature should be fixed initially. figs.(8,9) it can see that increasing the response of sensor by increased gas concentration on the one hand and un increased in response toward h2s gas,which resulted in change oxides consisting as it was see in afm and sem results .in the presence of h2s in air the sample’s resistance decreases due to a red/ox process[20,21]: b h2s(gas) + 3o−a b(ads) → b so2(gas) + b h2o(gas) + 3a e …(5) where : h2s(gas) : is the h2s molecule in the gas phase, o−a b(ads) :an atomic or molecular form of chemisorbed oxygen. e : an electron release ,that is injected into the conduction band of the semiconductor. so2(gas) , h2o(gas) : the molecular reaction products desorbed from the surface. hydrogen sulfide is a bronsted acid, i.e. heterolytic cleavage of the (sh) bond is quite easy, especially in the formation of new donoracceptor bonds. an increase in h2s adsorption on the surface of tri metal oxides can be achieved with the introduction of modifiers that increase the electron-donor ability of surface basic centers (oxygen anions). growth of acidity of the zn2sno4 and cd2sno4 surface has the opposite effect causing difficulties for a heterolytic break of the (h-s) bond in. the h2s molecule and a decrease of the h2s adsorption. it can be observed that sensors of tri metal oxides show response at the same operating temperature in the range from (10 – 500) ppmv, with the maximum response about 60% to 70.61% for zn2sno4 at(10) ppmv without grooves respectively, and for cd2sno4 the maximum response about 83% to 85.61% at(10) ppmv without grooves respectively. for the change in electrical resistance of the metal oxide, there are numerous conceivable responses; the most generally acknowledged response that prompts changes in electrical resistance is the adsorption of gasses on the metal oxide surface. adsorption is only a surface impact and smaller scale stuctured metal oxides have high surface to volume proportion, which upgrades this impact metal oxide gas sensors enhance their affectability and reaction/recuperation time because of nanocrystalline nature of the material related. farhad m.othman al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 132140 (2016) 138 fundamentally the changes are a result of the high surface region. to volume proportion and littler crystallite size contrasted with ordinary microcrystalline materials[22]. fig. 8. gas sensitivity of zn2sno4 for h 2s gas with and without grooves. fig. 9. gas sensitivity of cd2sno4 for h 2s gas with and without grooves. 4. conclusion 1preparing gas sensor with two oxides form of (zn2sno4, cd2sno4) on silicon substrates to detect h2s gas at different concentrations. 2mixing two types of salts used to fabricate two types of tri metal oxide. compounds with different responses toward h2s gas at different concentrations. 3homogenous surface of thin films and crystalline structures; , and cubic for both tri oxides cd2sno4 and zn2sno4 respectively. 4cd2sno4 showed the highest response rate .for all testing gases at the best possible time. 5. references [1] s. baruah, and j. dutta, "zinc stannate nanostructures:hydrothermal synthesis", science and technology of advanced materials, vol.12, no. 1, pp. 18, march 2011. 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[22] l.a. patil, v.v. deo, and m.p. kaushik, "modified cadmium stannate nanostructured thin films prepared by spraying technique for the detection of chemical warfares", intrenational journal of science, spirituality, business and technology (ijssbt), vol. 1, no. 1, pp. 2277-7261, march 2012. �ارز�� ا��� ��� ا����� ��ھ�د � � ����ن� � 4، ا�� د12 ��� ا� ! ،2016( 140-132( 140 ��" ��4زي3-���2 ا��ش ا�����0/� ا� �اري %�,+ '*��( و '�!�& ا%��� #$#�� � �ر � � ��� **أ8ء �$ء ا� 56 *�ھ�د � � ����ن�"*** �&%! /$#"! ا ��اد ��� ھ***،**، �ا ,+*)! ا ('$ * fmok4@yahoo.com:-.ا 203# ا1 ')0و* adr.alaa@yahoo.com -.ا 203# ا1 ')0و: ** materialengineer38@yahoo.com :-.ا 203# ا1 ')0و*** �!$� ا� و<$�i%@0(>)0.1m ( k) .)0ات ا =j#02 وا h.i وا '+د*%�م(fھeا ا 0bc d:3ت ا@+"%# ?5?%! <207=! ا 0ش ا '%�%+;ا :0اري ا �3%7! *6 ا*5ح �ن *6 ا $�ع mno50:50 وز.%! '%n%� ة *6 ا#s+� tns)n ه )+,vw>(111) )!%vx(+د ا>y+>وز وi: د ا��د و<(#م و&&� s7.5µm�0s20µm ،[ض:< �ا c h��>0.05± 0.1(و µm ( +ء�ام ا #]("w>+32e* ^_n> k%"0v 0ارةc !&550و<#ر ºc±5 رش !f+��>15)و cm( (]* i%@ز <)0ا+_n `a+'@ !bn (10,50,100,500 ppmv) !%7b$ ا !s+$j ا c* !73v0� وا !f0_ 0ارة اc !&اء و<#ر�d ا -f. �د اa1(! ا �%$%%c ا"7! �%+"+ت��&%! "g7 اef1%! ا �:0bة < �fر��ر و*n3( ا h%]ev �v g"+� 0 ا1 ')0و.اd,� وا !+d ريe ة ا� .و*,0d ا = �د ا :iوز tns ا �cd2sno4 g7و 0b zn2sno4ة *6 ا1*5ح ا ��)[#*! ھ-اظ0dت ا $)+;i ان اef%! ا1@+"%# ا �:&�> ^$�:v ا _+زات !%"+�cو 3"+$* `a+' 6 ا* k),v -( ز +وا+f 6* !n%n= ا i%@ا )0ا `e' h2s !%7b$ ا !s+$j ا -f 07] ا. محمد عبد الصادق وحيدر وكاظم al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 9, no. 2, p.p. 94102 (2013) )reenia(تأثیر الحجم الحبیبي على مادة متراكبة ذات أساس بولیمري مقواة بدقائق من مادة **حیدر عباس صالل *عبد الحسن محمد عبد الصادق *** كاظم خیون كحلول كوفة -المعھد التقني ***،**،* atlascom2007@yahoo.com :االلكتروني البرید* iron_man_hayder@yahoo.com : البرید االلكتروني** kahlol 2011@yahoo.com :البرید االلكتروني*** (received 9 april 2012; accepted 24 march 2013) ةالخالص ٧٥, ٦٣, ٥٣, ٣٢(المختارة الحجوم الحبیبة تأثیر ودراسة، )الصب الیدوي(متراكبة ذات اساس بولیمري بطریقة ةدماعلى تحضیر حثبیركز ھذا ال رات نج ھ ي أن م ادة االس اس المس تخدمة المتراكب ة المحض رة، حی ث الم ادة على خ واص ) %١٢وبكسر وزني ثابت ( (reenia)من مادة مایكرون ) ٩٠, ).pu(البولي یوریثان ، باإلضافة الى االختبار الفیزیائي )الشّد، االنضغاط، الصدمة والصالدة(لمتراكب المحضر تتضمن عدد االختبارات المیكانیكیة التي أجریت لتقییم النظام ا .، وكل االختبارات اجریت في درجة حرارة الغرفة)النسبة المئویة المتصاصیة الماء( بینما قل ت النس بة المئوی ة لألس تطالة م ع زی ادة لصغیرة ارتفاع عند الحجوم الدقائقیة ا) ومعامل المرونة اقصى مقاومة شد(حیث اظھرت نتائج اختبار الشد وأیضا قیم الصالدة و طاق ة الكس ر ت أثرت ب الحجم ال دقائقي حی ث ارتفع ت .كما ان مقاومة االنضغاط ازدادت مع الحجوم الدقائقیة الصغیرة .الحجم الدقائقي .بینما النسبة المئویة المتصاص الماء ازدادت مع ارتفاع الحجوم الدقائقیة . برمقارنة بالحجوم األكللدقائق الصالدة وطاقة الكسر عند الحجوم الصغیرة والنسبة المئویة لألس تطالة ومعام ل یون ك لمقاومة الشد التي تم الحصول علیھا القصوى وكانت القیم أظھرت النتائج تحسن واضح بالخواص بشكل عام ٠.٤٠٨(، mpa)٥٤.٢( ,)٢ملم/نت ٢٦٨(,%) ١٠( mpa)٣٤.٨(( مرتبة كالتالي صاص الماء كانتومقاومة االنضغاط وطاقة الكسر والنسبة المئویة المت j( ،) shor (d) مایكرون )٩٠(مایكرون ماعدى االمتصاصیة كانت عند الحجم )٣٢( الحجوم عند %)٠.٢٦٦٨( ،)٧٨.٩. .(reenia)دقائق ،مادة متراكبة حیویة ،بولي یورثان: المفتاحیة كلماتال المقدمة .١ ال ذي یش ھده والطب ي نظ رًا للتط ور الص ناعي والتكنول وجي العالم في كاف ة المج االت ، أدت متطلب ات الص ناعة الحدیث ة إل ى ایج اد م واد ھیكلی ة حدیث ة ذات مواص فات ھندس یة عالی ة وك ذلك الحص ول عل ى خ واص ال نس تطیع الحص ول علیھ ا م ن الم واد س یرامیكیة ، البولیمری ة ، ك المواد ال( الھندس یة بش كل منف رد لذلك كان من الض روري أیج اد ب دائل تتك ون م ن .[1]) السبائك عرف ت ب المواد ًادمج مادتین أو أكثر إلنتاج م واد أوس ع اس تخدام وأن مث ل ھ ذه الم واد )composite material(المتراكب ة أصبحت األساس في تغییر وتطویر التصامیم الھندسیة للكثیر من الصناعیة وأكثر مالئمة من الناحی ة االقتص ادیة بحی ث التطبیقات الم واد المتراكب ة أظھ رت .[2] ص ناعةالیمك ن اس تخدامھا ف ي بعض الخواص التي تتناسب مع العدید من التطبیق ات الص ناعیة لذلك فأنھا نالت مكانة مرموقة بین المواد الھندسیة المختلفة، حیث م ادتین أو أكث ر متج اوزة المواد المتراكبة تجم ع ب ین خ واص أن مس اوئ ك ل م ادة إض افة إل ى ذل ك فھ ي تمتل ك إمكانی ة ال تحكم بخواصھا سواء عن طریق نوع ونسب المواد المكونة لھا أو م ن وتع د الم واد المتراكب ة .]١[ خالل تص میمھا وطرائ ق تص نیعھا ذات االساس البولیمري من الم واد الحدیث ة االس تخدام ف ي معظ م لھندس یة والتكنولوجی ة ، وم ن اھ م متطلب ات اس تخدام التطبیقات ا الم واد المتان ة الجی دة واالداء الع الي ومقاومتھ ا لالجھ ادات ھ ذه الداخلیة والخارجیة المؤثرة علیھا اضافة الى مقاومتھ ا للظ روف ف البولیمرات . ]١,٢[ا المحیطة من درجة حرارة وض غط وغیرھ متل ك درج ة عالی ة م ن ھي مواد خامل ة وخفیف ة ال وزن وعموم ًا ت المطیلیة، وھي تمتاز بأنخفاض التوص یلیة الكھربائی ة والحراری ة ل ذلك تس تعمل كع وازل كھربائی ة وحراری ة، وعن د مقارنتھ ا م ع المعادن فإنھا تكون ذات كثافة واطئة واستطالة كبیرة عندما یكون ھنالك تغیر في درجات الحرارة، وتمتلك جساءة واطئ ة ومقاوم ة أم ا الم واد . ]3[لتآك ل وھ ي ألتع د م ن الم واد الص لدة عالی ة ل الس یرامیكیة فھ ي م واد العض ویة وغی ر معدنی ة مث ل االكاس ید والكاربیدات والنتریدات وغیرھا، حیث تمیل الم واد الس یرامیكیة mailto:atlascom2007@yahoo.com mailto:iron_man_hayder@yahoo.com mailto:2011@yahoo.com )2013(94 102 ، الصفحة 2 ، العدد 9 مجلة الخوارزمي الھندسیة، المجلد مد عبد الصادق عبد الحسنمح 95 إل ى أن تك ون ذات توص یلیة كھربائی ة وحراری ة ردیئ ة أي أنھ ا أنخف اض المطیلی ة م واد عازل ة وتتص ف بالھشاش یة الناتج ة ع ن ، أال أنھ ا تمتل ك ص الدة وبالت الي أنخف اض مقاومتھ ا للص دمات وقوة انضغاط وخموال كیمیاویًا، وعلیھ ال یستعمل السیرامیك ف ي ، التطبیقات الواقعة تحت تأثیر األحمال الصدمیة مقارنة بالمعادن . ]3,2[م ع ذل ك فأنھ ا ذات مقاوم ة ل درجات الح رارة العالی ة ف ي ھ ذا المج ال وم نھم ع ض الب احثین ال ذین درس وا وھن اك ب benjamin وزمیل ھ sumaila) malachy ینالب احث iyenagbe ( حیث درس تأثیر مسحوق قشور الف ول ٢٠٠٦عام حی ث كان ت یورث ان السوداني عل ى الخ واص المیكانیكی ة للب ولي حیث تب ین أن مقاوم ة الش د )% ١٠ -٢(من وزنیھكنسبة اإلضافة للمسحوق بینما مقاومة الص دمة ألوزنيع الزیادة بالكسر زادت م .b. v(بینما الباحث .] ٤[نقصت مع الزیادة بمحتوى المسحوق suresh kumar درس ت أثیر م ادة ٢٠٠٩ ع ام )وزمالئ ھ یورث ان عل ى خ واص متراكب ات الب ولي ) alpo4-5(الزیولی ت یورثاني المیكانیكي للبول األداءحیث أظھرت الدراسة تحسن في ھ ذه إض افة من حیث مقاومة الشد ومعامل یون ك وأیض ًا تب ین أن درس الباح ث ٢٠١٠وف ي ع ام .]٥[ المادة تعطي ثبات ح راري )du-xin li تأثیر إضافة األلیاف الزجاجیة القصیرة ) وزمالئھ عل ى الخ واص المیكانیكی ة وخ واص االحتك اك للب ولي یورث ان م ن خ الل الدراس ة أن مقاوم ة الممزوج مع البولي أمای د والح ظ الشد قد زادت عند إضافة ھذه األلیاف لكن مقاوم ھ الص دمة قل ت مع إضافة ھذه األلیاف بینما انخفضت قیم معامل االحتكاك ونسبة تزداد مع إنالقیم لمعامل االحتكاك والبلى یمكن ھذهالبلى كما أن وف ي .]٦[زی ادة الس رعة ونس بة التحمی ل بدراس ة ت أثیر )وزمالئ ھ s. h. kim(ق ام الباح ث ٢٠١٠ع ام الزجاجیة على خواص البولي یورثان حیث الحظ األلیاف إضافة ومقاوم ة الش د ومعام ل یون ك ازدادت م ع قاوم ة االنض غاط مأن إضافة األلیاف الزجاجیة وھذا دلیل على اندماجھا بش كل ص حیح النتائج أن التوصیل الحراري ازداد م ع داخل األرضیة كما بینت زیادة نسبة األلی اف داخ ل األرض یة وأیض ا زادت درج ة ح رارة مع زیادة نسبة األلیاف الزجاجیة داخ ل ) tg( التحول الزجاجیة . ]٧[األرضیة خطة البحث .٢ ت أثیر التقوی ة بالحبیب ات و البح ث ال ى دراس ة ھ ذا یھ دف للبولي یورثان والفیزیائي لمیكانیكيالتدرج الحبیبي على السلوك ا وھي مادة ص یدالنیة كمادة مقویة (reenia)مادة أستخدمتحیث معادلة حموضة المعدة وبما أن البولي یورث ان أم ن طبی ا لستخدم ت والمادة المقوی ة ھ ي طبی ة أص ًال مم ا یعط ي أمكانی ة ف ي اس تخدام الطبي كبدائل في المجال بحثالمادة المتراكبة المحضرة في ھذا ال . أو كمساند للعظام المتضررة التي ال تتعرض ألحمال قویة الجزء العملي .٣ ت م حس اب الكس ر ال وزني لك ل م ن الم ادة االلس اس والم ادة المقوی ة باالعتم اد عل ى قاع دة الخل ط الخاص ة ب المواد المتراكب ة .]٨[وحسب المعادالت اعاله ρc = ∑ vi ρi = v1.ρ1 + v2.ρ2 + … + vn. ρn ...(1) .الكسر الحجمي وھ) v(ھي الكثافة و ) ρ( حیث أن vp = * 100% ...(2) vm = *100% ...(3) ) p (حج م ال دقائق و) c ( حج م الم ادة المتراكب ة و) m ( حج م الكسر الحجم ي ) vm(الكسر الحجمي للدقائق و) vp(االرضیة و .لألرضیة vp = wp …(4) vm = wm …(5) الكس ر ال وزني ) wm(لل دقائق و الكس ر ال وزني ) wp(حیث أن كثافة ) ρc(كثافة االرضیة و) ρm(كثافة الدقائق و)ρp(لألرضیة و .المادة المتراكبة wp = *100% …(6) wm= *100% …(7) ھ و وزن االرض یة )wm(ال دقائق و ھ ي وزن)wp(حی ث أن .وزن المادة المتراكبة ) wc(و wp + wm = 1 …(8) vp+ vm = 1 …(9) المواد المستعملة. ١.٣ أن المواد المستعملة في تصنیع عینات البحث مكونة من مادة المنتج من أنتاج شركة ھنك ل )البولي یوریثان(األساس البولیمریة قویة والتي ھي عبـارة ومادة الت ) الشارقة –االمارات العربیة (في ھو ُمن َتج ص یدلي و(( الصیدالنیة) reenia(عـن دقائق من مـادة یس تعمل لمعادل ة حموض ة المع دِة ال ذي یتك ون م ن خل یط م ن )caco3,mgco3 ( بنس ب)٨٠ ٦٨٠ (mg ،عل ى الت والي وھو على ش كل حب وب باألضافة إلى سكر الفركتوز ومواَد أخرى (( . تھیئة القالب .٢.٣ ت تلخص عملی ة أع داد وتص نیع القال ب لغ رض ص ب العین ات : بالخطوات اآلتیة ×30 × 30)ة قاعـدة زجاجیة باإلبعاد ـــــــــــــــــتھیئ -١ 0.6) cm وذلك الستعمالھا كقاعدة أساسیة للقالب . اد ــــــــــــــــــــــــــــ ـ ة أش رطة زجاجی ة باإلبع ـــتھیئ -٢ (25× 2× 0.5)cm ستعمالھا كجدران للقالبوذلك ال. ی تم تغلی ف القاع دة الزجاجی ة واألش رطة الزجاجی ة -٣ .بنایلون الصق وذلك لمنع التصاق المادة األساس بالقالب یتم تثبیت األش رطة الزجاجی ة بص ورة متقابل ة بوس اطة -٤ .السلیكون الحراري عملی ة التثبی ت بالس لیكون الح راري تك ون م ن ال داخل -٥ .والخارج ومن األركان بعد أكمال عملیة تھیئة القالب تجرى علیھ عملیة تنظیف -٦ .) ١(، كما في الشكل رقم دقیقة ثم تتبعھا عملیة تجفیف )2013(94 102 ، الصفحة 2 ، العدد 9 مجلة الخوارزمي الھندسیة، المجلد مد عبد الصادق عبد الحسنمح 96 .القالب المحضر -١ الشكل تحضیر العینات .٣.٣ أن طرائق تصنیع المواد المتراكبة عدیدة ولكل منھ ا میزاتھ ا المناس ب ومساوئھا وك ذلك لك ل م ن ھ ذه الطرائ ق العدی دة المج ال (hand lay out)الذي تطبق فیھ، لقد ت م أتب اع الطریق ة الیدوی ة ف ي تحض یر العین ات، وت تلخص طریق ة تحض یر وص ب العین ات -:بالخطوات اآلتیة عل ى وف ق حج م یوریثانیتم وزن كمیة من مادة البولي -١ ) . ١:٣ ( القالب المصمم ویتم إضافة المصلد بنسبة ي بواسطة المناخل وب ذلك یك ون یتم تحدید الحجم الحبیب -٢ كما أن الشكل ) ٩٠-, ٧٥-, ٦٣-, ٥٣-, ٣٢-( الحجم كالتالي الناتج لھذه الحبیبات یكون عشوائي نتیجة لعملیة الطحن ألقراص .reeniaمادة وحس ب ) reenia(ی تم وزن كمی ة م ن م ادة التقوی ة -٣ . %)١٢( الكسر الوزني المطلوب التقوی ة وم ادة األس اس عن د تبدأ بعدھا عملیة مزج مادة -٤ درجة حرارة الغرفة ویخلط المزیج بش كل مس تمر وب بطء لتجن ب -٨(ح دوث الفقاع ات خ الل عملی ة الم زج، ویس تمر الم زج م دة وثم نبدأ بأضافة المصلد حیث دقائق إلى أن یتجانس الخلیط ) ١٠ البدء بارتفاع درجة حرارة المزیج والذي یعد دل یًال عل ى نالحظ .ملیة التفاعلبدء ع ی تم ص ب الم زیج الس ائل عل ى ش كل س یل م ن إح دى -٥ لتجن ب ح دوث فقاع ات ھوائی ة ف ي المص بوبة ( جوان ب القال ب بحی ث یس یل إل ى ك ل من اطق ) والت ي تس بب ح دوث الفش ل فیھ ا القال ب بص ورة مس تمرة ومنتظم ة إل ى أن یمتل ئ القال ب یمثل س مك العین ة الذي )ملم ٥(وھو إلى المستوى المطلوب .وھنا یجب أن یكــــــــون القالب بشكل مستٍو تماما یوض ع القال ب عل ى ھ زاز كھرب ائي وتب دأ عملی ة ھ ز -٦ أن (القال ب وذل ك لل تخلص م ن الفقاع ات الموج ودة ف ي العین ة . وكذلك لتغلغل المادة األساس في كل أركان القالب) وجدت س اعة لك ي ) ٢٤(ي القال ب م دة تت رك المص بوبة ف -٧ تتصلب بشكل نھائي حیث یتم الحصول على مص بوبة ث م توض ع ، وھ ذه (55oc)ف ي ف رن تجفی ف م دة س ـاعة وبدرج ة ح ـرارة العملی ة مھم ة إلكم ال البلم رة وللحص ول عل ى أفض ل تش ابك .والزالة االجھادات المتولدة من عملیة التصنیع ش ریطي ذي أس نان یتم تقطیع العینات باستعمال منش ار -٨ ناعمة جدًا وذلك لضمان عدم االھتزاز أثناء قطع العینات وكذلك نعومة أسنان المنشار سوف تعمل على تالفي التش وھات الت ي ق د تحصل أثناء القطع، أما مرحلة ضبط األبعاد فیتم باستعمال جھاز الكوس رة الثابت ة وبع دھا ت تم عملی ة الص قل ب أوراق تنع یم بدرج ة )٤٠٠.( astm)ختبار الشد أخذ طبق ًا للمواص فة االمریكی ة أ -٩ d638m87b) ٢ ( كم ا موض ح بالش كلa-( و)٢b( instron(جھاز نوع والجھاز المستخدم الجراء اختبار الشد ھو موض ح االنكلیزی ة) instron(المص نع م ن قب ل ش ركة ) 1195 . )c -٢(بالشكل b a c d ) bاالمریكیة اصفةوأبعاد عینة الشد حسب الم) aیبین -٢-الشكل العینات بعد عملیة c (d instron 1195)لعینات المصنعةا .الفحص أختب ار االنض غاط أخ ذ طبق ًا للمواص فة االمریكی ة ١٠ (astm d69585) والجھ از )٣(بالش كل كم ا موض ح ) instron 1195(المستخدم الجراء اختبار الشد ھ و جھ از ن وع ٢(بالش كل االنكلیزیة موضح ) instron(المصنع من قبل شركة c-.( b a االمریكیة اصفة والم أبعاد عینة االنضغاط حسب) aیبین -٣-الشكل b ( العینات المصنعة. )2013(94 102 ، الصفحة 2 ، العدد 9 مجلة الخوارزمي الھندسیة، المجلد مد عبد الصادق عبد الحسنمح 97 -iso)وأختبار الصدمة أخذ طبقًا للمواصفة االمریكیة ١١ خدم ھ و جھ از والجھ از المس ت )٤(كم ا موض ح بالش كل (179 .)c -٤(ایزود للصدمة كما موضح بالشكل b a c d أبعاد عینة اختبار الصدمة حسب ) aیبین -٤الشكل جھاز ایزود c)العینات المصنعة ) bة االمریكیة اصفوالم (d العینات بعد عملیة الفحص. ش ور وأختب ار الص الدة ت م بأس تخدام جھ از ص الدة ١٢ (astm d 2240) ةــ وأخ ذ طبق ًا للمواص فة االمریكی وتم اس تخدام جھ از ص الدة ش ور لقی اس )٥(كما موضح بالشكل .)c -٥(ح بالشكل الصالدة كما موض b a c اص فة االمریكی ة وأبعاد عینة الص الدة حس ب الم ) aیبین -٥الشكل b ( العینة المصنعة(c جھاز شور للصالدة. ة الم اء أخ ذ طبق ًا وأختب ار النس بة المئوی ة ألمتصاص ی ١٣ كم ا موض ح . (astm d 57098)للمواص فة االمریكی ة علم ًا ان جمی ع االختب ارات أجری ت ظم ن درج ة ) .٦(بالش كل .حرارة الغرفة b a أبع اد عین ة أختب ار النس بة المئوی ة المتص اص ) aیب ین -٦-الش كل .العینات المصنعة ) bاصفة االمریكیة ومالماء حسب ال النتائج والمناقشة .٤ ) tensile strength( الشد أختبار. ١.٤ للمادة لوحظ ان قیم مقاومة الشد ) ٧(من خالل الشكل مادة تعتمد كثیرًا على الحجم الدقائقي لدقائق المتراكبة المصنعة )reenia( ین قیم مقاومة الشد الداخلة في تكوینھا وبالمقارنة ب زادت فقد لوحظ ان ھذه القیمالنقیة لمادة البولي یوریثانالخاصة وثم) ٣٤.٨ mpa(حیث بلغت ) µm 32( الحجم الدقائقيعند ان تفسیر ذلك ھو .الحجم الدقائقيبزیادة المع بدأت بالنقصان مادة والمتمثلة بدقائق جیدةمقاومة شد ومرونة وجود دقائق ذات )reenia( سوف یسھل من عملیة تغلغلھا في داخل مادة االساس حدوث وھذا یقلل من وخاصة عندما تمتلك احجام دقائقیة صغیرة ان ھذا یزید من قابلیة الوسط كما ، ] ٩ [مادة االساسعیوب داخل على الترطیب وخاصة عندما یكون یوریثان المتمثل بمادة البولي نتھاء من عملیة تصلب المادة الوسط عبارة عن مادة سائلة قبل اال المتراكبة، ان زیادة خاصیة التبلل بین الوسط ومواد التقویة توفر )2013(94 102 ، الصفحة 2 ، العدد 9 مجلة الخوارزمي الھندسیة، المجلد مد عبد الصادق عبد الحسنمح 98 زیادة في مساحة السطح البیني بین مواد التقویة ومادة االساس ، كما وأن المواد المتراكبة ] ٥،٩ [وبین مواد التقویة نفسھا ن تعتمد المدعمة بالدقائق ال تعتمد فقط على خواص مكوناتھا ولك ایضًا على طبیعة السطح البیني بین المكونات وعلى الكسر كما . ]١٠[الحجمي واحیانًا على الشكل الھندسي لھذه الدقائق الزیادة في قیم مقاومة الشد تنخفض مع زیادة تیالحظ ان معدال ى ان زیادة وھذا یعود ال )reenia(مادة الحجم الدقائقي لدقائق الحجم الدقائقي لمواد التقویة الدقائقیة سوف یقلل من مجموع مساحات السطوح البینیة للمادة المتراكبة المتكونة بین مواد التقویة ومادة االساس مما یقلل من قوى الترابط فیما بین ھذه المواد وفي ان تواجد والنھایة یجعل المادة المتراكبة تفشل بحمل اجھادي اقل یصعب عملیةدقائق بأحجام دقائقیة كبیرة داخل مادة االساس لا تغلغلھا الى داخل مادة االساس وخلق العدید من العیوب الداخلیة ] . ١١,٥[وفي النھایة یؤدي الى فشل المتراكب بأحمال شدیة قلیلة 0 5 10 15 20 25 30 35 40 0 32 53 63 75 90 partical size te ns ile s tr en gt h m pa یبین العالقة بین مقاومة الشد والحجم الحبیبي لمادة -٧-الشكل )reenia (سر وزني ثابت عند ك)١٢ %wt.( یالحظ ان قیم معامالت مرونة الشد ) ٨(من خالل الشكل حیث زاد ) reenia(مادة یعتمد كثیرًا على الحجم الدقائقي لدقائق مرونة الشد مع انخفاض الحجم الدقائقي ، فقد كانت اعلى معامل قیم لمعامالت المرونة من حصة العینات المقواة بدقائق ذات حیث كانت قیمة معامل )µm 32(ائقیة صغیرة بحدودحجوم دق .)٢ملم/نت ٢٦٨(المرونة 0 50 100 150 200 250 300 0 32 53 63 75 90 partical size m od ul us o fe la ci tic ity n /m m 2 والحجم الحبیبي معامل المرونةیبین العالقة بین -٨-الشكل ).wt% ١٢(عند كسر وزني ثابت ) reenia(لمادة یب ین العالق َة ب ین النس بة المئوی ة لألس تطالة ) ٩(الش كل رق م ج م الحبیب ي ل دقائق م ادة المحس وبة عن د نقط ة الكس ر والح )reenia(حیث نالح ظ . ، الذي أضیف إلى راتنِج البولي یوریثان أنخف اض نس بة االس تطالة م ع زی ادة الحج م الحبیب ي بالمقارن ة م ع أظھ رت الَنت اِئَج . راتنج البولي یوریثان النقي الخالي من االضافة وھ ي لم ادة %) ١٢(ب أّن أقص ى نس بة مئوی ة لألس تطالة كان ت البولي یوریث ان النقی ة حی ث ت نخفض ھ ذة النس بة م ع أض افة م ادة )reenia ( وم ع الزی ادة ب الحجم الحبیب ي ال ذي یعم ل كمن اطِق تركیِز اإلجھاِد الموقعیة، لذا نسبة اإلطالَة المئویة عند نقطة الكسر الذي یسبب تقلیل حركة المادة , ستنخفض مع زیادة الحجم الحبیبي د م ن العی وب داخ ل الم ادة المتراكب ة االس اس ویخل ق المزی ]٥, ١٠,١١.[ 0 2 4 6 8 10 12 14 0% 32 53 63 75 90 partical size el on ga tio n % at b re ak والحجم النسبة المئویة لالستطالةیبین العالقة بین -٩-الشكل ).wt% ١٢(عند كسر وزني ثابت ) reenia(الحبیبي لمادة ) ( compression testاالنضغاط أختبار. ٢.٤ انضغاط بانھا ذات مقاومة ًاتمتاز الراتنجات المصلدة حراری وذلك بسبب كبسھا للشقوق المتولدة عالیة مقارنة بمقاومتھا للشد، فیھا بینما تؤدي اجھادات الشد الى زیادة الشقوق المتولدة فیھا والتي تنمو بأتجاه عمودي على اتجاه قوة الشد ومن خالل قراءة ) لنكماش الطوا –القوة (جھاز االنضغاط یتم رسم العالقة بین وبذلك یتم ) االنفعال–االجھاد(ھا ترسم العالقة بین والتي من خالل [فشلحساب قیم معامل مرونة االنضغاط واجھاد الضغط عند ال ویعد السلوك االنضغاطي للمواد المتراكبة من . ] ١٢,١٣ الخواص المیكانیكیة المھمة وخاصة عندما تكون مادة االساس تعد مقاومة بولیمریة مما حفز الكثیر من الباحثین لدراستھا أذ االنضغاط الواطئة للمواد المتراكبة من المشاكل االساسیة في ) r. chaplin(، فقد وصف الباحث ]١٣[بعض األحیان buckling(نظریتین للفشل االنضغاطي تمثلت نمط االنبعاج mode ( ونمط القص)shear mode ( الذي ینمو عبر الطبقات الى حصول فشل بشكل الداخلة ضمن المادة المتراكبة مما یؤدي متتابع نتیجة لزیادة التشوة القصي، وان احد اسباب حصول ھذا النوع من الفشل یعود الى وجود بعض العیوب التصنیعیة في المادة التي تشكل مناطق لتركیز االجھادات ألنھ من غیر الممكن ان نصنع مادة خالیة من العیوب بصورة تامة وبذلك یحصل الفشل ان قیم مقاومة نالحظ) ١٠(من الشكل رقم . ]١٢[في العینة مادة مع زیادة الحجم الدقائقي لدقائق ضاالنضغاط القصوى تنخف )reenia( دودححیث بلغت أعلى قیمة ب)٥٤.٢mpa ( عند وان ھذا یعود الى ان وجود دقائق باحجام ، )µm 32(الحجم دقائقیة صغیرة سوف تعمل على عرقلة حركة الشقوق وذلك )2013(94 102 ، الصفحة 2 ، العدد 9 مجلة الخوارزمي الھندسیة، المجلد مد عبد الصادق عبد الحسنمح 99 ولة ملئ الفسح والفجوات الھوائیة الموجودة مابین مكونات لسھ المادة المتراكبة باالضافة الى سھولة انسیاب مادة االساس مما عالوة على انھا تعمل على تؤدي في النھایة الى تقلیل قیم االنفعال ، وعلى العكس ]١٤[ زیادة الترابط بین مكونات المادة المتراكبة حجام كبیرة سوف یساعد على زیادة نشوء فعند استخدام دقائق با الكثیر من العیوب الداخلیة خلقالفجوات والفسح الھوائیة وكذلك مما یقلل من الترابط بین مكونات المادة المتراكبة عند تصلبھا وعلیھ سوف یقلل من قیم مقاومة االنضغاط، ومما یزید من ئقیة كبیرة انخفاض قوة التالصق ھو استخدام دقائق ذات احجام دقا والتي سوف تقف عائقًا امام انسیاب مادة االساس السائلة بین التقویة وبالتالي سوف تقلل من قابلیة التبلل مما یقلل من قوة دقائق . ]١٤,١٥[ االرتباط 0 10 20 30 40 50 60 0% 32 53 63 75 90 partical size co m pr es si on s tre ng th m pa یبین العالقة بین مقاومة االنضغاط والحجم الحبیبي لمادة -١٠-الشكل )reenia ( عند كسر وزني ثابت)١٢ %wt.( impact test ) (اختبار الصدمة . ٣.٤ إن اختبار الصدمة ھو أحد اإلختبارات الدینامیكی ة المیكانیكی ة ، ]١٤[ المھمة التي تتعرض فیھا المادة إلى حمل حركي سریع جدًا وقد تّم إجراء اختبار الصدمة للعین ات بطریق ة ج اربي عن د درج ة طاق ة إن ق یم یالح ظ )١١(رق م م ن خ الل الش كل . حرارة الغرفة ت نخفض م ع زی ادة الحج م الصدم الممتصة أرتفعت ومن ث م ب دأت حی ث بلغ ت اقص ى قیم ة عن د )reenia(م ادة ال دقائقي ل دقائق مقارن ة ) ج ول ٠.٤٠٨(حی ث بلغ ت )µm 32(الحج م ال دقائقي مع مادة البولي یوریثان النقیة حی ث كان ت طاق ة الص دم الممتص ة زى الزی ادة ف ي طاق ة الكس ر للم ادة وتع ) .ج ول ٠.١٥(لھ ا المتراكب ة المحض رة إل ى تحم ل م واد التقوی ة ج زءًا م ن اإلجھ اد الصدمي وذلك لزی ادة الت رابط ب ین الم ادة األس اس وم واد التقوی ة تغلغ ل الم ادة األس اس ب ین لص غر حجمھ ا ال ذي ی ؤدي ال ى نتیج ة عین ة ال دقائق مم ا ی ؤدي ذل ك إل ى زی ادة الطاق ة الالزم ة لكس ر ال كمعوق ات لتق دم الكس ر ) reenia(كما وتعم ل دق ائق م ادة , ]١٥[ وتعتمد ھذه اإلعاقة على مدى قوة الترابط للسطح البیني بین م واد التقوی ة وم ادة األس اس وذل ك النتق ال الكس ر خ الل الس طح البین ي ف ي حال ة ع دم فش ل ال دقائق، ع الوة ) reenia(حول دق ائق م ادة م ادة المقوی ة ة عل ى نس بة الكس رالحجمي لل على اعتماد ھذه العالق وشكلھا وحجمھا ونظام توزیعھا ض من الم ادة األس اس وان زی ادة المناطق البینیة بین المادة األساس ومواد التقویة سوف ی ؤدي إل ى زیادة العیوب ونقص ان ف ي مق دار الطاق ة الالزم ة لح دوث الكس ر الدقائقي ھ و أن سبب االنخفاض الحاصل مع زیادة الحجم . ]١٦[ دقائق الكبی رة داخ ل م ادة األس اس مم ا یقل ل م ن ال لصعوبة تغلغل التقویة وأن ھ ذا س وف یقل ل مس احة لمادةقابلیة تبلل مادة األساس التالمس ومن ثم ضعف قوة الترابط بین مكونات الم ادة المتراكب ة المحض رة ع الوة عل ى خل ق الكثی ر م ن العی وب والت ي تعم ل الجھ ادات ویقل ل م ن الطاق ة الالزم ة للكس ر كمراك ز لتركی ز ا مما یساعد على سرعة الممتصة الصدم طاقةوبالتالي یقلل من قیم .]١٤[نمو الشق وبالتالي الى كسر العینة بحمل صدمي ادنى 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0 32 53 63 75 90 partical size im pa ct e ne rg y j والحجم الحبیبي لمادة طاقة الصدمیبین العالقة بین -١١-الشكل )reenia ( عند كسر وزني ثابت)١٢ %wt.( hardness test ) (اختبار الصالدة .٤.٤ كما ھو معروف ان اغلب اختبارات الصالدة تعتمد على مقاومة المادة لالختراقات عند سطحھا الخارجي وھنالك طرق جراء ، ففي البحث الحالي تم ا]١٥[ لصالدةل مختلفة تمثل دلیًال نوع (shore durometer)فحص الصالدة باستخدام صالدة (shore d) المبین في حیث یتم خالل ھذا الفحص وضع الجھاز من الجھة التي على سطح العینة المراد فحصھا )١٢(الشكل تحتوي أبرة القیاس المرتبطة بنابض یعمل على تحریك مؤشر الجھاز عن طریق الضغط على سطح العینة فیؤخذ أعلى ارتفاع قیم الصالدةان ،للمؤشر عند بدایة الضغط فھو یمثل قراءة الجھاز حیث بلغت تزداد مع انخفاض الحجم الدقائقي )٦(في الشكل ٧٨.٩(حیث بلغت )µm 32(اقصى قیمة عند الحجم الدقائقي shor d( بالمقارنة مع عینات البولي یوریثان النقیة الخالیة من ولكن مع أرتفاع الحجم )shor d ٧٠.٢(أي اضافة حیث بلغت وتفسیر الزیادة في قیم , تدریجیًا نخفاض الدقائقي تبدأ الصالدة بأل الى داخل الدقائق ذات االحجام الصغیرة تغلغل الصالدة ھو سھولة المادة االساس والى داخل الفسح البینیة والى داخل المسامات كل ھذا ةالمتراكب المادة البینیة التي تتكون اثناء عملیة تحضیر ت المادة المتراكبة ساعد في زیادة مساحة التماس ما بین مكونا المحضرة ومن ثم زیادة الترابط فیما بینھا وبشكل متكامل مما اعطى قیم اكثر ایجابیة عند فحص الصالدة وعلى العكس فانھ عند انسیاب مادة البولي ماما ًاوجود دقائق كبیرة سوف تكون عائق بشكل سلس وسھل الى مابین ھذه الدقائق مما ادى الى یوریثان الكثیر من الفجوات والمسامات الھوائیة وبالتالي ادى زیادة خلق .]١٤[الى انخفاض قیم الصالدة )2013(94 102 ، الصفحة 2 ، العدد 9 مجلة الخوارزمي الھندسیة، المجلد مد عبد الصادق عبد الحسنمح 100 62 64 66 68 70 72 74 76 78 80 0% 32 53 63 75 90 partical size sh or d والحجم الحبیبي لمادة الصالدةیبین العالقة بین -١٢-الشكل )reenia ( عند كسر وزني ثابت)١٢ %wt.( water( ماِءالمتصاص النسبة المئویة إل أختبار. ٥.٤ absorption % ( والنسبة الدقائقيالحجم العالقَة بین یبین) ١٣(م رقالشكل ، حیث ُنالحُظ زیادًة في قیمِة اإلمتصاِصألمتصاص الماءالمئویِة البولي یوریثان كما أن إلى أضیفت ) reenia(مادة عندما أن ھوھذا سبَب إّن ,األمتصاصیة تزداد مع زیادة الحجم الدقائقي وتعتبر مادة مسامیة لھا قابلیة المادة المضافة ھي مادة سیرامیكیة المساحة ب حجم الدقائق یعني زیادة زیادةو على أمتصاص السوائل كلما زاد الحجم الدقائقي زادت المساحة أيالمعرضة للماء أنیالحظ من خالل النتائج . ]١٤,١٥[للماءالمعرضة الماصة حیث زادت ) ٠.١٣٧١٦( % الماء للبولي یورثاننسبة أمتصاص .یمة تدریجیًا مع زیادة الحجم الدقائقي ھذة الق 0 0.05 0.1 0.15 0.2 0.25 0.3 0% 32 53 63 75 90 partical size w at er a bs or pt io n % والحجم النسبة المئویة المتصاص الماءیبین العالقة بین -١٣-الشكل ).wt% ١٢(عند كسر وزني ثابت ) reenia(الحبیبي لمادة االستنتاجات .٥ -:مایلي وفي ھذا البحث أظھرت النتائج ائقیة تحسنت مقاومة الشد ومعامل الشد عند الحجوم الدق -١ الصغیرة بینما انخفضت النسبة المئویة لالستطالة مع الزیادة .بالحجم الدقائقي تحسنت مقاومة االنضغاط عند اضافة دقائق ذات احجام -٢ صغیرة وبدأت المقاومة باالنخفاظ مع الزیادة بالحجم الدقائقي . تأثرت طاقة الكسر بالحجم الدقائقي ایضا حیث ازدادت طاقة -٣ .اظ الحجم الدقائقيالكسر مع انخف .الصالدة ازدادت مع نقصان الحجم الدقائقي -٤ ازدادت النسبة المئویة المتصاص الماء مع الزیادة بالحجم -٥ .الدقائقي وكانت القیم كان ھناك تحسن واضح بالخواص بشكل عام -٦ والنسبة المئویة القصوى التي تم الحصول علیھا لمقاومة الشد ومة االنضغاط وطاقة الكسر ومقا الشدلألستطالة ومعامل مرتبة كانت الماء والنسبة المئویةالمتصاص ,)٢ملم/ت٢٦٨(,%)١٠(,mpa)٣٤.٨((اليـكالت )٥٤.٢(mpa،)٠.٤٠٨ j(،) shor (d) ٧٨.٩( ، مایكرون ماعدى ) ٣٢( الحجوم عند %)٠.٢٦٦٨( .مایكرون) ٩٠(االمتصاصیة كانت عند الحجم اعطى افضل الخواص من خالل النتائج تبین ان الحجم الذي -٧ .مایكرون) ٣٢( ھو المصادر .٦ [1] brain s. mitchell, "an introduction to materials engineering and science for chemical and materials engineers", 1st edition, john wiley and sons, inc., 2004. [2] [k. janaki, ," development and characterization of polymer ceramic composites for orthopedic applications" published online 23 december 2008. [3] roger n. rothon, " particulate-filled polymer composites ", by rapra technology limited ,shawbury, shrewsbury, shropshire, sy4 4nr, uk. 2003. [4] malachy sumaila, benjamin iyenagbe," a preliminary mechanical characterization of polyurethane filled withlignocellulosic material",leonardo journal of sciences, .(المكتبة االفتراضیة) . .2006 [5] b. v. suresh kumar & siddaramaiah & m. b. shayan," effect of zeolite particulate filler on the properties ofpolyurethane composite", springer science, 2009. . (المكتبة االفتراضیة). [6] du-xin li a,*, xin denga, jin wangb, jun yangb, xiangxiang li a," mechanical and tribological properties of polyamide 6– polyurethane blockcopolymer reinforced with short glass fibers" science direct, 2010 elsevier. . (المكتبة االفتراضیة). [7] s. h. kim • h. c. park • h. m. jeong," glass fiber reinforced rigid polyurethane", springer science, 2010. (المكتبة االفتراضیة) . [8] jones r. m, "mechanics of composite materials" published by mc. grawhill, new york, 1996. )2013(94 102 ، الصفحة 2 ، العدد 9 مجلة الخوارزمي الھندسیة، المجلد مد عبد الصادق عبد الحسنمح 101 [9] k. k. chawla, "composite materials", springer-verlag , newyork , inc, (1987). [10] jask. r. vinson , tsv-wei chou , "composite materials & their use in structure", publisher by ltd, (1975). [11] john w. weeton , dean m . peters , karyn l . thomas ,"engineering guide to composite materials", published by american society for metals , (1987). [12] [c.r.chaplin, "journal of material science", vol. 12, p.p.(347-352), (1977). [13] "sp system guide to composite engineering materials", (2004), www. sp system. com. [14] rabab asim abdul-aziz," preparation and characterization of polymerceramic composite bio-material", master thesis, materials engineering department, university of technology,2009. [15] [ismail ibrahim marhoon,"mechanical behavior of biomedical composites materials", master thesis, materials engineering department, university of mostanseria,2011 [16] amanda c. lima, luiz augusto h. terrones. ,"impact rupture characteristics of polyethylene composites reinforced with jute fabric" , acta microscopic a vol. 16. 2007, ( المكتب ة . (االفتراضیة mohammed a.sadik a.hassan al-khwarizmi engineering journal, vol. 9, no.2, p.p. 94 -102 (2013) 102 effect the grain size on the polymer matrix composites reinforced by reenia particles mohammed a.sadik a.hassan * hayder abbas sallal** kdhim khaion kahlol *** *,**,***technical institute koufa *email: atlascom2007@yahoo.com **email: iron_man_hayder@yahoo.com ***email: kahlol 2011@yahoo.com abstract synthetic polymers such as polyurethane are used widely in the field of biomedical applications such as implants or part of implant systems. this paper focuses on the preparation of base polymer matrix composite materials by (hand lay-up) method, and studying the effect of selected grain size (32, 53, 63, 75, and 90) µm of (reenia) particles on some properties of the prepared composite. mechanical tests were used to evaluate the prepared system (tensile, compression, impact, and hardness) tests, and a physical test of (water absorption %), and all tests were accomplished at room temperature. where results showed tensile test (maximum tensile strength and modulus of elasticity) high at small grain size while the percentage of elongation decreased with increasing size. as the compressive strength increased with small grain size. and also the values of hardness and fracture energy affected by particle size where the hardness and fracture energy increased at small particles size of compared to larger particles size. while the percentage of water absorption increased at large particle size. in general the results showed clear improvement in properties and maximum values which get it of tensile strength, modulus of elasticity, elongation percentage, compression strength, fracture energy, hardness and water absorption were as follows ((34.8 mpa), (10%), (268 n/mm2), ( 54.2 mpa),( o.408 j), (78.9 shor (d)), (0.2668 %)) at using (32µm)) except water absorption was at (90µm) . mailto:atlascom2007@yahoo.com mailto:iron_man_hayder@yahoo.com mailto:2011@yahoo.com al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 8191 (2014) simulation recording of an ecg, pcg, and ppg for feature extractions noor kamal al-qazzaz* israa f. abdulazez** salma a. ridha*** *,**department of biomedical engineering/ al-khwarizmi college of engineering/ university of baghdad, *department of physics/ college of women science/ university of baghdad email: noorbmemsc81@yahoo.com email: asso193@yahoo.com email: salmaalquzzaz@yahoo.com (received18 april 2014; accepted 27 october 2014) abstract recently, the development of the field of biomedical engineering has led to a renewed interest in detection of several events. in this paper a new approach used to detect specific parameter and relations between three biomedical signals that used in clinical diagnosis. these include the phonocardiography (pcg), electrocardiography (ecg) and photoplethysmography (ppg) or sometimes it called the carotid pulse related to the position of electrode. comparisons between three cases (two normal cases and one abnormal case) are used to indicate the delay that may occurred due to the deficiency of the cardiac muscle or valve in an abnormal case. the results shown that s1 and s2, first and second sound of the heart respectively, can be determined from another signal like ecg. moreover, the position of qrs complex and the end of t wave could be estimated by using ppg signal. keywords: cardiac signal, ecg, pcg, carotid pulse, ppg, signal processing, feature extraction. 1. introduction wave that cannot be readily identified (even visually), especially when murmurs biomedical signals particularly the signals that related with the most important organ such as the heart are received an important view of interest. akay am et al. identified the diastolic segment of the pcg, which is required in some applications in cardiovascular diagnosis such as detection of coronary occlusions using autoregressive modeling of diastolic heart sounds. [1] shaver et al. [2] and reddy et al. [3] included s2 in the part of their article on systolic sounds. however as in the case of s1, s2 is also a nonspecific vibrational are presented. given the temporal relationship between the t wave and s2, it may appear that the former may be used to identify the latter. this, however, may not always be possible in practice, as the t wave is often a low-amplitude and smooth wave and is sometime not recorded at all. st segment elevation or depression may make even visual identification of the end of the t wave difficult. thus the t wave is not a reliable indicator to use for identification of s2 so it may be indicated from the carotid pulse at the beginning of dicrotic notch with some time delay which be illustrated in this paper. 2. electrocardiogram (ecg) the recording of the electrical activity associated with the functioning of the heart is known as electrocardiogram. ecg is a quasiperiodic, rhythmically repeating signal synchronized by the function of the heart, which acts as a generator of bioelectric events [4]. the mailto:noorbmemsc81@yahoo.com noor kamal al-qazzaz al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 8193(2014) 82 heart has four chambers: the upper two chambers called the atria, and the lower two chambers called the ventricles. the atria are thin-walled, low-pressure pumps that receive blood from the venous circulation. located in the top right atrium are a group of cells that act as the primary pacemaker of the heart. through a complex change of ionic concentration across the cell membranes, an extracellular potential field is established which then excites neighboring cells, and a cell-to-cell propagation of electrical events occurs [5]. the first ecg wave of the cardiac cycle is the p wave, which represents activation of the atria. conduction of the cardiac impulse proceeds from the atria through a series of specialized cardiac cells (the a-v node and the his-purkinje system). there is a short, relatively isoelectric segment following the p wave. once the large muscle mass of the ventricles is excited, a rapid and large deflection is seen on the body surface. the excitation of the ventricles causes them to contract and provides the main force for circulating blood to the organs of the body. this large wave appears to have several components. the initial downward deflection is the q wave, the initial upward deflection is the r wave, and the terminal downward deflection is the s wave. the polarity and actual presence of these three components depend on the position of the leads on the body as well as multitude of abnormalities that may exist. in general, the large ventricular waveform is generically called the qrs complex regardless of its makeup. typical amplitude of qrs is 1mv for a normal human heart. following the qrs complex is another short relatively isoelectric segment. after this short segment, the ventricles return to their electrical resting state. and a wave of repolarization is seen as a lowfrequency signal known as the t wave [6]. the normal wave pattern of an electrocardiogram is shown in figure 1. fig.1. four cycles of an electrocardiogram. 3. blood pressure (ppg) it also called as plethysmography signal which is related to the transducer that used in the acquisition process. blood is pumped by the left side of the heart into the aorta, which supplies it to the arterial circuit. due to the load resistance of the arterioles and capillaries, it loses most of its pressure and returns to the heart at a low pressure via highly distensible veins. the right side of the heart pumps it to the pulmonary circuit, which operates at a lower pressure. the heart supplies blood to both circuits as simultaneous intermittent flow pulses of variable rate and volume. the maximum pressure reached during cardiac ejection is called systolic pressure and the minimum pressure occurring at the end of a ventricular relaxation is termed as diastolic pressure. the mean arterial pressure over one cardiac cycle is approximated by adding one-third of the pulse pressure (difference between systolic and diastolic values) to the diastolic pressure. all blood pressure measurements are made with reference to the atmospheric pressure [4]. a typical blood pressure waveform is illustrated in figure 2. fig. 2. blood pressure. blood pressure is the most often measured and the most intensively studied parameter in medical and physiological practice. it is a key source of information for determining hemodynamic state of the patient. by processing arterial blood pressure waveforms, one can track trends such as mean pressure and heart rate. it is also useful in estimating cardiac output, arterial compliance and peripheral resistance. noor kamal al-qazzaz al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 8193(2014) 83 4. phonocardiograph (pcg) the phonocardiograph is an instrument used for recording the sounds connected with the pumping action of the heart. these sounds provide an indication of the heart rate and its rhythmicity. they also give useful information regarding effectiveness of blood pumping and valve action. heart sounds are diagnostically useful. sounds produced by healthy hearts are remarkably identical and abnormal sounds always correlate to specific physical abnormalities. from the beginning till today, the principal instrument used for the clinical detection of heart sounds is the acoustical stethoscope. an improvement over the acoustal stethoscope, which usually has low fidelity, is the electronic stethoscope consisting of a microphone, an amplifier and a head set. electronic stethoscopes can detect heart sounds which are too low in intensity or too high in frequency to be heard in a purely acoustic instrument. the phonocardiographs provide a recording of the waveforms of the heart sounds. these waveforms are diagnostically more important and revealing than the sounds themselves. the sounds are produced by the mechanical events that occur during the heart cycle. these sounds can be from the movement of the heart wall, closure of walls and turbulence and leakage of blood flow. the first sound s1, which corresponds to the r wave of the ecg, is longer in duration, lower in frequency, and greater in intensity than the second sound. the sound is produced principally by closure of the valves between the upper and lower chambers of the heart, i.e. it occurs at the termination of the atrial contraction and at the onset of the ventricular contraction. the closure of the mitral and tricuspid valve contributes largely to the first sound. the frequencies of these sounds are generally in the range of 30 to 100 hz and the duration is between 50 to 100 ms. the second sound s2 is higher in pitch than the first, with frequencies above 100 hz and the duration between 25 to 50 ms. this sound is produced by the slight back flow of blood into the heart before the valves close and then by the closure of the valves in the arteries leading out of the ventricles. this means that it occurs at the closure of aortic and the pulmonic valves. the heart also produces third s3 and fourth s4 sounds but they are much lower in intensity and are normally inaudible. the third sound is produced by the inflow of blood to the ventricles and the fourth sound is produced by the contraction of the atria. these sounds are called diastolic sounds and are generally inaudible in the normal adult but are commonly heard among children [7]. fig. 3. heart sound. 5. physical relation between ecg, pcg and ppg each heartbeat begins with a signal generated by the sinoauricular (sa) node, commonly called the pacemaker. as the signal spreads through atrial muscle the atria respond by contracting (atrial systole). at this time the ventricles are relaxing (ventricular diastole) and the atrioventricular valves are open, the semilunars are closed. the ventricles are filling with blood, preparing for ejection. the atrioventricular (av) node picks up the pacemaker signal and, after a short delay that allows the atria to complete systole and enters diastole, sends the signal down the atrioventricular conduction system to the ventricles stimulating them to contract (ventricular systole). when the ventricles contract, ventricular pressure increases above atrial pressure and the atrioventricular valves close (1st heart sound). ventricular pressure continues to increase, and when it exceeds arterial pressure, the semilunars open and blood is rapidly ejected into the pulmonary trunk and aorta. the ventricles complete systole and enter diastole. as the ventricles relax ventricular pressure falls below arterial pressure and the semilunar valves close (2nd heart sound). when ventricular pressure falls below atrial pressure, the atrioventrcular valves open and ventricular filling begins again. at this time (a period called diastasis) the atria and die ventricles are relaxed and awaiting the pacemaker to signal the next cardiac cycle. noor kamal al-qazzaz al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 8193(2014) 84 the electrical events of the cardiac cycle can be recorded in the form of an electrocardiogram (ecg). [8]. 6. methodology these signals are usually recorded by using surface electrodes. all the signals were recorded simultaneously with sampling rate of 1000 hz. the dataset is available at (ftp://ftp.ieee.org/uploads/press/rangayyan/). the surface electrodes may be disposable, adhesive types or the ones, which can be used repeatedly. a ground electrode is necessary for providing a common reference for measurement. these electrodes pick up the potentials produced by the contracting muscle fibers. the signal can then be amplified and displayed on the screen of a cathode ray tube (the oscilloscope displays ecg, pcg and ppg waveforms) [4]. fig. 4. correlation of the heart sound with the electrical and mechanical events of the heart. a schematic block diagram of the proposed system is illustrating the concept of this paper is shown in figure 5. fig. 5. block diagram of the proposed system. a. signal acquisition the ecg, carotid pulse, and pcg signals were recording from three channels with sampling frequency of 1000 hz. the signals that used in this paper were recorded from three volunteer (adult male, male subject of 23 years) are normal and (female, 14 months) has systolic murmur, and patient suspected to have pulmonary stenosis, ventricular septa1 defect, and pulmonary hypertension [9]. the data of each person are collected using three channels data acquisition system as shown in figure 6a, 6b and 6c) below. b. dc off set removing the small dc offset in the signal as shown in the figure below is caused due to the instrumentation amplifier in that used in the medical equipment that used to collected the signal of interest. to remove these dc offsets, simply subtract them from the recorded raw signals as shown in figure (7a, 7b and 7c). now the dc offset was removed. noor kamal al-qazzaz al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 8193(2014) 85 fig. 6a. pcg, ecg and ppg pulses from normal adult male. fig. 6b. pcg, ecg and ppg pulses from normal male subject 23 years. 0 0.5 1 1.5 2 2.5 x 10 4 -5 0 5 p c g pcg, ecg, and carotid pulse signals from normal adult male 0 0.5 1 1.5 2 2.5 x 10 4 -5 0 5 e c g 0 0.5 1 1.5 2 2.5 x 10 4 -5 0 5 c a r o t id time in seconds 0 0.5 1 1.5 2 2.5 x 10 4 -5 0 5 p c g pcg, ecg, and carotid pulse signals from ( normal male subject, 23 years) 0 0.5 1 1.5 2 2.5 x 10 4 -5 0 5 e c g 0 0.5 1 1.5 2 2.5 x 10 4 -5 0 5 c a r o t id time in seconds noor kamal al-qazzaz al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 8193(2014) 86 fig. 6c. pcg, ecg and ppg pulses from abnormal female. fig. 7a. pcg, ecg and ppg pulses from normal adult male without dc drift. 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 x 10 4 -5 0 5 p c g pcg, ecg, and carotid pulse signals has systolic murmur(female, 14 months) 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 x 10 4 -5 0 5 e c g 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 x 10 4 -5 0 5 c a r o t id time in seconds 1 1.5 2 2.5 3 3.5 4 4.5 5 -1 0 1 pcg dc drift=-0.0681 second v o lt s pcg signal after cancellation dc drift and normalization 1 1.5 2 2.5 3 3.5 4 4.5 5 -1 0 1 ecg dc drift=-0.8566 second v o lt s ecg signal after cancellation dc drift and normalization 1 1.5 2 2.5 3 3.5 4 4.5 5 -1 0 1 ppg dc drift=-1.8135 second v o lt s ppg signal after cancellation dc drift and normalization noor kamal al-qazzaz al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 8193(2014) 87 fig. 7b. pcg, ecg and ppg pulses from normal male subject 23 years without dc drift. fig. 7c. pcg, ecg and ppg pulses from abnormal female without dc drift. 1 1.5 2 2.5 3 3.5 4 4.5 5 -1 0 1 pcg dc drift=-0.0681 second v o lt s pcg signal after cancellation dc drift and normalization 1 1.5 2 2.5 3 3.5 4 4.5 5 -1 0 1 ecg dc drift=-0.8566 second v o lt s ecg signal after cancellation dc drift and normalization 1 1.5 2 2.5 3 3.5 4 4.5 5 -1 0 1 ppg dc drift=-1.8135 second v o lt s ppg signal after cancellation dc drift and normalization 1 1.5 2 2.5 3 3.5 4 4.5 5 -1 0 1 pcg dc drift=-0.0846 second v o lt s pcg signal after cancellation dc drift and normalization 1 1.5 2 2.5 3 3.5 4 4.5 5 -1 0 1 ecg dc drift=-0.0639 second v o lt s ecg signal after cancellation dc drift and normalization 1 1.5 2 2.5 3 3.5 4 4.5 5 -1 0 1 ppg dc drift=-0.2616. second v o lt s ppg signal after cancellation dc drift and normalization noor kamal al-qazzaz al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 8193(2014) 88 7. feature extraction several statistical features can be extracted from the three causes; by calculating the maximum, minimum, mean, standard deviation, variance, and signal to noise ratio for all the three cases using matlab programs where (max: largest elements, min: smallest elements, mean: the average value of a signal. it is found by adding all of the samples together, and divide by n as shown in the following equation:     1 0 1 n i ix n mean in words, sum the values in the signal, x, by letting the index, i, run from 0 to n-1. then finish the calculation by dividing the sum by n. std: standard deviation the standard deviation s of a data vector x: 2/1 1 2 1                  n i i x n std x where and n is the number of elements in the sample. the two forms of the equation differ only in n-1 versus n in the divisor [10]. snr is an engineering term for the power ratio between a signal (meaningful information) and the background noise. the biomedical signals normally have a wide dynamic range. snrs are usually expressed in terms of the logarithmic decibel scale. in decibels, the snr is 20 times the base-10 logarithm of the amplitude ratio, or 10 times the logarithm of the power ratio: snr=10 log (es/en), where es is the average signal amplitude and en is average noise amplitude measured within the system bandwidth [11]. signal-to-noise ratio (snr), which is equal to the mean divided by the standard deviation. another term is also used, the coefficient of variation (cv). this is defined as the standard deviation divided by the mean, multiplied by 100 percent. better data means a higher value for the snr and a lower value for the cv [10]. 8. delay detection a cardiac cycle may be divided into two important parts based upon ventricular activity: systole and diastole. the systolic part starts with s1 and ends at the beginning of s2; s1 in pcg may be begun at the same instant as the qrs complex is end, the dicrotic notch in the carotid pulse may be used to locate the beginning of s2 in pcg which is at the end of the t wave of the ecg signal. thus, if there are both ecg and carotid pulse signals along with the pcg, it becomes possible to break the pcg into its systolic and diastolic parts [9]. the demarcation was performed by visual inspection to detect the time delays between these intervals in the three channels pcg, ecg and ppg signals and then compare between the normal and abnormal subjects with (systolic murmur due to aortic stenosis). 9. results and discussion a. feature extraction the following table illustrated the feature that can be extracted from the three cases. the results are shown in table 1, to compare between the standard deviation of the (normal cases1 and 2 and the abnormal case 3) the result shown that maximum amplitude (higher than normal) in case 3, the mean or the drift which cased due to the instrumentation amplifier is already removed during processing to reduce the base line drift noise, the fluctuation from the main axes were evidenced from the standard deviations and their variance. the signal to noise ratio in linear scale they are within the medical instrument range due to using filters inside the instrument that used to collect the data from it.     n i ix n x 1 1 noor kamal al-qazzaz al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 8193(2014) 89 table 1, the feature that can be extracted from the three cases. max min mean std variance snr(db) case 1 pcg 2.9405 -2.6906 -0.068 0.4114 0.1692 7.812 ecg 2.6660 -2.6625 -0.8566 0.6905 0.4768 0.9359 ppg 2.7872 -2.0198 -1.8135 1.1985 1.4300 1.8084 case 2 pcg 2.7206 -2.6364 -0.0834 0.2955 0.0873 -5.4944 ecg 2.6671 -0.9299 0.1217 0.3201 0.1024 -4.198 ppg 3.4103 -2.2781 -0.1774 1.3245 1.7543 -8.7321 case 3 pcg 4.2967 -3.6714 -0.0846 0.8507 0.7237 -10.021 ecg 3.8950 -4.0739 -0.0639 0.6569 0.4315 -10.123 ppg 3.9780 -3.0890 -0.8566 1.333 1.7776 -7.0731 b. delay detection the following figures show clearly a different time delays in the three cases at the three channels which is recorded instantaneously. case 1: normal adult male fig. 8. time delay between intervals case 1. 1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2 -1 -0.5 0 0.5 1 1.5 x: 1.283 y: 0.428 second m v o lt ecg end qrs complex s1 s2 end of t wave d notch x: 1.305 y: -0.007805 x: 1.55 y: 0.003371 x: 1.711 y: 0.4694 x: 1.611 y: 0.4729 pcg ecg ppg noor kamal al-qazzaz al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 8193(2014) 90 case 2: normal male subject 23 years fig. 9. time delay between intervals case 2. case 3: abnormal subjects with (systolic murmur due to aortic stenosis) fig. 10. time delay between intervals case 3. 1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2 -1 -0.5 0 0.5 1 1.5 x: 1.314 y: 0.005293 second ecg m v o lt end qrs complex s1 end of t wave s2 d notch x: 1.325 y: 0.8094 x: 1.598 y: 0.5013 x: 1.673 y: 0.4725 x: 1.603 y: 0.002476 pcg ecg ppg 1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2 -1 -0.5 0 0.5 1 1.5 x: 1.207 y: -0.01608 second ecg m v o lt s1 s2 end of t wave end qrs complex d notch x: 1.469 y: 0.05983 x: 1.683 y: -0.08411 x: 1.429 y: 0.63x: 1.19 y: 0.5029 pcg ecg ppg noor kamal al-qazzaz al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 8193(2014) 91 from the above recorded, signals can be used to diagnose many cardiac diseases due to the readily identifiable waveforms in the pcg, ecg, and ppg for the three cases. the pcg is a more complex signal, which cannot be visually analyzed except for the identification of features such as s1 and s2 and their components. the visual identification of s1 and s2 is possible if there are no murmurs between the sounds, and if the heart at high rates and with the presence of murmurs or premature beats, identification of s1 and s2 could be difficult. because the ecg and pcg are concurrent phenomena, it is noticeable difference that the former is electrical while the latter is mechanical (sound or vibration). the qrs wave in the ecg is directly related to ventricular contraction, as the summation of the action potentials of ventricular muscle cells. as the ventricles contract, causing the initial vibrations of s1. it begins immediately after the qrs complex as shown in figure 8 and 9 with small delays only comparing with the third case (patient with systolic murmur and have pulmonary stenosis, ventricular septa1 defect, and pulmonary hypertension). the phonocardiogram and the carotid pulse can be identified from the diastolic segment of the pcg ventricular systole ends with the closure of the aortic and pulmonary valves, the components of the second heart sound s2 (end of contraction) is also indicated by the t wave in the ecg, and s2 appears slightly after the end of the t wave. s2 may be taken to be the end of systole and the beginning of ventricular relaxation or diastole. they cannot be readily identified (even visually), especially when murmurs are present (case 3). the relationship between the t wave, s2, and the d notch appeared in figure 8 and 9. the t wave is simultaneously appearing with the s2, and the d notch with a small delay with respect to each other but in the normal cases the d notch used as an indicator of the end of systole or beginning of diastole event. its evidently from case 3 the patient with systolic murmur, pulmonary stenosis, ventricular septa1 defect, and pulmonary hypertension (abnormal case) the s2, d notch and the t wave are not appeared in the same time due to the defect in the valves and cardiac muscles. this study has some limitations which need to be paid attention. first of all, it can be noted that, only 3 biological signals were predominantly simulated due to the fact that these studies need a high sensitive medical devices in addition to ethical approval in order to examine the patients. moreover, the sample size has often been small and need for additional studies to obtain promising results. despite these drawbacks, this study may provide a means to statistically identify the relation between ecg, pcg and ppg. lastly, the heart is widely assessed by cardiologist doctors using visual inspections but recently a new specific medical devices are used to evaluate and predict different cardiac diseases. finally, this study defined statistical indicators that might help medical doctors and clinicians in planning and providing a more reliable prediction of the course of the disease in addition to the optimal therapeutic program to provide cardiac patients additional years of a higher quality of life. 10. conclusion from the results, it can be concluded that the first heart sound (s1) and the second heart sound (s2) can be determined from other feature such as using the ecg and estimate the position of the qrs complex or the end of the t wave or from using the ppg to indicate the end of the t wave which is related to the end of the ventricular systole. in case of pathology such as murmurs the pcg and its components are not indicated in same as normal persons due to the defect in the valves and may be in the muscle itself. in this study, several statistical features can be suggested for indicating the delay that may occurr due to the deficiency of the cardiac muscle or valve in an abnormal case which might be useful and would be helped in the clinical evaluation. 11. references [1] akay am, semmlow jl, welkowitz w, bauer md, and kostis jb. “detection of coronary occlusions using autoregressive modeling of diastolic heart sounds”, ieee transactions on biomedical engineering, 37(4):366-373, 1990. [2] shaver ja, salerni r, and reddy ps., “normal and abnormal heart sounds in cardiac diagnosis, part i: systolic sounds. current problems in cardiology”, 10(3): 168, 1985. [3] reddy ps, salerni r, and shaver ja., “normal and abnormal heart sounds in cardiac diagnosis, part 11: diastolic sounds. current problems in cardiology”, l0(4):l-55, 1985. noor kamal al-qazzaz al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 8193(2014) 92 [4] khandpur r.s “handbook of biomedical instrumentation”, second edition (2003), tata mcgraw-hill publishing company limited, new delhi, pg: 35-37, 208-209, and 204-205. [5] geselowitz d.b “in the theory of the electrocardiogram”, proc ieee 77:857, 1989. [6] bronzino j.d “the biomedical engineering handbook”, a crc handbook published in cooperation with ieee press, pg 184-185, 2000. [7] joseph j. carr and john m. brown, “introduction to biomedical equipment technology”, 4/e, new delhi: pearson education india, 2001. [8] www.biopac.com [9] rangarai m. rangayyan., "biomedical signal analysis a case-stady approach", john wiley and sons, inc., 2002. [10] steven w. smith, "the scientist and engineer's guide to digital signal processing",2006 [11] ch. renumadhavi, s.madhava kumar, a. g. ananth, nirupama srinvasan, “a new approach for evaluation snr of ecg signals and its implementation”, 2006. http://www.biopac.com/ (2014)8193 ، صفحت4، انعذد10دجهت انخوارزيي انهنذسيت انًجمو انقسازنور كًال 93 تسجيم يحاكاة يخطط انقهب انكهربائي، يخطط اصواث انقهب، يخطط انتحجى ألستخراج انخصائص ***عهي رضاسهًى **اسراء فائق عبذ انعسيس *انقسازنور كًال جايعت بغذاد /كهُت انهُذست انخىارسيٍ /قسى هُذست انطب انحُاتٍ**،* جايعت بغذاد /كهُت انعهىو نهبُاث /قسى انفُشَاء*** noorbmemsc81@yahoo.com: انبزَذ االنكتزوٍَ* asso193@yahoo.com: انبزَذ االنكتزوٍَ** salmaalquzzaz@yahoo.com: انبزَذ االنكتزوٍَ*** انخالصت فٍ هذا انبحج استخذو َهج جذَذ . انتطىر فٍ يجال هُذست انطب انحُاتٍ انذٌ حصم يؤخزا، ادي انً تجذَذ االهتًاو بانكشف عٍ انعذَذ يٍ االحذاث يخطظ اصىاث انقهب، يخطظ انقهب انكهزبائٍ و : خُص و هٍنهكشف عٍ يعطُاث و عالقاث يحذدة بٍُ حالث يٍ االشاراث انحُىَت انتٍ تستخذو فٍ انتش نتاٌٌ يُهًا حاااحٍ) انًقارَت بٍُ هذِ انحاالث انخالث . يخطظ انتحجى و انذٌ َسًً فٍ بعض االحُاٌ انُبضت انتاجُت انًتعهقت بًىقع انقطب انكهزبائٍ ربًا تستخذو فٍ انكشف عٍ انتأخُز انذٌ قذ َحذث َتُجت نهقصىر فٍ انعضهت انقهبُت او صًاو قهبٍ فٍ انحاالث غُز ( حانت غُز طبُعُت انخانختو تاٌطبُعٍ يٍ فأٌ جشءكذنك . ، يٍ انًًكٍ حسابهًا يٍ اشارة اخزي يخم اشارة انقهب انكهزبائٍ(انصىث االول و انخاٍَ)انُتائج اظهزث اٌ اصىاث انقهب . انطبُعُت .االشارة انقهبُت و َهاَتها يٍ انًًكٍ انتُبؤ بها عٍ طزَق اشارة انتحجى mailto:noorbmemsc81@yahoo.com 3643 al-khwarizmi engineering journal, vol. 1 corrosion effective of containing selective organic component majid h. abdulmajeed* * department of materials engineering / university of technology ** energy and renewable energies technology center *** energy and renewable energies technology center (received abstract this work involves studying the effect of adding of pure al and its alloys in condensed synthetic automotive solution (csas) at room temperature. this mixture indicates the increasing of octane number in previous study and in this study show the increasing in corrosion resistance through the decreasing in corrosion rate values. electrochemical measurements were carried out by potentiostat at 3 mv/sec to estimate the corrosion parameters using tafel extrapolation method, in addition to cyclic polarization test to know the tested medium. the cathodic tafel slope (bc) were slopes (ba) were varied after addition of the mixture. the surface of the tested material, which is less permeable and can even obstruct the metal dissolution reaction but still permits an electrochemical reaction to occur. this behavior can be achieved by the electronic density on oxygen and nitrogen atoms in the organic component keyword: corrosion of alalloys, potentiostatic measurements, corrosion in fuel 1. introduction aluminium and most aluminium alloys have good corrosion resistance in natural atmospheres, fresh water, seawater, many soils, many chemicals and their solutions, and most foods. t resistance to corrosion is the result of the presence of a very thin, compact, and adherent film of aluminium oxide on the metal surface whenever a fresh surface is created by cutting or abrasion and is exposed to either air or water, a new film forms rapidly, growing to a stable thickness. the film formed in air at ambient temperature is ≈ 5nm (50 ao) thick. the thickness increases with increasing temperature and in the presence of water. the oxide film is soluble in alkaline solutions and in strong acids, with some 1 khwarizmi engineering journal, vol. 11, no. 4, p.p. 3643 (201 corrosion effective of condensed synthetic automotive solution containing selective organic component mixtures majid h. abdulmajeed* slafa i. ibrahim** eiman ali e. sheet** * department of materials engineering / university of technology ** energy and renewable energies technology center/ university of technology *** energy and renewable energies technology center/ university of technology *email: majed_hamed60@yahoo.com chemistsulsfa_59@yahoo.commail:**e eman_sheet@yahoo.co.uk mail:***e (received 22 february 2013; accepted 18 june 2014) this work involves studying the effect of adding some selective organic component mixture on corrosion behavior of pure al and its alloys in condensed synthetic automotive solution (csas) at room temperature. this mixture ncreasing of octane number in previous study and in this study show the increasing in corrosion resistance through the decreasing in corrosion rate values. electrochemical measurements were carried out by potentiostat at 3 mv/sec to estimate the corrosion parameters tafel extrapolation method, in addition to cyclic polarization test to know the pitting susceptibility of materials in ) were increased after adding the organic component mixture. but the anodic tafel ) were varied after addition of the mixture. the increase in cathodic slope indicates the presence of a film on material, which is less permeable and can even obstruct the metal dissolution reaction but still permits an electrochemical reaction to occur. this behavior can be achieved by the electronic density on oxygen and the organic component mixture. alloys, potentiostatic measurements, corrosion in fuel. aluminium and most aluminium alloys have good corrosion resistance in natural atmospheres, fresh water, seawater, many soils, many chemicals and their solutions, and most foods. this resistance to corrosion is the result of the presence of a very thin, compact, and adherent film of aluminium oxide on the metal surface [1]. whenever a fresh surface is created by cutting or abrasion and is exposed to either air or water, a forms rapidly, growing to a stable thickness. the film formed in air at ambient ) thick. the thickness increases with increasing temperature and in the presence of water. the oxide film is soluble in ong acids, with some exceptions, but is stable over a ph range of ( to 9.0). aluminium alloys are used in storing, processing, handling, and packaging of a variety of chemical products. they most dry inorganic salts. range, the resist corrosion in solutions of most inorganic chemicals but are subject to pitting in aerated solutions, particularly of halides [1]. there are many studies concerned with gasoline such as the effect of ethanol blends on corrosion rate in the presence of different materials of construction used for transportation, storage and fuel tanks [2] and fuel pumps [3]. hamilta and co corrosion performance of al synthetic condensed automotive s other works [5,6] in alcoholic fuels. al-khwarizmi engineering journal (2015) condensed synthetic automotive solution on al-alloys eiman ali e. sheet*** * department of materials engineering / university of technology university of technology university of technology mixture on corrosion behavior of pure al and its alloys in condensed synthetic automotive solution (csas) at room temperature. this mixture ncreasing of octane number in previous study and in this study show the increasing in corrosion resistance electrochemical measurements were carried out by potentiostat at 3 mv/sec to estimate the corrosion parameters pitting susceptibility of materials in mixture. but the anodic tafel cathodic slope indicates the presence of a film on material, which is less permeable and can even obstruct the metal dissolution reaction but still permits an electrochemical reaction to occur. this behavior can be achieved by the electronic density on oxygen and exceptions, but is stable over a ph range of (≈ 4.0 aluminium alloys are used in storing, processing, handling, and packaging of a variety they are compatible with within the passive ph range, the resist corrosion in solutions of most chemicals but are subject to pitting in aerated solutions, particularly of halides [1]. there are many studies concerned with gasoline such as the effect of ethanol-gasoline corrosion rate in the presence of different materials of construction used for transportation, storage and fuel tanks [2] and fuel pumps [3]. hamilta and co-workers [4] studied corrosion performance of al-si-cu alloys in a synthetic condensed automotive solution, while other works [5,6] in alcoholic fuels. nie et al. [7] majid h. abdulmajeed al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 3643(2015) 37 studied corrosion behavior of metallic materials in ethanol-gasoline alternative fuels. eiman and jehad [8] studied the relative performance of compression ignition engine using various blends of diesel – ethanol fuels. alessandra regina pepe ambrozin et al.[9] studied metallic corrosion related to mineral fuels and biofuels utilization. the utilization of these fuels implies their closer contact to metallic materials, which comprise vehicle, storage, and transportation systems. thus, metallic corrosion could be related to fuels and biofuels utilization. they observed that the ethanol is the most corrosive and gasoline the least. 2. experimental procedure pure aluminium and its alloys were cut into square shape with (1cm*1cm) area, and made into electrode by pressing a copper wire into a hole on one side and then insulating all but one side with an epoxy resin. the open side was polished mechanically to a mirror finish, rinsed in distilled water and stored in desiccators. the alloys were used al-cu-mg, al-mg, and al-si-cu .the composition were measured by using niton xrf(portable x-ray fluorescence spectroscopy) device –model xlt (uk),in laboratories of materials engineering department -university of technology .table (1) shows the chemical composition of al-alloys. the electrochemical glass was of the usual type with provision for working electrode (pure metal and its alloys), auxiliary electrode (pt electrode), and a luggin capillary for connection with an sce reference electrode. two electrolyte was used in this study, first one consist of condensed synthetic automotive solution [4] (csas) [ammonium nitrate (0.077 g.l-1), ammonium sulphate (1.017 g.l-1), potassium chloride (0.1345 g.l-1), ammonium hydroxide (0.33 ml.l-1) and 1m hydrochloric acid (5.8 ml.l-1)], these salts obtained from bdh chemical ltd. the ph of this solution was (3.3); the second electrolyte consist of condensed synthetic automotive solution (csas) with adding 7.3% of [54% isopropanol 20% aniline 16%toluene -10% oxygenol (50% methanol + 50% tertbutanol)] (iato) mixture [10]. potentiodynamic and cyclic polarization measurements were carried out with winking mlab 200 potentiostat from bank-elektronik with electrochemical standard cell. electrochemical measurements were performed with a potentiostat by sci electrochemical software at a scan rate 3 mv.sec-1. polarization experiments were started when the rate at which open circuit potential (eocp) changed was less and more 200mv. the main results obtained were expressed in terms of the corrosion potentials (ecorr) and corrosion current density (icorr) in addition to measure the tafel slops by tafel extrapolation method. 3. results and discussion the variation of potential with time for pure aluminium and its alloys in csas can be shown through open circuit potential values, this behavior indicate that behavior of al-mg and alcu-mg alloys more stable than pure al and al-sicu alloy with time. the open circuit potential values take the following sequence for al and its alloys: -eoc al-si-cu > pure al > al-cu-mg > al-mg the various equilibria of al–h2o system has been collated by pourbaix et.al. [11] in a potential versus ph diagram. this diagram indicates the theoretical circumstances in which aluminium should show corrosion (forming al3+ at low ph value and alo2 ¯ at high ph value), passivity due to hydragillite, i.e. al2o3.3h2o (at near – neutral ph values) and immunity (at high negative potentials). the nature of the oxide actually varies according to temperature, boehmite (al2o3.h2o) is the stable form. the potentiodynamic polarization curves for pure al and its alloys in csac in absence and presence of (iato) mixture are shown in fig. (1). these figures show the main two behavior of alloy in active region, the lower section, represent the cathodic reaction of reduction of hydrogen because of acidity the medium as follow: 2h+ + 2e → h2 …(1) while the upper section represent the anodic reaction, where the oxidation of metals in alloys, mainly aluminium, can occur according to the following reaction: al → al3+ + 3e … (2) the value of the corrosion potentials (ecorr) and corrosion current density (icorr) and tafel slops (bc , ba ) were getting directly from the potentiostat. the value of polarization resistance (rp) have been calculated from stern-geary equation [12], [13]: majid h. abdulmajeed al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 3643(2015) 38 )(303.2 )( . 0 cacorr ca ip bbi bb di de r +×× × == = …(3) where: (bc) and (ba ) are cathodic and anodic tafel slop respectively,( icorr .): corrosion current density. and the value of corrosion rate have been calculated by using the following equation [14]: .27.3)( corrr i e y mm c ρ = …(4) where: (e) equivalent weight of corroded alloy, (ρ) density of alloy. the corrosion parameters listed in table (2) show that the sequence of corrosion potential of pure al and its alloys take the following sequence: -ecorr : al-si-cu > pure al > al-cu-mg > al-mg but these results don`t agreement of the result of corrosion current density which take the following sequence: icorr :pure al < al-cu-mg < al-si-cu < al-mg the data concerned corrosion current density enhanced corrosion rate. the data of corrosion rate take the same sequence of corrosion current density. this result indicates that pure al less sensitive to corrosion than its alloys and this result agreement with the data of polarization resistance which take the following sequence: rp : pure al > al-cu-mg >al-si-cu >al-mg the corrosion parameters listed in table (2) show that addition of (iato) mixture shift corrosion potentials (ecorr) toward active direction, and shift corrosion current density (icorr) value to lower values and take the following sequence: icorr : al-si-cu = al-cu-mg < pure al < al-mg this result mean that al-alloys with si and cu content became more resistance to corrosion in fuel after adding the(iato) mixture and favor to use as fuel tank, also its known that al-alloys has mechanical properties better than pure al. the tafel slopes were very much influenced in the presence of (iato) mixture. the cathodic tafel slope (bc) were increased after adding (iato) mixture comparable to the value of (bc) with absence of (iato)to the same electrode material. but the anodic tafel slopes (ba) were varied after addition of the mixture as it shown in table (2). the small cathodic slope indicates the presence of a film on the surface of the tested material, which is less permeable and can even obstruct the metal dissolution reaction but still permits an electrochemical reaction to occur[5,6]. it is known that the surface oxide on al alloys permits the movement of ionic species and an electron or vacancy flux across it [5, 6]. determination of the nature of the cathodic process in organic solutions is extremely difficult. the proposed cathodic reaction in the ethanolgasoline fuel is oxygen reduction when no efforts were made to remove dissolved oxygen from the solutions. previous works [7] reported that the main factor affecting the corrosion rate of mild steel in the ethanol/water/sulphuric acid system is the conductivity of the medium, and the conductivity increased when the water percentage in the ethanol-water mixture increased. in present study, the film which can be presence on the surface of material forming because of the electron density on oxygen and nitrogen atoms in (iato) mixture. cyclic polarization data were recorded by m lab electrochemical laboratory system with electrochemistry software m lab sci-multi channel potentiostat. potentiodynamic measurements were carried out in order to determine the initiation and propagation of local corrosion, which is associated with the breakdown of passive protective film. figures (2) and (3) show the cyclic polarization for pure al and its alloys, figure(2) indicate that the potentials for the reverse scan curves are more negative than those for the forward scan, this results means a stable oxide film is formed during the forward scan but after adding the (iato) mixture, figure (3), gave the forward scan the same of reverse scan and show there is no chance to pitting corrosion due to the protective film which formed because of electronic density of oxygen and nitrogen atoms in components of mixture on the aluminium and its alloys surface. 4. conclusion adding of some selective organic component (7.3% of [54% isopropanol 20% aniline 16%toluene -10% oxygenol (50% methanol + 50% tertbutanol)] (iato) mixture to (csas) solution which increase the octane number as shown in previous studied, we found that this mixture also increased the corrosion resistance of pure al , al-si-cu , al-mg and al-cu-mg alloys. the rate of corrosion takes the following sequence: cr in mpy (in csas only): al < al-cu-mg< al-si-cu < al-mg majid h. abdulmajeed al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 3643(2015) 39 cr in mpy (in csas+ lato mixture): al-cumg= al-si-cu < al< al-mg enhancement of corrosion resistance due to electronic density on oxygen and nitrogen atoms in the organic component mixture. table 1, chemical composion of al-alloys. table 2, corrosion parameters of alalloys in synthetic condensed automotive solution (csas) and in synthetic condensed automotive solution in presence of iato mixture (csas+iato) at room temperature. material open circuit potential (eoc/mv) corrosion potential (ecorr/mv) corrosion current density (icorr/µa.cm-2) tafel slope (mv.dec-1) corrosion resistance x103 (rp/ω.cm2 ) corrosion rate mpy -bc +ba pure al in csas -459 -430.3 3.44 135.9 156.2 9.1851 1.4895 in csas+ iato -492 -433.1 2.94 110.7 114.4 1.5241 1.2730 al-cu-mg in csas -249 -282.1 14.07 132.3 93.2 1.6896 6.0707 in csas+ iato -484 -487.3 0.067 90.0 84.2 0.2818 0.0290 al-mg in csas -179 -203.1 78.76 170.1 98.7 0.3448 34.103 in csas+ iato -501 -500.9 22.78 119.5 125.5 0.001166 9.8637 al-si-cu in csas -585 -487.6 35.48 351.1 42.4 0.4636 15.3628 in csas+ iato -490 -487.8 0.067 88.0 82.2 0.2754 0.0290 element wt% cu wt% mg wt% mg wt% fe wt% si wt% mn wt% zn wt% ti wt% cr wt% ni wt% al al-cu-mg 3.8-4.9 1.2 – 1.8 1.168 0.5 0.5 0.0.3-0.9 0.25 0.15 0.1 bal. al-mg 0.1 4 -4.9 0.4 0.4 0.4-1 0.25 0.15 0.05-0.25 bal. al-si-cu 3.563 1.168 0.857 12.587 0.335 0.683 0.070 0.049 0.513 bal. majid h. abdulmajeed al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 3643(2015) 40 fig. 1. potentiodynamic polarization for al and its alloys in condensed synthetic automotive solution in absence and presence iato mixture . fig. 2. cyclic polarization for al and its alloys in condensed synthetic automotive solution. majid h. abdulmajeed al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 3643(2015) 41 fig. 3. cyclic polarization for al and its alloys in condensed synthetic automotive solution in the presence of iato. 5. references [1] j. r. davis, "metal handbook", second edition (1998), p. 488. [2] jaya rawat, p.v.c. rao and n.v. choudary, “effect of ethanol – gasoline blends on corrosion rate in the presence of different materials of construction used for transportation, storage and fuel tanks”, sae paper 28-0125, (2008). [3] gary mead, bruce jones, paul steevens, nathan hanson and joe harrenstein, “an examination of fuel pumps and sending units during a 4000 hour endurance test in e20”, this document is intended to outline fuel sending unit endurance testing procedures used by the minnesota center for automotive research (mncar), (2009). [4] hamilta de oliveira santos, fernando morais dos reis, clarice terui kunioshi, jesualdo luiz rossi, and isolda costa, “corrosion performance of al-si-cu hypereutectic alloys in a synthetic condensed automotive solution”, mat. res. vol.8, no.2, (2005), p.155-159. [5] traldi sm, rossi jl, costa i., “corrosion of spray formed al-si-cu alloys in ethanol automobile fuel”, key engineering materials, vols. 189-191, (2001), p.352-357. [6] traldi sm, rossi jl, costa i., “an electrochemical investigation of the corrosion behavior of al-si-cu hypereutectic alloys in alcoholic environments”, revista de metalurgia supplementos, (2003), p. 86-90. [7] x. nie, x. li, and d. northwood, “corrosion behavior of metallic materials in ethanolgasoline alternative”, fuels, materials science forum, vols. 546-549, (2007), p. 1093-1100. [8] eiman a. sheet and jehad a. yamin, “relative performance of compression ignition engine using various blend of diesel-ethanol fuel”, proceeding of 1st scientific conference of energy and majid h. abdulmajeed al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 3643(2015) 42 renewable energy applications, university of technology – energy and fuel researches center, baghdad-iraq, 2011. [9] alessandra regina pepe ambrozin, sebastião elias kuri and marcos roberto monteiro, “metallic corrosion related to mineral fuels and biofuels utilization”, quím. nova, vol.32, no.7, (2009). [10] eiman a. sheet, " improvement of gasoline octane number by blending gasoline with selective components" msc.thesis, university of technology, (2008). [11] l. l. sherir, "corrosion", metal/environment reactions, second ed., vol.1, pp. 4:12, (1976). [12] stern, m., method for determining corrosion rates from linear polarization data, corrosion, vol.14, no.9, pp.440-444, 1958. [13] stern m., and geary, a. l., “electrochemical polarization i: a theoretical analysis of the slope of polarization curves”, journal of the electrochemical society,vol.104, no.1, pp.559-563, 1957. [14] lawrence j., korb and david l. olson, “corrosion”, volume 13 of the 9th edition, “metals handbook”, fourth printing (1992). )2015( 3643، :89, 4، ا#6�د11�!+, ا#34ارز*0 ا#/.�, ا#"!+**()� '" � &%� ا#"! � 43 رة ��� �� � ا��� �ي ��� ���� ���� ت ����� ��� ������ل ا��� � ا��"# ا� '&�% أ� -, +* ا(�����م ***إ�� ن ��� إ0= ن ;�: ** -789 إ-� ��6 إ4%اھ�2 * � 1. ��0. �,. ا��/�. ا#!(*6, ا#@?.3#3) , / <=> ھ.�-, ا#"3اد * ا#!(*6, ا#@?.3#3) ,/ *e fgh?.3#3) ( ا#c(<, وا#c(<(ت ا#"@!�دة ***،** majed_hamed60@yahoo.com �ih%#0 اjوh@?#kا : chemistsulsfa_59@yahoo.com �ih%#0 اjوh@?#kا : eman_sheet@yahoo.co.uk �ih%#0 اjوh@?#kا : ا��9< اdll+& ,i3llw6# ا#=ll+3ك أ#@3ll ."#`# 0+gallم ا#.^0ll و-0llp \?])%ll ا#"3ll+8ل ا#"?yllz ا#v"llw@i 0&).llx اull"6# درا-h stlle ,ll إmll6n oifll* ,p)llq ا#"ll%gh(ت )csas (,phe#ارة اh' ,(0 درp . f^.l#ل اgh v* uga@#و*, ا)^* 0p دة)iز h/iُi ,-را�ه ا#l0 ھpن و)@gوkد ا�0 &p دة)iز ,^n),-0 دراp n +4#ا h/iُi uga@#ا ,&h< > 0p . gوh/?#ا#^ (-(ت ا �.& vg)=#6"(ل ا#"!/(د ا@-)n )اؤھh(أ <e , ]) "٣ d#إ ,p)qq)n ،, ]اh^@-kا up)e ,^ihcn uga@#ت ا) c6* v "4@# , j)s u?# r#3p 0+* .اh@%(ر ا#".d.8 اhste ,ph6"# 0^+8# ا#"(دة 0p h^.@#)n و-n اhk@%(ر 0p دة)if#3دي اs)?#ا up)e u *)bc( ,i3w6#ت ا)j3?"#ا oif* ,p)qإ �6n . ,i3دjkا up)e 3ل * v?#و)ba (n +4#ا ,p)qإ �6n re9(وe . دةإن)if#ا u * 0p fال 8n u"=e�وث up)ee ا#?(3sدي i�ل &+d و)3د wx(ء &+ucd *(دة اhk@%(ر، وا#@0 ھ0 أ<9j u(ذا وv?"i أن u&)9e u>h6e اg8jل ا#"6�ن و#?./( *( gوh/?#ا u&)9@#3. " ([0 اn f!.i أن v?"i ا ا#=+3كl3ي-(طھw6#ا#"?3ن ا n +h 0p v (وh@.#وا v !=gذرات ا}و d+& , jوh@?#kا ,p)z?#ا ,. 3851 al-khwarizmi engineering journal,vol. 12, no. gasoline, ethanol and methanol ( an alternative to conventiona sulfur and energy and renewable (received abstract iraqi conventional gasoline characterized by its low octane number not exceed 82 and high lead and sulfur content. in this paper tri-component or ternary, blends of gasoline, ethanol, and methanol presented as an alternative fuel for iraqi conventional gasoline. the study conducted by using gem blend that equals e85 blend in octane rating. the used gem selected from turner, 2010 collection. g37 e20 m43 (37% gasoline + 20% ethanol+ 43% methanol) was chosen as gem in present study. this blend used in multi emissions compared with that produced by a gasoline engine. the results show that this blend can formulate with available iraqi produced materials. gem ternary blend offers significant advantages in terms of engine performance compared to gasoline. also, gem higher useful compression ratio (hucr) = 9.25 while gasoline hucr=7.5. the increment in engine bp was brake thermal efficiency increased by 19.59%. the volumetric efficiency increased by 8.06%. also, co, hc concentrations were reduced by 30.5%, 25.16% respectively. smoke opacity concentrations reduced by 5% as well as nox concentrations that reduced by 1.75%. keywords: ternary blends, gem, performance, emissions, higher useful compression ratio. 1. introduction sulfur and lead content in iraqi gasoline is considered an environment obstacle in all criterions. many researchers studied the effect of these pollutants content in iraqi conventional petrol and defined its hazards. the u.s. energy information administration (eia) declared that sulfur content in iraqi petrol produced from basra wells increased from 1.95 % to recently at around 2.7-2.8 % sulfur content [2]. in the northern kirkuk field, sulfur content increased from 1.97 % in 1988, to above 2 % after 2003 [1 & 2]. sulfur has low ignition temperature that its presence can reduce the fuel self ignition temperature. it is found that the response of gasoline fuel to lead compounds is reduced by the presence of sulfur. khwarizmi engineering journal,vol. 12, no. 3, p.p. 3851 (2016) gasoline, ethanol and methanol (gem) ternary blends utilization as conventional iraqi gasoline to suppress emitted r and lead components to environment miqdam tariq chaichan renewable energy technology center/ university of technology email: 20185@uotechnology.edu.iq (received 19 october 2015; accepted 9 march 2016) iraqi conventional gasoline characterized by its low octane number not exceed 82 and high lead and sulfur content. component or ternary, blends of gasoline, ethanol, and methanol presented as an alternative fuel for oline. the study conducted by using gem blend that equals e85 blend in octane rating. the used gem selected from turner, 2010 collection. g37 e20 m43 (37% gasoline + 20% ethanol+ 43% methanol) was chosen as gem in present study. this blend used in multi-cylinder mercedes engine, and the engine performance, and emitted emissions compared with that produced by a gasoline engine. the results show that this blend can formulate with available iraqi produced materials. gem ternary blend offers significant advantages in terms of engine performance compared to gasoline. also, gem higher useful compression ine hucr=7.5. the increment in engine bp was 24.12%, bsfc reduced by 13.9% and brake thermal efficiency increased by 19.59%. the volumetric efficiency increased by 8.06%. also, co, hc 30.5%, 25.16% respectively. smoke opacity reduced by 46.49% and co concentrations reduced by 5% as well as nox concentrations that reduced by 1.75%. blends, gem, performance, emissions, higher useful compression ratio. sulfur and lead content in iraqi gasoline is considered an environment obstacle in all criterions. many researchers studied the effect of these pollutants content in iraqi conventional petrol and defined its hazards. the u.s. energy ion (eia) declared that sulfur content in iraqi petrol produced from basra wells increased from 1.95 % to recently at around 2.8 % sulfur content [2]. in the northern kirkuk field, sulfur content increased from 1.97 % 1 & 2]. sulfur has low ignition temperature that its presence can reduce the fuel self ignition temperature. it is found that the response of gasoline fuel to lead compounds is reduced by the presence of sulfur. thus, the presence of sulfur in the fuel wil promote knock in the engine. also, vehicles number increased significantly after the year 2003 all over iraq that resulted in an increase in lead and sulfur emissions into the air. al-khalidy [3] measured lead concentrations in 25 stations in babylon go baghdad. the measured concentrations compared to the standard limits of united states environmental protection agency (epa). the results showed that the average of measured lead concentrations during the year 2010 was (3.13 µg/m3) which was greater than epa standard limits (2 µg/m3). ismayyir clarified that iraqi gasoline production is rather stable but iraqi produced gasoline specifications needs to be improved. the al-khwarizmi engineering journal (2016) ternary blends utilization as suppress emitted environment university of technology iraqi conventional gasoline characterized by its low octane number not exceed 82 and high lead and sulfur content. component or ternary, blends of gasoline, ethanol, and methanol presented as an alternative fuel for oline. the study conducted by using gem blend that equals e85 blend in octane rating. the used gem selected from turner, 2010 collection. g37 e20 m43 (37% gasoline + 20% ethanol+ 43% methanol) was chosen linder mercedes engine, and the engine performance, and emitted the results show that this blend can formulate with available iraqi produced materials. gem ternary blend offers significant advantages in terms of engine performance compared to gasoline. also, gem higher useful compression bsfc reduced by 13.9% and brake thermal efficiency increased by 19.59%. the volumetric efficiency increased by 8.06%. also, co, hc reduced by 46.49% and co2 thus, the presence of sulfur in the fuel will promote knock in the engine. also, vehicles number increased significantly after the year 2003 all over iraq that resulted in an increase in lead and sulfur emissions into the air. khalidy [3] measured lead concentrations in 25 stations in babylon governorate southern baghdad. the measured concentrations compared to the standard limits of united states environmental protection agency (epa). the results showed that the average of measured lead concentrations during the year 2010 was (3.13 was greater than epa standard clarified that iraqi gasoline production is rather stable but iraqi produced gasoline specifications needs to be improved. the miqdam tariq chaichan al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 3851(2016) 39 improvement must continue lower values of lead and sulfur [4]. chaichan studied the emitted particulate matters (pm) and lead (pb) emissions from single cylinder spark-ignition (si) engine fueled with iraqi gasoline. the results showed that lead concentrations depend mainly on fuel quantity entering the engine in spite of any other parameter. pb concentrations increased with increasing equivalence ratio from lean to rich, increasing engine speed from low to high speeds and increasing torques from low to high [5]. table 1 represents gasoline specifications according to different standards while fig. 1 shows changes in iraqi gasoline blends’ specifications. fig. 2 represents a contour map of the pb distribution in baghdad city. table 1, gasoline specifications according to different standard [6] standards ds-ii euro iii euro iv iraq* year of implementation 20002001 2005 2010 2000 sulfur, ppm 500 150 50 500 ron, min 88 91 91 85 mon, min 81 81 benzene, max., vol.% 5/3 1 1 aromatics, max., vol.% 42 35 olefin, max., vol.% 21 21 rvp, kpa 35-60 60 max. 60 max. 4482.5 *marketing specifications of iraqi petroleum products. fig. 1. changes in iraqi gasoline blends’ specifications [4]. iraqi gasoline depends on pb compounds to enhance its octane number, but there are many additives that their addition to gasoline improves its octane rating. methanol and ethanol considered the best of these additives due to its advantages including energy density, distribution infrastructure compatibility and the possibility of efficiency improvement and pollutant emissions reduction [8]. in spite of all its benefits whether on combustion or emissions, ethanol is known to be aggressive to certain materials used in the vehicle fuel systems construction [9]. in the recent study, the concept of the ternary blend reviewed, and the results of engine performance and emitted emissions reported. the use of ternary blends introduced as an improved advancement to reduce the dependence on iraqi gasoline with it has high levels of sulfur and lead. fig. 2. contour map shows the pb distribution in baghdad [7]. fig. 3. family of isostoichiometric gem blends equivalent to conventional e85 [14]. miqdam tariq chaichan al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 3851(2016) 40 the fuel blending concept used in the tests to limit the biomass quantity used to produce ethanol by co-blending it with both methanol and gasoline. turner first introduced this concept in a conference presentation [10]. a detailed published study as sae paper followed this presentation [11]. this concept can describe as a ternary blend of gasoline; ethanol and methanol can replace a binary gasoline-ethanol mixture (such as e85). this replacement depends on the volume fraction of each component in a way to yield the same stoichiometric air-fuel ratio (afr). afr for e85 is 9.7:1 depending on the used gasoline, so a family of equivalent ternary blends can be created [12]. here, the consideration of two prominent borders like the term g15 e85 m0 that can substitute by g44 e0 m56 and between these two limits a description of a family of blends as gem blends [13]. turner et al. put a diagram (fig. 3) specifies the equivalences that must be used to derive any e85-equivalent blend. when one charts a vertical line, the proportions of the individual blend components read from the y-axis where this line crosses the boundaries between them. all of the isostoichiometric blends have essentially identical volumetric energy content (based on the masses and densities of the individual components) [10 & 11]. also, any vertical line drawn gives a ternary blend with different percentages of gasoline, ethanol, and methanol. these blends limit and reduce the need for high quantities of ethanol, which means reducing its side effects. besides, a large part of gasoline replaced with methanol that is a better from an energy security viewpoint [14]. the ternary blend suggested by turner believed to have the potential to function in iraq due to the possibility of producing ethanol and methanol from sustainable sources. there is no need for additional infrastructures. many studies showed that gem ternary blends formulated with a high proportion of methanol can be cheaper than gasoline on a cost per unit energy basis [15 & 16]. this study aims to provide a practical alternative for iraqi gasoline that can suppress emitted sulfur and lead components to the environment. the usage of ethanol and methanol is a realistic since both can be produced from sustainable resources that are available in iraq, or from natural gas and petroleum resources that iraq is one of the main reservoirs of these materials in the world. 2. experimental setup 2.1. apparatus two engines used in the recent study. the first one is a spark ignition engine type (prodit gr306/0001) which was used to evaluate the using blends higher useful compression ratio at optimum spark timing. prodit engine is water cooled, single cylinder, four strokes, and variable compression ratio. figs (4 a & b) represents the general arrangement of the experimental rig while table 2 illustrates engine specifications. fig. 4a. single cylinder prodit spark ignition engine. fig. 4b. single cylinder prodit spark ignition engine. the engine rig coupled to an air tank that damped out the pressure variations in the entering air to the carburetor. the volume of the air drawn measured with the aid of a manometer that translates the pressure drop across an orifice. this set calibrated in the laboratory. the engine supplied fuel comes from the main fuel tank passing through a graduated measuring fuel gauge (burette). the engine output torque measured using a hydraulic dynamometer. this dynamometer calibrated in the laboratory miqdam tariq chaichan al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 3851(2016) 41 employing calibrated weights. the exhaust gas temperature measured using several thermocouples type k at the beginning of the exhaust tube. the thermocouples calibrated in the laboratory by comparing its readings with that of a set of calibrated thermocouples. table 2, prodit engines specifications. manufacturer prodit no load speed range 500-3600 rpm (otto cycle ) cycle otto or diesel, four strokes load speed range 1200-3600 rpm (otto cycle) number of cylinder 1 vertical intake star 54o before t.d.c diameter 90mm intake end 22o after t.d.c stroke 85mm exhaust start 22o before t.d.c compression ratio 4-17.5 exhaust end 54o after t.d.c max .power 4 kw 2800 rpm fixed spark advance 10o (spark ignition) max .torque 28 nm at 1600 rpm swept volume 541cm3 fig. 5. the experimental rig of si mercedes engine. the second spark ignition engine was mercedes-benz type, and it was used in the recent study to evaluate the effect of ternary blend fuels on engine performance and emissions. this engine was used in the tests because it represents a wide range of the cars engines in iraq streets. this engine has 2 liters displacement volume, water cooled, 4-strokes and 4 cylinders. a hydraulic dynamometer coupled to the engine used to measure the brake torque. fig. 5 shows the experimental rig of the engine, and table 3 lists the main technical specifications of this engine. this engine selected to the study due to its closeness to the majority of the vehicle’s engines used in iraq. table 3, the main technical specifications of the mercedesbenz 200 ce-16 engine. item specification engine 4-cylinder-inline engine (four-stroke) displacement 2 liters the production year 1992 fuel system carburetor cooling water the piston stroke length 78.70 mm the cylinder diameter 89.90 mm the compression ratio 9.60:1 the maximum power delivered by the engine 100 kw at 5500 rpm maximum torque 190 nm at 4000 rpm 2.2. emission analyzing nox, co, co2 and hc emissions were measured by using gas analyzer type hg-550. the calibrations reading for this measuring device obtained from the factory inspection sheet produced by hephzbah co. ltd at 16/10/2013 since it is a new appliance. smoke analyzer type "mod .smoky" used to measure smoke opacity in the recent study. the working principle of this device is the usage of optic absorption of the smoke. a halogen lamp provides the bright of light. the electric signal generated by an optical sensor is electrically conditioned and computed by a microprocessor and then displayed as absorption % vol. the smoke analyzer calibrated in the central organization for measuring and quality control labs. the engine noise measured employing a precision sound pressure level meter supplied with microphone type 4615. the device calibrated employing a standard calibrator type pisto phone 4220. fig. 6 shows the sniffer l-30 device used to collect the emitted pms. pms collected using whatmann-glass micro-filters. the filters weighed before and after the sampling operation that extend for one hour. each filter saved in plastic bag temporarily at the end of collecting samples operation until weighing and analyzing the results. atomic spectrum absorption system was used to evaluate lead concentrations in particles samples manufactured by shimadzu miqdam tariq chaichan company type (aa-6200) made in japan. represents this system. fig. 6. drawing air equipment to collect pm type sniffer fig. 7. the system used in evaluating of pb concentrations in particulates (the atomic spectrum absorption system) the following equations used to calculate the engine performance parameters [17]: 1brake power �� � ��∗�∗� ∗� � 2brake mean effective pressure ���� � �� � �∗ ���∗� �/�� 3fuel mass flow rate �� � � ���� �� � � �� �� ! " #�$% the tested fuels densities (ρf) were measured in the al-doura refinery labs. 4air mass flow rate al-khwarizmi engineering journal, vol. 12, no. 42 6200) made in japan. fig. 7 rawing air equipment to collect pm type in evaluating of pb tomic spectrum the following equations used to calculate the engine performance parameters [17]: …. (1) …. (2) % …. (3) were measured in �� &,&(�. � ��*+,∗ .-. / � 0&�1 �� &234,. � 56.7 � � ∗� � 0 5brake specific fuel consumption �#8$ � � �9: � 3600 >? >@.+1 6total fuel heat a� � �� � � bc5 � 7brake thermal efficiency d9�+. � 9:e2 � 100 % 8equivalence ratio [18]: ∅ � ijk ilmnk� iok piok/ilmnkq�2 � irk irk/ilmn s ijkilmnkt�2 2.3. materials two iraqi gasoline with on=82 & 77 produced by al-doura refinery used in the recent study. iraqi gasoline characterized by its low octane number and high lead content. the gasoline properties obtained from in the refinery fuel laboratory. gasoline with 82 on used as a reference fuel for comparison because it is the conventional fuel i with 77 on utilized in the e85 and ternary blends because it is unleaded fuel. ethanol (99.7% purity) employed in this work. it was distillated from iraqi drink named (araq) for several times to purify it from any residuals. e85 (85% 15% gasoline) blended fuel prepared by mixing the ethanol (85% by volume) with gasoline (77 on). methanol characterized by its separation where it can fall out of solution when it is being blended with gasoline in the absence of any dedicated co-solvent methanol-gasoline phase separation but without blending for constant stoichiometry, his result shows that this phenomenon depends on ambient temperature, and it occurs with degrees less than −15°c. iraqi ambient temperatures d to this extent even in the north of iraq where high mountains and lower temperature degrees. ethanol reduces separation trend of methanol. methanol mixed first with ethanol, and then it blended with gasoline. table 4 typical properties of the used materials. khwarizmi engineering journal, vol. 12, no. 3, p.p. 3851(2016) &�1 >?6!( …. (4) 0&�1 >?6!( …. (5) brake specific fuel consumption 1 …. (6) brake thermal efficiency …. (7) : lmnk�2 ….. (8) iraqi gasoline with on=82 & 77 doura refinery used in the recent . iraqi gasoline characterized by its low octane number and high lead content. the gasoline properties obtained from in the al-doura fuel laboratory. gasoline with 82 on used as a reference fuel for comparison because it is the conventional fuel in iraq while gasoline with 77 on utilized in the e85 and ternary blends because it is unleaded fuel. ethanol (99.7% purity) employed in this work. it was distillated from iraqi drink named (araq) for several times to purify it from any residuals. e85 (85% ethanol– 15% gasoline) blended fuel prepared by mixing the ethanol (85% by volume) with gasoline (77 on). methanol characterized by its phase separation where it can fall out of solution when it is being blended with gasoline in the absence of solvent. qi [20] studied gasoline phase separation but without blending for constant stoichiometry, his result shows that this phenomenon depends on ambient temperature, and it occurs with degrees less than 15°c. iraqi ambient temperatures do not reduce to this extent even in the north of iraq where high mountains and lower temperature degrees. adding ethanol reduces separation trend of methanol. methanol mixed first with ethanol, and then it table 4 represents the cal properties of the used materials. miqdam tariq chaichan al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 3851(2016) 43 table 4, the specifications of gasoline, ethanol, methanol and the tested blends [14] fuel component gasoline ethanol methanol formula various c2h5oh ch3oh stoichiometric afr 14.18 8.96 6.44 density (kg/l) 0.731 0.789 0.791 gravimetric lhv (mj/kg) 43.12 26.80 19.90 volumetric lhv (mj/l) 31.52 21.15 15.75 carbon intensity (gco2/l) 2297.3 1509.7 1088.0 carbon intensity (gco2/mj) 72.88 71.38 69.10 ron (to astm d2699) 95.3 108.6 108.7 mon (to astm d2700) 85.0 89.7 88.6 sensitivity 10.3 18.9 20.1 the fuel sensitivity (ron-mon) clarifies the fuel antiknock trend where higher fuel sensitivity means higher knock resistance. paraffin fuel tends to have low sensitivity while olefins, aromatics, diolefins, napthenes, and alcohols tend to be high sensitive fuels. table 4 declares that methanol has the maximum sensitivity between the tested fuels and ethanol follows it. the differences between the sensitivities of these two alcohol fuels and gasoline are large indicating higher knock resistance. from fig. 3 it can be seen that e85 contains no methanol; the binary equivalent for it consist of gasoline and methanol mixture occurs at m56. in turner works [10, 11 & 14] the first described blend (g15 e85 m0), the second blend (g44 e0 m56) and the equivalent to e85 or the third blend (g29.5 e42.5 m28). in the recent study, ethanol limited as possible as a result of using no flexengines that resist its aggressive effects. however, if for any reason, the supplied bio-ethanol prevented. as for a reduction in feedstock supply, or legislations that avoid the use of ethanol due to its interrupt with the food chain. one can exchange the limited amount of ethanol introducing methanol in a ternary blend instead of it. the blend used in this study was (g37 e20 m43) where gasoline with 77 on used. all isostoichiometric ternary blends mentioned above embrace correspondent volumetric energy content (based on the masses and densities of the individual components). as the rightand lefthand edges demonstrate a stoichiometric afr of 9.7:1 (i.e. e85 and m56, respectively) [11]. table5 illustrates the compositions of e85 and the ternary blend used in the recent study and their properties. all these properties measured in aldoura refinery laboratories. table 5, the compositions of the tested ternary blends fuels and their properties. fuel component gasoline e85 g37 e20 m43 stoichiometric afr 14.98 9.69 9.71 density (kg/l) 0.731 0.781 0.769 gravimetric lhv (mj/kg) 43.12 29.09 29.56 volumetric lhv (mj/l) 31.52 22.71 22.71 carbon intensity (gco2/l) 2297.3 1627.9 1623.9 carbon intensity (gco2/mj) 72.88 71.69 71.49 ron (to astm d2699) 82 97.4 96.4 mon (to astm d2700) 75.0 85.7 85.3 sensitivity 07.3 11.7 11.1 the sensitivity of the tested gem is close in magnitude to e85 ones indicating similar knock resistance. 2.4. error analysis to ensure the reality of the results within an experimental uncertainty of (95% confidence level), and to confirm repeatability, the experiments conducted three times at least for each set of tests. the averaged value used in the analysis. this procedure employed in all measurements because some degree of uncertainty that may come from a variety of sources. the evaluating process of this uncertainty correlated with measurements. an estimate of the level of confidence associated with the value gives the complete statement of a measured value. table 6a & b represent the experimental accuracies of the measuring devices used in the study. the uncertainty measuring procedure illustrated in reference [19] used, and the uncertainty for present tests was: �u � ip0.2q� + p1.17q� + p0.46q� + p1.1q� + p0.69q� + p0.22q� + p1.4q� + p0.26q� + p0.92q� + p0.7q� + p0.93q� + p0.022q� + p0.3q�k .. = ±2.77% miqdam tariq chaichan al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 3851(2016) 44 table 6a, experimental accuracies for prodit engine rig. measurements accuracies in this study thermocouples ± 0.2 % engine speed tachometer ± 1.17% fuel flow meter ± 0.46 % air flow meter ± 1.1 % dynamometer ± 0.69% table 6b, experimental accuracies for mercedes benz engine rig measurements accuracies in this study thermocouples ± 0.22 % engine speed tachometer ± 1.4% fuel flow meter ± 0.26 % air flow meter ± 0.92 % sound pressure level measurement ± 0.7 dynamometer ± 0.93% emitted exhaust gasses concentrations measurement ± 0.022 smoke opacity meter ± 0.3 2.5.test procedure the first set of test was conducted using single cylinder prodit engine to evaluate the exact higher useful compression ratio (hucr) for e85 and gem blends. the second round of tests conducted using multi-cylinders mercedes engine. all tests carried out under steady state operating conditions at various engine speeds. engine torque was fixed when the engine was run at variable speeds to evaluate its effect on performance and emissions. a spark ignition engine running on gem (ethanol and methanol blended with gasoline) performance and emission characteristics assessed and compared with a conventional iraqi gasoline of on=82. the daily procedure employed was: 1. drain tank and fuel system completely at the end of each test. 2. prepare the test blend and fill the engine with 25 liters of the new test fuel blend. this procedure was used to ensure the homogeneity of the blend and prevent the reaction of ethanol with water vapor. 3. the engine allowed warming up for 20–30 min. this time was sufficient for the engine to consume the remaining fuel from the previous experiment also. 4. the dynamometer control was used to obtain the required engine load. the engine speed, fuel consumption, and load were measured while the brake power, brake torque and brake specific fuel consumption (bsfc) were computed. 5. for each test case, three runs performed and an average value obtained from the experimental data. 6. after the engine achieved the steady state, co, co2, hc, and nox concentrations measured by exhaust gas analyzer, while the smoke opacity recorded from the smoke meter. 3. results and discussions the first set of tests conducted with the prodit engine to evaluate the higher useful compression ratio (hucr) for the tested fuels. fig. 8 shows the effect of variable compression ratios on resulted brake power (bp) for a broad range of engine speeds for gasoline fuel of octane number (on) = 82. brake power increased with increasing cr till cr=7.5, at cr=8 the behavior changed, and knocking took place. engine knock causes engine vibration, loud noise, and brake power drop. engine load was forced to be reduced to prevent knock; that is why the curve dropped at engine speeds higher than 1750 rpm. the results of the figure indicate that the hucr for iraqi conventional gasoline is 7.5. fig. 9 illustrates the effect of cr when e85 used. the results manifest achieving higher brake power and higher compression ratios without knock occurrence. these findings indicate that e85 has higher octane rating compared to gasoline. the hucr for e85= 9.25 where at cr= 9.5 knock happened. this cr (9.25) is less than that evaluated by (turner, 2010) due to the used gasoline. turner used gasoline of on=95 while the gasoline used in this study was of on= 70. fig. 8. compression ratio effect on resulted engine brake power for wide range of speeds fueled with conventional iraqi gasoline. 0 1 2 3 4 5 6 1000 1500 2000 2500 b ra ke p ow er (k w ) engine speed (rpm) gasoline, on= 82, ost, 15 nm cr=5:1 cr=6:1 cr=7:1 cr=8:1 cr=7.5:1 miqdam tariq chaichan al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 3851(2016) 45 fig. 9. compression ratio effect on resulted engine brake power for wide range of speeds fueled with e85. using gem with the selected volumetric ratios gave the same results as similar to e85, which indicates a correct choice as fig 10 manifests. the hucr for gem is 9.25 equaling that for e85. methanol has superior knock resistance because of its additional cooling effect due to its high latent heat of vaporization. it is possible to achieve higher compression ratios using better octane rating gasoline. the gasoline of on=70 used because it is unleaded fuel. these results confirm that gem blends have a bigger advantage over gasoline because it prevents knock more than gasoline. fig. 11 represents a comparison between the higher useful compression ratios for the tested fuels. as the e85 and gem curves approach one another gasoline curve diverge away from them. this result indicates that using proposed gem fuel gives a fuel with a better octane rating that is suitable for the high compression ratio engines. gem blend has the similar knocking behavior of e85. the ternary blends equivalent to e85 blend is close to pure ethanol that explains this high knock resistance. fig. 10. compression ratio effect on resulted engine brake power for wide range of speeds fueled with gem ternary fuel fig. 11. comparison between brake powers resulted from using the hucr for the three tested fuels. the gem fuel used in the second set of tests to operate a four cylinders mercedes engine to evaluate the engine performance and emissions. fig. 12 represents a comparison between tested gem and iraqi conventional fuel when both fueled the mercedes engine. the octane rating and knock resistance for gem fuel is higher than that for gasoline which made the engine run at higher brake powers. the increment in bp for the tested range was 24.12% when gem was used compared with gasoline. fig. 12. wide range of engine speeds effect on resulted engine brake power when fueled with conventional iraqi gasoline and gem ternary fuel bsfc considered as the main disadvantage of fuels containing alcohols due to their lower lhv compared to gasoline. however, increasing bp reflects in reducing bsfc as equation 6 indicates and as fig. 13 shows. gasoline engine needs more fuel consumption to achieve the maximum bp while gem blend displays less bsfc to reach to its maximum loads at each speed. the reduction in bsfc was 13.9% when gem was used compared with gasoline. 2 2.5 3 3.5 4 4.5 5 5.5 6 1000 1500 2000 2500 b ra ke p ow er (k w ) engine speed (rpm) e85, ost, 15 nm cr=7:1 cr=8:1 cr:9:1 cr=9,25:1 cr=9.5:1 2 2.5 3 3.5 4 4.5 5 5.5 6 1000 1500 2000 2500 b ra ke p ow er (k w ) engine speed (rpm) g37 e20 m43, ost, 15 nm cr=8:1 cr:9:1 cr=9.25:1 cr=9.5:1 2 3 4 5 6 1000 1200 1400 1600 1800 2000 2200 2400 b ra ke p ow er (k w ) engine speed (rpm) 15 nm, ost gasoline on=82, cr=7.5:1 e85, cr= 9.25:1 (g37 e20 m43), cr=9.25:1 20 25 30 35 40 45 1000 1200 1400 1600 1800 2000 2200 2400 b ra ke p ow er (k w ) engine speed (rpm) maximum load gasoline (g37 e20 m43) miqdam tariq chaichan al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 3851(2016) 46 fig. 13. wide range of engine speeds effect on resulted engine brake specific fuel consumption when fueled with conventional iraqi gasoline and gem ternary fuel increasing bp and reducing bsfc caused the brake thermal efficiency for gem blend at a range of tested engine speeds to increase compared to gasoline as fig. 14 illustrates. it is clear that the gem blend displays significant efficiency increments. the ethanol and methanol have higher burning velocities and smaller in-cylinder cooling losses. in addition to the increase of the delivered torque due to the higher octane rating of gem blend. the increment was 19.59% when gem was used compared with gasoline. fig. 14. wide range of engine speeds effect on resulted brake thermal efficiency when fueled with conventional iraqi gasoline and gem ternary fuel. fig. 15. wide range of engine speeds effect on resulted volumetric efficiency when fueled with conventional iraqi gasoline and gem ternary fuel. ethanol and methanol as oxygenated alcohols have oxygen in their structure. this oxygen increased the volumetric efficiency for gem when compared with gasoline as fig. 15 clarifies. also, the rise in the volumetric efficiency with engine speed at maximum torques can be explained by the ascending in brake thermal efficiency with engine speed. more fuel is needed to achieve torque output. the increment was 8.06% when gem was used compared with gasoline. gem blend characterized by its lower heating value compared to gasoline. this character caused lower exhaust gas temperature for the most of tested engine speed range as fig. 16 reveals. for the engine speed range from 2200 to 2500 gem exhaust gas temperatures preceded gasoline one due to the high engine speed and its operation at maximum loads. this increment reduced the overall reduction to 1.85% when gem was used compared with gasoline. fig. 16. wide range of engine speeds effect on resulted engine exhaust gas temperatures when fueled with conventional iraqi gasoline and gem ternary fuel. 3 4 5 6 1000 1500 2000 2500 bs fc (l /h ) engine speed (rpm) maximum load gasoline (g37 e20 m43) 40 41 42 43 44 45 46 1000 1200 1400 1600 1800 2000 2200 2400 v ol um et ric e ffi ci en cy (% ) engine speed (rpm) maximum load gasoline (g37 e20 m43) 300 320 340 360 380 400 420 440 1000 1200 1400 1600 1800 2000 2200 2400 e xh au st g as te m pe ra tu re s (° c ) engine speed (rpm) maximum load gasoline (g37 e20 m43) 15 17 19 21 23 25 1000 1200 1400 1600 1800 2000 2200 2400 b ra ke th er m al e ffi ci en cy (% ) engine speed (rpm) maximum load gasoline (g37 e20 m43) miqdam tariq chaichan al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 3851(2016) 47 fig. 17. wide range of engine speeds effect on resulted co concentrations when fueled with conventional iraqi gasoline and gem ternary fuel the higher volumetric efficiency added to higher oxygen content in the gem structure caused a considerable reduction in co concentrations, as fig. 17 elucidates. the decrease in these concentrations was 30.5% when gem was used compared with gasoline. the same effect observed on hc concentrations for the same reasons as fig. 18 expounds. using gem as fuel reduced hc concentration about 25.16% compared with using conventional iraqi gasoline. fig. 18. wide range of engine speeds effect on resulted unburnt hydrocarbons concentrations when fueled with conventional iraqi gasoline and gem ternary fuel co and hc reductions mean better combustion that resulted in higher co2 concentrations, as fig. 19 indicates. co2 concentrations for gem increased but still lower than that emitted by gasoline. the reduction in co2 concentrations was 5% when gem was used compared to gasoline. thus, if the methanol produced from natural feedstock process, a much more attractive fuel exists. fig. 19. wide range of engine speeds effect on resulted co2 concentrations when fueled with conventional iraqi gasoline and gem ternary fuel gasoline has significant trends to form nox due to its slight peak temperature rise. gem engines produced relatively lower nox concentrations, as fig. 20 represents. alcohol fuels with its lower combustion temperatures handle the resulted lower nox emissions. so, although gem engine operated at higher loads due to its high resistance to knock, the combustion heat generated inside combustion n chamber still less than that of gasoline due to lower blend heating value compared to gasoline. the reduction in nox concentrations was limited to 1.75% when gem was used compared with gasoline. fig. 20. wide range of engine speeds effect on resulted nox concentrations when fueled with conventional iraqi gasoline and gem ternary fuel smoke opacity depends mainly on oxygen abundance; that is why gem engine emitted lower smoke compared to gasoline, as fig. 21 indicates. the oxygen content in gem fuel reduced all combustion emissions. the reduction was 46.49% when gem was used compared with gasoline. 0 1 2 3 4 5 6 1000 1200 1400 1600 1800 2000 2200 2400 c o c on ce nt ra tio ns (% vo l.) engine speed (rpm) maximum load gasoline (g37 e20 m43) 15 20 25 30 35 40 1000 1200 1400 1600 1800 2000 2200 2400 h c c on ce nt ra tio n (p pm ) engine speed (rpm) maximum load gasoline (g37 e20 m43) 8 9 10 11 12 13 1000 1200 1400 1600 1800 2000 2200 2400 c o 2 co nc en tr at io ns (% v ol .) engine speed (rpm) maximum load gasoline (g37 e20 m43) 580 600 620 640 660 680 700 1000 1200 1400 1600 1800 2000 2200 2400 n o x co nc en tr at io ns (p pm ) engine speed (rpm) maximum load gasoline (g37 e20 m43) miqdam tariq chaichan al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 3851(2016) 48 fig. 21. wide range of engine speeds effect on resulted smoke opacity when fueled with conventional iraqi gasoline and gem ternary fuel a higher heat release inside the combustion chamber means higher elevated combustion pressures that result in higher combustion noise. gem engine with lower combustion pressure due to the lower heating value produced lower engine noise with about 3.58% compared with the gasoline engine as fig. 22 reveals. increasing engine speed needs to increase the delivered fuel, as a result, increase emitted lead concentrations from gasoline engine as fig. 23 represents. on the other hand, gem blend emitted no lead where its components are lead-free. this result attached an important issue for the iraqi environment, and it is the aim of this study. the objective is to save iraq environment from high lead concentration due to the utilization of conventional gasoline. fig. 22. wide range of engine speeds effect on resulted noise when fueled with conventional iraqi gasoline and gem ternary fuel. fig. 23. wide range of engine speeds effect on lead concentrations when fueled with conventional iraqi gasoline and gem ternary fuel 4. conclusions the experimental tests have successfully underlined the potential of ternary blends to provide an alternative fuel for iraqi conventional gasoline fuel. the tests results indicate that blends can formulate with available iraqi produced materials. gem ternary blends offer significant advantages in terms of engine performance compared to gasoline. in the first tests set with the single cylinder engine, the results declared that the hucr for gasoline (82) = 7.5, hucr for e85=9.25, and hucr for the tested gem=9.25. the second set of tests using the multi cylinders engine, the results clarified that using gem caused: • bp increased by 24.12% due to higher octane rating. • bsfc reduced by 13.9% and brake thermal efficiency increased by 19.59%. • volumetric efficiency increased by 8.06% due to ethanol and methanol oxygen content. this content caused gem ternary blends offer significant advantages in terms of emitted engine emissions compared to gasoline, where co concentrations reduced by 30.5%, hc concentrations reduced by 25.16% and smoke opacity reduced by 46.49%. co2 concentrations reduced by 5% as well as nox concentrations that reduced by 1.75%. 0 0.02 0.04 0.06 0.08 0.1 1000 1200 1400 1600 1800 2000 2200 2400 s m ok e op ac ity (% v ol .) engine speed (rpm) maximum load gasoline (g37 e20 m43) 74 76 78 80 82 84 86 1000 1200 1400 1600 1800 2000 2200 2400 s ou nd p re ss ur e le ve l ( db ) engine speed (rpm) maximum load gasoline (g37 e20 m43) 0 2 4 6 8 10 12 14 1000 1200 1400 1600 1800 2000 2200 2400 le ad c on ce nt ra tio ns (µ g/ m 3 ) engine speed (rpm) maximum load gasoline (g37 e20 m43) miqdam tariq chaichan al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 3851(2016) 49 notation it injection timing cn cetane number di direct injection n engine speed (rpm) t engine torque vsn swept volume °btdc degree before top dead centre bmep brake mean effective pressure bte brake thermal efficiency ca crank angle cr compression ratio ubhc unburnt hydrocarbon co carbon monoxide co2 carbon dioxide nox nitrogen oxides db decibel lcv lower calorific value 5. references [1] rameshni m, parsons p e w , regulation effects on sulfur removal facilities, sulfur recovery symposium, aiche’s 5th international conference, march 10-14, 2002 [2] eia, iraq country analysis brief, 2005. available at: http://www.eia.doe.gov/cabs/iraq.html (1 of 20) [3] al khalidy kh s h, chabuk a j a, kadhim m m a, measurement of lead pollution in the air of babylon governorate/iraq during year 2010, world academy of science, engineering and technology, vol. 6, 2012 [4] ismayyir d k and dawood l m, assessment of gasoline major quality parameters, the sixth jordan international chemical engineering conference, jichec06, amman, jordan, 2012. [5] chaichan m t, experimental evaluation of the effect of some engine variables on emitted pm and pb for single cylinder sie, association of arab universities journal of engineering science, vol. 2, no. 20, pp: 113, 2013. [6] anurag a. gupta a a, automotive fuel specification in india –the journey & path forward, indo-japanese conference on fuel quality & vehicular emissions-2009. organized by bis &petrofed india habitat centre, new delhi.17-18 march, 2009. [7] habib r h, awadh s m and muslim m z, toxic heavy metals in soil and some plants in baghdad, iraq, journal of al-nahrain university, vol. 15, no. 2, pp:1-16, 2012, [8] casier b, experimental research on the behavior of alcohols and mixtures with alcohols as fuel for spark ignition engines, msc, ghent university, ghent, belgium, 2013. [9] chaichan m t, evaluation of the effect of cooled egr on knock of si engine fueled with alternative gaseous fuels, sulaimani journal for engineering science, vol. 1, no. 1, pp: 7-15, 2014. [10] turner j w g and pearson r j, using methanol to break the biomass limit of ethanol, biofuels east 2010 conference, cambridge, uk, 17th march, 2010. [11] turner j, pearson r, purvis r, dekker e, gem ternary blends: removing the biomass limit by using isostoichiometric mixtures of gasoline, ethanol and methanol, sae technical paper 2011-24-0113, 2011, doi: 10.4271/2011-24-0113. [12] anderson j e, kramer u, mueller s a and wallington t j, octane numbers of ethanol and methanol gasoline blends estimated from molar concentrations, energy fuels, vol. 24, pp: 6576-6585, 2010, doi: 10.1021/ef101125c. [13] brusstar m and gray c, high efficiency with future alcohol fuels in a stoichiometric medium duty spark ignition engine, sae technical paper 2007-01-3993, 2007, doi:10.4271/2007-01-3993. [14] turner j w g, pearson r j, mcgregor m a, ramsay j m, ben-iosefa e d, dolan g a, johansson k and bergström k, gem ternary blends: testing iso-stoichiometric mixtures of gasoline, ethanol and methanol in a production flex-fuel vehicle fitted with a physical alcohol sensor, sae paper no. 2012-01-1279, 2012. [15] turner j w g, pearson r j, bell a, de goede s and woolard c, iso-stoichiometric ternary blends of gasoline, ethanol and methanol: investigations into exhaust emissions, blend properties and octane numbers, sae paper no. 2012-01-1586, 2012. [16] anderson j, leone t, shelby m, wallington t et al, octane numbers of ethanol-gasoline blends: measurements and novel estimation method from molar composition, sae technical paper 2012-01-1274, 2012, doi:10.4271/2012-01-1274. [17] keating e l, 2007, applied combustion, 2nd eddition, taylor & francis group, llc. miqdam tariq chaichan al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 3851(2016) 50 [18] abdul haleem s m, theoretical and experimental investigation of engine performance and emissions of a four strokes spark ignition engine operated with hydrogen blended gasoline, ph d thesis, college of engineering, al-mustansiriya university, baghdad, iraq, 2007. [19] ashrea giude line. guide engineering analysis of experimental data, guideline 21986. [20] qi d h, liu sh q, liu j c and bian y zh, properties, performance, and emissions of methanol gasoline blends in a spark ignition engine, proc. instn mech. engrs journal of automotive engineering, vol. 219, part d, pp: 405-412, 2005. �� 3، ا���د12���� ا���ارز�� ا������� ا����� � �ام ط�رق ����ن �� ،51-38 )2016( 51 01� / ��.�د ) gem(�ا���زو��وا, *�"�ل وا���*�"�ل ا�)��ام '&%$ #�!"! � ا���زو��ا��!ا.� �) ��/ ��6"�ت ا�06! 5 وا�!��ص ا����0*� ا�3 ا��2�0 �ام ط�رق ����ن� �ت ا�����دة���� وا��� ا���*+ ا��%$#�#"! / *()' &%$#�#"!� ا� uotechnology.edu.iq@20185:ا�0(/� ا.�%�(و-, ا��&�� 89�ض ر��5 ا.و)��-, ا�4ي 2 /���وز -�: ,�h, ھ4ة ا��راf& e ا�9�eام . وار&8�ع *�b#اه *; ا�%0(/@ وا�(?�ص ٨٢/��!' و�#د ا���زو�!; ا�+(ا �زو�!; ا�+(ا�, ا��ij!�ي�i� k/�0( ل#-�m!ل وا��#-�m/.زو�!; وا�0�ت أو o!ip &!(-(ي *%#ن *; ا��()* rsr ;* ن#%* o!ip .eا��را @�& o!ip �9ام�e�: gem o!i9� ,-��وي t& ,h$!8 ا�#)�u*e85 . o!ip ر�!�pا f&gem v#��* ;*turner, 2010 . o!ip )!�pا �jihg37 e20 m43 )٣٧ % �-#ل % ٢٠+ "�زو�!; m/ل% ٤٣+ ا#-�m!* ( !��bا� eا��را ,h . ر اداء�j* @�&س و�!e)* ت -#ع��#ا-e.ك *�+�د ا)b* ,h o!i9�9ام ھ4ا ا��eا f& �ت ا��i�: 5$v m+0$^ ا�$�&� b* ;v(ك "�زو�!;r#iك وا��)bا��. h#�* !��زو�!;:!$@ ا�$��a` أ-k!%_& ;%�/ 5 ھ4ا ا�o!i9 *; *#اد v(ا����ر :j* ك)bأداء ا�� ��b� 0!(ة( �aا#h o!i9ھ4ا ا� )h#/0 . (ة، وuإن � �5 ھ, !i+ا� +h��ط ا�$ef-.0 ٩.٢٥اu$ھ4ة ا� @-��زو�!; )�i� �٢٤.١٢)�� ازدادت ا��jرة ا���b: !b0%ود . ٧.٥، :!$�% ,b0%ا�� ,v#$ك ا�sk�e.ا kّ�، وّ �ت %. ٨.٠٦ازدادت ا�8%�ءة ا��b: !��bود %. ١٩.٥٩ر/ ا���b: !b0%ود وازدادت ا�8%�ءة ا�b(ا %١٣.٩:�bود r#i* '!(ا)& @i� ^�4(co وhc �ن :�bود . niv ا��#ا�,% ٢٥.١٦و ٣٠.٥:�bود pا�� *��v @i�� &(ا)!' % ٤٦.٤٩وkim*وco2 ود�b: @i�� &(ا)!' % ٥�$!:nox @i� �jh١.٧٥.% (microsoft word \307\315\343\317 \344\307\355\3351-12) al-khwarizmi engineering journal al-khwarizmi engineering journal,vol. 13, no. 4, p.p. 111 (2017) effect of optimal shot peening time on fatigue life for aluminum alloy 6061-t651 ahmed n. al-khazraji department of mechanical engineering/ university of technology email: dr_ahmed53@yahoo.com (received 2 january 2016; accepted 10 may 2017) https://doi.org/10.22153/kej.2017.05.001 abstract the compressive residual stresses generated by shot peening, is increased in a direct proportional way with shot peening time (spt). for each metal, there is an optimum shot peening time (o.s.t) which gives the optimum fatigue life. this paper experimentally studied to optimize shot peening time of aluminium alloy 6061-t651 as well as using of and analysis of variance (anova). two types of fatigue test specimens’ configuration were used, one without notch (smooth) and the other with a notch radius (1,25mm), each type was shot peened at different time. the (o.s.t) was experimentally estimated to be 8 minutes reaching the surface stresses at maximum peak of -184.94 mpa. a response surface methodology (rsm) is presented to optimize the surface properties of fatigue life due to effect of two parameters (shot peening time and fatigue stresses). a statistical software was used to perform analysis of variance (anova) to predict the optimum shot peening time. the results were 8.007 minutes without notch and 7.53 minutes with notch. two 2nd degree polynomials were obtained for the two studied cases with confidence level of 95%. experimentally26.67% enhancement in fatigue life was obtained, but after using (rsm), the results gave 61% improvement, compared with ref. [2]. keywords: shot peening, fatigue life, rsm & anova. 1. introduction shot peening one of the most way to improve the mechanical properties of machine and structural parts. shot peening is a surface treatment process aimed to increasing material's fatigue strength by strain hardening an inducing favorable compressive residual stresses [1,2]. g. a. butz and j.o. lyst 1961[3], studied improvement in fatigue resistance of aluminum alloy 2014-t6 by shot peened and found the fatigue strength improvement is percentage by which stress for shot peened exceeds the residual stress all results improvement between (18-29%). j.e. locke et.al. 2005 [4], investigate of the fatigue crack growth of short crack embedded in the layer of residual stress that induced by shot peened for 7050-t7451 and 7075-t7351 aluminum alloys, the depth of the compressive residual stresses is less than 0.254mm and the depth of initial cracks smaller than 0.0254mm will be tested to determine the crack growth rates of the peened material. k.ch. seong et. al. 2005 [5], experimental results shows that (s.p) has superior effectiveness to increase the corrosion fatigue life of submerged in 3.5% nacl for different time of aa7075-t6. h.j. alalkawi et.al. 2010 [6], studied the effect of shot peening on the cumulated fatigue damage for 2024 aluminum alloy for round test specimen , the optimal time of shot peened found 10 minute to give the maximum compressive residual stresses. m. bendetti et. al. 2010 [7], investigate the effect of different shot peening treatments on the fatigue life for 7075t651 aluminum alloy, using rectangular cross section fatigue test specimens with two types of ahmed n. al-khazraji al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 111 (2017) 2 notches , filler radius 0.2 and 2 mm on each side of specimen. the fatigue improvement is more pronounced with increasing stress concentration. shot peening reduce the fatigue notch sensitivity factor about 20%. the maximum fatigue strength gain 79% for combined shot peening at notch radius 0.5 mm. m.wollmann et.al. 2011 [8], studied and comparing the notch sensitivity factor of various alloys before and after shot peening, one of this alloy is 2024 aluminum alloy. the higher work hardening capability or normalized high cycle fatigue strength, the lower notch sensitivity. the notch sensitivity were q=0.8 and 0.79 for 2024-t4and 2024-t6 aluminum alloys respectively. t.a. al-taie 2014 [2], investigate the effect of induced compressive residual stresses by (s.p.) at different time for aa6061-t651 and aa7075-t6, experimentally predicted the (o.p.t.) which was (10minute.) from insufficient different (s.p.ts) with 44.4% gain enhancement. n.a. hammied and saad a.h.2014 [9], used different (s.p.ts), were (5, 10, 15, 20 and 30min.) and its effect on mechanical properties of aa2024-t4, the results showed an increase in yield and tensile strength values up to (15 minute.) (s.p.t). the aim of this paper is to determine experimentally the optimum shot peening time of aa6061-t651 from sufficient different (s.p.ts), and then using rms to optimize by (anova) software to accurate the time. 2. experimental details 2.1. material and experimental procedures the al, mg, si aluminum alloy 6061-t651 is apperceptions hardening; it has good mechanical proportions and used in general purpose applications in civilian and military industries. a chemical analysis of this alloy is tested by spectra device, it summarized in table (1). table 1, chemical composition of 6061-t651 aluminum alloy. cu mg mn zn si fe cr ti al standard asm [10] 0.150.4 0.81.2 0.15 max. 0.25 max. 0.4-0.8 0.7 max. 0.040.35 0.15 max. bal. received 0.31 1.2 0.012 0.056 0.727 0.104 0.123 0.029 bal. according to astm-e8 [11], tensile test was down. the specimen geometry and dimensions shown in figure (1). high-cycle fatigue tests by used cantilever fatigue testing machine type gunt-wp140 as shown in figure (2). the fatigue conditions are pure reversed bending stress with zero mean stress. the geometry of the fatigue specimen [12] and his a circumferential notch radius 1.25mm made by using cnc machine to give perfect dimensions for all specimens. the specimens were classified into two groups, the first one without notch (smooth) and the second with notch radius 1.25mm as shown in figure (3). all groups are shot peened at the obtained optimal time 8min to induced the maximum surface compressive residual stresses by mechanical treatment. the degree of concentration is a factor in the fatigue strength of notched parts. the elastic stress concentration factor, �� as a ratio of the maximum stress ����, at the notch to the nominal stress �� �. the stress concentration factors for a homogenous isotropic material depend only on the geometry and mode of loading, figure (4), [13]. fig. 1. tensile test specimen (astm –e8) (all dimensions in mm). ahmed n. al-khazraji al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 111 (2017) 3 fig. 2. fatigue testing machine type gunt-hamburg wp140. (a) (b) fig. 3. the dimensions of fatigue test specimens (all dimensions in mm), (a) schematically smooth specimen. (b) schematically notch specimen. fig. 4. theoretical stress concentration factor kt for a round bar with a u notch subjected to bending [14]. the shot peening was accomplished by sintokagio centerfugal machine model stb-ob and by using the portable electrical additional device to ensure shot the specimens identical as shown in figure(5). in this machine, the motor rotates an impeller which bombards the shots towards the specimens at 1435 r.p.m motor rotational speed with one jet of shots at an average speed of 40 m/s. the material of the shooting balls is a low carbon steel with average diameter of 1.2 mm. ahmed n. al-khazraji al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 111 (2017) 4 fig. 5.the additional device put and fixed inside the rotary cylinder of the shot peening machine. the round shaft with shoulder fillet in bending, is extracted from applying the relation below [15]. � �. � …(1) where: � � ∗ � � � 2⁄ � ��� 64⁄ 3. result and discussion the tensile tests of the alloy are performed to obtain the value of the ultimate, yield tensile stresses before and after the shot peening. the results as shown in the table (2). there are a little increasing in the yield and ultimate tensile strength occurred due to shot peening effect ,which was (3.3%) and (2.5%) respectively. the x-ray diffraction (xrd) technique used to measurements the residual stresses on the surface of specimens after shot peened at optimal spt-8 minute to give the maximum residual stress is (-184.94mpa) with a (919%) enhancement compared with the metal as received (best shot penning) show the results of residual stresses at different s.p.t . it was observed from table (3) the optimum shot peening time was (8 minutes.). the surface roughness (��) was measured for three random selection specimens before and after shot peening and taken the average value micron) by using portable surface roughness device type pocket surf as shown in table (4). the s-n results that obtained from the fatigue tests for smooth (un-notch) specimens and notch at radius 1.25mm with depth 1mm specimens, after shot peened at optimal time 8 min. all tests were carried out at constant stress amplitude leading. the mean results of three specimens of each point of fatigue tests are in table (5), and plotted in the s-n curves as shown in figure (6). table 2, tensile tests results before and after optimum spt condition ��(mpa) ��(mpa) standard 310 276 received 320 300 optimum shot peened 8 min 328 310 table 3, experimental residual stresses at different (s.p.t.) s.p.t min. 0 4 6 8 10 20 residual stress [mpa] -18.14 -119 -155 -184.94 -154.19 -138.7 table 4, average surface roughness. ref. variation % surface roughness !"#$% shot peening time 0.43 as received present work 904 4.5 8 min. [2] 1144 5.1 10 min. ahmed n. al-khazraji al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 111 (2017) 5 table 5, final average s-n data for aa6061-t651 un-notch peened 8 min notch 1.25mm peened 8 min �& mpa nf cycle �& mpa nf cycle 230 26023 205 28200 200 85481 190 40513 190 132175 175 73567 180 201893 160 106293 170 317642 145 221782 160 521007 130 506193 150 798601 115 1017230 140 1556580 100 2394647 120 4462196 it is clear from table (4) that the roughness in present work was less than in ref [2], because the optimum shot peening (o.s.t) less than at ref [2]. fig. 6. smooth and notch radius 1.25 mm for 6061t651 aluminum alloy at different spts to comparing fatigue results with the other as in ref. [2] and plotted the results as shown in figure (7). fig. 7. smooth and notch radius 1.25 mm for 6061t651 aluminum alloy at different spts these curves give an indication about the variations in fatigue life. the fatigue life estimation equations were obtained. the consideration of endurance limit at *+ 10 . cycles, fitting curve with an accuracy 95%. the stress concentration factor (�+), notch sensitivity factor (q) and the gain in endurance limit put it in table ( 6 ). �& 821.3 ∗ * 12.34�. 146.859 mpa for (spt 8 min. un-notch). �& 1035 ∗ * 12.3784 114.747 mpa for (spt 8 min. notch). �+ :� �; +��<=>? @�a?�=�; b �c;?d +��<=>? @�a?�=�; = 3�..e78 33�.f�f 1.28 �� 1.62 from figure ( 4 ) g hi13 hj13 3.4e13 3..413 0.451 k�lm �&"mnopq �m� rssms�% t �&"mnopq �m� uspslvs�% �&"wxnoq �m� uspslvs�% t �&"mnopq �m� uspslvs�% ∗ 100% k�lm 114.747 t 95.222 129.94 t 95.222 ∗ 100% 56.24% k�lm 56.24 t 44.4 44.4 ∗ 100% 26.67% from the results of the fatigue tests, it can be observed that the value of the endurance limit at *+ 10 . cycles, given the highest value of compressive residual stress given at optimal time of shot peening (8 minutes for this alloy), the enhancement of the endurance limit gain is (56.24%) and the total enhancement percentage gain compering with ref. [2] is (26.67%), the comparison with others put it in table (7). ahmed n. al-khazraji al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 111 (2017) 6 table 6, values (z[ ,z] ,^% for specimens with 1 mm notch radius (6061-t651) shot peening time(min) smooth strength σ (mpa) notch strength σ (mpa) z[ z] q variation % q as received 129.940 95.222 1.36 1.62 0.58 received 8 146.858 114.747 1.28 1.62 0.451 -22.24 table 7, comparing gain results with references. alloy type spt min type of beads gain % ref. no. 7075-t651 6 ceramic 79 [7] 6061-t651 8 steel 56.24 present work 6061-t651 10 steel 44.4 [2] 4. modeling of fatigue life according to the experimental results of residual stresses induced for (un-notched& notched) specimens due to different (s.p.ts) and using response surface methodology(rsm) it has been selected the levels of input factors which shown in table (8). table (9) show the design matrix which was constructed to predict the optimum polynomials of fatigue life for the two cases (un-notched& notched) depending on two parameters (shot peening time& fatigue stress). it is clear from table.(9) a (13) tests were carried out according to (rsm) for each studied case(un notched & notched),and also observed for each s.p.t. the fatigue life obtained and level of fatigue stress. using analysis of variance (anova) a statistical program for the given data in design matrix, it was obtained the details of a significant parameters and values of the two obtained optimum polynomials which give the optimization of fatigue life (nf) for the two studied cases: table 8, used levels of input factors specimens type input factor levels 1 + 1 un-notch stress (mpa) 140 200 time (min) 6 10 notch (1.25mm) stress (mpa) 120 160 time (min) 6 10 ahmed n. al-khazraji al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 111 (2017) 7 table 9, design matrix for input factors and response (no. of cycle to failure) un-notch std. no. run no. stress (mpa) time (min) no. of cycle to failure 1 8 140 6 1.6e+006 2 9 200 6 50000 3 2 140 10 1.6e+006 4 13 200 10 70000 5 4 110 8 4e+006 6 6 230 8 900000 7 10 170 4 140000 8 11 170 12 150000 9 7 170 8 360000 10 5 170 8 370000 11 1 170 8 400000 12 3 170 8 390000 13 12 170 8 350000 notch 1 2 120 6 1.01723e+006 2 13 180 6 73567 3 6 120 10 1.01723e+006 4 9 180 10 50000 5 3 90 8 2.5e+006 6 12 210 8 600000 7 4 150 4 180000 8 1 150 12 100000 9 7 150 8 250000 10 11 150 8 235000 11 10 150 8 210000 12 5 150 8 245000 13 8 150 8 200000 for notch specimen *n. n_ p`pas on _�labus 1.05822c + 007 t 1.26048c + 005 ∗ wousww + 80144.01293 ∗ olxs + 367.27982 ∗ wousww4 t 5487.03987 ∗ olxs4 … "3% for un-notched specimens *n. n_ p`pas on _�labus 2.04862c + 007 t 2.21807c + 005 ∗ wousww + 2.31063c + 005 ∗ olxs t 576.5565 ∗ wousww4 t 14337.28448 ∗ olxs4 …(4) the predicted optimum shot peening times (o.s.t) according to (rsm)&(anova) are listed in table (10). table (8) show the results of significant values for the two cases according to anova software used. table 10, the optimum shot peening times for un-notched&notched specimens. stress(mpa) o.s.t(min.) nf(cycles) case 140.00 8.007 1664700 un-notched 120.00 7.538 1037950 notched ahmed n. al-khazraji al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 111 (2017) 8 table 11, anova for response surface reduced quadratic model for (no. of cycle to failure) un-notch source sum of squares df mean square f value p-value prob > f model 1.439e+013 4 3.598e+012 14429.97 < 0.0001 significant a-stress 7.177e+012 1 7.177e+012 28784.71 < 0.0001 b-time 1.333e+008 1 1.333e+008 0.53 0.4855 a² 6.170e+012 1 6.170e+012 24746.22 < 0.0001 b² 7.536e+010 1 7.536e+010 302.27 < 0.0001 residual 1.995e+009 8 2.493e+008 lack of fit 2.745e+008 4 6.864e+007 0.16 0.94 not significant pure error 1.720e+009 4 4.300e+008 cor total 1.439e+013 12 std. dev. 15789.79 mean 7.985e+005 c.v. % 1.98 press 3.901e+009 r-squared 0.9999 adj r-squared 0.9998 pred r-squared 0.9997 adeq precision 402.085 notch source sum of squares df mean square f value p-value prob > f model 5.559e+012 4 1.390e+012 4204.11 < 0.0001 significant a-stress 2.718e+012 1 2.718e+012 8222.39 < 0.0001 b-time 2.808e+009 1 2.808e+009 8.5 0.0194 a² 2.504e+012 1 2.504e+012 7574.32 < 0.0001 b² 1.104e+010 1 1.104e+010 33.39 0.0004 figure (8) is a three dimension surface curves constructed between fatigue lives as a response results depending on two significant parameters due rsm (shot peening time&fatigue stress). it is observed from table (10) & figure (8) that the optimum fatigue life was (1664700 cycles at predicted o.s.t 8.007min.&140mpa for unnotched specimens) and (1037950 cycles at predicted o.s.t. 7.538min.&120mpa fatigue stress) . the gain obtained of fatigue life due to this method for notched shot peened specimens compared with notched un peened specimens was (71.4%),calculated according to the following equation[2]: gain = (σl( notched&peened)) – σl (notched &unpeened))/((σl(smooth as received) –σl(notched &unpeened)) *100%. (a) un-notch specimen ahmed n. al-khazraji al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 111 (2017) 9 (b)notch specimen fig. 8. 3d surface plot showing the optimum input and output values. the value of σl (notched&unpeened taken 95.222mpa ref.[2]& smooth as received 129.94mpa. ,while the experimental gain in this work of fatigue life was (56.24%),that is mean a 27% enhancement in gain more using (rsm) compared with experiment and a 61% more than gain obtained by ref.[2]. table (12) explain the comparison between rsm results& experimental results of this work and references for shot peened notched specimens of aa6061-t651. table 12, comparing gain results with references (for peened notched ) specimens of aa6061-t651. alloy type excremental or theoretical spt min type of beads gain % ref. no. 6061-t651 exp. 8 steel 56.24 present work 6061-t651 exp. 10 steel 44.4 [2] 6061-t651 the. 7.30 71.4 present work 5. conclusions 1. the same optimum shot peening time, which was 8min. experimentally obtained for the two cases (un-notched& notched) specimens which gave a 56.24% gain for notched peened. 2. the optimum shot peening time for notched &peened specimens according to (rsm) was 7.538min. this gave a 71.4% gain in fatigue life compared with un-notched as received. 3. a 61% improvement by rsm method in fatigue life compared with ref. [2]. 4. a 26.6% improvement using rsm method in fatigue life compared with experimental results for this work 5. quadratic equations for two cases (notched& un-notched specimens) obtained using rsm &anova softwares to give the optimum fatigue life. 6. references [1] uros zupanc and janez grum, ''surface integrity of shot peened aluminum alloy 7075-t651'', journal of mechanical engineering, vol. 57, pp.379-384, 2010. [2] thamer a. al-taie , ''effect of compressive residual stresses on the notch sensitivity factor of different aluminum alloys'' thesis for the degree of master of science, university of technology, iraq, 2014. [3] g. a. butz and j. o. lyst,''improvement in fatigue resistance of aluminum alloys by surface cold working'', materials research and standards, usa, pp.951-956, 1961 [4] j. e. locke, b. kumar and l. salah, ''effect of shot peening on the fatigue endurance and fatigue crack growth rate of 7050 & 7075 aluminum alloys'', international conference on fracture, icf11, issue 5476, italy, 2005. [5] k.ch. seong, h.l. jae ''effects of shot peening on corrosion fatigue life of aa7075-t6''; nowon-gu, seoul korea 2005 [6] hussain j. al-alkawi, qusay k. mohammed and waleed s. al-nuami, ''the effect of shot peening and residual stresses on cumulative fatigue damage'', engineering and technology journal, vol. 28,issuo 15, pp.5055-5071, 2010. [7] m. benedetti, v. fontanari, c. santus and m. bandini, ''notch fatigue behavior of shot peened high strength aluminum alloys; experiments and predictions using a critical distance method'', international journal of fatigue, vol. 32, pp.1600-1611, 2010. [8] m. wollmann, j. atoura, m. mhaede, l. wagner,'' comparing fatigue notch ahmed n. al-khazraji al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 111 (2017) 10 sensitivity of various alloys before and after mechanical surface treating'', international conferences on shot peening (icsp-11), issue 71, usa, 2011. [9] nashwa abdul hammied , saad a.h.'' effect of shot peening time on mechanical properties of aluminum alloy 2024-t6; iraqi journal of mechanical & material engineering , volume 14; 2014 p(46-54) , babylon university. [10] american society for metals (asm), material data sheet for 6061 aluminum alloy, 1990. [11] american society for testing and materials (astm) e8/e8m-09, ''standard test methods for tension testing of metallic materials'', annual book of astm standards, edt 2010. [12] instruction manual wp-140 , fatigue testing apparatus p. 17, gunt hamburg , germany. [13] r. i. stephens, a. fatemi, r. r., stephens and h. o. fuchs, “metal fatigue in engineering”, 2nd ed., john wiley and sons, inc, 2001. [14] r. e. peterson, “stress concentration factor”, 2nd edition, john wiley & son, 1997. [15] m. a. meyers and k. k. chawla, “mechanical behavior of material”, prenticehall inc., usa, 1999. )2017( 1-11، صفحة 4د، العد13دجلة الخوارزمي الهندسية المجلم احمد نايف ابراهيم 11 t651-6061تاثير زمن السفع بالكرات المثالي على عمر الكالل لسبيكة االلمنيوم احمد نايف ابراهيم قسم الهندسة الميكانيكية /الجامعة التكنولوجية dr_ahmed53@yahoo.com :البريد االلكتروني الخالصة الذي يعطي افضل (o.s.t)تزداد طرديا مع وقت السفع. لكل معدن وقت مثالي للسفع ،االجهادات المتبقية الضغطية التي تتولد بطريقة السفع بالكرات . t651-6061عمر كالل في هذا البحث تم تحديد الوقت المثالي للسفع وباستخدام البرنامج االحصائي لسبيكة االلمنيوم وقbد تbم سbفع كbل مbن النbوعين باوقbات (1.25mm)تم تهيأة نوعين من العينات لفحص الكالل, النوع االول بدون حز , النوع الثاني بحbز نصbف قطbره .(184.94-)الذي اعطى اعلى اجهادات ضغطية متبقية (minutes 8)كان تحديد الوقت االمثل مختبريا حيثمختلفة للسفع. تم وذلك للحصول على امثل الخواص السطحية لعمر الكالل وذلك باختيار معbاملين همbا (وقbت السbفع rsm(منهجية استجابة السطح تم استخدام برنامج وجهادات الكالل). للعينbات المحbززة و (minutes 8.007)للتنبؤ بالوقbت األمثbل للسbفع. وكانbت النتbائج (anovaوقد تم استخدام البرنامج االحصائي (تحليل التباين (7.53minutes) ةbللعينات غير المحززة. تم الحصول على نموذجين رياضيين متعددة الحدود من الدرجة الثانية للحالتين التي تم دراستها وبمستوى وثوقي ٩٥%. فbي %61كانت نتيجbة التحسbن rsmواكن بعد استخدام برنامج [2]مقارنة بالمصدر %26.67عمليا تم الحصول على تحسين في عمر الكالل بنسبة . [2]عمر الكالل مقارنة مع المصدر <4d6963726f736f667420576f7264202d2032362d3431cde3cf20e6d3e3edd120e6cde3edcf20d4e3ceed> al-khwarizmi engineering journal,vol. 13, no. 1, p.p. improvement of dynamic buckling behavior of intermediate aluminized ahmed naif al-khazraji* hameed shamkhi al *,**department of mechanical engineering / university of technology/ baghdad ***department of machines and equipment / *** (received 20 https://doi.org/10.22153/kej.2017.08.003 abstract this paper experimentally investigated the dynamic buckling behavior of aisi 303 stainless steel aluminized and as received intermediate columns. twenty seven aluminizing at different aluminizing conditions of dipping temperature and dipping time (type 2), dynamic compression loading (compression and torsion), dynamic bending dynamic combined loading (compression, bending, and torsion) by using a rotating buckling test machine. the experimental results werecompared with tangent modulus theory, reduced modulus theory, and perry robertson interaction formula. reduced modulus was experimental results obtained showed an advantageous influence of hot buckling behavior of aisi 303 stainless steel intermediate columns. critical stress were19.4 % for intermediate columns type (2) compared with columns type (1) under dynamic compression loading, 8.7 % for intermediate columns type (2) compar loading, and 16.5 % for intermediate columns type (2) compared with columns type (1) under dynamic combined loading. keywords: dynamic buckling, hot-dip aluminizing, 1. introduction buckling may occur when there were compressive internal forces in the structure member. in fact, while tensile forces may only do work if the material deforms or rupture, for the case of compression there is a third possibility bucklingwhich consists of a lateral deflection of the material, in relation to direction of actuation of the compressive forces [1]. the phenomenon of buckling is not limited to columns. buckling can occur in beams, plates, shells, and other structural members under a variety of loading conditions [2, 3]. the buckling behavior of steel columns considers one of the important phenome khwarizmi engineering journal,vol. 13, no. 1, p.p. 2641 (2017) improvement of dynamic buckling behavior of intermediate aluminized stainless steel columns khazraji* samir ali al-rabii** hameed shamkhi al-khazaali *** department of mechanical engineering / university of technology/ baghdad department of machines and equipment / institute of technology / middle technical university / baghdad *email: dr_ahmed53@yahoo.com **email: alrabiee2002@yahoo.com ***email: hameedshamkhi@yahoo.com 20 october 2015; accepted 8 august 2016) https://doi.org/10.22153/kej.2017.08.003 investigated the dynamic buckling behavior of aisi 303 stainless steel aluminized and as twenty seven specimens without aluminizing (type 1) and 75 specimens with hot aluminizing at different aluminizing conditions of dipping temperature and dipping time (type 2), dynamic compression loading (compression and torsion), dynamic bending loading (bending and torsion), and under dynamic combined loading (compression, bending, and torsion) by using a rotating buckling test machine. the compared with tangent modulus theory, reduced modulus theory, and perry robertson was formulated to circular cross-section for the specimens of type (1).the experimental results obtained showed an advantageous influence of hot-dip aluminizing treatment on the dynamic ainless steel intermediate columns. the improvements based on the average value of 19.4 % for intermediate columns type (2) compared with columns type (1) under dynamic compression loading, 8.7 % for intermediate columns type (2) compared with columns type (1) under dynamic bending loading, and 16.5 % for intermediate columns type (2) compared with columns type (1) under dynamic combined dip aluminizing, intermediate columns, aisi 303 stainless steel. buckling may occur when there were compressive internal forces in the structure tensile forces may only do work if the material deforms or rupture, for the case of compression there is a third possibility which consists of a lateral deflection of the material, in relation to direction of actuation of [1]. the phenomenon of buckling is not limited to columns. buckling can occur in beams, plates, shells, and other structural members under a variety of loading conditions [2, 3]. the buckling behavior of steel columns phenomenon that had been studied and analyzed a series of experimentally tests are carried on cold formed austenitic stainless steel square, rectangular, and circular hollow section members to examine the buckling behavior of columns and beams under effect of gradually increased single and combined loads (compression, bending, and compression-bending) with two types of ends conditions pin-ends and fixed buckling of solid and hollow ck35 and ck45 alloy steel columns under combined dy loading has been studied experimentally and the obtained results showed that the failure resistance of the columns depends on the type of cross section and initial deflection of column [ al-khwarizmi engineering journal improvement of dynamic buckling behavior of intermediate ** department of mechanical engineering / university of technology/ baghdad technology / middle technical university / baghdad investigated the dynamic buckling behavior of aisi 303 stainless steel aluminized and as specimens without aluminizing (type 1) and 75 specimens with hot-dip aluminizing at different aluminizing conditions of dipping temperature and dipping time (type 2), were tested under loading (bending and torsion), and under dynamic combined loading (compression, bending, and torsion) by using a rotating buckling test machine. the compared with tangent modulus theory, reduced modulus theory, and perry robertson section for the specimens of type (1).the dip aluminizing treatment on the dynamic the improvements based on the average value of 19.4 % for intermediate columns type (2) compared with columns type (1) under dynamic ed with columns type (1) under dynamic bending loading, and 16.5 % for intermediate columns type (2) compared with columns type (1) under dynamic combined from a long time. a series of experimentally tests are carried on cold formed austenitic stainless steel square, rectangular, and circular hollow section members to examine the buckling behavior of columns and nder effect of gradually increased single and combined loads (compression, bending, and bending) with two types of ends ends and fixed-ends [4]. the buckling of solid and hollow ck35 and ck45 alloy steel columns under combined dynamic loading has been studied experimentally and the obtained results showed that the failure resistance of the columns depends on the type of crosssection and initial deflection of column [5]. the ahmed naif al-khazraji al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 2641(2017) 27 nitride case hardening (liquid nitriding) surface treatment is used to enhance the buckling resistance of square columns with different length, material (ck45, ck67, ck101), and constant cross section (10 ×10) mm subjected to the effect of single and combined dynamic loads [6]. the surface treatment by shot peening is used to enhance the buckling resistance of a series of (ck35) steel column with solid circular crosssection under single and combined dynamic loads by increasing the yield and ultimate strength of columns material [7]. above the elastic limit of a material, the modulus of elasticity becomes a function of the stress. in other word, one should know the operating level of the stress before one can find out the modulus. this makes the analysis in the inelastic region complicated [8]. in case of columns with intermediate slenderness, i.e., columns which are stable for stresses higher than the proportionality limit, the failure of intermediate columns occurs subsequent to the onset of inelastic behavior [9]. euler’s theory may still be used, provided that the local modulus of elasticity corresponding to the critical stress is used [10]. this leads to develop the so-called tangent modulus theory and reduced modulus theory to describe the buckling behavior of intermediate columns and to predict its buckling load. this paper examines the effect of hot-dip aluminizing process (hda) on the dynamic buckling behavior of intermediate columns subjected to dynamic compression loading (compression and torsion), dynamic bending loading (bending and torsion, and dynamic combined loading (compression, bending, and torsion), of stainless steel (aisi 303) material by series of circular cross-section columns, of different slenderness ratio, with and without hda surface treatment at different dipping temperatures (���) and dipping times (���). 2. considered theories 2.1 tangent-modulus theory in 1889, f. engesser, a german engineer, suggested that if column failure occurred at a stress above the proportional of the material, the column strength could be obtained by simply replacing young’s modulus, �, in euler’s buckling formula by the tangent modulus, �� , [3, 11]. which �� is the local slope of the stress-strain curve in the inelastic range, i.e., the slope of the stress-strain curve at the stress = �� � [12]. the elastic modulus is the �� (tangent modulus) if the stress is above the elastic limit of the column’s material but � (young’s modulus) if the stress is below the elastic limit [13]. the tangent modulus is given by [3, 11]: �� = ���� …(1) the critical or engesser stress may be expressed by means of modification of euler formula in which �� replaces � : � = ���� = ��������� … �2� from the experimental tensile test results, the stress-strain curve for aisi 303 stainless steel used in this research can be represented by the following relationship: = 2 ∗ 10"#$ − 4 ∗ 10'#� + 286278 #− 31.594 … �3� where �#� and � � are the uniaxial strain and stress, respectively. the tangent modulus is given by eq. (1): �� = 0 0# so, by differentiation of eq. (3) with respect to #, one can write: �� = 0 0# = 6 ∗ 10"#� − 8 ∗ 10'#+ 286278 … �4� now, substituting eqs. (3) and (4) into eq.(2) gives 2 ∗ 10"#$ − 4 ∗ 10'#� + 286278 # − 31.594 =12�34�2 ∗ 56 ∗ 10"#� − 8 ∗ 10'# + 2862786 … �5� by rearranging eq. (5), one can write: 2 ∗ 10"#$ − 74 ∗ 10' + 6 ∗ 10" ∗ 12�34�28 #� +7286278 + 8 ∗ 10' ∗ 12 �34�28 # − 731.594 + 286278 ∗ 12 �34�28 = 0 … �6� equation (6) can be solved to determine the correct value (root) of real strain # and then substitute this value in eq. (4) to determine the value of the tangent modulus �� [14]. 2.2 reduced modulus theory (double modulus theory) the second modification on euler’s equation was done by f. engesser in 1895, by replacing � (young’s modulus) by �9 (reduced modulus) or �� (double modulus) which lies between the elastic modulus and tangent modulus. this suggestion led to the reduced theory or double ahmed naif al-khazraji al modulus theory [8, 15]. the derivation of the general equation of �9 is found in refs. and this equation is given by the form: �9 = � :;:< + �� :�:< where the variables in eq. (7) may be defined, with referring to fig. (1), that represent a column of arbitrary cross-section subjected to an axial load � which gradually increases. further, the column remains perfectly straight till the critical load ��� is reached. at this load, the column bends slightly and the reduced modulus theory predicted that the critical stress �� is given by: 9 = ���� = ���9����� fig. 1. determination of reduced elastic modulus [8]. 2.2.1 reduced modulus for circular cross section for the present paper requirements, the value of :; and :� must be formulated for circular cross section in order to determine the value of consider a column with circular cross shown in fig. (2). referring to eq. (7) :; = = �> ;���?@ 0� using polar coordinates system, one can write:> = a sin e ∴ �ghijklmm no lplqlk�,0> = a cos e 0e ulkv�g no lplqlk�, w = a inm�xly no lplqlk�, 0� = 2w0> z> m[\m�h�[�hkv �]. �c) and (d) into eq. (e), one can write: ∴ 0� = 2a��cos e�� 0e now, limits of integration must be changed to polar form as follow: at > = l →sin_; �9 and at > = a → e = 1� al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 28 the derivation of the is found in refs. [8, 13] … �7� where the variables in eq. (7) may be defined, , that represent a column section subjected to an axial which gradually increases. further, the column remains perfectly straight till the critical is reached. at this load, the column bends slightly and the reduced modulus theory predicted … �8� determination of reduced elastic modulus circular for the present paper requirements, the value must be formulated for circular crosssection in order to determine the value of �9 . consider a column with circular cross-section, as …�y� one can write: … �\� … �i� inm e … �0� … �l� c) and (d) into eq. (e), one … �o� now, limits of integration must be changed to → e = e` = and >; = > − l = �a sin e − l by substituting >; and 0� form eqs. (g) and (f), respectively , in eq. (a) , it can be written: :; = 2a� = �a sin e − l�� �cosa2bc and :< = : + �l� = 1 9de + �a� where, :< = :; + :� or :� by substituting :< and :; from eqs. (h) and (9) respectively, one can write: :� = 71 9de + �a�l�8 − 2a� =a2bcl�� �cos e�� 0� by substituting :; and :� from eqs. (9) and (10), respectively with the values of � computed the value of �9 of the column from eq. (7). fig. 2. geometrical dimensions of a column with circular cross-section used in formula of reduced modulus. 2.3 perry robertson interaction formula it is important to evaluate the buckling strength of real columns, presence of initial mechanical and geometrical imperfections, a perry robertson interaction formula [16, 17, and 18] is adopted as follows: � = f g where, f = 1 h + ih� − ����j@.k l 1 in which, h = 0.5 m1 + nm� − �`o + ���� � = 341 . p�q r where the value of the imperfection factor ( and the limiting non-dimensional slenderness ratio khwarizmi engineering journal, vol. 13, no. 1, p.p. 2641(2017) � … �v� form eqs. (g) and (f), respectively , in eq. (a) , it can be written: �cos e�� 0� … �9� �l� … �g� � = :< − :; from eqs. (h) and (9) �a sin e −a2bc … �10� from eqs. (9) and (10), � and ��, it can be of the column from eq. geometrical dimensions of a column with section used in formula of reduced perry robertson interaction formula it is important to evaluate the compressive buckling strength of real columns, ��, in the presence of initial mechanical and geometrical imperfections, a perry robertson interaction ] is adopted as follows: … �11� … �12� o �o … �13� … �14� imperfection factor (n) dimensional slenderness ratio ahmed naif al-khazraji al (�`) are obtained from ref. [9]8. the value of the effective slenderness ratio (��) is calculated by using the relation [20]: �� = st� = t4� the value of slenderness ratio under which column’s type is intermediate is obtained using the following relation [15]: �� = �� = �.u � vw and by substituting the value of e, vw (2), and the value of k=0.7 (for fixed ends) in eq. (16), one finds that the value of critical slenderness ratio is �� = 86.5. 3. experimental work 3.1. material used and buckling test machine aisi 303 stainless steel intermediate columns of circular cross-section, ø=8 mm, of different slenderness ratio, with and without hot aluminizing were tested by using a rotating column buckling test machine capable to apply dynamic compression loading, dynamic bending loading, and compression-bending dynamic loading, with column ends support of fixed pinned and rotating speed of 17 and 34 r.p.m. in this research, low speed (17 r.p.m) was used in all dynamic buckling experiments. the photographs of the rotating buckling test machine, with some of the devices and parts of it, are shown in fig. (3). more details of buckling test machine, used in this research, are in ref. [5]. the detail of the chemical composition of stainless steel is shown in table (1), and the significant mechanical properties are given in table (2). while experiments of hot dip aluminizing aisi 303 stainless steel rods were carried out by using a self-construction system of hotdip aluminizing [18]. a high purity aluminum (99%) was dipping bath, and the hda process variables were dipping temperature and dipping time temperature of the molten aluminum bath was controlled to be within x5 y by using the temperature control system shown in fig. more details of the hda system and the temperature control system, used in this research, are in ref. [18]. al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 29 . the value of the ) is calculated by … (15) the value of slenderness ratio under which column’s type is intermediate is obtained using … �16� from table (2), and the value of k=0.7 (for fixed-pinned ends) in eq. (16), one finds that the value of material used and buckling test aisi 303 stainless steel intermediate columns section, ø=8 mm, of different slenderness ratio, with and without hot-dip aluminizing were tested by using a rotating column buckling test machine capable to apply dynamic bending bending dynamic loading, with column ends support of fixed pinned and rotating speed of 17 and 34 r.p.m. in this research, low speed (17 r.p.m) was used in all dynamic buckling experiments. the photographs rotating buckling test machine, with some of the devices and parts of it, are shown in fig. more details of buckling test machine, used in the detail of the chemical composition of stainless steel is shown in table (1), and the significant mechanical properties are given in table (2). while the experiments of hot dip aluminizing aisi 303 stainless steel rods were carried out by using a dip aluminizing . a high purity aluminum (99%) was used for dipping bath, and the hda process variables were dipping temperature and dipping time. the temperature of the molten aluminum bath was y using the temperature control system shown in fig. (4). more details of the hda system and the temperature control system, used in this research, 3.2. specimens types there are two types of buckling specimens used in this work, these two types are: type (1) as received specimens (non intermediate columns with circular cross section z = 8 qq, : = 201.1 and different lengths. table (3) gives the geometrical dimensions and buckling parameters of these specimens. fig. 3. the rotating buckling test machine used in the present research [18]. khwarizmi engineering journal, vol. 13, no. 1, p.p. 2641(2017) there are two types of buckling specimens types are: as received specimens (non-aluminized): intermediate columns with circular cross-1 qqe, x = 2 qq, and different lengths. table (3) gives the geometrical dimensions and buckling parameters the rotating buckling test machine used in ahmed naif al-khazraji al table 1, chemical compositions (wt. %) of aisi 303 stainless steel alloy c si used material a 0.114 0.539 standard (asm) [17] up to 0.15 up to 1.0 a: source: state company for inspection and engineering rehabilitation (sier)/baghdad. table 2, experimental mechanical properties of aisi 303 stainless steel used in present work specimens). aisi 303 st. st. {|}~ (mpa) {� ∗ (mpa) 880 673 * proof stress at 0.2% of stain. ** in gauge length u` = 25 qq. fig. 4. temperature control system used to control the temperature of the molten aluminum [18]. type (2) aluminized specimens: intermediate hot dip aluminized (hda) columns with circular cross-section. these specimens have a constant length l=200 mm, but at different hot conditions from dipping temperature (700, 740, al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 30 chemical compositions (wt. %) of aisi 303 stainless steel. si mn p cr 0.539 1.14 0.032 18.20 up to 1.0 up to 2.0 up to 0.2 17-19 source: state company for inspection and engineering rehabilitation (sier)/baghdad. properties of aisi 303 stainless steel used in present work (average of three ∗ (mpa) e (gpa) elong.** % { (mpa) 204.2 41.4 269 used to control the temperature of the molten aluminum [18]. aluminized specimens: intermediate hotdip aluminized (hda) columns with circular section. these specimens have a constant length l=200 mm, but at different hot-dip conditions from dipping temperature (700, 740, 780, 820, and 860 y) and different dipping times (1, 2, 3, 4, and 5 minutes). table (4) gives the parameters of hot-dip and buckling of these specimens. it should be noted that the thickness of the aluminum layer, to be formed during the hda process, is in the micrometer. so, hda process in changing of the cross sectional area of aluminized column it can be neglected in calculations the values of critical buckling stresses. 3.3. failure criterion of buckling when the maximum deflection of the column reaches the critical value of deflection ( column length, then the load measured (by pressure gauge) is the critical buckling load of the column. in the present work, the value of the critical deflection of the column is taken was (����qq� = �u ∗ 1%� + �`) [6 because of the rotating effect on the reading of the column deflection using a dial gauge, a laser cell circuit tool was fabricated, with whistle sound, fixed on electronic vernier (with a reading accuracy of 0.01 mm), fig. ( reading of critical deflection (��� khwarizmi engineering journal, vol. 13, no. 1, p.p. 2641(2017) ni 8.19 8-10 (average of three {�} (mpa) 269.2 and different dipping times (1, 2, 3, 4, and 5 minutes). table (4) gives the dip and buckling of these specimens. it should be noted that the thickness of the aluminum layer, to be formed during the hda process, is in the micrometer. so, the effect of the hda process in changing of the cross sectional area of aluminized column it can be neglected in calculations the values of critical buckling failure criterion of buckling when the maximum deflection of the column e critical value of deflection (���) of the column length, then the load measured (by pressure gauge) is the critical buckling load of the column. in the present work, the value of the critical deflection of the column is taken was 6, 16, and 18]. because of the rotating effect on the reading of the column deflection using a dial gauge, a laser cell circuit tool was fabricated, with whistle sound, fixed on electronic vernier (with a reading accuracy of 0.01 mm), fig. (5), to make the ��) more strict. ahmed naif al-khazraji al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 2641(2017) 31 table 3, geometrical dimensions and buckling parameters of specimens type (1) * u� = �u ; � = 0.7 for fixed-pinned supports; ** ����qq� = �u ∗ 1%� + �`; *** compression load= (compressiontorsion) load; bending load= (bending-torsion) load. bending load at mid span; combined load= (compressionbending-torsion load). bending load at mid span); **** �� = �.p r��� = 86.5 , ho �� < �� → hk�lxql0hy� inp[qk. no. symbol � (mm) �� * (mm) �� (mm) ��� ** (mm) �� �= ��� � type of *** loading type **** of column 1 1a 160 112 0.55/2 1.88 56 compression intermediate 1b 0.2/2 1.7 bending 1c 0.9/2 2.05 combined 2 2a 170 119 0.6/2 2 59.5 compression intermediate 2b 0.25/2 1.83 bending 2c 1.1/2 2.25 combined 3 3a 180 126 0.71/2 2.16 63 compression intermediate 3b 0.85/2 2.23 bending 3c 1.35/2 2.48 combined 4 4a 190 133 0.96/2 2.38 66.5 compression intermediate 4b 0.5/2 2.15 bending 4c 1.3/2 2.55 combined 5 5a 200 140 0.8/2 2.4 70 compression intermediate 5b 0.25/2 2.13 bending 5c 1.3/2 2.65 combined 6 6a 210 147 1.22/2 2.71 73.5 compression intermediate 6b 0.34/2 2.27 bending 6c 1.46/2 2.83 combined 7 7a 220 154 1.1/2 2.75 77 compression intermediate 7b 0.72/2 2.56 bending 7c 1.65/2 3.03 combined 8 8a 230 161 1.21/2 2.91 80.5 compressio n intermediate 8b 0.7/2 2.65 bending 8c 1.6/2 3.1 combined 9 9a 240 168 1.2/2 3 84 compressio n intermediate 9b 0.82/2 2.81 bending 9c 1.7/2 3.25 combined ahmed naif al-khazraji al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 2641(2017) 32 table 4, geometrical dimensions and buckling parameters of the hot-dip aluminized columns type 2 (intermediate columns) no. dipping temperature ��� �y� dipping time ~�� (min) � (mm) �� (mm) �� (mm) ��� (mm) �� type of column type of loading a1 1 700 1 200 140 0.75/2 2.43 70 intermediate compression 2 2 0.74/2 2.3 3 3 1.2/2 2.38 4 4 0.85/2 2.37 5 5 0.6/2 2.45 b1 6 740 1 200 140 0.75/2 2.38 70 intermediate compression 7 2 0.74/2 2.26 8 3 0.9/2 2.28 9 4 0.75/2 2.45 10 5 0.43/2 2.34 11 780 1 200 140 0.55/2 2.35 70 intermediate compression c1 12 2 0.9/2 2.13 13 3 0.68/2 2.36 14 4 0.7/2 2.5 15 5 0.25/2 2.49 d1 16 820 1 200 140 0.72/2 2.35 70 intermediate compression 17 2 1/2 2.45 18 3 0.98/2 2.3 19 4 0.7/2 2.6 20 5 0.9/2 2.45 e1 21 860 1 200 140 0.6/2 2.55 70 intermediate compression 22 2 1.2/2 2.46 23 3 0.9/2 2.43 24 4 1.1/2 2.3 25 5 0.92/2 2.38 a2 26 700 1 200 140 0.75/2 2.38 70 intermediate bending 27 2 0.7/2 2.35 28 3 0.6/2 2.3 29 4 0.55/2 2.28 30 5 0.7/2 2.35 b2 31 740 1 200 140 0.6/2 2.3 70 intermediate bending 32 2 0.6/2 2.3 33 3 0.4/2 2.2 34 4 0.48/2 2.24 35 5 0.5/2 2.25 c2 36 780 1 200 140 0.67/2 2.34 70 intermediate bending 37 2 0.35/2 2.18 38 3 1/2 2.5 39 4 0.9/2 2.45 40 5 0.65/2 2.33 d2 41 820 1 200 140 0.9/2 2.45 70 intermediate bending 42 2 0.6/2 2.3 43 3 0.8/2 2.4 ahmed naif al-khazraji al 44 4 45 5 e2 46 860 1 47 2 48 3 49 4 50 5 a3 51 700 1 52 2 53 3 54 4 55 5 b3 56 740 1 57 2 58 3 59 4 60 5 c3 61 780 1 62 2 63 3 64 4 65 5 d3 66 820 1 67 2 68 3 69 4 70 5 e3 71 860 1 72 2 73 3 74 4 75 5 fig. 5. system used to control the deflection of columns during buckling test. table 4 (continue) al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 33 1.2/2 2.6 0.98/2 2.49 200 140 1/2 2.5 70 intermediate 0.85/2 2.43 0.8/2 2.4 0.98/2 2.49 0.25/2 2.13 200 140 1.14/2 2.57 70 intermediate 1.15/2 2.58 1/2 2.5 0.95/2 2.48 0.7/2 2.35 200 140 1.12/2 2.56 70 intermediate 0.9/2 2.45 1.12/2 2.56 0.9/2 2.45 0.62/2 2.31 200 140 1.2/2 2.6 70 intermediate 0.5/2 2.25 1.2/2 2.6 0.7/2 2.35 0.45/2 2.23 200 140 0.84/2 2.42 70 intermediate 0.6/2 2.3 0.5/2 2.25 1.12/2 2.56 0.82/2 2.41 200 140 1.2/2 2.6 70 intermediate 0.95/2 2.48 0.5/2 2.25 0.5/2 2.25 1.42/2 2.71 system used to control the deflection of columns during buckling test. khwarizmi engineering journal, vol. 13, no. 1, p.p. 2641(2017) intermediate bending intermediate combined intermediate combined intermediate combined intermediate combined intermediate combined system used to control the deflection of columns during buckling test. ahmed naif al-khazraji al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 2641(2017) 34 4. results and discussion table (5) shows the experimental results of dynamic buckling test of 303 aisi column specimens without aluminizing (type 1). in this table, it can be observed that the critical buckling load (���v) decreased with increasing in effective slenderness ratio (��) for both dynamic compression load (compression-torsion load) and dynamic combined load (compression-bendingtorsion load). also, it can be seen that the bending stress ( ��<.) is greater than the critical buckling stress for all slenderness ratios, but is also decreased with increased ��. in order to make a comparison between the experimental results and theoretical results, tangent modulus theory, reduced modulus theory and perry-robertson interaction formula are used to calculate the theoretical critical buckling stress for the specimens of type (1), and the results are shown in table (6). from table (5) and table (6), it can be observed that the experimental critical stress ( ��v) is, in general, lower than the value of theoretical critical stress ( � , 9 , yk0 �) from tangent modulus theory, reduced modulus theory, and perry robertson interaction formula, respectively. the difference between the experimental and theoretical results is due to in both tangent modules and reduced modulus theories, the column is assumed as a perfect column (no initial imperfection) and the applied load is gradually increased with no dynamic effect (torsion load) and with no lateral load (bending load). in perry-robertson formula, effect of the initial imperfection is considered, but the dynamic effect of loading is not considered. in general, it can be observed that the results obtained by using perry-robertson formula are more accurate compared with results obtained using tangent modulus theory and reduced modulus theory. table (7) shows the experimental results of dynamic buckling test of specimens type 2 (hotdip aluminized intermediate columns) with constant slenderness ratio of �� = 70 and different hot-dip conditions (dipping temperature and dipping time). from table (7), it can be detected that there is enhancement in buckling resistance of intermediate aluminized columns under dynamic compression load (compression and torsion), dynamic bending load (bending and torsion), and dynamic combined load (compression, bending, and torsion). in order to show the improvement of dynamic buckling resistance of aluminized columns (type 2) compared with non-aluminized columns (type 1), fig. (6) and fig. (7) are plotted by using the experimental results of table (5) for specimens type (1), and table (7) for specimens type (2), whereas table (6) gives the theoretical results from tangent modulus theory, reduced modulus theory, and perry robertson interaction formula. the improvement of buckling resistance, based on the average value of experimental critical buckling stress ( ��v), is as follow: (19.4 %) for intermediate columns type (2) compared with columns type (1), under dynamic compression loading, and (8.7 %) for intermediate columns type (2), compared with columns type (1) under dynamic bending loading, and (16.5 %) for intermediate columns type (2) compared with columns type (1) under dynamic combined loading. these enhancement ratios of buckling resistance are illustrated in fig. (8). it should be noted that the effect of rotating of the column (torsional loading) during the applied of compression load and/or compression-bending loads was appeared clearly first by a spatial (nonplanar) shape of column deformation until buckling is occur and second by reducing the value of the critical buckling load. the lateral loading (bending load) on the rotating columns leads to a fast increasing in the lateral deflection of the column under combined loading conditions and a signification reduction in the axial compressive load and as a result, it decreases the buckling resistance of the columns compared with the case without lateral loading . it is experimentally noted that the effect of the lateral loading on the buckling resistance was much greater than the effect of the twisting or torsional loading for the same slenderness ratios. under dynamic compression loading, fig. (9), the buckling resistance of hda columns (type 2) is decreased with the increase in dipping time (���) for hot-dip conditions of 740 y, 780 y, and 860 y, but the buckling resistance is increased with the increase in dipping time for hot-dip conditions of 700 y, and 820 y with maximum value of increasing at 700 y. under dynamic bending load, fig. (10), the bending resistance of hda columns is approximately remained constant with increasing in dipping time. under dynamic combined load, fig. (11), the buckling resistance is generally increased with the increase in dipping time from 1 minute to approximately 4 minutes and then decreased for all dipping temperatures except the dipping temperature 740 y , where the buckling resistance decreased with the increase in ahmed naif al-khazraji al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 2641(2017) 35 dipping time from 1 minute to 3 minutes and then increased with dipping time. the bending resistance of hda columns, fig. (11), under dynamic combined loading is decreased with the increase in dipping time at 700 y, 780 y, and 860 y, but it is increased with the increase in dipping time at 740 y, and 820 y. from the above discussion, it can be noticed that the hda conditions of dipping time 3 minutes and dipping temperature of 700 y and/ or 820 y give maximum buckling resistance under both dynamic compression load and dynamic combined load. 5. conclusions 1. the experimental values of the critical buckling stress ( ��v) for non-aluminized intermediate columns, (�� < ��, ���56 �n 84�, are less than the theoretical values of critical buckling stress ( � , 9 , yk0 �) predicted by tangent modulus theory, reduced modulus theory, and perry robertson interaction formula, respectively. the average decreasing in percentage for values of the experimental critical buckling stress under dynamic compression load compared with the theoretical values of critical buckling stress are: -51.015 %. (tangent modulus theory), 50.44 % (reduced modulus theory), and 29.143 % (perry-robertson formula). 2. using of hotdip aluminizing surface treatment has made two benefits, one of them is to develop a protection layer for the substrate material from the environment conditions, and the other is the improvement of dynamic buckling resistance of intermediate aluminized columns under dynamic compression loading, dynamic bending loading, and under dynamic combined loading. 3. the improvement in the dynamic buckling resistance was (19.4 %) for intermediate columns type (2) compared with columns type (1) under dynamic compression loading, (8.7%) for intermediate columns type (2) compared with columns type (1) under dynamic bending loading, and (16.5%) for intermediate columns type (2) compared with columns type (1) under dynamic combined loading. 4. the optimum hot-dip aluminizing conditions, that give a maximum enhancement of dynamic buckling resistance for the specimens of type (2), are: dipping time of (t��=3 to 4 min) and dipping temperature of (t��=700y and 820y). 5. the effect of the torsional loading during the application of compression load, bending load, and compression-bending loads was appeared clearly first by a spatial (non-planar) shape of column deformation until buckling is occurred and second by effecting on the value of the critical buckling load. while, the lateral loading (bending load) on the rotating columns leads to a fast increasing in the lateral deflection of the column under combined loading conditions and a signification reduction in the axial compressive load (critical buckling load). 6. the average decreasing in percentage for values of the experimental critical buckling load under dynamic combined load (for as received specimens and hda specimens), is 49.6% compared with values of the experimental critical buckling load without lateral bending load (under dynamic compression load) for the same effective slenderness ratios. ahmed naif al-khazraji al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 2641(2017) 36 table 5, experimental results of dynamic buckling test of column specimen’s type (1) table 6, theoretical values of critical buckling stress using tangent modulus theory, reduced modulus theory, and perryrobertson formula for specimens of type (1). no. symbol type of loading ���� ��� {��� ����� ����. ��� {���. ����� 1 1a comp. 16257.742 323.4375 ---- 1b ben. ----530.4 263.79936 1c comb. 7775.442 154.688 489.6 243.507 2 2a comp. 14844.025 295.3125 ---- 2b ben. ----510 269.50655 2c comb. 7068.583 140.625 469.2 247.946 3 3a comp. 13783.738 274.2188 ---- 3b ben. ----489.6 273.94549 3c comb. 6361.725 126.563 448.8 251.117 4 4a comp. 12370.021 246.0938 ---- 4b ben. ----469.2 277.11615 4c comb. 6008.296 119.531 428.4 253.019 5 5a comp. 10956.304 217.9688 ---- 5b ben. ----448.8 279.01855 5c comb. 5654.867 112.5 408 253.653 6 6a comp. 10249.446 203.9063 ---- 6b ben. ----428.4 279.65268 6c comb. 5301.434 105.469 387.6 253.019 7 7a comp. 9542.5877 189.8438 ---- 7b ben. ----408 279.01855 7c comb. 4948.008 98.438 367.2 251.117 8 8a comp. 9189.1585 182.8125 ---- 8b ben. ----387.6 277.11615 8c comb. 4806.637 95.625 346.8 247.946 9 9a comp. 8482.3002 168.75 ---- 9b ben. ----367.2 273.94549 9c comb. 4665.265 92.813 326.4 243.507 no. � (mm) �� (mm) �� �= ��� � ��� � ��)  ~ �¡��� {� �����  ¢ �¡��� {¢ ����� {� ����� 1 160 112 56 1.88 137.131 431.578 139.343 438.539 391.878 2 170 119 59.5 2 146.248 407.714 147.706 411.779 365.339 3 180 126 63 2.16 154.764 384.847 155.667 387.093 340.049 4 190 133 66.5 2.38 162.686 363.084 163.1 364.008 316.270 5 200 140 70 2.4 170.035 342.485 170.335 343.089 294.137 6 210 147 73.5 2.71 176.836 323.069 176.934 323.248 273.684 7 220 154 77 2.75 183.123 304.832 183.189 304.942 254.878 8 230 161 80.5 2.905 188.928 287.743 188.956 287.785 237.640 9 240 168 84 3 194.288 271.761 194.3 271.777 221.866 ahmed naif al-khazraji al table 7, experimental results of dynamic buckling test of no. ���� ��� {��� ����� a1 1 13430.309 267.188 a2 2 12723.450 253.125 3 15550.884 309.375 4 12016.592 239.063 5 14844.025 295.313 b1 6 14137.167 281.25 b2 7 14844.025 295.313 8 12723.450 253.125 9 10602.875 210.938 10 14137.167 281.25 c1 11 14137.167 281.25 c2 12 12723.450 253.125 13 13430.309 267.188 14 12723.450 253.125 15 12016.592 239.063 d1 16 12723.450 253.125 d2 17 12723.450 253.125 18 12723.450 253.125 19 14137.167 281.25 20 14137.167 281.25 e1 21 13076.879 260.156 e2 22 14137.167 281.25 23 9189.159 182.813 24 12016.592 239.063 25 12016.592 239.063 fig. 6. critical stressslenderness ratio relation for stainless steel 303 aisi columns (type 1) dynamic compression, and dynamic combined loads compared with theoretical results. al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 37 results of dynamic buckling test of the hot-dip aluminized columns type 2 (intermediate columns) no. ����. ��� {���. ����� no. ���� ��� {��� ����� 26 448.8 279.018 a3 51 22950 456.576 27 693.6 431.210 52 28687.5 570.719 28 448.8 279.018 53 48768.75 970.223 29 448.8 279.018 54 25818.75 513.648 30 448.8 279.018 55 45900 913.151 31 448.8 279.018 b3 56 25818.75 513.648 32 408 253.653 57 17212.5 342.432 33 489.6 304.384 58 14343.75 285.359 34 489.6 304.384 59 20081.25 399.504 35 489.6 304.384 60 43031.25 856.079 36 530.4 329.749 c3 61 17212.5 342.432 37 448.8 279.018 62 22950 456.575 38 448.8 279.018 63 25818.75 513.648 39 612 380.479 64 25818.75 513.648 40 367.2 228.287 65 20081.25 399.504 41 489.6 304.384 d3 66 22950 456.576 42 489.6 304.384 67 22950 456.576 43 530.4 329.749 68 22950 456.576 44 489.6 304.384 69 28687.5 570.719 45 448.8 279.018 70 25818.75 513.648 46 530.4 329.749 e3 71 28687.5 570.719 47 469.2 291.701 72 22950 456.576 48 489.6 304.384 73 28687.5 570.719 49 469.2 291.701 74 31556.25 627.792 50 571.2 355.114 75 28687.5 570.719 slenderness ratio relation for (type 1) under combined loads fig. 7. bending stressslenderness ratio relation for stainless steel 303 aisi columns dynamic bending loading. khwarizmi engineering journal, vol. 13, no. 1, p.p. 2641(2017) dip aluminized columns type 2 (intermediate columns). � ����. ��� {���. ����� 456.576 530.4 329.749 570.719 510 317.066 970.223 489.6 304.384 513.648 408 253.653 913.151 367.2 228.287 513.648 408 253.653 342.432 489.6 304.384 285.359 469.2 291.701 399.504 448.8 279.018 856.079 489.6 304.384 342.432 571.2 355.114 456.575 489.6 304.384 513.648 469.2 291.701 513.648 367.2 228.287 399.504 346.8 215.605 456.576 408 253.653 456.576 448.8 279.018 456.576 408 253.653 570.719 408 253.653 513.648 408 253.653 570.719 428.4 266.335 456.576 428.4 266.335 570.719 408 253.653 627.792 346.8 215.605 570.719 448.8 279.018 slenderness ratio relation for stainless steel 303 aisi columns (type 1) under ahmed naif al-khazraji al fig. 10. critical buckling stressdipping time relation for hda loading. fig. 11. critical stressdipping time relation for hda columns (type 2) under dynamic combined loading fig. 8. critical stress for the specimens of type (1) and type (2) at the same effective slenderness ratio al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 38 dipping time relation for hda columns (type 2) under dynamic bending dipping time relation for hda columns (type 2) under dynamic combined loading critical stress for the specimens of type (1) and type (2) at the same effective slenderness ratio. fig. 9. critical buckling stress relation for hda aluminized under dynamic compression load khwarizmi engineering journal, vol. 13, no. 1, p.p. 2641(2017) columns (type 2) under dynamic bending dipping time relation for hda columns (type 2) under dynamic combined loading. stressdipping time hda aluminized columns (type 2) under dynamic compression loading. ahmed naif al-khazraji al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 2641(2017) 39 notation ££¤ the cross-sectional area of the column ¥ ¦§¨ modulus of elasticity � ¦§¨ reduced modulus �9 ¦§¨tangent modulus �� ££ critical deflection of the column at a critical buckling condition= ��� l © experimental bending load ª��<. ££« moment of inertia of the column cross sectional area about z-axis : ££« moment of inertia of the area �; that lies above the neutral axis n-n :; ££« moment of inertia of the area �� that lies below the neutral axis n-n :� ££« moment of inertia of the column cross sectional area about neutral axis n-n :< dimen sionless effective-length factor = 0.7 for fixed-pinned ends support � mm unsupported and effective length of the column u, u� n (newto n) theoretical and experimental critical buckling load p­®p̄ °± ££ smallest radius of gyration of the column x y dipping temperature ��� s (sec.) dipping time ��� greek letters ²§¨ the uniaxial stress { ²§¨ experimental bending stress ��<. ²§¨ experimental critical buckling stress ��v ²§¨ theoretical critical buckling stress (perryrobertson formula) � ²§¨ theoretical critical buckling stress (reduced modulus theory) 9 ²§¨ critical buckling stress (tangent modulus theory) � ²§¨ ultimate and proportional limit of column’s material stress ³w�, vw ²§¨ the yield strength g ££ initial and critical deflection of the column �` , ��� dimens ion-less the limiting and nondimensional slenderness ratio �`, � dimen sionless effective and critical slenderness ratio �� , �� dimen sionless the reduction factor accounting for buckling f dimen sionnless the imperfection factor (perry-robertson formula n dimen sionless the uniaxial strain # 6. references [1] t. h. g. megson,”structural and stress analysis”, butterworth-heinemann, 2000. [2] analysis theories, tutorials and examples”, taylor & francis, 2008. [3] r. c. hibbeler, si conversion by s. c. fan,” statics and mechanics of materials”, prentice-hall, inc., 2004. [4] l. gardner and d. a. nethercot, “experiments on stainless steel hollow sections-part 2: member behaviour of coloumns and beams”, journal of constructional steel research, vol. 60, p.p. 1319-1332, (2004). [5] kifah hameed al-jubori, “columns lateral buckling under combined dynamic loading”, phd. thesis, university of technology, department of technical education, 2005. [6] hamed ali hussein,”buckling of square columns under cycling loads for nitriding steel din (ck45, ck67, ck101)”, phd. thesis, university of technology, department of mechanical engineering, 2010. [7] al-alkhawi h. j. m., al-khazraji a. n., and essam zuhier fadhel, “determination the optimum shot peening time for improving the buckling behavior of medium carbon steel”, eng. & tech. journal, vol. 32, part (a), no. 3, 2014. ahmed naif al-khazraji al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 2641(2017) 40 [8] sung-ha hwang, jin-hwa song, and yongsuk kim, “effects of carbon content of carbon steel on its dissolution into a molten aluminum alloy”, materials science and engineering a 390, pp. 437–443, 2005. [9] hishamuddin hj. husain, muhamad daud, anasyida abu seman and abdul razak daud, “preliminary study on metallic coating of steel substrates through hot dip aluminizing by using energy dispersive xray spectroscopy (edx) technique”, journal of nuclear and related technologies, vol. 6, no. 2,pp. 63-69, december, 2009. [10] rajab mohammed hussein, “improvement of stainless steel (316l) hot corrosion and oxidation resistance by aluminizingsiliconizing”, phd. thesis, university of technology, department of production engineering and metalluragy, 2007. [11] g. h. awan, f. ahmed, l. ali, m. s. shuja, and f. hasan, “effect of coating thickness on the formability of hot dip aluminized steel”, pak. j. engg. & appl. sci., vol. 2, p.p. 14-21, jan 2008. [12] n. r. baddoo and b. a. burgan, “structural design of stainless steel”, the steel construction institute, sci publication p291 2001, 2001. [13] euro inox and the steel construction institute, “structural design of stainless steel”, 3rd edition, 2006. [14] l. gardner and d. a. nethercot, “designers’ guide to en 1993-1-1. eurocode 3: design of steel structures. general rules and rules for building”, the steel construction institute, thomas telford ltd., 2005. [15] james m. gere, “mechanics of materials”, 6th ed, thomson learning, inc., 2004. [16] zdeněk p. bažant and luigi cipolin”stability of structures elastic, inelastic, fracture, and damage theories”, dover puplications, inc., 2003. [17] asm handbook,”surface engineering”, asm international, vol. 5, 1994. [18] hameed shamkhi jaber,” the influence of hot-dip aluminizing on buckling behavior of columns”, phd. thesis, university of technology, department of mechanical engineering, 2015. ا���ر�� �� �� 1، ا�� د13 ��� ا���ارزم� ا��� ��� ا����ما���� ،41-26 )2017( 41 ��م�-� ,+� ة ا�%�( ا��)�وم ��% أ ا��#���� ��"��!� ا�!�ل 4�2�3 ���ك ا0�/��ج ا� ** ���6 +�� ا����56 *�� ا���ر��ا�� ���7 ��65 ا���+�� ���*** ��� ا������ ا���������� * /������ ا�"�! � ا���� ��� ا������ ا���������� ** / ������ ا�"�! � ا���� ���ا���! �� / ��� ا����&% وا�� �ات *** ���� /'(�� ,+�اد -ا�"�! � ا��(��� ا� dr_ahmed53@yahoo.com : ا��0.1 ا/���.و�-* alrabiee2002@yahoo.com : ا� ر�د ا����رو��** hameedshamkhi@yahoo.com : ا/���.و�ا��0.1*** ا��8�� ��)� ا�)�ل ا������c و�d. ا������c !% ا�@b4 ا��(�وم �4@�أ �<=��ة;� :ھ8ا ا�761 ا��6(5 ا� �4��4�ك ا/�1 �ج ا����0!���!aisi 303 . .�f�; g6; ھ8ه ا/=��ة g@6: 7�i ،-��!��0ا/�1 �ج ا�� k�i٢٧ ����c! .�d ���= )type 1 ( ٧٥و %oا�+�. ا��� �)0.(, ����c! ���= )type 2( ، k�i ا�q+�ط زا&� (و,z.وف u! .�d��x4 !% در�� i.ارة ا�+�. وز!% ا�+�.، ,�v��uام !�s6: ��t ا/�1 �ج ا��وار و�k�i ���6 ا/�q+�ط ا����0!�� ;� !(�ر�� ا����&^ ![ ). k�i ا�q+�ط زا&� k�i ا���6ء وk�i ا���اء(ا�k�6 ا��.bt و�8t\ ) k�i ا���6ء زا&� k�i ا���اء(وا/���6ء ا����0!��) k�i ا���اء �0.z�tangent modulus theory �0.zو�reduced modulus theory �+�_وperry robertson interaction formula . %! %���ض ا�.+� �0.z� ام�u�ا�reduced modulus theory _�uق ا�@�+� ا��)�b0"�د :(� ;� اv, �reduced modulus ة ا� ���4 . ��4()[ ا��ا&.ي�&�x&^ ا���أظ�.ت ا�� 4' �4�ك ا/�1 �ج ;�fv; g6. ا/��iل ا����0!����= %o6((� !% =���4 ا/���� ,��+�. ا������6% !(�و!� ا/�1 �ج ا����0!��. ا���ا/0"�,, .�fv�ھ8ا ا� ke�; ��g ا/���د ا�6.ج، وھ8ه ا���f� b=��ة !���)� ا�)�ل ا�����u!� :ھ8��� �0�h! b��, 761ا/;-ا ا� ��f=��ة !���)� ) % 19.4( :=4' و:5 ا��6 !(�ر�� ,�/=��ة )f�)type 2=��ة !���)� ا�)�ل ) %8.7(و;�fv; g6. ا��k��6 ا/�q+�طا����0!��-، و ) type 1(!(�ر�� ,�/=��ة ) type 2(ا�)�ل )type 1 (k�i .�fv; g6;ا/���6ء ا����0!��و و)ل) % 16.5�و;�fv; g6. ا��k��6 ا��type 1 ( -��!��0(!(�ر�� ,�/=��ة ) f� )type 2=��ة !���)� ا�) bt.ا�� . 42 1-introduction: al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 8, no. 2, pp 1229 (2012) an experimental study on the effect of shape and location of vortex generators ahead of a heat exchanger wisam abed kattea department of machines and equipment engineering /university of technology email: wisam_bd@yahoo.com (received 15 september 2011; accepted 30 january 2012) abstract an experimental study is carried out on the effect of vortex generators (circular and square) on the flow and heat transfer at variable locations at (x = 0.5, 1.5, 2.5 cm) ahead of a heat exchanger with reynolds number ranging from 62000< re < 125000 and heat flux from 3000 ≤ q ≤ 8000 w/m2 . in the experimental investigation, an apparatus is set up to measure the velocity and temperatures around the heat exchanger. the results show that there is an effect for using vortex generators on heat transfer. also, heat transfer depends on the shape and location. the circular is found to be the best shape for enhancing heat transfer at location [xm=0.5 cm] distance before heat exchanger is the best location for enhancing heat transfer. the square is the best shape for enhancing heat transfer at location [xm=2.5 cm] distance before heat exchanger is the best location for enhancing heat transfer. the results of flow over heat exchanger with vortex generators are compared with the flow over heat exchanger without vortex generators. heat transfer around heat exchanger is enhanced (56%, 50%, 36%) at location (x=0.5, 1.5, 2.5cm) respectively by using circular vortex generators without turbulator and heat transfer around heat exchanger is enhanced (39%, 42%, 51%) at location (x=0.5, 1.5, 2.5cm) respectively by using square shape vortex generators without turbulator. keywords: vortex generator: vgs, nux: local nusselt number heat exchanger, vortex flow, heat transfer. 1. introduction convectional types of heat exchanger are externally plain tube in cross flow. they are widely used in chemical, petrochemical, automotive industry, cooling towers, heated pipes refrigerators of power plants as well as in applications for heating, refrigeration and air conditioning. in finned tube heat exchanger liquid or steam flows through the tube and gas through fin ducts, [1], [2]. heat transfer is closely related to fluid dynamics. that is why heat transfer is considered simultaneously with fluid dynamics [3]. heat transfer and fluid dynamic around curvilinear body as cylinder is complex process and need a big efforts to find out temperatures, pressure and velocity distribution. therefore one must know what happens when the fluid flows over bluff bodies as sphere, wire and tube. the ability to manipulate a flow field to improve efficiency or performance is of immense technological importance. flow control is one of the leading areas of research of many scientists and engineers in fluid mechanics. the potential benefits of flow control include performance and maneuverability, affordability, increased range and payload, and environmental compliance. the intent of flow control may be to delay/advance transition, to suppress / enhance turbulence, or to prevent/promote separation. the resulting benefits include drag reduction, lift enhancement, mixing augmentation, heat transfer enhancement, and flow–induced noise suppression. the objectives of mailto:wisam_bd@yahoo.com wisam abed kattea al-khwarizmi engineering journal, vol. 8, no.2, pp 12 -29 (2012) 13 flow control may be interrelated, leading to potential conflicts as the achievement of one particular goal may adversely affect another goal. for example, consider an aircraft wing for which the performance is measured by the improvement in lift-to-drag ratio. promoting transition will lead to a turbulent boundary layer that is more resistant to separation and increased lift can be obtained at higher angle of incidence. the viscous or skin – friction drag for a laminar boundary layer can be an order of magnitude smaller than that for a turbulent boundary layer. however, a laminar boundary layer is more prone to separation resulting in a loss in lift and an increase in form drag. the performance of liquid-to-air and twophase-to-air heat exchangers is important in many applications, including thermal management and processing systems found in the air conditioning, automotive, refrigeration, chemical, and petroleum industries. improving the performance of these heat exchangers can lead to a smaller surface-area requirement, reduced material cost, and a lower heat exchanger mass. furthermore, improving heat exchanger performance can have a significant impact on the environment through improvements in energy efficiency. the total thermal resistance in these heat exchangers can be considered as the sum of three contributions: the liquid or two-phase convective resistance, the wall conductive resistance, and the air-side convective resistance. the air-side convective resistance is typically the dominant resistance to heat transfer,[4], and efforts to improve these heat exchangers should focus on the air side heat-transfer behavior. the type of turbulator using heat exchanger is shown in figure (1). [5] fig. 1.type of vortex generator. 1.1. vortex generation at the front of region of tube there is high heat transfer due to small boundary layer (b.l) thickness but there is a small heat transfer at the rear region especially at separation point. this region is therefore prime focus area for transport enhancement, [4]. the strategy proposed here involves placing the vortex generators (v.gs) in front of or behind the tube to prevent growth of boundary layer (b.l) and to transfer the separation point to the rear region of tube in order to reject the minimum heat transfer region to the rear. the (v.gs) are small plates placed in the stream flow of mixed flow, disturbing flow and controlling the growth of boundary layer, [6], has any shape; the common shapes of (v.gs) (winglets) are circular and square. the (v.gs) winglets affect both tube and fin, all previous studies were studied the effect of wing and winglet on heat transfer from the fin by generating a vortex due to pressure difference between front surface and back surface, this vortex will mix the hot fluid near the surfaces with cold main flow, this process enhances heat transition from the surfaces, [7]. the effect of winglet on tube guides the flow at high momentum in to low heat transfer region, [6].the size, shape and angle of attack of winglet determine the specific characteristics of the vortices generated in the flow, [8]. 1. 2. application of vgs the advantages of these vortex generators or tabulators (turbulence promoters) are to: 1. improve heat exchange in compact heat exchangers and electronic equipment packages or microelectronic devices in industrial application ,[9] like the wide use of plate-fin and fin-tube heat exchangers, for example, in dry cooling towers, in chemical industry and in automotive applications ,[10]. 2. enhance heat transfer in channels. e.g, parallel plate channel, rectangular, triangular, square ducts, u-bend of strong curvature applications, and grooved channel, [11]. 3. increase heat transfer rate inside or out side tubes, for example, gas flow out side the tube and liquid flow inside the tube and the finned tubes situated in vertical channel. 4. enhance the cooling capability of gas-cooled nuclear rector, for example, finned nuclear fuel. d e l t a w i n g rec tan gul ar win g d el ta w i n g le t rec tan gul ar win glet wisam abed kattea al-khwarizmi engineering journal, vol. 8, no.2, pp 12 -29 (2012) 14 5. increase internal cooling in the passages of modern gas turbine blades and vanes that must be protected from hot gas streams. 6. improve the aerodynamic performance by using various types of vortex generators, for example, to improve the performance of conical diffusers, or by using thin slender wings to make modern combat airplanes fly at high angles of attack. 7. decrease vortex losses in channels, for example, in channels of power plants, ventilation systems, and in various pipes, owing to the influence of the positive pressure gradient associated with variation in cross section or bending of the channel intense formation of vortices which takes place as a rule due to flow separation. these formations of vortices cause an increase in hydraulic losses and in degree of no uniformity. a new method of decreasing losses is based on division of vortices by transverse baffles or fins positioned on one side [12]. 8. in aerodynamics, in spite of longitudinal (stream wise) vortices, which lead to an improvement of 80%, also a reduction of 5% behind the investigated grids depends on the wavelength and the intensity of the disturbance [13]. 1.3. applications of heat exchangers flow of this nature can be found in engineering systems of significant technological interest such as heat exchangers, nuclear reactor cores, aircooled solar collectors, some microelectronic circuit boards, waste water aeration tanks as well as chemical mixers and other chemical engineering applications [14]. 1.4. objective of present work problem the experimental goals of this study are to: 1-investigate the flow and heat transfer phenomena of multi-types vortex generators located in rectangular ducts and to enhance heat transfer in turbulent flows. 2-set up an experiment model for a duct rig especially designed and manufactured for this study to cover wide range of applications with more accurate tools of measurements for flow pattern and temperature isothermal contours in air and solid domains. 3-investigate the effect of changing reynolds number, velocity, temperature, and thermal performance, and average nusselt number on ducts and vgs surfaces. 2. literature survey 2.1. the effect of vortex on heat exchanger chien-nan lin and jiin-yuh jang [15] studied the use of fins with embedded wave-type vortex generators to enhance heat transfer in fin-tube heat exchangers .an infrared thermo vision is used to visualize the temperature distribution on the surface of a scaled-up plain fin and upon fins with embedded vortex generators. numerical methods are used to investigate the conjugate heat transfer and to perform a 3-d turbulence. analysis of the heat transfer and fluid flow associated with wave type vortex generators embedded fins. the current results indicate that heat transfer and friction losses are strongly dependent on the geometric parameters of the vortex generators. this study identifies maximum improvement of (120) % in the local heat transfer coefficient and an improvement of (18.5) % in the average heat transfer coefficient. furthermore; it is found that a reduction in fin area of approximately (18–20) % may be obtained if vortex generators embedded fins are used in place of plain fins. finally, it is noted that the magnitude of the attainable fin area reduction increases for higher reynolds numbers. pesteei, et al [16] measured local heat transfer coefficients on fin-tube heat exchanger with winglets using a single heater of 2 inch diameter and five different positions of winglet type vortex generators. the measurements were made at reynolds number about 2250. flow losses were determined by measuring the static pressure drop in the system. results showed a substantial increase in the heat transfer with winglet type vortex generators. it was observed that average nusselt number increased by about (46) % while the local heat transfer coefficient was improved by several times as compared to plain fin-tube heat exchanger. the maximum improvement is observed in the re-circulation zone. the best location of the winglets was with dx = 0.5d and dy = 0.5d. the increase in pressure drop for the existing situation was of the order of (18) %. torii, et al [17], in their paper propose that can augment heat transfer but nevertheless can reduce pressure-loss in a fin-tube heat exchanger with wisam abed kattea al-khwarizmi engineering journal, vol. 8, no.2, pp 12 -29 (2012) 15 circular tubes in a relatively low reynolds number flow, by deploying delta winglet-type vortex generators. the winglets are placed with a heretofore-unused orientation for the purpose of augmentation of heat transfer. this orientation is called „„common flow up‟‟ configuration. the proposed configuration causes significant separation delay, reduces form drag, and removes the zone of poor heat transfer from the near-wake of the tubes. this enhancement strategy has been successfully verified by experiments in the proposed configuration. in case of staggered tube banks, the heat transfer was augmented by (30) % to (10) %, and yet the pressure loss was reduced by (55) % to (34) % for the reynolds number (based on two times channel height) ranging from 350 to 2100, when the present winglets were added. in case of in-line tube banks, these were found to be (20%) to (10%) augmentation, and (15%) to (8%) reduction, respectively. in a joardar and jacobi [18] the effectiveness of delta-wing type vortex generators was experimentally evaluated by full-scale windtunnel testing of a compact heat exchanger typical to those used in automotive systems. the mechanisms important to vortex enhancement methods are discussed, and a basis for selecting a delta-wing design as a vortex generator is established. the heat transfer and pressure drop performance are assessed at full scale under both dryand wet-surface conditions for a louveredfin baseline and for a vortex-enhanced louvered-fin heat exchanger. an average heat transfer increase over the baseline case of (21) % for dry conditions and (23.4) % for wet conditions was achieved with a pressure drop penalty smaller than (7) %. vortex generation is proven to provide an improved thermal-hydraulic performance in compact heat exchangers for automotive systems. 2.2. wing and winglet–type vortex generators heat transfer and fluid mechanics data were obtained by pauley and eaton [19], for a turbulent boundary layer with arrays of embedded stream wise vortices containing both counter-rotating and co-rotating vortex pairs. the data show that these arrays can cause both large local variations in the heat transfer rate and significant net heat transfer augmentation over large areas. close proximity of other vortices strongly affects the development of the vortex arrays by modifying the trajectory that they follow. the vortices in turn produce strong distortion of the normal two-dimensional boundary layer structure, which is due to their secondary flow. when one vortex convects another toward the wall, a strong boundary layer distortion occurs. the heat transfer is elevated where the secondary flow is directed toward the wall and reduced where the secondary flow is directed away from the wall. when adjacent vortices lift their neighbor away from the wall, minimal modification of the heat transfer results . the primary influence of grouping multiple vortex pairs into arrays is the development of stable patterns of vortices. these stable vortex patterns produce vortices that interact with the boundary layer and strongly modify the heat transfer far downstream, even where the vortices have decayed in strength. vortex generators are small plats placed in the flow path (sohal et al)[7] , using to generate a secondary flow or vortices by swirl and disability the flow, along the side edges of vortex generator the flow was separated and it generated a longitudinal vortices due to pressure difference between the forward and back side of vortex generators. vortex generators such as pins, ribs, wings, winglets have been successfully used as a powerful way for enhanced heat transfer in the development of modern heat exchangers. vortex generators can be generating a transfer longitudinal vortex with strongly disturbed the flow structure. longitudinal vortex generated by using wing and winglet and spiral the flow around there axis. many researchers have studied the effect of vortex generator on heat transfer and pressure drop from the duct wall numerically and experimentally with common type of vortex generated (rectangular and triangular (delta) shapes). the analogy between heat and mass transfer has been used by wang et al, [20], to obtain local and average heat transfer characteristics over a complete flat tube-fin element with four vgs per tube. several types of surfaces involved in heat transfer process such as fin surface mounted with vgs, its back surface (mounted without vgs) and flat tube surface are considered. the mass transfer experiments are performed using naphthalene sublimation method. the effects of the fin spacing and vgs parameters such as height and attack angle on heat transfer and pressure drop are investigated. the comparisons of heat transfer enhancement with flat tube-fin element without vgs enhancement under three constraints are carried out. the local nusselt number distribution reveals that vgs can efficiently enhance the heat transfer in the region near flat tube on fin surface wisam abed kattea al-khwarizmi engineering journal, vol. 8, no.2, pp 12 -29 (2012) 16 mounted with vgs. on its back surface the enhancement is almost the same as on the fin surface mounted with vgs but enhanced region is away from flat tube wall with some distance. average results reveal that increasing of vgs height and attack angle increases the enhancement of heat transfer and pressure drop, whereas small fin spacing causes greater increase in pressure drop. the heat transfer performance, correlations of nusselt number and friction factor are also given. tiggelbeck et al, [21], investigated the effect of four types of vortex generators (delta wing, delta winglet rectangular wing and rectangular winglet) as shown in figure (2) on local heat transfer and drag of plat fins and compared the results between these types of vortex generators and in the reynolds number range (2000-9000) with angle of attack range of (30°-90°). the results show that the vortex generators increase heat transfer and also the flow losses in channel, and for all vortex generators geometries there exists an optimum angle of attack between (50 ° and 70 °) for maximum heat transfer. however the flow losses increase monotonically with the angle of attack. results show that the winglet gives better performance than wings and pair of delta winglet performs slightly better than the pair of rectangular winglets. fig. 2. triangle and rectangle wings and winglets. 2.3. vortex phenomenon davis and moore [22], presented numerical solutions for two-dimensional time-dependent flow about rectangles in infinite domains . the numerical method utilizes a third order upwind differencing for convection and a leith type of temporal differencing. an attempted use of a lower-order scheme and its inadequacies are also described. the reynolds-number regime investigated is from 100 to 2,800. other parameters that are varied are upstream velocity profile, angle of attack, and rectangle dimensions. the initiation and subsequent development of the vortex-shedding phenomenon was investigated. passive marker particles provide an exceptional visualization of the evolution of the vortices both during and after they are shed. the properties of these vortices are found to be strongly dependent on reynolds number, as are lift, drag, and strouhal number. computed strouhal numbers were compared well with those obtained from a wind-tunnel test for reynolds numbers below (1,000). yasuo mori et al, [23], studied experimentally the mechanism of symmetrical vortex shedding behind a cylinder in a uniform, upward flow by heating the wake with fine wires or by using a splitter plate or mesh. in the case of heating the wake the vortices are gradually modified from karman vortex to symmetrical vortices with increase of heat input. similar symmetrical vortex shedding is also observed by the increase of the splitter plate length or mesh number behind the cylinder. an experimental investigation of a longitudinal vortex/boundary layer system was made by eibeck and eaton [24], to understand the effects of the vortex on local convective heat transfer coefficients. measurements in the presence of a single longitudinal vortex embedded in an otherwise two-dimensional turbulent boundary layer included local stanton number distributions, momentum and thermal boundary layer profiles, and skin friction distributions. the local stanton number varied, with an increase of (22) % over flat plate values in the downwash region of the vortex, and decreases of (12) % in the up wash region. the vortex imposed spanwise variations of boundary layer parameters such as thickness, wall shear, and profile shape. in spite of this, the heat transfer process was locally dominated by twodimensional mechanisms, as evidenced by the existence of a log-region in the boundary layer, as well as the applicability of the reynolds analogy. a b c d g f α h β j k l m o p n e wisam abed kattea al-khwarizmi engineering journal, vol. 8, no.2, pp 12 -29 (2012) 17 the heat transfer effects on an isolated longitudinal vortex embedded in a turbulent boundary layer were examined experimentally by eibeck and eaton [25], for vortex circulations ranging from (0.12 to 0.86). the test facility consisted of a two-dimensional boundary-layer wind tunnel, with a vortex introduced into the flow by a half-delta wing protruding from the surface. in all cases, the vortex size was of the same order as the boundary-layer thickness. heat transfer measurements were made using a constant-heat-flux surface with 160 embedded thermocouples to provide high resolution of the surface-temperature distribution. threecomponent meanvelocity measurements were made using a four-hole pressure probe. span wise profiles of the stanton number showed local increases as large as 24 percent and decreases of approximately 14 percent. the perturbation to the stanton number was persistent to the end of the test section, a length of over 100 initial boundarylayer thicknesses. the weakest vortices examined showed smaller heat transfer effects, but the stanton number profiles were nearly identical for the three cases with circulation greater than γ/u∞δ99= 0.53. the local increase in the stanton number is attributed to a thinning of the boundary layer on the downwash side of the vortex. experimental studies on bodies of revolution at high angles of attack have shown that the forces and moments developed are greatly affected by the formation of rolled up vortex cores. thus it is felt that an accurate model of the vortex would aid in the design of fuselage fore bodies or slender bodies in general. due to geometric simplicity several mathematical models of the vortex flow over a slender, sharp-edged, delta wing have been formulated. however, these models generally ignore the entrainment effect of the vortex core, and are found to yield results which are not in agreement with experiment, thus, their extension to the more general case would be of little value. a technique referred to as the leading-edge suction analogy, has been found to yield extremely accurate results when compared with experiment. paul [26], indented to propose a mathematical model of the vortex, which incorporates the previously ignored entrainment effect, and leads to an expression similar to the leading-edge suction analogy. 2.4. scope of the present study the aim of present study is to investigate turbulent flows in rectangular ducts using twoshapes of vgs and different locations and dimensions, to know the effect of these small bodies on flow and heat transfer characteristics. experimental investigations are to be undertaken in the present study. in the experimental part, none of the previous studies have tackled the problem of constant wall temperature along the duct. therefore, a rig is to be built to study the velocities and temperatures for a range of reynolds number (62000-125000) so that the flow become fully development, using accurate tools and modern measurement equipments and devices that can be calibrated accurately. also we found correlation between the average nusselt number and reynolds number (62000125000) in different vortex generator shapes (circular, square). thus, the layout of research can be demonstrated as follows: 1. set up an experimental rig to measure the velocity, temperatures. 2. study the effect of vorticities on the heat transfer on the heat exchanger. 3. study the obstruction that can produce maximum heat transfer. 2.5. summary a conclusion of the available data in literatures for effect of vortex generators on heat exchanger, both wing and winglet – type vortex generators and vortex phenomena was presented. all data related to study friction factor, pressure drop, heat transfer from heat exchanger, and relation between nusselt number and reynolds number. from this summary and to the author ‟ s knowledge no study of the heat transfer and pressure drop through the heat exchanger by using vortex generators, circular and square shapes was conducted. 18 fig. 3. scheme diagram. 3. experimental work 3.1. rig requirement a schematic diagram given in figure (3) shows the experimental arrangement. the experiment was carried out at the heat transfer laboratories of the university of technology using plain tube heat exchanger with six rows tube staggered and vortex generator. the test model was constructed from rectangular wood duct the dimensions of duct were 0.3m height and 0.15m width and 3m length, and the length of duct before the heat exchanger is 0.3 m. 3.2. rig description and preparation the test rig shown in figure (4) is designed and manufactured to fulfill the requirements of the test system for finned duct. the experimental apparatus consists basically of: 4 1 2 5 6 7 8 9 10 1thermometer calibrator 6electrical heater 2-digital thermometer 7-plian tube heat exchanger 3-thermocouples 8-rectangular duct 4digital anemometer 9-throttling valve 5fan 10vortex generators 11flow meter 9 5 11 3 wisam abed kattea al-khwarizmi engineering journal, vol. 8, no.2, pp 12 -29 (2012) 19 1-the airflow rates supply section. 2-the test section. (heat exchanger). 3-the heating and control sections. 4-the measuring instruments. 5-vortex generators. most of these parts are designed and manufactured during the current work, and care was taken to prevent any air leakage between the connected parts; the rig was completely damaged and during the current work so it was rehabilitated reconstructed according to the acceptable wind tunnel standards. fig. 4 rig description. 3.3. air supply equipment suction type axial fan shown in figure (5) was used to supply the flow of air to the rig working section. the axial fan [made by tecquipment in england, se. no. w/4/20029,] is driven by a.c. motor, the flow of air is controlled by using an adjustable throttling valve mounted just at the mouth of the air intake. since there is no need for any connection in the fan inlet and the throttling valve being fully open to obtain maximum air flow rate , the air delivered by the fan should has a uniform velocity profile with minimum turbulence level. fig. 5. axial fan. 3.4. air duct it consist of a rectangular wood duct as shown in figure (5) which is constructed of four section clipped tightly together. identical entry and exist section are separated by a plain center section which can easily be replaced with the optional heat exchanger .the apparatus is supplied with the axial fan connected to the exit . the fan discharges directly to the atmosphere thought an adjustable throttle plate which can be used to vary the volume flow rate. air flow rate measurement is computed by using a pitot static tube and manometer or anemometer, the dimensions of duct were 0.3m height and 0.15m width and 3m length. 3.5. plain tube heat exchanger a bank of pure copper heat transfer tube arranged vertically consists of 33 tube 5/8 inch outer diameter and 1/2 inch inner diameter tube 30 cm length as shown in figure (6) . hot water supply and return duct connection are made by means of flexible rubber hoses and plug in connection through heat exchanger. water temperature is measured by thermocouples. wisam abed kattea al-khwarizmi engineering journal, vol. 8, no.2, pp 12 -29 (2012) 20 fig. 6. plain tube heat exchanger. 3.6. vortex generators the vortex generator was used to generate the longitude vorticities to make difference in pressure between front surface of heat exchanger flow and the end surface causes enhanced heat transfer from heat exchanger. most studies used two common shapes of winglets, (circular and square) shapes as shown in figure (7a&7b) . in the experimental the following things were fixed: there were two types of grid vortex generator 1one grid consisting of (21) pieces of small circular, diameter=2.5 cm. the area of small piece of circular is (4.84) cm 2 . 2the other consisting of (21) pieces of small square, length=2.2cm. the area of small piece of square is (4.84) cm 2 . the purpose of this study is to compare the enhancement heat transfer with vortex generator and without vortex generator. fig. 7.a circular vortex generator. fig. 7.b square vortex generator. wisam abed kattea al-khwarizmi engineering journal, vol. 8, no.2, pp 12 -29 (2012) 21 3.7. water pump water pump of [q=60 l/min]capacity and a (20) m head is used to circulate hot water between heat exchanger and water heater by using flexible pipes as shown in figure (8). fig. 8. water pump and heater. 3.8. supply unit of hot water water tank of (150) liter capacity provided with two heaters each of (3) kw capacity, a thermostat is used to control water temperature at 60 ْ c as shown in figure (8). 3.9. the measuring instruments 3.9.1. digital thermometer this digital thermometer contains pt 100 ohm thermometer and thermocouple type k/j/r/e/t thermometer. it contains also microcomputer circuit with high performance wide temperature measuring range. it is used to measure temperature. see figure (4). 3.9.2. digital anemometer this vane-type probe portable anemometer provides fast accurate readings, with digital readability and the convenience of a remote sensor separately. it is used to measure the average air velocity. the low friction ball bearing design allows free vane movement, resulting in accuracy at both high and low velocities. the sensitive balanced vane wheel rotates. freely in response to air flows. conventional twisted vane arms eliminate the source of unreliability, see figure (9). fig. 9. digital anemometer. 3.9.3. thermocouples circuit the thermocouple circuit consists of a digital electronic thermometer (type tm-200, serial no. 13528) as shown in figure (4), connected in parallel to the thermocouples by leads through a thermometer, and digital thermometer calibration (type tm-300, serial no.13645) by using only calibration digital electronic thermometer. thermocouple (type k), this type can be used in temperature range from -200 to 1300 ْ c,(chromel 90 % ni10% cr ; alumel 95%ni2% al 3%mn). 3.9.4. flow meter to measure the average flow rate of hot water , a rota meter which is a flow meter containing a calibrated glass tube and a float [0.27 m 3 /hr] and a globe valve was used to control the average flow rate of hot water, see figure (10). wisam abed kattea al-khwarizmi engineering journal, vol. 8, no.2, pp 12 -29 (2012) 22 0 40 80 120 160 200 boiling point temperature ( c) 0 1 2 3 4 5 6 7 8 m . v o lt a b c d e a aceton b ethanol c distilled water d orthoziline e xylene o 0 40 80 120 160 200 boiling point temperature ( c) 0 40 80 120 160 200 t e m p e r a tu r e w it h l e a d ( c ) a aceton b ethanol c distilled water d orthoziline e xylene a b c d e o o fig. 10. flow meter. 3.10. calibration of instruments 3.10.1. thermometer calibration this is a two in one device including type k thermometer and type k thermocouple calibrator. it is a calibrating process device and measuring process signals. microprocessor circuit assures high accuracy and provides special function and features. built-in temperature linearity compensation high precision circuit is fitted with standard k input measuring socket. it is used to calibrate the other calibratable digital thermometers see figure (4). 3.10.2. anemometer calibration the vane-type rotary anemometer is calibrated just after the duct test section because of the large cross-sectional area of the probe, in the free stream of the outlet region, for the five reynolds numbers. the static-pitot tube with the manometer is used in that calibration, for checking. for many stations, the average velocity (uave) is calculated by integration. the average error percentage for all reynolds numbers range is around 2%. 3.10.3. thermocouples calibration all thermocouple were used with leads and calibrated using the melting point of ice made from distilled water as reference point and the boiling points of several pure chemical substances. the calibration results are given in table (1) and figure (11a &11b). table 1, experimental accuracies. independent variables (v) uncertainty interval (w) surface to bulk air temperature ± 0.16 ْ c voltage of the heater ± 0.04 volt current of the heater ± 0.0003 amp hydraulic diameter ± 0.0002 m velocity ±0.2% m/s thermometer ± (0.2 % + 0.5 c) fig. 11. a. thermocouple calibration results. wisam abed kattea al-khwarizmi engineering journal, vol. 8, no.2, pp 12 -29 (2012) 23    nx nyx x y y in dxdyum 1 1 *2.1 fig. 11. b. thermocouple calibration results. 3.11. velocity measurement one method to measure and calculate the velocities in this research was the direct measurement by the anemometer, it is used to calculate the streamwise velocity (ui). the velocity was determined according to [27]. these velocities were used in calculating the reynolds number and the airflow rate. the mass flow rate for the different flows is calculated from the following:    nx nyx x y y in dxdyum 1 1  …(1) where the uin is the inlet streamwise velocity and it is not constant across the duct height but it has a specific profile. …(2) so the volumetric flow rate is: /mq   …(3) 3.12. temperature measurement temperature distribution at various stations and points inside the duct at inlet and outlet of water inside heat exchanger . however temperatures distribution before vortex generators and after heat exchanger in the test section, infrared thermometers and type k thermocouple. the temperature measurement devices were calibrated. 3.13. procedure 1. connect heat exchanger to hot water supply. 2. set hot water temperature. 3. 3-plant two thermocouples in air duct to measure inlet and outlet air temperature. 4. plant two thermocouples to measure inlet and outlet hot water temperature inside heat exchanger. 5. set water flow rate as desired. 6. switch on fan. 7. switch on circulation pump. 8. 8-take reading every 50 min after steady state condition. 3.14. data analysis simplified steps were used to analyze the heat transfer process for the air flow and water in heat exchanger. the local heat transfer coefficient can be obtained as]28[: hx x )t(x)(t q bs   …(4) q=m ° cp δt q=heat flux x )t( b = local bulk air temperature. x )t( s = local tube surface temperature. all the air properties are evaluated at the mean film air temperature 2 )t(x)(t )(t b f s s s   …(5) f t = local means film air temperature. the local nusselt number (nuz) then can be determined as: nux k dh hx   …(6) where: k=thermal conductivity of air dh=hydraulic diameter of duct p a h d 4  the average values of nusselt number num can be calculated as follows:  l o m dxxnu l nu 1 …(7) the average values of the other parameters can be calculated based on calculation of average tube wisam abed kattea al-khwarizmi engineering journal, vol. 8, no.2, pp 12 -29 (2012) 24 surface temperature and average bulk air temperature as follows:     lx 0x xss dx)(t l 1 t …(8)     lx 0x dx)t ( l 1 t bb x …(9) 2 tt t b f s   …(10) rem μ duρ hin …(11) where; /av i  n u , lha all the air physical properties ρ, μ and k were evaluated at the average mean film temperature ( f t ). 4. results and discussion 4.1. introduction the restriction on shape and position of a duct strongly influences fluid flows along the duct. the main results from the experimental are used in this research, for a fully developed turbulent flow in a rectangular duct for different reynolds numbers and they are presented graphically. 4.2. experimental results experimental study was carried out at reynolds number equal to (62000-125000) for all shapes of vortex generators. the location of the winglets was changed according to longitudinal distance to get the best location of vortex generators at xm=0.5 cm at circular shape and xm=2.5 at square shape. 4.3. the effect parameters on the heat transfer finding many parameters effect on the heat transfer coefficient, i will recogniz the nusselt number reference to enhance the heat transfer from the heat exchanger as shown below. 4.3.1. vortex generator shape effect figures (12,13,14) represent the relation between nusselt number and flow reynolds number at location (x=0.5, 1.5, 2.5cm) respectively, as shown nusselt number increases higher by inserting circular and square vortex generators with respect to without turbulator but the increase in nusselt number is shown to be highest at reynolds number also it indicates that the circular vortex generators at location (x=0.5,1.5 cm) increases nusselt number with respect to the square vortex generators with ratios (28.5%, 13.5% ) respectively, because the turbulence flow in the circular vortex generators greater than the square vortex generators is leading to enhancement the heat transfer in the circular shape better than the square shape . the square vortex generators at location (x=2.5 cm) increases nusselt number with respect to the circular vortex generators with ratio (29.5%). the circular vortex generators at location (x=0.5, 1.5, 2.5cm) increases nusselt number with respect to without turbulator with ratios (56%, 50%, 36%) respectively, and the square vortex generators at location (x=0.5, 1.5, 2.5cm) increases nusselt number with respect to without turbulator with ratios (39%, 42%, 51%) respectively for both cases the general equation of this relation is given as equations 12 and 13 for figures 15 and 16 respectively. nu= ]-21757(x/l) 2 4693.8(x/l) + 35.454 [+ ] 0.855(x/l) 2 + 0.063(x/l) + 0.002 [re + ]-9 × 10 -6 (x/l) 2 6 × 10 -21 (x/l) + 1 × 10 -8 [*re 2 (circular) …(12) nu= ] 27720(x/l) 2 4766.7(x/l) 187.18 [ + ] -0.45(x/l) 2 + 0.066(x/l) + 0.0069 [ re + ]2 × 10 -22 (x/l) 2× 10 -8 [ re 2 (square) … (13) where:x: location of vortex generator. l: the distance before heat exchanger. wisam abed kattea al-khwarizmi engineering journal, vol. 8, no.2, pp 12 -29 (2012) 25 0 100 200 300 400 500 600 700 50000 60000 70000 80000 90000 100000 110000 120000 130000 re n u circular square without turbulator fig. 12. experimental variation of nusselt number with reynolds number at location (x=0.5 cm) for vortex generators. 0 100 200 300 400 500 600 700 50000 60000 70000 80000 90000 100000 110000 120000 130000 re n u circular square without turbulator fig. 13. experimental variation of nusselt number with reynolds number at location (x=1.5 cm) for vortex generators. 0 100 200 300 400 500 600 700 50000 60000 70000 80000 90000 100000 110000 120000 130000 re n u circular square witout turbulator fig. 14. experimental variation of nusselt number with reynolds number at location (x=2.5 cm) for vortex generators. 4.3.2. location of vortex generator figures (15, 16) show the relation between nusselt numbers (with vortex generators, and without vortex generators) for both cases (circular and square) respectively and flow reynolds number. as shown in these figures the behavior is the same as that obtained in figure (12, 13, and 14). but the heat transfer process in circular shape is better than in square shape at location (x=0.5, 1.5 cm) , the square vortex generators at location (x=2.5 cm) is better than circular shape because the square vortex generators in this location provide turbulence flow better than the circular shape as shown in figures. 0 100 200 300 400 500 600 700 50000 60000 70000 80000 90000 100000 110000 120000 130000 re n u x= 0.5 cm x= 1.5 x= 2.5 cm fig. 15. experimental variation of nusselt number with reynolds number at circular vortex generators. 0 100 200 300 400 500 600 700 50000 60000 70000 80000 90000 100000 110000 120000 130000 re n u x= 0.5 cm x=1.5 cm x= 2.5 cm wisam abed kattea al-khwarizmi engineering journal, vol. 8, no.2, pp 12 -29 (2012) 26 fig. 16. experimental variation of nusselt number with reynolds number at square vortex generators. 4.3.3. reynolds number figures (12, 13, 14, 15, and 16) show that nusselt numbers are enhanced with reynolds number increasing for all cases due to increase the inlet velocity (uin) and that will increase the heat transfer from the heat exchanger. 5. conclusion and recommendations 5.1. conclusion experimental study for heat transfer around heat exchanger using vortex generators (circular and square) in turbulent flow has been done. in the experimental study, an apparatus was set up to measure the velocity and temperatures around the heat exchanger with constant heat flux using two shapes of vortex generators at a fixed point. 1there is an effect for the shapes of vortex generators on heat transfer,temperatures and velocity distribution. 2circular shape is the best shape for enhancing heat transfer and the square shape gives minimum heat transfer in the present work. 3heat transfer is enhanced (36-56) % when circular shapes of vortex generators are used. 4heat transfer is enhanced (39-51) % when square shapes of vortex generators are used. 5heat transfer increases by using circular shape when the distance of vortex generators is equal to (xm= 0.5, 1.5 cm) before heat exchanger. 6heat transfer increases by using square shape when the distance of vortex generators is equal to (xm= 2.5 cm) before heat exchanger. 5.2. recommendation for future work the following points can be recommended for future work. 1. numerical investigation can be extended to consider 2-d or 3-d problems. 2. other shapes of vortex generators can be investigated numerically and experimentally (ellipsoidal, trapezoidal, triangle, rectangular) 3. new fixed location for vortex generators and angle (in front of heat exchanger) can be used. 4. the effect of area can be taken into consideration. 5. replace air with steam and study its characteristics. 6. compare the turbulence model used in this research with les (large eddy simulation) turbulence model. 7. increasing the number of vortex generators fixed in each study. notation symbol description unit a tube surface area m 2 cp specific heat at constant pressure j/kg.ºc dh hydraulic diameter m h coefficient of heat transfer w/m 2 .ºc k thermal conductivity w/m.ºc l length of tube m m volumetric flow rate m 3 /s t air temperature at any point ºc symbol description unit tb bulk air temperature ºc tf mean film air temperature ºc ti air temperature at tube entrance ºc ts tube surface temperature ºc u axial velocity component m/s uin axial velocity at tube entrance m/s xm longitude distance cm dimensionless groups symbol description equation nu nusselt number k hdh pr prandtal number k c p re reynolds number  hi du subscript wisam abed kattea al-khwarizmi engineering journal, vol. 8, no.2, pp 12 -29 (2012) 27 symbol meaning s surface a air i inter h hydraulic diameter x local f film m meter greek letters symbol description unit μ dynamic viscosity kg/m.s ν kinematics viscosity m 2 /s ρ air density at any point kg/m 3 abbreviation symbol description b.l boundary layer v.g vortex generator h.e heat exchanger dx horizontal distance of winglet dy vertical distance of winglet 6. references [1] geiser, p. and kotteke, v., “pressure loss, local coefficient of heat transfer in plat and finned tube heatexchanger”,germany.www.link.aip.org/li nk/jhtrao/126/826-pdf, (2000). 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[11] j. r. maughan and f. p. incropera, “regions of heat transfer enhancement for laminar mixed convection in a parallel plate channel”, int. j. heat mass transfer, vol. 33, no.3, pp.555-570,(1990). [12] v. k. migai and i. s. nosova, “decreasing vortex losses in channels”, thermal engineering, vol.26, no.7, pp.423-425, (1979). [13] v. kottke, “ taylor-goertler vortices and their effect on heat and mass transfer ”, heat transfer proceedings of the eighth international heat transfer conference, vol.3, pp.1139-1144,(1986). [14] l.c.g pimentel, r.m.cotta, s.kakac, “fully developed turbulent flow in ducts with symmetric and asymmetric rough walls”, chemical engineering journal, vol.74, pp.147-153, (1999). [15] chien-nan lin,jiin-yuh jang, “conjugate heat transfer and fluid flow analysis in fin-tube heat exchangers with wavetype vortex generators ”,journal of enhanced heat transfer,vol.9,pp.123-136, (2002). [16] s.m. pesteei, p.m.v. subbarao, r.s. agarwal,“experimental study of the effect http://www.link.aip.org/link/?jhtrao/126/826-pdf http://www.link.aip.org/link/?jhtrao/126/826-pdf http://www.link.aip.org/link/?jhtrao/126/826-pdf mailto:sohalms@inel.gov wisam abed kattea al-khwarizmi engineering journal, vol. 8, no.2, pp 12 -29 (2012) 28 of winglet location on heat transfer enhancement and pressure drop in fin-tube heat exchangers”, applied thermal engineering vol.25, pp.1684–1696, (2005). [17] k. torii, k.m. kwak, k. nishino, “heat transfer enhancement accompanying pressure-loss reduction with winglet-type vortex generators for fin-tube heat exchangers”, international journal of heat and mass transfer, vol .45, pp.3795–3801, (2002). [18] ajoardar, a.m. jacobi, “impact of leading edge delta-wing vortex generators on the thermal performance of a flat tube, louvered-fin compact heat exchanger”, international journal of heat and mass transfer, vol.48, pp.1480–1493, (2005). 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[27] fuijta, h. and yokosava, h., “the numerical prediction of fully developed turbulent flow and heat transfer in a square duct with two roughened facing walls”, nagoya university, nagoya, japan, (1984). [28] mohmood, g.i., ligrani, p.m., and won, s.y. ,“spatially-resolved heat transfer and flow structure in a rectangular channel 45oangled rib turbulators”, proceedings of asme turbo expo, (2002) wisam abed kattea al-khwarizmi engineering journal, vol. 8, no.2, pp 12 -29 (2012) 29 دراسة عمهية عن تأثير شكم ومىقع مىنذات انذوامات عنذ مذخم انمبادل انحراري وساو عبذ كاطع انجايعت انخكُٕنٕجٛت / قسى ُْذست انًكاٌ ٔانًعذاث wisam_bd@yahoo.com :انبرٚذ األنكخرَٔٙ الخالصة يٕاقع عُذ انحرارة ٔ اَخقال انجرٚاٌ عهٗ ( انًربعت انشبكت، انذائرٚت انشبكت )انذٔاياث يٕنذ حأثٛر نفحص أجرٚج عًهٛت دراست (x = 0.5, 1.5, 2.5 cm) 62000 قبم يبادل حرار٘ ضًٍ يذٖ نرقى رُٕٚنذ< re < 125000 ٘3000 ٔ فٛض حرار ≤ q ≤ 8000 w/m2. ٙف .انذراست انعًهٛت حى َصب ٔ صٛاَت جٓاز يخخبر٘ نقٛاس انسرعت ٔ درجت انحرارة حٕل انًبادل انحرار٘ ِّه انشبكت انذائرٚت ْٙ األفضم نعًهٛت . أأٓرث انُخائئ أٌ نٕجٕد يٕنذ انذٔاياث اثر بٛر عهٗ ححسٍٛ اَخقال انحرارة ٔٚعخًذ ْها عهٗ كم انًٕنذ ٔيٕقع قبم انًبادل [xm=2.5 cm] انشبكت انًربعت ْٙ األفضم نعًهٛت َقم انحرارة عُذ يٕقع . قبم انًبادل انحرار٘[xm=0.5 cm] َقم انحرارة عُذ يٕقع .انحرار٘ ححسٍ فٙ اَخقال انحرارة حٕل انًبادل أأٓرث ْهِ انًقارَت. قٕرَج انُخائئ انعًهٛت فٙ حانت ٔجٕد يٕنذ انذٔاياث يع عذو ٔجٕد يٕنذ انذٔاياث عهٗ انخٕانٙ بأسُخذاو يٕنذ انذٔاياث انذائر٘ انشكم َسبتً انٗ عذو ٔجٕد ( x=0.5, 1.5, 2.5cm) عُذ يٕاقع (%36 ,%50 ,%56) انحرار٘ بُسب عهٗ انخٕانٙ بأسُخذاو ( x=0.5, 1.5, 2.5cm)عُذ يٕاقع (%51 ,%42 ,%39) عٕائق جرٚاٌ،ٔاَخقال انحرارة حٕل انًبادل انحرار٘ ٚخحسٍ بُسب .يٕنذ انذٔاياث انًربع انشكم َسبتً انٗ عذو ٔجٕد عٕائق جرٚاٌ mailto:wisam_bd@yahoo.com (2012 )12 29 ، صفحة2، انعذد 8 مجهة انخىارزمي انهنذسية انمجهذوساو عبذ كاطع 30 al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 4550 (2015) study tensile strength and wear rate for unsaturated polyester resin and nitrile butadiene rubber polymer blend entihaa g. daway mechanical department/ technical institute/ kut email: entihaa.gatea@yahoo.com (received 2 june 2014; accepted 25 january 2015) abstract binary polymer blend was prepared by mechanical mixing method of unsaturated polyester resin with nitrile butadiene rubber (nbr) with different weight ratios (0, 5, 10 and 15) % of (nbr). tensile characteristics and wear rates of these blends were studied for all mixing ratios. the microstructure of fracture surfaces of the prepared samples were investigated by optical microscope. the results were showed that strain rates of the resin material increase after blending it with rubber while the ultimate tensile strength and young’s modulus values of it will decrease. it is also noticed that the wear rate of resin decreases with increasing of (nbr) content. keywords: polymer blend, tensile strength, wear rate, unsaturated polyester, nbr. 1. introduction development of new resin systems to meet demands for high performance materials would undoubtedly take too long and would certainly be too expensive since it would require huge investments in totally unexplored technologies and new plant facilities. an alternative to the development of new polymers is the development of alloys and blends that are a physical combination of two or more polymers to form a new material [1]. two or more existing polymers may be blended for various reasons. one reason is to achieve a material that has a combination of the properties of the constituents, e.g. a blend of two polymers, one of which is chemically resistant and the other tough. another reason is to save costs by blending a high-performance polymer with a cheaper material. a very important use of blending is the combination of an elastomer with a rigid polymer in order to reduce the brittleness of the rigid polymer [2, 3]. abi santhosh aprem et al. investigated the influence of hygrothermally -degraded polyester urethane hd-pur on cure characteristics, mechanical, dynamic-mechanical and morphological characteristics of chloroprene rubber (cr). the presence of primary and secondary amines in hd-pur, did not increase the cure rate of cr. the mechanical properties of chloroprene vulcanizates were improved upon hd-pur addition. the strain-induced crystallization of cr did not show any deviation upon the addition of hd-pur. crosslink densities calculated from swelling studies, stress–strain behavior and modulus measurements are found to increase upon hdpur addition and showed similar trend. scanning electron microscopic studies have been done in order to have an insight into fracture behavior of the samples and to analyze the microstructure of the blends [4]. soares et al. studied the influence of dynamic vulcanization and blend composition on the free volume properties of polypropylene (pp)/ nitrile butadiene rubber (nbr) blends by using a novel technique based on positron annihilation lifetime spectroscopy (pals). the results indicate that the pp/nbr blends are so incompatible that the dynamic vulcanization was not enough to improve the mechanical properties. however, there are morphological differences at the molecular level mailto:entihaa.gatea@yahoo.com entihaa g. daway al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 4550 (2015) 46 with the vulcanization, which can be easily detected by the pals technique [5]. antaryami mishra prepared a composite from epoxy with weight percentages of 10, 15, and 20 % of rubber dust (weight fractions of 9, 13 and 17 % respectively). the pins were tested in a pin-ondisc wear monitor to determine the co-efficient of friction and weight losses with varying speeds, loads and time. the wear volume and wear rates have also been found out for all these three specimens. it is observed that all the specimens have exhibited very low coefficient of friction and low wear rates under dry sliding condition. out of the above three samples tested, the specimen with 10 % rubber dust by weight has shown lowest wear rates. however a peculiar result i.e decreasing trend has been obtained with 20% reinforcement of rubber in epoxy while rubbed against steel at varying speeds [6]. onyeagoro studied the cure characteristics and mechanical properties of reactive compatibilized natural rubber (nr)/carboxylated nitrile rubber (xnbr) blends using maleic anhydride-graftedpolyisoprene (mapi) and epoxy resin (epx) dual compatibilizers. the results show that mapi/epx dual compatibilizers exhibit beneficial effect by decreasing the cure time and increasing the scorch time of the nr/xnbr blends and increasing compositions of xnbr brought decreases in tensile strength, tear strength and elongation at break. however, these properties increased in the presence of mapi/epx dual compatibilizers [7]. this paper reports a study on the effect of adding nitrile butadiene rubber (nbr) on the tensile properties and wear rate of unsaturated polyester resin (upe). 2. experimental 2.1. materials  unsaturated polyester resin (upe) and its curing agent, methyl ethyl ketone peroxide (mekp) was supplied by saudi industrial resins (sir) company, saudi arabia.  nitrile butadiene rubber (nbr) was supplied by babylon tires factory in babylon, iraq. toluene was used to dissolve the pieces of rubber (nbr) for 24hour in sealed container. 2.2. preparation of samples the polymers used in this work for preparing blends are unsaturated polyester resin, which mixed with 2% of hardener and 0.5% of accelerator, and nitrile butadiene rubber (nbr) which dissolved in toluene. binary polymer blends specimens were prepared at different weight fractions of (0, 5, 10 and 15) % of nbr. mechanical mixer was used to prepare binary blend and after that the blend poured in a mold which made from aluminum with dimensions (14×12×4) cm. when the solidification process was completed the samples were cut according to the standard procedure for fulfilling the specific tests. figure (1) shows photographs of tensile and wear specimens. fig. 1. samples dimensions and photographs of tensile and wear samples. 2.3. mechanical properties the tensile properties were measured using an instron machine at a crosshead speed (4 mm/min) according to astm d638. 2.4. wear test wear test for binary polymer blend have been conducted using (pin –on –disc) testing according to astm g99. the disc has angular velocity (500rpm) and manufactured from toolset with (55hrc) hardness. wear test have been carried entihaa g. daway al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 4550 (2015) 47 out under the normal load (5n) with varying time and pin weight loss has been measure by using sensitive electronic balance (type-ae160 metler,4 digits). the wear rates are calculated according to the following equations [8]: 𝑊𝑅 = ∆𝑊 𝑆𝐷 ... (1) ∆𝑊 = 𝑊1 −𝑊2 ... (2) 𝑆𝐷 = 2𝜋𝑟𝑛𝑡 … (3) where: wr: is the wear rate (g/cm) w1, w2: are the weights of specimens before and after wear test (g) sd: is the sliding distance (cm) r : is the disc radius (7cm) n: is the number of disc cycles (500 rpm) t: is the time of test 2.5. optical microscope optical microscope (japanese type) was used for studying the morphology and fracture surfaces for samples at a magnification of 400x. 3. results and discussion 3.1. stress-strain behavior tensile properties of pure polymer and its blends are present in figure (2) from this figure it can be notice that the (stress-strain) behavior of pure (upe) is linear because of the brittleness of this resin, but after blending it with (5, 10, 15) wt. % of nbr, the behavior become non-linear this related to the nature of added rubber (nbr) which transform the material from elastic state to plastic one. figure (3) shows that the upe has higher value of tensile strength and this value decrease with increasing of nbr content, this may be related to the fact that polyester resin are more rigid than nbr which is soft and elastic and behaves as viscoelastic material so that the increasing of weight percentage of nbr lead to decrease value of tensile strength for unsaturated polyester. the results for young's modulus (e) are shown in figure (4), it can be noticed that the (e) value of upe decreases when rubber content increased, this is due to that elastomers have characteristic low modulus[9] as well as unsaturated polyester have high stiffness than that for nbr[10].the results of this test agree with that for paulo at el.[11] who investigated the modification of unsaturated polyester by adding rubber powder produced from scrap tires and study its mechanical properties. the results clearly show that decrease in modulus due to the introduction of a soft rubber phase which has lower modulus and higher ultimate strain value compared with unsaturated polyester. fig. 2. stress-strain curve for upe and its polymer blends. fig. 3. tensile strength of nitrile rubber (nbr) modified resin (upe). fig. 4. young's modulus of nitrile rubber. percentage of nbr (%) y o u n g 's m o d u lu s (m p a ) 0 50 100 150 200 250 300 0 5 10 15 20 0 5 10 15 20 25 0 5 10 15 20 percentage of nbr (%) t en si le s tr e n g th (m p a ) strain s tr es s (m p a ) 0 5 10 15 20 25 0 0.1 0.2 0.3 upe (95\5)% upe\ nbr (90\10)% upe\ nbr (%) entihaa g. daway al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 4550 (2015) 48 3.2. wear rate figure (5) shows the variation of wear rate with sliding time. from this figure, it can be observed that the unsaturated polyester resin have high wear rate when compared with blend this may be attributed to the generation heat of friction during sliding motion that made the specimen softer. the generated heat softened and removed the surface layer of material during the sliding test [12]. generally the value of wear rate decrease with increasing of nbr content when time of sliding will increase. it is necessary to mention that the sample with ration (15%nbr) failed under wear test; this may be related to the nature of interpenetrating between the two polymers networks at this percentage which is defined (incompatible polymer blend) leading to decrease the mechanical properties of material [13 ]. fig. 5. variation of wear rate with sliding time for nitrile rubber (nbr) modified resin (upe). 3.3. optical microscope from fig.s (6 and 7), it can be noticed that the nature of fracture surfaces for (pure upe) and the blend with (5% of nbr) are smooth, bright like mirror which indicates to the brittle fracture where cracks spread rapidly with little or no plastic deformation while it is clearly that the fracture surface will change to become dull and fibrous after blending (upe) with (10 and 15)% of (nbr) as shown in fig.s (8 and 9), this means that the material behavior could be transformed to become ductile at these ratios of mixing. also, it is obviously that there are two regions were found (white and dark) as shown in fig.(9) where the white region is a brittle material (upe matrix)while the dark region is (nbr rubber). this phenomenon means that the rubber particles agglomerate as spheres forms at this ratio of mixing (15%) which lead to little plastic deformation before facture of sample because of these particles act as an energy absorber and improve the toughness of material. these results were similar to those reported in the literature [14]. most authors have used a nucleation-growth mechanism to describe these morphologies which lead to the phase separation between the two polymers [15]. fig. 6. optical micrograph of fracture surface for pure(upe) after tensile test. fig. 7. optical micrograph of fracture surface for nitrile rubber (5%nbr) modified resin (upe) after tensile test. fig. 8. optical micrograph of fracture surface for nitrile rubber (10%nbr) modified resin (upe). w ea r ra te × 1 0 -7 ( g m /c m ) sliding time (min) entihaa g. daway al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 4550 (2015) 49 fig. 9. optical micrograph of fracture surface for nitrile rubber (15%nbr) modified resin (upe). 4. conclusions 1it can be obtaining on toughened (upe) by mixing it with weight ratios ranged (10-15) %wt. of (nbr). 2the values of tensile strength and young’s modulus of (upe) decease after blending it with (nbr). 3wear rates of (upe) with sliding time of (upe/nbr) blend decrease compared with its value for pure resin (upe). 4from micrographs of optical microscope, it is clear that the transformation of material behavior is obtained at mixing ratio more than 10%wt. of (nbr). 5. references [1] robert o. ebewele ," polymer science and technology" copyright by crc press llc, (2000). [2] david i. bower, "an introduction to polymer physics" copyright d. i. bower, (2002). [3] l. a. utracki," polymer blends handbook", klwer academic publishers, netherlands, (2002). [4] abi santhosh aprem , seno jose , sabu thomas, nektaria marianthi barkoula , j. kargerkocsis," european polymer journal ", vol.39, pp.(69–76) (2003). [5] b.g. soares, m.s.m. almeida, c. ranganathaiah, m.v. deepaurs, siddaramaiah," polymer testing ", vol.26, pp. (88–94), (2007). [6] antaryami mishra," world academy of science, engineering and technology ", vol.6, pp. (579-584) (2012). [7] g.n.onyeagoro,"international refereed journal of engineering and science (irjes)", vol. 2, pp. (7-16), (2013). [8] awham m. h., sadeer m. m., bushra h. m.," eng. & tech. journal", vol. 28, pp. (5165-5170), (2010). [9] [9] m.o. munyati, p.a. lovell," e-polymers ", vol.10, pp. (547-556), (2010). [10] robert a. shanks ,ing kong , " general purpose elastomers: structure, chemistry, physics and performance", springer-verlag berlin heidelberg, (2013). [11] paulo j. r. o. nóvoa ,antónio j. m. ferreira , antónio torres marques," materials science forum ", vols. 514-516, pp.( 662-665), (2006). [12] s.a.r. hashmi, u.k. dwivedi, navin chand," wear ", vol.262, pp. (1426–1432) ,(2007). [13] poonam tiwari, pratibha singh, k. n. pandey, vishal verma, vijai kumar," international journal of chemical studies",vol.1,pp.(54-64),(2013). [14] zhou l., wang x., lin y., yang j., wu q., "journal of applied polymer science ", vol. 90, pp. (916-924), (2003). [15] moschiar s. m., riccardi c.c., "journal of applied polymer science", vol.42, pp. (717-735), (1991). dark region white region (2015) 4550، صفحة 2، العذد11دالخىارزمً الهنذسٍة المجلجلة م انتهاء قاطع دواي 50 ومطاط دراسة مقاومة الشذ و معذل البلى لخلٍط بىلٍمري من راتنج البىلً استر غٍر المشبع ناٌتراٌل بٍىتادٌٍن أنتهاء كاطع دواي كىث /انًعهذ انتقٍُ/ قسى انًُكاَُك entihaa.gatea@yahoo.com : االكتروٍَ انبرَذ الخالصة وبُسب وزَُت يختهفت يٍ انًطاط( َاَتراَم بُىتادٍَُ)استرغُرانًشبع يع يطاط تى تحضُر خهُظ بىنًُرٌ ثُائٍ بطرَقت انخهظ انًُكاَُكٍ نراتُج انبىنٍ واستخذو انًجهر انضىئٍ نفحص انبُُت انًجهرَت . وقذ تى دراست خصائص انشذ ويعذالث انبهً نتهك انخالئظ نجًُع َسب انخهظ( %. 5،10،15، 0) نشذ لانقصىي ةقُىالاظهرث انُتائج باٌ يعذالث االَفعال نهًادة انراتُجُت تسداد بعذ خهطها يع انًطاط فٍ حٍُ تُخفض . نهًُارج انًحضرة نسطىح انكسر (.nbr)كًا نىحع باٌ يعذل انبهً َتُاقص يع زَادة يحتىي انًطاط . ويعايم َىَك نها mailto:entihaa.gatea@yahoo.comالبريد mailto:entihaa.gatea@yahoo.comالبريد <4d6963726f736f667420576f7264202d20312d39cdd3ede420c7e1dae1dfc7e6ed20e6dae1ed20dac8cf20c7e1ccc8c7d1> al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 15, no. 1, march, (2019) p.p. 19 improvement of mechanical and fatigue properties for aluminum alloy 7049 by using nano composites technique alalkawi h. j. m* ali yousuf khenyab** abduljabar h. ali*** *department of electromechanical engineering/ university of technology/ baghdad/ iraq *** ministry of higher education and scientific research/ baghdad/ iraq *email: alalkawi2012@yahoo.com **email: al2024t4@gmail.com ***email: dr.abduljabarha@yahoo.com (received 24 january 2018; accepted 14 august 2018) https://doi.org/10.22153/kej.2019.08.001 abstract the aim of present work is to improve mechanical and fatigue properties for aluminum alloy7049 by using nano composites technique. the zro2 with an average grain diameter of 30-40 nm, was selected as nano particles, to reinforce aluminum alloy7049 with different percentage as, 2, 4, 6 and 7 w �%. the stir casting method was used to fabricate the nano composites materials due to economical route for improvement and processing of metal matrix composites. the experimental results were shown that the adding of zirconium oxide (zro2) as reinforced material leads to improve mechanical properties. the best percentage of improvement of mechanical properties of 7049 aa was with 4% wt. of zro2 about (7.76% ��) for ultimate tensile stress uts, (9.62% ��) for yield stress ys and (9.92%) for hardness hb than other of adding of 2, 6 and 7% of zro2. also the results shown that the fatigue strength of 7049 aa with 4 w �% zro2 nanoparticles is higher than that of 7049 aa under constant loading 9.86% at 108 cycles as well as the fatigue life factor (iflf %) at different amplitude stress 400, 350, 300 and 250 mpa was improvement in range 66, 115, 63 and 107% respectively. keywords: nanomaterial, 7049 aa, zro2, stir casting. 1. introduction only few machine parts are subjected to static loading and the majority of machine parts are subjected to variable loads. experimentally, when a material is subjected to dynamic loads, it fails at a stress below the yield stress, such type of failure is known as fatigue. fatigue may occur under constant or variable loads. constant fatigue loading is defined as fatigue under cyclic loading with constant amplitude and a constant mean stress or load. but in service, the structures or components are subjected to variable amplitude loading, which can be a rather complex load time history [1]. many techniques were used to improve mechanical and fatigue properties for metal materials such as surface cold work, shot penning and laser shock penning……etc. [2, 3 and 4]. the aim of present work is improved mechanical and fatigue properties for aluminum alloy7049 by nano composites technique. the nano composites material was fabricated by stir casting method using aluminum alloy7049 as a metal matrix and nano particles of zro2 as a reinforced material with different weight percentage, 2,4,6 and 7w �%. metal matrix composites were studied which are widely used in an industry for many applications in aerospace, automotive and others so it is request to improve mechanical and fatigue properties of metal matrix composites for use in highperformance applications. m. dinesh and r. ravindran [5] studied hardness and tensile behavior of 7075 aluminum alloy with different reinforcement by cr alalkawi h.j.m al-khwarizmi engineering journal, vol. 15, no. 1, p.p. 19 (2019) 2 nanoparticles weight as 2,3,4,5 and 6 w �% and zinc nanoparticle of 1 w �% by air casting technique. they found the tensile stress and hardness values of the composite higher than the unreinforced alloy. the stir casting was suitable technique for manufacture of this type of composite material. c. kannan and r. ramanujam [6], studied nano composite al-7075 alloy for two conditions, single and hybrid for 2 w �% and 4 wt.% of sic produced through stir casting. they observed that the addition of nanoparticles with 30-50 nm grain size, improved the ultimate stress and hardness by 63.7% and 81.1% for single and hybrid respectively. divagar, and m. vigneshwar [7] "fabricate 7075-t651 alalloy with various weight percentages of sic nanoparticles 5,10 & 15 w � % of a1203 nanoparticles as reinforcements by stir casting process. the metal matrix nanocomposite comprising of aa7075t651+sic-10%+al2o3-5% exhibits 12.13% higher fatigue strength than the base metal and other composites. s.e.shin and d. h. bae [8] studied fatigue behavior of aluminum alloy 2024 matrix composites reinforced with multi-walled carbon nanotubes under the tension-compression fatigue test. tensile and fatigue strength of the al2024 composites increases with increasing multiwalled carbon nanotubes content. al 2024 with 4vol.% multi-walled carbon nanotubes composite shows the remarkably enhanced fatigue strength of 600 mpa at the 2.5×106 cycles and the ratio of tensile strength to fatigue strength of 0.78. when the composite is cyclically loaded, the developed incompatibility between the matrix and the fiber induces the fiber pull-out and it acts as a bridge when the cracks propagate. thus, as the content of multiwalled carbon nanotubes increases in the composite, the prevailing bridging behavior of multi-walled carbon nanotubes enhances the number of fatigue cycle. al-alkawi h. j. m. and ibtihal a. [9] studied the behavior of 2024 aluminum alloy with a12o3 nano composite which was fabricated by stir casting at 450 r.p.m and casting temperature of 850°c. the experimental tests showed an improvement in the fatigue strength and life compared to the metal matrix 2024 aluminum alloy. the s-n curves were obtained and the equations of the nano composite which described the constant s-n curves were established based on basquin power law equation for 0.2, 0.4, 0.6, 0.8 and 1.0w �% a12o3. the experimental results analysis revealed that the fatigue strength is improved by 5.3% and the fatigue life is increased by 16.02% for 2024 aluminum alloy with 0.4w �% a12o3 nano composite compared to that for metal matrix. a.p. utkarsh prajapati et al [10] they studied the effect of nano al2o3 on the mechanical properties of the aluminum based alloy, they concluded that the mechanical properties of aluminum based alloy can be increase by adding al2o3 nano particles into it. also the stirring speed significantly affects the mechanical properties of the nano-scattered castings. the speed more than 1500 rpm causes decrease in the elasticity. the distribution of nano alumina particles in the aluminum from 1.0 to 3.0, the immunization particles are consistently scattered in al, with alumina content under 4.0 wt.%. al alkawi h. j. m. et al [11] investigated 7075 al-alloy metal matrix composites with different w � %, 0.2, 0.4, 0.6, 0.8, and 1.0 of a1203 reinforced particles of 10 nm in grain size, were fabricated using stir casting technique. discuss the influence of adding a1203 particles content on the mechanical properties of the metal material composites. they concluded the nanomaterial reinforcement lead to improve the bhn hardness, ultimate strength �� and yield stress ��.the maximum improvement in bhn hardness, ��and� was observed with 0.2 w �%. a1203.while the minimum value of ductility was obtained with 0.2 w �% a1203. r. senthilkumar et al[12] studied the mechanical and fatigue properties for two different composite material, 90w �% of 2014 aluminum alloy with 10w �% micron size of al2o3 and 90w �% of 2014 aluminum alloy with 8w �% micron size of al2o3 and 2w �% nano size of al2o3. the results show the mechanical and fatigue properties for composite 90w �% 2014 aluminum alloy with 8w �% micron size of al2o3 and 2w �% nano size of al2o3 was higher than that of composite 90w �% 2014 aluminum alloy with 10w �% micron size of al2o3 due to nano size of al2o3 reinforcement which more effectively. al-alkawi et al [13] studied 7075 al-alloy with nanomaterial reinforced ai203 of 10 nm in grain size which is used different w �% as, 0.2 , 0.4 , 0.6 , 0.8 and 1.0. it was observed that the best enhancement in fatigue strength and life occurred with 0.2w �% of ai2o3.the fatigue strength increased by 2.86% compared to the base metal alloy. the improvement may be alalkawi h.j.m al-khwarizmi engineering journal, vol. 15, no. 1, p.p. 19 (2019) 3 coming from uniform distribution of ai2o3 and minimal porosity. hajizamani and baharvandi [14] used hybrid nano composites with a356 aluminum alloy base metal taking four weight percentages 0.5, 1, 1.5 and 2w �% of al2o3 and 10% volume of zro2. the stir casting technique was used for manufacturing the nano composites. they observed experimentally that the mechanical and hardness increased for all the above nano composites in an pproximately linear manner. ali mazahery and mohsen ostadshabani [15] study the vol.% of alumina nanoparticles were incorporated into the a356 aluminum alloy by a mechanical stirrer. characterization of mechanical properties revealed that the presence of nanoparticles significantly increased compressive and tensile flow stress. the presence of nano particle al2o3 reinforcement leads to significant improvement in yield strength and ultimate tensile stress while the ductility of the aluminum matrix is retained. 2. material and properties the material that used in this work was a 7049aa supplied from round bar of 12 mm in diameter. the experimental of chemical and mechanical properties of 7049aa was done at state company for inspection and engineering rehabilitation in iraq sier, which is reported in table-1 and table-2 respectively. table 1, experimental and standard chemical composition of 7049 aa in � �% material zn ti si cu fe cr mg mn al standard 0.25 max. 0.2 max. 0.8 max. 3.5-4.5 0.7 max. 0.1 max. 0.4-1 0.4 0.8 balance experimental 0.22 0.08 0.15 3.8 0.25 0.06 0.72 0.57 balance table 2, mechanical properties of 7049aa property �� �� � �� e � �� µ ei% hb experimental 515 312 73 0.32 19 131 standard 520 317 74 0.32 20 132 3. experimental technique of fabricating the nano composites stir casting method was chosen as technique of fabricating the nano composites due to economical route for improvement and processing of metal matrix composites materials. the 7049 aa was selected as the matrix and zro2 as nano particles, as a reinforced material with different weight percentage, 2,4,6 and 7w �% with an average grain diameter of 30-40 nm. in stir casting process, the 7049 aa was first heated above its melting temperature (750℃), then keep it in the semisolid condition, at the same time the zro2 particles was heated at the same temperature and dropped into semisolid and mixed with 450 r.p.m stirring speed for 4 minutes. the melt was then superheated above liquid temperature and poured into the mold for fabricating the specimens. the test rig which used to prepare the nano composite material can be seen in figure-1. fig. 1. stir casting process; a: furnace ignition and metal melting; b: move the nanoparticles with molten metal; c: the melt poured into the mold; d: composites product into mold. alalkawi h.j.m al-khwarizmi engineering journal, vol. 15, no. 1, p.p. 19 (2019) 4 the size of the composites product is 150 mm length and 12 mm in diameter. the composite product was fabricated in the rule of mixtures which can be seen in table-3. table 3, nanocomposites mixture rule aluminum alloy 7049 (� �) zro2nanoparticles (� �%) zro2 (� �) total weight (� �) 980 960 940 930 2 4 6 7 20 40 60 70 1000 1000 1000 1000 4. fatigue specimens preparation and machine test fatigue specimens were prepared according to din 50113, 12 specimens for 7049 aa and 24 specimens for 7049 aa with 4% wt. of zro2. the specimen dimensions' configuration of fatigue test was shown as in figure-2. the silicon carbide papers were using for smooth surface of the specimen. fig. 2. the specimen dimensions in mm according to (din 50113) standard values a rotating bending machine fatigue–testing schenck product type as shown in figure-3 was used to implement all fatigue tests, with constant and variable amplitude stress. the fatigue specimen which is shown above has a round cross-section and is subjected to an applied load from the right side of the perpendicular to the axis of the specimen, developing a bending moment. therefore, the surface of the specimen is under bending stress, tension and compression when it rotates. fig. 3. fatigue bending machine test schenck. 5. results and discussions 5.1 mechanical properties of composites the experimental of mechanical properties of 7049 aa specimens with using zirconium oxide (zro2) as a reinforced material with different w �% was done at state company for inspection and engineering rehabilitation in iraq sier, which is reported in table-4. the results show the adding of zirconium oxide zro2 as reinforced material lead to improve mechanical properties and hardness. the results show the best improvements for mechanical properties and hardness was for composite with 4w �% of zro2 compared with that the others w �% of zro2 as shown in table-4 and figure-4. the tensile stress-strain diagram up to ultimate stress for 7049aa and nano composite with 4w �% of zro2 was shown in figure-5. table 4, mechanical properties result for composite 7049aa with different � �% of zro2. property �� �� improve. % � �� improve. % hb improve. % 0% 515 ----312 ----131 ---- 2% 534 3.689 320 2.564 136 3.816 4% 555 7.766 342 9.615 144 9.923 6% 540 4.854 332 6.410 138 5.343 7% 532 3.330 328 5.128 132 0.769 alalkawi h.j.m al-khwarizmi engineering journal, vol. 15, no. 1, p.p. 19 (2019) 5 fig. 4. hardness (hb) result with different � �% of zro2. fig. 5. tensile test for 7049aa and nano composite with 4� �% of zro2 . 5.2 fatigue test results under constant loading all fatigue specimens were tested under constant loading using the rotating bending machine fatigue. the fatigue test under constant amplitude stress was for 7049aa without and with 4w �% zro2 only to find the improvement for fatigue properties. the s-n curves results illustrated in table-5 at four different levels stress or amplitude stress. the average of number of cycles to failures of three specimens at each level stress is recorded. it can be observed that the effect of the addition of 4w �% zro2 nanoparticles on fatigue behavior by seen the improvement in fatigue life through estimating the improvement fatigue life factor (iflf %) at different level stress by using equation-1[16]. …(1) where (���) and (���) is number of cycle to failure for base metal or with 0w �%zro2 and for the composite with 4w �% zro2specimens respectively. the (flif %) at different amplitude stress was shown in table-5 table 5, improvement fatigue life factor (iflf) at different amplitude stress. the empirical fatigue power law regression given by: σ � a�� � … (2) where, (σ ) is the applied stress, nf is the number of cycles to failure and (a),(b) are the fitting parameters. the regression constants represent the fatigue trends from the model and the fatigue strength at 108 cycles can be observed as shown in table-6. the results show the improvement of fatigue strength was 9.86%. table 6, fatigue parameters and fatigue strength of aa 7049 with and without 4wt% zro2. description a b fatigue strength at 108 cycles (���) improvement of fatigue strength ( % ) 7049aa 1240 -0.1187 139.370 ---- 7049aa with 4wt% zro2 1283 -0.1154 153.118 9.86 amplitude stress �� average !" of 7049aa without zro2 average !# of 70499aa with 4wt% zro2 iflf% 400 12600 21000 66.66 350 44800 96600 115.6 300 190600 310800 63 250 610800 1268600 107.7 alalkawi h.j.m al-khwarizmi engineering journal, vol. 15, no. 1, p.p. 19 (2019) 6 the s-n curve under constant amplitude stress test for specimens 7049aa without zro2 or with 0w �% zro2 and for the composite 7049aa with 4w �% zro2, and the empirical power law equation it can be shown in figure-6. fig. 6. s-n curves of the nano composite with 4 � �% zro2 compared with the base metal 7049aa with 0% zro2 under constant amplitude stress . the results show the introducing 4% of zro2 to the7049aa lead to the higher mechanical properties, improve the fatigue life and fatigue strength. the higher mechanical properties of the 4wt% zro2 composite could be attributed to the fact that zro2 particles acts as obstacles to the motion of dislocation, the increasing in mechanical properties can be attributed to reduce grain size, leading to rise up the fatigue strength and fatigue life of composites and this results agreement with finding by abdizadeh h., baghchesara m.a. [17]. 5.3 fatigue test results under variable loading fatigue test under variable loading was done by testing specimens under variable loading for two different conditions at low to high sequences loading and high to low sequences loading by using fatigue test machine type rotary, the machine run 10000 cycles for each stress level and so on to the failure of specimen, 6 specimen for each case. experimental fatigue test under variable loading for base metal with 0wt% zro2 and nano composite 4w �%zro2 was recorded in table-7. the results show improvement in fatigue life factor 33.7% and 15.8% of nano composite with 4wt% zro2 for both cases respectively through estimating the improvement fatigue life factor (iflf %) for two cases by using equation-1. table 7, experimental fatigue test under variable loading for base metal with 0wt% zro2 and nano composite 4� �%zro2 loading sequence �� $%&'�(& ! 0wt% zro2 �%&'�(& ! 4wt% zro2 loading program 350-250 37644 56800 350 10000 250 10000 250-350 72600 86233 350 250 10000 10000 0%zro, -.=1240 ! /0.2234 4%zro, -.= 1283 ! /0.2256 alalkawi h.j.m al-khwarizmi engineering journal, vol. 15, no. 1, p.p. 19 (2019) 7 5.3 microstructure analyses microstructures of 7049 aa as received and composites with the content of 4 wt.% zro2, are shown in figures-7, dark regain represent al matrix and bright particles represent particles of zro2. it can be mentioned that nano-particle zro2 represents appropriate wettability with molten metal and good stability as well. it certainly should be noted that not only the wettability has an important role in the distribution of reinforcement particles in the matrix, but also, other factors such as pouring condition, stirring rate, solidification rate, etc. have profound influences on the even distribution of zro2 in the metal matrix, fabricated by stir casting. (a) (b) fig. 7. (a) sem micrograph of 7049aa as received at different magnification 50 and 20μm respectively (b)sem micrograph of composites fabricated of 7049aa with 4wt% zro2 at different magnification 50 and 20μm. 6. conclusions the results show the improvement of using different w �% of zirconium oxide zro2 nano particles reinforced aluminum alloy7049 as nano composites material on mechanical and fatigue properties. the significant findings of this investigation are as follows: 1. the mechanical properties of 7049aa specimens with zirconium oxide (zro2) reinforced material lead to improving mechanical properties and hardness in different percentage according to different w �%of zro2 reinforced 7049aa.the best improvement of mechanical properties and hardness was occurred with 4w �% of zro2 in the rate of (7.76��%) uts, (9.615��%) ys and (9.92%) hb. 2. fatigue properties of 7049aa with 4w �% zro2 are higher than that of the nonreinforced 7049aa under constant loading. also the fatigue life of nano composite with 4wt% zro2 was higher than that for base metal or with 0wt% zro2 under variable loading sequence for both high to low and low to high sequence. 3. the higher mechanical properties of 7049aa with 4w �% zro2 composite could be attributed to the fact that zro2 particles acts as obstacles to the motion of dislocation and particles of zro2 alalkawi h.j.m al-khwarizmi engineering journal, vol. 15, no. 1, p.p. 19 (2019) 8 to reduce grain size, leading to rise up the constant and cumulative fatigue life of composites. 4. the results of fatigue test under variable loading for two different conditions at low to high sequences loading and high to low sequences loading show improvement in fatigue life factor 33.7% and 15.8% of nano composite with 4wt% zro2 for both cases respectively. 7. reference [1] n. e. frost, k. j. marsh and l. p. pook “metal fatigue” clarendon press, oxford (1974). [2] koji takahashi, hiroko osedo, takaya suzuki, shinsaku fukuda, "fatigue strength improvement of an aluminum alloy with a crack-like surface defect using shot peening and cavitation peening" engineering fracture mechanics, vol. 193, pp. 151-161, april 2018. [3] abdul-jabar h. ali, "improvement of fatigue life of aa 7075 using laser shock peening (lsp) surface treatment technique", al-taqani refereed scientific journal, vol. 29, pp. 47-57 (2016). [4] dorman, m., toparli, m. b., smyth, n., cini, a., fitzpatrick, m. e. and irving, “effect of laser shock peening on residual stress and fatigue life of clad 2024 aluminum sheet containing scribe defects”, materials science and engineering: a, 548, pp. 142–151, (2012). [5] m. dinesh, r.ravindran "tensile and hardness behavior of aluminum 7075 and zinc and chromium metal matrix composite by stir-casting route" international archive of applied sciences and technology , vol. 7 , pp. 3946 (2016). [6] c. kannan, r. ramanujam," comparative study on the mechanical and microstructural characterisation of aa 7075 nano and hybrid nanocomposites produced by stir and squeeze casting" contents lists available at science direct journal of advanced research 309–319 8 (2017). [7] s. divagar, m. vigneshwar, s.t. selvamani " impacts of nano particles on fatigue strength of aluminum based metal matrix composites for aerospace" materials today: proceedings, vol. 3, pp. 3734-3739, (2016). [8] s.e.shin, d.h.bae," fatigue behavior of al2024 alloy-matrix nanocomposites reinforced with multi-walled carbon nanotubes" science direct, composites part b: engineering volume 134, , pages 61-68, (1 february 2018). [9] al-alkawi h.j. m., ibtihal a. m., mamoon a. a. aljaafari," an estimation study on fatigue transition life of nanocomposites reinforced by al203"arab universities union general secretary of arab engineering colleges society, (2017). [10] a.p. utkarsh prajapati, a.p. jay h patel, ketul v patel, parthkumar p patel, pujan p bhatt, sandipkumar o varma," effect ofal2o3nano-particleonmechanical properties of aluminum based alloy: a review", iosr journal of mechanical and civil engineering (iosr-jmce) e-issn: 2278-1684, p-issn: 2320-334x, volume 13, issue 2 ver. ii, pp 72-75, (mar. apr. 2016) [11] al-alkawi h.j.m., abthal a. m., mamoon a. a. aljaafari," mechanical properties of 7075 aluminum alloy matrix/al2o3, particles reinforced composites" engineering and technology journal, (2017). [12] r. senthilkumar, n. arunkumar, m. manzoor hussian,"comparative study on low cycle fatigue behaviour of nano and micro a1203 reinforced aa2oi4 particulate" hybrid composites results in physics, vol. 5, pp. 273-280 (2015). [13] al-alkawi h.j.m., ibtihal a. m., mamoon a. a. aljaafari," fatigue life study on 7075 aluminum alloy matrix / nanoparticles al2o3 reinforced composite" the iraqi journal for mechanical and materials engineering (2017). [14] hajizamani, hamidreza baharvandi" fabrication and studying the mechanical properties of a356 alloy reinforced with al2o3-10% vol. zro2 nanoparticles through stir casting" advances in materials physics and chemistry, vol. 1, pp. 26-30 (2011). [15] ali mazahery1 and mohsen ostadshabani, "investigation on mechanical properties of nano-al2o3-reinforced aluminum matrix composites "journal of composite materials 45(24) 2579–2586, (2011). [16] sharp p. k., barter s. a. and clark g., "localized life extension specification for the f/a-18. y470x19 pocket", melbourne: dsto-tn-0279, (2000). [17] abdizadeh h., baghchesara m.a., "investigation into mechanical properties and fracture behavior of a356 aluminum alloybased zro2 particle reinforced metal matrix composites" mechanics of composite materials, vol.49, no.5 (2013). )2019( 91، صفحة 1د، العد15دجلة الخوارزمي الهندسية المجلم حسين جاسم محمد العلكاوي 9 كبات باستخدام تقنية المر ٧٠٤٩تحسين الخصائص الميكانيكية و الكالل لسبيكة المنيوم النانوية *علي يوسف خنياب** عبدالجبار حسين علي**حسين جاسم محمد العلكاوي* *قسم هندسة الكهروميكانيكية/ الجامعة التكنولوجية ***دائرة البحث والتطوير/ وزارة التعليم العالي والبحث العلمي alalkawi2012@yahoo.com:البريد االلكتروني * al2024t4@gmail.com :البريد االلكتروني ** dr.abduljabarha@yahoo.com :البريد االلكتروني *** الخالصة 2zroباستخدام تقنية المركبات النانوية. تم اختيار ٧٠٤٩الهدف من العمل الحالي هو تحسين الخصائص الميكانيكية والكالل لسبائك األلومنيوم م استخدام ٪. ت٧و ٦، ٤، ٢بنسب وزنية مئوية مختلفة ٧٠٤٩نانومتر ، كجسيمات نانوية ، لتدعيم سبائك األلومنيوم ٤٠-٣٠قطر الحبوب بمتوسط . أظهرت هاوتصنيع لتصنيع المركبات النانوية بسبب العامل االقتصادي لتحسين مركبات المصفوفة المعدنية ) stir casting methodطريقة الصب ( ) مادة نانوية مدعمة تؤدي إلى تحسين الخواص الميكانيكية وان أفضل نسبة تحسين في الخواص 2zroالنتائج العملية أن إضافة أوكسيد الزركونيوم ( ٪) لإلجهاد الشد ٩٫٩٢٪) و ( 9.615σy٪) و ( ٧٫٧٦ σu٪ فكانت نسبة التحسين تساوي (٤كانت بـاستخدام نسبة وزنية aa ٧٠٤٩الميكانيكية لـ ظهرت النتائج أن متانة أ. كما 2zro٪ من ٧و ٦، ٢على التوالي من غيرها عند استخدام hbو للصالبة ysو لإلجهاد الخضوع utsاالقصى بدون aa ٧٠٤٩٪ من متانة الكالل لسبيكة االلمنيوم ٩٫٨٦أعلى بنسبة 2zro ٪ من الجسيمات النانوية ٤عند استخدام aa ٧٠٤٩الكالل لسبيكة ٪) عند اختبار بإجهادات مختلفة iflfدورة ، فضال عن معامل عمر الكالل ( ٨١٠ر حمل ثابت عند اضافة اي نسبة من اوكسيد الزركونيوم عند اختبا ٪ على التوالي.١٠٧و ٦٣و ١١٥و ٦٦ميكا باسكال تحسًنا بحدود ٢٥٠و ٣٠٠و ٣٥٠و ٤٠٠كانت <4d6963726f736f667420576f7264202d20dadeede120d5c8d1ed20e6e5c7e1c9312d3133> al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 14, no.2, june, (2018) p.p. 113 an investigation study of tool geometry in single point incremental forming (spif) and their effect on residual stresses using anova model aqeel sabree bedan* halah ali habeeb** *,**department of production engineering and metallurgy/ university of technology *email: 70061@uotechnology.edu.iq **email: eng_hala.ali60@yahoo.com (received 30 july 2017; accepted 5 november 2017) https://doi.org/10.22153/kej.2018.11.001 abstract incremental forming is a flexible sheet metal forming process which is performed by utilizing simple tools to locally deform a sheet of metal along a predefined tool path without using of dies. this work presents the single point incremental forming process for producing pyramid geometry and studies the effect of tool geometry, tool diameter, and spindle speed on the residual stresses. the residual stresses were measured by orionrks 6000 test measuring instrument. this instrument was used with four angles of (0º,15º,30º, and 45º) and the average value of residual stresses was determined, the value of the residual stress in the original blanks was (10.626 mpa). the x-ray diffraction technology was used to measure the residual stresses. the sheet material used was aluminum alloy (al1050) with thickness of (0.9 mm). the experimental tests in this work were done on the computer numerical control (cnc) vertical milling machine. the extracted results from the single point incremental forming process were analyzed using analysis of variance (anova) to predict the effect of forming parameters on the residual stresses. the optimum value of the residual stresses (55.024 mpa) was found when using the flat end with round corner tool and radius of (3 mm), wall angle of (55°) and a rotational speed of the tool of (800 rpm). the minimum value of the residual stresses (24.389mpa) was found when using hemispherical tool with diameter of (12 mm), wall angle of (45°) and a rotational speed of the tool of (800 rpm). keywords: anova, cnc milling machine, residual stresses, spif process, taguchi method. 1. introduction single point incremental forming (spif) process has been developed from sheet metal spinning, sheet metal shear moving and hammering with included cnc system to control the forming tool motion [1]. spif is a comparatively recent bed sheet forming process which enables forming of complicated shapes without specific dies utilizing only a single point tool and a standard three-axis cnc machine [2]. spif is a progressive and adaptable bed sheet metal-forming technology that uses layered manufacturing basis. that changes the part geometry data for a several parameters of 2d layers, and after that the plastic-local deformation is done layer-by-layer over the cnc machine motions of the simple forming aqeel sabree bedan al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 113 (2018) 2 tool to manufacture products with complicated shapes as demonstrated in figure (1) [3, 4]. fig. 1. representation of spif process [5]. 2. literature review many researchers studied the effect of spif process parameters on the residual stresses, but in this work will studying the effect of tool geometry on the residual stresses, some of related works are presented below: isaac jimenez and et al [6] presented the effect of the residual stresses along the aluminum products which produced by the spif process. the residual stresses on both outer and inner surfaces were measured by x-ray diffraction technique. the residual stresses measured were changed from tensile to compressive stresses. the data of experimental is indicated the residual stresses effects on the micro structural of the aluminum products. arshpreet singh and anupam agrawal [7] presented the comparison between traditional and ism bending/stretch forming in the residual stresses, deforming forces and geometrical contradiction. also, the influence of prior anisotropy in bending comparisons of the spring back and deforming forces contained. deforming forces was obtained in incremental sheet metal bending is less than obtained in traditional bending. residual stress generated over the product in incremental sheet metal bending was less in comparison of traditional bending process. the results showed that it is possible to rely on the incremental sheet metal forming process and commercialized as an alternative method to traditional deformation processes. d. m. neto and et al [8] presented the ismf process of aluminum alloy (aa7075) to produced simple truncated cone. the finite element model was utilized to analyze the stress and strain. the forming force, the thickness and an apportionment of plastic strain extracted from numerical model was validated with the results extracted from experimental. to be able to assess the through-thickness gradients effectively, the blank was modeled with solid fem. a negative mean stress under the tool was induced in the small contact area between the sheet and forming tool, which delay the occurrence of ductile fracture. a. s. bedan and et al [9] studied the effect of forming parameters (rotational speed, feed rate, and vertical depth) on residual stresses which induced in parts made of aluminum (al 1050) alloy. anova model used to know the contribution of rotational speed, feed rate, and vertical depth with respect to residual stresses was (63.7, 4.3, and 32) % respectively. aseel hamad abed and et al [10] presented the multilayer spif process and using top plate with three thicknesses (0.5, 0.7, and 0.9) mm, different types of lubrication used between two plates to predict the influence of these variables on residual stresses in bottom plate. the results explained an inversely relationship between the thickness of top plate and residual stresses. the minimum residual stresses were induced when using the graphite with grease lubricant between two plates. 3. residual stresses it is the stresses that stay in a body which is steady and in equilibrium with surroundings. the residual stresses rely on the interaction with external loads, they can effect on the interaction between the mechanical behavior and external loads. also they can effect on the lifetime and mechanical behavior of products by negative or positive method [11]. 3.1 x-ray diffraction this method used to calculate the residual stress depending on the measuring of angles at the maximum intensity of diffracted which happen whenever a crystalline specimen is submitting to x-rays. from these angles, bragg’s aqeel sabree bedan al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 113 (2018) 3 law is utilized to get inter planar spacing of the planes diffraction. when the residual stresses exist in the specimen, inter planar spacing will be various than that of unstressed state. the difference between two states is proportionate to the residual stress amount [12]. whenever a beam of x-rays monochromatic fails over the polycrystalline materials, the diffraction happens of those crystallites that are oriented to meet the bragg's law [13]: � � 2� sin � …(1) where: λ: the incident radiation wavelength. d: inter planar spacing. θ: the angle of the event beam makes with the diffracting plane (bragg angle). the acting single stress measure in some direction in the surface σ� . shows the strain along oblique line of isotropic solid according to elasticity theory (as shown in figure (2)) is [14]: ε∅� � ��� � �σ�cos�∅ � σ�sin�∅�sin�ψ� � � �σ� � σ�� …(2) use the strains to evaluate the stresses when evaluation the strains in conditions of spacing of inter planar and then it can be shown that σ∅ � � �������� � ! "#$"% "% & …(3) where: ε∅�: strain measured in the ∅ψ direction. v: poisson’s ratio. e: elastic modulus. σ�, σ�: principal stresses acting in the principal directions. ∅: the angle between the projection in the plane of normal diffracting plane and a fixed direction in that plane of the specimen. ψ : the angle between the normal diffracting plane and the normal of the specimen. d�: the spacing of inter planar of planes with angle ψ to the surface. d�: the spacing of inter planar of planes to the surface. fig. 2. residual stress measurement [14]. 4. experimental work 4.1 geometry construction of products the geometry of the products is pyramid shape with total depth of (35 mm) and with three different wall angle (45º, 50º, and 55º) as shown in figure (3). the cad model of the products illustrated in figure (3) was created by the following steps: • drawing the desired geometry of product by autocad program and save the drawing in the extension format (dwg) for example (file name.dwg). • opening the saved drawing in the solid work program and then save the drawing in the extension format (part) for example (file name.prt). • opening the file name with the extension format (part) in the cad/cam package (siemens ugs-nx9). aqeel sabree bedan al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 113 (2018) 4 fig. 3. the cad geometry and tool path of products. 4.2 sheet material the sheet material used in this work is aluminum alloy (al1050) with thickness of (0.9 mm). the initial dimensions of the blank were (225×225 mm). the chemical composition and mechanical properties are illustrated in the tables (1) and (2). table 1, chemical composition of the sheet material table 2, mechanical properties of the sheet material material yield stress (mpa) tensile strength (mpa) modulus of elasticity (gpa) elongation % poisson’s ratio al 1050 measured 71 86 72 4.1 0.33 astm standard 65-78 80-100 70-75 3.5-4.2 0.33 4.3 forming frame and forming tools forming frame was utilized to fixate the blank on the cnc milling machine table. forming frame is consisting of several components as shown in the figure (4). the forming tools that used in this work consist of three different geometries with different sizes to study the effect of these tools on the residual stresses. the first type was ball end with three diameters (8, 10, and 12) mm. the second type was hemispherical shape with three diameters (8, 10, and 12) mm. and the last type was flat end with round corner of different radius (3, 4, and 5) mm. figure (5) illustrates these tools. material al% si% fe% cu% mn% mg% cr% ni% zn% al 1050 measured 99.5 0.142 0.315 0.013 0.013 0.001 0.001 0.003 0.006 astm standard ≤99.5 ≤0.25 ≤0.4 ≤0.05 ≤0.05 ≤0.05 ≤0.03 ≤0.03 ≤0.05 aqeel sabree bedan al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 113 (2018) 5 fig. 4. assembly view of the forming frame. fig. 5. the tools used. 4.4 forming tests the spif processes of this work were performed at the university of technology/ training center and workshops, using 3-axis “ctek” cnc milling machine as shown in figure (6). the feed rate of (800 mm/min) and vertical depth of (1/3 mm) were used with tests. in this work, the used lubrication type is pennzoil (sae 5w-30). figure (7) is shown the products, which were produced by the ball end, hemispherical, and the flat with round corner tools. fig. 6. cnc milling machine utilized in experimental work. fig. 7. the products produced using three different geometries of tool. 5. residual stress test the test samples were prepared from the pyramid wall in circle shape with diameter of (30 mm) using die of wood identical to half of the shape of the product and this process performed on drilling machine as shown in the figure (8). the residual stress test was performed in the “ministry of construction and housingnational center for structural laboratories” by utilized orionrks 6000 test measuring instrument as shown in figure (9). the x-ray diffraction technology was used to measure the residual stress. aqeel sabree bedan al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 113 (2018) 6 fig. 8. preparing the test samples. fig. 9. residual stress measurement result. 6. design of experimental in this work, the taguchi’s (l9) orthogonal array was used for three types of tools. the processes parameters and levels for the ball end, hemispherical and the flat with round corner tools are illustrated in the tables (3-7). figure (10) presents the relationship between the results extracted from experimental work. table 3, forming parameters and their levels for ball end and hemispherical tools parameters units level 1 level 2 level 3 diameter mm 8 10 12 angle º 45 50 55 spindle speed rpm 0 400 800 table 4, forming parameters and their levels for the flat with round corner tools parameters units level 1 level 2 level 3 radius mm 3 4 5 angle º 45 50 55 spindle speed rpm 0 400 800 aqeel sabree bedan al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 113 (2018) 7 table 5, experimental layout using l9 orthogonal array and corresponding results for ball end tool. experimental no. process parameters response value machining time (min) diameter (mm) angle (º) spindle speed (rpm) residual stress(mpa) 1 1 1 1 38.556 32.09 2 1 2 2 42.023 34.16 3 1 3 3 44.857 36.26 4 2 1 2 36.797 31.01 5 2 2 3 32.922 32.58 6 2 3 1 39.66 34.59 7 3 1 3 28.605 29.54 8 3 2 1 37.98 31.41 9 3 3 2 32.962 33.32 table 6, experimental layout using l9 orthogonal array and corresponding results for hemispherical tool experimental no. process parameters response value machining time (min) diameter (mm) angle (º) spindle speed (rpm) residual stress(mpa) 1 1 1 1 36.427 32.09 2 1 2 2 39.274 34.16 3 1 3 3 41.722 36.26 4 2 1 2 35.79 31.01 5 2 2 3 30.452 32.58 6 2 3 1 37.666 34.59 7 3 1 3 24.389 29.54 8 3 2 1 34.966 31.41 9 3 3 2 30.508 33.32 table 7, experimental layout using l9 orthogonal array and corresponding results for the flat tool. experimental no. process parameters response value machining time (min) radius (mm) angle (º) spindle speed (rpm) residual stress(mpa) 1 1 1 1 49.104 28.11 2 1 2 2 53.972 30.25 3 1 3 3 55.024 32.46 4 2 1 2 47.078 28.36 5 2 2 3 43.148 30.44 6 2 3 1 51.796 32.58 7 3 1 3 39.813 29.02 8 3 2 1 48.261 31.04 9 3 3 2 43.802 33.09 aqeel sabree bedan al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 113 (2018) 8 (a) (b) (c) fig. 10. the results using: (a) ball end tool. (b) hemispherical tool. (c) flat with round corner tool. 7. optimization of forming parameters in this work, the taguchi approach is apply using mini tab package. the best parameters of forming are found according to signal to noise (s/n) ratio. depended on the kind of aqeel sabree bedan al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 113 (2018) 9 characteristics performance, taguchi categorizes the characteristics performance to three various types: the larger the better (lb), the nominal the better (nb), and the smaller the better (sb). for find the optimum forming parameters to give the best residual stresses, the smaller the better (sb) was used. equation (4) is used to determine the s/n ratio. the effect of each process parameters at different levels and the mean s/n ratio was illustrated in table (8). and the anova results for the experimental work is calculated and listed in table (9). ( ) � �10 log .�/∑ 12�/ 23� 4 …(4) where: i: no. of trial. y� : measured value of quality characteristic for ith trial condition. n: no. of repetitions. s: sum of degree of freedom for process parameters. 678 9:;ℎ:= >?@ab � c � 1 � d …(5) where: e: no. of experimental test. s: sum of dof for process parameters. the relationship between the process parameters and mean response (residual stresses) can be demonstrated in figure (11) and the interaction between the spif processes parameters and the residual stresses are showed in the figure (12). table 8, results for individual characteristic of mean response and s/n ratio ball end tool mean response s/n ratio diameter angle speed diameter angle speed level 1 41.81 34.65 38.73 -32.41 -30.72 -31.76 level 2 36.46 37.64 37.26 -31.21 -31.47 -31.38 level 3 33.18 39.16 35.46 -30.36 -31.79 -30.84 delta 8.63 4.51 3.27 2.05 1.07 0.92 rank 1 2 3 1 2 3 hemispherical tool mean response s/n ratio diameter angle speed diameter angle speed level 1 39.14 32.20 36.35 -31.84 -30.02 -31.21 level 2 34.64 34.90 35.19 -30.76 -30.81 -30.88 level 3 29.95 36.63 32.19 -29.44 -31.20 -29.94 delta 9.19 4.43 4.17 2.40 1.19 1.27 rank 1 2 3 1 3 2 flat with round corner tool mean response s/n ratio radius angle speed radius angle speed level 1 52.70 45.33 49.72 -34.43 -33.09 -33.93 level 2 47.34 48.46 48.28 -33.48 -33.67 -33.64 level 3 43.96 50.21 46.00 -32.83 -33.98 -33.17 delta 8.74 4.88 3.73 1.59 0.88 0.76 rank 1 2 3 1 2 3 table 9, anova results of the residual stresses ball end tool source of variance degree of freedom sum of squares (ss) variance (v) contribution on (p%) diameter 2 113.86 56.93 56.74 angle 2 31.55 15.78 15.72 speed 2 16.10 8.050 8.02 within group 2 39.16 19.58 19.52 total 8 200.67 100 hemispherical tool source of variance degree of freedom sum of squares (ss) variance (v) contribution on (p%) diameter 2 126.6 63.30 56.25 angle 2 29.90 14.95 13.28 aqeel sabree bedan al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 113 (2018) 10 speed 2 27.72 13.86 12.32 within group 2 40.85 20.425 18.15 total 8 225.07 100 flat with round corner tool source of variance degree of freedom sum of squares (ss) variance (v) contribution on (p%) radius 2 116.57 58.29 55.58 angle 2 36.61 18.31 17.46 speed 2 21.18 10.59 10.10 within group 2 35.38 17.69 16.86 total 8 209.74 100 fig. 11. relationship between process parameters and mean residual stresses. aqeel sabree bedan al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 113 (2018) 11 fig. 12. the interaction between the processes parameters and the residual stresses. 8. result and discussion the residual stresses are defined as the mechanical stresses and the best way to measure them is the experimental approach. there are two types of the residual stresses: tensile residual stresses and compressive residual stresses. a prefer type of the residual stresses is a compressive residual stresses because it leads to close the crack and increase the fatigue resistance for product. mostly, in spif processes the type of the residual stresses is tensile residual stresses. thus, the preferred value of the residual stresses is a low value. figure (11) showed that the residual stresses are inversely proportional to the tool diameter and rotational speed of the tool in all three cases for tools geometry used. while the relationship between the residual stresses and the wall angle of the pyramid is directly proportional. the residual stresses in the wall of the pyramid produced are decrease with increase of the tool diameter because increase in the contact area between the tool and sheet that leads to distribute the stresses and non-concentration in specific area. when the wall angle was increase, the thickness of the pyramid wall is decrease which leads to increase of the residual stresses in wall because concentration in small area. the effect of the rotational speed of the tool on the residual stresses in the product is same the effect of the tool diameter on it. when the rotational speed of the tool is zero, the residual stresses were at its highest values. and when the rotational speed is increases, the residual stresses are decrease because the heat was generated at high speed which leads to distribute the stresses in the wall. 9. conclusions al 1050 sheet were incremental formed under different forming tool geometry and their effects studies, the following conclusions were drawn from the study: 1-from the extracted results, the increase of the tool diameter and the rotational speed of the tool will reduce the residual stresses. while the increase in the wall angle will increase the residual stresses. 2-the optimum level of parameter for minimum the residual stresses was found with hemispherical tool at 3rd level of tool diameter parameter, 1stlevel of wall angle parameter and 3rd level of rotational speed parameter. therefore, these levels of parameters are giving the best values of residual stresses in spif processes of aluminum sheet (al1050). 3-the influence of process parameters on the residual stresses was indicated using analysis of variance (anova). the results indicated the contribution of tool diameter, wall angle and rotational speed with respect to the residual stresses is (56.74%, 15.72% and 8.02%) respectively when used ball end tool, (56.25%, 13.28% and 12.32%) respectively when used hemispherical tool, and (55.58%, 17.46% and 10.10%) respectively when used the flat with round corner tool. aqeel sabree bedan al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 113 (2018) 12 10. references [1] rattanachan k. and chungchoo ch., "formability in single point incremental forming of dome geometry", asian international journal of science and technology, production and manufacturing engineering, vol. 2, pages 57-63, 2009. [2] baden a. s., “optimization and prediction of process parameters in spif that affecting on surface quality using simulated annealing algorithm”, alkhwarizmi engineering journal, vol. 12, no. 4, pages 81-92, 2016. [3] zemin fu, jianhua mo, fei han, and pan gong, "tool path correction algorithm for single-point incremental forming of sheet metal", international journal of advanced manufacturing technology, vol. 64, pages1239–1248, 2013. [4] abed a. hamad, bedan a. s., and noori m. faeq, “study the effect of multilayer single point incremental forming on tool path mark for aa1050 bottom plates”, engineering and technology journal, vol. 35, part a., no. 6, 2017. [5] s. h. wu, ana reis, f.m. andrade pires, abel d. santos, and a. barata da rocha, "study of tool trajectory in incremental forming", advanced materials research, vols. 472-475, pages1586-1591, 2012. [6] jimenez i., lopez c., martinez-romero o., mares p., siller h. r., diabb j., sandovalrobles j. a., and elias-zuniga a., “investigation of residual stress distribution in single point incremental forming of aluminum parts by x-ray diffraction technique”, international journal of advanced manufacturing technology, vol. 91, pages 2571-2580, 2017. [7] singh a. and agrawa a., "comparison of deforming forces, residual stresses and geometrical accuracy of deformation machining with conventional bending and forming", journal of materials processing technology, vol. 234, pages 259–271, 2016. [8] neto d. m., martins j. m. p., oliveira m. c., menezes l. f., and alves j. l., "evaluation of strain and stress states in the single point incremental forming process", international journal of advanced manufacturing technology, london, 2015. [9] bedan a.s., mohammed s., and kamal m., “the effects of process parameters on residual stresses in single point incremental forming of a1050 aluminum using anova model”, engineering and technology journal, vol. 35, part a, no. 1, pages 41-48, 2017. [10] abed a. hamad, bedan a. s., and noori m. faeq, “study the effect of multilayer single point incremental forming on residual stresses for bottom plates”, alkhwarizmi engineering journal, vol. 13, no. 1, pages 99107, 2017. [11] crina r., eugen h., catalin t., and ion c., "the residual stress state generated by single point incremental forming of aluminum metal sheets", applied mechanics and materials, vol. 371, pages 148-152, 2013. [12] anderoglu osman, "residual stress measurement using x-raydiffraction", m. sc. thesis, department of mechanical engineering, texas a&m university, usa, 2004. [13] balasingh c. and singh a. k., " residual stresses and their measurements by x-ray diffraction methods", metals materials and processes, india, vol. 12, no. 2&3, pages 269-280, 2000. [14] m.e. fitzpatrick, a.t. fry, p. holdway, f.a. kandil, j. shackleton and l. suominen, “determination of residual stresses by x-ray diffraction”, issue 2, 2005. )2018( 1-13، صفحة 2د، العد14دجلة الخوارزمي الهندسية المجلم عقيل صبري بدن 13 االجهادات على وتأثيرها التزايدي في عملية التشكيل النقطيهندسية شكل العدة دراسة )anovaنموذج تحليل التباين ( باستخدامالمتبقية الناتجة *هاله علي حبيب* ل صبري بدن*عقي الجامعة التكنولوجية / قسم هندسة االنتاج والمعادن ،*** 70061@uotechnology.edu.iq :البريد االلكتروني* eng_hala.ali60@yahoo.com :البريد االاللكتروني** الخالصة لتشكيل الصفائح المعدنية باستخدام ادوات بسيطة والتي فيها تتعرض الصفيحة المعدنية لتشويه منتظم على مرنةعملية تزايديعملية التشكيل ال دتع شكل هرمي ودراسة تأثير إلنتاجطول مسار عدة محدد مسبقاً وبدون استخدام القوالب. يستعرض هذا العمل عملية التشكيل النقطي التزايدي المستخدمة . يعمل هذا الجهاز مع )orionrks 6000جهاز ( بوساطةدوران على االجهادات المتبقية. تم قياس االجهادات المتبقية شكل العدة، قطرها وسرعة ال ميكاياسكال). ١٠٫٦٢٦معدل االجهادات المتبقية، قيمة االجهادات المتبقية في الصفيحة االصلية ( ويؤخذدرجة) ٤٥و، ٣٠، ١٥زوايا هي (صفر، أربع ملم). وأجريت ٠٫٩) بسمك (al1050االشعة لقياس االجهادات المتبقية. الصفيحة المعدنية المستخدمة هي سبيكة االلمنيوم (تستخدم تقنية تشتت ا باستخدام التفريز العمودية المبرمجة. النتائج المستخرجة من عملية التشكيل النقطي التزايدي تم تحليله ماكينةاالختبارات العملية في هذا العمل على ميكاباسكال) عند ٥٥٫٠٢٤المتبقية ( لإلجهاداتتم ايجاد اعلى قيمة متغيرات عملية التشكيل على االجهادات المتبقية. تأثيرلمعرفة نموذج تحليل التباين ا دروة بالدقيقة). ٨٠٠والسرعة الدورانية للعدة ( درجة) ٥٥زاوية الجدار (، ملم) ٣بنصف قطر ( نهاية مسطحة مع تقوس في نهايتها اتاستخدام عدة ذ درجة) والسرعة ٤٥ملم)، زاوية الجدار ( ١٢) عند استخدام عدة شبه كروية قطرها (ميكاباسكال ٢٤٫٣٨٩( المتبقية لإلجهاداتاقل قيمة تم ايجاد و دروة بالدقيقة). ٨٠٠الدورانية للعدة ( (microsoft word 118-128\323\343\307) al-khwarizmi engineering journal,vol. 13, no. 1, p.p. design and implementation of a database department of computer email: (received 15 https://doi.org/10.22153/kej.2017.08.008 abstract the main aim of this paper are the design and implementation of a pharmaceutical inventory database management system. the system was implemented by creating a database containing information about the stored medicines in the inventory, customers making transactions with the pharmaceutical trading company (which owns the inventory), medical suppliers, employees, payments, etc. the database was connected to the main application using c sharp. the proposed system should help in manag inginventory operations w preparing sale and purchase invoices, generating reports, adding/updating customers and suppliers, tracking customer payments and checking expired medicines in order to be disposed. the system can be use workflow of sale and purchase operations and bring the advantages of having the most efficient control with minimal efforts. keywords: inventory database management system, invoicemedicine, , pharmaceutical. 1. introduction inventory management is one of the essential problems in almost every company. before computer age and integration, solutions were used as inventory management tools. if there is no automated system available, these solutions may cause a lot of paperwork usually lead to mistakes as the workload increases since it deals with more than hundreds of medications. the company needs to use a new technology to keep track of all its transactions and day-to-day operations to achieve its business goals by introducing a computer-based designing and implementing such a system is possible but there is preliminary work studying the operational environment and needs of the company, identifying the requirements, determining software tools, designing database and developing the user interface application (taner arsan, 2013). khwarizmi engineering journal,vol. 13, no. 1, p.p. 118128 (2017) mplementation of a pharmaceutical inventory atabase management system sama salam samaan computer engineering / university of technology email:samasamaan@yahoo.com 15 september 2015; accepted 4 august 2016) https://doi.org/10.22153/kej.2017.08.008 the main aim of this paper are the design and implementation of a pharmaceutical inventory database management system. the system was implemented by creating a database containing information about the stored medicines in the ansactions with the pharmaceutical trading company (which owns the inventory), medical suppliers, employees, payments, etc. the database was connected to the main application using c sharp. the proposed system should help in manag inginventory operations which include adding/updating employees’ information, preparing sale and purchase invoices, generating reports, adding/updating customers and suppliers, tracking customer payments and checking expired medicines in order to be disposed. the system can be used to facilitate smooth workflow of sale and purchase operations and bring the advantages of having the most efficient control with minimal : inventory database management system, invoicemedicine, , pharmaceutical. anagement is one of the problems in almost every company. computer age and integration, paper used as inventory management if there is no automated system available, may cause a lot of paperwork and usually lead to mistakes as the workload increases than hundreds of company needs to use a new technology to keep track of all its transactions and to achieve its business based system. implementing such a system is preliminary work such as studying the operational environment and needs requirements, ing system the user interface for the company, it is important to ensure that there is sufficient quantity of medications the needs of the customers. in addition, careful inventory management can increase the earnings. a badly managed inventory m more loss through medications expiring, accounting and inappropriately than a well-managed inventory (katie ingersoll, 2015). in order to provide an overview of previous work, some researchers presented by various authors are reviewed: • (toshio awaya et al., 2005) control system application named artima which allows inventory tasks to be faster and more efficient in real world. the medicines used in the hospital (where the system automatically fixed and arranged in sold and ordered from each wholesaler every day. system can search the quantities available expiration date of each drug in the purch delivery records. they find that the system al-khwarizmi engineering journal nventory the main aim of this paper are the design and implementation of a pharmaceutical inventory database management system. the system was implemented by creating a database containing information about the stored medicines in the ansactions with the pharmaceutical trading company (which owns the inventory), medical suppliers, employees, payments, etc. the database was connected to the main application using c sharp. the hich include adding/updating employees’ information, preparing sale and purchase invoices, generating reports, adding/updating customers and suppliers, tracking customer d to facilitate smooth workflow of sale and purchase operations and bring the advantages of having the most efficient control with minimal important to ensure that of medications to serve the needs of the customers. in addition, careful increase the company managed inventory may have more loss through medications expiring, incorrect ly recorded returns managed inventory (katie ingersoll, in order to provide an overview of previous presented by various , 2005), developed a system application named artima which to be faster and more rld. the medicines used in the is applied) were and arranged in sold-packages from each wholesaler every day. this quantities available and drug in the purchase and delivery records. they find that the system sama salam samaan al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 118128(2017) 119 functions are robust and useful in patient’s safety and cost containment. • (libby levison and hamish s f fraser, 2008) worked in a system that served as a case study of how to select and design a medical information system for use in a developing country. they found that all health care programs require a robust and reliable drug supply system. 2. objectives the proposed system should achieve the following goals: • add/update customers and medicine suppliers with their full information. • add/update system users and inventory employees. • add/update medicines with their scientific names, manufacturing company, manufacturing and expiry dates, batch numbers and the available quantities from each batch. • prepare sale and purchase invoices. • generate reports. • track customer payments. • detect expired medicines in order to be disposed. • manage returned medicines from customers in case of damage or overstock. 3. phases of database design and implementation for the pharmaceutical inventory database according to (ramez elmasri, 2015), the overall database design and implementation process is identified in six main phases: 1. requirements collection and analysis 2. conceptual database design 3. choice of a dbms 4. logical database design 5. physical database design 6. database system implementation and tuning. 3.1 requirement collection and analysis during this phase, the database designers meet potential system users to understand and document their data requirements. the result of this step is a briefly written set of users’ requirements (ramez elmasri, 2015). knowing the requirements and needs of the system is vital to its success. important inventory documents are collected and analyzed, including sale and purchase invoices, customers and suppliers’ records, employees' records, medicines’ records and customer payments. the collected requirements associated with this system include: 1. drugs have expiration dates after which they may no longer be used. after a specific amount of time, the chemical structures of medications may change to reduce their strength or change it into a completely different product. medications must be dragged off the shelf when this date approaches, because it is unsafe to distribute drugs after the expiration date has passed. it is important to consider expiration dates when ordering medications. 2. when preparing a sell invoice, it is important to use older medications before newer medications to ensure that products with shorter expiration dates are used before those that will last longer and minimize the number of expiring products. 3. outdated products should be pulled off of the shelves at steady intervals to reduce the chance of expired medications getting to a patient. 4. pharmacies can return medications that has been ordered in surplus or is moving slowly off of the shelves. in general, if a package has been unlocked or damaged and does not expire for at least 12 months, a company can accept the medication for return. 5. if any medications are received damaged or expired, or if the pharmacy accidentally ordered a product it does not need, it may be desirable for return to the company. 6. after the order is received and put away, bills must be paid according to the accounting steps of the company. they often need to be entered into the computer system on the same day they are received or as soon as possible after receipt. 7. the manufacturer’s recommendations should be followed when storing medications. many medications are able to be stored at room temperature 20-22 °c. drugs should not be stored above or below this temperature range unless authorized by the manufacturer. 8. some drugs require refrigeration to preserve the stability of the medication. in general, refrigerated medications need to be stored between 2 8 °c. 9. because frozen drugs are especially vulnerable to damage, care must be taken when handling these products. frozen medications should be stored below -15 °c. there are very few medications that require storage in the freezer; those that do include the chickenpox and some premixed iv medications in the hospital setting that may be dissolved prior to use. sama salam samaan al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 118128(2017) 120 10. chemotherapy medications are considered hazardous substances. all employees who could reach these products be aware of the risks to which they could be exposed (katie ingersoll, 2015). 3.2 conceptual database design the next phase is to create a conceptual schema for the database, using a high-level conceptual data model. the conceptual schema is a description of the data requirements of the users. because these concepts do not include implementation details, they are usually easier to understand and can be used to communicate with nontechnical users. the conceptual schema can also be used as a reference to ensure that all requirements are met and do not conflict. the entity-relationship (er) model was proposed by peter chen in 1976 for conceptual design. in some ways, class diagrams can be considered as an alternative notation to er diagrams (ramez elmasri, 2015). in this project, the conceptual modeling is performed using uml (unified modeling language) class diagram notation. fig (1) shows the conceptual schema diagram that is created for the pharmaceutical inventory database. fig .1. the designed pharmaceutical inventory conceptual schema in uml class diagram notation. sama salam samaan al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 3.3 choice of a dbms in this project, relational database management system is chosen. many of the databases in widespread use are based on the database model. rdbms is a common choice for the storage of information in new databases used for financial records, manufacturing and logistical information, personnel data, and other applications (thomas m. connolly, 2014 commercial rdbms that is chosen is microsoft sql server. fig. 2. result of mapping the pharmaceutical schema. 3.5 physical design in this phase the internal storage structures, file organizations, indexes, access paths, and physical design parameters for the database files are khwarizmi engineering journal, vol. 13, no. 1, p.p. 118 121 ase management any of the databases in widespread use are based on the relational a common choice for the storage of information in new databases used for financial records, manufacturing and logistical personnel data, and other thomas m. connolly, 2014). the commercial rdbms that is chosen is microsoft 3.4 logical database design during this phase, the conceptual schema (resulted from phase 2) is mapped from the high level data model into the data model of the chosen dbms. the resulted logical data model is validated to check structural correctness and support for the required transactions. steps of an algorithm described in ( elmasri, 2015) are followed for er mapping. the resulted pharmaceutical inventory relational database schema is shown harmaceutical inventory uml schema into a relational the internal storage structures, file organizations, indexes, access paths, and physical design parameters for the database files are specified. in parallel with these activities, application programs are designed and implemented as database transactions corresponding to the high level transaction specifications (thomas m. connolly, 2014 118128(2017) logical database design during this phase, the conceptual schema is mapped from the highlevel data model into the data model of the chosen logical data model is validated to check structural correctness and support for the required transactions. a number of of an algorithm described in (ramez followed for er-to-relational pharmaceutical inventory relational database schema is shown in fig (2). relational (logical) database specified. in parallel with these activities, application programs are designed and implemented as database transactions corresponding to the high level transaction thomas m. connolly, 2014). sama salam samaan al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 118128(2017) 122 3.6 database system implementation and tuning during this phase, the database and application programs are implemented, tested, and finally deployed for service. various transactions and applications are tested separately and then in conjunction with each other. this typically reveals opportunities for physical design changes and reorganization, an activity referred to as database tuning which continues for the life cycle of a database as long as the database and applications keep evolving and performance problems are detected [v] every system user (who is eligible to use and access the proposed system) has his/her workstation. each workstation is connected to a switch. the database server is connected to that switch. each user can access the system from the application installed in his/her local workstation. the system can only be accessed from the local network. the front end of the system is designed using c sharp. the backend is developed using ms sql server. the system will be applied in a lan as in fig (3). in a client-server scenario, we have the sql server installed on a server machine. clients will be the computers accessing that server using the implemented software. each client will provide a way of making a connection to the server instance running on the server. we will need the ip address or the server name along with sql server instance name. they both combined to form the host name: data source = servername\ instancename for each computer that will run our application, we should install the executable version on each computer. the system will be password-protected. each user will be assigned system access privileges appropriate to its role. the system will be disconnected from world wide web to prevent all possible hacking and cracking from the internet. the system will have the following roles: 1. normal user role the normal user can do a number of tasks like preparing sale and/or purchase invoices, print reports, search for a drug and its quantity available in the inventory, add new customer and/or supplier, check payment records and check drugs that are expired in order to dispose it or drugs that will be expired after three, six or nine months in order to be sold before it became out of date. 2. administrator role the admin can add new user to the system and give him/her a user name and password to access the system, edit employees’ salaries, in addition to all the activities that the normal user can do as described above. fig. 3. the lan where the proposed system is applied. • once the user runs the application for the first time, the login form shown in fig (4) is displayed so that the user should enter his/her credentials (the username and password), if the entered information is correct; the user will login to the system and the main form shown in fig (5) is showed. there are two types of users, normal or (regular) user and admin user. • when the user selects sale invoice tile, the window shown in fig (6) is presented. • using this form, the user can prepare a new sale invoice. notice the following: • the invoice number is generated automatically. • the pharmacy names and product or drug names are loaded from the database. • when the user selects a particular drug and its manufacturer (since different manufacturers, in different countries can produce the same drug), the unit price, the storage location and the available quantity in the inventory are displayed. the user should enter the required quantity and press “add to invoice”. • there are two types of payments, cash and deposit. as shown in the above figure, an invoice (no. 4) prepared in 5/8/2016, with 3 items: sama salam samaan al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 118128(2017) 123 1. betazinc 100 ml susp., required quantity 50, unit price 11 $. 2. fixef 400 mg 5 tab., required quantity 30, unit price 4.125 $. 3. amoklavin 457 mg susp. 70 ml., required quantity 60, unit price 4 $. 4. and so on. as example, if the inventory has 350 item from (amoklavin 457 mg susp. 70 ml.), but in two different batches, the 1st batch with expiry date 1/2017 (quantity = 50) and the second batch with expiry date 1/2018 (quantity = 300). the application will first select the first batch; if the required quantity is larger than the available quantity in the first batch, it should select the remaining quantity from the second batch. when the user clicks print invoice button, a report is generated which can be viewed and saved as a pdf file or excel sheet as shown in fig (7). when the user clicks purchase invoice tile, the form shown in fig (8) is displayed. here the user should enter the drug’s batch number, unit price, purchased quantity and manufacturing and expiry dates for each drug purchased from any supplier. when the user selects products tile, a form shown in fig (9) is displayed. as example, drug named “amoklavin 1000 mg 10 tab.”, manufactured by deva company, is stored in the inventory as two batches, the 1st batch with quantity equals 200 and the 2nd batch with quantity equals 90. there are two batches because there have different manufacturing and expiry dates. when the user clicks “add product”, a form as shown in fig (10) is displayed. when the user selects employee tile, a form as shown in fig (11) is displayed. when the user selects expired products tile, a form as shown in fig (12) is displayed. there are a number of options, first show already expired drugs, the second one show drugs expired after one month, the third one show drugs expired after two months and so one. when the user clicks customer payment tile, a form as shown in fig (13) is displayed. when the user selects restored drugs tile, a form as shown in fig (14) is displayed. a pharmacy can restore drugs purchased from the inventory in two cases. first, when the drug is received with damages and second when the drug is no longer in use (over stock) but not expired. the inventory makes a discount for each returned batch. fig. 4. user login form. fig. 5. the main form. sama salam samaan al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 118128(2017) 124 fig.6. sale invoice. fig. 7. sale invoice report. fig.8. purchase invoice form. sama salam samaan al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 118128(2017) 125 fig.9. show products form. fig. 10. add new product form. fig. 11. add new employee form. sama salam samaan al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 118128(2017) 126 fig. 12. expired drugs form. fig. 13. customer payment form. fig. 14. restore drugs form. sama salam samaan al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 118128(2017) 127 5. conclusions in this paper, a number of necessities for an inventory management system for pharmaceutical industries are achieved: 1. provide full information about each stored drug, its quantity, manufacturing company, batch number, manufacturing and expiry dates, storage location, storing temperature and dangerous level. 2. older drugs are used before newer drugs when preparing a sell invoice, to ensure that products with shorter expiration dates are used before those that will last longer and minimize the number of expiring products. 3. medications are pulled off the shelf when their expiry date approaches. the system provides information about drugs that are expired or will be expired after a certain period of time. 4. track customer payments. 5. restore drugs from customers that are received damaged or over stocked. 6. in addition to all the capabilities that the system user has, the administrator can: 7. add new employees (working in the inventory) and system users (who have the necessary credentials to access the system). 8. update employees’ information (e.g. salary, password). 6. future work 1. many medications have barcodes on their packaging to allow for easy identification of the product in a computer system. using barcode reader, medications’ barcodes can be stored for easy identification. 2. statistical reports can be developed to display the purchasing history of the most sold medications to appropriately manage the stored levels of these products. 3. the system can be developed to work on portable devices. 7. references [1] taner arsan, emrah baskan, emrah ar, zeki bozkus, “a software architecture for inventory management system”, 2013. [2] katie ingersoll,” inventory management for the pharmacy technician”, 2015. [3] toshio awaya, ko-ichi ohtaki, takehiro yamada, kuniko yamamoto, toshiyuki miyoshi, yu-ichi itagaki, yoshikazu tasaki, nobumasa hayase, kazuo matsubara, “automation in drug inventory management saves personnel time and budget”, yakugaku zasshi 125 (5) 427-432 (2005), the pharmaceutical society of japan. [4] libby levison, hamish s f fraser, “requirements for an open-source pharmacy dispensing and stores management softw/are application for developing countries”, 2008. [5] ramez elmasri and shamkant b. navathe, "fundamentals of database systems", 7th edition, book, pearson, 2015. [6] thomas m. connolly and carolyn e. begg, “database systems a practical approach to design, implementation, and management”, 6th edition, book, pearson, 2014. ���� 1، ا���د�13� � ا���ارزم� ا������� ا��� م ��� ����ن ��م ،2017( 128-118( 128 م$,+ ادو*� (دارة%)��' و%���$ �#�م "�!�ة �����ت ��� ��م ����ن ا����� ا��������� /�� ھ� � ا�����ب ا�����و����� samasamaan@yahoo.com: ا� �� ا��� � *��0 ھ ا ا��'�م .و*��0 ه ا�, ف ا���س �, ا ا��)+ ھ� *()� �'�م ��% ة $����ت �دارة � �� ادو*1� ة $����ت *�5)3 �����4ت %3 ط�%�� 14� *���>ت �; ا�) ��، ا�)�,:�3، ا�)�ظ3�0، ا� �7%�ت و��6ھ�,� � 3� ة ا������ت * ر$a . *?@ ا�دو� ا�)���7ة �7 ا�)?:ن، �����4ت ا�:$�=3 ا� %�� b�=ا�� c�������$ d� ام ?���$c sharp .���g �����4ت ا�)�,:�3 ان ا��'�م ا�)��fح �7 ادارة %)��4ت ا�)?:ن وا��� *�5)3 ا7�h او *�%���i ان . �m ��dض ا*>7,�وا�)�ظ3�0 وا�:$�=3 وا�دو� ، ا% اد �7ا*�� ا���; وا��kاء وط��% ا���fر��، ���$� د�7%�ت ا�:$�=3 وا���1f �3 ا�دو� ���,� ا�(> +(% n�$ ��7��� م ?���� و��� ��)��4ت ا���; وا��kاء وادارة ا��)+ $��0ءة $��+ �, �)�3ھ ا ا��'�م ����. 8288 al-khwarizmi engineering journal,vol. 11, no. 4, p.p. the influence of design and technological parameters on the maf saad kariem **department of (received abstract experimental work from magnetic abrasive finishing (maf) tests and number of cycle which are formed the cutting speed, working gap, and finishing in maf process. this research has made to study the effect of design and technological parameters on the surface roughness (ra), micro hardness (hv) and material removal (mr planned using response surface methodology according to the analysis of variance and instruction curves indicate some significant. the surface roughness ra for steel, x2 has mildly significant, while showed that roughness of workpiece decreased from 0.3 to 0.15 keywords: design and technological parameters software. 1. introduction non-traditional maf process were method for technology of machining maf was removed microchips, in order to get the higher mechanical properties surfaces, process has been used to produce microrelief layer. the specialty of maf capability to control the flexibility ferromagnetic powder sealing by magnetic field one can control the density and rigidity of the magnetic brush, that help to topography of magnetic flux in the working gap this specialty of maf process was finishing methods. maf process was simplicity; improved the quality of roughness (ra) above 50 %. maf process, gives good economic and ecological environment [1-6], by this method can finished different surfaces like cylindrical, flat, bolt complex shapes, for ferromagnetic materials [ khwarizmi engineering journal,vol. 11, no. 4, p.p. 8288 (2015) design and technological parameters on the maf process saad kariem shather* shakir m. mousa department of production engineering/ university of technology **technical institute/ musayab *email: drengsaad_k_sh@yahoo.com **email: shakir.aljabiri_89@yahoo.com (received 7 april 2015 ; accepted 16 june 2015) from magnetic abrasive finishing (maf) tests was carried out design parameters are formed the shape of electromagnetic pole), and technological parameters finishing time) all have an influence on the mechanical properties of the surface layer has made to study the effect of design and technological parameters on the surface and material removal (mr) in working zone. a set of experimental planned using response surface methodology according to taguchi matrix (36) with three levels and instruction curves indicate some significant. x1; x4; x6 have a significant effect on 2 has mildly significant, while x3 and x5 have insignificant effect. creased from 0.3 to 0.15 µm that means improved the roughness to technological parameters, micro-hardness, surface roughness, material of removal were advanced technology of machining, the ability of in order to get the surfaces, this to produce microrelief process was flexibility of tool, ferromagnetic powder sealing by magnetic field, one can control the density and rigidity of the change the in the working gap. differs at other was universal, the quality of surface . maf effective and ecological this method can finished like cylindrical, flat, bolt, and materials [4]. this work aims to study and technological parameters surface mr, by using experimental finding the mathematical mo minitab software. 2. experimental procedure an electromagnetic inductor manufactured using for the inductor was a steel rod wrapped around a coil of wires, magnetic force working gap, between pole gap was filled with powder and the applied by (dc) power supply al-khwarizmi engineering journal (2015) design and technological parameters on the maf mousa** university of technology esign parameters (amplitude, ), and technological parameters (current, all have an influence on the mechanical properties of the surface layer has made to study the effect of design and technological parameters on the surface . a set of experimental tests has been with three levels and six factors. have a significant effect on 5 have insignificant effect. the results the roughness to 100%. material of removal, minitab this work aims to study the influence of design parameters on the quality of experimental method then finding the mathematical models with the rocedure an electromagnetic inductor has designed and finishing flat surfaces. a steel rod wrapped around a of wires, magnetic force was generate on the , between pole and workpiece, the gap was filled with powder and the current was supply. see figure 1. saad kariem shather al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 8288(2015) 83 fig. 1. electromagnetic inductor. the characteristic of inductor are the following: the materials of the core was low carbon steel c15 the diameter of copper wire was 0.9mm the number of turns was n=3000 turns the material of pole from low carbon steel the abrasive powder was (65%) oxide of the iron with (35%) tungsten carbide. the doze of powder was (5 cm3). there are six input parameters have been choose, the values of parameters and their three levels were illustrate in table (1). the input parameters were applied according to the taguchi matrix (l27) and the output was shown in table (2). three observed value of change in surface roughness (ra), weight (mr),and micro-hardness (hv), were examined, for ferromagnetic material as steel 304, before and after polishing measured the ra, hv and, w then finding the value ∆ra, ∆hv, mr were averaged. the surface roughness ra measured by tester srt-6210surface roughness, time tester was used to measuring hv, the mr measured through measuring the weight of the workpiece before and after process (∆w) using the delicate balance. for steel material, 27 tests were applied. the last step adjusts the value of the six input parameters according to taguchi matrix, and fixed the workpiece on the table of the milling machine, then filled the working gap with powder (5cm3). table 1, input parameters values. input levels symbol level 1 level 2 level 3 amplitude of pole geometry (mm) x1 4 8 12 number of cycles of pole geometry x2 2 5 8 finishing time (min) x3 5 10 15 cutting velocity (rpm) x4 175 580 970 current (amp) x5 1.0 1.5 2.0 working gap (mm) x6 1.0 2.0 3.0 3. results and discussion the criterion outputs, ∆ra, ∆hv, and mr are dependent variable in regression models, while the predictor’s factors were the amplitude of pole geometry, number of cycles of pole geometry, finishing time, and cutting velocity, current and working gap. table (2) shows the result of experiment for ferromagnetic material. saad kariem shather al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 8288(2015) 84 table 2, results of experiments for steel 304 and distribution parameters according to taguchi matrix l27. № x1 x2 x3 x4 x5 x6 ∆ra, µm ∆w mr ∆hv 1 1 4 1 2 1 5 1 175 1 1 1 1 0.292 0.001 10.5 2 1 4 1 2 1 5 1 175 2 1.5 2 2 0.278 0.0012 9 3 1 4 1 2 1 5 1 175 3 2 3 3 0.383 0.3036 8.6 4 1 4 2 5 2 10 2 580 1 1 1 1 0.387 0.0024 6.6 5 1 4 2 5 2 10 2 580 2 1.5 2 2 0.466 0.0016 10.8 6 1 4 2 5 2 10 2 580 3 2 2 2 0.233 0.0041 7.5 7 1 4 3 8 3 15 3 970 1 1 1 1 0.352 0.0026 11.5 8 1 4 3 8 3 15 3 970 2 1.5 2 2 0.377 0.002 8.7 9 1 4 3 8 3 15 3 970 3 2 3 3 0.044 0.0068 8 10 2 8 1 2 2 10 3 970 1 1 2 2 0.099 0.0098 25 11 2 8 1 2 2 10 3 970 2 1.5 3 3 0.108 0.0044 11.6 12 2 8 1 2 2 10 3 970 3 2 1 1 0.064 0.0084 9.6 13 2 8 2 5 3 15 1 175 1 1 2 2 0.118 0.0011 21.1 14 2 8 2 5 3 15 1 175 2 1.5 3 3 0.21 0.0051 22.8 15 2 8 2 5 3 15 1 175 3 2 1 1 0.672 0.0094 13.5 16 2 8 3 8 1 5 2 580 1 1 2 2 0.241 0.0013 20.7 17 2 8 3 8 1 5 2 580 2 1.5 3 3 0.225 0.0014 3.8 18 2 8 3 8 1 5 2 580 3 2 1 1 0.378 0.0063 7.7 19 3 12 1 2 3 15 2 580 1 1 3 3 0.028 0.002 15.5 20 3 12 1 2 3 15 2 580 2 1.5 1 1 0.164 0.0425 17.4 21 3 12 1 2 3 15 2 580 3 2 2 2 0.111 0.0023 26.7 22 3 12 2 5 1 5 3 970 1 1 3 3 0.102 0.0079 25.9 23 3 12 2 5 1 5 3 970 2 1.5 1 1 0.068 0.0027 8.3 24 3 12 2 5 1 5 3 970 3 2 2 2 0.038 0.0023 5.8 25 3 12 3 8 2 10 1 175 1 1 3 3 0.14 0.0017 16.8 26 3 12 3 8 2 10 1 175 2 1.5 1 1 0.393 0.0099 11.8 27 3 12 3 8 2 10 1 175 3 2 2 2 0.287 0.0055 21.7 3.1. regression model for surface roughness (ra for steel 304) versus x1; x2; x3; x4; x5; x6 by using minitab 16 statistical software, finding the mathematical statistical regression models for maf process between the surface roughness and all six parameters are represented bellow. ra st. = 0.494 0.0196 x1 + 0.0169 x2 + 0.00079 x3 0.000212 x4 + 0.0423 x5 0.0707 x6 …(1) the regression analysis of variance (anova) on to surface finish ∆ra for steel 304. the results of analysis were show in table (3). table 3, result of anova. predictor coefficient p effect inductor x1 -0.019587 0.008 significant effect (p<0.05) x2 0.016852 0.072 mildly significant effect (p<0.1) x3 0.000789 0.884 insignificant effect (p> 0.1) x4 -0.000213 0.005 significant effect (p<0.05) x5 0.04225 0.438 insignificant effect (p> 0.1) x6 0.07073 0.018 significant effect (p<0.05) analysis of variance for regression also show: r-sq = 60.5% f =5.11 p =0.003 the r-sq showed that 60.5% of the observed variable in surface roughness for steel was independent variable. fvalue was high; p-value for regression equation was significant effect. the coefficients (of output parameters) for regression are listed in the table (3). for these coefficients, multiple linear regressions (mathematical statistical model) for surface roughness with steel materials could be expressed equation (1). saad kariem shather al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 8288(2015) 85 3.1.1. the effects of amplitude, velocity of pole, and working gap on the surface roughness ∆ra for steel 304. however for the six input factors, all coefficient of the linear regression equation 1, analysis of variance and instruction curves figure 2 indicate some significant. x1; x4; x6 have a significant effect on the surface roughness ∆ra st., curves shows that if the x1; x4; x6 increases, the surface roughness ∆ra for steel decreases. the influence of amplitude (x1) that has a significant effect on surface roughness as follow: the increases in amplitude from 4 to 12 mm lead to decreases in the ∆ra from 0.3 to 0.15 µm improved to 30%. from all six parameters. this figure also shows that an increases in cutting velocity x4 from 175 to 970 rpm lead to reduce in the ∆ra st. from 0.3 to 0. 15 µm. in the same way decrease in working gap x6 from 1 to 3 mm lead to reduce in the ∆ra st. from 0.3 to 0.15 µm improved the surface roughness to 32%. working gap x6 improving the surface roughness to 24%, 3.1.2. the effect of number of cycles on the surface roughness ∆ra . the number of cycles x2 has mildly significant effect on the ∆ra, compared with amplitude, cutting velocity and working gap. figure 2 shows if the number of cycles increases from 2 to 9 the ∆ra st. increases from 0.15 to 0.3 µm that means improved in the surface roughness. x2 improve surface roughness to 11%, current improved the surface roughness to 3%, while x3 finishing time insignificant. fig. 2. main effects of process parameters on the surface roughness ∆ra st. 3.2. regression model for material removal mr (steel 304) versus x1; x2; x3; x4; x5; x6 by using minitab 16 statistical software, finding the mathematical statistical regression models for maf process between removal rate and all six parameters are represented in equation 2. mr st. = 0.0387 0.00370 x1 0.00625 x2 0.00282 x3 0.000041 x4 + 0.0374 x5 + 0.0175 x6 …(2) the regression analysis of variance (anova) on to removal rate for steel 304 the results of analysis were show in table (4). table 4, result of anova. predictor coefficient p x1 -0.003695 0.259 x2 -0.006254 0.156 x3 -0.002821 0.280 x4 -0.000041 0.215 x5 0.03738 0.158 x6 0.01754 0.197 analysis of variance for regression also show: r-sq = 33.2% f-value = 1.66 p = 0.18 this regression has insignificant effect because (p> 0.1) and r-sq denotes an observation with a large standardized residual, f-value was low. see figure 3. fig. 3. main effects of process parameters on the mr st. saad kariem shather al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 8288(2015) 86 3.3. regression model for micro-hardness hv (steel 304) versus x1; x2; x3; x4; x5; x6 . by using minitab 16 statistical software, finding the mathematical statistical regression models for maf process between the microhardness hv and all six parameters are represented bellow. hv st. = 9.46 + 0.935 x1 0.430 x2 + 0.499 x3 0.00300 x4 4.79 x5 +1.39 x6 …(3) the regression analysis of variance (anova) on to micro-hardness hv for steel 304. the results of analysis were show in table (5). table 5, result of anova. predictor coefficient p effect inductor x1 0.9349 0.010 significant effect (p<0.05) x2 -0.4296 0.337 insignificant effect (p> 0.1) x3 0.4989 0.072 mildly significant effect (p<0.1) x4 -0.003003 0.373 insignificant effect (p> 0.1) x5 -4.790 0.083 mildly significant effect (p<0.1) x6 1.388 0.318 insignificant effect (p> 0.1) analysis of variance for regression also shows: r-sq = 50.1% f = 3.08 p = 0.026 significant effect in the process maf respect to microhardness. the r-sq showed that 50.1% of the observed variable in micro-hardness for steel was independent variable. fvalue was high; p-value for regression equation was significant effect. the coefficients (of output parameters) for regression are listed in the column above. for these coefficients multiple linear regressions (mathematical statistical model) for surface roughness with steel materials could be expressed, see equation 3. 3.3.1. the effects of amplitude on the micro-hardness ∆hv st the effect of amplitude x1 has a significant effect on the ∆hv st. compared with other parameters, figure 4 show if the amplitude increases from 4 to 12 the ∆hv st. increases from 8 to 17 mpa, and improved in the surface quality about 42%. 3.3.2. the effects of finishing time and current on the micro-hardness ∆hv st the effect of finishing time x3 and current x5 have a mildly significant effect on the microhardness hv compared with amplitude, figure 4 shows, if the finishing time increases from 5 to 15 the ∆hv st. increases from 8 to 17 mpa, and improving in the surface quality about 20%. if the current increases from1to 2 amp the microhardness ∆hv decreases from 17 to 12 mpa and improved the quality to 18%. 3.3.3. the effects of number of cycle, cutting velocity and working gap on the micro-hardness ∆hv st the effect of number of cycle x2 and cutting velocity x4 have insignificant effect on the microhardness because the p-value was p> 0. 1. improving the quality about 5%. fig. 4. main effects of process parameters on the micro-hardness ∆hv for steel. saad kariem shather al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 8288(2015) 87 4. conclusions this study shows the influence of design and technological parameters, amplitude of pole geometry, number of cycles of pole geometry, finishing time, cutting velocity, current and working gap on the maf output process. generate regression models for surface roughness, micro-hardness and material removal, and by using regression analysis of variance (anova), the influence on the maf process as follow: the parameter x1, (the amplitude of pole geometry) has significant effect on the surface roughness ra, which improved the surface roughness about 30%. , this parameter x1 has significant effect on the micro-hardness about 42%. while this parameter x1 has insignificant effect on the mrr. the effect of another parameter (x2, x3, x4, x5, and x6) on the properties of the surface layer (roughness, micro-hardness, and removal rate). were puts in table 6. table 6, conclusions. parameters influence on ∆ra improving ∆ra% influence on ∆hv improving ∆hv% influence on mr x1 significant 30 significant 42 insignificant x2 mild significant 11 insignificant 6 insignificant x3 insignificant 0.0 mild significant 20 insignificant x4 significant 32 in significant 5 insignificant x5 insignificant 3 mild significant 18 insignificant x6 significant 24 insignificant 9 insignificant total 100% total 100% 5. references [1] h. kumar, s. singh, and p. kumar, “magnetic abrasive finishinga review”, international journal of engineering research & technology (ijert), vo. l, issue 3, march 2013. [2] jain vk, “ advanced machining processes”. allied publishers, delhi, 2002. [3] yamaguchi h, and sato t, “ polishing and magnetic fieldassisted finishing”, intelligent energy field manufacturing interdisciplinary process innovations, 2012. [4] yu. m. baron, “ technology of abrasive machining in a magnetic field”, mashinostroenie, leningrad 1975. [5] n. k. jain, v.k. jain, and s. jha, “parametric optimization of advanced fine finishing processes”, international journal of advanced manufacturing technology, vol. 34, issue 11-12, pp 1191-1213, november 2007. [6] yin. s. and shinmura t, “ study of magnetic fieldassisted machining process for ferromagnetic metallic materials”, journal of japan soc. abrasive technology, vol. 46, issue 3, pp. 141145, 2002. )2015( 8288، ;:9/ 4، ا-'&د11&+*/ ا-56ارز(3 ا-12&)0/ ا-,+*()'& %$#" ! ر 88 �ت ا �� �ط�������ر ا �وا�ل ا ������� وا �� و و��� ��� �� ����� ا ��ط�ب ��� ��ر� �� *��� &%$#د �!�!�** ا-+=('/ ا-@de //0f5-51g" ھ1&)/ اab@=ج وا-,'=دن* ا-,i0d ا-,'2& ا-@de /31h" اab@=ج** *3aو$@g-bا &#$j-ا :drengsaad_k_sh@yahoo.com **3aو$@g-bا &#$j-ا: shakir.aljabiri_89@yahoo.com ا+*()' 3d01=طl,-ا m91-=n i0op@-0/ -',*0/ ا*,q رب=+s 0:1s "s )maf (و t*q uv0,0/ا,w@-0$ات اl@,)/'d-ا، ioh-ا yg! m*g! 3@-د ا-&ورات ا&q %y ھ ه ا-'5ا(t*q $0abs =2y ا-56اص ا-,hjo*_0g0a=g0/ ) ز(^ ا-@y0lp ا-21=[3 و ا-:+5هو )$q/ ا-oh]وا-@0=ر(/ و% -z ا-,@0l$ات ا-@0f5-51g )1=طl3d0ا-, /09od-0/ ا-ا*,q 3v /-5lp,)maf.( &,q0وf5-51g@-0,0/ وا,w@-0$ات اl@,-0$ اabs /(درا t-ا c9j-ھ ا ا/ dod-ا /a5pe t*q)ra( ،-وا/h0e&-ده اfw )hv (وأزا-/ ا-,'&ن )mr (y,'-ا /ho1) 3v .$o-6&ام ا@(bn رب=+@*i0o6@-وا j9:-ا "s &eا[و dod-ا /n=+@(21+0/ ا) yk) /0]=wlbا u)rsm( bhjوط 3f5%=s /v5:w,)36 (تf)=')او y)5اq /@(5#=ت و@d) /afkn ا-@+=رب m,,; .t-0$اps "0*'@-و(0191=ت ا ^#=j@-ا y0*9s 5د ا!=راتfوx1,x4,x6 /09od-ا /a5p6-ا t*q $0j%$0abs =25نg#)ra∆ (/-5lp,-ن ا&',-. x2 #o(5@) =0$ھabs 5نg= ، =,10n# 5نg$0a=sx3,x5 f0mn . /0]=21-ا o]b@1-وأظ2$ت ا ^) m*e /-5lp,*dod-ا /a5pe 0.3ان t-0.15ا dj;أ ^d9@-و(@$ وھ ا #'31 ان ا$g#=) 100%. <4d6963726f736f667420576f7264202d2036362d3733e3d5d8ddec20e6ceedd1edc920e6cdd3ede4> al-khwarizmi engineering journal,vol. 13, no. 1, p.p. corrosion behavior of nanocomposite al with mustafa k. ismeal* kharia s. *,**department of mechanical techniques/ institute of technology/ middle technical university *** department of production and metallurgy (received 25 https://doi.org/10.22153/kej.2017.08.00 abstract an effort is made to study the effect of composite nanocoating using aluminum different percentage (0.5,1,2,4)wt.% of carbon nanotubes (cnts) using plasma spraying. the effect of this composite on corrosion behavior for aa6061-t6 by extrapolation tafel test in sea water 3.5wt% nacl was invested. many specimens where prepared from aa6061-t6 by the dimension (15x15x3)mm as this first set up and other steps include coating process, x-ray diffraction and sem examination .th nanocomposite coatings with increasing the weight percentage of cnts within the al layer itself has less corrosion rate if compared with both nanocomposite coating and keywords: aluminum-9%silicon, aa6061 1. introduction the new researches elaborate on aluminium based composite found its exhibit many achievable fascinating material properties such as stiffness, wear resistance, specific strength, damping properties with less coefficient of thermal expansion when its compared with the conventional aluminium alloys [1]. al are used extensively for automobile applications because their high corrosion resistance owing to low density [2]. the addition of carbon nanotubes (cnts) as reinforcement for metal matrix composite will perform a remarkable enhancement in the physical and mechanical properties [3]. researches where used carbon to obtain reinforcement of al-si alloys to achieve combination of high strength and high modulus of elasticity of fiber and high toughness of the matrix [4]. in cnts where the tensile strength of maximum layer ranged from 11 63 gpa and the young's modulus variant from 270950 gpa [5]. the aluminum has tendency to forming oxide khwarizmi engineering journal,vol. 13, no. 1, p.p. 6673 (2017) corrosion behavior of nanocomposite al-9 wt% si alloy reinforced with carbon nanotubes kharia s. hassan** hussian a. hussian*** *,**department of mechanical techniques/ institute of technology/ middle technical university production and metallurgy engineering / university of technology *email: mustafa@mtu-irq.com 25 january 2016; accepted 16 august 2016) 6https://doi.org/10.22153/kej.2017.08.00 an effort is made to study the effect of composite nanocoating using aluminum-9%wt silicon alloys reinforced with different percentage (0.5,1,2,4)wt.% of carbon nanotubes (cnts) using plasma spraying. the effect of this composite t6 by extrapolation tafel test in sea water 3.5wt% nacl was invested. many t6 by the dimension (15x15x3)mm as this first set up and other steps include ray diffraction and sem examination .the results show the cnts increase the corrosion rate of the nanocomposite coatings with increasing the weight percentage of cnts within the al-si matrix. al layer itself has less corrosion rate if compared with both nanocomposite coating and the substrate of aa6061 -t6, nanocomposite, cnts, corrosion, plasma spraying. the new researches elaborate on aluminiumbased composite found its exhibit many achievable fascinating material properties such as stiffness, wear resistance, specific strength, damping properties with less coefficient of red with the conventional aluminium alloys [1]. al–si alloys are used extensively for automobile applications because their high corrosion resistance owing to low density [2]. the addition of carbon nanotubes (cnts) as reinforcement for metal matrix ite will perform a remarkable enhancement in the physical and mechanical properties [3]. researches where used carbon to si alloys to achieve combination of high strength and high modulus of of the matrix [4]. in cnts where the tensile strength of 63 gpa and the 950 gpa [5]. the aluminum has tendency to forming oxide film, thus oxide films protect the aluminum against chloride ion attack [6investigate of aluminum corrosion behavior. a corrosion behavior of pure aluminum and aluminum alloy were investigated with salt media compering with other media by gruba also aluminum silicon alloy (al on pitting corrosion when it's immersed in 0.5m nacl solution with current density (i 0.96 µa/cm 2 [10,11]. aluminum aa6061 alloy has excellent corrosion resistance with medium mechanical strength, it has the highest strength of the 6000 series alloys. alloy aa6061 t6 is known as a structural alloy. however, this alloy has best resistance to corrosion when the amount of silicon does not exceed the amount of high level which combines with the magnesium content to form mgsi [12]. gopi and were measured corrosion rate of aa6082 3.5 %nacl solution media is typically 1.95 mpy and the current density (icorr.) equals 4.27 µa [13]. al-khwarizmi engineering journal 9 wt% si alloy reinforced hussian a. hussian*** *,**department of mechanical techniques/ institute of technology/ middle technical university engineering / university of technology 9%wt silicon alloys reinforced with different percentage (0.5,1,2,4)wt.% of carbon nanotubes (cnts) using plasma spraying. the effect of this composite t6 by extrapolation tafel test in sea water 3.5wt% nacl was invested. many t6 by the dimension (15x15x3)mm as this first set up and other steps include e results show the cnts increase the corrosion rate of the si matrix. al-9wt%si coating the substrate of aa6061-t6. t6, nanocomposite, cnts, corrosion, plasma spraying. film, thus oxide films protect the aluminum -8]. many authors investigate of aluminum corrosion behavior. a corrosion behavior of pure aluminum and aluminum alloy were investigated with salt media compering with other media by grubač at el. [9]. also aluminum silicon alloy (al-9wt%si) effects on pitting corrosion when it's immersed in 0.5m nacl solution with current density (icorr.) equal [10,11]. aluminum aa6061-t6 alloy has excellent corrosion resistance with medium mechanical strength, it has the highest 00 series alloys. alloy aa6061t6 is known as a structural alloy. however, this alloy has best resistance to corrosion when the amount of silicon does not exceed the amount of high level which combines with the magnesium content to form mgsi [12]. gopi and manonmani, were measured corrosion rate of aa6082-t6 in 3.5 %nacl solution media is typically 1.95 mpy ) equals 4.27 µa/cm2 mustafa k. ismeal al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 6673(2017) 67 in this research, was aimed to study corrosion behavior of al-9wt%si/mwnts nanocomposite coating materials in sea water with different portion of mwnts as compared with al-9wt%si alloy its self were investigated. 2. experimental the base alloys aa6061-t6 are used for many applications as the matrix material, aa6061-t6 where purchased of aalco metals limited, uk. the chemical composition analysis is carried out using the arl spectrometer instrument as indicated in the table (1). many corrosion specimens from base material were prepared in the dimensions of (15x15x3)mm according to astm (g71-31) aluminum 9%wt silicon powder of particle size 15-70 µm were purchased from phoenix scientific industry ltd., uk (psi) high purity of a multiwall carbon nanotubes (80 wt%) (20-70)nm diameter (1-3)µm in length were purchased from arry international group limited, germany. xrd and arl analyses for alloy aa6061-t6 had been done after surface preparation the xrd and electrochemical corrosion test had been done at ministry of scientific and technology, iraq. table 1, chemical composition of al alloy aa6061-t6. 3. preparation of composite materials the composite materials were prepared by mixing particles of al-9%si wt%, with carbon nanotubes which added in different percentage (0.5,1,2,4)wt.% using powder metallurgy technique. the produced composite materials were used for coating the base aluminum alloys aa6061-t6 with about 100 µm by using plasma spraying technique with automated robot apparatus. plasma spray technique which is cold coating process used “plasma” as a source of heat the power (composite powder) where pass through the plasma jet in end of the plasma gun nuzzle. the plasma heat up nearly the powder to mushy state then the particles flight by the compose gases (argon, hydrogen and helium) to strike on the flat substrate which is aa6061-t6. however, in order to observe the effect of coating layer on corrosion behavior after completing coating, the composite specimens were categorized and sorted into groups as shown in table (2). table 2, categorization of specimens for composite. 4. x-ray diffraction x-ray diffraction test was investigated on specimens (b, c, d, e, and f) groups of table (2), and phase analysis results for specimens group are shown in figure (1). sem topography and optical microscope (an cross-section) of the coating layer was observed the coating layer in figure (2). the element wt% si max. fe max. cu max. mn max. mg max. cr max. zn max. ti max. al bal. actual aa6061-t6 alloy 1.05 0.25 0.08 0.9 0.8 0.01 0.12 0.09 _ nominal (standard) value of aa6061-t6 0.7-1.3 0.5 0.1 0.4-1 0.6-1.2 0.25 0.2 0.1 _ specimens symbol state of specimens a aa6061-t6 base alloy b as recived al-9wt%si alloy c al-9%si alloy with 0.5wt% cnts nanocompsite d al-9%si alloy with 1wt% cnts nanocompsite e al-9%si alloy with 2wt% cnts nanocompsite f al-9%si alloy with 4wt% cnts nanocompsite mustafa k. ismeal al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 6673(2017) 68 scanning electron microscope (sem) was used for micrographs of composite specimens as shown in figure (3) for (b) specimens. fig. 1. xrd phase analysis for al-si\cnts nanocomposite coating specimens. fig. 2. sem micrograph show the splat of al9wt%si/0.5wt% cnts nanocomposite (a). in the right side (b) show an optical microscope crosssection for previous sample. fig. 3. sem micrograph of specimens (c) shows mwnts are embedded in al-si matrix. fig. 4. sem micrographs of 1b,1c,1d,1e and 1f specimens before corrosion test on the left-side, optical micrographs of 2b,2c,2d,2e and 2f after tafel test on the right-side. por 1d 1e 1 2d 50µm pits pi 2e 50µm 2f 50µm c2 50µm b2 50 1c 1b al-si9%wt. mwnts a splats 1 6 0 µ m b al (111 ) al (200 ) al (220 ) al (222) si (111 ) si (220 ) si (311 ) al (31 1) mustafa k. ismeal al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 6673(2017) 5. electrochemical corrosion test electrochemical corrosion test was implemented by tafel extrapolation method using a wenking mlab multi channels potentiostat and sci-mlab corrosion measuring system from bank electroniks-intelligent control gmbh, germany 2007, this test was carried out at room temperature in ministry of science and technology / department of materials as shown in figure (5). tafel equation is used for electrochemical kinetics related to an electrochemical reaction to the over potential. for a single electrode tafel equation specified as; � � � � ln � �� … (1) where, � is the overpotential � is tafle v plot i is the current density, a/m2 and i0 is the so-called "exchange current density", a/m2. fig. 5. the electrochemical corrosion unit. the polarization apparatus measurements were carried out in a corrosion cell having three electrodes of electrochemical cell. the cell contain platinum foil as auxiliary electrode, reference is a saturated calomel electrode (sce) and working electrode. the aa6016-t6 and aa6016-t6/coated samples was mounted as a working electrode and the exposed area was 10 cm2 for one side. the corrosion solution was amid of 3.5wt% nacl, which done by dissolved 35wt% gm. of nacl in 1000 ml of distilled water. the ph meter of solution where measured was found 6.9. high precision ph meter of ±0.01ph, ±1mv, ±0.4ºc model ph-2602 ph/orp/temp meter was calibrated by using two buffers, ph 7 buffer and ph 4 buffer. the working temperature was maintained at ambient temperature (25°c) monitoring by thermometer, there was no significant change of temperature during the procedure. first when the sample mounted in working electrode (we) the potential difference between working electrode and reference electrode measured the open circuit polarization (ocp) without polarizing the reference electrode. next step applying potential difference to a preset voltage and force a current through the counter electrode towards the working electrode in order to counteract the difference between preset voltage and existing working electrode potential. in order to apply tafel equation the tangent line for cathode and anode curve where automatically occur by program fitting. then the point cross of both two lines express the corrosion current (i corr.). for the cycling the polarized anode curve for period of experiment time will exhibit a loopline due to the breaks down of the protective film. the point of cross loop express as pitting current (i pitt.). cell current readings were taken during slow sweep of the potential. the range was taken from (-100 to + 100) mv relative to (ocp). scan rate defines the speed of the potential sweep was taken 10 mv/sec. in this range, the current density versus voltage curve is almost nearly linear. in this test, aluminum alloy (aa6061-t6) coating by composite material and uncoated specimens were placed on working electrode w.e. calomel saturated electrode was immersed in salt solution bath as reference electrode, all samples immersed in nacl solution of 3.5wt.% which indicate ph was 6.8. this test is used to find out corrosion parameters, like corrosion potential ecorr. and corrosion current icorr. for each specimen, which has amount cnts in the coating layer. the parameters latter will use to calculate corrosion rate by using c.r equation below [14]. �. ������ � 0.13 � �����. � ��.��� … (2) where; c.r(mpy); is milli-inches per year, icorr.; is the corrosion current density (µα/cm2), eq.wt; refers to equivalent weight of the corroding species, ρ ; is the density of the corroding specimens, (g/cm 3 ). the values for the corrosion potentials and corrosion current densities were estimated from the intersection of the anodic and cathode tafel lines. the corresponding corrosion potentials (ecorr), corrosion current density (icorr), anodic listed in table (3) and figure (6). mustafa k. ismeal al table 3, the results of electrochemical corrosion in sea water fig. 6. electrochemical behavior polarization for all specimens. fig. 7. electrochemical cycling for coating layers of al-9wt%si/mwnts nanocomposite. 6. discussion in the figure (1) shows the result of x diffraction (xrd) patterns of all specimens in table (2). according the xrd pattern of 2 verses intensity peaks, aluminum and silicon peaks are shown with aluminum peaks (111),(200),(220),(311),(212) plans and silicon (111) plan with very small peaks detected by the xrd program (220) and (311) plans. the mwnts are not clearly shown in the xrd graphs but its detected by program with slightly small specimens symbol ocp [mv] icorr.[µa/cm sce a -848.7 10.31 b -808.4 1.12 c -678.7 4.65 d -597.6 22.57 e -590.1 29.43 f -528.7 31.5 al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 70 the results of electrochemical corrosion in sea water. fig. 6. electrochemical behavior polarization for all fig. 7. electrochemical cycling for coating layers of in the figure (1) shows the result of x-ray diffraction (xrd) patterns of all specimens in according the xrd pattern of 2θ verses intensity peaks, aluminum and silicon peaks are shown with aluminum peaks (111),(200),(220),(311),(212) plans and silicon (111) plan with very small peaks detected by the xrd program (220) and (311) plans. the are not clearly shown in the xrd graphs but its detected by program with slightly small peaks intensities in case of 2wt% and 4wt% of cnts, this is due to the small amount of cnts which is below the detection limit of the x counter and also the dispersion of cnts in al 9wt%si particles so the majority of mwnts are embedded in the matrix, this confirmed in micrograph shown in figure (3). in figure (2 sem micrograph for the topography of the coating layer for specimen (c), its reveals the splat of the coating formation and built up during aps. an optical microscope examination shown in figure (2-b) for the cross-section of coating layer for aps after etching (hf 0.5 vol. %, distilled water 95 vol. %). the coating thickness was measured is between (100 figure (4) sem topography image and optical microscope for (b, c, d, e and f) specimens for al-9wt%si plasma spraying coating surface. the coating surface the surface tend to be rough with having pores. each splats were composed of al 9wt%si and mwnts. the fully melted liquid particles (al-si) during flight will form lamella when impacted on the substrate. thus, a rapid solidification of the splats occurred upon impact due to high cooling rates of the splat. the cooling rate of the splats was reported in the literature as 106 and 107 k.s−1. the pores are formed between lamellar structures due shrinkage of lamellar cause by rapid solidification of al or lamellae formation of al 9wt%si/1wt%mwnts composite formed during plasma spraying are rough but the splash fingers are connected. the coating surface has some pores due to shrinkage of splat of aluminum matrix nanocomposite with mwnts embedded in al-si matrix. some mwnts have settled on the top surface that could clearly show in figu figure (6) shows the polarization curves of all specimens which categorized in table (2). these figures sign that the cathodic and anodic polarization curves are similar in the corrosion behavior for the base (aa6061 composites (al-9wt%si/mwnts) in 3.5%nacl solution but they are different in the corrosion [µa/cm 2 ] sce ecorr.[mv] corrosion rate [ mm.year-1] (m.p.y) 10.31 -858.3 4.433 -803.3 0.481 -530.7 1.999 22.57 -598.4 9.705 29.43 -603.1 12.654 -768.2 13.545 khwarizmi engineering journal, vol. 13, no. 1, p.p. 6673(2017) peaks intensities in case of 2wt% and 4wt% of cnts, this is due to the small amount of cnts which is below the detection limit of the x-ray ion of cnts in al9wt%si particles so the majority of mwnts are embedded in the matrix, this confirmed in micrograph shown in figure (3). in figure (2-a) sem micrograph for the topography of the coating layer for specimen (c), its reveals the coating formation and built up during aps. an optical microscope examination shown section of coating layer for aps after etching (hf 0.5 vol. %, distilled water 95 vol. %). the coating thickness was measured is between (100160) µm. in figure (4) sem topography image and optical microscope for (b, c, d, e and f) specimens for 9wt%si plasma spraying coating surface. the coating surface the surface tend to be rough with having pores. each splats were composed of ald mwnts. the fully melted liquid si) during flight will form lamella when impacted on the substrate. thus, a rapid solidification of the splats occurred upon impact due to high cooling rates of the splat. the cooling eported in the literature as . the pores are formed between lamellar structures due shrinkage of lamellar cause by rapid solidification of al-si. the splats or lamellae formation of al9wt%si/1wt%mwnts composite formed during ng are rough but the splash fingers are connected. the coating surface has some pores due to shrinkage of splat of aluminum matrix nanocomposite with mwnts embedded in si matrix. some mwnts have settled on the top surface that could clearly show in figure (3). figure (6) shows the polarization curves of all specimens which categorized in table (2). these figures sign that the cathodic and anodic polarization curves are similar in the corrosion behavior for the base (aa6061-t6) and wnts) in 3.5%nacl solution but they are different in the corrosion corrosion rate ipitt.[ma/cm 2 ] 1.7 0.6642 0.6728 0.6819 0.7052 0.9955 mustafa k. ismeal al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 6673(2017) 71 current density and corrosion potential. the potential of corrosion depends on the electrochemical behavior and the quantity of alloying elements such as silicon and magnesium in table (3) specimen (a) has a corrosion potential of -858.3mv and a corrosion current of 10.31µa/cm2 and the corrosion rate is 4.433 m.p.y. the corrosion is taken place due to the presence of chloride ions which released and combine with hydrogen to formed hydraulic acid. the hydrochloric acid increase corrosion rate accelerated by elements are presence in the microstructure. the corrosion behavior in specimens (b) gives low corrosion rate comparing with specimens (a), this is due to combine and encourage of boundaries between the of al-rich (α) phase and silicon particles in refined microstructures, since such boundaries are more sensitive to the corrosion action . from table (3), it was seen that a nanocomposite with in specimens (d, e and f) has high corrosion current density (high corrosion rate) than that nanocomposite with (b and c) this would refer the mwnts has play role of increasing corrosion rate by localized pitting corrosions because the cnts behave as negative (more noble) than the alloy content. this explained by aung et al. [15] where microgalvanic action between the cathodic cnts and the anodic of elements less corrosion resistance in the matrix in 3.5wt% nacl. more than 2wt of mwnts in the al-9wt%si will tend to be agglomerated, therefore the ion exchanged will reduced, as well as high porosity which a accompanied of high mwnts contents will make the corrosion more faster. matrix which reduces the cathodic areas to localized regions such as impurities, porosities and reinforcements in the alloy matrix. the specimen (c) gives lower corrosion rate due to less amount reinforcement (mwnts), but the still al-si protective coating layer (specimen b) without adding reinforcement has less corrosion rate. figure (7) shows the electrochemical cycling corrosion, in this figure revels the pitting where start for coated samples almost closes each other but in table (3) the ipitt. are increases with respect of amount mwnts that’s confirmed the mwnts breaking down the coating layer by accelerating the pitting corrosion. 7. conclusion 1. corrosion tests results have shown that al alloy 9% silicon samples tend to yield lower corrosion rate than aa6061t-6 alloy in 3.5 wt% nacl solution. 2. the external appearance s of the cathodic and anodic members of the deposit al-9wt% si alloy sample depict representative pitting reactions, differently to that exhibited for composite specimens . 3. nanocomposite with 0.5wt% mwnts shows lower corrosion rate if compared with other constitute nanocomposite, this refers to the cnts would enhanced pitting corrosion rate. 8. references [1] jailani, h. siddhi, a. rajadurai, b. mohan, a. senthil kumar, and t. sornakumar. 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[10] eid, salah, m. abdallah, e. m. kamar, and a. y. el-etre. "corrosion inhibition of aluminum and aluminum silicon alloys in sodium hydroxide solutions by methyl cellulose.", j. mater. environ. sci. vol. 6, no. 3, 2015, pp. 892-901. [11] wislei r. osório, noé cheung, leandro c. peixoto and amauri garcia, “corrosion resistance and mechanical properties of an al 9wt%si alloy treated by laser surface remelting”, int. j. electrochem. sci., vol. 4, 2009, pp. 820 – 831. [12] afsa, pocket guide 3, “corrosion resistance of aluminium and protective measures where appropriate”, 1st edit., afsa compiled and publisher, south africa, 2011. h. s. patil1, s. n. soman, “corrosion behaviour of friction stir welded aluminium alloys aa6082-t6”, amr. j. of mat. eng. and tech., vol. 2, no. 3, 2014, pp. 29-33. [13] s. gopi and k. manonmani, “microstructure and mechanical properties of friction stir welded 6082-t6 aluminium alloy”, aus. j. of mech. eng., vol. 11, 2013, pp. 131-137. [14] annual book of astmstandards, standard practice for calculation of corrosion rates and related information, g102-89,vol. 03.02, 2004. [15] naing naing aung, wei zhou, chwee sim goh, sharon mui ling nai and jun wei, “effect of carbon nanotubes on corrosion of mg–cnt composites”, corrosion science 52 (2010) 1551–1553. �� ا������ �� �� 1، ا���د��13 � ا���ارز�� ا������� ا��� � ���� ،2017( 73-66( 73 ا���0اة �. ا!+�-�, ا���+�*� al-9wt% si) (�� �"�ن –� �ك ا�'&%� �$#�"� ا!�����م cnts �� ا������ �� �3*� � ��ن 1$2* �� **1�$2 � 1�$2 �*** *،** �� � ���/ ���اد -���� ا���� � ا����� ا���� ا�� � ا%$� ج وا�!� دن***��/ ()' ھ���� � � ا������ ا�� irq.com-mustafa@mtu: ا�-+,� ا%���+و$** ا��4�� � .* ا�! اد , $ ن 4 3�+ ا���2ام ا$ ��0 ا�� ر� ن ا���� '4 ���.* ھ6ه ا��را, $ � ا:�al-9wt%si 9 �8 ا�!�+ا7-� ا��, $ ; ا$ ��0 ا�� ر� ن ا�� (cnts) �� ا%�!�� م ��wt% (0.5,1,2,4))0 وز$���-� دة �+7-� وا���2ا�� طaءً -%9wtا�� �)< ق �8 � �de ل g>d� ن ��d�� وا(� ���-(� ن ا%�!�� م��d�� م -�(����)aa6061-t6( � � ا�+ش � �-aز�� اة ��+,� ت �8 ا�)-��� ا�!��e j��g4 '4 ��)0 و���ھ �. اة ��+ض و7�l�+ ا�! د �� ر ا�� m7 و�-�n15)اx15x3( 'd� . � o>9ار وا� � ا�)���� ���d+ف �de ا%ط�q% � o>9ا� رات �eة ���-�nا m7 ر ا��-�nا ��d!e ;�-� � �ط ر ا�� m7 ا�6ي ا�+ي -�nوا s� ل ��<�* 4 .mا�!��+ ا%���+و$* ا�!!���� ا� ر ا�� m7 وا��* mt!4 ا��� ر وا���� ��+,-�nا uv ء ا�-<+ و�8 $�� w� .* و xy د�� .+اداي ��� z�-��� m7 � وا,� د ���ل ا��, $ � ا��aء ا�! دة ا�!�+ا7-� و,]داد ���ل (cnts)ان ا$ ��0 ا�� ر� ن ا���-�� m��\4],� �8 ���ل ا�� � دة ا��)-,[� m7 ا���� �� ا��aء . ا� ز$��� �al-9wt%si �4ط-, $ و��8 ���%ت m7 m7\4 �8 ا�! دة ا�!�+ا7-� ا������ � ر$�ا(m ���ل m7\4 اذا � 4!; ا�! ً ن -�)-��� ا%�!�� م�a�dء وا,^��d�� م -�(����aa6061-t6 . حسين وسعاد وعبد الجبار al-khwarizmi engineering journal, vol. 10, no. 2, p.p. a new cumulative damage model shot peening treatment hussain j. m.alalkawi abdul *department of electromechanical *** department of biomedical engineering *e-mial: **e***e-mial: (received 16 abstract in this paper, fatigue damage accumulation were studied using many marsh(cdm), new non-linear model and experimental classical methods, corton-dalon (cd)andcorton respectively. however satisfactory predictions were obtain model) for medium carbon steel compared with experimental work are related to their inability to take into accou model shows that a much better and conservative prediction of fatigue life in comp the prediction of the present model gave slightly below the experimental data while the cdm gave overestimate prediction and cd showed strongly underestimates the life of specimens. keywords: cumulative fatigue damage, shot peening, non 1. introduction only a few machine parts are subjected to static loading but many of machine parts are subjected to variable loads. the variable loads have been found by experiment that when a material is subjected to dynamic loads. it fails at a stress below the yield point; such type of failure is known as fatigue. fatigue may be constant or variable. constant fatigue loading is defined as fatigue under cyclic loading with constant amplitude and a constant mean stress or load in service the structures or components are subjected to variable amplitude loading, which can be a rather complex load time history [1]. variable loading or cumulative damage is usually investigated by testing specimens with a definite number of cycles at one stress level, and khwarizmi engineering journal, vol. 10, no. 2, p.p. 5764 (2014) damage model for fatigue life prediction under shot peening treatment hussain j. m.alalkawi* saad a. khuder al saraf** abdul-jabar h. ali*** electromechanical engineering/ university of technology **ministry of education engineering /al-khawarizmi college of engineering/ university of baghdad mial: alalkawi2012@yahoo.com -mial: alsaraf_saad @yahoo.com mial: dr.abduljabarha @yahoo.com 16 december 2013; accepted 15 april 2014) mulation were studied using many methods i.e.corton-dalon (cd linear model and experimental method. the prediction of fatigue lifetimes based on the two corton-dalon-marsh (cdm), are uneconomic and non respectively. however satisfactory predictions were obtained by applying the proposed non-linear model (present compared with experimental work. many shortcomings of the two classical related to their inability to take into account the surface treatment effect as shot peening. it is c model shows that a much better and conservative prediction of fatigue life in comparison with cd and cdm methods. prediction of the present model gave slightly below the experimental data while the cdm gave overestimate cd showed strongly underestimates the life of specimens. damage, shot peening, non-linear model. only a few machine parts are subjected to static loading but many of machine parts are variable loads have been found by experiment that when a . it fails at a uch type of failure is known as fatigue. fatigue may be constant or variable. constant fatigue loading is defined as fatigue under cyclic loading with constant amplitude and a constant mean stress or load. but in service the structures or components are subjected to variable amplitude loading, which can be a rather complex load time history [1]. variable loading or cumulative damage is usually investigated by testing specimens with a cles at one stress level, and then to continue the test at other stress level until failure. in these various stress level tests, the stresses may be either in an increasing decreasing order or mixed together [ study a new cumulative fatigue damage model for life prediction will presented involving the effects of loading sequences and the surface treatment. 2. fatigue damage accumulation for long time, researchers have tri the best theory to explain the fatigue damage accumulation behavior. a comprehensive review can be found in [3]. only a few damage accumulation theories are briefly described below. al-khwarizmi engineering journal prediction under ** khawarizmi college of engineering/ university of baghdad cd),corton-dalone lifetimes based on the two , are uneconomic and non-conservative linear model (present . many shortcomings of the two classical methods it is clear that the new arison with cd and cdm methods. prediction of the present model gave slightly below the experimental data while the cdm gave overestimate then to continue the test at other stress level until failure. in these various stress level tests, the stresses may be either in an increasing or decreasing order or mixed together [2].in this amage model for life prediction will presented involving the effects and the surface shot peening ccumulation , researchers have tried to find the best theory to explain the fatigue damage accumulation behavior. a comprehensive review can be found in [3]. only a few damage accumulation theories are briefly described below. mailto:@yahoo.com mailto:@yahoo.com mailto:@yahoo.com hussain j. m.alalkawi al-khwarizmi engineering journal, vol. 10, no. 2, p.p. 5764 (2014) 58 miner [4] first expressed the concept of cumulative fatigue damage in a mathematical formula as, = = 1 … (1) where, is the cumulative fatigue damage and , are the applied cycles and the number of cycles to failure under i-th constant s-n curve stress level respectively. corton-dolan theory [5] was based on the modification the s-n diagram. they suggested obtaining the slope of the modified s-n line from the average results of the few repeated two-step block tests expressed as: = + (1 − ) … (2) where is the number of cycles to failure, is the number of cycles to failure at high stress in a constant amplitude test, is the fraction of cycles at , is the ratio of rate of damage, and is an exponent. corton-dolan found that was related to the stress amplitude by the empirical equation: =[ ] … (3) where, is the lower stress, and is the inverse slope of s-n curve on a log-log plot. marsh [6] modified the corton-dolan method to include the stress amplitude below the fatigue limit into account. miller et al [7] showed that damage can be initiated by cycling at stresses below the fatigue limit and so the 0.8 of the fatigue limit stress level was used in conjunction with the corton-dolan s-n curve rule. the new method is presented here was named as cortondolan-marsh theory (cdm). more details about cdm theory can be seen in [7]. yougming and sankaran [8] proposed a general methodology for stochastic fatigue damage modeling under variable amplitude loading. this model describes the cumulative fatigue damage in a nonlinear formula which predicts the fatigue life and improves the accuracy of the miner rule. two levels fatigue damage model was proposed by z. yang et al [9] for low cycle fatigue (lcf) and high cycle fatigue cumulative fatigue damage. the results showed that the predictions of the lives are in good agreement with the experimental results. 3. the proposed non-linear model following the work of perreira et al [10], they suggested the damage due to fatigue under variable amplitude stress such as for low-high and high-low stress level as: = [ ] … (4) where, (α) is a function of the applied load. in the present work, (α) defined as the effect of loading sequences and surface treatment, here the surface treatment is shot peening technique. equation (4) can be modified to take the form: = [∑ ] … (5) where, ( ) represents the effect of loading sequences and shot peening treatment, ( ) here ( ) defined as: = … (6) where, is the inverse slope of the s-n curve. equation (6) can be applied from low to high stress level. but when the test program is from high to low stress, equation (6) is changed as following: = … (7) in order to make the prediction safe equation (5) can be divided by the value ( )to become: = [∑ ] … (8) 4. experimental work the current work is based on an experimental program which included 72 fatigue specimens, 48 specimens were tested to establish the s-n curves for both dry (without shot peening) and shot peening treatment. the shot peening was done at 10, 20 and 30 minute, 24 specimens were tested under low-high and high-low stress. all specimens were extracted from a medium carbon steel rod with1m long and 10mm in diameter. the chemical composition of the material used is presented in table (1) while the experimental mechanical properties with the standard values are listed in table (2). hussain j. m.alalkawi al-khwarizmi engineering journal, vol. 10, no. 2, p.p. 5764 (2014) 59 table 1, chemical composition of medium carbon steel in wt. %. element c si mn s fe experimental 0.4 0.13 1.04 0.002 blance table 2, mechanical properties of medium carbon steel. mechanical properties yield strength (mpa) ultimate strength (mpa) elastic modules (gpa) hv experimental 295 585 207 184 5. fatigue test procedure the specimens were prepared according to din 50113.the specimens are manufactured using programmable cnc lathing machine. figure (1) shows the fatigue test specimens and its configuration. all fatigue tests were carried out in the laboratories of electromechanical engineering department, university of technology using fatigue testing machine type punn rotating bending figure (2). the experiments were conducted at room temperature and at stress ratio r=-1(minimum stress to maximum stress in periodic cycle), while the shot peening device with its properties can be seen in ref. [12]. fig. 1. specimen geometry and dimensions for fatigue test (all dimensions in mm). 0.5×45° 30 30 80 ø 10 ǿ 6. 74 r=30 20 hussain j. m.alalkawi al-khwarizmi engineering journal, vol. 10, no. 2, p.p. fig. 2. punn rotary fatigue bending machine 6. results and discussion constant stress amplitude with stress ratio (r=-1) at room temperature tests were conducted in order to use the parameter ( , inverse slope of s-n curve) for driving the present model. the final results can be summarized in table ( table 3, basic s-n fatigue results at room temperature (rt) description dry (without shot peening) with shot peening (spt) 10 min. with shot peening (spt) 20 min. with shot peening (spt) 30 min. 6.1. variable amplitude results (cumulative fatigue damage) the cumulative fatigue damage tests have been conducted for two-steps program low khwarizmi engineering journal, vol. 10, no. 2, p.p. 60 punn rotary fatigue bending machine. stress ratio were conducted , inverse slope of n curve) for driving the present model. the final results can be summarized in table (3) equation of power law regression is given (fatigue life formula). = where, ( ) is the applied stress, and ( fitting parameters. the regression represent of the fatigue trends. room temperature (rt). b a -0.235 5623 -0.296 7650 -0.252 9120 -0.272 10690 variable amplitude results the cumulative fatigue damage tests have steps program low-high and high-low stress for the conditions mentioned in table (4). the experimental cumulative fatigue damage results are listed in table (4 khwarizmi engineering journal, vol. 10, no. 2, p.p. 5764 (2014) equation of power law regression is given by … (9) ) is the applied stress, and (a),(b) are the regression constants nditions mentioned cumulative fatigue results are listed in table (4). hussain j. m.alalkawi al-khwarizmi engineering journal, vol. 10, no. 2, p.p. 5764 (2014) 61 table 4, experimental cumulative fatigue damage results. 6.2. comparison between fatigue life prediction methods comparisons between the four methods of fatigue life prediction can now be done. the predictions of fatigue lifetime using corton-dolan (cd) and corton-dolan-marsh (cdm) methods with the experimental and the new model results are illustrate in table (5). table 5, comparison between fatigue lives prediction between four methods. the cd and cdm have been shown not to be satisfactory for predicting life in a two-step loading due to their inability to take into account the effect of shot peening which decelerate the short cracks. figures (3 and 4) show the four methods in comparison for predicting the fatigue life with the experimental results. nf(cycles) average amplitude stress (mpa) loading program description 487000 130467 275-450 450-270 low-high high-low dry (without shot peening) 954000 195000 275-450 450-270 low-high high-low with shot peening (spt) 10 min. 1623330 353210 275-450 450-270 low-high high-low with shot peening (spt) 20 min. 1077261 188200 275-450 450-270 low-high high-low with shot peening (spt) 30 min. nf cycles model nf cycles experimental nf cycles cdm nf cycles cd loading program spt min. 469913 124605 487000 130467 1388436 494209 32103 85837 low-high high-low dry 849175 183003 954000 195000 2312581 670972 45299 68259 low-high high-low spt10 1288140 238894 1623330 353210 3538197 1402019 50813 70423 low-high high-low spt20 805395 159619 1077261 188200 2635364 460404 42319 57176 low-high high-low spt30 hussain j. m.alalkawi al-khwarizmi engineering journal, vol. 10, no. 2, p.p. 5764 (2014) 62 fig. 3. shows the low-high cumulative fatigue life prediction for four methods. fig. 4. shows the high-low cumulative fatigue life prediction for four methods. it is clear that the new model shows that a much better and conservative prediction of fatigue life in comparison with cd and cdm methods. the prediction of the present model gave slightly below the experimental data while the cdm gave overestimate prediction and cd showed strongly underestimates the life of specimens. 7. conclusions 1. for this particular loading and metal used, the proposed non-linear model (present model) seems to be a proper choice for cumulative fatigue damage life prediction. 2. the cdm predictions showed that nonconservative prediction (overestimate the life) based on the experimental results. 0 500000 1000000 1500000 2000000 2500000 3000000 3500000 4000000 dry spt10 spt20 spt30 cdm cd experimantal model 0 200000 400000 600000 800000 1000000 1200000 1400000 1600000 dry spt10 spt20 spt30 cdm cd experimantal model hussain j. m.alalkawi al-khwarizmi engineering journal, vol. 10, no. 2, p.p. 5764 (2014) 63 3. the cd method gave uneconomic predictions(strongly underestimates the life) compared to the experimental results. 8. references [1] n. e. frost, k. j. marsh and l. p. pook “metal fatigue” clarendon press, oxford (1974). [2] alakawi h. j. m. “cumulative fatigue damage under varying stress range conditions” phd. thesis, university of sheffield uk (1986). [3] fatemi, a. yang l. “cumulative fatigue damage and life prediction theories: a survey of the state of the art for homogenous materials” int. j. fatigue, 20-9-34 (1998). [4] miner m. a. “cumulative fatigue damage” j. of applied mechanics, 67, a159-a164 (1945). [5] corten h. t. and dolon t. j. “cumulative fatigue damage”proc. int. conf. fatigue of metals, london, instn. mech. eng., pp234246 (1956). [6] marsh k. j. “cumulative fatigue damage under symmetrical saw tooth-loading program” mech. eng. science, 7, pp. 138151(1965). [7] miller k. j., mohamed h. j. and de los rios. “fatigue damage accumulation above and below the fatigue limit” european group on fracture publication no. 1, egfi, instn.mech. eng. london (1986). [8] yongming liu, sankaranmahadevan “stochstic fatigue damage modeling under variable amplitude loading” international journal of fatigue 39, 1144-1169 (2007). [9] zhi yong huang, daniele wagner, claude bathias, jean louis chaboche “cumulative fatigue damage in low cycle fatigue and high cycle fatigue for low carbon-manganese steel” international journal of fatigue 33, 115-121 (2011). [10] h. f. s. g. perreira, a. m. p. jesus, a. s. ribeiro, a. a. fetenades “fatigue damage behavior of structural components under variable amplitude loading” mechanica experimental, vol. 17, 75-85 (2009). [11] h. j. alalkawi, kiffaya a. al saffar, mohammed j. k. “fatigue-creep interaction of copper alloy c35600 under variable temperature” implementation of postgraduates researchers to serve the society 7-8may (2012) al mustansiriya university. [12] h. j. alalkawi, r. a. mairb, n. a. fatin “shot peening treatment as a barrier to fatigue crack propagation in pure shear for medium carbon steel” journal of al-taqani (2010). )2014( 5764، صفحة 2، العدد10دجلة الخوارزمي الھندسیة المجلم حسین جاسم 64 للتنبؤ بعمر الكالل تحت تأثیر معالجة السطوح بالنقر المستمر أتموذج الضرر التراكمي الجدید ***عبد الجبار حسین علي** سعد عباس خضر* حسین جاسم العلكاوي الجامعة التكنولوجیة/ قسم ھندسة الكھرومیكانیك * وزارة التربیة/ مدیریة التعلیم المھني ** يوارزمكلیة الھندسة الخ/ الحیاتي قسم ھندسة الطب *** alalkawi2012@yahoo.com : البرید االلكتروني* yahoo.com alsaraf_saad@ :البرید االلكتروني** yahoo.com dr.abduljabarha@ :البرید االلكتروني*** الخالصة دایلن طرق ؛ كورتن عدةبأستخدام )medium carbon steel ( ل لسبیكة الصلب المتوسط الكاربوفي ھذا البحث تم دراسة حساب تراكم ضرر الكال )cd ( ، مارش –دایلن –كورتن (cdm) دایلن یستند تنبأ عمر الكالل على اسلوبین تقلدیین ھما كورتن. بضمنھا االنموذج المقترح مقارنة بالنتائج العملیة (corton-dalon) مارش دایلن و كورتن (corton-dalon-marsh)في حین . وھي غیر أقتصادیة وغیر دقیقة مقارنة مع النتائج العملیة على التوالي یرتبط العدید من أوجة القصور . الكالل للسبیكة التي استخدمت في البحث بأستخدام االنموذج الالخطي المقترح مناسبا مقارنة بالنتائج العملیةكان التنبأ بعمر االنموذج ).shot peening( نقر المستمرفي االسالیب الكالسیكیة التقلیدیة المشار الیھا بعدم قدرتھا على أن تأخذ في االعتبار تأثیر المعالجة السطحیة مثل ال اعطى نتائج اعلى بكثیر من النتائج العملیة وان اسلوب cdmمن النتائج العملیة في حین ان اسلوب بقلیل المقترح لتنبأ بعمر الكالل اعطى نتائج تقریبا اقل cd اعطى نتائج اقل بكثیر من النتائج العملیة. mailto:@yahoo.com mailto:@yahoo.com mailto:@yahoo.com 121128 al-khwarizmi engineering journal al-khwarizmi engineering journal,vol. 12, no. 3, p.p. 121128 (2016) mechanical properties of mig joints for dissimilar aluminum alloys (2024-t351 and 6061-t651) nawres jabar nasser institute of technologybaghdad email: nawresjabaar@yahoo.com (received 14 september 2014; accepted 12 may 2016) abstract the research aims to investigate the effects of gmaw or mig welding process on the mechanical properties of dissimilar aluminum alloys 2024-t351 and aa 6061t651. a series of experimental techniques have been conducted to evaluate mechanical properties of the alloys, by carrying out hardness, tensile and bending tests for welded and unwelded specimens. metal inert gas (mig) has been carried out on sheet metal using er4043(alsi5) as a filler metal and argon as shielded gas. the welded joints were tested by x-ray radiography and faulty pieces were excluded. welding joints without defects are subjected to heat treatment including heating the joints in furnace to 170 °c for half an hour then air cooling to relief welding stress. tensile test was implemented for all specimens which prepared in the dimensions according to astm 17500 by using testing machine smart series with preload value 100 kn. vickers hardness test and microstructure examination were made, the last test was bending test which implemented on the welded and un welded specimens which machined into standard test specimen dimensions. results of mechanical properties using mig welding process appear a general decay compared with un welded and in the dissimilar joint comparing with parent metal that is due to the microstructure change during the welding process. the location of the failure for welded specimens after all mechanical test was found predominantly along the heat affected zone ( haz ).but unwedded specimens were failed near the center line of the specimen. keywords: aluminum alloys, welding joining, dissimilar materials welding technologies, mechanical properties. 1. introduction a wide range of applications for aluminum and its alloys are used successfully in industry, from packaging to aerospace. because it have a good mechanical properties and low densities, [1, 2] .heat treatable aluminum alloys (as such 2024 and 6061) are specially produced for critical applications with advanced mechanical properties of high strength and ductility. the term of gas metal arc welding means a process that melts and joins metals by heating them with an arc arise of the base metal and continuously fed filler wire electrode. during this processes inert gases are used to isolate the weld region from environment effects such as argon and helium which are most widely used in arc welding process for aluminum alloys [3]. designers and technologists confront many difficulties when dealing with the welding of aluminum and its alloys. mainly related to the presence of a tenacious oxide layer, high thermal conductivity, high coefficient of thermal expansion, solidification shrinkage and, above all, high solubility of hydrogen, and other gases, in molten state [4].these difficulties are also arise when welding a heat-treatable alloys, since heat, provided by welding process, after welding there is a decay in mechanical properties, due to phase transformations and softening induced in alloy. for that aluminum alloys are generally classified as low weld ability because of the poor solidification microstructure and porosity in the fusion zone. nawres jabar nasser al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 121128 (2016) 122 also, the loss of mechanical properties as compared to the base material is very significant. these factors make the joining of these alloys by conventional welding processes unattractive, there for there must be fetching for other welding processes [5]. therefore in important applications of aerospace and similar, those special heat treatable alloys are not suitable for conventional welding processes but its need to be friction stir welded [4][6]. the aa6061-t6 alloys can be welded with er4043 (al-si5) or er5356 (al-mg5) filler alloys dependent on weld performance requirements. the properties of aluminum alloy affect on welding process, such as high thermal conductivity, high chemical reactivity with oxygen, and high hydrogen solubility at high temperature. the main consideration is to adequately dilute the mg2si percentage in the base material with sufficient filler alloy to reduce weld metal crack sensitivity. more attention must be taken when welding the 6061-t6 base alloy with the 5356 filler alloys to ensure sufficient additions of filler alloy to prevent the al – mg from crack the sensitivity chemistry range [7]. in addition to the base material used in this study is 2024-t3 aluminum alloy. it is found that copper (cu) gives substantial increases in strength, allows precipitation hardening, reduces corrosion resistance, ductility and weld ability. also in this series of aluminum alloys it is difficult to weld by liquid state join because many of these series are thermal cracking sensitive [8]. the present work investigated the mechanical behavior of welded joints of al2024 and al6061, as well as dissimilar joints between al 2024t351 and al6061t651, using er4043 filler wire and the -gmaw process. 2. experimental procedure 2.1. used alloys plates of 200 mm long, 100 mm wide and 10 mm thick of 2024-t351 and 6061-t651 aluminum alloys which its chemical composition analysis by using arl spectrometer is given in table (1,2) and its stander mechanical properties are shown in table (3) ,were joined together using gmaw process. er4043 was used as a filler metal rod, its chemical composition is shown in table (4).the welded butt joints in dimension of (200*100*8) mm are produced with the preparation angle in shape v of 70⁰ and square angle as shown in fig.(1). these sheets were cleaned before the welding process with a scraper and acetone then they were butt welded (two pass for each side) by a mig350 type semiautomatic welding machine with parameters shown in table (5). s vi inputheat 60 ××= ... (1) [9] where: i= welding current (ampere) v= welding voltage (volt) s= welding speed (m/min) heat input= joule table 1, chemical composition of the used metal aa( 6061 t651) [10]. elements w% measured value standard value si 0.6 0.4-0.8 fe 0.4 max 0.7 cu 0.3 0.15-0.4 mn 0.12 max 0.15 mg 1.0 0.8-1.2 cr 0.2 0.04-0.35 zn 0.18 max 0.25 al rem. rem. table 2, chemical composition of the used metal aa (2024t351)[10]. elements w% measured value standard value [9] al % 92.6 rem ti% 0 0-0.15 cr% 0.05 0-0.1 zn% 0.1 0-0.25 si% 0.4 0-0.5 fe% 0.3 0-0.5 mn% 0.6 0.3-0.9 mg% cu% 1.5 4.4 1.2-1.8 3.8-4.9 table 3, standard mechanical properties of 2024t351 and 6061t651 [6]. mate rial yield strength mpa. ultimate tensile strength ( uts) mps. percentage of elongation % 2024t3 380 464 16 6061t6 295 342 10 nawres jabar nasser al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 121128 (2016) 123 table 4, chemical composition of the filler metal (filer wire er 4043) al si5 [11]. elements wt% actual value nominal value si 5.0 4.5-6 fe 0.4 <0.6 cu 0.1 <0.3 mn 0.08 < 0.15 mg 0.06 < 0.2 cr 0.25 zn 0.15 < 0.1 sn 0.15 al 93.44 rem. table (5) welding parameters of mig welding symbol current (amp.) voltage (v.) travel speed (mm/s) flow rate l/min no. of passes heat input (joule) wire diameter (mm) c 140 22 220 10 2 456120 1.2 d 150 22 110 10 2 977400 1.2 e 160 24 220 10 3 568669 1.2 f 120 24 120 10 3 130320 1.2 fig .1. the welded joints dimension in (mm). 2.2. categorization of welded joint after completing preparation of the specimen, they were categorized to groups as shown in table (6). table (6) categorizing of specimens. 2.3 microstructure test the changes of micro structural from weld zone to the unaffected base material were tested using optical microscope. specimens were prepared in many steps for microstructure test including wet grinding operation using emery paper of different grits (120,320,500, 800 and 1000). polishing process was done by using diamond paste of size (0.3µm) with special polishing cloth. they ere cleaned with alcohol and water and then dried with hot air dryer. etching for the structure by use keller’s reagent consisting of 95 ml distill water, 2.5 ml hno3, 1.5 ml hcl and 1 ml hf then washed after that with me-600 computerized optical microscope provided with a nikon camera, the examined result was shown in fig.(2). symbol condition a aa 6061-t651 as received b aa 2024-t351 as received c butt single v aa 6061-t651 at 70° d butt single v aa 2024-t351 at 70 e butt single v dissimilar aa 6061t651,2024-t351 at 70° f butt single dissimilar aa 6061t651,2024-t351 square butt joint (angle 90°) nawres jabar nasser al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 121128 (2016) 124 specimen (a) specimen (b) specimen (c) specimen (d) specimen (e) specimen (f) fig . 2. the microstructure of (a,b as received and c,d,e,f in weld zone) (40x). 2.4. mechanical tests before implementing the mechanical tests, weld joints were characterized by the visual inspection and x-ray radiography. the radiographic unit was operated for 1 min at 150 kv, 2 ma for the inspection. the joints without defects were used to prepare many specimens for mechanical test. 2.5. tensile test the dimensions of the tensile specimens were prepared according to astm (17500) as shown in fig. (3) multiples of specimens are cut from welded and un welded plates with the condition that loading axis of the tensile test specimens is transverse (perpendicular) to the welding direction of the plates. tensile properties were estimated at room temperature using the computerized tinus olsen universal tensile testing machine. all tensile tests were carried out at a constant crosshead speed of 10 mm/min and the average of three specimens was taken to evaluate the tensile behavior of each welded joint. fig. (4) shows the test specimens after fracture while the test results are shown in table (7) and the relationship between stress and strain are shown in fig. (5) for all specimens. fig. 3. dimensions of tensile test specimen in mm. fig. 4. tensile test fracture specimens. 50 µm 50 µm 50 µm 50 µm 50 µm 50 µm mg2si alcu mg2si nawres jabar nasser al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 121128 (2016) 125 table 7, mechanical tests result. sample σu mpa yield stress σy mpa fb kn elongation % hardness hv(kg\ ) a 270 230 13.42 12 125 b 323 295 11.25 10 130 c 159 123 2.48 9 82 d 165 150 2.18 8 87 e 200 183 2.81 8 84 f 170 152 1.19 10 86 fig. 5. relationship between stress and strain for all specimens. 2.6. bending test the dimensions of bending test specimen were prepared according to the astm (e 190-192) for the welded joint as shown in fig. (6). fig. 6. bending test specimen dimensions in mm. face bending tests were carried out at room temperature using three point's method fig. (7). a cylinder-shaped line load is applied against the weld line, also the center line, of the specimen. as the specimen is supported on the sides by a steel fixture, it begins to yield because of bending. this test was conducted out on a 100-kn universal testing machine at a speed of 3.5 mm/min. the maximum load registered by the machine during bending was used to indicate the strength of the weld joint. fig .7. bending setup (push travel technique). fig. 8. photos of bending test specimens after fracture 2.7. micro hardness test micro hardness test of the welded joints was accomplished using the vickers hardness tester. according to the astm, vickers hardness measurements were taken 2 mm below the top surface of the specimen perpendicular to the welding direction across the weld zone, heat affected zone (haz) and the base materials using nawres jabar nasser al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 121128 (2016) 126 a diamond pyramid indenter with a load of 30 kg and loading within 15 sec. tests, results for all specimens are shown in fig. (9). fig. .9. micro hardness result for all specimens. 3. discussion in this work chemical composition and mechanical properties have been conducted for the material used to check the composition, mechanical properties of the al-alloy type and compare it with the standard, as shown in table (1, 2, 3). the microstructure of base metal aluminum alloy 6061-t651 was shown in fig. (2) specimen (a) observed coarse and elongated grains with uniformly distributed very fine precipitates. the presence of alloying elements such as silicon and magnesium contribute to the higher strength of the base metal. these two elements combined together and subjected to precipitation reaction and form a strengthening precipitate of mg2si. resulting the fine and uniform distribution of these precipitates throughout the aluminum matrix which give higher strength to these alloys [12] and microstructure of base metal aluminum alloy 2024-t351 in fig. (2) specimen (b) reveal coarse dendritic structure and elongated grains with uniformly distributed very fine precipitate and from the chemical composition of alloys which referred in table (2)the copper (cu) is the main element in alloy 2024 t351 gives substantial increases in strength, permits precipitation hardening [13]. the fusion zone of mig welded joints for 6061-t651 and 2024-t351 shown in fig. (2) specimens (c,d) contain dendritic structure. the heat input fuses the base metal and filler metal to generate a zone with a composition that is in different from that of the base metal excess silicon in composition of wire filler is found to be beneficial for increasing the ductility of the welded structure. the spacing of weld region is wider in mig joint and as result of the increase in welding heat of the base metal and fast cooling of molten metal segregation appear. the mechanical tested results of all specimens in this study was listed in table (7) .include the yield strength, uts and elongation, bending force and macro hardness as compared with that of the base metal .table (3) the alloy 2024-t351 in un welding and welding conditions has better mechanical properties than the 6061t651 because of copper effected which increases in strength. these alloys using mig welding process evidence the difference in the microstructure and contributes to reduced mechanical properties and poor elongation observed during testing. mig welding process required high temperature for fusion, the haz region was large as well as and the subsequent melting and solidification that occur, voids are common defects found in fusion welds which contributed in that decay . the fracture surface section of tensile test specimens is shown in figure (4). the location of the failure for welded specimens after all mechanical test was found mainly along the haz region, they had failed at the weld metal with sudden fracture without reduction in area or necking. but un welded specimens were failed near the center line of the specimen. bending test results show that the bending load was reduced as compared with that of the base alloy but did not show any crack in the weld joints. the bend test showed fig.(8) that joints welded in all welding conditions were very brittle and subjected of very low bend angle without cracks ,specimens (c,d ) gives a lower bending force comparing with un welded alloys that goes with [14, 15, and 16], while bending in dissimilar specimens (e,f) has a slightly better bending result than similar joints. when comparing bending and tensile results of sample (e, f) it shows that sample (e) gives better results because of the welding angle preparation, where v shape angle contributed of heat input distribution causing a homogeny in microstructure compared to sample (f). table (7) shows the hardness values of the specimens, in general it was reduced as compared with the base alloy. the minimum hardness value was recorded in sample (c),where hardness in weld metal area was about (82 hv) and in the haz was about (100 hv), this value was larger than in the weld metal but lower than of the base alloy which is about (130hv)fig. (9), this reduction in hardness occurs due to high heat nawres jabar nasser al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 121128 (2016) 127 input and grain growth in this region, it can be observed that all specimens hardness profile have the same hardness distribution in different values. 4. conclusions 1higher heat input in the mig process has reverse effects on the mechanical properties of the welded alloys . 2-the maximum tensile strength of the welded joint is (200mpa) compared to (323 mpa) of the base alloy, i.e., the decay of strength about (40%). 3-hardness value is affected by the amount of the heat input during the welding process. 4the base metal has high tensile strength compared with the dissimilar materials welding. 5-it has found that the fracture occurred on the side of the aluminum alloy 6061 -t6 compared with that of aluminum alloy 2024-t3. 5. references [1] a. s. vagh1, s. n. pandya,” influence of process parameters on the mechanical properties of friction stir welded aa 2014-t6 alloy using taguchi orthogonal array”, international journal of engineering sciences & emerging technologies, volume 2,issue 1, pp: 51-58 april 2012. [2] benachour m., hadjoui a., benguediab m.,"heat treatment effect on fatigue crack growth" ,3rd international conference on integrity, reliability and failure, porto/portugal, 20-24 july 2009 . [3] klas weman ,"welding process handbook", cambridge, england, 2003. [4] s. jannet, p.k. mathews, r. raja, “comparative investigation of friction stir welding and fusion welding of 6061-t6 and 5083-o aluminum alloy based on mechanical properties and microstructure”, journal of achievements in materials and manufacturing engineering, vol. 6, issue 2, december 2013. [5] marek st. weglowski, adam pietras, aleksandra weglowska,” effect of welding parameters on mechanical and microstructural properties of al 2024 joints produced by friction stir welding”, journal of kones powertrain and transport, vol. 16, no. 1, 2009. [6] nazar abdulwadood1, burak sahin1, nihat yildirim” effect of welding parameters on the mechanical properties of dissimilar aluminum alloys 2024-t3 to 6061-t6 joints produced by friction stir welding” niğde üniversitesi mühendislik bilimleri dergisi, cilt 3, sayı 1, (2014), pp.25-36. [7] aendraa azhar abdul aziz ,”effects of different fillers on microstructure and tensile properties of welded aa6061-t6 “,key engineering materials vols. 462-463 (2011) pp 1189-1193. [8] mustafa kemal kulekci,” experimental comparison of mig and friction stir welding processes for en aw-6061-t6 (al mg1 si cu) aluminum alloy”, the arabian journal for science and engineering. 35: 2006, pp.321330. [9] jatinder gill, jagdevsingh, “effect of welding speed and heat input rate on stress concentration factor of butt welded joint of is 2062 e 250 a steel” international journal of advanced engineering research and studies e-issn2249–8974 ijaers/vol. i/ issue iii/april-june, 2012/98-100 [10] metals handbook, vol.2 properties and selection: nonferrous alloys and specialpurpose materials, asm international 10th ed. 1990. [11] annual book of astm standards, standard practice for calculation of corrosion rates and related information, g102-89, vol. 03.02,2004. [12] t senthil kumar, v balasubramanian, m y sanavullah,“influences of pulsed current tungsten inert gas welding parameters on the tensile properties of aa 6061 aluminum alloy”,. materials and design 28 (2007) 2080-2092. [13] m r ahmad, m a bakar, “effect of postweld heat treatment on the mechanical and microstructure properties of aa6061 joints welded by the gas metal arc welding cold metal transfer method”, materials and design 3. [14] p. cavaliere, r. nobile, f. w. panella anda. squillace, "mechanical and microstructural behavior of 2024-7075aluminum alloy sheets joined by friction stir welding", international journal of machine tools and manufacture 46, september 2005, pp. 588-594. [15] muafaq mehdi salih, "studying the effect of joint design, angle and heat treatment on mechanical properties of the aluminum alloy weldments (7020-t6) by mig process", master thesis, technical college/baghdad, november 2005. [16] s. missori and a. sili, "mechanical behavior of 6082-t6 aluminum alloy welds" metallurgical science and technology, vol. 18, 2000, pp.12-18. �� 3، ا���د��12 � ا���ارز�� ا������� ا��� � ��رس ��ر ���� �� ،2016( 121128( 128 �+ ���"* ا(�����م )�� (mig)���'ت ���م ا�$�س ا� ��#�"� ا���اص ا��� ��� �� (t351, 6061-t651 2024)ا��-,�#�� ��ر ������رس �� ��اد ���� ا���������� � � nawresjabaar@yahoo.com: ا�$!#� ا"����!و� ا��'�� ��ز &.4 ا��3اص ا�)��������1$�*( �0! ��)�/.�, +$�*( ا"�)���م &� #��ف��� �� ا�)6)*����ا�)���ا�$6> ا�4 ���ن :�/�! ط!#8��6م ا��8س ا���! وھ� ).��6-).��6و�0! ا�h ا��3اص ا�)��������.1$�*( ا��f: <�g), ا�$6> ا�!اء +.1.�, ا���dرب ا��6061-t6 �8�� -��8 ، t3٢٠٢٤-ھ)� ���د��6�tq, �, ا�1$�*( ا&jه �.�k6ل &.4 وjqت ا�od ا�.�6م &.4.وا��6� وا�$��ا�)m*�kn ، -#!�d ا��l و ا�jkدة"�� -�$u��: 200)*100*8( h.� �����+��3ام +.( ��6م ووq.اn!ى ��xt ا"���د ��ون زاو g(v)!ف در�٧٠ ��8ارھ� &)v زاو#:�f6!#�, ��وا�gة -#٤٠٤٣ er -#�(g ر��u ن�uوا"ر -.qا�� �.n ,� �uا�.�6م وا��� -�.(& �����ا+] ��k6\ لjn ,� ز �, ا����ب��� x-ray radiography -#ار!g -.���� ]#!ا� � &�� در�g!ارة*��!�u ن!\ �\ -.q�31, ا��: ]�(f: 170 �������ف ازا�ا���دات ا�.�6م �اءدر��_�#�)�ة �h/ -&�+ ^k ا��$!#� . !�f6: h: �lر ا��$�nت ا�.�6م وا�)� &���ت اjqا���8+�-�, و -tqن ا"+�س و\` ا�)�ا� astm17500 � astm (eو\` ا�)�اtqو�au( &���ت ا�n$�را��6 �!ض \m6 ا�$��ا�)�d!#�)��ط` ا�.�6م وا�)��ن (190-92� v8qو h���: ,� !�f6: ا�!اء &).��ت h/ -����& دةjq ر�$�nدة ,ا"+�س وا�!ي اjqو -8�d د����ا�.�6م &.4 ا��3اص ا�)��� !�/e: ن ا"+�س . �$��ن��(���و�.1$�*( �0! اظ�!ت ا����*f ا��t3ض \� ا��3اص ا�)��������.����ت ا�).��6��8ر� � ��]8ا��+j �.����ت ا�� ا��)�/.�i ا�h��$1 ا"+�س \ vltا� id�� 6!ارةوان���� ا�)�]8ا�)��/!ة \ vltت ا�).��6\�8 ظ�! ا������ . 7284 al-khwarizmi engineering journal,vol. 11, no. 3, p.p. integral sliding mode control design for electronic throttle valve shibly ahmed al *,**,***department of (received abstract one of the major components in an automobile engine is the throttle valve part. it is used to keep up with emissions and fuel efficiency low. design a control system to technology. the non-smoothness nonlinearity in throttle valve model are due to the friction model and the nonlinear spring, the uncertainty in system parameters and non designing a throttle plate controller. in this work, the theory of the integral sliding mode control (ismc) is utilized to design a robust controller for the electronic throttle valve (etv) system. from the first the nominal system model, this model is not affected by system parameters uncertainty and the non nonlinearities. this is a consequence of applying the integral sliding mode control. first is the nominal control which is used to control the nominal system, while the second is a discontinuous part which is used to eliminate the effects of the parameters uncertainty and the non these features for the ismc are proved mathematically and demonstrated numerically via seven numerical simulations and for different desired trajectories. the simulation results clarify that for different system parameters, the etv behaves as a nominal system. this enables to freely and precisely select the system response characteristics and the time required for the throttle angle to reach the desired value. moreover the ability to deal with the chattering problem is demonstrated through the worked simulation tests, where the chattering is eliminated via approximating the signum function by arc tan function. keywords: electronic throttle valve, nonlinear spring model, integral sliding mode control, non 1. introduction one of the key components in an automobile engine is the throttle valve part. throttle valve consists of a throttle plate, a motor causes the plate to rotate in angular position and return spring. the joint between the motor and the throttle plate is considered rigid. the opening angle of a throttle plate allows the air to flow to the engine. its function is to adjust the air khwarizmi engineering journal,vol. 11, no. 3, p.p. 7284 (2015) integral sliding mode control design for electronic throttle valve system shibly ahmed al-samarraie* alaq sabah badri** mustafa h. mishary*** *,**,***department of control and systems engineering/ university of technology *email: dr.shiblyahmed@yahoo.com **email: alaqsabah@yahoo.com ***email: albmustafa@yahoo.com (received 13 august 2014 ; accepted 18 may 2015) one of the major components in an automobile engine is the throttle valve part. it is used to keep up with emissions and fuel efficiency low. design a control system to the throttle valve is newly common requirement trend in automotive smoothness nonlinearity in throttle valve model are due to the friction model and the nonlinear spring, the uncertainty in system parameters and non-satisfying the matching condition are the main obstacles when in this work, the theory of the integral sliding mode control (ismc) is utilized to design a robust controller for the electronic throttle valve (etv) system. from the first instant, the electronic throttle valve dynamics is represented by the nominal system model, this model is not affected by system parameters uncertainty and the non nonlinearities. this is a consequence of applying the integral sliding mode control. the ismc consists of two part; the first is the nominal control which is used to control the nominal system, while the second is a discontinuous part which is used to eliminate the effects of the parameters uncertainty and the non-smooth nonlinearities fro these features for the ismc are proved mathematically and demonstrated numerically via seven numerical simulations and for different desired trajectories. the simulation results clarify that for different system parameters, the etv as a nominal system. this enables to freely and precisely select the system response characteristics and the time required for the throttle angle to reach the desired value. moreover the ability to deal with the chattering problem is the worked simulation tests, where the chattering is eliminated via approximating the signum electronic throttle valve, nonlinear spring model, integral sliding mode control, non one of the key components in an automobile throttle valve consists of a throttle plate, a motor causes the plate to rotate in angular position and return joint between the motor and the throttle plate is considered rigid. the opening angle of a throttle plate allows the air to flow to he engine. its function is to adjust the air–fuel ratio during combustion by changing the opening angle of the valve plate, through which there exists airflow. engine efficiency and emissions are affected by the control of the throttle plate, in particular its angular position. depending on the current engine load, the angular position must track a trajectory as determined by the accelerator [1]. the electronic throttling valve is shown in figure (1). al-khwarizmi engineering journal (2015) integral sliding mode control design for electronic throttle valve alaq sabah badri** of technology one of the major components in an automobile engine is the throttle valve part. it is used to keep up with emissions the throttle valve is newly common requirement trend in automotive smoothness nonlinearity in throttle valve model are due to the friction model and the nonlinear ing condition are the main obstacles when in this work, the theory of the integral sliding mode control (ismc) is utilized to design a robust controller for the instant, the electronic throttle valve dynamics is represented by the nominal system model, this model is not affected by system parameters uncertainty and the non-smooth the ismc consists of two part; the first is the nominal control which is used to control the nominal system, while the second is a discontinuous part which smooth nonlinearities from system model. these features for the ismc are proved mathematically and demonstrated numerically via seven numerical simulations and for different desired trajectories. the simulation results clarify that for different system parameters, the etv as a nominal system. this enables to freely and precisely select the system response characteristics and the time required for the throttle angle to reach the desired value. moreover the ability to deal with the chattering problem is the worked simulation tests, where the chattering is eliminated via approximating the signum electronic throttle valve, nonlinear spring model, integral sliding mode control, non-smooth model. ratio during combustion by changing the opening angle of the valve plate, through which there exists airflow. engine efficiency and emissions are affected by the control of the throttle plate, in its angular position. depending on the current engine load, the angular position must track a trajectory as determined by the accelerator [1]. the electronic throttling valve is shown in shibly ahmed al-samarraie al-khwarizmi engineering journal, vol. 11, no. 3, p.p. 110 (2015) 73 fig. 1. electronic throttle valve [2]. the electronic throttle valve is an electromechanical system with a dc motor as the actuating torque provider. due to the presence of the non-smooth nonlinearities in the electronic throttle valve system model and the uncertainty in system model parameters the objective of designing a successful controller is a challenging problem. moreover these nonlinearities and the uncertainty in system model do not lie in the control input channel which adds another problem named as the matching condition. many authors used the sliding mode control theory for controlling the throttle control system. all of them overcome the main problem (model nonlinearity) using sliding mode control theory as a robust tool with respect to uncertainty and nonlinearities in system model. due to the existence of nonlinearities including stick–slip friction, backlash, and a discontinuous nonlinear spring, the sliding mode control theory is utilized to design a robust controller that will force the throttle angle to follow the desired trajectory [3]. mercorelli [1] show the robustness of the tracking the desired angle, is addressed using a minimum variance control approach. this paper presents feasible real-time self-tuning of an approximated proportional derivative pd regulator. the saturation function for the proportional and the integral terms in the control law was used by al-samarraie [3] to force the state to slide along the switching manifold. the benefit of nonlinear integral term is to remove the chattering and to minimize the steady state error that happened due to the existence of the external disturbances. al-samarraie and abbas [4] show the effectiveness of using a nonlinear pid controller to force the throttle angle to track the desired reference. the result showed the ability of the nonlinear pid controller to work in the complete system model without simplification and showed that the controller is robust to the variations of system parameters. an observer-based sliding-mode controller with specific transient response for the etv system was designed by nakano et. al., [5]. by using a function-augmented sliding hyper-plane, it is ensured that the output tracking error converges to zero in a finite time. based on a dynamic lugre model to represent friction effects, witty et. al., [6] developed a dynamic model for an electronic throttle valve. an adaptive pulse controller is applied to achieve precise throttle positioning. horn et. al., [7] use two control strategies, the integral sliding-mode controller as well as the super-twisting algorithm, that, once tuned, they lead to accurate tracking interpretation over the whole range of process. a harmony search algorithm-based fuzzy-pid controller for electronic throttle valve was used by wang et. al., [8] to improve the responsiveness of etc. the controller gains are identified by using fuzzy rules. the model of the etv is improved and the discrete-time sliding mode controller together with the sliding mode observer is designed ozguner et. al., [9], to control the etv which show the successful rejection of the parameter uncertainty and external disturbance. dagci et. al., [10] recover non-smooth nonlinearities, stickslip friction, a nonlinear spring and gear backlash, to design robust controller to control the etv. pan et. al., [11] utilize a variable structure (vs) controller based on backstepping approach and a sliding mode observer with equivalent control to design a controller for the etv. it has been proved that in spite of existing non-smooth nonlinearities and unmatched parameter uncertainty the (vs) controller with the observer guaranteed accurate tracking to reference angle [11]. the main challenging problems in designing a controller for the electronic throttle valve are; a) the non-smooth nonlinearity in its model due to the friction model and the nonlinear spring, b) the uncertainty in system model parameters and c) the electronic throttle valve model does not satisfy the matching condition. the first and second problems can be solved via the sliding mode control method, since it can deal with these types of non-smooth nonlinearity in affecting system behavior. the third problem which is frequently arises in the electromechanical system where the uncertainty in system model and the disturbances does not appear in the control channel. the performance of the etv control system is the main goal behind the works presented above. by shibly ahmed al-samarraie al-khwarizmi engineering journal, vol. 11, no. 3, p.p. 110 (2015) 74 performance we mean the dynamic characteristics of the throttle angle response where it is required to reach the desired value without overshot and with minimum time. to do that the integral sliding mode controller is utilized in this work to precisely force the throttle angle to follow the desired value with desired dynamic characteristics from the first instant and desired time period required to reach the reference value. 2. mathematical model the mathematical model for the electronic throttle valve which considered in the present work is taken from reference [11]. in terms of the valve plate position θ, the rotor angular velocity ω, and the current i induced through the dc motor windings, the electronic throttle valve mathematical model is given by [11]; � �� = �� � �� � = − �������� + ������ � − ���� ��� � − ���� ��������� = − ��� − �� � + � !"# "$ …(1) where u is the input voltage to the dc motor, t&�ω� and t'(�θ� are the stick–slip friction torque and the nonlinear spring torque respectively. the frictional torque and the nonlinear spring torque are plotted in figs, (2) and (3) respectively and defined mathematically as follows [11]; ��� � = ) *�, > 0 0, = 0 −*�, < 0 � = *� /01� � …(2) and ������ = 2 3 + 4 �� − �5� �6 �5 < � < �789−3 −4 ��5 − �� �6 �7:; < � < �5 � = 4 �� − �5� + 3 /01�� − �5� …(3) fig. 2. coulomb friction [11]. fig. 3. nonlinear spring [11]. the physical parameters that appear in the mathematical model are defined in table (1). table 1, etv parameters [11]. parameters definition � gear ratio of the intermediate gear to the pinion gear � � sector gear ratio to the intermediate gear <=5= the total etv system damping >=5= the total etv system inertia �= motor torque constant �? motor back emf constant @ motor inductance a motor resistance *� positive constant in coulomb friction 3 spring offset 4 spring gain 4� spring limit stop gain �789 spring maximum position �7:; spring minimum position �5 spring default position to write the etv model in state space form, define b = � , b� = �� = �� � �� , and bc = �. accordingly the etv model, as given in equation (1), is written as follows; � b� = b� b�� = d� �b − b 5� + d��b� + d�cxc−µ/01�b�� − f/01�b − b 5� b�c = dc�b� + dccbc + gc h …(4) where the state space model parameters are d� = �ij�ik���� 4 , d�� = − �������� , d�c = �ij�ik������ , µ = �ij�ik���� *� , f = �ij�ik���� 3, dc� = − ����ij�ik , shibly ahmed al-samarraie al-khwarizmi engineering journal, vol. 11, no. 3, p.p. 110 (2015) 75 dcc = − �� , and gc = �. for these parameters, the maximum and minimum values are given in table (2) [2]. table 2, the maximum and minimum etv parameters values [2]. lmnmopqpnr ostsomu vmuwp omxsomu vmuwp wtsqp d� −69 −95 1//� d�� −32 −54 1// d�c 242.424 250 b. / /cdd. e04� dc� −20 −25 b. / /cdd.h dcc −1300 −2125 ω/f gc 1000 1250 1/f f 143.5 157 cdd//� h 57 76 cdd//� �5 0.095 0.095 cdd to simplify the etv model, the motor inductance l is ignored (i.e., by considering l ≈0). accordingly the throttle valve system model in equation (10) (4) is reduced to a system with lower dimension as can be noted in the following steps: k lmn b�c = k8mklm n b� + k8mmlm n bc + , k lmn = @ ∴ 0 ≈ k8mklm n b� + k8mmlm n bc + for @ ≈ 0 where k8mklm n and k8mmlm n are finite values since gc occurs in both dc� and dcc. now solving for bc yields: bc = −k8mk8mmn b� − k lm8mmn …(5) substituting the value of bc from equation (5) into equation (4), yields: �b� = b� b�� = −d �b − b 5� − d�b� + g −h/01�b�� − f/01�b − b 5� p…(6) where d = −d� , d� = −qd�� − d�c k8mk8mmnr and g = −d�c k lm8mmn . by writing equation (6) as a nominal and perturbation term, we get; �b � = b� b�� = −d ;�b − b 5� − d�;b� + g; + ds …(7) where the subscript 1 refers to the nominal parameters values and: d = −∆d �b − b 5� − ∆d�b� + ∆g −h/01�b�� − f/01�b − b 5� …(8) is the collection of the non-smooth nonlinearity and the uncertainty in system model. namely it consists of µ/01� � + f/01�b − b 5� as nonsmooth discontinuities due to coulomb friction and nonlinear spring and ∆d �b − b 5� +∆d�b� + ∆g is due to uncertainties in system parameters. in addition the model parameters related to their nominal values by the following inequalities; |d − d ;| = |∆d | < v8j, |d� − d�;| = |∆d�| < v8k , |g − g;| = |∆g| < vl , |f − f;| = |∆f| < vw , xµ − µ;x = |∆µ| < vµ in these inequalities v� � represent the bound for maximum uncertainty for the parameters. the parameters of equation (6) are given in table (3) below with maximum uncertainty v for each of them. table 3, etv parameters values in equation (6). ydcd4z{zc/ 1d4z/ |}4�1d~ bd~ z v d1 82 13 d2 46.54 12.26 g 177.2 63.2 f 150.25 6.75 h 66.5 9.5 the throttle valve system model given in equation (6) is a second order system and will be used later in designing an ismc that will force the state to track a certain desired throttle angle (system output). 3. integral sliding mode control the major advantage of sliding mode is low sensitivity to plant parameter variations and disturbances which eliminates the necessity of exact modeling. sliding mode control enables the decoupling of the overall system motion into independent partial components of lower dimension and, as a result, reduces the complexity of feedback design [13]. sliding mode control implies that control actions are discontinuous state functions which may easily be implemented by conventional power converters with “on-off” as the only admissible operation mode. due to these properties the intensity of the research at many scientific centers of industry and universities is maintained at high level, and sliding mode control has been proved to be applicable to a wide range of problems in robotics, electric drives and shibly ahmed al-samarraie al-khwarizmi engineering journal, vol. 11, no. 3, p.p. 110 (2015) 76 generators, process control, vehicle and motion control. in the present, the nonlinear system is described by differential equations in an arbitrary 1-dimensional state space with a scalar control action: b� = 6�b, � with b ∈ ℛ;, 6 ∈ ℛ;, ∈ ℛ, and { denoting the time. the conditions that will ensure sliding motion may be obtained from geometrical considerations: the deviation from the switching surface / and its time derivative should have opposite signs in the vicinity of a sliding surface / = 0 (or sliding manifold) [12]. lim�→�� /� < 0 and lim�→�� /� > 0 or /∗ /� < 0 …(9) inequality in equation (9) is referred to as reaching or sliding condition. the control signal that will ensure sliding motion (satisfying sliding condition) is selected as a discontinuous function of the state as follows: �b� = 2 ��b� �6 / > 0 ��b� �6 / < 0� …(10) where the scalar functions ��b�, ��b� and /�b� are continuous and smooth, and ��b� ≠ ��b�. accordingly the sliding mode assumes to occur on the surface /�b� = 0. a serious obstacle for utilization of sliding modes in control systems is a phenomenon referred to as “chattering”. the term chattering describes the phenomenon of finite-frequency, finite amplitude oscillations appearing in many sliding mode implementations [12]. the chattering in sliding mode control system can be eliminated by using a smooth function in the control. the price for this elimination is a steady state error as proved in reference [14]. as a new sliding mode controller design the integral sliding mode control (ismc) seeks to eliminate the reaching phase by enforcing sliding mode throughout the entire system response [12]. in integral sliding mode the order of the motion equation is equal to the order of the original system rather than reduced by the dimension of the control input as in the conventional sliding mode design. for this reason, it is also named as the full order sliding mode. as a result, robustness of the system can be guaranteed starting from the initial time instant [12]. to derive the control law, consider the following dynamic system; b� = 6�b� + 0�b� + d�b, {� …(11) where b ∈ ℛ;, 6 ∈ ℛ;, 0 ∈ ℛ;× , ∈ ℛ and d ∈ ℛcollected the unmodeled dynamics, the nonsmooth nonlinearities and external disturbances. rewrite equation (11) in terms of certain and uncertain dynamics as follows: b� = 6;�b� + 0;�b� + ∆6�b� + ∆0�b� + d�b, {� …(12) where 6;�b�, 0;�b� and ∆6�b�, ∆0�b� are the nominal and the uncertain system dynamics in equation (11). in addition let the control law is redesigned to be = ; + � …(13) where ; is the nominal control used to stabilize the nominal system dynamics with the desired characteristics. the nominal system dynamics is : b� = 6;�b� + 0;�b� ; …(14) the discontinuous control � designed to reject the perturbation term in equation (12). the perturbation term and the design of the ismc are clarified in the following analysis; equation (12) can be written as : b� = 6;�b� + 0;�b� ; + 0;�b� � + v�b, � …(15) where v�b, � = ∆6�b� + ∆0�b� + d�b, {� is the perturbation term. the perturbation attributable to parameter variations, unmodeled dynamics, non-smooth nonlinearities and external disturbances and is assumed to fulfill the matching condition [12] i.e., v�b, � = 0;�b�v��b, � …(16) as a first step in ismc design procedure, the sliding variable /�b� is defined as: /�b� = /5�b� + �, /�b�, /5�b� & � ∈ ℛ , …(17) which consists of two parts: the first part /��b� may be designed as a linear combination of the system states, similar to the conventional sliding mode design; the second part � introduces the integral term and will be determined below. to apply the sliding condition in equation (9) /� is differentiated as follows; /� = �/5�b b� + �� = �/5�b �6;�b� + 0;�b� ; + 0;�b� � + v�b, �� + �� = ����9 �0;�b� � + v�b, �� + ����9 �6;�b� + 0;�b� ;� + �� by choosing (similar to the derivation of the integral sliding mode in [12]) �� = − ����9 �6;�b� + 0;�b� ;� …(18) /� becomes; shibly ahmed al-samarraie al-khwarizmi engineering journal, vol. 11, no. 3, p.p. 110 (2015) 77 /� = ����9 �0;�b� � + v�b, �� …(19) and accordingly the sliding condition becomes; / /� = / ����9 �0;�b� � + v�b, �� …(20) by selecting � as in the conventional sliding mode � = −e�b� /�01�/� …(21) then equation (20) becomes; / ∗ /� = / ����9 0;�b� � + / ����9 v�b, � , since / ∗ /�01�/� = |/|, then /∗ /� = −|/| ����9 0;�b� e�b� + / ����9 v�b, � ≤ −|/| ����9 0;�b� e�b� + |/| �����9 v�b, �� ≤ −|/| �����9 0;�b�e�b� − �����9 v�b, ��� ≤ −|/| �����9 0;�b�� �e�b� − ������ ��9,�������� ��9�   …(22) where it is assumed that �����9 0;�b�� > 0. the discontinuous gain e�b� that will make the inequality in equation (22) less than zero (sliding motion) is selected as follows; e�b� > ������ ��9,�������� ��9� or e�b� = e5 + ������ ��9,�������� ��9� , e5 > 0 …(23) where e5 is positive constant. since the right hand side of equation (19) is discontinuous due to �, the sliding variable / will reached the origin in finite time � [15] and the system dynamics then is in sliding motion. accordingly the system dynamics can be determined using the equivalent control method as follows; when /�{� = 0, ∀ { ≥�, /��{� = 0 too and with v�b, � satisfies matching condition in equation (16), the equivalent control can be determined from equation (19) 0 = ����9 �0;�b� � + v�b, �� ⇒ ¤0;�b� �¥¦§ = −v�b, � …(24) equation (15) with the equivalent control in equation (24) is reduced to the nominal system dynamics as given in equation (14) with a dimension equal to 1. for this reason, the ismc is named as the full order sliding mode because the dimension in equation (14) is equal to the dimension of the original system in equation (11). to eliminate the reaching phase, which is a special property for the ismc, the initial condition for � is selected such that the initial condition for the sliding variable / is zero. this means that the system dynamics is in sliding mode from the first instant. namely by selecting ��0� = −/5�0� we have /�0� = 0 and /�{� =0, ∀ { ≥ 0. the ideal control can now be selected as a continuous state feedback with the desired dynamic characteristics [12]. eventually the integral sliding mode control law is; � �� = − ����9 6;�b� − ����9 0;�b� ;, ��0� = −/5�0� / = /5 + � = ; − e�b� ∗ /�01�/� p …(25) 4. ismc design for electronic throttle valve in this section, an ismc is designed to the electronic throttle valve that taken into consideration the uncertainty in system model and the presence of a non-smooth nonlinearity and external disturbances. the nominal system for the reduced mathematical model (equation (6)) is given by; �b � = b� b�� = −d ;�b − b 5� − d�;b� + g; ;s …(26) where the sliding variable is defined as; / = b� + �, ��0� = −b��0� …(27) to determine the control law for the etv system we need to define and calculate the following according to equation (25); ����9 = ¤0 1¥, 6;�b� = ¨ b�−d ;�b − b 5� − d�;b�© ⇒ �/5�b 6;�b� = −d ;�b − b 5� − d�;b� 0;�b� = ª 0g;« ⇒ ����9 0;�b� = g; from equation (8) the perturbation term is v�b, � = ¨0d© = ¬ 0−∆d �b − b 5� − ∆d�b� + ∆g −h/01�b�� − f/01�b − b 5� ­ shibly ahmed al-samarraie al-khwarizmi engineering journal, vol. 11, no. 3, p.p. 110 (2015) 78 ⇒ ����9 v�b, � = ∆d �b − b 5� + ∆d�b� +∆g − h/01�b�� − f/01�b − b 5� ⇒ �����9 v�b, �� = |∆d �b − b 5� + ∆d�b� + ∆g − h/01�b�� − f/01�b − b 5�| ≤ |∆d ||b − b 5| + |∆d�||b�| + |∆g|| | + µ789 + f789 ≤ v8j|b − b 5| + v8k|b�| + vl| ; − e�b� ∗ /�01�/�| + µ789 + f789 ≤ v8j|b − b 5| + v8k|b�| + vl| ;| + vl�b� + µ789 + f789 ∴ e�b� = e5 + k l�n �v8j|b − b 5| + v8k|b�| + | ;| + vle�b� + µ789 + f789� then by solving for e�b� we get e�b� = k l�l���®n �e5 + k l�n �v8j|b − b 5| + v8k|b�| + vl| ;| + µ789 + f789�� …(28) in the next step the ideal control is designed as follows; first let z = b − b ¯ and z� = b� − b�¯ then the nominal model given in equation (26) becomes z° = −d ;�b − b 5� − d�;b� − b��¯ + g; ; …(29) where b ¯ and b�¯ are the reference angular position and reference angular velocity in state space, respectively. accordingly the nominal control is designed as: ; = k l�n 2d ;�b − b 5� + d�;b� + b��¯−± z − ±�z� s …(30) as a result, the nominal system error dynamics becomes; z° = −± z − ±�z�, ± , ±� > 0 …(31) the values of ± and ±� are assigned according to the required system dynamics characteristics. finally the ismc for the etv system is; ��� = ± z + ±�z� − b��¯, ��0� = −b��0�/ = b� + � = ; − e�b�/�01�/� p …(32) with e�b� and ; are as given in equations (28) and (30) respectively. the integral sliding mode control, as can be notedfrom equation (32), leaves the electronic throttle valve with the required system characteristics equation (30) from the first instant. note also that the sliding variable /5 can be chosen as a linear combinations of states but, however, it can be chosen in terms of the states that the control input acts through their channels. in the etv, the input exists in b� channel, accordingly we select /5 = b�. 5. simulation results the simulations which are presented below are classified into three category. each of them either explores the ismc abilities or explains and analyzes the integral sliding mode controller features. the simulations are based on the full order model as given in equation (4) and the ismc is as given in equation (32). also e�b� and ; are given in equations (28) and (30) respectively. let e5 = 0.2, while the system parameters, their nominal values and maximum uncertainties are all given in tables (2) and (3). note that the value of e5 is slected small in order to reduce the amplitude of the chattering induced in system response. for the nominal controller ;, ± and ±� are determined based on pole placement method. the poles are selected such that the throttle angle reaches the target without overshot as one of the main requirement in automotive industry. to this end, let the characteristic roots for the nominal system equation (31) are −35,−35, then ± =35� and ±� = 70. throughout the simulations the ability of the ismc are investigated in forcing the throttle valve plate angle to follow three different desired trajectories which are described as follows: trajectory a (traj.a): constant reference throttle angle �¯ = 70 dz0. trajectory b (traj.b) [3]: the reference angle is piecewise constant; namely shibly ahmed al-samarraie al-khwarizmi engineering journal, vol. 11, no. 3, p.p. 110 (2015) 79 �¯ = 5.44deg. 6}c 0 ≤ { ≤ 1 = 70 deg. 6}c 1 < { ≤ 2.5 = 25 deg. 6}c 2.5 < { ≤ 4 = 45 deg. 6}c 4 < { ≤ 5 trajectory c (traj.c): the reference angle is a periodic function given by �¯ = �π/180� ∗ µ30 + 3 ∗ sinq�2π3 � ∗ tr¹ in addition the initial conditions employed for all simulations are ��, �,� �� = �5.44°, 0,0�. 5.1. numerical simulation test 1: control system performance with different system parameters the first set of simulations in this simulation test is carried out with the following system parameters; d� = −84, d�� = −40, d�c = 244, h = 65, f = 153 dc� = −21, dcc = −1550, gc = 1100 note that the parameters values lie within the range of parameters as illustrated in table (2). figures. (4), (5) and (6) are the etv system time responses for each type of trajectories presented above. they clarify the ability of the ismc in forcing the throttle plate angle to follow the desired trajectory within an interval of time not exceeds 0.25 /z±. this time interval is related directly to the characteristic roots selected to the nominal system dynamics equation (31). fig. 4. throttle angle versus time (traj.a & 1st parameter set). fig. 5. throttle angle & its desired versus time (traj.b & 1st parameter set). fig. 6. throttle angle versus time (traj.c & 1st parameter set). the main objective for the designed controller is to regulate the sliding variable / to zero level in finite time. as a main feature of the ismc the sliding variable is equal to zero from the first instant i.e., / = 0, ∀{ ≥ 0. in fact, this is the ideal case where an infinite switching process is assumed. with a finite switching process around / = 0, the sliding variable oscillates around / = 0 with a certain bound as can be shown in figures (7), (8) and (9). this bound is function of the switching gain e�b� and the interval of time used for the simulation process. fig. 7. switching surface versus time (traj.a & 1st parameter set). shibly ahmed al-samarraie al-khwarizmi engineering journal, vol. 11, no. 3, p.p. 110 (2015) 80 fig. 8. switching surface versus time (traj.b & 1st parameter set). fig. 9. switching surface versus time (traj.c & 1st parameter set). it can be also noted that the sliding variable requires less than 0.005 /z±. to reach and stay very close to zero value. this is a direct consequence of ignoring the electrical system dynamics when designing the ismc. the control signal (in voltage) for the three trajectory types are shown in figures (10), (11) and (12). the figures show, for the sever case, where the throttle angle is opened to 70 ° and when considering maximum uncertainty in system model, its value is less than 15 voltage. note that the dark area in figure (10) represent the high switching process of the controller due to the discontinuity nature of the sliding mode control law (eq. (32)). fig. 10. control action (») versus time (traj.a & 1st parameter set). fig. 11. control action (») versus time (traj.b & 1st parameter set). fig. 12. control action (») versus time (traj.c & 1st parameter set). the second set of simulations in this simulation use the following system parameters; d� = −75, d�� = −47, d�c = 248,h = 72, f = 145 dc� = −23, dcc = −2000, gc = 1200 the aim of this simulation is to show that the system response is identical to system response for the first set of simulation demonstrate which represents the distinguished property for the integral sliding mode control theory. this property is clarified later in the numerical simulation 2. the etv system response for the trajectory types a, b and c are shown in figures (13), (14) and (15). these figures are very similar to those in figures (4), (5) and (6) since the nominal system dynamics are the same. fig. 13. throttle angle versus time (traj.a & 2nd parameter set). shibly ahmed al-samarraie al-khwarizmi engineering journal, vol. 11, no. 3, p.p. 110 (2015) 81 fig. 14. throttle angle & its desired versus time (traj.b & 2nd parameter set). fig. 15. throttle angle versus time (traj.c & 2nd parameter set). 5.2. numerical simulation test 2: integral sliding mode controller characteristics in this simulation, the characteristics of the ismc are analyzed where the trajectory type a is considered in this simulation and the parameters used for the simulation are the first set of parameters in the preceding simulation test. in the first test, the aim is to show that the etv system responses for trajectory a are identical for different system parameters (first and the second test in the first simulation test) as shown in figure (16). the etv system is accordingly invariant to the uncertainties in system parameters and to the non-smooth nonlinearities. fig. 16. throttle angle versus time (traj.a 1st & 2nd parameter set). representing the etv system by the nominal system dynamics from the first instant is main feature for system dynamics when using ismc. figure (17) shows the nominal system of equation (31) and the etv response for trajectory a where the curves appear very close to each other. fig. 17. throttle angle versus time (traj.a actual & nominal throttle angle). the final test, it is devoted to plot the time history for the two terms of the sliding variable b� and �. figure (18) shows that the term � is updated to maintain the sliding variable equal to zero. it can be deduced that the ismc use a dynamic sliding variable to eliminate the uncertainty and the disturbances affecting the system dynamic and leaves it nominal. fig. 18. terms of sliding variables (¼½,¾) versus time. 5.3. numerical simulation test 3:chattering problem when it is required to eliminate the chattering, the signum function which appears in the sliding mode control law is replaced by an approximate function. the arc tan function is used instead of the signum function as follows: /�01�/� ≈ �¿ tan� �ℎ ∗ /� …(33) where ℎ > 1 is a design parameter adjusted in such a way that the response resembles the sliding shibly ahmed al-samarraie al-khwarizmi engineering journal, vol. 11, no. 3, p.p. 110 (2015) 82 motion but in a continuous manner. the etv system is simulated with approximate signum function as in equation (33) for trajectory type a and the first set of parameters as in simulation test 1. figure (19) shows that the throttle valve response is very close to system response without approximation. the chattering in figures (20) and (21) is greatly reduced compared with these in figures (7) and (10). fig. 19. throttle angle versus time (traj.a signum & arc tan function). fig. 20. switching surface versus time (traj.a signum & arc tan function). fig. 21. control action (u) versus time (traj.a signum & arc tan function). 6. conclusions in this work, the integral sliding mode control theory is utilized to design a robust controller for the electronic throttle valve (etv) system. ismc has the ability to cancel the effect of disturbance and uncertainty from any dynamic system by partite the control into two part first the ideal (or nominal) control ; which is used to stabilize the nominal system dynamics with the desired characteristics and the second part is discontinuous control � which is designed to reject the perturbation term. the main results in this work, due to applying the ismc for the etv system, can be summarized as follows: 1. the robustness of the proposed controller has been proved for a bounded uncertainty in system parameters with the presence of a nonsmooth nonlinearity and external disturbances and validated via numerical simulations for different parameters values in numerical simulation 1. 2. the system response for different parameters (within the uncertainty bound) is identical. namely, the ismc eliminates the perturbation term and leaves the etv and behaves as a nominal system; irrespective to the presence of the uncertainty in system model and the effects of the non-smooth nonlinearities. although that this property is the main feature of the ismc via the equivalent control method it is also proved in simulation tests 1 and 2. 3. the chattering problem is solved by replacing the signum function with arc tan function as approximation. in spite of this approximation, the time required to reach the target is still nearly equal (with suitable value for h) as proved in simulations test 3. the simulation results show that the chattering is eliminated. 7. references [1] paolo mercorelli, "robust feedback linearization using an adaptive pd regulator for a sensorless control of a throttle valve", mechatronics vol. 19, no. 8, pp. 1211-1354, 2009. 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[6] carlos canudas de witty, ilya kolmanovsky, and jing sun, "adaptive pulse control of electronic throttle", proceedings of the american control conference arlington, june, 2001 [7] martin horn, anton hofer and markus reichhartinger, "control of an electronic throttle valve based on concepts of slidingmode control", 17âã ieee international conference on control applications san antonio, texas, usa, september, 2008. [8] hui wang, xiaofang yuan, yaonan wang and yimin yang, "harmony search algorithm-based fuzzy-pid controller for electronic throttle valve", neural comput & applic, 2013. [9] urnit ozguner, sulgi hong, and yaodong pan, "discrete-time sliding mode control of electronic throttle valve", proceding of the 4äåã ieee conference on decision and control orlando, florida usa, december, 2001. [10] oguz hasan dagci, yaodong pan, and umit ozguner, "sliding mode control of electronic throttle valve", proceedings of the american control conference anchorage, ak may, 2002. [11] yaodong pan, ümit özgüner and o˘guzhasan da˘gci, "variable structure control of electronic throttle valve", ieee transaction on industrial electronics, vol. 55, no. 11, november, 2008. [12] v. i. utkin, j. guldner, and j. shi, "sliding mode control in electro-mechanical systems", crc press. taylor & francis group, 2009. [13] andrei a. agrachev a. stephen morse eduardo d. sontag h´ector j. sussmann vadim i. utkin, "nonlinear and optimal control theory", springer-verlag berlin heidelberg, 2008. [14] shibly ahmed al-samarraie, "invariant sets in sliding mode control theory with application to servo actuator system with friction", wseas transactions on systems and control issue 2, vol. 8, april, 2013 [15] giorgio bartolini, leonid fridman, alessandro pisano and elio usai (eds.), "modern sliding mode control theory", springer-verlag berlin heidelberg, 2008 )2015( 7284، ���� 3، ا�� د11 ا���ارز� ا��� �� ا������� � � �� ا��د ا ���را�� 84 ����� ����� �ة %�$ ا���# ��"�! � ������ ا���! ���م �� �ا)�����0 �/�ري **ا�! �*�ح ري *+*� ا(� ا�) $����*** ا,:789& ا,56(234,4&/ا,$012ة وا,(+# ھ()'& %$#***،**،* dr.shiblyahmed@yahoo.com :ا,?0<) ا=,065و>;* alaqsabah@yahoo.com :ا,?0<) ا=,065و>;** albmustafa@yahoo.com :ا,?0<) ا=,065و>;*** ا��ــ�2ــ� tua, . 0?67> 9jv 8$46ى ا=>?9r97ت و ا=9q6%د g; ا'op6ك ا,4%4د<9jm 0?67م ا,a(k اc) ا,45j>9ت ا,0f8 ;g &$2h0ك ا,$92رة b2c <6# ا'a6)ا8@ xjw_ ا,h9qa^ ا,jz, &21]o(+84& >26:& و43د ا=956cك وا,(2jqw . t\9# >+9م ا,9jq, #5f6م ا,a(k 8] ا,z16j?9ت ا,c &7h9y)<5w ;g 9x(9234,4 ا,$92رات be?9ت رmatching condition ( #2jqw ()e &$2h(2# ا,(+9م وe)م 0d kbfwط ا,g &b\91j; %) uncertainty(وا,9a6<0 ، ا,g ;1]o; ا,4jد<_ ا,0<9`; k)a,9م اjq\ #5f6z, 012$j,ا. fj),ا k,g)8 ;z8956,012 ا$j,ام >+0<& ا(a6'ا _j7,ا اhھ ;g #w (ismc) [268 012$8 #2jq6,)robust (;<065و,iا k)a,9م اjq\ #5f6z, ( etv ,9jm _2xjw #w ،kم ا,k)a \(+9م ر<g 0>9a6,9\ 0rl6> = ;,9x8 ;`9; %2# ا,j(+84& وا,h9qa^ ا,o[21& ا9j6eدا b2c &>0+< k2?1w kze 8] ا,fz+& اjو. 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involves the joining of metals without fusion or filler materials. in this study, the effect of welding t351 joints produced by fsw was investigated. different ranges of welding parameters, as input factors, such as welding speed (6 speed (725 1235 rpm) were used to obtain their influences on the main responses, in terms of elongation, tensile strength, and maximum bending force. experimental measurements of design expert 8 experimental design software which was used to (rsm) models. mathematical model of responses, as functions of used welding conditions, were obtained and analyzed by anova variance to verify the adequacy of these models. the resultant quadratic models showed tha speed or welding speed increases, the tensile strength and elongation of the joint and then decrease more likely due to the occurrence of void defect. leads to increase the maximum bending force firstly to a maximum value and then decreases. however, the welding speed was found more significant than rotational speed. models and optimization with the experimental ones with confidence level of 95%. keywords: friction stir welding, doe, rsm, 1. introduction friction stir welding (fsw) is a solid joining technology invented at the welding institute (twi) in 1991. it has been proven to be a very successful joining technology for alloys. compared to the conventional welding processes, fsw can produce superior mechanical properties in the weld zone. this new technique is attracting more and more research interest [1]. the fsw process appears to offer a number of advantages over conventional fusion welding techniques, such as no need for expensive consumables such as filler wire and gas shields, ease of automation on simple milling machinery, khwarizmi engineering journal, vol. 11, no. 1, p.p. 5164 (2015) determination of optimum welding parameters for fsw aa2024-t351 al-rubaie* qasim abbas atiah zuhair altaher*** department of mechanical engineering / university of technology *e-mail: alrabiee2002@yahoo.com **e-mail: dr_qasim_uot@yahoo.com ***e-mail: zuhairsadeed@gmail.com (received 18 june 2014; accepted 15 december 2014) friction stir welding is a relatively new joining process, which involves the joining of metals without fusion or filler materials. in this study, the effect of welding parameters on the mechanical properties of aluminum alloys aa2024 t351 joints produced by fsw was investigated. different ranges of welding parameters, as input factors, such as welding speed (6 34 mm/min) and rotational to obtain their influences on the main responses, in terms of elongation, tensile strength, and maximum bending force. experimental measurements of main responses were taken and analyzed using design expert 8 experimental design software which was used to develop the response surface methodology models. mathematical model of responses, as functions of used welding conditions, were obtained and analyzed by anova variance to verify the adequacy of these models. the resultant quadratic models showed tha speed or welding speed increases, the tensile strength and elongation of the joint firstly increase to a maximum value due to the occurrence of void defect. increasing both welding speed and rotational speed leads to increase the maximum bending force firstly to a maximum value and then decreases. however, the welding speed was found more significant than rotational speed. a good agreement was found between the results of these experimental ones with confidence level of 95%. stir welding, doe, rsm, mechanical properties, modeling and optimization friction stir welding (fsw) is a solid-state joining technology invented at the welding institute (twi) in 1991. it has been proven to be a very successful joining technology for aluminum alloys. compared to the conventional welding processes, fsw can produce superior mechanical properties in the weld zone. this new technique is attracting more and more research interest [1]. the fsw process appears to offer a number of over conventional fusion welding techniques, such as no need for expensive consumables such as filler wire and gas shields, ease of automation on simple milling machinery, good mechanical properties of the resultant joint, and low distortion [1]. during the fsw process, the tool penetrates into the workpiece, and then moves along the joint line at a constant speed (see figure 1). the material in front of the rotating tool pin is plastically deformed and stirred back to the trail edge of the tool pin in the the tool serves three primary functions, that is, heating of the workpiece, movement of material to produce the joint, and containment of the hot metal beneath the tool shoulder. heating is created within the workpiece both by friction between the rotating tool pin and shoulder and by severe plastic deformation of the workpiece. the localized heating softens the material around the al-khwarizmi engineering journal (2015) determination of optimum welding parameters for fsw qasim abbas atiah** university of technology friction stir welding is a relatively new joining process, which involves the joining of metals without fusion or filler parameters on the mechanical properties of aluminum alloys aa202434 mm/min) and rotational to obtain their influences on the main responses, in terms of elongation, tensile were taken and analyzed using response surface methodology models. mathematical model of responses, as functions of used welding conditions, were obtained and analyzed by anova variance to verify the adequacy of these models. the resultant quadratic models showed that as the rotation firstly increase to a maximum value increasing both welding speed and rotational speed leads to increase the maximum bending force firstly to a maximum value and then decreases. however, the welding a good agreement was found between the results of these mechanical properties, modeling and optimization . good mechanical properties of the resultant joint, e fsw process, the tool penetrates into the workpiece, and then moves along the joint line at a constant speed (see figure 1). the material in front of the rotating tool pin is plastically deformed and stirred back to the trail edge of the tool pin in the welding. the tool serves three primary functions, that is, heating of the workpiece, movement of material to produce the joint, and containment of the hot metal beneath the tool shoulder. heating is created within the workpiece both by friction e rotating tool pin and shoulder and by severe plastic deformation of the workpiece. the localized heating softens the material around the samir ali amin al-rubaie al-khwarizmi engineering journal, vol. 11, no. 1, p.p. 5164 (2015) 52 pin and, combined with the tool rotation and translation, leads to movement of material from the front to the back of the pin, thus filling the hole in the tool wake as the tool moves forward. the tool shoulder restricts the metal flow to a level equivalent to the shoulder position, that is, approximately to the initial workpiece top surface. as a result of the tool action and influence on the workpiece, when performed properly, a solid state joint is produced, that is no melting. because of various geometrical features on the tool, material movement around the pin can be complex, with gradients in strain, temperature, and strain rate. accordingly, the resulting nugget zone microstructure reflects these different thermomechanical histories and is not homogeneous [1]. a lot of researches [2-7] has been already done towards understanding the effect of fsw process parameters on the material flow behavior, microstructure formation, tool design and mechanical properties of friction stir welded joints, but there is a few works on studying the influence of input factors on mechanical properties using design of experiments (doe) and response surface methodology (rsm) technique. in this investigation, an attempt has been made to determine the effect of fsw process parameters on mechanical properties (elongation, tensile strength, and maximum bending force) in al alloy (aa2024-t351). 2. experimental work 2.1. selecting the aluminum alloy and specimens preparation of plates the base material used in this investigation is 2024-t351 which was obtained from a local market with thickness of (3.2 mm). aa2024-t351 aluminum alloy is al-cu-mg grade alloy of 2xxx series heat treatable of medium strength alloys. a piece of this alloy was analyzed to find its chemical composition by spectro device, as shown in table 1 with the standard material according as astm b209m [8] and the standard mechanical properties of aa2024-t351 aluminum alloy, given in table 2. the base material cut into required size is (210 mm *110 mm *3.2 mm) by a power saw cutting convenient for conducting fsw, and the plate edge was ground to ensure that there is no gap between the two plates. 2.2. design and manufacturing of welding tools the design of the tool is the key to the successful application of the process to a greater range of material and over a wider range of thickness. fsw tool of square pin profile and straight cylindrical shoulder was used. the geometry and dimensions of the tool are pin rotational diameter of 5 mm, shoulder diameter of 15 mm and pin length of 2.7 mm, see figure 2. the friction stir welding tool was manufactured by cnc turning and milling machines, this friction stir welding tool was fabricated from tool steel labeled as x12m (density ρ = 7800 kg/m3, specific heat cp = 500 j/kg.oc and the thermal conductivity k = 40 w/m.oc). the tool heat treatment includes heating the metal to 1020°c for 30 min and then air cooling to room temperature, which gives a hardness of 58 hrc [9], its chemical composition is tabulated in table 3 together with the standard tool material. 2.3. selecting the optimum fsw process parameters to obtain high quality of friction stir welded joints with high mechanical properties, i.e., high welding efficiency, the main welding parameters (rotational speed and welding speed) must be selected to determine the effect of each parameter on the mechanical properties. the rotational and welding speeds were chosen, therefore the tool rotational speed (725 1235 rpm) and the welding speed (6-34 mm/min) were used (see table 4). the fsw tests were carried out on a vertical milling machine with a square butt joint configuration. all the welds were produced perpendicularly to the rolling direction for aluminum alloys. 2.4. welding procedure a plate was fixed at a predetermined location on the backing plate (which was a 280*280*25 mm steel plate) and clamped into place. this same location was used for all plates in this study. the tool was then positioned directly over the plunge location and the pin was brought into contact with the top surface of the workpiece, see figure 3. each tool plunges slowly between the two sheets that are required to be welded until the samir ali amin al-rubaie al-khwarizmi engineering journal, vol. 11, no. 1, p.p. 5164 (2015) 53 shoulder of the tool touches the sheet surface. the tool was then allowed to dwell for 30-40 sec to allow the shoulder to preheat the workpiece during welding. after the dwell, the tool began to traverse along the welding line with the selected tool. when a full weld has been made, the pilot hole will be welded over and the pin was parked above the weld. when the tool was parked, it was dragged, and a park hole was left, as shown in figure 4. 2.5. mechanical tests 2.5.1. tensile test tensile test was carried out on samples taken in a perpendicular direction to the welding to determine the tensile properties of the welding joints, see figure 5. the shape and dimensions of the transverse tensile specimens according to astm e 8m [10] are shown in figure 6. all tensile tests were carried out at room temperature and constant loading rate (5 mm/min) by a computerized universal testing machine (hydraulic tinius olsen), which has a maximum capacity of (1000 kn). then, the average of three specimens was taken to evaluate the tensile behavior of each welded joint. 2.5.2. bending test three point bending test was carried out to determine the maximum bending force of the welded joints. bending tests were conducted with former diameter equal to 30 mm. the shape and dimensions of the transverse bending specimens are (15.24 mm * 38.1 mm) according to astm e 190 [11]. the bending test was carried out at room temperature by a universal testing machine (hydraulic laryee testing machine). 3. response surface methodology (rsm) response surface methodology (rsm) is a collection of mathematical and statistical techniques that are used for empirical model building and analysis of problems, in which a response of interest is influenced by several variables, and the objective is to optimize this response [12]. it has been extensively used in different engineering applications and fields. rsm is important in designing, formulating, developing, and analyzing new scientific studying and products. it is also efficient in the improvement of existing studies and products. the application of rsm to design optimization is aimed at reducing the cost of expensive analysis methods (e.g., finite element method or cfd analysis) and their associated numerical noise. by careful design of experiments, the objective is to optimize a response (output variable) which is influenced by several independent variables (input variables). an experiment is a series of tests, called runs, in which changes are made in the input variables in order to identify the reasons for changes in the output response. the advantages of design of experiments, as reviewed by aggarwal and singh [13], are as follows: (1) numbers of trials are reduced. (2) optimum values of parameters can be determined. (3) assessment of experimental error can be made. (4) qualitative estimation of parameters can be made. (5) inference regarding the effect of parameters on the characteristics of the process can be made. the efficiency of rsm is significantly influenced by selecting the proper choice of experimental designs. the central composite design (ccd) is one of the most popular class of designs to fit response surfaces, building the second order (quadratic) regression model to predict the responses. also, the most important characteristics of ccd is the spherical or rotatability property, i.e., the variance of predicted responses is the same at all points that are the same distance from the design center. therefore, in the present research, rsm was utilized using ccd to establish predicted models for some responses (mechanical properties) as functions of input factors (welding speed and rotational speed) during fsw process of 2024t351 aluminum alloy using the optimum tool design. moreover, numerical optimization was used to optimize the input parameters to obtain maximum responses. 4. experimental design matrix the input parameters used in the whole experimentation were selected according to the practical experience and the limitations of the experimental measurements. these factors are given in table 4 with two levels. the experimental design used was the response surface methodology using a central composite rotatable design for 2² factors, with 5 central points and α = ±1.414. 13 runs were performed according to the experimental design matrix (5 samir ali amin al-rubaie al-khwarizmi engineering journal, vol. 11, no. 1, p.p. 5164 (2015) 54 center points). each parameter was used at different code levels of −1.414, −1, 0, +1, and +1.414, whereby each level used conformed to an actual value equivalent to the coded value. thus, the input parameters studied are welding speed and rotational speed. the experimental design matrix used for input parameters in terms of actual factors with the experimental values of elongation, tensile strength and maximum bending load is given in table 5. the software design expert 8 was used to develop the model. results of test runs are reported, as well as, the prediction models produced within a 95% confidence interval. 5. results and discussion 5.1. tensile and bending test results after carrying out the experiments, the welded joints were visually examined and the welds with good surface appearance were chosen and machined into the standard test specimens for the mechanical testing (according to astm e8m [10] for tensile test and astm e190 [11] for bending test). tensile and bending tests were carried out as shown in figures 7a, 7b, and 8. it should be noted that the testing values of tensile and bending for the base metal are (438 mpa) and (1520 n), respectively. 5.2. modeling of the elongation the average responses obtained for elongation, tensile strength and maximum bending load were used in calculating the models of the response surface per response using the least-squares method. for elongation prediction, a reduced quadratic model in coded terms was analyzed with backwards elimination of insignificant coefficients at an exit threshold of alpha = 0.1. some coefficients were removed in order to obtain a formula with actual factors rather than coded ones. the term removed was ab. this means that the interaction of welding speed and rotational speed term had no significant effect on the elongation. table 6 shows the statistical analysis of variance produced by the software for the remaining terms. the model is significant at 95% confidence. it is noted that the rotational speed (b), squared welding speed (a2), and the squared rotational speed (b2) terms are all significant, while the welding speed (a) term is not. the lack of fit test indicates a good model. this model illustrates that only the three terms (b, a2 and b2) have the highest impact on elongation. the final equation in terms of coded factors is : elongation = +4.12 0.016 * a + 0.61 * b 0.70 * a 2 1.25 * b2 …(1) and, the final equation in terms of actual factors is: elongation = -39.12769 + 0.28011 * welding speed + 0.079162 * rotational speed 7.04170e003 * welding speed2 3.86475e-005 * rotational speed2 …(2) looking at the normal probability plot (figure 9a) for the elongation data, the residuals generally that falling on a straight line implying errors, are normally distributed. also, according to figure 9b that depicts the residuals versus predicted responses for elongation data, it is seen that no obvious patterns or unusual structure, implying models are accurate. figure 9c exhibits that the contour graph of welding speed and elongation as a response. it is seen that the increase in both welding speed and rotational speed leads to increase the elongation. the increase in welding speed led to increase in elongation. the joint exhibits poor elongation at a lower welding speed of 10 mm/min owing to the larger heat generation. as the welding speed increases from 10 to 20 mm/min, the negative effects of thermal cycles on joint properties are weakened, leading to an improvement in elongation. between 20 and 30 mm/min, the elongation of the joints show a decrease with increasing welding speed due to the occurrence of void defect. also, the increase in rotational speed led to increase in elongation. it can be seen that the elongation of the joint increases with increasing the rotational speed from 800 rpm to 980 rpm. the reason for this can be explained as follows: increasing the rotational speed would extend the shoulder dominated zone over the plate thickness. since the material in this shoulder dominated zone is softer and easier to be stirred, extending this zone through the thickness enhances the stirring and consequently improves the elongation of the joints. however, when the rotational speed increases up to 1160 rpm, the elongation of the joint decreases because of the formation of void defect. figure 10 manifests the predicted actual elongation data versus the actual ones for samir ali amin al-rubaie al-khwarizmi engineering journal, vol. 11, no. 1, p.p. 5164 (2015) 55 comparison reason. while figure 11 shows the 3d graph of elongation as a function of welding speed and rotational speed. it can be noted that the increase of welding speed resulted in a slight increase in the elongation value, while the increase of rotational speed caused a higher increase in the elongation. this means that the rotational speed has the highest impact on the elongation value. in other words, the rotational speed is more significant than the welding speed in the elongation model. with increasing rotational speed for a fixed welding speed or increasing welding speed for a fixed rotational speed, the elongation of the joints firstly increased to a maximum value and then showed a decrease due to the occurrence of welding defects [6, 14]. 5.3. modeling of the tensile strength similarly, for tensile strength measurements, a reduced quadratic model in coded terms was analyzed with backwards elimination of insignificant coefficients at the exit threshold of alpha = 0.1. the term removed was ab for obtaining a formula with actual factors rather than coded ones. table 7 reveals the statistical analysis of variance (anova), and this model is significant at 95% confidence. the rotational speed (b), squared welding speed (a²) and the squared rotational speed (b²) terms are all significant, while the welding speed (a) term is not. this model indicates that these three terms have the highest impact on the tensile strength. the lack of fit test indicates a good model. the final equation in terms of coded factors is : tensile strength = +230.40 + 3.14 * a -16.91 * b 22.40 * a2 -27.35 * b2 …(3) the final equation in terms of actual factors is: tensile strength = -584.03137 + 9.27514 * welding speed + 1.56032 * rotational speed 0.22402 * welding speed2 8.44003e-004 * rotational speed2 …(4) the normal probability plot of residuals for tensile strength data shows that the residuals (errors) fall generally on a straight, and they are normally distributed. and, there are no obvious patterns or unusual structure, implying models are accurate. according to figure 12 for the contour graph, it can be noticed that the increase of both welding speed and rotational speed generally increase the tensile strength value. figure 13 depicts the predicted versus actual tensile strength data for comparison purpose. whereas, figure 14 reveals the 3d graph of tensile strength as a function of welding speed and rotational speed. it is seen that the increase in both welding speed and rotational speed leads to increase the tensile strength. the increase in welding speed led to increase in tensile strength. the joint exhibits poor tensile strength at a lower welding speed of 10 mm/min owing to the larger heat generation. as the welding speed increases from 10 to 20 mm/min, the negative effects of thermal cycles on joint properties are weakened, leading to an improvement in tensile strength. between 20 and 30 mm/min, the tensile strength of the joints shows a decrease with increasing welding speed due to the occurrence of void defect. also, the increase in rotational speed led to increase in tensile strength. it can be seen that the tensile strength of the joint increases with increasing the rotational speed from 800 rpm to 980 rpm. the reason for this can be explained as follows: increasing the rotational speed would extend the shoulder dominated zone over the plate thickness. since the material in this shoulder dominated zone is softer and easier to be stirred, extending this zone through the thickness enhances the stirring and consequently improves the tensile strength of the joints. however, when the rotational speed increases up to 1160 rpm, the elongation of the joint decreases because of the formation of void defect. with increasing rotational speed for a fixed welding speed or increasing welding speed for a fixed rotational speed, the elongation of the joints firstly increased to a maximum value and then showed a decrease due to the occurrence of welding defects [6, 14]. 5.4. modeling of the maximum bending force similarly, for maximum bending force measurements, a reduced quadratic model in coded terms was analyzed with backwards elimination of insignificant coefficients at the exit threshold of alpha = 0.1. the term removed was ab for obtaining a formula with actual factors rather than coded ones. table 8 reveals the statistical analysis of variance (anova), and this model is significant at 95% confidence. the welding speed(a), squared welding speed (a²) and the squared samir ali amin al-rubaie al-khwarizmi engineering journal, vol. 11, no. 1, p.p. 5164 (2015) 56 rotational speed (b²) terms are all significant, while the rotational speed (b) is not significant. this model illustrates that these three terms have the highest impact on the tensile strength. the lack of fit test indicates a good model. the final equation in terms of coded factors is : maximum bending force = + 1374.98 + 61.68 * a 20.39 * b 320.89 * a2 -322.80 * b2 …(5) the final equation in terms of actual factors is: maximum bending force = -9489.29985 + 134.52393 * welding speed + 19.41404 * rotational speed 3.20890 * welding speed2 9.96292e-003 * rotational speed2 …(5.6) the normal probability plot of residuals for maximum bending force data shows that the residuals (errors) fall generally on a straight, and they are normally distributed. and, there are no obvious patterns or unusual structure, implying models are accurate. according to figure 15 for the contour graph showing the interaction of welding speed and rotational speed, it can be noticed that the increase of both welding speed and rotational speed generally increase the maximum bending force value. figure 16 depicts the predicted versus actual maximum bending force data for comparison purpose. whereas, figure 17 reveals the 3d graph of maximum bending force as a function of welding speed and rotational speed. it is seen that the increase in welding speed leads to increase the maximum bending force. as indicated with the elongation and tensile strength models, it can be concluded that the maximum bending force is also smaller at the lowest and highest welding speed and rotational speed, whereas it is larger at (20 mm/min) welding speed and (980 rpm) rotational speed. 5.5. numerical optimization of elongation, tensile strength and maximum bending force the numerical optimization was provided by the design of experiment software to find out the optimum combinations of parameters in order to fulfill the requirements as desired. therefore, this software was used for this optimization, based on the data from the predictive models for three responses, elongation, tensile strength and maximum bending force, as a function of two factors: welding speed and rotational speed. elongation, tensile strength and maximum bending force are modeled with a quadratic model. to develop the new predicted models, a new objective function, named desirability which allows to properly combining all the goals, was evaluated. desirability is an objective function, to be maximized through a numerical optimization, which ranges from zero to one at the goal. adjusting its weight or importance may alter the characteristics of a goal, and the aim of the optimization is to find a good set of conditions that will meet all the goals. usually, the weights are used to establish an evaluation of the goal’s 3d importance when maximizing desirability function; in this work, weights are not changed since the three responses (elongation, tensile strength and maximum bending force) have the same importance and are not in conflict within each other. the ultimate goal of this optimization was to obtain the maximum response that simultaneously satisfied all the variable properties. table 9 lists the constrains of each variable for numerical optimization of the elongation, tensile strength and maximum bending force. according to this table, one possible run fulfilled these specified constrains to obtain the optimum values for elongation, tensile strength and maximum bending force, as given in table 10. it can be seen that this run gave desirability of 0.868. figure 18 shows the surface plot for desiability as a function of welding speed and rotational speed. figures 19,20 and 21 depict the optimum values of the elongation, tensile strength and maximum bending force, respectively. thus, it can be concluded from these figures that the desirability reaches the maximum value of 0.868 when the optimum value of elongation is 4.1 % (figure 19), the optimum value of tensile strength is 230.773 mpa (figure 20) and the optimum value of maximum bending force is 1377.83 n, as shown in (figure 21). 5.6. comparison of predicted results with experimental ones a comparison between the actual (with the optimum tool design) and predicted for elongation, tensile strength, and maximum bending force is shown in table 11. this table also exhibits the percentage error between the actual and predicted results of elongation, tensile strength, and maximum bending force. in addition, according to this table, it is shown a very samir ali amin al-rubaie al-khwarizmi engineering journal, vol. 11, no. 1, p.p. 5164 (2015) 57 good agreement between the actual results of the elongation, tensile strength, and maximum bending force and the predicted results obtained by doe and rsm technique. 6. conclusions the following conclusions have been made from the present investigation: • increasing both welding speed and rotational speed leads to increase the elongation and tensile strength up to 20 mm/min welding speed and 980 rpm rotational speed. the increase of welding speed resulted in a slight increase in the elongation and tensile strength, while the increase of rotational speed caused a higher increase in these two properties. this means that the rotational speed has the highest impact than welding speed on the elongation and tensile strength. • increasing both welding speed and rotational speed leads to increase the maximum bending force up to 20 mm/min welding speed and 980 rpm rotational speed. however, the welding speed was found more significant than rotational speed. • quadratic predicted models for elongation, tensile strength, and maximum bending force were obtained in terms of welding speed and rotational speed with 95% confidence level. • among the 13 experiments of experimental work, 20 mm/min welding speed and 980 rpm rotational speed gives better tensile strength (245 mpa), elongation (4.7), maximum bending force (1450 n). • from the numerical optimization, the optimum values of elongation, tensile strength, and maximum bending force were found to be (4.1%), (230.733mpa) and (1377.83 n), respectively with a desirability 0.868 at (21 mm/min) welding speed and (977 rpm) rotational speed. table 1, standard and experimental chemical compositions of aluminum alloy aa2024-t351 (wt%). wt% material si fe cu mn mg cr zn standard [8] ≤0.500 ≤0.500 3.800-4.900 0.300-0.900 1.200-1.800 ≤0.100 ≤0.250 experimental 0.121 0.265 3.800 0.511 1.370 0.009 0.134 table 2, standard and experimental mechanical properties of aluminum alloy aa2024-t351. property material бy (mpa) бu (mpa) el. (%) standard [8] ≥290 ≥435 ≥15 experimental 327 438 17.3 table 3, chemical composition of tool steel x12m [8]. element c si mn p s cr cu ni v standard [9] 1.800 2.400 ≤0.400 ≤0.600 ≤0.030 ≤0.030 12.000 15.000 ≤0.250 ≤0.500 ≤0.300 actual 1.870 0.278 0.270 0.009 0.001 12.440 0.079 0.200 0.023 table 4, levels of input parameters used with respective coding. factor unit low level (-1) high level (+1) -alpha (-1.414) +alpha (+1.414) welding speed mm/min 10 30 6 34 rotational speed rpm 800 1160 725 1235 samir ali amin al-rubaie al-khwarizmi engineering journal, vol. 11, no. 1, p.p. 5164 (2015) 58 table 5 experimental design matrix for both actual input factors and responses. standard no. run no. type of point welding speed (mm/min) rotational speed (rpm) elongation (%) tensile strength (mpa) maximum bending force (n) 1 3 factorial 10 800 1.1 206 673 2 13 factorial 30 800 1.5 206 838 3 6 factorial 10 1160 2.6 161 670 4 9 factorial 30 1160 2.5 172 787 5 1 axial 6 980 3.1 175 775 6 10 axial 34 980 2.8 185 790 7 2 axial 20 725 1.0 190 550 8 4 axial 20 1235 2.7 150 715 9 7 center 20 980 3.5 218 1330 10 8 center 20 980 4.7 245 1450 11 5 center 20 980 4.2 217 1350 12 11 center 20 980 3.7 231 1316 13 12 center 20 980 4.5 241 1435 table 6 anova analysis for response surface quadratic model (elongation, %). source sum of squares df mean square f value p-value prob > f model 16.01 4 4.00 19.62 0.0003 significant awelding speed 1.930e-003 1 1.930e-003 9.464e-003 0.9249 brotational speed 3.02 1 3.02 14.82 0.0049 a2 3.45 1 3.45 16.91 0.0034 b2 10.94 1 10.94 53.62 < 0.0001 residual 1.63 8 0.20 lack of fit 0.58 4 0.15 0.56 0.7077 not significant pure error 1.05 4 0.26 cor total 17.64 12 17.64 std. dev. 0.45 r-squared 0.9075 mean 2.92 adj r-squared 0.8612 c.v.% 15.49 pred r-squared 0.7552 press 4.32 adeq precision 12.044 table 7 anova analysis for response surface quadratic model (tensile strength, mpa). source sum of squares df mean square f value p-value prob > f model 10100.35 4 2525.09 20.08 0.0003 significant awelding speed 79.02 1 79.02 0.63 0.4508 brotational speed 2288.39 1 2288.39 18.20 0.0027 a2 3490.78 1 3490.78 27.76 0.0008 b2 5215.56 1 5215.56 41.48 < 0.0002 residual 1005.96 8 125.74 lack of fit 346.76 4 86.69 0.53 0.7255 not significant pure error 659.20 4 164.80 cor total 11106.31 12 std. dev. 11.21 r-squared 0.9094 mean 199.77 adj r-squared 0.8641 c.v.% 5.61 pred r-squared 0.7626 press 2636.86 adeq precision 11.335 samir ali amin al-rubaie al-khwarizmi engineering journal, vol. 11, no. 1, p.p. 5164 (2015) 59 table 8 anova analysis for response surface quadratic model (maximum bending force, n). source sum of squares df mean square f value p-value prob > f model 1.310e+006 4 3.275e+005 110.86 < 0.0001 significant awelding speed 30433.08 1 30433.08 10.30 0.0124 brotational speed 3329.39 1 3329.39 1.13 0.3194 a2 7.162e+005 1 7.162e+005 242.47 < 0.0001 b2 7.268e+005 1 7.268e+005 246.03 < 0.0001 residual 23631.56 8 2953.95 lack of fit 6931.56 4 1732.89 0.42 0.7924 not significant pure error 16700.00 4 4175.00 cor total 1.334e+006 12 std. dev. 54.35 r-squared 0.9823 mean 978.69 adj r-squared 0.9734 c.v.% 5.55 pred r-squared 0.9555 press 59333.04 adeq precision 21.628 table 9 constrains of each varaible for numerical optimization of elongation, tensile strength and maximum bending force. types of variables goal lower limit upper limit lower weight upper weight importance a: welding speed is in range 10 30 1 1 3 b: rotational speed is in range 800 1160 1 1 3 elongation maximize 1 4.7 1 1 3 tensile strength maximize 150 245 1 1 3 maximum bending force maximize 600 1450 1 1 3 table 10 optimal conditions used to obtain the maximum elongation, tensile strength and maximum bending force. no. welding speed (mm/min) rotational speed (rpm) elongation (%) tensile strength (mpa) maximum bending force (n) desirability 1 21 977 4.1 230.733 1377.83 0.868 selected table 11 comparison between the actual and predicted responses. welding speed (mm/min) rotational speed (rpm) elongation (%) tensile strength (mpa) maximum bending force (n) actual 20 980 4.7 245 1450 predicted 21 977 4.1 230.733 1377.83 % error 12.77 5.82 4.98 table 12 conversions for each of the units used in the present work. unit with si unit with u.s. customary (nonmetric) 1 mpa 145.038 psi 1 m 3.2808 ft 1 mm/min 0.05468 ft/s 1 n 0.2248 ibf samir ali amin al-rubaie fig. 1. schematic diagram of fsw fig. 2. design drawing for fsw tool (square pin with flat surface shoulder). fig. 3. welding backing plate and fixtures in use for fsw. fig. 4. welded sample explained welding start, and end of welded joint. end of welding line plunging of tool welding direction al-khwarizmi engineering journal, vol. 11, no. 1, p.p. 60 schematic diagram of fsw. design drawing for fsw tool (square pin welding backing plate and fixtures in use for fig. 4. welded sample explained welding direction, fig. 5. tensile and bending test specimens locations (all dimensions in mm). fig. 6. tensile test specimen (all dimensions in mm) astm (e 8m). fig. 7a. tensile test specimens before testing fig. 7b. tensile test specimens after testing end of welding line khwarizmi engineering journal, vol. 11, no. 1, p.p. 5164 (2015) tensile and bending test specimens locations tensile test specimen (all dimensions in mm) fig. 7a. tensile test specimens before testing. 7b. tensile test specimens after testing. samir ali amin al-rubaie al-khwarizmi engineering journal, vol. 11, no. 1, p.p. 5164 (2015) 61 fig. 8. bending test specimen after testing. fig. 9. modeling of elongation property: (a) normal probability plot for elongation (%) data, (b) residual versus predicted responses elongation (%) data, and (c) contour graph of elongation (%) as a function of welding speed and rotational speed. fig. 10. predicted versus actual elongation (%) data for comparison. fig. 11. 3d graph of elongation (%) as a function of welding speed and rotational speed. fig. 12. contour graph of tensile strength as a function of welding speed and rotational speed. design-expert® software elongation color points by value of elongation: 4.7 1 internally studentized residuals n or m al % p ro ba bi lit y normal plot of residuals -2.00 -1.00 0.00 1.00 2.00 1 5 10 20 30 50 70 80 90 95 99 design-expert® software elongation color points by value of elongation: 4.7 1 predicted in te rn al ly s tu de nt iz ed r es id ua ls residuals vs. predicted -3.00 -2.00 -1.00 0.00 1.00 2.00 3.00 0.00 1.00 2.00 3.00 4.00 5.00 design-expert® software factor coding: actual elongation design points 4.7 1 x1 = a: welding speed x2 = b: rotational speed 10 15 20 25 30 800 890 980 1070 1160 elongation a: welding speed b : r ot at io na l s pe ed 2 22.25 2.252.5 2.75 3 33 3.25 3.253.25 3.5 3.75 4 5 design-expert® software elongation color points by value of elongation: 4.7 1 actual p re di ct ed predicted vs. actual 0.00 1.00 2.00 3.00 4.00 5.00 1.00 2.00 3.00 4.00 5.00 design-expert® software factor coding: actual elongation design points above predicted value design points below predicted value 4.7 1 x1 = a: welding speed x2 = b: rotational speed 800 890 980 1070 1160 10 15 20 25 30 1 2 3 4 5 e lo ng at io n a: welding speed b: rotational speed design-expert® software factor coding: actual tensile strength design points 245 150 x1 = a: welding speed x2 = b: rotational speed 10 15 20 25 30 800 890 980 1070 1160 tensile strength a: welding speed b : r ot at io na l s pe ed 175 175180 180 185 185190 195 200 200 205 205 205 210 210 215 220 225 230 5 (a) (c) (b) samir ali amin al-rubaie al-khwarizmi engineering journal, vol. 11, no. 1, p.p. 5164 (2015) 62 fig. 13. predicted versus actual tensile strength data for comparison. fig. 14. 3d graph of tensile strength as a function of welding speed and rotational speed. fig. 15. contour graph of maximum bending force as a function of welding speed and rotational speed. fig. 16. predicted versus actual maximum bending force data for comparison. fig. 17. 3d graph of maximum bending force as a function of welding speed and rotational speed. fig. 18. 3d surface plot for desirability as a function of welding speed and rotational speed. fig. 19. the optimum value of elongation. fig. 20. the optimum value of tensile strength. design-expert® software tensile strength color points by value of tensile strength: 245 150 actual p re di ct ed predicted vs. actual 140.00 160.00 180.00 200.00 220.00 240.00 260.00 140.00 160.00 180.00 200.00 220.00 240.00 260.00 design-expert® software factor coding: actual tensile strength design points above predicted value design points below predicted value 245 150 x1 = a: welding speed x2 = b: rotational speed 800 890 980 1070 1160 10 15 20 25 30 160 180 200 220 240 260 t en si le s tr en gt h a: welding speed b: rotational speed design-expert® software factor coding: actual maximum bending force design points 1450 600 x1 = a: welding speed x2 = b: rotational speed 10 15 20 25 30 800 890 980 1070 1160 maximum bending force a: welding speed b : r o ta tio na l s pe ed 800 800 900 900 900 900 1000 1000 1000 1100 1200 1300 5 design-expert® software maximum bending force color points by value of maximum bending force: 1450 600 actual p re di ct ed predicted vs. actual 600.00 800.00 1000.00 1200.00 1400.00 1600.00 600.00 800.00 1000.00 1200.00 1400.00 1600.00 design-expert® software factor coding: actual maximum bending force design points above predicted value design points below predicted value 1450 600 x1 = a: welding speed x2 = b: rotational speed 800 890 980 1070 1160 10 15 20 25 30 600 800 1000 1200 1400 1600 m ax im um b en di ng fo rc e a: welding speed b: rotational speed design-expert® software factor coding: actual desirability 1.000 0.000 x1 = a: welding speed x2 = b: rotational speed 800 890 980 1070 1160 10 15 20 25 30 0.000 0.200 0.400 0.600 0.800 1.000 d es ira bi lit y a: welding speed b: rotational speed 0.8680.868 design-expert® software factor coding: actual elongation design points 4.7 1.0 x1 = a: welding speed x2 = b: rotational speed 10 15 20 25 30 800 890 980 1070 1160 elongation a: welding speed b : r ot at io na l s pe ed 2.0 2.02.5 3.0 3.03.0 3.5 4.0 5 prediction 4.1 design-expert® software factor coding: actual tensile strength design points 245 150 x1 = a: welding speed x2 = b: rotational speed 10 15 20 25 30 800 890 980 1070 1160 tensile strength a: welding speed b : r ot at io na l s pe ed 175 175 185 185195 205 205 205 215 225 5 prediction 230.773 samir ali amin al-rubaie al-khwarizmi engineering journal, vol. 11, no. 1, p.p. 5164 (2015) 63 fig. 21. the optimum value of maximum bending force. notation a welding speed b rotational speed cp specific heat k thermal conductivity greek letters ρ density α star point 7. references [1] rajif s. mishra and murray w. mahoney, “friction stir welding and processing”, wiley inc., 2007. [2] r. palanivel, p. mathews, n. muragan, and i. dinaharan, “effect of tool rotational speed and pin profile on microstructure and tensile strength of dissimilar friction stir welded aa5083-h111 and aa6351-t6 aluminum alloys”, journal of materials and design, vol. 40, pp. 7-16, 2012. [3] i. rani and r. marpu, “the effect of variation of tool geometry on friction stir welded aluminum alloysan experimental investigation”, international journal of mechanical engineering and robotics research, vol. 1, no. 1, pp. 91-98, 2012. [4] h. mohanty, d. venkateswarlu, m. mahapatra, p. kumar and n. mandal, “modeling the effects of tool probe geometries and process parameters on friction stirred aluminum welds”, journal of mechanical engineering and automation, vol. 2(4), pp. 74-79, 2012. [5] r. narsu and i. rani, “an experimental investigation of the effect of variation of tool geometry and optimization of process parameters on friction stir welded aluminum alloys”, international journal of research in aeronautical and mechanical engineering, vol. 1, issue. 7, pp. 261-266, 2013. [6] m. koilraj, v. sundareswaran, s. vijayan, and s. rao, “friction stir welding of dissimilar aluminum alloys aa2219 to aa5083optimization of process parameters using taguchi technique”, journal of materials and design, vol. 42, pp. 1-7, 2012. [7] p. prasanna, c. penchalayya, and d. rao, “optimization and validation of process parameters in friction stir welding on aa6061 aluminum alloy using gray relational analysis”, international journal of engineering research and applications (ijera), vol. 3, issue. 1, pp. 1471-1481, 2013. [8] standard specification for aluminum and aluminum alloy astm sheet and plate, astm b209m. [9] standard jis g 4404, alloy tool steel, material number 1.208, 1983. [10] standard test method for tension testing of metallic materials, astm e8m, 1988. [11] standard method for guided bend test for ductility of welds, astm e190, 1980. [12] montgomery, d. c., “design and analysis of experiments”, 5th edition, john wiley & sons inc., 2000. [13] a. aggarwal and h. singh, “optimization of machining techniques a retrospective and literature review”, sadhana, vol. 30, part 6, pp. 699-711, 2005. [14] huijie liu, huijie zhang, qing pan, and lei yu, “effect of fsw parameters on microstructural characteristics and mechanical properties of 2219-t6 aluminum alloy joints”, international journal of material forming, vol. 5, pp. 235-241, 2012 design-expert® software factor coding: actual maximum bending force design points 1450 600 x1 = a: welding speed x2 = b: rotational speed 10 15 20 25 30 800 890 980 1070 1160 maximum bending force a: welding speed b : r ot at io na l s pe ed 800 800 900 900 900 900 1000 1000 1000 1100 1200 1300 5 prediction 1377.83 � ا�ر���� ��� �� ا����� ���� 1، ا���د�11ا���ارز�� ا������� ا�� ،2015( 5164( 64 ا������� *�ا�(� ��!م (aa2024-t351))��'� ��!�&ت ا���!م ا��$!��� �#"! � ا������م �+!,-.� ا���/ ا �� ***زھ� ا�(!ھ **3!�2 "!س (�� *ا� *��� أ��� ��� ��� ا���������� ***،**،*�� ا�'�&%� ا�$��#�#"�� / ! � ا� alrabiee2002@yahoo.com: ا�-*,� ا+��$*و�)* dr_qasim_uot@yahoo.com: ا�-*,� ا+��$*و�)** zuhairsadeed@gmail.com: ا�-*,� ا+��$*و�)*** �� ا��& �ة � -��ً، و ا�:ي , $80م �/�م ا��%�دن 7�ون ا�5$�ام ا+�4��ر او ا��#اد ا�����1ا�0/�م ,�f) ھ:ه ا��را��، d� ا�$/a05��7 . bc ا+@$��?) ھ# =���0 �/�م " .,�c �/�م ا�a05 ا+@$��?)ا��l&�%& *�m�d n&)aa2024-t351 (*o7 �&#/0ت ا�0/�م =j0 ا�5#اص ا���������� � -�gh ا+����#م d ،ت ا�0/�مl&�%�� �p0$5& ت�,��� � ا�5$�ام &pq#7 ا�0/�م �=*� rs& ،ل�uإد r&34-6(=#ا mm/min (* ورا��� و ا��) rpm 1235-725(=� ا� ���o$�+ا ��+�7 ،� �h*ا+�$'��7ت ا� j0= ھ�*�m�d j0= و �4/0#ل j�w%ء ا����، و !#ة ا+�/yو&� ا��c& .d ت����! r�0/d ام و�� d� إ�5$! ��? ��-,*' �، و!#ةyو&� ا��c& ،���o$�l� ء���'�� �)design expert 8 ( �7�'$�lا�%j�w 7]�$%��ل z&��*7 ا�$��4� ا�$'*,-( ا+�/��4/0#ل =j0 ���ذج & ��/o ا�)rsm .( ذج ا�*,�_) �^�$'��7ت#���، ا+�$d ��?)،���o� إ�$/�4ل و r�0/d ا�yو&�ا��c& j�w%ءا���ف ا�0/�م ?�وال �`*و) و!#ةا+�/ n,�-d ا�� $%��0 ��7$%��لanova ذج����7�b��7 c 87,�دة �*=� ا�0/�م و ا� *=� ا��ورا���، 8d b��fداد . ���hl& n& bc/$0 ھ:ه ا� �'d��ا����ذج ا��*7%� ا� � و ا+�$���o ا��c& j�w= ���! jو&�yا��$d �m �,ا��وث ا�%�#ب ا�p*اf��d) ا�-@ g7 h!� .l? ان ز,�دة ��? n& �=*� دي وا� *=� ا�0/�مjd ورا����ا� ��!h ا+�/��ء ا�j ز,�دة !#ة$d �m j�w= ���! jاو+ً ا� j�w%ا&*. ا� n& n�, ���� و"� �7ن �*=� ا�0/�م �d#ن ا?�m�d *s*ا &n ا� *=�f، و&c ورا����و . ا� � zh�$� n�7 ھ:ه ا����ذج و ا+&l& ��0s ا��$�zh ا�%���0 �7 $#ى �" bfا#d � ).�cm)95% و" 151-137شنو واكو ويونس al-khwarizmi engineering journal,vol. 13, no. a study of land zoning using arcgis shno mustafa ali * college of engineering ** department of civil engineering ***faculty of (received https://doi.org/10.22153/kej.201 abstract this study is an approach to assign the land area of kilometers north of baghdad and 83 kilometers multi zones by using satellite image and arc map like what achieved in this paper will help and of it’s of a high interest point urban planning and economic issues of the city problems in the city. transportations and .vehicular traffic noise problems are contributed by various types of v or automobiles. during this study, six major al wasti, al askary, al nasir and north garage) measurements were captured at points or week [ sunday 3rd , monday 4th , and tuesday 5 pollution and super passing on many occasions to the prescribed levels by maximum level noise pollution value was 94.6 db university , while minimum level noise pollution value was 48 db zoning was prepared for kirkuk city for top peak working three days. the and could be used as a considerable point another hand, the map reflected indirectly the means a zone of a high air pollutions levels keywords: arcgis, air pollution, kirkuk, 1. introduction sound is a physical phenomenon that stimulates the sense of hearing (purohit 2010). noise is unwanted sound without agreeable musical quality. the differences between those two terms sound and noise only when the effects of a undesirable. american encyclopedia based on khwarizmi engineering journal,vol. 13, no. 4, p.p. 137151 (2017) land zoning in the base of traffic noise pollution leve arcgis: kirkuk city as a case study mustafa ali * ako rashed hama ** younis mustafa ali *** college of engineering/ university of kirkuk, civil engineering/ komar university of science and technology faculty of engineering/ university of sulaimania *email: shnoma@yahoo.com **email: ako.rashed@komar.edu.iq ***email: younis.ali@univsul.edu.iq (received 24 november 2016; accepted 20 june 2017) https://doi.org/10.22153/kej.2017.06.002 an approach to assign the land area of kirkuk city [ a city located in 83 kilometers south of erbil [ climatic atlas of iraq, 1941 and arc map10.3, zones of different traffic noise pollution help and of it’s of a high interest point for the future of the city. also, it may be considered as a reference in and sounds of horn of vehicles are the major sources of traffic noise pollutions .vehicular traffic noise problems are contributed by various types of vehicles such as heavy and major regions within the city were selected (governorate region, baghdad north garage). a survey for all those six regions were taken measurements were captured at points or near to the intersections for a duration of three different periods days per a , and tuesday 5th] of january 2016. the results show super passing on many occasions to the prescribed levels by central pollution level noise pollution value was 94.6 db(a) in alwasti region near to the road that level noise pollution value was 48 db(a) in alnasir region. as a result, a noise map zoning was prepared for kirkuk city for top peak working three days. the prepared noise distribution map a considerable point for the future during designing projects related to indirectly the amount of regional air pollutions. high distributed levels specially cox and nox gaseous pollutions. kirkuk, land zoning, noise pollution, traffic noise. is a physical phenomenon that stimulates the sense of hearing (purohit et al., wanted sound without the differences two terms sound and noise are a sound are encyclopedia based on psychological factors states that the extremely unpleasant to ears ( 2007).traffic noise is one of most immediate and identifiable environmental problem associated with rapid degree urbanization, and population noise is considered to be important sources of noise pollution which have adverse effects al-khwarizmi engineering journal (2017) traffic noise pollution levels case study ako rashed hama ** technology the northern of iraq, 236 iraq, 1941-1970 ] into different ferent traffic noise pollutions. land zonings process the future of kirkuk city especially reference in solving the traffic jam are the major sources of traffic noise pollutions and medium trucks or buses overnorate region, baghdad road, were taken place and noise different periods days per a of january 2016. the results showed a high level of noise ollution control board (cpcb) , the road that leading to kirkuk nasir region. as a result, a noise map prepared noise distribution map will help related to transportations. also in igh distributed noise pollution zones states that the noise is extremely unpleasant to ears (khitoliya, 2007).traffic noise is one of most immediate entifiable environmental problem degree industrialization, and population growth traffic noise is considered to be one of the most important sources of noise pollution which on human health shno mustafa ali al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 137151 (2017) 138 (williams and mccare, 1995). the main sources of vehicle noise pollution come from engines, exhaust systems, tires interacting with the road, horns, aerodynamic friction by the interaction between vehicles, sound of cooling fans, gearboxes and brakes. the most serious health hazards associated with high levels of noise exposure is deafness which initially causes temporary hearing problem or deafness while prolonged exposure to high levels of noise pollution causes a permanent deafness hearing damage (singh and kaur,2007). some of the adverse effects of the noise pollution are the interfering with speech. also, noise leads to emotional and behavioral stresses such as increasing of the heart failure, headache and blood pressure. besides that, noise effect on the patients who need rest and silence (balashanmugam et. al., 2013). traffic noise will continue to be increased in magnitude and severity due to population growth, urbanization and the associated growth in the use of automobiles. it will also continue to be growing due to the sustainable growth of vehicles (types and models). highway noise pollution can be defined as the sum of the total noise produced in a specified point due to all the moving vehicles using that highway, thus produced noise pollution from vehicles depends on the type of the vehicle and its mode of operation (balashanmugam et. al., 2013). the social surveys are showing that a dissatisfaction towards the traffic noise will express by people in their houses sometimes depends on the variability of the noise. automobiles constitute the largest group of noisemakers. in main cities, about (60 -70) % of the noise pollution comes from the traffic roads (khitoliya, 2007). (singh and kaur, 2007) reported that noise pollution levels reached 70 – 75.4 db in the day times in the cities. the results of (krishna et al., 2007) indicated a high noise pollution levels in the main roads in nepal which were 60.1 db to 110.2db, and the noise was produced mainly from different motor vehicles ranged from 91.2 db to 121db. study of (jamrah et al. 2006) in amman shows as high noise levels in day times as 46 – 81 db(a) compared to night times which were 58 – 71 db(a). 2. materials and methodology for the purposes of measuring traffic noise pollution for the selected regions , six different site locations have been selected in kirkuk city as in the (table 1). the data have been taken during heavy traffic flowing conditions three different periods of time per a day so that they may represent and cover the noise pollution of the city. the time periods were as: 8:00 a.m. to -9:00 a.m. (supposed to be peak traffic hour density of the day) , 12:00 a.m. to 1:00 p.m. (supposed to be the end of the governmental staff working hour) and 5:00 p.m. to 6:00 p.m. (time of the evening people marketing). the process is carried out continuously for three days of 3rd, 4th and 5th of january 2016. the locations of the understudy area of the six sites shown in all the figures. noise level survey was carried out to assess the noise distribution environment in the city. the noise levels were assessed by using sound level meter device (dt-85a). this instrument measures the sound pressure level in db(a) (a-weighted decibel). since human ear does not respond uniformly to the sound of all deferent frequencies specially those which are in low and high levels of frequencies than that those which are at the median or speech frequencies,then in an attempt to duplicate the response of human ear, the sound level are often fitted with three internationally defined frequencies weighting filters a,b, and c. the a-weighted decibel db(a) is an adequate objective measurement providing a reasonable correlation with objectively determined ranking (khitolya,2007) . sounds of frequencies from 800 to 3000 hz are covered by the a weighted scale. if the sound pressure level, l1 in db is measured at r1 meters, then the sound pressure level, l2 in db at r2 meters is given by, l2 = l1 20 log10 (r2/r1) …(1) shno mustafa ali al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 137151 (2017) 139 if the sound levels are measured in terms of pressure, then, sound pressure level, lp is given by, lp = 20 log10 (p/po) db(a) ...(2) p is effective sound pressure in n/m2 p° is reference pressure usually 2*10-5 n/m2 (purohit et al., 2010). the lp is measured against a standard reference pressure, po is equivalent to zero decibels. the sound pressure is the pressure exerted at a point due to a sound producing sourc . the day night equivalent noise levels of a community (ldn) can be expressed as: ldn = 10 x log10 [15/24 (10(ld/10)) + 9/24 (10[ln + 10)/10]] …(3) where, ld = day-equivalent noise levels (from 6am 9 pm), db (a) ln = night equivalent noise levels (from 9 pm 6 am), db (a) the day hours in respect to assessment of noise levels, is fixed from 6 am 9 pm (i.e., 15 hrs) and night hours from 9 pm 6 am (i.e., 9 hrs). a sound level of 10 db is added to ln due to the low ambient sound levels during night for assessing the ldn values. definition of sound pressure table 1, description of the studied locations in kirkuk city sites location north east description 1 governorate region 35°27'35.47"n 44°22'53.90"e which have heavy traffic volume because it is the center of kirkuk and considers as a commercial area. 2 baghdad street 35°25'29.52"n 44°22'22.84"e near traffic intersection which considers main road 3 al waseti region 35°25'17.25"n 44°20'38.14"e this is near the university of kirkuk and has heavy traffic volume. 4 al askary region 35°24'43.93"n 44°24'15.01"e residential area. 5 al-nasir region 35°25'17.94"n 44°24'15.98"e residential area, which is near a bridge with heavy traffic volume. 6 garage shemal region 35°28'20.37"n 44°24'16.49"e table 2, details of the selected study sites in kirkuk city geometrical description width of median strip (m) width of road (m) location sites have six paths only three paths were open for vehicles movements 4.95 11.5 intersection of kirkuk governorate 1 have six paths all paths are opening for vehicles movements 4.0 11.5 baghdad street 2 have eight paths were open for vehicles movements 1.5 7.0 al-nasir street intersection 3 have six paths open for vehicles movements 2.5 9.5 north garage 4 have six paths open for vehicles movements 2.0 10 al waseti intersection 5 have eight paths only four paths were open for vehicles movements 2.0 10 al askary intersection 6 shno mustafa ali al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 137151 (2017) 140 measurements of traffic noise were done by sound level meter type dt-85 a which is a small meter measures the noise for 15 minutes in each site then the screen of meter show maximum and a minimum value of noise by unit db(a). also the locations of the points were recorded using gps device. arcgis 10.3 software was used for zoning kirkuk land area based on the recorded noise levels. the values of noise pollution level were mapped as data points relative to their specific locations. to cover the entire area, a contouring method was used based on idw (inverse distance weighted) spatial interpolation technique. generally, interpolation predicts cell values in a raster format using a given through a limited number of sample data. it is a veritable tool for prediction of unknown values for a given geographic point data which in this study is noise pollution sound levels (yilmaz et al. 2005, banerjee et al. 2009). idw however explicitly implements the law of geography, which is pivoted on the hypothesis that closer things are more related than those farther apart. for its prediction, idw utilizes the given values surrounding the predicted location. it predicts that each given point has a local influence that shrinks with space; thereby giving greater weights to points closest to the prediction location, based on distance decay effect. this process leads to the procedure being referred to as inverse distance weighted. this technique was applied to measure the spatial distribution and range of noise pollutions for kirkuk city for the selected six sites in the area and for the consequent three days and each for six deferent periods of a day. 3. results and discussions the data of traffic noise pollution showing a high values of the noise level in regions that has been chosen in kirkuk city and not satisfactory as per standards prescribed by central pollution control board (cpcb) in the table (3): table 3, ambient air quality standards in respect of noise by (cpcb) (khitolya, 2007) night time db(a) daytime db(a) area 70 75 industrial area 50 65 commercial area 45 55 residential area 40 50 silence zone in the first region as the results of measuring the sound pressure levels shown in the table (4), the values of maximum and minimum ranged from values 50.4 to 88.8 db(a). governorate region considered to be as a commercial area and by referring to table 2, the maximum permissible values of sound pressure level is 65 db (a) in all time of the measurement due to vehicles movability and because this site is center of kirkuk city and contains many markets, restaurants, and supermarkets that lead values of noise level higher than the standards as listed in table 2. table 4, noise levels in db(a) at governorate site tuesday 5th jan. 2016 monday 4th jan. 2016 sunday 3rd jan. 2016 time min. max. min. max. min. max. 50.4 77.5 69.6 85.2 52.8 77.4 08:008:30 67 83.6 71.6 87.7 65.6 81.2 08:30-9:00 62.8 76.2 74 88.8 51.9 75.6 12:00-12:30 57.7 71.2 70.8 86.5 51.6 78.3 12:30-01:00 52.6 79.4 71.2 84.2 65.4 80.6 05:00-05:30 64.7 72.8 79.3 80.2 65.0 82.3 05:30-06:00 table (5) presents the values of noise level pollutions measurements in baghdad street region which considered as the main road in kirkuk city, maximum value of noise was 91 db(a) in the third day of the noise measurement which was very high comparing to the limits that prescribed in table (6) for main road which limit as 70-80 db, while minimum value was 60.4 db(a) on the first day. table 5, noise measurements pollutions levels in db(a) at baghdad street. table 6, noise levels of different sources of traffic (khitolya, 2007) noise level db(a) source of noise 90-110 rail traffic 80-90 heavy road traffic (highway) 70-80 medium road traffic (main road) 60-70 light road traffic (side street) table 7 represents the values of noise in the third region at alwasti .the location of the site is near university of kirkuk which have heavy traffic volume during all day hours. the values were high during 8:00-8:30 a.m. because the students starting attendance to their collages , also after 12 p.m. when students came back to their homes and this make noise level very high in this site , maximum value of noise was 94.6 db(a)as shown in the table(5) which considerably was of higher pollution measurements values comparing to the rest five selected sites. table 7, noise levels at al wasti region. tuesday 5th jan. 2016 monday 4th jan. 2016 sunday 3rd jan. 2016 time min. max. min. max. min. max. 69.5 85.9 74.1 90.3 71 88.2 08:008:30 69.1 87.7 69.4 87.8 73.7 91.2 08:30-9:00 71.6 84.7 71.9 92.7 67.7 93.3 12:00-12:30 70.8 88.8 72.5 92 58 94.6 12:30-01:00 60.9 86.5 70.5 92.1 70.4 87.2 05:00-05:30 62.2 84.9 72.4 87.5 74.8 89.5 05:30-06:00 noise levels of al askary region listed in table (8) which is residential, range of noise is (48.4 83.2) db(a) the values are higher than the prescribed limits in table 2 which is 55 db and this belongs to the noise pollution levels that came from many shops of woodworkers and markets of food materials and greengrocers found on this site. table 8, noise pollution levels at al askary region. tuesday 5th jan. 2016 monday 4th jan. 2016 sunday 3rd jan. 2016 time min. max. min. max. min. max. 64.2 81.5 56.6 77.5 51.0 78.9 08:008:30 66.8 75.0 52.6 84.1 48.9 81.9 08:30-9:00 64.8 80.1 61.7 80.8 63.2 76.5 12:00-12:30 59.9 76.5 49.8 73.7 48.4 69.0 12:30-01:00 69.0 83.2 49.0 63.7 61.7 82.9 05:00-05:30 64.8 80.8 65.7 80.0 59.8 68.5 05:30-06:00 in the fifth region as its shown in table (9) values of noise pollutions in alnasir region were higher than the standards as table 2 ,because this region considered as a residential area and near a bridge with heavy traffic volume and have many exhibitions of ceramic and construction materials make the levels of noise pollution of higher levels and the maximum value was 81.5 db(a), while the minimum value was 48 db(a). tuesday 5th jan. 2016 monday 4th jan. 2016 sunday 3rd jan. 2016 time min. max. min. max. min. max. 74.7 84 66.2 78.5 70 77.9 08:008:30 69.9 75.9 62.3 77.5 61.2 72.4 08:30-9:00 81.3 90.3 69.2 82.4 63.4 75.6 12:00-12:30 79.6 88.5 70.0 77.0 64.9 78.6 12:30-01:00 73.0 91.0 74.3 82.4 60.4 72.4 05:00-05:30 66.2 87.2 69.2 77 63.9 68.9 05:30-06:00 shno mustafa ali al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 137151 (2017) 142 table 9, noise levels at al nasir region. tuesday 5th jan. 2016 monday 4th jan. 2016 sunday 3rd jan. 2016 time min. max. min. max. min. max. 62.1 81.5 53.2 77.4 62.2 71.8 08:008:30 59.6 75 52.5 74.4 65 69 08:30-9:00 60 73.8 51.6 79.9 48 80.7 12:00-12:30 64.8 80.1 56.2 71.1 68.8 73 12:30-01:00 66.2 76.5 56 78 58.9 66.6 05:00-05:30 59.4 70.1 59.6 76.5 53.8 74.5 05:30-06:00 last site was north garage which considers as an industrial area and has heavy hourly traffic volume from kirkuk to the governorates of the north of iraq. the maximum pollution levels values were 93.2 db(a) as shown below in table (10) which is higher than limited values in table2. the reason behind the high levels of noise pollutions refers to that this site contains many shops of maintenance workshops and operation and maintenance of cars also repairing parts of those vehicles flashed and made accidents. . table 10, noise levels at north garage. third day second day first day time min. max. min. max. min. max. 74.3 75.4 68.2 80.1 76.2 83 08:008:30 66.3 88.9 52.3 83.2 67.9 88.4 08:30-9:00 77 90 55.1 78.9 64.3 75.6 12:00-12:30 80.5 92.3 60.4 88.3 68.4 79.3 12:30-01:00 72 86.2 58.2 80 73.8 85.8 05:00-05:30 74.5 87.4 56.1 75.1 80.1 93.2 05:30-06:00 fig. 1. hourly noise distribution for the peak morning and evening traffic flow 3 jan. 2015 kirkuk city. shno mustafa ali al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 137151 (2017) 143 fig. 2. daily noise distribution for the peak morning and evening traffic flow 3 jan. 2015 kirkuk city. shno mustafa ali al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 137151 (2017) 144 fig. 3. hourly noise distribution for the peak morning and evening traffic flow 4 jan. 2015 kirkuk city. shno mustafa ali al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 137151 (2017) 145 fig. 4. daily noise distribution for the peak morning and evening traffic flow 4 jan. 2015 kirkuk city. shno mustafa ali al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 137151 (2017) 146 fig. 5. hourly noise distribution for the peak morning and evening traffic flow 5 jan. 2015 kirkuk city. fig. 6. daily noise distribution for the peak morning and evening traffic flow 5 jan. 2015 kirkuk city. shno mustafa ali fig. 7. max, min and average hourly noise distribution for the traffic flow 3 jan. 2015 kirkuk city. fig. 8. max, min and average hourly noise fig. 9. max , min and average hourly noise distribution for the traffic flow 3 jan. 2015 kirkuk city. al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 147 max, min and average hourly noise distribution for the traffic flow 3 jan. 2015 kirkuk city. max, min and average hourly noise distribution for the traffic flow 3 jan. 2015 kirkuk city. max , min and average hourly noise distribution for the traffic flow 3 jan. 2015 kirkuk city. khwarizmi engineering journal, vol. 13, no. 4, p.p. 137151 (2017) max, min and average hourly noise distribution for the traffic flow 3 jan. 2015 kirkuk city. distribution for the traffic flow 3 jan. 2015 kirkuk city. max , min and average hourly noise distribution for the traffic flow 3 jan. 2015 kirkuk city. shno mustafa ali fig. 10. max , min and average hourly noise distribution for the traffic flow 4 jan. 2015 kirkuk city. fig. 11. max , min and average hourly noise distribution for the traffic flow 4 jan. 2015 kirkuk city. fig. 12. max , min and average hourly noise distribution for the traffic flow 4 jan. 2015 kirkuk city. al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 148 min and average hourly noise distribution for the traffic flow 4 jan. 2015 kirkuk city. max , min and average hourly noise distribution for the traffic flow 4 jan. 2015 kirkuk city. min and average hourly noise distribution for the traffic flow 4 jan. 2015 kirkuk city. khwarizmi engineering journal, vol. 13, no. 4, p.p. 137151 (2017) min and average hourly noise distribution for the traffic flow 4 jan. 2015 kirkuk city. max , min and average hourly noise distribution for the traffic flow 4 jan. 2015 kirkuk city. min and average hourly noise distribution for the traffic flow 4 jan. 2015 kirkuk city. shno mustafa ali fig .13. max, min and average hourly noise distribution for the traffic flow 5 jan. 2015 kirkuk city. fig. 14. max, min and average hourly noise fig. 15. max, min and average hourly al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 149 max, min and average hourly noise distribution for the traffic flow 5 jan. 2015 kirkuk city. max, min and average hourly noise distribution for the traffic flow 5 jan. 2015 kirkuk city. max, min and average hourly noise distribution for the traffic flow 5 jan. 2015 khwarizmi engineering journal, vol. 13, no. 4, p.p. 137151 (2017) max, min and average hourly noise distribution for the traffic flow 5 jan. 2015 kirkuk city. distribution for the traffic flow 5 jan. 2015 kirkuk city. r the traffic flow 5 jan. 2015 kirkuk city. 4. conclusion this study was to evaluate the traffic noise pollution in kirkuk city. high levels of traffic noise pollution due to vehicles, heavy trucks, governmental clerks pathways to their offices and others were observed in this study. the recorded levels of noise pollutions were over the standards. this study shows high levels of noise pollutions in the zones where the university is located and also where the governorate buildings council region is located as well. results showing that alwasti and baghdad road regions were classified as noisy zones due to the high traffic flow of heavy trucks mobility and trailers that inter the center of kirkuk from the southern cities and that area represent the entrance of the city. those zones are also are noise pollution zones due to the nature of the wide roads passes through and they have. while for those regions where the governorate buildings are located, lower levels of noise pollution recorded and except just during the peak working hours of the day. as a recommendation, and to reduce the noticed traffic noise pollutions in the zones, several steps may be implementing. proper maintenance for the cross roads and solving the flexibility of the jammed traffics flow will help to decrease that high levels of noise pollutions. quiet zones where the hospitals and the educational institutions located should be kept as silent zones as well as residential area. planting of green trees along roads and high noise pollution areas will be helpful to absorb a fraction of the high sound pressure levels because they will act as barriers. the high sound level pollution regions indirectly showing the areas of high air pollution regions that need immediate actions to reduce that air pollutions and advices. 5. references [1] banerjee, d., s. k. chakraborty, s. bhattacharyya, and a. gangopadhyay. "appraisal and mapping the spatial-temporal distribution of urban road traffic noise." international journal of environmental science & technology 6.2 (2009): 325-35. print. [2] khitoliya, r. k. enviroment pollution: management and control for sustainable development. new delhi: s chand, 2014. print. [3] li, bengang, shu tao, r.w. dawson, jun cao, and kinche lam. "a gis based road traffic noise prediction model." applied acoustics 63.6 (2002): 679-91. print. [4] murthy, v. krishna, ahmad kamruzzaman majumder, sanjay nath khanal, and deepak prasad subedi. "assessment of traffic noise pollution in banepa, a semi urban town of nepal." kathmandu university journal of science, engineering and technology 3.2 (2010). print. [5] p.balashanmugam, v.nehrukumar, k.balasubramaniyan, and g.balasubramanian. "effect of road traffic noise pollution in cuddalore town: a case study." international journal of innovative research in science, engineering and technology. research and reviews, 21 apr. 2015. web. 11 mar. 2017. [6] shammi, q. j. text book of environmental sciences. jodhpur, 2007. print. [7] williams, i.d., and i.s. mccrae. "road traffic nuisance in residential and commercial areas." science of the total environment 169.1-3 (1995): 75-82. print. [8] yilmaz, guzel, and yuksel hocanli. "mapping of noise by using gis in şanliurfa." environmental monitoring and assessment 121.1-3 (2006): 103-08. print. �� ا� ارز�� � ��� �و ��ط�� � )2017( 137-151، ���� 4، ا���د�13ا������� ا�� �������* )!ت ا�*� ث ا�,!+� �*(!)�� �' $�&ا�% ��!$!ت و ��!ط� ا���ندرا�� �ام 203!�1 ا��0وري*�!3 arcgis :ك را�� ��)�� 606��ذج ا �2 *** ) 2= �:�9% ��� **+!6 ر;�� $�> * ;� �:%�9 ��� ���ك/ ���� ا������*� ���� ��ر �����م وا�'&���� �/ %$# ا������ ا�"�!�� **�� ���� � �� ا�$��"�!��/ ا���������� ***�� shnoma@yahoo.com :+!و� * ا�.�-� ا,�&' ako.rashed@komar.edu.iq : ا�.�-� ا,�&'�و!+ ** younis.ali@univsul.edu.iq :ا�.�-� ا,�&'�و!+*** ��> ا� �.'��اق -"&9 ان ت$'7�د ���� ھ4ه ا��را�� و���� �2"���1'�ى ت����ك وا�'+ ت<= >"�ل ا�� ��-���# ��ب ارe�c �٨٣# >"�ل �bcاد و �٢٣٦'<$�# ���طi و �$�h�ت kت ا��ة ا�"$'�-�< m�h 9� �7�'n� +o��'وري ا���v ت"u ا�'�nام .��t� ا�r�s�q+ ا�"�!�c و ��q�st ر�w arcgis xذ� e 9 ا� .��� kت ا��h�$"دة ان ت<$�# ا���'� ��oت ت���-�'$��m�h 9 ا�'��ث ا�r�s�q+ ا�"�وريو �'.�-�� طi ذات e.>'$"� ة�و ����ك ��-����� 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+t+ ا��]� db(a) ٤٨و��!u ا��!�� �hھ� % +q�r�sت ا�'��ث ا��-�'$��اq[ . ��"�-�� ا�"�وري �'�ز-= nذي ا�'�ھ4ه ا� i^!�"�� ]qا�\ �s-9 ان ت&�ن ا&"-+qزات و �ث ا���ا�bا� m�h 9� . nox , soxا�"��o�ت ا�b�ز-�ا,!.��o�ت ����w�ص و ا�x!o و و \]�w� t+ ا�"�^<� ا,!.��o�ت ا�b�ز-� 70-78امل صالح al-khwarizmi engineering journal,vol. 13, no. 1, p.p. iraqi bauxite and porcalinite rocks and technical college email: (received 29 https://doi.org/10.22153/kej.2017.01.004 abstract locally natural occurring iraqi rocks of bauxite and porcelanite with the addition of different proportions of mgo and al additives on the physical and thermal properties of the prepared refractories were investigated. many batches of bauxite/mgo, bauxite/al2o3 mixture is milled and classified into different size fractions; fine (less than 45μm) 40%, middle (45 coarse (75-106μm) 20% . x-ray diffraction technique was used to identify formed by semi dry pressing with the addition of few drops of water as a binder. for 2hrs. physical properties (linear shrinkage, density and porosity), diffusivity and specific heat) were measured for all the prepared samples the results show the increasing of density is susceptible to the thermal properties, and also mgo to the natural rocks have a limited effect, and the values of the parameters above for the natural rocks, were in the levels to be used as a refractory material for lining a metal fusion furnaces and other applications. keywords: bauxite, refractory brick, porcelanite stone, physical properties, thermal properties 1. introduction a refractory is a material that retains its shape and chemical identity during exhibition to temperatures and used in such applications that require extreme resistance to heat. almost all raw materials used by refractory manufacturers occur naturally. but they are prepared or processed in several ways to lower the fluxes, unwanted oxides as much as possible. in general, refrac materials may contain the following silicon dioxide, aluminum oxide, mag oxide, calcium oxide, chromium oxide zirconium dioxide [1]. firebricks, like any other ceramic products are prepared through three main stages: raw materials preparation (mixing according to definite proportion using milling process and then sieving khwarizmi engineering journal,vol. 13, no. 1, p.p. 7078 (2017) iraqi bauxite and porcalinite rocks based refractory, preparation and studying properties amel s. merzah technical college –baghdad /middle technical university email: amelmerzah@gmail.com may 2016; accepted 15 january 2017) https://doi.org/10.22153/kej.2017.01.004 rocks of bauxite and porcelanite (after pre calcinations at 1000oc for 1hr proportions of mgo and al2o3, to prepare refractory materials. the effects of these additives on the physical and thermal properties of the prepared refractories were investigated. 3, bauxite/mgo/al2o3, and porcelanite/ mgo/al2o3 were prepared. mixture is milled and classified into different size fractions; fine (less than 45μm) 40%, middle (45ray diffraction technique was used to identify the structure of bauxite and porcelanite rocks. the samples were with the addition of few drops of water as a binder. these samples were sintered at 1100 shrinkage, density and porosity), and the thermal properties (thermal conductivity, diffusivity and specific heat) were measured for all the prepared samples. the increasing of density is susceptible to the thermal properties, and also the addition of al mgo to the natural rocks have a limited effect, and the values of the parameters above for the natural rocks, were in the levels to be used as a refractory material for lining a metal fusion furnaces and other applications. brick, porcelanite stone, physical properties, thermal properties. a refractory is a material that retains its shape during exhibition to high applications that require extreme resistance to heat. almost all raw materials used by refractory manufacturers occur naturally. but they are prepared or processed in several ways to lower the fluxes, unwanted oxides as much as possible. in general, refractory oxides: magnesium chromium oxide, and other ceramic products are through three main stages: raw materials (mixing according to definite milling process and then sieving to a definite particle size), pressing and densification through the sintering the main constituents of firebricks contain alumina (al2o3) and silica (sio systems are actually based on kaolinitic clays, which generally produce a substantial shrinkage when sintered [3]. fireclay refractories, also known as chamotte bricks, belong to the aluminosilicate group with alumina content between 25-45 wt%. the foreboding raw material for making fireclay refractories was kaolin. kaolin mainly composed of alumina, which is used in the manufacturing of fireclay refractories among other industrial minerals [4]. the higher the alumina contents of kaolin, the higher the refractoriness. raw materials are thus classified to be of high al-khwarizmi engineering journal , preparation for 1hr) were used, . the effects of these were prepared. the -75μm) 40%, and the samples were these samples were sintered at 1100oc and the thermal properties (thermal conductivity, the addition of al2o3 and mgo to the natural rocks have a limited effect, and the values of the parameters above for the natural rocks, were in the pressing to compacts sintering process. main constituents of firebricks usually ) and silica (sio2). these based on kaolinitic clays, substantial shrinkage fireclay refractories, also known as chamotte bricks, belong to the aluminosilicate group with 45 wt%. the raw material for making fireclay was kaolin. kaolin mainly composed he manufacturing of fireclay refractories among other industrial minerals [4]. the higher the alumina contents of kaolin, the higher the refractoriness. raw materials are thus classified to be of high pdf created with pdffactory trial version www.pdffactory.com https://doi.org/10.22153/kej.2017.01.004 mailto:amelmerzah@gmail.com https://doi.org/10.22153/kej.2017.01.004 http://www.pdffactory.com http://www.pdffactory.com amel s. merzah al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 7078 (2017) 71 refractory value as the amount of alumina in them increases [5]. firebrick or refractory was the major consumables to industries wherever heat is used , and abrasion and acid resistance is required including the following industries: iron and steel, copper, gold, platinum, ferro-alloys, aluminum, cement, lime, glass, ceramics, foundries, and gas plants, chemical plants, petroleum plants, and power stations [6]. the iron and steel industry, considered as the largest consumer, estimated between 50-80% of the refractories produced worldwide. refractories used for the following purposes [7]. lining of plants for thermal processes, such as melting, firing, heat treatment furnaces, and transport vessels. fireclay refractory was charecterized by low thermal expansion coefficient, low thermal conductivity, low specific gravity, low specific heat, low strength at high temperature, and less slag penetration [8]. in the present work naturally, locally occurring rocks, bauxite and porcelanites were used to prepare a refractory batch to be used in the above applications. bauxite is a rock formed from a laterite soil that severely leached from silica alumina and other soluble materials. bauxite, known as a soft white to gray to reddish brown rock with a pisolitic structure, earthy luster and a low specific gravity (sg: 2.02.5) [15]. bauxite is a naturally occurring (in alanbar and western desert in iraq), heterogeneous material composed primarily of one or more aluminum hydroxide minerals, plus various mixtures of silica, iron oxide, titania, aluminosilicate, and other impurities in minor or trace amounts[12]. porcelanites are siliceous rocks, found in iraq, are from an industrial bed of (0.5 to 1.3 m) thickness in the safra, and trafawi site of the jeed formation in al-rutba region, western of iraq, it composed of opalct (crystallite– tridymite crystal stratification) and are derived from biogenic amorphous opalline silica, associated with shale. pocelanites; these are siliceous rocks, they are part the phosphorene in the western (digme and akashat formations respectively)[13]. the present work aims to study the physical and thermal properties of refractory prepared from bauxite/alumina/magnesia and porcelanite/ alumina/ magnesia, and decide the effect of addition, and their effect on the physical and thermal properties of refractory. 2. experimental part local raw materials, bauxite with chemical analysis shown in table (1), porcelanite rocks with a mineral analysis ( from state company of geological survey and mining, baghdad, iraq), shown in table (2), alumina and magnesia were used as starting materials. the natural rocks were pre calcined at 1000oc for 1hr. the same technology was used to prepare a refractory sample with varying proportions as given in table (3) and table (4). table 1, anbar and western desert bauxite chemical composition. table 2, mineral analysis of as received porcelainte stone. table 3, mixing ratios in weight percentages of starting materials to prepare bauxite based refractory. the mixture is milled and classified into different size fractions; fine (less than 45μm) 40%, middle (45-75μm) 40%, and coarse (75106μm) 20% . al2o3 sio2 fe2o3 tio2 cao mgo compound 60 20 1.3 1.8 1.2 1.1 maximum wt% magnesia wt% alumina wt% bauxite wt% batch number 40 60 1 40 60 2 20 20 60 3 100 4 wt.% `compound 64.28 opalct 10.42 quartz 7.72 clay 7.12 dolomite 6.30 calcite 1.83 apatite 0.63 halite 0.61 gypsum pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com amel s. merzah al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 7078 (2017) 72 table 4, mixing ratios in weight percentages of starting materials to prepare porcelanite based refractory. the mixing process was achieved using a porcelain ball mill as shown in figure (1); sieve analyzer was used to classify the powder particle sizes as shown in figure (2). the formed samples were sintered in an electrical furnace at 1100°c for 2 hrs. x-ray diffraction technique was used to identify the local rocks composition and contents. physical and thermal properties were measured for all samples, such as density, porosity, shrinkage, thermal conductivity, thermal diffusivity and specific heat. the thermal properties such as thermal conductivity, thermal diffusivity, and specific heat, were measured for each sample by "hot disc" system in the material engineering department in the university of technology as shown in fig (3,a and b). the results were supplied from computer linked with the device. fig. 1. a porcelain ball mill used for milling and mixing. fig. 2. sieve analysis system. (a) (b) fig. 3. (a)thermal properties apparatus, (b) holder of the sample. physical property requirements for shaped and unshaped refractories are different. for shaped refractories, the main requirements are their density and porosity and dimensional tolerance, which achieved in the present work. magnesia wt% alumina wt% porcelanite wt% batch number 100 1 20 20 60 2 40 10 50 3 10 40 50 4 25 25 50 5 25 50 25 6 50 25 25 7 20 40 40 8 pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com amel s. merzah al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 7078 (2017) 73 apparent density: the apparent density is generally considered in conjunction with apparent porosity. �a= �������× �w …(1) where: �a: is the apparent density for the prepared samples in gm/ cm3 wd: weight of dried sample (gm) wi: weight of immersed sample (gm) ws: weight of wet ( open pors filled with water sample (gm) �w: density of water in gm/ cm3 shrinkage: shrinkage means that mixture could absorb much water, which in turn indicates fine mixture particles. linear shrinkage = ������� × ���% …(2) where: h 1: height of the sample before sintering in cm h2: height of the sample after sintering in cm. apparent porosity: -porosity is a measure of the effective open pore space in the refractory and is expressed as the average percentage of open pore space in the overall refractory volume. porosity % = ���������� × ���% …(3) where: wd: weight of dried sample (gm) wi: weight of immersed sample (gm) ws: weight of wet ( open pors filled with water sample (gm) 3. results and discussion the chemical composition of bauxite as received was given in table (1), from which it is appeared that the main compounds are alumina and silica with small weight ratios of other oxides. the x-ray data for iraqi bauxite used in the present work was shown in figure (4). kaolinite 2 .bohmite 3 .gibbsite 4 .anatase 5 .quartz 6 .calcite 1. fig .4. x-ray diffraction pattern for iraqi bauxite as reserved from the geologized surveying company. the figure shows that the bauxite rock consist of kaolinite, anatase, bohmite quartz, gibbsite, and calcite. after cacination the alumina and silica form the mullite. table (2) shows the chemical analysis of the porcelanite stone as received from the source, the silica minerals which are mainly disordered α cristobalite opal-ct and quartz are the main compounds. chemical analysis of opal-ct shows that they contain an appreciable amount of alkaline and alkaline earth elements (millot, 1970)[9], which means that if foreign cations are available in appreciable amount, opal-ct can precipitate. the experimental results by kastner et al. (1977)[10] suggest that magnesium hydroxides are the most important components responsible for the increased rate of amorphous silica (opala) digenesis. this is analogous to aragonite, an unstable form of calcite, which precipitates in the presence of magnesium ions (health and moberly, 1971) [11]. in carbonates of over 80 per cent cac03, as in figure 4, both the scarcity of aluminum and metallic cations favor precipitation of opal-ct only , the porcelanite after calcinations at 1000oc for 1hr, x-ray diffraction data was given in figure (5). pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com amel s. merzah al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 7078 (2017) 74 fig. 5. x-ray diffraction data of porcelanite mineral, (examination was conducted in laboratories of sheffield hallam university using a theta to theta diffractometer (philips)). it was appeared from figure (5) that there are three strong peaks which indicates appearance of silica, at angle 2 theta (21.6909 and 20.7108) silica appeared in (tridymite form), and at (30.9435) silica appears in quartz form and final small peak for (caco3).the later compounds appeared because of the calcinations at 1000oc, the contents of the rock which is seen in table (2), are reacted with each other to form the compounds appeared in fig.(5). table (3) shows the mixing ratios in weight percentages of starting materials to prepare bauxite based refractory, using the largest percentages of bauxite in order to get the glassy phase or liquid phase and increase the shrinkage and density after sintering the samples, these results were appeared from table (5), which shows the physical and thermal properties for the bauxite based prepared refractory, the denser compound is the alumina as seem in sample number 1 which has the greater density 2.16 gm/cm3, while sample number 3 has the lowest. reduction of porosity in the sample number 4 which is mainly bauxite is due to the presence of impurities have low melting points, increases the glassy phase in the prepared refractory. increasing mgo give rise to a reduction in the viscosity of the liquid phase formed, so the pores filled and shrinkage increased to 8%. also the physical and thermal properties depend on the size graduation. table 5, the physical and thermal properties for the bauxite based prepared refractory. specific heat mj/m3.k diffusivity mm2/sec thermal cond w/m.k sintered density gm/cm3 % apparent porosity l.sh. sample no. 1.09*103 0.35 0.66 2.16 27.7 0.0270 1 2.09*103 0.34 1.55 1.77 21.2 0.0830 2 1.11*103 0.43 0.85 1.79 27.2 0.0350 3 0.91*103 0.24 0.38 1.73 9.6 0.0026 4 porosity can be controlled by controlling the size distribution of the particles. higher the porosity, lower will be the strength of the brick. bricks with lower porosity will have greater resistance to slag attack and more sensitiveness to fluctuations in temperature. their thermal conductivity will be more. it can be seen from table (5) that the apparent porosity is ranged between (9.6-27.7) %. the relationships between apparent porosity and the pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com amel s. merzah al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 7078 (2017) 75 percentages of alumina and magnesia percentage, the higher the alumina the higher the density, this is due to the strengthening by alumina, the high density is balanced with high porosity , while the sample of only bauxite shows the lower. chemical reactions may take place between the components, mgo,al2o3, fe2o3, and cao. low fusion temperature compounds were formed, which flow easily into the pores and increase the density of refractory. also the surface tension of liquid phase cause a compacting and reducing the dimensions of the refractory. the table (6) and figures (6, 7 and 8), shows the physical and thermal properties of the prepared porcelanite based refractory. table (6) the physical and thermal properties of the prepared porcalinite based refractories. specific heat mj/m3.k diffusivity mm2/sec thermal cond w/m.k apparent porosity % sintered density gm/cm3 l.sh. sample no. 2.27 0.19 0.42 10.6 1.36 0.031 1 2.06 0.21 0.34 11.2 1.44 0.025 2 1.26 0.29 0.36 10.1 1.44 0.030 3 1.93 0.14 0.27 10.8 1.39 0.030 4 1.90 0.16 0.31 11.1 1.42 0.024 5 1.24 0.21 0.25 10.9 1.40 0.029 6 1.95 0.17 0.33 10.5 1.40 0.051 7 1.36 0.21 0.28 11.8 1.51 0.017 8 fig. 6. the linear shrinkage, sintered density, thermal conductivity, and the diffusivity for different batches of the porcelanite prepared refractory (as given in table 4) fig. 7. the linear shrinkage, sintered density, thermal conductivity, and the diffusivity for the porcelanite prepared refractory as a function of al2o3 percentages. pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com amel s. merzah al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 7078 (2017) 76 fig. 8. the linear shrinkage, sintered density, thermal conductivity, and the diffusivity for the porcelanite prepared refractory as a function of mgo percentages. there is flocculating in the properties appeared in figures, in general all the prepared samples are suitable as refractory. high alumina ratio increase the density of the product. the impurities fluxes materials k2o,na2o, cao and mgo) that extent within the material structure reacts to form the large amount of fusible materials, which have small densities compared with the alumina and magnesia. 4. conclusions fireclay refractory's, like other ceramic products are processed through three main stages: raw materials preparation, consolidation to compacts and densification by sintering. the main constituents of fireclay refractory are alumina (al2o3) and silica (sio2). these systems are normally based on kaolinite clays which generally present substantial shrinkage when fired [12]. in the present work the bauxite and porcelanite rocks were used instead, because of their abundance in iraqi earth crust and it contains large percentages of kaolin and silica respectively. figures above shows the physical and thermal properties of the prepared refractory according to the formulas given in table (3,4), the stability in the values of these properties, especially the lowest values of shrinkage, suggest using the batches prepared as a good refractory material [13,14]. this is the first time porcelanite used as a main constituent for refractory applications, also the bauxite is expected to be good refractory material. the bauxite and the porcelanite are a suitable choice for refractories, because of the low costs and availability, suggested as a future material for fire bricks manufacturing. the effect of mgo and al2o3 addition have a limited effect on the thermal and physical properties of the bauxite and porcalinite, which ensure using the bauxite or porcalinite as a refractory material. 5. references [1] y. chen, m.m. abraham, m. t.robinson, j.b. mitchell and r.a. van konynenburg, proc. intern. conf. on radiation effects and tritium tech. fusion reactors, gatlinburg, tn. (1975), userda conf 750989 vol. ii. p. 492. [2] -chaouki sadik1, abderrahman albizane1, izeddine el amrani, "production of porous firebrick from mixtures of clay and recycled refractory waste with expanded perlite addition",j. mater. environ. sci. 4 (6) (2013) 981-986. [3] john baptist kirabira," characterisation of ugandan raw-minerals for firebricks -before and after sintering",royal institute of technology department of materials science and engineering division of mechanical metallurgy stockholm 2003. [4] d. salmon, s. baxendale, g. groboth, b. hay, u. hammerschmidt, r. brandt, s. sinnema, d. baillis, r. schreiner, j. blumm, e. dossou, ‘the certification of thermal conductivity and diffusivity properties of pyroceram 9606 as a reference material up to 1000 °c’, final report project htcrm, contract n° smt4-ct982211, 2003. [5] g. viruthagiri, sri nithya, nareshanada and n. shanumugan, "analysis of insulating fire bricks from mixtures of clays with sawdust addition", issn-2249-555x, vol.3, issue 6, june 2013. [6] john baptist kirabira," properties of ugandan minerals and fireclay refractories", doctoral thesis, stockholm, sweden 2005. [7] chesters, j.h. (1983). “refractories: production and properties”. institute of materials, london, uk. [8] fatai olufemi aramide, "production and characterization of porous insulating fired bricks from ifon clay with varied sawdust admixture", journal of minerals and materials pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com amel s. merzah al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 7078 (2017) 77 characterization and engineering, 2012, 11, 970-975. [9] millot, g., 1970. geology of clay: new york (springer-verlag). stein, c.l. and kirkpatrick, r.j., 1976. experimental porcelanate recrystallization kinetics: a nucleation and growth model, j. sediment. petrol, v. 46, p. 430-435. [10] kastner, m., keene, j.b., and gieskes, j.m., 1977. diagenesis of siliceous oozes-1. chemical controls on the rate of opal-ct transformationan experimental study, geochim. cosmochim. acta, v. 41, p. 10411059. [11] heath, g.r. and moberly, r., 1971. chert from the western pacific, leg 7, deep sea drilling project. in winterer, e.l., et [12] al-zubaidi, a.a.,(2010):origin of silica minerals in the geodes of the iraqi western deset. fifth international conference on the tethys. cairo university, cairo. [13] khaldoun s. al-bassam," geology of iraqi western desert ", iraqi bull. geol. min. special issue, 2007: p 145-168. [14] o.s. olokode*; p.o. aiyedun; d.m. raheem; f.t. owoeye and b.u. anyanwu, "production and characterization of clay – cow dung insulating fire – bricks", (issn: 2315-5124) vol. 1(7) pp. 162-167, october, 2012. [15] stephen stackhouse, lars stixrude and bijaya b. karki, "thermal conductivity of periclase (mgo) from first principles", prl 104, 208501 (2010) p h y s i c a l r e v i e w l e t t e r s, week ending 21 may 2010. [16] shigetaka wada, bongkoch piempermpoon, pao na nakorn, thanakorn wasanapiarnpong and supatra jinawath, "thermal conductivity of al2o3 ceramics: the inconsistency between measured value and calculated value" j. sci. res. chula. univ., vol. 30, no.1 (2005). pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com )2017( 70-78 صفحة ،2العدد ،13المجلد الھندسیة الخوارزمي جلةم صالح مرزة امل 78 الخصائص الفیزیائیة والحراریة لحراریات مصنعة من صخور البوكسایت والبورسلینات العراقیة امل صالح مرزة الجامعة التقنیة الوسطى /بغداد الكلیة التقنیة الھندسیة amelmerzah@gmail.com :البرید االلكتروني الخالصة تم ، درجة مئویة ولمدة ساعة واحدة١٠٠٠والمحروقة اولیآ بدرجة حرارة ) البوكسایت والبورسلینات(العراق في طبیعیاالصخور المحلیة الموجودة .نسب مختلفة من المغنیسیا وااللومینا وبإضافةاستخدامھا لتحضیر حراریات .فحص تأثیر ھذه االضافات على الخصائص الفیزیاویة والحراریة للحراریات المحضرةتم / مغنیسیا/ للبورسلینات أخرىالومینا وایضآ تم تحضیر وجبات / مغنیسیا/ البوكسایت، الومینا/ البوكسایت، مغنیسیا /تحضیر وجبات عدیدة من البوكسایت تم ،% ٤٠) ٧٥٤٥( والوسط ، % ٤٠)مایكرون ٤٥اقل من ( والكسور الحجمیة الى األحجامحسب بالمزیج وتصنیفھ تم طحن . الومینا وبنسب مختلفة %.٢٠) ١٠٦ – ٧٥(والخشنة قطرات قلیلة من الماء بإضافةالكبس شبھ الجاف باستخدامالنماذج تم تشكیل و. الصخور السینیة للتعرف على تركیب ةاستخدمت تقنیة حیود االشع ، )والمسامیة، الكثافة، ش الخطياالنكما(الخصائص الفیزیائیة . ة ساعتین درجة مئویة لمد ١١٠٠تم تلبیدھا بدرجة حرارة ھذه النماذج. مادة رابطة بوصفھا .تم قیاسھا لكل النماذج المحضرة ، )والحرارة النوعیة، االنتشاریة، التوصیلیة الحراریة(والخصائص الحراریة لھذه أعالهوقیمة العوامل المذكورة .االلومینا والمغنیسیا للصخور الطبیعیة لھا تأثیر محدود إضافةوان ، الكثافة تتأثر بالخصائص الحراریة إنالنتائج أثبتت .أخرىصھر المعادن وتطبیقات أفرانحراریات لتبطین بوصفھا الصخور الطبیعیة ھي بالمستویات التي تؤھلھا لالستخدام pdf created with pdffactory trial version www.pdffactory.com mailto:amelmerzah@gmail.com http://www.pdffactory.com http://www.pdffactory.com <4d6963726f736f667420576f7264202d20dfc7e3e120e6dac8c7d320e6e3c7e5d1> al-khwarizmi engineering journal al-khwarizmi engineering journal,vol. 13, no. 4, p.p. 5868 (2017) effect ti/altin multilayer coating on the crater wear process of cutting tool and tribological properties kamil j. kadhim* abbas allawi abbas** maher ali hussein*** *, ** ,*** al-furat al awsat technical university / musaib technical institute * email: kamil_jawad35@yahoo.com ** email: abbas_alawi80@yahoo.com *** email:maher.a.hussein@gmail.com (received 21 february 2017; accepted 17 july 2017) https://doi.org/10.22153/kej.2017.07.005 abstract tool wear is a major problem in machining operations because the resulting material loss gradually changes of the machine tool. there many factors may leads to material loss like; friction, corrosion, and also it’s happened by rubbing during machining processes between the work piece and the tool. dimensional accuracy of the work piece, and also the surface finish will be reducing by tool wear. it can also increase cutting force. in this study, we focused on the effect of the coating process on crater wear problems. crater wear is caused by the flow between the chip and the rake face of the tool, whereas flank wear is caused by the contact between the tool and the work piece. in reducing crater wear, aluminum titanium nitride (altin) using al0.67 ti0.33 in cathodic arc plating system is considered effective as a tools coating material. in reducing flank wear, altin is also deemed as the best tool coating material. experimentally, the use of ti/altin-coated tools has been proven effective in reducing crater wear. in this study, the roughness ra values of the (ti/altin) coatings were (0.14, 0.15, 0.23, 0.02, 0.21) µm at values of layers thickness (1.138, 1.518, 1.735, 2.717, 3.0818) µm, respectively. the lowest cof appeared at thickness 2.717 µm and the high coefficient of friction of the ti/altin coating was a result of high roughness and the large contact surface area of the system coating steel ball. the two most important parameters used to measure crater wear are length and width of wear. keywords: tool life, work piece, crater wear, altin, cof. 1. introduction tool wear is a major problem in machining operations. according to [1], tool wear is a gradual change in the shape of the machine tool as a result of material loss. material loss occurs because of friction, abrasion, and the rubbing process that take place between work piece and the tool. during machining. tool wear results from progressive loss and the degradation of the machining tool material. tool wear may decrease many important properties in the work piece like surface finish, dimensional tolerance, and accuracy. moreover, tool wear may increase machining forces and decrease the production efficiency of the work piece [1, 2]. tool wear may also increase the vibrations of the production machine during operation as well as the temperature at the contact points between the tool and the work piece. researchers have identified tool wear as the dominant problem in the life of machine tools. therefore, reducing the wear of machine tools enhances their life span. although cutting fluids are commonly believed to be capable of reducing tool wear, a research has shown that these fluids do not necessarily reduce the wear of machine tools [2]. the applications of tin coatings and their properties have been wildly explored by many researchers. other thin coatings are usually added to prolong the life span of the elements comprising industrial parts, such as al, ti and cr, as well as to increase oxidation kamil j. kadhim al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 5868 (2017) 59 resistance at temperatures above 450°c. in engineering applications tialn coatings was developed to be an alternative to tin coatings [68]. the next logical step in improving properties (high coefficient of friction [cof] and refractoriness) is to develop tial -based coatings as thermal barriers [9]. in fact, further research has indicated that cutting fluids can promote tool wear [3]. two common methods have been proven effective in reducing tool wear [910].these methods are the operation of the machine under conditions that cause lower tool wear and the tool and the incorporation of wearresistant materials into the machine tool. ti/altin coatings using al0.67ti0.33 cathodes in a cathodic ion plating system are report on in this paper. the effects of thickness layer on the mechanical properties of the coatings, and modulation period are determined. 2. experimental details the multilayer coating of cutting tools using ti/altin is important in improving cutting tools and their life span (figure1: a & b). arc system technology was developed by j&l technology korea (model legend: h.i.p iii) are conducted in this experimental study. this system are involves from four rounds alti 0.67: 33% target and four ti targets diameter of (15 ×150) mm. the holder of substrate jig contains from triple rotations with six axes, as shown in figure 1. the thermocouple is located at the back of the substrate jig holder with high, mid, and low levels from top to bottom. the distance between the thermocouple and the substrate holder is approximately 20mm – 30mm. (a) (b) fig. 1. (a) pvd in cathodic arc plating system technology sophisticated by j&l korea (model legend: h.i.p iii). (b) substrate holder outside coating chamber. this is feedback loop in the chamber regulates the power of the induction heater for temperature control. with the presence of nitrogen gas in the coating chamber; altin coating will deposited on the substrate, and by the bombardment of argon ion; the arc of the target material (ti and alti) will induced. the substrate is a wc square cutting insert that measures (3.18× 12.7 × 12.7) mm. figure 2). prior to coating, the cutting insert underwent ultrasonic cleaning with a detergent bath using different detergents and cleaning durations, as shown in table1. the rotating turntable is holding the cutting insert with5 rpm rotation speed, and the approximate distance from the target to the substrate is 50 mm. the experiment of coating process consists from six stages: they are pumping, main layer coating (alti), cooling, heating, ion etching, and buffer layering (ti). the minimum value of pressure which required in this process is (5 × 10−5) mbar. a process setting for the six stages was included. table (1) listed in detail all the multilayer coatings parameters. kamil j. kadhim al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 5868 (2017) 60 table 1, parameters for the arc ion plating of altin multilayer coatings. step process parameters 1 pumping rotary pump, root pump and turbo molecular pump 2 heating induction heater for heating the substrate up to the set process temperature 3 ar bombardment and ion cleaning ultimate vacuum=5.0×10-5 mbar, bias voltage = 900vwith 80% duty cycle, argon gas flow = 100 sccm, arc source current = 100a,time= 30 mins, temperature =380 c° 4 buffer layer bias voltage = 30v, nitrogen gas flow = 300 sccm, arc source current=100a, time = 10 mins, temperature = 380 c° 5 main layer altin multilayer coating deposition bias voltage = 40v, nitrogen gas flow = 600 sccm, arc source current 80a, time = 45 mins, temperature = 380 c° 6 cooling down and venting natural cooling for 30min at 100 ◦c 3. altin coating deposition the parameters setting for main altin coating layer deposition processes are shown in table 2. the figure 2 shows all details in of the flow for coating deposition process and more specification and function both operation elements. table 2, main layer parameters 40 v bias voltage 600 sccm nitrogen gas flow 80a arc source current 45,80,100,120,and 135 minutes time 380c° temperature the complete deposition procedure has been described earlier. a summary of the deposition parameters can be seen in table 3. fig. 2. schematic diagram of the arc ion plating system. after the completion of the coating process, the coated tools were cooled in the chamber naturally for 60 minutes. table 3, deposition parameters rotation speed rpm altin deposition time (min) total layer thickness (μm) ar gas flow rate (sccm) bias voltage (−v) buffer layer (min) n2 gas flow rate (sccm) etching (min) substrate temperature (c°) 5 45 2.717 100 40 10 600 30 380 5 80 3.089 100 40 10 600 30 380 5 100 3.912 100 40 10 600 30 380 5 120 5.815 100 40 10 600 30 380 5 135 8.760 100 40 10 600 30 380 kamil j. kadhim al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 5868 (2017) 61 4. pretreatment of substrate the cutting insert must be cleaned before coating by ultrasonic with a detergent bath for different mixed detergent and time as shown in table 4 using ultrasonic system shown in figure 3. di) water: the processed and pure water, or mechanically filtered to be cleaned and ready for consumption. the most common forms of purified water is distilled water and deionized (di). fig. 3. the cutting insert was cleaned by ultrasonic with a detergent bath for different mixed detergent and time. 5. study on crater wear to understand this type of tool wear, reviewing the geometry of machine tools is important. figure 4 illustrates the general geometry of a turning tool. table 5 present the geometry of the turning tool. the tool angle affects tool wear and the life span of the tool [3]. crater wear results from the erosion of the rake face caused by cutting chips. the figure below illustrates the chip flow in orthogonal cutting. fig. 4. tungsten carbide cutting tool insert commercially made by sumitomo. table 5, sumitomo spgn120208s cutting tool dimensions table 4, cleaning procedure tank # solvent time (sec) temperature (�� condition 1 ht1401(1) + ht1170 + di water 300 52 rotation 2 ht1401 + ht1170(2) + di water 300 52 rotation 3 di water spray & rotation 4 ht1233(3) + anticorr + di water 150 52 rotation 5 di water ultrasonic & rotation 6 di(4) water (rinsing) rotation sumitomo spgn120308s dimension: • d = 12.7mm • s = 3.18 mm • re = 0.8 mm kamil j. kadhim al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 5868 (2017) 62 figure 5a clearly shows that the chip flows over the rake face of the cutting tool during machining .the contact between the rakes face and the chip causes high friction at the interface. consequently, continuous flow can increase friction that leaves a scratch or scar on the face of the tool, which is usually parallel to the cutting edge of the tool [4]. this scar is generally in the form of a crater, hence the term crater wear. crater wear increases the rake angle, which in turn reduces the cutting force. however, crater wear weakens the tool cutting edge and thus reduces its strength [5]. the (figure5a) illustrates crater wear on the rake face of a cutting tool. figure 5(b) shows the variables that usually characterize crater wear. the most important parameter for wear characterization is crater depth (��). studies on crater wear show that the spindle speed of the cutting machine has an indirect relationship with crater wear [4]. extremely low spindle speed causes chip buildup on the rake face. this buildup increases friction, which causes the formation of a crater on the rake surface. the figure below illustrates the effect of cutting speed on crater wear and tool durability. figure 6 shows that increase in cutting speed reduces crater wear, thereby increasing the tool life. (a) (b) fig. 5. characteristics of crater wear. the variation in crater wear with time is shown in figure 6. three stages of wear can be identified. the wear rate in first stage is small, but this wear will increase gradually to become in average value. in third stage, the rate of wear will be very fast and decrease the tool life. in stage 1, tool wears ranges from 0 µm to 1.8 µm only within 0 to 10 min of machining. in stages 2 and 3, we found that; when the machining time increases, the crater wear will increase. in this case the approximating time for tool fails during machining is about (35) minutes. 6. results and discussion 6.1: types of tool wear and how to measure them friction between the tool and the work piece during cutting/machining generates high stresses and produces a wear pattern on the flank and the rake faces of machine tools [6]. crater and flank wears are the most significant types of wear. as discussed previously, crater wear occurs on the rake surfaces of tools (figures 5 to 8). four parameters characterize or measure crater wear [5,7], as shown in figure 8. these parameters include crater depth, width, and distance from the beginning to the middle. depth is the most widely used parameter for evaluating and measuring crater wear. it is typically used to determine the effect of cutting speed on crater wear. the figure below illustrates the effect of speed on crater wear. figures (7, 8) and characterizes the cutting time, depth, and width of the crater parameters. kamil j. kadhim al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 5868 (2017) 63 fig. 6. effects of cutting speed on crater wear depth. [14]. fig. 7. width and depth as measurements of crater wear. using tool geometry and crater parameters (as shown in the figure 8,a), [4] proposed the following equations (equation 1) for measuring crater wear in machine tools mathematical and the optical microscope(figure 8, b). in this paper the crater wear was calculated using the optical microscope method. thickness measurements were conducted on a brittle fracture surface of a sample. sem micrograph of the evaluated coatings together with energy dispersive x-ray analysis (edx) which was performed in nitrogen atmosphere to determine the elements contents in substrate as such shown in figure 9. �� � � � �� �� � ��� � …(1) where � � radius � �contact length. (a) (b) fig. 8. (a): estimating dimensions of crater wear arithmetically. (b): optical microscopy used in of measured crater wear in this paper. kamil j. kadhim al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 5868 (2017) 64 (a) (b) (c) (d) (e) fig. 9. a, b, c, d, and e brittle fracture (micrograph) and sem/edx spectrum of ti/altin, thickness 1.183 to 3.081µm kamil j. kadhim al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 5868 (2017) 65 6.2. tribological properties figure 10: shows the cof of the sliding time for the tin/altin multilayer coatings and the tungsten carbide specimen at room temperature. after 0 s to 200 s, the cof of the substrate reached 0.63. given the extreme hardness at the thickness layers of 3.0818 µm, the wear process was deemed stable. however, the tin/altin coatings at the thickness layers of 1.735 µm notably exhibited low hardness, which indicated that their wear resistance was better than that of other tin/altin coatings . fig. 10. cof of ti/altin multilayer coating of substrate with different thickness layers. there are some of wear scar will appear at a thickness layer of (3.0818) µm on the multilayer coatings deposited surface of the ti/altin. normally a transferred layer will cover the wear scar, which was composed mainly of fe and several fe oxides (as shown in table 6).using energy dispersive x-ray analysis (edx) which was performed in nitrogen atmosphere to determine the elements contents in substrate as such shown in table 6. table 6, elements of the wear debris of ti/altin multilayer coatings at thickness layer of 3.0818 µm. element wt.% at. % o 23.34 50.91 ti 11.36 8.28 fe 65.30 40.81 the hardness of ti/altin coatings is very high relative to the hardness of gcr15 debris ball which generated during the wear process. due to tribo-oxidation happened in this process, the wear debris was accumulated, entrapped and broke into minute fragments [11–13]. some large wear scar will appear on the surface due to debris adhered by coating (a) (b) 0 200 400 600 800 1,000 1,200 1,400 1,600 1800 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 time (sec) c o f th=1.183µm th=1.518µm th=1.735µm th=2.717µm th=3.081µm kamil j. kadhim al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 5868 (2017) 66 (c) fig. 11. shown 3d zoom 20x, the optical microscope have been used to observe the morphology of the wear track and wear debris. (a) prepare specimen before dispersion (b) the wear track, (c) 3d for wear. figure 12: presents the cof of the evaluated coatings based on sliding distance. the cof of the ti/altin coating grew markedly after traveling 7 and 15 m and then reached its maximum. in the case of the altin coating, cof gradually rose to its maximum. the cof of the altin coating grew linearly after traveling 18 m and then gradually reached its maximum. the cof was influenced mainly by roughness ra, coating hardness, and contact surface area. the figures above show the width of the wear track a, which demonstrates good agreement with the volume loss of the evaluated coatings. wear– coating volume loss was lowest for the altin coating at a thickness of 1.138 um. meanwhile, the cof values of the altin coating were the highest ones. increasing in contact area between the coating–counter-specimen systems is the main cause of cof growth. the wear of the counterpart was not investigated. fig. 12. profile of the cross sections of the wear tracks of ti/altin coating after pin-on-disc testing: a, width; b, depth; and r4, radius of sliding track. kamil j. kadhim al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 5868 (2017) 67 7. conclusion tool wear is the main problem in machining operations. it is characterized by a gradual change in the shape of the machine tool resulting from material loss. material loss is caused by the friction, abrasion, and the rubbing process that take place between the tool and the work piece during machining. tool wear results from progressive loss and the degradation of the material of the machining tool. it decreases the dimensional accuracy and surface finish of the work piece and increases cutting forces. crater wear occurs because of the contact between the chip flow and the rake face of the tool. flank wear occurs because of the contact between the tool and the work piece. ti/altin is the best tool coating material for reducing crater wear and flank wear. the depth and width of the wear are the most significant parameters in measuring crater wear. researchers have developed several models for the measurement of crater and flank wear in machine tools. the effect of thickness layer on crater wear and the tribological wear properties of ti/altin multilayer coatings were investigated in this work. the roughness ra values of the ti/altin coatings were 0.14, 0.15, 0.23, 0.02, and 0.21 µm at thickness layers of 1.138, 1.518, 1.735, 2.717, and 3.0818 µm, respectively. the high cof of the altin coating was a result of high roughness and the large contact surface area of the system coating ball. minimum values of surface roughness will reach 0.02 µm at a thickness layer of 2.717 µm. 8. references [1] p.s. sivasakthivel, m. v. vel, and r. sudhakaran, “prediction of tool wear from machining parameters by response surface methodology in end milling”, international journal of science and technology, vol. 2, no. 6, pp. 17801789,2010. [2] h. zhao, g.c. barber, and q. zou, “a study of flank wear in orthogonal cutting with internal cooling”, wear, vol. 253, pp. 957-962, 2002. [3] k.h.w. seah, x. li, and k.s. lee, “the effect of applying coolant on tool wear in metal machining”, journal of material. process. technol., vol. 48, p. 495, 1995. [4] h. yong, and g. dawson, “tool crater wear depth modeling in cbn hard turning” wear, vol. 258, pp. 1455-1461, 2005. [5] j. manigaj, s. velappan, s. nallathambhi, a.v. subbiah, and m. jacob,“experimental investigation on effect of tool crater wear and surface roughness in tin coated wc tool while machining martensitic stainless steel”, high temperature materials and processes, vol. 30, no. 3, pp. 257-265, 2010. [6] a. y. erry, r. muhammad, h. muataz, a. delvis, and rosehan,“ tool wear surface finish investigation in high speed turning using cermets insert by applying negative rake angles”, european journal scientific research, vol.38,no. 2, pp. 180-188, 2009. [7] a. otieno, p. chandhana, w. pedapati, and z. haiyan, “imaging and wear analysis using machine vision”, in proceedings of the 2006 ijmeintertech conference, pp. 2350,2006. [8] j. pelleg, l.z. zevin, s. lungo, n. coritoru, reactive-sputter-deposited tin films on glass substrates, thin solid films , pp. 117-197, 1991. [9] milošev, h.-h. strehbtow, b. navinšek. comparison of tin, zrn and crnhard nitride coatings: electrochemical and thermal oxidation, thin solid films pp. 246-303,1997. [10] b. major, r. major, f. bruckert, j.m. lackner, r. ebner, r. kustosz,p. lacki. new gradient coatings on tin and ti(c,n) basis for biomedical application to blood contact; advances in materials science 3(13), 7, pp. 63-70, 2007. [11] a.i. kovalev, d.l. wainstein, a.y. rashkovskiy, g.s. fox-abinovich, k. yamamoto, s. veldhuis, m. aguirre, b.d. beake.impact of al and cr alloying in tin-based pvd coatings on cutting performance during machining of hard to cut materials, vacuum 84,pp 184– 187, (2010). [12] b. podgornik, b. zajec, n. bay, j. vižintin. application of hard coatings for blanking and piercing tools wear, 270,pp 850–856, (2011). )2017(58-68 ، صفحة4د، العد13دجلة الخوارزمي الهندسية المجلم كامل جواد كاظم 68 متعدد الطبقات على عملية تأكل عدة القطع وخصائص االحتكاك على سطحها ) ti/altin(تأثير طالء عباس عالوي عباس** ماهر علي حسين *** كامل جواد كاظم* جامعة الفرات االوسط التقنية المسيب /*,**,*** المعهد التقني kamil_jawad35@yahoo.com* البريد االلكتروني: abbas_alawi80@yahoo.com** البريد االلكتروني: aher.a.hussein@gmail.comm*** البريد االلكتروني: الخالصة في أداة القطع و سبب هذه تغير تدريجية في عمليات التشغيل الميكانيكي ألن الخسارة المادية الناتجة هو مشكلة رئيسعدة القطع تآكل يعد . تأكل عدة القطع يمكن أن تقلل أثناء عمليات التشغيل الخسارة المادية هو التآكل واالحتكاك، وعملية الفرك التي تحدث بين األداة وقطعة العمل وجودة تشطيب السطوح لقطعة العمل , وايضا يؤدي الى زيادة في قوة القطع المطلوبة . في هذه الدراسة، ركزنا على تأثير من دقة األبعاد كل جناح آسبب ظهور الحفرة هو تدفق الرايش على وجه وسطح العدة . في حين توعملية الطالء على مشاكل تأكل سطح العدة وظهور الحفرة. وقطعة العمل . ولتقليل من حفر التأكل على سطح العدة , عملنا على تحسين سطح عدة القطع بعملية ل بين االداة العدة يحدث بسبب االتصا وللحد من تأكل جناح عدة القطع ، .في نظام قوس كاثودي للطالء 0.33ti 0.67alباستخدام (altin)الطالء بإضافة نترات األلومنيوم التيتانيوم altinباستخدام طالءالفقد اثبت ان المطلية بعد اختبار وتشغيل عدة القطعايضا من أفضل المواد لطالء العدة. تجريبيا (altin)يعتبر ,0.23 ,0.15 ,0.14بعد عملية التشغيل هي )altinقيم خشونة السطح المطلي بل ( حيث كانت نتائجكل . آتعتبر فعالة جدا في الحد من الت 0.02, 0.21 µm 3.0818 ,2.717 ,1.735 ,1.518 ,1.138ميكرون بسمك طبقات µm . هر عند ظاقل معامل احتكاك على التوالي للجهاز خشونة العالية ومساحة االتصال الواسعة بين الكرة الفوالذية الارتفاع معامل االحتكاك للطالء كان نتيجة علما ان . 2.717µm)سمك( .كلآفر التأكل هي العمق وعرض التاستخدمت لقياس حومنطقة الطالء .واهم العوامل التي (microsoft word \307\315\343\317 \346\321\307\306\317 \346\344\310\332112122) al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 14, no. 3, september, (2018) p.p. 112122 study the effect of cutting parameters on temperature distribution and tool life during turning stainless steel 316l ahmed a. akbar* raed r. shwaish** naba d. hadi*** *,**,***department of production engineering and metallurgy engineering/ university of technology *email: akbarthree@yahoo.com **email: raedshuishe@gmail.com ***email: nabaadhiyaa@gmail.com (received 19 september 2017; accepted 10 january 2018) https://doi.org/10.22153/kej.2018.01.007 abstract this paper is focused on studying the effect of cutting parameters (spindle speed, feed and depth of cut) on the response (temperature and tool life) during turning process. the inserts used in this study are carbide inserts coated with tialn (titanum, aluminium and nitride) for machining a shaft of stainless steel 316l. finite difference method was used to find the temperature distribution. the experimental results were done using infrared camera while the simulation process was performed using matlab software package. the results showed that the maximum difference between the experimental and simulation results was equal to 19.3 ℉, so, a good agreement between the experimental and simulation results was achieved. tool life was decreased when spindle speed and feed were increased. keywords: cutting parameters, finite difference method, stainless steel 316l, temperature distribution, tool life, turning operation. 1. introduction in metal cutting, amount of heat may be generated because of the friction at the tool– chip interface and plastic working of the solid. in the shear zone the metal is deformed plastically and removed in the formed of chip [1]. the deformation of the material elasticity demand energy these energy was storing in a material like strain energy, and no amount of heat was formed while the material was deformation plastically, generality the energy that utilized was transform to heat. at cutting process a materials were undergo at large amount of strain and the deformation of materials elastically were form a tiny of the ratio of all deformation. it should be suppose all amount of energy was transformed to a heat [2]. agree with to the 1st rule of thermodynamics, while work was converted to a heat, the amount of a heat generated was equal to the amount of work. heat produced during transformation of mechanical energy. there are three sources of heat during metal cutting are given below [3] and shown in fig. 1: 1.the shear zone, where the primary plastic or shear deformation takes place. 2.the chip-tool interface where secondary plastic deformation due to friction between the heated chip and tool takes place. 3.the work-tool. interface at flanks where frictional rubbing occurs (vf). fig. 1. sources of heat in metal cutting [3]. ahmed a. akbar al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 112122 (2018) 113 bartoszuk m. et al. [4] studied finite difference method-based simulation of temperature fields for application to orthogonal cutting of aisi 1045 steel with coated tools. v. astakhov et al. [5] studied influence of cutting parameters on life of tool for al 610 alloy, then showed that the best tool life is, obtained in lowest feed rate and lowest cutting speed combination. c. dinc et al. [6] developed the effectiveness for formerly (finite difference time domain) temperatures predictions models was hold out to orthogonal cutting process by using (ir camera). in the cutting conditions using orthogonal machining of (al 7075 and aisi 1050). naife a. talib [7] studied, the influence of (speed of cut, and rate of feed), on life of tools at fixed cut depth for low alloy steel without cooling fluid. a maximum life was at maximum speed of cutting, (66.88) m/min and rate of feed (0.72) mm/rev, while the cutting tool life was (388.3) min. sunday j. ojolo and o. ogunkomaiya [8] studied the influence of cutting condition on life of tool using dry condition. they used 3 cutting tools material first (hss), second tungsten carbide insert tool grade (p-10) (dmng), and third carbide insert tool (150412-sa) and the workpeice material mild steel. dhananchezian m. et al. [9] studied of machinability properties for machining austenitic (aisi 316 l) and super duplex (2505) stainless steel utilizing (pvdtialn) nano-multilayer inserts. the effects of speed of cut on the temperatures, force of cut roughness of surface, wear of tool wear and chip breaking were analyzed. oluseyi o. ajayi et al. [10] studied the development of thermo mechanical model for analysing effects of friction and cutting speed on temperature distribution during orthogonal machining of aisi 316 l.” 2. temperature in the shear plane suppose in the shear plane zone: 1. the shear stress is constant (uniform), 2. the heat is generation within the work material and passing through the shear plane is uniform, 3. the work material when passing through shear zone is immediately and uniformly heated up. the temperature of the work material is raises from the room temperature (tr) to the shearplane temperature (ts). the temperature increase (tstr) is obtained by dividing the shearing power, represents work (heat) in unit time, by the heat capacity of the material passing through the shear zone in unit time, which is the heat capacity of the metal removal rate q [11]: (ts − tr) = � � …(1) where; ps is shearing power (mw = nmm/sec), ρ is specific mass (kg/m3), and c is specific heat (nm/(kg . °c)). the product (ρc) represents “the specific heat per unit volume” may be given by using the following units: (ts − tr) � (���/�� ) ���(���)� (�� �� ⁄ ) � (� (��� ℃)⁄ )� …(2) where; b is chip width (mm), v is cutting speed (mm/sec), and h is chip thickness (mm). p�= f�v� = !"#$% "#$ (%&∅) ( "#$∅ let us denote d = "#$ (%&∅) "#$% "#$∅ then p� = f)vd = k$bhvd ts tr = + ���, ��� � = + , � …(3) where; k� is specific force (n/mm2). the shear-plane temperature proportional to the (ks) and inversely proportional to specific mass ρ and specific heat c. in this way, (ts) is determined by the mechanical and thermal properties of the workpiece only and it applies even to very slow cutting. while the power spent in the shear plane increases with chip thickness and speed, the flow rate of material through the plane that gets heated by that power increases in the same proportion. actually, because (ks) slightly decreases with chip thickness h, and cutting force f further decreases with cutting speed (v), the shearplane temperature partially decreases with the increase of both (h) and (v). in the chip tool interference that seen in fig. 2, the friction power is generated and it is distribution at a region linked, among a tool and a chips, that seen in fig. 2, the distribution of friction energy followed the normal pressure distribution of. in the numerical treatment we divide the chip into number of elements both in two direction. the (x) direction of the face of the tool and the (y) direction of the shear plane. the subscript for the former division is denoted k, and it starts with cutting edge where (k = 1) to the end, of the contact length (lc) where (k=kk) [11]. the tool pressure founded experimentally maximum & constant over the ahmed a. akbar al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 112122 (2018) 114 distance (h//2) from, the cutting edge and decrease linearly between this point and the end of contact [12]. the friction (pf) power can derive acting over the area (bδx) of the one slice. assume that the length of contact is proportional to the undeformed chip thickness (h1) [11]. fig. 2 . distribution of friction power over the rake face of the tool [11]. lc = mh1 m : number shows the amount of amplification. then �01 = 231� = ++ 1� ∆x and p�67 8++ 1� + / 1 kk :1 − / 1�<= = p> …(4) *for k≤ kk/2m, pb = p�67 *for ++ 1� < k ≤ kk pb = p�67 − ∆p :k − ++ 1�< … (5) where ∆p = �def++(/g/ 1�⁄ ) …(6) *for k> kk, pb = 0 3. computing the temperature field: the computing of temperature field are divided in two phase [11]: 3.1. phase 1: neglecting heat escaping through the tool: the heat convected of chips to the rounded air was suppose totally ignored, and never heat was conduction far away during the tool. a former assumption is quite realistic, while the latter introduced that will be computed and corrected in phase 2.both these assumptions mean that all heat is conducted away by the chip. fig. 3. a. the area of chip[11]. fig.3.a shows the area of chip abcd. the boundary conditions are along the ab shear plane the temperature is (ts), along ac and bd the chip is insulated, and along ac above (lc) where the (heat) inter because of the friction at chips-tool. the amount of force of friction and, the heating power are distributed as shown: it founded constant and maximum from the edge of cutting a along one over two the thickness of undeforming chips (h1) & then it lowering straightly towards the ending of a linked. heat spreads onto a chips using conductions and transfer of mass at orientation (x) and using conductions only at orientation (y). the whole field of the chip is divided into incremental slices in the two directions. in direction x are subscripted k, from (1 to kk) above length of contacts and up to a total of kkk. the slices in the direction y are subscripted from 1 to 20 by this way, the whole field is divided into 20 times kkk elements. by using the method of finite differences, we suppose a temperatures was fixed along all parts and alteration discretely for part to next part. boothroyd [2] found that mass transfer of heat in x is much more powerful than conduction. the latter can be neglected; it is sufficient to consider the former mode only. correspondingly, we will consider heat conducted in y direction and, heat moved by mass transfer in x direction. this is symbolically expressed by assuming that every vertical slice moves in direction x with the chip velocity (vc) while being insulated, in direction x, against the neighboring slices, as shown in fig.3.b, for the (kth) slice. instead of considering a steady-state, two-dimensional (x,y) heat transfer problem we formulate onedimensional (y) transient case. we will follow one vertical slice as it moves, in discrete increments of time, through positions from 1 to kkk. above the (lc), for (1 to kk) its obtain on it minimize ending the (pk) & the generated ahmed a. akbar al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 112122 (2018) 115 heats was diffusion in these slices at orientation (y), by conduction. between kk and kkk there is no more heat input. the temperature of every element tj,k varies through the steps 1 to kkk. under the assumption of no convection of heat out of the chip, the temperature in such a slice, far away from the end of the. contact zone, would approach a uniform, constant value. for practical purposes we choose the following. equation: kkk = k++ 1 …(7) the shear-plane temperature is found by using eq. (2), it will further be accepted that on average for most our demonstrations (lc = 4h1). the total heat flow over the area of the contact length (lc) times the chip width (b) equals the friction power (pf). pf= ff .vc where; ff is the friction force. fig. 3.b. finite-difference formulation for temperatures in the chip [11]. the heat flux distribution is as shown in fig.2, and it is expressed in eq. (4), (5), and (6) in the form of the power injected into each slice. the primary states of thermal fields onto the chips was like that in the slice where k = 1 have the uniforms shear-plane temperature: tl,/ = t� where j = 1 to 20 …(8) the lowest element j=1, at every instant k receiving input heat (pk) and losing heat by the conduction to neighbor part ( j = 2). excess heats was using for increased temperatures along (∆t) times instant for ( t/,+ t/,+&/ ) pb − (m0,ngm�,n∆o ∆xbk՝b ∆x ∆y ρc m0,nt0gm0,n∆) ) …(9) ∆t = ∆7 �3 = 23++ �3 … (10) the “conducted heat per time step ∆t from j = 1 to j = 2 is considered the second expression in the bracket on the left side of eq (9)”. it was relative for a temperatures gradients [vt/,+ − t1,+w/∆y�, for region [a = ∆xb � & for the (k՝) (thermal conductivity). the rights direction was (ρc) (heat capacity of parts). for element j = 2 to 19, in state heat input pb the inflow of heat for following minimize part was using: :mxy0,ngmx,n∆o − mx,ngmxt0,n∆o < ∆xbk՝ = b∆x∆yρc mx,nt0gmx,n∆) …(11) for, ( j = 20) a second expression at left side of eq. (11), was missing in order to heat was no conduction far away from part and no convection of heat far away the chips. eqs. (9) to (11) using to expression a temperature for times [(k+1)]: tl,+&/ = ⎩⎪ ⎪⎪ ⎨ ⎪⎪⎪ ⎧ 8 �^�∆7∆o� − vm0,ngm�,nw_ (∆o)� = ∆t + t/,+ , j = 1 vtlg/,+&/ + tl&/,+ − 2tl,+w _∆) (∆o)� + tl,+ , j = 2 − 19 vt/b,+&/ − t1c,+w _∆) (∆o)� + t1c,+ , j = 2 ⎭⎪ ⎪⎪ ⎬ ⎪⎪⎪ ⎫ ..(12) where α = k՝ ρc⁄ . in eqs. (12) the first expression on the right side of equations is subscripted (k + 1) and not k as could have been expected. this means that we are updating the temperature as soon as the new values of temperature are available, which lead to improves the convergence and stability of the calculation. the increment in time ∆t, eq. (10), shouldn’t be selected much large in order to the calculation in separated steps shouldn’t converge. this leads to a minimum value of kk for computational stability. 3.2. phase 2: correcting for heat escaping through the tool: the shape of the tool and the thermal field in it are strongly simplified, see fig.4, as follow: heat is generated first in shear plane (s) and then in the chip/tool contact. most of it is taken away by the chip, but some of heat flows through tools to the tools holder, and into the machine parts. it is assumed that: • amount of generated heat was convect and radiate through a tool onto air, then heat escaping into the air is neglected. • the tool escape from the area of cut was already at back ground temperature. • the isotherm at tools were upper or lower line for the equivalent displacement for the area of cutting. thus we will represent tools ahmed a. akbar al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 112122 (2018) 116 as a dowel within a (chips/tools) linked region at a roof apex. it should be spilt on slices within thickness. (∆zi), depth (b) (into the paper), and width (wi). • the thermals fields was a 1-dimension at (z), however each slice have a fixed temperatures everywhere. • while the bed (bottom) was at background temperatures (tr) and sides were isolated. for the points of vision of tools the heat over the (lc) was fixed. it should been possessed as equivalent to the rate of temperatures above contact length (lc). so we formulate a fixed (steady-state), (1 dimensional) problem. the temperature tcav is expressed in the equation below: t 6� = / ++ ∑ t/,+++/ …(13) fig.4.a: the general set up [11]. fig. 4.b. the finite-difference formulation diagram of the tool [11]. the temperatures (ti) of the individual slices do not change (steady state). all heat that entering the slice departure the slice. a power flux during a tools was (p)) & it was similar for all slices shown in fig. 5. the 1st step starts from the tool top (the linked among the tool and the chips) and then to middle of the slice top when temperature (ti), was location. the means width was equal: w/ = l + ∆l 1 …(14) for whole a following slices, we move from the slice middle to the next one middle distance is ∆z, & (wi) was equal by taken a together 40 layers: wm = lc + 2 (i 1) ∆z, (i = 2-40) …(15) a final slices stage leave for (tnc to) at a distance of (∆z/2): w41= l + 79.5∆z …(16) then we have p) = t 6� − t/∆z 2⁄ p w/ bk՝6, r/ = ∆z 2⁄ w/ p) = t/ − t1∆z p w1bk՝6, r1 = ∆z w1 p) = t/ − tm&/∆z p wmbk՝m, rm&/ = ∆z wm&/ p) = mr0gms∆l 1⁄ p wn/bk՝�, rn/ = ∆l 1⁄ tr0 …(17) where: k՝6 is thermal conductivity of tool. now, expressing the individual temperatures in terms of t 6� t/ = t 6� − p)bk՝6 r/ fig. 5. specification of die thermal field in the tool as steady-state single-dimensional [11]. t1 = t/ − �!�b՝e r1 = t 6� − �!� :u0b՝e + u�b՝e<…(18) tm&/ = tm − �!�b՝v rm&/ = t 6� − �!� ∑ uvb՝v m&// …(19) denoting r = ∑ uvb՝v n// …(20) to = t 6� − �!o � and p) = (t 6� − to) � o …(21) the "thermal resistance" r can be calculated by the dimensions and thermal conductivities of the tool. ahmed a. akbar al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 112122 (2018) 117 4. experimental work the experimental work were done by using universal turning type sinus 330/3000. (sn-126130). the inserts used in this paper is carbide inserts coated with tialn. fig.6 shows the machining operation and temperature. measurement. fig. 6. workpiece on the machine and temperature measurement using fluke camera. 4.1 the workpiece material the workpeice material is a shaft of stainless steel 316 l, which is inspected in central organization for standardization and quality control / lab. of quality control. the chemical composition and thermal properties are shown in tables (1) (2) respectively. the stainless steel shaft has diameter (74) mm. table 1, chemical composition of stainless steel 316l. table 2, thermal properties of stainless steel 316l and tool [13]. property values unit thermal conductivity of workpiece (w՝) 16.3 (w/m.°k) specific electrical resistivity 0.75 ω mm²/m specific heat at 20 x° 3.6 n/(mm².°c) thermal diffusivity 3.9 m1/s specific force thermal conductivity z{ |}~���� ����~� w ՝ a thermal conductivity z{ �zz� ��}�w w՝ b 2600 70 43 n/mm² n/s. °c n/s. °c 4.2 temperature measurement all temperature measurement were tested using (ircamera fluke) shown in fig. 7. the cutting parameters and experimental result of temperature are shown in table 3. the ir camera need some set before making the measurement like (emissivity, background temperature, time, date). the emissivity of any material was value of irradiation whose emanate proportional to the (pure black body). the black body was typical motive and a typically absorption as well. the emissivity value was (0 to 1). the emissivity of a black body is (1) [١4]. in this work the emissivity value is (0.05) and the value of background temperature is (30°c). fig. 7. ir-camera fluke table 3, cutting parameters and experimental results of temperature. spindle speed (r.p.m) feed (mm/rev) depth of cut (mm) temperature (℉) 400 0.1 0.5 843.1 500 930 630 943.4 800 957.5 1000 1031.1 400 0.1 0.5 843.1 0.12 941.8 0.14 961.6 0.16 977.5 0.18 980.7 400 0.1 0.5 843.1 0.7 915.1 0.9 960 1.1 966.3 1.3 995.6 4.3 tool life calculation tool life can be calculated by using taylor equations. the cutting parameters and experimental result of tool life are shown in table 4. the value of constant (ct and nt) can be metal wt% metal wt% c% 0.0044 cu% 0.597 si% 0.432 cr% 18.2 mn% 1.74 mo% 2.19 p% 0.0271 s% 0.0216 ni% 9.55 fe% balance ahmed a. akbar al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 112122 (2018) 118 calculated by using graphical methods as shown in fig.8. -nt = -1.4938 log ct = 3.8253 ct = 6688.05 use taylor equation to find tool life [15] vc × t�) = ct …(22) t = 17.95 min where: ct is constant and nt is exponent that depends on the cutting parameters. the equation used to find cutting speed shown below [16]: vc = � , � /ccc …(23) where: v" is cutting speed (m/min), n is spindle speed (r.p.m), and d is work diameter (mm). table 4, cutting parameters and experimental results of tool life. spindle speed (r.p.m) feed (mm/rev) depth of cut (mm) tool life (min) 400 0.1 1.1 17.95 500 15.45 630 13.27 1000 9.75 400 0.1 0.12 0.14 0.18 1.1 17.95 17.4 17.26 16.98 fig. 8. graphical method. 5. the results and discussion 5.1 the effect of cutting parameters on temperature the effect of spindle speed on the temperature shown in fig.9, it can be seen with increase the spindle speed the maximum temperature increase. the reason is when the spindle speed increase, the strain rate in the primary and secondary shear zone increased so the heat flux generated and cause the increase. the effect of feed on the temperature shown in fig.10. it can be seen with increase the feed the maximum temperature increase. the reason is the increase in the feed lead to increase the cross section of chips so the friction increase and making the increase in the maximum temperature. the effect of depth of cut on the temperature shown in fig. 11, it can be seen with increase the depth of cut the maximum temperature increase. the reason is when depth of cut increase the cross section of chip increase and lead to increase the friction so the temperature increase. 5.2 the effect of cutting parameters on tool life the effect of spindle speed on tool life shown in fig. 12, the tool life decrease when the spindle speed increase. the reason is when spindle speed increased the tool wear increase, and cutting time decrease lead to decrease tool life. the effect of feed rate on tool life shown in fig. 13, the tool life decrease when the feed rate increase the reason is when feed rate increase the amount of heat generated is increase so the cutting tool is subjected to quick collapse lead to decrease the tool life. fig. 9. effect of spindle speed on temperature. fig. 10. effect of feed on temperature. ahmed a. akbar al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 112122 (2018) 119 fig. 11. effect of depth of cut on temperature. fig. 12. effect of spindle speed on tool life. fig. 13. effect of feed on tool life. 5.3the comparison between the experimental and simulation results of temperature. the experimental result obtained from (ir-camera). the thermal image are produced by using smart view software version (3.1). high contrast colors scales was fitted to a picture. a simulation result produced by using matlab program to draw the temperature distribution using contour plot. the difference between experimental value and simulation value is difference= /experimental value – simulation value/ (a) (b) fig. 14. temperature fields of machining with spindle speed (400 r.p.m), feed (0.10 mm/rev), depth. (0.5m), (a) temperature distribution simulation, (b) experimental measuring of temperature using ir-camera. (a) (b) fig. 15. temperature fields of machining with spindle speed (500r.p.m), feed (0.1mm/rev), depth (0.5mm), (a) temperature distribution simulation, (b) experimental measuring of temperature using ir-camera. ahmed a. akbar al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 112122 (2018) 120 (a) (b) fig. 16. temperature fields of machining with spindle speed (400 r.p.m), feed (0.12 mm/rev), depth (0.5 mm), (a) temperature distribution simulation, (b) experimental measuring of temperature using ir-camera. (a) (b) fig.17.temperature fields of machining with spindle speed (400 r.p.m), feed (0.18 mm/rev), depth (0.5 mm), (a) temperature distribution simulation, (b) experimental measuring of temperature using ir-camera. (a) (b) fig. 18. temperature fields of machining with spindle speed (400 r.p.m), feed (0.10mm/rev), depth (1.3 mm), (a) temperature distribution simulation, (b) experimental measuring of temperature using ir-camera. 6. conclusions the main concluded of the present work are the following 1.ir-camera is the best way to measure the temperature because it is easy to install and give the result with good accuracy”. 2.the relationship between the maximum temperature and tool life, when the temperature increase the tool life decrease. 3.the maximum temperature of stainless steel aisi 316l is (1031.1℉) at spindle speed (400 r.p.m), feed (0.1 mm/rev), depth of cut (0.5 mm). 4.the maximum difference between the experimental value and simulation value is (19.3℉). so the results shows a good agreement with the simulation value. ahmed a. akbar al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 112122 (2018) 121 7. references [1] t. d. marusich, m. ortiz, “modeling and simulation of high speed machining”, international journal numerical methmatical engineering, vol. 38, 1995, pp. 3675-3694. [2] boothroyd, g., ”fundamentals of metal machining and machine tools” international student edition, mc graw hill international book company tokyo, 1981, pp.109. [3] a. bhattacharyya, i. ham, ”design of cutting tool use a metal cutting theory, 1st edition, astme p. committee, 1969, pp. 347. [4] m. bartoszuk, w. grzesik, p. neslony, “finite difference method-based simulation of temperature fields for application to orthogonal cutting”, international journal of machining science and technology, vol.9, issue 4, 2005, pp. 529-546. [5] v. astakhov, “effects of the cutting feed, depth of cut, and workpiece (bore) diameter on the tool wear rate,” international journal of advanced manufacturing technology, vol. 34, issue 78, 2006, pp. 1-10. [6] c. dinc, i. lazoglua, a. serpenguzel, “analysis of thermal fields in orthogonal machining with infrared imaging”, jornal of materials processing technology, vol. 98, 2008, pp.147 154. [7] naife a. talib, “studying the effect of cutting speed and feed rate on tool life in the turning processes”, diyala journal of engineering sciences, special issue, 2010, pp.181-194. [8] sunday joshua ojolo and olugbenga ogunkomaiya,” a study of effects of machining parameters on tool life”, international journal of materials science and applications. vol. 3, no. 5, 2014, pp. 183-199. [9] dhananchezian m. thinesh t, steven niketan paul and inian roy a, “study of machinability characteristics for turning austenitic (316l) and super duplex (2505) stainless steel using pvd-tialn nano-multilayer inserts”, arpn journal of engineering and applied sciences, vol.11, no.2, 2016. [10] oluseyi o. ajayi, abatan abiola, mercy ogbonnay, agarana michael, “development of thermomechanical model for analysis of effect of friction and cutting speed on temperature distribution around aisi 316 l during orthogonal machining”, international conference on sustainable materials processing and manufacturing, 2017, pp. 682-687. [11] george tlusty, “manufacturing process and equipment”, first edition, 2000, prentice hall. [12] a. and yellowley i. , “process detection of tool failure in milling using cutting force model”, journal of manufacturing science and engineering”, 1989, 111(2), pp. (149157). [13] www.stainless steel 316l [14] v. dessoly, “modeling and verification of cutting tool temperatures in rotary tool turning of hardened steel”, master thesis, mechanical engineering, georgia institute of technology, 2004. pp.(67). [15] j. paulo davim, “machining of hard materials”, springer-verlag london limited, 2011, pp.54. [16] m. p. groover, “fundamentals of modern manufacturing”, third edition, lehigh university, 2007, pp. 509. )2018( 112-122، صفحة 3د، العد14دجلة الخوارزمي الهندسية المجلم احمد علي اكبر 122 تشغيل الفوالذ درجة الحرارة وعمر االداة اثناء دراسة تاثير معامالت التشغيل على توزيع 316lالمقاوم للصدأ ***نبع ضياء هادي **شويشرائد رشيد *احمد علي اكبر يةالتكنولوجقسم هندسة االنتاج والمعادن/ الجامعة ،**،*** * akbarthree@yahoo.com :البريد االلكتروني * raedshuishe@gmail.com :البريد االلكتروني ** nabaadhiyaa@gmail.com :البريد االلكتروني *** :الخالصة اثناء عمق القطع) على االستجابة (درجة الحرارة) ( عمر االداة) و التغذيةو يرتكز هذا البحث على دراسة تاثير معامالت التشغيل مثل (سرعة الدوران 316) لتشغيل عمود الفوالذ المقاوم للصدأ titanum aluminum nitride)) (tialn ـعملية الخراطة. اللقمة المستخدمة هي لقمة كاربيدية مصبوغة ب lة تمت بااستخدام . طريقة الفرق المحدد استخدمت اليجاد التوزيع الحراري. النتائج التجريبية تمت بااستخدام كاميرا االشعه تحت الحمراء وعملية المحاكا ً ) . لذلك اظهرت توافق℉19.3( برنامج ماتالب. النتائج بينت ان اعظم فرق بين النتائج التجريبية والمحاكاة هي بين النتائج التجريبية والمحاكاة. عمر اً جيد ا .االداة تقل بزيادة سرعة القطع والتغذية 3746 al-khwarizmi engineering journal,vol. 11, no. influences of the twisted plate jafar m. hassan* mohammed f. mohammed*** *,**,*** department of mechanical engineering / university of technology *** (received abstract in order to enhance the efficiency and with low additional cost, twisted used for test. family of twisted strips are inserted inside each collector risers with different twisted ratios (tr=3,4,5). the collectors are connected in parallel conditions (solar radiation and ambient transfer rate occurs at twisted ratio (3) . solar collector at different flow rate keywords: twisted strip, solar collectors 1. introduction extensive researches, both numerically and experimentally had been conducted on the operating and performance study of thermosyphon and forced circulation on the solar water heating systems. these studies, however, were mainly focused on the design and optimization of the overall system with little attention given to study the thermofluid behavior inside the collector. in recent years, many techniques have been proposed for enhancement of the heat transfer rate. these can be classified into two main groups: passive technique not requiring additional power sources and active technique requiring additional external power inputs. in the case of the passive technique, convection heat transfer from surfaces with attachments of different solid shapes geometries, such as baffles, fins, ribs, twist strips, have been exploited, especially; twisted strip khwarizmi engineering journal,vol. 11, no. 3, p.p. 3746(2015) wisted strips insertion on the performance of late water solar collector jafar m. hassan* qussai j. abdul-ghafour mohammed f. mohammed*** department of mechanical engineering / university of technology *email: jafarmehdi1951@yahoo.com **email: kaisygj@yahoo.com *** email: mohammed2007msc@yahoo.com (received 19 november 2014; accepted 31 march 2015) efficiency of flat plate solar water collectors without changing additional cost, twisted strips are inserted inside its riser pipes. three flat plate collectors are twisted strips are inserted inside each collector risers with different twisted ratios the collectors are connected in parallel mode (z-configuration) and are exposed to the same conditions (solar radiation and ambient temperature) .the experimental results show occurs at twisted ratio (3) .consequently, for the same twisted ratio the flow rate used (60,100 and 150) ℓ /hr. were 49 %, 57% and 63% solar collectors. extensive researches, both numerically and experimentally had been conducted on the operating and performance study of thermosyphon and forced circulation on the solar water heating systems. these studies, however, were mainly focused on the design and ptimization of the overall system with little attention given to study the thermofluid behavior in recent years, many techniques have been proposed for enhancement of the heat transfer rate. these can be classified ps: passive technique not requiring additional power sources and active technique requiring additional external power inputs. in the case of the passive technique, convection heat transfer from surfaces with attachments of different solid shapes at different geometries, such as baffles, fins, ribs, twist strips, have been exploited, especially; twisted strip which is widely used in many industries experimental investigations of twist coil for enhancing heat transfer and efficiency have been being appeared experimentation both strip and wire coil that’s carried out in the range of reynolds number from (5000 – 45,000) and prandtl number from (0.7 30). the maximum heat enhancement for twisted strip and wire coil insert is 3.5 and 2.0 times higher than the plain one. twisted strip insertion on heat transfer and flow friction characteristics in a concentric double pipe heat exchanger have been studied exp by watcharin et al. [2] introduced by using twisted strip placed inside the inner test tube of the heat exchanger with different twist ratios (tr=5,7). the experimental results revealed that the increase in heat transfer the twisted-strip inserts is found to be strongly influenced by strip-induced swirl generation or vortex motion. over the range investigated, the al-khwarizmi engineering journal (2015) erformance of flat ghafour** department of mechanical engineering / university of technology changing in its original shape three flat plate collectors are twisted strips are inserted inside each collector risers with different twisted ratios are exposed to the same ental results show that, the highest heat daily efficiencies for the 57% and 63% respectively. which is widely used in many industries. the experimental investigations of twist strip and wire for enhancing heat transfer and efficiency have been being appeared by rose and briggs [1] xperimentation both strip and wire coil that’s carried out in the range of reynolds number from 45,000) and prandtl number from (0.7– enhancement for twisted strip and wire coil insert is 3.5 and 2.0 times higher than the plain one. influences of the twisted strip insertion on heat transfer and flow friction characteristics in a concentric double pipe heat exchanger have been studied experimentally ] the swirling flow was introduced by using twisted strip placed inside the inner test tube of the heat exchanger with different . the experimental results increase in heat transfer rate of strip inserts is found to be strongly induced swirl generation or vortex motion. over the range investigated, the jafar m. hassan maximum nusselt numbers for using the enhancement devices are (188%) and (159%) respectively, higher than that for the plain tube. alireza and kamran [3] study experimental impact of heat enhancement devices on the thermal performance of single-tube flat solar collector. different passive heat enhancement devices that include twisted strip, coil-spring wire and conical ridges were studied. the flow rate is close to the typical flow rates in thermosyphon (natural). the comparison showed that the heat enhancement devices are ineffective in enhancing heat transfer rate in the studied range and geometry. nagarajan et al. [ experimentally the heat transfer and friction factor characteristics of solar parabolic through collector fitted with full length twisted strips inserts of twist ratio (6, 8 and 10) have been presented. the transitional flow regime is selected for this study with the reynolds number range (1192 to 2534). the experimental data obtained were compared with those obtained from plain tube published data. the effects of full length twisted strip inserts on heat transfer and friction factor were presented. the heat transfer coefficient enhancement for twisted inserts is higher than that for plain tube for a given reynolds number. herrero m. et present an enhancement techniques applied to flat-plate liquid solar collectors towards more compact and efficient designs. tu enhancement passive techniques can consist of adding additional devices which are incorporated into a smooth round tube (twisted strips, wire coils), modifying the surface of a smooth tube (corrugated and dimpled tubes) or making special tube geometries (internally finned tubes). for the typical operating flow rates in flat collectors, the most suitable technique is inserted devices. this type of inserted device provides better results in laminar, transitional and low turbulence fluid flow regimes. akeel [6] study the heat transfer in a horizontal tube by means of six types of twisted tape inserts for the range of reynolds number extends from 4500 to 23500 as follows : normal twisted tape regularly spaced twisted tape, triangular-cut twisted tape, rectangular-cut twisted tape, semicircular twisted tape, and drilled twisted tape. the experiential results show that the enhancement of heat transfer increases as the type of twisted tape changes from one to six, respectively. and amnart [7] present a numerical analysis of laminar fully developed periodic flow and heat transfer in a constant temperature circular tube with single twisted tape inserted. the twisted tape is introduced and inserted in the al-khwarizmi engineering journal, vol. 11, no. 3, p.p. 38 maximum nusselt numbers for using the enhancement devices are (188%) and (159%) han that for the plain tube. xperimentally the impact of heat enhancement devices on the tube flat-plate different passive heat enhancement devices that include twisted strip, spring wire and conical ridges were studied. the flow rate is close to the typical flow rates in comparison showed the heat enhancement devices are ineffective in enhancing heat transfer rate in the studied range [4] investigate heat transfer and friction factor characteristics of solar parabolic through collector fitted with full length twisted strips inserts of twist ratio (6, 8 and 10) have been presented. the transitional flow regime is selected for this study s number range (1192 to 2534). the experimental data obtained were compared with those obtained from plain tube published data. the effects of full length twisted strip inserts on heat transfer and friction factor were presented. ent enhancement for twisted inserts is higher than that for plain tube for herrero m. et al. [5] nhancement techniques that be plate liquid solar collectors towards more compact and efficient designs. tube-side enhancement passive techniques can consist of adding additional devices which are incorporated into a smooth round tube (twisted strips, wire coils), modifying the surface of a smooth tube (corrugated and dimpled tubes) or making special tries (internally finned tubes). for the typical operating flow rates in flat-plate solar collectors, the most suitable technique is inserted this type of inserted device provides better results in laminar, transitional and low akeel and ameer in a horizontal tube by tape inserts for the range of reynolds number extends from 4500 to twisted tape regularly cut twisted tape, cut twisted tape, semicircular-cut twisted tape, and drilled twisted tape. the experiential results show that the enhancement of heat transfer increases as the type of twisted tape changes from one to six, respectively. withada a numerical analysis of laminar fully developed periodic flow and heat transfer in a constant temperature-surfaced circular tube with single twisted tape inserted. the twisted tape is introduced and inserted in the middle of the tested tube. the effects of twisted ratios (1, 2, 3, 4, 5and 6) are presented for reynolds number values ranging from re = 100 to 2000. they found that the heat transfer in the circular tube with the twisted tape is more effective than that with no twis the increase in the twist ratio leads to decrease in the nusselt number and friction factor. objective of the present work is to enhanced the performance of the flat plate solar collector by inserting twisted strips with r the task was accomplished by connecting three collectors in (z-configuration) different flow rates. 2. experimental work 2.1. experimental test rig the experimental test rigs consist of three identical flat plate solar collectors, each one with absorbing area (80cm * 120cm) with one glass cover as shown in fig. 1. also equally spaced (10cm) parallel copper riser pipes of (10.5mm inner and 11mm outer (1200mm) length. these pipes are connected with two headers, one on each end. the joints between headers and copper pipes ends are made by adapter screws as shown in purpose of these adapter screws is f separating of riser pipes from the headers to inserting twisted strips inside them. a copper sheet with (0.5mm) thickness is used as the solar radiation absorber as shown in fig. 3 pipes are fixed on the absorbing plate by welding lead along the riser's pipes. was manufactured in fabricated work as curve surrounds riser pipes to increase the surface area of contacts between fig. 4. fig. 1 experimental test rig. khwarizmi engineering journal, vol. 11, no. 3, p.p. 3746 (2015) middle of the tested tube. the effects of twisted ratios (1, 2, 3, 4, 5and 6) are presented for reynolds number values ranging from re = 100 found that the heat transfer in the circular tube with the twisted tape is more ith no twisted tape inserted. ratio leads to decrease in the nusselt number and friction factor. the objective of the present work is to enhanced the performance of the flat plate solar collector by inserting twisted strips with ratios (tr=3, 4 and 5). the task was accomplished by connecting three configuration) parallel mode at experimental work experimental test rig the experimental test rigs consist of three identical flat plate solar collectors, each one with absorbing area (80cm * 120cm) with one glass 1. also, it consists of eight equally spaced (10cm) parallel copper riser pipes inner and 11mm outer) diameters, and (1200mm) length. these pipes are connected with two headers, one on each end. the joints between headers and copper pipes ends are made by adapter screws as shown in fig. 2. the main purpose of these adapter screws is for easy separating of riser pipes from the headers to inserting twisted strips inside them. a copper thickness is used as the solar as shown in fig. 3. the riser pipes are fixed on the absorbing plate by welding pipes. the absorbing plate fabricated way through the work as curve surrounds riser pipes to increase the contacts between them as shown in experimental test rig. jafar m. hassan fig. 2. joins header and riser piped end by adapter screw. fig. 3. copper sheet welding to the riser pipes fig. 4. absorbing plate geometry al-khwarizmi engineering journal, vol. 11, no. 3, p.p. 39 joins header and riser piped end by adapter copper sheet welding to the riser pipes. absorbing plate geometry. the collector frame is made of aluminum bars of (1.5mm) thick. a glass sheet is used as a transparent cover (4mm) thick glass wool insulation of (50 mm) thickness was used as insulator to decrease the collector back and side heat losses. a cylindrical galvanized steel tank with (0.58 m) outside diameter and (1 m) height is used for storing h insulated by a (50mm) thickness glass wool. in order to circulate the water in the system, a small circulation water pump (crs25/4 closed loop to make the forced circulation. the water flow rate in the closed loop is using valves and measured with flow meter 15-range (60-600lph) with accuracy 4% flow rates used, are (60,100 and 150) spray paint (rustoleum high heat) as the absorber surface paint is used high absorptance (0.92-0.96 used to substrates with low emittance (0.24) [ 2.2. measuring devices analyzing in order to measure the temperature at various points of the absorbing plate collectors, t-type thermocouple constantan) with the accuracy of [9]. the thermocouples were calibrated before beginning of the experiments. the measurement of the temperature distribution of the absorbing plate is done using three thermo located at the centerline of the absorbing plate and the others at top and bottom with space distance of (50cm) from the centerline as shown in all thermocouples are connected to the data logger, that’s connected to thermometer (ut325-0.1c resolution). the data is interfaced to the computer and then displayed as a table. the ambient temperature is measured using a digital electronic thermometer. the solar power radiation on the collector is record by solar meter with rang varied from 2000 w ̸m2). this device measures the total solar radiation (beam and diffuse) per unit area of the collector surface. the solar power meter was oriented due to the south at the collector tilt angle (30). this device can read the in (sd ram). khwarizmi engineering journal, vol. 11, no. 3, p.p. 3746 (2015) the collector frame is made of aluminum bars of (1.5mm) thick. a glass sheet is used as a thick of the collector. a glass wool insulation of (50 mm) thickness was decrease the collector back a cylindrical galvanized steel tank with (0.58 m) outside diameter and (1 m) height is used for storing hot water. the tank is insulated by a (50mm) thickness glass wool. in order to circulate the water in the system, a small (crs25/4-180) is used in closed loop to make the forced circulation. the water flow rate in the closed loop is controlled by using valves and measured with flow meter (lzs600lph) with accuracy 4%. the flow rates used, are (60,100 and 150) ℓ /hr. the spray paint (rustoleum high heat) as the is used. this coating has 0.96) for solar radiation is to substrates with low emittance (0.24) [8]. devices and data in order to measure the temperature at various points of the absorbing plate, inlet and outlet of thermocouple (copper with the accuracy of (±0.5 ͦc) is used ]. the thermocouples were calibrated before beginning of the experiments. the measurement of the temperature distribution of the absorbing plate is done using three thermocouples, one located at the centerline of the absorbing plate and the others at top and bottom with space distance of (50cm) from the centerline as shown in fig. 5. all thermocouples are connected to the data logger, that’s connected to a digital electronic 0.1c resolution). the data is interfaced to the computer and then . the ambient temperature is measured using a digital electronic thermometer. the solar power radiation on the collector is th rang varied from (0 to . this device measures the total solar radiation (beam and diffuse) per unit area of the collector surface. the solar power meter was oriented due to the south at the collector tilt angle (30). this device can read the data and save them jafar m. hassan fig. 5. position of thermocouples of absorber plate the governing equations used in the present work are: 1. water mass flow rate (�� �) �� � � �� . �� the water density varies with its temperature according to the equation [10] �� � 1000 ∗ �1 � �� � 288.9414� �t � 68.12963�� ∗ �� � 3.9863�� 2. useful energy (��) ���� !" � �� � . �#$��� !" . ��%&� � 3. the collector efficiency for individual solar collector ' �� !" � ()*+,-. /0 .12 4. the mean fluid temperature is calculate by �3 � 45678459), � 2.3. test model in this model, using twisted investigate the influence of heat enhancement devices on the thermal performance of the flat plate solar collector arrays. in this study, t twisted strips elements are made from thin, flat strips of thickness (0.7 mm) and (10.5mm) wide of aluminum material and are twisted through (180 degree) to form helices shapes. twisted in different ratios (tr=3,4,5) fig. 6 .helices rotations of this ratios are formed for a full length of riser pipes of (1100 mm ) as shown in fig. 7. in this model, three flat plate solar collectors connection in parallel (z configuration)as shown in fig.8 (collector one with twist ratio 3, collector two with twist ratio 4 and collector three with twist ratio 5) for different flow rates .the twist ratio is defined as: al-khwarizmi engineering journal, vol. 11, no. 3, p.p. 40 sition of thermocouples of absorber plate. the governing equations used in the present …(1) the water density varies with its temperature �/�508929.2 ∗ …(2) � �%<=� …(3) collector efficiency for individual solar …(4) uid temperature is calculate by ...(5) strip was to investigate the influence of heat enhancement devices on the thermal performance of the flat plate solar collector arrays. in this study, the strips elements are made from thin, flat strips of thickness (0.7 mm) and (10.5mm) wide material and are twisted through shapes. the strips are =3,4,5) as shown in .helices rotations of this ratios are formed for a full length of riser pipes of (1100 mm ) as three flat plate nnection in parallel (z (collector one with twist ratio 3, collector two with twist ratio 4 collector three with twist ratio 5) for different flow rates .the twist ratio is defined as: �> � ? @ the twist strip geometry as shown in 2.4. test procedure the forced circulation of solar flat plate collectors were connected as a closed loop. the experiment was carried out in baghdad from (15th april to 10th may 2014) and these experiments were carried out during sunny days only .the slope angle of three clos (30 deg. due to south). the collectors was tested under steady-state conditions in which the solar intensity, ambient temperature, inlet and outlet temperature difference were considered constant for period of time. the period was an hour for a clear day. the type of test was to estimate the instantaneous performance of the system. the system was tested with three different flow rates of water through the collector loop . these flow rates were (60,100 and 150) each case, experiments usually started at 8 am and continued until 5 pm .in each test and each time period all the measurements of temperatures, solar radiation intensity were recorded for each collector. each test was repeated twice at different periods of time to ensure the experimental repeatability. fig. 6. a twist strips with different twist ratio fig. 7. a twisted strip inside riser pipe. khwarizmi engineering journal, vol. 11, no. 3, p.p. 3746 (2015) ... (6) the twist strip geometry as shown in fig. 9. the forced circulation of solar flat plate collectors were connected as a closed loop. the experiment was carried out in baghdad from (15th april to 10th may 2014) and these experiments were carried out during sunny days only .the slope angle of three closed looped collectors in the collectors was tested state conditions in which the solar intensity, ambient temperature, inlet and outlet temperature difference were considered constant for period of time. the period was taken as half an hour for a clear day. the type of test was to estimate the instantaneous performance of the the system was tested with three different flow rates of water through the collector loop . (60,100 and 150)ℓ /hr. in each case, experiments usually started at 8 am and continued until 5 pm .in each test and each time period all the measurements of temperatures, solar radiation intensity were recorded for each each test was repeated twice at different of time to ensure the experimental with different twist ratios. twisted strip inside riser pipe. jafar m. hassan fig. 8. schematic diagram of test rig . fig. 9. twisted strip geometry 3. results and discussion 3.1. relationship between solar energy and useful energy fig 10. shows the useful energy have the same trends of the solar radiation. the results show that, when the water flow rate inlet to the collector increases, the useful energy gain increases. this affects due to, as the flow rate temperature rise through the collector decreases. this causes lower losses and therefore a corresponding increase in the gain al-khwarizmi engineering journal, vol. 11, no. 3, p.p. 41 schematic diagram of test rig . twisted strip geometry. between solar energy fig 10. shows the useful energy have the same trends of the solar radiation. the results show inlet to the collector increases, the useful energy gain increases. this increases, the temperature rise through the collector decreases. this causes lower losses and therefore a the gain of the useful energy. the value of useful with inserted strip of twist ratio 3 is the others for the same solar intensity. this effect results the intensity of swirl generation. as the twist ratio decrease, swirl generation which would maximize the particle mixing and hence the heat transfer coefficient. 3.2. the absorber plate temperature variation fig.11 shows, the temperature distribution of the absorber plate and ambient temperatures with time with different twist ratios. among the various twist ratios, the minimum twist ratio (3) is found to have the lowest absorber plate temperature for all flow rate effective of heat transfer by swirl and fin effects. as the twist ratio increase, the swirl generation and fin effect decreases and minimizes the heat transfer and increase the absorber plate temperature. table (1,2 and 3) shows the variatio of absorber plate temperature with time for the flow rate inlet at 150ℓ/hr. 3.3. effect of twist ratio on thermal performance analysis according to the flow rates range in the present work the instantaneous collector efficiencies curves are shown in 14) been observed clearly that as the flow rate increases, the efficiency of the solar collector also increases. the increase in the flow rate, leads to temperature difference decreases. the decreasing of the temperature difference lead to maximum energy transfer from the riser fluid, then the collector efficiency will increase. for the same values of the solar radiation maximum efficiency is obtained in minimum twist ratio (3), because the swirl generation is maximum in this twist ratio, which would increase the heat transfer of fluid travel. experimental daily efficiencies for the solar collector used strips with twist ratio (3) and flow rate of order 60,100 and 150 and 63% respectively. tables (4, the instantaneous collector efficiencies for different flow rates. khwarizmi engineering journal, vol. 11, no. 3, p.p. 3746 (2015) of useful energy of the collector with inserted strip of twist ratio 3 is higher than others for the same solar intensity. this effect results the intensity of swirl generation. as the , swirl generation increase, the particle mixing and hence the heat transfer coefficient. absorber plate temperature shows, the temperature distribution of the absorber plate and ambient temperatures with time with different twist ratios. among the various twist ratios, the minimum twist ratio (3) is found to have the lowest absorber plate for all flow rate ranges due to effective of heat transfer by swirl and fin effects. as the twist ratio increase, the swirl generation and fin effect decreases and minimizes the heat transfer and increase the absorber plate table (1,2 and 3) shows the variation of absorber plate temperature with time for the effect of twist ratio on thermal performance analysis according to the flow rates range in the present work the instantaneous collector efficiencies curves are shown in fig’s (12,13 and ) been observed clearly that as the flow rate increases, the efficiency of the solar collector also increases. the increase in the flow rate, leads to temperature difference decreases. the decreasing of the temperature difference lead to the maximum energy transfer from the riser tube to then the collector efficiency will increase. of the solar radiation the maximum efficiency is obtained in minimum twist ratio (3), because the swirl generation is s twist ratio, which would increase the heat transfer of fluid travel. the experimental daily efficiencies for the solar collector used strips with twist ratio (3) and flow rate of order 60,100 and 150 l /hr. are 49 %, 57% tables (4, 5 and 6) show instantaneous collector efficiencies with time jafar m. hassan al-khwarizmi engineering journal, vol. 11, no. 3, p.p. 3746 (2015) 42 table 1, absorber plate temperature at twist ratio (3). time tp1 tp2 tp3 8.00 am 30.8 32.9 37 8.30am 32.3 34 39.5 9.00am 36.6 39.5 43.5 9.30am 41.2 43.2 46 10.00am 44.6 48.3 52 10.30am 47.4 50.2 53.2 11.0am 51.2 52.9 56.3 11.30am 54.3 56.8 58.6 12 noon 57.4 60.9 63.4 12.30pm 61.8 64.3 67 1.00pm 64.7 68.4 70 1.30pm 66 68.8 70.5 2.00pm 67.7 70.5 72.4 2.30pm 68.3 70.4 71.5 3.00pm 66.3 68.5 70.7 3.30pm 64.2 66.5 68.7 4.00pm 62.1 65 67.3 4.30pm 60.2 64 65.2 5.00pm 58.5 61.5 63 table 2, absorber plate temperature at twist ratio (4). time tp1 tp2 tp3 8.00 am 31 33.5 38.4 8.30am 33 34.5 40.6 9.00am 37 40.6 43.5 9.30am 42.2 44.2 46.5 10.00am 45 49 52.6 10.30am 48.6 50.7 53.2 11.0am 52 54.3 57.1 11.30am 55.2 57.7 59.3 12 noon 58.5 61.5 64 12.30pm 62.8 65.2 67.7 1.00pm 65.5 69 70.5 1.30pm 67 69.1 70.4 2.00pm 68.1 71 72.4 2.30pm 69 71.4 72.2 3.00pm 67.4 69.3 71.2 3.30pm 65.3 67.5 69.5 4.00pm 62.1 65 67.3 4.30pm 60.2 64 65.2 5.00pm 58.5 61.5 63 table 3, absorber plate temperature at twist ratio (5). time tp1 tp2 tp3 8.00 am 31.7 34 39.9 8.30am 34 35.3 41 9.00am 38.2 41.2 44.5 9.30am 42.7 45.3 47.1 10.00am 45.5 49.7 53.2 10.30am 49.2 51.6 55.2 11.0am 52.9 55.1 58.6 11.30am 55.8 58.2 60 12 noon 59 61.8 64.5 12.30pm 63.5 65.8 68 1.00pm 66 69 70.7 1.30pm 67.4 69.3 71.7 2.00pm 68.5 71.5 72.9 2.30pm 69.6 71.9 72.7 3.00pm 68.3 69.5 71.5 3.30pm 66.8 68.5 70 4.00pm 65 66.5 68.5 4.30pm 63.7 65 67.3 5.00pm 61.5 63.5 65.7 table 4, instantaneous collector efficiencies with time at flow rate ( 60 ℓ/hr. ). time ƞi-tr3 ƞi-tr4 ƞi-tr5 8.00 am 0.533 0.5145 0.45 8.30am 0.544 0.47 0.44 9.00am 0.56 0.48 0.4333 9.30am 0.55 0.47 0.4287 10.00am 0.52 0.45 0.3792 10.30am 0.51 0.481 0.3712 11.0am 0.54 0.46 0.39 11.30am 0.58 0.47 0.38 12 noon 0.529 0.4658 0.38 12.30pm 0.471 0.4289 0.3788 1.00pm 0.453 0.4023 0.33 1.30pm 0.422 0.371 0.3116 2.00pm 0.445 0.3465 0.297 2.30pm 0.402 0.329 0.2747 3.00pm 0.37 0.284 0.2295 3.30pm 0.32 0.2633 0.2132 4.00pm 0.28 0.187 0.1408 4.30pm 0.221 0.089 0.044 5.00pm 0.08 0.054 0.02 table 5, instantaneous collector efficiencies with time at flow rate (100ℓ/hr.). time ƞi-tr3 ƞi-tr4 ƞi-tr5 8.00 am 0.7 0.6662 0.5921 8.30am 0.7017 0.6049 0.5565 9.00am 0.7234 0.6631 0.6028 9.30am 0.7177 0.6343 0.5508 10.00am 0.7287 0.6653 0.5703 10.30am 0.6715 0.6015 0.5316 11.0am 0.6419 0.5789 0.5034 11.30am 0.6291 0.5807 0.5202 12 noon 0.6352 0.5764 0.4705 12.30pm 0.5808 0.486 0.4386 1.00pm 0.5522 0.4673 0.4106 1.30pm 0.516 0.4354 0.3709 2.00pm 0.4981 0.395 0.3263 2.30pm 0.46 0.3745 0.32 3.00pm 0.42 0.3378 0.3378 3.30pm 0.3041 0.2211 0.1935 4.00pm 0.26 0.1659 0.1327 4.30pm 0.11 0.0787 0.0787 5.00pm 0.0921 0.0461 0.0461 jafar m. hassan al-khwarizmi engineering journal, vol. 11, no. 3, p.p. 3746 (2015) 43 table 6, instantaneous collector efficiencies with time at flow rate (150 ℓ/hr.). time ƞi-tr3 ƞi-tr4 ƞi-tr5 8.00 am 0.7776 0.73 0.6957 8.30am 0.7983 0.79 0.69 9.00am 0.7569 0.7569 0.72 9.30am 0.77 0.77 0.7 10.00am 0.78 0.73 0.65 10.30am 0.7587 0.7 0.6225 11.0am 0.7461 0.7088 0.6342 11.30am 0.7112 0.67 0.57 12 noon 0.7256 0.6 0.55 12.30pm 0.6352 0.58 0.52 1.00pm 0.6134 0.55 0.5 1.30pm 0.5681 0.5289 0.45 2.00pm 0.53 0.48 0.4 2.30pm 0.5066 0.46 0.37 3.00pm 0.47 0.39 0.2909 3.30pm 0.43 0.36 0.3 4.00pm 0.3475 0.28 0.15 4.30pm 0.2143 0.1 0.0536 5.00pm 0.0781 0.07 0.6957 fig. 10. relationship between useful energy and solar radiation for different twist ratio and flow rates in z-configuration. fig. 11 relationship between absorber plate and ambient temperatures during day hours at 150 ℓ////hr. 0 100 200 300 400 500 600 700 800 900 1000 1100 w a tt time z-configuration at 60 ℓ/hr. solar radation 0 100 200 300 400 500 600 700 800 900 1000 1100 w a tt time z-configuration at 100 ℓ/hr. solar radation 0 100 200 300 400 500 600 700 800 900 1000 1100 w a tt time z-configuration at 150 ℓ/hr. solar radation 20 26 32 38 44 50 56 62 68 74 80 t e m p e ra tu re ͦc time z-configuration at twist 3 tp1 tp2 tp3 ta 20 26 32 38 44 50 56 62 68 74 80 t e m p e ra tu re ͦc time z-configuration at twist ratio 4 tp1 tp2 tp3 ta 20 26 32 38 44 50 56 62 68 74 80 t e m p e ra tu re ͦc time z-configuration at twist ratio 5 tp1 tp2 tp3 ta jafar m. hassan al-khwarizmi engineering journal, vol. 11, no. 3, p.p. 3746 (2015) 44 fig. 12. performance test 60 ℓ/hr. at different twist ratios. fig. 13. performance test 100 ℓ/hr. at different twist ratios. fig. 14. performance test for 150 llll/hr. at different twist ratios. 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.6 0.65 0 0.015 0.03 0.045 0.06 0.075 0.09 0.105 0.12 0.135 in st a n ta n e o u s e ff ic ie n cy ƞ i tm-ta/gt z-configuration twist ratio 3 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.55 0 0.015 0.03 0.045 0.06 0.075 0.09 0.105 0.12 0.135in st a n ta n e o u s e ff ic ie n cy ƞ i tm-ta/gt z-configuration twist ratio 4 0 0.1 0.2 0.3 0.4 0.5 0 0.015 0.03 0.045 0.06 0.075 0.09 0.105 0.12 0.135 in st a n ta n e o u s e ff ic ie n cy ƞ i tm-ta/gt z-configuration twist 5 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.6 0.65 0.7 0.75 0.8 0 0.015 0.03 0.045 0.06 0.075 0.09 0.105 0.12 0.135 0.15 in st a n ta n e o u s e ff ic ie n cy ƞ i tm-ta/gt z-configuration twist ratio 3 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.6 0.65 0.7 0 0.015 0.03 0.045 0.06 0.075 0.09 0.105 0.12 0.135 0.15 in st a n ta n o u s e ff ic ie n cy ƞ i tm-ta/gt z-configuration twist ratio 4 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.6 0.65 0 0.0150.030.0450.060.0750.090.1050.120.1350.15 in st a n ta n e o u s e ff ic ie n cy ƞ i tm-ta/gt z-configuration twist ratio 5 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.6 0.65 0.7 0.75 0.8 0.85 0 0.0150.030.0450.060.0750.090.1050.120.1350.150.1650.18in st a n ta n e o u s e ff ic ie n cy ƞ i tm-ta/gt z-configuration twist ratio 3 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.6 0.65 0.7 0.75 0.8 0.85 0 0.0150.030.0450.060.0750.090.1050.120.1350.150.1650.18 in st a n ta n e o u s e ff ic ie n cy ƞ i tm-ta/gt z-configuration twist ratio 4 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.6 0.65 0.7 0.75 0.8 0 0.015 0.03 0.045 0.06 0.075 0.09 0.105 0.12 0.135 in st a n ta n e o u s e ff ic ie n cy ƞ i tm-ta/gt z-configuration twist ratio 5 jafar m. hassan al-khwarizmi engineering journal, vol. 11, no. 3, p.p. 3746 (2015) 45 4. conclusions from the present work, we can conclude that: • the collector with minimum twist ratio (3) is found to have the lowest absorber plate temperature for the same test condition. • according to the flow rate ranges, the instantaneous collector efficiencies increase with increasing the flow rate for all twist ratios. • the maximum efficiency is obtained in minimum twist ratio (3), for all flow rates range presented in this work • the swirl generation and amount of heat transfer inside riser's pipes increase whenever twist ratio decreases. nomenclature 5. references [1] rose j.w., briggs a., "performance comparison of some tube inserts", int., commun, heat mass transfer, vol. 29, p.4556, 2002. [2] watcharin n., smith e. and pongjet p., "effect of twisted-strip inserts on heat transfer in a tube, the 2nd joint international conference on sustainable energy and environment, a-030 ,p., 21-23 november 2006. [3] alireza h. and kamran s., "experimental study on the effect of heat transfer enhancement devices in flat-plate solar collectors", international journal of heat and mass transfer, vol. 52, no. 19, pp. 46504658, 2009. [4] nagarajan p., nitesh m. and rohit c., "experimental studies on heat transfer and friction factor characteristics of parabolic trough solar water heating system with and without twisted strips", proceedings of the 37th national & 4th international conference on fluid mechanics and fluid power, iit madras, chennai, india, december 16-18, 2010. [5] herrero martín r., garcía pinar a., pérez garcía j.," experimental heat transfer research in enhanced flat-plate solar collectors", world renewable energy congress, sweden, 8-13 may, 2011. [6] akeel a. and ameer a., "experimental investigations in circular tube to enhance turbulent heat transfer using various types of twisted tape inserts", eng. & tech. journal, vol.29, no.14, pp.2961-2973, 2011. [7] withada, j. and amnart b., "effect of twisted ratio on flow structure heat transfer and thermal improvement in a circular tube with single twisted tape", journal of mathematics and statistics 10 (1): 80-91, 2014. [8] rhett n. , "the water wall-a passive solar collection and thermal storage device for supplementary radiant heating", master thesis, university of nevada, las vegas, december 2013 . [9] www.thermocoupleinfo.com [10] sinem e., "assessment of impact of reservoirs contaminated bottom sediments on surface water quality by sediment water interaction model", master thesis, the graduate school of engineering and sciences, april 2011. ab collector area ( m2) #$�� !" specific heat capacity of water (kj/kg.k) fr collector heat removal factor c4 incident solar radiation (w/m2) �� � water mass flow rate (kg/s) �� water volume flow rate (m3/s) d strip pitch (mm) ���� !" useful energy(w) ta ambient temperature ºc �%<= fluid in temperature ºc �%&� fluid out temperature ºc �3 mean fluid temperature ºc tp absorber plate temperature ºc �> twist ratio e strip width (mm) �� water density kg / m3 ' �� !" collector efficiency ƞi instantaneous efficiency ر ��دي ��ن �� � ���� 3، ا ��د�11ا ��ارز�� ا ��� �� ا ����� ،2015( 3746( 46 ���� /.-�( اد,!ل *(ا)' ��&�%� $�# اداء ����!ت ا �!ء ا ����� ا � 0� ***���� �8زي ���� ** �67 �4!د $�5 ا ��3ر * 3�4( ���ي 1 ا,:*89& ا,7)56,60'&/ 234 ا,01/.& ا,+')*(')'&***،**،* email: jafarmehdi1951@yahoo.com * email: kaisygj@yahoo.com** email: mohammed2007msc@yahoo.com *** الخالصة دا]t ا(*2a&y67o9 z'f اg4*م w>اt، uv اq9 ?ors ا7o, &h'3f &@*p)lm n'3ga&lo*ءة 9:+8*ت ا,+*ء ا,<+3'& ا,+f &gh3/ون اc/اث a=''> @? ا,<) ,=>ض ) d'c)tr=3,4,5 وn9 &b6+:9 c8p ا,<>اuv ا,+a3) ?@ &lo7`9 &y67o& اs,67اء . 2a ا.7`/ام ^_^& 9:+8*ت gh39 &'3+w& ,=>ض ا,/را.&. ر@q ا,+*ء q+:9 t(, ا,+*ء q@ر z'f*)ا t[ا,67ازي . دا gob ا,+:+8*ت uf2 رa) t(w–z ( *1hy<8aوo, وف<h *13l))8wsة ا/w>,ارة *ع ا<c &53? و در+ u'g+,ا .( ا,67اء &a3) /0b tkc ارة<g,ل ا*m7)s 89/ل gobان ا &'o+8,ا nv*70,ا cgp٣(او .( و p,q, &:'7)67اء ,و,sا &a30 *13l) &'96',ءة ا*l(,4'+& ا c)*m .,? gob ا,67ا %63و% q+:+o,)60,100,150 (<7, / c=of &b*.49% ،57 ا,<+3? ,8/د n9 4'2 89/ل ا,:>y*ن (microsoft word \307\323\355\341 \314\343\355\34114-21) al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 14, no.2, june, (2018) p.p.14 21 optimization drilling parameters of aluminum alloy based on taguchi method aseel jameel haleel department of production engineering and metallurgy/ university of technology email: en.aseel@yahoo.com (received 5 june 2017; accepted 4 december 2017) https://doi.org/10.22153/kej.2018.12.001 abstract this paper focuses on the optimization of drilling parameters by utilizing “taguchi method” to obtain the minimum surface roughness. nine drilling experiments were performed on al 5050 alloy using high speed steel twist drills. three drilling parameters (feed rates, cutting speeds, and cutting tools) were used as control factors, and l9 (33) “orthogonal array” was specified for the experimental trials. signal to noise (s/n) ratio and “analysis of variance” (anova) were utilized to set the optimum control factors which minimized the surface roughness. the results were tested with the aid of statistical software package minitab-17. after the experimental trails, the tool diameter was found as the most important factor that has effect on the surface roughness. the optimal drilling factors that minimized the surface roughness are (20mm/min cutting speed, 0.2 mm/rev feed rate, and 10mm tool diameter). keywords: analysis of variance (anova), drilling operation, surface roughness, taguchi method. 1. introduction the significant aim in the modernistic industry is to produce the products with great quality and smallest cost in smallest time. drilling process is essential for manufacturing industries and excessively used in the automotive industries, aircraft, and aerospace. although the new metal cutting methods have improved in the manufacturing environment, traditionally drilling operation till now considered one of the most popular machining operations [1]. aluminum is utilized in many industries to produce various products and is important to the world economy. aluminum and aluminum alloys are very significant in different industries in which the durability, strength, and light weight are required. hole quality characteristics is very significant in different application, which involve the hole diameter accuracy and the hole surface finishing. hole quality mostly dependent on the drilling tools and the cutting parameters which is can be optimized by using different methods such as “taguchi” approach and regression models. taguchi approach considers a good tool to design a system with top quality and excessively used in engineering analysis [3], for this reason many researchers concentrated on determining the best surface roughness and roundness error. taso and hochen (2008) implemented the estimation and assessment of trust force and surface roughness in the composite material drilling operation utilizing “taguchi” method and “neural network”. the tested results proved that the spindle speed and feed rate the most affecting to the surface roughness, while the drill diameter and feed rate are the most affecting to the thrust force [4]. kurt et al.(2009) used the “taguchi” approach to optimize the cutting parameters of the hole diameter accuracy and surface finish in dry drilling operations [2]. kilickap (2010) inspected the effect of cutting parameters, such as surface roughness, point angle on burr height, cutting speed, and feed rate aseel jameel haleel al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 1421 (2018) 15 produced when drilling al 7075. taguchi “orthogonal array”l27, “signal-to-noise” ratio and “anova” was used to find the best drilling parameters of al7075 [5]. tosun (2011) considered different factors in drilling aluminum-silicon carbide particulate (al/sicp ) metal matrix composite such as drill type, feed rate, spindle speed, heat treatment and point angle of drill. two factors (feed rate and tool type) determined as the important factors that effect on hole surface roughness [6] çiçek et al. (2012) investigated the optimal control factors for the hole quality of drilling aisi 316austenitic stainless steel with m35 high speed steel (hss) twist drills by utilizing taguchi technique [3]. navanth and karthikeya sharma (2013) utilized “taguchi” approach to get the minimal surface roughness (ra). taguchi “orthogonal array” l18 used to perform the drilling tests. the feed rate, cutting tool, and spindle speed were considered as control factors [1]. kabakli et al. (2014) show an assessment of the geometric accuracies and roughness in drilling process using u-drills. surface roughness, perpendicularity and cylindricity used as a parameters for assessment the affecting of the feed rate, speed, hole diameter and depth. the execution characteristics were measured and taguchi method, “signal-to-noise” ratio and “anova” were used to analysis the effects of the controlled factors at various levels to identify the optimal drilling circumstance for u-drills [7]. 1.2 drilling process drilling is one of the machining process which are used for differ purposes. the basic purpose of drilling process is to drilling cylindrical holes in workpieces. the holes are cut out material with cutting tool, which is known as drill. the end cutting tool used for drilling the workpeice called twist drill which is provided with two cutting edges. the drill is fixed in rotating spindle and cab be feed towards the workpiece. the spindle speed and the feed rate can be changed according to the workpeice. figure (1) shows the two motion of twist drill [8]. fig. 1. twist drill motion [8] 1.3 the surface roughness surface roughness is considering one of the main characteristics in metal cutting. surface roughness result from drilling process impact on the mechanical properties such as creep life, corrosion resistance, fatigue behavior and so on. surface roughness expressed by the vertical variations of the actual surface from its typical form. if these variations are great, the surface is rough. if they are few the surfaces is smooth. surface roughness usually measured by a device in which the stylus moves across the surface, the stylus movement is magnified and the signal record. the result is mostly express as (ra) or average roughness [9]. 2. methodology taguchi approach traditional experimental design methods are difficult and sophisticated to use. when the process parameters increases, the numbers of implemented tests should be increased, so taguchi method used to solve this problem. in “taguchi method” a specific design of “orthogonal arrays” used to study the total parameter with only few numbers of experiments. then, the results converted in to “signal-tonoise”(s/n) ratio to measure the quality characteristics corrupted from the required values. in order to assess the optimal parameter, generally there are three categories of “signal-to-noise”(s ∕ n) ratios [3]: aseel jameel haleel al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 1421 (2018) 16 “smallerthe –better” the “signal -to –noise” ratio for “smaller -the better” is shown in equation (1). � � = −10 log �� � y�� ��� � …(1)  “higherthebetter” the “signal -to –noise” ratio for the “higher thebetter” is shown in equation (2). � � = −10 log � � � � �� � ��� …(2)  “nominalthebetter” the “signaltonoise” ratio for the “nominal thebetter” is shown in equation (3). � � = 10 log � ��� …(3) where: y average of observed data y observed n observations number s2y variances of y. in this study, the drilling parameters were determined by using taguchi experimental design method. taguchi “orthogonal arrays”, s/n ratio, and anova, used to analyze the impact of the drilling parameters on surface roughness [10]. 3. experimental details 3.1 workpiece materials one of the commercial aluminum alloys was chosen as the work piece material for the test sample. the dimension of work piece was (330mm x 80mm x 20mm). table (١) shows the chemical composition of the alloy. the diameters of the drill were (6 mm, 8 mm, and 10 mm) and the used cutting tool was high speed steel (hss) twist drill. table 1, chemical composition of (al) alloy grade 5050. 3.2 selection of control factors and orthogonal array” three factors were chosen for this experiment. there are cutting speed, feed rate and drill diameter with three levels as shown in table (2). table 2, experimental factors and levels in taguchi approach the first step is to choose the “orthogonal array”, the “orthogonal array”l9 (33) was chosen to get the best drilling parameters. table (3) shows taguchi l9 “orthogonal array” and table (4) shows the control factors using “orthogonal array”. table 3, taguchi l9 “orthogonal array” experiments number “ a b c 1 1 1 1 2 1 2 2 3 1 3 3 4 2 1 2 5 2 2 3 6 2 3 1 7 3 1 3 8 3 2 1 9 3 3 2 table 4, control factors using “orthogonal array” experimens number levels cutting speed(mm/min) feed rate(mm/rev) tool diameter (mm) 1 15 0.1 6 2 15 0.2 8 3 15 0.3 10 4 20 0.1 8 5 20 0.2 10 6 20 0.3 6 7 25 0.1 10 8 25 0.2 6 9 25 0.3 8 3.3 sample preparation in this paper, the drilling process was executed by using (cnc fanuc series oi-mb) which is shown in fig.2, besides that, (mahr / marsurf ps1) were used to measure the surface roughness which is shown in fig. 3. the measurement of roughness repeated (3 time) at various positions on the drilled surface. elements composition % al 96.7 mg 1.8 fe 0.8 si 0.4 mn 0.1 cu 0.2 factors level 1” level 2” level 3” a: cutting speed (m/min) 15 20 25 b: feed rate (mm/rev) 0.1 0.2 0.3 c: tool diameter (mm) 6 8 10 aseel jameel haleel al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 1421 (2018) 17 the average roughness parameters were selected as the output parameter to define the geometric irregularities of the surface drilled in different conditions. fig4 shows the twist hss drill with diameters (6, 8, and10) mm. fig. 5 shows the sample of the work piece with (9 through holes), fig. 2. cnc fanuc series oi-mb. fig. 3. surface roughness device (mahr / marsurf ps1). fig. 4. twist hss drill with diameters (6, 8, and 10) mm. fig. 5. the sample of the workpiece 3.4 analysis of “signal -to –noise” ratio taguchi approach used signal to noise (s/n) ratio to calculate the variance of the experimental design. the equation of (smaller-the-better) was chosen to calculate the (s/n) ratio, because the smallest value of surface roughness is required to get a good product quality. table (5) shows the result of surface roughness (ra) and (s/n) ratio of the surface roughness. table 5. the result of surface roughness (ra) and (s/n) ratio. experiments number levels surface roughness (ra µm) average (ra) s/n ratio cutting speed (mm/min) feed rate (mm/rev) tool diameter (mm) trail 1 trail 2 trail 3 1 15 0.1 6 0.275 0.375 0.439 0.363 8.801867 2 15 0.2 8 1.754 2.050 1.763 1.855667 -5.37 3 15 0.3 10 1.969 2.795 2.222 2.328667 -7.34215 4 20 0.1 8 1.159 1.713 1.159 1.343667 -2.56583 5 20 0.2 10 3.204 2.684 1.735 2.541 -8.10009 6 20 0.3 6 0.938 0.754 0.597 0.763 2.349509 7 25 0.1 10 2.755 2.686 3.450 2.963667 -9.43659 8 25 0.2 6 0.547 0.720 0.807 0.691333 3.20625 9 25 0.3 8 1.027 1.306 1.298 1.210333 -1.6581 ø6 mm ø10 mm ø8 mm m aseel jameel haleel al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 1421 (2018) 18 3.5 “analysis of variance” (anova) the “analysis of variance” (anova) is a powerful and common method of dividing total variation in to accountable sources of variation in an experiment. it is a statistical method used to explain the experimented data and make decisions about the parameters under study. in this research anova was utilized to analyze the effect of the cutting speed, feed rate, and the drill diameter on the surface roughness of the drilled holes. table (6) shows the formulas used to conduct the anova analysis. table 6, formulas used to conduct the anova analysis. df degrees of freedom �� �� !"# = # − 1 �� $##"# = %& − 1 r: number of factor levels nt: total number of observations ss sum of squares ss factor = ∑ %� . − /0��0 1 2 ss error = ∑ ∑ . − ��0��30 14� 2 yi : mean of observations at ith factor level y : mean of all observation yij : value of jth observation at ith factor level ms mean squares 56 �� !"# = 66 �� !"# �� �� !"# 56 $##"# = 66 $##"# �� $##"# f-value f value � = 56�� !"# 56 �� !"# p-value p coefficient p value indicates that the level has a significant effect. is a measure of how likely the sample result are, assuming the null hypothesis is true. p value range from (0 to 1). a commonly used of p value is 0.05 4. results and discussion minitab statistical software has been used to analysis of the experimental work. the equation of (the smaller-the-better) was chosen to calculate the (s/n) ratio of surface roughness, the response table for s/n ratio of (ra) shown in table (7) and the effect plots of the drilling parameters for signal to noise ratio was drawing using minitab17 as shown in figure (6). the plots show the response variations with the changes of drilling parameters, from figure (6) we can notice that in the increase of the drilling conditions (feed rate & cutting speed) the change in response will be change less than the change in the drilling condition (tool diameter) when we increase it. from the analysis the minimum value of (ra) achieves at drilling condition of cutting speed of (20 m/min), feed rate of (0.2mm/rev) and tool diameter of (10mm). then result of signal to noise ratio analyzed by using anova. in analysis of variance when the pvalue for the drilling factor less than (0.05) then this factor consider significant, and when the p-value greater than (0.05) then the factor consider insignificant. the result of anova of s/n ratio for (ra) shown in table (8). the optimal drilling condition shown in table (9) fig. 6. the effect plots for signal to noise ratio. aseel jameel haleel al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 1421 (2018) 19 table 7, response table for signal to noise ratios . level cutting speed(m/min) feed rate(mm/rev) tool diameter(mm) 1 -1.303 -1.067 4.786 2 -2.772 -3.421 -3.198 3 -2.629 -2.217 -8.293 delta 1.469 2.354 13.079 rank 3 2 1 table 8, the result of anova of s/n ratio for (ra). source df adj ss adj ms f-value p-value cutting speed(m/min) 2 3.936 1.968 0.18 0.849 feed rate(mm/rev) 2 8.316 4.158 0.38 0.726 tool diameter(mm) 2 260.756 130.378 11.83 0.048 error 2 22.045 11.022 total 8 295.053 where : df: degree of freedom adjss : sequential sum of squares adjms : mean sum of squares f-value : ftest p-value : p-coefficient table 9, optimal drilling condition. factors level value cutting speed(m/min) 5 20 feed rate(mm/rev) 5 0.2 tool diameter(mm) 5 10 5. conclusions in this study, the optimization of drilling parameters were executed by using taguchi approach to get the optimal surface roughness value in drilling aluminum alloy grade 5050 with hss twist drills. taguchi method, s/n ratio, and anova were successfully determining the optimal drilling conditions at level (5). from s/n ratio result based on ranking and anova result based on fvalue the tool diameter is the most significant control factor follow by feed rate and the cutting speed has the least significant on surface roughness. 6. references [1] navanth a., karthikeya sharma t.” a study of taguchi method based optimization of drilling parameter in dry drilling of al 2014 alloy low speeds” international journal of engineering sciences & emerging technologies, issn: 2231 – 6604 volume 6, issue 1, pp: 65-75 ,2013. [2] kurt m., bagci e., kaynak y., “application of taguchi methods in the optimization of cutting parameters for surface finish and hole diameter accuracy in dry drilling processes” , international journal of advanced manufacturing technology, vol. 40, no. 5-6, p. 458-469, 2009. [3] çiçek a. , kıvak t. ,and samta g. “application of taguchi method for surface roughness and roundness error in drilling of aisi 316 stainless steel”, strojniški vestnik journal of mechanical engineering 58: 3, 165174, 2012. [4] tsao c.c., hocheng h., “ evaluation of thrust force and surface roughness in drilling composite material using taguchi analysis and neural network” , journal of materials processing technology, vol. 203, no. 1-3, p. 342-348, 2008. [5] kilickap e., “modeling and optimization of burr height in drilling of al-7075 using taguchi method and response surface methodology”, the international journal of advanced manufacturing technology, volume 49, issue 9, pp 911–923, 2010. [6] tosun g., “statistical analysis of process parameters in drilling of al/sicp metal matrix composite”, the international journal of advanced manufacturing technology, volume 55, pp477–485, 2011. [7] kabakli e., bayramoðlu m., and geren n., “evaluation of the surface roughness and geometric accuracies in a drilling process aseel jameel haleel al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 1421 (2018) 20 using the taguchi analysis” , materials and technology 48 :1, 91–98, issn 1580-2949. 2014. [8] singh u.k., dwivedi manish , “manufacturing process” , new age international (p) ltd., publishers, second edition, 2009. [9] tamta n., jadoun r. s., “parametric optimization of drilling machining process for surface roughness on aluminum alloy 6082 using taguchi method” ,international journal of mechanical engineering (ssrgijme), volume2, issue7, 2015. [10] pradeep kumar j., packiaraj p. “ effect of drilling parameters on surface roughness, tool wear, material removal rate and hoe diameter error in drilling of ohns” , international journal of advanced engineering research and studies(ijaers), volume i/ issue iii, 2012. )2018( 14-21، صفحة 2د، العد14دالهندسية المجلجلة الخوارزمي م اسيل جميل هليل 21 امثلية عوامل عملية التثقيب لسبائك االلمنيوم باعتماد طريقة تاكوجي ليلـاسيل جميل ه هندسة االنتاج والمعادن/ الجامعة التكنولوجيةقسم en.aseel@yahoo.com :البريد االلكتروني الخالصة ثقوب) على عينة ٩) لغرض تقليل الخشونة السطحية. تم تثقيب ( taguchi methodالتركيز على امثلية عوامل التثقيب باستخدام (هذا البحث تم في تحكم (سرعات بوصفها عوامل. تم استخدام ثالث معامالت لعملية التثقيب من الصلب عالي السرعة باستخدام بريمة تثقيب٥٠٥٠من سبيكة االلمنيوم )s/n ratio" و (anovaاستخدمت طريقة "تحليل التباين الجراء التجارب.(l9) معدالت التغذية وعدد القطع) واختيار المصفوفة القطريةالقطع, العامل وجد ان قطر البريمة هو )mintab17لتحديد عوامل التثقيب المثلى التي تقلل من خشونة السطح. تم اختبار النتائج بمساعدة البرنامج االحصائي ( ملم/ دورة , قطر ٠٫٢ملم/دقيقة , معدل تغذية ٢٠على الخشونة السطحية والعوامل المثلى التي تم الحصول عليها القل خشونة هي (سرعة القطع اً االكثر تأثير ملم).١٠بريمة 7381 al-khwarizmi engineering journal,vol. 11, no. experimental study hydroforming muthanna h *,**,***department (received abstract lightweight materials is used in the sheet manufacturing of complex structural components into a single body with high structural stiffness. sheet hydroforming has been successfully developed in industry s the aim of this study is to simulate hydroforming process, stresses, and strains distribution) with for aluminum alloy (aa5652) sheets with (aht) respectively in the circular die approaches show the same tendency that an improvement formability aht for same metal. keyword : sheet hydroforming , stress and strain distribution, aluminum alloy, forming limit diagram. 1. introduction hydroforming is a forming technology for tube and sheet material aiming at high part strength and the manufacturing of complex geometries in one process step. even straining of the material caused by the fluid pressure leads to a uniform deformation in the sheet, which improves the dent resistance of the hydroforming part compared with conventional stamped parts and the uniform rise in yield strength in the used materials resulting in lower necessary wall thicknesses lightweight materials, in particular, aluminum alloys have been widely used in automotiv aircraft industry as the high strength ratio of aluminum results in significant weight and fuel savings [2–3]. in addition to weight reduction, utilization of aluminum offers some other advantages such as better corrosion resistance, higher recyclability potential and khwarizmi engineering journal,vol. 11, no. 4, p.p. 7381 (2015) study and numerical simulation ydroforming process for aluminum alloy aa5652 hamza sadoon* sadiq jaffar aziz hiba abdali jassim*** department of mechanical engineering / university of technology *e-mail: dr.muthanna@yahoo.com **e-mail: zaqsam@hotmail.com ***e-mail: hibaabdali@yahoo.com (received 31 march 2014 ; accepted 16 june 2015) in the sheet metal hydroforming process, because it can be adapted to the manufacturing of complex structural components into a single body with high structural stiffness. sheet hydroforming has been successfully developed in industry such as in the manufacturing of the components of automotive simulate the experimental results ( such as the amount of pressure required to , and strains distribution) with results of finite element analyses (fea with thickness (1.2mm) before heat treatment (bht) circular die with cavity equals to (20mm) . the comparison of results by these two approaches show the same tendency that an improvement formability, also the plastic deformation is greatly enhanced sheet hydroforming , stress and strain distribution, aluminum alloy, forming limit diagram. hydroforming is a forming technology for tube material aiming at high part strength and the manufacturing of complex geometries in one process step. even straining of the material caused by the fluid pressure leads to a uniform , which improves the dent forming part compared with conventional stamped parts and the uniform rise in yield strength in the used materials resulting in lower necessary wall thicknesses [1] . lightweight materials, in particular, aluminum alloys have been widely used in automotive and aircraft industry as the high strength-to-weight ratio of aluminum results in significant weight and . in addition to weight reduction, utilization of aluminum offers some other advantages such as better corrosion recyclability potential and increased energy absorption during a crash situation. 5xxx alloys, in particular, have the highest formability, and are used in automotive inner panels[4]. automotive industry has a special interest in aa5754 because of its hig lightweight, strength and weldability properties [5]. however, because of their susceptibility to microstructural damage, aluminum alloy sheets generally exhibits a lower level of formability compared to typical sheet steels utilization of aluminum alloys in the automotive industry has been far behind of steel because of cost and formability issues at room temperature [7]. in this study, the sheet materials of al (aa5652 t = 1.2mm) was annealed by heavy electric furnace. the annealing temperatures considered for aluminum materials were 345°c. the holding time in the furnace was (1) hour and then cooled in the furnace. the specifications of al-khwarizmi engineering journal (2015) of sheet aa5652 sadiq jaffar aziz** nology because it can be adapted to the manufacturing of complex structural components into a single body with high structural stiffness. sheet hydroforming uch as in the manufacturing of the components of automotive. the experimental results ( such as the amount of pressure required to nt analyses (fea) (ansys 11) heat treatment (bht) and after heat treatment the comparison of results by these two the plastic deformation is greatly enhanced sheet hydroforming , stress and strain distribution, aluminum alloy, forming limit diagram. increased energy absorption during a crash 5xxx alloys, in particular, have the highest formability, and are used in automotive inner . automotive industry has a special interest in aa5754 because of its high ductility, lightweight, strength and weldability properties however, because of their susceptibility to microstructural damage, aluminum alloy sheets generally exhibits a lower level of formability compared to typical sheet steels [6]. furthermore, utilization of aluminum alloys in the automotive industry has been far behind of steel because of cost and formability issues at room temperature in this study, the sheet materials of aluminum was annealed by heavy-duty electric furnace. the annealing temperatures considered for aluminum materials were 345°c. the holding time in the furnace was (1) hour and then cooled in the furnace. the specifications of muthanna hamza sadoon furnace include maximum temperature 1000°c, 6.5 kw and 220 v to improve the softer metal and reduce internal stresses in addition to the change in the internal structure of the alloy homogeneity, making it more than it was before the fermentation process. table 1, chemical composition of aa5652. material element %si aa5652 nominal composition 0.4 max. actual composition 0.095 2.2 uniaxial tensile test the uniaxial tensile test is the basis for defining mechanical properties of materials. it is standardized in astm standard e8m specification. the specimens were tested along the three directions, with the tensile axis being fig. 1. tensile specimen table 2, shows the mechanical properties of aa 5652 material young's modulus, e (gpa) aa5652 t = 1.2 mm bht 70 aht al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 74 furnace include maximum temperature 1000°c, improve the softer metal and reduce internal stresses in addition to the change in the internal structure of the alloy homogeneity, making it more than it was before the 2. experimental procedure 2.1 chemical composition the chemical compositions of sheet material were found out by spectrometry and are reported in table (1). %fe %cu %mn %mg %zn 0.4 max. 0.04 max. 0.01 max. 2.2-2.8 0.1 max. 0.197 0.002 0.013 2.33 0.018 the uniaxial tensile test is the basis for defining mechanical properties of materials. it is in astm standard e8m specification. the specimens were tested along the three directions, with the tensile axis being parallel (0o), diagonal (45 (90o) to the rolling direction (1) for specimens with round or rectangular cross sections. table (2), illustrate properties of aa 5652 from tensile test after heat treatment respectively ensile specimen bht and aht( all dimension in mm). of aa 5652 from tensile test before heat treatment. young's modulus, e (gpa) strain hardening index n hardening coefficient k (mpa) 0.4 650 0.36 575 khwarizmi engineering journal, vol. 11, no. 4, p.p. 7381 (2015) experimental procedure chemical composition compositions of sheet material spectrometry and are reported %cr %al 0.15-0.35 rem. 0.280 97 ), diagonal (45o), and perpendicular ) to the rolling direction as showed in figure for specimens with round or rectangular cross illustrate the mechanical from tensile test before and after heat treatment respectively . . anisotropy factor r 0.77 1 muthanna hamza sadoon al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 7381 (2015) 75 2.3 hydroforming sheet to find out the amount of applied pressure required for the hydroforming process and study the changes in stresses and strain generated in the sheet of aluminum aa5652 (t = 1.2mm) before and after annealing process. hydroforming die consisting of two parts as show in figure (2), upper and lower die. the depth of the lower die is (20mm) which was representing die cavity. while the upper die was represent chamber of oil. blank holder force was 200n to prevent leakage between upper and lower die also to connect the sheet with lower die. figure (3) shows the specimen shape before and after hydroforming process. (a) (b) fig. 2. hydroforming die (a) lower die (b)upper die. fig. 3. the specimen before and after hydroforming process. 2.4 pressure and depth measurement a digital camera type sony, model dsc w670, 16.1 mega pixels was used to record during the hydroforming process. the final results of applied pressure and forming depth can be obtained from the saved movie. in this work, gage pressure device is 600 bars used, the depth during the hydroforming process can be measured by a dial-gauge device. it is attached to the die by an adjective pin of (ф 3-0.006 mm) in diameter which is located in a deep drilled hole in lower half of die to be attached to the lower side of the aluminum sheet, the accuracy of dial-gauge is 0.01mm. 2.5 forming limit diagram fld represents the locus of the necked or fractured position of sheet metals in the space of in-plane principal strains, where ε1 is the major strain and ε2 is the minor strain. fld was calculated to aa5652 bht & aht as shown in fingers ( 4) & (5) to know formability of sheet metal also investigate the maximum strains can be endured without fractured . in order to be able to determine the local deformation of the formed sheet, line patterns with defined geometries (grids) are marked on the sheet specimens prior to forming. the subsequent forming process causes the line patterns to deform by an amount which depends on the local deformation experienced by the sheet part. fig . 4. forming limit diagram bht. fig . 5. forming limit diagram aht. ∈� % ∈� % ∈� % ∈� % muthanna hamza sadoon al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 7381 (2015) 76 3. finite element software package ansys11 ansys is a commercial, finite element analysis, software package with capability to analyze a wide range of different problems [8]. for simulating the sheet hydroforming in a circle die processes, commercial fea software ansys11 was used, in which the "newton-raphson" implicit approach was employed to solve nonlinear problem. in this approach, the stroke steps on outer surface of blank were defined explicitly over a time span. within each step, several solutions (substepes or time steps) were performed to apply the pressure gradually. at each substep, a number of equilibrium iterations were performed to obtain a converged solution. before each solution, the newton-raphson method evaluated the out-ofbalance load vector, which was the difference between the restoring forces (the loads corresponding to the element stresses) and the applied loads. the 3-d 8-node structural solid element of solid95 was used for workpiece (blank).the tool set (die and blank holder) was modeled as rigid bodies. fluid pressure was defined using a pilot node; this node was also employed to obtain the drawing force during the simulation. 4. effective stress & strain functions the work done in deforming the unit element is [9]: ��� . = ���� + ���� + ���� … (1) for a plane stress process, this becomes [9]: �� . = � ���� +� ��� � ��� … (2)�� � the plastic work done on a unit volume of material deformed in the tensile test to a true strain of ε1 (where σ2 = σ3 = 0) will be, from equation (2). �� . = � ��� . = � ��� � ��� … (3)�� � i.e. the work done per unit volume is equal to the area under the true stress–strain curve. the plastic work done per unit volume in an increment in a process is given by equation (1). it would useful if this could be expressed in the form ��� . = ��( �, �, �)���(��, ��, ��) … (4) as the element is yielding during deformation, a suitable stress function to choose is that given by the von mises yielding criterion, which has already been shown to have the value of the flow stress. for plane stress this function is: [9] ��( �, �, �) = �√1 − " + "�# � … (5) this function is called the representative, effective or equivalent stress, , and if the material is yielding, it will be equal to the flow stress. for a general state of stress in an isotropic material the effective stress function is: % = &12 '( � − �)� + ( � − �)� + ( � − �)�( … (6) in plane stress, the effective stress function is: % = * �� − � � + �� = +,1 − " + "�� … (7) as indicated, if the material element is at yield, this function will have the magnitude of the flow stress, σf. the required strain function in equation (4) can be found by substitution of the stress function. this function is known as the representative, effective or equivalent strain increment dε and for plane stress, the function is: ��%%% = ���(��, ��, ��) =*/� '1 + 0 + 0�( ��� … (8) in a general state of stress it can be written as [9] ��%%% = &23 '���� + ���� + ����( = &29 '(��� − ���)� + (��� − ���)� + (��� − ���)�( … (9) in a monotonic, proportional process, equations (8) and (9) can be written in the integrated form with the natural or true strains ε substituted for the incremental strains dε; i.e. [9] �̅ = &43 '1 + 0 + 0�( �� … (10) �̅ = &23 '��� + ��� + ���( … (11) �̅ = &29 '(�� − ��)� + (�� − ��)� + (�� − ��)�( … (12) where, �,̅ is the representative, effective, or equivalent strain and it can be written in general form as the following5106. muthanna hamza sadoon �̅ = 7 + 1√27 � 1&1 � 27√7 � 10 � 0� where, r represents an average normal anisotropy. the equation (14 ) is used to calculate the equivalent stresses [9] ϭ9 � :�∈9�; 5. results and discussion figure (6) shows the relationship between internal pressure and depth of aa5652 sheet before heat treatment at each load step. in this test the difference between the total internal pressure to form the sheet in both experiments is 4% .the total pressure is 120 bar in experimental test and 125 bar for simulation test. the maximum depth was (18 mm) in experimental test and (17.7mm) in simulation test. fig. 6. relationship between internal pressure and sheet depth (bht). 0 20 40 60 80 100 120 140 0 5 10 p re ss u re ( b a r ) depth (mm) simulation experimental al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 77 … �13� an average normal the equation (14 ) is used to calculate the …( 14 ) shows the relationship between internal pressure and depth of aa5652 sheet before heat treatment at each load step. in this test the difference between the total internal pressure experiments is 4% .the total pressure is 120 bar in experimental test and the maximum depth was (18 mm) in experimental test and (17.7mm) relationship between internal pressure and while figure (7) illustrates the maximum depth is (19.8 mm) in experimental test and (19.4 mm) in simulation test of aa5652 sheet after heat treatment under applied pressure equals to that used in before heat treatment. also, these figures illustrate the effect of heat treatment works cause rearrange the crystals of the metal and increases the formability of the metal for hydroforming which makes the depth of product aht larger than the depth bht with same pressure. fig. 7. relationship between internal pressure and sheet depth (aht). observed approach practical results as (3 ) and (4) with the results of the simulation program as shown in figure calculating the highest stresses and strains is exposed as a result of the metal hydroforming process before and after heat treatment . also shows the effect of heat treatment on the behavior of the metal during the hydroforming process, giving more ductility due to re the metal and lower resistance to the stresses to which it is faced.∈�,∈�, 15 20 simulation experimental 0 20 40 60 80 100 120 140 0 5 10 p re ss u re ( b a r ) depth (mm) khwarizmi engineering journal, vol. 11, no. 4, p.p. 7381 (2015) ) illustrates the maximum depth is (19.8 mm) in experimental test and (19.4 mm) in simulation test of aa5652 sheet after heat under applied pressure equals to that used in before heat treatment. also, these figures illustrate the effect of heat treatment works cause rearrange the crystals of the metal and increases the formability of the metal for hydroforming epth of product aht larger than the depth bht with same pressure. relationship between internal pressure and observed approach practical results as tables (3 ) and (4) with the results of the simulation figures (8) and (9) for calculating the highest stresses and strains is exposed as a result of the metal hydroforming process before and after heat treatment . also heat treatment on the behavior of the metal during the hydroforming process, giving more ductility due to re-crystallization of the metal and lower resistance to the stresses to ,∈�calculated from the 10 15 20 25 depth (mm) simulation expermental muthanna hamza sadoon al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 7381 (2015) 78 grids on the cups , also �,̅ 9calculated by equations (13) and (14) .the observed results are in agreement with the finding of ref. [ 11] . the reference used tube hydroforming processes of aa6060 while the current study fouced on sheet hydroforming of aa5652. table 3, experimental results of the final stage of half aa5652 (t =1.2mm) sheet bht in a bulge region only. table 4, experimental results of the final stage of half aa5652 (t =1.2mm) sheet aht in a bulge region only. (a) (b) fig. 8. relationship between internal pressure and equivalent stress of aa5652 (t =1.2 mm) sheet (a) bht ( b ) aht. 0 100 200 300 400 500 600 0 25 50 75 100 125 150 e q u iv e la n t st re ss ( m p a ) pressure (bar) before heat treat ment after heat treatment pressure grid mm є1 є2 є3 <% =9 120 bar 0 0.3987 0.13914 -0.53784 0.5286 503 5 0.2613 0.09910 -0.3604 0.3521418 428 10 0.15651 -0.07823 -0.08028 0.156689 310 15 0.14188 -0.07323 -0.06865 0.14238 298 20 0.12321 -0.06823 -0.05498 0.124212 282 25 0.1159 -0.06011 -0.05579 0.116338 274 30 0.0965 -0.02356 -0.07294 0.0985923 257 pressure grid mm є1 є2 є3 <% =9 120 bar 0 0.5115 0.2201 -0.7316 0.75069 518 5 0.3286 0.20449 -0.5331 0.53837 460 10 0.2931 0.1294 -0.4225 0.43289 425.3 15 0.2731 -0.1194 -0.1537 0.27381 361 20 0.253892 -0.083 -0.17089 0.2589 359.72 25 0.20054 -0.1205 -0.0800 0.20189 323.23 30 0.17800 -0.096 0.0817 0.17820 309 muthanna hamza sadoon al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 7381 (2015) 79 (a) (b) fig. 9. relationship between internal pressure and equivalent strain of aa5652 (t = 1.2 mm) sheet (a) bht (b) aht. 6. conclusions 1. improving the elongation properties of the metal after heat treatment of the annealing process . 2. upper value of equivalent stress and equivalent strain bht were 503 and 0.5286 respectively while aht become the equivalent stress and equivalent strain 518 mpa and 0.75069 . 3. the hardness increasing after hydroforming process because the work hardening that occur during the process . 4. the pressure required of hydroforming process was lowered aht, because the characterization of the formability of metal improved . notation σ1, σ2 , σ3 principal stresses (mpa) ��, ��,�� principal strains ----- % effective stress (mpa) ̅ � ̅ effective strain ----- α stress ratio β strain ratio l specimen length mm w specimen length mm dl change in length mm dw change in width mm dt change in thickness mm 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0 25 50 75 100 125 150 e q u iv a le n t st ra in pressure (bar) before heat treatment after heat treatment muthanna hamza sadoon al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 7381 (2015) 80 7. references [1] s. novotny, m. geiger, “process design for hydroforming of lightweight metal sheets at elevated temperatures”, journal of materials processing technology 138, p.p594–599، (2003). [2] verbrugge m, lee t, krajewski pe, sachdev a, bjelkengren c, roth r, et al. mass decompounding and vehicle lightweighting. mater sci forum 2009;618– 619:411–8. [3] montalbo t, lee tm, roth r, kirchain r. modeling costs and fuel economy benefits of light weighting vehicle closure panels. 200801-0370, sae international; 2008. [4] bolt pj, lamboo napm, rozier pjcm. feasibility of warm drawing of aluminum products. j mater proc technol 2001;115:118–21. [5] wowk dl. effect of prestrain on the strain rate sensitivity of aa5754 sheet. ph.d dissertation, queen’s university, canada; 2008. [6] hosford w, caddell r. metal forming. ptr prentice hall; 1993. [7] ayres ra. alloying aluminum with magnesium for ductility at warm temperatures (25–250 ºc). metal trans a 1979;10:849–54. [8] ansys9.0 manual. sasip, inc, (2004). [9] z.marciniak, j.l.duncan, and s.j.hu, "mechanics of the sheet metal forming". second edition, butterworth-heinemann (2002). [10] v. gylienė and v. ostaševičius, " study of hydroforming by implementing necking criterion in fem code" , issn 1392 1207. mechanika. nr.4(54) ,2005. [11] sami abbas hammood, "numerical and experimental analysis of tube hydroforming in a square cross-sectional die " , m.s .c thesis , university of technology, department of production and metallurgy engineering (2012). )efg ،81 -73 )2015> 4، ا:.-د11-89> ا:bcارز7? ا:<5-/=> ا:7892 4567 123ة /.-ون 81 � ا����رو���� ا������ ����� ا��را� ا� ��� وا� �د ������ة ���ا$��#�"م � �� �� aa5652 ' *+*#( )�'ه � �ون', -� ***ھ 2 , � ,�� .��1 **�0دق . *،**،*** hij <=k=lmk=2:7.> / ا:<5-/> اm9:ا<=nb:b5ko:ا *?lوpok:qا -rps:ا: dr.muthanna@yahoo.com **?lوpok:qا -rps:ا: zaqsam@hotmail.com hibaabdali@yahoo.com ***?lوpok:qا -rps:ا : ا�045 <=:mt <uvwuوا3-ة و <x=>u ة-y.2:ا z[m=>:5=\ اwo: ]:وذ _`mfw:ا z=kab <=82t ?c زنb:ا <f=fd دنm.7 e7-co/3 .اm9l eyy3 _`mfw:ا z=kab <=82tm .m97 ?cل ا:mlbk7 \=5wb ?c m2[ <tm5wت ا:m=iرات اوbfbر z=kao:ب :.82=> اb8f2:ا jkl:2=> ا[ z67 <=82.:ا m`mo5:ة اm[me7 bه ا:-را/> ھpھ q7 ان ا:<-ف ، m7mlpu m`mol \7 تqm.flqدات واm>nqا \rزbb 48t ا:boا:? c? ) ا:zsj)p=2co وu.ا:87m.2> ا:peارr> (mm 1.2)وk=s/aa5652 ]2iu> اb=52:qم :q7 _`mfw (ansys11 )ا:z=8eo ا:.-دي uy2t يp`دا v:mj)20 mm (. <yf52:د اmrازد ]:p[و z=kao:48 اt 8=> ا:2.-نumj q=ieb w=3 q7 <ycاbo7 elm[ ةm[me2:ا m7mlpu \7 <=82.:ا m`mo5:ا <lرmy7 p=2co:82=> اt -.u 28.-ن: <l-8:ا . 93112 al-khwarizmi engineering journal, vol. 11, no. 1, p.p. the effect of soil content, drilling parameters diameter on the vibration assessment in the mauwafak ali tawfik* *,**,*** department (received abstract this paper represents a study of the effect of the soil type, the drilling parameters and the drilling tool properties on the dynamic vibrational behavior of the drilling rig and its assessment in the drilling system. so first, an experimental drilling rig was designed and constructed to embrace the numer the experimental work included implementation of the drill according to the difference in the grains size, at different rotational spee (thrust force), in a way that allows establishing the charts that correlate the vibration acceleration, the rate of penetration (rop), and the power consumption curves with the depth of drilling. in addition to that the ansys workbench experimental results. and it was also used to model other numerical keywords: soil, vibration, and drilling rig 1. literature survey in 2000 tucker and wang were motivated by the need to understand the complex vibrational states experienced by the active components of a drilling assembly, in order to better control their potential [1]. in 2001 ashley et al. dealt with the application of the multi-axis vibration chassis (mvc) to measure vibrations in multiple axes and using the achieved data to provide the drilling team with the necessary means to cont proper parameters to minimize specific vibration effects [2]. in 2002 gui et al. studied the subject of instrumented borehole drilling and using the achieved data from the measured parameters as a tool in subsurface investigation [3]. et al. attempted to explain the complicated behavior of oil well drillstring motion when both torsional stick-slip and lateral whirl vibration are involved [4]. in 2004 hendriks had focused on the khwarizmi engineering journal, vol. 11, no. 1, p.p. 93112 (2015) the effect of soil content, drilling parameters and on the vibration assessment in the drilling rig mauwafak ali tawfik* wafa abd soud* rami safaa alwan*** department of mechanical engineering / university of technology e-mail: drmat19853@yahoo.com e-mail: wafaabd_92@yahoo.com e-mail: rami.safaa@yahoo.com (received 8 april 2014; accepted 15 december 2014) this paper represents a study of the effect of the soil type, the drilling parameters and the drilling tool properties on the dynamic vibrational behavior of the drilling rig and its assessment in the drilling system. so first, an experimental and constructed to embrace the numerical work. he experimental work included implementation of the drill-string in different types of soil with different properties according to the difference in the grains size, at different rotational speeds (rpm), and different weights on bit (wob) (thrust force), in a way that allows establishing the charts that correlate the vibration acceleration, the rate of penetration (rop), and the power consumption curves with the depth of drilling. that the ansys workbench (the 14.0 release) software was used to simulate and verify the t was also used to model other numerical cases with different drill bit diameters. il, vibration, and drilling rig. wang were motivated by the need to understand the complex vibrational states experienced by the active components of a better control their ashley et al. dealt with the axis vibration chassis multiple axes and to provide the drilling with the necessary means to control the mize specific vibration gui et al. studied the subject of instrumented borehole drilling and using the achieved data from the measured parameters as a in 2002 leine attempted to explain the complicated behavior of oil well drillstring motion when both slip and lateral whirl vibration are in 2004 hendriks had focused on the analysis of torsional vibrations, lateral vib and the interaction between those vibrations specific experimental drill string set 2005 mihajlovic had focused on the separate analysis of friction-induced vibration mechanical systems and lateral vibratio systems due to mass-unbalance piovan and sampio presented a continuous model to study, by means of finite element discretization, the coupling of extensional, flexural and torsion vibration on a drill string al. modeled the drill string as a cantilever euler bernoulli beam, and a tunable vibration absorber (tva), as a semi active controller, was designed to suppress the forced bending (transverse) vibration during the drilling process ritto analyzed nonlinear dynamics of the string which included uncertaint 2011 liao had studied the through combined experimental al-khwarizmi engineering journal (2015) drilling tool drilling rig wafa abd soud** university of technology this paper represents a study of the effect of the soil type, the drilling parameters and the drilling tool properties on the dynamic vibrational behavior of the drilling rig and its assessment in the drilling system. so first, an experimental string in different types of soil with different properties ds (rpm), and different weights on bit (wob) (thrust force), in a way that allows establishing the charts that correlate the vibration acceleration, the rate of software was used to simulate and verify the cases with different drill bit diameters. analysis of torsional vibrations, lateral vibrations and the interaction between those vibrations in specific experimental drill string set-up [5]. in mihajlovic had focused on the separate induced vibrations in flexible mechanical systems and lateral vibrations in rotor unbalance [6]. in 2006 sampio presented a continuous model to study, by means of finite element discretization, the coupling of extensional, flexural and torsional vibration on a drill string [7]. in 2009 moradi et led the drill string as a cantilever eulerbernoulli beam, and a tunable vibration absorber (tva), as a semi active controller, was designed to suppress the forced bending (transverse) ion during the drilling process [8]. in 2010 near dynamics of the drillstring which included uncertainty modeling [9]. in liao had studied the drill-string dynamics combined experimental, modeling and mauwafak a. tawfik al-khwarizmi engineering journal, vol. 11, no. 1, p.p.93112 (2015) 94 numerical effort [10]. in 2012 rajnauth had focused on reducing the torsional vibration as a result of monitoring and implementing corrective actions [11]. in 2013 richard duff proposed an improved physical laboratory model to explore dynamic behaviors associated with vibration, where the model included contact with the borehole wall allowing a range of stabilization geometries while removing bit-formation interaction effects [12]. from the previously published works and papers it was observed that many drilling vibration associated problems were taken into consideration throughout the past years. these problems included the following: • studying drill-string dynamics. • the effect of non-linearities. • the vibrational behavior states. • utilizing measured drilling parameters data as an investigation tool. • vibration analysis. • vibration monitoring and control systems. • bit and bearings design. • finding new ways to model and analyze vibration. so this work can be considered as a first step towards the connecting link in the previously mentioned topics chain. 2. aims of the work the main aims of this work were: 1. designing and constructing an experimental drilling rig. 2. studying the effect of different soil types on the drilling rig vibration assessment and the rate of penetration (rop). 3. studying the effect of drilling parameters (rotational speed & wob) on the vibration assessment and the (rop). 4. studying the effect of the drill-bit size (diameter) on the drilling rig vibration assessment. 3. the experimental drilling rig for the sake of the experimental work an experimental drilling rig was designed and construct as shown in figure (1), which also can be tuned easily to work as a field drilling rig thanks to its adjustable height due to its removable extension legs. fig. 1. the experimental drilling rig. the drilling rig basically consists of three main parts: • the drill-string (drilling core). • the electrical motor and the inverter. • the chassis (frame). (details of the experimental rig are shown in appendix (a)). the drill-string represents the mechanical part of the system, and in general its function is to receive and transmit the weight on bit wob (thrust force) and the rotational movement to the drill bit, so that the downhole drilling action by the drill bit can take place. the electrical motor and the inverter can be characterized as the electronic part of the experimental drilling rig system, and it's the one responsible of generating the rotational motion and the torque (drilling energy) and controlling them. the chassis is made of angle iron welded to iron legs. the legs can be extended by adding the extension legs, where the rig is designed in a way that allows us to work on two levels, the first level is for field drilling which can be achieved by abandoning the extension legs, while the second level is for experimental drilling (i.e. drilling in a mold or a container) which can be achieved by adding the extension legs. 4. instruments throughout the experimental work it was essential to measure and record the vibration acceleration, the power consumption, and the rate of penetration (rop), and in order to achieve that piezoelectric charge accelerometers (b&k 4370) were used to measure vibration acceleration which was connected to a charge amplifier (b&k 2635) which was in turn connected to an oscilloscope mauwafak a. tawfik al-khwarizmi engineering journal, vol. 11, no. 1, p.p.93112 (2015) 95 (ads 1022c) to present the output signal. (see appendix d) also an inverter (hyundai n100plus/015sf) was implemented to control the frequency of the electricity and in turn control the rotational speed of the motor. for measuring the rate of penetration (rop) a simple mechanism was used which is illustrated in fig. (2). it consists of a slide bush (part (a)) with an adjustable-length pin (part (b)), and as the drillstring proceeds forehead during the drilling process the pin will be pushed downward with it by the upper slide bush (part (c)), the pin is in turn pointed to a ruler (part (d)) to measure the depth. fig. 2. rate of penetration (rop) measuring mechanism. 5. soil samples analysis for the sake of the experimental work three different soil samples were selected, these samples were then taken to the soil laboratory to examine their texture by performing the following procedure: the first step was to dry each soil sample in the drying oven for (24 hours) to assure that the measured mass is of the soil only (i.e. purely soil without moisture), after that (500 gram) were taken from each sample and washed with water on the no. 200 sieve (75 µm opening size) to primarily separate each sample into coarse grains portion and fine grained one. later and after drying each portion for another (24 hours) and to be capable of finding out the grains size distribution of each sample a set of sieves was used for the coarse grained portion (grain size > 75 µm), and for the fine grained portion (grain size < 75 µm) the hydrometer analysis was used. 6. theory of the drillstring in general vibration whether it was free or forced vibration, whether harmonic, periodic or random, it is basically defined as the oscillatory movement of a body about its equilibrium position. hereby in this work the vibration in the experimental drilling rig is resulting from the borehole-drill bit interaction. where the nonhomogeneity of the soil results in variable drag forces on the drill-bit head, in addition to the contrastive friction forces between the conveyer and the borehole wall. 6.1. the drillstring model let us consider the drill-string as an initially straight slender rotating beam with a circular cross-section (r) and length (l) in the undeformed state. the beam is referred to an inertial cartesian system o:xyz fixed to the undeformed beam. another cartesian reference system o:xyz measures the deformation and displacements of the beam. in figure (3) it is possible to see that the system o:xyz is rotated with respect to the system o:xyz by means of a typical sequence of rotation angles as usual in rotor-dynamics. fig. 3. reference systems and rotation angels. 6.2. kinetic and strain energies the kinetic energy can be expressed in the following form [19]: � = 0.5� �� �� � + � � + � �� + ���� ′� + � ′�� � � + ���� �� + 2���� �� ′� ′� �� … �1� the simplified expression of the strain energy (h), which will be (hs), can be described in the following form [19]: �� = 0.5 !" �#� + "� ��##� + �##�� +� � $����#�% �� + 0.5 !$�� ��##�# − �′�′′���# +� � " ��#( + �#�#� + �′�#��% �� + 0.5 !"�� ��#�## −� � �##�# + ��#�′���# + 3"��#��##� + �##��% �� …(2) mauwafak a. tawfik al-khwarizmi engineering journal, vol. 11, no. 1, p.p.93112 (2015) 96 the beam is subjected to its own weight, and the external work done by a vertical force due to gravity field can be expressed as [20]: * = ��+ �� ��� � …(3) 6.3. the numerical analysis in order to complete the requirements of the numerical analysis which are the drill-string geometry, the boundary conditions including the supports stiffness values (foundation stiffness* (, -(⁄ )), and the loads, the following route was taken which starts with using the autocad 2009 software to achieve the geometry. then to calculate the supports stiffness values, beam deflection formula was used, and the detailed calculations are as follows: 1) the values of the supports reaction forces were calculated as shown in figure (4) by adapting beam deflection formula: /0 = 1234 �5 + 2� 6"�05 27� /� = 8�3� 6"�5 �5� − �� − 3�� fig. 4. the drill-string free-body-diagram. f = obstruction and friction forces to the bit inserts and bit head surface respectively. (n) r = supports reactions. (n) y = supports deflection. (m) e = young’s modulus. (pa) i = area moment on inertia. (m4) since the summation of deflection at the supports location is equal to zero, so the value of �8�� can be found (assuming rigid supports). then by taking the summation of moment about (a), then the summation of forces, the values of �80� 27� �8(� will be obtained respectively. 2) the accelerometers were then attached to the location of the supports, each one at a time, so that the displacement of each support can be found and in turn its stiffness value (k). and finally comes the loads which were calculated as follow; at the beginning the power consumption curves for the experimental cases that have been achieved and for the free-run (idle run) (i.e. drilling with no contact between the drilling tool and the soil) were established, where the difference between the average values for the steady-state portion of them represents the drilling power consumption. and thus the loads were calculated as follows: 9:�;< �9� = =:<>�; �=� ∗ 7+�@2< �;@:4ab/ �c� …(4) 9 = 9:�;<deffghij − 9:�;<kieljm kelnnljm …(a) c = 2o�,� 60⁄ …(b) and according to the previous equations the only unknown value is that of �=� and by calculating it, the value of �1� for the experimental cases will be found as follows: ∑= = ∑1 ∗ < qlrgsj�fer� …(c) boundary conditions • at the supports position, radial deflection is constrained while axial translation about the drill string axis is permitted. • the drill-bit, the drill-string and the bearings are made of elastic homogeneous isotropic steel. • the soil stiffness is so small compared to the supports, and thus it was replaced by very low stiffness spring. finally and after having all the analysis requirements (geometry, boundary conditions and loads) the simulation of the original drill bit model size was available to verify the experimental results, where figure (5 and 6) shows the undeformed and deformed model of the drillstring. fig. 5. ansys undeformed model * foundation stiffness is the stiffness per the supports projected area the drill bit the supports (ballbearings) the drilling shaft the conveyer mauwafak a. tawfik al-khwarizmi engineering journal, vol. 11, no. 1, p.p.93112 (2015) 97 fig. 6. ansys deformed model. 6.3.1. the drill-string natural frequencies since the drilling parameters, including the drill-string rotational speed, effect on the vibration assessment had been studied in this work, so the ansys workbench were used to find the drillstring natural frequencies, to make sure that the implemented operating rotational speeds that had been chosen in the experimental work are away from the natural frequencies, and in turn the achieved results are away from the effect of resonance. the results for the drill-string natural frequencies that were obtained from the ansys workbench are as shown in table (1) below: table 1, the drill-string natural frequencies. depth (cm) the natural frequencies (r.p.m.) 1st 2nd 3rd 4th 0 0.06 9 10 310 2 0.07 9.04 10.63 310.61 4 0.07 9.12 10.22 330.32 6 9.03 10.75 313.25 --- 8 9.05 10.66 314.21 --- 10 9.07 10.67 311.42 --- 12 0.07 9.37 11.35 326.21 14 0.06 9.48 11.84 333.21 16 9.32 10.64 11.24 315.87 18 9.47 10.85 13.45 329.47 20 10.1 13.9 323.2 --- 22 0.05 9.37 10.35 318.18 24 0.03 9.47 10.78 332.21 26 9.64 10.78 13.25 331.77 28 0.08 9.34 11.87 321.42 30 9.26 10.81 319.47 --- 32 9.42 10.63 320.54 --- 34 0.05 9.21 13.98 310.25 36 0.08 9.54 10.27 324.27 38 9.32 10.88 314.87 --- 40 0.02 9.84 11.05 325.09 6.3.2. the drill-bit diameter effect additionally, the ansys workbench software was used to model other numerical cases with different drill-bit size (diameter) which are �∓ 25%� of the original drill bit model geometry size (diameter) to verify the effect of the drill bit size (diameter) on the vibration assessment and the results are as shown in figure (7) below: fig. 7. acceleration curves for different diameters. it was observed that for the same conditions (soil type, rotational speed and weight on bit) the smaller the drill bit is, the higher the vibration acceleration levels will be, and this may be attributed either to difference in mass and in turn the difference in inertia, the fact that the larger model mass works on dissipating the transferred vibrations more than the smaller model does or other dynamical behaviors where this point needs more investigation (provided that the drill-string rotational speed is away from resonance zones). 7. results and discussion for the sake of the experimental work the following parameters were chosen: three different samples of soil with different grain sizes, four different rotational speeds (50 – 100 – 150 – 200) rpm so that the rotational speed increases by folds and three weights on bit (wob/thrust force) with (50%) increment steps as follows (80 – 120 – 160) n. in addition to that and by using the ansys software it was available to simulate the original drill bit for the experimental cases that were accomplished for the purposes of verification, and further more the ansys software was used to model other theoretical cases with different drill bit model sizes (diameters) which are �± 25%� of the original drill bit model size (diameter). mauwafak a. tawfik al-khwarizmi engineering journal, vol. 11, no. 1, p.p.93112 (2015) 98 7.1. soil samples grains size distribution when it comes to vibration assessment and its severity, it turns out that they are clearly affected by the grains size distribution of the soil and the consistency of that distribution. figure (8) below shows the grains size distribution curves of the soil samples, where x-axis represents the grains size, and y-axis represents the percentage of the grains. fig. 8. grains size distribution curves. 7.2. the experimental results after finishing the soil samples analysis and the establishment of the grains size distribution curves, it was commenced with the experiments, and down hereby the obtained results, for each soil sample, are presented as follows: 7.2.1. silty-clay for first soil sample (silty-clay), the average values of the vibration acceleration levels (m/s2) from figure (9, 12, and 15) were as in table (1) in appendix (b). based on the revealed data, it can be said that vibration acceleration levels increase as the rotational speed increases. this can be attributed to the fact that external forces (that the soil exerts on the drill-bit whether they were obstruction forces to the rotation of the inserts or friction ones to the surface of the drill-bit head) which once were with little or no effect, now they do since �c� had increased. which eventually means that the time stepping of the forces exertion is now became less, and that is make the drill string exposed to the effect of more forces, and by that the drill string will be displaced more distance than before. that brings up the conclusion that the second reason for that increment in vibration acceleration is when the external forces shake the drill string out of its rotation axis center an imbalance force due to imbalance mass will be generated. according to imbalance force law it appears that �c� is the factor of the biggest impact. so increasing �c� will greatly increase the centripetal forces and in turn the vibration levels as well (provided that the system is away from the critical rotational speeds). it can be noticed that vibration acceleration levels decrease as the (wob) increases due to the fact that the higher the (wob) is, the higher the friction between the drill bit and the soil. so in other words, there will be more power dissipation in overcoming friction rather than in vibration, and of course higher friction means more reduction in the rotational speed, which in turn means lower vibration acceleration (according to the relation that was first drawn between the vibration and the rotational speed). not only that but also more importantly is that increasing the (wob) will diminish the effect of the external forces on the drill bit since now they will have to shake larger mass than before. in general the vibration acceleration levels were neither too high nor too low. the most likely explanation for this behavior can be attributed to the following factors, which are the grains size distribution and the homogeneity of that distribution (i.e. the larger the grains size and the more non-homogeneity that the soil have, the higher the vibration acceleration levels that will be encountered in it). the vibration acceleration levels decrement increases as the (wob) and the rotational speed increase. this observations can be attributed to the fact that forces that became effective in disturbing the drill string and shaking it out of its rotation center, as the rotational speed increased (i.e. the load stepping time was reduced), are more liable to dissipation due to increment in the (wob). the average values of the rate of penetration (rop) (cm/sec) from figure (10, 13, and 16) were as in table (2) in appendix (b). in reference to table (5), it can be stated that higher rotational speed results in higher rates of penetration (rop), since more excavation of the soil will be done. the rate of penetration (rop) is seemed to be affected by the (wob) in the same way that it did by the rotational speed and the higher the (wob) is, the higher the (rop) will be, but that's not completely practical due to the fact that (rop) will keep increasing with the (wob) up to a certain point, namely the founder point. after that point increasing the (wob) will have adverse effect on the (rop), because the drill bit will have mauwafak a. tawfik al-khwarizmi engineering journal, vol. 11, no. 1, p.p.93112 (2015) 99 more difficulty in overcoming increased friction, in addition to the fact that excessive (wob) will force the inserts of the drill bit deeply in the formation in a way that they can't be moved properly. it is worthy to mention that the silty-clay soil has low rate of penetration. that's because the silty-clay soil grains were sticking to the drill bit inserts causing less efficient drilling and that if they don't even make the drill bit clog which agrees with what came in reference [3]. and again this can be attributed to the grains size, because of the fact that the soil grains are generally under the influence of two main kinds of forces which are the gravitational and the surface forces, and the factor that designate the dominant force is the ratio of the surface area to the volume, so that the dominant force for the fine-grained soil will be the surface force and vice versa. and that what makes the silty-clay soil grains sticky. the rate of penetration (rop) increment increases as the (wob) and the rotational speed increase. this observation is attributed to the fact that the (rop) is in general the resultant of two factors, which are the rotational speed stirring action and the (wob) piercing action. based on that no (rop) will be achieved, no matter how high is the rotational speed, without applying (wob) and vice versa. and by relying on these facts it can be concluded that increment in one of these two factors will have a positive influence on the other factor's effect on the (rop). another point to be mentioned is that the rate of penetration (rop), in general, decreases with depth. the rates of penetration (rop) decrement percentage with depth from figure (10, 13, and 16) were as in table (3) in appendix (b). and this decrement in (rop) is the result of the decrement in rotational speed, as a consequence of higher drag forces due to accumulative increment in compaction. finally, the average values of the power consumption (watt) from figure (11, 14, and 17) were as in table (4) in appendix (b). for the power consumption it should be reminded here that it corresponds to the actual rotational speed not the preset one since constant torque was used in this thesis. by examining the power consumption curves it can be seen that the power consumption increases as the rotational speed increases, with a decrement in that increment which might be physically ascribed to having higher inertia. fig. 9. acceleration with depth. fig. 10. rate of penetration with depth. fig. 11. power with depth. fig. 12. acceleration with depth. mauwafak a. tawfik al-khwarizmi engineering journal, vol. 11, no. 1, p.p.93112 (2015) 100 fig. 13. rate of penetration with depth. fig. 14. power with depth. fig. 15. acceleration with depth. fig. 16. rate of penetration with depth. fig. 17. power with depth. 7.2.2. sand for the second soil sample (sand), the average values of the vibration acceleration levels (m/s2) from figure (18, 21, and 24) were as in table (5) in appendix (b). based on the revealed data, it can be said that vibration acceleration levels increase as the rotational speed increases. it also can be noticed that the vibration acceleration levels decrease as the weight on bit (wob) increases. in general the vibration acceleration levels were higher than those encountered in silty-clay soil by (16.58%). vibration acceleration levels decrement increases as the (wob) and the rotational speed increase. all of the above mentioned observations can be attributed to the same factors that were mentioned in the silty-clay soil. the average values of the rate of penetration (rop) (cm/sec) from figure (19, 22, and 25) were as in table (6) in appendix (b). in reference to table (9), it can be stated that higher rotational speed means higher rates of penetration (rop). the rate of penetration (rop) is seemed to be affected by the (wob) in the same way that it did by the rotational speed and the higher the (wob) is, the higher the (rop) will be, but that's not completely practical due to the fact that (rop) will keep increasing with the (wob) up to a certain point, namely the founder point. after that point increasing the (wob) will has adverse effect on the (rop). it is worthy to mention that the sand soil has the higher rate of penetration in comparison to the silty-clay soil by (97.88%). the rate of penetration (rop) increment increases as the (wob) and the rotational speed increase. another point to be mentioned is that the rate of penetration (rop), in general, decreases with depth. the rates of penetration (rop) decrement percentage with depth from figure (19, 22, and 25) were as in table (7) in appendix (b). all of the above mentioned observations can be attributed to the mauwafak a. tawfik al-khwarizmi engineering journal, vol. 11, no. 1, p.p.93112 (2015) 101 same factors that were mentioned in the silty-clay soil. finally, the average values of the power consumption (watt) from figure (20, 23, and 26) were as in table (8) in appendix (b). by examining the power consumption curves it can be seen that the power consumption increases as the rotational speed increases, with a decrement in that increment which might be physically ascribed to having higher inertia. fig. 18. acceleration with depth. fig. 19. rate of penetration with dept. fig. 20. power with depth. fig. 21. acceleration with depth. fig. 22. rate of penetration with depth. fig. 23. power with depth. fig. 24. acceleration with depth. mauwafak a. tawfik al-khwarizmi engineering journal, vol. 11, no. 1, p.p.93112 (2015) 102 fig. 25. rate of penetration with dept. fig. 26. power with depth. 7.2.3. river sand for the final soil sample (river sand), the average values of the vibration acceleration levels (m/s2) from figure (27, 30, and 33) were as in table (9) in appendix (b). based on the revealed data, it can be said that vibration acceleration levels increase as the rotational speed increases. it also can be noticed that the vibration acceleration levels decrease as the weight on bit (wob) increases. in general the vibration acceleration levels were lower than those in the sand and silty-clay soil by (25.53 % and 13.19 %) respectively. vibration acceleration levels decrement increases as the (wob) and the rotational speed increase. all of the above mentioned observations can be attributed to the same factors that were mentioned in the silty-clay soil. the average values of the rate of penetration (rop) (cm/sec) from figure (28, 31, and 34) were as in table (10) in appendix (b). in reference to table (10), it can be stated that higher rotational speed means higher rates of penetration (rop). the rate of penetration (rop) is seemed to be affected by the (wob) in the same way that it did by the rotational speed and the higher the (wob) is, the higher the (rop) will be, but that's not completely practical due to the fact that (rop) will keep increasing with the (wob) up to a certain point, namely the founder point. after that point increasing the (wob) will has adverse effect on the (rop). it is worthy to mention that the river sand soil has a higher rate of penetration than that of the silty-clay by (80.57 %) and lower than that of the sand by (8.75 %). the rate of penetration (rop) increment increases as the (wob) and the rotational speed increase. another point to be mentioned is that the rate of penetration (rop), in general, decreases with depth. the rates of penetration (rop) decrement percentage with depth from figure (28, 31, and 34) were as in table (11) in appendix (b). all of the above mentioned observations can be attributed to the same factors that were mentioned in the silty-clay soil. finally, the average values of the power consumption (watt) from figure (29, 32, and 35) were as in table (12) in appendix (b). by examining the power consumption curves it can be seen that the power consumption increases as the rotational speed increases, with a decrement in that increment which might be physically ascribed to having higher inertia. fig. 27. acceleration with depth. fig. 28. rate of penetration with depth. mauwafak a. tawfik al-khwarizmi engineering journal, vol. 11, no. 1, p.p.93112 (2015) 103 fig. 29. power with depth. fig. 30. acceleration with depth. fig. 31. rate of penetration with depth. fig. 32. power with depth. fig. 33. acceleration with depth. fig. 34. rate of penetration with depth. fig. 35. power with depth. 7.2.4. free-run (idle run) in order to calculate the loads at the drill-bit inserts, establishing the power consumption curves for the free-run (idle run i.e. drilling with no contact between the drilling tool and the soil) was essential, so that the drilling power can be calculated by finding the difference between the steady state portion of the power consumption curves when drilling in the soil and outside the soil (i.e. the free-run). the average values of the power consumption (watt) were as follows in table (2) below: mauwafak a. tawfik al-khwarizmi engineering journal, vol. 11, no. 1, p.p.93112 (2015) 104 table 2, power consumption (watt). load (80 n) load (120 n) load (160 n) 50 rpm 58.6 57.5 56.4 100 rpm 78.8 78.2 77.4 150 rpm 96 95.3 94.8 200 rpm 108.7 108.5 108.3 7.3. results verification as mentioned previously ansys workbench software (the 14.0 release) was used to verify the experimental results, and that's was accomplished by reliance on power consumption curves to calculate the drag force, that encounter the bit inserts, at the intervals of two centimeters and by using the supports stiffness values that had already been calculated previously by adapting beam deflection formula, as the input to the ansys. additionally, twenty autocad 2009 geometries due to the movement of the drill-string relative to the supports as the drilling operation proceeds forehead, which were also exported to the ansys. the deviation percentage was calculated by finding the average value of the trend lines of the numerical and actual acceleration curves, figure (1) – (12) in appendix (c), as follows in table (3) below: w;�a2ba:7 �%� = x 7�-;<a42@ 244. −24b�2@ 244.24b�2@ 244. ∗ 100y table 3 results verification – deviation percentage. load 8 n r.p.m actual acc. numerical acc. deviation percentage (%) 50 4 3.7 7.5 100 10.5 9.5 9.52 150 15.5 17 9.68 200 22.5 21 6.67 load 12 n r.p.m actual acc. theoritical acc. deviation percentage (%) 50 3 2.7 10 100 7 7.5 7.14 150 12 13 8.33 200 16 17 6.25 load 16 n r.p.m actual acc. theoritical acc. deviation percentage (%) 50 2.4 2.2 8.33 100 5.1 5.6 9.8 150 8.5 9 5.88 200 14 15 7.14 8. conclusions when it comes to the conclusions and after observing the results illustrated by the charts that correlate the vibration acceleration, the rate of penetration and the power consumption curves with the depth of the borehole the following conclusions were pointed out. part of them are special conclusions of the individual soil samples while the others are general conclusions, which are going to be mentioned later, and these conclusions are as follows: 1sand has stands out to be in the first place when it comes to the highest vibration acceleration levels (with an average acc. value of (13.097 m/s2)), followed by silty-clay (11.234 m/s2) and river sand (9.753 m/s2) respectively. 2for the rates of penetration sand also seemed to be the one with the highest penetration rate (with an average rop of (1.786 cm/sec)) followed with close difference by the river sand (1.629 cm/sec) meanwhile silty-clay comes with the lowest rop average (which was (0.902 cm/sec). and now the general conclusions, which can be applied to all of the cases, are listed below: 3the vibration acceleration levels increase as the rotational speed increases (provided that the implemented operating speed is away from the resonance zones). 4the vibration acceleration levels decrease as the weight on bit (wob) increases. 5the vibration acceleration levels decrement increases as the (wob) and the rotational speed increase. 6higher rotational speed means higher (rop) since more excavation of the soil will be done. 7the (rop) will keep increasing with the (wob) up to a certain point, the founder point, and after that point increasing the (wob) will have adverse effect on the (rop). 8the rate of penetration (rop) increment increases as the (wob) and the rotational speed increase. 9in general the rate of penetration (rop) decreases with depth. finally, from the numerical analysis of the smaller and the larger drill bit models it was available to come up with the following: 10it was observed that for the same conditions (soil type, rotational speed, and wob) smaller drill bit diameter means higher vibration acceleration levels. mauwafak a. tawfik al-khwarizmi engineering journal, vol. 11, no. 1, p.p.93112 (2015) 105 notation area of the transversal section (m2) " young’s modulus (pa) $ shear modulus (pa) + gravitational acceleration (m/s2) � strain energy (n.m) �� simplified strain energy (n.m) z tensor of inertia (m4) � kinetic energy (n.m) � displacement in x-direction (m) � displacement in y-direction (m) � displacement in z-direction (m) greek letters � density (kg/m3) �� rotation about x-axis (rad) �[ rotation about y-axis (rad) �\ rotation about z-axis (rad) 9. references [1] r. w. tucker and c. wang, "an integrated model for drill-string dynamics", article, 2000. [2] d. k. ashley, x. m. mcnary, and j. c. tomlinson, "extending bha life with multi-axis vibration measurements", paper (society of petroleum engineers), 2001. [3] m. w. gui, m.asce, k. soga, m. d. bolton, and j. p. hamelin, "instrumented borehole drilling for subsurface investigation", paper (journal of geotechnical and geoenvironmental engineers), 2002. [4] r. i. leine, d. h. van campen, and w. j. g. keultjes, "stick-slip whirl interaction in drillstring dynamics", paper (journal of vibration and acoustics), 2002. [5] m.p.m. hendriks, "analysis of torsional and lateral vibrations in an experimental drillstring set-up", master thesis, 2004. [6] nenad mihajlovic, "torsional and lateral vibrations in flexible rotor systems with friction", ph.d. thesis, 2005. [7] marcelo t. piovan and rubens sampaio, "non linear model for coupled vibrations of drill-strings", paper, 2006. [8] hamed moradi, mohammad motamedi, and firooz bakhtiari-nejad, "suppression of bending vibration in drilling process via a tunable vibration absorber", paper (16th international congress on sound and vibration icsv), 2009. [9] thiago gamboa ritto, "numerical analysis of the nonlinear dynamics of a drill-string with uncertainty modeling", ph.d. thesis, 2010. [10] chien-min liao, "experimental and numerical studies of drill-string dynamics", ph.d. thesis, 2011. [11] jerome rajnauth, phd and tennyson jagai, phd, "reduce torsional vibration and improve drilling operations", paper (international journal of applied science and technology), 2012. [12] richard duff, "an experimental and computational investigation of rotating flexible shaft system dynamics in rotary drilling assemblies for down hole drilling vibration mitigation", ph.d. thesis, 2013. [13] m. lalanne and g. ferraris, john wiley and sons, chichester, west sussex, england, named "rotor-dynamics prediction in engineering", 1990. [14] m.a. trindade, c. wolter, and r. sampaio, "karhunen-loeve decomposition of coupled axial/vending vibrations of beams subject to impacts", journal of sound and vibration, 2005. mauwafak a. tawfik al-khwarizmi engineering journal, vol. 11, no. 1, p.p.93112 (2015) 106 appendix (a) fig. 1. the drill-string (drilling core) – upper parts. fig. 2. the drill-string (drilling core) – lower parts. fig. 3. the electrical motor and the inverter fig. 4. the chassis (frame) – side view. drilling shaft adjustment cylinder slide guide shaft holding bush housing cylinder housing cup plate a plate b ruler sliding holders outer slides inner slides sliding guide bush-1 loads carrying sliding guide bush-2 ruler holders shaft adjustment guide/monito ring pin holders shaft slide guide shaft driving pulley loads loads circular rubber drill-bit driving bush alignment housing cup the motor adjustment the inverter the inverter input 220 v – 1 ø output 380 v – 3 ø the electrical motor the upper plate the motor the lower plate rubber-flange fixed legs stage -1 removable extension legs stage -2 the chassis (frame) leveling bushes mauwafak a. tawfik al-khwarizmi engineering journal, vol. 11, no. 1, p.p.93112 (2015) 107 appendix (b) 1. siltyclay table 1, vibration acceleration levels (m/s2) & variation percentage. vibration acceleration levels (m/s2) & variation percentage load (80 n) load (120 n) load (160 n) 50 rpm 4.35 -28.3 % 3.12 -29.8 % 2.19 +154.7 % +152.2 % +161.6 % 100 rpm 11.08 -29 % 7.87 -27.2 % 5.73 +79.4 % +63.3 % +83.8 % 150 rpm 19.88 -35.4 % 12.85 -18.1 % 10.53 +18.2 % +43.7 % +44.7 % 200 rpm 23.5 -21.4 % 18.47 -17.5 % 15.24 table 2, rates of penetration rop (cm/sec) & variation percentage. rates of penetration rop (cm/sec) & variation percentage load (80 n) load (120 n) load (160 n) 50 rpm 0.225 +48 % 0.333 +42.9 % 0.476 +52 % +110.8 % +189.7 % 100 rpm 0.342 +105.3 % 0.702 +96.4 % 1.379 +88.6 % +23.9 % +20.9 % 150 rpm 0.645 +34.9 % 0.870 +91.6 % 1.667 +17.1 % +24.3 % +41.2 % 200 rpm 0.755 +43.2 % 1.081 +117.7 % 2.353 table 3, rates of penetration (rop) decrement percentage. rates of penetration (rop) decrement percentage load (80 n) load (120 n) load (160 n) 50 rpm 23.4 % 37.9 % 15 % 100 rpm 26.3 % 31.4 % 33.1 % 150 rpm 32.7 % 32.5 % 48.3 % 200 rpm 32 % 45 % 70 % table 4, power consumption (watt). power consumption (watt) load (80 n) load (120 n) load (160 n) 50 rpm 51.67 50.02 47.55 100 rpm 65.35 63.96 60.69 150 rpm 77.14 76 71.73 200 rpm 87.82 84.42 83.23 2. sand table 5, vibration acceleration levels (m/s2) & variation percentage. vibration acceleration levels (m/s2) & variation percentage load (80 n) load (120 n) load (160 n) 50 rpm 5.69 -17.9 % 4.67 -12.6 % 4.08 +145 % +91.2 % +104.7 % 100 rpm 13.94 -35.9 % 8.93 -6.5 % 8.35 +44.5 % +52 % +66 % 150 rpm 20.15 -32.7 % 13.57 +2.1 % 13.86 +31.5 % +42.3 % +30.7 % 200 rpm 26.49 -27.1 % 19.31 -6.2 % 18.12 mauwafak a. tawfik al-khwarizmi engineering journal, vol. 11, no. 1, p.p.93112 (2015) 108 table 6, rates of penetration rop (cm/sec) & variation percentage. rates of penetration rop (cm/sec) & variation percentage load (80 n) load (120 n) load (160 n) 50 rpm 0.471 +18 % 0.556 +2.7 % 0.571 +123.6 % +139.7 % +191.9 % 100 rpm 1.053 +26.6 % 1.333 +25.1 % 1.667 +51.9 % +76.5 % +50 % 150 rpm 1.6 +47.1 % 2.353 +6.2 % 2.5 +47.1 % +41.6 % +45.4 % 200 rpm 2.353 +41.6 % 3.333 +9.1 % 3.636 table 7, rates of penetration (rop) decrement percentage. rates of penetration (rop) decrement percentage load (80 n) load (120 n) load (160 n) 50 rpm 15 % 14.4 % 10.8 % 100 rpm 28.3 % 32 % 18.1 % 150 rpm 32.5 % 32.5 % 35 % 200 rpm 63.8 % 67.2 % 60 % table 8, power consumption (watt). power consumption (watt) load (80 n) load (120 n) load (160 n) 50 rpm 51.5 49.52 48.9 100 rpm 67.49 64.5 61.83 150 rpm 79.5 75.24 73.59 200 rpm 89.14 84.17 83.48 3. river sand table 9, vibration acceleration levels (m/s2) & variation percentage. vibration acceleration levels (m/s2) & variation percentage load (80 n) load (120 n) load (160 n) 50 rpm 4.64 26.9 % 3.39 5.3 % 3.21 153.9 % 77.3 % 87.2 % 100 rpm 11.78 49 % 6.01 0 % 6.01 30.2 % 75.7 % 57.2 % 150 rpm 15.34 31.2 % 10.56 10.5 % 9.45 27.4 % 25 % 47 % 200 rpm 19.55 32.5 % 13.2 -5.2 % 13.89 table 10, rates of penetration rop (cm/sec) & variation percentage. rates of penetration rop (cm/sec) & variation percentage load (80 n) load (120 n) load (160 n) 50 rpm 0.444 36.5 % 0.606 11.9 % 0.678 83.8 % 106.3 % 168.1 % 100 rpm 0.816 53.2 % 1.25 45.4 % 1.818 53.2 % 39.1 % 29.4 % 150 rpm 1.25 39.12 % 1.739 35.3 % 2.353 68.4 % 64.3 % 54.5 % 200 rpm 2.105 35.7 % 2.857 27.3 % 3.636 mauwafak a. tawfik al-khwarizmi engineering journal, vol. 11, no. 1, p.p.93112 (2015) 109 table 11, rates of penetration rop (cm/sec) & variation percentage. rates of penetration (rop) decrement percentage load (80 n) load (120 n) load (160 n) 50 rpm 25.4 % 22.4 % 20 % 100 rpm 26.3 % 28.3 % 27.1 % 150 rpm 45 % 59.7 % 33.1 % 200 rpm 48.8 % 65 % 55 % table 12, power consumption (watt). power consumption (watt) load (80 n) load (120 n) load (160 n) 50 rpm 51.57 50.52 48.48 100 rpm 68.51 66.36 62.14 150 rpm 79.33 76.95 73.68 200 rpm 89.5 84.84 83.31 appendix (c) fig. 1. act. and theo. acc. with depth (80 n & 50 rpm) fig. 2. act. and theo. acc. with depth (80 n & 100 rpm) fig. 3. act. and theo. acc. with depth (80 n & 150 rpm) fig. 4. act. and theo. acc. with depth (80 n & 200 rpm) fig. 5. act. and theo. acc. with depth (120 n & 50 rpm) fig. 6. act. and theo. acc. with depth (120 n & 100 rpm) mauwafak a. tawfik al-khwarizmi engineering journal, vol. 11, no. 1, p.p.93112 (2015) 110 fig. 7. act. and theo. acc. with depth (120 n & 150 rpm) fig. 8. act. and theo. acc. with depth (120 n & 200 rpm) fig. 9. act. and theo. acc. with depth (160 n & 50 rpm) fig. 10. act. and theo. acc. with depth (160 n & 100 rpm) fig. 11. act. and theo. acc. with depth (160 n & 150 rpm) fig. 12. act. and theo. acc. with depth (160 n & 200 rpm) mauwafak a. tawfik appendix (d) instruments connection the diagram below (figure (1)) illustrates the position where the accelerometers were attached fig. y x z al-khwarizmi engineering journal, vol. 11, no. 1, p.p. 111 the diagram below (figure (1)) illustrates the position where the accelerometers were attached to the drill-string for measuring the vibration acceleration and how the connected to each other. fig. 1. instruments connection diagram. y x two accelerometers were attached to the drill-string at the highlighted position. the accelerometers were in turn connected to the charge amplifier. the charge amplifier transforms the charge, which comes from the accelerometers, into voltage and amplifies it to be displayed on the oscilloscope screen. the accelerometers are perpendicular to each other (one in the x-direction and one in the y khwarizmi engineering journal, vol. 11, no. 1, p.p.93112 (2015) string for measuring the vibration acceleration and how the instruments were the accelerometers were in turn connected to the charge amplifier. the charge amplifier transforms the charge, which comes from the accelerometers, into d amplifies it to be displayed on the the accelerometers are perpendicular to each other (one in the direction and one in the y-direction). و�ق �� �و��ق )2015( 93112، ���� 1، ا�� د11 ا���ارز� ا��� �� ا������� 112 ُ� ����� ُ�1 ��ا��$�ِ 0ازاتھ�ِ &�, ا+ �� ة ا��َ �� و)'� &ُ %$#�" ا��َ �َ ، � ����ى ا� ������2 ا��َ �َ 3�1�� **د&5 ��و1$ء * ��31 &� ***را� ��$ء &��ان � ھ���� ا������ وا����ات ***،**،*� ا�%��$�$#"�ا�!� �� /� drmat19853@yahoo.com &'ا�+)*� ا(��%)و: * wafaabd_92@yahoo.com **&'ا�+)*� ا(��%)و: rami.safaa@yahoo.com &'ا�+)*� ا(��%)و: *** ��7ا��ُ و�m,ا ا�l)ض . >)��j ا�/َ a$ك ا��*�� "�& اhھ%gازي وa= (< ِ &b ca"a/d@ ا��ُ �ة ا�/َ <) =ُ و�ُ ، >);�*": ا�/َ َ ، )ب�را�� �%56") '$ع ا�%ُ �23 دِ ا�+/. *ُ اھ, �"�jd �d ِ حَ وب��ء �j� ُ (< ُاء ا�%!�رب ا��(#h �*(+%q َا�� r'�!ب�� �;a�%./+ا� � &a� ، َا�� r'�!2 =�$د ا�/َ ح". ان ا�"ltd @a= 2�%uا &a� ا'$اع &b (< �"�ت ا�%& �/َ %"\ ر�� ا��ُ *ُ وب��2�t ا�,ي، a%q>�وب6ح��ل ُ ، a%q>�)ع دورا'"� ُ ب�ُ ، +"+�تzف ح!� ا�/ُ �+� ا�@ اa%q ِ%w>� 'ِ )ب ذات w$اص ُ a%q>� � ا�%ُ ُ ��رع اhھ%gازd ]ب(d ، ُ )اق%wh(��ل اrop ( ُ= _ ���>ك ا�zm%ا�/َ وإ� a�(<. bذ� �= ًzdb ِ%ا� �d �;b ال e �'(ام ب�qansys workbench (the 14.0 release) ُ�� ُة ا�%!�رب ا���g�/ ِh � a;/%وا� �*(+%q�m%/ ، �;b b�,gو � ا�%ِ d 2"3�%� c ا�q ُ <�ر�ى ب�(w)*� اj' ا�/َ ح�(ت ��*(+� �<a%q(<. al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 4554 (2014) optimization of wear parameters in aisi 4340 steel abbas khammas hussein department of materials engineering/ university of technology emial: abbas2000x@yahoo.com (received 26 may 2014; accepted 22 september 2014) abstract this study investigated the optimization of wear behavior of aisi 4340 steel based on the taguchi method under various testing conditions. in this paper, a neural network and the taguchi design method have been implemented for minimizing the wear rate in 4340 steel. a back-propagation neural network (bpnn) was developed to predict the wear rate. in the development of a predictive model, wear parameters like sliding speed, applying load and sliding distance were considered as the input model variables of the aisi 4340 steel. an analysis of variance (anova) was used to determine the significant parameter affecting the wear rate. finally, the taguchi approach was applied to determine the optimum levels of wear parameters. the results show that using the optimal parameter setting (load3, sliding speed1, and sliding distance2) a lower wear rate is achieved. the error between the predicted and experimental values is only 3.19%, so good agreement between the actual and predicted results is observed. keywords: aisi 4340, wear, pin on disc, taguchi method, neural network. 1. introduction aisi 4340 steel have been used for a great number of applications, like aircraft landing gear, power transmission gear, and in the machine constructions industry with hardness between 28 and 38 rockwell c (hrc). this kind of low alloyed steel is very cheap, compared with the expensive high alloyed tools steel, and it has an appropriated hardness combined with a very high toughness and tensile strength [1,2]. moreover, the cutting tools used for hard turning are relatively costly as compared to grinding and hence there is a need to investigate the effect of wear parameters on tool life. it has also been reported that the properties and the composition of tool materials are critical to the behavior of machining forces which in turn affect the tool life. therefore, it is necessary to study the influence of process parameters on tool wear in hard turning process. several investigations have been carried out to study the tool wear and improve tool life as well as productivity. luo et al studied wear behavior in turning of aisi 4340 hardened alloy steels using cubic boron nitride (cbn) and ceramic tools. oliviera et al investigated the hard turning of aisi 4340 steel in continuous and interrupted cuts with whisker reinforced cutting tools [3, 4, 5, and 6]. in the present work, two of the techniques, namely, the neural network (nn) with a backpropagation network (bpn) and the taguchi design method have been employed. matlab (2013) and minitab16 programs were used for the nn modelling and the taguchi optimization technique, respectively. sliding speed, applying load, and sliding distance were selected as the input factors, whereas wear rate was selected as the response. a bpn model was developed for the prediction of the wear rate. an analysis-ofvariance (anova) table was used to determine the significant wear parameters affecting the wear rate. an approach to determine the optimum wear parameter setting was proposed on the basis of the taguchi design method. mailto:abbas2000x@yahoo.com abbas khammas hussein al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 4554 (2014) 46 2. experimental set-up and test procedure in the present investigation, a pin on disc wear tests were performed on aisi 4340 steel which has been selected as work piece material. table 1 shows the spectrochemical analysis (measured results) of this steel. all experiments were performed by using a pin on disc wear apparatus shown in figure 1. table 1, chemical composition (wt%) of aisi 4340. si mo ni cr cu p s mn al c 0.2541 0.2892 1.6991 0.9112 0.0811 0.0221 0.0132 0.5913 0.0167 0.3534 fig.1. pin on disc wear apparatus. this machine facilitates study of wear characteristics in sliding contact under desired conditions. sliding occurs between the stationary pin on a rotating disc. normal load, sliding distance and sliding speed can be varied to suit the test conditions. the pin specimen was tested in pin on disc apparatus. to perform the test specimen was clamped in jaw. pin weight losses were measured using an electronic balance having an accuracy of ±0.001 mg. weight losses were converted to volume losses by dividing the weight to the density of steel (7.85 g/cm 3 ). dry sliding wear tests were carried out using pin-on disk type wear tester at different parameters, where three levels of three parameters were selected as shown in table 2. the tests were conducted at a constant time of 30 min. table 2, parameters with level values. parameters level 1 level2 level3 load (n) 20 25 30 sliding speed (r.p.m) 250 350 400 sliding distance (cm) 6 8 10 in the present investigation an l9 orthogonal array was chosen as shown in table 3. the experiment consists of 9 tests (each raw in the l9 orthogonal array) and the columns were assigned abbas khammas hussein al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 4554 (2014) 47 with parameters). the orthogonal array table in the taguchi design method was applied to bpn as testing data. bpn was developed to predict the wear rate. the optimum wear-parameter combination was obtained by using an analysis of the signal-to-noise (s/n) ratio. table 3, l9 orthogonal array and a neural-network training set. the signal-to-noise (s/n) ratio is a measure of the magnitude of the data set relative to the standard deviation. if the s/n is large, the magnitude of the signal is large relative to the noise , as measured with the standard deviation [7,8] . there are several s/n ratios available depending on the types of characteristics. the nominal ratio is the best, higher is better and lower is better [8] . we would select the s/n if the system is optimized when the response is as small as possible. the s/n ratio for the lb (lower is better) characteristic is calculated by using the following equations [9]: 𝐿𝑗 = 1 𝑛 𝑦𝑖 2 … 1 𝑛 𝑘=1 𝜂𝑗 = −10𝑙𝑜𝑔𝐿𝑗 … (2) where 𝑦𝑖 is the response value, 𝐿𝑗 is the loss function and 𝜂𝑗 is the s/n ratio. 3. statistical analysis the results of the experiments were evaluated by the analysis of variance (anova) . the main objective of the analysis was to determine the influence of every parameter on the variance of results, regarding the total variance of all the parameters. this is defined by the sum of squares. the calculation of anova was made on the basis of the recommendations in [8]: 𝑆𝑆 = 𝑦𝑖 − 𝑦 2 𝑁 𝑖=1 = 𝑦𝑖 2 − 𝐶𝐹 … (3) 𝑁 𝑖=1 𝐶𝐹 = 𝑇2 𝑁 … (4) to calculate the effect of an individual parameter on the variance a more useful equation is used: 𝑆𝑆𝐴 = 𝐴1 2 𝑁𝐴1 + 𝐴2 2 𝑁𝐴2 + ⋯ + 𝐴𝑛 2 𝑁𝐴𝑛 − 𝑇2 𝑁 … (5) the following equations are also needed for the calculations: 𝑀𝑆𝐴 = 𝑆𝑆𝐴 𝑓𝐴 … (6) 𝐹𝐴 = 𝑀𝑆 𝐸 … (7) 𝑃𝐴 = 𝑆𝑆𝐴 𝑆𝑆 × 100 … (8) where: ss: sum of squares. 𝑦𝑖 : value of each results. cf: correction factor. t: the sum of all results. n: the total number of results. 𝐴1 : the sum of results (𝑦𝑖) where parameter (𝐴1 ) is present . 𝑁𝐴1: number of experiments where parameter (𝐴1 ) is present . msa: mean square where parameter (𝐴1 ) is present. 𝑓𝐴: degree of freedom of factor a . 𝐹𝐴: f ratio. 𝑃𝐴: percentage of contribution for factor a . abbas khammas hussein al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 4554 (2014) 48 the degree of freedom are an important part of the statistical analysis because they provide us with additional information about the process. the degree of freedom for the taguchi array is defined as follows [9]: dof parameter = number of factor levels-1 dof experiment= number of results-1 dof error = number of all dofs-number of dofs of all parameters. 4. experimental results and data analysis a neural network based on back propagation is a multilayered architecture made up of one or more hidden layers placed between the input and output layers [10] . the components of the input pattern consisted of the control variables of applied load, sliding speed and sliding distance whereas the output pattern component represented the wear rate. table 3 shows a taguchi l9 orthogonal-array plan of the experiment and a training set for the neural-network application. the orthogonal-array table used in the taguchi design method was applied to bpn as testing data .the network structure was selected to be the 3:4:1 type .the used bnp model is shown in figure 2. fig. 2. 3:4:1 (3 inputs, 1 hidden layer with 4 neurons and 1 output) type of the bpn algorithm used for modeling. the testing validity of the regression analysis and the neural network results was achieved by using the input parameters according to the design matrix given in table 4 the performance of each bpn was calculated with the absolute error (%) of the tested subset using matlab toolbox of neural network. the average absolute error (%) was calculated as 1.02 %. the wear rate can be predicted in a quick and accurate manner, the bpn results show that the predicted values were very close to the experimental values. the value of the multiple coefficients r 2 is 0.9441, which means that the explanatory variables explain 94.41% of the variability in the response variable. the predicted values of the wear rate were compared with experimental values as shown in figure 3. table 4, test set for the validity of the constructed neural network. sliding distance (cm)sliding speed (r.p.m)load (n)exp. no. predictedexperimental 0.00410.004310250201 0.00390.00416250252 0.00440.004610400303 0.00430.00428350254 0.00410.00416400305 wear rate ( mm 3 /mm) abbas khammas hussein al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 4554 (2014) 49 fig.3. comparison of experimental and predicted values (bpn model). the effect and optimization of wear settings for the minimum wear rate was investigated experimentally. the optimum wear-parameter combination was obtained by analyzing the s/n ratio . anova was used to consider the effects of the input factors on the response and was performed on experimental data. the confidence level was selected as 0.95%. the results of anova for the wear rate are shown in table 5. the results of contribution percentage (%) are shown table 6. table 5, results of anova for the wear rate. table 6, results of contribution percentage (%) of wear parameters. it was observed that the applying load and sliding speed have a great influence on the obtained wear rate after analyzing table 4 and 5. the sliding distance do not effect significantly the obtained wear rate . the plot of the main-factor effects is shown in figure 4. the s/n graph for the wear rate is shown in figure 5. it is evident that the applying load (66.67%) and sliding speed (30.56%) have the most significant effect on the wear rate. sliding distance (2.78%) has little effect on the wear rate. percentage contribution of each variable on wear rate variables percentage contribution(%) load 66.66666667 speed 30.55555556 distance 2.777777778 total 100 abbas khammas hussein al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 4554 (2014) 50 fig.4. main effect plot for wear rate vs. load, sliding speed and sliding distance. fig.5. main effect plot for sn ratios vs. load, sliding speed and sliding distance. optimum factor levels and s/n ratios obtained at the end of the taguchi design technique are summarized in table 7. based on the s/n ratio plot in figure 5, the optimum wear parameters for the aisi 4340 steel are applying load at level 3, sliding speed at level1 , and sliding distance at level 2 . the applying load and sliding speed are two parameters affecting the wear rate compared to sliding distance. table 7, optimum factor levels and their s/n ratios. abbas khammas hussein al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 4554 (2014) 51 according to figure 6 (a), higher applying load at higher sliding speed gives a greater wear rate compared to the combination effect of applying load and sliding distance as shown in figure 6 (b) and the combination effect of sliding speed and sliding distance as shown in figure 6 (c) . table 8 shows a multiple linear regression equation developed for wear rate. this developed model gives the relationship between independent/ predictor variable and a response variable. figure 7 shows comparison of predictive performance when using the developed model with experimental data. it can be see there is a better model fit. as these values are closely resembling the actual data with minimum error (r 2 =0.9049), design of experiments by taguchi method was successful for calculating wear rate from the regression equation. fig. 6. 3d surface plot for wear rate vs. load, sliding speed and sliding distance. table 8, regression equation of wear rate. (a) (b) (c) abbas khammas hussein al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 4554 (2014) 52 fig.7. comparison of experimental and predicted values (regression model). 5. confirmation tests a confirmation experiment is the final step in first step iteration of designing an experiment process i.e., is the final step in taguchi method and it is used to verify the optimal combination of the factor settings [9]. the purpose of the confirmation experiment is to validate the conclusions drawn during the analysis phase. the confirmation experiment is performed by conducting a test with a specific combinations of the factors and levels previously evaluated [9] . in this study, after determining the optimum conditions and predicting the response (wear rate) under these conditions , a new experiment was designed and conducted with the optimum levels of the wear rate parameters . the final step is to predict and verify the improvement of the performance characteristic. the predicted value of wear rate (𝜂 ) at the optimum levels is calculated by using the relation given as [8]: 𝜂 = 𝜂𝑚 + 𝜂 𝑖 − 𝜂𝑚 𝑛 𝑖=1 … (9) where 𝜂𝑚 is the total mean of response, 𝜂 𝑖 is the mean of the response at the optimum level, and n is the number of the main wear parameters that that significantly affect the performance. the result of the experimental confirmation using the optimum wear rate parameters is shown in table 9. it can be seen that the results are consistent, i.e. a good agreement between the predicted and actual wear rate being observed. table 9, predicted values and confirmation test results for wear rate. 6. conclusions this study presents a prediction, optimization and modelling of the wear behavior of the aisi 4340 steel based on the taguchi-based neural network with the back-propagation algorithm method . the following conclusions can be drawn from this study: 1. the main wear parameters that affect the wear rate of the aisi 4340 steel were determined as applying load (66.67%) and sliding speed (30.56%) among three controllable factors influencing the wear rate using anova. taguchi optimal parameters settings level prediction experiment error(%) load (n) 3 sliding speed (r.p.m) 1 0.003789 0.00391 3.193454737 sliding distance (cm) 2 abbas khammas hussein al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 4554 (2014) 53 2. a neural network based on the backpropagation network (bpn) algorithm was constructed for predicting the wear rate. the predicted values were found to be very close to the experimental values. 3. the optimum parameter combination for the minimum wear rate was obtained by using the taguchi design method with analysis of the s/n ratio. 4. the confirmation test supports the finding that the wear rate is greatly decreased by using the optimum design parameters. from confirmation test, the error (%) associated with wear rate is 3.193454737% resulting in the conclusions that the design of experiments by the taguchi method was successful for calculating wear rate from the regression equation. 5. the obtained results indicate that the bpn model agreed with the taguchi analysis. 7. references [1] gilberto bearano, julio caicedo, juan munzo saldana, " mechanical and tribological properties enhancement of heat treated aisi4340 steel by using a tin/tialn", rev.fac.ing.univ.antioquia no.44.pp.3642.jun.2008. [2] jitendra . m.varma, chirag. p. patel, " parametric optimization of hard turning aisi 4340 steel by solid lubricant with coated carbide insert", vol3, issue3, pp.1011-1015, may-jun2013. [3] r.suresh, s.basavarajappa, v.n.gaitonde, g.l.samuel, "machinability investigations on hardened aisi 4340 steel using coated carbide insert", int.journal of refractory metals and hard materials 33(2012) pp.7586. [4] arun.s, t.sivakumar, viswanathan p. and r.subramanian , "study of hardness and wear properties of boronized aisi 4340 steel", vol.3,issue4,jul-aug 2013, pp.19271929 . [5] luo sy, liao ys, tsai yy, " wear characteristic in turning high hardness alloy steel by ceramic and cbn tools", jou.mater process technol , 1995, pp.10091019. [6] oliverira aj, diniz ae, ursolino dj. " hard turning in continuous and interrupted cut with pcbn and whisker reinforced cutting tools", jou.mater process technol , 2009, 209:5262-70 . [7] allen, theodore t., "introduction to engineering statistics and six sigma: statistical quality control and design of experiments and systems", springer-verlag london limited 2006. [8] peter goos and bradley jones, " optimal design of experiments: a case study approach " , wiley & sons, ltd 2011 . [9] douglas c.montgomery , "design and analysis of experiments", john wily &sonc, inc., 2009 . [10] daniel graupe , " priciples of artificial neural networks ",(2nd edition), world scientific publishing co. pte. ltd.2007 . (2014)4554 ، صفحة4، العذد10دجلة الخوارزمي الهنذسية المجلعباس خماس حسين م 54 aisi4340تحذيذ العوامل المثلى للبلى في الفوالر نوع عباس خماس حسين اٌحىٕىٌىخٍةاٌداِعة / لسُ هٕذسة اٌّىاد abbas2000x@yahoo.com : االٌىحشؤً اٌبشٌذ الخالصة و . طشٌمة جاوىخً جحث ظشوف اإلخحباس اٌّخحٍفة عٍى وفك aisi 4340-جحضّٓ هزٖ اٌذساسة جحذٌذ اٌعىاًِ اٌّثٍى ٌسٍىن اٌبٍى فً اٌفىالر ٔىع و جُ إعحّاد إسٍىب اإلٔحشاس اٌعىسً ٌٍشبىة . aisi 4340فً هزا اٌبحث اٌشبىة اٌعصبىٍٔة و طشٌمة جاوىخً ٌخفض ِعذي اٌبٍى فً اٌفىالر تأُسحخذَ اٌحًّ اٌّسٍظ و و أِا ِحغٍشات اإلدخاي أي ِعاِالت اٌبٍى اٌحً جُ إسحخذاِها ٌٍحصىي عٍى ّٔىرج اٌحٕبأ فهً سشعة اإلٔزالق. اٌعصبىٍٔة ٌٍحٕبأ بّعذي اٌبٍى .و أخٍشاً، جُ جطبٍك طشٌمة جاوىخً ٌححذٌذ اٌّسحىٌات اٌّثٍى ٌعىاًِ اٌبٍى . وّا أسحخذَ جحًٍٍ اٌحبآٌ ٌححذٌذ جأثٍش اٌعىاًِ عٍى ِعذي اٌبٍى . ِسافة اإلٔزالق وّا أْ لٍّة اٌخطأ ِابٍٓ اٌمٍُ . ي اٌى خفض ِعذي اٌبٍى جؤد( 2، و ِسافة اإلٔزالق 1سشعة اإلٔزالق و 3اٌحًّ )و أظهشت إٌحائح ، أْ اٌعىاًِ اٌّثٍى .أي هٕاٌٍه جىافك خٍذ ِابٍٓ إٌحائح اٌحً جُ اٌحٕبأ بها و إٌحائح اٌحدشٌبٍة %3.19اٌحً جُ اٌحٕبأ بها و اٌمٍُ اٌحدشٌبٍة هً فمظ mailto:abbas2000x@yahoo.comالبريد mailto:abbas2000x@yahoo.comالبريد 8595 al-khwarizmi engineering journal,vol. 11, no. multifocus image fusion based on pixel significance using department of computer science/ (received abstract the objective of image fusion is to representation contains higher amount of useful information than any input one. fusion method is proposed. it depends on using weights that are extracted from source images using counterlet transform. the extraction method is done by making the approximated transformed coefficients equal to zero, then taking the inverse counterlet transform to get the details of the i algorithm has been verified on several grey scale and color test keywords: image fusion, counterlet transform (ct), pixel significance, weighted average. 1. introduction image fusion is known as the process by which we combine information from multiple images into a smaller group of images, generally an odd one. this image retains the most eligible information from the inputs with fewer in addition to decreasing the amount of data, fusion algorithm creates more convenient images for machine or human perception and for image processing. in the ccd devices, lenses have limited depth-of focus difficult to obtain all relevant objects in focus in a one image. but by fusing all focused objects from the sequence of images obtained by gradually shifting the focal plane over the s produce the desired image. this leads issue of multifocus image fusion [1]. have been executed in the field of multi image fusion, as well as image fusion for fields such as medical images, remote sensing, and fusion of thermal and visible images for surveillance application.image fusion can be executed at any of the three processing levels: signal (pixel), feature (object) and decision (symbol). pixel level fusion, defines the process khwarizmi engineering journal,vol. 11, no. 3, p.p. 8595 (2015) focus image fusion based on pixel significance using counterlet transform iman m.g. alwan department of computer science/ college of education for women/ university of baghdad email:ainms_66@yahoo.com (received 8 may 2014; accepted 16 april 2015) the objective of image fusion is to merge multiple sources of images together in such a way that the final representation contains higher amount of useful information than any input one.. in this paper, nds on using weights that are extracted from source images using counterlet . the extraction method is done by making the approximated transformed coefficients equal to zero, then taking the inverse counterlet transform to get the details of the images to be fused. the performance of the proposed grey scale and color test images, and compared with some image fusion, counterlet transform (ct), pixel significance, weighted average. fusion is known as the process by which information from multiple images into a smaller group of images, generally an odd retains the most eligible fewer artifacts. he amount of data, hm creates more convenient images for machine or human perception and for extra in the ccd devices, the optical of focus. so, it’s objects in focus in a fusing all focused objects from of images obtained by gradually the sight, we can e desired image. this leads to the [1]. many works have been executed in the field of multi-focus as well as image fusion for other fields such as medical images, remote sensing, and fusion of thermal and visible images for surveillance application.image fusion can be any of the three processing levels: signal (pixel), feature (object) and decision (symbol). pixel level fusion, defines the process of fusing visual information associated with each pixel from a number of registered images into a single fused image, repres level [2,3,4]. since transform domain is useful tool for representing, analysis and interpretation of information, transforms have been used gradient, contrast ratio of low pass pyramids discrete wavelet transform and geometric analysis transforms image fusion rules can be implemented such as ‘maximum’ or ‘mean’ where the fused coefficient is the maximum or the average of the source coefficients respectively. rule is susceptible to noise while the mean fusion rule reduces contrast, so another fu ‘mean-max’, is used. in t for frequency of low band frequency of high band. another method by researches [9, 10] is the ‘weighted average’ of the source coefficients. in [11] adaptive weighted average in wavelet domain is proposed by computing pixel’s significance through available information at bands of finer resolution rule which can efficiently fuse multifocus i by calculating weighted average of pixels al-khwarizmi engineering journal (2015) focus image fusion based on pixel significance using university of baghdad multiple sources of images together in such a way that the final . in this paper, a weighted average nds on using weights that are extracted from source images using counterlet . the extraction method is done by making the approximated transformed coefficients equal to zero, then mages to be fused. the performance of the proposed some present methods. of fusing visual information associated with each pixel from a number of registered images into a single fused image, representing a fusion at lowest level [2,3,4]. since transform domain is very representing, analysis and interpretation of information, various multiscale been used, like laplacian, gradient, contrast ratio of low pass pyramids, discrete wavelet transform and multiscale geometric analysis transforms [5,6,7,8]. various image fusion rules can be implemented such as ‘maximum’ or ‘mean’ where the fused coefficient is the maximum or the average of the source the maximum fusion rule is susceptible to noise while the mean fusion rule reduces contrast, so another fusion rule, this rule ‘mean’ is used frequency of low band and ‘maximum’ is for band. another method proposed the ‘weighted average’ of . in [11] adaptive weighted average in wavelet domain is proposed by pixel’s significance through available information at bands of finer resolution. a fusion e which can efficiently fuse multifocus images weighted average of pixels in iman m.g. alwan wavelet domain. the weights are adaptively decided using the statistical properties of the neighborhood. the main idea is that the estimate’s eigen value of the covariance matrix of an image block depends on the strength of edges in the block and thus makes a suitable weight to be given to the pixel. this gives weightage to pixel with sharper [12]. this method increases the quality, especially sharpness with minimum fusion artifacts. in [13] a proposed weighted average method was represented. it computes the weights by measuring the strength of details in a detail image obtained by subtracting cross bilateral filter (cbf) output from original image. the weights thus computed are multiplied directly with the original source images followed by weight normalization. this method has shown good performance. in this paper, a novel method of obtaining a detail image is propos on using counterlet transform to the images to be fused, since counterlet transform is multi direction and anisotropy in addition to multi and localization properities, it can contours of original images effectively with a coefficients [14]. the proposed algorithm depends on applying ct to both multifocus images, make approximation bands equal to zero then apply inverse counterlet transform to obtain the detail images, then the weights can be computed to fuse images . 2. counterlet transform the contourlet transform, which is proposed by do and vetterli [14], is a multi-directional and a multi-resolution transform. it provides approximation of images made of smooth contours, through implementing laplacian pyramid (lp) decomposition followed by directional filter bank (dfb) applied on each subband’s bandpass fig.1(a). the images are decomposed into subbands by lp and e image is analyzed by dfb. the dfb has the property of capturing high frequency of input image while it leaks low frequency of signals, thus the dfb is merged with the lp. it means removing the low frequency from the input image before applying dfb. fig. 1(b) resulting frequency division, where the al-khwarizmi engineering journal, vol. 11, no. 86 . the weights are adaptively decided using the statistical properties of the idea is that the unbiased f the covariance matrix of an image block depends on the strength of edges the block and thus makes a suitable choice for weight to be given to the pixel. this gives more neighborhood fused image , especially sharpness with minimum fusion artifacts. in [13] a proposed weighted average method was represented. it computes the weights by measuring the strength of details in a detail image obtained by subtracting cross cbf) output from original image. the weights thus computed are multiplied directly with the original source images followed by weight normalization. this method has shown good performance. in this paper, a novel method of obtaining a detail image is proposed; it depends on using counterlet transform to the images to be fused, since counterlet transform is multidirection and anisotropy in addition to multi-scale and localization properities, it can capture the of original images effectively with a few [14]. the proposed algorithm depends on applying ct to both multifocus images, make approximation bands equal to zero then apply inverse counterlet transform to obtain the detail images, then the weights can be computed to fuse the contourlet transform, which is proposed directional and resolution transform. it provides efficient approximation of images made of smooth contours, through implementing laplacian pyramid (lp) decomposition followed by directional filter bank (dfb) applied on each the images are decomposed into subbands by lp and each detail the dfb has the property of capturing high frequency of input leaks low frequency of signals, the dfb is merged with the lp. it means removing the low frequency from the input image fig. 1(b) shows the resulting frequency division, where the whole spectrum is divided both angularly and radially and the number of directions is frequency. the discrete contourlet transform makes perfect reconstruction with less than 4/ redundancy ratio [15]. fig. 1. the counterlet transfosrm: (a) block diagram, (b) resulting frequency division. a. laplacian pyramid laplacian pyramid (lp), which was introduced by burt and adelson [16], achieves multiscale decomposition. the lp decomposition at each level results a band pass image by generating a down sampled low pass version of the original and the difference between the original and the prediction, as in fig. 2(a). in this figure (a) and (b) are the analysis and synthesis the sampling matrix. the process can be iterated on a coarse version. in fig.2 (a) the outputs are a coarse approximation ‘a1’ and a difference ‘a2’ between the original signal and prediction. the process can be iterated by decomposi version repeatedly. the original image is convolved with a gaussian kernel. the resulting image is a low pass filtered version of the original image. the laplacian will be the difference between the original image and the low pass filtered image. a set of band pass filtered images is obtained by continuing the above process. applying these steps several times, a sequence of images are obtained [15]. khwarizmi engineering journal, vol. 11, no. 3, p.p. 8595 (2015) spectrum is divided both angularly and radially and the number of directions is increased with the discrete contourlet transform makes perfect reconstruction with less than 4/3 1. the counterlet transfosrm: (a) block diagram, (b) resulting frequency division. laplacian pyramid (lp), which was introduced by burt and adelson [16], achieves multiscale lp decomposition at each level results a band pass image by generating a down sampled low pass version of the original and the difference between the original and the prediction, as in fig. 2(a). in this figure (a) and (b) are the analysis and synthesis filters, while ‘s’ is the sampling matrix. the process can be iterated on a coarse version. in fig.2 (a) the outputs are a coarse approximation ‘a1’ and a difference ‘a2’ between the original signal and prediction. the process can be iterated by decomposing the coarse version repeatedly. the original image is convolved with a gaussian kernel. the resulting image is a low pass filtered version of the original image. the laplacian will be the difference between the original image and the low pass age. a set of band pass filtered images is obtained by continuing the above process. after applying these steps several times, a sequence of iman m.g. alwan fig. 2. laplacian pyramid. (a) one level of decomposition. (b) the reconstruction of laplacian pyramid. b. directional filter bank (dfb) the directional filter bank is a critically sampled filter bank. images can be decomposed into directions of any power of two’s number dfb leads to partitions of wedge frequency by implementing decomposition of n level tree structure. a rule of tree expanding should be followed to get the required frequency partition. the high frequency content (smooth countours and directional edges) can be captured by dfb while low frequency components are exhausted poorly by the dfb [15]. fig. 3. the block diagram of the proposed fusion system ��� ��� a b b wb wa a make ll subbands of a,b equal to zero discrete counterlet transform al-khwarizmi engineering journal, vol. 11, no. 87 2. laplacian pyramid. (a) one level of decomposition. (b) the reconstruction of laplacian b. directional filter bank (dfb) the directional filter bank is a critically images can be decomposed into directions of any power of two’s number. the ions of wedge-shaped frequency by implementing decomposition of nlevel tree structure. a rule of tree expanding should be followed to get the required frequency the high frequency content (smooth countours and directional edges) can be captured by dfb while low frequency components are 3. the proposed algorithm in [13] the proposed image fusion algorithm directly fuses two source images of a same scene using weighted average. the proposed method differs from other weighted average methods in terms of weight computation and the domain of weighted average. the weights are computed by measuring the strength of details in a detail image obtained by subtracting cross bilateral filter (cbf) output from original imag thus computed are multiplied directly with the original source images followed by weight normalization. the idea is to capture most of the focused area details in detail image such that these details can be used to find the weights for image fusion using weighted average proposed in [12]. in this paper, the weights are computed by measuring the strength of details in a detail image obtained by applying the the images to be fused. the detail image, obtained by making the coefficient values of approximation band equal to zero then applying the inverse of counterlet transform, for image a and b to be fused. i unfocused area in image a will be focused in image b and the application of counterlet transform in such a manner on both images will capture the details which will be used to find the weights by measuring the strength of details. fig. 3 shows the block diagram of the proposed system. the block diagram of the proposed fusion system. make ll subbands of a,b equal to zero inverse discrete counterlet transform ����� � ����� � fused multifocus images a, b depending on wa, wb khwarizmi engineering journal, vol. 11, no. 3, p.p. 8595 (2015) the proposed algorithm in [13] the proposed image fusion algorithm directly fuses two source images of a same scene using weighted average. the proposed method other weighted average methods in terms of weight computation and the domain of weighted average. the weights are computed by measuring the strength of details in a detail image obtained by subtracting cross bilateral filter (cbf) output from original image. the weights thus computed are multiplied directly with the original source images followed by weight normalization. the idea is to capture most of the focused area details in detail image such that these details can be used to find the weights for image fusion using weighted average proposed in [12]. in this paper, the weights are computed by measuring the strength of details in a detail image counterlet transform to the images to be fused. the detail image, obtained he coefficient values of approximation band equal to zero then applying the inverse of counterlet transform, for image a in multifocus images, unfocused area in image a will be focused in image b and the application of counterlet rm in such a manner on both images will capture the details which will be used to find the weights by measuring the strength of details. fig. 3 shows the block diagram of the proposed wa wb find weights by measuring strength of details fused image iman m.g. alwan fig. 4 shows the details image obtained in the proposed algorithm with six numbers of levels for directional filter bank at each pyramid level. in order to show the power of counterlet transform in representing edges and other singularities along curves of images. wavelet transform (db2) is used to capture the details of the multifocuse images to be fused. fig. 5 shows the details i obtained by extracting the high frequency bands of the image through making the low frequency bands equal to zero in wavelet domain. one can notice that counterlet transform is more efficient in representing details than wavelet transform. fig. 4. multifocus clock source images in (a) and (b), details images in (c) and (d).using counterlet transform. fig. 5. multifocus clock source images in (a) and (b), details images in (c) and using wavelet transform. (a) (c) (a) (c) (d) (b) (d) (d) (b) al-khwarizmi engineering journal, vol. 11, no. 88 fig. 4 shows the details image obtained in the proposed algorithm with six numbers of levels for pyramid level. in order to show the power of counterlet transform in representing edges and other singularities along curves of images. wavelet transform (db2) is used to capture the details of the multifocuse images to be fused. fig. 5 shows the details image obtained by extracting the high frequency bands of the image through making the low frequency bands equal to zero in wavelet domain. one can notice that counterlet transform is more efficient in representing details than wavelet transform. 4. multifocus clock source images in (a) and (b), details images in (c) and (d).using counterlet 5. multifocus clock source images in (a) and (c) and using wavelet fusion rule proposed in [12] is adopted in [13] to compute the weights using statistical prosperities of a neighborhood of detail coefficient instead of wavelet coefficient. the fusion algorithm is also adopted in this pape the fusion algorithm a window of size around a detail coefficient considered as a neighborhood to compute its weight. this neighborhood is denoted as matrix x. every row of x is treated as an observation and column as a variable to compute unbiased estimate � ,� of its covariance matrix, where are the spatial coordinates of the detail coefficient ����, �� or ����, ��. ������������� � !�� " � ,� � ∑ �$%&$̅��$(&$ )� *+ %,�.&/� where, �( is the 0�� observation of the dimensional variable and mean. it is observed that, diagonal of matrix gives a variances vector for each column of matrix 1. now, the eigenvalues of matrix computed and the number of eigenvalues depends on size of � ,� . sum of these directly proportional to horizontal detail strength of the neighborhood and is denoted as 23�4��564���748 [12]. similarly, unbiased covariance estimate 9 ,� each 1 column as an observation and row as a variable (opposite to that of eigenvalues of 9 ,� gives vertical detail strength :3�4��564���748. that is, 23�4��564���748��, �� � :3�4��564���748��, �� � where ��7��( is the 0 unbiased estimate of covariance matrix. now the weight given to a particular detail coefficient is computed by adding these t strengths. therefore, the weight counts only on the details strength and not on actual intensity values. ;4��, �� � 23�4��564���74 :3�4��564���74 khwarizmi engineering journal, vol. 11, no. 3, p.p. 8595 (2015) fusion rule proposed in [12] is adopted in [13] to compute the weights using statistical prosperities of a neighborhood of detail coefficient instead of wavelet coefficient. the fusion algorithm is also adopted in this paper. in the fusion algorithm a window of size ; < ; around a detail coefficient ����, �� or �� (�, �� is considered as a neighborhood to compute its weight. this neighborhood is denoted as matrix x. every row of x is treated as an observation and column as a variable to compute unbiased of its covariance matrix, where �, � ial coordinates of the detail coefficient " !�=��� " !�=�� ... (1) ) ….(2) observation of the ; " dimensional variable and �̅ is the observations mean. it is observed that, diagonal of matrix � ,� gives a variances vector for each column of now, the eigenvalues of matrix � ,� is computed and the number of eigenvalues depends . sum of these eigenvalues is directly proportional to horizontal detail strength of the neighborhood and is denoted as [12]. similarly, unbiased is computed by treating column as an observation and row as a variable (opposite to that of � ,�), and the sum of gives vertical detail strength that is, � ∑ ��7��( . (>/ �? ca b,c ..(3) � ∑ ��7��( . (>/ �? cd b,c ..(4) 0�� eigenvalue of the unbiased estimate of covariance matrix. now the weight given to a particular detail coefficient is computed by adding these two respective detail strengths. therefore, the weight counts only on the details strength and not on actual intensity 23�4��564���748��, �� e :3�4��564���748��, �� … (5) iman m.g. alwan al-khwarizmi engineering journal, vol. 11, no. 3, p.p. 8595 (2015) 89 after computing the weights for all detail coefficients corresponding to both the registered source images, the weighted average of the source images will result in a fused image. if ;4� and ;4g are the weights for the detail coefficients �� and �� belonging to the respective source images � and �, then the weighted average of both is computed as the fused image using eq. 6 h��, �� = i� ,��.�j� ,��kl� ,��.�m� ,�� .�j� ,��k.�m� ,�� ... (6) 4. performance measures in most of the applications, the evaluation of fusion performance is a challenging task as the ground truth is not available. in the literature many metrics are presented to evaluate the performance of image fusion [17, 18]. these classical evaluation metrics are considered here for extensive study, which are as follows [12]: 1) average pixel intensity (api) or mean (f): an indicator of contrast. 2) average gradient (g): measure a degree of sharpness and clarity . 3) standard deviation (sd): this is the square root of the variance. it indicates data spread. 4) entropy (h): estimates the amount of information available in the image. 5) mutual information (mi) or fusion factor: quantifies the overall mutual information between source image and fused images. 6) fusion symmetry (fs) or information symmetry: an indication of how much symmetric the fused image is with respect to source images. 7) normalized correlation (corr): measures a relevance of fused image to source images. 8) petrovic metric parameter qopq : measures the overall transferred information from source images to fused one. 9) petrovic metric parameter lopq : measures edge information loss. 10) petrovic metric parameter silt : measures artifacts or noise added in fused image due to fusion process. equations 7 to 20 are used to compute (1-7) parameters, assuming image size of �u���. �vw = hx = ∑ ∑ �yz,[�\[,-]z,^$_ ...(7) ? ,� is pixel intensity for position (i ,j) of image f. 6` = a∑ ∑ �y� ,��&tx�b\[,-]z,^_ …(8) c̅ = ∑ ∑ ��yz,[&yzd-,[�bk�yz,[&yz,[d-�b�-/b[z ^$_ ... (9) �4��fg = −∑ f?�?�5�7hhiiy>j f?�?� …(10) where f?�?� is the probability of intensity value f in image f. kwit = ∑ ∑ f�, h��, ?�5�7h li,t��,y� li���lt���y� ...(11) kwlt = ∑ ∑ v�, h�m, ?�5�7h ll,t�g,y� ll�g�lt�y�yg ...(12) kwilt = kwit +kwlt ...(13) kwti = ∑ ∑ fi,t��, ?�5�7h no,p��,y� no���np�y�y� ...(14) kwlt = ∑ ∑ fl,t�m, ?�5�7hyg nq,p�g,y� nq�g�np�y �. ...(15) kwi,lt = kwit +kwlt ...(16) kwit is the mutual information between source image a and fused image b, while kwlt is the mutual information between source image b and fused image f.kwilt quantifies the overall mutual information measurement between source images and fused one. h6 = 2 − |kwit �kwit +kwlt� − 0.5⁄ | ...(17) �it = ∑ ∑ w��z,[�&i̅x�y�z,[�&tx�[z a��∑ ∑ ���z,[�[z &i̅�b�∑ ∑ �y�z,[�&tx�b�[z ...(18) �lt = ∑ ∑ wg�z,[�&lxx�y�z,[�&tx�[z a��∑ ∑ �g�z,[�[z &lx�b�∑ ∑ �y�z,[�&tx�b�[z ...(19) here �it and �lt represents normalized correlation between source image and fused image, the overall average normalized correlation can be calculated as: yzz = ��it + �lt�/2 ...(20) all the petrovic metrics, proposed by petrovic and xydeas [19], based on gradient information. this provides an in-depth analysis of fusion performance by quantifying: total fusion performance, fusion loss and fusion artifacts (artificial information created). a sobel edge iman m.g. alwan al-khwarizmi engineering journal, vol. 11, no. 3, p.p. 8595 (2015) 90 detector is used to compute orientation and strength information at each pixel in source and the fused images respectively. 5. the experimental results the experimental evaluation is performed on multi focus grey-scale and color images of size 256<256 pixels. in the counterlet transform, the lp filter is ‘pkva’ and dfb is ‘9-7’ type, and the number of directional filter bank decomposition levels at each pyramidal level (from coarse to fine scale), by experimental test, is six for optimum results, neighborhood window is 5x5 to find detail strength. fig. 6 displays the test multifocus grey scale images used and the resultant fused images, while fig. 7 displays the test multifocus color images used and the resultant fused images. book 1 desk 1 lena 1 clock 1 girl 1 book 2 desk 2 lena 2 clock 2 girl 2 fused book fused desk fused lena fused clock fused girl fig. 6. the multi focus test grey scale images, and resultant fused images. iman m.g. alwan al-khwarizmi engineering journal, vol. 11, no. 3, p.p. 8595 (2015) 91 ship 1 city1 container 1 cookies 1 books 1 ship 2 city 2 container 2 cookies2 books 2 fused ship fused city fused container fused cookies fused books fig. 7. the multi focus test color images, and resultant fused images. tables (1, 2) show the evaluation results of the outputted fused images for both grey scale and color images respectively. the evaluation of the proposed method is done by comparing with results obtained through using image fusion toolbox, kindly provided by kumar [13]. the quality of the fused images are better when these parameters have higher values, excluding {il/t , sil/t which should have lower values. in table (1), higher values are bolded except for {il/t , sil/t where lower values are bolded. table 1, performance comparison of test grey scale multifocus images. book api sd |) h mi fs corr }~�� �~�� �~�� proposed 84.3228 58.4854 12.2766 7.2700 9.0737 1.999 0.9918 0.986 0.014 1.6769e005 [13] 84.5140 59.4958 14.6905 7.2432 8.7287 1.998 0.9903 0.977 0.0232 2.7807e005 desk proposed 80.5457 67.5398 13.2131 7.2389 6.3178 1.971 0.9636 0.876 0.030 0.0034 [13] 81.3517 66.8859 13.2674 7.4217 6.1486 1.996 0.9643 0.885 0.113 0.0116 lena proposed 98.7034 51.4480 12.9027 7.5352 7.2215 1.983 0.9786 0.905 0.092 0.0345 [13] 98.8909 50.4837 12.7901 7.4998 6.6233 1.966 0.9791 0.907 0.091 0.0098 clock proposed 96.3000 49.7317 8.0268 7.2733 7.8923 1.973 0.9889 0.913 0.087 0.0047 [13] 96.5571 50.2380 9.0733 7.2972 7.8681 1.958 0.9876 0.908 0.091 0.0014 girl proposed 116.9926 50.9372 11.7083 7.5477 7.5616 1.995 0.9916 0.935 0.064 0.0037 [13] 117.5374 51.3023 14.7759 7.5751 7.4948 1.998 0.9876 0.941 0.057 0.0060 iman m.g. alwan al-khwarizmi engineering journal, vol. 11, no. 3, p.p. 8595 (2015) 92 table 2, performance comparison of test colored multifocus images. ship api sd |) h mi fs corr }~�� �~�� �~�� proposed 106.9133 48.443 8.7148 7.1714 8.1718 1.989 0.9886 0.889 0.109 0.0053 [13] 107.279 48.643 10.415 7.2026 8.2783 1.990 0.986 0.903 0.095 0.0085 city proposed 114.7009 47.4911 13.074 7.5148 8.3899 1.981 0.9830 0.912 0.086 0.0127 [13] 115.3971 56.3815 17.839 7.7572 8.8351 1.980 0.9808 0.916 0.081 0.0112 container proposed 168.9581 53.1473 9.0436 7.4530 7.1750 1.986 0.9715 0.906 0.089 0.0256 [13] 169.6191 53.9541 10.924 7.4819 7.3406 1.990 0.9698 0.914 0.080 0.0257 cookies proposed 143.345 59.450 15.923 7.8245 9.9503 2.000 0.9826 0.969 0.038 0.0019 [13] 143.898 59.436 17.372 7.8375 9.875 1.981 0.981 0.961 0.036 0.0098 books proposed 162.848 51.9838 13.171 7.2913 6.7079 1.946 0.9821 0.924 0.079 0.0012 [13] 163.517 51.6543 15.071 7.327 6.4308 1.951 0.9798 0.916 0.082 0.0037 from the results, we can notice that, the performance of the proposed method is slightly better than [13] in terms of overall mutual information between source images and fused image (mi), while for other performance measures, the proposed method is slightly better or less than proposed method in [13] in few tenths. also the proposed method was compared with methods in [5] where it is proposed to fuse multifocus images in the multiresolution dct domain with pixel level fusion rule, and [11], [12] for ‘book, desk’ images. table (3) shows the comparison results. table 3, performance comparison of proposed method and methods in [5, 11, 12]. book api sd |) h mi fs corr }~�� �~�� �~�� proposed 84.3228 58.4854 12.2766 7.2700 9.0737 1.999 0.9918 0.986 0.0143 1.6769e-005 [5] 85.1322 61.0523 11.7826 7.2996 7.3344 1.989 0.9821 0.885 0.1115 0.0033 [11] 84.7978 61.0248 11.7600 7.3045 7.0857 1.990 0.9819 0.884 0.1116 0.0045 [12] 85.4582 61.2135 11.8963 7.3141 7.2377 1.992 0.9821 0.880 0.1155 0.0045 desk api sd |) h mi fs corr }~�� �~�� �~�� proposed 80.5457 67.5398 13.2131 7.2389 6.3178 1.971 0.9636 0.899 0.030 0.0034 [5] 81.4877 64.6112 13.0945 7.5262 5.2655 1.991 0.9659 0.888 0.1064 0.0048 [11] 80.8079 64.3038 12.8823 7.4497 4.8638 1.947 0.9636 0.857 0.1328 0.0102 [12] 80.6225 64.0681 12.8277 7.4846 4.8645 1.980 0.9656 0.876 0.1157 0.0078 from the results, we can perceive that there is very small change in values of parameters. the proposed algorithm offer highest value for c̅ and mi, which means highest sharpness and clarity degree, and highest overall mutual information between source images and fused one respectively. it also clearly offers superiority with respect to petrovic metrics, it gives highest value for quality factor �ilt, and lowest values for loss of edge information {ilt and noise or artifacts added due to fusion silt. 6. conclusion in this paper, multifocus image fusion was proposed, it depends on using detail images extracted from the source images by applying counterlet transform, making approximation subband equal to zero, then applying applying inverse counterlet transform, the resultant image is the detail image only. weights are computed by measuring the strength of horizontal and vertical details, these weights are used to fuse the source images directly. the experimental results show that the proposed method offers iman m.g. alwan al-khwarizmi engineering journal, vol. 11, no. 3, p.p. 8595 (2015) 93 superior or similar performance as compared to other methods in terms of visual quality and quantitative parameters. it offers good performance over other fusion methods. notation api average pixel intensity ��� ,��,��� ,�� detail coefficients � ,�, 9 ,� unbiased covariance estimate cbf cross bilateral filter corr normalized correlation fs fusion symmetry g average gradient h entropy mi mutual information sd standard deviation �ilt , {ilt,silt petrovic metric parameters ;��,;�g weights of detail coefficients of images a, b respectively. 7. references [1] bedi, s. s., khandelwal, r. ,” comprehensive and comparative study of image fusion techniques”, international journal of soft computing and engineering, vol.3,no.1, pp. 300-304, march 2013. 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[7] wang,h., peng, j. and wu, w., ”fusion algorithm for multisensor images based on discrete multiwavelet transform”, ieee proceedings vision, image, and signal processing,vol.149,no.5, pp. 283– 289,2002. [8] dyla, m.h., tairi,h.,” multifocus image fusion scheme using a combination of nonsubsampled counterlet transform and an image decomposition model” journal of theoretical and applied information technology, vol.38 ,no.2 ,pp.136-144, april,2012. [9] cheng shangli, junmin, h., and zhongwei,l., ”medical image of pet/ct weighted fusion based on wavelet transform”, intnl. conf. on bioinformatics and biomedical engineering (icbbe), pp. 2523–2525, 2008. [10] shah, p., merchant, s.n., and desai, u.b., ”fusion of surveillance images in infrared and visible band using curvelet, wavelet and wavelet packet transform”, international journal of wavelets, multiresolution and information processing (ijwmip),vol. 8, no.2, pp. 271–292, 2010. [11] shah, p., srikanth, t.v., merchant, s.n., and desai, u.b., “a novel multifocus image fusion scheme based on pixel significance using wavelet transform”, ivmsp, pp. 54-59 ,2011. [12] shah, p., merchant, s.n., and desai, u.b.,” an efficient adaptive fusion scheme for multifocus images in wavelet domain using statistical properties of neighborhood”, 14th international conference on information fusion, ieee, pp.1-7, 2011. [13] kumar, b.k., ”image fusion based on pixel significance using cross bilateral filter”, signal, image and video processing ,springer, vol.7,no.5,september, 2013. [14] d. d.-y. po, do, m. n., “directional multiscale modeling of images using the contourlet transform,” ieee transactions on image processing, vol. 15, no. 6, pp. 1610–1620, 2006. [15] tamilarasi, m., palanisamy,v., “contourlet based medical image compression using improved ezw”, iman m.g. alwan al-khwarizmi engineering journal, vol. 11, no. 3, p.p. 8595 (2015) 94 international conference on advances in recent technologies in communication and computing, ieee computer society, pp. 800-804, 2009. [16] burt, p. j., and adelson, e. h., “the laplacian pyramid as a compact image code,” ieee transactions on communications, vol. 31, no. 4, pp. 532– 540, 1983. [17] v. petrovic, “multisensor pixel-level image fusion,” phd thesis, department of imaging science and biomedical engineering, manchester school of engineering, united kingdom, 2001. [18] kumar, b.k., “multifocus and multispectral image fusion based on pixel significance using discrete cosine harmonic wavelet transform,” j. sivip, 2012, doi: 10.1007/s11760-012-0361-x. [19] petrovic, v., xydeas, c., “objective image fusion performance characterisation”, proceedings of iccv’05, vol. 2, pp. 1866–1871 , 2005. )2015( 8595، ���� 3، ا�� د11 ا���ارز� ا��� �� ا������ � ا�� ن ���د ���ر 95 � و ������ �� counterletد�ا�,�ر �%� دة ا�%*(�) '$&#%�$د #�" أھ��� ا�� ��0* #��انإ��$ن ��� � �����ت/ ��� ���م ا������ت��� ا� ���$#اد/ !� �%&�' ainms_66@yahoo.com: ا���-# ا,�+ �و() ا����1 �a . (2 �ي ��? !< ا�5%��&�ت ا�5;5� &9 ا��3ر ا�5 %#دة إن ا�;#ف &9 د&8 ا��3ر ھ� �6 ا�5%��&�ت ذات ا��3� ��3ر & %#دة 2) �1رة وا/#ة 3� &9 ا�b �5ا� >�1�c 9 �1ر ا�& �;���g %�5ل أوزان � /�� h5# ��? ا���ب ا�5%#ل ا��5زون و ذ� %a 8&د �j-�اح ط�إ� �a ، nا ا���o�3ر ھ� ��-��a �5ل% ��� �;p&اد د�ا�35#ر ا�5counterlet .و��& q-�j ت ا�r&�%& >%' ?�� 9 ا��3ر ا�35#ر& >�1�c ص ا�rb إ� �j-�5# ط %a �c3�� � ��-��a س�+%& u��va �w 9&وcounterlet . 8&ق د�v��oھ� ��? ا�%#-# &9 ا��3ر & %#دة ا� �!�y و&�jر( ;� c� � �/� j5ا� �j-�v9 أداء ا�& uj� ا� �a . أ\�ى (microsoft word \307\315\343\317 \325\310\307\315 \346\344\346\3216473) al-khwarizmi engineering journal al-khwarizmi engineering journal,vol. 13, no. 3, p.p. 6473 (2017) a cognitive hybrid tuning control algorithm design for nonlinear path-tracking controller for wheeled mobile robot ahmed s. al-araji* noor q. yousif** *,**department of control and systems engineering/ university of technology *email:ahmedalaraji76@gmail.com (received 13 december 2016; accepted 7 march 2017) https://doi.org/10.22153/kej.2017.03.004 abstract this research presents a on-line cognitive tuning control algorithm for the nonlinear controller of path-tracking for dynamic wheeled mobile robot to stabilize and follow a continuous reference path with minimum tracking pose error. the goal of the proposed structure of a hybrid (bees-pso) algorithm is to find and tune the values of the control gains of the nonlinear (neural and back-stepping method) controllers as a simple on-line with fast tuning techniques in order to obtain the best torques actions of the wheels for the cart mobile robot from the proposed two controllers. simulation results (matlab package 2012a) show that the nonlinear neural controller with hybrid bees-pso cognitive algorithm is more accurate in terms of fast on-line finding and tuning parameters of the controller lead to obtaining smoothness with small spikes control action as well as minimizing tracking pose error of the wheeled mobile robot than the performance of nonlinear back-stepping technique. keywords: bees algorithm, nonlinear controller, matlab package, particle swarm optimization, wheeled mobile robots. 1. introduction in general, a wheeled mobile robot system considers a multi-input multi-output nonlinear dynamic and time variant system and the one of fundamental problems in the control engineering is the motion control design to track the desired path [1] because the mobile robot has many applications in various directions life such as: science; education; industry; entertainment; security and military therefore the mobile robot is still active region of research [2]. in the recent years, different types of control algorithms and controllers that they are based on mathematical model of the wheeled mobile robot and they are proposed to solve the motion control of the robot’s wheels in order to follow the desired trajectory with high performance of the controllers in terms of generating optimal action that lead to minimizing tracking pose error during tracking reference path, such as nonlinear neural pid controllers [3 and 4], fuzzy logic and pid controllers [5 and 6], neural networks controllers [7 and 8], back-stepping controllers [9 and 10], adaptive sliding mode controllers [11 and 12] and neural predictive controllers [13 and 14]. the motivation for this research is taken from [2, 3, 4 and 10] which are focusing on the problems of the mobile robot in terms of tracking and stabilizing the mobile robot on the desired path as well as how can generate best torque control action without saturation state and no spike action? the main core of the contribution of this research is described as follows: • using a different types of controllers with high computational accuracy that have been derived of the control laws in order to generate best torque action and lead to minimizing tracking pose error of the wheeled mobile robot. • cognitive hybrid bees-pso optimization algorithm proposed to show the ability in the fast search in local (pso) and global (bees) ahmed s. al-araji al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 6473 (2017) 65 regions in order to find and tune on-line the best parameters of the two types of controllers. • adding a dynamic disturbance to investigate the robustness performance of the proposed controllers. • changing the initial pose state to verify the adaptation performance of the proposed controllers. • tracking a variable radius continuous trajectory to validate the capability of the proposed controllers. the organization of this paper can be described as follows: in section two, is a description of the dynamic wheeled mobile robot model. section three is deriving the different types of the proposed nonlinear controllers. in section four, the proposed of a cognitive hybrid bees-pso optimization algorithms is explained. section five is presented the performance of the proposed controllers through simulation results. in section five, the conclusions are drawn. 2. model of a dynamic wheeled mobile robot fig.1 shows the schematic diagram of the cart wheeled mobile robot that it consists of a two dc motors which is driving the two wheels with one an omni-directional castor wheel that will stabilize the platform of the mobile robot [12 and 13]. the motion and orientation of the mobile robot depends on a two independent actuators (dc motors) for left and right wheels. r is the radius of the same of the two wheels and the distance between these wheels is l and c is the center of gravity of the mobile robot. fig. 1. mobile robot platform model. in general, the global coordinate frame is defined as [ ]yxo ,, while the pose vector of the mobile robot in the surface is defined as: tyxq ),,( θ= … (1) the position coordinates (x,y) are at point cwhile θ is orientation angle that is measured with respect to global frame in the x-axis therefore the configuration of mobile robot can be described by these three generalized coordinates. to investigate the motion and orientation of the wheeled mobile robot, two conditions should be achieved; the first is pure-rolling and the second is without-slipping in order to make the mobile robot’s lateral velocity is equal to zero as equation (2) [3 and 4]. 0)(cos)()(sin)( =+− •• ttyttx θθ …(2) then, the equations of the kinematics wheeled mobile robot in the world frame can be represented as follows [7 and 10]: )(cos) 2 )()(( )( t twltwrr tx θ + =& …(3) )(sin 2 ))()(( )( t twltwrr ty θ − =& …(4) l twltwrr t ))()(( )( − =θ& …(5) where wr(t) and wl(t) are the right and left angular velocities respectively. based on euler lagrange formulation [9 and13], the dynamic model of the mobile robot can be described as follows: λθ θ τ τ θθ θθ τ θ          − +                  − =+                       •• •• •• 0 cos sin 22 sinsin coscos 1 00 00 00 r l llr dy x i m m ..(6) where lτ is the torque of the left wheel. rτ is the torque of the right wheel. m is the mobile robot’s mass. i is the mobile robot’s inertia. λ is the constraint forces. dτ is bounded dynamic disturbances. the pose equations of the mobile robot in the simulation can be described as follows: ���� = ����� � ��� � …(7) � ��� = �.���������� ���� � …(8) ��������� = ���� � …(9) ��� ����� = ����� � …(10) ������� = ��������� × ∆! …(11) � ����� = ��� ����� × ∆! …(12) "#��� = �.�$%&�'(��� &�()����* � …(13) ahmed s. al-araji al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 6473 (2017) 66 "+��� = �.�$%&�'(����&�()����* � …(14) )1()(cos)]()([5.0)( −+∆+= kxtkkwlkwrrkx θ ...(15) )1()(sin)]()([5.0)( −+∆+= kytkkwlkwrrky θ ...(16) )1()]()([)( −+∆−= ktkwlkwr l r k θθ …(17) where � is total linear force; � is total angular torque; ������ is linear acceleration; ��� �� is angular acceleration; ���� is linear velocity; � �� is angular velocity; "+ is angular velocity of the left wheel; "# is angular velocity of the right wheel; )(),(),( kkykx θ are the pose of the mobile robot at each step kth of the movement and t∆ is the sampling time. 3. nonlinear controller methodology in general, a feedback control signal based on different types of the nonlinear controllers are very important in the structure of the proposed controller in terms of stabilizing and minimizing the tracking pose error of the wheeled mobile robot during the mobile robot’s pose is drifted from the reference path. block diagram of the proposed structure of the nonlinear trajectory tracking controllers for wheeled mobile robot can be shown in fig. 2. the first structure of the nonlinear controller equation is neural network that it performed as a nonlinear pid controller [3 and 4]. the nonlinear neural control structure has strong of adaptation performance, high dynamic characteristic and good robustness performance because the proposed structure is built on a traditional pid controller and employed the theory of the neural network technique. the structure of the proposed nonlinear neural controller can be shown in fig. 3. the proposed control law of the nonlinear neural controller for the right and left torques as follows: yxrr obobkbk 12111 )1()( ++−= ττ (18) θττ obobkbk yll 141315 )1()( ++−= …(19) the outputs yx oo , and θo of the neural networks. sigmoid function is used as nonlinear relationship as equation (20) [3 and 4]: 1 1 2 − + = − γ γ net e o …(20) where .,, θγ yx= γnet is calculated from these equations: )]1()([)]([)( 32 −++= kekebkebknet xxxx )]1()([4 −−+ kekeb xx …(21) )]1()([)]([)( 65 −++= kekebkebknet yyyy )]1()([7 −−+ kekeb yy …(22) )]1()([)]([)( 98 −++= kekebkebknet θθθθ )]1()([10 −−+ kekeb θθ …(23) where )(keγ is the input error signal. the control parameters b1, b2, … and b15 are on-line updated by using cognitive hybrid beespso optimization algorithm. fig. 2. the proposed structure of nonlinear trajectory tracking controllers for mobile robot. nonlinear controller equations cognitive hybrid beespso algorithm )2( )1( )( − − ke ke ke γ γ γ       )( )( k k l r τ τ + dynamic disturbances [ ])1()1( −− kk lr ττ ∆ )1( )1( )1( + + + k ky kx θ rotation matrix )1( )1( )1( + + + k ky kx r r r θ reference velocities eqs. parameters ahmed s. al-araji al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 6473 (2017) 67 fig. 3. the structure of nonlinear neural controller [3 and 4]. the second structure of the nonlinear controller equation is back-stepping technique based on lyapounov method [10]. the nonlinear back-steeping controller method structure can be shown in fig. 4. based on back-stepping technique in [9 and 10], the nonlinear angular velocity control law can be described by eq. (24) and applying the proposed hybrid bees-pso tuning algorithm for finding and tuning the best value of the parameters (b1, b2 and b3) then solving equations (7 to 14) to find the right and left torques control action for wheeled mobile robot.                 ++−+ ++++ =      r evbevbw l ebev r evbevbw l ebev w w ryrrxr ryrrxr l r ))sin( 2 cos( ))sin( 2 cos( 321 321 θθ θθ (24) 4. cognitive hybrid bees-pso algorithm the purpose of the on-line cognitive hybrid bees-pso algorithm is to find and tune the optimal gains control for the proposed controller to generate the best and smoothness torque signal that will lead to minimizing the tracking pose error of the wheeled mobile robot during dynamic disturbance has been added. in general, bees algorithm mimics the food foraging behavior of swarms of honey bees and this algorithm carries out by using local (neighborhood) search that has two types of bees (selected and recruit bees) and global (random) search that has also two types of bess (scout and fittest bees) [15 and 16] while the particle swarm optimization (pso) is considered one of the algorithms types that has a capability to search for the optimal solution by simulating the movement and flocking of birds. in pso algorithm, the particles that have a position and velocity are a population of individual in order to move around the search space to find best or optimal solution through evaluation each particle by using a fitness function [3 and 4]. 4.1. hybrid bee-pso (hbpso) algorithm in this work, the proposed on-line optimization algorithm is a hybrid tuning control algorithm which consists of bees algorithm [15 and 16] and pso algorithm [3 and 4]. the main advantages for this proposed optimization algorithm are to solve the problem of local search of the bees algorithm using pso algorithm which has the high ability for local search through generating population (recruit bees) as particles and this will speed up the process of optimization while the problem of the global search in the pso algorithm is solved by using bees algorithm which has the capability of combining the (fittest bees) and a new population of (scout bees) generating in the global search. the proposed on-line hbpso algorithm is applied as a powerful optimization algorithm to h )(ke x + )(krτ )1( −krτ ox + + +1 +1 + +1 )1( −ke x b1 h )(key oy + + +1 +1 +1 -1 + +1 )1( −key h )(keθ + )(klτ )1( −klτ o + + -1 +1 +1 +1 + +1 -1 )1( −keθ -1 +1 b15 b11 b12 b13 b14 b2 b3 b4 b5 b6 b7 b8 b9 b10 fig. 4. the nonlinear back stepping controller structure [10]. ),,,,,( 3,2,1blrwvqfv rrecc =           θe ey ex [ ] 321 bbb [ ]rr wv       l r w w t velocity ∂ ∂ [ ]lr       ang lin acc acc ( )im       l r τ τ ahmed s. al-araji al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 6473 (2017) 68 find and tune the optimal stable parameters of the nonlinear neural controller in order to enhance the performance characteristics of the system by reducing the processing time as well as improve the response accuracy through minimizing the tracking error for mobile robot. the proposed hbpso algorithm’s steps can be described as follows: 1. scout bees (n) are generated in the global (random) search as the initial population with randomly fifteen values of the controller’s parameters in the nonlinear neural controller while only three control parameters in the nonlinear back-stepping controller. 2. calculated the fitness of the (n) scout bees by using the fitness equation (25) [3] based cost function. -.!/011 = 2 3 4567 �8�97�5� ...(25) where: : > 0 to avoid division by zero. the proposed cost function is a mean square error as equation (26). =>? = 2 @ ∑ ��b�cd − b�%+�g�cd − g�%�h�cd − h�%@ �i2 + ��+./�cd − �+./�% + �j�cd − j�%� …(26) k: is the number of iteration. 3. in the local search, chosen the number of particles depends on the number of the highest fitness for the scout bees (population) as (m) selected bees. 4. the size of (patch size) of the local search is determined by applying the proposed equations (27). ∆l̅ = 0.025 × l̅5pq × #r/stu�0,1� …(27) l̅�cx = l̅5pq + ∆l̅ …(28) where l̅ : is the vector of the fifteen parameters of the proposed controller. 5. particles are generated by using equations (28) to search and find the best controller’s parameters. 6. evaluated the proposed cost function of each particle using the mean square error equation (26). 7. set to pbest for each particle in the current searching point. when the search is finding the best value of pbest then sets the pbest to gbest and store the number of the particle with the best value. 8. the pbest value is replaced by the current value if the value is better than the current pbest of the particle and if the best value of pbest is better than the current gbest, gbest is replaced by the best value and the particle number with the best value is stored. 9. each particle is update by using eqs. (29 and 30). )()( )()( 22 )()( 11 )()1( k m kk m k m k m k m bgbestrcbpbestrcbb −+−+ω∆=∆ + … (29) )1()()1( ++ ∆+= k m k m k m bbb …(30) where popm ,.....3,2,1= ; )(k mb is the particle’s weight m at kth iteration;ω : is the inertia weight factor; c1 and c2 are the positive values ; r1 and r2 are random numbers between 0 and 1; m pbest is best previous weight of mth ;particle and gbest is best particle among all the particle in the population. 10. return to step six if the current iteration number did not reach to the predefined maximum iteration number otherwise pick out the highest fitness for the particles as fittest bees (m). 11. return to global search by assign the (n-m) remaining bees to random search and generating a new population of scout bees. in general, the steps of the on-line cognitive hybrid bees-pso optimization algorithm for finding and tuning control parameters are repeated at 0.1 second (sampling time) for each kth sample based on shannon theorem. 5. simulation results matlab package used to verify the proposed nonlinear controllers of the trajectory tracking for the dynamic model of the wheeled mobile robot. the eddie mobile robot platform specifications are picked from [17]: m=12kg is the mobile robot’s mass; i=1.536kg.m2 is the mobile robot’s inertia; r=0.075m is the radius of wheel and l=0.39m is the distance between wheels. the matlab simulation is carried out online cognitive tuning control algorithm with proposed controllers as shown in figure (2) to track a reference pose with continuous variable radius path and 0.1 sec is sampling time. in this paper, two types of the nonlinear controllers are used (neural network and back-stepping technique) with hybrid bees-pso tuning control parameters to show which of them is batter in term of generating optimal and smoothness torque control action and minimizing the tracking error with minimum number of iteration. the parameters of the optimization hybrid bees-pso algorithm that will define as follows: the scout bees (n) is equal to 10 at the global search; the selected bees is equal to 5; the particle is equal to 40 in the local search; the fittest bees ahmed s. al-araji al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 6473 (2017) 69 is equal to 5; the iteration number (n) in the global search is equal to 3and the iteration number (p) in the local search is equal to 3. case study the reference pose trajectory for wheeled mobile robot can be described in below equations (31, 32 and 33): ) 20 2 sin()( t txr π = …(31) ) 40 2 sin()( t tyr π = …(32) ) )())(())(( )( (tan2)( 22 1 txtytx ty t rrr r r ∆+∆−∆ ∆ = −θ … (33) the mobile robot has initial pose as ]4/,0,1.0[)0( π−=q . after applying the structure of the cognitive hybrid bees-pso tuning control algorithm with two different types of the nonlinear controllers and adding small values of the dynamic disturbances as the term that taken from [14] [ ]tttd )2sin(01.0)2sin(01.0=τ to show the controller ability of robustness through the online adaptation the parameters of these controllers. the trajectory tracking for mobile robot model can be shown in fig. 5 which it is clearly, the excellent tracking performance depends on mse of the mobile robot pose when was applying the nonlinear neural controller than nonlinear backstepping controller because the cognitive hybrid bees-pso tuning control algorithm was found and tuned fifteen parameters of the nonlinear neural controller that covered the nonlinear operation regions while in the nonlinear back-stepping controller has three parameters only and could not cover these regions especially when adding a bounded dynamic disturbances. this proposed control algorithm has a capability of perfect search in two search space (local and global) with minimum number of iteration in both search space. fig. 5. the desired and actual trajectory for mobile robot. in fig. 6 demonstrates the orientation tracking performance of the mobile robot with two types of controllers. fig. 6. the desired and actual orientation for mobile robot. in this on-line tuning control algorithm, the proposed mean square error (mse) clearly improved the performance of these controllers by showing the pose error convergence for the mobile robot motion at 200 steps, as shown in figs. 7 and 8. -1.2 -1 -0.5 0 0.5 1 1.2 -1.2 -0.5 0 0.5 1.2 x-axis (meter) y -a x is ( m e te r ) actual path based back stepping actual path based neural desired path 20 40 60 80 100 120 140 160 180 200 -4 -3 -2 -1 0 1 2 3 4 samples (sampling time 0.1 sec) o r ie n ta ti o n ( r a d ) orientation based back -stepping orientation based neural desried orientation ahmed s. al-araji al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 6473 (2017) 70 fig. 7. on-line performance index for nonlinear neural controller. fig. 8. on-line performance index for nonlinear back-stepping controller. fig. 9 shows the effectiveness of the nonlinear neural controller response through generating best torque control action without saturation control action state to track the desired path in minimum time while the torque control action for the nonlinear back-stepping controller can be shown in fig. 10 which has non smoothens and not high spikes and reach to the maximum saturation torque action value in data sheet of motor [17] is 3 n.m only at starting and for very short time. fig. 9. torque control action for nonlinear neural controller. fig. 10. torque control action for nonlinear backstepping controller. the response of angular velocity of the left and right wheels of the platform eddie wheeled mobile robot can be shown in fig. 11 have smoothness response which are generated from nonlinear neural controller while the angular velocities of the left and right as shown in fig. 12 have small spikes response that are generated from the nonlinear back-stepping controller. it is clear, that the response between (60 to 80) samples and between (120 to 140) samples of the torque and angular velocity as shown in figs. 9 and 11 respectively are non-smooth and have spikes because in this region the orientation in fig. 6 is changing between -180o to 180o that needs to add 2pi for correcting the orientation and this big change will lead to small spikes and nonsmooth response in this region. figs. 13-a,b,c show the robustness and adaptation performance of the proposed controller in terms of keeping on minimum tracking pose error for the wheeled mobile robot and stabilizing the pose of the mobile robot when the mobile robot tries to drift from the desired path because the effect of the bounded dynamic disturbances to the system. fig. 11. angular velocities of the left and right wheels for nonlinear neural controller. 20 40 60 80 100 120 140 160 180 200 0 0.005 0.01 0.015 0.02 0.025 samples (sampling time 0.1 sec) p e r fo r m a n c e in d e x ( m s e ) 20 40 60 80 100 120 140 160 180 200 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 samples (sampling time 0.1 sec) p e rf o r m a n ce i n d e x ( m s e ) 20 40 60 80 100 120 140 160 180 200 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 2.5 samples (sampling time 0.1 sec) l e ft a n d r ig h t t o rq u e c o n tr o l a ct io n ( n .m ) the torque of left wheel the torque of right wheel 20 40 60 80 100 120 140 160 180 200 -4 -3 -2 -1 0 1 2 3 4 samples (sampling time 0.1 sec) l ef t a n d r ig h t t o r q u e c o n tr o l a c ti o n ( n .m ) the torque of right wheel the torque of left wheel 20 40 60 80 100 120 140 160 180 200 -2 0 2 4 6 8 10 12 l e ft a n d r ig h t w h e e l a n g u la r v e lo c it y ( r a d /s ec ) the angular velocity of left wheel the angular velocity of right wheel ahmed s. al-araji al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 6473 (2017) 71 fig. 12. angular velocities of the left and right wheels for nonlinear back-stepping controller. fig. 13. pose error of the mobile robot: a) error in x-axis; b) error in y-axis; c) orientation error. 6. conclusions the simulation results on the on-line cognitive hybrid bees-pso tuning algorithm of different types of nonlinear controllers are presented in this paper for the dynamic wheeled mobile robot model which shows preciously and that the proposed hybrid bees-pso tuning control algorithm was better than the results in [3 and 4] in terms of the following capabilities: • fast and stable on-line finding and tuning the parameters of the controller with minimum number of iteration in the local and global search. • obtaining best torque control action, with small spikes as well as no saturation torque action state for the nonlinear neural controller. • minimizing the pose error and no oscillation output for the wheeled mobile robot during motion in the reference path. • strong adaptability and robustness performance when dynamic disturbances have been added to the mobile robot. 7. references [1] leenaa n. and sajub k.k., modelling and trajectory tracking of wheeled mobile robots. international conference on emerging trends in engineering, science and technology (icetest 2015), vol. 24, pages 538–545. 2016. [2] asif m., khan m. j., rehan m. and safwan, m., feedforward and feedback kinematics controller for wheeled mobile robot trajectory tracking. journal of automation and control engineering, vol. 3, no.3, pp.178–182. 2015. [3] ahmed al-araji, comparative study of various intelligent algorithms based nonlinear pid neural trajectory tracking controller for the differential wheeled mobile robot model. journal of engineering vol. 20, no. 5, pp. 44-60. 2014 [4] khulood e. dagher and ahmed al-araji, design of a nonlinear pid neural trajectory tracking controller for mobile robot based on optimization algorithm. engineering & technology journal. vol. 32, no. 4, pp 973986. 2014. [5] safwan m., uddin v. and asif m., nonholonomic mobile robot trajectory tracking using hybrid controller, mehran university research journal of engineering and technology, vol. 35, no. 2, 2016. [6] martinez-soto r., castillo o., aguilar l. and baruch, i, bio-inspired optimization of fuzzy logic controllers for autonomous mobile robots, fuzzy information processing society (nafips-2012), annual meeting of the north american, pp. 1–6, 2012. 20 40 60 80 100 120 140 160 180 200 -2 0 2 4 6 8 10 12 samples (sampling time 0.1 sec) l e ft a n d r ig h w h e el a n g u la r v e lo c it y ( r a d /s e c ) the angular velocity of left wheel the angular velocity of right wheel 20 40 60 80 100 120 140 160 180 200 -0.2 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 samples (sampling time 0.1 sec) 20 40 60 80 100 120 140 160 180 200 0 0.5 1 1.5 samples (sampling time 0.1 sec) 20 40 60 80 100 120 140 160 180 200 0 0.2 0.4 0.6 0.8 1 1.2 samples (sampling time 0.1 sec) ahmed s. al-araji al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 6473 (2017) 72 [7] abdallan ty and hamzah mi, trajectory tracking control for mobile robot using wavelet network, international journal of computer applications, vol. 74, no. 3, pp. 327, 2013. [8] ye j., tracking control for nonholonomic mobile robots: integrating the analog neural network into the backstepping technique, neurocomputing, vol. 71, no. 16–18, pp. 3373–3378, 2008. [9] hou z.-g, zou a.-m., cheng l. and tan m., adaptive control of an electrically driven nonholonomic mobile robot via backstepping and fuzzy approach, ieee transactions on control systems technology, vol.17, no.4,pp. 803–815, 2009. [10] ahmed al-araji, development of kinematic path-tracking controller design for real mobile robot via back-stepping slice genetic robust algorithm technique. arabian journal for science and engineering 39 (12), 8825-8835, 2014. [11] koubaa y., boukattaya m. and dammak t., adaptive sliding-mode dynamic control for path tracking of nonholonomic wheeled mobile robot. journal of automation and systems engineering vol. 9,no. 2, pp. 119131, 2015. [12] aicha b., atallah b.1 and farès b., integral sliding mode control for trajectory tracking of wheeled mobile robot in presence of uncertainties, journal of control science and engineering, vol.2016, article id 7915375, 2016. [13] ahmed al-araji, maysam abbod, and hamed al-raweshidy, neural autopilot predictive controller for nonholonomic wheeled mobile robot based on a pre-assigned posture identifier in the presence of disturbances. 2nd international conference on control, instrumentation and automation (iccia),pp. 326-331, 2011. [14] ahmed s. al-araji, maysam f. abbod and hamed s. al-raweshidy, design of a neural predictive controller for nonholonomic mobile robot based on posture identifier, proceedings of the iasted international conference intelligent systems and control (isc). cambridge, united kingdom, july 11 13, 2011, pp. 198-207, 2011. [15] d.t. pham, a. ghanbarzadeh, e. koc, s. otri, s. rahim and m . zaidi, the bees algorithm. technical note, manufacturing engineering centre, cardiff university, uk, 2005. [16] d.t. pham, e. kog, a. ghanbarzadeh, s. otri, s. rahim, m. zaidi, the bees algorithm – a novel tool for complex optimisation problems, iproms 2006 proceeding 2nd international virtual conference on intelligent production machines and systems, oxford, elsevier, 2006. [17] internet websitehttp://parallax.com/. robotics with the eddie mobile robot text manual. accessed sept. 2016. )2017( 64-73، صفحة 3د، العد13دجلة الخوارزمي الهندسية المجلم احمد صباح االعرجي 73 خوارزمية هجينة مدركة لتنغيم مسيطر الخطي لتتابع مسار لعجلة اإلنسان آلي متنقل تصميم **نور قاسم يوسف *أحمد صباح االعرجي الجامعة التكنولوجية /قسم هندسة السيطرة والنظم**،* ahmedalaraji76@gmail.com:البريد االلكتروني* الخالصة بشكل حي ومتصل للمسيطر الالخطي لتتابع مسار عجلة اإلنسان اآللي الحركي لتباع المسار ان هذا البحث يقدم خوارزمية تنغيم المسيطر المدركة يطر (العصبي المستمر المرغوب.ان الهيكلية المقترحة لخوارزمية االمثلية هي الهجينة (النحل مع حشد الجسيمات االمثلية) اليجاد وتنغم قيم كسب المس وبساطة تقنية التنغيم وبشكل حي ومتصل.وطريقة الخطوة الراجعة) وتتميز بسرعة لقد تم إثبات من ان افضل عزم مسيطر لعجلة اليمين واليسار لعربة اإلنسان اآللي تم توليدها بشكل حي ومتصل من خالل المسيطرين المقترحين. ر دقة من حيث ايجاد وتنغيم عناصر المسيطر بشكل خالل نتائج المحاكاة أن المسيطر العصبي الالخطي المقترح مع الخوارزمية الهجينة المدركة هي اكث تقليل الخطأ ألتتابعي لعجلة اإلنسان اآللي مقارنة مع أداء المسيطرة ذات تقنية الخطوة فضالعنحي ومتصل ويؤدي الى الحصول على فعل سيطرة ناعم الراجعة. <4d6963726f736f667420576f7264202d2037312d3831d5c7cfde20e6c7cde3cf20e6d1ddeddd> al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 14, no. 2, june, (2018) p.p. 71-81 investigation microwave furnace effects on mechanical properties and fatigue life of aa 7075-t73 with dry and acid treatments sadiq jaffer aziz* ahmed adnan al-qisy** rafeef jumaa salman*** *,**,***department of mechanical engineering/ university of technology *email: s-j-aziz@hotmail.com ** email: abomrem2004@gmail.com *** email: rafef1362@gmail.com (received 4 june 2017; accepted 31 october 2017) https://doi.org/10.22153/kej.2018.10.001 abstract microwave heating is caused by the ability of the materials to absorb microwave energy and convert it to heat. the aim of this study is to know the difference that will occur when heat treating the high strength aluminum alloys aa7075-t73 in a microwave furnace within different mediums (dry and acidic solution) at different times (30 and 60) minutes, on mechanical properties and fatigue life. the experimental results of microwave furnace heat energy showed that there were variations in the mechanical properties (ultimate stress, yielding stress, fatigue strength, fatigue life and hardness) with the variation in mediums and duration times when compared with samples without treatment . the ultimate stress, yielding stress and fatigue strength decreased for all states compared with standard values. with reference to fatigue life, the results showed that the increment in fatigue life occurred for test states of dry 60 minutes in a microwave furnace, which were only 25%. moreover, the increment in hardness range was reached for test state of acid in 60 minutes which was about 7.3%, and 5 % for dry in 30 minutes and only 3%. keywords: aluminum alloy, fatigue life, heat treatment, mechanical properties, microwave furnace. 1. introduction microwaves had been part of the electromagnetic spectrum with frequencies ranging from 300 mhz to 300 ghz and consistent wavelengths between 1 m and 1 mm respectively [1,2]. however,2.45 ghz and 915 mhz were the commonly-using microwave frequencies for study and industrial actions [3,4]. heat generated from within the body by the absorption of microwave furnace heat energy (mfhe) directly by the body and does not need substantial heating of the environment. therefore, a temperature gradient exists in both conventional and mfhe as a result of the way heat is transferred /generated in the object [1]. microwave furnace heat energy processing’s are a green manufacturing process, significantly fast and hence tends to be highly economical. mfhe had been effectively and efficiently using for processing of ceramics and composite materials which are else hard to process through conventional processes [1,6], its fine microstructures and improved mechanical properties are observed with reduced processing duration time [6]. when a material absorbs mfhe, heat can be generated inside the material and heating was instantaneous generated with the introduction of power [1, 2]. another advantage of microwave furnace heating was that it could accelerated reaction rates and reduces reaction temperatures by reducing activation energy [2]. microwave material processing technology had sadiq jaffer aziz al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 7181 (2018) 72 been gaining much interest due to the relatively low manufacturing costs, energy and time saving, the fast sintering process, short soaking time, higher energy efficiency, improved product uniformity and high yields [3]. there are number of reports related with microwave oven heating of metals in various fields: sintering, joining, metal glass and composite materials [5]. also, it used to reduce metal oxides to their metallic forms may product in problems connected with microwave communication with molten metals [2]. in microwave furnace heat processing, mfhe heats the alloy at the varies heat levels, which will might leads to a uniformly bulk heating, conversely in the conventional heating systems, the alloy heated from inner core to the surface which produces thermal stress and/or longer time required for homogenization [1]. the fracture strength, toughness and hardness arrived from microwave furnace energy of treated specimen components were reported to be higher than others conventionally heat-treated application ones [6,7]. a heat-treating process by microwave furnace can be used for a wide application of surface treatments such as carbonating, carburizing, bronzing and chroming [8,9]. in this work, a newer technique including microwave furnace post heat treatment of sample surface were employed. period microwave furnace was used efficiently to process aa7075t73. the research concentrated on the mechanical properties and estimated fatigue life affected by the microwave furnace energy heat treatment of the alloy used. in this work, the sheet material was heat treated using microwave furnace energy at 2450mhz and 900w and the estimated fatigue life as long as its effect on mechanical properties is discussed in this work in details. 2. experimental work 2.1 material selection 7xxx series aluminum alloys have been widely used as structural materials in aeronautical industries due to their attractive comprehensive properties, such as low density, high strength, ductility, toughness and resistance to fatigue [10], also it attracting much attention because of their favorable strength-to-weight ratio and corrosion resistance compared to conventional stainless steels[11,12].the 7xxx-series alloys have zinc as their primary alloying agent, with a small amount of magnesium added. some alloys also contain copper or chromium [13]. it is general known that aluminum alloy 7075-t73 has high strength and relatively a very good resistance for corrosive [12]. the chemical composition of aa 7075-t73 shown in table 1, the tests were conducted at the cosqc-baghdad (central organization for standardization and quality control) according to the isq (iraqis specification quality) 1473/1989 by the device (spectrometer, arc. met 8000, 2009). the standard properties are given with the actual results in table 2. table 1, chemical composition of the aluminum alloys [astm] table 2, mechanical properties of aa 7075-t73 as taken from the sier and/or cosqc 2.2. specimen preparation aa7075-t73 plat with thickness (3mm) formed to a standard test specimen (tensile, fatigue life). the sample profile was obtained using a cnc milling machine with a special fixture to achieve specimen geometry accordance with the standard [astm e9m]. sample must be personnel and accurately calibrated as long as the tensile machines and this is very important before applying the test. preparation the specimen maybe concludes: grinding and polishing the samples. compo nent % si % fe % cu % mn % mg stand. astm ≤0.4 ≤0.5 1.22.0 ≤ 0.3 2.1-2.9 used 0.28 0.26 1.51 0.21 2.24 compo nent % cr % zn % ti % other % al stand. astm 0.180.28 5.16.1 ≤0.2 ≤0.15 rem. used 0.265 5.18 0.03 0.098 rem. mechanical properties 7075-t73 hardness value rockwell b 89.5 ultimate tensile strength 496 mpa tensile yield strength 385 mpa elongation at break 18 % modulus of elasticity 76.3 gpa fatigue strength 223 mpa suface roughness 0.6 sadiq jaffer aziz al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 7181 (2018) 73 2.3. process parameters in this work the specimen was mounted into the microwave furnace type (lifetec mikrowelle 2450 mhz,900w) as shown in fig.1, the specimens were installed in baker filled with 1 liter of acidic mediums (organic vinegar, acidity 4-6 %). two-time interval was selected, 30 min. and 60 min. respectively. the reason to selecting such interval time is from formal research [7]. the mean idea is to estimate the effects of thermal energy arrived by the heat weaves of microwaves furnace. then the samples were left to be cooled slowly inside the microwave furnace. for another test, the samples were placed inside the microwave in dry medium also treated in microwave furnace at different time (30 and 60 min). fig. 1. microwave furnace with sample. 2.4. mechanical testes 2.4.1. tensile test [astm b557m 15] the tensile test was carried out according to american society for testing material (astm) [14]. the geometry and dimensions of the plate tensile samples were shown in figs.2 and 3. the tensile test was done using (50kn tinus olsen) testing machine. the average value of three tests is recorded and used to draw the stress-strain curve. the selected sample for such tests must conform to exact physical dimensions and it must be free of heat distortion or induced cold working. fig. 2. standard tensile test sample, all dim. in mm for plane specimen [astm e9m]. fig. 3. tensile test machine 2.4.2. fatigue life test [avery plane bending fatigue test machine] in this research, a fully reversed reciprocating plane bending fatigue testing machine type avery denison-7305, was used to carry out the fatigue testing. the tests were undertaken in stress controlled with a stress ratio r= -1 and the cycling rate is 1400 rpm (f=23.6 hz). the machine is provided with a cycle counter. this cycle counter records the number of cycles in multiples of thousands as shown in figs.4 and 5. fig. 4. standard fatigue test sample with thickness of 3mm all dim. in mm for plane sample [avery manual]. computer & software sample jaws printer sadiq jaffer aziz al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 7181 (2018) 74 fig. 5. plane bending fatigue testing machine type avery model 7305 1. mechanical counter 2. motor 3. sample fixture 4. digital counter 5. clamp 6. fixed grip 7. the sample 8. movable 2.4.3. hardness test hardness is the property of a material that enables it to resist plastic deformation, usually by penetration. however, the term hardness may also refer to resistance to bending, abrasion, scratching or cutting. test [astm e110 14] was done by (rockwell hardness testing machine). fig.6. the rockwell hardness test method consists of indenting the test material with a diamond cone or hardened steel ball indenter. the samples were polished and mounted on the machine using a dwell time of 15 seconds. the depth of penetration was measured using the rockwell hardness number was calculated. fig. 6. rockwell hardness testing machine 2.4.4. surface roughness tests roughness an important part in computing how a real thing will interaction with its surrounding. in tribology, rough surfaces samples usually wear more quickly and have friction coefficients higher than smooth surfaces. roughness is often a good predictor of the performance of a mechanical component, since irregularities on the surface may form nucleation sites for cracks or corrosion. on the other hand, roughness may promote adhesion. the test was done by (pocket surf iv surface roughness testing machine fig.7). fig. 7. pocket surf iv surface roughness testing machine. 2.4.5. microstructure and surface topographic image to study the microwave furnace heat energy behavior of aa7075-t73, light microscope images were taken for different regions in the samples surface, where samples prepared with (1*1cm2) selection, mounting, grinding, polishing and etching. the microstructures then characterized by light microscopy fig.8, after etched by using killer solution (2.5 ml hno3, 1.5 ml, hcl,1 ml hf, 95 ml h2o). fig. 8 . light microscope test. test tool sample digital screen light microscope sample computer & software sadiq jaffer aziz al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 7181 (2018) 75 3. experimental results first, the temperature was measured from experimental works, for each medium as shown in table (3) below. however, table (4) shows the mechanical properties, of the results that have been calculated after the four tests processes. table 3, temperatures of mediums 1. the ultimate tensile stress, which reduced in all groups compared with standard values. where maximum reduction of 31.8 % was for dry at testing time 60 min in a microwave furnace groups, 15 % for dry 30 min in a microwave furnace. there were less of 2.8 % for test group of acid 60 min. also, 2 % decrement for dry 30 min group. 2. also, found that decreasing the yielding with decrements in extension percentage too, where a little effect for tests group of acid 30 and 60 min in microwave furnace of about 2% and 2.8% only, while for dry 30 and dry 60 group tests of 15% and 31.8% respectively. fig.9. 3. elongation at break, the calculated results indicated that the alloys brittleness is increased due to the excessive heat from the microwaves furnace with respect to duration time, which is made some changes in phases of the alloys surfaces leads the gran size of both alloys to decrease figs. 11-13. the extension of these alloys is decreased generally from references due to the same reasons above but the major decrement was for the test group of dry 60 min in microwave furnace of about 37% and about 22% for test group of acid 60 min in microwave furnace than reference, while there was decrement of about 25% for test group of dry 30 min in microwave furnace and only 11% for the last group all than its references. 4. it is also noticed that, for the fatigue strength test group of dry 60 min in microwave furnace was decreased its value of about 31.8% lower than references, while for test group of dry 30 min in microwave furnace there was decrement of about 15%. but in acid 30 and 60 min in middle test shows very little effect 2% and 2.8% respectively, decrement percentage. 5. there was not a great noticed change in the modulus of elasticity for all tests groups 6. hardness, it has been noticed that the higher value was for test group of acid60 min in microwave furnace with increment of about 7.3% and 5 %for dry 30 from standard without treatment samples, while the decrement in hardness were for dry 60 only about 8.4% and 4% for acid 30 table (4). 7. surface roughness, noticed that when time increasing the temperature increasing and the surface roughness increase. the majority effects were at (60 and 30) min with acidic mediums (133%and 66%) respectively, that because of corrosion occurred on the surface of the sample led to initiation pits which increase surface roughness with increase duration time as shown in fig.12, 40% increment was occurred for dry 60 min group figure. showed that, while the effect was occurring at dry 30 min tests only about 21.7%. state temperature (°c) 30 min 60 min dry 133 145 acid 70 75 sadiq jaffer aziz al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 7181 (2018) 76 table 4, mechanical properties of aa 7075-t73 have been calculated of the four groups. table 5, mathematically represent of basquin equation (amplitude stress) σa mpa fig. 9. stress-strain chart for tensile test. fig. 10. s – n curves for all the fatigue tests samples. state property ref. dry acid 30min 60min 30min 60min ultimate tensile stress value mpa (σult) 496 425 338 485 482 tensile yield stress value mpa (σy) 385 310 207 380 365 extension % 18 13.6 11.2 16 14 fatigue strength value mpa (sf) 223 191.3 151.2 218.3 216.9 modulus of elasticity value (e) gpa 76.3 77.3 75.1 75.75 76 hardness rockwell b value 89.5 94 82 86 96 surface roughness value ra(µm) 0.6 0.73 0.84 0.997 1.4 state �� � �� . �� �� reference �� � �� . �� � . � dry 30min �� � �� . �� � .� � 60min �� � �� . �� � . �� acid 30min �� � �� . �� � .��� 60min �� � �� . �� � .� � sadiq jaffer aziz al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 7181 (2018) 77 fig. 11. surface topographic and microstructure of reference sample of aa 7075-t73 fig. 12. surface topography image for dry and acid mediums (100x). dry 30 min dry 60 min acid 30 min acid 60 min sadiq jaffer aziz al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 7181 (2018) 78 fig. 13. microstructure image for dry and acid mediums (10x). 8. fatigue life, a high cyclic fatigue tests were used at amplitude stress 100 mpa the major increment in fatigue life was for test group of dry with 60 min in microwave furnace 25% compared with its original life and the general equation form of life using (basquin equation, �� � ���� ��),[15]. table 5. the acidic percentage in acidic medium led to corrosion in the surface and occurrence of pits on it. these pits are the places for the initiation of cracks, so the higher surface roughness causing increment in crake propagation, therefore decreasing the fatigue life. where for a test group of acid 60 min the decrement was about 75 %,62.5% for acid 30 min group, for dry 30 min in a microwave furnace group was only 50% reduction percentage. fig.10. 9. for microstructure, it was noticed that when illustrate the microstructures of the specimen surfaces with and without microwaves furnace treating, its clearly notice that changing the treating medium will leads essentially to change the microstructures of the specimen's surfaces treated with microwaves furnace at different medium. the effects clearly noticed for 60min in acid medium, more than for the other medium effect on the microstructure. figs.11and 13. 4. discussion and conclusion 1. in this work it has been found that a certain microwaves furnace duration time could made major effects on one or more of the dry 60 min dry 30 min acid 60 min acid 30 min sadiq jaffer aziz al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 7181 (2018) 79 mechanical properties including fatigue life, ultimate stresses and yielding stress for the alloys used. 2. for ultimate stress and yielding decrement, the reason of this phenomenon is that the heat temperature creates from energy arrived from microwave furnace hardened the surface of the alloy from inside to outside. so, when the surface cooled, the grin cells size became smaller compared with the internal grin cells which still at its original size because it cooled slower, so when sample had been tested for tensile test and check the result it was found that a decrement occurs. figs 11-13 shows the effects of dry and acidic mediums at the surfaces of the alloys. 3. for elongation at break, the determined results showed that the alloys brittleness is raised due to the excessive heat from the microwaves furnace with deference to duration time, which make some changes in nature of the alloy surface leads the gran size of both alloys to be changed figs 11and 13. the extension of these alloys is reduced generally from references due to these reasons above. 4. the fatigue strength is an indication of both ultimate stress, yielding and elongation, and since all were decreased essentially that will leads to decrease its value. 5. the acidic contains in acid medium led to corrosion in the surface and occurrence of pits on it, these pits are the place for the initiation of cracks and the higher hardness of the surface and high surface roughness led to increasing in crake propagation so decrease the fatigue life, figs 12and 13. 6. using a microwaves furnace might be useful if knowing its effects on the mechanical properties because that will shorten both the time and cost of changing these properties into certain levels by only using suitable method and/or duration time and amount of heat. 7. the great benefits of availability of microwaves furnace in industrial application was found that these microwaves furnace changes it's mechanical properties in deferent levels than that for classical heat treatment methods, this change depends upon the parameters applied from changing the time duration to heat amount and different conditions, the amount of mechanical properties that changed even if it was not huge in some properties but clearly noticed especially if we know that this application is safe and cheap with respect to other applications which gives this processes privilege as the other applications doesn't optimize the material beater, so for those how need quick not expensive easily handled safe and with acceptable change of mechanical properties, the microwaves furnace is the best choice for them. 8. the study clearly shows that there is no harm of using aluminum alloy in microwaves furnace. 5. references [1] wai leong eugene wong, and manoj gupta” using microwave energy to synthesize light weight/energy saving magnesium based materials” technologies, 3, 1-18, 2015 [2] xiang sun, jiann-yang hwang∗, xiaodi huang, bowen li, shangzhao shi” effects of microwave on molten metals with low melting temperatures” journal of minerals & materials characterization & engineering, vol. 4, no. 2, pp 107-112, 2005 [3] penchal reddy matli, rana abdul shakoor, adel mohamed amer mohamed and manoj gupta ” microwave rapid sintering of almetal matrix composites: a review on the effect of reinforcements, microstructure and mechanical properties” mdpi metals 2016, 6, 143; doi:10.3390/met6070143 [4] michael vollmer” physics of the microwave oven” germany, physical education 39 (1).2004. [5] noboru yoshikawa” fundamentals and applications of microwave heating of metals” japan, journal of microwave power and electromagnetic energy, 44 (1), pp. 4-13, 2010. [6] manoj gupta and wong wai leong, eugene “microwaves and metals “john wiley & sons (asia) pte ltd, 2 clementi loop, 02-01, 2007. [7] ahmed adnan al-qaisy, eng. sameh fareed hasan, najmuldeen yousif mahmood” study sadiq jaffer aziz al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 7181 (2018) 80 the effects of microwave furnace heat on the mechanical properties and estimated fatigue life of aa 2024-t3” journal of engineering, no.10, vol.23, 2017 [8] satnam singh, dheeraj gupta, vivek jain and apurbba k. sharma” microwave processing of materials and applications in manufacturing industries” taylor & francis group materials and manufacturing processes, 30: 1–29, 2015. [9] d. loganathana, a. gnanavelbabub, k. rajkumar and r. ramadoss” effect of microwave heat treatment on mechanical properties of aa6061 sheet metal”science direct, procedia engineering 97,1692 – 1697,2014. [10] li jin-feng, peng zhuo-wei, li chao-xing, jia zhi-qiang, chen wen-jing and zheng zi-qiao” mechanical properties, corrosion behaviors and microstructures of 7075 aluminum alloy with various aging treatments” transaction of nonferrous metals society of china 18, 755-762.2008. [11] zabih-alah khansha1, mohammad r. saeri2 and sasan otroj” study of stress corrosion cracking of aa7075-t6 aluminum alloy by chromate coatings in aerial industry” indian journal of fundamental and applied life sciences issn: 2231– 6345 (online).2015. [12] fatima ali hussain” fatigue of 7075t6 al alloy under different conditions of corrosion” a thesis of master al-mustansiriyah university, materials engineering department. 2016. [13] adeyemi dayo isadare, bolaji aremo, mosobalaje oyebamiji adeoye, oluyemi john olawale, moshood dehinde shittu” effect of heat treatment on some mechanical properties of 7075 aluminum alloy” materials research.; 16(1): 190-194, 2013. [14] astm, standard specification for aluminum and aluminum-alloy sheet and plate, usa, 2012. [15] f. c. campbell" elements of metallurgy and engineering alloys" american society for metals (asm), p 243-264, 2008 �ل ال�ندسية ا��وارزمي جلةم عز ز جعفر صادق� )2018( 71-81 صفحة ،2دالعد ،14دا 81 aa 7075-t73التحقق من تأثير افران الموجات الدقيقة على الخواص الميكانيكية وعمر الكلل ل جاف وحامض ةمع معامل ***رفيف جمعة سلمان **احمد عدنان شندوخ *فر عزيزصادق جع *،**،*** قسم الهندسة الميكانيكية/ الجامعة التكنلوجية s-j-aziz@hotmail.com :ال��يد االلك��و�ي* abomrem2004@gmail.com :ال��يد االلك��و�ي** rafef1362@gmail.com :ال��يد االلك��و�ي*** الخالصة الهدف من هذه الدراسة هو معرفه .حرارةطاقة الموجات الدقيقة وتحويلها الى على امتصاصطة قابلية المواد ساالتسخين بالموجات الدقيقة يتسبب بو في فرن المايكرويف وبأوساط مختلفة (جاف ومحلول aa7075-t73التأثيرات التي سوف تحدث عند المعاملة الحرارية لسبيكة االلمنيوم عالية المقاومة أن هناك للطاقة الحرارية لفرن الموجات الدقيقة يةلعملأظهرت النتائج ا .) دقيقة على الخواص الميكانيكية وعمر الكلل(30,60حامضي) عند اوقات مختلف مع االختالف في االوساط والمدة الزمنية ) اإلجهاد االقصى، اجهاد الخضوع، مقاومة الكالل، عمر الكالل والصالدة(اختالفات في الخواص الميكانيكية وفيما يتعلق بعمر .مقارنة مع القيم القياسية الحاالتمقاومة الكالل لجميع و انخفض كل من اإلجهاد االقصى، اجهاد الخضوع . مقارنتا مع عينات غير معاملة وعالوة على ذلك، تم التوصل .فقط %٢٥ دقيقة في فرن الموجات الدقيقة كانت ٦٠الكالل، أظهرت النتائج أن الزيادة في عمر الكالل لحالة اختبار الجاف .العينات بدون معاملة حالةالجاف من ٣٠ل %٥، %٧٫٣دقيقة عن ٦٠إلى زيادة في مدى صالبة الختبار حالة الحامض في al-khwarizmi engineering journal al-khwarizmi engineering journal,vol. 11, no. 2, p.p. 6273 (2015) temperature effect on photovoltaic modules power drop qais mohammed aish institute of technology/ baghdad email: abdgold171@yahoo.com (received 20 february 2014; accepted 25 january 2015) abstract in order to determine what type of photovoltaic solar module could best be used in a thermoelectric photovoltaic power generation. changing in powers due to higher temperatures (25 o c, 35 o c, and 45 o c) have been done for three types of solar modules: monocrystalline , polycrystalline, and copper indium gallium (di) selenide (cigs). the prova 200 solar panel analyzer is used for the professional testing of three solar modules at different ambient temperatures; 25 o c, 35 o c, and 45 o c and solar radiation range 100-1000 w/m 2 . copper indium gallium (di) selenide module has the lowest power drop (with the average percentage power drop 0.38%/ o c) while monocrystalline module has the highest power drop (with the average percentage power drop 0.54%/ o c), while polycrystalline module has a percentage power drop of 0.49%/ o c. keywords: energy gap, pv modules, pv power, temperature dependence. 1. introduction photovoltaics, or solar panels that produce electricity, are affected by their operating temperature, which is primarily a product of the ambient air temperature as well as the level of sunlight. the pronounced effect that the operating temperature of a photovoltaic (pv) cell/module has upon its electrical efficiency is well documented. there are many correlations expressing tc, the pv cell temperature, as a function of weather variables such as the ambient temperature, ta, and the local wind speed, vw, as well as the solar radiation flux/irradiance, gt, with material and system-dependent properties as parameters, e.g., glazing-cover transmittance, τ, plate absorptance, α etc [1] . an equally large number of correlations expressing the temperature dependence of the pv module‟s electrical efficiency, ƞc, can also be retrieved, although many of them assume the familiar linear form, differing only in the numerical values of the relevant parameters which, as expected, are material and system dependent. many correlations in this category express instead the module‟s maximum electrical power, pm, which is simply related to τc through the latter‟s definition (ƞc = pm (under standard test conditions; 25 o c and gt=1000 w/m 2 ) /agt), with a being the aperture area), and form the basis of various performance rating procedures. 2. pv power output dependence on module operating temperature the prediction of pv module performance in terms of electrical power output in the field, that is, the deviation from the standard test conditions reported by the manufacturer of the module. for example, a recently proposed correlation for pv power is in which τpv is the transmittance of the pv cells outside layers [2a,b]. a number of correlations found in the literature for pv electrical power as a function of cell/module operating temperature and basic environmental variables. many of them are linear, while others qais mohammed aish al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 6273 (2015) 63 are more complex, such as the following nonlinear multivariable regression equation [3] , 𝑃𝑚𝑝 = 𝑑1 + 𝑑2𝑇𝑐 + 𝑑3[ln 𝐺𝑇 ]𝑚𝑑4𝑇𝑐[ln 𝐺𝑇 ]𝑚 …(1) resulting from an analysis which addresses the fact that the cells within a module are not identical. (here, dj, j = 1–4 and m are model parameters.) another unusual nonlinear correlation [4] gives a correction coefficient for the output power of a water cooled pv system, namely. 𝑃 = 𝑉𝑐𝑇𝑐[1 − 𝐺𝑇−500 2∗10−4 + 𝐶𝑇𝑐 4∗104 50 − 𝑇𝑐)2 …(2) in which vc and ic are the output voltage and current, respectively, while the parameter ctc takes values 1 or 3, for values of tc below or above 50 o c, respectively. with regard to the wind‟s indirectly beneficial effect of lowering the operating temperature by forced convection and, thus, increasing the power output of the modules, the available model [5], is of the form: 𝑃 = 𝐺𝑇 𝑏1 + 𝑏2𝐺2 + 𝑏3𝑇𝑎 + 𝑏4𝑉𝑓 …(3) in this nonlinear equation, vf is the free-stream local wind speed, i.e., it is measured at a height of 10 m above ground, and the regression coefficients bj, j = 1–4 are determined using solar radiation flux values above 500 w/m 2 [6]. the steady-state power balance determines cell temperature: the input is the absorbed luminous power, which is partially converted into useful electrical output and the rest is dissipated into the surroundings. convection is the main mechanism for heat dissipation in terrestrial, flat plate applications, and radiation is the second nonnegligible mechanism of heat dissipation. a common simplifying assumption is made that the cell-ambient temperature drop increases linearly with irradiance. the coefficient depends on module installation, wind speed, ambient humidity and so on, though a single value is used to characterize a module type [7]. this information is contained in the nominal operating cell temperature (noct), which is defined as the cell temperature is measured under open-circuit when the ambient temperature is 20◦c, irradiance is 0.8 kw/m 2 and wind speed is 1 m/s. tnoct usually values around 45°c. for variations in ambient temperature and irradiance the cell temperature (in o c) can be estimated quite accurately with the linear approximation [8]; 𝑇𝑐 = 𝑇𝑎 + 𝑇𝑁𝑂𝐶𝑇 −20 0.8 𝑘𝑊/𝑚2 𝐺𝑇 …(4) solar panels work best in certain weather conditions, but since the weather is always changing and as engineers are installing solar panels all over the world in different climate regions, most panels do not operating under ideal conditions. that is why it is important for engineers to understand how panels react to different weather conditions. with this knowledge, they can design ways to improve the efficiency of solar panels that operate in non-optimal conditions. in some cases, they design cooling systems to keep the panels within certain temperatures. for example, solar power plants in extremely hot climates may pass a cool liquid behind the panels to pull away heat and keep the panels cool. this is similar to how your body might sweat as a way to stay cool if you were on that run in the 110 ºf air temperature [8]. while it is important to know the temperature of a solar pv panel to predict its power output, it is also important to know the pv panel material because the efficiencies of different materials have varied levels of dependence on temperature. therefore, a pv system must be engineered not only according to the maximum, minimum and average environmental temperatures at each location, but also with an understanding of the materials used in the pv panel. the temperature dependence of a material is described with a temperature coefficient. for polycrystalline pv panels, if the temperature decreases by one degree celsius, the voltage increases by 0.12 v so the temperature coefficient is 0.12 v/c. effect of temperature on module output relative to standard condition (tc=25 o c and gt= 1000 w/m 2 ) is available in fig.1 fig. 1. the effects of a negative temperature coefficient of power on pv module performance [9]. qais mohammed aish al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 6273 (2015) 64 3. experimental measurements three types of photovoltaic solar cells are selected to study temperature effect on the output power drop of the solar modules: 1. monocrystalline cells are cut from a single crystal of siliconthey are effectively a slice from a crystal. in appearance, it will have a smooth texture and you will be able to see the thickness of the slice. these are the most efficient and the most expensive to produce [10]. they are also rigid and must be mounted in a rigid frame to protect them (see fig.2). fig. 2. monocrystalline panel. 2. polycrystalline (or multicrystalline) cells are effectively a slice cut from a block of silicon, consisting of a large number of crystals. they have a speckled reflective appearance and again you can you see the thickness of the slice [10]. these cells are slightly less efficient and slightly less expensive than monocrystalline cells and again need to be mounted in a rigid frame (see fig. 3). fig. 3. polycrystalline panel. 3. copper indium gallium (di) selenide (cigs) is a i-iii-vi2 semiconductor material composed of copper, indium, gallium, and selenium. the material is a solid solution of copper indium selenide (often abbreviated "cis") and copper gallium selenide[10]. it has a chemical formula of cuinxga (1-x)se2 where the value of x can vary from 1 (pure copper indium selenide) to 0 (pure copper gallium selenide). cigs is a tetrahedrally bonded semiconductor, with the chalcopyrite crystal structure, and a band gap varying continuously with x from about 1.0 ev (for copper indium selenide) to about 1.7 ev (for copper gallium selenide)(see fig.4). among many uses, cigs is best known as an alternate solar cell material in thin-film solar cells[10]. in this role, cigs has the advantages of being able to be deposited on flexible substrate materials, producing highly flexible, lightweight solar panels. improvements in efficiency have made cigs a leader among alternative cell materials. fig. 4. copper indium gallium (di) selenide (cigs). 3.1. experimental procedure the prova 200 solar panel analyzer (fig.5) is used for the professional testing and maintenance of solar panels and modules. in addition to maintenance and installation of solar panels, the prova 200 solar panel analyzer can be used in the manufacturing and research of solar panels and cells. table 1 provides the general specification of prova 200. the portability of this device means that it is also useful in quality assurance at various stages on the production line and can be taken from one location to another. when used in the installation of solar panels, the prova 200 solar panel analyzer assists in determining the proper inverter size as well as optimum power output position of panels and helps identify defective cells or panels that have worn out over time. the solar panel analyzer also provides the user with current and voltage (i-v) test curves, maximum solar power as well as current and voltage. solar cell efficiencies are also easily determined using the unit. prova 200 have a software supply by http://en.wikipedia.org/wiki/alkali_metal http://en.wikipedia.org/wiki/group_3_element http://en.wikipedia.org/wiki/group_6_element http://en.wikipedia.org/wiki/semiconductor_material http://en.wikipedia.org/wiki/copper http://en.wikipedia.org/wiki/indium http://en.wikipedia.org/wiki/gallium http://en.wikipedia.org/wiki/selenium http://en.wikipedia.org/wiki/solid_solution http://en.wikipedia.org/wiki/tetrahedral http://en.wikipedia.org/wiki/chemical_bond http://en.wikipedia.org/wiki/chalcopyrite http://en.wikipedia.org/wiki/bandgap http://en.wikipedia.org/wiki/solar_cell http://en.wikipedia.org/wiki/copper_indium_gallium_selenide_solar_cells http://en.wikipedia.org/wiki/copper_indium_gallium_selenide_solar_cells qais mohammed aish al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 6273 (2015) 65 manufacturing company to calibrate the device automatically. this process is done periodically the device is connect with the internet. fig. 5. the prova 200 solar panel analyzer. table 1, general specifications of prova 200. battery type rechargeable, 2500mah(1.2v)*8 ac adaptor ac 110v or 220v input dc 12v / 1~3a output dimension 257(l) * 155(w) *57(h) mm weight 1160g / 40 ooz operation environment 0 o c ~ 50 o c,85% rh temperature coefficient 0.1% of full scale/ c (<18c or >28c) storage environment -20c ~ 60c ,75%c accessories user manual * 1, ac adaptor*1 optical usb cable*1 software cd *1, software manual *1 kelvin clips( 6a max) *1 set 3.1.1. connecting wires (connectors) the terminals of the solar cell are connected as in fig.6. in this work, the system of measurements is consists of silicon solar cell as it is presented in fig.4. fig.4 shows the set-up of our experiment. it is based on the simple solar-cell experiment. table 2 gives the general specification of this cell. fig. 6. wires connections. table 2, solar modules specifications. module type area, m 2 voc, v isc, a peak power , w peak voltage , v peak current , a energy gap, ev production date cigs 0.03 11 0.33 1.8 6.6 0.28 1.35 2013 monocrystalline 0.36 19.5 2.8 35 15.8 2.3 1.12 2013 polycrystalline 1 22 8.1 130 18.5 6.0 1.75 2013 3.1.2. solar panel parameters measure the main parameters that characterize a photovoltaic panel (fig.4) are: 1. short circuit current (isc): the maximum current provided by the panel when the connectors are short circuited. 2. open circuit voltage (voc): the maximum voltage that the panel provides when the terminals are not connected to any load (an open circuit). 3. maximum power point (pmax): the point where the power supplied by the panel is at maximum, where pmax = imax x vmax. the maximum power point of a panel is measured in watts (w) or peak watts (wp). it is important not to forget that in normal conditions the panel will not work at peak conditions, as the voltage of operation is fixed by the load or the regulator. typical values of vmax and imax should be a bit smaller than the isc and voc . qais mohammed aish al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 6273 (2015) 66 4. fill factor (ff): the relation between the maximum power that the panel can actually provide and the product isc .voc. this gives you an idea of the quality of the panel because it is an indication of the type of iv characteristic curve. the closer ff is to 1, the more power a panel can provide. common values usually are between 0.7 and 0.8. 5. efficiency (𝜂): the ratio between the maximum electrical power that the panel can give to the load and the power of the solar radiation (pl) incident on the panel. this is normally around 10-12%, depending on the type of cells (monocrystalline, polycrystalline, amorphous or thin film). considering the definitions of point of maximum power and the fill factor we see that: 𝜂= pmax/pl= ff.isc.voc / pl … (6) the prova 200 experimental measurement steps are as follow: 1connect the solar panel solar panel as in fig.6 2connect the solar panel terminal t1 and t2 with the prova 200 device (kelvin clip connection) as in fig. 6 3input the value of surface area in square meters of the panel and the measured values of solar radiation intensity in w/m 2 4the measurements is made at a sunny day and at different time intervals of the day so as to get the adjusted values of solar radiation intensity (100, 200, 300, 400, 500, 600, 700, 800, 900, and 1000 w/m 2 and solar cell temperatures (25 o c, 35 o c, and 45 o c). 5prova 200 will be made auto scanning at a variable load in ohm (0 to ∞) 6prova 200 output are: voltage (vnow), open circuit voltage (voc), short circuit current (isc), , maximum power point (pmax), maximum current (imax), maximumvotage (v max ), fill factor (ff), and efficiency (𝜂). 4. results and discussion the measuring results of the commercial available solar cells from different manufacturers are presented. cell samples have been investigated regarding their i-v characteristics at different solar intensities in a range 100-1000 w/m 2 and the ambient temperature between (25oc, 35oc, and 45oc). all the measurements and the characteristics of these cells have been made within the date of september and november 2013. the data obtained for i-v characteristics and p-v curve for three types of solar modules; monocrystalline, polycrystalline and copper indium gallium (di)selenide under the specific solar radiation intensities (100-1000 w/m 2 ) and ambient temperatures, 25 o c,35 o c, and 45 o c are shown in tables 3 to 5. solar cells powers vary under temperature changes. the change in temperature (increasing values) will affect the power output from the cells (because of the problem of loss of electricity as a result of heat buildup and non-ideal behavior of semiconductor with the corresponding temperature increase). the voltage is highly dependent on the temperature and an increase in temperature will decrease the voltage. equation 1, equation 2 and equation 3 repent the relationship between solar module power and other environment parameters (solar radiation g, ambient temperature ta, solar module temperature tc; which is strongly function with ambient temperature ta(see equation 4), and wind speed vf). fig.7a,fig.8a, and fig.9a show the effect of temperature on i-v characteristic of three pv modules at constant solar radiation(1000 w/m 2 ) and different ambient temperatures; 25 o c,35 o c, and 45 o c . with decreasing temperatures, pv currents decrease slightly but pv voltage increase clearly to the all corresponding pv module. as fig.7b, fig.8b, and fig.9b indicate, output powers of photovoltaic modules increase with decreasing the selected temperatures (i.e. 25 o c, 35 o c, and 45 o c). however, copper indium gallium (di)selenide has the lowest power drop (with the average percentage power drop 0.38%/ o c) while monocrystalline has the highest power drop (with the average percentage power drop 0.54%/ o c) according to the tabulated power values in tables 3,4, and 5). the percentage of power drop of polycrystalline module is 0.49%/ o c). radziemska [11] found for the monocrystalline module that the average output power drop is equal to 0.66%/ o c. it has been found that the maximum power density of the two modules decreases with increasing module temperature, where the maximum power density of the mono-crystalline and the poly-crystalline modules for temperature=10 o c was 43.4 mw/cm 2 and 48.76 mw/cm 2 , respectively. increasing the temperature to 50 o c causes the decrease of the power by 25% and 14% to reach values 36.32 mw/cm 2 and 41.88 mw/cm 2 respectively [12]. this results of ref[11] agrees with proposed results that monocrystalline module has the largest values of power drop as compared with polycrystillane module. one should expect any device utilizing semiconductors to be quite sensitive to qais mohammed aish al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 6273 (2015) 67 temperature deviations from normal operating temperatures, and solar cells are no exception. an increase in the operating temperature of a solar cell (or the corresponding ambient temperature) typically has the effect of slightly increasing the cell's short-circuit current and significantly decreasing the cell voltage. therefore, as the temperature of the solar cell rises, the result is that the maximum efficiency decreases (the area of the power rectangle under the vi curve decreases). table 3, cigs electrical measured data at different solar intensities (100-1000 w/m 2 ) and different temperatures, 25 o c, 35 o c, and 45 o c. ff % ɳ imax a vmax v pmax w isc a voc v vnow v t o c g w/m 2 0.67 8.63 0.026 7.12 0.19 0.030 9.22 9.42 25 100 0.654 7.85 0.027 6.76 0.188 0.032 8.76 9.332 35 0.619 6.125 0.028 6.425 0.183 0.0347 8.545 9.866 45 0.66 8.51 0.040 7.48 0.298 0.046 9.41 9.44 25 200 0.645 5.689 0.038 7.233 0.278 0.045 9.01 9.21 35 0.630 4.175 0.0362 6.921 0.250 0.0439 9.058 9.048 45 0.65 8.43 0.078 7.41 0.583 0.090 9.81 9.84 25 300 0.64 6.34 0.061 7.19 0.443 0.076 9.561 9.571 35 0.650 4.586 0.059 6.985 0.412 0.0682 9.309 9.315 45 0.64 7.73 0.092 7.31 0.678 0.105 9.91 9.92 25 400 0.639 5.471 0.072 7.201 0.521 0.095 9.567 9.435 35 0.633 4.033 0.067 7.182 0.484 0.0791 9.359 9.362 45 0.63 7.30 0.117 7.17 0.843 0.133 10.01 10.04 25 500 0.649 6.54 0.105 7.166 0.758 0.122 9.893 9.89 35 0.650 4.967 0.104 7.158 0.745 0.119 9.606 9.372 45 0.61 7.30 0.140 6.93 0.970 0.157 10.09 10.11 25 600 0.6211 6.235 0.117 7.102 0.837 0.143 9.78 9.78 35 0.639 4.584 0.112 7.328 0.825 0.134 9.618 9.587 45 0.59 6.4 0.150 6.92 1.093 0.173 10.12 10.14 25 700 0.604 5.89 0.141 6.988 0.989 0.166 9.78 9.43 35 0.622 4.600 0.137 7.047 0.966 0.160 9.656 8.730 45 0.57 6.23 0.170 6.73 1.146 0.196 10.18 10.20 25 800 0.611 5.67 0.154 6.76 1.042 0.178 9.98 9.71 35 0.615 4.084 0.144 6.780 0.980 0.165 9.619 9.596 45 0.55 6.14 0.186 6.58 1.229 0.217 10.22 10.23 25 900 0.596 5.43 0.172 6.863 1.186 0.201 9.897 10.01 35 0.618 4.220 0.165 6.902 1.139 0.190 9.674 9.972 45 0.52 6.06 0.217 6.42 1.394 0.256 10.36 10.37 25 1000 0.567 5.246 0.197 6.642 1.310 0.237 10.01 9.36 35 0.582 4.188 0.182 6.883 1.254 0.215 9.995 8.428 45 qais mohammed aish al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 6273 (2015) 68 table 4, moncrystaline electrical measured data at different solar intensities (100-1000 w/m 2 ) and different temperatures, 25 o c, 35 o c, and 45 o c. ff ƞ % i max a vmax v pmax w isc a voc v vnow v t 0 c g w/m 2 0.48 4.21 0.131 11.7 1.5 0.196 16.19 16.2 25 100 0.521 6.74 0.196 11.88 2.34 0.256 15.69 15.98 35 0.568 8.322 0.25 11.94 2.966 0.339 15.55 15.43 45 0. 61 5.54 0.299 13.58 4.04 0.383 17.4 17.42 25 200 0.621 5.893 0.32 12.92 4.16 0.413 16.68 16.58 35 0.637 6.393 0.373 12.31 4.603 4670. 15.70 15.79 45 0.65 5.90 0.426 14.4 6.52 0.556 17.94 17.99 25 300 0.645 4.78 0.458 13.55 6.21 0.52 16.567 16.59 35 o.636 4.7.5 0.403 12.59 5.o82 0.5 15.97 16.05 45 0.67 6.53 0.693 14.63 10.1 0.825 18.18 18.2 25 400 0.6632 6.34 0.697 14.01 9.77 0.805 17.409 17.94 35 0.65. 5.733 0.626 13.18 8.256 0.764 16.61 16.64 45 0.79 6.42 0.73 14.71 12.6 0.972 18.25 18.3 25 500 0.734 6.432 0.820 13.69 11.23 0.989 17.54 17.345 35 0.676 6.454 0.870 13.34 11.61 1.028 16.69 16.72 45 0.69 6.37 0.952 14.81 14.1 1.106 18.36 18.4 25 600 0.689 6.034 0.921 14.21 13.10 1.118 17.643 17.89 35 0.680 5977 0.954 13.52 12.91 1.127 16.83 16.85 45 0.69 6.23 1.06 15.03 15.97 1.23 18.49 18.5 25 700 0.684 6.196 1.04 14.98 15.63 1.278 17.567 17.98 35 0.682 6.188 1.154 13.59 15.59 1.342 17.02 17.04 45 0.7 7.3 1.4 15.3 21.5 1.62 18.79 18.8 25 800 0.697 6.45 1.33 14.76 19.74 1.56 18.045 17.694 35 0.685 5.853 1.238 13.61 16.85 1.439 17.08 17.09 45 0.7 6.9 1.507 15.2 22.9 1.71 18.88 18.89 25 900 0.69 6.56 1.39 14.56 20.33 1.687 17.578 17.67 35 0.686 6.020 1.426 13.67 19.50 1.658 17.13 17.11 45 0.71 7.2 1.72 15.4 26.4 1.95 19.05 19.05 25 1000 0.689 6.84 1.625 14.63 23.78 1.934 18.49 18.56 35 0.687 6.323 1.684 13.51 22.67 1.928 17.16 17.15 45 qais mohammed aish al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 6273 (2015) 69 table 5, polycrystalline electrical measured data at different solar intensities (100-1000 w/m 2 ) and different temperatures, 25 o c, 35 o c, and 45 o c. ff ƞ % imax a vmax v pmax w isc a voc v vnow v t 0 c g w/m 2 0.66 13.92 0.8 17.40 13.92 1.2 17.5 17.6 25 100 0.723 14.054 0.85 16.32 13.88 1.15 17.89 18.54 35 0.758 14.90 0.931 15.89 14.88 1.050 18.69 19.31 45 0.81 14.00 1.600 17.50 28.00 1.800 19.00 19.10 25 200 0.788 10.48 1.39 16.88 23.54 1.76 18.998 19.04 35 0.766 9.221 1.135 16.23 18.42 1.720 18.91 18.91 45 0.82 10.5 2.4 17.52 42.05 2.5 20.50 20.50 25 300 0.794 9.78 1.995 16.922 33.761 2.32 20.056 19.78 35 0.755 9.480 1.752 16.21 28.41 1.905 19.23 19.23 45 0.78 12.8 2.9 17.7 51.3 3.1 21.00 21.01 25 400 0.778 11.34 2.371 17.21 40.81 3.067 20.67 20.45 35 0.765 9.356 2.295 16.28 37.38 2.513 19.42 19.40 45 0.73 10.98 3.1 17.72 54.9 3.52 21.08 21.09 25 500 0.737 9.65 2.86 17.32 49.60 3 20.862 20.23 35 0.747 8.631 2.569 16.77 43.11 2.965 19.46 19.46 45 0.84 10.6 3.5 17.76 63.9 3.56 21.13 21.14 25 600 0.789 10.34 3.55 17.22 61.22 3.87 20.46 20.78 35 0.758 10.07 3.720 16.22 60.36 4.043 19.67 19.65 45 0.8 10.9 4.3 17.8 76.9 4.5 21.24 21.25 25 700 0.778 9.67 4.367 16.92 73.89 4.456 20.46 20.68 35 0.756 9.202 3.956 16.26 64.35 4.332 19.63 19.61 45 0.77 10.48 4.7 17.84 83.84 5.06 21.39 21.4 25 800 0.765 10.04 4.712 17.35 81.76 5.21 20.56 20.976 35 0.752 9.863 4.906 16.06 78.82 5.332 19.56 19.62 45 0.78 10.49 5.24 18.02 94.42 5.6 21.52 21.51 25 900 0.762 9.678 5.234 17.47 91.442 5.678 20.567 20.47 35 0.753 9.378 5.262 16.04 84.40 5.719 19.59 19.59 45 0.8 10.07 5.5 18.31 100.7 5.8 21.59 21.6 25 1000 0.793 9.67 5.6 17.45 97.87 5.98 20.78 20.68 35 0.746 9.220 5.744 15.95 92.10 6.276 19.65 19.49 45 qais mohammed aish al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 6273 (2015) 70 fig. 7a. output i-v characteristics of the copper indium gallium (di) selenide with different temperatures and constant solar radiation (1000 w/m 2 ). fig. 7b. output p-v characteristics of the copper indium gallium (di) selenide with different temperatures and constant solar radiation (1000 w/m2). fig. 8a. output i-v characteristics of monocrystalline with different temperatures and constant solar radiation (1000 w/m2). fig. 8b. output p-v characteristics of monocrystalline with different temperatures and constant solar radiation (1000 w/m2). fig. 9a. output i-v characteristics of polycrystalline with different temperatures and constant solar radiation (1000 w/m2). fig. 9b. output p-v characteristics of polycrystalline with different temperatures and constant solar radiation (1000 w/m2). qais mohammed aish al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 6273 (2015) 71 5. conclusions the operating temperature plays a central role in the photovoltaic conversion process. the power outputs of pv modules depend on the operating temperature, decreasing with increasing the ambient temperatures. according to the experimental measurements solar modules powers decrease against temperatures increasing. it became clear that as the temperature raises the power drops. compare to the experimental measurements, in regard to power drop percentage per temperature vary from module to another, which are for monocrystalline module > polycrystalline module > pcopper indium gallium (di)selenide. notation a ideality factor a aperture surface area of pv module (m 2 ) gt solar radiation flux (irradiance) on module plane (w/m 2 ) p electrical power (w) ff fill factor g solar radiation, w/m 2 il photocurrent, a imaxp imp maximum current at pmax , ma io saturation current, a ip operating current, a isc current at short circuit, ma pl power of solar radiation, w pmax maximum solar power, w rl load resistance, ω ta ambient temperature, o c tc cell/module operating temperature , o c tnoct nominal operating cell temperature, o c vmaxp vmp maximum voltage at pmax, v v voltage (v) vf free stream wind speed (m/s) vw wind speed at monitored surface (m/s) voc voltage at open circuit, v greek letters ƞ cell/module electrical efficiency,% τ solar transmittance of glazing subscripts 0 at src a ambient b back side c cell (module) f free stream l loss m maximum, at maximum power point oc open circuit ref reference value, at reference conditions sc short circuit 6. reference [1] skoplaki e. and j.a. palyvos, “on the temperature dependence of photovoltaic module electrical performance: a review of efficiency/power correlations” , solar energy 83 , 614–624, 2009. [2-a] jie, j., hua, y., gang, p., bin, j., wei, h.. study of pv-trombe wall assisted with dc fan. building and environment 42, 3529– 3539, 2007a. [2-b] jie, j., hua, y., wei, h., gang, p., jianping, l., bin, j.. modeling of a novel trombe wall with pv cells. building and environment 42,1544–1552, 2007b. [3] rosell, j.i., iba´n˜ ez, m.. modelling power output in photovoltaic modules for outdoor operating conditions. energy conversion and management 47, 2424–2430, 2006. [4] furushima, k., nawata, y., sadatomi, m.,. prediction of photovoltaic power output considering weather effects. in: ases conference solar 2006 – renewable energy key to climate recovery. july 7–13, denver, colorado, 2006. [5] farmer, b.k.,. pvusa model technical specification for a turnkey photovoltaic power system. appendix c, p. c2, 1992 [6] meyer, e.l., van dyk, e.e.. development of energy model based on total daily irradiation and maximum ambient temperature. renewable energy 21, 37–47, 2000. [7] fesharaki v.jafari, majid dehghani, j. jafari fesharaki the effect of temperature on photovoltaic cell efficiency, proceedings of the 1st international conference on emerging trends in energy conservation – etec tehran, tehran, iran, 2011. [8] luque. a and hegedus. s.. ” handbook of photovoltaic scienceand engineering” . john wiley & sons ltd, the atrium, southern gate, chichester, west sussex po19 8sq, england, pp. 296-297, 2003. [9] david l. king, jay a. kratochvil, and william e. boyson, “temperature coefficients for pv modules and arrays: measurement methods, difficulties, and results” the 26th ieee photovoltaic qais mohammed aish al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 6273 (2015) 72 specialists conference, september, anaheim, california, 1997. [10] david tan ang kian seng „hand book of solar photovotiac system (pv) systems‟ , singapore, 2011. [11] radziemska, e.,” the effect of temperature on the power drop in crystalline silicon solar cells”, renewable energy 28, 1–12, 2003. [12] el-shaer, a., m. t. y. tadros, m. a. khalifa,” effect of light intensity and temperature on crystalline silicon solar modules parameters”, international journal of emerging technology and advanced engineering, volume 4, issue 8, august 2014. (2015) 6273، صفحة 2، العذد11دالخىارزمً الهنذسٍة المجلجلة م قٍس محمذ عاٌص 73 الخالٌا الشمسٍة تأثٍر درجة الحرارة على انخفاض قذرة وحذات شقٍس محمذ عاي بغذاد / الىجٍوهعهذ الخكي abdgold171@yahoo.com :البرَذ االلكخروًٍ الخالصة حغُر القذرة ًخُجُت زَبدة درجبث الحرارة . َكىى اسخخذاههب أفضل هع زَبدة درجت الحرارة هي اجل ححذَذ أٌ ًىع هي وحذاث الخالَب الشوسُت (25 o c, 35 o c, and 45 o c) جلُىم والسلٌُبد -أًذَىم -أًىاع هي وحذاث الخالَب الشوسُت وهٍ احبدَت الخبلىر، ثٌبئُت الخبلىر، و ًحبس ةحن اَجبدٍ لثالد درجت 45، و 35، 25: لخحلُل الخالَب الشوسُت لفحص وحذاث الخالَب الشوسُت الثالد وفٍ درجبث حرارة هخخلفت 200لقذ اسخعول جهبز بروفب . الثٌبئٍ فٍ هٍ األقل أًخفبض جلُىم والسلٌُبد الثٌبئٍ -أًذَىم -ًحبسوحذة الخلُت ًىع .واط لكل هخر هربع 1000الً 100ع شوسٍ هئىَت وضوي هذي اشعب /%0.38قذرة o c 0.54 هٍ االعلً احبدَت الخبلىربٌُوب وحذة الخلُت ًىع%/ o c. ٍبٌُوب وحذة الخلُت هخعذدة الخبلىر كبًج ًسبت اًخفبض الفىلخُت ه 0.49%/ o c. <4d6963726f736f667420576f7264202d20dac8c7d320e6e1edcb20e6e6d3c7e320312d3132> al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 15, no. 2, june , (2019) p.p. 112 effect of quenching media variations on the mechanical behavior of martensitic stainless steel abbas kh. hussein* laith k. abbas** wisam n. hasan*** *, **department of materials engineering /university of technology/ baghdad / iraq ***kut technical institute/ middle technical university / baghdad/ iraq *email: www.abbas2000x@gmail.com **email: www.laithka2012@gmail.com ***email: www.weeesam1982@yahoo.com (received 24 june 2018; accepted 4 november 2018) https://doi.org/10.22153/kej.2019.11.002 abstract the purpose of this study is designate quenching and tempering heat treatment by using taguchi technique to determine optimal factors of heat treatment (austenitizing temperature, percentage of nanoparticles, type of base media, nanoparticles type and soaking time) for increasing hardness, wear rate and impact energy properties of 420 martensitic stainless steel. an (l18) orthogonal array was chosen for the design of experiment. the optimum process parameters were determined by using signal-to-noise ratio (larger is better) criterion for hardness and impact energy while (smaller is better) criterion was for the wear rate. the importance levels of process parameters that effect on hardness, wear rate and impact energy properties were obtained by using analysis of variance which applied with the help of (minitab18) software. the variables of quenching heat treatment were austenitizing temperature (985 c˚,1060 c˚),a soaking times (50,70 and 90 minutes) respectively, percentage of volumetric fractions of nanoparticles with three different levels(0.01, 0.03 and 0.08 %) were prepared by dispersing nanoparticles that are (α-al2o3,tio2 and cuo) with base fluids (de-ionized water, salt solution and engine oil).the specimens were tempered at 700°c after quenching of nanofluids for (2 hours).the results for ( s/n) ratios showed the order of the factors in terms of the proportion of their effect on hardness, and wear rate properties as follow: austenitizing temperature ( 1060 c˚),type of base media (salt solution), nanoparticles type (cuo), percentage of nanoparticles (0.08%) and soaking time(90min) was the least influence while for the impact energy were as follows: type of base media (oil), austenitizing temperature (985c˚), percentage of nanoparticles (0.01%), nanoparticles type (α-al2o3) and last soaking time (50min). keywords: nanofluids, quenching, hardness, wear, impact energy, taguchi technique. 1. introduction martensitic stainless steels occupy a unique status as engineering materials by virtue of their excellent combination of properties. these steels find extensive application in chemical plants, power generation equipments and many other applications [1,2]. unlike other types of stainless steels, the properties of martensitic stainless steels are greatly modified by normal heat treatment procedures [3,4]. to enhance heat transfer to meet the cooling challenge necessary. new type of quenching media has been developed, it is called nanofluids [5]. nanofluid is a fluid containing nanometer-sized particles, called nanoparticles. these fluids are engineered colloidal suspensions of nanoparticles with sizes typically of the order of (1-100 nm) in a base fluid. choi in 1995 coined the term nanofluids for this new class of heat transfer fluids [6,7]. the nanoparticles used in nanofluids are typically made of metals, oxides, carbides, or carbon nanotubes. nanofluids have novel properties that make them potentially useful in many applications in heat transfer. nanofluids abbas kh. hussein al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 112 (2019) 2 show improved stability compared to the conventional fluids added with micrometer or millimeter-sized solid particles because of its size effect and brownian motion of the nanoparticles in liquids [8].possible reasons of discrepancy in experimental data attributed to the complexity of correlations between nanofluid parameters such as material , concentration, size and shape of nanoparticles and properties as density, ph value and thermal conductivity to obtain on the better type of nanofluids as well as many of heat treatment parameters to get optimum structural material for desired application. this study investigated with the taguchi method to optimize 420 martensitic stainless steel heat treatment process parameters, austenitizing temperature, percentage of nanoparticles, type of base media, type of nanoparticles and soaking time to get the better hardness, wear and impact energy properties. 2. experimental procedure 2.1. materials the following materials were used in the nanofluids synthesis because of its good thermal properties: nano titanium dioxide (tio2) powder, nano aluminum oxide(α-al2o3) powder and copper oxide (cuo) nanoparticle (supplied by zhengzhou dongyao nano materials co.ltd.). the properties of these nanoparticles are given on table (1). those materials were added to base media (deionized water, salt solution (nacl+water) and engine oil). sodium lauryl sulphate as surfactant was used. table1, physical properties of nanoparticles. color crystal form density(g/cm3) volume density (g/cm3) specific surface area (m2/g) purity (%) aps (nm) nanoparticle material white γ 3.91 0.916 160.1 >99.99 50 α-al2o3 white cube 3.9 0.25 220 >99.9 20 tio2 black sphere 6.4 0.30-0.45 120 >99.9 50 cuo 2.2. nanofluid preparation in this research, eighteen types of nanofluid are prepared [(al2o3/ deionized water), (al2o3/ salt solution), (al2o3/ engine oil)], [(tio2/ de ionized water),(tio2/ salt solution), (tio2/ engine oil)], [(cuo/ de ionized water), (cuo / salt solution), (cuo / engine oil)] with volume fractions of (0.01, 0.03 and 0.08%).in this paper nanofluid was prepared by two step method where the given nanoparticle is mixed to the base fluid to obtain suspension. law of mixtures was employed to determination quantity of nanoparticles wanted for preparation of nanofluids. the mass of nanoparticles (mp) and base fluid (mf) are measured with balance of (0.0001 g) an accuracy. the weight percentage (ϕ) can be calculated by using eq (1). ϕ = ���/��� ��� �� ��� ��� … (1) where: φ: volume fraction. mnp: mass of nanoparticle(g). ρnp: density of the nanoparticle(g/l). mbf: mass of the base fluid (g). ρbf: density of the base fluid(g/l) [9]. a mechanical stirrer was used to achieve a homogenously dispersed solution. this method was based on han and rhi (2011) [10] and mahendran et al., (2012), [11]. after preparing the proper mix of the nanoparticles and fluids by mechanical stirrer, nanoparticles are dispersed in fluids using magnetic stirrer. during the process sodium dodecyl sulphate (sds) surfactant is added to the solution in proper proportions to ensure stability of nanofluid. for various purposes, sound energy is used to agitate the particles in nanofluid, this process is known as sonication. by breaking intermolecular interaction, sonication is also used for speed up the dissolution. sonication is more useful when the magnetic stirring was not much effective for given sample. for nanoparticles which were not evenly dispersing in liquids, sonication is most preferable. the sonication process is achieved in two steps were: ainitially sonicate the mixture continuously for (30 min) with sonicator of frequency (40 khz) to obtain uniform dispersion of nanoparticles in fluids, this process is achieved with ultrasonic mixer (luc – 410(50 hz,400w)). b-sonicate the abbas kh. hussein al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 112 (2019) 3 mixture continuously for (90 min) with probe sonicator (model 300 vt ultrasonic homogenizer) of output frequency (20 khz). 2.3. material of the research specimens the 420 martensitic stainless steel samples were taken for this study. the chemical composition analysis of the specimens was carried out at the (specialized institute for inspection and engineering qualifying/iraq) by x-ray fluorescent. the chemical composition of the 420 martensitic stainless steel is shown in table (2). table 2, the chemical composition of 420 martensitic stainless steel specimens. 2.4. heat treatment process eighteen types of heat treatment were performed, these were exhibited of schedule (4). quenching heat treatment was implemented to harden the 420 martensitic stainless steel. quenching heat treatment includes heating of samples to austenitizing temperature in an electric furnace (carbolite cwf 1200 muffle furnace) where the samples was held at (985°c, 1060°c) of heating rate (7°c /min)with soaking times ( 50,70 and 90 min ) to ensure uniformity of temperature throughout the full volume to attain a identical structure of austenite, subsequently each group of samples were quenched in diverse quenching mediums (nanofluids) ,and finally tempered at (700°c) for (2)hours. 2.5. wear and hardness properties calibrated vickers hardness measurements were performed on all the samples to determine the hardness of the martensitic stainless steel in each heat treatment condition. results were reported as adjusted from five tests per sample. all of the procedures were carried out according to the (astm e92-82/e2) standard method. the wear resistance of martensitic stainless steel being studied was evaluated using a pin-on-disc tribometer, according to the testing procedure outlined in (astm designation g 99 95a). the specimens of same dimensions were grinded and polished used for both abrasive wear rate analysis and hardness testing. dimensions of the specimen are (10mm × 10mm × 5mm). a parameter referred to as wear rate used to define the wear severity was calculated using equation (2). w� = �� ��∗�� … (2) where: wr= wear rate. δv= volume loss of the specimen. ss = sliding distance (m). fn = normal load (n). [12] the wear test was carried out with constant sliding speed (200 rpm), time (10 min) and load (1٥ n) to find out the effect of the experiment parameters (austenitizing temperature, percentage of nanoparticles, type of base media, nanoparticles type and soaking time). wear tests are performed under dry nonlubricated condition and at ambient temperature of 25 °c. 2.6. charpy impact test the charpy impact test of the quenched martensitic stainless steel sample was carried on jbs impact testing machine. the specimens were supported horizontally with the v-notch opposite to the strike end. the energy absorbed before fracture was then read directly on the digital gauge of machine. the charpy v-notch test method has been standardized according to the (astm standard e23). 2.7. microstructure analysis the analysis of the microstructures gained for several variants of heat treatment was analyzed by using optical microscopic. in preparation for examination under the optical microscope, the samples were finely polished and etched to expose the microstructure. a villela etchant was chosen from the list of etchants in (astm e407-07) standard practice for micro etching metals and alloys (astm international,2007). the determination of the phases present in the treated samples was carried out by x-ray diffractometry element c% si% mn% p% s% cr% mo% ni% al% cu% fe% composition % 0.279 0.519 0.348 0.029 0.01 12.64 0.065 0.14 0.005 0.055 bal abbas kh. hussein al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 112 (2019) 4 (xrd) technique, using a shimadzu (xdr7000) x-ray. 3. taguchi method the taguchi method is a powerful tool for designing high quality systems based on orthogonal array experiments that provide muchreduced variance for experiments with an optimum setting of process control parameters [13,14]. the method has also been widely used in engineering analysis to optimize performance characteristics through design parameter settings. the taguchi method is based on orthogonal arrays and analysis of variance (anova) to minimize the number of experiments and to effectively improve product quality [14,15]. 4. design of experiment the experimental procedures include parameters (variables) and levels as shown in table (3) based on the taguchi technique. austenitizing temperature, percentage of nanoparticles, type of base media, nanoparticles type and soaking time, these are process parameters that considered for this study. in the present investigation an(l18) orthogonal array was chosen as shown in table (4). the experiments were performed based on the run order generated by taguchi model. this analysis involve the rank based on the delta statistics, which equals the relative value of the effects. the experimental results were transformed into signal-to-noise ratio (s/n). the (s/n) ratio for the (hardness and impact energy) using "larger the better" characteristics as for the wear property using "smaller the better" characteristics, which can be calculated as logarithmic transformation of the loss function is given as: a.larger the better (ltb) � � = −10log101/n∑[1/y !] … (3) b. smaller the better (stb) � � = −10log10∑[y ! /n] … (4) where: y: results of experiments, observations or quality, n: number of trials of repetitions, s: the variance [16]. table 3, control factors and their levels. unit levels control factors symbol oc ----1060 985 austenitizing temperature a ----0.08% 0.03% 0.01% concentration media b ----engine oil salt solution deionized water base media c ----cuo tio2 α-al2o3 nano particles type d min 90 70 50 soaking time e 5. results and discussions 5.1. s/n ratios analysis the (s/n) ratio response was analyzed using the equation (3) for the hardness and impact energy while equation (4) using for wear rate, figures (1,2,3) and table (5) shows the main effects plots of (s/n) ratios for hardness, wear and impact energy. from the figures (1,2,3) and table (5) it is evident that the order of factors by effect was as follows: austenitizing temperature (1060c˚), type of base media (salt solution), nanoparticles type (cuo), percentage of nanoparticles (0.08%) and soaking time(90min) was the least influence while for the impact energy were as follows: type of base media (oil), austenitizing temperature (985c˚), percentage of nanoparticles (0.01%), nanoparticles type (αal2o3) and last soaking time (50min). abbas kh. hussein al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 112 (2019) 5 table 4, signal to noise ratios for the controlling factors considering hardness, wear rate and impact energy. s/n impact energy impact energy (j) s/n wear rate wear rate mm3/n.m s/n hardness hardness (hv) parameters exp.t e d c b a 35.707 61 130.881 2.86e-07 50.931 352 1 1 1 1 1 1 34.807 55 135.318 1.71e-07 52.75 434 2 2 2 1 1 2 34.964 56 134.23 1.94e-07 52.277 411 3 3 3 1 1 3 34.648 54 133.734 2.06e-07 52.063 401 2 1 1 2 1 4 34.151 51 139.755 1.03e-07 53.715 485 3 2 2 2 1 5 35.269 58 134.23 1.94e-07 52.277 411 1 3 3 2 1 6 34.151 51 135.318 1.71e-07 52.527 423 1 2 1 3 1 7 33.442 47 138.839 1.14e-07 53.46 471 2 3 2 3 1 8 35.269 58 134.23 1.94e-07 52.277 411 3 1 3 3 1 9 33.255 46 140.778 9.14e-08 53.962 499 3 3 1 1 2 10 34.486 53 138.839 1.14e-07 53.46 471 1 1 2 1 2 11 34.648 54 137.256 1.37e-07 52.987 446 2 2 3 1 2 12 33.442 47 144.86 5.71e-08 54.712 544 3 2 1 2 2 13 33.442 47 144.86 5.71e-08 54.712 544 1 3 2 2 2 14 34.964 56 135.318 1.71e-07 52.527 423 2 1 3 2 2 15 32.669 43 143.276 6.86e-08 54.453 528 2 3 1 3 2 16 32.869 44 143.276 6.86e-08 54.453 528 3 1 2 3 2 17 34.32 52 138.839 1.14e-07 53.46 471 1 2 3 3 2 18 35 4.29e-04 86 hrb (untreated) table 5, responses table for sn ratio-(hardness, wear rate and impact energy). soaking time nanoparticles type type of base media percentage of nanoparticles austenitizing temperature hardness 52.89455189 52.61841352 53.10786924 52.72776842 52.47512277 level 1 53.03988053 53.35842167 53.75835368 53.33422033 53.85840718 level 2 53.5658625 53.52345973 52.634072 53.43830616 level 3 0.671310612 0.905046212 1.124281686 0.710537741 1.383284414 delta 5 3 2 4 1 rank soaking time nanoparticles type type of base media percentage of nanoparticles austenitizing temperature wear rate 137.1612949 136.046449 138.1410788 136.2169574 135.1706082 level 1 137.2901705 138.5575413 140.1479454 138.7928115 140.8114511 level 2 139.5216235 139.3690986 135.6840646 138.9633199 level 3 2.360328665 3.322649534 4.46388082 2.74636247 5.640842898 delta 5 3 2 4 1 rank soaking time nanoparticles type type of base media percentage of nanoparticles austenitizing temperature impact energy 34.56235025 34.65689387 33.97872639 34.64436004 34.71193002 level 1 34.1963485 34.25332668 33.86619043 34.31925224 33.78830151 level 2 33.99164854 33.84012675 34.90543048 33.78673501 level 3 0.57070171 0.816767126 1.039240057 0.857625031 0.923628509 delta 5 4 1 3 2 rank abbas kh. hussein al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 112 (2019) 6 fig. 1. main effects plots for sn ratios-(hardness). fig. 2. main effects plots for sn ratios(wear rate). fig. 3. main effects plots for sn ratios(impact energy). abbas kh. hussein al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 112 (2019) 7 5.2. anova analysis analysis of variance (anova) was used to analyze the influence of parameters (austenitizing temperature, percentage of nanoparticles, type of base media, nanoparticles type and soaking time) on the hardness, wear rate and impact energy properties of 420 martensitic stainless steel. the (anova) determines the relative significances of factors in expressions of their percentage contribution to the response[17].we can observe from the (anova) analysis (table(6) that the ranking of parameters according to its influence on the total variation on hardness, and wear rate properties were as follows: austenitizing temperature, type of base media, nanoparticles type, percentage of nanoparticles and soaking time was the least influence while for the impact energy were as follows: type of base media , austenitizing temperature , percentage of nanoparticles, nanoparticles type and last soaking time . table 6, results of the (anova). (hardness, wear rate and impact energy). hardness source df adjss adj ms f-value p-value % of contribution a 1 23835 23834.7 171.76 1.09e-06 46.02506 b 2 4809 2404.5 17.33 0.0012372 9.286114 c 2 10804 5402 38.93 7.537e-05 20.86238 d 2 7116 3558.2 25.64 0.0003316 13.7409 e 2 4112 2056.2 14.82 0.0020416 7.940217 error 8 1110 138.8 2.143395 total 17 51787 100 wear rate source df adjss adjms f-value p-value % of contribution a 1 3.16e-14 3.16e-14 135.07 2.74e-06 47.16418 b 2 6.4e-15 3.2e-15 13.61 0.002661 9.552239 c 2 1.23e-14 6.1e-15 26.26 0.000305 18.35821 d 2 1.03e-14 5.1e-15 21.98 0.000562 15.37313 e 2 4.6e-15 2.3e-15 9.8 0.007062 6.865672 error 8 1.9e-15 2e-16 2.835821 total 17 6.7e-14 100 impact energy source df adjss adjms f-value p-value % of contribution a 1 133.39 133.389 88.11 0.0000136 28.96634 b 2 76 38 25.1 0.000357 16.5038 c 2 134.33 67.167 44.37 0.0000468 29.17047 d 2 70.33 35.167 23.23 0.0004657 15.27253 e 2 34.33 17.167 11.34 0.0046238 7.45494 error 8 12.11 1.514 2.62975 total 17 460.5 100 where: df=degree of freedom, seq ss=sequential sum of square, adj ss=adjacent sum of square, adj ms=adjacent mean square, f=fisher’s test. 5.3. regression equation a regression model is developed using statistical software (minitab 18). regressions equation make correlations correlations between the significant terms acquired from (anova) analysis namely (austenitizing temperature, percentage of nanoparticles, type of base media, nanoparticles type and soaking time). abbas kh. hussein al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 112 (2019) 8 hardness (hv) = 458.50 36.39 a(oc )_985 + 36.39 a(oc )_1060 23.00 b(%)_0.01 + 9.50 b (%)_0.03 + 13.50 b(%)_0.08 0.67 c_deionized water 29.67 c_engine oil + 30.33 c_salt solution + 18.83 d_cuo + 8.67 d_tio2 27.50 d_α-al2o3 13.17 e(min)_50 8.00 e(min)_70 + 21.17 e(min)_90 … (5) wear= rate 1.3969e-07+ 4.191e-08a(oc )_985 0.000000 a(oc )_1060+ 2.603e-08 b(%)_0.01 8.25e-09 b(%)_0.03 0.000000 b(%)_0.08+ 6.98e-09 c_deionized water + 2.794e-08 c_engine oil 0.000000 c_salt solution 1.968e-08 d_cuo 1.397e-08d_tio2+ 0.000000 d_α-al2o3 + 1.651e-08 e(min)_50 + 5.08e-09 e(min)_700.000000 e(min)_90 … (6) impact= energy 51.833 + 2.722 a(oc )_985 2.722 a(oc )_1060 + 2.333 b(%)_0.01 + 0.333 b(%)_0.03 2.667 b(%)_0.08 1.500 c_deionized water + 3.833 c_engine oil 2.333 c_salt solution 2.333 d_cuo 0.167 d_tio2 + 2.500 d_α-al2o3 + 1.833 e(min)_50 0.333 e(min)_70 1.500 e(min)_90 … (7) 5.4. model summary from the graphs (4-a,4-b,4-c) shows that the data closely follow the straight lines, denoting a normal distribution. fig. 4. normal probability plot of residuals: a-hardness, b-wear rate and impact energy of 420 stainless steel). abbas kh. hussein al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 112 (2019) 9 also table (8) shows that (r2) approaches for this model very close to unity, and thus acceptable. it demonstrates that 97% approximately of the variability in the data can be explained by this model. thus, this model provides reasonably good explanation of the relationship between the independent factors and the response. table 7, model summary of (hardness, wear rate and impact energy). hardness wear rate impact energy s 11.7798 1.53e-08 1.2304 r-sq 97.86% 97.21% 97.37% r-sq(adj) 95.44% 94.06% 94.41% r-sq(pred) 89.15% 85.86% 86.69% 5.5. microstructural analysis from the micrograph that shows in figure (7) of samples quenched at different quenchants medium and tempered at (700°c) for (2 hours), it is noted that a microstructure consisting of full martensitic matrix with different ratios of un dissolved carbide dependent on heat treatment variables (austenitizing temperature, percentage of nanoparticles, type of base media, nanoparticles type and soaking time). steels with more than (0.2%) carbon and (1213%) chromium content consist of different volumes of (m3c, m7c3, and m23c6) carbide precipitate [18]. in this investigation, only (m23c6) carbides can be said to be identified due to the austenitizing and tempering temperatures used. as it is shows of the micrograph that shown in figure (7) and the(xrd) spectrum in figures (5,6) for samples austenitized at temperatures of (985 and 1060 °c) if we take it as examples of the heat treatments that were conducted, it clearly appears a reduction in intensity associated with a displacement to smaller angles. the peak displacement increases with increasing quenched temperature, showing the greater chromium carbides decomposition with temperature and the increased martensite saturation by carbon.getting (m23c6) carbide as a final consequence and decreasing it with increase of austenitizing temperature this explains increasing in hardness and decrease wear rate that can be attributed to increment of both chromium and carbon content dissolved in the martensite[19,20]. fig. 5. x-ray diffraction pattern of aisi420 martensitic stainless steel cooled of (0.08%αal2o3+engine oil) at 985 ºc for 90 min and tempered at (700°c) for (2 hours). fig. 6. x-ray diffraction pattern of aisi 420 martensitic stainless steel cooled of (0.03% αal2o3+engine oil) at 1060 ºc for 70 min and tempered at (700°c) for (2 hours). abbas kh. hussein al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 112 (2019) 10 fig. 7. optical microstructure of the specimens rank from (1 to 18) according to design of experiment that shown in table (2). 6. conclusions the approach of (taguchi‘s) robust design method to study hardness, wear rate and impact energy for 420 martensitic stainless steel led to conclude the following: 1-the taguchi method was successfully applied to determine the optimal values of austenitizing temperature, percentage of nanoparticles, type of base media, nanoparticles type and soaking time in order to maximize the hardness, impact energy and minimize wear rate. 2-the hardness value and impact energy value of the heat treated specimens were greater than that of untreated specimens and the wear rate was less for heat treated specimens. 3-from response table for (s/n ) ratio with respect to the hardness and wear rate we can marked on the most important factor where the ranking of factors as follows in terms of the proportion of their effect on hardness, and wear rate properties: austenitizing temperature (1060c˚), type of base media (salt solution), nanoparticles type (cuo), percentage of nanoparticles (0.08%)and soaking time(90min) was the least influence while for the impact energy were as follows: type of base media (oil), austenitizing temperature (985c˚), percentage of nanoparticles(0.01%), nanoparticles type (αal2o3) and last soaking time (50min). 7. references [1] a. rajasekhar,"heat treatment methods applied to aisi 431 martensitic stainless steels,"international journal of scientific & engineering research,vol.6,no. 4,pp.547553,2015. 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[19] a.n. isfahany and h. saghafian, and g. borhani.,"the effect of heat treatment on mechanical properties and corrosion behavior of aisi420 martensitic stainless steel," journal of alloys and compounds, vol.509, no.9, pp.3931-3936,2011. [20] j. g. gonzalezrodriguez, g. bahenamartinez and v. m. salinas-bravo," effect of heat treatment on the stress corrosion cracking behaviour of 403 stainless steel in nacl at 95°c," materials letters, vol.43, no.4, pp.208-214,2000. )2019( 112، صفحة 2د، العد15دجلة الخوارزمي الهندسية المجلم عباس خماس حسين 12 لصدأ مارتنسياتيلتأثير اختالف وسط التقسية على السلوك الميكانيكي لفوالذ مقاوم عباس خماس حسين* ليث قيس عباس** وسام ناجي حسن*** / الجامعة التكنولوجية/ العراق ** قسم هندسة المواد ,* /الجامعة التقنية الوسطى / العراق كوت / *** المعهد التقني www.abbas2000x@gmail.com:البريد االلكتروني * www.laithka2012@gmail.com:البريد االلكتروني ** www.weeesam1982@yahoo.com البريد االلكتروني: *** الخالصة (درجة المثلى للمعاملة الحرارية العوامل لتحديد تاغوتشي طة استخدام تقنيةاتصميم معاملة حرارية (اخماد ومراجعة) بوس هو الدراسة هذه من الغرض معدل البلى وطاقة ,الخواص (الصالدة لزيادة ) النقعنوع الجسيمات النانوية ووقت و نوع وسط األساسو النسبة المئوية للجسيمات النانوية االوستنايتحرارة لتصميم التجربة. عوامل العملية المثلى حددت باستخدام معيار )١٨l(تم اختيار مصفوفة متعامدة .٤٢٠المارتنسايتي أ الصدمة) لفوالذ مقاوم الصد )signal/noise( (األكبر هو األفضل) معيار بينماللصالدة وطاقة الصدمة )تم الحصول على مستويات األهمية البلى لمعدل كان) األفضل األصغر هو . الحرارية للمعاملة المتغيرات.)١٨(منتابباستخدام تحليل التباين المطبق بمساعدة برنامج معدل البلى وطاقة الصدمة,الصالدةخواص لعوامل العملية على للكسور الحجمية المئوية النسبة التوالي، على) دقيقة ٩٠ ، ٥٠،٧٠( النقع وأوقات ،) ˚١٠٦٠c ،˚c ٩٨٥( األوستنايت حرارة درجة (اخماد) كانت ) 3o2al-α،2tio،cuo) تم تحضيرها من خالل تشتيت جسيمات نانوية التي هي (%٠٫٠٨و٣٠٫٠،٠١،٠( بثالثة مستويات مختلفةللجسيمات النانوية أظهرت.لساعتين بعد االخماد بالموائع النانوية ˚c)٧٠٠( العينات بدرجةتم مراجعة بأوساط أساسية (الماء غير المتأين، محلول الملح، زيت المحرك). ١٠٦٠االوستنايت (درجة حرارة : تياال النحو وفق على الصالدة ومعدل البلى تأثيرها على الخواص نسبة حيث من العوامل ترتيب (s/n )النتائج لنسب c˚ ,()( نوع الجسيمات النانوية ,)محلول ملحينوع وسط االساسcuo(, )بينما )%0.08( النسبة المئوية للجسيمات النانوية واخيرادقيقة) ٩٠وقت النقع ، )3o2al-α( نوع الجسيمات النانوية، )c˚٩٨٥االوستنايت (درجة حرارة ,)زيت المحركنوع وسط االساس( :تياال النحو وفقلطاقة الصدمة كانت على .دقيقة) ٥٠وقت النقع ( واخيرا )%٠١.٠( النسبة المئوية للجسيمات النانوية (microsoft word \317 \323\307\343\355 \346\321\343\322\3551017) al-khwarizmi engineering journal al-khwarizmi engineering journal,vol. 13, no. 3, p.p. 1017 (2017) numerical investigations on heat flow of nanofluids in ribs tube configurations sami d. salman* ramzi ata abd alsaheb** *,** department of biochemical engineering/ al-khwarizmi college of engineering/ university of baghdad *e-mail :sami.albayati@gmail.com **e-mail: ramzi_eng_1981@yahoo.com (received 20 june 2017; accepted 24 july 2017) https://doi.org/10.22153/kej.2017.07.002 abstract in this paper presents two dimensional turbulent flow of different nanofluids and ribs configuration in a circular tube have been numerically investigation using fluent 6.3.26. two samples of cuo and, zno nanoparticles with 2% v/v concentration and 40 nm as nanoparticle diameter combined with trapezoidalribs with aspect ratio of p/d=5.72 in a constant tube surface heat flux were conducted for simulation. the results showed that heat flow as nusselt number for all cases raises with reynolds number and volume fraction of nanofluid, likewise the results also reveal that zno with volume fractions of 2% in trapezoidal ribs offered highest nusselt number at reynolds number of re= 30000. keyword: heat transfer augmentation, friction factor, thermal performance factor, ribs configuration, cfd simulation, fluent. 1. introduction heat exchangers as convective heat transfer equipment are widely used in various engineering applications. heat rate enhancement in all types of heat apparatus is one of the great significance for the industry. besides the energysaving, it also leads to minimize the size and weight. in general, the enhancement techniques may be categorized into two kinds; first one is the active techniques which required an external power and second one is the passive techniques which do not required an external power source. several attempts on heat augmentation techniques using roughen surfaces or tabulators such as groove and rib to disturb the flow and break the thermal boundary layer and consequently increase the heat transfer coefficient. different configuration of channels with rib– grooves had been investigated in the antecedent decades considering different combinations of the ribs configurations and temperature gradients. the ordinary ribsgeometries including circular rectangular, square and triangular, all these geometries of channels with rib–grooves were utilized in various engineering applications; gas turbines heat exchanger with cross-flow, aircooling system and gas cooled nuclear power reactor [1]. on the other hand, nanofluidsas heat transfer enhancement technique has bring significant interesting the past years as applicable and alternative coolants for many fields such as power generation, automotive electronics, air conditioning and nuclear applications [2]. different types of nanoparticles have been utilized for nanofluid preparation, including metals such as silver (ag), copper (cu), gold (au), and also metal oxides such as fe3o4,tio2,cuo and al2o3[3–9]. due to their sufficient low cost, metal oxides are more enticing for heat transfer augmentation applications compared to metals. simultaneously, nanofluids were combined with other heat transfer enhancing techniques [10, 11, and 12]. ahmed et al. [10], reported numerical simulation of the heat and friction characteristics of copper/water nanofluid with various volume sami d. salman al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 1017 (2017) 11 fraction range (0 to 0.05)through isothermally heated corrugated channel under laminar flow condition ( re = 100-1000).it was found that the heat transfer augmented as nanoparticle volume fraction of increases. likewise, the pressure drop somewhat increases with the volume fraction increases, for all reynolds number. in addition, the highest value in heat transfer enhancement was obtained at re= 200 and 5% v/v nanoparticle with 43.9% enhancement compared with base fluid. mohammed et al. [11], has conducted numerical study on the turbulent heat transfer and friction factor of different nanoparticles cuo, al2o3,zno and sio2, with different concentration (1% to 4% ) and different nanoparticle size (25 nm to 80 nm), with different base fluids (glycerin, water, engine oil) in channel with rib–groove. their results showed that sio2-glycerin produce highest nusselt number followed by sio2engine oil while sio2water produce the lowest value of nusselt number. salman et al. [12] reported a numerical simulation on heat transfer enhancement of nanofluids in circular micro tube using different nanoparticles cuo, al2o3, zno and sio2, with different concentration (1% to 4% ) and different nanoparticle size (25 nm to 80 nm with ethylene glycol base fluid. their results showed that sio2nanoparticles with particle size (dp) of 25 nm and particle concentration 4% at re = 1500 gives the highest value of nusselt number. it is evident from the recent studies that the simultaneous use of turbulators with nanofluids efficiently gives further improvement in heat transfer rate as compared with the individual uses of nanofluids or of ribs configuration. in the present research the effects of two types of nanoparticles; cuo and zno with 2% volume fractions and nanoparticles size of 40nmwith reynolds number ranging from 10000 to 30000in constant tube surface heat flux with trapezoidal ribs configurations have been investigated numerically. 2. numerical model 2.1. geometry model and the governing equations two dimensions of governing equations have been used to characterize the fluid flow and heat transfer in the circular tube with different ribs configurations as shown in figures1a-b.the diameter of tube d=10mm and length of rib tube l2=100mm and the high and width of ribs is h=1.2mm and w=1.2mm respectively. the pitch of ribs is p=10mm.the entrance tube length l1=50mm in order to achieve the fully develop flow in the tube. (a) (b) fig. 1. schematic diagram of (a) tube geometrical model, (b) trapezoidal ribs. the assumptions below have been adopted for numerical simulation: (i) nanofluid is considered as newtonian and incompressible fluid, (ii) flow is turbulent, (iii) heat flux is constant with negligible radiation effects (iv) nanoparticles is regarded as spherical shape and nanofluid is used as single phase model (v) the rmophysical properties of nanofluidsare considered as constant values. the governing equations in cartesian form are illustrated as follows [13]: equation of mass conservation: sami d. salman al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 1017 (2017) 12 0 u v x y ∂ ∂ + = ∂ ∂ …(1) equation of momentum conservation: 2 2 2 2 1 ( )eff eff pu v u u u v x y x x y µ ρ ∂∂ ∂ ∂ ∂ + = − + + ∂ ∂ ∂ ∂ ∂ …(2) 2 2 2 2 1 ( ) eff eff pu v v v u v x y y x y µ ρ ∂∂ ∂ ∂ ∂ + = − + + ∂ ∂ ∂ ∂ ∂ …(3) equation of energy conservation: 2 2 2 2 ( )eff eff eff eff kt t t t u v x y cp x y ∂ ∂ ∂ ∂ + = + + ∂ ∂ ∂ ∂ µ ρ …(4) 2.2. simulation boundary conditions various inlet velocities in the tube with constant temperature (t=300 k) and constant heat flux (200,000 w/m2) were used for simulation. 2.3. nanofluids thermophysical properties the physical properties of nanofluids for cuo and zno nanoparticles are estimated using the following equations [14] and [20]: (1 )n f f np= − +ρ ϕ ρ ϕρ …(5) ( ) (1 )( ) ( )nf f npcp cp cp= − +ρ ϕ ρ ϕ ρ …(6) where��,���are densities of the base fluid and nanoparticles, ϕ represents volume fraction of nanoparticle,�������and ������ are heat capacities of nanoparticles and base fluid,respectively. ef f b row nian s tatick k k= + …(7) ( 2 ) 2 ( ) ( 2 ) ( ) np f f npstatic f np f f np k k k kk k k k k k  + − − =   + + +   φ φ …(8) 50000 ( , ) 2 b brownian f f np np k t k cp f t r = ϕρ β ϕ ρ …(9) where; ( , ) (0.28217 0.003917) (0.03669 o t f t t   ϕ = + + ϕ 0.00339112)    − t is the fluid temperature, k is the boltzman constant and t0 is the reference temperature, β values of two types nanoparticles with their boundary conditions are illustrated in table 1. table 1, β values of of cuo and zno nanoparticles material [14]. nano particles β concentration temperature (k) cuo 0.9446 9.881(100 ) − φ 1% ≤ ϕ ≤ 6% 298 ≤ t ≤ 263 zno 1.07304 8.4407(100 ) − φ 1% ≤ ϕ ≤ 7% 298 ≤ t ≤ 263 the effective viscosity can be obtained by using the following mean empirical correlation [15]: 1.03 0.3 1 (1 34.87 ( /6 ) ) eff f fo dpn m − = − µ µ ϕ πρ …(10) where; m is the base fluid molecular weight, n is the avogadro number ρfo base fluid density 2.4. grid testing and codes validation finite volume was used to solve the equations of continuity, momentum and energy with their corresponding boundary conditions. the turbulences model was very important to describe the flow characteristics for each application. the standard k-ε turbulence model and the renormalized group (rng) k-ε turbulence model were selected in order to reach accurate prediction for simulation. the navier-stokes equations with time-independent for incompressible turbulence model were solved for analysis. the simple algorithm was selected to evaluate the pressure field, the velocity profile at the inlet assumed as fully developed and the inlet turbulence intensity was selected as 1%. three different mesh spacing sizes (0.01,0.02,0.03) was selected for grid size effect on nusselt number values at 10000 reynolds number including plain tube and trapezoidal ribs tube configurations. the results sami d. salman al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 1017 (2017) 13 show that the mesh spacing of 0.01 give the optimum values of nusselt number with maximum deviations up to 3% as elaborated in the table 2. table 2, mesh dependence configuration mesh spacing size % nudeviations % 0.01 0.02 0.03 0.02 0.03 plain tube 89 87 86 2% 3% trapezoidal ribs tube 115 113.5 111 1% 3% 3. results and discussion 3.1. local and average nusselt number the variations of the local nusselt number versus position x-direction of top wall and average nusselt number for circluar tube with trapezoidal ribs and reynolds number ranging from 10000 to 30000 using water as a working fluidare shown in figures 4 and 5.its be noted that the nusselt number increases with the increase of the reynolds number and the highest nusselt number obtained at reynolds number of 30000. this implies that the use of the ribs in the circular tube produce (i) good turbulence flow with good mixing after the ribs leading to thermal boundary layer desolation and (ii) the strong flow vortices conducte better mixing between the fluid near the tube wall and the tube center. the highest heat transfer enhancement was achieved for the trapezoidal ribs due to the increase of strong turbulence intensity. fig. 4.varation of local nusselt number with xposition with trapzoidal ribs fig. 5. variation of average nusselt number with trapezoidalat different reynolds number. 3.2. skin friction factor the friction coefficient variations with reynolds number for trapezoidal of ribs is presented in figure 6. from this figure it is clearly seen that the skin friction factor constrict with reynolds number the rises and maximum value of skin friction coefficient can be achieved by using trapezoidal ribs, whereas the minimum values of friction coefficient was found for smooth tube. x(m) l o c a l n u ss e lt n u m b e r 0.06 0.075 0.09 0.105 0.12 0.135 0.15 100 150 200 250 300 350 400 450 re=30000 re=25000 re=20000 re=15000 re=10000 sami d. salman al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 1017 (2017) 14 fig. 6. variation of skin friction coefficient with trapezoidal at different reynolds number. 3.3. the effect of nanoparticles two types of nanoparticles namely cuo and zno with 2% volume fraction and pure water as base fluid for trapezoidal ribs were used in this investigation. the nusselt number and skin friction friction versus different reynolds number are shown in figure.7 and 8.from figure 7, its clearly noticed that the nanofluid nusselt number was higher than that obtained by base fluid (water), this is result in due to the presence of nanoparticles increase of thermal conductivity and due to nanoparticles collision oneself and between the tube wall and nanoparticles, which increase the energy rate exchange. among test fluids, it is clearly noted that zno nanofluid offered highest nusselt number, followed by cuo and pure water, respectively. this is due to the lower thermal conductivity of zno as compared with cuo nano fluids, from figure 8, its clearly seen that the friction factor decreases with the rising of the reynolds number, while no effect was distinguish with different nanofluids. fig. 7. variation of average nusselt number for pure water and different nanofluids types with trapezoidal ribs. fig. 8. skin friction factorvariation of for pure waterand different nanofluids types with trapezoidal ribs 4. conclusions forced convection for turbulent flow heat transfer simulation in a constant heat flux tube with trapezoidal ribs configurations were carried out using fluent 6.3.26.the effect of this configuration with aspect ratio of p/d=5.72 with water, cuo and, zno nano fluids with 2% volume fractions as a single-phase model were reported for reynolds number variation from 10000 to 30000. the results in forms of heat transfer coefficient (nu) and skin friction factor (f) are reported as follow; • the local and average nusselt number are augmented for trapezoidal ribs tube than that of the plain tube and maximum nusselt number was obtained with reynolds number equal to 30000, while the maximum friction factor obtained at reynolds number equal to 10000. • the zno nanofluid gives highest values of nusselt number and skin friction factor, followed by cuo and pure water gives the lowest values of nusselt number. however no effect was distinguish with different nanofluids and pure water. sami d. salman al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 1017 (2017) 15 nomenclature keff thermal conductivity in energy equation, w/m k re reynolds number, dimensionless nu nusselt number, dimensionless p pressure, n/m2 u velocity m/s t temperature. °c. greek symbols ρ density, kg/m3 eff τ uuur stress, n/m2. acknowledgment we wish to specially acknowledge the assistance offered by the university of baghdad al khwarizmi college of engineering for carrying our this investigation. 5. references [1] o. manca, s. nardini, d. ricci, a numerical study of nanofluid forced convection in ribbed channel, applied thermal engineering 37 (2012) 280–292. [2] m. chandrasekar, s. suresh, a. chandra bose, experimental studies on heat transfer and friction factor characteristics of al2o3/water nanofluid in a circular pipe under laminar flow with wire coil inserts, experimental thermal and fluid science 34 (2010) 122–130. [3] c.y. tsai, h.t. chien, p.p. ding, b. chan, t.y. luh, p.h. chen, effect of structural character of gold nanoparticles in nanofluid on heat pipe thermal performance, materials letters 58 (2004) 1461–1465. [4] m.s. liu, m.c. lin, c.y. tsai, c.c. wang, enhancement of thermal conductivity with cu for nanofluids using chemical reduction method, international journal of heat and mass transfer 49 (2006) 3028–3033. [5] e. tamjid, b.h. guenther, rheology and colloidal structure of silver nanoparticles dispersed in diethylene glycol, powder technology 197 (2010) 49–53. [6] s.m.s. murshed, k.c. leong, c. yang, enhanced thermal conductivity of tio2water based nanofluids, international journal of thermal sciences 44 (2005) 367–373. [7] h. zhu, c. zhang, s. liu, y. tang, y. yin, effects of nanoparticles clustering and alignment on thermal conductivities of fe3o4aqueous nanofluids, applied physics letters 89 (2006) 1–3. [8] j.a. eastman, s.u.s. choi, s. li, l.j. thompson, enhanced thermal conductivity through the development of nanofluids, proceedings of the symposium on nanophase and nanocomposite materials ii, vol.457, materials research society, usa, 1997, pp. 3–11. [9] m.e. meibodi, m. vafaie-sefti, a.m. rashidi, a. amrollahi, m. tabasi, h.s. kalal, simple model for thermal conductivity of nanofluids using resistance model approach, international communications in heat and mass transfer 37 (2010) 555–559. [10] m.a. ahmed, n.h. shuaib, m.z. yusoff, a.h. al-falahi, numerical investigations of flow and heat transfer enhancement in a corrugated channel using nanofluid, international communications in heat and mass transfer 38 (2011) 1368–1375. [11] h.a. mohammed, a.n. al-shamani, j.m. sheriff, thermal and hydraulic characteristics of turbulent nanofluids flow in a rib–groove channel, international communications in heat and mass transfer 39 (2012) 1584–1594. [12] b.h. salman, h.a. mohammed, a. sh. kherbeet, heat transfer enhancement of nanofluids flow in microtube with constant heat flux, international communications in heat and mass transfer 39 (2012) 1195– 1204. [13] m. corcione, heat transfer features of buoyancy-driven nanofluids inside rectangular enclosures differentially heated at the sidewalls, international journal of thermal sciences 49 (2010) 1536–1546. [14] r.s. vajjha, d.k. das, “experimental determination of thermal conductivity of three nanofluids and development of new correlations”, international journal of heat and mass transfer, vol. 52, issues 21–22, pp. 4675–4682, 2009. [15] m. corcione,”heat transfer features of buoyancy-driven nanofluids inside rectangular enclosures differentially heated at the side walls”, international journal of thermal sciences, vol. 49, issue 9, pp. 1536–1546, 2010. sami d. salman al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 1017 (2017) 16 [16] jung-yang san (2006), wen-chieh huang “heat transfer enhancement of transverse ribs in circular tubes with consideration of entrance effect” international journal of heat and mass transfer 49 p 2965–2971 [17] maiga, s. e. b., s. j. palm, c. t. nguyen, g. roy and n. galanis (2005). "heat transfer enhancement by using nanofluids in forced convection flows." international journal of heat and fluid flow 26(4): 530-546. [18] usui, h., y. sano, iwashita, k. &isozaki, a. 1996. enhancement of heat transfer by a combination of internally grooved rough tube and twisted tape. international chemical engineering 26(1): 97-104 )2017(10-17 ، صفحة 3د، العد13دجلة الخوارزمي الهندسية المجلم سامي داود سلمان 17 اتءالنتو ينبوب ذاألفي للموائع لتدفق الحراري لعددية دراسة **عبد الصاحب سامي داود سلمان* رمزي عطا / جامعة بغدادالخوارزمي الهندسة كلية /األحيائية كيميائيةالقسم الهندسة *،** sami.albayati@gmail.com :البريد اإللكتروني* ramzi_eng_1981@yahoo.comااللكتروني:**البريد الخالصة fluentبرنامجعدديا باستخدام األبعاد ةثنائيات ءنتوال يتم دراسة تأثيرالجريان المضطرب للموائع النانوية في انبوب دائري ذالبحث في هذا فيالنانوية نانومتر قطر الجسيمات ٤٠و ٢%كأوكسيد الزنك وأوكسيد النحاس بتركيز حجمي يصل الى الجسيمات النانوية أستخدام نموذجين تم. 6.3.26 لحرارة السطحية للمحاكاة. وأظهرت ثابت ل تدفقتحت p / d = 5.72 تصل الى الى قطر األنبوب ءطول ضلع النتوشبه منحرف نسبةنتوؤات بشكل يانبوب ذ بتركيز كسيد الزنك والنتائج أيضا أن أ كما أظهرتللموائع النانوية حجميالبتركيز رينولدز وزداد بزيادة نسلت لجميع الحاالت ي احرارة عددالنتائج أن تدفق ال نسلت العدد لفي األضالع شبه منحرف عرضت أعلى ٪٢مع حجم الكسور من أعلى قيمة في انبوب ذو نتوؤات بشكل شبه منحرف ٢حجمي يصل الى % .٣٠٠٠٠ الىرينولدز عدد عندما يصل (microsoft word 9282\346\323\307\343 \346\343\325\330\335\354) al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 14, no. 2, june, (2018) p.p. 9282 sculptured surface design and implementation by lofting design method using cross-sectional b-spline curves wisam kadhum hamdan* mustafa mohammed abdulrazaq** *, ** department of production engineering and metallurgy / university of technology *email: wisamuot@yahoo.com **email: mustafaalneame@yahoo.com (received 8 march 2017; accepted 20 november 2017) https://doi.org/10.22153/kej.2018.11.004 abstract this research presents a particular designing strategy for a free form of surfaces, constructed by the lofting design method. the regarded surfaces were created by sliding a b-spline curves (profile curves), in addition to describing an automatic procedure for selective identification of sampling points in reverse engineering applications using coordinate measurement machine. two models have been implemented from (ureol material) to represent the different cases of b-spline types to clarify its scope of application. the interior data of the desired surfaces was designed by matlab software, which then were transformed to ug-nx9 software for connecting the sections that were designed in matlab program and obtaining g-code programs for the models in addition, a virtual machining process was simulated to show the machining pitfalls, using vericut software. the samples were machined using 3-axis vertical cnc machine (isel) type. finally, the samples were measured using faro arm (cmm inspection) and it was found that the average of errors was equal to (0.0589 mm) for the cross-sectional uniform b-spline model, and (0.1337 mm) for the lofted non-uniform b-spline model. it can be concluded that the whole steps task which built in the present research can be programmed in a single block of the part program where any surface at minimum designing time can be created from it. keywords: b-spline, cmm, , lofted method, sculptured surface. 1. introduction the impact of globalization on business has forced most industries to become more innovative and implement newer strategies. in the aerospace automobiles, and many industry appliances, and different practical purposes sculptured surfaces are pertaining with designers and engineers to perform the required representation of the products. the milling of such complicated topologies is a main issue in cam since the availability of nc machining, by their programs, to linear and circular movements [1,2]. also, from reverse engineering which is a method utilized in the planning stage for a new products, can be depending on it to improve the design of any surfaces or it can be create a new surfaces depending on the original surface. lofting is a modeling technique that fits a surface through a series of curves and builds the required topology for the resulting surface. lofting can be used to create closed bodies as well as the open bodies [3]. the lofted surface is a two-parameter parametric function s (u, v); the curves provide the u parameter of the surface and the lofting algorithm defines the v parameter [4] the researchers' studies present a various methods in reverse engineering. many of these studies are depend on the analyzing of points cloud gained by coordinates measuring equipment, like (cmm) coordinates measuring machine, optical scanner or interferometry wisam kadhum hamdan al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 8292 (2018) 83 system. one of them was h. park (2004) who introduced a novel method to fix the issue of interpolation the b-spline surfaces to set of contours, by varying the numbers of points from contour to another. his method implies a new manner of obtaining a serial of coincident bspline curves from the obtained contours. the method is depend on universal parameterization, that allows the knots to be taken freely but that gives the b-spline curve interpolation more linear system stability. since the numbers of control point in the coincident b-spline curves equals to the largest numbers of contour point [5]. ken yano and koichi harada (2010) gave a new approach by skinning the generated cylindrical meshes for reconstructing b-spline surfaces. their approach is usable only for generalizing cylindrical meshes, and there are numerous real objects which can be reconstructed and modeled by skinning the cylindrical meshes [6]. this research presents a particular designing strategy for a free form of surfaces, constructed by the lofting design method created by sliding b-spline curves. 2. b-spline curves modeling and constructing a b-spline curve differs from other modeling techniques such as bezier or hermite curve, where it generally consisting of more than one segment made up the curve. the segments are affected by only a few control points, which are the coefficient of b-spline basis function polynomials. the curve degree is independent of the total number of control points. these characteristics allow changes in shape that do not propagate beyond one or only few local segments. the main formula that represents b-spline curve in term of their blending functions is [7]: (1)… )()( , 0 unpup kii n i  = = where (pi) is the control points and (ni, k) representing the appropriate basis function for bspline representation. for b-spline curves, the variable (k) controls the degree of basis polynomial, which is independent of the numbers of control points. the basis function (ni, k) is defined by following recursive equation [7]: 11, 1)( + ≤≤= iii tutifun …(2) = 0 otherwise and: 1 1,1 1 1, , )()()()( ++ −++ −+ − − − + − − = iki kiki iki kii ki tt unut tt untu n ... (3) the (ti) represents the knot values, and a set of knot values comprises a knot vector (t). the knot vector has a significant influence on the blending function ni, k (t) and theory on the b-spline curve itself. since the knot vector values effecting on bspline shapes, that classified b-spline curves into periodic and non-periodic b-spline curves [8]. 2.1. uniform b-spline curves many geometric modeling situations do not require the curve to pass through the end points. the uniform b-spline curves is a piecewise polynomial curves controlled by a serial of points which the curves usually doesn't interpolates the end points. this method produces with a uniform or periodic knot vector, the basis functions repeating itself through successively interval for the parametric variables. the final equation of cubic periodic (uniform) b-spline curve when k4 is [9]: p(u) = u * mb * p ... (4) …(5) the initial data generated the required curves; the proposed programs represent the curves in a graphically with the help of matlab programming system. figure (1) illustrates the designing of a single and series cubic b-spline curves blended with each other to build the entire section of the closed b-spline curves. (a) ]1[ 6 1 )( 23 uuuup =             − − −− 0141 0303 0363 1331 ` 3 2 1 0             p p p p wisam kadhum hamdan al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 8292 (2018) 84 (b) fig. 1. construction of uniform cubic curves: (a) single curve, (b) series of curves. 2.1 non-uniform b-spline curves non uniform b-spline curve solves the problem of interpolating the curve with the vertices of control points, making it the preferred method in design, especially for the open parts where the uniform b-spline shows a deficiency in representation. the non-uniform b-spline curve consisting of number of segments depends on the value of the (n) and (k) variables in both directions of the vectors (u, w). for a non-uniform b-spline curve that interpolates the end points, the (ti) in eq. (3) is [10]: …(6) as a result of compensation the variables in eq.(3) the basis functions that generate multiple segments, each one is different from the other but complement each other. for example the curve has two segments with (n=4, k=4), and it has three segments with (n=5, k=4). figure (2) illustrates these cases of non uniform b-spline curve. (a) (b) fig. 2. non uniform b-spline curves, (a) (n=4, k=4), (b) (n=5, k=4) 3. create the sections of b-spline curves in the proposed work the lofting technique that used in the present work have been produced using the method of cross-sectional design concept. the models are generated through fits a surface through a series of curves and build the required topology for the resulting surface. two models have been designed to represent the different cases of b-spline types to clarify its scope of application. the first one created for representing the closed bodies using the uniform b-spline curves and the reason of that is the other type of b-spline curve (non-uniform) leads to generate a state of discontinuity at meeting the first and last points of polygon of control points, that’s making the uniform b-spline curves as the preferred type for modeling such kinds of closed bodies. niifknt i >+−= 2 nikifkit i ≤≤+−= 1 kiift i <= 0 wisam kadhum hamdan al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 8292 (2018) 85 on the other hand the second model have been designed to representing the open bodies modeling using the non-uniform b-spline curves because of the uniform type doesn’t interpolate the end points of the control polygon which made a limitations in representation such surfaces like open profiles. generally both of the models had twoparameter parametric function s (u, v); the curves provide the u parameter of the surface and the lofting algorithm defines the v parameter. using the programming language in matlab program, curves are designed of different types of b-spline curves by building algorithms including the basis functions matrices for each type as illustrated in figure (3). (a) ) (b) fig. 3. the proposed sectional curves, (a) closed uniform b-spline curves, (b) open non-uniform bspline curves there are no any embedded functions in this software dedicated for the construction of the bspline curves. accordingly, special sub-routines have been implemented to construct the b-spline curves. implementing the program to build the bspline surface needs drawing the block diagram which is shown in figure (4). fig. 4. flowchart of the proposed program for building b-spline curve 4. skinning the sectional curves and generating tool paths for the models the cad module, where profile of the curves generating the surfaces which are modeled-using matlab, transferred to the ugs-nx9-through txt data-exchanges file to view the required shape. after the construction of the b-spline curves, the data of each curve has been represented and saved in a single matrix of (n x 3), where n is the number of rows which is equal to n =1+ � ∆� , where ∆u is the increment of the wisam kadhum hamdan al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 8292 (2018) 86 independent parameter. each matrix is saved as (txt) file and exported to the ug-nx program. each imported curve has been opened individually in the ug-nx program. after importing each curve, a skinning procedure is to be followed converting these curves to a surface using the following steps. figure (5) illustrates the importing cad data to ug-nx9 software after skinning the sectional curves for the both models. (a) (b) fig. 5. lofted surfaces after skinning, (a) closed curves model (section of bone profile), (b) open curves model (mouse profile). 4.1 tool path generation and simulation utilizing ug-nx after the completion of representing cad models, it is followed by the process of generating the tool paths for designed part using ug-nx software. basing on the two phases of the process, the first phase is creating tool paths for the rough milling, where the characteristics must be chosen for this kind of machining, such as (machining method, path strategies, tool shapes, tool diameters, feed rates …etc.). the second phase is creating tool path for finish machining. in order to generate tool path for the models, flat-end tool with diameter (8mm) have been used for rough machining. since the aim of roughing is removing massy amounts of material, the value of step over in this stage will be higher than its value in finishing, which is approximately equal to five times of finishing step over value. figure (6) shows the two processes of machining for first model of the closed b-spline curves (section of bone profile), in addition to the second model that represents the lofted surface of open non-uniform b-spline curves (mouse profile). (a) (b) fig. 6. simulation of verifying tool path for the two models, (a) rough machining, (b) finishing process. 4.2 tool path verification the verification process has been done for the generated tool path using vericut software to detect the errors of nc program before loading the program on the cnc machine. g-code files imported to vericut software and a virtual machine has been designed to verify the tool path, and checking the machining pitfalls, as shown in figure (7). fig. 7. progress simulation of machining using vericut software insert urface through curves mesh surface wisam kadhum hamdan al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 8292 (2018) 87 5. experimental work the machining process has been conducted on models from ureol material, with different dimensions of the primary blocks as follows: 1. closed lofted model (uniform b-spline curves): x= 50 mm, y= 50 mm, z= 75 mm 2. open lofted model (non-uniform b-spline curves): x= 80 mm, y= 100 mm, z= 80 mm. 5.1 cnc milling machine milling processes have been performed on a vertical 3-axis cnc milling machine "isel type" in the institute for machine elements, design and manufacturing in tu bergakademie freiberg in germany, as illustrated in figure (8). the characteristics are given in table (1), to achieve the milling process for the models that have been designed. fig. 8. 3-axis cnc machine (isel type) table 1, characteristics of cnc milling machine 5.2 machining cutters two kinds of milling tool are utilized in the proposed work research: 1flat-end mill tool with (ø 8 mm) dia. and four flute cutters, made from (hss) high-speed steel have been utilized for roughing. 2ball-end mill tool with (ø 8 mm) dia. made from (hss) for finishing. fig.(9) shows the two types of cutting tools. fig. 9. cutting tools used for machining 5.3 surface machining the machining operations are executed in two processes; rough milling and finishing. removing materials occurred in rapid way as much as possible during rough milling. the tool removed the materials in layers till the surface is encountered. large amounts of material removal rate in rough machining are utilized to minimizing the process time. the rough milling occurred in parallel layers till access the required depths. the fineness of result surfaces in roughing is not significant as layers of material which left for finishing. figure (10) shows the two passes roughing and finishing for machined the first part and figure (11) clarify the two phases for the second part. (a) (b) fig. 10. machining process for (section of bone profile), (a) roughing, (b) finishing features of cnc milling machine icp 4030 traverse path x/y/z [mm] 400 x 300 x 140 software pro nc repeatability [mm] ± 0.02 controller 500w power supply unit with processor board process speed x/y/z [mm/s] 100 drive motors stepper motors dimensions w × d × h [mm] 780 × 850 × 810 throughput [bit/s] 170 wisam kadhum hamdan al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 8292 (2018) 88 (a) (b) fig. 11. machining process for (mouse profile), (a) roughing, (b) finishing 6. measurement and inspection the measurement process have been implemented using faro-arm which is a portable (cmm) coordinates measuring machine that gives an easy products verifications for the manufacturers to assessment the quality by making 3d inspection, cad comparisons, dimensional analyzing, and reverse engineering. this arm consists of 6 degrees of freedom which facilitate the measurement process. figure (12) shows the measuring arm. fig. 12. faro arm (cmm). after machining, the measurement process has been conducted for the manufactured parts. the aim of testing these parts is to ensure that the product is manufactured with high precision, and to find out the differences between the cad models which have been designed and the parts after the manufacturing process. depending on the results of measuring, there will be evaluation of designing methods to see its feasibility success. 6.1 measurement of the closed lofted surface (section of bone) the measurement of each product (cam model) can be conducted by scanning the entire products surface through passing the ball of the faro arm over the whole surface. after measurements, the faro cam2 measure software imports design files in (iges) format which contain the coordinate of each scanned points. figure (13) illustrates the comparison process for the first model surface. (a) (b) fig. 13. comparing between cad and cam models of the closed lofted surface, (a) cad model in (farocam2 software), (b) scanning on real part. after completion of measurement scheme, the program provides report, explains the details of the measurement and refers to the amount of error incident. figure (2) shows a sample of measuring data for the first part. wisam kadhum hamdan al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 8292 (2018) 89 fig. 14. sample of measuring data for the closed lofted part in addition to the measuring data, it provides the values of some constants and variables such as the average of error and standard deviation. average of error ��� � ∑ �� � …(7) standard deviation ��� � �∑������� � …(8) where: xi= error values, n= number of errors. table 2, the average error, standard deviation and maximum error for the first model. 6.2 measurement of open lofted surface figure (15): shows the comparison of cad models and real part of the lofted surface, and figure (16) shows sample of measuring data for the second part (mouse profile). fig. 15. comparing between cad and cam models of the open lofted surface. the average error 0.0589 mm standard deviation 0.0713 mm maximum error 0.1827 mm wisam kadhum hamdan al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 8292 (2018) 90 fig. 16. sample of measuring data for the open lofted part. the big red arrow refers to exceeding the measured error to the given value of tolerance. on the other hand, the small yellow arrow refers to approach the value of measured error to the given tolerance. table 3, the average error, standard deviation and maximum error for the open lofted surface. 7. conclusion • the design methodology of lofted b-spline surface does not effect on the manufacturing result. the agreement for this concluding remark is the maximum produced error for closed b-spline model and the open lofted bspline model are (0.1827) mm and (0.1912) mm respectively. • the first segment of the non-uniform b-spline surface start with the polygon of control points, however it doesn't end with it, in opposite to the last segment which is end with the polygon of control points but it doesn't start with it. • in spite of the limitation of interpolating the uniform b-spline curve with the polygon of control polygon, however it considered an advantage for representing the closed parts, because using the non-uniform b-spline curves leads to generate a state of discontinuity at meeting the first and last points of polygon of control points. contrarily of representing the open parts which depends on the non-uniform type. • the method has been implemented on various types of sculptured models. looking at the given result, it is possible to say that this method has a good level of applicability in automated scansion systems the average error 0.1337 mm standard deviation 0.0414 mm maximum error 0.1912 mm wisam kadhum hamdan al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 8292 (2018) 91 8. reference [1] r. j. yan, j. wu, j. y. lee, c.-s han“ a novel method for 3d reconstruction: division and merging of overlapping b-spline surfaces, computer-aided design, 2016 . [2] sotiris, andreas c., “a cnc machine tool interpolator for surfaces of cross-sectional design”, robotics and computer-integrated manufacturing, 2006. [3] h. park, h. b. jung, k. kim "a new approach for lofted b-spline surface interpolation to serial contours" int j adv manufacturing technology 2004. [4] k. r. koch "identity of simultaneous estimates of control points and of their estimates by the lofting method for nurbs surface fitting" the international journal of advanced manufacturing technology, 2009. [5] h. park, "an approximate lofting approach for b-spline surface fitting to functional surfaces" int j adv manufacturing technology 2001. [6] ken yano & koichi harada "reconstruction of b-spline skinning surface from generalized cylinder mesh" the visual computer, volume 26, no. 1, 2010. [7] d. auger, q. wang, j. trevelyan, s. huang & wei zhao “investigating the quality inspection process of offshore wind turbine blades using b-spline surfaces” measurement, 2017. [8] y. zhang, j. cao, z. chen, x. li & x. zeng," b-spline surface fitting with knot position optimization”, computers & graphics, 2016. [9] y. yamaura, t. nanya, h.imoto & t. maekawa," shape reconstruction from a normal map in terms of uniform bi-quadratic b-spline surfaces”, computers & graphics, 2015. [10] y. zhang, j. cao, z. chen, x. li & x. zeng," b-spline curve fitting with invasive weed optimization”, applied mathematical modelling, 2017. )2018( 82-92، صفحة 2د، العد14دجلة الخوارزمي الهندسية المجلم وسام كاظم حمدان 92 ة لمنحنيـاتتعرضللمقاطـع المس ميمالتص ح الحـرة بأسـتخدام طريقةذ االسطـميم وتنفيـتص spline-bالـ ** الرزاقمصطفى محمد عبد *وسام كاظم حمدان الجامعة التكنولوجية / هندسة االنتاج والمعادنقسم *,** wisamuot@yahoo.com*البريد االلكتروني: mustafaalneame@yahoo.com**البريد االلكتروني: خالصة طة استخدام طريقة المنحنيات المستعرضة. االسطح التي تم دراستها تم تكوينها ساتتم بو عملي،هذا البحث يقدم استراتيجية لتصميم االسطح بشكل باستخدامتوصيف طريقة تعريف ونمذجة النقاط باستخدام تطبيقات الهندسة العكسية فضال عنسلسلة من الشرائح المتعاقبة المكونة للشكل. طةسابو مجال التطبيق المالئم لها. إليضاح b-spline) لتمثيل الحاالت المختلفة لمنحنيات الـ ureolمن مادة ( تم تنفيذ نموذجين االحداثيات.مكائن قياس لغرض ربط المنحنيات وتكوين السطوح ug-nx9ثم تم نقلها الى برنامج الـ matlabبرنامج الـ طةسابوالبيانات المطلوبة تم تصميمها االخطاء المزامنة رال ظها vericutبرنامج الـ باستخدامكذلك تم عمل محاكاة افتراضية نماذج.بالالخاصة g-codeوالحصول على برامج الـ االحداثيات ماكنة قياس باستخدام). في نهاية هذه االجراءات تم قياس النماذج iselلعملية التشغيل. تم تنفيذ النماذج على ماكنة تفريز لثالثة محاور نوع ( )faro arm cmm(، وجد ان ق) لنموذج المنحنيات المستعرضة 0.0589يمة معدل الخطأ (نوع الـ باستخدامb-spline ،المنتظم )0.1337و ( ها يمكن برمجتها في ؤمنتظم. يمكن االستنتاج ان خطوات البرنامج المقترح التي تم بناالغير b-splineالـ باستخداملنموذج المنحنيات المستعرضة تصميمي.وقت أقصربرنامج تصميمي واحد من هذا يمكننا تنفيذ اي سطح في 126-131 al-khwarizmi engineering journal,vol. 12, no. 4, p.p. synthesis of cuo n nano technology and (received http://dx.doi.org/10.22153/kej.2016.07.001 abstract cuo nanoparticles were synthesized in two different ways monohydrate cu(co2ch13)2·h2o, glacial acetic acid sol-gel method using copper chloride(cucl electron microscopy (sem) showed that precipitation and solgel process, respectively, at which the particle size diffraction (xrd)manifested that the pure synthesized powder xrd results showed the particles size of highe infrared spectroscopy (ft-ir) were used to describe the prepared cuo nanostructures which confirms that the synthesized product is keywords: cuo nanostructure, precipitation 1. introduction nanotechnology is a unique branch of science that deals with materials in a very small size between (1-100 nm) with different crystal shapes such as spherical nanoparticles, flower like, nano rods, nano ribbons, nano platelets. the matchless physical and chemical attributes are result from its high surface-to-volume ratio comparing with micro or bulk-sized [1]. authorship of high durability nanomaterials with keeping to chemical pureness, phase selectivity, crystallinity and analogy in particle size with controlled state of agglomeration in a cost procedure is still a challenge to material chemists [2] various methods have been used to produc cuo. these comprise; rapid precipitation coating, solid state reaction, chemical deposition, sonochemical reaction, sol chemical bath deposition, solvothermal process, electrochemical method, spray pyrolysis, thermal oxidation and hydrothermal route. [3] khwarizmi engineering journal,vol. 12, no. 4, p.p. 126-131 (2016) nano structure via sol-gel and precipitation chemical methods saja mohsen jabbar y and advanced material research center/ university of technology n@yahoo.comsmuhci email: (received 22 march 2016; accepted 11 july 2016) http://dx.doi.org/10.22153/kej.2016.07.001 cuo nanoparticles were synthesized in two different ways, firstly by precipitation method using copper acetate ·h2o, glacial acetic acid (ch3cooh) and sodium hydroxide(naoh), gel method using copper chloride(cucl2), sodium hydroxide (naoh) and ethanol (c2 that different cuo nanostructures (spherical and reef) respectively, at which the particle size was found to be less than 2 µm. x the pure synthesized powder has no inclusions that may exist during preparations. xrd results showed the particles size of highest peak at 38.9°, was equal to (15.93nm). in addition, ir) were used to describe the prepared cuo nanostructures absorption peak at 610 cm firms that the synthesized product is a pure cuo and may be attributed to cu2o infrared active mode. cuo nanostructure, precipitation method, solgel method. nanotechnology is a unique branch of science deals with materials in a very small size different crystal shapes such as spherical nanoparticles, flower like, nano ribbons, nano platelets. the matchless physical and chemical attributes are result from its volume ratio comparing with uthorship of high with keeping to vity, crystallinity ، and analogy in particle size with controlled agglomeration in a cost-effective to material chemists used to produce rapid precipitation, spin coating, solid state reaction, chemical vapor deposition, sonochemical reaction, sol-gel route, chemical bath deposition, solvothermal process, electrochemical method, spray pyrolysis, thermal hydrothermal route. [3] the precipitation and hydrothermal routes are predominating used because they are friendly to the environment , safe and the most attractive and practical route that could be costperformance and simple implementation is the quick precipitation method of all the above composition procedures sol gel process has many beneficial. solitary sol gel installation can yield materials at ultra temperatures, synthesize nearly any substance, co-synthesize two or more substances with each other, exactly observance the microstructure of the end outputs, and punctually dominance the physical ،mechanical, and chemical characterizes of the final since the chemical and physical attribute of cuo just based on its size an numerous researchers have centered their endeavor on the found of nano construction of cuo in order to stratify them in optoelectronics, biosensors nanomaterials have the merit of a low surface potential partition than that of metals, al-khwarizmi engineering journal (2016) precipitation university of technology firstly by precipitation method using copper acetate (ch3cooh) and sodium hydroxide(naoh), and secondly by h6o). results of scanning (spherical and reef) can be formed using to be less than 2 µm. x-ray no inclusions that may exist during preparations. in addition, fourier transform absorption peak at 610 cm-1 o infrared active mode. and hydrothermal routes are predominating used because they are friendly to safe and the most attractive and could be used because of its performance and simple implementation is the quick precipitation method [4]. composition procedures solprocess has many beneficial. solitary solinstallation can yield materials at ultra-low temperatures, synthesize nearly any substance, synthesize two or more substances with each exactly observance the microstructure of outputs, and punctually dominance the mechanical, and chemical outputs [5]. since the chemical and physical attribute of cuo just based on its size and morphology, so numerous researchers have centered their endeavor on the found of nano construction of cuo in order to stratify them in nano electronics, optoelectronics, biosensors etc [3]. cuo have the merit of a low surface than that of metals, which saja mohsen jabbar al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 126131(2016) 127 influence on electron field release possession. cuo consider as a potential field emitter, an strong catalytic factor, as well as a valid gas sensing substance. it likewise shows a significant assignment in optoelectronics and solar cell. the metal elements are capable to compose a large variety of oxide compounds. these can take on a great number of constitutional geometries with an electronic structure that able to display metallic,semiconductor or insulator individuality.[6] oxide nanoparticles can exhibit unique physical and chemical properties due to their limited size and high density of corner or edge surface sites. particle size is expected to influence three important groups of basic properties in any material. the first one comprises the structural characteristics, namely, the lattice symmetry and cell parameters. bulk oxides are usually robust and stable systems with well-defined crystallographic structures. however, the growing importance of surface-free energy and stress with decreasing particle size must be considered: changes in thermodynamic stability associated with size can induce modification of cell parameters and/or structural transformations , and in extreme cases the nanoparticle can disappear due to interactions with its surrounding environment and the high surface-free energy . nanomaterials have become important owing to their small size and large surface area. they exhibit unique properties which are not seen in bulk materials [7] in the present investigation, we have synthesized cuo nanoparticles using low cost solgel process and the most safe and environmentally friendly precipitation method. 2. experimental work 2.1. first route: chemical precipitation in order to prepare the nano copper oxide by precipitation route, it was done in two stages: the first was dissolving 1.5g of copper acetate monohydrate(cu(co2ch3)2 · h2o) in 300 ml of distilled water and then added three drops of glacial acetic acid in a volumetric flask at high mixing speed and 32 0c. the second stage: dissolving 8 g of sodium hydroxide in 200 ml of distilled water was added drop by drop to the prepared solution in the first stage which turns from bright blue to dark blue, and leaved for one day to turn black. centrifuge machine is used to filter the black sludge(15min and 490rpm) and washed with water. the sample allowed to dry at room temperature then annealed at temperature 700°c using carbolite cwf 1200 degc, 1200 laboratory chamber furnace. the annealed sample of copper oxide nanoparticles was grinded. 2.2. second route: solgel method the synthesis of nano copper oxide by sol-gel method was as fellow: 0.9 g of copper (ii) chloride was dissolved in 25 ml of ethanol, 1.5 g of sodium hydroxide was dissolved in 80 ml ethanol. the prepared sodium hydroxide solution was added drop wise to copper chloride solution with constant stirring at room temperature for 30 min .reaction occurs and colour turns from dark blue to black .filter paper is used to filter the gel and washed with water. the sample allowed to dry at room temperature then annealed at temperature 700°c using carbolite cwf 1200 degc, 1200 laboratory chamber furnace. the annealed sample of copper oxide nanoparticles was grinded. for the two routes the crystal structure of the cuo nanostructure has been determined by x-ray diffraction (philips pw 1050 x-ray diffract meter of 1.5οa from cu-kα, fourier transform infrared spectroscopy (shimadzo iraffinity) and the surface morphology of cuo nanostructure were examined by scanning electron microscope (sem-vacan). 3. results and discussion x-ray diffraction analysis 3.1. x-ray crystallography considered a tool used for identifying the atomic and molecular structure of a crystal, in which the crystalline atoms cause a beam of incident x-rays to diffract into many specific directions. the crystal structure of cuo nanoparticles prepared by both methods has been showed in fig. (1) at cukα (λ = 1.54056 a) in the 2θ range from 20° to 80°. the crystallite sizes of the particles were calculated by using scherrer's equation. d = kλ / βcosθ ....(1) where, d is the crystallite size of the particles, k is a shape factor (k=0.9 in this work), λ is the wavelength of the incident1 x-ray (1.54056 a, cukα), θ is the diffraction angle and β is the fullwidth half maximum. saja mohsen jabbar al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 126131(2016) 128 x-ray diffraction (xrd) pattern higher intensity peaks located at 38.9°, 35.6° and 48.9° which corresponds to the atomic planes (111), (111) and (-202) respectively. these diffraction planes were well fit with mohammed et.al [8] who prepare copper(ii)-oxide (cu=o) nanostructures with different sizes and shapes and their applied in different man daily life applications. in this study the particles size of highest peak (38.9°), is (15.93nm). table 1, shows size, diffraction angle, full width at half maximum, d spacing and diffraction plane of cuo sample. table 1, size, diffraction angle, full width at half maximum, d spacing and diffraction plane of cuo sample. fig. 1. xrd pattern of prepared cuo nanoparticles. 3.2. infra-red fourier transformation analysis (ft-ir ) in order to be sure of the chemical and structural nature of the material, ft-ir spectroscopy analysis has been done. cuo nanoparticles prepared in both methods has been scanned from 4000 cm-1 to 400cm-1 as shown in fig. (2). it can be noticed two active peaks in the range of 400 to 600 cm-1 which corresponding to stretching vibrations of cuo bond in the monoclinic cuo[9]. absorption bands in the range (1300 and 2000 cm-1 ) are mainly attributed to the chemisorbed and/or physisorbed h2o and co2 molecules that may attached on the surface of nano-structured cuo crystals[10]. furthermore the absence of absorption peak at 610 cm-1 confirms that the synthesized product is pure cuo and may attributed to cu2o infrared active mode [11] . fig. 2. ft-ir spectrum of prepared cuo nanoparticles. peak no. diffraction angle [degree] fwhm [radians] d spacing [nm] diffraction plane 1 38.96 0.0093 2.3095 100 2 35.68 0.0116 2.5138 67 3 48.92 0.0085 1.8602 26 saja mohsen jabbar al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 126131(2016) 129 3.3. morphology of copper oxide (sem) cuo-nps prepared by both strategies (i.e. precipitation and sol-gel methods) and the size of the produced cuo nanoparticles has been investigated by sem with different magnifications shown in fig. (3 and 4) respectively. it can be noticed that there is difference in cuo structure since it tends to be more spherical with quasi architectural by precipitation method with homogeneous distribution and small agglomeration. in the present work copper acetate monohydrate (cu(co2ch3)2.h2o) has been used to prepare cuo nano particles with spherical shape via prescepitation method, the same morphology has been obtained using cu (no3)2. 3h2o as reported by anandan et al. who reported synthesis cuo crystallites self-organized into spherical assemblies or ‘‘dandelions’’ with a puffy appearance [12] and kannaki et.al.[13] who used cuso4 .5h2o shows that how the cuo nanocrystals organized into spherical assemblies. with higher magnification on individual particle it appears like dandelion. moreover copper (ii) chloride that used to prepare cuo structure via sol gel is more like reef with more ability to be agglomerate. fig. 3. sem photographs of cuo nanoparticles prepared via precipitation method. fig. 4. sem photographs of cuo nanoparticles prepared via solgel method. 4. conclusion copper oxide can be synthesized using precipitation and solgel methods that were very efficient in producing small sized nanostructures(less than 2 µm). in this study, it has been noticed that the emergence of small nanoscale structures in various forms depending on the type of preparing and this makes it suitable for different applications. it wasobserved that shape, size, and homogeneity of the assynthesized products depend uponvarious reactions conditions, i.e., the nature of the ligand, the relative concentration ofreagents, the solvent, the overall concentration of reagents, the reaction time, the evapo-ration time, and the reaction/evaporation temperature . 5. references [1] pallavi b. nalle; asha navpute; s. p. jadhav ، b. r. shinde; s. u. shinde;k. m. jadhav, (2013), " synthesis, structural and ultrasonic saja mohsen jabbar al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 126131(2016) 130 characterization of cuo nanofluid", international journal of science and research (ijsr), issn (online): 2319-7064. [2] acharyulu n. ; dubey r. ; swaminadham v.; pratap k.; kalyani r. ; and pammi s., (2014)," green synthesis of cuo nanoparticles using phyllanthus amarus leaf extract and their antibacterial activity against multidrug resistance bacteria", international journal of engineering research & technology (ijert) issn: 2278-0181, vol. 3 issue4. [3] sylvester l.;valentine b.; joseph e.; fidelix e.; sabastine c.;fabian i., (2013), " annealing effect on the optical and solid state properties of cupric oxide thin films deposited using the aqueous chemical growth (acg) method", vol.5, no.3, 389399. [4] mahdi s.; nor a.; norhazlin z.; nilofar a.; bakhtyar b.; zaharim a.; sopian k.,(2013),"effect of ph on the synthesis of cuo nanosheets by quick precipitation method", issue 2, volume 9. [5] asha a.; baskaran b., (2014), " structural and optical absorption analysis of cuo nanoparticles", indian journal of advances in chemical science 2 (2) 158-161. [6] sanjay s.; mahendra k.;arvind a.; and sudhanshu k., (2013)," synthesis and characterisation of copper oxide nanoparticles", iosr journal of applied physics (iosr-jap), volume 5, issue 4, pp 61-65. [7] nittaya t.; chaikarn l. and sukon p.," synthesis of thermally spherical cuo nanoparticles",(2014), journal of nanomaterials, volume 2014. [8] mohammed s.; muath m.; amjad h.;belkheir h.; taibi b.; ismail w.,(2013),"copper (ii)-oxide nanostructures: synthesis, characterizations and their applications–review", j. mater. environ. sci. 4 (5) ,792-797. [9] erdogan i.; gullu o.; alloy. j.,(2010), compd. 492 , 378383. [10] ranjbar-karimi r.; bazmandegan-shamili a.; aslani a.; kaviani k., (2010), physica b 405, 30963100. [11] karthik k.; victor jaya n.; kanagaraj m.; arumugam s.,(2011), solid state commun 151, 564-568. [12] sambandam a.; shine y.,(2007), "emergent methods to synthesize and characterize semiconductor cuo nano particles with various morphologies – an overview", journal of experimental nanoscience, vol. 2, nos. 1-2, p.23-56. [13] kannaki k.; ramesh p.; and geetha d.,(2012), "hydrothermal synthesis of cuo nanostructure and their characterizations", international journal of scientific & engineering research volume 3, issue 9. ��� ���ر�� ��� 4، ا���د�12� � ا���ارز � ا������� ا���� ،131-126 )2016( 131 �وا�'#��" –ا���,�(� +*#()'� ا���ل $�%�# $#ا �" او ��� ا����س ��� ���ر .م�� � وا���اد ا����������� !"��ث ا� $#&' ()*�/ �+���� ا�-$�,� ا��! � smuhcin@yahoo.com:ا�0*/� ا.�!�*و# �� ا��/ ا��*�8�c$' ;+cام a@ت ا� &$س ا��$<+� "= "&>+* ا��*ا(+; ا� $#�/� .و(:+� ا� &$س '4*/��+5 ��67�8+5، ا�4*/�� ا.و�3 ھ� ط*/�� co2ch13)2.h2o( d+78ا� e�$f7-ا�، وg �)ch3cooh ( م��د/hوھ+�رو(:+� ا�naohل�$�8�cام (7�ر/� ' �k، وا�4*/�� ا�g$#+� ھ� ط*/�� ا�: �د/�م ) cucl2(ا� &$س hھ+�رو(:+� ا� ،naoh ل�#$g/.وا)c2h6o(. ت*lأظ *l-ا�� o>$�# �"*ا(+; #$#�/� 'rs!$ل )sem( ا��$qc ا�p!�*و# �67�8�)k!t$#+� ا��ى �**aل) (*و/� وا�4*/��� ا��*c+; وا�:' v#�!" 5� kwن ا$) �#� وأظl*ت .�$/!*ون ٢�37z k ا���ا�� وf-= ا�-)/y$ت ا���! o>$�# د�+f ز$l� �,r]ا�:+ +� ا)(xrd م�z د��ا<; و�r ��دة "!�ن �w ا���� ھ� ،)در�� 37z. ��w )٣٨.٩ ا�-y/($ت ا��&>+* وf-= أ` $ء � )١٥.٩٣*���7� .) )ftirم �g$+4+� ا.r,� ا��&v ا�&�*اء اا�8�c"= و (#$#aا��*(+; ا��ا �g*,�� ��w $l"*lاظ �+�$z ي ا��&>* ' �$وة�و(:+� ا� &$س ا� $# � z ص$h��.٦١٠ا =c-١. 89-106 al-khwarizmi engineering journal,vol. 11, no. prediction of performance equations for household compressors depending on manufacturing data for refrigerators louay abd alazez mahdi *,**,***department (received abstract a surface fitting model is developed based on calorimeter data for two famous brands of household compressors. correlation equations of ten coefficient polynomials were found as a temperatures in range of (-35℃ to -10 refrigerant mass flow rate. additional correlations equations for these variables as a quick choic ashrae standard that cover a range of swept volume range (2.24 the result indicated that these surface fitting models are accurate with in ± 15% for 72 compressors model of cooling capacity and 50 models for power consumption and 25 models for refrigerant mass flow rate. keywords: performance, compressors, 1. introduction the household compressors manufactured in the world due to the wide range of usage in refrigerators and freezers. a lot of brands and models are available which may cause troubles in selecting the proper compressor and type. the refrigerators and freezers may have no identifying data when the maintenance engineers work to replace the compressors. also, engineers who asked about general model can be used to select the household compressors . all these reasons stand behind the present research to find general correlations f capacity, power consumption, and mass flow rate that cover the compressors performance and application. khwarizmi engineering journal,vol. 11, no. 4, p.p. 89-106 (2015) prediction of performance equations for household compressors depending on manufacturing data for refrigerators and freezers alazez mahdi* emad esmaael habib laith abd almunam*** *,**,***department of mechanical engineering/ university of technology email: louayalkaesy@gmail.com email: emad_1955_emad@yahoo.com email: laith.ismael@ymail.com (received 20 november 2015 ; accepted 16 june 2015) a surface fitting model is developed based on calorimeter data for two famous brands of household compressors. correlation equations of ten coefficient polynomials were found as a function of refrigerant saturating and evaporating 10℃) using matlab software for cooling capacity, power consumption, and additional correlations equations for these variables as a quick choice selection for a proper compressor use that cover a range of swept volume range (2.24-11.15) cm3. the result indicated that these surface fitting models are accurate with in ± 15% for 72 compressors model of models for power consumption and 25 models for refrigerant mass flow rate. manufacturing, data, equations. the household compressors are widely manufactured in the world due to the wide range of usage in refrigerators and freezers. a lot of brands and models are available which may cause troubles in selecting the proper compressor and type. the refrigerators and freezers may have no ntifying data when the maintenance engineers work to replace the compressors. also, engineers who asked about general model can be used to all these reasons stand behind the present research to find general correlations for cooling capacity, power consumption, and mass flow rate that cover the compressors performance and 2. literature review it is found in literatures that few researchers pay attention to the subject of general performance equation among them duggan.et.al. [1] compared between two experimental methods of compressor test, calorimeter and flow rater test in order to know the more efficient method. the researcher recommended that the flow rater test is more accurate than calorimeter. cavallini.et.al. [2] in their work presented a procedure for a steady state thermal analysis of a hermetic reciprocating compressor. the compressor machine was subdivided into six parts. the energy balance was established for each part and overall system to obtai distribution inside the compressor machine and the heat flow rates exchanged. the results were compared against the experimental measurements carried out on commercial units operating with r al-khwarizmi engineering journal (2015) prediction of performance equations for household compressors depending on manufacturing data for refrigerators emad esmaael habib** university of technology a surface fitting model is developed based on calorimeter data for two famous brands of household compressors. function of refrigerant saturating and evaporating ) using matlab software for cooling capacity, power consumption, and e selection for a proper compressor use at the result indicated that these surface fitting models are accurate with in ± 15% for 72 compressors model of models for power consumption and 25 models for refrigerant mass flow rate. it is found in literatures that few researchers pay attention to the subject of general performance equation among ] compared between two experimental methods of compressor test, calorimeter and flow rater test in order to know the more efficient method. the researcher recommended that the flow rater test is more ] in their work presented a procedure for a steady state thermal analysis of a hermetic reciprocating compressor. the compressor machine was subdivided into six parts. the energy balance was established for each part and overall system to obtain the temperature distribution inside the compressor machine and the heat flow rates exchanged. the results were compared against the experimental measurements carried out on commercial units operating with rlouay abd alazez mahdi al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 89106 (2015) 90 600a and r-134a, and a good agreement was found. mackensen.et.al. [3] identified a physics based method to characterize the compressor performance in refrigeration systems with limited experimental data. the work focused on positive displacement compressors, semi-hermetic and open type. the compressors data were obtained from various manufacturers. the refrigerant mass flow rates were based on the polytropic compression process with clearance volume that leads to a volumetric efficiency expression. the overall performance of the model was acceptable with maximum average mean errors of 3.7% for reciprocating compressor, 2.3% for scroll compressor, and 0.6% for screw compressor. kim and bullard.[4] developed a simple physical model for small hermetic reciprocating, rotary and scroll compressors based on thermodynamic principles and large data sets from the compressor calorimeter and in situ tests. pressure losses along the refrigerant path were neglected, and the compression process was isentropic. a mass flow rate model reflected the clearance volume efficiency and simulated the suction of gas heating using an effectiveness method. compressor work was calculated using the compressor efficiency represented by two empirical parameters. a linear relationship between the discharge and shell temperatures was extracted from large data sets and applied to the model for calculating the discharge temperature. the model that found can predict the mass flow rate and power consumption within ∓3.0% accuracy. jähnig.et.al. [5] investigated a semiempirical model to represent the compressor performance. the model was based on the volumetric efficiency and assumed a polytropic compression process. the single point condition currently used for rating refrigerator/freezer compressors is an evaporating temperature of – 23.3°c (–10°f) and a condensing temperature of 54.4°c (130°f) in a 32.2°c (90°f) environment. the model was not extrapolated from static (zero air velocity) cooling to forced cooling or viceversa. cezar.et.al. [6] proposed a semi-empirical mathematical model to simulate the unsteady behavior of mass flow rate and power of reciprocating compressors. the model based on thermodynamic equations is linearly fitted to calorimeter data sets of two compressors. comparisons of computed and measured values of mass flow rate and power, in transient regime, were conducted for two fitted compressor curves. a good agreement of results was found for both compressors in start-up tests. they concluded that the proposed semi-empirical model can safely applied to dynamic simulations of the whole refrigeration system. the work proposed a semiempirical model to predict the performance of reciprocating compressor in transient regime. the model based on thermodynamic equations fitted to manufacturer data by using linear correlations and compared with experimental data are which quite accurate with the prediction of compressor mass flow rate and power. the previous literatures do not explore the performance of a wide range of compressors and help the designer and the engineers to select the proper compressor size from the wide production brands. therefore, the aim of this work is to find theoretical general equations for cooling capacity, power consumption, and refrigerant mass flow rate for ranges of compressors swept volume (2.42-11.15) cm3 depending on calorimeter data, these equations are easy to use and find the requirement of the compressors without depending on the brand. 3. data collection the compressors brands are: danfoss, electrolux, tecumseh, tee, embraco, acc, kulthorn kirby, and donper. twenty-five sets of calorimeter test data for hermetic reciprocating compressors have been studied for danfoss and electrolux compressors which cover the swept volume from (2.42-11.15) cm3 working with refrigerant 134a. the cooling capacity calorimeter set data that available are ninety sets and fifty-nine for power and thirty-four for refrigerant mass flow rate. these sets were used to compare and find the deviation from the correlations that obtained. the compressor brands and models and the available data set for cooling capacity, power, and refrigerant mass flow rate which depend on the following common points for the compressors used in thesis research are presented in table (4): 1. hermetic reciprocating 2. low back pressure 3. static cooling method 4. rsir motor type (resistance start— induction run) 5. r-134a is working fluid 6. ester oil type 7. 220v, 1ph, 50hz power. louay abd alazez mahdi al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 89106 (2015) 91 4. approximation functions the goal of the approximation functions, is to obtain the best dependable fitting curves to measure the dependability of the fitted curves corresponding values r2 were calculated, where r2 is given by [7]: �� = ∑�� − ���� ∑�� − ���� y is the measured data yn is the estimated(calculated) value and y ̅ is the mean of y. depending on electrolux and danfoss compressor brand using the available data for capacity, power, and refrigerant mass flow rate for 25 size that cover 2.42 11.15 cm3 swept volume represented are in table (4). a surface fitting method was used with matlab software to find the following correlations: 4.1. cooling capacity the cooling capacity correlation was found based on ari 540-90 standard [8]. the results are plotted in figure (1); the correlation was as follow: �� = �� + �� ∗ � + �� ∗ �� + �� ∗ �� + �� ∗ � ∗ �� + �� ∗ �� � + �� ∗ �� + �� ∗ �� ∗ �� + �� ∗ � ∗ �� � + �� ∗ �� � …(1) table 1, coefficients of cooling capacity correlation. coefficient value range a0 -18.24 -53.16, 16.67 a1 78.54 68.45, 88.64 a2 0.7153 -3.1, 4.531 a3 0.2132 -1.123, 1.549 a4 2.877 2.505, 3.248 a5 0.04653 -0.118, 0.2111 a6 -0.04921 -0.1119, 0.01344 a7 -0.01148 -0.03118, 0.008213 a8 0.02749 0.02149, 0.03349 a9 0.0006736 -0.00169, 0.003037 goodness of fit: r2: 0.9968 where s: swept volume cm3 te: evaporator temperature. the value of r2 is 0.9968 which indicates the degree of correlation i.e. (99.68%) of total variation present. 4.2. power consumption it depends on ari 540-90 standard, the corresponding data is plotted in figure (2) and the following correlation was found: � = �� + �� ∗ � + �� ∗ �� + �� ∗ �� + �� ∗ � ∗ �� + �� ∗ �� � + �� ∗ �� + �� ∗ �� ∗ �� + �� ∗ � ∗ �� � + �� ∗ �� � …(2) table 2, coefficients of power consumption correlation. the value of r2 is 0.9945 which indicates the degree of correlation, i.e., (99.45%) of total variation included. 4.3. refrigeration mass flow rate the results of the fitting are shown in figure [3] and given by; ! " = #� + #� ∗ � + #� ∗ �� + #� ∗ �� + #� ∗ � ∗ �� + #� ∗ �� � + #� ∗ �� + #� ∗ �� ∗ �� + #� ∗ � ∗ �� � + #� ∗ �� � …(3) table 3, coefficients of refrigerant mass flow rate correlation. coefficient value range c0 -0.4668 -1.29 ,0.3564 c1 1.55 1.312,1.788 c2 0.0006981 -0.08926,0.09066 c3 0.007452 -0.02405,0.03896 c4 0.05961 0.05085,0.06838 c5 0.0005814 -0.003298,0.004461 c6 -0.0009898 -0.002467,0.0004873 c7 -0.000175 -0.0006394,0.0002894 c8 0.0006249 0.0004834,0.0007663 c9 1.29e-005 -4.282e-005,6.863e-005 goodness of fit: r2: 0.9955 where the value of r2 is 0.9955 which indicates high dependability of fitted. coefficient value range b0 42.46 17.59, 67.33 b1 28.26 21.07, 35.45 b2 -0.1031 -2.821, 2.615 b3 1.266 0.3142, 2.218 b4 0.9115 0.6466, 1.176 b5 -0.01531 -0.1325, 0.1019 b6 -0.06662 -0.1112, -0.022 b7 -0.00426 -0.01829, 0.009771 b8 0.003956 -0.0003186, 0.00823 b9 -0.0004349 -0.002119, 0.001249 goodness of fit: r2: 0.9945 louay abd alazez mahdi al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 89106 (2015) 92 table (5) indicates the minimum and the maximum deviation for each compressor from the results of equations 1, 2, 3 and the indications are: -for cooling capacity qe: it was found that 89 compressors have 30% deviation and 72 compressors have 15% deviation.the deviated compressor brands are donper, tee, k.k. -for power consumption: the deviated compressors were found 59 within 30% deviation and 50 compressors within 15% deviation. the compressor brands that are deviated are donper, k.k. -for refrigerant mass flow rate: 29 compressors were found to be deviated with 30% and 25 compressors were found to be deviated ±15%. the compressor brand that deviated is for tecumsh, this brand is very dependable brand in the world and capacity, and the power data are within the 15% deviation. due to the high demand on the type of compressor that works at (54.4) ℃ condenser temperature and (-23.3) ℃ evaporator temperature for swept volume range [2.42-11.15] cm3, the data of cooling capacity, power consumption, and refrigerant mass flow rate which are working according to ashrae standard 23-1993[9] are correlated where the refrigerant temperatures in the cycle as follows: temperature location ℃ condenser 54.4 evaporator -23.3 sub cooled 32 suction 32 ambient 32 the first number printed in the label plate of the compressors or refrigerators and freezers represents the power consumption (p). this number is used to calculate the swept volume via the following correlation to find the swept volume; � = −3.46234361297 + �1.02257271308e − 001 ∗ �� + �−3.29252164432e − 004 ∗ ��� + �7.45584362830e − 007 ∗ ��� …(4) standard error is 0.0034096 with r2= 0.9999991 ، after that, the cooling capacity and the refrigerant mass flow rate can be found as follow according to the swept volume found: q1 = �−1.84013586272e + 001� + �2.65613665790e + 001 ∗ �� + �4.59664932840e − 001 ∗ ��� + �−4.81895917828e − 002 ∗ ��� …(5) standard error is 0.0249453 and r2: 0.9999999. ! " = �−2.91401871854e − 001� + �4.95966412918e − 001 ∗ �� + �1.23494398093e − 002 ∗ ��� + �−1.03344762424e − 003 ∗ ��� …(6) standard error: 0.0030522 with r2=0.9999974 table (5) is included the deviation results for 76 compressors type according to swept volume. the table represents the cooling capacity, power consumption, and refrigerant mass flow rate for each one according to equations 1, 2, and 3 . these correlations are very helpful for engineers and the designers in order to find the closed compressor type needed for replacement or for new refrigerators or freezers. figures 4, 5,and 6 show the results obtained by correlations 1, 2, 3 for each swept volume at -35 ℃ to -10℃ evaporator temperature and 54.4℃ fixed condensing temperature for cooling capacity, power consumption, and refrigerant mass flow rate. these figures are helpful to find the performance data of all compressors for a wide range of evaporator temperatures. figures 7, 8, and 9 depict the deviation of the correlated and standard data for cooling capacity, power consumption, and refrigerant mass flow rate, respectively. it can be seen that the deviation does not exceed the value of ∓15% for the three parameters, which is acceptable accuracy in practical engineering problems . figures (10-a to10-w), (11-a to 11-s), and (12a to 12-w) represent the deviation between the calorimeter data and correlated data of cooling capacity, power consumption, and refrigerant mass flow rate for swept volume range (2.42 to 11.15) cm3 corresponding to various types compressors, as indicated at each figure. these detailed comparisons show a fairly good agreement with acceptable accuracy for services, maintenance and retrofit proposes. louay abd alazez mahdi al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 89106 (2015) 93 table 4, the available data of compressors brands. item swept volum compressor brand and legend data available cm3 qe p mr 1 2.24 cubigel (gd24aa) y y y 2 2.5 danfoss (pl50f) y y y 2.5 china(d25cz) y y y 3 2.61 danfoss (tl2.5f) y y y 4 2.7 tecumseh(1324y) y n n 5 2.8 tee (az47yp) y n n 6 3 embraco (emt22hlp) y n n 3 donper china (d30cz) y n n 7 3.05 cubigel(gd30aa) y y y 8 3.13 danfoss (tl3f) y y y 9 3.36 acc (of605) y y n 10 3.38 cubigel(gl35aa) y y y 11 3.58 cubigel (gd36aa) y y y 3.58 tecumseh(thb1335y) y y y 12 3.59 tee (az68yd) y n n 13 3.6 donper china (s36cs) y n n 14 3.66 acc (gqy35aa) y y n 15 3.86 danfoss (tl4f) y y y 16 3.9 kulthorn kirby(ae1327y) y y n 17 3.97 embraco (emt36hlp) y n n 18 4 tee (az82 yp) y n n 19 4.01 cubigel (gl40aa) y y y 4.01 acc (gqy40aa) y y n 20 4.03 cubigel (gd40aa) y y y 21 4.07 acc (gvm40aa) y y n 22 4.08 kulthorn kirby(ae1330y) y y n 23 4.23 tecumseh(thb 1340y) y y y 24 4.3 china(s43bz) y n n 25 4.38 acc(of789.02) y y n 26 4.56 cubigel (gl45aa) y y y 27 4.6 kulthorn kirby(ae1335y) y y n 28 4.85 embraco (emt43hlp) y n n 29 5.0 tee(az90 yp) y n n 5.0 donper china(s50cza) y n n 30 5.08 danfoss (tls5f) y y y 31 5.11 kulthorn kirby(ae1340y) y y n 32 5.12 cubigel (gl50aa) y y y 33 5.2 tecumseh(thb1350y) y y y 34 5.3 china(s53bz) y n n 35 5.46 acc(gl50aa.02) y y n 36 5.5 donper china(ek1112cza) y n n 37 5.56 embraco (emt49hlp) y n n 38 5.58 tecumseh(thb1350ys) y y y 39 5.7 danfoss (tls6f) y y y 5.7 acc (gvm57aa) y y n 40 5.75 tee(ae148 yp) y n n 41 5.8 donper china(l58cz) y n n 42 5.99 cubigel (gl60aa) y y y 5.99 kulthorn kirby(ae1350y) y y n 5.99 acc(gqy60aa) y y n 43 6.1 tecumseh(thb 1360 y) y y y 44 6.13 danfoss (nl6f) y y y 45 6.2 embraco(nbt1114z) y n n 46 6.3 donper china(ek1114cza) y n n 47 6.49 danfoss (tls7f) y y y 48 6.5 donper china(l58cz) y n n 49 6.6 acc(gvm66aa) y y n 50 6.64 cubigel (gl70aa) y y y 6.64 acc(l70an.02) y y n 51 6.76 embraco (emt60hlp) y n n 52 6.9 donper china(ek1116cza) y n n 53 6.91 kulthorn kirby (ae1360y) y y n 6.91 tee (ae148 yp) y n n 54 6.93 danfoss(fr7.5f) y y y 55 7.0 acc(gvy66aa.01) y y n 56 7.2 donper china(ek1118cza) y n n 7.2 donper china(l72cz) y n n 57 7.27 danfoss (nl7f) y y y 58 7.39 cubigel (gl75aa) y y y 7.39 acc (gl80aa.02) y y n 59 7.4 embraco (nbt1116z) y n n 60 7.52 acc (gvy75aa) y y n 61 7.94 tee (ae176 yp) y n n 62 7.95 danfoss (nl8f) y y n 63 8.07 embraco(nb1118z) y n n 64 8.09 acc (gl80an) y y n 65 8.1 cubigel (gl80aa) y y y 8.1 embraco (nb1116z) y n n 66 8.12 kulthorn kirby (ae1370y) y y n 67 8.35 danfoss (nl9f) y y y 68 8.8 tecumseh (aez 1365y) y y n 69 8.99 tee (ae196yp) y n n 70 9.05 danfoss (fr10f) y y y 9.05 acc (gqy90aa) y y n 71 9.08 cubigel (gl90aa) y y y 72 9.27 embraco (ne1121z) y n n 73 9.407 tecumseh (aea 1410 yxc) y y y 74 9.42 kulthorn kirby(ae2390y) y y n 75 9.93 cubigel (gl99aa) y y y 76 11.15 danfoss (nl11f) y y y number of compressors to find the general equations(yellow) 25 total number of compressors with swept volume 90 total number of cooling capacity data compressors 90 total number of power data compressors 59 total number of refrigerant mass flow rate data compressors 34 y: available data n: not available louay abd alazez mahdi al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 89106 (2015) 94 table 5, the deviations from the surface fitting model. item swept volum compressor brand and legend deviations qe % p % mr % cm3 min max min max min max 1 2.24 cubigel (gd24aa) 0 2.3 1.1 7.5 0 13 2 2.5 danfoss (pl50f) -10 -4.5 13 15 -8 5 2.5 china(d25cz) -9 -1 18 23 4 14 3 2.61 danfoss (tl2.5f) 9 15 12 14 9 15 4 2.7 tecumseh(1324y) 2 36 x x x x 5 2.8 tee (az47yp) 3 22 x x x x 6 3 embraco (emt22hlp) -17 -12 x x x x 3 donper china (d30cz) -6 11 x x x x 7 3.05 cubigel(gd30aa) -6 2 -4 -1 -3 3 8 3.13 danfoss (tl3f) 7 14 14 15 8 15 9 3.36 acc (of605) -10 2 5 14 x x 10 3.38 cubigel(gl35aa) -6 4 -4 0 -4 4 11 3.58 cubigel (gd36aa) 1 6 -2 2 0 10 3.58 tecumseh(thb1335y) -12 -3 4 7 30 33 12 3.59 tee (az68yd) 9 16 x x x x 13 3.6 donper china (s36cs) -10 -4 x x x x 14 3.66 acc (gqy35aa) -12 -7 13 18 x x 15 3.86 danfoss (tl4f) 0 7 8 11 0 8 16 3.9 kulthorn 3 25 17 21 x x 17 3.97 embraco (emt36hlp) -23 -12 x x x x 18 4 tee (az82 yp) 6 12 x x x x 19 4.01 cubigel (gl40aa) 0 10 4 9 0 15 4.01 acc (gqy40aa) -11 -8 13 17 x x 20 4.03 cubigel (gd40aa) -1 2 -7 -3 2 7 21 4.07 acc (gvm40aa) -24 -10 4 6 x x 22 4.08 kulthorn 6 17 20 26 x x 23 4.23 tecumseh(thb 1340y) -7 0 7.13 7.36 30 35 24 4.3 china(s43bz) -5 7 x x x x 25 4.38 acc(of789.02) -13 -11 -5 0 x x 26 4.56 cubigel (gl45aa) 0 8 3 5 0 6 27 4.6 kulthorn -3 15 8 11.5 x x 28 4.85 embraco (emt43hlp) -19 -10 x x x x 29 5.0 tee(az90 yp) 24 25 x x x x 5.0 donper china(s50cza) -5 7 x x x x 30 5.08 danfoss (tls5f) -11 -8 -3.5 3.5 -4 0 31 5.11 kulthorn -15 16 3 9 x x 32 5.12 cubigel (gl50aa) -2 4 0 3 0 6 33 5.2 tecumseh(thb1350y) 2 6 4 6 35 38 34 5.3 china(s53bz) -10 10 x x x x 35 5.46 acc(gl50aa.02) 2 4 3 5 x x 36 5.5 donper china(ek1112cza) -8 -6 x x x x 37 5.56 embraco (emt49hlp) -7 -15 x x x x 38 5.58 tecumseh(thb1350ys) 9 14 10 10.5 40 43 39 5.7 danfoss (tls6f) -6 -2 0 3 -7 0 5.7 acc (gvm57aa) -14 -8 -4 2 x x 40 5.75 tee(ae148 yp) 11 12 x x x x 41 5.8 donper china(l58cz) -19 -5 x x x x 42 5.99 cubigel (gl60aa) 0 5 -3 0 0 6 5.99 kulthorn -5 9 -5 5 x x 5.99 acc(gqy60aa) -10 -6 8 11 x x 43 6.1 tecumseh(thb 1360 y) -2 4 -2 7 34 39 44 6.13 danfoss (nl6f) -5 5 5 9 -5 6 45 6.2 embraco(nbt1114z) -6 -4 x x x x 46 6.3 donper -10 -8 x x x x 47 6.49 danfoss (tls7f) -5 -1 -2 0 -5 0 48 6.5 donper china(l58cz) 0 6 x x x x 49 6.6 acc(gvm66aa) -11 -7 -4 -1 x x louay abd alazez mahdi al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 89106 (2015) 95 50 6.64 cubigel (gl70aa) 0 5 -3 0 0 9.5 6.64 acc(l70an.02) -8 -4 -12 -3 x x 51 6.76 embraco (emt60hlp) -9 -3 x x x x 52 6.9 donper -12 -3 x x x x 53 6.91 kulthorn kirby -3 9 2 6 x x 6.91 tee (ae148 yp) 12 14 x x x x 54 6.93 danfoss(fr7.5f) 5 14 8 11 8 20 55 7.0 acc(gvy66aa.01) -8 -4 4 9 x x 56 7.2 donper -28 6 x x x x 7.2 donper china(l72cz) -6 9 x x x x 57 7.27 danfoss (nl7f) -6 -3 -2 6 -4 2 58 7.39 cubigel (gl75aa) 0 3 0 4 2 8 7.39 acc (gl80aa.02) -8 -5 0 2 x x 59 7.4 embraco (nbt1116z) -5.3 -4.3 x x x x 60 7.52 acc (gvy75aa) -9 -7 3 7 x x 61 7.94 tee (ae176 yp) 10 12 x x x x 62 7.95 danfoss (nl8f) -7 -4 -4 6 x x 63 8.07 embraco(nb1118z) -1.5 1.5 x x x x 64 8.09 acc (gl80an) -2 5 -8 -2 x x 65 8.1 cubigel (gl80aa) 0 9 -3 3 0 10 8.1 embraco (nb1116z) -6 10 x x x x 66 8.12 kulthorn kirby -16 16 -6 13 x x 67 8.35 danfoss (nl9f) -3 3 0 5 -2 3 68 8.8 tecumseh (aez 1365y) 10 26 0 8 x x 69 8.99 tee (ae196yp) 10 12.5 x x x x 70 9.05 danfoss (fr10f) 2 16 6 9 10 12.5 9.05 acc (gqy90aa) -15 -6 0 7 x x 71 9.08 cubigel (gl90aa) 0 3 -6 -3 3 6 72 9.27 embraco (ne1121z) -10 -8 x x x x 73 9.407 tecumseh (aea 1410 -8 0 -30 -12 -3 12 74 9.42 kulthorn 2 20 -3 12 x x 75 9.93 cubigel (gl99aa) 2 9 1 2.5 -5 7 76 11.15 danfoss (nl11f) -4 -1 -2 4 -4 2 total number of compressors with 15% cooling capacity deviation 72 18 total number of compressors with 15% power deviation 50 9 total number of compressors with 15% refrigerant mass flow rate deviation 25 9 compressors brand: electrolux cubigel, danfoss, tecumseh, tee, embraco, acc, kulthorn kirby(turky) , donper(china) 8 fig. 1. show the surface fitting for compressors cooling capacity via te & swept volume. swept volume t evaporator o cooling capacity w louay abd alazez mahdi al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 89106 (2015) 96 fig. 2. show the surface fitting for compressors power via te & swept volume. fig. 3. show the surface fitting for compressors refrigerant mass flow rate via te & swept volume. fig. 4. the cooling capacity curves for the compressors via the evaporator temperatures for range of swept volume [s=2.42 to 11.15] cm3. fig. 5. power consumption curves for the compressors via the evaporator temperatures for range of swept volume [s=2.42 to 11.15] cm3. -40 -35 -30 -25 -20 -15 -10 -5 0 50 100 150 200 250 300 350 400 450 500 550 te [°c] c oo lin g c ap ac iti es [ w ] s=2.42 s=3.05 s=3.58 s=4.01 s=4.56 s=5.08 s=5.99 s=6.49 s=7.39 s=8.1 s=8.35 s=9.05 s=9.93 s=11.15 -23.3 °c -40 -35 -30 -25 -20 -15 -10 -5 0 50 100 150 200 250 300 350 te [°c] p ow er [ w ] s=2.42 s=3.05 s=3.58 s=4.01 s=4.56 s=5.08 s=5.99 s=6.49 s=7.39 s=8.1 s=8.35 s=9.05 s=9.93 s=11.15 -23.3 °c swept volume 3 power w t evaporator refrigerant mass flow rate kg/hr t evaporator oc swept volume louay abd alazez mahdi al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 89106 (2015) 97 0 50 100 150 200 250 0 50 100 150 200 250 0 2 4 6 8 10 12 correleted power data [w] a ct ua l p ow er [ w ] s w ep t v ol um e [c m 3 ] +15% -15% 0 1 2 3 4 5 6 0 1 2 3 4 5 6 0 2 4 6 8 10 12 correleted refrigerant mass flow [kg/hr] a ct ua l r ef rig er an t m as s flo w [ kg /h r] s w ep t v ol um e [c m 3 ] +15% -15% fig. 6. refrigerant mass flow rate curves for the compressors via the evaporator temperatures for range of swept volume [s=2.42-11.15] cc. fig. 7. the deviation for the cooling capacity between correlated results and available data. fig. 8. the deviation for the power consumption between correlated results and available data. fig. 9. the deviation for the refrigerant mass flow rate between correlated results and available data. -40 -35 -30 -25 -20 -15 -10 -5 0 1 2 3 4 5 6 7 8 9 10 11 te [°c] r ef rig er an t m as s flo w ra te [k g/ hr ] s=2.42 s=3.05 s=3.58 s=4.01 s=4.56 s=5.08 s=5.99 s=6.49 s=7.39 s=8.1 s=8.35 s=9.05 s=9.93 s=11.15 -23.3 °c 0 50 100 150 200 250 300 0 50 100 150 200 250 300 0 2 4 6 8 10 12 co rreleted cool ing capaci ty [w] a ct ua l c oo lin g ca pa ci ty [ w ] s w ep t v ol um e [c m 3 ] +15% -15% louay abd alazez mahdi al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 89106 (2015) 98 -40 -35 -30 -25 -20 -15 -10 -5 0 25 50 75 100 125 te [°c] c oo lin g ca pa ci ty [w ] data f orm matlab eq.[s=2.42] electrolex g d24aa[s=2.42] -40 -35 -30 -25 -20 -15 -10 -5 0 25 50 75 100 125 150 175 te [°c] c oo lin g c ap ac ity [ w ] embraco emt22hlp[s=3.0] electrolex g d30aa[s=3.05] donper d30cz[s=3.0] data f rom matlab eq.[s=3.05] -40 -35 -30 -25 -20 -15 -10 -5 0 20 40 60 80 100 120 140 160 180 200 te [°c] c oo lin g ca pa ci ty [w ] electrolex g d36aa[s=3.58] tee az68yd[s=3.59] acc g q y35aa[s=3.66] donper s36c6[s=3.6] tecumseh thb 1335y[s=3.358] data f rom matlab eq.[s=3.58] -40 -35 -30 -25 -20 -15 -10 -5 0 25 50 75 100 125 150 175 200 225 te [°c] c oo lin g c ap a ci ty [ w ] embraco emt36hlp[s=3.97] tee az82yp[s=4.0] electrolex g l40aa[s=4.01] acc g q y40aa[s=4.01] kulthorn kirby ae1330y[s=3.9] data f rom matlab eq.[s=4.01] -40 -35 -30 -25 -20 -15 -10 -5 0 25 50 75 100 125 150 175 200 225 250 te [°c] c oo lin g c ap ac ity [ w ] data f rom matlab eq.[s=4.56] electrolex g d45aa [s=4.56] k k ae1335y[s=4.6] -40 -35 -30 -25 -20 -15 -10 -5 0 50 100 150 200 250 300 te [°c] c oo lin g c a pa ci ty [ w ] data f rom matlab[5.12] k k ae1340y[s=5.11] electrolex g d50aa[s=5.12] tecumseh thb 1350y[s=5.2] [10-a] [10-c] [10-e] [10-b] [10-d] [10-f] louay abd alazez mahdi al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 89106 (2015) 99 -40 -35 -30 -25 -20 -15 -10 -5 0 50 100 150 200 250 300 350 te [°c] c oo lin g c ap ac ity [w ] danf oss tls6f[s=5.7] acc g vm57aa[s=5.7] tee ae148yp[s=5.75] donper l58cz[s=5.8] donper lu58cz[s=5.8] data f rom matlab eq.[s=5.7] -40 -35 -30 -25 -20 -15 -10 -5 0 50 100 150 200 250 300 350 te [°c] c oo lin g c ap ac ity [w ] tecumseh thb 1360y[s=6.1] danf oss nl6f[s=6.13] embraco nb t1114z[s=6.2] donper ek1114cza[s=6.3] data f rom matlab eq.[s=6.13] -40 -35 -30 -25 -20 -15 -10 -5 0 50 100 150 200 250 300 350 400 te [°c] c oo lin g c ap ac ity [w ] danf oss tls7f[s=6.49] donper l58cz[s=6.5] data f rom matlab eq.[s=6.49] -40 -35 -30 -25 -20 -15 -10 -5 0 50 100 150 200 250 300 350 400 450 500 te [°c] co ol in g ca pa ci ty [w ] donper ek1118cza [s=7.2] donper l72cz [s=7.2] danf oss nl7f [s=7.27] data f rom matlab eq. [s=7.27] -40 -35 -30 -25 -20 -15 -10 -5 0 50 100 150 200 250 300 350 400 450 te [°c] q e [w ] electrolex g l80aa[s=8.1] embraco nb 1116z[s=8.1] kk ae1370y[s=8.12] data f rom matlab eq.[s=8.1] -40 -35 -30 -25 -20 -15 -10 -5 0 50 100 150 200 250 300 350 400 450 te [°c] c oo lin g ca pa ci ty [ w ] tecumseh aez1365y[s=8.8] tee ae196yp[s=8.99] danf oss fr10f[s=9.05] acc g q y90aa[s=9.05] data f rom matlab eq.[s=9.05] [10-g] [10-h] [10-i] [10-j] [10-k] [10-l] louay abd alazez mahdi al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 89106 (2015) 100 -40 -35 -30 -25 -20 -15 -10 -5 0 50 100 150 200 250 300 350 400 450 500 550 te [°c] c oo lin g ca pa ci ty [w ] data f rom matlab[s=9.93] electroles g l99aa[s=9.93] -40 -35 -30 -25 -20 -15 -10 -5 0 50 100 150 200 250 300 350 400 450 500 550 te [°c] data f rom matlab eq.[s=11.15] daf oss nl11f[s=11.15] c oo lin g ca pa ci ty [w ] -40 -35 -30 -25 -20 -15 -10 -5 0 25 50 75 100 te [c] p ow er [ w ] data f rom matlab[s=2.42] eletrolex g d24aa[s=2.42] -40 -35 -30 -25 -20 -15 -10 -5 0 25 50 75 100 125 te [°c] p ow er [ w ] electrolex g d30aa[s=3.05] data f rom matlab eq.[s=3.05] -40 -35 -30 -25 -20 -15 -10 -5 0 20 40 60 80 100 120 140 160 180 200 te [°c] p o w er [w ] electrolex g d36aa[s=3.58] acc g q y35aa[s=3.66] tecumseh thb 1335y[s=3.58] data f rom matlabeq.[s=3.58] -40 -35 -30 -25 -20 -15 -10 -5 0 25 50 75 100 125 150 175 te [°c] p ow e r [w ] kilthorn kirby ae1327y[s=3.9] acc g q y40aa[s=4.01] data f rom matlab eq.[s=4.01] electrolex g l40aa [s=4.01] acc g vm40aa[s=4.07] kulthorn kirby ae1330y[s=4.08] [10-m] [10-n] fig. 10-a to 10-n. show the deviation of the calorimeter data from correlated data for cooling capacity for the range of swept volume [2.42 to 11.15] cm3. [11-a] [11-b] [11-c] [11-d] louay abd alazez mahdi al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 89106 (2015) 101 -40 -35 -30 -25 -20 -15 -10 -5 0 25 50 75 100 125 150 175 200 225 te [°c] po w er [ w ] tecumseh thb 1360y[s=6.13] danf oss nl6f[s=6.13] data f rom matlab eq.[s=6.13] -40 -35 -30 -25 -20 -15 -10 -5 0 25 50 75 100 125 150 175 200 225 250 te [°c] p ow er [w ] acc g vm66aa[s=6.6] electrolex g l70aa[s=6.64] acc ln70an[s=6.64] data f rom matlab[s=6.64] -40 -35 -30 -25 -20 -15 -10 -5 0 25 50 75 100 125 150 175 200 225 te [°c] p ow er [ w ] kulthorn kirby ae1360y[s=6.91] danf oss fr7.5f[s=6.93] acc g vy66aa [s=7.0] data f rom matlab eq.[s=7] -40 -35 -30 -25 -20 -15 -10 -5 0 25 50 75 100 125 150 175 te [°c] p ow er [ w ] electrolex g l45aa[s=4.56] kulthorn kirby ae 1335y[s=4.6] data f rom matlab[s=4.6] -40 -35 -30 -25 -20 -15 -10 -5 0 25 50 75 100 125 150 175 200 te [°c] p ow er [ w ] kulthorn kirby ae1340y[s=5.11] electrolex g l50aa[s=5.12] tecumseh thb 1350y[s=5.2] data f rom matlab eq.[s=5.12] -40 -35 -30 -25 -20 -15 -10 -5 0 25 50 75 100 125 150 175 200 te [°c] p ow e r [w ] data f rom matlab eq.[s=5.7] danf oss tls6f[s=5.7] acc g vm57aa[s=5.7] [11-e] [11-f] [11-g] [11-h] [11-i] [11-j] louay abd alazez mahdi al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 89106 (2015) 102 -40 -35 -30 -25 -20 -15 -10 -5 0 25 50 75 100 125 150 175 200 225 250 275 300 te [°c] p ow er [ w ] electrolex g l75aa[s=7.39] acc g l80aa[s=7.39] acc g vy75aa[s=7.39] data f rom matlab eq.[s=7.39] acc g vy75aa[s=7.52] -40 -35 -30 -25 -20 -15 -10 -5 0 50 100 150 200 250 300 350 te [°c] po w er [ w ] data f rom matlab eq.[s=9.93] electrolex g l99aa[s=9.93] -40 -35 -30 -25 -20 -15 -10 -5 0 50 100 150 200 250 300 350 te [°c] po w er [ w ] data f rom matlab eq.[s=11.15] danf oss nl11f[s=11.15] -40 -35 -30 -25 -20 -15 -10 -5 0 25 50 75 100 125 150 175 200 225 250 275 300 te [°c] p ow e r [w ] electrolex g l80aa[s=8.1] danf oss nl9f[s=8.35] data f rom matlab eq.[s=8.1] data f rom matlab eq.[s=8.35] -40 -35 -30 -25 -20 -15 -10 -5 0.25 0.65 1.05 1.45 1.85 2.25 te [°c] r ef rig er an t m as s flo w ra te [k g/ hr ] data f rom matlab eq.[s=2.42] electrolex g d24aa[s=2.42] -40 -35 -30 -25 -20 -15 -10 -5 0 0.5 1 1.5 2 2.5 3 te [°c] r ef rig er an t m as s flo w ra te [k g/ hr ] data f rom matlab eq.[s=3.05] elctrolex g d30aa [s=3.05] [11-k] [11-l] [11-m] [11-n] fig. [11-a to 11-n]. show the deviation of the calorimeter data from correlated data for power consumption for the range of swept volume [2.42-11.15] cm3. [12-a] [12-b] louay abd alazez mahdi al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 89106 (2015) 103 -40 -35 -30 -25 -20 -15 -10 -5 0 0.5 1 1.5 2 2.5 3 3.5 4 te [°c] r e fri ge ra nt m as s flo w ra te [ kg /h r ] electrolex g d36aa[s=3.58] data f rom matlab eq.[s=3.58] -40 -35 -30 -25 -20 -15 -10 -5 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 te [°c] r e fr ig er a nt m a ss fl o w ra te [k g/ h r] data f rom matlab eq.[s=4.01] electrolex g l40aa [s=4.01] -40 -35 -30 -25 -20 -15 -10 -5 0 1 2 3 4 5 te [°c] r ef rig er an t m as s flo w ra te [k g/ hr ] electrolex g l45aa[s=4.56] data f rom matlab eq.[s=4.56] -40 -35 -30 -25 -20 -15 -10 -5 0 1 2 3 4 5 6 te [°c] r ef rig er an t m as s flo w ra te [k g/ hr ] danf oss tls5f[s=5.08] data f rom matlab eq.[s=5.08] -40 -35 -30 -25 -20 -15 -10 -5 0 1 2 3 4 5 6 te [°c] r ef rig er an t m as s flo w ra te [k g/ hr ] data f rom matlab eq.[s=5.7] danf oss tls6f[s=5.7] -40 -35 -30 -25 -20 -15 -10 -5 0 1 2 3 4 5 6 7 te [°c] danf oss nl6f[s=6.13] tecumseh thb 1360y[s=6.1] data f rom matlab[s=6.13] r ef rig er an t m as s flo w ra te [k g/ hr ] [12-c] [12-d] [12-e] [12-f] [12-g] [12-h] louay abd alazez mahdi al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 89106 (2015) 104 -40 -35 -30 -25 -20 -15 -10 -5 0 1 2 3 4 5 6 7 te [°c] r ef rig er an t m as s flo w ra te [k g/ hr ] danf oss tls7f[s=6.49] te [°c] data f rom matlab eq.[s=6.49] -40 -35 -30 -25 -20 -15 -10 -5 0 1 2 3 4 5 6 7 8 te [°c] r ef rig er an t m as s flo w ra te [ kg /h r] danf oss nl7f[s=7.27] data f rom matlab eq.[s=7.27] -40 -35 -30 -25 -20 -15 -10 -5 0 1 2 3 4 5 6 7 8 9 te [°c] r ef rie ra nt m as s flo w ra te [ kg /h r] electrolex g l80aa[s=8.1] data f rom matlab eq.[s=8.1] -40 -35 -30 -25 -20 -15 -10 -5 0 1 2 3 4 5 6 7 8 9 te [°c] danf oss nl9f[s=8.35] dta f rom matlab eq.[s=8.35] r ef rie ra nt m as s flo w ra te [ kg /h r] -40 -35 -30 -25 -20 -15 -10 -5 0 1 2 3 4 5 6 7 8 9 10 te [°c] r ef rig er an t m as s flo w ra te [ kg /h r] electrolex g l99aa[s=9.93] data f rom matlab eq.[s=9.93] -40 -35 -30 -25 -20 -15 -10 -5 0 1 2 3 4 5 6 7 8 9 10 11 te [°c] data f rom matlab eq.[s=11.15] daf oss nl11f[s=11.15] r ef rig er an t m as s flo w ra te [ kg /h r] [12-i] [12-j] [12-k] [12-l] [12-m] [12-n] fig. [12-a to 12-n]. show the deviation of the calorimeter data from correlated data for refrigerant mass flow rate for the range of swept volume [2.42-11.15] cm3. louay abd alazez mahdi al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 89106 (2015) 105 5. conclusion semi-empirical models were found to represent household compressors. first: the calorimeter data which are correlated (according to ari standard 540-90) which must involve to coefficients to cover the swept volume range (2.24-11.15) cm3 at constant condensing temperature 54.4 ℃ and evaporating temperature range (-35 to -10)℃, by using matlab softwaresurface fitting method as in equations (1),(2), and (3). the models represent the cooling capacity, power consumption, and refrigerant mass flow rate with ∓15% deviation. second: another correlations as quick selection was found depending on the label power consumption and according to shrae standard 23-1993, in order to find the household compressor specifications, like swept volume and cooling capacity as in equations (4), (5), and (6). list of symbols a1,a2,…,a9 constant ari air conditioning and refrigeration institute ashrae american society of heating, refrigerating and airconditioning engineers b1,b2,…,b9 constant c1,c2,…,c9 constant mr refrigerant mass flow rate kg/hr p power consumption watt qe cooling capacity watt r2 goodness of fit s swept volume cm3 te evaporator temperature ℃ 6. references [1] duggan.m.g., hundy.c.f.,and lawson.s. "refrigeration compressor performance using calorimeter and flow rater techniques", purdue university, int. compressor engineering conference,1988 . [2] cavallini, doretti, longo, and rossetto."thermal analysis of hermetic reciprocating compressor" , purdue university, int. compressor engineering conference,1996. [3] mackensen, klein, and eindl,"characterization of refrigeration system compressor performance", purdue university, int. compressor engineering conference, 2002. [4] kim,and bullard. "thermal performance analysis of small hermetic refrigeration and air conditioning compressors" international journal of jsme, series b, vol.45, no.4, 2002. [5] jähnig, reindl, and klein, “a semi-empirical method for representing domestic refrigerator/freezer compressor calorimeter test data”, ashrae transactions, 106 (2000),pp 122-130. [6] cezar o. r. negrao, raul h. erthal, diogo e. v. andrade, and luciana w. silva”embraco an algebraic model for transient simulation of reciprocating compressors “. [7] holmn. j.p." experimental methods for engineers", eight editions. mc grawhill company.2010. [8] a.r.i. standard 540-99, “positive displacement refrigerant compressors and compressor units”. air-conditioning and refrigeration institute, 1999. [9] ashrae/ansi standard 23-1993, “methods of testing for rating positive displacement refrigerant compressors and condensing units”, american society of heating, refrigerating and air-conditioning engineers, inc., atlanta, 1993. ������"ي �� ا #$%&��()' ا*+��د11�%$' ا�0/ارز#, ا�� )2015( 89-106، 234' 4، ا 106 ���ت وا� � �ات�ا���د ���د�ت ا�داء �� �ا� ا� ����� ا���� ������ �دا ��! ا� ����ت ا�� ***��+ � � ا� ��* ** � �د ا( ���) ' �& * �%ي � � ا������#�ى *،**،***'(5(675(&��(' ا*+��/;)'/ :89 ا/*5<� ا�%7#�' ا � ا?�5><و6,�>�� louayalkaesy@gmail.com:ا � ا?�5><و6,�>�� emad_1955_emad@yahoo.com :ا ��� ا?�5><و6,<ا�: laith.ismael@ymail.com �,� ا� �$7g>aت ا�&d# d(*e? '�*f ا��c#7ت ا�>%7ر�' ا�a+)<ة >�9&��)' ا(>*7دا إ�h i)767ت ا�*&�ھsه ا�&�7د?ت ذات ، 8p ا�%7د #�7د?ت أداء #7' �$m/اkl ا �رھ7 : '<h7e uv5# ارة>w ';ر�h '(5�>#?ا ��>�<�#\/�' ) ١٠ا�i ٣٥(d #\/�' ودر;' w<ارة #�0< # ٥٤.٤ e >a/ا7h yh?(>*7د ا�7x(e/p iت #"(9' ا `#76>h ام�0<)7hبcp7# ، /ي ھs�� ا�>�<��cd7# '$<g ef اp ل���'، وا(>+cك ا�7h:'، و#��>�<��رة اx�± و7gن #��ل ا�2)/د . r-134aھsه ا�&�7د?ت jv&p ا ��' و ٧٢٪ و�&7x# jvر6' ١٥�>�<��رة اx$� kl7o>�9# 7ن(hك ٥٠c+<)? >�9# 7ن(h 7:' وh��h$<g ef)7ن ٢٥ا<� >�9#' ��>�<� .cd7# ا pppppp&g7 ام�0<pppppp)7h ء و,f7pppppp5&��/ppppppw' ا�7pppppp%�? kl7ppppppmد ا�8pppppp%2 ا ipppppp$ 'pppppp<�v&�8ppppppp إ�%7ppppppد #�7ppppppد?ت أداء �$ppppppm/ا7pppppp&< ?7h klد $ipppppp ا�pppppp&(x' ا �pppppp�>�<��ل ;<�7ppppppن cd7pppppp# 'pppppp$<g اpppppp�#و 'pppppp���>�<��وھsppppppا ، ھsppppppا ا�8pppppp%2 ا�&f7pppppp5,ء ��pppppp9' ا�ppppppf>�# 8<pppppp� kl7ppppppm' ا�pppppp:7h' اpppppp�� 7راpppppp)<qا ��>pppppp(7 �$ppppppp)?7h kl7pppppppm>*7د ا�7pppppppx(e/p ipppppppت ashrae ى�ppppppp&� klا/pppppppm�ا�ippppppp ٢.٤٢(ا�7(x(ppppppp)' ا�>ppppppp /&%# ,ppppppphsp ,ppppppp' وا(dppppppp# '�ppppppp ا7ppppppp%wم ا ١١.٥١ (cm3. 93-101 al-khwarizmi e ngineering journal,vol. 12, no. fabrication of carbon nanotube reinforced al nanocomposites by coprecipitation process department of materials engineering (received http://dx.doi.org/10.22153/kej.2016.08.001 abstract in this research, the effect of multi nanocomposites has been investigated. mwcnts were fabricated using coprecipitation process and followed by spark plasm revealed a good crystallinity of sintered nanocomposites solid solution. density, vickers microhardness, fracture toughness and fracture strength have been measured sintered samples. the results show that the relative density, microhardness and fracture strength of nanocompos significantly improved at low content nanocomposites has adversely affected leads to agglomeration in the nanocomposites. al 2o3-cr2o3 solid solution that actually fracture toughness of al2o3/cr2o3-mwcnts nanocomposites was enhanced content. keywords: al2o3/cr2o3 nanocomposite, mwcnts, coprecipitation 1. introduction the field of the nanocomposite materials has taken a lot of interesting and close engineers and scientists in recent years [1]. nanocomposite materials can be considered of solid structures with nanometer scale dimensional repeat distances between the various phases that constitute the structure. the most common methods for processing nanocomposites are mechanical alloying, coprecipitation process, sol gel synthesis and by thermal spray synthesis [1,2]. the increasing attention in the solid solutions of ceramic oxide materials is mostly related thermal and chemical stability and their structural characteristics [3]. alumina/chromia (al2o3/cr2o3) is a simple binary system, as shown in fig. 1. [3,4]. al and cr2o3 are the stable sesquioxides ngineering journal,vol. 12, no. 4, p.p. 93101 (2016) fabrication of carbon nanotube reinforced al2 nanocomposites by coprecipitation process hussein alaa jaber department of materials engineering/ university of technology e-mail: husseinaj@yahoo.com (received 18 april 2016; accepted 8 august 2016) http://dx.doi.org/10.22153/kej.2016.08.001 multi-walled carbon nanotubes (mwcnts) on the alumina/chromia has been investigated. al 2o3/cr2o3-mwcnts nanocomposites with variable mwcnts were fabricated using coprecipitation process and followed by spark plasma sintering revealed a good crystallinity of sintered nanocomposites samples and there was only one phase presence of al solid solution. density, vickers microhardness, fracture toughness and fracture strength have been measured sintered samples. the results show that the relative density, microhardness and fracture strength of nanocompos low contents of cr2o3 and mwcnts. the increase of mwcnt due to increasing the tangle and interaction of mwcnts leads to agglomeration in the nanocomposites. increasing of cr2o3 content in nanocomposites solid solution that actually requires the high sintering temperature to achieve good densification mwcnts nanocomposites was enhanced by increasing the carbon nanotube nanocomposite, mwcnts, coprecipitation process and spark plasma sintering (sps). the field of the nanocomposite materials has and close observation of scientists in recent years [1]. nanocomposite materials can be considered of solid structures with nanometer scale dimensional repeat distances between the various phases that constitute the structure. the most common methods for processing nanocomposites are pitation process, soland by thermal spray synthesis [1,2]. solid solutions of related to their thermal and chemical stability and their structural ) is a simple binary system, as shown in fig. 1. [3,4]. al2o3 sesquioxides having the same corundum crystal structure ( system with the al3+ and cr thirds of the octahedral interstitial sites). at high temperature, they form complete substitutional solid solution without consistence over the entire composition range [3,5]. al cr2o3 system is great interest refractoriness and chemical stability at high temperatures. also, this system has superior mechanical properties and good thermal shock resistance [4,6]. densification behavior, strength, modulus of rupture and irregular dependency relianc however, low fracture toughness of ceramics still cannot match the command of many practical fields, which greatly limits its applications [7]. recent researches are incorporation of carbon nanotubes (cnts) i ceramic matrix composites in order to improve al-khwarizmi engineering journal (2016) o3/cr 2o3 nanocomposites by coprecipitation process lumina/chromia (al2o3/cr2o3) nanocomposites with variable contents of cr2o3 and a sintering. xrd analysis one phase presence of al2o3-cr2o3 solid solution. density, vickers microhardness, fracture toughness and fracture strength have been measured in the sintered samples. the results show that the relative density, microhardness and fracture strength of nanocomposites are mwcnt’s content in the cnts with each other, which nanocomposites increases formation of sintering temperature to achieve good densification. the increasing the carbon nanotube and spark plasma sintering (sps). same corundum crystal structure (hexagonal and cr3+ ions taking two thirds of the octahedral interstitial sites). at high temperature, they form complete substitutional consistence of any eutectic over the entire composition range [3,5]. al2o3– system is great interest due to of its high fractoriness and chemical stability at high temperatures. also, this system has superior mechanical properties and good thermal shock ensification behavior, strength, modulus of rupture and hardness exhibited dependency reliance on each other [5,6]. however, low fracture toughness of ceramics still cannot match the command of many practical fields, which greatly limits its applications [7]. devoted to the possible incorporation of carbon nanotubes (cnts) in ceramic matrix composites in order to improve hussein alaa jaber al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 93101(2016) 94 their performance [8,9]. cnts have attracted a great attention as potential strengthening and toughening materials in industrial applications due to their particular structure, low density, high strength and toughness and excellent corrosion resistance [7,9]. fig. 1. phase diagram of al2o3–cr2o3 system [3]. many studies have studied the mechanical properties, especially the toughness, of ceramics through incorporating cnts in ceramic matrix. for example, echeberria et al. [8] demonstrated that 0.1 wt% of mwcnts or single walled carbon nanotubes (swcnts) added to the zirconia toughened alumina (zta) composites, and followed by spark plasma sintering at 1520°c, is enough for obtaining to high hardness and fracture toughness. ahmad et al. [10] studied the influence of the carbon nanotubes content on the mechanical properties of al2o3 that fabricated by hot-pressing. they reported a 32% increase in fracture toughness and 12% increase in hardness were observed with 2 wt% of cnts additive, when compared with the monolithic al2o3. siegel et al. [11] reported a 24% increase in fracture toughness of al2o3 with additions of 10 vol% mwcnts. the present work aims to study the effect of various amounts of multi-walled carbon nanotubes on the some mechanical properties of al 2o3/cr2o3 nanocomposites. coprecipitaion process is used to disperse mwcnts homogeneously in al2o3/cr2o3 solid solution matrix by entrapping the dispersed carbon nanotubes in the gel network. the prepared nanocomposites samples are densified using a new sintering process such as spark plasma sintering. density, vickers microhardness, fracture toughness and fracture strength of the al 2o3/cr2o3-mwcnts nanocomposites as a function of the mwcnts and cr2o3 contents are investigated. 2. experimental work aluminum nitrate (al(no3)3.9h2o, >98%, alfa aesar, uk) and chromium nitrate (cr(no3)3.9h2o, 99%, alfa aesar, uk) were used as precursors for preparing of alumina/chromia (al2o3/cr2o3) nanocomposites. multi-walled carbon nanotubes (mwcnts) having dimensions of about (20-30) nm in outer diameter, (0.5-10) µm in length and density of 1.85 g/cm3, (provided from sigma–aldrich, uk), was used as reinforcement material. ceramic nano-composites of al2o3 with two weight percentages of cr2o3 (10 and 20) wt% were prepared using coprecipitation process. in this process, aluminum nitrate and chromium nitrate were separately dissolved in solution of (distilled water/ethanol) (1/1) wt% with a molar concentration of 0.5 m for each one. appropriate amount of chromium nitrate solution have been mixed with aluminum nitrate solution for obtaining two solutions with different percentages of cr2o3 in al2o3 (al2o3 -10wt% and -20wt% cr2o3). the solutions were stirring at 250 rpm in a magnetic stirrer for 1 hour at 120°c. the mwcnt was dispersed in small amount of ethanol solution and then added to the alumina/chromia solutions during stirring process. the weight fraction of mwcnts was controlled as (0, 1.5, 3 and 4.5) wt% from the total weight of the samples as shown in table (1). the mixed solutions were ultrasonicated for 20 min to avoid agglomeration and more homogenization of carbon nanotubes in alumina/chromia solutions. addition of ammonium hydroxide drops to the total mixed solutions until alumina/chromiamwcnts gel was formed. the prepared gels have been filtered, and calcined at 500°c for 4 hours in an electrical furnace. the calcined gels were ground using mortar and pestle. the samples sintering were carried out by spark plasma sintering (sps) technique. the sintering temperature was 1500°c at a heating rate of 100°c/min, the applied pressure is 80 mpa and the holding time is 5 min. the dimensions of sintered samples were 20 mm in diameter and 5 mm in thickness. a flow diagram for the experimental work is shown in fig. 2. characterizations of the sintered specimens were evaluated using x-ray diffraction (xrd), scanning electron microscope (sem). apparent hussein alaa jaber al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 93101(2016) 95 density of the sintered specimens was determined using archimedes method, and the relative density was calculated by dividing the apparent density by the theoretical density. in this work, 3.94 g/cm3, 5.21 g/cm3 and 1.85 g/cm3 were assumed for the theoretical density of al 2o3, cr2o3 and mwcnts respectively. fig. 2. flow chart for the experimental part of this work. the hardness was measured using a vickers microhardness testing machine (mitutoyo hm 122) at load of 9.81 n for 15 sec. indentation diagonal lengths and crack lengths extending from the corners of the vickers indentations were determined using optical microscopy for fracture toughness (k1c) measurements. the fracture toughness is calculated using shetty et al. method as in equation (1) [12]. k�� = 0.0319 p d . l�/� … �1� where: k1c = fracture toughness (mpa.m0.5), p = applied load (n), d = vickers indent diameter (m) and l = crack length (m). the fracture strength is determined using the diametrical compression disc test and the equation (2) was applied to calculate the strength of the samples [13]: σ� = 2 f π d t … �2� where: σs = fracture strength, f = applied load (n), d = diameter of the disc (mm) and t= thickness of the disc (mm). table 1, preparation of nanocomposite samples. sample composition mwcnts additions al 2o3-10wt% cr2o3 (0, 1.5, 3 and 4.5) wt% al 2o3-20wt% cr2o3 (0, 1.5, 3 and 4.5) wt% 3. results and discussion 3.1. x-ray diffraction (xrd) x-ray diffraction patterns for sintered al2o310 wt% cr2o3 nanocomposite with different mwcnts content (0 and 3) wt% are chosen in this test as shown in fig. 3-a and -b respectively. it has been shown that all peaks were matched of α-al 2o3 with small shifting, corresponding to jcpds card no 43-1484. as known, the addition of cr2o3 in the al2o3, the distances between aal 2o3 planes increase and there is a shift of all the peaks conforming to the pure alumina which indicates the formation of solid solution [3-5]. from these figures also, it is clear that the xrd pattern for the nanocomposite with 0 wt% of mwcnt exhibit almost similar pattern to that with 3 wt% of mwcnt and there are no new phases appearing. this indicates the carbon nanotubes are stable at elevated temperature during the sintering process and did not reacted with al2o3 and cr2o3. fig. 3-b also reveals only the typical crystalline peaks from alumina and no peaks from carbon nanotubes were observed. the diminishing of mwcnts peaks are possibly due to the high crystallinity of al2o3/cr2o3 solid solution phase and low contents of cnts in the nanocomposites. hussein alaa jaber al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 93101(2016) 96 fig. 3. xrd pattern of the sintered al2o3-10wt% cr 2o3 samples with different mwcnts contents, (a) 0 wt% and (b) 3 wt%. 3.2. relative and apparent density the effect of various carbon nanotubes content on the relative density of sintered nanocomposites can be observed in fig. 4. fig. 4 indicates that the relative density of al2o3-10 wt% cr2o3 samples is slightly increased to reach the maximum value (99.5%) with the addition of 1.5 wt% mwcnts, and then decreases for further increase in the mwcnts content. when the content of carbon nanotubes is less, carbon nanotubes may be well adhered and dispersed within the matrix without apparent damage to the microstructure and morphology. however, the increase of mwcnts content in nanocomposites the relative density decreases. it is reported that the increasing presence of cnts in a ceramic matrix play a negative role and act same as an impurity, which restrains the flow of matrix through the sintering stage, hence accounts inhibits the densification of the nanocomposite and decrease in the relative density [7,14]. from fig. 4 also, it is seen that the al2o310wt% cr2o3 nanocomposites samples have higher values of relative density, at different carbon nanotube content, than al2o3-20wt% cr2o3. this is because the chromia has a higher melting point (2440°c) than alumina (2070°c), therefore with increase the chromia contents in alumina; the final composites will need a higher sintering temperature to achieve good densification. fig. 4. effect of mwcnts addition on the relative density of al2o3/cr 2o3 nanocomposites samples. fig. 5. effect of mwcnts addition on the apparent density of al2o3/cr 2o3 nanocomposites samples. fig. 5 reveals the apparent density versus mwcnts additive for sintered nanocomposites samples of (al2o3-10 wt% and -20 wt% cr2o3). it has been shown that the apparent density of al 2o3/cr2o3-mwcnts nanocomposite samples is slightly decreased with increasing the carbon nanotubes contents. the apparent density of the al 2o3-10 wt% cr2o3 samples is decreased from (3.98 to 3.79) g/cm3, and from (4.08 to 3.84) hussein alaa jaber al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 93101(2016) 97 g/cm3 for al2o3-20 wt% cr2o3 nanocomposite samples. as known, the porosity is inversely proportionate with the density of composites. on the other hand, the tangle and interact of carbon nanotubes with each other through van der walls force, which increases the probability of the cnts agglomeration in the nanocomposites, and thereby makes it difficult to acquire a homogeneous dispersion of cnts in the ceramic matrix. the clustering of cnts may play a negative role like a pore. the pore density extremely influences on the densification of the ceramic composites [14]. mass transportation and elimination of pores through bulk diffusion are two important factors that determine the final density during the consolidation process of the alumina ceramics. it is believed that the high values of carbon nanotubes into the al2o3/cr2o3 matrix have adversely affected and this resulted in nanocomposites with lower density [10]. from fig. 5 also, it has been shown that the nanocomposite samples from al2o3-10 wt% cr2o3 having higher values of apparent density than al2o3-20 wt% cr2o3, at different carbon nanotube content. this is attributed to increasing the cr2o3 content that has higher specific gravity of (5.22) as compared to al2o3 (3.94) [5]. 3.3. microhardness the microhardness of a ceramic material is an important mechanical property because it relates how much the material will in elastically deform when a surface load is applied. because, the indentation diameters of microhardness vickers tester for sintered samples are very small. the light optical microscope assisted computer program is used for analysis the indentation images and calculates the vickers microhardness of the sintered samples. the vickers microhardness values of the sintered al2o3/cr2o3 nanocomposites samples as a function of mwcnt content are shown in fig. 6. it is clear that samples of al2o3-20 wt% cr2o3 have higher values of microhardness than al2o3-10 wt% cr2o3 at different carbon nanotubes content. this is attributed to effects of the formation of chromium (iii) oxide solid solution in aluminium (iii) oxide. since, both the oxides (al2o3 and cr2o3) form complete substitutional solid solution over the whole composition range. the hardness is increased by microstructural modification that caused the compressive stress generated by the substitution of bigger cr3+ ion (0.076 nm) in place of smaller al3+ ion (0.068 nm). the localized compressive stress, especially on the sample surface, helps to the microstructure strengthening of nanocomposites, and then the microhardness increases by this effect [5,15]. furthermore, it is well known that chromia has hardness slightly higher than alumina. hence, that there is increasing increment in microhardness of the nanocomposite with increasing content of chromia [16]. fig. 6. vickers microhardness of the al2o3/cr 2o3 nanocomposite samples as a function of the mwcnts content. the microhardness values of al2o3/cr2o3 nano-composites also affected with the carbon nanotube contents. fig. 6 also shows that the microhardness values of the al2o3-20 wt% cr2o3 nanocomposite samples decreases gradually with increasing the carbon nanotube contents. while the microhardness value of al2o3-10%cr2o3 samples increases with 1.5 wt% of mwcnts addition, then it decreases gradually with increasing the carbon nanotube content. the increase in the carbon nanotubes content above the optimal value impedes the densification of the nanocomposite, and hence considerations for the decrease in the microhardness. because the hardness values are highly correlated with relative density and porosity, thereby reducing the number of defects in a sample is a common way of increasing its microhardness [14,17]. 3.4. fracture toughness fracture toughness of sintered nanocomposites is calculated according to the shetty et al. cracklength method. the effect of carbon nanotube addition on fracture toughness of the sintered hussein alaa jaber al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 93101(2016) 98 nanocomposites samples of (al2o3-10 wt% and 20 wt% cr2o3) is shown in fig. 7. from this figure, it is obvious that by increasing the mwcnts content, the fracture toughness of al 2o3-10 wt% cr2o3 and al2o3-20 wt% cr2o3 is increased. this increasing in fracture toughness is attributed to increasing the presence of the mwcnts secondary phase and solid solution of al 2o3/cr2o3 in the microstructure of such samples. fig. 7. fracture toughness of the al2o3/cr 2o3 nanocomposites as a function of mwcnts content. the increases in quantity of carbon nanotubes in the nanocomposites may make in an easier convey of the stress and thus could account for the considerable increase in the fracture toughness [14]. furthermore, the residual pores located between the agglomerated multi-walled carbon nanotubes in the nanocomposites, especially at high cnts content, could function as crack arrestors, resulting to the increase of observed fracture toughness [18]. 3.5. fracture strength fig. 8 shows the effect of carbon nanotubes addition on the fracture strength of the sintered nanocomposites samples of (al2o3-10 wt% and 20 wt% cr2o3). it is found that the addition of carbon nanotube is highly improving in the fracture strength of al2o3-10wt% cr2o3 than al 2o3-20wt% cr2o3 nanocomposite samples. in the al2o3-10wt% cr2o3 nanocomposite samples, the fracture strength increases rapidly from 88.3 mpa to 106.8 mpa when addition of 1.5 wt% of mwcnt, then it decreases gradually with increasing the mwcnts content. a sharp increase in the fracture strength can be related to enhancement in the relative density of nanocomposites. the increase in the mechanical properties at low carbon nanotube additions can be associated with the well dispersed of mwcnts within the al2o3/cr2o3 matrix and strong interfacial connection between mwcnts and the matrix. the improvement in relative density with fewer pores, which leads to increasing the particles bonding and consequent strength enhanced [10]. the decrease in the fracture strength at higher carbon nanotube content in nanocomposites may be due to the arising difficulties of densification with higher concentrations of cnts. furthermore, the generation of thermally induced residual stresses after sintering of nanocomposite samples is another factor that may have contributed to the lowering in the strength. the mismatch in the thermal expansion coefficient between the matrix al 2o3/cr2o3 of (~ 8.1×10−6/°c), and mwcnts (~ 2.7×10−6/°c) could produce residual stresses around the dispersed carbon nanotubes, which could result the micro cracks, which consequently results in the lowering of mechanical properties. besides, it is accepted that the cnts existing in the grain boundaries act as spatial barriers to inhibit closing up of grains [14,18]. fig. 8. effect of mwcnts addition on the fracture strength of al2o3/cr 2o3 nanocomposites samples. fig. 9 shows the sem micrographs of fracture surfaces of al2o3-10 wt% cr2o3 nanocomposite samples with different contents of mwcnts. nanocomposite sample without mwcnts, fig. 9-a, the sem micrograph illustrates that the fracture proceeded mostly by intergranular and hussein alaa jaber al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 93101(2016) 99 this can be associated with occurring some of grain growth during the consolidation process. on other hand, it is observed that the addition of mwcnts to the nanocomposite leads to decrease in the grain size, this clearly shown in fig. 9-b and -c. the addition of the mwcnts to the nanocomposites, the fracture surface becomes slightly rough and exhibit two fracture modes (intergranular and transgranular) fracture. fig. 9. sem micrographs of fracture surface of al 2o3-10 wt% cr 2o3 nanocomposite samples with different mwcnts content: (a) 0 wt%, (b) 1.5 wt% and (c) 4.5 wt%. the great irregularity exhibited in the fracture surface of nanocomposites with increasing of mwcnts addition leads to increase in fracture toughness of the samples. this is because the high deflection angles lead to increment the crack path tortuosity, which crack propagation encounters with a large obstruction [8,19]. 4. conclusions al 2o3/cr2o3-mwcnts nanocomposites were successfully fabricated using the coprecipitation process and followed by spark plasma sintering technique. mwcnts were well despaired within the al2o3/cr2o3 nanocomposites samples by coprecipitation process at low carbon nanotube contents. the relative density, microhardness and fracture strength of the al2o3-10wt% cr2o3 nanocomposites were enhanced with addition of 1.5 wt% mwcnts. the increasing of carbon nanotubes content in the nanocomposites have adversely affected due to increasing the tangle and interaction with each other via van der walls force during the coprecipitation process, which increases the probability of the mwcnts agglomeration in the nanocomposites. decreasing in the relative density and fracture strength of al 2o3/cr2o3-mwcnts nanocomposites samples with increasing of the cr2o3 content is attributed to increased formation of al2o3-cr2o3 solid solution that actually absorbs extra heat energy and requires a higher sintering temperature to achieve good densification. fracture toughness of al 2o3/cr2o3 nanocomposites was enhanced by increasing the carbon nanotube content. 5. references [1] subhranshu sekhar samal and smrutisikha bal, "carbon nanotube reinforced ceramic matrix compositesa review", journal of minerals & materials characterization & engineering, vol. 7, no. 4, pp. (355–370), 2008. 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[17] l. w. hankla, "mechanical properties of particulate-reinforced boron carbide composites", m.sc. thesis, department of mechanical engineering, college of engineering, university of south florida, 2008. [18] s. zhu, w. g. fahrenholtz, g. e. hilmas, s. c. zhang, e. j. yadlowsky and m. d. keitz, "microwave sintering of a zrb2–b4c particulate ceramic composite", composites: part a: applied science and manufacturing, vol. 39, pp. (449–453), 2008. [19] kai yang, xiaming zhou, huayu zhao, shunyan tao, " microstructure and mechanical properties of al2o3–cr2o3 composite coatings produced by atmospheric plasma spraying", surface & coatings technology, vol. 206, pp. (1362–1371), 2011. ��ء ���� �� )2016( 93-101، "! � 4، ا���د����12 ا���ارز � ا����� � ا���� 101 )�ا'&�ت $�$�#� ) �*+al 2o3/cr 2o3 � 0 ا�/�ر��ن ا���$�#� �-�)��ام �����$-� ���� 0 ا�)�� ��ء ������ ��� ھ���� ا���اد /��� ا�$#"!� ا� ����� husseinaj@yahoo.com%&)و �ا�+)*� ا(� : �"�� ا� al):)و"�# /ا��"��#ا�; " )ا:+#ت &#&�*� "mwcnts ( 7(* 7�8 ھ6ا ا�+45 درا�� 2#3�) ا1#�0 ا&#-�/ ا��#ر-�ن ا��#&�*� 2o3/cr2o3) . �3 4�< #��3<��= " )ا:+#ت &#&�*� "7 ا(��"/#��� ا� )��/ و3@�mwcnts #bو cr2o3ا&#-�/ ا��#ر-�ن ا��#&�*� "= "5 �*#ت "a @?� "7 :)و"@�c ام�a �#�� ا� @+�� -#�+fز"#@�c . 7" �"#$ن ط�ر وا>� �@�5@�ل ا���ت ا�� )ا:/ ا��#&�ي "= 3#����ة �!��� -+@�ر*� ����د ا(k!� ا��< l�@53 mn:al 2o3/cr2o3 . �3 �0#o�س ا�#�� ،�*(b$ز ا��(��ا�<fدة ا��$b)*� و"s#و"� ا���) ، )ت ا�� #vw ان ا��o#�0 ا��u)*�اظb. " #&� ا���) و"s#و"� ا���) �@!��#ت ا��@+�ة، frدة 0 7" �8?a�" 5 �*#ت" ��c �5ظ@" l�nx��53cr2o3 وmwcnts . ز*#دة "5 �ىmwcnts /+ا�� =�2#3�) �@+% و*) z� 0% ا�� )ا:/ ا��#&�ي #b8!=" �*�&##ر-�ن ا���ا� /�-#&) lc#? وا� [-#n 0% ا�� )ا:/ ا��#&�يا(") ا�6ي ، ا�; ز*#دة ا� l � 7 ان ز*#دة "5 �ى . ادى ا�; ا��< %0cr2o3 %0 ���m ا�$o� ا� \�s5 � ���#c ��x��53 " #&� ا���) �@� )ا:+#ت . ا�� )ا:/ ا��#&�ي ادي ا�; ز*#دة 3��ن ط�ر ا��5@�ل ا�$#"� ا�6ي ا> #ج ا�; در�#ت 3@+ .ا��#&�*� "= ز*#دة "5 �ى ا&#-�/ ا��#ر-�ن ا��#&�*� (microsoft word \332\336\355\341 \346\315\323\355\344 \344\314\343125132) al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 14, no. 4, december, (2018) p.p. 125132 effect of al2o3 particles and precipitation hardening on the properties of cast 332 aluminum alloy akeel dhahir subhi* hussein najim abdullah** *,** department of production engineering and metallurgy/ university of technology/ baghdad/ iraq *email: husseinnajim@yahoo.com (received 15 november 2017; accepted 17 may 2018) https://doi.org/10.22153/kej.2018.05.007 abstract in this work, 332 al alloy was prepared and reinforced with (0.5% and 1%) nano-al2o3 particles. the prepared unreinforced and reinforced 332 al alloy with nano-al2o3 were solution heat treated (t6) at 510 ̊c and aged at 225 ̊c with different times (1, 3, and 5 h). hardness test was performed on all the prepared alloys. all prepared alloys were dry slided under different applied loads (5, 10, 15, and 20 n) against steel counterface surface using pin on disk apparatus. the results showed that refinement effect was observed after addition of nano-al2o3 particles and a change in silicon morphology after performing the solution heat treatment. the results also showed that hardness was increased and the wear rate decreased with increasing the nano-al2o3 particles in the matrix of 332 al-alloy. keywords: 332alloy, hardness, nano al203, t6 heat-treatment, wear rate. 1. introduction the distinct combination of properties delivered by al and al-alloys make aluminum one of the most flexible, cost-effective, and striking metallic materials for a wide range of applications from soft, very ductile wrapping foil to the most exigent applications in engineering. they are employed in the automotive industry, aerospace industry, in construction of machines and many other applications [1]. the most important reason for alloying is to increase strength, hardness, and resistance to wear and other mechanical properties. the most common alloying elements in al-si alloys that provide increased strength particularly when combined with heat treatment, are copper, magnesium, manganese, silicon, and zinc. the solid solubility of these elements in aluminum is significant, and in all cases the solubility increases with increasing temperature [1, 2]. aluminum piston alloys are an important group of industrial aluminum alloys that have good mechanical properties at raised temperatures. at the same time, these alloys are resistant to sudden changes in temperature [3]. many aluminum alloys, reinforced with ceramic particles have been investigated extensively. several researchers showed that the presence of ceramic reinforcing particles in the aluminum alloy matrix help with improving its strength. there was also a notable improvement in the resistance for wear with increase of addition of ceramic particles especially when combining with heat treatment [4 6]."s. shivkumar et al. (1990) [7] studied the1effect of solution heat treatment parameters on tensile properties of cast 356.2 aluminum1alloys. they found that increasing1the solution1treatment temperature1has an advantageous effect1on the mechanical properties attainable after heat1treatment. while m. kok (2005) [8] fabricated the 2024 al alloy and reinforced it with al2o3 particles by stir casting technique and studied its mechanical properties. they found that the bonding between al alloy and al2o3 particles and the wettability were improved. akeel dhahir subhi al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 125132 (2018) 126 m. kok and k. ozdin (2006) [9] investigated the effect1of al2o31particle content1on the1wear rate1of 2024 al alloy". "they found that1the wear1rate of1the reinforced1 2024 alloy was significantly less than1that of1the unreinforced 2024 alloy1, and1decreased with1increasing al2o31particles 1content". f. zainon et al. (2016) [10] studied the effects of heat treatment on1the hardness, microstructure1and wear1of1al-alloy 332. they found that the hardness of the alloy has improved and the wear rate was decreased compared to the as-cast alloy. in this work, the effect of al2o3 nano-particles with two different percentages and precipitation hardening with different aging times on the microstructure, hardness, and wear properties were studied. 2. experimental procedure master alloys of (al-cu, al-mg, al-zn, and pure al) brought from the local market and (al 12%si) provided by the general company for electrical industries in baghdad were used as a starting materials to prepare the reference alloy (332). the stirring process was carried out by inserting the stirrer into the crucible while it is inside the furnace. the stirring continued for 5 minutes, in which the crucible was left inside furnace to preserve the solubility. the molten alloy was also stirred just before pouring into the mold cavity. the chemical compositions of the produced castings are shown in table (1). some of the prepared castings are illustrated in figure (1). table 1, chemical composition analysis of produced castings. fig. 1. some of the prepared alloys (as-cast 332 al alloys). after completing the casting process, the aluminum alloys were set for heat treatment. a carbolite furnace is first calibrated using a thermocouple (type k). the first step in heat treatment (t6) is solution heat treatment which is performed at temperature of (510 ºc) in which the alloys are kept in furnace for 5 hours. the second step is quenching the alloys with rapid cooling to room temperature by inserting the alloys in water. finally, the alloys were aged at a temperature of (225 ºc) with three different periods (1, 3, and 5 hours). the alloys, after that, were let to cool down to room temperature in air. the wear test was accomplished in laboratory at the materials engineering department/ university of technology using pin on disk apparatus according to the astm g99-95 standard. the pin on disk apparatus is composed of a rotating disk (277.4 r.p.m) and a specimen holder connected to a lever at one end and the other to hold the weights. the radius of the sliding track (from the center of the specimen to the center of the disk) is (6 cm) the test is done at loads of (5, 10, 15, 20n) and sliding time of 20 min. 3. results and discussion figure (2) shows the microstructure of the as cast alloys with different percentages of nanoal2o3 particles (0%, 0.5%, 1%). it is clear that αal phase dendrites (light gray), eutectic phase (mixture of α-matrix, and fine dark gray si phases) and some intermetallic phases are presented in the matrix. the micrographs showed that the α-al dendrite size of the reinforced alloy with (0.5% and 1% al2o3) (figure 2b and c) is smaller than the unreinforced alloy (figure 2a) in which αal dendrite size decrease with increasing content of nano-al2o3 particles. the reason can be related to the nano-al2o3 particles act as nucleation sites. the effect of stirring process is reflected in the element si % fe % cu % mn % mg % cr % zn % ti % pb % al % 332 alloy 9.02 0.7 2.49 0.2 0.9 0.01 0.4 0.02 0.03 bal. 332 alloy + 0.5% al2o3 9.17 0.71 2.12 0.2 0.82 0.01 0.54 0.02 0.03 bal. 332 alloy + 1% al2o3 9.61 0.65 2.67 0.19 1.57 0.01 0.64 0.02 0.03 bal. akeel dhahir subhi al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 125132 (2018) 127 uniformity of the particle distribution. in stir casting an almost uniform distribution of nanoal2o3 particles can be achieved. in addition to homogenous distribution, with increasing of percentage of nano-al2o3 particles the microstructure was refined and the hardness of 332 al alloy is increased. fig. 2. microstructure of prepared alloys (a) 332 al alloy (b) 332 al alloy with 0.5% al2o3 (c) 332 al alloy with 1% al2o3. the microstructure of solution heat treated 332 al alloys reinforced with different nano-al2o3 percentages is shown in figure (3 a, b, and c). the effect of solution treatment on morphology of eutectic si is evident in figure (3). this change in morphology of eutectic si observed after heat treatments for holding time of 5 hours. eutectic si without heat treatment is evolved in needle-like form as showed in figure (2). after solution treatment we noted that the platelets were fragmentized into smaller platelets with spherical edges, see figure (3). the smaller si particles were changed to rounded shape. the spheroidized morphology of the silicon phase is expected to improve the mechanical properties of the al-si alloys and make them stronger. figure (3) also shows that solution heat treatment has great influence on spheroidization of eutectic silicon particles for the reinforced 332 al alloys with nano-al2o3 particles than that of the unreinforced 332 al alloy figure (3 b and c). it is not only decrease the size of eutectic silicon particles, but also enhances greatly the spheroidization degree of eutectic silicon particles for the reinforced 332 al alloys akeel dhahir subhi al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 125132 (2018) 128 fig. 3. microstructure of solution heat treated 332 al alloys (a) 332 al alloy (b) 332 al alloy with 0.5% al2o3 (c) 332 al alloy with 1% al2o3. figure (4 a, b, and c) illustrates the microstructure of the unreinforced 332 al alloys, 0.5% al2o3, and 1% al2o3 reinforced al alloys respectively. there are two possible combinations of precipitates in these alloys. precipitation of (mg2si) and (cual2), or alternatively (al5mg8si6cu2) and (cual2), where the phase (cual2) forms if the cu concentration is high enough. these precipitates are assumed to be unshearable and their contribution to strength is modelled via looping mechanism of ashby and orowan [11]. strengthening is obtained due to formation of dislocation loops around the precipitates that have attained a critical size, and therefore can no longer be sheared by gliding dislocation. precipitation hardening of the 332 alloys after aging occurs in the matrix saturated with si, cu, and mg in solid solution. the hardening mechanism suggests the formation of gp zones in the early stage of aging, and this is followed by the precipitation of θ″ and θ′. at long aging time, overaging occurs and the hardness drops due to extensive aging when the precipitation turns the equilibrium phase θ. the hardness drop is due to long mean free path between the θ precipitates. the coarsening of the precipitates and the reduced density at longer aging times, widen the inter-particle spacing and facilitate the dislocation motion through the metal matrix. akeel dhahir subhi al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 125132 (2018) 129 fig. 4. microstructure of aged 332 al alloys at time of (3hrs) (a) unreinforced 332 al alloy (b) 332 al alloy with 0.5% al2o3 (c) 332 al alloy with 1% al2o3. figure (5) shows the relationship between hardness and weight percentage of nano-al2o3 particles for the as-cast 332 al alloys. it is clear from this figure that the incorporation of nanoal2o3 particles in aluminum matrix causes reasonable increase in hardness. this increase in hardness value is due to grain refinement of almatrix, and the role of uniform distribution of nano-particles as obstacles to the dislocations motion according to orowan mechanism [12]. the increased hardness can be attributed also to the contribution of metallurgical composition. the hardness is also increased with increasing the percentage of nano-al2o3 particles. the higher hardness (in as cast state) is obtained for the 332 al alloy with 1wt% al2o3 as can be seen in figure (5). the results of hardness test showed that the solution heat treatment and aging increased the hardness value as shown in figures (5), and (6). the higher hardness value was obtained at the aging time of 3 hrs. for the unreinforced and reinforced alloys. it is also observed that with an aging time of 5 hrs. overaging is achieved. this lead to decrease the hardness as compared with that at 3 hrs. fig. 5. the hardness of as-cast and solution heat treated 332 al alloys at different weight percentages of nano-al2o3 particles. akeel dhahir subhi al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 125132 (2018) 130 fig. 6. the hardness of 332 al alloys at different ageing times. the wear behavior of the as cast 332 aluminum alloys has been studied before and after the addition of the reinforcing nano-al2o3 particles. also the study included the alloys after performing solution heat treatment and aging. the pin on disk method was employed for all the specimens cut from alloys at different states (as cast and aged alloys) taking into account the effect of applied load on wear rate . the as cast 332 al alloys before and after reinforcement material addition (nano-al2o3 particles) were studied through plotting the relationship between load and wear rate as in figure (7). it is obvious that the wear rate of the as cast 332 al alloys increases with the increase in applied load. it is clear from the figure that the wear rate initially increases slowly with increase in applied load irrespective of the as-cast 332 al alloy type and at a later stage beyond certain applied load, the wear rate rises up. the load at which wear rate increases suddenly is termed as transition load which in most of the alloys tested was (15n). figure (7) shows that the addition of nano-al2o3 particles led to an improvement in wear resistance of 332 al alloy. in the 332 al alloys reinforced with nano-al2o3 particles, material removal is delayed because the distribution of nano-al2o3 particles in the 332 al alloys during dry sliding. the hard al2o3 particles effectively resist the micro cutting action of counterface asperities and resist also the applied load. it is clear that al2o3 particles have considerably increased the hardness of the 332 matrix alloy. the decrease in the wear rate is related to the hardening effect of al2o3 nano particles in the as cast condition, and due to both al2o3 nanoparticles and precipitation hardening effects in solution heat treated and aged condition. fig. 7. the effect of applied load on the wear rate at sliding time of 20 min as-cast 332 al alloys. this enhancement in wear properties results1can be ascribed to1the improvement of alloy hardness due to the reinforcing particle addition (nano-al2o3), precipitation hardening and may be related to spheroidization of silicon particles as a result of solution heat treatment. the lowest wear rate of the alloys observed was for 332 al alloy with 1% al2o3 nano particles in both states, as cast and precipitation hardened, see figure (8). fig. 8. the effect of load on the wear rate of aged 332 al alloy with 1% al2o3 nano particles with different times at sliding time of 20 min. 4. conclusions 1. the addition of nano-al2o3 particles affect the α-al phase size which has been decreased with increasing the percentage of the nano-particles. 2. nano-al2o3 particles addition increased the hardness of 332 al alloy in which the hardness increases with increasing the nano-al2o3 particles content. this is related to the nanoakeel dhahir subhi al-khwarizmi engineering journal, vol. 14, no. 4, p.p. 125132 (2018) 131 particles that act as barriers to dislocations motion. the results showed that the hardness increased with al2o3 additions, it reached to (92 kg/mm2) when adding 1 wt.% al2o3, but after reinforcing and aging for 3 hrs. the hardness reached to (120 kg/mm2). 3. the nano-al2o3 particles addition resulted in decreasing the wear rate of the 332 al alloys as the addition increases. 4. the solution heat treatment and aging has a significant effect on the eutectic silicon morphology in which the shape changed after solution heat treatment from large platelets into small platelets with rounded edges. this change in silicon morphology improved the hardness and wear resistance. 5. delamination is found to be the dominant wear mechanism in all 332 al alloys tested during dry sliding test. 5. references [1] j.r. davis, asm specially handbook: "aluminum and aluminum alloys", asm international materials park, ohio, (1993). [2] asm handbook, vol. 2 " properties and selection: nonferrous alloys and specialpurpose materials." materials park, ohio (1990). [3] e.r. wang, x.d. hui, g.l. chen. "eutectic al– si–cu–fe–mn alloys with enhanced mechanical properties at room and elevated temperature." materials & design 32, (2011): 4333-4340. [4] m.c shankar, p.k jayashree, r. shettya, a. kinia and s.s sharma. "individual and combined effect of reinforcements on stir cast aluminium metal matrix composites-a review." international journal of current engineering and technology 3, no. 3 (2013): 922-934. [5] a. necat, and a. coban. "the tensile behavior and microstructure of al2o3/sicp reinforced aluminum-based mmcs produced by stir casting method." international journal of science and advanced technology 2, no. 5 (2012): 78-86p. [6] krishnan, b. p., n. raman, k. narayanaswamy, and p. k. rohatgi. "performance of an al-sigraphite particle composite piston in a diesel engine." wear 60, no. 1 (1980): 205-215. [7] s. shivkumar, s. ricci, c. keller, and d. apelian. "effect of solution treatment parameters on tensile properties of cast aluminum alloys." journal of heat treating 8, no. 1 (1990): 63-70. [8] m. kok, "production and mechanical properties of al 2 o 3 particle-reinforced 2024 aluminium alloy composites." journal of materials processing technology 161, no. 3 (2005): 381387. [9] m. kök, and k. özdin. "wear resistance of aluminium alloy and its composites reinforced by al2o3 particles." journal of materials processing technology 183, no. 2 (2007): 301-309. [10] z. fizam, k. r. ahmad, and r. daud. "effect of heat treatment on microstructure, hardness and wear of aluminum alloy 332." in applied mechanics and materials, vol. 786, pp. 18-22. trans tech publications, 2015. [11] salleh, m. s., m. z. omar, j. syarif, and m. n. mohammed. "thermodynamic calculations of aluminium alloys for semi-solid processing." in 7th international conference on mathematics, simulation, modelling, cambridge, ma, united states. 2013. [12] s. yu, p. shao-ping, l. xue-ran, y. zi-run, s. guo-xiong "nucleation and growth of eutectic cell in hypoeutectic al− si alloy-tnmsc." the chinese journal of nonferrous metals 21, (2011): 2186-2191. )2018( 125-132، صفحة 4د، العد14دجلة الخوارزمي الهندسية المجلم عقيل ظاهر صبحي 132 ٣٣٢وعملية التصليد بالترسيب على خواص سبيكة االلمينيوم 3o2alتأثير دقائق حسين نجم عبدهللا** عقيل ظاهر صبحي* العراق /بغداد /الجامعة التكنولوجية /قسم هندسة االنتاج والمعادن **،* husseinnajim@yahoo.com *البريد االلكتروني: الخالصة ). تم %١و %٠٫٥وبنسب مختلفة ( )nm 50(بحجم )3o2al(، مقواة بدقائق أوكسيد االلمينيوم النانوية 332تحضير سبيكة ألمينيوم في هذا البحث تم المقواة وغير المقواة بدقائق أوكسيد األلمينيوم ٣٣٢لجميع سبائك األلمينيوم (solution heat treatment-t6)إجراء عملية المعاملة الحراية المحلولية ٥، ٣، ١وعند ثالث فترات زمنية مختلفة ( )c˚ 225(وكذلك تم إجراء عملية التعتيق عند درجة حرارة )c˚ 510()، عند درجة حرارة 3o2alالنانوية ( نظام المسمار على القرص يطة جهاز البلى اإلنزالقي ذسا. تم اختبار جميع السبائك المحضرة بوساعة). تم إجراء فحص الصالدة لجميع السبائك المحضرة (pin on disk) ) نيوتن). 20، 15، 10، 5لدراسة سلوك البلى الجاف لسبائك األلمينيوم المحضرة وذلك على قرص من الفوالذ المصلد تحت أحمال مختلفة النانوية وكذلك حدوث تغير في شكل طور السيليكون بعد إجراء عملية المعاملة الحرارية )3o2al(عد إضافة دقائق لوحظ حدوث تنعيم في الحجم الحبيبي ب في ارضية )3o2al (. كما أوضحت النتائج زيادة الصالدة و انخفاض معدل البلى مع زيادة نسبة إضافة دقائق)solution heat treatment(المحلولية .٣٣٢السبيكة <4d6963726f736f667420576f7264202d20cdd3ede420c7e1dae1dfc7e6ed20e6c7d3ede120e6dac8c7d339312d203938> al-khwarizmi engineering journal al-khwarizmi engineering journal,vol. 13, no. 3, p.p. 9198 (2017) influence of nanoreinforced particles (al2o3) on fatigue life and strength of aluminium based metal matrix composite alalkawi hussain j. m.* aseel a. hamdany** abbas ahmed alasadi*** *,**department of electromechanical engineering/ university of technology ** department of mechanical engineering/ university of al-mustansiriyah *email: alalkawi2012@yahoo.com **email: aseelbaky@yahoo.com ***email: dr.abbas_alasadi@yahoo.com (received 5 december 2016; accepted 28 march 2017) https://doi.org/10.22153/kej.2017.03.005 abstract in this investigation, al2o3 nano material of 50nm particles size were added to the 6061 al aluminium alloy by using the stir casting technique to fabricate the nanocomposite of 10wt% al2o3. the experimental results observed that the addition of 10wt% al2o3 improved the fatigue life and strength of constant and cumulative fatigue. comparison between the s-n curves behaviour of metal matrix (aa6061) and the nanocomposite 10wt% al2o3 has been made. the comparison revealed that 12.8% enhancement in fatigue strength at 107cycles due to 10wt% nano reinforcement. also cumulative fatigue life of 10wt% nanocomposite was found to be increased by 33.37% and 39.58% for low-high and high-low loading sequences, respectively, compared to the metal-matrix cumulative life. keywords: al2o3 nanoparticles, aa6061/10wt%, constant and cumulative fatigue, mmcs. 1. introduction fatigue life and strength are the most important parameters in which the stress failure occurs less than the allowable stresses because of combined loading; prediction of its value can avoid catastrophic in machines at the service [1]. metal matrix composites have been studied and are widely used in an industry for several applications in aerospace, automotive and others [2-5]. estimating fatigue life is an important parameter to design equipment with safety. a full fatigue fracture behaviour have been studied for al-sic nano-metal composite mmcs with 50 nm particles size, different vol.% up to 6 nanocomposites have been fabricated to find optimum fatigue behaviour, it was examined the internal fracture surface of the same nano-metal composite, a ductile-brittle fracture with an increase in the ductile fracture at higher nanoparticles within higher fractions [2]. the fatigue behaviour of aluminium (aa2014) alloy reinforced with micro and nano-sized alumina particles al2o3 have studied for their structural applications. microscope examinations by high resolution (tem) images were used to evaluate the fatigue behaviour of the composite samples. it was found improving in the mechanical and fatigue properties by the nanoalumina reinforced al-composites. compared to the micron sized alumina reinforced composites. the failure cycle was observed to be higher for the nano alumina reinforced composites in comparison with micron sized alumina composites due to a lower order of induced plastic strain [3]. fatigue parameters have studied on al reinforced with (sic) particulates. comparison have mode based on the matrix aluminium alloy alalkawi hussain j. m. al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 9198(2017) 92 containing si. the different weight percentages of sic particulates in the size range of some different µm were used. fatigue tests indicated that the nanocomposite fatigue resistance increased with increasing content of sic particulates. sic particulates improved fatigue resistance which acting as barriers to cracks deflecting the growth plane of cracks resulting in decreased crack propagation rates [4]. experimental work carried out to find the fatigue properties of al-matrix nanocomposites using friction stir processing technique (fsp). aluminium alloy (aa5052) with different amounts of nanoparticles up to 6 stages were fabricated to get homogenous dispersion of nanoparticles inclusions. microstructural studies of high resolution techniques showed that nanometric al3ti with different nano-particles in size were scattered throughout a fine-grained al matrix (<2 µm) an improvement in the tensile strength and hardness was attained. uniaxial stress-controlled tension– tension fatigue testing (r = 0.1) were applied to estimate the fatigue characterization of the nanocomposites alloy. the results were compared with the un-processed (annealed) and fsped alloy without pre-placing tio2 particles. it was found that fsp of the aluminum alloy increased the fatigue strength (at 107 cycles) for about 28% and 32% compared with the annealed specimen when the concentration of the reinforcing particles was 2 and 3.5 vol. %, respectively [5]. the aim of the present work is to investigate the fatigue properties (life and strength) under interaction of nanomaterial as reinforcement with the aa 6061 al alloy as metal-matrix. 10wt% al2o3 nanoparticles were added to al 6061 metalmatrix for manufactured the nanocomposite and tested under fatigue condition to determine the life and strength of nanocomposite. 2. experimental work this section focuses on the materials used and its chemical composition, mechanical properties in addition of nanocomposite manufacturing and the tensile testing. 2.1. selection of materials the matrix metal used for the present work is 6061 al alloy. it is widely used the alloy easy to manufacture, preparation and available. table (1) gives the chemical composition in wt% of the matrix used. table 1, chemical analysis of 6061 al. alloy examined at state company for inspection and engineering (sier) wt. % in comparison with ref [6]. elements wt.% cr zn co si ti mn mg fe others al standard [6] 0.040.35 max 0.25 0.150.4 0.4-0.8 max0.1 5 0.8-1.2 max 0.15 max 0.7 0.05 balance experimental according to sier 0.18 0.13 0.28 0.61 0.08 0.96 0.11 0.54 balance the mechanical properties of 6061 al. alloy compared with ref [6] are summarized in table (2). table 2, mechanical properties of 6061 al. alloy tested at sier compared with the findings of ref [6]. 6061 al properties hardness hb strength σσσσu (mpa) yield stress σσσσy (mpa) modules of elasticity (gpa) ref.[6] 30 149.76 138.06 70-80 experimental sier 32 154 140 74 2.2. the reinforced material hard particles like al2o3 are usually used as reinforced material in the (mmcs) metal-matrix composites (mmcs).the above particle is commonly used with aluminium as reinforcement and the application of the al2o3/al composites in the aircraft industries, automotive where the tribological characterization is very important [7]. alalkawi hussain j. m. al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 9198(2017) 93 for present work the adopted reinforced material used in manufacturing the nanocomposite is al2o3 with the particle size of 50nm. the chemical analysis of the reinforced material can be shown in table (3). table 3, chemical analysis of al2o3 wt%.[8]. element cao tio2 fe2o3 others alumina wt.% 1.1 1.8 0.8 0.02 97 2.3. composites preparation the stir casting method used for preparation the 6061al/al2o3 composites. the reinforced particles were preheated to 200°c before putting into the melt. the stirrer speed of 450 rpm and the casting temperature was 850°c. more details of the test rig which used to prepare the nanocomposite can be seen elsewhere [9]. thus, the nanocomposite of 10%al2o3 was obtained in the form of rod of diameter 12 mm and length of about 100mm. the reason of selection 10wt% al2o3 based on the findings of ref [10] who found that the maximum improvement in mechanical properties was occurred at 10wt% al2o3 reinforcement. 2.4. fatigue specimen geometry the material was received from the casting moulds as 12 mm in diameter and 100mm length. 12 specimens with nano and 12 specimens as received were manufactured using programmable cnc lathing machine by writing a suitable programme. then all specimens were machined. careful attention was done to produce good surface finish and to reduce the tensile residual stresses. the surface of all specimens were polished using 260, 300, 400, 600, 800, and 1000 silicon carbide papers and after that three different diamond laps, course 3/2 micron, fine 1 micron and finally extra-fine 1/4 micron. the last stage was cleaning by distilled water then washing the specimens for polishing with alcohol. the specimens were numbered and tested for measuring the roughness of selected specimens. table 4, selective surface roughness results of 8 specimens. specimens no 1 3 5 7 9 11 13 15 ra µm 0.4 0.28 0.5 0.44 0.6 0.66 0.36 0.49 rt µm 1.2 0.9 1.32 1.07 1.4 1.44 0.96 1.02 the fatigue test specimen can be illustrated in fig. (1). fig. 1. the specimen dimensions in mm according to (din 50113) standard values. 2.5. fatigue test machine a rotating bending machine fatigue–testing schenck product type was used to implement all fatigue tests, with constant and variable amplitude. the fatigue specimen which is shown in fig. (1) has a round cross section and is subjected to an applied load form the right side of the perpendicular to the axis of specimen, developing a bending moment. therefore the surface of the specimen is under tension and compression stress when it rotates. the value of the load (p) is measured by newton (n), applied to the specimen for a known value of stress (σ) measured by (n/mm2) and used from applying the relation below: ������ = 32 × 125.7 × ���� � × �� where d (mm) is the minimum diameter of the specimen, and force arm is equal to 125.7mm, and [11]. the fatigue test rig is shown in fig (2). alalkawi hussain j. m. al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 9198(2017) 94 fig. 2. fatigue bending machine test. 3. results and discussions 3.1. constant fatigue results the specimens were tested under constant amplitude fatigue, stress at room temperature (rt), to estimate the s-n curves .the results of this series are illustrated in table (5) and figure (3). table 5, s-n curve results of al6061 and al6061/10 wt. % nanocomposite. al6061 metal-matrix al6061-10 wt% nanocomposite specimen no. applied stress(mpa) nf cycles specimen no. applied stress(mpa) nf cycles 1 2 3 140 6500 12000 8000 16 17 18 140 8800 11000 12500 4 5 6 120 18600 22600 25000 19 20 21 120 24600 30000 26000 7 8 9 100 43200 48000 40000 22 23 24 100 72000 66000 74200 10 11 12 80 118000 135000 127000 25 26 27 80 205000 217600 225000 13 14 15 60 380000 405600 422000 28 29 30 60 510000 525000 49800 fig. 3. s-n curves for both 6061 al and 10wt% nanocomposite. from table (5), the best fit equation which accurately describe the behaviour of the metal and the nanocomposite is the basquin formula which can be written in the form. �� = ��� � …(1) where a, b are material constants. these constants can be obtained by the equations � = � ∑ ��� ����� !��"∑ �� ��� ∑ �� !�� # �$ # �$% # �$% � ∑ &�� !��' ( ")∑ �� !�� # �$% * (# �$% ...(2) and +,-� = ∑ �� ���"� ∑ �� !�� # �$% # �$% � …(3) where h is the number of test specimens applying the above equations to the experimental data in table (5), the basquin equations with their correlation coefficient (r2) can be seen in table (6). table 6, basquin equations with correlation factor for metal and composite. 6061 al alloy 6061 al /10wt% nanocomposite improvement factor (if) for fatigue endurance limit �� = 1099�� "0.112 r2=0.9962 �� = 1055�� "0.132 r2 =0.983 12.28% if is calculated from the equation, 45 = �6.7�898:�"�6.7�;<=9>� �6.7�898:� ∗ 100 where �@.a is endurance limit stress (mpa). the �@.a was calculated from the basquin equation at 107 cycles. the results revealed that �@.a�cdef�� = 87.3 mpa and �@.a�hfh�� = 99.53 mpa. if (improvement factor was found to be 12.28% due to nanomaterial addition. many workers focused on the fatigue properties such as akio et.al. [12] and mussert et.al.[13]. they alalkawi hussain j. m. al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 9198(2017) 95 tested nanocomposite under fatigue cycling and they concluded that the nano reinforced work to strengthen the metal matrix and to enhance the fatigue strength of nanocomposites. hafeez and senthil [14] found that the ceramic particles strengthen the metal-matrix composite fatigue properties (fatigue strength), maintaining good ductility at high temperature creep resistance. 3.2. cumulative fatigue results cumulative fatigue tests were carried out at the same conditions for s-n curve i-e room temperature (rt) and stress ratio (r=-1). table (7) gives the experimental results obtained for materials, metal-matrix and nanocomposite (mmcs). table 7, cumulative fatigue results for metal-matrix and nanocomposite (mmcs). specim en no loading sequences (mpa) metalmatrix 6061 al nanocomposite 6061 al/10wt% al2o3 loading programme 31 32 33 80-120 34600 38000 44000 51000 60000 64000 34 35 35 120-80 30000 31000 26000 42000 48000 54000 the improvement in cumulative fatigue lives due to 10wt% nanomaterial al2o3 can be illustrated in table (8). table 8, shows the improvement factor in cumulative fatigue live due to 10wt% al2o3. loading sequences (mpa) nf average metal-matrix nf average nanocomposite if 80-120 38867 58333 33.37% 120-80 29000 48000 39.58% the results of table (8) are plotted in fig. (4). fig (4) shows the enhancement of cumulative fatigue lifes. fig. 4. improvement of cumulative fatigue life due to 10wt% al2o3. the applications of nanocomposites based on aluminium alloy as a metal-matrix and al2o3 nano-reinforced material are commonly used in aircraft industries, space applications and automotive where the fatigue and tribological properties are required [15]. comparison has been made between the mmcs and metal matrix and the comparison revealed that the mmcs have better fatigue resistance [16]. it is observed from the constant and cumulative fatigue testing; tables (5), (7) that the nanocomposite of 10wt% al2o3 achieved higher fatigue strength and life. the reasons may be the followings: 1. uniform dispersion of al2o3 particles in the nanocomposite [17]. 2. less porosity and homogeneous dispersion of al2o3 which in turn increased the mechanical alalkawi hussain j. m. al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 9198(2017) 96 and fatigue properties .porosity should be kept to minimum level [18]. 3. al2o3 addition increases brittleness in which the mechanical and fatigue properties increased [19]. 4. the fine size of the particles leads to improve the mechanical and fatigue properties. 5. good thermal bounding between the 6061 al. alloy and the reinforced material the attribute to enhance fatigue behaviour [2]. 6. the high mechanical properties of al2o3 itself leads to enhance the fatigue strength and life [6]. 4. conclusions a fundamental understanding of the mechanism which provides the enhancement in fatigue properties is required and the following remarks derived from this work are concluded. 1. the fatigue strength of 10wt% al2o3 nanocomposite at 107cycles was improved by 12.28% compared to as cast al 6061 alloy. 2. the cumulative fatigue lives of the 10wt% al2o3 nanocomposite were enhanced by 33.37% for low-high loading and 39.58% for high-low loading 3. the above improvements of the nanocomposite may be due to uniform distribution, less porosity , high bounding between al2o3 and 6061 al. alloy, high dislocation density, high mechanical properties of al2o3 itself. acknowledgments the authors are grateful to the university of technology/department of electromechanical engineering for the provision of laboratory facilities. 5. references [1] h. k. d. h. bhadeshia, "steels for bearings", progress in materials science, 57: 268-435, 2012. [2] h. g. yazdabadi, a. ekrami, h.s. kim, and a. simchi," an investigation on the fatigue fracture of p/m al-sic nanocomposites meatallurgical" materials transactios a, vol. 44a, 2013. [3] r. senthilkumar, n. arunkumar, m. m. hussian,"a comparative study on low cycle fatigue behaviour of nano and micro al2o3 reinforced aa2014 particulate hybrid composites", results in physics, vol. 5, 273– 280, 2015. [4] c. kaynak, s. boylu,"effect of sic particulates on the fatigue behaviour of an aialloymatrix composite", materials and design, vol.27, 2006. [5] p. s. zangabad, f. khodabakhshi, a. simchi , a.h. kokabi,"fatigue fracture of friction-stir processed al–al3ti–mgo hybrid nanocomposites", international journal of fatigue, vol.87 ,266–278, 2016. [6] v. bharath, n mahadev., v. auradi, "preparation characterization and mechanical properties of al2o3 reinforced 6061 al particular mmcs", international journal of eng. research and technology (ijert) vol.1 issue 6, 2012. [7] a. mazahery, h. abdizadeh, hr baharandi, "development of high-performance a356/nanoal2o3 composites", materi. sci. eng. 518, 61-64, 2009. [8] o. s.mohsen, a. mazhery,"aluminium-matrix nanocomposites swarm intelligence optimization of the microstructure and mechanical properties", materials and technology 46, 6,613, 2012. [9] h.j.m alalkawi., a. a. alrasiaq, m. a. a. al jaafari," performance study on mechanical properties in 7075 aluminium alloy and al2o3 nanocomposite" journal of eng, and tech., accepted for publication 2017. [10] h.j.m alalkawi, h. a. alsalihi,”an investigation of some mechanical properties of 6061 a alloy /10 wt% al2o3 nanocomposite". [11] n. m abdulmuhssan., a. h, hamed. and h. j.,m. al-alkawi, "effect of temperature on fatigue transition life and strength of aluminium alloy", engineering and technology journal, vol.30, n0.6, 2012. [12] k. akio, o. atsushi, k. toshiro, t. hiroyuki, “fabrication process of metal produced by vortex method", j. japan inst. light met., 49, pp. 149–154, 1999. [13] k. m. mussert , w. p. vellinga, a. bakker s. van, d. zwaag, "a nano-indentation study on the mechanical behaviour of the matrix material in an aa6061 al2o3 mmc",j. mater. sci., 37, issue 4, pp.78-794, 2002. [14] h. ahamed , v. s. kumar," role of nanosize reinforcements", j. of. alloys and compounds, 505, pp 772-782, 2010. alalkawi hussain j. m. al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 9198(2017) 97 [15] a. mazaherg, h. abdizadeh ,h.r.baharrandi, "development of high performance a356/nano al2o3 composites", materials science and engineering, a 518, 61–64, 2009. [16] r.h. jones, c.a. lavender, m. t. smith ," yield strength-fracture toughness relationships in metal matrix composites ", scripta metallurgica, 21,issu 11, 15651570,1987. [17] m. singla, d.d. dwivedi, l. singh, v. chawla ,"development of aluminium based silicon carbide particulate metal matrix composite", j.of minerals and materials characterization and engineering , vol.8, no.6, pp 455-467, 2009. [18] r. k. bhushan, s. kumar, s. das, "fabrication and characterization of 7075 al. alloy reinforced with sicparticulaters", intern. j. of advanced manufacturing technology 65, 611-624, 2013. [19] a. singh, l. kumar, m. chaudhary, o. narayan, p. sharma, p.singh, b c.kandpal, s. ashotosh,"manufacturing of ammcs using stir casting process and testing its mechanical properties ", int. j. adv. eng. tech 26-29, 20 )2017( 91-98، صفحة 3د، العد13دجلة الخوارزمي الهندسية المجلم حسين جاسم العلكاوي 98 االساس ي) على عمر ومقاومة الكالل لمركب ذ3o2alتاتير حبيبات المادة النانوية المقواة ( المعدني **الباقي الحمداني اسيل عبد العلكاوي* حسين جاسم محمد ***عباس احمد االسدي الجامعة التكنولوجية *،**قسم هندسة الكهروميكانيك/ قسم الهندسة الميكانيكية/ الجامعة المستنصرية * alalkawi2012@yahoo.com*البريد االلكتروني: aseelbaky@yahoo.com**البريد االلكتروني: dr.abbas_alasadi@yahoo.com***البريد االلكتروني: الخالصة باستخدام تقنية السباكة بالتحريك لتصنيع aa6061 نانوميتر الى سبيكة االلمنيوم 50ذات حجم حبيبات 3o2alفي هذا البحث تم اضافة المادة النانوية وزنية حسنت من عمر بوصفه نسبة %3o2al 10wt.النتائج المستخرجة عمليا اوضحت ان اضافة 3o2alمن المادة النانوية %10wtالمركب النانوي ذو .واوضحت المقارنة %3o2al 10wtوالمركب النانوي aa6061للمعدن االساس n-sمقاومة الكالل الثابت والمتراكم .تمت مقارنة بين سلوك منحنيات و% %33.37اكمي ازداد نسبة للمادة المقواة. كذلك وجد ايضا ان عمر الكالل التر %10wدورة نتيجة 710في مقاومة الكالل عند %12.8تحسن بمقدار .واطئ على التوالي مقارنة مع العمر التراكمي للمعدن االساس-ومن عالٍ عالٍ -للتحميل المتتابع من واطئ 39.58 <4d6963726f736f667420576f7264202d20312d3130c7cde3cf20e4c7eddd20e6dae3c7d1> al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 15, no. 4, december, (2019) p. p. 19 effect of laser shock peening on the fatigue behavior and mechanical properties of composite materials ahmed n. al-khazraji* ammar a. mutasher** *, **department of mechanical engineering/ university of technology *e-mail: dr_ahmed53@yahoo.com **e-mail: ammar1199011@gmail.com (received 28 april 2019; accepted 25 august 2019) https://doi.org/10.22153/kej.2019.08.004 abstract in this study, laser shock peening (lsp) effect on the polymeric composite materials has been investigated experimentally. polymeric composite materials are widely used because they are easy to fabricate and have many attractive features. unsaturated polyester resin as a matrix was selected and aluminum powder with micro particles as a reinforcement material was used with different volume fraction (2.5%, 5% and 7.5%). hand lay-up process was used for preparation the composites. fatigue test with constant amplitude with stress ratio (r =-1) was carried out before and after lsp process with two levels of energy (1joule and 2joule). the result showed an increase in the endurance strength of 25.448% at 7.5% volume fraction when peened is 1j laser energy. also, the ultimate strength and young’s modulus were increased by 6.474% and 10.588% respectively after lsp with the same laser energy. on the other hand, composites with (2.5% and 5%) volume fraction manifested a reduction in the mechanical and fatigue strength especially when treated by 2j laser energy. keywords: fatigue life, endurance limit, fatigue and mechanical properties, composite materials, laser shock peening, polymer matrix composites. 1. introduction many researches have been prepared to study the composite materials and the enhancement of mechanical and fatigue properties. composite materials are defined as the mixture of two or more constituents, and this is usually done at the microscopic scale without any soluble of one into another [1]. polymers are usually reinforced with particles fillers to have a special mechanical and thermal properties. polymeric composite materials; especially reinforced by fillers have a wide range of applications. these types of composites are used in the manufacturing as abrasive and cutting tools, internal parts of automotive & airplane, and for welding such a plastic welder of the breaking metallic component. this wide range of usage is due to features such as minimum weight, slightly acceptable stiffness and easy to prepare [2]. fatigue is widely defined as the relation between stress applied and number of cycles to fail. this failure is due to the micro cracks in the matrix material from first initiates, propagates and finally leads to failure [3]. lsp is a surface treatment process used to enhance the fatigue strength, metallurgical and mechanical properties of metal by treating and modifying the surface and introducing compressive residual stresses via high energy laser pulse impacting material’s surface [4]. the behavior of peening process is different in composite materials, especially polymeric matrix composite (pmc) since it is basic consist of more than one constituent. each one has roughly higher mechanical and metallurgical properties than the ahmed n. al-khazraji al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 19 (2019) 2 other which causes various effects from point to point and leads to a complicated behavior that is hard to be predicted. aseel jasim mohammed [5] investigated of the laser treatment influence on the fatigue strength composite materials. the composite material that was used consisting of polyester resin as a matrix and reinforced with steel layer and fiber e-glass in the form of laminate composite material with (1mm) thickness and [+45/-45]s and [0/90]s fiber angles. two types of laser were used for this investigated (band and pules). the result observed that the fatigue strength after treatment was increased by about 23%. mahdi n. m. shareef [6] studied the effect of conventional shot peening on the fatigue life and mechanical properties of composite materials. polyester/al powder with volume fractions 2.5%,5% and 7.5% was used. shot peening at three different durations was investigated. the result demonstrated that the mechanical properties of 7.5% al powder were increased with rising shot peening time. also, the fatigue results for 5% al powder composites depicted, the fatigue strength was increased after 2 min shot time. for 7.5% al powder composites, the fatigue strength was improved to maximum level at 4 min shot time. ahmed n. alkhazraji et. al. [7] investigated of the shot peening effect on fatigue and mechanical properties of two types of composite materials. the first material was prepared from unsaturated polyester reinforced with fiber e-glass by 33% volume fraction. the other material was unsaturated polyester with 2.5% volume fraction of al powder. the result was showed an improvement in mechanical and fatigue properties of polyester/fiberglass after shot peening process. on the other hand, the properties of polyester/al powder were reduced after treatment. alexander becker [8] studied the effects of both (lsp) and shot peening (sp) on the fatigue strength using aluminum alloy in two conditions 7075-t6 and 7075-t0. the results displayed increase in the fatigue strength in both lsp and sp process compared with un-peened specimens. lsp doubled the fatigue strength and sp increased the fatigue strength about 1/6 compared to un-peened specimens. also, the lsp exhibited no hardening effect determined, on other hand, the sp process showed a significant hardened area on the surface. abdullahi k. gujba et. al. [9] investigated the effect of lsp on the materials properties by using q-switched laser beam pulses type to study the surface modification and showed that the lsp introduced a compressive residual stress about 4-5 times in depth across the surface of material than conventional sp techniques. also, the enhancement in fatigue and surface properties of steel and aluminum was revealed by dislocation peening effect at the dynamic precipitation. fadhel abbas abdulla et. al. [10] studied the effect of ultraviolet irradiation on the fatigue life of the natural composites, the polyester resin was used as a matrix with egg shell, date nuclei and palms leaf as a reinforcement by using (20%, 40% and 60%) volume fraction. ultraviolet was applied for three different times (100, 300, 500) hours. the result depicted that the increasing time of ultraviolet results in reduction of tensile and endurance stresses. najwa j. jubier et. al. [11] studied the effect of ultraviolet on the fatigue behavior of composite materials, by using epoxy with sio� nanoparticles and different volume fractions (1%,3%,5%,7% and 10%) reinforced with 6 layers of chopped mat e-glass fiber. fatigue behavior was investigated for un-irradiated and ultraviolet irradiated composites for (240 hours) at ambient temperature and stress ratio (r=-1). the results demonstrated the increasing in the fatigue strength after applying of ultraviolet radiation due to the formation of crosslinking structure. according to the literature review, there are little researches have been paid attention to study the effect of surface treatment and lsp effect of polymeric composite materials, and no published research was found which studied lsp effect on particulate composite materials. in this research paper will be investigated the influence of laser peening with water confined layer on mechanical and fatigue properties of polymeric composites reinforced by fillers. 2. experimental work the experimental procedure which was used for this research preparation can be explain briefly as follow: 2.1. preparation of the specimens the materials were prepared in a plate with size (300x280x4) mm according to mahdi [6]. the matrix is unsaturated polyester resin and its properties are listed in table (1). aluminum powder was used as a reinforcement material and it’s a filler with particles size (50-100) µm; table (2) shows the properties of it. hand lay-up technique was used for the fabrication process since it is easy and can be used to produce composites in different forms and sizes. the mold was made from clean glass, coated by petroleum ahmed n. al-khazraji al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 19 (2019) 3 jelly (vaseline) and covered by al foil to avoid the adhesion that happen between the materials and the mold. 1.5% mekp (abbreviation to methyl ethyl ketone peroxide) from the volume of unsaturated polyester was added to the mixture and then al powder was added during the reaction has begun. composite materials were prepared with three different volume fraction of al powder (2.5%, 5% and 7.5%). table 1, the properties of polyester resin [12]. density (ρρρρ)))) (��/� ) elastic modulus e (gpa) poisson ratio (νννν)))) 1211 1.0602 0.38 table 2, the properties of al powder [13]. density (ρρρρ)))) (��/� ) elastic modulus e (gpa) tensile strength �� (mpa) 2700 71 60 2.2. laser shock peening laser shock peening (lsp) process depends on several parameters, such as type of laser source, laser plasma pressure, loading time of laserinduced shock wave, material condition, and plasma confinement layer [14]. the laser plasma pressure can be predicted by the following equation when using water as a confining layer [15]: ������ = 1.02��� ...(1) �� = � � �� ... (2) where (��) is the laser intensity (gw/cm2), (k) energy per pulse of laser beam, (a) spot area and (t) pulse duration. lsp usually done with laser intensity �� reach by about several (gw/cm2) for the plasma pressure being enough for inducing of compressive residual stresses [15,16]. q-switched nd-yag laser pulse was used to generate the shock wave on the surface of the specimen, figure (1(a)). the peening procedure, which was used is to prepare this study, is the same as that followed in metals [17]. the surface was coated at the beginning with a black paint as a protective layer and to increase the efficiency of the energy absorption. also, the specimen was submerged in water at a height about (2-3) mm from the specimen’s surface to work as a confining layer and protect the specimen’s surface from the high thermal energy that may happen, figure (1(c)). lsp was applied on the two upper and lower surfaces. the parameters that used in this research study, are illustrated in table (3), and the selection of these parameter was done to applied laser intensity between (1-5) gw/cm2 according to equation (2). figure (1(b)) shows the distribution of laser peening and the fatigue specimen after being treated by lsp. table 3, the parameter of laser peening. energy (joule) wave length (nm) water height (mm) pulse duration (ns) laser intensity (gw/ cm2) 2 1064 3 7 4.04408 1 1064 3 7 2.02204 fig. 1. (a) q-switched nd-yag laser pulse, (b) fatigue specimen when treated by laser peening and (c) schematic diagram and basic principle of laser peening. ahmed n. al-khazraji al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 19 (2019) 4 2.3. fatigue test the fatigue test was done by using (bending alternating hsm20, as shown in figure (2)), it’s available in the department of mechanical engineering at university of technology/ baghdad. this device is a strain-controlled fatigue and used by applying a constant deflection to end of the cantilever beam. the test was carried out at room temperature with zero mean stress (r= -1) and 25hz frequency. the size and shape of specimens selected according to the machine's manual [18], as shown in figures (3). fig. 2. bendingalternating fatigue device hsm20. fig. 3. fatigue specimen according to the machine's manual [18] (all dimensions are in mm). 2.4. tensile test the test was done to investigate the mechanical properties (ultimate stress and young’s modulus) before and after laser peening. the tensile specimens were cut and prepared according to astm d638 [19], shown in figure (4), then tested and the results were obtained. the test was performed at speed (2 mm/min) by using (tinius olsen (h50kt)) which, is available found in mechanical engineering department/ university of technologybaghdad. fig. 4. tensile specimens according to astm d638 (all dimensions are in mm). 3. results and discussion three samples of composite materials were prepared to study the lsp effect on the mechanical and fatigue properties. the testing was done before and after lsp treatment. 3.1. mechanical properties figures (5, 6, 7 and 8) and tables (4 and 5) manifest tensile results of untreated and lsp treated polyester/al powder composite materials under two levels of laser pulse energy (1j and 2j). figure (5) shows stressstrain diagram for 2.5%, 5% and 7.5% volume fraction of al powder. all the mechanical properties were increased with increasing the volume fraction, this attitude is normal because of the rise of reinforcement material which leads to catch the matrix phase and give more binding, and was proved in many previous researches [6]. after treating by laser, figures (6, 7 and 8) depict the comparison among un-treated stress-strain curve and those after treated by 1j and 2j laser pulse for (2.5%, 5% and 7.5%) volume fraction respectively. from figure (6), it is obvious that all mechanical properties of 2.5% volume fraction were decreased with the increasing laser energy, and this behavior is due to cracks formation at the matrix material due to the high brittleness of polyester at low volume fraction which was weak to endure the shock wave. figure (7) show the stressstrain curves for composite at 5% al, and as clear, when 1j laser energy was used for lsp the mechanical properties slightly not ahmed n. al-khazraji al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 19 (2019) 5 affected, but it decreased with amount approximately smaller than that observed with 2.5% volume fraction after the increasing of laser beam energy to 2j. this is an evidence that the composite material with this volume fraction became more resistance to the peening process. for 7.5% volume fraction as shown in figure (8), the treatment by laser leads to increase the ultimate stress and the modulus of elasticity, and the best case was observed at 1j laser energy. this behavior is due to the thermomechanical process increased the adhesion among the two phases which construct this type of composite, and inducing compressive residual stresses into the matrix materials leads to microstructure change which increased the mechanical properties [9]. fig. 5. tensile results with different volume fractions. fig. 6. tensile results of 2.5% volume fraction with and without treatment. fig. 7. tensile results of 5% volume fraction with and without treatment. fig. 8. tensile results of 7.5% volume fraction with and without treatment. table 4, the mechanical properties of the composites (all values are in mpa). volume fraction (%) ultimate stress young’s modulus 2.5 33. 837 2170 5 35.91 2532 7.5 38.52 2921 ahmed n. al-khazraji al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 19 (2019) 6 table 5, the mechanical properties after treatment by laser. 3.2. fatigue life figure (9) elucidate the sn curves for different volume fractions of al powder composite samples, and it is clear that 7.5% volume fraction have the higher fatigue strength comparing with 2.5% and 5%. this behavior due to as referred above that the increasing of reinforced material leads to more binding of the matrix and increased the fatigue strength [6]. figures (10, 11 and 12) evince the sn curves with different laser energies at (2.5%,5%, and 7.5%) volume fraction, respectively. it is clear that for 2.5% and 5% al powder composites, the increasing of laser beam energy leads to reduces the fatigue strength, and this reduction is due to the cracks that were happened into the matrix materials. the reduction in fatigue strength was clearly less at 5% volume fraction after lsp comparing with 2.5% volume fraction, also the using of 1j laser energy for peening the fatigue strength of composite with 5% al powder slightly not affected. this was an evidence that the increasing in volume fraction gives the composite materials more resistance to the shock wave and crack initiation. composite materials with 7.5% volume fraction exhibited an increase in the fatigue strength with the two values of laser beam energy, and the higher fatigue strength was obtained at 1j and then slightly reduced after using of 2j laser energy. lsp was increased the fatigue life of 7.5% volume fraction, this was mainly due to the thermomechanical process which produced by laser peening that reducing the tensile residual stresses through the surface, which in turn preventing crack initiation leads to increasing of fatigue strength [9]. fig. 9. sn curve of polyester/al powder with different volume fractions. fig. 10. sn curve of polyester with 2.5% volume fraction al powder when peening by laser energy 1j and 2j. treated by 1 j treated by 2j volume fraction (%) ultimate stress (%) young’s modulus (%) ultimate stress (%) young’s modulus (%) 2.5 -7.474 -8.741 -11.002 -16.58 5 -0.556 -1.974 -5.43 -7.071 7.5 6.474 10.588 3.411 5.7925 ahmed n. al-khazraji al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 19 (2019) 7 fig. 11. sn curve of polyester with 5% volume fraction al powder when peening by laser energy 1j and 2j. fig. 12. sn curve of polyester with 7.5% volume fraction al powder when peening by laser energy 1j and 2j. table (6) shows the endurance strength of each type of composites with and without treated by laser which was calculated at 10 cycles by using the following fatigue estimation equation (basquin equation) [3]: ! = " ∗ $% &' … (3) where a and b are constants. the endurance limit of 2.5% and 5% al powder was reduced when treated by laser, and as shown the high reduction was occur at treated the 2.5% volume fraction composite with 2j laser energy, which reduced by about 35.686%. the reduction is slightly less for 5% volume fraction which was reach by about 22.219% at treated by 2j laser. on the other hand, the laser treatment enhanced the fatigue endurance strength at 7.5% volume fraction, which was increased by about 25.448%, and 22.197% when used by 1j and 2j laser energy respectively. figure (13) also demonstrate the effect of laser beam energy and various volume fraction on the endurance strength of polyester/al, it’s clear the resistance to crack formations by laser impact was increased with the increasing of volume fraction. fig. 13. changing in endurance limit with increasing laser energy. table 6, endurance strength before and after peening by laser. 4. conclusions the main points that can be concluded from the achieved results of the present research are: 1. laser peening treatment of polyester/al powder composites with 7.5% volume fraction increased the fatigue endurance strength by about 25% due to inducing of compressive residual stresses. 2. the ultimate stress and young’s modulus of polyester/al powder composites with 7.5% volume fraction were increased by about 6.474% and 10.588% respectively due to compressive residual stresses after treatment by 1j laser peening. 3. laser peening process is not suitable for polyester/al powder composites with 2.5% and 5% volume fractions, because it increases the cracks into the composites. so, it’s not % un-treated (mpa) treated by (1j) treated by (2j) mpa % mpa % 2.5 4.9657 4.0653 -18.133 3.1936 -35.686 5 5.9116 5.8761 -0.6 4.5981 -22.219 7.5 6.2919 7.8931 25.448 7.6886 22.197 ahmed n. al-khazraji al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 19 (2019) 8 recommended to use at these volume fractions of composites. 4. the resistance of polyester/al powder to laser shock wave was increased with the increasing of volume fraction to 7.5%. 5. laser peening with 1j energy accompanied by 7.5% volume fraction was the best state which increased the endurance strength and other mechanical properties. 5. references [1] isaac m. daniel and ori ishai, “engineering mechanics of composite materials,” new york oxford, 1994. [2] ibtihal a. mahmood, wafa a. soud and orhan s. abdullah, “effects of different types of fillers on dry wear characteristics of carbonepoxy composite,” al-khwarizmi engineering journal, vol. 9, no. 2, pp. 85 -93, 2013. [3] yukitaka murakami, “metal fatigue: effects of small defects and nonmetallic inclusions,” elsevierscience ltd, 2002. [4] michael r. hill, adrian t. dewald, jon e. rankin and matthew j. lee, “measurement of laser peening residual stresses,” journal of materials science and technology, vol. 21, issue 1, p.p.1-23, 2005. [5] dr.aseel jasim mohammed, “effect of laser treatment on fatigue test for composite materials with presence of steel reinforcement,” the iraqi journal for mechanical and material engineering, vol.16, no.1, p.p 1-17, 2016. [6] mahdi noaman muslim shareef, “effect of shot peening on mechanical properties and endurance limit of composite materials,” m.sc thesis, mechanical engineering department, university of technology, baghdad, iraq, 2014. [7] ahmed n. alkhazraji and mahdi n. m. shareef, “comparison of fatigue life behavior between two different composite materials subjected to shot peening at different times,” al-khwarizmi engineering journal, vol. 10, no. 3, pp. 112, 2014. [8] alexander becker, “the effect of laser shock peening and shot peening on the fatigue performance of aluminium alloy 7075,” m.sc thesis, center of materials engineering department, university of cape town, south africa, 2017. [9] abdullahi k. gujba and mamoun medraj, “laser peening process and its impact on materials properties in comparison with shot peening and ultrasonic impact peening,” materials, vol. 7, issue. 12, pp. 7925-7974, 2014. [10] fadhel abbas abdulla, nader majed moustafa and ammar fadhil hussain, “effect of uvradiation on fatigue behavior of natural composite materials,” international journal of mechanical and production engineering research and development (ijmperd), vol. 8, issue 4, pp. 695707, aug 2018. [11] najwa j. jubier, kawakib j. majeed and ekram a. ajaj, “effect of uv irradiation on fatigue behavior of epoxy/ sio2 nanocomposites reinforced with e glass fiber,” international journal of application or innovation in engineering & management (ijaiem) vol. 3, issue 2, pp. 3140, february 2014. [12] hull, d, “an introduction to composite materials,” university of liverpool, cambridge university, england, (1981). [13] w. d. callister, jr, “materials science and engineeringan introduction,” 6th ed, john wiely and sons, inc., new york, (2003). [14] miho tsuyama, yasuteru kodama, yukio miyamoto, ippei kitawaki, masahiro tsukamoto and hitoshi nakano, “effects of laser peening parameters on plastic deformation in stainless steel,” jlmn-journal of laser micro/nanoengineering vol. 11, no. 2, pp. 227231, 2016. [15] qiao hongchao, “experimental investigation of laser peening on ti17 titanium alloy for rotor blade applications”, applied surface science, vol. 351,2015, pp. 524-530. 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[19] american society for testing and materials (astm), “standard test method for tensile properties /d638,” annual book of astm standard, 2003. )2019( 19، صفحة 4د، العد15دجلة الخوارزمي الهندسية المجلم احمد نايف الخزرجي للمواد المتراكبةالخواص الميكانيكية و الكالل سلوك تاثير العصف بالليزر على احمد نايف ابراهيم الخزرجي* عمار عبداالمير مطشر** قسم الهندسة الميكانيكية/ الجامعة التكنولوجية*، ** yahoo.com53dr_ahmed@*البريد االلكتروني: gmail.com1199011ammar@ **البريد االلكتروني: الخالصة المتراكبة البوليمرية شائعةالمواد كون ان تمت دراسته بشكل عملي. حيثتاثير العصف بالليزر على المواد المتراكبة البوليمرية الى هذه الدراسة تهدف مع مسحوق االمنيوم بحجم دقائق ،اساس تم استخدام البولي استر غير المشبع مادةً و بشكل واسع وذلك لسهولة تحضيرها والمتالكها خصائص فريدة االستحدام عملية القولبة اليدوية استخدمت في ، ) %٧٫٥و %٥، %٢٫٥مايكروي كمادة مدعمة حيث استخدم لتحضير نماذج لمواد متراكبة وبكسور حجمية مختلفة ( ) والذي تم قبل وبعد المعالجة الليزية و مع استخدام r=-1اختبار الكالل تم بسعة اجهاد ثابت مع نسبة اجهادات ( .تحضير النماذج باستخدام قالب من الزجاج حيث وصل مقدار الزيادة حوالي %٧٫٥كبة بكسر حجمي ارتي المواد المالكالل ف بمقاومةزيادة ملحوظة النتائج اظهرت و. j)١و j ٢طاقة ليزر مختلفة ( على التوالي بعد المعالجة الليزرية وبمستوى طاقة %١٠٫٥٨٨و %٦٫٤٧٤اعظم اجهاد ومعامل يونك قد ارتفع بنسبة حوالي ان. 1j% عند طاقة ليزر 25 من مسحوق االلمنيوم فقد لوحظ بان الخصائص الميكانيكية ومقاومة الكالل قد انخفضت %٥و %٢٫٥كبة المدعمة ب ارتاما بالنسبة للمواد الم .نفسها ليزرا .2jبعد اجراء المعالجة الليزرية وخصوصا عند طاقة ليزر <4d6963726f736f667420576f7264202d2039342d313032c7cde3cf20e6d8c7e1c820e6e5cfedd1> al-khwarizmi engineering journal,vol. 13, no. 1, p.p. comparative study for organic ahmed faiq al-alala hadeer kadhim mohammed *,*** department of chemical engineering /college of engineering/ **water and environment directorate/ *email: *** received 20 https://doi.org/10.22153/kej.2017.08.007 abstract the present work aims to study forward osmosis process using different kinds of draw solutions and membranes. three types of draw solutions (sodium chloride, sodium formate, and sodium acetate) were used in forward osmosis process to evaluate their effectiveness with respect to water flux and reverse salt flux. experiments conducted in a laboratory-scale forward osmosis (fo) unit in cross flow flat sh film composite (tfc), cellulose acetate (ca), and cellulose triacetate (cta)) were used to determine the water flux under osmotic pressure as a driving force. the effect of temperature, draw solution conce solution flow rate, and membrane types, were studied with respect to water flux. the results showed water flux with increasing feed temperature and draw solution concentrations increasing feed flow rate while the flux showed that reverse osmosis membranes (tfc and ca) are not suitable for using in fo process due to the relatively obtained low water flux when compared with the flux obtained by forward osmosis membrane (cta). nacl draw solution gave higher water flux than other draw solutions and at the same time keywords: forward osmosis, internal concentration polarization 1. introduction fresh water scarcity is a basic problem in many places in the world. one of the most challenges of this century is the increasing for the demand of fresh water for drinking and other utilities such as food production and other industrial needs. presently over one-third of the world’s population suffers of shortage of clean water [1]. therefore one of the most critical challenges of the 21st century is to face the enlarging demand for clean water. osmosis (fo) has been considered as an emerging technology for water reuse and desalination [2, khwarizmi engineering journal,vol. 13, no. 1, p.p. 94102 (2017) organic and inorganic draw solutions in forward osmosis alalawy* talib rashid abbas** hadeer kadhim mohammed*** chemical engineering /college of engineering/ university of baghda environment directorate/ ministry of science and technology email: ahmedalalawy@yahoo.com **email: talibrshd@yahoo.com ***email: hadeer_master@yahoo.com 20 march 2015; accepted 24 august 2016) https://doi.org/10.22153/kej.2017.08.007 the present work aims to study forward osmosis process using different kinds of draw solutions and membranes. chloride, sodium formate, and sodium acetate) were used in forward osmosis process to evaluate their effectiveness with respect to water flux and reverse salt flux. experiments conducted in a scale forward osmosis (fo) unit in cross flow flat sheet membrane cell. three types of membranes (thin film composite (tfc), cellulose acetate (ca), and cellulose triacetate (cta)) were used to determine the water flux under osmotic pressure as a driving force. the effect of temperature, draw solution concentration, feed and draw were studied with respect to water flux. the results showed water flux with increasing feed temperature and draw solution concentrations in addition, the flux increase reasing feed flow rate while the flux was inversely proportional with the draw solution flow rate. the results showed that reverse osmosis membranes (tfc and ca) are not suitable for using in fo process due to the relatively mpared with the flux obtained by forward osmosis membrane (cta). nacl draw solution gave higher water flux than other draw solutions and at the same time, revealed higher reverse salt flux. concentration polarization, reverse salt flux, water flux. fresh water scarcity is a basic problem in many places in the world. one of the most challenges of this century is the increasing for the demand of fresh water for drinking and other utilities such as food production and other third of the ffers of shortage of clean water [1]. therefore one of the most critical century is to face the enlarging demand for clean water. forward osmosis (fo) has been considered as an emerging technology for water reuse and desalination [2, 3]. fo, unlike pressuredriven membrane process is a naturally process of osmosis including semipermeable membrane and a draw solution. the semipermeable membrane, work as a barrier which rejects salts or undesired substances but allows for water to pass through. the mechanism of forward osmosis “physical phenomenon” is water moves through selectively permeable membrane from the low solute concentration feed solution (fs concentrated draw solution (ds) osmotic gradient and retaining the solute on both sides of the membrane. the driving force in fo process is generated naturally due to difference in osmotic pressure between feed and draw al-khwarizmi engineering journal and inorganic draw solutions in talib rashid abbas** baghdad the present work aims to study forward osmosis process using different kinds of draw solutions and membranes. chloride, sodium formate, and sodium acetate) were used in forward osmosis process to evaluate their effectiveness with respect to water flux and reverse salt flux. experiments conducted in a eet membrane cell. three types of membranes (thin film composite (tfc), cellulose acetate (ca), and cellulose triacetate (cta)) were used to determine the water flux ntration, feed and draw were studied with respect to water flux. the results showed an increase in the flux increased with inversely proportional with the draw solution flow rate. the results showed that reverse osmosis membranes (tfc and ca) are not suitable for using in fo process due to the relatively mpared with the flux obtained by forward osmosis membrane (cta). nacl draw revealed higher reverse salt flux. driven membrane process is a naturally process of osmosis-driven which is semipermeable membrane and a draw solution. the semipermeable membrane, ideally, as a barrier which rejects salts or undesired allows for water to pass through. the mechanism of forward osmosis process “physical phenomenon” is water moves through selectively permeable membrane from the low solute concentration feed solution (fs) to the concentrated draw solution (ds) as a result of osmotic gradient and retaining the solute on both sides of the membrane. the driving force in fo process is generated naturally due to difference in osmotic pressure between feed and draw ahmed faiq al-alalawy al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 94102 (2017) 95 solutions, hence this phenomenon offers many advantages like lower energy cost and less membrane fouling potentials [4]. the main benefits of using fo are that the process operates with low or no hydraulic pressure, it have high retaining of wide range of undesired substances and it have lower membrane fouling potentials [4,5]. the flow resistance in the membrane module represents the only kind of pressure in fo process, therefore, the equipments used is very simple and the support of membrane is less of a problem. fo process has also the advantages of concentrating the feed without the need of high pressure or temperature which they may be detrimental to the feed solution [6,7]. in this research we describe the forward osmosis process by using three types of membranes (tfc, ca and cta) and three types of draw solutions, one of them is inorganic (nacl) and the two others are organic (sodium acetate and sodium formate). several researchers used different types of draw solutions for the application of fo process. in previous studies [8,9,10,11,26] the most commonly draw solution used is the inorganic ionic salts such as sodium chloride (nacl) due to the low molecular weight and high solubility. the type of draw solution plays a basic role in fo process, therefore the selection of an ideal draw solution is an important not only in promoting the efficiency of the fo process, but also save cost for the subsequent steps in re-concentration and replenishing the draw solute. an effective draw solution have to possess a very specific characteristics, it should have a high osmotic efficiency which means it has to be highly soluble in water and low molecular weight so as to generate a high osmotic pressure and as a result high water flux and feed water recovery. chemical compatibility of the membrane is another factor for ideality of the draw solution which may degrade or react with the membrane. finally, the processes which involve production of potable water without even traces of solute, the draw solute have to be easily, efficiently and economically be separated and recycled. the attention on draw solutions, as a commercially available, has begun from the late of 1990s, many inorganic salts where used in the fo process. generally, draw solutions from inorganic salts impart high fluxes and can be recovered easily by distillation or reverse osmosis [15,16]. in previous studies [10,11,17,18] the most commonly draw solution used in fo processes were who have lower molecular weight and higher solubility. several inorganic salts were prepared and considered as draw solution in fo processes and the selected salts were then assessed by determining their water fluxes and reverse salt fluxes [18]. organic ionic salt solutions are recently proposed as draw agents in forward osmosis processes. the organic salt is defined as any organic acid (anion) who combined with any inorganic or organic base (cation). the main advantage of using organic salts as draw agent is to reduce the negative influence of the accumulation of draw solute in the feed side due to reverse salt flux and this phenomenon is desirable especially in osmotic membrane bioreactor (ombr) systems for waste water treatment where the organic salt is biologically degraded in the reactor. therefore, the accumulation of organic salts is not an issue when compared with inorganic draw solution [13,27]. generally, the organic salt who have shorter carbon chain overcome the larger carbon chain when they are similar in cation species with the same osmotic pressure. this phenomenon may be attributed to that the former has less icp than the latter according to the higher diffusion coefficient. another advantage for organic salts over their inorganic showed higher salt rejection in the reverse osmosis reconcentration process [14]. to make the technology of fo process advanced, many researchers studied and explored the viability of using other draw solutes [١٣]. hydrophilic magnetic nanoparticles (mnps) were considered one of the great potentials as draw agent [29]. the main advantage of using mnps as draw solute is due to their interest in biomedical applications such as biocatalysis and drug delivery [30]. another type of draw agents were recently studied and developed [31], the polymer hydrogel particles for fo desalination. the hydrogels include three-dimensional network of polymer chains which are linked by either physical or chemical bonds and have the ability to catch large volumes of water via highly concentrated of hydrophilic groups. 2. experimental work 2.1. membrane material 2.1.1 membrane structure three types of flat sheet membranes were used in this study. the first type was thin film composite (tfc) membrane which composed of three layers: a polyamide ultrathin top layer (˂0.5µm), inter micro-porous support layer of polysulfone 40-50 µm, and a polyster fabric ahmed faiq al-alalawy al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 94102 (2017) 96 support ˃120 µm. the second type of membrane was a symmetric cellulose acetate (ca) provided by ge osmonics, ro. this membrane has thick fabric backing layer which provide mechanical support. the membrane is derived from the cseries family, a triacetate /diacetate blend has a higher flux and better mechanical stability than standard cellulose acetate. the third type was asymmetric cellulose triacetate (cta) fo membrane delivered by hti albany, or. the support layer for this fo membrane is comprised of polyster fibers with capacious voids which lead to minimize icp and hence increase permeates flux. the thickness of the membrane is less than 50 µm. 2.1.2. membrane hydraulic permeability the determination of water permeability was experimentally detected using compressed air to press the water through the membrane vertically (hp4750 stirred cell, 300 ml processing volume, 14.6 cm² membrane area, and 69 bar the maximum pressure). the flux of pure water through each membrane was determined under a range of pressures. 2.2 forward osmosis set-up the flat sheet bench scale set-up used in this study as shown in figure 1 was to evaluate forward osmosis performance. the membrane was installed in the membrane holder in fo cell with an effective area of 140 cm2. the cell had a symmetric channels on both sides of the membrane with a dimensions of 140 mm high by 100 mm long by 5mm wide and this configuration allowed for both the feed and draw solution to flow in tangential to the membrane with cocurrent flow to reduce strain on the suspended membrane. the membrane oriented with fo mode where the active layer faces the feed side and the support layer facing the draw solution side. mesh spacer positioned at the feed side to support the membrane and enhance turbulence. fig. 1. schematic diagram of the laboratory-scale forward osmosis setup. two centrifugal pumps were used to recirculate the feed and draw solutions on the opposite sides of the membrane with a flow rate of 1-5 l/min. the draw solution container 2 l capacity was placed on a digital balance with an accuracy of (0.1g) to determine the weight changes of the draw solution with time in order to calculate the permeate flux. the operating temperature for both feed and draw solutions was varied between 15-40°c and the duration for each experiment was 4 h in batch mode. the temperature for both feed and draw solutions was measured and controlled by microcomputer temperature controller (accuracy ±1˚c) using cooler and heater connected to coils immersed in both solutions to keep the desired temperature. a ahmed faiq al-alalawy al-khwarizmi engineering journal, vol. 13, no. 1, p.p. conductivity meter (ec-meter, basic 30, crison spain, accuracy ± 5%) used to measure the concentration of salts in draw solution and feed periodically and hence determine the reverse salt flux with time. 2.3. feed and draw solutions distilled water was used as feed in all the experiments (conductivity, 12 µs/cm) three kinds of draw solutions were used, sodium chloride, sodium acetate, and sodium formate dissolved in distilled water. the chosen draw solutes, as specified in table 1, possess the same cation (na) so as to be obvious and easier in comparison with respect to water and salt fluxes. the concentration of the draw solutions for all the three type varied between 0.3 m to 2 m. table 1, chemical specifications of draw solutions sodium chloride nacl mw = 58.44 g/mol solubility = 355 g/l (h2o) assay 99.5% (min) maximum limits of impurities (%): ammonia iron lead potassium sulphate 0.02 sodium formate hcoona mw= 68.03 g/mol solubility = 972 g/l (h2o) ph = 7.0-8.5 assay 98% (min) maximum limits of impurities (%): chloride 0.01 sulphate 0.05 sodium acetate ch3coona mw= 82.03 g/mol ph=7.5-9.2 solubility= 1233 g/l (h2o) assay 99% (min) maximum limits of impurities (%): chloride phosphate sulphate calcium iron potassium 3. results and discussions 3.1. membrane permeability the results of the permeability were determined from the curve slope tests for tfc, ca, and cta membranes which were and 0.73 l/m²h.bar, respectively, as khwarizmi engineering journal, vol. 13, no. 1, p.p. 97 meter, basic 30, crison spain, accuracy ± 5%) used to measure the concentration of salts in draw solution and feed periodically and hence determine the reverse salt as used as feed in all the (conductivity, 12 µs/cm) while were used, , and sodium dissolved in distilled water. the , as specified in table 1, the same cation (na) so as to be with respect water and salt fluxes. the concentration of the draw solutions for all the three types was chemical specifications of draw solutions. assay 99.5% (min) maximum limits of impurities (%): 0.002 0.002 0.0005 0.02 assay 98% (min) maximum limits of impurities (%): chloride 0.01 sulphate 0.05 assay 99% (min) maximum limits of impurities (%): chloride 0.001 phosphate 0.0005 sulphate 0.0003 calcium 0.001 iron 0.0005 potassium 0.02 the results of the permeability were determined from the curve slope tests for tfc, ca, and cta membranes which were 6.6, 4.7, shown in figure 2. the results showed that the permeability of the tfc and ca membranes is much greater than cta membrane. these results prove that tfc and ca (reverse osmosis) membranes give high fluxes under hydraulic pressure and cta (forward osmosis) membrane g fluxes under osmotic pressure. fig. 2. pure water flux against applied pressure for determine permeability coefficient (a): t membrane, ca membrane, and cta membrane. 3.2. effect of temperature the effect of temperature on water shown in figure 3. the experiments were carried out using three types of membranes ( tfc, ca, and cta) with variable temperature for both feed and draw solutions (15-40˚c). khwarizmi engineering journal, vol. 13, no. 1, p.p. 94102 (2017) re 2. the results showed that the permeability of the tfc and ca membranes is much greater than cta membrane. these results prove that tfc and ca (reverse osmosis) membranes give under hydraulic pressure and cta (forward osmosis) membrane give satisfactory 2. pure water flux against applied pressure for determine permeability coefficient (a): tfc ca membrane, and cta membrane. temperature on water flux is the experiments were carried out using three types of membranes ( tfc, ca, and cta) with variable temperature for both feed ahmed faiq al-alalawy al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 94102 (2017) 98 fig. 3. water flux in function of temperature for different membranes (0.6 m nacl, 3 l/min feed and draw flow rate). according to figure 3, the water flux increase with temperature linearly and this attributed to decrease in viscosity of the feed water and this lead to increase in diffusion rate for water through the membrane outcoming in a higher permeability which is compatible with previous studies [19]. the temperature will have clear impact on icp which become lower at higher temperature and hence higher water flux. we notice that the effect of temperature on water flux is greater when using cta membrane when compared with ca and tfc membranes. the reason for this difference in fluxes is expected to the thick fabric and porous support layers in ca and tfc membranes which contribute to the development of internal concentration polarization (icp) and therefore reduce the effective driving force and water flux. figure 4 illustrates the water flux for tfc, ca and cta membranes at different kinds of draw solutions using the same experimental conditions. 3.3. effect of concentration figure 4 shows that an increase in water flux was found when the concentration of the draw solution increased from 0.3 m to 1.5 m due to an increase in the osmotic driving force over the membrane (since osmotic pressure difference is the driving force in fo operation). as illustrated in figure 4, the plots show that the flux is almost linear and the deviation from the linearity is due to the effects of icp, which reduces the effective driving force of the draw solution. fig. 4. influence of draw solution concentration on water flux with different types of draw solutions and using different membranes: cta membrane, ca membrane, and tfc membrane {30 °c±1 temperature, 3 l/min flow rate}. the results indicate that water flux depend not only on concentration of draw solution but also on the kind of draw solution. we notice from plots that the water flux for sodium chloride is greater than sodium acetate and sodium formate. this could be due to a higher solute diffusion coefficient resulting in greater efficiency of nacl than other draw solutes. therefore, it can be deduced that the organic sodium salts with larger sizes have lower diffusion coefficients which are more affected by icp than nacl. ahmed faiq al-alalawy al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 94102 (2017) 99 3.4. effect of draw solution figure 5 represent the reverse salt flux with time for the three types of draw solutions. the figure shows higher salt flux for nacl than other draw solutes and sodium acetate revealed lower salt flux. reverse salt diffusion increase with increasing draw solution concentration due to the increasing in driving force. fig. 5. influence of draw solution concentration on reverse salt flux for different kinds of draw solutions (30°c temperature, 3 l/min flow rate, cta membrane). 3.5. effect of feed flow rate figure 6 illustrates the effect of feed flow rate on water flux using different types of membranes. fig. 6. effect of feed flow rate on water flux with different membranes (30°c temperature, 0.6 m nacl). feed velocity shows small effect on water flux and this may attributed to low concentration of salt of the feed and as a result reveal little contribution of concentrative external concentration polarization (cecp) to the flux. 3.6. effect of draw solution flow rate figure 7 shows the influence of draw solution flow rate on water flux. the results reveal increasing of water flux with decreasing of draw solution flow rate and this may attributed to increasing the concentration build up in the vicinity of the membrane surface. this process leads to increasing the osmotic pressure in the draw solution side and hence increasing water flux. fig. 7. effect of draw solution flow rate on water flux at different membranes (30°c temperature, 0.6m nacl). the permeate water flux was assessed for the three membranes using nacl as draw solution as shown in figure 8. every membrane was tested in a cross flow mode with 0.6 m concentration of draw solution against distilled water as feed solution. the feed solution was coordinated against the active layer of the membrane and the draw solution was against the support layer. both the feed and draw solutions were kept up at 30°c and water flux been determined with time for the under the same test conditions. the cta membrane had a quite higher water flux than either tfc or ca membranes. fig. 8. water flux against time for different kinds of membranes (30 °c temperature, 3 l/min flow rate, and nacl draw type). ahmed faiq al-alalawy al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 94102 (2017) 100 the difference in flux between these membranes is due to the difference in structures of the membranes, where the overall thickness of the cta membrane is less than 50 µm (consist of two layers of cellulose triacetate polymer embedded with polyster mesh as support) which is less than thickness of tfc and ca membranes (140 µm) which is composed of thick fabric and porous support layers. it is concluded that these thick support layers of tfc and ca membranes may contribute to the development of internal concentration polarization and as a result reduce the effective driving force and water flux respectively. figure 9 shows differences in salt flux values between tfc, ca, and cta membranes and this imparity is attributed to structure of the separating layer of the membranes. the separating layer for the fo-type membrane (cta) is less compact when compared to other ro membranes (tfc and ca) and this result reflected in lower retention ability for fo membranes than ro membranes. fig. 9. change of reverse salt flux with time for different types of membranes (30 °c temperature, 3 l/min flow rate, 0.6 m nacl). 4. conclusions the permeability flux for osmotically driven cta membrane is higher than tfc and ca membranes, while the flux increased dramatically for tfc and ca membranes and become much higher than cta membrane when hydraulic pressure applied. the reverse salt flux for cta membrane is higher than ca and tfc membranes. in this research, the draw solutions characteristics state that inorganic ionic salt (nacl) impart little higher flux than organic ionic salt (sodium formate) but much higher than other organic salt (sodium acetate) while the results which obtained for reverse salt flux gave high values for sodium chloride salt when compared with other organic salts which considered drawback for nacl salt. acknowledgements the authors acknowledge the support of the chemical engineering department, college of engineering, university of baghdad. the authors also acknowledge the water and environment directorate, ministry of science and technology. 5. references [1] t.s. chung, x. li, r.c. ong, ge, h.l. wang, g. han, emerging forward osmosis (fo) technologies and challenges ahead for clean water and clean energy applications, curr. opinion chem. eng. 1 (2013) 246-257. 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[29] m.m. ling, t.s., chung, desalination process using super hydrophilic nanoparticles via forward osmosis integrated with ultrafiltration, desalination 278 (2011) 194202. [30] dan li et al., stimuli-responsive polymer hydrogels as a new class of draw agent for forward osmosis desalination, chem. commun. 47 (2011) 1710-1712. � ا����ي � � �� 1، ا���د13���� ا���ارزم� ا������� ا� ��م ا��� ،102-94 )2017( 102 ��) ا�'�& ا��"�!� وا�$#"�!� � درا�� م ر������ م��+� �* ا(م ا �� # � ا����يأ� � � **ط �& ر/�� #. س *��*ھ�!4 3 ظ1 م و�� *** ،* ��� �� ���اد / ���� ا������ /��� ا������ ا�� � ** / هدا#"ة ا� ��� وا�����%�� وزارة ا���%م وا�& ahmedalalawy@yahoo.com : ا,� &"و+* ا� "��* talibrshd@yahoo.com : ا,� &"و+* ا� "�� ** hadeer_master@yahoo.com : ا,� &"و+* ا� "��*** �� ا��$ ��0 ���ف ا� .-.� 1� �2�&3��* ��5&�3ام ا+%اع � ��0 ا��.: +=<=� ا. وا,>;��ا��.: ا�9 درا�� 8���� ا�&� 67 ا,.� 1�، ��%ر�� ا�?%د�%م( %اع �* وذ�c ) وb<ت ا�?%د�%م ، 7%ر��@ ا�?%د�%م �2 ءة ھ6ه ا��. ��e&� 0%��ا�&�3�@ 7* 8���� ا�&� 67 ا,�h�"ل 18 ط�����ل h7�k ا�� ء و� ب �m �<ح>� *� �3& "�� ��&� 67 ا,. ا�&�h7 ا�� رب ا�"�@ 7* و�mة o&ا�pq�� *e ء ط �0 و>;e&� ن �"��* ��5&�3ام �b�� ذات � . @�=<=� ا+%اع �1 ا�&�3 ��ل h7�k ا�� ء و�b 1<ل ا�t�u (cta) و����%ز k"اي ا��&�@ (ca) ����%ز ا��&�@ ,(tfc) ا,>;�� ھ* ا��; ء ا�"��h ا��"�:� ب �.� �.�%ل ا��.: و5k=�" در�� ا�."ارة و �%ة دا7���%v2w ا,وز�%زي x��"k ل ا��.: و%�.� ن ا��e�� و�"���ل ��b 1<ل ، و+%ع ا��; ء �k درا�&� ��ل h7�k ا�� ء� ب �m . @.yاو ��eارة ا��"m ����ل h7�k ا�� ء �z ز� دة در��.�%ل ا��.: v+�2 و�c�6 ا�& =�"ا��& #] ز� دة 7* x��"k دة �x� ث�.� ، �7 y] � � h7�&ل ا���� ن �.�%ل ا��.:ا�9 ذ�c 57ن �"���ل ��z ز� دة ً �� %ن ا�&=5�8 "� ���� ��eن ا�� �"���ل �ا��& #] اظ�"ت �5ن . xداد �z ز� دة �* أ>;��� � ((tfc,ca ا�&� py ا��� a�� 2��y h7�k ل��� *q�k �+b cوذ� *� � �b&�3ا�v 7* 8���� ا�&� 67 ا, h7�&ل ا���� z� ر+� e�� ء ���� [k ء8ا��;< 1 cta . @�%7* ا� .و7* ا� �� ��0 ا��.: ا,b"ى ا���&�3.� 1���ل h7�k ا9�8 ��� ء � 9q8ل ا��.: ��%ر�� ا�?%د�%م ا%�.� v�2+ �� 8 h7�k ل��� �%ر�� ا�?%د�%م اظ�"ت ا��را�� � � ��� .ا9�8 �<�<ح � (microsoft word \321\324\307 \321\307\343\322123128) al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 14, no. 3, september, (2018) p.p. 123128 investigation of cnc milling machining parameters on surface roughness rasha ramiz alyas department of production engineering and metallurgy / university of technology/ baghdad/ iraq safaa_kadhim1988@yahoo.comemail: (received 20 june 2017; accepted 13 january 2018) https://doi.org/10.22153/kej.2018.01.008 abstract milling machining is a widely accepted nontraditional machining technique used to produce parts with complex shapes and configurations. the material is removed in two stages roughing and finishing, the flat end cutter removed the unwanted part of material, then finished by end mill cutter. in milling technique, the role of machining factors such as cutting depth, spindle speed and feed has been studied using taguchi technique to find its effectiveness on surface roughness. practical procedure is done by taguchi standard matrix. cnc milling is the most conventional process which is used for removing of material from workpiece to perform the needed shapes. the results and relations indicate that the rate of feed is very important factor for modeling surface roughness. the plot of s/n ratio shows that the optimum combination of the milling factors that gives the best value of surface accuracy. the best combination of milling factors has also been predicted to minimize the surface roughness. keywords: orthogonal array, surface roughness, s/n ratio, taguchi technique. 1. introduction producing components with complex surfaces don’t like producing parts with regular surfaces. this is because the big difference between complex and regular surfaces, or the freedom in designing of the complex surfaces. now days the technique of cnc machines has been widely used in various manufacturing fields to meet the advance requirements, especially in accurate metal forming industry. furthermore, geometric features made of complex surfaces are often produced in combination, whilst those with regular shapes are normally machined individually [1, 2]. the requirements for high performance and automated machining systems interested with the surface conditions of the part, product roughness of the machined parts is most important because of the effect on part shape, function, and product life. it is the most general used in a wide number of manufacturing processes. milling is the popular widely used metal cutting process [3]. this paper reveal the role of some of machining factors like (feed rate, depth of cut and spindle speed) on surface roughness in cnc milling process. for these causes it is an important to keep the surface finish and consistent clearances. between many cnc production machining techniques, milling process is a good machining technique. an important role in performance of machining, the nature of the surface plays as a bestaccuracy machined surface significantly improves fatigue strength, creep life and corrosion resistance. the resulted surface from milling is affected by many parameters like temperature, vibration, rotational speed, tool shape, feed, tool path, cross-feed and other factors [4]. machining parameter specified range plays an important action on surface quality. in milling, use of low depth of cut, high spindle speed and low feed rate are recommended to find out best surface roughness for the specified range in a material. as the applied force increased surface roughness is increased. if we used a small rasha ramiz alyas al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 123128 (2018) 124 nose radius at constant feed cause the higher surface roughness, with the modern production requirements of modern industries; the control of surface roughness with the surface accuracy became more important matter [5,6]. cutting speed is the most important parameters that effect on surface roughness. the most important combinations that affect product roughness are between the depth of cut and cutting speed, and between spindle speed and feed rate. this practical investigation demonstrates the taguchi optimization technique, which is applied to find the best surface roughness in end milling operation [7]. aluminum alloy was the workpiece and the experiment is conducted on it by (hss) tool with finishing pass. the machining conditions such as feed rate, rotational speed and cutting depth. taguchi l9 orthogonal array was used to conduct the experiments. 2. experiment and data collection the experiments were designed using l9 taguchi orthogonal array. minitab16 was the technique that used for arrangement of experiment. working within the minitab16 program is done in three stages. these stages are firstly the planning stage, secondly the conducting stage, finally the analyzing stage. a) planning stage in the planning stage, the cutting factors are set according to their level and according to the table (1) which includes the cutting factors (rotational speed, feed, cutting depth). table 1, selected input parameter factor a ( rpm) factor b (mm/min) factor c (mm ) 1000 100 1 1250 150 1.5 1500 200 2 b) experiments of design taguchi l9 orthogonal array was used for selected input parameters experiments design as shown table (2). for this purpose, minitab software 16 was used: table 2, experiments design using minitab software. exp. no rotational speed(rpm) (a) feed (mm/min) (b) cutting depth(mm) (c) 1 1000 100 1 2 1000 150 1.5 3 1000 200 2 4 1250 100 1 5 1250 150 2 6 1250 200 2 7 1500 100 2 8 1500 150 1 9 1500 200 1.5 c) workpiece material the workpiece that used in the present paper is aluminum alloy with dimensions (50 x 50 x 25 mm). whose compositions are as follows: si 1.1% cu 4.5% rest al and has mechanical properties as follows: tensile strength = 221 (mpa) yield strength = 110 (mpa) ductility = 8.5 (%elongation in 50 mm) applications crankcases, flywheel, bus, axle housing and aircraft parts. d. experiments set up the completion of the nine samples on the cnc milling machine the surface roughness values are taken and by determining the least readability of the roughness, which is the best value, the best factors are determined through the prediction by the program minitab. the value of s/n ratio (means that the amount of the output signal (resulting from the process) to the error rate and the greater the value, the better the reading of the prediction) of each experiment was calculated based on equation no.1. fig 1. cnc machine. rasha ramiz alyas al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 123128 (2018) 125 the equation is sni = 10ـــ x log ( � � ∑ � ��� y2 i ) ... (1) where n = number of measurements in a trial/row, in this case, n=3, sni is the signal to noise ratio of ith term, and yi is the ith value of measured in a run/row [8]. 3. apparatus used to calculate roughness measurements the important output properties that can be measured is surface roughness which measured in the present paper by using pocket surf the portable surface roughness gage mahr federal’s patented that shown in figure (2) below. the mahr federal’s is a surface-roughness measuring apparatus, which moves on the surface of machined parts to measure the surface roughness depending on standards, later the results displayed on lcd display. in addition, a reading of ra was taken, which gives a passage on the surface and gives a rate of surface roughness as shown in table (3), which is considered the most widely used industry. the stylus moves a specified displacement during the movement the data processed and appear on a gage liquid crystal display. fig 2. pocket surf tester table 3, surface roughness value for each experiments. no rotational speed (rpm) (a) feed (mm/min) (b) cutting depth (mm) (c) surface roughness (r1) (μm) r2 r3 s/n ratios (dbi) means 1 1000 100 1 1.781 1.975 1.927 5.55471.89433 2 1000 150 1.5 2.340 2.482 2.359 7.58432.39367 3 1000 200 2 2.730 2.292 2.482 7.98572.50133 4 1250 100 1 1.001 1.299 1.273 1.57351.19100 5 1250 150 2 1.027 1.839 1.405 3.29781.42367 6 1250 200 2 1.157 1.283 1.284 1.88781.24133 7 1500 100 2 0.455 0.628 0.691 4.4414 0.59133 8 1500 150 1 0.676 0.761 0.934 1.9644 0.79033 9 1500 200 1.5 4.017 4.126 4.938 12.82884.36033 rasha ramiz alyas al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 123128 (2018) 126 fig 3. s/n ratio plot fig. 4. means plot. figure (3) shows the relationship between input parameters and s/n ratio data. while figure (4) in this diagram, the relationship between the surface roughness value rate and each of the cutting factors is indicated with their levels and by the lowest roughness value that gives the value of the factor to the best reading. the aim of using s/n ratio as a measurement of performance is to develop a process in sensitive to noise factor. the best input parameters can be found of combination from plot (3) i.e. plote between input parameters and s/n ratio, the optimum setting of process parameters are (a2b1c1). the selected parameters with the highest s/n ratio generally yields the optimum quality with minimum variation. 4. calculation of the performance the effect of all factors on surface roughness is found according to the following equation [9]: average performance of factor a at level 1= �� � � � ����� �� ��� � ������ ... (2) according to the minitab program, the most effective factor is calculated on the cutting process known as rank and according to table (4). the following table shows the most effective factor is the cutting depth (rank 1) and the lowest factor is the cutting speed (rank 3). table 4, table for signal / noise ratio minimum of s/n ratio is better level of parameter a b c 1 -7.0424 -0.8965 -1.7222 2 -2.2530 -2.9726 -10.2065 3 -2.1410 -7.5674 -2.1825 delta 4.9015 6.6710 8.4844 rank 3 2 1 5. calculation of optimal surface roughness let r = surface roughness average result for 9 runs r � ∑ ���������� � ! " = 1.8208 6. result and discussion using these data the best surface roughness can be predicted using the optimum machining conditions mentioned above and according to the relation: predicted mean (ra) = a2 +b1 +c1– 2(average mean) ...(3) where a2= average of (ra) at the second level of spindle speed b1= average of (ra) at the first level of feed rate c1= average of (ra) at the first level of depth of cut from table (7): predicted mean (ra) = 1.285+1.226+1.2922*1.8208= 0.1614 µm 7. conclusions 1. the plot of s/n ratio show that the optimum value of surface quality is found at first value of factor b, the second value of factor a and first value of factor c. rasha ramiz alyas al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 123128 (2018) 127 2. from the results it can be seen that the optimum value of surface roughness is 0. 0.1614 μm. 3. taguchi technique is the best way to determine the number of samples by introducing the effects with their levels to determine the minimum number that can be run through its matrices. the taguchi method is widely used and found to be suitable for determining the cutting effects of the programmed milling machine. 8. references [1] dalgobind mahto and anjani kumar,” optimization of process parameters in vertical cnc mill machines using taguchi’s design of experiments”, ariser vol. 4 no. 2 (61-75,2008 [2] tao ye, cai-hua xiong,” geometric parameter optimization in multi-axis machining”, computeraided design 40 (2008) 879–890,2008 [3] s. doruk merdol, yusuf alt,” virtual cutting and optimization of three-axis milling processes”, international journal of machine tools & manufacture 48 1063– 1071,2008 [4] h.-s. lu, j.-y. chen, ch.-t. chung,” the optimal cutting parameter design of rough cutting process in side milling”, volume 29 issue 2, 2008 [5] m.a. lajis, a.n. mustafizul karim, a.k.m. nurul amin, a.m.k. hafiz, l.g. turnad,” prediction of tool life in end milling of hardened steel aisi d2”, issn 1450-216x vol.21 no.4, pp.592-602,2008 [6] j. v. abellan, f. romero, h. r. siller, a. estruch and c. vila,” adaptive control optimization of cutting parameters for high quality machining operations based on neural networks and search algorithms”, isbn 78-953-7619-16-9, pp. 472, i-tech, vienna, austria,2008 [7] guillem quintana, joaquim ciurana , daniel teixidor,” a new experimental methodology for identification of stability lobes diagram in milling operations “,international journal of machine tools & manufacture 48 (2008) 1637–1645,2008 [8] m.kurt & e.bagci & y.kaynak, “application of taguchi methods in the optimization of cutting parameters for surface finish and hole diameter accuracy in dry drilling processes”, int. j adv. manufacturing technology -1368-2, (2007). [9] m.t. hayajneh, m.s. tahat, j. bluhm, “study of the effects of machining parameters on the surface roughness in the end-milling process”, jordan journal of mechanical and industrial engineering, (2007). )2018( 123-128، صفحة 3د، العد14دجلة الخوارزمي الهندسية المجلم رشا رامز الياس 128 تأثير متغيرات التشغيل في مكائن التفريز المبرمجة على الخشونة السطحية الياسرشا رامز قسم هندسة اإلنتاج والمعادن / الجامعة التكنولوجية yahoo.com1988safaa_kadhim@ البريد االلكتروني: الخالصة واالنهاء القطع الخشن ازالة المادة تتم على مرحلتين. معقدة أجزاء ألشكال إلنتاج المستخدمة للقطع التقليدي مقبولة أكثر تقنية هو مكائن التفريز في االنهاء السطحي يتم استخدام عدة قطع ذو نهاية ثم العينة، من المطلوب الجزء مسطحة وإزالة القطع الخشن يتم استخدام عدة قطع ذونهاية السطحي، . السطحية للخشونة قيم افضل إليجاد تاكوشي تقنية باستخدام والتغذية القطع ةوسرع القطع عمق مثل التشغيل عوامل تأثير دراسة تم هذا البحث، في. مستديرة المشغولة من المعدن إلزالة تستخدم التي تقليدية األكثر العمليات هو التفريز بالمكائن المبرمجة. القياسية تاكوشي مصفوفة قبل من العملي تحديد الجزء يتم االشارة للخشونة الى معدل نسبة وتظهر. السطح خشونة للتأثير على جدا مهم عامل هو التغذية معدل أن إلى تشير والعالقات النتائج. المطلوبة األشكال النتاج .سطحية خشونة افضل التي تعطي عوامل أفضل توقع تم كما. السطح لدقة قيمة أفضل تعطي التي القطع عوامل بين األمثل تعطيالخطأ 1-14 al-khwarizmi engineering journal,vol. 12, no. 1, p.p. 1 enhancement of buckling resistance ahmed naïf al hameed shamkhi al *,** department of mechanical engineering / university of technology ** department of machines and equipment / (received abstract this paper has investigated experimentally the dynamic buckling behavior of aisi 303 stainless steel aluminized and as received long columns. these columns, hot 22 specimens, without aluminizing (type 1), and 50 specimens, with hot conditions of dipping temperature and dipping time (type 2), are tested under dynamic compression loading and under dynamic combined loading (compression and bending) by using a rotating buckling test machine. the experimental results are compared with perry robertson interaction formula that used for long columns. get a mathematical model that descripts the buckling b loading. the experimental results obtained show an advantageous influence of hot dynamic buckling behavior of aisi 303 stainless steel long columns. critical buckling stress, are as follow: (64.8 %) for long columns type (2), compared with columns type (1), under dynamic compression loading, and (56.6 %) for long columns type (2), combined loading, and (33.3 %) for long columns type (2) compared with keywords: dynamic buckling, hot-dip aluminizing, long columns, aisi 303 stainless steel. 1. introduction structural members subjected to axial compressive loads may fail in a manner that depends upon their geometrical properties rather than material properties [1]. it common experience, for example, that a long slender structural member will suddenly bow with lateral displacements when subjected to an axial compression load [1, 2]. long slender members subjected to an axial compressive force are called columns, and the lateral deflection that occurs is called buckling [3]. the buckling behavior of steel columns consider one of the important khwarizmi engineering journal,vol. 12, no. 1, p.p. 114 (2016) buckling resistance of aluminized long columns stainless steel aisi 303 ahmed naïf al-khazraji* samir ali alrabii** hameed shamkhi al-khazalli*** department of mechanical engineering / university of technology department of machines and equipment / institute of technology / middle technical university / baghdad *email: dr_ahmed53 @yahoo.com *email: alrabiee202@yahoo.com ***email: hameedshamkhi@yahoo.com (received 11 june 2015; accepted 4 august 2015) this paper has investigated experimentally the dynamic buckling behavior of aisi 303 stainless steel aluminized and as received long columns. these columns, hot-dip aluminized and as received, are tested under dynamic buckling, 22 specimens, without aluminizing (type 1), and 50 specimens, with hot-dip aluminizing at different aluminizing conditions of dipping temperature and dipping time (type 2), are tested under dynamic compression loading and under mpression and bending) by using a rotating buckling test machine. the experimental results are compared with perry robertson interaction formula that used for long columns. greenhill formula is used to get a mathematical model that descripts the buckling behavior of the specimens of type (1) under the experimental results obtained show an advantageous influence of hot-dip aluminizing treatment on dynamic buckling behavior of aisi 303 stainless steel long columns. the improvement based on the average value of critical buckling stress, are as follow: (64.8 %) for long columns type (2), compared with columns type (1), under 56.6 %) for long columns type (2), compared with columns type (1), combined loading, and (33.3 %) for long columns type (2) compared with perry robertson critical buckling stress. dip aluminizing, long columns, aisi 303 stainless steel. structural members subjected to axial compressive loads may fail in a manner that depends upon their geometrical properties rather than material properties [1]. it common experience, for example, that a long slender structural member will suddenly bow with large lateral displacements when subjected to an axial compression load [1, 2]. long slender members subjected to an axial compressive force are called columns, and the lateral deflection that occurs is the buckling behavior of columns consider one of the important phenomenon that had been studying and analysis from a long time. for combined axial and bending loads, european standard (eurocode 3 env 1939 1-4), american standard (sei/asce 8 australian/ new zealand standar are suggested to use the guidance developed for carbon steel to determine the resistance of stainless steel members [ experimentally tests are carried on cold formed austenitic stainless steel square, rectangular, and circular hollow section members to examine the buckling behavior of columns and beams under effect of gradually increased single and combined loads (compression, bending, and compression bending) with two types of ends conditions pin al-khwarizmi engineering journal (2016) long columns of rabii** department of mechanical engineering / university of technology middle technical university / baghdad this paper has investigated experimentally the dynamic buckling behavior of aisi 303 stainless steel aluminized dip aluminized and as received, are tested under dynamic buckling, dip aluminizing at different aluminizing conditions of dipping temperature and dipping time (type 2), are tested under dynamic compression loading and under mpression and bending) by using a rotating buckling test machine. the experimental greenhill formula is used to ehavior of the specimens of type (1) under dynamic compression dip aluminizing treatment on based on the average value of critical buckling stress, are as follow: (64.8 %) for long columns type (2), compared with columns type (1), under compared with columns type (1), under dynamic critical buckling stress. phenomenon that had been studying and analysis for combined axial and bending loads, european standard (eurocode 3 env 19394), american standard (sei/asce 8-02), and australian/ new zealand standard (as/nze 4673 are suggested to use the guidance developed for carbon steel to determine the resistance of stainless steel members [4]. a series of experimentally tests are carried on cold formed austenitic stainless steel square, rectangular, and hollow section members to examine the buckling behavior of columns and beams under effect of gradually increased single and combined loads (compression, bending, and compressionbending) with two types of ends conditions pinahmed naïf al-khazraji al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 114 (2016) 2 ends and fixed-ends [5]. the buckling of solid and hollow ck35 and ck45 alloy steel columns under combined dynamic loading has been studied experimentally and the obtained results showed that the failure resistance of the columns depends on the type of cross-section and initial deflection of column [6]. the nitride case hardening (liquid nitriding) surface treatment is used to enhance the buckling resistance of square columns with different length, material (ck45, ck67, ck101), and constant cross section (10 ×10) mm subjected to the effect of single and combined dynamic loads. the results of the study showed experimentally that the resistance and the number of cycles to failure were increased by using this method [7]. the surface treatment by shot peening is used to enhance the buckling resistance of a series of (ck35) steel column with solid circular cross-section under single and combined dynamic loads by increasing the yield and ultimate strength of columns material [8]. because of the many practical applications of stainless steel columns in constructions of the buildings, ships, bridges, airplanes, spaceships, etc., there were many of studies and researches to improve the buckling resistance of columns by using of number of methods, for example: • improvement of the mechanical properties of the columns material by using new special metal alloys, or by using of composite materials. • improvement of columns section design by using of the modern design methods that increases of the columns resistance to the buckling. • using of the surface treatments methods such as: shot-peening and heat treatment. surface coating is an efficient and economical way to obtain the desirable material properties by altering physical, chemical, or electrical characteristics of a material. surface modification by coatings has become an essential step to improve the surface properties such as, resistance to wear, corrosion and oxidation [9, 10].the influence of surface coating treatment on the surface properties and some of the mechanical properties was investigated by many researchers. a new pack cementation process technique was used to enhance the hot corrosion and oxidation resistance of stainless steel aisi 316l by using two different kinds of coating, the first one was si-modified aluminide coating and the second was the ce-deped silicon modified aluminide coating [11]. hot dip aluminizes samples with (1-6 wt %) silicon concentration of aluminizing melt and samples aluminized in pure aluminum were tested by using a 3-point bend device in order to compare the relative ductility and formability of the aluminized steel and to determine the influence of silicon concentration and coating thickness on these properties [12]. there are many fields of practical applications that needs to use of steel columns meet between the strength and resistance of the external environment conditions (corrosion, wear, and high temperature oxidation). from this point of design, the designer used numbers of procedures to maintain the above requirements. the surface coating by using aluminum (aluminizing process) was one of the popular methods to develop protection layer for substrate material from environment conditions. this paper examine the effect of hot-dip aluminizing process (hda) on dynamic buckling of long columns subjected to compression and compression-bending loads, of stainless steel (aisi 303) material by series of circular crosssection columns, of different slenderness ratio, with and without hda surface treatment at different dipping temperatures (���) and dipping times (���). 2. theory 2.1. perry robertson interaction formula it is important to evaluate the compressive buckling strength of real columns,���, in the presence of initial mechanical and geometrical imperfections, a perry robertson interaction formula [4, 13, 14, and 15] is adopted as follow: ��� = �� … �1� and ��� = � × ��� … (2) where: = 1 � + ��� − ������.� ≤ 1 … �3� in which: � = 0.5 !1 + "!� − �#$ + ����$ … �4� � = �&' . (�� ) … �5� where the value of the imperfection factor (") and the limiting non-dimensional slenderness ratio are defined in table (1). the value of the effective slenderness ratio (�&) is calculated by using the relation [3]: �& = *+� = +,� … (6) ahmed naïf al-khazraji al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 114 (2016) 3 the value of slenderness ratio above which column’s type is long is obtained using the following relation [16]: �� = �& = '.)�./ … �7� and by substituted the value of e, �./ from table (2), and the value of k=0.7 (for fixed-pinned ends) in eq. (7), we find that the value of critical slenderness ratio is �� = 86.5. table 1, values of imperfection factor and limiting slenderness ratio for flexural, torsional and torsionalflexural buckling [14]. buckling mode type of member 3 45 flexural cold formed open sections hollow sections (welded and seamless) welded open sections (major axis) welded open sections (minor axis) 0.49 0.49 0.49 0.78 0.40 0.40 0.20 0.20 torsional and torsional-flexural all members 0.34 0.20 2.2. spatial buckling under torque and axial force spatial buckling of twisted and compressed shafts is important for the design of rotors of turbines, generators, and other rotating machinery. spatial buckling may also be important for frames. recently, design of latticed struts that can be collapsed for transport by means of torsion became of interest for construction of an orbiting space station [17]. consider a geometrically perfect beam or shaft supported on two spherical hinges, loaded by axial force p and torque 67, which is assumed to keep its direction during buckling; see fig. (3-10), where the axial vector of torque is represented by a double arrow. according to greenhill (1883), the relation between the buckling load p and torque 67 is given by [17]. ����� + 8676��� 9 � = 1 … �8� where ���� = :;<=+; 6��� = > :<=+ … (9) ���� is the critical load for buckling without torque (euler formula), and 6��� is the critical torque for buckling without axial force. equation (8) is plotted in fig. (1). by using effective length (?&� instead of (l), eq. (8) can be used to determine the theoretical buckling load (�) for other form of ends support. from eqs. (8) and (9), one can be write � = 81 − @abacde f�9 ∗ ���� … (10) and > = ab∗+,:<=∗�hi jjcde �k/m … (11) in this work, k consider as a function of buckling parameters in order to fit the experimental results with a mathematical model. 3. experimental work 3.1. material used and buckling test machine aisi 303 stainless steel as long columns of circular cross-section, ø=8 mm, of different slenderness ratio (λ�, with and without hot-dip aluminizing were tested by using rotating column buckling test machine capable to apply compression and compression-bending dynamic loads, with column ends support of fixedpinned and rotating speed of 17 and 34 r.p.m. in this research it was used low speed (17 r.p.m) in all dynamic buckling experiments. the photograph of the rotating buckling test machine is shown in fig. (2). more details of buckling test machine, used in this research, were found in ref. [6]. the detail of the chemical composition of stainless steel; tested and standardized in state company for inspection and engineering rehabilitation (sier)/ baghdad by a certificate no. 1043/2013 at room temperature (25 ℃) and relative humidity (60%), is shown in table (2). also, the significant fig. 1. beam or shaft subjected to axial force and constant-direction torque [17]. ahmed naïf al-khazraji mechanical properties, tested in central organization for standardization and quality control (c.o.s.q.c.) / baghdad, are given in table (3). while the experiments of hot dip aluminizing aisi 303 stainless steel carried out , by using a self-construction system of hotdip aluminizing, fig. (3), in state company for electrical industries/baghdad/ unit of casting. a high purity aluminum (99 %) was dipping bath, and the process variables were dipping temperature and dipping time fig. 2. the photograph of the rotating buckling test machine used in the present research. table 2, chemical compositions (wt. %) of aisi 303 stainless steel. alloy c si mn p used material a 0.114 0.5 39 1.14 0.03 2 standard (asm) [18] up to 0.15 up to 1.0 up to 2.0 up to 0.2 a: source: state company for inspection and engineering rehabilitation (sier)/baghdad. al-khwarizmi engineering journal, vol. 12 4 mechanical properties, tested in central organization for standardization and quality control (c.o.s.q.c.) / baghdad, are given in the experiments of hot dip aluminizing aisi 303 stainless steel rods are construction system of in state company for electrical industries/baghdad/ unit of casting. a high purity aluminum (99 %) was used for dipping bath, and the process variables were ng temperature and dipping time. the photograph of the rotating buckling test machine used in the present research. chemical compositions (wt. %) of aisi 303 stainless cr ni 0.03 18.20 8.19 17-19 810 source: state company for inspection and engineering rehabilitation (sier)/baghdad. table 3, experimental mechanical stainless steel used in present work (average of three specimens) aisi 303 st. st. pqrs (mpa) pt ∗ (mpa) (gpa) 880 673 204.2 * proof stress at 0.2% of stain. ** in gauge length ?# 25 vv fig. 3. schematic diagram and photograph of the hda system. 3.2. specimens types there are two types of buckling specimens used in this work, these two types are: type (1) as received specimens (non columns with circular cross 8 vv, x 201.1 vvy, different length. table (4) gives the geometrical dimensions and buckling parameters of these specimens. type (2) aluminized specimen aluminized columns with circular cross these specimens have a constant length l=440 mm, but at different hot dipping temperature (700, 740, 780, 820, and 860 o) and different dipping time (1, 2, 3, 4, and 5 minutes). table (5) gives the parameters of hot dip and buckling of these specimens. 2, no. 1, p.p. 114 (2016) properties of aisi 303 stainless steel used in present work (average of three specimens) e (gpa) elong.** % pzr (mpa) 204.2 41.4 269.2 * proof stress at 0.2% of stain. vv. schematic diagram and photograph of the there are two types of buckling specimens used in this work, these two types are: as received specimens (non-aluminized): columns with circular cross-section \ , ] 2 vv, and different length. table (4) gives the geometrical dimensions and buckling parameters of these aluminized specimens: hot-dip aluminized columns with circular cross-section. these specimens have a constant length l=440 mm, but at different hot-dip conditions from dipping temperature (700, 740, 780, 820, and and different dipping time (1, 2, 3, 4, and table (5) gives the parameters of hotdip and buckling of these specimens. ahmed naïf al-khazraji al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 114 (2016) 5 3.3. failure criterion of buckling when the maximum deflection of the column reaches the critical value of deflection (^��) of the column length, then the load measured (by pressure gauge) is the critical buckling load of the column. in the present work, the value of the critical deflection of the column is taken as (^���vv� = �? ∗ 1%� + ^#) [18, 7, and 8]. because of the rotating effect on the reading of the column deflection using a dial gauge, a laser cell circuit tool has been fabricated, with whistle sound, fixed on electronic vernier (with reading accuracy of 0.01 mm), fig. (4), to make the reading of critical deflection (̂��) more strictness. table 4, geometrical dimensions and buckling parameters of specimens type (1). no. symbol ` (mm) `a * (mm) b5 (mm) bcd ** (mm) 4a �`ad � type of *** loading type **** of column 1 1a 260 182 0.7/2 2.95 91 compression long 2b 260 182 0.78/2 3 91 combined 2 2a 280 196 0.75/2 3.18 98 compression 2b 280 196 0.9/2 3.25 98 combined 3 3a 300 210 0.76/2 3.38 105 compression 3b 300 210 0.85/2 3.43 105 combined 4 4a 320 224 0.76/2 3.58 112 compression 4b 320 224 0.69/2 3.55 112 combined 5 5a 340 238 1.48/2 4.14 119 compression 5b 340 238 0.94/2 3.87 119 combined 6 6a 360 252 0.18/2 3.69 126 compression 6b 360 252 1.35/2 4.275 126 combined 7 6a 380 266 1.43/2 4.52 133 compression 4b 380 266 1.5/2 4.55 133 combined 8 5a 400 280 1.26/2 4.63 140 compression 5b 400 280 1.38/2 4.69 140 combined 9 6a 420 294 1.45/2 4.93 147 compression 6b 420 294 1.4/2 4.9 147 combined 10 7a 440 308 1.58/2 5.19 154 compression 7b 440 308 2.0/2 5.4 154 combined 11 8a 460 322 0.6/2 4.9 161 compression 8b 460 322 2.1/2 5.65 161 combined * `a = e` ** bcd�ff� = �` ∗ k%� + b5 *** compression load= axial compression load +torsion. combined load= (axial compression + bending load (at mid span)+torsion **** 4c = g.( hpzr = ij. k , lm 4a > 4c → r5pq c5rqfp ahmed naïf al-khazraji al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 114 (2016) 6 table 5, geometrical dimensions and buckling parameters of specimens type (2). symbol no. rst �℃� sst (min) ` (mm) `a (mm) b5 (mm) bcd* (mm) 4a type of column type of loading a1 1 700 1 440 308 1.85/2 5.3 154 long compression 2 700 2 1.9/2 5.4 3 700 3 1.1/2 5 4 700 4 2.1/2 5.5 5 700 5 1.4/2 5.1 b1 6 740 1 440 308 1.95/2 5.4 154 long compression 7 740 2 2.52/2 5.7 8 740 3 0.18/2 4.5 9 740 4 0.76/2 4.8 10 740 5 1.5/2 5.2 c1 11 780 1 440 308 1.5/2 5.3 154 long compression 12 780 2 1.92/2 5.4 13 780 3 1.45/2 5 14 780 4 1.7/2 5.3 15 780 5 2.15/2 5.5 d1 16 820 1 440 308 2.5/2 5.7 154 long compression 17 820 2 1/2 4.9 18 820 3 1/2 4.9 19 820 4 1.7/2 5.3 20 820 5 1.8/2 5.3 e1 21 860 1 440 308 1.1/2 5 154 long compression 22 860 2 2.3/2 5.6 23 860 3 1.45/2 5 24 860 4 0.6/2 4.7 25 860 5 2.7/2 5.8 a2 26 700 1 440 308 2.12/2 5.3 154 long combined 27 700 2 0.45/2 5.4 28 700 3 1.25/2 5 29 700 4 1.9/2 5.5 30 700 5 1.8/2 5.1 b2 31 740 1 440 308 1.6/2 5.4 154 long combined 32 740 2 2.27/2 5.7 33 740 3 0.6/2 4.5 34 740 4 1.1/2 4.8 35 740 5 1.75/2 5.2 c2 36 780 1 440 308 1.9/2 5.3 154 long combined 37 780 2 1.8/2 5.4 38 780 3 1.95/2 5 39 780 4 1.95/2 5.3 40 780 5 1.78/2 5.5 d2 41 820 1 440 308 2.9/2 5.7 154 long combined 42 820 2 2.15/2 4.9 43 820 3 1.4/2 4.9 44 820 4 1.23/2 5.3 ahmed naïf al-khazraji 45 820 5 e2 46 860 1 47 860 2 48 860 3 49 860 4 50 860 5 * ^���vv� = �? ∗ 1%� � fig. 4. system used to control the deflection of columns during buckling test. 4. results and discussion table (6) shows the experimental results of dynamic buckling test of 303 aisi column specimens without aluminizing (type 1). (6) it can be observed that the critical buckling stress (���) decreased with increasing in effective slenderness ratio (�&) for both dynamic compression load (compression-torsion dynamic combined load (compression torsion load). also it can be seen that the bending load (�u&v.) is greater than the critical buckling stress for all slenderness ratio, but is al decreased with increased in �&. in order to make a comparison between the experimental results and theoretical results, eq. (1) is used to calculate the theoretical critical buckling stress for the specimens of type (1). the results of eq. (1) and eq. (2) are shown in table (7). from table (6) and table (7), it can be observed that the experimental critical stress (�&w.) is, in general, lower than the value of theoretical critical stress (���) from perry robertson interaction formula. the difference between the experimentally and theoretically results (perry robertson critical buckling stress) is duo to: initial imperfection of columns, the accuracy of construction of test machine, the alignment of loads, and the details of support condition which are not perfect as al-khwarizmi engineering journal, vol. 12 7 1.57/2 5.3 440 308 0.9/2 5 154 long 1.55/2 5.6 2.6/2 5 2.2/2 4.7 2.25/2 5.8 � � ^# system used to control the deflection of columns during buckling test. experimental results of dynamic buckling test of 303 aisi column specimens without aluminizing (type 1). in table (6) it can be observed that the critical buckling ) decreased with increasing in effective r both dynamic torsion load) and dynamic combined load (compression-bendingload). also it can be seen that the bending ) is greater than the critical buckling stress for all slenderness ratio, but is also . in order to make a comparison between the experimental results and theoretical results, eq. (1) is used to calculate the theoretical critical buckling stress for the specimens of type (1). the results of eq. (1) and (2) are shown in table (7). from table (6) and table (7), it can be observed that the ) is, in general, lower than the value of theoretical critical stress ) from perry robertson interaction formula. ence between the experimentally and theoretically results (perry robertson critical buckling stress) is duo to: initial imperfection of the accuracy of construction of test the alignment of loads, and the details of h are not perfect as assumed in theoretical consideration. formula (eq. 8) is used to fit the experimental results of the specimen’s mathematical model that describes the buckling behavior of these specimens. table ( values of k function that used to determine the fitted model, fig. (5). the fitted model was in the form of k = 1/(-3.48777 + 3.40067/p the values of the predicated buckling load (p) are given in table (9). the fitted model gives a good correlation between the experimental values and theoretical values for slenderness ratio (91 with maximum error of 5.757 % shows the experimentally results of dynamic buckling test of specimens type (2) (hot aluminized long columns) with constant slenderness ratio of �& dip conditions (dipping temperature and dipping time). from table (10), it can be detected that there is enhancement in buckling resistance of long aluminized columns compression load (compression and torsion) and combined load (compression, bending, and torsion), but the results are approximately the same. whatever, it appear that the aluminizing conditions at dipping time of ( dipping temperature of ( maximum enhancement of dynamic buckling resistance for the specimens of type (2). in order 2, no. 1, p.p. 114 (2016) combined system used to control the deflection of columns during buckling test. assumed in theoretical consideration. greenhill ) is used to fit the experimental specimen’s type (1) to find a mathematical model that describes the buckling behavior of these specimens. table (8) shows the values of k function that used to determine the the fitted model was in the 3.48777 + 3.40067/pexp/��� � ) and the values of the predicated buckling load (p) are fitted model gives a good correlation between the experimental values and theoretical values for slenderness ratio (91-154) with maximum error of 5.757 %. table (10) shows the experimentally results of dynamic buckling test of specimens type (2) (hot-dip aluminized long columns) with constant 154 and different hotdip conditions (dipping temperature and dipping ), it can be detected that there is enhancement in buckling resistance of long aluminized columns under both dynamic compression load (compression and torsion) and combined load (compression, bending, and torsion), but the results are approximately the same. whatever, it appear that the aluminizing conditions at dipping time of (���=3 min) and ng temperature of (���=820o) gives a maximum enhancement of dynamic buckling resistance for the specimens of type (2). in order ahmed naïf al-khazraji al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 114 (2016) 8 to show the improvement of dynamic buckling resistance of aluminized columns (type 2) compared with non-aluminized columns (type 1), fig.(6) is plotted by using the experimental results of table (6) for specimens type (1), and table (10) for specimens type (2), whereas table (7) gives the theoretical results from perry robertson interaction formula. the improvement, based on the average value of critical buckling stress, is as follow: (64.8 %) for long columns type (2), compared with columns type (1), under dynamic compression loading, and (56.6 %) for long columns type (2), compared with columns type (1), under dynamic combined loading, and (38.3 %) for long columns type (2) compared with perry robertson critical buckling stress. these enhancement ratios of buckling resistance are calculated by compared the values of critical buckling stress illustrated in fig. (7). it should be noted that the effect of rotating of the column (torsional loading) during the applied of compression load and/or compression-bending loads was appear clearly first by a spatial (nonplanar) shape of column deformation until buckling is occur and second by reduced the value of the critical buckling load. the lateral loading (bending load) on rotating columns leads to a fast increasing in the lateral deflection of the column under combined loading conditions and a signification reduction in axial compressive load and as a result decrease the buckling resistance of the columns compared with the case without lateral loading . it experimentally noted that the effect of the lateral loading on the buckling resistance was much greater than the effect of the twisting or torsional loading for the same slenderness ratios. table 6, experimental results of dynamic buckling test of column specimen type (1). no. symbol xayz �z� payz �{z|� }~ap. �z� p~ap. �{z|� 1 1a 7422.0126 147.6563 ---- 1b 4523.893 90 306 247.312 2 2a 6785.8401 135 ---- 2b 4241.15 84.375 285.6 248.58 3 3a 6008.296 119.5313 ---- 3b 3887.721 77.3438 265.2 247.312 4 4a 5301.4376 105.4688 ---- 4b 3534.292 70.3125 244.8 243.507 5 5a 4948.0084 98.4375 ---- 5b 3322.234 66.0938 224.4 237.166 6 6a 4665.2651 92.8125 ---- 6b 3180.863 63.2813 204 228.288 7 7a 4241.1501 84.375 ---- 7b 3039.491 60.4688 183.6 216.874 8 8a 3887.7209 77.34375 ---- 8b 2827.433 56.25 163.2 202.923 9 9a 3534.2917 70.3125 ---- 9b 2686.062 53.4375 142.8 186.435 10 10a 3180.8626 63.28125 ---- 10b 2474.004 49.2188 122.4 167.411 11 11a 2827.4334 56.25 ---- 11b 2120.575 42.1875 81.6 116.68 ahmed naïf al-khazraji al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 114 (2016) 9 table 7, theoretical values of critical load and critical stress using perry robertson interaction formula for specimen type (1). table 8, theoretical values of greenhill formula for specimen type (1). * for motor power of 0.5 kw and n=17 r.p.m fig. 5. function k predicated using greenhill formula results. no. ` (mm) `a (mm) 4a�`ad � xcd �z� pcd �{z|� 1 260 182 91 9764.33 194.2552 2 280 196 98 8602.489 171.1411 3 300 210 105 7625.835 151.7112 4 320 224 112 6800.153 135.2848 5 340 238 119 6097.662 121.3091 6 360 252 126 5496.088 109.3412 7 380 266 133 4977.642 99.02704 8 400 280 140 4528.094 90.08358 9 420 294 147 4136.02 82.28352 10 440 308 154 3792.199 75.44341 11 460 322 161 3489.142356 69.41429 no. ` (mm) `a (mm) 4a �`ad � xayz �z� xcd� �n��n��n��n� xayz/xcd� {s* (n.mm) k 1 260 182 91 7422.012644 12233.2698 0.606707182 209523 0.471332517 2 280 196 98 6785.840132 10548.07447 0.643325012 209523 0.533008048 3 300 210 105 6008.29595 9188.544868 0.65388982 209523 0.579730475 4 320 224 112 5301.437603 8075.869513 0.656454094 209523 0.620682717 5 340 238 119 4948.00843 7153.711403 0.691670121 209523 0.696118496 6 360 252 126 4665.265091 6380.933936 0.731125747 209523 0.789296097 7 380 266 133 4241.150083 5726.932397 0.740562275 209523 0.848162555 8 400 280 140 3887.720909 5168.556489 0.752186983 209523 0.913503038 9 420 294 147 3534.291735 4688.033096 0.753896498 209523 0.962503809 10 440 308 154 3180.862562 4271.534288 0.744665113 209523 0.989941795 11 460 322 161 2827.433388 3908.171258 0.723467116 209523 0.994481029 ahmed naïf al-khazraji al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 114 (2016) 10 table 9, theoretical results of fitted model (k = 1/(-3.48777 + 3.40067/pexp/���� )). table 10, experimental results of dynamic buckling test of column specimen type (2). symbol no. xayz �z� payz �{z|� symbol no. xayz �z� payz �{z|� }~ �z� p~a �{z|� a1 1 5655 112.5 a2 26 3534.292 70.3125 163.2 357.1437 2 6362 126.5625 27 3534.292 70.3125 204 446.4297 3 5655 112.5 28 3534.292 70.3125 183.6 401.7867 4 4948 98.4375 29 4241.15 84.375 163.2 357.1437 5 4948 98.4375 30 4241.15 84.375 204 446.4297 b1 6 4948 98.4375 b2 31 3534.292 70.3125 204 446.4297 7 4241 84.375 32 3534.292 70.3125 183.6 401.7867 8 4948 98.4375 33 4241.15 84.375 183.6 401.7867 9 5655 112.5 34 4241.15 84.375 204 446.4297 10 5655 112.5 35 3534.292 70.3125 163.2 357.1437 c1 11 4948 98.4375 c2 36 4241.15 84.375 204 446.4297 12 5301 105.4688 37 3534.292 70.3125 183.6 401.7867 13 5655 112.5 38 4241.15 84.375 183.6 401.7867 14 5301 105.4688 39 2827.433 56.25 163.2 357.1437 15 4948 98.4375 40 2827.433 56.25 204 446.4297 d1 16 5655 112.5 d2 41 4241.15 84.375 183.6 401.7867 17 7069 140.625 42 4241.15 84.375 204 446.4297 18 4948 98.4375 43 4948.008 98.4375 183.6 401.7867 19 4948 98.4375 44 4241.15 84.375 204 446.4297 20 5301 105.4688 45 4241.15 84.375 204 446.4297 e1 21 5655 112.5 e2 46 4241.15 84.375 204 446.4297 no. ` (mm) `a (mm) k ���� (n.mm) x (fitted model) �z� xayz �z� error% 1 260 182 0.472287209 334774.5823 7441.032476 7422.012644 0.296 2 280 196 0.556076439 366012.6571 7091.215227 6785.840132 4.500 3 300 210 0.583802725 358644.7718 6052.238726 6008.29595 0.731 4 320 224 0.590809751 340265.0296 5013.515634 5301.437603 -5.431 5 340 238 0.699870006 379365.7378 4971.40402 4948.00843 0.472 6 360 252 0.859468903 439994.5612 4933.861242 4665.265091 5.757 7 380 266 0.905599535 439210.0157 4423.530637 4241.150083 4.300 8 400 280 0.967798059 445907.1091 4027.305436 3887.720909 3.590 9 420 294 0.977496457 428929.1311 3569.315935 3534.291735 0.990 10 440 308 0.926835156 388212.4536 3027.175305 3180.862562 -4.831 11 460 322 0.824573802 330362.9546 2336.029801 2827.433388 -17.3798 ahmed naïf al-khazraji 22 4948 98.4375 23 4948 98.4375 24 4241 84.375 25 4241 84.375 fig. 6. critical stressslenderness ratio relation for stainless steel 303 aisi columns under dynamic compression and combined loads compared with theoretical results (perry robertson formula). fig. 7. critical buckling stress for the specimens of type (1) and type (2) at the same effective slenderness ratio. 5. conclusions 1. the experimental values of the critical buckling loads and/or stresses for non aluminized long columns, (�& > �� , �&�91 �� 161��, are less than the theoretical values predicated by perry robertson interaction formula , and this differences in results is duo to effect of initial imperfection of columns, the accuracy of al-khwarizmi engineering journal, vol. 12 11 47 4241.15 84.375 183.6 48 4241.15 84.375 204 49 3534.292 70.3125 163.2 50 2827.433 56.25 204 slenderness ratio relation for stainless steel 303 aisi columns under dynamic compression and combined loads compared with formula). critical buckling stress for the specimens of type (1) and type (2) at the same effective the experimental values of the critical buckling loads and/or stresses for nonaluminized long columns, , are less than the theoretical values predicated by perry robertson interaction formula , and this differences in results is duo to effect of initial the accuracy of construction of test machine, loads, and the details of support condition. 2. using of hotdip aluminizing surface treatment has make double benefit one of them is to develop protection layer for substrate material from environment conditions and the other is the improvement of dynamic buc resistance of long aluminized columns under dynamic compression loading and under dynamic combined loading. 3. the improvement in the dynamic buckling resistance were (64.8 %) for long columns type (2), compared with columns type (1), under dynamic compression loading only, and ( %) for long columns type (2), columns type (1), under dynamic combined loading, and (33.3 %) for long columns type (2) compared with perry robertson critical buckling stress. 4. the optimum hot-dip aluminizing co that give a maximum enhancement of dynamic buckling resistance for the specimens of type (2), are: dipping time of ( dipping temperature of ( 5. torsional loading during the applied of compression load and/or compression loads was appear clearly first by a spatial (non-planar) shape of column deformation until buckling is occur and second by reduced the value of the critical buckling load. 6. the lateral loading (bending load) on rotating columns leads to a fast increas deflection of the column under combined loading conditions and a signification reduction in axial compressive load (critical buckling load). 2, no. 1, p.p. 114 (2016) 401.7867 446.4297 357.1437 446.4297 construction of test machine, the alignment of ads, and the details of support condition. dip aluminizing surface treatment has make double benefit one of them develop protection layer for substrate material from environment conditions and the other is the improvement of dynamic buckling resistance of long aluminized columns under dynamic compression loading and under dynamic combined loading. the improvement in the dynamic buckling (64.8 %) for long columns type (2), compared with columns type (1), under pression loading only, and (56.6 %) for long columns type (2), compared with under dynamic combined loading, and (33.3 %) for long columns type (2) compared with perry robertson critical dip aluminizing conditions, a maximum enhancement of dynamic buckling resistance for the specimens of type (2), are: dipping time of (t��=3 min) and dipping temperature of (t��=820o). during the applied of compression load and/or compression-bending loads was appear clearly first by a spatial planar) shape of column deformation until buckling is occur and second by reduced the value of the critical buckling load. the lateral loading (bending load) on rotating columns leads to a fast increasing in the lateral deflection of the column under combined loading conditions and a signification reduction in axial compressive load (critical ahmed naïf al-khazraji al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 114 (2016) 12 notation ℃ dipping temperature ��� s (second) dipping time t�� n (newton) theoretical and experimental critical buckling load p��, p��� ��m the cross-sectional area of the column a ��� modulus of elasticity e dimensio nless effective length factor(depends on column ends support) k mm unsupported and effective length of the column l, l� �� smallest radius of gyration of the column r ��� moment of inertia of the column cross sectional area i � critical load for buckling without torque (euler formula) ��� � �.�� applied torque 67 �.�� critical torque for buckling without axial force 6�� � � bending load f� greek letters ��� theoretical and experimental critical buckling stress pcd, payz dimension less the reduction factor accounting for buckling ��� the yield strength �� dimension less the imperfection factor defined in table (3-1). " dimension less the limiting and non-dimensional slenderness ratio �# , � dimension less effective and critical slenderness ratio �& , �� ��� ultimate and proportional limit of column’s material � /7, �./ �� initial and critical deflection of the column ^# , ^�� ��� bending stress= f�/a �u 6. references [1] t. h. g. megson,”structural and stress analysis”, butterworth-heinemann, 2000. [2] jianqiao ye,” structural and stress analysis theories, tutorials and examples”, taylor & francis, 2008. [3] r. c. hibbeler, si conversion by s. c. fan,” statics and mechanics of materials”, prentice-hall, inc., 2004. [4] n. r. baddoo,” a comparison of structural stainless steel design standards”, the steel construction institute, p.p. 131-149, (2003). [5] l. gardner and d. a. nethercot, “experiments on stainless steel hollow sections-part 2: member behaviour of coloumns and beams”, journal of constructional steel research, vol. 60, p.p. 1319-1332, (2004). [6] kifah hameed al-jubori, “columns lateral buckling under combined dynamic loading”, phd. thesis, university of technology, department of technical education, 2005. [7] hamed ali hussein,”buckling of square columns under cycling loads for nitriding steel din (ck45, ck67, ck101)”, phd. thesis, university of technology, department of mechanical engineering, 2010. [8] al-alkhawi h. j. m., al-khazraji a. n., and essam zuhier fadhel, “determination the optimum shot peening time for improving the buckling behavior of medium carbon steel”, eng. & tech. journal, vol. 32, part (a), no. 3, 2014. [9] sung-ha hwang, jin-hwa song, and yongsuk kim, “effects of carbon content of carbon steel on its dissolution into a molten aluminum alloy”, materials science and engineering a 390, pp. 437–443, 2005. ahmed naïf al-khazraji al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 114 (2016) 13 [10] hishamuddin hj. husain, muhamad daud, anasyida abu seman and abdul razak daud, “preliminary study on metallic coating of steel substrates through hot dip aluminizing by using energy dispersive x-ray spectroscopy (edx) technique”, journal of nuclear and related technologies, vol. 6, no. 2,pp. 63-69, december, 2009. [11] rajab mohammed hussein, “improvement of stainless steel (316l) hot corrosion and oxidation resistance by aluminizingsiliconizing”, phd. thesis, university of technology, department of production engineering and metalluragy, 2007. [12] g. h. awan, f. ahmed, l. ali, m. s. shuja, and f. hasan, “effect of coating thickness on the formability of hot dip aluminized steel”, pak. j. engg. & appl. sci., vol. 2, p.p. 14-21, jan 2008. [13] n. r. baddoo and b. a. burgan, “structural design of stainless steel”, the steel construction institute, sci publication p291 2001, 2001. [14] euro inox and the steel construction institute, “structural design of stainless steel”, 3rd edition, 2006. [15] l. gardner and d. a. nethercot, “designers’ guide to en 1993-1-1. eurocode 3: design of steel structures. general rules and rules for building”, the steel construction institute, thomas telford ltd., 2005. [16] james m. gere, “mechanics of materials”, 6th ed, thomson learning, inc., 2004. [17] zdeněk p. bažant and luigi cipolin”stability of structures elastic, inelastic, fracture, and damage theories”, dover puplications, inc., 2003. [18] asm handbook,”surface engineering”, asm international, vol. 5, 1994. ا���ر�� �� �� 1، ا�� د12 ��� ا���ارزم� ا��� ��� ا����ما���� ،14 -1 )2016( 14 �.�& م$�وم� ا-�,��ج �*(� ة ا�'� �� م& ا�!�% ا��$�وم ��! أ /aisi 303 ����0ا�� )4'2 $� ا�2�3 ا�.�1& hda( ا���ر���� ���5 ��24 ا���(�� **���2 (�� ا����42 *ا�����*** *،** �����������'&�� / %$# ا�"! �� ا'!�(� .اد/ ا�+�*(� ا �( ات * **����12 وا� .اد/ ا�+�*(� ا�)6!�� ا�'�45 / *(" ا�)�!3'&�� / %$# ا dr_ahmed53 @yahoo.com78و�(��: ا�;8: ا9 * alrabiee202@yahoo.com :8;�: ا9��)8و�7 ا ** hameedshamkhi@yahoo.com : ا��� رو�� ا��ر�د*** ا��*�� <3���6وم ��>!'?� *1 ا�>3< ا��!� ا�@���!� و8�a ا�@��� ة ا�5':�3 ا?c� 7��*�!: ��$3'ك ا�9;(�ج ا 73�)�. aisi 303أ 7k #l ھiا ا�;hg ا�)f6g ا ،7��*�!: ��n ا�9;(�ج اo8�p�l qgl ة ��!� q<gk h�o٢٢ ھiه ا9?�@* 8�a �!�? )type 1 ( 1 ٥٠وv�$��8 ا-��!� .�6:85 ا�@* �!�? )type 2( ، ��w اix7 و��*�!: ��n اz�9-�ط اo ���g��8، .^�)[ ام *�gk �!x\ ا�9;(�ج ا� وار و-��8 وز*1 ا-��8 *[)3`� *1 در&� 8oارة اa 8وفb.و >x8���n اg �n ا�g!�ء(o 2ط زا�-zا� n�o .( �-�d e* f2�(!��-8ض lgreenhill# ا�)[ ام lperry robertson interaction formula . �-�d# *�6ر�� ا 7��*�!: ��n ا�9;(�ج اo 8�p^l qgl 3'ك ا�9;(�ج� h<: 7i�:ر n:ل ?43 *'د'<g��8 أ. ا-��. �!�����3 ا9? �66 *1g(�����3 ا)�ظ"8ت ا�!)�f2 ا�`�2 ة ا ����*�!: ���ل اo98 ا�p^l qgl 3'ك ا�9;(�ج�1 ?43 v�$��$)[ *� 7k ھiا l. ا�� ة ا�5':�3 ا?c� 7��*�!: ��nl ھiا ا�)^8�p اg(. 7.�+:9$�1 *�6و*� ا�9;(�ج ا 73: ��x >$!��)'�m ا&"�د ا�9;(�ج ا�8gج، وھiه ا� �:'n* >$!. hg;�� ة ا�5':�3 �'ع) % 64.8( :ا?c�و8�p^l qgl ) ١(*�6ر�� .�9?� ة �'ع ) ٢( ،7��*�!: ���n اz�9-�ط7 اg(�� ة ا�5':�3 �'ع ) % 56.6(و ا?c��x8<، و ) ١(*�6ر�� .�9?� ة �'ع ) ٢(���n ا� :!�*��7 اg(�) %33.3(و8�p^l qgl ا � ة �'ع ?c�)٢ (�-�d 1* ب'$g�� .perry robertson *�6ر�� .�6�� ا&"�د ا�9;(�ج ا�8gج ا 36-44 al-khwarizmi engineering journal,vol. 12, no. 1, p.p. multi-dimensional angle of arrival estimation by circular phased adaptive department of (received abstract in this paper the use of a circular constrained minimum variance beam arrival (aoa) estimation in 2-d as we 3-d estimation), rather than interference can compared with the modified multiple signal classification ( system has exhibited astonishing results for equivalent to the music technique (for for sources which are under the estimation finally, the proposed system needs le eigen value decomposition techniques active detecting means such as radars. keywords: angle of arrival estimation, 1. introduction over the last decade, the aoa estimation or guesstimate the direction and location of the transmitting sources is the most desirable activities used in electronic ware-fare and security activities [1-4]. the aoa estimations of the received signals by anarray antennas has gained a great attention in the array signal processing subject such as radar and wireless communication system [5]. most of new directions finding techniques such as multiple signal classification (music), estimation of signal parameter via rotational invariance (esprit) and others [6] had studied in contexts of one dimensional 1 (azimuth angle) cases. these techniques are based on eigen value decomposition of the covariance matrix to the sampled input ��� these techniques need intensive computa process so that they might not be suited for real khwarizmi engineering journal,vol. 12, no. 1, p.p. 3644 (2016) dimensional angle of arrival estimation by circular phased adaptive array antennas bassim sayed mohammed department of electrical engineering /university of technology email:bassim_sayed@yahoo.com (received 16 february 2015; accepted 12 november 2015) the use of a circular array antenna with adaptive system in conjunction with forming (lcmvb) algorithm is proposed to meet the requirement of angle d as well as the signal to noise ratio (snr) of estimated sources (three dimensional rather than interference cancelation as it is used for. the proposed system was simulated, tested and multiple signal classification (music) technique for 2-d estimation. the results system has exhibited astonishing results for simultaneously estimating 3-d parameters with accuracy equivalent to the music technique (for estimating elevation and azimuth angles), and it has privilege for sources which are under the estimation process. needs less computational time and hardware complexity when it is used by music technique. also, it has cost effectiveness with respect to (3 , music, adaptive array antenna system. over the last decade, the aoa estimation or guesstimate the direction and location of the most desirable fare and security the aoa estimations of the received signals a great attention in ject such as radar tem [5]. most of ing techniques such as classification (music), via rotational nce (esprit) and others [6] had been contexts of one dimensional 1-d . these techniques are based eigen value decomposition of the covariance of the array. these techniques need intensive computation not be suited for real time application (where the required be trucked on line). one dimension is suffic aoa for the land and sea transmit assuming that the elevation angle is very s for airborne transmitting estimation of these sources needs a two dimensional (2-d) real time estimator (elevation θ and azimuth φ). adaptive array antenna with fast algorithm and less compu offers an effective passive mean active means (like radars elevation and azimuth of the these transmitting sources. this use is very important in a real war environment because it is a passive and secured activity from the point of view of the electronic ware fare missions(reconnaissance activity). unlike the active systems(radar detected and jammed by electronic al-khwarizmi engineering journal (2016) dimensional angle of arrival estimation by circular phased array antenna with adaptive system in conjunction with modified linearly ) algorithm is proposed to meet the requirement of angle of of estimated sources (three dimensional celation as it is used for. the proposed system was simulated, tested and d estimation. the results show the d parameters with accuracy approximately estimating elevation and azimuth angles), and it has privilege to estimate snr computational time and hardware complexity when it is compared with has cost effectiveness with respect to (3-d) where the required signals are to one dimension is sufficient for estimating land and sea transmitting sources, elevation angle is very small. for airborne transmitting means, the aoa sources needs a two d) real time estimator (elevation adaptive array antenna with fast convergence algorithm and less computational time process effective passive means tool rather than (like radars) to estimate the elevation and azimuth of the platform that carried these transmitting sources. this use is very important in a real war because it is a passive and secured of view of the electronic reconnaissance activity). unlike the active systems(radars) which can be detected and jammed by electronic means or bassim sayed mohammed destroyed by weapons. the adaptive array antenna is mainly used for suppressing the interference, multipath and jammer signals, while researches talks about the ability of using adaptive array antenna system as angle of arrival estimator [7]. most of the previous researchers use of linear array antenna to estimate angles only. simultaneous (2-d) estimation n to use a circular array antenna. figure (1) shows a circular array antenna mounted on x parallel to the z-y plane with elevation angle θϵ[0,/2π] and azimuth angle covariance matrix rxx of the received signals now carrying complete information elevation and azimuth angles as well as the levels of the received signals. we can information in conjunction with the adaptive processors and algorithms to simultaneously extract the (elevation θ, azimuth φ snr). fig. 1. uniformly circular array 2. two-dimension mathematical formulation the uniform circular array (uca) geometry is shown in figure (1), the antenna element assumed to be identical, omnidirectional, and uniformly distributed over a circumference of a circle of radius r in the x-y plane. a spherical coordination system is used to represent the angle of arrival of the incoming plane wave, the origin of the coordination system located at the array. source elevation angles �� �0, � up from y-axis toward the z-axis and the azimuth angles�� 0,2�� are measured from x the y-axis, the elements n of the array is displaced by an angle of [6] �� � � � ��� � � 1,2, … ,�and the radius r will be r=n*d*λ/2π al-khwarizmi engineering journal, vol. 12, no. 37 destroyed by weapons. the adaptive array antenna suppressing the interference, signals, while very few of using adaptive arrival estimator previous researchers discuss the use of linear array antenna to estimate azimuth estimation needs to use a circular array antenna. figure (1) shows a circular array antenna mounted on x-y plane and y plane with elevation angle azimuth angle φϵ[0,2π]. a the received signals is w carrying complete information about the d azimuth angles as well as the input can explore this on with the adaptive s to simultaneously as well as the uniformly circular array system. matical the uniform circular array (uca) geometry 1), the antenna elements directional, and uniformly distributed over a circumference of a y plane. a spherical tem is used to represent the angle of the incoming plane wave, the origin of the coordination system located at the center of � are measured axis and the azimuth are measured from x-axis toward axis, the elements n of the array is displaced and the radius … (1) where d is the inter element spacing and wave length of the operating frequency. for k snapshot the received signal vector ���, �, �� � ∑ ������, � �!" where ������, �, �� , ���� signal and the thermal noise vectors of a lengt (1×n) respectively. d is the numb signals under angle of arrival if the received signal is incident from elevation angle � and azimuth � vector is given by [8] #��, �, �� � $ %&�'°)*+,� where a is signal amplitude, � is arbitrary carrier phase angle distributed [0 2�] and uis the array vector corresponding to the incident angles of the received signals and defined by [8] � �./��, �� 0%& 12 3 ∗5∗678 where ./��, �� is the element field patt t is denotes to the vector transpose. the thermal noise vol channels are assumed to be mutually uncorrelated random signals with zero mean and and it can be expressed as #���� � #"���, # , … #� the adapted array output of figure by multiplication of the received signals with the adapted weight vector [w]and it can be expressed as 9��� � ∑ :���� �!" and in the vector form ;��� � <*# � #*< where w and x vectors are given by < � :", : , … . , :��* # � �", � , …… , ���* signal and noise in the adaptive array antenna system may be described in the terms of statistics properties, so this make possible to evaluate the system by its statistical average where e[.] is the expected value of any random signal, the evaluation of st directly to interested quantities related to the second statistical moment such as covariance matrix, which is closely related to correlation matrix for stationary signals. , no. 1, p.p. 3644 (2016) where d is the inter element spacing and λ is the wave length of the operating frequency. for k snapshot the received signal vector will be � �, �� > �������� … (2) �� are the ith received signal and the thermal noise vectors of a length d is the number of received signals under angle of arrival estimation process. if the received signal is incident from elevation �, then received signal � … (3) where a is signal amplitude, :° center frequency, is arbitrary carrier phase angle distributed [0, uis the array vector corresponding to the incident angles of the received signals and defined 678�?� @a6�bc,d�e� * … (4) is the element field pattern and t is denotes to the vector transpose. the thermal noise voltages in the array channels are assumed to be mutually uncorrelated with zero mean and f variance be expressed as [7] �����* …(5) the adapted array output of figure.2 is performed the received signals with the [w]and it can be expressed … (6) … (7) where w and x vectors are given by … (8) … (9) signal and noise in the adaptive array antenna system may be described in the terms of the statistics properties, so this make possible to evaluate the system by its statistical averageg ∙�, [.] is the expected value of any random ation of statistical average leads to interested quantities related to the second statistical moment such as covariance matrix, which is closely related to correlation matrix for stationary signals. bassim sayed mohammed fig. 2. adaptive array antenna model the covariance correlation matrix of received signals vector is defined as [6] ijj � g k∗k*� � k∗k*�lllllllll where ijj is � m � autocorrelation matrix of received signal and it is hermitian (i.e. noo∗ p ). 3. two dimensional (2d) music estimator the music technique is a simple, popular, high resolution and efficient eigen structure method for angle of arrival estimation. in order to estimate ��, �� by music, a circular array antenna system is used. the music spatial spectrumfor��, �� is given by [6] tu��, φ� � " wx�?,y� zdzd[w∗�?,b� where w��, �� is a spatial vector given by w��, �� � �.\��, ��%c&]∗ 12 3 ∗5∗^��?∗ ��� _ � 1,2… � and .]��, ��is the z pattern. z� is a noise subspace composed from (n-d) eigen vector associated with the channel thermal noise components 4. mathematical model for proposed estimator a circular array antenna with radius r in the x y plane is used in conjunction with the linearly constrained minimum variance beam forming (lcmvb) algorithm as a proposed system to estimate elevation angle ��� and azimuth ��� of received signals as well as signal to noise ratio (snr) (i.e.3-d estimation). the adaptive array output of figure expressed as[8]. al-khwarizmi engineering journal, vol. 12, no. 38 adaptive array antenna model. the covariance correlation matrix of received … (10) autocorrelation matrix of signal and it is hermitian (i.e.noo � (2d) music is a simple, popular, t eigen structure estimation. in order to by music, a circular array antenna system is used. the music spatial … (11) is a spatial vector given by `a^�yc,b�� * … (12) is the zth element is a noise subspace set matrix d) eigen vector associated components. proposed 3-d a circular array antenna with radius r in the xy plane is used in conjunction with the linearly imum variance beam forming (lcmvb) algorithm as a proposed system to and azimuth angle as well as signal to noise ure. (2) can be g|9��, �, ��| � g|d*k∗ � d*ijj��, �, ��d∗ it is required to minimized the array output power according to the following cost function given by ef�'d*ijj��, �, φ�d∗ subjected tow*d � wgd where (t)is the transpose notation, complex conjugateand dagger conjugate notation [*]t. finding dahi��, �� to satisfy eq. (14) and eq. (15) can be accomplished by the method of lagrange multipliers. adjoining the constraint eq. (15) to eq. (14) performs the the minimization of this function is giving by ef�'∗j�d,d∗� � d*i > λ ld the gradient of eq. (16) with respect to to mn∗j�d,d∗� � ijj�o, � the minimum value of eq. (17 ijj��, �, ��dahix > w∗�� therefore the optimal weight dahip ��, �� � pijjc"��, � so the lagrange multipliers evaluated from the constraint given by eq. (15 w*��, ��dahi��, �� � 1 w*��, �� pijjc"�o, �, ��w it then follows that λ is given by λ�θ, φ� �– w*��, ��ijjc"� combining eq. (19) and eq. (21) then yields to the optimum constrained weight vector dahi��, �� � isstu�o,?, wv�?,b�isstu� if dahi ��, ��is substituted output of the array system optimum when the azimuth angle elevation angle ���of constrain coincide with the azimuth and elevation of any , no. 1, p.p. 3644 (2016) ∗��, �, ��| … (13) it is required to minimized the array output power according to the following cost function … (14) d∗ � 1 … (15) is the transpose notation, (*) is a dagger ( † ) is a transpose to satisfy eq. (14) and eq. (15) can be accomplished by the method of lagrange multipliers. adjoining the constraint eq. (15) to eq. (14) performs the cost function. the minimization of this function is giving by ijj��, �, ��x∗ ldgw∗��, �� p 1y� … (16) ) with respect tod∗ leads �, ��dz > w∗��, ��λ … (17) the minimum value of eq. (17) is given by �, ��λ � 0 … (18) therefore the optimal weight vector is � , ��w∗��, ��λ … (19) grange multipliers λ may now be om the constraint given by eq. (15). �w∗�θ,φ�λ� � 1 … (20) λ is given by �o, �, ��w∗��, ���c" … (21) combining eq. (19) and eq. (21) then yields to the optimum constrained weight vector � ,b�w∗�?,b� �o,?,b�w∗�?,b�� … (22) is substituted into eq. (3), the output of the array system 9��, ��will be when the azimuth angle ��� and constrain vector w��, �� is coincide with the azimuth and elevation of any bassim sayed mohammed al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 3644 (2016) 39 0 10 20 30 40 50 60 70 80 90 0 5 10 15 20 25 30 35 estimated elevation-angle of arrival (degree) o ut pu t s n r l ev el x: 60 y: 31.01 x: 45 y: 30.99 theta =45. deg. snr=14.91 db theta =60. deg. snr=14.92 received signals in the range of �� �0, �, and�� 0,2��and it can be expressed as y��, �, �� = dahi* ��, ��k��, �, �� … (23) it can be seen from eq. (22) that for each received signals we have an optimum weight vector dahi ��, �� related to the incident angles of these signals. this weight vector is updated (i.e. changes its value) according to the received environments. 5. signal to noise ratio snr(|,}) estimation since we calculate the optimum weight vector dahi ��, �� according to eq. (22), this weight vector maximized the output of the array in the direction of received signals according to the constraint condition eq. (15). so the output voltage of the proposed array system due to ith received signal is 9���, �, �� and due to the nthchannel thermal noise voltage is 9���� and they can be expressed as 9���, �, �� = d*��, ��k���, �, �� … (24) 9���� = d*��, ��k���� … (25) then the output powers for signals and noise can be written as g|9���, �, ��| = |d*��, ��k�∗��, �, ��| = d*��, ��i����, �, ��d∗��, �� … (26) where ~����, �, �� is a covariance matrix of ith received signal under angle of arrival estimation and it is equal to ~����, �, �� = k�∗���, �, �� ∗ k�*��, �, �� … (27) similarly the out power due to thermal noise is g|9����| = |d*��, ��k���, �, ��| = d*��, ��i��d∗��, �� … (28) i�� = �� �, where �� is the second moment of noise signals (noise power) and � is an identity matrix of dimensions (n×n). i��is diagonal matrix due to thermal noise voltages in the channels, they are uncorrelated signals (random signals). now the output snr��, ��which can be estimated to each received signal to perform (3-d) estimation (i.e. elevation, azimuth and snr estimation) is equal to ��~��, �� = /|����),?,b�|1 /|�d�)�|1 = d�����?,b�i���),?,b�d����),?,b� d�����),?,b�iddd����),?,b� …(29) 6. simulation results all simulation programs were written in matlab 7.10 and the following assumption are considered: a) the number of array elements are taken to be ten (n=10), isotropic and circularly distributed on a circumference of circle in x-y plane. b) the radius of the circle (r) of ten elements array with inter-element displacement 0.5λ is equal to 0.8 λ according to eq. (1). c) the received signals are considered to be statistically independent and uncorrelated. the proposed 3-d adaptive array antenna estimator in conjunction with (lcmvb) algorithm is tested, evaluated and compared with music df technique according to the following scenarios. asenario1:a two airborne transmitters are cosidered to be transmittedon a same frequency with equal output powers.the received signals are assumed to be arrived from different elevation and azimuth angles.θ1=45o, φ1=150o, θ2=60o, and φ2=200o.the input received powers areassumed to be equals and equal to 5db. figures(3,4,5)show the result of estimating elevation and azimuth angles in 2-d (θ �� φ versus snr) and estimating in 3-d (θ ��� φversus snr) of the two transmitters by the use of proposed adaptive system. it can be seen that the estimated angles in both planes are coincide with the true angles of arrival of received signals. since the input received powers are assumed to be equales (5 db), it can be seen that the proposed system gives equal output snr (14.1 db) for both received signals, which means that the proposed system cansimultaneously estimate(θ,φ and snr) parameters for all received signals. fig. 3. elevation angle θ estimation by proposed model. bassim sayed mohammed al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 3644 (2016) 40 fig. 4. azimuth angle φ estimation byproposed model. fig. 5. estimated θ and φ versus snr by proposedmodel. while figures(6,7,8) for music technique show the estimation of � ��� � angles versus df output level. it can be seen that the dfoutput level for the estimated signals are not related in any way to the received signals input powers, because the music df output level which is given by eq.(11) is related to the noise subspace eigen vector set (z�) and not to the input signals parameters.the accuracy of estimated angles are seemed to be identical for both cases. fig. 6. elevation angle θ estimation by music. fig. 7. azimuth angle φ estimation by music. fig. 8. estimated(θand φ)versus df level by music. 0 50 100 150 200 250 300 350 0 5 10 15 20 25 30 35 x: 200 y: 30.99 estimated azimuth-angle of arrival (degree) o ut pu t s n r l ev el x: 150 y: 31.01 phi =200. deg. snr=14.91 db phi =150. deg. snr=14.91 db 0 10 20 30 40 50 60 70 80 90 0 20 40 60 80 100 120 140 160 x: 60 y: 154.3 estimated elevation-angle of arrival (degree) m u s ic ( d f ) po w er l ev el ( db ) x: 45 y: 158.4 theta =60. deg.theta =45. deg. 0 50 100 150 200 250 300 350 0 20 40 60 80 100 120 140 160 x: 200 y: 154.3 estimated azimuth-angle of arrival (degree) m u s ic ( d f ) po w er l ev el ( db ) x: 150 y: 158.4 phi=200 deg.phi=150 deg. bassim sayed mohammed al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 3644 (2016) 41 bcenario 2:two cases are considered.first, the two transmitters are transmitting from the same azimuth angles and from different elevation angles θ1=30o, φ1=150o,θ2=60o, and φ2=150o.second,twotransmitters are transmitting from eqaul elevation angles and from different azimuth angles θ1=50o,φ1=100o,θ2=50o,and φ2=200o. the two sources transmit on the same frequency with different transmitting powers. the input received powers from sources are considered to6db and 9db it can be seen from figures(9and10) that the proposed system estimate ( �, � and snr) for the two transmitter in both cases with a high accuracy although the two transmitters transmit from the same azimuth or same elevation angles with different transmitting powers. it is also obvious that the output snr's of received signals are directly related to the input received powers from sources. the (6 db) input power gives (15.55 db) output snr while the (9 db) input power gives (18.58) db output snr in both figures, which means that the proposed system are fulfill the designing requirments for estimating (3-d) parameters. fig. 9. estimated (| ��� }) versus snr by proposed system for equal azimuth and different elevation angles . fig. 10. estimated (θ ��� }�versus snr by proposed system for different azimuth and equal elevation angles. cscenario 3:a three transmitters are transmitting on same frequency with different transmitting powers. the received signals are assumed to be from different elevation and azimuth anglesθ1=45o, φ1=150o, θ2=60o,φ2=200oand θ3=75o, φ3=250o.theinput received powers from sources are cosidered to be 6, 9 and 12 db. figure (11) shows (3-d) plot for proposed system.the result shows that the angle of arrival estimation for the three transmitters are quite accurate and identical to the angles of arrival estimated by music techniquesee figure (12). it can also be seen that the proposed system estimates the output snr's for the received signals and shows different output snr's levels,since the input powersof recived signals are assumed to be different while, a music technique hasn't this capability. figure (12) shows that the df level for the received signals which they have different input powers are equals this means that music technique can be considered a (2-d) estimator rather than (3-d) estimator as the case of proposed system. bassim sayed mohammed al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 3644 (2016) 42 fig. 11. estimated �| ��� }� versus snr by proposed model for three sources with different input levels. fig. 12. estimated (| ��� }� versus df level by music for three sources with different input levels. 7. conclusions a uniformly circular array antenna with a modified adaptive algorithm is proposed to be used as an angle of arrival estimator in two planes (θ and φ) and output snr estimator (i.e.3-d estimator). the proposed (3-d) angle of arrival estimation results shows that the system is equivalent to the music technique from the point of angle of arrival estimation accuracy view and it has a privilege over music that it can estimate output snr for the received signals under two planes angle of arrival estimation while music does not has this capability. the estimated output snr can be used to estimate the distance to the transmitting sources, since the estimated snr is directly related to the transmitted power and distance between transmitting source and estimator (receiving side). comparing the proposed model with the well know music technique shows that the proposed model does not need any hard ware or software orthogonality which is used by music to calculate noise subspace eigenvectors z�. the orthogonality techniques which are based on singular value decomposition (svd) technique or eigenvalue decomposition technique are computationally intensive and they need more ram size and more time processso that they might not be suited for real time application where the received signals must be tracked in real time. the optimum adapted weight vector woptm in the proposed system is directly calculated and used to estimate �, �and snr with minimum computing steps. this means that the proposed system can be used in a real time to track the received signals. the proposed model also offers the capability to analyze and listen to the received signals(hearing and technical analyzing features ) while performing angle of arrival estimation which is an important tools for supporting electronic war-fare counter measures(ecm) and electronic war-fare supporting measures (esm)activities against these sources. 8. references [1] bassim sayed and noori hussain “an alternative approach for angle of arrival estimation”, 8th european conference on antenna and propagation (eucap, 2014), pp.2639-2643, 2014. [2] bassim sayed and noori hussain “angle of arrival and signal to noise ratio estimation for broadband signals by phased adaptive array antennas”, 8th european conference on antenna and propagation (eucap, 2014), pp.311-315, 2014. [3] bassim sayed and noori hussain “adaptive array antenna used for signal to noise ratio and angle of arrival estimation” 7th european conference on antenna and propagation (eucap, 2013), pp.2000-2004, 2013. [4] x. liu and g. liao, “direction finding and mutual coupling estimation for bistatic mimo radar,” signal processing, vol.92, no.2, pp.517-522, 2012. bassim sayed mohammed al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 3644 (2016) 43 [5] s.shirvain moghaddam and f. akbari, “improving lms/nlms-based beam forming using shirvain-akbari array”, american journal of signal processing, vol. 2, no. 4, pp. 70-75, 2012. [6] s. shirvain moghaddam and f. akbari, “a novel ula-based geometry for improving aoa estimation”, eurasip journal on advances in signal processing, vol. 2011, no. 39, 2011. [7] s. shirvain moghaddam , f. akbari and v. t. vakili, “a novel array geometry to improve doa estimation of narrowband sources at the angles close to end fire”, in proceeding of 19th iranian conference on electrical engineering (icee2011), pp. 16,tehran,iran,may 2011. [8] s. kikuchi, h. tsuji and a. sano, "pairmatching method for estimating 2-d angle of arrival with a cross-correlation matrix," ieee antennas wireless propag. lett., vol. 5, pp. 35-40, 2006. ���� �� � � � �� ��� 1، ا� �د�12ا������� ا���ارز�� ا����� ،44 -36 )2016( 44 ����#� ا���ا!��ت ا��ا! �� ا���ر$� �� +���* زاو�� ا����ل #� �'&���ت �& �دة �ا �� ا��&,� ���� �� � � �� ا����������� ا�'�&%� ا�$��#�#"��/ ! � ا�� bassim_sayed@yahoo.com :ا�-�,� ا+��$�و() �� ا�� ط� ا!. ���# ا��ا��,� (b#ذج ا+d%�ع �b=>#;� ا��#ا���تا;) ھaا ا�-@? 0� ا!$�اح &�6#&� &=>#;� ھ#ا���ت ط#ر,� &7 (�6م &$��4 و3#ارز&�� 0/��. g�,#$ & (; ل#i#زاو,� ا� g�bj0 ت�-kl$& ��-k$� ��l3 ة��n& ء�p#p رة�!)$ bا� (n;+دي#ى ا#b%ى ا�#$ bوا� (atو uرة ا��d+ى ا#$ & g�bj0 v� �&#6�b�3ج ا� (; �bk$ bرات ا��اد,#,� ا��dw� ء�p#xا�)ywy (; ازي#$bا� g�bj$ا��#ا���ت ،)& $#,�ت �اي ا� �;#<=b� ي��kn$ام ا��j$��+ &g ا+� �bk$ bرات ا��dw� �n;ا�bء ا��p#xا3. وا��� ا�dرات ا�$�bj0 (; �<��$b7 ا. ا�pو �ح 0�$nb�6م ا��، (b#ذج ر,�p) �] و0� ���ء ��tن ��&') 0/-��) �] ا� �<k$j&دة و� .و;@=] ;) [�+ت &@��tت &$% �cوا,� ا�#i#ل ��dwرات ا�bk$ b] ;) ا�g�,#$ b ) (> ] ;) ا�#!b( ($��_ ا�>@a ان ا���6م ا�nb$�ح ا`ul ($��_ را�%� ;) ا�$g�bj ا�b$#ازياظ��ت �6#&� وatا�g�bj0 (; v & $#ى ا+�dرة ا�u ا��p#xء ا+;n) وا�%b#ديb�3ج ا� (;)(ywy g�bj0 رات ا��اد,#,� ). اي�d+ل ا#iزوا,� و g�bj0 �!د �bj$� ����] م�j$ bرة ا��d+د ا���� ا�$=��4 ا�lb#ر &$%n0 g& �k=@$bا� g�bj$ا� �!�� �d;��& دي#b%وا� (n;+ا g�,#$ bا� (; �bk$ bلا�#i#زوا,� ا� g، ��$&#6�& ���n0 uk` ��kx;ا ��� �]�$nb6#&�ا��b�3ج ا� (; �bk$ bرات ا��dw� ء�p#xا� uرة ا��d+ى ا#$ & g�bj0 7�l$ 0 ��)#t ر#lb4 ا��� .ا�$= ��n%0 .!ن &�دي ا��tا!. و �'��%& b!و uت [ ���� وا���kb` uح ,@$�ج ا��$nb�6م ا����� ا�$=��4 ا�lb#ر &$%�د ا اٌ ا��3ا ا�n0 g& ي ,@$�جaرة وا��d+ �ا���6م ا�nb$�ح ,%. ا�u [ �ب &$'��ت ا+,'�n,�l� g ا�$@�k. ا�b� . k $b=>#;�ت ا+�dرة وا��p#xء �b6)+ا g& �<k�0 .!ا+!$=�د,� ا ��]��&g ا� �&� ;) `��kbت ا�$g�bj ا�ywg) ;) و!b وا[� &g. ا��ادارj$ bا�>%��� ا�. د. سهامة وميرفت al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 8, no.3, pp 95 -107 (2012) )al-cu-mg( سبیكة أساس ذات لمتراكبات ةیالمیكانیك الخواص دراسة میرفت مھدي الجنابي سھامة عیسى صالح جیةالجامعة التكنولو/ ھندسة الموادقسم (received 6 february 2011; accepted 23 october 2011) الخالصة مقواة) al-cu-mg( بسبیكة والمتمثل معدني أساس ذات متراكبة مواد من) cm 1.5( وقطرھا) cm 13( طولھا قضبان تحضیر الحالي البحث تناولی تقنیة باستخدام السباكة بطریقة المتراكبة والمواد األساس سبیكة حضرت) .and3.5, 2.5, 1.5% ,5.5(ھي مختارة وزنیھ بنسب) zro2( الزركونیا بدقائق باالعتماد المتراكبة المواد من رئیسیتین مجموعتین تحضیر تم ذلك عن فضال األساس، سبیكة في الزركونیا دقائق لتشتیت) vortex technique( الدوامة mspm( المتمثلة الزركونیا لدقائق الحبیبي الحجم على µµ 1.0.50 mspm(و)<≤ µµ 50.63 تأثیر الدراسة وتضمنت. التوالي على)<≤ تأثیر ودراسة مختلفة أزمنة وخالل) 0c 185( درجة عند التعتیق عملیة عن فضال الالحقة التشكیل وعملیة) 5050c( درجة عند المحلولیة الحراریة المعاملة حبیبات ذات المتراكبة للمادة المجھریة البنیة أن المجھري الفحص نتائج أظھرت وقد .المیكانیكیة خواصھا بعض على كونیاالزر بدقائق األساس سبیكة تقویة الزركونیا نسبة زیادة مع الشد ومقاومة الصالدة من كل قیم ازدیاد النتائج بینت فقد الشد ومقاومة الصالدة فحص یخص فیما أما ، األساس السبیكة من انعم على التوالي ثم تسلك المادة سلوكا مغایرا ولكنھا تبقى عند قیم ) 140h.v(,)570h.v(والبالغة %3.5لتصل الى اعلى قیمة لھا عند النسبة الوزنیة ضافةالم لدقائق الحبیبي الحجم یرتأث أما .المضافة الزركونیا نسبة زیادة مع باستمرار تقل المطیلیة قیم إن لوحظ حین في اعلى مما ھي علیھ في السبیكة االساس ولكن تبقى الزركونیا لدقائق الحبیبي الحجم زیادة مع الشد مقاومةو الصالدة قیم في قلیل انخفاض ھنالك أن لوحظ فقد المیكانیكیة الخواص على الزركونیا الحبیبي الحجم زیادة مع المطیلیة قیم في قلیلة ةزیاد ھنالك بینما على التوالي ) 110h.v(,)210h.v(اعلى مما ھي علیھ في السبیكة االساس والبالغة . األساس السبیكة في علیھ ھي مما اقل تبقى ولكنھا ).مغنسیوم -نحاس -المنیوم( تقنیة الدوامة، مواد متراكبة، دقائق الزركونیا، سبیكة : لكلمات المفتاحیةا المقدمة .١ ) al – cumg( مغنیسیوم نحاس – األلمنیوم سبیكة تعد كثیر من المجاالت المدنیة في المھمة األلمنیوم سبائك إحدى الحراریة المعاملة بعد السبیكة ھذه تكتسب حیثوالعسكریة ھذا بالترسیب األصالد على قابلیتھا نتیجة عالیة میكانیكیة خواص جھودھم بتكثیف المجال ھذا في الباحثین من الكثیر في حفزَّ مما مواد إنتاج في األلمنیوم سبائك استخدام كانیةإم حول البحثیة مقواة ألمنیوم أساس ذات (composite materials)متراكبة من بأكثر المیكانیكیة خواصھا تحسین بھدف سیرامیكیة بحبیبات التقویة من النوع ھذا أن].1[ بالتشتیت األصالد آلیة ومنھا آلیة خامل طور تیتتش طریق عن وذلك الفلزیة األنظمة في یستعمل ، واحد مایكرون من أقل أقطار وذات دقائق من یتكون صلد من ) 15%( التتجاوز قلیلة بنسب عادة المضافة الدقائق وتكون مادة تتحمل عندما بالتشتیت التقویة تنشأ وزن المادة المتراكبة المتراكبة المادة على المسلط االجھاد من االكبر الجزء االساس المتكونة االنخالعات حركة اعاقة على المشتتة ائقالدق تعمل بینما یعتمد التقویة مدى ان فیھا، التشقق حدوث ومنع االساس المادة في . ]2[ الحركة لھذه اعاقتھا في المشتتة الدقائق فاعلیة على ھي التقویة من النوع ھذا بھا یتصف التي الممیزات ومن بالترسیب داالصال مثل اخرى تقویة الیة مع جمعھ امكانیة )precipitation hardening (للتقویة مشابھا یكون والذي على یعمل صغیر حبیبي بحجم ثاٍن طور وجود حیث من بالتشتیت رفع عند یتكون الطور ھذا لكن السبیكة في االنخالعة حركة اعاقة عند والتعتیق االخماد عند ویترسب عالیا السبیكة حرارة درجة ذات متراكبة مواد تصنیع عملیة إن . منخفضة حرارة درجة الظروف ھذه وفي عالیة حراریة درجات عند تتم معدني أساس األساس المادة بین والمیكانیكي الكیمیائي التالؤم مشكلة تبرز بالتفاعالت الكیمیائي التالؤم مشكلة ترتبط التقویة، وطور ماأ المشكلة ھذه وتحل الفاصلة السطوح عند واإلتصال الكیمیائیة منخفضة حرارة درجات عند إنجازھا یمكن تصنیع تقنیة باستعمال من الكثیر ھناك وعلیھ.ثرمودینامیكیًا مستقرة أطوار بإختیار أو یومنا الربع األخیر من القرن الماضي وحتى منذ تعمل الدراسات المواد تصنیع طرق على التعدیالت من العدید أجراء في ھذا metalmatrix)عدنيالم األساس ذات المتراكبة composite) منھا تقنیة الترشیح بالعصر)infiltration squeeze ( من قبل الباحث)mortensen (]3[ وذلك من اجل الوصول الى افضل تغلغل للسائل المعدني في الفراغات البینیة وزیادة تبلل االلیاف لمادة االساس لمجموعة من االلیاف القصیرة وفي تحضیر مادة . تراكبة خواص افضلمما اكسب المادة الم ) fe3c( متراكبة ذات اساس من االلمنیوم المقوى بالسمنتیت )mechanical alloying(استخدمت تقنیة السباكة المیكانیكیة المعاملة , طحن المساحیق(تحت ظروف تحضیر مختلفة ]4[ واظھرت ) ودرجة حرارة الكبس وزمن ,حیقالحراریة للمسا كما .التوافق مابین مادة االساس ومواد التقویةنتائج الفحص )2012( 107-95 ، الصفحة3 ، العدد 8 مجلة الخوارزمي الھندسیة، المجلد سھامة عیسى صالح 96 اتجھت البحوث الى دراسة تاثیر عناصر السبك ومواد التقویة وحجم وشكل مواد , المضافة الیھا وتاثیر كل من الكسر الحجمي في عام .التقویة المضافة في الیة التصلید بالتشتیت لھذه الدقائق ن بدراسة البنیة واخرو ]nawal (]5(قامت الباحثة ) 1983( ) vortex( محضرة بطریقة الدوامةالتركیبیة لمادة متراكبة والحظوا ان حبیبات االلومینا تتجمع على طول الحدود البلوریة كما استنتجوا ان الصالدة ومقاومة الشد قد تحسنت . وداخل الخالیا 250( والعالیة حواليعند الفحص في درجات الحرارة االعتیادیة 0c .( دراسة من قبل الباحثوفي)knneko( ]6[ بتحضیر مادة ,tic(متراكبة من االلمنیوم مدعمة بدقائق سیرامیكیة متنوعة sic, al2o3 ( باستخدام طریقة التسبیك المیكانیكي استنتجوا ان التوزیع المتجانس للدقائق مع الحجوم الحبیبیة الناعمة اعطى نیة تصلید سبیكةوفي دراسة حول امكا. خواص میكانیكیة جیدة )al4%cu ( باكثر من الیة وذلك بدمج الیتي التصلید بالتشتیت والتصلید بالترسیب باستخدام دقائق االلومینا كمادة تقویة ودقائق المغیسیا كمادة معززة للتبللیة واستنتج ان الصالدة المایكرویة لتصل الى اعلى قیمھا البالغة تزداد مع زیادة نسبة االلومینا )136h.v (وذات حجم %0.5عند النسبة الوزنیة لاللومینا بینما تقل قیم الصالدة مع زیادة الحجم الحبیبي , )0.5µm(حبیبي كما استخدمت تقنیة .]7[وعند نسب مغیسیا ثابتة لدقائق االلومینا بتشتیت و) al2219(السباكة في تحضیر مادة متراكبة ذي اساس ھرت النتائج ان معدالت واظ sicنسب وزنیة مختلفة من دقائق اما تاثیر . ]sic ]8البلى للمادة المتراكبة تقل مع زیادة دقائق μm 40اضافة دقائق كاربید السلیكون ذات حجم حبیبي ثابت المحضرة بتقنیة السباكة بالمزج فقد درست ) al-si( على سبیكة %8 والحظوا ان التدعیم بنسبة ]9[ وجماعتھ) ranjit( من قبل ادى الى زیادة قیم الصالدة ومقاومة الشد واالنضغاط %12الى ادى الى sicبدقائق %18وعند التدعیم بنسبة) al-li(لسبیكة انخفاض ھذه الخصائص ولكن بقیت اعلى مما ھي علیھ في سبیكة ادى الى تقلیل زمن sicاالساس وكما استنتجوا ان التدعیم بدقائق وفي .المتراكبة المعتقة الوصول الى قیم الصالدة العظمى للمادة على دورات الفشل sicدراسة حول تاثیر الكسر الحجمي لدقائق میتالورجیة المساحیق المحضرة بتقنیة) 2124al-si-cu(لسبیكة ]10[المحضرة بتقنیة السباكة ) a57g/al-si-mg( وسبیكة فقد لوحظ انخفاض مقاومة الكالل للمادة المتراكبة ذات االساس )a57g (الى)25mpa (عند دورات الفشل البالغة )في )106 ) 2124(حین بلغت مقاومة الكالل للمتراكب ذات االساس عند نفس دورات الفشل، كما لوحظ ان زیادة ) 363mpa(الى ان .ادى الى انخفاض في مقاومة الكالل sicالحجم الحبیبي لدقائق ادت ) ai-si( الى سبیكة alnاضافة دقائق من نترید االلمنیوم 89h.vلسبیكة االساس الى 44h.v لى زیادة قیم الصالدة منا ومن الدراسات . ]aln % wt 5%]11للسبیكة المدعمة بنسبة riceبدقائق من رماد قشور الرز a356.2الحدیثة تدعیم سبیكة husk ash والمحضرة بتقنیة السباكة بالمزج فقد لوحظ ان زیادة وزیادة اض في قیم الكثافة نسبة التدعیم بالدقائق یؤدي الى انخف كما درست . ]12[ قلیلة في قیم الصالدة للمادة المتراكبة المحضرة المضافة المتمثلة بااللومینا والزركونیا تاثیر نوعیة دقائق التقویة والمحضرة بطریقة السباكة باستخدام ) al-cu-mg( الى سبیكة الل والصالدة تقنیة الدوامة فقد لوحظ ازدیاد قیم كل من مقاومة الك اما تاثیر نوعیة الدقائق فقد . مع زیادة نسب دقائق التقویة المضافة لوحظ ھناك زیادة ملحوظة في قیم مقاومة الكالل والصالدة بالنسبة للمادة المتراكبة المقواة بااللومینا مقارنة مع تلك المقواة . ]13[بدقائق الزركونیا بأكثر) al–cu–mg( سبیكة تصلید الى الحالي البحث یھدف الشد بمقاومة والمتمثلة المیكانیكیة خواصھا بعض ودراسة آلیة من الزركونیا دقائق إضافة خالل من والصالدة والمطیلیة القصوى )zro2 (تأثیر دراسة على عالوة األساس السبیكة منصھر الى السبیكة الى المضافة) zro2( الزركونیا لدقائق الحجم الحبیبي . األساس العملي الجزء .٢ من بھ تتمتع لما التحضیر في السباكة تقنیة اعتماد تم والمرونة الواطئة الكلفة ومنھا غیرھا عن تمیزھا مواصفات سبیكة حضرت مختلفة وأحجام بأشكال نماذج تصنیع في العالیة كتلة ذات النقي، االلمنیوم بصھر وذلك) al-cu-mg( االساس نوع كھربائي فرن وباستعمال رافیتالك من بودقة داخل معلومة، )carbolite (حرارة درجة عند الصھر عملیة اجریت )750 oc (داخل الى اغمر التام االنصھار حدوث من التاكد وبعد ومحفوظا) 4(% وزنیة بنسبة النقي النحاس من رایش المنصھر عملیة رافق) aluminum foils( االلمنیوم من رقائق داخل من قضیب باستعمال مستمر بشكل المنصھر حریكت مباشرة الغمر بنسبة النقي المغنیسیوم من رایش اضافة تم ذلك بعد الصلب الحدید بھا تم التي الطریقة وبنفس المنصھرة السبیكة الى) 1.5(% وزنیة سكبت ذلك بعد المستمر التحریك مع النحاس رایش اضافة الصلب لحدیدا من الشكل اسطوانیة قوالب في البودقة محتویات الى والمسخنة مسبقا )13cm( وارتفاع) 1.5cm( قطر ذات .للمنصھر المفاجئ التبرید حدوث لمنع) 0c 250( حرارة درجة ١ الجدول .األساس للسبیكة الكیمیائي التحلیل si fe cu mn mg zn ti cr ni pb sn sb al العنصر النسبة %المئویة 0. 22 21 7 0. 18 72 5 4. 28 82 6 0. 46 85 1 1. 28 79 3 0. 09 89 8 0. 02 90 5 0. 00 78 6 0. 00 45 8 0. 00 14 4 0. 00 55 7 0. 01 17 1 r em % المتراكبة المادة حضیرت. ١.٢ تقنیة باستعمال بالمزج اكةالسب بطریقة المتراكبة المادة أنتجت-- السبیكة تقطیع تم وعلیھ) vortex technique( الدوامة منھا المطلوب الوزن تحدید لغرض صغیرة قطع الى االساس دقائق توزیع ولتجانس.التقویة لمادة الوزني الكسر الى استنادا )2012( 107-95 ، الصفحة3 ، العدد 8 مجلة الخوارزمي الھندسیة، المجلد سھامة عیسى صالح 97 كھربائي خالط الغرض لھذا عملاست المنصھر داخل الزركونیا ،مقاومة التصدأ مادة من بمروحة ومزود الفوالذ من مصنوع المنصھر تدویر وتم البودقة داخل الى الكھربائي الخالط أنزل تم ذلك وبعد داخلھ دوامة على للحصول) r.p.m 700( بسرعة 250) ةحرار درجة الى مسبقا المسخنة الزركونیا دقائق ةاضاف 0c) بعمل االستمرار مع المنصھر داخل الى الرطوبة الزالة المعدنیة القوالب في المنصھر صب ذلك بعد الكھربائي الخالط ) 0c 250( حرارة درجة الى مسبقا والمسخنة الشكل االسطوانیة في الزركونیا لدقائق المستعملة النسب یوضح) 2( والجدول .االساس السبیكة -٢الجدول .االساس السبیكة في المستعملة الزركونیا نسب grain size (μm) zro2 (%) samples a al – 4%cu – 1.5%mg μm 0.1≥ p.s ≥ μm 50 1.5 a1 2.5 a2 3.5 a3 5.5 a4 μm 50 ≥ p.s ≥ μm 63 1.5 b1 2.5 b2 3.5 b3 5.5 b4 النماذج یعتقط. ٢.٢ على والحصول المتراكبة للمواد الصب عملیة اكمال بعد متراكبة مواد على الحصول ولضمان الشكل اسطوانیة نماذج المحضرة االسطوانیة النماذج ونھایة بدایة اھملت فقد متجانسة خشیة) 0.5cm( بمقدار واالسفل االعلى من عینة كل بقطع وذلك تشكیل عملیة اجراء تم ،فیھا التقویة لمادة التوزیع تجانس عدم من بدقائق المدعمة السبیكة وكذلك االساس لسبیكة البارد على اجریت .)5tons( مقداره حمل بتسلیط وذلك ،)zro2( الزركونیا والمواد االساس السبیكة من لكل للنماذج الحراریة المعاملة بعض من والتخلص الحراري التجانس لغرض المنتجة المتراكبة متجانس بشكل االطوار توزیع وضمان كاالنعزال السباكة یوبع 505( حرارة بدرجة المحلولیة المعاملة اجریت وقد الصبة في oc (ذلك بعد تبعھا البارد بالماء االخماد ثم ساعات اربع مدة واالبقاء) oc 185( حرارة درجة الى بالتسخین وذلك تعتیق عملیة ) .2hr-18( مابین مختلفة زمنیة لفترات الشد اختبار. ٣ حسب المصنعة النماذج على الشد اختبارات اجریت instron universal( عنو جھاز باستعمال القیاسیة المواصفات machine (طراز)القصوى الجھاز حمولة ،)22333 )200kn (والشكل.1982 المنشأ یاباني )الصور یوضح) 1 .الفحص دوبع قبل الشد اختبار لعینات الفوتوغرافیة .الفحص بعد الشد اختبار لعینات الفوتوغرافیة الصور -١الشكل )2012( 107-95 ، الصفحة3 ، العدد 8 مجلة الخوارزمي الھندسیة، المجلد سھامة عیسى صالح 98 الصالدة اختبار. ٤ حیث المحضرة العینات على الدقیقة الصالدة فحص اجري راس بزاویة ماسي ھرم من الفحص في المستعمل الجھاز یتكون )136o (مقداره حمل تسلیط تم حیث )0.5 kg (مدة )5sec. ( وحسبت قیم الصالدة من العالقة الناتج االثر قطر قیاس تم بعدھا :التالیة 2854.1. d pvh = -:حیث ان p :الحمل المسلط d :قطر االثر نوع ضوئي مجھر باستعمال المجھري الفحص اجراء تم )nikon (اجراء اوال تم ان بعد رقمیة بكامیرا مزود المنشأ یاباني تنعیم اوراق باستعمال وذلك للعینات والتنعیم التنظیف عملیات اما ،) 800،1200 ، 600، 180،320(التدرج وحسب مختلفة النسب حسب االظھار محلول فیھا لاستعم فقد االظھار عملیة : االتیة والمكونات )1%hf + 1.5%hcl + 2.5%hno3 + 95%h2o. ( والمواد االساس السبیكة نتھاتضم التي االطوار معرفة لغرض السینیة باالشعة الحیود فحص اجراء تم فقد المحضرة المتراكبة الحراریة المعاملة اجراء عند وكذلك الغرفة حرارة درجة عند ومادة) pw1840( نوع جھاز باستعمال والتعتیق، المحلولیة ) .λcu=1.5405 ao( مقداره موجي بطول النحاس الھدف من والمناقشة تائجالن. ٥ السینیة األشعة بحیود الفحص نتائج. ١.٥ الغرف ة ح رارة درج ة عن د الس ینیة األش عة حی ود أنم اط م ن وبع د قب ل الزركونی ا ب دقائق المق واة والس بیكة األس اس لس بیكة وخ الل ) 1850c( ح رارة درج ة عن د والتعتیق المحلولیة المعاملة األشعة حیود فحص ائجنت یوضح) 3( الجدول) 8hr( مقداره زمن الس باكة بع د) al-cu-mg(األس اس للس بیكة الس ینیة الس ینیة األش عة حی ود فح ص نت ائج یوض ح) 4( الج دول.مباش رة المحلولی ة السباكة والمعاملة بعد )al-cu-mg( األساس للسبیكة .(8hr)عند فترة مقدارھا والتعتیق للم ادة الس ینیة األش عة حی ود فح ص نتائج یوضح )5(الجدول .مباشرة السباكة بعد) al-cu-mg( سبیكة أساسھا التي المتراكبة للم ادة الس ینیة األش عة حی ود فح ص نت ائج یوضح) 6( الجدول اما بع د) al-cu-mg(الح الي البح ث س بیكة أساس ھا الت ي المتراكب ة عن د فت رة مق دارھا والتعتی ق المحلولی ة والمعامل ة الس باكة (8hr). الس ینیة األش عة حی ود فح ص نت ائج یوض ح ) 7( والج دول .) zro2( الزركونیا دقائق لمسحوق -٣الجدول .مباشرة السباكة بعد) al-cu-mg( األساس للسبیكة السینیة األشعة حیود فحص نتائج یوضح θ2 dm(ao) ds(ao) phase i/io 38.2 2.33 2.34 al 100 42.5 2.10 2.12 cu2al 10 44.4 2.08 2.03 mg2 cu6 al5 80 60.8 1.50 1.51 cual2 6 64.7 1.43 1.43 al 22 78.1 1.22 1.22 al 24 82.3 1.16 1.16 al 7 -٤الجدول .(8hr)رھا عند فترة مقدا والتعتیق المحلولیة السباكة والمعاملة بعد) al-cu-mg( األساس للسبیكة السینیة األشعة حیود فحص نتائج یوضح θ2 dm(ao) ds(ao) phase i/io 38.4 2.33 2.34 al 100 44.5 2.03 2.02 al 47 44.5 2.03 2.02 mg2 cu6 al5 40 60 1.43 1.43 al 22 60 1.43 1.41 cual2 7 78.3 1.21 1.23 cual2 16 82.4 1.16 1.17 cual2 3 )2012( 107-95 ، الصفحة3 ، العدد 8 مجلة الخوارزمي الھندسیة، المجلد سھامة عیسى صالح 99 -٥-الجدول السباكة بعد) al-cu-mg( سبیكة أساسھا التي) %5wt(المحضرة عند نسبة تدعیم المتراكبة للمادة السینیة األشعة حیود فحص نتائج یوضح .مباشرة θ2 dm(ao) ds(ao) phase i/io 38.3 2.34 2.34 al 100 42.3 2.13 2.18 zro2 6 44.5 2.03 2.02 al 47 47.1 1.92 1.98 zro2 8 64.7 1.43 1.46 mg2cu6al5 35 78.2 1.22 1.23 cual2 20 82.5 1.16 1.17 cual2 3 -٦الجدول السباكة بعد) al-cu-mg( سبیكة أساسھا التي) %5.5wt(المحضرة عند نسبة تدعیم المتراكبة للمادة السینیة األشعة حیود فحص نتائج یوضح .)8hr(ة مقدارھا عند فتر والتعتیق المحلولیة والمعاملة θ2 dm(ao) ds(ao) phase i/io 37.9 2.36 2.31 mg2cu6al5 80 44 2.05 2.02 al 47 77.9 1.22 1.26 zro2 10 28.1 1.17 1.17 cual2 9 -٧لجدولا .)zro2( الزركونیا دقائق لمسحوق السینیة األشعة حیود فحص نتائج یوضح θ2 dm(ao) ds(ao) phase i/io 24.1 3.68 3.63 zro2 14 27.9 3.19 3.16 zro2 100 31.2 2.85 2.83 zro2 65 33.9 2.63 2.61 zro2 20 49.7 1.83 1.84 zro2 18 55 1.66 1.65 zro2 14 59.4 1.55 1.54 zro2 10 65.2 1.42 1.42 zro2 6 70.7 1.32 1.30 zro2 2 )2012( 107-95 ، الصفحة3 ، العدد 8 مجلة الخوارزمي الھندسیة، المجلد سھامة عیسى صالح 100 الدقیقة الصالدة فحص نتائج . ٢.٥ األساس للسبیكة الصالدة فحص نتائج. ١.٢.٥ زمن زیادة تأثیر یوضح والذي) 2(الشكل مالحظة خالل من بعد) al-cu-mg( االساس للسبیكة الصالدة في قیم التعتیق عند والتعتیق) 0c 505(درجة عند المحلولیة المعاملة إجراء بعد األساس السبیكة صالدة ان یالحظ) 0c 185(حرارة درجة مدة التعتیق زیادة مع تزداد والتعتیق المحلولیة والمعاملة الصب ویعود) 12hr( مقدارھا مدة تعتیق عند لھا قیمة أعلى إلى لتصل حیث) cual2( الطور من جدا صغیرة دقائق ترسیب إلى ذلك إلى یؤدي مما االنخالعات حركة إعاقة على الدقائق ھذه تعمل مدة زیادة وباستمرار ,تدریجیا مقاومتھا وزیادة السبیكة صلیدت ویعود الصالدة قیم انخفاض یالحظ) 12hr( من اكثر إلى التعتیق جسیمات وتكون المترسبة الدقائق تجمع الى االنخفاض ھذا سبب األرضیة بین التطابق انفعاالت فقدان عن فضال حجما اكبر تكون على تعمل الحراریة املةالمع أن ، [14]المترسبة والدقائق السبك لعناصر االنتشاریة عن العملیات ناتجة وسطیة أطوار األشعة حیود فحص نتائج أكدتھ ما وھذا) والمغنیسیوم النحاس( أن حیث) mg2cu6al5( الطور ظھور الحظی) 3( جدول السینیة تاخیرعملیة وبالتالي والنحاس األلمنیوم سحب إلي یؤدي ظھوره إلى یؤدي سوف تقدم ما كل ان وعلیھ) cual2( لطورا ترسیب قیم الى انخفاض یؤدي مما االنخالعات لحركة اقل عوائق تشكیل . الصالدة للسبیكة المحلولیة المعاملة بعد التشكیل عملیة إجراء بعد أما للسبیكة الصالدة قیم زیادة) 2( شكل خالل من فنالحظ االساس ) 8hr( إلى الزمن وانخفاض لتشكیلا قبل علیھ كانت عما األساس عملیة ان الى ذلك في السبب ویعود العظمى الصالدة إلى للوصول زیادة إلى تؤدي سوف المحلولیة المعاملة بعد البارد على التشكیل البینیة والذرات االنخالعات مثل( البلوریة البنیة عیوب عدد كةحر البلوریة البنیة عیوب تعرقل سوف وعلیھ) والخلوات اللدونة، من وتخفض المقاومة من بالتالي فترفع االنخالعات مدة سرعة من زاد قد البارد على التشكیل ان ذلك على عالوة االنتشار سرعة في سبب مما كثیرة فراغات تكون بسبب التعتیق . [14] البنیة تحول عملیات سرعة تزداد سوف أي .ة للسبیكة األساستأثیر مدة التعتیق على قیم الصالد -٢شكل المتراكبة للمادة الصالدة فحص نتائج. ٢.٢.٥ الزركونیا لدقائق الوزنیة النسبة تاثیر یبین) 3( الشكل المعاملة إجراء بعد األساس لسبیكة الصالدة في قیم المضافة السبائك من ولمجموعتین) 0c 505( حرارة درجة عند المحلولیة بدقائق مدعمة) a( األولى وعةالمجم )2(المبینة في الجدول ) 50µm p.s≥0.1µm( بین یتراوح الحبیبي حجمھا الزركونیا الحبیبي حجمھا الزركونیا بدقائق مدعمة) b( الثانیة والمجموعة قیم ان الشكل من یالحظ).63µm p.s≥50µm( بین یتراوح الیھا الزركونیا دقائق إضافة عند تزداد األساس لسبیكة الصالدة الزركونیا لدقائق الوزنیة النسبة زیادة مع تزداد الزیادة نسبة وان الوزني الكسر عند لھا قیمة اعلى الى لتصل المجموعتین ولكال الى یعود االساس لسبیكة الصالدة قیم في الزیادة ان) % 3.5( حجمھا یزید والتي الدقائق ھذه تعمل اذ الزركونیا دقائق طبیعة بسبب وذلك االساس سبیكة هلتشو كعوائق واحد مایكرون عن عن حجمھا الیزید التي الدقائق وان كما ، [15 ] العالیة صالدتھا )0.1μm (اعاقة على تعمل األساس سبیكة بنیة داخل والمتشتت یساھم سوف وبالتالي االساس مادة في المتكونة االنخالعات حركة لسبیكة الصالدة قیم زیادة اما .الصالدة قیمة في زیادة النوعین كال ینسب ان یمكن الزركونیا لدقائق اإلضافة نسبة زیادة مع االساس مختلفة وزنیة وبنسب االساس سبیكة في صلدة دقائق وجود الى بعض تغیر الى یؤدي سوف الحبیبي الحجم اختالف الى عالوة اآلتیة تبعا للعالقة) dp(الدقائق بین المسافة ضمنھا ومن العوامل :[ 16] ( )p p p v v dd −= 1 3 2 2 …(1) -:ان حیث d :الدقائق حجم )μm( vp :للدقائق الحجمي الكسر dp:الدقائق بین المسافة على تعمل سوف شروط ھكذا في الزركونیا دقائق أن وجود من العالیة الوزنیة النسب عند اكبر بنسبة االنخالعة حركة اعاقة المشتتة الدقائق ھذه خالل االنخالعة تمر ولكي المضافة، قالدقائ كافیا یكون ان یجب المسلط االجھاد فان االساس سبیكة طور في الحمل زیادة یتطلب سوف ذلك فان وبالتالي االنخالعة لحني .[14-15] الصالدة قیم في زیادة یعني وھذا المسلط اعلى بنسبة الزركونیا دقائق وجود فان تقدم ما على عالوة كثیرة تجمعات تواجد احتمال زیادة الى یؤدي قد) %3.5( من من یخفض مما متجانس غیر بشكل االساس سبیكة داخل ومنثورة یالحظ كما الیھا، وصلت التي العلیا قیمھا عن قلیال الصالدة قیم كال في متناظرا الصالدة قیم في الزیادة معدل إن) 3(الشكل من بالنسبة الصالدة قیم في قلیلة زیادة رقفا سوى المجموعتین نسبة على المجموعة ھذه احتواء الى ذلك ویعود) a(للمجموعة تقویة على تعمل جدا الصغیرة الدقائق من محددة غیر وزنیة نسبھا تحدید على الحالي البحث تعذر والتي بالتشتیت السبیكة . الفصل في دقیقة تقنیات من تتطلب لما الوزنیة )2012( 107-95 ، الصفحة3 ، العدد 8 مجلة الخوارزمي الھندسیة، المجلد سھامة عیسى صالح 101 تاثیر النسبة الوزنیة لدقائق الزركونیا المضافة للسبیكة -٣-شكل االساس على قیم الصالدة سبیكة على االصطناعي التعتیق عملیة تأثیر. ٣.٢.٥ المقواة االساس درجة عند مدة التعتیق تاثیر یبین) a,4-b-4( الشكالن ان في قیم) المحلولیة ملةالمعا اجراء بعد) (0c 185( حرارة بنسب الزركونیا بدقائق المقواة) al-cu-mg( لسبیكة الصالدة جزیئیة احجام وذات) 1.5, 2.5, 3.5, 5.5%( مختلفة وزنیة mspm( مختلفة µµ 1.0.50 ≥> ( m50s.pm63( و µ≥>µ (الترتیب على . في یؤثرال الزركونیا دقائق اضافة ان الشكلین من یالحظ حیث زیادة مع تزداد السبائك لكافة الصالدة قیم ان اذ التعتیق مراحل مقدارھا تعتیق عند مدة العظمى قیمھا الى لتصل مدة التعتیق )12hr (عن تزید الزركونیا بدقائق المقواة السبائك صالدة وان مع یزداد الصالدة في الزیادة معدل وان االساس لسبیكة مثیالتھا قیم ان ایضا ویالحظ المضافة للدقائق الوزني الكسر زیادة العظمى الصالدة قیم عن تزید المقواة للسبائك العظمى الصالدة اضافة ان الى یعود ذلك في والسبب الدقائق من الخالیة للسبائك الى یؤدي االساس السبیكة ارضیة في وتوزیعھا الزركونیا دقائق زیادة مدة مع الصالدة قیم في الزیادة وان السبیكة صالدة زیادة سبیكةال في التشبع المفرط الجامد المحلول تفكك الى یعود التعتیق )cual2(المستقرة االطوار وظھور التعتیق مراحل اثناء االنخالعة حركة عرقلة الى ستؤدي والتي) al2cumg(و اخرى الیة وجود عن فضال الصالدة، قیم زیادة الى وبالتالي حیث الزركونیا بدقائق المقواة السبیكة داصال عملیة في ساھمت واحد مایكرون عن الحبیبي حجمھا یزید التي الدقائق تعمل كعوائق االساس سبیكة ارضیة في متجانس بشكل والموزعة عالوة الصالدة قیم زیادة الى تؤدي وبالتالي االساس سبیكة لتشوه ةعرقل على تعمل حجما االصغر الزركونیا دقائق ان ذلك على [14 ] . الصالدة قیم زیادة وبالتالي االنخالعة حركة دقائق حجم في االختالف ان الشكلین من ایضا یالحظ كما حجم زیادة تؤدي وانما التعتیق في مراحل الیؤثر الزركونیا خالل للصالدة حصلت التي الزیادة معدل من التقلیل الى الدقائق قیم ان یالحظ اذ زركونیاال بدقائق المقواة للسبائك التعتیق مراحل للمجموعة الصالدة قیم عن قلیال تزید) a(للمجموعة الصالدة )b (من حبیبي اقل حجم ذات دقائق وجود الى یعود وذلك )0.1μm (المجموعة في)a (الصالدة قیم زیادة على تعمل والتي . اعاله ماتبین ضوء على )mspm µµ 1.0.50 ≥>( )4-a( )63µm p.s≥50µm ()4-b( تاثیر مدة التعتیق االصطناعي لسبیكة االساس المقواة بدقائق -٤شكل .الزركونیا على قیم الصالدة الصالدة في قیم البارد اللدن التشكیل عملیة تأثیر. ٤.٢.٥ البارد على التشكیل عملیة تأثیر یبینان) a,5-b-5( الشكالن لكافة االصطناعي التعتیق في مراحل الالحقة یةالمحلول والمعاملة التشكیل عملیة ان الشكلین خالل من لوحظ وقد المحضرة، السبائك للوصول المطلوبة المدة انخفاض الى ادت المحلولیة والمعاملة الى التشكیل عملیة قبل) 12hr( والبالغة العظمى الصالدة قیم الى )8hr (التشكیل، عملیة بعد الصالدة قیم وكذلك العظمى الصالدة قیم ان لوحظ كما قبل علیھ كانت عما زادت قد التعتیق مراحل خالل المحسوبة الى ذلك ویعزى المحضرة ، العینات ولكافة التشكیل عملیة اجراء كلھا للعینات المحلولیة والمعاملة البارد على التشكیل عملیة ان )2012( 107-95 ، الصفحة3 ، العدد 8 مجلة الخوارزمي الھندسیة، المجلد سھامة عیسى صالح 102 عالیة نسبة ینھاتكو بسبب وذلك التعتیق عملیة تسریع في ساھمت في تسبب مما قصیرة مسافات على تتجمع والتي الفراغات من لمناطق كنویة تعمل انھا على عالوة االنتشار عملیة تسریع [ 14]. الترسیب )mspm µµ 1.0.50 ≥>( )4-a( )63µm p.s≥50µm ()(4-b على البارد والمعاملة المحلولیة الالحقةتاثیر عملیة التشكیل -٥-شكل .على قیم الصالدة في االساس للسبیكة المضافة الزركونیا نسبة تأثیر. ٣.٥ العظمى الصالدة قیم الوزني الكسر مع العظمى الصالدة قیم تغیر یبین) 6( الشكل -al-cu( االساس السبیكة الى المضافة الزركونیا لدقائق mg (حیث. المضافة للدقائق الحبیبي الحجم تاثیر ىعل عالوة نسبة زیادة مع العظمى الصالدة قیم زیادة الشكل من یالحظ بعدھا تقترب قیم ) %3.5wt(لغایة النسبة المضافة الزركونیا المضافة الزركونیا نسبة زیادة معالصالدة العظمى من االستقرار المشكلة لعیناتل حصلت العظمى للصالدة قیم اعلى ان یالحظ كما الى ذلك یعزى حیث الحجمین، ولكال الزركونیا بدقائق والمقواة اوال والمتمثلة السبائك ھذه تصلید عملیة في الیة من اكثر اشتراك حبیبیة احجام ذات دقائق اضافة عن الناتج بالتشتیت باالصالد من دقائق اضافة خالل من الصالدة زیادة على عالوة دقیقة فضال) 1µm-50μm( بین حبیبیة تتراوح احجام اتذ الزركونیا مدة خالل بالترسیب االصالد ثم ومن بالتشكیل عن االصالد قد االلیات ھذه كل) (0c 185 حرارة درجة وعند) 8hr( مقدارھا .االصالد عملیة في شاركت الدقائق حجم تأثیر مالحظة یمكن) 6( الشكل خالل من وایضا حبیبيال الحجم زیادة مع تقل الصالدة مقی ان الحظی حیث المضافة یمكن وھذا االساس، السبیكة في علیھ مما اعلى تبقى ولكنھا :[16 ] العالقة أساس على تفسیره …(2) :حیث ان ti :االجھاد المطلوب لمرور االنخالعة. b′: متجھ بیرجر. gm :دة االساسمعامل القص للما. dp : 1(العالقة رقم (المسافة بین الدقائق (( لمرور االجھاد المطلوب بین العكسیة العالقة مالحظة یمكن وھذا الدقائق، لھذه الحبیبي الحجم ومربع الدقائق خالل االنخالعة مصحوبا سیكون الحبیبي الحجم قیمة في نقصان أي ان یعني االنخالعة لمرور لوبالمط االجھاد قیمة في ملحوظة بزیادة . الصالدة في قیم زیادة وبالتالي العالقة بین قیم الصالدة العظمى والنسب الوزنیة لدقائق -٦-شكل .الحبیبیة المختلفةالزركونیا المضافة للسبیكة األساس وباألحجام ρ ′ = d bgt m i . )2012( 107-95 ، الصفحة3 ، العدد 8 مجلة الخوارزمي الھندسیة، المجلد سھامة عیسى صالح 103 result of tesile test الشد فحص نتائج. ٤.٥ المقواة والسبائك االساس لسبیكة الشد حصف خالل من تم) 8hr( مدة ) 1850c( درجة عند والمعتقة محلولیا والمعاملة واجھاد الخضوع واجھاد القصوى الشد مقاومة قیم على الحصول القصوى الشد مقاومة قیم تغیر یبین) 7( والشكل. والمطیلیة الكسر المضافة ركونیاالز نسب مع المقواة والسبائك االساس للسبیكة الخضوع اجھاد قیم تغیر فیبّین) 8( الشكل اما .االساس للسبیكة من الحظی الزركونیاحیث بدقائق المقواة والسبائك االساس للسبیكة قیم وكذلك القصوى الشد مقاومة قیم زیادة) 8( و)7( الشكلین الزركونیا لدقائق الوزنیة النسب زیادة مع الخضوع اجھاد الى لتصل الوزنیة النسب زیادة مع بالزیادة القیم مروتست المضافة المادة تسلك ذلك وبعد) %3.5( الوزنیة النسبة عند لھا قیمة اعلى وقیمة القصوى الشد مقاومة قیمة تنخفض حیث مغایرا سلوكا ولكن المضافة للزركونیا الوزنیة النسبة زیادة مع الخضوع اجھاد وان االساس السبیكة في علیھ ھي مما اعلى قیم على محافظة تبقى بدقائق المقواة للسبائك القصوى الشد مقاومة قیم في الزیادة في والموزعة الصلدة الدقائق ھذه طبیعة الى یعود الزركونیا متانة زیادة على تعمل والتي مختلفة جزیئیة باحجام االساس سبیكة دقائق وجود جراء من بالتشتیت االصالد الیة خالل السبیكة خالل ومن) 0.1μm( عن الیزید الحبیبي حجمھا جدا غیرةص لتشوه كعوائق الدقائق ھذه تعمل سوف حجما االكبر الدقائق تواجد بسبب وذلك المادة في الحاصل التشوه تحویر أي األساس سبیكة عرقلة على تعمل سوف اآللیتین كال فان وعلیھ العالیة صالدتھا على عالوة ھذا المادة، تانةم زیادة وبالتالي االنخالعات حركة سوف مختلفة بنسب األساس سبیكة في الصلدة الدقائق ھذه وجود حینما وخصوصا) dp( الدقائق بین المسافة تقلیص على یعمل على تعمل سوف أعلى وزنیة وبنسب منتظم بشكل موزعة تكون خالل االنخالعة تمر ولكي اكبر بنسبة االنخالعة حركة عرقلة االجھاد فان االساس سبیكة طور في والموزعة تتةالمش الدقائق االجھاد ان وبما االنخالعة، لحني كافیا یكون ان یجب المسلط الدقائق بین المسافة مع عكسیا یتناسب االنخالعة لحني المطلوب نسبة بزیادة تقل الدقائق بین المسافة وان كما) 2( العالقة حسب االنخالعات لمرور اكبر اجھاد تسلیط یتم سوف لذلك الزركونیا . الدقائق خالل العالقة بین قیم الشد القصوى والنسب الوزنیة لدقائق ٧-شكل الزركونیا المضافة للسبیكة االساس والمعاملة المحلولیة عند درجة (505 oc) والمعتقة عند درجة(185 oc) مدة(8hr). الزركونیا بدقائق ةالمقوا للسبائك الخضوع مقاومة ان كما الدقائق بین للمسافة التربیعي الجذر مع عكسیا تتناسب سوف نسبة زیادة عند الخضوع مقاومة زیادة الى تؤدي سوف وعلیھ من اعلى بنسب الزركونیا دقائق وجود عند ولكن الزركونیا منتشرة كثیرة تجمعات تواجد احتمال الى یؤدي ذلك فان) 3.5%( من التقلیل یعني التجمعات ھذه وجود ان متجانسة، غیر بصورة قیم في النقصان وبالتالي االنخالعة حركة اعاقة في الدقائق دور . الخضوع اجھاد وقیم الشد مقاومة الخضوع والنسب الوزنیة لدقائق إجھادالعالقة بین قیم -٨-شكل المحلولیة عند الزركونیا المضافة الى السبیكة االساس والمعاملة .(8hr)مدة (oc 185)والمعتقة عند درجة (oc 505)درجة المطیلیة فحص نتائج. ١.٤.٥ لدقائق الوزنیة النسب مع المطیلیة قیم تغیر یبین) 9( الشكل الشكل من الحظی حیث. االساس الى السبیكة المضافة الزركونیا عند یةالمطیل قیم في نقصانًا ابدت) al-cu-mg( سبیكة ان من العكس وعلى مختلفة وزنیة بنسب لھا الزركونیا دقائق اضافة لدقائق حبیبيال الحجم زیادة مع المطیلیة قیم زیادة لوحظ فقد ذلك .االساس للسبیكة المطیلیة قیمة من اقل تبقى ولكنھا الزركونیا المتمثلة المیكانیكیة للخواص معاكسا سلوكا تسلك المطیلیة ان طبیعة الى یعزى ان یمكن ھذا ان والصالدة القصوى الشد بمقاومة الحبیبي الحجم في النقصان ان وكذلك الھشة السیرامیكیة الدقائق . المطیلیة تقلیل على یعمالن الدقائق بین والمسافة )2012( 107-95 ، الصفحة3 ، العدد 8 مجلة الخوارزمي الھندسیة، المجلد سھامة عیسى صالح 104 تغیر قیم المطیلیة مع النسب الوزنیة لدقائق الزركونیا -٩شكل 505)الى السبیكة االساس والمعاملة المحلولیة عند درجة المضافة oc) والمعتقة عند درجة(185 oc) مدة(8hr). المجھري الفحص نتائج. ٥.٥ األساس السبیكة من لكل المجھریة البنیة یوضح) 10( الشكل والمعاملة التشكیل اجراء وقبل السباكة عملیة بعد المتراكبة والمادة محلول عن عبارة األساس السبیكة لوحظ ان نجد حیث ، الحراریة الحبیبات كبر یالحظ كما األلمنیوم في النحاس من متكون جامد المتراكبة المادة اما ,واالنعزال كالفجوات السباكة عیوب ووجود مع االساس مع السبیكة مقارنة انعم حبیبات ذات بنیتھا ان فنجد .الناعمة ركونیاالز لدقائق وتكتالت تجمعات مالحظة السبیكة من لكل المجھریة البنیة فیوضح) 11( الشكل اما عملیة واجراء السباكة عملیة بعد المتراكبة والمادة االساس ومتجانسة ناعمة حبیبات عن عبارة السبیكة ان تبین حیث التشكیل اثناء المتكونة الفجوات غلق وكذلك التشكیل باتجاه وممتدة ما نوعا للمادة الزركونبا دقائق توزیع ان الحظی كما اكة،السب عملیة . التشكیل عملیة بعد انتظاما اكثر یكون المتراكبة االساس السبیكة من لكل المجھریة البنیة یوضح) 12( الشكل الحراریة والمعاملة والتشكیل السباكة عملیة بعد المتراكبة والمادة زیادة الحظی حیث العظمى الصالدة قیمة عند والتعتیق المحلولیة السبیكة في الزركونیا دقائق تشتیت المتكونة في حجم الحبیبات . االساس (a)سبیكة االساس (b)المادة المتراكبة ) a( األساس للسبیكة السباكة عملیة بعد المجھریة البنیة ١٠الشكل .)200x(قوة التكبیر ).b( المتراكبة والمادة )2012( 107-95 ، الصفحة3 ، العدد 8 مجلة الخوارزمي الھندسیة، المجلد سھامة عیسى صالح 105 (a)بیكة األساس س (b)المادة المتراكبة للسبیكة والتشكیل السباكة عملیة بعد المجھریة البنیة -١١الشكل .)200x(قوة التكبیر )b( المتراكبة والمادة) a( االساس (a)سبیكة األساس (b)المادة المتراكبة والمعاملة والتشكیل اكةالسب عملیة بعد المجھریة البنیة -١٢الشكل .)200x( قوة التكبیر األساس للسبیكة الحراریة )2012( 107-95 ، الصفحة3 ، العدد 8 مجلة الخوارزمي الھندسیة، المجلد سھامة عیسى صالح 106 االستنتاجات. ٦ یؤدي إلى تحسن ملحوظ ) hr 8( التعتیق عند زمن مقداره .١ .وواضح في المواصفات المیكانیكیة والمعاملة الحراریة الى تقلیل مدة التعتیق التشكیل عملیة أدت .٢ ى قیم الصالدة العظمى لسبیكة االساس المطلوبة للوصول ال .والمادة المتراكبة المنتجة االساس السبیكة بنیة في وتشتیتھا الزركونیا دقائق إضافة إن .٣ معیقة كحواجز عملت ولكنھا قیم الصالدة زیادة الى ادت الثانوي الطور دقائق لترسیب )cual2 (الى للوصول المطلوبة مدة التعتیق زیادة وبالتالي . العظمى الصالدة قیم إن قیم مقاومة الشد القصوى والصالدة للمادة المتراكبة .٤ المنتجة اعلى مما ھو علیھ في السبیكة االساس كما وتزداد ھذه القیم مع زیادة النسب الوزنیة لدقائق الزركونیا المضافة لتصل الى اعلى قیمھا عند النسبة الوزنیة لسبیكة االساس )3.5wt% ( البالغة)570mpa) (140kg/mm2( في ، حین تنخفض قیم المطیلیة للمادة المتراكبة ویزداد انخفاضھا مع زیادة النسب الوزنیة لدقائق الزركونیا المضافة لسبیكة .االساس الحجم الحبیبي لدقائق الزركونیا الى انخفاض في أدت زیادة .٥ قیم مقاومة الشد القصوى والصالدة في حین سببت زیادة .بي الى تزاید في قیم المطیلیة للمادة المتراكبةالحجم الحبی أثبتت نتائج الفحص بحیود األشعة السینیة ظھور دقائق .٦ في السبیكة األساس والمادة ) cual2( الطور الثانوي المتراكبة، فضال عن ظھور دقائق الزركونیا في نتائج .الفحص بحیود األشعة السینیة للمادة المتراكبة المصادر. ٧ [1] r.j .arsenault and r.m. fisher “micro structure of fiber and particulate sic in 6061 al composites”, j.scripta met.17(1983) 67-71. 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[8] basavarajappa, s., chandramohan, g., subramanian, r. and chandrasekar, a.,“dry sliding wear behaviour of al 2219/sic metal matrix composites” material science poland, 24 : 357-363(2006). [9] randit. bauri and m.k. surappa“processing and properties of al-li sic composites”sci.and tech. of advanced materials 8(2007) 494-502. [10] bayraktor, e., masounave, j., caplain, r. and bathias c., "manufacturing and damage mechanisms in metalmatrix composites", journal of achievements in materials and manufacturing engineering, 31/2: 294300(2008). [11] m.n. wahab, a.r. doud and m.j ghazali “preparation and characterization of stir costaluminum nitride reinforced aluminum metal matrix composites” international-j.of mechanical and material engineering(ijmme) 4(2) (2009) pp:115117. [12] d. siva prasad, a. ramakrishna “fabrication and characterization of a 356.2 rice husk ash composite using stir casting technique” international j. of eng. sci. and technology 2(21) 2010pp:7603-7608. [13] sahama,e. salih, sahib,m. al-saffar, and sarmad, i. ibrahim"effect of ceramic particies addition on the hardness and fatique values of the composite metal matrix(al-cu-mg) "j. of king abdulaziz university eng. sci., 21(2) 2010 pp127-150. [14] donald r. askeland and pradeep p. fulay"essentials of materials science and engineering" second edition, cengage learning (2010). [15] d.a. porter & k.e. easterling “phase transformations in metals & alloy” 2nd. ed., champan & hall india (1992). [16] d.a.thornton and v.colangclo"fund of eng. mat.", 1st ed, 1985 . sahama e. salih al-khwarizmi engineering journal, vol. 8, no.3, pp 95 -107 (2012) 107 study of mechanical properties of (al-cu-mg) alloy matrix composite sahama e. salih mervit m. al-jnabi department of materials engineering/ university of technology abstract the present research had dealt with preparing bars with the length of about (13 cm) and adiametar of (1.5 cm) of composite materials with metal matrix represented by (al-cu-mg) alloy cast enforced by (zro2) particles with chosen weight percentages (1.5, 2.5 ,3.5, 5.5 %). the base cast and the composite materials were prepared by casting method by uses vortex technique inorder to fix up (zro2) particles in homogeneous way on the base cast. in addition to that, two main groups of composite materials were prepared depending on the particles size of (zro2) ( )msizepm µµ 1.0.50 ≥> , ( )msizepm µµ 50.63 ≥> respectively. the study also contained the effect of insolution heat treatment at (505 0c) and the following forming process in addition to aging process at (185 0c) during different periods for all the prepared models. also we caried on the study of the effect of reinforcement the base cast process with zerconia particles (zro2) on some of its mechanical properties. the optical microscopy test should that the microstructures of the composite materials having fine grains as comparet with large grains more of the base cast. as for hardness test & tensile test results showed an increase in hardness & tensile strength in addition to the increase in (zro2) that was added to reach the highest values when the weighted percentage of 3.5% and the amount of(140h.v),(570mpa) respectively. it was noted that the ductile values are reduced continuously with the increase of the added (zro2) . the effect of particle size of (zro2) particles on the mechanical properties, it was noted that there was a little reduction in the values of hardness and tensile strength with an increase of the particle size of (zro2) bat remains higher than in the base cast and the amount of(110h.v),(210mpa) respectively. while there was an increase in the ductilevalues with increasing the particle size but they still less than in the base cast. تعتبر الكتلة الحيوية واحد al-khwarizmi engineering journal al-khwarizmi engineering journal,vol. 11, no. 2, p.p. 92-102 (2015) تشخُض انفحى انحُىٌ انًُتح يٍ خرَذ سعف انُخُم انعراقٍ ثطرَقخ انتحهم انحرارٌ ** يهُذ حسُت سهًبٌ** ايُم يحًذ رحًٍ* قبسى حسٍُ عهىاٌ * خُبٌ عجذ االيُر* اَىار شبكر *عجذ انكرَى عجذ انستبر *زَُت حسٍ عهٍ اٌٖٕبػخ ٚىاهح/ ١٘ئخ اٌجؾش ٚاٌزط٠ٛو اٌٖٕبػٟ /ِووي اٌجؾٛس اٌى١ّ١ب٠ٚخ ٚاٌجزوٚو١ّ١ب٠ٚخ * عبِؼخ ثغلاك / و١ٍخ إٌٙلٍخ اٌقٛاهىِٟ / لَُ إٌٙلٍخ اٌى١ّ١بئ١خ االؽ١بئ١خ ** dursaf1968@yahoo.com :اٌجو٠ل االٌىزوٟٚٔ* explorerxp50@yahoo.com :اٌجو٠ل االٌىزوٟٚٔ** (received 19 jun 2014; accepted 3 march 2015) انخالطخ اٌزؾًٍ اٌؾواهٞ ثّؼيي ػٓ حٍؼف إٌق١ً ثطو٠كياٌىزٍخ اٌؾ٠ٛ١خ ئٔزبط اٌفؾُ اٌؾ١ٛٞ ِٓ رؾٛي كهاٍخ ظوٚف ى ثٖٛهح فبٕخ ػٍٝاٌجؾش اٌؾبٌٟ ٠ون 523ٌٝ ػ١ٍّخ اٌزؾًٍ اٌؾواهٞ ثّلٜ رواٚػ ِٓ عهعخ اٌؾواهح ك رأص١و كهاٍخ رّذ. ٍزؼّبٌٗ وّبكح ِؾَٕخ ٌٍزوثخاْ اٌفؾُ اٌؾ٠ٛ١خ إٌبرظ ٠ّىٓ ا .األٚوَغ١ٓ اٌؼل٠ل ِٓ رُ رْق١ٔ اٌفؾُ اٌؾ١ٛٞ اٌّزىْٛ ِٓ فالي .كل١مخ/ٌزو ٠0,1زوٚع١ٓ اوبْ ِؼلي عو٠بْ غبى آٌٚكل١مخ 15ّٙٓ ىِٓ اٍزجمبء وٍفٓ 773ٜ اي ٌٚٛؽع ثبْ ،أظٙود إٌزبئظ اْ َٔجخ ِؼلي ئٔزبط اٌفؾُ اٌؾ١ٛٞ ٠مً ثي٠بكح كهعخ اٌؾواهح . اٌزؾًٍ اٌفؾٕٛبد اٌزٟ أعو٠ذ ػٍٝ اٌىزٍخ اٌؾ٠ٛ١خ ٚٔٛارظ . اٌَّبؽخ اٌَطؾ١خ َٚٔجخ ؽغُ اٌَّبِبد ٌٍفؾُ اٌؾ١ٛٞ ريكاك ثي٠بكح كهعخ اٌؾواهح ْ ٔٛػ١خ ٚو١ّخ ئ .ىكاك ثي٠بكح كهعخ اٌؾواهحدفٟ لبث١ٍخ اٌفؾُ اٌؾ١ٛٞ ػٍٝ اِزٖبٓ اٌّبء ٚاْ َٔجخ اٌّؾزٜٛ ِٓ اٌّبء ى٠بكح ٚعٛك إٌزبئظ أظٙود ا١ٍَّ١ٌٍٙٛى، )ثٖٛهح ِجبّوح ٚوج١وح ػٍٝ كهعخ اٌؾواهح ٚػٍٝ اٌزوو١جخ األٍب١ٍخ ٌٍىزٍخ اٌؾ٠ٛ١خ ِٓ اٌّووجبد رؼزّلٔٛارظ اٌزؾًٍ اٌؾواهٞ ٌٍىزٍخ اٌؾ٠ٛ١خ (. ا١ٌٍٍَٛى ٚاٌٍى١ٕٓ ٚاْ ٘نٖ اٌّغب١ِغ رقزٍف ِغ افزالف كهعبد اٌؾواهح. ٕٚف ِّزبى ٌطج١ؼخ اٌّغب١ِغ اٌفؼبٌخ اٌّٛعٛكح ػٍٝ ٍطؼ اٌفؾُ اٌؾ١ٛٞ ftirأػطذ رؾب١ًٌ (.ا١ٍَّ١ٌٍٙٛى، ا١ٌٍٍَٛى ٚاٌٍى١ٕٓ)َٚٔت اٌّىٛٔبد األٍب١ٍخ . ِؾَٕبد اٌزوثخ ،، اٌٛلٛك اٌؾftirٞٛ١اٌفؾُ اٌؾ١ٛٞ، ٔق١ً، اٌزؾًٍ اٌؾواهٞ، اي ٍؼف: انًفتبحُخ انكهًبد انًقذيخ .1 أُ٘ اؽلاٌطبلبد اٌغل٠لح ِٓ اٌىزٍخ اٌؾ٠ٛ١خ ئٔزبط٠ؼزجو ِٓ رم١ًٍ ايرٙلف اٌٝ اٌزٟ اٌؼبٌُ فٟ ٍزوار١غ١بد اٌّؼزّلح ؽب١ٌب األ هٞ ٌٍىزٍخ اٌؾ٠ٛ١خ ا٠ؼزجو اٌزؾًٍ اٌؾوٚ. ثبً اٌؾواهٞدظب٘وح االػ اٌّمزوؽخ ٌّؼبٌغخ ٘نٖ اٌظب٘وح ثّؼيي ػٓ األٚوَغ١ٓ اؽل اٌطوق ٚاٌفؾُ ( syngas)اٌٛلٛك اٌؾ١ٛٞ ٚغبىاد اٌز١ٕٖغ إلٔزبطٚ ;ondrˇej et al., 2013(a); rohan et al., 2013) اٌؾ١ٛٞ moses et al., 2011; amir et al., 2010) . ٍزؼًّ ٞؽ١ش اٌّزغلكح ادفٟ ر١ٌٛل اٌطبق اٌٛلٛك اٌؾ١ٛٞ ٚغبىاد اٌز١ٕٖغ ِٓ ٌفؾُ اٌؾ١ٛٞ ف١ؼزجو يثبٌَٕجخ أِب، (اٌؾواهح ٚاٌىٙوثبء) األٍبٍٟ ١ٌٌ وٛلٛك ٖاٍزؼّبيٚاْ اٌّٛا١ٙغ اٌّّٙخ ٚإٌبّئخ، ٢صبه آِ ٌزم١ًٍ ا اٌٛلذرؾ١َٓ فٖٛثخ اٌزوثخ ٚفٟ ٔفٌ فٟ ٚئّٔب ,.nur et al., 2013; wan et al) اد إٌّبف١خٞهاٌٍَج١خ ٌٍزغ 2013; evita et al., 2013) . أفًٚاٌزوثخ ؽ١ش رؼزجو ٍٜٚ إلىاٌخ غبىاد أفًٚ ١ٍٍٚخ ٚفٟ ٔفٌ اٌٛلذ ٌالؽزفبظ ثبٌىبهثْٛ ػٍٝ ٠ؼزّل اٌّقيْٚ اٌىوثٟٛٔ ٌٍزوثخ اْ . االؽزجبً اٌؾواهٞ ٔٛع اٌزوثخ ،أّ٘ٙب ٚأوضو٘ب رأص١واً ٟ٘ إٌّبؿ ،اٌؼٛاًِوض١و ِٓ اي ;yang et al., 2012; jonathan et al., 2011) ئكاهح اٌزوثخ suzette et al., 2011) . ِٕن ػلح ِئبد ِٓ ا١ٌَٕٓ ٚفٟ ؽٛٗ ٔٙو االِيْٚ ٚ، لل٠ّب ا٢صبه ػٍّبء لجًاٌزٟ أعو٠ذ ِٓ اٌلهاٍبد اأصجززٗٚاٌزٟ لجً اوزْبف وبٔٛا ح أْ ٍىبْ أِو٠ىب األ١١ٍٕٓ ٚاٌج١ئ ااٌغ١ٌٛٛعٟٚ اٌٝ أها١ُٙٙ اٌفؾُ اٌؾ١ٛٞ اٌمبهح األِو٠ى١خ ث١َٕٓ ػلح ١ٚ٠فْٛ رؾَٕذ ٚثٙنا ،وَّبك ٛج١ؼٟ ٠َبػل ػٍٝ رؾ١َٓ فٛآ اٌزوثخ ٚوبٔذ اٌطو٠مخ اٌزم١ٍل٠خ اٌزٟ رزجؼٙب .اٌّؾب١ًٕ اٌيهاػ١خ ٠خئٔزبط ٞ ٟ٘ عّغ ِقٍفبد ّؼٛة أِو٠ىب اٌالر١ٕ١خ ٌٖٕغ اٌفؾُ اٌؾ١ٛ إٌجبربد ٚعنٚع اٌّؾٖٛي اٌيهاػٟ ثّب فٟ مٌه األٚهاق ١ٍٚمبْ إٌبه اٚرٛلل ف١ٗفٟ ؽفوح ٚرٛٙغ ،اٌؾجٛة أٔٛاعٚلْٛه ثؼ٘ ْ رزؾًٍ ع١ّغ أؽزوق ثجٜء اٌٝ رزون ٌذّٛو ثبٌزواة ٚدصُ اٌّىٛٔبد ٚرٖجؼ ػجبهح ػٓ َِؾٛق أٍٛك اٚ ّظب٠ب ٕغ١وح ؽ١ش ٠ّىٓ اٌؾٖٛي . ٌّيهٚػبدك األهاٟٙ ٚاٞرَُرَزؼًّ فٟ ٌىزٍخ اٌؾواهٞ ي اٌزؾًٍِٓ اٌىبهثْٛ ِٓ % 50وضو ِٓ أػٍٝ ;brewer, 2012 (a); gaskin et al., 2009) األ١ٌٚخاٌؾ٠ٛ١خ steiner et la., 2008; lehmann et al., 2003;) .ًٌ ُفؾ ِىٓ أْ اٌٍٛبئً اٌزٟ ٞؽل ٠ؼزجو أ ،ِٕبفغ ػل٠لح ٌٍزوثخٌؾ١ٛٞ ا فبٌزؾًٍ اٌجطٟء ٌٍفؾُ ،اكح رأ١ً٘ األهاٟٙ اٌّزل٘ٛهحٍبػل فٟ ئعد ٕبكه اٌىبهثْٛ إٌجبرٟ فٟ اٌزوثخ ٠غؼٍٗ ِقزٍف ػٓ غ١وٖ ِٓ َ فٟ رأص١وٖ اإلعّبٌٟ ػٍٝ اٌزوثخ ٠ىّٓ ٚ، اٌؼ٠ٛٚخ فٟ اٌزوثخ فٙٛ ٠َبػل ،ٌٚٛع١خإٞٙب اٌف١ي٠بئ١خ ٚاٌى١ّ١بئ١خ ٚاٌترؾ١َٓ فٛا صج١ذ ٚرقي٠ٓ د، ًٍٙ اِزٖبٓ ٌٍّبءد ،ػٍٝ ر٠ٛٙخ اٌزوثخ mailto:dursaf1968@yahoo.com mailto:**explorerxp50@yahoo.com (2015) 92102، طفحخ 2، انعذد11دانخىارزيٍ انهُذسُخ انًدمجلة م قبسى حسٍُ عهىاٌ 93 اٌؼٕبٕو اٌغنائ١خ فٟ اٌغنٚه وّب ٠ٍؼت كٚها فٟ عنة ثؼ٘ رؾم١ك اٌزٛاىْ كافً فٟ اٌزٟ ٌٙب كٚه ٘بَ اٌّغٙو٠خاألؽ١بء فٖبثٙب ػٓ ٛو٠ك رؾ٠ًٛ ا١ٌٕزوٚع١ٓ اٌٝ ِووجبد ئاٌزوثخ ٚ ٠فؼً إٌْبٛ ،إٌجبد فٟ رى٠ٛٓ اٌجوٚر١ٓػٍّٙب ١ٔزوٚع١ٕ١خ ٠َذ ال رٛعل ثأٞ ِّٙخ ١ِيحاٌٝ ثبإلٙبفخ٘نا ، كافً اٌزوثخا١ٌّىوٚثٟ أهٗ ىهاػ١خ أفوٜ ثبٌؼبٌُ اال فٟ ِٕطمخ األِيْٚ ٟٚ٘ إٌَت غبى صبٟٔ أٚو١َل اٌىوثْٛ ِغ ِٓ َٔتاياٌم١ٍٍخ ٔجؼبصبد اال ِٓ اٌىض١و روكٞٚ٘نا ال ٠ؼٕٟ اْ .) ٠ىوٚثٟاَائْبٛ اٌؼب١ٌخ ِٓ اي ِْجؼخ ٚٔٙب ن ْع اٌجؼل وً ثؼ١لح أٔٙب اٌغبفخ األهاٟٙ روثخ wan) علا ػب١ٌخ ٌٍىوثْٛ ػيٌٙب ئِىب١ٔخ رىْٛ لل ئم ثبٌىوثْٛ، et al., 2013; marion et al., 2012; wei et al., 2010). ٠ّىٓ اْ رمًٍ ثّملاه اٌؾواهٞ ثبًداالػ غبىاد أجؼبصبد ئْ األهٗ فٟ اٌؾ١ٛٞ اٌفؾُػّبي ػٕل اٍذ ِواد فٌّ ٚا ِور١ٓ اٌىوثْٛ رغلك إٌٙظ ٘نا ِىبْثا ٠ىْٛ إٌؾٛ، ٘نا ٌٝع. اٌيهاػ١خ إٌّبؿ، ٌزغ١و ثبٌَٕجخ ٘بِخ رى١ف اٌؼًّ وأكاح اٌزوثخ،فٟ اٌؼٚٛٞ junyeong et al., 2013; sohi) اٌىوثْٛ رضج١ذ ئٌٝ ئٙبفخ et al., 2010;) . ثْىً الٔزبط اٌفؾُ اٌؾ١ٛٞ اٌَّزؼٍّخٔٛع اٌىزٍخ اٌؾ٠ٛ١خ ؤصو ٞ ظوٚف اٌزؾًٍ ٚرؼزجو ، إٌّزظػٍٝ فٖبئٔ اٌفؾُ وج١و ٔٛػ١خ ثَجت رأص١و٘ب ػٍٝ ٚرأص١وا ٚمٌه أ١ّ٘خ اٌؾواهٞ األوضو . اٌزوثخ ٠خٍزمواها٠َبُ٘ فٟ مٞاي إٌّزظ اٌؾ١ٛٞٚو١ّخ اٌفؾُ أٔٛاع اٍزؼًّ ف١ٙب اٍزّود ٌّلح ػب١ِٓ ٚمٌه ؽَت اٌلهاٍخ اٌزٟ ِلٜ ٚي، كهعبد اٌؾواهحكٜ ِٓ ٌُٚ ،اٌىزٍخ اٌؾ٠ٛ١خِقزٍفخ ِٓ د ِقزٍفخ ٌوفغ ِٚؼلالاٌّبكح األ١ٌٚخ اٍزجمبء أىِٕخٚاٍغ ِٓ ,ondrˇej et al., 2013(b); kaige et al) كهعبد اٌؾواهح 2013; shane et al., 2013; weiping et al., 2013; zhengang et al., 2013; brewer, 2012 (b); ) . فجبألِبوٓ رطج١مٙب ثألً ٍزوار١غ١خ ِٓ إٌبؽ١خ اٌزم١ٕخ اٚن ِٕبعُ أٚ ايأٍفً آثبه إٌفٜ أٚ co2ٙـ ػ١ٍّخ ك٠بد ِمبهٔخ ةاٌزؼ ٚر١ْو اٌؾَبثبد األ١ٌٚخ . فٟ رغن٠خ اٌّؾ١طبد ثبٌّٛاك اٌى١ّ١بئ١خ : ِٓ األهاٟٙ اٌيهاػ١خ اٌّزٛفوح فٟ اٌؼبٌُ 2,5أٔٗ ئما اٍزؼًّ ٚاٍزؼّبٌٗ فٟ (ثْىً اِضً ِٓ إٌفب٠بد) اٌؾ١ٛٞاٌفؾُ إلٔزبط اد صبٟٔ أو١َل اٌىوثْٛ فٟ اٌغالف روثخ لل ٠زُ فف٘ َِزٛٞاي esben et) 2050ثؾٍٛي ػبَ 1752اٌغٛٞ ئٌٝ ِب لجً ػبَ al., 2012; daniele et al., 2012; dorisel et al., 2011). إٌّظّبد غ١و اٌؾى١ِٛخ ٚا١ٌٙئبد اٌجؾض١خ ٕ٘بٌه اٌؼل٠ل ِٓ اٌقٚو فٟ ع١ّغ أٔؾبء اٌؼبٌُ ِٙزّْٛ علا ثبٌفؾُ اّط١ٓ ْايٚ ئػبكح ،رؾ١َٓ اٌزوثخ، ئكاهح إٌفب٠بد، ئٔزبط اٌطبلخ ِٓ أعً اٌؾ١ٛٞ . رأ١ً٘ األهاٟٙ اٌّزل٘ٛهح ٚاٌزقف١ف ِٓ آصبه رغ١و إٌّبؿ . ٚاٍزؼّبٌٗ اٌؾ١ٛٞاٌفؾُ ئٔزبطثؼُٚٙ افن ػٍٝ ػبرمٗ ِؾبٚالد ػيىد ارفبل١خ األُِ اٌّزؾلح ٌّىبفؾخ اٌزٖؾو اٍزؼّبي اٌفؾُ ونٌه brewer, 2012; marion) ٌّٞٗىبفؾخ رل٘ٛه األها اٌؾ١ٛٞ et al., 2012; rodrigo et al., 2012) . اٌىزٍخ اٌؾ٠ٛ١خ فٟ أٌٍٛ ِٖبكه فٟ إٌٙل اٌؼًّ عبه ٌز١ٍٛغ اٌّؾزٍّخ ؽ٠ٛ١خ اياٌىزٍخ و١ّبد اٌّٛاهك ا١ٌٕٛٛخ ٌٍزؾمك ِٓ . (brewer, 2012 a) اٌؾ١ٌٛٞفؾُ فٟ ئٔزبط اٚاٌَّزؼٍّخ ؽب١ٌب ك٘ب لبكهح ػٍٝ ئٔزبط و١ّبد رىْٛ ٚػ ِٓ اٌّإًِ اْاٌجواى٠ً فٟ األهاٟٙ اٌزٟ رُ رط١ٙو٘ب ػّبيوج١وح ِٓ اٌٛلٛك اٌؾ١ٛٞ ثبٍذ ِٓ فالي ىهاػخ ػْت ٔبة اٌف١ً اٌّزوٚوخ،ٚاألهاٟٙ miscanthus ٘نا إٌجبد ثّٕٖٛ اٌَو٠غ ٚاٌىج١و ؽ١ش ٠ّزبى ِؾب١ًٕ أُ٘ ٠ِٓؼل فٖٙٛ اٌغي٠و ِٓ اٌّبكح اٌغبفخ، ٚئٔزبط اٌفؾُ ٚ هئ١َٟوّٕزظ اٌؾ١ٛٞ اٌٛلٛك إلٔزبط ػًّاٌزٟ رَذ اٌطبلخ اٌطؾبٌت ٍزؼّبي فٟ إٚ٘بن اؽزّبي آفو .وّٕزظ صبٔٛٞاٌؾ١ٛٞ فٟ اٌجؾ١واد أٚ اٌّفبػالد اٌؾ١ٛٞ ٔزبط اٌفؾُ إلوزٍخ ؽ٠ٛ١خ ن ,.rohan et al) ١ِبٖ ماد ٔٛػ١خ هك٠ئخ ثبٍزؼّبياٌؾ٠ٛ١خ 2013; kaige et al., 2013; brewer, 2012 a). ِٓ ٔفب٠بد اٌؾ١ٛٞاٌفؾُ فٟ عيه اٌّبٌل٠ف ٕ٘بن فطٜ إلٔزبط اٌّؾب١ًٕ اٌيهاػ١خ ِٚيعٙب ِغ ٔفب٠بد األٍّبن ٚثبٍزؼّبي اٌؾ١ٛٞٚاٌفؾُ اٌز١ٕٖغغبىاد إلٔزبط ٚؽلاد اٌزؾًٍ اٌؾواهٞ ,brewer) اٌطبلخ ؽ١َٓ اٌزوثخ، ٚاٌؾل ِٓ رىب١ٌفدالٍزؼّبٌٗ فٟ 2012a) . ؽ١َٓاٌؾ١ٛٞ ٌذفٟ أٍزوا١ٌب وبٔذ ٕ٘بن رغبهة ٚاػلح ِغ اٌفؾُ ؽمٛي األهى فٟ فٟ ٚمٌه ِٓ فالي اٍزؼّبٌٗ اٌزوثخ اٌفم١وح ٔزبط اٌّؾب١ًٕ إلِؼلالد ؽ١ش ٍغٍذ أػٍٝ اي ،ِورفؼبد اًٚ إٌزوٚع١ٕ١خ ٌألٍّلحاالٍزغبثخ فٟ اٌيهاػ١خ، ٚ رؾَٓ .ٚاٌفٍٛفبر١خ ثلأد اٌزغبهة ا١ٌّلا١ٔخ ٠ٍٛٛخ ،2009فٟ ١ٔٛ٠ٛ فٟ أىٍزوا، ػٍٝ ث١ٕخ اٌزوثخ ٚاؽزجبً اٌّبء رأص١وٌٖزم١١ُ اٌؾ١ٛٞ األِل ِغ اٌفؾُ ْ ل١ّخ اٌفؾُ ئرج١ٓ ئم . rothamsteadِؾطخ اٌزغو٠ج١خ ايفٟ ٌؾ١ٛٞ ٕ٘بٌه ِإّواد ػٍٝ اْ ئٙبفخ اٌفؾُ اٚٚاػلح، اٌؾ١ٛٞ arbuscular mycorrhizal اٌفطو٠بد ِٓ ٔٛع ٠ؾفي فؼب١ٌخ ,joseph et al., 2010; mchenry) اٌّٛعٛك فٟ اٌزوثخ 2009). هد اٌزغبهة اٌّقزجو٠خ ٚاٌؾم١ٍخ اٌزٟ أعو٠ذ ػٍٝ أظٗ فٟ وض١و ِٓ اٌؼٕبٕو اٌّغن٠خاٌّؾزٜٛ اٌم١ًٍ ِٓ األروثخ ماد ، ى٠بكح فٟ ِؼلي ئٔزبط اٌّؾب١ًٕ اٌلهاٍبد اٌّٛصمخ فٟ اٌّٖبكه ال ِٖٚغ مٌه، فبْ رأص١و. اٌؾ١ٛٞاٌفؾُ اٌيهاػ١خ ٔز١غخ الٍزؼّبي اٌزأص١و اٌم١ًٍ اٚ غ١و ؽبٍُ، ؽ١ش وْفذ كهاٍبد أفوٜ ٠ياي ؽب١ٌب، ١ِىب١ٔى١خ . فؾُ إٌجبرٟاٌؾ١ٛٞ ِمبهٔخ ثبياٌٍَجٟ ٌٍفؾُ ٚرأص١وٖ ػٍٝ فٖبئٔ اٌزوثخ غ١و اٌؾ١ٛٞا١ٌَطوح ٚأزمبي اٌفؾُ ثَجت ِفِٙٛخ ثٛٙٛػ ػالٚح ػٍٝ مٌه ِٓ اٌٖؼٛثخ ِمبهٔزٙب ، ؽ١ٛٞايفؾُ اي، اٌَّزؼٍّخ روثخاي، اٌىض١و ِٓ االفزالفبد ِٕٙب اٌـ ِٓ االفزالفبد ث١ٓ ...، إٌّبؿ، ِٕٚٙغ١خ اٌجؾش،ٌؾ٠ٛ١خاٌىزٍخ ا ادِٚغ مٌه، ثلْٚ اٌجؾش ٚاٌؾنه اٌىبفٟ فٟ اٌزطج١ك .اٌلهاٍبد ٠ّىٓ أْ رىْٛ ٕ٘بن ِٖٚبكه اٌىزٍخ اٌؾ٠ٛ١خ اإلٔزبطٚفٟ ٛوق rodrigo) اٌؾ١ٛٞأٚ رإفو ر١ّٕخ اٌفؾُ ِْٖٚبوً، ٚاٌزٟ لل رِ et al., 2012; ferrante et al., 2011; mandu et al., 2010; wei et al., 2010) . ػ٠ٛٚخ ٚثؼ٘ اٌّٛاك اٌجالٍز١ى١خ ٠ّىٓ اٍزؼّبٌٙب ِبكح اْ أٞ ، ثّب فٟ مٌه إٌفب٠بد فٟ إٌّبٛك اٌو٠ف١خ، ٚإٌفب٠بد أ١ٌٚخوّبكح اٌؾ١ٛأبد ٚفٚالداٌيهاػ١خ ٚاٌٖٕبػ١خ ٚاٌٖوف اٌٖؾٟ اٌّبٌؾخ أٚ ا١ٌّبٖ . ٚاٌطؾبٌت اٌّبئ١خ، ٚإٌجبربد اٌّبئ١خ ٚغ١و٘ب اٌٍّٛصخ اٌزٟ ال رٍٖؼ ٌيهاػخ اٌّؾب١ًٕ اٌغنائ١خ لل رلػُ ئٔزبط إٌق١ً )اٌطؾبٌت أٚ إٌجبربد اٌزٟ رزؾًّ اٌٍّٛؽخ اٌؼب١ٌخ ، ِٚقزٍف إٌجبربد mangroves ٚاٌمٖت، ٚأّغبه اٌّبٔغوٚف weiping et) اٌؾ١ٛٞاٌفؾُ إلٔزبطاٌزٟ رَزؼًّ ( اٌـ ...اٌٍّؾ١خ al., 2012; suzette et al., 2011; janathan et al., 2011; moses et al., 2011) . افن اٌؾ١ٛٞاال٘زّبَ ثبٌفؾُ ط ِّب ٍجك ػوٙٗ اْ دَٔزٓ ٠ٚجلٚ ِٓ . إلٔزبعٗاٌٖٕبػ١خ َِبهٖ ٚ ٠غوٞ رٕف١ن اٌّْبه٠غ ٌٝ رجبكي ٠ّىٓ أْ ٠ؾَٓ للهح اٌزوثخ ع اٌؾ١ٛٞاٌّوعؼ أْ اٌفؾُ اٌىزٍخ اٌؾ٠ٛ١خ ٚا١ٙغ وٍٙب رؾلك٘ب ٔٛػ١خ ، ٚ٘نٖ اٌُاأل٠ٛٔبد أ٠ٚب . اٌزٟ رَزؼًّ إلٔزبط اٌفؾُ اٌؾ١ٛٞ كهاٍخ ئٔزبط اٌفؾُ اٌؾ١ٛٞ ِٓ ٍؼف ٠ٙلف اٌؼًّ اٌؾبٌٟ اٌٝ ثؾش فٟ اي .إٌق١ً وىزٍخ ؽ٠ٛ١خ ثبػزجبه٘ب ِبكح ِزٛفوح ِؾ١ٍب رُ رْق١ٔ اٌفؾُ اٌؾ١ٛٞ ١ٌّىٓ ِٓ اٍزؼّبٌٗ ٌألغواٗ اٌؾبٌٟ رم١ًٍ ؽغُ )ٌٚألغواٗ اٌج١ئ١خ ( ٔزبع١خ اٌزوثخرؾ١َٓ ئ)اٌيهاػ١خ اعو٠ذ اٌزغبهة فٟ كهعبد ؽواهح رزواٚػ (. اٌٍّٛصبد فٟ اٌزوثخ ، ٚثبٍزؼّبي غبى إٌزوٚع١ٓ ٌطوك وٍفٓ 773اٌٝ 523ث١ٓ ثؼ١ٍّخ ؽ١ش اٌٚغٜ اٌغٛٞ ٘ٛ اٌٚغٜ اٌَّزؼًّ األٚوَغ١ٓ http://ar.wikipedia.org/wiki/%d9%88%d9%82%d9%88%d8%af_%d8%ad%d9%8a%d9%88%d9%8a http://ar.wikipedia.org/wiki/%d9%88%d9%82%d9%88%d8%af_%d8%ad%d9%8a%d9%88%d9%8a http://ar.wikipedia.org/wiki/%d9%88%d9%82%d9%88%d8%af_%d8%ad%d9%8a%d9%88%d9%8a http://ar.wikipedia.org/wiki/%d9%88%d9%82%d9%88%d8%af_%d8%ad%d9%8a%d9%88%d9%8a http://ar.wikipedia.org/wiki/%d9%88%d9%82%d9%88%d8%af_%d8%ad%d9%8a%d9%88%d9%8a http://ar.wikipedia.org/wiki/%d9%88%d9%82%d9%88%d8%af_%d8%ad%d9%8a%d9%88%d9%8a (2015) 92102، طفحخ 2، انعذد11دانخىارزيٍ انهُذسُخ انًدمجلة م قبسى حسٍُ عهىاٌ 94 ثبٍزؼّبي ِٕظِٛخ رفبػً اعو٠ذ اٌزغبهة .اٌزؾًٍ اٌؾواهٞ اٌغو٠بْ اٌَّزّو ٌٍغبى اٌؾبًِ ٚٔٛع اٌؾْٛح اٌضبثزخ رجو٠خ ِـ (. وغبى ؽبًِ إٌزوٚع١ٓاٍزؼًّ غبى ) اندسء انعًهٍ .2 وانطرق انًىاد 2-1 األونُخ انًبدح 2-1-1 ٚثبٌزؾل٠ل عو٠ل اٌَؼف، اِؾٍٟاٌّزٛفو اٍزؼًّ ٍؼف إٌق١ً ِقزجو رُ ؽفع ٍؼف إٌق١ً فٟ اي. اٌؾ١ٛٞوّبكح أ١ٌٚخ إلٔزبط اٌفؾُ . فٟ رؾ١ٚو اٌىزٍخ اٌؾ٠ٛ١خالٍزؼّبٌٗ ثلهعخ اٌؾواهح االػز١بك٠خ انغبزاد 2-1-2 ١ٕٕٟ %( 99,999)اٍزؼًّ غبى إٌزوٚع١ٓ ثٕمبٚح ػب١ٌخ اٌزغبهة وغبى ؽبًِ فٟ ،عٙي ِٓ األٍٛاق اٌّؾ١ٍخٚاٌُاٌٖٕغ . ٌطوك األٚوَغ١ٓ ِٓ ِفبػً اٌزؾًٍ اٌؾواهٞٚاٌّقزجو٠خ نعًهُخ انحُىَخ تحضُر انكتهخ 2-2 373ف ٍؼف إٌق١ً ٌّلح ٠َٛ ٚاؽل ثلهعخ ؽواهح ٞعفرُ د ثبٍزؼّبي فوْ رغف١ف ِٚٓ صُ ٛؾٓ ثبٍزؼّبي ٛبؽٛٔخ ٔٛع وٍفٓ (herbal medicine grinding machine ) ٍبػخٌّٚلح . ثؼل٘ب رُ ٔقً إٌبرظ ٌٍؾٖٛي ػٍٝ اٌّمطغ اٌنٞ رواٚػ ؽغُ عواء فٟ ئاٌنٞ اػزّل ٍُِٚ 2,36ئٌٝ ٍُِ 1اٌغ١َّبد ف١ٗ ِٓ . اٌزغبهة اٌّقزجو٠خ رُ ؽفع اٌى١ّبد اٌّطٍٛثخ ِٓ ِمطغ ٍؼف إٌق١ً اٌّطؾْٛ فٟ عٙبى اٌزغف١ف اٌيعبعٟ ٚثلهعخ ؽواهح اٌغوفخ االػز١بك٠خ ٠ج١ٓ ( 1)اٌغلٚي هلُ . ٌزىْٛ ١ِٙأح إلعواء اٌزغبهة اٌّقزجو٠خ . ؽٌّْٛمطغ ٍؼف إٌق١ً اٌّٜٚاٌى١ّ١ب٠ٚخ اٌقٛآ اٌف١ي٠ب٠ٚخ ( 1)اندذول رقى . انخىاص انفُسَبوَخ نًقطع سعف انُخُم 0.618 surface area, (m 2 /g) nil pore volume, (cm 3 /g) 3.432 water content at 383k, 2hr (wt.%) 63.24 loss on ignition at 623k, 1hr (wt.%) 2.5% ash content, (%) at 1073k (3hr) حرارٌ انًختجرَخ نتحهم الايُظىيخ 2-3 أعو٠ذ رغبهة اٌزؾًٍ اٌؾواهٞ فٟ ٚؽلح اٌزفبػً اٌّقزجو٠خ . اٌزٟ رؾزٛٞ ػٍٝ ِفبػً مٚ اٌؾْٛح اٌضبثزخ ٚاٌغو٠بْ اٌَّزّو رزىْٛ ٘نٖ . ٠ّضً ِقطٜ ِٕظِٛخ اٌزؾًٍ اٌؾواهٞ( 1)اٌْىً هلُ عٙبى ل١بً ( 2)اٍطٛأبد غبى إٌزوٚع١ٓ، ( 1)إٌّظِٛخ ِٓ ( 4)ٚؽلح رَق١ٓ غبى إٌزوٚع١ٓ، ( 3)ِؼلي عو٠بْ اٌغبى، ٚؽلح ( 6)ٚؽلح رىض١ف اٌغبىاد ( 5)ِفبػً اٌزؾًٍ اٌؾواهٞ، ١ِٖلح اٌغبىاد غ١و اٌمبثٍخ ٌٍزىض١ف ( 7)رغ١ّغ اٌغبىاد اٌّزىضفخ، اٌؾبٍجخ ( 9)عٙبى اٌزجو٠ل، ( 8)ثبٍزؼّبي إٌزوٚع١ٓ اٌَبئً، عبد ٘نا ثبإلٙبفخ اٌٝ عٙبى اٌزؾىُ ثله( 10)اٌىزو١ٔٚخ ، kاٌؾواهح ٌٍّفبػً ٚٚؽلح اٌزَق١ٓ ٚثبٍزؼّبي ِزؾََبد ٔٛع (ts1 & ts2 .) ّّٕٓذ اٌَّقٕبد اٌّٛعٛكح فٟ ٚؽلح اٌزَق١ ٚاٌّفبػً ٌوفغ كهعخ اٌؾواهح اٌٝ اٌلهعخ اٌّطٍٛثخ فالي فزوح . ى١ِٕخ ل١ٖوح ال رزغبٚى اٌوثغ ٍبػخ تدبرة انتحهم انحرارٌ 2-4 غُ ِٓ ِمطغ ٍؼف إٌق١ً 20لجً اٌجلا ثبٌزْغ١ً ٠زُ ٚٙغ ِٚٓ صُ ٠ؾىُ غٍك ( ٌزو 1ؽغُ )فٟ ِفبػً اٌزؾًٍ اٌؾواهٞ كل١مخ ِٓ غبى إٌزوٚع١ٓ اٌٝ / ٌزو 0,1اٌّفبػً، ثؼل٘ب ٠ّوه ِٕظِٛخ اٌزفبػً ثؼل ل١بٍٗ ثغٙبى ل١بً ِؼلي عو٠بْ اٌغبى، ٚمٌه ٠زُ رَق١ٓ غبى . ٌطوك األٚوَغ١ٓ اٌّٛعٛك فٟ إٌّظِٛخ ح ٚؽلح اٌزَق١ٓ ١ٌلفً اٌٝ اٌّفبػً ثلهعخ إٌزوٚع١ٓ ثٛاٍٜ ؽواهح اٌّفبػً ػٓ ٛو٠ك اٌَّقٕبد اٌىٙوثبئ١خ، ؽ١ش ٠زُ kا١ٌَطوح ػٍٝ كهعخ اٌؾواهح ثبٍزؼّبي ِزؾََبد ِٓ ٔٛع ٚػٓ ٛو٠ك ٚاعٙخ اٌزطج١ك اٌقبٕخ ثبٌجؤبِظ اٌّؼلح ٌٙنا اٌغوٗ رَزغوق ػ١ٍّخ اٌزَق١ٓ . ٚاٌّٛعٛكح فٟ اٌىّج١ٛرو اٌّؾّٛي كل١مخ ٚػٕل إٌٛٛي 15ٚي اٌٝ كهعخ اٌؾواهح اٌّطٍٛثخ ٌٍٛٓ اٌٝ اٌلهعخ اٌّطٍٛثخ ٠زُ اؽزَبة ىِٓ اٍزجمبء اٌّبكح األ١ٌٚخ فٟ ٠لفً غبى إٌزوٚع١ٓ اٌَبفٓ ٚاٌمبكَ ِٓ ٚؽلح اٌزَق١ٓ . اٌّفبػً اٌٝ ِفبػً اٌزؾًٍ ِٓ األػٍٝ ٚمٌه ٌّٚبْ رٛى٠ؼٗ ثٖٛهح ْٚ اٌمٕٛاد اٌقب١ٌخ ِٓ ِٕزظّخ فالي َِبؽخ اٌّمطغ ٌٚزالفٟ ره ٠َزّو عو٠بْ غبى إٌزوٚع١ٓ فالي اٌّفبػً ثْىً ٛجمٟ . اٌغبى ِٕٚزظُ ٚفالي اٌؾْٛح اٌضبثزخ ِٓ اٌىزٍخ اٌؾ٠ٛ١خ اٌّٛٙٛػخ فٟ ٠زُ . ٍٍخ ِّّٖخ ٌٙنا اٌغوٗ، ؽ١ش رزؾًٍ ثّؼيي ػٓ اٌٙٛاء ٍؾت ٔٛارظ اٌزفبػً ِٓ أٍفً اٌّفبػً ػٍٝ ّىً غبىاد ٞ اٌّوؽٍخ اٌالؽمخ فًٖ اٌغبىاد اٌمبثٍخ ٚاٌمطواْ، ؽ١ش ٠زُ ف ٌٍزىض١ف ٚاٌَٛائً ػٓ اٌغبىاد غ١و اٌمبثٍخ ٌٍزىض١ف ثٛاٍطخ ِىضف وٍفٓ ِٚٓ صُ رؾفع اٌّٛاك 269ىعبعٟ ؽ١ش كهعخ ؽواهرٗ 269اٌّزىضفخ ػٍٝ ّىً ٍبئً فٟ ٚؽلح اٌزغ١ّغ ثلهعخ ؽواهح لخ ٠زُ ثبٌَٕجخ ٌٍغبىاد غ١و اٌمبثٍخ ٌٍزىضف ثبٌظوٚف اٌَبة. وٍفٓ رّو٠و٘ب فالي ٚؽلح ١ِٖلح اٌغبىاد اٌزٟ رؾزٛٞ ػٍٝ ٍبئً فٟ ٔٙب٠خ . إٌزوٚع١ٓ، ؽ١ش ٠زُ رىض١ف ٚاؽزغبى اٌغبىاد ٚؽفظٙب وً رغوثخ رغّغ إٌٛارظ اٌٍٖجخ ٚاٌَبئٍخ ٚاٌغبى٠خ إلعواء اٌزؾب١ًٌ فٟ ٘نٖ . اٌّطٍٛثخ ٌّؼوفخ ٔٛػ١خ ٚو١ّخ اٌّٛاك اٌّٛعٛكح ف١ٙب ٚف اٌزب١ٌخ، كهعخ اٌؾواهح رواٚؽذ ِٓ اٌزغبهة افز١ود اٌظو كل١مخ، /ٌزو 0,1وٍفٓ، ِؼلي عو٠بْ غبى إٌزوٚع١ٓ 773 – 523 كل١مخ، ؽ١ش وبْ اٌٚغٜ اٌَّزؼًّ اٌٚغٜ 30ٚىِٓ اٍزجمبء . اٌغٛٞ االػز١بكٞ انتحبنُم انًختجرَخ 2-5 اعو٠ذ اٌؼل٠ل ِٓ اٌزؾب١ًٌ اٌّقزجو٠خ ٌٍغبىاد ٚاألثقوح ثٖٛهح ػبِخ . ما ثبإلٙبفخ اٌٝ اٌفؾُ اٌؾ١ٛٞٚاٌَٛائً اٌّزىضفخ ٖ : ٠ّىٓ رم١َُ اٌزؾب١ًٌ اٌٝ األلَبَ ا٢ر١خ gcتحبنُم خهبز 2-5-1 gcرؾب١ًٌ اٌّبكح اٌَبئٍخ ٚاٌغبى٠خ أعو٠ذ ثبٍزؼّبي عٙبى ، اٌّٛعٛك فٟ (gc-2014a)ِٛك٠ً ( schimadzu)ٔٛع . كائوح اثٓ اٌج١طبه ftirتحبنُم خهبز 2-5-2 إٌٛع ِٓ اٌزؾب١ًٌ، أعو٠ذ اٌزؾب١ًٌ ٌٍّٛاك اٌَبئٍخ فٟ ٘نا ٚاٌٍٖجخ ٌّؼوفخ ٔٛػ١خ اٌّووجبد اٌّٛعٛكح فٟ ٔٛارظ اٌزفبػً ٚمٌه ٌزم٠ُٛ ػ١ٍّخ اٌزؾًٍ اٌؾواهٞ ٌٍىزٍخ اٌؾ٠ٛ١خ ِٓ ٍؼف (2015) 92102، طفحخ 2، انعذد11دانخىارزيٍ انهُذسُخ انًدمجلة م قبسى حسٍُ عهىاٌ 95 ِٛك٠ً ( ftir bruker)ؽ١ش اعو٠ذ فٟ عٙبى . إٌق١ً (tensor 27 )فٟ كائوح اثٓ اٌج١طبه. وحدى انًسبيبد انًسبحخ انسطحُختحبنُم 2-5-3 رُ ئعواء ٘ن٠ٓ اٌفؾ١ٖٓ فٟ ِووي اٌجؾش ٚاٌزط٠ٛو إٌفطٟ اٌزٟ رؼزّل ػٍٝ astm d1993ٚثبٍزؼّبي ٛو٠مخ اٌفؾٔ رُ فؾٔ اٌَّبؽخ اٌَطؾ١خ ٚؽغُ اٌغ١َّبد ٌٍىزٍخ . betٛو٠مخ . اٌؾ٠ٛ١خ، ٌٍٚفؾُ اٌؾ١ٛٞ إٌبرظ ِٓ وً رغوثخ انُتبئح ويُبقشتهب .3 َر درخخ انحرارح تأث 3-1 تأثُر درخخ انحرارح عهً َسجخ إَتبج انفحى انحُىٌ 3-1-1 ٠ٛٙؼ اٌؼاللخ ث١ٓ َٔجخ ئٔزبط اٌفؾُ اٌؾ١ٛٞ ِغ ( 2)اٌْىً هلُ ٔالؽع اْ َٔجخ ئٔزبط اٌفؾُ اٌؾ١ٛٞ رمً ِغ اٌي٠بكح . كهعخ اٌؾواهح اْ ٘نا . فٟ كهعخ ؽواهح اٌزفبػً ٠ّٚىٓ اٌمٛي ثبْ اٌؼاللخ فط١خ ٌزٖوف ٠ّىٓ ئ٠ؼبىٖ ئٌٝ اٌزؾًٍ اٌؾواهٞ اٌىج١و اٌنٞ رزؼوٗ ا ٌٗ روو١جخ اٌىزٍخ اٌؾ٠ٛ١خ ِغ اٌي٠بكح فٟ كهعخ ؽواهح اٌزفبػً ٚ٘نٖ ondřej et)اٌظب٘وح لل ٌٛؽظذ فٟ اٌؼل٠ل ِٓ اٌلهاٍبد اٌَبثمخ al., 2013; weiping et al., 2012; marion et al., 2012; esben et al., 2012; ferrante et al., 2011 .) : ٠زىْٛ ٍؼف إٌق١ً ِٓ اٌّووجبد اٌوئ١َ١خ اٌضالس ا٢ر١خ < ٚاْ َٔجخ اٌّووجبد ا١ٌٍٍَٛى٠خ. ا١ٍَّ١ٌٍٙٛى، ا١ٌٍٍَٛى ٚاٌٍى١ٕٓ hassan et al., 2088; ashwaq et)اٌٍى١ٕٓ < ا١ٍَّ١ٌٍٙٛى al., 2006 .) ٜٚر١ْو اٌلهاٍبد ئٌٝ اْ ا١ٍَّ١ٌٍٙٛى ٠زؾًٍ ثبٌّل وٍفٓ ِٓ كهعبد اٌؾواهح ث١ّٕب ا١ٌٍٍَٛى ٚاٌٍى١ٕٓ 513ئٌٝ 453 وٍفٓ ػٍٝ 443 -433وٍفٓ ٚ 583ئٌٝ ٠503زؾٍالْ ثبٌّلٜ ٌٚٙنا (. wei et al., 2010; sohi et al., 2010)اٌزٛاٌٟ ٠ّىٓ اٌمٛي ثبْ اٌزؾًٍ ٠غوٜ ػٍٝ ِواؽً ٚفٟ وً كهعخ ؽواهح ؽع االٔقفبٗ ٠زُ اٌزؼبًِ ِغ ِبكح ١٘لهٚوبهث١ٔٛخ عل٠لح ٚثٙنا ٔال . ث١و فٟ َٔجخ ئٔزبط اٌفؾُ اٌؾ١ٛٞاٌه . انًخطظ انعبو نًُظىيخ انتحهم انحرارٌ نهكتهخ انحُىَخ انًختجرَخ( 1)شكم رقى 1 n2 gas cylinder. 7 liquid nitrogen trap. 2 n2 gas flow meter. 8 gas pressure regulator. 3 pre-heater for nitrogen gas. 9 temperature controller . 4 pyrolysis reactor. 10 laptop 5 gas condenser. ts1,2 temperature sensors 6 liquid collector. 9 0 0 9 9 9 2 2 3 to gas chromatography gc 7 7 7 6 6 5 5 5 8 8 ُ 3 3 t s 1 4 4 ts 2 ts1 10 99 ts2 1 1 (2015) 92102، طفحخ 2، انعذد11دانخىارزيٍ انهُذسُخ انًدمجلة م قبسى حسٍُ عهىاٌ 96 10 20 30 40 50 60 70 80 450500550600650700750800 درجت الحرارة )كلفن( )% ( ر، ض خ أل ا حم لف ا ج تا إن ت سب ن درخخ و انحُىٌَسجخ إَتبج انفحى ًَثم انعالقخ ثٍُ ( 2)انشكم رقى 0,1دل خرَبٌ غبز انُتروخٍُ دقُقخ ويع 15زيٍ انتفبعم ) انحرارح . (دقُقخ/نتر ٌ رَىاتح انتحهم انحراتأثُر درخخ انحرارح عهً 3-1-2 ٚعٛك ػلك وج١و ِٓ gcٌٛؽع ِٓ فالي رؾب١ًٌ عٙبى ٌُ ٠زُ ا٢فواٌّٛاك ا١ٌٙلهٚوبث١ٔٛخ ثؼٚٙب رُ رْق١ٖٗ ٚاٌجؼ٘ اْ ٔٛػ١خ َٚٔت اٌّٛاك ا١ٌٙلهٚوبهث١ٔٛخ . اٌزّىٓ ِٓ رْق١ٖٗ ّىً ثبي اعخ ِٓ اٌزؾًٍ اٌؾواهٞ ٌٍىزٍخ اٌؾ٠ٛ١خ ٠ّىٓ ر١ٙٛؾٗإٌبد ِٓ اٌّٛاك حِغّٛعإٌَت اٌؼب١ٌخ يافز١به رُ (. 3)هلُ ِٚؼلي رٛاعل٘ب ٌٍّلٜ اٌّؾلك ِٓ كهعبد ا١ٌٙلهٚوبهث١ٔٛخ .اٌؾواهح ٔالؽع رغ١و َٔت اٌّٛاك ا١ٌٙلهٚوبهث١ٔٛخ ِغ افزالف كهعبد اٌؾواهح ٌزأص١و اٌؼبٌٟ ٌلهعخاٌؾواهح، ٠ٚؼيٜ ٘نا االفزالف ئٌٝ ا ٚروو١جخ اٌىزٍخ اٌؾ٠ٛ١خ ثؾَت ِب ٠ْبه ا١ٌٗ فٟ وض١و ِٓ اٌلهاٍبد ;junyeong et al., 2013; ondřej et al., 2013)اٌَبثمخ evita et al., 2013; steven et al., 2012; weiping et al., 2012; wei et al., 2010; sohi et al., 2010 .)ْئ َٔجخ اٌّٛاك ا١ٌٙلهٚوبهث١ٔٛخ ٠وعغ ئٌٝ رغ١و ٔٛػ١خ ٚاالفزالف ا١ٍَّ١ٌٍٙٛى، ا١ٌٍٍَٛى )َٔت اٌّىٛٔبد األٍب١ٍخ ٌَؼف إٌق١ً ٚونٌه ئٌٝ ٔٛع اٌىزٍخ ِغ افزالف كهعخ اٌؾواهح( ٚاٌٍى١ٕٓ ٌٚىً ِبكح ِٓ ٘نٖ اٌّٛاك رؼطٟ ِؼلالد اٌؾ٠ٛ١خ فٟ رٍه اٌلهعخ ٔالؽع ّٙٓ . .ألفوٜرقزٍف ػٓ اٌّبكر١ٓ ا اٌؾ١ٛٞئٔزبط ٌٍفؾُ اْ وٍفٓ، 573ٌٚغب٠خ وٍفٓ 523اٌّلٜ ِٓ كهعبد اٌؾواهح اْ اٌىزٍخ اٌؾ٠ٛ١خ اٌزٟ رزؾًٍ ثّؼلالد ػب١ٌخ ٟ٘ ػجبهح ا١ٍَّ١ٌٍٙٛى هاٚػ ِٓ اٌجوٚثبْ دٚر١ًّ ئٌٝ رى٠ٛٓ ِووجبد ِْجؼخ َِزم١ّخ د وجبد ريكاك ثي٠بكح كهعخ ئٌٝ اٌٙجزبْ االػز١بكٞ ٚاْ َٔجخ ٘نٖ اٌّو ئٌٝ وٍفٓ 573ِٓ ّٙٓ اٌّلٜ . وٍفٓ 573اٌؾواهح ٕٚٚٛال ئٌٝ ٠جلأ ا١ٌٍٍَٛى ثبٌزؾًٍ ٚرى٠ٛٓ ِووجبد َِزم١ّخ ثَٕت وٍفٓ 673 أ٠جلوٍفٓ 673، ٚثلهعبد ؽواهح أػٍٝ ِٓ كٜ اٌَبثكالً ِٓ اٌُ ِزطب٠وح فف١فخ، اٌٍى١ٕٓ ثبٌزؾًٍ ثّؼلالد أػٍٝ ٚرى٠ٛٓ ِووجبد .َٚٔجخ ئٔزبط فؾُ افٚو الً ٠ّخ ثَٕت أػٍَِٝٚزك 0 10 20 30 40 50 60 70 80 90 100 500550600650700750800 درجة الحرارة، )كلفن( )% جم ح ( ة، وي مئ ال ة سب لن ا propane n-butane n-pentan i-pentan n-hexane nheptane انُست انًئىَخ نهًىاد انهُذروكبرثىَُخ تغُر ًَثم ( 3)انشكم رقى دقُقخ 15زيٍ انتفبعم )انُبتدخ يٍ انتفبعم ثًختهف درخبد انحرارح (. دقُقخ /نتر 0.1 انُتروخٍُ ويعذل خرَبٌ غبز وحدى تأثُر درخخ انحرارح عهً انًسبحخ انسطحُخ 3-1-3 انحُىٌنهفحى انًسبيبد ٠ً اٌؼاللخ ث١ٓ َٔجخ اٌَّبؽخ رُ رّش ،(4)فٟ اٌْىً هلُ رُ ؽَبة َٔجخ . ٚكهعخ ؽواهح اٌزؾًٍ اٌؾ١ٛٞاٌَطؾ١خ ٌٍفؾُ اٌَّبؽخ اٌَطؾ١خ فٟ وً كهعخ ئٌٝ اٌَّبؽخ اٌَطؾ١خ إٌبرغخ 0.34َ) وٍفٓ 773ثلهعخ ؽواهح اٌزؾًٍ ػٕل 2 ٔالؽع اْ . (غُ / ريكاك ثي٠بكح كهعخ ؽواهح اٌزؾًٍ، ٠ّٚىٓ ئ٠ؼبى٘ب ئٌٝ ٘نٖ إٌَجخ ,oh, aliphatic c-o–عاٌّغبِٟ ئىاٌخاٌي٠بكح اٌؼب١ٌخ ثّؼلالد ٚ ester c=o ٠ّٚىٓ . ِٓ اٌَطؼ اٌقبهعٟ ٌٍىزٍخ اٌؾ٠ٛ١خ ِٓ ِالؽظخ ٘نٖ اٌزغ١١واد ِٓ فالي ؽغُ اٌَّبِبد اٌّزىٛٔخ ٠ٓ َٔجخ ؽغُ ، ٚاٌنٞ ٠ّضً اٌؼاللخ ة(5)فالي اٌْىً هلُ رُ ِمبهٔخ . ِغ كهعخ اٌؾواهح اٌؾ١ٛٞاٌّزىْٛ ٌٍفؾُ اداٌَّبَ ؽغُ اٌَّبِبد اٌّزىٛٔخ فٟ وً كهعخ ؽواهح ِغ ؽغُ اٌَّبِبد ٔالؽع ثي٠بكح كهعخ .(وٍفٓ 773)اٌّزىٛٔخ ثلهعخ ؽواهح ؽغُ اٌَّبِبد، ٚ٘نا ثلٚهٖ ١ْ٠و ئٌٝ رى٠ٛٓ ىكاك َٔجخ داٌؾواهح ٘نٖ اْ . ٌٟ ى٠بكح اٌَّبؽبد اٌَطؾ١خٚثبٌزب َِبِبد أوضو كلخ اٌّالؽظبد رزفك ثْىً وج١و ِغ اٌىض١و ِٓ اٌّالؽظبد اٌّٛصمخ فٟ ;evita et al., 2013; steven et al., 2012)ثؾٛس ٍبثمخ joan et al., 2012; joeri et al., 2012; weiping et al., 2012; wei et al., 2010; mandu et al., 2010; sohi et al., 2010 .) ُ٠ج١ٓ ٔزبئظ اٌزؾب١ًٌ ٌٍَّبؽخ ( 2) اٌغلٚي هل اٌَطؾ١خ ٚؽغُ اٌَّبِبد ٌٍفؾُ اٌؾ١ٛٞ ثّقزٍف كهعبد . اٌؾواهح (2015) 92102، طفحخ 2، انعذد11دانخىارزيٍ انهُذسُخ انًدمجلة م قبسى حسٍُ عهىاٌ 97 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 500550600650700750800 درجت الحرارة، )كلفن( )( ت، حي ط س ال ت ح سا م ال ت سب ن ًَثم انعالقخ ثٍُ َسجخ انًسبحخ انسطحُخ ودرخخ ( 4)انشكم رقى دقُقخ ويعذل خرَبٌ غبز انُتروخٍُ 15زيٍ انتفبعم )حرارح انتحهم (. دقُقخ/نتر 0.1 ( 2)رقى خذول انًسبحخ انسطحُخ وحدى انًسبيبد نهفحى انحُىٌ ثًختهف درخبد . انحرارح المساحة السطحية م) 2 (غم/ حجم المسامات م) 3 (غم/ درجة الحرارة (كلفن) 0.335 0 523 0.647 0 573 2.78 0.0089 623 5.68 0.0178 673 13.66 0.02 773 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 500550600650700750800 درجت الحرارة، )كلفن( )( ت، م سا م ال م ج ح ت سب ن حدى انًسبيخ ودرخخ حرارح ًَثم انعالقخ ثٍُ َسجخ ( 5)انشكم رقى / نتر 0.1دقُقخ ويعذل خرَبٌ غبز انُتروخٍُ 15زيٍ انتفبعم )انتحهم (. دقُقخ تأثُر درخخ انحرارح عهً يحتىي انًبء نهفحى 3-1-4 انحُىٌ رُ رّض١ً اٌؼاللخ ث١ٓ َٔجخ ِؾزٜٛ اٌفؾُ اٌؾ١ٛٞ ِٓ اٌّبء ٔالؽع فٟ ٘نا اٌْىً(. 6)ٚكهعخ ؽواهح اٌزؾًٍ ثبٌْىً هلُ . ى٠بكح ِؾزٜٛ اٌفؾُ اٌؾ١ٛٞ ِٓ اٌّبء ِغ اىك٠بك كهعخ اٌؾواهح ٕٚ٘ب رغله اإلّبهح ئٌٝ اٌزأص١و اٌىج١و ٌلهعخ اٌؾواهح ػٍٝ لبث١ٍخ اٌفؾُ اٌؾ١ٛٞ ػٍٝ االِزٖبٓ ثَجت اٌي٠بكح اٌىج١وح فٟ اٌَّبؽخ اٌَطؾ١خ ٟٚ٘ اٌّإّو اٌوئ١َٟ ٌملهح اٌفؾُ اٌؾ١ٛٞ ػٍٝ اٌجؾش رزٛافك ِغ اٌىض١و ِٓ اٌّالؽظبد اْ إٌزبئظ . االِزٖبٓ ;evita et al., 2013)اٌزٟ أ١ّو ئ١ٌٙب فٟ كهاٍبد ػل٠لح steven et al., 2012; joan et al., 2012; joeri et al., 2012; weiping et al., 2012 .) ُ٠ج١ٓ ٔزبئظ ( 3)علٚي هل . رؾب١ًٌ اٌّؾزٜٛ اٌّبئٟ ٌٍفؾُ اٌؾ١ٛٞ ثّقزٍف كهعبد اٌؾواهح ( 3)ول رقى خذ . انًحتىي انًبئٍ نهفحى انحُىٌ ثًختهف درخبد انحرارح %(وزن)المحتوى المائي (كلفن)درجة الحرارة 4.90 523 6.28 573 6.48 623 4.28 673 7.91 773 0.4 0.5 0.6 0.7 0.8 0.9 1 500550600650700750800 درجت الحرارة، )كلفن( )( ء، ما ال ى و حت م بت س ن ًَثم انعالقخ ثٍُ َسجخ يحتىي انًبء نهفحى انحُىٌ ( 6)انشكم رقى قُقخ ويعذل خرَبٌ غبز د 15زيٍ انتفبعم )ودرخخ حرارح انتحهم كهفٍ 773دقُقخ ويحتىي انًبء ثذرخخ حرارح /نتر 0,1انُتروخٍُ %(. وزٌ 7,9= ftirتحبنُم -3-2 اْ رؾل٠ل ٔٛػ١خ اٌّغب١ِغ اٌفؼبٌخ ٌٍفؾُ اٌؾ١ٛٞ فب١ٕخ ِّٙخ اٌْىً هلُ . علاً، الْ ٚعل٘ب ٠ؾلك فؼب١ٌزٗ ٚثبٌزبٌٟ رؾلك وفبءرٗ ٌٍىزٍخ اٌؾ٠ٛ١خ ٌّٕٚبمط اٌفؾُ ٠ftirّضً أ١ٛبف رؾب١ًٌ ( 7) ٠ّىٓ اْ ٔالؽع ٚعٛك ؽيَ . اٌؾ١ٛٞ ثّقزٍف كهعبد اٌؾواهح ٚاٍؼخ ِٓ األٛٛاي اٌّٛع١خ ثبٌْىً اٌنٞ ٠قٍك ٕؼٛثخ فٟ ر١١ّي٘ب ٚثبٌزبٌٟ رؾل٠ل اٌّغب١ِغ اٌفؼبٌخ ٌٍىزٍخ اٌؾ٠ٛ١خ ٚاٌفؾُ ٚػٍٝ ٘نا األٍبً رُ اٌزؼ١ٍك ػٍٝ اٌّغب١ِغ اٌوئ١َ١خ . اٌؾ١ٛٞ . ْ رم١َّٙب ئٌٝ فٌّ ِل٠بد٠ّٚه ٍُ 4000ئٌٝ 3500األػلاك اٌّٛع١خ ّٙٓ اٌّلٜ (1) -1 ٚوّب ، ر١ْو اْ االِزلاكاد اٌّٛعٛكح (أ– 7)ِج١ٓ فٟ اٌْىً هلُ ، ٚاٌزٟ ث١ٓ ٚعٛك ِووجبد اٌف١ٕٛي اٚ o-hٟ٘ ِٓ ٔٛع ئٌٝ 250ٚػٕل ى٠بكح كهعخ اٌؾواهح ّٙٓ اٌّلٜ . اٌىؾٛالد 500َºف رمً ثّؼٕٝ آفو اْ َٔجخ ٘نٖ ، ٔالؽع اْ ّلح األ١ٛب اٌّووجبد فٟ اٌىزٍخ اٌؾ٠ٛ١خ رمً ٚونٌه ٌٛؽع افزفبء ثؼٚٙب -7ة ئٌٝ -7)ا٢فو، ٠ّٚىٓ رؼي٠ي ٘نٖ اٌظب٘وح ثبإلّىبي (. ٘ـ (2015) 92102، طفحخ 2، انعذد11دانخىارزيٍ انهُذسُخ انًدمجلة م قبسى حسٍُ عهىاٌ 98 ، 1-ٍُ 3500ئٌٝ 3000األػلاك اٌّٛع١خ ّٙٓ اٌّلٜ (2) ، c=oٚٔالؽع رىْٛ ثؼ٘ اٌّغب١ِغ اٌفؼبٌخ ِٓ االِزلاك c-h ٌٝٚعٛك األؽّبٗ اٌىبهثٛو١ٍ١َخ اٌزٟ ر١ْو ئ ٚاٌّووجبد االهِٚبر١خ، ٔالؽع اْ ٘نٖ اٌّٛاك غ١و ِٛعٛكح . فٟ اٌىزٍخ اٌؾ٠ٛ١خ ٠ٚجلا رى٠ٕٛٙب ثبهرفبع كهعخ اٌؾواهح ٍُ 3000ئٌٝ 2500 (3) -1 ٕ٘بٌه ئّبهح ؽبكح ٌؼلك ِٛعٟ ٠لي ، ٚاٌنٞ ١ْ٠و ئٌٝ ٚعٛك c-h ،c=oػٍٝ ٚعٛك االِزلاك و١ٕبد ٚاالٌل٠ٙب٠لاد، ٚٔالؽع اْ ِووجبد االٌىبٔبد ٚاالي َٔجزٙب رزغ١و ٚٔٛػ١زٙب أ٠ٚب ثبهرفبع كهعبد اٌؾواهح ٚوّب (. ٘ـ-7أ ئٌٝ -7)٘ٛ ِج١ٓ فٟ األّىبي ر١ْو 1-ٍُ 2500ئٌٝ 2000األػلاك اٌّٛع١خ ّٙٓ اٌّلٜ (4) ، ٚ c≡cئٌٝ االِزلاكاد اٌقبٕخ ثبٌّغب١ِغ اٌفؼبٌخ ِٓ ٔٛع c-h ٌى١ٕبد اٌزٟ رلي ػٍٝ ٚعٛك ِووجبد اال ٚاالٌل٠ٙب٠لاد، ثبإلٙبفخ ئٌٝ ِووجبد ٔزوٚع١ٕ١خ (nitriles .) ام ٔالؽع اْ رىٛٔٙب ٠يكاك ثي٠بكح كهعخ اٌؾواهح (. ٘ـ-7أ ئٌٝ -7)ٚؽَت ِب ِج١ٓ فٟ األّىبي 2500ئٌٝ 1500ٚأف١وا األػلاك اٌّٛع١خ ّٙٓ اٌّلٜ (5) ، c=o ،c-h ٚc-c، رلي ػٍٝ ٚعٛك االِزلاكاد 1-ٍُ ٚعٛك ِووجبد االٌى١ٕبد ٚاٌى١زٛٔبد ؽ١ش رلي ػٍٝ ٚاٌّووجبد االهِٚبر١خ ، رى٠ّٛٓ ٘نٖ اٌّووجبد ٠فًٚ كهعبد اٌؾواهح اٌم١ٍٍخ ٠ّٚىٓ ِالؽظزٙب ثْىً ٚاٙؼ فٟ األّىبي (. ٘ـ-7أ ئٌٝ -7) .طُف انكتهخ انحُىَخ( أ) . كهفٍ 523طُف انفحى انحُىٌ انًُتح ثذرخخ حرارح ( ة) . كهفٍ 623و انحُىٌ انًُتح ثذرخخ حرارح طُف انفح( خـ) (2015) 92102، طفحخ 2، انعذد11دانخىارزيٍ انهُذسُخ انًدمجلة م قبسى حسٍُ عهىاٌ 99 . كهفٍ 673طُف انفحى انحُىٌ انًُتح ثذرخخ حرارح ( د) . و773ºطُف انفحى انحُىٌ انًُتح ثذرخخ حرارح ( هـ) 0.1اٌ غبز انُُتروخٍُ دقُقخ ويعذل خرٌ 15وزيٍ االستجقبء )أطُبف انكتهخ انحُىَخ وانفحى انحُىٌ انًُتح ثذرخبد حرارح يختهفخ ( 7)انشكم رقى (. دقُقخ/نتر االستُتبخبد .4 اْ اٌجؾش اٌؾبٌٟ ٠ووي ثْىً فبٓ ػٍٝ ئٔزبط اٌفؾُ اٌؾ١ٛٞ اْ اٌٙلف . ثؼ١ٍّخ اٌزؾًٍ اٌؾواهٞ ٌَؼف إٌق١ً وىزٍخ ؽ٠ٛ١خ األٍبٍٟ ِٓ اٌجؾش ٘ٛ هثٜ ئٔزبط اٌفؾُ ٚفٖبئٖٗ ثظوٚف ِؼلي أزبط ث١ٕذ إٌزبئظ اْ َٔجخ. ئٔزبعٗ ٚثبٌىزٍخ اٌؾ٠ٛ١خ ٚفٖبئٔ ٚثٕبءاً . اٌفؾُ اٌؾ٠ٛ١خ رزأصو ثْىً وج١و ثظوٚف اٌزؾًٍ اٌؾواهٞ فٟ اٌفمواد اٌَبثمخ ِٓ اٌجؾش ٠ّىٓ اٌقوٚط ٖػٍٝ ِب رُ ػوٗ : ثبالٍزٕزبعبد ا٢ر١خ اْ َٔجخ ِؼلي ئٔزبط اٌفؾُ اٌؾ١ٛٞ رمً ثْىً ٍِؾٛظ ثي٠بكح كهعخ . وٍفٓ 773ئٌٝ 523اٌؾواهح، ّٙٓ اٌّلٜ ٔٛارظ اٌزؾًٍ اٌؾواهٞ ٌٍىزٍخ اٌؾ٠ٛ١خ رؼزّل ثٖٛهح اْ .1 ِجبّوح ػٍٝ كهعخ اٌؾواهح ٚػٍٝ روو١جخ اٌىزٍخ اٌؾ٠ٛ١خ ِٓ (. ا١ٍَّ١ٌٍٙٛى، ا١ٌٍٍَٛى ٚاٌٍى١ٕٓ)اٌّىٛٔبد اٌوئ١َ١خ ، ثي٠بكح كهعخ اٌؾواهح ريكاك اٌَّبؽخ اٌَطؾ١خ ٌٍفؾُ اٌؾ١ٛٞ .2 .ٚونٌه َٔجخ ؽغُ اٌَّبِبد ؽ١ٛٞ الِزٖبٓ اٌّبء ريكاك ثي٠بكح كهعخ اْ لبث١ٍخ اٌفؾُ اي .3 .ؽواهح اٌزؾًٍ اٌؾواهٞ ٕٚف ِّزبى ٌٍزغ١واد اٌزٟ رؾلس ftirأػطذ رؾب١ًٌ .4 ثبفزالف كهعخ اٌؾواهح ٔالؽع . ٌٍىزٍخ اٌؾ٠ٛ١خ ٚاٌفؾُ اٌؾ١ٛٞ ا١ٍَّ١ٌٍٙٛى، ا١ٌٍٍَٛى )رأص١و رؾٛي اؽل اٌّىٛٔبد األٍب١ٍخ ٠خ ٚٔٛارظ فؾُ اٌؾ١ٌٛىزٍخ اٌؾ٠ٛ١خ ػٍٝ روو١جخ ايا( ٚاٌٍى١ٕٓ اٌّغب١ِغ اٌفؼبٌخ اٌزٟ رؾلك فؼب١ٌخ ونٌه اٌزؾًٍ اٌؾواهٞ ٚ .اٌفؾُ اٌؾ١ٛٞ انًظبدر .5 [1] amir mehdi dehkhoda, alex h. west, naoko ellis, (2010), ―biochar based solid acid catalyst for biodiesel production‖, applied catalysis a: general, 382, pp. 197– 204. 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[37] zhengang liu, augustine quek, s. kent hoekman, r. balasubramanian, (2013), ―production of solid biochar fuel from waste biomass by hydrothermal carbonization‖, fuel, 103, p.p. 943–949. qasim h. alwan al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 2030 (2015) 102 characterization of biochar produced from iraqi palm fronds by thermal pyrolysis qasim h. alwan* ameel mohammed rahman** mohanned hassib salman** zainab hassan ali* abdul karim abdul satar* anwar shaker* janan abdul ameer* * center of chemical and petrochemical research/ board of research and development/ ministry of industry ** department of biochemical engineering/ al-khwarizmi college of engineering/ university of baghdad *email: dursaf1968@yahoo.com ** email:explorerxp50@yahoo.com abstract the present paper focuses in a particular on the study of the biochar production conditions by the thermal pyrolysis of biomass from local iraqi palm fronds, in the absence of oxygen. the biochar product can be used as soil improvers. the effect of temperature on the extent of the thermal pyrolysis process was studied in the range from 523 to 773k with a residence time of 15 minutes and nitrogen gas flow rate of 0.1 l/min. the produced biochar was characterized as will as biomass and degradation products. the results showed that the rate of biochar production decreases with the increasing in temperature, also it was noted that the normalized biochar surface area and pore size increases with the increasing in temperature. the results showed an increase in the biochar ability to absorb water and the percent of water content increases with increasing temperature. the quality and quantity of the products of the thermal pyrolysis of biomass depend directly on the temperature and on the biomass basic composition of the compounds: hemicellulose, cellulose and lignin. ftir analysis gave an excellent description to the nature of the active groups on the biochar surface. these groups vary with the temperature and biochar composition (i.e. hemicellulose, cellulose and lignin). mailto:dursaf1968@yahoo.com mailto:**explorerxp50@yahoo.com <4d6963726f736f667420576f7264202d2038332d393020e3decfc7e320d8c7d1de20e6dac7c6cfc920e6d1d4c7> al-khwarizmi engineering journal al-khwarizmi engineering journal,vol. 13, no. 3, p.p. 8390 (2017) thermal conductivity enhancement of iraqi origin paraffin wax by nano-alumina miqdam t. chaichan* rasha mohammed hussein** aida mohammed jawad*** *energy and renewable energies/ university of technology **department of mechanical engineering/university of technology ***the middle technical university *email: 20185@uotechnology.edu.iq **email: mechanicalflower99@yahoo.com ***email: aida200899@yahoo.com (received 7 november 2016; accepted 22 february 2017) https://doi.org/10.22153/kej.2017.02.003 abstract paraffin wax is utilized for the heat storage applications taking advantage from the high stored latent heat during the phase change (from solid to fluid) period. what isn't right with this procedure is that the wax has a little heat transfer rate because of its low thermal conductivity. the thermal conductivity improvement of the paraffin wax has been examined utilizing nano-material with high thermal conductivity. in the recent study, (al2o3) nanoparticles with weights of 1, 2, and 3% of the paraffin wax were added to the paraffin wax. the iraqi paraffin wax accessible at the local markets was utilized as a phase change material (pcm). many properties of the wax were changed due to the addition of nanofillers. the wax color was changed from light brown to white. the thermal conductivity of the paraffin wax was expanded by increasing the additional nanoparticles extent with 37.1, 42.3 and 60.32% for 1, 2 and 3% added nano-al2o3 compared to pure wax conditions. the subsequent change in the thermal conductivity of the paraffin wax makes it reasonable for the use in thermal storage applications. keywords: latent heat, nano-alumina, paraffin wax, thermal storage, 1. introduction the world's vitality circumstance came to an intersection, and the subject of whether there is a different option to the small oil assets or not [1]. the ascent in oil costs demonstrates the recorded decay of oil assets. the renewable energy sources, for example, nuclear power, solar energy, wind energy, and other renewable energies, as hydrogen fuel cells can get to be feasible contrasting options to fossil fills later on. many valuable studies upheld the assessment that the end of the oil time is coming following a couple of decades [2]. with the unpredictability of the issue, the affirmation of this suspicion is far with the advancement of innovations used to produce oil and gas in various parts of the world [3]. to exploit solar energy is an impediment to specialists, as the solar radiation oscillates with the time and the dilemma of using it around evening hours. in this way, enhancing the thermal storage will diminish the effect of sunlight oscillation. the improvement in the energy storage of any system will increase its effectiveness and expand the consistent quality, and it assumes a critical part in keeping up the delivered energy [4]. the phase change materials are utilized to store thermal energy in solar energy applications. variable phase change materials (pcm) have high latent heat storage capacities at the stage of phase miqdam t. chaichan al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 8390 (2017) 84 change period from a solid to a fluid state, or from the fluid to the solid state. during this process, this material can store around 5 to 14 times the energy per unit volume, contrasted to the sensible heat storage materials, such as water, stone masonry, or rock. its low thermal conductivity portrays paraffin wax as other pcms. this character limits the absorption and energy release rate. many researchers have utilized variable sorts of fillers with high thermal conductivity to enhance the effective thermal conductivity of the phase change material. fukai abused ceramic powder fillers and graphitic carbon fiber [5], pincemin utilized graphite particles [6], kim used peeled graphite as a part of his works [7], and elgafy employed carbon nanofibers [8]. current nanomaterials show physical and chemical properties contrast essentially when compared to the base mass structure [10]. the generation of various sorts of nanoparticles has ended up less demanding as a result of the fast advance in nanotechnology [11], mechanical and electronic building, and current procedures [12 and 13]. the higher thermal conductivity of the nanomaterials created from metals or metal oxides can be utilized with low conductivity materials as pcms to improve its thermal conductivity [14]. a higher thermal conductivity can be accomplished at smaller nanomaterials size. the enhanced of thermal conductivity of pcms causes advancements in its thermal qualities [15]. wang figured out how to include nanomaterials for paraffin wax without bringing about any surface strain. the outcomes demonstrated that the expansion of nano-tio2 in paraffin wax bringing on an adjustment in the thermal limit of the phase change material. the thermal conductivity of the wax additionally expanded plainly [16]. fan researched the impact of including different extents of carbon nanofillers on the courier and energy storage and thermal properties of materials utilizing paraffin (pcms). the thermal capacity of the formed material was slightly less with the nano-fillers addition; however, it has no impact on the temperature of the phase change. the outcomes demonstrated that the thermal conductivity of the pcms nanocomposite increments with the expansion of the extent of fillers. likewise, the relative change in the thermal conductivity relies upon the size and state of the added nanoparticles material [17]. chaichan added two types of nano materials to the paraffin wax in variable mass fractions. al2o3 and tio2 were used to improve the thermal conductivity of the used pcm. the results indicated that thermal conductivity was improved with increasing the nanofillers mass fraction. the results revealed significant enhancement in the wax's charging and discharging period which was reduced with the addition of nanofillers [18]. the use of nano materials-paraffin wax composite gets wider interest in different applications, especially those related to the uses of solar thermal applications [19 & 22]. the present study demonstrates the test examination of the performance enhancement due to the expansion of al2o3 nanoparticles in the paraffin wax in various weights. the essential objective of this study is to assess the best proportion of nanoparticles that can be added to iraqi paraffin wax to improve its thermal conductivity. 2. experimental setup 2.1. experimental procedure the iraqi paraffin wax was picked as pcm in the present study. it was selected due to its nominal melting point around 45ºc. table 1 gives the details of the thermal and physical properties of the utilized wax. nano-alumina with grain size from 30 to 60 nm was used in this work. table 2 demonstrates the details of the suppliers and properties of this material. these materials were chosen as a result of its accessibility and low costs; and were utilized with no additional purification procedures as got from the supplier. the technique for blending the wax with nanoparticles can be partitioned into five phases: 1. pre-dissolving of unadulterated pcms (as they received by the provider), it was melted to perform the homogeneous immaculate material. the fluid paraffin has been filled in vials to facilitate the handling in the next stages. the material has been chilled off at room temperature; the paraffin wax was premelted and degassed in a vacuum stove at 105ºc for 3 hours. 2. the nano-material and the paraffin wax were weighed to prepare the correct samples. the nano-fillers samples with mass fractions of 1, 2 and 3% wt. were prepared. 3. the nano-material was dried at the same condition of the wax in the oven. 4. the samples of nano-al2o3pcm prepared using a melting mixing procedure. at first, the nanomaterial added to the molten wax with required percentage, and strong shear mixing with a magnetic stirrer for 15 min was used to miqdam t. chaichan al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 8390 (2017) 85 mix the nano-al2o3 totally. this process was followed by an intense shaking using an ultrasonic shaker for five hours. the used ultrasonic shaker used type alabtech (exxx_1000), which picture is illustrated in fig. 1. the process was conducted by putting the required nanoalumina fraction with the wax in a closed vessel immersed in 65°c hot water. each sonication run of the devise was set to be 99 minutes. the samples temperatures were maintained at 65 °c during the mixing process to confirm the liquid phase of the wax. fig. 1. ultrasonic shaker type albatech (exxx1000). after the complete mixing of wax and nanoal2o3, it was followed by the solidification process. the mixture was poured in a circular template with dimensions of 2 cm dia., and then was allowed to solidify freely at room temperature (25°c) to form a solid paraffin wax. this solidification process completed at about three hours. table 1, thermo-physical properties for the iraqi paraffin wax [18] material properties melting temperature (°c) 44 °c latent heat of fusion (kj/kg) 190 solid density (kg/m3) 930 liquid density (kg/m3) 830 thermal conductivity (w/m °c) 0.21 specific heat (solid) (kj/kg °c) 2.1 specific heat (liquid) (kj/kg °c) 2.1 table 2, the suppliers and the used nano-fillers specifications item al2o3 specifications manufacturer yurui chemical co., ltd appearance white powder assay 99.99% ph value 7.5 crystal and type a grain size nm 30-60 nm bulk density ％ 0.43 loss on drying ％≤ 0.21 sulfated assay ％≤ 0.42 fe ≤ ppm ≤0.005% si ≤ ppm ≤0.003% mg ≤ ppm ≤0.001% 2.2. experimental instruments the following instruments were used in the tests: 1. the scanning electron microscopy (sem) was used to display the surface micrographs of representative wax-nano al2o3 samples. fig 2 shows the main parts of the sem that is the electron column, detectors, scanning system, and vacuum system, display, and electronics controls. the electron microscopy can generate the electron beam on the surface of the sample with a size spot up to 10 nm diameter, and holds the remains sufficient current to form an acceptable image. 2. hot disk thermal constants analyzer (fig. 3) was used to measure the thermal conductivity of the samples. this device has a sensor plane passing hot consists of an electrically conducting pattern etched into the chip of thin nickel. this spiral is located between two sheets of insulation mica material. when the thermal conductivity measurement is performed, the aircraft sensor hot disk is fixed between two pieces of the sample facing the sensor surface. by passing an electric current high enough to cause an increase in the sensors temperature, and is at the same time, recording the temperature increase with time. every test was repeated three times and the average was taken as the representative reading. the standard deviations of the data found to be less than 2% for the measurements. 2.3. test procedure the tests began by setting up the wax tests. the second step was to get quick examples of miqdam t. chaichan al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 8390 (2017) 86 nano-filler and wax suspensions. after the preparing the specimens, the thermal conductivity tests were begun utilizing hot disk thermal constants analyzer. both the softening and cooling practices were tried by warming the specimens in a compartment to 65ºc and the abandon it to cool by natural convection in the air which its temperature was kept up at 25ºc. the wax and wax-nano composite tests temperature were measured and recorded amid every period. the outcomes were analyzed and discussed. fig. 2. the scanning electron microscopy (sem). fig. 3. hot disk thermal constants analyzer. 3. results and discussion the mixing of nanoparticles with wax results in a change in the color of the wax as shown in fig. 4 (a and b). the color of the wax has turned from light brown (fig. 4 a) to faint white color (fig. 4 b). the proper mixing of the material with nanoparticles means the nano-al2o3 entered within the paraffin wax composition thus changing its characteristics. among these features is the wax color. the color of the wax changing gives a clear indication of good mixing between the nanoparticles and wax. the nano-wax composite's color was affected slightly by the nano-alumina fraction variation. fig. 4. (a) the paraffin wax before mixing with nano-al2o3 and (b) after the mixing fig. 5 represents the wax-nano al2o3 suspension surface nature as it seems by the sem scanning. the figure indicates that the nanoalumina-paraffin wax has non porous structure. it appears as one phase shape of the structure in (fig. 5a), and any difference may seem in figs. 5 b &c are due to the non-crystallite between wax and nano-al2o3. the figures reveal acceptable dispersion of the nanomaterial into the wax. this dispersion at 100nm scale was with few nano al2o3 agglomerations, but it has a strong interaction between wax and the nanoparticles. the distributions at 50nm scale (fig. 5 b) and 20nm range (fig.5 c) manifest strong interaction between both materials. miqdam t. chaichan al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 8390 (2017) 87 the temperature impact on the thermal conductivity of the paraffin wax and its nanoal2o3 composites is outlined in fig. 6. adding nano-alumina to the wax increased its thermal conductivity as the figure reveals. the phenomenon of higher thermal conductivity of the nano-al2o3-pcm composite than the case of wax alone resulted from lower thermal resistance. also, the figure clearly shows that the thermal conductivity of the tested materials is temperature dependent, as its thermal conductivity decreased with increasing temperature. the paraffin thermal conductivity achieved its insignificant at the melting point, and after this stage, it came back to rise. the paraffin wax thermal conductivity was influenced by the expansion of nano-al2o3. the nano-al2o3 expansion enhanced the heat exchange rates by 37.1, 42.3 and 60.32% for 1, 2 and 3% added nano-al2o3. the liquefying change period from solid to fluid brought on a decrease in the thermal conductivity through this time. table 3 illustrates the experimental results. table 3, the experimental results. temperature (°c) thermal conductivity paraffin wax pw+1% nano al2o3 pw+2% nano al2o3 pw+3% nano al2o3 25 0.08894 0.09382 0.099101 0.1073 35 0.05817 0.076043 0.079022 0.091001 45 0.037898 0.06109 0.0635 0.07102 55 0.044367 0.0712 0.07327 0.087107 65 0.047897 0.0782 0.079902 0.088108 fig. 7 demonstrates that the nanoparticles enhanced the thermal conductivity of the paraffin wax yet this upgrade was changing with the additional nano-al2o3 fraction. gharagozloo [23] presented a relation of the relative thermal conductivity improvement by the condition: relative improvement = (k – ko)/ko this relation quantitatively connects the capability of thermal conductivity increment with the nanomaterial quantity. nano-al2o3-wax suspension accomplished an extensive change. it is hard to compare between various literatures findings because of the usage of variable paraffin wax types and nano-particle sizes. fig. 7 shows a comparison between the present results and the data reported in the literature. enhancement in the thermal conductivity is evident whatever the type of the wax depending on the nano-al2o3 quantity added with the addition of other parameters as the nanomaterial size, shape, and distribution figure. arusu [24] improved the paraffin wax by adding nanoalumina particles and compared the variation in thermal conductivity with pure paraffin wax. fig. 6. thermal conductivity during the temperature variation for the wax and nano-al2o3wax composites. fig. 5. scanning emission microscopic test (sem) of the paraffin wax-nano al2o3 suspension miqdam t. chaichan al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 8390 (2017) 88 fig. 7. relative enhancement in thermal conductivity due to the added nano-fillers. the relative enhancement in the thermal conductivity in arusu case was lower than that of the recent study. this variation can be returned to the used paraffin wax difference. arusu used a wax with 321°c melting point while the recent study used 45°c melting point wax. table 4 lists the thermal conductivity relative enhancements for the arusu and recent study. table 4, the thermal conductivity enhancement variation for recent study and ref. 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[24] arasu v, mujumdar a s, numerical study on melting of paraffin wax with al2o3 in a square enclosure, international communications in heat and mass transfer, vol. 39, pp. 8-16, 2013. )2017( 83-90، صفحة 3دد، الع13دجلة الخوارزمي الهندسية المجلم مقدام طارق جيجان 90 تحسين الموصلية الحرارية لشمع البرافيين العراقي المنشأ باضافة األلومينا النانوية المنشأ ***عائدة محمد جواد **رشا محمد حسين *م طارق جيجانمقدا الجامعة التكنولوجية/ مركزتكنولوجيا الطاقة والطاقات المتجددة* الجامعة التكنولوجية /قسم الهندسة الميكانيكية** بغداد -جامعة الوسط التقنية /***الكلية التقنية uotechnology.edu.iq@20185*البريد االلكتروني: mechanicalflower99@yahoo.com**البريد االلكتروني: aida200899@yahoo.com***البريد االلكتروني: الخالصة فادة من الحرارة الكامنه لة خالل مرحلة تغير الطور (من صلب الى مائع). من زنة للحرارة ذات طاقة كامنه باأليستخدم الشمع البارافييني مادة خا راسة تحسين الموصلية الحرارية مساوئ هذة المادة معدالت انتقال حرارة قليله عند عمليات اإلنصهار/التجمد بسبب انخفاض الموصلية الحرارية لها. تمت د ، ٢، ١) النانوية بنسب وزنية من3o2alللشمع البارافييني باستخدام مادة نانوية ذات توصيل حراري مرتفع. إذ تمت في هذة الدراسة اضافة مادة األلمنيا ( ). pcmمادة متغيرة الطور ( بوصفه حليهالى الشمع البرافينيي عراقي االنتاج. تم استخدام شمع برافييني عراقي متوفر باألسواق الم %٣ البرافييني لوحظ تغير عدة خواص للشمع بسبب اضافة المادة النانوية. إذ تغير لون الشمع من اللون البني الى األبيض. أن الموصلية الحرارية للشمع النانوية الى الشمع بنسب ارتفعت بزيادة نسبة المادة النانوية الوزنية. كما تحسنت معدالت الشحن وتفريغ الشحن للطاقة الحرارية بشكل واضح باضافة المادة مقارنة بحالة استخدام شمع بمفرده. إن هذا التحسن في الموصلية الحرارية %٣، و٢، ١عند اضافة نانو المونيا بنسب وزنية %٦٠٫٣٢، و٤٢٫٣، ٣٧٫١ الستخدام في تطبيقات الخزن الحراري للطاقة.اللشمع البرافييني يمنح هذة المادة افضلية 15-25 al-khwarizmi engineering journal,vol. 12, no. 1, p.p. experimental study of the performance of compound concentrating qussai jihad abdul *,** department of mechanical engineering / ** (received abstract the design, construction and investigation of e with tubular absorber have been presented. the performance of cpcs have been evaluated by using outdoor experimental measurements including the instantaneous thermal efficiency. holding them on a common structure. many different levels. for each truncation the acceptance half angle ( angle for standard cpc is (26o). for the truncation levels for 20o, 26o and 59o, consequently. a significant difference between the instantaneous thermal efficiency of 3.86× cpc (θc=20o) and 2.32× cpc (θc=26o), and between that for 3.61× cpc ( the difference between the instantaneous thermal efficiency of 2.32× cpc ( compared with the difference of the first and second cases, the instantaneous thermal efficiency of 2.32× cpc (2 higher than those for other three cpcs. the experimental results show 2.32×cpc (26o) is 0.708, the maximum thermal efficiency of the 3.93×cpc (15 (20o), 3.61× cpc (26o) and 2.32× cpc (59 from (3.93× to 1×), the thermal efficiency, k.m2/w) and (0.494 to 0.797), respectively. keywords: cpc collector, truncation effect 1. introduction compound parabolic concentrator consists of two different parabolic reflectors that can reflect both direct and a fraction of the diffuse incident at the entrance aperture onto the absorber in addition to the direct solar radiation directly by the absorber [1]. cpc accept incoming solar radiation over a relatively wide range of incidence angles. by using internal reflections of ray, any radiation entering the collector's aperture within the cpc angle finds its way to the absorber surface located at the bottom of the collector [2]. since the invention of the compound parabolic concentrator (cpc), many researchers published that deal with a wide range of designs and analysis of this system. however, a close khwarizmi engineering journal,vol. 12, no. 1, p.p. 1525 (2016) experimental study of the performance of compound concentrating solar collector qussai jihad abdul-ghafour* mohammed aziz hassan department of mechanical engineering / university of technology * email: kaisyqj@yahoo.com ** email: mohammedeng37@gmail.com (received 26 april 2015; accepted 4 august 2015) the design, construction and investigation of experimental study of two compound parabolic concentrators with tubular absorber have been presented. the performance of cpcs have been evaluated by using outdoor experimental measurements including the instantaneous thermal efficiency. the two cpcs are tested instantly by holding them on a common structure. many tests are conducted in the present work by truncating one of them in three different levels. for each truncation the acceptance half angle (θc) was changed. geometrically, the acceptance half ). for the truncation levels for the other cpc 1, 2 and 3 the acceptance half angle were a significant difference between the instantaneous thermal efficiency of 3.86× cpc ), and between that for 3.61× cpc (θc=26o) and 2.32× cpc ( the difference between the instantaneous thermal efficiency of 2.32× cpc (θc=59o) and 2.32× cpc ( compared with the difference of the first and second cases, the instantaneous thermal efficiency of 2.32× cpc (2 higher than those for other three cpcs. the experimental results show that the maximum thermal efficiency of the full ) is 0.708, the maximum thermal efficiency of the 3.93×cpc (15o), when it's truncated to 3.84× cpc ) and 2.32× cpc (59o) are 0.51, 0.52 and 0.66, respectively. as the concentration ratio decreases from (3.93× to 1×), the thermal efficiency, energy losses and optical efficiency increase from (0.47 to 63), (1.58 to 7.2 espectively. truncation effect, thermal performance. compound parabolic concentrator consists of two different parabolic reflectors that can reflect both direct and a fraction of the diffuse radiation incident at the entrance aperture onto the absorber in addition to the direct solar radiation absorbed collectors can radiation over a relatively angles. by using multiple , any radiation entering cpc acceptance angle finds its way to the absorber surface located since the invention of the compound parabolic researchers have been published that deal with a wide range of designs system. however, a close examination of these researches great majority of them are devoted to the geometrical, optical and thermal analysis of the cpc with a tubular receiver. mcintire, 1979 [3], studied the truncation of non-imaging cusp reflectors which concentrate sunlight onto cylindrical shapes of reflector for truncated having various acceptance angles. concluded that the truncation leads to collector designs which are more cost e substantial reductions in mirror height and length with small reductions in concentration ratios. gordon, et al., 1985 expressions for the angular acceptance function of two-dimensional cpcs of arbitrary truncation degree. took into account the effect of truncation on both optical and thermal losses in real al-khwarizmi engineering journal (2016) experimental study of the performance of compound parabolic mohammed aziz hassan** university of technology study of two compound parabolic concentrators (cpcs) with tubular absorber have been presented. the performance of cpcs have been evaluated by using outdoor the two cpcs are tested instantly by truncating one of them in three ) was changed. geometrically, the acceptance half the other cpc 1, 2 and 3 the acceptance half angle were a significant difference between the instantaneous thermal efficiency of 3.86× cpc c (θc=26o). it's noticed that ) and 2.32× cpc (θc=26o) is small compared with the difference of the first and second cases, the instantaneous thermal efficiency of 2.32× cpc (26o) was that the maximum thermal efficiency of the full ), when it's truncated to 3.84× cpc ) are 0.51, 0.52 and 0.66, respectively. as the concentration ratio decreases losses and optical efficiency increase from (0.47 to 63), (1.58 to 7.2 researches reveals that the great majority of them are devoted to the and thermal analysis of the cpc with a tubular receiver. studied the truncation of p reflectors which concentrate sunlight onto cylindrical absorbers. presented the reflector for truncated cpc concentrators having various acceptance angles. finally, concluded that the truncation leads to collector designs which are more cost effective through substantial reductions in mirror height and length with small reductions in concentration ratios. [4], derived analytic expressions for the angular acceptance function of dimensional cpcs of arbitrary truncation . took into account the effect of truncation on both optical and thermal losses in real qussai jihad abdul-ghafour collectors, also evaluated the monthly and yearly collectible energy increasing. c yearly collectible energy increased and average number of reflection reduced with truncation. suzuki and kobayashi 1995 [5] optimum acceptance angle of a cpc by the use of an insolation model. the yearly insolation model suggested that the optimum half-acceptance angle at the two-dimensional cpc becomes 26° irrespective of the change of the diffuse radiation fraction. concluded that, a common cpc could be used as an optimum concentration, the world. winston and o'gallagher studied the performance of the non collectors cpc with tubular absorber (evacuated and selective surface), empirically in two groups with different concentrating ratio, the first low (1.1×-1.4×) and the other high (about 5×). they found that the first group don't needed diurnal tracking and its efficiency 40% at 150 second needed monthly tilt adjustment and its efficiency 60% at 220oc. tang, et al., 2010 developed a mathematical procedure to estimate the annual collectible radiation captured by fixed cpc oriented in east-west direction based monthly horizontal radiation. results showed that the optimal acceptance half-angle for maximizing cpc's annual energy collection was 25.97 yearly optimal tilt-angle of apertures relative to the horizon was equal to the site latitude. the aim of the present work is to evaluate the performance of the full cpc collector with different truncation levels and comparing the results with standard cpc collector with (26 acceptance half angle. 2. description of the cpc two models of cpcs have been manufactured and tested at a totally sunny space. these models consisted of a support structure that allows to position the cpcs at different angles, reflector parts assembly and evacuated tube absorbers as shown in fig. 1. the evacuated tube is used in this work as the absorber part. it consist of a double glass concentric tubes and the space between them is evacuated in order to reduce the convection losses. the inner tube is treated by a selective coating with specifications tabulated in table 1. fig. 2. show a schematic diagram of the evacuated tube [8]. geometrical characteristics the designed cpc collector, are given in table the previous researchers used number of cpcs models, symmetric and axisymmetric, with without transparent cover on the aperture, north al-khwarizmi engineering journal, vol. 12, no. 16 monthly and yearly concluded that yearly collectible energy increased and average reduced with truncation. [5], studied the optimum acceptance angle of a cpc by the use of an insolation model. the yearly insolation model acceptance angle dimensional cpc becomes 26° respective of the change of the diffuse radiation a common cpc could be used as an optimum concentration, almost all over and o'gallagher 2004 [6], studied the performance of the non-imaging solar with tubular absorber (evacuated and selective surface), empirically in two groups with different concentrating ratio, the first low 1.4×) and the other high (about 5×). they found that the first group don't needed diurnal y 40% at 150oc. the second needed monthly tilt adjustment and its c. tang, et al., 2010 [7], developed a mathematical procedure to estimate the annual collectible radiation captured by fixed west direction based on the monthly horizontal radiation. results showed that angle for maximizing cpc's annual energy collection was 25.97o, and the angle of apertures relative to the horizon was equal to the site latitude. aim of the present work is to evaluate the performance of the full cpc collector with different truncation levels and comparing the results with standard cpc collector with (26o) two models of cpcs have been adopted, manufactured and tested at a totally sunny space. these models consisted of a support structure that allows to position the cpcs at different angles, reflector parts assembly and evacuated tube the evacuated tube is used in this work as the absorber part. it consist of a double glass concentric tubes and the space between them is evacuated in order to reduce the convection losses. the inner tube is treated by a ons tabulated in table 1. fig. 2. show a schematic diagram of the eometrical characteristics of , are given in table 2. the previous researchers used number of cpcs models, symmetric and axisymmetric, with and without transparent cover on the aperture, northsouth and east-west axis oriented as shown in fig. 3. in this present work t symmetric, without transparent cover plate and oriented e-w, south facing. fig. 1. the schematic of cpc colle table 1, evacuated tube specifications parameters units receiver length mm cover diameter mm absorber diameter mm cover transmittance % coated surface absorptance % coated surface emittance % pressure of vacuum space pa heat loss w/m insolation temp. � fig. 2. schematic diagram of the evacuated , no. 1, p.p. 1525 (2016) west axis oriented as shown in fig. 3. in this present work the cpcs used are transparent cover plate and w, south facing. fig. 1. the schematic of cpc collectors. evacuated tube specifications [8]. units values mm 1800 mm 58 mm 47 % 91 % 93 % <8 pa 5×10-3 w/m2� < 0.8 � 250 fig. 2. schematic diagram of the evacuated tube. qussai jihad abdul-ghafour al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 1525 (2016) 17 table 2, the geometrical characteristics of the designed cpc collectors. cpc's support structure consists of two group assemblies: stationary base assembly, in order to undergo the hard weather conditions, and achieve fig. 3. schematic diagram of the cpc with transparent cover and symmetric axis. the supporting requirement through the solar energy collectors operation. and the other, tilting part assembly where the cpcs supported on, it allows to position the cpcs at different tilt angles. the reflector is designed to set the acceptance half angle 15o and truncated in three levels, to 20o (3.84× cpc), 26o (3.61× cpc) and 59o (2.32× cpc) as illustrated in fig. 4. a second reflector is designed to set acceptance half angle 26o (2.32× cpc) as illustrated in fig. 5. cartesian coordinate system and the optical axis of the concentrator as the y-axis, the two sections: involution and reflection sections of the reflector curves are drawn separately to achieve the ideal concentration ratio as shown in fig. 6. any point on the reflector is [9]: � = � sin� − (�)cos� …(1) � = −� cos� − (�) sin � …(2) where : (�) for θm ≤ |θ| ≤ θc + π/2 : (�) = �� + ��� sin�� + �(� + ��) …(3) for θc + π/2 ≤ θ ≤ 3π/4 – θc : (�) = �(��� � � �������� !"���#$%(����)) &�%'"(����) …(4) x axis (mm) -400 -300 -200 -100 0 100 200 300 400 y a xi s ( m m ) -200 0 200 400 600 800 1000 1200 1400 3.84x cpc reflector 3.61x cpc reflector 2.32x cpc reflector 2.32x cpc aperture 3.61x cpc aperture 3.84x cpc aperture focus point 3.93x cpc reflecotr 3.93x cpc aperture ig no re d in th e ex pe ri m en ta l t es ts ig no re d in th e ex pe ri m en ta l t es ts 3. 84 x c p c 3. 61 x c p c 2. 32 x c p c fig. 4. illustration of designed 3.84× cpc. parameters units 2.32× cpc 3.84× cpc acceptance half-angle deg. 26 15 truncation deg. full cpc 20 26 59 geometric concentrati on ratio -2.32 3.84 3.61 2.32 aperture area m2 0.512 0.848 0.797 0.51 2 aperture width m 0.343 0.567 0.533 0.34 3 length of the cpc m 1.495 1.495 qussai jihad abdul-ghafour x axis (mm) -200 -150 -100 -50 0 50 y ax is ( m m ) -100 0 100 200 300 400 500 2.32x cpc reflector focus point fig. 5. illustration of designed 2.32× cpc. fig. 6. two sections of cpc: (a) involution (b) reflection [9]. 3. experimental setup and performance indexes 3.1. experimental setup the experimental unit has the following elements as shown in fig. 7. : (1)2.32× cpc, (2) 3.84× cpc,(3) two 48 liter storage tanks, one for each cpc, and (4) two circulating pumps, with al-khwarizmi engineering journal, vol. 12, no. 18 100 150 200 . illustration of designed 2.32× cpc. . two sections of cpc: (a) involution (b) experimental setup and performance the experimental unit has the following 2.32× cpc, (2) 3.84× cpc,(3) two 48 liter storage tanks, one for each cpc, and (4) two circulating pumps, with mass flow rate of 0.02 kg/s, the circulation pump had two functions, which were (i) homogeniz the water temperature in the storage tank breaking up the stratification of the circulating the water through the cpc tube at constant mass flow rate. a flexible tubes are used for conveyance of the investigate the thermal performance of cpcs, the water temperatures at inlet and outlet of the absorber tubes, the temperature of the tank, and solar radiation intensity (beam and diffuse) are measured during the experiments. 3.2. performance indexes the optical performance of cpc collectors can be analyzed theoretically, by obtaining values of the optical efficiency and incidence angle modifier (iam) with respect to incidence angle projections, by using ray tracing evaluate thermal performance of the 2.32×cpc and 3.84× cpc collectors, thermal efficiency must be considered. the data for the beam and diffuse solar radiations and useful heat gain by the cpcs were obtained previously to determine the instantaneous and daily efficiencies 3.2.1. optical efficiency optical efficiency obtained by using three dimensional ray tracing program trace pro [10]. to simulate solar radiation above the plane of the collector, 1000 rays are randomly distributed over the width of the aperture. the fraction of impacted rays on the absorber gives an optical efficiency value for an incidence angle. , no. 1, p.p. 1525 (2016) mass flow rate of 0.02 kg/s, the circulation pump had two functions, which were (i) homogenization the water temperature in the storage tank by reaking up the stratification of the water, and (ii) through the cpc absorber constant mass flow rate. a flexible tubes are used for conveyance of the water. to investigate the thermal performance of cpcs, the es at inlet and outlet of the temperature of the storage tank, and solar radiation intensity (beam and diffuse) are measured during the experiments. indexes the optical performance of cpc collectors can be analyzed theoretically, by obtaining values of the optical efficiency and incidence angle modifier (iam) with respect to incidence angle projections, by using ray tracing software. and to rformance of the 2.32×cpc and 3.84× cpc collectors, thermal efficiency must be considered. the data for the beam and diffuse solar radiations and useful heat gain by the cpcs were obtained previously to determine the instantaneous and daily efficiencies ηth. optical efficiency optical efficiency obtained by using three dimensional ray tracing program trace pro [10]. to simulate solar radiation above the plane of the collector, 1000 rays are randomly distributed over the width of the aperture. the fraction of impacted rays on the absorber gives an optical efficiency value for an incidence angle. qussai jihad abdul-ghafour al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 1525 (2016) 19 fig. 7. a photograph of cpcs setup. 3.2.2. thermal efficiency the cpc instantaneous thermal efficiency of the cpcs for three cases (i) 3.86× cpc (θc=20o) and 2.32× cpc (θc=26o), (ii) 3.61× cpc (θc=26o) and 2.32× cpc (θc=26o), and (iii) 2.32× cpc (θc=59o) and 2.32× cpc (θc=26o), are computed from eq. (5). ()* = +, -./0 … (5) where qu, is the heat gain by the collector, and calculated from eq.(6). [11]: 12 = 34 56(78 − 79) …(6) the thermal efficiency of cpc can be described by ashrae standard 93-2010 [12], as demonstrated in eq.(5). if the thermal efficiency (the performance curve of cpc) from eq. (5) is plotted against the temperature difference between fluid inlet temperature and ambient temperature in relation with the solar irradiance received. the slope of this line represents the heat losses, and its intersection with the vertical axis is an indicator of the optical efficiency without thermal losses. 4. results and discussion the effects of various parameters on the optical and thermal performance of the cpcs are analyzed. the thermal efficiency results were obtained from ray tracing program for optical efficiency, and from outdoor experimental tests through the selected clear-sky days of june, december /2014 and january/2015, for test period extended from 9:00 to 14:00. the mass flow rate used in standard test is in the range between (0.0138-0.0277 kg/s) [12]. the mass flow rate used in the present work is (0.02 kg/s), measured by collecting water in a calibrated cylinder per time measured by a stop watch. 4.1. analysis of optical efficiency optical efficiencies and the angular acceptance at any given incident angle are shown in figures 8 and 9, respectively. fig. 8 presents the variations of optical efficiencies and the angular acceptance as the transversal projection angle θt varies, while θl is kept a constant of zero. for truncation, some rays incident at angles beyond the acceptance half-angle hit the receiver directly and others hit the receiver after reflection from the near side of the cpc while rays incident on the far side of the qussai jihad abdul-ghafour al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 1525 (2016) 20 cpc are rejected over the receiver. the optical efficiencies have a similar trend with the angular acceptance. however, the values of optical efficiencies are always lower than that of the angular acceptance at any transversal angle. average number of reflections has maximum value at normal incidence angle and decreases in the range (0o and ±θc). transversal projection angle θt (degree) -80 -60 -40 -20 0 20 40 60 80 o p tic a l e ffic ie nc y η o ( θ t,0 ) 0.0 0.2 0.4 0.6 0.8 1.0 a ng ul ar a cc ep ta nc e 0.0 0.2 0.4 0.6 0.8 1.0 opticla efficieny of 3.84× cpc (θc=20o) angular acceptance of 3.84× cpc (θc=20o) opticla efficieny of 3.61× cpc (θc=26o) angular acceptance of 3.61× cpc (θc=26o) opticla efficieny of 2.32× cpc (θc=59o) angular acceptance of 2.32× cpc (θc=59o) opticla efficieny of 2.32× cpc (θc=260o) angular acceptance of 2.32× cpc (θc=26o) fig. 8. the optical efficiencies and angular acceptance at different transversal projection angle. correspondingly, fig. 9 shows the effects on the optical efficiency as θl varies, while θt is fixed at zero. the major optical effects which might be presented in the longitudinal direction are those related with the angular variation of transmittance, absorptivity properties and with radiation spilling or end-mirror reflection effects. optical efficiency of 3.84× cpc (20o), 3.61× cpc (26o), 2.32× cpc (59o) and 2.32× cpc (26o) reduces slowly within the range of (-30o and +30o), (-35o and +35o), (50o and +50o), and (-40o and +40o), respectively. however, it decreases rapidly beyond this range except the optical efficiency of 3.84× cpc (20o), it decreases in the range (±30 and ±60) more than the decreasing in the range (-30o and +30o). the optical efficiencies of 0.684, 0.685, 0.723 and 0.723 at the normal incident angles can be received within the acceptance limit for the 3.84× cpc (20o), 3.61× cpc (26o), 2.32× cpc (59o) and 2.32× cpc (26o), respectively. the optical efficiency of cpcs has maximum value at normal incident angle due to minimum average number of reflections, and the last increases from (0o to ±90o) leads to decreasing the optical efficiency. incident angles of cpc collectors results are shown in fig. 10. longitudinal projection angle θl (degree) -80 -60 -40 -20 0 20 40 60 80 o pt ic al e ffi ci en cy η o (0 ,θ l) 0.0 0.2 0.4 0.6 0.8 1.0 optical efficiency of 3.84× cpc (θc=20o) optical efficiency of 3.61× cpc (θc=26o) optical efficiency of 2.32× cpc (θc=59o) optical efficiency of 2.32× cpc (θc=26o) fig. 9. the optical efficiencies at different longitudinal projection angle. qussai jihad abdul-ghafour al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 1525 (2016) 21 solar time (hh:mm) 09:00 10:00 11:00 12:00 13:00 14:00 15:00 in ci de nt a ng le s (d eg re e) -60 -40 -20 0 20 40 60 incident angle θ transversal projection angle θt longitudinal projection angle θl fig. 10. incident angles of cpc collectors versus solar time. 4.2. analysis of thermal efficiency 4.2.1. instantaneous thermal efficiency the efficiency of the cpcs for three cases described previously in section (2.2.1) are plotted in fig. 11, fig. 12 and fig. 13, during the test hours from 09:00 to 14:00 for different days under the same test conditions (inlet temperature, mass flow rate, total solar radiation and ambient temperature). for the first case, fig. 11 shows that the efficiency of 3.86× cpc (θc=20o) is almost lower than that of 2.32× cpc (θc=26o) during whole test hours. since, the optical efficiency of the 2.32× cpc is much higher than that of the 3.86× cpc. for second case, fig. 12 shows that the efficiency of 3.61× cpc (θc=26o) is lower than that of 2.32× cpc (θc=26o) with difference lower than that in the first case. here, the optical efficiency of 2.32× cpc is higher than that of 3.61× cpc and the last has optical efficiency little high than that of 3.86× cpc. for the third case, fig. 13 shows that the efficiency of 2.32× cpc (θc=59o) is close to that of 2.32× cpc (θc=26o). so, the optical efficiency of 2.32× cpc (θc=26o) has a good agreement with that of 2.32× cpc (θc=59o). local time (h) 09:00 10:00 11:00 12:00 13:00 14:00 in st an ta ne ou s th er m al e ffi ci en cy η 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 0.55 0.60 0.65 0.70 0.75 0.80 0.85 thermal efficiency for 2.32x cpc (26o) thermal efficiency for 3.84x cpc (20o) 21/01/2015 fig. 11. variation of instant. efficiency with time for 3.86× cpc (20o) and 2.32× cpc (26o). local time (h) 09:00 10:00 11:00 12:00 13:00 14:00 in st an ta ne ou s th er m al e ffi ci en cy η 0.25 0.30 0.35 0.40 0.45 0.50 0.55 0.60 0.65 0.70 0.75 thermal efficiency for 2.32x cpc (26o) thermal efficiency for 3.61x cpc (26o) 31/12/2014 fig. 12. variation of instant. efficiency with time for 3.61× cpc (26o) and 2.32× cpc (26o). local time (h) 09:00 10:00 11:00 12:00 13:00 14:00 in st an ta ne ou s th er m al e ffi ci en cy η 0.30 0.35 0.40 0.45 0.50 0.55 0.60 0.65 0.70 0.75 0.80 0.85 thermal efficiency for 2.32x cpc (26o) thermal efficiency for 2.32x cpc (59o) 30/12/2014 fig. 13. variation of instant. efficiency with time for 2.32× cpc (59o) and 2.32× cpc (26o). qussai jihad abdul-ghafour al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 1525 (2016) 22 4.2.2. the collector performance curves of cpcs before tests, the system is cleaned up and the pump is switched on for one hour until reaching steady state. after that, the temperatures of the inlet and outlet water and solar intensity are recorded. tests were conducted to generate the thermal efficiency curves of cpcs, two tests for every case. the performance curves of 3.86× cpc (20o) and 2.32× cpc (26o) are shown in fig. 14. the empirical equation of thermal efficiency of 3.86× cpc (20o) can be written as: ()* = −1.8667(79 − 7? @)⁄ ) + 0.5077 …(7) with r2=0.996 the empirical equation of thermal efficiency of 2.32× cpc (26o) can be written as: ()* = −3.4425(79 − 7? @)⁄ ) + 0.7203 …(8) with r2=0.996 (ti-ta / i) (k.m2/ w) 0.00 0.01 0.02 0.03 0.04 0.05 0.06 d ai ly t he rm al e ffi ci en cy η 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 results of 2.32x cpc (26o) results of 3.84x cpc (20o) η η η η = -3.4425 * (ti-ta/ i) + 0.7203 ηηηη = -1.8667 * (ti-ta/ i) + 0.5077 fig. 14. thermal efficiency curves of 3.86× cpc (20o) and 2.32× cpc (26o). the performance curves of 3.61× cpc (26o) and 2.32× cpc (26o) are shown in fig. 15. the empirical equation of thermal efficiency of 3.61× cpc (26o) can be written as: ()* = −2.0283(79 − 7? @)⁄ ) + 0.5196 ……...(9) with r2=0.966 the empirical equation of thermal efficiency of 2.32× cpc (26o) can be written as: ()* = −3.4449(79 − 7? @)⁄ ) + 0.6672 ……..(10) with r2=0.998 (ti-ta / i) (k.m2/ w) 0.00 0.01 0.02 0.03 0.04 0.05 0.06 d ai ly t he rm al e ffi ci en cy η 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 results of 2.32x cpc (26o) results of 3.61x cpc (26o) η η η η = -3.4449 * (ti-ta/ i) + 0.6672 ηηηη = -2.0283 * (ti-ta/ i) + 0.5196 fig. 15. thermal efficiency curves of 3.61× cpc (26o) and 2.32× cpc (26o). the performance curves of 2.32× cpc (59o) and 2.32× cpc (26o) are shown in fig. 16. the empirical equation of thermal efficiency of 2.32× cpc (59o) can be written as: ()* = −4.7044(79 − 7? @)⁄ ) + 0.6621 …(11) with r2=0.999 the empirical equation of thermal efficiency of 2.32× cpc (26o) can be written as: ()* = −3.9057(79 − 7? @)⁄ ) + 0.672 …(12) with r2=0.998 since, the higher thermal efficiency of the 2.32× cpc (26o) can be realized as a result of the better value of optical efficiency. (ti-ta / i) (k.m2/ w) 0.00 0.01 0.02 0.03 0.04 0.05 0.06 d ai ly t he rm al e ffi ci en cy η 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 results of 2.32x cpc (26o) results of 2.32x cpc (59o) η η η η = -3.9057 * (ti-ta/ i) + 0.672 ηηηη = -4.7044 * (ti-ta/ i) + 0.6621 fig. 16. thermal efficiency curves of 2.32× cpc (59o) and 2.32× cpc (26o). qussai jihad abdul-ghafour al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 1525 (2016) 23 4.2.3. the performance curve of 2.32× cpc (26o) the tests have been conducted over six clear sky days to generate the thermal efficiency curve of 2.32× cpc (26o), which is shown in fig. 17. the empirical equation of thermal efficiency of 2.32× cpc (26o) during six tests, can be written as: ()* = −4.6164(79 − 7? @)⁄ ) + 0.7095 …(13) with r2=0.81 (ti-ta / i) (k.m2/ w) 0.00 0.01 0.02 0.03 0.04 0.05 0.06 d ai ly t he rm al e ffi ci en cy η 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 results of 2.32x cpc (26o) η η η η = -4.6164 * (ti-ta/ i) + 0.7095 fig. 17. thermal efficiency curve of 2.32× cpc (26o). 4.3. effect of truncation on the performance of 3.86× cpc (20o) the truncation of cpc and its effect on the performance has been studied, for a number of reasons. first, the acceptance of beam and of diffuse insolation increases with truncation. second, the average number of reflections decreases, and hence the optical efficiency increases, with truncation. third, heat losses per aperture area increase with truncation. fig. 18 shows the variation of thermal efficiency, thermal losses and optical efficiency with the concentration ratio of 3.86× cpc truncated in three levels. as the concentration ratio decreases from (3.93× to 1×). three empirical equations for thermal efficiency, thermal losses and optical efficiency of 3.86× cpc have been found from experimental tests to predict the performance curve of cpc at any concentration ratio between (1×-3.93×). ()* = −0.0533 ∗ 5 + 0.6837 …(14) ij = −1.9186 ∗ 5 + 9.1274 …(15) (8 = −0.1036 ∗ 5 + 0.9012 …(16) the empirical equations above, are used for full cpc with acceptance half angle (15o). concentration ratio c 1.0 1.5 2.0 2.5 3.0 3.5 4.0 th er m al e ffi ci en cy η , o pt ic al e ffi ci en cy η o 0.4 0.5 0.6 0.7 0.8 0.9 1.0 th er m al l os se s u l (k .m 2 /w ) 0 2 4 6 8 thermal efficiency results thermal losses results optical efficiency results η η η η = -0.0533*c+0.6837 ul= -1.9186*c+9.1274 ηηηη οοοο = -0.1036*c+0.9012 fig. 18. variation of optical and thermal performance and thermal losses with the concentration ratio of 3.86× cpc (20o). 5. conclusions from this work, the following conclusions are drawn: 1. the comparative studies have shown that the optimum acceptance half-angle is (θc=26o) for full cpc, not for truncated one. 2. experimental results have shown that the maximum thermal efficiency of the full cpc with (c=2.32×) and (θc=26o) is 0.708. 3. the maximum thermal efficiency of the full cpc with (c=3.93×) and (θc=15o), when it's truncated to (c=3.84× and θc=20o), (c=3.61× and θc=26o) and (c=2.32× and θc=59o) are 0.51, 0.52 and 0.66, respectively. 4. the best concentration ratio of 3.93× cpc (θc=15o) is (c=2.32×) and (θc=59o). 5. comparative studies show that the 2.32× cpc (θc=59o) has a good agreement with the performance of 2.32× cpc (θc=26o). 6. empirical equations for optical and thermal efficiencies and thermal losses of 3.93× cpc (θc=15o) have been found over the concentration ratio. qussai jihad abdul-ghafour al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 1525 (2016) 24 notation aa aperture area, m2 c concentration ratio, dimensionless cp specific heat, j/kg. k it hourly total irradiation, j/m2 ṁ mass flow rate, kg/s qu useful heat gain, w ta ambient temperature, oc ti receiver inlet temperature, oc to receiver outlet temperature, oc ul heat loss coefficient, m2.k/w greek letters ηth thermal efficiency, dimensionless ηo optical efficiency, dimensionless θ incidence ingle, degree θc acceptance half-angle of cpc, degree θl longitudinal projection angle θl transversal projection angle 6. references [1] rabl a, ''solar concentrators with maximal concentration for cylindrical absorbers''. applied optics, vol. 15, pp. 1871-1873, 1976. [2] kalogirou s. a, ''solar energy engineering processes and systems'', (2nd edition), academic press, san diego, 2014. [3] mcintire w. r, ''truncation of non-imaging cusp concentrators''. solar energy, vol. 23, pp. 351-355, 1979. [4] gordon j. m., carvalho-pereira m., rabl a., and winston r, '' truncation of cpc solar collectors and its effect on energy collection''. solar energy, vol. 35, pp. 393-399, 1985. [5] suzuki a., and kobayashi, s, ''yearly distributed insolation model and optimum design of a two dimensional compound parabolic concentrator''. solar energy, vol. 54, pp. 327-331, 1995. [6] winston r., and o'gallagher j, '' nonimaging concentrators'', in: meyers, r. ed, encyclopedia of physical science and technology, ch. optics, pp. 507-522, academic press, san diego, 2004. [7] tang r., wu m., yu y, and li, m, ''optical performance of fixed east-west aligned cpcs used in china''. renewable energy, vol. 35, pp. 1837-1841, 2010. [8] budihardjo i., morrison l, ''performance of water-in-glass evacuated tube solar water heaters''. solar energy, vol. 83, pp. 49-56, 2009. [9] kim y. s., balkoski k., jiang l., and winston r, ''efficient stationary solar thermal collector systems operating at a medium-temperature range''. applied energy, vol. 111, pp. 1071-1079, 2013. [10] trace pro manual. [11] garg, h. p., and prakash, j, ''solar energy fundamentals and applications'', (1st revised edition), tata mcgraw-hill, new delhi, 2008. [12] ashrae standard 93-2010, ''method of testing to determine the thermal performance of solar collectors'', american society of heating refrigerating and airconditioning engineers, atlanta, ga, 2014. �� 1، ا���د����12 ا���ارز�� ا� ����� ا�������� � �د � ا����ر ��2016( 1525، ( 25 �2 1-0 �/. ُ�-�,+ ُ�#'َّ( ُ�#'ِّ% درا�� $�#" �� !داء �3�1 435 *��� � �د �ا����ر %"% ����** � ا������ ا���������� ** ،*� ا�%�$#� ا�"��!�! �� /� kaisyqj@yahoo.com: ا�+)*� ا(��")و�&* mohammedeng37@gmail.com: ا�+)*� ا(��")و�&** ا��6�� ���� ا�ُ�)a�b cd/ �+َّ9 �@? ُ$��4<ا� ُ�)9ِّ;ات-)8�9 وا�"5�67 4& درا�� -%)*+�� (0��1 $0 ا�، -� /)ض -,���f يذ &i!+أ� �d"�$ .6�� أداء !-* ����q"��i 0ام ا�����6ت ا�"%)*+�� 4& ا��!اء ا�@��i 5d 4& ذ�o ا���nءة ا�7)ار*� ا���l7dا��)9;*0 �fا�. #i 0*;9(ر ا���+"rا �-���"�+s� ك("f$ aھ�� cd/ . v*( ا )راتا�#�*� $0 ا�+"r a�#ا ا�w4& ھiع�@"�� y9�/ 0$ �zا��)9;*0 وا �nd"q$ ت�*!"�$ �1[1 &4 . (��\� ).θc(ا�6+!ل زاو*� �,[��a ا�"@�ع �& /a�b cd �@? ُ$��4< $)89ا� ُ�)9ِّ;ات�d ا��#��ر*�6+!ل و�,[ زاو*� ا��f !26(ھo .( ت�*!"��,[ زاو*� 3و 2و �d 1)9; ا���s&�"@�ع �ا(�� cpc، وθc = 26o 0�i)( cpc×2.32 و ) θc = 20o( cpc ×3.86ا�n)ق 0�i ا���nءة ا�7)ار*� ا���l7d ل ./cd ا�"!ا�& 59o و620o ، 26o+!ل v��9 ا� ×3.61 )θc = 26o (و cpc×2.32 (θc = 26o) abل . ھ! 4)ق 9+�) ووا ��l7dءة ا�7)ار*� ا��n0 ا���i ق(nأن ا� dz!�cpc × (θc = 59o) 2.32 �9ن أ/��l7dcpc×2.32 (26o) cd ل ھ! اr"]ف f\�) $�6ر�� $? ا�n)ق 4& ا��7(ت اeو�c وا�����s، وا���nءة ا�7)ار*� ا� cpc×2.32 (θc = 26o)و ��� ا�s]�1 اre)ى�f9;ات ا�(�d� &"ا� od0$ . ار*� ل(z ءة�n9 c,�ا�"%)*+�� أن أ ij�"ت ا��(�، أ�,c 0.708ا���$a $�6ارھ� ) cpc×2.32 )26oأظ ، 0.51$�6ارھ� cpc ×2.32 (59o) و cpc ×3.84 (20o) ،cpc ×3.61 (26o)، /��$� *�!ن $6"@#� إ��n9cpc ×3.93 (15o) cءة z)ار*� ل ��j) ا�7)ار*� وا���nءة ا�+,)*� ازدادت $0 )×1ا�6�i)×3.93 c,�ن ��+� ا�")cd/ . 0$ ;�9 ا�"!ا�& 0.66و 0.52qءة ا�7)ار*�، ا��n(0.47 ، ا�� cا� (0.63، 1.58) cا� (7.2 k.m2/w 0.494 و) c0.797).ا� (microsoft word 5563 \310\324\307\321 \335\307\312\315 \346\307\343\314\317) al-khwarizmi engineering journal al-khwarizmi engineering journal,vol. 13, no. 3, p.p. 5563 (2017) performance comparison of different advanced control schemes for glucose level control under disturbing meal bashar fateh midhat* amjad jaleel humaidi** *,**department of control and systems engineering / university of technology *email: basharfm88@yahoo.com **email: aaaacontrol2010@yahoo.com (received 30 october 2016; accepted 7 march 2017) https://doi.org/10.22153/kej.2017.03.003 abstract in this work, diabetic glucose concentration level control under disturbing meal has been controlled using two set of advanced controllers. the first set is sliding mode controllers (classical and integral) and the second set is represented by optimal lqr controllers (classical and min-, ax). due to their characteristic features of disturbance rejection, both integral sliding mode controller and lqr minmax controller are dedicated here for comparison. the bergman minimal mathematical model was used to represent the dynamic behavior of a diabetic patient’s blood glucose concentration to the insulin injection. simulations based on matlab/simulink, were performed to verify the performance of each controller. in spite that min-max optimal controller gave better disturbance rejection capability than classical optimal controller, classical sliding mode controller could outperform min-max controller. however, it has been shown that integral sliding mode controller is the best of all in terms of disturbance rejection capability. key words: optimal lqr control, optimalminimax control, sliding mode control, integral sliding mode control. 1. introduction diabetes mellitus is the human disease which results from the presence of high level of blood sugar for prolonged period due to inadequate generation of insulin in blood [1]. in human body, the beta cells in pancreas are responsible for producing the insulin, which regulates the glucose consumption. in diabetes, beta cells fails to produce enough insulin concentration in blood and the human body will be unable to control the blood glucose level. type i diabetes mellitus patients cannot produce any insulin and insulin shots are given several times a day to help regulate their blood glucose level. a typical patient is then serving himself as a control system [2]. on the other hand, any patient that suffers from diabetes and not receives the insulin cure properly can lead to complications such as nerve damage, brain damage, amputation and eventually death. in the human body, the normal blood glucose level varies in a narrow range (70-110) mg/dl. the diabetes is diagnosed if the human body is not able to control the normal glucose-insulin interaction [3]. for this reason, the blood glucose must be regulated by injecting the insulin [4]. in general, the closed loop glucose regulation system requires three components, which are: glucose sensor, insulin pump and control method for determining the necessary insulin dosage based on the glucose measurements [5]. figure (1) shows the block diagram of closed loop glucose control system. bashar fateh midhat al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 5563 (2017) 56 fig. 1. block diagram of closed loop insulin regulation system [10]. several approaches have been previously addressed to design the feedback controller for insulin delivery, such as classical methods like proportional integral derivative (pid) controllers [6, 7] and pole placement [8], which require a linearized mathematical model for the design of the controller, as well as model predictive control (mpc) [9, 10]. in [6] a pid controller based on bp neural networks is proposed in order to reduce the time of lowering blood glucose. in [11], the parameters of hammerstein controller were optimized in order to minimize the time that takes for blood glucose to come back to its basal level. also there are some efforts to use model independent based controller such as fuzzy controllers. in [12], a closed-loop control system applying fuzzy logic control introduced and the performance of this controller is tested on three different diabetic patients. maryam [13] tried to tune the pd fuzzy controller with pso algorithm. these fuzzy controllers were just able to control the glucose concentration, and suffer from lack of insulin and pump control. the works referred in [14, 15] suggested robust controllers such as disturbance rejection lq controller, �� and �� controller to regulate glucose-insulin system for type i diabetic patients under meal disturbance. in this paper, four different controllers (optimal lqr, minimax optimal, sliding mode, integral sliding mode) are addressed and designed for the glucose concentration level control problem in diabetic patients under meal disturbance. 2. mathematical model bergman minimal mathematical model, which is the most common referenced model in the literature, approximates the dynamic behavior of a diabetic patient’s blood glucose concentration to the insulin injection. the main advantage of using bergman minimal model is that the number of parameters is minimum and it describes the relation between main two factors, insulin and glucose concentrations, without getting into biological complicated details. in the present work, nonlinear three-state minimal model of bergman is considered [7]; �� ��� = −������ − �������� + ��� + ℎ��� � ��� = −�� ��� + ������ �� ��� = −������� + ��� + ���� ��⁄ …(1) where g(t) is plasma glucose deviation, [mg/dl], x(t) is remote compartment insulin utilization, [1/min] and y (t) is plasma insulin deviation, [mu/dl]. the control variable ���� is the exogenous insulin infusion rate (mu/min), while the disturbance ℎ ��� represents the exogenous glucose infusion rate (mg/dl min). the physical parameters ��and��are the basal glucose level (��/��), and basal insulin level (��/��), respectively, and ��is the insulin distribution volume (��). the model parameters are: �� �1 �� ⁄ �, �� �1 �� ⁄ �, �� ��� ��� �� �⁄ �� and �� �1 �� ⁄ �. if the unmeasurable variable ��� is assumed a slow variable, then � ��� = 0. from eq.(1), the expression ��� = ���/��� � ��� can be found. substitution this expression into the first equation, the model of eq.(1) is reduced to the following [13]: �� ��� = −������ − ���� ��������� + ��� + ℎ��� �� ��� = −������� + ��� + ���� ��⁄ …(2) the linearization of eq.(2) is performed by taking the variation of ���� = �" + ∆���� and ���� =�" + ∆����around equilibrium points (�", y0, ℎ", �"). the perturbed version of eq.(2) is given by; ∆�� = $−�� − ���� �"% ∆���� − ��& + ��� ���� ∆���� ∆�� ��� = −�� ∆���� + ∆ ���� ��⁄ …(3) if∆���� is defined as the first state variable'����, ∆���� is set as second state variable '���� and(��� is assigned to control input variation∆����, then the previous equation can be written in the following state space form, )� ��� = *−�� − �� �"�� − ��& + ��� ����0 −�� + )��� + , 01 ��⁄ (��� + .10/ ℎ��� …(4) 0��� = .1 00 1/ )��� bashar fateh midhat al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 5563 (2017) 57 for control objectives, the linearization in state space of the above model is taken at the equilibrium points of the following specified values; ℎ" = 0, �" = ������, �" = 0 therefore, the obtained linearized model can be written as; '� ��� = *−�� − �� ����0 −�� + '��� + ,10 01 ��⁄ (1��� 2��� = .1 00 1/ '��� + …(5) where (1��� = 3ℎ��� (���45. equation(5) can be written in compact form as; '� ��� = 6 '��� + 7 (��� …(6) 2��� = 8 '��� it is easily to show that the linearized model is completely controllable. 3. controller design four structures of advanced controllers will be presented and designed here for controlling the glucose level in human blood under meal disturbance. later, the performance of such controllers will be verified and compared to each other using matlab/sumlink. 3.1. sliding mode controller sliding mode control is a discontinuous feedback control forces the system states to reach and remain on a specific surface within the state space (called sliding surface). the first stage of design is the selection of the discontinuity surface such that sliding motion would exhibit desired properties. let us define a surface 9 in the state space as follows [16, 17]; 9 = '� + : '� …(7) if a controller ( was designed to make the system trajectories head to the surface 9 = 0, then eq.(7) can be written as, '� + :'� = 0 …(8) from eq. (5), one can find that '�� = −��'� − ����� ��⁄ �'� …(9) rearranging the above equation results in '� = − �����'� + '��� ������⁄ …(10) substituting '� from the above equation into eq.(8) results in − �����'� + '��� ������⁄ + :'� = 0 …(11) or, '�� + ��� − : ���� ��⁄ �'� = 0 …(12) the time solution for the equation above is written as '� = '��0�;<�=><? @a=b =c⁄ � 1 …(13) such that ��� − : ���� ��⁄ � d 0. equation (13) shows that if the state trajectories are forced to move on surface 9 = 0, then '� will tend to zero exponentially after a finite time interval or one can say, '��� = ∞� = 0 → ���� = 0 ...(14) to ensure that the state trajectories will head toward the surface 9 = 0, the following reaching condition should be fulfilled 99� g 0 …(15) since 9� = '�� + :'��, then 99� = 9 3'�� + :'��4 = 9 3−��'� + (��� ��⁄ − ��'� −��� ���⁄ '� + ℎ���4 …(16) if one assumes that the control defined as a discontinuous function for the surface 9 as below (��� = −h ∗ 9�� �9� …(17) substituting for the control(��� in eq.(16), we have 99� = −�� 9 '� − h 9 9�� �9� ��⁄ −��9 '� − ��� ��⁄ � 9 '� + 9 ℎ��� …(18) using the fact that 9 ∗ 9�� �9� = |9| and from linear algebra, the inequality kl m |k||l| holds and results in the following; 99� m |9| n|��||'�| − h ��⁄ + |��||'�| +|�� ��⁄ |'� + |ℎ���|o g 0 …(19) solving for h, we have h d �� n|��||'�| + |��||'�| + |�� ��⁄ |'� +|ℎ���|pqro …(20) 3.2. integral sliding mode control for disturbance rejection in what follows, integral sliding mode controller is designed for control and disturbance rejection of glucose systems. starting with rewriting the control law as follows, ( = (& + (� …(21) where(& is designed to make the system follows a specified trajectory '& in the state space which is based on optimal lqr controller, while the design of (� is dedicated to cancel the disturbance ℎ���. rewriting eq.(4) by separating the control input ���� from disturbance ℎ��� and then substituting the control signal from eq.(21) to have; )� = 6 '��� + 7s(&��� + 7s(���� + t ℎ��� …(21) wheret = 31 045 and 7s = 30 1 ��⁄ 45. bashar fateh midhat al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 5563 (2017) 58 the first stage of design is to select the discontinuity surface 9 such that sliding motion would exhibit desired properties. the surface 9 is defined in the state space as follows 9 = 9& + u …(22) whereu represents the integral part which cancels the disturbance and 9& represent the desired path in the state space given by 9& = 8 ' …(23) in order to keep the system on the specified trajectory 9& the time derivative of the surface 9 should equal zero. in other words, the system trajectory will not leave the surface 9&. 9� = 9�& + u� = 0 = 8'� + u� = 0 …(24) or, 9� = 836 '��� + 7s(&��� + 7s(���� + t ℎ���4 + u� = 0 …(25) in order to ensure that 9��� = 9&��� for all � d 0 the following condition should be fulfilled7s(���� = −t ℎ��� …(26) substitute in 9� we get u� = −8 36 '��� + 7s(&���4 …(27) or, u = −8 v 36)��� + 7s(&���411w �� …(28) thus, substitution for u is the surface equation 9 will ensure that the system trajectories will remain on the surface 9 even under external disturbances. if (� considered to be a nonlinear function, then (� = −h� 9�� �9� …(29) whereh� is the discontinuous controller gain. the final control law can be rewritten as follows; ( = (& + (� ( = −x ' − h� 9�� �9� …(30) to ensure that 9� = 0 for ∀� ≥ 0 in eq.(25), the following condition has to be satisfied 87s(���� = −8 t ℎ��� …(31) multiplying out the matrices in the above equation results in, − h�9�� �9� ��⁄ = ℎ��� …(32) taking the worst case disturbance ℎ���pqr, the integral sliding mode gain h� can be evaluated as follows h� ≥ �� ℎ���[\] …(33) 3.3. optimal lqr control the requirement of classical lq control method is to minimize the following quadratic cost functional: ^�(���� = �� v n25_ 2�& + (5` ( o �� …(34) the classical lq attempts to find an optimal (∗���, � ∈ 30, ∞4 such that ^�(∗���� m ^�(��� for all (���, � ∈ 30, ∞4 under properly chosen c and _. the matrix _ (n×n) and ` (m×m) are selected by the design engineer. the first element of input vector is the insulin rate ����, and the second element is the exogenous glucose ℎ��� which stands for disturbance. the objective is to minimize the effect of disturbance on the output. however, the elements of diagonal matrix c are responsible for overweighting and underweighting of the input elements. the first component of matrix c, namely c��, is chosen to give high importance to disturbance input, ℎ���, while the element c�� has to giveless importanceto insulin rate. less importance to insulin means that we relief the constraint on insulin or permit it to take higher level. therefore, high value is assigned to c�� and low value is assigned to c��. on the other hand, the elements of _give the weights on system outputs, plasma glucose deviation and plasma insulin deviation. normally in this application, the same weight is given to both outputs. based on optimal control theory, the following control riccatiequation is established as [18], d6 + 65d + 858 − d75`<�7 d = 3e4 …(35) since matlab package is used here, a special builtin function called care is used to solve above ricatti equation for matrix d. positive definiteness of matrix d is a necessary condition of solution. the optimal solution can be found in terms of d-matrix as follows; (∗��� = −`<�75d)∗��� …(36) the closed-loop system based on optimal control input is given by [18]; )� ∗��� = 36 − 7 f4)∗��� …(37) where f = `<�75d. the closed-loop system will exhibit different performance depending on how design parameters are selected. generally speaking, selecting _ with large terms means that, to keep gsmall, the state )��� must be smaller. on the other hand selecting ` with large terms means that the control input (��� must be smaller to keep ^ small. this means that larger values of _ generally result in the closed loop poles of the system matrix �6 − 7f� being further left in the s-plane so that the state decays faster to zero. on the other hand, larger c means that less control effort is used, so that the poles are generally slower, resulting in larger values of the state )���. bashar fateh midhat al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 5563 (2017) 59 3.4. optimal lqr control with disturbance rejection (minimax) the disturbance rejection lq method is a generalization of classical lq method and is based on the minimax criteria. this techniques is dedicated for optimal control and disturbance rejection puposes. figure (2) shows the general structure of disturbance rejection lq (minmax) control strategy. the system dynamic given by eq.(4) is reformulated by separating the control input ���� from disturbance ℎ���. therefore, the dynamic system can be written as; '� = 6 '��� + 7s ���� + t ℎ��� …(38) 2��� = 8 '��� + h ( where7s = 31 1 ��⁄ 45 andt = 31 045 . fig. 2.general structure of minimax control [15]. in this case, the quadratic cost functional will be modified with the disturbance explicitly ^i����j = 12 l n25��� 2���� & + �5��� ���� −m�ℎ5��� ℎ��� o �� …(39) wherem is a design parameter, which is concerned in system stability analysis. it is clear that the disturbance tries to maximize the cost, so it appears with negative sign. meanwhile, the objective is to find a control ���� that could minimize the maximum cost achievable by the disturbance. the unique solution of cost function, �∗���andℎ∗���, exists and satisfies the saddle point condition, ^ i�∗���, ℎ���j m ^ i����, ℎ∗���j m ^ i�∗���, ℎ∗���j …(40) where�∗��� is the optimal control and ℎ∗��� is the worst-case disturbance. these functions can be computed as: �∗��� = −7s5d)��� ℎ∗��� = �1 m�⁄ �t5 '��� …(41) whered is positive symmetric matrix. the numeric values of matrix entries are determined by the solution of the following modified control riccati equation (mcre); d6 + 65d + 858 − d�7s57s − tt5�d = 304 …(42) to solve riccatiequation using matlab built-in care function, the structure of above riccati equation is modified to be rewritten as d6 + 65 − d3t7s4 ,−m� 00 1-<� 3t57s54d +858 = 304 …(43) where, ` = ,−m� 00 1and n = 3t7s4. the re described by eq.(43) finds a straightforward solution with the help of care function as indicated in appendix (a). 4. simulation results both sliding mode and optimal lqr controllers have been applied to the diabetic model. the effectiveness and robustness of suggested controllers are assessed using simulation results based on matlab-simulink (ra2012). figure (3) shows meal disturbance function behavior, which represents the exogenous glucose infusion. figure (4) shows the simulink modeling of sliding and optimal controllers for controlling the glucose level against disturbing meal. the meal disturbance is saved inside a look-up table (see appendix b). fig. 3. disturbance meal function (exogenous glucose infusion). 0 200 400 600 0 0.2 0.4 0.6 0.8 1 1.2 time(min) h (t ) (m g /d l⋅m in ) bashar fateh midhat al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 5563 (2017) 60 fig .4. matlab-simulink modeling of sliding mode controller and optimal controllers. the model parameters are listed below [15]: �� = 0.028, �� = 0.025, �� = 0.00013, �� = 0.093, �t = 110, �t = 1.5, �& = 16.67. based on the above values, the design parameter f is calculated using eq.(13). then, the value of f is equal −2.23. for the optimal lqr controller, the matrices `and _ are set at the following values; ` = ,1 00 1 1000⁄ -, w = ,1 1000⁄ 00 1 1000⁄ -, considering the above d = . 0.0140 −0.0560−0.0560 0.3130 / then, it is easily to find the optimal gain matrix f f = . 0.0000 −0.0001−0.4664 2.6086 / based on critical value of m = 17.086, which lead to positive definite matrix solution and stable closed loop system, the matrix y resulting from eq.(31) is given by d = . 3.5822 −3.2982−3.2982 7.02982 / this gives the following feedback gain matrix f = . 0.0123 −0.0113−27.4853 58.5570 / to determine the stability of the system one can easily substitute the values of gain matrix kinto the closed loop equation represented by eq.(5) and find the location of the closed loop as in the following manner: )� = �6 − 7f�) then, the eigenvalues of the matrix (6 − 7f) are the roots of the characteristic equation which calculated as follows [18] |z{ − 6 + 7f|= |.z 00 z/ − .−0.0280 −0.5720 −0.093/ + ,1 00 1/120. 0 0−0.4664 2.6086/| = }.z + 0.0280 −0.5720 z + 0.093/ + . 0 0−0.0039 0.2174/} = }.z + 0.0280 −0.572−0.0039 z + 0.3104/} solving for λyields λ� = −0.361, λ� = −3.023 repeating the same procedure for the optimal minimax controller we get z� = −0.503, z� = −5.587 initially, both controllers have the roots in the left hand of the s-plane meaning that the system under the proposed controllers is stable. however, it can be noted that with the optimal minimax controller the roots lie further from the origin resulting in more stable performance and a faster response. figure (5) shows the glucose level under meal disturbance of figure (2) with different four controllers. the figure shows that the glucose level reaches 136 (mg/dl) when using classical optimal lqr controller. this stands for 12.36% above basal glucose level. however, minimax optimal controller could reduce the maximum value of glucose level to reach to 125 (mg/dl), which is about 11.36% above the basal level. sliding mode controller (smc) gives better performance than both optimal controllers. with this controller, the maximum glucose level does not exceed 123 (mg/dl); i.e, the controller permits 11.18% change over the basal glucose level. it is evident from the figure that integral sliding mode controller shows the best robustness characteristics than all the above controllers. the percentage change of ismc is approximately 10.63% above the basal level which is the minimum percentage than others. t time table in insulin input h h(t) g glucose level -cbasal insulin level switch in1 in2 out1 lqr 1/s integrator2 1/s integrator1 1/s integrator g y z uo u1 dz fcn integral sliding mode g y h i dg dy fcn glucose model 110 gb clock bashar fateh midhat al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 5563 (2017) 61 fig. 5. plasma glucose level figure (6) shows the insulin rate resulting from each controller. it has been shown that the more robust controller, the higher level of insulin rate which is taken by human body. this physically indicates that more robust controller of requires more insulin rate to be injected; this is the price of robustness. fig. 6. plasma glucose level. 5. conclusion in this paper, different controllers were addressed for the problem of blood glucose concentration level control. simulation was performed using matlab/simulink in order to investigate the performance of suggested proposed controllers under a meal disturbance. the four designed controllers could successfully control the glucose level successfully and retain the glucose level back to its basal level. however, the simulation has showed relative differences in the performance of addressed controllers. it can be noted that the integral sliding mode gives the best disturbance rejection capability over other controllers such that it prevents the glucose level to exceed 118 mg/dl. moreover, sliding mode controller outperforms the characteristics of minmax controllers. the latter could keep the glucose level within 125 mg/dl. however, it can be seen that the optimal lqr controller have the worst performance where the glucose level reaches the value of 135 mg/dl. from fig. (6), it can be concluded the price of getting better control performance is the increased level of insulin infusion in order to counteract the glucose evolution. therefore, it can be noted that the integral sliding mode has the highest insulin infusion compared to the other controllers, while the lowest level is shown in lqr controller. 6. references [1] bergman r.n., philips l.s., cobelli c., "physiologic evaluation of factors controlling glucose tolerance in man, journal of clinical investigation," vol.68, pp. 1456–1467, 1981. [2] o. vega-hernandez, d. u. campos-delgado, and d. r. espinoza trejo, "increasing security in an artificial pancreas: diagnosis of actuator faults," proc. of pan-american health care exchanges conference, mexico city, mexico, pp. 137-142, 2009. [3] v. r. kondepati and h. m. heise, "recent progress in analytical instrumentation for glycemic control in diabetic and critically ill patients, "anal bional.chem., vol. 38,pp. 545563, 2007. [4] thomson, s., d. beaven, m. jamieson, s. snively, a.howl and a. christophersen, "type ii diabetes: managing for better health outcomes," in pricewater house coopers report, diabetes new zealand inc., 2001. [5] topp, b., k. promislow and g. de vries, "a model of �-cell mass, insulin and glucose kinetics, "pathways to diabetes. j. theor. bio, pp.605-619, 2000. [6] c. li and r. hu, "pid control based on bp neural network for the regulation of blood glucose level in diabetes", in proceeding of the 7th ieee international conference on bioinformatics and bioengineering, boston, pp. 1168-1172, 2007. [7] chee f, fernando tl, savkin av, heeden vv. "expert pid control system for blood 0 200 400 600 15 20 25 30 35 time (min) i( t) ( m u /m in ) lqr minimax smc ismc 0 200 400 600 105 110 115 120 125 130 135 140 time(min) g (t ) (m g /d l) lqr minimax smc ismc bashar fateh midhat al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 5563 (2017) 62 glucose control in critically ill patients," ieee transactions on information technology in biomedicine, pp.419– 425, 2003. [8] salzsieder e, albrecht g, fischer u, freyse ej. "kinetic modeling of the glucoregulatory system to improve insulin therapy," ieee transactions on biomedical engineering, vol.32, pp.846–855, 1985. [9] parker r.s., doyle f.j., peppas na., "a model-based algorithm for blood glucose control in type i diabetic patients," ieee transactions on biomedical engineering, vol.46, no.2, pp.148–157, 1999. [10] s. m. lynch and b. w. bequette,"model predictive control of blood glucose in type i diabetes using subcutaneous glucose measurements, "in proceedings of the american control conference, u.s.a, pp. 4039–4040, may 2002. [11] k. beyki, m. dashti javan, k. shojaee and m.m. neshati, "an intelligent approach for optimal regulation of blood glucose level," in 17th iranian conference of biomedical engineering, pp.1-5, 2010. [12] s. yasini, m.b. naghibi-sistani and a. karimpour, "active insulin infusion using fuzzy-based closed-loop control", in 3rd international conference on intelligent system and knowledge engineering, mashhad, iran, pp. 429-434, 2008. [13] d. n. maryam abadi, a. alfi, m. siahi, "an improved fuzzy pi controller for type 1 diabetes," research journal of applied sciences, engineering and technology, vol.4, no.21, pp. 4417-4422, 2012. [14] levente kovacs, béla palancz, endre borbely, "robust control algorithm for blood glucose control using mathematica," acta electrotechnicaet informatica, vol. 10, no. 2, pp. 10–15, 2010. [15] levente kovacs, béla palancz, "glucoseinsulin control of type1 diabetic patients in �� ��⁄ space via computer algebra," 2nd international conference, australia, july, 2007. [16] vadim utkin, jürgen guldner, jingxin shi, "sliding mode control in electromechanical systems," crc press, 2009. [17] jinkun liu, xinhua wang, "control for mechanical systems design, analysis and matlab simulation," tsinghua university press, beijing and springer-verlag berlin heidelberg, 2012. [18] donald e. kirk, "optimal control theory: introduction, "dover publications, inc., 1998. appendix (a) matlab function of solution of equation (12), using care function; gama=17.086; c=[1 0]; q=c'c l=[1;0]; bu=[0; 1/120]; b=[l bu]; r=[-gama^2 0; 0 1]; pm=care(a,b,q,r) km=inv(r)*b'*pm appendix (b) the table below lists the data of disturbing meal behavior table 1, disturbance meal function time (t) [min] glucose (h(t)) [mg/(dl.min] 0 0 25 0.185 50 0.495 75 0.765 100 0.975 125 1.15 150 1.07 175 0.82 200 0.575 225 0.335 250 0.225 275 0.145 300 0.098 325 0.06 350 0.035 375 0.02 400 0.01 450 0.005 1000 0 )2017( 55-63، صفحة 3د، العد13دجلة الخوارزمي الهندسية المجلم بشار فاتح مدحت 63 تحت تاثير جسم البشريالمقارنة االداء بين مسيطرات متقدمة للسيطرة على مستوى السكر في االضطراب الغذائي **امجد جليل حميدي *مدحت بشار فاتح الجامعة التكنولوجية/ قسم هندسة السيطرة والنظم*,** basharfm88@yahoo.com :البريد االلكتروني* aaaacontrol2010@yahoo.com :البريد االلكتروني** الخالصة السيطرة على تركيز الكلوكوز في الجسم البشري وذلك باقتراح نوعين من المسيطرات: المسيطرات المثالية والمسيطرات ذات النمط تتم البحثفي هذا ن من المسيطرات المثالية التي تم ابخواص تقليل تاثير االضطراب المسلط على المنظومة. هناك نوعن من المسيطرات االنوع ذانهمتاز . اذ ياالنزالقي العليا. اما النوع االخر فتم استخدام مسيطرين ذات النمط االنزالقي وهما -طريقة الدنياالوهي المسيطر المثالي التقليدي والمسيطر الذي يستند على احاها اقتر المسيطر التقليدي والتكاملي. فان المسيطر ذات النمط االنزالقي التكاملي قد اظهر خواص ،قد اعطى نتائج جيدة العليا-بالرغم من ان المسيطرالمثالي الذي يستند على الطريقة الدنيا وجبة طعام. على شكل والتي تم تمثيلها المسلط افضل من المسيطرات المقترحة وذلك من ناحية تقليله تاثير االضراب (microsoft word \316\355\321\355\31119-28) al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 14, no. 1, march, (2018) p.p. 19-28 microstructural characterization and mechanical properties of similar and dissimilar al alloys joined using friction stir welding kharia salman hassan department of mechanic technician/ institute of technology -baghdad email: almaden20002000@yahoo.com (received 7 february 2017; accepted 3 august 2017) https://doi.org/10.22153/kej.2018.08.002 abstract the influence of preshot peening and welding parameters on mechanical and metallurgical properties of dissimilar and similar aluminum alloys aa2024-t3 and aa6061-t6 joints using friction stir welding have been studied. in this work, numbers of plates were equipped from sheet alloys in dimensions (150*50*6) mm then some of them were exposed to shot peening process before friction stir welding using steel ball having diameter 1.25 mm for period of 15 minutes. fsw joints were manufactured from plates at three welding speeds (28, 40, 56 mm/min) and welding speed 40mm/min was chosen at a rotating speed of 1400 rpm for welding the dissimilar preshot plates. tow joints were made at rotational speed of 1000 rpm and welding speed of 40m/min from shot and without shot peening plats. welding temperature was measured in three zones using thermocouple. micro hardness (hv) and tensile tests were performed to evaluate the mechanical characteristic of the joints. the results show a decay in mechanical qualities when the welding speed was increased and the best result was at (28) mm/min and the opposite result was obtained when rotational speed increased and pre-shot contributed in improving of this decay at 88% of welding speed (40) mm/min and 98% at the rotational speed of 1000 rpm. key word: friction stir welding (fsw), heat input, maximum temperature, mechanical properties, shot peen. 1. introduction the connection of dissimilar materials based on significant engineering uses just "power generation", petrochemical, chemical, nuclear, aerospace transportation and electronic manufactures, the connection of dissimilar materials gift additional defiance and difficulties than similar by using friction stir welding due to the probability of the realization of "brittle intermetallic phases" and little period of eutectics dissolution [1].friction stir welding (fsw) is a method in solid stat include embrace the ascent of a spinning hard steel nail broadens by a cylinder-shaped shoulder between two contacting metal plates [2]. friction stir welding (fsw generated heat which made the material softer about the pin and transfers from the front of the pin to the back because the revolution and transfer of the tool, here join caused through the mutual action of frictional heating among tool and weld sheet plastic deformation. the method formed heat in percentage 95% which is remain in the work parts and just 5% flows in the tool. during friction stir welding method quality is determined and controlled by the resultant heat which is rely on parameters like rotational speed, welding speed, and plunge depth while the rotating pin deforms the heated material. [3,4 ]. friction stir welding induces dynamic recrystallization and recovery that refines microstructure of the stir region. therefore friction stir welded joints have amended kharia salman hassan al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 1928 (2018) 20 mechanical qualities like tensile strength, ductility, hardness compering with fusion welded joints [5]., structure of weld, due to hard mechanical stresses shows three clear microstructural zones on the transverse cross section of the fsw joint, .these zones are a nugget, or stirred zone, thermo-mechanical affected zone (tmaz), and a heat affected zone (haz) ,nugget zone nz is a region through which tool pin passes and thus experiences both high deformation and heat treatment. it generally consists of very fine equiaxed [6]these change in microstructures cause decay in mechanical characteristic this decay can improve by using one of mechanical surface treatments such as a cold working process (shot peening) in which small spherical shots the surface of plat produce compressive residual stresses and extremely high dislocation densities near the faces films consequent inhomogeneous plastic deformations[7] the figure of effective factors on the shot-peening method is: type, size and shape of the shots, peening time, torrent speed, air pressure on the peened element, distance from nozzle to material surface (peening distance), nozzle angle, peening intensity and face covering percentage[8]many, researchers studied the subject such as: saad ahmed khodir[9 ] studied the impact of apportionment revolution velocity and stable place of material on" microstructure", tensile characteristic and" hardness" apportionment for disparate aluminum alloys joints for 2024-t3 and 7075-t6 create by fsw at invariant welding speed of 100 mm/min and variable rotation speeds of 400, 800, 1200, 1600 and 2000 rpm and he clear that the weld joint at rotation speed 400 rpm was weak due to no mixed between metals and when increasing it to 1600,2000 the metal was melted remaining many defects due to solidification and he show that the best result at rotation speed 1200 rpm. moreira [10 ] studied the a metallurgical and mechanical quality of disparate of aluminum alloy 6061-t6 with 6082-t6 of friction stir welded butt joints and contrast the result of its with butt joints of alike material. microstructure examination, micro hardness, tensile and bending examinations of joints were performing. it was exist that friction stir welded of aa6082-t6 offer lesser yield and ultimate stress while the disparate joints show intermediate characteristics. the disparate joints also displayed the intermediate in tensile tests. and in hardness profile the lesser values were gotten in the aa6082-t6 alloy plate side while rupture happened in the nugget zone in all sort of connections . amancio-filho [11] studied the mechanical ,microstructure characteristic of disparate friction stir welds joints of aluminum alloys 2024-t351 and 6056-t4. this butt joints were made in diverse process parameters, mainly the rotational speed (500-1200rpm) and welding speed (150400mm/min), while axial force and tool geometry kept constant. on the basis of macro graphic analysis and micro hardness testing, the best found consequence was in the parameters range of rotational speed 800 rpm and welding speed 150 mm/min. khaira salman[12] rely on the shot peening method to improve the mechanical characteristic of joints which made using tungsten inert gas (tig) welding" and friction stir welding (fsw)" methods .tensile test samples were equipped from the connections metal and original alloy then exposed to shot peening method using steel ball of diameter 0, 9 mm and for 15 min. vickers hardness , microstructure were examination. results showed that a general decay in mechanical characteristic in tig and fsw welded joints comparing with base alloy while the fsw welded joint gives better mechanical characteristic than that of tig welded joint. this is due to the microstructure changes during the welding process .also it has been found that shot peening improved the mechanical characteristic of both welded joints due to the compressive residual stress generation in the weld zones. the present study the influence of pre shot peening ,welding speed, rotational speed on mechanical properties for dissimilar aluminum alloys 2024-t3and 6061-t6 friction stir welded joint. 2. experimental procedure 2.1. used alloys sheets of aluminum alloys aa6061-t6 and aa2024t3 are used to produce dissimilar friction stir welded joints. the results of the chemical analyses which is performed by arl spectrometer in the specialized institution of engineering industries are listed in table (1 and 2). kharia salman hassan al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 1928 (2018) 21 table 1, chemical analysis of the aa (6061t6) table 2, chemical analysis of the alloys aa (2024-t3) element al % ti% cr% zn% si% fe% mn% mg% cu% real value 92.6 0 0.05 0.1 o.4 0.3 0.6 1.5 4.4 the sheets were prepared into the required dimension (150mm×50 x6mm) by milling machine then some of its were exposed to shot peening process for producing severe plastic distortion on the specimen's surface by steel ball has diameters 1.25 mm for 15 minute from all sides by an air-blast machine tumbles control model (stb – ob) machine no. 03008 05 type., the nozzle askew angle is be removed by 10° with respect to the perpendicular axis. the distance from the nozzle to specimens place is about 120 mm, shot velocity was 40 m/ min. computerized (lab xrd-6000 shiatsu x-ray diffraction meter) was employed to measure the strain which result from shot peeing in the crystal lattice and the quantity of the strain was implemented in brag law to account the compressive residual stress in the shot peening material, the results of residual stress which obtained from device were recorded in table (3). the relation between 2 theta (deg) which represented the strain and psi (� in deg.) represented the specimen location and its incline with the axis was draw as shown in fig.1 (a and b). fig. 1. the relation between 2 theta (deg) and the specimen location for specimen ((a) 2024-t3and specimen (b) 6061-t6). also macro hardness was measured using vickers method and the results were recorded in table (3). table3, residual stress and vickers hardness for shot peening specimens. 2.2. categorization of specimens weld joints which equipped by friction stir method were compiled into party as listed in elements w% si fe cu mn mg cr zn al real value 0.6 0.4 0.3 0.12 1.0 0.2 0.18 rem. symbol vickers hardness kg/mm2 residual stress result (mpa) 2024-t3 152 -162.4 6061-t6 105 -143.543 kharia salman hassan al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 1928 (2018) 22 table 4, categorization of manufacture sample. 2.3. welding process the plates which equipped for friction stir welding joint from shot and without shot peening material were corroborated in location by mechanical fixeds. single pass welding process is used to make the butt weld connections. vertical semi-automatic milling machine was used for creation the butt welds joints. a welding tool made of high carbon steel. the tool dimensions is composed of shoulder of (20mm diameter) and probe of (6mm diameter and 5 mm length ).in this study the rotation speed tool (1400 rpm) was used to get many weld joints at mutable welding speed of (28,40,56 mm/min ) then fixed the welding speed for (40mm/min) and the same rotation speed (1400 rpm) to join the shot peening plate which is shown in fig(2 ) then for comparative the result with second parameter (rotational speed) the rotation speed was taken(1000)rpm at welding speed (40mm/min) to weld butt joint from shot and without shot plate .fig.(3,4,5)show the macrograph weld joint of specimen (a ,b,c) friction stir weld joint. fig. 2. pictures of butt friction stir welding for specimen (f ) at (40x). fig .3. macrostructure weld joint of specimen (a) friction stir weld joint at (40x). fig. 4. macrostructure weld joint of specimen (b) friction stir weld joint at (40x). symbol stat a friction stir welding for similar a2024-t3 at 1400 rpm and 40 mm/min b friction stir welding for similar aa6061 – t6 at 1400 rpm and 40 mm/min c friction stir welding for disparate at1400 rpm and 28mm/min d friction stir welding for disparate at 1400 rpm and 40 mm/min e friction stir welding for disparate at 1400 rpm and 56mm/min f pre shot+ friction stir welding for disparate at1400rpm and 40mm/min g friction stir welding for disparate at 1000 rpm and 40mm/min h pre shot+ friction stir welding for disparate at1000rpm and 40mm/min a r kharia salman hassan al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 1928 (2018) 23 fig. 5. macrostructure weld joint of specimen (c) disparate friction stir weld joint zones at (40x). the temperature during welding process is measured by resistance temperature detector (rtd which have excellent precision over a wide choice of temperature from200°c to 650°c. heat is created in friction stir welding method at the communication among revolving tool and plats that plasticizes the material in its. in present work the temperature is measured by placing a sensor at different points on the weld plat perpendicular to weld line and the results was shown fig.(6a) .the relation between time and temperature was clear in fig.(6b) fig. 6a. distribution of temperature on surface for specimens (c,d,e,f). fig. 6b. variation in temperature with time on the top surface. 2.4. microstructure test optical microscope is employed to inspect the micro structural for specimen ( c)in weld zone and specimen(g) in stir zone and for this purpose specimens were equipped including many pace such as grinding process by sic paper in diverse grits of (240,320,500, 600,800 and 1200). polishing is done by diamond paste has (0.3μm) with cloth. then specimens are washed by water and alcohol and desiccated using hot air etching for seem the structure by use keller’s reagent having of 95 ml distill water, 2.5 ml hno3, 1.5 ml hcl and 1 ml hf then washed after that were examined with me-600 computerized optical microscope supplier with a nikon camera, the tested result was shown in fig.( 7) and fig.(8). kharia salman hassan al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 1928 (2018) 24 haz nz at 1400 rpm nz at 1000 rpm fig. 7. microstructure of specimens (c) from 2024 –t3 side of the diverse areas for the welded disparate material at(40 x). fig. 8. microstructure of specimens (c) from 6061 –t6 side of the diverse areas for the welded disparate material at (40x) 2.5. micro hardness test the vickers micro hardness equipment with 200 gm load for 15 sec was used to measure the hardness for all disparate specimens weld joint on a cross section perpendicular to the welding line the result was shown in fig. (9) mg2si base haz tmaz nz tmaz nz nz base cual kharia salman hassan al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 1928 (2018) 25 fig. 9. micro hardness for specimens (a,b,c,d,e,g) 2.6. tensile stress mechanical characteristic like strength and ductility by tensile examination of the specimens such as the ultimate tensile stress (uts) yield strength (ys) and % elongation are determined. numerous samples for tensile examination are equipped from weld and un weld plate by measurements shows in fig.(10) agreeing to astm 176000 to test using testing machine smart series with preload value (n) 100 and cross head speed (mm/min) or rate. 20. extension the tested results are shown in table (5) and fig (11 a, b, c) fig. 10. dimension of tensile test specimenز fig. 11a. relationship between stress and strain for all specimens. kharia salman hassan al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 1928 (2018) 26 fig. 11. b.relationship between stress and strain for specimens(c,d,e). fig. 11. c.relationship between stress and strain for specimens (f, h). table 5, results of tensile properties and hardens for all specimens. symbol �� mpa ��mpa �� mpa e% hardness kg/mm2 a 270 268 200 7.0 105 b 197 180 170 7.5 84 c 262 157 175 9.5 90 d 200 153 165 4 87 e 191 101 110 9.5 85 f 225 155 210 9.5 97 g 92 66 75 6 85 h 90 60 90 2.8 90 3. discussion fig,(7) represented microstructure of weld zone to specimen (c) from the side of aa 2024t3 which contain elongated grains besides coarse dendritic structure with uniformly precipitates in very fine of (cu al) due to have the main element alloys is copper (cu)which is signed in table (2) that gives substantial increases in strength to allow precipitation hardening [13,14] also fig.(8 ) shows the microstructure in base metal from the side of aa 6061-t6 which contains coarse and elongated grains with regular repartition strengthening sediment of (mg2si.) due to existence of alloying elements such as silicon and magnesium. these two elements chain and undergo to sediment reaction and form strengthening sedimentation (mg2si) as shown by darkens particles.[13,14].but in stir zone (zn) for the same specimens seeing equated fine grain structure due to the material undergoes to deep plastic deformation at elevated temperature which it's become more fine when rotational speed is increased fig (7) at (1400 )r. p.m. hardness profile rely strongly on sedimentation conduct and a little on the grain size in the weld zones thus breakup and growth of the sediment would result in softening of joints in all specimens in table (4 ) and the hardness which measured in nugget was lower than the two base material aa2024-t3 and 6061-t6 in the same zone due to heat input and cold cooling . fig.(9 )and table(5) which show the received result of tensile examinations for all specimens in table ( 4) that seeing increases in the welding speed resulting in decrease of the tensile strength of all the fs welded joints fig(11b). this is due to deficient in a little contact period in the weld zone with deficient heat input fig. (6b) and reduced plastic inflow of the metal and reasons several void-similar faults in connections. the lowered of plasticity and rates of diffusion in the material causes a weak in interface. when welding speeds are higher connected with little heat inputs fig (9b), which effects in quicker cooling rates of the welded joint. this can meaningfully decrease the degree of the metallurgical changes happen through welding and the local strength of the individual regions across the weld zone[15,16]. from the other hand increasing in rotational speed contributed in increasing tensile strength fig.(11b) due to increasing in fractional heat input (9a,b).heat in put is effected on hard ness distributions which encounter more reduction when welding speed decrease and rotational kharia salman hassan al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 1928 (2018) 27 speed increase fig.(11c) terminally we see pre shot peening process contributed in improvement of mechanical properties due to comparison residual stress which be mentioned in fig (11c). 4. conclusion 1. welding process for similar weld joint material have little effect on mechanical properties compared with dissimilar weld joint material. 2. welding speed at 28 mm/min and1400r.p.m offer the best results for mechanical properties of the dissimilar weld joint 3. pre shoot contributed to improve 88% mechanical properties at increase welding speed to 40 mm/min and1400r.p.m for dissimilar weld joint compered without pre shot joint at the same weld conditions. 4. decreases in rotational welding speed cause decay in mechanical which proved at 98% when subjected to pre shot peening at rotational welding speed 1000r.p.m and 40 m/min welding speed. 5. reference [1] ahmed o.al-roubaiy” experimental and theoretical analysis of friction stir welding of al-cu joint “ int .j .adv. manuf. technol.(2014) 71: pp1631-1642 [2] s. jannet p.k. mathews r. raja “comparative investigation of friction stir welding and fusion welding of 6061-t6 and 5083-o aluminum alloy based on mechanical properties “journal achievements in materials and manufacturing engineering and microstructure volume 61 issue 2 ,2013 [3] m. song, r. kovacevic” thermal modeling of friction stir welding in a moving coordinate system and its validation “international journal of machine tools & manufacture vo.43 (2003)pp 605–615 [4] renju mohan “ finite element modeling for maximum temperature in friction stir welding of aa 1100 and optimization of process parameter by taguchi method “ijret: international journal of research in engineering and technology volume: 03 issue: 05 | may-2014, pp2319-1163 | [5] radisavljevic1”influence of fsw parameters on formation quality and mechanical properties of al 2024-t351 butt welded joints” trans. nonferrous met. soc. china 23(2013)pp 3525−3539 [6] h. s. pati “effect of weld parameter on mechanical and metallurgical properties of dissimilar joints aa6082–aa6061 in t6 condition produced by fsw” fractural ed integrity structural, 24 (2013)pp151-160; [7] nazar abdulwadood1, burak sahin1, nihat yildirim” effect of welding parameters on the mechanical properties of dissimilar aluminum alloys 2024-t3 to 6061-t6 joints produced by friction stir welding” niğde üniversitesi mühendislik bilimleri dergisi, cilt 3, sayı 1, (2014), pp. 25-36 [8] p. prasanna 1 ,“experimental and numerical evaluation of friction stir welds of a a6061t6 aluminum alloy “arpn journal of engineering and applied sciences vol. 5, no. 6, june 2010 pp 1-18 [9] saad ahmed khodir “microstructure and mechanical properties of friction stir welded dissimilar aluminum joints of aa2024-t3 and aa7075-t6 materials transactions, vol. 48, no. 7 (2007) the japan institute of metals pp. 1928 to 1937 [10] moreira p m g p, santos t, castro p m s t “mechanical and metallurgical characterization of friction stir welding joints of aa6061-t6 with aa6082-t6”, materials and design, vol .30, (2009), pp. 180-187. [11] amancio-filhoa s t, sheikhi s, “preliminary study on the microstructure and mechanical properties of dissimilar friction stir welds in aircraft aluminum alloys 2024-t351 and 6056-t4”, journal of materials processing technology, vol.206,2008 pp. 132–142. [12] khairia salman1 "effect of shot peening on the mechanical properties for welded joints of aluminum alloy 6061-t6" ndmrp 2015 [13] metals handbook, vol.2 properties and selection: nonferrous alloys and specialpurpose materials, asm international 10th ed. 1990. [14] ashwani kumar1 “friction stir welding of dissimilar materials/alloys”: int. j. mech. eng. & rob. res vol. 1 , no. 1, january 2014pp 106-112 [15] terry dickerson “ heat flow into friction stir welding tools” 4th international symposium on friction stir welding. park city, utah, usa, 14-16 may 2003 page 2 of 11 [16] aleksandar sedmak1” heat input effect of friction stir welding on aluminum alloy aa6061-t6 welded joint “thermal science, year 2016, vol.20, no.2, pp.637641. )2018( 19-28، صفحة1، العدد14دجلة الخوارزمي الهندسية المجلم خيرية سلمان حسن 28 لمجهرية والميكانيكية لوصالت لحام الخلط االحتكاكي لسبائك المنيوم متماثلة خواص البنية ا وغير متماثلة خيرية سلمان حسن بغداد -معهد التكنولجيا / قسم التقنيات الميكانيكية almaden20002000@yahoo.comالبريد االلكتروني: الخالصة حام انتجت تاثير القذف بالكرات الفوالذية السابق لعملية اللحام وكذلك سرعته الخطية والدورانية على الخواص الميكانيكية والمتالورجية لوصالت لان من الصفائح من اتحضير عدد .تم aa2024 t3–aa6061 متشابهة وذات المتانة العالية البطريقة الخلط االحتكاكي لسبائك االلمنيوم المتشابهة وغير بعدها عدة وصالت لحام دقيقة (15)ملم ولمدة (1.25)بابعاد ملم وان عدد من هذه السبائك تعرضت الى القذف بكرات فوالذية قطرها السبائك المختارة rpm(1400)مع تثبيت السرعة الدورانية عند mm/min(28,40,56)متماثلة والمتماثلة المقذوفة وغير المقذوفة وبسرعة لحام الانجزت من الصفائح غير في عملية لحام صفائح اللحام التي تم قذفها لبيان تاثير عملية القذف على rpm(1400) نفسها السرعة الدورانيةوب mm/min(40)وقد انتخبت سرعة لحام وتم قياس التغير في درجة الحرارة في مناطق اللحام باستخدام مزدوج حراري عمودية تمت عملية اللحام بواسطة ماكنة تفريز فقد الخواص الميكانيكيةاما وان افضل ومن النتائج التي تم الحصول عليها وجد انخفاض في الخواص الميكانيكة عند زيادة في السرعةوكذلك اجري اختبار الصالدة المايكروية والشد وان عملية القذف بالكرات الفوالذية قبل عملية اللحام ساهمت في تحسين الخواص الميكانيكية لدرجة (28m/min)هرت عند سرعة خطية مقدارها ظنتيجة .ةمقاربة لنتائج المعدن االساس وقد وجد تحسن في الخواص الميكانيكة عند زيادة السرعة الدوراني (microsoft word 42-49\307\346\321\345\307\344) al-khwarizmi engineering journal al-khwarizmi engineering journal,vol. 13, no. 1, p.p. 4249 (2017) experimental study to the effect of natural particles added to unsaturated polyester resin of a polymer matrix composite orhan s. abdullah department of mechanical engineering /university of technology. email: orhan_sabah@yahoo.com received 13 april 2015; accepted 4 august 2016)( s://doi.org/10.22153/kej.2017.08.004http abstract experimental investigations had been done in this study to demonstrate the effect of natural particles used as a reinforcement material to unsaturated polyester resin. the tensile test and water absorption were investigated according to (astm d638) and (astm d570), respectively. the influence of sunflower husk and pomegranate husk particles, used as a reinforcement material, on the tensile strength, young's modulus and water absorption with different weight fraction (3%, 7% and 10%) and particle grain size (50µm, 100 µm and 150 µm), has been investigated. the water absorption of polymer composites was studied by measuring the specimen weight before and after immersion in water for one hundred days. in the experiments of tensile test, all specimens loading was performed with (50kn) operating at a crosshead speed of 10 mm/min. it is observed that the addition of sunflower husk up to 10% and pomegranate husk particles up to 7% as reinforcement materials to polyester resin, leads to increase the tensile strength and young's modulus of the composite material prepared and the use of sunflower husk as a reinforcement material increased the tensile strength, young's modulus and water absorption were better than pomegranate husk at the same percentage of addition. the decrease in reinforcement material grain size led to increase the tensile strength, young's modulus and water absorption. therefore, all the best result seen in composites containing reinforcement material with (50µm). finally, the best result obtained in tensile strength, young's modulus and water absorption were with the addition of 10% sunflower husk as a reinforcement material to polyester resin. keywords: polyester, polymer composite; pomegranate husk, sunflower husk. 1. introduction from thousands years, human has tried to improve the available materials in their surroundings to preferable the life of the people around him and the community in overall. these attempts had led to different research over the years to find alternatives materials. a lot of studies had done on composite material to investigate this new material specially polymer matrix composite which be capable substitute in the different industrial applications, when compared to old used materials. also the studies show that the using of polymer composite gave a better performance than ceramics, polymeric materials or alloys [1]. there are two main type of polymer will used as matrix material, thermoplastic and thermoset. thermoplastic is able to reformed after solidification like nylon and polyethylene, while thermoset is a material when solidification cannot be reformed like epoxy and polyester [2]. the composite material is a result of two phases, the first one called the matrix, while the second called the reinforcements phase. the characteristic of composite materials is dependent on the characteristic of the two phase's common in the preparation of the composite material [2]. in recent years, many studies have been done for natural fillers like coconut shell, pomegranate core, pineapple leaf, ginger, palm kernel, etc. as fillers in order to substitute the conventional fillers by using the natural fillers as a orhan s. abdullah al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 4249(2017) 43 reinforcement material in polymer matrix composites to decrease the cost, rise productivity beside the enhancement of the mechanical properties[3]. in order to obtain the tensile strength and the young's modulus many researchers modified polymers using different natural fillers. n. w. a. razak and a. kalam [4] studied the effect of oil palm empty fruit bunch (opefb) on the mechanical properties and water absorption behaviour of opefb /ppnanoclay /pp hybrid composites. they observed that the increase of opefb fibre size has increased it flexural strength, modulus and water absorption at smaller opefb fibre size. moayad a. m. [5] study the effects of rice husk fillers on the mechanical properties of rubber composite and he discover that the increase in volume fraction of reinforcement materials leads to increase in young modulus and hardness. mohammed almamory et.al[6] studied the effects of shells powder on mechanical and physical properties of nature rubber, and they observed that the tensile strength and the hardness of the composite material will improved after the addition of reinforcement material. s. i. durowaye [7] studied the mechanical behaviour of coconut shell and palm fruit particulate polyester composites in order to develop an engineering material for industrial application. the results show the maximum strength that the coconut shell and palm fruit particulate polyester composites can withstand while being stretched or pulled before breaking, their weight % (reinforcement) must be kept below 10%. aseel basim et.al [8] studied the mechanical properties for polymer matrix composite material reinforced by nature filler, they used both high density polyethylene (hdpe), and low density polyethylene (ldpe) as matrix to the composite material and used coconut shell particles and fish shell particles as reinforced fillers. they observed that the addition of nature fillers improve the mechanical properties. aseel basim et.al[9] studied the effects of nature material (rice husk ash, carrot powder, and sawdust) as filler to fiber glass / epoxy composite on mechanical properties; they observed that the addition of fillers leads to incremental increase in water absorption, hardness, flexural strength and shear stress with increasing in volume fraction. jabbar h.[10] study the tensile and compressive properties of kaolin reinforced epoxy; he observed the tensile and yield strength of the composites decreases with rising kaolin content. it is also observed that mechanical properties increase with decrease in particle size in all cases. shaimaa h. kamel [11] study the effect of grapes and dates particles reinforced polyester matrix composite on some of the mechanical properties, the results showed that the tensile strength and the young's modulus of filled unsaturated polyester increase with the increment of the percentage of grapes and dates particles. also that the percentage of (3.5 %) represents the greatest value for the modulus of elasticity for unsaturated polyester reinforced with dates particle and the percentage of (5 %) represents the greatest value for the modulus of elasticity for unsaturated polyester reinforced with grapes particle. the aim of this research is to investigate the effect of adding pomegranate husk and sunflower husk in different grain size and weight fraction to polyester resin on tensile strength, young's modulus and water absorption. 2. experimental details 2.1 materials 2.1.1 matrix material unsaturated polyester used as a matrix material produced by (sir). it is in liquid state at room temperature but after adding the hardener will change to solid state. the hardener used to this purpose methyl ethyl keton peroxide with mixing ratio 1:50 hardener to polyester resin at room temperature. after the adding of hardener to the resin the process of mixing will start and keep for 10 minutes till the homogenous will completed [2]. 2.1.2 reinforcement material the particle were collected and crashed by using an electrical mill. the particulates were received by vibratory sieve shaker to get a suitable size of (150, 100, 50 µm). 2.2 specimens preparation hand layup technique was used in this research to prepare the specimens. glass mould used to casting the composite material specimens with dimension of (200, 150, and 5) mm as shown in figure (1) the inner face of the mould was covered with a layer of vaseline to ensure noadhesion between the polymeric material and the orhan s. abdullah al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 4249(2017) 44 mould. the specimens were prepared by mixing the unsaturated polyester with pomegranate husk and sunflower husk powder by using different grain size and weight fraction of (3%, 7%, and 10%) according to roll of mix in term weight fraction as shown in equations (1), (2) and (3). 0 0100×= c p p w w w …(1) 0 0100×= c m m w w w … (2) 1=+ mp ww … (3) where: wm, wp: the weight fraction of matrix material and particles respectively. wc, wm, wp: weight of composite material, matrix material and particles respectively. the particles were supplementary to polyester and hardener and then they were homogeneously mixed at room temperature inside the molud and then left 24 hours for solidification completed. 3. mechanical and physical tests 3.1 tensile test tensile test was used to study the effect of axial load applied to the specimen by using tensile testing machine (tensile test h50kt (tinius olsen)) england (uk) /mechanical engineering department /university of technology shown in figure (2). all the specimen have the same test conditions, the applied load was (50 kn), and the operating speed 10 mm/min. figure (3) shows some of the flat specimens was prepared to the purpose of tensile testing with different reinforcement particles grain size and weight fraction according to tensile test equations (4) & (5) and the american standard (astm d638) with thickness (5mm) as shown in figure (4). …(4) = …(5) σ: stress (pa), f: applied load (n), ao: original area (mm 2 ), �: strain (unit less), ∆l: length change (mm), lf: final length (mm), lo: original length (mm). 3.2. young's modulus the young's modulus can be obtained by calculating the slope of the stressstrain curve for the tensile test in the proportional limit zone [12]. …(6) where: e: young's modulus (pa), σ: stress (pa), �: strain (unit less). 3.3 water absorption disc specimens were prepared with diameter of 40 mm and thickness 5mm in order to obtain the water absorption of the composite material. the specimens weighted before and after immersion in water according to astm d 570 standard as shown in figure (5). the increase in the weight of the specimens was calculated by using equation (7). water absorption ..(7) the specimens were immersion for one hundred days in water and it was weighted every ten days. fig. 1. the moulds shape. orhan s. abdullah al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 4249(2017) 45 fig . 2. tensile test machine. fig . 3. tensile test specimens. fig. 4. tensile test standard fig. 5. water absorption specimen. 4. result and discussion 4.1 tensile test from figure (6), it can observe that the addition of sunflower husk particles as a reinforcement materials leads to increase the tensile strength with the increasing in weight fraction of the reinforcement material by (11.6%, 31.5%, and 46.6%) respectively with particle grain size (50 µm) due to the high linkage between polyester and sunflower husk particles which leads to increase the resistance against the applied axial load. also from the same figure it can recognize that the decrease in particles grain size leads to raising the tensile strength, because of that the decreasing in particles size leads to more contact between the matrix material and sunflower husk particles. fig. 6. effect of sunflower husk particles on tensile strength. figure (7) shows the stressstrain curves of pure polyester and (3%,7% and 10%) sunflower husk (sh) weight fraction respectively with (50µm) grain size. orhan s. abdullah al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 4249(2017) 46 fig. 7. stress-strain curves of different weight fraction of sunflower husk. while figure (8) show the effects of pomegranate husk particles on tensile strength with different particle grain size and weight fraction, from this figure it can see that the addition of particles leads to increasing in tensile strength due to increasing of pomegranate husk percentage till 7% after this percent the tensile strength will be decreases with all particle grain size, a similar behavior was seen by s. i. durowaye et.al[7] we use coconut shell and palm fruit particles as a reinforcement material to polyester resin this may be due to increase in discontinuity between the particles surface and the matrix as the reinforcement concentration increases in the two composites. fig. 8. effect of pomegranate husk particles on tensile strength. 4.2 young's modulus the relationship between the young's modulus and sunflower husk particles percentage was shown in figure (9). it can notice that the increasing in young's modulus causing be the addition of reinforcement particles which added to unsaturated polyester resin. sunflower husk particles work to prevent the polyester chains from slipping and this leads to increase the young's modulus. the addition of 10 % sunflower husk particles with grain size (50 µm) gives the highest young's modulus with increasing by 27.2% better than unsaturated polyester resin specimen. analogous demeanor was seen by shaimaa h. kamel [11] with the addition of grapes particles to unsaturated polyester up to 5% these quantities of grapes particles strengthen the polyester specimen and increase the young's modulus. fig. 9. effect of sunflower husk particles on young's modulus. figure (10) appears the behavior of young's modulus after adding pomegranate husk particles with different weight fraction and particles grain size to unsaturated polyester resin. it can be observed that the addition of pomegranate husk particles with any particle size was used increase the young's modulus up to 7% percent, while after this percent the young's modulus values starting decrease. fig. 10. effect of pomegranate husk particles on young's modulus. orhan s. abdullah al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 4249(2017) 47 4.3. water absorption water absorption behaviors of the composite in water immersion against the time in (days) are shown in figures (11) and (12). the addition of sunflower husk and pomegranate husk particles leads to increase the water absorption with the increasing in immersion time. a similar behavior was seen by and n. w. a. razak and a. kalam [4] aseel basim et.al [8] with the addition of natural fiber or particles the water absorption increase with the increasing in immersion time which leads to increase the humidity and decrease the adhesion between the matrix material and the reinforcement material made the composite material may be containing voids and porosity. fig. 11. effect of sunflower husk particles on water absorption. fig. 12. effect of pomegranate husk particles on water absorption. figure (13) show the difference in water absorption values at using varies particles grain size as a reinforcement material. the results show that the decrease in particle grain size leads to increase the water absorption and the use of sunflower husk have water absorption high than pomegranate husk. in the same filled alaa a.mohammed [13] and hussein .a.ali [14] have similar result where using different particles grain size the lowest particle size have the highest water absorption due to the decrease in contact area with the matrix. fig. 13. effect of sunflower husk and pomegranate husk grain size particles on water absorption. *all abbreviations and symbols shown in table (1) 5. conclusions from the up results it can conclude the following: 1the addition of sunflower husk up to 10% and pomegranate husk particles up to 7% as reinforcement materials to polyester resin leads to increase the tensile strength and young's modulus of the composite material prepared. 2using of sunflower husk as a reinforcement material increase the tensile strength and young's modulus better than pomegranate husk at the same percentage of addition. 3the water absorption of composite material prepared in this research increase with the increasing of reinforcement material weight fraction. 4the addition of 10% sunflower husk as a reinforcement material to polyester resin give the best result in tensile strength and young's modulus, where the tensile strength and young's modulus increasing by (46.6%,27.2%) respectively. 5the decreasing in reinforcement material grain size leads to increase the tensile strength, young's modulus and water absorption. there for all the best result seen in composites containing reinforcement material with (50µm). orhan s. abdullah al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 4249(2017) 48 table 1, list of abbreviations and symbols 6 abbreviations and symbols meaning units hdpe high density polyethylene ldpe low density polyethylene opefb oil palm empty fruit bunch astm american society of testing and materials sh sunflower husk p pomegranate sir saudi industrial resins 6. references [1] sabu thomas, kuruvilla joseph, sant kumar malhotra, koichi goda, and meyyarappallil sadasivan sreekala," polymer composites", volume 1, first edition, published by wileyvch verlag gmbh & co. kgaa, 2012. [2] g.piatti, "advanced in composite materials", applied science publishers ltd., london, 1987. [3] w. bolten, "engineering materials technology", third edition, a member of reed elsevier group, 1998. [4] n. w. a. razak, and a. kalam, " effect of opefb size on the mechanical properties and water absorption behaviour of opefb/ppnanoclay/pp hybrid composites", procedia engineering, vol.41, p.p1593 – 1599, 2012. [5] moayad a. m., "effects of rice husk filler on the mechanical and rheogical properties of rubber component based on natural rubber", the iraqi journal for mechanical and material engineering, vol.13, no.2, 2013. [6] mohammed almamory et.al, "effect of shells powder on physical properties of natural rubber", the iraqi journal for mechanical and material engineering, vol.13, no.2, 2013. [7] s. i. durowaye1,*, g. i. lawal, m. a. akande1, v. o. durowaye, "mechanical properties of particulate coconut shell and palm fruit polyester", international journal of materials engineering 2014, 4(4): 141-147 composites. [8] aseel basim abdul-hussein, emad saadi al-hassani, and reem alaa mohammed, "effect of nature materials powders on mechanical and physical properties of glass fiber / epoxy composite", engineering and technology journal, vol.33, part (a), no.1, 2015. [9] aseel basim abdul-hussein, emad saadi al-hassani, and reem alaa mohammed, "influence of coating with some natural based materials on the erosion wear behavior of glass fiber reinforced epoxy resin", al-khwarizmi engineering journal, vol.11, no.2, 2015. [10] jabbar h. mohmmed, "tensile and compressive properties of kaolin reinforced epoxy", al-khwarizmi engineering journal, vol.11, no.3, 2015. [11] shaimaa h. kamel, "studing some of the mechanical properties of unsaturated polyester reinforced by re-cycled natural materials", al-qadisiyah journal for engineering sciences, vol. 8, no. 2, 2015. [12] ferdinand l.singer and andrew pytel, "strength of materials", third edition, harper &row publishers, new york, 1980. [13] alaa a. mohammed, "study the thermal properties and water absorption of composite material reinforced with data and olive seeds", the iraqi journal for mechanical and material engineering, vol.15, no2, 2015. [14] hussein, a. ali. , salim, r. d. & sultan, a. ali, "water absorption and mechanical properties of high-density polyethylene/egg shell composite", journal of basrah researches (sciences), vol. (37), no. 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accepted 12 may 2016) http://dx.doi.org/10.22153/kej.2016.05.005 forming is a modern technique of sheet metal forming in which a uniform sheet is the progressive action of a forming tool. the tool movement is governed by a cnc y this way the sheet with pure deformation stretching. in spif process, the predict models for estimate the product quality. using simulated annealing algorithm in spif has been modeled. in the development of this predictive model step depth have been considered as model parameters. maximum peak height (rz) and parameter to assess the surface roughness of incremental forming the data required has been generate, compare and evaluate to simulated annealing algorithm (saa) is utilized to develop an effective mathematical model to predict optimum (sa), an exponential cooling schedule depending on newtonian cooling process is by choosing the number of iterations at each step on the experimental work is done. the sa predict the forming parameters (speed, feed and step size) on surface quality in forming process of al 1050 based on (anova) analysis of variance were used to find the simulated annealing algorithm (saa), single point incremental forming (spif), forming parameters, incremental forming is a flexible sheet metal forming process which uses simple generic and cheaply made tools to locally deform a sheet of metal along a predefined tool path without using cnc milling machine, this very simple. tool diameter, , friction, feed rate, are some of the important that effect on the product accuracy using this method [1]. less geometrical accuracy and m processing time with respect to processes are some of process; so many researchers this problem by using different types of analysis methods to predict and optimized the best process parameters that give good surface accuracy schematic diagram of single point forming (isf) illustrated in fig al-khwarizmi engineering journal (2016) optimization and prediction of process parameters in spif that affecting on surface quality using simulated department of production engineering and metallurgy / university of technology sheet metal forming in which a uniform sheet is locally movement is governed by a cnc milling machine. in spif process, the research is using simulated annealing algorithm this predictive model, spindle speed, feed rate maximum peak height (rz) and arithmetic mean surface incremental forming parts along and to the proposed models that simulated annealing algorithm (saa) is utilized to develop an effective mathematical model to predict optimum nian cooling process is used is done. the sa algorithm is used to in forming process of al 1050 based on the best factors that effect on ng (spif), forming parameters, accuracy using this method of forming process less geometrical accuracy and more time with respect to conventional processes are some of the limitations of this researchers attempted to solve this problem by using different types of analysis optimized the best process parameters that give good surface accuracy [2]. a single point incremental in figure (1). [3] aqeel sabree baden al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 8192(2016) 82 fig. 1. principle of the single point incremental forming process [3]. 2. literature review a series of experiment have been carried out in design of experiments to investigate the effect of forming parameters such as spindle speed, feed rate and step size on surface roughness using vertical cnc milling machine. r. varthini and et al [4], use a three-layer back propagation neural network (bpnn) and genetic algorithm (ga), a second order mathematical prediction model was established in this paper to predict and optimize both the wall angle and surface roughness for the material al-1050 alloy sheets in relation with five common spif forming parameters: vertical step size, lubrication, spindle speed, tool diameter and feed rate. o.u. lasunon [5], illustrated the effect of process parameters on the mean surface roughness (ra) of aluminum alloy product by a single-point forming process. three present parameters are forming depth (0.015 and 0.030 in), feed rate (12.5, 25 and 50 in/min), and wall angle (45° and 60°). m. vahdati and et al [6], present optimization and a statistical analysis of factors that effected on this varibles are used the uva spif process. at this work, the experiment design technique using response surface methodology (rsm). the specified input variables of the process used as the controllable factors, like sheet thickness, vertical step size, wall inclination angle, tool diameter and feed rate are. the results obtained from the regression analysis and analysis of variance (anova) of the experimental data confirms the accuracy of the mathematical model. the literature review illustrated in table (1). table 1, literature review presents the optimization approach in spif process. no. authors optimization approach 1 s. kurra and et al (2012)[2] artificial neural networks and genetic algorithm 2 h. s. beravala and et al (2015)[3] feasibility study 3 v.mugendiran and et al (2014)[7] response surface methodology 4 b. s. raju and et al (2014)[8] taguchi method, anova 5 s.p.shanmuganatan and et al (2014)[9] response surface methodology 6 er. alamdeep c. and et al (2015)[10] taguchi method and artificial neural networks 7 j. r. patel and et al (2015)[11] grey relational analysis 8 p.b.uttarwar and et al (2015)[12] taguchi method 9 j. r. patel and et al (2015)[13] anova 3. experimental work 3.1. material and process samples of (al 1050) aluminum metal sheets, 225 x 225 x 0.9 mm, were used to perform the experiments (9-samples). the geometry of part is shown in figure (2). the experimental work was applied using oil lubricant on a c-tek three-axis (km-80d), cnc milling machine equipped with a maximum rotational speed of 6000 rpm, feed rate of 10 m/min. cnc part programs for tool path was created. the experimental work of the workpiece for hem-spherical tool is illustrated in figure (3). the chemical composition and mechanical properties of this aluminum (al 1050) is illustrated in tables (2 & 3). for forming operation the tool used for performing is tool steel (12mm diameter). using a surf test (mahr pocket surf test) measuring instrument, the forming surface was measured after cut off the samples to simplest the measurement procedures at three different positions with the cutoff length 2 mm and maximum peak to valley height (rz) and arithmetic mean surface roughness (ra) are used as output parameters to evaluate the surface quality of incremental forming product along and aqeel sabree baden al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 8192(2016) 83 across tool path direction and values are recorded in microns that illustrated in figure (4). fig. 2. geometry of part and part program. fig. 3. the experimental setup and nine-samples fig. 4. surface roughness measurement device table 2, chemical composition of al 1050 alloy (wt %).“ elements al cr cu fe mg mn si ni zn percentage % 99.5 0.001 0.013 0.315 0.001 0.013 0.142 0.003 0.006 aqeel sabree baden al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 8192(2016) 84 table 3, mechanical properties of al 1050 alloy..“ yield point (mpa) ultimate strength (mpa) hardness (hbr) elongation (%) 65-78 80-100 20-30 35-42 3.2. plan of experiments the powerful tool for improving productivity is taguchi method has become during research and development in recent years so at low cost that can be produced good quality parts quickly. uses a special design of orthogonal arrays with a small number of experiments taguchi method to study the entire parameter space. the methodology of taguchi for three factors at three levels is used for the applied of experiments. to define the nine trial conditions, is used the degrees of freedom required for the study is six and taguchi’s (l9) orthogonal array. the levels and process parameters are illustrated in table (4). the average response and replicated twice values for each of the nine trials or process designs are used for this work. table (5) illustrated the present work and the test results, and figures (5, 6 and7) present the relationship between experimental data. table 4, process parameters and their levels..“ parameters unit level 1 level 2 level 3 rotational speed (s) rev/min 0 400 800 feed rate (f) mm/min 400 700 1000 forming depth (d) mm 0.3 0.6 0.9 table 5, experimental layout using an l9 orthogonal array and corresponding results.“ process parameters average response exp. no. spindle speed rev/min feed rate mm/min depth size mm time min surface roughness µm ra-across rm-across ra-along rm-along 1 1 1 1 77.7 0.63 4.8 0.30 2.1 2 1 2 2 22.4 1.05 5.4 0.33 2.1 3 1 3 3 10.6 2.33 9.3 0.38 2.7 4 2 1 2 39.3 1.08 4.7 0.72 4.1 5 2 2 3 15.1 1.02 5.9 1.33 6.9 6 2 3 1 31.1 0.95 5.4 1.10 5.9 7 3 1 3 26.4 0.93 7.5 0.54 2.6 8 3 2 1 44.4 1.01 3.6 0.98 5.9 9 3 3 2 15.7 0.9 5.9 1.49 3.8 fig. 5. the relationship of mean roughness (across) with respect to process variables. aqeel sabree baden al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 8192(2016) 85 fig. 6. the relationship of maximum roughness (across) with respect to process variables. fig. 7. the relationship of roughness (along) with respect to process variables. 4. optimization of machining parameters. 4.1. structure of simulated annealing algorithm. the steps of the present work (simulated annealing algorithm (saa)) are shown in figure (8). using simulated annealing algorithms (saa) to optimize the present work, the limited optimization problem is stated as follows: from the given data for surface quality, using fitness value the response function can be found as: aqeel sabree baden al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 8192(2016) 86 minimize, time=162.544-0.099*f228.278*d+93.519*d2+0.086*f*d ...(1) ra-across=1.979+0.002*s-0.006*f+1.006*d0.005*s*d+1.5d2+4.33*10-6*f2 …(2) rm-across=10.503-0.001*s-0.019*f-4.417*d0.001*s*d-0.001*f*d +1.486*10-5*f2 +8.333*d2 …(3) ra-along=0.062+0.002*s+0.003f-2.293*d 3.104*10-6*s2-2.481*10-6*f2 +1.25*10-6*s*f +0.002*s*d+0.003*f*d …(4) rm-along=-1.993+0.014*s+0.024*f-14.5*d 1.521*10-5*s2-1.593*10-5 *f2+11.296*d2 ...(5) fig. 8. simulated annealing flowchart. subject to 0 rev/min ≤ v ≤ 800 rev/min 400 mm/min ≤ f ≤ 1000 mm/min 0.3 mm ≤ d ≤ 0.9 mm xiu ≤ xi ≤ xil where xiu and xil are the upper and lower bounds of process parameters xi . x1, x2, x3 are the spindle speed, feed rate and forming depth respectively. the following parameters have been selected to obtain optimal solutions with less computational effort to optimize the related work using saa. initial temperature ti= 1 co maximum no. of iterations = 5709 4.2. performance evaluation of simulation analysis the sa algorithm was applied using matlab r2014b. the input forming variables were input to the simulated program. table (6) presents the input parameters and the minimum values of surface roughness. in order to get the minimum surface roughness, it is possible to find the variables at which the spif process can be used. figures (9, 11, 13 and 15) shows the applying of saa and figure (10, 12, 14 and16) shows performance of saa. from the optimization results of the sa program it can be concluded that it is possible to select a combination of spindle speed, feed and forming depth to achieve the better surface finish. aqeel sabree baden al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 8192(2016) 87 table 6, the input parameters with respect to output values of simulated annealing algorithms. “ forming parameters simulated annealing algorithm ra-across rm-across ra-along rm-along rotational speed ,s (rev/min) 2.743 796.671 201.065 0.024 feed, f(mm/min) 696.318 637.803 401.55 400.343 depth of forming, d (mm) 0.3 0.303 0.899 0.636 min. surface roughness, (microns) 0.3387 2.6253 0.1762 0.4096 fig. 9. applying of simulated annealing algorithm (ra-across). fig. 10. performance of simulated annealing algorithm (ra-across) aqeel sabree baden al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 8192(2016) 88 fig. 11. applying of simulated annealing algorithm (rm-across). fig.12. performance of simulated annealing algorithm (rm-across) aqeel sabree baden al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 8192(2016) 89 fig. 13. applying of simulated annealing algorithm (ra-along). fig. 14. performance of simulated annealing algorithm (ra-along). aqeel sabree baden al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 8192(2016) 90 fig. 15. applying of simulated annealing algorithm (rm-along). fig. 16. performance of simulated annealing algorithm (rm-along). 5. conclusion 1. in incremental forming process, the process parameters (speed, feed and step size) is the main factors that effect on surface quality. 2. rotational speed in incremental forming process have a little effect on process time and may be neglected in this study, while feed rate and step size have the main effect on process time (99%). 3. the results of simulated annealing algorithm and the effectiveness experiments confirm that the developed empirical models for the output responses provide the predicted values and shows an excellent fit of these response factors that are close to the experimental values , at (92-98.8)% confidence level. but out of the optimization range, the predicted was decrease to 82% especially at high range of feed and aqeel sabree baden al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 8192(2016) 91 forming depth due to forming force and vibration due to high force. 4. surface roughness has been test across the direction of tool path take the main effect on surface quality and the surface roughness along the tool path direction have a little effect but must be taken. 5. low rotational speed gave the best surface quality, because decrease the average across roughness, the effectiveness range up to (70%). 6. high feed rate take the best surface quality up to (28%) in both directions of testing. 7. decrease in step size gave the best surface quality up to (51%), in another wise increase in process time. 6. references [1] s. c. babu and v. s. senthil kumar, effect of process variables during incremental forming of deep drawing steel sheets, european journal of scientific research, vol.80, no.1, pp.50-56, 2012. [2] s. kurra, n. h. rahman, s. p. regalla and a. k. gupta, modeling and optimization of surface roughness in single point incremental forming process, journal of materials research and technology, vol.4, no.3, pp.304–313, 2015. [3] h. s. beravala, j. r patel, h. p. prajapati and r. s. barot, setup development and feasibility check of single point incremental forming (spif) process on vmc for al19000 alloy, international journal of engineering trends and technology, vol. 20 no. 4, 2015. [4] r. varthini, r. gandhinathan, c. pandivelan and a. jeevanantham, modeling and optimization of process parameters of the single point incremental forming of aluminum 5052 alloy sheet using genetic algorithm-back propagation neural network, international journal of mechanical and production engineering, vol. 2, issue 5, 2014. [5] o. u. lasunon, surface roughness in incremental sheet metal forming of aa5052, advanced materials research vols. 753-755, pp. 203-206, 2013. 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[9] s.p.shanmuganatan and v.s.senthil kumar, modeling of incremental forming process parameters of al 3003 (o) by response surface methodology, 12th global congress on manufacturing and management, gcmm 2014. [10] er a. cheema, er. r. kumar, optimizing and predicting surface roughness on milling machine by using taguchi & ann on d2 steel, international journal in it and engineering, vol.03 issue-05, 2015. [11] j. r. patel, k. s. samvatsar, h. p. prajapati and s. s. rangrej, optimization of process parameters for reducing surface roughness produced during single point incremental forming process, international journal on recent technologies in mechanical and electrical engineering, vol. 2 issue 9, 2015. [12] p.b.uttarwar, s.k.raini and d.s.malwad, optimization of process parameter on surface roughness (ra) and wall thickness on spif using taguchi method, international research journal of engineering and technology, vol. 02 issue 09, 2015. [13] j. r. patel, k. s. samvatsar, h. p. prajapati and u. m. sharma, analysis of variance for surface roughness produced during single point incremental forming process, international journal of new technologies in science and engineering, vol. 2, issue. 3, 2015. ���ي ��ن �� )2016( 81-92، � �� 4، ا���د����12 ا���ارز � ا����� � ا���� 92 � وا�'���ء ��', �ات ��� � ا�'*( ا���)� ا�'� &%$� ��# "�دة �/ ا�5)4 ا��2&3 ��2'��ام ا0 �282ة ا�'��67 � �9ارز ���ي ��ن�� ��ج وا����دن �� ا�,�+�� ا��*"(�()'� /&%$ ھ"! � ا 70061@uotechnology.edu.iq -��.و*��:ا�0./! ا ا��ـ;�ــ� ا��h"'�ت ا�?!/g� fت6*'5 ا�bc�de ا���!�'� ا��ت�$ 28 ط./@ 7%7� +2 ا�?.<�ت ا�!ورا�'� ا��ت;د/:� 8!ة ا��6*'5 7�8'� ا��6*'5 ا��4ا/!ي +2 !ت� 5%7%�+ 5*6iة و!jت6*'5 وا �kh� -f .$��'� +st 2ل 7�8'� آe(رة o:iه ا���7'� اpداة ت6*5 ا�j .i bc�de.<� ھoه ا��!ة +2 &50 +�<"� ا��m6'5 ا��l+.0 وت -h"ا� u?%ا�. -kh"6*'5 ا����(ذج ��"0(ء )(دة ا�%bk ا�"�تl +2 7�8'� ا� ./)kت x78 4'>.���i م)h/ z?0ا ا�o0(ء . ھ"�ت�$ 7�8'� ا��k(/. ا�?�]7� �"�(ذج ا� �\!ام +�m'.ات ا���7'� �i)دوران �و�8@ ا�"4ول، .8 �/om�8��0ر ) +�!ل ا���( _ ا�\6(�� . 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(microsoft word 129-137\323\315\321 \343\345\317\355) al-khwarizmi engineering journal,vol. 13, no. 1, p.p. big-data management using map department of computer email: (received 29 https://doi.org/10.22153/kej.2017.11.004 abstract database is characterized as an arrangement of data that is sorted out and disseminated in a way that allows the client to get to the data being put away in a simple and more helpful way methods of data analytics may not be able to manage and process the large amount of data. in order to develop an efficient way of handling big-data, this work studies t the cloud. this approach was evaluated using hadoop server and applied on eeg big proposed approach showed clear enhancement reduction on response time. the obtained results provide eeg researchers and specialist with an easy and fast method of handling the eeg big data. keywords: big-data, cloud computing, electroencephalogram 1. introduction database is characterized as an arrangement of data that is sorted out and disseminated in a way that allows the client to get to the data away in a simple and more advantageous way. by utilizing this strategy, the client will be permitted to direct any sort of adjustments over a specific arrangement of data. there are diverse sorts of databases that are right now being utilized by kind of data that should be put away. among one the most generally utilized databases that is being utilized to get to element data is the value database [1]. the utilization of this database to recover dynamic data, for example, stock data, has been extraordinarily examined as of late. the other typical kind of database is known as illustrative database [2], which is used for social event and organizing static data, for instance, legitimate results or land comes about that don't much of the time change on a steady base. khwarizmi engineering journal,vol. 13, no. 1, p.p. 129137 (2017) ement using map reduce on cloud: case study, eeg images' data sahar mahdie klim department of computer engineering / college of engineering / misan university email: sahar_mahdi@uomisan.edu.iq 29 march 2016; accepted 7 november 2016) https://doi.org/10.22153/kej.2017.11.004 database is characterized as an arrangement of data that is sorted out and disseminated in a way that allows the away in a simple and more helpful way. however, in the era of big methods of data analytics may not be able to manage and process the large amount of data. in order to develop an data, this work studies the use of map-reduce technique to handle big the cloud. this approach was evaluated using hadoop server and applied on eeg big-data as a case study. the proposed approach showed clear enhancement for managing and processing the eeg big-data with average of 50% reduction on response time. the obtained results provide eeg researchers and specialist with an easy and fast method electroencephalogram, mapreduce, hadoop,. database is characterized as an arrangement of that is sorted out and disseminated in a way data being put away in a simple and more advantageous way. by utilizing this strategy, the client will be permitted to direct any sort of adjustments over a specific . there are diverse sorts of databases that are right now being utilized by kind that should be put away. among one the most generally utilized databases that is being is the value-based utilization of this database to recover dynamic data, for example, stock data, has been extraordinarily examined as of late. the other typical kind of database is known as illustrative database [2], which is used for social a, for instance, legitimate results or land comes about that don't much of the time change on a steady base. the utilization of a database takes into account arranging a huge substance of data that are recovered from different assets in an expansive data framework known as data warehousing this framework is actualized for a simple recovery of inquiry and investigating forms in a productive way, rather than getting to exchange forms. the data put away in the warehousing framework comprises of authentic for the most part recovered from verifiable other than different sources as well. this framework works by isolating examination workload from exchange workload, with the goal that this would take into consideration arranging the data different assets effectively. what's more, this framework capacities by enrolling extraction, transportation, transforming and loading (etl) arrangement [4]. moreover, other application procedures, for example, online diagnostic procedures and customer examination apparatuses take into consideration gathering the al-khwarizmi engineering journal case study, eeg misan university database is characterized as an arrangement of data that is sorted out and disseminated in a way that allows the . however, in the era of big-data the traditional methods of data analytics may not be able to manage and process the large amount of data. in order to develop an reduce technique to handle big-data distributed on data as a case study. the data with average of 50% reduction on response time. the obtained results provide eeg researchers and specialist with an easy and fast method the utilization of a database takes into account arranging a huge substance of data that are recovered from different assets in an expansive ramework known as data warehousing [3]. this framework is actualized for a simple recovery of inquiry and investigating forms in a productive way, rather than getting to exchange put away in the warehousing framework comprises of authentic data, which are for the most part recovered from verifiable data, other than different sources as well. this framework works by isolating examination workload from exchange workload, with the goal that this would take into data selected from different assets effectively. what's more, this framework capacities by enrolling data through extraction, transportation, transforming and loading (etl) arrangement [4]. moreover, other application procedures, for example, online procedures and customer examination apparatuses take into consideration gathering the sahar mahdie klim al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 129137 (2017) 130 data and sending the accumulated data effortlessly to the business clients in a proficient way. subsequently, the usage of data warehousing has hoisted the calculation inside the business sector and which to be sure has been created further by the execution of systems administration framework. this has added to updating the execution of an incredible measure of data in an auspicious productive way. the primary reason for data warehousing framework is to make a long haul stockpiling framework so as to be utilized by the individuals who require getting documented data for future reference [5]. in spite of the way that the foundation of databases takes into account a proficient and simple system of recovering data adequately, conventional databases have their own particular shortcoming focuses [6]. for instance, standard database and programming techniques were not prepared for being used to handle, mastermind and have control over an extensive volume of data, for instance, sorted out, semi-composed or unstructured data [7]. this opening prompts the headway of a wonder known as big data [8]. this term is utilized to delineate enormous dataset comprising of 4-v definitions: “volume”, velocity”, “variety” and “value”, (for example, electronic” restorative records, electrocardiogram” and biometrics information) [9]. in any case, these datasets were appeared to force an issue with capacity, representation and investigation [9]. consequently, keeping in mind the end goal to settle this issue, new programming frameworks have been made to experience the issues connected with these datasets. the recently created programming frameworks are manufactured especially to arrive parallelism from huge accumulations of processing groups, instead of acquiring them from super pc. these figuring bunches comprise of ordinary procedures, it can connected to ethernet connections or some other unobtrusive switches. these redesigned programming structures are frequently called “distributed file system” (dfs) [10]. this framework presents bigger joins than the circle squares that is found in customary working frameworks. what's more, dfs gives an additional element of data replication to ensure against data disappointment, which for the most part happens because of the expansive dataset being entered. subsequently, this has risen the need to develop the utilization of map reduce keeping in mind the end goal to precisely prepare big-data and concentrate the potential prescriptive and prescient big-data [11] [12]. investigative is generally used to represent diverse purposes and strategies used to direct different procedure in a dataset. there are three sorts of examination. [11]: a) “descriptive” investigation: a method that is utilized to subtract the dataset of premium and make typical reports that can be utilized to respond inquiries, for example, "what was the deal? what is the issue? what activities are required? ". b) “predictive” investigation: as a reason for future data being given by illustrative systematic methodology, a prescient logical methodology has been created. this methodology utilizes the need of utilizing measurable models of the chronicled datasets with a specific end goal to figure more data about what's to come. prescient logical methodology is a valuable methodology of noting inquiries like "why is this event? what will happen next?" this sort of prescient methodology depends on the how shut the data acquired as contrasted and other factual models. c) prescriptive investigation: this kind of expository methodology includes the utilization of different data model, for example, multi variables incitement and recognizing the connection between different variables. this methodology is proficient for noting certain inquiries, for example, "what could happen if a specific situation is utilized? what is the most fitting situation to be actualized? " elite registering approach [13] is a technique for organizing parallel pathways for running anomalous state application programs in a compelling, more tried and true and less repetitive way. this strategy applies for structures that work at a skimming motivation behind 1012 consistently. prevalent enrolling is utilized for handling convoluted issues and reasonably fulfilling research practices using bleeding edge pc workplaces, affectation and by executing distinctive preparing resources. the distinctions among lattice processing and disseminated registering frameworks are as per the following [14]: a) a disseminated figuring framework can deal with hundreds or a large number of pc framework, which are described of having a constrained access of preparing assets, for example, cpu, memory and capacity. then again, the lattice processing framework concentrates more on the proficiency of coordinating heterogeneous frameworks with administration servers, stockpiling, ideal workload and system. sahar mahdie klim al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 129137 (2017) 131 b) a matrix registering framework is all the more particularly intended to improve calculation inside different authoritative spaces, which to a great degree varies from the customary conveyed figuring framework. for the greater part of figuring frameworks, a solitary processor is generally utilized alongside its principle memory, store and nearby plate. beforehand, applications that called for parallel pcs with numerous processors and certain equipment projects were utilized. be that as it may, the interest of utilizing extensive scale web administrations required the interest of all the more registering being done in light of establishment. what's more, registering hubs were appeared to significantly diminish the expense when contrasted with exceptional reason parallel machine. along these lines, recently created registering offices have added to the improvement of more upgraded programming structures. the upside of using such structures is that it keeps the unwavering quality issues that may emerge when figuring equipment framework is made out of a great many free sections that could neglect to work appropriately [14]. moreover, these systems can likewise handle parallelism, which may happen accidently. the group creates errands that can be observed by the expert hub, which is usually known as the namenode [15], and it is accountable for piecing the data, duplicating it, bringing in the data to the circulated processing hubs, checking the status of the bunch and gathering/assembling the outcomes gained. notwithstanding the advancement of dfs, other abnormal state programming has been composed. the most famous structure created is the mapreduce system. mapreduce is a typical programming system that is used for data serious application that are displayed by google [16]. mapreduce assembles thoughts from different useful programming frameworks the especially characterizes map and reduce assignments so as to run colossal arrangements of appropriated data all the more proficiently. the usage of mapreduce permits a wide range of figurings on the expansive scale to be done on registering groups all the more viably and in a more capable manner that could diminish equipment disappointments amid the calculation procedure [17]. in this manner, the hadoop made simpler to process substantial measure of data sequentially where it could read the entire envelope each one in turn [18]. while, in ordinary programming every document is perused and dissected independently. this will therefor takes time that longer and requires greater memory and limit. the “hadoop” moreover saved attempt that is required in obtaining the code, as run of the mill programming requires to perform programming on the records. on the other hand the aide code is speedier and can be consolidated successfully. 1.1. problem declaration as a result of the extension the data volume in the figuring space, a magnificent enthusiasm of realizing more beneficial technique that go for securing, separating and planning the data signal is principal. electrophysiological data is noteworthy for investigation, management and clinical investigation in epilepsy and other essential issue. “eeg” data is a kind of biomedical sign dataset and clinical “big-data” that have "4 v" (volume, combination, speed and regard), which including more than 100 “multichannel” signal. without a doubt, which imperative to actualize successful methodology so as to oversee huge eeg datasets. one of the ordinarily utilized strategies as a part of dissecting data is ensample empirical mode decomposition (eemd) strategy which help in breaking down eeg flags yet this technique takes longer time if data are broke down successively. this work should answer the underneath inquiries: • what does the mapreduce and hadoop can offer as far as capacity and examination of eeg big-data? • how does the hadoop vary from typical programming methods in preparing the eeg bigdata? 1.2. the solution proposed in order to improve the adequacy of separating “eeg big-data” for all the additionally sympathetic and straightforwardness of considering patient cases, “eeg big-data” ought to be completed close by “hadoop” by using mapreduce technique. the use of mapreduce and “hadoop” on scattered structures, for instance, “cloud computing” can add to the basic advancement in clinical big-data planning and utilize. likewise, it will present new open entryways in the creating time of “big-data” examination and enhance the aftereffect of clinical “eeg big-data” explanatory gadgets. sahar mahdie klim al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 129137 (2017) 132 the change of the “hadoop” made it a great deal less requesting to consider and dismember immense measure the data in a favorable profitable way. the “hadoop” executes the use of the “map” and “reduce” shapes, that let the designer to control the data that they are enthused about examination. besides, hadoop plays out the work speedier, where it takes each one of the archives and explore every one of them meanwhile, however in regular programming the records ought to be poor down freely. additionally, “hadoop” obtain the code in a speedier and compelling course as differentiated and the standard programming technique. thusly, it is basic to outline the upsides of realizing the “hadoop” in the figuring space of taking care of “eeg big-data”, this procedure will agree to the clinical and eeg signal get ready examiners, to procure their required information and accomplish their destinations swiftly and definitely, with slightest tries. in addition, this proposed system will make it straightforward to manage them “eeg” huge data in improved way. this search shed the light on the points of interest that the “hadoop” and mapreduce had added to the preparing and the programming space. furthermore, it used an example of “eeg big-data” to be taken care of using “hadoop” server in light of the mapreduce method and depict an overhauled strategy for data use and examination in a capable, brisk, and correct way. this accomplishment, evaluated the planned approach of using the mapreduce methodology on “hadoop” server in light of flowed figuring structure, to set up the “eeg big-data” to make it basic for clinical individuals and “eeg” signals investigators to recuperate the required data for their work and analyzes, absolutely with brief era. this planned system and they got contributed occurs, which will be showed up in later ranges, could be considered as a distress in the clinical field specially the “eeg” signals taking care of. 1.3. paper organization next to this section, the second section will specify foundation focused on the issue understudy. the third section will the talk about the instruments, approach and methodology that are utilized as a part of this study and their choice criteria. the proposed approach and the assessment test will be examined in the fourth area. in addition, the fifth area will contain the outcomes got from the proposed approach and their examination notwithstanding correlations amongst the and the nearest related work, with a specific end goal to assess the commitment and upgrades that this study has advertised. at last yet essentially, the 6thsection will abridge the work demonstrate the conclusions got from this study. 2. evolution of big-data in the course of recent years, the growing usage of using web organizing, new improvements, for instance, the possibility of “internet of things” (iot) make huge measure of information that can yield extremely valuable data if fittingly managed. it is called as “big data”. these datasets portray voluminous measure of composed, semi sorted out and unstructured information. along these lines, “big data” has created to restrain the value, arrangement and velocity of datasets; in view of that reality, the conventional advances of planning information were not able. this is by virtue of it divided, hard to reach, excessively immense, move too fast, and unnecessarily trapped. pros evaluate that 80 to 90 of affiliations' information are unstructured and the measure of unstructured information is turning out to be rapidly and much of the time usually than composed database. therefore, routine programming methods, for example, “relational database management system (rdbms)”, and “sql” were ended up being too progressively to set up the volume of information in favorable path since they cannot oversee petabyte and exabyte of information. dataset is continually updating and making new information that they ought to be readied, the more quickly of information is being created, the more basic to have a base that can scale to process information as quick as it is changed and “big data” consolidate unstructured information that it doesn't stay in line segment of database. 3. proposed methodology the used electrophysiological information for this examination was gotten from, which record for patients inside the five days time of their specialist's office stay and release multi-channel dataset. remembering the true objective to record electrophysiological information, 30-40-channels are regularly included. each of these channels is sahar mahdie klim al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 129137 (2017) 133 made out of 20 “eeg”, 4 “ekg”, 1 channel for oxygen checking, 2 occupies are incorporated into respiratory hailing and 1 is used for watching circulatory strain. around, 20 edf records are exposed for each patient inside the 5 days cross period. each edf report is made out of information record and each information record contains seconds of sign demonstrated by a particular number of tests are showed up in record header and chronicled as cloud wave metadata [19]. in the aide, the information is changed over into an once-over and that in truth could save time while differentiating qualities and foresee delay in the run time as it has a record. in the wake of changing over the information to an once-over, the product designer would have the option of picking the information that are required. along these lines, the aide has diverse components, where it has a record, change over the substance to once-over and make the measure of the information more diminutive concurring the information which required. when the customer needs to intensify the range of the information, the cursor ought to be moved. regardless, this movement is not any more required as “java” can use to oversee content records that might be segregated by commas and space and a while later these information can carry on to the rundown by changing over the substance archive to an aide. by then, when moving to the diminishing or count, the customer can make the code that is required on the once-over that was made. the summary does not have a cursor since it is considered as a document that starts with zero and the once-over could be gathered into a key or a value. the transport of the information could be on more than one server so that if we rent from the “cloud” various servers, this information ought to be added to the cloud. by then, a request ought to be directed to accumulate the information inside the information coordinator. in this way, while selecting the aide decrease, the engineer needs to give the name of the particular yield and the way could be an ip deliver which is conferred to various diverse servers. the implies that required while coordinating an aide decrease are the underneath: 1. created database building 2. database inclusion. 3. dataset processing and looping. 4. building the guide work, which reduces that we did. there were particular classes. the principal class, that is the overall public class. the static class, which is fanned and rest mapper that reduces stage from “java”. the product design needs to choose the kind of the information and execute is to the mapper. 4. the experiment of evaluation “hadoop” is an engine that considers running techniques simply in a brief period. as a product engineer or an architect, it is fundamental to know the establishment of the “hadoop”; which suggests the spot of where each one of the records will be secured at. each one of the information can be secured in h-work coordinator and in case that the designer ne.eds to cha.nge the n.ame of the record, the earth route n.eed to cha.nge. in order to chan.ge the earth way, the course of the “hadoop” should be changed from windows settings. by then, to turn the path on a database, the database that the architect need to manage should have the sa.me st .ructure to create an authentic test on it. by then, remembering the ultimate objective to make the aide, the product build needs to consider the structure of the database, which could be a substance record, picture or some other course of action. the following stride that should be done is determining the course that i have for putting away every one of the data inside an data organizer. while managing the hadoop, every one of the data that we have as a content record will be gathered and assembled bit by bit inside the info envelope. it could be conceivable that we would have more than one organizer however the greater part of the envelopes ought to be as a content and ought to have the same structure. this is significant as though the software engineer needs to build up a little program; the calculation that we need to create to break down the data needs steady structure. along these lines, when we reach to the guide structure, every one of the data that enters that guide ought to have a consistent structure for more proficient investigation. in this manner, every one of the data in an organizer ought to have the same number of sections and the same data sort, while these datashould be composed in a specific arrangement. case in point, if the software engineer takes a bit of data as a number and after that it shows up in one document as a content, this would bring about a noteworthy issue. at that point, the “hadoop” will build the guide on every one of the documents that are found inside the sahar mahdie klim al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 129137 (2017) 134 info envelope, regardless of what number of organizers we have. presently, we should assemble a guide with a specific end goal to do a file (rundown) of the data. to develop this progression, the content document should be changed over to information or list, as this progression will add to min.imizing the span of the data and dispose of the considerable number of data that are not required. for our situation, we just need to know the pa.tient's id and the time that light was killed. in this manner, we are no more keen on the various data that are found in the rundown. notwithstanding the way that the guide is steady, we will have the capacity to extricate the data that we require from it as indicated by the kind of data that we need to separate from the guide. the work on the last stride is to create the yield record, which has every one of the qualities that have been determined by the developer. for our situation, we picked the estimations of which time has been killed after 12 pm as it were. inside the “hadoop”, there is an order that gives the data as per its accessibility, we simply call attention to the data and the yield organizer that are found inside the “hadoop”. it has been accounted for that the season of “cpu” for our d.ata was zero because of the little size of the documents that we have. the beneath square graph compresses the strategy took after amid the execution procedure. fig. 1. proposed approach block diagram the above blo .ck diagram contains the steps of the two phas.es, “map” and “reduce”. then the next section will show the obtained outcome and comparison between the proposed approach and the previous one. 5. experimental results in this search, we utilized the inputfiletemazepam_ effects_on_sleep.txt [24] keeping in mind the end goal to acquire the results.txt record. at that point, we utilized the map-reduce-eeg.java to lead the guide procedure and afterward create the diminish procedure keeping in mind the end goal to get the information that are of our fundamental attention. we were occupied with acquiring the information, where the time of lights turn off after 05:00am. the data underneath demonstrates the java file, start map phase eeg big-data entry data conversion divide and distribute data on multiple servers data ordering data compression end map phase. go to reduce phase start reduce phase enter query retrieve data select suitable data list selected data load requested data end sahar mahdie klim al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 129137 (2017) 135 map-reduce-eeg.java. the following is the “java” assessment c.ode test for the trial. 5.1. the function of the map that show the evaluation code for the map ph.ase. public void mapeeg (longwritable key, text value, o.utputcollector<text, text> output, reporter reporter) throwsioexception { string roweeg = value.tostring(); string curser = null; string tokenizereeg = new stringtok.enizer(line,"\t"); string var_agent= s.nexttoken(); while (eeg.hasmoretokens()) {curser= eeg.nexttoken();} string timeofsleep =curser; ou.tput.collect(new text(timeofsleep), new text(timeofsleep)); } 5.2. reducer class that show the “java” code for the reduce ph.ase. public st .atic class reduceeeg extends m.apreducebase implements reducer< text, text, text, text> { public void reducerrg( text key, iterator <text> values, ou.tputcollector<text,text> output, reporter reporter) throwsioexception {while (values.hasnext()) { textsec=va.lues.next();localtimeloctim= new localtime(sec ); if(loctim.isafter(localtime.morning)) { output.collect(key, new text(loctim)); }}} as indicated by the “hadoop” capacity above, we have initially extricated the java document that has every one of the records and data in it. at that point, we led the guide procedure to change over every one of the data to rundown that has record and in this way, making the correlation procedure simpler that it is utilized to be in typical programming. at that point, in the lessen procedure; we picked the qualities that the light turned off after 05.00am. the string line quality will be put away in the content document and it will take the last esteem token. the line will continue moving to the following worth token and after that give the estimation of the last token, where it generally take the last esteem and store it in “java” record. the underneath figures demonstrates the response time about in the wake of making the query utilizing the proposed strategy and contrasting it and the old data structure technique. fig. 2. experimental results request time. fig. 3. experimental results hit rates vs miss rates the previous figures demonstrates the pattern of the reply time for the experimental results, demonstrating the improved reply time of the proposed ap.proach in correlation with the conventional strategy for data structure. the previous results demonstrate clear enhancement on the reply time and precision of the retrieved data, with normal general improvement with average response time of 0.36s, and average hit rate of 93.33%. on the other hand, the old data structure method showed average response time of 2.37s and average hit rate of 83.30%. to have approximately 65% enhancement on the response time and 12% enhancement on the accuracy and hit rate. which is great contribution, especially when dealing with big data that contains huge about of stored and distributed data. sahar mahdie klim al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 129137 (2017) 136 6. conclusions hadoop is an engine that works alongside the mapreduce with a specific end goal to help the software engineer or designer to acquire the information that they require and bar the various data that they need not bother with. in any case, hadoop needs a server with excellent attributes to create the work and every one of the procedures that we have to perform. in this study, we utilized the utilization of the mapreduce strategy on hadoop server to process eeg big data and make the dispersion on cloud. accordingly, this has made it less demanding for examination and getting that information of concern.the analysis were actualized on hadoop, clear upgraded results were acquired and contrasted and customary information structure strategy, which demonstrated a normal of half improvement over the conventional technique. 7. references [1] londhe, s. r., mahajan, r. a., &bhoyar, b. (2013). overview on methods for mining high utility itemset from transactional database. international journal of scientific engineering and research (ijser), 1(4), 12. [2] adrian.a. big data challenges. 2013. database systems journal vol. iv, no. 3, 3140. [3] krishnan, k. (2013). data warehousing in the age of big data. newnes. [4] jin, q., liao, h., srinivasan, s., &xu, l. (2014). u.s. patent no. 8,903,762. washington, dc: u.s. patent and trademark office. [5] cloud security alliance. 2013. big data analytics for security intelligence. 1-22. [6] hernandez, m. j. (2013). database design for mere mortals: a hands-on guide to relational database design. pearson education. [7] barbulescu, m., grigoriu, r., halcu, i., neculoiu, g., sandulescu, v. c., marinescu, m., &marinescu, v. (2013, january). integrating of structured, semi-structured and unstructured data in natural and build environmental engineering. in roedunet international conference (roedunet), 2013 11th (pp. 1-4). ieee. [8] mayer-schönberger, v., &cukier, k. (2013). big data: a revolution that will transform how we live, work, and think. houghton mifflin harcourt. [9] birke, r., bjoerkqvist, m., chen, l. y., smirni, e., &engbersen, t. (2014). (big) data in a virtualized world: volume, velocity, and variety in cloud datacenters. in proceedings of the 12th usenix conference on file and storage technologies (fast 14) (pp. 177189). [10] vashist, s., & gupta, a. (2014). a review on distributed file system and its applications. international journal of advanced research in computer science, 5 (7). [11] das. t, kumar. m. big data analytics: a framework for unstructured data analysis. 2013. vol 5, 0975-4024. [12] lee, k. h., lee, y. j., choi, h., chung, y. d., & moon, b. (2012). parallel data processing with mapreduce: a survey. acmsigmod record, 40(4), 11-20. [13] bryan, b. a. (2013). high-performance computing tools for the integrated assessment and modelling of social–ecological systems. environmental modelling & software, 39, 295-303. [14] pourqasem. j, karimi. s and edalatpanah. s. comparison of cloud and grid computing. (2014). american journal of software engineering, vol. 2(1), 8-12. [15] mukhopadhyay, d., agrawal, c., maru, d., yedale, p., &gadekar, p. (2014, december). addressing name node scalability issue in hadoop distributed file system using cache approach. in information technology (icit), 2014 international conference on (pp. 321-326). ieee. [16] maniar, k. b., & khatri, c. b. (2014). data science: bigtable, mapreduce and google file system. international journal of computer trends and technology (ijctt), 16(03), 115-118. [17] vadivel.m&raghunath.v. 2014. enhancing map-reduce framework for bigdata with hierarchical clustering. international journal of innovative research in computer and communication engineering, 2 (1), 23209801. [18] raghupathi. w &raghupathi. v. 2014. big data analytics in healthcare: promise and potential. health information science and systems, 2 (3), 1-10. [19] tsai. c, lai. c, chao. h, vasilakos. 2015. a. big data analytics: a survey, journal of big data, 1-32. ��ي ���� �� � ���� 1، ا���د�13 �� ا���ارز � ا������� ا�� ،2017( 137-129( 137 ���� $�$�س "�! ا���� � ا�������)��ام &%��� ا����ت ا�(��� +�درا�� .���، : إدارة ا� � �ت ��ر ا���11�ت ا�)���0 ا��/ �+��� ��ي ������ ھ� � ا������ت�� / � ����ن ���� / ��� ا��� ��و����� sahar_mahdi@uomisan.edu.iq:ا���� ا �� ا��2 م "��%&%ل إ���� "!�� ��� و����� (��. �4 ,�3 ا������ت . ��, ة ا������ت، +��ف "(/(%, �. ا������ت ا�(�+� وا�(%ز, "!�� +�(* ��(�� ا���56 �. ا������ت��!�: إدارة ھ7ا ا��+ � +!%�� ط�� ���4 �4 إدارة ھ. ا�>)( ، ا�!�ق ا� �( �4 إدارة ا������ت �� ��ھ7ا . 7ه ا������ت ا�>)( � ام + �� ا�(�"�� �%س �4 ����/ ا������ت ا�>)( ا�(%ز, ,�? ا����" ا�(�%�� (� رس ا�� aا��� . ام �cدم ا���دوب و+(���" ��)�� + + �� �ھ7ه ا� ��d را� � ،�e�� 5 أظ��ت +��. واi* ,�? إدارة و����/ ا������ت ا�!�� ا�( � �4 ھ7ا ا��(. +!�� �� ,�? "����ت �ch%ذة �. &%ر ا��)!�f ا� ���د� �4 ����/ وإدارة �op ا������ت% ٥٠"(� ل +���. ���وي . ا�>)( ,�وھ% �� �%�4 ط�� ��� و���� �4 ا�����5 �: ا������ت . � �ر� "��!�ق ا . ا�>)( basement kind effects on air temperature of a solar chimney in baghdad iraq weather miqdam tariq chaichan department of machines & equipments engineering/ university of technology email: miqdam_tc@yahoo.com (received 28 february 2010; accepted 20 march 2011) abstract a solar updraft tower power plant (solar tower) is a solar thermal power plant that utilizes a combination of solar air collector and central updraft tube to generate an induced convective flow which drives pressure staged turbines to generate electricity. this paper presents practical results of a prototype of a solar chimney with thermal mass, where the glass surface is replaced by transparence plastic cover. the study focused on chimney's basements kind effect on collected air temperatures. three basements were used: concrete, black concrete and black pebbles basements. the study was conducted in baghdad from august to november 2009. the results show that the best chimney efficiency attained was 49.7% for pebbles base. the highest collected air temperature reached was 49ºc when using the black pebbles basement also.also, the maximum basement temperature measured was 59ºc for black pebbles. high increaments in collected air temperatures were achieved in comparison with the ambient air temperatures for the three basement kinds. the highest temperature difference reached was 22ºc with the pebble ground. keywords: solar chimney, basement effect, concrete, pebbles, storage efficiency. 1. introduction sun is the principal source of almost all kinds of energy, both conventional and non-conventional. the sun is approximately 1.4 million km in diameter and 150 million km from the earth. its temperature is close to 5500°c at its surface and emits radiation at a rate of 3.8 × 1023 kw. this power is supplied by nuclear fusion reactions near its core which are estimated to continue for several billion years. (lovegrove and dennis, 2006). the input of solar radiation to the biosphere is the source of energy which drives our weather systems and so in turn, winds, hydroelectric and biomass energy systems. solar radiation can be used directly for photovoltaic energy conversion and for solar thermal conversion (xinping, yang and hou, 2007). electricity can be generated from solar radiation through the following methods:  photovoltaic cells  solar thermal power  solar tower / chimney (bilgen and rheault, 2005). a recent development in solar energy is a solar tower/chimney. it is a method used for large-scale generation of electricity from solar radiation. the principle is very simple (onyango and ochieng, 2006). a solar chimney is an air-heating solar collector that runs automatically on sun power alone. it is based on the well known principle of greenhouse effect, chimney updraft effect, and wind turbine. air is heated by solar radiation under a low circular transparent or translucent roof opened at the periphery; the roof and the natural ground below it form a solar air collector (pretorius and kroger, 2005). in the middle of the roof a vertical tower is installed with large inlet at its base. the joint between the roof and the tower base is airtight. as hot air is lighter than cold air, it rises up the tower. suction from the tower then draws in more hot air from the collector, and cold al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 7, no. 1, pp 30 38 (2011) this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ miqdam tariq chaichan al-khwarizmi engineering journal, vol. 7, no. 1, pp 30 38 (2011) 31 air comes in from the outer perimeter (xinping, yang and hou, 2006). due to greenhouse effect, the air is warmed in the solar collector. the warm air is moves from the periphery of the solar collector towards its center in order to ‘’escape’ to upper layers of atmosphere through the solar chimney (fig.1). this moving stream of warm air leaves part of its thermodynamic energy to the air turbines that are geared with appropriate electric generators. an indicative diagram for a solar chimney power plant is shown in fig.1. in 1903, spanish colonel isidoro cabanyes first proposed a solar tower power plant in the magazine la energia electrica. one of the earliest descriptions of a solar tower power plant was written in 1931 by a german author, hanns gunther. beginning in 1975, robert e lucier applied for patents on a solar tower electric power generator. these patents were granted in australia, canada, and the usa between 1978 and 1981. the first studies on solar chimneys were reported in 1993 by bansal et al. they present a stationary state model to describe a solar chimney, consistent by a conventional chimney linked to an air solar heater. hirunlabh et al. report in 1999 the results of an experimental solar chimney, composed of a glass surface, air channel and a metallic black wall as collector surface. khedari et al. in 1999 made a comparative study among different configurations of solar chimneys classified as, roof solar collector, modified trombe wall, trombe wall and metallic solar wall. in 2003 ong and chow reported the experimental and theoretical results of a solar chimney similar to the hirunlabh one. fig.1. solar tower working principles. solar towers have a number of special features: 1. the collector can use all solar radiation, both direct and diffuse. this is crucial for tropical countries where the sky is frequently overcast (koonsrisuk and chitsomboon, 2006). 2. due to the soil under the collector working as a natural heat storage system, updraft solar towers can operate 24 hours on pure solar energy, at a reduced output at night. if desired, additional water tubes or bags placed under the collector roof absorb part of the radiated energy during the day and releases it into the collector at night. (ong and chow, 2003). 3. solar towers are particularly reliable and not liable to break down, in comparison with other power plants. turbines and generators subject to a steady flow of air are the plant's only moving parts. this simple and robust structure guarantees operation that needs little maintenance and of course no combustible fuel (onyango and ochieng, 2006). 4. unlike conventional power stations (and also some other solar-thermal power station types), solar towers do not need cooling water. this is a key advantage in the many sunny countries that already have major problems with water supply (haase and amato, 2005). 5. the building materials mainly concrete and glass needed for solar towers, are available everywhere in sufficient quantities. in fact, with the energy taken from the solar tower itself and the stone and sand available in the desert; they can be reproduced on site. energy payback time is two to three years (shyia, 2002). 6. solar towers can be built now, even in less industrially developed countries. the industry already available in most countries is entirely adequate for solar tower requirements. no investment in high-tech manufacturing plants is needed (schlaivh et. al., 2005). 7. even in poor countries, it is possible to build a large plant without high foreign currency expenditure by using local resources and workforce; this creates alarge number of jobs while significantly reducing the required capital investment and thus the cost of generating electricity (xinping, yang and hou, 2007). nevertheless, solar towers also have features that make them less suitable for some sites: a. they require large areas of flat land. this land should be available at low cost, which means that there should be no competing usage for this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ miqdam tariq chaichan al-khwarizmi engineering journal, vol. 7, no. 1, pp 30 38 (2011) 32 the land e.g, intensive agriculture (koonsrisuk and chitsomboon, 2006). b. solar towers are not adequate for earthquake prone areas in this case tower costs would increase drastically (direcksataporn, 2008). c. zones with frequent sand storms should also be avoided, as either collector performance losses or collector operation and maintenance costs would be substantial there (xinping, yang and hou, 2006). in the objective of this study was to examine the effect of basement types on the air temperatures of aprtotype solar chimney designed and constructed for this purpose, in baghdad autumn days. 2. experimental set up the solar tower’s prototype was built as shown in fig. 2 air is heated by solar radiation under a low circular transparent roof (6 meters dia) open at the periphery (2 cm high from ground); the roof and the ground below it form a solar air collector. in the middle of the roof that is a vertical tower (4 meters tall and 20cm dia) with large air inlets at its base (10 cm height from the ground). the joint between the roof and the tower base is airtight. as hot air is lighter than cold air, it rises up the tower. suction from the tower then draws in more hot air from the collector, and cold air comes in from the outer perimeter. continuous 24 hoursoperation can be achieved by placing a thermal collector ground. for this purpose three kinds of grounds were studied, the first was an ordinary concrete ground, which heats up during day-time and releases its heat at night. the second was selective black colored concrete ground to absorb more heat at daylight. the third basement was selective black colored pebbles known as aheat storage substance and for giving efficient air mixing by increasing its turbulance. the idea was to investigate the best basement material that makes solar radiation cause a daily constant updraft in the tower. the temperature of air under the transperace cover was measured by (6) six calibrated copperconstantan thermocouples distributed uniformly around the vertical chimney. also, the rising air temperature through the chimney was measured by means of caliprated thermocouples. these thermocouples were fixed in variable manner, to give acurate analysis of the moving air through the chimney. the first thermocouple in the group represents collected air temperature (tc). the temperature of the air entering the chimney (ta) was measured by thermometer fixed away from the chimney. the basements floor temperature (tf) was measured by means of three thrmocouples distributed in the west, south and east directions, with a distance of 1.5 metre from the centre of the collector; the avarage of these thermocouples readings was taken as (tf). temperatures were read by caloibrated digetal electronic thermometer, through a selector switch. fig. 2 represents prototype diminsions and thermocouple distribution, while fig. 3 shows a photographic picture for the tested prototype solar chimney. fig.2. schematic diagram of the solar chimney and thermocouples distribution. fig.3. the solar tower’s prototype. the experiments were conducted in iraqi autumn days, started on the first of august and finished on the end of november 2009. the tests were conducted in saydia city, west of baghdad. three grounds were prepared; the first one was ordinary concrete ground, the second one was ordinary concrete ground painted with selective black color, and the third was selective black colored pebble ground. table 1 represents the thermal properties for the used material. the this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ miqdam tariq chaichan al-khwarizmi engineering journal, vol. 7, no. 1, pp 30 38 (2011) 33 prototype chimney was fixed in each ground, for 10 days. temperature readings were taken, so for each ground there are readings for three months; the resultant average were undertaken to compare the three cases. temperature readings operation began at sun shine and continued after sunset until the basement reached its starting temperature. these temperatures demonstrated the thermal storage in the basement. table 1, typical thermal properties for tested materials (mc quiston et al). 2.1. system efficiency calculations solar tower system consists of three main parts: collector, tower and turbine. in this study no turbine was used, and the concentration was on thermal energy gathered by solar chimney collector by its various basements. in calculating system efficiency the procedure mintioned in (schlaich et al, 2005) was used . the basic function for solar chimney is to convert heat flow produced by the collector into kinetic energy. the n efficiency can be calculated by: total system efficiency = turbinetowercoll   ... (1) where: collector efficiency. tower efficiency. turbine efficiency. in this study there was no turbine to complete this conversion, and the focus was on the collector efficiency which is calculated by: … (2) ptot the pressure difference produced between collector outlet and ambeint air depends on the density difference of air caused by the temperature rise in the collector area and is calculated as follow: …(3) with: accollector area. hctower hight. ρaair density in ambient temperature. ρcair density in the tower. thus ptot increases with the tower hieght. …(4) the solar energy input. average solar intensity taken from iraqi meteorology organization for 24 hours of the tested period. this efficiency was used to compare the three basements in this study. the former equations illustrate a very important characteristic in the solar chimney; which is the chimney efficiency depends mainly on the chimney’s tower height. 3. results and discussion figures (4 to 6) represent the solar chimney behavior when concrete ground was used in the three months of study. the results show the air temperature increases with time, starting from sun rise, this increase was associated with an increase in the collected air (tc) and the basement (tf) temperatures. the maximum temperatures were achieved at 2 p.m. collected air was heated in this region (sun rise till 2 p.m.) by greenhouse effect; while the direct radiation heated the ground. in these hours the collected air was independent of the warm ground. fig.4. concrete basement and air temperatures at 11/9/2009). material density (ρ) kg/m3 conduct -ivity (k) w/m ºc conductance w/m2 ºc speci -fic heat kj/kg ºc concrete 20202180 3.0-3.5 0.92 pebble 2080 0.921.12 5.28 this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ miqdam tariq chaichan al-khwarizmi engineering journal, vol. 7, no. 1, pp 30 38 (2011) 34 fig.5. concrete basement and air temperatures at 7/10/2009. fig.6. concrete basement and air temperatures at 14/11/2009. all temperatures reduced after 2 o’clock at noon, until they reached the starting temperature after sun set. in this region the collected air depends on the basement to warm up. the thermal storage for the concrete ground was very limited and achieved temperature differences for about two hours after sun set. this limited time is due to the prototype chimney dimensions. it is believed that big collector area will give more thermal storage heat, and will introduce more working hours to the chimney. the maximum differnce between (tc) and (ta) was (19ºc). the maximum variation between air temperature (ta) and ground temperature (tf) for ordinary concrete case was about (25ºc) at 1 to 2 p.m. where the highest temperatures were acheived. the maximum (tf) reached was (56ºc) in august days. figures (7 to 9) represent the solar chimney behavior when selective black colored concrete ground was used. the average temperatures for three months operation period show that there were some improvements in temperature differences between ambient air and collected air, where the temperature got to (20ºc) at peak time. the black colored concrete ground absorbed more solar radiation, and heated more than ordinary concrete basement where (tf) reached amaximum temperature of about (57.6ºc) in august days. also at 7 a.m. they were (temperatures measurment starting point), there were differences between (tc) and (tf) more than in the other months. the effect of solar radiation is more effiecient in hotter days, which means more system efficiencies will be obtained in summer months. the thermal storage of black cloured concreate basement managed to continue warming collected air for three hours after sun set, despite the limited collector size. fig.7. black concrete basement and air temperatures at 13/9/2009. fig.8. black concrete basement and air temperatures at 9/10/2009. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ miqdam tariq chaichan al-khwarizmi engineering journal, vol. 7, no. 1, pp 30 38 (2011) 35 fig.9. black concrete basement and air temperatures at 16/11/2009. figures (10 to 12) demonestrate the solar chimney behavior when black colored pebbles basement was used. the figures show that there are some improvements in temperature differences; the maximum temperaure difference between (ta) and (tc) reached (22ºc) at the peak time. the black pebbles ground absorbed solar radiation, and heated more than ordinary concrete basement due to its higher specific heat. the maximum temperature obtained was (59ºc). this thermal storage managed to continue operating for five hours after sun set, despite the limited collector size. these results give black pebbles priority over ordinary and black concrete basements. as well as it proves that a suitable basement compined with suitable solar chimney design manage to operate for 24 hours. fig.10. black pebbles basement and air temperatures at 15/9/2009. fig.11. black pebbles basement and air temperatures at 11/10/2009. fig.12. black pebbles basement and air temperatures at 18/11/2009. the results demonstrate that the storage capacity of black concrete improved about 50% compared with ordinary concrete, while black pebbles improved this capacity with about 250% due to its thermal properties. fig.13 shows the chimney’s collector hourly efficiency variation for the three systems with operation time. because the studied system depends on solar energy, then it’s collecting time starts from sunrise and ends at sunset. the pebbles basement collecting efficiency surpasses the other cases. the thermal storage improved with this ground, and enable the chimney to work for more time. on the other hand, coloring the concrete ground with black upgraded the thermal storage and improved its efficiency. the rsults concluded that the efficiency of solar chimney depends this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ miqdam tariq chaichan al-khwarizmi engineering journal, vol. 7, no. 1, pp 30 38 (2011) 36 highly on the thermal storage capacity of its basement material. fig.13. average efficiency differences for day hour fot basment systems. 4. conclusions the practical prototype model of the solar chimney power plant was designed and constructed to investigate the influence of basement kinds on chimney’s air temperatures, in the region of baghdad iraq. the effects of storage parameter, such as the solar radiation, the ambient temperature, and the heat storage capacity for ground materials on the power plant operation time are also investigated. according to the results obtained from the proposed model, the following conclusions are drawn: 1the solar chimney power plant have a suitable basement (black colored pebble ground in this work) can achieve air heating for many hours operation after sun set. with suitable design the solar chimney power plant will manage to act 24 hours / day. 2the results show that black pebbles basement had better thermal storage quality than ordinary concrete or black concrete ground. 3although the chimney prototype size was limited, it gave high temperature difference between tc and ta which reached 22οc. the maximum tf reached was 59 οc when using black pebbles. this indicates the convenient of iraqi weather for this type of plants. 4painting the basement with selective black colour increased absorped solar radiation, and thereby improved the system efficiency. notation ac collector area h tower height average solar intensity ptot pressure difference produced between collector outlet and ambient air solar energy input greek letters ρa air density in ambient temperature ρc air density in the tower collector efficiency tower efficiency 5. references [1] bansal n k, mathur r and bhandari m s, 1993, solar chimney for enhanced stack ventilation, building and environment journal, vol. 28, pp: 373-377. [2] bilgen e and rheault j, 2005, solar chimney power plant for high latitudes. solar energy journal, vol. 79, pp: 449-458. [3] direcksataporn b, 2008, potential study of solar chimney power plant in northeastern region of thailand, technology and innovation for sustainable development conference, faculty of engineering, khon kaen university, thailand, 28-29 january. [4] haase m and amato a, 2005, development of double –skin façade system that combines airflow windows with solar chimney. the 2005 world sustainable building conference, tokyo, 27-29 september. [5] hirunrabh j, kongduang w, namprakai p and khendari j, 1999. study of natural ventilation of houses by a metallic solar wall under tropical climate, renewable energy journal, vol. 18, pp: 109-119. [6] günther h, 1931, in hundert jahren – die künftige energieversorgung der welt” kosmos, gesellschaft der naturfreunde, franckh'sche verlagshandlung, stuttgart. [7] khedari j, boonsri b and hirunlabh j, 1999. ventilation impact of a solar chimney on indoor temperature fluctuation and air change in a school building. energy and buildings journal, vol. 32, pp: 89-93. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ miqdam tariq chaichan al-khwarizmi engineering journal, vol. 7, no. 1, pp 30 38 (2011) 37 [8] koonsrisuk a and chitsomboon t, 2006, effect of tower area on the potential of solar tower, the 2nd joint international conference on "sustainable energy and environment (see2006)", 21-23 nov, bangkok, thailand. [9] lovegrove k and dennis m, 2006, solar thermal energy systems in australia, international journal of environmental studies, vol.63, no. 6, pp: 791-802. [10] ong, k.s. and c.c. chow, 2003, performance of solar chimney. solar energy, vol. 74, pp: 1-17. [11] onyango f n and ochieng r m, 2006, the potential of solar chimney for application in rural areas of developing countries, fuel journal, vol. 85, pp:2561-2566. [12] pretorius j p and kroger d g, 2005, critical evaluation of solar chimney power plant performance. solar energy journal, vol. 80, pp: 535-544. [13] schlaivh j, bergermann r, schiel w and wienrebe g, 2005, design of commercial solar updraft tower systems-utilization of solar induced convective flows for power generation, journal of solar energy engineering, vol. 127, pp: 117-124. [14] xinping z, yang j and hou g, 2007, experimental study of temperature field in a solar chimney power setup. applied thermal engineering journal, vol. 27, pp: 2044-2050. [15] xinping z, yang j and hou g, 2006, simulation a pilot solar chimney thermal power generating equipment, renewable energy journal, vol. 32, pp: 16371644. [16] shyia a k, 2002. parametric study of solar chimney performance. m.sc. thesis, university of al-mustansiriya, 2002. [17] mcquiston f c, parker j d and spitlr j d, 2005, heating , ventilating and air conditioning –analysis and design, john wiley & sons, inc. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ 38 ، صفحة1، العدد 7الھندسیة المجلد مجلة الخوارزمي مقدام طارق جیجان 30 )(2011 38 العراق تأثیر نوع القاعدة على درجات حرارة مدخنة ھوائیة في أجواء مدینة بغداد مقدام طارق جیجان الجامعة التكنولوجیة /قسم ھندسة المكائن والمعدات miqdam_tc@yahoo.com: البرید االلكتروني الخالصة مستحث بالحمل، " سیة وأنبوب سحب مركزي لتولید تدفق ھواء مسخن شمسیامدخنة الھواء أو البرج الشمسي تركیبة من مجمعات الھواء الشمتستخدم .والذي یمكنة تحریك توربینات متعددة المراحل لتولید الكھرباء ركزت الھدف من ھذا البحث ھو تقدیم نتائج عملیة لنموذج مدخنة شمسیة ذو كتلة حراریة، إذ تم استبدال السطح الزجاجي بغطاء بالستیكي شفاف، ت ة سوداءاللون راسة على تأثیر نوع قاعدة المدخنة على درجات حرارة الھواء، ولقد استخدمت ثالثة أنواع من القواعد، قاعدة كونكریتیة، قاعدة كونكریتیالد .٢٠٠٩یلول لغایة نوفمبر أوقاعدة من الحصى االسود اللون، وتمت الدراسة في أجواء بغداد من شھر وأعلى درجة حرارة . عند استخدام قاعدة من الحصى األسود %49.7لمدخنة وأعلى درجة حرارة تم الوصول لھا كانت تبین الدراسة أن أفضل كفاءة ل لقد تم ، 59ºc، كما كانت أقصى درجة حرارة قیست لھذة القاعدة ھي باستخدام قاعدة الحصى األسود أیضا 49ºcأمكن الوصول لھا كانت للھواء المجمع في درجات حرارة الھواء المجمع مقارنة مع درجات حرارة الھواء الجوي للقواعد الثالثة المدروسة، وأعلى فرق في درجات الحرارة الوصول لزیادة كبیرة .بأرضیة من الحصى األسود 22ºcأمكن الوصول لھ كان this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ 110120 al-khwarizmi engineering journal al-khwarizmi engineering journal,vol. 12, no. 3, p.p. 110120 (2016) experimental and theoretical study for performance enhancement of air solar collectors by using different absorbers ahmed a. mohammad saleh* taher abbas rashid** *, ** department of mechanical engineering / university of technology * email: aamsaleh60@yahoo.com ** email: taheraltemimi@yahoo.com (received 18 december 2014; accepted 28 march 2016) abstract an experimental and theoretical study has been done to investigate the thermal performance of different types of air solar collectors, in this work air solar collector with a dimensions of (120 cm x90 cm x12 cm) , was tested under climate condition of baghdad city with a (43° tilt angel) by using the absorber plate (1.45 mm thickness, 115 cm height x 84 cm width), which was manufactured from iron painted with a black matt. the experimental test deals with five types of absorber: conventional smooth flat plate absorber , finned absorber , corrugated absorber plate, iron wire mesh on absorber and matrix of porous media on absorber . the hourly and average efficiency of the collectors were investigated for three values of mass flow rates (0.016 kg/s to 0.027 kg/s) for each type of collector and then the porosity for the last collector type was tested by changing the porosity of porous media. a typical air solar collector has been studied theoretically to build a standard software for testing any type of air solar collectors with local weather data . from the experimental study it can be seen by using some obstacle material to the air flow (fins, corrugated absorber plate, iron wire mesh porous media on the absorber) could be enhanced the efficiencies not less than 4 % for finned type and 8 % for corrugated and 25 % for mesh and 30 % for porous media comparing with flat plate (smooth) collector . theoretically, the results showed that the collector with high convention heat transfer coefficient porous media has high hourly efficiency about (η = 56 %) and iron wire mesh on absorber ( η = 52 % ), on the other side the minimum performance occurred in the flat plate absorber (η = 28 %). comparison of results reveals that the theoretical predictions agree reasonably well with experimental results. and the difference between the theoretical and experimental efficiency in general was between (1─ 15 %). keywords: air solar, collector performance, pours media. 1. introduction solar air heaters are very simple and cheap, therefore is most widely used as a collection devices of solar energy. the thermal efficiency of solar air heater has been found to be very poor because of their inherently low heat transfer capability between the absorber plate and the air flowing through the duct. several designs of solar air heaters have been developed over the years in order to improve their performance. providing artificial roughness on the absorber plate is an effective technique to enhance the heat transfer coefficient.[1] amer et al. (2010) , [2] induced a study for the effect of absorber surface shape of solar air collector (flat v-corrugated , sinusoidal wavecorrugated,rectangular-corrugated) (1×1×0.1m) the results show that the best heat transfer coefficient enhancement is (63%) for (v corrugated plate) compared with the flat plate. ahmed a. mohammad saleh al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 110120 (2016) 111 and the maximum drag friction coefficient is occurred at (v-corrugated) at (re=8000). bhandari et. al. (2012), [3], made a comparative study of performance of different types of flat plate solar air heaters. the results showed that the analysis of various types of solar air heaters for the same mass flow rate in a double pass finned solar air heater has the highest efficiency. and, it was concluded that the values of mean absorber plate temperature (tpm) and fluid outlet temperature decrease with the increase in mass flow rate. abdullah et. al. (2013), [4], showed in this work numerical solutions of the heat balance equations for single glazed flat plate collectors using computer program. the study shows that the empirical relations of (ut) predict the values close to numerical solutions only for certain assumed conditions and cause large errors in the calculation of top heat loss factor and useful energy for other range of variables. chabane et. al. (2013), [ 5], reported that heat transfer of a solar air heater duct can be increased by providing artificial roughness on the heated wall (i.e. the absorber plate). the results show that the maximum efficiency values obtained for the 0.016 kg/s with and without using fins were 51.50 % and 43.94% respectively. peng et. al. (2010), [6], theoretically and experimentally analyzed the performance of a solar air heater with fins attached to the absorber plate. the aim is to enhance the thermal performance of the solar air heater with a cheap and accessible collector design that has a long durability. for this purpose, an experimental setup was installed . in this study. 25 pin-finned collectors and a flat plate clear collector were discussed. it was concluded that with 19 m3/h air flow rate, the pin-fin arrangement in a solar air collector could increase the heat transfer coefficient up to three times when compared with flat-plate collector. ahmed m. et. al. [7], (2007) studied the effect of ambient and inlet temperature to the solar air heater on the performance of solar air heater equipped with porous material. the analysis and design of the solar air heater to be operated in cold climatic regions. it was shown that a collector thermal and exergetic efficiency of about 85 % and 39 %, respectively, could be obtained for ambient temperature of 20º c , while the thermal efficiency will be around 55 % and the exergetic efficiency of 40 % for ambient temperature of -10º c. the aim of present study is to review the design and to analyze the heat transfer of air solar collector. experimental-theoretical study presents a comparison of a solar collector with smooth absorber plate , corrugated absorber plate and with using fins attached on the absorber plate and with using wire mesh & porous media to enhance the heat transfer coefficient. 2. experimental setup the solar air collector facing south was mounted in baghdad (33.3 latitude) as in the fig. 1 , with tilt angle 43 degree from horizontal ,the length of the collector equals to 1200 mm, width is 900 mm and the depth is 120 mm. (fig. 2) . an insulation layer (fiber glass) of 50 mm thickness is mounted on the back side of the collector, whereas sides are insulated with 30 mm of fiber glass. and outlet is placed as a one hole round duct 100 mm dia. in upper part in which the blower is directly connected. 2.1. housing and absorber the collector housing is the container that provides structural integrity for the collector assembly. absorber plate painted with black matt (flat black paint, (α = 0.92 to 0.98, ) [8] .it's been used single-glazed 4 mm thickness, (120 cm length x 89 cm width). the insulation has been used is fiberglass with conductivity ( ki= 0.037 w/m.c°[9] ). backinsulation thickness is 50mm, and edge insulation thickness is 30mm. centrifugal fan blower, radial type, has been used , a nominal flow rate of fan 0.0255 m3/s are connected to the collector. this fan it has special vanes to regulate the mass flow rate. ahmed a. mohammad saleh al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 110120 (2016) 112 fig. 1. the collector air solar. 2.2 measurement apparatus � solar radiation meter. � dual function anemometer & intelligent thermometer. � temperature data logger(labjack with thermistors). � thermistors silicon type ( lm35) . fig. 2. schematic air solar collector. 3. procedures of experiment below mentioned the measurements procedures to have to be performed to collect data of testing experiment : 1. temperature measurements 2. air flow measurements 3. solar radiation measurements solar radiation and temperatures have been recorded from sunrise to sun set every 5 minutes for five types of collector absorber surfaces, as in fig. 3, which they are: 1. smooth flat surface 2. fined surface 3. corrugated surface 4. wire mesh on surface 5. porous media on surface and using three different mass flow rates on every type of collector by changing fan inlet suction vanes to achieve the specific mass flow rate as shown in the following table 1 . table 1, readings of five types of collector surfaces. type date flow ( kg/s) matrix weight flat 27/1/2014 13/2/2014 12/2/2014 0.027 0.022 0.019 corrugated 30/1/2014 22/2/2014 21/2/2014 0.027 0.022 0.019 fined 31/1/2014 10/2/2014 11/2/2014 0.027 0.022 0.019 wire mesh 25/1/2014 19/2/2014 20/2/2014 0.022 0.019 0.017 (830 g) porous media 18/2/2014 14/2/2014 17/2/2014 0.022 0.027 0.016 (585 g) (885 g) (885 g) fig. 3. schematic views of the five types of plate surfaces. ahmed a. mohammad saleh al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 110120 (2016) 113 4. experimental calculations 4.1. air mass flow rate ( ) 4.2. useful energy ( ) 4.3. collector efficiency (η) hourly solar radiation, useful energy 5. theoretical analysis the present work involves a comparative study of performance analysis of different types of flat plate air solar collectors. a fortran program code is built to carry out the whole analysis. the effect of mass flow rates, inlet temperature and intensity of solar radiation on the performance of solar air heaters are also investigated in the present study, see appendix . 6. flow chart of computer program many relations have been obtained in the previous section to analyze the operation of air solar collector. fortran computer program has been classified into three parts which are the main program, radiation subroutine and collector subroutine to obtain the theoretical performance of air solar collector , fig. 4, shows flow chart of the mathematical model. fig. 4. flow chart of computer program. 7. results and discussion 7.1. flat smooth absorber plate the fig. 5, shows the relation of (tai ,tao, tpm ) inlet air ,outlet air and plate temperatures respectively with time, it can be seen that the maximum value reached at midday (tai =30 c° ,tao =50 c°, tpm =80 c°) that because being the incident radiation maximum at the same time. the hourly solar radiation value i, and hourly useful energy value qu, along the day for flow rate 0.019 kg/s shown in fig. 6 , both starting with the minimum value ( i= 1.7 mj/m2 & qu= 0.2mj/m2 ) and reaching maximum value ( i= 4.2 mj/m2 & qu= 1.3 mj/m2 ) at midday. ahmed a. mohammad saleh al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 110120 (2016) 114 fig. 5. the inlet air ,outlet air and plate temperatures with time of day at 0.022 kg/s flow rate. fig. 6. hourly useful energy and hourly solar radiation with time of day at 0.019 kg/s flow rate. 7.2. the efficiency curves of five types the performance curves of experimental study for five types of air solar collectors tested in this study which are flat plate, finned, corrugated, mesh and porous types are shown in fig. 6 and their values given table 2. table 2, efficiency of five types absorber type average efficiency flat 26% finned 30% corrugated 34% mesh 51% porous 56% from fig. 7 can be seen that the collector efficiency of finned plate is higher than that of flat plat, due to the fact that the fins increase the surface area and heat transfer coefficient, and extension of the air flow path by creating new airflow passages between the vanes. it was also found that the curves tends to decrease slightly this attributed to the combined effects of the solar radiation and the top losses. and from the comparison between flat plate and corrugated plate showed that the efficiency of corrugated was higher than that of flat plate, because the air flowing across a corrugated absorber plate creates turbulence along the plate, which increases the convective heat transfer coefficient , and also it can be seen that the efficiency has a tendency to decrease , same reason of finned plate case . it is further observed that the collector efficiency of mesh type was higher than the efficiency of the conventional air heater flat plate, this is a reasonable observation for the enhancement of the heat transfer. it is also observed that the efficiency curves are almost constant which is attributed to the fact that, solar radiations are progressively absorbed and stored by the layers of wire mesh and the remaining radiations are absorbed by the absorber plate. if the collector performance of porous and flat plate type are compared, it will be found that the efficiency of porous is clearly higher than that of flat plate ,the reason that not only the absorber plate but the matrix material also works as the absorber of solar radiation, therefore, the heat energy due to absorption of solar radiation is distributed throughout the packed material and the absorber plate and dissipated now more effectively to the flowing fluid due to very large surface area being in contact with the flowing fluid in a packed collector as compared to a plane collector where in only the absorber plate surface is in contact with the flowing fluid. another reason that the temperature difference between the porous material and air is less as compared to the temperature difference between the absorber plate and air in case of collector without matrix as well as for the conventional collectors because the matrix is shading the solar radiation. ahmed a. mohammad saleh al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 110120 (2016) 115 fig. 7. the performance curves (efficiency) of five types air solar collector with time of day for 0.022 kg/s mass flow rate. fig. 8. efficiency with time of day for different values of porosity for porous media absorber. 7.3. effect of porous material it is reveal that the thermal efficiency of packed collector (porous +wire mesh) increases as porosity decreases. this may be due to the decrease in porosity increases the effective heat transfer area. therefore, the heat transfer coefficient between the matrix and flowing air increases resulting in higher thermal efficiency. also, decrease in porosity reduces the flow channeling, i.e. increase in turbulent of the air flowing through the packed passage resulting in improved thermal performance. it is important to explore the influence of porosity on the thermal performance of air solar collector as shown in fig. 8. there is no doubt that the working with the optimum porosity is also required . 7.4. theoretical study the performance curves of five types of air solar collectors models tested in this study. the theoretical efficiencies can be seen in fig. 9 . it's clear that the efficiencies were slightly degreased at midday. this is a reasonable observation due to the fact that the increase of solar intensities will increase the mean plate temperature as shown in fig. 10, and then increase the losses. this has a significant influence on performance efficiency of the air solar collector . a comparison can be made between the results of fig. 7 & fig. 9, to verify the degree of theoretical predictions agreement with the experimental results , as it can be seen that the difference between the theoretical and experimental efficiency was between ( 1─ 15 %) , so its acceptable result with a good agreement. fig. 9. the performance curves (efficiency) of five types air solar collector with time of day for 0.022 kg/s mass flow rate. fig. 10. the mean plate temperature with time of day for rate for flat plate absorber. ahmed a. mohammad saleh al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 110120 (2016) 116 8. conclusions the conclusions can be drawn from the experimental and analytical studies as the following : � the hourly solar radiation, useful energy exhibit parallel changes with the incident radiation .i.e. they depend directly on the amount of the solar radiation for any air flow rate . � the efficiency of the collector improves with increasing mass flow rates for every types of absorbers due to an enhanced heat transfer to the air flow. � the heat transfer and thermal performance of solar air heater with artificial roughness(finned ,corrugated) gave higher values than that of non artificial roughness solar collector ,hence artificial roughness, are recommended . � solar air collector with( porous, mesh) material in the air pass gives maximum thermal efficiency among the solar collector types . � it is reveals that the theoretical predictions agree reasonably well with experimental results. the differences between theoretical and experimental efficiencies were a non-significant. � a standard fortran software has been performed to test any type of air solar collector in local weather data before starting to manufacturing or using . appendix: solar radiation calculation , [10] a. latitude angle (ϕ) it is the angular location north or south of the equator, for baghdad city equal 33.3o. b. declination angle (δ) c. surface azimuth angle (γ) the deviation of the projection on a horizontal plane of the normal to the surface from the local meridian ,zero due south. d. surface tilt angle (β) the angle between the collector plane and the horizontal ( 0o ≥ β ≥ 180o ). e. hour angle (ω) the angular displacement of the sun east or west of the local meridian due to rotation of the earth on its axis at 15o per hour, morning negative and afternoon positive. f. sunset hour angle(ωs) and no. of daylight hours the sunrise hour angle is the negative of the sunset hour angle, and determined using equation: ωssss it also follows that the number of daylight hours is given by : no. of daylight g. solar time solar time − standard time � 4�lst − lloc) + e where e � 229.2�0.000075 + 0.001868 cos bʹ − 0.032077 sin bʹ − 0.014615 cos 2bʹ − 0.04089 sin 2bʹ) where : bʹ � �n – 1 ) h. solar altitude angle (αs) i. incidence angle (θ) cos θ � cos θz cos β + sin θz sin β cos �γs −γ) j. zenith angle (θz) , k. solar azimuth angle (γs) total solar irradiation ,[1] beam radiation calculation cos θ idn = diffuse radiation calculation = c idn fss fss = (1 + cos β ) ⁄ 2 ahmed a. mohammad saleh al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 110120 (2016) 117 ground reflected radiation calculation =( ρg. fsg fsg = (1 – cos β ) ⁄ 2 collector overall heat losses … where: collector efficiency factor, [11] dh: hydraulic diameter = calculation heat transfer coefficient for flat plate , [10] for fined plate ,[12]. for corrugated plate , [13] for porous and mesh.[14] heat removal factor ,fr,[10]. the useful energy,[10] fully fresh, outside air ) mean plate temperature calculation, [10] collector efficiency nomenclature english a apparent solar radiation at air mass = 0 ap apparent collector area arc aspect ratio for solar collector channel , height to width af air flow section area b the atmospheric extinction coefficient. p porosity of matrix media bʹ parameter of the time equation pt pitch of wire mesh or (pours media) c dimensionless value represent to the average ratio of diffuse to normal beam radiation. dw wire diameter cpa specific heat capacity dh hydraulic diameter e the equation of time f` collector efficiency factor fr heat removal factor fsg angle factor between the surface and the earth fss angle factor between the surface and the sky gt total incident solar radiation gb beam solar radiation gd diffuse solar radiation gr ground reflected solar radiation ahmed a. mohammad saleh al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 110120 (2016) 118 h collector thickness h heat transfer coefficient h∞ convective heat transfer coefficient for air wind flowing over the surfaces of the collector h1 convection heat transfer coefficient between glass cover and air flow in the channel h2 convection heat transfer coefficient between absorber plate and air flow in the channel hr radiation heat transfer coefficient between absorber plate and glass cover i hourly solar radiation idn the direct normal solar radiation ith total horizontal irradiation it total hourly irradiation k thermal conductivity ki back insulation thermal conductivity ks side insulation thermal conductivity l collector length lst the standard meridian for the local time zone lloc the longitude of the given location ma mass flow rate n number of covers n number of day in year nua nusselt's number for air ntu rate number of transfer units pr prandtl number qu useful energy rea reynolds number for air s solar radiation absorbed by a collector t temperature t air channel thickness tc cover temperature tg glass cover temperature t∞ ambient air temperature tai air flow inlet temperature tao air flow outlet temperature tp plate temperature tpm average plate temperature ut top loss coefficient ub back loss coefficient uf heat removal loss coefficient of fluid ul thermal resistance between absorber plate and ambient u° thermal resistance between fluid and ambient us side loss coefficient v velocity of ambient wind va average air velocity vt total volume vs solid volume w collector width xi back insulation thickness xsi side insulation thickness greek symbol α absorptivity αs solar altitude angle β surface tilt angle γ surface azimuth angle γs solar azimuth angle δ declination angle εp absorber plate emissivity εg glass cover emissivity τg glass cover transmission η collector efficiency θ incidence angle θz solar zenith angle µa viscosity ρ reflectance ρa air density ρg ground reflectivity σ stefan-boltzman constant ϕ latitude angle τα transmisitance absorptiance ω hour angle ωs sunset hour angle 9. references [1] ashrae applications handbook, "solar energy use" ,(si),chapter ,32, (1999). 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[10] duffy, j. a. and beckman, w. a., “solar engineering of thermal processes”, fourth edition. john wiley & sons, new jersey, (2013). [11] rockendorf, g., schreimuller, k.r, &wetzel, w., " the difference of collector test results between the heat loss measurement and the methods with radiation", proc. ises solar world congress, budapest, hungary, vol. 5: 323-328 , (1993). [12] f. p. incropera and d. p. dewitt, " fundamentals of heat and mass transfer", 6th ed. hoboken, nj john wiley, ( 2007). [13] m. n. metwally, h. z. abou-ziyan and a. m. el-leathy," performance of advanced corrugated-duct solar air collector compared with five conventional designs", technology, helwan university, cairo 11718, egypt, (1996). 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( ........ al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 8, no. 2, pp 30-41(2012) experimental and numerical study of crack effect on frequency of simple supported beam luay s. al-ansari muhannad al-waily ali m. h.yusif al-hajjar department of mechanical engineering/college of engineering/ university of kufa (received 26 july 2011; accepted 30 january 2012) abstract in this research the natural frequency of a cracked simple supported beam (the crack is in many places and in different depths) is investigated analytically, experimentally and numerically by ansys program, and the results are compared. the beam is made of iron with dimensions of l*w*h= (0.84*0.02* 0.02m), and density = 7680kg/m3, e=200gpa. a comparison made between analytical results from ansys with experimental results, where the biggest error percentage is about (7.2 %) in crack position (42 cm) and (6 mm) depth. between rayleigh method with experimental results the biggest error percentage is about (6.4 %) for the same crack position and depth. from the error percentages it could be concluded that the rayleigh method gives close results to experimental than ansys. also it is found that the frequency of beam when the crack is in the middle position is less than the frequency with crack near the end position. keywords: vibration beam, crack beam, health monitoring, experimental vibration beam, cracks effect beam frequency. 1. introduction the importance of the beam and its engineering applications is obvious, and it undergoes many different of loading. many types of loading may cause cracks in the beam. these cracks and their locations effect on the shapes and values of the beam frequency. recently these topics are so prevailing in the industry of spacecraft, airplanes, wind turbines, turbines, robot arm and many other applications. many studies were performed to examine the vibration and dynamic of cracked beams; one of them was shen and pierre[1],who present a finite element approach which make it possible to predict in the first few eigen frequencies due to cracks (pairs or single open cracks).the change in the first natural frequency with crack depth is matched closely by the present finite element approach and also with the experimental results. also, shen and pierre [2] derived the equation of motion with associated boundary conditions for uniform bernoulli-euler beam. the resulting equation is solved for simple supported and cantilevered beams with single edge cracks by galerkin and ritz procedure; they matched the theoretical results with the experimental and finite element results and they match closely. chati et . al. [3] modeled the non-linearity as a piecewise-linear system. in an attempt to define effective natural frequencies for this piecewise linear system, the idea of a 'bilinear frequency' is utilized. the finite element method is used to obtain the natural frequencies in each linear region. choondros et. al [4]studied the dynamics of a cracked fixed-free bar with a breathing crack in longitudinal vibration. they showed in results the eigenfrequency changes due to a single open-edge breathing crack in order to depend on the bilinear character of the system. they tested their method fordifferent bar configurations corresponding to crack location, crack depths, cross-section dimensions, andpoisson's ratio. the natural frequencies obtained from this model agree well with experimental results. choondros et. al [5]used a continuous cracked beam vibration theory for predication of changes in transverse vibration of simply supported beam luay s. al-ansari al-khwarizmi engineering journal, vol. 8, no. 2, pp 3041(2012) 31 with a breathing crack. they found that the changes in vibration frequencies for fatigue breathing crack are smaller than the ones caused by open cracks. utilizing aluminum beams with fatigue cracks for experimental setup they compared the results with the analytical. chondros[6]used a continuous cracked beam vibration theory for predication of changes in dynamic characteristic due to loading conditions and vibration amplitude. he used the numerical results to correlate the analytical results for lumped crack beam vibration analysis for aluminum and steel beams with open cracks. he supported the theoretical result by experimental results for the same cases. cam and et. al. [7] studied ,experimentally and theoretically, the effect of the crack on vibration of cracked beam. they used echo method for predication the size and location of the crack in cracked beam. they found that the theoretical results (ansys) agreed with experimental results. in this paper, three approaches are employed, an analytical approach is compared with experimental result and with that gained numerically by ansys program to verify the results. the objective of this paper is to study the effect of crack depth and position on the natural frequency of the simple supported beam and to find the best method that gives good results to be compared with experimental results. 2. theoretical approach 2.1. analytical approach (rayleigh method) rayleigh method is a good method and simpler than the other analytical methods for finding the natural frequencies. it includes calculating the kinetic energy and potential energy of the system. where the kinetic energy can be calculated by integration the mass through length of the beam and the potential energy by integration the stiffness through the length of the beam. so one can get from the above, s. s. rao [12]:                  1 1 2 1 1 0 2 0 2 2 2 2 ))(( )( n i ii n i ii l l ym ymg dxxya dx dx xyd ei   … (1) where,  is the natural frequency of beam. e is the modulus of elasticity of beam (n/m2). i is the second moment area od cross section area of beam (m4).  is the mass density of beam (kg/m3). a is the cross section area of beam (m2). g is the gravity acceleration (9.81 m/s2). mi is the mass in each rayleigh divided point of beam. yi is the deflection in each rayleigh divided point of beam. by calculating the deflection of the beam(y(x)) using the following steps: 1. dividing the beam into (n) parts (i.e. (n+1) nodes). 2. calculating the delta matrix [δ]((n+1)* (n+1)). 3. calculating the mass matrix [m]((n+1). 4. calculating the deflection at each node by multiplying delta matrix and mass matrix ([y] (n+1)= [δ]((n+1)* (n+1)) [m]((n+1)) after applying the boundary conditions. the analytical results are solved using matlab. where a matlab program that simulated the rayleigh method is written in order to calculate the first natural frequency of any beam (different materials, different dimensions and different shape). 2.2. numerical approach (finite elements method) in this method, the finite elements method was applied by using the ansys program(ver.13). the three dimensional model were built and the element (solid tet 10 node 187) were used. generally the number of nodes was approximately (1250-1300) and the number of elements was (550-600). a sample of meshed beam is shown in fig. 1. luay s. al-ansari al-khwarizmi engineering journal, vol. 8, no. 2, pp 3041(2012) 32 a) meshed beam without crack. b) meshed beam with crack at 12 cm from left end. c) meshed beam with crack at 22 cm from left end. d) meshed beam with crack at 32 cm from left end. e) meshed beam with crack at 32 cm from left end. fig. 1. a sample of a meshed beam. 3. experimental approach the (tm16 universal vibration apparatus) from tq company is employed in this study and is shown in fig. 3. the dimensions of the specimen used are (l*w*h=0.84*0.02 *0.02 m) as shown in fig. 2. the material of the specimen was stainless steel (code no.: 314, robert l. norton [16]) with density of (7680 kg/m 3 ), calculate by divided the weight of beam per volume of beam, young modulus (200 gpa) and poisson’s ratio (0.3). the crack was created in the specimens with certain dimensions of crack ;(see table (1)). table 1, dimensions of the cracks that used experimentally. specimen no. crack location (m) crack length (m) crack width (m) crack depth (mm) 1 0.12 0.2 0.0015 0 2 4 6 8 10 2 0.22 0.2 0.0015 0 2 4 6 8 10 3 0.32 0.2 0.0015 0 2 4 6 8 10 4 0.42 0.2 0.0015 0 2 4 6 8 10 5 0.54 0.2 0.0015 0 2 4 6 8 10 6 0.64 0.2 0.0015 0 2 4 6 8 10 7 0.74 0.2 0.0015 0 2 4 6 8 10 luay s. al-ansari al-khwarizmi engineering journal, vol. 8, no. 2, pp 3041(2012) 33 fig. 2. dimension and crack depth and crack position of samples test. l w h c ra ck d ep th crack position (a) dimensions of sample (b) sample of beam (c) different crack position luay s. al-ansari al-khwarizmi engineering journal, vol. 8, no. 2, pp 3041(2012) 34 fig. 3. the universal vibration apparatus. motor added mass left supported right supported velocity meter sample (beam) (a) the universal vibration apparatus. (b) motor. (c) added mass. (d) velocity meter. (e) left and right supported. luay s. al-ansari al-khwarizmi engineering journal, vol. 8, no. 2, pp 3041(2012) 35 table 2, natural frequency with different crack position and crack depth. crack position (cm) crack depth (mm) frequency (hz) error exp. and ansys (%) error exp. and rayleigh (%) experimental ansys rayleigh method 12 0 143.74 148.81 145.2758759 3.5 1.06 2 141.42 148.7 145.2784708 5.15 2.73 4 146.805 148.46 145.2810655 1.13 1.04 6 141.99 148.01 145.2836602 4.2 2.3 8 142.5665 147.39 145.2862548 3.4 1.9 10 139.75 146.5 145.2888493 4.8 3.96 22 0 143.74 148.81 145.2758759 3.5 1.07 2 153.57 148.8 145.2784708 3.1 5.4 4 149.4 148.77 145.2873931 0.42 2.75 6 152.85 148.69 145.2931524 2.7 4.9 8 149.4 148.61 145.2989122 0.53 2.7 10 141.42 148.43 145.3046725 4.95 2.7 32 0 143.74 148.81 145.2758759 3.5 1.07 2 150 148.65 145.2784708 0.9 3.15 4 139.2 148.17 145.2873931 6.4 4.4 6 139.75 147.35 145.2931524 5.4 3.96 8 142.56 146.03 145.2989122 2.4 1.9 10 138.144 144.03 145.3046725 4.26 5.18 42 0 143.74 148.81 145.2758759 3.5 1.06 2 140.3 148.54 145.2886394 5.87 3.6 4 141.3 147.77 145.3014064 4.6 2.8 6 136.59 146.44 145.3141768 7.2 6.4 8 140.3 144.43 145.3269508 2.9 3.6 10 141.99 141.44 145.3397282 0.39 2.4 fig. 4. the comparison between the experimental and ansys results at different crack depths when the crack lies at (12 cm) . fig. 5. the comparison between the experimental and ansys results at different crack depths when the crack lies at (22 cm) . 100 110 120 130 140 150 160 0 2 4 6 8 f re q u en cy ( h z) . crack depth (mm). ansys experimental linear 100 110 120 130 140 150 160 0 2 4 6 8 f re q u en cy ( h z) . crack depth (mm). ansys experimental linear luay s. al-ansari al-khwarizmi engineering journal, vol. 8, no. 2, pp 3041(2012) 36 fig. 6. the comparison between the experimental and ansys results at different crack depths when the crack lies at (32 cm) . fig. 7. the comparison between the experimental and ansys results at different crack depths when the crack lies at (42 cm) . fig. 8. the comparison between the experimental and rayleigh method results at different crack depths when the crack lies at (12 cm) . fig. 9. the comparison between the experimental and rayleigh method results at different crack depths when the crack lies at (22 cm) . fig. 10. the comparison between the experimental and rayleigh method results at different crack depths when the crack lies at (32 cm) . fig. 11. the comparison between the experimental and rayleigh method results at different crack depths when the crack lies at (42 cm) . 120 125 130 135 140 145 150 155 160 0 2 4 6 8 f re q u en cy ( h z) . crack depth (mm). rayleigh method. experimental linear 120 125 130 135 140 145 150 155 160 0 2 4 6 8 f re q u en cy ( h z) . crack depth (mm). rayleigh method. experimental linear 120 125 130 135 140 145 150 155 160 0 2 4 6 8 f re q u en cy ( h z) . crack depth (mm). rayleigh method. experimental linear 120 125 130 135 140 145 150 155 160 0 2 4 6 8 f re q u en cy ( h z) . crack depth (mm). rayleigh method. experimental linear 100 110 120 130 140 150 160 0 2 4 6 8 f re q u en cy ( h z) . crack depth (mm). ansys experimental linear 100 110 120 130 140 150 160 0 2 4 6 8 f re q u en cy ( h z) . crack depth (mm). ansys experimental linear luay s. al-ansari al-khwarizmi engineering journal, vol. 8, no. 2, pp 3041(2012) 37 fig. 12. the comparison between the experimental and ansys results at different crack position when the crack depth is (2mm). fig. 13. the comparison between the experimental and ansys results at different crack position when the crack depth is (4mm) . fig. 14. the comparison between the experimental and ansys results different at crack position when the crack depth is (6mm) . fig. 15. the comparison between the experimental and ansys results at different crack position when the crack depth is (8mm). fig. 16. the comparison between the experimental and ansys results different at crack position when the crack depth is (10mm) . fig. 17. the comparison between the experimental and rayleigh method results at different crack position when the crack depth is (2mm) . 60 70 80 90 100 110 120 130 140 150 160 0 10 20 30 40 50 f re q u en cy ( h z) . crack position (cm). ansys experimental linear 60 70 80 90 100 110 120 130 140 150 160 0 10 20 30 40 50 f re q u en cy ( h z) . crack position (cm). ansys experimental linear 60 70 80 90 100 110 120 130 140 150 160 0 10 20 30 40 50 f re q u en cy ( h z) . crack position (cm). ansys experimental linear 60 70 80 90 100 110 120 130 140 150 160 0 10 20 30 40 50 f re q u en cy ( h z) . crack position (cm). ansys experimental linear 60 70 80 90 100 110 120 130 140 150 160 0 10 20 30 40 50 f re q u en cy ( h z) . crack position (cm). ansys experimental linear 0 20 40 60 80 100 120 140 160 0 10 20 30 40 50 f re q u en cy ( h z) . crack position (cm). rayleigh method. experimental linear luay s. al-ansari al-khwarizmi engineering journal, vol. 8, no. 2, pp 3041(2012) 38 fig. 18. the comparison between the experimental and rayleigh method results at different crack position when the crack depth is (4mm). fig. 19. the comparison between the experimental and rayleigh method results at different crack position when the crack depth is (6mm). fig. 20. the comparison between the experimental and rayleigh method results at different crack position when the crack depth is (8mm). fig. 21. the comparison between the experimental and rayleigh method results at different crack position when the crack depth is (10mm). fig. 22. relationship between natural frequencies and crack depths for different crack position (12, 22, 32, 42 cm). ansys results. fig. 23. relationship between natural frequencies and crack position for different crack depths (0, 2, 4, 6, 8, 10 mm). ansys results. 0 20 40 60 80 100 120 140 160 0 10 20 30 40 50 f re q u en cy ( h z) . crack position (cm). rayleigh method. experimental linear 0 20 40 60 80 100 120 140 160 0 10 20 30 40 50 f re q u en cy ( h z) . crack position (cm). rayleigh method. experimental linear 0 20 40 60 80 100 120 140 160 0 10 20 30 40 50 f re q u en cy ( h z) . crack position (cm). rayleigh method. experimental linear 0 20 40 60 80 100 120 140 160 0 10 20 30 40 50 f re q u en cy ( h z) . crack position (cm). rayleigh method. experimental linear 141 142 143 144 145 146 147 148 149 150 0 2 4 6 8 10 f re q u en cy ( h z) crack depth (mm) crack position=12 cm crack position=22 cm crack position=32 cm crack position= 42 cm 141 142 143 144 145 146 147 148 149 150 0 7 14 21 28 35 42 f re q u en cy ( h z) crack position (cm) crack depth=0 mm crack depth=2 mm crack depth=4 mm crack depth=6 mm crack depth=8 mm crack depth=10 mm luay s. al-ansari al-khwarizmi engineering journal, vol. 8, no. 2, pp 3041(2012) 39 4. results and discussion a comparison made between analytical results from ansys with experimental results shows a good approximation where the biggest error percentage is about (7.2 %) in crack position (42 cm) and (6 mm) depth, as illustrated in fig. 7. and the comparison between rayleigh method with experimental results shows a good approximation where the biggest error percentage is about (6.4 %) in crack position (42 cm) and (6 mm) depth, as illustrated in fig. 11. figs. 4, 5, 6, and 7. explain the comparison between theoretical results (ansys) and experimental results for natural frequency and how it changes with crack depth for different crack position (12, 22, 32, and 42 cm) where the natural frequency decreased with increasing crack depth for the same crack position because of the decreasing of stiffness of the beam. figs. 8, 9, 10, and 11. show the comparison between rayleigh method and experimental results for natural frequency and how it changes with crack depth for different crack position (12, 22, 32, and 42 cm) where the natural frequency decreased with increasing crack depth for the same crack position because of decreasing of stiffness of the beam. figs. 12, 13, 14, 15, and 16. the explain the comparison between theoretical results (ansys) and experimental results for natural frequency and how it changes with crack position for different crack depth (2, 4, 6, 8, and 10 mm) where the natural frequency decreased with increasing crack position for the same crack depth because of the decreasing of stiffness of the beam. figs. 17, 18, 19, 20, and 21. explain the comparison between rayleigh method and experimental results for natural frequency and how it changes with crack position for different crack depth (2, 4, 6, 8, and 10 mm) where the natural frequency decreased with increasing crack position for the same crack depth because of the decreasing of stiffness of the beam. generally from all the figures one can see that the natural frequency decreases with increasing crack depth for different crack positions because of the changing in stiffness of the beam. and the rate of decreasing for experimental is close for different crack positions. for ansys the rate of decreasing of natural frequency is the biggest in crack position (42 cm). and, for rayleigh method the rate of decreasing is close for different crack positions, as shown in figs. 22. and 23. and table (2). 5. conclusion from the results shown in the figs. 4 to 23, the following concluding marks are observed: 1a comparison made between analytical results from ansys with experimental results shows a good approximation where the biggest error percentage is about (7.2 %) in crack position (42 cm) and (6 mm) depth, as shown in fig. 7. 2the comparison between rayleigh method with experimental results shows a good approximation where the biggest error percentage is about (6.4 %) in crack position (42 cm) and (6 mm) depth, as shown in fig. 11. 3from the error percentages in table 2, the rayleigh method gives close results to experimental than ansys. 4the crack in the beam has an effect on the stiffness of the beam; this will affect the frequency of the beam. so, with the increasing of the crack depth, the stiffness of beam will decrease and this will cause a decreasing in the natural frequency of the beam. 5the position of crack in the beam near the middle of the beam has more effect on the stiffness and natural frequency of beam from the other positions (near to the ends of the beam), i.e. frequency of the beam when the crack is in the middle position has a lower frequency of the beam with respect the cracks near to the end position. 6. references [1] shen, m. -h. h and pierre c. . "modes of free vibrations of cracked beams", paper (of 46 pages) presented to um-meam, (1986). [2] shen, m. -h. h and pierre c. . "free vibrations of beams with a single edge crack", journal of sound and vibration, 170(2), pp. 237-259. (1994). [3] chati, m., rand, r. and mukherjee, s. "modal analysis of a cracked beam", journal of sound and vibration, 207(2), pp. 249-270. (1997). [4] chondros t. g., dimarogonas a. d. and yao j " longitudinal vibration of a bar with a breathing crack", engineering fracture mechanics, pp.503-518, 1998. [5] chondros t. g., dimarogonas a. d. and yao j. "vibration of a beam with a breathing crack" journal of sound and vibration, 239(1), pp. 57-67. (2001). luay s. al-ansari al-khwarizmi engineering journal, vol. 8, no. 2, pp 3041(2012) 40 [6] chondros t. g. "the continuous crack flexibility model for crack identification" blackwell science ltd., fatigue fact matter 24, pp. 643-650, 2001. 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(2012 )30 41 ، صفحة2، العذد 8 مجلة الخىارزمً الهنذسٍة المجلذلؤي صادق محمذ 41 دراسة تحلٍلٍة وعذدٌة لتأثٍر الشك على التردد الطبٍعً للعتبات رات التثبٍط البسٍط لؤي صادق محمذ مهنذ لفتة الىائلً علً محمذ حسٍن خبيعة انكىفة/ كهية انهُذسة/ لسى انهُذسة انًيكبَيكية الخالصة جى في هزا انجحث دساسة جأثيش انشمىق عهى انحشدد انطجيعي نهعحجبت اندبسئة ثحشية حيث جى دساسة جأثيش يىلع وعًك انشك عم انحشدد انطجيعي نهعحجة عشض *طىل) وجى يمبسَة انُحبئح يع ثعضهب انجعط نعحجة يصُىعة يٍ انفىالر ثإثعبد. (ansys)ورنك ثطشيمة عًهية ،وجحهيهية ،وعذدية ثبسحخذاو ثشَبيح حيث وخذ اكجش ansysجى يمبسَة انُحبئح انًسححصهة يٍ ثشَبيح .(ρ=7680kg/m3)وكثبفة ( e=200gpa) وخىاص 0.02m*0.02*0.84)=سًك * 6.2و وخذ اكجش َسجة خطب هي . ، وجًث كزنك يمبسَة انُحبئح انًسححصهة يٍ طشيمة سايهي وانعًهي(يى6)وعًك (سى42)نًىلع شك % 7.2َسجة خطب هي وخذ أٌ وكزنك . ansysيٍ ليى َست انخطأ يًكٍ االسحُحبج اٌ طشيمة سايهي جعطي َحبئح الشة نهعًهي يٍ طشيمة . (يى6)وعًك (سى42)نًىلع شك % .جشدد انعحجة عُذيب يكىٌ انشك في يُحصفهب الم يٍ جشدد انعحجة عُذيب يكىٌ انشك ثبنمشة يٍ أطشافهب اسيل وفلك واسامة ونزار al-khwarizmi engineering journal,vol. 12, no. 2, p.p. thermal behaviour of aseel basim alubaidi *,***,****department of **department of (received 3 june 2015; accepted 27 abstract polymer additives binder system provides the efficient energy storage materials and this paper studies the thermal energy storage to enhance paraffin wax thermal conductivity, pvoh as a material which high conductivity was employed. weight of paraffin wax was dispersed with pvoh heterogeneously (50/50, 67/33, 75/25, and 80/20) wt. ratio method. both base materials (polyvinyl alcohol and paraffin wax) (dsc) under non-isothermal conditions, the pvoh and paraffin wax base material. transition temperature (tg) for pvoh reached 20 pvoh suppress the thermal stability of conductivity enhancement using leedisk conductivity which increases thermal conductivity of apply change in phase with wide range of temperatures low, compared to that of paraffin only enhancing the thermal storage characteristics of paraffin. a wax/pvoh system acts as strength body absorbance percent was achieved by use both solutions (100% h2o) for all pure and composite material system p ambient conditions (air/ moisture) for composite system rather than pure keyword: pvoh/ pw system, thermal energy storage (tes) 1. introduction thermal energy storage (tes) applied in solar power have become fields of research in recent years, according to their impact of day and night on solar thermal energy storage, therefore, a recent development of professional energy storage materials will directly influence the utilization in solar storage [1-3]. in other hand if a single phase thermal khwarizmi engineering journal,vol. 12, no. 2, p.p. 1826 (2016) of paraffin wax/poly vinyl alcohol composite material aseel basim alubaidi* falak o. abas** raghad a.abass nazar j. abdulredhi**** department of material engineering /university of technology department of chemical engineering /koya university falak_usama@yahoo.comemail: ** ragad_2015@yahoo.comemail:*** (received 3 june 2015; accepted 27 january 2016) system provides many properties useful in thermal energy storage (tes) then developed and green strength bodies system. energy storage property for polyvinyl alcohol (pvoh) / paraffin wax enhance paraffin wax thermal conductivity, pvoh as a material which high conductivity was employed. paraffin wax was dispersed with pvoh heterogeneously at different additive weights wt. ratio respectively. the composite material was prepared using materials (polyvinyl alcohol and paraffin wax) were scanned using differential scanning calorimeter conditions, the result was analysed to determine the thermal transition the thermal decomposition of pvoh and waste paraffin wax pvoh reached 209ᴼc rather than wax of 60ᴼc respectively pvoh suppress the thermal stability of pvoh/waste paraffin wax composites. afterward disk techniques. composite materials pvoh/paraffin thermal conductivity of waste paraffin wax as a heat storage media apply change in phase with wide range of temperatures, and the highest decreased ratio of phase only. therefore, pvoh, added to paraffin which has significant potential for enhancing the thermal storage characteristics of paraffin. strength body resistance to sever contact of both air and moisture then a by use both fourier transform infrared spectroscopy (ftir for all pure and composite material system pw/pvoh, the results shows high resistance to for composite system rather than pure materials (pvoh and p thermal energy storage (tes) property, thermal behaviour, green strength bodies materials that become an important , according to impact of day and night on solar thermal development of energy storage materials will directly ar storage systems single phase thermal energy storage materials require a large storage space, cause reduces a storage property [4,5] investigation occurred on thermal energy storage materials that focuses on phase (pcms), and only several results these systems [6-10]. pcms have low thermal conductivity, that prevents load changes in the charging and disch processes [11], and obtain excellent thermal al-khwarizmi engineering journal (2016) paraffin wax/poly vinyl alcohol composite raghad a.abass*** university of technology thermal energy storage (tes) then developed paraffin wax (wpw) blends. enhance paraffin wax thermal conductivity, pvoh as a material which high conductivity was employed. a fixed weights ratios of pvoh/pw prepared using wetted pressing differential scanning calorimeter result was analysed to determine the thermal transition temperature of paraffin wax proved that high respectively. this result shows that fterward examines the thermal materials pvoh/paraffin wax have a high thermal paraffin wax as a heat storage media and this allows to , and the highest decreased ratio of phase-change heat is very has significant potential for air and moisture then a moisture ftir) techniques and moisture the results shows high resistance to materials (pvoh and pw). green strength bodies. energy storage materials require a large storage usefulness of thermal , therefore, a wide on thermal energy storage focuses on phase-change materials several results are applied in 10]. pcms have low thermal that prevents any problems of rapid load changes in the charging and discharging obtain excellent thermal aseel basim alubaidi al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 1826(2016) 19 properties. many studies have proposed various techniques for enhancing the thermal conductivity of pcms, such as adding metallic or non metallic particles with high thermal conductivity [12-15], inserting fins [16-18], incorporating porous or expanded materials [19-27], inserting fibrous materials [28-31], and incorporating macro-, micro-[32]. these methods are mentioned for enhancing the thermal conductivity of pcm involves adding high-conductivity materials to improve the thermal conductivity of pcms. thermal energy storage (tes) system is considered to be a suitable technology to store excess energy that would otherwise be wasted and used it for another time [1]. the system consists of material that capable to store thermal energy in the form of heat or cold (as insulation system applications). based on its phase change, the thermal energy storage can be classified as sensible heat, latent heat and thermo-chemical energy storage. among these types of energy storage, latent heat thermal energy storage (lhtes) system is a more attractive technology due to its higher density of energy storage capabilities, compared with conventional sensible heat thermal energy storage (shtes) system, that have smaller volume and less weight for a same amount of energy stored. a lot of studies are achieved by researcher in this fields usually use salt hydrates, paraffin and organic compounds as storage material [2].where less of materials having low thermal conductivity and insufficient time for melting and solidification process that reduces the overall power of the heat storage device and limiting the application of materials[3]. studies of thermal energy storage materials have been attracting more and more attention from all over the word. and these materials can be categorized into sensible heat storage materials, latent heat storage materials and thermal chemical materials. latent heat thermal energy storage uses phase change materials pcms of much higher heat storage density and extremely smaller temperature variation during phase change process, compared with sensible heat storage materials. if a comparison are done between inorganic pcms, organic pcms materials that have chemical thermal and a proper phase change temperature range, little or no super cooling, lower vapour pressure, nontoxicity, noncorrosivity, and excellent thermal stability. therefore, pcm is one of the most preferred forms of thermal energy storage materials of wide applications in this field of solar energy storage. fatty acids and paraffin wax (pw) are good organic pcms [18-20] due to their desirable characteristics such as high latent heat of fusion, negligible super cooling, low vapour pressure in the melt, and stability. the use of synthetic polymer materials has caused significant environmental problems. polyvinyl alcohol (pvoh) it is well known as a synthetic biodegradable polymer [8] and possesses excellent mechanical properties [9] its biodegradability in various microbial environments has been reported, and pvoh is one of the best options to be blended with other material [10]. pvoh is a versatile polymer, and it may be the only synthesised polymer with a backbone that consists primarily of –oh bonds that is absolutely biodegradable. pvoh is also an interesting water-soluble synthetic polymer with a broad range of applications. due to the solubility and biodegradability of pvoh, pvoh films are increasingly used in packaging applications [13] however, the biodegradability of pvoh depends on its degree of hydrolysis and its molecular weight. pvoh has the advantages of good film formation, strong conglutination and high thermal stability. in recent years, pvoh has been increasingly applied in the material industry. mettawee, et al [21], conduct a study to examine a method of increasing the thermal conductivity of paraffin wax by adding aluminum powder. the average particle diameter of aluminum powder used was 80 µm. tests performed by varying mass fraction of aluminum powder which are 0.1, 0.3, 0.4, and 0.5 of the total mass of paraffin waxaluminum for using in a solar collectors system. hamdani, et al [23] investigated characteristics of melting heat transfer of latent heat thermal storage unit with finned tube. the experimental results show that heat transfer characteristics presenting similarity for heat exchanger tube. polyvinyl alcohol (pvoh) is a high potential technology material with professional properties as strong, durable and high crystallinity structure [1]. with a high melting point at 230ºc compared to polyethylene of temperature ranges 117-135ºc according to the high level of hydrogen bonding in the crystals [2]. polymer blends is a well-used technique to modify their properties, as low in cost [3]. a recent study done by sreedar et al., 2005 [29] reported that incorporation of pvoh into starch had changed the thermo mechanical properties of the material and thus modified the polymer structure at both molecular and morphological levels [6, 7]. aseel basim alubaidi al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 1826(2016) 20 the aim of this work is to 1. design and develop efficient thermal energy storage, green strength composite materials system by using waste material to solve this environmental problem. 2. try different additives content of pvoh of good formation, strong conglutination and high thermal stability with paraffin wax. 3. optimization the additives content on thermal energy storage composite system (pvoh/wpw) according to their thermal and chemical properties. 4. scanning their stability point by use dsc, ftir, and leedisk techniques. 5. applied final optimum system in preparation of solar cells (thermal storage energy materials). 2. experimental 2.1. materials 1. paraffin wax: waste material collected locally from damping wastes of homes (domestic wastes) high molecular weight hydrocarbon compound of low melting point reached 6070o c. 2. polyvinyl alcohol: high purity compound of high hydroxyl active groups (dp 1799, average molecular weight: 145,000; hydrolysis rate: 90%; ph: 4.5-7 and density of 1.3g/cm3). 3. vaseline for ease holding of prepared composite material. 4. distilled water for chemical absorbance laboratory tests. 2.2. instruments 1. dsc (differential scanning calorimeter) 131evo – setaram: in order to estimate the change in phase for base material paraffin and polyvinyl alcohol (tg). 2. ftir (fourier transform infrared spectroscopy) 27tensor/ bruker : in order to estimate the intersurface morphology of polymers mean active group such as (co-, oh-, cl-, etc) for both base materials paraffin and polyvinyl alcohol. 3. leedisk technique: in order to estimate the thermal conductivity for thermal energy storage composite system (pvoh/ wpw). 4. press instrument: for preparation of composite system (pvoh/ wpw) before tests. 2.3. procedures 2.3.1. preparation and scanning of base material both base materials were analyzed by using both dsc and ftir techniques before preparing composite material in order to evaluation thermal stability and ambient resistance conditions where fixed weight for both samples are introduced in above scanning instruments. non-isothermal crystallization behaviours of pvoh, p using 131evo – setaram dsc and the weight of samples were approximately 7.5 mg. the sample were placed in aluminum pans and initially heated at the rate of 10oc/min from 25oc to 200oc under nitrogen atmosphere and held for 5 minutes to remove previous thermal history. afterward nonisothermal crystallization was investigated by cooling these samples from 200ᴼc to 25oc at constant cooling rates of 10ᴼc/min and it was heated again under the same temperature as in the first heating. all the thermograms shown refer to the second heating tg transition temperature .the absorbance (transmittance) inverse wave length cm -¹ in order to give absorbance values for activity groups (co-, oh-, cl-, etc). 2.3.2. preparation of thermal energy storage materials composite system a fixed amount of paraffin wax as (2 g) are exposure to moisture ambient reached (50%) then were mixing with different weight (2, 4,6,8) g of high thermal stability and high active hydroxyl group polyvinyl alcohol (pvoh) by use mechanical mixer for 30 min then heating composite material at 50ᴼc for 15 min afterward putting them in a suitable oily moulds , finally pressing them strongly at 10 ton loading , then output the final efficient energy thermal storage samples , left them for 24 hrs before any tests and an experimental design weight ratios shown in table (1),also figure (1) shows abase materials (pvoh, wpw) and composite system (pvoh/ wpw). aseel basim alubaidi al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 1826(2016) 21 table 1, show the experimental design for thermal energy storage composite system base material wpw/ g 0 2 2 2 2 2 base material pvoh/ g 2 2 4 6 8 0 design composite system pvoh/wpw wt. ratio 100 / 0 50/50 67/33 75/25 80/20 0/100 fig. 1. show base material (pvoh, pw) and composite system (pvoh/pw) a: show base pvoh crystals. b: show base paraffin wax (pw). c: show thermal energy storage composite system (pvoh/pw) 2.4. methodology thermal and chemical properties were achieved for thermal energy storage composite system (pvoh/pw) as thermal conductivity by using leedisk instrument for prepared samples of (1 cm thickness and 3cm dia.) dimensions. the prepared composite system applied between two copper disks then heating these disks afterward reading the change in temperatures by applying accumulated temperature load until failure of specimen occurred from (increasing temperature). chemical properties: this type of test is determined by immersion of both base and prepared composite system in natural solutions (100% h2o) for 0, 24, 48, 72, and 96 hrs respectively at 30°c afterward recorded the change in weight every 24 hrs in order to calculate the moisture percent in each samples and absorbance values to check which of samples is more chemically stable than others (optimum one).use the following relation below: moisture (%) = (wi – wd / wi) x 100 ... (1) where: wi, and wd estimate the weight for samples initially and after immersing in distilled water in (g). 3. results and discussion 3.1. scanning of base material the scanning of base materials (pvoh and pw) achieved as heat transfer characteristics of storage in the form of transition temperature, melting or freezing processes. from this result using paraffin wax as a thermal storage material shown in figure (2). it can be seen from the graph, at the beginning of heating, the measurements at tg point show the temperature increases rapidly until reach the melting temperature paraffin wax and then starts to slow down. it can be stated that at the beginning of heating, hot paraffin wax absorbs sensible and then followed by the absorption of latent heat which takes place at a temperature nearly constant ,paraffin wax is used as core material of latent heat storage media[1-3]. pvoh (100/0) showed relatively large and sharp endothermic peak at about 209ᴼc this related to its experimental melting point of pvoh (100/0) sample while the theoretical melting value of all hydrolyzed pvoh is 230°c. it could see that the melting temperature observed from the result was lower than theoretical one; this may be affected by the plasticizer and other chemical content in the sample [1-3] as shown in figure (3). fig. 2. shows a dsc scanning result for paraffin wax base material. a b c aseel basim alubaidi fig. 3. shows a dsc scanning result for polyvinyl alcohol base material. 3.2. preparation and characterization of thermal energy storage materials composite system the thermal conductivity is an important property of phase change materials (pcms) due to the rate of energy storage. pcms are used for thermal energy storage in environments with wide rang in temperature variation. ther thermal conductivity of these materials in both solid and liquid states at temperature range for experimental results are shown in figure (4) , where the additives of pvoh to paraffin are improved their thermal conduction performance of the paraffin wax, and the additive weight ratio 80/20 pvoh/pw to the paraffin is the best selection one. then the thermal conductivity performance of the paraffin wax was mainly enhanced due to the higher thermal conductivity of additives compared with pure pvoh pvoh material have higher water uptake than pw, and this water are increased with increasing immersion time and pvoh ratio. then the hydroxyl group (4.57%), which is responsible about the absorption water in the prepared composites. therefore, a higher content weigh ratio led to higher water being absorbed, at few days of immersion. figure (5) shows a rapid moisture uptake, afterward become straight constant relation the optimum samples that give high absorbance to moisture percent were 80/20 pvoh/pw respectively. al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 22 fig. 3. shows a dsc scanning result for polyvinyl 3.2. preparation and characterization of storage materials the thermal conductivity is an important property of phase change materials (pcms) due to the rate of energy storage. pcms are used for thermal energy storage in environments with wide rang in temperature variation. therefore, the thermal conductivity of these materials in both solid and liquid states at temperature range for experimental results are shown in figure (4) , where the additives of pvoh to paraffin are improved their thermal conduction performance raffin wax, and the additive weight ratio 80/20 pvoh/pw to the paraffin is the best selection one. then the thermal conductivity performance of the paraffin wax was mainly enhanced due to the higher thermal conductivity of additives compared with pure pvoh. the pvoh material have higher water uptake than pw, and this water are increased with increasing immersion time and pvoh ratio. then the 7%), which is responsible about the absorption water in the prepared gher content weigh ratio led to higher water being absorbed, at few days of immersion. figure (5) shows a rapid moisture uptake, afterward become straight constant relation the optimum samples that give high absorbance to moisture percent were 80/20 fig. 4. show the thermal conductivity values for all base pvoh, pw, and composite system pvoh/pw. fig. 5. show the absorbance for moisture percent for all base pvoh, pw and composite system pvoh/pw at different weight immersion time. 3.3. ftir instrument the ftir spectra of pvoh (figure 6) showed two peaks at 2955 cm-1 and 2847 cm to -nh stretching, where the c=o stretching at 1019 cm–1, and -nh bending between 1462 cm and 1377 cm–1 respectively. also wagging plane has 572 cm is 2955 cm–1 and 2842 cm hand the ftir for pva material has been showed a broad peak around 3425 cm indicating the stretching of hy peaks 2955 cm–1, 2842 cm h group. then peaks appeared at 1019 cm 1377 cm–1 indicated the c alcohol groups and ester. finally the appearance for peak at 2947 cm–1 incstrume proved that appearance of hydrocarbon chromophore in the esterified product [33]. according to the ftir results of paraffin wax (pw) in figure 7, it could see that the specialist peaks of the paraffin and polyaniline could be 0 0.01 0.02 0.03 0.04 0.05 0 2 k ( w /m ᴼ c wt. ratio for pvoh/wpw 0 10 20 30 40 0 50m o is tu re c o n te n t (% ) time of immersion (hr) 50/50 (pvoh/wpw) 75/25 (pv)h/wpw) 100/0 (pvoh/wpw) khwarizmi engineering journal, vol. 12, no. 2, p.p. 1826(2016) mal conductivity values for all base pvoh, pw, and composite system pvoh/pw. fig. 5. show the absorbance for moisture percent for all base pvoh, pw and composite system pvoh/pw at different weight ratio of pvoh and the ftir spectra of pvoh (figure 6) showed and 2847 cm–1 according nh stretching, where the c=o stretching at nh bending between 1462 cm–1 respectively. also -nh outside the wagging plane has 572 cm–1, and c-h stretching and 2842 cm–1recpectivly. in other hand the ftir for pva material has been showed a broad peak around 3425 cm–1 incstrume which indicating the stretching of hydroxyl groups but, , 2842 cm–1 referred to stretch ch group. then peaks appeared at 1019 cm–1 and indicated the c-o stretch as secondary alcohol groups and ester. finally the appearance incstrume proved that the appearance of hydrocarbon chromophore in the according to the ftir results of paraffin wax (pw) in figure 7, it could see that the specialist peaks of the paraffin and polyaniline could be 4 6 wt. ratio for pvoh/wpw 0 20 40 60 100 150 time of immersion (hr) 67/33 (pvoh/wpw) 80/20 (pvoh/wpw) aseel basim alubaidi al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 1826(2016) 23 noticed after 200, 400, 600, 800 and 1,000 cycles. also the peaks around 2960–2850 cm−1 and 1465 cm−1 show carbon hydrogen stretching and bending absorption, respectively. the c–h bending group is absorbed as ch3 group at 1381 cm−1 and ch2 rocking is absorbed at 729 cm−1 respectively in order confirm the linear saturated aliphatic structure of the paraffin wax [34].consequently, these results indicated that the reaction between pvoh materials and the ambient is not significant. fig. 6. the ftir spectra of polyvinyl alcohol (pvoh) base material. fig.7. the ftir spectra of paraffin wax (wpw) base material. 4. conclusions 1. the addition of high thermal conductivity (pvoh) material could able to increase thermal conductivity of paraffin wax as a heat storage media, and reduce the heat latent of energy storage material this allows the application of phase-change heat to respond to rapid heat load changes and a wider temperature range for paraffin material. since, it causes predominantly conduction heat transfer process during melting and freezing processes in heat exchanger and remains stable operations. 2. crystalline structures are thermally degraded at higher temperature compared to the amorphous structure so it has higher thermal stability than amorphous structure. 3. thermal stability and chemical activity for thermal energy storage 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[34] mahyar silakhori , mohammad sajad naghavi , hendrik simon cornelis metselaar , teuku meurah indra mahlia , hadi fauzi and mohammad mehrali , “accelerated thermal cycling test of microencapsulated paraffin wax/polyaniline made by simple preparation method for solar thermal energy storage”, materials, 6, 1608-1620; doi:10.3390/ma6051608 materials issn 1996-1944, (2013). ا�����ي �� �� �� 2، ا���د����12 ا���ارز � ا���� �� ا���� ا�� ،26 -18 )2016( 26 �دة ا�!� ا������ � # ا����1 0�/���� ا�.��ل ـا�+��ك ا��&اري ���(�م ا��'&ا%$ ا�����ي�� �� � �1�س *ا� � �1�س **4�0 أ� ***ر�5 أ ***�8ار 17�ر ��1 ا�&6� ا?ijkl@ ا?ef=?=cgh@/ ھabc@ ا?<=اد :89 ****،***،* ** @men?ث ا=pq rstj /@ef=?=cgh?ا @ijkl?ا falak_usama@yahoo.com **butn?ا vwوthg?yا : ragad_2015@yahoo.com ***butn?ا vwوthg?yا : �� ا��9 @uارtp?ا @:k[?ا \ur]^ v_ ةbea>?ا bckd]?ا \j bubi?ا bubl?ا @ut>e?=n?ت اk_kf>?م اkhw t_=u(tes) ،\i jf_ وذات @menl? @mubn اد=j vo_ p?ذ @e?ki @wkhjة و=:. @uارtp?ا @:k[l? @wزkr @nsاthj اد=j 8e>dhq sci^ @e?kp?ا @aراb?وا kھtefp^ج وr>^ uev ، ل=pg?ا xece_ v?=q دةkj pvoh koan=q دة ذاتkj @e?ki?ا @eln=>?ا (pvoh) / \e_راkn?ا y>z yj (pw) y>z \j {qk| ج وزنr>q @nsاth>?دة اk>?8 اe>d^ 8^ ، \e_راkn?ا y>~? اريtp?ا xen=h?ا rurih? ، \e_راkn?ا (wpw ل=pg?ا xece_ v?=q دةk>? @alh]j @ew�9 وزاw yj (pvoh)/ v?ا=h?ا sli vوھ y>~?دة اkj)٧٥/٢٥، ٥٠/٥٠،٦٧/٣٣، ١٠٠/٠، ٨٠/٢٠(@nطt?ا �ng?ا @mutام طb]hakq p?وذ ،. @eakaاد ا�=>l? @e?وyت اkn=pa?اء اtfاء ا=a bv sli 8^و)\e_راkn?ا y>zل و=pg?ا xece_ v?=q (�ak>?ا vl�kah?ا ti9>?ام ااb]hakq (dsc) {p^ ele�~^ وفtظ @ te� @uارtp?ل ا=ph?ارة اtv @fدر bubph? @lehc?ا xelp^ 8^ ،@e?k�j )@efkfr?ل اkmhwyارة اtv @fل) در=pg?ا xece_ v?=q اد=>l? ( pvoh) \e_راkn?ا y>zل. و=pg?ا xece_ v?=q دةk>? اريtp?ا xlph?ان ا pvoh ل=ph?ارة اtv @fع درka^أن ار {hn|أ \e_راkn?ا y>z تkukawو (tg) ل pvoh {�lqذ٢٠٩̊ y>~?kq @wرkmj ل يم=ph?ا @f٦٠̊درv?ا=h?ا sli ل. م=pg?ا xece_ v?=q دةkj أن toh^ @lehc?ھ�ه ا pvoh اريtp?ار اtmhayذات ا x? �sاth>?م اkhc?ا {>iد b:pvoh / \e_راkn?ا y>z .صt: @ecm^ امb]hakq p?اري وذtp?ا xen=h?ا @enkr @a8 درا^ biq k>e_و v? .@nst>?ا?<=اد ا pvoh / \e_راkn?ا y>z ?ا buru k>j @e?ki?ا @uارtp?ا @eln=>?ا plh>^ ل=pg?ا xece_ v?=q دةkj ان \e_راkn?ا y>z \j اريtp?ا xen=hkoan=q �ckaو k>?ھ�ه ا {dl]^ارة، وtp?ت اkfدر \j yaق أوk[w sli �en[hl? @lqk: ن=gh? دةk>?ه ا�o? �>9u وھ�ا @uارtp?ا \ur]h?ت اkfدر bci ko^kanا=j te�^ \j دة xn: \j \e_راkn?ا �eli نks k>q @wرkmj ،@fa]cj ارةtv .ل=pg?ا xece_ v?=q دةkj نk_ p?�?و pvoh rurih? ةtens تkwkgjإ koub? vh?ا \e_راkn?دة اk>? {_kأ� @e?ki @uارtv @uارtmhakq x>i?ا s?اري اtp?ا \ur]h?ا bckdr. وذ?th/ pvoh pاthl? �sوف ا?j xg? ��ti^ bci @emen\ ا?o=اء وا?tط=khcl? �>em^ 8^ @qم ا?<thاy>z �s ا?knر_k>s\e ان kmjوj@ ا?khcم ا?< bpa?ت اkecm^ امb]haا �utط \i @q=طtl? @u=m>?ا @n9c?وا @enkdhjyا bp_ امb]hakq)اءt>p?ا {p^ @iz�kq vae[?ا �euز _=رkof (ftir) ل=lpjو ، st^ ذو @q=طt?اre)١٠٠ ٪h2o) ) سkayا?<=اد ا ye>l? ،)�sاth>?م اkhc?وا ، \ee_اtn?ا y>z ، ل=pg?ا xece_ v?=q pw / pvoh) ¢ckhc?ت اtoواظ ، @[ep>?وف اthl? @e?ki @jوkmj) اء=o?ا /@q=طt?س) اkayاد اا=>?kq @wرkmj �sاthj مkhc? pvoh وpw . al-khwarizmi engineering journal al-khwarizmi engineering journal,vol. 12, no. 2, p.p. 100114 (2016) design and simulation of l1-adaptive controller for position control of dc servomotor mohammed ali s. mohammed* amjad j. humaidi** ammar a. al jodah*** *,**,*** department of control and systems engineering / university of technology *email: mohammadalisffah@yahoo.com **email: aaaacontrol2010@yahoo.com ***email: ammar.aljodah@gmail.com (received 17 may 2015; accepted 28 october 2015) abstract this paper presents l1-adaptive controller for controlling uncertain parameters and time-varying unknown parameters to control the position of a dc servomotor. for the purpose of comparison, the effectiveness of l1-adaptive controller for position control of studied servomotor has been examined and compared with another adaptive controller; model reference adaptive controller (mrac). robustness of both l1-adaptive controller and model reference adaptive controller to different input reference signals and different structures of uncertainty were studied. three different types of input signals are taken into account; ramp, step and sinusoidal. the l1-adaptive controller ensured uniformly bounded transient and asymptotic tracking for both system's input and output signals, simultaneously with asymptotic tracking. simulations of a dc servomotor with time-varying friction and disturbance are presented to verify the theoretical findings. keywords: l1-adaptive controller, dc servomotor position control. 1. introduction research in adaptive control was motivated by the design of autopilots for highly agile aircraft that need to operate at wide range of speeds and altitudes, experiencing large parametric variations. in the early 1950s, adaptive control was conceived and proposed as a technology for automatically adjusting the controller parameters in the face of changing aircraft dynamics [1, 2]. the initial results in adaptive control were inspired by system identification, which led to an architecture consisting of an online parameter estimator combined with automatic control design [3]. two architectures of adaptive control emerged: the direct method, where only controller parameters were estimated, and the indirect method, where process parameters were estimated and the controller parameters were obtained using some design procedure. to achieve identifiability, it was necessary to introduce a condition of persistency of excitation in order to guarantee that the parameter estimates converge. the progress in systems theory led to fundamental theory for development of stable adaptive control architectures [4-6]. the basic idea of all the modifications was to limit the gain of the adaptation loop and to eliminate its integral action. examples of these modifications are the σmodification and the e-modification. all these modifications attempted to provide a solution to the problem of parameter drift [6, 7]. however, despite the success of such techniques in many applications, they hold some drawbacks. for instance, adaptive controllers rely on the need of a persistency in parameter excitation before convergence which may lead to a bad transient behavior. a regressor is often required, involving mailto:mohammadalisffah@yahoo.com mailto:aaaacontrol2010@yahoo.com mailto:ammar.aljodah@gmail.com mohammed ali s. mohammed al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 100114 (2016) 101 with it a large parameter vector to be estimated. moreover, a large adaptation gain may have undesirable effects, with the risk of parameter divergence. all of the arguments brought against adaptive schemes reveal that despite their numerous advantages, these controllers hold some drawbacks. for the sake of clarity, one can summarize some of them here [7, 8, 9]: 1. a wide range of such controllers exhibit undesirable frequency characteristics and are often used with restrictive assumptions. it has been shown that the sinusoidal reference inputs at certain frequencies and/or sinusoidal output disturbances at any frequency will significantly increase the adaptation gain which will destabilize the control system. 2. the need for the persistency in excitation can lead to a bad transient behavior. 3. an increase in the adaptation gain drives the closed-loop system closer to instability, while a small gain would slow down the convergence. any parameter vector to be adapted must be adequately initialized, and this choice would depend on the specific configuration of the system. recently, a new variant of adaptive control has been developed named as l1-adaptive control. this version of adaptive control is utilizing fast and robust adaptation; it permits a transient analysis even for time varying uncertainties and is capable of handling constraints. the l1-adaptive control is presented as an adaptive approach for nonlinear time varying systems in the presence of state constraints [10]. 2. problem formulation the following class of systems will be considered [7, 11, 12]; 𝑥 𝑡 = 𝐴𝑚𝑥 𝑡 + 𝑏 (𝜔 𝑢 𝑡 + 𝜃t 𝑡 𝑥 𝑡 𝜎 𝑡 ) 𝑦 𝑡 = 𝑐t𝑥 𝑡 …(1) where 𝑥 𝑡 ∈ ℝ𝑛 is the system measured state vector; 𝑢 𝑡 ∈ ℝ is the control input, 𝑦 𝑡 ∈ ℝ is the regulated output; 𝑏, 𝑐 ∈ ℝ𝑛 are known constant vectors; 𝐴𝑚 is a known hurwitz 𝑛 × 𝑛 matrix (all its eigenvalues have negative real values that specifying the desired closed-loop dynamics); 𝜔 ∈ ℝ is an unknown constant (with known sign); 𝜃 𝑡 ∈ ℝ𝑛 is a vector of timevarying unknown parameters; and 𝜎 𝑡 ∈ ℝ models input disturbances. the objective of the desired controller is to ensure that 𝑦 𝑡 tracks a given bounded piecewise-continuous reference signal 𝑟 𝑡 with quantifiable performance bounds using full-state feedback adaptive controller based on the following assumptions [7, 11-14] assumption (i): uniform boundedness of unknown parameters letting 𝜃 𝑡 ∈ θ, 𝜎 𝑡 ≤ ∆0 , ∀𝑡 ≥ 0. …(2) where θ is a convex compact set, and ∆0 ∈ ℝ+ is a conservative bound of 𝜎 𝑡 [7, 11-14]. assumption (ii): uniform boundedness of rate of parameters' variations this assumes that 𝜃 𝑡 and 𝜎 𝑡 have to be continuously differentiable with uniformly bounded derivatives [7, 12, 13]: 𝜃 𝑡 ≤ 𝑑𝜃 < ∞, 𝜎 𝑡 ≤ 𝑑𝜎 < ∞, ∀𝑡 ≥ 0. ...(3) assumption (iii): uncertain system input gain is partially known this assumes that 𝜔 ∈ ω0 ≜ 𝜔𝑙0 , 𝜔𝑢0 , …(4) where 0 < 𝜔𝑙0 < 𝜔𝑢0 are given known lower and upper bounds on 𝜔. 3. l1-adaptive control architecture in what follows, the elements of l1-adaptive controller will be considered. the controller comprises three main parts; state predictor, adaptation law and control law [7, 11, 14]. 3.1. state predictor let us consider the following state predictor: 𝑥 𝑡 = 𝐴𝑚𝑥 𝑡 + 𝑏 𝜔 𝑡 𝑢 𝑡 + 𝜃 t 𝑡 𝑥 𝑡 + 𝜎𝑡, 𝑥0=𝑥0 𝑦 𝑡 = 𝑐t𝑥 𝑡 …(5) which has the same structure as the system in (1); the only difference is that the unknown parameters 𝜔, 𝜃 𝑡 , and 𝜎 𝑡 are replaced by their adaptive estimates 𝜔 𝑡 , 𝜃 𝑡 , and 𝜎 𝑡 , respectively. 3.2. adaptation laws the adaptive process is governed by the following projection-based adaptation laws: mohammed ali s. mohammed al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 100114 (2016) 102 𝜃 𝑡 = г proj 𝜃 𝑡 , −𝑥 t 𝑡 𝑃𝑏𝑥 𝑡 , 𝜃 0 = 𝜃 0 , 𝜎 𝑡 = г proj 𝜎 𝑡 , −𝑥 t 𝑡 𝑃𝑏 , 𝜎 0 = 𝜎 0, 𝜔 𝑡 = г proj 𝜔 𝑡 , −𝑥 t 𝑡 𝑃𝑏𝑢 𝑡 , 𝜔 0 = 𝜔 0 …(6) where 𝑥 𝑡 ≜ 𝑥 𝑡 − 𝑥 𝑡 , г ∈ ℝ+ is the adaptation rate and 𝑃 = 𝑃t > 0 is the solution of the algebraic lyapunov equation 𝐴𝑚 t 𝑃 + 𝑃𝐴𝑚 = −𝑄 for arbitrary 𝑄 = 𝑄t > 0. in the implementation of the projection operator, one can use the compact set θ as given in assumption (i), while one can replace ∆0 and ω0 by ∆ and ω ≜ 𝜔𝑙0, 𝜔𝑢0 such that [7, 14] ∆0< ∆, 0 < 𝜔𝑙 < 𝜔𝑙0 < 𝜔𝑢 < 𝜔𝑢0 …(7) 3.3. control law the control signal is generated as the output of the following (feedback) system: 𝑢 𝑠 = −𝑘𝐷 𝑠 𝜂 𝑠 − 𝑘 g 𝑟 𝑠 , …(8) where 𝑟 𝑠 and 𝜂 𝑠 are the laplace transforms of 𝑟(𝑡 ) and 𝜂 𝑡 ≜ 𝜔 𝑡 𝑢 𝑡 + 𝜃 t 𝑡 𝒙 𝑡 + 𝜎 𝑡 , respectively; 𝑘 g ≜ −1/𝑐t𝐴𝑚 −1𝑏; and 𝑘 > 0 and 𝐷 𝑠 are a feedback gain and a strictly proper transfer function leading to a strictly proper stable 𝐶 𝑠 ≜ 𝜔𝑘𝐷 𝑠 1+𝜔𝑘𝐷 𝑠 ∀𝜔 ∈ ω0 …(9) with dc gain c(0) = 1. one simple choice is 𝐷 𝑠 = 1/𝑠, which yields a first-order strictly proper 𝐶 𝑠 of the form [7, 11] 𝐶 𝑠 = 𝜔𝑘 𝑠+𝜔𝑘 …(10) letting 𝜃 ∈ θ [7, 11-14], 𝐿 ≜ max 𝜃∈θ 𝜃 1 𝐻 𝑠 ≜ 𝑠𝕀 − 𝐴𝑚 −1𝑏 𝐺 𝑠 ≜ 𝐻 𝑠 1 − 𝐶 𝑠 …(11) the l1-adaptive controller is defined via (1), (2), (4), subjected to the following l1-norm condition: 𝐺 𝑠 1l 𝐿 ≤ 1 …(12) the l1-adaptive control architecture with its main elements is represented in figure (1). in the case of constant 𝜃 𝑡 , the l1-norm condition can be simplified. for the specific choice of 𝐷 𝑠 = 1/ 𝑠, it is reduced to; 𝐴 g ≜ 𝐴𝑚 + 𝑏𝜃t 𝑏𝜔 −𝑘𝜃t −𝑘𝜔 , …(13) 𝐴 g being hurwitz which all its eigenvalues have negative real values for all 𝜃 ∈ θ and 𝜔 ∈ ω0 [7, 11]. 3.4. projection operator consider a convex, compact set with a smooth boundary given by [7, 9] ω𝑐 ≜ 𝜃 ∈ ℝ𝑛 |𝑓(𝜃) ≤ 𝑐 0 ≤ 𝑐 ≤ 1, …(14) where f : ℝ𝑛 → ℝ is the following smooth convex function: 𝑓 𝜃 = 𝜃𝑇𝜃−𝜃𝑚𝑎𝑥 2 𝜀𝜃 𝜃𝑚𝑎𝑥 2 …(15) where 0 < 𝜀𝜃 ≤ 1 and 𝜃𝑚𝑎𝑥 is the norm bound imposed on the parameter vector 𝜃, and 𝜀𝜃 denotes the convergence tolerance of our choice. let the true value of the parameter 𝜃, denoted by 𝜃∗ belong to ω𝑜 , i.e. 𝜃∗ ∈ ω𝑜 . the special structure of the function 𝑓 should be interpreted as: if one solves 𝑓 𝜃 ≤ 1, which defines the boundaries of the outer set, then one can get that 𝜃𝑇𝜃 ≤ 1 + 𝜀𝜃 𝜃𝑚𝑎𝑥 2 . 𝜀𝜃 specifies the maximum tolerance the adaptive parameter is allowed to exceed compared to its maximum conservative value. the projection operator is defined as: 𝑃𝑟𝑜𝑗 𝜃, 𝑦 ≜ 𝑦 𝑖𝑓 𝑓 𝜃 < 0, 𝑦 𝑖𝑓 𝑓 𝜃 ≥ 0 𝑎𝑛𝑑 ∇𝑓𝑇𝑦 ≤ 0, 𝑦 − ∇𝑓 ∇𝑓 ∇𝑓𝑇 ∇𝑓 , 𝑦 𝑖𝑓 𝑓 𝜃 ≥ 0 𝑎𝑛𝑑 ∇𝑓𝑇𝑦 > 0, mohammed ali s. mohammed al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 100114 (2016) 103 fig. 1. closed-loop l1-adaptive system [4]. 4. modeling of dc motor in the present work, a separately excited dc motor was considered, as shown in figure (2), fig. 2. a separately excited dc motor model. the equations describing the dynamic behavior of the dc motor are given by [15]: 𝑑𝑖𝑎 𝑡 𝑑𝑡 = 1 𝐿𝑎 𝑒𝑎 𝑡 − 𝑅𝑎 𝐿𝑎 𝑖𝑎 𝑡 − 1 𝐿𝑎 𝑒𝑏 𝑡 …(17) 𝑇𝑚 𝑡 = 𝐾𝑖 𝑖𝑎 𝑡 …(18) 𝑒𝑏 𝑡 = 𝐾𝑏 𝑑𝜃𝑚 𝑡 𝑑𝑡 = 𝐾𝑏𝜔𝑚 𝑡 = 𝐾𝑏𝜃 𝑚 (𝑡) …(19) 𝑇 𝑡 = 𝐽 𝑑𝜔 (𝑡) 𝑑𝑡 + 𝐵 𝜔𝑚 𝑡 + 𝑇1 𝑡 = 𝐾𝑡 𝑖𝑎 𝑡 …(20) where the 𝑇1 𝑡 accounts for nonlinear disturbances which includes the nonlinear friction, torque disturbances and other nonlinearities of the system, 𝑇1 𝑡 = 𝑘𝑣𝜃𝑚 𝑡 + 𝑇𝑓 𝜃𝑚 𝑡 + 𝑇𝐿 𝑡 …(21) 𝑇𝑓 𝜃𝑚 𝑡 = 𝐹𝑠 − 𝐹𝑐 𝑠𝑔𝑛 𝜃𝑚 𝑡 𝑒− 𝜃 𝑚 𝑡 𝜃 𝑠 2 +𝐹𝑐𝑠𝑔𝑛 𝜃𝑚 𝑡 …(22) where, 𝜔𝑚 𝑡 is the rotational speed, 𝜃𝑚 is the angular displacement, 𝑖𝑎 𝑡 armature circuit current, 𝑇𝑓 𝑡 is the friction torque, 𝑇𝐿 𝑡 is the load torque, 𝑅𝑎 armature circuit resistance, 𝐵 coefficient of viscous-friction, 𝐾𝑡 torque coefficient, 𝐽 moment of inertia, and 𝐿𝑎 armature circuit inductance, 𝑘𝑣 is the viscous friction coefficient, 𝐹𝑠 is the stribeck friction constant, 𝐹𝑐 is the colomb friction level, 𝑠𝑔𝑛(∙) is the signum function, and 𝜃 𝑠 is the stribeck angular constant velocity. for 𝐿𝑎 ≪ 𝑅𝑎 𝐿𝑎 can be ignored so the model in equations (17) to (20) can be simplified to the following: (for simplicity we will omit the t and s parameters from the equations) 0 = 𝑒𝑎 − 𝑅𝑎 𝑖𝑎 − 𝐾𝑏𝜃 𝑚 …(23) 𝑖𝑎 = 1 𝑅𝑎 𝑒𝑎 − 𝐾𝑏 𝑅𝑎 𝜃 𝑚 …(24) 𝜃 𝑚 = − 𝐵 𝐽 𝜃 𝑚 + 𝐾𝑡 𝐽 𝑖𝑎 − 1 𝐽 𝑇1 …(25) by substituting equation (24) into equation (25) this will lead to: 𝜃 𝑚 = − 𝑅𝑎𝐵+𝐾𝑡𝐾𝑏 𝐽𝑅𝑎 𝜃 𝑚 + 𝐾𝑡 𝐽𝑅𝑎 𝑒𝑎 − 𝑘𝑣 𝐽 𝜃 𝑚 − 1 𝐽 𝑇𝑓 𝜃 𝑚 + 𝑇𝐿 …(26) let 𝑥1 = 𝜃𝑚 and 𝑥2 = 𝜃 𝑚 , the state space form can be written in the following form; 𝑥 1 𝑥 2 = 0 1 0 − 𝑅𝑎𝐵+𝐾𝑡𝐾𝑏 𝐽𝑅𝑎 𝑥1 𝑥2 + 0 1 𝐾𝑡 𝐽𝑅𝑎 𝑢 − 𝑘𝑣𝐽𝜃𝑚−1𝐽𝑇𝑓𝜃𝑚+𝑇𝐿 …(27) 𝑦 = 1 0 𝑥1 𝑥2 if equation (27) had been compared with equation (1), 𝑥 𝑡 = 𝐴𝑚𝑥 𝑡 + 𝑏 𝜔 𝑢 𝑡 + 𝜃t 𝑡 𝑥 𝑡 + 𝜎𝑡 mohammed ali s. mohammed al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 100114 (2016) 104 by induction, one may easily find that 𝜎 𝑡 = − 1 𝐽 𝑇𝑓 𝜃 𝑚 + 𝑇𝐿 , 𝜃t = 0 −𝑘𝑣 𝐽 , 𝜔 = 𝐾𝑡 𝐽𝑅𝑎 , 𝑏 = 0 1 𝑇 and 𝑐 = 1 0 where 𝑨𝑚 = 𝑨 − 𝑏𝐾𝑚 and 𝐾𝑚 = 𝑘1 𝑘2 is the state feedback gain necessary for making the state matrix 𝑨 being hurwitz which all its eigenvalues have negative real values. 5. controllability condition poleplacement the requirement for applying pole placement is that the system must be completely state controllable. the state and input matrix of dc motor are given, respectively, 𝑨 = 0 1 0 − 𝑅𝑎𝐵+𝐾𝑡𝐾𝑏 𝐽𝑅𝑎 and 𝒃 = 0 1 𝑇 the controllability matrix is given by [16] 𝑴 = 𝒃 𝑨 𝒃 = 0 1 1 − 𝑅𝑎𝐵+𝐾𝑡𝐾𝑏 𝐽 𝑅𝑎 …(28) the controllability matrix is given by [16] it is evident that the rank of controllability matrix is equal to 2, which is equal to the system order. therefore, the system is completely controllable and the pole placement could be applied. numerically, if the system has the following values in table (1), the eigenvalues for this system is 𝑠1 = 0 and 𝑠2 = −59.202 since the system is completely state controllable, one can arbitrary select the desired poles to be 𝑠1 = −40 and 𝑠2 = −50 the elements of state feedback gain 𝐾𝑚 which performs pole placement requirements is given by 𝑲𝑚 = 𝑘1 𝑘2 = 2000 −30.8 this transformation is achieved by 𝑨𝑚 = 𝑨 − 𝑏𝐾𝑚 = 0 1 −2000 −90 table 1, system model parameters for dc servomotor. parameter value 𝑅𝑎 5 𝛀 𝐵 0.136 n.m.s 𝐾𝑡 0.245 n.m/a 𝐾𝑏 0.245 v.s/rad 𝐽 0.0025 kg.m2/s 2 𝐿𝑎 0.01 6. simulink modeling of adaptive controller for dc-servo motor based on equation (27), complete simulink implementation adaptive controller for dc servomotor is depicted in figure (3). the overall simulink model consists of different blocks that combines together to achieve a suitable simulation of single axis positioning table. signals block contains the main reference signals and for the different types of inputs. it also comprises the uncertainties resulting from load and friction forces. the elements of the signals block can be illustrated in figure (4). mohammed ali s. mohammed al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 100114 (2016) 105 fig. 3. overall simulink blocks dc servomotor fig. 4. signals block. the contents of l1-adaptive controller block are simulated in figure (5). fig. 5. adaptive controller block contents mohammed ali s. mohammed al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 100114 (2016) 106 the simulink block shown in figure (6) gives the components which simulate the model of the single axis positioning table. fig. 6. modeling of single axis positioning table. adaptation block implements the adaptation techniques used in the present work. it also includes projection block to perform the task of projection operator. this operator used to keep the system parameters bound in a known defined region. the contents of the adaptation block are shown in figure (7). fig. 7. simulink simulation of adaptation algorithm with projection operator. the elements of predictor block responsible for predicting both parameters and errors are depicted in figure (8). fig. 8. contents of predictor block. mohammed ali s. mohammed al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 100114 (2016) 107 7. simulated results for simulation purposes, two different architectures of adaptive control were taken: l1adaptive control and mrac. three types of inputs: ramp, sinusoidal, and step inputs were used to compare between the two architectures. in design of l1-adaptive controller, the filter of the controller is selected as 𝐷 𝑠 = 𝐾 𝑠 and the parameter of gain 𝐾 and adaptation gain γ have been set to 𝐾 = 100 and γ = 104 using trial-anderror procedure. the system model parameters are listed in table (1) above. the uncertainty 𝜎 𝑡 considered in this system has the following form, 𝜎 𝑡 = − 1 𝐽 𝑇𝑓 𝜃 𝑚 𝑡 + 𝑇𝐿 𝑡 also, 𝜔 = 𝐾𝑡 𝐽𝑅𝑎 , 𝜃t = 0 −𝑘𝑣 𝐽 substituting the values of friction model parameters, the uncertainty bound and the value of parameter 𝜔 can be given by 𝜎 𝑡 ∈ ∆ = [−1.2, 2.1996] (n.mm), 𝜔 = 19.6 (n.s 2 /kg.mm.a), 𝜃t = 0 −0.8 to show the robustness of the l1-adaptive control, four cases of different values of uncertainties and disturbances were listed in table (2), the following normalized friction parameters have been considered for simulation; 𝑘𝑣 = 0.002 n.s/mm, 𝐹𝑐 = 0.0002 n.mm, 𝐹𝑠 = 0.003 n.mm, 𝜃 𝑠= 0.0002 rad/s table 2, cases for disturbance amplitude and frequency. parameter case 1 case 2 case 3 case 4 𝜎 𝑡 0.002 sin 𝑡 + 𝑇𝑓 𝜃 𝑚 𝑡 sin 𝑡 + 𝑇𝑓 𝜃 𝑚 𝑡 0.002 sin 10𝑡 + 𝑇𝑓 𝜃 𝑚 𝑡 sin 10𝑡 + 𝑇𝑓 𝜃 𝑚 𝑡 the following normalized friction parameters have been considered for simulation; 𝑘𝑣 = 0.002 n.s/mm, 𝐹𝑐 = 0.0002 n.mm, 𝐹𝑠 = 0.003 n.mm, 𝜃 𝑠= 0.0002 rad/s 7.1. results based on ramp input for case(1)-case(4) of table (2), the position responses and the control signals are shown in figures (9)-(12). the figures show that l1-adaptive controller gives a better tracking performance for the ramp input rather than mrac. moreover, the control signals based on mrac suffer from distortion along tracking period. the steady-state errors for l1-adaptive controller and mrac responses are shown in table (3). 7.2. results based on step input it is interesting to examine the effectiveness of both controllers as the system is subjected to a unit step. for the present scenarios, a step input of 0.005 rad height is fed to the system. this step input is inverted after 1.5 sec. such that a square wave input is repeated for every 3 sec. the performance of both controllers for the situations listed in table (2) will again considered here. the position responses and the control signals based on the four cases are shown in figures (13)-(16). one can easily see that the response based on l1adaptive controller could give better performance in terms of transient characteristics than those based on mrac. table (4) lists the summary of steady state errors resulting from both controllers for all four cases. it can be concluded that steady state error based on l1-adaptive controller for all considered cases has nearly zero value. on the other hand mrac gives considerably large steady state error for all studied cases. 7.3. results based on sinusoidal input in what follows, the simulation is made for sinusoidal type of input. table (2) is considered for the uncertainty structures. the procedure followed earlier will be repeated here for all cases of table (2). it is clear from the figures (17)-(20) that l1-adaptive controller is better than mrac in terms of position tracking. again the control signals based on mrac suffer from distortion along tracking period. it can be seen from table (5) that for all cases the steady state errors based on l1-adaptive controller are lower than those based on mrac. mohammed ali s. mohammed al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 100114 (2016) 108 table 3, steady-state errors for different cases of ramp input. table 4, steady-state errors for different cases of step input. (a) ramp responses (b) control signals fig. 9. transient responses and control signals based on l1-adaptive controller and mrac for ramp input (case 1). (a) ramp responses (b) control signals fig. 10. transient responses and control signals based on l1-adaptive controller and mrac for ramp input (case 2). steady state error (𝒓𝒂𝒅) case 1 case 2 case 3 case 4 l1-controller 0.0086 0.0065 0.0089 0.108 mrac 0.2248 0.2068 0.2247 0.2128 steady state error (𝒓𝒂𝒅) case 1 case 2 case 3 case 4 l1-controller 0.01 0.0073 0.01 0.0071 mrac 0.23 0.2058 0.23 0.2129 mohammed ali s. mohammed al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 100114 (2016) 109 (a) ramp responses (b) control signals fig. 11. transient responses and control signals based on l1-adaptive controller and mrac for ramp input (case 3). (a) ramp responses (b) control signals fig. 12. transient responses and control signals based on l1-adaptive controller and mrac for ramp input (case 4). (a) step responses (b) control signals fig. 13. transient responses and control signals based on l1-adaptive controller and mrac for step input (case 1). mohammed ali s. mohammed al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 100114 (2016) 110 (a) step responses (b) control signals fig. 14. transient responses and control signals based on l1-adaptive controller and mrac for step input (case 2). (a) step responses (b) control signals fig.15. transient responses and control signals based on l1-adaptive controller and mrac for step input (case 3). (a) step responses (b) control signals fig. 16. transient responses and control signals based on l1-adaptive controller and mrac for step input (case 4) mohammed ali s. mohammed al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 100114 (2016) 111 (a) sinusoidal responses (b) control signals fig. 17. transient responses and control signals based on l1-adaptive controller and mrac for sinusoidal input (case 1). (a) sinusoidal responses (b) control signals fig. 18. transient responses and control signals based on l1-adaptive controller and mrac for sinusoidal input (case 2). (a) sinusoidal responses (b) control signals fig. 19. transient responses and control signals based on l1-adaptive controller and mrac for sinusoidal input (case 3). mohammed ali s. mohammed al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 100114 (2016) 112 (a) sinusoidal responses (b) control signals fig. 20. transient responses and control signals based on l1-adaptive controller and mrac for sinusoidal input (case 4). table 5, steady-state errors for different cases of sinusoidal input. 8. conclusions 1. for ramp exciting input, the results showed that l1-adaptive controller has better tracking performance than mrac. for some uncertainty structure, the mrac control signals give distorted response. 2. for step exciting input, l1-adaptive controller could track and gives better transient characteristics than mrac. 3. for sinusoidal inputs, l1-adaptive controller gives satisfactory tracking performance for all structures of uncertainties. however, for some uncertainty structure, the mrac control signals give distorted response. 4. for all types of inputs and for all structures of uncertainties, the l1-adaptive controller gives less steady state errors (nearly zero) than the mrac. 9. references [1] mohammed ali s. mohammed, design and simulation of l1-adaptive controller for xy position table, m.sc. thesis, university of technology, computer and control systems department, mechatronics engineering, nov. 2014. 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[14] c. cao and n. hovakimyan, "stability margins of l1-adaptive controller: part ii", american control conference, new york city, usa, pp. 3931–3936, july 2007. [15] ahmed m. k. and ali m. y., "experimental setup and robust servo dc motor position control based on gain schedule sliding mode controller", research journal of applied sciences, engineering and technology, maxwell scientific organization, issn 2040–7467, pp. 1320– 1327, may 2012. [16] katsuhiko ogata, modern control engineering, 5th edition, prentice hall, new jersey, usa, 2010. (2016) 100114، صفحت 2، العذد12دالمجلجلة الخوارزمي الهندسية م محمد علي سفاح محمد 114 الموضعيت لمؤازراث محرك التيار المستمر للسيطرة l1 ومحاكاة مسيطر تكيفي نوع تصميم *** عمار عبذ الحسين ** امجذ جليل حميذي* محمذ علي سفاح محمذ اىداٍؼت اىخنْوىوخَت / قسٌ هْذست اىسَطشة واىْظٌ ***،**،* mohammadalisffah@yahoo.com :اىبشٍذ االىنخشوٌّ* aaaacontrol2010@yahoo.com :اىبشٍذ االىنخشوٌّ** ammar.aljodah@gmail.com :اىبشٍذ االىنخشوٌّ*** الخالصت ىَؤاصس رو حَاس ٍسخَش فٌ حاىت وخود ٍؼيَاث غَش اىيسَطشة ػيي اىَوضغ l1-adaptive controller))ٍؼشض هزا اىؼَو اىَسَطش اىَخنَف ّوع . ٍؤمذة اىقََت ومزىل فٌ حاه وخود ٍؼيَاث حخغَش صٍَْاً بشنو غَش ٍؼيوً ٓ ٍغ اداء اىَسَطش اىَخنَف راث االَّورج ئاىخَاس اىَسخَش فقذ حٌ ٍقاسّت ادا ًاىَوضؼَت ىيَحشك رٌٍ فؼاىَت اىَسَطش اىَقخشذ ىيسَطشة وىغشض حق . ٓىْفس ٍؤاصسىو( mrac)اىَشخؼٌ ، اشاسة خطوٍت)حٌ دساست ٍذى قابيَت مال اىَسَطَشٍِ ىيحفاظ ػيي االداء اىَطيوب ٍغ حغَش ٍؼيَاث اىَْظوٍت ٍغ اػطاء اشناه ٍخخيفت الشاسة االدخاه .(اشاسة خَبَت واشاسة ٍائيت ٍخابؼت ٍُضَِ ٍخابؼت اّخقاىَت ٍحذدة ىَخخيف اشناه اشاساث االدخاه ومزىل ٍضٌ l1-adaptive controller))قذ اوضحج اىْخائح اُ اىَسَطش ّوع اىخَثَو باسخخذاً اىحاسبت ىيَْظوٍت ححج اششاف مال اىَسَطشٍِ ٍغ وخود اضطشاب وخصائص احخناك ٍؼَْت واثبخج اىْخائح صحت اىخحيَالث . ٍسخقشة . اىْظشٍت mailto:mohammadalisffah@yahoo.com mailto:aaaacontrol2010@yahoo.com mailto:ammar.aljodah@gmail.com al-khwarizmi engineering journal al-khwarizmi engineering journal,vol. 12, no. 2, p.p. 3444 (2016) using activated carbon developed from iraqi date palm seeds as permeable reactive barrier for remediation of groundwater contaminated with copper ziad t. abd ali department of environmental engineering / college of engineering/ university of baghdad e-mail: z.teach2000@yahoo.com (received 6 september 2015; accepted 10 january 2016) abstract the possibility of using activated carbon developed from date palm seeds wastes as a permeable reactive barrier (prb) to remove copper from polluted shallow groundwater was investigated. the activated carbon has been developed from date palm seeds by dehydrating methods using concentrated sulfuric acid. batch tests were performed to characterize the equilibrium sorption properties of new activated carbon in copper-containing aqueous solutions, while the sandy soil (aquifer) was assumed to be inert. under the studied conditions, the langmuir isotherm model gives a better fit for the sorption data of copper by activated carbon than other models. at a pilot scale, one-dimensional column experiments were performed, and an integrated model based on the solution of an advection-reaction-dispersion mass balance equation, using comsol multiphysics 3.5a software which is based on finite element method, was developed to study the space and time concentration of copper within groundwater. experimental and numerical results proved that the prb represents a potential role in the restriction of the copper plume migration. also, these results showed that the greater thickness of prb results in a better treatment of copper and that the barrier starts to saturate with contaminant as a function of the travel time. however, a good agreement between the predicted (theoretical) and experimental results with rmse not exceeded the 0.08 proved these methods are effective and efficient tools in description of copper transport phenomena adopted here. keywords: date palm seeds, activated carbon, copper, permeable reactive barrier, groundwater, transport. 1. introduction the pollution of groundwater by pollutants has been considered since the industrial revolution [1]. copper, as well as other heavy metals, is released into the environment in a number of different ways and it finds the way to get into the water-streams and groundwater thus make environmental pollution that presents threat to plants, animals, and humans, therefore serious of complex problems can be happen [2]. "groundwater, which is water found beneath the surface of the ground and seeped down from the surface by migrating through the soil matrix and spaces in geologic formations, is generally more reliable for use than surface water" [3]. historically, the pump-and-treat technique was the most common technology used for remediation of groundwater. this technique is costly, difficult, and ineffective most of the time in removing enough pollution to restore the groundwater to drinking water standards in acceptable time frames. the inability to extract pollutants from the subsurface due to hydrogeologic factors and trapped residual contaminant mass was the primary reason for the failure of pump and treat. accordingly, the other method used to remediate groundwater contaminated with different types of contaminants was permeable reactive barrier (prb) technology. it is found to be more costeffective than pump and treat and has demonstrated the potential to diminish the spread of contaminants [4]. "activated carbon has versatility and wide range of applications and it has been proven to be an effective adsorbent for the removal of a wide variety of organic and ziad t. abd ali al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 3444(2016) 35 inorganic pollutants from different media. therefore, production of low-cost activated carbon becomes the aim of many researchers since the commercial activated carbon is still very expensive" [5]. the worthy aspects of this study are the development of new activated carbon from date palm seeds as an inexpensive and efficient reactive material and the ability of using of this material in prbs for the removal of copper from polluted groundwater. 2. description of sorption data for the description of sorption data five isotherm models were used. a summary of these models was presented by "hamdaoui and naffrechoux" [6] as follows:  the langmuir model can be expressed as in equation (1): 𝑞𝑒 = 𝑞𝑚 𝑏𝐶𝑒 1+𝑏𝐶𝑒 …(1) where qm is the maximum adsorption capacity (mg/g), b (l/mg) is the constant related to the free energy of adsorption, ce (mg/l) is the equilibrium concentration of the solute in the bulk solution, and qe (mg/g) is the amount of solute adsorbed per unit weight of adsorbent at equilibrium.  the freundlich model is given by equation (2): 𝑞𝑒 = 𝐾𝐹𝐶𝑒 1 𝑛 …(2) where n is an empirical coefficient indicative of the intensity of the adsorption and kf is the freundlich sorption coefficient.  the elovich model is based on a kinetic principle assuming that the adsorption process increase with sites of adsorption. it can be written as in equation (3): 𝑞𝑒 𝑞𝑚 = 𝐾𝐸𝐶𝑒exp⁡ − 𝑞𝑒 𝑞𝑚 …(3) where ke is the elovich equilibrium constant (l/mg), and qm is the elovich maximum adsorption capacity (mg/g)  the temkin model assumes that with coverage the heat of adsorption of all the molecules in the layer decreases linearly because of the interactions of adsorbent–adsorbate. this model is represented by equation (4): 𝜃 = 𝑅𝑇 ∆𝑄 𝑙𝑛𝐾𝑜𝐶𝑒 ...(4) where ko is the temkin equilibrium constant (l/mg), ∆q is the variation of adsorption energy (kj mol −1 ), t is the temperature (k), r is the universal gas constant (kj mol −1 k −1 ), and θ (=qe/qm) is the fractional coverage.  the kiselev model can be written as in equation (5): 𝑘1𝐶𝑒 = 𝜃 1−𝜃 1+𝑘𝑛𝜃 …(5) where k1 is the kiselev equilibrium constant (l/mg), θ (=qe/qm) is the fractional coverage, and kn is the constant of complex formation between adsorbed molecules. 3. experimental work 3.1. materials iraqi date seeds were used to prepare the activated carbon; it washed with hot distilled water to remove the dust and other foreign materials, dried in oven at 200◦c for 24 h. "the dried seeds were milled, sieved to the particle size of 1–0.6 mm and stored in airtight container for carbonization. 2 kg of dried date palm seeds were added in small portion to h2so4 (98%, 2 l) during 5 h followed by boiling for 20 h in a fume hood. cool in ice bath and the reaction mixture was poured onto cold water (5 l) and filtered. the obtained carbon was dried in an open oven at 120 ◦c for 24 h followed by immersed in 5% nahco3 (4 l) to remove any remaining acid and then filter" [7]. the produced carbon was then washed with distilled water until ph of the activated carbon reached 6, dried at 105 ◦c for 24 h and sieved to the particle size 1-0.6 mm (porosity = 0.45) and kept in a airtight container until used. the sandy soil was used as aquifer in the conducted experiments. this soil had a particle size distribution ranged from 63 μm to 0.71 mm (porosity = 0.41) with an effective grain size, d10, of 110 μm, a median grain size, d50, of 180μm and a uniformity coefficient, cu= d60/d10, of 1.73. the salt of cu(n03)2 (manufactured by bdh, england) was used in the preparation of the copper stock solution by dissolving it at a known concentration in distilled water. the solutions used for the study were obtained by dilution of the stock solution to the required concentration. the initial ph of each of the solutions was adjusted by the addition of hno3 or naoh solution. the initial concentrations of the copper, and the corresponding concentrations after fixed the time periods, were measured by an atomic adsorption spectrophotometer (aas) (shimadzu, japan). ziad t. abd ali al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 3444(2016) 36 3.2. batch experiments these tests are carried out to specify the best conditions of contact time, initial ph of the solution, initial copper concentration, dosage of activated carbon and agitation speed. series of 250 ml flasks are employed and each flask is filled with 50 ml of copper solution which has initial concentration of 50 mg/l. about 0.5 g/50 ml of activated carbon was added into different flasks and these flasks were kept stirred in the high-speed orbital shaker at 200 rpm for 90 min. a fixed volume (20 ml) of the solution was withdrawn from each flask. this withdrawn solution was filtered to separate the activated carbon and a fixed volume (10 ml) of the clear solution was pipetted out for the concentration determination of copper still present in solution. the measurements were carried out using atomic adsorption spectrophotometer (aas) (shimadzu, japan). however, the adsorbed concentration of copper on the activated carbon was obtained by a mass balance. kinetic studies were investigated with different values of ph (3, 4, 5, 6 and 7), different values of initial concentration of copper (50, 60, 70, 80 and 90 mg/l), amounts of activated carbon dosage (0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8 and 1 g/50 ml) and finally values of agitation speed (0, 50, 100, 150, 200 and 250 rpm). from the best experimental results, the amount of copper retained in the activated carbon phase, qe, was calculated using equation (6) [8]: 𝑞𝑒 = 𝐶𝑜 − 𝐶𝑒 𝑉 𝑚 …(6) where co and ce are the initial and equilibrium concentrations of copper in the solution (mg/l), v is the volume of solution in the flask (l), and m is the mass of adsorbent material (activated carbon) in the flask (g). 3.3. continuous experiments the reactor setup used in the present study was constructed of perspex column having height and diameter equal to 50 and 5 cm, respectively. this reactor was schematically shown in fig.1. the column is equipped with four sampling ports at a distance of 10 cm (port 1), 20 cm (port 2), 25 cm (port 3), 35 cm (port 4), from the bottom. these ports along the length of the column were assembled of stainless steel fittings which blocked with viton stoppers (doit, dongguan doit rubber products, guangdong, china). sampling was carried out at a specified periods using a syringe which was inserted into the center axis of the column. the column was packed with sandy soil as aquifer and activated carbon developed from date palm seeds wastes (reactive media) as barrier in the configuration and alignment illustrated in fig. 1. this column was then filled with distilled water that was fed slowly into the bottom of the column and forced upward through the medium in order to expel the air from the medium (soil and activated carbon). the contaminated solution with copper, which simulated the contaminated groundwater, was introduced into the column from storage tank controlled by gravity (constant head flow), flowmeter and two valves. two values of flow rate (7 and 17 ml/min) were selected for the column test experiments. the selection of these values was to satisfy the laminar flow, i.e., reynolds number (r) < 1 − 10 [9], which is the predominant situation for groundwater flow in the porous medium. monitoring of copper concentration along the length of the column in the effluent from sampling ports was conducted for a period of 7 days, then samples of water were taken regularly (after 1, 2, 4, and 7 days) from these ports and immediately introduced in glass vials and then analyzed by atomic adsorption spectrophotometer. the filling material in the column was assumed to be homogeneous and incompressible, and constant over time for water-filled porosity. the volumetric water discharge through the column cross section was constant over time and set as the experimental values. the copper inlet concentration was set constant. all tubing and fittings for the influent and effluent lines should be composed of an inert material. a solution of 1 g/l nacl in deionized water as a tracer was continuously fed into the column at four values of flow rate (5, 10, 15, and 20 ml/min) for a tracer experiment, adopting the same method of ujfaludi [10], to determine the longitudinal dispersion coefficient (dl) for the reactive medium (activated carbon) and sandy soil (aquifer). 4. results and discussion 4.1. fourier transform infrared analysis the fourier transfer infrared spectroscopy (ftir) analysis has been considered as a kind of direct mean for identifying the characteristic functional groups on the surface of the activated carbon, which are responsible for copper binding [11]. the ftir spectrums of activated carbon ziad t. abd ali al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 3444(2016) 37 samples after and before copper sorption were examined using a shimadzu ftir, 8000 series spectrophotometer. the displacement in the infrared frequencies support that carboxylic acid, alcohols, and sulfonates are the functional groups causing the sorption of copper onto activated carbon as shown in fig. 2, table 1,[12]. accordingly, the mechanisms that controlled the sorption of copper by using activated carbon may be the adsorption process supported by the presence of the functional groups described previously. fig. 1. schematic representation of column test. fig. 2. ftir spectrum of activated carbon (a) before and (b) after, loaded of cu (ii) table 1, functional groups responsible for copper sorption onto activated carbon. wave no. (cm -1 ) type of bond functional group displacement after sorption 3375.43 o-h carboxylic acid 19.29 1743.65 c=o carboxylic acid 3.86 1192.01 c-o carboxylic acid 65.58 1087.85 c-o-c alcohols 11.58 968.27 s-o sulfonates 7.72 (a) (b ) ziad t. abd ali al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 3444(2016) 38 4.2. influence of batch operating parameters 4.2.1. effect of contact time and initial ph of solution the effect of initial ph of the solution and the contact time on copper sorption is illustrated in fig. 3, where 0.5 g of activated carbon was added to a 50 ml of cu(ii) solution at 25 ºc. as the fig.3 shows, at the beginning, the increasing rate of adsorption was fast as the contact time increased till reaching the equilibrium time (60 min). this could be the result of the availability of many adsorbent sites for the cu(ii) adsorption. the adsorption rate was reduced because of the decreasing of the remaining vacant surfaces as result of formation of replusive forces between the cu(ii) on the solid surfaces and in the liquid phase [13]. as well as the reduction in the competition between cu(ii) and proton for the surface sites causes the increase in the removal of copper on increasing ph, this results in a reduce in columbic repulsion of the sorbing copper. however, the removal efficiency was decreased on increasing the ph value. fig.3 shows that at a ph of 6 the removal efficiency of cu(ii) was at its maximum value. fig. 3. removal efficiency of copper on activated carbon as a function of contact time and initial ph 4.2.2. effect of activated carbon dosage the effect of activated carbon dosage on the removal efficiency of the copper was examined at different dosages of activated carbon. these dosages were ranging from 0.2 to 1 g and added to 50 ml of copper solution as present in fig.4.this figure showed that the increasing of the activated carbon dosage from 0.2 to 0.6 g at fixed initial copper concentration will lead to improve the removal efficiency, this was because of a higher dosage of activated carbon in the solution leads to greater availability of sorption sites, it's also clear that after a dosage of activated carbon (0.6 g/50 ml), the maximum adsorption sets in; hence, even with further addition of activated carbon, the amount of copper bond to the activated carbon and its amount in solution remain constant. fig. 4. effect of activated carbon dosage onremoval efficiencies of cu(ii) 4.2.3. effect of initial copper concentration fig. 5 presents the effect of initial concentration of copper on its removal efficiency. its shows that when increasing the initial concentration of copper from 50 to 90 mg/l, the removal efficiency reduces from 96 to 74.4%, this represents the saturation of the active sites available on the activated carbon to interact with pollutant, so with increasing concentration the less favorable sites became involved in the process[14]. fig. 5. effect of initial copper concentration on removal efficiency of copper on activated carbon 0 20 40 60 80 100 0 10 20 30 40 50 60 70 80 90 r e m o v a l e ff ic ie n c y % time (min) co=50 mg/l, dose=0.5 g/50 ml, agitation speed=200 rpm ph=7 ph=6 ph=5 ph=4 ph=3 0 20 40 60 80 100 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 r e m o v a l e ff ic ie n c y % activated carbon (g/50ml) co=50 mg/l, ph=6, t=60 min, agitation speed=200 rpm 40 50 60 70 80 90 100 40 50 60 70 80 90 r e m o v a l e ff ic ie n c y % co (mg/l) dose=0.6 g/50 ml, ph=6, t=60 min, agitation speed=200 rpm ziad t. abd ali al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 3444(2016) 39 4.2.4. effect of agitation speed nearly 7% of the copper was removed before shaking (agitation speed = 0) and with the increase of the rate of shaking, the uptake increases, as illustrated in fig. 6 . on increasing agitation speed from 0 to 250 rpm, there is a gradual increase in copper uptake, at which about all of the copper (100%) is removed. this can be due to improving the diffusion of copper towards the surface of the reactive medium (activated carbon) and more contact between the binding sites and the copper in the solution. fig. 6. effect of agitation speed on removal efficiency of copper 4.3. sorption isotherms the parameters that give the higher removal efficiency of copper at its initial concentration of 50 mg/l on activated carbon were ph of 6, agitation speed of 250 rpm, an equilibrium time of 60 min, and activated carbon dosage of 0.6g/50ml. the results of the sorption experiment were fitted with the previously described linearized form of five isotherm models. the fitted parameters and coefficient of determination (r 2 ) for each model are illustrated in table 2. in comparison with the other models, the langmuir isotherm model provided the higher correlation for copper sorption on activated carbon, therfore the langmuir isotherm model was used to describe the copper sorption on these media in the partial differential equation (pde) governing the transport of a copper in one dimension continuous mode. considering the sandy soil (aquifer) as a nonreactive medium (inert) is one of the main aspects of the present study, so that just the adsorbate (copper) and adsorbent (activated carbon) are examined in batch experiments. table 2 parameters of isotherm models for sorption of copper onto activated carbon. isotherm models parameter langmuir b (l/mg) 4.874 qm (mg/g) 4.374 r2 0.9986 freundlich kf (mg/g)(l/mg)1/n 3.662 n 21.32 r2 0.9533 elovich qm (mg/g) 10.033 ke (l/mg) 0.3709 r 2 0.9497 temkin ∆q (kj/mole) 7.0729 ko (l/mg) 1.0007 r2 0.9221 kiselev k1 (l/mg) 0.5431 kn -0.8201 r2 0.9242 4.4. longitudinal dispersion coefficient table 3 presents the results of experimental work representing the measurement of longitudinal dispersion coefficient (dl) at different values of velocity (v) for soil and activated carbon had the following linear forms equations (7, and 8) [10]: dl = 6.490 v + 0.5325 (r 2 =0.9960)for soil …(7) dl=12.889 v + 0.0325 (r 2 =0.9953)for ac …(8) the longitudinal hydrodynamic dispersion of these equations has the general form of coefficient as in equation (9) [15]: 𝐷𝐿 = 𝛼𝐿𝑉 + 𝜏𝐷𝑜 …(9) where do = molecular diffusion coefficient, and τ = tortuosity. as cited by holzbecher, the τ value for theoretical work is equal to the porosity (n) [15]. in the present study the molecular diffusion coefficient of copper in the water (do) used was 9.7 × 10 −6 cm 2 /s [16]. therefore the longitudinal dispersivity (αl) is 6.49 and 12.889 cm for soil and activated carbon, respectively 0 20 40 60 80 100 0 50 100 150 200 250 r e m o v a l e ff ic ie n c y % agitation speed (rpm) co=50 mg/l, dose=0.6 g/50ml, ph=6, t=60 min ziad t. abd ali al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 3444(2016) 40 table 3, measured values of the longitudinal dispersion coefficient and dispersivity for used mediums as a function of mean pore velocity. flow rate (ml/min) 5 10 15 20 sandy soil (aquifer) v (cm/s) 0.01 0.02 0.03 0.04 re 0.0179 0.0359 0.0538 0.0718 dl (cm 2 /s) 0.593 0.670 0.725 0.791 αl (cm) 6.490 activated carbon (prb) v (cm/s) 0.009 0.018 0.027 0.036 re 0.0696 0.1392 0.2088 0.2784 dl (cm 2 /s) 0.158 0.250 0.381 0.501 αl (cm) 12.889 4.5. modeling application advection dispersion processes is the cause of copper transport in a porous medium, so that the one-dimensional system of copper transport in a porous media can be represented by the following equation (10) [17]: 𝐷𝑧 𝜕2𝐶𝐶𝑢 𝜕𝑧2 − 𝑉𝑧 𝜕𝐶𝐶𝑢 𝜕𝑧 = 𝜕𝐶𝐶𝑢 𝜕𝑡 + 𝜌𝑏 𝑛 𝜕𝑞 𝜕𝑡 …(10) where ccu = copper mass concentration in water, vz = velocity of flow, dz = longitudinal dispersion coefficient in the z direction, ccu = copper mass concentration in water, ρb = dry adsorbing material bulk density, and q = copper concentration on solid,. , the second term (q) on the right side of equation (10) can be changed by the langmuir model equation (1) under isothermal conditions. the initial copper concentrations are assumed to be zero throughout the entire flow domain and the boundary conditions used in comsol multiphysics 3.5a are reported in equation (11): lower boundary (at z = 0)∶ ccu = 50 mg/l upper boundary (at z=50 cm): advective flux as in equation (11): 𝜕𝐶𝐶𝑢 𝜕𝑧 = 0 …(11) interior boundaries in the barrier zone (i.e., at z=20 and 35 cm): continuity. with and without the presence of prb the concentration lines of copper in the aquifer were calculated by the comsol multiphysics 3.5a software at two different values of flow rates (7 and 14 ml/min) and at different time intervals as shown in fig.7. this figure shows that the propagation of the copper plume was restricted by the barrier and this propagation will be increased as increasing flow rate. the prb thickness effect varied from 0 to 25 cm as shown in fig. 8, where the copper treatment in the down gradient of the barrier (z = 35 cm) at a rate of flow of 20 ml/min. it is clear that the copper treatment will be better with the increment of the prb thickness. this is due to the greater retention time of the copper solution that leads to better sorption process. however, on increasing the travel time, the barrier starts to saturate; so that the retardation factor of the copper was decreased, this means that the percentage functionality of activated carbon for containing pollutant was reduced. ziad t. abd ali al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 3444(2016) 41 fig. 7. representation of copper concentration along the length of the column with and without presence of barrier at two values of flow rate using comsol software. fig. 8. concentration of copper versus time of various barrier thickness. in addition, to investigate the relation between prb thickness and its longevity, comsol multiphysics 3.5a was used as valid tool. the time required for maintaining the concentration of contaminant down gradient of the barrier to less than the quality limit prescribed for drinking water is the definition of the "longevity". under two different values of flow rate the longevity of the barrier increased in a linear trend with increasing the thickness of the barrier for copper as illustrated in fig. 9 . 0 0.01 0.02 0.03 0.04 0.05 0 5 10 15 20 25 c o n c e n tr a ti o n o f c o p p e r (k g /m 3 ) time (day) q=20 ml/min, z=35 cm barrier thickness=0 cm barrier thickness=5 cm barrier thickness=10cm ziad t. abd ali al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 3444(2016) 42 fig. 9. relationship between the thicknesses of the barrier and its longevity as predicted by comsol software. fig. 10 illustrate a comparison between the comsol solution (theoretical) experimental results for copper concentrations during the transport the copper plume at two different flow rates in a various periods of times along the tested column. it's obvious there is nearly an agreement between the theoretical and experimental results. in addition, to find the degree of agreement between these results a statistical tool was used (rmse) [18]. the root-mean squared error values don’t exceed 0.08, confirming a good agreement. fig. 10. comparison between experimental results and comsol solution for copper concentrations at two values of flow rate. 5. conclusions 1. the batch results indicated that there are several parameters such as contact time, initial ph of the solution; initial copper concentration, activated carbon dosage, and agitation speed affect the sorption process the sorption process between copper and activated carbon. the best values of these parameters that will achieve the maximum removal efficiency of copper (100%) were 60 min, 6, 50 mg/l, 0.6 g/50 ml, and 250 rpm, respectively. 2. copper sorption data on activated carbon was correlated reasonably well by the langmuir sorption model with coefficient of determination (r 2 ) of 0.9986. 3. the fourier transfer infrared spectroscopy (ftir) analysis proved that carboxylic acid, alcohols, and sulfonates are the functional groups responsible for the sorption of copper onto activated carbon 4. the numerical solutions that are solved by comsol multiphysics 3.5a to describe the one dimension equilibrium transport of copper along the length of aquifer and prb proved that the activated carbon barrier is an efficient technique to restrict the contaminant plume. these results showed that the greater thickness of prb results in a better treatment of copper and that the barrier starts to saturate with contaminant as a function of the travel time. however, a good agreement between the predicted (theoretical) and experimental results with rmse not exceeded the 0.08 0 100 200 300 400 500 600 700 800 0 1 2 3 4 5 6 l o n g e v it y ( d a y ) thickness of barrier (m) q=7 ml/min q=14 ml/min 0 0.01 0.02 0.03 0.04 0.05 0.06 0 10 20 30 40 50 c o n c e n tr a ti o n o f c o p p e r (k g /m 3 ) distance from the bottom of column (cm) q=7 ml/min 1 day (comsol) 2 day (comsol) 4 day (comsol) 7 day (comsol) 1 day (experiment) 2 day (experiment) 4 day (experiment) 7 day (experiment) ziad t. abd ali al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 3444(2016) 43 proved these methods are effective and efficient tools in description of pollutant transport phenomena adopted here 5. experimental results proved that the activated carbon developed from date palm seeds wastes was a good choice as an inexpensive and efficient reactive material for permeable reactive barrier to remove the copper from contaminated groundwater 6. references [1] chung, y. w., kim, j., and kong, s. h. (2011). “performance prediction of permeable reactive barriers by threedimensional groundwater flow simulation.” int. j. environ. sci. dev., 2(2), 138–141. [2] zhu b., fan t., zhang d., (2008) , "adsorption of copper ions from aqueous solution by citric acid modified soybean straw", journal of hazardous materials 153 300–308. [3] bear, j. (1979)."dynamics of fluids in porous media" , elsevier, new york, 763. [4] di natale f., di natale m., greco r., lancia a., laudante c., and musmarra d. (2008). “groundwater protection from cadmium contamination by permeable reactive barriers.” j. hazard. mater., 160(2–3), 428– 434. [5] babel s., kurniawan t.a., (2003), "low-cost adsorbents for heavy metals uptake from contaminated water: a review", j. hazard. mater. b97 219–243. [6] hamdaou o. i, naffrechoux e., (2007), "modeling of adsorption isotherms of phenol and chlorophenols onto granular activated carbon", j. hazard. mater. 147 381–394 [7] ahmed el nemr∗ , azza khaled, ola abdelwahab, amany el-sikaily, (2008), "treatment of wastewater containing toxic chromium using new activated carbon developed from date palm seed", journal of hazardous materials 152 ,263–275 [8] wang, s., nan, z., li, y., and zhao, z. (2009). “the chemical bonding of copper ions on kaolin from suzhou, china.” desalination, 249(3), 991–995. [9] [9] delleur, j. (1999). "the handbook of groundwater engineering", crc press, boca raton. [10] ujfaludi, l. (1986). “longitudinal dispersion tests in non-uniform porous media.” hydrol. sci. j., 31(4), 467–474. [11] chen, j. p., wang, l., and zou, s. w. (2008). “determination of lead bio-sorption properties by experimental and modeling simulation study.” chem. eng. j., 131(1–3), 209–215. [12] doke, k. m., yusufi, m., joseph, r. d., and khan, e. m. (2012). “bio-sorption of hexavalent chromium onto wood apple shell: equilibrium, kinetic and thermodynamic studies.” desalin. water treat. 50(1–3), 170–179. [13] el-sayed g.o., dessouki h.a., ibrahim s.s., (2010) , "bio-sorption of ni(ii) and cd(ii) ions from aqueous solutions onto rice straw", chem. sci. j. 9, 1–11. [14] qadeer, r., and rehan, a. h. (2002). “a study of the adsorption of phenol by activated carbon from aqueous solutions.” turk j. chem., 26, 357–361. [15] holzbecher, e. (2007)." environmental modeling using matlab", springer, berlin. [16] quickenden t. i., jiang x.,(1984)" the diffusion coefficient of copper sulphate in aqueous solution", electrochimica ,vol. 29, no. 6, pp.693-700. [17] reddi, l. n., and inyang, h. i. (2000). "geoenvironmental engineering principles and applications", marcel dekker, new york. [18] anderson, m. p., and woessner, w. w. (1992). "applied groundwater modeling: simulation of flow and advective transport, 2nd ed.", academic press, san diego. (2016) 3444، صفحت 2، العذد12دجلت الخىاسصمي الهىذسيت المجلمصياد طاسق عبذ علي 44 استخذام الكاسبىن المىشط المطىس مه بزوس تمش الىخيل العشاقى كجذاس تفاعلى وفار لمعالجت المياي الجىفيً الملىثً بالىحاس صياد طاسق عبذعلي بغذاد جبيعّ/ كهٛت انُٓذعت/ ة قغى انُٓذعّ انبئٙ z.teach2000@yahoo.com :انبشٚذ االنكخشَٔٙ ةالخالص حًش انُخٛم كجذاس حفبعهٙ َفبر الصانّ انُحبط يٍ انًٛبِ انجٕفّٛ بزٔسانخحقق يٍ ايكبَٛت اعخخذاو انكبسبٌٕ انًُشظ انًطٕس يٍ ٚخى فٙ ْزا انبحذ عًهٛبث انذفع . ببعخخذاو حبيض انكبشٚخٛك انًشكض( dehydration method) حًش انُخٛم عٍ طشٚق عًهٛت بزٔس انكبسبٌٕ انًُشظ صُع يٍ . انضحهّ (batch )انُخبئج .ِحى فشضٓب عهٗ آَب خبيم ةانشيهٙ ةحى اعخخذايٓب الٚجبد خٕاص انخٕاصٌ فٙ عًهٛت ايخضاص انُحبط عهٗ عطح انكبسبٌٕ انًُشظ بًُٛب انخشة حى اعخخذاو عًٕد ببحجبِ . ببنًقبسَّ ببنًٕدٚالث االخشٖ بُفظ ظشٔف انذساعّ الَكًٛشْٕاالفضم حطببقب نٕصف عًهٛت االيخضاص انًٕدٚمانعًهّٛ اشبسث ببٌ َخبئج ال. ٔانخٗ حى حهٓب ببعخخذاو بشَبيج انكٕيغٕل( adv. disp. equation)نًحبكبة جشٚبٌ انًٛبِ انجٕفّٛ ببحجبِ ٔاحذ يعخًذا عهٗ يعبدنّ ( 1d)ٔاحذ ظٓش حٕافق جٛذ قذحضداد بضٚبدة عًك انحبجض ٔ ةدٔسا يًٓب فٙ اعبقّ انًهٕد ٔكزنك اٌ عًهٛت االصال ٚؤد٘انعذدّٚ ٔانعًهّٛ اربخج اٌ انجذاس انخفبعهٗ انُفبر . يببٍٛ َخبئج انكٕيغٕل ٔانعًهٗ قاسم دوس وتحسين وعقيل al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 1 -14 (2013) an investigation study of thinning distribution in single point incremental forming using fem analysis qasim mohamed doss* tahseen fadhel abaas** aqeel sabree bedan*** *college of engineering / university of baghdad **,***department of production engineering and metallurgy / university of technology (received 14 april 2013; accepted 29 may 2013) abstract single point incremental forming (spif) is a forming technique of sheet material based on layered manufacturing principles. the sheet part is locally deformed through horizontal slices. the moving locus of forming tool (called as toolpath) in these slices constructed to the finished part was performed by the cnc technology. the toolpath was created directly from cad model of final product. the forming tool is a ball-end forming tool, which was moved along the toolpath while the edges of sheet material were clamped rigidly on fixture. this paper presented an investigation study of thinning distribution of a conical shapes carried out by incremental forming and the validation of finite element method to evaluate the limits of the process as regards to the geometry of the final product. three conical products have been carried out during this study with different forming angles and depth. the process was simulated using fem program (ansys 11.0) and the results showed that the deviations between simulated and real values did not exceed of 6%. keywords: single point incremental forming (spif), experiments, thinning, finite element method. 1. introduction single point incremental forming (spif) process is interesting both industrially and scientifically. in the first case, sheet metal components can be manufactured without specific tools using a cnc milling machine. this kind of process can be produced complex parts in small batch or for single part. in particular, spif used as a rapid manufacturing process to custom-made parts. however, this advantage is limited by the important thinning of the sheet, the occurrence of defects. [1] in the spif process, thickness of formed part is evaluated by formula (1) which is called sinlow formula. this is usually utilized for the shear forming process. ) 2 sin( ψ π −= of tt …(1) where, (tf ) is final thickness, (to) is initial thickness and (ψ) is wall angle. the formula calculation shows that the thickness of vertical wall is zero. therefore, the capacity of spif process only can deform the wall angle less than 90 degrees. the parts having various steep walls are very difficult to apply this process. because the thickness of deformed part is calculated uniformly by formula (1) and the thickness of black is constant. significant advantages of this process over conventional forming include greater formability, low forming forces and generic tooling configuration. one of the major research problems of considerable interest to the sheet metal forming community is the accurate prediction of fracture in spif. this is important because an underestimation of the fracture depth will result in a loss of the advantage of enhanced formability of qasim mohamed doss al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 114 (2013) 2 the process and an overestimation will cause component failure during the forming process itself. furthermore, a better physical understanding of the mechanisms of deformation and fracture in spif is of great importance since this can aid the choice of appropriate process parameters for the process and can lead to modifications of the process to further enhance the achievable formability. aspect different steps of this process are shown in figure (1). [2] numerical investigations using fem were also conducted to investigate the final thickness and mechanisms in spif. this process modeled the contact between the tool and the sheet using a moving ball end tool method. fig. 1. single point incremental sheet metal forming process.[2] 2. material and testing 2.1. material for this study, the selected material is an aluminum (al-1050) sheet with an initial thickness of (0.9mm) and an initial hardness of (24 hv). its composition studied in state company for inspection and engineering rehabilitation activities (s.i.e.r)), and is given in table (1). table 1, chemical composition of aluminum 1050 sheet. material si% fe% cu% mn% mg% cr% ni% zn% al% al-1050 exp. 0.142 0.315 0.013 0.013 0.001 0.001 0.003 0.006 99.5 iso 0-0.25 0-0.4 0-0.05 0-0.05 0-0.05 0-0.03 0-0.03 0-0.07 99.5 2.2. tensile test in order to simulate the spif process by means finite element program, the value of some parameters was measured in tensile test. in practical, the mechanical characterization was performed with tensile testing machine, such as tensile strength of (90mpa) and young modules of (72 gpa) have peen obtained. [3] tensile test has been down in the university of technologyproduction engineering and metallurgy, strength of material lab; figure (2) presents tensile test setup. these tests result in (90o to rolling direction) because the strength in qasim mohamed doss al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 114 (2013) 3 this way is minimum according to literatures. [4] while, most of experimental work was done in isotropic condition due to axisymmetric product. table (2) defines the result of tensile test for aluminum sheet. fig. 2. tensile test of al-1050. table 2, mechanical properties for al-1050 sheet. material tensile strength mpa modulus of elasticity gpa poissons ratio elongation % on 50 mm g.l. vickers hardness vpn iso al-1050 exp. 90 72 0.33 37 24 al-1050-‘o’ iso 80-100 70-75 0.33 35-42 20-30 2.3. experimental device and forming strategies 2.3.1. experimental device to validate the numerical simulations, experiments were conducted. for this purpose, a dedicated apparatus was designed and realized. the representation of this tooling is done in figure (3). it is composed of a fixed die support, a modular die, a fixed blank holder clamped with the die by screws and the forming tool (ball end tool). the modular defined different shapes depending on the geometry of the part to be produced. in particular, it limited the non-desired bending obtained on the base of the part by specifying the nearest contour of the final part. qasim mohamed doss al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 114 (2013) 4 fig. 3. illustrated the proposed clamping device. 2.3.2. the shape of the part the carried out with a cone with different depth and slope angles, beginning from a square sheet with a side of 225 mm, the tool paths, whose example are illustrated in figure (4) are characterized for forming of cone is a sequence of circular coils generates the tool path. the first of which presents (d=160mm) and feed a long depth has a step (0.3mm) and final circle is (10mm). fig. 4. isoplaner tool path. [5] a conical shape is proposed to investigate the single point incremental sheet forming of thin sheet. the geometry definition is illustrated in figure (5 &6). this shape has been chosen because there is alternation between the (x, y) and the z directions during the forming process. therefore it will be possible to determine the influence of the tool position on the forming thinning. qasim mohamed doss al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 114 (2013) 5 fig. 5. proposed conical cup profile used in this research (depth =47, 80 &110mm). fig. 6. proposed 3dcad model used in this research (depth=47mm). 2.3.3. forming strategies the forming was carried out on vertical cnc machine using steel tool (tool steel material(x210)) with ball end diameter (12mm), different strategies are possible to produce the part. for the conical shape, one approach was considered: isoplaner toolpath. figure (7) shows a photograph of an experimental test, for every test the tool has been put in rotational speed of (100r.p.m) and a feed rate of (750mm/min) was set out. qasim mohamed doss al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 114 (2013) 6 depth (47mm) depth (80mm) depth (110mm) isoplaner toolpath actual forming time=55.5 min actual forming time=95.4 min actual forming time=134.9min maximum forming angle 41.9o 63o 78o fig. 7. geometrical parameters. 3. numerical methods an overview of the analysis method used in the research is given in the chart in figure (8). the chart presents in detail the phase of preprocessing the data corresponding to the physical model of the forming process. complex differential equations describing the applicable physics can be approximated with algebraic expressions within each element. in the case of structural finite element analysis (fea), these simplified expressions relate forces to displacements within each element; the expressions are then assembled into matrix form, dkf *][= …(2) where (f) is the force vector applied to a structure, (d) is the resultant displacement vector, and [k] is the stiffness matrix of the system. at the beginning, there are defined the formable and stiff bodies based on the blank's and the tool geometry. the geometry is the one specific for the moment of process initiation. based on the geometry of the formable body, this is meshed into finite elements. [6] to the set of elements thus defined, the following are also associated: • material data, specifically the tensile test. • geometrical data, namely the date of profile. • define boundary condition and type of element; based on recommendations from the specialty literature. qasim mohamed doss al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 114 (2013) 7 o ut pu t pr oc es si ng in pu t maximum thinning (25-30%) physical model of the processing system define tool geometry and model geometry define the boundary condition of the process and element type finite element analysis (fea) define material properties pre-processing ansys 11.0 desired shape modify tool or part geometry, material properties, friction strain analysis shape analysis solving the problem fig. 8. simulation flowchart that illustrated input, analysis, and output condition in formability analysis. qasim mohamed doss al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 114 (2013) 8 3.1. defined blank element type the element used to simulate the blank is (visco106), visco 106 is used for 2-d modeling of solid structures, and it is defined by four nodes having up to three degrees of freedom at each node (x, y and z). 3.2. material properties a pure aluminum (aa1050) was used in this work, the specific mechanical properties result from stress-strain curve from tensile test illustrated in table (3). table 3, show the material properties of the blank used in fe model. 3.3. boundary conditions 3.3.1. displacement and loading 1. the die was held fixed by nodal constraints in the x and y-direction n1, n2 and n3. 2. the fixture was constrained so as to allow movement in the x,y-direction. 3. the blank was hold by fixture at n4 and n5, and hold in center line and allow to movement in y-axis only at n6. 4. the punch motion was specified in curve profile with constant speed. figure (9) illustrated the fe model and boundary condition. fig. 9. show finite element boundary conditions. density ρ 2700 kg/m3 young’s modulus e 75 gpa poisson’s ratio ν 0.33 yield stress σy 78 mpa tangent modules eτ 0.2 gpa qasim mohamed doss al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 114 (2013) 9 3.3.2. coulomb friction model in this work, the value of friction coefficient (0.04) was used for simulation model. 3.3.3. contact three contact interfaced were defined between the tool, die and blank. 1. contact between tool and upper blank surface. 2. contact between tool and upper blank surface lower blank surface die interface. 3. contact between blank holder and upper blank surface –lower blank surface die interface. the contact between the tool, blank holder, and die illustrated in figure (10). the tool and work piece like rigid to flexible contact, and from ansys the nod-to-surface contact model and element target 69 and contact 71 are used to represent the contact between these reigns. figure (11) present the fe-output while figure (12) is a plot of a typical stress legend used to describe the motion of the tool to a depth of 110 mm. and the applied blank holder force using screw. fig.10. illustrated three type of contact used in incremental forming. fig. 11. simulate forming part output from ansys package. qasim mohamed doss al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 114 (2013) 10 1 2 3 4 5 6 7 8 fig. 12. sequences of incremental forming model using ansys 11.0. qasim mohamed doss al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 114 (2013) 11 fig.13. illustrated thickness distribution for forming depth (47). fig. 14. illustrated thickness distribution for forming depth (80) fig. 15. illustrated thickness distribution for forming depth (110). qasim mohamed doss al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 114 (2013) 12 fig. 16. illustrated thickness distribution for maximum forming angle (41.9o). fig. 17. illustrated thickness distribution for maximum forming angle (63o). fig. 18. illustrated thickness distribution for maximum forming angle (78o). qasim mohamed doss al-khwarizmi engineering journal, vol. 9, no. 3, p.p. 114 (2013) 13 4. results conclusions 1. fem was fully applied to the simulation of a cone whose results were compared to the theoretical (sin law) and to experimental measurements in terms of thickness. 2. from the results shown in figures (13,14 and 15) it clearly seen that the predicted behavior of thinning distribution with depth are coincided well with both theoretical (sin law) and practical behaviors and the overall deviation did not exceed 6%. 3. two types of analyses through the finite element method: analyses for determining the influence of depth parameter on thinning distribution, and analyses for determining the influence of wall angle on thinning distribution. that present when forming angle increase with respect to forming depth the thinning increase as shown in figures (16,17 and 18). 4. the deviation between the actual thickness and simulate are increases with respect to depth of forming increase due to increasing of spring back and bending stress on internal wall of part. 5. using fem, the wall angle affected on thinning behavior, and the maximum thinning is locate in the maximum forming angle. 6. using fem, it was found that both throughthe-thickness shear and local bending of the sheet around the tool plaied a role in fracture in the spif process, which happened at forming depth (120mm) when the product was failure. 5. references [1] s. thibaud, r. ben hmid, f. richard and p. malécot’ “a fully parametric toolbox for the simulation of single point incremental sheet forming process: numerical feasibility and experimental validation”, ”, elsevier ltd, simulation modelling practice and theory, vol. 29, 2012. [2] d. xu, rajiv malhotra, n. venkata reddy, jun chen and jian cao, “analytical prediction of stepped feature generation in multi-pass single point incremental forming”, elsevier ltd, journal of manufacturing processes, vol. 14, 2012. [3] q. mohamed doss, tahseen fadhel abaas and aqeel sabree bedan, “the effect of tool path strategy on twist behavior in single point incremental sheet metal forming”, journal of engineering, baghdad university, vol. 4, 2013. [4] r. malhotra, liang xue, ted belytschko and jian cao, “mechanics of fracture in single point incremental forming”, elsevier ltd, journal of materials processing technology, vol. 212, 2012. [5] c. felipe guzm, jun gu , joost duflou , hans vanhove , paulo flores and anne marie habraken, ”study of the geometrical inaccuracy on a spif two-slope pyramid by finite element simulations”, elsevier ltd, international journal of solids and structures, vol. 49, 2012. [6] s. dejardin, s. thibaud, j.c. gelin and g. michel, “experimental investigations and numerical analysis for improving knowledge of incremental sheet forming process for sheet metal parts”, elsevier ltd, journal of materials processing technology, vol. 210 363–36, 2010. )2013( 1-14 ، صفحة3، العدد9مجلة الخوارزمي الھندسیة المجلد قاسم محمد دوس 14 دراسة توزیع التخصر في عملیات التشكیل النقطي المتزاید باستخدام طریقة تحلیل العناصر المحددة ***عقیل صبري بدن** تحسین فاضل عباس* قاسم محمد دوس جامعة بغداد/ كلیة الھندسة * الجامعة التكنولوجیة/ قسم ھندسة االنتاج والمعادن ***،** الخالصة عدة التشكیل تعتمد طریقة التشكیل النقطي التزایدي على مبدا التشكیل للطبقات االفقیة المتوازیة وصوال للتشكیل النھائي للمنتج وذلك من خالل حركة طرق التصمیم المعان بالحاسوب وتستخدم ھذه على مسار یعرف مسبقا باحدى " التي غالبا ماتكون عدة صلدة ذات نھایة كرویة مصنعة من الفوالذ المقاوم" ).المبرمجة(الطریقة لتشكیل الصفائح المعدنیة باستخدام مكائن التحكم الرقمي نامج التحلیل في ھذا البحث تم دراسة توزیع السمك لشكل مخروطي تم انتاجھ باستخدام عملیة التشكیل النقطي المتزاید وتم محاكاة العملیة باستخدام بر اكاتھا باستخدام برنامج تم انتاج ثالث اشكال مخروطیة بزوایا تشكیل واعماق مختلفة عملیا ومح.للعناصر المحددة لتنبوء بالتوزیع الحاصل للمنتج النھائي عن % ٦وتم التنبو بالشكل الناتج وتوزیع السمك نسبة لعمق التشكیل وزاویة المیالن واالنفعال وبانحراف للقیم الیتجاوز , )االنسز(تحلیل العناصر المحددة .القییم العملیة والنظریة المحسوبة 141153 al-khwarizmi engineering journal,vol. 12, no. 4, p.p. conversion of lignocellulosic material i asem hassan mohammed *department of chemical industries / institute of technology / middle technical university / baghdad **,*** faculty three/ university of technology/ ***email (received 3 march 2016; accepted 17 may 2016 http://dx.doi.org/10.22153/kej.2016.05.006 abstract enzymatic hydrolysis process of lignocellulosic biomass materials is difficult because of of biomass, which represents barriers that prevent complete hydrolysis to render biomass highly digestible in enzymatic hydrolysis process. in this research, pretreatment of willow wood was used. hydroxide (0.4 g ca(oh)2/g raw bioma for various periods of time including 1, 2, 3.5, 5 and 6 h, oxygen pressures as oxidativeagent (6, 9, 13.5, 17.8, 21 bar ab enzymatic hydrolysis were depended on the maximum overall yields of glucan pretreatment and enzymatic hydrolysis. the optimal conditions of pretreatment were as follow bar absolute, 0.26 g ca(oh)2/g raw biomass furthermore, the optimal values for low impact factors such as water loading was 15 g/g raw biomass and was less than 3 mm. the optimal conditions of enzymatic hydrolysis were as follow: g /g glucan in raw biomass, at substrate concentration enzymatic hydrolysis under these conditions were as follow: 96.00 g glucan/100 g of glucan in raw biomass, and 65.00 g xylan/100 g xylan in raw biomass. keywords: lime pretreatment, enzymatic hydrolysis, lignocellulosic biomass, willow wood 1. introduction lignocellulosic biomass is the most widely available source of carbohydrates, which can converted in to biofuel; however, this feedstock is not readily digestible, to overcome this diffi lignocellulose structure must be modifi pretreatment [1]. there are three major components inlignocellulosic biomass which one, hemicellulose and lignin. cellulose and hemicellulose are not directly availa bioconversion due to their intimate association with lignin [2]. enzymatic hydrolysis of lignocellulosic biomass has been shown to be limiting factor in khwarizmi engineering journal,vol. 12, no. 4, p.p. 141153 conversion of lignocellulosic material into fermentable s hassan mohammed* frank behrendt frankjürgen methner*** *department of chemical industries / institute of technology / middle technical university / baghdad faculty three/ university of technology/ berlin/ germany *email: asemh2005@yahoo.com ***email : frank_jürgen.methner@tu.berlin.de (received 3 march 2016; accepted 17 may 2016 http://dx.doi.org/10.22153/kej.2016.05.006 enzymatic hydrolysis process of lignocellulosic biomass materials is difficult because of of biomass, which represents barriers that prevent complete hydrolysis; therefore, pretreatment techniques are biomass highly digestible in enzymatic hydrolysis process. in this research, (non?) pretreatment of willow wood was used. a weight of 11.40 g of willow wood was mixed with an excess of /g raw biomass) and water loading (15 g/g raw biomass). lime pretreatment was carried out for various periods of time including 1, 2, 3.5, 5 and 6 h, with temperatures at 100, 113, 130, 147 and 160 oxygen pressures as oxidativeagent (6, 9, 13.5, 17.8, 21 bar absolute). the optimization of both pretreatment and depended on the maximum overall yields of glucan and xylan after two processes of lime pretreatment and enzymatic hydrolysis. the optimal conditions of pretreatment were as follow /g raw biomass. 2) 1.25 h, 155 0c, 21 bar absolute, 0.26 ca(oh) low impact factors such as water loading was 15 g/g raw biomass and was less than 3 mm. the optimal conditions of enzymatic hydrolysis were as follow: cellulase enzymeloading g /g glucan in raw biomass, at substrate concentration of 50 g/l during 72 h of enzymatic hydrolysis drolysis under these conditions were as follow: 96.00 g glucan/100 g of glucan in raw biomass, and 65.00 lime pretreatment, enzymatic hydrolysis, lignocellulosic biomass, willow wood. lignocellulosic biomass is the most widely ilable source of carbohydrates, which can be , this feedstock is o overcome this difficulty, must be modified through there are three major components biomass which one, cellulose, ellulose and hemicellulose are not directly available for their intimate association enzymatic hydrolysis of lignocellulosic own to be limiting factor in the conversion of biomass to chemicals and fuels, this limitation is due to inherent structural features (i.e., acetyl content, lignin content, crystallinity, surface area, particle size and pore volume) of biomass, which represents the barriers that prevent complete hydrolysis, therefore t the enzymatic digestibility of biomass, biomass must subject (reducing size ≤ 4 mm) and chemically ( alkali treatment) pretreatments biomass will become more readily available to enzymatically hydrolysis of their sugars by cellulase and hemicellulase enzymes and the resulting sugars which can be ethanol or other biofuel by microorganisms via fermentation process [3]. al-khwarizmi engineering journal 153 (2016) fermentable sugars frank behrendt** *department of chemical industries / institute of technology / middle technical university / baghdad enzymatic hydrolysis process of lignocellulosic biomass materials is difficult because of inherent structural features ; therefore, pretreatment techniques are necessary (non?) oxidative short-term lime 11.40 g of willow wood was mixed with an excess of calcium ss) and water loading (15 g/g raw biomass). lime pretreatment was carried out temperatures at 100, 113, 130, 147 and 1600c, and solute). the optimization of both pretreatment and after two processes of lime pretreatment and enzymatic hydrolysis. the optimal conditions of pretreatment were as follow: 1) 1.33 h, 1470c, 17.8 c, 21 bar absolute, 0.26 ca(oh)2/g raw biomass. low impact factors such as water loading was 15 g/g raw biomass and particle size cellulase enzymeloading was 0.1 50 g/l during 72 h of enzymatic hydrolysis the yield of drolysis under these conditions were as follow: 96.00 g glucan/100 g of glucan in raw biomass, and 65.00 the conversion of biomass to chemicals and fuels, this limitation is due to inherent structural features (i.e., acetyl content, lignin content, crystallinity, surface area, particle size and pore volume) of sents the barriers that prevent complete hydrolysis, therefore to increase the enzymatic digestibility of lignocellulosic must subject mechanically 4 mm) and chemically (e.g., acid/ alkali treatment) pretreatments. the treated biomass will become more readily available to enzymatically hydrolysis of their sugars by cellulase and hemicellulase enzymes and the sugars which can be fermented to ethanol or other biofuel by microorganisms via asem hassan mohammed al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 141153(2016) 142 alkali pretreatment processes utilize lower temperatures and pressures compared to other pretreatment technologies. alkali pretreatment may be carried out at ambient conditions, but pretreatment duration is measured in terms of hours or days rather than minutes or seconds [4].compared with acid processes, alkaline processes have less sugar degradation and many of the caustic salts can be recovered and/or regenerated. sodium, potassium, calcium, and ammonium hydroxide are suitable alkaline pretreatment agents. in lime pretreatment, calcium hydroxide ca(oh)2, water and an oxidizing agent (air or o2) are mixed with the biomass at temperatures ranging from 40 to 1600c for a period ranging from hours to weeks, two types of lime pretreatment which show high total sugar yields and they are currently used: short term and long term. short-term lime pretreatment involves boiling the biomass with a different limeloading, temperatures and with or without oxygen at different pressure [5, 9].long-term pretreatment involves using lower lime loading and temperatures (40-550c) for 4-6 weeks in the presence of air [6]. hydrolysis of carbohydrates includes breaking the polymer of cellulose and himecelluloseto their monomers. hydrolysis of cellulose gives glucose, whereas hydrolysis of hemicellulose results pentoses and hexoses. there are two basic methods to degrade the biomass to sugars: enzymatic hydrolysisand dilute acid hydrolysis, compared to dilute acid hydrolysis, enzymatic approachis promising because it can achieve high sugar yields and eliminate the need for largequantities of chemicals and the formation of inhibitory by-products during dilute acidhydrolysis. during the enzymatic hydrolysis we need the cellulose enzyme which is responsibleto catalyze cellulose degradation to glucose and the hemicellulose enzyme as additiveto improve the hydrolysis process, cellulaseenzyme is actually a complex mixture of severalenzymes including endoglucanase, exoglucanase and β-glucosidase [7] the main purposes of this study can be summarized as follows: (1) compositional analysis of willow wood by analyzing the biomass.(2) study the effect the different conditions of short-term lime pretreatment on raw willow wood and also on the enzymatic hydrolysis process.(3) optimize the pretreatment conditions ( pretreatment time, oxygen pressure, temperature, lime loading, water loading, and particle size) to give the best yield of glucanand xylanfor both pretreatment and enzymatic hydrolysis, derivative empirical model for kinetic degradation of lignin and carbohydrate and optimize of enzyme loading and substrate concentration of enzymatic hydrolysis process. 2. materials and methods feedstock for this study was willow wood type tordis ((salix viminalis x salix schwerinii) x salix viminalis). from a private plantation. approximately 5 bundles of tree stems of 2-3 inch diameter were harvested in january 2010 from private land in saxony-anhalt, germany. a part of them was taken for debarking, drying and chipping and then chips were milled by wood mill to pass a 8.0 mm round screen. then the milled feedstock was taken to reduce particle size pass a 2 mm round screen by using laboratory mill, the biomass was collected after comminution process, sieved to pass 20 mesh (0.850 mm) and 80 mesh (0.180 mm). stack the sieves in the following order, starting at the bottom: the bottom pan, 80, 20-mesh sieve and lid of stack. the purpose is converting a variety of biomass samples into a uniform material suitable for compositional analysis in a reproducible way.finally the samples are air-dried to a moisture content less than or equal to 10%.neither the particles retained on the 20 mesh nor the ones passing the 80 mesh were used, only those less than 20 mesh more than 80 mesh ware used [8]. because out this rang of particle size, there is a big deviation in carbohydrate and lignin contents. once the samples were prepared, the particles of biomass was re-packaged into polyethylene bags (either completely filled or tightly wrapped to reduce evaporation into the headspace), and stored frozen at -20 0c. when needed, the biomass was directly used. these procedures are based on the nrel (national renewable energy laboratory) standard procedure (preparation of samples for compositional analysis). 3. experimental setup and operation short-term lime pretreatment process was performed in a system of a reactor constructed from 30-cm long, 38-mm inside diameter, 304 stainless steel pipe with a 285-ml volume. the reactor was supplied at both of ends by fittings made of stainless steel, see figure -1-.to get the temperature profile of reaction progress inside asem hassan mohammed al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 141153(2016) 143 reactor, we used a bimetal stem thermometer (type k) was used and inserted inside the reactor through the pipe at the end of the reactor, thus the temperature can be recorded by usb thermocouple data logger every 5 sec. fig. 1. photograph of lime pretreatment reactor. oxygen used in the experiments was as compressed to the reactor at constant pressure (cp) in which oxygen was continuously provided during pretreatment at the desired pressure. cp was attained by using flexible tubing (1/8-inch stainless steel) connected to an oxygen tank. raw biomass (11.4 g dry weight) and excess of calcium hydroxide (0.4 g/g dry biomass) were placed in a beaker size 250 ml. the mixture was thoroughly mixed with deionized water (15 g/g dry biomass),then the mixture was placed in the reactor. the mixing process during the reaction progress was carried out by using a system of motion which consisted of electrical motor and set of levers which can move the reactor toward left and right around 50 rpm. after tightly capping, the reactor was preheated to 750c by water bath, and then placed in the preheated oven. the pretreatment temperature was maintained by inserting the reactor in a temperature-controlled tube-oven at desired temperature, time ofexperiments begin when the temperature of the reactor reaches the desired temperature. therefore we need some time between 30 to 40 minutes to achieve to desired temperature in most of the experiments. at the end of the pretreatment process, the reactor was cooled by pressurized air, depressurized slowly by the valve that is connected to the reactor, remove the reactor from the oven, cool it down in cold water and open it. the pretreated biomass was transferred to a convenient container using about 250 ml of deionized water. the slurry was then neutralized by titrating with 5.0-n hcl to measure unreacted lime. after that the solids were extensively washed with clear deionized water and filtered using a vacuum, filtration apparatus with what manglass fiber filter paper (particle retention = 2µm). once filtered, the biomass to be analyzed for composition was air-dried at room temperature. the weight of the dry biomass and its moisture content were recorded to account for the pretreatment yield of solids. the biomass was stored at -200c until used for analysis or enzyme hydrolysis. 4. compositional analysis samples of raw and treated willow wood were prepared for compositional analysis. then the biomass was extractedwith 95% ethanol for 24 h in a soxhlet apparatus. the extracted samples were acid hydrolyzed in two stages to determine the carbohydrate and lignincontents, the lignin fractionates into acid-soluble material and acidinsoluble material, the acid soluble lignin is quantified by uv-visible spectroscopy and the insoluble lignin is determined by gravimetric analysis. the analysis ofcarbohydrates was performed by hplc device by using rezex rpmmonosaccharide (rpm pb+2) column of hplc device, with refractive index detection (lab index 2000l refractive index detector). ashcontent was determined by weighing the sample before andafter ashingat 575 0c± 250c (fisher scientific, programmablemuffle furnace).table (1)shows the composition of the raw willow wood that is used in this study. asem hassan mohammed al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 141153(2016) 144 table1, composition of raw willow wood feedstock. std. dev average washed willow wood components ( g/ 100 g biomass) 0.14 41.00 40.09 41.10 40.90 40.70 glucane 0.13 16.65 16.70 15.60 16.60 17.70 xylane 1.25 4.45 5.83 5.00 3.00 4..00 mannan 0.05 2.00 2.00 2.00 1.90 2.00 galactan 0.11 25.85 25.90 25.80 26.00 25.70 lignin 0.15 6.00 6.00 5.90 6.20 5.80 extarctive 0.03 0.82 0.82 0.86 0.80 0.8 ash 0.06 2.72 2.75 2.60 2.80 2.8 acetyl 99.50 99.00 99.66 98.50 98.6 total 5. results and discussion 5.1.lime pretreatment oxidative short-term lime pretreatment is an effective method for improving lignocellulose digestibility, partial removal of lignin allowed some of biomass of swelling, increased internal surface area, removes acetyl and the various uranic acid substitutions on hemicellulose and larger median pore volume, all of which enhanceenzyme accessibility to carbohydrate polymers. the experimental conditions for this study were selected as shown in table (2). table 2, pretreatment conditions. variables conditions oxygen pressure 6-21 bar( absolute) temperature 100160 c0 time 1-6 h lime loading 0.4 ca(oh)2 / g dry biomass water loading 15 g h2o / g dry biomass previous studies [9] showed that pretreatment time, temperature and oxygen pressure have greaterimpact than water loaded and lime loading on delignification; therefore , the pretreatment condition were conducted to hold the low impact variables constant while systematically change the high impact variables. after determined the high impact, the low impact then investigated, and the experiments started with excess lime loading of 0.4 g (ca(oh)2/g dry biomass) because normally the lime consumption is between 0.1-0.3g (ca(oh)2/g dry biomass) [1]. after completing of the pretreatment, back filtration with hcl to determine the excess lime and to calculate theoretical lime consumption. to determine the desired loading of water, water loading must be provided in a sufficient quantity to make this mixture (water, wood particle and lime) slurry, we found the minimum water loading which make the mixture homogeneous was (15 g h2o/g dry biomass) . therefore, we supposed it as optimum loading. to determine the high impact variables (temperature, time, oxygen pressure)a statistical design was used, and then the corresponding data was be collected and analyzed by appropriate statistical methods to achieve valid and objective conclusions. in the present work, the response surface methodology type (central composite design) has been used to plan the experiments and subsequent analysis of the collected data. if the response is well-modeled by a linear function of the independent variables, then the approximating function is the first order model, but if there is a curvature in the system, then the polynomial is of higher degree such as the second-order expression. as mentioned, the aims of this work involve the study of effect of temperature, oxygen pressure and pretreatment time on the (pretreatment yield and their content on the treated biomass). on the other hand, the study also aims to determine which lime pretreatment conditions cause the greatest increase in pretreated willow wood digestibility which gives highest pretreatment yield (total sold mass recovery). pretreatment yields specify the quantity of the component (i.e., lignin, glucan or xylan) in the raw biomass was found in the pretreated biomass. thus they assess pretreatment. pretreatment yield (yp) which also known recovery yield of total mass or yield of total solid. table (3) shows the results of recovery yield of total mass (yp) and total mass remaining. generally, the tendency of more solubility is for high temperatures, long pretreatment times and high pressure. also the rate of solubility increases along time at all temperatures and especially when increasing the oxygen pressure. asem hassan mohammed al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 141153(2016) 145 table 3, pretreatment yield of total mass with pretreatment conditions. pretreatment conditions pretreatment yield ex.no temperature, c0 pressure, bar time, h recovery total mass. g yp 1 147 17.8 5.0 6.090 0.535 2 113 17.8 5.0 7.700 0.675 3 147 9.2 5.0 6.450 0.565 4 147 17.8 2.0 6.810 0.597 5 113 9.2 5.0 8.160 0.715 6 113 17.8 2.0 8.550 0.750 7 147 9.2 2.0 7.420 0.650 8 113 9.2 2.0 8.900 0.780 9 160 13.5 3.5 5.740 0.504 10 130 21.0 3.5 7.110 0.623 11 130 13.5 6.0 6.750 0.592 12 100 13.5 3.5 9.210 0.807 13 130 6.0 3.5 7.750 0.679 14 130 13.5 1.0 8.350 0.732 15 130 13.5 3.5 7.540 0.661 16 130 13.5 3.5 7.560 0.663 17 130 13.5 3.5 7.530 0.660 18 130 13.5 3.5 7.550 0.662 the pretreatment yields of interest include: glucan pretreatment yields, yg (i.e., glucan remaining in the solids after pretreatment), xylan pretreatment yields, yx (i.e., xylan remaining in the solids after pretreatment), and lignin pretreatment yields, yl (i.e., lignin remaining in the solids after pretreatment).table(4) shows pretreatment yield of glucan and xylan. for all conditions, glucan yields were above 90 g glucan recovered/100 g glucan in raw biomass. in case of xylan, the degradation was much faster than glucan. in general, less carbohydrate was recovered when the solids underwent aggressive pretreatments (higher temperature, higher oxygen pressure and longer time). table 4, pretreatment yield of glucan and xylan with pretreatment conditions. pretreatment conditions pretreatment yield ex. no temperature, c0 pressure, bar time, h glucane recovered. g glucane yield xylan recovered. g xylan yield 1 147 17.8 5.0 4.324 0.927 0.800 0.422 2 113 17.8 5.0 4.395 0.942 1.051 0.555 3 147 9.2 5.0 4.386 0.941 0.825 0.436 4 147 17.8 2.0 4.392 0.942 0.951 0.502 5 113 9.2 5.0 4.433 0.950 1.057 0.558 6 113 17.8 2.0 4.543 0.974 1.154 0.610 7 147 9.2 2.0 4.526 0.970 1.007 0.532 8 113 9.2 2.0 4.628 0.992 1.291 0.682 9 160 13.5 3.5 4.218 0.904 0.796 0.420 10 130 21.0 3.5 4.331 0.929 0.959 0.314 11 130 13.5 6.0 4.325 0.927 0.923 0.487 12 100 13.5 3.5 4.605 0.987 1.473 0.778 13 130 6.0 3.5 4.382 0.987 1.123 0.593 14 130 13.5 1.0 4.580 0.982 1.169 0.617 15 130 13.5 3.5 4.411 0.946 1.025 0.541 16 130 13.5 3.5 4.417 0.947 1.008 0.532 17 130 13.5 3.5 4.405 0.945 1.024 0.541 18 130 13.5 3.5 4.416 0.947 1.025 0.541 asem hassan mohammed al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 141153(2016) 146 by using statistical program (statisticaprogram software),relationships were obtained between the expected values of pretreatment yields of different components with pretreatment conditions as follows: �� = +1.72070 − 6.884� − 3 × �� − 0.011937 × �� + 8.54� − 4 × �� − 4.433� − 5 × ���� − 1.224� − 5 × ���� − 5.212� − 6 × ���� + 3.862� − 7 × �� � + 3.795� − 4 × �� � + 2.387� − 7 × �� �(r=98) …( 1) �� = +1.23308 − 2.326� − 3 × �� + 5.563� − 3 × �� + 8.232� − 4 × �� − 3.266� − 5 × ���� + 2.2639� − 6 × ���� + 1.269� − 6 × ���� + 5.192� − 6 × �� � − 1.213� − 4 × �� � + 6.708� − 7 × �� �(r=87) … (2) �� = +2.461 − 0.023 × �� + 0.0177�� − 1.047� − 3 × �� + 5.617� − 5 × ���� + 5.847� − 8 × ���� + 2.723� − 5 × ���� + 6.841� − 5 × �� � − 1.508� − 3 × �� � + 4.809� − 7 × �� �(r=89) …(3) where: x1:temperature , x2:pressure, x3:time . these equations include all the terms regardless of their significance which was more 0.95. it can be seen that the model is in a good fit with high value of regression coefficient (r) ,and all of the statistical models of different components are statistically significant because they have p-values lower than 0.05. these equations are valid for temperatures between 112 and148c0, pressure values ranging from 9 to 18 bar (absolute) and the pretreatment time between 2 and 5 hours (according with this type of central composite design). 5.2. lignin degradation delignification depends highly on temperature and the presence of oxygen. thus higher temperature, oxygen pressure and longer pretreatment time result in much higher lignin degradation. figures (2a, 2-b, 2-c) represent the curves of lignin yields that were derived from statistical program, which based on the above equation, corresponding to varying pressure of oxygen and pretreatment while temperature was held at 113, 130 and 1470c. the color gradient of these figures, which begins with the orange color and ends with dark blue, orange color indicate the highest undesirable lignin yield while dark blue represents the lowest desirable lignin yield. in these figures we observe the effect of the oxygen pressure and pretreatment time on the lignin yield at constant temperature. it can also be observed that increasing temperature leads to shifts of lignin yield toward more removal. the highest recorded delignification was obtained for the pretreatment at 147 0c, 17.8 bars and 5 h. the yield was 19.3 g of lignin remaining/100 g lignin in the raw biomass. whereas a very poor delignification response was achieved for the pretreatment at 100.0 0c, 13.5 bar and 3.5 h, the lignin yield was 78 g of lignin remaining/100 g lignin in the raw biomass. fig. 2-a. x: time (min), y: pressure (bar), temperature 113 0c fig. 2-b. x: time (min), y: pressure (bar), temperature 130 0c 0.733 0.708 0.683 0.657 0.631 0.579 0.547 0.514 0.482 0.449 asem hassan mohammed al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 141153(2016) 147 fig. 2-c.x: time (min), y: pressure (bar), temperature 147 0c 5.3. glucan degradation glucan pretreatment yields were above 90 g glucan recovered/100 g glucan in raw biomass, for all operation conditions as shown in the figures (3-a,3-b,3-c),these figures show the relationship between the oxygen pressure and time of pretreatment on the glucan yield by holding the temperature at 113, 130 and1470c. the color gradient, unlike lignin degradation, these figures which begins with orange color indicates the highest desirableglucan yield , and end with dark blue represents the lowest undesirable glucan yield, furthermore degradation within progress of pretreatment at increasing temperature and/or pressure. the highest observed glucan degradation was recorded for the pretreatment at1600c and 13.5 bar 3.5 h (90.47 g glucan degraded/g glucan in raw biomass) while the lowest glucan degradation was at 1130c, 9.2 bar and 2 h, and its yield was 99.3 g of glucan remaining/100 g glucan in the raw biomass. generally, glucan degradation was very small in comparison with lignin and hemicellulose, because as soon as the pretreatment started, some rapid peeling degradation of glucan occurs. fast stopping reactions follow and degradation of remaining glucan depends on the generation of newly accessible reducing-end groups [1]. 0.958 0.966 0.982 0.974 0.949 0.417 0.378 0338 0.298 0.258 fig.3a, x: time (min), y: pressure (bar), temperature 113 0c fig.3b, x: time (min), y: pressure (bar), temperature 130 0c 0.965 0.957 0.949 0.942 0.934 asem hassan mohammed al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 141153(2016) 148 fig. 3-c.x: time (min), y: pressure (bar), temperature 147 0c 5.4. xylan degradation in a case of xylan, the degradation was much faster than glucan. at 1130c, 31.5 bar and 3.5 h the yield was above 75 g xylan recovered/100 gxylan in the raw biomass, whereas the highest xylan degradations were observed for the pretreatment at 1600c, 13.5 bar and 3.5 h, and 1470c, 17.8 bar and5 h, the yield was 42 g of lignin remaining/100 g lignin in the raw biomass.hemicellulose degradation is important, because the contribution of this carbohydratepolymer to the total carbohydrate yield is potentially significant. theaverage yield of xylan degradation for all our conditions was approximately close to the average yield of lignin degradation (0.536 and 0.511, respectively). similar tolignin and cellulose degradation, xylan degradation was triggered by higher temperaturesand oxygen pressures. furthermore, xylan degradation was much more significantthan glucan degradation and behaves very similar to lignin degradation because of covalent bonds between hemicellulose and lignin in the cell wall [10]. generally, lignin content and crystallinity have major effects on biomass enzymatic digestibility, whereas acetyl content has a minor impact [7, 11]. therefore, pretreatments that can significantly remove lignin or reduce crystallinity were particularly effective by taking into consideration the balance between the lignin removal and carbohydrate degradation. 6. enzymatic hydrolysis 6.1. materials and methods at the end of oxidative short-term lime process, the pretreated biomass was neutralized, wash, and stored wet in the freezer at-200c. the substrates used in enzymatic hydrolysis are raw biomass (untreated) and pretreated-neutralizedwashed willow wood. the materials used in enzymatic hydrolysis were: (cellic ctec2 cellulase) which was providedby novozyme, deionized water, sodium citrate buffer 0.05-m (ph 5) and sodium azide 10.0 g/l to prevent microbial contamination, the final volume was 10 ml and the incubation period of enzymatic hydrolysis was 72 h. enzymatic hydrolysis was performed in 20 ml erlenmeyer flasks or scintillation vials (20 ml) in a static incubator (oven) set at 50 0c ±1 which contains multiple place magnetic stirrers inside. the temperature was set at 50 0c and the speed of magnetic stirrers at 200 rpm. the mixing process must be sufficient to keep solids in constant suspension for a period of 72 h, where most of glucan or xylan is hydrolyzed to their sugars from the solid pretreated biomass. the samples that subjected to enzymatic hydrolysis were withdrawn after 3 days and then boiled for 15 minute to denature the enzymes to prevent further hydrolysis. after that the samples were centrifuged at 4000 rpm for 20 minutes. then the samples were diluted by using deionized water to get sugar concentration in the range of carbohydrate standard concentration. the required quantity of cellulase enzyme was calculated based on the amount of glucan in the raw biomass and the desired enzyme loading. the suggested enzyme trial dosage levels for initial investigation of a substrate were 30.0%w/w (g enzyme/g cellulose) and the amount of biomass to be weighed was calculated based on the moisture content and the glucan content to provide 0.1 g glucan for the reaction. the samples were filtered through a 0.2µm filter and subjected to glucose analysis by using hplc analysis by using phenomenex rezex(rpm pd+2) column, and ri detector. the measured sugars of hydrolysis samples were used to indicate biomass digestibility. all enzymatic hydrolysis experiments were conducted duplicate an dall steps of enzymatic hydrolysis process were based on(nrel). 0.950 0.943 0.936 0.929 0.921 asem hassan mohammed al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 141153(2016) 149 6.2. results and dissection it has been using the same statistical method which previously used in the pretreatment to find the relationship between overall total sugar yield(yt s ) and pretreatment conditions, in order to find the best overall yield of totalsugar ( yt s ). table (4) shows the results of different types of yields. table 4, different yields of overall process (pretreatment and enzymatic hydrolysis). ex.no yg% y g% avar.y g yt g% glucan. g yx% y x% y t x% xylan. g yt s% 1 92.00 0.897 0.903 83.076 3.873 43.317 0.840 36.386 0.688 0.400 1 0.910 2 93.27 0.942 0.950 88.606 4.131 55.467 0.955 52.971 1.002 0.45 2 0.955 3 94.00 0.955 0.940 89.770 4.185 43.613 0.976 42.566 0.805 0.437 3 0937 4 94.34 0.999 0.994 93.700 4.371 50.185 0.992 49.784 0.943 0.466 4 0.988 5 99.40 0.815 0.820 81.200 4.800 68.200 0.909 62.000 1.173 0.436 5 0.825 6 97.20 0.905 0.914 88.841 4.141 60.961 0.920 56.084 1.061 0.456 6 0.922 7 97.20 0.955 0.950 92,340 4.305 53.200 0.950 50.536 0.956 0.461 7 0.915 8 95.12 0.970 0.972 92.456 4.310 55.867 0.990 55.308 1.047 0.470 8 0.973 9 90.47 0.965 0.971 87.435 4.076 40.623 0.990 40.217 0.761 0.424 9 0.977 10 93.00 0.990 0.990 92.070 4.292 49.181 0.990 48.690 0.868 0.452 10 0.991 11 92.77 0.970 0.972 90.172 4.204 48.779 0.945 46.096 0.872 0.445 11 0.975 12 98.80 0.784 0.979 77.000 4.590 78.610 0.909 71.456 1.353 0.434 12 0.774 13 94.00 0.930 0.925 86.025 4.010 59.323 0.920 48.577 1.033 0.442 13 0.920 14 98.87 0.904 0.918 87.714 4.090 61.800 0.956 59.087 1.118 0.457 14 0.931 15 94.65 0.950 0.950 87.714 4.205 52.720 0.953 50.242 0.951 0.448 15 0.950 16 94.75 0.939 0.938 89.065 4.152 53.249 0.942 50.160 0.950 0.445 16 0.937 17 94.50 0.949 0.951 90.000 4.196 54.094 0.950 51.390 0.973 0.452 17 0.953 18 94.70 0.950 0.950 90.000 4.196 54.147 0.940 50.898 0.963 0.450 18 where: yg=pretreatment yield of glucan (g glucan recovered/100 g glucan in raw biomass) yg=hydrolysis yield ogglucan (g glucan hydrolyzed/ g glucan in treated biomass) yt g=overall yield glucan (g glucan hydrolyzed/100 g glucan in raw biomass) yx=pretreatment yield of xylose(g xylan hydrolyzed/100 g xylan in raw biomass) yx=hydrolysis yield of xylan(g xylan hydrolyzed/ g xylane in treated biomass) yt x =overall yield of xylane (g xylan hydrolyzed/100 g xylan in raw biomass) yt s =overall yield of total sugar (glucan+ xylan)/ g raw biomass) glucan (g) and xylan (g) representquantity of glucan and xylan are hydrolyzed after pretreatment and enzymatic hydrolysisfor total raw biomass (11.40 g). generally, for all samples that underwent to pretreatment conditions (pretreatment time, compressed oxygen, and temperature) have strongly affected through biomass enzymaticdigestibility. during enzymatic hydrolysis, glucan and xylan converted toglucose and xylose and trace of mannose. since the enzymatic hydrolysis operation have took place inthe separate stage, thus, the recommended pretreatment conditions were chosen based on the glucan and xylan overall yield (i.e., yields after asem hassan mohammed al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 141153(2016) 150 the combined operations of pretreatment and enzymatic hydrolysis).the following equation represents the relationship (polynomial equation) between overall yield and pretreatment condition, that was driven from statistical model. �� � = +0.06431 + 2.51342� − 003 × �� + 0.012445 × �� + 0.093164 × �� − 5.33365� − 5 × ���� − 5.914� − 4 × ���� − 1.6439� − 3 × ����. (r=0.83, p-value≤ 0.001) …( 4) equation (4) includes all the terms regardless of their significance which was more than 0.95.the highest value recorded of practical experiments of overall yield of glucan was 93.700 g glucan hydrolyzed/100 g glucan in raw biomass (equivalent to the hydrolysis yield of 99.00 g glucan hydrolyzed/100 g glucan in treated biomass) also it had the overall total sugar yield 0.466 under pretreatment condition: 1480c, 17,8 bar and 2.06 h. the experimentally calculated value of overall total sugar yield was almost close to predicted optimum value (0.468). this point represents the optimum point of overall process. through the study of the relationship between the enzymatic hydrolysis and the residuallignin content, it was noticed, that the enzymatic hydrolysis at 147.80c ,17.8 bar and 5 h was 90.30%, nevertheless the lignin content of the sample was lower than the rest samples but it has lower enzymatic hydrolysis. to realizethis phenomenon, cellulase enzyme that was supported from novozyme cop. is a rather friendly with lignin at certain level of lignin. this type of enzyme contain gh61proteins were able to enhance enzymatic hydrolysis of glucane which hasa certain level of lignin, unlike of pure glucane , none of the gh61proteins were able to enhance the hydrolysis of pure glucan like filter paper. this lack of enhancement was also shown with other pure cellulose substrates such asavicel, phosphoric-acid swollen cellulose and carboxymethyl cellulose. proteins gh61are capable to enhance hydrolysis of acid pretreated corn stover and as it is well known that the samples which is conducted with acid pretreatment have large amount of lignin [12]. this mean that lignin content at 147.8 0c, 17.8bar and 5 his lower than lignin content which enhance cellulase activity. also we noticed the highest residual concentration of lignin that gives full hydrolyzed for glucan was approximately 0.15 g lignin remaining /g of pretreated biomass or lignin selectivity is equal 0.15 residual lignin /g of pretreated biomass, which is at 147.80c , 17,8 bar and 2.06h. this point is very important because of going on more than this point will increasecarbohydrate degradation without any benefit, and less than this point of lignindegradation will not get the full hydrolysis. as shown in figure (4), it is clear that the optimum point of total sugar yield (bold point) will be terminal at temperature 147.80c, oxygen pressure 17.8 bar and time 2.06 h, or in other mean this point lie on the circumference of circle. to complete whole region of my interested, the study examined the area around the previous point within temperature range 147.8-1600c, oxygen pressure range 21-17.8 bar (absolute) and pretreatment time range 1-2 h. extra experiments have been done in this region for points that have the potential to be a more optimal point with considering to reduced pretreatment time less than two hours and at the same time increasing the oxygen pressure and temperature. fig. 4. points of a central composite circumscribed design with three input parameters. asem hassan mohammed al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 141153(2016) 151 table (6) shows that the best overall total sugar yield (yt s) was (0.486) at 1480c, 17,8 and time 1.33 h (80 minutes) and it was the optimum condition. also it can be noticed that most of the values of overall total sugar yields in this table were approximately close. table 6, the yields for extra experiments. the effect of substrate concentration on the enzymatic hydrolysis process was studied in this research, to find the best high substrate concentration, the experiments were carried out at different concentrations (10, 20, 50 g/l) with the same concentration ofenzyme loading (30.0%(g enzyme/g cellulose). glucose, xylose and mannose were measured after end of hydrolysis by hplc device. the highest concentration of substrate that can be obtained with the same digestion efficiency of 10 g/l was 50 g/l. this result was compatible with other research [7]. also the concentration of substrate more 50 g/l was noticed will not be suitable for enzymatic hydrolysis because the mixture will be heterogeneous. in the previous experiments in this research, excess enzyme loading was used for eliminate any interference related to amount of enzyme and then to determine the lowest enzyme loading that gives same digestion efficiency of 30.0%w/w (g enzyme/g cellulose) at 50 g/l substrate concentration for points at (1480c, 17,8 and time 1.33 h) and (1550c, 21bar and time 1.25 h). three type of enzyme loading (15.0%, 10.0%, 5.0% w/w (g enzyme/g cellulose) were tested. the lowest enzyme loading gives high digestion efficiency at (10.0%w/w (g enzyme/g cellulose) for both points. at the final stage of this research, the lowimpact variables such as lime loading and particle size were studied in order to reduce both the consumption of lime and energy comminution of biomass. the best lime loading was 0.26 g lime/g raw dry biomass and the best particle size was between 2-3 mm. 7. conclusion for high-lignin biomass, such as willow wood and poplar wood, oxidative shorttermlime pretreatment was very effective for digestibility by enzymatic hydrolysis. generally, oxidative short-term lime pretreatment showed less sugar degradation with more lignin removal. glucan was preserved much more than xylan because xylan degradation was more related to lignin removal and deacetylation. the most important pretreatment glucanand xylan yield which gives very high digestibility at 147 0c, 17.8 bar and 1.33 h (80minute), and 155 0c, 21 bar, 1.25 h (75 minute) also they have lignin content lies between 15-16.5%. a lower pretreatment yield of glucan and xylan were observed at 147.8 0c, 17.8 barand 5h (0.927 and 0.422, respectively) and 160 0c, 13.5 bar, 3.5 h (0.904 and 0.420, respectively). this mean, the pretreatment temperature is more dominant than pressure and pretreatment time. at temperature 100 0c, 13.5 bar and 3.5 h, the enzymatic hydrolysis of glucan was low (78%), because of poor delignification ( 22% lignin content). a lonely criteria used in enzymatic hydrolysis is that the process is performing on 3-days to avoid the effect of glucan crystallinity. accordingly, the lignin content was considered as the crucial factor. this study found, that there are two of optimum points are: (1) 147.8 0c, 1.33 h, 17.8bar (absolute), 0.26 g ca(oh)2 and 15 g water/g raw biomass (2) 155 0c, 1.25 h, 21.0bar (absolute), 0.26 g ca(oh)2 and 15 g water/g raw biomass. the overall glucan and xylanyields(i.e., glucose and xylose recovered after both pretreatment and enzymatic hydrolysis, and expressed as equivalent glucan and xylan) that obtained in the first are:0.96 g glucan hydrolyzed/100 gglucan in raw biomass, and 0.63 g xylan hydrolyzed/100 gxylan in raw biomass, in the second point are:0.94 g glucan hydrolyzed/g glucan in raw biomass and 0.52 g xylan hydrolyzed/100 g xylan in raw biomass, respectively. pretreatment conditions yields ex.no temperature, c0 pressure, bar time, h yg% y g% y x% y x% y t s% 19 148 17.8 1.33 96.00 0.98 63.18 0.99 0.48 20 150 21.0 1 95.40 0.95 58.00 0.95 0.46 21 155 21.0 1.25 94.70 0.99 52.40 0.99 0.47 22 160 21.0 1 94.70 0.98 54.20 0.96 0.46 asem hassan mohammed al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 141153(2016) 152 8. references [1] rocio sierra, mark thomas h." selectivity and delignification kinetics for oxidative and non-oxidative lime retreatment of poplar wood, part iii: longterm", biotechnology progress, vol. 26, issue 6, pp. 1685-1694, 2010 [2] alan g. williams, ian m. m."studies on the production of saccharinic acids by thealkaline treatment of young grass and their effectiveness as substrates for mixed rumen microorganisms in vitro". : sci food agric., vol. 33, pp. 21-29, 1982 [3] mark t. holtzapple, m. ross s.lee. murlidhar n. chang-lee c. lee s. adelson w. k. ; gaskin, d.," biomass conversion to mixed alcohol fuels using the mixalco process", applied biochemistry and biotechnology, vol. 79, pp. 609-631. 1999 [4] mosier n, dale b elander r lee yy holtzapple m ladisch m." features of promising technologies for pretreatment of lignocellulosic biomass".bio resource technology, vol. 96, pp. 673-686, 2005 [5] chang vs, holtzapple m.," lime pretreatment of switchgrass". applbiochembiotechnology, vol. 63/65, pp. 319, 1997 [6] rocio, sierra r.," long-term lime pretreatment of polar wood". aichejournal , vol. 57, issue 5, , pp. 1320-1328, 2005 [7] zhu, li.,"fundamental study of structural features affecting enzymatic hydrolysis of lignocellulosic biomass". texas a&m university, diss., august 2005 [8] b. hames, r. ruiz, c. scarlata, a. sluiter, j. sluiter, and d. templeton" preparation of samples for compositional analysis ". laboratory analytical procedure (lap),issue date: 9/28/2005.technical report, january 2008. [9] chang, nagwani m. holtzapple m" lime pretreatment of crop residues:bagasse and wheat straw". applied biochemistry and biotechnology.vol 74. issue 3, 1998. [10] helm, r. f., lignin-polysaccharide interactions in woody plants". lignin: historical, biological, and materials perspectives. chapter 5, pp. 161-171, 1999. [11] odwyer, jonathan p.," developing a fundamental understanding of biomass structural features responsible for enzymatic digestibility". , texas a&m university. phdthesis, diss., 2005 [12] merino s.t., cherry j." progress and challenges in enzyme development for biomass utilization". advances in biochemical engineering/biotechnology, vol. 108, pp. 95-120, 2007 ح�� ���� �� � ��� 4، ا���د��12 � ا���ارز�� ا������� ا��� ،153-141 )2016( 153 ��� � � �ز$� ا�& �%�$�ت "�!� ���% )��$' ا���اد ا� ***,�ر*+ $�ر-� � �� **,�ا*+ !��*( *�� ح�� ���� �و�� *����ت ا! $�� /()' ا!&%� 89-اد /ا!6�0/� ا!%45�� ا!+0 /123/., %+!+* **' ***�:!��> /ا!6�0/� ا!5 %+!+*�� / ا! ;�� ا!:!=9 asemh20052@yahoo.com :اa! 5=و@? ا!<=�-* frank_jürgen.methner@tu.berlin.de : اa! 5=و@? ا!<=�-*** � ا��. +;��ت ا!1 داci ز�� ھ? $�;�� f/<� ان $�;�� ا!c;d5 ا�b@a�? !;�+اد ا!; %+3;��b@aذ ا+k@ <0 l%�, ?5!ز�� وا+;��� !;�+اد ا!; %+3;; �m>(9 ا!<%�� ا!. ��ا! 5;� >no!ا ,' . اpھ �%:d9 ?qر��5iم ا+�(!��ا! 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(tرو-��+�� /ھ^ �;5t 'd �مi(ء ا��� ا!��t c:0 =�yz5!ا �;�;) c0:;1 !;/+ا�وف ا!=w!أن ا ��t ، k@�t �0-o5(�!١٥ ) ء�0 'd / م�i ��+�^ �;5t 'd (>d!6' اd!نوا�t mno;! ?>� �0 <��? $;1 و. 0' ٣ 9٢��b@vا c;d5!ا ���@k ا!w=وف ا!�:;1 !/�;t uqو +d%!ا?,aا : b�;��� ا@�b' ا!);�t)٠.١ 'd /م�o!ا ��+�d!ا! 5;� ا ?q ن�t+;t 'd( ، ��+�d!ا! 5;� ا b�t=,٥٠ 'd /i0> ٧٢]ل !5= و �$�3 c;d5!ا ،?���b@vا ��ن9/-ھt aا-f��ا!/!��* ��;�/;?��b@aا c;d5!�6 ا!��+�� ا!�/d!1 !; 5;� ا;$ +d%!ا ?!��ن ٩٦.٠٠: ا!5t+;* 'd /م، و ١٠٠�o!ا ��+�d!ا! 5;� ا ?q ن�t+;* <0 'dز�]ن ٦٣.٠٠ 'd /م ١٠٠�o!ا ��+�d!ا! 5;� ا ?q ز�]ن 'd. نجوى واسر al-khwarizmi engineering journal,vol. 11, no. 4, p.p. synthesis and characterization of nano najwa saber majeed* * department of chemical engineering ** department of student affairs and authentication (received 2 abstract nano-crystalline zsm-5 zeolite was synthesized by hydrothermal method using chelating agent and two gel compositions:compositionɪ:al 2o3:86sio 10na2o:2.6trien:2626h2o.study of hydrothermal reaction factors on characteristics of nano carried on ,among them are crystallization temperature, crystallization time and concentrati solution. synthesis was accomplished in ptfe lined autoclave ( reactor ) . the product were characterized by x diffraction ( xrd ),atomic force microscopy ( afm ),scanning electron microscopy, fourier transform infrared ( ftir ) and brunauer-emmet-teller (n2 absorption synthesized zeolite increase with increasing crystallization time and temperature. afm results indicate that a nano level of about 50nm was reached for "particle average diameter". "1080,800,550,450 cm-1" have been clearly obtained, (tpaoh) solution concentration on crystallinity and keywords: crystallization , template, synthesis, 1. introduction zsm-5 is a member of mfiwith high si/al ratio from 10-100+.it is a zeolite with three dimensional channels, and it has two kinds of channels, straight channels with pore opening of 0.54nm x 0.56nm and sinusoidal channels with a pore opening of 0.51nm x 0.55nm[1]. zsm-5 has been given a great attention by researchers because of its splendi specifications concerning thermal stability, high surface area, strong acidity, and presence of nano-spaces ,the sizes of intra-crystalline pores and nanospaces are nearly the same as molecular diameter of light hydrocarbons [2]. strong acid sites exist on the nanoporous surfaces enable the zeolite to be used as shape selective "catalyst" especially in petroleum and petrochemical industries, such as isomerization, fluid catalytic cracking and also in adsorption processes[2] . the crystal size of zeolite is much larger than the khwarizmi engineering journal,vol. 11, no. 4, p.p. 819 (2015) synthesis and characterization of nano-crystalline zsm najwa saber majeed* asir abduljabbar alnaama** mical engineering/ college of engineering/ university of baghdad ** department of student affairs and authentication/ university of bagdad email: dr.najwa_saber@yahoo.com email: a.alnaama53@gmail.com (received 23 march 2015 ; accepted 7 may 2015) 5 zeolite was synthesized by hydrothermal method using chelating agent and two gel :86sio2:5.5tpa:12.7na2o:3.4trien:3320h2o.composition o.study of hydrothermal reaction factors on characteristics of nano carried on ,among them are crystallization temperature, crystallization time and concentration of template ( tpaoh ) solution. synthesis was accomplished in ptfe lined autoclave ( reactor ) . the product were characterized by x diffraction ( xrd ),atomic force microscopy ( afm ),scanning electron microscopy, fourier transform infrared ( ftir absorption-desorption isotherm).sem and xrd results indicate that crystallinity of synthesized zeolite increase with increasing crystallization time and temperature. afm results indicate that a nano was reached for "particle average diameter". ftir results showed that the required peaks near have been clearly obtained, furthermore the results showed strong effect of template (tpaoh) solution concentration on crystallinity and decreasing of particle size towards nano crystallization , template, synthesis, nanocrystalline, zsm-5 zeolite. -zeolite family 100+.it is a zeolite e dimensional channels, and it has two kinds of channels, straight channels with pore opening of 0.54nm x 0.56nm and sinusoidal channels with a pore opening of 0.51nm x 5 has been given a great attention by researchers because of its splendid specifications concerning thermal stability, high surface area, strong acidity, and presence of crystalline pores spaces are nearly the same as molecular diameter of light hydrocarbons [2]. strong acid ist on the nanoporous surfaces enable the zeolite to be used as shape selective "catalyst" especially in petroleum and petrochemical industries, such as isomerization, fluid catalytic cracking and also in adsorption processes[2] . the ite is much larger than the micropore size ,and this will result in a low diffusion rate of reacting hydrocarbon molecules leading to low mass transfer, and consequently lower reaction rate, low selectivity of intermediates and coke formation followed b short catalyst life time. proposed solutions have been implemented, the first one was the formation of meso crystal structure of the zeolite, the second solution was to prepare nano-sized crystalline zeolite, so that the diffusion path for reacting molecules will be decreased as crystal size decrease these two factors are effective in improving catalytic activity[2]. different methods and procedures have been utilized to synthesize zsm hydrothermal crystallization of reactive alumina silicate gels[1,3,4,5,6,10,11,17]. the product properties are highly affected by many factors such as alumina and silica sources[4,11],si/al al-khwarizmi engineering journal (2015) crystalline zsm-5 zeolite asir abduljabbar alnaama** university of baghdad university of bagdad 5 zeolite was synthesized by hydrothermal method using chelating agent and two gel o.compositionɪɪ:al 2o3:68sio2:5.4tpa: o.study of hydrothermal reaction factors on characteristics of nanosized zsm-5 has been on of template ( tpaoh ) solution. synthesis was accomplished in ptfe lined autoclave ( reactor ) . the product were characterized by x-ray diffraction ( xrd ),atomic force microscopy ( afm ),scanning electron microscopy, fourier transform infrared ( ftir desorption isotherm).sem and xrd results indicate that crystallinity of synthesized zeolite increase with increasing crystallization time and temperature. afm results indicate that a nano-sized ftir results showed that the required peaks near furthermore the results showed strong effect of template decreasing of particle size towards nano-size level. micropore size ,and this will result in a low diffusion rate of reacting hydrocarbon molecules leading to low mass transfer, and consequently lower reaction rate, low selectivity of intermediates and coke formation followed by a a methodology of two proposed solutions have been implemented, the first one was the formation of meso-pores in the crystal structure of the zeolite, the second solution sized crystalline zeolite, so the diffusion path for reacting molecules will be decreased as crystal size decrease these two factors are effective in improving catalytic different methods and procedures have been utilized to synthesize zsm-5 which involve a rystallization of reactive alumina silicate gels[1,3,4,5,6,10,11,17]. the product properties are highly affected by many factors such as alumina and silica sources[4,11],si/al najwa saber majeed al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 819(2015) 9 ratio [4,5,11,14],template [1], crystallization time [1,7] and crystallization temperature [1,4,7,8,9]. r. karimi et al[1].used hydrothermal synthesis by stainless steel autoclave lined with ptfe , they investigated the effect of crystallization temperature and time also studies the effect of the type of organic structure directing agent (osda) on the synthesized zeolite , a nano level sized of zsm-5 has been produced with high crystallinity at temperature range of 170-180 and 120h for crystallization time, .they found that the template (osda) content has a great effect on zsm-5 properties , a ratio of 0.058 for tpaoh/si was optimum. m.abrishamkar et al [3] followed a clear solution method under atmospheric pressure using tpaoh as template, aluminum isopropoxide as alumina source , teos as silica source with naoh and h2o as mineralizer and solvent respectively , they reported a new path for producing nano-crystalline zsm-5 zeolite. r. mohamed et al [4] studies the effect of the silica source on the crystallinity of nano sized zsm-5 zeolite ,they concluded that crystallinity of zsm-5 produced is increased in the following order colloidal silica < teos < fumed silica. r. mohammed et al[7] studies the influence of the crystallization time on the synthesis of nano sized zsm-5 , they found that a time of crystallization of 45h gave the highest crystallization with 55.6 nm for average particle size and the bet surface of 360 m2/g , using 20wt% tpaoh as template (osda). in this research work tetrapropyl ammonium hydroxide (tpaoh) was used as template .a detailed parameter study to get the desired properties in the final zeolite product has been accomplished including crystallization time ,temperature ,gel composition ,template solution concentration and chelating agent. 2. experimental 2.1. technical procedure tetraethylorthosilicate (teos-sigma aldrich ) was used as silica source, aluminum is opropoxide (aip-sigma aldrich) as alumina source, tetrapropyl ammonium hydroxide (tpaoh) as template, sodium hydroxide as alkaline agent, triethylenetetramine as chelating agent, and deionized water as solvent. nano-sized zsm-5 zeolite was synthesized using twin stainless steel autoclaves lined with polytetraflouroethylene (ptfe), and by hydrothermal reaction of silica source with alumina source in presence of tpaoh as template and trien as chelating agent .two compositions was studied and chosen, the first one with silica to alumina ratio si/al is 86, and the second is with si/al=68.the preparation procedure was kept the same, the differences are in the amount of alumina source(aip) and template (tpaoh). composition ɪ : al 2o3:86sio2:5.5tpa:12.7na2o:3.4trien:3320h2 o. composition ɪɪ: al 2o3:68sio2:5.4tpa:10na2o:2.6trien:2600h2o 2.2. preparation composition i the template tpaoh (2.2g) and teos (36g) were mixed with (40ml) deionised water for 1h of stirring. trien (1ml) was added , naoh (2.05g) was dissolved in 40ml deionised water and added also to make solution 1. aluminum is opropoxide (aip) 0.82g was added to 40ml deionised water and stirred for 1h to make solution 2. the resulting mixture(solution 2 ) was added dropwise to (solution 1) with vigorous stirring (500rpm) in mechanical stirrer for 120min. the resulting gel was poured into a stainless steel autoclave lined with ptfe(polytetraflouroethylene), the volume of ptfe insert is 200 ml and were filled to about 65% of its inside volume .a stir bar was placed inside the ptfe insert for stirring purpose. the sealed autoclave was equipped with electric heating jacket providing 500w and thermocouple t-type, also pressure indicator for measuring the autogeneous pressure. an electronic board with (pid) to control the temperature inside the autoclave during the hydrothermal reaction ,twin autoclaves were used as shown in fig.1. 2.3. preparation of composition ii the same procedure except that the amount of "template" tpaoh used was (2.9g) and the amount of alumina source (aip) was (1.025g) .for both compositions and after collapsing the desired time at specific temperature ,the autoclave was left to cool overnight and the solid product was filtered, washed with distilled water many times and finally with ethanol, then the product left to dry at 110 ̊c overnight. then the material was calcined at 550 ̊c for 5h with temperature ramp 1 ̊c/min. the hydrogel compositions and crystallization conditions ( time& temperature ) of hydrothermal synthesis for various samples are tabulated2in2table2. najwa saber majeed al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 819(2015) 10 fig. 1. twin autoclaves lined with ptfe. najwa saber majeed al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 819(2015) 11 table .1 sample conditions. table.2, parameters of samples. si/al wt% tpaoh composition crystallization temp.0c crystallization time ,h sample 86 10 ɪ 140 24 s1 86 10 ɪ 150 72 s2 86 10 ɪ 160 72 s3 86 20 ɪ 160 72 s4 86 40 ɪ 160 72 s5 86 40 ɪ 160 96 s6 86 40 ɪ 170 96 s7 86 40 ɪ 175 80 s8 68 40 ɪɪ 150 48 s9 68 40 ɪɪ 150 72 s10 68 40 ɪɪ 150 96 s11 68 40 ɪɪ 160 48 s12 68 40 ɪɪ 160 72 s13 68 40 ɪɪ 160 96 s14 68 40 ɪɪ 170 48 s15 68 40 ɪɪ 170 72 s16 68 40 ɪɪ 170 96 s17 68 40 ɪɪ 180 48 s18 68 40 ɪɪ 180 72 s19 68 40 ɪɪ 180 96 s20 crystallinity% pore volume cm³/g s.surface m²/g ave.particle.diam.,nm sample 78 0.111 155.9 84.7 s1 98.4 0.1477 229.8 76.3 s2 110 0.15181 259.7 80.2 s3 88.4 0.2007 347 73.6 s4 104.7 0.20721 355.1 79.2 s5 90.3 0.2022 345.88 74 s6 82.8 0.225 380.9 79.4 s7 95.5 0.192 334.13 74.4 s8 77 0.2016 334.5 84.43 s9 99.5 0.1878 336.4 71.98 s10 88.8 0.18405 335.86 90.8 s11 84.4 0.2117 360.4 85.08 s12 92.9 0.1959 351.9 91.2 s13 96 0.206 351.76 65.9 s14 114.4 0.2239 365.1 50.8 s15 100 0.1997 336.1 81.68 s16 98.8 0.18852 322.39 60.5 s17 102 0.1967 332.8 86.8 s18 107.4 0.1920 303.96 63.4 s19 95.2 0.18997 327.53 51.9 s20 najwa saber majeed al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 819(2015) 12 3. characterization the xrd patterns of zsm-5 zeolite were determined using a d2 phaser/ bruker (germany 2010) using cukα radiation nickel filter (λ=1.54a).data were collected within the 2ɵ range of 2̊ and 50̊ with a 0.02̊ 2ɵ-step and 0.5s per step ( 30kv and 10ma )x-ray diffraction was implemented to check the required pattern of zsm-5 and its crystallinity. fourier transform infrared (ftir) by shimazdu-ira affinity1,using kbr wafer 1% wt zeolite and 99% kbr to check and record the peaks at specified wave lengths corresponding to zsm-5 in the range of 400-4000 cm-1 wave number. the morphology of zsm-5 zeolite was studied by scanning electron microscopy using te scan,vega ɪɪɪ lm,czech. the particle size and morphology on nano-level size were ,determined by atomic force microscopy using an aa3000/angstrom advance inc, usa ,scanning probe microscope(spm) gave granularity cumulation distribution and surface roughness. table 2 shows parameters of samples, average particle diameter measured by , in which the increase in crystallinity is only from 99.5% to 107.4%, in averaging the value of (afm),specific.surface(bet), pore volume, and crystallinity (xrd) for both compositions.bet surface and pore volume for all samples were measured by surface area analyzer/q surf series/italy ,two samples s7 and s20 was repeated by micrometrics asap 2020/usa. bet surface is based on bet theory (brunauer . emmet and teller) which described five basic adsorption isotherms . but iupac classification added one more adsorption isotherms .bet theory is an extension of the langmuir theory (monolayer adsorption model) to the multi adsorption model. adsorption can be defined as the adhesion of atoms or molecules of gas to a surface , the amount of gas adsorption depends on surface area. gas pressure, temperature and strength of interaction between the gas and solids . nitrogen is usually used in bet surface analysis because of its purity , strong interaction with most solids and availability bet equation for determining surface area in its simplest form. 11111111111111111111 st=k(1-p/po)*va where st=total surface area of sample being analyzed k=a constant for nitrogen , assuming stp condition=4.03 p/po=0.294 for gas mixture of 30% n2/70% he va=volume of gas (n2) adsorbed each cubic centimeter of n2 adsorbed (then desorbed) by the sample is equivalent to total surface area (st) of 2.84 m2 , the specific surface is found by dividing st by the weight of the sample in the cell in grams the complex form of bet equation. 1111111111111111111111111111 � �(����) = � � + �� � � ���� [11,19] p=pressure , kpa po=saturation pressure , kpa v=total volume of gas adsorbed , cm3 vm=volume of gas absorbed in monolayer , cm3 c=constant and related to the heart of adsorption ���� ������ = � ��� �� � !" [11] v=volume of adsorbed gas mg=molecular wight ρg= gas density for bet surface area analysis a mixture of nitrogen balance helium is passed through the reference channel of the thermal conductivity detector(tcd)to the sample housed within a flowthrough glass cell and finally into the tcd analytical channel the signal produced by the tcd detector is collected by the microprocessor control board. the procedure starts with the degassing of the sample with the carrier gas at the programmable temperature when the sample is dried , the operator simply transfer the sample holders to the analytical ports and fit them into place. pressing the start button will automatically raise the liquid nitrogen flask carriage initiating the analysis... fig. 2. bet surface area analyzer. najwa saber majeed al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 819(2015) 13 fig. 3. aspa 2020 accelerated surface area and porosimetry system astmd3663, astmd4222, astmd4365, astmd4641. 4. results and discussion 4.1. crystallization temperature the most important factor in the synthesis of zeolite is crystallization temperature, so a set of samples were prepared for both compositions i & ii ranging from 140 ̊c-180 ̊c as shown in table 2, the results show a strong dependency of crystallinity on temperature and these results coincide with previous work[1,4,11]. comparing sample s9(150 ̊c,48h) with s18(180c̊,48h) it can be noticed that the crystallinity increased from 77% to 102% , this increase of crystallinity would be less as time of crystallization increase to 72 when comparing sample s10(150̊c-72h) and s19(180̊c,72h). the average crystallinity with temperature (see table 3), showed an increase in the average value of crystallinity from 88.4% at 150̊c to 91% at 160̊c and 104.4% at 170c̊, keeping almost the same level at 180c̊ , indicating that the crystallinity, reached its optimum value around 170-180c , figs.3 and 4 are xrd patterns and sem micrographs of zsm5 products the effect of temperature on average particle diameter and the nano-level size was observed and a tendency to have a decrease in average particle diameter as temperature is increased, and particle diameter decreased from about 82nm at 150̊c to 67nm at 180c̊ (see table 3), these results of nanolevel size are associated with a high crystallinity degree, support the hypothesis and results revealed recently by lupulescu and rimer[19], which suggested a non-classical pathway of zeolite crystallization by the presence and gradual consumption of nano-particles, while most crystals grow through classical means (the addition of atoms or molecules to the crystal). sem images show that samples which were prepared at temperature 150 ̊c has amorphous phase which coincide with average results of xrd patterns and crystallinity (88%), and crystallized in spherical form,but for samples prepared at 170 and 180 ̊c crystallized mostly in orthorhombic shape crystals. 4.2. crystallization time to study the effect of this important factor, a series of samples was prepared using gel composition ɪ, and composition ɪɪ . xrd patterns (figs.3) at different temperatures (150,160,170,180 ̊c) , show that zsm-5 phase is the only one obtained in all experiments and the peak at 2ɵ=7-9 and 2ɵ=22.5-24.5 are typical for zsm-5[13]. the crystallinity of samples show a tendency to increase due to increase in crystal nucleation and growth rate , as the time increase in temperatures range of 150 & 160 c but for temperature 170 and 180 c the crystallinity increased up to 72h. comparing sem images of s19 (72h,180 c) with s20 (96h,180 c) show that the increased crystallization time cause to have a lower crystallinity and beginning of losing the orthorhombic shape crystals to spherical. but a little decline observed in crystallinity when time increased above 72h, the crystallinity begins to decrease slightly , this behavior can be explained by the cause of a reverse process of recrystallization occurs leads to this declination , and it seems that the template(tpaoh) begins to lose its performance at higher temperature when the time of crystallization increased above 72h, the reports of afm showed that the nano-sized level of crystalline zsm-5 are influenced by temperature and time and as shown in tables 2 and 3 and fig.2 . the spectra of (ftir) for synthesized samples at various crystallization times and temperature are showed in fig.5 the findings show that the bands near1085cm1(internalasymmetricstretch), 799cm-1(external symmetric stretch),546 cm-1(double ring vibration) and 452 cm-1(t-o band) and the formation of zsm-5 phase only.the peak near 550cm-1 is attributed to the fivemembered ring of the zsm-5 zeolite structure (pentasil)[17]. the evidence for getting nano-sized level of zsm-5 najwa saber majeed was the peak near 1225cm-1 and it is an asymmetric stretch vibration of the "t which is attributed to external linkages between tetrahedral to4 [18]. in spite of the decrease in si/al ratio in gel compositions ii comparing with gel compositions i , the effect of increasing the amount of tpaoh ie tpa/si ratio gave better results concerning nano-sized l 4.3. template solution concentration the concentration by weight of template (organic structure directing agent osda,tpaoh)solution was studied by using three kind of solutions 10%wt , 20%wt and 40%wt , using gel composition i, the samples s3 , s4 , s5 represent 10%wt , 20%wt and 40%wt(tpaoh) respectively. fig. 4. atomic force microscopy reports for samp al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 14 1 and it is an asymmetric stretch vibration of the "t-o" bond to external linkages between tetrahedral to4 [18]. in spite of the decrease in si/al ratio in gel compositions ii comparing with gel compositions i , the effect of increasing the amount of tpaoh ie tpa/si ratio gave sized level. template solution concentration the concentration by weight of template (organic structure directing agentosda,tpaoh)solution was studied by using three kind of solutions 10%wt , 20%wt and 40%wt , using gel composition i, the samples s3 , , s5 represent 10%wt , 20%wt and these samples were prepared at the same temperature 160̊c and same crystallization time 72h .the results show that the best result in surface area and pore volume for s5 (355 m2/g and 0.20721 cm3/g respectively 40%wt(tpaoh) was used with very good crystallinity. 4.4. gel compositions two gel compositions were studied i and ii which they are different in si/al ratio and more template (tpaoh) introduced in the gel compositions ii so tpa/si ratio is more in gel compositions ii . the results reveals ( as shown in the table 2 ) that a decrease in particle diameter down to 50 nm (s15 and s20) are given by compositions ii. atomic force microscopy reports for samples of composition khwarizmi engineering journal, vol. 11, no. 4, p.p. 819(2015) these samples were prepared at the same c and same crystallization time 72h .the results show that the best result in surface area and pore volume for s5 (355 m2/g and /g respectively ) in which 40%wt(tpaoh) was used with very good two gel compositions were studied i and ii which they are different in si/al ratio and more template (tpaoh) introduced in the gel a/si ratio is more in gel compositions ii . the results reveals ( as shown in the table 2 ) that a decrease in particle diameter down to 50 nm (s15 and s20) are given by les of composition ɪ & ɪɪ. najwa saber majeed table 3, average parameter value at different crystallization time and temperatures fig. 5. xrd patterns at different crystallization temperatures (150,160,170 and 180 c) for different crystallization times (48,72,and 96h). average crystallinity% sample code 88.4 s9,s10,s11 (48,72,96h) and 150 0c 91.1 s12,s13,s14 (48,72,96h) and 160 0c 104.4 s15,s16,s17 (48,72,96h) and 170 0c 101.4 s18,s19,s20 (48,72,96h) and 180 0c al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 15 average parameter value at different crystallization time and temperatures. for 48h for 72h for 96h xrd patterns at different crystallization temperatures (150,160,170 and 180 c) for different average bet surface area m2/g average particle diameter ,nm crystallinity% 338.5 82.4 354.7 80.7 341.2 69.3 321.4 67.3 khwarizmi engineering journal, vol. 11, no. 4, p.p. 819(2015) xrd patterns at different crystallization temperatures (150,160,170 and 180 c) for different average pore volume cm3/g average bet surface 0.19115 0.2045 0.20404 0.1929 najwa saber majeed al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 819(2015) 16 group 1 for 72h and different temperature 180,170,160,150 c. group 2 for 96h and different temperature 180,170,160,150 c. fig. 6. scanning electron microstructure images. fig. 7. ftir spectra for the samples prepared at variuos crystallization time (96h,72h,48h) and temperatures of (180,170,160 and150 c). najwa saber majeed al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 819(2015) 17 5. conclusion nanocrystalline zsm-5 was synthesized with considerably matched specifications with theory and previous works. a hydrothermal method was adopted using twin autoclaves carefully designed to meet the requirements( heating, stirring, sealing). the effect of temperature and time of the crystallization also the concentration of template solution on final product specifications like morphology and crystallization were studied. the result showed that the crystallization time, which is the most important parameter, and has a great effect on crystallinity and particle size, crystallization time between 72h-96h gave the best results. crystallization temperature had also a strong effect on crystallinty, purity and morphology of the prepared zsm-5 zeolite .it has noticed that an increase in temperature range between (170 c-180 c),tends to get an increase in crystallinity, which is coincided with previous work[1].template(osda)solution concentration showed that the increase of weight percent of the solution from 10% to 20% to 40% has its strong effect on both increase of crystallinity and decrease of particle size to nano-level size. 11111 acknowledgements the authors express their grateful appreciation to the ministry of oil-petroleum r&d center for conducting bet surface area, the ministry of science and technology for sem, college of science for xrd , afm and ftir. 6. references [1] r. karimi, b.bayati, n.c.aghdam, m.e jtemaee, a.a.babaluo, studies of the effect of synthesis parameters on zsm-5 nanocrystalline material during templatehydrothermal synthesis in the presence of chelating agent, powder technology, vol. 229,pp. 229-236,oct.2012. [2] i.kazuyuki, t. teruoki, k.hiroki, n.yuta, m.takao, preparation of nano-crystalline mfi zeolite via hydrothermal synthesis in water/surfactant/organic solvent using fumed silica as the si source, microporous and mesoporous materials,141 issues13,pp.167-174,may 2011. [3] y.k.krisandi,s.yusri,h.s.gotama,s.octavia ni,r.sihombing,synthesis and characterization of hierarchial co/zsm-5 as catalyst for methane partial oxidation, international journal of environmental and bioenergy,vol.3,no.2,pp.121-131,2012. [4] r.m.mohamed, h.m.aly,m.f.el-shahat, i.a.ibrahim, effect of the silica source on the crystallinity of nanosized zsm5,microporous and mesoporous materials,vol. 79,issues 1-3,pp. 7-12,april 2005. [5] l.shirazi, e.jamshidi, m.r.ghasemi ,the effect of si/al ratio of zsm-5 zeolite on its morphology, acidity and crystal size, cryst.res. technol.vol. 43, no. 12,pp. 13001306, dec.2008. [6] l.t.h.nam,t.q.vinh,n.t.t.loan,v.d.s.th o,x.y.yang,b.l.su ,preparation of bio-fuel by catalytic cracking reaction of vegetable oil sludge, fuel vol.90,issue 3,pp. 10691075,march 2011. [7] r.m.mohamed,o.a.fouad, a.a.ismail, i.a.ibrahim, influence of crystallization times on the synthesis of nanosized zsm5.material letters vol., 59,pp. 34413444,nov.2005. [8] t.tago,h.konno, m.sakamoto, y.nakasaka, t.masuda,selective synthesis for light olefins from acetone over zsm-5 zeolites with nanoand macrocrystal sizes, applied catalyst a: general, vol. 403,pp. 183191,aug.2011 [9] n.viswanadin, s.k.saxena, enhanced performance of nano-crystalline zsm-5 in acetone to gasoline (atg) reaction, fuel,vol. 105,pp. 490-495,march 2013. [10] m.abrishamkar,a.izadi,nano-zsm-5 zeolite: synthesis and application to electrocatalytic oxidation of ethanol, microporous and mesoporous materials,vol. 180,pp 56-60,nov.2013. [11] r.alrubaye ,generation and characterization of catalytic films of zeolite y and zsm-5 on fecralloymetal, phd.thesis, university of manchester,2013. [12] y.wang,s.wang ,hierarchical zeolite: synthesis and application in bioenergy, open journal of advanced materials research ojamr ,vol.1,no.2,pp.1323,aug.2013. [13] m.m.j.treacy, j.b.higgins, collection of simulated xrd powder patterns for zeolite,4th rev.edition/new york,elsevier,2001. najwa saber majeed al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 819(2015) 18 [14] t.armaroli,l.j.simon,m.digne,t.montana ri,m.bevilacqua,v.valtchev,j.pattin,g.bus ca,effect of crystal size and si/al ratio on the surface properties of h-zsm-5 zeolites, applied catalysis a:general,vol. 306,pp.78-84,aug.2006. [15] b.d.cullity, elementsof x-ray diffraction, 2nd edition, addison wesley publishing company, inc.massachusettes, 1965 usa. [16] y.cheng, l.j.wang,j.sh.li,y.ch.yang, x.y.sun,preparation and characterization of nano-sized zsm-5 zeolites in the absence of organic template, materials letters, vol. 59,pp. 3427-3430,nov.2005. [17] m.khatamian, m.irani, preparation and characterization of nanosized zsm-5 zeolite using kaolin and investigation of kaolin content, crystallization time and temprature changes on the size and crystallinity of products,j.iran.chem.soc.,vol.6,no.1,,pp.1 87-194,march 2009 [18] a.i.lupulescu, j.d.rimer,in situ imaging of silicalite-1 surface growth reveals the mechanism of crystallization.science,vol.344,pp.61896193,sep.2014. [19] s.brunaur, p.h.emmet,e.teller, "adsorption of gases in multimolecular layers",j.amer.chem.soc.,vol,60,pp.309319,feb.1938. � ا������ � ��وى ��ر ���د �� )2015( 819 ، ����3، ا���د11�ا���ارز�� ا� 19 � ���) � ��� zsm-5ا��-,��ر !�ع -و و�( ا���")' ��&$�%$# ا��"!�ي) **ا � 0,� ا��,"ر ا����� *!��ى �".� �� � �و�� *���0�/.� -,#اد /*(�� ا %$#"� / )'& ا %$#"� ا � 0�/.: -,#اد/ وا 7�#89�ت �5)'& 34ون ا 1(** :"� ر; dr.najwa_saber@yahoo.com :ا@ �9=و?< ا 5=�#* a.alnaama53@gmail.com : ا@ �9=و?< ا 5=�#** ا����1 $8�.: b?zsm-5ع ا �b)59ر ا c�@b�d ا $�?bيf &f #( ) :5�*=f ( ��;��� 1=��7 ا -– g� دة ا��9�lا k=ار�� و-�"j9#ام ا �/gھ l�95�*=f n�$8f &f ��-: o �5 ا@و� :al2o3:86sio2:5.5tpa:12.7na2o:3.4trien:3320h2o ا 9=* ��?�p �5 ا� al2o3:68sio2:5.4tpa:10na2o:2.6trien:2626h2o : ا 9=* >;���qr ا s9 ا q/اbr =�t�f �"درا– c�@bز� v;�8w o)r اري=k اzsm-5 ي يذb?�$9�ھ< ا 8,= ( ا yk& ا $�/l ھ]ه ا .bا/q در�0 .)ا �\ز/l ا b)59ر و ا b)59روا k=ارة *=9) ��]$��دة ا .^��b ا ��d ا �b)kل (*=f و. l��`g�fا0=ي `< او n��l ( ا $89)r�s/ ( اري=k ن اb)s9 ��$15/ ��)k/ �.$8/و a,^ ارة و ا=k) l�''k9�8�;f v& -ا0=اء وbc ا.و/dودة -j �"b��$��bد ا@4.� ا 'e ة ا ]ر��,ط�b7 ا =%y/ اءو=�k ا ckf �.4@ا �b`– cر�= f=ا?'b5رت و-=و?= ��= –ا�))�f ) l��ص ($�9=و0c#/ص و ا��ت) ا/89/�'��� وye& ا rb$ ا �e�'��س ا �7 . ��bد ا@9? �.4k vks ا i; �دة در�0 ا k=ارة و ز/l ا b)59ر�dدادdf i9$��ن در�0 ا b)59ر (c�@b�d ا ckjاو k"���� وا �y%= ا@ �9=و?< ا $�9�;y/ i%= ا b7ة واوckj .ا '? 5�5< ٥٠ا ]ر�� ا b8kل b9'/ o)rى ?�?bي و-k#ود k ل )1= ا#.� =9/ b?��=اء.?k ا ckf �.4@ا vk` i;�9? o)r لb8k رت ا*#ت اb5'?ا=f =ر�b` ��0b��ت ا �b)1-� وا l/ �5�=7 ا@طbال ا `�k ١"& ١٠٨٠,٨٠٠,٥٥٠ا lr g^` يb?�5�5< ا $k ا &yk ر واb)59 9.(�7 -#ر�0 ا��ن ا 9$�;i ا ` q ذ \�*=9) ��]$��دة ا .^��b ا ��= )bي 9=*�d ا t�f o رت ا� .ا4 6172 al-khwarizmi engineering journal,vol. 1 ant colony optimization based force lower limb mohammed y. hassan *,** department of *email: (received abstract the aim of human lower limb rehabilitation robot is to muscles. this paper proposes the design wearable rehabilitation robot. this robot consists of a hip, knee and ankle joints to enable the patient for motion and turn in both directions. the joints are actuated by pneumatic muscles actuators (pmas). the pmas have very great potential in medical applications because the similarity to biological muscles. takagi-sugeno-kangthreeproportional three-proportional (3-p) controllers for force control. they are designed and simulated to improve the desired joints position specifications such as minimum overshoot, rejection during tracking the desired position medical trajectory. gains of position and force parts of the force required specification. a comparison between the force an enhancement in the results of the second type as compared with the first one keywords: rehabilitation robot, force 1. introduction damage of the central nervous system or spinal cord injuries may result in such a loss of lower limb motor functions. the physical therapy and rehabilitation programs are applied to people with disability to increase their joint range, strength, power, flexibility, and coordination [1]. one type of rehabilitation robots is exoskeleton robot: “exoskeletons are, in general, structures of rigid links, mounted on the body of some living vertebrae and following the main directions and having the main joints of the living organism’s endoskeleton” [2]. in recent years, researches on rehabilitation robot have become an important topic. there are several researches deal with this field such as ollinger. et al. [3] in 2007 that propose for knee joint actuated by electric motor controlled by proportional-integral (pid) controller. also, akdoğan and khwarizmi engineering journal,vol. 12, no. 1, p.p. 6172 (201 ant colony optimization based force-position control for human lower limb rehabilitation robot mohammed y. hassan* shahad s. ghintab of control and systems engineering/ university of technology *email: dr.m.hassan@uotechnology.edu.iq **email: ssswnh5@yahoo.com (received 6 april 2015; accepted 12 september 2015) the aim of human lower limb rehabilitation robot is to regain the ability of motion and to strengthen the weak this paper proposes the design of a force-position control for a four degree of freedom (4 wearable rehabilitation robot. this robot consists of a hip, knee and ankle joints to enable the patient for motion and joints are actuated by pneumatic muscles actuators (pmas). the pmas have very great potential in medical applications because the similarity to biological muscles. force-position control incorporating a proportional-derivative like fuzzy logic (tsk-3-pd) controllers for position control and p) controllers for force control. they are designed and simulated to improve the desired joints as minimum overshoot, minimum oscillation, minimum steady state error ed position medical trajectory. ant colony optimization (aco) is used to tune the gains of position and force parts of the force-position controllers to get the desired position tr a comparison between the force-position controllers tuned manually and tuned by f the second type as compared with the first one with an average of 39%. -position control, lower limb, ant colony optimization. the central nervous system or spinal cord injuries may result in such a loss of lower limb motor functions. the physical therapy and rehabilitation programs are applied to people with disability to increase their joint range, strength, power, flexibility, and coordination [1]. one type of rehabilitation robots is exoskeleton xoskeletons are, in general, structures of rigid links, mounted on the body of some living vertebrae and following the main directions and having the main joints of the living organism’s in recent years, researches on rehabilitation ortant topic. there are researches deal with this field such as ollinger. et al. [3] in 2007 that proposed 1-dof for knee joint actuated by electric motor integral-derivative an and şişman [4] in 2011 presented a robot mechanism with 3 dof, flexion-extension movement for the knee and hip joints, and the abduction movement for the hip joint, for the rehabilitation of lower limbs. the system was designed to imply the patient’s muscle signals using force feedback control method. impedance control method was used for force control, whereas pid position control method was used for position control. furthermore, tu diep and tran 2008 introduced a 1-dof by pma controlled by pid with neural network. akdo˘gan. et al. [6] in 2009 suggested an intelligent controller structure for a knee rehabilitation robot manipulator with 1 controller of the robot manipulator works based on impedance control. also, aminiazar. et al. [7] in 2013 proposed a 2-dof for knee and ankle joints controlled by pd controller. it can be noticed from previous works that they deal with one or two joints of human lower limb al-khwarizmi engineering journal (2016) position control for human shahad s. ghintab** / university of technology regain the ability of motion and to strengthen the weak position control for a four degree of freedom (4-dof) lower limb wearable rehabilitation robot. this robot consists of a hip, knee and ankle joints to enable the patient for motion and joints are actuated by pneumatic muscles actuators (pmas). the pmas have very great position control incorporating a pd) controllers for position control and p) controllers for force control. they are designed and simulated to improve the desired joints imum steady state error, and disturbance ant colony optimization (aco) is used to tune the position controllers to get the desired position trajectory according to the position controllers tuned manually and tuned by aco shows with an average of 39%. position control, lower limb, ant colony optimization. in 2011 presented a robot mechanism with 3extension movement for the knee s, and the abduction-adduction movement for the hip joint, for the rehabilitation of lower limbs. the system was designed to imply the patient’s muscle signals using force-position feedback control method. impedance control method was used for force control, whereas pid position control method was used for position rthermore, tu diep and tran [5] in dof for knee joint actuated by pma controlled by pid with neural network. akdo˘gan. et al. [6] in 2009 suggested an intelligent controller structure for a knee rehabilitation robot manipulator with 1-dof. the controller of the robot manipulator works based also, aminiazar. et al. [7] dof for knee and ankle joints controlled by pd controller. it can be noticed from previous works that they deal with one or two joints of human lower limb mohammed y. hassan al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 6172 (2016) 62 through the design. this causes retraction in workspace and reduces the flexibility when interact with human motion. furthermore, the robots were actuated by electric motors due to their simplicity of modeling control. the drawback of electric actuators that they often are expensive and heavy for high power applications [8]. eelectric motor actuation significantly decreases power consumption during walking in comparison to pneumatic actuation. friction in the robot joint, either in the actuators or in the joints mechanism and the effect of disturbances was not taken into consideration in most of the previous works. in this work, force-position controllers are designed to overcome the nonlinearity inherent in 4-dof lower limb wearable rehabilitation robot [9]. the detailed design and modelling of the 4dof lower limb wearable rehabilitation robot actuated by pneumatic muscles actuators (pmas) has been explained in details in reference [9]. the design of the force-position controllers for the joints of the robot incorporates threeproportional-derivative (tsk-3-pd) like flc for position control and three-proportional (3-p) controllers for force control. these types of controllers are used to deal with the forces that have an effect on the robot links by the patient limb. force-position controllers are designed to improve the desired position specification such as minimum overshoot, minimization of oscillation, minimum steady state error, and disturbance rejection during tracking the desired position medical trajectory. ant colony optimization (aco) is used to tune the gains of position and force parts of the force-position controllers to get the desired position trajectory according to the required specification. 2. force-position controllers the force-position control is the successful execution of an interaction task without jeopardizing itself or the environment. such an interaction requires the control of both, motion and interaction forces. as presented by karam [10], the objective of the force-position control is that the robot’s end-effector responds to forces applied externally, according to some welldefined dynamics. more specifically, the desired dynamic relationship between the end effector position � ∈ �� and the vector of contact forces � ∈ �� are specified as follows [10]: f� − f = k��x� − x� + b��x� � − x� � + m��x� � − x� � … (1) where the parameter �� ∈ ��×� is the stiffness diagonal matrix, �� ∈ ��×� is the damping diagonal matrix and �� ∈ ��×� is the inertia diagonal matrix. �� are the desired joint forces applying to the robot joints in (n). �, �� , �� are the position, velocity and acceleration of the robot system in the cartesian space respectively. the control law of the force that is applied to the dynamic model of robot is [10]: � = ����� �!�"� − "� + �#�"�� − "� � + ����$ + %� − �$�& + ' … (2) where � ∈ �( is the control law applied to robot model, ���� ∈ ��×( is the jacobean matrix and, �! , �# )*+ �$ ∈ ��×� are the position, velocity and force gain matrices respectively. "� = [-+. -+/ -+0]� are the desired trajectory position (in m), �� = [�+. �+/ �+0]� are the joint forces applied to the robot joints (in n), 23 = [24 25 26 27]�are the measured angle from each joint (in degree), � = [�. �/ �0]� are the generated force vector (in n), �$ = [�$. �$/ �$0]� are the joint gains and 8 = [8. 8/ 80]�are the outputs of fuzzy controller. in this work, tuned the gains of forceposition controllers depend on the ant colony optimization (aco) algorithm [11]. however, fig. 1 shows the block diagram for the closed loop dynamic model controlled by force-position controllers. the parameters of force part and position part of the controllers are tuned by aco. mohammed y. hassan al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 6172 (2016) 63 fig. 1. closed loop force-position controlled system tuned by aco. 3. design of force-position rehabilitation robot since the 4-dof rehabilitation robot and pma have high nonlinearity, a force-position controller has the ability to deal with this nonlinearity to achieve good tracking response. the front view and side view of proposed structure (the schematic diagram of the robot mechanism) are shown in fig. 2. a tsk pd-like fuzzy type is designed as a position controller. the inputs of the controller are the (error (e) and rate of error (9�� ), where the control signal is: 8�:� = ;<39�:� + ;=39��:� … (3) the input and output scaling factors are defined as: proportional gain, �kp�, derivative gain �kv�, and output gain �ko�. seven triangular shaped membership functions are selected for each input, fig. 3. the linguistic variables of the membership functions of the flc are; nb (negative big), nm (negative medium), ns (negative small), z (zero), ps (positive small), pm (positive medium), and pb (positive big). the universe of discourse for (e, 9�) is taken within (-1, 1) since the error has positive and negative values while the output universe of discourse is within the range (0, 1) since the valve takes positive values of voltage as input. the values of output membership functions (constant type), of tsk are listed in table 1. a typical rule in a sugeno fuzzy model has the form: if input 1 = x and input 2 = y, then output is z = a.x + b.y + c. … (4) for a zero-order sugeno model, the output level z is a constant (a=b =0). however, the rules of the flc are listed in table 2 and selected by several trials to reach the best position response. the parameters of the force controller incorporating in the forceposition control, equation (1), are selected as; ��=3000 (n/m), ��=200 (n·s/m) and ��=5 (kg). these values are representing a second order reference model with damping ratio and un-damped natural frequency of ζ=0.8164 and wn=24.49 (rad/sec) respectively [12]. the simulink of the force and position controllers is shown in fig. 4 and the simulink of the complete force-position controlled system for lower limb rehabilitation robot is shown in fig. 5. it consists of sub blocks of the dynamic model, pma, the position controller, the force controller and the reference trajectory. table 1, constant membership functions for the output. nb=0.3 nm=0.4 ns=0.527 z=0.647 ps=0.7 pm=0.83 pb=0.99 mohammed y. hassan al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 6172 (2016) 64 (a) front view (b) side view fig. 2. the proposed structure of the lower limb wearable rehabilitation robot. table 2, rules of pd-like position flc. fig. 3. inputs membership functions. b/b∙ nb nm ns z ps pm pb nb nb nb nb nb nm ns z nm nb nb nb nm ns z ps ns nb nb nm ns z ps pm z nb nm ns z ps pm pb ps nm ns z ps pm pb pb pm ns z ps pm pb pb pb pb z ps pm pb pb pb pb mohammed y. hassan al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 6172 (2016) 65 fig. 4. the force and position controllers. mohammed y. hassan al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 6172 (2016) 66 fig. 5. the simulink of force-position controlled system for the lower limb rehabilitation. 4. simulation results in this work, the elliptic trajectory which enable the patient to move in x and y axes is applied. the desired trajectory is given by [13]: ���:� = 0.614 − 0.015 . cos�0.2n . : − n� … (5) o��:� = −0.1 . sin �0.2n . : − 2n� … (6) where 0 ≤ : ≤ 20 seconds. by applying the reference position trajectory, the gains of the pdflc and the proportional gain ��$� of the force controller for each joint are manually tuned using several trials and error and the best values are illustrated in table 3. the response for each axis and the position trajectory are shown in fig. 6 and fig. 7 respectively. in this work, the criterion selected to measure the goodness of results as a performance index is root mean square error (rmse) [14]: ��st = 4 u ∑ w9.5�x� + 9/5�x� + 905�x�u4 … �7� where 9.5�x� is the trajectory error in x-axis, 9/5�x�is the trajectory error in y-axis and 905�x� is the trajectory error in z-axis. n is the number of samples. the performance index for first position trajectory without disturbance is calculated and equals to 0.0547. during rehabilitation exercises, many interior factors, such as position changes and even coughing, usually cause some disturbance to the rehabilitation system. a disturbance of 4*sin (10.π.t) n.m is applied [15]. based on the characteristics of a tremor the value of above disturbance is sufficient to describe the convulsions for human lower leg. the gains of the controller listed in table 3 are used for the elliptic trajectory with disturbance. the response for each axis and the position trajectory are shown in fig. 8 and fig. 9 respectively. the performance index for position reference trajectory with disturbance is calculated and equals to 0.0652. table 3, pd-like force-position flc gains for the first (elliptic) trajectory. gain kp1 kd1 ko1 kp2 kd2 ko2 kp3 kd3 ko3 value 0.23 0.54 3.6 1.5 0.7 6.8 0.04 0.008 0.4 kf1 kf2 kf3 6.4 7.85 5.27 mohammed y. hassan al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 6172 (2016) 67 fig. 6. position response for the x and y axes of the elliptic reference position trajectory without disturbance. fig. 7. position trajectory response without disturbance in the (x-y) axes. fig. 8. position response for the x and y axes of the elliptic reference position trajectory with disturbance. fig. 9. position trajectory response with disturbance in (x-y) axes 0 2 4 6 8 10 12 14 16 18 20 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 time (second) xax is ( m et er ) x-axis response desired actual 0 2 4 6 8 10 12 14 16 18 20 -0.2 -0.15 -0.1 -0.05 0 0.05 0.1 0.15 time (second) yax is ( m et er ) y-axis response desired actual 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 -0.2 -0.15 -0.1 -0.05 0 0.05 0.1 0.15 x-axis (meter) yax is ( m et er ) first trajectory (manual tuning) desired actual 0 2 4 6 8 10 12 14 16 18 20 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 x-axis response time (second) xax is ( m et er ) desired actual 0 2 4 6 8 10 12 14 16 18 20 -0.2 -0.15 -0.1 -0.05 0 0.05 0.1 0.15 time (second) yax is ( m et er ) y-axis response desired actual 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 -0.2 -0.15 -0.1 -0.05 0 0.05 0.1 0.15 x-axis (meter) yax is ( m et er ) first trajectory w ith distubance (manual tuning) desired actual mohammed y. hassan al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 6172 (2016) 68 it is difficult to enhance position tracking performance using the controller tuned manually. the process of tuning the gains of the controllers consumes time and efforts. in this research, aco algorithm is used to tune the gains of the controllers in order to reach the best position performance. to get more accurate position responses, the values of the gains �kp, kv, ko and kf� for each controller are tuned by aco to achieve the desired specifications. the number of iterations for position trajectory is 40 iterations. the algorithm stops iterating either when an ant found a solution or when a maximum number of iterations have been performed. table 4 lists the parameters of force-position controllers obtained by aco tuning to follow the reference position trajectory without disturbance. the performance index for the elliptic trajectory without disturbance is calculated and equals to 0.036. however, the response of each axis and the position tracking responses in the x, y cartesian space are shown in figs. 10 and 11 respectively. moreover, fig. 12 shows the performance index obtained by aco. here the disturbance of 4*sin (10.π.t) is applied. the same parameters listed in table 4 are used for trajectory with disturbance. the performance index for position trajectory with disturbance is calculated and equals to 0.0362. however, the position tracking responses in the x, y cartesian space are shown in figs. 13 and 14 respectively. table 4, pd-like force-position flc gains for the elliptic trajectory tuned aco. gain kp1 kd1 ko1 kp2 kd2 ko2 kp3 kd3 ko3 value 0.0081 0.0029 4.6456 0.0496 0.0067 4.557 0.001 0.001 0.0065 kf1 kf2 kf3 2.381 4.6962 0.0055 fig. 10. position response for the x and y axes of the elliptic reference position trajectory tuned by aco without disturbance. 0 2 4 6 8 10 12 14 16 18 20 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 time (second) xax is ( m et er ) x-axis response desired actual 0 2 4 6 8 10 12 14 16 18 20 -0.1 -0.05 0 0.05 0.1 time (second) yax is ( m et er ) y-axis response desired actual mohammed y. hassan al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 6172 (2016) 69 fig. 11. position trajectory response without disturbance. fig. 12. aco performance index response. fig. 13. position response for the x and y axes of the elliptic reference position trajectory with disturbance. 0.55 0.6 0.65 0.7 0.75 0.8 0.85 0.9 0.95 1 1.05 -0.1 -0.05 0 0.05 0.1 x-axis (meter) yax is ( m et er ) first trajectory w ithout disturbance (aco tuning) desired actual 0 5 10 15 20 25 30 35 40 0.034 0.036 0.038 0.04 0.042 0.044 0.046 0.048 fitness response for the first trajectory (elliptic) iteration fit ne ss 0 2 4 6 8 10 12 14 16 18 20 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 x-axis response time (second) xax is (m et er ) desire actual 0 2 4 6 8 10 12 14 16 18 20 -0.1 -0.05 0 0.05 0.1 time (second) yax is ( m et er ) y-axis response desired actual mohammed y. hassan al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 6172 (2016) 70 fig. 14. position trajectory response with disturbance. 5. conclusions force-position controllers were designed to control the proposed robot. result showed that: 1. the proposed controller using manual tuning could not overcome the nonlinearity of dynamic model, nonlinearity of pma, effects of frictions, and disturbances. 2. aco algorithm was used to tune the gains of the force part and position part of forceposition controllers to satisfy the desired specification. results of applying the medical trajectory show an average enhancement in the position trajectory. 3. (without disturbance and with disturbance) for elliptic trajectory (39 %). 4. for the proposed force-position controllers tuned by aco, the results of the elliptic trajectory were compared with the results of reference 11. the percentage of enhancement for x and y axes are 50 % and 85 % respectively. 5. the proposed force-position controllers tuned by aco had achieved the desired performance and compensated the nonlinearity of frictions, external disturbance and any other nonlinearity in the proposed model. list of symbols symbols definition unit. �� damping diagonal matrix ^. _/` f generated force ^ �� the desired joint forces applying to the robot joints n �� stiffness diagonal matrix ^/` �� inertia diagonal matrix ;a � the position �� the velocity �<3 proportional gains of ith controller �=3 velocity gains of ith controller �b3 output gains of ith controller �$3 the force gain of ith controller j jacobean matrix u voltage input volt 23 joint angle of link i +9ac99 d damping ratio e( un-damped natural frequency c)+/_ 9.�x� the trajectory error in x axis ` 9/�x� the trajectory error in y axis ` 90�x� the trajectory error in z axis ` 0.55 0.6 0.65 0.7 0.75 0.8 0.85 0.9 0.95 1 1.05 -0.1 -0.05 0 0.05 0.1 x-axis (meter) yax is ( m et er ) first trajectory w ith disturbance (aco) tuning desired actual mohammed y. hassan al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 6172 (2016) 71 6. references [1] nef, t.; mihelj, m.; riener, r.: armin: a robot for patient-cooperative arm therapy. medical and biological engineering and computing, international federation for medical and biological engineering, 45, 887900, 1 july (2007). [2] rocon, e.; pons, j. l.: exoskeletons in rehabilitation robotics, springer-verlag berlin heidelberg, 1–20, (2011). [3] ollinger, g. a.; colgate, j. e.; peshkin, m. a.; goswami, a.: active-impedance control of a lower-limb assistive exoskeleton. ieee 10th international conference on rehabilitation robotics, june 12-15, noordwijk, netherlands, 188-195, 12-15 june (2007). [4] akdoğan, e.; şişman, z.: a muscular activation controlled rehabilitation robot system”, springer-verlag berlin heidelberg, 271–279, 2011. [5] thanh, t. d. c.; phuc, t. t.: neural network control of pneumatic artificial muscle manipulator for knee rehabilitation. science & technology development, 11, 03, 16-29, (2008). [6] akdo˘gan, e.; taçgın, e.; adli, m. a.: knee rehabilitation using an intelligent robotic system. springer science+business media, 20, 195-202, jan. (2009). [7] aminiazar, w.; najafi, f.; nekoui, m. a.: optimized intelligent control of a 2degree of freedom robot for rehabilitation of lower limbs using neural network and genetic algorithm. journal of neuro engineering and rehabilitation, (2013). [8] hassan, m. y.: a neural network based fuzzy controller for pneumatic circuit, eng. &tech. journal, 28, 2010. [9] hassan, m. y.; ghintab, sh. s.: modelling and position control of human lower limb rehabilitation robot using pneumatic muscle actuators. accepted to be published in al-mansour journal, iraq 11/9/ (2014). [10] hassan, m. y.; karam, z. a.: modelling and force-position controller design of rehabilitation robot for human arm movements, eng. &tech. journal, 32, 8, 2079-2095, (2014). [11] chiha, i.; liouane, n.; borne, p.: tuning pid controller using multi objective ant colony optimization. hindawi publishing corporation applied computational intelligence and soft computing journal, 1-7, (2012). [12] wang, j.; li , y.: hybrid impedance control of a 3-dof robotic arm used for rehabilitation treatment. 6th annual ieee conference on automation science and engineering toronto, ontario, canada, 768773, aug. (2010). [13] chang m. k.; liou, j. j.: t-s fuzzy controller applied to lower limb rehabilitation robot actuated by pneumatic muscle actuators. cacs international automatic control conference, national taipei university of technology, taipei, taiwan, november 27-29, (2009). [14] karam, z. a.: design and implementation of rehabilitation robot arm, m.sc. thesis, university of technology, control and system eng. dept., dec. (2013). [15] pan, l.; song, a.; xu, g.; li, h.; xu, b.: safety supervisory strategy for an upperlimb rehabilitation robot based on impedance control. international journal of advanced robotic systems, 10, 127, 1-12, (2013). ��� ���� ��� � ��� 1، ا�� د12 � � ا���ارز�� ا��� ��� ا�� ،-61 72 )2016( 72 �� '&�#� ام $�ارز��� ��#� ة ا�� " -���! ��ة����2 � و'�,-ت أ.-دة ,&ھ�" ا*ط اف ا�� ��� ���� ��* �**�7#-ب��34 5 *،** �'(ا!2345( ا!01 /!/. / -)� ھ +*( ا!)'&%ة و ا! � dr.m.hassan@uotechnology.edu.iq : ا:!10%و89 ا!6%7+ * ssswnh5@yahoo.com : ا��� رو�� ا��ر�د ** �� ا��8 � . ا!u+ف t3 روo/?4ت أ4dدة ا!s1ھ'r ا!p4q( m.n4oاء ا!)j! )'ckط%اف ا!7@%6( ھ/ أ4dدة ا!<+رة bcd ا!a@8 و?</6( ا!2=>ت'av? wx7!و6<+م ا ورا2o( [rvk3 8 ا!rc40، !%وo/ت 03/ن t3 أرo] در.4ت t3 ا!x%6(، إ_ 41ن rvk3 8] 4u 3 ا!/رك، و_4!^( [rvk3 8 ا!%\7() 3/-] -/ةt3 %&'(3) 9/ع 4a21*4oل j@3>ت ا!c=2( إذ 16� ?h6%x ا!rp4ka . وھgه ا!+ر.4ت t3 ا!x%6(، \4['(؛ :4dدة ?sھ'r ا!ac! d6%a@8 وا!+وران ا!81u. b ا!'t'a وا!')4ر � .ا!7@%6(ا!u/اn'(، و26+ ھgا ا! /ع t3 ا!j@a>ت، اr=]n [8 ا!1&7'<4ت ا!&7'(؛ 9�%اً !q/اlp ا!2c! )uo4@a=>ت o%!ا bcd 8] )'!42!ا )'&p<!ا t3 �، إ: ان ا!)'&%ة bcd ?71] ا!a)4رات ا!&7'( -+ ?td ra طq6% 3)'&%ات 'av1!9/ع ) -/ة ـ 3/-](ا t3 [-/ac! 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[-/a ا!p wx7/ارزa21(3 )'3%ات ا! ra اa1d+ .ات، [=>ً td 3<4و3( ا:ض&%ا4oتو?<r'c ا!gog1ب، و?<r'c 9)7( ا!s&q [8 3/ا-] ا!a)4ر � q1*so+ام p/ارزa21(3 )'3%ات ا! ra ان ھ 4ك ?t(x [8 أ_r17. و.mء ا!</ة؛ !j%ض ?t'(x ا!a/ا4kpتj a!6+و46 وا �j a!ا %&'(a!ا zn419 t'o )94ر>a!ا %.٣٩\2a+ل 2o ( )7( o+م ?)c'} ا:ض&%ا4oت ا!4qر.'( و3] ?)4u&'c(3/-] ا!a)4ر ا!&87 <4d6963726f736f667420576f7264202d20dac8cfc7e1dfd1ede320dec7d3e32032332d203334> al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 15, no. 1, march, (2019) p.p. 2334 design of pv solar energy generator using mppt technique to control single input/multiple outputs (dc-dc) converter abdul kareem kasim abdul raheem department of electromechanical engineering/ university of technology/ baghdad/ iraq email: kareemss78@yahoo.com (received 8 january 2018; accepted 4 june 2018) https://doi.org/10.22153/kej.2019.06.002 abstract the paper presents the design of a system consisting of a solar panel with single input/multiple outputs (dc-dc) buck converter by using simulink dialogue box tools in matlab software package for simulation the system. maximum power point tracking (mppt) technique depending on perturb and observe (p&o) algorithm is used to control the output power of the converter and increase the efficiency of the system. the characteristics of the msx-60 pv module is chosen in design of the system, whereas the electrical characteristics (p-v, i-v and p-i curves) for the module are achieved, that is affected by the solar radiation and temperature variations. the proposed design module has been found to be stable for any change in atmospheric temperature and solar radiation. the maximum power is achieved at voltage 17v and current 3.5a when using mppt controller, and approximate results for multiple outputs voltages and current (9v:2a, 5v:1a, 2.2v:0.5a) are obtained. the proposed model is very useful for engineers, researchers and experts to design their systems which require a simple and accurate pv cells model. keywords: buck dc-dc converter, mathematical modeling, matlab/ simulik, mppt, pv cell/panel. 1. introduction the photovoltaic energy is one of the renewable sources in the past decade. it is a clean energy and a high reliability. so, it can be considered as one of the most sustainable renewable energy. solar energy is one of the most important renewable sources of energy. the most important factors affected on the performance of solar cell are temperature, solar irradiation and pv technology type [1]. b. v. chikate and y. a. sadawarte [1] studied the effects of ambient conditions and pv technology type on the efficiency of solar module. the performance of solar cell is depending on converting incident solar radiation into electricity which pointing to conversion efficiency. the design is used to obtain the current–voltage (i–v) characteristics with defined the maximum power point(mpp) [2]. the pv and i-v characteristic of the cell are nonlinear due to complex relationship between current and voltage , and vary with change in cell temperature or solar radiation. there is single point on p-v or i-v characteristics curve where pv module produces highest output power at mpp [1]. m. a. ozcelik and a. s. yilmaz [3] presented the design of pv generator by using matlab/simulink software, and studying the effect of mppt in pv system. s. rout [4] presented the implementation of a pv model using matlab/simulink software. the mathematical equations of photo current and voltage are used for design a pv system. matlab dialogue box from simulink block libraries is used for simulation. p. srivastava [5] examined the factors which affect the efficiency of solar cells. these factors are energy conversion, cell temperature, maximum power point tracking for solar cell. dominique bonkoungou et al [6] presented an improved numerical approach modeling for i-v abdul kareem kasim al-khwarizmi engineering journal, vol. 15, no. 1, p.p. 2334 (2019) 24 characteristics of pv modules. the thermal performance of the proposed approach is improved by a coefficient computed by using the maximum power temperature coefficient provided by manufacturers. r. r. patel and t. a. trivedi [7] presented a mathematical equation for design the module and simulation of pv cell panel by using matlab/simulink software. they show the variation in pv cell behavior under different environmental conditions. in many applications, the pv cell panel must be connected to power converter system are used. matlab/simulink helps for studying the operation the converters by selecting the matrix manipulations in it, plotting of functions, implementation of mppt algorithms and acts as user interfaces with the solar pv modules for monitoring the performance of the system [8]. among the researches that deals with the design of these converters as follows: kavitha h.s. [9] proposed converter uses one power switch which is high efficiency power conversion, multiple outputs. to reduce the switching and conduction losses, the techniques of soft switching and voltage clamping are used. mahesh g. n. m. et al [10] provided the operation and mathematical model of a buck dcdc converter for simulation using simulink dialogue blocks. they discussed the transfer function of the system in order to use the matlab tuning tools to obtain better settling time, rise time and peak overshoot. s. p. singh et al [11] presented a soft switching technique for studying high efficiency buck dcdc converter. they will focus on design, analysis and simulation buck converter modeling. the converter is designed in continuous conduction mode. in this paper, a modeling of solar pv emulator utilizing single input/multiple output (simo) buck dc-dc converter is design and carried in matlab software by using dialogue box from simulink block libraries for simulation. maximum power point tracking (mppt) technique depending on perturb and observe (p&o) algorithm is used to regulate the output power of the converter. the characteristic of a pv cell has been tested when taking the effect of changing the temperature and solar radiation. the simulink design of dc-dc buck converter circuit and mppt controller is presented. the mppt controller is used for increasing the efficiency of the system. 2. pv cell mathematical modeling a photovoltaic (pv) module is formed by connecting many solar cells in parallel and series. a single diode model of solar cell is shown in fig.1. the equivalent electric circuit consists of a photocurrent source(���), a diode (�), a parallel resistor (���) and a series resistor (��) [12]. fig. 1. solar cell model. the electrical characteristics of the pv cell module can be describing by the following sets of equations [12]: � = ��� − � − ��� …(1) here: � : diode current (a); ���: current through the shunt resistance (a) ��� = ���� + ���� − ���� � ���� …(2) here: ���:short circuit current; ��: temperature coefficient of short-circuit current (a/k) at 25 °c and 1000�/��; �: cell operating temperature (k); ��: cell‘s reference temperature (298k); �: solar irradiance (�/��); ��: reference solar radiation (1000�/��). � = � !"#$ % &'()*+ , − 1 …(3) here: � : diode saturation current(a); . : diode voltage (v); /: boltzmann‘s constant (1.38#103�45/�); 6 : diode ideality factor; 7: electron charge (1.602#103:;<� � = � ,> � ??��4 "#$ @abc>d � :?� − :?�e …(4) here: fg: the band-gap energy of the semiconductor (fg= 1.12 ev for the polycrystalline silicon at 25°c); � ,>: the nominal saturation current. .�� = . . = . + ��� … (5) ��� = &hijhi = &kljmjhi …(6) the thermal voltage (.?) of the cell can be set by the equation: .? = n?a …(7) then equation [1] become : abdul kareem kasim al-khwarizmi engineering journal, vol. 15, no. 1, p.p. 2334 (2019) 25 � = ��� − � @"#$ o&kljh>&* p − 1e − @&kljhjhi e … (8) the equation (8) describes p-v and i-v characteristics of the solar cell. the characteristics vary with cell temperature and solar irradiation as shown in fig.2 [13]. maximum power �qr� point is the operating point s�.r�r� at which the power dissipated in the resistive load is maximum [14]: qr = .r�r … (9) fig. 2. characteristics of solar cell the performance of solar cell is tested under the standard test condition (stc), where an average solar spectrum at air-mass (am 1.5) is used, the cell temperature is defined as 25 ºc, and the global irradiance is 1000�/�� [2]. 3. pv array mathematical module the output power produced from single solar cell is not enough for any application. therefore, to generate enough power, the pv modules are connected in parallel or series to form pv arrays which are used to increase the efficiency. the equivalent circuit for the solar module is shown in fig.3 [10], where t� the number of cells connected in series and t� the number of cells connected in parallel. fig. 3. general pv equivalent circuit model. based on the equivalent circuit of a pv module, its characteristic equation is given as follows [12]: ���,u�>vw = t���� … (10) � ,u�>vw = t�� … (11) 6,u�>vw = t�6 … (12) ��,u�>vw = xmxy �� … (13) � = t���� − t�� z"#$ [\&kl ]h]yjh^ xh�()*+ � _ − 1` …(14) � = t���� − t�� a"#$ b\ .t� + ���t� ^ �6/�7 � c − 1d − ]y]h &kljhjhi … (15) the electrical characteristic of the system is describing by equation (15) which is a non-linear mathematical equation and define the relationship between current and voltage generated by a pv module [12]. 4. simulink of pv cell array module matlab/simulink software package was used to implement the model of the solar pv emulator. the msx-60 pv module is chosen as a reference for this simulink, that provides 60w nominal maximum power. parameter specification of the msx-60 module is shown in table (1) [7]. the pv cell characteristics affected by these parameters. table 1, parameter specification of msx-60 module(e =fgh/ij , k = jlm� values parameters 60w qr 17.1v .r 3.5a �r 3.8a ��� 21.1v . � 3ma/c /� 40c noct 1.35 n 0.180ω �� 360ω ��� 1 t� 36 t� 0.000021a � ,> mathematical equations from equations (1) to (8) are used to carry out the pv model as shown in fig.4 with input parameters temperature and abdul kareem kasim al-khwarizmi engineering journal, vol. 15, no. 1, p.p. 2334 (2019) 26 irradiance. the contents of the block pv-module in fig. 4 are shown in fig. 5. mathematical equation (15) is used to implement the behavior of the pv model by using matlab/simulink program. fig. 4. simulink of solar pv model. fig. 5. block pv-module simulink 5. maximum power point tracking the maximum power point (mpp) is an particular operating point where the power supplied to the load is at maximum and noted by ( qr ) as shown in fig.2. to increase the efficiency of pv module, it is important to operate pv energy generate system close to mpp. the output power is always variations according to atmospheric temperature and solar radiation, then, the mppt controller with dc-dc converter is used for transferring maximum power from the solar pv module to the load [5]. the maximum output power can be calculated as [15]: qr = .r�r … (16) the perturb and observe (p&o) algorithm is used for achieve the maximum output power. the most basic form of the algorithm (fig.6) operates as follows[16]: the output power is achieved by multiplying .�n and ��n signals, then the change of power determined the direction of the mpp. assume the operating point of pv module is away from the mpp, the operating voltage of pv module is perturbed by a small increment, and the resulting change of power ∆q is observed. if the ∆q is positive, then the operating point is moved closer to the mpp. thus, the operating point moved in the same direction, and the further voltage perturbations should move toward the mpp. if the ∆q is negative, the operating point has moved away from the mpp, and the voltage perturbation should be reversed to move back toward the mpp. in fig. 6, (/) indicates to current values and �/ − 1� indicates to previous values for current, voltages and power. v_i top 25 repeating sequence product p_v top g vpv1 vpv ipv p g 1000 workspace_ipv ipv workspace _vpv vpv workspace _ppv ppv vpv 2 ipv 1 temp in kelvin top tc tref subsystem iph1 tc vpv is ipv isc 3.8 is1 tc tref iscr is irs tc iscr irs iph g tc isc tref iph display2 273 display1 3.239e-010 display 1.85e-008 vpv1 3 g 2 top 1 abdul kareem kasim al-khwarizmi engineering journal, vol. 15, no. 1, p.p. 2334 (2019) 27 fig. 6 flow chart of (p&o) algorithm used in our mppt charge controller 6. mppt simulink the matlab/simulink design for (p&o) algorithm is implemented as shown in fig.7. fig. 7. mppt simulink. 7. design of dc-dc buck converter switch mode dc-dc converters are used to describe a circuit which convert unregulated dc input voltage to provide single or multiple output dc voltages by a switching action. fig.8 shows the dc-dc buck converter circuit of step down dc voltage [8]. sometimes, an active power switch is used instead of freewheeling diode to operate at low output voltage and high efficiency, this converter is called as synchronous dc-dc buck converter [17]. the buck converter circuit is operating in continuous current mode (ccm), and the mosfet transistor acts as switch and turned (on) and (off) depending on the signal applied to its gate from pulse width modulation circuit d 1 vn-vb vn vb v filter switch2 switch1 scope1 saturation repeating sequence1 pn-pb pn pb in if deltap*deltav>0 -1 if deltap*deltav<0 1 ib i filter deltap*deltav deltad -cdb d state d sampleconstant2 0 constant1 1 add i 2 v 1 abdul kareem kasim al-khwarizmi engineering journal, vol. 15, no. 1, p.p. 2334 (2019) 28 which is used to control the power transmitted from input to the load [8]. fig. 8. buck converter circuit the differential equation at on condition is given by[18]: .� = p< q&r sq + tj &u s + .��v� … (17) if .�(t) is constant, so equation (17) can be written as: .� − . = p lw�s� s … (18) the inductor and capacitor currents waveforms are shown in fig. 9[18]. fig. 9. a. inductor current waveform, (b) capacitor current waveform. in a steady state condition, when v → �yx =z� , the inductor current �t is: �t = &{3&|t z� + �t} … (19) here �t| is the initial value of the inductor current and z is the duty cycle. the current ripple ∆�t is given by: ∆�t = �t − �t} = &{3&~t z� … (20) in off condition, the first differential equation is: p lw�s� s = − .y … (21) the solution of equation (21) yields: �t�v� = 3&|��t v + �t … (22) for v → �y�� = �1 − z��, the �t decreases to �t} which is minimum value as: �t} = 3&~t �1 − z�v + �t … (23) then the current ripple can be expressed as: ∆�t = &|(t �1 − z�� …(24) by comparison between equations (20) and (24), it is obvious that: . = z.� … (25) from fig. 9, the average current flow through the capacitor is zero, but the capacitor will charged in one-half cycle, and the equation described the increasing in charge is : ∆� = :� ∆lw� ?� = :� ∆�t� … (26) and because .� = . , then: ∆. = ∆�� … (27) then from (24) and (26): ∆. = :�t�uq&~ … (28) from fig.8, the value of the inductor l is: p = �.� − . � � uh��l� …(29) from equation (28): < = :�tuq∆&~ . …(30) 8. single input/ multiple outputs dc-dc buck converter for single input/ multiple outputs (simo) circuit, one inductor and three power switches are used and must be properly driven. for dc-dc buck converter with three outputs, the three standard dc-dc buck converters are used to control independently the three output voltages. fig.10 shows a electrical circuit with single input and three outputs [17]. abdul kareem kasim al-khwarizmi engineering journal, vol. 15, no. 1, p.p. 2334 (2019) 29 fig. 10. single input/multiple outputs circuit diagram. 9. simulink of multiple output buck dcdc converter the simulink of the simo dc-dc buck converter in continuous conduction mode are carried by using the values of capacitance(c) = 1000μf, inductance(l) = 0.11h, resistance(�)= 5ω. fg.11 shows the simulink model for buck converter. fig. 11. buck converter simulink (multiple outputs). 10. system design fig.12 shows the block diagram of the proposed system design. the inputs of the mppt controller are ��n and .�n from the pv panel. the output (�) of the controller is fed to buck dc-dc converter which produce three output voltages for using in different applications. fig. 12. proposed system design. 11. simulink modeling of the proposed system fig.13 shows the simulink circuit of the proposed system design employing solar cell panel and dc-dc buck converter controlling by mppt controller. the system is used to produce three outputs voltages and currents. the approximate results of the system module are (9v:2a, 5v:1a, 2.2v:0.5a). s0vs s3 g m d s s2 g m d s s1 g m d s powergui continuous voltage measurement2 v + voltage measurement1 v + voltage measurement v + subsystem1 out1 out2 out3 out4 scope4 scope3 scope2 rl3rl2 rl1 l2 l1 l il current measurement3 i+ il current measurement2 i+ il current measurement1 i+ c3c2 c1 g m d s abdul kareem kasim al-khwarizmi engineering journal, vol. 15, no. 1, p.p. 2334 (2019) 30 fig. 13. model of solar pv emulator utilizing buck converter. 12. results and discussion the proposed pv module was simulink by using dialogue box from block libraries in matlab. the results are as follows: 1. fig.14 shows the i–v, p–v and p-i characteristics for different values of solar irradiation (400, 700 and 1000 �/��) at constant temperature (25 °c). when the irradiation increases, the power and current increases as shown in fig. 14(a,b) respectively. the variation of voltage is very small in both conditions. the relationship between the power and current is shown in fig.14c. the value of the power is approximately 60w which is the maximum power of system operation, and the maximum value of the current is 3.8a. these operating condition leads to increase the output power. 2. fig.15 shows the i–v, p–v and p-i characteristics for different values of temperature (25, 35 and 45 °c) at constant irradiation (1000�/��� here, when the operating temperature increases, the power and output voltage decreases as shown in fig.15(a,b). the value of power is 60w at temperature 25 °c, and decreases when the temperature increases. the variation of current is very small as shown in fig.15c. this operating condition leads to reduce the output power. 3. from the pv characteristics we can observe that, there is a point at which the power output is maximum which gives the maximum efficiency. in the standard test conditions, it was found that the proposed pv emulator produces the maximum power at 60w with voltage 17v and current 3.8a with increasing irradiation at constant temperature. for comparison, according the datasheet, at standard test conditions, the msx-60 solar module produces the maximum power 60w with voltage at the maximum power of 17.1v and current of 3.5a. (a) (b) s0 s2 g m d s s1 g m d s powergui discrete, ts = 5e-005 voltage measurement2 v + voltage measurement1 v + voltage measurement v + vo3 v + top1 1000 top 25 scope4 scope 3 scope 2 scope1 rl3rl2 rl1 p_v1 top g vpv1 vpv ipv1 mppt v i d l2 l1 l ipv s + il current measurement3 i+ il current measurement2 i+ il current measurement1 i+ c4 c3c2 c1 s3 g m d s g m d s 0 5 10 15 20 25 0 20 40 60 80 100 volltage (v) p o w e r (w ) 1k w/m2 700 w/m2 400 w/m2 0 5 10 15 20 25 0 1 2 3 4 5 6 voltage (v) c u rr e n t) (a ) 1k w/m2 700w/m2 400w/m2 abdul kareem kasim al-khwarizmi engineering journal, vol. 15, no. 1, p.p. 2334 (2019) 31 (c) fig. 14. (a) p-v, (b) i-v and (c) p-i characteristics at t=25c (a) (b) (c) fig. 15. (a) p-v, (b) i-v and (c) p-i characteristics at s=1000w/m2. 4. fig.16 (a,b) shows the continuous level of the .�n and ��n values respectively, that is fed to mppt controller to produce switching signal of the required duty cycle as shown in fig. 16c to control the dc-dc buck converter for achieve maximum efficiency according on the (p & o) algorithm. the output of mppt is signal for two operating conditions, the duty interval (� >) and the freewheeling mode (� uu). however, these mppt pulses more convenient for regulating the output voltages of the buck dc-dc converter. (a) (b) (c) fig.16. ��� , ��� and mppt switching waveforms. 5. for this proposed design, the module formed by connecting 36 pv cells in series. the output voltage can be calculated by multiplying the cell voltage by the number of the cells, while the total current is equal to the cell current. fig.17 shows the simulated waveforms of three output voltages and currents, here approximate values of the first output voltage of circuit is 0 1 2 3 4 5 6 0 20 40 60 80 100 current(a) p o w e r( w ) 1kw/m2 700w/m2 400w/m2 0 5 10 15 20 25 0 20 40 60 80 100 voltage (v) p o w e r( w ) 45 c 35 c 25 c 0 0.5 1 1.5 2 2.5 3 3.5 4 0 10 20 30 40 50 60 70 80 90 100 current(a) p o w e r( w ) 25 c 35 c 45 c abdul kareem kasim al-khwarizmi engineering journal, vol. 15, no. 1, p.p. 2334 (2019) 32 9v and current is 2a, the second output voltage is about 5v and current is about 1a, and the third output voltage is about 2.2v and current is about 0.5a. fig. 17. simulink results for output voltages and currents. 13. conclusion a matlab/simulink model for the pv solar panel with multiple outputs dc-dc converter controlling by mppt technique was developed and presented in this paper. the pv system module is design depending on the circuit equations of solar cell model. the electrical characteristics (p-v, i-v and p-i curves) are achieved for msx-60 solar module that explains its dependence on the solar radiation and atmospheric temperature. when temperature remains constant at 25°c, and the radiation increases, the current and voltage of the cell model increase, this leads to an increase in the output power. and when the radiation level keeps constant at 1000�/�� and the cell temperature increases, the current increases, but the voltage decreases, this leads to reduce in output power. the maximum power is achieved at voltage 17v and current 3.5a with mppt technique. the perturb and observe algorithm is used for achieve maximum power point. the regulator outputs of buck converter controlling by the signal feds from mppt controller are successively achieved. approximate results for multiple output voltages and current (9v:2a, 5v:1a, 2.2v:0.5a) are obtained. 14. references [1] bhalchandra v. chikate and y.a. sadawarte, " the factors affecting the performance of solar cell", international journal of computer applications, international conference on quality up-gradation in engineering, science and technology, pp.1-5, 2015. [2] parimita mohanty, tariq muneer, eulalia jadraque gago and yash kotak, solar photovoltaic system applications, springerinternational publishing switzerland, 2016. [3] mehmet ali özçelik and ahmet serdar yilmaz," effect of maximum power point tracking in photovoltaic systems and its improving and its application of wireless energy transmission", journal of clean energy technologies, pp. 411-416, vol. 3, no. 6, november 2015 [4] smitanjali rout, "mathematical modelling of grid connected photovoltaic system using matlab/simulink and hardware implementation", international journal of computer applications, international conference on emergent trends in computing and communication, pp.6-11, 2015. [5] priyank srivastava, pankaj gupta, amarjeet singh, "critical factors affecting efficiency of maximum power point tracking in solar cells", journal of physical sciences, engineering and technology, vol.7, no.1, pp.1-8, 2015. [6] dominique bonkoungou, zacharie koalaga, donatien njomo, françois zougmore, "an improved numerical approach for photovoltaic module parameters acquisition based on single-diode model", international journal of current engineering and technology, vol.5, no.6, pp.3735-3742, 2015. [7] ravikumar r patel, tapan a trivedi, "mathematical modelling and simulation of pv penal", international journal of electronic and electrical engineering.vol.7, no.7 pp.735-742, 2014. [8] s. sumathi, l. ashok kumar and p. surekha, solar pv and wind energy conversion abdul kareem kasim al-khwarizmi engineering journal, vol. 15, no. 1, p.p. 2334 (2019) 33 systems, springer-international publishing switzerland, 2015. [9] kavitha h. s.,"high efficiency single input multiple output dc-dc converter", international journal of informative & futuristic research, vol.3, no.5, pp.16591668, 2016. [10] mahesh gowda n m, yadu kiran, s.s parthasarthy, "modelling of buck dc-dc converter using simulink", international journal of innovative research in science, engineering and technology", vol.3, no.7, pp.14965-14975, 2014. [11] sugandhra pal singh, deepak kumar singh, harish kumar, rheesabh dwivedi, "designing and parametric variation of pi controller for buck converter for constant voltage applications", international journal of engineering trends and technology, vol.13 no.4, pp.169-174, 2014. [12] mboumboue edouard, donatien njomo , " mathematical modeling and digital simulation of pv solar panel using matlab software", international journal of emerging technology and advanced engineering, vol.3, no.9, pp.24-32, 2013. [13] subarto kumar ghosh, mohammad hasanuzzaman shawon, ashifur rahman, rifat abdullah, "modeling of pv array and analysis of different parameters", international journal of advancement in research & technology, volume 2, no.5, pp.358-363, 2013. [14] ashish kumar singhal, jitendra singh kirar, "matlab based modelling of pv array at different irrediation level using mppt technique", international journal of electronics communication and computer engineering vol. 4, no.1, pp.44-47, 2013. [15] abbas hamid sulaymon, emad talib hahsim and shaymaa alaulddin mahdi, "efficiency prediction and performance characterization of photovoltaic solar panel at baghdad climate conditions", alkhwarizmi engineering journal, vol.9, no.2, pp.5768, 2013. [16] muhammad riazul hamid, jakaria rahimi, sabrina chowdhury, t.m. moniruzzaman sunny, "design and development of a maximum power point tracking (mppt) charge controller for photo-voltaic (pv) power generation system", american journal of engineering research (ajer), vol.5, no.5, pp-15-22, 2016. [17] g. lingeswaran , r.rajasekaran, "single input three output dc-dc buck converter", international journal of technology and engineering system, vol.5, no.1, pp.45-50, 2013. [18] s. mouhadjer, a. chermitti and a. neçaibia," comprehensive and field study to design a buck converter for photovoltaic systems",revue des energies renouvelables vol. 1, no. 2, pp.321-330, 2012. )2019( 23-34، صفحة 1د، العد15دجلة الخوارزمي الهندسية المجلم عبد الكريم قاسم 34 للسيطرة على محول mpptتصميم مولد طاقة شمسية يستخدم تقنية مدخل مفرد/ مخرج متعدد يتيارمستمر) ذ -(تيارمستمر قاسم عبدالرحيمعبدالكريم الجامعة التكنولوجية /قسم الهندسة الكهروميكانيكية kareemss78@yahoo.com :البريد االلكتروني الخالصة buckمدخل واحد / متعدد المخارج نوع يتيار مستمر) ذ -منظومة مكونة من لوح ضوئي شمسي مع محول (تيار مستمر لتصميمالى يتطرق البحث التي (mppt)استخدام تقنية تتبع نقطة اعلى قدرة لمحاكاة المنظومة. تم matlabفي الحقيبة البرمجية )simulinkادوات صندوق حوار ( باستخدام في تصميم msx-60 النموذج الضوئي خصائص وزيادة كفاءة المنظومة.تم اختيارللسيطرة على القدرة الخارجة للمحول (p&o)تعتمد على خوارزمية تغيرات االشعاع الشمسي ودرجة الحرارة للخلية للنموذج والتي تتأثر ب ) p-v i-v,p-iالحصول على الخصائص الكهربائية (المنحنيات المنظومة، حيث تم 17vان اعظم قدرة تم الحصول عليها هي عند الفولتية . الشمسي ألي تغير في درجة حرارة المحيط واالشعاع ارمستقالضوئية. وجد النموذج المقترح ,9v:2a, 5v:1a)، وان النتائج التقريبية التي تم الحصول عليها للفولتيات والتيارات للمخارج المتعددة هي mpptعند استخدام المسيطر 3.5aوالتيار 2.2v:0.5a) ُفي تصميم انظمتهم التي تتطلب نموذجين والخبراء جدا للمهندسين والباحث . أن النموذج المقترح مفيد ً ً بسيط ا للخاليا الشمسية. اودقيق ا ieee paper word template in a4 page size (v3) al-khwarizmi engineering journal al-khwarizmi engineering journal,vol. 12, no. 2, p.p. 4559 (2016) energy and exergy analysis on modified closed wet cooling tower in iraq qasim saleh mahdi * hayder mohammad jaffal ** *department of mechanical engineering/ al-mustansiriyah university * department of environmental engineering/ al-mustansiriyah university *e-mail: qasim602006@yahoo.com **e-mail: hayder.jaffal@yahoo.com (received 3 september 2015; accepted 12 january 2016) abstract the present study involves experimental analysis of the modified closed wet cooling tower (cwct) based on first and second law of thermodynamics, to gain a deeper knowledge in this important field of engineering in iraq. for this purpose, a prototype of cwct optimized by added packing under a heat exchanger was designed, manufactured and tested for cooling capacity of 9 kw. experiments are conducted to explore the effects of various operational and conformational parameters on the towers thermal performance. in the test section, spray water temperature and both dry bulb temperature and relative humidity of air measured at intermediate points of the heat exchanger and packing. exergy of water and air were calculated by applying the exergy destruction method on the cooling tower. experimental results showed a significant performance improvement when using packing on the cwct. it can be observed that the thermal efficiency for the cwct with packing under a heat exchanger and cwct with packing above the heat exchanger are approximately 40% and 25% higher than that of the cwct without packing respectively. as another part of the experiment results, it is indicated that the exergy destruction is directly proportional to air flow rate, cooling water flow rate, inlet cooling water flow rate and inlet air wet bulb temperature (awbt) whereas, it is inversely proportional with spray water flow rate. in comparison with the cooling capacity of the tower, it was found that the exergy destruction approximately less than 20%. exergy efficiency behavior is inversely proportional with the behavior of the exergy destruction. empirical correlations are obtained to predict water film heat transfer coefficient and air water mass transfer coefficient considering the influences of operational parameters. keywords: closed wet cooling tower (cwct), exergy, packing, thermal performance. 1. introduction there are two types of wet cooling towers: open and closed cooling towers. in the open cooling tower, the water is in direct contact with the air at surface of the packing. in conventional cwcts recirculated water is sprayed over a horizontal tube bundle, while air is drawn over the bundle and the cooling water is circulated in tubes and never contacts the outside air. the advantage of cwct is the limited of pollution dangers with airborne dusts as well corrosion. it has a wide range of applications in the fields of electrical power, chemical industry and building air conditioning. with more and more closed cooling tower applications, the study also received increasing attention [1]. much attention has been paid to issues on cwcts relating to experimental studies and developed correlations of heat and mass transfer coefficients as a function of operating conditions. armando & facao [2], designed a new cwct in order to examined effects of the operating parameters on the saturation efficiency for a cwct modified for use with chilled ceilings in buildings. qureshi & zubair [3], presented theoretically a thermodynamic analysis of counter flow wet cooling towers and evaporative heat exchangers using both the first and second law of thermodynamics. by applying an exergy balance on each of the systems, the variation of secondmailto:hayder.jaffal@yahoo.com qasim saleh mahdi al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 4559(2016) 46 law efficiency as well as exergy destruction as a function of various input parameters such as inlet awbt & inlet water temperature has been identified. shim et al. [4&5], investigated experimentally the thermal performance of two heat exchangers in closed-wet cooling tower having a rated capacity of 2 tr. both heat exchangers have multi path that is consumed as the entrance of cooling water and are consisting of bare-type copper tubes of 15.88 mm and 19.05 mm. heyns & kroger [6], investigated the thermal performance characteristics of an evaporative cooler, which consist of 15 tube rows with 38.1 mm outer diameter galvanized steel tubes arranged in a triangular pattern of 76.2 mm. zheng et al [7], investigated thermal performance of an oval tube cwct based on heat and mass transfer under different operating conditions. ramkumar and ragupathy [8], have been investigated thermal performance of open type mechanical draft counter flow cooling tower with expanded wire mesh packing. exergy analysis has been applied to study the cooling tower potential of performance using the psychometric gun technique. in the relevant literature, no results have been reported so far involving the performance of cwct with packing. the aim of this research is to evaluate thermal performance of modified cwct with added packing based on first and second law of thermodynamics in iraq. 2. experimental apparatus and procedure 2.1. description of test rig a new counter flow cwct was designed and constructed in which different operating parameters could be varied and tested in the laboratories of environmental engineering department of al-mustansiriyah university, college of engineering. the general arrangement of the equipment is shown in figure (1). in general, the apparatus consists essentially of cooling column and three major systems; spray water, cooling water and air blowing. the tower fabricated from galvanized steel sheet to provide protection from rusting and corrosion, each sheet of 1.5 mm thickness, connected together by screws and nuts as a rectangular box of external dimensions 420 mm in width, 760 mm in depth and 280 mm in height, mounted rigidly on a frame which is welded construction with a channel section at the base welded together from the rectangle. as exists in every forced cooling, the test section consists of three zones: spray, fill (cooling zone) and rain zone. spray zone is at a height of 180 mm suitable to ensure water distribution uniformly to all points in the fill section. fill zone at 1000 mm height and characterized as consisting of three places for sliding removable drawer rectangular boxes at the same dimensions, manufacturing for packing and heat exchangers to ensure change the locations and types of heat exchangers and height of packing to study the influence of all these additions on the performance of the tower. the rectangular drawer made of galvanized steel with dimensions of 420 mm in width, 760 mm in depth and 280 mm in height. six holes along the side of each (drawer) box were done to measure the water temperature, air dry bulb temperature and air relative humidity. the rain zone at a height of 450 mm in the case of three boxes and it will be variable when lifting one or two packing’s and increases as decreases the packing height. air from the atmosphere, enters the single stage centrifugal blower at a rate which is controlled by the butterfly valve. the fan discharges into the pvc pipe and the entrance duct before entering the packed column. as the air flows through the packing and heat exchanger, its moisture content increases and the water in the heat exchanger are cooled. hot water is pumped from the load tank through the control valve and a water flow meter to the heat exchanger placed inside the test section of tower. plain tube heat exchanger was designed and manufactured for the present work. the tubes were fixed horizontally in test section inside supported frame of rectangular drawer. qasim saleh mahdi al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 4559(2016) 47 fig.1. photographic picture for experimental apparatus (lateral view). cooling water moves through the tubes while the spray water and air move over the tubes in perpendicular direction. the tubes are arrayed in staggered arrangement with (equilateral) tube pitch of 3do (pitch over diameter of 3).the specification of heat exchangers shows in table (1). table 1, physical dimension of heat exchanger. heat exchanger configuration value unit length (l1) 690 mm height (l2) 166 mm width (l3) 381 mm number of tubes for coil 30 vertical tube spacing (xl) 24 mm horizontal tube spacing (xt) 80 mm tube per row 5 outside tube diameter 15.88 mm tube thickness 0.81 mm total heat transfer area 1032691.77 mm2 minimum free flow area 209148 mm2 the basic geometry for an idealized single pass cross flow tubular (bar type) exchanger with staggered tube arrangement is shown in figure (2). fig. 2. tubular single pass exchanger with staggered tubes arrangement [9]. in the present study, 18 sheets with area of (760 ⨯ 280 mm 2 ) film type fills consist of vertical corrugated sheets arranged vertically forming an angle relative to one another of 45 ̊ viewed in the main direction of flow of the air. the sheets are joined to make rectangle units were fixed in test section inside supported frame of rectangular drawer. for better cooling performance, corrugated film packing were tested in different location arrangement with heat exchanger at a height of 280 mm and 560 mm. the water distribution system in the cooling tower should distribute the water uniformly over the tube bundle and packing inside the tower, to be the most coefficient method of uniform water distribution in counter flow wet-cooling tower a flow xt /2 l2 xt l3 xl x l /2 do di water filter air blower butterfly valve excuse duct cooling column temperature recorders qasim saleh mahdi al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 4559(2016) 48 pressurized spray system used with different types of spray nozzles. the spray water passes through the spray nozzles and constantly distributed at the upper part of the test section, controlled by means of flow control valve globe type located downstream of the spray water pump. the water distribution system, for the purpose of this study, consists of a spray head (25.4 mm pipe) and six nozzles. the nozzles mounted on branching pipes, of 125 mm each, from the main pipe and the same diameter as the main. the length of the whole arrangement of pipes is 800 mm. the spray head is designed to gives two sets of nozzles; each set consists of three nozzles and pointed to a direction opposite to the other set. this would give a net distance of 130 mm between the centres of each two adjacent nozzles. figure (3) shows the spray nozzles arrangement. fig. 3. spray nozzles arrangement. 2.2. test procedure in order to evaluate the thermal performance of cooling tower, a series of experiments was carried out at different operational and conformational parameters. operational parameters demonstrate: air flow rate of (0.12-0.3) kg/s, spray water flow rate of (20,25,30,35,40,45) l/min, cooling water flow rate of (10,15,20,25,30,35,40,45,50) l/min, inlet cooling water temperature of (35,40,45,50,55) ̊ c and inlet awbt of (7-24) ̊ c. conformational parameters indicate: height of packing used (560) mm, location of packing (under heat exchanger and above heat exchanger). thermocouples type k inserted before and after the cooler coil to measured cooling water temperature. to measure the spray water temperatures at intermediate locations inside test section, especially channels have been manufacturing to insert thermocouples through holes. these holes are closed by rubber stoppers through which thermocouples are inserted to measure the temperature profile. the variations of air dry bulb temperature and relative humidity along the test section as well as the inlet and outlet of the tower were measured by humidity meter, which combined temperature/humidity sensor. the humidity meter model th-305 has a (main faction) temperature and relative humidity measurement range from 0 to 60 ̊ c and 20 to 95% respectively. the sensor probe handle is placed directly in the air stream and connected to display. fig. 4. locations of thermocouples and humidity meter in the test rig. (ta&rh)12 (ta&rh)9 (ta&rh)10 (ta&rh)11 (ta&rh)6 (ta&rh)7 (ta&rh)8 tw13 air out air in tw1 tw2 tw3 tw4 tw5 tw6 tw7 tw8 tw9 tw10 tw11 tw12 tw14 t15 tw16 tw17 (ta&rh)1 (ta&rh)2 (ta&rh)3 (ta&rh)4 (ta&rh)5 qasim saleh mahdi al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 4559(2016) 49 2.3. performance parameters 2.3.1. energy analysis in viewpoint of energy analysis, the parameters used to determine the performance of cooling tower are: 1cooling range: is the temperature difference between the water inlet and exit states. range can be measured by the temperature difference between the inlet and outlet from cooling tower: 𝐶𝑅 = 𝑇𝑐𝑤 ,𝑖𝑛 − 𝑇𝑐𝑤 ,𝑜𝑢𝑡 … (1) 2thermal efficiency: the most important parameter of cooling tower performance is the thermal efficiency, which can be defined as the ratio of actual released of heat to the maximum theoretical heat from cooling tower. the thermal efficiency for the closed circuit cooling towers was defined as [2&10]: 𝜂 = 𝑇𝑐𝑤 ,𝑖𝑛 − 𝑇𝑐𝑤 ,𝑜𝑢𝑡 𝑇𝑐𝑤 ,𝑖𝑛 − 𝑇𝑎𝑤𝑏 ,𝑖𝑛 . . . (2) 3cooling capacity: is the heat rejected or heat dissipation, given product of mass flow rate of water, specific heat and temperature difference. 𝑞 = 𝑚 𝑐𝑤𝐶𝑝 ,𝑐𝑤 𝐶𝑅 . . . (3) 4-mass transfer coefficient: the mass transfer coefficient obtained using enthalpy balance for an elementary transfer surface [2]. 𝑚𝑎𝑑𝑕𝑎 = 𝛼𝑚 𝑕𝑖 − 𝑕𝑎 𝑑𝐴 . . . (4) which is known as the merkel equation and integrated for the whole heat exchanger in tower gives: 𝛼𝑚𝐴 𝑚 𝑎 = 𝑙𝑛 𝑕𝑖 − 𝑕𝑎 ,𝑖𝑛 𝑕𝑖 − 𝑕𝑎 ,𝑜𝑢𝑡 . . . (5) where, αm is the mass transfer coefficient for water vapor between spray water film an air , a is the surface area of the heat exchanger and hi is the specific enthalpy of the saturated air at the mean spray water temperature . the average of spray water temperatures was taken as the interface temperature according to [7] while the inlet and outlet air enthalpies were calculated from psychometric chart according to the measured data. outlet air enthalpy could be also calculated considering that all the heat goes from water to air [11] 𝑚 𝑎 𝑕𝑎 ,𝑜𝑢𝑡 − 𝑕𝑎 ,𝑖𝑛 = 𝑚 𝑐𝑤𝐶𝑝 ,𝑐𝑤 (𝑇𝑐𝑤 ,𝑖𝑛 − 𝑇𝑐𝑤 ,𝑜𝑢𝑡 ) . . . (6) then the outlet air enthalpy calculates as: 𝑕𝑎 ,𝑜𝑢𝑡 = 𝑕𝑎 ,𝑖𝑛 + 𝑚 𝑐𝑤 𝐶𝑝 ,𝑐𝑤 (𝑇𝑐𝑤 ,𝑖𝑛−𝑇𝑐𝑤 ,𝑜𝑢𝑡 ) 𝑚 𝑎 . . . (7) 5-heat transfer coefficient: heat transfer from cooling water inside tubes to spray water and air through a water film .the rate of heat transfer from cooling water dqc is given by [12]: 𝑑𝑞𝑐 = 𝑚 𝑐𝑤𝐶p,𝑐𝑤𝑑𝑇𝑐𝑤 = −𝑈𝑜 𝑇𝑐𝑤 − 𝑇𝑠𝑤 𝑑𝐴 . . . (8) integrated eq.(8) from the inlet to outlet of cooling water, with constant spray water tsw, gives. 𝑈𝑜𝐴𝑐 𝐶𝑝 ,𝑐𝑤𝑚𝑐𝑤 = 𝑙𝑛 𝑇𝑐𝑤 ,𝑖𝑛 − 𝑇𝑠𝑤 ,𝑚 𝑇𝑐𝑤 ,𝑜𝑢𝑡 − 𝑇𝑠𝑤 ,𝑚 . . . (9) where, uo is the overall heat transfer coefficient between cooling water inside the tubes, tube wall and spray water on the outside .it is calculated by the following formula [4]: 𝑈𝑜 = 𝑅𝑜 𝑅𝑖 1 𝛼𝑐 + 𝑅𝑜 𝑘𝑡 𝑙𝑛 𝑅𝑜 𝑅𝑖 + 1 𝛼𝑠 −1 . . . (10) after the overall heat transfer coefficient was calculated from eq.(9), it used to calculate, αs, tube to water film heat transfer coefficient (w/m 2 c). 𝛼𝑠 = 1 𝑈𝑜 − 𝑅𝑜 r𝑖 1 𝛼𝑐 − 𝑅𝑜 ktube ln 𝑅𝑜 𝑅𝑖 −1 . . . (11) where, αc is the convection heat transfer coefficient of cooling water inside the tubes, it was calculated by the “dittuse-boelter” relation [13]: 𝛼𝑐 = 0.023 𝑘𝑐𝑤 𝐷𝑖 𝑅𝑒0.8 𝑃𝑟0.3 . . . (12) where, reynolds number and prandtl number were taken for the cooling water inside the tubes. 2.3.2. exergy analysis in this study, the exergy analysis of the cwct based on the exergy destruction method (edm) was carried out in the simplified system shown in figure (5), where the dray air enters the test section from the bottom at the input conditions and crosses the test section at the output conditions while spray water opposed the air direction. on the other hand, cooling water enters the test section inside the heat exchanger perpendicular to the direction of both air and spray water and come out the opposite of entering heat exchanger. for steady state conditions (operating cooling tower), neglecting the effect of kinetic and potential energy, an exergy balance is formulated for all components of the cwct were presented in figure (5). qasim saleh mahdi al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 4559(2016) 50 fig. 5. exergy balance of the cooling tower. 1-exrgy of water exergy of water can be obtained by bejan [14]: 𝐸𝑋𝑤 ° = 𝑚𝑤 ° 𝑕𝑓𝑤 − 𝑕𝑓𝑜 + 𝑇𝑜 𝑆𝑓𝑤 − 𝑆𝑔𝑜 − 𝑅𝑣𝑇𝑜 𝑙𝑛∅𝑜 . . . (13) neglected the mechanical exergy of water comparing with chemical exergy, so the exergy of water for ideal gas law, eq . (13) becomes: 𝐸𝑋𝑤 ° = 𝑚𝑤 ° 𝐶𝑃𝑤 𝑇 − 𝑇𝑜 − 𝑇𝑜𝐶𝑃𝑤 𝑙𝑛 𝑇 𝑇𝑜 − 𝑅𝑣𝑇𝑜 𝑙𝑛∅𝑜 . . . (14) 2exergy of humid air the total exergy in the psychometric process – such as in the cooling tower operating mechanism, without the effect of kinetic and potential energy, on the bases of dray air and water vapour as an ideal gas when neglecting the change of pressure through the cooling tower in the steady state –can thus be generally represented presented in bejan[14]: 𝐸𝑋𝑎 ° = 𝑚𝑎 ° 𝐶𝑃𝑎 + 𝜔𝐶𝑃𝑣 𝑇 − 𝑇𝑜 − 𝑇𝑜 𝑙𝑛 𝑇 𝑇𝑜 + 𝑅𝑎𝑇𝑜 1 + 1.608𝜔 𝑙𝑛 1 + 1.608𝜔𝑜 1 + 1.608𝜔 + 1.608𝜔𝑙𝑛 𝜔 𝜔𝑜 . . . (15) 3. exergy destruction an exergy balance states that the total exergy increases or decreases within the system boundary plus the exergy destruction within the same boundary equals the difference between the total exergy transfers in and out across the boundary. exergy destruction represents by the difference between exergy change of water and exergy change of air. 𝐸𝑋𝑖𝑛 ° − 𝐸𝑋𝑜𝑢𝑡 ° − 𝐸𝑋𝑑 ° = 0 . . . (16) the exergy destruction can be determined by: 𝐸𝑋𝑑 ° = 𝐸𝑋𝑎,𝑖𝑛 ° + 𝐸𝑋𝑠𝑤 ,𝑖𝑛 ° + 𝐸𝑋𝑐𝑤 ,𝑖𝑛 ° + 𝐸𝑋𝑤 ,𝑚𝑎𝑘𝑒𝑢𝑝 ° − 𝐸𝑋𝑎 ,𝑜𝑢𝑡 ° + 𝐸𝑋𝑠𝑤 ,𝑜𝑢𝑡 ° + 𝐸𝑋𝑐𝑤 ,𝑜𝑢𝑡 ° . . . (17) 4. exergy efficiency the exergy efficiency (second low efficiency), which is measured of irreversibility losses in a given process is define as [15]: 𝜂𝐸𝑥 = 1 − 𝐸𝑋𝑑 ° 𝐸𝑋𝑖𝑛 ° … 18 3. results and discussions 3.1. influence of air and spray water flow rates the effect of air flow rate on the cooling capacity for different values of the spray water rate is illustrated in figure (6). for each value of spray flow rate, as the air flow rate increases; the cooling water range is increases, cooling capacity increased. this can be explained by as the air flow rate increases, rate of evaporated water increases too causing an increasing in the water cooling range. on the other hand, a proportional relation has been shown between the cooling capacity and the spray water flow rate, for the different values of air flow rates. the most important reason for increasing cooling capacity with spray water flow rate is increasing a contact surface for the mass and heat transfer between water and air. the effect of air flow rate on thermal efficiency for different spray water flow rates illustrated in figure (7). the cooling tower thermal efficiency increases with the increase of air flow rate and spray water flow rate due to the increase in cooling range and the decrease in tower approach as its calculation from eq. (3). this behaviour was observed by yoo et. al. (2010), [16]. cooling tower ex˙a,in ex˙sw,out ex˙a,out ex˙sw,in ex˙cw,in ex˙cw,out ex˙w,makeu p qasim saleh mahdi al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 4559(2016) 51 fig. 6. variation of cooling capacity with spray water flow rate for different air flow rates. fig. 7. variation of thermal efficiency with spray water flow rate for different air flow rates. the effect of air flow rate on exergy destruction for different spray water flow rates illustrated in figure (8). exergy destruction represents by the differences between exergy changes of water and exergy changes of air. for a fixed spray water flow rate, it is observed that the overall cooling tower exergy destruction increases with the increase of the air flow rate due to increase in rate of evaporation losses that causes an increasing in exergy of makeup water. on the other hand, exergy destruction decreases as spray water flow rate increases. fig. 8. variation of exergy destruction with spray water flow rate for different air flow rates. the effect of air flow rate on exergy efficiency for different spray water flow rates illustrated in figure (9). it is clear that the exergy efficiency inversely proportional to the air flow rate. in other words, exergy efficiency in proportional relation with spry water flow rate. fig. 9. variation of exergy efficiency with spray water flow rate for different air flow rates. figure (10) shows total exergy change distribution of water and air with the spray water flow rate. both exergies increases slightly with the increase of spray water flow rate. as indicated in figure (10), the increasing of spray water flow rate generates an enthalpy increase lead to an increase in exergy of water. the total exergy of air is sum of convection air exergy and evaporation air exergy. also, it is indicated that the difference 2 2.5 3 3.5 4 4.5 5 15 20 25 30 35 40 45 50 m̊a=0.228 kg/s m̊a=0.195 kg/s m̊a=0.133 kg/s flow rate of spray water [ l/min ] c o o li n g c a p a ci ty [ k w ] qcw=10 l/min tcwi= 46 ̊ c tawb= 19.5 ̊ c 12 14 16 18 20 22 24 26 15 20 25 30 35 40 45 50 m̊a=0.228 kg/s m̊a=0.195 kg/s m̊a=0.133 kg/s flow rate of spray water [ l/min ] t h er m a l ef fi ci en c y [ % ] qcw=10 l/min tcwi= 46 ̊ c tawb= 19.5 ̊ c 99 99.1 99.2 99.3 99.4 99.5 99.6 99.7 99.8 20 25 30 35 40 45 m̊a=0.228 kg/s m̊a=0.195 kg/s m̊a=0.133 kg/s flow rate of spray water [ l/min ] e x er g y e ff ic ie n c y [ % ] qcw=10 l/min tcwi= 46 ̊ c 0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.6 20 25 30 35 40 45 m̊a=0.228 kg/s m̊a=0.195 kg/s m̊a=0.133 kg/s flow rate of spray water [ l/min ] e x er g y d es tr u ct io n [ k w ] qcw=10 l/min qasim saleh mahdi al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 4559(2016) 52 between total exergy change of water and air increases with increasing in spray water flow rate. fig. 10. variation of total exergy change of water and air with spray water flow rate. 3.2. influence of cooling water flow rate the cooling capacity of tower versus cooling water flow rate with different spray water flow rates is shown in figure (11). it can be noticed that the cooling capacity is proportional with cooling and spray water flow rates. for each spray water flow rates, cooling capacity increases significantly to increase in cooling water flow rate according to eq. (3). fig. 11. variation of cooling capacity with cooling water flow rate for different spray water flow rates. the effect of cooling water flow rate on thermal efficiency for different spray water flow rates illustrated in figure (12). thermal efficiency is inversely proportional to the cooling water flow rate. at low cooling water flow rate, the opportunity to be the largest in completion of heat exchange caused an increasing in temperature difference of cooling water and thermal efficiency. fig. 12. variation of thermal efficiency with cooling water flow rate for different spray water flow rates. the effect of cooling water flow rate on exergy destruction for different spray water flow rates illustrated in figure (13). as discussed in previous figure, when spray water flow rate increases exergy destruction decreases, whereas in this figure, it is state that the exergy destruction increases while cooling water flow rate increases due to increase in total water exergy. the exergy of cooling water depends mainly on the cooling water flow rate, so any increase in cooling water flow rate causes an increase in total exergy of water. fig. 13. variation of exergy destruction with cooling water flow rate for different spray water flow rates. 0 0.2 0.4 0.6 0.8 1 1.2 15 20 25 30 35 40 45 50 δex ̊water δex ̊air flow rate of spray water [ l/min ] e x er g y ch an g e [k w ] m̊a=0.22 kg/s qcw=10 l/min tcwi= 46 ̊ c 3 4 5 6 7 8 9 10 0 5 10 15 20 25 30 35 40 45 50 55 qsw=40 l/min qsw=30 l/min flow rate of cooling water [ l/min ] c o o li n g c a p ac it y [ k w ] m̊a=0.22 kg/s tcwi= 46 ̊ c tawb= 20 ̊ c 0 5 10 15 20 25 30 0 5 10 15 20 25 30 35 40 45 50 55 qsw=40 l/min qsw=30 l/min flow rate of cooling water [ l/min ] t h er m a l ef fi ci en c y [ % ] m̊a=0.22 kg/s tcwi= 46 ̊ c 0.2 0.3 0.4 0.5 0.6 0.7 0.8 10 15 20 25 30 35 40 45 50 qsw=40 l/min qsw=30 l/min flow rate of cooling water [ l/min ] e x er g y d es tr u ct io n m̊a=0.22 kg/s tcwi=46 ̊ c twbi=20 ̊c qasim saleh mahdi al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 4559(2016) 53 the effect of cooling water flow rate on exergy efficiency for different spray water flow rates illustrated in figure (14). from this figure, it can be seen that the exergy efficiency decreases when cooling water flow rate increased and spray water flow rate decreased. fig. 14. variation of exergy efficiency with cooling water flow rate for different spray water flow rates. the relationship between the total exergy change of water and air with cooling water flow rate is illustrated in figure (15). it could be clearly seen that the total exergy change of water and air are proportional to the cooling water flow rate. as expected, the total exergy change of water increases with the increases in cooling water flow rate as a result of increasing in exergy of cooling water. also, it could be seen that the difference between total exergy change of water and air increases with increasing in cooling water flow rate. fig. 15. variation of total exergy change of water and air with cooling water flow. 3.3. influence of inlet cooling water temperature cooling capacity with respect to variable inlet cooling water temperature and spray water flow rate has been shown in figure (16). it is shown that if the spray water flow rate remains constant, cooling capacity increases rapidly with the increase of inlet cooling water temperature due to increase in rate of heat and mass transfer. this behaviour is determined by different experiments of authors shim et. al. (2008), [4] and yoo et. al. (2010), [16]. fig. 16. variation of cooling capacity with inlet cooling water temperature for different spray water flow rates. figure (17) indicate the effect of variable inlet cooling water temperature upon the tower thermal efficiency for different values of spray water flow rates. the thermal efficiency increases almost exponentially as the inlet cooling water temperature increases for all values of spray water flow rates. the thermal efficiency is high at higher inlet cooling water temperature and spray water flow rate. small increment at low water temperature will gradually increases with an increase in water temperature. figure (18) depicts the effect of inlet cooling water temperature upon the overall exergy destruction for different values of spray water flow rates. as mentioned in figure (8), for fixed inlet cooling water temperature, exergy destruction in inversely proportional to the spry water flow rate. on the other hand, from figure (18), it was observed that by increasing inlet cooling water temperature, the exergy destruction increased due to increasing difference between 99.1 99.15 99.2 99.25 99.3 99.35 99.4 99.45 99.5 99.55 99.6 10 15 20 25 30 35 40 45 50 qsw=40 l/min qsw=30 l/min flow rate of cooling water [ l/min ] e x er g y e ff ic ie n c y [ % ] m̊a=0.22 kg/s tcwi= 46 ̊ c tawb= 20 ̊ c 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0 5 10 15 20 25 30 35 40 45 50 55 δex ̊water δex ̊air flow rate of cooling water [ l/min ] e x er g y ch a n g e [k w ] m̊a=0.22 kg/s qsw= 30 l/min tcwi= 46 ̊ c 1 2 3 4 5 6 7 8 30 35 40 45 50 55 60 qsw=45 l/min qsw=35 l/min qsw=25 l/min inlet cooling water temperature [ ̊c ] c o o li n g c a p a ci ty [ k w ] m̊a=0.22 kg/s qcw=10 l/min tawb= 19.5 ̊ c qasim saleh mahdi al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 4559(2016) 54 inlet water temperature and environmental air temperature which lead to increase thermal exergy of water. also, increasing inlet water temperature causes an increase in the difference between the inlet and outlet cooling water temperature and thermal exergy of outlet cooling water increase too. fig. 17. variation of thermal efficiency with inlet cooling water temperature fort different spray water flow rates. fig. 18. variation of exergy destruction with inlet cooling water temperature for different spray water flow rates. the effect of cooling water flow rate on exergy efficiency for different spray water flow rates illustrated in figure (19). the exergy efficiency decreases when cooling water flow rate increased and spray water flow rate decreased. the variation of total exergy change of water and air with inlet cooling water temperature is illustrated in figure (20). it is indicated from this figure that the total exergy change of water and air increases exponentially with the increase of inlet cooling water temperature. as inlet cooling water temperature increases, inlet exergy of cooling, spray and makeup water increases lead to increase total exergy change of water. also, it is shown that the difference between total exergy change of water and air increases with increasing in inlet cooling water temperature. fig. 19. variation of exergy efficiency with inlet cooling water temperature for different spray. fig. 20.variation of total exergy change of water and air with inlet cooling water temperature. 3.4. influence of inlet awbt the change in cooling capacity versus inlet awbt for different inlet cooling water temperature presented in figure (21). it is clear that the cooling capacity in inversely proportional with the inlet awbt for both inlet cooling water 12 14 16 18 20 22 24 26 28 30 30 35 40 45 50 55 60 qsw=45 l/min qsw=35 l/min qsw=25 l/min inlet cooling water temperature [ ̊c ] t h er m al e ff ic ie n cy [ % ] m̊a=0.22 kg/s qcw=10 l/min tawb= 19.5 ̊ c 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 35 40 45 50 55 qsw=45 l/min qsw=35 l/min qsw=25 l/min inlet cooling water temperature [ ̊c ] e x er g y d es tr u ct io n m̊a=0.22 kg/s qcw=10 l/min tawb= 19.5 ̊ c 98.9 99 99.1 99.2 99.3 99.4 99.5 99.6 99.7 99.8 35 40 45 50 55 qsw=45 l/min qsw=35 l/min qsw=25 l/min inlet cooling water temperature [ ̊c ] e x er g y e ff ic ie n c y [ % ] m̊a=0.22 kg/s qcw=10 l/min tawb= 19.5 ̊ c 0 0.2 0.4 0.6 0.8 1 1.2 1.4 30 35 40 45 50 55 60 δex ̊water δex ̊air inlet cooling water temperature [ ̊c ex er gy c ha ng e [k w ] m̊a=0.22 kg/s qsw= 45 l/min qcw=10 l/min qasim saleh mahdi al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 4559(2016) 55 temperatures. it is believed because any increase in inlet awbt reflected to decreases the enthalpy potential between saturated vapour mixture (film surrounding the water droplet) and surrounding air. the effect of inlet awbt on tower thermal efficiency for different inlet cooling water temperatures is investigated in figure (22). it can be seen for both inlet cooling water temperatures that the thermal efficiency decreased as inlet awbt increased which is brought about by the temperature fall at outlet of the heat exchanger. this behaviour was observed by sarker (2007), [17]. also, it can be apparent that higher tower thermal efficiency achieved at higher inlet cooling water temperature. fig. 21. variation of cooling capacity with inlet awbt for different inlet water temperatures. fig. 22. variation of thermal efficiency with inlet awbt for different inlet water temperatures. the effect of inlet awbt on overall exergy destruction for different inlet cooling water temperatures is investigated in figure (23). from this figure, it can be seen for both inlets cooling water temperatures that the exergy destruction depends strongly on the inlet awbt. the increases in exergy destruction with the inlet awbt correspond to an increasing in both rate of evaporation losses and dead temperature by increasing of awbt. the effect of inlet awbt on tower exergy efficiency for different inlet cooling water temperatures is investigated in figure (24). for each value of inlet cooling water temperature, as the inlet awbt increased, the exergy efficiency is increased. higher exergy efficiency achieved at lower awbt and lower inlet cooling water temperature. fig. 23. variation of exergy destruction with inlet awbt for different inlet water temperatures. fig. 24. variation of exergy efficiency with inlet awbt for different inlet water temperatures. 0 1 2 3 4 5 6 7 8 6 9 12 15 18 21 24 27 twi=45 ̊c twi=35 ̊c c o o li n g c a p a ci ty [ k w ] inlet air wet-bulb temperature [ ̊ c ] m̊a=0.22 kg/s qcw=10 l/min 0 5 10 15 20 25 30 6 9 12 15 18 21 24 27 twi=45 ̊c twi=35 ̊c t h er m a l ef fi ci en c y [ % ] inlet air wet-bulb temperature [ ̊ c ] m̊a=0.22 kg/s qcw=10 l/min 0 0.1 0.2 0.3 0.4 0.5 0.6 7.5 9.3 10.5 16 18.5 20 22.5 24 tcwi=45 ̊c tcwi=35 ̊c inlet air wet-bulb temperature e x er g y d es tr ic ti o n [ k w ] m̊a=0.22 kg/s qcw=10 l/min qsw= 40 l/min 99.45 99.5 99.55 99.6 99.65 99.7 99.75 99.8 7.5 9.3 10.5 16 18.5 20 22.5 24 tcwi=45 ̊c tcwi=35 ̊c inlet air wet-bulb temperature [ ̊ c ] e x er g y e ff ic ie n c y [ % ] m̊a=0.22 kg/s qcw=10 l/min qasim saleh mahdi al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 4559(2016) 56 effect of inlet awbt on total exergy change of water and air is shown in figure (25). the total exergy change of water is proportional to the inlet awbt due to increase in exergy of makeup water caused by increases in evaporation losses, whereas, the total exergy of air increases with increase inlet awbt before (19 ̊ c) then decreases with increase awbt due to decreases in exergy of air via convection . also, it is shown that the difference between total exergy change of water and air increases with increasing in inlet air wet bulb temperature. fig. 25. variation of total exergy change of water and air with inlet awbt. 3.5. influence of added packing figure (26) shows the cooling capacity comparing for different positions of packing. the result indicated that the cooling capacity for cwct with packing lower under heat exchanger and cwct with packing above heat exchanger approximately (28%) & (16%) higher than that cwct respectively. in figure (27), the thermal efficiency enhancement for different positions of packing is illustrated. it can be observed that the thermal efficiency for cwct with packing lower under heat exchanger and cwct with packing above heat exchanger approximately (52%) & (25%) higher than that cwct respectively. fig. 26. variation of cooling capacity with cooling water flow rate for different locations of packing. fig. 27. variation of thermal efficiency with cooling water flow rate for different locations of packing. 3.6. empirical correlations according to the results of the experiments of this work, for different operational parameters, correlations for heat and mass transfer coefficients were developed for cooling tower operates without packing. these correlations are: a-mass transfer coefficient 𝛼𝑚 = 0.000001 𝐺𝑎 0.5038 𝐺𝑠𝑤 0.7456 𝑇𝑐𝑤 2.4478 … (19) b-heat transfer coefficient 𝛼𝑠 = 0.1349 𝐺𝑠𝑤 0.3758 𝐺𝑐𝑤 0.2051 𝑇𝑐𝑤 1.7749 … (20) the average roots square mean error between correlations and experimental data for mass and heat transfer was (0.9666), (0.9424) respectively. 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 6 9 12 15 18 21 24 27 δex ̊water δex ̊air inlet air wet-bulb temperature [ ̊ c ] e x er g y ch a n g e m̊a=0.22 kg/s qcw=10 l/min 1 2 3 4 5 6 7 8 9 10 0 5 10 15 20 25 30 35 40 45 50 55 packing under heat exchanger packing above heat exchanger without packing flow rate of cooling water [ l/min ] c o o li n g c a p a ci ty [ m̊a=0.22 kg/s qsw=40 l/min tcwi= 46 ̊ c 1 6 11 16 21 26 31 0 5 10 15 20 25 30 35 40 45 50 55 packing under heat exchanger packing above heat exchanger without packing flow rate of cooling water [ l/min ] t h er m a l ef fi ci en c y [ % m̊a=0.22 kg/s qsw=40 l/min tcwi= 46 ̊ c qasim saleh mahdi al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 4559(2016) 57 4. conclusions thermal performance of cwct with packing under heat exchanger was studied experimentally in view of energy and exergy analysis. the results can be summarized as follows: 1. exergy destruction is directly proportional with air flow rate, cooling water flow rate, inlet cooling water flow rate and inlet awbt whereas, it is inversely proportional with spray water flow rate. the behavior of exergy efficiency is completely opposite to the exergy destruction behavior. 2. exergy change of water is greater than the exergy of air as a result of absorbing energy by water more than that by air because as the heating capacity of water is more and twice as much as that of the air. also, exergy of air due to an evaporation more dominated function in the air exergy due to a convection. 3. 3-cooling capacity increases when the air flow rate , spray water flow rate , cooling water flow rate and inlet cooling water temperature whereas, it decreases with an increase in awbt. a comparison of the cooling capacity of the tower, it was found that the exergy destruction approximately less than 20%. 4. 4-the cwct with packing has a better performance than without packing. comparing cwct with packing for both locations under and above heat exchanger, it has been observed that the best performance for the cwct with packing under heat exchanger. thermal efficiency for cwct with packing under heat exchanger and cwct with packing above heat exchanger approximately 40% and 25% higher than that cwct without packing respectively nomenclature a total heat transfer area, m2 cp specific heat at constant pressure, kj/kg oc cr cooling range, oc d tube diameter, m g mass flux, kg/m2.s h specific enthalpy, kj/kg k thermal conductivity, w/m oc e𝑋𝑑 exergy destruction, kw 𝑚 mass flow rate, kg/s q cooling capacity, kw q volume flow rate, l/min pr prandtl number r tube radius, m ra individual gas constant for air, j/kg.k rv individual gas constant for water vapor, j/kg.k re reynolds number s specific entropy of saturated liquid water, j/kg.k t temperature, oc uo overall heat transfer coefficient, w/m2 oc greek symbols αm mass transfer coefficient for water vapour, between spray water film and air, kg/m2 s αs heat transfer coefficient between tube external surface and spray water film, w/m2 oc αc heat transfer coefficient for water inside the tubes, w/m2 oc η thermal efficiency, % ηex exergy efficiency, % 𝜌 density, kg/m3 φ relative humidity, % ω humidity ratio, kg/kgdry air subscripts a air cw cooling water in inlet o dead state out outlet sw spray water t tube references [1] pascal stabat, and dominique marchio. 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[16] yoo seong-yeon, jin-hyuck kim, and kyu-hyun han. (2010). thermal performance analysis of heat exchanger for closed wet cooling tower using heat and mass transfer analogy. journal of mechanical science and technology, vol.24, no.4, pp (893-898). [17] sarker m. m. (2007). investigation on the optimum design of heat exchangers in a hybrid closed circuit cooling tower. journal of mechanical engineering, vol. 37, pp (52-57). (2016) 4559، صفحة 2، العذد12دجلة الخىارزهً الهنذسٍة الوجلملاسن صالح ههذي 59 تحلٍل الطالة والطالة الوتاحة على برج تبرٌذ رطب هغلك هطّىر فً العراق لاسن صالح ههذي * حٍذر هحوذ جفال ** اٌدبِعخ اٌّسزٕصسٌخ /وٍٍٗ إٌٙدسخ /لسُ إٌٙدسخ اٌٍّىبٍٔىٍخ* اٌدبِعخ اٌّسزٕصسٌخ /وٍٍٗ إٌٙدسخ /لسُ ٕ٘دسٗ اٌجٍئخ ** qasim602006@yahoo.com : اٌجسٌد االٌىزسًٚٔ* hayder.jaffal@yahoo.com البريد االلكتروني: ** لخالصةا ِٓ أخً شٌبدح اٌّعسفخ فً ٘را اٌحْمً األٚي ٚاٌثبًٔ اٌدٌٕبٍِه اٌحسازٌخفك لبًٔٛٔ عٍى ثسج رجسٌد زطت ِغٍك ِطٛز ياٌدزاسخ رحٍٍالً عٍٍّبً ٘رٖ رزضّٓ ز ٌجسج رجسٌد ِغٍك زطت ثإضبفخ حشٛاد ٌسعخ رجسٌدا صُّ ٚصٕع ٚاخزجسٌٙرا اٌغسض .إٌٙدسً اٌُّٙ فً اٌعساق ّٛ أخسٌذ . (وٍٍٛ ٚاط 9) ّٔٛذج ِط حسازح ايِٓ دزخخ اٌسش ٚوًاء دزخخ حسازح َرجبز ٚفً ِمطع االخ. ٌحسازي ٌٍجسجٌزٛضٍح رأثٍساد اٌّعبِالد اٌزشغٍٍٍخ ٚاٌزصٍّّخ عٍى األداء ااٌزدبزة اٌطبلخ اٌّزبحخ ٌٍّبء ٚاٌٙٛاء رُ حسبثٙب ثزطجٍك طسٌمخ رحطٍُ .رُ لٍبسٙب فً ٔمبط ِزٛسطخ ٌٍّجبدي اٌحسازي ٚاٌحشٛح اٌزً اٌدبفخ ٚاٌسطٛثخ إٌسجٍخ ٌٍٙٛاء األداء حرُ ِالحظٚ. إٌزبئح اٌزدسٌجٍخ ٚضحذ رحسٍٕبً ٍِّٛسبً ٌألداء اٌحسازي عٕد إضبفخ اٌحشٛح إٌى اٌجسج اٌّغٍك إْ .اٌطبلخ اٌّزبحخ عٍى ثسج اٌزجسٌد اٌىفبءح اٌحسازٌخ عٕد إضبفخ اٌحشٛح اسفً أْ ٚخد. ضٍبع اٌطبلخ اٌّزبحخ ٌٙرٖ اٌحبٌخاألفضً عٕد إضبفخ اٌحشٛح اسفً اٌّجبدي اٌحسازي عٍى اٌسغُ ِٓ وجس أْ اٌطبلخ ورٌه ٌٛحظ .ِمبزٔخ ِع ثسج اٌزجسٌد اٌّغٍك ثدْٚ إضبفخ اٌحشٛح عٍى اٌزٛاًٌ% 25ٚ% 4ٓٚاعٍى اٌّجبدي اٌحسازي ثأفضٍخ رصً إٌى ٔسجخ اٌٙٛاء اٌسطجخ اٌداخٍخ ٌٍٙٛاء ثٍّٕب دخٛي ٌّبء اٌزجسٌد ٚدزخخ حسازحايدزخخ حسازح ,اٌّزبحخ اٌّحطّخ رزٕبست رٕبسجبً ِجبشساً ِع ردفك اٌٙٛاء ردفك ِبء اٌزجسٌد ٚخد أْ ِٚمبزٔخ ِع سعخ اٌزجسٌد ٌٍجسج ثبي .سٍٛن وفبء اٌطبلخ اٌّزبحخ ِعبوس ٌسٍٛن ضٍبع اٌطبلخ اٌّزبحخ .رزٕبست رٕبسجب عىسٍبً ِع ِعدي ردفك ِبء اٌسش .ِزغٍساد اٌزشغٍٍٍخاي ثدالٌخ عدد ِٓ اٌعاللبد اٌزدسٌجٍخ ٌٍزجٛء ثّعبًٍِ أزمبي اٌحسازح ٚاٌىزٍخ رٕزبجاسرُ %.2ٓاٌطبلخ اٌّزبحخ اٌّحطّخ رشىً ٔسجخ الً ِٓ mailto:qasim602006@yahoo.com mailto:hayder.jaffal@yahoo.com 20-27نبيل ومالية وعباس al-khwarizmi engineering journal,vol. 13, no. 1, p.p. improvement of mechanical rubber for a nabel k. abd ali* malia. m.farhan ** department of material *,*** department of material *email: **email: **email: (received 29 june https://doi.org/10.22153/kej.2017.12.002 abstract this research aims to study and improve the passivating specifications of rubber resistant to vibration. in this paper, seven different rubber recipes were prepared based on mixtures of natural rubber(nr) as an essential part in addition to the synthetic rubber (iir, brcis, sbr, cr)with different rates. mechanical tests such as tensile strength, friction, resistance to compression, fatigue and creep testing in addition to the furthermore, scanning electron microscopy (sem)test was used to examine the structure morphology of rubber. after studying and analyzing the results, we found that, mechanical and physical specifications to be used in appli vibration. keywords: ant vibration behavior , natural rubber 1. introduction many kinds of machinery and engineering equipment suffer from vibrations and noise problems. these problems increase dramatically when there is no means to prevent vibrations or it damage after a short period. there are several ways to reduce the vibrations, control the natural frequency ,using barriers and enclosures wave vibration amplitude (through a method of effective system which include applying force with the same frequency and amplitude to the source of the vibration, but opposite phase direction and thereby the vibration force will be canceled in vibration sites ) or applying passive systems which are cheap and easily to manufactured, such as air springs , mineral springs , dampers and rubber mounts [1,2,3].rubber is a polymeric material which becomes flexible by vulcanization. due to the khwarizmi engineering journal,vol. 13, no. 1, p.p. 2027 (2017) nical and rheological properties of natural for anti-vibration applications malia. m.farhan** abbas s. moosa material engineering/ university of al-qadisiyah department of material engineering / technical college –baghdad *email: nabel.abdali@qu.edu.iq **email: malia.m.f@mtu.edu.iq email: abbassahip@gmail.com june 2016; accepted 19 december 2016) https://doi.org/10.22153/kej.2017.12.002 this research aims to study and improve the passivating specifications of rubber resistant to vibration. in this paper, seven different rubber recipes were prepared based on mixtures of natural rubber(nr) as an essential part in addition to , sbr, cr)with different rates. mechanical tests such as tensile strength, friction, resistance to compression, fatigue and creep testing in addition to the rheological test w copy (sem)test was used to examine the structure morphology of rubber. after studying and analyzing the results, we found that, recipe containing (brcis) of 40% from the natural rubber has the best mechanical and physical specifications to be used in applications that require the presence of rubber natural rubber, synthetic rubber, master batch. machinery and engineering equipment suffer from vibrations and noise problems. these problems increase dramatically when there is no means to prevent vibrations or it there are several to reduce the vibrations, control the natural , reduce wave vibration amplitude (through a method of effective system which include applying force with the same frequency and amplitude to the , but opposite phase direction and thereby the vibration force will be canceled in vibration sites ) or applying passive cheap and easily to manufactured, such as air springs , mineral springs , dampers and rubber mounts s a polymeric material which due to the flexible nature of the rubber compounds which enables it to dissipate energy used for the protection of engineering equipment , bridges, and buildings from the effect of vibrations[ are two types of rubber, natural and synthetic. natural rubber(nr) coming from latex is mostly polymerized isoprene with a small percentage of impurities in it. this will limit the range of properties available to it, although the addition of sulfur and vulcanization are used to improve the properties. synthetic rubber is any type of artificially made polymer material which acts as an elastomer. the use of synthetic and natural polymer blends is a common method improve the mechanical and physical properties of rubber composites[4,5,6]. m.h. almamoory effect of humidity on the mechanical and physical properties of natural rubber (smr 20) and synthetic rubbers (sbr 1502) and (brcis). the results shows that, the negative effect of humidit al-khwarizmi engineering journal properties of natural s. moosa*** this research aims to study and improve the passivating specifications of rubber resistant to vibration. in this paper, seven different rubber recipes were prepared based on mixtures of natural rubber(nr) as an essential part in addition to , sbr, cr)with different rates. mechanical tests such as tensile strength, hardness, rheological test were performed. copy (sem)test was used to examine the structure morphology of rubber. after (brcis) of 40% from the natural rubber has the best cations that require the presence of rubber, resistant to flexible nature of the rubber compounds which enables it to dissipate energy used for the protection of engineering equipment , bridges, and buildings from the effect of vibrations[4]. there are two types of rubber, natural and synthetic. natural rubber(nr) coming from latex is mostly polymerized isoprene with a small percentage of this will limit the range of properties available to it, although the addition of lfur and vulcanization are used to improve the properties. synthetic rubber is any type of artificially made polymer material which acts as the use of synthetic and natural blends is a common method improve the properties of rubber m.h. almamoory studied the effect of humidity on the mechanical and physical properties of natural rubber (smr 20) and synthetic rubbers (sbr 1502) and (brcis). the results shows that, the negative effect of humidity pdf created with pdffactory trial version www.pdffactory.com https://doi.org/10.22153/kej.2017.12.002 mailto:nabel.abdali@qu.edu.iq mailto:malia.m.f@mtu.edu.iq mailto:abbassahip@gmail.com https://doi.org/10.22153/kej.2017.12.002 http://www.pdffactory.com http://www.pdffactory.com nabel k. abd ali al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 2027 (2017) 21 on the properties of natural rubber is greater than its effects on the properties of synthetic rubbers[7]. almamoory prepared recipe used for engine mounts consist from50% nbr + 8% novolac + 20% sio2 +20% c, his results showed that the resilience decrease with increasing of novolac [8]. masomori designed a rubber magnetic dampers consist of (iir) rubber and ferrite powder with practical size (5-10) μm to reduce the noise and vibrations generated in the iron bridges associated with railway lines instead of traditional dampers[9]. ibrahim studied the effect of barium titanium ( batio3) on the mechanical properties of nbr rubber, they found that, the addition of ( batio3) as a filler lead to an increasing in the damping properties [10]. ahmed nemha prepared a new rubber composite materials(sbr with reclaim and novolac) for vehicles mountings, hemaintain that, hardness and wear resistance was enhanced with the presence of novolac[11]. v.s. chavan studied the analysis of anti vibration mounts for vibration isolation in diesel engine generator set. rubber and neoprene materials with and without several mount conditions are analyzed. the results shows that the neoprene material gives out the best vibration isolation and the dynamic stiffness is dependent on the frequency[12]. the major aim of this research is to study and examine the effect of rubber type on the mechanical behaviors of the seven selected rubbery blends for intivibration applacations and compare it with standard one that already used in aldewaniya tires factory. the testing results will be the main factor for detecting the best blend choice for the intivibration mounts applications. 2. experimental work the rubber compounds used in this study were prepared from natural rubber (smr-20) , styrenebutadiene rubber (sbr-1502),br cis, iir and cr rubber. carbon black (n330) filled recipes with other compounding materials such as filler; vulcanizing agent (sulfur) and accelerator were prepared with the compound formulations. the specification of the rubbers used in this work arelisted in table (1). in this work(seven) different recipes were prepared in the laboratory of aldewaniya tires factory according to their specifications. table (2) demonstrate the recipes content[13]. rubber processing technology consists of compounding (mixing), shaping, molding and vulcanizing. rubber is always compounded with additives: vulcanization chemicals, and usually fillers, anti degradants, oils or plasticizers. mixing and mastication are conveniently done using two roll mills (calender)the mixing operation was executed on two stages, as shown in table (3). the first one is called master batch. it consists of rubbersincludingactivators (zinc oxide), antioxidant(tmq), reinforcing agent carbon black(c.b) and process oil. at the end of the first stage, carbon black is blended with process oil in order to have optimum dispersion and coupling with rubber. the second stage is called the final batch. it consists of the previous master batch, curing agent (sulfur) and accelerators(cbs). these materials are added at the end of process to prevent pre-vulcanization which may occur due to the elevated temperatures as shown in table (3) . table 1, rubbers specification [13]. rubber sp.gr tg (oc) color hardness (shore a) resilience tensile strength, mpa, nr 0.934 72 red 20 100 excellent 17.23 25 sbr 0.94 55 yellow 40 85 good 22.0 26 cr 0.92 -43 yellow 20 – 95 good 18 -24 brcis 0.915 -56 white 20 40 excellent 23 27 iir 0.931 -73 yellow 40 -90 good 15 20 pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com nabel k. abd ali al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 2027 (2017) 22 table 2, recipes content[13]. material standard (pphr) stock1 (pphr) stock2 (pphr) stock3 (pphr) stock4 (pphr) stock5 (pphr) stock6 (pphr) stock7 (pphr) nr 100 95 80 60 40 70 sbr 1502 60 30 cr 5 brcis 40 30 iir 20 100 70 zinc oxide 5.5 5.5 5.5 5.5 5.5 5.5 5.5 5.5 (tmq) 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 wax 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 oil 5 5 5 5 5 5 5 5 c.b 48 48 48 48 48 48 48 48 (cbs) 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 sulphur 2.3 2.3 2.3 2.3 2.3 2.3 2.3 2.3 ctp.100 0.15 0.15 0.15 0.15 0.15 0.15 0.15 0.15 table 3, schedule of mixing cycles[13]. 3. laboratory tests all the tests(except creep and sem tests) were done in the labs of babylon tyres company. table (4) lists the test methods and the equipments used during the present work. table 4, equipments and standard test methods[13]. no test astm equipment 1 tensile test. d 412 monsanto t10 tensometer 2 compression set test, using calibrated spring loading, method a. d 395 b.s.903,pt.a.6 wallace compression set with constant (stress ) 3 hardness test. d 1415, d 2240 the wallace dead load hardness tester 4 rheological test. d 2084 monsanto rheometer odr e2000 5 dynamic fatigue test. d 430 wallace de mattia flexing machine 6 abrasion wear test d 5963 wallace machine 7 resilience test d 903 wallace machine 8 creep test d 2990 gunl machine item no. description stage (1) master batch 1 passing rubbers through rolls several times with decreasing a mill roll opening to 0.5cm. 2 during whole operation, cutting of milled rubber diagonally, rolled or spiraled, and passed into nip in horizontal and vertical state alternatively several times for homogenization. 3 banding with mill opening 2.5cm to 0.5cm for several times, and repeat item (2). 4 adding of stearic acid and zinc oxide. 5 adding of antidegredants, and repeat item (2). 6 adding half of each carbon black and process oil, and repeat item (2). 7 adding the other half of each carbon black and process oil, and repeat item (2). stage (2) final batch 8 cooling the master batch to the room temperature. 9 adding the accelerator. 10 adding the sulfur to the master batch. 11 sheeting the batch to a thickness of (0.5) cm. 12 cooling the batch to room temperature. pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com nabel k. abd ali al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 2027 (2017) 23 4. result and discussion table (5) show the results of tensile, hardness, compression set ,flexing (fatigue),resilience and wear resistance, while table (6) shows the results of rheological test. also the result of (sem) test demonstrate in figures( 1to 3). the best tensile strength is found with the stocks (2 and 3).this result may be due to the good compunction between nr and brcis blends at this percentage. also stocks 1,2,3, 6, and 7 have acceptable modulus and elongation at break. all the stocks(except stock 4) have a suitable hardness values. the higher hardness value of stock 4 can be attributed due to the fact that sbr is a copolymer of styrene and butadiene groups and for this reason acting as a harder block to increase the degree of the hardness of the sbr which increase the blend hardness[14]. the best compression set value and flexing or fatigue value is found with the stocks(2,3 and 7). also stocks (2,3 and 6) have the best results of wear resistance due to its minimum values of weighting losses. but the best result of resilience test found in stock 3. in the resilience test , the resulting value represent the amount of rebounded energy from the sample , so we can say that the stock 3 is the best for antivibration purposes due to the excellent damping properties. in addition to the mechanical properties we must be acquainted with the physical properties and cure specifications, the cure characteristics of the (seven) recipes are summarized in table (6). the scorch time ts2(period of time before vulcanization starts, its unit is minute. milli-minute) for stocks 3 and 5 are the best(longest value) in comparison with the periods of the other stocks. the curing time t90 for stocks (2, and 3) are also the best, where these periods are shorter than the other stocks. the curing time t90 for stocks (2, and 3) are also the best, where these periods are shorter than the other stocks. a long scorch period means high processing safety, and a short cure period is required to prevent over-cure. the values of the minimum torque ml, range from 3.66lb-in in stock (1) to 9.47lb-in in stock (4), and the values of the maximum torque, mh, range from 28.16lbin in stock (1) to 85.91lb-in in stocks (4). the torque difference between mh and ml,δm could be used as an indirect indication of the crosslink density and the stiffness of the rubber blend [15,16,17]. so, that is very logical in the value of stock 4 which have the higher value of δm. table 5, mechanical tests results. stock tensile strength (mpa) modulus at 200% (mpa) elongation at break (%) hardness shore a compression set % flexing (cycle) resilience % friction weight loss(gm) standard 18 2.6 500 40 8.8 54800 22 0.32 1 9.35 2.96 707 35 9.8 14300 24 0 .34 2 18.5 2.82 540 35 10.5 65800 23 0.22 3 21.9 2.5 650 42 12 83800 20 0.25 4 10.6 106 90 9 11200 39 0.0 5 11.7 1.14 408 33 20 10200 21 0.32 6 15 2.4 500 50 10 20700 26 0.14 7 11 2.81 400 40 8 60450 24 0.31 table 6, rheological test results. stock ts2 (m.m) t90 (m.m) ml (lb-in) mh (lb-in) m (lb-in) standard 1.1 2.17 3.50 28.16 24.66 1 1.04 2.13 3.66 29.63 25.76 2 0.96 1.73 4.12 38.62 34.5 3 1.0 9 2.11 4.69 31.41 26.72 4 0.83 2.17 9.47 85.91 76.44 5 1.10 2.31 5.35 32.14 26.79 6 0.97 2.43 5.10 32.93 27.83 7 1.08 2.15 3.80 32.93 29.13 creep test was performed to determine the viscoelastic behavior of the selected rubber stocks. so, in this work, the test wasn't to study the failure types because of the long duration to failure [18]. this test was carryout in the labs of material engineering college ,babylon university. pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com nabel k. abd ali al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 2027 (2017) 24 constant suitable load was applied and the deformation was recorded. the result of this test shows the minimum value of deformation occurs in stock 4 because the higher value of hardness due to the higher cross linking density[19]. so, the creep results are compatible with the pervious results. the result of this test demonstrate in table (7) below. table 7, creep test results. stock deformation after 1hr(mm) deformation after 2hr(mm) deformation after 3hr(mm) deformation after 4hr(mm) deformation after 5hr(mm) deformation after 6hr(mm) standard 1.12 1.15 1.20 1.40 1.40 1.40 1 1.85 1.87 1.95 2.22 2.22 2.22 2 1.15 1.18 1.21 1.40 1.40 1.40 3 1.33 1.35 1.42 1.50 1.50 1.51 4 0.2 0.21 0.23 .245 0.5 0.5 5 0.97 1.04 1.o45 1.15 1.20 1.21 6 1.05 1.08 1.01 1.20 1.30 1.30 7 1.11 1.14 1.19 1.22 1.31 1.31 the scanning electron microscopy (sem) was performed to examine the structure morphology of rubber[14]. this test was performed in the university of technology by using (te scan vega easy probe) device the result of selected stocks was illustrated in figures (1 to 3). this test indicated that the blends of stock 3 are very homogenous systems (i.e., separation between the blends compounds are not exist). the component of standard stock represent tow phase as shown in figure (3)while the structure of stock 2 represent the intermeddle case. relatively, that is a compatible with the experimental results. fig. 1. sem test for stock 2. fig. 2. sem test for stock 3. pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com nabel k. abd ali al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 2027 (2017) 25 fig. 3. sem test for standard stock. 5. conclusions from this work , may be made the following conclusions: 1. mechanical properties of ( nr) is improved when it blended with the other rubbers and improvement in mechanical properties has advantages and disadvantages according to the engineering uses. 2. the mechanical properties such as tensile strength, elongation at break, compression set and hardness properties were strongly dependent on the blend structures, that is very clear with (sem) test for the three selected samples. 3. rheological test has a compatible result with the mechanical tests ,that is very understandable in the value of(δm), higher value of(δm) lead to the higher cross linking value. 4. blend recipe which contains 40pphr (brcis) with60pphr( nr) has the optimum properties which can be use in antivibration applications due to the excellent resilience properties for this types of rubber. 5. blends contains40pphr (nr) with 60pphr(sbr) has the maximum value of hardness because the ability of (sbr) to achieve a high cross linking densities due to the its nature. 6. according to experimental results, for antivibration purposes , using of ( nr with sbr) blends is unbeneficial because the poor damping properties due to the high stiffness. this blends can be use in the applications that required higher stiffness and lower resilience. 6. references [1] w. d. callister, “material science and engineering” 5th edition, john wiley and son, new york, 2000, pp. 45-46 usa. [2] mroczkowski, t., s., "to pirelli armstrong" , u. s. patent 063 2684, july 16, 2000. [3] mary c. boyce , “mechanical behavior of particle filled elastomers", rubber chem. technol., vol. 72, pp. 633–656, may 1999. [4] t. aj and j. kp, "blends of natural rubber, novel techniques for blending with specialty polymers", london: chapman & hall, 1998. [5] j. white, s. k. de and k. naskar, "rubber technologist’s handbook volume 2", rapra technology, united kingdom ,2009. [6] j. g. drobny, " handbook of thermoplastic elastomers", czech republic may , 2007. [7] m.h. almamoory, "effect of humidity on the properties of (sbr 1502) and (brcis)",journal of babylon university , engineering sciences,vol. 8,no.3, july, 1999. [8] m.h. almamoory, "mechanical & physical properties of rubber composite for engine mounting ",university of technology, doctorate dissertation, 2003. [9] masamori, h. "development of magnetic rubber damper with a constraining layer " railway technology avalanche , no.8,march 1, 2005. [10] m. ibrahim, "effect of batio3 on the mechanical properties of nitrile-butadiene rubber vulcanizate" egypt. j. solids, vol.29, no.1, 2006. [11] ahmed nemha, "preparation of polymeric composite materials for frictional wear resistance purposes ",university of babylon, master thesis, 2009. [12] r. askhedkar, s. b. sanap, "analysis of anti vibration mounts for vibration isolation in diesel engine generator set pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com nabel k. abd ali al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 2027 (2017) 26 "international journal of engineering research and applications, vol. 3, , pp.14231428, 2013. [13] manuals of dunlop row materials specification file no.3-3,1981. [14] rania mouner, "properties of rubber blends based on natural rubber loaded with different fillers and cured by gamma radiation”master thesis,ain shams university, 2005. [15] klaus friedrich, stoykofakirov and zhong zhang, "polymer composites from nano-to macro-scale", springer science and business media inc., 2005. [16] g. v. jovanović, suzana s. jovanović and jaroslavasimendić, "the effect of gamma radiation on the ageing of sulfur chemical industry and chemical engineering quarterly, serbia,15 (4) 291−298, 2009. [17] nabel kadum, "the effect of carbon black on the mechanical properties of sidewall tyre rubber ",doctorate dissertation, university of technology, 2013. [18] henrik and peter" strength and creep analysis of glued rubber foil timber joints " lund, sweden, december, 2005. [19] mohsinnoorihamzah ,"effect of carbon blank type on the mechanical behavior of elastomeric material ",al-qadisiya journal for engineering sciences ,vol. 6.no 3 ,2013. pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com )2017( 20-27، صفحة 2، العدد13دجلة الخوارزمي الھندسیة المجلم نبیل كاظم عبد علي 27 تحسین المواصفات المیكانیكیة واالنسیابیة للمطاط الطبیعي المستخدم في تطبیقات مقاومة االھتزاز ***صاحب موسىعباس **مالیة محمد فرحان* علي عبد نبیل كاظم جامعة القادسیة / قسم ھندسة المواد * بغداد -الكلیة التقنیة/ قسم ھندسة تقنیات المواد***،** nabel.abdali@qu.edu.iq :البرید االلكتروني* malia.m.f@mtu.edu.iq :البرید االلكتروني** abbassahip@gmail.com :البرید االلكتروني*** الخالصة عجن�ات مطاطی��ة مختلف��ة باالعتم��اد عل��ى )س��بع(ت��م تحض��یر . وتحس��ینھا ھ��ذا البح��ث إل��ى دراس�ة المواص��فات التخمیدی��ة للمط��اط المق��اوم لالھت�زازیھ�دف ً أساسی اً جزءبوصفھ من المطاط الطبیعي عجنات تم إجراء االختب�ارات المیكانیكی�ة . وبنسب مختلفة )(iir, brcis, sbr,crالمطاط الصناعي فضال عن ا إج��راء فح��ص االنس��یاب لمع��رف الخ��واص إض��افة إل��ىمث��ل اختب��ار الش��د والص��الدة واالحتك��اك ومقاوم��ة االنض��غاط والتص��ادم وفح��ص الك��الل و الزح��ف وتحلیلھ�ا وبع�د دراس�ة النت�ائج . سة ش�كل الت�رابط ب�ین الخالئ�ط المختلف�ةلدرا (sem ) ـال أیضا إجراء فحصتم و. للعجنات المحضرة الفیزیاویةالمیكانیكیة و الت�ي تمتل�ك أفض�ل مواص�فات میكانیكی�ة وفیزیاوی�ة لك�ي الطبیع�ي ھ�يم�ن المط�اط % 40بنس�بة ) (brcisالعجنة التي تحتوي عل�ى المط�اط الص�ناعي أنوجد .لالھتزازتستعمل في التطبیقات التي تتطلب وجود مطاط مقاوم pdf created with pdffactory trial version www.pdffactory.com mailto:nabel.abdali@qu.edu.iq mailto:malia.m.f@mtu.edu.iq mailto:abbassahip@gmail.com http://www.pdffactory.com http://www.pdffactory.com (microsoft word 138-148\307\315\343\317 \346\344\346\321\307 \332\346\335) design an integral sliding mode controller for ahmed khalaf hamoudi *,**department of control and systems engineering *email: (received https://doi.org/10.22153/kej.2017.09.003 abstract the goal of this paper is to design a robust controller for controlling a pendulum system. the control of nonlinear systems is a common problem the sliding mode controller (smc) is the best solution for controlling a nonlinear system. the classical from two phases. the first phase is the reaching phase and the second is the sl chattering phenomenon which is considered as a severe problem and undesirable property. it is a zigzag motion along the switching surface. in this paper, the chattering spite of smc is a good method for controlling a nonlinear system but considered as undesired property. the integral sliding mode controller (ismc) also, the ismc is a good method for controlling a nonl be considered as an effective and powerful technique. in ismc method, the reaching phaseis eliminated which considered a main part in designing classical s mode controller (csmc),is the ability to make the systems asymptotically stable. the pendulum system testing the csmc and ismc. the results obtained comparied with the csmc. finally, matlab keywords: chattering phenomenon, classical sliding mode controller, integral sliding mode controller, swi surface. 1. introduction in last two decades, the methods for controlling nonlinear systems take a much interest from many researchers and as a result many methods were developed [1]. one of them is the sliding mode control system (smc) which is consider as an effective and robust control method that is used successfully in wide variety of systems. the most important property in using smc is the ability of this controller to make the system insensitive to external disturb parameters uncertainty [2]. in spite of the smc robustness and its better performance, sever from the problem of ''chattering phenomenon '', which is considered as drawback property. to reduce this chattering phenomenon in the smc, many methods were developed al-khwarizmi engineering journal,vol. 13, no. 1, p.p. 1 design an integral sliding mode controller for a nonlinear ahmed khalaf hamoudi* noora off abdul rahman *department of control and systems engineering/ university of technology *email: ahmed_khk22@yahoo.com **email: rb_6_1981@yahoo.com received 29 may 2016; accepted 19 september 2016) https://doi.org/10.22153/kej.2017.09.003 the goal of this paper is to design a robust controller for controlling a pendulum system. the control of nonlinear systems is a common problem that is facing the researchers in control systems design. ontroller (smc) is the best solution for controlling a nonlinear system. the classical from two phases. the first phase is the reaching phase and the second is the sliding phase. the smc suffers from the chattering phenomenon which is considered as a severe problem and undesirable property. it is a zigzag motion along the switching surface. in this paper, the chattering is reduced by using a saturation function instead spite of smc is a good method for controlling a nonlinear system but it still suffers from long settling time desired property. the integral sliding mode controller (ismc) can be used to reduce the ismc is a good method for controlling a nonlinear systems. ismc is simple, has a high performance and can be considered as an effective and powerful technique. in ismc method, the reaching phaseis eliminated which signing classical smc. the important property of the ismc as well as the ability to make the systems asymptotically stable. the pendulum system testing the csmc and ismc. the results obtained from the simulation showed the advantages of using the ismc when matlab software package was adopted in this paper. classical sliding mode controller, integral sliding mode controller, swi the methods for controlling nonlinear systems take a much interest from many researchers and as a result many [1]. one of them is the sliding mode control system (smc) which is an effective and robust control method used successfully in wide variety of the most important property in using smc is the ability of this controller to make the external disturbance and in spite of the smc e, but it is from the problem of ''chattering phenomenon '', which is considered as drawback chattering phenomenon were developed to overcome this problem. one of them is by using a boundary layer instead of signmum nonlinear part of controller [2]. proposed to use a fuzzy logic system sliding mode controller to get a new structure called sliding mode fuzzy controller [ other hands, some researchers the chattering by using a genetic algorithm [ recently some researches, proposed to use the particle swarm optimization technique i reduce the drawbacks of the chattering phenomenon [5]. the advantage smc is the reduction in order original system equation [6]. the designed control law in smc can drive the system state towards the manifold surface and stay surface for all future time until re origin. churn and we was first introduced the khwarizmi engineering journal,vol. 13, no. 1, p.p. 138147 (2017) onlinear system rahman** the goal of this paper is to design a robust controller for controlling a pendulum facing the researchers in control systems design. ontroller (smc) is the best solution for controlling a nonlinear system. the classical smc consists iding phase. the smc suffers from the chattering phenomenon which is considered as a severe problem and undesirable property. it is a zigzag motion along s reduced by using a saturation function instead of sign function. in still suffers from long settling time which is can be used to reduce the settling time. high performance and can be considered as an effective and powerful technique. in ismc method, the reaching phaseis eliminated which as well as the classical sliding ability to make the systems asymptotically stable. the pendulum system was used for ed the advantages of using the ismc when classical sliding mode controller, integral sliding mode controller, switching . one of them is by using a signmum function in ]. other researchers logic system with a sliding mode controller to get a new structure called sliding mode fuzzy controller [3]. on the suggest to reduce the chattering by using a genetic algorithm [4]. recently some researches, proposed to use the technique in order to reduce the drawbacks of the chattering advantage of using the by one from the ]. the designed control law in smc can drive the system state trajectory towards the manifold surface and stay in this for all future time until reaching the was first introduced the al-khwarizmi engineering journal ahmed khalaf hamoudi al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 138147(2017) 139 integral sliding mode (ismc) [7], which is similar to the smc since it is insensitive to external disturbance and parameters uncertainty [8]. the control law in the ismc consists from two major parts, the first part is the nominal control which is responsible for the performance of the nominal system and the second part is the discontinuous control that is used to reject the external disturbance and parameters uncertainty [8]. in this paper the performance of pendulum system will be improved by using the ismc and the results show high validity when using the proposed controller. 2. classical sliding mode controller (smc) in modern control systems, the smc is a common method for designing a robust controller technique. this controller was extremely used with nonlinear system since 1950, and it is extended to use with large various types of applications such as electrical servo drives, pendulum, etv and others. the differential equation that is used to govern the sliding mode control has order less by one than the order of original system. the main drawback of the smc is the ''chattering'' which is phenomenon of oscillations having a finite frequency and amplitude along the sliding surface. the problem of chattering phenomenon can be solved by using many methods as mentioned above in section 1. sliding mode controller consists of two major phases [6]: a: reaching phase: in this phase the state trajectories are oriented toward the switching surface s=0; hence, the sliding phase will be started at this instant as shown in figure (1). b: sliding phase: in this phase the state trajectory is enforced to stay on the switching surface and to move along this surface until reaching the origin in finite time as shown in figure (1). fig. 1. the two phases of the sliding control [2]. fig. 2. the shape of sliding surface [2]. the control law is defined as: � � ���� ��� … �1 where, ��� is the equivalent control part which required to oriented the system state trajectory toward switching surface (� � 0) and ��� is the discontinuous control part to enforce the state trajectory to move along the switching surface towards the origin. the control ��� is defined as below [10]: ��� � ���� ������ … �2 where, k is a constant with positive value. fig. 3. the shape of a signum function. by substituting equation (2) in (1), the control law can be rewritten as: � � ��� � ��� ������ … �3 the sliding surface characterized as: � � �� � �� ; � � 0 … �4 where, λ is a constant parameter with a positive value. let the error and its derivatives defined as: �� � � � � ! and �"= �� � � where ! is the final position that can be considered as the desired position. then, equation (4) will be rewritten as below: � � λ�� � �" … �5 for � � 1, equation (5) will be as: � � �� � �" the derivative of the sliding variable �� = ���+ ��" … �6 ahmed khalaf hamoudi al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 138147(2017) 140 the main goal is to keep the ���, ' close to switching surface in phase plane. the general form of motion equation for any nonlinear system: �� = (�� � )�x � � +�x, t … �7 to satisfy the condition �� � 0 that the right side of equation (6) equal zero by selecting the discontinuous gain ��� as follows [6]: 0, )( ),( )( >             ∂ ∂ ∂ ∂ += ko xb txd x so x so koxk n … (8) in above control equation (3), the ������ function caused a chattering phenomenon. this chattering phenomenon is undesirable property appearing along the sliding surface, the major reason that caused this phenomenon is the ''���� function'' that is present in control equation (3). the classical smc is suffering from the chattering which is considered as a severe problem in smc. the boundary layer function can be using to reduce the chattering. the �.' �� function is used instead of ���� �� function in control law. the �.' �� function that shown in figure (4) can be described as below [6]:      <− <<− >+ = )0/(1 )1/1(/ )0/(1 )/.( ϕ ϕϕ ϕ ϕ s ss s ssat … (9) fig. 4. the /01 �/ function [2]. the ������ function in equation (3) is replaced by �.' �� function and the control law can be written as below: � � ��� � ��� �.' … �10 3. integral sliding mode controller (ismc) integral sliding mode control (ismc) is a nonlinear robust controller, designed for controlling nonlinear systems [1]. the goal of the proposed ismc is to eliminate the reaching phase by enforcing the state trajectory, which starts from any initial state, to be in sliding phase throughout the entire plant trajectory and to slide along the switching surface until reaching the origin. the difference between the ismc approach and the classical sliding mode is that the order of motion equation in the ismc is the same as the order of the original system, while in the classical sliding mode; the order is less by one from the original system [9]. the robustness of the system in the ismc is guaranteed because in final trajectory the error and its derivatives reach zero value. also in ismc the system is insensitive to variations of system parameter and external disturbance. the main problem in this controller, as well as in classical smc, is the chattering phenomenon in the control action; and to reduce this chattering may use some functions such as saturation, dead zone and inverse of tan instead of sign function which is usually used in classical sliding mode. the complete system with the ismc is shown in the following figure: fig. 5. the closed loop control system using ismc. the procedure of designing the ismc with any nonlinear system can be described as below: ��� � �2 � 3 ; 3�0 � ��2�0 … �11 the ��� is sliding surface, 3 is the integral term and �2 defined as in classical sliding mode control as described in equation (5). the integral term 3�0 is determined based on the initial condition �2�0 . the integral term z will be selected in order that the sliding variable ��� has a zero value and this make the system dynamic in the sliding mode from the initial instant of time. the derivative of the sliding variable ��� is given as: �� � 4 5 46 �� � 3� … �12 the second step is to describe the control law of the ismc as: � � �7 � ��� … �13 the nominal part of controller �7 is used to maintain the nominal system dynamics with reference characteristics, where ��� is the second ahmed khalaf hamoudi al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 138147(2017) 141 part of the controller that is used to reject the external disturbance and parameters uncertainty as in [9] and by substuting equation (7) in equation (12) ���4 5 46 8(�� � )�� �7�)�� ��� �+��, ' ] +3� … (14) where the discontinuous controller is defined as ��� � ���� ������ … �15 where, ��� is the same as presented in equation (8) with positive value. therefore, equation (12) will be as bellow: � � �7 � ��� ������ to satisfy the rejection of the external disturbance and variation of system parameters, the integral term is assumed to be as: 3��� 4:5 46 8(�� � )�� �7] … �16 by substituting the equation (16) in (14), we will get the equation as: ���4:5 46 8)�� ��� � +��, ' ] … �17 in the design of the ismc, the sliding surface and control will be described as: ��� � �2 � 3 ; z�0 � ��<�0 ���� � ��2 � 3� ; � � �7 � ��� ������ … �18 finally, when using the boundary layer, the equation of control law (18) rewritten as below: � � �7 � ��� �.' … �19 4. plant description consider a second order of the pendulum system described by equation: ? � �. sin � c � � def � +�' g … �20 where: the angular position of the rod with vertical axis and it is measure in (radian) and it consider as the controlled variable (output), � the angular velocity and it is measure in (radian/ second), t the torque applied at the end of the pendulum and it measure in (newton. meter) and it is considering as the control input. and d(t) is the external disturbance applied to the system. a common problem in real plant is the presence of an external disturbance and parameters uncertainty. the nominal value of parameter a=10, b=1 and c=10, the uncertainties values of above parameters are h. � 0, hc � ∓0.5, hd � ∓5. table 1, the maximum and minimum pendulum parameters values) parameter value minimal value maximal value a 10 10 b 0.5 1.5 c 5 15 fig. 6. the simple pendulum [4]. the error of the pendulum system can be described in the state equation as: let the error �� = � ! and �"k � where, ! is the desired position which is the equilibrium point. equation above can be rewritten as: ��� = ��" … �21 ��" � �. ∗ sin where, . � h. ∓ .7, c � hc ∓ c7, d � hd ∓ .d7 �� = ��� + ��" … �23 by substituting equation (21), (22) and (2) in equation (23), ��� � �2 � case (a): design the classical sliding mode controller (csmc) for pendulum system the design of csmc controller is written as in equation (3): � � 1 c 8. sine�� � !g � c�" ] � ��� ������ … �25 when the boundary layer is used, the control law rewritten as described in equation �10 : � � 1 d 8. ���e�� � !g � c�"] � ��� ������ … �26 ahmed khalaf hamoudi al-khwarizmi engineering journal, vol. 13, no. 1, p.p. case (b): design the integral sliding mode controller (ismc) for pendulum system the sliding variable is written according to equation (18) as: ��� � �2 � 3 ; 3�0 � ��2�0 and �2 � �� � �" and the error equation for the pendulum system was described as: �? � �d�� � d"�� , d� , d" � 0 the values d� and d" are assigned depending on the required characteristics of plant dynamics. in ismc design, the derivative of integral term is described as below: 3��d� ∗ � � d" ∗ � � � �" the nominal control is described as: finally, the control law is written according to equation (18) as: when the boundary layer is used, the above equation will be rewritten as: 5. the simulation results case (a): the classical sliding controller (csmc) with a /\]^ function fig. 7. the error _`vs. time of the c khwarizmi engineering journal, vol. 13, no. 1, p.p. 142 sliding mode system the sliding variable is written according to … �27 … �28 and the error equation for the pendulum system … �29 assigned depending on dynamics. design, the derivative of integral term is ... �30 �7 � 1 d 8. ���e�� � ө!g � c�" � d�� � d"� ]� finally, the control law is written according to � � 1 d 8. ���e�� � ө!g � c�" � d�� � d � ��� ������ used, the above � � 1 d 8. ���e�� � ө!g � c�" � d�� � d" � ��� �.' liding mode function csmc. fig. 8. the derivative error x csmc. fig. 9. the control action u vs. time of the fig. 10. the sliding variable s classical smc . khwarizmi engineering journal, vol. 13, no. 1, p.p. 138147(2017) … �31 d"��] … �32 "��] … �33 2x vs. time of the vs. time of the csmc. s vs. time of the ahmed khalaf hamoudi al-khwarizmi engineering journal, vol. 13, no. 1, p.p. fig. 11. the plot of the phase plane between _b of the classical smc. case (b): the classical sliding mode controller (csmc) with boundary layer fig. 12. the error _` vs. time of the csmc fig. 13. the derivative error _b vs. time of the csmc. khwarizmi engineering journal, vol. 13, no. 1, p.p. 143 the plot of the phase plane between _` and lassical sliding mode with boundary layer vs. time of the csmc. vs. time of the fig. 14. the control action c vs. time of the csmc. fig. 15. the plot of sliding variable s vs. time of the csmc. fig. 16. the plot of phase plane between the error _` and the derivative error _b of the csmc. khwarizmi engineering journal, vol. 13, no. 1, p.p. 138147(2017) vs. time of the csmc. . the plot of sliding variable s vs. time of the . the plot of phase plane between the error of the csmc. ahmed khalaf hamoudi al-khwarizmi engineering journal, vol. 13, no. 1, p.p. case (c): the integral sliding controller with a /\]^ function fig. 17. the error d` vs. time of the ismc. fig. 18. the derivative error _bvs. time of ismc. fig. 19. the control action c vs. time of the ismc. khwarizmi engineering journal, vol. 13, no. 1, p.p. 144 liding mode vs. time of the ismc. vs. time of the vs. time of the ismc. fig. 20. the plot of sliding variable s vs. time of the ismc. fig. 21. the plot of phase plane between the error _` and the derivative error _b of the ismc. fig. 22. the plot of the sliding variable s and the integral term e vs. time of the ismc khwarizmi engineering journal, vol. 13, no. 1, p.p. 138147(2017) the plot of sliding variable s vs. time of the the plot of phase plane between the error of the ismc. the plot of the sliding variable s and the vs. time of the ismc ahmed khalaf hamoudi al-khwarizmi engineering journal, vol. 13, no. 1, p.p. case (d): the integral sliding mode controller with boundary layer fig. 23. the error _` vs. time of the ismc. fig. 24. the derivative error _b vs. time ismc. fig. 25. the control action c vs. time of the ismc. khwarizmi engineering journal, vol. 13, no. 1, p.p. 145 ntegral sliding mode vs. time of the ismc. vs. time of the of the ismc. fig. 26. the sliding variable f vs. time of the ismc. fig. 27. the plot of phase plane between the error _` and the derivative error _b of the ismc. fig. 28. the plot of the sliding variable integral term g vs. time of the ismc. khwarizmi engineering journal, vol. 13, no. 1, p.p. 138147(2017) vs. time of the ismc. the plot of phase plane between the error of the ismc. the plot of the sliding variable f and the vs. time of the ismc. ahmed khalaf hamoudi al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 138147(2017) 146 6. discussion in this work, smc and ismc have been considered for controlling the position of the pendulum system. the results of smc and ismc have been included in this work to show the proprties of each controllers with the presence of the external disturbance and paramrters uncertinty. each of the above controllers has the ablility to make the system asymptotically stable under the effect of external disturbance and the parameters uncertainty by making the error and the derivative of error equal to zero value as shown in figures (7), (8), (17) and (18). both the smc and ismc are suffering from the chattering problem because of the effect of ������ function as shown clearly in figures (9) and (19), this problem is solved by using the boundary layer as shown in figures (14) and (16). when using the ������ function, the state trajectory in the csmc hits the switching surface vertically as shown in figures (11) and (9), and this caused a chattering phenomenun, while in using the boundary layer the state trajectory hits the sliding surface in arc shape as shown in figures (16) and (14). the same thing was apear clearly when using the ismc as shown in figures (21), (19), (27) and (25). the results show that the effect of the external disturbance and the parameters uncertainty of the dynamic system is cancelled by using the ismc as shown in figures (25) and (27). in figure (27), the error (��) and the dervitive of error ��" reaches the origin in final trajectory, which means that its values equal to zero. 7. conclusion the most important improvement of using ismc is the reducing of the settling time response of system comparing with the csmc as shown in figures (12) and (23). in the csmc the settling time is 6.5 sec as shown in figure (12), where in the ismc the settling time is reduced to 0.8 sec as shown in figure (23). the ismc consists of two parts, the first part is nominal control that is used to control the nominal system dynamics while the second part is the discontinous control which is used to reject the pertubaration term (the perterbation term consists of the external disturbance and parameters uncertainty).in using the ismc, the pendulum system is is preseented by the nominal model from the from thr first instsnt . this nominal model is not effected by the perturbation term. the results shows that the csmc and ismc can be considered as a rubust controller, since it can give a good response even with the presence of disturbance and parameters uncertainty as shown in figures (14) and (25). from figures (11), (16), (21) and (27), it is seen clearly that the csmc and ismc are able to make the system asymptotically stable. 8. references [1] c. a. yfoulis, a. muir, and p. e. wellstead, “a new approach for estimating controllable and recoverable regions for systems with state and control constraints,” international journal of robust and nonlinear control, vol. 12, no. 7, pp. 561-589, 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[7] t. l. chern and y. c. wu, “design of integral variable structure controller and application to electrohydraulic velocity servo systems”, vol. 138, no. 5, pp. 439-444, 1991. [8] s. mondal and c. mahanta, “adaptive integral higher order sliding mode controller for uncertain systems,” journal of controltheory and applications, vol. 11, no. 1, pp. 61-68, 2013. 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p)� (jxأu-رة ا$`(p و,p0g" أ( 2+^ ا8$ �ول d ا�0`�ام3e ھ=ا ا: ;<7$� 3e . ا$8 *() ذو ا$ (r ا5q45!3 ا3b,-/0$ ا!^ ) ts( ا$a اp0�5)ار ا1x1$ل�icه وh$=i أ70h-ر ا$8 *()ات ,�#1," ا7$ �ا$b9<0 8$ا sj-0" ا$8 *()ات أظ@)ت "*$-+e ا(*hام "وأ� .b$sj-04>19ل abc "اi:-8$ب $s,-4(z .,(7b:� ا�0` effect of journal misalignment on the static characteristics of porous journal bearings lubricated with couple stress fluid 1 al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 8, no. 2, pp 42 53 (2012) effect of journal misalignment on the static characteristics of porous journal bearings lubricated with couple stress fluid lekaa' h. abd al-shaheed department of mechanical engineering /babylon university email: lekaa_hameed@yahoo.com (received 25 april 2011; accepted 4 march 2012) abstract in this paper, a theoretical study to the effect of journal misalignment on the static characteristics of oil filled porous journal bearing when lubricated with couple stress fluid has been carried out. the analytical model used through this work is for a bearing with isotropic permeability. considering isotropic permeability the reynolds' equation for the oil film is modified to include a so – called filter term and the effect of fluid coupled stress. the pressure equation for the porous medium is obtained from darcy's law and continuity equation. the equation which was used to evaluate the oil film thickness was modified to include the effect of possible misalignment in longitudinal and transverse directions. the governing equations with appropriate boundary conditions are numerically solved using a suitable numerical technique. a computer program has been prepared to solve the governing equations. the validity of the program has been tested by comparing the results obtained through this work with that published in available works. the comparison shows a good agreement between the results obtained through this work and that published by other workers. by comparing the behavior of aligned and misaligned bearing it was found that the journal center misalignment has a considerable effect on the performance parameters of the bearing which can not be neglected. key words: static characteristics, self lubricated bearing, misaligned bearing, uniform permeability, coupled stress. 1. introduction in most theoretical investigations of hydrodynamic lubrication it has been assumed that the journal and the bearing axis are aligned. this is an unrealistic assumption for the bearing operating with small film thickness since the bearings often operate in misaligned condition. bearing misalignment can vary in magnitude and direction. the most important cases to be considered are vertical , twisting , and horizontal misalignment or combination of these can also occur. most investigators in this area confined their work to solid bearing. a little work has been found related to the behaviour of aligned porous bearing lubricated with coupled stress fluid, while most works found related to study the behaviour of porous bearing lubricated with newtonian – lubricant as can be seen in references [1 – 8]. it was found that the newtonian fluid constitutive approximation is not satisfactory engineering approach to many lubrication problems. hence the effects of non – newtonian behaviour must be taken into account in the realistic study of these bearings. many micro continuum theories have been developed to describe the behaviour of non – newtonian fluids. airman et. al. [9,10] developed a micro continuum theory to describe the behaviour of fluids containing structure such as polymer. naduvinamani et. al. [11] used the couple stress theory to analyze the squeeze film lubrication of a short porous bearing. a main conclusion through this work is that under cyclic load the couple stress fluid provide a reduction in journal velocity and an increase in minimum permissible height of squeeze. the surface roughness effect in a short porous journal bearing lubricated with a couple stress fluid was studied by naduvinamani et. al. [12]. it was mailto:lekaa_hameed@yahoo.com lekaa' h. abd al-shaheed al-khwarizmi engineering journal, vol. 8, no. 2, pp 42 -53 (2012) 43 observed during this work that the effect of surface roughness on the bearing characteristics are more pronounced for couple stress fluids as compared with newtonian fluids. using the couple stress theory to investigate the lubrication mechanism of synovial joints was carried out by bujurke and ramesh [13]. they showed that the effects of surface roughness are considerably prounced for poroelastic bearings with couple stress fluid as lubricant compared to classical case. recently the flow and heat transfer of couple stress fluid in a porous channel with expanding and contracting walls have been investigated by srinivasacharya and srinivasecharyulu [14]. graphs for velocity components and temperature distribution are presented for different values of the fluid and geometric parameters. naduvinamani and patil [15] used a numerical solution to the finite modified reynolds' equation for couple stress squeeze film lubrication of porous journal bearing. they concluded that under a cyclic load, the effect of couple stress is to reduce the velocity of the journal center and to increase the minimum permissible height of the squeeze film. so far it seems that all the above researches ignore the effect of journal center misalignment. the effect of bearing misalignment on the bearing characteristics such as the mean load carrying capacity, mean frictional force, and the other bearing characteristics are investigated during this work. 2. numerical analysis 2.1. model of the misaligned porous journal bearing the model of misaligned porous journal bearing lubricated with couple stress fluid shown in figure (1) is adopted through the present work. fig. 1. geometrical configuration of the misaligned porous journal bearing. 2.2. governing equations the governing equation for the pressure distribution in the oil – film is given by the modified reynolds' equation including a so – called filter term and coupled stress effect. for a journal bearing lubricated with coupled stress fluid with a constant viscosity the modified reynolds' equation can be written as [12]: …(1) where:   equation (1) can be written in dimensionless form as follows: …(2) where: [15] …(3) …(4) x h u z pk hg zx pk hg x                                                6 )1( 12 ),( )1( 12 ),(                                              ^ ^ ^ ^^^ ^2 ^ ^^^ 6 )1( 12 ),( 4 1 )1( 12 ),( h z p lhg za x p lhg c c          ^ ^ ^^^^^^^ 2 tanh2412),( 323 c ccc l h lhlhlhg k          2 z,  top view y,  l 1 z,  front view y,  x, j b=0 solid housing porous bearing ro ri   side view lekaa' h. abd al-shaheed al-khwarizmi engineering journal, vol. 8, no. 2, pp 42 53 (2012) 44 where  represents the ratio of microstructure size to the porous size. for a vary small , i.e. <<1, the polar additives percolate into the porous matrix. it in clear that when  0, the flow become newtonian flow. it can be shown that the couple stress parameter (lc) has a units of length and it may be regarded as chain length of polar additives and can be evaluated as [15,16]: cl …(5) the fluid film thickness in cooperating the effect of journal misalignment in both directions (axial and twisting) can be expressed in non – dimensional form as follows [17]:  sincoscos1 21 ^ h …(6) where: 11 tan2               d l c ri …(7) …(8) the two independent misalignment angles (1 and 2 ) are measured from =0; it is clear from equation (6) that the oil gap geometry depends on ( and  ). due to the continuity of the fluid motion at the porous matrix, the oil pressure inside the porous matrix satisfies the laplace equation which can be expressed as [12, 15] 0.0 2 *2 2 *2 2 *2          z p y p x p …(9) the classical reynolds' boundary conditions are adopted through this work. the reynolds' conditions can be expressed as [ 1,18];                                c so at p p prp ratzrpzp zrpzp rprppp      0 )2/1,,( 1)(),,(),( 0),0,(),0( 0)1,,()0,,()1,()0,( ^ ^^ …(10) where c is the angle at which cavitations starts. 2.3. bearing parameters after evaluating the pressure field through the oil film, the bearing performance parameters can be calculated as follows: the radial and tangential components of the load are found as :                                     ddpw ddpw c c t r 1 0 0 ^ ^ 1 0 0 ^ ^ sin, cos, 1 …(11) the total bearing load carrying capacity can be expressed in dimensionless form as; 2 ^ 2 ^^                   tr www …(12) the attitude angle can be found as:    ^^1tan rt ww …(13) the friction force can be expressed in dimensionless form as [16] ; ^ 1 0 0 ^^ ^ ^ 2 1 dzd ph h f c h                  …(14) the coefficient of friction can be evaluated as: ^ ^ f(r/c) w fh  …(15) the oil side leakage flow for the porous journal bearing can be evaluated as [ 16]; …(16) 2.4. method of solution the pressure distribution in the oil film can be obtained by solving the modified reynolds' equation (1), the laplace equation (9) coupled with the modified oil film thickness equation (6) with the reynolds' boundary conditions equation ^ ^ ^ ^ ^^^ ^^^^^ ^ 1z 1 0 0 ^ ^ ^ 2 cosh 2 2 cosh 12 * z 2222 ^ dyd l h l hhy lhyhy h p q c c c s c                                                            22 tan2               d l c ri lekaa' h. abd al-shaheed al-khwarizmi engineering journal, vol. 8, no. 2, pp 42 53 (2012) 45 (10) simultaneously using iterative numerical scheme. the field of solution is divided into grid spacing (n1=8, n2=180, n3=12); each has a mesh size r ^ * θ *z ^ for porous matrix and grid spacing (n2=180, n3=12); each has a mesh size θ *z ^ for oil film thickness. gauss siedel iterative scheme with successive under relaxation has been used to solve the governing equation of the problem. the iterations are stooped when the following convergence criteria are satisfied. for the oil pressure inside the porous matrix the convergence criterion can be expressed as:                       5 ^ ,, ^ ,, 1^ ,, 10 * ** n kji n kji n kji p pp …(17) while for the oil pressure in the bearing oil film the convergence criterion can be expressed as:                       5 ^ , ^ , ^ , 10 1 n nn kj kjkj p pp ...(18) a computer program written in fprtran – 90 language has been used to solve the governing equations of the problem. figure (2) shows the flow chart of the computer program used during this work. 4 assume =0.05 2 start read l,c,ri,ro,nj,k1,µ, 1 , 2,lc ,ps if error <10-5 no x=x+1 if x<1000 no 2 yes calculate *^ ,, kjip for porous bearing matrix using the finite difference of the darcy's equation yes calculate the error from equation ( 17 ) 1 3 2 =+0.05 will be continue yes if error <10-5 no x=x+1 if x<1000 no 3 yes 2 =+0.05 calculate ^ ,kj p oil film calculate the error from equation ( 18 ) lekaa' h. abd al-shaheed al-khwarizmi engineering journal, vol. 8, no. 2, pp 42 53 (2012) 46 fig. 2.flow chart of the computer program. 3. results and discussion the combined effect of couple stress and journal center misalignment on the performance of porous journal bearing is predicted through this work. the effect of couple stress is taken into consideration on the basis of stokes couple stress fluid model for lubricant. a finite porous journal bearing operated under steady conditions is analyzed. all bearing characteristics such as the load carrying capacity (w), frictional coefficient f(r/c) , friction force, the lubricant side leakage and the attitude angle are functions of the couple stress parameter (lc) and the eccentricity ratio (). the computer program prepared to solve the governing equations of the present work is verified by comparing the obtained results with those obtained by mokhiamer (1999). figures (1) and (2) shows a comparison between the pressure distribution obtained in this work with that obtained by mokhiamer (1999) for eccentricity ratio of (0.4, 0.6) respectively. it can be shown from these figures that the maximum percentage of error between the obtained and the published results is (6.25% and 5%) respectively, while figure (3) shows that the maximum error between the attitude angle obtained during this work in comparison with that obtained by mokhiamer (1999) did not exceed (6%). the percentages of error mentioned above are based on the difference between the calculated and published data divided by the published data. it is clear from the above figures that the results obtained through this work are in a good agreement with the published results and give a reasonable reliability to the program used to analyze the problem of the present work. figure (4) shows that the load carrying capacity of the bearing decreases when combined misalignment (axial and twisting) which gives an indication that the oil film thickness increases when the bearing suffers from the combined misalignment is taken into consideration. a maximum decrease of (28%) in load carrying capacity is noticed in this case. a greater decreases in load carrying capacity is noticed when axial misalignment of the bearing is taken into consideration especially for low values of eccentricity ratio. the maximum reduction is calculated and found to be about (35%) , which indicates an increase in oil film thickness in this range of eccentricity ratios. a slight increase in load carrying capacity is noticed when the twisting misalignment is considered especially for low values of eccentricity ratio (i.e. to about  = 0.4) while it has no effect for higher values of eccentricity ratio. a decrease in attitude angle is seen when combined axial and twisting misalignment is taken into consideration as shown in figure (5). a maximum decrease is calculated and found to be (20%). this can be attributed to the variation in load carrying capacity components mentioned before. an increase in attitude angle is noticed when axial misalignment of the bearing is taken into consideration. this is due to the increase in oil film thickness in this case. a slight decrease in coefficient of friction is shown when the twisting misalignment is considered as shown in figure (6) , which indicates a lower shearing rate of the oil in this case. an increase in coefficient of friction is shown when twisting and combined misalignment calculate w,f -, ψ, s, q no yes if >0.95 2 =+0.05 print w ,f , ψ, s, q , ,1 , 2,lc end assume 1 , 2,lc 1 lekaa' h. abd al-shaheed al-khwarizmi engineering journal, vol. 8, no. 2, pp 42 53 (2012) 47 is taken into consideration. this is due to the increase of the shearing rate of the lubricant in this case. figure (7) shows that the side leakage flow rate of the bearing deceases when the axial misalignment of the journal bearing is taken into consideration. this can be attributed to the increase in oil film thickness, which affects the velocity component in axial direction, and the pressure gradient in circumferential direction. a decrease in side leakage flow rate of (20%), is noticed in this case. an increase in side leakage flow rate has been shown when axial and twisting misalignment of the journal bearing have been taken into consideration. a higher increase in side leakage is noticed when the twisting misalignment only is taken into consideration which indicate the increase in oil film thickness of the lubricant. figure (8) shows that the load carrying capacity for a porous bearing lubricated with couple stress fluid is higher than that obtained when the bearing lubricated with newtonian lubricant for different values of the eccentricity ratios. this can be attributed to the higher viscosity of the couple stress lubricant than that of newtonian lubricant. it is clear from this figure that a higher enhancement is obtained when the bearing is lubricated with couple stress lubricant of higher couple stress parameter (lc). about (40%) enhancement in load carrying capacity is shown for the bearing lubricated with a lubricant of couple stress parameter of (lc = 0.2). the bearing attitude angle is seen to have lower values for the bearing lubricated with couple stress lubricant than that lubricated with newtonian lubricant as shown in figure (9). this is attributed to the increase in load carrying capacity component mentioned above when lubricating the bearing with couple stress fluid. the decrease in attitude angle becomes higher when the bearing lubricated with couple stress lubricant of higher couple stress parameter. a decrease in friction coefficient of the bearing has is when the bearing lubricated with couple stress lubricant rather than that lubricated with newtonian lubricant as shown in figure (10). the decrease in coefficient of friction become higher when the bearing lubricated with a couple stress lubricant with higher couple stress parameter. this can be explained if we know that the load carrying capacity of the bearing is increased in this case, since the coefficient of friction is inversely proportional to the value of the load. figure (11) shows a slight increase in oil side leakage from the bearing lubricated with couple stress lubricant than that for lubricated with newtonian lubricant. a couple stress parameter (lc) is shown to have a slight effect on the oil side leakage of the bearing. a slight increase in oil side leakage is shown with increasing values of (lc). the increase oil side leakage can also be attributed to the effect of combined misalignment of the bearing which causes larger oil film thickness. the effect of length to diameter ratio of the bearing on the load carrying of the bearing is shown in figure (12) . it is clear that the load carrying capacity increase for the bearing with higher length to diameter ratio, while the coefficient of friction decreases as shown in figure (13). fig. 1. comparison pressure distribution between present and published result u.m.mokhiamer et. al. (1999) at ps= 0.1, lc =0.4,r/l=0.5 ,1=0.0 , 2=0.0 and =0.4. fig. 2. comparison pressure distribution between present and published result u.m.mokhiamer et. al. (1999) at ps= 0.1, lc =0.4,r/l=0.5 ,1=0.0 , 2=0.0 and =0.6. θ (degree) p 0 90 180 270 360 0 1 2 3 4 5 6 program results published results (1999) θ(degree) p 0 90 180 270 360 0 2 4 6 8 10 12 14 16 18 20 program results 91999) published results (1999) lekaa' h. abd al-shaheed al-khwarizmi engineering journal, vol. 8, no. 2, pp 42 53 (2012) 48 fig. 3. comparison attitude angle versus eccentricity ratio between present and published result u.m.mokhiamer et. al. (1999) at ps= 0.1, lc =0.4,r/l=0.5 ,1=0.0 , 2=0.0 and =0.4. fig. 4. load carrying capacity verse eccentricity ratio for different misalignment ratios at lc = 0.4. fig. 5. attitude angle verse eccentricity ratio for different misalignment ratios at lc = 0.4. fig. 6. coefficient of friction verse eccentricity ratio for different misalignment ratios at lc = 0.4.  ψ ( d e g r e e ) 1 = 2 = 1 = 2 = 1 = 2 = 1 = 2 = 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0 25 50 75 100 ps = 0.1 0.0007 , 0.0007 0.0007 , 0.0 0.0 , 0.0007 0.0 , 0.0  f( r /c ) 1 = 2 = 1 = 2 = 1 = 2 = 1 = 2 = 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0 1 10 100 ps = 0.1 0.0007 , 0.0007 0.0007 , 0.0 0.0 , 0.0007 0.0 , 0.0 ψ ( d e g re e ) 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 10 20 30 40 50 60 70 80 90 program results published results (1999)  w  1 = 2 = 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0.1 1.0 10.0 100.0 1000.0 ps = 0.1 0.0007 , 0.0007 0.0007 , 0.0 0.0 , 0.0007 0.0 , 0.01 = 2 = 1 = 2 = 1 = 2 = lekaa' h. abd al-shaheed al-khwarizmi engineering journal, vol. 8, no. 2, pp 42 53 (2012) 49 fig. 7. dimensionless side flow verse eccentricity ratio for different misalignment ratios at lc = 0.4. fig. 8. load carrying capacity verse eccentricity ratio for various values of couple stress parameter. fig. 9. attitude angle verse eccentricity ratio for various values of couple stress parameter. fig. 10. coefficient of friction verse eccentricity ratio for various values of couple stress parameter.  q 1 = 2 = 1 = 2 = 1 = 2 = 1 = 2 = 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0.0 0.5 1.0 1.5 2.0 ps = 0.1 0.0007 , 0.0007 0.0007 , 0.0 0.0 , 0.0007 0.0 , 0.0  w 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0.0 0.1 1.0 10.0 100.0 1000.0 a = 1 = 0.0007 = 0.0007 = 0.0 = 0.2 = 0.4 = 0.6 1 2 lc lc lc lc  ψ ( d e g r e e ) 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10 20 30 40 50 60 70 80 90 100 1 2 lc lc lc lc  f( r /c ) 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0.01 0.10 1.00 10.00 100.00 a = 1 = 0.0007 = 0.0007 = 0.0 = 0.2 = 0.4 = 0.6 1 2 lc lc lc lc lekaa' h. abd al-shaheed al-khwarizmi engineering journal, vol. 8, no. 2, pp 42 53 (2012) 50 fig. 11. dimensionless side flow verse eccentricity ratio for various values of couple stress parameter. fig. 12. load carrying capacity verse eccentricity ratio for various values of l/d ratios. fig. 13. friction factor verse eccentricity ratio for various values of l/d ratios. 4. conclusions on the basis of microcontinum theory developed by stokes, the present investigation reveals the effect of couple stresses on the performance of misaligned finite length porous journal bearing. the results obtained through this work leads to the following main conclusions: 1the journal center misalignment has a considerable effect on the performance parameters of the bearing which can not be neglected. the presence of combined misaligned (axial and twisting) causes a decreases of the load carrying capacity and attitude angle. 2the presence of bearing axial misalignment causes a slight increase in load carrying capacity and attitude angle, while a decrease in side leakage of the bearing, is noticed in this case. 3using the coupled stress fluid as a lubricant seems to improve some of the steady state characteristics of the porous bearings in comparison with the bearing lubricated with newtonian lubricant. an increase in load carrying capacity, a decrease in attitude angle, friction coefficient and slight increase in side leakage flow have been noticed. 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0.01 0.10 1.00 10.00 100.00 = 0.4 = 0.0007 = 0.0007 = 0.5 = 0.8 = 1.0 = 1.2  w 1 2 l/ d l/ d l/ d l/ d lc 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0.0 0.5 1.0 1.5 2.0  q 1 2 lc lc lc lc  f( r /c ) 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0.01 0.10 1.00 10.00 100.00 = 0.4 = 0.0007 = 0.0007 = 0.5 = 0.8 = 1.0 = 1.2 1 2 lc l/ d l/ d l/ d l/d lekaa' h. abd al-shaheed al-khwarizmi engineering journal, vol. 8, no. 2, pp 42 53 (2012) 51 5. nomenclature the following symbols are used throughout this work. a ratio of length to diameter c journal bearing clearance (m) d diameter of bearing (m) f friction force (n) f ^ dimensionless friction force , f ^ = (fc/jr 2 l) f ^ dimensionless friction coefficient, f  = (r/c)f h ^ dimensionless film thickness, ( h ^ =h/c) l length of the bearing (m) lc characteristics length of the additive lc ^ dimensionless coupled stress parameter , lc ^= lc/c k permeability parameter (m 2 ) nj journal rotational speed (r.p.m) p ^ dimensionless oil-film pressure, p ^ =c 2 p/(r 2 j) p ^* dimensionless oil – film pressure inside the porous matrix, p ^* =c 2 p * /(r 2 j) ps supply pressure(n/m 2 ) q ^ s dimensionless side leakage flow, q ^ s = qs l/ujr 2 c r ^ normalized radial coordinate, r ^ = r/ri rj inner radius of porous bearing (m) ro outer radius of porous bearing (m) ri inner radius (m) ro outer radius (m) s sommerfeld number , s= (rjl / w)*(ri / c) 2 uj journal velocity (m/s) w ^ dimensionless load carrying capacity, w ^ =(w c 2 / j 3 i r l) w ^ r dimensionless component of oil film force along the line of centers w ^ t dimensionless component of oil film force perpendicular to the line of centers y ^ dimensionless bearing coordinates in axial direction, y ^ =y/h z ^ non – dimensional axial coordinate z ^ =z/l greek symbols  eccentricity ratio  absolute viscosity of lubricant (pa . s)  material constant responsible for the couple stress parameter  angular coordinate from maximum film thickness position (degree)  density of oil (kg/m 3 )  porous layer thickness (m) φ permeability parameter , φ= k*/c 3  attitude angle (degrees) r, , z bearing coordinates in radial, circumferential and axial directions. 1 ,2 tilt angles (rad) 1 , 2 two independent misalignment parameters  normalized axial coordinate ( z/l ) j journal rotational speed (rad/sec) subscript b referring to bearing j referring to journal superscript  dimensionless quantity  porous parameter 6. references [1] c. cusano, , 1979, "an analytical study of starved porous bearings", transactions of the asme, january, vol. 101, pp. 38 – 47. [2] s. kaneko, , 1989, "static and dynamic characteristics of porous journal bearings with anisotropic permeability" jsme international journal, series iii, vol. 32, no. 1, 1989. [3] s. kaneko, and s. obara, , 1990, "experimental investigation of mechanism of lubrication in porous journal bearings: part 1observation of oil flow in porous matrix", transaction of asme, october, vol. 112, pp. 618 – 623. [4] n. m. bujurke and h. p. patil, , 1991, "an analysis of squeeze film action in porous layered bearings", wear, 145, pp. 385 – 397. [5] kaneko, s., ohkawa, y., hashimoto, y., 1994, "a study of mechanism of lubrication in porous journal bearings: effect of dimensionless oil –feed pressure on static characteristics under hydrodynamic lubrication conditions", lekaa' h. abd al-shaheed al-khwarizmi engineering journal, vol. 8, no. 2, pp 42 53 (2012) 52 transactions of the asme, july, vol. 116, pp. 606 – 611. [6] s. kaneko, and y. hashimoto, 1995, "a study of the mechanism of lubrication in porous journal bearings: effect of dimensionless oil – feed pressure on frictional characteristics", journal of tribology, april, vol. 117, pp. 291 – 296. [7] s. kaneko, y. hashimoto, and i. hiroki, 1997, "analysis of oil – film pressure distribution in porous journal bearings under hydrodynamic lubrication conditions using an improved boundary condition", journal of tribology, january, vol. 119, pp. 171 – 178. [8] yasunaga mitsuya, zhisheng deng, and masahiro ohka, 1997, "derivation of rarefaction – modified reynolds equation considering porosity of thin lubricant film", journal of tribology, october, vol. 119, pp. 653 – 659. [9] t. ariman, m. a. turk, and n. d. sylvester, 1973, "microcontinuum fluid mechanics – a review" , int. engng sci., vo. 11, pp. 905 – 930. [10] t. ariman, m. a. turk, and n. d. sylvester, 1974, "application of microcontinuum fluid mechanics” int.j. engng sci., vo. 12, pp. 273. [11] n. b. naduvinamani. p. s. hiremath, and g. gurubasavaraj, 2001, "squeeze film lubrication of a short porous journal bearing with couple stress fluids", tribology international, 34, pp. 739 – 747. [12] n. b. naduvinamani. p. s. hiremath, and g. gurubasavaraj, 2002, "surface roughness effects in a short porous journal bearing with couple stress fluid", fluid dynamic research, 31, pp. 333 – 354. [13] n. m. bujurke, and ramesh b. kudenatti, 2006, "an analysis of rough poroelastic bearings with reference to lubrication mechanism of synovial joints", applies mathematics and computation , 178, pp. 309 – 320. [14] d. srinivasacharya , n. srinivasecharyulu and o. odelu, 2009, "flow and heat transfer of couple stress fluid in a porous channel with expanding and contracting walls", international communications in heat and mass transfer, 36, pp. 180 – 185. [15] n. b. naduvinamani and s. b. patil, 2009, "numerical solution of finite modified reynolds equation for couple stress squeeze film lubrication of porous journal bearings", computers and structures, 87, pp. 1287 – 1295. [16] u. m. mokhiamer, w. a. crosby and h. a. el – gamal, 1999, "astudy of a journal bearing lubricated by fluid with couple stress considering the elasticity of the liner", wear, 224, pp. 194 – 201. [17] y. jin jang and chong – ching chang, 1987, "adiabatic solutions for a misaligned journal bearing with non – newtonian lubricants", tribology international, vol. 20, no. 5, pp. 267 – 275 [18] jaw – ren lin, 1997, "effect of couple stresses on the lubrication of finite journal bearings", wear, 206, pp. 171 – 178. (2012 )42 53 ، صفحة2، العذد 8 مجلة الخىارزمي الهنذسية المجلذ لقاء حميذ عبذ الشهيذ 53 المحىر على الخصائص الساكنة للمسانذ المقعذية راتية التسييت المشبعة بمائع انحرافتأثير رو أجهاد مسدوج لقاء حميذ عبذ الشهيذ جايعت بابم /قسى انهُذست انًٍكاٍَكٍت lekaa_hameed@yahoo.com:انبشٌذ االنكخشوًَ الخالصة . ٌخضًٍ هزا انبحذ دساست َظشٌت نخأرٍش أَحشاف انًحىس عهى انخصائص انساكُت نهًساَذ انًقعذٌت راحٍت انخضٌٍج انًشبعت بًائع رو أجهاد يضدوج يع األخز بُظش االعخباس انُفارٌت انًُخظًت نهًسُذ انًقعذي فاٌ . انًىدٌم انخحهٍهً انًسخخذو فً انبحذ انحانً ٌخخص بانًساَذ راث انُفارٌت يُخظًت انخىصٌع يعادنت انضغظ نهطبقت انًسايٍت اسخحصهج يٍ يعادنت . (انضٌج يضدوج األجهاد)يعادنت سٌُىنذص عذنج نخأخز بُظش االعخباس حأرٍش انُفارٌت وَىعٍت انضٌج الحخساب سًك طبقت انضٌج عذنج نخأخز بُظش االعخباس حأرٍش اَحشاف انًحىس باالحجاهٍٍ انطىنً ثانًعادنت انخً اسخخذو. داسسً ويعادنت االسخًشاسٌت حى أعذاد بشَايج حاسىبً نحم انًعادالث انحاكًت . حى حم انًعادالث انحاكًت يع انششوط انحذٌت انًُاسبت عذدٌا باسخخذاو حقٍُت عذدٌت يُاسبت. ضوانًسخعش وقذ أظهشث عًهٍت ةوحى انخأكذ يٍ يىرىقٍت انبشَايج عٍ طشٌق يقاسَت بعط انُخائج انًسخحصهت فً هزا انبحذ يع حهك انًُشىسة فً بعط انبحىد انًخىفش ويٍ خالل يقاسَت حصشف انًساَذ انًُحشفت وانغٍش يُحشفت وجذ بأٌ الَحشاف يحىس انًسُذ . انًقاسَت حقاسبا جٍذا فً انُخائج انًسخحصهت يع حهك انًُشىسة .انًقعذي حأرٍشا ال ًٌكٍ إهًانه mailto:lekaa_hameed@yahoo.com mailto:lekaa_hameed@yahoo.com 110 al-khwarizmi engineering journal,vol. 11, no. the influence of the magnetic abrasive finishing cylindrical surfaces marwa k. qate’a* *, **, ***department of automated manufacturing engineering (received abstract magnetic abrasive finishing (maf) is one of the advanced finishing processes, which produces a high level of surface quality and is primarily controlled by a magnetic field. finishing system on the material removal rate (mrr) and surface roughness (ra) in terms of magnetic abrasive finishing system for eight of input parameters, regression model to analysis the output (results) magnetic poles, grain size powder, doze of the ferromagnetic abrasive powder magnetic poles velocity, and finishing time) of maf machine and magnetic poles, preparing ferromagnetic abrasive powder by mix the iron oxide with industrial diamond powder and studying the effects of m software was used to estimate the influence of the magnetic abrasive finishing (maf) parameters on the mrr and surface roughness for a cylindrical duralumin (2024) workpiece. the biggest influence on mrr (30.18%) followed by finishing time, gap, magnetic poles velocity, workpiece velocity, current, doze, and grain size powder, respectively. also the results show that the workpiece velocity influence on the surface roughness (23.80%) followed by doze, gap, current, poles geometry angle, magnetic poles velocity, grain size powder, and finishing time, respectively. regression results show that the decreasing of poles geometry angle from 30°to -30° leads to increasing mrr. while the decreasing of the workpiece velocity from (679 rpm) to (567 rpm) leads to increase the roughness. keywords: magnetic abrasive finishing process, 1. introduction the maf process removes a very small amount of material by indentation and rotation of magnetic abrasive particles in the circular tracks. the working principle of maf method is that the workpiece is kept between the two poles of a magnet. the working gap between and the magnet is filled with magnetic abrasive particles. a magnetic abrasive flexible brush (mafb) is formed, acting as a multipoint cutting tool which pushes against the workpiece surface khwarizmi engineering journal,vol. 11, no. 3, p.p. 110 (2015) of the magnetic abrasive finishing cylindrical surfaces on the surface roughness and mrr * ali h. kadhum** faiz f. mustafa department of automated manufacturing engineering / al-khwarizmi college of engineering university of baghdad *email: marwa90_alkaabi@yahoo.com **email: kadhumali59@yahoo.com ***email: faizalrawy@yahoo.com (received 21 may 2014; accepted 16 june 2015) magnetic abrasive finishing (maf) is one of the advanced finishing processes, which produces a high level of surface quality and is primarily controlled by a magnetic field. this paper study the effect of the magnetic abrasive on the material removal rate (mrr) and surface roughness (ra) in terms of magnetic abrasive input parameters, and three levels according to taguchi array (l27) and us to analysis the output (results). these parameters are the (poles geometry angle, doze of the ferromagnetic abrasive powder, dc current, workpiece velocity, city, and finishing time). this work includes the classification of the maf system, implementation of maf machine and magnetic poles, preparing ferromagnetic abrasive powder by mix the iron oxide with industrial diamond powder and studying the effects of magnetic abrasive finishing on the mrr and surface roughness. minitab estimate the influence of the magnetic abrasive finishing (maf) parameters on the mrr and surface roughness for a cylindrical duralumin (2024) workpiece. the results show that the poles geometry angle has the biggest influence on mrr (30.18%) followed by finishing time, gap, magnetic poles velocity, workpiece velocity, current, doze, and grain size powder, respectively. also the results show that the workpiece velocity influence on the surface roughness (23.80%) followed by doze, gap, current, poles geometry angle, magnetic poles velocity, grain size powder, and finishing time, respectively. regression results show that the decreasing of poles 30° leads to increasing mrr. while the decreasing of the workpiece velocity from (679 rpm) to (567 rpm) leads to increase the roughness. magnetic abrasive finishing process, regression model, material removal rate, surface roughness. process removes a very small amount of material by indentation and rotation of magnetic abrasive particles in the circular tracks. the working principle of maf method is that the workpiece is kept between the two poles of a magnet. the working gap between the workpiece and the magnet is filled with magnetic abrasive particles. a magnetic abrasive flexible brush (mafb) is formed, acting as a multipoint cutting which pushes against the workpiece surface and develops finishing pressure of the magnetic field in the working gap [ finishing is a type of machining technology for greatly increasing the surface quality of a machined object while maintaining stable precision and improving the machining precision grade [4]. surface finish h important functional properties such as wear resistance and power losses due to friction on most of the engineering components [ external finishing of cylindrical surface shown in fig. 1, cylindrical workpiece rotates between the magnetic poles, the magnetic al-khwarizmi engineering journal 10 (2015) system for on the surface roughness and mrr mustafa*** warizmi college of engineering/ magnetic abrasive finishing (maf) is one of the advanced finishing processes, which produces a high level of study the effect of the magnetic abrasive on the material removal rate (mrr) and surface roughness (ra) in terms of magnetic abrasive three levels according to taguchi array (l27) and using the poles geometry angle, gap between the two , dc current, workpiece velocity, this work includes the classification of the maf system, implementation of maf machine and magnetic poles, preparing ferromagnetic abrasive powder by mix the iron oxide with industrial agnetic abrasive finishing on the mrr and surface roughness. minitab estimate the influence of the magnetic abrasive finishing (maf) parameters on the mrr and show that the poles geometry angle has the biggest influence on mrr (30.18%) followed by finishing time, gap, magnetic poles velocity, workpiece velocity, current, doze, and grain size powder, respectively. also the results show that the workpiece velocity has the biggest influence on the surface roughness (23.80%) followed by doze, gap, current, poles geometry angle, magnetic poles velocity, grain size powder, and finishing time, respectively. regression results show that the decreasing of poles 30° leads to increasing mrr. while the decreasing of the workpiece velocity from (679 model, material removal rate, surface roughness. and develops finishing pressure, due to the effect of the magnetic field in the working gap [1-3]. finishing is a type of machining technology for greatly increasing the surface quality of a machined object while maintaining stable precision and improving the machining precision surface finish has a vital influence on important functional properties such as wear resistance and power losses due to friction on most of the engineering components [5]. in external finishing of cylindrical surface that , cylindrical workpiece rotates between the magnetic poles, the magnetic marwa k. qate’a abrasive powder filled the both gaps on either sid between the workpieces and magnetic poles in maf, magnetic abrasives which play the role of cutting tools are very crucial in finishing of desired quality and accuracy. magnetic abrasives can be of different types like mechanical mixture of abrasives and magnetic powder, sintered type, bonded type, type. fig. 1. scheme of magnetic abrasive finishing (maf): external finishing. 2. prevoius literatures yahya m. hamad [6] has implemented the method for finishing and improving the quality of the ferromagnetic stainless steel 420 plate. it was found that changing the operation parameters (working gap, coil current, feed rate, and table stroke) will affect the quality of workpiece surface. wang and hu [7] proposed maf process for producing highly finished surfaces of tubes. this study showed the feasibility of using a maf with a mixture of conventional and ferrous particles for the internal finishing of three kinds of metal tubes, such as ly12 aluminum alloy, 316l stainless steel and h62 bras.f. djavanroodi [8] has studied the parameter that affects surface roughness in maf process on a brass shaft of cuzn37. these parameters are: intensity of the magnetic field, workpiece velocity and finishing time. it has been shown that the intensity of magnetic field has the most effect on finishing process, a higher intensity in magnetic field, results in a higher change in surface roughness, increasing finishing time results in decreased surface roughness and a lower workpiece velocity leads to a lower surface roughness. jae-seob and tae-kyung performed maf on the magnesium material and design of experimental method using the taguchi al-khwarizmi engineering journal, vol. 11, no. 2 abrasive powder filled the both gaps on either side between the workpieces and magnetic poles [2]. in maf, magnetic abrasives which play the role of cutting tools are very crucial in ensuring finishing of desired quality and accuracy. magnetic abrasives can be of different types like mechanical mixture of abrasives and magnetic bonded type, and unbonded of magnetic abrasive finishing has implemented the maf method for finishing and improving the quality of the ferromagnetic stainless steel 420 plate. it was found that changing the operation parameters oil current, feed rate, and table stroke) will affect the quality of workpiece proposed maf process for producing highly finished surfaces of tubes. this study showed the feasibility of using a maf with a mixture of conventional abrasives and ferrous particles for the internal finishing of three kinds of metal tubes, such as ly12 aluminum alloy, 316l stainless steel and h62 has studied the parameter that affects surface roughness in maf haft of cuzn37. these parameters are: intensity of the magnetic field, workpiece velocity and finishing time. it has been shown that the intensity of magnetic field has the most effect on finishing process, a higher intensity a higher change in surface roughness, increasing finishing time results in decreased surface roughness and a lower workpiece velocity leads to a lower surface kyung [9] was performed maf on the magnesium material and xperimental method using the taguchi method was applied to evaluate parameter’s effect on the surface roughness using fe powder and boron nitride as magnetic abrasive powder, it was seen that better surface roughness could be obtained by applying the maf p 3. regression model regression is a statistical measure that attempts to determine the strength of the relationship between one dependent variable (mrr & surface roughness) changing variables (known as independent variables) (poles geometry angle, two magnetic poles, grain size powder, the ferromagnetic abrasive powder workpiece velocity, magnetic poles velocity, and finishing time). the two basic types of regression are linear regression an linear regression and multiple regressions which are use two or more independent variables to predict the outcome. the general form of each type of regression is: multiple regression: y = a + b ... + btx t + u where: y= the variable that we are trying to predict x= the variable that we are using to predict y a= the constant b= the slope u= the regression residual regression takes a group of random variables, thought to be predicting y, and tries to find a mathematical relationship between them. this relationship is typically in the form of a straight line (linear regression) that best approximates all the individual data points. 4. taguchi array the taguchi arrays can be derived or looked up. small arrays can be drawn out manually; large arrays can be derived from deterministic algorithms. generally, arrays can be found online. the arrays are selected by the number parameters (variables) and the number of levels (states). khwarizmi engineering journal, vol. 11, no. 3, p.p. 110 (2015) method was applied to evaluate parameter’s effect on the surface roughness using fe powder and boron nitride as magnetic abrasive powder, it was seen that better surface roughness could be obtained by applying the maf process. a statistical measure that attempts to determine the strength of the relationship between one dependent variable (mrr & surface roughness) and a series of other changing variables (known as independent poles geometry angle, gap between the rain size powder, doze of the ferromagnetic abrasive powder, dc current, workpiece velocity, magnetic poles velocity, and the two basic types of regression are linear regression and multiple regressions. linear regression and multiple regressions which are use two or more independent variables to predict the outcome. the general form of each multiple regression: y = a + b1x1 + b2x2 + b3x3 + …(1) y= the variable that we are trying to predict x= the variable that we are using to predict y regression takes a group of random variables, thought to be predicting y, and tries to find a mathematical relationship between them. this relationship is typically in the form of a straight line (linear regression) that best approximates all the taguchi arrays can be derived or looked up. small arrays can be drawn out manually; large arrays can be derived from deterministic algorithms. generally, arrays can be found online. the arrays are selected by the number of parameters (variables) and the number of levels marwa k. qate’a al-khwarizmi engineering journal, vol. 11, no. 3, p.p. 110 (2015) 3 5. experimental work 5.1. maf system parameters first step in the experimental work was the classification of maf system into: (1) machine parameters (2) fixture (3) tool (4) workpiece (5) electro-magnetic system (6) maf output. this parameter includes all the input and output parameters have been used in the maf process that is shown in fig.2. solid duralumin 2024 material with cylindrical shape was chosen to be a workpiece with a diameter of 60 mm, and length of 300 mm, it is having a high strength and fatigue resistance. the chemical composition and some properties of duraluminum 2024 are given in table 1. 5.2. design and implementation of maf machine maf machine for the cylindrical surface has been designed and manufactured in the alkhwarizmi engineering college workshop; the basic components that have been used to form the maf machine illustrated as following: (1) two gearbox motor (changeable velocities), (2) solid iron square shaft (32 mm), with a length of (890 mm), (3) copper wires (1 mm) diameter that have been used to manufacture the magnetic coils. (4) lathe machine that has been used as a base frame of the maf machine, (5) insulated base that has been manufactured from the perspex material. (6) two power supply one for the coil to control the magnetic and the other to control the velocity of motors, (7) electrical motor used for rotating the workpiece, (8) stand for carry the whole maf machine which has been carried out some modifications on it to suit their required purpose, (9) two axial shafts. the manufacturing of the maf machine has been done by the following steps: (a) the solid square shaft has been perforated from the two sides with depth of 100 mm and 11 mm diameter according to the diameter of the magnetic poles. (b) bending the solid square shaft in the form of horseshoe from the two sides to make the two basic magnetic poles. (c) prepare two discal barriers for the purpose of winding the copper wire. (d) insulating the solid square shaft from the two discal barriers and then turn the copper wire around the shaft with number of turns equal to 1600 cycle to form the magnetic coil. (e) manufacturing three couples of magnetic poles for the purpose of polarization the ferromagnetic abrasive powder. the magnetic poles have been designed and manufactured to rotate each against the other to maintain a high magnetic field, maintain a biggest amount of the ferromagnetic abrasive powder and to avoid the centrifugal force. fig.3 shows the whole maf machine. fig. 2. input and output for the finishing system for maf . marwa k. qate’a al-khwarizmi engineering journal, vol. 11, no. 3, p.p. 110 (2015) 4 table 1, the chemical composition and properties of duraluminum 2024. fig. 3. photograph of the maf machine. 5.3. preparing the ferromagnetic abrasive powder ferromagnetic abrasive powder is an essential part in the maf process; the preparing of the ferromagnetic abrasive powder was done by mixing 67% from iron oxide with 33% from industrial diamond using liquid epoxy and then enter this mixture in to a furnace at a temperature between 300 400°c for a time of 45 minute, then remove it from the furnace and leave it to air cool, after that we grind it by using a high speed grinder , finally we use a sieve to extracted three types of powder grain size diameters (100, 200, and 300 µm). 5.4. manufacturing of magnetic poles three couples of magnetic poles have been designed according to three different angles (30°, 0°, and -30°); a rounded iron shaft has been used to manufactured these magnetic poles, using the lathe machine to obtain the desired shapes and then toothing them with milling machine in a form of projections triangular as shown in fig.4. fig. 4. the three manufactured magnetic poles. 5.5. selection of input parameters values in this work eight inputs parameters have been choose with three levels according to the classification of maf system. the values of inputs parameters illustrated in table 2. the input parameters is been applied it on a set of experiments, according to the taguchi array (l27), which deals with the number of the input parameters, and the number of level, so that l27 has been selected. table 2, inputs parameters values. chemical composition cu mg mn al properties ρ (g/cm3) e (gpa) tm (°c) w% 4.4 1.5 0.6 93.5 value 2.78 73 500 input parameter level level 1 level 2 level 3 poles geometry angle (deg.) 30 0 -30 gap (mm) 1.5 2.5 3.5 grain size powder (µm) 100 200 300 doze (cc) 18 24 30 current (amp.) 3 6 9 workpiece velocity (rpm) 567 629 679 magnetic poles velocity (rpm) 208 347 496 finishing time (sec) 30 45 60 marwa k. qate’a al-khwarizmi engineering journal, vol. 11, no. 3, p.p. 110 (2015) 5 6. experimental results of maf processes after all the experiments of maf process was completed, the weight and the surface roughness for each workpiece were calculated. the weight is calculated as the following: ∆w = weight (before maf) – weight (after maf), while ∆ra calculated using surface roughness tester, (tr220) and by the measuring for each workpiece three times before maf and three times after maf, and get the midrange value, then we take the difference between the two cases. fig.5 shows the duraluminum workpiece before and after the maf process. based on the experiments of the maf process, a set of input / output training data for the regression models is generated. table 3 shows this data set in both cases of consideration the material removal rate and surface roughness is the outputs. fig. 5. duralumin workpiece before after maf process. table 3, training data sets for the proposed mode. w.p no. poles geometry angle (deg.) gap (mm) grain size powder (µµµµm) doze (cc) current (amp.) workpiece velocity (rpm) magnetic poles velocity (rpm) finishing time (sec.) ∆w (g) ∆ra (µµµµm) 1 30 1.5 100 18 3 567 208 30 0.0018 0.029 2 30 1.5 100 18 6 629 347 45 0.0027 0.036 3 30 1.5 100 18 9 679 496 60 0.0019 0.002 4 30 2.5 200 24 3 567 208 45 0.0007 0.007 5 30 2.5 200 24 6 629 347 60 0.0007 0.039 6 30 2.5 200 24 9 679 496 30 0.0003 0.092 7 30 3.5 300 30 3 567 208 60 0.0018 0.053 8 30 3.5 300 30 6 629 347 30 0.0006 0.08 9 30 3.5 300 30 9 679 496 45 0.0003 0.074 10 0 1.5 200 30 3 629 496 30 0.0051 0.147 11 0 1.5 200 30 6 679 208 45 0.0054 0.016 12 0 1.5 200 30 9 567 347 60 0.0072 0.289 13 0 2.5 300 18 3 629 496 45 0.0059 0.203 14 0 2.5 300 18 6 679 208 60 0.0073 0.144 15 0 2.5 300 18 9 567 347 30 0.0059 0.089 16 0 3.5 100 24 3 629 496 60 0.0152 0.006 17 0 3.5 100 24 6 679 208 30 0.0061 0.069 18 0 3.5 100 24 9 567 347 45 0.0126 0.054 19 -30 1.5 300 24 3 679 347 30 0.394 0.07 20 -30 1.5 300 24 6 567 496 45 0.001 0.218 21 -30 1.5 300 24 9 629 208 60 0.0135 0.015 22 -30 2.5 100 30 3 679 347 45 0.0014 0.078 23 -30 2.5 100 30 6 567 496 60 0.0258 0.11 24 -30 2.5 100 30 9 629 208 30 0.0286 0.042 25 -30 3.5 200 18 3 679 347 60 0.0197 0.052 26 -30 3.5 200 18 6 567 496 30 0.0216 0.059 27 -30 3.5 200 18 9 629 208 45 0.0215 0.05 marwa k. qate’a 7. results and discussion 7.1. regression model by using minitab software the regression equation for estimate the surface roughness and mrr has been obtained as the following: y1 (∆w) = 0.076 – 0.000956 x1 0.000186 x3 0.00011 x4 0.00655 x5 + 0.000342 x6 0.000007 x7 0.00137 x8 y2 (∆ra) = 0.136 0.000522 x1 0.000289 x3+ 0.00208 x4 + 0.00115 x5 0.000317 x6+ 0.000186 x7 + 0.00012 x8 where: x1: poles geometry angle (deg). x2: gap (mm). x3: grain size powder (µm). x4: doze (cc). x5: current (amp). x6: workpiece velocity (rpm). x7: magnetic poles velocity (rpm). x8: finishing time (sec). 7.2. the effect of poles geometry (x1) the relationship between poles geometry angle x1 with mrr y1 and surface roughness y2 shown in fig. 6.the mean value of y1 at x1 = 0.0585667 g, at x1 = 0° is 0.00785556 g, and at x1 = 30° is 0.0012 g. poles geometry is affected by 30.180 % on the mrr; decreasing x1 from 30° to -30° leads to increasing mrr. the best value of poles geometry angle in this case is ( the mean value of y2 at x1 = -30° is 0.0771111 µm, at x1 = 0° is 0.113 µm, and at x1 = 30° is 0.0457778 µm. poles geometry angle is affected by 10.053 % on the surface roughness; decreasing of x1 from 30° to 0° leads to increas decreasing it from 0° to -30° leads to decreasing ra. the best value of poles geometry angle in this case is (0°). 7.3. the effect of gap (x2) the relationship between gap x2 with mrr y1 and surface roughness y2 shown in fig. 7 mean value of y1 at x2 = 1.5 mm is 0.0480667 g, at x2 = 2.5 mm is 0.00851111 g, and at x2 = 3.5 al-khwarizmi engineering journal, vol. 11, no. 6 by using minitab software the regression equation for estimate the surface roughness and mrr has been obtained as the following: 0.000956 x1 0.0185 x2 + 0.00011 x4 0.000007 x7 ... ( 2) 0.0181 x2 + 0.000289 x3+ 0.00208 x4 + 0.000317 x6+ 0.000186 x7 + ... (3) of poles geometry angle the relationship between poles geometry angle ace roughness y2 shown .the mean value of y1 at x1 = -30° is 0.0585667 g, at x1 = 0° is 0.00785556 g, and at x1 = 30° is 0.0012 g. poles geometry is affected by 30.180 % on the mrr; decreasing x1 from 30° to 30° leads to increasing mrr. the best value of n this case is (-30°). while 30° is 0.0771111 m, and at x1 = 30° is m. poles geometry angle is affected by 10.053 % on the surface roughness; decreasing of x1 from 30° to 0° leads to increasing ra, but 30° leads to decreasing ra. the best value of poles geometry angle in this the relationship between gap x2 with mrr shown in fig. 7. the mean value of y1 at x2 = 1.5 mm is 0.0480667 g, at x2 = 2.5 mm is 0.00851111 g, and at x2 = 3.5 mm is 0.0110444 g. gap is affected by 18.126 % on the mrr; decreasing x2 from3.5 to 2.5 mm leads to decrease mrr, but decreasing it from 2.5 to 1.5 mm leads to increase mrr. the best value of gap in this case is (1.5 mm). while the mean value of y2 at x2 = 1.5 mm is 0.0913333 x2 = 2.5 mm is 0.0893333 mm is 0.0552222 µm. gap is affected by16.133 % on the surface roughness; decreas 3.5 to 1.5 mm leads to increasing ra. the best value of gap in this case is (1.5 mm). fig. 6. the relationship between x1 fig. 7. the relationship between x2 and y1, y2. 7.4. the effect of grain size powder (x3) the relationship between grain size powder x3 with mrr y1 and surface roughness y2 fig.8. the mean value of y1 at x3 = 100 0.0106778 g, at x3 = 200 µ at x3 = 300 µm is 0.0478111 g. the grain size powder is affected by 1.156 % on the mrr; increasing x3 from 100 to 200 khwarizmi engineering journal, vol. 11, no. 3, p.p. 110 (2015) mm is 0.0110444 g. gap is affected by 18.126 % on the mrr; decreasing x2 from3.5 to 2.5 mm leads to decrease mrr, but decreasing it from 2.5 ads to increase mrr. the best value of gap in this case is (1.5 mm). while the mean value of y2 at x2 = 1.5 mm is 0.0913333 µm, at x2 = 2.5 mm is 0.0893333 µm, and at x2 = 3.5 m. gap is affected by16.133 % on the surface roughness; decreasing of x2 from 3.5 to 1.5 mm leads to increasing ra. the best value of gap in this case is (1.5 mm). ip between x1 and y1, y2. fig. 7. the relationship between x2 and y1, y2. t of grain size powder (x3) the relationship between grain size powder x3 with mrr y1 and surface roughness y2 shown in . the mean value of y1 at x3 = 100 µm is µm is 0.00913333 g, and m is 0.0478111 g. the grain size powder is affected by 1.156 % on the mrr; increasing x3 from 100 to 200 µm leads to marwa k. qate’a al-khwarizmi engineering journal, vol. 11, no. 3, p.p. 110 (2015) 7 decrease mrr, but increasing it from 200 to 300 µm leads to increase mrr. the best value of grain size powder in this case is (300 µm), while the mean value of y2 at x3 = 100 µm is 0.0473333 µm, at x3 = 200 µm is 0.0834444 µm, and at x3 = 300 µm is 0.105111 µm. the grain size powder is affected by 7.088 % on the surface roughness; increasing the grain size powder from 100 to 300 µm leads to increasing ra. the best value of the grain size powder in this case is (300 µm). 7.5. the effect of doze (x4) the relationship between doze x4 with mrr y1 and surface roughness y2 shown in fig. 9. the mean value of y1 at x4 = 18 cc is 0.00981111 g, at x4 = 24 cc is 0.0493444 g, and at x4 = 30 cc is 0.0084667 g. doze is affected by 3.407 % on the mrr; increasing x4 from 18 to 24 cc leads to increasing mrr, but increasing it from 24 to 30 cc leads to decreasing mrr. the best value of doze in this case is (24 cc), while the mean value of y2 at x4 = 18 cc is 0.0737778 µm, at x4 = 24 cc is 0.0633333 µm, and at x4 = 30 cc is 0.0987778 µm. doze is affected by 18.063 % on the surface roughness; increasing x4 from 18 to 24 cc leads to decreasing ra, but increasing it from 24 to 30 cc leads to increasing ra. the best value of doze in this case is (30 cc). fig. 8. the relationship between x3 and y1, y2. fig. 9. the relationship between x4 and y1, y2. 7.6. the effect of the current (x5) the relationship between current x5 with mrr y1 and and surface roughness y2 shown in fig. 10. the mean value of y1 at x5 = 3 amp is 0.0495111 g, at x5 = 6 amp is 0.00791111 g, and at x5 = 9 amp is 0.0102 g. crrent is affected by 4.935 % on the mrr; decreasing x5 from 9 to 6 amp leads to decrease mrr, but decreasing it from 6 t0 3 amp leads to increasing mrr. the optimal value of current in this case is (3 amp), while the mean value of y2 at x5 = 3 amp is 0.0716667 µm, at x5 = 6 amp is 0.0856667 µm, and at x5 = 9 amp is 0.0785556 µm. current is affected by 13.394 % on the surface roughness; increasing x5 from 3 to 6 amp leads to increase ra, but increasing it from 6 t0 9 amp leads to decreasing ra. the best value of current in this case is (6 amp). fig. 10. the relationship between x5 and y1, y2. marwa k. qate’a 7.7. the effect of workpiece velocity (x6) the relationship between workpiece velocity x6 with mrr y1 and surface roughness y2 in fig. 11. the mean value of y1 at x6 = 567 rpm is 0.00871111 g, at x6 = 629 rpm is 0.0104222 g, and at x6 = 679 rpm is 0.0484889 g. the workpiece velocity is affected by 5.199 % on the mrr; increasing x6 from 567 to 679 rpm leads to increase mrr. the best value of workpiece velocity in this case is (679 rpm), while the mean value of y2 at x6 = 567 rpm is 0.100889 = 629 rpm is 0.0686667 µm, and at x6 = 679 rp is 0.0663333 µm. the workpiece velocity is affected by 23.805 % on the surface roughness; decreasing x6 from 679 to 567 rpm leads to increase ra. the best value of workpiece velocity in this case is (567 rpm). fig. 11. the relationship between x6 7.8. the effect of magnetic poles velocity (x7) the relationship between magnetic poles workpiece velocity x7 with mrr y1 and surface roughness y2 shown in fig. 12. the mean value of y1 at x7 = 208 rpm is 0.00963333 g, at x7 = 347 rpm is 0.0494222 g, and at x7 = 496 rpm is 0.00856667 g. the magnetic poles velocity is affected by 9.748 % on the mrr; increasing x7 from 208 to 347 rpm leads to increase mrr, but increasing it from 347 t0 496 rpm leads to decrease mrr. the best value of magnetic poles velocity in this case is (347 rpm), while the mean value of y2 at x7 = 208 rpm is 0.0472222 x7 = 347 rpm is 0.0874444 µm, and at x7 = 496 rpm is 0.101222 µm. the magnetic poles velocity is affected by 7.431 % on the surface roughness; increasing x7 from 208 to 496 rpm leads to al-khwarizmi engineering journal, vol. 11, no. 8 ct of workpiece velocity (x6) relationship between workpiece velocity x6 with mrr y1 and surface roughness y2 shown . the mean value of y1 at x6 = 567 rpm is 0.00871111 g, at x6 = 629 rpm is 0.0104222 g, and at x6 = 679 rpm is 0.0484889 g. the by 5.199 % on the mrr; increasing x6 from 567 to 679 rpm leads to increase mrr. the best value of workpiece velocity in this case is (679 rpm), while the mean value of y2 at x6 = 567 rpm is 0.100889 µm, at x6 m, and at x6 = 679 rpm m. the workpiece velocity is affected by 23.805 % on the surface roughness; decreasing x6 from 679 to 567 rpm leads to increase ra. the best value of workpiece velocity the relationship between x6 and y1, y2. of magnetic poles velocity he relationship between magnetic poles workpiece velocity x7 with mrr y1 and surface . the mean value of y1 at x7 = 208 rpm is 0.00963333 g, at x7 = 347 rpm is 0.0494222 g, and at x7 = 496 rpm is 0.00856667 g. the magnetic poles velocity is affected by 9.748 % on the mrr; increasing x7 from 208 to 347 rpm leads to increase mrr, but asing it from 347 t0 496 rpm leads to decrease mrr. the best value of magnetic poles velocity in this case is (347 rpm), while the mean value of y2 at x7 = 208 rpm is 0.0472222 µm, at m, and at x7 = 496 agnetic poles velocity is affected by 7.431 % on the surface roughness; increasing x7 from 208 to 496 rpm leads to increase ra. the best value of magnetic poles velocity in this case is (496 rpm). fig. 12. the relationship between x7 7.9. the effect of finishing time (x8) the relationship between finishing time x8 with mrr y1 and surface roughness y2 fig. 13. the mean value of y1 at x8 = 30 sec is 0.0515556 g, at x8 = 45 sec is 0.00572222 g, and at x8 = 60 sec is 0.0103444 g. fin affected by 27.246 % on the mrr; decreasing x8 from 60 to 45 sec leads to decrease mrr, but decreasing it from 45 t0 30 sec leads to increasing mrr. the best value of finishing time in this case is (30 sec), while the mean value of y2 at x8 = 30 sec is 0.0752222 0.0817778 µm, and at x8 = 60 sec is 0.0788889 µm. finishing time is affected by 4.029 % on the surface roughness; increasing x8 from 30 to 45 sec leads to increase ra, but increasing it from 45 to 60 sec leads to decreasing ra. the best value of finishing time in this case is (45 sec). fig. 13. the relationship between x8 khwarizmi engineering journal, vol. 11, no. 3, p.p. 110 (2015) increase ra. the best value of magnetic poles velocity in this case is (496 rpm). between x7 and y1, y2. ct of finishing time (x8) he relationship between finishing time x8 with mrr y1 and surface roughness y2 shown in . the mean value of y1 at x8 = 30 sec is 0.0515556 g, at x8 = 45 sec is 0.00572222 g, and at x8 = 60 sec is 0.0103444 g. finishing time is affected by 27.246 % on the mrr; decreasing x8 from 60 to 45 sec leads to decrease mrr, but decreasing it from 45 t0 30 sec leads to increasing mrr. the best value of finishing time in this case is (30 sec), while the mean value of y2 x8 = 30 sec is 0.0752222 µm, at x8 = 45 sec is m, and at x8 = 60 sec is 0.0788889 m. finishing time is affected by 4.029 % on the surface roughness; increasing x8 from 30 to 45 sec leads to increase ra, but increasing it from eads to decreasing ra. the best value of finishing time in this case is (45 sec). fig. 13. the relationship between x8 and y1, y2. marwa k. qate’a al-khwarizmi engineering journal, vol. 11, no. 3, p.p. 110 (2015) 9 8. conclusions 1. analysis the regression model for surface roughness and mrr using anova show the effect of each parameter on the output as the below table: parameter ra % mrr % pole geometry x1 10.053 30.180 gap x2 16.133 18.126 grain size x3 7.088 1.156 doze x4 18.063 3.407 current x5 13.394 4.935 velocity of w.p x6 23.805 5.199 pole velocity x7 7.431 9.748 finishing time x8 4.029 27.246 2. the curves show that the decreasing of pole geometry angle to (-30) lead to increasing mrr. while the decreasing of workpiece velocity to (567 rpm) lead to increase ra. 9. references [1] f. yu. sakulevich,” magnetoabrasive machining “[in russian], nauka i tekhnika, minsk 1978. [2] n. k. jain, v. k. jain, and s. jha, ” parametric optimization of advanced fine finishing processes”, the international journal of advanced manufacturing technology, vol. 34, issue 11-12, pp 11911213, november 2007. [3] k. a. gogaev, 1 v. v. nepomnyashchii,1 t. v. mosina,1 i. p. neshpor,1 and m. leonowicz1, “special features of the magnetic abrasive machining”, refractories and industrial ceramics, vol. 47, no. 1, pp. 46-47, january 2006. [4] li bang-zhong, zhou jin-jin, “research on surface characteristics of non-traditional finishing”, journal of zhejiang university science, vol. 6, issue 10, pp.1152-1157, october 2005. [5] p. jayakumar, “semi magnetic abrasive machining”, 4th international conference on mechanical engineering, dhaka, bangladesh/pp. v 81-85, december 2001. [6] yahya m. hamad “improvement of surface roughness quality for stainless steel 420 plate using magnetic abrasive finishing method “,al-khwarizmi engineering journal, vol. 6, no. 4, pp. 10 – 20, 2010. [7] wang y., and hu d., “study on the inner surface finishing of tubing by magnetic abrasive finishing”, international journal of machine tools and manufacturing, vol.45, pp.43-49, 2005. [8] f. djavanroodi, “artificial neural network modeling of surface roughness in magnetic abrasive finishing process “, research journal of applied sciences, engineering and technology, vol. 6, no. 11, pp.1976-1983, 2013. [9] jae-seobkwak and tae-kyung kwak, “parameter optimization in magnetic abrasive polishing for magnesium plate”, institute of electrical and electronics engineers, vol.5, pp.544–547, january 2010. � ا����� � � �روة ��ظم ��ط� �� )2015( 110، ���� 3، ا���د11�ا���ارز�� ا� 10 � ���ا�#"2 و ���ل �ح ا. 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،:6?6\: ا3ekx03:، اn693ر، :v?7l ij?3ا :pexs fh\ rvit٢٣.٨٠ا % ngmv9u) >yb ،:6?6طn7k03ب اnj@~ا :\r; ،:6?6طn7k03ب اnj@~ا :uر، زاوn693ص، اehf3ق، اe`?0360: اi w6kx93ق، و و@/ اe`?03ت اnv6vb (a3اe93ا fh\ .ت وrgأظ ^�n9pا lb :6?6طn7k03ب اnj@~ا :uزاو �@n71 ار أن<`ptذج اe0p°٣٠ f3٣٠°ا f321دي ا .2دي اf3 زnuدة pexs: اuij?3) ٥٦٧ rpm(اf3 )٦٧٩ r? )rpm\: ا3ekx03:اn076l �@n713. زnuدة mb>ل إزا3: اe03اد <4d6963726f736f667420576f7264202d20cacdd3ede420e6dfd1ede320e6cec7e1cfc932322d3239> al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 14, no.2, june, (2018) p.p. 2229 die design of flexible multi-point forming process tahseen fadhel abaas * karem mohsenyounis ** khalida kadhim mansor *** *,**,*** department of production engineering and metallurgy / university of technology *email: tfalani@yahoo.com **email: karim_mohsen @yahoo.com ***email: kh_ak07@ yahoo.com (received 30 july 2017; accepted 26 december 2017) https://doi.org/10.22153/kej.2018.12.002 abstract multi-point forming (mpf) is an advanced flexible manufacture technology, and the technology results from the idea that the whole die is separated into small punches that can be adjusted height. this idea is applied to the traditional rigid blank-holder, so flexible blank-holder (fbh) idea can be obtained. in this work, the performance of a multi-point die is investigated with pins in square matrix and suitable blank holder. each pin in the punch holder can be a significant moved according to the die high and at different load that applied with spring with respect to spring stiffness. the results shows the reduction in setting time with respect to traditional single point incremental forming process that lead to (90%). and also show during the forming process, the deformation of the interpolator can induce a shape error in the formed work-piece and the blank holder can reduce/eliminate dimples that sometimes arise in the work-piece. the minimum force applied using multi-point die is 28.556kn, while the load when complete the forming process is 30.8kn that caused displacement of die to 32.8mm. keywords: flexible manufacturing, multi-point forming, die design, cad and three-dimensional surface. 1. introduction the application of sheet metal forming in aerospace, automotive, medical, and recently in renewable energy is widely used. the traditional sheet metal forming processes like the deep drawing and stamping are more adjustable to continue production, customized products, small batch and high value-added, the employment of traditional process would results long lead time, high-energy consumption, and high tooling costs. to release these limitations, the flexible sheet metal forming process concept that aimed to reduce energy consumption, incurred cost, the lead time, and has attracted significant research attentions in recent years, multi-point forming (mpf) and incremental sheet forming (isf) are two typical flexible sheet metal forming approaches[1]. in this process method a pins matrix that arrangement approximates to continuous active surfaces of a traditional die. each pin is vertically aligned according to the part geometry in matrix form; figure (1) illustrated the multi-point process [2]. in this context, controlling the height of each pin is one of the main technological problems which assures the geometry of the part and avoids in general the dimpling phenomenon when rubber multi-point forming (rmpf) without interpolator is applied. the network of small dimples affects the surface quality, mainly if such types of parts are used in automotive and aeronautical industry for exterior parts or in medicine [3]. there are many researchers who have designed die in this field but with fixed die according to the product form and there is no researcher dealing with flexible die design: tahseen fadhel abaas al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 2229 (2018) 23 pham et al (2008) introduces a rapid and flexible tooling for manufacturing 3d panels using multipoint forming (mpf) methodology. mpf technology employs adjustable element matrices and each element in matrix can be controlled to adjust its coordinates for shaping a discrete 3d tooling surface [5]. b. lu et al (2014) illustrated a developed flexible sheet metal forming concept with reduced time of forming with respect to the traditional incremental sheet metal forming process and better thickness distribution in final product. in this work, a twostep forming process has been introduced: multipoint forming as pre-forming process is applied to achieve the initial shape with the required thickness distribution. after the preforming process, used the incremental sheet metal forming process is to finalize the geometry of product with the required thickness distribution [1]. hani aziz et al (2016) focused on simulation of multi-point die to produce the dish uses bezier function for surface modeling to get the best modeling points for dish. the mathematical functions required to generate curves and surfaces are investigated together with complete algorithms using matlap program for their achievement [6]. mohamed abosaf et al (2017) presented the effect of process parameters, like the coefficient of friction, radius of curvature, size of pin, and elastic cushion thickness, on the formed surface quality in a flexible multipoint forming die. the aim of this research was to find the optimization of process variables used in multi-point forming process [7]. fig. 1. comparison of multipoint forming: (a) forming die; (b) multipoint forming process. [4] 2. design of multi-point forming die the shape of multipoint forming die must be adjusting; it should be first determine the location of each punch element, then move the punch in zaxis to form the required surface. while the x and y coordinate of all punches are stationary. based on the tangent principle between the required surface and punch surface, the z coordinate of each punch can be got. figure (2) presents the punch contact with respect to forming plate. the function of objective surface is f(x,y), the spherical radius of punch is (rp), the central coordinate of punch is (xp,yp,zp), the function of punch surface is: [8, 9] φ � ��r�� � x � x��� � y � y��� z� …(1) fig. 2. determination of element position. [8] in this work, the developed method used to automate the adjusting of each punch with respect to fixed die surface, the punch moved by using spring mechanism, the spring mechanism control the displacement and the load applied for each punch with respect to fixed surface (die). figure (3) presents the multi-point forming die. tahseen fadhel abaas al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 2229 (2018) 24 fig. 3. multi-point forming die. 2.1. design calculations the die consists of a matrix of punch that moves inside springs that illustrated in figure (4). each spring when moved along (z-axis) applied the load that increase with respect to punch movement, the most important factor that effect on spring design is stiffness. and to find the appropriate spring to applied force that cause the forming of the plate can be find as following: � � � � ��� …(2) where: a: the maximum contact area between spherical punch and forming plate d:maximum diameter that contact the forming plate (=diameter of punch/2). fig. 4. schematic the multi-point forming die (without load, and after applying the load when finishing forming process). in this work, the diameter of punch is selected (d=15mm), the maximum diameter contact to the forming plate equal to the radius of the punch at the edge of the die as illustrated in figure (5). so, using equation (2) to find the area of punch: � � � 4 15/2�� � 44.156��� fig. 5. the maximum contact area between the bunch and the forming plate. tahseen fadhel abaas al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 2229 (2018) 25 and to find the maximum force and displacement that applied on forming punch using the compression test result of selected spring was illustrated in figure (6). from load-deformation curve above, the maximum load applied in spring is (236 n) (y-axis) caused maximum displacement (44mm) (x-axis). � � � � � �� ��.!" � 5.344 %/��� …(3) & � ' ∗ ) …(4) ' � & ) � 236 44 � 5.36%/�� where: f: maximum force applied on spring k: spring stiffness δ: maximum displacement of spring and when using the matrix of punch (11*11=121 punch), the maximum force applied to forming the plate is: f=236*121 = 28556n =28.556kn through the value of the spring stiffness was calculated, the kind of spring can be chosen in which the metal could be formed, as well as through the calculations it is clear that the minimum force that can be applied using the current forming die design is 28.556 kn, with addition to friction force between springs and guides that not exiting to 10%. fig. 6. load-deformation test result. 3. design process the experimental work can be descripting briefly in the following steps: 4.1 design the square punch shape (15mm) and (77.5mm) in length with spherical forming end with radius (7.5mm), with an internal tooth diameter of 8 mm and depth of 40 mm. the process of manufacturing was done on a turning machine and with four jaw chuck and the manufacture of a curving mold with a (9.5 mm) radius of arc as shown in figure (7). 4.2 design the spring that applied the force with (80mm length and 13mm diameter). spring type is selected as indicated by its calculations above. fig. 7. dimension of punch that used in this work. 4.3 design and manufacturing the upper plate for die with matrix (11*11) with (0.1mm) clearance using cnc milling machine that illustrated in figure (8-a), this plate used to fixed the punches as shown in figure (8-b). 4.4 design and manufacturing the lower plate and guides with (diameter =26mm and length 260 mm) as shown in figure (8-c&d). 4.5 manufacturing the punches and its guides. 4.6 assembly the final die. tahseen fadhel abaas al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 2229 (2018) 26 4.7 manufacturing the part that need to forming using bezier surface and machine in cnc milling machine. 4.8 forming the plate using the developed die that illustrated in figure (9). (a) (b) (c) (d) fig. 8. stages of die manufacturing, (a,b) upper plate ,(c) lower plate and guides and (d) forming die after assembly upper plate, lower plate and guides. (a) (b) (c) (d) fig. 9. cad-design and the product manufacturing using multi-point forming die (a) cad-design (b) forming die (c) final product without blank holder (d) final product using blank holder. tahseen fadhel abaas al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 2229 (2018) 27 4. results and discussion in multi-point forming process, the load is gradually increased smoothly to 14.45kn, which corresponds to 8.25 mm of the upper die displacement. at this point, all pins were in contact to the forming plate and plastic deformation started to take place. after that, the force rapidly increased with plastic deformation due to strain hardening of the material [7]. the maximum force that taken from chart of (loaddeform) is about 30.8kn when the upper and lower dies are closed at forming depth 32.8mm; figure (10) presented the forming load and displacement in this process. the advantage of this method is lower forming time with respect to incremental forming process, because the forming time depending on the speed of load applied, in this work, the speed used is 10mm/min and by moving to maximum displacement (32.8mm) the total time required to complete this process is 3.2 min, while the average forming time required to forming this shape using incremental forming process is (2035) min depending on feed rate [10]. so the reduction of process time exists to 90%. fig. 10. forming load-displacement chart result in multi-point forming process. 5. conclusions this work proposed a new design of multipoint forming die to control the displacement and force that applied on each punch to increase the flexibility of forming process and reduce adjusting time required for each product, this study demonstrated the following: 1. multi-point sheet metal forming is good method for flexible forming but have the limitation one of them is adjusting time and dimension accuracy that required a high skill technical to achieve this sitting. 2. using the sliding punch that control of the displacement and load applied from each punch on forming product give a good result with reduce of setting time more than 90%. 3. blank holder in multi-point process is very important to reduce the wrinkling in the final product and distribute the force on the blank. 4. one of the limitations of this process is a dimple on final product that must be treatment. 6. references [1] b. lu, h. zhang, d.k. xu and j. chen, a hybrid flexible sheet forming approach towards uniform thickness distribution, international conference on manufacture of lightweight components – manulight2014. [2] viorel paunoiu and virgil teodor, geometric reconfiguration of the multipoint forming dies using reverse engineering, the annals of “dunărea de jos” university of galati fascicle, technologies in machine building issn 12214566, 2009. [3] a a tolipov, a elghawail, m abosaf, s shushing, d pham and k essa, experimental research and numerical optimisation of multipoint sheet metal forming implementation using a solid elastic cushion system, school of engineering, university of birmingham, conference paper · july 2017 tahseen fadhel abaas al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 2229 (2018) 28 [4] mingzhe li, yuhong liu, shizong su, guandgquan li, multi-point forming: a flexible manufacturing method for a 3-d surface sheet, jilin university of technology, changchun 130025, people’s republic of china.1997 [5] d.t. pham, s.z. su1, m.z. li , c.g. liu , f. carrai, f. massabe , a.m.yan and m. vinay, flxible tooling for manufacturing 3d panels using multi-point forming methodlogy, manufacturing engineering centre, cardiff university, cardiff, united kingdom, conference paper june 2008 [6] hani aziz ameen, haidar akram alsabti and zahraa abdul kareem radhi, finite element analysis of the dish multi-point forming process , international journal of engineering research & technology (ijert), vol. 5 issue 07, july-2016. [7] mohamed abosaf, khamis essa, ali alghawail, abror tolipov, shizhong su and duc pham, optimisation of multi-point forming process parameters, int j adv manuf technol, 2017. [8] heli peng, mingzhe li, chunguo liu and junhui cao, study of multi-point forming for polycarbonate sheet, int j adv manuf technol, 67:2811–2817, 2013. [9] se yun hwang, jang hyun lee, yong sik yang and mi ji yoo, springback adjustment for multi-point forming of thick plates in shipbuilding, elsevier journal, computeraided design 42, 1001-1012, 2010. [10] q. mohamed doss, tahseen fadhel abaas and aqeel sabree bedan, the effect of tool path strategy on twist behavior in single point incremental sheet metal forming, journal of engineering, baghdad university, vol. 4, 2013. )2018( 22-29، صفحة 2د، العد14دجلة الخوارزمي الهندسية المجلم تحسين فاضل عباس 29 وتنفيذ قالب مرن لعملية التشكيل المتعدد النقاط تصميم ***كاظم منصور ةخالد ** كريم محسن يونس *تحسين فاضل عباس ن/ الجامعة التكنولوجيةقسم هندسة االنتاج والمعاد*،**،*** tfalani@yahoo.com البريد االلكتروني:* karim_mohsen @yahoo.com:البريد االلكتروني** kh_ak07@ yahoo.com:البريد االلكتروني*** ةالخالص ددع الى القالب تقسيم رةفك من ناتجة التقنية هذه ان حيث المتقدمة المرنة التصنيع عميات من النقاط متعدد التشكيل عملية تعد الى وصوال المصفوفة في موقعها حسب عدة كل بابعاد التحكم ويتم متناسقة مصفوفة بصورة تترتب والتي الصغيرة العدد من العملية اتمتغير يناسب بحيث وتصنيعه تصميمه تم حيث التشكيل عملية اثناء للعينة ماسك اضافة تم حيث. المطلوب الشكل .الحالية السبرنك ميكانيكية لىع باالعتماد القوة تسليط تم حيث مربعة مصفوفة بشكل المرتبة العدد هذه اداء مناقشة تم البحث هذا في ممالمص للقالب نسبة عدةال موقع على وباالعتماد المطلوبة االزاحة وفق على السبرنك جساءة على باالعتماد القوة بتسليط تقوم التي الى نسبة) %٩٠( ةبنسب لالعداد الالزم الزمن تقليل طريق عن ةالعملي محددات بعض على التغلب تم حيث انتاجه المطلوب والشكل على عدةال ضغط من الناتج راالث وتقليل للمنتج النهائية باالبعاد الحاصل الخطا تقليل الى باالضافة التزايدي النقطي التشكيل عملية التشكيل عملية من ناتجةال القوة بينما) كيلونيوتن ٢٨٫٥٥٦( هي التشكيل بدء عند القالب يسلطها التي المحسوبة القوة ان. النموذج ).كيلونيوتن٣٠٫٨( هي) ملم٣٢٫٨( بعمق النموذج تشكيل عند العملية (microsoft word \314\346\307\317 \346\336\315\330\307\344100111) al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 14, no. 3, september, (2018) p.p. 100111 studying the mechanical properties of denture base materials fabricated from polymer composite materials jawad kadhim oleiwi* qahtan adnan hamad** *,**department of materials engineering / university of technology *email: jawadkad@yahoo.com **email: qah84@yahoo.com (received 22 august 2017; accepted 10 january 2018) https://doi.org/10.22153/kej.2018.01.006 abstract in this research, the effect of adding two different types of reinforcing particles was investigated, which included: nano-zirconia (nano-zro2) particles and micro-lignin particles that were added with different volume fractions of 0.5%, 1%, 1.5% and 2% on the mechanical properties of polymer composite materials. they were prepared in this research, as a complete prosthesis and partial denture base materials was prepared, by using cold cure poly methyl methacrylate (pmma) resin matrix. the composite specimens in this research consist of two groups according to the types of reinforced particles, were prepared by using casting methods, type (hand lay-up) method. the first group consists of pmma resin reinforced by (nano-zro2) particles, while the second group consists of pmma resin reinforced by (micro-lignin) particles. the mechanical tests performed in this research includedtensile test, compression test, impact test and hardness test. the results of this study showed that the values of tensile modulus of elasticity, compressive strength and hardness properties increased with increasing the volume fraction of these particles in pmma composite materials. while, the values of tensile strength, elongation and impact strength properties decreased. also, the addition of (nano-zro2) particles showed greater effect than that of (micro-lignin) particles in some properties of pmma composite materials for prosthesis denture base materials specimens, while they have lower effect for the other properties. keywords: compression test, lignin, nano-zro2, hardness test, impact test, particles, pmma, tensile test. 1. introduction many biomaterials are available in medicine and dentistry fields, which can be classified as metals, polymers, ceramics and composites materials, with all have advantages and drawbacks and they are developed to be used for bone and tooth problems. polymers have low mechanical strength compared to bone and tooth. metals have superior mechanical properties wear resistance and biocompatibility, but they are very corrosive. ceramics are brittle and have low fracture toughness. all these properties of polymers, ceramics and metals are considered and combination to produce the composite materials. although the polymer material using in dentistry fields, but polymer composites materials are available in a wide variety of compositions and properties, which make them suitable for several orthopedic and dentistry applications such as (dental implantation and denture base materials), because they have good properties such as good elastic modulus, high strength, low creep and high heat deflection as compared to polymer materials [1]. the composite materials have many important properties which make them suitable for many dentistry uses, therefore many researches done for bone, denture base and tooth substitute as composite materials composed of different particles and a polymer matrix [2]. acrylic resins have been the most widely used and accepted among all denture base materials, and it was estimated that they represent (95%) of jawad kadhim oleiwi al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 100111 (2018) 101 the polymer materials in dentistry application as denture base materials, that usually consist of poly methyl methacrylate which is a thermoplastic polymer [3]. the first using of poly (methyl methacrylate) (pmma) during the (1930), was used in dental prosthetics. in (1936) introduced (pmma) as heat cure denture base material, when this material was molded to desired shape under heat and pressure, which became the major polymer to be used in last years as denture base material. the first using of (pmma) as cold cure denture base material was in (1938). furthermore, other thermoplastic polymers used as denture base materials from 1960 as alternative of (pmma), but they have not been shown to produce denture of greater accuracy, better performance and have not been proved to be superior to (pmma). a result the (pmma) resin remains the materials of choice for denture base material [4]. prosthetic dentistry is the replacement of missing teeth, which may have been lost for a variety of reasons, with either fixed or removable dentures, that using depending upon a many factors of these replacements. a partial denture are made to replace one or more of lost teeth and they have the advantage that support and retention can be derived from adjacent retained natural teeth and using design features such as occlusal rests and clasps. while, the complete denture replaces all the teeth in one dental arch, the objectives of these treatment they would be have good speech, good appearance, effective chewing and biting, comfort and the ability to engage in various social and interpersonal activities [3]. 2. aim of this study in this research, done several attempts to develop the poly methyl methacrylate (pmma) that is used for upper or lower complete and partial denture base material with having desirable properties, by using the new type of cold cured pmma resin to withstand against any denture fracture, and avoid or reduce the breakage of denture base material, by reinforcing pmma with different type of particles (nano-zirconia and micro-lignin) with selected volume fractions, to product (nano to micro) composite materials for prosthetic dentures, and study the mechanical properties (tensile, compression, impact and hardness) of these materials. 3. theoretical part 3.1 techniques of polymerization denture base materials according to mode of chemical reaction to free radical generation, various methods were used for curing acrylic resin. they are classified as heat curing, cold (self) curing and light curing. the cold polymerizing denture base materials are chemically similar to the heat cured denture base, varying only in the manner in which polymerization method. the polymerization reaction is accelerated by chemical activation, rather than by heat, by added catalyst to the monomer, such as (dimethyl-para-toluidine). this catalyst leads to color stability property of chemically activated resins. also the reducing agent adding to produce sufficient free radicals, which promote initiate the polymerization of the monomer in the denture base material at room temperature, therefore called cold curing [3]. 3.2 common causes of dentures fracture one of the most serious complications with complete or partial prosthetic dentures is fracture, many studies on prosthetic denture were showed that the most common problem is fracture of dentures, in a survey reported on greater number of partial and complete dentures, show results about (63% to 68%) of dentures had broken within few years after fabrication in denture base materials [5]. there are several reasons for denture fracture, the denture fracture caused primarily by impact failure or by fatigue failure. in addition, wear and tear failures over time, by the temperature variations that found in hot and cold foods and drinks, as well as certain types of acidic foods and the moisture in your mouth can wear down a denture. also many causes for the denture fraction, it was found such as: stress concentration (a large notch and thin denture), poorly fitting denture, lack of fitness denture, lack of balanced occlusion, porosity, bone loss can shrink the jaw. if your denture does not fit properly, it may move around in the mouth, and this lack of stability can cause stress and pressure points that lead to increased denture deformation which finally can cause crack or break denture, for these reasons trying to reinforce the pmma matrix is to reduce these fracture problems [5]. jawad kadhim oleiwi al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 100111 (2018) 102 3.3 types of fracture the principle difference between the modes of fracture is the rate at which the stress is applied and relation to the ability of the polymer chain to distort at minimizes of stress concentration [6]. 3.3.1 impact fracture this type of fracture usually happens when patients are coughing which pushes the denture out of the mouth or accidental dropping of the denture over the hard floor or sink, also it may occur if the patient is involved in a violent accident. figure (1) shows the images of impact fracture that occur in prosthetic denture [6]. fig. 1. show the impact fracture in the prosthetic dentures. 3.3.2 fatigue fracture the fatigue failure occurs when the denture deforms repeatedly through the mastication process by small forces (occlusal forces) at this loading cycle that exceeds the mechanical capacity of denture base material. figure (2) shows the images of fatigue fracture that occur in prosthetic denture [6]. fig. 2. show the fatigue fracture in the prosthetic dentures. 4. experimental part 4.1 poly (methyl methacrylate) (pmma) acrylic resin the matrix material that used in this research included cold curing poly methyl methacrylate (pmma) as denture base materials, to preparation of test specimens for pmma composite prosthetic dentures. pmma is a linear thermoplastic polymer, the chains are thinner, smoother and slide past each other easily, finally material becomes softer, therefor can be fabrication and processed easily by (hand lay-up) methods. cut surfaces of pmma acrylics resin may be readily finished by polished by tipped tools. this type of polymer materials distinguishes by many properties compared with other type of polymer such as: high strength, high modulus of elasticity, low elongation at break and good dimensional stability, but it has low impact strength and low fatigue strength. also, pmma resin is favored for its good physical properties such as the color which can like the human’s internal skin with the pinkish color, low moisture, low water absorbing and high glass transition temperature [7]. some mechanical and physical properties of (pmma) resin that used in this study are shown in table (1). jawad kadhim oleiwi al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 100111 (2018) 103 table 1, some mechanical and physical properties of pmma resin. tensile strength (mpa) young's modulus (gpa) impact strength (kj/m2) flexural strength (mpa) density (g/cm3 ) 47 ‐ 79 2.2 ‐ 3.8 1.2 – 20 3 ‐ 3.5 1.19 the cold cured was used to prepare the test specimens of the pmma composite prosthetic dentures, consist of polymer powder and monomer liquid (methyl methacrylate, mma). the standard proportion in mixing ratio is usually for cold cure acrylic resin of (15 g) polymer powder (pmma) and (10 ml) monomer liquid (mma) (1.5 g / 0.95g) by weight according to the manufacturer's instructions of manufacturer company. where the mixture was mixed of liquid (mma) in the clean and dry container (glass beaker), follow after that by slow addition of dry powder (pmma) with or without particulate reinforces materials (nano-zro2 or micro-lignin) to liquid (mma), the mixture was stirred at room temperature continuously by using mechanical mixing (brabender mixer) at speed (20 r.p.m.) until reached to the dough stage, this mixer is shown in figure (3), then poured with thin straight line in the center of opening mould with maximum time about (4.5 min) according to manufacture company. during mixture pouring in the glass mould, the mould must be vibrated from side to side to remove any gas bubbles from the specimens, and reminder of the mixture was poured into mould hole until the glass mould filling. this mixture was covered in closed container and left to stand on the bench top at room temperature for (8-13) min from beginning of mixing process as working time to increase the viscosity of mixture and surface of the pouring has become hard and matt. fig. 3. mechanical mixer (brabender mixer). 4.2 particles reinforcing materials two types of particles were used in this study as reinforces materials with percentage of (0.5, 1, 1.5 and 2) vol %, that added to the polymer powder (acrylic powder) include the following: 4.2.1 micro-lignin (pumpkin) particles. there is a family of plants called the family of the qur'aa and within this family squash, pumpkin and others. they have multiple shapes including spherical and linear. the pumpkin is generally multicolored, orange, yellow and green, which has been used in this study [8]. the pumpkin contains 95% water, the fruits of pumpkin are anti-oxidants, anti-infections, antibacteria, cancer and diabetes diseases because it contains of many basic nutrients needed the body to perform various functions, such as vitamin (a), anti-oxidation and metal materials (iron, magnesium, potassium, zinc, calcium and phosphorus). it also protects the mouth from the inside specifically of the various infections and slough that affect it, in addition activates gums and fights toothache. as well as to maintain the health of the skin and body, help to strengthen the immune system of the body and prevent the oxidation of cholesterol [8]. the particle size and particle size distribution of (micro-lignin) particles were carried out in atomic force microscopy (afm) in baghdad university laboratories by using scanning probe jawad kadhim oleiwi al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 100111 (2018) 104 microscopy (spm). the result of particle size distribution of micro-lignin (pumpkin) particles structures in (2-d) and (3-d) as shown in figure (4), and the average value of diameter was (136.05 nm). a b fig. 4. (a) shows 2-dimensions and (b) shows 3 dimensions of ((micro-lignin) particles by afm test. 4.2.2 nano-zirconium oxide (zro2) particles zirconium oxide (zirconia) is one of most important of bio-ceramics oxides, has shiny graywhite color and it is not available in nature as a pure oxide. the zirconia has important properties such as high fracture toughness, high tensile strength, high hardness, low modulus of elasticity, high flexural strength, high density, high thermal shock resistivity and thermal expansion similar to cast iron, high wear and corrosion resistance in acids and alkalis, also little chemical change during long term exposure to body fluid. therefore, the zirconia using for many biomedical application, and introduced to solve the problem of alumina brittleness and the consequent potential failure of implants because it is exhibits the best mechanical properties, creating tougher prostheses [9]. the particle size and particle size distribution of (nano-zro2) particles were carried out in atomic force microscopy (afm) in baghdad university laboratories by using scanning probe microscopy (spm). the result of particle size distribution of (nano-zro2) particles structures in (2-d) and (3-d) as shown in figure (5), and the average value of diameter was (87.06 nm). some mechanical and physical properties of (zro2) that used in this study are shown in table (2). -a -b fig. 5. (a) shows 2-dimensions and (b) shows 3 dimensions of (nano-zro2) particles by afm test. table 2, some mechanical and physical properties of (zro2) particles. 4.3 mechanical tests the mechanical tests were performed in this study to evaluate some mechanical properties of the pmma composite materials for the prosthetic denture base include: tensile strength (mpa) young's modulus (gpa) compression strength (mpa) flexural strength (mpa) density (g/cm3 ) 8001500 205-210 2000 9001200 5.7-6.1 jawad kadhim oleiwi al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 100111 (2018) 105 4.3.1 tensile test the tensile test is performed according to (astm d638-03) by using tensile machine (universal testing machine), type (instron) at a cross head speed (strain rate) of (5mm/min) and load was applied equal to (5 kn) until break the specimen occur. figure (6) shows the standard specimen of tensile test. the test process involves placing the test specimen in the testing machine and slowly extending it until it fractures. during this process, the elongation of the gauge section is recorded against the applied force. the elongation measurement is used to calculate the engineering strain. the tensile force is used to calculate the engineering stress by divided on normal crosssection area of the specimen. final obtain the (stress–strain) curve [10]. fig. 6. schematic specimen for standard specimen of tensile test. 4.3.2 compression test compressive strength is the stress required to rupture a specimen i.e. (the amount of resistance to fracture under compression load). compression failure in composite material depended up on the properties of matrix such as toughness, properties of reinforced such as volume fraction and interface. the compression test is performed according to (astm d695) by using the same tensile machine (universal testing machine), type (instron) at across head (strain rate) of (5mm/min) and applied load was (25 kn) on the specimen’s. figure (7) shows the standard specimen of compression test. the compression tester similar to tensile tester, done by applying compressive load on the specimen’s top and bottom at the same time until fracture of the specimen occur, five times were tested for each specimen and take the averaged for the final result of five specimens it was tested [11]. fig. 7. schematic specimen for standard specimenof compression test. 4.3.3 impact test an impact test is used to observe the behaviors of material will exhibit when it expose to shock loading that lead to deformation, then fracture of specimen. by determine the ability of the material to absorb energy during a collision. this energy may be used to determine the toughness, impact strength, fracture resistance, impact fracture resistance of the material. izod impact that is used in this research is defined as the kinetic energy needed to initiate fracture and continue the fracture until the specimen is broken. to perform this test the sample is placed into a holding in the device with the geometry according to (iso-180) by using izod impact testing machine type is (xju series pendulum izod/charpy impact testing machine), figure (8) shows the standard specimen of impact test [12]. fig. 8. schematic specimen for standard specimen of impact test. in this type of impact test the specimen clamped at one end and held vertically cantilevered beam and it's broken by (5.5j) pendulum, at impact energy of (5.5j) and velocity (3.5 m/s). then release the pendulum from a known height so that it collides with the impact specimen as sudden force, then record amount of energy that required to fracture this specimen, five times were tested for each specimen and take the averaged for the final result of five specimens it jawad kadhim oleiwi al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 100111 (2018) 106 was tested, the average impact energy of these specimens as shown in in table (3) [12]. table 3, impact energy of pmma composite reinforced by different concentration of (nano-zro2 or microlignin) particles. specimen names average impact energy (j) pmma 26.6 pmma + 0.5 % nano-zro2 22.9 pmma + 1 % nano-zro2 19.5 pmma + 1.5 % nano-zro2 13.31 pmma + 2 % nano-zro2 11.56 pmma + 0.5 % microlignin 25.9 pmma + 1 % microlignin 23 pmma + 1.5 % microlignin 21.64 pmma + 2 % microlignin 17.44 4.3.4 hardness test hardness is the characteristic of a solid material expressing surface resistance to scratching, cutting, wear, indentation, penetration and workability from an applied force of sharp point and as indication of surface durability. durometer hardness test is one of several methods that using to measures of the hardness in polymers and rubbers materials, there are several scales of durometer are used for materials with different properties. in this research the hardness test is performed by using dorumeter hardness device, type (shore-d) scales according to (astm d2240), and standard specimen for hardness test as shown in figure (9). the specimen place under the indenter area at load applied equal to (50 n) and depressing time of measuring equal to (15sec), each scale results in a value between (0 to 100) hardness numbers, with higher values indicating a harder material [13]. the surface of specimens must be smooth in zone test. hardness value is very sensitive to the (specimen thickness, specimen diameter and distance from the edge more than 12 mm). therefore, the minimum thickness of the specimen is (3 mm) with diameter more than (30mm). each specimen was tested seven times at different position of each specimen at same time must be tested in the middle, not on the edge of the specimen, and average value was taken [13]. fig. 9. schematic specimen for standard specimen of hardness test. according to (ada specification no.12, 1999), all these tests specimens after complete finishing and polishing processes must be stored in distilled water at (37 1) ºc for (48 hr), in order to remove any residual monomer and release residual stress, also to ensure that the denture base materials remains in semi oral environment. then, each test were carried out in air at room temperature (23 2) ºc. five specimens where used for most tests and final results represent the average for five specimens it was tested [14]. figure (10) shows the solidified composite prosthetic dentures test specimens after remove from glass mould and before testing process. fig. 10. shows the composites prosthetic dentures specimens for pure pmma and pmma composite reinforced by (micro-lignin or nano-zro2) particles. jawad kadhim oleiwi al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 100111 (2018) 107 5. results and discussion 5.1 results and discussion of tensile test for modified composites the tensile strength values results that obtained from tensile test that carried out on pmma composite specimens for prosthetic denture base materials that prepared in this research are shown in the chart (1), which show the effect of adding both types of the particles which include (nanozro2 and micro-lignin) with different volume fractions on the tensile strength of pmma composite. from this chart can be noticed how the tensile strength values decreased with the increasing of the volume fraction of these particles in both groups of pmma composite materials. this is due to the low strengthening and weak bond, and those particles cannot reduce the slipping of the pmma chains [15 and 16]. it can also be noticed that the addition of micro-lignin particles has a noticeable effect on the tensile strength of pmma composite specimens more than nano-zro2 particles, therefore, tensile strength for (pmma–microlignin) composite specimens is lower than values of tensile strength for (pmma–nano-zro2) composite specimens. thus, the tensile strength value decreased from (51.7 mpa) for pmma specimen (as referenced) to reach to the lower value of (22 mpa) for composite materials (pmma–2% micro-lignin). while the tensile modulus of elasticity values results that obtained from tensile test that carried out on pmma composite specimens for prosthetic denture base materials that prepared in this research are shown in the chart (2), which show the effect of adding both types of the particles which include (nano-zro2 and micro-lignin) with different volume fractions on the tensile modulus of elasticity of pmma composite. chart 1. shows tensile strength data of pmma composite denture base materials as function of (nano-zro2 or micro-lignin) particles content in composite. from this chart can be noticed how the tensile modulus of elasticity values increased with the increasing of the volume fraction of these particles in both groups of pmma composite materials. this is due to the strengthening mechanism which meaning (those particles reduced the slippage of the pmma chains by filling the spaces inside the pmma matrix and created full interface, formation high bonding strength between particles and pmma matrix). furthermore, high modulus of elasticity of these particles as compared to pmma resin [15 and 16]. it can also be noticed that the addition of micro-lignin particles has a noticeable effect on the tensile modulus of elasticity of pmma composite specimens more than nano-zro2 particles, therefore, the tensile modulus of elasticity for (pmma–micro-lignin) composite specimens is higher than the values of tensile modulus of elasticity for (pmma– nano-zro2) composite specimens. thus, the tensile modulus of elasticity value increased from (7.5 gpa) for pmma specimen (as referenced) to reach to the higher value of (13.95 gpa) for composite materials (pmma–2% micro-lignin). chart 2. shows tensile modulus of elasticity data of pmma composite denture base materials as function of (nano-zro2 or micro-lignin) particles content in composite. but the elongation percentage values results that obtained from tensile test that carried out on pmma composite specimens for prosthetic denture base materials that prepared in this research are shown in the chart (3), which show the effect of adding both types of the particles which include (nano-zro2 and micro-lignin) with different volume fractions on the elongation percentage of pmma composite. from this chart can be noticed how the elongation percentage values decreased with the increasing of the volume fraction of these particles in both groups jawad kadhim oleiwi al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 100111 (2018) 108 of pmma composite materials. this is due to the increasing in the particles number will be act as localized stress concentration regions, that lead to decreased the elongation percentage [15 and 16]. it can also be noticed that the addition of nanozro2 particles has a noticeable effect on the elongation percentage of pmma composite specimens more than micro-lignin particles, therefore, elongation for (pmma– nano-zro2) composite specimens is lower than values of elongation percentage for (pmma– micro-lignin) composite specimens. thus, the elongation percentage value decreased from (6.3 %) for pmma specimen (as referenced) to reach to the lower value of (1.9 %) for composite materials (pmma–2% nano-zro2). chart 3. shows elongation data of pmma composite denture base materials as function of (nano-zro2 or micro-lignin) particles content in composite. 5.2 results and discussion of compression test for modified composites the compressive strength values results that obtained from compression test that carried out on pmma composite specimens for prosthetic denture base materials that prepared in this research are shown in the chart (4), which shows the effect of adding both types of the particles which include (nano-zro2 and micro-lignin) with different volume fractions on the compressive strength of pmma composite. from this chart it can be noticed how the compressive strength values increased with the increasing of the volume fraction of these particles in both groups of pmma composite materials. this is due to the strengthening mechanisms which meaning the particles reduced the slippage of the pmma chains by filling the spaces inside the pmma matrix and it can also be related to the higher compressive strength of these particles as compared to pmma resin [16 and 17]. it can also be noticed that the addition of nanozro2 particles has a noticeable effect on the compressive strength more than micro-lignin particles, therefore, compressive strength for (pmma–nano-zro2) composite specimens is higher than the values of compressive strength for (pmma–micro-lignin) composite specimens. this is due to the improvement of the mechanical properties of zro2 particles and the nature of zro2 particles which has high compressive strength as shown in table (2). thus, the compressive strength value increased from (176.5 mpa) for pmma specimen (as referenced) to reach to the higher value of (360.3 mpa) for composite materials (pmma–2% nano-zro2). chart 4. shows compressive strength data of pmma composite denture base materials as function of (nano-zro2 or micro-lignin) particles content in composite. 5.3 results and discussion of impact test for modified composites the impact strength values results that obtained from impact test that carried out on pmma composite specimens for prosthetic denture base materials that prepared in this research are shown in the chart (5), which shows the effect of adding both types of the particles which include (nano-zro2 and micro-lignin) with different volume fractions on the impact strength of pmma composite. from this chart can be noticed how the impact strength values decreased with the increasing of the volume fraction of these particles in both groups of pmma composite materials, because of any increasing in these particles numbers, it will be act as points for localized stress concentration regions from which the failure will begin. furthermore, the natural of these particles is brittleness and weakness in the jawad kadhim oleiwi al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 100111 (2018) 109 ability of resistance to impact loads comparing with pmma resin [16 and 18]. it can also be noticed that the addition of nano-zro2 particles has a noticeable effect on the impact strength of pmma composite more than micro-lignin particles, therefore, impact strength for (pmma– nano-zro2) composite specimens is lower than the values of compressive strength for (pmma– micro-lignin) composite specimens. this is due to aggregated of (nano-zro2) particles which have high surface energy. thus, the impact strength value decreased from (6.65 kj/m2) for pmma to reach to the lower value of (2.89 kj/m2) for composite materials (pmma–2% nano-zro2). chart 5. shows impact strength data of pmma composite denture base materials as function of (nano-zro2 or micro-lignin) particles content in composite. 5.4 results and discussion of hardness test for modified composites the hardness (shore-d) values results that obtained from hardness test that carried out on pmma composite specimens for prosthetic denture base materials that prepared in this research are shown in the chart (6), which shows the effect of adding both types of the particles which include (nano-zro2 and micro-lignin) with different volume fractions on the hardness (shored) of pmma composite. from this chart can be noticed how the hardness values increased with the increasing of the volume fraction of these particles in both groups of pmma composite materials. this is due to the high hardness and brittleness of these particles as compared to pmma resin alone, furthermore, related to the wettability and the bonding strength between the pmma matrix and these particles, to make the harder surface by restricting the movement of the pmma chains towards the stress that is applied on it [16 and 19]. it can also be noticed that the addition of micro-lignin particles has a noticeable effect on the hardness of pmma composite specimens more than nano-zro2 particles, therefore, hardness for (pmma–micro-lignin) composite is higher than the values of hardness for (pmma–nanozro2) composite specimens. thus, the hardness value increased from (79) for pmma specimen (as referenced) to reach higher value of (84.5) for composite materials (pmma–2% micro-lignin). chart 6. shows hardness data of pmma composite denture base materials as function of (nano-zro2 or micro-lignin) particles content in composite. 6. conclusions 1. the (tensile modulus of elasticity, compressive strength and hardness) of pmma composite prosthetic denture (pmma–nano-zro2), (pmma–micro-lignin), were increased with the increasing of the volume fraction of (nanozro2 or micro-lignin) particles. 2. the (tensile strength, elongation percentage and impact strength) of pmma composite prosthetic denture (pmma–nano-zro2), (pmma–micro-lignin), were decreased with the increasing of the volume fraction of (nanozro2 or micro-lignin) particles. 3. the addition of (nano-zro2) powders has higher effect on the (elongation percentage, impact strength and compressive strength) properties of pmma composite prosthetic denture base specimens more than the (microlignin) particles. 4. the addition of (micro-lignin) powders has higher effect on the (tensile strength, tensile modulus of elasticity and hardness) properties of pmma composite prosthetic denture base specimens more than the (nano-zro2) particles. jawad kadhim oleiwi al-khwarizmi engineering journal, vol. 14, no. 3, p.p. 100111 (2018) 110 5. the maximum values for properties (tensile modulus of elasticity and hardness) were obtained in pmma composites prosthetic denture (pmma–micro-lignin). 6. the minimum values for properties (elongation and impact strength) were obtained in pmma composite prosthetic denture (pmma–nanozro2). acknowledgement the authors are grateful to the university of technology, baghdad, iraq, especially the laboratories of the department of materials engineering at this university to support it, which resulted in the completion of this research. 7. references [1] s. ramakrishna, j. mayer, e. wintermantel, k.w. leong, "biomedical applications of polymer-composite materials: a review", composites science and technology, vol. (61), pp. (11891224), (2001). [2] m.e. tuttle, "structural analysis of polymeric composite materials", marcel dekker, inc., (2004). [3] [3] k. j. anusavice, "phillips’ science of dental materials", 11th ed., w. b. saunders co., st. louis., pp. (145-737), (2008). [4] m. j. mustafa, "evaluation of candida albicans attachment to flexible denture base materials and heat cure acrylic resin using different finishing and polishing techniques", m.sc. thesis, university of baghdad, college of dentistry, iraq, (2011). [5] j. j. manappallil, "basic dental materials", 2nd ed., new delhi, ch 8, ch 20, pp. (99142), (346-377), (2007). [6] g. uzun and n. hersek, "comparison of the fracture resistance of six denture base acrylic resin", bio. appl. journal, vol. (17), pp. (19-29), (2002). [7] w. j. o' brain, "dental materials and their selection", 3rd ed., school of dentistry, university of michigan, (2002). [8] thielemans et. al., "novel application of lignin in composite materials", appli. poly. sci. journal., vol. (83), pp. (323-331), (2002). [9] s. o. koutayas, t. vagkopoulou, s. pelekanos, p. koidis & j. r. strub, "zirconia in dentistry: part 2. evidence-based clinical breakthrough", eur. jour. esthet. dent., vol. (4), no. (4), pp. (348-380), (2009). [10] annual book of astm standard, "standard test method for tensile properties of plastics d 638-03", vol. (08.01), pp. (1-12), (2003). [11] annual book of astm standard, "standard test method for compressive properties of rigid plastics d 695-02a ", pp. (1-8), (2002). [12] annual book of iso standard, "standard test method for unnotched izod impact testing of plastics, iso-180", pp. (1-2), (2006). [13] annual book of astm standard, "standard test method for plastics propertiesdurometer hardness, d 2240-03", pp. (1-12), (2003). [14] s. i. salih, j. k. oleiwi and q. a. hamad, "numerically and theoretically studying of the upper composite complete prosthetic denture", eng. & tech. journal, part (a), vol. (33), no. (5), pp. (1023-1037), (2015). [15] s. i. salih, j. k. oleiwi and q. a. hamad, "studying the tensile properties and morphology test for the self cured pmma resin of prosthetic complete denture", the iraqi journal for mechanical and material engineering, part (ii), vol. (special), pp. (508-522), (2015). [16] s. m. elie., "study of mechanical properties and thermal conductivity for polymer composite material reinforced by aluminum and aluminum oxide particles", m.sc. thesis, university of technology, baghdad, iraq, (2007). [17] s. i. salih, j. k. oleiwi and q. a. hamad, "investigation of fatigue and compression strength for the pmma reinforced by different system for denture applications", international journal of biomedical materials research, vol. (3), no. (1), pp. (5-13), (2015). [18] s. i. salih, j. k. oleiwi and q. a. hamad, "comparative study the flexural properties and impact strength for pmma reinforced by particles and fibers for prosthetic complete denture base", the iraqi journal for mechanical and material engineering, vol. (15), no. (4), pp. (288-307), (2015). [19] w. bolten, "engineering materials technology", 3rd ed., butterworth & heinemann publishing, ltd., (1998). )2018(100-111 ، صفحة3د، العد14دجلة الخوارزمي الهندسية المجلم جواد كاظم عليوي 111 اكبة بوليمريةلمادة قاعدة طقم األسنان مصنعة من مواد متردراسة الخصائص الميكانيكية قحطان عدنان حمد** جواد كاظم عليوي* *،** قسم هندسة المواد/ الجامعة التكنولوجية jawadkad@yahoo.com*البريد االلكتروني: oo.com@yah84qah**البريد االلكتروني: الخالصة والتي تمت في هذا البحث تم التقصي عن تاثير اضافة نوعين مختلفين من دقائق التقوية تضمنت دقائق الزركونيا النانوية ودقائق اللكنين المايكروية محضرة في هذا لكبة البوليمرية ا%)، على بعض الخواص الميكانيكية للمواد المترا ٢%، و ١٫٥%، ١%، ٠٫٥اضافتهما بكسور حجمية مختلفة هي ( َ مادة أساسبوصفها االسنان األصطناعية الكاملة او الجزئية، وذلك باستخدام راتنج البولي مثيل ميثا اكريليت المعالج ذاتياً قاعدة طقمل مادة بوصفها البحث . ا : المجموعة االولى تضم ما على شكل مجموعتين ه ق السباكة، وقد استخدمت طريقة (الصب اليدوي)ائباستخدام طر وقد تم تحضير عينات المواد المتراكبة تضمنت و راتنج البولي مثيل ميثا اكريليت مقواة بدقائق اللكنين المايكرويةا الثانية تضم راتنج البولي مثيل ميثا اكريليت مقواة بدقائق الزركونيا النانوية، و بان قيم خواص ظهرت نتائج هذه الدراسة أوقد االنضغاط، الصدمة، والصالدة. و ة التي تم اجرائها في هذا البحث فحوصات الشداالختبارات الميكانيكي ة قلت قيم خواص (مقاوم بينما. دقائق في المواد المتراكبة البوليمريةازدادت مع زيادة الكسر الحجمي لهذه ) مقاومة االنضغاط والصالدة(معامل مرونة الشد، على بعض خواص المواد المتراكبة دقائق اللكنين المايكرويةاكبر من اَ تمتلك تاثيرالزركونيا النانوية ان دقائق كذلك االستطالة ومقاومة الصدمة). و الشد .لهذه المادة على الخواص االخرى لاق اَ بينما تمتلك تاثير االسنان األصطناعية قاعدة طقممادة البوليمرية لعينات 1 al-khwarizmi engineering journal al-khwarizmi engineering journal,vol. 12, no. 2, p.p. 6078 (2016) weldability of new material sandwich steel for automotive applications ihsan kadhom abbas al naimi vocational education/ ministry of education e-mail: ihsan_kad@yahoo.com (received 17 may 2015; accepted 28 october 2015) abstract todays, world is faced an energy crisis because of a continuous increasing the consumption of fuels due to intension demand for all types of vehicles. this study is one of the efforts dealing with reduce the weight of vehicles by using a new material of sandwich steel, which consists of two skin steel sheets with core of a polymer material. resistance spot welding (rsw) can be easily implemented on metals; however a cupper shunt tool was designed to perform the resistance welding of sandwich steel with dp800 cover sheets to resolve a non-conductivity problem of a polymer core. numerical simulations with sorpas®3d were employed to test the weldability of this new material and supported by many practical experiments. in conclusion, it was found that the weldability could be improved with using two pulses and optimized their welding parameters. tensile-shearing tests were carried out to evaluate the strength of welding sheets. macro/micrograph and sem/eds examinations were also carried out to analyze welding area and compare the nugget of welding sheets with different welding parameters. the concluded optimum welding parameters are; 3.5 kn, (5.5 ka, 8 cycles), and (10 ka, 5 cycles) for the electrode force, welding current and time of first and second pulse respectively. keywords: sandwich steel , dp800, rsw, weldability, shunt tool , sorpas®3d. 1. introduction as long as there is ongoing intension demand of vehicles with all types, thus increasing fossil fuels consumption leading to real problems of pollution and global warming, scientists and automakers continue research on light materials to reduce fuel consumption and co2 emission as well as preserving the safety requirements, functionality and comfort in these vehicles. therefore, it is essential to find cost-effective solutions to these issues. one of these solutions is to used aluminum alloys sheets in automobile industry; however, the cost of these metals still high as well as the productivity of resistance spot welding aluminum is lower than steel [1-4]. rsw is a key technology in automotive assembly production. modern small vehicles contain (2000-5000) spot welds [5]. the process is very fast, low cost, minimum skill labor requirements, easily automated [6 and 7], and can weld many different material combinations that are difficult or even impossible to join by other welding techniques [8]. it is also suitable for small batch production, because the method is flexible, equipment simple and the welding process is easy to control. the process is also applied in manufacture of other transportation, household appliance manufacturers, and more. the most important adjustable rsw parameters are welding current, welding time, electrode force, and electrode geometry and its materials. the other adjustable parameters include the duration of squeeze and hold time, possible heat treatments before or after welding (pre/post weld), adjustment of the up-and downslope of the welding current (slope function), changes in electrode force and timing on the basis of work stage. in addition the pulsation of welding current which was used in this work. however, accurate control and synchronization of current and mailto:ihsan_kad@yahoo.com ihsan kadhom abbas al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 6078(2016) 61 electrode force is required for the process to get sound weldment [9]. in order to prevent noise and vibration from transmission as well as reducing weight, vibration damping steel sheets (vdss) which are composed of two steel-sheet skin layers and a viscoelastic polymer resin layer have been developed by steelmakers and has been commercially available since 1950. however, it is rarely used in high volume applications, such as those in the automotive industry [10]. the vibration damping steel sheets, however, must carry out spot welding by providing a bypass circuit, because polymer resin is electrical insulator. therefore, with parts requiring many weld spots, it is a difficult matter to carry out spot welding to provide a bypass circuit for every weld point. akihiko nishimoto and et.al. (1988) in nkk a japanese industries company developed the weldable vdss sheets which can be welded without the aid of bypass circuit device by adding nickel particles to the resin layer to solve the non-conductivity of the resin. they also analyzed many other particles additives to the resin such; fe, al, cu, sn, zn, and graphite with different size particles, and they concluded; nickel particles with size (44-74 µm) most optimum particles to make the vdss spot weldable even with 5 wt.% [11]. furthermore, other researchers investigated the weldable of vdss by the addition of filler particles and/or reduce resin thickness [12-15], but all solutions have a slight reduction of vibration damping performance. expulsion, which can be observed frequently during rsw, happens at either the faying surface or the electrode/work piece interfaces. the latter may severely affect surface quality and electrode life [16]. the risk of expulsion is especially high in spot welding of sandwich steel due to very dynamic and unstable character of the process, associated with melting and squeezing out the polymer core at contact area as reported by many researchers. oberle and et. al. (1998) optimized rsw parameters for vdss to avoid expulsion by minimizing welding current-rms during first welding cycle and using dome face electrodes [17]. the weldability of two variants (glued and brazed fibers) of thin sandwich stainless steel sheets with fibrous metallic cores was studied by tan and et.al. (2007), both variants were found to be weldable and forming good quality weld nuggets with optimum welding parameters: electrode force 2.5 kn, weld current and weld time 4 ka, 200 ms, respectively [18]. litecor ® is a new sandwich lightweight sheet developed and invented by thyssenkrupp steel for automotive applications, which consists of two thin outer layers and a core of polymer compound [19]. these new sandwich steel sheets are already used in inner parts; development target is outer panel parts. the development of new, sandwich steels for use in the automotive industry represents new challenges to the resistance welding of these steels as reported previously [20]. in this paper, a systematic study has been conducted on rsw of a novel sandwich steel (litecor ® ) with two dp800 cover sheets, by applying an electrical shunt tool in order to melt and squeeze out the polymer from the welding zone to perform the welding. numerical simulations with sorpas ® and many practical experiments were employed to evaluate the weldability of these materials. 2. experimental procedure workpiece materials, electrodes and welding equipment the experiments were conducted at the technical university of denmark (dtu). workpiece materials were a sandwich steel and dual phase (dp800) sheets. the sandwich steel sheet is a newly invented lightweight material by thyssenkrupp (german company producing many types of steels for automotive industries and others). the litecor ® (the commercial name of one type of sandwich steels) is produced with two thin outer layers of 0.2 mm steel sheets type bh200, and an interlayer of thermoplastic polymer compound 0.4 mm thickness, see fig. 1. fig. 1. the litecore ® ; sandwich steel sheet [19]. integrating the lightweight composite into the body-in-white is remarkably easy. it possesses the superior forming properties of conventional steel, with high flexural stiffness and buckling resistance; it combines high-level strength of steel with low weight of modern plastic. moreover, it is suitable for paint-shop. production starts with inner parts of vehicles and development target is outer panel quality, [21]. the density, tensile ihsan kadhom abbas al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 6078(2016) 62 strength, elongation, and hardness of the litecor ® which were tested at dtu are; 4.6 g/cm 3 , 200 mpa, 38%, and 80 hv, respectively, and the bending stiffness is 106% reference to steel. this composite material is very suitable to auto industrial. the cover sheets which were used to spot weld with sandwich sheet were hot-dip galvanized dp800 (dp stands for dual phase steel sheets consisting of a ferrite matrix and a hard second phase usually islands of martensite) steel sheets of 1.0 mm thickness, the properties and nominal compositions are shown in table 1. the delivered sheets were cut into 105 × 45 mm, with longitudinal dimension in the rolling direction. they were welded as a lap joint ready for subsequent tensile-shearing testing as shown in fig. 2 according to the international standard iso 14273 [22]. tensile-shear testing was carried out using amsler a universal testing machine at a deformation rate of 2 mm/min to determine the weld strength. a hard wood fixture was used to mount the samples in good alignment with the electrodes. a shunt tool was designed and made from pure copper, which was used in all practical experiments for conducting current in 1 st pulse. the electrode tips (female cap) were of type b0 according to iso 5821-2009 and the american standard rwma no. ff-25, [23]. they were made of zirconium-copper alloy (cucrzr) with the following chemical composition; cr: 0.71.2%, zr: 0.06-0.15%, bal. cu. the electrodes were of truncated configuration, ø16 mm in diameter with a flat tip surface of 6 mm, [24]. rsw experiments were performed on a tecna 8105 ac welding machine with weld controller of type te-180; specifications of the machine are listed in table 2. the welding current was measured by a rogowski coil together with a precalibrated tecna-1430 conditioner, and a kistler piezoelectric force transducer was used to measure the electrode load. the acquired data (daq) were treated on a pc by specially developed software in labview, see fig. 3. the following parameters of the rsw process were calculated for each experiment, current rms i (a), welding time c (s), and the electrode force p (kn). tensile-shearing tests were carried out using a universal testing machine at a deformation rate of 2 mm/min to determine the weld strength s (n). vickers microhardness measurements were performed using sophisticated instrument (future-tech, fm-700) with load of 100-g testing on weld cross-sections in longitudinal direction through the diameter of the nugget at intervals of 0.5-1.0 mm. macrographs and micrographs of the welds were made in light optical microscope (lom) type nikon me600. moreover, high-resolution images were made in sem, jeol jsm-5900 with lab6 filament applying secondary electron (se) at 20 kv, and using eds for quantitative chemical analysis. table 1, mechanical properties and nominal composition of dp800 cover sheets [25]. yield strength (mpa) tensile strength (mpa) elongation hardness (hv) chemical composition (wt-%) coating (zn) thickness c si mn cr al p s 500-640 800-950 12% 200 0.16 0.25 1.9 0.5 .015 .02 .004 7 µm 35.00 70.00 45 .00 175.00 fig. 2. schematic illustration of lap joint for tensile-shearing testing. table 2, machine specifications and image, tecna ac welder. specifications values specifications values controller te-180, 16 functions nominal power at 50% 250 kva supply voltage 380 v phases 1 frequency 50 hz supply pressure 6.5 bar max. welding current 68 ka electrode force per 1 bar 3.14 kn max. welding force 18.85 kn throat depth 250 mm max. welding power 810 kva water cooling 12 ℓ ∕ min ihsan kadhom abbas al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 6078(2016) 63 (a) (b) (c) fig. 3. instruments images, (a) computer used to collect all the measurements with (daq), (b) weld tester connected to rogowski coil, (c) transducer connected to load cell. welding of sandwich steel the sandwich steel (litecor ® ) has a polymer core between two steel sheets and it is required to weld with two other cover steel sheets. the polymer core does not conduct electricity; therefore current will not pass through proposed area and definitely there is no creation of nugget (welding area). preliminary studies by thyssenkrupp steel have proved that the lightweight sandwich steels can be resistance spot welded to other steel sheets with a special setup of shunt connection. the litecor ® was already used in the inner panel of some vehicles, and the goal is to use this material in the outer panel especially for light weight vehicle as electrical cars [26]. therefore, it is required for outer panel to weld the sandwich steel with other sheets in three combinations as shown in fig. 4; (1) with upper and lower cover sheets, which was used in this work, (2) with one cover sheet only, and (3) with two cover sheets in one side, as recommended by automaker. there are two challenges related with resistance spot welding of sandwich steel with cover sheets for inner panels including; non electrical conductivity of the polymer core and the severe expulsion of the polymer due to rapid melting and squeeze out of the polymer in the first stage of welding operation, which affects the quality of welding. while for the outer panels, there is a third challenge in addition of the two aforementioned challenges; it is not good appearance of the welding area due to the high indentation. however, a shunt tool was designed and made from pure coper to perform the resistance welding of sandwich steel with dp800 cover sheets to resolve a non-conductivity problem of a polymer core. fig. 5 illustrates the idea of using the shunt tool. the welding of sandwich steel with nonconductive electrical polymer core required two steps; the current passes through the shunt tool at first step, as shown in fig. 5-a, which needs the shunt tool to be close as much as possible from the electrode (proposed welding area), thus a high current will pass through metal sheets and will heat them, therefore the polymer core at this area will melt and squeeze out by electrodes pressure. once all four metal sheets have been contacted in this region the second step starts; the current will flow directly in the welding area and the generated heat will melt the metal in this region formation the nugget, see fig. 5-b. for this reason, in the 2 nd step needs the shunt tool to be far as much as possible from the electrode, because if not some of the current will pass through the shunt tool and will lose part of energy, and will adversely affect quality of the welding. thus, it is required to be accurate where selecting the distance between the electrode and the shunt tool due to the inversely relation of this selection of distance between the 1 st and 2 nd steps. thus, all simulations and practical experiments in this work were done with two pulses and some of them with three pulses. much effort has been devoted to find the optimum distance between the shunt tool and the ihsan kadhom abbas al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 6078(2016) 64 welding area by carrying out many numerical simulations and practical experiments. three different width of wood fixture were used related with this distance to find the optimum value, see fig. 6. but the results were discussed later are only with distance of 19 mm, which is used in this work. because of the lack of information on welding a new sandwich steel material, it was very difficult to find the optimum welding parameters. therefore, in the beginning of this work many simulations and optimizations with sorpa ® 2-d were carried out with different set up of welding current, welding time, electrode force, and multi pulses. fig. 4. three possible combinations for welding the sandwich steel with cover sheets fig. 5. (a) current flow through shunt tool 1 st step, (b) current pass through welding area 2 nd step. fig. 6. set-up for welding (left),three different thicknesses of hardwood-fixtures related with (d) (right). 3. results and discussion numerical simulations with sorpas ® 2-d commercial finite element numerical program sorpas ® from swantec [27] was used in this work. it is well known and most widely used as a numerical tool for simulation, optimization, and planning features of the resistance welding processes. it is based on mechanical, electrical, thermal, and metallurgical models. the resistance spot welding process of sandwich steel with other cover sheets is a 3-d case. however, this can be carried out with 2-d numerical simulation at first glance to get preliminary information about the welding parameters of resistance welding of litecor ® with cover sheets of dp800. due to the fact that litecor ® is a new sandwich steel material, therefore there is not much knowledge about the welding parameters and the conditions necessary to simulate the weld process with it. in order to carry out the simulations of the process, a special material data were prepared by swantec and implemented for the polymer core in the material database as with and without transformation, i.e. in case of 1 st step when the polymer in its location before heating and melting, and 2 nd step after squeeze out the polymer from the welding area. this treating of the polymer core in simulations is shown in the fig. 7. moreover, a third tool was added in setup of input data of simulation as a shunt tool for conducting electrical current between the cover sheets through the shunt connection, as shown in fig. 8, which illustrates in the bottom of the figure. the setup input values of this simulation include; 3.5 kn, (10 ka, 4 cycles), (14 ka, 4 cycles), and (14 ka, 4 cycles) electrode force, welding current and welding time for the three pulses respectively. when the sheets are heated up, the polymer core in the sandwich steel will be ihsan kadhom abbas al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 6078(2016) 65 melted and the outer sheets of the sandwich steel will be pressed into contact under the weld force. therefore, the resistance spot welding process will be realized when the steel sheets get into contact. fig. 9 shows the result of a previous setup simulation, fig. 9-a & b indicate the current flow as a current density (a/mm 2 ) before and after the polymer squeeze out, i.e. the current flow through the shunt tool and through the welding area respectively. while fig. 9-c indicates the temperature distribution in the sheets and the electrodes, as the same time it shows the heating and breaking of the polymer core, which is low melting temperature. fig. 9-d illustrates the final stage of the process and the nugget formation with splash arrow indicates the location of extrusion of the molten metal. the splash was occurred due to the high current set up input (14 ka) in the 2 nd and 3 rd pulses, which were more than the required current to form the nugget. more than 70 simulations were performed by changing the welding parameters input; welding current and time, and electrode force. some simulations were performed with 3 pulses instead of 2 pulses with slope of current in 1 st pulse to find the optimum of these values and the weldability of the litecor ® . fig. 10 shows the relation between the nugget size as an average diameter of the welding area and the heat input (j). this relationship is very normal because increasing the amount of electrical energy input will lead to increasing the amount of heat generated and thus an increase in the amount of molten metal forming a large welding area (nugget). table 3 shows the result some of selected simulations, which is ordered as maximum value of ratio of the nugget average diameter to the heat input (last column), which is always preferred to consume less energy and get the largest size of the nugget as stated in the rwma [9]. noteworthy, the values of the heat in the 3 rd column of this table were calculated already by the sorpas. while the average diameter of the nugget, which refer to the weld size (2 nd column) was calculated as the average of the two diameters (large and small diameter) of the oval (the normal shape of the nugget) were calculated by the program. the column of nugget/time in this table indicates the ratio of the nugget average diameter to the total process welding time, which is also preferred due to the fact that resistance spot welding designed as a very fast process and this is required especially in the auto manufacturing. the column of the slope 1 st pulse demonstrates if there is slope in this pulse or not, and the slope time, which is one cycle in many instances. after analyzing these simulations, it was concluded that the 1 st pulse should have a lower current than the 2 nd pulse due to the fact that first pulse function is only for heating and melting the polymer core, and the function of the second pulse is to form the welding by melting the four contact metal sheets in this region. the use of a third pulse did not improve much the quality of welding and so on for using slope in the first pulse. therefore, these functions were not used in the practical experiments. the results of these simulations were recommended that the optimum electrode force is 3.5 kn and this value was used for the most practical experiments and the simulations with sorpas ® 3-d. fig. 11 demonstrates the report of simulation no. (70), which is considered a good setup input, which led to a minimum splash and sufficient weld size. however, the gap between the current in the 1 st and the 2 nd pulse is equal to (9.5 − 5.5 = 4 𝑘𝐴), which is considered a large value and will adversely affect the welding machine and the lack of stability during welding process, and hence on the quality of the welding, as well as the risk that may be caused to workers. consequently, the numerical simulations greatly assisted while doing practical experiments through non exposure to the significantly problems, especially in the subject of the last conclusion. in the left bottom of the figure shows the weld growth curve. the nugget was start forming after 190 ms in the 2 nd pulse and continue growth until reach the maximum nugget size that is 4.539 mm, which is the upper limit of these input set up parameters values even if the welding continued up as a welding time increase, but the contrary, in the case of increasing the welding time adversely affect the welding quality due to increasing the expulsion of the molten metal. ihsan kadhom abbas al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 6078(2016) 66 fig. 7. set up of the input material data of simulation with sorpas ® 2-d. fig. 8. set up of the adding third tool as a shunt in simulation with sorpas ® 2-d. fig. 9. simulation results of spot welding of litecor ® with two cover sheets dp 800, (a) current flow in cover sheets through shunt tool, (b) current flow through welding area. (c) heating and breaking of polymer core, (d) nugget formation at the final process with splash arrow. ihsan kadhom abbas al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 6078(2016) 67 fig.10. relationship between the heat input and the nugget size table 3, results of some selected 2-d simulations fig. 11. report of simulation no. 70. i (ka) cycles i (ka) cycles i (ka) cycles 73 3.992 1813 12 5.1 7 8.52 5 no 3.5 3.327 2.202 54 4.516 2215 12 5.87 7 9.58 5 no 3.5 3.763 2.039 37 4.795 2385 8 8 4 12 4 3+1 3.5 5.994 2.010 70 4.539 2265 12 5.57 6 9.47 6 no 3.5 3.783 2.004 74 4.557 2277 13 5.87 8 9.58 5 no 3.5 3.505 2.001 50 3.947 1992 13 6 8 8 5 no 3.5 3.036 1.981 38 4.854 2561 8 8 3 12 5 2+1 3.5 6.068 1.895 62 4.988 2659 10 7.3 5 11.54 5 4+1 3.5 4.988 1.876 72 4.808 2570 12 6.9 7 10.18 5 no 3.5 4.007 1.871 59 4.777 2581 13 6.85 8 9.79 5 no 3.5 3.675 1.851 71 4.777 2581 13 6.85 8 9.79 5 no 3.5 3.675 1.851 55 5.108 2884 10 8.01 4 11.55 6 3+1 3.5 5.108 1.771 61 5.047 2904 8 9.96 3 12.58 5 2+1 3.5 6.309 1.738 66 5.359 3182 12 6.89 6 12.03 6 no 3.5 4.466 1.684 64 5.562 3366 9 7.67 4 14.31 5 no 3.5 6.180 1.652 43 5.369 3271 8 10 3 14 5 2+1 3.5 6.711 1.641 56 5.161 3149 10 9.23 4 11.75 6 3+1 3.5 5.161 1.639 60 5.643 3735 10 9.24 4 13.74 6 3+1 3.5 5.643 1.511 44 5.731 3893 10 10 4 14 6 3+1 3.5 5.731 1.472 65 5.989 4344 10 10.57 5 14.95 5 no 3.5 5.989 1.379 40 6.238 4527 12 10 4 14 4 14 4 3+1 4.0 5.198 1.378 39 6.112 4668 12 10 4 14 4 14 4 3+1 3.5 5.093 1.309 58 6.100 4682 16 9.43 8 12.29 8 7+1 3.5 3.813 1.303 slope 1st. pulse force kn nugget/ time nugget/ heat pulse 2pulse 1heat (j) nugget dia. avg. ex. no. total times cycles current type : ac pulse 3 ihsan kadhom abbas al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 6078(2016) 68 weldability of litecor ® the optimum welding parameters values were found from the numerical simulations, which were the only information available due to the recent development of the litecor ® . these simulations provided knowledge of the possible ranges of current, time, and force that were used later in the practical experiments to examine the weldability of the litecor ® with cover sheets of dp 800. it is worthy to point out that more than 50 welding processes were done and calculated the welding parameters by labview and excel sheet, then the welding specimens were examined for strength and macro/micrograph. the aim of all these experiments was to find the weldabilty of the litecor ® with dp800 cover sheets; weldability means the range of values from the minimum to the maximum of the welding current, welding time, and electrode force, i.e. the safety zone of the welding parameters and forming sound welding (good quality welding without defects). table 4 demonstrates some of selected experiments ordered as the ratio of the failure force in (n) to the current difference (gap). there are many details were mentioned in the table, the first fourth columns are the values set up input welding machine functions, followed by columns including the calculated values of the electrode force (kn) and current as rms (ka). moreover, a difference values between the current flowing through the shunt tool before melting the polymer core and the current flowing through welding area after squeeze out the polymer are included. this gap is very crucial especially with high values, which negatively influences the stability of the machine and welding quality, as well as the risk that workers may be exposed such as the splash of molten metal. the strength of the weldments and the mode of failure are included, which were tested in the lab by using a tensile-shearing test and the mode of failures were examined visually. the interfacial failure predominantly occurs with lower strength of the welding attributed to the smaller size of the nugget, and vice versa where plug (button) failure occurs with higher strength and larger nugget size, and this is in line with other researchers (ma and et. al) [28], pouranvari [29] and others. the welding time and the most of welding current setup in the 2 nd pulse were fixed at 5 cycles and 10 ka to analyze the welding process with different setup input of 1 st pulse, which is considered as a function of breaking and melting the polymer core. increasing the welding current input in 1 st pulse (20 ka) did not give good welding process due to the large gap (6.64 ka). in contrast, decreasing the welding current in the 1 st pulse gave a good welding. this is well illustrated in the fig. 12, a large gap (current before and after melt and squeeze out the polymer) means unstable process; (14.31-7.67=6.64 ka) as ex. no. (12), and a small gap means stable process; (8.375.50=2.87 ka) as ex. no. (16), this is well illustrated in the curve of electrode force. the set up input of the welding current in 1 st pulse preferably to be as lower value as possible with long time in order gap be a minimum value, however, a very low current input setup as (1 ka in ex. no. (35)) did not give a sufficient nugget size and good strength due to the delay of melting and squeezing out of the polymer, which occurs in 2 nd pulse not in the 1 st pulse as usual. although, an extreme increase in the amount of welding current in the first and second pulse as ex. no. (8), (11), (12), and (20), did not observe a significant increase in the welding strength, it believes the reason is that there is a large gap (current welding difference before and after melting the polymer). in conclusion, the ex. no. (32) is considered a good welding set up input, which gave a lower gap (2.22 ka) and high strength (12887 n). ihsan kadhom abbas al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 6078(2016) 69 table 4, results of some selected practical experiments. fig. 12 comparison between two experiments, (left) instability process (large gap), (right) good welding process (small gap). microhardness test a hardness characteristic of the resistance spot welds is one of the most significant factors influencing their strength and failure mode. the images of macrostructures including microhardness test points and their values for ex. no. (8), (12), (16), and (23) is shown in the fig. 13-a, b, c, d respectively. these specimens are selected for the different nugget sizes due to the different related welding parameters as shown in the previous table. the substantial difference in the composition of the constituent materials for spot welds led to a significant difference in microhardness from point to point. however, all points in the weld zone and in the haz exhibited a significant hardness increase from the base metals (bh200 & dp800), due to the high content of alloying elements in these steels as well as the high cooling rate. this conclusion is expected and 5 cycles 6 ka 11 cycles 12 ka welding time welding current welding time welding current 32 9 4 5 10 3.52 5.23 9.33 4.38 6.60 120 2.22 12887 5805 plug 3.30 27 9 7 5 10 3.50 5.81 9.54 5.00 8.02 140 3.02 14210 4705 plug 3.40 26 8 7 5 10 3.48 5.20 9.35 4.74 7.64 140 2.90 12985 4478 plug 3.35 30 8 6 5 10 3.49 5.37 9.58 4.72 7.55 130 2.83 12495 4415 plug 3.50 33 9 3 5 10 3.51 4.44 9.30 4.03 6.09 150 2.06 9016 4377 int. 3.10 29 6 9 5 10 3.48 5.77 9.31 5.46 8.40 100 2.94 12397 4217 plug 3.65 22 8 8 5 10 3.42 5.87 9.58 5.39 8.48 140 3.09 12985 4202 plug 5.15 16 7 10 5 10 3.47 6.07 9.66 5.50 8.37 120 2.87 12054 4200 plug 3.62 34 9 2 5 10 3.56 4.13 9.14 3.85 5.88 160 2.03 8428 4152 int. 3.20 19 8 10 5 10 3.48 6.98 9.82 5.97 9.38 120 3.41 13400 3930 plug 5.20 24 7 9 5 10 3.50 5.75 9.56 5.19 8.31 120 3.12 12114 3883 plug 4.40 23 8 9 5 10 3.51 6.36 9.74 5.31 8.79 120 3.48 12838 3689 plug 4.70 39 7 8 5 10 3.50 6.08 9.56 5.28 8.36 110 3.08 10633 3452 plug 3.45 8 3 25 6 15 3.48 9.24 13.74 9.24 13.74 80 4.50 14996 3332 plug 4.73 20 7 12 5 10 3.44 6.90 10.18 6.18 10.18 120 4.00 12936 3234 plug 5.20 28 6 8 5 10 3.50 5.15 9.38 5.15 9.38 120 4.23 11760 2780 plug 3.80 31 8 5 5 10 3.48 4.59 9.25 4.59 9.25 160 4.66 12838 2755 plug 3.65 11 6 20 5 15 3.51 10.99 12.35 7.29 13.54 60 6.25 15425 2468 plug 5.80 12 4 20 5 20 3.31 7.67 14.31 7.67 14.31 80 6.64 15092 2273 plug 6.00 35 9 1 5 10 3.64 3.69 8.86 6.06 9.12 210 3.06 5880 1922 int. 3.00 ex. no. machine setting functions input nugget size (mm) 1st. pulse 2nd. pulse 1st. pulse 2nd. pulse failure mode rising time (ms) current difference before and after rising failure force (n) ratio failure force to current difference before rising after rising calculated values force (kn) current rms (ka) ihsan kadhom abbas al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 6078(2016) 70 well-known from other researchers such as (ma and et. al. 2008). however, a very wide variation of hardness even within the weld area due to the litecor ® consisting of several layers and spot welded with two dp800 steel sheets. it is worthy to point out that the values of the hardness of the base metals for bh200 and dp800 are about 80 and 208 hv sheets respectively. fig.14 illustrates the profiles of the microhardness for the four specimens (8, 12, 16, and 23). all these specimens show highest magnitudes of hardness in the middle of the weld zone and start to fall towards the outskirts of the nugget due to the difference in the size of the crystal structure as a result of the different cooling rate from one region to another, whenever smaller crystal higher hardness. while the haz has also gained a very high hardness and this is clear in inflexion of the curves due to apparently attributed to the formation much of martensite result of the highest cooling rate in this region, which is the closest to the cold base metal. the difference in hardness curves arising from variation of the welding process parameters, where notice that the highest curve represents the hardest weld, which is the specimen no. 12 due to greater amount of heat input led to the formation of relatively large size of the nugget, and this is clear from the length of the curve compared to the other curves. the hardness curve of the specimen no. 16 is the lowest than the rest, which is smallest nugget size due to the lack of the amount of heat input during the welding process. while, the hardness curves of the two other specimens are located between the highest and lowest curves. figure 13 images of macrostructures including microhardness test points with table of their values. fig. 14. microhardness curves. macro/micrograph examinations dual phase steels typically consist two phases including; body centered cubic (bcc) 𝛼 −ferrite and a dispersed body centered tetragonal (bct) hard martensite in the form of islands, usually they are low-carbon low-alloy materials with 1040% martensite embedded in a ductile ferrite matrix [30]. there were a significant changes in the microstructures after spot welding the cover sheet dp800 with sandwich steel litecor ® , since these materials are transformable. light optical microscope was used to examine the microstructural variations as shown in fig. 15, which illustrates the macro/microstructures of the specimen no. 8 after spot welding. fig.15-a 50 150 250 350 450 -3 -2.5 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 2.5 3 h ar d n es s (h v ) distance from center (mm) s. 8 s. 12 s. 16 s. 23 ihsan kadhom abbas al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 6078(2016) 71 shows the macrograph of cross section of the weld area indicates all distinct regions including the base metals, haz, and the nugget with its diameter. the microstructure of the base metal of dp800 consists of eventually distributed martensite (white phase) within the ferrite phase (dark phase). martensite becomes larger and its volume fraction is higher in the haz than in the base metal as shown in outskirts of fig.15-b. if there is no other type of steel such as bh200 (outer layer of litecor ® ) in the center of the fusion zone was all that area full with martensite. the presence of this thin layer of steel with low carbon reduced the presence of the hard martensite, as shown in fig. 15-c, d, and e. however, this region showed hardness higher than the base metal as previously mentioned. to understand the variation in microstructure in resistance spot welds, the welding process parameters (electrode force, weld current, and weld time) are consider as a heat input. while the cooling rate depends on hold time and other factors, which is very high in this case, also needs to be considered. in this specimen (no. 8) no voids could be observed within the nugget. however, there is a deep penetration of electrodes toward the cross section of the sheets due to the high current passing through the welding area (9.23, and 11.75 ka rms for 1 st and 2 nd pulse respectively), and cause surface crack as shown in the fig. 15-f. for the same former reason, a large separation between welded sheets in the case of high welding current and electrode force setup input as shown in fig. 16, which represent the specimen no. 12. this specimen has a large nugget diameter (6.0 mm) due to higher welding rms current in 1 st and 2 nd pulses (7.67 and 14.31 ka) respectively. although this specimen has a large nugget size but the high welding current in the 2 nd pulse affects negatively in the welding quality, which represents by presence of very large void and cracks as shown in fig. 17. fig.18. demonstrates the comparison between specimen no. 16 and specimen no. 23 in the nugget size. the nugget diameter of specimen no. 16 is smaller than specimen no. 23 in spite of the current setup input in 1 st . pulse is higher (10 ka for s. 16 and 9 ka for s. 23), see table 4. it is therefore conclude that it is prefer to input set up a lower current and relatively long welding time in the 1 st pulse, for forming a good weld without defects and a suitable nugget size thus a sufficient strength. it is believed that the lower current input and longer welding time in 1st pulse; allow heating the sheets to a required temperature for melting the polymer core in the welding area without much penetration of electrodes into the sheets and not generate considerable heat, which leads to occurrence of the expulsion and the sheets separation. fig. 15. macro/microstructure images of specimen no. 8. ihsan kadhom abbas al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 6078(2016) 72 fig. 16. macrograph of specimen no. 12 indicating large sheets separation. fig. 17. macro/microstructure images of specimen no. 12. fig. 18. macro/microstructure images of specimen no. 16 (a), specimen no. 23 (b). sem/eds examinations micrographs were also made in sem to study microstructure and carry out high-resolution mapping determining chemical composition of areas of special interest by x-ray spectroscopy (eds). fig. 19 shows the microstructures of the welding area for specimen no. 8 and 23. there is no large variation in the microstructures between them due to the amount of heat input during the welding process almost equal, creating the same welding area and very close in size. high content of martensite is observed a result of the transformation because the metals contain a high percentage of carbon and manganese as well as the higher cooling rate because of the mechanism of the rsw process that focus the heat to a small area and in the contrast the adjacent areas will be cool. there is insufficient time for carbon diffusion at such high cooling rats. moreover, both the higher carbon and manganese contents in dp800 also result in a higher hardenability. no voids could be observed in these areas due to the welding parameters were below the case of expulsion. fig. 20 indicates the spectrum analysis of the welding area of specimen no. 8, significant variations in the proportions of the elements from one region to another, which is seen in image. the proportion of these elements are very close to what previously reported in table 1 that was adopted by the metal sheet supplier. the presence of metallic elements chromium and manganese being alloying elements in dp800, while having a little proportion of zinc metal is because of that sheet is coated with this metal. in the other hand, fig. 21 shows the spectrum analysis of surface of dp800 sheet, which is coated with zinc that is recorded in high proportion value (95.4%). while having a small presence of oxygen is believed due to the preparatory processes prior to implementation of sem tests. ihsan kadhom abbas al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 6078(2016) 73 fig. 19. sem images for specimen no. 8 and 23. fig. 20. spectrum analysis of specimen no. 8. fig. 21. spectrum analysis of surface of dp800 sheet coated with zinc. tensile-shearing tests tensile-shearing tests of the welded joints indicate their strength and the failure mode. fig. 22 shows the maximum fracture load for the spot welds as a function of the welding energy input specified in table 4. the energy input (heat) is calculated based on current squared multiplied in welding time for 1 st pulse plus 2 nd pulse, while other parameters are kept constant such as electrode force. therefore, it could be considered that electrical resistance value had been fixed for all practical experiments. the data point, which was represented in the figure, is the average of three specimens test. the mode of failure was recorded in each test and classified as one of the following three types: (1) interfacial failure (nugget fracture in shear), (2) plug failure (nugget pull-out), and (3) failure in the heat affected zone (haz). failure mode (1) typically occurs at low energy input indicating insufficient heating, in this case is about (600 ka 2 ×second). and mode (2) at sufficient energy input, which is a higher than 600 and lower than (1600 ka 2 ×second) indicating satisfactory heating. while mode (3) at a higher energy input, this is more than the last value indicating overheating and softening of the region near the nugget. it is seen in general that with increasing energy input the maximum load sustained by the spot-welded joints increases. the fracture load was seen to reach the maximum value in the range of energy input (1400 to 1600 ka 2 ×second). beyond this energy range corresponding to the expulsion, in line with other researchers senkara et al., 2004 [16]; pouranvari and ranjbarnoodeh, 2011 [31], and others, high heat input welding conditions lead to increasing the probability of expulsion occurrence as well as its extent and its associated electrode indentation. the electrode indentation induced surface cracks beyond the expulsion energy input, as shown in figure 17. the second impulse current condition was strongly influenced on the failure mode of ihsan kadhom abbas al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 6078(2016) 74 sandwich steel with cover sheets dp800, which in fact is associated with the microstructural changes occurring in the weld nugget. high current input setup in the 2 nd pulse will increase the electrode indentation, thus will not give good appearance, which is required especially with outer panel. because of high current setup input (20 ka) such as ex. no. 5 and 12 gave a deeply indentation as shown in fig. 23. and the same thing will be occur if the weld time is increased, heat conduction into the surrounding metals becomes greater, causing greater warpage, sheet separation, and deep indentation. in summary, mode (2) in failure exhibits strong welding and it is related with sufficient nugget size. therefore, the suitable range of the energy input is between 800 to 1600 ka 2 × second, and this is corresponding to (5-6) cycles and (1015) ka for welding time and current respectively. fig. 22. input in the maximum fracture loads versus welding energy tensile-shearing tests. fig. 23. strong indentation due to high current input setup, ex. no. 5. numerical simulations with sorpas ® 3-d a significant advantage of simulation over experiment in rsw, which allows the engineer to monitor different physical and mechanical phenomena occurring during welding. 2-d simulation by sorpas ® is quiet sufficient with many cases. however, welding the sandwich sheet with other cover sheets and using a shunt tool is not recommended to simulate with 2-d, since the case consider as a 3-d problems and this is in line with nielson and et. al. [32 and 33]. plenty effort has been conducted to simulate the case in 3-d sorpas ® by place the shunt as a third tool in the side end of the sheets for conducting electrical current between the cover sheets through the shunt connection, in addition of treating the polymer core in special input data as 2-d simulations. the meshes of the objects are shown in fig. 24, which presents the details of the mesh allowing a reasonable discretization without a huge number of elements. the mesh is refined in welding zone to be able to simulate the necessary gradients. besides mesh refinement, the elements are aligned strategically such that they follow the overall shape of the weld zone and in particular the contact zone defined by flat sheet round mesh. after finding the optimum welding time and current (8-9 cycles, 5-5.5 ka) for the 1 st pulse in numerical 2-d and practical experiments, using 3d simulation to find the the optimum welding time and current for the 2 nd pulse. a number of weld settings are simulated to show the influence of changing parameters. fig. 25 illustrates the current density, which indicates the current flow through shunt tool before the polymer core melted and squeezed out, i.e. the current does not flow through the contact area (proposed welding area). fig. 26 shows the process peak temperatures in the end of the weld time for simulated joint in sandwich steel with cover sheets for different weld settings (welding current and time). the images of the left part in this figure show the configuration with welding time setup equal to 2 cycles, this welding time is considered a very short time since there is no weld or bad shape nugget despite with high current (14 ka), which is considered very high value in the case of welding steel sheets with these thicknesses, see fig. 26-d. while the images of the right part in this figure show the configuration with welding time setup of 6 cycles. with low welding current (6 ka) no weld is yet formed and just start forming with welding current of 7.32 ka and the weld nugget increase in size with increasing current, but with 10 ka the nugget is very large and is negatively affected welding quality and the whole process especially of adhesion the sheets with the electrodes, see fig. 26-g. therefore, the range of weldability is narrow with this welding time (6 cycles). one of the best weld setting simulations is 5 cycles in time and 9.54 ka in current that seems clear in the nugget size and shape as shown in fig. 26-h. ihsan kadhom abbas al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 6078(2016) 75 fig. 27 shows the simulated nugget compared with macro etched cross-section nugget spot welded for ex. no. 23 with welding parameters 6.36 and 9.74 ka for current, 8 and 5 cycles for time. it can be seen that shape and size (4.7 mm) of the weld is predicted relatively a very fine fit with actual nugget as well as the haz zone. fig. 24. simulation mesh with 3-d sorpas ® for rsw sandwich steel with cover sheets fig. 25. current flow through shunt tool. fig. 26. process peak temperatures in the end of the weld time for different weld settings. fig. 27. comparsion between simulation and metallographic. 4. conclusions this study proved the success of using resistance spot welding on sandwich steel (litecor ® ) with dp800 cover sheets by using a cupper shunt tool for resolving a non-conductivity problem of a polymer core. it was found that the weldability could be improved with using two pulses and optimized their welding parameters. the significant conclusions drawn from this numerical and experimental work are as follows: 1. it is required to be accurate where selecting the distance between the electrode and the shunt tool because it needs the shunt tool to be close as much as possible from the electrode before melting and squeezing out the polymer and to be far as much as possible after that, 19 mm distance is quite sufficient. 2. as energy (heat) input increased the nugget size increased. however, where it reached its critical value (about 6000 j) the nugget size did not increase as the same proportion due to the expulsion occurred. 3. the hardness in the fusion zone and haz was more than two times higher than that in the base metals due to the formation of new martensite. 4. the maximum fracture load of welded specimen in tensile-shearing test is about 15.5 kn corresponding with welding current rms about 13 ka and welding time of 5 cycles. the failure mode is plug corresponding with more than 10 kn as fracture load, while less than this value failure is interfacial mode. 5. with increasing the current in 2 nd pulse as more than rms 14 ka, welding defects will occur such as large void and crack. 6. the optimum welding parameters are; 3.5 kn, (5.5 ka, 8 cycles), and (10 ka, 5 cycles) for the electrode force, welding current and time of first and second pulse respectively. 7. the existence of the new computer program, sorpas ® 3-d, provides the ability of simulating a variety of resistance welding cases such as this case that is not properly simulated by 2-d analysis. ihsan kadhom abbas al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 6078(2016) 76 acknowledgement this work is part of project to host the author at technical university of denmark dtu as a postdoc. the author would like to thank department of mechanical engineering at dtu, in particular dr. niels bay and dr. chris nielson and all colleagues at work. special thanks to wenqi zhang, director of swantec for supplying the license of sorpas ® program. 5. references [1] mathers g., (2002), "the welding of aluminum and its alloys", cambridge, united kingdom: woodhead publishing. [2] boomer d. r., hunter j. a., and castle d. r., (2003), "a new approach for robust highproductivity resistance spot welding of aluminum", sae technical paper 1-0575. [3] kim d. c., park h. j., hwang i. s., and kang m. j., (2009), "rsw of aluminum alloy sheet 5j32 using scr type and inverter type power supplies", int sci j; 38(1):55-60. [4] al naimi ihsan k., al saadi moneer h., daws kasim m., bay n., (april, 2014), "improving resistance welding of aluminum sheets by addition of metal powder", proc imeche part l: journal materials: design and applications(0) 1–10. http://pil.sagepub.com/content/early/2014/04/ 28/1464420714533526.full.pdf?ijkey=xf9k vxdgqe4ktzz&keytype=ref. [5] chao y. j., (2003). ultimate strength and failure mechanism of rsw subjected to tensile, shear, and combined tensile/shear loads. asme j. of engineering materials and technology, vol. 125, 125-13. 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[21] litecor® (august-2014), the intelligent solution for cost-effective lightweight design, [22] iso 14273:2000(e), "specimen dimensions and procedure for shear testing resistance http://pil.sagepub.com/content/early/2014/04/28/1464420714533526.full.pdf?ijkey=xf9kvxdgqe4ktzz&keytype=ref http://pil.sagepub.com/content/early/2014/04/28/1464420714533526.full.pdf?ijkey=xf9kvxdgqe4ktzz&keytype=ref http://pil.sagepub.com/content/early/2014/04/28/1464420714533526.full.pdf?ijkey=xf9kvxdgqe4ktzz&keytype=ref ihsan kadhom abbas al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 6078(2016) 77 spot, seam and embossed projection welds", licensed to swantec. [23] iso 5821: (2009), "resistance welding — spot welding electrode caps", licensed to swantec, iso store order #: 10-1067232. 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[31] pouranvari, m., and ranjbarnoode, e., (2011). resistance spot welding characteristic of ferrite-martensite dp600 dual phase advanced high strength steelpart iii: mechanical properties. world applied sc. journal 15 (11): 1521-1526. [32] nielson, c. v., zhang, w., martins, p. a. f., and bay, n. (2015). 3d numerical simulation of projection welding of square nuts to sheets. journal of materials processing technology 215, pp. 171–180. [33] nielson, c. v., zhang, w., perret, w., martins, p. a. f., and bay, n. (2014). threedimensional simulations of resistance spot welding. proceedings of the institution of mechanical engineers, part d: journal of automobile engineering, i-13. http://www.wma-sb.de/ http://www.ssab.com/ (2016) 6078، صفحت 2، العذد12دجلت الخوارزهي الهنذسيت الوجلم احساى كاظن عباس 78 قابليت اللحام لوادة جذيذة هي صفائح الفوالر الوركب لتطبيقاث الَورَكبَاث إحساى كاظن عباس النعيوي ٗصاسج اىرشتيح /اىرعييٌ اىَْٖي ihsan_kad@yahoo.com : االىنرشّٗي اىثشيذ الخالصت ٌُ اىيً٘ أَصٍحً ْشَمثاخفي اهي٘اخُٔ اىعاى ََ إُ ٕزٓ اىذساسح ٕي ٗاحذج . طاقح تسثة اىضيادج اىَسرَشج السرٖالِك اى٘ق٘د ّريدح ذعاظٌُ اىطية عيٚ خَيعِ أّ٘اعِ اى ِ اىف٘الر اىَشمة، ٗذرنُ٘ ٕزٓ اىَادج ٍِ طثقريِ سقيقريِ ٍِ ْشَمثاخ تِاسرخذاً ٍادج خذيذج ََ في )ٍِ اىف٘الر ٗسطَٖا ٍِ اىدٖ٘د اىري ىٖا عالقح ترقييو ٗصُ اى ً ذصَيٌ قطعح ّحاسيح ىرح٘يو اىرياس اىنٖشتائي ىحو ٍشنيح عذً يَنِ ذْفيز ىحاً اىَقاٍٗح اىْقطي عيٚ اىَعادُ تسٖ٘ىح، ٍٗع رىل فقذ خ. ٍادج ت٘ىيَش( اىقية أُخشيد . عاىي اىَقاٍٗح dp800 اىر٘صيو اىنٖشتائي ىيث٘ىيَش ٗإلذَاً ذْفيز ىحاً اىَقاٍٗح اىنٖشتائيح عيٚ اىف٘الر اىَشمة ٍع صفائح أخشٙ ٍِ اىف٘الر ّ٘ع د اىْرائح تعذد ٍِ اىرداسب اىعَييح sorpas®3dاىَحاماج اىعذديح ت٘ساطح ََ ذٌ اىر٘صو إىٚ االسرْراج اآلذي . الخرثاس قاتييح اىيحاً ىٖزٓ اىَادج اىدذيذج ُٗدِع َُ قاتييح اىيحاً يَنِ ذحسيْٖا تاسرخذاً ّثضريِ ٍِ اىيحاً ٗذثثيد أفضو ٍرغيشاخ عَييح اىيحاً ىٖاذيِ اىْثضريِ اىشذ -أُخشيد اخرثاساخ اىقص. ىٖزا اىثحث، إ اىري اىرُقِطَْد تاىَاينشٗسن٘ب اىض٘ئي ٗتاىَاسح اإلىنرشّٗي ٍع ( غيش اىَدٖشيح)ذٌ أيضاً ذحييو اىص٘س اىَدٖشيح ٗاىَشئيح . يٌ ق٘ج اىصفائح اىَيحٍ٘حٗىرق ثيٚ اىراىيحاىرحييو اىطيفي ىَْطقح اىيحاً ٗإخشاء اىَقاسّح ىريل اىَْطقح ٍع ٍرغيشاخ عَييح اىيحاً اىَخريفح، ٗاسرْردد اىَرغيش َُ ق٘ج ضغظ أقطاب اىيحاً : اخ اى . ىْثض اىيحاٍيِ األٗه ٗاىثاّي عيٚ اىر٘اىي( دٗساخ 5ميي٘ أٍثيش، 10)ٗ ( دٗساخ 8ميي٘ أٍثيش، 5.5)ميي٘ ّي٘ذِ، اىرياس اىنٖشتائي ٗصٍِ اىيحاً ٕي 3.5 mailto:ihsan_kad@yahoo.comالبريد mailto:ihsan_kad@yahoo.comالبريد 2027 al-khwarizmi engineering journal,vol. 11, no. 4, p.p. 20 modeling of mass transf department of bio-chemical engineering / (received abstract in order to make an improvement a reactor called as rotating perforated disc perforated. the transfer of oxygen from air to liquid phase was determined by measuring semicircular trough was used with a working liquid phase, while air was used as a gas phase. the effects of many parameters on the liquid phase mass transfer coefficient (k parameters are; the disc rotational speed ( that the value of kla was increased as the increased. while the values of (kla) was decreased continuously with increasing the clearance was developed for estimating mass transfer coefficient (k 0.460.63l frrex1087.4 n ak −= keywords: rotating biological contactor, mass transfer coefficient, wastewater treatment. 1. introduction rotating biological contactors are successful wastewater biological treatment system which has been developed. “they were widely used for the secondary treatment of domestic and industrial wastewater for cod/bod removal and nitrification/denitrification purposes “diffusion limitations and cod/bod removal kinetics coupled with diffusion of nutrients in biofilm reactors such as rotating discs were investigated by many researchers” [4 rotating perforated discs biological contactor (rpbc) which developed in this study contains a number of perforated discs which mounted on a horizontal “shaft axis of the bioreactor. the wastewater inlets the trough at a certain flow rate.the perforated discs are submerged to 40% into the wastewater. when the perforated discs were rotated by a shaft, the lower portion of the perforated discs that submerged in the wastewater khwarizmi engineering journal,vol. 11, no. 4, p.p. 2027 (2015) transfer coefficient in rotating biological perforated discs (rpbc) alaa kareem mohammed chemical engineering / al-khwarizmi college of engineering / university email: alaauniv@yahoo.com (received 16 august 2015 ; accepted 8 october 2015) to make an improvement associated with rotating biological contactor (rbc) disc biological contactor (rpbc) was developed in which the rotating discs transfer of oxygen from air to wastewater was investigated. mass-transfer coefficient determined by measuring the rate transfer of oxygen. a laboratory scale of ( working capacity of 40 liters capacity of liquid. synthetic waste gas phase. effects of many parameters on the liquid phase mass transfer coefficient (kla) were speed (n), the pore diameter (d) and clearance between the discs increased as the rotation speed (n) increased, and as the diameter of the pores in was decreased continuously with increasing the clearance was developed for estimating mass transfer coefficient (kla) in this type of bioreactor. 0.0120.230.46 ) d s () d d ( − rotating biological contactor, mass transfer coefficient, wastewater treatment. rotating biological contactors are successful wastewater biological treatment system which has they were widely used for the secondary treatment of domestic and industrial wastewater for cod/bod removal and nitrification/denitrification purposes ” [1,2,3]. diffusion limitations and cod/bod removal kinetics coupled with diffusion of nutrients in ofilm reactors such as rotating discs were [4 -7]. rotating perforated discs biological contactor (rpbc) which developed in this study contains a number of perforated discs which mounted on a shaft axis of the bioreactor. the wastewater inlets the trough at a certain flow rate.the perforated discs are submerged to 40% into the wastewater. when the perforated discs were rotated by a shaft, the lower portion of the ged in the wastewater would be turned to the upper atmosphere phase thus microbial film on the disc is in contact with the nutrients of the wastewater phase while the oxygen in the atmosphere would then perform its metabolism”[8]. “hence, the organic comp in the wastewater serve as the nutrients for the microbes to digest and grow. by such periodical operation, the microbes would grow, and a certain thickness of the sludge film would be obtained [9]. the rpbc was proposed due to its advantages such as high degree of turbulence would occur due to the movement of liquid between the discs through the holes within the discs, high specific surface area, low maintenance and power consumption.”the design of biological treatment processes for wastewater was by metcalf and eddy [10]. two approaches have been used to model the mass transfer coefficient in the rotating biological contactor (rbc). the first approach uses the relationship between mass transfer coefficient and al-khwarizmi engineering journal (2015) rotating biological contactor with college of engineering / university of baghdad contactor (rbc), a new design of biofilm which the rotating discs are transfer coefficient (kla) in the laboratory scale of (rpbc) consisted of a of liquid. synthetic wastewater was used as a a) were investigated. these between the discs(c). it was found of the pores in the disc (d) was decreased continuously with increasing the clearance(c). suitable correlation would be turned to the upper atmosphere phase thus microbial film on the disc is in contact with the nutrients of the wastewater phase while the oxygen in the atmosphere would then perform its hence, the organic compounds in the wastewater serve as the nutrients for the microbes to digest and grow. by such periodical operation, the microbes would grow, and a certain thickness of the sludge film would be obtained” [9]. the rpbc was proposed due to its as high degree of turbulence would occur due to the movement of liquid between the discs through the holes within the discs, high specific surface area, low maintenance the design of biological treatment processes for wastewater was described by metcalf and eddy [10]. two approaches have been used to model the mass transfer coefficient in the rotating biological contactor (rbc). the first approach uses the relationship between mass transfer coefficient and alaa kareem mohammed al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 2027 (2015) 21 both the reynolds number (turbulence) and froude number. the second approach is based on the effect of design parameters of contactors on kla such as the diameter of the discs, the rotational discs speed and the submerging level of the discs in the liquid.” [11]. several models were suggested for estimation “ the liquid phase mass transfer coefficient(kla)” for (rbc) such as thin biofilm model, friedman model and sant anna model [12]. the aim of this work is to study the effect of many design parameters such as rotational speed, disc pore diameter and clearance between discs on the mass transfer coefficient (kla) in the rotating biological contactor with perforated discs (bprc) as well as suggesting suitable empirical correlation to estimate the value of kla in (bprc). 2. materials and method 2.1. experimental set up “ specification of the bioreactor : the laboratory scale of” rotating perforated discs biological contactor (rpbc) was consisted of a forty liters trough of semicircular shape. the bioreactor consisted of two stages equal in volume. polyethylene (pe) perforated discs are constructed on a horizontal shaft one meter in length, which fit the trough length, through a central hole. twenty four perforated discs (25 cm in diameter) were carried in the trough,each stage of the trough contained twelve discs, which nearly result in a total disc area of 2.3 m2. “the discs were 40% submerged in the trough and rotated at (5-15) rpm. fifteen liters of wastewater was put in the trough in order to achieve the disc submerging depth of 40%”. dc motor was used as a prime mover to rotate the discs. five sets of discs were used, the first was non perforated discs while the others were perforated each with a certain pore diameter. four pore diameter were used; 0.25, 0.5, 0.75 and 1 cm in order to study the effect of pore diameter on the performance of the bioreactor. the dimensions of the bioreactor are shown in table 1. figure (1) shows schematic diagramme of the rpbc that used in this study. table 1, design details of rotating perforated disc biological contactor (rpbc). item dimensions no. of stages 2 no. of discs in each stage 12 diameter of the disc 25 cm thickness of the disc 0.5 cm shaft diameter 5 cm shaft length 100 cm ttrough width 45 cm ttrough volume 40 lit. total discs surface area 2.3 m2 fig. 1. schematic diagramme showing the design of the small-scale rpbc. (a) side view; (b) stainless steel shaft with discs; (c) cross sectional view. 1feed wastewater reservoir. 2effluent wastewater collector. 3polyethylene perforated discs. 4stainless steel shaft. 5trough. 6holes. 7peristaltic pump. 8motor. alaa kareem mohammed al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 2027 (2015) 22 2.2. synthetic wastewater in this study synthetic wastewater was used which contained of kh2po4, mgso4, urea and glugose. these materials were mixed in a such proportions to obtain composition of p/ n /cod = 2/ 15 /150”which is necessary for microorganisms to grow [12]. the value of cod concentration in the feed was adjusted about 2000 ± 200 mg/l. the ratio of p/ n /cod was kept constant during the experiment. mgso4 concentration in the feed was kept constant at 40 mg/l as well. the feed acidity ph was about 7 and increased to 7.8 in the bioreactor trough because of ammonia liberation that results from urea hydrolyses. 2.3. organisms culture of activated sludge was obtained from al-rustomiya industry wastewater treatment plant which located in the south of baghdad. this culture was cultivated in the laboratory on a shaker and used for the inoculation of the system [13]. 2.4. experimental work initially batch wise experiments were carried out. fifteen litters of synthetic wastewater were put in the trough.‘‘ the wastewater was inoculated with activated sludge culture. the bioreactor (for both set up; perforated and non-perforated discs) were operated batch wise by changing the media in every four days until significant biofilm was noticed to be developed on the surfaces of the discs’’ [11]. the batch operation last for three weeks to obtain a biofilm thickness of about 1.5 – 2 mm. during the continuous operation, feed of wastewater was supplied from the reservoir tank on the inlet side of the bioreactor by means of the peristaltic pump at a constant flow rate of 40 ml/min resulting in a hydraulic retention time of about 6 hour. the outlet of wastewater was collected into a separate collection tank placed at the outlet of the trough. “experiments were carried out at temperature 23 ± 2oc and ph = 7.8± 0.4. ph was adjusted at 7.8 by adding dilute sulfuric acid manually. the thickness of biofilm,formed on the discs surfaces, was manually controlled at 2 mm by skimming the excess thickness of biofilm. for each experiment, the system was operated for one week. “to evaluate the mass transfer coefficient kla, the dissolved oxygen (do) concentration in the wastewater was instantaneously measured using (do) probe which was calibrated with distilled water” . nitrogen gas was supplied to the liquid phase until the dissolved oxygen (do) concentration reached to about 0.2 mg/l. after that nitrogen addition was stopped , then the discs were begin to rotate” . 2.5. calculation of liquid phase mass transfer coefficient (kla) oxygen transfer rate was used to determine the mass transfer rate coefficient kla. “a meter of dissolved oxygen was used to measure the oxygen transfer rate” . the oxygen transfer rate is given by the following equation: )ca(ck td c d o2 * o2l o2 −= …(1) where co2 is the concentration of dissolved oxygen in the synthetic wastewater at time t and c�� ∗ is the saturation concentration. oxygen probe was tested to show its order response. it was shown that the probes gave a first-order response, with a time constant of about 7 seconds. “the expression for the probe can be written as” )c(c k td c d po2p p −= …(2) where cp is the concentration of oxygen measured by the probe and kp is the probe constant. the values of the kp depend on the transport characteristics of the probe membrane” [13]. the following dimensionless quantities were introduced: y�� = � ∗ � � � ∗ � � � …(3) cc cc y o p * p p * p p − − = …(4) rewrite eqs 1 and 2 in dimensionless form as y ak td y d o2l o2 −= …(5) )y (y k td y d po2p p −= …(6) where c � and c�� � are the concentrations of dissolved oxygen at time t = 0, cp* is the probe saturation concentration. but c � = c�� � and cp *= co2 *. equations (5) and (6) were solved simultaneously” . the following equation was obtained: alaa kareem mohammed al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 2027 (2015) 23 akk ekek y lp tk la tak p p pl − − = −− …(7) “the value of kp can be evaluated from the probe response to a step change input by transferring the probe from a container of water saturated with dissolved oxygen (c��= c�� ∗ ) to a container of oxygen-free sulfite solution (c��=0) and noting the probe reading”[13]. by assuming a value of kla, the value of yp for a given time was calculated by eq. 7. then, the value of the error for a given kla in a given time was calculated according to the following equation ) y yy (error 2 pa pepa − = …(8) the value of kla was calculated from eq. (8). the best value of kla will give the minimum value of error. so value of kla can be calculated by minimizing the total error in eq.(8) using the golden section optimization algorithm”[11]. 3. “ results and discussion ” 3.1. effect of rotation speed ” the effect of rotational speed (n) on the value of mass transfer coefficient (kla) was studied for both perforated and non-perforated discs. four values of (n) were used such as 3, 6,9 and 12 rpm. figure(2) shows that the value of mass transfer coefficient (kla) was increased till about n= 9 rpm after which the increasing rate become low and get nearly constant value at 0.058 s-1 for perforated disc and about 0.045 s-1 for nonperforated discs. increasing rotational speed will lead to much turbulence in the broth solution in the trough. this turbulence will lead to decrease the biofilm thickness and hence results in increasing the value of liquid phase mass transfer coefficient (kla). this finding is in agreement with friedman who “studied the effect of disc rotational speed (n) on biological contactor performance” [11]. he noticed that with the doubling the value of (n), about 25 -30% improvement occur in the efficiency of the bioreactor. figure (2) shows that the values of mass transfer coefficient (kla) for perforated discs are nearly 19 25% greater than those for non-perforated discs, this may be due to the high degree of turbulence that made by moving the broth solution through the holes of the discs during agitation of the broth. fig. 2. variation of mass transfer coefficient (kla) with rotation speed ( n) (pore diameter d = 1 cm and clearance c= 2 cm). 3.2. effect of total perforated disc area (a*) in order to investigate the effect of total perforated area in the discs on the contactor performance in removing cod of the wastewater, four values of percent of perforated discs areas were studied; (a*/a)=10, 20, 30 and 40%. where (a) is the total disc area and (a*) is the total area of the pores in the disc. these tests were carried out for three values of pore diameter (d= 0.5, 0.75 and 1 cm). figure 3 shows that the % cod removal increases as the percent of perforated disc area increased until it reaches 20% after which it begins to decrease and reaches low value at percent of area of 40%. this can be interpreted as; in the beginning increasing pores in the discs will help making turbulence by moving the liquid between the discs through these pores which lead to decrease the biofilm thickness and hence increasing the value of mass transfer coefficient (kla) which leads to increase %cod removal [12,13]. but more increase in perforated disc area will lead to decrease the solid contact area of the disc with the biofilm and hence decrease the mass transfer rate which will decrease the % cod removal. 0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 3 6 9 12m as s tr an sf er c oe ffi ci en t (k l a) ,s 1 rpm perforated discs non-perforated discs alaa kareem mohammed al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 2027 (2015) 24 fig. 3. effect of perforated disc area on percent cod removal. (clearence c = 2cm and rpm = 12). 3.3. effect of the pore diameter (d)” “ the effect of the diameter (d) of pores within the disc on the value of mass transfer coefficient (kla) was investigated” . four values of pore diameter were investigated; 0.25, 0.5, 0.75 and 1 cm. figure (4) depicts the variation of kla with pore diameter at different values of rpm. it was noticed that the effect pore size appear significantly at values of rotation above 8 rpm. figure (4) shows that the values of kla increased as the diameter of the pore increased till the values of 0.75 cm after which the difference in increasing the values of kla is not significant. also it was noticed that as the pore diameter is decreased the values of kla approach that of blind disc (disc without holes). the holes in the rotating discs can take part in making surface turbulent during the rotation by the movement of liquid between the compartments through these holes. this turbulence will not permit building a heavy biofilm on the discs and hence improving the values of mass transfer coefficient in the liquid side (kla). this finding is in agreement with that found by cupta who showed that the value of mass transfer coefficient was increased when they introduced aeration turbulence in the trough of brc [14]. fig. 4.“ effect of hole diameter on mass transfer coefficient kla. (clearance c = 2 cm ). 3.4. effect of clearance (c) effect of clearance (the distance between two consecutive discs) was investigated to show its effect on the value of mass transfer coefficient (kla). three values of clearance (c) were selected; 2, 3 and 4 cm. figure (5) shows that the values of liquid phase mass transfer coefficient (kla) are decreased with increasing the value of clearance (c) that is due to the decreasing in the degree of turbulence occurring in the liquid phase between compartments which occur by rotation of the discs as well as the movement of circulating liquid through the holes of the discs. similar finding was observed by alaa who showed that increasing the clearance cause the region near the middle distance between compartments to become a weak agitation or a dead zone region and hence the turbulence within the fluid decreases the point which decreases the value of kla. [15] 0 10 20 30 40 50 60 70 80 90 0 10 20 30 40 50 % c o d r e m o v a l percent perforated area (a*/a) "d=0.5 cm" "d= 0.75 cm" "d=1 cm" 0.000 0.010 0.020 0.030 0.040 0.050 0.060 0 3 6 9 12 15m as s tr an sf er c oe ffi ci en t k l a, s -1 rpm " no holes " " d=0.25 cm " " d=0.5 cm " " d= 0.75 cm " " d =1 cm " alaa kareem mohammed al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 2027 (2015) 25 fig. 5. effect of clearance on the value of mass transfer coefficient kla. ( rpm = 12 and pore diameter d = 1 cm ). 3.4. dimensional analysis in order to establish a mathematical correlation between mass transfer coefficient (kla), and the variables which investigated in this work: rotation speed (n), diameter of pores in the discs(d) and the clearance(c), the experimental data for this system were analyzed using dimensional analysis. kla was assumed to be a function of several factors [16]; thus, kla= f (n, d, d, s, g, µ, ρ) …(11) from dimensional analysis, it was noticed that the overall mass transfer coefficient can be related to dimensionless groups reynolds number (re) and froude number (fr), pore to disc diameter ratio(d/d) and clearance to disc diameter ratio(s/d),through the following equation: ) d s () d d (frrex1087.4 n ak 0.180.230.460.63l −−= …(12) where re = � � ρ µ and fr = � � � from eq.(12) it was noticed that the rotation speed (n) has the most effect on the value of (kla). 4. conclusion it was found that in rotating perforated disc biological contactor(rpbc) the value of the masstransfer coefficient (kla) was increased as the rotation speed (n) increased, and as the diameter of the pores in the disc (d) increased. while the values of (kla) was decreased continuously with increasing the clearance(c). the percent cod removal was found to be increased as the percent of perforated disc area increased until it reaches 20% after which it begins to decrease and reaches low value at percent of area of 40%. the values of kla in the biological perforated disc contactor (bprc) were found to be 19 -27 % greater than that in nonperforated disc(brc). suitable correlation was developed for estimating mass transfer coefficient (kla) in this type of bioreactor. from dimensional analysis, it was noticed that the overall mass transfer coefficient can be related to dimensionless groups; reynolds number (re), froude number (fr), pore to disc diameter ratio(d/d) and clearance to disc diameter ratio(s/d). 5. nomenclature a cross sectional area of the disc (m2)” a* total area pores within the disc (m2)” a interfacial area per unit volume (m2/m3)” bod biological oxygen demand co2 concentration of o2 in the bioreactor (g/l)” c*o2 concentration of saturated oxygen in the bioreactor (g/l)” cp concentration of o2 measured by probe (g/l)” c*p concentration of saturated oxygen measured by probe (g/l)” c�� � oxygen concentration of o2 at t = 0, cm0, (g/l)” c � probe oxygen concentration at t = 0 (g/l)” c clearance between two consecutive discs (m)” cod chemical oxygen demand d “pore diameter, (m). d disc diameter (m)” dab difussivity of o2 through liquid(b)” fr froude number n2d/g g gravitational acceleration (m/s2) kla mass-transfer coefficient (s-1) kp probe constant (s-1) n rotational speed (s-1) re reynolds number nd2ρ/µ t time (s) ym dimensionless oxygen concentration in the bioreactor p phosphor ρ density of liquid (kg/m3) µ viscosity of liquid (pa.s) 0.000 0.010 0.020 0.030 0.040 0.050 0.060 2 3 4 m a ss t ra n sf e r co e ff ic ie n t k la , s -1 clearance c, cm perforated discs nonperforated discs alaa kareem mohammed al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 2027 (2015) 26 6. references [1] prashant, a. k.; rao, y.r. (2012). “a review of rotating biological contactor system” ijera 2(5): 2149-2153. [2] chin, j. (2003). “a theoretical analysis on the biofilm reactors.” inst. chem. engrs., 34(6): 643-653. [3] kossay, k. al-ahmady (2005). “effect of organic loading on rotating biological contactor efficiency”. int. j. environ. res. public health. 2(3): 469-477. [4] prashant, a. k.; amruta, a.b. and rao, y.r. (2013). “treatment of municipal wastewater by using rotating biological contactor rbc”. american journal of eng. research. 2(4): 127132. [5] tawfik, a.; klapwijk, a.; el-gohary, f. and lettinga, g. (2005). “potentials of using an rbc for post treatment of anaerobically pretreated domestic wastewater.” biochemical engineering journal, 25(1): 89-98. [6] mba, d. and bannister, r. (2007). “ensuring effluent standards by improving the design of rotating biological contactors”. desalination, 208(1): 204-215 [7] chan, y. j.; chong, m. f., law, c. l., & hassell, d. g. 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[12] kargi, f. and serkan, e.(2003). “ performance of rotating perforated tubes biofilm reactor in biological wastewater treatment. enzyme& microbial technology. 32 (3): 464-471. [13] fikret, k.(2001). “rotating-perforated-tubes biofilm reactor for high-strength wastewater treatment.” journal of environmental engineering, 127 (10): 959 – 963. [14] cupta s.k. and vijary, k.s. (2012). “model for oxygen transfer in rotating biological contactor”. j.chem. technol.and biotechnology. 87(4): 540545. [15] alaa k.m. (2008). “mass transfer characteristics in bioreactor contactor”. alkhwarizmi engineering journal, 4(3):66-73. [16] vijay, k. ; sanjeev, c. and cupta, s.k. (2004). “model for oxygen transfer in rotating biological contactor.” 38(20): 4297 – 4304. ��� 4، ا���د��11 � ا���ارز�� ا������� ا��� � ��ء ��� ����� ،2015( 2027( 27 ) %�)'� ��!�& ا%$#!ل ا��!دةklaا����ي ذ ( &�!� )rpbc(ا�01اص ا��.#�-� ا��وارة ي+� ا�� ��ء ��� ���� dst 9uk<vاد/ pq:9 ا9cdefb اnobارزghi /jk ا9cdefb اab:@:>;:9 ا<=:>;:9 jwوyzab>ا d[y\bا: alaauniv@yahoo.com ا����� 9]puz@bات اy[n_zbا `ut اءyvض اysbوارةdbاص اyi>ز ا<fet 9 يذ[n:hb9 اeb<u@bا )rotating biological contctor, rbc ( gت 9\]jk اصyi>ن اnaت l:ht ز<febا اmfb d[dv g:@nاث تdhzcز .ا<feb9 ا:@hت gوت)rotating perforated biological contctor ,rpbc(. ان jq اfeb>ز )rpbc(تnaن ا<yiاص jk y:y[\e:t 9@> تnaن jk[\rbc ( 9( رة، jwq اfeb>ز ا<ولا<tzuف r:t اfeb>ز]r ]jq r@a ط\:9u ا<yiاص اdbوا jw<jb9. اuen@bف اynbه ا<:k {bاء اnfbا rk r:ehqل ا<و<]zwل اduk 9cدرا gت )synthetic ( |;<hbا }w<v jq دة<@bل ا<]zwا |k<uk ب<h= �bmqو)kla( rk r:ehqل ا<و<]zwل اduk س<:i لtu . �:enت gز ذت<fv9 ي[n:hb9 اpk<u@pb 9tn]j@bاص اyi>ا )rpbc ( 9uht 9[y;دا �nw 9wاn_cا rk نnaz[ يmb٤٠وا yzb ا\:�i يnhر] >تnhk< tt<i g�9�yc : ھmه اnubاk| ھkla (j(تg درا9c ت>�:d� yة �nاk<uk 9@:i {p� |k| اzw[>ل اb@>دة . >yi< tn]jkص dpb٢٤وران [ �e:t اzeb>;� ان k<uk| اzw[>ل اb@>دة ]�داد �t]>دة s .( 9�yc( اyi |q r:t 9:e:\bص:r::b<zzk r ا9q<h@bو) d(، y_i اn]jbب jq ا<yiاص )n(دوران ا<yiاص تg ا]e>د �9it تye]\:9 ت�ty اk<uk r:t 9itub| اzw[>ل اb@>دة . دوران ا<yiاص و�t �bmq]>دة y_i اn]jbب e:t@> ت[| t �z@:i>زد]>د ا9q<h@b اr:t 9:e:\b ا<yiاص )kla (و <fzcدرا gت jzbات اy:sz@bواhebا �qو {p�jا<ت n: 0.0120.230.460.63l ) d s () d d (frrex1087.4 n ak −−= <4d6963726f736f667420576f7264202d20edc7d3e3ede420e6dac7d5e320e6dae1c7c13130372d313135> al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 14, no.2, june, (2018) p.p. 107115 cellulose fibers dissolution in alkaline solution yasmeen salih mahdi* asem hassan mohammed** alaa kareem mohammed*** *,***department of biochemical engineering/ al-khwarizmi engineering college/ university of baghdad ** institute of technology baghdad/ chemical industries/ middle technical university *email: yasmeensalih90@gmail.com **email: asemh2005@yahoo.com ***email: alaauniv@yahoo.com (received 3 october 2017; accepted 14 november 2017) https://doi.org/10.22153/kej.2018.11.005 abstract in this study, naoh dissolution method was applied to dissolve cellulose fibers which extracted from date palm fronds (type al-zahdi) taken from iraqi gardens. in this process, (naoh)-solution is brought into contact with the cellulose fibers at low temperature. experiments were conducted with different concentrations of naoh (4%, 6%, 8% and12%) weight percent at two cooling bath temperatures (-15 oc) and (-20oc). maximum cellulose dissolution was 23 wt% which obtained at 8 wt% concentration of naoh and at cooling bath temperature of -20oc. in order to enhance the cellulose fibers dissolution, the sample was pretreated with fenton's reagent which consists of hydrogen peroxide (h2o2), oxalic acid (c2h2o4) and ferrous sulfate (feso4). this reagent reacts with cellulose fibers and produces free radicals which increase cellulose dissolution. in this work three variables were studied: cooling bath temperature (15ocand-20oc), naoh concentration (4%, 6%, 8% and12%) and time of fenton's reagent treatment (1-48) hrs. the results showed that the best percent of cellulose dissolution was (42 wt %) which occurred at treatment time (24 hours), temperature (-20oc) and naoh concentration 8%. in another set of experiments urea was added to naoh solution as a catalyst with proportion (6%naoh+4% urea) at two temperatures -15 and -20 oc. the results show that the solubility of cellulose increase to 62% for the sample which treated with fenton's reagent and to 35% for the untreated sample, both values were obtained at -15oc. keyword: dissolution of cellulose, cellulose fibers, fenton's reaction. 1. introduction dissolution of cellulose is a kinetic process where the forces that maintain the crystalline structure are overcome and lead to the disintegration of the structure into molecules [1]. the forces include the hydrogen bonds within the chain (intramolecular) and between the neighboring chains (intermolecular), as well as the van der waals forces and hydrophobic forces. the dissolution occurs when such a solvent is introduced to polymer which is able to disturb the mutual interaction of the polymer molecules [2]. cellulose is a linear, semi-flexible polymer that is self-organized in crystalline and noncrystalline phases. since cellulose cannot melt, dissolution is a major issue. cellulose solutions are used for processing cellulose in the form of fibers, films, membranes or other not too bulky objects such as sponges or aerogels, or for performing chemical derivatisation. since cellulose chains have no specific features, the cellulose must be dissolved as occur to any other flexible or semi-flexible polymer, and cellulose solutions should behave as normal polymer solutions [3]. the development of cellulose dissolution/regeneration strategies constitutes an increasingly active research field. these are fundamental ways of several production processes yasmeen salih mahdi al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 107115 (2018) 108 and applications. a wide range of appropriate solvents for cellulose is already available. however, most solvent systems have significant limitations, and there is intensive activity in both industrial and academic research aimed at improving existing solvents and developing new ones. cellulose solvents have very different nature which gives great challenges in understanding the delicate balance between different interactions [4]. previously, several traditional solvent systems were introduced. one of the famous methods to dissolve cellulose was cs2 method (viscose type), which was the oldest and complex procedure for producing rayon [5]. in this way, a prior chemical modification of the molecules was needed, leading to serious environmental pollution and poor human health. consequently, due to these defects, non-derivative solvent systems are more acceptable were used, inclusive ammonium fluorides /dimethylsulfoxide (dmso), n, ndimethylacetamide/ lithium chloride (dmac/licl), and also n-methyl-morpholine-noxide (nmmo) [6]. these three solvents accumulate with a several structure and are thought to dissolve the cellulose without breaking any existing chemical bonds. another solvent is sodium hydroxide used to dissolve cellulose, recently the main focus was placed on the aqueous alkaline solvents due to consideration of being inexpensive, harmless and ecofriendly, so sodium hydroxide can be regarded as the most suitable solvent for cellulose dissolution [7]. the purpose of the current study is to dissolve cellulose which extracted from date palm fronds after treated it with fenton's reagent and sodium hydroxide solution with and without urea under controlled conditions. 2. experimental work in order to carry out dissolution process of cellulose fibers, several steps must be conducted. first, the quantitative analysis of date palm frond was done to identify the cellulose content in the fronds. secondly, the sample was delignificated using modified organosolv to remove lignin from biomass (date palm fronds). in the third step the sample was bleached to remove most of the remaining lignin and hence increasing cellulose content to about 96%). the last step includes dissolving cellulose fibers using naoh solution with and without urea. 2.1 compositional analysis of data palm fronds the samples of date palm fronds were collected in the summer season from babylon farms from a kind of date palm named (al-zahdi) and stored in presterilized bags in refrigerator freeze. the samples then taken to the laboratory for test and before being treated, impurities should be removed by washing them with distilled water several times .after that, the samples were shredded using electric cutter and crushed with humor then sieved. fragments with a particle size of (270-90) μm were selected to be used in the next steps [8]. table (1) shows the composition of fronds (leaves and stalk). table 1, the composition of date palm fronds (leaves and stalk) based on dry weight wt/wt sample carbohydrate lignin ash extractive protein leaves 52 26 8 10 4 stalks 59 23 7 8 3 2.2 delignification lab scale experiments were performed in two liter autoclave batch reactor. the date palm fronds (biomass) were milled to about 0.18mm. a suspension of biomass-water-organic solvent (ethanol) was made (typically, 200 ml solvent per 20 g biomass). the experimental parameters in the delignification process were: temperature, ethanol /water ratio wt/wt and digestion time. from previous study, the optimum conditions for delignification process were: temperature 185oc, ethanol: water 50:50 and digestion time 80 min [9]. in order to reduce the digestion time, three types of catalyst were tested: h2so4, naoh and ca (oh) 2. among them, sodium hydroxide (0.025m) was found the best one which reduces the time from 80 min to 30 min. the aim of delignification, is to remove lignin and hemicellulose and obtain pure cellulose [10]. 2.3 bleaching bleaching is a chemical treatment performed to different types of wood pulp to remove pulp color so that it becomes whiter. the objective of yasmeen salih mahdi al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 107115 (2018) 109 chemical bleaching of the pulp is basically to remove all of the remaining lignin. so the process is often referred to as delignification [11]. chlorine is the basis for the most common bleaching processes. three grams of dried sample was weighted and put into 500 ml flask, then 250ml of sodium chlorite solution (60 gm per liter sodium acetate and 60 gm per liter sodium chlorite) was added, the sample was then soaked for four days[12]. after that it was washed with deionized water, followed by extraction with naoh (0.15 n) several times and then it was washed with hypochlorite and distilled water. finally, the sample was dried. it was noted that the color was changed from dark brown to white (this means eliminating the lignin and the remaining was mainly cellulose as shown in figure (1). fig. 1. the sample after bleaching. 2.4 fenton's reagent fenton's reagent is a solution consists of hydrogen peroxide with ferrous iron as a catalyst that is used to oxidize contaminants or waste waters. it was developed in the 1890s by henry john horstman fenton as an analytical reagent. the traditional fenton reaction is the catalyzed decomposition of dilute hydrogen peroxide (h2o2) by iron (ii) to form radicals of hydroxyl. h2o2 + fe2+ → fe3++ •oh + −oh 2.4.1 fenton's reagent preparation fenton's reagent can be prepared by mixing: (80mm h2o2, 0.5mm feso4, 10mm oxalic acid, 10mm sodium oxalate), mixing between oxalic acid and sodium oxalate was according to the following volume ratio: (1:13) to reach ph= 4.6-5 [13]. 2.5 cellulose dissolution procedure 1. solutions of sodium hydroxide were prepared with different concentrations (6%, 8%, 10% and 12%) weight percent. for example to prepare 6% wt, 6 g of naoh is completed to 100 ml by adding 94g distilled water [14]. 2. the sample which bleached before was treated with fenton's reagent by taking 0.2 g of the sample (mainly cellulose) with 10 ml reagent. then placed in a plastic container (30 ml volume) and stirred for 24 hrs using magnetic stirrer [15]. after that the sample was washed with deionized water and dried for 8 hours at 50oc. figure (2) shows the sample after treatment with fenton's reagent. fig. 2. the sample after treatment with fenton's reagent. 3. the treated sample was placed in a test tube and 10 ml of naoh solution was added. 4. the sample was left for 1 hr, and then placed in a plastic container which contains ethyl glycol (38%) and put in freezer for 24 hrs. 5. the sample was removed from the freezer and left for at least one hour at room temperature to melt it. 6. then the sample was centrifuged at 2500 rpm to separate the dissolved fibers from those which undissolved. 7. undissolved fibers were washed with distilled water and weighted to calculate dissolution percent as in eqn. (1). cellulose dissolution% weight of cellulose������ ���������weight of cellulose����� �������� !"#$% &' cellulose������ �������� ∗ 100 …(1) yasmeen salih mahdi al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 107115 (2018) 110 8. the dissolved fibers were injected in 10 % dilute sulphuric acid to form rayon, as shown in figure (3). fig. 3. synthesis of rayon (regenerated cellulose). 3. results and discussion 3.1 cellulose dissolution three parameters were studied in the dissolution process; sodium hydroxide concentration, path cooling temperature and fenton's reaction time. the ranges of these parameters were (4 %-12%) weight percent, two temperatures (-15 and -20) oc and (1-48) hours respectively. two types of samples were used; sample was treated with reagent and a sample without treatment. experiments were repeated four times and average values of cellulose dissolution were taken. 3.1.1 effect of fenton's reaction treatment to study the effect of fenton's reagent use on cellulose dissolution, several values of fenton's reaction time were studied within the range (1-24) hr. fenton's reaction produces radicals which break the hydrogen bonds for cellulose and make it ready to dissolve in naoh solution. from fig. (4) it was concluded that cellulose dissolution increased with increasing time until time 24 hr, beyond which the solubility of cellulose fibers begin to decrease. this is because the structure of cellulose fibers distorted and leads to decrease dissolution of cellulose fibers. the optimum value of cellulose dissolution was 30 wt % which occurred at reaction time 24hr. budtova and navard (2016) studied the dissolution of cellulose fibers for cotton and found that the perfect fenton's reaction time was 18 hr. to give maximum cellulose dissolution of 23%. fig. 4. effect of fenton's reagent duration on cellulose dissolution. 3.1.2 effect of naoh concentration to study the effect of alkaline concentration for cellulose dissolving, four values of concentration were taken (4%, 6 %, 8 % and 12 wt %). two sets of experiments were conducted. in the first set, the samples were treated with fenton's reagent for 24 hr. while in the second set the samples were untreated. fig (5) shows that for both sets at (15oc) , the best value of naoh concentration was 8% which causes cellulose dissolution of 30 wt% for samples which treated with fenton's agent and 23% for samples which untreated. wang (2008) was studied cellulose dissolution for cotton linter (as a cellulose fibers source) using naoh solution with different concentrations and different cooling bath temperatures and found that the best cellulose dissolution percent was 20 wt% when using 9 wt% naoh concentration. yasmeen salih mahdi al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 107115 (2018) 111 fig. 5. percentage of cellulose dissolution at different naoh weight concentrations at temperature 15 ±2oc. the same two sets of experiments were conducted at -20oc. figure(6) shows that the best cellulose dissolution for sample which treated with fenton's reagent was 42% which occurred also at 8% naoh concentration while for untreated sample the maximum cellulose fibers dissolution was 28% this implies that decreasing the temperature to -20oc will enhance the solubility of cellulose in naoh solution. fig. 6. percentage of cellulose dissolution at different naoh weight concentrations at temperature -20 ±2oc. from figures (5and 6), it was concluded that the best naoh concentration for cellulose dissolution process was 8%. furthermore, the samples which treated with fenton's reagent show better dissolution in naoh solution than those which untreated. figure 7 illustrates how the hydrodynamic of hydrate ions was affected by the concentration of ion solution. at low solution concentration, the ions are surrounded by a large amount of water molecules and thus pairs of separated ions are existing. at high solution concentration, the ions will be surrounded by fewer amounts of water molecules resulting in lower hydrodynamic diameter. the cellulose crystallite diameter is 10 nm and inter-sheet distance is of about10 ȧ [17]. at low concentration of naoh, the hydrodynamic diameter is too large to penetrate cellulose crystalline region, while at high naoh concentration the hydration of naoh will be insufficient to break hydrogen bonding which makes the cellulose to mercerize (not dissolved). therefore; there is a certain concentration of naoh solution which is appropriate to penetrate the cellulose and start to dissolution. this value of concentration is called turn point concentration (critical concentration) [18]. in the current study, it was found that the turn point concentration was 8%. this finding is agreement with that found by wang (2008) who found that the turn point concentration of cellulose (cotton linter) was 9%. fig. 7. hydrodynamic diameter of hydrates with respect to naoh solution concentration [19]. 3.1.3 effect of temperature with a view to study the effect of temperature on solubility of cellulose fiber, two values of temperatures were used (-15 oc and -20 oc) depending on previous studies [20] [21]. figure (8) shows that at -20 oc, the best cellulose dissolution for sample which treated with fenton's reagent was 42% and for untreated sample the maximum cellulose fibers dissolution was 28%. while at temperature (-15oc), the cellulose dissolution percent was 30 % for treated sample and 23% for untreated sample. this implies that decreasing temperature to (-20 oc) will enhance the solubility of the cellulose in naoh solution. yasmeen salih mahdi al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 107115 (2018) 112 fig. 8. effect of temperature on cellulose dissolution at 8% alkaline solution. the explanation the effect of temperature on the solubility of cellulose will be in the next section. 3.1.4 effect of urea addition the effect of adding urea to naoh solution on cellulose fibers dissolution was studied, a solution of naoh and urea with proportion (6%naoh and 4% urea) was used to enhance cellulose fibers dissolution or stimulate crystalline polymerization [17].figure (9) shows that at temperature -15oc the maximum cellulose fibers dissolution was 62% for the samples which treated with fenton's reagent and 35% for untreated. figure (10) shows the results of cellulose dissolution at temperature 20oc. for the sample which treated with fenton's reagent the maximum cellulose fibers dissolution was 35% while for an untreated sample was 28%. these results for treated samples indicate that adding urea will increase the solubility from 30% to 62% at (-15oc) while at (-20oc) adding urea will decrease the cellulose fibers dissolution from 42% to 35%. fig. 9. effect of urea addition on cellulose dissolution at temperature 15 ±2oc. fig. 10. effect of urea addition on cellulose dissolution at temperature -20 ±2oc. the cellulose fibers dissolution is a thermodynamic process and can be represented by gibbs free energy equation: ∆g = ∆h – t. ∆s … (1) for cellulose dissolution process (breaking cellulose crystal) by naoh solution without urea, values of entropy and enthalpy change are -2.23 kj /mol k and -495.48 kj /mol respectively. while for the treatment with naoh and urea, values are -0.546 kj /mol k and -61.83 kj /mol respectively [22]. at temperature 258 k (-15oc), ∆g=80.55 kj /mol for treatment without urea and ∆g=79.01 kj /mol for treatment with urea. the decrystallization reaction is exothermic because of the negative value of enthalpy so lower temperature is favorable. figure 11 shows the plot of gibbs free energy verses temperature for dissolution of cellulose by naoh solution with and without urea. the two straight lines intersect at temperature 258k (-15oc). at temperature greater than 258k (-15oc), the treatment with naoh and urea solution has lower ∆g than that without urea which is better for decrystallization reaction. while at temperatures less than 258k (-15oc) naoh without urea has lower ∆g so it is better for decrystallization. in the current study the lowest temperature was 253k (-20oc). yasmeen salih mahdi al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 107115 (2018) 113 fig. 11. gibbs free energy for cellulose dissolution by naoh with and without urea [16]. 4. conclusion based upon the results obtained so far, there is a possibility to dissolve the cellulose which extracted from the date palm fronds using naoh solution method. the more effective parameters in the cellulose fibers dissolution process were: cooling bath temperature, naoh concentration and time of fenton's reagent treatment. the best naoh concentration for cellulose fibers dissolution was 8 wt% at -20oc at which the dissolution of cellulose reaches 42% when the samples were treated with fenton's reagent for 24 hr, while for samples untreated with fenton's reagent the dissolution reaches 28%. adding urea to naoh solution (6%naoh and 4% urea) was found to increase the cellulose dissolution to 62% at temperature -15oc for samples which treated with fenton's reagent for 24 hr. 5. reference [1] t. budtova and p. navard, “cellulose in naoh–water based solvents: a review,” cellulose, vol. 23, no. 1, pp. 5–55, 2016. 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[22] m. kihlman, b. f. medronho, a. l. romano, u. germgård, and b. lindman, “cellulose dissolution in an alkali based solvent: influence of additives and pretreatments,” j. braz. chem. soc., vol. 24, no. 2, pp. 295– 303, 2013. )2018( 107-115، صفحة 2د، العد14دجلة الخوارزمي الهندسية المجلمياسمين صالح مهدي 115 أذابة ألياف السيليلوز في المحاليل القاعدية **عالء كريم محمد* عاصم حسن محمد** ياسمين صالح مهدي* جامعة بغداد قسم الهندسة الكيميائية االحيائية/ كلية الهندسة الخوارزمي/*** ،* الكيمياوية/ الجامعة التقنية الوسطىقسم الصناعات ** معهد التكنولوجيا بغداد/ gmail.com90yasmeensalih@ البريد االلكتروني:* asemh2005@yahoo.com:البريد االلكتروني * alaauniv@yahoo.com:البريد االلكتروني *** الخالصة المزارعمن سعف النخيل (نوع الزهدي) المأخوذ من ةفي هذه الدراسة، تم أستخدام محلول هيدروكسيد الصوديوم ألذابة األلياف السليلوزية المستخلص وزنية ريت التجربة مع تراكيز، يتم تفاعل محلول هيدروكسيد الصوديوم مع ألياف السليلوز في درجات حرارة منخفضة. أجعملية االذابةالعراقية. في درجة مئوية. كان الحد األقصى لذوبانية السليلوز ٢٠ -درجة مئوية و ١٥ -٪) في درجتين حرارية ١٢و ٪٨، ٪٦، ٪٤مختلفة من هيدروكسيد الصوديوم ( ة مئوية. من أجل تعزيزذوبانية ألياف درج٢٠-٪ من هيدروكسيد الصوديوم وفي درجة حرارة ٨٪ نسبة وزنية وقد تم الحصول عليها عند تركيز ٢٣هي ) وكبريتات الحديد الثنائية 4o2h2c) وحامض األوكساليك (2o2hالسليلوز ، تم معالجة النموذج مع كاشف فينتون الذي يتكون من بيروكسيد الهيدروجين ( )4feso درجة تم دراسة ثالثة متغيرات وهي). يتفاعل هذا الكاشف مع ألياف السليلوز لينتج الجذور الحرة التي تزيد من ذوبان السليلوز. في هذه الحالة هرت ) ساعة. وأظ٤٨-١٪) ووقت المعالجة بكاشف فينتون (١٢و ٪٨، ٪٦، ٪٤) درجة مئوية، تركيز هيدروكسيد الصوديوم (٢٠-و ١٥-الحرارة عند ( ٪. في ٨درجة مئوية) وتركيز هيدروكسيد الصوديوم ٢٠-ساعة) ، درجة حرارة ( ٢٤) عند زمن معالجة (٪٤٢النتائج أن أفضل نسبة لذوبانية السليلوزهي ( يوريا) عند ٪ ال٤هيدروكسيد الصوديوم + ٪٦بنسبة ( بوصفه محفزامجموعة أخرى من التجارب تمت إضافة اليوريا إلى محلول هيدروكسيد الصوديوم ٪ ٣٥و٪ للنموذج الذي تم معاملته مع كاشف فنتون ٦٢إلى ز تزداد) درجة مئوية. أظهرت النتائج أن ذوبانية السليلو٢٠-و ١٥-درجتين حرارية هي ( درجة مئوية.١٥-تم الحصول عليها عند درجة حرارة القيمتين لذوبانية السيليلوزلتا للنموذج غير المعالج، وك 1-7 al-khwarizmi engineering journal,vol. 11, no. effect of acetic acid aa2319-t3 al-alloys department (received abstract the present study investigates the effect of sealed anodized aa2319-al-alloys. anodizing treatment was performed in without addition of acetic acid. hydrothermal sealing was carried out in boiling water for each anodized specimen. open circuit potential of the unsealed and sealed anodized measurement for the purpose of starting in scanning polarization diagrams. measurements were performed to assess and sealed anodized aluminum. it was aluminum was sensitive to degree of seal phosphoric acid electrolyte mainly due to their lower anodic and cathodic currents obtained on the sealed anodized aluminum surface corrosion improvement. the present study clearly validates the beneficial role of anodizing baths for the corrosion protection of aa2319 keywords: phosphoric acid, acetic acid 1. introduction aluminum-copper (al-cu) alloys have a low density and high electrical and thermal conductivity [1]. aa2319 (~ 6% cu), composed of an al2cu phase and al-rich areas, is particularly promising due to its high strength and thus it is currently used in aerospace applications [1, 2]. unfortunately, these alloys suffer from poor corrosion resistance, due to their high cu content, and are highly susceptible to water initiated pitting corrosion, potentially leading to fatigue failure [2]. the widely using of chromic acid (c anodizing in the aeronautic industry corrosion resistance of aluminum alloys [ incorporation of cr (vi) and cr (iii) into the oxide gives higher corrosion resistance than that produced by other anodizing processes. since the beginning of the 1990s, the uses of khwarizmi engineering journal,vol. 11, no. 4, p.p. 17 (2015) acid on electrochemical behavior of sealed lloys anodized in phosphoric acid khalid h. rashid department of chemical engineering / university of technology email: alhadidikhalid@yahoo.com (received 26 january 2015 ; accepted 21 june 2015) the present study investigates the effect of acetic acid on corrosion behavior and its potential . anodizing treatment was performed in stagnant phosphoric . hydrothermal sealing was carried out in boiling water for each anodized specimen. open circuit potential of the unsealed and sealed anodized samples was examined using open circuit potential measurement for the purpose of starting in scanning polarization diagrams. the potentiostatic polarization performed to assess corrosion behavior and sealing quality (i.e., degree of it was shown that the potentiostatic anodic and cathodic polarization of anodized aluminum was sensitive to degree of seal, which was more efficient in the case of anodized aluminum acid electrolyte mainly due to their higher corrosion potential and lower corrosion current obtained at sealing exposure time 60 min. this suggests a specific role of the species surface coating, which contributes to the increasing of the performance in terms of . the present study clearly validates the beneficial role of acetic acid protection of aa2319-al-alloys. acetic acid, aluminum alloy 2319, anodizing, polarization technique cu) alloys have a low density and high electrical and thermal 6% cu), composed rich areas, is promising due to its high strength and thus it is currently used in aerospace applications ]. unfortunately, these alloys suffer from poor corrosion resistance, due to their high cu content, and are highly susceptible to waterion, potentially leading to chromic acid (cro3) anodizing in the aeronautic industry is to improve corrosion resistance of aluminum alloys [3]. the incorporation of cr (vi) and cr (iii) into the oxide gives higher corrosion resistance than that produced by other anodizing processes. since the uses of cr (vi) have been restricted in industrial applications their high toxicity. as a consequence, numerous attempts have been made to find less toxic alternatives, but with limited success [ during the last decade, interesting acid (h3po4) anodizing and acid (ch3cooh-h3po4) anodiz to replace cro3 anodizing has increased [ anodizing with phosphoric introduced to obtain thin anodic films approximately (1-5.4 µm resistance for specific structural materials [ even though the fatigue specimens anodized in increased, the corrosion resistance is lower than that of specimens anodized in [10] have proposed a new anodizing procedure involving the addition of acetic acid in phosphoric acid electrolyte, called acetic (ch3cooh-h3po4) anodizing. sometimes used as anodizing electrolyte for al-khwarizmi engineering journal (2015) on electrochemical behavior of sealed acid electrolytes potential of hydrothermally phosphoric acid electrolyte with or . hydrothermal sealing was carried out in boiling water for each anodized specimen. the was examined using open circuit potential otentiostatic polarization technique (i.e., degree of sealing) of the unsealed the potentiostatic anodic and cathodic polarization of anodized anodized aluminum formed in aceticlower corrosion current, generally passes this suggests a specific role of the species of the performance in terms of acetic acid in phosphoric acid technique. in industrial applications due to . as a consequence, numerous attempts have been made to find less toxic alternatives, but with limited success [4, 5]. interesting to phosphoric anodizing and acetic-phosphoric anodizing as alternatives anodizing has increased [6, 7, 8]. phosphoric acid (h3po4) has been introduced to obtain thin anodic films µm) that increase fatigue resistance for specific structural materials [9]. even though the fatigue resistance of the specimens anodized in phosphoric acid is increased, the corrosion resistance is lower than that of specimens anodized in cro3. nazree, et al. proposed a new anodizing procedure involving the addition of acetic acid in phosphoric acid electrolyte, called acetic-phosphoric acid ) anodizing. acetic acid is sometimes used as anodizing electrolyte for khalid h. rashid al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 17 (2015) 2 aluminum alloys due to its ability to form anodic films [11, 12]. however, the use of acetic phosphoric acid mixtures as anodizing electrolytes is poorly reported in the literature. ma song-jiang et al. [13] has been reported that mixed acid solution as anodizing electrolytes can decrease the film dissolution rate, then increase the film formation efficiency and improve the film properties. wahab and derman [14] have investigated the influence of the addition of acetic acid to phosphoric acid electrolyte on anodizing of pure aluminum (99%). yaro and al-asadi [18] have investigated the effect of hydrothermal sealing time on the anodic polarization of anodized aluminum alloy aa5052 in different conditions. the authors showed that the addition of acetic acid reduced by ~20% the steady-state current during film growth at constant voltage. neither of the research groups attempted to investigate corrosion behavior of the anodic films formed in the two solutions [10, 14]. the role of acetic acid in the anodizing bath still remains unclear. the present study aimed for a better understanding of the effect of acetic acid on the corrosion behavior and its potential of hydrothermally sealed anodized aa2319-alalloys. 2. experimental work 2.1. materials and conditions the substance used was a 2319 t3 aluminum alloys. the average chemical composition of the alloy is given in table (1). the dimensions of samples are 125 × 8 × 1.6 mm plates machined from an aa2319 t3 rolled plate. aluminum samples before anodizing and corrosion tests were abraded in sequence on 220, 320, 400 and 600 grades of emery paper under running tap water on a metasern hand grinder tray washed with tap water followed by distilled water, dried with a clean tissue, degreased by immersing them in acetone & benzene, then dried with paper tissue and kept in a dissector over a silica gel bed. the treatment of anodizing was performed in a 40 g l−1 (0.41 m) phosphoric acid (h3po4) solution in the presence or absence of 80 g l−1 (1.33 m) acetic acid (ch3cooh). experiments of anodizing were carried out at a constant cell voltage of 15 v for 30 min. the operating temperature was maintained within 35 ± 1 °c by a thermometer. sealing was carried out in (di) water at a temperature of 100 °c. table 1, chemical composition of 2319 t3 aluminum alloy (% wt). si fe cu mn mg zn ti al 0.20 0.30 6.3 0.30 0.02 0.10 0.15 92.63 min 2.2. polarization measurements the polarization measurements were carried out in a corrosion cell (three-electrode electrochemical cell) which is contain the auxiliary electrode, reference electrode and working electrode. it contained a platinum foil type (tacussel pt-f05/30) as auxiliary electrode (area of ~ 30 cm2), a saturated calomel reference electrode (sce) type (tacussel type c4) bridged by a laggin-haber probe. the reference electrode, which was bridged by a luggin haber capillary was set at about the optimum value of 1 mm to minimize the experimental error. the aa2319 t3 samples as working electrode (exposed area of 10 cm2 and other side and thickness of the samples were coated with the epoxy to prevent exposure to the solution), held by aluminum jigs in order to hold the samples, it was coated with rubber tube to hold it stable in the cell and prevent the short circuit contact. open circuit potential (ocp) measurments were carried out and measured from off-circuit potential-immersion time measurments [17]. the corrosion cell parts were joined to each other, and then connected to potentiostat, ammeter and voltmeter as described in figure 1 and polarization was carried out in electrochemical cell with electrical circuit shown in figure 2. the auxiliary electrode was a platinum electrode of (2.7×11 cm), held by plastic plate set directly opposite to the working electrode. the potentiostat device using in this article is modern computerize type wenking m lab device of bank electronic, germany. the scan rate is 10 mv/min. reference electrode calibration was carried out by 30 % kcl solution for activation. the polarization figures were plotted under potentiostatic conditions at the actual corrosion potential. the electrochemical cell was maintained at 25 °c and open to surrounding. the open circuit potential (ocp) of the unsealed and sealed anodized aluminum samples were measured after 1.5 h of immersion at room temperature in a 0.5 m na2so4 solution and 3.5 m nacl solution respectively. sodium sulfate was chosen toward aluminum and aluminum alloys khalid h. rashid al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 17 (2015) 3 due to its property (low corrosiveness). the polarization behavior of sealed and unsealed anodized samples was investigated in 3.5 m nacl solution, at different sealing times. anodizing treatment was performed in stagnant phosphoric acid electrolyte with acetic phosphoric acid or without (h3po4) addition of acetic acid. hydrothermal sealing was carried out in boiling deionized (di) water for each anodized sample. the corrosion behavior of the hydrothermally sealed and unsealed anodic films was carried out using potentiostatic polarization technique. the sensitivity of potentiostatic polarization makes it a successful technique for assessing the sealing quality and corrosion parameters of the anodic films from polarization curves [7, 15 and 16]. stagnate solutions of chloride containing solutions at 25ºc have been investigated using polarization technique was carried out to characterize the properties of the unsealed and sealed anodic films. the electrochemical parameters obtained from a fitting procedure of the polarization diagrams allowed the corrosion behavior difference of the two samples to be shown and discussed. the corrosion potential results were correlated with the open circuit potential (ocp). fig. 1. wenking m lab device. fig. 2. schematic diagram of corrosion cell used in polarization. 3. results and discussion the corrosion potential diagrams obtained after different sealing times (5, 15, 30, 45 and 60 min.) for the hydrothermally sealed anodized samples formed in phosphoric acid have the different shape as those obtained for the samples formed in acetic-phosphoric acid. figure 3 compares the corrosion potential (ecorr) values for both systems. it appears that for the anodic films formed in acetic-phosphoric acid, the variation is linear, whereas for the films in phosphoric acid it is not, and the ecorr values always remain lower than those obtained with acetic-phosphoric acid. for the shortest sealing time, ecorr was < 850 mv, which reveal the low level of the anodic film sealing. sealing times of > 30 min. are necessary to obtain acceptable sealing of the anodic film. these results show that the lower part of the porous structure of the anodic film formed in phosphoric acid was not perfectly sealed after 30 min. of reaction, corroborating the trends deduced from electrochemical potential results. the corrosion potential results stress that film sealing differs, depending on the initial anodic film. a better sealing efficiency (higher ecorr) was obtained for the anodic films formed in the presence of acetic acid. then, to investigate the influence of sealing quality on the corrosion behavior of unsealed and sealed anodized aa2319 samples, the open circuit potential of the unsealed and sealed anodic films formed in phosphoric acid and acetic-phosphoric acid was investigated by plotting the open circuit potential diagrams versus exposure time (from 0 to 1.5 h) in 0.5 m na2so4 and 3.5 m nacl solutions respectively is presented in figures 4, 5 & 7. fig. 3. corrosion potential values vs. sealing time for the sealed anodized aluminum aa2319 in phosphoric acid and acetic-phosphoric acid solutions in 3.5 m nacl solution at 25 ºc. thermometer a.e: auxiliary electrode r.e: reference electrode sce w.e: working electrode potentiosta hot plate a.e r.e w.e v a v r w a a 0 10 20 30 40 50 60 70 sealing time (min.) -900 -850 -800 -750 -700 -650 -600 -550 -500 -450 c o rr o si o n p o te nt ia l ( m v ) v s. s c e phosphoric acid acetic-phosphoric acid khalid h. rashid al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 17 (2015) 4 0 10 20 30 40 50 60 70 80 90 100 immersion time (min.) -1600 -1500 -1400 -1300 -1200 -1100 -1000 -900 -800 p ot en tia l ( m v ) vs . s c e phosphoric acid acetic-phosphoric acid fig. 4. open circuit potential of unsealed anodized aluminum aa2319 in phosphoric acid and aceticphosphoric acid solutions in 0.5 m na2so4 solution at 25 ºc as a function of immersion time. -20 0 20 40 60 80 100 immersion time (min.) -1150 -1100 -1050 -1000 -950 -900 -850 -800 -750 p ot en tia l ( m v ) vs . s c e 5 min. sealing time 15 min.sealing time 30 min.sealing time 45 min.sealing time 60 min.sealing time fig. 5. open circuit potential of sealed anodized aluminum aa2319 in phosphoric acid solution after different sealing times in 3.5 m nacl solution at 25 ºc as a function of immersion time. -0.3 -0.2 -0.1 0.0 0.1 0.2 0.3 0.4 0.5 log current density (ma/cm2) -1150 -1100 -1050 -1000 -950 -900 -850 -800 -750 -700 p ot en tia l ( m v ) vs . s c e 5 min. sealing time 15 min. sealing time 30 min. sealing time 45 min. sealing time 60 min. sealing time unsealed fig. 6. potentiostatic polarization curves of unsealed and sealed anodized aluminum aa2319 in phosphoric acid solution after different sealing times in 3.5 m nacl solution at 25 ºc. fig. 7. open circuit potential of sealed anodized aluminum aa2319 in acetic-phosphoric acid solution after different sealing times in 3.5 m nacl solution at 25 ºc as a function of immersion time. -20 0 20 40 60 80 100 immersion time (min.) -1100 -1000 -900 -800 -700 -600 -500 -400 p ot e n tia l ( m v ) vs .s c e 5 m in.sealing time 15 min.sealing time 30 min.sealing time 45 min.sealing time 60 min.sealing time khalid h. rashid al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 17 (2015) 5 -0.25 -0.20 -0.15 -0.10 -0.05 0.00 0.05 0.10 0.15 0.20 0.25 0.30 log current density ( ma/cm2 ) -1100 -1000 -900 -800 -700 -600 -500 -400 -300 p ot e n tia l ( m v ) vs . s c e 5 min. sealing time 15 min. sealing time 30 min. sealing time 45 min. sealing time 60 min. sealing time unsealed fig. 8. potentiostatic polarization curves of unsealed and sealed anodized aluminum aa2319 in aceticphosphoric acid solution after different sealing times in 3.5 m nacl solution at 25 ºc. 3.1. potentiostatic polarization measurements the potentiostatic polarization behavior of unsealed and hydrothermally sealed aluminum aa2319 anodized in phosphoric acid and aceticphosphoric acid in 3.5 m nacl solution at 25 ºc is presented in figure 6 and figure 8 respectively. figures 6 and 8 show the effect of acetic acid on corrosion behavior of sealed aa2319 anodized in phosphoric acid electrolyte and aceticphosphoric acid electrolyte after different sealing times in 3.5 m nacl solution at 25 ºc, on the relationship between current density and potential of aluminum alloy aa2319. in these figures it can be seen that: 1. the obtained corrosion potential (ecorr) values for sealed anodized aluminum alloy 2319 are quite sensitive to the sealing of the anodized aluminum after different sealing exposure times shift to more positive (more noble) direction compared with unsealed samples due to sharp anodic and cathodic kinetic change accompanied reduction of corrosion current densities (icorr) because the initial principle purpose of sealing is to further improve the corrosion resistance of anodized aluminum. this is also in close agreement with the research done by yaro and al-asadi [18]. 2. the cathodic reactions behavior of the polarization curves shows over a wide potential range that in the case of sealed anodized samples, in phosphoric acid the sealed anodized surface is more diffusion (mass transfer) to the predominant oxygen reduction reaction (as the principle rate limiting reaction) than the unsealed surface and in acetic-phosphoric acid the sealed anodized surface is more activation to the predominant hydrogen evolution reaction than the unsealed surface, i.e., the sealed anodized surface has an electronic resistivity of order [19]: h3po4 sealed anodized > unsealed one ch3cooh-h3po4 sealed anodized > unsealed one ch3cooh-h3po4 sealed anodized > h3po4 sealed anodized 3. at anodic and cathodic sites on the sealed anodized surface, suppressing the kinetic of anodic and cathodic polarization curves is more pronounced aluminum alloy 2319 anodized in acetic-phosphoric acids electrolyte and the anodic and cathodic current densities for sealed anodized samples reduced high value particularly at sealing exposure time 60 min than unsealed anodized samples. 4. conclusions the sealing quality (i.e., degree of sealing) and the corrosion protection of aa2319 t3 anodized in phosphoric acid in absence and presence of acetic acid were investigated by potentiostatic polarization technique. the following conclusions might be withdrown from this investigation: 1. electrochemical polarization measurements are sensitive to the presence of anodized aluminum surface films. 2. anodizing of aa2319 t3 in presence of acetic acid led to the formation of anodic films with higher corrosion potential (i.e., improvement of the corrosion resistance of anodized aluminum surface) and lower corrosion current density than those obtained in phosphoric acid. 3. the sealing quality was better for the anodized samples formed in acetic-phosphoric acid than in phosphoric acid in agreement with the higher corrosion potential with reduction of anodic and cathodic currents of the anodized samples formed in acetic-phosphoric acid. 4. the sealed anodized samples formed in aceticphosphoric acid are significantly more potential to corrosion than the sealed anodized samples formed in phosphoric acid. 5. the corrosion current densities for unsealed samples are found to be higher than khalid h. rashid al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 17 (2015) 6 hydrothermally sealed anodized samples for both systems and the corrosion potential for hydrothermally sealed anodized samples are shifted more positive than unsealed samples for both systems 5. references 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[15] v. marzocchi, l. iglesias-rubianes, g. e. thompson and f. bellucci, corrosion reviews, j., vol. 25, no. 461, 2007. [16] v. lopez, m. j. bartolome, e. escudero, e. otero and j.a. gonzalez, electrochem. soc., j., vol. 153, no. 75, 2006. [17] r. d. james and j. a. frank, "effect of measurement and instrumentation errors on potential readings", corrosion, vol. 11, no. 1294, pp.1-10, nace, 2001. [18] a. s. yaro and a. m. a. al-asadi, "anodic polarazation of anodized aluminum alloy 5052", m.sc. thesis, university of baghdad, iraq, 2004. [19] n.l. sukiman, x. zhou, n. birbilis and a. e. hughes, "durability and corrosion of aluminum and its alloys: overview, property space, techniques and developments", (http://dx.doi.org/10.5772/53752), 2013. � � ���� ر��� ��� ���� 4، ا ��د�11��� ا ��ارز�� ا ������ ا ،2015( 17( 7 �� �2٢٣١٩, ���1 ا ���0 /�. ا #��ك ا �,و+� ��وي ()�دة و %$ �#���ت �!� � ا ���م �9 ��� �8 ���1 ا �����ر07 ا( � %,و �%�� � � ���� ر��� �� ا������ ا������و��� / ���ا�#�"!� ا� ����� email: alhadidikhalid@yahoo.com �� ا �: �������3 ا>�����م ا� :6789 ھ4ا ا�3+2 �1 درا�� ا� .-�, �+�"* ا�(%�) '%& �%�ك و�aa2319 6%=ام ا���ء ا���) �.? ��"��. ا��.a�دة ا��( �"� ا�� ) l%m ا����"�ت(�1 إa#�ز '�%�� ا�( � . �1 إ�,اء '�%�� ا>a�دة 67 ا��+%�ل ا>��� ,و�� 6 ا���h9 �+�"* ا�g��g�ر�) ?���د أو ?�ون إ�b �7�c"* ا�(%�) ��� ا��اr,ة ا�. ?�p�,q ا���ء ا��=�a 8�� 6%�ذج ".a�د s+7 اء,��( �"� ا����"�� ?.� (�ام ���س ��� ا��اr,ة ا�� g��b �%���ذج ا��.a�دة ا��( �"� و�m, �1 إ �����y�م ) أي در�� ا�( �(و��دة ا�( � ا� :�189 إ� (�ام ���p1 ا>� �qpب �%#�� ا���h��! � h9 �%�ك . ا�� g��b �=,ض ا��3أ 67 "��qq)" vت ا>� �qpب ,�m دة�a.م ا�ا�ا���م وا��( � )���"������ و1 .-, ?�ر�� ا�( � . �b za�9 د�a.م ا�������y� h9��"h ا�� �h�31 [r أن '�%�� ا>� �qpب ا>a�دي وا���-�دي ا� ��� 6 ا>'%& �ا� :9%ا�(%�) ?^�8 رa ]�r �#� �#��ھ� و za�9 أ�g9 ,\9ءة ���b 67 ا>�����م ا��.a�د ا�� ��ن 67 ا��+%�ل ا>��� ,و�� 6 �+�"* ا�g��g�ر�) �٦٠��v ?�,ور أ�8 ��1رات أa�د�� و�9-�د�� z%ab '�� ز"h 1!,ض ` � ?!�"� ، ا� :89وا>�8 ��1ر �p��ھ4ا �p ,ح �%�ور ا��+�د �%���lr '%& أ9��ء . د vc ا��ظ��g ا����gة �+�"* أ-z 3 ا��را�� ا�+���� ?^�8 وا. ا� :89 و��� fa,>داء "h ا1+��vq�67 h ا>�����م ا��.a�د ا��( �م "��"� e ا�4ي ���ھ� ����3 ا>�����م ا� :89ا�(%�) 67 أb�اض ا>a�دة �+�"* ا�g��g�ر�) �+���� �aa2319. 40-50طلال وايمان ومودة al-khwarizmi engineering journal,vol. 13, no. 1, p.p. design and implementation iman salih karem mawada *,**,***department of electromechanical engineering /university of technology *email: ***email: (received 21 august https://doi.org/10.22153/kej.2017.01.002 abstract this paper presents mechanical and electrical design scara (selective compliment assembly robot arm),with two rotations and one translation used for welding applications.the design process also included the controller design controller) as well as selection of mechanical and electrical component components in iraq with reasonable costs. the robot mentioned is fully automated using programmable logic controller plc(zelio type sr3-b261bd),with 16inputs and 10 outputs. different automatic motions with high efficiency withouterror,where the two links bushed down for doing the task in a desired trajectory motion by programming the keywords: dof, fbd, plc, scararobot. 1. introduction applying autonomy is a comparatively youthful domain of current technology that crosses conventional engineering limits. comprehension the multifaceted nature of robots and their implementations requirements of electrical engineering, mechanical designing, frameworks, modern building, software engineering, mathematics and economics. the robot is a reprogrammable multifunctional controller designed to handling a material, accessories, devices, or particular gadgets through variable programmed motions for the fulfillment for a set of assignments [1]. the robots display significantly convoluted electromechanical systems with common collaborations of robot mechanics and drives, at configuration of which the mechatronic methodology ought to be taken into consideration [2]. khwarizmi engineering journal,vol. 13, no. 1, p.p. 4050 (2017) implementation for 3-dof scara robot based plc karem* talal a. jabbar a.wahab** mawadah jlaa yahyh*** electromechanical engineering /university of technology *email: dr_esk_71@yahoo .com ***email:electromechanical19@yahoo.com august 2016; accepted 22 january 2017) https://doi.org/10.22153/kej.2017.01.002 ectrical design, and implementation process of industrial robot scara (selective compliment assembly robot arm),with two rotations and one translation used for welding applications.the design process also included the controller design which was based on plc(programmable logic on of mechanical and electrical components.the challenge was to use components in iraq with reasonable costs. the robot mentioned is fully automated using programmable logic controller ),with 16inputs and 10 outputs. the plc was implemented in fbd logic to obtain three different automatic motions with high efficiency withouterror,where the two links can stop in a certain points and link 3 bushed down for doing the task in a desired trajectory motion by programming the plccontroller. applying autonomy is a comparatively of current technology that crosses conventional engineering limits. the multifaceted nature of robots learning ering, mechanical designing, modern building, software robot is a reprogrammable multifunctional material, s, or particular gadgets through fulfillment the robots display significantly convoluted electromechanical systems with common collaborations of robot mechanics and drives, at configuration of which ought to be taken an industrial robot is a programmable, multi practical controller designed to re parts, apparatuses, or special gadgets through variable modified movements for the of a set of tasks [3]. plc is simply a special computer device used for industrial control systems. that and an output interface, controlled by a program designed by a computer; it is used for for electromechanical automated process this contains major components processor unit, power supply, programming device, program and data memory, input and output interface and communications interface as shown in figure(1). [4] based plc ** electromechanical engineering /university of technology and implementation process of industrial robot, 3-dof type scara (selective compliment assembly robot arm),with two rotations and one translation used for welding plc(programmable logic .the challenge was to use the available components in iraq with reasonable costs. the robot mentioned is fully automated using programmable logic controller the plc was implemented in fbd logic to obtain three stop in a certain points and link 3 an industrial robot is a programmable, multimove materials, parts, apparatuses, or special gadgets through variable modified movements for the fulfillment is simply a special computer device used that had an input and an output interface, controlled by a simulation a computer; it is used for for process. components processor unit, power supply, programming device, program and data memory, input and output interface and communications interface as shown in figure(1). pdf created with pdffactory trial version www.pdffactory.com https://doi.org/10.22153/kej.2017.01.002 mailto:electromechanical19@yahoo.com https://doi.org/10.22153/kej.2017.01.002 http://www.pdffactory.com http://www.pdffactory.com iman salih karem al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 4050 (2017) 41 fig. 1. the plc system [4]. there are several literatures are available to present research, pouyaand kourosh,(2012) [5] presented, hypotheticl prototype model, simulated and optimized of a 3 dof industrial scara robot with pid controller after optimization with genetic algorithm. mohammad and mahdi ,(2012) [6]a trditional pd controller was used then a comparison method with a neural network controller system to reach the exact position control and motion characteristics of scara arm. firas and ahmed , (2013) [7] proposed a control system to the four degree of freedom (4dof) feedback instruments ivax scara robot manipulator using field programmable gate array(fpga) kit to implemented the inverse kinematic calculations processing. jian and wei, (2013) [8] studied four degrees of freedom scara robot kinematics modeling, using the robotics toolbox forward kinematics of the robot inverse kinematics simulation in the matlab environment. through simulation the observed movement of each joint scara robotic state verification the proposed modeling was corrected to reach the desirable goal by enter the desirable joint angles, and the system output end of the robotic is to reach the space coordinates. sudhaet al., (2013) [9] concentrated on the construction of a robotic arm or a manipulator with scara configuration. the manipulator consists of two revolute joints are rotating joints which create rotation about their axis fitted with two dc motor are interfaced with the atmega 16 microcontroller board using a l293d ic, and one prismatic joint. yousif, (2013) [10] focused in this research on the scara robot which had four degrees of freedom (dofs), with three (shoulder, elbow, wrist) controlling by servo motors and one by pneumatics. it is realized by a 3d hypothetical reality (vr) modeling, which builds and receives instruction through a matlab/simulink in version r2012a, develops an anfis (adaptive neuro fuzzy inference strategy) control scheme for scara robot parameters. zelun et al., (2013) [11] proposed the design of a hardware structure and software of 3-dof industrial spot welding robot, the robot controlled by the plc. panchanand and biswal, (2014) [12] presented a structure of artificial neural network (ann) pattern to find the inverse kinematics solution of a 4dof scara arm. morteza et al., (2014) [13] presented mechanical design of an educational manipulator of industrial scara robot, called fumscara, the designing process contianed, designing of joint, link design, pid controller design and chosen of mechanical and electrical hardware, a critical trajectory in robot’s workspace is traced. nitesh et al., (2014) [14] presented dynamic model of 3-dof scara robot manipulator based on lagrange euler formulation using mamdani based fuzzy controller overcome the drawbacks of conventional pid controller. subhashini et al., (2014) [15] presented sacra robot model and the simulation used unigraphics cad software for deburring operation of circular elements. a complete mathematical modeling was pregnancies out for kinematics and equations are derived using the denavit-hartenberg notation. in this paper a designing process and implementation of an industrial robotic arm of 3dof type scara (selective compliant assembly robot arm) with two rotations and one translation link used for welding applications. the robot mentioned is fully automated using programmable logic controller plc based fbd language to obtain three different automatic motions. pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com iman salih karem al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 4050 (2017) 42 2. robot kinematics the scara robot has three dof.a schematic diagram assigning all the joint axes is represented in figure (2), joint 1 and joint 2 are rotations about z-axis and joint 3is translation vertical.the three dof manipulator kinematic parameters are derived using denavithartemberg formulation shown in table (1) fig. 2. frames of manipulator. table 1, denavit-hartenberg parameters . axis no. i twist angles αi-1 link length ai-1 link offset di joint angles θi 1 0 0 � θ1 2 0 �� 0 θ2 3 0 �� − 0 the forward kinematics include all values of the link transformations that can be multiplied together to find the single transformation from the base, frame (0) to the tip of endeffector frame (3). ����������������� = ��� = ��� � � � � �� ��� =���� ��� ��� ����� ��� ��� ����� ��� ��� ��0 0 0 1 � = ��� −�� 0 0�� �� 0 00 0 1 ��0 0 0 1 �*��� −�� 0 ���� �� 1 00 0 0 00 0 0 1 �* �1 0 0 ��0 1 0 00 0 1 −��0 0 0 1 � = � ��� − ��� −���� − ���� 0 �������� + ���� −��� + ��� 0 ����0 0 1 ��0 0 0 1 � ∗ �1 0 0 ��0 1 0 00 0 1 −��0 0 0 1 � = ���� −��� 0 ����� + ������� ��� 0 ����� + ����0 0 1 −�� + ��0 0 0 1 � ���= ���,���=���,���= 0,���=−���,���=���,��� = 0,��� = 0,���= 0,��� =1 �� = ����� + ���� ...(3.1) �� = ����� + ���� ...(3.2) �� = �� − �� ...(3.3) in this papers, algebraic solution approach was used for deriving the inverse kinematics solution that is to determine the value of angle (θ1), (θ2) and distance (d3)as in[16]. θ2 = a tan2 (�1 − ��������������������� �� , �������������������� ) ...(3.4) θ1 = a tan2 (-p�, p�) ± (a tan2 (�p�� + p�� − (s�l�)�,s�l�) ...(3.5) �� = �� − �� ...(3.6) we can find the linear and angular velocity of end-effector by computing the basic jacobian[16]. ��⃗���⃗ � = [ �(�) ]. ⎣⎢⎢⎢ ⎡ ��̇� �......��̇ ̇ ⎦⎥⎥⎥ ⎤ ⎣⎢⎢⎢ ⎡ ��̇� �......��̇ ̇ ⎦⎥⎥⎥ ⎤ = [ � ��] . ��⃗���⃗ �, �(�) = ⎣⎢⎢ ⎢⎢⎡ s��� 0 0 c��� + �� �� 00 0 −10 0 00 0 01 1 0 ⎦⎥⎥ ⎥⎥⎤ …(3.22) 3. scara robot design process scara manipulator is a nonlinear and time variant system, the applied controllers are necessary to have variation capability where linear models are inadequate to complete high pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com iman salih karem al-khwarizmi engineering journal, vol. 13, no. accuracy and various performance operations [17]. to fulfill research aims are divided the design process into mechanical and electrical parts. 3.1. design of mechanical parts the initial concept of robotic design included the mechanical equipments. this section explain fig b. joints: two revolute joints square solid section, manufactured by milling machine and fig c. toothed pulleys: the various three types are used in the current work. vary in diameter, d. belt: belt drives are widely used in many industries for power transmission since they are cheap and easy to maintain. the main khwarizmi engineering journal, vol. 13, no. 2, p.p. 43 accuracy and various performance operations to fulfill research aims are divided the design process into mechanical and electrical parts. the initial concept of robotic design included the mechanical equipments. this section explain the construction of each part in the scara robot model .the test specification are given in appendix (a). a. links: two links as a manipulator arm square hollow section bar.the center to center distance of the link 1 is (470) mm, and the center to center distance of the link 2 is (335) mm, as shown in figure (3). fig. 3. link form stainless steel. two revolute joints square solid by milling machine and drilling it from the center to connect together to evaluate links as shown in figure ( fig. 4. joint connect the arm. the various three types are used in the current work. vary in diameter, tooth shape, width of the gear and tooth size shown in figure (5). fig. 5. the toothed pulleys. belt drives are widely used in many industries for power transmission since they are cheap and easy to maintain. the main purpose of belt drives is to transfer power between machines. , p.p. 4050 (2017) the construction of each part in the scara robot model .the test specification are given in two links as a manipulator arm square hollow section bar.the center to center distance of the link 1 is (470) mm, and the distance of the link 2 is (335) drilling it from the center to connect together shown in figure (4). the gear and tooth sizes purpose of belt drives is to transfer power pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com iman salih karem al-khwarizmi engineering journal, vol. 13, no. e. ball bearing: the bearing is a machine element that constrains the relative motion to only the desired motion, and reduces friction between moving parts. used 6200rs red rubber sealed as shown in figure (6) f. tool catch: an angle iron with a flat metal rod that has been folded to a 90-degree angle along its length, resulting in an l-shaped piece. linkage with the end of the second link by bolt, to fixation the tool of different tasks as shown in figure (7). fig. 6. ball bearing. fig. 7. tool catch. g. base box structure: designed and implemented box to put and install the motors with photoelectric, and solenoid valve. the box covered by a plate of aluminum is shown in figure (8). khwarizmi engineering journal, vol. 13, no. 2, p.p. 44 : the bearing is a machine tive motion to only the desired motion, and reduces friction between moving parts. used 6200rs red : an angle iron with a flat metal degree angle shaped piece. linkage with the end of the second link by bolt, to fixation the tool of different tasks as designed and the motors with photoelectric, and solenoid valve. the box covered by a plate of aluminum is shown fig. 8. box from iron and covered by aluminum 3.2 the electrical parts the electrical parts for operation the scara robot are included the following devices: a. photoelectric sensor: used photoelectric type retro reflective and ben5m power supply 24-240vac ± 10% 50/60hz and infrared led source selectable light on or dark on by switch. b. plugs and sockets: used two types (ebm10cf00)to connect between scara model and control panel.it can be them to facilitate transmitted it. c. power supply: a power supply model mdr 100-24is an electronic device that supplies electric energy to an electrical load one form of electrical energy to another. a power input receives energy from the energy source, and a power output that transfers energy to the load. d. circuit breaker: is one of the most important safety mechanisms, these simple machines cut the power when any problem occurs. e. relay: relays are a remote control electrical switch that can be switched using low cu to control a high current load and used in many applications, used type[ rxm4ab1bd] from schneider electric f. inverter: used to change the speed of electric motor called ac drive.it is used type n700e operating by power 220 volt. g. solenoid: consists of a coil of wire with an iron plunger that is allowed to move through , p.p. 4050 (2017) box from iron and covered by aluminum. the electrical parts for operation the scara included the following devices: hotoelectric type retro reflective and ben5m-mfr model 10% 50/60hz and infrared led source selectable light on or dark used two types (ebm10cf00)to connect between scara model and control panel.it can beseparated transmitted it. a power supply model mdr24is an electronic device that supplies electrical load. convert one form of electrical energy to another. a power input receives energy from the energy r output that transfers is one of the most important safety mechanisms, these simple machines cut the power when any problem occurs. relays are a remote control electrical switch that can be switched using low current to control a high current load and used in many applications, used type[ rxm4ab1bd] from used to change the speed of electric motor called ac drive.it is used type n700e a coil of wire with an iron plunger that is allowed to move through pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com iman salih karem al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 4050 (2017) 45 the center of the coil. an electric current through the coil creates a magnetic field. the magnetic field exerts a force on the plunger. h. prismatic: used standard cylinders from festo type dsnu-20-2 with maximum pressure 10 bar made of stainless steel and the bearing and end caps made of wrought aluminum alloy. i. air compressor:theeinhell air compressor is a device that converts power into potential energy stored in compressed air that mean supplies the system with compressed air. j. motors: used for driving the links of the robot. the torque of motors provides high starting torque and sloping characteristics. the two motors have 100 watt and 2800 rpm were used in the current work. k. controlling robotic arm:zelio has analog and discrete i/o, 16 input ports, which are can be set as 16 discrete inputs or 10 discrete inputs with 6 analog inputs and 10 ports of discrete output. plc made in schneider electric type sr3-b261bd operating by power 24vdc. connected to pc by serial port in order to use the software program( fbd language),the main advantage is that programs written in function block easy to follow solely follow the trajectory. l. cable tray:used the cable tray made from plastic pvc light weight, easy installation, corrosion resistance and channel slotted track. 4. control system design based plc the software implementation of a scara robot used fbd is a graphical language that lets users simply depict complex steps by easily linking together function blocks, like drawing a circuit diagram with the help of a graphical.[18] this language is similar to linking a diagram more than ladder code. with fbd the blocks are “cabled” together sequently to follow easily. the same instructions as ladder utilize, but visually is more understandable to a viewer than relay logic. the main advantage is that programs written in function block easy to follow solely follow the trajectory[19]. used zelio software and fbd languages uses logic functions in the block diagrams to implement in the controller scara robot model.figure(9) depicts this programming language, where the left side is the system input, and the right side is the system output. moreover checks all parts collecting together suitably and the control panel connecting wires correctly and safely as shown in figure (10).the detailed control system can be illustrated as the flowchart given in figure (11). fig. 9. the programming of zelio. fig. 10. control panal system for scara robot 5. experimental work the robot's mechanical and electrical parts are combined as in figure (12) to run and implement three experimental works to obtain three trajectory motions anti clock wise. the schematic block diagram for overall system illustrated in figure (13) the two links were stopped in certain points and link3 bushed down for doing the task in a desired trajectory motion. the performance of a robot was tested in test trajectory from the simulation results based on inverse kinematic equations to get theta valus using matlab softwer for each experimental. pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com iman salih karem al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 4050 (2017) 46 a. first experimental the motion of the two links was programmed for the theta from θ� = 0°to θ�� = 150°with the same time . 16 theta values were chosen in the 16 axes ,figure (14) depicts the desired first path from starting point to the destination point, by these set values, found that in softwares matlab.a robot manipulator to move its trajectory at a constant velocity in this experimental θ = 0° −150°as identified in the program of plc,see figure (15), each point(red points) describes the position of the end effector of the robot.the two links move in the same theta and make an arc like that in figure (14) . fig. 11. flowchart of controller design for scara robot. fig. 12. final scara industrial robot. fig. 13. the schematic block diagram for overall system. fig. 14. tthe desired first path. pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com iman salih karem al-khwarizmi engineering journal, vol. 13, no. fig. 15. the first practical (actual) motion b. second experimental chose 11 theta values in the 11 axes to creat a disiered path as shown in the figure (16 a).practically the two links moved together from 0° to 90° the angle between them equal zero as shown in figure (16-b),then the link1 stopped just link 2 moves made an angle between links increase 10 degree for each new position depended on controller program plc. each point describes the position of the end effector as shown in figure (16) . (a) khwarizmi engineering journal, vol. 13, no. 2, p.p. 47 (actual) motion. chose 11 theta values in the 11 axes to creat a disiered path as shown in the figure (16a).practically the two links moved together from 0° to 90° the angle between them equal zero as b),then the link1 stopped just an angle between links increase 10 degree for each new position depended on controller program plc. each point describes the position of the end effector as shown (b) (c) fig. 16. ( a) the desired second path.(b&c) the second practical motion c. third experimental in this motion different 11 theta values0 ����,� = 50 in the 11 axes were fed into matlab softwere program to creat the desired path as shon in figure (17-a).prracticaly identify the same value of theta in plc program to obtain the trajectory actual motion ,so the links moves together as shown in figure (17-b) after that the l�movedandl�stopped to a chave the trajectory motion as shown in the figure (17 (a) end position initial position , p.p. 4050 (2017) a) the desired second path.(b&c) the in this motion different 11 theta values��,� = in the 11 axes were fed into matlab softwere program to creat the desired path a).prracticaly identify the same value of theta in plc program to obtain the trajectory actual motion ,so the links moves b) after that the to a chave the trajectory -c) end position pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com iman salih karem al-khwarizmi engineering journal, vol. 13, no. (b) (c) fig. 17. (a) the path for the third motion in matlab (b&c) the third practical motion. 6. conclusions and discussion in this paper,a special steps in design process are done for 3dof scara robotic arm .a three trajectory motion achieved firstly select the desired trajectory path based on the inverse kinematic analysis and using a softwere matlab program to draw the path. scara robot is a nonlinear and time invariant system .to overcome the difficulty and limitation of traditional controller,the plc is applied which has running test before connection with robot and it can be given capability to complete the performance operation with high accuracy.the proposed robot used plc for controlling the system runs faster, with high efficiency ,without error where the desired trajectory equal the actual path because the selected angles which were obtained from inverse kinematic identifiy in the plc then the running process gave the same position to the simulate path which hade draw in matlab. moreover plc has a short production cycle and it can be obtain a new trajectory motion by only changing the program of (zelio plc). the implemented scara robot can be used for welding processes and other applications like pick and place, cutting and drilling by just replacing the tool. end position initial position khwarizmi engineering journal, vol. 13, no. 2, p.p. 48 a) the path for the third motion in in this paper,a special steps in design process dof scara robotic arm .a three trajectory motion achieved firstly select the desired trajectory path based on the inverse kinematic analysis and using a softwere matlab scara robot is a nonlinear and time invariant system .to overcome the difficulty and limitation of traditional controller,the plc is applied which has running test before connection with robot and it can be given capability to complete the nce operation with high accuracy.the proposed robot used plc for controlling the system runs faster, with high efficiency ,without error where the desired trajectory equal the actual path because the selected angles which were atic identifiy in the plc then the running process gave the same position to the simulate path which hade draw in matlab. moreover plc has a short production cycle and it can be obtain a new trajectory motion by only changing the program of (zelio plc). the implemented scara robot can be used for welding processes and other applications like pick and place, cutting and drilling by just 7. references [1] markw.s,seth h. ,andmathukumalli “robot dynamics and contro john wiley & sons, inc. 2008. [2] viliam f.,františek ď.,andróbertü.,“analysis of robotic system motioninsimmechanicsandmatlab gui environment” intech, 2014. [3] alavudeen a., venkateshwaran n., “computer integrated manufacturing ”, phi learning private limited [4] william b., “programmable logic controls”, book 4�� edition, newnes 2006. [5] pouyaj.andkouroshh.s.,“robotmanipulators: modeling, simulationandoptimalmulti variable control,”appl. mech. mater., vol.232, pp.383–387, 2012. [6] mohammada. a. andmahdis.a.,“scararobotcontrol usingneuralnetworks,”icias,vol.1, pp.126 130, 2012. [7] firasa. t.andahmeda. a.,“implementationof fpga basedpsopidcontroller for feedbackivaxscararobot manipulator”, ijcset vol.3,no.10,pp.367–372,2013. [8] jian f.and wei l.,“fourdegreesof freedomscararobot kinematics modeling and simulation analysis scara robot kinematics” ,ij3c,vol.2,no.4, 2013. [9] sudhar.,raghavv.s.,arkoc.,andand padmat., “development of scaramanipulatorwithtwo degrees offreedom usingdc motor,”,arpn journal,vol.8,no.6,pp.445 448, 2013. [10] yousifa.m.,“design,analysis,simulation,an dvirtual realityverifiedintelligentcontroller forindustrialapplication scararobot,” ,international journalof advanc computing ,vol.46,no.3, pp. 1316 2013. [11] zelunl.,zhichengh.,andyoujunh.,“designof spot weldingrobot,” , indonesian journalvol. 11, no. 11, pp. 6267 6273,2013. [12] panchanandj.and biswal b.b.,“aneural network approach for inverse kinematicof a scara manipulator,”ijra, vol.3, no.1, pp. 52–61, 2014. [13] m.shariatee, a.akbarzadeh, a.mousavi,ands.alimardani, “designof aneconomicalscararobotfor industrial applications,”pp. 534–539,2014. position , p.p. 4050 (2017) dmathukumalli v., ol” ,book 2�� , viliam f.,františek ď.,andróbertü.,“analysis of robotic system motioninsimmechanicsandmatlab gui alavudeen a., venkateshwaran n., “computer integrated manufacturing ”, 2010. b., “programmable logic controls”, edition, newnes 2006. pouyaj.andkouroshh.s.,“robotmanipulators: modeling, simulationandoptimalmultiariable control,”appl. mech. mater., mohammada. a. andmahdis.a.,“scararobotcontrol usingneuralnetworks,”icias,vol.1, pp.126– firasa. t.andahmeda. a.,“implementationof fpga basedpsopidcontroller for t manipulator”, 372,2013. jian f.and wei l.,“fourdegreesof freedomscararobot kinematics modeling and simulation analysis scara robot kinematics” ,ij3c,vol.2,no.4, 2013. sudhar.,raghavv.s.,arkoc.,andand padmat., “development of scaramanipulatorwithtwo degrees offreedom usingdc motor,”,arpn journal,vol.8,no.6,pp.445– yousifa.m.,“design,analysis,simulation,an dvirtual realityverifiedintelligentcontroller forindustrialapplication scararobot,” ,international journalof advanced computing ,vol.46,no.3, pp. 1316–1325, zelunl.,zhichengh.,andyoujunh.,“designof spot weldingrobot,” ,telkomnika vol. 11, no. 11, pp. 6267– hanandj.and biswal b.b.,“aneural network approach for inverse kinematicof a scara manipulator,”ijra, vol.3, no.1, pp. m.shariatee, a.akbarzadeh, a.mousavi,ands.alimardani, “designof aneconomicalscararobotfor industrial 9,2014. pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com iman salih karem al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 4050 (2017) 49 [14] niteshk.j.andvijayk.,“3-dof scara type robotmanipulator usingmamdanibasedfuzzycontroller”,ijsre tvol.3,no.3, pp. 659–663, 2014. [15] subhashini p. v. s. ,, rajun.v.s. and rao g. v.“modeling,simulationandanalysisof a scararobot,”arpn j.eng. appl.sci., vol.9, no.4, pp. 398–404, 2014. [16] pouya j.and kourosh h.s.,“robot manipulators:modeling, simulation and optimal multi-variable control,”appl. mech. mater., vol.232, pp.383–387, 2012. [17] https://www.robots.com/faq/show/what-arethe-maintypes-of-robots. [18] [18] kharagpur, “programming of plcs: sequcutial function charts”, version 2 ee iit. [19] ted thayer, “speaking in tongues: understanding the iec 61131-3 programming languages”,bosch rexroth electric drives and controls 2009, plant engineering provides. pdf created with pdffactory trial version www.pdffactory.com https://www.robots.com/faq/show/what-are http://www.pdffactory.com http://www.pdffactory.com )2017( 40-50 صفحة ،2العدد ،13المجلد الھندسیة الخوارزمي جلةم ایمان صالح كریم 50 لمبرمجتصمیم وتنفیذ روبوت نوع سكارا ثالثي درجات الحریة معتمدا مسیطر المنطق ا ***مودة جالء یحي ** طالل عبد الجبار عبد الوھاب *ایمان صالح كریم الجامعة التكنولوجیة /قسم الھندسة الكھرومیكانیكیة *** ،**،* dr_esk_71@yahoo .com : البرید االلكتروني* electromechanical19@yahoo.com : االلكتروني البرید *** الخالصة ،حركتین دورانیھ افقیة يالحریة ذ ثالثي درجات scaraیقدم البحث الحالي عملیة التصمیم والتنفیذ المیكانیكي والكھربائي لروبوت صناعي نوع .وحركة انتقالیة عمودیة واحدة یستخدم الغراض اللحام التحدي .لمكونات المیكانیكیة والكھربائیةالى اختیار ا ال عنفض) plc (ان عملیة التصمیم تضمنت تصمیم مسیطر یعتمد على مسیطر المنطق المبرمج -zelio type sr3)الروبوت المذكور معتمت بالكامل باستخدام مسیطرالمنطق المبرمج نوع .ھو استخدام المكونات الموجوده في العراق وبالكلفھ المعقولة b261bd) نفذ باستخدام لغة ،١٠ومخرجات ١٦مع مدخالتfbd حیث ،یكیا بكفاءة عالیة وبدون اي خطأثالث حركات مختلفة اوتوماتالیجاد اد على برنامج التوصیالتان للذراع تقف في نقطة محددة بعدھا التوصیلة الثالثة تدفع الى االسفل لعمل المھمة ضمن المسار الحركي المرغوب بھ باالعتم ).plc(المسیطر pdf created with pdffactory trial version www.pdffactory.com mailto:electromechanical19@yahoo.com http://www.pdffactory.com http://www.pdffactory.com <4d6963726f736f667420576f7264202d20c7cde3cf20e6dae1ed20d1edc7d620d4c8edc83133372d20313436> al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 14, no.2, june, (2018) p.p. 137146 theoretical prediction of optimum chilled water distribution configuration in air conditioning terminal unit ahmed abd mohammed saleh* ali reyadh shabeeb** department of mechanical engineering/ university of technology/ baghdad*،** @yahoo.com60aamsaleh :email* **email: alishabeeb.reyadh@gmail.com (received 2 july 2017; accepted 18 december 2017) https://doi.org/10.22153/kej.2018.12.006 abstract the distribution of chilled water flow rate in terminal unit is a major factor used to evaluate the performance of central air conditioning unit. in this work, a theoretical chilled water distribution in the terminal units has been studied to predict the optimum heat performance of terminal unit. the central air-conditioning unit model consists of cooling/ heating coil (three units), chilled water source (chiller), three-way and two-way valve with bypass, piping network, and pump. the term of optimization in terminal unit ingredient has two categories, the first is the uniform of the water flow rate representing in statically permanents standard deviation (minimum value) and the second category is the maximum heat transfer rate from all terminal units. the hydraulic and energy equations governing the performance of unit solved with the aid of fortran code with considering the following parameters: total water flow rate, chilled water supply temperature, and variable valve opening. it was found that the optimum solution of three-way valve case at 8°c water supply temperature, 0.12 kg/s total water flow rate and valve opening order (valve 1: 100%, valve 2: 100% and valve 3: 75%) with total heat rate (987.92 watt) and standard deviation (1.181e-3). also, for the two-way valve case the results showed that the optimum condition at 8°c water supply temperature, 0.12 kg/s total water flow rate and valve opening order (valve 1: 75%, valve 2: 75% and valve 3: 50%) with total heat rate and standard deviation (717watt) and (5.69e-4) respectively. .heat rate ,standard deviation ,terminal unit ,way valve-2 ,way valve-3 ,optimization: keywords 1. introduction cooling is essential for all types of buildings in iraq; most of the aircentral conditioning (a/c) systems used in commercial and institutional buildings are of large capacity. these systems use chillers for cooling production and a network of chilled water piping for cooling distribution to the individual air-handling units (ahus) or fan coil units (fcus). the more cooling capacity of cooling system will be accomplished per liter of chilled water distribution if the chilled-water temperature differentials were 8.3°c or greater [1] and if the chilled water temperature difference between supply and return water to the building’s side becomes smaller than the designed value. the energy for heat distribution system and the total energy consumption in district heating and cooling system plant increases in considerable degrees [2] but the high chilled water temperature, low supply air temperature, and high outside air intake ratio may results in low cooling chilled water return temperature and the bypass bridge is not necessary and can be removed in the consumer chilled water system with the 2-way valve configuration. the removal not only reduces first cost but also operation cost [3]. the chilled water distribution system stability is the basic engineering knowledge for air conditioning engineer; proper sizing of control valves, layouts, and self-balancing, flow balancing and control the speed of the pump is an important fundamental factor of chilled water ahmed abd mohammed saleh al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 137146 (2018) 138 distribution system [4]. jing jing liu.et.al (2012)[5] simulated the cooling coil δt profiles with different geometric configurations and various water side and air side conditions using an effectiveness-ntu model and found that the existing water side correlations generated significantly different δt profiles, with variant geometric configurations, the coil δt at full load may be higher, equal, or lower than that at part load, the complexity of cooling coil δt characteristics indicates that it is hard to make conclusions about the coil δt change with cooling loads. jin-ping liu.et.al (2012)[6] built a hydraulic calculation model of pipe network topology, bypass loop hydraulic calculation model and found that when chilled water system is operating in bypass circuit hydraulic adjustable area, pressure difference bypass valve opening and pump operating frequency show an approximately linear relation, which is under little affection of pipe network flow ratio. the aim of this work is to determine theoretically the optimum water flow rate distribution in terminal unit to achieve maximum heat transfer between the water and air sides corresponding to the main parameter effect (flow rate, inlet temperature, and valve opening). 2. governing equations in order to investigate the water distribution network in hvac system, the flow distribution network, pressure drop, heat transfer rate as well as optimization equations were solved using iteration method numerical technique (terminal units), the smallest hvac system that could be found practically content three circuits model , figure (1a & 1b) shows the schematic diagram of this system. (a) the system with 3-way valve (b) the system with 2-way valve. fig. 1. a and b: schematic diagram of the system. ahmed abd mohammed saleh al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 137146 (2018) 139 a) hydraulic model to calculate the head losses in the pipe: h� = h������ + h��� �� ... (1) the frictional head loss h������ is given by darcy-weisbach equation, such as: ℎ ������ = � ℓ � �� �� … (2) where friction factor for laminar flow is: � = �� �� … (3) and for turbulent flow friction factor is defined by zigrang-sylvester formula.: � = −4.0 log�( )ƹ/� ,. − ..(� �� log�(( ƹ/� ,.+ �, ��)2 … (4) where the relative pipe roughness is ƹ � , … (5) (ƹ) is the nickered roughness factor and (d) is tube diameter. table (1) illustrates the internal roughness of many types of pipes. [7] table 1, pipe internal roughness the minor head loss h��� �� is given as; ℎ ��34�� = 56 �� �� … (6) where 56 is (local) loss coefficient, although 56 is dimensionless, it is not correlated in the literature with the reynolds number and roughness ratio but rather simply with the raw size of the pipe. fittings such as elbows, tees, valves, and reducers represent a significant component of the pressure loss in most pipe systems, the calculation of pressure losses through pipe fittings and some minor equipment using the k-value method, the resistance coefficient value (k) are given in table (2).[8] table 2, resistance coefficient (k) the pressure drop can be calculated by : ∆p = 9 : h� … (7) the pressure drop through a 3-way & 2-way valve ∆;<�=>? = )@=�a bcd 2� ∗ 1296000 … (8) table (3) illustrates the flow coefficient (5<f) of valves with different opening [9]. table 3, flow coefficient (ghi) valve opening (in) (mm) flow coeffici ent valve opening percent of total travel 10 20 30 40 50 60 70 80 90 100 3/4 20 kvs 2.4 4.375 6.625 9.075 11.675 14.25 16.825 18.925 20.525 21.55 b) heat transfer model in this study, the (ε-ntu) method has been used for cross-flow heat exchanger with both fluids unmixed. ntu depends on both the heat exchanger design (ua) and the operating conditions (j�34). with the dimensionless number of transfer units (ntu) that is used for heat exchanger analysis and was defined as: klm = n∗o pqrs … (9) where: u = � �tu … (10) rwx = rw�w�y = r + rz�yy + r� … (11) where: material ƹ (centimeters) cast iron 0.026 galvanized iron 0.015 asphalted cast iron 0.012 commercial steel or wrought iron 0.046 pvc 0.00015 fitting nominal pipe size 1/2˝ 3/4˝ 1˝ k value globe valve (full open) 9.2 8.5 7.8 gate valve (full open) 0.22 0.2 0.18 tee straight through 0.54 0.5 0.46 tee through branch 1.62 1.5 1.38 elbow 90˚ 0.81 0.75 0.69 ahmed abd mohammed saleh al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 137146 (2018) 140 rwx: overall heat resistant r ∶ inner resistance rz�yy ∶ wall resistance r� ∶ outer resistance the overall heat resistant rwx consists of three parts: convection heat resistant of the chilled water, conduction heat resistant of the metal wall and convection heat resistant of the air. the overall heat resistance of chilled-water coil was then written as: [10] \]^ = � ^r or + =4(�_/�r) �`ab= + � ^_ o_ … (12) where: ℎ3 = c>∗bb �3 … (13) ℎ� = c>∗bd �u … (14) effectiveness ε, is defined as the ratio of the actual heat transfer rate for a heat exchanger to the maximum possible heat transfer rate. ε = f fghi 0 ≤ ɛ ≤ 1 … (15) j = 1 − lmn o?pqrst.uv w �� cxnpt.�� p y … (16) where: j: capacity ratio = pqrs pqd� … (17) maximum possible heat rate: � = j�34 (l̂ ,3 − l�,3) … (18) the nusselt number for air side is calculated as. [10] k� = 0.117*\l(.�.*;�(.,, … (19) and for chilled water side it is calculated by: for laminar: k� = 1.86 ��? � �r ℓ �(.,,, … (20) for turbulent: k� = 0.023*\l(.�*;�(.� … (21) where ;� = p�∗� b … (22) c) flow variation and standard deviation the following equation evaluates the standard deviation: �� = �� c ∑ (���� − c3�� ���� )² … (23) where, (�����,�����.…flow�) are the values of the flow calculated and � ���� � is the average value of these flow, while the denominator n stands for the size of the sample(in the present work = 3). 3. solution code using fortran code with iteration method technique to solve the governing equations from equation (1) to equation (23) according to the flow chart see figure (2). fig. 2. flow chart of the water distribution network. 4. optimization method the ultimate goal of the optimization was to maximize the value of the total heat rate (summation of three coils) and minimize the variation of flow in the three circuits representing by the standard deviation (sd). to do that we suggested two factors (��) & (��) and the target of optimization is to find the maximum value of (�� ∗ ��) where: �� = 1 − � �¡ �¢ � … (24) ahmed abd mohammed saleh al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 137146 (2018) 141 �� = 1 − �£�¤ �� � … (25) ¥n¦§¨§©ª¦§�« �ª¬¦�� = �� ∗ �� … (26) 5. results and discussion 5.1 total heat rate figure (3) shows that the total heat rate of terminal units at different total water flow rates (0.06, 0.08, 0.1 and 0.12 kg/s) and various water supply temperatures were (8, 10, 12, 14 and 16 °c) at 100% valves opening: (valve 1=100%, valve 2=100% and valve 3=100%), note that the higher total heat rate occurred at minimum water supply temperature (8°c) and at maximum total water flow rate (0.12 kg/s), due to the highest difference in temperature between the water and the air when the temperature of the air is constant, while the increase of the heat rate is slight because the flow type in most cases is laminar and the value of heat transfer coefficient (ℎ3) is almost constant. the same behavior was found in figure (4) and (5), however changing the valve opening from (100-75%) or to 50% for coil no.3 only gave less water flow rate inside this coil, while the total heat rate remained approximately constant. the figures (6) to (9) explain the changes in other 3-way valve opening of coil. these figures indicate that the total water flow rate and water supply temperature has a significant impact on the total heat rate at any valve opening for any coil. figure (10) illustrates the effect of valve opening on the overall heat rate at water supply temperature (8°c) and different total water flow rates (0.06, 0.08, 0.1 and 0.12 kg/s). it can be depict that the lower total heat rate occurred at case (valve 1=100%, valve 2=100%, and valve 3=50%), because coil no.3 is always has the higher water flow rate in comparison with other coils in the cycle, which makes a significant effect on the total heat rate. but figure (11) to (13) shows that the total heat rate of terminal units with the same input parameter in 3-way valve when utilize the 2-way valve. note in all figures that the higher total heat rate occurred at minimum water supply temperature (8°c) and maximum total water flow rate (0.12 kg/s). figure (14) illustrates the effect of valve opening on the overall heat rate at water supply temperature (8°c) and multiple total water flow rates. it noted that the lower overall heat rate occurred at case (valve 1=100%, valve 2=100%, and valve 3=50%) for the same reason in 3-way valve. fig. 3. the total heat rate of terminal units at 8, 10, 12, 14 and 16 °c water supply temperature and valve opening: valve 1=100%, valve 2=100% and valve 3=100%. fig. 4. the total heat rate of terminal units at 8, 10, 12, 14 and 16 °c water supply temperature and valve opening: valve 1=100%, valve 2=100% and valve 3=75%. fig. 5. the total heat rate of terminal units at 8, 10, 12, 14 and 16 °c water supply temperature and valve opening: valve 1=100%, valve 2=100% and valve 3=50%. ahmed abd mohammed saleh al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 137146 (2018) 142 fig. 6. the total heat rate of terminal units at 8, 10, 12, 14 and 16 °c water supply temperature and valve opening: valve 1=100%, valve 2=75 % and valve 3=100. fig. 7. the total heat rate of terminal units at 8, 10, 12, 14 and 16 °c water supply temperature and valve opening: valve 1=100%, valve 2=50 % and valve 3=100%. fig. 8. the total heat rate of terminal units at 8, 10, 12, 14 and 16 °c water supply temperature and valve opening: valve 1=75%, valve 2=100 % and valve 3=100%. fig. 9. the total heat rate of terminal units at 8, 10, 12, 14 and 16 °c water supply temperature and valve opening: valve 1=50%, valve 2=100 % and valve 3=100%. fig. 10. the total heat rate of terminal units at 8°c water supply temperature and valve opening: valve 1=100%, valve 2=100 % and valve 3=100-75-50%. fig. 11. the total heat rate of terminal units at 8, 10, 12, 14 and 16 °c water supply temperature and valve opening: valve 1=100%, valve 2=100% and valve 3=100%. ahmed abd mohammed saleh al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 137146 (2018) 143 fig. 12. the total heat rate of terminal units at 8, 10, 12, 14 and 16 °c water supply temperature and valve opening: valve 1=100%, valve 2=100% and valve 3=75%. fig. 13. the total heat rate of terminal units at 8, 10, 12, 14 and 16 °c water supply temperature and valve opening: valve 1=100%, valve 2=100% and valve 3=50%. fig. 14. the total heat rate of terminal units at 8°c water supply temperature and valve opening: valve 1=100%, valve 2=100 % and valve 3=100-75-50%. 5.2 standard deviation figure (15) illustrates the effect of the total water flow rate on the flow variation representing in standard deviation between the terminal units at (8°c) inlet water supply and constant valve opening of coil no.1, coil no.2 and variable valve opening of coil no.3 (100, 75, 50%) it can be seen that the best standard deviation (minimum) occurred at case (100% 100% 75%). that is mean the amount of flow variation between coils is very low, because coil no.3 has the highest flow rate of the others, therefore decreasing the valve opening of coil no.3 to 75%, which decreases the water flow rate inside the coil and gives closer deviation with the other valves. however decreasing the valve opening of coil no.3 more to 50%. the flow rate in coil no.3 will be very low in comparison with the others, which leads to a great increase in standard deviation. also this figure proves that the standard deviation increases with the increase the total water flow rate, but the water supply temperature does not affect the standard deviation. also in 2-way valve figure (16) illustrates the effect of the total water flow rate on the flow standard deviation between the terminal units at (8°c) inlet water supply and constant valve opening of coil no.1, coil no.2 and variable valve opening of coil no.3 (100, 75, 50%) . it can be seen like in 3-way valve that the best standard deviation (minimum) at case (100% 100% 75%). the reduction in valve opening reduces the standard deviation of flow because the decrease of valve opening means reducing the flow in the coil system, i.e. reducing the variation between the coils (reduce standard deviation) of flow. fig. 15. the flow standard deviation between terminal units at 8 °c water supply temperature and valve opening: valve 1=100%, valve 2=100% and valve 3=100-75-50%. ahmed abd mohammed saleh al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 137146 (2018) 144 fig. 16. the flow standard deviation between terminal units at 8 °c water supply temperature and valve opening: valve 1=100%, valve 2=100% and valve 3=100-75-50%. 5.2 predict the optimum case the optimum conditions are found to give the maximum total heat rate and minimum standard deviation of predetermined values, the optimum values of these circumstances at valve opening (valve 1: 100%, valve 2: 100% and valve 3: 75%), the total water flow rate 0.12 kg/s (7.2 l/min) and the water supply temperature 8°c with a maximum total heat rate of (987.92 watt) and minimum standard deviation (0.001181), the optimization factor could be found by using equations (16), (17) and (18). from figure (17) it can be seen that the maximum optimum factor (0.919894) occurred at 8°c water supply temperature and (0.12 kg/s) total water flow rate. this case is the optimum solution of three-way valve cases. the same procedure can be used to find the optimum condition in two-way valve in a/c system configuration, the optimum values of these conditions at valve opening (valve 1: 75%, valve 2: 75% and valve 3: 50%), the total water flow rate 0.12 kg/s (7.2 l/min) and the water supply temperature 8°c with a maximum total heat rate of (717 watt) and minimum standard deviation (0.000569), figure (18) shows that the optimization factor at each flow rate and each water supply temperature. fig. 17. optimization factor of three-way valve case. fig. 18. optimization factor of two-way valve case. 6. conclusions 1. the total heat rate in a/c terminal unit is minimum at the lowest valve opening, highest water supply temperature and lowest total water flow rate, whereas the total heat rate is maximum at the maximum valve opening, highest total water flow rate and lowest water supply temperature. 2. the last valve (no.3 in current model) highly effect on the distribution of flow rate at each terminal unit. therefore, the optimum value of maximum total heat rate and minimum standard deviation occurred when valve order (valve 1= 100%, valve 2=100% and valve3=75%) in three way valve case. also, in a 2-way valve the optimum value of maximum total heat rate and minimum standard deviation occurred when valve opening (valve 1= 75%, valve 2=75%, and valve 3=50%). ahmed abd mohammed saleh al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 137146 (2018) 145 3. the supply temperature has the greater impact on the total heat rate than valve opening and total water flow rate. 4. the valve opening and total water flow rate has the significant influence on the standard deviation, while the water supply temperature does not effect on it in 3-way and 2-way valve. 5. the diameter of the bypass pipe in 2-way valve system should be much lower than the diameters of the system. nomenclature aircentral conditioning a/c standard deviation sd friction factor ƒ length of the pipe with constant diameter in (m). ℓ internal diameter of the pipe in (m) d average velocity of flow in (m/s) v gravity constant g kinematic viscosity of the fluid (m²/s) ­ pressure drop in (n/m²) ∆p heat transfer coefficient of water side (w/m².k) ℎ3 minimum capacity rate (w/ k) j�34 maximum capacity rate (w/ k) j��® maximum possible heat transfer rate (w) ���® inlet temperature of air (k) l̂ 3 inlet temperature of water (k) l�3 specific heat (j/kg.k) cp dynamic viscosity (n.s/m²) ¯ thermal conductivity (w/m.k) k overall heat transfer coefficient (w/m².k) u relative pipe roughness ƹ heat transfer coefficient of air side (w/m².k) ℎ� temperature difference δt total heat rate factor f1 standard deviation factor f2 maximum value of total heat rate m actual value of total heat rate q the range between maximum and minimum value of total heat rate \� actual value of standard deviation s minimum value of standard deviation z the range between maximum and minimum value of standard deviation \� optimum factor f 7. references [1] donald p. fiorino,"achieving high chilledwater delta ts", ashrae journal vol.41, (1999). [2] shimoda yoshiyuki, minoru mizuno, shigeki kametani and shin-ichi kawamura, "evaluation of distribution system performance in district heating and cooling system." proceedings of sixth international ibpsa conference, (1999). [3] gang wang, mingsheng, bin zheng, and mingsheng liu. , "impacts on building return water temperature in district cooling systems", asme 2006 international solar energy conference, american society of mechanical engineers, (2006). [4] thirakomen kecha and ashrae thailand chapter–bog, "stabilizing chilled water distribution" ashraei thailand chapter journal, pp. 27-31, (2007). [5] jingjing liu, hui li and zhiqin zhang, "simulations of chilled water cooling coil delta-t characteristics ", ashrae transactions 118, (2012). [6] jin-ping liu, xue-feng liu, ji-dong lu, lei liu and wei zou, "research on operating characteristics of direct-return chilled water system controlled by variable temperature difference", energy vol. 40. 1, pp. 236–249, (2012). [7] benefield, larry d., joseph f. judkins, and a. david parr, "treatment plant hydraulics for environmental engineers", englewood cliffs, new jersey: prentice-hall, (1984). [8] friction losses in pipe fittings resistance coefficient k, http://www.metropumps.com/resourcesfrictionlos sdata.pdf. [9] fisher controls international, inc., catalog 12, u.s.a., (2001). [10] holman j. p., "heat transfer", tenth edition, by the mcgraw-hill companies, inc., (2010). )2018( 137-146، صفحة 2د، العد14دجلة الخوارزمي الهندسية المجلم احمد عبد محمد صالح 146 المركزيةتوزيع االمثل للماء المثلج في الوحدات الطرفية في منظومة التكييف النظري لل تخمينال ** علي رياض شبيب *احمد عبد محمد صالح الجامعة التكنولوجية/ بغداد قسم الهندسة الميكانيكية/ yahoo.com60aamsaleh@البريد االلكتروني: * alishabeeb.reyadh@gmail.com البريد االلكتروني:** الخالصة م أداء وحدة تكييف الهواء المركزية. في هذا العمل، تم اجراء دراسة ويتوزيع معدل تدفق المياه المثلجة في الوحدات الطرفية عامال رئيسا يستخدم لتق ديع أداء حراري للوحدة الطرفية. يتكون نموذج وحدة تكييف الهواء المركزية من الملف التبريد / بأفضلفي الوحدات الطرفية للتنبؤ مثلجةنظرية لتوزيع المياه ال صطلح خة. إن مالتدفئة (ثالث وحدات)، مصدر المياه المثلجة (المبرد)، صمام ثالثي االتجاه وصمام ثنائي االتجاه مع مجرى جانبي، وشبكة األنابيب، ومض أعظموالفئة الثانية هي التحسين في الوحدة الطرفية يشمل جزئين األول هو معدل تدفق المياه المنتظم الذي يتمثل في االنحراف المعياري الثابت (القيمة الدنيا) تم حلها بمساعدة برنامج فورتران مع االخذ معدل نقل للحرارة من جميع الوحدات الطرفية. المعادالت الهيدروليكية ومعادالت الطاقة التي تحكم أداء الوحدة جد أن الحل األمثل بنظر االعتبار العوامل المتغيرة االتية: إجمالي معدل تدفق المياه، ودرجة حرارة إمدادات المياه المثلجة، وفتحات صمام متغيرة. وقد و : ١/ ثانية إجمالي معدل تدفق المياه وعند فتحة صمام (صمام كجم ٠٫١٢ووية، درجة مئ ٨لحالة الصمام الثالثي االتجاه عند درجة حرارة امداد بالمياه تبلغ ). أيضا بالنسبة لحالة الصمام ثنائي 1.181e-3واط) وانحراف معياري ( ٩٨٧٫٩٢٪) مع معدل حرارة كلي ( ٧٥: ٣٪ وصمام ١٠٠: ٢٪، صمام ١٠٠ م / ثانية مجموع معدل تدفق المياه وعند فتحة صمام غك ٠٫١٢و حرارة إمدادات المياه،درجة مئوية درجة ٨االتجاه أظهرت النتائج أن الحالة المثلى عند التوالي.) على 5.69e-4(واط)، ٧١٧() مع معدل حرارة كلي وانحراف معياري %٥٠: ٣٪ وصمام ٧٥: ٢٪، صمام ٧٥: ١(صمام al-khwarizmi engineering journal al-khwarizmi engineering journal,vol. 12, no. 2, p.p. 2733 (2016) large eddy simulation in duct flow jalal m. jalil* ihab omar abbas** *,** department of machine and equipment engineering / university of technology * e-mail: jalalmjalil@yahoo.com ** e-mail: ihabomar88 @yahoo.com (received 26 april 2015; accepted 22 march 2015) abstract in this paper, the problem of developing turbulent flow in rectangular duct is investigated by obtaining numerical results of the velocity profiles in duct by using large eddy simulation model in two dimensions with different reynolds numbers, filter equations and mesh sizes. reynolds numbers range from (11,000) to (110,000) for velocities (1 m/sec) to (50 m/sec) with (56×56), (76×76) and (96×96) mesh sizes with different filter equations. the numerical results of the large eddy simulation model are compared with k-ε model and analytic velocity distribution and validated with experimental data of other researcher. the large eddy simulation model has a good agreement with experimental data for high reynolds number with the first, second and third mesh sizes and the agreement increase near the wall of the duct. the percentage error for the large eddy simulation model with experimental data of the (56×56) mesh size is less than 18 % and for the (76×76) mesh size is also less than 17% and for the (96×96) mesh size is less than 16 %. the large eddy simulation model show high stability and do not need extra differential equation like the k-ε model and a great saving in time and computer memory was achieved. keywords: large-eddy simulation, turbulence model, computational fluid-dynamics. 1. introduction the turbulent flow is a flow regime described by chaotic and stochastic property changes; this involves low momentum diffusion, high momentum convection, and rapid variation of pressure and velocity in space and time. until now no expected theory has been established which might be used with success to the vast variety of turbulent flows confronted in practice and consequently the treatment of most of these flows is counted on theoretical and numerical approximations. some of these models are k-ε, large eddy simulation (les), reynolds averaged navies-stokes (rans) and direct numerical simulation (dns). g. mompean [1] performed a numerical simulation with the non-linear turbulence model coupled with the k-ε equations .the fully developed turbulent flow through a straight square duct, incuding secondary motion, was simulated. l. c. demartini, et al., [2] presented the numerical and experimental analysis of the turbulent flow of air inside a channel of rectangular section, involving two rectangular baffle plates. m. taeibi-rahni, et al., [3] applied an eddy-viscosity sub grid-scale model in largeeddy simulation at re=4700 of a film cooling flow. the model requires only a single-level test filter, and therefore was more appropriate for large-eddy simulation (les) in complicated geometries. t. s. lund [4] used explicit filtering in large eddy simulation (les) with finitedifference methods. the idea that the finite difference expressions act as an effective filter was shown to be false for three-dimensional simulations performed on nonuniform meshes. michele ciofalo,[5] discussed large-eddy simulation (les) results for the turbulent flow with heat transfer in different geometrical configurations, involving a plane channel, a channel bearing transverse square ribs on one of the walls, and a crossed-corrugated air heater. mingde su, et al., [6] used the smagorinsky sub grid-scale model, a dynamic sub grid-scale model, and a stimulated sub grid-scale model to compute airflow in a room in a large eddy simulation (les) mailto:jalalmjalil@yahoo.com jalal m. jalil al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 2733(2016) 28 program. the present work is to investigate the problem of turbulent developing flow in rectangular duct by using large eddy simulation model in two dimensions with different reynolds number, filter equations and mesh sizes and compare the results with the k-ε model and analytic velocity distribution and experimental data of other researcher. 2. theoretical concept during the last two decades there has been great interest in developing computational fluid dynamics (cfd) computer programs for predicting the air flow. the majority of these cfd programs are counted on the solution of navier– stokes equations, the energy equation, the mass and concentration equations as well as the transport equations for turbulent velocity and its scale [7]. 2.1. prandtl mixing length the mixing length (l) is introduced as the average lateral distance through which a small mass of fluid particles would move from one layer to the other adjacent layers before getting the velocity of the new layer. prandtl assumed that components u′and υ′are of the same order and the velocity fluctuation in x-direction is related to the mixing length [8]. τ = ρu′ × υ′ … (1) u′ = l du dy … (2) u′ × υ′ = u′ υ′ = l du dy l du dy = l 2 du dy 2 … (3 ) υ′ = l du dy … (4) substituting the value of u′ υ′ in eqn. (1), we get τ = ρl 2 du dy 2 … (5) by neglect viscous shear stress u um = y ro n … (6) 2.2. basic governing equations the conservation equations for continuity, momentum, and energy equations and turbulence model can be written as follows [9]: conservation of mass (continuity equation) the change in mass flow within a control volume should be equal to the mass flow in minus the mass flow out through the control volume surfaces, since mass cannot be created or destroyed. this can be expressed mathematically for an incompressible fluid as: ∂u ∂x + ∂v ∂y = 0 … (7) navier-stokes equations (momentum equation): the momentum equations that govern the flow of fluid are concluded from the second law of motion by newton (the conservation of momentum). the equations are called navierstokes equations, two dimensions, non-uniform and incompressible fluid takes the form: ρ ∂ uu ∂x + ∂ vu ∂y = − ∂p ∂x + 2 ∂ ∂x γ ∂u ∂x + ∂ ∂y γ ∂u ∂y + ∂ ∂y γ ∂v ∂x … (8) ρ ∂ uv ∂x + ∂ vv ∂y = − ∂p ∂y + ∂ ∂x γ ∂v ∂x + 2 ∂ ∂y γ ∂v ∂y + ∂ ∂x γ ∂u ∂y … (9) 2.3. the k-ε turbulence model the kε turbulence model is counted on the solution of equations for the turbulent kinetic energy and the turbulent dissipation rate. the distribution of eddy viscosity throughout the flow domain should be organized in order to compute the momentum and heat diffusion coefficients for turbulent equations. this is the function of the turbulence model. the turbulence models implicitly establish the related strength of turbulent and molecular diffusion by computing the μ t distribution, the turbulence models implicitly establish the relative strength of turbulent and molecular diffusion [10]. the eddy viscosity is related to magnitudes of turbulence kinetic energy (k) and the dissipation rate of turbulence energy (ε) at each grid point: μt = cd ρ k2 ε … (10) where cd is the empirical constant. the turbulent energy is known by the fluctuation velocities k = 1 2 (u′2 + v′2) jalal m. jalil al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 2733(2016) 29 the local distribution of k and ε demand the solution of two additional transport equations, which are divided from the navier-stokes equation. the k transport equation is presented by: ∂ ∂x ρuk + ∂ ∂y ρvk = ∂ ∂x γk ∂k ∂x + ∂ ∂y γk ∂k ∂y + gk − ρε … (11) gk = μt 2 ∂u ∂x 2 + ∂v ∂y 2 + ∂u ∂y + ∂v ∂x 2 … (12) the ε equation is given by: ∂ ∂x ρuε + ∂ ∂y ρvε = ∂ ∂x γϵ ∂ε ∂x + ∂ ∂y γϵ ∂ε ∂y + c1gk − c2ρε ε k … (13) 2.4. large eddy simulation model large-eddy simulation (les), is a modelling technique that calculates for turbulent flows where the large, energy-carrying turbulent eddies are computed directly and the effect of the small-scale eddies below the computational grid size, which donate to the turbulence energy dissipation, are modeled through a sub grid-scale stress term. the large turbulent scales in les are often distinguished from the small scales by using a spatial filtering process, which determines to what degree the large-scale eddy motions in a turbulent flow are explicitly resolved [7]. 2.5. smagorinsky model the smagorinsky model is counted on the equilibrium hypothesis which implies that the small scales dissipate entirely and instantaneously all the energy they undergo from the large scales. les calculations of concern are executed with equal mesh spacing in two spatial directions δx and δy. the sub grid scale eddy viscosity, in this model, is related to the deformation of the resolved velocity field as: μt = cs∆ 2 s … (14) where s = 2sij sij 1 2 s = is the magnitude of the strain-rate tenser. s ij = 1 2 ∂u i ∂xj + ∂u j ∂xi … (15) δ = width filter δ=(δx δy)1/2 cs = smagorinsky coefficient the smagorinsky coefficientcs , in the present paper, is set equal to 0.17. this sub grid model largely employed in les of isotropic turbulence presented good results. when it applied to homogeneous, and in particular to wall bounded flows, the constant was modified. for two dimensions the magnitude of the strain-rate tenser will be: s = (2sxx sxx + 4sxy sxy + 2syy syy )1/2 … (16) where sxx = 1 2 ∂u ∂x + ∂v ∂x … (17) sxy = 1 2 ∂u ∂y + ∂v ∂x … (18) syx = 1 2 ∂v ∂x + ∂u ∂y = sxy … (19) syy = 1 2 ∂v ∂y + ∂u ∂y … (20) 2.6. spatial filtering filtering is a mathematical operation designed to move out a range of small scales from the solution to the navier-stokes equations in the context of large eddy simulation (les). turbulent flows comes from the wide range of length and time scales because the principal difficulty in modeling, this operation produces turbulent flow modeling cheaper by decreasing the range of scales that should be resolved. the les filter operation is low-pass, meaning it separates out the scales accompanied with high frequencies. the filter that used in the program is box filter and the equation of box filtering for two dimensions for fig. (1) as below [11]: fig. 1. grid points for two dimensions. jalal m. jalil al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 2733(2016) 30 fi,j = fi,j + fi+1,j + fi+2,j + fi−1,j + fi−2,j + fi,j+1 + fi,j+2 + fi,j−1 + fi,j−2 /9 . . . (21) others equation of box filtering are: fi,j = fi+1,j + fi+2,j + fi−1,j + fi−2,j + fi,j+1 + fi,j+2 + fi,j−1 + fi,j−2 /8 … (22) fi,j = 2fi+1,j + fi+2,j + 2fi−1,j + fi−2,j + 2fi,j+1 + fi,j+2 + 2fi,j−1 + fi,j−2 /12 . . . (23) fi,j = 3fi+1,j + fi+2,j + 3fi−1,j + fi−2,j + 3fi,j+1 + fi,j+2 + 3fi,j−1 + fi,j−2 /16 … (24) fi,j = 4fi,j + fi+1,j + fi+2,j + fi−1,j + fi−2,j + fi,j+1 + fi,j+2 + fi,j−1 + fi,j−2 /12 … (25) fi,j = 12fi,j + 4fi+1,j + fi+2,j + 4fi−1,j + fi−2,j + 4fi,j+1 + fi,j+2 + 4fi,j−1 + fi,j−2 /32 … (26) 3. mesh generation the generation of computational mesh that is used for the discretized solution of two dimensional navier-stokes and continuity equations is three sizes of mesh as followed: 56×56 76×76 96×96 the partial differential equations fully describe duct air flow. however, the equations are nonlinear and coupled. numerical discretization techniques are presented to transform the problem to a solvable level. in essence, this includes approximating the governing differential equations by a system of algebraic relations. this is accomplished by subdividing the duct into finite volumes using a gridding system with the finite volume method. these located at the centers of the finite volumes rather than solving over the continuum pressures and velocities are expected only at discrete points. fortran version (4.00.5277) was used to solve the governing equations for flows through a two-dimensional duct based on finite volume method by an iterative method. the fig. (2) blow shows the subroutine of les. fig. 2. subroutine of les. 4. boundary and initial condition of the duct the geometry considered is a duct model. the duct model has length up to 10 m and 0.127×0.127 m2cross section area. fig. (3) shows basic dimensions of the duct geometry model. the boundary conditions used for the straight square rectangular duct is the velocity at the wall equal zero. the initial condition used for the straight square rectangular duct is different initial inlet velocities (2 to 11 m/sec) and the exit velocity is smooth exit. fig. 3. test duct dimensions. 5. results and discussion in this paper, the results are presented to compare the velocity distribution for different numerical models inside rectangular duct of cross section area (0.127×0.127m2) and length of the duct up to (10 m). results have been obtained for different reynolds numbers, mesh sizes, and filter equations. the current numerical results are compared with the kε turbulence model and prandtl mixing length numerical results, experimental results and the process that has been obtained from previous research for the purpose of validation. u &v input data calculate uf,vf,uuf,vvf&uvf from filter equation calculate du dx , du dy , dv dx & dv dy by finite difference method calculate μ t = cs∆ 2 s s ij= 1 2 ∂u i ∂xj + ∂u j ∂xi calculate s = 2sij sij 1 2 0.127 m 10 m jalal m. jalil al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 2733(2016) 31 5.1. filter equations velocity distribution was studied at reynolds number (22300) with different filter equations (21 to 26). the results obtained for velocity (3.3833 m/sec) at reynolds number 22 300 for filter equations from (21) to (26) as shown in fig. (4).the result does not change for each filter equation. the velocity profiles are similar to each other and there are no apparent effects of filter equation on these profiles that mean the average velocity for each control volume is equal. the change of the velocity profile for each velocity and reynolds number carried out. the fig.(4) show the distribution of mean velocity between the half high of the square duct and the maximum velocity for different values of reynolds number, where the reynolds number is based on the inlet velocity and hydraulic diameter of the square duct. the profiles are strongly asymmetric and are appreciably dependent on reynolds number. 0 1 2 3 4 5 u (m/sec) 0 0.02 0.04 0.06 0.08 y (m ) les eq.(20) les eq.(21) les eq.(22) les eq.(23) les eq.(24) les eq.(25) fig. 4. velocity distribution for different filter eqs.at re=22300. 5.2. mesh sizes the velocity distribution was studied filter equation (21) with different mesh sizes (56×56), (76×76) and (96×96) at reynolds number (34,300). these values were taken to compare the numerical results with the experimental data of ref [12] for validation. in fig (5), the comparison shows an acceptable agreement between the present work and published data for the (56×56), (76×76) and (96×96) mesh sizes. the difference between the experimental and numerical results at the (56×56) mesh size was less than 18% and for the (76×76) mesh size was less than 17% and for (96×96) mesh size was less than 16%. 0 2 4 6 8 u (m/sec) 0 0.02 0.04 0.06 0.08 y (m ) les mesh (56x56) les mesh (76x76) les mesh (96x96) exp ref [12] fig. 5. velocity distribution for different mesh sizes at re=34300. fig. (6) shows a comparison of velocity distribution obtained from eddy simulation, k-ε, analytical models respectively.the calculations were carried out at re=34000 and mesh size (96×96). the large eddy simulation model has a good agreement with the experimental data ref [12] near the wall. the k-ε model and analytic velocity distribution are very close. the large eddy simulation model shows high stability for calculation than the k-ε model where there is no source of error came from the negative value under the square root that obtained .the large eddy simulation model does not need extra differential equation to solve with the momentum equation like k and ε equations. 0 2 4 6 8 u (m/sec) 0 0.02 0.04 0.06 0.08 y ( m ) les ke ana exp ref [12] fig. 6.velocity distribution at re=34,300 of (𝟗𝟔 × 𝟗𝟔) mesh size. jalal m. jalil al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 2733(2016) 32 6. conclusions from the results of the present work, the following conclusions are deduced: 1. the filter equation does not change the numerical results for all cases at different reynolds numbers. 2. the agreement of the velocity distribution between the large eddy simulation model and the experiment data of ref [12] increase with increase of reynolds number. 3. the agreement of the velocity distribution between the large eddy simulation model and the experiment data of ref [12] increase with increase of the mesh generation. 4. large eddy simulation model has a good agreement with the experimental data ref [12] near the wall. nomenclature u',v' fluctuations, lateral and vertical velocity components respectively 𝑚/𝑠 l mixing length 𝑚 um maximum velocity 𝑚/𝑠 u instantaneous velocity 𝑚/𝑠 ro radius of pipe 𝑚 y depth of flow 𝑚 cd empirical constant / k turbulent kinetic energy 𝑚2/𝑠2 gk generation rate of turbulence energy / cd smagorinsky coefficient / δ width filter 𝑚 ε turbulent energy dissipation rate 𝑚2/𝑠2 γ. diffusion coefficient -- ρ density 𝑘𝑔/𝑚3 μt eddy viscosity 𝑝𝑎.𝑚 τ shear stress 𝑝𝑎 subscripts t turbulent m maximum o outlet 7. references [1] g. mompean,"numerical simulation of a turbulent flow near a right-angled corner using the speziale non-linear model with rng k-ε equations", computers & fluids, vol. 27, pp. 847-859, (1998). 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[6] mingde su, qingyan chen, che-ming chiang,"comparison of different sub gridscale models of large eddy simulation for indoor airflow modeling", journal of fluids engineering, volume 123, pp. 628-639, (2001). [7] hazim b. awbi," ventilation of buildings", spon press, 2th edition, (2005). [8] r.k. rajput, "a text book of fluid mechanics and hydraulics machines", s.chand & company ltd., (2008). [9] sinan mazin hazim ,"the effect of phase change material section on the convection heat transfer coefficient", m.sc. thesis, technical college/baghdad (2011). [10] nassir ibraheem khalaf, “experimental and numerical analysis of air outlet configuration in air-conditioned space”, m.sc. thesis, technical college/baghdad (2008). [11] klaus a.hoffmann," computational fluid dynamics for engineerings ", 4th edition, engineering education system, (1989). [12] lawrence c. hoagland "fully developed turbulent flow in straight rectangular ducts -secondary flow, its cause and effect on the primary flow", phd thesis, mechanical engineering , massachusetts institute of technology, (1960). (2016) 2733، صفحت 2، انعذد12دجهت انخىارزمي انهنذسيت انمجموجالل محمذ جهيم 33 محاكاة انذوامت انكبيرة نجريان داخم مجري **ايهاب عمر عباس* جالل محمذ جهيم اندبيؼـخ انزكُىنىخُـخ / قسى هُذسخ انًكبئٍ وانًؼذاد ** ،* jalalmjalil@yahoo.com: انجشَذ االكزشوٍَ* ihabomar88 @yahoo.com:انجشَذ االكزشوٍَ** انخالصت ثبسزخذاو انسشػخ نزىصَغ َظشَخ َزبئح خالل يٍ انًقطغ يشثغ يدشي خالل ػذدَخ َظشَخ دساسخ انًضطشة اندشَبٌ رطىس دساسخ رىهزا انجسث فٍ و( m/sec 50) انً( m/sec 1) يٍ رزشاوذ وسشع( 110,000) انً( 11,000)يٍ رزشاوذ َىنذصٌس السقبو االثؼبد ثُبئُخ انكجُشح انذوايخ يسبكبح سَخَظ يغ يقبسَزهب رى انكجُشح انذوايخ يسبكبح نًُىرج سَخانُظ انُزبئح(.96×96) و( 76×76) و( 56×56) انشجكبد يثم يخزهفخ شجكبد و يخزهفخ رصفُخ يؼبدالد سبثق نجبزث انًخزجشَخ انُزبئح يغ انكجُشح انذوايخ يسبكبح نًُىرج سَخانُظ انُزبئح يقبسَخ اَضب رى. انزسهُهٍ ورجووانٍ نالضطشاة( k-ε) اخشٍَ ًَىرخٍُ انؼبنُخ َىنذصٌس السقبو انًخزجشَخ وانُزبئح نالضطشاة ًَىرج و انكجُشح انذوايخ يسبكبح انؼذدَزٍُ سَزٍُانُظ ثٍُ خُذ رقبسة وخىد انً رشُش انُزبئح وكبَذ انذوايخ يسبكبح نًُىرج% 18 يٍ اقم كبَذ نهخطأ انًئىَخ َسجخال اٌ ػهًب.اندذاس يٍ ثبنقشة انزقبسة وَضداد وانثبنثخ وانثبَُخ االونً انشجكخ ثبسزخذاو َسجُب انشجكخ ثبسزخذاو انخطب َسجخ كبَذ زٍُ فٍ. اَضب% 17 يٍ اقم( 76×76) ونهشجكخ( 56×56) كخانشت ثبسزخذاو انجبزث نُفس انًخزجشَخ انُزبئح يغ انكجُشح سَخَظ فٍ كًب نهسم اضبفُخ رفبضهُخ ويؼبدالد كثُشح يزغُشاد رسزبج وال ػبنُخ اسزقشاَخ رىضر انكجُشح انذوايخ يسبكبح سَخَظ% . 16 يٍ اقم( 96×96) (k-ε )نهسبسىةو سؼخ انزاكشح انىقذ رىفش كًب . mailto:jalalmjalil@yahoo.com 117129 haider mohammed mekkiyah al al-khwarizmi engineering journal,vol. 12, no. 1, p.p. improving shear strength of soft clay by using torn belts chips haider department of civil eng (received abstract random throwing of industrial waste has a significant impact on the environment unless it takes into account the conditions of engineered destroying and/or re projects represents a well-planned project in order to resolve a lot of engineering problems for some difficult soils. the objective of this study was to evaluate the capability and effects of rubber shreds (rs) from scrap torn belts towards improving the shear strength of soft clay parameters were investigated to study the influence of rs content, water content, normal stress, and dilation ratio. from experimental test results it was found that previous para content was found effective in improving the shear strength of soft clay when the normal stress increases provided that fixed water content used in the mixture. cohesion, c and angle of fricti (1.5-2) respectively. however, it was revealed that rs content mustn’t exceed the liquid limit level of soft soil. if the water content increases and exceeding the liquid limit level of soft clay, shear stren will begin to decrease by reduction percentage of (15% inclusion. the dilation ratio was highly affected by water content increment; disturbed path of dilation rati observed with increasing water content in soil keywords: improvement, very soft clay, rubber shreds, direct shear, shear strength 1. introduction soft soil can be found everywhere especially throughout the coastal area. this soil deposit generally consists of unconsolidated soil strata predominantly clays, silts or mixtures of both. the main concern about soft clay is the low shear strength which typically varies with loading, drainage conditions and amount of settlement. geotechnical works in deep deposit of highly compressible soft clay are often associated with problems such as excessive differential settlement, negative skin friction and bearing capacity failure. in short, improving footing stability, increasing bearing capacity, cost reduction, preserving the environment and reducing settlements are the primary purposes of reinforcing such soil mass. for example, the horizontal stress induced in retaining wall structural system would be only one-half lower than conventional backfill, which leading to a less expensive retaining structure al-khwarizmi engineering journal, vol. 12, no. 1 khwarizmi engineering journal,vol. 12, no. 1, p.p. 117129 (2016) improving shear strength of soft clay by using torn belts chips haider mohammed mekkiyah civil engineering/ college of engineering/ university of baghdad email: hydmekk@yahoo.com (received 14 april 2015; accepted 15 september 2015) random throwing of industrial waste has a significant impact on the environment unless it takes into account the conditions of engineered destroying and/or re-used. taking the advantage of re-using waste materials in engineering planned project in order to resolve a lot of engineering problems for some difficult soils. the objective of this study was to evaluate the capability and effects of rubber shreds (rs) from scrap torn belts towards improving the shear strength of soft clay. a direct shear tests were conducted on soft clay-rs mixture. the following parameters were investigated to study the influence of rs content, water content, normal stress, and dilation ratio. from experimental test results it was found that previous parameters affecting the shear strength of soft clay. increasing rs content was found effective in improving the shear strength of soft clay when the normal stress increases provided that fixed water content used in the mixture. cohesion, c and angle of friction, φ were increased by ratio of 2) respectively. however, it was revealed that rs content mustn’t exceed the liquid limit level of soft soil. if the water content increases and exceeding the liquid limit level of soft clay, shear strength, cohesion and angle of friction will begin to decrease by reduction percentage of (15%-55%) and (20%-45%) respectively in spite of 30% rubber inclusion. the dilation ratio was highly affected by water content increment; disturbed path of dilation rati observed with increasing water content in soil mixture. provement, very soft clay, rubber shreds, direct shear, shear strength. soft soil can be found everywhere especially throughout the coastal area. this soil deposit generally consists of unconsolidated soil strata predominantly clays, silts or mixtures of both. the main concern about soft clay is the low shear pically varies with loading, drainage conditions and amount of settlement. geotechnical works in deep deposit of highly compressible soft clay are often associated with problems such as excessive differential settlement, capacity failure. in short, improving footing stability, increasing bearing capacity, cost reduction, preserving the environment and reducing settlements are the primary purposes of reinforcing such soil mass. for example, the horizontal stress induced in retaining wall structural system would be only half lower than conventional backfill, which leading to a less expensive retaining structure design and these materials can be assigned as new method for improving the shear strength of soft soil [1]. [2] investigated full scale retaining wall of 4.88 m height constructed with horizontal earth pressures of 35.9 kpa, surcharges and varying magnitudes of outward wall rotation were measured. the horizontal stress at rotation about the base of 0.01 h was about the tire shreds. moreover, the horizontal stress at this rotation using shreds was about 35% less than active stress expected for conventional granular backfill. [3] conducted a laboratory study for preliminary assessment of the mechanical behavior of shredded tire backfills. a triaxial testing program was conducted to investigate the stress-strain relationship and strength of tire chips sand mixture. the numerical modeling results suggest tire shreds, particularly when mixed with sand, may be effectively used as backfill. , no. 1, p.p. 117129 (2016) al-khwarizmi engineering journal (2016) improving shear strength of soft clay by using torn belts chips university of baghdad random throwing of industrial waste has a significant impact on the environment unless it takes into account the using waste materials in engineering planned project in order to resolve a lot of engineering problems for some difficult soils. the objective of this study was to evaluate the capability and effects of rubber shreds (rs) from scrap torn belts towards rs mixture. the following parameters were investigated to study the influence of rs content, water content, normal stress, and dilation ratio. from meters affecting the shear strength of soft clay. increasing rs content was found effective in improving the shear strength of soft clay when the normal stress increases provided that were increased by ratio of (1.4-2.3) and 2) respectively. however, it was revealed that rs content mustn’t exceed the liquid limit level of soft soil. if the gth, cohesion and angle of friction %) respectively in spite of 30% rubber inclusion. the dilation ratio was highly affected by water content increment; disturbed path of dilation ratio were design and these materials can be assigned as new method for improving the shear strength of soft estigated full scale retaining wall of 4.88 m height constructed with horizontal earth pressures of 35.9 kpa, surcharges and varying magnitudes of outward wall rotation were measured. the horizontal stress at rotation about the base of 0.01 h was about the same for used tire shreds. moreover, the horizontal stress at this rotation using shreds was about 35% less than active stress expected for conventional granular ted a laboratory study for preliminary assessment of the mechanical ehavior of shredded tire backfills. a triaxial testing program was conducted to investigate the strain relationship and strength of tire chipssand mixture. the numerical modeling results suggest tire shreds, particularly when mixed with e effectively used as backfill. haider mohammed mekkiyah al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 117129 (2016) 118 mixtures of sand and tire chips present un intermediate response between those of pure sand and pure tire chips. rubber-sand mixture has an initial tendency to contract, followed by dilation. this is a typical response of sand, but the range of strains for which there is contraction is wider than sands, and dilatancy is much less. [4] mentioned that in geotechnical related works, lightweight materials are mostly taken as filling materials for road construction purposes. this will reduce or minimize the foundation requirements, reduce land cutting for mountainous area, prevent settlement and shorten construction times. in case of retaining wall, lighter fill will reduce the lateral earth pressure thus reducing the structural requirements of the wall including the foundation. [5] studied the effect of adding small particles of waste tire rubber on swelling potential of an expansive soil from colorado. the index properties and compaction parameters of the rubber, expansive soil, and rubber-soil mixture tested were determined. one dimensional swell consolidation tests were performed and found out that rubber-soil mixtures are more compressible than untreated soil; both the swell percent and the swelling pressure are significantly reduced by the addition of rubber to the expansive soil. [6] studied the use of rubber strips with length less than 25 mm and diameter less than 3.6 mm. mixture compositions is 10% by dry-weight of tire buffing with low plasticity kaolin clay, tested using triaxial test. their findings showed that the strength in both drained and undrained condition is higher than that of clay alone. however, this is provided that a certain limiting level of confinement of 200-300 kpa is applied, above this threshold the presence of inclusions tends to degrade the strength of the clay. [7] investigated the reinforcement of sandy soil polymer fiber material, the test results on model square footings showed that bearing capacity and subgrade reaction were increased due to fiber materials. vertical settlement analysis were achieved for both experimental and predicted settlement, the results showed that the difference in analysis and experimental results are still in accepted limits in the view of footing settlement design criteria. the lateral and vertical restraint in the values of initial settlement at small loads can be avoided from the random fiber distribution in the sandy soil below the footing. the fiber materials also prevent the failure lines in soil below the footing to propagate in flow direction of failure towards the tensile arc strain locations. finally, the soil behavior in terms of bearing capacity, settlement reduction and restraining the initial vertical settlement of footing during early stage of loading is improved. comparison between experimental and predicted (calculated) settlement below the footings showed that the difference in ranges were within accepted limits for foundation settlements design. from the literature studied it was found that the particle size, shape, the mix proportion of rs and soft clay properties are considered as strong parameters that may influence the shear strength of soft soil-rs mixture. 2. rubber particle size size of rubber shred particles plays an important role in defining the soft soil strength. if the particle size is too large, it is difficult to be tested by conventional soil laboratory equipment. statistical and theoretical analysis of reported properties suggests that the engineering properties of rubber particles on small scale specimens are generally representative of larger shred size particles [8]. figure (1) shows small shredded belt particles that were used in testing program of this study. 3. rubber particle shape shape of particle can be of many types such as angular, plate, circular, etc. however, particle shape may affect the strength of rubber-soft clay mixture if the appropriate shape is not been identified. this has been proven by results tested by past researchers. angular rubber particles [9] and [10] were found to decrease the unconfined compression strength of clay. with above concerned problem, the research has been done to investigate the feasibility of using torn belt chips to reinforce soft clayey soil. direct shear tests were conducted on mixtures of soft clay and rubber shreds particles from scrap torn belts with different water content. in iraq, soft clayey soil can be found especially throughout the coastal area in the south part of iraq (i.e. fao city). 4. material used in summary the research has been conducted to investigate the properties of soft clay when mixed with shredded rubber from scrap torn belts towards improving the shear strength of soft clay based on the testing program shown in table (1). torn belts (rs) (i.e. rubber shreds from scrap torn haider mohammed mekkiyah al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 117129 (2016) 119 belts) contains two basic materials; rubber, and fiber. in order to improve the properties of soft clay, shredded belt chips are being used and mixed with compressible weak clayey soil. their unit weight being about one-third of the soft soil, the rubber-soil mixture would apply a smaller overburden stress resulting in a lower settlement and an increased global stability of soft clayey soil. in order to prepare soft soil-rs mixture, firstly, amount of soft clay is mixed thoroughly with half desired percentage of water to obtain uniformity then mixed with the percentage of rs to obtain a uniform mixture (i.e. percentage of rs used was by dry weight of the soft clay). the remaining water percentages is sprayed onto the surface of the soft soil-rs mixture and then mixed thoroughly and stored in plastic bags for (12-18) hrs to achieve the stable mixture condition. finally, the soil mixture filled in shear box by tamping method to prevent any voids that can be developed between tamped layers followed by procedure of [11], such tamping method is to enhance the preparation of soft clay samples in shear box due its natural consistency (i.e. tamping method achieved for both bottom and top soil layers). for ease of reference, the abbreviations for ‘rs’ and ‘wc’ will be denoting as rubber shreds and water content respectively. the total series of test that will be carried out with three normal loading for each test, 5 kg (49.033 n), 10 kg (98.066 n) and 15 kg (147.099 n) of 21 tests is summarized in table (1). table 1, testing program. no. types of test moisture content, wc (%) no. of tests 1 soft clay + 0% rs 40 3 2 soft clay + 10% rs 40 3 3 soft clay + 30% rs 40 3 60 3 80 3 100 3 4 soft clay + 50%rs 40 3 5. soft clay the soil used in this study is classified as lean clay (cl) based on the unified soil classification system, the physical geotechnical properties are listed in table (2). table (2), physical geotechnical properties of soft clay property units value natural water content, w % 46-48 plastic limit, pl % 26 ∗liquid limit, ll % 46 plasticity index, pi % 20 specific gravity, gs 2.55 natural moist unit weight, γt kn/m3 16.2-17.5 natural dry unit weight, γd kn/m3 11.1-11.8 initial void ratio, eo 1.12-1.25 maximum dry unit weight, γd /e kn/m3 14.8/0.69 optimum water content, w % 15.4 compression index, cc 0.25-0.27 activity, a 0.85 unified classification cl ∗natural water content in soil is ≥ than ll. 6. shredded belt in engineering industry sector, belts, tires, and other rubber materials poses serious environmental problem. majority of these wastes end up in landfill waste. the torn waste belt (i.e. used in equipment cooling units) was proposed in the testing program with the dimension in average are (1.5 to 2.0 mm) in width, (2 to 2.5 mm) in thickness and (9.5 to 9.8 mm) in length as shown in figure (1). fig. 1. raw shredded belt. 7. direct shear test direct shear test (drained test) is a method for investigating the shear strength of soil beside other methods such as unconfined test and triaxial compression test. it differs somewhat from the other two in that they are “compression” tests (i.e. shear failure is affected by a compression force), whereas in direct shear test the shear failure caused by a shear force along a predetermined haider mohammed mekkiyah al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 117129 (2016) 120 horizontal surface. the direct shear test can be performed on both cohesion and cohesionless soils, and it can evaluate both cohesion, c and angle of friction, φ. these parameters are used to evaluate a soil’s shear strength. a 100 mm x 100 mm shear box was used in this study and the selected running shearing machine speed was at rate of 0.006 mm/sec. the normal loads used on the samples were 5 kg (49.033 n), 10 kg (98.066 n) and 15 kg (147.099 n). fig. 2. direct shear test. 8. test results and discussions the behavior of soft clay-rs mixture was investigated in order to evaluate the influence of rs content on shear strength of soft soil under three normal loadings; 5 kg (49.033 n), 10 kg (98.066 n) and 15 kg (147.099 n). the following main parameters were discussed from obtained testing results; effects of different rs content with fixed moisture content and effects of different moisture content with fixed rs content on the shear strength of mixtures. 9. effect of rubber shreds with fixed water content on the behavior of soil mixture 9.1. shear stress versus horizontal strain from figure (3) shown the shear stress at failure for soft clay-rs mixture increases as the normal loading increased. the shear stress versus εh relationships showed strain hardening behaviors up to failure till the soil reaches the ultimate or critical states criteria where they continue to distort at a constant rate. dilation process happens when the shearing machine keeps encountering soft and hard particles which make the shearing stress low and high at different stage of loadings. shear stress of mixture vs. rs content and/or normal stress is shown in figure (4) indicating that maximum shear stress increases with increasing the percentage of rs content and the value of maximum shear stress at failure increases as the normal stress increased as well. a summary of maximum shear stress for 5 kg (49.033 n), 10 kg (98.066 n) and 15 kg (147.099 n) loading for each test is tabulated in table (3) table 3, maximum shear stress obtained at 40% wc. tested sample maximum shear stress (kpa) cohesion, c (kpa) angle of friction, φφφφ ∗∗∗∗∗∗∗∗ratio of improvement in angle of friction normal load (kg) 5 10 15 ∗40 % wc+ soft clay + 0% rs 5.2 6.8 8.3 3.6 17.62° 40 % wc+ soft clay +10% rs 7.5 10.1 12.2 5.0 26.4° 1.50 40 % wc+ soft clay + 30% rs 10.7 14.3 16.2 7.8 30.5° 1.73 40 % wc+ soft clay + 50% rs 12.4 16.1 19.0 8.4 37.12° 2.15 ∗ water content in soil mixture is < than ll. ∗∗ rate of improvement in friction angle were highly pronounced from test results than cohesion values. applied load, n principle stress ratio at failure top shear halve rubber fiber lower shear halve head contact haider mohammed mekkiyah al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 117129 (2016) 121 fig. 3. shear stress vs. horizontal strain at 40% wc. fig. 4. (a) maximum shear stress vs. rs content, (b) max. shear stress at failure vs. normal stress. (∗∗∗∗the values of friction angle (ф) and cohesion (c) are obtained by drawing a common tangent to effectivestress mohr’s circles (mohr-coulomb envelope) for various tests). 0 5 10 15 20 0 10 20 30 40 50 60 m a x . s h e a r s tr e ss , ττ ττ (k p a ) rs (%) 5 kg 10 kg 15 kg (a) 0 5 10 15 20 25 0 5 10 15 20 m a x . s h e a r st re ss , ττ ττ( k p a ) ∗∗∗∗ normal stress, σ (kpa) 0 % rs 10 % rs 30 % rs 50 % rs (b) haider mohammed mekkiyah al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 117129 (2016) 122 9.2. vertical strain versus horizontal strain figure (5) showed the contractive soil behavior during shear stage which is due to simultaneous elastic and plastic strains developed at shear stage for both soft clay and rubber particles. the vertical displacement increases as normal loads increases (minus sign on the value of vertical strain represents the compression). the vertical displacement reduced with increasing the rs content due to restraints of these rubber materials at the failure plane that create zone of complex and higher principal stress ratio at failure (σ′1/σ′3). finally the trend behavior of vertical strains values was found to be affected by rs content as shown in table (4). fig. 5. vertical strain vs. horizontal strain at 40 % wc. table 4 , maximum vertical displacement (strain) observed at 40 % wc. tested sample maximum vertical strain, εεεεv (%) normal load (kg) 5 10 15 40 % wc+ soft clay + 0% rs 0.672 0.733 0.819 40 % wc+ soft clay + 10% rs 0.432 0.585 0.716 40 % wc+ soft clay + 30% rs 30.36 0.515 0.618 40 % wc+ soft clay + 50% rs 0.337 0.424 0.537 9.3. dilation ratio versus shear stress ratio from figure (6) in terms of rate of dilation, the soil exhibits moderate dilation ratio (dr) at the beginning of shear stage then a lower dilation ratio observed at the end of shearing stage. the shear stress ratio at failure is reduced with increasing normal stress. -0.9 -0.7 -0.5 -0.3 -0.1 0 5 10 15 20 v e rt ic a l s tr a in , εε εε v (% ) horizontal strain, εεεεh (%) soft clay only 5 kg 10 kg 15 kg -0.9 -0.7 -0.5 -0.3 -0.1 0 5 10 15 20 v e rt ic a l s tr a in , εε εε v (% ) horizontal strain, εεεεh (%) soft clay +10% rs 5 kg 10 kg 15 kg -0.9 -0.7 -0.5 -0.3 -0.1 0 5 10 15 20 v e rt ic a l s tr a in , εε εε v (% ) horizontal strain, εεεεh (%) 40% wc+soft clay +30% rs 5 kg 10 kg 15 kg -0.9 -0.7 -0.5 -0.3 -0.1 0 5 10 15 20 v e rt ic a l s tr a in , εε εε v (% ) horizontal strain, εεεεh (%) soft clay +50% rs 5 kg 10 kg 15 kg haider mohammed mekkiyah al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 117129 (2016) 123 fig. 6. shear ratio vs. dilation ratio at 40 % wc, improved behavior with increasing rs% 10. effects of different moisture content with fixed rs content on the behavior of soil mixture 10.1. shear stress versus horizontal strain the purpose of this series of experiment is to observe the effect of increasing moisture content along with fixed rs content at 30% on the shear strength of soil mixture. test results of shear strength of soft clay-rs mixture are shown in figure (7) which indicates the maximum shear stress decreases with increasing water content. figure (8) showed the shear strength of soft clayrs mixture reduces as the water content increased. a summary of maximum shear stress values for 5 kg (49.033 n), 10 kg (98.066 n) and 15 kg (147.099 n) loading for each test are tabulated in table (5) and as the water content increases and exceeding the liquid limit level of soft clay, cohesion and angle of friction will begin to decrease. 0 0.5 1 1.5 2 0 0.04 0.08 0.12 0.16 s h e a r r a ti o , ( ττ ττ / σσ σσ )) )) dilation ratio, (dy/dx) soft clay only 5 kg 10 kg 15 kg dr at the end of test dr at the beginning of test 0 0.5 1 1.5 2 0 0.04 0.08 0.12 0.16 s h e a r r a ti o , ( ττ ττ / σσ σσ )) )) dilation ratio, (dy/dx) soft clay +10% rs 5 kg 10 kg 15 kg 0 0.5 1 1.5 2 2.5 3 0 0.1 0.2 0.3 0.4 s h e a r r a ti o , ( ττ ττ / σσ σσ )) )) dilation ratio, (dy/dx) soft clay +30% rs 5 kg 10 kg 15 kg dr at the beginning of test dr at the end of test 0 0.5 1 1.5 2 2.5 3 0 0.1 0.2 0.3 0.4 s h e a r r a ti o , ( ττ ττ / σσ σσ )) )) dilation ratio, (dy/dx) soft clay +50% rs 5 kg 10 kg 15 kg dilation ratio path towards failure haider mohammed mekkiyah al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 117129 (2016) 124 fig. 7. shear stress vs. horizontal strain at 30% rs. fig. 8. (a) maximum shear stress vs. water content; (b) maximum shear stress vs. normal stress at 30% of rs content (∗∗∗∗the values of friction angle (ф) and cohesion (c) are obtained by drawing a common tangent to effective-stress mohr’s circles (mohr-coulomb envelope) for various tests). 0 5 10 15 20 0 5 10 15 20 s h e a r s tr e ss , ττ ττ (k p a ) horizontal strain, εεεεh (%) 40% wc+soft clay +30% rs 5 kg 10 kg 15 kg 0 5 10 15 20 0 5 10 15 20 s h e a r s tr e ss , ττ ττ (k p a ) horizontal strain, εεεεh (%) 60% wc+soft clay +30% rs 5 kg 10 kg 15 kg 0 5 10 15 20 0 5 10 15 20 s h e a r s tr e ss , ττ ττ (k p a ) horizontal strain, εεεεh (%) 80% wc+soft clay +30% rs 5 kg 10 kg 15 kg 0 5 10 15 20 0 5 10 15 20 s h e a r s tr e ss , ττ ττ (k p a ) horizontal strain, εεεεh (%) 100% wc+soft clay +30% rs 5 kg 10 kg 15 kg 0 5 10 15 20 25 20 40 60 80 100 120 m a x . s h e a r s tr e ss , ττ ττ (k p a ) water content, w (%) 5 kg 10 kg 15 kg (a) 0 5 10 15 20 25 0 5 10 15 20 m a x . s h e a r s tr e ss , ττ ττ (k p a ) ∗∗∗∗normal stress, σ (kpa) 40 % w 60 % w 80 % w 100 % w (b) haider mohammed mekkiyah al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 117129 (2016) 125 table 5, maximum shear stress obtained at 30 % rs. tested sample maximum shear stress(kpa) cohesion, c (kpa) angle of friction, φφφφ % of reduction in friction angle normal load (kg) 5 10 15 40%wc+ soft clay +30%rs 10.7 14.1 16.2 7.8 30.5° 60%wc+ soft clay +30%rs 9.1 11.0 12.9 6.6 24.1° 20 80%wc+ soft clay +30%rs 6.2 8.5 10.7 4.6 20.38° 33 100%wc+ soft clay +30%rs 4.8 6.6 8.6 3.5 16.85° 45 table 6, maximum vertical displacement (strain) observed at 30% rs. tested sample maximum vertical strain, εεεεv (%) normal load (kg) 5 10 15 40% wc+ soft clay + 30% rs 0.36 0.515 0.618 60% wc+ soft clay + 30% rs 0.899 1.261 1.371 80% wc+ soft clay + 30% rs 1.058 1.347 1.475 100% wc+ soft clay + 30% rs 1.162 1.453 1.743 10.2. vertical strain versus horizontal strain figure (9) shows the pronounced contraction soil behavior (i.e. highly compressed) and the values of vertical strains increases as the water content increased. table (6) shows the effect of water content on the vertical strain values; test results showed that increasing wc causes increasing the vertical strain regardless of the rs content. -2 -1.8 -1.6 -1.4 -1.2 -1 -0.8 -0.6 -0.4 -0.2 0 0 5 10 15 20 v e rt ic a l s tr a in , εε εε v (% ) horizontal strain, εεεεh (%) 40 % wc +soft clay +30% rs 5 kg 10 kg 15 kg -2 -1.8 -1.6 -1.4 -1.2 -1 -0.8 -0.6 -0.4 -0.2 0 0 5 10 15 20 v e rt ic a l s tr a in , εε εε v (% ) horizontal strain, εεεεh (%) 60% wc+soft clay +30% rs 5 kg 10 kg 15 kg haider mohammed mekkiyah al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 117129 (2016) 126 fig. 9. vertical strain vs. horizontal strain at 30% rs 10.3. dilation ratio versus shear stress ratio from figure (10) the shear ratio decreased as wc increased along when exceeding liquid limit of soft clay. the dilation ratio path was highly disturbed from the beginning of the test up to the failure stage (inverted s-shape) especially at higher water content in soil mixture. fig. 10. shear ratio vs. dilation ratio at 30% rs, disturbed behavior with increasing wc. -2 -1.8 -1.6 -1.4 -1.2 -1 -0.8 -0.6 -0.4 -0.2 0 0 5 10 15 20 v e rt ic a l s tr a in , εε εε v (% ) horizontal strain, εεεεh (%) 80% wc+soft clay +30% rs 5 kg 10 kg 15 kg -2 -1.8 -1.6 -1.4 -1.2 -1 -0.8 -0.6 -0.4 -0.2 0 0 5 10 15 20 v e rt ic a l s tr a in , εε εε v (% ) horizontal strain, εεεεh (%) 100% wc+soft clay +30% rs 5 kg 10 kg 15 kg 0 0.5 1 1.5 2 2.5 0 0.1 0.2 0.3 0.4 s h e a r r a ti o , ( ττ ττ / σσ σσ )) )) dilation ratio, (dy/dx) 40% wc + soft clay +30% rs 5 kg 10 kg 15 kg dr at the beginning of test dr at the end of test 0 0.5 1 1.5 2 2.5 0 0.1 0.2 0.3 0.4 s h e a r r a ti o , (/ σσ σσ )) )) dilation ratio, (dy/dx) 60% wc+soft clay +30% rs 5 kg 10 kg 15 kg 0 0.5 1 1.5 2 0 0.1 0.2 s h e a r r a ti o , ( ττ ττ / σσ σσ )) )) dilation ratio, (dy/dx) 80% wc+ soft clay +30% rs 5 kg 10 kg 15 kgdisturbed dilation ratio path due to water content (inverted s-shape) 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 0 0.05 0.1 0.15 0.2 s h e a r ra ti o , ττ ττ/ σσ σσ dilation ratio, (dy/dx) 100 wc+soft clay +30% rs 5 kg 10 kg 15 kg disturbed dilation ratio path due to haider mohammed mekkiyah al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 117129 (2016) 127 11. conclusions from series of tests carried out on soft clay-rs mixture using direct shear test; the following conclusions are drawn from this study: • effect of rubber shreds with fixed water content on the behavior of soil mixture in general the failure criteria for soft clay-rs mixture based on maximum shear stress, vertical settlement, and dilation ratio values at failure are defined as follows; gradual increase in shear stress as the shear strain increases until an approximately constant shear stress critical state is attained. contraction or compressive volumetric strains (i.e. for the soil mixture) become stiffer mixture as the shear strain increases until reaching the critical state of soil mixture. increasing rs content was found effective in improving the shear strength of soft clay with increasing the normal stress. cohesion, c and angle of friction, φ were increased as well. the vertical displacement reduced with increasing the rs content which is due to restraints of these rubber materials at the failure planes that create zone of complex and higher principal stress ratio at failure (σ′1/σ′3). the shear strength of soft clay-rs mixture increased by ratio of (1.40 to 2.3) for 10% rs to 50% rs respectively with fixed water content of 40%. the settlement (i.e. vertical strain) reduced by (13% to 50%) for 10% rs to 50% rs respectively. the shear strength increment and/or settlement reduction are compared with (40% wc and 0% rs content). the soil exhibits moderate dilation ratio (dr) at the beginning of shear stage then a lower dilation ratio observed at the end of shearing stage and gradually reduces the shear stress ratio at failure with increasing normal stress. it may be due to soil consistency as soft mixture state and fabric assembly of rubber particles in the prepared samples, sliding would be initiated on the horizontal plane, once the motion occurred, the soil would tend to move into the void spaces of rubber particles developing a downward directional component as vertical strain, indicating contraction behavior of soil mixture. • effect of water content with fixed rubber shreds on the behavior of soil mixture the behavior of soft clay at 30 % rs content mixture mixed with different water content (40% wc to 100% wc) as follows. the reason after selection of higher water content greater than liquid limit of soil in this study; is to investigate the behavior of soil mixture in case of water content is increased in soil ground improved with such technique. the shear strength reduces as the water content increased even when the rubber shreds is available in soil mass for different normal stress values. cohesion, c and angle of friction, φ were reduced with increasing water content. the shear strength of soft clay-rs mixture is reduced by ratio of (15% to 55%) for 60% wc to 100% wc respectively. the settlement increased by (2.2 to 3.2) for 60% wc to 100% wc respectively. the shear stress at failure was decreased as wc increased. the dilation ratio path was highly disturbed from the beginning of the test up to the failure stage (inverted s-shape was observed) especially at higher water content in soil mixture. the shear strength reduction and/or settlement increment are compared with (40% wc and 30% rs content). such behavior cause finally increasing the settlement and /or contractive soil behavior of soil mixture. 12. references [1] humphrey d.n. (1996)," tire chips: a new road-building geomaterial", transportation research board (trb), washington, d.c.vol.184, and no.17. [2] tweedie j. j., humphrey d. n. and sandford t. c. (1998), “tire shreds as lightweight retaining wall backfill: active conditions”, journal of geotechnical and geoenvironment engineering, asce, vol. 124, no. 11, pp.(1061-1070). [3] lee j. h., salgado r., bernal a. and lovell c. w. (1999), “shredded tires and rubbersand as lightweight backfill”, journal of geotechnical and geoenvironment engineering, asce, vol. 125, no. 2, pp(132141). [4] ghani a. n. (2002) “shredded scrap tire based lightweight geomaterial for civil engineering works” master thesis, school of civil engineering, usm. [5] seda j. h., joon c., lee. a. j., and carraro j. a. h. (2007). “beneficial use of waste tire rubber for swelling potential mitigation in expansive soil” asce, geotechnical special publication 157/174, pp.(1-9). [6] ozkul z. h. and baykal g. (2007), “shear behavior of compacted fiber-clay composite in drained and undrained loading”, journal of geotechnical and geoenvironment engineering, asce, vol. 133, no. 7, pp.(767-781). haider mohammed mekkiyah al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 117129 (2016) 128 [7] mekkiyah, h. m. (2013). “improvement of soil behavior by using polymer fiber materials underneath square footing", journal of engineering, college of engineering, baghdad university, isn 17264073, july, no.7, volume 19, pp.(873-882). [8] strenk, p. m., wartman, j., grubb, d. g., humphrey, d. n., and natale, m. f. (2007). “variability and scale dependency of tire derived aggregate”, journal of material in civil eng., vol. 19(3), pp.(233-241). [9] black b. a., and shakoor a. (1994). “a geotechnical investigation of soil-tire mixture for engineering application”, proceeding of the first international conference on environmental geotechnical, bitech publication, pp.(617-623). [10] al-tabbaa a., and aravinthan t. (1998). “natural clay-shredded tire mixture as landfill barrier material”, waste management journal, issue 1, vol. 18, pp.(9-16). [11] astm d3080 / d3080m – 11, “standard test method for direct shear test of soils under consolidated drained conditions”. )2016( 117129، 67%� 1، ا*4#د12#()� ا*12ارز"/ ا*.-#, � ا*$()" ' #ر "%$# "! � 129 e" g h%i=و"� ا*c?(* de@� ا*b � ا*4a 6� @=,?2#ام ر8=>; ا:'9"� ا*89$$� ' #ر "%$# "! � 2345# 01&اد/ ا),+&*# .-$# /ا),+&*# ا)'&%$# "! hydmekk@yahoo.com: ا)>8;& ا:.89و6% �7j2*ا أن ا4l3%$# ا:=4دة u3 ھsه ا)+4o;4ت وأ4dدة . ر63 ا)+4o;4ت ا)jbd klb1 #$d4+mاc-d 8$<. 8$fg? h( 6i ا)>$e# 43 ) ?8اcd ا)8bوط ا),+&*$# =6 أ?<=,4 4w$wx? ky'; #$*&+,(ا z;4رb'(ا4,3 =6 ا&x9*ا>lb'(ا u3 8$yl(ا k[( 2># ت5$&اm(ا)89ب ا ]ا),+&*$# ا)69 ?42%6 3+,4 21. jه ا)&را*# ھsھ u3 ا)80ض _?j#o$2`(ا #$+$w(89ب ا-( a_(3_4و3# ا u$![9( #"b''(3# اbc:ا u3 di8اe ام&x9*8 أ$fg?14-$# و" ; . u3 g$-h c-d 8e4<'(ا a_(ا a[= 6+<? ?zw" 2w_'(4ط اw'(ا)49)$#و. وا)189# #ا k3اj2(درا*# ا ? &": i(s.و ،g-!'(دي اj'2(ى ا)'4ء، 3_&ار ا:4,5د اj9[3 ،#$4طw'(ا zw_(ا #<!%)dilation ratio .( a_(3_4و3# ا c-d 8fn? ه>dأ k3اj2(ا)2'-$# أن ا oi49+(ل ا>h u3 qcj( #189-( .ى ز;4دةj9[3rs ز;4دة z3 #$+$w(189# ا-( a_(3_4و3# ا u$![? s<<* s14f 6i43 ىj9[3 ل>h u3دي وj'2(وزوا;. ا:4,5د ا i*4'9(أن ا qcj(4 4كl9c:6 ازداد?4 أ;`4 ا-h4وز %!># ا)&اu? م&d 8طb1rs #189-( #(j$!(ا &c ud #o$2`(ا #$+$w(ى ا). اj9[3 4ل ز;4دةc 6= 8$<. klb1 8fg9? k3اj2(ه اs4ك أن ھl9c:وزوا;# ا i*4'9(ا u3 k. 4نm_% qcj( v$c #(j$!(ا &c ىj9[3 ud 4ء' 6-h( %!>#. ا)&اdilation ratio (4ء'(4دة %!># ا;b1 8ا$y. 8تfg? qcj-= ه 3!4رjb?)dilation ratio (#189(ا g$-h 6= 4دة %!># ا)'4ء;b1. al-khwarizmi engineering journal al-khwarizmi engineering journal,vol. 12, no. 2, p.p. 7989 (2016) numerical simulation of the collector angle effect on the performance of the solar chimney power plant arkan k. al-taaie* waheeds s. mohammad** abbas j. jubear*** *,**department of mechanical engineering/ university of technology ***department of mechanical engineering /university of wassit ***email: abbas kut72@yahoo.com.au (received 5 january 2014; accepted 12 january 2016) abstract sloped solar chimney system is a solar chimney power plant with a sloped collector. practically, the sloped collector can function as a chimney, then the chimney height can be reduced and the construction cost would be reduced.the continuity, naver-stockes, energy and radiation transfer equations have been solved and carried out by fluent software. the governing equations are solved for incompressible, 3-d, steady, turbulent standard k model with boussiuesq approximation to develop for the sloped solar chimney system in this study and evaluate the performance of solar chimney power plant in baghdad city of iraq numerically by fluent (14) software with orking conditions such as solar radiation intensity (300,450,600,750 and 900 w/m2), and collector which angle (0°, 15° and 30°).the results show that the change of collector angle has considerable effects on the performance of the system.the velocity increases when the collector angle increases and reach to the maximize value at a collector angle (30°). the temperature increase with the collector tile angle increase at solar intensity times (7:30,8:15,9,10 am) but decrease at 12:30 pm) corresponding to solar intensities. the study show that iraqi wather are suitable for this system. keywords: solar chimney; solar energy; collector; natural convection. 1. introduction the solar chimney is a power plant that uses, solar radiation to raise the temperature of the air and, the buoyancy of warm air to accelerate the air stream flowing through the system. the main features of the solar chimney are sketched in fig.1. air is heated as a result of the greenhouse effect under a transparent roof (the collector). because the roof is open around its periphery, the buoyancy of the heated air draws a continuous flow from the roof perimeter into the chimney. a turbine is set in the path of the air current to convert the kinetic energy of the flowing air into electricity. fig. 1. schematic layout of the conventional solar chimney power plant. [1] mailto:kut72@yahoo.com.au arkan k. al-taaie al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 7989(2016) 80 in 1981 a solar chimney prototype of 50 kw and chimney height nominally at 200 m was built in manzanares, spain. the plant operated from 1982 to 1989, and was connected to the local power network between 1986 and 1989 [2]. this project menstruated the viability and reliability of the solar chimney concept since then, numerous investigations have been conducted to predict the flow in solar chimneys. generally, it was found that the electricity yielded by a solar chimney is in proportion with the intensity of global solar radiation, collector area and chimney height. based on a mathematical model, schlaich [2] reported that optimal dimensions for a solar chimney do not exist. however, if construction costs are taken into account,thermo economically optimal plant configurations may be established for individual sites. pretorius and kr ِ ger [3] showed numerically that the power generation is a function of the collector roof shape and inlet height. ref. [4] showed analytically that the plant performance depends on the plant size. to overcome the disadvantage of low efficiency, only large-scale plants, in which the chimney heights are 1000 m or more, were proposed in the literature (e.g. [5,6]). as a result, the installation cost of such a plant is very high. cost analysis for commercial-scaled solar chimney power plants can be found in refs. [7-10]. to overcome the high investment cost, researchers have proposed some novel and non-conventional concepts. the concept of constructing a solar collector surrounding a hollow space excavated in a mountain was introduced in ref. [11]. the hollow space can be used as a chimney of the system. it was shown that the cost for constructing a chimney structure can be reduced and the technology would be suitable for mountainous countries. in addition, papageorgiou proposed the concept of a floating solar chimney technology [12].ref. [13] proposed a solar chimney system for power production at high latitudes, where sloped lands are readily available and sunshine is at acceptable levels. the authors suggested building a solar chimney collector system on a sloped surface or suitable hill. a mathematical model and the performance of the solar chimney system with a sloped collector are presented in this paper. this kind of system is hereinafter called the (sloped solar chimney power plant) sscpp. the analytical models for flows in sscpp had been proposed in refs. [13,14,15].while they were useful in their own rights, but the range of application was limited due to the neglect of dynamic pressure [13] and the exclusion of flow details within the collector ([13,14,15]). in the present study, a mathematical model that includes the dynamic pressure and the flow details within the collector is developed. as there is no experimental result of sscpp published,the proposed model is validated by comparing its results with the predictions of the commercial cfd package. comparisons of the present results with those obtained by other models are also performed. 2. numurical implementations advanced solver technology provides fast, accurate cfd results, flexible moving and deforming meshes, and superior parallel scalability. computational fluid dynamics (cfd) procedures solve all the interacting governing equations in a coupled manner, albeit in a finite framework. with a careful use of cfd, its results could be used to validate those of the theoretical models, at least qualitatively. 2.1. modelling in gambit for the simulation part, the model is designed by using gambit 2.4.6 for those four configurations. this software is provided by the advanced geometry and meshing tools. the functions of gambit are design the three dimensional (3-d) model of three configurations, setup the boundary condition for each edge and faces of each configuration and provide the meshing analysis for each configuration. the solar chimney power plant was modeled with the following dimensions: circular absorber ground with a diameter of 6 m , inclined collector angle (θ = 0°,15°and 30°), chimney height 6m,chimney diameter 0.3m and the gap between the absorber and the transparent cover (glass) is 0.1m as shown in fig.2. arkan k. al-taaie al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 7989(2016) 81 fig. 2. physical prototype. the numerical examination of the flow behavior of air under the steady state condition was studied at both the inlet and the chimney base where the turbine is expected to be staged. the fluid flow calculation was simulated using fluent software. the buoyancy driven flow in the system was assumed to be turbulent based on previous studies. set up the boundary condition is to define the situation occur at the surface condition in term of friction. meanwhile, defining the meshing is vital in order to discrete each part to certain section for more accuracy fluent’s analysis. it is important to define, model, meshing, and boundary conditions before running into fluent. proper boundary conditions are needed for a successful computational work. after it has been to create a geometry where we have one volume where is defined the specify boundary types of solar collector, solar chimney and the base such as the wall , while the entry and exit zone type is inlet and outlet-pressure. now the assembly is meshed using tetrahedral elements of t-grid scheme type [16] .gambit scheme with spacing interval size (0.0275) is chosen as shown in fig. 3, the gambit grid generator with approximately 2 million computational cells for different cases. no-slip condition for velocity and temperature on the walls was used. fig. 3. computational grid. 2.2. simulation with fluent fluent solves the governing integral equations for the conservation of mass, momentum, energy, and other scalers, such as turbulence.there are two processors used to solve the flow and heat transfer equations. the first preprocessor is the program structure which creates the geometry and grid by using gambit. the second post processor is solving naverstokes equations continuity, momentum and energy. the set of conservation equations used by cfd are: mass conversiotion equation momentum equation k-ε model equations d d h l θ arkan k. al-taaie al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 7989(2016) 82 the viscous medium is also taken.the analysis is carried out using turbulent flow and then the standard k-epsilon and standard wall functions near wall functions [17]. the discrete ordinates (do) was selected under the solar load model enables radiation heat transfer. define the the sun direction vector, by enter the values for the x, y, and z components. in the current study different direct solar irradiation (300 ,450 ,600 ,750 ,900 w/m 2 ) data were obtained from ministry of transportationiraqi meteorological organization and seismology of baghdad city of 8-8-2008 in the following times (7:30 , 8:15 , 9 ,10 a.m. and 12:30 p.m.) and the sun direction vector is obtained from [18]. boundary conditions specify the flow and thermal variables on the boundaries of the physical model. they are, therefore, a critical component of the fluent simulations and it is important that they are specified appropriately. the boundary conditions applied in this work is shown in table (1) [19]. table 1, boundary conditions in detail. boundary type boundary condition inlet pressure inlet ∆p=0 ; t= tambient; exit pressureout let ∆p=0; t = tambient – 0.0065* chimney height ground (asphalt) wall thermal condition: mixed h=8 w/m2k;t=tambint chimney wall wall constant heat flux: q=0 glass(semitransparent) wall thermal condition: radiation(thicness=0. 004mm 3. simulation results in order to validate the results of the numerical part of the present work, a comparison with the numerical study of [20] was carried out. it can be seen from figs. (4) and (5) that at the same dimensions of solar chimney power plant a good agreement with the numerical results is achieved of absorbing ground temperature and exit velocity when using asphalt aggregates as an absorption background, at radiation intensities of (310,415,505 w/m 2 ). fig. 4. comparison of the variation in absorbing ground temperature with solar insolation , with an numerical study [20]. fig. 5. comparison of the variation in exit air velocity with solar insolation, with an numerical study[20]. 3.1. variation of the solar intensity and sunlight direction the results of the temperature distribution and velocity vectors of solar insolation (300,450,600,750 and 900 w/m 2 ) at times of numerical results [20] present work numerical results [20] present work arkan k. al-taaie al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 7989(2016) 83 (7:15,8:15,9,10 am and 12:30 pm) with d=6m ,h= 6m and collector angle (0 ° , 15°and 30 ° ) regarding the solar chimney passage are presented in figs. (6 to 23). the increase in air velocity is very small up to about half the radius of the collector. the very steep increase is obtained in the inner half of the collector. this trend is noticed in all solar intensities and sunlight direction as shown in figs. (7), (10), (13), (16) ,(19) and (22). the reason is due to the combined effect of flow area reduction and the amount of the heat transfer from the ground to the working fluid, which increases the kinetic energy of the flow particles. generally to compare the velocities of the air at the solar collector passage for different solar intensity times (7:30,8:15,9,10 am and 12:30 pm), it could be seen that the maximum velocity occurs in the (900w/m 2 ) solar radiation intensity at (12:30 pm) and the minimum velocity in the morning with (300w/m 2 ) solar intensity at (7:15am). the numerical solution has shown that the velocity in the center of the chimney is higher than near the wall. the ground temperature also increases near the collector inlet but show a small decrease near the collector outlet. this is attributed to higher heat transfer coefficients present near the collector counter as shown in figs.(6),(9),(12),(15),(18),and(21). the development of flow in the chimney can be seen through the enlargement regions shown in figs. (8), (11), (14), (17) ,(20),and (23). the flow in the chimney is similar to close conduits viscous forces cause a flow velocity profile to form such that the fluid flows slower close to the walls and a change in the flow type cases a change in the velocity profiled.the flow in the lower and middle regions is developing non uniform flow, but in the top region is uniform fully developed flow (turbulent flow). the heat transfer model is used to compare the performance of a conventional solar chimney power plant with three collector orientations at (0 ° , 15°and 30 ° ). results indicate that the larger collector angle leads to improve performance of the solar chimney in the morning and give rise to the strong influence of the sunlight direction of the velocity and temperature fields. 3.2. maximum temperature difference the buoyancy driving force takes effect due to the gravity force, so the larger the collector tilt, the stronger the influence of buoyancy effect will be. fig. (24) presents the temperature difference for collectors of different tilt angles. the temperature difference increases at the tilt angle increase when the solar intensity is (300,450,600, and 750 w/m 2 ) but it decreases at (900w/m 2 ) due to the sunlight direction as it is approximately perpendicular. the slope angle is the angle between the collector and horizontal axis. the absorber used in the collector can get the most efficient energy when it is mounted as the collector axis which is exactly perpendicular to the sun rays. the angle of sun rays changes related to hour and seasonal time, so do the angles and the slops. 3.3. maximum velocity it can be observed from the results shown in fig. (25) that the solar intensity increased as a result of time. the maximum velocity of the chimney increased too, as collector angle increases due to changes in the incident angle of the solar radiation and the maximum velocity occur when the collector angle was 30 ° . fig. 6. contours of temperature distribution for solar chimney with solar insolation (300 w/m 2 ) for d=6m, h=6m, θ=0°. fig. 7. contours of velocity distribution for the solar chimney with solar insolation (300 w/m 2 ) for d=6m, h=6m θ=0°. arkan k. al-taaie al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 7989(2016) 84 fig. 8. flow felid of air in solar chimney with solar insolation (300 w/m 2 ) for d=6m, h=6m, θ=0°. fig. 9. contours of temperature distribution for solar chimney with solar insolation (900 w/m 2 ) for d=6m, h=6m, θ=0°. fig. 10. contours of velocity distribution for solar chimney with solar insolation (900 w/m 2 ) for d=6m, h=6m, θ=0°. fig. 11. flow felid of air in solar chimney with solar insolation (900 w/m 2 ) for d=6m, h=6m, θ=0°. fig. 12. contours of temperature distribution for solar chimney with solar insolation (300 w/m 2 ) for d=6m, h=6m, θ =15°. fig .13. contours of velocity distribution for solar chimney with solar insolation (300 w/m 2 ) for d=6m, h=6m, θ=15°. arkan k. al-taaie al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 7989(2016) 85 fig. 14. flow felid of air in solar chimney with solar insolation (300 w/m 2 ) for d=6m, h=6m, θ=15. fig. 17. flow felid of air in solar chimney with solar insolation (900 w/m 2 ) for d=6m, h=6m, θ =15°. fig. 15. contours of temperature distribution for solar chimney with solar insolation (900 w/m 2 ) for d=6m, h=6m, θ =15°. fig. 16. contours of velocity distribution for solar chimney with solar insolation (900 w/m 2 ) for d=6m, h=6m, θ =15°. fig. 18. contours of temperature distribution for solar chimney with solar insolation (300 w/m 2 ) for d=6m, h=6m, θ =30°. fig .19. contours of velocity distribution for solar chimney with solar insolation (300 w/m 2 ) for d=6m, h=6m, θ =30°. arkan k. al-taaie al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 7989(2016) 86 fig. 24. the effect of collector angle on maximum temperature at difference solar insolation for d =6m. fig. 25. the effect of collector angle on updraft velocity at chimney top at different solar insolation for d =6m. fig. 20. flow felid of air in solar chimney with solar insolation (300 w/m 2 ) for d=6m, h=6m, θ =30°. fig. 21.contours of temperature distribution for solar chimney with solar insolation (900 w/m 2 ) for d=6m, h=6m, θ =30°. fig. 22. contours of velocity distribution for solar chimney with solar insolation (900 w/m 2 ) for d=6m, h=6m, θ =30°. fig. 23. flow felid of air in solar chimney with solar insolation (900 w/m 2 ) for d=6m, h=6m, θ= 30°. arkan k. al-taaie al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 7989(2016) 87 4. conclution a numerical model for the sloped solar chimney power plant is proposed. the model includes a flow detail inside a collector and chimney. numerical simulations were conducted in order to evaluate the performance of sloped solar chimney power plants. the relationships between the collector angle, the temperature rise across the collector and velocity at chimney are presented. this observation would be useful in the preliminary plant design. the results show: 1. the numerical results of this study have a good agreement with the numerical results of [20] at the same conditions and (θ=0°). 2. the temperature increases with the collector tile angle increase at solar intensity times (7:30,8:15,9 and 10 am) but decrease at 12:30 pm). 3. the velocity of air increase as collector angle increase and maximum velocity occurs at collector angle 30°. 4. both, maximum air temperature and exit air velocity were at solar radiation intensity; 900 w/m2. 5. the cost for constructing a chimney structure can be reduced as a result of reduction in the chimney height. 6. under the iraq weather radiation conditions, large scale solar chimney in iraq is recommended and use the hills and mountains that are available to build these plants. symbols and acronyms symbol description unit d diameter of absorbing ground m g gravitational acceleration m/s 2 h chimney height m h heat transfer coefficient w/m 2 k i solar radiation w/m 2 k turbulent kinetic energy m 2 /s 2 l periphery height of the collector: 0.1 m p pressure pa r radius m s general source term t temperature k° tmax maximum temperature k° t time s u , v fluctuation of mean velocities m/s u,v,w time-average velocity m/s u, v,w velocity components (x,y&z) direction m/s ∆ differentive α absorbtance ∂ partial derivative ε rate of dissipation of kinetic energy m 2 /s 2 θ angle degree ρ fluid density kg/m 3  general dependent variable μ dynamic viscosity n.s/m 2 t  turbulent viscosity n.s/m 2 π pi o ambient 5. references [1] atit, k.and tawit, c.,” accuracy of theoretical models in the prediction of solar chimney performance”, solar energy. vol. 83, pp. (1764-1771), 2009. [2] schlaich j., “the solar chimney”, edition axel menges, stuttgart, germany, 1995. [3] pretorius j.p., kr ِ ger d.g., “solar chimney power plant performance”, j. sol. energy eng. vol.128, 2006,pp 302–311. [4] lorente s, koonsrisuk a, bejan a. “constructal distribution of solar chimney power plants few large and many small”. international journal of green energy 2010;7(6):pp. 577-592. [5] rohmann m. “solar chimney power plant”. bochum university of applied sciences; 2000. [6] “enviromission’s solar tower of power”, http://seekingalpha.com/article/14935enviromission-s-solar-tower-of-power; 2006. [7] schlaich j. “the solar chimney ” stuttgart, germany: edition axel menges; 1995. [8] schlaich j, bergermann r, schiel w, “weinrebe g. sustainable electricity generation with solar updraft towers”. structural engineering international 2004;14(3):,pp. 225-229. [9] fluri tp, pretorius jp, van dyk c, von backström tw, kröger dg, van zijl gpag. arkan k. al-taaie al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 7989(2016) 88 “cost analysis of solar chimney power plants. solar energy” 2009;83(2):,pp. 246256. [10] nizetic s, ninic n, klarin b. “analysis and feasibility of implementing solar chimney power plants in the mediterranean region. energy 2008;33(11):,pp.1680-1690. [11] zhou xp, yang jk, wang j, xiao b. “novel concept for producing energy integrating a solar collector with a man made mountain hollow”. energy conversion and management 2009;50(3):pp. 847-854. [12] papageorgiou c. “floating solar chimney technology". in: rugescu rd, editor.solar energy. intech; 2010. [13] bilgen e, rheault j. “solar chimney power plants for high latitudes”. solar energy 2005;79(5):,pp. 449-458. [14] cao f, zhao l, guo l.” simulation of a sloped solar chimney power plant in lanzhou”. energy conversion and management 2011;52(6):,pp. 2360-2366. [15] panse sv, jadhav as, gudekar as, joshi jb. “inclined solar chimney for power production”. energy conversion and management 2011;52(10):,pp. 3096-3102. [16] jianhua f., louise j.and simon f.,” flow distribution in a solar collector panel with horizontally inclined absorber strips”, http://www.sciencedirect.com, solar energy, vol. 81, pp. (1501–1511),2007. [17] launder, b. e. and spalding, d. b., "lectures in mathematical models of turbulence", academic press, london, england, 1972. [18] john a. duffie,”solar engineering of thermal processes” , book, john wiley and sons , inc.,second edition, 1980. [19] ming t., liu w., and xu g..” analytical and numerical investigation of the solar chimney power plant systems”, international journal of energy research, vol. 30, issue 11, pp. ( 861–873), september 2006. [20] rafah a. n.,”numerical prediction of a solar chimney performance using cfd technique” ,ph.d. thesis submitted to electromechanical engineering department university of technology baghdad, 2007. 2016)) 7989، صفحت 2، العذد12دجلت الخىارسهي الهٌذسيت الوجلم اركاى خلخال حسيي 89 القذرة لتىليذ شوسيت هذخٌت هٌظىهت في الجزياى سلىك ساويت الوجوع على لتاثيز رقويت ًوذجت ***جبيز جاسن عباس **هحوذ شاتي وحيذ *حسيي خلخال اركاى اىرنْ٘ى٘جٍح اىجاٍؼح/ ٌحاىٍَناٍّل ْٕذسحاه قسٌ** ،* ٗاسػ ٍؼحجا/ ٌحاىٍَناٍّل ْٕذسحاه قسٌ*** abbaskut72@yahoo.com.au :االىنرشًّٗ اىثشٌذ* الخالصت حٍث ،داىح ىيَذخْح ٗصفٔتضاٌٗح ٗاىزي ٌَنِ سً ٍائالاُ ّظاً اىَذخْح اىشَسٍح اىَائو ػثاسج ػِ ٍذخْح قذسج شَسٍح ٌنُ٘ فٍٖا ٗظغ اىَجَغ اىشٌ اىطاقح ٗاالشؼاع ذٌ حو ٍؼادالخ االسرَشاسٌح ٗاىضخٌ ٗ.ٍذخْحخفٍط ميفح اّشاء اىَذخْح ٗرىل تسثة اىرخفٍط اىزي س٘ف ٌحصو فً اسذفاع اهتاالٍناُ خ اظطشاتً ٍٗسرقش ،ثالثً االتؼاد،غاغً ضفً ٕزٓ اىذساسح ذٌ اخرثاس اداء اىَذخْح اىشَسٍح اىَائيح خاله جشٌاُ الاُ.fluent (14)اىشَسً تاسرخذاً تشّاٍج حٍث ماّد اتؼاد اىَذخْح اىشَسٍح االسذفاع ،اىؼشاق -ج اىشَسٍح ذحيٍيٍا فً اج٘اء تغذادُٗراك ىحساب اداء اىَذخ k-εاالظطشاتً حٍث ذٌ االسرؼاّح تاىَ٘دٌو ٗ 600ٗ 450ٗ 300)شذج االشؼاع اىشَسً ،ٍخريفح اخرثاس ظشٗفً ٗرىل ػْذ 0.1ً ٗاسذفاع ٍذخو اىَجَغ 0.3قطش اىَذخْح ،6ًقطش اىَجَغ ،ً 6 ىرً ذ٘صو ىٖا اىثحث ٕ٘ اىراثٍش اىنثٍش ىرغٍش صاٌٗح اىَجَغ ٍِ اتشص اىْرائج ا (°0 ,°15 ,°30)ٗػْذ صٌٗا ٍٍو ٍخريفح ىيَجَغ 2ً/ٗاغ ( 900ٗ 750 30°صٌادج صاٌٗح ٍٍالُ اىَجَغ حث ذصو اىى اقصى قٍَٔ ػْذ صاٌٗح حٍث ّالحع اصدٌاد سشػح اىٖ٘اء داخو اىَذخْح ب.اىشَسً ػيى اداء اىَذخْح اىشَسٍح ٗاىَْاظشج ىشذج االشؼاع اىشَسً ٗذقو (ق ظ 7:30,8:15,9,10)ذٌ اىر٘صو مزىل اُ دسجاخ اىحشاسج ذضداد تضٌادج صاٌٗح اىَجَغ اىشَسً فً االٗقاخ ، . ٕزا اىْ٘ع ٍِ االّظَحتٍْد ٕزٓ اىذساسح اٌعا اُ اج٘اء اىؼشاق ٍالئَح ه. ب ظ( 12:30)ػْذ mailto:kut72@yahoo.com.au*البريد mailto:kut72@yahoo.com.au*البريد 7279 al-khwarizmi engineering journal al-khwarizmi engineering journal,vol. 12, no. 3, p.p. 7279 (2016) effect of nano powder on mechanical and physical properties of glass fiber reinforced epoxy composite aseel basim abdul-hussein* fadhel abbas hashim** tamara raad kadhim*** *,**,***department of materials engineering/ university of technology *email: dr.material@yahoo.com (received 16 april 2015; accepted 12 january 2016) abstract fiber reinforced polymer composite is an important material for structural application. the diversified application of frp composite has taken center of attraction for interdisciplinary research. however, improvements on mechanical properties of this class of materials are still under research for different applications. in this paper we have modified the epoxy matrix by al2o3, sio2 and tio2 nano particles in glass fiber/epoxy composite to improve the mechanical and physical properties. the composites are fabricated by hand lay-up method. it is observed that mechanical properties like flexural strength, hardness are more in case of sio2 modified epoxy composite compare to other nano modifiers, were physical properties like density, water absorption are more in case of tio2 modified epoxy composite. this may be because of smaller particle size of silica compare to others. key word: density, water absorption, hardness, flexural strength, glass fibers, composites. 1. introduction development of new composite materials or modification of existing composite material is the real challenge for most of the materials engineers. epoxy base matrix composite has tremendous potential to substitute the traditional metallic materials. polymer matrix modification is one of the approaches to develop new class of polymer structural materials. this modification can be done by addition of different ceramic powders of different sizes to achieve the required mechanical properties. mcgrath et al. (2008) studied the effect of alumina powder in epoxy on mechanical properties. they found that there is a little effect on change in particle size, shape and size distribution on final properties. however the resin crosslink density and filler loading were the most critical variable, which may change all properties [1]. l.merad.et.al, have study the mechanical properties of epoxy resin reinforced with tio2 nanoparticles. these nanoparticle are 21nm in diameter and volume fraction (o.5, 1, 5 and 20%).the results shown that the mechanical properties like hardness and tensile strength higher than net epoxy and increased with increase addition of tio2 nanoparticles [2]. ikram .et. al, have studied mechanical properties of micro and nano tio2/ epoxy composites, with epoxy volume fraction (1,2,3,4,5,6,7,10,15,20) of microparticles tio2 (50 µm) and nanoparticle tio2 (50nm) the flexural strength, young modulus and fracture toughness of nanocomposites were increased at low volume fraction (less than 7 vol%). at higher volume fraction both flexural strength and fracture toughness decrease while young modulus still higher than that of epoxy. the flexural strength and fracture toughness of epoxy-microcomposites decreases with increasing the volume fraction of tio2 microparticles specially at high volume fraction while young modulus increases with increasing the volume fraction [3]. dr.falak o.abas,raghad o.abas and sarmad i. aseel basim abdul-hussein al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 7279(2016) 73 ibrahim have studied the properties and behavior of particles on (glass, carbon, and kevlar fiber) reinforced polyester composites. the effect of alumina (al2o3) and silicon carbide (sic) particles ceramic polyester composites are investigated at different additive ratios as (0.2, 0.4, 0.6, 0.8, 1.0%) volume fraction. comparative analysis show that the bending distortion, hardness, and impact resistance are affected by the type and content of filler particles, where both impact and hardness is increased with increasing volume fraction specially in case of (0.5%) volume fraction for both filler particles and decreased for bending distortion specially in case of glass fiber/ polyester at (0.5%) volume fraction for both filler particles [4]. ramish k.et.al, have study the effect of epoxy modifiers (al2o3, sio2, tio2) on mechanical performance of epoxy/glass fiber hybrid composite. the results shown that mechanical properties like flexural strength, and flexural modulus are more in case of sio2 modified epoxy composite compare to other micro modifier. this is may be because of smaller particle size of silica compare to other. alumina modified epoxy composite increase the hardness and impact energy compare to other modifiers [5]. 2. experimental procedure 2.1. materials in our study, commercially available al2o3 (45 nm), sio2 (38 nm), tio2 (47 nm) particles are used to modify the epoxy matrix. nano fillers of al2o3, sio2 and tio2 were purchased from nano shell company. commercially available woven roving fabric e-glass fiber from the tenax company, england. the epoxy which is used was euxit (50) base as the matrix from the (al-rakaez building materials) made in egypt in the form of transparent viscous liquid at room temperature which is a thermally hardened polymers (thermosets) with a density of (1.05 gm / cm3) 2.2 fabrication of hybrid frp composite there are three types of hybrid frp composite with different fillers are fabricated using hand layup method. the volume percentage of epoxy, fiber, filler and hardener are fixed and designations of the composites are reported in table -1. where a, s and t indicate al2o3, sio2 and tio2 modified frp composite. adding the powder intermittently into the mixture and stirring it for a period of (1015) minutes to obtain homogeneity. a rise in the temperature of the mixture will result as an indication to the beginning of the interaction process. it is very important that the mixture must have a good viscosity for the purpose of protecting the particles from precipitation which may result in the heterogeneity of the mixture that leads to the agglomeration after hardening. pouring the mixture into the mould, then putting the glass fiber mat into the mould and continuing of mixture pouring until it covers the entire mat. pressing the mixture with an appropriate load. for the purpose of completing the process of hardening, finally is leaving the sample in the mould for a period of (24) hour at room temperature. samples are then extracted from the mould and then heat treated in an oven at (60ċ) for a period of (60) minutes [6]. this process is very important for the purpose of obtaining the best cross linking between polymeric chains, and to remove the stresses generated from the preparation process and complete the full hardening of the samples. fig. 1 shows the shape of the prepared mould. table 1, designation and composition of composites fig. 1. the shape of the prepared mould. 3. results and discussion 3.1. xrd of powder the x-ray powder diffraction patterns are shown in fig. (2).for three materials, all major designation of composites composition a epoxy + 3% g.f + 2, 4 and 6 % al 2o3 s epoxy + 3 % g.f +2, 4 and 6% sio2 t epoxy+ 3% g.f+2, 4 and 6%tio2 aseel basim abdul-hussein al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 7279(2016) 74 peaks were assigned to the crystalline structure. al 2o3 was hexagonal structure, sio2 was cubic structure, and tio2 was tetragonal structure. fig. 2. the xed of nano powder. 3.2. hardness (shore d) this test is performed by using hardness (shore d) and according to (astm di-2240) standard at room temperature. samples have been cut into a diameter of (40mm) and a thickness of (5mm) [7]. table (2) shows the values of hardness for the prepared (pure epoxy, epoxy +3% glass fiber and nano) composites. table 2, hardness of prepared composites. types of composites hardness shore d ep 77 ep +3% g.f 78 ep + 3%g.f+2% sio2 81.5 ep + 3%g.f+4% sio2 83.7 ep + 3%g.f+6% sio2 84.8 ep + 3%g.f+2% al2o3 81.2 ep + 3%g.f+4% al2o3 83.2 ep + 3%g.f+6% al2o3 84.3 ep + 3%g.f+2% tio2 80.5 ep + 3%g.f+4% tio2 82.7 ep + 3%g.f+6% tio2 83.9 from fig. (3) it is clear that there is a pronounced effect of the addition of 3% glass fiber volume fraction percents on the hardness of the material. this may be due to the fact that the hardness is generally considered to be a property of the surface therefore this behavior of hardness is expected. and can be seen from figure a pronounced effect of the addition of 3% glass fiber with 2%, 4%and 6% volume fraction from (nano powder) percents on the hardness of the material. it can be seen that the hardness increases with increasing volume fraction. adding the filler particles will raise the materials hardness due to increasing in material resistance against the plastic deformation. result had revealed that the hardness of pure epoxy alone was (77 shore d) compared to maximum value (84) at volume fraction of (6% sio2) with particle size is (38nm). the reason of the increase in hardness is that sio2 contains an elements harder than the pure epoxy that lead to an increase in hardness. these results become match with our work because the sio2 have larger surface area and smaller particle size than (al2o3and tio2). fig. 3.hardness of papered composite. al2o3 sio2 tio2 aseel basim abdul-hussein al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 7279(2016) 75 3.3. flexural strength this test is performed according to (astm d790) at room temperature. samples have been cut into the dimensions (80*3.2*2.5) mm [8]. the flexural strength are calculated according to the equations [9] … (1) where f.s flexural strength (mpa). p force at fracture (n). l length of the sample (mm). b thickness (mm). d width (mm). table (3) shows the values of flexural strength for all prepared composites. table 3, flexural strength of prepared composites. fig.4.shows flexural strength of all prepared composites. it can be noted from this figure that the addition of 3% glass fiber with 2%, 4% and 6% volume fraction from nano powder has a significant effect on the flexural strength of the composite material. and, the flexural strength increases with increasing volume fraction and decreasing of the particle size. the flexural strength of pure epoxy reference was (149 mpa), and then an increasing was observed with increasing in volume fraction till it reached to its maximum value of (375 mpa) by the addition of (3% glass fiber) and volume fraction of (6% sio2) with particle size is (38nm) which is (151%) higher than epoxy alone. these results match with the present because the sio2 has particle size smaller than (al2o3 and tio2), this can be attributed to ductility of sio2 which is reducing the brittleness of composite. fig. 4. flextural strength of papered composite. 3.4. true density this test is performed according to (astm d792) standard at the room temperature [9].the samples were cut into a diameter of 40 mm and a thickness of 5 mm the measured density (ρt) is calculated from the method of immersion in water using the following relationship [10]. ρt= (wd /ws-wn)*d … (2) where: ρt measured density or bulk density (gm/cm3). d density of distilled water (1 gm/cm3). wd dry weight of sample (gm). wn weight of the sample, a commentator and submerged with water (gm). ws weight of the sample is saturated with water (gm). table (4) shows the values of density for the prepared composites. table 4, density of prepared composites. types of composites true density ep 1.05 ep +3% g.f 1.080 ep + 3%g.f+2% sio2 1.122 ep + 3%g.f+4% sio2 1.155 ep + 3% g.f+6% sio2 1.185 ep + 3%g.f+2% al2o3 1.130 ep + 3%g.f+4% al2o3 1.165 ep + 3%g.f+6% al2o3 1.197 ep + 3%g.f+2% tio2 1.140 ep + 3%g.f+4% tio2 1.178 ep + 3%g.f+6% tio2 1.215 fig.5 show the true density for prepared composites. in fig. 5 can be seen the higher true density has been found to be for the specimen (epoxy +3%g.f+6%tio2) due the tio2 powder have density higher than individual density when types of composites flexural strength ep 149 ep +3% g.f 158 ep + 3%g.f+2% sio2 325 ep + 3%g.f+4% sio2 349 ep + 3% g.f+6% sio2 375 ep + 3%g.f+2% al2o3 310 ep + 3%g.f+4% al2o3 342 ep + 3%g.f+6% al2o3 362 ep + 3%g.f+2% tio2 290 ep + 3%g.f+4% tio2 337 ep + 3%g.f+6% tio2 355 120 190 260 330 400 f le x tu ra l s tr e n g h t (m p a ) type of composite flextural st renght aseel basim abdul-hussein al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 7279(2016) 76 compared with composite (al2o3 and sio2) nano powder. where the density of tio2 (4.25 gm/cm3), al2o3 (4.05 gm/cm3) and sio2 (2.7 gm/cm3) .when comparing the value of true density nano composite with measured density of (pure epoxy) can be seen higher than because the additions of reinforcement (tio2, al2o3, sio2) nano powder that have higher density than matrix (pure epoxy).where density of pure epoxy (1.05 gm/cm3). fig. 5. true density of papered composite. 3.5. water absorption this test is performed according to (astm d 570) standard at room temperature [11]. samples have been cut into a diameter of (40mm) and a thickness of (5mm). the mechanism of water absorption is explained to be the direct uptake and flow of water by capillary and transport along the reinforcement-matrix interface [12]. water absorption percentage is calculated using (archimedes base) according the following formula [13]. … (3) where m (%) water absorption percentage. mo mass of specimen before immersion (g). mt: mass of specimen after immersion for seven days (g). table (5) shows the values of water absorption for the prepared composites. table 5, water absorption of prepared composites. types of composites water absorption ep 0.120 ep +3% g.f 0.195 ep + 3%g.f+2% sio2 0.215 ep + 3%g.f+4% sio2 0.313 ep + 3% g.f+6% sio2 0.364 ep + 3%g.f+2% al2o3 0.240 ep + 3%g.f+4% al2o3 0.325 ep + 3%g.f+6% al2o3 0.378 ep + 3%g.f+2% tio2 0.275 ep + 3%g.f+4% tio2 0.340 ep + 3%g.f+6% tio2 0.385 in fig. 6 shows the water absorption of all prepared composites can be seen the specimen (epoxy +3%g.f) have higher water absorption than specimen (pure epoxy), the increasing water absorption percentage with increasing volume fraction of fiber depends on the rule of mixture theory where fiber have a higher water absorption percentage than specimen pure epoxy [14]. the water absorption attacked the fiber-matrix interface, causing de-bonding of the fiber and the matrix. the failures of the composite materials were due to voids [15]. and nano composites given higher water absorption percentage than specimen pure epoxy and specimen (epoxy +3%glass fiber) composites. the higher water absorption percentage of nano composite has been found to specimen (epoxy +3%g.f+6%tio2) while the specimen (epoxy + 3%g.f+6% sio2) have lower than specimen of (al2o3 and tio2) at the volume fraction (3%) of glass fiber and (6% ) volume fraction of filler particles ( nano powder ), and the specimens (epoxy +3%g.f+2% tio2), (epoxy +3%g.f+4% tio2)have higher water absorption percentage while the specimen (epoxy + 3%g.f+2% sio2), (epoxy + 3%g.f+4% sio2) have lower than specimen of (al2o3 and tio2) at the volume fraction (3% ) of glass fiber and (2%,4%) volume fraction of filler particles (nano powder ).in this work the specimens of composite material filled with larger particles show a higher water absorption percentage when compared with the specimens of composite material filled with small particles because the saturation level of fillers matrix composition influenced by agglomeration that will affect the water absorption percentage of the composite material. the mean particle size of the (sio2) is (38nm) while mean particle size of the (al2o3) is (45 nm) and mean particle size of the (tio2) is (48nm). aseel basim abdul-hussein al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 7279(2016) 77 fig. 6.water absorption of papered composite. 3. conclusion non –reinforced pure epoxy has lower physical and mechanical properties than (epoxy+3%glass fiber) composites and nano composites. the values of measured density are lower than nano composite with 3% glass fiber and 6% nano powder have the higher density when compared with other composites. nano composite with (epoxy +3% glass fiber +6%tio2) has the maximum density of (1.215) (gm/cm3) when compared with other composites. the values of water absorption of specimen (pure epoxy) lower than specimen (epoxy +3% glass fibers). nano composite with 3% glass fiber and 6% nano powder have the higher water absorption when compared with specimen (pure epoxy) and specimen (epoxy +3% glass fibers) composites. nano composite with (epoxy +3% glass fibers +6%tio2) has the maximum water absorption of (0.385%) result shows that the best hardness value was (84.8 shore d), flexural strength (375mpa) at volume fraction of (3%glass fiber) with (6% sio2). 4. references [1] mcgrath laura m. , richard s. parnas , saskia h. king , john l. schroeder , daniel a. fischer , joseph l. lenhart, 2008. investigation of the thermal, mechanical, and fracture properties of alumina epoxy composites, polymer 49, 999-1014. [2] l.merad, b. benyoucef,m.j.m abadie, j.p charles,"characterization and mechanical properties of epoxy resin reinforced with tio2 nanoparticles", journal and engineering and applied sciences,(2011), no. 3, pp.205-209. [3] ikram a. al-ajaj, muhannad m. abd and harith i. jaffer,"mechanical properties of micro and nano tio2/epoxy composites", international journal of mining & mechanical engineering, (2013), no. 2, vol.1, pp.2320-4060. [4] dr.falak o.abas,raghad o.abas and sarmad i. i brahim , " a comparison study of different ceramic filler on mechanical and thermal properties of glass, carbon, kevlar / polyester composites", eng. & tech. journal, (2010), no. 12, vol. 28, pp. 2469. [5] ramesh k. nayak , alina dasha and .c.ray,"effect of epoxy modifiers (al2o3, sio2, tio2) on mechanical performance of epoxy/glass fiber hybrid composites", elsevier journal(2014),vol.6,pp.13591364,6 (doi:10.1016/j.mspro.2014.07.115). [6] felix k., sylvester a. and edmund a.,"storage and handling techniques of maize and groundnut", senra academic publishers, burnaby, british columbia, no.3, vol.6, pp.2122, (2012). [7] annual book of astm standard "standard test method for plastics properties durometer hardness d 2240", vol. 09.01, (1988). [8] annual book of astm standard, "standard test methods for flexural properties of unreinforced and reinforced plastics ", d 79086, vol. 10.01, (1986). [9] m. a. meyers & k. k. chawla," mechanical behavior of materials", prentice hall, inc., usa, (1999), pp. 644. [10] annual book of astm standard, "density and specific gravity (relative density) of plastics by displacement1". [11] annual book of astm standard, "standard test method for water absorption of plastics d 57098", vol. 08.01, (2005). [12] mohammed ismail, suresha bheemappa and n. rajendra, "investigations on mechanical and erosive wear behaviour of cenosphere filled carbon-epoxy composites", international conference on mechanical, automotive and materials engineering, dubai,(2012) ,pp.209. [13] m.h.a ghani & s. ahmad, "the comparison of water absorption analysis between counter rotating and corotating twin-screw extruders with different antioxidants content in wood plastic composites",(2011), vol.20, pp. 2. 0 0.5 w a te r a b so rp ti o n ( % ) type of composite absorption aseel basim abdul-hussein al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 7279(2016) 78 [14] d. chandramohan, and j. bharanichandar " narural fibre reinforced polymer composites for automobile accessories ", american journal of environmental science , (2013), no.6 ,vol. 9, pp.494-504, (doi:10.3844/ajessp.2013.494.504). [15] waffaa abed alkazem zkaer " determination of some mechanical properties of unsaturated polyester reinforced with glass fiber and plam fiber"eng.&tech.journal,, (2011) ,no.16,vol.29,pp.3313-3319 � 3، ا���د�12ا���ارز�� ا����� � ا������� � � ا� � �ا� � ���� ��� ،2016( 7279( 79 234 ' ا����1 0 ا���,�(/ ��. ا���اص ا�� +�, + � وا�� #(�) � ����اد ا��'&�� ا������ ��%� �ف ا�#"�ج � � *** ر�� ��4ره **ھ��8 ���س �5�6* ا� � ���� ��� ا� ��اد *** ،**،*��/ %$# ھ! �� ا&'���!()�� ا*+,-� ا dr.material@yahoo.com : ا�314 ا2�)(1و/.* ا����� ���ون ا��واد ا���را��� �ن را�"! ا �و��� ���ده ا��س . �م �� ھذا ا���ث ��� ر �واد ��را��� �وا�ط� طر �� ا��و��� ا� دو � ودرا�� ������� ق �% ٦ و% ٤و %��٢ر �'�� �ن أ� �ف ا�ز'�ج ���دة ��و � و % ٣و���� � او�� د ، sio2 ناو�� د ا��0 �و، al2o3 او�� د ا ��" وم( "�"و وم"�� "���! ان اظ�رت ا�. ��ص ا��8ده و���و�� ا "�"�ء وا���6�� وا ����� � �5�0ف 4ن 3 ��� ��ل "وع �ن ا��واد ا���را��� ا�"�"و � .) tio2 ا�� ��ن ا�"���! اظ�رت ��ن ا���6�� �زاد �? ز �د ا���ر ا��'�� .ا �و��� < ر ا���وى ��0ك �واص ا3ل �ن ا��واد ا���را��� ��4"د ا'راء ا����رات ا���6 �� .وا����� � ا���ء وا��8دة و���و�� ا "�"�ء ��"�� �زداد �? ز �دة ا���ر ا��'�� �? ا�@ر �'م �� 1-10احمد وسمير وحسام al-khwarizmi engineering journal,vol. 13, no. 1, p.p. 1 the effects of long-term operation material properties of ahmed naif al-khazraji husam ahmed al *,**,*** department of *email: ** email: *** email: (received 3 august https://doi.org/10.22153/kej.2017.11.00 abstract changes in mechanical properties of material as a result of service in different conditions can be provided by mechanical testing to assist the estimation of current internal situation of these materials, or the degree of deterioration may exist in furnaces serviced at high temperature and exceed their design life. because of the rarity works on austenitic stainless steel material type aisi 321h, in this work, ultimate tensile strength, yield strength, elongation, hardness, and absorbed energy by impact are samples of tubes are extracted from furnace belong to used to make comparisons between these properties. temperature increases; the trend of properties decreasing for the samples of un used material. the trend of stress-strain curve will not change due to elevated temperature exposure for long time of service, except the yield strength will be higher in this diagram. the yield strength increased under these conditions, but the ability of material which is elongated will respectively when the material is aged for long time under effect of keywords: hardness, impact, mechanical properties tube furnace. 1. introduction austenitic stainless steels are widely used in engineering applications; these types of alloy selected to serve at high temperature due to high tensile strength and good creep resistance furnaces in reforming units are the core of these units provided by heat to produce hydrogen from hydrocarbons. the nominal life design for furnaces is 100000hr on the basis of standard 530[1]. assessment of damage in these furnaces is an important factor in determining their remaining safe life. components in service at elevated temperatures for long term can fail due to excessive creep deformation or cracking. khwarizmi engineering journal,vol. 13, no. 1, p.p. 110 (2017) term operation and high temperature of austenitic stainless steel type 321h khazraji* samir ali amin** husam ahmed al-warmizyari*** department of mechanical engineering/ university of technology email:dr_ahmed53@yahoo.com email: alrabiee2002@yahoo.com email: husamahmed75@yahoo.com august 2016; accepted 2 november 2016) https://doi.org/10.22153/kej.2017.11.005 changes in mechanical properties of material as a result of service in different conditions can be provided by mechanical testing to assist the estimation of current internal situation of these materials, or the degree of deterioration s serviced at high temperature and exceed their design life. because of the rarity works on austenitic stainless steel material type aisi 321h, in this work, ultimate tensile strength, yield strength, elongation, evaluated based on experimental data obtained from mechanical testing. samples of tubes are extracted from furnace belong to hydrotreaterunit, also samples from un-used tube material are used to make comparisons between these properties. tensile properties of stainless steel (aisi 321h) were temperature increases; the trend of properties decreasing for the samples of un-used tube material is the same for the ex strain curve will not change due to elevated temperature exposure for long time of will be higher in this diagram. the yield strength increased under these conditions, but elongated will decrease. hardness and absorbed energy increased by 11.28 and 14% l is aged for long time under effect of high temperature accompanied with creep effect mechanical properties, stainless steel 321h, mechanical properties, austenitic stainless steels are widely used in of alloys are due to their high tensile strength and good creep resistance. are the core of these produce hydrogen from design for such standard api ssessment of damage in these furnaces is an important factor in determining their remaining at elevated can fail due to excessive creep deformation or cracking. therefore, improvement of material strength other properties for these components is the key to resist such failures. the assessment of properties, such as hardness, impact energy tensile strength near the end of design life or beyond that is vital to provide a safe working life for the unit and prevent a catastrophic failure hardness measurements are the best ways to detect if there are metallurgical changes recent developments in the technique have shown that it can be used in a predictive sense to estimate the remnant life based approach is used to evaluate strength of superheater tubes of boiler impact test also has been used in testing of steel al-khwarizmi engineering journal temperature on type 321h changes in mechanical properties of material as a result of service in different conditions can be provided by mechanical testing to assist the estimation of current internal situation of these materials, or the degree of deterioration s serviced at high temperature and exceed their design life. because of the rarity works on austenitic stainless steel material type aisi 321h, in this work, ultimate tensile strength, yield strength, elongation, evaluated based on experimental data obtained from mechanical testing. used tube material are were decreased as used tube material is the same for the exstrain curve will not change due to elevated temperature exposure for long time of will be higher in this diagram. the yield strength increased under these conditions, but by 11.28 and 14% accompanied with creep effect. tensile strength, therefore, improvement of material strength and for these components is the key to e assessment of material impact energy, and near the end of design life or provide a safe working life prevent a catastrophic failure. hardness measurements are the best ways to detect if there are metallurgical changes [2,3]. ecent developments in the technique of hardness shown that it can be used in a predictive remnant life [4], a hardness based approach is used to evaluate the creep of boilers [5]. the n testing of steel pdf created with pdffactory trial version www.pdffactory.com https://doi.org/10.22153/kej.2017.11.00 mailto:dr_ahmed53@yahoo.com mailto:alrabiee2002@yahoo.com mailto:husamahmed75@yahoo.com https://doi.org/10.22153/kej.2017.11.00 http://www.pdffactory.com http://www.pdffactory.com ahmed naif al-khazraji al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 110 (2017) 2 products which is related to the behavior of metal, and in some cases, making the tests at properly chosen temperatures other than room temperature [6]. the remaining life of furnaces tubes can be predicted based on fracture toughness and mechanical properties, also a suggestion to pay more attention to avoid the excessive impact during starting up and shutdowns because of the decrease in material ductility [7]. a comparison of both mechanical properties at different temperatures and the roles of these properties to resist creep [8], can be useful to give good indications for the degree of internal damage due to prolonged exposure to temperature, when these comparisons are made between the un-used and ex-used material. austenitic stainless steel aisi 321 is stabilized by titanium addition. this grade of steel is used in engineering applications under high temperature, because of its high strength and good creep resistance. while, stainless steel aisi 321h is modified to stainless steel aisi 321 with higher carbon contains, it was developed to enhance the creep resistance and the higher strength at temperature above 537oc. many researches cover the stainless steel material type 321 from different viewpoints [9, 10, 11, 12, 13, 14, 15], on the other hand, there is a gap in the published researches about the modified stainless steel material type 321h. because of the rare work on austenitic stainless steel material type 321h, the present work investigates a furnace tube (o.d. 141.3 mm, thickness 6.55 mm) made from this type of steel and served in complex reformer/naphtha hydrotreater unit for more than 290000hr, the design tube wall temperature is 570oc. this investigation uses the mechanical properties, such as hardness, impact energy, yield strength, and tensile strength at different temperatures to make a comparison between an ex-used tube with unused one of the same dimensions and material. tensile tests were done at four different temperatures 25oc, 300oc, 500oc, and 700oc, while impact tests were conducted at room temperature and at the maximum service temperature 466oc. 2. experimentation 2.1. chemical analysis of tube samples in this work, two different ages of austenitic stainless steel samples were investigated, namely un-used ss321h and ex-used ss321h. the exused samples are belongs to a stripper reboiler furnace / naphtha hydrotreater unit, these samples are made according to astm standard a-312tp321h. their compositions with the limitations for the elements percentage according to the standard are given in table 1. 2.2. mechanical tests macro-hardness according to vickers scale were done using a device (nemesis 9000) with a load of 10 kgf, the tests are supported by the relevant standard iso-6507-1[17]. groups of five hardness measurements were taken at room temperature for each sample (un-used material and ex-used material). samples of these tubes were cut and prepared according to the requirement of adopted standard. any individual of hardness measurement made in the lab will lack perfect precision that often leads to take multiple measurements. so, no one of these measurements is likely to be more precise than any other, this group of values will cluster about the true value to be measured. this distribution of data values is often represented by showing a single data point, representing the mean value of the data, and error bars to represent the overall distribution of the data. the standard error for hardness measurement was calculated (2.5008, 0.8792) for samples of the materials un-used and ex-used, respectively. standard charpy v-notch impact specimens were prepared according to the american standard astm e23[6]. due to tube thickness restriction, specimens with sub size dimensions were prepared, as shown in figure 1. all impact specimens were tested using a universal impact test machine (brooks – model it3u). the impact tests for specimens of each type of material were performed in two different temperatures, at room temperature and at furnace service temperature (maximum wall temperature) 466oc. pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com ahmed naif al-khazraji al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 110 (2017) 3 table 1, composition of material tubes samples. materials c si mn ni cr ti p s fe a-312tp321h (standard)[16] 0.040.1 1.0 a 2.0 a 9 –12 17–19 h 0.045a 0.03a rem. un-used tube samples 0.04 0.49 0.61 9.24 15.87 0.29 0.033 0.004 rem. ex-used tube samples 0.061 0.3 1.66 11.34 15.94 0.43 0.016 0.016 rem. a:maximum, h:the titanium content shall be not less than four times the carbon content and not more than 0.60%. table 2, mechanical properties for austenitic stainless steel 321h at different test temperatures. temperature (oc) 25 300 500 700 specimen type un used ex used un used ex used un used ex used un used ex used yield strength0.2% (mpa) 190 219 135 191 109 182 93 153 tensile strength (mpa) 606 584 401 417 381 376 237 242 elongation32% (%) 69 49 40 32 37 28 56 55.6 fig. 1. specimen's classification for impact test. changes in strength between the un-used material and the ex-used one at a temperature range (from room temperature up to 700oc) can be found by performing a uniaxial tensile test using tensile machine "shimadzu ag-25tc". flat dog bone type specimens with thickness 3mm for this purpose were prepared according to the standard, see figure 2. different test machine speeds were used to distinguish between the elastic and plastic zones, also these values are different either at room temperature tensile tests or for hot tensile tests. the values of yield strength (taken at 0.2% engineering strain), tensile strength, and elongation were recorded for each test temperature for both un-used material and exused material of austenitic stainless steel 321h, see table 2. fig. 2. dimensions of flat specimen for the uniaxial tensile test. 3. results and discussion 3.1. hardness behavior as known, the easy way to sense that there is a metallurgical change happened in the metals due to temperature exposure is the hardness pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com ahmed naif al-khazraji al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 110 (2017) 4 measurement, but the behavior of hardness depends on steel alloy, and its carbide type precipitated. as example, the hardness of material a-213t91 decreases during creep at elevated temperature [3]. for austenitic stainless steel type 321h as seen in figure 3, the hardness increased about (11.27%) compared to the un-used material, that raising happen during the material service under operating temperature about 466oc for this long time. it is thought that this increase is related the fine titanium carbide tic precipitated in grains at the temperature range of furnace operation, where the fine tic precipitation increases the hardness of austenitic stainless steel type 321 up to temperature 850oc, while the coarsening of tic precipitation softens this type of stainless steel more than 850oc [9]. fig. 3. comparison between hardness of un-used and ex-used tubes of stainless steel material a312tp321h. 3.2. impact energy a comparison between the results of impact test at room temperature and at 466oc for specimen dimension (10x5x55 mm) can be seen in figures 4 (a) and 4(b) for both un-used and exused stainless steel 321h material. the impact energy value is directly related to the crosssectional area of the specimens, and to make a double check for the accuracy of the measurements, another sub-size dimension (5x5x55 mm) for the specimens with 50% reduction in specimen cross section was used, see figure 4 (c). a. impact test at room temperature for specimens with dimensions 10x5x55 mm b. impact test at temperature 466 oc for specimens with dimensions 10x5x55 mm c. impact test at room temperature for specimens with dimensions 5x5x55 mm fig. 4 impact energy comparison between un-used and ex-used stainless steel tube samples (sa-312tp321h) pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com ahmed naif al-khazraji al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 110 (2017) 5 when stainless steel type 321h is aged for long time under the effect of elevated temperature exposure accompanied with creep effect in general, it shows a rising in bearing energy before break can happen, this can be measured either under room temperature impact test or at elevated temperature test, see figures 4(a) and 4(b), also the reduced specimen size (5x5x55 mm) depicts similar behavior as seen in figure 4(c). this energy increased by a percentage 14% in figures 4(a) and 4(b), as well by about 10% in figure 4(c), this is most likely due to the thermal effect occurred during the material service at the furnace operation temperature. the temperature effect on the amount of the impact energy was also examined for the two types of stainless steel type 321h, the un-used and ex-used material, as shown in figure 5. this figure shows decreases by a percentage about 10% for each type of this material, this is most probably ascribed to the precipitation hardening effect by chromium carbides formation within the structure. this means that this decrease is due to thermal influence only, indicating that operating at this temperature for long period of time leads to increase this absorbed energy. fig. 5. relation between impact energy and test temperature for austenitic stainless steel 321h. 3.3. tensile properties the results of uniaxial tensile tests for austenitic stainless steel type 321h under different test temperatures (25oc, 300oc, 500oc, 700oc) were drawn on the same stress-strain diagram for comparison, the resulted diagram for the un-used material can be seen in figure 6, while figure 7 shows the resulted diagram for the ex-used material. the plastic deformation seems to fade with increased temperature, the maximum stresses decrease with increased temperature for the two types of samples as expected. tensile properties of ss321h, such as 0.2% offsite of yield and tensile strength, generally decrease as temperature increases, as seen in figure 8. the trend of this decreasing in properties for un-used material is the same for the ex-used material. this reduction is related to the formation of carbides at grain boundaries. fig. 6. stress-strain curve under different temperatures for un-used austenitic stainless steel 321h. fig. 7. stress-strain curve under different temperatures for ex-used stainless steel 321h. fig. 8. yield and tensile strength versus temperature for austenitic stainless steel 321h. pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com ahmed naif al-khazraji al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 110 (2017) 6 comparisons were made between the results of uniaxial tensile tests represented by stress-strain curves as shown in figures (9 to 12) for different test temperatures, each diagram compares the tensile properties of stainless steel 321h at specific temperature between the un-used and exused samples. in general, stainless steel 321h lost its ability to elongate, which represents a reflection to the deterioration happened in this material due to the exposure to elevated temperature (466oc) for long time of service. on the contrary, the yield strength 0.2% offset of stainless steel 321h enhanced at each test temperature as seen in table 2, while the curves for each test temperature are in the same trend between the ex-used and un-used stainless steel 321h, but the curves for the ex-used samples are higher than the un-used ones. the ultimate tensile stress of stainless steel 321h is changed after its long service life in this case study for stripper re-boiler furnace under maximum tube wall temperature about 466oc, this change is fluctuating, it is varying in a manner depends on the test temperature, where it is decreased at temperatures 25 and 500oc and increased at temperatures 300oc and 700oc, as shown in table 2 and in figures (9-12). so that, it is not accredited parameter to judge that the deterioration or damage due to high temperature exposure does or doesn't exist in the structure of the material. the stress-strain curves in figures 6 and 7 reveal signs of dynamic strain aging effect for the ss321h material; this is due to alloy content, test temperature, and past service life. the common feature of dynamic strain aging is that it increases the ultimate tensile strength (uts) and causes strengthening in a specific temperature range which depends on the strain rate as shown in table 2 for this material which is aged for long life time; this is repeated for the uniaxial tensile tests at 500oc and at 700oc, figures 10 and 12. the level of strengthening depends on the aging time and on the aging temperature. a typical characteristic of dynamic strain aging is the formation of serrated yielding. this is often called the portevinlechatelier (plc) effect. different serration types of stress-strain curves for the austenitic stainless steel 321h are marked on the curves of figures (9-11). the most common serration types were a, b, and d appeared on the curves up to test temperature 500oc, while at the test temperature 700oc, they didn't appear, because the material at this temperature is near the recovery and recrystallization temperatures which will decrease the dynamic strain aging due to the extermination of dislocations. type a is considered as locking serrations, it is abrupt rise and then drop to a stress level below the general level. type b has an irregular movement and is characterize by small oscillations about the general level of the curve. type d is characterized by plateaus on the curve, it can also appear mixed with the type b [18]. changes in mechanical properties of material as a result of service in different conditions from load, temperature, environment, etc., can be provided easily if we adopt usual examination techniques such uniaxial tensile tests to have a data or figures aid the estimation of the current internal situation of these materials, or the degree of deterioration may exist. 4. conclusions the following results of this work can be used for the tubes of furnaces operated at high temperatures for long time as a supportive technique to give a good indication about the remaining life estimation in short time, which could be used as a routine inspection activity during the period of scheduled shutdowns, especially when the operation life is near or overcome the design life. (i) changes in mechanical properties of material as a result of service in different conditions from load, temperature, environment, etc., can be provided easily if we adopt available examination techniques to have a data or figures assist to estimate the current internal situation of these materials, or the degree of deterioration may exist. (ii) hardness of austenitic stainless steel type 321h increased about (11.28%) during service for long time under temperature about 466oc, this increase is related to chromium carbide cr23c6 and the fine titanium carbide tic precipitated in grains at the temperature range of service. (iii) the absorbed energy due to impact by austenitic stainless steel 321h increased about (14%) when the material is aged for long time under the effect of elevated temperature exposure accompanied with creep effect, this is most likely due to thermal effect happened during material service at the furnace operation temperature. also, this behavior can be recorded by the impact test with different specimens’ dimensions. (iv) the absorbed energy due to impact by austenitic stainless steel 321h decreased about (10%) when the temperature increased up to 466oc, this behavior can be recorded if the sample pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com ahmed naif al-khazraji al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 110 (2017) 7 for impact test is taken from un-used material or ex-used material; this is most probably ascribed to the precipitation hardening effect by chromium carbides formation within the structure. (v) the trend of stress-strain curve of austenitic stainless steel 321h will not change due to the exposure to elevated temperature (466oc) for long time of service and/or creep effect takes place, but the curves will be higher. the yield strength 0.2% offset increased under these conditions, but the ability of material to be elongated under the action of axial load will decrease. the ultimate tensile stress is fluctuating in these conditions and depends on the service temperature. (vi) tensile properties of austenitic stainless steel 321h decrease as the temperature increases, the trend of this decreasing in properties for un-used material is the same for the ex-used material. fig. 9 stress-strain curve at room temperature for un-used and ex-used stainless steel 321h. fig. 10. stress-strain curve at 300oc temperature for un-used and ex-used stainless steel 321h. fig. 11 stress-strain curve at 500oc temperature for un-used and ex-used stainless steel 321h. pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com ahmed naif al-khazraji al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 110 (2017) 8 fig. 12 stress-strain curve at 700oc temperature for un-used and ex-used stainless steel 321h. 5. acknowledgements the authors gratefully acknowledged midland refineries company-daura refinery (mrc) for providing the needed samples for experiments and for the support for this work. this research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. 6. references [1] api 530 (2004) calculation of heater tube thickness in petroleum refineries, fifth edition, american petroleum institute. [2] fernando vicente (2013) defining the optimal life management strategy for gas heater tubes., inspectioneering journal,vol. 19, issue 3. [3] takao endo; fujimitsu masuyama; and kyuseop park (2003) change in vickers hardness and substructure during creep of a mod.9cr– 1mo steel. materials transactions, vol. 44, no. 2, pp. 239 246. [4] david j. allen and simon t. fenton (2007) a hardness-based creep rupture model for new and service aged p91 steel. international conference on life management and maintenance for power plants (baltica vii), helsinki, pp.156–170. [5] shimpei fujibayashi; yuuji ishikawa; and yoshiaki arakawa (2006) hardness based creep life prediction for 2.25cr–1mo superheater tubes in a boiler. isij international, vol. 46, no. 2, pp. 325–334. [6] astm e23 (2002) standard test methods for notched bar impact testing of metallic materials. astm international. [7] yong jiang; jianming gong; zhongzheng zhang; ruisong zhu; and dongxing xi (2008) remaining life and fracture evaluation of incoloy800h furnace tubes serviced at high temperature for 100000 h. journal of pressure equipment and system 6, pp. 52-55. [8] josip brnic and marino brcic (2015) comparison of mechanical properties and resistance to creep of 20mncr5 steel and x10cralsi25 steel. procedia engineering 100, pp. 84 – 89. [9] v. moura; aline yae kina; sérgio souto; l. d. lima; and fernando b. mainier (2008) influence of stabilization heat treatments on microstructure, hardness and intergranular corrosion resistance of the aisi 321 stainless steel. journal of materials science, vol. 43, issue 2, pp. 536-540. [10] m. anderson; f. bridier; j. gholipour; m. jahazi; p. wanjara; p. bocher; and j. savoie (in revision from january 19 2016) mechanical and metallurgical evolution of stainless steel 321 in a multi-step forming process. journal of materials engineering and performance. [11] mehdi haj; hojjatollah mansouri; reza vafaei1; golam reza ebrahimi; and ali kanani1 (2013) hot compression deformation behavior of aisi 321 austenitic stainless steel. international journal of minerals, metallurgy and materials, vol. 20, no. 6, page 529. [12] j. g. gonzález-rodríguez; a. luna-ramírez; and a. martínez-villafañe (1999) effect of hot corrosion on the creep properties of types 321 and 347 stainless steels. journal of materials engineering and performance, vol. 8, issue 1, pp. 91-97. [13] k. kurihara; h. kokawa; s. sato; y. s. sato; h. t. fujii; and m. kawai (2011) grain boundary engineering of titanium-stabilized 321 austenitic stainless steel. journal of pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com ahmed naif al-khazraji al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 110 (2017) 9 materials science, vol. 46, issue 12 , pp. 4270-4275. [14] regina c. de sousa; jose c. c. filho; auro a. tanaka; ayana c. s. de oliveira; and wilman e. i. ferreira (2006) effects of solution heat treatment on grain growth and degree of sensitization of aisi 321 austenitic stainless steel. journal of materials science, vol. 41, issue 8 , pp. 2381-2386. [15] p. rozenak and d. eliezer (1989) behavior of sensitized aisi types 321 and 347 austenitic stainless steels in hydrogen. metallurgical transactions a, vol. 20a, pp. 2187-2190. [16] designation: a 312/a 312m (2010) standard specification for seamless, welded, and heavily cold worked austenitic stainless steel pipes. astm international. [17] iso 6507-1 (2005) metallic materials vickers hardness test, part 1: test method. international organization for standardization. [18] mattias calmunger (2011) effect of temperature on mechanical response of austenitic materials, linköping university, sweden. pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com )2017( 1-12، صفحة 2، العدد13دجلة الخوارزمي الھندسیة المجلماحمد نایف الخزرجي 10 تأثیر العمر التشغیلي لفترات زمنیة طویلة على الخصائص لسبیكة الفوالذ المقاوم للصدأ والتي تعمل بدرجات حرارة عالیة 321hاالوستنایتي من النوع **سمیر علي امین *احمد نایف الخزرجي ***حسام احمد الورمزیاري التكنولوجیةالجامعة /المیكانیكیةقسم الھندسة ***، **، * dr_ahmed53@yahoo.com : االلكتروني البرید* alrabiee2002@yahoo.com البرید االلكتروني: ** husamahmed75@yahoo.com : االلكتروني البرید*** الخالصة االختبارات المیكانیكیة، عن طریقخدمتھا یمكن الحصول علیھا أثناءفي التغیرات الحاصلة في الخصائص المیكانیكیة للمواد نتیجة للظروف المختلفة األفران أنابیببحیث یمكن االستعانة بالتغیرات الحاصلة للخصائص في تقدیر حالة ھذه المواد ودرجة الضرر المتولدة فیھا وكمثال للجانب التطبیقیة الفوالذ المقاوم للصدأ االوستنایتي ولندرة البحوث التي تستخدم سبیكة . عمریة تتجاوز العمر التصمیمي لھا لمدةرجات حراریة عالیة ودالحراریة التي تعمل ب 321h الصدمة باالعتماد على نتائج أثناءمتانة الشد، االستطالة، الصالدة، والطاقة الممتصة ھذه الخصائص مثل متانة الخضوع، فقد تم دراسة دراستھافي للحصول على فرن حراري عائد لوحدة ھدرجة النفثا في مصفى الدورة أنابیبنماذج من ھذه السبیكة مستخدمة في صناعة فقد تم تقطیع . االختبارات العملیة اختبار الشد لحالتي النماذج الجدیدة بزیادة درجة حرارة. المقارنة بین النتائج ألغراضنفسھا دراسة نماذج جدیدة من نوع السبیكة فضال عن، عینات اختباریة االختبار تصرف متماثل لمنحني نفسھا حرارة الدرجة بوظھرت عینات حالتي المعدن المستخدم ، وقد اوالمستخدمة سابقا اظھرت نقصان في متانة الشد صان في القدرة على االستطالة نتیجة التحمیل في حالة العینات ذات العمر قنمع زیادة في متانة الخضوع لحالة المعدن المستخدم سابقة، مع االنفعال االجھاد و %) ١١,٢٨(بمقدار الصالدة والطاقة الممتصة من قبل المعدن قبل حدوث الكسر وحصول زیادة في كل من التشغیلي الطویل عنھا في العینات الجدیدة، .یل مقارنتا مع العینات الجدیدةالة العینات ذات العمر التشغیلي الطوعلى التوالي لح%) ١٤( pdf created with pdffactory trial version www.pdffactory.com mailto:dr_ahmed53@yahoo.com mailto:alrabiee2002@yahoo.com mailto:husamahmed75@yahoo.com http://www.pdffactory.com http://www.pdffactory.com al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 7485 (2015) profiles and geotechnical properties for some basra soils abbas j. al-taie ministry of higher education and scientific research/ baghdad email: abbasjaltaie@yahoo.com (received 1 september 2014; accepted 4 january 2015) abstract basra province is known for its logistic location for trading activity and oil industry. by geological point of view, basra areas are believed to consist mainly of alternation of (clay, silty clay, clayey silt, silt and sand) type of soil. any development of industry in this area should be affected by the occurrence of the clay soil. that is why the investigation to the soil is more than necessary. in this case, a vast testing program was carried out by the author to evaluate the various formations constituting the of some basra soils. an attempt to characterize and discuss the nature, minerals, engineering behavior and field properties of soil samples extracted from more than one thousand and one hundred boring liner meters of three sites was performed. the average values of various geotechnical design properties are calculated and plotted with depth. a preview of climate, geology, seismicity and earthquakes of the study area was conducted. finally, the typical soil profiles were prepared. keywords: basra soil, soft clay, lean clay, atterberg limits, moisture content, shear strength, standard penetration, 1. introduction although basra province has logistic location for trading activity and oil industry, little attention has been given to geotechnical properties of the basra soil (hanzawa, 1977). based on laboratory and field tests carried out during the geotechnical investigation for three large water projects (site1, site2 and site3), characterization and discussion of the various formations constituting the soil of basra province were given. the selected samples extracted from more than 1100 boring liner meters used to achieve the required purposes. totally, 39 boreholes were drilled from natural ground and extended into a depth of 30 m. the number of boreholes for site1, site2 and site3 are 24, 9 and 6 boreholes respectively. many of the samples were obtained from site1 which located about 18 km to the north of al-zubair district. also, samples collected from site2 (located about 11 km south-east of al-zubair district) and site3. the boreholes in site3 are distributed along a line of 17 km length between al-zubair and abu alkhaseeb districts as shown in fig. 1. in addition to the field tests, a vast laboratory testing program was carried out. the natural water content, atterberg limits, sieve analysis and hydrometer, specific gravity, and consolidation test were included in this program. 2. description, climate, geology, seismicity and earthquakes of the study area 2.1. sites description and climate topographically, the sites are located within a flat plain called "mesopotamian plain" that slopes gently between baghdad and basra provinces and is also located between the rivers tigris and euphrates. this plain was historically lush but is now generally arid; palm trees and bushes densely cover narrow belts of natural levees rimming the euphrates and tigris rivers courses and artificially irrigated areas. the climate of mesopotamian is semi-arid with maximum temperature up to mailto:abbasjaltaie@yahoo.com abbas j. al-taie al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 7485 (2015) 75 +53°c in july-august and a minimum temperature of -7°c in january. average annual precipitation is 150 mm/year (mostly occurring from november to march) and can reach 250 mm/year and it falls to <100 mm/year towards the desert causing generally semi-desert to desert climatic conditions, aqrawi, 2001. fig. 1. sites location. 2.2. geology of the area lake/marsh complex in south iraq comprising the ancient tigris-euphrates-karun delta, and modern tidal flats and shatt al-arab/karun estuary/delta. most of the lower mesopotamian plain is flat broad area (sometimes below sealevel).the mesopotamian zone was represents by the quaternary sediments that range in age from pleistocene to holocene, and in thickness from few meters up to 250 m, which were deposited by the interacting tigris and euphrates rivers, on the alluvial fans from the surrounding elevated areas. the quarter]; nary sediments are composed mainly of alternation of clay, silty clay, clayey silt, silt, sand and gravel. plasticity of these soil sediments varied from low to high. these sediments often have a greyish tint due to increased contents of organic matter and traces of biological activity; also it is marked by the presence of well-preserved recent fossils (bivalves and gastropods), see fig. 2, (philip, 1969; kukal and sa'adalla, 1973; raji and salman, 1983). 2.3. structural geology according to the tectonic map of iraq (fig. 3), iraq can be divided into three tectonically different areas: the stable shelf with major buried arches and anti-forms but no surface anticlines, the unstable shelf with surface anticlines and zagros suture which comprises thrust sheets of radiolarian chert, igneous and metamorphic rocks. the investigated sites in this paper are located within the zubair subzone in the south of mesopotamian zone at the stable shelf area. the zubair subzone is bounded in the north by the takhadid-qurna transversal fault. the southern boundary of the subzone is either located at the al batin fault or long a transversal fault in kuwait. the northern dome of the zubair anticline is associated with a negative gravity anomaly. however the southern dome of this anticline and the structures to the south in kuwait are not. these structures and the southern zubair dome could be included in another subzone. this subzone forms the southernmost unit the mesopotamian zone and has a uniform structural style controlled by the underlying basement. it contains prominent n-s trending structures which continue hundreds of kilometer southwards into kuwait and eastwards saudi arabia, jassim and goff, 2006. fig. 2. geological map of iraq (jassim & goff, 2006) abbas j. al-taie al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 7485 (2015) 76 fig. 3. tectonic map of iraq (after jassim & goff, 2006). 2.4. seismicity and earthquakes the seismicity of iraq is of intermediate character and the focal depth is shallow. the seismicity of the stable shelf is due to located deformation but the seismicity of folded area is due to forces resulting from the movements of the arabian plate towards the north and north east. according to the seismic zoning map, (isointensity map, fig. 4), the investigated sites lie within the no damage zone (zone iii). although iraq is seemingly secure from seismic hazards, seismic observations indicate otherwise. earthquakes are likely to happen and may cause substantial damage, especially in north east of iraq and in the mesopotamian plain due to liquefaction of quaternary sediments. it is therefore important to take into consideration seismic parameters in future design of large building, jassim and goff, 2006. fig. 4. isointensity map of iraq (after (jassim & goff, 2006). 3. results and discussion of basic and engineering properties 3.1. moisture content, specific gravity and unit weight the distribution of moisture content and (total and dry) unit weight with depth for all sites is shown in fig. 5, and average values of all the data points are summarized in table 1. overall, moisture content, specific gravity and unit weight values are uniform with depth. a detailed assessment of the data reveals that average moisture content in the site3 is somewhat larger than for the other sites, with a corresponding slightly smaller unit weight. the site1 has the lowest moisture content and highest unit weight. values for the site2 and the site3 are very similar. the average specific gravity of basra soil is typically 2.735. however, there is no clear difference in the results from the various formations. 3.2. atterberg limits of basra soil atterberg limits tests were conducted on 115 samples of soil fractions passing sieve no. 40 according to astm d 4318. the variation of values of liquid limit (l.l), plastic limit (p.l), and plasticity index (p.i) with different depth is summarized in fig. 6 and the average values listed in table 1. except for the presence of some sandy lenses in the site 1, the values are remarkably uniform, and 88% of data for all three sites fall in the classification „clay of low plasticity‟ while 12% of data indicates high plasticity on the plasticity chart. reexamination of the data in table 1 confirms that the average values of index properties for all sites are very similar. the soil in site 2 appears to have a slightly higher average plastic limit with a correspondingly lower average plasticity index than the other sites. overall, natural moisture content values fall close to the liquid limit. fig. 6 shows the distribution of pl/ll ratio of basra soil with depth. this ratio varies from 0.76 to 0.37 with an average value of 0.56. from the scattering of experimental points of basra soil shown in fig. 6, it is reasonable to consider that pl/ll ratio remains same. sridharan et. al. 2004, brought out that pl/ll ratio depends upon the type of clay minerals or mixtures of clay minerals and associated cations and its concentrations. for any particular region, the pl/ll ratio varies marginally or remains same. abbas j. al-taie al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 7485 (2015) 77 thus soils from the same region can be expected to have same ratios of pl/ll since they possibly have same type of clay mineral mixtures and same type of exchangeable ions and ion concentration. accordingly, one can expected that the soil from all investigated sites in basra may have same type of clay mineral mixtures and same type of exchangeable ions and ion concentration. this finding is compatible with section 3.4 of this paper. an approximate determination of the shrinkage limit (sl) of basra soil was performed in this paper using casagrande method, das 2010. by using the a-line and the u-line on plasticity chart, the plasticity index and liquid limit of basra soil with different depths used to determine sl and the results are shown in fig. 6. it can be seen that sl values range from 10 to 23 with an average value of 17. the typical values of sl for different clay minerals indicate that sl of illite ranges from 15 to 17. kaolinite has sl values varies from 25 to 29, mitchell, 1976. to identify the state of basra soil in the field, liquidity index was calculated and the results are shown in fig. 6. on average, 44% of liquidity index values range from 0.5 and 0.94. according to terzighi et. al. 1996, the expected unconfined compressive strength of this soil ranges between (30 and 100) kpa. table 1, values of the physical properties of basra soil. site1 site2 site3 maximum minimum average maximum minimum average maximum minimum average gs 2.92 2.52 2.73 2.81 2.68 2.74 2.78 2.50 2.74 mc, % 49.4 10.0 30.2 40.8 26.4 34.2 44.8 27.4 35.9 t, kn/m 3 23.78 15.33 19.48 23.06 17.71 20.29 21.87 17.70 19.35 d kn/m 3 22.00 11.05 15.10 17.78 12.58 15.21 17.17 12.72 14.25 ll, % 59 21 40 46 34 40 49 31 40 pl, % 32 14 22 28 22 24 25 21 23 pi, % 31 5 19 23 11 16 26 10 17 clay,% 79 3 48 70 38 63 71 49 63 silt,% 49 4 32 42 19 34 44 15 32 sand,% 89 0 19 43 1 3 66 1 8 gravel, 0 0 0 0 0 0 0 0 0 fig. 5. variation of moisture content, specific gravity and bulk unit weight of basra soil. abbas j. al-taie al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 7485 (2015) 78 fig. 6. atterberg limits and liquidity index of basra soil fig. 7. particle size percentages of basra soil. the liquidity index of 30% of the investigated soil is less than 0.5 and greater than zero, while 26% of liquidity index values are less than or equal to zero. when the liquidity index is near zero, the expected compressive strength generally lies between (100 and 500) kpa, terzighi, 1996. 3.3. particle size percentage and texture of basra soil grain size analysis tests were performed according to astm d 422. the percentages of gravel, sand, silt and clay particles of 126 soil samples are plotted against depth in fig. 7. note that basra soil is predominantly silt and clay with trace of sand and no gravel. in general, the quantities of the various constituents in sites 2 and 3 are relatively constant with depth. based on the average values quoted in table 1, it can be seen that there is some tendency for the quantity of sand in site 1 to increase with depth. however, the average data reveals that sand content in the site1 is greater than for the other sites, with corresponding smaller clay content. the site2 has the lowest sand content and highest silt content. it can be seen that the average values for sites 2 and 3 remain almost the same. fig. 8. textural soil classification (tsc). the unified soil classification system (uscs) and textural soil classification (tsc) were used to classify the soil of basra. it was found that the soil is lean clay (cl) according to (uscs) and clay to silty clay according to (tsc), see figs. (8 and 9). 0 20 40 60 atterberg limits, (%) 40 35 30 25 20 15 10 5 0 d ep th ,( m ) averge of ll averge of pl averge of pi 8 16 24 32 shrinkage limit, (%) 30 25 20 15 10 5 0 d ep th ,( m ) line of average 0 0.4 0.8 1.2 pl/ll 30 25 20 15 10 5 0 d ep th ,( m ) site 1 site 2 site 3 -0.6 -0.3 0 0.3 0.6 0.9 1.2 li 30 25 20 15 10 5 0 d ep th ,( m ) site 1 site 2 site 3 line of average abbas j. al-taie al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 7485 (2015) 79 3.4. mineralogy of basra soil the identification of clay minerals is of the most important since they greatly influence the engineering behavior and properties of the soil, day, 2006. the amount of attracted water, which is influenced by clay minerals, effects on the plasticity of a clay soil which is influenced by the amount of its clay fraction and the type of clay minerals present, kempfert and gebreselassie, 2006. one of a more common approach to identify clay minerals present in a soil is to use the location of clay particles as they plot on the plasticity chart (fig. 9). it should be keep in mind that the estimation of clay minerals by this method is approximate because soil can contain more than one type of clay mineral, day, 2006; eden and crawford, 1957. fig. 9. plasticity characteristics of common clay minerals. table 2, the average values of the consolidation parameters of basra soil. site1 site2 site3 maximum minimum average maximum minimum average maximum minimum average eo 1.390 0.412 0.856 1.187 0.6586 0.934 1.131 0.685 0.977 cc 0.43 0.10 0.198 0.36 0.17 0.245 0.43 0.18 0.292 cs 0.056 0.010 0.027 0.057 0.012 0.030 0.038 0.020 0.030 cr 0.18 0.04 0.10 0.18 0.10 0.13 0.25 0.11 0.15 rr 0.027 0.003 0.014 0.028 0.006 0.015 0.018 0.010 0.015 examination of fig. 9 indicates that the soil of basra is composed mainly of illite with a tendency toward kaolinite. very small amounts of montmorillonite can be seen in fig. 9. as primary conclusion, basra soil is mainly composed of illite with kaolinite as clay minerals. this result has much significance but final conclusion can be drawn by x-ray diffraction to identify the actual clay minerals. therefore further work on the compositional analysis of the basra soil is planned. illite is the most common clay mineral in stiff clays and shales as well as in postglacial marine and lacustrine soft clay and silt deposit, while kaolinite is one of the most common clay minerals in sedimentary and residual soils, terzaghi et. al. 1996. most soft clay deposits of marine and lacustrine origin are composed of a mixture of minerals that are likely to include illite and chlorite, substantial amounts of quartz and feldspar, and some montmorillonite, micas, and carbonates. 3.5. compressibility of basra soil a series of consolidation tests (119 tests) were carried out on selected specimens, as a part of this study, to determine their compressibility characteristics. the results used to calculate the consolidation parameters of basra soil. fig. 10 shows the variations of compression and swelling indices (cc and cs), and compression and recompression ratios (cr=(cc/(1+eo) and rr=cs/(1+eo)) with depth below the ground surface. as can be readily seen from this figure, values of (cc, cs, cr and rr) vary widely for a given depth below ground. the average values of these parameters vary with a narrow range for depth up to 15 m, and then values decrease slightly with depth. the average values listed in table 2 suggest that basra soil has a compression index, cc, in the range of 0.10 and 0.43 with an average value of 0.22. this range is more or less identical to that suggested by holtz and kovacs 1981 for chicago silty clay, cl, where cc ranged from 0.15 to 0.30. furthermore, about 36% of cc calculated in the present work is less than 0.20, abbas j. al-taie al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 7485 (2015) 80 while 65% of the values ranges from 0.20 to 0.40. therefore, the degree of compressibility of basra soil, according to kulhawy and mayne 1990, can be classified as intermediate. regarding to cs of basra soil, it ranges from 0.010 to 0.056 with an average value of 0.029. typical values of cs given in literatures are ranged from 0.015 to 0.035, where the lower values are for clays of lower plasticity and low ocr, leonards 1976. values of cs outside the range of 0.005 to 0.05 should be considered questionable as stated by holtz and kovacs 1981. fig. 10. consolidation parameters of basra soil. the ratio of cs/cc for basra soil varies from 0.043 to 0.377 (fig. 10) with an average value of 0.12. terzaghi et. al., 1996, demonstrated that most values of cs/cc are in the range of 0.02 to 0.20. kempfert and gebreselassie 2006, mentioned that cs/cc is a constant value and varies between 0.2 and 0.4. for the lacustrine soft clays in southern germany, scherzinger 1991, found that cs/cc is on average 0.2. according to das 2008, the range of cs /cc is approximately from 0.1 to 0.2. nevertheless, very low values of cs/cc, even lower than 0.02, correspond to highly structured and bonded soft clay and silt deposits, while high values correspond to micaceous silts and fissured stiff clays and shales, terzaghi et. al.,1996. 3.6. swelling potential of basra soil in this paper, an evaluation for swelling potential of basra soil was carried out based on the average values of atterberg limits and percent of clay fraction (<0.002mm). the classification system developed by abduljauwad and alsulaimani 1993, is adopted to achieve the above mentioned purpose as shown in fig. 11. an examination to fig. 11 reveals that the swelling potential of more than 70% of basra soil can be classified as low, while less than (30%) of this soil may undergo medium swell under saturation condition. the values of activity presented in fig. 11 reveal that basra soil is inactive and this soil has an activity less than 0.75. this result, however, is expected for basra soil which consists mainly of illite with kaolinite as clay minerals. illite has an activity of 0.5 to 1.0, while the activity of kaolinite is 0.5, das, 2011. fig. 11. swelling potential of basra soil. 3.7. direct shear test of basra soil a series of direct shear test have been carried out on selected soil samples at different depths of each borehole. totally, 120 tests were conducted according to astm d 3080 – 98. all tested soil samples were carried out under soaking during the 0 10 20 30 40 50 60 70 particles finer than 0.002mm,(%) 0 10 20 30 40 50 60 70 p i , (% ) low very high high medium 0 0.1 0.2 0.3 0.4 cs/cc 30 25 20 15 10 5 0 d e p th , (m ) line of average abbas j. al-taie al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 7485 (2015) 81 test. the variation of shear strength parameters (i.e cohesion (c) and angle of internal friction (ф)), with depth is shown in fig. 12 and summarized in table 3. an increasing in values of internal friction with depth can be seen at site 1. this is mainly due to increasing coarse grains (sand content) as shown in fig. 7. except some values in site 1, low cohesion values appear for soil samples with depth. however, the average shear strength parameters values in sites 2 and 3 remain almost the same. these exhibit low shear strength parameters values which may be attributed to particle size of the soil at which the clay with water content closes to liquid limit than to plastic limit is predominated. fig. 12. variation of direct shear test results of basra soil table 3, shear strength and n-values of basra soil. values sites c,kpa ϕ n n60 maximum site1 150 43 >50 >50 minimum 0 0 2 2 average 36 19 30 30 maximum site1 60 8 29 16 minimum 13 0 5 3 average 24 4 10 7 maximum site1 55 9 28 16 minimum 2 0 5 3 average 23 5 10 7 3.8. standard penetration the standard penetration test is performed routinely in ground investigations in iraq. five hundred and fifty seven tests were conducted at different depths to achieve the purpose of this study. the n values were corrected (n60) and presented in as shown in figs. 13 to 15 and summarized in table 3. the observed scatter in the data is considerable. except site 1, the values are remarkably uniform, and data fall in the classification „soft to stiff‟ of the consistency of cohesive soil. the n values for the site 1 are often considerably higher. the reasons for this may be attributed formation of soil in site 1 which seems to have higher sand content than that encountered elsewhere. fig. 13. standard penetration test results for site 1. fig. 14. standard penetration test results for site 2. 3.9. typical profiles and ground water table of basra soil in this paper, with reference to boring results, typical soil profiles were prepared and showed mainly cohesive soil grading into clay and silt 0 10 20 30 40 50 n60 30 25 20 15 10 5 0 d e p th , (m ) site 2 0 10 20 30 40 50 n 30 25 20 15 10 5 0 d e p th , (m ) site 2 0 10 20 30 40 50 n60 30 25 20 15 10 5 0 d e p th , (m ) site 1 0 10 20 30 40 50 n 30 25 20 15 10 5 0 d e p th , (m ) site 10 9 18 27 36 45 f, (degree) 30 25 20 15 10 5 0 d e p th , (m ) site 1 site 2 site 3 line of average 0 30 60 90 120 150 c, (kpa) 30 25 20 15 10 5 0 d e p th , (m ) site 1 site 2 site 3 line of average abbas j. al-taie al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 7485 (2015) 82 (fig. 13). the upper part of the soil is often medium stiff to stiff clay to depths of (2.5 to 4.5) m or more, but the deeper soil is identified by clay with soft consistency to depths of (12.0 to 18.0) m or more. below this depth, and down to a depth of 30m, the soil is practically stiffer with the present of cohesionless layers of silty sand. fig. 15. standard penetration test results for site 3. basra soil usually show non pronounced stratification and sometimes organic matter, shell and well-preserved recent fossils (bivalves and gastropods) are present in this deposits as shown in figs. 16 to 18. also, it is marked by the presence of lenses of clay and sand. this soil has a color of brown to grayish brown, gray to dark gray and brownish gray. jassim and goff 2006, attributed the grayish tint of this soil to the increasing the content of organic matter and traces of biological activity. fig. 16. typical profiles for site 1. basra soil usually show non pronounced stratification and sometimes organic matter, shell and well-preserved recent fossils (bivalves and gastropods) are present in this deposits as shown in fig. 19. also, it is marked by the presence of lenses of clay and sand. this soil has a color of brown to grayish brown, gray to dark gray and brownish gray. jassim and goff 2006, attributed the grayish tint of this soil to the increasing the content of organic matter and traces of biological activity. the underground water table in basra was encountered at depths varied from (0.55 to 3.0)m below the natural ground level. fig. 17. typical profiles for site 2. fig. 18. typical profiles for site 3. fig. 19. shell and well-preserved recent fossils (bivalves and gastropods). 30 20 10 0 d e p th , m site 2 fill soil sand medium stiff clay soft clay stiff clay 30 20 10 0 d e p th , m site 3 fill soil medium stiff to stiff clay sand soft clay medium stiff clay lenses of clay and sand 0 10 20 30 40 50 n60 30 25 20 15 10 5 0 d e p th , (m ) site 3 0 10 20 30 40 50 n 30 25 20 15 10 5 0 d e p th , (m ) site 3 abbas j. al-taie al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 7485 (2015) 83 4. conclusion a vast laboratory and field testing program was carried out to characterize and discuss the various formations constituting the soil of basra province. a preview of climate, geology, seismicity and earthquakes of the study area was conducted. accordingly, the following conclusions are obtained: 1. topographically, the investigated sites are located within a flat plain called mesopotamian plain with semi-arid climate. 2. geologically, the quaternary sediments that range in age from pleistocene to holocene, and in thickness from few meters up to 250 m, which were deposited by the interacting tigris and euphrates rivers, that represent the investigated sites. 3. according to the tectonic map of iraq, the investigated sites are located within the zubair subzone in the south of mesopotamian zone at the stable shelf area. 4. according to the seismic zoning map, the investigated sites lie within the no damage zone. although iraq is seemingly secure from seismic hazards, seismic observations indicate otherwise. earthquakes are likely to happen and may cause substantial damage; therefore important to take into consideration seismic parameters in future design of large building. 5. basra soil composes mainly of alternation of clay, silty clay, clayey silt, silt and sand. the predominated plasticity of this soil is low. this soil often has a greyish tint and marked by the presence of well-preserved recent fossils (bivalves and gastropods 6. mineralogy, basra soil composes mainly of illite with a tendency toward kaolinite with very small amounts of montmorillonite. 7. the degree of compressibility of basra soil classified as intermediate. the ratio of cs/cc for this soil varies from 0.043 to 0.377 with an average value of 0.12, while the cs ranges from 0.010 to 0.056 with an average value of 0.029. 8. the swelling potential of basra soil classified as low with a tendency toward medium, this soil is inactive and has an activity less than 0.75. 9. according to liquidity index values, the expected unconfined compressive strength of about 50% this soil ranges from (30 to 100) kpa. 10. in general, basra soil is predominantly silt and clay with trace of sand and no gravel, thus, it's classified as lean clay. the water content of tis soil closes to liquid limit leading to intermediate compressibility, low shear strength and hence low bearing capacity notation c cohesion cc compression index cr compression ratio cs swelling index eo initial void ratio gs specific gravity li liquidity index ll liquid limit mc natural moisture content n number of b ows in spt n60 corrected n value for field condition pi plasticity index pl plastic limit rr recompression ratios sl shrinkage limit spt standard penetration test greek letters ϕ angle of internal friction d total unit weight t dry unit weight 5. references [1] abduljauwad, s. n., and al sulaimani, g. j., 1993, “determination of swelling potential of al qatif clay”, geotechnical testing j., asce, vol.16, no.4, pp 469-484. [2] aqrawi, a. a. m., 2001, "stratigraphic signatures of climatic change during the holocene evolution of the tigris-euphrates delta, lower mesopotamia”, in fard, a. m., (editor of special issue), “recognition of abrupt climate changes in elastic sedimentary environments, in cloetingh et. al. (editors), global and planetary change, 25:pp.267283. das, b. m., 2008, "advanced soil mechanics' 3rd edition, taylor & francis, new york, ny 10016, usa. [3] day, r. w., 2006,"foundation engineering handbook: design and construction with the abbas j. al-taie al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 7485 (2015) 84 2006 international building code", mcgrawhill companies, inc. [4] eden, w. j., and crawford, c. b., 1957, "geotechnical properties of leda clay in the ottawa area", soil mechanics section, division of building research, ottawa, canada. [5] hanzawa, h. (1977b) “geotechnical properties of normally consolidated fao clay.” soils and foundations, 17(4), 1−15. [6] holtz, r. d., and kovacs, w. d., 1981, "an introduction to geotechnical engineering", prentice hall inc., new jersey.pp341. [7] jassim, s. z. and goff, j. c., 2006, "geology of iraq", dolin, prague and morravian museum, brno. [8] kempfert, h. g., and gebreselassie, b., 2006, "excavations and foundations in soft soils", springer-verlag berlin heidelberg. [9] kukal, z., and sa'adalla, a., 1973, "aeolian admixtures in the sediments of the north persian gulf". in: b. h. purser (ed.), the persian gulf, springer-verlag, berlin, pp. 115-121. [10] kulhawy, f. h., and mayne, p. w., 1990, "manuel on estimating soil properties for foundation design",. electric power research institute, epri. [11] leonards, g. a., 1976, "estimating consolidation settlements of of shallow foundations on overconsolidated clays", special report 163, transportation research board, pp 13-16. [12] mitchell, j. k., 1976. “fundamentals of soil behavior”, wiley, new york [13] philip, g., 1969, "mineralogy of recent sediments and some detrital deposits". bull. col. sci., baghdad university; 9, baghdad. [14] raji, w., and salman, b., 1983, "palaeontological and environmental study of the mesopotamian plain in samawanasirriya area", survey of iraq, baghdad, unpublished report. [15] scherzinger, t., 1991, "material verhalten von seetonen-ergebnisse von laboruntersuchungen und ihrebedeutungfür das bauen in weichembaugrund", p.hd. thesis, institutfürbodenmechanik und felsmechanik der universittfridericiana in karlsruhe, heft 122. [16] sridharan, a., rao, p. r. and miura, n., 2004. “characterisation of ariake and other marine clays”, international symposium on lowland technology islt 2004, bangkok. pp. 53-58. [17] terzaghi, k., peck, r. b., and mesri, g. 1996, "soil mechanics in engineering practice", john wiley & sons, inc., 3rd. edition, new york. (2015)7485 ، صفحت 2، العذد11دالهنذسيت المجل الخىارزميجلة م عباس جىاد الطائي 85 البصرة لبعض تربوالخصائص الجيىتقنيت المقاطع عباس جىاد الطائي تغذاد/ وصاسج انتؼهٍى انهؼانً وانثحث انؼهًً abbasjaltaie@yahoo.com :انثشٌذ االنكتشوًَ الصتخال تثادل االَىاع خهح َظش خٍىنىخٍح، ٌؼتمذ أٌ يُاطك انثصشج تتأنف أساسا يٍ ويٍ . وصُاػح انُفظ انتداسيَشاط نميىلغ نىخستً بيحافظح انثصشج تًتاص انتشتح تىخىدٌدة أٌ تتأثش اٌ اي ػًهٍح تطىٌش نهصُاػح ضًٍ هزِ انًُطمح (. لوانشو وانغشٌٍانطًٍُ، وانغشٌٍانطٍٍ انغشًٌُ، وانطٍٍ، ) االتٍح يٍ انتشتح نتمىٌى ي وحمهً واسغ ، تى تُفٍز تشَايح يختثشانذساسحفً هزِ . ونهزا انسثة فاٌ اخشاء تحشٌاخ يىلؼٍح نهتشتح ضًٍ هزِ انًُطمح ضشوسي خذا. انطٍٍُح انهُذسً انسهىنفضال ػٍ ، انًكىَح نها وانًؼادٌ انتشتح تى إخشاء يحاونح نتىصٍف ويُالشح طثٍؼحفمذ . انتكىٌُاخ انًختهفح انتً تشكم تشتح انثصشج انمٍى نًختهف تى حساب يتىسظ . يٍ ثالثح يىالغ فً يحافظح انثصشجاخزخ انًستخشخح يٍ أكثش يٍ أنف ويائح يتشوانخصائص انحمهٍح نًُارج انتشتح وأخٍشا، . صنضانٍح وانضالصل نًُطمح انذساسحنًُاخ واندٍىنىخٍا والاكًا تى استؼشاض . يغ انؼًك وتى سسًهاأػًاق يختهفح وػهىخصائص انتصًٍى اندٍىتمٍُح .لاتهٍح االَتفاخ نتشتح انثصشج كًا تى اػذاد يماطغ تًىرخٍح نتسهسم طثماخ انتشتح فٍها تمىٌىتى mailto:abbasjaltaie@yahoo.com al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 3344 (2014) experimental study of the effect of exhaust gas recirculation (egr) and injection timing on emitted emissions at idle period miqdam tariq chaichan department of machines and equipments engineering/ university of technology e. mail: miqdam_tc@uotechnology.edu.iq (received 26 june 2014; accepted 22 october 2014) abstract heavy-duty diesel vehicle idling consumes fossil fuel and reduces atmospheric quality at idle period, but its restriction cannot simply be proscribed. a comprehensive tailpipe emissions database to describe idling impacts is not yet available. this paper presents a substantial data set that incorporates results from di multi-cylinders fiat diesel engine. idle emissions of co, hydrocarbon (hc), oxides of nitrogen (nox), smoke opacity, carbon dioxide (co2) and noise have been reported, when three egr ratios (10, 20 and 30%) were added to suction manifold. co2 concentrations increased with increasing idle time and engine idle speed, but it didn’t show clear effect for it advancing. co concentrations increased for all the studied tests with adding egr. hc concentration increased with idle time advance, but it reduced with increasing idle speed and advancing engine it. nox concentrations reduced with adding egr for all the tested variables. nox increased with increasing idle time, engine speed and advancing it. smoke opacity increased with increasing idle time and retarding it. using egr increased opacity for all tested cases. egr addition reduced engine noise for all tested cases. engine noise increased with increasing idle time and retarding it. keywords: engine idling, idle time, injection timing, egr, nox, pm, hc co, noise, smoke opacity. 1. introduction today the diesel engine is the power source with the lowest specific fuel consumption and is essential in the global reduction of carbon dioxide emissions. the success of the diesel engine is due to a precisely controlled combustion process and high technology exhaust after treatment. this combination yields very low fuel consumption combined with the lowest possible emissions. but diesel engines still have some problems especially in cold start, warm-up and idle regions [1 & 2]. in iraq, diesel engines are used very highly as long-haul trucks, buses, mini buses, trains, constructing machines and electrical generators. most of these engines typically spend a substantial percentage of time idling while the driver takes mandatory rest periods (i.e., hours of driving and rest, at control and checking points or at traffics). that amount of time varies considerably. drivers may allow their engines to idle for a variety of reasons and under many different circumstances. lutsey [3] found climate control to be the most common reason cited by drivers for idling, and use of accessories and concerns about start-up were also cited. on-duty drivers of both longand short-haul trucks may also tend to idle their engines during the workday while waiting to load or unload or while sitting in traffic, or they may idle their engines for other reasons related to their work or to vehicle operation and maintenance [4 & 5]. drivers of long-haul trucks often live in these trucks for days, sometimes weeks, at a time as they deliver these goods. when stopped overnight, many of these drivers leave their engines idling to heat or air-condition their cabs and produce power for the amenities they need to carry on their lives while on the road [6 & 7]. mailto:miqdam_tc@uotechnology.edu.iq miqdam tariq chaichan al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 3344 (2014) 34 diesel engine idling increases fuel consumption, engine wear, and required engine maintenance. the fuel consumption for diesel trucks at idle is typically 0.8–1.5 g/hr, depending on the engine size, ambient temperature, and load for hvac and other electrical loads. idling also causes undesirable emissions. the average emissions for heavy-duty diesel engines are shown in table 1. table 1, heavy duty diesel engine emissions at idle (g/hr) [8]. emission heavy duty diesel voltaic organic compounds (voc) 12.6 carbon monoxide (co) 94.6 oxides of nitrogen (nox) 144* particulate matters (pm) 2.57 carbon dioxide (co2) 8.224* source: environmental protection agency (epa) web site: www.epa.gov./oms/consumer/f98014.htm (april 1998) and *http://www.epa.gov/otaq/retrofit/decuments/r02025.p df (october 2002). heavy-duty trucks are typically parked and idled so the driver can rest at truck stops and roadside rest areas instead of checking into a motel. these stops can have hundreds of trucks idling in the parking area at once. diesel-powered trucks at idle produce noise, vibrations, and emissions that affect drivers, other truck stop or rest area patrons, and neighbors [9 & 10]. long duration idling consumes over one billion gallons of fuel annually in the united states, at a cost of over $2.5 billion [11]. idling of trucks, alone, is estimated to emit 11 million tons of co2, 180,000 tons of nitrogen oxides (nox), and 5,000 tons of fine pm each year. a single hour of truck engine idling consumes approximately one gallon of fuel and emits approximately 20 pounds of co2 [12]. warming up or cooling down a vehicle is the most common reason given for idling‚ in the winter and summer. a study of diesel school buses waiting in the wintertime found that restart and immediate departure produced fewer air pollutants compared to idling [13]. the usepa measured pm, nox, co, and pah from buses under idle and restart conditions and found that for periods longer than three minutes, more pollution was created by idling than by turning buses off and restarting them. in all cases they identify turning off the engine and restarting with immediate departure as a preferred approach [14]. the risks from elevated pollution due to idling extend to passengers as well as to people outside the vehicles. research shows that school buses self-pollute, meaning that emissions from the bus enter directly into the passenger compartment, even when the windows are closed. these pollutants concentrate more during idling [15 & 16]. opening the door of the bus after time spent idling, as is often done when buses are waiting to pick up children, can cause a spike in pm concentrations inside the bus [17]. the present investigations aims to measure the effect of idle time accompanied with using egr and variable injection timings on di multicylinders diesel engine emitted emissions at idle period. 2. experimental setup all experiments were performed with four cylinders di fiat engine. the engine was mounted on a test-bed and connected to a hydraulic dynamometer. power is supplied to the engine control unit, low pressure fuel pump and glow plug by a 12v automotive battery. in this study, the idle rpm was chosen at 1000 rpm to mimic the field observations. the 30-minute continuous idling period was chosen as a compromise emitted emissions. fig. 1 represents the rig used in recent study. table 2 illustrates the used engine specifications. the experimental study is foxed on investigating the effect of tested egr rates and different injection strategies on engine emitted emissions. fig. 2 shows the prodit heat exchanger used as egr unit. different combinations are assessed to study the effect of pilot injection strategy on idling period. two retarded injection timing (15 & 12 o btdc), and two advanced injection timing (20 & 23 o btdc) were used to study the effect of injection timing on engine idle at constant speed 1000 rpm. the results were compared with optimum injection timing (17 o btdc). the effect of variable engine idle speeds (600, 800, 1000 and 1100) were studied at constant it (17°btdc). http://www.epa.gov./oms/consumer/f98014.htm miqdam tariq chaichan al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 3344 (2014) 35 table 2, the tested engine specifications. fig. 1. photographic picture for the experimental rig. exhaust gas (smoke) opacity was measured continuously with the avl 439 partial flow opacimeter, which is particularly suitable for dynamic testing measurements with a response time less than 0.1 s and an accuracy of 0.1 per cent opacity. co with a non-dispersive infrared (ndir) analyzer and hcs with a flame-ionization detector (fid) were measured. nox was measured using a chemiluminescence analyzer. table 3 represents the equipment, detection principle and accuracy of measuring devices. all analyzers were calibrated at science and technology ministry of iraq. finally, combustion noise was measured with an avl 450 combustion noise meter. fig. 2. egr assembly used in the present study. 2.1. experimental procedure the experimental schedule included operating engine at different injection timing. four injection timings and three egr were studied. it must be highlighted that a preconditioning procedure was followed before most of the tests, in order to remove the deposited particulate matter on the exhaust pipe walls, which could be blown out and released during the following experimental trials. this procedure was followed before the idle operation and the fully warmed-up tests. 2.2. properties of tested fuel the conventional diesel fuel used was supplied by the al-doura refineries – baghdad, iraq and represents the typical, high sulfur (1% by weight) diesel fuel. the fuel properties are given in table 4. engine type 4cyl., 4-stroke engine model td 313 diesel engine rig combustion type di, water cooled, natural aspirated displacement 3.666 l valve per cylinder two bore 100 mm stroke 110 mm compression ratio 17:1 fuel injection pump unit pump 26 mm diameter plunger fuel injection nozzle hole nozzle: 10 nozzle holes nozzle hole dia.= (0.48mm) spray angle= 160 o nozzle opening pressure= 40 mpa miqdam tariq chaichan al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 3344 (2014) 36 table 3, summary of equipment, detection principle and accuracy of measurements. measuring item detection principle equipment (maker) scale range accuracy co ndir (non dispersive infrared) multigas mode 4880 0-10% vol. 0.01% co2 ndir (non dispersive infrared) multigas mode 4880 0-25% vol. 0.01% hc fid (flame ionization detector) multigas mode 4880 0-1000 ppm 0.01% nox cld (chemical luminescence detector) multigas mode 4880 0-1000 ppm 0.02% overall sound pressure precision sound level meter 4615 italy made 0-200 db 0.76% smoke opacity partial flow opacimeter avl 439 0-20 % vol. 0.24% table 4, diesel fuel used in recent study properties. 2.3. engine speed stability the idle stability depends strongly on the combustion process. misfires have a negative effect on the idle stability. during idle application from 600 to 1000 rpm engine speed stability was detected and ensured throughout the whole test. 3. results and discussions idle emissions from di multi cylinder fiat engine was considered in this study. the tests were conducted to measure the engine exhaust emissions to prepare acceptable data for what happening at idle period. many variables were tested as the following: 3.1. idling time effect fig.3 shows the effect of idling time on co2 concentrations when the engine runs at optimum injection timing (oit) and 1000 rpm. idling time=30 minute was chosen to clarify idle time effect, because this period occurrence is possible in traffics; like stopping in traffic light or in congestion, or as happens in iraq stopping in control points for frisking. co2 increase with increasing idling time to 10-15 min, after that it reduced with increasing time. increasing co2 concentrations means better combustion, while its reduction means poor combustion. co2 concentration reduced with increasing egr rates. fig. 3. idling time effect on co2 concentrations for variable egr rates at oit and 1000 rpm. egr addition will be on air account and will create poor and very rich zones. these zones increase co and hc concentrations on co2 account. the reduction in co2 concentration was 1.4, 3.58 and 7.1% for egr=10, 20 and 30 respectively compared with egr rate = 0%. 5.4 5.6 5.8 6 6.2 6.4 6.6 0 10 20 30 40 c o 2 c o n c e n tr a ti o n ( % v o l. ) idling time (min.) 17°btdc, 1000 rpm egr=0% egr=10% egr=20% egr=30% specification diesel chemical formula c10.8h18.7 mole weight (g) 148.3 density (g/cm 3 at 20 o c) 0.84 boiling point ( o c) 180-330 heat of evaporation (kj/kg) 280 lower heat value (mj/kg) 42.5 liquid viscosity (cp at 20 o c) 3.03 surface tension (mn/m at 20 o c) 34.1 flash point ( o c) 78 stoichiometric air fuel ratio 14.4 cetane number 45 auto-ignition ( o c) 235 carbon content (wt%) 87.4 oxygen content (wt%) 0 miqdam tariq chaichan al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 3344 (2014) 37 fig. 4. idling time effect on co concentrations for variable egr rates at oit and 1000 rpm. co emissions are generally low during idling and reduced further with advancing idle time from 0 to 15-20 min, after that it started to increase as fig. 4 represents. co reductions confirm the previous results that there is a combustion improvement during this period, due to engine heat improvements. fig. 5. idling time effect on hc concentrations for variable egr rates at oit and 1000 rpm. fig. 6. idling time effect on nox concentrations for variable egr rates at oit and 1000 rpm. co concentrations increased due to combustion deterioration, since continue heating will cause co2 to dissociate to co. adding egr increases co concentration for all rates districting its negative effect on this emission. the increments in co concentration with egr addition were 4.33, 27.67 & 53.57% for egr rates= 10, 20 & 30 respectively compared with adding 0% egr. since diesel engines generally have excess oxygen and high combustion temperatures, co emissions are generally much lower than co2 emissions. a significant amount of hc emissions are developed during the cold start of a diesel engine. a cold start is significantly below normal operating temperature. hc emissions occur mainly from poor fuel vaporization, which occurs during cold start. for the engine idle tests, data was acquired after the engine is wormed up, which never included any cold start emissions. increasing idle time increases hc concentrations as fig. 5 declines. also, increasing egr rates added to combustion chamber increased hc concentrations. the increments were 4.09, 11.06 & 17.21% for egr rates= 10, 20 & 30 respectively compared with adding 0% egr. idling time extension increased nox concentrations for egr=0% case, as fig. 6 reveals. but this extension reduced nox in the other studied cases. increasing idle time means increasing heat inside combustion chamber due to reduction in engine cooling abilities. increasing heat gives higher nox concentrations as a result. adding egr reduces combustion chamber temperature and the heat produced from combustion, this effect causes nox concentration to reduce. the effect of egr addition is to reduce nox and that is its duty. nox concentration reduced by about 9.11, 14.83 & 24.788% for egr rates= 10, 20 & 30% respectively compared with egr=0%. 0 0.02 0.04 0.06 0.08 0.1 0.12 0 10 20 30 40 m a x . c o c o n c e n tr a ti o n s (% v o l. ) idling time (min.) 17°btdc, 1000 rpm egr=0% egr=10% egr=20% egr=30% 60 70 80 90 100 110 120 0 10 20 30 40 h c c o n c e n tr a ti o n ( p p m ) idling time (min.) 17°btdc, 1000 rpm egr=0% egr=10% egr=20% egr=30% 40 50 60 70 80 90 0 10 20 30 40 n o x c o n c e n tr a ti o n ( p p m ) idling time (min.) 17°btdc, 1000 rpm egr=0% egr=10% egr=20% egr=30% miqdam tariq chaichan al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 3344 (2014) 38 fig. 7. idling time effect on smoke opacity for variable egr rates at oit and 1000 rpm. low combustion temperatures and nonstoichiometric oxygen conditions result in incompletely burned fuel, and various concentrations of particulates largely of carbon composition. engine emitted these fine particulates consisted of elemental carbon (ec), organic carbon (oc), metals from fuel and engines wear, and sulfates with bound water. egr effect on smoke opacity conflict with its effect on nox, as fig. 7 represents. increasing egr rates increased smoke opacity, as well as increasing idling time increased opacity. opacity reduction needs high temperatures to reduce smoke, while adding egr reduces these temperatures causing increment in opacity. increasing idling time increases heat slightly inside combustion chamber. but it also increases heterogeneous zones which causes many rich zones produces higher opacity. for 0% egr the increment in opacity because of increasing idling time was 10%. the increment in smoke opacity was 1.37, 4.26 & 8.27 for egr rates=10, 20 & 30% respectively compared to 0% egr. engine noise reduced slightly with increasing idle time from zero to 10 minutes, but it return to increase after that with engine idle continuing, as fig. 8 clarifies. adding egr reduces engine noise due to the relation between pressure rates inside combustion chamber and noise. egr addition reduces combustion efficiency and pressure rates as a result engine noise reduced. the reduction in engine noise was 2, 3.72 & 5.08% for egr rates =10, 20 & 30% compared to 0% egr. fig. 8. idling time effect on engine noise for variable egr rates at oit and 1000 rpm. 3.2. engine speed effect experiments were conducted on the engine to measure co, co2, nox, hc, opacity during idling conditions. period of 30 min. was used as idling time and injection timing was fixed at optimum injection timing. co2 emissions are a direct function of fuel consumption. during combustion, the products from the carbon in the fuel are co2, and the byproducts are co, hc, and formaldehydes. the majority of the carbon products are formed into co2, so as more fuel is consumed like by increasing engine idle speed, co2 concentrations increase, as fig. 9 reveals. fig. 9. engine speed effect on co2 concentrations for variable egr rates at oit for 30 min idling run. 6 6.5 7 7.5 8 8.5 9 0 10 20 30 40 m a x . o p a c it y ( % ) idling time (min.) 17°btdc, 1000 rpm egr=0% egr=10% egr=20% egr=30% 78 79 80 81 82 83 84 85 86 87 88 0 10 20 30 40 m a x . n o is e (d b ) idling time (min.) 17°btdc, 1000 rpm egr=0% egr=10% egr=20% egr=30% 5.7 5.8 5.9 6 6.1 6.2 6.3 6.4 6.5 500 700 900 1100 m a x . c o 2 c o n c e n tr a ti o n ( % v o l. ) engine speed (rpm) 17°btdc, 30 min. idling egr=0% egr=10% egr=20% egr=30% miqdam tariq chaichan al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 3344 (2014) 39 co2 concentrations increased about 9.15% with increasing idle speed from 600 to 1000 rpm. adding egr reduced these concentrations for the tested range. increasing engine speed increases air and heat inside combustion chamber resulting in better combustion. better combustion means higher co2 concentrations. fig. 10. engine speed effect on co concentrations for variable egr rates at oit for 30 min idling run. co concentrations behave in the opposite of co2, as fig. 10 manifests. increasing idle speed reduced co concentrations with about 23.63%. while increasing egr rates increased co concentration, for the same reason mentioned previously. the increments were 4.8, 10.9 & 16.18% for egr=10, 20 & 30% respectively compared to 0% egr. fig. 11 shows idle engine speed effect on hc concentrations for several egr rates. hc concentrations behave as co concentrations for same reasons. it reduced with increasing engine idle speed with about 24.28%. while it increased with increasing egr rates. increments were 3.24, 5.67 & 10.27% for egr=10, 20 & 30% respectively compared to 0% egr. fig. 11. engine speed effect on hc concentrations for variable egr rates at oit for 30 min idling run. egr duty is to reduce nox and that what fig. 12 demonstrates. nox concentrations reduced with increasing egr rates, and it reduced even more with increasing idle speed on the contrary of 0% egr case. in the normal case increasing idle speed means increasing air and heat inside combustion timing with available time for formation (where idle speeds can be considered low speeds). in this case, increasing egr rates improved its effect with time (it must be put in mind those measuring max. concentrations after the engine idling for half an hour). low speed idling made many rich zones in combustion chamber which produced local high temperatures even with egr addition due to reduction in turbulence inside combustion chamber. the reduction in concentrations were 3.63, 9.44 & 13.55% for egr rates= 10, 20 & 30% respectively compared with egr=0%. fig. 12. engine speed effect on nox concentrations for variable egr rates at oit for 30 min idling run. fig. 13. engine speed effect on smoke opacity for variable egr rates at oit for 30 min idling run. smoke opacity reduced with increasing idle speed, but it increased with egr addition, as fig. 13 demonstrates. increasing engine speed (from 0.06 0.07 0.08 0.09 0.1 0.11 0.12 0.13 0.14 500 700 900 1100 m a x . c o c o n c e n tr a ti o n ( % v o l. ) engine speed (rpm) 17°btdc, 30 min. idling egr=0% egr=10% egr=20% egr=30% 50 55 60 65 70 75 80 500 700 900 1100 m a x . h c c o n c e n tr a ti o n ( p p m ) engine speed (rpm) 17°btdc, 30 min. idling egr=0% egr=10% egr=20% egr=30% 50 55 60 65 70 75 500 700 900 1100 m a x . n o x c o n c e n tr a ti o n ( p p m ) engine speed (rpm) 17°btdc, 30 min. idling egr=0% egr=10% egr=20% egr=30% 7.4 7.6 7.8 8 8.2 8.4 8.6 8.8 500 700 900 1100 m a x . o p a c it y ( % ) engine speed (rpm) 17°btdc, 30 min. idling egr=0% egr=10% egr=20% egr=30% miqdam tariq chaichan al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 3344 (2014) 40 very low speed as 600 rpm to moderate speed as 1100 rpm) increases combustion efficiency and reduces opacity. egr effect resists this effect, but the available results indicate that increasing combustion efficiency overcomes egr effect. opacity increments were 1.16, 2.23 & 4.64% for egr rates=10, 20 & 30% respectively compared to 0% egr. engine noise increased with adding egr at low speeds and reduced for higher speeds compared with no egr addition, as fig. 14 represents. at low idle speeds engine vibration increased highly causing high noise rate, while at higher idle speeds large reduction in engine vibration achieved causing lower noise. adding egr in good combustion conditions results in reduction in engine noise, arising from reduction in pressure combustion rates accompanied with this addition. fig. 14. engine speed effect on engine noise for variable egr rates at oit for 30 min idling run. 3.3. injection timing effect co2 concentrations reduced with retarding injection timing from oit highly, and it reduced slightly with advancing it also, as fig. 15 reveals. retarding it causes late combustion which means part of it will be in the expansion stroke; result in less power and lower exhaust temperatures. these factors causes bad combustion which produces low co2 concentration, associated with higher co and hc concentrations (figs. 16 & 17) at these it. advancing it increases pressure rates and heat produced inside combustion chamber resulting in better combustion. this combustion improvement doesn’t affect co2 while it reduces co and hc concentration highly as figs 15, 16 & 17 represent. retarding injection timing was considered one of the treatments can be used to reduce nox concentrations. egr addition with retarding it together caused lower nox concentration, as fig. 18 reveals. contrary to opacity which increased highly with these two factors accompanied as fig. 19 represents. the conditions reversed at advancing it, where heat and available time increased generating more nox concentrations. in this region two conflicting factors applied and egr addition still reducing nox (fig. 18) and increases opacity (fig. 19). fig. 15. injection timing effect on co2 concentrations for variable egr rates at oit for 30 min idling run. fig. 16. injection timing effect on co concentrations for variable egr rates at oit for 30 min idling run. engine noise increased highly with egr addition and it retarding, as fig. 20 shows. retarding engine it increased engine vibration, while adding egr made combustion more difficult, and the result higher engine noise. in contrast to the former mentioned, adding egr with advanced it reduced noise. advancing it increases produced pressure rates from combustion witch increases noise, while adding egr reduces noise. the resultant from applying these two factors clarifies that egr effect is dominant, as the figure insures. 80 82 84 86 88 90 92 94 96 98 500 700 900 1100 m a x . n o is e (d b ) engine speed (rpm) 17°btdc, 30 min. idling egr=0% egr=10% egr=20% egr=30% 5 5.5 6 6.5 7 10 15 20 25 m a x . c o 2 c o n c e n tr a ti o n s (% v o l. ) injection timing (°btdc) 1000 rpm, 30 min. idling egr=0% egr=10% egr=20% egr=30% 0.06 0.07 0.08 0.09 0.1 0.11 0.12 0.13 0.14 10 15 20 25 m a x . c o c o n c e n tr a ti o n s (% v o l. ) injection timing (°btdc) 1000 rpm, 30 min. idling egr=0% egr=10% egr=20% miqdam tariq chaichan al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 3344 (2014) 41 fig. 17. injection timing effect on hc concentrations for variable egr rates at oit for 30 min idling run. fig. 18. injection timing effect on nox concentrations for variable egr rates at oit for 30 min idling run. fig. 19. injection timing effect on smoke opacity for variable egr rates at oit for 30 min idling run. fig. 20. injection timing effect on engine noise for variable egr rates at oit for 30 min idling run. 3.4. comparison with other studies it is difficult to compare results of recent study with other similar ones, due to variable tests procedures and measurements. in fig. 21 a comparison of nox concentrations for three similar studies at engine speed 600 rpm and variable injection timing for each study. egr=20% results for recent study was chosen for this comparison depending on several studies like references 18 and 19 which confirm that using 20% egr gives the best results in reducing nox with limited effect on brake specific fuel consumption and thermal efficiency. brodrick [20] showed that nox concentrations reached its minimum values for idle period of 10-15 minutes after that it increased highly. hearne [21] results are similar to recent study except for the values at 5 min. which is high due to the measuring procedure for school bus and no egr employing. khan [22] studied several cars models and its effects on emissions at idle period. the study focused on models from 1965 to 2005. the average as it seemed in the figure high compared with recent study because egr was not used in the tested engine. finally, all results indicate high and hazard nox concentrations at idle time. 4. conclusions although the small data set reported here improves our knowledge of engine idle emissions, a number of important questions remain unanswered. data from many more engines from a broader range of manufacturers and using years and maintenance quality are necessary for accurate emissions factors that can be used in air quality modeling. this study insures the need for 50 55 60 65 70 75 80 10 15 20 25 m a x . h c c o n c e n tr a ti o n s (p p m ) injection timing (°btdc) 1000 rpm, 30 min. idling egr=0% egr=10% egr=20% egr=30% 50 55 60 65 70 75 80 10 15 20 25 m a x . n o x c o n c e n tr a ti o n s (p p m ) injection timing (°btdc) 1000 rpm, 30 min. idling egr=0% egr=10% egr=20% egr=30% 7.2 7.4 7.6 7.8 8 8.2 8.4 8.6 8.8 9 10 15 20 25 m a x . o p a c it y ( % ) injection timing (°btdc) 1000 rpm, 30 min. idling egr=0% egr=10% egr=20% egr=30% 80 82 84 86 88 90 92 94 96 98 100 10 15 20 25 m a x . n o is e (d b ) injection timing (°btdc) 1000 rpm, 30 min. idling egr=0% egr=10% egr=20% egr=30% miqdam tariq chaichan al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 3344 (2014) 42 quick action from iraqi government and civil society enterprises to educate iraqi drivers about long idling time risks from economic and health point of view. idle emissions of co, hc, nox, smoke, noise and co2 at idle have been presented in this paper. three variables were used to test engine emissions when idling with egr addition in several rates. the tested variables were idling time, engine speed variation and injection timing variation. the results indicate that: fig. 21. comparison of recent study with other similar studies.  co2 concentrations increased with increasing idle time and engine speed, but it didn’t show clear effect for it advancing. in contrast, retarding it reduced these concentrations. operating the engine with egr addition caused a reduction for co2 concentration through idle time, increasing engine speed and with it variation.  co concentrations reduced in the first 10 min. of the engine idling period, and then it increased if this period continued. co reduced with increasing engine speed and advancing it. adding egr increased co for all the studied tests.  hc concentration increased with idle time advance, but it reduced with increasing idle speed and advancing engine it. adding egr increased hc for all the studied tests.  nox concentrations reduced with adding egr for all the tested variables. nox concentrations increased with increasing idle time, engine speed and advancing it.  smoke opacity increased with increasing idle time and retarding it. while it reduced with increasing engine speed and advancing it. using egr increased opacity for all tested cases.  egr addition reduced engine noise for all tested cases. engine noise increased with increasing idle time and retarding it. noise reduced with increasing idle speed and advancing it. notation btdc before top dead centre co carbon monoxide co2 carbon dioxide db decibel egr exhaust gas recirculation hc unburnt hydrocarbon it injection timing nox nitrogen oxides pm particulate matters so smoke opacity 5. references [1] last b, houben h, rottner m, stotz i, influence of modern diesel cold start systems on the cold start, warm-up and emissions of diesel engines, beru ag, germany, 2008. [2] national academy of sciences (nas), technologies and approaches to reducing the fuel consumption of medium and heavy-duty vehicles, washington d.c., the national academies press, 2010. [3] lutsey n; brodrick c j; sperling d and oglesby c, heavy-duty truck idling characteristics: results from a nationwide survey. transportation research record no. 1880, trb, national research council, washington, d.c., pp: 29–38, 2004. [4] gaines l; vyas a d and anderson j l, estimation of fuel use by idling commercial trucks, transportation research board annual meeting 2006 paper #06-2567, 2006. [5] denning c and kustin c, the good haul: innovations that improve freight transportation and improve the environment, environmental defense fund, new york, ny 2010. [6] ham c, diesel fuel emissions and truck idling: the oregon interstate 5 idle-free corridor project a bounded rationality perspective, m sc thesis, political science, cascades campus, 2008. [7] carrico amanda c r, paul padgett p, michael p, vandenbergh jonathan gilligan v j and kenneth a. wallston k a, costly 40 60 80 100 120 140 160 5 10 15 20 25 30 n o x c o n c e n tr a ti o n s (p p m ) time (min.) 10°btdc, 600 rpm brodrick, 2002 hearne, 2003 khan, 2006 recent study miqdam tariq chaichan al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 3344 (2014) 43 myths: an analysis of idling beliefs and behavior in personal motor vehicles, energy policy, vol. 37, no. 8, pp: 2881-2888, august, 2009. [8] proc k, nitschke b, wagner f, anderson m, slezak l, idle reduction technology demonstration plan, national renewable energy laboratory, report no. nrel/tp540-34872, 2003. [9] stephanie g and mee c, toronto public health, improving toronto’s idling control bylaw, technical report, toronto, ontario, 2009. [10] khan a s, clark n , thompson g j, wayne w s, gautam m, lyons d w and hawelti d, idle emissions from heavy-duty diesel vehicles: review and recent data, j. air & waste manage. assoc, vol. 56, pp: 1404– 141, 2006. [11] usepa “united state environment protection agency”: smart way transport, 2009. available at: http://www.epa.gov/smartway/transport/inde x.htm. [12] united states environmental protection agency office of solid waste and emergency response, green remediation best management practices: clean fuel & emission technologies for site cleanup, (5102g) epa 542-f-10-008, august 2010 [13] kinsey j s, williams d c, dong y and logan r, clean school bus study, united states environmental protection agency (usepa). 2007. available at: http://www.epa.gov/region2/cleanschoolbus/s tudy.html. [14] downing k and matthews s, improving truck efficiency and reducing idling, submitted to: house interim committee on environment and water, october, 2010. [15] environmental defense, the clean air task force and the conroe independent school district, measuring pollution levels inside texas school buses, 2007. available at: http://www.edf.org/documents/6153_bus_fin dings.pdf. [16] diane b, berry p, bouchet v, charron d and clarke k l, human health in a changing climate: a canadian assessment of vulnerabilities and adaptive capacity, health canada. 2008. available at: http://www.hc-sc.gc.ca/ewhemt/climat/eval/index-eng.php#guide. [17] energy information administration, annual energy outlook 2010, doe/eia-0383 (2010), washington, d.c., may, 2010. available at: http://www.eia.doe.gov/oiaf/aeo/ [18] chaichan m t & saleh a m, practical investigation of the effect of egr on di multi cylinders diesel engine emissions, anbar journal for engineering science (ajes), vol. 6, no. 3, pp: 401-410, 2013. [19] ghazikhani m, feyz v & joharchi a, “experimental investigation of the exhaust gas recirculation effects on irreversibility and brake specific fuel consumption of indirect injection diesel engines”, applied thermal engineering, vol. 30, pp: 1711-1718, 2010. [20] brodrick c j, dwyer h a, farshchi m, harris d b and king g k, effects of engine speed and accessory load on idling emissions from heavy-duty diesel truck engines, air & waste manage. assoc., vol.52, pp: 10261031, 2002. [21] hearne j s, school bus idling and mobile diesel emissions testing: effect of fuel type and development of a mobile test cycle, msc thesis, the faculty of rowan university, 2003. [22] khan a b m s, clark n n, thompson g j, wayne w s, gautam m, lyons d w and hawelti d, idle emissions from heavy-duty diesel vehicles: review and recent data, j. air & waste manage. assoc., vol. 56, pp: 14041419, 2006 (2014)3344 ، صفحت4، العذد10دجلت الخىارزمي الهنذسيت المجلمقذام طارق جيجان م وحىقيج الحقه على الملىثاث المنبعثت خالل (egr)حأثير حذوير الغاز العادم دراست عمليت ل فخرة الحياد مقذام طارق جيجان ةاىجاٍعت اىخنْىىىجً /قسٌ هْذست اىَنائِ واىَعذاث miqdam_tc@uotechnology.edu.iq: اىبشٌذ األىنخشوًّ الخالصت حقذً هزة اىذساست . حقٍٍذ هزة اىفخشة بقىاٍِّ ٍيضٍتاىى اَُ ىٌ ٌخٌ ، واىحٍاد ٍذةخاله اىذٌضه ىيخذٍت اىثقٍيت اىىقىد وحقيو ٍِ ّىعٍت اىجىحسخهيل سٍاساث (co)ُ سبىامسٍذ اىلوإر دسسج ٍيىثاث اىحٍاد ألوه ا. ٍعيىٍاث شاٍيت ٍشحبطت بْخائج عَيٍت حَج عيى ٍحشك دٌضه ري حقِ ٍباشش ٍخعذد األسطىاّاث ، عْذ اضافت ثالد ّسب واىضىضاء (co2)سبىُ امسٍذ اىلووعخىٍت اىذخاُ وثاًّ ا( nox)وأماسٍذ اىٍْخشوجٍِ ( hc)واىهٍذسوماسبىّاث غٍش اىَحخشقت .ٍخخيفت ٍِ اىغاص اىعادً اىَذوس اىى ٍشعب اىذخىه ىنو األخخباساث coوحضداد حشامٍض . ىخقذٌٌ حىقٍج اىحقِ اواضح احأثٍشوسشعت اىحٍاد ىيَحشك، ىنْها ىٌ حظهش بضٌادة صٍِ اىحٍاد co2حضداد حشامٍض noxحقو حشامٍض . بخقذً حىقٍج اىحٍاد، وىنْها قيج بضٌادة سشعت اىحٍاد وحقذٌٌ حىقٍج اىحقِ hc، مَا صادث حشامٍض (egr)باضافت غاص عادً ٍذوس وحضداد عخىٍت . اىخشامٍض بضٌادة صٍِ اىحٍاد وسشعت اىَحشك وحقذٌٌ حىقٍج اىحقِ ٓوىنو اىَخغٍشاث اىَذسوست، وحضداد هز egrباضافت غاص عادً ٍذوس ضىضاء اىَحشك ىنو egrحقيو اضافت . صادث عخىٍت اىذخاُ ىنو اىحاالث اىَذسوست egrاىذخاُ بضٌادة صٍِ اىحٍاد وحأخٍش حىقٍج اىحقِ، وباسخخذاً .وحأخٍش حىقٍج اىحقِ اىحاالث اىَخخبشة، وحضداد اىضىضاء بضٌادة صٍِ اىحٍاد mailto:miqdam_tc@uotechnology.edu.iq (microsoft word \317 \332\341\355 \346\315\344\307\34422-29) al-khwarizmi engineering journal al-khwarizmi engineering journal,vol. 13, no. 4, p.p. 2229 (2017) optimization of material removal rate and temperature in magnetic abrasive finishing process for stainless steel 304 ali h. kadhum* hanan h. murad** *, ** department of automated manufacturing engineering / al-khwarizmi college of engineering / baghdad university *email: kadhumali59@yahoo.com **email: hananhasan729@yahoo.com (received 3 january 2017; accepted 20 june 2017) https://doi.org/10.22153/kej.2017.06.001 abstract the effect of the magnetic abrasive finishing (maf) method on the temperature rise (tr), and material removal rate (mrr) has been investigated in this paper. sixteen runs were to determine the optimum temperature in the contact area (between the abrasive powder and surface of workpiece) and the mrr according to taguchi orthogonal array (oa). four variable technological parameters (cutting speed, finishing time, working gap, and the current in the inductor) with four levels for each parameter were used, the matrix is known as a l16 (44) oa. the signal to noise ratio (s/n) ratio and analysis of the variance (anova) were utilized to analyze the results using (minitab17) to find the optimum condition and identify the significant parameters affecting on the tr., and mrr of the steel 304. ir camera was used to measure the experimental temperature. the results showed that the optimum temperature in contact area of workpiece is 70.7 °c. keyword: ir camera ,magnetic abrasive finshing , temprature rise. 1. introduction magnetic abrasive finishing (maf) process is the one in which material is removed in such a way that the surface is finished. the most uses of maf are manufacturing semiconductors, medical instruments, atomic energy parts and aerospace components that have a very precise surface roughness [1]. one of the main advantages of maf operation as compared with traditional finishing operations is the minimizing of the possibility of micro cracks on the surface of the workpiece, because the cutting force is primarily controlled by the magnetic field [2]. the principle work of magnetic abrasive finishing involves filling the working gap between the workpiece and the pole with the magnetic abrasive powder, the current or the magnetic flux density is passed through the coil to produce the magnetic field, and the pole is rotating with the powder along the work piece. the magnetic field provides the abrasive powder with the energy, this energy makes the magnetic abrasive powder as a cutting tool for treating the surface, and the rotation of the pole makes the friction between the workpiece and the magnetic abrasive powder which the material can be removed from the workpiece [3-4]. maf was inventoried by harry p. coat in 1938’s in u.s.a, the first patent was given in1940’s, the research began in the universities of germany, and soviet union in 1960’s and particularly appeared during 1980’s, 1990’s [5]. many of the parameters, like number of the turns, and magnetic flux density affect on the materials removal rate [6]. girma b. et al. [7] explored the maf process by analyzing the materials removal rate and the surface roughness using response surface method in plane surfaces. it was concluded that the current, ratio size and the magnetic abrasive powder grain size are more ali h. kadhum al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 2229 (2017) 23 effective on the material removal rate. the maf process, the thermal effect of electromagnetic flux in the coil produced from current and from the friction between the magnetic abrasive powders with workpiece. vivek mishra et al. [8] used the finite element method in the magnetic abrasive finishing process. the friction between the magnetic abrasive particles and the surface of the workpiece leads to frictional heating in the working zone of the surface, based on the ansys software to simulate the temperature and the magnetic field. the factors used were the magnetic flux density (0.233t) at (0.91a), it was found that the temperature was between (34– 51◦c). chandan gaur [9] applied the voltage and the working gap as parameters, and is used minitab17 to obtain regression model to analyze the data, the result showed that the temperature increased with increasing the voltage and decreasing the machining gap. the maximum temperature during this process was 94.7 ◦c. it was concluded that the effect of the temperature during the maf process is very small on the quality of the surface roughness, and there is no any conclusion on the various parameters. singh et al. [10] according to the taguchi’s design of experiments planned, used four parameters (working gap, voltage, and mesh number size of the abrasive and rotational speed). the result showed that the working gap and the voltage are more effective on the change in the surface roughness (δra). the objective of this work is: 1-optimization the maf parameters through the materials removal rate, and determining the optimum temperature according to optimum mrr of stainless steel 304 2studying the influence of maf parameters (cutting speed, finishing time, working gap, and current in the coil) on the mrr. 2. experimental work 2.1. selection of maf process parameters and their levels in this research, four parameters were considered to be effective on the temperature in the maf process, these chosen parameters are (rotational speed, working time, current, and working gap) with four levels for each parameter. the selected parameters and their levels are listed in the table 1; these parameters were selected based on the initial experiments. table 1, the selected parameters and their levels. 2.2. selection of the orthogonal array the experiments were designed based on the orthogonal array (oa) technique to reduce the number of the experiments. from the minitab17 software and by total degree of the freedom (dof) needed to be computed, in order the select the appropriate oa for the experiments, each variable with four levels has two degrees of freedom. based on taguchi method, the total dof of selecting oa must be greater than or equal to the total dof required for the experiment; therefore, an orthogonal array l16 (4�) for the four factors with the four levels was used in the present investigation to perform the most effective experiments (16 experiments) from the overall experiments (256 experiments). 2.3. experimental procedure of maf process in this work, sixteen different tests are designed based on the taguchi oa l16. stainless steel 304 is used as flat workpiece with dimensions (100×50×3) mm. the chemical composition of stainless steel 304 is explained in the table 2 no. parameters unit code levels 1 rotational speed rpm a 250 500 750 1000 2 working time min b 5 10 15 20 3 current amp c 1.5 2 2.5 3 4 working gap mm d 1 1.25 1.5 1.75 ali h. kadhum al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 2229 (2017) 24 table2, the chemical composition of the stainless steel 304. the physical properties of stainless steel 304 are listed as in the table 3. table 3, the physical properties of stainless steel 304. density (kg/m3) elastic modulus (gpa) coefficient of thermal expansion (μm/m/°c) 0100°c thermal conductivity (w/m.k) at 100°c 8000 193 17.2 16.2 specific heat (j/kg.k) 0-100°c electrical resistivity (nω.m) 500 720 in the maf process, an electromagnetic inductor was manufactured because it plays an important role in the finishing the surface layer. the inductor consists of the following: the core is from low carbon steel, the diameter of core is 22 mm, and the length of the core is 280 mm, while the diameter of the wire of coil is 0.9 mm, number of turns is 2400 for the primary coil and 1600 for the secondary coil, as shown in the fig.1. a conventional “turret vertical milling machine model: mdm 4vs/4hs/4s’’ with its spindle was used to fix the magnetic inductor. this work is implemented on the workshop in the college. fig. 1. the coil in the maf process. before maf process, the weight of the stainless steel 304, was measured the workpiece was fixed by a special fixture to clamp the flat surface on the table, as shown in the fig .2. fig. 2. fixing the workpiece in the maf process. in the maf process, the parameters for all 16 experimental tests were adjusted, the gap between the workpiece and the pole was first measured by the verne instrument, and then filled with the ma powder, then the coil was provided with the current through the dc power supply. after that adjustment, the cutting speed was measured by the tachometer, and then the time was adjusted by using a timer. a properly calibrated infrared camera was used measure the temperature in the contact region during finishing of workpiece at the last two second by. the fringe pattern readily changes with the change in any technological parameters, affecting the cutting temperature. the equation for measuring the mrr (g/min) is: mrr � � �� ����� ��� ��� � ����� �� �.�.���� … (1) w: is the weight of the workpiece (g). chemical analysis of stainless steel 304 c si mn cr ni mo cu 0.07 0.9 1.4 20.3 9.2 0.12 0.17 p s chemical composition standard c si mn cr ni mo cu 0.08 max 1 max 2 max 1820 810.5 p s 0.045 max 0.03 max ali h. kadhum al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 2229 (2017) 25 3. results and discussion 3.1. signal to noise ratio (s/n) the s/n ratio is defined as a standard approach used for the average of the result in run with the main parameter. the optimum with s/n ratio is studying the main effect of the parameters and giving the best result which effect on the process [11]. in the maf process, the s/n ratio is used to measure the mrr with the parameters, there are three categories of the quality characteristics: smaller is better, normal is better and bigger is better, in this case selecting the bigger is better which means the maximum response of the mrr. the mean squared deviation (msd) and (s/n) ratio are determined by the equations: �� � ! "∑ $ !%&'() "*+! ...(2) �/� −10123!4 5!"∑ ! %&'( "*+! 6 ...(3) where: n: number of trails 7*89 : the total result of the trails table 4, design of the experiments and result of the mean, s/n ratio for mrr the stainless steel 304. 3.1.1. optimization of the maf process parameters with mrr of stainless steel 304 in this study, the results of the mrr of the stainless steel 304 with factors are analyzed by s/n ratio, to obtain the influence of the levels of the parameters on the quality of the surface; the mean and the s/n ratio are given in table 4. the main effect of each parameter with four levels on the mean and s/n ratio for mrr stainless steel 304 are calculated and listed in the table 5. no. of exp. a (rpm) b (min) c (amp) d (mm) mrr steel (g/min) s/n ratio mean (g/min) tr. (°c) 1 250 5 1.5 1 0.0155 -36.1934 0.0155 28 2 250 10 2 1.25 0.0090 -40.9151 0.0090 24.1 3 250 15 2.5 1.5 0.0400 -27.9588 0.0400 49.6 4 250 20 3 1.75 0.0350 -29.1186 0.0350 68.5 5 500 5 2 1.5 0.0278 -31.1191 0.0278 35.9 6 500 10 1.5 1.75 0.0263 -31.6009 0.0263 32.8 7 500 15 3 1 0.0399 -27.9805 0.0399 54.9 8 500 20 2.5 1.25 0.0465 -26.6509 0.0465 70.3 9 750 5 2.5 1.75 0.0178 -34.9916 0.0178 22.3 10 750 10 3 1.5 0.0330 -29.6297 0.0330 41.5 11 750 15 1.5 1.25 0.0300 -30.4576 0.0300 34.1 12 750 20 2 1 0.0349 -29.1435 0.0349 39.9 13 1000 5 3 1.25 0.0480 -26.3752 0.0480 41.9 14 1000 10 2.5 1 0.0298 -30.5157 0.0298 40.3 15 1000 15 2 1.75 0.0350 -29.1186 0.0350 35.0 16 1000 20 1.5 1.5 0.0200 -33.9794 0.0200 29.2 ali h. kadhum al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 2229 (2017) 26 table 5, the effect of the (s/n) ratio and mean of mrr stainless steel 304. s/n ratio optimization mean optimization from the table 5, the optimum parameters of the s/n ratio when (a2, b3, c4, and d3) (a= 500rpm, b= 15min, c= 3a, and d= 1.5mm) as shown in fig. 3. and for mean effect in the (a2,b3,c4,andd2)(a=500rpm,b=15min,c=3a,an d d=1.25mm) as shown in fig. 4. the values of the s/n ratio and mean in table (5) are calculated from minitab software. the delta is a difference between maximum value and minimum value, for example (-29.34 +-33.55) = 4.21. although the rank of the s/n ratio and the means is the same, but this state need to make prediction, because the working gap value is different for two plots in fig (3, 4). the prediction is used to determine the optimum value by choosing the large value of the s/n ratio in the prediction, as shown in the table 6. fig. 3. the s/n ratio effect on the parameters of stainless steel 304 on the mrr. fig. 4. the mean effect on the parameters of stainless steel 304 on the mrr. :∆mrr < =�>� = � ?̅abc + efabc + g̅abc + habc − 3jfk ...(4) where: jf � the overall mean of response mrr. ?̅abc , efabc , g̅abc , mno habc = the average of response at the optimum level. from the table 6, the optimum conditions of the mrr stainless steel 304 when (a= 500rpm, b=15min,c=3a, and d=1.5mm), and the temperature in the optimum experiment is 70.7°c 1 000750500250 -28 -29 -30 -31 -32 -33 -34 201 51 05 3.02.52.01 .5 1 .751 .501 .251 .00 rotational speed m e an o f s n r a ti o s working time current working gap main effects plot for sn ratios data means signal-to-noise: larger is better 1 000750500250 0.040 0.035 0.030 0.025 201 51 05 3.02.52.01 .5 1 .751 .501 .251 .00 rotational speed m e a n o f m e a n s working time current working gap main effects plot for means data means the s/n ratio effect level a b c d 1 -33.55 -32.17 -33.06 -30.96 2 -29.34 -33.17 -32.57 -31.10 3 -31.06 -28.88 -30.03 -30.67 4 -30.00 -29.72 -28.28 -31.21 delta 4.21 4.29 4.78 0.54 rank 3 2 1 4 the means effect level a b c d 1 0.02488 0.02728 0.02295 0.03002 2 0.03513 0.02452 0.02668 0.03338 3 0.02892 0.03623 0.03352 0.03020 4 0.03320 0.03410 0.03897 0.02853 delta 0.01025 0.01170 0.01602 0.00485 rank 3 2 1 4 ali h. kadhum al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 2229 (2017) 27 table 6, the prediction of the mean and s/n ratio. s/n ratio a b c d 2 3 4 3 mean s/n ratio 0.0489312 -24.2117 mean a b c d 2 3 4 2 mean s/n ratio 0.0521062 -24.6396 3.2. the analysis of variance anova of the mrr stainless steel 304 anova was used to determine the effect of parameters with mrr and ra, the results showed that the pole geometry and time are more effected on the mrr [12]. in order to obtain percentage of the effect of all parameters (a,b,c,d) on the materials removal rate of the stainless steel 304 surface, anova was used to predict which parameter has a significant effect on the mrr, the contribution p% of each factors is explained in the table 7. table 7, anova for mrr stainless steel 304. source dof adj ss f p (%) a 3 0.0002512 0.49 14.022 b 3 0.0003673 0.72 20.503 c 3 0.0006104 1.19 34.073 d 3 0.0000499 0.10 2.785 error 3 0.0005126 28.614 total 15 0.0017914 where: dof: degree of freedom adj ss: adjusted sum of squares f: f value or fisher factor, measurement of the significance of the factor p%: percentage contributed of each factor. the contribution of all factors is also manifested in fig. 5. from this figure, it is noticed that the current (c) is more influence on the mrr, following by the working time (b), rotational speed (a) and then working gap (d), because the current and the working time lead to increase the heating in the maf process, the heating effected on the surface layer of the workpiece and on the mrr. fig. 5. contribution of the parameters in the mrr stainless steel 304. 3.3. the regression of the mrr of the stainless steel 304 with temperature the regression is used to define the relationship between the temperatures with the mrr of the stainless steel 304, see fig .6. the results of the mrr stainless steel 304 with temperature are listed in the table 4; the temperature was measured during the experimental work for 16 experiments by infrared camera. fig.6. the relationship between the temperature and mrr of steel. where: x: temperature of the stainless steel 304. fig.6. we shows the relationship between the temperature and the mrr of stainless steel 304. is noticed that increasing the stainless steel 304 temperatures caused to increase mrr when the temperature is about (60°c) then after that decreases because the value of the temperature degree is obtained from the effect of the four 706050403020 0.05 0.04 0.03 0.02 0.01 s 0.0055352 r-sq 77.8% r-sq(adj) 74.3% x m r r ,s t fitted line plot mrr = 0.03897 + 0.002771 x 0.000023 x^2 ali h. kadhum al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 2229 (2017) 28 parameters at each experiment. the optimum temperature is mean temperature which measured by the optimum conditions when (a= 500 rpm, b=15 min, c= 3a, and d=1.5 mm), fig. 7. is explains the infrared camera at optimum conditions. fig. 7. infrared photography for optimum conditions. 4. conclusions from the previous results, the followings can be concluded: 1the optimum temperature rise is obtained according to optimum mrr (maximum) ,for the steel 304 the optimum levels are (a2, b3, c4, and d3) when rotational speed is (500 rpm), working time is (15 min),current is (3a) and working gap is (1.5mm) ,and then the optimum temperature at these levels is tr=70.7°c. 2the analysis of the variance for the materials removal rate, it is noticed that the current (c) is more influential on the mrr, followed by the working time (b), rotational speed (a) and then working gap (d). 3mrr of the steel 304 is increasing when the temperature increase up to 60 °c. 5. references [1] mithlesh sharma,and devinder pal singh” ,to study the effect of various parameters on magnetic abrasive finishing”, international journal of research in mechanical engineering & technology vol. 3, issue 2, may oct 2013. [2] s. jayswal, v. jain, and p. dixit, “modeling and simulation of magnetic abrasive finishing process”, international journal of advanced manufacturing technology, vol.26, pp. 477– 490, 2005. [3] tae-wan kim” application of magnetic abrasive polishing to composite materials”, journal of mechanical science and technology, vol 5, pp 1029-1034, 2010. [4] japman singh, and radhey sham “experimental investigation of process parameter of maf on surface roughness, “international journal of the science, technology and management,‘sgi reflection ‘ may 2013. [5] yamaguchi h, and sato t, “polishing and magnetic field-assisted finishing“, intelligent energy field manufacturing interdisciplinary process innovations, 2012. [6] rishi devi joshi,.gursewak singh brar, and mithlesh sharma.”effect on magnetic abrasive machining with different range of the electrical parameters “,international journal of emerging technology and advanced engineering , vol.4,issue 9,sep 2014. [7] girma b., joshi s.s., raghuram m. v. g. s., and balasubramaniam r., “an experimental analysis of magnetic abrasive finishing of plane surfaces”, machining science and technology, vol. 10, issue 3, pp 323–340, 2006. [8] vivek mishra, harsha goel, rahul s. mulik, and p.m.pandey, “determining work-brush interface temperature in magnetic abrasive finishing process’ journal of manufacturing process,vol.16,issue 2,pp.248-256,2014. [9] chandan gaur “the analysis of the temperature during magnetic abrasive finishing of the plane plate “international journal for scientific research & development” vol. 3, issue 4, pp. 1835-1841, 2015. [10] dhirendra k. singh, v.k. jain, and v. raghuram, “parametric study of magnetic abrasive finishing process”, journal of materials processing technology, vol.149, issue 1-3, pp.22-29, 2003. [11] ranjit k. roy,”aprimer on the taguchi method,1st edition ,new york: van nostrand reinhold ,1990. [12] m. k. qate’a , a. .h. kadhum, f. f. mustafa ,”the influence of the magnetic abrasive finishing system for cylinder surface on the surface roughness and mrr” alkhwarizmi engineering journal ,vol. 11,no.3, pp. 1-10,2015. )2017(22-29 ، صفحة 4، العدد13دجلة الخوارزمي الهندسية المجلم علي حسين كاظم 29 معدن ل المغناطيسي الحكب التشغيل عملية خالل وللحرارة المزال للمعدن المثلى القيم ايجاد ٣٠٤ الفوالذ علي حسين كاظم* حنان حسن مراد** جامعة بغداد كلية الهندسة الخوارزمي / /قسم هندسة التصنيع المؤتمت ،*** kadhumali59@yahoo.com :البريد االلكتروني * hananhasan729@yahoo.com :البريد االلكتروني ** ةالخالص اجريت ست المواد من المعدن وكذلك على ارتفاع درجات الحرارة. الجلغ المغناطيسي على عملية ازالةفي هذا البحث سوف يدرس تأثير التشغيل ب زال هذه للمعدن المالمثلى غولة وكذلك اليجاد القيمةشالمثلى للحرارة فى منطقه االتصال بين مسحوق المعدن والقطعة الم عشرة تجربة اليجاد القيمة ارتفاع القطب هي ( سرعة القطب المغناطيسي وزمن التشغيل والتياروالعالم الياباني تاجوشي وذلك باستخدام اربعة مدخالت التجارب تتم وفقا لمصفوفة ) وتقنية (s/n ratioمستويات لكل مدخل. في هذا العمل سوف يطبق (نسبة األشارة الى الضوضاء) ةالمغناطيسي عن سطح المشغولة) مع وجود أربع أليجاد الشروط المثلى مع تعريف المدخالت المهمة التي تؤثر على (minitab17)وذلك باستخام البرنامج االحصائي anova) تحليل التباين ( عدن المذكور.أرتفاع درجات الحرارة ومعدل أزالة المادة للم 70.7 °c لى الحرارة المث العملية ان النتائج اظهرت ان درجةخالل التجارب ميرا الحرارية سوف تستخدم لقياس درجة الحرارةالكا .لمعدن الفوالذ al-khwarizmi engineering journal al-khwarizmi engineering journal,vol. 12, no. 2, p.p. 115123 (2016) experimental investigations performance for (vcc) using 2-way (pfcv) type (2fre) majid ahmed oleiwi department of control and systems engineering / university of technology email: majidoleiwi@yahoo.com (received 3 june 2015; accepted 12 november 2015) abstract in modern hydraulic control systems, the trend in hydraulic power applications is to improve efficiency and performance. “proportional valve” is generally applied to pressure, flow and directional-control valves which continuously convert a variable input signal into a smooth and proportional hydraulic output signal. it creates a variable resistance (orifice) upstream and downstream of a hydraulic actuator, and is meter in/meter out circuit and hence pressure drop, and power losses are inevitable. if velocity (position) feedback is used, flow pattern control is possible. without aforementioned flow pattern, control is very “loose” and relies on “visual” feed back by the operator. at this point, we should examine how this valve works and how can use it in electro-hydraulic circuit designs. in this paper, constructed and compared velocity control cylinder (vcc) by using a proportional flow control valve (pfcv) and with a fine throttle valve. with the aid of a check valve and that check valve, the proportional valve can be made to act in the “lift” direction, and the fine throttle in the “lower” direction. as with all proportional valves, there is also some hysteresis in a proportional flow control valve. the valve used in this work with a hysteresis of <±1% of maxq . the repetition accuracy is quoted in data sheet as < 1% of maxq . the inferential results are good, acceptable and useful for designers which are working at hydraulic proportional field. keyword: pfcv, vcc, experimental, investigation. 1. introduction proportional valve technology exactly does mean in hydraulic systems; an electrical input signal in the form of a voltage (mostly between 0 and+ 10v) is converted into an electrical current in an electronic amplifier corresponding to the voltage level, e.g.1 mv= 1 m a. proportionally to this electrical current as the input variable, the proportional solenoid produces the output variable-force and travel. these variables, i. e. force or travels, acting as the input signal for the hydraulic valve, signify proportionally a certain volumetric flow or pressure. for the consumer and therefore also for the working element of the machine this means , in addition to directional, steplessly variable control of speed and force. simultaneously, acceleration or deceleration can be steplessly varied, e. g. change in volumetric flow with respect to time [1]. hydraulic actuators are widely used on mobile equipment and robots, due to their high power density, environment tolerance, and compact size. one of the fundamental tasks in designing hydraulic actuating systems is the development of effective velocity control of the actuator using a control valve [2]. a practical approach to design a feed forward-plus-proportional-integralderivative (fpid) controller for accurate and smooth velocity control on a hydraulic linear actuator is presented [3,4,5,6,]. modeling and simulation a hydraulic servo system (hss) presented and describes the design and implementation of a control system for the operation of a electro hydraulic systems [3, 7, 8]. this paper presents explain and discus the 2-way proportional flow control valve to controls a flow rate depending on the set majid ahmed oleiwi al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 115123(2016) 116 electrical signal value, independently of pressure and viscosity. this means, for example, that a cylinder extends with constant velocity despite occurring interference variables (different loads). in the experimental work we will build a circuit in which the extension velocity of a cylinder can be changed the aid of a 2-way proportional flow control valve. the load independence of this circuit will be demonstrated on test bench figure (2) with the aid of the weight (30 kg). 2. steady state modeling generally, the steady state analysis cannot determine the complete performance of a valve because flow control valves contain moving parts. it used to obtain an estimate of valve characteristics. figure (1) explains the physical configuration of flow control valve. there are two orifices in valve. the first is constant size. the second is varying in size as the pressure drop across the spool,(𝑝𝑠 − 𝑝𝑣), changes. the spool has a spring force 𝑘𝑥 and preload force (f) [9, 10, 11, and 12]. ql ps qs pl kx f av pv pv variable orifice w(l.-x) av ps x fig. 1. schematic of physical analysis of flow control valves. the flow rate through the constant orifice is given by: 𝑄𝐿 = 𝐶𝑑𝐴𝑐 2(𝑝𝑠−𝑝𝑣) 𝜌 … (1) and flow rate through the constant orifice is given by: 𝑄𝐿 = 𝐶𝑑𝑤(𝑙𝑖 − 𝑥) 2(𝑝𝑠−𝑝 𝑙) 𝜌 … (2) combine equations (1, 2) yield an expression for 𝑝𝑣 : 𝑝𝑣 = 𝑨𝒄 𝟐𝑷𝒔−(𝝎 𝒍𝒊−𝒙 )𝟐𝑷𝑳 𝑨𝒄 𝟐+(𝝎 𝒍𝒊−𝒙 )𝟐 … (3) static equilibrium for spool valve is: 𝑝𝑠𝐴𝑣 = 𝑝𝑣𝐴𝑣 + 𝐹 + 𝑘𝑥 … (4) 𝑝𝑣 = 𝑝𝑠𝐴𝑣−𝐹−𝑘𝑥 𝐴𝑣 … (5) from equations (3 and 5) yield an expression: 𝑃𝑠𝐴𝑣−𝐹−𝑘𝑥 𝐴𝑣 − 𝐴𝑐 2𝑃𝑠−(𝜔 𝑙𝑖−𝑥 )2𝑃𝐿 𝐴𝑐 2+(𝜔 𝑙𝑖−𝑥 )2 = 0 … (6) solve equation (6) explicitly in the form cubic polynomial in x. when 𝐹 = 𝑚(𝑚𝑎𝑠𝑠) × 𝑔(acceleration) after calculating the spool displacement, x, at different of ps values, and from combining equations (1, 2) yield: 𝑄𝐿 = 𝐶𝑑 1 1 𝐴𝑐° 2 + 1 (𝜔 𝑙𝑖−𝑥 )2 2(𝑃𝑠−𝑃𝐿) 𝜌 … (7) where 𝐴𝑐 𝐶𝑜𝑛𝑠𝑡𝑎𝑛𝑡 𝑜𝑟𝑖𝑓𝑖𝑐𝑒 𝑎𝑟𝑒𝑎 𝑚2 𝜔 𝑉𝑎𝑟𝑖𝑎𝑏𝑙𝑒 𝑜𝑟𝑖𝑓𝑖𝑐𝑒 𝑎𝑟𝑒𝑎 𝑔𝑟𝑎𝑑𝑖𝑒𝑛𝑡 𝑚2/𝑚 𝑘𝑥 𝑆𝑝𝑟𝑖𝑛𝑔 𝑟𝑎𝑡𝑒 𝑁/𝑚 𝐶𝑑 𝑂𝑟𝑖𝑓𝑖𝑐𝑒 𝑑𝑖𝑠𝑐𝑕𝑎𝑟𝑔𝑒 𝑐𝑜𝑒𝑓𝑓𝑖𝑐𝑖𝑒𝑛𝑡 𝑙𝑖 𝐼𝑛𝑖𝑡𝑖𝑎𝑙 𝑣𝑎𝑟𝑖𝑏𝑙𝑒 𝑜𝑟𝑖𝑓𝑖𝑐𝑒 𝑜𝑝𝑒𝑛𝑖𝑛𝑔 𝑚 𝜌 𝐹𝑙𝑢𝑖𝑑 𝑑𝑒𝑛𝑠𝑖𝑡𝑦 𝑘𝑔 𝑚3 𝑃𝐿 𝐿𝑜𝑎𝑑 𝑝𝑟𝑒𝑠𝑠𝑢𝑟𝑒 𝑃𝑎𝑠𝑐𝑎𝑙 𝑃𝑠 𝑆𝑦𝑠𝑡𝑒𝑚 𝑝𝑟𝑒𝑠𝑠𝑢𝑟𝑒 𝑃𝑎𝑠𝑐𝑎𝑙 𝑄𝐿 𝐿𝑜𝑎𝑑 𝑓𝑙𝑜𝑤 𝑟𝑎𝑡𝑒 𝑚3 𝑠 3. pfcv (2 fre 6 b2x/...k4rv)technology proportional flow control valves model 2 fre are 2-way valves as shown in figure (2), they allow a preset electrical signal to control an oil flow independent of pressure and temperature variation [13]. the assembly consists of a housing (1), a proportional solenoid with inductive positional transducer (2), measuring orifice (3), pressure compensator (4) and check valve (5), if required. the oil flow required is set using a potentiometer (0 ... 100 %), which in turn gives an input value to amplifier type vt 5010. this in turn controls the orifice (3) via the proportional solenoid. the position of the orifice (3) is determined by the inductive positional transducer, and any difference from the given input value is then corrected by the control system. the pressure drop across the measuring orifice (3) is held constant by the pressure compensator (4). the oil flow is therefore independent of load. the low temperature drift is achieved by suitable design of the measuring orifice. at an input level of 0 % the measuring orifice is closed. in the event of electrical failure, or if the wire to the positional majid ahmed oleiwi al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 115123(2016) 117 transducer should break, the measuring orifice closes. a jump-free start is possible from the input value 0. the orifice may be opened and closed gradually by two ramps in the electronic amplifier. free flow from b to a is possible via the non-return valve (5). with an additional rectifier sandwich plate model z4 s 6mounted controlled both in meter-out and meter-in modes [14,15]. fig. 2. proportional flow control valve 2fre 6 b2x/…4rv [15 ]. 4. experimental work the hydraulic test bench shows in figure (3) have been proportional flow control valve. fig. 3. photograph of electrohydraulic control unit test bench [15]. 4.1. electrohydraulic control circuit complete the circuit diagram as shown in figure (4) so that the extension velocity of the cylinder can be controlled with the aid of a proportional flow control valve. it should be possible to alter the retraction velocity with the fine throttle. limit the system pressure with a suitable pressure relief valve direct operated (50 bar). m m proportional directional control valve pressure relief valve dbdh6k1x/100 variable displacement van pump motor tank check valve s8 a3 p t ba cylinder cg250/40/20 proportional flow control valve (2fre) throttle f5g3-3x fig. 4. schematic diagram of connection electrohydraulic control circuit. 4.2. electronic control circuit figures (5) explain the terminal connections / block circuit diagram electronic control: amplifiers model vt 5010 for velocity control. supposed and information for workers and engineers in the field of electro hydraulic control systems have special sciences facts. each servo or proportional valves has amplifier card. each company that produces these valves can product an electronic amplifiers card for its [15]. majid ahmed oleiwi al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 115123(2016) 118 fig. 5. terminal connections / block circuit diagram electronic control: amplifiers model vt 5010 for velocity control [15]. 5. dynamic considerations figure (6) is model of a 2-way proportional flow control valve. the 2-way proportional flow control valve is a self-contained closed control loop. the dynamics of such a closed control loop. a possible way of measuring the dynamic behavior of the flow control valve is to examine the so-called step-function. two possibilities are available: the stepwise change of specified signal value and the stepwise change of the interference variable (load pressure). step of interference variables can be subdivided into load steps and starting steps. by the term load steps is meant stepwise changes in load pressure that occur within the control range of a valve figure (7) range b, whilst starting steps are changes in load starting from the work points, that lie within the minimum pressure difference minp figure(7) range a. the greatest starting step occurs when the load connection of the flow control valve is opened. figure (8) shows a step response o a 2way flow control valve to a load step. the load pressure 2p acting on the valve is then suddenly reduced by opening the second throttle, which is connected in parallel. this leads to a temporarily increased flow rate because the valve requires a certain time (transient process) to match itself to the changed load pressure conditions (closed loop control) [9]. a further criterion of the dynamic behavior is the measurement of the frequency response. here, too, one distinguishes between change of signal value (control frequency response) and change of load (load pressure, interference frequency response). in measuring the control frequency response, the frequency of the control signal is continuously increased to “amplitude drop”, and produced consequent change of phase (phase lag). in concrete terms, this means ; the valve cannot longer follow the specified signal value above a certain frequency. in control engineering the term majid ahmed oleiwi al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 115123(2016) 119 “corner frequency” is introduced at this point. the comer frequency is that frequency at which the amplitude drop is 3 db. in measuring the interference frequency response for the control signal is held constant. for example in the flow control valve, the load pressure (interference variable) is varied. above a certain frequency of the interference variable, valve cannot longer able to compensate the interference variable when an amplitude drop and phase lag occurs [16, 17, 18, and 19]. p2 , q a ps u signal ff pmin = ps p1 = ff p1 fig. 6. model of a 2-way proportional flow control valve. fig. 7. qualitative characteristic curve of a flow control valve [16]. fig. 8. step response of a flow control valve to a step load [16]. 6. result and discussion all of evaluation experimental work data explain in tables (1, 2, 3, and 4). and characteristic curves (measured at  = 36 𝑚𝑚2 𝑠 and t = 50 °c. explanation of experimental results: figure (9) explain the characteristic curves for tables (1, 3). considering the two curves of characteristic curves 1, it is clear that the extension velocity is independent of the load (the two curves are practically identical). by adjusting the potentiometer and thereby the proportional flow control valve, the extension velocity can be changed independent of load according to characteristic curve (6 q) in figure (10). the velocity changes not proportionally, but progressively with the signal value. this characteristic curve, however, permits a finer adjustment of the velocity in low velocity ranges. figure (11) explain the characteristic curves for tables (2, 4). the curves of characteristic curves 2 are not dependent on the setting of the proportional flow control valve but only on the setting of the fine throttle. it can be clearly recognized that the retraction velocity with load is greater than that with no load. compare the two diagrams; then you can see the effect of the velocity control with the 2-way proportional flow control valve and the effect of velocity control with the fine throttle. with proportional flow control valve is load independent but with throttle load dependent. majid ahmed oleiwi al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 115123(2016) 120 table 1, extension hydraulic cylinder with no load. signal value of flow control valve (2 fre) 0 1 2 3 4 5 6 volt time without load 215.00 48.00 19.00 10.00 7.00 4.40 sec velocity without load 0.00 0.15 0.66 1.68 3.12 5.18 7.25 cm/s table 2, retraction hydraulic cylinder with no load. signal value of throttle 0 1 2 3 4 5 6 setting time without load 135.00 39.00 12.00 7.00 4.00 3.00 2.90 sec velocity without load 0.00 0.80 2.65 5.19 7.97 9.71 11.09 cm/s table 3, extension hydraulic cylinder with load. signal value of flow control valve (2 fre) 0 1 2 3 4 5 6 volt time with load 207.00 47.00 19.00 11.00 6.5 0 4.50 sec velocity with load 0.00 0.16 0.67 1.68 3.12 5.00 7.40 cm/s table 4, retraction hydraulic cylinder with load. signal value of throttle 0 1 2 3 4 5 6 setting time with load 103.00 29.00 10.00 5.50 4.00 2.50 2.30 sec velocity with load 0.00 1.12 3.45 6.91 10.71 12.94 14.78 cm/s fig . 9. characteristic curves for table 1 and 3. fig. 10. dependency flow rate on signal value voltage for different valve size [15]. 0 1 2 3 4 5 6 0 1 2 3 4 5 6 7 8 extension velocity signal value of voltmeter (volt) e x te n s io n v e lo c it y ( c m /s ) with out load with load majid ahmed oleiwi al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 115123(2016) 121 fig. 11. characteristic curves for table 2 and 4. 7. conclusions the results confirmed that the performance of velocity control cylinder (vcc) depends on the performance of the 2way proportional flow control valve (pfcv) type (2fre)  any variation in the value of fin throttle valve will lead to a change of flow rate and velocity control cylinder (vcc).  any variation in the input signal (volt) to 2 way proportional flow control valve (pfcv) type (2fre) will leads to a variation of flow rate and velocity control cylinder (vcc).  the viscosity of hydraulic fluid is independence of the 2-way proportional flow control valve achieved because the form of the metering orifice. the velocity control cylinder (vcc) depends on measuring orifice of the 2-way proportional flow control valve  the measuring orifice can be opened and closed with a delay two ramps in the electronic amplifier for 2way proportional flow control valve (pfcv) type (2fre).  through the use of different measuring orifice, various maximum flow rates can be achieved at 100% input signal value.  the characteristic flow curves progressive depending on the shape of the measuring orifice.  when comparing characteristic flow curves for this work with the manufacturer company of (pfcv) show that there is a difference. the reason for this lies in the additional flow resistances of hoses, pipes and quick release coupling. to ensure is perfect operation of 2-way proportional flow control valve. we must make sure of the following notes;  it is necessary to bleed the solenoid of the 2way proportional flow control valve at the highest point of the valve during initial operation.  under certain installation conditions, the tank line must be prevented from running empty by the installation of a preload valve.  the actuator (cylinder) can be controlled both in meter-out and meter-in modes. 8. references [1] massimo rundo & nicola nervegna (july 2007) “geometry assessment of variable displacement vans pumps” asme vol.129. [2] bilikiz yunus, abdukerim haji (2013) "modeling and analysis of the electrohydraulic proportional pitch control system for the large wind turbine"9th international conference on fracture & strength of solids, june 9-13, jeju, korea. [3] zhang q. & carrol e. goening, (2002) " hydraulic linear actuator velocity control using a feed – forward – plus – pid controller " international journal of flexible automatic and integrated manufacturing (7:275-290). [4] vaughan n.d. & j.b. gamble, (1999) "the modeling and simulation of proportional solenoid valve" asme journal of dynamic systems, measurement and control (118:120125). [5] eko prasetiawan, et al., (2001) " fundamental performance limitations for a class of electronic two-stage proportional flow valves" department of mechanical and industrial engineering university of illinois, urbana-champaign. [6] ming xu et al, (2013) "speed-control of energy regulation based variable-speed electro hydraulic drive" strojniški vestnik journal of mechanical engineering 59(2013)7-8, 433-442. [7] dechrit maneetham, & nitin afzulpurkar, (2010) "modeling, simulation and control of high speed nonlinear hydraulic servo system" journal of automation, mobile robotics & intelligent systems vol. 4, no. 1. [8] richard poley, (january 2005) "dsp control of electro-hydraulic servo actuators" texas instruments application report spraa76 [9] radu-iulian (2012)"theoretical and experimental investigations regarding the dynamic performance of the servo-solenoid 0 1 2 3 4 5 6 0 5 10 15 retraction velocity value of throttle setting r e tr a c ti o n v e lo c it y ( c m /s ) without load with load majid ahmed oleiwi al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 115123(2016) 122 directional valve" u.p.b. sci. bull., series d, vol. 74, issn. 2, issn 1454-2358. [10] arthur akers, et al., (2006) "hydraulic power system analysis" by taylor & francis group, llc. [11] merrit h. e., (1967) "hydraulic control system" wilegand sons. [12] w. kmmetmuller, et al., (feb.2007)"mathematical modeling and nonlinear controller design for a novel electro hydraulic power steering system" ieee/asme trans, on mechatronics, vol. 12 no.1, pp.85-97. [13] rexroth busch group, (2007)"proportional flow control valve, 2-way version" re 29188 [14] r. ewald, et al, (1989) "proportional and servo valve technology" the hydraulic trainer volume (2) re 00 291/12.89 [15] mannesmann rexroth gmbh staff, (1988)"hydraulic & electronic components for proportional and servo systems" [16] mannesmann rexroth gmbh staff, (1988)" hydraulic training for proportional systems" re 00 275/02.88. [17] majid deldar, afshin izadian, (2014) "modeling of a hydraulic wind power transfer utilizing a proportional valve" 10.1109/tia.2014.2354745, ieee transactions on industry applications. [18] tahany w. sadak and ahmed fouly, (2014) "the effect of different designs on performance of a fluid power control system" asme 2014 power conference. [19] liliya salimovna musina1 et al, (2015) "providing cavitations-free operation of hydraulic systems under passing load in hydraulic actuator" modern applied science; vol. 9, no. 4; 2015 issn 19131844 e-issn 1913-1852 published by canadian center of science and education. http://proceedings.asmedigitalcollection.asme.org/solr/searchresults.aspx?author=tahany+w.+sadak&q=tahany+w.+sadak http://proceedings.asmedigitalcollection.asme.org/solr/searchresults.aspx?author=ahmed+fouly&q=ahmed+fouly (2016) 115123، صفحت 2دد، الع12دجلت الخوارزهً الهنذسٍت الوجلم هاجذ احوذ علٍوي 123 تحكن بالتذفق لل تناسبً اسطوانت باستخذام صوام ةاداء سرع للسٍطرة على العولًالتحقق (2fre) بطرٌقٍٍن نوع هاجذ احوذ علٍوي اندبيعت انخكُٕنٕخٍت/ قسى ُْذست انسٍطشة ٔانُظى majidoleiwi@yahoo.com : االنكخشًَٔ انبشٌذ الخالصت انصًبو انخُبسبً بصٕسة عبيت .انكفبءة ٔاألداء ْٕ ححسٍٍ انٍٓذسٔنٍكٍت حطبٍقبث انطبقت فًٔاالحدبِ انعبو فً اَظًت انسٍطشة انٍٓذسٔنٍكٍت انحذٌثت احدبِ اندشٌبٌ ٔانزي ٌحٕل ببسخًشاساشبسة انذخم انًخغٍشة انى اشبسة خشج ٍْذسٔنٍكٍت حُبسبٍت غٍش -انخذفق –ٌسخخذو صًبيبث نهسٍطشة عهى انضغط (.َبعًت)يصحٕبت ببسحدبج ٔيٍ ُْب ( .دائشة انسٍطشة عهى سشعت االاسطٕاَت انٍٓذسٔنٍكٍت ) كزنك انصًبو انخُبسبً يقبٔيت يخغٍشة ضذ ٔيع اندشٌبٌ الي يسخخذو ٍْذسٔنٍكً فًُٕرج انسٍطشةعهى انخذفق ( انًٕضع)اٌ اسخخذاو انصًبو نخغزٌت يشحذة نهسٍطشة عهى انسشعت . انخغٍشاث ببنضغط ٔفقذاٌ انقذسة حخًٍت ٔيٍ انًخعزس اخخُببٓب ٌدب عهٍُب ُْبيٍ (. شٍئٍت)يحكًت ٔكزنك انخغزٌت انًشحذة حكٌٕ نهًشغم غٍش ٔاضحت انًعبنى ٔبذٌٔ ًَٕرج انخذفق انًزكٕس اَفب حصبح انسٍطشة غٍش . يًكٍ فً ْزا انبحث انذائشة انًصًًت ٔانًبٍُت حدٍز انسٍطشة نُب عهى انسشعت . اخخببس عًم انصًبو ٔكٍفٍت اسخخذايّ فً انذٔائش انكٓشٍْٔذسٔنٍكٍت انًصًًت . ٔبًسبعذة حٕحٍذ انصًبو انالسخعً يع انصًبو انخُبسبً نهخحكى ببنخذفق . يع صًبو خبَق دقٍق ٔانًقبسَت بًٍُٓب ببسخخذاو صًبو حُبسبً نهخحكى ببنخذفق كم انصًبيبث انخُبسبٍت ٔكزنك (. نالسطٕاَت)ٌسخطٍع انصًبو انخُبسبً اٌ ٌؤثش عهى احدبِ انحشكت نالعهى ٔانصًبو انخبَق انذقٍق عهى احدبِ انحشكت نالسفم ل انششكت َبسبً نهخحكى ببنخذفق ححصم فٍٓب حخهفٍت ٔانصًبو انًسخخذو فً ْزا انعًم فٍّ حخهفٍت ٔيعذل دقت انخكشاسبًقبدٌش يعٍُت حسخُبط يٍ خذأانصًبو انج .انًصُعت نهصًبو .س انٍٓذسٔنٍكٍت انخُبسبٍتانُخبئح انعًهٍت انًسخُبطت يٍ ْزا انبحث خٍذة ٔيقبٕنت ٔيفٍذة خذا نهًصًًٍٍ ٔانعبيهٍٍ فً حُفٍز حصبيٍى انذٔائ mailto:majidoleiwi@yahoo.comالبريد mailto:majidoleiwi@yahoo.comالبريد mailto:majidoleiwi@yahoo.comالبريد (microsoft word \315\323\355\344 \343\315\343\31712-21) al-khwarizmi engineering journal al-khwarizmi engineering journal,vol. 13, no. 4, p.p. 1221 (2017) best level of parameters for a critical buckling load for circular thin walled structure subjected to bending hussein m. h. al-khafaji department of mechanical engineering/ university of technology/ baghdad email: hussalkhafaji@gmail.com (received 22 february 2017; accepted 2 july 2017) https://doi.org/10.22153/kej.2017.07.003 abstract circular thin walled structures have wide range of applications. this type of structure is generally exposed to different types of loads, but one of the most important types is a buckling. in this work, the phenomena of buckling was studied by using finite element analysis. the circular thin walled structure in this study is constructed from; cylindrical thin shell strengthen by longitudinal stringers, subjected to pure bending in one plane. in addition, taguchi method was used to identify the optimum combination set of parameters for enhancement of the critical buckling load value, as well as to investigate the most effective parameter. the parameters that have been analyzed were; cylinder shell thickness, shape of stiffeners section and the number of stiffeners. furthermore, to verify the contribution of parameters on buckling response, the analysis of variance technique (anova) method was implemented, which gave the contribution weight as percentages. the analysis of results by these two methods showed that the more effective parameter on the critical buckling load was the thickness of cylinder’s shell and the lowest effective was the number of stiffeners the values of parameters that gave the best critical buckling load combination were: 1) the ratio of cylinder’s diameter to thickness of its shell was 133, 2) the ratio of the depth to thickness of stiffeners was1.6, and 3) the number of stiffeners was 12. keywords: buckling, fem, taguchi method, thin walled structure and anova. 1. introduction circular hollow sections thin-walled structure have a wide use in many applications such as; aircraft lightweight aerospace, towers of wind turbines, chimneys, marine structure, and etc...[1]. one of the important phenomena for failure and collapse of this type of structure is the local buckling. this phenomenon caused by presenting of compression and shear forces resulting from applying of one or combined of pure axial compression, torsion, and bending loads. thus, it is desirable to know what are the circumstances that lead to buckle this type of thin-walled structures, what is the best design to reduce or avoid occurring of buckling and how to improve the stability characteristics. many type of strengthening were used to reinforce the thin wall structure with circular cross section, but the most common are the longitudinal (stringers) and circumferential (rings). the following works [2], [3], [4], and [5]; were investigated theoretically and experimentally these two types of stiffening, the analysis included the shape, size and the enhancement of critical buckling stresses with different kinds of load. [6], [7], and [8] investigated the effect of opening and cutout presenting in the circular thin walled structures on the buckling behavior, and how to stiffen these opening. as well as, unstiffened circular thin walled structures were considered in the researches. hussein m. h. al-khafaji al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 1221 (2017) 13 reddy [9] tests unstiffened cylindrical tubes under pure bending experimentally to estimate the relation between the radius to thickness (r/t) and strain, also to observe the modes of deformation. it is observed that a small change in circular cross section to the oval shape, does not causes the ripples initiation which is the first cause of collapse. the author used in test radius to thickness ratio (r/t) range (15-40) with nominal diameter 25mm and 600mm long with two materials aluminum alloy and stainless steel. jiao and others [1] and [10] studied the bending capacity and buckling behavior of stiffened and unstiffened circular-section structures with different diameter to thickness ratio (17-300), subjected to more than one type of loading and supporting. the finite elements method represents one of various theoretical methods applied to study the circular thin wall structure, the researcher khonke and schnobrich [11] used finite element method to analyze the stresses on a circular cylindrical shell, which was reinforced by using eccentrically ribs strengthen longitudinally and peripherally. they prove that the finite element method can be an effective method to simulate the thin walled structure. e. kim and s. kim [12] conducted analysis for buckling to cylindrical shells with diameter to thickness ratio of more than 800, to evaluate the buckling strength, finite element analysis was used. in addition, the researchers in [13],[14],[15], [16] and [17], have used finite element to investigate stability behavior, optimization and design of unstiffened and stiffened circular thin walled structures. khamlichi et al. [18] and [19] showed that there is a further decreasing in the critical stress of compressed circular cylindrical shells with increasing one extra defect, a finite element method was used to model and simulate the problem. the model consists of circular cylindrical shell with two triangular defects, a parametric study (taguchi method) applied to regard the initial geometric influence of these two defects. in this work, a finite element analysis using software ansys was applied to model the effect of geometry and cross section on the linear buckling behavior of circular thin wall structure (ctws). ctws is strengthen with longitudinal stringers. furthermore, the taguchi method was applied to explore the effectiveness of geometrical parameters and their combine sets on the strength of buckling. moreover, the analysis of variance technique (anova) was employed to determine the weight and contribution of each parameters on the critical load of buckling. 2. theory 2.1. buckling and finite element the buckling is a state of structure in which the applied load are large enough to disturb or destroy the stability of structure. the linear buckling analysis predicts the theoretical buckling strength of a structure. it is modeled as an eigenvalue equation [15], [20] and [21]: …(1) where k is stiffness matrix, is stress stiffness matrix, λ is the eigenvalue (load factor) and ψ is the eigenvector of displacements. the solutions for above formula are the eigenvalues and corresponding eigenvectors. the smallest value from the eigenvalues (roots) represents the critical load factor of buckling. if the applied load is f then the critical load will be (λ*f). if the load is only bending, and cross section of structure is symmetric, there will be positive λ (load factors) and other with negative sign but equal in absolute value, therefore, it should be take the critical load factor according to the direction of applied load. 2.2 taguchi genichi taguchi founded the taguchi method in 1949. it is a methodology for getting the relationship between the input process and output of products. it depends on using orthogonal array (oa) with a small number of experiments to acquire the most favorable setting of parameters for process the taguchi method is an useful tool for better design, gathering concept of quality loss function and design of experiment theory. it provides a systematically approach for optimizing the design performance, cost, and quality. this method employs a statistical measurement named as the ratio of the mean (called signal) to the standard deviation (called noise) (s/n), which represents a logarithmic function of wanted output. there are three standard types of s/n ratio; higher the better (hb), lower the better (lb) and nominal the best (nb) [22] and [23]. in this study, the higher critical load of buckling is required, therefore, the higher the better formula is used: ...(2) where: y: is the read data. n: is the number of observations. hussein m. h. al-khafaji al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 1221 (2017) 14 2.3. analysis of variance (anova) analysis of variance (anova) is a powerful statistical technique, which specify the important parameters and demonstrate the percentage contribution of each parameter. in this research, the ratio (s/n) was used for making the decision. the technique of anova is based on the total sum of squared deviations ( which is equal [24] and [22]: …(3) the percentage contribution p could be calculate as: …(4) d.o.f of any parameter(factor) = k-1 total d.o.f = n-1 …(5) …(6) …(7) where: n the number of observation (trails) in the orthogonal array. ni mean s/n ratio for the ith observation. nm mean of all parameters. ssd sum of the squared deviations. k amount of levels for each parameter. p contribution’s percentage. v parameter’s (factor) variance. ve error’s variance. d.o.f degree of freedom. f ftest, which is indicator quality characteristic of process. 3. modeling 3.1 structure modeling the model of the structure consists of cylindrical thin wall (ctws) cantilever beam structure. two plates were mounted at terminal ends of the beam; to prevent ovalization. one of the plate to support the beam (fixed end) and the other at the free end of beam to support the applied load. the dimensions of plates at the fixed end edge and at free end are (560 x 560 x 20) mm and (560 x 560 x 10) mm, respectively, as shown in fig. 1. the length of beam (bay between the two plates at the ends) was designed according to the ratio between plates-spacing ( l ) and radius (r) which is more than [(l / r) > (½)] to reduce the strength gain of beam [2] and [25]. accordingly, (l) and (r) were set as 2000 mm and 200 mm, respectively. the diameter to thickness ratio of ctws (d/t) was taken in different values by changing thickness and keeping diameter constant at (d = 400 mm). the thickness t varies in three values (1, 2, and 3) mm. the structure is strengthened with three different shape and three different numbers of longitudinal stringers. the shape of strangers have been chosen as a rectangular cross section with three different dimensions having the same area to keep the same mass, as shown in fig. 2. these stringers were connected longitudinally along one side (connected rigidly) to the shell of the ctws, and they are not supported at their transversal two ends (the two ends free). fig. 1. the cylindrical thin wall structure fig. 2. the detail of stiffener. hussein m. h. al-khafaji al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 1221 (2017) 15 the chosen parameters for analysis are three, namely: diameter to thickness of the cylindrical shell (d/t), the number of stringer (ns), and the ratio of depth to thickness of stringer (h/ts). each one of these parameters have three levels as shown in table 1. table 1, parameters and levels symbols parameter levels level 1 level 2 level 3 a ns 4 8 12 b h/ts 25 6.25 1.6 c d/t 400 200 133 where the values of fig 2: ns no. of stiffeners h (mm) depth of stringer ( 50, 25,12.5). ts (mm) thickness of stringer (2, 4 , 8). d (mm) diameter of cylinder (400 ). t (mm) thickness of cylinder ( 1, 2 ,3 ). 3.2 finite element modeling the finite element software that used to perform analysis is ansys 16. shell281element was used to create mesh. this element has eight nodes. each node has six degrees of freedom: rotations about the x, y, and z-axes, and translations in the x, y, and z-axes, and is suitable for thin and moderately thick structures [26]. to generate the mesh, the chosen elements size were; 10 mm in the axial, and circumferential directions for ctws. the element size for the end-plates were 28 mm. depending on the dimension of stiffener; the element size for depth ranges from 3 to 5 mm, while in the axial direction is 10 mm. the fixed end of structure is supported by eight point on the end plate to simulate the connection by eight bolts. the load is applied on the free end in the middle of one edge of plate, as shown in the fig 3. fig. 3. finite elements model the steel structure material was implemented, which is considered as a linear isotropic material. table 2 lists the properties of used material. table 2, steel structure material properties 4. result and dissection 4.1 finite element results a linear buckling analysis is performed to calculate the critical load buckling. according to three parameters and three levels its need an orthogonal array l27. thus, twenty-seven value of critical load were found from different combinations of levels and parameters. table 3 shows the levels combinations and the corresponding results of loads buckling. each value of critical buckling load in the fifth column of table 3 is obtained from the calculating of average value for analyzing the finite elements model to three times for each parameters set and corresponding levels (raw in the table). young’s modulus (mp) poisson’s ratio tensile yield strength (mp) tensile ultimate strength (mp) 2x105 0.3 250 460 hussein m. h. al-khafaji al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 1221 (2017) 16 table 3, paramters and resulting critical buckling load no. of tests no. of stiffeners ( ns ) shape of stiffeners ( h/ts ) d/t critical buckling load (mn) 1 4 25 400 34.52 2 8 25 400 37.78 3 12 25 400 40.28 4 4 6.25 400 42.72 5 8 6.25 400 44.78 6 12 6.25 400 49.82 7 4 1.6 400 45.28 8 8 1.6 400 48.55 9 12 1.6 400 50.37 10 4 25 200 76.63 11 8 25 200 77.86 12 12 25 200 80.22 13 4 6.25 200 137.58 14 8 6.25 200 140.79 15 12 6.25 200 159.83 16 4 1.6 200 147.53 17 8 1.6 200 150.01 18 12 1.6 200 161.51 19 4 25 133 113.51 20 8 25 133 115.18 21 12 25 133 118.06 22 4 6.25 133 319.47 23 8 6.25 133 327.52 24 12 6.25 133 334.82 25 4 1.6 133 332.11 26 8 1.6 133 339.27 27 12 1.6 133 343.14 the fig. 4 and fig. 5 shows the variation of load with variation in two parameters and the third one is constant. these figures show that the most effective parameter is the thickness of cylinder especially in the fig. 5, while the less effective parameter is the number of stiffeners; this is attributed to the load, which is applied in one plane (vertical plane) as shown in fig 3. fig. 4. the variation of critical load with parameters at constant d/t hussein m. h. al-khafaji al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 1221 (2017) 17 fig. 5. the variation of critical load with parameters at constant h/ts ratio fig.7 shows samples of local buckling deformation in cylinder shell and stiffeners. the buckling occurs in the side of compression stress due to bending. it could be seen that mode of the buckling where the cylinder’s shell of structure is wrinkled, and the stiffener buckled in sine wave manner. fig. 6. loacal buckling of four stiffneres hussein m. h. al-khafaji al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 1221 (2017) 18 fig.7. (8 and 12) stiffeners with different h/ts. 4.2 .taguchi and anova results the orthogonal array is shown in table 4 , while the results of mean based on s/n were presented in table 5 and fig. 8. table 4, orthogonal array and s/n no. of tests -a sn -b h/ts -c d/t critical buckling load mn s/n 1 4 25 400 34.52 30.761 2 8 25 400 37.78 31.545 3 12 25 400 40.28 32.102 4 4 6.25 400 42.72 32.613 5 8 6.25 400 44.78 33.022 6 12 6.25 400 49.82 33.948 7 4 1.6 400 45.28 33.118 8 8 1.6 400 48.55 33.724 9 12 1.6 400 50.37 34.043 10 4 25 200 76.63 37.688 11 8 25 200 77.86 37.826 12 12 25 200 80.22 38.086 13 4 6.25 200 137.58 42.771 14 8 6.25 200 140.79 42.971 15 12 6.25 200 159.83 44.073 16 4 1.6 200 147.53 43.378 17 8 1.6 200 150.01 43.522 18 12 1.6 200 161.51 44.164 19 4 25 133 113.51 41.101 20 8 25 133 115.18 41.228 21 12 25 133 118.06 41.442 22 4 6.25 133 319.47 50.089 23 8 6.25 133 327.52 50.305 24 12 6.25 133 334.82 50.496 25 4 1.6 133 332.11 50.426 26 8 1.6 133 339.27 50.611 27 12 1.6 133 343.14 50.709 from the table 5 and figure 8 it is seen that the optimum set of levels is (a3 b3 c3) which gives the best critical buckling load. this means that the number of stiffeners is 12 and the (h/ts =1.6) and (d/t =133). delta column represents the difference between the highest and lowest level b12 stiffeners a8 stiffeners hussein m. h. al-khafaji al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 1221 (2017) 19 value. it indicates that the ratio d/t (cylinder thickness) has more effect than the other parameters. table 5, analysis of mean results based on s/n s y m b o ls p a ra m eters l e v el 1 l e v el 2 l e v el 3 d e lta r a n k a ns 40.216 40.528 41.007 0.791 3 b h/ts 36.864 42.254 42.633 5.769 2 c d/t 32.764 41.609 47.379 14.62 1 fig. 8. the parameterss/n curves table 6 shows the results of anova. these results indicate the importance and contribution of parameters as a percentage. the d/t ratio has the highest contribution (80.814%) and the lowest and approximately no effect is number of stiffeners (0.133%). table 6, anova result source sum sq. d.o.f mean sq. f p % a 1.67 2 0.834 0.33 0.133 b 188.45 2 94.225 37.15 15.02 c 1014.21 2 507.10 199.9 80.81 error 50.73 20 2.536 4.042 total 1255 26 5. conclusion this paper has presented the analysis of linear buckling which results from pure bending. in this work, the bending was applied on hollow cylindrical thin walled structure strengthen by longitudinal stiffeners. the finite elements methods used to carry on the analysis. it was shown that the thickness of the cylinder is more effective parameter on the critical buckling load which is followed by the shape of cross section for stiffeners. the results indicated that the number of stiffeners shows approximately no effect to the critical load of buckling. these results approved and conformed by using the taguchi and anova methods. taguchi gaves the weight of parameters and the best-set combination of parameters, while anova showed the percentage of contribution for each parameter. the results demonstrated that taguchi and anova are power full tool to investigate the importance of parameters during the design of structures. 6. references [1] l. guo, s. yang, and h. jiao, “behavior of thin-walled circular hollow section tubes subjected to bending,” thin-walled struct., vol. 73, pp. 281–289, 2013. [2] t. p. peterson, “bending tests of ring stiffened circular cylinders,” 1956. [3] j. singer, “the influence of stiffener geometry and spacing on the buckling of axially compressed cylinderical and conical shells,” technion-israel institute of technology, 1967. [4] n. t. phuong and d. h. bich, “buckling analysis of eccentrically stiffened functionally graded circular cylindrical thin shells under mechanical load,” vol. 29, no. 2, pp. 55–72, 2013. [5] d. huy, d. van dung, v. hoai, and n. thi, “nonlinear static and dynamic buckling analysis of imperfect eccentrically stiffened functionally graded circular cylindrical thin shells under axial compression,” int. j. mech. sci., vol. 74, pp. 190–200, 2013. [6] m. shariati and a. akbarpour, “buckling and post buckling investigation of thin walled shells contain elliptical and circular cutout , subjected to oblique loading,” vol. 2, no. 9, pp. 9548–9557, 2012. [7] c. a. dimopoulos and c. j. gantes, “thinwalled structures experimental investigation of buckling of wind turbine tower cylindrical shells with opening and stiffening under bending,” thin walled struct., vol. 54, pp. 140–155, 2012. hussein m. h. al-khafaji al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 1221 (2017) 20 [8] h. reyno, j. park, and y. kang, “influence of door opening and collar stiffener on the buckling capacity of cylindrical wind tower,” vol. 8, no. october, pp. 1–7, 2015. [9] b. d. reddy, “an experimental study of the plastic buckling of circular cylinders in pure bending,” int. j. solids struct., vol. 12, pp. 669–683, 1979. [10] h. jiao and x. l. zhao, “section slenderness limits of very high strength circular steel tubes in bending,” thin-walled struct., vol. 42, no. 9, pp. 1257–1271, 2004. [11] p. c. khonke and w. c. schnobrich, “a finite element analysis of eccentrically stiffened ciruclar cylindrical shells,” urbana, illinois, 1969. [12] s. e. kim and c. s. kim, “buckling strength of the cylindrical shell and tank subjected to axially compressive loads,” thin-walled struct., vol. 40, no. 4, pp. 329–353, 2002. [13] n. n. thakre and d. v bhope, “investigation of stresses in ring stiffened circular cylinder,” no. 9, pp. 97–101, 2014. [14] a. t. tran, m. veljkovic, and c. rebelo, “buckling observation of door openings for wind turbine towers,” no. september, pp. 4–11, 2015. [15] v. polenta, s. d. garvey, d. chronopoulos, a. c. long, and h. p. morvan, “optimal internal pressurisation of cylindrical shells for maximising their critical bending load,” thin-walled struct., vol. 87, pp. 133–138, 2015. [16] l. gangadhar and t. s. kumar, “finite element buckling analysis of composite cylindrical shell with cutouts subjected to axial compression,” vol. 89, pp. 45–52, 2016. [17] o. lykhachova, “numerical simulation of axially compressed cylindrical shells with circular cutouts,” vol. 20, no. 3, pp. 309– 320, 2016. [18] a. khamlichi, j. el bahaoui, l. el bakkali, m. bezzazi, and a. limam, “effect of two interacting localized defects on the critical load for thin cylindrical shells under axial compression,” am. j. eng. appl. sci., vol. 3, no. 2, pp. 464–469, 2010. [19] a. khamlichi and a. limam, “assessing the effect of two entering triangular initial geometric imperfections on the buckling strength of an axisymmetric shell subjected to uniform axial compression,” in proceedings of the eleventh international conference on computational sructures technology, 2012, pp. 1–11. [20] r. d. cook, finite element modeling for stress analysis. new york: john willy and sons, inc., 1995. [21] a. h. suri, “a study of structure stability using the finite element method and minimum weight design of composite panel,” university of glasgow, 1983. [22] m. s. phadke, “quality engineering using robust design.” p t r pentice hall, englewood cliffs, new jersey, 1989. [23] j. lin and k. lee, “optimization of bending process parameters for seamless tubes using taguchi method and finite element method,” adv. mater. eng., vol. 2015, 2015. [24] rupert g. miller, “beyond anova, basics of applied statistics.” john wiley & sons, inc., canada, 1986. [25] l. jiang, y. wang, and x. wang, “buckling analysis of stiffened circular cylindrical panels using differential quadrature element method,” thin-walled struct., vol. 46, no. 4, pp. 390–398, 2008. )2017( 12-21، صفحة 4، العدد13دجلة الخوارزمي الهندسية المجلم حسين محمد حسين 21 ة االلتواء الحرج لهيكل رقيق الجدران دائري معرض لالنحناءحمولل المستوى االفضل حسين محمد حسين الخفاجي بغداد /قسم الهندسة الميكانيكية / الجامعة التكنولوجية hussalkhafaji@gmail.comالبريد االلكتروني : الخالصة يتعرض عادة ألنواع مختلفة من االحمال، ولكن واحدة من اهم نوع هو حمل الهياكل الرقيقة الجدران االسطوانية لها تطبيقات واسعة. هذا النوع راسة مركب من: االنبعاج. في هذا العمل، تم دراسة ظاهرة االنبعاج باستخدام التحليل بالعناصر المحددة، الهيكل الرقيق الجدران االسطواني في هذه الد بأضالع تقوية طولية معرض فقط الى انحناء في مستوي واحد. المتغيرات التي تم تحليلها هي سمك قشرة األسطوانة، شكل أسطوانة ذات جدرن رقيقة مقواه كذلك للتحقق مقطع اضالع التقوية وعدد اضالع التقوية. طريقة تاكوجي استخدمت لتحديد أفضل تركيب من المتغيرات لتحسين قيمة الحمل الحرج لالنبعاج و .مئويةيرات أكثر فاعلية. ألثبات مساهمة المتغيرات على استجابة االنبعاج تم تطبيق طريقة التحليل المتباين والتي تعطي وزن المساهمة كنسبة أي من المتغ الية هو عدد اضالع األكثر فعالية على حمل االنبعاج الحرج كانت سمك قشرة االسطوانة وأدنى فع أن المتغيرهاتين الطريقتين باستخدامأظهر تحليل النتائج )، نسبة العمق إلى سمك 133هي ( قشرتهاهي: نسبة قطر األسطوانة إلى سمك حرج وكانت قيم المتغيرات التي تعطي تركيب ألفضل حمل انبعاج التقوية. ).12( هي ) ألضالع التقوية، وعدد التقوية1.6(هي الطبقة artificial neural networks (anns) are a form of artificial intelligence, which have proven useful in different areas of application, such as pattern recognition [1] and function approximation/ prediction [2] ammar a. hassan /al-khwarizmi engineering journal ,vol.2, no. 2 pp 32-41 (2006) 23 low cost hardware back propagation algorithm ammar a. hassan computer engineering department / college of engineering university of baghdad (received 14 november 2005; accepted 4 april 2006) abstract: the first successful implementation of artificial neural networks (anns) was published a little over a decade ago. it is time to review the progress that has been made in this research area. this paper provides taxonomy for classifying field programmable gate arrays (fpgas) implementation of anns. different implementation techniques and design issues are discussed, such as obtaining a suitable activation function and numerical truncation technique trade-off, the improvement of the learning algorithm to reduce the cost of neuron and in result the total cost and the total speed of the complete ann. finally, the implementation of a complete very fast circuit for the pattern of english digit numbers nn has four layers of 70 nodes (neurons) on single chip using xilinx fpga technique is given. the main goal of this paper is how to achieve the suitable activation function and weights for this network that gives minimum hardware cost when all stages of this ann algorithm is implemented on fpga. 1.introduction artificial neural networks (anns) are a form of artificial intelligence, which have proven useful in different areas of application, such as pattern recognition [1] and function approximation/ prediction [2]. the most popular neural network is the multi-layer perceptron trained using the error back propagation algorithm [3]. however, an important obstacle in using this network in many applications is the slow training and the lack of clear methodology to determine the network topology before training starts. it is then desirable to speedup the training and allow fast experimentation with various topologies. one possible solution is an implementation on a reconfigurable computing platform (e.g field programmable gate arrays) fpga. reconfigurable computing is a means of increasing the processing density (i.e. greater performance per unit of silicon area) above and beyond that provided by general-purpose computing platform [4]. field programmable gate arrays (fpgas) are a medium that can be used for reconfigurable computing, since they allow for custom design of fine-grain logic compared to course-grain logic found in general-purpose computing platforms. fpgas are a form of programmable logic, which offer flexibility in design like software, but with performance speeds closer to application specific integrated circuits (asics). with the ability to be reconfigured an endless amount of al-khwarizmi engineering journal al-khwarizmi engineering journal, vol.2,no.2,pp 32-41 (2006) ammar a. hassan /al-khwarizmi engineering journal ,vol.2, no. 2 pp 32-41 (2006) 22 times after it has already been manufactured, fpgas have traditionally been used as a prototyping tool for hardware designers. however, as growing die capacities of fpgas have increased over the years, so has their use in reconfigurable computing applications too [2, 4]. 2.problem formulation the design problem in ann using fpga is a precision vs. area trade-off. one way to help achieve the density advantage of reconfigurable computing over general-purpose computing is to make the most efficient use of the hardware area available. in terms of an optimal precision vs area trade-off, this can be achieved by determining the minimum allowable precision, whose criterion is to minimize hardware area usage without sacrificing quality of performance. because a reduction in precision introduces more error into the system, minimum allowable precision is actually a question of determining the maximum amount of uncertainty (i.e. quantization error due to limited precision) that an application can withstand before performance begins to degrade. hence, determining a minimum allowable precision and suitable numeric representation to use in hardware is often dependent upon the application at hand, and the algorithm used. fortunately, suitable precision for backpropagation-based anns has already been empirically determined in the past. selecting weight precision is one of the important choices when implementing anns on fpgas. weight precision is used to tradeoff the capabilities of the realized anns against the implementation cost. a higher weight precision means fewer quantization errors in the final implementations, while a lower precision leads to simpler designs, greater speed and reductions in area requirements and power consumption. one way of resolving the tradeoff is to determine the “minimum precision”, required to solve a given problem. traditionally, the minimum precision is found through “trial and error” by simulating the solution in software before implementation. holt and baker [5] studied the minimum precision required for a class of benchmark classification problems and found that 16-bit fixed-point is the minimum allowable precision without diminishing an ann’s capability to learn these benchmark problems. 3.ann example 3.1.structure of the circuit following example [6] present how these two parameters effect on hardware resources. remember that in neural network resources capacity differ from network to other according to number of neurons in each layer. the existence of hidden units allows the network to develop complex feature detectors, or internal representations. fig.(1) shows the application of four layers network to the problem of recognizing english digit numbers. the two dimensional grid containing the numeral “7” forms the input layer (it can be arranged this two dimension array as one dimension, so that, number of input neurons is thirteen). ammar a. hassan /al-khwarizmi engineering journal ,vol.2, no. 2 pp 32-41 (2006) 23 the first hidden layer is formed from 40 units each unit might be strongly activated by horizontal line in the input, while the second hidden layer molded from 20 hidden units, each unit fully connected with each unit in the first hidden layer. the output layer has ten units that represent the value of the digit number. knowing that, the behavior of these hidden units is automatically learned not preprogrammed, then the computing weight of each layer in the network accuracy by using c++ programming language and implementing this result on fpga as shown in the next section. 3.2.implementation ann components on fpga digital ann architecture proposed in the previous section is an example of a reconfigurable computing application, where all stages of the algorithm reside together on the fpga at once. these components based in idea of implementation on simple (or basic) arithmetic operations (such as addition and multiplication operations). the floating-point precision is the problem of which an engineer must deal with when testing and validating circuits since it limits quantization errors according to number of bits in each node. therefore, truncation technique will be used in design to reduce the floating-point precision value and employ minimum hardware resources available on fpga. adding to this, choosing the optimal activation function suitable for implementation with truncation technique. previously as declared, the ann algorithm components (such as number of hidden layers and number of units in each fig.(1): multilayer network to learn to classify english numbers 0 1 2 3 4 5 6 7 8 9 output 10 nodes hidden2 20 nodes input 25 nodes hidden1 40 nodes ammar a. hassan /al-khwarizmi engineering journal ,vol.2, no. 2 pp 32-41 (2006) 23 layer) differ from application to another. the english digit numbers nn is the application used in this work to implement ann on fpga, which is composed from four layers. the quantization error after 5,000 iteration using two types of activation functions are given in table (1). by using sigmoid function and without truncation (30-bit floating-point), quntization error is 0.02 (i.e. 98% of the corrected output). while, by the same method, but using bipolar function instead of sigmoid function, quntization error will be given 0.04. 4.arithmetic architecture for fpga based anns to calculate the cost required for english digit number nn in fpga, it should be declared the way of selecting activation function against truncation approach as following: 4.1.sigmoid function without truncation (30-bit) before calculating the cost of fpga based digit nn, it should be known that this function produced floating-point values. then, it required a large number of logic storage as basic logic cells (lcs) called lookuptables (luts). these lcs are formed as ram to store the output value of this function in each unit in the nn algorithm. for 30-bit flotation-point, ram cost implementation in fpga 30-bit input and 30bit output, for each unit in nn algorithm. then, when sigmoid function applied in algorithm design is increased number of lcs, so that, it increased the over all hardware resources of nn algorithm. the average cost of each unit (node) is calculated according to equation (1).   **/ nnunitcost (1) where, n = number of bits in data bus. α = cost for each multiplier in fpga. β = cost for each adder / subtractor in fpga. δ = cost for each lut in fpga for sigmoid function. ifor n=30 bit with sigmoid function α is a (30*30)-bit multiplier and require about (2250) cell. β is a 30-bit adder / subtractor and require about (225) cell. finally δ requires about (125000) cell using cordic approach. so that, the cost of arithmetic components / unit (for 30-bit sigmoid)  200,000 cell. therefore for english digit nn algorithm from previously, there are seventy units then: total cost (for english digit nn) = 200,000 * 70 = 14,000,000 cell. this process can be achieved approximately by 17 of propagation gates delay. activation function quantization error without truncation (30-bit) direct truncation after learning (10-bit) sigmoid bipolar 2% 4% 13-19% 18-26% table (1): quntization error with and without truncation ammar a. hassan /al-khwarizmi engineering journal ,vol.2, no. 2 pp 32-41 (2006) 23 iiwhen applying truncation technique through the learning process with sigmoid function on ann, the unit output precision reduces to be 10-bit and using equation (1). total cost / unit  4000 cell. where n = 10-bit, α = 300 cell, β = 75 cell, and δ = 60 cell. total cost (for english digit nn) = 4000 * 70 = 280,000 cell with over all propagation delay reduced to 7 propagation gates delay. from this result, when applying this technique in nn algorithm design it can reduce number of luts on fpga and so reduce the over all hardware resources capacity. 4.2.bipolar function as demonstrated from previous section, it required a large number of cells to implement nn based on sigmoid function. then, bipolar function instead of sigmoid function in a nn algorithm can be used. where, this function does not need storage cells for the output values in luts, because the output from this function is either “-1” or “1”, this technique called multiplierless technique. this approach has α =1 cell and δ=0 cell therefore, the cost for each unit in a nn algorithm based bipolar function calculated using equation (2). */ nnunitcost  (2) n = number of bits in data bus. β = cost for each adder / subtractor in fpga. iwithout truncation technique (i.e. n=30-bit ) β = 215 cell, therefor the cost / unit  6,500 cell. this process exceeds in 17 propagation gates delay. then, to implement the english digit nn, that included 70 active neurons the total cost  455,000 cell. iiwith truncation technique (i.e. n=10-bit ) β = 64 cell, therefor the cost / unit = 650 cell. also, this process exceeds in 7 propagation gates delay. so that, to implement the english digit nn that included 70 neurons the total cost  45,500 cell. then, the total luts cost of nn can be reduced when applying bipolar function with truncation technique on fpgas. 5.proposed backpropagation algorithm [5] an ann using the classic backpropagation algorithm [6] as in fig.(2) has three basic phases named (1, 2 and 3) of execution the proposed backpropagation algorithm has same structure of the classic backpropagation algorithm with three additional steps for the proposed backpropagation algorithm named (1a, 2a and 3a) as following: ammar a. hassan /al-khwarizmi engineering journal ,vol.2, no. 2 pp 32-41 (2006) 23 fig. (2): generic structure of an ann. 5.1.initialization the following initial parameters have to be determined by the ann trainer a priori: (i) )()( nw s kj is defined as the synaptic weight that corresponds to the connection from neuron unit j in the (s-1) th layer, to k in the s th layer of the neural network. (ii)  is defined as the learning rate and is a constant scaling factor. (iii) )(s k is defined as the bias of a neuron, which is similar to synaptic weight in that it corresponds to a connection to neuron unit k in the (s-1)th layer of the ann ,but is not connected to any neuron unit j in the(s-1) th layer. (1a) set counter =0 5.2.forward computation during the forward computation, data from neurons of a lower layer (i.e (s-1) th layer), are propagated forward to neurons in the upper layer (i.e. (s) th layer) via a feedforward connection network. the structure of such a neural network is shown in figure 2, where layers are numbered 0 to m, and neurons are numbered 1 to n. the computation performed by each neuron (in the hidden layer) is as follows: θowh (s) k )(sj s-n j (s) kj (s) k    1 )1( 1 (3) where j < k and s=1,….,m )1(s-n = number of neurons in the (s-1)th layer of the ann. )(s kh = weight sum of the k th neuron in the sth layer. )(s kjw = synaptic weight which corresponds to the connection from neuron unit j in the (s-1) th layer to neuron unit k in the s th layer of the neural network )1( s jo output of the jth neuron in the (s-1) th layer. on the other hand, the output computation of neurons in any layer is as follows: ) f ( ho (s) k (s) k  (4) where k =1,…,n and s= 1,…,m o s k )( = neuron output of the kth neuron in the sth layer. ) f ( h (s) k = activation function computed on the weighted sum h (s) k . ammar a. hassan /al-khwarizmi engineering journal ,vol.2, no. 2 pp 32-41 (2006) 23 note that some sort of sigmoid function is often used as the nonlinear activation function, such as the following logsig function as in equation (5) or bipoler as in equation (6) as follows: (-x) sig f(x) exp1 1 log   (5)       01 01 or x f for x bipoler f(x) (6) (2a) increment counter for cycle counter = counter +1. 5.3.backward computation in this step, the weights of the networks are updated. criterion for the learning algorithm is to minimize the error between the expected (or teacher) value and the actual output value that was determined in the forward computation. the following steps are performed: istarting with the output layer, and moving back towards the input layer, calculate the local gradients, as follows:             )1( 1 11 11 sn j )(s j s kj (s) kk (s) k ,...,m s ms δw ot ε (7) tk = the target output for kth neuron in the m layer. )1( sn = number of neurons in the (s+1)th layer of the ann. where  )(s k = error term for the kth neurons in the sth layer. the difference between the teaching signal b _ and the neuron output )(s ko )1( s j = local gradient for the j th neuron in the (s+1)th layer. ,....,m s) ( hfεδ (s) k \(s) k (s) k 1 (8) iiusing the local gradients calculated in step 1, calculate the weight (and bias) changes for all the weights as follows: noδw s)(s j (s) k (s) kj ,..., and j,....,ns k η δ 1 1 11   (9) where w (s) kj δ is the change in synaptic weight (or bias) corresponding to the gradient of error for connection from neuron unit j in the (s+1) th layer, to neuron k in the s th layer. iiionce all weight (and bias) changes have been calculated in step 2, update all the weights (and biases) as follows: (n) (n) δ) (n www s kj s kj s kj 1 (10) where k = 1,….., n neurons in the s th layer and j = 1,………, n neurons in the (s-1) th layer. )1()( nw s kj = update synaptic weight (or bias) to be used in the (n+1) th iteration of the forward computation. )()( nw s kj = change in synaptic weight (or bias) calculated in the n th iteration of the backward computation, where n =the current iteration. ammar a. hassan /al-khwarizmi engineering journal ,vol.2, no. 2 pp 32-41 (2006) 23 )()( nw s kj = synaptic weight (or bias) to be used in the n th iteration of the forward and backward computations, where n = the current iteration. (3a) truncation for each counter > q makes a truncation as in equation (11) to the values of the weights )()( nw s kj . ) -) * (/ (n) int (w(n)w nn(s) kj (s) kj 122 (11) where q is a small integer value depends on the ann, it defaults between 5to50. n:number of bits in data bus. for truncation in the range of 10-bit this equation becomes as in equation (12). 10231024 ) * / (n) int (w(n)w (s) kj (s) kj  (12) 6.comparative study the simple example is the four-layer network to the problem of recognizing english digit numbers that has 70 nodes. the implementation of this nn using ise 4.1i on xilinx platform [7, 8] shows the effect of the proposed algorithm on the total cost and the final error as in table (2). 7.conclusion generally, any complete circuit of ann has a very high cost because the high resolution of the weight values required is about 30-bit or more. the truncation of this data to low number such as 10-bit will reduce the total cost to 5% from the total cost but increase the error to more than 10 times. in addition to this, the effect of the transfer function type such as sigmoid or bipolar function declared the cost of the classic nn, where sigmoid function is 30 times over the bipolar transfer function but the bipolar has in average twice the error. this work has shown capability choice of different transfer functions for nn algorithm that are suitable to reduce the hardware cost with an optimal choice of precision value, by applying proposed truncation algorithm to reduced precision value from 30-bit to 10-bit with minimum possible error. the matching of the proposed algorithm with bipolar transfer function will reduce the cost to 0.3% from the total cost and increases activation function number of bits algorithm final error % total nn cost / cell max speed of nn / mhz sigmoid 30 classic 2 14,000,000 35 bipolar 30 classic 4 455,000 35 sigmoid 10 classic with truncation 16 280,000 74 bipolar 10 classic with truncation 22 45,500 74 sigmoid 10 proposed 6 455,000 74 bipolar 10 proposed 9 45,500 74 table (2): quntization error, cost and the maximum speed of nn with and without truncation. ammar a. hassan /al-khwarizmi engineering journal ,vol.2, no. 2 pp 32-41 (2006) 34 the speed to twice the original speed but increase the error from 2% to 10%. while, the direct truncation with classic learning algorithm with bipolar transfer function will give a very high error reaching to 25% while the truncation using the proposed learning algorithm with bipolar transfer function will reduce the error to less than 10% with the same cost and same speed. 8.references [1] m. skrbek, “fast neural network implementation”, neural network world, vol. vol. 9, n. no. 5, pp. 375–391, 1999. [2] j. g. eldredge, “fpga density enhancement of a neural network through run-time reconfiguration”, master’s thesis, department of electrical and computer engineering, brigham young university, may 1994. [3] d.e rumelhart, j.l mcclelland and pdp research group, parallel distrubuted processing: explorations in the microstructure of cognition, volume 1: foundations, mit press, cambridge, massachusetts, 1986. [4] a. dehon, “the density advantage of configurable computing”, ieee computer, vol. 33, n. 5, pp. 41–49, april 2000. [5] holt, j.l., t.e. baker. back propagation simulations using limited precision calculations, in proceedings of international joint conference on neural networks. 1991. pp 121-126 vol. 2. [6] e. k. knight, “artificial intellingence” mcgraw-hill new york, second edition, 1991. [7] xilinx.com, “virtextm2.5v fpgas”, data sheet, www.xilinx.com, may 1999. [8] wolf, d.f., romero, r. a. f., marques, e. using embedded processors in hardware models of artificial neural networks. in proceedings of sbai simp َ sio brasileiro de automao inteligente. 2001. pp 78-83. 9.list of symbols ann: artificial neural network. asic: specific integrated circuit. cordic: coordinate rotation digital computer. fpga: field programmable gate array. lc: logic cell. lut: lookuptable. ram: random access memory. ammar a. hassan /al-khwarizmi engineering journal ,vol.2, no. 2 pp 32-41 (2006) 34 بناء مستوى واطئ الكلّفة لخوارزمية االنتشار العكسي عمار عادل حسن لهــندسـة/ كــلية اقـسم هـندسة الحـاسبـات جامـعة بغـداد الخالصة: ( كانت قليلة وقبل أكثر من annsمن أولى التطبيقات الناجحة التي تم نشُرها للشبكات العصبية االصطناعية ) جال هذا النوع من البحوث. يمتاز هذا الملخص بتوفير الفكرة عقد. لذلك حان الوقت لمراجعة التقّدم الذي تم في م لبناء (fpgas)األساسية حول تطبيق أصناف األنواع المتوفرة للبوابات المرتبة بصيغة صفوف قابلة للبرمجة الشبكات العصبية االصطناعية. تقنيات مختلفة التطبيق وأفكار للتصميم سيتم مناقشتها الحقاً, مثالً الحصول على الدالة الفاعلة والمناسبة وتقنية التقليم العددية. كذلك, العمل على تحسين خوارزمية التعلم للتقليل من كلفة بناء الكلية وتحسين أداء الشبكة العصبية. وأخيراً, بناء دائرة متكاملة لها الخلية العصبية وبالتالي تقليل الكلفة 07السرعة العالية لتميز أشكال األرقام اإلنكليزية من خالل شبكة عصبية اصطناعية لها أربعة طبقات من خالل ) . xilinx fpga( عقدة )خلية عصبية( على رقاقة واحدة باستخدام تقنية 26-35 al-khwarizmi engineering journal,vol. path planning of an autonomous bacterial foraging optimization nizar hadi *,**department of electrical (received http://dx.doi.org/10.22153/kej.2016.01.001 abstract this paper describes the problem of online autonomous mobile robot path planning, which is consisted of finding optimal paths or trajectories for an autonomous mobile robot from a starting point to a destination across a flat map of a terrain, represented by a 2-d workspace. a bacterial foraging optimization algorithm is presented. this the foraging behavior of e-coli bacteria proposed algorithm was demonstrated by study was evaluated between the developed algorithm and other two state the proposed method is effective and produces trajectories with satisfactory results keywords: autonomous mobile robot, optimization algorithm. 1. introduction the field robot path planning was launched at the middle of the 1960s. robot path planning is an important problem in navigation of mobile robots. the aim is to find an optimal and collision path from a predefined start position to a target point in a given environment. generally, there are many paths for robot to reach the target, but in fact, the best path is selected according to some guideline. these guidelines are: shortest distance, least energy consuming or shortest time with the shortest distance is the most adopted criteria [1]. path planning can be seen as an optimization problem since its purpose is to search for a path with shortest distance under certain constraints such as the given environment with motion [2]. in the past several decades, research on optimization algorithms has covered a wide area of researchers' attention. optimization methods and algorithms can be classified in many arizmi engineering journal,vol. 12, no. 4, p.p. 2635 (2016) path planning of an autonomous mobile robot using enhanced bacterial foraging optimization algorithm adi abbas* farah mahdi ali ** electrical engineering/ college of engineering/ university of baghdad *email: drnizaralmsaodi@gmail.com **email: farah95m@yahoo.com (received 20 september 2015; accepted 31 january 2016) http://dx.doi.org/10.22153/kej.2016.01.001 the problem of online autonomous mobile robot path planning, which is consisted of finding optimal paths or trajectories for an autonomous mobile robot from a starting point to a destination across a flat map of a d workspace. an enhanced algorithm for solving the problem of path planning using bacterial foraging optimization algorithm is presented. this nature-inspired metaheuristic algorithm, which imitates coli bacteria, was used to find the optimal path from a starting point to a target point. the demonstrated by simulations in both static and dynamic different environments. a com study was evaluated between the developed algorithm and other two state-of-the-art algorithms. this study showed that the proposed method is effective and produces trajectories with satisfactory results. autonomous mobile robot, path planning, static and dynamic environments, bacterial foraging the field robot path planning was launched at the middle of the 1960s. robot path planning is an important problem in navigation of mobile robots. the aim is to find an optimal and collision-free path from a predefined start position to a target given environment. generally, there are many paths for robot to reach the target, but in fact, the best path is selected according to some guideline. these guidelines are: shortest distance, least energy consuming or shortest time with the ce is the most adopted criteria [1]. path planning can be seen as an optimization problem since its purpose is to search for a path under certain constraints such as the given environment with collision-free everal decades, research on optimization algorithms has covered a wide area of researchers' attention. optimization methods and algorithms can be classified in many types, but the simplest way is to look at the nature of the algorithm, and this grouped the deterministic and stochastic [3, 4] where deterministic techniques depend on the mathematical nature of the problem, while stochastic techniques do not depend on the mathematical properties of a given function and are hence more appropriate for find optimal solutions for any type of objective function. however, the weaknesses of first technique are its dependence on gradient, local optima and inefficient in large and cannot solve discrete functions. stochastic techniques are considered to be more users friendly. as many real problems become increasingly complex, using stochastic methods is inevitable. these algorithms have been found to perform better than the classical or gradient-based methods, esp optimizing the non-diff and discrete complex functions. some e al-khwarizmi engineering journal (2016) mobile robot using enhanced algorithm ** / college of engineering/ university of baghdad the problem of online autonomous mobile robot path planning, which is consisted of finding optimal paths or trajectories for an autonomous mobile robot from a starting point to a destination across a flat map of a n enhanced algorithm for solving the problem of path planning using inspired metaheuristic algorithm, which imitates path from a starting point to a target point. the simulations in both static and dynamic different environments. a comparative hms. this study showed that path planning, static and dynamic environments, bacterial foraging types, but the simplest way is to look at the nature of the algorithm, and this grouped them into deterministic and stochastic [3, 4] where deterministic techniques depend on the mathematical nature of the problem, while stochastic techniques do not depend on the mathematical properties of a given function and are hence more appropriate for finding the global optimal solutions for any type of objective function. however, the weaknesses of first technique are its dependence on gradient, local cient in large-scale search space and cannot solve discrete functions. stochastic ues are considered to be more users friendly. as many real-world optimization problems become increasingly complex, using stochastic methods is inevitable. these algorithms have been found to perform better than the based methods, especially for fferentiable, multimodal, and discrete complex functions. some effective nizar hadi abbas al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 2635(2016) 27 stochastic techniques that mimic the behaviors of certain animals or insects (birds, ants, bees, flies and even germs!) and called nature-inspired algorithms have been developed since 1980s. currently, these nature-inspired paradigms have already come to be widely used in many areas in engineering fields [5, 6]. some of these algorithms are particle swarm optimization (pso) [7], ant colony optimization (aco) [8], artificial bee colony (abc) [9] and bacteria foraging optimization (bfo) [10]. the bacteria foraging optimization (bfo) optimization is one of the most-recent population based (swarm intelligence based) meta-heuristic algorithms, which simulate the foraging behavior of ecoli colonies. it proposed by k. m. passino [10] in 2002.bfo is a simple but powerfulbioinspired optimization technique uses the analogy of swarming principles and social behavior in nature swarm intelligence and it have been adopted to solve a variety of engineering and mobile robotics problems, including path planning problem [11]. in this paper, an enhanced version of the bfo algorithm called adaptive tumble bfo (atbfo) is proposed. a method for recording the best positions achieved by the bacteria so far and saving those directions as a guide to better potential candidate solutions is proposed. the rest of this paper is organized as follows: section 2 describes path planning and problem formulation; section 3 describes the standard bfo algorithm; section 4 describes the proposed atbfo algorithm; section 5 explains robot path planning using atbfo, and the simulation results are shown in section 6. finally, section 7 presents the conclusion of the paper. 2. path planning and problem formulation robot path planning (rpp) is one of the important aspects in robot navigation research. depending on the environment where the robot located in; rpp can be classified into two types: 1) rpp in static environment which has fixed obstacles. 2) rpp in dynamic environment which has both fixed and moving obstacles. each of these two types could be further subdivided into a sub-group: 1) global path planning (gpp): if the knowledge of the environment is known, the global path can be planned offline before the robot starts to moves. 2) local path planning (lpp): is usually constructed online when the robot avoids the obstacles in a real time environment [12]. in this paper, local path planning is adopted where the environment is totally unknown. constructing a model for the environment is important issue; an appropriate representation of the terrain is needed to generate a sufficiently complete map of the given surroundings that the robot will encounter along its route. the mobile robot is defined as a point object in the 2-d space. since the robot reduced to a point each obstacle must be inflated by the size of the robot’s radius to compensate. each obstacle can be represented by polygon surrounded by a circle. obstacles are finite in size and do not overlap and have a safety zone which is the region around the obstacle that the mobile robot must avoid. as the obstacle is of an irregular shape, the radius must be one-half of the longest side of the obstacle plus the robot's radius. 3. standard bfo algorithm bacteria foraging optimization (bfo) algorithm invented by k. m. passino [10] is a relatively new population-based algorithm; it is a nature-inspired metaheuristic algorithm, which imitates the foraging behavior of e. coli. an e. coli bacterium can move in two different ways; it can run (swim for a period of time), or it can tumble, and it alternates between these two modes of operation through its entire lifetime. by tumbling and running, the bacteria will search for nutrient area and keep away from the poisonous area, as shown in fig. 1. fig. 1. chemotactic behavior of e. coli: run and tumble 3.1. chemotaxis chemotaxis is the main motivation of the bacteria’s foraging process. it consists of a tumble nizar hadi abbas al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 2635(2016) 28 with several runs as shown in fig. 1. in bfo, the position updating, which simulates the chemotaxis procedure is used in eq. (1). θ��represents the position of the ith bacterium in the jth chemotaxis step, c i is the step length during the jith chemotaxis and∅ i is a unit vector which stands for the swimming direction after a tumble. it can be generated by eq. (2), where ∆� is a randomly produced vector with the same dimension of the problem: ���� = �� + � � . ∅ � … 1 ∅ � = ∆� �∆��∆� … 2 in each chemotactic step, the bacterium generated a tumble direction firstly. then the bacterium moves in the direction using eq. (1). if the nutrient concentration in the new position is higher than the last position, it will run one more step in the same direction. this procedure continues until the nutrient get worse or the maximum run step is reached. the maximum run step is controlled by a parameter called��. 3.2. reproduction for every �� time of chemotactic steps, a reproduction step is taken in the bacteria population. the bacteria are sorted in descending order by their nutrient obtained in the previous chemotactic processes. bacteria in the first half of the population are regarded as having obtained sufficient nutrients so that they will reproduce. each of them splits into two (duplicate one copy in the same location). bacteria in the residual half of the population die, and they are removed out from the population. the population size remains the same after this procedure. reproduction is the simulation of the natural reproduction phenomenon. by this operation, individuals with higher nutrient are survived and duplicated, which guarantees that the potential optimal areas are searched more carefully. 3.3. elimination and dispersal in nature, the changes of environment where population lives may affect the behaviors of the population. for example, the sudden change of temperature, nutrient concentration and the flow of water. all these may cause bacteria in the population to die or move to another place. to simulate this phenomenon, eliminate-dispersal is added in the bfo algorithm. after every nre time of reproduction steps, an eliminate-dispersal event happens. for each bacterium, a random number is generated between 0 and 1. if the random number is less than a predetermined parameter, known as"#, the bacterium will be eliminated, and a new bacterium is generated in the environment. the operator can be also regarded as moving the bacterium to a randomly produced position. the eliminate-dispersal events may destroy the chemotactic progress. however, they may also promote the solutions since dispersal might place the bacteria in better positions [13]. over all, contrary to the reproduction, this operator enhances the diversity of the algorithm. in bfo algorithm, the eliminate-dispersal events happen for �#$times. 4. adaptive tumble bfo (atbfo) algorithm bfo possesses a poor convergence behavior over complex optimization problems. subsequently, a method for speed up the searching process is needed. the tumble angles (∆i) in the chemotactic phase are generated randomly. as a result, the algorithm is more like a random searching algorithm except it will try in better directions[14]. a method for recording the best positions achieved by the bacteria so far and saving those directions as a guide to better potential candidate areas is proposed. firstly, tumble angles are generated randomly, then each bacterium counts its health improvement if it is larger than predefine constant parameter (f�&'()*), it will save this tumble angle as an input to the next reproduction in the foraging process. that is, the bacterial join resources uncovered by other bacteria in previous chemotactic step. afterwards, they start exploiting the neighborhood of these current positions until the needed criterion (i.e., the feedback from the search process) is reached. the saved tumble angles would help each bacterium for evaluate more precise solutions. the pseudo code of atbfo algorithm is given in pseudo code 1. where s is the colony size, i is the bacterium’s id counter from 1 to s, xi is the ith bacterium’s position of the colony, �� is the maximum number of steps for a single activity of swim, �,-./012 is a counter to determine the fitness improvement for the bacteria positions, f�&'()* is a user defined threshold of the improvement count required, ∆�3�4�56 is the initial directions that generated randomly and ∆�� , ∆���� nizar hadi abbas al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 2635(2016) 29 are current and next saved tumble angles respectively. algorithm 1: adaptive tumble bacterial foraging optimization algorithm step 1: initialize parameters 89: , 8;9 , 8<, 8=, >?and ∆?@?a?bc= ;b@: d step 2: ife < gh, i = i + j. for each bacterium, do the following processes: tumble: generating a random direction using eq. (2) then make a move by eq. (1) and calculate the fitness value at current position. run: whenk < gl,k = k + j.. calculating the fitness value. if better than last step, keep running until k = gl, mknhopqr = mknhopqr +j otherwise go to step 3. step 3: ifmknhopqr > tmknuov, ∆mi�j= ∆mi otherwise ∆mi�j= ∆mqmrmwxi. step 4: ify < guz, [ = [ + j, start reproduction go to step 2, otherwise go to step 5. step 5: ifc < gz\, x = x + j, start eliminationdispersal step go to step 2, otherwise end. 5. robot path planning using atbfo despite classical methods' drawback such as trapped into local minima and high time complexity in high dimensional problems, they have very simple structure which makes them easy to implement. classic artificial potential field (apf) method was originally introduced by khatib [15], as a real time obstacle avoidance method. apf is particularly attractive and has been widely used for path planning related problems for more than two decades because of its elegant mathematical analysis and simplicity [16]. however it suffers from many drawbacks [17]: trap situations due to local minima, no passage between closely spaced obstacles, oscillations in the presence of obstacles and oscillations in narrow passages. in other hand bfo is a simple and effective searching algorithm. consequently a method for hybridizing apf with bfo as lpp technique (making use of both methods' advantages), is introduced in this study. as stated before the environment would be 2d work space with circular obstacles. the mobile robot is represented as a dot by cartesian coordinates (x, y) in the xy-plan. a description for the sensor is needed since the robot is working in totally unknown environment. in this work range based obstacle detection is done using infrared sensor (ir). five ir sensors are positioned in the mobile robot (r) each with 1.2 meter range. these sensors are located in five angles: 0, 45, 90,135 and 180 fig. 2. fig. 2. robot model. in local path planning, finding a path is done on line by only the available readings from the sensors. a function for guiding the robot toward the target is needed. in apf method, two cost functions (attractive and repulsive) are used to attract the robot to the target and push it away from any obstacles at the same time. a combination of both forces drives the robot to its final destination. in this work both attractive and repulsive potential functions (not their gradients forces) are hybridized with bfo to drive the mobile robot. a goal cost function similar to apf [18] is introduced as in eq. (3) and eq. (4). j^)56 = 12 ∗ ξ ∗ ‖pb c − cpe‖f … 3 ‖pb c − cpe‖ = h xb − xe f + yb − ye f … 4 where ξ is a positive constant scaling factor,‖pb c − cpe‖ is the euclidean distance between the robot pb and the target pe . for the obstacle cost function, a repulsive function is assigned for each detected obstacle. as shown in eq. (5). j)lm = n12 ∗ η ∗ o 1d r − 1dos if d r ≤ dmw3mw 0 if d r > dmw3mw c … 5 where , η is a positive constant scaling factor, d r is the distance from robot to the obstacle, do is a positive constant representing the influence distance of the obstacle and dmw3mw is the sensing range. the final function that would guide the robot is the sum of both functions; as shown in eq. (6). je)456 = j^)56 + j)lm … 6 the main target of the bfo algorithm is to find the minimum j , ∈ r² without considering the gradient, ∇j , where θ is the position of a nizar hadi abbas al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 2635(2016) 30 bacterium, and j is cost of goal plus obstacle functions from the environment. j < 0, j = 0, and j > 0 represent that the bacterium at location is in nutrient rich, neutral, and noxious environments respectively. each bacterium tries to climb up the nutrient concentration (i.e., lower and lower values of j ) and avoids being at positions where j ≥ 0. according to bfo algorithm,�~ℎ bacterium at the position takes a chemotaxis step j with the step size c i in the random direction and calculates the cost function j at each step. if the cost function of the new position θ����that is, (θ����), is smaller than the (θ��), then another step size c i in the same previous direction will be taken. this process in the direction of lower cost function will be continued until the maximum number of steps (��) is reached or until bacteria enter a poisonous area. thereafter, in each�� chemotaxis step, the least healthy bacteria (lowest or second half of the population) as stated by the cost function (jθ��) are replaced by the copies of healthy ones (highest or first half of the population). this procedure is called reproduction step, and it is followed by the elimination–dispersal (�#$) event. for each elimination-dispersal event, the bacterium in the population is subjected to elimination dispersal with probability"#$. initially the bacteria are randomly generated and distributed in front of the mobile robot (mr). the angles in which the bacteria are distributed equal to 45° and −45° with respect to the target. the range of distribution must equal or smaller than sensing range (equal or smaller than 1.2 m). these bacteria are searched for the optimal path toward the target position while avoiding the obstacles by helping the robot’s sensors. then the healthiest one which has found the smallest j among other ones is chosen and the mobile robot goes to this position. this process will continue until the target is reached. for choosing the best becterium, cost function j , ∈ r²is tested and compared, which is an attractant-repellent function from the environment. during the algorithm, whenever the mr detects an obstacle within its sensor range, it assigns a value to j)lm (eq. (5)) otherwise its value is zero. in other words, a goal cost function j^)56 (eq. (3)) is assigned to target position throughout the mission. the total cost function which is the sum of both functions je)45 6(eq. (6)) represents the cost function j � defined previously. in order to make a decision for which bacterium would be chosen as the next position that the mr headed to, a difference cost function is defined by: d�� = j� � t + 1 � − j� � t � i = 1,2, … s … 7 after that, the robot position is updated from its current location u t to its next location u t + 1 (pick best direction) and move one-step length equal to lambda (λ) as follows: ɸlwm4 = tan�� θlwm4� t + 1 − θ�� t θlwm4� t + 1 − θ�� t … 8 u t� + 1 = u t� + λ ∗ cos ɸlwm4 … 9 u t� + 1 = u t� + λ ∗ sinɸlwm4 … 10 where ɸlwm4 is the angle between current bacteria coordinate (θ�� t , θ�� t and best next bacteria coordinate (θlwm4� t + 1 , θlwm4� t + 1 and (u t� + 1 , u t� + 1 is mr next step point coordinates that it should headed toward smoothly. 6. simulation results in all simulation arenas, the population size s=100, number of chemotactic steps �� = 8, maximum number of steps that a bacterium can swim �� = 6, number of reproductions nre = 2, number of elimination-dispersals events �#$ = 1, elimination-dispersal probability ped = 0.15 and speed of the movement taken in one step c i =0.1, i = 1,2, . . . s, ξ = 0.1,η = 0.06, do = 1.5, step length lambdaλ = 0.2, f�&'()* = 3,dmw3mw =1.2m. all experiments are achieved the following solutions after executing the algorithm ten times using matlab r2011b programming language. the matlab codes are run on a computer system with 2.13 ghz core i3 cpu, and 2 g ram. 6.1 case study 1: environment with 4 obstacles in case study 1 four obstacles with equal size are situated in the environment. all obstacles' positions are listed in table 1. the cost function representing goal plus obstacles are illustrated in fig. 3 and fig. 4. table 1, obstacles definition for case 1. obstacle radius center(x,y) 1 0.7 (2,2) 2 0.7 (4,4.1) 3 0.7 (7.2,7) 4 0.7 (9,8) nizar hadi abbas al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 2635(2016) 31 fig. 3. cost function used for case 1. fig. 4. contour plot forcost function for case 1. the best path with shortest distance using atbfo algorithm is equal to 14.5346 as illustrated in fig. 5.a second scenario is tested by moving the first obstacle from point (3, 2) to point (2, 2). as stated by [19] the apf fail to reach the target due to local minimum problem. the proposed algorithms were able to overcome this drawback or difficulty as shown in fig.6 with total distance equal to 14.5412. the proposed rpo algorithm in [19] achieved a path with total run time equal to (11.0321s). fig. 5. best shortest path for case 1. fig. 6. best shortest path (2nd scenario) for case 1. 6.2 case study 2: environment with 12 obstacles in case study 2, a complex environment with twelve obstacles in different sizes is presented. all obstacles' positions (center and radius) are listed in table 2. the cost function representing goal plus obstacles are illustrated in fig. 7 and fig. 8. the best path with shortest distance using atbfo algorithm is equal to 14.4797as illustrated in fig. 9, while thebest path with shortest execution time is 8.274537s as in fig. 10. the new bacteria colony approach (nbca) with variable velocity and ga in [11] as gpp algorithms are compared with the proposed lpp algorithms.it achieved path equal to 14.40351 (after divided by scale = 10) and time 62.14s. best result achieved by ga with path of 14.40982 (after divided by scale = 10) and time 34.70 s. in order to investigate the effect of the step size (c i ) on the overall algorithms, the whole test is repeated with smaller step length c i = 0.05. the best two paths according to distance and run time are illustrated in fig. 11 (total distance =14.7852) and fig. 12 (run time =11.628703s). fig. 7. cost function for case 2. -5 0 5 10 15 -2 0 2 4 6 8 10 12 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 goal plus obstacle functions y x jg oa l+ jo bs 0 5 10 -2 0 2 4 6 8 10 12 -1 -0.5 0 0.5 1 goal plus obstacle functions y x jg oa l+ jo bs -2 0 2 4 6 8 10 12 -2 0 2 4 6 8 10 12 x-axis(m) y -a xi s( m ) rpp atbfo -2 0 2 4 6 8 10 12 -2 0 2 4 6 8 10 12 x-axis(m) y -a xi s( m ) rpp atbfo -5 0 5 10 15 -2 0 2 4 6 8 10 12 0 0.5 1 1.5 2 goal plus obstacle functions y x jg oa l+ jo bs jt ot al jt ot al jt ot al nizar hadi abbas al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 2635(2016) 32 table 2, obstacles definitions for case 2. fig. 8. contour plot forcost function for case 2. although large step size speeds up the algorithm and yields to fast convergence, it leads to less smoother paths. fig. 9. best shortest path for case 2. fig. 9. best shortest path for case 2. fig. 11. best shortest path for case 2(2nd test). fig. 12: shortest time path for case 2 (2nd test). 6.3 case study 3: environment with 6 moving obstacles a dynamic environment with six moving obstacles with equal sizes is presented. all obstacles' initial positions (center and radius) are listed in table 3. table 3, obstacles definitions for case 3. obstacle no. radius center(x,y) 1 .4 ( 1.5,1 ) 2 .4 (3,3) 3 .4 (5.5,4.1) 4 .4 ( 6,5) 5 .4 (8,6) 6 .4 (11,10) only the original bfo is hybridized with apf. since the next best location cannot be predicted due to obstacles movement, the calculation for fitness improvement toward best next position is pointless. in all scenarios three obstacles move linearly and the other three circulate in a path with radius equal to 1. the resultant path for the first scenario can be shown in fig. 13 which takes 10.5203 seconds. 0 5 10 -2 0 2 4 6 8 10 12 -1 -0.5 0 0.5 1 goal plus obstacle functions y x jg oa l+ jo bs -2 0 2 4 6 8 10 12 -2 0 2 4 6 8 10 12 x-axis(m) y -a xi s( m ) rpp atbfo -2 0 2 4 6 8 10 12 -2 0 2 4 6 8 10 12 x-axis(m) y -a xi s( m ) rpp atbfo -2 0 2 4 6 8 10 12 -2 0 2 4 6 8 10 12 x-axis(m) y -a xi s( m ) rpp atbfo -2 0 2 4 6 8 10 12 -2 0 2 4 6 8 10 12 x-axis(m) y -a xi s( m ) rpp atbfo obstacle radius center (x,y) 1 1 (1.3,2.5) 2 .8 ( 1,7.6 ) 3 .5 (7.6,.9) 4 1.3 ( 4.5,4.5) 5 .9 ( 1.2,5.5) 6 1.4 ( 8,3) 7 1.2 (6.6,7.7 ) 8 .8 (3.2,1.5 ) 9 .7 (7.5,5.5) 10 .6 ( 8.7,7 ) 11 .8 (3.5,6.6 ) 12 .5 (4.5,9 ) jt ot al nizar hadi abbas al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 2635(2016) 33 fig. 13. 1st scenario pathfor case3. in the second scenario one of the obstacles circulates around the target. the path generated takes 11.5450 seconds and is shown in fig. 14. finally, in this scenario in addition to the six moving obstacles, the target represented by green stars, rotates around center point (9.5, 9.5) with radius equal to 1. the elapsed time was 11.6911 seconds and is shown in fig. 15. fig. 14. 2nd scenario pathfor case3. fig. 15: 3rd scenario pathfor case3. the proposed random particle optimization (rpo) in [19] is compared with the bfo-apf method. the proposed algorithm was able to reach feasible paths and avoid been trapped in local minima situation in three different scenarios. 7. conclusion in this paper, a mobile robot local path planning model based on atbfo is developed. the proposed algorithm models the environment using apf method through two contradictory forces: attractive force for the goal and repulsive force for the obstacles. the atbfo algorithm examines negative feedback from the algorithm to choose appropriate direction vectors (∆�) that guide the search process to promising area with a better local search. in order to investigate the influence of different step size on the rpp problem, two-step sizes were tested. the acquired simulation results show that larger step size speed up the search process but lead to an unfavorable path (less smoothness). conversely, small step size may slow down the algorithm, but it achieves more suitable paths when comes to get smoother ones. three case studies are adopted to evaluate the performance of the proposed algorithm. its performance has been compared with some stateof-the-art algorithms. the atbfo algorithm achieved feasible paths with relatively fast speed range from 2.3m/s for simple environment to 1.85m/s for crowded environment case making it reliable and efficient in practice. list of symbols symbol definition ∆� random direction � positive scaling factor λ robot step length ∅∗ uniformly distributed number between [−1,1] ɸ best picked direction ∗ bacterium position � positive scaling factor � step size $ difference cost function $� positive constant for obstacles d(r) distance from the robot to the obstacle � sensing range �����/�fitness improvement threshold ��/��health goal function �/� health obstacle function ��/2��health total function ��chemotactic no. �#$elimination and dispersal no. �¡#reproduction no. ��swim counter "# elimination parameter "¢ robot position " target position -2 0 2 4 6 8 10 12 -2 0 2 4 6 8 10 12 x-axis(m) y -a xi s( m ) rpp bfo -2 0 2 4 6 8 10 12 -2 0 2 4 6 8 10 12 x-axis(m) y -a xi s( m ) rpp bfo -2 0 2 4 6 8 10 12 -2 0 2 4 6 8 10 12 x-axis(m) y -a xi s( m ) rpp bfo nizar hadi abbas al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 2635(2016) 34 s bacteria colony size £ robot position at time t 8. references [1] n. h. abbas and f. m. ali, “path planning of an autonomous mobile robot using directed artificial bee colony algorithm,”international journal of computer applications,vol. 96, pp.11-16. june 2014. [2] p. a.m. ehlert, “the use of artificial intelligence robots,”report on research project, delft university of technology, netherlands, october 1999. [3] c. a. floudas, ‟deterministic global optimization: theory, methods and applications,”nonconvex optimization and its applications, kluwer academic publishers, dordrecht, the netherlands, 2000. [4] j. c. spall, ‟introduction to stochastic search and optimization: estimation, simulationand control,”wiley-interscience series in discrete mathematics and optimization,wileyinterscience,hoboken,nj, usa, 2003. [5] x. yang, ‟ nature-inspired metaheuristic algorithms,” 2nd edition, by luniver press united kingdom, 2010. [6] h. chen, y. zhu, and k. hu, ‟ adaptive bacterial foraging optimization,”abstract and applied analysis,hindawi publishing corporation, 2011. [7] r. c. eberhart, and j. kennedy, “a new optimizer using particle swarm theory,”inproceedings of the sixth international symposium on micro machine and human science,nagoya, japan, vol. 1, pp. 39-43. 1995. [8] m. dorigo, g. d. caro, and l. m. gambardella, “ant algorithms for discrete optimization,” artificial life,vol.5, no. 2,pp.137-172,1999. [9] d. karaboga, “an idea based on honey bee swarm for numerical optimization, ”technical report, erciyes university, engineering faculty, computer engineering department, pp. 1-10, 2005. [10] k. m. passino, ‟ biomimicry of bacterial foraging for distributed optimization and control,” ieee control systems magazine, june 2002. [11] l. s. coelho and c. a. sierakowski, “ bacteria colony approaches with variable velocity applied to path optimization of mobile robots,” 18th international congress of mechanical engineering, ouropreto, mg, brazil, november 6-11, 2005. [12] h. miao, “ robot path planning in dynamic environments using simulated annealing based approach," master thesis, queensland university of technology, queensland, australia, march 2009. [13] s. das, a. biswas, s. dasgupta1, and a. abraham,‟ bacterial foraging optimization algorithm: theoretical foundations, analysis, and applications”, foundations ofcomputational intelligence, vol. 3, sci 203, pp.23-55,springer, 2009. [14] x. yan, y. zhu, h. zhang, h. chen, and b. niu, “an adaptive bacterial foraging optimization algorithm with lifecycle and social learning,” hindawi publishing corporation ,discrete dynamics in nature and society, pp. 1-20, 2012. [15] ] o. khatib, “real-time obstacle avoidance for manipulators and mobile robots”, int. j. of robotics research, vol. 5, no. 1, pp. 9099, 1986. [16] h. adeli, m.h.n. tabrizi, a. mazloomian, e. hajipourand m. jahed, “path planning for mobile robots using iterative artificial potential field method”,international journal of computer science (ijcsi), vol. 8, issue 4, no 2, july 2011. [17] y. koren and j. borenstein,“potential field methods and their inherent limitations for mobile robot navigation,” proceedings of the 1991 ieeeinternational conference on robotics and automation,sacramento, california, vol. 2, pp.1398-1404,09-11 april1991. [18] l. c.ling, t. jing and y. j.yu, “path planning of mobile robot using new potential field method in dynamic environments”, seventh international conference on natural computation (icnc),shanghai, china, pp.1011-1014, 2628 july 2011. [19] b. mohajer, k. kiani, e. samiei, and m. sharifi, “ a new online random particles optimization algorithm for mobile robot path planning in dynamic environments,” mathematical problems in engineering, hindawi publishing corporation, vol. 2013, article id 491346, 9 pages, 2013. nizar hadi abbas al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 2635(2016) 35 �ت ��� ���ر� ��اا������� ��� أ��س ا��و����� رز��� ا��#" ��! ���� ا� **-�ح �#+ي ��* *()ار ھ�دي �!�س =*>;' +:2اد /78)' ا/-123' / 456 ا/-123' ا/.-,+*()' * **، drnizaralmsaodi@gmail.com : ا/2d,e اb./c,و@?* farah95m@yahoo.com : ا/2d,e اb./c,و@?* * ا� /.� fggghe/ا اiggg2م ھgggld، mgggnو* 'gggd2ا+ 'gggol@ pggg< تrggg+7,و/ sgggt<ر ا*ggg5< د*gggvd*+ 'ggg7twbw/وا ?gggl(lh/ا p<xggg/ا ?gggy 'ggg7l3bw/ت ا*zr+را/,و*ggg5< [(gggo\z '7.ggg]w/ . 2ggg6م raارز>)gggld,o/ '3ggg5h< 'ggg' ا/gggo\z d/eggg5< sgggh/ *gggd,b.e7/ 4-3ggg)] ا/ggg5w*ر. وا/ggg()*3_ '`*ggg5< s.ggg]+ 'hoggg5< 'gggod,a bggg7c 'gggd*-@ 'gggol@ bggg' ا^+;ggg*د ggg< ة*`rbggg5w/ا 'ggg(<ارزr\/ه اiggg2ان ھggg7lz ?gggb/وا 'ggg;(eo/ا p نjgggw/ا pgggc fgggh+ 'ggg(7wc / ل*ggg+ ة*wggg5< *gggd,b.e )ي^rggg8 أي( 'gggol@ pggg< ر*ggg5< د*gggvd^ d<2\bggg1ا 'gggd*-@ 'gggol@ bggg/ا 'gggd2ا+ .'ggg8,hbw/وا 'gggb+*t/ا 'gggm7b\w/ت ا*gggn(e/ا pggg< p(crggg3/ ة*ggg8*h< ogggd,ط pgggc *ggg-z*e_وا *-gggq,c 4gggz 'ggg`,blw/ا 'ggg(<ارزr\/ا . dgggd,=ا ,ggggرة و طrgggow/ا 'ggggld,o/ا p(ggg+ 'ggg@ر*l<'gggtd2` p(d,gggaا p(bld. د*gggvdا ?ggggy 'ggg`,blw/ا 'gggld,o/ه اiggggھ 'ggg(7c*y ,gggg-اظ fggghe/ا اiggggضٍ ھ,gggg< s.ggg]+ رات*gggg5<. 111-116 al-khwarizmi engineering journal,vol. 12, no. 4, p.p. reducing the water hardness ghassan hassan abdulrazzaq department of petroleum processing engineering (received http://dx.doi.org/10.22153/kej.2016.07.002 abstract hard water does not pose a threat to human health these reactions are caused by the high higher fuel consumption for industrial use . for increasing the precipitation of ca 2+ hardness is research has been conducted by changing the number of coil turns and voltage of the system. the spectroscopy electron microscope was used for imaging the produced crystals. that the electromagnetic polarization can be used precipitation percent of caco3. keywords : electromagnetic polarization, 1. introduction water hardness is a measure of the capacity of water to its reaction with soap. hard water more soap foaming. the reason for this is not a single substance, but a diverse dissolved polyvalent metal ions, mainly cautions and magnesium, although much less contributing and other cautions, e.g., barium, iron, manganese, strontium and zinc. hardness is usually expressed in mg /l caco3, the german, french and english of hardness are expressed as follows 1. german hardness = 10 mg cao in 1 liter of water 2. french degree of hardness = 10 mg caco liter of water 3. english hardness = 10 mg caco of water. because the distribution of the earth's crust, magnesium is present in natural waters, where together with calcium makes total hardness of khwarizmi engineering journal,vol. 12, no. 4, p.p. 111116 (2016) water hardness by using electromagnetic polarization method ghassan hassan abdulrazzaq petroleum processing engineering/ college of petroleum & minerals engineering email:ghassanaldoori@yahoo.com (received 20 march 2016; accepted 24 july 2016) http://dx.doi.org/10.22153/kej.2016.07.002 hard water does not pose a threat to human health but may cause precipitation of soap or the high concentrations of ca and mg. in the industry they are undesirable because use .electromagnetic polarization water treatment is a method which can be used 2+ and co3 2ions in hard water to form caco3 which leads to decrease the water research has been conducted by changing the number of coil turns and voltage of the system. the spectroscopy electron microscope was used for imaging the produced crystals. results of that the electromagnetic polarization can be used in precipitation to decrease the hardness of water due to increase in polarization, water hardness,caco3. water hardness is a measure of the capacity of water to its reaction with soap. hard water causes more soap foaming. the reason for this is not a single substance, but a diverse dissolved cautions of calcium, and magnesium, although much less contributing and other cautions, e.g., barium, iron, manganese, ss is usually expressed in mg /l , the german, french and english degrees as follows : german hardness = 10 mg cao in 1 liter of french degree of hardness = 10 mg caco3 in ness = 10 mg caco3 in 0.7 liters because the distribution of the earth's crust, magnesium is present in natural waters, where together with calcium makes total hardness of water. the concentrations of particularly high in the area dom dolomite rocks. this is the case of ground water in the vicinity of tikrit university. natural waters are characterized by a high content of magnesium, whose concentration can be up to 200 mg / dm3, which makes them unfavorable for use in the public water supply, since maximum concentration of magnesium in drinking water according to current regulations is limited to 50 mg / dm3 [1]. in the experiments presented in this paper reduction of the concentration of magnesium in the water that flows into an abandoned mine shaft "undermine" is discussed. this water has shown a stable composition and a negligible presence of microorganisms, and as such has been introduced in the water supply system city . the only drawback is the high content of magnesium, which ranges up to 100 mg / dm however, as the river water composition, that is, it often causes quality of raw water, thereby the consumption al-khwarizmi engineering journal (2016) electromagnetic polarization engineering/ tikrit university cause precipitation of soap or results stone in the boilers. are undesirable because of electromagnetic polarization water treatment is a method which can be used which leads to decrease the water research has been conducted by changing the number of coil turns and voltage of the system. the esults of the investigation indicated dness of water due to increase in the water. the concentrations of mg ions are particularly high in the area dominated by the case of ground water tikrit university. in this area, natural waters are characterized by a high content of magnesium, whose concentration can be up to , which makes them unfavorable for public water supply, since the maximum concentration of magnesium in drinking water according to current regulations is [1]. resented in this paper the he concentration of magnesium in the water that flows into an abandoned mine shaft . this water has shown a stable composition and a negligible presence of microorganisms, and as such has been introduced in the water supply system in the vicinity of tikrit . the only drawback is the high content of magnesium, which ranges up to 100 mg / dm3. however, as the river water has variable sition, that is, it often causes reduction the quality of raw water, thereby the consumption of ghassan hassan abdulrazzaq al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 111116(2016) 112 large amounts of coagulants and flocculants to ensure its physical and chemical safety is increased[3]. the total solute (total dissolved solids) of inorganic salts are dissolved in water with. unit of milligram per liter (mg / l). the majority of salts consisting of cautions of calcium, magnesium, sodium and potassium, and anions are carbonate, bicarbonate, chloride, sulfate and nitrate. the dissolved substance introduced can affect its taste. on the basis of the measured values the palatability of the drinking water is evaluated. table (1) shows some parameters of water [4]. table 1, parameters of water hardness. water mg / l caco3 german degrees° d soft <71.4 <4 easy hard 71.4 to 142.8 4 -8 moderately hard 142.8 to 321.4 8 -18 hard 321.4 to 535.7 18 -30 very hard > 535.7 > 30 1.1. background water is essential raw material for industrial production, energy, food industry for communal needs and more. most requirements for water purity set the food industry (beer, juices) and municipal systems to supply drinking water to citizens. therefore of great importance all processes for treating raw water which must be removed, suspended solid, organic and inorganic chemical compounds, bacteria and chemicals which gives a bad taste and odor. due to the high prices of raw water treatment, appropriate technologies must be combined as best way to establish a balance between the price and the resulting water quality. the processes to treat and recover raw water is the use of electromagnetic field. hydrate ion interaction forces can be influenced by mechanical agitation, temperature, concentration ion and electromagnetic fields. electromagnet field can weaken the ion and water molecules and increase the collision between the ca2+ and co3 2 ions, thus accelerating the rate of nucleation and precipitation of caco3[5] . the chemical features of groundwater depende on the type and amount of dissolved mineral substances. measure the intensity of the melting of rocks in the process, ie corrosion, is hardness water. increased hardness is a sign of intense corrosion and vice versa. determined in forming calcium and magnesium ions in water. total hardness shapes all the calcium and magnesium salts in water[6]. carbonate hardness make hydrogen carbonates and carbonates of calcium and magnesium. the calcium and magnesium hardness values and relationship depend on the composition of the rocks through which water flows. groundwater generally is stiffer than surface water. the concentration of minerals in groundwater increases with length of detention or the flow of water through underground cavities[7]. some studies about the water reported that water hardness can be divided into: • carbonate hardness, comes from ca and mg ions in the form of bicarbonate • non-carbonate hardness, comes from ca and mg ions in the form of sulphates, chlorides and nitrates. • boiling water bicarbonates is converted into carbonates, which are insoluble in what disappears carbonate hardness, left non-carbonate (permanent) hardness. • the waters are classified into four levels of hardness, if hardness is expressed in mg / l caco3 [8]. 2. methodology the principle of this method is to provide an electromagnetic field with certain frequencies in the hard water that flows through a coil with a certain winding number that can promote the process of precipitation of caco3 . this creates small seed crystals in water in the form of very small particles of calcium carbonate prior to entry of the water zone at high temperature. calcium carbonate adheres to the surface of these very small particles and grow in size. these larger particles tend to be removed by the flow . faraday law associated with lenz's law states that the electric field is induced in the magnetic coil when the magnetic field changes with time. the magnetic field is proportional to the current in the coil winding when current changes in coils; the alternating magnetic field is an electric field resisting these changes. this induced ac voltage is high on the side of inspection and tube coil decreases to nothing at the tube coil shows ionic configuration of particles in a magnetic field .pipe center coil and the coil shown in figure (1). ghassan hassan abdulrazzaq al fig. 1. configuration of ionic particles in a magnetic field the carbonate ions co3 -2 will calcium ions ca +2 ,and the result will produce some precipitation and crystallization of calcium carbonate .as illustrated in equation [9] : ca +2 + co3 -2 →caco3 2.1. experimental work treatment process had been conducted by mixing the prepared solution (50 ml) 10 minutes with rate of (19.02 ml /s) temperature equals to the room temperature (25 c) as follows: 1. ewt system used consisted of copper pipe wrapped with copper wire and power supply as shown in figure (1) . sample of hard water is circulated through the electromagnet field using silicon tube (id 6 mm) and peristaltic pump as shown in figure (2). fig. 2. schematic of electromagnet 2. after the ewt treatment, solution in the reservoir tube again was introduced to process to measure the content of ca contained in the solution and to examine the type and number of crystals formed. 3. the average values of caco3 concentrati the two cases ,before and after electromagnetic field water treatment were cpmpared 3. results and discussion afigure (3) shows the effect of voltage changing on the precipitation of caco al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 113 a magnetic field. will react with ,and the result will produce precipitation and crystallization of calcium in equation number (1) …(1) treatment process had been conducted by solution (50 ml) for about /s) ,the solution temperature equals to the room temperature (25 o of copper pipe wrapped with copper wire and power supply as sample of hard water is circulated through the electromagnet field using silicon tube (id 6 mm) and peristaltic pump as equipment. the ewt treatment, solution in the was introduced to the testing process to measure the content of ca +2 ions contained in the solution and to examine the type concentration for the two cases ,before and after electromagnetic were cpmpared . shows the effect of voltage precipitation of caco3. an increasing in the applied voltage will cause increasing in the precipitation percent of caco any increasing in the voltage will cause some increasing in the current through the solenoid coil on ewt tool. this will increase the induction of electromagnetic fields on water according to faraday's law. as a result the increased induction of electromagnetic fields will improve the effectiveness and impact energy between the ions of ca +2 and co3 -2 in solution so that the rate of precipitation of caco3 changing the voltage source are shown in table (2) and the graphical representation is shown in figure (3). table 2, applied voltage vs. percentage of caco precipitation . fig. 3. effect of voltage source changing precipitation of caco3 . bfrom figures (4,5) precipitation of caco3 is increased is duplicated . 0 5 10 15 20 25 30 35 40 1 2 3 4 5 voltage (v) p re ci pi ta tio n (% ) voltage (v) caco3 1 14 2 15 3 17 4 19 5 20 6 22 7 24 8 27 9 28 10 13 11 33 12 35 khwarizmi engineering journal, vol. 12, no. 4, p.p. 111116(2016) increasing in the applied voltage will cause some increasing in the precipitation percent of caco3. ny increasing in the voltage will cause some increasing in the current through the solenoid coil on ewt tool. this will increase the induction of electromagnetic fields on water according to 's law. as a result the increased induction of electromagnetic fields will improve the effectiveness and impact energy between the ions in solution so that the rate of increases. results of ource are shown in table (2) and the graphical representation is shown in vs. percentage of caco3 voltage source changing on from figures (4,5) it can be seen that the is increased when voltage 6 7 8 9 10 11 12 voltage (v) 3 precipitation % ghassan hassan abdulrazzaq al fig. 4. (a) : precipitation of caco3 source of (6 v). fig . 5. precipitation of caco3 when voltage of (12 v). cresults of changing the turns number are shown in table (3) and the graphical representation is shown in figure(6). table 3, number of turns vs. percentage of caco3 precipitation. number of turns caco3 precipitation % 50 24 100 32 150 35 200 39 250 43 al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 114 precipitation of caco3 when voltage precipitation of caco3 when voltage source results of changing the turns number are ) and the graphical ). percentage of caco3 precipitation % fig. 6. effect of changing the number of turns on the precipitation of caco3 d the greater the number of turns are used, the larger electromagnetic fields induced by the water hardness in the coil. this impact on increasing the effectiveness of collisions between ca 2+ and co increasing the precipitation of caco (7,8) shows the increasing precipitation of caco3 number of turns. fig. 7. precipitation of caco3 when turns. fig. 8. precipitation of caco turns 0 5 10 15 20 25 30 35 40 45 50 50 100 150 number of turns p re ci p ita tio n ( % ) khwarizmi engineering journal, vol. 12, no. 4, p.p. 111116(2016) changing the number of turns on 3 . the greater the number of turns are used, the larger electromagnetic fields induced received by the water hardness in the coil. this has an impact on increasing the effectiveness of and co3 2 ions thereby precipitation of caco3 .figures increasing percent of the with increasing the precipitation of caco3 when coil with 100 precipitation of caco3 when coil with 250 150 200 250 number of turns ghassan hassan abdulrazzaq al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 111116(2016) 115 4. conclusion depending on where the rain falls, the water remains naturally soft, or becomes contaminated with various contaminants. water is the best solvent, and as it passes through the soil it, collects various pollution. no method for purifying water can produce laboratory water cleaned of all contaminants. only a combination of effective and economical method can produce satisfactory laboratory water quality. for high efficiency treatment water is used in combination of several methods .results showed that the electromagnet field affected an increase in the precipitation amount of caco3 up to 34% compared to non electromagnetic fields. increasing the voltage, the number of turns of coil causes an increase in precipitation caco3. increasing the electromagnetic field levels caused the caco3 particle to unit with each other to form larger groups .the benefit of this method is in the reduction or elimination of chemical additives method. 5. references [1] patrons, s. a., judd, s. j., stephenson, t., udol, s., and wang, b. l. (1997). magnetically augmented water treatment. inst. chem. eng. 75(b2), 98-104. [2] gehr, r., zhai, z. a., finch, j. a., and fao, s. r. (1995). reduction of soluble mineral concentrations in caso4 water using a magnetic field. water. 29,933-940. [3] arnedo-pena a, c (2007). "domestic water hardness and prevalence of atopic eczema in castellon (spain) school children". salud publica mex. 492 (4): 295–301 [4] cho, y.i.,et al. (1997). theory of electronic anti-fouling technology to control precipitation fouling in heat exchangers. heat mass transfer. 24, 757-770. [5] bott t. r., the fouling of heat exchangers, elsevier science, new york, (1995) [6] muller-steinhagen, h. (1999). cooling water fouling in heat exchangers. in “advances in heat transfer”, vol. 33, pp.415-496. academic press, new york .dreybrodt, [7] eisenlohr, l. (2000.): limestone dissolution rates in karst environments. u:klimchouk, a., ford, d., palmer, a., dreybrodt, w. (ur.): speleogenesis. evolution of karst aquifers, national speleological society, huntsville, 136-148. ford, d., williams p. (1989.): karst geomorphology and hydrology, [8] cho y. i., (2002). efficiency of physical water treatment in controlling calcium scale accumulation in recirculating open cooling water system, ashrae research project 1155-trp. [9] tijing, l. d., et al, an experimental study on the bulk precipitation mechanism of physical water treatment for the mitigation of mineral fouling, international communication in heat and mass transfer, 34, (2007), 673-681. )2016( 111-116، "! � 4، ا���د����12 ا���ارز�� ا������� ا����� ���ن �� �� ا��زاق 116 ا����ه 0,�/$� ا.�-$,�ب ا�*��و�)��ط��� ��ة %$��# ���ن �� �� ا��زاق ,�+�� *()'& /%��� ھ���� ا���$ وا����دن / �� ھ���� ا������ت ا������ hassanaldoori@yahoo.comg: ا�1)'� ا�0(/)و. �"2� ا� ا�/��h7ت ��g.�ت ا����ه وا�/*�/bc -d �b�/. e)'� *(�a %/9'�1@ *)�@ ا�?�<=ن أو و�(�; �:(9 �8)ا 6�7 �45 ا3.��ن '0 � ا���ء ا���) i�> �'م ا�(����و=����k=م وا����ا����ا�(�� l�%ه ا�?���7 ا+� ذات ا�/)اnھ -d��d��ام ا� g/�h� 1=لp+ (�q-7��?. ان �b���+)ةا���ء�ھا������ ا�/ 7 �ام g/�h� ��ch5 (s%9 ا����ه أ�b� إ,)اؤھ� �/' . �b���+ )ةا���ء إن�ز'�دة *)��@ أو 7 �w�d �<�)'�p ا��p/�0ب ا�(w)و+��kط��ھا��)'�p ا�/'/ co3وا'=.�ت ا�()<=.�ت ا����ca 2+ �1 اl/8ال ا'=.�ت ا�(����=م ا��=,�1 +�� '�/e �7; ز'�دة *���p ا���ء �caco3/(='�1�1c iت ا���)ة��ه dا�� -2 �ام ��)ا�g/�h� ��zh+ (s%و,��; أ . i�/p'(�> [41إ,)اء ا� �� ا����$ : *wbا� (��k/> -ھ ��.�sا� �p'(د ���ت ا���\ وا���7 (��k/> 6ام .ا[و��g/ا� �* 91 �w/ودرا� �b*د ���ت ا��ا���()و�(=ب �/?=') ا��1�14ت ا����7 (��k* �� ا�z�>(w)ا����$ و 91 و<�wbز'�دة ا� � ا��/�ez ا�c \� .��5�4=ل ا[.1=ب و<� . �1�1c caco3ت أل ���7�d ا��p/�0ب ا�(w)و+��kط��dز'�دة .��1 *)��@ و<�=رة أ_1/& <4d6963726f736f667420576f7264202d20edc7d3e3ede420e6dac7d5e320e6cf20dae1c7c1312d2039> al-khwarizmi engineering journal al-khwarizmi engineering journal,vol. 13, no. 3, p.p. 19 (2017) delignification of date palm fronds using modified organosolv technique yasmeen salih mahdi* asem hassan mohammed** alaa kareem mohammed*** *, ***department of biochemical engineering / al-khwarizmi engineering college / university of baghdad **institute of technology baghdad/ chemical industries/ middle technical university *email: yasmeensalih90@gmail.com **email: asemh2005@yahoo.com ***email: alaauniv@yahoo.com (received 2 july 2017; accepted 18 july 2017) https://doi.org/10.22153/kej.2017.07.001 abstract in this study, modified organic solvent (organosolv) method was applied to remove high lignin content in the date palm fronds (type al-zahdi) which was taken from the iraqi gardens. in modified organosolv, lignocellulosic material is fractionated into its constituents (lignin, cellulose and hemicellulose). in this process, solvent (organic)-water is brought into contact with the lignocellulosic biomass at high temperature, using stainless steel reactor (digester). therefor; most of hemicellulose will remove from the biomass, while the solid residue (mainly cellulose) can be used in various industrial fields. three variables were studied in this process: temperature, ratio of ethanol to water and digestion time. statistical experimental design type central composite design (ccd) has been used to find a mathematical relationship between the variables and the remaining lignin percent as dependent variable. the results obtained in this study were represented by a polynomial mathematical equation of the second degree. the results showed that the best digestion time was (80 minutes), which gave the best percent remaining concentration of lignin (3%) at temperature of 185oc and ratio of ethanol: water equal to 50: 50 wt/wt. in order to reduce digesting time, the effect of using different catalysts have been studied such as (naoh, h2so4, ca (oh) 2) at low concentration (0.025, 0.025, 0.05m) respectively. it was found that the best catalyst is sodium hydroxide at concentration (0.025) mol/l which gave the same percent of lignin 3% but with low digestion time about 30 min. keywords: biomass pre-treatment, delignification, lignin, organosolv, date palm fronds. 1. introduction delignification is removal of lignin from woody tissue as by natural enzymatic or industrial chemical processes so that it can be used for applications like making rayon or making paper [1]. lignin is an organic substance binding the cells, fibers and vessels which constitute wood and the lignified elements of plants, as in straw. it is the most abundant renewable carbon source on earth [2]. there are several methods concerning delignification. kraft process is one of these methods [3], which is capable to remove about 95% of lignin from woody biomass. in this method, the wood chips are digesting at high pressure and elevated temperature in the existence of whit liquor (solution of sodium hydroxide and sodium sulfide). this process is carried out either batch or continuous in a bioreactor that called digester [4]. another method is oxygen delignification, which is a process between cooking and bleaching sequences, where part of the residual lignin left in pulp after cooking is removed using oxygen and alkali[5]. the targeted reactions are the oxidation of lignin and breaking it down parts which dissolve in alkali, as well as destroying the colored groups in lignin and removal of impurities, such as resin. oxygen yasmeen salih mah al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 19 (2017) 2 delignification is not so efficient as kraft method, it removes only 55% of lignin [6]. it is, however, often used as a supplementary tandem process to the more traditional kraft method. delignification using microorganisms was also investigated. in production of bioethanol from plant material, removal of lignin using microbial reaction was used simultaneously with conversion of cellulose to bioethanol at low level of temperature [7]. scientist also try to change the content and structure of lignin by microorganisms in order to either improve its digestibility to animals [7] or to increase the utility of the cell walls for biofuel production paper manufacturing [8]. another technique of delignification is organosolv process which involves contacting a lignocellulosic feedstock such as chipped wood with an aqueous organic solvent at temperatures ranging from 150 to 220 °c [9]. solvents used include acetone, methanol, butanol, ethylene glycol, formic acid, and acetic acid. the concentration of solvent in water ranges from 20 to 80% [10] . organosolv has several advantages when compared to other popular methods such as kraft or sulfite pulping since it has the ability to obtain relatively high quality lignin [4]. organosolv solvents are easily recovered by distillation, leading to less water pollution and elimination of the odor usually associated with kraft pulping[11]. the purpose of the current study is delignification of date palm fronds in order to remove about 95% of its lignin content using modified organosolv technique. 2. experimental work 2.1. materials and methods 2.1.1. composition analysis of data palm fronds the date palm fronds samples were collected from babylon garden from one kind of date palm (al-zahdi) and stored in presterilized bags in refrigerator freeze. the samples then transferred to the laboratory for testing and before being treated, impurities were removed by washing them with distilled water for several times .after that the samples were shredded using electric cutter and crushed with humor then sieved. fragments with particle size of (90-270) μm were selected for the steps of analysis. the composition of date palm fronds (leaves and stalk) were determined according to national renewable energy laboratory (nrel) laps for compositional analysis [12]. table (1) shows the composition of fronds (leaves and stalk). table 1, the composition of date palm fronds (leaves and stalk) based on dry weight wt % 2.1.2. preparation of ethanol solution solutions of ethanol were prepared with different ratios of ethanol: water. they are: (20:80, 33:67, 50:50, 67: 33 and 80:20 wt/wt). 200 ml of each solution was prepared. for example to prepare 200 ml solution with ratio ethanol: water of 20:80, 41.666 g of ethanol (96% concentration) is completed to 200 ml with distilled water. in the same way, the other solutions were prepared by completing appropriate amount of ethanol to 200 ml with distilled water. 2.1.3. description of the reactor two liter stainless steel reactor was used in this study with 11 cm in diameter and 21cm length. the reactor was heated from the side through a jacket-type heater, while heated from bottom by magnetic stirrer hot plate as shown in figure (1). the reactor was provided with a thermocouple equipped with temperature controller to control the temperature inside the reactor. the pressure inside the reactor was indicated using pressure gauge. sample carbohydrate lignin ash extractive protein leaves 52 27 8 10 4 stalks 59 23 7 8 3 yasmeen salih mah al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 19 (2017) 3 fig. 1. a: schematic diagram of the reactor. b: the reactor and its components which used in experiments. 2.1.4. procedure lab scale experiments were performed in two liter autoclave batch reactor. the date palm fronds (biomass) were milled to about 0.18mm. a suspension of biomass-water-organic solvent (ethanol) was made (typically, 200 ml solvent per 20 g biomass). the effect of ethanol solvent is to hydrolysed lignin in the sample but has no effect on cellulose[13]. in some experiments, catalyst was added. this suspension was heated to a specific reaction temperature (in the range 150 200oc) while being stirred. this suspension then kept at its set point during a certain reaction time (typically, 60 min) and subsequently cooled down. after filtration of the resulting slurry, the solid residue was washed with an identical organic solvent-water mixture and dried at 105oc. from the filtrate solution, samples were taken for uv analysis. 2.1.5. washing and filtration of the sample after delignification after the run completed, the treated sample was washed with ethanol /water solution( 80:20 , ethanol: water) and then with distilled water for several times until the color of liquor change from brown color to colorless , then the solution was filtered using vacuum pump as shown in the figure ( 2 ). ti tc t t 1 2 3 4 5 6 8 7 1digester 2jacket heater 3-pressure gauge 4-temperature indicator 5-temperature transmitter 6-temperature controller 7-interface 8magnetic stirrer hot plate a b yasmeen salih mah al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 19 (2017) 4 fig. 2. vacuum pump for washing and filtration process. 2.1.6. bleaching bleaching is a chemical processing carried out on various types of wood pulp to remove the color of the pulp, so that it becomes whiter. the goal of bleaching chemical pulps is to remove essentially all of the residual lignin; hence the process is often referred to as delignification[4]. chlorine is the basis for the most common bleaching process. three grams of dried sample was weighted and put into 500 ml flask, then 250ml of sodium chlorite solution (60 g/l sodium chlorite and 60 g/l sodium acetate) was added, the sample was soaked for four days[14]. then it was washed with distilled water for several times, followed by extraction with 0.15 n naoh twice and then washed with hypochlorite and distilled water thoroughly. finally, the sample was freeze-dried. it was note that the color was changed from dark brown to white as show in the figure (3). fig. 3. the sample after bleaching. 2.1.7. lignin content the lignin content was determined according to the renewable energy laboratory standard procedure[15], 0.3 g of date palm frond with particle size less than 180 μm was put into a dried test tube and then 3 ml of h2so4 72% was added to it. the tube was placed in water bath at 30oc for 1hr then the sample mixed with 84 ml distilled water in glass bottle and placed in autoclave for 1 hr at 125oc. then the sample filtered with weighed crucible using vacuum pump. two types of lignin were obtained, lignin acid soluble and lignin acid insoluble. the weight percent of lignin acid insoluble residue (air) can be calculated by eq. (1). %air = weight �� ���� ���� ��� − weight �� ���� odw������ ∗ 100 …(1) odw: oven dry weight which can be calculated using equation (2). odw = weight������ ��!"� #���# − weight������ �!$�� #���# weight������ ��!"� #���# …(2) two milliliter of liquor was diluted with 4 ml distilled water in dried test tube ,then the(uvabs) absorbance was measured at wave length 320 nm [16]. the amount of acid soluble lignin (asl) can be calculated using equation (3) %asl = uv abs ∗ volume!��$��$� ∗ dilution ε ∗ odw������ ∗ pathlength ∗ 100 … (3) where: volume of filtrate was taken = 86.73 ml ε = absorptivity of biomass at specific wavelength equal to (11.4)[6] path length = path length of uv-vis cell in cm (1cm) dilution can be calculated using equation (4) dilution = volume ������ + volume#���$�9: �"�;�9$ volume ������ … (4) the total amount of lignin can be calculated using equation (5). %lignin = % air + %as . . . (5) 3. results and discussion three parameters have been studied (temperature, ethanol/water ratio and time) with respectively ranges (150-220) co, (20-80) wt.%, (20-80) min. seventeen experiments were conducted in this study with parameters values were selected according to the statistical yasmeen salih mah al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 19 (2017) 5 experimental design type (ccd). the experimental values were shown in table (2). table 2, effect of experimental parameters on lignin percent. runs temperature, oc ratio ethanol :water time, min lignin % content 1 185.00 50.00 80.00 3 2 150.00 50.00 50.00 9 3 205.21 67.32 67.32 5.5 4 164.79 67.32 32.68 12.5 5 185.00 50.00 50.00 6 6 185.00 80.00 50.00 8 7 220.00 50.00 50.00 5.5 8 185.00 20.00 50.00 10 9 164.79 32.68 32.68 11.5 10 164.79 67.32 67.32 6.8 11 185.00 50.00 20.00 8 12 164.79 32.68 67.32 6 13 185.00 50.00 50.00 6.2 14 205.21 32.68 32.68 8 15 205.21 32.68 67.32 7.5 16 185.00 50.00 50.00 6.3 17 205.21 67.32 32.68 6.5 3.1. mathematical model in the experimental work, the values of independent variables, which were temperature, ethanol: water ratio and digesting time, were selected according to central composite design (ccd). design of experiments (doe) program using central response technique has been used to find a mathematical relationship between the three dependent variables and the independent variable which is the remaining lignin percent in the sample. a second – order polynomial correlation was obtained as shown in eq.(6). y = ba + bbxb + bdxd + bexe + bfxbxd + bgxbxe + bhxdxe + bijk l + bmxd d + bnxe d … (6) where b0, b1, b2…b9 are coefficients of polynomial equation. x1, x2 and x3 are the real variables(x1: temperature, x2: ethanol/water ratio, x3: time) y is the remaining lignin percent 3.2. estimation the coefficients of the second order equation the coefficients of equation (6) can be determined by using computer software (design expert) so equation (6) can be written as follow: y = 6.17 1.10 x1-0.37 x2 1.53x3 0.66 x1 x2 +1.21 x1 x3 -0.088 x2 x3 +0.51 xb d+1.09 xd d0.072 xe d …(7) correlation coefficient = 0.9681 relative standard deviation = 3.6% 3.3. effect of temperature and ethanol/water ratio on lignin content according to the mathematical model of eq. (6) the effects of temperature and ethanol/water ratio were studied at certain value of time. figure (4) shows the contours of lignin percent content at different values of temperature and ethanol/water at constant time 20 min. minimum value of lignin percent contained was 6.89% which obtained at a lowest temperature of 191oc and solvent ratio (ethanol: water equal to 50:50 wt/wt). decreasing the temperature below 191oc will led to increase the value of lignin% content in the sample. this is because decreasing the temperature will prevent full fractional of lignocellulosic material and then the lignin percent will be increase at temperature below 180oc. yasmeen salih mah al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 19 (2017) 6 fig. 4. effect of temperature and ethanol/ water ratio on lignin percent at constant time 20 min. figure (5) shows the effect of temperature and ethanol/water ratio on lignin percent content at constant time 50 min. the best lignin percent lie on contour 6.11% which was obtained at lowest temperature 185oc and ethanol: water ratio at 50:50. on comparison with figure (4) at constant time 20 min, it can be concluded that increasing digestion time leads to decrease the temperature as well as improve the removal of lignin. although increasing temperature will lead to decrease the lignin content, but it is not recommended to exceed the digestion temperature above 185oc because many changes will happen to the cellulose structure and destroy it[17]. fig. 5. effect of temperature and ratio on lignin percent at constant time 50 min. figure (6) shows that best lignin percent content (3.08%) was obtained when use digestion time 80 min at temperature is 185oc and solvent ratio of 50:50. so this is the optimum operating condition for lignin removal. fig. 6. (effect of temperature and ratio on lignin percent at constant time 80 min). 3.3. effect of using catalyst as it has been shown from the above context, the time of digestion is very important parameter in the delignification process and time 80 min gave perfect lignin percent content, but this time is too long therefore; a possibility to improve the organosolv process might be the application of a catalyst. in the literature, h2so4, naoh and ca (oh) 2 are a well-known catalysts for biomass pretreatment processes [9]. catalysts were used with concentration of 0.025m for each of h2so4 and naoh and 0.05m for ca (oh) 2. the experiments were conducted at 180oc and ratio of ethanol: water equal to 50:50. figure (7) shows that the treated sample without catalysts gave 3% lignin content and 80 min digestion time, while all catalysts reduced the digestion time to 30 min, but lignin percent content was minimum (3%) when using naoh. other catalysts gave higher lignin content as shown in figure (7). so it can be concluded that among the catalysts used in the experiments sodium hydroxide was the most efficient in reducing time of digestion while keeping the lignin content at minimum value. on the other hand sodium hydroxide has another benefit. it is working on reducing the degree of polymerization of remains sample (mainly cellulose) and this is important in the subsequent steps in the process of synthesis of rayon [18]. yasmeen salih mah al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 19 (2017) 7 fig. 7. effect of different catalysts on lignin percentage content. conditions are 185oc, and ratio ethanol: water = 50:50. 4. conclusion based upon the results obtained so far, there is a possibility to dignify the date palm fronds using modified organosolv. the more effective parameters in the delignification process were: temperature, ethanol/ water ratio and time. without catalyst, the optimum conditions for delignification process were: temperature 185oc, ethanol: water 50:50 and digestion time 80 min. in order to reduce the digestion time, three types of catalysts were tested: h2so4, naoh and ca (oh) 2. among them, sodium hydroxide (0.025m) was found the best one which reduces the time from 80 min to 30 min. 5. references [1] v. chain, e. ec, d. g. energy, e. let, e. have, e. consultation, b. era, n. e. t. cofund, i. agenda, e. e. commission, e. strategy, e. oecd, and f. a. o. a. outlook, “pretreatment of biomass for conversion to advanced biofuels pretreatment of biomass to facilitate conversion to bioenergy or biofuels overview latest news energy densification organosolv process,” pp. 1–2, 2013. 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[8] l. mesa, e. gonzález, c. cara, m. gonzález, e. castro, and s. i. mussatto, “the effect of organosolv pretreatment variables on enzymatic hydrolysis of sugarcane bagasse,” chem. eng. j., vol. 168, no. 3, pp. 1157– 1162, 2011. [9] w. j. j. huijgen, r. r. den laan, and j. h. reith, “modified organosolv as a fractionation process of lignocellulosic biomass for co-production of fuels and chemicals,” 16th eur. biomass conf. exibition, spain, no. june, pp. 2–6, 2008. [10] p. j. kleppe, “kraft pulping,” tappi, vol. 53, no. 1, pp. 35–47, 1970. [11] d. chiaramonti, m. prussi, s. ferrero, l. oriani, p. ottonello, p. torre, and f. cherchi, “review of pretreatment processes for lignocellulosic ethanol production, and development of an innovative method,” biomass and bioenergy, vol. 46, pp. 25–35, 2012. 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[15] a. sluiter, b. hames, r. ruiz, c. scarlata, j. sluiter, d. templeton, and d. c. nrel, yasmeen salih mah al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 19 (2017) 8 “determination of structural carbohydrates and lignin in biomass determination of structural carbohydrates and lignin in biomass,” vol. 2011, no. april 2008, 2012. [16] r. sierra, m. t. holtzapple, and c. b. granda, “long-term lime pretreatment of poplar wood,” aiche j., vol. 57, no. 5, pp. 1320–1328, 2011. [17] s. e. zayed, a. b. a. adam, e. a. hassan, and m. a. el-kady, “renewable egyptian lignocellulosic materials as alternative raw material for particleboard manufacturing,” vol. 18, no. 2, pp. 262–272, 2015. [18] n. mosier, c. wyman, b. dale, r. elander, y. y. lee, m. holtzapple, and m. ladisch, “features of promising technologies for pretreatment of lignocellulosic biomass,” bioresour. technol., vol. 96, no. 6, pp. 673– 686, 2005. )2017( 1-9، صفحة 3د، العد13دجلة الخوارزمي الهندسية المجلم ياسمين صالح مهدي 9 بأستخدام طريقة المذيب العضوي المعدلهازالة اللكنين من سعف نخيل التمر **عالء كريم محمد* عاصم حسن محمد** ياسمين صالح مهدي* جامعة بغداد كلية الهندسة الخوارزمي/ االحيائية/قسم الهندسة الكيميائية ،*** قسم الصناعات الكيمياوية/ الجامعة التقنية الوسطى / معهد التكنولوجيا بغداد ** yasmeensalih90@gmail.com*البريد االلكتروني: asemh2005@yahoo.com:البريد االلكتروني** alaauniv@yahoo.com:البريد االلكتروني*** الخالصة التمر الزالة كمية اللكنين العالية الموجودة في سعف نخيل ) modified organosolv( تطبيق طريقة المذيب العضوي المعدلة الدراسة هذه في تم بأستخدام الهيمي سليلوز واللكنين )و بتجزئة الكتلة الحيوية الى مكوناتها الثالثة الرئيسة ( السيليلوز وذلك الزهدي)نوع المأخوذ من البساتين العراقية ( عند درجات حرارية عالية آلزالة اللكنين وتحلل الهيميسلسلوز بينما البقايا الصلبة ةوخليط من األيثانول والماء بنسب محدد) digester( هاضم نسبة و درجة الحرارة . تم دراسة ثالثة متغيرات في هذه العملية وهي :ي العمليات الالحقة آلستخدامه في مجاالت صناعية مختلفة(السيليلوز) يتم أذابته ف .الوقت و األيثانول الى الماء اليجاد عالقة رياضية تربط المتغيرات الثالثة مع نسبة اللكنين المتبقية بالنموذج. النتائج central composite designتم أستعمال طريقة من خالل من الدرجة الثانية. ) polynomialمتعددة الحدود ( معادلة رياضية بتم تمثيلها والتي العملية التي تم الحصول عليها بأستخدام هذه الطريقة عند افضل درجة حرارة %٣المتبقي بنسبة أعطى أفضل أزالة للكنين والذي دقيقة ) ٨٠( للهضم هو وجد أن افضل وقتالنتائج التي تم الحصول عليها تم دراسة تأثير استخدام عوامل مساعدة تقليل الزمن الالزم لعملية الهضموبهدف نسبة وزنية. ٥٠: ٥٠الماء تساوي ل : درجة مئوية ونسبة أيثانو ١٨٥ أن افضل عامل مساعد هو وقد وجد على التوالي ، .) مول لكل لتر٥٬٠٫٠٢٥٫٠٬٠٥٠٫٠٢) بتراكيزقليلة (4so2h ,2ca(oh) , naohمختلفة مثل ( .دقيقة ٣٠بزمن أقل حوالي ولكن %٣ نفسها المتبقي حيث أعطى نسبة اللكنين) مول لكل لتر ٠٫٠٢٥بتركيز( هيدروكسيد الصوديوم 20-36 al-khwarizmi engineering journal,vol. 11, no. studying and modeling the effect of graphite powder mixing electrical discharge machining on the main process characteristics ahmed n. al-khazraji *, ** department *** department (received abstract this paper concerned with study the effect of a graphite micro powder mixed in the kerosene dielectric fluid during powder mixing electric discharge machining (pmedm) of high carbon high chromium aisi d2 steel. the type of electrode (copper and graphite), the pulse are taken as the process main input parameters. the material removal rate mrr, the tool wear ratio twr and the work piece surface roughness (sr) are taken as output parameters to planned using response surface methodology (rsm) design procedure. empirical models are developed for mrr, twr and sr, using the analysis of variance (anova).the best results for the productivity of the when using the graphite electrodes, the pulse current (22 a), the pulse on duration (120 µs) and using the graphite powder mixing in kerosene dielectric reaches (82.84mm³/min). the result gives an improvement in material removal rate of (274%) with respect to the corresponding value obtained when copper electrodes with kerosene dielectric alone. the best results for the tool wear ratio (twr) of the process obtained when using the copper electrodes, the pulse current (8 a), the pulse on duration (120 µs) and using the kerosene dielectric alone reaches (0.31 %). the use of graphite electrodes, the kerosene dielectric with 5g/l graphite powder mixing, the pulse current (8 a), the pulse on duration (40 µs) give the best surface roughness (141%) with respect to the corresponding value obtained when using copper electrodes and the kerosene dielectric alone with the same other parameters and machining conditions. keywords: edm, rsm, mrr, twr, sr, aisi d2die steel, graphite powder mixing 1. intro duction edm process is useful for the machining of high-value components, such as mould tools and dies as well as aerospace engine components. the process is particularly advantageous when compared to conventional mechanical cutting operations, since strength and toug work piece are not factors in its machinability, and instead the thermal and electrical properties determine the ability for a material to be cut [1,2]. edm is known to significantly affect the surface of cut materials compared to many other manufacturing processes, such khwarizmi engineering journal,vol. 11, no. 3, p.p. 20-36 (2015) studying and modeling the effect of graphite powder mixing electrical discharge machining on the main process characteristics khazraji * samir a. amin ** saad m. ali *** department of mechanical engineering / university of technology department of mechanical engineering / university of karbala *email: dr_ahmed53 @yahoo.com **email: alrabiee2002@yahoo.com ***email: smaengg@yahoo.com (received 1 february 2015 ; accepted 11 may 2015) concerned with study the effect of a graphite micro powder mixed in the kerosene dielectric fluid during powder mixing electric discharge machining (pmedm) of high carbon high chromium aisi d2 steel. the type of ulse current and the pulse-on time and mixing powder in kerosene dielectric fluid are taken as the process main input parameters. the material removal rate mrr, the tool wear ratio twr and the work piece surface roughness (sr) are taken as output parameters to measure the process performance. the experiments are planned using response surface methodology (rsm) design procedure. empirical models are developed for mrr, twr and sr, using the analysis of variance (anova).the best results for the productivity of the when using the graphite electrodes, the pulse current (22 a), the pulse on duration (120 µs) and using the graphite powder mixing in kerosene dielectric reaches (82.84mm³/min). the result gives an improvement in material removal e of (274%) with respect to the corresponding value obtained when copper electrodes with kerosene dielectric alone. the best results for the tool wear ratio (twr) of the process obtained when using the copper electrodes, the pulse on duration (120 µs) and using the kerosene dielectric alone reaches (0.31 %). the use of graphite electrodes, the kerosene dielectric with 5g/l graphite powder mixing, the pulse current (8 a), the pulse on duration (40 µs) give the best surface roughness of a value (2.77 µm).this result yields an improvement in sr by (141%) with respect to the corresponding value obtained when using copper electrodes and the kerosene dielectric alone with the same other parameters and machining conditions. rsm, mrr, twr, sr, aisi d2die steel, graphite powder mixing. process is useful for the machining of value components, such as mould tools and dies as well as aerospace engine components. the process is particularly advantageous when compared to conventional mechanical cutting operations, since strength and toughness of the work piece are not factors in its machinability, and instead the thermal and electrical properties determine the ability for a material to be cut [1,2]. edm is known to significantly affect the surface of cut materials compared to many other as milling, grinding or electrochemical reduced potential fatigue life of edm components [3]. aisi d2 cold work also known as die steels, is one of the most popular high-chromium and high and it is characterized by its high compressive strength and wear resistance, good through hardening properties, high stability in hardening and good resistance to tempering a high alloy steels fe-cr the ability to preserve its desirable mechanical properties intact upon cycling over a range of temperatures, which can be an advantage for applications including, piercing and blanking dies, al-khwarizmi engineering journal (2015) studying and modeling the effect of graphite powder mixing electrical discharge machining on the main process characteristics saad m. ali *** of technology mechanical engineering / university of karbala concerned with study the effect of a graphite micro powder mixed in the kerosene dielectric fluid during powder mixing electric discharge machining (pmedm) of high carbon high chromium aisi d2 steel. the type of on time and mixing powder in kerosene dielectric fluid are taken as the process main input parameters. the material removal rate mrr, the tool wear ratio twr and the work measure the process performance. the experiments are planned using response surface methodology (rsm) design procedure. empirical models are developed for mrr, twr and sr, using the analysis of variance (anova).the best results for the productivity of the process (mrr) obtained when using the graphite electrodes, the pulse current (22 a), the pulse on duration (120 µs) and using the graphite powder mixing in kerosene dielectric reaches (82.84mm³/min). the result gives an improvement in material removal e of (274%) with respect to the corresponding value obtained when copper electrodes with kerosene dielectric alone. the best results for the tool wear ratio (twr) of the process obtained when using the copper electrodes, the pulse on duration (120 µs) and using the kerosene dielectric alone reaches (0.31 %). the use of graphite electrodes, the kerosene dielectric with 5g/l graphite powder mixing, the pulse current (8 a), the pulse on of a value (2.77 µm).this result yields an improvement in sr by (141%) with respect to the corresponding value obtained when using copper electrodes and the kerosene dielectric alone grinding or electrochemical machining, and the reduced potential fatigue life of edm components tool steels of series d, nown as die steels, is one of the most m and high-carbon steels and it is characterized by its high compressive strength and wear resistance, good throughhardening properties, high stability in hardening and good resistance to tempering-back. aisi d2is cr-c-base. this alloy has the ability to preserve its desirable mechanical properties intact upon cycling over a range of temperatures, which can be an advantage for applications including, piercing and blanking dies, ahmed n. al-khazraji al-khwarizmi engineering journal, vol. 11, no. 3, p.p. 2036 (2015) 21 punches, shear blades, spinning tools, slitting cutters, as well as variety of higher-end wood working tools [4] edm process is very demanding but the mechanism of process is complex and far from completely understood. therefore, it is hard to establish a model that can accurately predict the response (productivity, surface quality etc.) by correlating the process parameter, though several attempts have been made [5]. since it is a very costly process, optimal setting of the process parameters are up most important to reduce the machining time to enhance the productivity [6]. improving the mrr and surface quality are still challenging problems that restrict the expanded application of the technology [7]. among several attempts, rsm was employed by n. s. khundrakpam et al [8], have been used a central composite design (ccd) for combination of variables and response surface method (rsm) to explore the influence of process parameters, such as peak current, powder concentration and tool diameter on the material removal rate (mrr) on en-8 steel. analysis of variance (anova) was performed to obtain the significant coefficients. pradhan and biswas [9], investigated the influence of processing variables on the responses mrr and sr. ranganathan and senthivelan [10], used powder mixing for optimization of sr, twr and mrr. pradhan and biswas [11], have established empirical models variables with mrr and sr. j. lin and c. lin [12], optimized the machining parameters with responses mrr, sr, and electrode wear ratio using of orthogonal array. singh et al. [13], optimized mrr, twr, sr on edm. reddy and rao [14], obtained the optimal levels of process in drilling of aluminum 6061 alloy using design of experiments based grey relational analysis. saurav and sankar [15], studied the effect of parametric influence of wire edm on mrr, sr and width of cut to establish mathematical models and simulation. b. reddy et al. [16], studied the effect of fine metal powders, such as aluminum and copper are mixed to the dielectric fluid, during electric discharge machining (edm) of aisi d3 steel and en-31 steel. material removal rate and surface roughness are taken as output parameters to measure the process performance. the obtained outcomes of experiments indicated that the addition of metal powders in dielectric fluid increases the material removal rate and improves the surface quality. this paper attempted to study the effect of graphite powder mixed to the dielectric fluid with other input parameters like, peak current and pulse on time, during electric discharge machining (edm) of aisi d2die steel. material removal rate, electrodes wear rates and surfaces roughnesses are taken as output parameters to measure the edm and pmedm process performance. this paper is also attempted to develop models for sr, mrr and twr by using the response surface methodology (rsm) technique. two sets of experiments are designed for performing the experiments in pure kerosene dielectric for the first set, while the second is the addition of abrasives graphite powders mixed with dielectric fluid in order to improve the process productivity, efficiency and the workpiece surface quality. 2. experimental work the selected aisi d2 die steel workpiece material, was tested firstly for chemical composition examination. three samples were tested by using the ametexspectro max material analyzer. the results with the equivalent values according to astm a 681-76 standard specification for alloy and die steels [17] are listed in table (1). four specimens were prepared for tensile tests on the bases on astm-77 steel standards for flatwork piece [18]. the same specimens were tested for rockwell hardness tests. the tests results are given in table (2). two types of electrodes materials, copper and graphite were selected. the electrodes were manufactured with a square cross-section of 24 mm and 30 mm lengths, with a quantity of 24 pieces for each type, as shown in figure (1). the main designed edm parameters are the gap voltage vp (140 v), the pulse current ip (8 and 22 a), the pulse on time duration period time ton (40 and 120 µs), the pulse off time duration period toff (14 and 40 µs), the graphite powder concentration (0 and 5g/l), the kerosene dielectric adjusted from both sides of the w/p with a flashing pressure = 0.73 bar (10.3 psi) and the electrode polarity (+). the edm experiments were done on acracnc-eb edm machine with all the manufactured attachments shown in figure (2). a stainless steel container (of about 30 liters volume and dimensions 400 mm hight, 300mm length, 230 mm width and plate thickness 3 mm) was manufactured. it contains of a special kerosene dielectric pump, an electric motor (300 rpm) connected to a mixture contains a stainless steel impellers, a workpiece clamping fixture, valves and pipe accessories. for the power supply, an ahmed n. al-khazraji al-khwarizmi engineering journal, vol. 11, no. 3, p.p. 2036 (2015) 22 ac/dc converter for driving the special kerosene pump was attached in an electrical board. this board contains also a pressure gauge (one bar capacity), wiring, switches and piping accessories. the manufacturing of the stainless steel container were completed by using the tig argon inert gas welding process, as shown in figure (2). the graphite powders substances were tested for chemical compositions by using the x-ray diffraction apparatus, and then the powder was tested to measure its grains sizes using the laser diffraction particle size analyzer. the average grain size is (44,866 µm) for graphite powder as given in the test certificates. the surface roughness for each work piece and electrode (copper and graphite) were measured before and after edm and pmedm machining by using the portable surface roughness tester. all the w/p specimens and electrodes are weighed before and after edm machining too by using the electronic weighting balance with accuracy of (0.0001g). fig. 1. the copper and graphite electrodes and workpieces pmedm processes. fig. 2. the (cnc) edm machine with all the manufactured accessories designed for the implementation the pmedm experiments. table 1, the chemical compositions for the selected workpiece material and the equivalent given by the standard for aisi d2die steel. sample c% si % mn % p % s % cr % mo% ni % co % cu% v % fe% tested samples 1.51 0.174 0.264 0.014 0.003 12.71 0.555 0.158 0.0137 0.099 0.306 bal. standard aisi d2 [17] 1.40 to 1.60 0.60 max. 0.60 max. 0.03 max. 0.03 max. 11.00 to 13.00 0.70 to 1.20 1.00 max. 1.10 max. bal. ahmed n. al-khazraji al-khwarizmi engineering journal, vol. 11, no. 3, p.p. 2036 (2015) 23 table 2, the mechanical properties for the selected materials. ultimate tensile stress (n/mm²) yield strength (n/mm²) elongation (%) hardness (hrb) average 704.25 415.25 18.125 90.25 3. results and discussions 3.1 modeling of material removal rate (mrr) using copper and graphite electrodes in this paper, to study the performance characteristics of the process , two groups of experiments are designed using the kerosene dielectric alone or with graphite powder mixing, each contains (22) experiments for comparing the results produced by edm and pmedm machining. each group was divided in two subgroups. the first subgroup used the copper electrodes, while the graphite electrodes were used in the second subgroup. a new set of w/p and electrode was using in each experiment. the surface roughness (sr), the material removal rate (mrr) and the tool wear ratio (twr), which are experimentally measured and calculated after edm and pmedm machining with the input parameters are modeled by using the response surface methodology (rsm) and the two level factorial (2³) design for both experimental groups. the input edm parameters and their levels are given in table (3), while the output process responses are given in table (4). the designed edm experimental matrix in a random manner with the selected actual factors and the experimental response results for the both groups using the kerosene dielectric or the kerosene dielectric with graphite powder mixing with copper and graphite electrodes are collected in one matrix as given in table (5). the two level factors (2�) full factorial design (ffd) was used to set the necessary number of experiments to fit the model. the anova technique was used to analyze the significance of edm process parameters, where the f-test ratio is calculated for a 95% level of confidence. the anova functions then run in order to assess the results for the material removal rate (mrr) response which are given in table (6) using the two levels and three factor for backward partial sum of squares transform model for lower the p-value. the model f-value of 107.11implies the model is significant. values of "prob> f" less than 0.0500 indicate model terms are significant. in this case, a, b, c, d, ab, bc, bd, cd are significant model terms. the predicted final empirical equation is: material removal rate (mmr) = + 1.886404.63234 * a + 0.66256 * b 0.12830* c 12.03147*d + 0.49159*a*b + 0.018299* b*c+0.79800*b*d+0.078758*c*d …(1) the three dimensional (3d) graphs given in figures (3-6) are used to interpret and evaluate the model for the experimental groups. these figures show the influence of the edm and pmedm parameters on the material removal rate. all figures indicated that material removal rate is increasing with increasing the pulse current (up to 22 a) and the pulse on duration (up to120 µs). figure (3) and table (5) indicated that when using these levels of parameters with the copper electrodes, mrr reaches theoretically (28.2177 mm³/min), and experimentally (30.2452 mm³/min). when using the graphite powder mixing in kerosene dielectric, mrr reaches the value (58.1689 mm³/min), as shown in figure (5) and the experimental value is (58.0063 mm³/min). this means that the process removal rate increase by (206 %) when using the graphite powder compared with when using the kerosene dielectric alone. the same results obtained when working with graphite electrodes and kerosene dielectric alone, where the maximum productivity of the process obtained reaches a value (40.5832 mm³/min) as shown in figure (4), whereas the experimental value is (37.4865 mm³/min). the predicted mrr reaches a value of (70.5344 mm³/min) with the same previous parameters and using the graphite powder mixing in kerosene dielectric as shown in figure (6) and the experimental value is (82.8404 mm³/min), i.e., the predicted mrr process improved by (174 %) and experimentally by (221 %). the total predicted improvement of the mrr process is (250 %); experimentally by (274 %) with respect to using the graphite electrode with graphite powder mixing and compared with the case when using the copper electrodes and the kerosene dielectric alone. this means that productivity increases with the pulse current and pulse on duration time, especially when using the graphite electrodes and graphite powder mixing. the amount of thermal energy generated would be great and it is working to increase the melting and abrasive processing to remove successive more layers of workpiece ahmed n. al-khazraji al-khwarizmi engineering journal, vol. 11, no. 3, p.p. 2036 (2015) 24 surface. this energy will increase with increasing the pulse current period, especially when using the graphite powder mixed in kerosene dielectric, which owns high level of hardness and abrasiveness and working to increase the removal property of the process. the high thermal conductivity of the graphite electrode and the graphite powder also works to increase the amount of thermal energy transformed to the workpiece surface, thereby improving removal and productivity efficiency. the high electrical conductivity of the graphite powder is working to increase the electrical conductivity of the kerosene dielectric and this will improve the discharge characteristics of the process by increase and intensify the arrangement and intensity of discharge energy bands consequently improved the material removal rates. 3.1.1. numerical optimization of material removal rate results for optimization and to development of the predicted model with the best edm and pmedm parameters, a set of new goals for the mrr response will be conducted to generate the optimal combination conditions for these parameters. the new objective function named the desirability will allow evaluating the goals by a proper combining. the main goals are to maximize the values of response with the same ranges of the selected edm parameters and electrodes types as mentioned in table (7). the best three solutions found from the desirability process shows that the optimum predicted values of the mrr obtained when using the graphite electrodes with pulse current about (22 a), pulse of duration about (120 µs) and using the graphite mixed powder gives the best maximum predicted mrr of (70.534mm³/min) with a maximum desirability ratio (0.839) as shown in table (8). the desirability process shows that the best predicting response values are approximately the same with the obtained values by experiments as indicated in table (5), experiments number (28) and (35) with the same input parameters where the experimentally values of mrr obtained are (82.8404) and (74.1234) mm³/min respectively and this confirmation the theoretical results of the present work. table 3, the input edm parameters and their levels for both groups. fac. name units min. max. coded values levels a pulse current (ip) (a) 8 22 -1 +1 2 b pulse on duration (ton) (µs) 40 120 -1 +1 2 c graphite powder mixed in kerosene dielectric g/l 0 5 -1 +1 2 table 4, the edm process responses, mrr, twr and sr. response name units minimum maximum trans model r1 material removal rate(mmr) mm³/min 6.1696 82.8404 none r2fi r2 tool wear ratio(ewr) % 0.4168 12.8845 none r3fi r3 surface roughness (sr) µm 2.77 6.32 inverse r3fi ahmed n. al-khazraji al-khwarizmi engineering journal, vol. 11, no. 3, p.p. 2036 (2015) 25 table 5, the designed experimental matrix for group (1) using copper electrodes. block no. run no. input factors(actual) responses x1 x2 x3 x4 material removal rate (mmr) (mm³/min) tool wear ratio (ewr) (%) surface roughness (sr) (µm) a: type of electrode b: pulse current (ip) (a) c: pulse on duration (ton) (µs) d:graphite powder mixed in kerosene dielectric (g/l) 1 1 copper 22 120 0 26.7538 1.898 5.65 1 2 graphite 8 40 5 7.9017 12.8845 2.78 1 3 graphite 8 120 0 7.2612 3.0141 4.75 1 4 graphite 22 120 0 35.6832 1.5401 5.31 1 5 graphite 8 120 5 7.4974 11.3743 5.36 1 6 graphite 22 40 5 37.1668 4.9357 4.63 1 7 graphite 8 40 0 8.5929 7.0756 2.87 1 8 copper 8 120 0 9.3969 0.4168 3.91 1 9 copper 8 40 5 9.4955 4.396 3.77 1 10 graphite 22 120 5 74.062 1.7828 6.28 1 11 copper 22 40 5 29.5841 5.0271 5.24 1 12 copper 22 40 0 15.9392 6.0467 4.84 1 13 copper 8 120 5 14.2975 1.582 4.88 1 14 copper 22 120 5 55.0778 1.6091 6.19 1 15 copper 8 40 0 6.2369 3.1489 4.05 2 16 copper 22 40 0 15.8625 5.9988 4.85 2 17 graphite 22 120 0 37.4865 1.0934 6.26 2 18 copper 22 120 0 25.8697 1.9535 5.63 2 19 copper 22 120 5 58.0663 1.7499 6.21 2 20 graphite 8 40 0 7.1359 7.0756 2.9 2 21 graphite 22 40 0 29.1021 3.1563 3.78 2 22 copper 8 120 5 14.0783 1.5006 4.92 2 23 graphite 8 40 5 8.1076 12.1329 2.77 2 24 copper 8 40 0 6.8461 2.764 4.07 2 25 graphite 8 120 5 9.0389 8.9295 5.32 2 26 graphite 8 120 0 6.8553 2.9656 4.73 2 27 copper 8 120 0 8.4774 0.5054 3.94 2 28 graphite 22 120 5 82.8404 1.6076 6.32 2 29 copper 8 40 5 7.1469 4.5038 3.81 3 30 graphite 22 40 5 31.4558 5.8591 4.46 3 31 graphite 22 40 0 29.1021 3.1563 3.78 3 32 graphite 8 120 0 6.1696 2.9883 4.77 3 33 copper 8 40 0 7.4271 2.7986 4.09 3 34 copper 8 120 0 9.2215 0.4273 3.94 3 35 graphite 22 120 5 74.1234 1.6262 6.3 3 36 graphite 8 40 0 12.1531 5.7332 2.81 3 37 copper 8 120 5 9.7263 1.5738 4.9 3 38 copper 22 40 5 30.343 5.0822 5.25 3 39 copper 22 120 5 55.9944 1.5594 6.17 3 40 graphite 8 120 5 10.277 8.9295 5.34 3 41 graphite 22 120 0 36.3096 1.376 6.24 3 42 copper 22 120 0 30.2452 1.9765 5.61 3 43 copper 8 40 5 9.6572 4.05 3.79 ahmed n. al-khazraji al-khwarizmi engineering journal, vol. 11, no. 3, p.p. 2036 (2015) 26 table 6, the (anova) analysis for material removal rate (mrr) after the edm. source sum of squares df mean square f value p-value prob> f block 52.40 2 26.20 model 17331.15 8 2166.39 107.11 < 0.0001 significant a-type of electrode 171.34 1 171.34 8.47 0.0065 b-pulse current (ip) 161.21 1 161.21 7.97 0.0081 c-pulse on duration (ton) 209.58 1 209.58 10.36 0.0029 d-graphite powder mixed in kerosene dielectric 667.47 1 667.47 33.00 < 0.0001 ab 500.48 1 500.48 24.75 < 0.0001 bc 1089.99 1 1089.99 53.89 < 0.0001 bd 1299.28 1 1299.28 64.24 < 0.0001 cd 412.07 1 412.07 20.37 < 0.0001 residual 647.20 32 20.23 cor total 18030.76 42 fig. 3. the 3d graphs for mrr using kerosene dielectric alone and copper electrodes fig. 4. the 3d graphs for mrr using kerosene dielectric alone and the graphite electrodes. d: sic powder mixed in kerosene dielectric = 0 40 60 80 100 120 8 10 12 14 16 18 20 22 0 20 40 60 80 100 m at er ia l r em ov al r at e( m m r ) (m m ³/ m in ) b: pulse current (ip) ((a))c: pulse on duration (t on) ((µs)) 40 60 80 100 120 8 10 12 14 16 18 20 22 0 20 40 60 80 100 m at er ia l r em ov al r at e( m m r ) (m m ³/ m in ) b: pulse current (ip) ((a))c: pulse on duration (t on) ((µs)) design-expert® software factor coding: actual material removal rate(mmr) (mm³/min) design points above predicted value design points below predicted value 82.8404 6.1696 x1 = b: pulse current (ip) x2 = c: pulse on duration (t on) actual factors a: type of electrode = copper d: sic powder mixed in kerosene dielectric = 0 design-expert® software factor coding: actual material removal rate(mmr) (mm³/min) design points above predicted value design points below predicted value 82.8404 6.1696 x1 = b: pulse current (ip) x2 = c: pulse on duration (t on) actual factors a: type of electrode = graphite d: sic powder mixed in kerosene dielectric = 0 ahmed n. al-khazraji al-khwarizmi engineering journal, vol. 11, no. 3, p.p. 2036 (2015) 27 fig. 5. the 3d graphs for mrr using kerosene dielectric with graphite powder mixing (pmedm) and the copper electrodes. fig. 6. the 3d graphs for mrr using kerosene dielectric with graphite powder mixing (pmedm) and the graphite electrodes. 3.2 modeling of tool wear ratio using copper and graphite electrodes the anova technique for the tool wear ratio (twr) response which are given in table (9) using the three factor backward levels for transform partial sum of squares model for lower the p value. table 7, the new constraints goals for optimization the mrr of the process. name goal lower limit upper limit lower weight upper weight importance a:type of electrode is in range copper graphite 1 1 3 b:pulse current (ip) is in range 8 22 1 1 3 c:pulse on duration (ton) is in range 40 120 1 1 3 d:graphite powder mixed in kerosene dielectric is in range 0 5 1 1 3 material removal rate(mmr) maximize 6.1696 82.8404 1 1 3 d: sic powder mixed in kerosene dielectric = 5 40 60 80 100 120 8 10 12 14 16 18 20 22 0 20 40 60 80 100 m at er ia l r em ov al r at e( m m r ) (m m ³/ m in ) b: pulse current (ip) ((a))c: pulse on duration (t on) ((µs)) d: sic powder mixed in kerosene dielectric = 5 40 60 80 100 120 8 10 12 14 16 18 20 22 0 20 40 60 80 100 m at er ia l r em ov al r at e( m m r ) (m m ³/ m in ) b: pulse current (ip) ((a))c: pulse on duration (t on) ((µs)) design-expert® software factor coding: actual material removal rate(mmr) (mm³/min) design points above predicted value design points below predicted value 82.8404 6.1696 x1 = b: pulse current (ip) x2 = c: pulse on duration (t on) actual factors a: type of electrode = copper design-expert® software factor coding: actual material removal rate(mmr) (mm³/min) design points above predicted value design points below predicted value 82.8404 6.1696 x1 = b: pulse current (ip) x2 = c: pulse on duration (t on) actual factors a: type of electrode = graphite ahmed n. al-khazraji al-khwarizmi engineering journal, vol. 11, no. 3, p.p. 2036 (2015) 28 table 8, the desirability process for optimization of the predicted mrr. no. type of electrode pulse current (ip) (a) pulse on duration (t on) (µs) sic powder mixed in kerosene dielectric gm/l material removal rate (mmr) mm³/min desirability 1 graphite 22.000 120.000 5 70.534 0.839 selected 2 graphite 22.000 119.162 5 70.239 0.836 3 graphite 21.860 120.000 5 69.954 0.832 the model f-value of 139.45 implies the model is significant. values of "prob> f" less than 0.0500 indicate model terms are significant. in this case, a, b, c, d, ab, ad, bd, abc, abd are significant model terms. the predicted final case, equation is: tool wear ratio (twr)= + 9.29683 + 5.42634 * a 0.13523 * b -0.038354*c + 2.92512*d0.28365 * a * b 9.40295 e-003 *a + 1.77480 * a* d 0.12766 * b * d + 6.81399 e – 004 * a * b * c0.062467 * a * b * d …(2) the three dimensional (3d) graphs given in figures (7 10) show the influence the edm and pmedm parameters on the tool wear ratio. figure (7) indicates that when using the pulse current (8 a) and pulse on duration (40 µs), the tool wear ratio decreased, reaching the values (3.05%) when using the copper electrodes and kerosene dielectric alone and (3.68%) when using the graphite electrodes and the kerosene dielectric alone with pulse current (22 a), as shown in figure (8). figure (9) depicts the 3d graphs for twr using the pulse current (8 a) and pulse on duration (120 µs), and the minimum tool wear ratio obtained when using the copper electrodes and the kerosene dielectric alone reaches the values (0.31%) and (1.05%) when using the graphite electrodes with pulse current (22 a), pulse on duration (120 µs) and the kerosene dielectric, as shown in figure (9) and (10), respectively. the main conclusion of the twr calculation process is that the best minimum value obtained when using the pulse current (8 a), the pulse on duration (120 µs), the copper electrode and the kerosene dielectric alone reaches the values (0.31 %) and experimentally reaches the values (0.42 %). in all cases, the use of abrasive powder mixing like graphite increases the tool wear ratio but at the same time increasing the material removal rates up to (271%) as indicated in table (5), experiment (28) comparing with experiments (1, 18 and 42) which given the best mrr values with the same high levels of input parameters, but with copper electrodes and without using the graphite powder mixing. the use of short pulse on time duration of (40 µs) and the low values of the used pulse current (8 a) will reduce the electrode wear ratio to its middle levels specially when using the kerosene dielectric alone. these wear levels are highly increasing when use the graphite electrodes and graphite powder mixing with the dielectric, because the efficiency of the material removal rates will be increasing due to high electrical and thermal conductivities as well as abrasive properties of graphite powder and the low density of graphite electrodes, where removal process will work efficiently even with low levels of thermal energy generated. the use of high current for a short time slightly increasing the tool wear ratio and the use of powder mixing improving the performance specially with using of graphite electrodes which will give a better wear ratios than with copper for both cases of using or not the graphite powder mixing because it transmits the generated heat away by increase the gap distance between the tool and the workpiece, because the addition of graphite powder to dielectric fluid would cause an increase in the electrical conductivity of the fluid thereby increasing the gap and then the abrasive and erosive processes will be working at a longer distance from the electrode surfaces. these tool wear ratios highly decrease with increasing the duration of pulse current time at the same values of used pulse current as shown in figures (9) and (10). these ratios are decreases to its minimum levels for all cases as indicated in figure(9), especially when using the kerosene dielectric alone specially when using the copper electrodes due to its high density as well as because the thermal conductivity of copper is less than graphite material which reduces the transition of thermal energy generated by the dielectric and this will reduce the ratio of carbon atoms interact with the electrode surface which is the main reason ahmed n. al-khazraji al-khwarizmi engineering journal, vol. 11, no. 3, p.p. 2036 (2015) 29 to its wear. these minimum twr levels will allow to working with longer machining times for a greater amount of metal removal with the minimum electrode wear. it also allows access to the best accuracy for parts, especially when machining parts of large depths by using the same elect rode without the need to be replaced, because the tool can maintain its original form for the longest period with these few percentage of wear ratios. 3.2.1 numerical optimization of tool wear ratio results for optimization the predicted model with the best edm and pmedm parameters, the desirability for minimize the values of response with the same ranges of the selected edm parameters and electrodes types, as mentioned in table (10). the best solution founded from the desirability process shows that the optimum predicted values of the twr when using the copper electrodes with pulse current (8.186 a), pulse of duration is (118.875 µs) and using the kerosene dielectric alone gives the best minimum predicted twr of (0.364%) with a maximum desirability ratio (1.000). the desirability process reveals that the best predicting response values are approximately the same to the obtained values by experiments, and this confirms the results obtained experimentally. table (10) indicated also that the use of graphite electrodes with pulse current (22 a), pulse of duration (120 µs) and using the kerosene dielectric alone gives also a good minimum predicted value of twr of (1.059%) with a maximum desirability ratio (0.949). table 9, the (anova) analysis for material removal rate (twr) after the edm. source sum of squares df mean square f value p-value prob> f block 8.52 2 4.26 model 399.00 10 39.90 139.45 < 0.0001 significant a-type of electrode 43.82 1 43.82 153.14 < 0.0001 b-pulse current (ip) 37.82 1 37.82 132.20 < 0.0001 c-pulse on duration (ton) 98.54 1 98.54 344.40 < 0.0001 dgraphite powder mixed in kerosene dielectric 67.99 1 67.99 237.63 < 0.0001 ab 29.12 1 29.12 101.79 < 0.0001 ac 1.12 1 1.12 3.91 0.0572 ad 25.22 1 25.22 88.14 < 0.0001 bd 33.43 1 33.43 116.85 < 0.0001 abc 1.50 1 1.50 5.24 0.0293 abd 8.13 1 8.13 28.43 < 0.0001 residual 8.58 30 0.29 cor total 416.10 42 fig. 7. the 3d graphs for twr using the pulse current (8 a) and pulse on duration (40 µs). design points below predicted value x2 = d: sic powder mixed in kerosene dielectric 0 5 copper graphite 0 2 4 6 8 10 12 14 t oo l w ea r ra tio (e w r ) (% ) a: type of electrode (-) d:graphite powder mixed in kerosene dielectric (g/l) design-expert® software factor coding: actual tool wear ratio(ewr) (%) design points above predicted value design points below predicted value x1 = a: type of electrode x2 = d: sic powder mixed in kerosene dielectric actual factors b: pulse current (ip) = 8 c: pulse on duration (t on) = 40 t oo l w ea r ra tio (e w r ) (% ) ahmed n. al-khazraji al-khwarizmi engineering journal, vol. 11, no. 3, p.p. 2036 (2015) 30 fig. 8. the 3d graphs for twr using the pulse current (22 a) and pulse on duration (40 µs). fig. 9. the 3d graphs for twr using the pulse current (8 a) and pulse on duration (120 µs). fig. 10. the 3d graphs for twr using the pulse current (22 a) and pulse on duration (120 µs). table 10, the desirability process for optimization of the predicted twr. x2 = d: sic powder mixed in kerosene dielectric 0 5 copper graphite 0 2 4 6 8 10 12 14 t oo l w ea r ra tio (e w r ) (% ) a: type of electrode (-) d:graphite powder mixed in kerosene dielectric (g/l) x2 = d: sic powder mixed in kerosene dielectric 0 5 copper graphite 0 2 4 6 8 10 12 14 t oo l w ea r ra tio (e w r ) (% ) a: type of electrode (-) d:graphite powder mixed in kerosene dielectric (g/l) design points below predicted value x2 = d: sic powder mixed in kerosene dielectric 0 5 copper graphite 0 2 4 6 8 10 12 14 t oo l w ea r ra tio (e w r ) (% ) a: type of electrode (-) d:graphite powder mixed in kerosene dielectric (g/l) no. type of electrode pulse current (ip) (a) pulse on duration (ton) (µs) sic powder mixed in kerosene dielectric (gm/l) tool wear ratio (ewr) (%) desirability 1 copper 8.186 118.875 0 0.364 1.000 selected 37 graphite 22.000 120.000 0 1.059 0.949 design-expert® software factor coding: actual tool wear ratio(ewr) (%) design points above predicted value design points below predicted value x1 = a: type of electrode x2 = d: sic powder mixed in kerosene dielectric actual factors b: pulse current (ip) = 22 c: pulse on duration (t on) = 40 t oo l w ea r ra tio (e w r ) (% ) design-expert® software factor coding: actual tool wear ratio(ewr) (%) design points above predicted value design points below predicted value x1 = a: type of electrode x2 = d: sic powder mixed in kerosene dielectric actual factors b: pulse current (ip) = 8 c: pulse on duration (t on) = 120 t oo l w ea r ra tio (e w r ) (% ) design-expert® software factor coding: actual tool wear ratio(ewr) (%) design points above predicted value design points below predicted value x1 = a: type of electrode x2 = d: sic powder mixed in kerosene dielectric actual factors b: pulse current (ip) = 22 c: pulse on duration (t on) = 120 ahmed n. al-khazraji al-khwarizmi engineering journal, vol. 11, no. 3, p.p. 2036 (2015) 31 3.3 modeling of surface roughness using copper and graphite electrodes the anova technique for the surface roughness (sr) response which are given in table(11) using the three factor backward levels for transform inverse and partial sum of squares model for lower the p-value. the model f-value of 461.55 implies the model is significant. values of "prob> f" less than 0.0500 indicate model terms are significant. in this case, a, b, c, d, ab, ac, bc, bd, cd, abc, abd, acd, bcd are significant model terms. the predicted final empirical equation is: 1/(surface roughness (sr)) = + 0.40985 +0.11090 * a 7.40310 e –003 * b – 1.40639 e-003 * c + 0.043313 * d 3.47700e-003 * a* b1.10998e–003 * a * c + 3.35689e-005 * b *c-2.87530e-003*b*d-5.70120e*d+ 3.63772 e005*a*b*c-4.80040e-004*a*b*d+9.13928 e005*a*c*d+3.09331e-005*b*c*d …(3) the three dimensional (3d) graphs given in figures (11 14) show the influence of the edm and pmedm parameters on the surface roughness. as shown in these figures, the minimum surface roughness (sr) values obtained when using the pulse current (8 a) and pulse on duration (40 µs) in all cases of the designed experimental groups. figure (11) indicates that when using the copper electrodes and the kerosene dielectric alone, the minimum surface roughness reduced to (4.0470 µm), experimentally (3.91 µm). when using the graphite electrodes figure (13), the minimum surface roughness reduced to values (2.8723 µm), experimentally (2.81 µm). this means that the surface roughness improved by (139 %) because the graphite powder mixing owns a high electrical conductivity which will working on increasing the dielectric electrical conductivity and consequently the gap distance increases, then the pressurized dielectric from both sides will remove the new fine removal layers from the surface of the workpiece and take them to the outside of the gap area combining operation of evaporation and melting leaving a fine surface quality. figure (12) and (14) show the 3d graphs for sr using the copper and graphite electrodes and graphite powder mixed with kerosene dielectric, where the minimum surface roughness reaches the values (3.8128 µm) and (2.7579 µm) respectively, experimentally with values (3.77 µm) and (2.77 µm), respectively. this means that the overall predicted minimum sr for all experiments runs obtained when working with graphite electrodes, the pulse current (8 a), the pulse on duration (40.µs) and kerosene dielectric mixed with graphite powder with (2.76µm) value, experimentally (2.77 µm), i.e., the process improved by (139 %), while experimentally improved by (141 %). in general, it is better to use the graphite electrodes because it's thermal and electrical conductivity are less than copper materials in many levels, thus it will produce a little value of discharge energy works to minimize the defects resulting from increased discharge energy such as electromechanical pits and decay formation which keeps the producing surfaces with higher quality and fine roughness. the use of graphite electrodes gives better surface roughness when using low pulse current levels for a small period of time, because the abrasion process cannot accomplish its work completely due to the little amount of thermal energy necessary for melting the surface layer of workpiece, and thus the abrasive phenomenon will be works with less abilities required to remove the surface layers as well as the lack of interactions required for the generation of new carbides due to low level of energy generated. the formation of a molten layer that freezes on the surface which is of better roughness than the erosive surfaces. ahmed n. al-khazraji al-khwarizmi engineering journal, vol. 11, no. 3, p.p. 2036 (2015) 32 table 11, the (anova) analysis for (sr) after the edm. source sum of squares df mean square f value p-value prob> f block 7.328e-004 2 3.664e-004 model 0.14 13 0.011 461.55 < 0.0001 significant a-type of electrode 0.018 1 0.018 756.53 < 0.0001 b-pulse current (ip) 0.020 1 0.020 830.94 < 0.0001 c-pulse on duration (ton) 0.025 1 0.025 1039.58 < 0.0001 d-graphite powder mixed in kerosene dielectric 2.766e-003 1 2.766e-003 114.75 < 0.0001 ab 4.366e-003 1 4.366e-003 181.13 < 0.0001 ac 0.016 1 0.016 645.36 < 0.0001 bc 3.657e-003 1 3.657e-003 151.72 < 0.0001 bd 2.926e-003 1 2.926e-003 121.39 < 0.0001 cd 4.091e-003 1 4.091e-003 169.70 < 0.0001 abc 4.263e-003 1 4.263e-003 176.87 < 0.0001 abd 7.877e-004 1 7.877e-004 32.68 < 0.0001 acd 9.709e-004 1 9.709e-004 40.28 < 0.0001 bcd 3.044e-003 1 3.044e-003 126.30 < 0.0001 residual 6.508e-004 27 2.410e-005 cor total 0.15 42 fig. 11. the 3d graphs for sr using the copper electrodes and kerosene dielectric alone. fig. 12. the 3d graphs for sr using the copper electrodes and (5g/l) graphite powder mixing in kerosene dielectric d: sic powder mixed in kerosene dielectric = 0 40 60 80 100 120 8 10 12 14 16 18 20 22 2 3 4 5 6 7 s ur fa ce r ou gh ne ss ( s r ) (µ m ) b: pulse current (ip) ((a))c: pulse on duration (t on) ((µs)) 40 60 80 100 120 8 10 12 14 16 18 20 22 2 3 4 5 6 7 s ur fa ce r ou gh ne ss ( s r ) (µ m ) b: pulse current (ip) ((a))c: pulse on duration (t on) ((µs)) design-expert® software factor coding: actual original scale surface roughness (sr) (µm) design points above predicted value design points below predicted value 6.32 2.77 x1 = b: pulse current (ip) x2 = c: pulse on duration (t on) actual factors a: type of electrode = copper design-expert® software factor coding: actual original scale surface roughness (sr) (µm) design points above predicted value design points below predicted value 6.32 2.77 x1 = b: pulse current (ip) x2 = c: pulse on duration (t on) actual factors a: type of electrode = copper d: sic powder mixed in kerosene dielectric = 5 ahmed n. al-khazraji al-khwarizmi engineering journal, vol. 11, no. 3, p.p. 2036 (2015) 33 fig. 13. the 3d graphs for sr using the graphite electrodes and kerosene dielectric alone. fig. 14. the 3d graphs for sr using the the graphite and (5g/l) graphite powder mixing in kerosene dielectric. 3.3.1. numerical optimization of surface roughness results for optimization the predicted model with the best edm and pmedm parameters, the desirability for minimize the values of response with the same ranges of the selected edm parameters and electrodes types as mentioned in table (12). the best sr when using the graphite electrodes with pulse solution founded from the desirability process shows that the optimization predicted values of the current (8.009 a), pulse of duration about (40.408 µs) and using the kerosene dielectric with graphite powder mixed gives the best minimum predicted sr of (2.765 µm) with a maximum desirability ratio (1.000). the desirability process exhibits that the best predicting response values are approximately the same with the obtained values by experiments (2.77 µm), with a difference less than (0.015 µm), and this confirms the results obtained experimentally. table 12, the desirability process for optimization of the predicted sr. number type of electrode pulse current (ip) pulse on duration (t on) sic powder mixed in kerosene dielectric surface roughness (sr) desirability 1 graphite 8.009 40.408 5 2.765 1.000 selected 2 graphite 8.045 40.038 5 2.762 1.000 3 graphite 8.063 40.401 5 2.769 1.000 40 60 80 100 120 8 10 12 14 16 18 20 22 2 3 4 5 6 7 s ur fa ce r ou gh ne ss ( s r ) (µ m ) b: pulse current (ip) ((a))c: pulse on duration (t on) ((µs)) d: sic powder mixed in kerosene dielectric = 5 40 60 80 100 120 8 10 12 14 16 18 20 22 2 3 4 5 6 7 s ur fa ce r ou gh ne ss ( s r ) (µ m ) b: pulse current (ip) ((a))c: pulse on duration (t on) ((µs)) design-expert® software factor coding: actual original scale surface roughness (sr) (µm) design points above predicted value design points below predicted value 6.32 2.77 x1 = b: pulse current (ip) x2 = c: pulse on duration (t on) actual factors a: type of electrode = graphite d: sic powder mixed in kerosene dielectric = 0 design-expert® software factor coding: actual original scale surface roughness (sr) (µm) design points above predicted value design points below predicted value 6.32 2.77 x1 = b: pulse current (ip) x2 = c: pulse on duration (t on) actual factors a: type of electrode = graphite d: sic powder mixed in kerosene dielectric = 5 ahmed n. al-khazraji al-khwarizmi engineering journal, vol. 11, no. 3, p.p. 2036 (2015) 34 4. conclusions the main conclusions obtained can be summarized in the following: 1the best results for the productivity of the process (mrr) obtained when using the graphite electrodes, the pulse current (22 a), the pulse on duration (120 µs) and using the graphite powder mixing in kerosene dielectric reaches (82.84 mm³/min).this result gives an improvement in the material removal rate by (274%) with respect to the corresponding value obtained when using the copper electrodes with kerosene dielectric alone. 2the best results for the tool wear ratio (twr) of the process obtained when using the copper electrodes, the pulse current (8 a), the pulse on duration (120 µs) and using the kerosene dielectric alone reaches (0.31 %). 3the use of graphite electrodes, the kerosene dielectric with graphite powder mixing, the pulse current (8 a) and the pulse on duration (40 µs) gives the best surface roughness (sr) of a value (2.77 µm). this result yields an improvement in sr by (141%) compared with using the corresponding value obtained when using copper electrodes, the kerosene dielectric alone and the same other parameters and machining conditions. the desirability process showed that the best predicting response values are approximately the same as to those obtained values by experiments, as mentioned in the three above items, and this confirms the results of the present work. nomenclature anova analysis of variance ccd central composite design cnc computer numerical control edm electric discharge machining ffd full factorial design ip pulse current (a) mrr material removal rate (mm³/min) pmedm powder mixing electric discharge machining rsm 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[13] singh s., maheshwari s., and pandey p.,” some investigations into the electric – discharge machining of hardened tool steel using different electrode materials”, journal of materials processing technology, 149, (1-3), pp. 272–277, 2004. [14] reddy s. and c. s. rao," design of experiments based grey relational analysis in various machining processes, a review ”, research journal of engineering sciences, issn 2278 – 9472, vol. 2, (1), pp. 21-26, 2013. [15] saurav d. and siba sankar m.,” modeling, simulation and parametric optimization of wire edm process using response surface methodology coupled with grey-taguchi technique”, international journal of engineering, science and technology, vol. 2, no. 5, pp. 162-183, 2010. [16] b. reddy, g .n. kumar and k. chandrashekar,“ experimental investigation on process performance of powder mixed electric discharge machining of aisi d3 steel and en-31 steel”, international journal of current engineering and technology, vol. 4, no. 3, 2014. [17] astm a681, “standard specification for tool steels alloy”, american society for testing and materials, washington, d.c., 1976. [18] astm a370,“standard test method and definitions for mechanical testing of steel products”,american society for testing and materials,washington, d.c., 1977. )2015( 2036، ���� 3، ا�� د11 ا���ارز� ا��� �� ا������� � ا��د �� ف ا��زر�� 36 � ن��ج�و درا ���� � ��!"#� �3"!2ا� 0�1 ا���/وج ا���ا-�, �+��قا�(&)�' #"�&�ارة ا�$� �+�!� ������� ا� �1 ا��4 *** � ����د �1 ��� ** *ا�7 ن"56 ا��/رج ����������/ ()' ا!&%$#� ا! *+!+%�ا!/�.-� ا!, **،* �� / 2345ء*�.-� ������()' ا!&%$#� ا! *** dr_ahmed53 @yahoo.com: 8!647$ اا��,4و!: * alrabiee2002@yahoo.com: 8!647$ اا��,4و!: ** smaengg@yahoo.com: 8!647$ اا��,4و!: *** ا����8 �4 $را#;;�3 ا!7?;;< اھ;;>6-%;;8 ab;;c ق+?;;(. e;;�f4ويا! ا!/4ا;;���4و#;;�;;. l�i;; 8;;fjkوج ا! ��;;� -;;�زلا! ا!k�34&5 2ل;;o p�q;;r,!ا �;;�s tjuv!�;;3 ;;3 w64x,!� 8k�34&���و ا!�34+ن t�pmedm ( zs[ juv!8!( )?+قا! j.yso ا!!�t 4وم��+ع ا! d2 . 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(8u-6 p`fأ ��+ro ?u#�� ��4و ٢.٧٧( ,&�(��/�ا!، وھ>ا ).,4.,% 8u-c 8;f �%(?c �;.+-� iu(!�7 ) ٪١٤١(3%)�7 ا(�!�&�st ل+k?!ا 'c 8,!ا � �vs �.$%t ل�ا#, 'cب�u)س أ�و ا!%?jk�. l��4و#��x;~ ا! ; .;t+ j;$ه! -;�زلا! ا!o$2وا!�;4وف ات �p ا�4oى qr,s!. 102-110 al-khwarizmi engineering journal,vol. 12, no. comparative study of between spark ignition engine compression ignition engine department (received http://dx.doi.org/10.22153/kej.2016.06.003 abstract many researchers consider homogeneous charge compression ignition (hcci) engine mode as a promising alternative to combustion in spark ignition and compression ignition engines. the hcci engine runs on lean mixtures of fuel and air, and the combustion is produce mode was investigated in this paper. a variable compression ratio, spark ignition engine type td110 was used in the experiments. the tested fuel was iraqi conventional gasoli the results showed that hcci engine can run in very lean equivalence ratios. the brake specific fuel consumption was reduced about 28% compared with a spark ignition engine. the experimental tests showed that the emissions concentrations were reduced by 91.27% for nox, 85.99% for co, 78.91% for co hydrocarbons compared to the si engine. hcci engine produced little noise with about 26.68% less than si engine keywords: homogeneous charge compression ignition, hcci, 1. introduction the homogeneous charge compression ignition system (hcci) can be considered as system with low emitted emissions, but lower efficiency compared to conventional engines. the hcci engine emits low nox emissions, virtually no particulate matters (pm) emissions. however, the marketing of hcci technology still represents a huge challenge because of the narrow field of operation and the difficulties associated with the combustion phase [1]. the hcci depends on the homogeneous mixture of the fuel by fuel and air before combustion starts and that th mixture is auto-ignited due to the temperatures of the compression stroke hcci system is similar to si system systems use a premixed charge. in the same time hcci system is similar to ci system khwarizmi engineering journal,vol. 12, no. 4, p.p. 102110 (2016) of performance and emission characteristics spark ignition engine and homogeneous charge compression ignition engine (hcci) nahedh mahmood ali department of materials engineering / university of technology email: nahidh.mahmood60@gmail.com (received 25 january 2016; accepted 15 june 2016) http://dx.doi.org/10.22153/kej.2016.06.003 many researchers consider homogeneous charge compression ignition (hcci) engine mode as a promising alternative to combustion in spark ignition and compression ignition engines. the hcci engine runs on lean mixtures roduced from the fuel autoignition instead of ignited by a spark investigated in this paper. a variable compression ratio, spark ignition engine type td110 was used in the the tested fuel was iraqi conventional gasoline (on=82). the results showed that hcci engine can run in very lean equivalence ratios. the brake specific fuel consumption reduced about 28% compared with a spark ignition engine. the experimental tests showed that the emissions reduced by 91.27% for nox, 85.99% for co, 78.91% for co2, and 83.56% for unburned hydrocarbons compared to the si engine. hcci engine produced little noise with about 26.68% less than si engine homogeneous charge compression ignition, hcci, gasoline fuel, auto-ignition and combustion the homogeneous charge compression ignition as an attractive system with low emitted emissions, but lower efficiency compared to conventional engines. the hcci engine emits low nox emissions, and virtually no particulate matters (pm) emissions. however, the marketing of hcci technology still represents a huge challenge because of the narrow field of operation and the difficulties associated attain of a by mixing the before combustion starts and that this ignited due to the high the compression stroke [2]. the system as both in the same time, system as both systems are auto-ignited however, the hcci combustion process totally from the two types when the mixture is compressed, temperature and pressure increase. when the timing is controlled successfully, the mixture auto-ignites at a couple of degrees before tdc. the combustion starts at many locations simultaneously [4]. after ignition, the gas that burned first will expand and thereby compre part of the gas that did not burn yet. this compression, together with the overall rise in temperature and the time necessary for the chemical kinetics to start, leads to auto the rest of the mixture. hcci combustion has thus no flame propagation [5]. as far as the mixture preparation is concerned, one approach is port-injection, leading homogeneous charge as in the si engine. another al-khwarizmi engineering journal (2016) emission characteristics homogeneous charge university of technology many researchers consider homogeneous charge compression ignition (hcci) engine mode as a promising alternative to combustion in spark ignition and compression ignition engines. the hcci engine runs on lean mixtures ignited by a spark. this combustion investigated in this paper. a variable compression ratio, spark ignition engine type td110 was used in the the results showed that hcci engine can run in very lean equivalence ratios. the brake specific fuel consumption reduced about 28% compared with a spark ignition engine. the experimental tests showed that the emissions , and 83.56% for unburned hydrocarbons compared to the si engine. hcci engine produced little noise with about 26.68% less than si engine. ignition and combustion. to initiate combustion. combustion process varies [3]. when the mixture is compressed, its pressure increase. when the timing is controlled successfully, the mixture ignites at a couple of degrees before tdc. the combustion starts at many locations . after ignition, the gas that burned first will expand and thereby compress the part of the gas that did not burn yet. this compression, together with the overall rise in temperature and the time necessary for the chemical kinetics to start, leads to auto-ignition of the rest of the mixture. hcci combustion has thus as far as the mixture preparation is concerned, injection, leading to a nearly homogeneous charge as in the si engine. another nahedh mahmood ali al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 102110 (2016) 103 one is a direct injection (di), in which the fuel can be injected very early in the compression stroke or a later stage under very high pressure. the aim of both methods is to obtain an almost homogeneous charge [6]. the hcci engine has no direct means to control the timing of ignition, unlike the si and ci engines. the si engine has ignition timing, and ci diesel cycle engine has a fuel injection beginning, and both are controlling directly the start of combustion [7]. however, in the hcci engine, the ignition is controlled by controlling the conditions of the charge and the cylinder walls at a time when the intake valve closes. the ignition control is one of the biggest challenges with the practical implementation of hcci engine technology [8]. the ignition timing cannot be controlled only indirectly through adjustments in the preparation of the cylinder charge [9]. the most common technological means to facilitate the self-ignition are: 1increasing the compression ratio [9]. 2using intake air heating [10]. 3trapping a high residual gas fraction (rgf) by some method that can alter valve timing and/or lift (e.g. variable valve timing (vvt), electronic valve control (evc)) [11]. 4running the engine on mixtures of fuel with different reactivates and control each fuel fraction [12]. at present, several problems are blocking the road to successful integration of the hcci concept in automotive applications: complex and expensive solutions (e.g. variable valve train systems) may be necessary to make hcci combustion possible and the operating window of smooth hcci operation is still of limited size. however, the most serious problem is the difficulty to control the moment of auto-ignition and the energy release rate. as the mixture in the cylinder is premixed, and no spark plug is used, the chemical processes determine the onset of auto-ignition, as well as the fuel burn rate [13]. çınar et al. studied the effect of variable equivalence ratios and constant intake air temperature of 80 °c on hcci engine operation experimentally. two strategies were used in the study to obtain exhaust gas trapping and hcci operation. the study findings showed that incylinder pressure and heat release rate decreased using, and more residual gases were trapped. the indicated thermal efficiency increased at 1000 rpm engine speed and stoichiometric air/fuel ratio [14]. zhao reported that eliminating the local rich air–fuel mixtures and reduced combustion temperature in hcci operation mode enable to decrease the pm and nox emissions trade off without affecting the high thermal efficiency [15] uyumaz conducted an experimental study to determine the impact of several blends of nheptane-gasoline on hcci combustion mode in four stroke port injection ricardo hydra test engine. the investigation was carried out at a constant engine speed of 1500 rpm and ʎ = 2. the tests examined the impact of inlet air temperature on hcci combustion. the study results clarified that increasing the inlet air temperature forced the start of combustion to advance with all the tested blends. the results revealed that co emissions decreased, and co2 levels increased with the increase of inlet air temperature, due to better oxidization. the maximum measured co emissions were 0.144% (vol.) with b40 (40% nheptane and 60% gasoline), 0.138% (vol.) with b30 (30% n-heptane and 70% gasoline) at 313 k inlet air temperature. hc emissions decreased with increasing the inlet air temperature due to rapid combustion that caused an improvement in chemical reactions at high inlet air temperatures. the maximum measured hc concentrations were 440 ppm and 438.88 for b30 blend at 313 k, and 333 k inlet air temperatures respectively. the study indicated that nox levels were near zero at high combustion temperatures, due to the low temperature of combustion. at high inlet air temperatures, the measured no concentrations were about 1 to 2 ppm [16]. the goal of this work is to compare practically between two combustion systems, (spark ignition engine and hcci engine). the comparison will be for limited engine conditions; which were 1500 rpm engine speed, and full load operation. the engine speed of 1500 rpm was selected as it is relevance to a car's engine runs in city streets. the full load operation was chosen to examine the maximum operation limit before knock limit. 2. experimental set up this study was carried out using a single cylinder, four strokes, and variable compression ratio, spark ignition engine and speed, type td110, using hydraulic dynamometer, fig. 1 illustrates the engine rig and the measuring instruments. table 1 gives this engine specification. the engine was adjusted to overcome limitations in power output by making it full open throttle and adjusting the spark timing to be the optimum one for every operating condition. the nahedh mahmood ali al engine was also modified to use hcci combustion mode by conversion conventional diesel combustion at high loads (with early injection). no manipulation in the architecture of the diesel combustion system. it was kept as it is: – direct injection; – flat cylinder head. fig. 1. the engine rig and the measuring instruments table 1, engine specifications referring to the study of the different hcci concepts, the use of an early injection strategy was chosen. the dilemma with this method is how to avoid the collision of the fuel with the combustion chamber wall. therefore, the point of this concept is to use a narrow the spray cone (less than 100 degrees) to reduce fuel collision with the wall of the combustion chamber and to improve the fuel-air there is considerable flexibility in the area of injection. the common rail fuel injection system name plate varicomp type (gr06/000/037a) the manufacturing year engine type strokes numbers 4 strokes piston diameter stroke swept volume 541 c.c compression ratio max. power output 4 kw at 2800 rpm max. rpm 3600 r.p.m inlet. valve open 54º btdc inlet valve closed 22º atdc exhaust valve open 22º btdc exhaust valve closed 54º btdc al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 104 engine was also modified to use hcci combustion mode by conversion conventional esel combustion at high loads (with early no manipulation in the general architecture of the diesel combustion system. it engine rig and the measuring to the study of the different hcci an early injection strategy with this method is how to avoid the collision of the fuel with the combustion chamber wall. therefore, the primary point of this concept is to use a narrow-angle of the spray cone (less than 100 degrees) to reduce ith the wall of the combustion air mixing, while flexibility in the area of the injection. the common rail fuel injection system has been selected because of the continuous increase in its flexibility. however, the early injection can cause advanced ignition timing and knock can be a problem. the compression ratio was investigated starting from cr=12 at full load operational cases (full load means any more load will cause knock). the nitrogen oxides (nox), unburned hydrocarbon ubhc, co2 were measured by multi emissions analyzer. this device was calibrated at central organization for standardization and quality control in baghdad. the engine noise (o measured by a precision sound level meter equipped with microphone type 4615 was calibrated by standard pisto-phone 4220. the equivalence ratio which the measured air and fuel flow rates to the engine, defined as [14]: ∅ � actual fuel/air ratio stoichiometric fuel/ the following equations used to calculate the engine performance parameters 1brake power �� � ��∗�∗� ��∗���� �� 2fuel mass flow rate �� � !"#��$% ���� # &" '()* �+ 3volumetric efficiency �� ,,,.'. � ��012∗�.34 5��� # �� ,6782. � 9:.; # � ��∗� # <!=>. � )� ?,?@6. )� ?6782. 4brake specific fuel consumption �abc � )� " de # 3600 ij ik 5total fuel heat l' � �� # mn9 �� 6the lost power to overcome the friction (friction power): be � �#� 5o3.��p 7mechanical efficiency: <) � dq rq � dq dqs q varicomp type (gr06/000/037a) 1998 td110 4 strokes 90 mm 85 mm 541 c.c 4-17.5 kw at 2800 rpm 3600 r.p.m 54º btdc 22º atdc 22º btdc 54º btdc arizmi engineering journal, vol. 12, no. 4, p.p. 102110 (2016) has been selected because of the continuous however, the early injection can cause advanced ignition timing and knock. therefore, it he compression ratio effect starting from cr=12:1 to 14.5:1 full load operational cases (full load concept means any more load will cause knock). nitrogen oxides (nox), unburned 2, and co concentration multi -gas mode 4880 analyzer. this device was calibrated at central organization for standardization and ity control in baghdad. the engine noise (overall sound pressure) precision sound level meter microphone type 4615; the device standard calibrator meter type the equivalence ratio which determined from the measured air and fuel flow rates to the engine, ratio air ratio the following equations used to calculate the engine performance parameters [14]: …. (1) �+ atcu …. (2) v,(w ij :*. …. (3) # v,(w ij :*. …. (4) …. (5) consumption ij ik.1w …. (6) …. (7) the lost power to overcome the friction …. (8) mechanical efficiency: …. (9) nahedh mahmood ali al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 102110 (2016) 105 8brake thermal efficiency <d'1. = de x6 × 100 % …. (10) tests procedure after running the engine for a warming period to achieve engine steady state conditions as the oil temperature is at 70 oc±5, and cooling water temperature is at 70 oc±5, the experiments were carried out. the engine design and operating parameters have been varied at the following levels: 1. type of fuel included pure gasoline fuel (base case as a normal spark ignition engine). 2. the engine load varied from no load to full load. 3. the fuel injection timing ranged from 10 to 45 o btdc in steps of 5o. 4. the engine speed fixed at 1500 rpm. in the first tests set, the engine operated in the spark ignition mode. tests of engine performance and exhaust emissions were conducted as a basis for comparison. the engine was run at no load condition, and its speed was adjusted to 1500 rpm ± 20 rpm. the engine operated at a constant speed, and then it was gradually loaded. the experiments conducted at maximum load levels. the engine left running for a period of not less than three minutes for each load condition to confirm the operation stability, and then each test was replicated three times to ensure the tests repeatability. 3. results and discussion fig. 2 indicates that brake power (bp) increases with increasing compression ratio until it reaches it maximum value, which is called the higher useful compression ratio (hucr). the hucr for the gasoline engine is 8:1 as the results clarified. any further increase in compression ratio led to high pressure rates and abnormal combustion (knock) that forced to reduce the engine load highly. fig. 2. compression ratio effect on brake power for wide range of equivalence ratios of gasoline fuel. the hucr for hcci engine was 14:1, as fig. 3 shows. the resulted hcci engine higher useful compression ratio confirms what many researches about the suitable compression ratio for hcci engine. these studies pointed to have a moderate compression ratio to control the better start of combustion [2, 5, 6 & 12]. fig 4 compares the resulted bp at hucr for the two studied modes. hcci engines operated in very lean mixture lied between (ø= 0.2 to 0.7) while gasoline started from ø=0.8. the reduction in brake power for the hcci mode was 6% compared to si mode. also, the resulted bp at very lean equivalence ratio for hcci mode was high, due to higher compression ratio. the equivalence ratio affects both fuel concentration and oxygen concentration. however, since hcci engines operate at lean equivalence ratios; the equivalence ratio has a stronger influence on fuel level than on oxygen concentration. the increasing of the equivalence ratio means increasing the fuel concentration, which results in higher reaction rate and higher brake power. fig. 3. compression ratio effect on brake power for wide range of equivalence ratios for hcci engine. nahedh mahmood ali al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 102110 (2016) 106 fig. 4. bp of the two systems at hucr for each one for wide range of equivalence ratio. brake specific fuel consumption (bsfc) for hcci engine reduced about 28.35% from gasoline engine’s bsfc, as fig. 5 indicates. the lean operation reduces the fuel consumption while preserves the resulted power high. for comparison purposes, the relationship between the bp and the bsfc for the two engines was plotted as in the fig. 6. the brake specific fuel consumption of the hcci engine was less at equal brake powers of the both engines, which means better combustion and fewer engine losses in hcci mode. the lean mixture combustion produces lower exhaust gas temperatures compared to richer mixtures. as fig. 7 shows hcci engine produced lower exhaust gas temperature compared with the si engine. fig. 5. bsfc of the two systems at hucr for each one for wide range of equivalence ratio. fig. 6. the bsfc for variable bp of the two systems at hucr for each one. fig. 7. exhaust gas temperatures of the two systems at hucr for each one, for wide range of equivalence ratios. operating the engine with very lean mixtures means increasing the air portion in the mixture, result in higher volumetric efficiency. also, due to lower temperature of the combustion chamber that will reduce its temperature and increases the interring mass flow rate for the subsequent cycle. as fig. 8 represents, hcci has higher volumetric efficiency compared with a gasoline engine. the mechanical efficiency of hcci reduced with about 19.86% in relation to the si engine, as fig. 9 represents. brake power reduction due to working on lean mixtures and fp increased due to cr resulting in mechanical efficiency reduction. nahedh mahmood ali al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 102110 (2016) 107 fig. 8. volumetric efficiency of the two systems at hucr for each one, for wide range of equivalence ratio hcci engine produced high brake power with lower brake specific fuel consumption compared with the si engine. as fig. 10 shows, the brake thermal efficiency of hcci exceeded gasoline engine. fig. 9. mechanical efficiency of the two systems at hucr for each one, for wide range of equivalence ratios hcci engine distinguished by near zero nox concentrations, as fig. 11 represents. the engine operation with lean equivalence ratio produced lower temperatures inside the combustion chamber. these temperatures are not enough for n2 and o2 to react effectively. fig. 10, brake thermal efficiency of the two systems at hucr for each one, for wide range of equivalence ratio. fig. 11. nox concentrations of the two systems at hucr for each one, for wide range of equivalence ratio because of air overabundance in lean mixtures operation, the resulted co2 concentrations were limited to the minimum values, as fig. 12 appears. the co2 levels are at the minimal values compared to those produced from the si engine. fig. 13 represents the emitted co concentrations for the two tested engines. partial oxidation of fuel to co can occur at extremely lean mixtures. three temperatures govern the hcci engine. the required auto-ignition temperature to get fuel/air mixture ignited; the combustion temperature must reach at least 1400 k to have good combustion efficiency, in the same time, this temperature must not increase to more than 1900 k to prevent the formation nox. nahedh mahmood ali al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 102110 (2016) 108 fig. 12. co2 concentrations of the two systems at hucr for each one, for wide range of equivalence ratio. fig. 13. co concentrations of the two systems at hucr for each one, for wide range of equivalence ratio. the ubhc concentrations in the recent study seem lower than the si engine levels depending on the optimal gasoline injection timing that provides better air-fuel mixture homogeneity. fig. 15 manifests the engine noise, which increased with increasing equivalence ratio, but hcci produced lower noise with about 26.68% compared to the gasoline engine. the reactivity of the fuel-air charge is too high at rich mixtures, where the burn rate becomes extremely high at these ratios. the pressure rates inside combustion chamber increase resulting in mechanical stresses and noise. unhc concentrations behaved as co and co2 concentrations, and stayed at the minimal values, as fig. 14 represents. it can be observed that ubhc had higher values at ø=0.2, and reduced from its value while moving towards ø=0.7, the combustion temperatures increase with increasing fuel quantity in the mixture, and this increment reduces ubhc concentration although it was little. fig. 14. ubhc concentrations of the two systems at hucr for each one, for wide range of equivalence ratio. fig. 15. noise level of the two systems at hucr for each one, for wide range of equivalence ratio. 4. conclusions hcci engine equivalence ratio is usually very lean and strongly diluted; the average peak temperature is much lower than that of the si mode. the heat losses from hcci engine are reduced, and the formation of nox is avoided to a large extent; nox emissions of hcci engines are often near zero. emissions of co and hc were lower than the si engine emitted emissions. fuel consumption values have the potential to be approximately 28% less than si mode. also, hcci mode produced brake power lower than the si engine with about 6%. the hcci engines have higher brake thermal efficiencies compared to si engines. notation btdc before top dead centre bp brake power bte brake thermal efficiency nahedh mahmood ali al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 102110 (2016) 109 co2 carbon dioxide co carbon monoxide cr compression ratio ca crank angle db decibel di direct injection fp friction power it injection timing n engine speed (rpm) nox nitrogen oxides lcv lower calorific value oit optimum injection timing ost optimum spark timing t engine torque ubhc unburnt hydrocarbon vsn swept volume greek letter ø equivalence ratio acknowledgements the author would like to thank the technical collage, the middle technical university for their support to achieve this research. 5. references [1] martins m, zhao h, performance and emissions of a 4-cylinder gasoline engine with controlled auto-ignition, j. of the braz. soc. of mech. sci. & eng, vol. 36, no. 4, pp. 436-440, 2012. [2] wu z, bao t, zhang q, yan s and deng j, experimental study on spray combustion characteristics of gasoline-diesel blended fuel in a controllable active thermo-atmosphere, fuel, vol. 135, pp. 374-379, 2014. [3] coskun g, soyhan h s, demir u, turkcan a, ozsezen a n and canakci m, influences of second injection variations on combustion and emissions of an hcci-di engine: experiments and cfd modeling, fuel, vol. 136, pp. 287-294, 2014. [4] ghazikhani m, kalateh m r, toroghi y k, and dehnavi m, an experimental study on the effect of premixed and equivalence ratios on co and hc emissions of dual fuel hcci engine, proceedings of world academy of science, engineering and technology, vol. 40, 2009. [5] turkcan a, ozsezen a n, and canakci m, experimental investigation of the effects of different injection parameters on a direct injection hcci engine fueled with alcoholgasoline fuel blends, fuel processing technology, vol. 126, pp. 487-496, 2014. [6] su h, vikhansky a, mosbach s, kraft m, bhave a, kim k, kobayashi t and mauss f, a computational study of an hcci engine with direct injection during gas exchange, combustion and flame, vol. 147, 2006. [7] elkelawy m, yu-sheng z, alm el-din h, and yu j z, challenging and future of homogeneous charge compression ignition engines; an advanced and novel concepts review, journal of power and energy systems, vol. 2, pp. 1108-1119, 2008. [8] zhao f, asmus t w, assanis d n, dec j e, eng j a and najt p m, homogeneous charge compression ignition (hcci) engines: key research and development issues, 1st edition, sae inc., canada, pp. 1–658, 2003. [9] patil s g l, prasad b, maheswar d, strategies of combustion control for hcci engine, international journal of emerging technology and advanced engineering, vol. 3, no. 3, pp. 101-107, 2013. [10] yao m, zheng z, and liu h, progress and recent trends in homogeneous charge compression ignition (hcci) engines, progress in energy and combustion science, vol. 35, pp. 398-437, 2009. [11] ren z and zhu g g, modeling and control of an electric variable valve timing system for si and hcci combustion mode transition, 2011 american control conference on o'farrell street, san francisco, ca, usa, 2011. [12] kung e h, priyadarshi s, nese b c and haworth d c, a cfd investigation of emissions formation in hcci engines, including detailed nox chemistry, 2006 multidimensional engine modeling users’ group meeting, detroit, 2006. [13] walton s m, he x, zigler b t, wooldridge m s, and atreya a, an experimental investigation of iso-octane ignition phenomena, combustion and flame journal, 2006. [14] keating e l, applied combustion, 2nd edition, taylor & francis group, llc, 2007. ��� 4، ا���د����12 ا���ارز � ا������� ا���� �ھ ���د ���� ،110-102 )2016( 110 ��ت أداء و �� �ت ��ر � درا�� � ل '�0 /.�ط�*(�إ �%كو �%ك ا*(��ل '��&%ارة ���ا �3 يذ��) ���* )hcci( �ھ ���د ��� ��� / ��� ھ���� ا���اد�� ا�"!���� ��ا� gmail.comnahidh.mahmood@60: ا�(&)� ا'�!"&و$# �� ا��4 �ط )&ى,-$.��$�� /�)9 وا�8ا ��7&6�ت ا.4"��ل /��2&ارة و/�"�7&6�ت . ا���)� �= ا�(�?<�= أن �8:�� ا'�4�ل ا'$-,�ط# ���72 � @��a إذ �= ا�"�fام ���4 ��ح '�/ ��aا'?"&اق ذا ha2"�@ $�اaاء، و�kا����د وا� =� lmf� l��n o�:f/ ��$��"��ر ھrا ��a �q اp. ا'�4�ل ا.$-,�ط# ���72 )" �زو��= . �atd110 ا�"�fام �7&ك ا4"��ل /��2&ارة �",�& $�v ا.$-,�ط $�ع إذ . ا.�:�ب s# ا.?"&اق s# ھrة ا��را����رب /��"�fام و��د ا��y�a ا�" ).٨٢=ذي ر�� أو6"�$#(ا��&ا�# ا�"q:��ي �7&ك @�8 ��$�!���n �`s��m ^�ا، �^_ ا�^"9kك $^�ahcci 8�(= ا��"�[h إ!� v��/ 7^# أ�^@ /7^�ود)!��7^&ك #28% _^��ر$^� q�. ا4^"��ل /��2^&ارة �ت ا���(�<̂^� �:̂^y /7̂^�ود ^̂a�:̂^� ان ا���ا���: h]��$# أ�6̂^�� ا�!&/̂^�ن، ٧٩.٩١%.ول ا�6̂^�� ا�!&/̂^�ن، % ٨٥.٩٩.6��̂^�� ا���"̂^&و �=، % ٩١.٢٧/��̂^y ا��"̂^^̂>� �7̂^&ك ا.4̂^"��ل /��2̂^&ارة% ٨٣.٥٦و _^̂��ر$̂^� q��7̂^&ك . �:k�̂^�رو6�ر/�$�ت i�̂^& ا�7"&�̂^� =^̂8 h"^̂$hcci ء أ�̂^@ /7̂^�ود�^̂n�n7̂^&ك % ٢٦.٦٨� =^̂� .ا.4"��ل /��2&ارة (microsoft word \321\355\307\326 \332\317\344\307\344 1022) al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 15, no. 1, march, (2019) p.p. 1022 design and simulation of closed loop proportional integral (pi) controlled boost converter and 3-phase inverter for photovoltaic (pv) applications riadh adnan kadhim department of electromechanical engineering/ university of technology email: alazizdl@gmail.com (received 17 april 2018; accepted 14 june 2018) https://doi.org/10.22153/kej.2019.06.001 abstract this research deals with the design and simulation of a solar power system consisting of a kc200gt solar panel, a closed loop boost converter and a three phase inverter by using matlab / simulink. the mathematical equations of the solar panel design are presented. the electrical characteristics of the panel are tested at the values of 1000 w/m� for light radiation and 25 °c for temperature environment. the proportional integral (pi) controller is connected as feedback with the boost converter to obtain a stable output voltage by reducing the oscillations in the voltage to charge a battery connected to the output of the converter. two methods (particle swarm optimization (pso) and zeiglernichols) are used for tuning pi controller to enhance the overall performance of the system. the sine pulse width modulation (spwm) technique was used to obtain a pure 3-phase in low distortion. the voltage and current output values of ± 14v and ± 2.8a are obtained, and the total harmonic distortion (thd) value is 4.20%. keywords: photovoltaic systems, boost converter, pi controller, inverter, pso algorithm, zeiglernichols method. 1. introduction nowadays, photovoltaic (pv) panels are widely used to convert the solar radiation into electricity. the optimum operating point depends on environment conditions such as cell temperature and solar irradiation. k. k. and a. s. kumar [1] presented the modeling of photovoltaic system controlled by maximum power point tracking (mppt) technology. they are focus on the design and simulation of pv system connected to power inverter. matlab/simulink results are obtained for standard operating conditions. m. f. adnan et al [2] presented the design and simulation of a boost converter with proportional integral derivative (pid) controller to enhance the performance of the system. the objective of a boost converter is to achieve a constant output voltage despite variations in source voltage. u. jagadeesh and k, l. achari [3] presented model of a buck-boost converter for photo-voltaic applications. they used perturbation and observation (p&o) method to achieve maximum power point. k.k.saravananet al. [4] presented the use 3-phase inverter to give higher reliability. the proposed current source inverter (csi) removes the earth leakage current, then increasing the efficiency. y. v. dhotre and ponkshe v.s. [5] present open loop and closed loop controlled systems by using matlab software. pid controller is used to reduce the oscillations in output voltage. the system used a boost converter to achieve fast response and reduce the hardware. k.umadevi et al [6] presented the simulation of a pv system using matlab. spwm technique is used to control the operation of inverter, and psim (a simulation tool designed for power electronics and dynamic systems) software is used for converter topology. a. a. bakar et al [7] presented the design of pi controller for a boost converter using real riadh adnan kadhim al-khwarizmi engineering journal, vol. 15, no. 1, p.p. 1022 (2019) 11 time interface (rti) to achieve faster transient response which can be observed by using dspace rti (an open source repository software package). g. mühürcü et al [8] presented the design of buck converter which was added to discrete time pi controller. the efficiency of control process is maintained at high level by optimizing the proportional gain (��) and integral gain (��) in pso algorithm. m. dave and s. r. vyas [9] presented the modeling and simulation of solar inverter by using matlab software. spwm technique is used for the switching operation to reduce the harmonics in the output. a. m.thu and k. s. lwin [10] presented a method to build a pure sine wave inverter system which used operational amplifier, dc-dc converter and power mosfets. the pulse width modulation (pwm) signal is produced by using the tl 084 and lm 339 integrated circuits. s. rout [11] presented the implementation of pv model hardware by using the matlab/simulink software. the p&o algorithm for mppt control is simulated in the matlab/simulink software. the design of converter is also presented. p. aravind and s.m.g. kumar [12] proposed an application of pso to set the pi controller for nonlinear process. the tuning values of the controller are tested in level control system. they prove that pso-pi controller yield good results than gain scheduling method.this paper presents the design and simulation of a pv power system consist of solar panel type kc200gt, dc-dc boost converter for interface between pv panel and 3-phase inverter. the pi controller is used to regulate output voltage of boost converter to get the fast transient response by adjusting the value of proportional gain ( �� ) and integral gain ( �� ) accordingly. the sinusoidal ac output voltage is achieved by inverted boost converter voltage via inverter by using spwm technique which gives a pure sine wave with low thd. 2. system design the block diagram of the proposed system design is shown in fig. 1. kc200gt solar panel is used for pv module. the boost dc-dc converter with pi controller is used to adjust the output voltage. the output of battery is fed to 3phase voltage source inverter. the filter is used to achieve a pure sine wave. fig. 1. the proposed system design. 3. pv cell the main part of pv module is a pv cell. there are different types of pv module depending on the cells compose the module itself. silicon single-diode pv cells is applicable to simulate in this paper. the pv model consists of a photocurrent source, series resistance, nonlinear diode and shunt resistance as shown in fig. 2[13]. fig. 2. pv cell model. the main parameters that characterize a photovoltaic panel are open circuit voltage ( �), short circuit current (� �), maximum power point (����) and efficiency (�)[14].the mathematic equation for the voltage and current can be described as [13]: i � i�� � i� �exp ��� !"#$ % & ' ( � 1* � � !"#$ #$+ * … (1) where: ��, is photocurrent; � is diode saturation current; is electron charge (1.602 × 10-19 c; . is pn junction ideality factor; / is boltzmann’s constant (1.381 × 10-23); 0 is cell temperature. photocurrent ( i�� ) is the function of cell temperature and solar radiation can be described as: i�� � � 1 1234* 5i��.789 : c'�t � t789=> … (2) where: ? is the real solar radiation (w/m2); ?@ab , 0@ab , ��,,@ab are the solar radiation, cell riadh adnan kadhim al-khwarizmi engineering journal, vol. 15, no. 1, p.p. 1022 (2019) 12 absolute temperature, photocurrent respectively in stc; de is the temperature coefficient (a/k). diode saturation current � varies with the cell temperature as: � � � fgh i j e eklmno i gpq rsitu viw i j x eklm � x eny … (3) where: � ,@ab the diode saturation current (a) ; z[ is the band-gap of the cell semiconductor (ev). pv panel is composed of cells tied in parallel and series. the equivalent circuit of pv array can be described as illustrated in fig. 3[13]. fig. 3. pv model. based on the equivalent circuit of a pv module, its characteristic equation is given as follows [15] i � n�i�� � n� i i� i ]exp ^ � %i_i' j `$ : "i#$ `a nb � 1c � `a #$+ j `$ : "i#$ `a n … (4) where: d and d� are series and parallel cell numbers respectively. matlab/simulink is used to implement the mathematical equation (4), as shown in the fig. 4. the parameters used in simulink are listed in table 1[15]. fig. 4. simulink model of pv cell in matlab. table 1, kc200gt parameters values for solar module at 1000 w/m2 w/m2, 25°c. value parameter 1000 w/m� g789 298 k t789 24 n� 8.21 a i�h 32.9 v vjh 7.61 a ik 26.3 v vk 0.0009 a/k kl -0.123 v/k km 1.237 ev eo 0.221 ω r� 415.3 ω r�� 1.35 a 4. boost dc-dc converter the dc-dc boost converter is a switching step up converter. fig.5 shows the electronic circuit of the converter [16]. fig. 5. boost converter circuit. v_i top 25 repeating sequence product p_v top g vpv1 vpv ipv p g 1000 workspace_ipv ipv workspace_vpv vpv workspace_ppv ppv riadh adnan kadhim al-khwarizmi engineering journal, vol. 15, no. 1, p.p. 1022 (2019) 13 there are two modes of operation the boost converter. mode 1 begins at r � 0 and ends at r � r t when the transistor is switched on. the inductor current uv�w= increased linearly and the voltage measured on the inductor is � . when the transistor switched off, mode 2 is begin at r � r t and ends at r � r . the uv�w= decrease until the transistor is turned on to begin the next cycle. in this period, the voltage across the inductor is become � � . in steady state, time integral of the inductor voltage over one time period must be zero as follows [16]: vl tjy : �vl � vj=tj99 � 0 … (5) where, �: the input voltage, : the average output voltage, r t : the switching on time, r � r bb : the switching off time. dividing both sides by 0 and rearranging items yield. z { � '$ |z44 � x x}~ … �6= where 0 ,: the switching period, d : the duty cycle. switch is triggered by the pulse which is generated by pi controller using pwm technique. � is the dc input voltage taken from the pv module. when switch turns on the current of inductor is increases, and the relationship between � and � as following [16]: vl � l �"$ �| … (7) using laplace transformation, vl�s= � l s i��s= … (8) from fig.5. , � can be given as: vj�s= � i��s=r … (9) from equation 8, z��= {��= � # �� … (10) equation (10) is the basic laplace transformation equation of the boost converter. to calculate the capacitor and inductor of the converter, the following basic equations must be used [6], c � "z~ 9∆ z … (11) l � { ~ 9 ∆"� … (12) where: h is switching frequency and � is output current. 5. regulated closed loop circuit the battery in solar system is used to store the power to fill the energy requirements at night or during period of low solar irradiation. battery storage should be controlled to avoid overcharging or frequent deep discharging. switch mode dc dc converters permit the charge current to be decreased continuously to maintain the battery voltage at a defined value. in open loop system, the output from pv panel is the input of boost converter. the converter output is not constant, and it's not appropriate for battery charging. this is the disadvantage of the system [5]. to overcome this problem, closed loop system with pi controller as feedback is used. the output of the pi controller is writing as follows [17]: ���r= � /� �g�r= : x �� � g�r=�pw � � : ��� … (13) where: ���r= is controller output, �� is the controller proportional gain, e(t) is the error signal, �� the integral time constant, ��� is the bias signal of the actuator. the transfer function gc(s) of the pi controller can be writing as follows: ?���= � /� �1 : x �� � … (14) in the present mode, the pi controller presents the advantage of eliminating the deviation between the output and the set point. the error signal is generated by comparing ( @ab ) with the battery output voltage. this error signal is fed to pi controller which generates the control signal for changing the time period for turn on and off to achieve the constant output voltage ( ). fig. (6) shows the block diagram of closed loop boost converter. the principle of that is when a load change, a new controller output is produced, and the error is produced also. this operation is repeated continuously and the controller output is provided through a sum of proportional plus integral action until the error became zero. riadh adnan kadhim al-khwarizmi engineering journal, vol. 15, no. 1, p.p. 1022 (2019) 14 fig. 6. block diagram of closed loop boost converter. 6. simulink of closed loop system fig.7 show the simulink circuit of pv panel connected to boost converter with pi controller and battery to maintain constant output voltage. simulation studies is carried out by using following data: l=2.2mh, c= 600 µf. fig.7. closed loop simulink model. 7. particle swarm optimization(pso) pso algorithm is initialized with a number of random particles with random distribution that is assigned to random velocity. the particles are a swarm moving in the search space looking for optima by updating the particles positions during the generations. each particle moves in the search space with an adaptive velocity and adjusts its trajectory towards its best solution (fitness) [18]. the fitness function is used to determine the best fitting solution is achieved by evaluates the performance of particles. all possible sets of controller parameter values are adjusted so as to minimize the error criterion. the index parameters most often used are [19]: integral of the absolute error (�.z= � � |g�r=|� � �r … (15) integral of the square error ���z= � � g�� � �r=�r … (16) integral of the time -weighted absolute error ��0.z= � � r|g�r=|� � �r … (17) mean square error ���z= � � r g�� � �r=�r …(18) where g�r= is the deviation (error) of the response from the desired set point. 8. ziegler-nichols method in this method, the ultimate gain of a proportional controller and the ultimate period of oscillation are used to represent the dynamic powergui discrete, ts = 5e-006 vpv voltage 1 v + vo v.ref 28 vmeasurement v + t 25 scope6 repeating sequence repeating relational operator >= pules p_v top g vpv 1 ipv pi controller pi mosfet3 g m d s mosfet2 g m d s l ipv s + g 1000 diode c4 c3 battery + _ m add workspace_vpv vpv workspace_vo vo workspace_pules pules <soc (%)> <current (a)> <voltage (v)> battery boost converter pi controller riadh adnan kadhim al-khwarizmi engineering journal, vol. 15, no. 1, p.p. 1022 (2019) 15 characteristic of the process. the following procedure is used to determine the ultimate gain and period: the steps for tuning a pid controller as follows:[20]: 1. reduce the integrator and differentiator gains to 0. 2. increase kp from 0 to some critical value kcr= kp at which sustained oscillations occur. 3. record the value kcr and the corresponding period of sustained oscillation, pcr 4. the controller gains are now specified as follows: table 2, ziegler nichols method �� �� �� pid type 0 ∞ 0.5��@ p 0 ��@1.2 0.45��@ pi ��@8 ��@2 0.6��@ pid 9. power part 9.1 inverter circuit the main component of the power part is the six power mosfets, six freewheeling diodes, one with each mosfet is used for the bypass of back e.m.f. the schematic diagram of the power part is shown in fig.8[21]. when the generated power is transmitted to the load, it is necessary to use the inverters with three phase output. fig. 8. schematic of power part of inverter. 9.2 sinusoidal pulse width modulation (spwm) spwm technique is used to generate ac current with low harmonic distortion. the multiple numbers of different widths pulses are generated with this modulation technique. six switching pulses is generated from discrete pwm generator. these pulses are used for switching the mosfet transistors in the power stage. the reference signal frequency is used to determine the inverter output, and the speed of switching the inverter to determine on and off time period. switching frequency affects the output of the inverter that results the harmonics on the output [2]. spwm technique is depending on comparing a high-frequency carrier with a low-frequency sinusoidal signal. the carrier has a constant period, this leads to constant switching frequency. the instant of switching is determined from the crossing of the modulating signal and carrier. 9.3 lc filter the design of an electric system requirement the reduction of the harmonic, therefore, a filter connected to output is used for this purpose. this filter topology is relatively easier to design and it has substantially sophisticated damping behavior (the value of inductance affected on cut-off frequency, but the value of capacitance affected on the output voltage quality) [21]. 10. total harmonic distortion (thd) the harmonic content of a waveform is measured by thd index which is applied to either current or voltage. thd is the summation of all the harmonic frequency currents to the fundamental [22]. the thd can be calculated by the following equation. thd � £∑ ¥¦§+̈©§ ª … (19) where: n is the maximum harmonic order, h is the harmonic order, and vh is h amplitude. 11. simulink of system design the basic components of the simulink model for the system are the pv cell represented by pv3, the dc-dc converter, inverter and lc filters show in fig.9. the dc-dc converter model consists of two static switch, two inductors (l1, l2), diode d, and capacitors (c3, c4). in dcac inverter there are four mosfet transistors switches. lc filter is connected with the load to maintain a constant output voltage decrease output ripple riadh adnan kadhim al-khwarizmi engineering journal, vol. 15, no. 1, p.p. 1022 (2019) 16 fig. 9. simulink model for the system design. 12. results and discussion matlab/simulink software are used for tested the system. the simulation results of electric characteristics of the pv module at temperature of 25°c and irradiation of 1000 w/m2 are shown in fig.10. the component values used in simulation are « =0.221ω , « ,= 415.3ω . the results are � 8.2 , �� � 250¬ . (a) (b) fig. 10. electric characteristics of pv module. a pv panel is connected to the step up converter to increase the voltage from 20 v to 28v which is necessary to supply the inverter to generate the required ac output voltage. the pv voltage and current are shown in fig. 11. the voltage ( �­) equal to 20 v and it is remain stable after 0.2sec as shown in fig 11a. the current is equal to 8.2a as shown in fig. 11b. (a) (b) fig. 11. vpv and ipv for pv panel. powergui discrete, ts = 5e-006 vpv voltage 4 v + voltage 1 v + vo2-io2 vo v.ref 28 vmeasurement v + three-phase v-i measurement vabc iabc a b c a b c three-phase series rlc load a b c t 25 scope6 spwm repeating sequence repeating relational operator >= pules p_v top g vpv1 ipv pwm pi controller pi mosfet3 g m d s mosfet2 g m d s load a b c a b c l filter1 a b c a b c l ipv s + g 1000 discrete pwm generator pulses diode c4 c3 c filter 1 a b c a b c battery + _ m add 6 g c e 5 g c e 4 g c e 3 g c e 2 g c e 1 g c e workspace_vpv vpv workspace_vo2 vo2 workspace_vo vo workspace_spwm spwm workspace_pules pules workspace_io2 io2 <soc (%)> <current (a)> <voltage (v)> 0 5 10 15 20 25 30 35 0 1 2 3 4 5 6 7 8 9 10 volltage (v) c u rr e n t( a ) i-v characteristic at t=25 c and g=1000 w/m2 0 5 10 15 20 25 30 35 0 50 100 150 200 250 voltage (v) p o w e r( w ) p-v characteristic at t=25 c and g=1000 w/m2 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 0 5 10 15 20 25 time(sec) v o lta g e ( v ) vpv (voltage) 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 1 2 3 4 5 6 7 8 9 time(sec) c u rr e n t (a ) ipv(current) riadh adnan kadhim al-khwarizmi engineering journal, vol. 15, no. 1, p.p. 1022 (2019) 17 there is some distortion from 0.0 sec to 0.2 sec, this distortion can be reduced by connect the pv panel to dc-dc boost converter which is controlled by pi controller. analysis of boost converter is performed in continuous mode of operation with switching 1 khz. switching pulse generated from pi controller is used to control the operation of boost converter which is the output voltage is 28v as shown in fig. 12.this output voltage is obtained at the ��= 0.001125 and ��= 0.092270. fig. 12. converter output. the parameters used in pso algorithm is listed in table (3). dynamic performance analysis of boost converter with different types of controller is shown in table (4). it is clear that the advantage of pso-pi algorithm is reducing of settling time, peak time and the steady state error when compared with other three methods (ziegler-nichols-pi(zn-pi), genetic algorithm fractional order pi (ga-fopi), queen bee assist genetic algorithm(qbga)-fopi. table 3, pso parameters parameters values population size 49 numbers of iterations 50 inertia weight(w) 0.9 cognitive coefficient(dx) 0.9 social coefficient(d�) 0.12 table 4, dynamic performance analysis of boost converter previous works(reference 23) present works specification qbga-fopi ga-fopi zn-pi pso-pi 0.065 0.218 0.85 0.3441 rise time(s) 0.1098 0.3755 0 0 peak time(s) 2.9883 0.3755 0.95 0.7028 setting time(s) 0.3685 0.2824 0.00765 0.001125 �� 34.0936 10.2315 0.04172 0.092270 �� 0.15 -0.43 0.2158 0.102 ��z the typical discharge characteristics of nickel cadmium battery can be separated into three areas as shown in fig.13. the first area is the area above the nominal value that represents the overshoot of battery voltage. the voltage is slightly changed in the nominal area which represents the second area. when the nominal capacity of battery power is discharged, it is followed by the third area of operation in which the battery voltage decreases very fast. fig. 13. battery charging current. 0 0.05 0.1 0.15 0.2 0.25 0 5 10 15 20 25 30 time (sec) v o lta g e (v ) vo (converter) 0 1 2 3 4 5 6 7 20 25 30 nominal current discharge characteristic at 0.2c (1.4a) time (hours) v o lt a g e 0 1 2 3 4 5 6 7 20 25 30 e0 = 25.695, r = 0.085714, k = 0.37501, a = 2.88, b = 2.1429 time (hours) v o lt a g e discharge curve nominal area exponential area riadh adnan kadhim al-khwarizmi engineering journal, vol. 15, no. 1, p.p. 1022 (2019) 18 fig.14 shows the switching signals (s1, s2, s3, s4, s5, and s6) used to drive the mosfet transistors to regulate the inverter output voltage. it is spwm signals. the characteristic of spwm generator used in the simulink design as follows: modulation index= 0.8; carrier frequency=1080; f=50hz; phase difference=120. the non-sinusoidal output signal which comes from the inverter is connected after the dc converter. the dc output voltage from the inverter is converted to ac. the value of the output voltage is 28v in square wave. this is illustrated in fig.15. fig. 14. switching signals. fig. 15. outputs from inverter voltage before filters. the voltage and current injected into load. the sinusoidal output which comes from the inverter is connected with the filter. the elimination of the harmonic components from the output for the supply to the local load is achieved by the capacitor in the filter circuits as illustrated in fig.16. as it can be seen, the voltage and current are in phase which means the whole system operates at unity power factor with no reactive power exchange. fig.17 shows the thd curve. the percentage value of thd is 4.20%. 0 0.2 0.4 0.6 0.8 1 -2 -1 0 1 2 s1 time(sec) 0 0.2 0.4 0.6 0.8 1 -2 -1 0 1 2 s3 time(sec) 0 0.2 0.4 0.6 0.8 1 -2 -1 0 1 2 s5 time(sec) 0 0.2 0.4 0.6 0.8 1 -2 -1 0 1 2 s2 time(sec) 0 0.2 0.4 0.6 0.8 1 -2 -1 0 1 2 s4 time(sec) 0 0.2 0.4 0.6 0.8 1 -2 -1 0 1 2 s6 time(sec) 0 0.2 0.4 0.6 -30 -20 -10 0 10 20 30 spwm time(sec) v o lta g e (v ) riadh adnan kadhim al-khwarizmi engineering journal, vol. 15, no. 1, p.p. 1022 (2019) 19 (a): load voltage (b): load current fig. 16 (a) load voltage, (b) load current. fig. 17. thd window. 13. conclusion a complete matlab/simulink of pv module and closed loop boost converter connected to 3phase inverter are carried. the electrical characteristics (p-v and i-v curves) are achieved for kc200gt solar module. the output voltage of pv module is equal to 8.2 , and the maximum power �� is equal to 250w. the oscillation in output voltage is reduced by connect a pi controller as a feedback in dc-dc converter. the boost converter increases the voltage from 20v to 28v. particle swarm optimization (pso) and zeigler nichols method are used for tuning pi controller. the response of pso gives a better performance as compared to ziegler and nichols methods which helps to overcome the problem of overshoot & settling time. spwm technique is used with inverter to generate sinusoidal voltage and current with low harmonic distortion. the output voltage and current obtained are ±14v and ±2.8a respectively, and their signals are in phase with percentage value of thd is 4.20%. 14. references [1] k. kirubasankar, a. senthil kumar, "inverter power stage connected with pv-grid", circuits and systems, vol.7 issue 13, pp. 4113-4123, 2016. 0 0.1 0.2 0.3 0.4 0.5 -20 -15 -10 -5 0 5 10 15 20 time(sec) v o lta g e (v ) vo 3-phase ( inverter) 0 0.1 0.2 0.3 0.4 0.5 -4 -3 -2 -1 0 1 2 3 4 time(sec) c u rr e n t( a ) io 3-phase(inverter) 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 -10 0 10 selected signal: 100 cycles. fft window (in red): 4 cycles time (s) 0 10 20 30 40 50 60 70 80 90 100 0 2 4 6 8 frequency (hz) fundamental (50hz) = 13.37 , thd= 4.20% m a g ( % o f f u n d a m e n ta l) riadh adnan kadhim al-khwarizmi engineering journal, vol. 15, no. 1, p.p. 1022 (2019) 20 [2] mirza fuad adnan, mohammad abdul moin oninda, mirza muntasir nishat, nafiul islam," design and simulation of a dc dc boost converter with pid controller for enhanced performance", international journal of engineering research & technology (ijert), vol. 6, issue 09, pp. 2732, 2017. [3] u. ajagadeesh, k. lokesh achari,"a buckboost based dc/ac converter for residential pv application by using mppt ", international journal of advanced computational engineering and networking, vol. 2, issue 11, pp. 87-90, 2014. [4] k. k.saravanan, n. stalin, t. sree renga raja, " design and investigation of grid connected current source inverter for photovoltaic system", international journal of advanced engineering technology, vol. 7, issue 2, pp. 280-284, 2016. [5] yogini v dhotre, ponkshe v.s., "simulation of closed loop controlled boost converter for pv system" international journal on recent and innovation trends in computing and communication, vol. 2, issue 6, pp.1412-1416, 2014. [6] k.umadevi, p.nalandha madevi, c. chenn kesavan, "modelling of photovoltaic system with converter topology for grid fed operations", international journal of engineering and technology (ijet), vol. 6 issye 5 , pp. 2392-2400, 2014. [7] a. a. bakar, w. m. utomo, t. taufik, s. aizam and jumadril", dc/dc boost converter with pi controller using real-time interface", arpn journal of engineering and applied sciences, vol. 10, issue 19, pp. 9087-9082, 2015. [8] gülçin mühürcü, ercan kose, aydin muhurcu, ali kuyumcu," parameter optimization of pi controller by pso for optimal controlling of a buck converter's output", ieee, doi: 10.1109/idap.2017.8090234, 2017 [9] maulik dave, sanjay r. vyas," simulation and modeling of single phase dc-dc converter of solar inverter", international research journal of engineering and technology (irjet), vol. 02, issue 09, dec.pp.2225-2230, 2015. [10] aye myat thu, kyaw soe lwin," design and implementation of solar inverter for pure sine wave inverter", international journal of scientific engineering and technology research, vol.03, issue 08, pp. 1293-1297, may. 2014. [11] smitanjali rout," mathematical modelling of grid connected photovoltaic system using matlab/simulink and hardware implementation", international journal of computer applications (0975 – 8887), international conference on emergent trends in computing and communication (etcc 2015). [12] p.aravind, s.m.girirajkumar," optimal tuning of pi controller using swarm intelligence for a nonlinear process", international journal of advanced research in electrical,electronics and instrumentation engineering, vol. 2, issue 12,pp 5949-5958, 2013 [13] e. benkhelil and a. gherbi, "modeling and simulation of grid-connected photovoltaic generation system", revue des energies renouvelables sienr’12 ghardaïa, pp. 295 – 306, 2012. [14] qais mohammed aish, "temperature effect on photovoltaic modules power drop", alkhwarizmi engineering journal, vol.11, no.2, pp.62-73, 2015. [15] dominique bonkoungou, zacharie koalaga, donatien njomo and françois zougmore," an improved numerical approach for photovoltaic module parameters acquisition based on single-diode model" international journal of current engineering and technology, vol.5, no.6, pp.37353742, 2015 [16] mitulkumar r. dave and k.c. dave," analysis of boost converter using pi control algorithms", international journal of engineering trends and technology, vol.3, issue 2, pp.71-73, 2012. [17] j.-p. corriou, "process control", springer international publishing ag 2018. [18] ercan kose*1, aydin muhurcu2," the control of a non-linear chaotic system using genetic and particle swarm based on optimization algorithms", international journal of intelligent systems and applications in engineering, vol.4, issue 4, pp. 145-149, 2016 [19] k. mohamed hussain, r. allwyn rajendran zepherin, m. shantha kumar," comparison of tuning methods of pid controllers for foptd system", international journal of innovative research in electrical, electronics, instrumentation and control engineering,vol. 2, issue 3, pp. 1177-1180, 2014. [20] susmita das, ayan chakraborty, jayanta kumar ray, soumyendu bhattacharjee, biswarup neogi, " study on different riadh adnan kadhim al-khwarizmi engineering journal, vol. 15, no. 1, p.p. 1022 (2019) 21 tuning approach with incorporation of simulation aspect for z-n (zieglernichols) rules" international journal of scientific and research publications, volume 2, issue 8, pp. 1-5, 2012. [21] sohaib tahir, jiewang, mazhar hussain baloch, ghulam sarwar kaloi," digital control techniques based on voltage source inverters in renewable energy applications: a review electronics", 7, 18, 2018. [22] shravani mathur, vikas kumar," calculation of total current harmonic distortion by pwm method for permanent magnet synchronous motors" international journal of engineering research and applications (ijera), vol. 3, issue 3, pp.493-496, 2013. [23] r. senthilkumar, v. manikandan," design of fractional order pi controller using metaheuristic algorithms applied to dc-dc boost convertera comparison", arpn journal of engineering and applied sciences, vol. 10, no. 11, pp. 4832-4837, 2015. )2019( 1022، صفحة 1د، العد15دجلة الخوارزمي الهندسية المجلم رياض عدنان كاظم 22 وعاكس ثالثي الطور piطة سادائرة مغلقة مسيطر عليه بو يذ boostومحاكاة محول تصميم للتطبيقات الضوئية رياض عدنان كاظم الجامعة التكنولوجية /قسم الهندسة الكهروميكانيكية alazizdl@gmail.com :البريد االلكتروني الخالصة دائرة مغلقة وعاكس ثالثي يذ boost، محول kc200gtمكونة من لوح شمسي نوع ومحاكاتها يتطرق البحث الى تصميم منظومة قدرة شمسية تم اختبار الخصائص الكهربائية .. تم التطرق الى المعادالت الرياضية الخاصة بتصميم اللوح الشمسي matlab/simulinkالطور باستخدام برنامج دائرة تغذية عكسية للحصول بوصفه مع المحول piدرجة مئوية لدرجة حرارة المحيط . يربط المسيطر 25لالشعاع الضوئي و 1000وح عند القيم لل particle swarmن (يعلى فولتية خرج مستقرة عن طريق تقليل التذبذبات في الفولتية لشحن بطارية تربط على خرج المحول . تم استخدام طريقت optimization و ( zeigler-nichols سيطر لضبط مpi لغرض تحسين االداء الكلي للمنظومة. تم استخدام تقنيةspwm للحصول على موجة . %4.20هي thd، و قيمة ال 2.8a±و 14±تم الحصول على قيم فولتية وتيار خرج المنظومة هي ونقية ثالثية الطورباقل تشويه ، <4d6963726f736f667420576f7264202d20c7d3ede120e6dadeede120e6e3e5e4cf39392d20313037> al-khwarizmi engineering journal al-khwarizmi engineering journal,vol. 13, no. 1, p.p. 99107 (2017) study the effect of multilayer single point incremental forming on residual stresses for bottom plates aseel hamad abed* aqeel sabree bedan** mohanad faeq noori*** *,**,***department of production engineering and metallurgy / university of technology ***email: mohuned_2007@yahoo.com (received 24 october 2016; accepted 22 february 2017) https://doi.org/10.22153/kej.2017.02.004 abstract knowing the amount of residual stresses and find technological solutions to minimize and control them during the production operation are an important task because great levels of deformation which occurs in single point incremental forming (spif), this induce highly non-uniform residual stresses. in this papera propose of a method for multilayer single point incremental forming with change in thickness of the top plate (0.5, 0.7, 0.9) mm and lubrication or material between two plates(polymer, grease, grease with graphite, mos2) to knowing an effect of this method and parameters on residual stresses for the bottom plates. also compare these results for the bottom plates with the single plate at same thickness 0.9 mm.the results showed that when increase thickness of the top plate the value of residual stresses will decrease for bottom plates and when used graphite with grease between two plates gives less residual stresses (r.s = 60.173 mpa.) reverse when used mos2 which will gives a larger residual stresses (r.s = 146.617 mpa.) in the bottom plate. keywords: multilayer single point incremental forming (spif), residual stresses, lubrication. 1. introduction incremental forming is a flexible sheet metal forming operation that uses simple generic and in inexpensive made tools to locally deform a sheet of metal along a predefined tool path without counting on dies. the operation is conducted at room temperature and requires a cnc machining center, a round tip tool and a simple support to fix the sheet being formed [1]. in spif there is only support for work-piece between the two ends but no support for the tool. the blank sheet is clamped in a universal stationary blank holder and the forming tool describes the contour of the desired geometry controlled by a regular cnc machine figure (1) [2]. by depending on how to interact external loads with residual stresses, they can influence the mechanical behavior and the lifetime of components in a negative or positive way. for example, surface tensile residual stresses are harmful to fatigue resistance and even in the not found of an applied stress the existence of a corrosive environment may reason stress corrosion cracking but compressive residual stresses will advance the fatigue resistance level since the residual stresses and applied stresses are additive [2]. fig. 1. schematic of single point incremental forming process [2]. aseel hamad abed al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 99107(2017) 100 setup of multilayer spif multilayer single point incremental forming is the idea of using two plates at the same time, as shown in figure (2). in traditional spif the surface will be affected by the high degree of relative movement between plate and forming tool. using a multi-plate, all this sliding is only affecting on the top plate. the relative movement between the top and bottom plate is very small. the forming process in two plates at the same time will increase process forces. in most cases it will be desirable to keep the thickness of the upper sheet at a minimum. friction between the sheets will among other factors determine how much the plates act like one plate or like two separate plates on top on each other. fig. 2. spif using two plates [3]. 2. experimental work in this paper, the spif was carried out without die and by using 3-axis perpendicular cnc machine. and by using matlab software the cad model of the final shape is created (illustrated in figure (3)). the following steps present the experimental work in this paper which includes: • by using matlab software generating the cad model. • generating toolpath using matlab software. • forming using vertical cnc milling machine. • residual stress test. • we proposed and used aisoplaner tool path for axisymetrical parts. figure (4) illustrated the final part that product in this paper. fig. 3. by using matlab software created the cad model of the final product. fig. 4. the final product is created using single point incremental forming. 3. sheet material in all experiments carried out, sheet metals of an aluminum aa1050 alloy are used. the initial dimension of the sheet is 225�225mm, while the working area with diameter 120 mm according to the blank holder size as shown in figure (5). fig. 5. size of aluminum blank used in this work. aseel hamad abed al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 99107(2017) 101 the first step must be defined the mechanical properties and chemical for each one and after that select the geometric condition many kinds of test is as follow: a. chemical composition the chemical composition of the sheet material is listed in table (1). table 1, chemical composition of the aluminum aa 1050 sheet. b. tensile test figure (6) present tensile test. because the strength in this way is minimum according to literature, therefore these tests result in (90o to rolling direction). but due to an axisymmetric product the most of the experimental work down in isotropic condition .these results are as shown in tables (2). fig. 6. tensile test device with a specimen (a) before test (b) after test. table 2, mechanical properties of aluminum 1050 4. preparation of the specimens for residual stresses testing in order to conduct residual stresses testing the dimensional of specimens must be specific because the dimensions of specimens which the device of residual stresses can test it has a limited dimension, figure (7) explanation how works the specimens for residual stresses testing. fig. 7. preparation of the specimens for residual stresses test. iso. measured element 0-99.5 99.4 al 0-0.05 0.026 mg 0-0.05 0.003 ti 0-0.07 0.0406 zn 0-0.05 0.038 mn 0-0.4 0.31 fe 0-0.05 0.041 cu 0-0.25 0.142 si iso. measured element 105145 109 tensile strength mpa. 70-75 70 modulus elasticity gpa. ≥ 85 95 yield strength (min)mpa. 20-30 28 vickers hardness vpn 2-6 4 elongation 0.33 0.33 poisson ratio aseel hamad abed al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 99107(2017) 102 5. change parameters used in this work 5.1 thickness of top plate change in thickness of top plate at (0.5, 0.7, and 0.9) in order to know effect of change it on residual stresses of bottom plate. the figure (8) shown two plates after incremental forming. fig. 8.two plates after incremental forming. 5.2 lubrication or material between two plates polymer, mos2, grease and graphite with grease are successful lubrication or material which used between two plates in order to know effect these lubrication or material on residual stresses for bottom plates, figure (9) shown successful lubrication or material that used in this work. fig. 9. some successful lubrication or material that used in this work. 6. lubrication used on top plates during spif process, the tool was rotated at spindle speed and the tool head pressed on sheet metal that cause local plastic deformation. the head of tool was subjected to friction and wear of tool also heat is generated when the tool rotate and move along the tool path. this has an effect on the surface quality. in order to decrease these effects between the forming tool and the sheet, many studies have been made to select a suitable lubricant, better type of lubrication that used for spif is an oil sae 30. in this work used pennzoil sae 30 used manually as lubricant throughout the experiments as shown in figure (10). this oil has density of (0.88 g/mm3) at 15.6°c and viscosity index of 105 [4]. the lubrication is utilized so that the cavity of the forming part is filled with oil at all the time during forming. consequently, beside lubrication, the oil provides the forming process as cooling fluid. fig. 10. lubrication on top plates during spif. 7. residual stresses test the forming surface was measured at four different angles using a orionrks 6000 test (the x-ray diffraction technology was used to detect the residual stress) measuring instrument with the angles (0o, 15o, 30o and 45o) and the average residual stress value is recorded in (mpa.) that illustrated in figure (5), the residual stress in original blanks is (-6.29mpa.). this specialized type of stress analysis system using the sideinclination method include stress analysis software, the stress analysis sample stand and xray tube. x-ray stress analysis is very used to aseel hamad abed al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 99107(2017) 103 measurement the level of stress in the material. in the x-ray diffractometry of stress so few changes in the lattice space are measured from the x-ray diffraction pattern profile. the accuracy measurement of the residual stress let the use of the special stress analysis stands connected with the side inclination method. free of absorption error is use in this technique. the software includes following functions, as measurement, peak position calculation, width at half height and stress calculation depending on the type of reflective plane and sample, either the co tube or cr x-ray tube is necessary. the acting single stress measure in four ways in the surface ��. shows an isotropic solid that the strain along an inclined line according to elasticity theory (m3 in figure 5) is: [6] �∅� � 1 � �� ����� ������������� � � �� ��� … �1� use the strains to evaluate the stresses when take the strains in terms of inter-planar spacing and then it can be shown that �∅ � � �1 ������� ��� � �� �� � … �2� this equation allows us to determine from two measurements made in the direction of the stress to be find and a plane normal to the surface. the best method to finding residual stress is the (�����) method. at different psi tilts, a number of xrd measurements are made [7]. the 2-theta peak position or inter-planar spacing is tested and plotted that illustrated in figures (11&12). this equation allows us to determine from two measurements made in the direction of the stress to be find and a plane normal to the surface. the best method to finding residual stress is the (�����) method. at different psi tilts, a number of xrd measurements are made [7]. the 2-theta peak position or inter-planar spacing is tested and plotted that illustrated in figures (11&12). fig. 11. set up for residual stress measurement and residual stress analysis result screen [6]. fig. 12. spectrometer and specimen holder in xrd6000. �∅� strain measured in the ϕψ direction v poisson’s ratio e elastic modulus gpa � , �� principal stresses mpa ϕ angle between the direction the sample and the projection in normal of the diffracting plane deg. ψ angle between the normal of the diffracting plane and the normal of the sample. deg. �� inter-planar spacing at angle ψ å �� inter-planar spacing of normal surface å aseel hamad abed al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 99107(2017) 104 8. results and discussion in order to compare the effect forming processes on residual stresses between single plate (0.9) mm and bottom plates (0.9) mm with change in thickness and insert material or lubrication between two plates, but thickness of bottom plates is constant for all experiments (0.9) mm, the results have been divided into three groups and study effect changes in thickness of top plate and material or lubrication between two plates on residual stresses for bottom plates, these groups are as follows: 1. the first group includes the bottom plates for experiments (4,7,10, 13,16) in which different in material or lubrication were used polymer, grease, mos2, grease with graphite and without anything between two plates with same thickness of top plate (0.5) mm for all experiments in order to know its effect on residual stresses for bottom plates. fig. (13) shows residual stresses for bottom plates are larger than those of a single plate and graphite with grease have less residual stresses and mos2 has the largest residual stresses. 2. the second group involves the bottom plates for experiments (5,8,11,14,17) which have the same parameters and levels of the first group, but they differ in thickness of top plate (0.7) mm for all experiment. fig. (14) shows that the residual stresses for bottom plates are larger than those for a single except when using graphite with grease which have less residual stresses than single plate and all other experiments while grease has the largest residual stresses. 3. the third group includes the bottom plates for experiments (6,9,12,15,18) which have the same parameters and levels to the first group, but differ in thickness of top plate (0.9) mm for all experiments. fig. (15) shows residual stresses for bottom plates are less than for single plate except when using mos2 or grease which have larger residual stresses than single plate and all other experiments. on applying the previous schemes to the influence change in material or lubrication between two plates, the thickness of top plate is constant for each diagram and thickness of bottom plates is 0.9 mm for all experiments. figure (16) shows the effect of change in thickness of top plate on residual stresses for bottom plates and concludes that residual stresses decreased when thickness of top plate increased. table 3, results of residual stresses measurements. exp. no. lub. or material between plates position of plate thickness of plate residual stresses measurement 1 single 0.5 59.342 2 single 0.7 68.23 3 single 0.9 90.526 4 without bottom 0.9 117.754 5 without bottom 0.9 90.443 6 without bottom 0.9 70.769 7 polymer bottom 0.9 120.345 8 polymer bottom 0.9 93.435 9 polymer bottom 0.9 72.355 10 grease bottom 0.9 144.461 11 grease bottom 0.9 127.341 12 grease bottom 0.9 102.038 13 mos2 bottom 0.9 146.617 14 mos2 bottom 0.9 125.663 15 mos2 bottom 0.9 109.925 16 graphite + grease bottom 0.9 111.811 17 graphite + grease bottom 0.9 84.539 18 graphite + grease bottom 0.9 60.173 aseel hamad abed al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 99107(2017) 105 fig. 13. illustration the effect change in material or lubrication between two plates on residual stresses for bottom plates at 0.5 mm thickness of top plate and compared with a single plate. fig. 14. illustration the effect change in material or lubrication between two plates on residual stresses for bottom plates at 0.7 mm thickness of top plate and compared with a single plate. fig. 15. illustration the effect change in material or lubrication between two plates on residual stresses for bottom plates at 0.9 mm thickness of top plate and compared with a single plate. aseel hamad abed al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 99107(2017) 106 fig. 16. illustration the effects of change in thickness of top plates (0.5, 0.7, 0.9) on residual stresses for bottom plates. 9. conclusions 1. the maximum and minimum residual stresses, which is achieved from all experiments at bottom plate is (r.s = 146.617 & r.s = 60.173 mpa.) respectively. 2. the change in thickness of top plate has a greatest effect on residual stresses for bottom plates than change in material or lubrication between two plates. 3. at increased thickness of top plate the residual stresses for bottom plate will be decrease. 4. mos2 lubrication between two plates has greatest value of residual stresses on bottom plate. 5. grease with graphite lubrication between two plates has lowest value of residual stresses on bottom plate. 10. references [1] varithinr.r, gandhinathan.r , pandivelan.c, jeevanavtham .k " modling and optimaization of process parameters of single point incrmental forming of aluminum 5052 alloy sheet using genetic alogrithm-back propagation neural network" international journal of mechanical and production engineering. vol. 2, (2014). [2] v. naga chaitanya, sunder singhsivam s.p, dr. m. gopal, dr. g. murali, "an experimental investigation on the single point incremental forming of aluminium alloy" international journal of engineering research. vol. 3, pp. 155-159, (2014). [3] m. skjoedt, n. bay, b. endelt& g. ingarao " single point incremental forming using a dummy plate multiplate forming", 2nd international conference on new forming technology, bremen, (2007). [4] www.engineeringtoolbox.comcrina [5] x-ray diffraction residual stress measurement, proto manufacturing ltd, (2011). [6] m.e. fitzpatrick, a.t. fry, p. holdway, f.a. kandil, j. shackleton and l. suominen, ''determination of residual stresses by x-ray diffraction issue 2'', manchester materials science centre, (2005). [7] a. pyzalla ,''methods and feasibility of residual stress analysis by high-energy synchrotron radiation in transmissiongeometry using a white beam'', journal of nondestructive evaluation, vol. 19, no. 1, (2000). 2017)( 99-107، صفحة 3د، العد13دجلة الخوارزمي الهندسية المجلم اسيل عبد حمد 107 االجهادات المتبقية في الطبقة المتعددة على للصفائح ييدالتزالنقطيالتشكيل اتأثير دراسة السفلية مهند فائق نوري*** عقيل صبري بدن** اسيل حمد عبد* *,**,*** قسم هندسة االنتاج والمعادن / الجامعة التكنولوجية mohuned_2007@yahoo.comالبريد االلكتروني:*** لخالصةا وهذا بدوره يحدث اجهادات متبقية غير منتظمة بشكل كبير. لذلك ,معرفة مقدار حدوث التشوهات،من التزايدي النقطي مستوى عالٍ في عملية التشكيل . فaي هaذه البحaث تaم اقتaراح طريقaة جديaدة للتشaكيل مهمaةاالجهادات المتبقية وايجاد حلول تكنولوجية للسيطرة والتقليل منها خaالل عمليaة االنتaاج هaي مهمaة والمادة او المزيت بين الصaفيحتين ) ملم٠٫٩, ٠٫٧, ٠٫٥سمك الصفيحة العلوية (والتغيير في هذه الطريقة تأثيرالمتعددة ومعرفة للصفائح التزايدي النقطي ) 2(polymer, grease, grease with graphite, mos ك الطبقة السفلية و مع تثبيت العوامل االخرى كسم لصفيحة السفليةعلى االجهادات المتبقية في ا ذات سaمك يسaاوي سaمك واحaدة صaفيحة باسaتخدامعمليaة التشaكيل مع قطر االداة وحجم الخطوة . وكذلك مقارنة النتائج والسرعة الدورانية معدل التغذية و مaع graphiteيقل مقدار االجهادات بالنسبة للصفيحة السفلية وان استخدام وأظهرت النتائج انه كلما زاد سمك الصفيحة العلوية .ملم ٠٫٩ السفلية ةالصفيح grease ةaادات متبقيaل اجهaي اقaبين الصفيحتين يعط) mpa.(r.s = 60.173 تخدامa2وان اسmos ةaادات متبقيaى اجهaي اعلaيعط(r.s = 146.617 mpa.) .في الصفيحة السفلية <4d6963726f736f667420576f7264202d20c7cde3cf20e6ddd1c7d320e6e4e6d132372d203337> al-khwarizmi engineering journal al-khwarizmi engineering journal,vol. 13, no. 3, p.p. 2737 (2017) robot arm path planning using modified particle swarm optimization based on d* algorithm ahmed t. sadiq* firas a. raheem ** noor alhuda f. abbas *** *,***department of computer science/ university of technology **department of control and system engineering/ university of technology email: drahmed_tark@yahoo.com email: dr.firas7010@yahoo.com email: nooralhudafabbas92@yahoo.com (received 6 september 2016; accepted 7 february 2017) https://doi.org/10.22153/kej.2017.02.001 abstract much attention has been paid for the use of robot arm in various applications. therefore, the optimal path finding has a significant role to upgrade and guide the arm movement. the essential function of path planning is to create a path that satisfies the aims of motion including, averting obstacles collision, reducing time interval, decreasing the path traveling cost and satisfying the kinematics constraints. in this paper, the free cartesian space map of 2-dof arm is constructed to attain the joints variable at each point without collision. the d*algorithm and euclidean distance are applied to obtain the exact and estimated distances to the goal respectively. the modified particle swarm optimization algorithm is proposed to find an optimal path based on the local search, d* and euclidean distances. the quintic polynomial equation is utilized to provide a smooth trajectory path. according to the observe results, the modified pso algorithm is efficiently performs to find an optimal path even in difficult environments. keywords: d*, free cartesian space, path planning, particle swarm optimization (pso), robot arm. 1. introduction a robot arm is spontaneously controlled manipulator which possesses programming capacity into three or more axes with multipurpose uses in various automation implementations. the main issue for attaining autonomous robots arm is the planning for a collision-free path. however, in environments that comprise static or moving obstacles including human workers and other robots, path planning concerns in finding the possible path from the initial to the target configurations, providing that no point in the motion trajectory nor on the links of the arm collides with any obstacle, and ensures the shortest path [1,2]. with ideal system of path planning, navigation of robot arm can be achieved on its own with no human interference [3]. the path can be constructed either in the joint space or cartesian space. in the joint space, the path is particularly identified for each distinct joint, however, the end-effector cartesian position is only predicted at the start and target positions. moreover, the cartesian path has the characteristic of being easily specified, and the manipulator motion is entirely identified [4]. depending on the availability of information related to the robot arm environment, the path planning is subdivided into global and local path planning. the global path planning has the whole required information, in contrast, the local path planning has partially or entirely anonymous information [3]. motion planning possesses many algorithms that can be categorized into classical and heuristic. artificial potential field, visibility graph, and cell decomposition and many others are various forms of the classical approaches. each one faced the problems of local minimum stacking and has ahmed t. sadiq al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 2737 (2017) 28 elevated account of cost and time. on the other hand, the heuristic techniques are mainly utilized for their ability to solve the problem of path planning, and offer many advantages such as easiness in implementation and swift generation of various approved solutions [3, 5]. particle swarm optimization is a heuristic technique. simplicity, rapid convergence, power and impose few tuned parameters are the main features that differentiated it on the other complex optimization algorithms [5]. in this paper, the modified pso algorithm is proposed depending on cost of d* and euclidean distance to find an optimal path of two links arm that moved in 2d. 2. a review of previous researches in order to solve robot navigation problem, numerous methods have been proposed by many researchers. recently, a series of intelligent ideas are used, such as genetic algorithm, ant colony optimization and particle swarm optimization due to their ability for simultaneous calculations and efficient solving the navigation problems. guo et al [6] proposed the cultural based pso (cbpso) algorithm which is to find the collision-free trajectory for redundant robot manipulators in the presence of fixed obstacles. the authors used quadrinomial and quintic polynomials to describe the segment of the trajectory. rokbani and alimi [7] applied the inverse kinematics pso (ik-pso) to find the inverse kinematics of robot manipulator. the objective is to generate the trajectory path by forward kinematics depending on the joint variables that obtained from ikpso. kim and lee [8] proposed the pso algorithm based on a normalized step cost (nsc) for trajectory optimization. a nsc approach was considered as new method for initializing the particles in pso .the optimal trajectory is the one that had a lower cost and converged faster, without any collision with the obstacle in the workspace. 3. kinematics modeling of two-link robot arm kinematics is geometry of motion. kinematic problems can be classified into two types, one of them is the forward kinematic problem which is to allocate the position of end effector and its orientation through the provision of the values for the robots' joint variables, while the second problem is inverse kinematic which is specified all possible sets of joint angles and link geometries through provision the value of end effector position and orientation. the general purpose of using inverse kinematics is to obtain joint space through a given cartesian space (position and orientation of a manipulator end-effector) [9, 10]. in 2-dof planner manipulator, the geometric solution approach of inverse kinematics is used for obtaining the joint variables for all the points in cartesian space regardless their orientation [11, 12]. consider the diagram of fig. (1). the following equations are used to compute ��and �� [11, 12, 13]. fig. 1. two-link arm. cos �� = �� ��������� ����� = � … (1) since, the sin �� is sin �� = √1 − ���� … (2) the two possible solutions for �� can be obtained by writing as: �� = tan��( √������ � ) ... (3) finally, ��can be found by the following equation: �� = tan���� ! " − tan�� �� #$% &� ����� '(# &� … (4) where )� and )� are length of first and second links respectively [11, 12, 13]. the main advantage of this approach is to recapture both of the elbow-up and elbow-down solutions by choosing the negative and positive signs in the equation [13, 14, and 15]. the inverse kinematics can be considered as the first step for generate the free cartesian space on it the path planning algorithm is searching to find optimal path. ahmed t. sadiq al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 2737 (2017) 29 4. free cartesian space analysis in this paper, workspace space has been compiled and analyzed based on the inverse kinematics result. the free cartesian space of twolink arm can be defined as space with set of all points that can be reached by specific end-effector configurations. these points associated with joint angle (�� and��) which has been obtained from inverse kinematics. in environment contains many obstacles, the shape and volume of free cartesian space are varied according to the shape, size, position, and number of obstacles in addition to mechanical limits of joints (for the proposed method, modeling and simulation as in table 1). these constraints influence and restrict motion of manipulator as well as separate the workspace into reachable area and unreachable area. table 1, range of two joints for arm's links. link number range of arm's joint in degree joint 1 0 ≤ �� ≤ 360 joint 2 -90 ≤ �� ≤ 90 computation of the free cartesian space has been done by analyzing points in environment and finding all possible solution of point's configuration after checking both limitation of joint and collision with obstacles. the checking function is varied according to shape of the obstacle (polygon, circle). in polygon obstacle it is dependent on vertices positions of obstacle but in circle obstacle it is depending on center point as well as radius. moreover, there are three possible cases for each coordinates point in cartesian space. in the first case, the point has two solutions (elbow up and elbow down configurations) as shown in fig. (2). but in the second case, the point has just one solution either the manipulator is fully extended to reach a point at the border of manipulator's reachable workspace, or point has one configurations (elbow up or elbow down) due to the other configuration collide the obstacle at any part of manipulator links. while the in the third case, the point has no solution when coordinates point are out of reach of manipulator or in obstacles area, or the two configurations collide with obstacle at any part of arm links. fig. 2. two-link arm elbow up and elbow down configurations. the results of analysis points have been formed as three spaces, the first space is representing all points that reachable in elbow up solution (free elbow up space), and the second space is representing all points that have elbow down solution (free elbow down space), and the third space is unreachable space which including points outside the manipulator reachable workspace and points that collide with obstacle and points in obstacle area. moreover, the free cartesian space is comprising of all points have at least one solution (elbow up solution space and elbow down solution). the length of link of arm is also can be considered as major factor to construct the free cartesian space. 5. particle swarm optimization pso is technique of stochastic optimization, which operates on a principle that simulates the social behavior of the bird flocking. this technique are used in many applications and fields to recognize the parameters required for minimizing or maximizing [16, 17]. in a pso system, the individuals' swarm that are flying through the search space called particles and each particle is considered as a candidate optimal solution for the problem. the best position visited by a particle is influencing the particle position and the position of the best particle in its neighborhood i.e. its own and neighboring particles experiences respectively [16, 17]. various pso models have been evolved depending on the topology of neighborhood, namely: local best (lbest) and global best (gbest). when the whole swarm represents the ahmed t. sadiq al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 2737 (2017) 30 neighborhood of a particle, the global best position of the particle is considered as the best position in the neighborhood, in this case the gbest pso is the resulting algorithm. while the lbest pso algorithm can commonly be assigned when smaller neighborhoods are used, and the best particle is tracked by each particle which is gained by the particle local topological neighborhood. the fitness function is used to measure the performance or the activity of each particle. this function is differed according to the optimization problem. each particle in the swarm has characteristics as follows: (*+,-. ) is referred to the particle current position, (/0)-.) is referred to the particle current velocity and (*10,2-.) is referred to the particle personal best position. the best position reached by the particle i is referred as the personal best position of particle i, while the best position reached by all particles is referred as the global best position of particles (310,2-.) [17, 18, 19]. the pso algorithm run on the following principle: at first the particles are initialized with randomly distributed position within the workspace. furthermore the velocity of these particles is also assigned randomly. each particle has a memory that stores all the best previously visited positions in addition to the fitness function in that position which is improved over time. at each iteration of pso algorithm, *+,-. and /0)-. vector of particle is modified over each dimension j by using the equations (5 and 6) in order to guide these particles toward either the personal best vector or the swarm’s best vector [2, 17]. /0)-.4�� = 5 × /0)-.4 + 8� × 9� × �*10,2-. − *+,-." + 8� × 9� × �310,2-. − *+,-." … (5) *+,-.4�� = *+,-.4 + /0)-.4�� … (6) where 8� and 8� are the cognitive coefficients (8�+8�<=4), *10,2-. is the personal best vector, and 310,2-. is the swarm’s best vector. 9� and 9� are random real numbers between 0 and 1, while the inertia weight 5 controls the particle momentum, it is decreases from (5:;< = 0.9 to 5:-= = 0.4) over the whole run according to next equation [2, 17]: 5 = 5:;< − >?@ �>?ab $cdefc$(%?@ ∗ h20ij2h+k_kmn… (7) if the value of /0)-. is less than /0):-=or greater than /0):;< then the corresponding value is replaced by /0):-= or /0):;< , respectively. where /0):;< is maximum velocity parameter [2, 20, 17, 18]. 6. d* algorithm the d* also called " dynamic a*" algorithm is used to analyzed the environment. the arcs cost is dynamically changed at algorithm runs. each node to be assessed by d*algorithm is preserved in an open list with one of varied conditions (new, open, closed, raise, lower). d* algorithm is working by backward searching that begins from the goal point until reaching the start point via repeatedly choosing a node from open list for evaluation and computing its cost to the goal. then this node is expanded to the eight neighboring nodes in order to transmit its changes to these nodes and they eventually placed in the open list with a minimum cost. nevertheless, in the robot arm environment, only nodes belong to free cartesian space are evaluated to place them in open list. while, the rest is ignored. moreover, every expanded node possesses a backpointer and precise cost to the goal according to an equation (8). o = 3 + ℎ … (8) where the f is objective function and 3 is the estimated cost from star point while ℎ is the cost to the goal. this algorithm uses the heuristic function for increasing and reducing the propagate cost and focus cost respectively [21]. 7. proposed methodology to solve the path planning problems for twolink arm, the modified lbest pso algorithm is proposed to generating the collision free path. the lbest pso algorithm is locally searching through work space (free cartesian space ) depending on d* and euclidean distance costs to find arm optimal path from its start to goal configurations according to several steps. in the premier step the start node with initial velocity equal to zero is considered as current position and its eight neighborhood nodes (particles) are determined to be tested by lbest pso algorithm. in which only the nodes belonging to free cartesian space are tested by applying the velocity equation (5), where 310,2-. indicate to the minimum d* cost (at eight tested neighborhood nodes), *+,-. indicate to the d* cost at tested node, and *10,2-. indicate to the euclidean distance (s) from tested node to the goal node that is depending solely on the direct orientation to the goal and can be computed for every point in the free cartesian space according to following equation (9). ahmed t. sadiq al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 2737 (2017) 31 s = t( − u)� + (� − �u)� … (9) where the ( , � ) represent the x-y coordinate of the free cartesian point and ( u , �u) represent the x-y coordinate to the goal point. the coefficients 9� and 9� have significant role to guide the solution either toward the node with minimum d* cost or toward the node with minimum euclidean distance. then only one particle with minimum cost and high probability is selected to be at the current node in the proposed path. in case of the current node does not possess tested neighborhood nodes belong to the free cartesian space, then the node is considered as dead point and pso algorithm has to be returned to the last node in the path for selecting another node. while in the next step the new velocity for each particle (potential solution) is set depending on its prior velocity /0)-.4 . the lbest pso repeatedly generate and test eight neighborhood nodes for current node until reaching the goal point and the proposed path is considered as the candidate optimal path. this process is iterated until a specific number of iterations are achieved or minimum cost is obtained. finally the optimal path is formed from entire iterations via selecting the best candidate solution with the minimum cost function which can be calculated by the following equation: cost=∑ x( − -��)� + (�− �-��)�:-y� ... (10) where, m is the number of particles which is equal to the number of nodes along the path, ( , �-) represents the current position of ith particle. depending on the number of the grid, the optimal path may be more than one path. each path has the same cost but with differences in some points. all process is done as in the flowchart shown in figure (3). 8. path smoothing using quintic polynomial equation trajectory can be defined as path which be followed by a moving manipulator through work space at specific time. amount of time on which trajectory is carried out can be determined as ( 2z 2[). since the velocities and accelerations are also parameterized by time, they can be calculated along the trajectories by differentiation with respect to time. the set of quintic polynomial trajectory equations includes a fifth order polynomial position equation, the first derivative is a fourth order velocity equation and the second derivative is a third order polynomial acceleration equation. the trajectory has six constraints which is as initial and final for each one of configurations, velocities and accelerations [14]. \(2) = j[ + j�2 + j�2� + j]2] + j^2^ + j_2_ … (11) according to equation (11) at time 2[, the initial position, velocity and acceleration equations are: \(2[) = \` … (12) \a (2[) = /` … (13) \b (2[) = j` … (14) where (\` , /` , j`) representing the initial position, velocity and acceleration respectively [14]. while at time tc the final position, velocity and acceleration equations are: \�2z" = \u … (15) \a (2z) = /u … (16) \b (2z) = ju … (17) where (\u , /u , ju) represent the target position, velocity and acceleration respectively [14]. depending on appropriate number of derivatives for equation (11), the following equations are obtained: q[ = a[ + a�t[ + a�t[� + a]t[] + a^t[̂ + a_t[_ … (18) v[ = a� + 2a�t[ + 3a]t[� + 4a^t[] + 5a_t[̂ … (19) α[ = 2 a� + 6a]t[ + 12a^t[� + 20a_t[] … (20) qc = a[ + a�tc + a�tc� + a]tc] + a^t ĉ + a_tc_ … (21) vc = a� + 2a�tc + 3a]tc� + 4a^tc] + 5a_t ĉ ... (22) αc = 2 a� + 6a]tc + 12a^tc� + 20a_tc] … (23) according to quintic polynomial trajectory planning, the optimal path that is generated by lbest pso is smoothed by randomly selected of via points from this path as well as start and goal points. these via points are connecting depending on equations (14, 18, 19, 20 and 21) at ( 2z2[). the result from this stage is the optimal smoothing path from \` to \u. 9. results and discussion in this paper, the proposed method was tested by using matlab program (2015a) with a difficult proposed map and has a limited from (-50 to 50) cm for both x-y dimensions. the length of ahmed t. sadiq al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 2737 (2017) 32 start calculate the inverse kinematic to obtain free cartesian space initialize the start point (current point) with zero velocity determine the eight neighborhood nodes as population generation ) particles (for current point and ignored node out of free cartesian space apply velocity equation(5) to the each particles positions update the position equation(6) by selecting the particle with the minimum cost fitness is each to goal? evaluate the cost fitness function to candidate optimal path is max iteration achieved? selecting the individual optimal path with minimum cost fitness function generating smoothing trajectory path end no yes yes no fig. 3. flowchart of modified pso. the robot links for both link1 and link 2 is proposed equal to 25 cm. initially, the proposed environment was analyzed and its elbow up and elbow down solutions are computed by using inverse kinematics equations (1, 2, 3, and 4). the free elbow down space is constructed by using the solution of inverse kinematics with the negative sign of equations (3, 4) and ensuring no collision with obstacles, as shown in figure (4, a). while the free elbow up space is constructed by using the solution of inverse kinematics with the positive sign of equations (3, 4) and ensuring no collision with obstacles, as shown in figure (4, b). ultimately the free cartesian space map is constructed by all the reachable points in elbow up and elbow down configurations figure (5). (a) (b) fig. 4. (a): two-link robot manipulator elbow down configuration solution, (b): two-link robot manipulator elbow up configuration solution. ahmed t. sadiq al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 2737 (2017) 33 fig. 5. two-link robot manipulator free cartesian space. in figures (4, 5), the small dots denoted the free cartesian space reachable points while the black big circles referred to the proposed obstacles with 5 cm radius, and the white space denoted either unreachable points due to the collision with the obstacle or due to robot joints limit. it is a crucial that the start and goal task are part of free cartesian space, otherwise no path can be planned by the arm, therefore, it is of importance to check the initial and target configurations for the arm offline before running the algorithm. once the cost functions for each point in free cartesian space were computed by d* algorithm and euclidean distance, the modified algorithm was run with the following proposed parameters: initial velocity = 0, the coefficients 8� = 3, 8� = 1 in order to guide lbest pso toward the high probability of d* value, initial 5 = 0.4 and max iteration number = 300. in this proposed method, one or more optimal path may be presented. moreover, these paths have the same cost with difference in some middle points. the optimal path from the start point (40, 10) to the goal point (-45,-15) with a cost fitness of 92.6232 and executed for 78s is shown in the figure (6). figure (7) illustrates the smooth trajectory path that is computed by using the quintic polynomial trajectory equations from 2[ = 0 sec and 2z = 10 sec. figure (8) demonstrates the arm tracking for the optimal path where the red and green links represent the link1 and link2 of the arm respectively. -50 -40 -30 -20 -10 100 4020 30 50 x,cm y ,c m two-link robot arm path planning using pso algorithm -50 -40 -30 -20 -10 10 0 40 20 30 50 fig. 6. pso optimal path solution. -50 -40 -30 -20 -10 100 4020 30 50 -50 -40 -30 -20 -10 10 0 40 20 30 50 two-link robot arm path planning using pso algorithm x,cm y ,c m fig. 7. quantic polynomial trajectory path optimal solution. two-link robot arm path planning using pso algorithm x,cm -50 -40 -30 -20 -10 10 0 40 20 30 50 -50 -40 -30 -20 -10 100 4020 30 50 y ,c m fig. 8. two-link robot manipulator optimal path. ahmed t. sadiq al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 2737 (2017) 34 the next figures (9, 10, 11, and 12) show the results of changing the x, y, theta 1 of first link and theta 2of second link of the optimal smoothing path during 10s. 1 2 3 4 5 6 7 8 9 10 time (s) -50 -40 -30 -20 -10 10 0 40 20 30 x ,c m two-link robot arm path planning using pso algorithm fig. 9. the change of x coordinate of optimal path. 1 2 3 4 6 7 8 9 10 time (s) 5 10 5 0 -5 -10 -15 y ,c m two-link robot arm path planning using pso algorithm fig. 10. the change of y coordinate of optimal path. 1 2 3 4 5 6 7 8 9 10 -4 -3.5 -3 -2.5 -2 -1.5 -1 -0.5 0 two-link robot arm path planning using pso algorithm time (s) t h e ta 1 ( “ ra d ” ) fig. 11. the change of theta 1 of optimal path. 1 2 3 4 5 6 7 8 9 10 time (s) 0.5 1 2 1.5 2.5 3 t h e ta 2 ( “ ra d ” ) two-link robot arm path planning using pso algorithm fig. 12. the change of theta 2 in optimal path. another task was tested by the same proposed mapping but different in the start and goal points. the path is from the start point (30, -30) to the goal point (15, 45), where its cost fitness is 82.8733 and executed for 49s, as shown in figure (13, 15), and smoothing path shows in figure (14). -50 -40 -30 -20 -10 100 4020 30 50 y ,c m two-link robot arm path planning using pso algorithm x, cm -50 -40 -30 -20 -10 10 0 40 20 30 50 s fig. 13. pso optimal path solution. -50 -40 -30 -20 -10 100 4020 30 50 y , c m two-link robot arm path planning using pso algorithm x, cm -50 -40 -30 -20 -10 10 0 40 20 30 50 fig. 14. trajectory path optimal solution. ahmed t. sadiq al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 2737 (2017) 35 -50 -40 -30 -20 -10 100 4020 30 50 y , c m x, cm two-link robot arm path planning using pso algorithm -50 -40 -30 -20 -10 10 0 40 20 30 50 fig. 15. two-link robot manipulator optimal path, where the red line denoted the link 1 of arm while the green line denoted the kink2 of arm. figures (16, 17, 18, and 19) clarifies the results of changing the x, y, theta 1 of first link and theta 2of second link of the optimal smoothing path during 10s. 1 2 3 4 5 6 7 8 9 10 time (s) 5 10 20 15 25 30 x , c m two-link robot arm path planning using pso algorithm fig. 16. the change of x coordinate of optimal path. 1 2 3 4 5 6 7 8 9 10 time (s) -30 -20 -10 0 20 10 50 30 40 y , cm two-link robot arm path planning using pso algorithm fig. 17. the change of y coordinate of optimal path. 1 2 3 4 5 6 7 8 9 10 two-link robot arm path planning using pso algorithm time (s) t h e ta 1 ( “ ra d ” ) 2.5 2 1.5 1 0.5 0 -0.5 fig. 18. the change of theta 1 of optimal path. 1 2 3 4 5 6 7 8 9 10 time (s) -3 -2.5 -1.5 -2 -1 -0.5 t h e ta 2 ( “ ra d ” ) two-link robot arm path planning using pso algorithm fig. 19. the change of theta 2 of optimal path. 10. conclusion for solving the path planning problem and to find the optimal path of the robot arm, the modified pso algorithm is proposed. the free cartesian space with free elbow up solution space and free elbow down solution space are initially constructed by using the inverse kinematics. in this paper pso is proposed to find the shortest path depending on the costs of d* and euclidean distance. the modified algorithm efficiently finds the optimal path by locally searching and computing the probability to all possible solutions of robot arm end effector position and takes the best one to form the path. more specifically, (8) and (9) equations are playing an important role in providing high diversity to the possible solutions. finally, the quintic polynomial equation is integrated with pso for smoothing the path at specific time. ahmed t. sadiq al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 2737 (2017) 36 by comparison with reference [6] that based on cbpso algorithm to find the near-optimal path for the robot manipulator in the joint space, the results from the table below clearly confirm that the proposed algorithm of modified pso based on d* algorithm has better performance in any two-link robot environment. the proposed method has the ability for finding the optimal shortest path solution in many easy and difficult environments. table (2) shows test data of computation time (s) generated by cbpso and d* based pso algorithms, corresponding to the different number of obstacles existence workspace types of the workspace and optimality of the generated path. table 2, the comparison of different algorithms. cbpso algorithm d* based pso computation time(s) 64.65 63.5 number of obstacles less than 4 more than 4 workspace joint space cartesian space optimality of the path near to optimal optimal shortest path in contrast, it is possible to observe some ambiguity in the performance of the proposed algorithm in online path planning process with static and dynamic obstacles. 11. reference [1] kelly r., santibanez v. and loria a. (2005), "control of robot manipulators in joint space", springer, heidelberg, new york, hong kong, london, milan, paris, tokyo. [2] rakibul islam and tajmiruzzaman (2014), "autonomous robot path planning using particle swarm optimization in dynamic environment with mobile obstacles & multiple target", icmiee, bangladesh. [3] ahmed t. sadiq, a. h. h.(2013),"swarm robot path planning using hybrid pso with d* algorithms in dynamic environment", iraq. [4] ata, a. a.( 2007),"optimal trajectory planning of manipulators",journal of engineering science and technology, vol. 2. [5] shahab a., m. usman rafique, and m. umer khan (2015)," mobile robot path planning in static environments using particle swarm optimization", international journal of computer science and electronics engineering (ijcsee), vol. 3. [6] chao and liu (2012), " modelling and optimization approach for trajectory planning of three freedom planar manipulators", journal of pure and applied mathematics: vol. 7, no.1, pp. 1-20. [7] rokbani and alimi (2013)," inverse kinematics using particle swarm optimization, a statistical analysis", procedia engineering, vol. 64. [8] kim and lee (2015)," trajectory optimization with particle swarm optimization for manipulator motion planning", ieee transaction on industrial informatics. [9] craig, j. j. (1989)," introduction to robotics", addison-wesley. [10] wesam mohammed (2011)," solution of inverse kinematics for scara manipulator using adaptive neuro-fuzzy network", ijsc, vol.2, no.4. [11] cubero s (2006)," industrial robotics theory modelling control", isbn. [12] richard m., zexiang li and s. shankar (1994),"mathematical introduction to robotic manipulation". [13] m. o’malley (2011), "introduction to robotics, inverse manipulator kinematics", international journal on soft computing (ijsc) vol.2, no.4. [14] w. spong, seth hutchi nson, and m. vidyasagar (2005), robot modeling and control,1st ed, wiley. [15] carl d. iii crane. by joseph duffy (2009), "kinematic analysis of robot manipulators", cambridge university press. [16] ahmadzadeh s. and ghanavati m. (2012)," navigation of mobile robot using the pso particle swarm optimization", journal of academic and applied studies, vol. 2, pp. 32-38. [17] s.n.sivanandam and p.visalakshi (2007), "multiprocessor scheduling using hybrid particle swarm optimization with dynamically varying inertia", international journal of computer science & applications, vol. 4 issue 3, pp. 95-106. [18] sanjay sarma o v, vishwanath lohit t and deepak jayaraj (2012), "path planning in swarm robots using particle swarm optimization on potential fields", international journal of computer applications, vol. 60. [19] xin chen and yangmin li. (2006), “smooth path planning of a mobile robot using stochastic particle swarm optimization", in proceedings of the ieee international conference on mechatronics and automation, pp.1722-1726. [20] shi .p and y. zhao (2009), "an efficient path planning algorithm for mobile robot using improved potential field", in ieee international conference on robotics and biomimetics, pp. 1704-1708. [21] nosrati m., karimi r. and hasanvand h. (2012)," investigation of the d * (star) search algorithms: characteristics, methods and approaches", world applied programming, vol. 2, no.4. )2017( 27-37، صفحة 3د، العد13دجلة الخوارزمي الهندسية المجلم احمد طارق صادق 37 *dعلى خوارزمية إعتماداً تقنية سرب الطيور المعدلة باستخدامتخطيط المسار لذراع الروبوت راس عبد الرزاق رحيم** نور الهدى فضل عباس***فاحمد طارق صادق* الجامعة التكنولوجية /علوم الحاسوبقسم **،** الجامعة التكنولوجية /قسم السيطرة والنظم** drahmed_tark@yahoo.com :البريد االلكتروني* dr.firas7010@yahoo.com :**البريد االلكتروني nooralhudafabbas92@yahoo.com ***البريد االلكتروني: الخالصة بالغ له دور للذراع لذلك فان إيجاد المساراالمثلوحظي ذراع الروبوت مؤخرا بالكثير من االهتمام نظرا الستخداماته المتعددة في مختلف التطبيقات. هداف الحركة والمتضمنة: تجنب أل ملبيال المسارالمسار في البحث عن لتخطيط االساس المهمةوتتمثل . وتوجيهها االهمية في تحسين حركات الذراع يزي الحر لذراع ثنائي الكارت هيكلة الفضاء تم البحث،الحركة، تقليل تكلفة المسافة وتحقيق القيود الكينماتيكية للذراع. في هذا زمن وخفضاالصطدام بالعوائق، المسافة اإلقليدية ومعادلة *dمن خوارزمية لاستخدام كل عنفضالوالذي يضم جميع قيم المفاصل بضمانة عدم االصطدام بالعوائق. الحركة،درجات حرية لى ع اعتماداالمعدلة للبحث عن المسار االمثل محليا السرب خوارزمية واقتراحللحصول على المسافة الدقيقة والمسافة المقدرة عن الهدف على التوالي. ومعادلة المسافة اإلقليدية. وقد تم استخدم المعادلة المتعددة الحدود من الدرجة الخامسة بغية الحصول على مسار سلس *dالمسافات المستخلصة من خوارزمية وفي ظل بيئات صعبة ومعقدة. المسار األمثلتبحث بكفاءة عن المعدلة السربمحددة. ووفقا للنتائج المستخلصة، فأن خوارزمية زمنه مدةفي 45-60 al-khwarizmi engineering journal,vol. 12, no. 1, p.p. design of a kinematic neural enhanced hybrid firefly nizar hadi abbas *,**department of electrical (received abstract the paper present design of a control structure that enables integration of a kinematic neural controller for trajectory tracking of a nonholonomic differential two wheeled mobile robot, controller to direct a national instrument mobile robot (ni mobile robot). the controller is to make the actual velocity of the wheeled mobile robot close the required velocity by guarantees that the trajectory tracking mean squire error converges at minimum tracking error. the proposed tracking control system consists of two layers; the first layer is a multi-layer perceptron neural network system that controls layer is an optimization layer ,which is implemented colony (cfa-abc) to tune the controller's optimization algorithm is verified by various benchmark functions cfa and (cfa-abc ) are better than the original effectiveness of the proposed algorithm tracking results with two reference trajectories (circular and keywords: mobile robot, trajectory tracking, algorithm, artificial bee colony algorithm. 1. introduction in recent years a plethora of research has been carried out on the control problem of the mobile robotic systems. this is mainly due to the growing application of these systems both in industrial and service environments [1].intelligent wheeled mobile robots are the subject of the technical interest arising from possibility of practical application in: manufacturing, civil engineering, transportation, agriculture, space exploration, deep sea penetration, help for disable, medical surgery and in the other sectors of science and technology [2]. the pathing control problems of a nonholonomic wheeled mobile robots have attracted considerable attention, there are two obvious approaches tracking control problems: trajectory tracking and path planning proposed a method to design a trajectory khwarizmi engineering journal,vol. 12, no. 1, p.p. 4560 (2016) kinematic neural controller for mobile robots based on enhanced hybrid firefly-artificial bee colony algorithm abbas* basma jumia saleh ** electrical engineering / college of engineering/ university of baghdad * email: drnizaralmsaodi@gmail.com **email: eng.basmaj@gmail.com (received 6 april 2015; accepted 21 october 2015) the paper present design of a control structure that enables integration of a kinematic neural controller for of a nonholonomic differential two wheeled mobile robot, then proposes a kinematic neural direct a national instrument mobile robot (ni mobile robot). the controller is to make the actual velocity of the wheeled mobile robot close the required velocity by guarantees that the trajectory tracking mean squire error . the proposed tracking control system consists of two layers; the first layer is a layer perceptron neural network system that controls the mobile robot to track the required path , the second layer is an optimization layer ,which is implemented based on hybrid crossoved firefly algorithm with artificial bee controller's parameters to achieve the optimal path. the performance of the hybrid s verified by various benchmark functions. the simulation results show that abc ) are better than the original firefly algorithm. a simulation example is given to indicate the algorithm, the results have been done using matlab (r2013b), tracking results with two reference trajectories (circular and lemniscates ) are presented. mobile robot, trajectory tracking, neural networks, kinematic controller, national instrument, firefly algorithm, artificial bee colony algorithm. in recent years a plethora of research has been on the control problem of the mobile robotic systems. this is mainly due to the growing application of these systems both in industrial and intelligent wheeled mobile robots are the subject of the technical ossibility of practical civil engineering, transportation, agriculture, space exploration, deep sea penetration, help for disable, medical surgery and in the other sectors of science and the pathing control problems of a wheeled mobile robots have considerable attention, there are two control problems: and path planning. kanayama to design a trajectory tracking controller that meet a specific requirements. therefore, for the trajectory kinematic model are suggested to close the target control objective [3]. various control systems have been in order to serve as a robust con mobile robot systems. the control algorithm of any mobile robot depends either on the dynamic model or the kinematic model of the mobile robot this research depends on kinematic controller, the main purpose of the kinematic controller is to out a near-optimum velocity for the mobile robot in order to reduce the error between the path and the reference path of the mobile robot system [4]. this paper deal with the use of the neural networks (anns) learning and adaptation capabilities one of the almost popular intelligent techniques generally applied in engineering for al-khwarizmi engineering journal (2016) robots based on algorithm saleh ** university of baghdad the paper present design of a control structure that enables integration of a kinematic neural controller for then proposes a kinematic neural direct a national instrument mobile robot (ni mobile robot). the controller is to make the actual velocity of the wheeled mobile robot close the required velocity by guarantees that the trajectory tracking mean squire error . the proposed tracking control system consists of two layers; the first layer is a required path , the second firefly algorithm with artificial bee the optimal path. the performance of the hybrid n results show that the utilizing of . a simulation example is given to indicate the (r2013b), and all trajectory neural networks, kinematic controller, national instrument, firefly controller that meet a specific requirements. therefore, for the trajectory tracking problem the kinematic model are suggested to close the target various control systems have been enhanced a robust control rule for mobile robot systems. the control algorithm of any mobile robot depends either on the dynamic matic model of the mobile robot. depends on kinematic controller, the purpose of the kinematic controller is to find velocity for the mobile robot in order to reduce the error between the required path and the reference path of the mobile robot this paper deal with the use of the artificial (anns) because of their ing and adaptation capabilities. anns are popular intelligent techniques applied in engineering for systems nizar hadi abbas al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 4560 (2016) 46 which are time variant. additionally, their ability to learn complex input-output mapping, without detailed analytical model, approximation of nonlinear function and robustness for noise environment make them an ideal choice for real implementations [5]. furthermore, its lateral structure makes the neural network achievement rapid than the achievement of other classical artificial intelligence techniques such as a genetic algorithm. in engineering problems, the optimization is to find out a solution that can maximize or minimize an objective function. nowadays, stochastic method is more often used to deal with optimization problems [6]. though there are several ways to organize them, a simple one is used to divide them into two groups conforming to their nature: deterministic and stochastic. deterministic algorithms can bring the same solutions if the initial conditions are unaffected, because they always follow the accurate move. however, disregard of the initial values. stochastic ones are based on convinced stochastic distribution; therefore they generally generate many solutions. in fact, both of them can find satisfactory solutions after some generations. recently, nature-inspired algorithms are prove its capability in solving numerical optimization problems more comfortably. these metaheuristic ways are developed to solve difficult problems, such permutation flow shop scheduling [7], reliability, high-dimensional function optimization , and other engineering problems .nowadays, many other metaheuristic methods have occurred, like ant colony optimization (aco) , harmony search (hs), particle swarm optimization (pso), firefly algorithm (fa) , and artificial bee colony (abc) [8]. 2. kinematic model of differential wheeled mobile robot the aim of the wheeled mobile robot kinematic model is to find the mobile robot velocity in the inertial body as a function of the wheels velocities and the configuration coordinates of the robot. i.e. authorized the robot speed �� = [�� �� �� ] as a function of the wheel translational velocities ��� and �� . the mobile robot kinematics commonly has two main analyses, forward kinematics and feedback kinematics [10]: • forward mobile robot kinematics: ��� = ������� � = ����� , �� � …(1) • feedback mobile robot kinematics: ������ � = ���� , �� , �� � …(2) the graphic of the differential wheeled mobile robot model shown in fig. 1, consists of a cart with two standard wheels for motion on the same axis and castor wheel in the front of cart for stability. the castor wheel carries the mechanical format and keeps the robot more stable [8]. suppose a differential wheeled mobile robot structure which has two wheels with the radius of �� based with a length �1/2 from the mobile robot center: fig.1. the differential drive mobile robot model. at each instant in time, the left and right wheels follow a path as a show in fig. 2.7 that moves around the instantaneous center of curvature mobile robot (iccm) with the same angular rate [9]. fig. 2. the instantaneous center of curvature mobile robot. x-axis y-axis x y 2�l1 c θ nizar hadi abbas al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 4560 (2016) 47 ω� � = !"�#�!# …(3) thus: $� � = ω� ��%� � …(4) $ � � = &rc� � + *+ ,ω� � …(5) $�� � = �rc� � − *+ � ω� � …(6) after solving equations 2.3 and 2.4, then find the instantaneous center of curvature mobile robot (iccm) trajectory relative to the mid-point axis (c) is given as equation 2.5 [9]. �%� � = * �./�#�0.1�#��+ �./�#�2.1�#�� …(7) the angular velocity of the mobile robot is [11]: ω� � = �./�#�2.1�#�� * …(8) and the linear velocity of the mobile robot is [11]: $� � = �./�#�0.1�#��+ …(9) it is simulated that the wheeled mobile robot below the nonholonomic constraint, which is ideal rolling no skidding [11], as shown in (2): − ��( � 345� ( ) + �� ( � %63� ( ) = 0 … (10) the kinematics equations of differential wheeled mobile robot is represented as follows [11]: ��� � = $� �cos�� � … �11� ��� � = $� �sin�� � ... (12) ��� � = ω� � … �13� in order to obtain the position and orientation of the wheeled mobile robot, it is required to integrate equation as showed below [12]: �� � = �== + > $� �cos�� �? #= … (14) �� � = �== + > $� �sin�� �? #= … (15) �� � = �== + > ω� �? #= … (16) in the computer simulation , the form of the pose (position/orientation) equations as follows[11]: ����� = 0.5[$���� + $ ���]%63����∆d +��� − 1� … (17) ����� = 0.5[$���� + $ ���]345����∆d +��� − 1� … (18) ����� = 1�� [$���� + $ ���]∆d + ��� − 1� … (19) where �����, �����, ����� are the elements of the pose (position/orientation) at l and ∆ . 3. the trajectory tracking controller the suggested building of the nonlinear kinematic neural controller may be addicted in the style of block diagram, as shown in fig. 3. the access to control the wheeled mobile robot build upon the accessible information of the unknown nonlinear system and also be known by the inputoutput information and the control design. the hybrid crossoved firefly with artificial bee colony (cfa-abc) optimization will produce the optimal parameter for the kinematic neural controller to get best velocity control signal that will minimize the pathing error of the mobile robot. the feedback kinematic controller is vital to keep the trajectory pathing error of the wheeled mobile robot system when the path of the robot obtained from the required trajectory event transient state. the exploration of the wheeled mobile robot starts with generating the desired trajectory where �e = [�e , �e , �e] is the desired pose (position/ orientation) of the wheeled mobile robot [11]. this desired pose (position/ orientation) is used by the feedback kinematic of the wheeled mobile robot to produce the needed linear and angular velocities for the described trajectory with the needed orientation. the error vector is then mathematical calculation by examining the desired pose (position/ orientation) of the wheeled mobile with the real pose of robot structure by using the rotational matrix. this error signal is then used by the controller to generate a control action to obligate the wheeled mobile robot to follow the desired path [11,12]. the kinematic illustrative of the wheeled mobile robot can be written in the model: f�� � �� � � ��� � �g=� cos ��� �� 0sin ��� �� 00 1� h $ωi ... (20) let ��e , �e�is the desired position of the wheeled mobile robot, and �e is the desired orientation of the wheeled mobile robot, so that the desired posture vector is �e = [�e, �e, �e] . the real position of the wheeled mobile robot is pretended to be ��, �� and the real orientation of the wheeled mobile robot is assumed to be �, so that the real posture of the mobile robot is �� = [�, �, �] . then the error j = [j�, j�, j�] can be calculated in the global modal: nizar hadi abbas al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 4560 (2016) 48 kj�j�j�l = ��e − ��e − ��e − �� … (21) the error vector e needs to be transformation into the wheeled mobile robot modal by using the rotation matrix ŗ [11]: the kinematic neural controller consists of two layer: neural network topology and optimization algorithms. 3.1 the first layer: neural network topology the neural network is an arithmetical model inspired by biological neural networks. a neural network made up of an interconnected collection of neurons, and it progresses information using a connectionist way to computation. the solution of problem of control wheeled mobile robot requires application of complex methods. because of lack of a systematic approach to analysis and synthesis of control of nonlinear systems so far , the artificial neural networks became an attractive tool used in theory of nonlinear systems. multilayer perceptron (mlp) neural networks owe their popularity to properties like: possibility of approxi jm = ŗ ∗ j kj�mj�mj�ml =f cos��� �� sin��� �� 0− sin��� �� cos��� �� 00 0 1g k j�j�j�l … (22) the error vector em is augment into the controller and at another time it is the accountability of the controller to generate the desired linear and angular velocities to minimize the error [12]. -mation of arbitrary nonlinear mappings, and ability of learning and adaptation [13, 14]. let as consider multi-layer perceptron (mlp) neural networks shown in fig.4. the number of the hidden layer nodes can be changed based on the required efficiency of the mlp neural network. the acceptable number of hidden layer nodes in the beginning can be taken equal to (2m+1) from [12]. the outturn of the mlp neural network is considering as follow: $��� − 1�, $ �� − 1�= ∑ ℎ5dr ∗ stuvuwx* − yz2 … (23) where hntj is the output of the hidden layer node j and is being considerate as: ℎ5dr = [�?r� … (24) where: ?r = ∑ 45\]d4v^^x* ∗ $u^ −yr1 … (25) the outputs of the mlp neural networks that can be reached from the activation function, which is bipolar sigmoid function is as follows: [�?r� = +*0_`j -1 … (26) the neural network weights (control parameter) vj ,wkj, yr1 and yz2 are adapted using optimization algorithms, describe as the next section [11]. 3.2 the second layer: optimization algorithm 3.2.1 firefly algorithm now delineated the primary parts of the firefly algorithm developed by xin-she yang at cambridge university [8] is briefly described. the fa is inspired from the flash model and features of fireflies. in order to describing the algorithm in the simple manner the following three idealised rules are used: 1) whole fireflies are unisex so that each firefly will be appealed to other fireflies careless of their sex. 2) appealingness is relative to their luminousness, thus for any two blinking fireflies, the less shinier one will move towards the shinier one. the appealingness is relative to the luminousness and they both reduction as their distance increments. if there is no shinier one than a appropriate firefly, it will be motion randomly. 3) the luminousness of a firefly is determined by the mural of the objective function. in the firefly algorithm, there are two significant events: the fluctuation of flash intensity and creation of the luminousness. for easiness, the luminousness of a firefly was determined by its shininess which in movement is related with the objective function. in the clear form, the flash intensity [�aa� changes consorting to the reverse square law([�aa� = bceed � [8]. for a given modal with a fixated flash absorption coefficient e, the flash intensity [ changes with the distance rr [22], that is [ = [=j2fee …(27) nizar hadi abbas al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 4560 (2016) 49 as a firefly's luminousness is relative to the flash intensity seen by neighboring fireflies, the luminousness g� of a firefly was specified by [8]: g� = g�=j2feed … �28� the distance between any two fireflies 41 and r1 at �i^* and �iu*, specifically, is the cartesian form [22]: a41r1 = j�i^* − �iu*j =k∑ ��i^*,l − �iu*,l�+!lx* …(29) where �i^,l is the mth component of the relating coordinate �i^ of ith firefly, in the 2-d case as shown in eq. (30), from [22]: aa41r1 = k��i^* − �iu*�+ + ��i^* −�iu*�+ … �30� the motion of a firefly 41 is appealed to another more shinier (brighter) firefty j1 by [22]: xlp* = xlp* + βl=e2tuuvwd �xlx* − xlp*� + α1 �rand − 0.5� …(31) where the second term is due to the attractive feature. the third part is randomisation with a hold parameter }1, which makes the investigation of the search distance more effective [15], after few imitations, use g= =1, }11 ∈ [0,1],e = 1,,for most operation. 3.2.2 crossover firefly algorithm (cfa) in standard firefly, if there no brighter one than a particular firefly, the fireflies will move randomly, and by using flat crossover algorithms the updating mechanism at each iteration by the coefficient delta is a uniform distributed random variable within optional interval [0,1]. the flat crossover coefficient (alpha) is defined as follows: �i\ℎ� = �?jid�� ∗ � �i\ℎ�^�_e��^�� � … �32� where alpha changing at each iteration. and the flat crossover operate based on the following equation: �i^*=��i\ℎ�� ∗ �iu* + �1 − �i\ℎ�� ∗ �ir1 …�33� instead of fireflies move randomly using the possibility of crossover, then the candidates for the best solution are increasing. on the other hand, fa become needs less time to search for the best solution and its performance significantly developments with the increases the population size because of decreasing the randomness. 3.2.3 artificial bee colony(abc)algorithm artificial bee colony (abc) algorithm invented by d. karaboga [20] is a relatively new population-based algorithm; it is a nature-inspired metaheuristic algorithm, which inspire the foraging action of bees. abc as a stochastic performance is clear to employment, and could easily be modified and hybridized with other metaheuristic algorithms [16]. in real colonies, including bees, some tasks are performed by specified individuals. these specified bees try to expand the nectar quantity stored in the hive using efficient organization. the abc algorithm simulation represented by three kinds of bees: employed bees, onlooker bees and scout bees. divided of the colony includes of employed bees, and the other half made up of onlooker bees. more bees should send to highquality sources, and fewer bees should be sent to low-quality sources or even deserted. at the starting, the colony sends employed bees to productive flower patches. these bees catch flower's nectar and take them to the hive. when they return to the hive, empty their nectar and go to a desired area in the hive called ‘dance floor’ to share their data with other bees. the connections is executed by a especial dance. if the place visited by an employee is adjacent, it executes "round dances" in the hive, and if not, the bee executes a "waggle dance". round dance include data about the nectar quality of a visited flower patches so the other bees can discovery its position by their smelling sense when they escape of the hive. waggle dance carries three parts of information about the flower patch: its guidance with regard to sun, its length from the colony, and the nectar quantity [17]. onlooker bees lookout the dances in the hive and select the good flower patches to go for. indeed, flower patches which have greater qualities appeal more bees than smaller quality flower patches. employed bees that their travelled to place is abandoned through low quality have two choices: start the dance floor and watch dances of other bees then go to a flower patch as an onlooker bee, or it search about the hive automatically as a scout bee for a new food source due to few inner inspiration or potential outer hint [18]. nizar hadi abbas al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 4560 (2016) 50 abc algorithm can be summarized as in the following subsections [18]: 3.2.3.1 population initialization a population of fm1 individuals is produced randomly, which is equalise to the number of food sources. each solution �i^*(i1 = 1, 2… [�1) describing an individual is a d1-dimensional vector. hither. each solution can be produced by eq. (34) [19]: �i^*u* = �iu*v^�+��iu*v��-�iu*v^��. a�5?�0,1� …(34) where 41� = 1,2,…… , [�1, r1� = 1,2,… . . , �1. next, the fitness of each food source is evaluated by �4d5j33 41 = � **0�^* 4� �41 ≥ 01 + |�41| 4� �41 < 0 � … (35) 3.2.3.2 employed bee stage at this stage, a new nominee solution �i^*u* is produced for the employed bee of food source �i^* (only one parameter of the solution is updated by using eq. (35) : �i^*u* = �i^*u* + ∅^*u*. ��i^*u* − �it*u*� …(36) where z1 ∈ [1… . [�1]�5? r1 ∈ [1… . . �1]are arbitrary numbers, and z1 has to be other from 41, ∅^*u*. after creating a new food source �i^u, it will be evaluated and compared with �i^*u* immediately. then a greedy selection action is applied by comparing the fitness of both solutions produced via eq. (35). if the fitness of solution �i^*u* is more well than or equal to that of the solution �i^*u*,, �i^*u* will be replaced with �i^*u* and the individual �i^*u*will become a new member of the population and ��6]5di^*�is reset. otherwise, food source �i^*u* is kept unchanged and ��6]5di^*�is increased by 1. 3.2.3.3 onlooker bee stage later all employed bees completed the looking for operation; each onlooker bee chooses an employed bee to improve its solution with a probability value, which is calculated by roulette wheel using eq. (37). \41 = �^��_�� ^*∑ �^��_�� ^*������� ... (37) where �4d5j33 41, which is correlative to the nectar quantity of that food source. apparently, the greater the 41 , the extra the probability of selecting the 41dℎ food source is. in the onlooker bees' stage, an artificial onlooker bee chooses its food source determined by the above observed probability value. thereafter, a food source for an onlooker bee is selected, a new region source is determined according to the eq. (36) and its fitness value is integrated. just as in the employed bees stage, a greedy selection is given. 3.2.3.4 scout bee stage the abandonment counter ��6]5di^*� of all employed bees are tested with a preset number of trials, called limit1. the employed bee, which cannot improve self-solution until the abandonment counter contacts to the limit1, becomes scout bee. then a new solution is calculated for the scout bee by using eq. (35) and the abandonment counter is reset. the scout bee, which a solution was produced for itself, becomes the employed bee. therefore, scout bees in abc prevent stagnation of employed bee population. 3.2.4 crossoved firefly -artificial bee colony (cfa-abc) algorithm the meta-heuristic methods are more powerful for the search of global solution for complicated problems and it is better than deterministic algorithm. though their disadvantage, e.g., the time of convergence which is due the high number of the population size and repetition, and in order to deal with this problem two metaheuristic methods are joined, the crossoved firefly and the artificial bee colony algorithm with a lesser symbol of bees and fireflies as possible. this paper introduce a hybrid design which has two search steps. the first step is a search by crossoved firefly algorithm (cfa) and second step is searching by artificial bee colony algorithm (abc) [22]. nizar hadi abbas al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 4560 (2016) 51 fig. 3: structure of the kinematic neural controller. fig. 4.the structure of multi-layer perceptron (mlp) neural networks. the summarization of the computation procedure of hybrid method is described by the pseudo code below[22]: step1: initial pop of fireflies xlp* , i1 = 1,2, …… , s. step 2: evaluate objective function f�xp*� for each firefly. step 3: set flash absorption coefficient γ , βl=,α1. step 4: flash intensity fp* at xlp* is calculated by f�xlp*�. step 5: while t < max iteration. step 6: calculate the value of alpha by eq. (32) step 7: for i1=1: s for all s fireflies. for j1=1: s for all s fireflies. step 8: if (fx* > fp*� movement all firefly i1 towards j1 (ddimension) by eq. (31) concording to the luminousness between i1 and j1 can be determined by eq. (30) step 9: else movement all fireflies by eq. (33) . step 10: end if. step 11: valuate the new fireflies and update flash intensities. step 12: end for j ,end for i1 step 13: order the fireflies and find the best. step 14: end while. nizar hadi abbas al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 4560 (2016) 52 the best solution found by cfa are regarded as initial point for abc. step 15: evaluate the fitness function for each employed bees by eq. (35). step 16: while (termination criterion not satisfied). employed bees stage step 17: for each employed bee. create new food source positions by eq. (36). use greedy selection mechanism. step 18: end for. calculate the probability plp* values for the solution xlp*x* by the eq. �37�. onlooker bees stage. step 19: for each onlooker bee. chooses a food source xlp*x* depending on create new food source positions by eq. (36). use greedy selection mechanism. step 20: end for. scout bee stage. if there is the employed bee becomes scout then change it with new random source solutions by eq.(34). 3.2.5 results of optimization algorithms the results of optimization algorithms are showing in the next section after appling on the benchmarks function for minimization, when the benchmarks are the test function. table 1, the optimization results. cfa-abc cfa fa bench function 603.734 743.1403 1.0086e+003 f1 936272 3.6879e+005 1.1321e+006 f2 2462.28 1.2057e+003 1.6745e+003 f3 8.7319e007 1.0803 1.1776 f4 0.0138406 8.85986 10.1603 f5 table 2, standard benchmark functions. function no. ¤\ℎjaj = ¥ �+̂� ^x* f1 �63j5¦a6%ℎ = ¥ �100��^0* − �+̂�+�2* ^x*+ ��^ − 1�+ � f2 ��3da4§45 = ¥ ��+̂ − 10 cos �2¨�^�� ^x*+ 10� f3 ©a4js�5z = ¥ � �+̂ 4000�� ^x*− « cos ¬�^√4® + 1� ^x* f4 �%zij� = 20 + j − 20 ∗ j k*� ∑ ��d �̄��°±.d − j*�∑ ²³´ �+µ�� ��̄�� f5 4. kinematic neural controller design based on hybrid cfa-abc algorithm this paper introduce a cfa-abc for searching the optimal controller parameters .the searching procedures of proposed method shown as below: 1. initial searching weights ($u=̂ ,¶tu= , yu*= , yt+= � of each firefly are created randomly with in the determined range. note that the dimension of search space consists of all the control parameters needed in the kinematic neural controller as shown in figure (2). 2. the objective function is calculated for each firefly by the mean square error function as equation [1]: (mse)= *+ ∑ ��e���· − ����·�+ + ��e���· −·�··x*����·�+ + ��e���· − ����·�+ … �38� 3. applied step3 to step 13 from the pseudo code of (cfa-abc) to find the best weight with minimizing trajectory tracking error. 4. the best weight are regarded as initial point for abc. 5. the objective function is calculated for each bee by the mean square error function as equation (38). nizar hadi abbas al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 4560 (2016) 53 6. applied step14 to step 19 from the pseudo code of (cfa-abc) to find the optimal weight. 7. if the iteration number arrive at maximum, then exit, else ,go to (2). 5. simulation results the aim of the simulations is to examine the effectiveness and performance of the proposed kinematic neural controller based on (cfa-abc) optimization algorithm to the wheeled mobile robot by using matlab programming environment. the resulting wheeled mobile robot trajectory tracking, get by the proposed kinematic neural controller is containing trajectory tracking, tracking error, and linear and angular velocity of mobile robot, linear velocity of right and left wheel and the mean square error. these simulation are performed with the parameters setting illustrated in table 4. table 3, simulation parameters setting. parameter setting the number of fireflies 20 the number of bees 20 the length of ni-robot 0.36 m the radius of ni-robot ra=0.05 the period time 0.5 sec iteration of cfa 100 iteration of abc 100 required linear velocity 0.1 m/sec required angular velocity 0.1 rad/sec case study1: the required circular trajectory, can be explained by the next equations: �e� � = cos & 10, �e� � = sin & 10, �e� � = 2̈ + 10 the wheeled mobile robot model starts from the initial pose (position/ orientation), ��= = [1.1,−0.5, \42 ] while the real initial pose (position/ orientation) of the mobile robot �e =[0.9,0.05,1.62], circular trajectory tracking simulation of the ni mobile robot is shown in fig. (1a). it's so clear that great tracking performance that achieved by the proposed controller based on optimization, because of eliminating the error with fast convergence. case study2: the required lemniscates trajectory, can be explained by the next equations: �e� � = 0.75 + 0.75 ∗ sin ¬2¨ 50 ® �e� � = sin ¬4¨ 50 ® �e� � = 2 d�52*� ∆�e� � k�∆�e� ��+ − �∆�e� ��+ + ∆�e� � the wheeled mobile robot model begins from the initial pose (position/ orientation), ��= = [0.7,−0.02, \42 ] while the real initial pose (position/ orientation) of the mobile robot �e =[0.79,0.12,1.21], lemniscates trajectory tracking simulation of the ni mobile robot is view in fig. (1b). the initial values of learning rate and weights are tuned such a way that it provides better performance. • the simulation results explained the effectualness of the suggested kinematic neural controller based on (cfa-abc) technique by displaying its ability to produce limited smooth values of the control velocities for right and left wheels outside sudden spikes .as a result showing in fig. (2a), fig. (2b). • fig. (3a), fig. (3b) indicate the convergence of the pose path and orientation errors for the robot model motion mse (ex,ey,eθ) equal (0.027,0.012,0.0031) for case study1 and mse(ex,ey,eθ) equal (±0.005,0.0072, -0.02) for case study2. • the performance index mse for pose path and orientation errors for the mobile robot model motion for 100 iterations are shown in fig. (4a) is (0.0063) and fig. (4b) is (0.0066). • fig. (5a) demonstrates the mean linear velocity (0.02 m/s) and the maximum peak of the angular velocity (0.005 rad/s) of the ni mobile robot> • fig. (5b) demonstrates the mean linear velocity (0.055 m/s) and the maximum peak of the angular velocity (±0.027rad/s) of the ni mobile robot. • the performance described in fig. 6a, fig.6b, fig. (7a), fig. (7b), fig. (8a) and fig. (8b) verify the effectiveness of the proposed control algorithm based on (cfa-abc) algorithm is nizar hadi abbas al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 4560 (2016) 54 clear by viewing the convergence of the pose error (position/orientation) for the wheeled mobile robot with small error. fig. (1a). actual trajectory of mobile robot and desired circular trajectory tracking. fig. (1b). actual trajectory of mobile robot and desired lemniscates trajectory tracking. fig. (2a). the right and left wheel velocity. fig. (3a). trajectory tracking error. fig. (4a). the performance index (mse). fig. (5a). the linear and angular velocity. -1.5 -1 -0.5 0 0.5 1 1.5 -1 -0.5 0 0.5 1 1.5 x-coordinate(meters) yco or di na te (m et er s) desired trajectory actual mobile robot trajectory 0 0.5 1 1.5 -1.5 -1 -0.5 0 0.5 1 1.5 x-coordinate(meters) yco or di na te (m et er s) desired trajectory actual robot trajectory 0 20 40 60 80 100 120 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 sampling time=0.5 sec w he el v el oc it y of r ig ht a nd l ef t ( m /s ec ) the velocity of the right wheel the velocity of the left wheel 20 40 60 80 100 120 -0.1 0 0.1 0.2 0.3 0.4 0.5 0.6 sampling time=0.5 sec e rr or ( m ) ex ey etheta 10 20 30 40 50 60 70 80 90 100 6.34 6.36 6.38 6.4 6.42 6.44 6.46 x 10 -3 number of iteration p er fo rm an ce i nd ex (m se ) mse 20 40 60 80 100 120 0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 sampling time=0.5 sec l in ea r v el oc it y (m /s ec ) a nd a ng ul ar v el oc it y (r ad /s ec ) the linear velocity the angular velocity nizar hadi abbas al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 4560 (2016) 55 fig. (6a). desired orientation and actual mobile robot orientation. fig. (7a). position tracking in xcoordinate. fig. (8a). position tracking in ycoordinate. fig. (2b): the right and left wheel velocity. fig. (3b). trajectory tracking error. fig. (4b): the performance index (mse). 20 40 60 80 100 120 1 2 3 4 5 6 7 8 9 sampling time=0.5 sec o ri en ta ti on ( ra d) desired orientation actual robot orientation 20 40 60 80 100 120 -1.5 -1 -0.5 0 0.5 1 1.5 sampling time=0.5 sec x -c oo rd in at e (m ) desired x-coordinate actual robot x-coordinate 20 40 60 80 100 120 -1.5 -1 -0.5 0 0.5 1 1.5 sampling time=0.5 sec y -c oo rd in at e (m ) desired y-coordinate actual robot y-coordinate 10 20 30 40 50 60 70 80 90 100 -0.1 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 sampling time=0.5 sec w he el v el oc it y of r ig ht a nd l ef t (m /s ec ) the velocity of the right wheel the velocity of the left wheel 10 20 30 40 50 60 70 80 90 -1.5 -1 -0.5 0 0.5 sampling time=0.5 sec e rr or ( m ) ex ey etheta 10 20 30 40 50 60 70 80 90 100 6.8342 6.8343 6.8343 6.8343 6.8343 6.8343 6.8343 6.8343 x 10 -3 number of iteration p er fo rm an ce i nd ex ( m se ) mse nizar hadi abbas al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 4560 (2016) 56 fig. (5b): the linear and angular velocity. fig. (6b). desired orientation and actual mobile robot orientation. fig. (7b): position tracking in xcoordinate. fig. (8b). position tracking in ycoordinate. 6. conclusion in this paper, an enhanced firefly algorithm called crossover firefly algorithm (cfa) and hybrid with artificial bee colony (abc) are proposed. these algorithms are utilized to enhance the optimization solution value by shortening the randomness step by step. the simulation results for finding the global optima of diverse test functions are used to verify the functioning of the suggested optimization algorithms. moreover, the research has presented an optimal kinematic neural controller based on (cfa-abc) algorithm for two-wheeled differential mobile robots to achieve both trajectory tracking and stabilization based on the kinematic model. it has been built and tested using matlab (r2013b) environment applied on national instrument mobile robot (ni mobile robot). the main result shows that the proposed control gets stability in the position errors and good follow of the trajectory tracking without perturbations, such that the mobile robot follows a desired path trajectory with minimize error. additionally, the simulation results show clearly the ability of reworking and robustness of the suggested kinematic neural controller that based on (cfa-abc) learning technique, which has wonderful position trajectory tracking achievement and it has the ability of producing smooth and acceptable linear and angular velocity. the suggested controller has explained the ability of tracking continuous gradients required trajectory and effectively reducing the tracking errors of the wheeled mobile robot model with mse of a circular trajectory is (0.0063) and 10 20 30 40 50 60 70 80 90 -0.04 -0.02 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 sampling time=0.5 sec l in ea r v el oc it y (m /s ec ) an d a ng ul ar v el oc it y (r ad /s ec ) the linear velocity the angular velocity 10 20 30 40 50 60 70 80 90 100 -5 -4 -3 -2 -1 0 1 2 3 sampling time=0.5 sec o ri en ta ti on ( ra d) desired orientation actual robot orientation 0 20 40 60 80 100 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 sampling time=0.5 sec x -c oo rd in at e (m ) desired x-coordinate actual robot x-coordinate 10 20 30 40 50 60 70 80 90 100 -1.5 -1 -0.5 0 0.5 1 1.5 sampling time=0.5 sec y -c oo rd in at e (m ) desired y-coordinate actual robot y-coordinate nizar hadi abbas al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 4560 (2016) 57 �¤» of the lemniscates trajectory is (0.0066) after 100 iterations, better then mse in [21]and[11]. list of symbols symbol definition alpha the flat crossover coefficient yr the weight between the bias and hidden (j). yzthe weight between the bias and output (k). c the mobile robot center (meter). �6]5di^*� the abandonment counter of the employed bee. d1 the dimensional vector of abc . ?jid�parameter to reduce the randomness. e the error vector. [ the flash intensity. [= the standard flash intensity. �41 the fitness value of the solutionr . �4d5j33 4 the fitness of each food source. fm1 a population of abc produce randomly. [� the intensity at the beginning. hntj the output of the hidden layer node j. iccm the instantaneous center of curvature mobile robot. 45\]d4 (exm(l),exm(l-1),…vl (l-1)). l measure of the running step. l1 the length between each wheel and the robot axis of symmetry in yguidance (m). m the number of input of neural network. m4 the number of input layer nodes. mr the number of hidden layer nodes. mzthe number of output layer nodes. pop number of individuals. � the radius of each wheel (rad). rr the distance between any two fireflies. a�5?the random number generator uniformly distributed in [0, 1]. v the translational velocity of the robot (meter/second). �i^*u* a new nominee solution of abc. $r4 the weight between input (i) and output (j). $ the linear left wheel speed (meter/second). $� the linear right wheel speed (meter/second). ¶zrthe weight between the hidden (j) and output (k). �==, �==, �==� the initial pose (position/orientation) of the robot. ��, �, �� the actual pose (position/orientation) of the robot. (�e , �e , �e� the desired pose (position/orientation) of the robot. �i^*u* solution produced from abc. �iu*v^� , �iu*v�� the lower boundary and upper boundary of the parameter j1. fm1 a population of abc produce randomly. [� the intensity at the beginning. hntj the output of the hidden layer node j. iccm the instantaneous center of curvature mobile robot. 45\]d4 (exm(l),exm(l-1),…vl (l-1)). l measure of the running step. l1 the length between each wheel and the robot axis of symmetry in yguidance(m). m the number of input of neural network. m4 the number of input layer nodes. mr the number of hidden layer nodes. }1 the randomization parameter. g�= the luminousness at rr=0. g� the luminousness of firefly. �� the angular left wheel speed (rad/second). nizar hadi abbas al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 4560 (2016) 58 ��� the angular right wheel speed (rad/second). e the fixed flash absorption coefficient. ∆ the interval between two sampling times. ω the rotational velocity of the robot (rad/second). ∅ a random real number in the interval of [−1, 1]. ŗ the rotation matrix. 7. references [1] g. artus, p. morin, and c. samson, tracking of an omnidirectional target with a nonholonomic mobile robot, in proc. ieee conf. adv. robot. (icar), 2003, pp. 1468– 1473. [2] k. seo, and j. s. lee, kinematic pathfollowing control of mobile robot under bounded angular velocity error, advanced robotics vol. 20, no. 1, pp. 1-23, 2006. [3] y. kanayama, y. kimura, f. miyazaki, and t. noguchi, a stable tracking control method for an autonomous mobile robot, in proc. ieee int. conf. robot. autom. cincinnati, oh, vol. 1, pp.384-389, 1990 . [4] o. mohareri, r. dhaouadi, and a. b. rad, indirect adaptive tracking control of a nonholonomic mobile robot via neural networks, neurocomputing, vol. 88, pp. 54 – 66, 2012. [5] i. kav, intelligent control schemes for nonlinear system, ph.d thesis, indian institute of technology, kanpur, india, 2008. [6] g. wang and l. guo, a novel hybrid bat algorithm with harmony search for global numerical optimization, journal of applied mathematics, vol. 2013, 21 pages, 2013. [7] x. li and m. yin, an opposition-based differential evolution algorithm for permutation flow shop scheduling based on diversity measure, advances in engineering software, vol. 55, pp. 10–31, 2013. [8] x.-s. yang, z. cui, r. xiao, a. h. gandomi, and m. karamanoglu, swarm intelligence and bio-inspired computation , elsevier, waltham, mass, usa, 2013. [9] a. al-araji, design of a cognitive neural predictive controller for mobile robot,brunel university, united kingdom, 2012. [10] j. ye, adaptive control of nonlinear pidbased analogue neural network for a nonholonomic mobile robot , neurocompting, vol. 71, pp. 1561-1565, 2008. [11] a. al-araji, a comparative study of various intelligent algorithms based nonlinear pid neural trajectory tracking controller for the differential wheeled mobile robot model, journal of engineering, vol. 20 ,may 2014. [12] z. yousif, j. hedley, and r. bicker, design of an adaptive neural kinematic controller for a national instrument mobile robot system, ieee international conference on control system, computing and engineering, 23 25 nov. 2012, penang, malaysia. [13] r. fierro, and f. l. lewis, control of a nonholonomic mobile robot using neural networks, ieee trans. neural networks, pp. 589-600, 1998. [14] f. l. lewis, k. liu, and a. yesildirek, neural net robot controller with guaranteed tracking performance , ieee transaction on neural networks, vol. 6, no. 3, pp. 703-715, 1995. [15] x. s. yang, firefly algorithms for multimodal optimization , in watanabe, o.,zeug-mann,t.(eds.) saga 2009. lncs, vol.5792, pp.169-178. springer, heidelberg, 2009. [16] a. l. bolaji, a. t. khader, m. a. al-betar, and m. a. awadallah, artificial bee colony algorithm, its variants and applications: a survey, journal of theoretical and applied information technology, vol. 47, no.2, pp. 434-459, 2013. [17] m. h. saffari, and m. j. mahjoob, bee colony algorithm for real-time optimal path planning of mobile robots, fifth international conference on soft computing, computing with words and perceptions in system analysis, decision and control (icsccw), eng., univ. of tehran, tehran, iran, 2-4 sept. 2009. [18] w. xiang, s. ma and m. an, an improved artificial bee colony algorithm with multiple search operators, journal of computational information systems, pp. 3129–3139, august 2013. [19] d. karaboga and b. akay, a modified artificial bee colony algorithm for realparameter optimization, swarm intelligence nizar hadi abbas al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 4560 (2016) 59 and its applications, elsevier, vol. 192, pp.120-142, june 2010. [20] d. karaboga, an idea based on honey bee swarm for numerical optimization, technical report, erciyes university, engineering faculty, computer engineering department, pp. 1-10, 2005. [21] a. almeshal , k. goher , m.r. alenezi , a. almazeed , j. almatawah and m. moaz, bfa optimized intelligent controller for path following unicycle robot over irregular terrains, international journal of current engineering and technology, vol.5, no.2 (april 2015). [22] m. younes, r. l. kherfane and f. khodja , a hybrid approach for economic power dispatch, djillali liabes university, vol. 8, july 2013. �� 1، ا���د����12 ا���ارز � ا������� ا���� ��ار ھ�دي ���س � ،2016( 4560( 60 )-��2 و/�ة ��1*ة /*.�� �-��� �''�, +�ر ا�*و%�)�ت ا��'�&�� %��$ت ��" أ��س 3� ا���+7 ا����7 %�7 �4ارز �� ا��*��ت ا���5�6 و�4ارز �� ���4 ا�� **%+�� ج��� ��8* ��ار ھ�دي ���س �� ا��������� **،*���/ "! ا�����اد'�&%� /$#�� ا���)� drnizaralmsaodi@gmail.com **+ا.��-�و �:ا��0/ eng.basmaj@gmail.com :ا��0/� ا.��-�و+** * ا��$ � &!�:� e�'f-� *08> *$�g *#&��9 ا>�* ا�7-�6ك ا�07�c#> * أ��س �--0@ &!�ر <=#� ا>+!�ن ا&!�:� �7�789، ا�560 /4�م ھ1ا ا�(�/� &l ا�7!�:� ھ* o/�49 ا�!�<� ا�n� ��4�46+!�ن ا>�* ا"�ب &� ، national instrumentا�87��j k0" l& @$� ا��و�fت ا�f767ل � ��f#:7ا�!�<� ا� l& نf�/�p8ا� cا"�ب ا� �:qل ا��4�ار &%& k%= .l�-40ط l& نf�-/ 560ھ1ا ا� *s ھ* : ا�7!�:� ا�47-�ح cا�:�40 ا.و� �د ا�:�40ت �--0@ ا�7!�ر ا�f#:7ب و ا�:�40 ا��x+�� ھ* ط�40 ا�fqارز&�� ا.&x#�� وا�-* fv k7w9ارز&�� ھ=��� &6!%-& ��0 <��08j م�y+ �� �م .وھ* &�fv l& �+fارز&�� ا���<�q-!9و k6�ا� ��#v ��&ارزfvو �z�[7ت ا�kx&<ل �#7!�ر اf\f7!�:� وا�#� �" k]s[ل . /=�د أv l& �ام ��+�&_ ، +-��_ ا��67$�ةq-�4�ار v:� و�`"k "��7 وa79 ا��67$�ة �`& cل ا�f\f��� �7�9ء�p$ ��#x&<ارز&�� اfvا�7!�:� ا�47-�ح و a0cا l& l�>f+ c#> ��4�0:9 9ا�7!�رات ا�9�7[ب و)*-�p+<ا��ي وا� ).ا� (microsoft word 93-106\335\321\307\323 \346\343\321\312\326\354) al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 14, no.2, june, (2018) p.p. 93106 creeping gait analysis and simulation of a quadruped robot firas a. raheem* murtadha khudhair flayyih** *,** department of control and system engineering/ university of technology *email: 60124@uotechnology.edu.iq **email: cse.60354@uotechnology.edu.iq (received 22 may 2017; accepted 5 december 2017) https://doi.org/10.22153/kej.2018.12.004 abstract a quadruped (four-legged) robot locomotion has the potential ability for using in different applications such as walking over soft and rough terrains and to grantee the mobility and flexibility. in general, quadruped robots have three main periodic gaits: creeping gait, running gait and galloping gait. the main problem of the quadruped robot during walking is the needing to be statically stable for slow gaits such as creeping gait. the statically stable walking as a condition depends on the stability margins that calculated particularly for this gait. in this paper, the creeping gait sequence analysis of each leg step during the swing and fixed phases has been carried out. the calculation of the minimum stability margins depends upon the forward and inverse kinematic models for each 3-dof leg and depends on vertical geometrical projection during walking. simulation and results verify the stability insurance after calculation the minimum margins which indicate clearly the robot cog (center of gravity) inside the supporting polygon resulted from the leg-tips. keywords: quadruped robot creeping gait, stability margins, quadruped robot simulation. 1. introduction leg-based walking systems utilization has turned out to be very familiar with the robotics field. these systems present better adaptability over wheeled systems, particularly when dealing with irregular territories [1]. the ability of legged robots in dealing with rough territories and obstacles which also have the planning technique of the standard walking gaits for a quadruped robot [2, 3]. among legged robots, quadrupeds have the preferred of having a less complex structure while fulfilling the requirements for usage of a statically stable gait during walking, resulted from the stable support polygons. a lot of researches about the quadruped locomotion frequently have its origins in the investigation of natural biological walking gaits. these studies have prompted to the improvement of both statically stable walking gait and dynamic running gaits for legged robots [4]. the main point is the need to design and implement a robust and statically stable gait during the quadruped robot walking. the property of their gaits would be repeating the ability of step sequence and stability over irregular territories [5]. step sequences for quadrupeds, and the criteria for stability verification on an inclined terrain, as well as the talking about moving between varieties in gait and omnidirectional statically stable walking [6]. stability criteria have some elements such as cog (centre of gravity), support polygon and stability margin which is also talked about the gait transitions performed by the creeping gaits [7, 8]. the generation and the sequence of such leg motion in the quadruped robot is called gait [9]. there are many motions that quadruped robots doing, such as stair climbing with many performances [17], flying trotting [19], jumping [20], and walking/trotting over obstacles [18]. generally, the gait of quadruped robots can be separated for two groups: the first one is the statically stable gait and the second one is the firas a. raheem al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 93106 (2018) 94 dynamic running gaits, depending on the gait type [10]. quadruped body must be stable and have the ability during any transition gait for moving from one position to another. the statically stable gait is simpler and slower contrasted with dynamic gaits. it indicates that the cog projection of quadruped robot is on the ground at instance time is inside support polygon during the walking. among these properties, the quadruped robot meets the necessity of both force and moment adjustment during the walking gait and here the quadruped robot is said to be statically stable. dynamic gaits such as the trotting gait [11] aim to the reality that if the cog projection of the quadruped robot on the ground is not inside the support polygon framed by the leg tips. in this case, the quadruped robot is in the unbalanced period and has a tendency of dumping. then the quadruped robot in case of the dynamic running gaits needs to satisfy the dynamically stable requirement rather than static stability analysis. most of the quadruped robots can be considered as statically stable, when there are three legs at least should be stayed in contact with the ground at the same instant time while another leg is swinging in the air. the most biological statically stable gait that matches the animals or insects is the creeping gait. in this paper, the problem of static stability analysis is achieved. this is sufficient for ensuring safety walking. during the movement of the quadruped robot, the motion will be stable if and only if the body center of gravity cog is either inside the supporting triangle in case of one leg in a transition phase or inside the supporting polygon in case all legs are on the ground. at the time period of the quadruped robot is walking the problem is how to produce and control sequence of putting and lifting all the legs extend at any time moment. the quadruped robot walks with stable steps if the stability margins have positive values, another case the robot will be unstable and the walking gait will fail. 2. quadruped robot description to concentrate on the general guidelines of quadruped robot motion gaits, though, different models with some acknowledgment attributes is embraced. these attributes have three criteria [13] 1. the standard quadruped walking at constant speeds, at steady state movement, over an even supporting surface. in this case, the legs of the quadruped robot are repeated periodically during the locomotion. 2. the standard quadruped robots are symmetrical in both longitudinal and lateral directions. this property leads to the facts that the design is adapted to have a similar structure for every leg with less the mechanical complexity of the system and then less in cost . 3. in case of a regular shape quadruped robot, cog located at the robot geometrical center of the quadruped robot body, which is known as cog the center of gravity. the quadruped robot is shown in figure (1) demonstrates the typical model of a quadruped robot which represented the above three criteria. in this research, the motion task assumption includes that the quadruped robot walks towards the x-axis only. this means that there is no change in the y-axis stride. so the vertical projection of the stride for all legs is a line. these stride lines are situated in the longitudinal direction to fulfill the condition of forwarding walk. fig. 1. quadruped robot (top view) illustrate the length (2b) and the width (2c) and the cog point from figure (1), the distance for all legs from the closest point of the stride line to the cog projection is (a), the distance for all legs from the farthest point of the stride line to the cog projection is (b)and (c) is the distance between two front stride line or two back stride line. the definition of stride line for every leg in x-axis is [13] stride line (λ) = b – a …(1) when the quadruped robot body is moved the cog is moved, correspondingly followed by the firas a. raheem al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 93106 (2018) 95 four legs moving. according to the gait sequence of quadruped robot creeping gait, there is no necessity to move the robot body and legs at the same time [14]. the forward walking is towards the x-axis. in the first origin support pattern, the positions of the four legs at (x1, c) (x2,-c) (x3, c) (x4,-c), and the length of stride is λ. by this manner, the positions of every leg after one step movement are located at (x1+ λ, c) (x2+ λ, -c) (x3+ λ, c) (x4+ λ,-c). these locations should be matching the stride constraint as follows: � � �� � � � � �� � � �� � � � �� �� � � � �� � � �� � λ � � � � �� � λ � � �� � � � λ � �� �� � � � λ � �� along these considerations, the largest stride of the reachable area for a quadruped robot can be calculated from equation (1). most of the quadruped robots have the value of length equals to 2 b and the value of width equals to 2 c. henceforth, the ratio between the length and width is equal to c/b. in this paper, each leg contains three joints 3-dof called (coxa-joint, femur-joint, and tibiajoint). so the total number of dofs is equal to 12. the overall the quadruped robot is showing in figure (2). where in figure (2-a) shows the main part in the quadruped robot is represent a mimic of the natural anatomy of legged animals. from figure (2-a), leg1 is the right front (rf) side and leg3 is the right rear (rr) side and leg2 is the left front (lf) side and leg4 is the left rear (lr) side. in this figure, it is illustrated and guaranteed to be inside the supporting polygon. the forward direction of motion of the quadruped robot, in case of the forward direction of motion, is set to be with the x-axis direction and the lateral motion of the quadruped robot will be in y-axis. the quadruped body has a symmetrical dimension in x and y axes. this gave the robot better stability during the walking and making it statically stable. in figure (2-b) shows each leg has three links and joints (coxa, femur, and tibia). (a) (b) fig. 2. quadruped robot simulation using matlab (a) quadruped robot with four legs labeling (b) showing the three joints (coxa, femur, tibia) in each leg. to grantee that the quadruped robot is at stable situation during its movement, the position of each leg plays a very important rule of the stability calculations. in order to ensure the static stability condition of the quadruped robot, the forward kinematics and inverse kinematics is needed priory before analysis. 3. creeping gait analysis and sequence description the quadruped robot gaits can be classified into three types of main gaits depending also on the value of the duty factor ( �), where i=1,..4, like: crawl gait, running gait, and the galloping gait. the duty factor ( �) is the ratio between the time period of one leg spend in the air to the time period spend on the ground, according to the creeping gait sequence, creeping gait has duty factor equal to 0.75. the running gait has duty factor ranging between 0.5-0.75, and the galloping firas a. raheem al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 93106 (2018) 96 gait has a duty factor less than 0.5. these gaits that are utilized by quadruped animals have regularly been given names, which generally known as creeping gait, trotting gait and bounding gait [١6]. some of these gaits are utilized by some mammals. for a very slow walking, animals such as elephants are using the creeping gait. the advantage of this gait, that it can be generally statically stable movement and it can be used at the range of low-speed motions. the creeping gait needs at least three legs on the ground at the translation phase of the other leg in the air. this condition is important for achieve a statically stable gait. the creeping gait used the mechanism that the back leg is touching-down the ground followed by the front leg in the same side leaving the ground. after the front leg is touching-down the ground, the back leg in the other side of the body will begin to leave the ground, and so on, this sequence is repeated continuously during the locomotion of the quadruped robot. there are six types of legs sequences for quadruped robot. in this paper, the leg swinging sequence is (rr→rf→ lr→lf) where (r: right, l: left, r: rear, f: front). where rr is leg4, rf is leg2, lr is leg3, and lf is leg1. the main feature of this specific sequence is to have a safe walking that ensures the body robot of moving forward at the instance time [12]. there are two cartesian coordinate reference frames in the quadruped robot locomotion: the first one is the ground frame, the second one is the coxa joint frame related to the robot body. in these coordinate frames, the front side of the body is set towards the x-axis, while the body left side direction is set towards the y-axis. in this way, these two frames are important for the computations that ensure the cog location is inside the robot body projection during leg placing and lifting. [13] 4. kinematics modeling of a quadruped robot 4.1 forward kinematics depends on the leg design, a quadruped robot relies on the configuration of each leg. since all parts of walking are represented by the physical constraints of the leg. each leg has three-revolute joints named in the kinematical chain (r1, r2, r3). these joints have been chosen for every leg mechanism. the basic idea is to model the robot leg structure as the biological leg structure for animals or insects. the forward kinematics is applied to drive the geometrical model for every leg related to the center of the robot body, and then find the position and orientation of the endtip (xi, yi, zi) where i=1,2,3, and 4, for each leg, the leg structure appeared in figure (3) fig. 3. coordinate frames for one leg of a quadruped robot. [9] the d-h (denavit-hartenberg) parameters of the leg are shown in table (1). the leg's frame of this robot begins with the link zero which is the point on the robot body. the leg is jointed as link one is the coxa link, link two is the femur link and link three is the tibia link. legs are set to be symmetrically around the coordinate axis in the direction of movement. in our case, the direction of motion is the x-axis. the general frame for the transformation matrix from a link i to a link (i-1) utilizing the d-h parameters is given in equation (2.1) [9]: the definition of the transformation matrix is a multiple series of transformation along: 1. translate d� along ���� axis. 2. rotate �� about ���� axis. 3. translate �� along ���� axis. 4. rotate �� about ���� axis. so, for one link and joint the translations and rotations are illustrated in the transformation matrix as [21]: ����� = ������ ����������� ���������� ������������ ���������� ����������� �������00 �����0 ����� ��0 1 …(2) the link parameter table of one leg in the quadruped robot is firas a. raheem al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 93106 (2018) 97 table 1, the denavit-hartenberg parameters table for one leg in our quadruped robot link no. link name !" (deg) #" (cm) $" (cm) %" (deg) 1 coxa 90 �� �� �� 2 femur 180 �� 0 �� 3 tibia 0 � 0 � where �� = (9 cm), ��=2.5 cm ��= 5 cm, and � = 9 cm. �� is the distance from coxa joint to the ground. �� are the lengths of the leg links. now, obtaining the overall transformation matrixes by making a product of three transformation matrixes as the following: �&'()*)+, = �&'()-,./0 ∗ �-,./02�*�) …(3) from equation (2), the transformation matrixes for one quadruped’s leg are describing as below: ��3 = ��� 0 �� ������ 0 ��� ����00 10 0 ��0 1 …(4) ��� = ��� �� 0 ������ ��� 0 ����00 00 �1 0 0 1 ...(5) � � = �� �� 0 � � � � 0 � � 00 00 1 0 0 1 …(6) by multiplication the equations (4) and (5) 4��3 ∗���5 yields: ��� 0 �� ������ 0 ��� ����00 10 0 ��0 1 ��� �� 0 ������ ��� 0 ����00 00 �1 0 0 1 = ����� ���� ��� ��4����6��5���� ���� �� ��4����6��5��0 ���0 0 ���� � ��0 1 …(7) in the same method and by multiplication equations (7) by (6) 4��3 ∗ ���5 ∗ � � yielding equation (8): ���4��� 5 ����� ��� � ��4��� 5 � ��4����6��5��4��� 5 ��4��� 5 �� � ��4��� 5 � ��4����6��5��� 0 �4��� 50 0 � 4��� 5 � �2�2 � ��0 1 …(8) where: �� = ����� and �� = ����� , for i=1,2, and 3. 4��� 5= cos 4�� � � 5 4��� 5= sin 4�� � � 5 from the figure (3) and by using the equation (8), the coordinate position of each leg-tip can be calculated as the following: �� = �����4� 4������ 5 � 4�������6��55 (9) =� = �����4� 4������ 5 � 4�������6��55 (10) �� = � 4������ 5 � ������� � �� (11) where: (��,=�,��) is the coordinates of the leg-tip, i=1…4. 4.2 inverse kinematics the inverse kinematics method formulated the joint angles from a given position and orientation of the legs tip. these position and orientation are achieved from the forward kinematics. the objective is to find the leg three joint angles ��,�� and � , relating to the required of the leg tip position [15] as shown in figure (4). fig. 4. front view showing one leg of the quadruped and its links (coxa, femur, tibia) [15] to find the inverse kinematics in each leg joint, the method simplifies this problem from 3d problem view into two 2d problem view, after that, using the geometrical analysis to solve and find the solution for (��,�� and � ), as showing in figure (5) fig. 5. quadruped top view showing %> from figure above, �� can be calculated, as the following: firas a. raheem al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 93106 (2018) 98 (? = tan 4��5 thus, �� = b����4(?5 …(12) to find the other two angels which are �� and � . these angles are in the same (y-z) plane. to find ��, divide this angle into ��and �� to simplify the problem. to find �� firstly working out on the distance l to get the angle �� as showing in the following figure (6). fig. 6. quadruped robot one leg side view showing links (coxa, femur, tibia) and %c and %d [15] from the figure above calculate the followings: e = f�'--+,2� � 4e� � �5�g …(13) where c is the coxa link length, and: �� = �����4hijjklmn 5 …(14) from the cosine rules, �� and � angles can be calculated. from figure (6) shown above the three sides of a triangle are (femur, tibia, and l). to calculate �� : �� = o� � e� � 42 ∗ o ∗ e5cos 4��5 thus: �� = ����� pqg6ng�rg�∗q∗n s …(15) where: f is the length of femur link. t is the length of tibia link. although, ��is equal to: �� = �� � �� �� = ����� phijjklmn s � ����� pqg6ng�rg�∗q∗n s …(16) finally, � is calculated as: � = ����� pqg6rg�ng�∗q∗r s …(17) 5. stability analysis for quadruped robot creeping gait 5.1 static stability criterion with a specific goal for the quadruped robot to walk with statically stable movements, the cog projection on the ground should be inside the supporting polygon framed by the leg tips. this condition is considered as the main criteria for the statically stable walking. when this condition is completely satisfied, the quadruped robot won't overturn because of the gravity. furthermore, this analysis can be made for the legs gait sequence as discussed to be (leg4→leg2→leg3→leg1). during the swing period of leg4, the area of support triangle is framed by the tips of the supporting legs (leg1, leg2, leg3), and it has a symbolic as tr1. in the swing period of the leg2, the support triangle is shaped by the tips of the supporting legs (leg1, leg3, leg4). and this triangle has a symbolic as tr2. at this moment the intersection of the tr1 and tr2 resulted in another triangle named as dst1. in which the cog projection must be inside this triangle to ensure the static stability when leg4 and leg2 are in swinging phase. by the same way, the edges of supporting triangles tr3 and tr4 resulted during the period of swing leg3 and leg1, respectively. the intersection of the tr3 and tr4 resulting another triangle named as dst2. by the same condition that the cog must be inside the triangle dst2 triangle when leg3 and leg1 are in swinging phase. many series of dsts (double supporting triangles) will be shaped during the movement of the quadruped robot, thus, to ensure the statically stable condition the planned trajectory of the cog projection must be planned along the dst's progression sequence: dst1→dst2→dst3→dst4.... …(18) this grantee that the locomotion of the quadruped robot is statically stable [10]. the dst sequence of the quadruped robot motion is illustrated in figure (7). fig. 7. series of double support triangles on the ground frame [10]. firas a. raheem al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 93106 (2018) 99 the main advantage of making the walking locomotion of the quadruped periodically repeated is to achieve a constant velocity which leads to making the acceleration on the quadruped body is equal to zero, which reduces the disturbances on the swinging legs. 5.2 stability margin analysis in case of quadruped robot creeping gait walking, and according to static stability condition, the stability margins are utilized the shortest distance between the cog projection of the quadruped robot to the boundary limits of the supporting pattern [13]. the following figures explaining the mathematical model of a quadruped robot with the analysis of stability margins where the calculations of these stability margins as follows (a) (b) fig. 8. quadruped robot when leg4 is swinging (a) quadruped robot (b) quadruped support triangle the first case, shown in figure (8-a) when the quadruped robot leg4 swing in the air and legs (1, 2, and 3) on the ground. the supporting area will have three triangles, each triangle has a defined area (area1, area2, area3) and the minimum distance from one of the supporting lines (l1, l2, l3) to the perpendicular cog projection on the ground which is denoted as (t1, t2, t3). then the analysis of the stability margins at this period is showing in figure (8-b) as: tuv�� = �� w 1 1 1�&'x �� � =&'x =� = y where (�&'x , =&'x) is the coordinate of the center of gravity of the quadruped robot on the ground. (�� , =�) is the coordinate of leg1 position. (� , = ) is the coordinate of leg3 position. so, by expanding and simplify this matrix tuv�� can be calculated as the following: tuv�� = �� [\�� � �&'x]\= � =&'x] � \� � �&'x]\=� � =&'x]^ e� = _4�� � � 5� � 4=� � = 5� �� = 2 ∗ 4`0,)ana 5 ...(19) by the same way, tuv�� and tuv� can be calculated: tuv�� = �� [\�� � �&'x]\=� � =&'x] �\�� � �&'x]\=� � =&'x]^ e� = _4�� � ��5� � 4=� � =�5� �� = 2 ∗ 4`0,)gng 5 ...(20) tuv� = �� [\�� � �&'x]\= � =&'x] � \� � �&'x]\=� � =&'x] ̂ e� = _4�� � � 5� � 4=� � = 5� � = 2 ∗ 4`0,)bnb 5 …(21) finally, the first stability margin �c� is the minimum of these three margins: �c� = c�� 4��, ��, � 5 …(22) according to the quadruped robot creeping gait sequence, the robot swinging leg 2 while the other legs (leg1, leg3, and leg4) are on the ground, �c� can be found as the following (a) firas a. raheem al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 93106 (2018) 100 (b) fig. 9. quadruped robot when leg2 is swinging (a) quadruped robot 3d view (b) quadruped support triangle. the second case, showing in figure (9-a) when the leg2 is swinging in the air and the other legs (1, 3, and 4) will be on the ground. then the analysis of the stability margins at this period is showing in figure (9-b) as: tuv�� = �� [\�� � �&'x]\= � =&'x] � \ � � �&'x]\=� � =&'x]^ e� = _4�� � � 5� � 4=� � = 5� �� = 2 ∗ 4`0,)ana 5 …(23) by the same way, tuv�� and tuv� can be calculated: tuv�� = �� [\�� � �&'x]\= � =&'x] � \� � �&'x]\=� � =&'x]^ e� = _4�� � � 5� � 4=� � = 5� �� = 2 ∗ 4`0,)gng 5 …(24) tuv� = �� [\� � �&'x]\= � =&'x] � \� � �&'x]\= � =&'x]^ e� = _4� � � 5� � 4= � = 5� � = 2 ∗ 4`0,)bnb 5 …(25) finally, the second stability margin �c� is the minimum of these three margins: �c� = min 4��, �� , � 5 …(26) according to the quadruped robot creeping gait sequence, the robot swinging leg 3 and the other legs (leg1, leg2, and leg4) are on the ground, the �c can be found as the following (a) (b) fig. 10. quadruped robot when leg3 is swinging (a) quadruped robot 3d view (b) quadruped support triangle. the third case, showing in figure (10-a) when the leg3 is swinging in the air and the other legs (1, 2, and 4) will be on the ground. then the analysis of the stability margins at this period is showing in figure (10-b) as: area� = �� h4x� � xjkl 54y� � yjkl 5 � 4x� � xjkl 54y� � yjkl 5n l� = _4x� � x�5� � 4y� � y�5� t� = 2 ∗ 4qrstaua 5 …(27) by the same way, tuv�� and tuv� can be calculated: area� = �� h4x� � xjkl 54y � yjkl 5 � 4x � xjkl 54y� � yjkl 5n l� = _4x� � x 5� � 4y� � y 5� t� = 2 ∗ 4qrstgug 5 …(28) area = �� h4x� � xjkl 54y � yjkl 5 � 4x � xjkl 54y� � yjkl 5n l = _4x� � x 5� � 4y� � y 5� t = 2 ∗ 4qrstbub 5 …(29) firas a. raheem al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 93106 (2018) 101 finally, the third stability margin �c is the minimum of these three margins: �c = min 4��, �� , � 5 …(30) according to the quadruped robot creeping gait sequence, the robot swinging leg 1 and the other legs (leg2, leg3, and leg4) are on the ground, the �c can be found as the following (a) (b) fig. 11. quadruped robot when leg3 is swinging (a) quadruped robot 3d view (b) quadruped support triangle. the fourth case, showing in figure (11-a) when the leg1 is swinging in the air and the other legs (2, 3, and 4) are on the ground. then the analysis of the stability margins at this period is showing in figure (11-b) as: area� = �� h4x� � xjkl 54y � yjkl 5 � 4x � xjkl 54y� � yjkl 5n l� = _4x� � x 5� � 4y� � y 5� t� = 2 ∗ 4qrstaua 5 …(31) by the same way, tuv�� and tuv� can be calculated: area� = �� h4x� � xjkl 54y � yjkl 5 � 4x � xjkl 54y� � yjkl 5n l� = _4x� � x 5� � 4y� � y 5� t� = 2 ∗ 4qrstgug 5 …(32) area = �� h4x � xjkl 54y � yjkl 5 � 4x � xjkl 54y � yjkl 5n l = _4x � x 5� � 4y � y 5� t = 2 ∗ 4qrstbub 5 …(33) finally, the fourth stability margin �c is the minimum of these three margins: �c = min 4��, �� , � 5 … (34) 6. simulation and results this section is showing the simulation results of the analyzed stability margins which are necessary for the quadruped robot walking stability. according to the robot legs sequence, the results are achieved as the following (a) (b) fig. 12. showing (a) leg 4 in swinging phase (b) the stability margin vw>(cm) when leg4 is swing. (a) 50 40 x 30 20 10 0 0 10 20 y 30 40 leg 4 swing support triangle firas a. raheem al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 93106 (2018) 102 (b) fig. 13. showing (a) leg 2 in swinging phase. (b) the stability margin vwc(cm) when leg2 is swing. (a) (b) fig. 14. showing (a) leg 3 in swinging phase. (b) the stability margin vwd(cm) when leg3 is swing. (a) (b) fig. 15. showing (a) leg 1 in swinging phase. (b) the stability margin vwx(cm) when leg1 is swing. from figures shown above, it can be seen that all stability margins (sm�, sm�, sm , and sm ) have positive values. these values are sufficient to satisfy a stable walking for the quadruped robot creeping gait as assumed in this paper. the results of the stable creeping gait sequence for all legs have been converted into joint angles (��,��,� ) for each leg by using inverse kinematics analysis. so, the results contain the changing of each leg three angles and the change of distance of each leg-tip along x-axis direction and z-axis direction during the creeping gait walking of quadruped robot. the following figures (12-15) illustrate the quadruped robot configurations and results. (a) (b) fig. 16. when leg 4 is swinging. (a) leg 4 moved one step along x-axis. (b) leg 4 moved one step along z-axis. s m 2 ( c m ) 0 50 100 150 200 250 300 350 1 2 3 4 5 6 iteration s m 3 ( c m ) sm3 firas a. raheem al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 93106 (2018) 103 (a) (b) fig. 17. when leg 2 is swinging. (a) leg 2 moved one step along x-axis. (b) leg 2 moved one step along z-axis. (a) (b) fig. 18: when leg 3 is swinging. (a) leg 3 moved one step along x-axis. (b) leg 3 moved one step along z-axis. (a) (b) fig. 19. when leg 1 is swinging. (a) leg 1 moved one step along x-axis. (b) leg 1 moved one step along z-axis. from above figures it can be seen the following: 1. in figure (16): leg4 tip is swinging and moving from (-5 cm) to (-3.5 cm) along x-axis and (1.5 cm) along z-axis. 2. in figure (17): leg2 swinging and moving from (5 cm) to (7.4 cm) along x-axis, also the height of the lifting tip is (1.5 cm) along z-axis. 3. in figure (18): leg3 swinging and moving from (-5 cm) to (-2 cm) along x-axis, also the height of the lifting tip is (1.5 cm) along z-axis. 4. in figure (19): leg1 swinging and moving from (5 cm) to (8.5 cm) along x-axis, also the height of the lifting tip is (1.5 cm) along z-axis. as discussed in this paper, the quadruped walking along x-axis only while the y-axis is fixed, there is no changing in the y-axis during the walking of the quadruped robot. figure (20) showing this case. firas a. raheem al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 93106 (2018) 104 fig. 20. showing the changing of the leg tips along y-axis during the quadruped walking. during the creeping gait sequence, the quadruped robot leg angles are changing. these angles are (��,�� and� ) of each leg. this changing is showing in figure (21) (a) (b) (c) fig. 21. changing of angles (a) coxa-angle (b) femur-angle (c) tibia-angle from figure (21) shown above it can be seen the following: 1. figure (21-a) is the changing of leg1 angle��. this angle is varying between (15 degree) to (-15 degree). 2. figure (21-b) is the changing of leg1 angle��. this angle is varying between (30 degree) to (65 degree). 3. figure (21-c) is the changing of leg1 angle� . this angle is varying between (120 degree) to (140 degree). 7. conclusion the main focus of this paper is how to analyze the quadruped robot creeping gait walking and then to derive, verify and prove that the robot is statically stable during walking. in order to satisfy the goal of this work, first, the full forward and inverse kinematics model has been derived and used for walking steps stability validation. also, the interaction between creeping gait sequence made for this robot and the geometric modeling of robot legs-tip has been fully derived for finding all the static stability margins during walking. the results clearly prove that the stability margins have the positive values which guarantee to keep robot cog inside the supporting triangle during the swing phase of one leg while other legs are on the ground. furthermore, a future work development is needed to analyze and enhance the quadruped robot walking on the hard and rough terrain. notation cog center of gravity �&'x center of gravity in x-axis =&'x center of gravity in y-axis x1 leg1 tip in x-axis x2 leg2 tip in x-axis x3 leg3 tip in x-axis x4 leg4 tip in x-axis y1 leg1 tip in y-axis y2 leg2 tip in y-axis y3 leg3 tip in y-axis y4 leg4 tip in y-axis ��, ��, � distance from stability margins to the cog greek letter z stride line firas a. raheem al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 93106 (2018) 105 8. references [1] kumar, t. komal, r. kumar, s. mogily, d. goel, n. pareekutty, s. v. shah, and k. madhava krishna. 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[21] yang, chenguang, et al. advanced technologies in modern robotic applications. springer singapore, 2016. )2018( 93-106، صفحة 2د، العد14دجلة الخوارزمي الهندسية المجلمفراس عبد الرزاق رحيم 106 تحليل و محاكاة روبوت رباعي االرجل في حالة المشي **مرتضى خضير فليح *فراس عبد الرزاق رحيم الجامعة التكنلوجية /هندسة السيطرة والنظمقسم *,** uotechnology.edu.iq60124@البريد االلكتروني:* .uotechnology.edu.iq60354cse@البريد االلكتروني:** الخالصة على قدرته فضال عنعلى االرض المسطحة واالنتقال المشيروبوت رباعي االرجل له القابلية على القيام بمهمات عديدة منها ربوت هوالكوادروبيد على محاكاة الحيوانات او الحشرات رباعية االرجل من خالل تقليد الحركات التي تقوم بها هذه الحيوانات. إن المشي على االرض الوعرة. يقوم هذا الروبت القفز. ان حركة المشي التي تم تنفيذها في هذه الورقة هي والركض معالحركات التي يستخدمها هذا الروبوت في االنتقال هي: المشي والركض أشهرمن واحدة بعد االخرى خالل مدة زمنية معينة وبعد وصول الرجل الى المكان المناسب تبدأ رجل اخرى بالحركة. يستخدم هذا االيقاع في عبارة عن تحريك رجل االرجل سوفرفع احدى خالل عمليةانتقال الرجل المرفوعة. مدةصقة على االرض لتحقيق االستقرارية خالل لتم أرجلالحركة لكي نضمن بقاء ثالثة خالل هذه الحركات لذلك اثلث ناتج من اسقاط نقاط تثبيت بقية االرجل الثالث مع سنتر الروبوت على االرض.ان مهمة هذا الروبوت هو البقاء مستقريتكون م ) في هذه الورقة ايضا تم تحليل حركة الروبوت بالنسبة للمشي stability marginsيحتاج الى تحليل االستقرارية عن طريق حساب الـ ( ) ومن ثم حساب معادالت الكاينماتيك الخاصة للحصول على موقع االرجل على االرض والالزمة لتحقيق االستقرارية الثابتة creeping gaitطيء(الب للروبوت اثناء المشي. ومن بعدها تم الحصول على النتائج الالزمة لتحقيق هذه االستقرارية من خالل مواقع االرجل على االرض. 28-39اسماء al-khwarizmi engineering journal,vol. 13, no. 1, p.p. experimental and numerical asmaa ali hussein foundation of techni email: (received 4 september https://doi.org/10.22153/kej.2017.01.001 abstract all central air conditioning systems contain piping system with various components, sizes, material, and layouts. if such systems in operating mode, the flow in piping system and its component such as vibration due to some flow phenomenon’s. in used to study the flow-induced vibration in valves. computational fluid dynamics (cfd) concepts are included with one-way and two-way fluid-structure interaction concepts by using finite element software package (ansys 14.57). detection analysis is performed on flow characteristics under operation conditions vibration. most of real geometrical, operational, and boundary conditions are simulated to obtain best similarity with real operation conditions. comparisons performed between experimental data and numerical results (one way simulation) to verify the results. the main vibration for valve is the water pulsation in addition to amount of water hammering water pulsation in globe valve is the vortex shedding and pressure differe valve. the vibration amplitude was increased with increasing flow rate 30% and then decreased until flow rate reaches to around 85% and then trends to be constant. keywords: flow-induced vibration, vortex shedding, pressure pulsation, v transform (fft). 1. introduction the vibration in piping system and its component especially valves can occurs due to many reasons. some of these reasons related to unavoidable flow phenomenon such as turbulence cavitation, vortex shedding, and pressure pulsation. the other reasons related to structural behavior such as the resonance between the long pipeline and the other vibrating equipment such as pumps. the high level of vibration in piping system can cause breakdowns because the noise, fracture, and fatigue failure. the reduction of vibration level in such systems is a valuable task to avoid breakdown. the reduction vibration requires a wide knowledge of vibration source, causes, types, and how can to eliminate or reduce the causes. the prior investigation of flow khwarizmi engineering journal,vol. 13, no. 1, p.p. 2839 (2017) experimental and numerical research on flow-induced vibratio valves asmaa ali hussein foundation of technical education/ baghdadiraq email: asmaa31930@yahoo.com september 2016; accepted 3 january 2017) https://doi.org/10.22153/kej.2017.01.001 all central air conditioning systems contain piping system with various components, sizes, material, and layouts. if the flow in piping system and its component such as valves can produce severe in this research, experimental measurements and numerical simulation are induced vibration in valves. computational fluid dynamics (cfd) concepts are included with structure interaction concepts by using finite element software package (ansys 14.57). on flow characteristics under operation conditions and relations with structural geometrical, operational, and boundary conditions are simulated to obtain best similarity with performed between experimental data and numerical results (one way simulation) to verify the results. the main conclusion was drawn from the study that the dominant source of vibration for valve is the water pulsation in addition to amount of water hammering. in addition, the main source of water pulsation in globe valve is the vortex shedding and pressure difference between upstream and downstream of with increasing flow rate until to be maximum when the flow rate around 30% and then decreased until flow rate reaches to around 85% and then trends to be constant. vortex shedding, pressure pulsation, valve, finite element, ansys the vibration in piping system and its component especially valves can occurs due to reasons related to such as turbulence, avitation, vortex shedding, and pressure related to structural the resonance between the long pipeline and the other vibrating equipment such as high level of vibration in piping because the leaks, reduction systems is a valuable the reduction of a wide knowledge of vibration to eliminate or ation of flow behavior and flow-induced vibration of such system will give a most important knowledge for optimum anti vibration design. the valve is one of the main components of any piping system. behavior of flow inside the valve and between the flow and valve structure components can be the source of severe vibration fletcher [1] introduced a theoretical oscillations of piping fittings conclusion from this study is t typical ranges of acoustic resistance is possible. the analysis process t oscillations of little amplitude. lighterink [2] presented a paper described examine the loads on tools due to the vibrations. investigations performed on a piping system with standard equipment to investigate: a) the vibrational natural mode shape of the piping, al-khwarizmi engineering journal induced vibration in all central air conditioning systems contain piping system with various components, sizes, material, and layouts. if valves can produce severe research, experimental measurements and numerical simulation are induced vibration in valves. computational fluid dynamics (cfd) concepts are included with structure interaction concepts by using finite element software package (ansys 14.57). and relations with structural geometrical, operational, and boundary conditions are simulated to obtain best similarity with performed between experimental data and numerical results (one-way and twothat the dominant source of in addition, the main source of nce between upstream and downstream of to be maximum when the flow rate around ansys, fast fourier induced vibration of such a most important knowledge for the valve is one of of any piping system. the behavior of flow inside the valve and interaction between the flow and valve structure components the source of severe vibration. n. h. theoretical study on the piping fittings. the main that there exist resistance for oscillation the formation of . lighterink et. al ] presented a paper described a method to due to the mechanical performed on a piping to investigate: a) the vibrational natural mode shape of the piping, pdf created with pdffactory trial version www.pdffactory.com https://doi.org/10.22153/kej.2017.01.001 mailto:asmaa31930@yahoo.com https://doi.org/10.22153/kej.2017.01.001 http://www.pdffactory.com http://www.pdffactory.com asmaa ali hussein al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 2839 (2017) 29 b) the natural mode shapes of the piping and equipment, and c) the total loads on the equipment. ravi pankhania et. al [3] carried out study on vibration of piping equipment for nuclear application. the study included design and analysis of motor operated flow control used for nuclear application. malik i. alamayreh et.al [4] presented a research on butterfly valve for vibration reduction. the work included numerical simulation of a butterfly valve used to control the flow rate in industrial process. present research includes experimental and numerical investigation on flow-induced vibration in globe valve. 2. numerical simulation computation fluid dynamics (cfd) with the aid of finite element software package (ansys 14.57)is used in the current study. this program analyzes and solves a wide range of different mechanical problems, such as the structural, fluid flow, thermal, and the fluid-structure interaction problems [5]. ansys mechanical (apdl 14.57)is used for structural analysis and ansys (fluent 14.57) is used for fluid analysis and ansys workbench is used for fluid-structure interaction analysis. cfdisused to investigate the flow characteristics for the vicinity of valve. the flow characteristics included pressure and velocity distribution, velocity vector, vortex, cavitation regions, and the integrated dynamic forces on the structure. fsi applications involve coupling of fluid dynamics and structure mechanics disciplines: 1) fluid flow exerts hydrodynamic forces on a structure and deforms and/or translates the structure. 2) deformed or translated structure impart displacement to the fluid domain and changes its shape and thus changes the fluid flow. there are two modes of fsi. one-way solution used with conditions of very small of deformations in the structure. the solver calculates and passes flow fields from cfd to the structural analysis and no need to update and recalculate flow. two-way is used when large structural deformations is included where iterate between fluid solution and structural solution until the convergence is obtained. both 1-way and 2way fluid-structure simulation are used in current research. the coupling of twoway solution is shown in figure (1) [6].the aims of using the two simulations is to establish the accurate and best simulation for the problem and specify which mode of fsi give results close to experimental results. the numerical simulation will give good visualization of flow behavior inside the valves. numerical simulation setup requires choosing the perfect geometry representation, suitable element type, boundary conditions, and material properties. 2.1. element type two types of element used in current research. for structural analysis, shell281is used. the element has eight nodes with six degrees of freedom at each node. for fluid analysis, higher order tetrahedral element (10 node) with hanging nodes is used. figure (2) shows the elements type. 2.2. boundary condition for structural analysis, clamped boundary (all degrees of freedom = 0) used at the beginning and the end of valves to simulate the flanged connection of valves with piping system. for fluid analysis, velocity inlet boundary (v= 1m/s) used at the inlet of valve and wall boundary(v = 0) used to bound fluid and solid contact. 2.3. material properties the fluid used as flow material is water at average temperature 15 ̊c. the standard values of density and viscosity of water at this temperature used in numerical simulation. the material of valve body is cast iron. the standard values of mechanical properties (density, modulus of elasticity, and poissons ratio) according to astm for cast iron are used in structural analysis. 2.4. simulation setup the one-way simulation included the transient fluid flow solution for time history of pressure distribution and then export the pressure solution at each time step to transient structural solution to obtain the time history of vibrational displacement. the solution results data obtained and then plotted with the aid of suitable graphic program. the two-way simulation included coupling solution of flow and structural solution to obtain the vibrational displacement directly. the fundamental steps associated with the application of the finite element method to solve problems in fluid simulation showed in the diagram in figure (1) [7]. pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com asmaa ali hussein al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 2839 (2017) 30 fig. 1. coupling procedure and numerical simulation steps. fig. 2. element type. 3. theoretical background 3.1. flow analysis when dealing with water flows, some assumptions included: 1three dimensional flow, 2-incompressible flow, 3-newtonian fluid. the governing equations of flow can be summarized by [8]: (i) mass conservation (continuity equation) equating the quantity of mass entering and leaving an element volume is: 0= ¶ ¶ + ¶ ¶ + ¶ ¶ z w y v x u ... (1) where: x, y, and z are the cartesian coordinates. u, v, and w are the velocity component in direction of x, y, and z respectively [m/s]. (ii) momentum conservation (navier–stokes equations) momentum conservation equation is: in xdirection : pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com asmaa ali hussein al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 2839 (2017) 31 )( )( 2 2 2 2 2 2 z u y u x u g z uw y uv x uu x p x ¶ ¶ + ¶ ¶ + ¶ ¶ += ¶ ¶ + ¶ ¶ + ¶ ¶ + ¶ ¶ m rr ... (2) -in ydirection : )( )( 2 2 2 2 2 2 z v y v x v g z vw y vv x vu y p y ¶ ¶ + ¶ ¶ + ¶ ¶ += ¶ ¶ + ¶ ¶ + ¶ ¶ + ¶ ¶ m rr ... (3) in zdirection : )( )( 2 2 2 2 2 2 z w y w x w g z ww y wv x wu z p z ¶ ¶ + ¶ ¶ + ¶ ¶ += ¶ ¶ + ¶ ¶ + ¶ ¶ + ¶ ¶ m rr … (4) where: p: pressure (n/m2) ρ: fluid density (kg/m3) g: gravitational acceleration (m/s2) μ: viscosity (n.s/m2) the comprehensive formulation of above equations in finite element analysis detailed in reference [9]. 3.2. structural analysis the vibration responses of any continous structure due to external load can be evaluated by using numerical technique to solve the equation of motionwhich can be written as [9]. [�]�̈̅ + [�]�̇̅ + [�]�̅ = ��(�) ...(5) �̈̅ = [�]�� (��(�) − [�]�̅ − [�]� �̇ ) …(6) where: [m]: mass matrix [kg] [c]: damping coeficient matrix [kg/s] [k]: stifness matrix [kg/s2] �, �,̇ �̈: displacement, velocity andacceleration of structural particle respectively. the complete procedure of numerical solution for above structural equations presented in reference [9]. 4. experimental work experimental work included vibration measurements for piping system components. the experimental tests performed on the piping of central air conditioning system in university of baghdad because this system suffers severe mechanical vibration. the piping system contains many components such as valves, strainers, elbows, tees, and flow meters. the flow rate inside the system can be controlled with the aid of pumps and valves. the vibration measuring system can be used for this purpose. this system included three-axis accelero meter which can be mounted on any position in piping system to measure the dynamic acceleration of vibrational structure. then, the output acceleration signal goes to analog to digital convertor (adc) card and then showed and recorded by using suitable computer software. figure (3)shows the flow of vibration signal and apparatus of vibration signal measurements used in the current research. the accelerometer attached rigidly to the structure to measure the acceleration at any point in the structure in the form of signal. the more details and calibration of the vibration measuring devices performed and detailed in reference [10]. 5. description of piping system all experimental tests performed on the piping network of central air conditioning system of the central library in university of baghdad. the network consists of pipes with different diameters, lengths, and thickness. also, there are many types of valves such as gate valve, balance valve, globe valve, and check valve. the vibration measurements performed on globe valve of piping network. pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com asmaa ali hussein al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 2839 (2017) 32 fig. 3. flow diagram of vibration signal and vibration measurement devices. 6. analysis procedure the most important task is to establish a feasible, precise, and logical analysis for the obtained experimental and numerical data. precise analysis will lead to precise results and conclusions. in the current research, specific procedureis used to analyze the obtained data. this procedure consists of the following steps: 1. obtain the experimental data from vibration measurement tests for globe valve. the vibration dataplotted in both time domain and frequency domain. 2. make suitable and precise numerical simulation for the flow inside the valve, which examined experimentally at step 1 3. from the numerical simulation of step 2, the response of piping system to flow excitation which is the time history of structure displacement (vibration) due to flow dynamic forces can be obtained. these structure displacements (vibration) obtained from both 1-way and 2-way numerical simulations. 4. make a precise correlation between the numerical results of structure vibration and flow characteristics to find the real reasons of structure vibration. 5. make precise comparisons between the results of structure vibration obtained from experimental tests and numerical simulations. 6. make feasible and precise correlation between the experimental results of structure vibration and flow characteristics obtained from numerical simulations 7. establish the conclusions. 7. results and discussions the schematic diagram of the components of globe valve is shown in the figure (4). it mainly consists of two important regions: flow domain which the space occupied by fluid and contains all flow phenomenon's which the main cause of dynamic fluid forces and the pipe wall which represents the structure domain whose vibration is to be measured. fig. 4. schematic diagram of globe valve. the geometry of the flow domain is an important parameter for initiation and formation of the flow phenomenon. figure 5 shows the meshed flow domain for numerical simulation at different enclosure ratio. pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com asmaa ali hussein al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 2839 (2017) 33 fig. 5. flow domain at different enclosure ratio. figures6 and 7 show the velocity distribution and pressure distribution obtained from numerical simulation. the distribution of pressure and velocity over the flow domain depends mainly on amount of enclosure of the valve. figure6 shows the pressure distribution at enclosure 100%, 80% and 60% respectively while figure 7shows the velocity distribution for the same enclosure ratio respectively. the entrance flow velocity is 1m/s. fig. 6. pressure distribution over the flow domain of globe valve at different enclosure ratio. pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com asmaa ali hussein al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 2839 (2017) 34 fig. 7. velocity vector distribution over the flow domain of globe valve at different enclosure ratio. figure 8and 9 show the dynamic response (vibration) on the valve wall obtained from 1-way and 2-way numerical solution respectively in both time and frequency spectrum (fft). these results obtained from numerical simulation as a table of time history of wall displacement and then drawn by using graphic program.figure10shows the experimental vibration measurement for the same valve with enclosure of 30%obtained by experimental test in both time and frequency spectrum (fft). fig. 8. displacement of globe valve obtained from numerical solution 1-way. pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com asmaa ali hussein al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 2839 (2017) 35 fig. 9. displacement of globe valve obtained from numerical solution 2-way. fig. 10. time domain and frequency spectrum (fft) of experimental vibration signal of globe valve. it is obvious that the vibration measurements will determine the frequency spectrum and the amplitude of vibration but does notsupply details about the source of shaking because the absolute value of vibration does not give a suitable knowledge about the flow behavior and vibration source inside the piping system. the first observation on the vibration data is that the behavior of experimental measured vibration signal is close to that obtained from 1-way numerical simulation than that obtained from 2way numerical simulation. experimental tests show that the vibration signal was repeated with approximately constant frequency (336hz)and amplitude (0.4mm)and there is one distinguish peak in frequency spectrum. similarly, the 1-way simulation provides repeated vibration signal with some noise and frequency spectrum shows one distinguish peak. the vibration signal obtained from 2-way simulation has remarkable decay in amplitude and changing frequency until approaches to convergence state. in addition, the frequency spectrum shows more than one distinguish peak (300hz). this is an important observation because it confirms the validity of numerical simulation. the 2-way numerical simulation is an important issue when the structure undergoing large deflection vibration. this observation indicates that 1-way fsi simulation is sufficient to estimate the dynamic response of piping structure in current study where the vibration of valve can be considered as small deflection vibration. different operation conditions, support type, material size, types, and boundary conditions of the same structure may be made 1-way fsi simulation not sufficient to pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com asmaa ali hussein al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 2839 (2017) 36 predict the dynamic response (vibration). the second and most important observation on the vibration results that the response of valve to flow excitation is approximately repeated with amount of noise in the form of random vibration. this indicates that the dominant source of vibration can be water pulsation or water hammering or vortex shedding because all these sources provide a regular excitation wave. water pulsation and water hammering are including pressure waves. water pulsation included steady oscillation with small amplitude. this small amplitude can be developed and enlarge if the resonance conditions are realize while the water hammering is unsteady transient oscillations with large amplitude. the water hammering may occured in valves and pumps but it is related to fluid –structure interaction. the comparisons between the experimental vibration data and the numerical simulation results show that no significant fsi was established for current case study. this observation proves that the dominant source of vibration for valve is the water pulsation in addition to amount of water hammering. now, it is a valuable to specify the source of water pulsation for flow in valves. by return to figures 6 and 7, the main source of water pulsation is the vortex shedding and pressure difference between upstream and downstream of valve. figure 7 shows many circulation regions which can be the source of vortex. the vortex shedding is a regular flow phenomenon can cause regular pressure wave which in turn excite the structure to vibrate. figure 6 shows high reduction of pressure cross the valve section. the pressure reduction causes the high amount of turbulence energy transferred into the system and can be the source of associated random vibration (noise).in addition, the appearance of one distinguish peak in frequency spectrum for both experimental and 1way numerical simulation proves that the system may vibrates close to one natural mode of vibration. this phenomenon called lock-in where the frequency of vortex shedding coincides with one of the natural frequencies of the system. the other subsequent result from vibration data and flow characteristics that the vibration of valve depends on the flow path and the flow rate of water sincethe flow characteristics (velocity and pressure)distribution has strong dependency on the amount of valve enclosure (flow path) as shown in figures 6-7. figure 11 shows the vibration measurement data (displacement signal) of globe valve measured at different flow rate cross the valve (enclosing percentage). fig. 11. displacement measurement of globe valve at different flow rate cross the valve. it is obvious from the figure that the vibration amplitude increases with increasing of flow rate to be maximum when the flow rate around 30% and then decreased until flow rate reaches to around 85% and the trends to be constant as shown in figure 12. pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com asmaa ali hussein al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 2839 (2017) 37 fig. 12.vibration amplitude of globe valve versus flow rate cross the valve. [experimental data]. this behavior of vibration is related to flow characteristics as mentioned. figure 7 shows that severe flow conditions (high pulsation and vortex shedding) between enclosure percentages 80-60% [flow rate 20-40%]. this confirms the previous results. the dependency of vibration level on flow characteristics (flow phenomenon's, flow path, flow rate, pressure distribution, and velocity distribution) requires other experimental and numerical analysis on valve of different geometry. 7. conclusion 1. experimental tests show that the structural vibration signal was approximately repeated with approximately constant frequency (336hz) and amplitude with little noise signals. this can be shown from fft of experimental data where one distinguish peak represent the dominant vibration frequency and many small peaks represent the noise. 2. there is one distinguish peak in frequency spectrum for experimental vibration measurement. 3. the behavior of experimental measured vibration signal of valve is close to that obtained from 1-way numerical simulation than that obtained from 2-way numerical simulation. therefore, the 1-way fsi simulation is sufficient to estimate the dynamic response (vibration) of valve because it can be considered as small deflection vibration. 4. the dominant source of vibration of valves can be water pulsation or water hammering or vortex shedding because all these sources provide a regular excitation wave with approximately constant frequency at steady state of velocity and pressure. 5. the dominant source of vibration for globe valve established in current study is the water pulsation in addition to amount of water hammering 6. the main source of water pulsation in globe valve is the vortex shedding and pressure difference between upstream and downstream of valve. 7. the vibration of valve dependent on the flow path and the flow rate of water since the flow characteristics (velocity and pressure) distribution has strong dependency on the amount of valve enclosure (flow path) 8. the vibration amplitude increases with increasing of flow rate to be maximum when the flow rate around 30% and then decreased until flow rate reaches to around 85% and then trends to be constant nomenclature 8. references [1] n. h. fletcher, "autonomous vibration of simple pressure-controlled valves in gas flows", j. acoustic. soc. am. 93(4), pt. 1, april 1993. [2] n.e. ligterink, r. de groot, h.j. slot , emad gharaibah, "flow induced vibration of subsea gas production systems caused by choke valves", spe annual technical conference and exhibition held on 8-10 october 2012, san antonio, texas. copyright 2012, society of petroleum engineers. description symbol cartesian coordinates. x, y, and z velocity component in direction of x, y, and z respectively. u, v, and w pressure (n/m2) p fluid density (kg/m3) ρ gravitational acceleration (m/s2) g viscosity (n.s/m2) μ mass matrix [kg] [m] damping coefficient matrix [kg/s] [c] stiffness matrix [kg/s2] [k] displacement, velocity and acceleration of structural particle respectively. � , �̇ , �̈ : pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com asmaa ali hussein al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 2839 (2017) 38 [3] ravi pankhania, dhaval patel and v.m. bhojawala, "free vibration analysis of a motor operated gate valve for nuclear application using finite element analysis", international journal of advanced mechanical engineering. issn 2250-3234 volume 4, number 3 (2014), pp. 349-356. [4] malik i. al-amayreh, mohammad i. kilani, ahmed s. al-salaymeh, " numerical study of a butterfly valve for vibration analysis and reduction" international journal of mechanical, aerospace, industrial, mechatronic and manufacturing engineering vol:8, no:12, 2014. [5] ansys theory reference. twelve edition, 2009, ansys inc., south point, canonsburg, [6] h. h. hamad, "dynamic response of solar collector for self-cleaning", ph.d thesis, university of technology, 2012. [7] c. taylor and t. g. hughes, ˝finite element programming of the navier-stokes equations”, bell and bain ltd., 1st published, 1981. [8] sinan a. ali “ study effect of riblet upstream wing-wall junction numerically and experimentally” ,m.sc. thesis, mechanical eng. dept. university of technology, 2011. [9] friedel hartmann casimir katz “structural analysis with finite elements” springerverlag berlin heidelberg 2007. [10] ihsan.a. baqer, "modeling of 3d grasping of artificial hand under dynamic load", ph.d thesis, university of technology, baghdad, 2014. pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com )2017( 28-39 صفحة ،2العدد ،13المجلد الھندسیة الخوارزمي جلةم اسماء علي حسن 39 على االھتزاز الناتج عن الجریان في الصمامات بحث عملي وعددي علي حسین أسماء العراق_ بغداد/ ھیئة التعلیم التقني asmaa31930@yahoo.com:البرید االلكتروني الخالصة عندما تكون ھذه االنظمة في حالة . تحتوي على منظومة انابیب مع ملحقات وقیاسات ومواد ومخططات متنوعةجمیعھا تكییف الھواء المركزیة أنظمةإن تم اجراء ، في البحث الحالي. بسبب بعض ظواھر الجریان اً حاد اً تشغیل فان الجریان في منظومة االنابیب وملحقاتھا مثل الصمامات یمكن ان ینتج اھتزاز تم استخدام مفھوم دینامیك الموائع العددي ومفھوم التفاعل بین المائع . عملیة والمحاكاة العددیة لدراسة االھتزاز الناتج عن الجریان في الصماماتالالقیاسات تم اجراء تحلیل تنبؤي على خصائص ). ansys 14.57(د طریقة العناصر المحددة والھیكل باتجاه واحد وباتجاھین باستخدام برنامج حاسوبي یعتم . تم محاكاة اغلب الظروف الھندسیة والحدیة للحصول على افضل تشابھ مع الظروف الحقیقیة. الجریان تحت ظروف التشغیل والعالقة مع اھتزاز الھیكل اھم النتائج . اسات العملیة والمحاكاة العددیة للتحقق من النتائج والحصول على نتائج دقیقةتم اجراء مقارنات بین النتائج المستحصلة من القیوكذلك المصدر الرئیس لنبضات الماء في كذلك ان . طرق الماء فضال عنلالھتزاز داخل الصمامات ھو نبضات الماء المستخلصة من الدراسة ان المصدر الرئیس ایضا وجد ان سعة االھتزاز تزداد بازدیاد معدل الجریان لتصل الى . الخروج للصماموق الضغط بین مجرى الدخول الصمام الكروي ھو انبثاق الدوامات وفر . ومن ثم تبقى ثابتة تقریبا% ٨٠ومن ثم تنخفض الى ان یصل معدل الجریان حوال % ٣٠اعلى قیمة عند حوالي معدل جریان pdf created with pdffactory trial version www.pdffactory.com mailto:asmaa31930@yahoo.com http://www.pdffactory.com http://www.pdffactory.com 44-59 al-khwarizmi engineering journal,vol. 11, no. 4, p.p. hexapod robot static stability enhancement using genetic firas a. raheem *,**department of (received abstract hexapod robot is a flexible mechanical robot with six legs. it has the ability to walk over terrain. the hexapod robot look likes the insect so it has the same gaits. these gaits are statically stable at all the times during each gait in order not to fall with three or more legs continuously contacts with the ground. the safety static stability walking kinematics are derived for each hexapod r2010a for all gaits and the geometry in order to derive the equations of the sub hexapod’s leg. they are defined as the sub with each other and they are useful to keep the legs stable from falling during each gait. a smooth gait was analyzed and enhanced for each hexapod’s leg in two phases, stance phase and swing phase. two approaches first, the modified classical stability margins. in this approach, the range of stability margins is evaluated for all gaits. the second method is called static stability by getting the best stability margins for hexapod robot planning of hexapod robot with smaller error than the first approach and with better new stable coordinates of legs tips than the first method. in addition, the second approach is useful for getting the better new stable center body coordinates than center body coordinates in the first approach of hexapod robot. keywords: kinematics, stability margin, 1. introduction the hexapod robots are mechanical vehicles that walk with six legs; they have attracted considerable attention in recent decades. there are several benefits for hexapods rover efficient one to maintain for statically stable static on three or more legs, it has a great deal of flexibility in how it can move [1]. difficult problem of generation and control of the sequences of placing and lifting legs such that any instant body should be stable and moving from one position to other. the gait is defined as generation and sequences of legs during the hexapod motion [2]. hexapod robot looks like insect so it has the same gaits [1]. the of hexapod are: wave, ripple, and tripod gait [3]. the ga is determined the optimal movement khwarizmi engineering journal,vol. 11, no. 4, p.p. 4459 (2015) hexapod robot static stability enhancement using genetic algorithm firas a. raheem* hind z. khaleel** of control and systems engineering / university of technology *email: dr.firas7010@yahoo.com **email: hhindzuhair@yahoo.com (received 22 march 2015 ; accepted 30 june 2015) is a flexible mechanical robot with six legs. it has the ability to walk over terrain. the hexapod robot look likes the insect so it has the same gaits. these gaits are tripod, wave and ripple gaits. hexapod robot needs to stay times during each gait in order not to fall with three or more legs continuously contacts with static stability walking is called (the stability margin). in this paper, for each hexapod’s leg in order to simulate the hexapod robot model walking for all gaits and the geometry in order to derive the equations of the sub-constraint workspaces for each hexapod’s leg. they are defined as the sub-constraint workspaces volumes when the legs are moving without collision with each other and they are useful to keep the legs stable from falling during each gait. a smooth gait was analyzed and enhanced for each hexapod’s leg in two phases, stance phase and swing phase. the propose the modified classical stability margins. in this approach, the range of stability margins is evaluated for all gaits. the second method is called stability margins using genetic algorithm (ga) the best stability margins for hexapod robot and these results are useful to get best stable path planning of hexapod robot with smaller error than the first approach and with better new stable coordinates of legs tips first method. in addition, the second approach is useful for getting the better new stable center body coordinates than center body coordinates in the first approach of hexapod robot. argin, workspace, genetic algorithm and hexapod robot. robots are mechanical vehicles that walk with six legs; they have attracted considerable attention in recent decades. there are s rover such as: efficient one to maintain for statically stable static on three or more legs, it has a great deal of flexibility in how it can move [1]. there is a generation and control of the sequences of placing and lifting legs such that at any instant body should be stable and moving from one position to other. the gait is defined as generation and sequences of legs during the robot looks like the three gaits e, ripple, and tripod gait is determined the optimal movement by the hexapod leg for walking robot with three degrees of freedom, with higher positioning precision by using an analytical hierarchy process [4]. the stability of problem to maintain it from fall during its walking with using the (ga) in order to get the optimal movement. hexapod simulation with a used to determine the robot's movements for generating chromosomes which are created from repeated sequence of static leg positions, the fitness function equation using the main factor stability and efficiency [5]. the objective function is used as the stability margin to find optimal walking gaits for an 8-legged robot as in [6]. in this paper the main problem is when hexapod robot walking and may be fall down if the legs are not constraints so the are analyzed, one that called the al-khwarizmi engineering journal (2015) hexapod robot static stability enhancement using genetic hind z. khaleel** technology is a flexible mechanical robot with six legs. it has the ability to walk over terrain. the hexapod robot . hexapod robot needs to stay times during each gait in order not to fall with three or more legs continuously contacts with . in this paper, the forward and inverse simulate the hexapod robot model walking using matlab constraint workspaces for each es when the legs are moving without collision with each other and they are useful to keep the legs stable from falling during each gait. a smooth gait was analyzed the proposed work focused on the the modified classical stability margins. in this approach, the range of stability margins is stability margins using genetic algorithm (ga) that enhanced the and these results are useful to get best stable path planning of hexapod robot with smaller error than the first approach and with better new stable coordinates of legs tips first method. in addition, the second approach is useful for getting the better new stable center body obot. leg for walking robot with three degrees of freedom, with higher positioning precision by using an analytical hierarchy the stability of hexapod is a main problem to maintain it from fall during its walking the (ga) in order to get the optimal simulation with a (ga) are used to determine the robot's movements for generating chromosomes which are created from a repeated sequence of static leg positions, the fitness function equation using the main factor stability and efficiency [5]. the objective function is used as the stability margin to find optimal legged robot as in [6]. er the main problem is when robot walking and may be fall down if the legs are not constraints so the two approaches one that called the modified firas a. raheem classical stability margins is depended on according to constraints of each leg in order fall and the other approach is called margins enhancement using genetic algorithm is based on the stable ranges values that getting from first approach. the genetic algorithm is used to get the best stability margins and these results useful to get best stable path planning robot. 2. modeling of hexapod robot the legged locomotion verities by verity of usual terrain and it presents a set of difficult problems (foot placement, obstacle avoidance, load distribution, common stability) which must be taken into account both in mechanical construction of vehicles and in development of control strategies [7]. besides that, these issues are using models that mathematically explain the verities of situations and for that; th modeling becomes a practical tool in understanding systems complexity and for testing and simulating diverse control approaches the robot structure considered has (6) identical legs and each leg has (3) degree of freedom, in addition to that, all the related points for each joint have been put on the model, the legs numbering as shown in figure 1, robot’s coordinate o (xo, yo, zo). fig. 1. hexapod robot structure the z-axis pointing up, the x forward and the y-axis pointing left to right hand rule. hexapod robot consisting of two types, one is forward kinematic and its inverse, below will discuss in deta each type of kinematic. al-khwarizmi engineering journal, vol. 11, no. 45 is depended on f each leg in order not to fall and the other approach is called stability using genetic algorithm is that getting from the genetic algorithm is used to these results are path planning of hexapod modeling of hexapod robot the legged locomotion verities by verity of usual terrain and it presents a set of difficult problems (foot placement, obstacle avoidance, common stability) which must be taken into account both in mechanical construction of vehicles and in development of . besides that, these issues are using models that mathematically explain the verities of situations and for that; the robot modeling becomes a practical tool in understanding systems complexity and for testing ting diverse control approaches [8]. the robot structure considered has (6) identical legs and each leg has (3) degree of freedom, in all the related points for each joint have been put on the model, the legs 1, robot’s center robot structure. axis pointing up, the x-axis pointing and according robot modeling consisting of two types, one is forward kinematic and its inverse, below will discuss in details for 2.1. forward kinematics for one leg hexapod robot the successful design of a legged robot depends to a large amount on the leg design chosen. since all aspects of walking are ultimately governed by the physical limitations of the leg, it is important to select a leg that will allow a maximum range of motion a unnecessary constraints on the walking. three-revolute kinematical chain been chosen for each leg mechanism in order to imitate the leg structure as shown in fig direct geometrical model for each leg mechanism is formulated between the moving frame oi(xi,yi,zi) of the leg base, where i=1… fixed frame o (xo,yo,zo) [9]. fig. 2 .model and coordinates frame for leg kinematics. in this paper, the bh3is taken as a case study lengths of the hexapod’s leg = (5.7 cm), l3 = (10.8 cm frame starts with link (0) which is the robot body where the leg is jointed to; link (1) is the coxa, link (2) is the femur and link (3) is the tibia. legs are distributed symmetrically around the axis in the direction of motion ( the general form for the transformation matrix from link (i) to link (i-1) using denavit hartenberg parameters is given in the d1 r1 θ1 z1 l1 x0 yo zo xc leg base θ3 khwarizmi engineering journal, vol. 11, no. 4, p.p. 4459 (2015) rd kinematics for one leg of successful design of a legged robot depends to a large amount on the leg design chosen. since all aspects of walking are ultimately governed by the physical limitations of the leg, it is important to select a leg that will allow a maximum range of motion and not inflict onstraints on the walking. the revolute kinematical chain (r1, r2, r3) has been chosen for each leg mechanism in order to imitate the leg structure as shown in figure 2. a direct geometrical model for each leg mechanism formulated between the moving frame ) of the leg base, where i=1…6, and the [9]. l and coordinates frame for leg -r hexapod robot model case study of hexapod robot. the ’s leg are: l1 = (2.9 cm), l2 10.8 cm) [10]. the robot leg frame starts with link (0) which is the point on the robot body where the leg is jointed to; link (1) is the coxa, link (2) is the femur and link (3) is the tibia. legs are distributed symmetrically around direction of motion (x in this case). the general form for the transformation matrix ) using denavit hartenberg eq. 1 [9,11]: r2 x1 l2 r3 l3 x3 z3 x2 z2 y0 θ2 firas a. raheem al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 4459 (2015) 46 t���� = �cosθ� −sin θ� cos α�sinθ� cos θ� cos α� sin θ� sinα� a� cosθ�−cos θ� sin α� a� sinθ�0 sinα�0 0 cos α� d�0 1 � …(1) the transformation matrix is a series of transformations: 1. translate di along zi-1 axis. 2. rotate θ�about zi-1 axis. 3. translate a� about xi-1 axis (a�= li for i=1...3). 4. rotate α� about xi-1 axis. the overall transformation is obtained as a product between three transformation matrixes: t�������� = t��������� t����� ���� …"2$ considering figure 2 and using eq. 2 the coordinates of the leg tip are: x = cosθ� ∗ "l� + l) ∗ cosθ) + l*∗ cos"θ) − θ*$$, y = sinθ� ∗ "l� + l) ∗ cosθ)+ l* ∗ cos"θ) − θ*$$, z = d� + l) ∗ sinθ)+ l* ∗ sin"θ) − θ*$ … "3$ where: d1 is the distance from the ground to the coxa joint. li are the lengths of the leg links. 2.2. inverse kinematics using geometric approach the inverse kinematics problem consists of formative the joint angles from a given position and orientation of the end frame. the solution of this problem is significant in order to transform the motion assigned to the end frame into the joint angle motions matching to the desired end frame motion. the goal is to find the three joint variables θ1, θ2, and θ3 corresponding to the desired end frame position. the end frames orientation is not a matter, where only paying attention in its position [9]. fig. 3 . illustrations for solving inverse kinematics. using eq. 3 and considering the following constraints: all joints allow rotation only about one axis, femur and tibia always rotate on parallel axes, and the physical limitation of each joint can determine the joint angle. the coxa joint angle can be found using the following function as can be seen from figure 3 a. θ� = tan�� 0y�x�1 … "4$ in order to determine the other two angles a geometrical approach is considered. the leg tip coordinates were transformed to coxa frame using the transformation matrix below: t��������� = 0"r��������� $ −"r��������� $4 ∗ d���������0 1 1 …"5$ the angle θ) of the femur servo position can be derived directly from the triangle figure 3 b. θ) = φ − φ� … "6$ the angle φ� is the angle between the x-axis and line a and can be calculated with the following function: φ� = tan�� 0y*x*1 … "7$ where x3 and y3 are the leg tip coordinates in coxa frame. the law of cosine results is applied: φ = cos�� 9l)) + a) − l*)2 ∗ l) ∗ a : … "8$ where: a = <=*) + >*) … "9$ from the eq. 6, the femur angle can be found from[9]: l leg tip x1, y1 y femur joint coxa joint tibia joint l2 θ* θ) φ* φ� x3,y3 a a b y x x φ firas a. raheem al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 4459 (2015) 47 θ) = cos�� 9l)) + a) − l*)2 ∗ l) ∗ a :− tan��"y*, x*$ … "10$ by applying the law of cosines, the φ* angle is found: φ* = cos�� 9l)) + l*) − a)2 l) ∗ l* : … "11$ considering figure 3 b, the @* can be found as follows [9]: θ* = π− φ3 … "12$ 3. workspace of hexapod’s leg in this paper the hexapod's leg workspace has been computed and analyzed. hexapod's leg workspace can defined as the set of reachable points by the end-effector for each foot. these points (positions) depended on the leg orientation (the mechanical limits of the joints). the mechanical limits of the joints restrict leg motion and are a major factor to consider when developing walking algorithm for a hexapod module. the working volumes for each leg are identical because each leg of hexapod has the same geometrical configuration and joint limits; the analyzed of the two approaches to evaluate the constraint workspace for bh3-r hexapod robot [10]. the limits of the joint variables for a representative one leg are shown in table 1 [10]. table 1. the range of angles for one hexapod’s leg [10]. link name the range of one robot’s leg angle in degree coxa −90 < @� < 90 femur −45 < @) < 90 tibia 0 < @* < 135 these joint variable limits, then, separate the reachable area from the unreachable area. reachable areas move with the body. the region included within the reachable area is known as the unconstrained working volume (uwv). the constrained working volume (cwv) is defined as a subset of the original working volume, for each leg, that ensures static stability. therefore, the (cwv) sets soft limits for each leg so as to exclude points from the working volume that may lead to instability. in our case, the working volume is also constrained to prevent leg collisions. an excluded area for hexapod's legs, then, is that part of the reachable area where, if a foot were placed there, instability or leg collision might result. fig. 4. flowchart workspace of hexapod’s leg. figure 4 shows that the flowchart of workspace. the workspace of robot leg is computed from kinematics and geometry as follow: 3.1. unconstrained workspace the unconstrained horizontal workspace of hexapod leg is the reachable areas include the sections in the xy plane around the individual coxas and within the mechanical joint limits, the y plane equal (30 cm). the unconstrained vertical workspace, or z-plane reachable area, depends on the height of the hexapod’s center-of-body above the terrain is (5.5 cm). to define the maximum unconstrained vertical workspace, if a leg were extended to its fullest, the added lengths of radius body (13.75 cm), coxa (2.9 cm), femur (5.7 cm), and tibia (10.8 cm) yplane would equal (30 cm). the minimum unconstrained vertical workspace, if a leg were lack extent to its fullest, (i.e θ* = 1350), the yplane would equal (14.7 cm) while the z-plane equals to (9 cm). 3.2. constrained workspace the calculations of cwv results are used for six basic constraints: • the height (z = plane) from the ground to the cb (center body of robot) = (10.8 cm) is fixed for minimum, maximum reach, the vertical maximum firas a. raheem al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 4459 (2015) 48 reach equal (24.25 cm) if θ* = 800 and minimum reach equal (21 cm) if θ* = 97o, • the suitable posture of robot = (22.35 cm) if θ* = 90o, • the terrain is flat, • the legs are not allowed to collide or overlap, and • the horizontal workspace of hexapod leg is the reachable areas include the sections in the xy plane around the individual coxas, y-plane = 24.25 cm and within the mechanical joint limits but in this case limit joint (half range of coxa angle is taken in order not to the legs collide) so the range is "−45 < θ� < 45$ degree. another approach for constrained workspace is derived, the more details in [12], [13]. for the hexagonal model the mathematically eq. 13 for the radius of the annulus is : r���) = "r��d + q$) + f�) ∗ ph) … (13) where: r��� , r��d, q, p defined by figure 5. fig. 5. the relationship between the reachable area and annuls. and the rectangular area is the reachable area of each leg of robot, for our hexapod robot rmax = (10.5 cm) from coxa joint. added the length of center robot (13.75 cm), rmax = (24.25 cm). the center of leg tip point is (22.35 cm) that it is equal to the posture robot in method1 above comparing between two constraints workspaces methods are found that the maximum reaches of the leg are equal for our hexapod robot. 4. modified classical stability margins analysis approach of hexapod robot the first gait of the hexapod robot is the tripod gait. in this gait the three legs stay on the ground (support pattern) while the other legs are on the air. the analysis of static stability depended on the eq. 14 (the triple equation in the figure 6) [14] that only computes the s1 where s2 and s3 are evaluated from the same pervious equation but with changing the coordinates of legs for each s1, s2 as in the figure 6 of three triangles and there are two conditions to set the robot stable first if s1, s2 and s3 are >= zero, the tripod is considered stable other, the tripod is considered unstable more details in [14]. from the definition of “stability margin,” (sm), is the shortest distance from the vertical projection of the center of robot to the boundaries of the support pattern in the horizontal plane [15] the proposed method is explained below: in figure 6 l1 is derived in the eq. 16 (the distance line between two points) and the same thing of l2 is computed, l3 for other legs, each l is considered as a base of the one triangle while the areas of the s1, s2 and s3 are previously computed so that the stability margin is the shortest perpendicular distances from l1, l2 and l3 to the center of robot (h1, h2, h3 respectively). h1 is computed as eq. 17 as well as the h2, h3 are computed in the same manner. the stability margins are computed and analyzed for all cases of the hexapod legs motion for three gaits (tripod, ripple and wave) for example the support pattern of tripod when robot lifts legs (1, 3 and 5) : fig. 6. the stability analysis for the tripod gait when legs (2, 6 and 4) on the ground and legs (1, 3 and 5) on the air. the triple equation of the figure 6 is: s� = �) j 1 1 1xkl xm x)ykl ym y)j . . . "14$ the support pattern cb l1 l2 l3 s1 s2 s3 leg 2 leg 6 leg 4 h1 h3 h2 firas a. raheem al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 4459 (2015) 49 where (xkl, ykl) the coordinate of center body, (x), y)) the coordinate of leg 2, (xm, ym) the coordinate of leg 4. the simplification of the eq. 14 : s� = �) o"xm − xkl$"y) − ykl$ − "x) −xkl$p"ym − ykl$qr … "15$ l� = sqrt ""x) − xm$) + "y) − ym$)$ … "16$ where l1 is the distance between two points h� = 2 ∗ 0s�l�1 … "17$ from figure 6 the stability margin are computed as: sm� = min"h� , h), h*$ … "18$ sm� is the stability margin of the support pattern of legs (2, 4 and 6) similarly, the sm) is derived for other three legs when (1, 3 and 5). besides that, eq. 18 is derived for the other gaits of robot (wave and ripple). 5. walking, mechanism of leg motion and path planning of hexapod robot the mechanism of leg motion is very complex problem that each leg is forward and back motion. it derived from insect motion that has two phases: swing (the leg in the air) and stance (the leg in the ground) phases [3]. the equations of motion in [16] are derived for two phases. the walking of hexapod robot is developed by combing the stance phase [16] explained by eq. 19 and the swing phase [17] as in eq. 20 to get our modified smooth gait for one hexapod’s leg as below: x�w� = x� − v ∗ t ∗ cos"ϕ$, y�w� = y� − v ∗ t ∗ sin"ϕ$ …(19) where x�, y� the coordinates of leg tip derived from the forward kinematic, ϕ is the direction of motion, t is the period required to complete one cycle and changes during type gait and v describes how many centimeters per gait cycle the hexapod robot should move. the equations in swing phase are: x�w� = 2 ∗ xz[ ∗ dt� �\"1 − cos 0 ] ^ _`ab1$, y�w� = 2 ∗ yz[ ∗ dt� �\"1 − cos 0 ] ^ _`ab1$, z�w� = h ∗ "1 − cos 0 ] ^ _`ab1$ …(20) xz[ , yz[ are the speed of the hexapod robot’s truck in x and y directions, dt� �\ is the time duration for each step and h is the height of each step. the movement of the center of body that moves from start point to the goal point so the new center point [14] is calculated as: x��w� = x�� + d ∗ cos"ϕ$, y��w� = y�� + d ∗ sin"ϕ$ …(21) where d is the step size. the path planning start from point (0,0) cm and end with goal point (500,0)cm for the straight line. 6. stability margins enhancement using genetic algorithm the results of sequences of three main gaits for hexapod robot are found the range values for the stability margins as mentioned above. each gait of hexapod robot, has the sequence of gait such as the tripod gait has two sequences, the first sequence lifts legs (1, 3 and 5) where the legs (2, 4 and 6) on the ground. the second sequence lifts legs (2, 4 and 6) where the legs (1, 3 and 5) are on the ground. in the proposed method, an intelligent method which is (ga) has been applied to find the best stability margin during each sequence in each gait. while modified classical stability margins analysis method which used to find the range values for stability margins is considered as constraints for genetic algorithm to find the best stability margins based on these constraints. also, the genetic algorithm has been applied to find the best positions of legs tips as described below: a. parameters initialization of genetic algorithm the initial populations for genetic algorithm are the coordinates of each leg’s tip (xi, yi) and the coordinates of center body (xcbi, ycbi) while the (zi) is constant (the motion of hexapod robot on the flat plane). chromosomes (individuals) represent the solutions for optimization problem. in the proposed work, the better results of new stable population are evaluated. these results are considered as initial coordinate (xi, yi) for walking of the hexapod robot. these stable positions are repeated till hexapod robot reaches to the goal point. the size of genes in each chromosome is various according to the type of gait (support pattern for each sequence) for example the size of firas a. raheem al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 4459 (2015) 50 chromosomes equals to eight variables in tripod gait. the first sequence in tripod gait when lifting legs (1, 3 and 5) where legs (2, 4 and 6) on the ground have been calculated with center body coordinates as the following formula: chromosome = gx� y� x) y) xh yh xm ymi. the other sequences of hexapod gaits types are formulated as in the above example and according to each gait. b. fitness function: the fitness function of ga is used as minimization of the cost function (stability margins) as derived previously, where each sm =min"h�, h), … , hh$ and the hi defined in section (4). for example ,the fitness function of tripod gait equals to stability margin (sm) is selected according to the each sequence of each gait such as the eq. 18 the idea of proposed approach is different from the approach in [17]. the difference is that the researchers in [17] that the minimum fitness stability margin is squared value (fitness function =sm2) in order to get the high values of stability margin (sm), while in proposed work, the minimum fitness stability margin is (fitness function =sm) and all values are high and within the constraints of legs tips without need to square the stability margin (sm). all cases of our approach results of the stability margin are within the ranges of stability margins from modified classical analysis method. in the ga, the best stability margins are evaluated while in the modified classical approach the ranges of the stability margins are obtained. the all cases of the fitness equations for three gaits are derived from the modified classical stability method where in each sequence there is fitness function as an example for eq. 18 is the fitness function of tripod gait for the first sequence (where the robot lifting legs (1, 3 and 5) and legs (2, 4 and 6) are on the ground). c. crossover operation the main processing of crossover is to get two parents of coordinates of leg’s tips and the center body coordinates and producing from them the children. crossover operator is applied to produce a better offspring (children). d. mutation operation after the crossover operation, the output string from crossover is subjected to mutation process. fig. 7. proposed flowchart of ga. 7. flowchart of proposed genetic algorithm after complete the modified classical method, below will describe the developed method using genetic algorithm. in the figure 7 shows that flowchart of proposed genetic algorithm. it has consists of steps where described as below: • defined the variables which determined the leg’s tip of hexapod robot (chromosomes). • generate the coordinates of leg’s tip and center point of body (chromosomes). • find the cost function (stability margins equations as in section (4) to get the best stability margin for each sequence for each gait. • select mates, mating, and mutation. • convergences condition, if the generation <= ng (100 generations). • done. 8. simulation results the simulation results consist of two approaches where illustrated as below: firas a. raheem al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 4459 (2015) 51 8.1. the modified classical stability margins analysis of the stability margins above for three gaits (ripple, wave and tripod) are simulated for each gait within the steps as below: athe wave gait cases 1 2 3 4 5 6 fig. 8. the configuration of hexapod robot’s leg of sequences of wave gait. firas a. raheem al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 4459 (2015) 52 bthe ripple gait cases 1 2 3 4 fig. 9. the configuration of hexapod robot’s leg of sequences of ripple gait. cthe tripod gait cases 1 2 fig. 10. the configuration of hexapod robot’s leg of sequences of tripod gait. the figures (8-10) show that the configurations of hexapod robot’s legs for three gaits. the yellow lines indicated to the support patterns. from support patterns the (sm) is evaluated for each sequence in every gait and the simulation results of all stability margins are described in simulations below: firas a. raheem al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 4459 (2015) 53 (a) (b) firas a. raheem al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 4459 (2015) 54 (c) fig. 11. minimum and maximum stability margins for, (a) ripple gait, (b) tripod gait, and (c) wave gait. in figure 11 shows that the stable range of stability margins for three gaits and these values are considered the constraints to the genetic algorithm of our proposed work. 8.2. best stability margins using genetic algorithm from the study in the section (4), the results of best stability margins are shown in below: fig. 12. the best fitness value for tripod gait when the legs (2, 6, and 4) are on the ground and lifting legs (1, 3 and 5). fig. 13. the best fitness value for tripod gait when the legs (1, 3 and 5) are on the ground and lifting legs (2, 6 and 4). 0 10 20 30 40 50 60 70 80 90 100 3.935 3.936 3.937 3.938 3.939 generation f itn es s va lu e best fitness: 3.9356 average distance between individuals best f itness 0 10 20 30 40 50 60 70 80 90 100 5.1 5.2 5.3 5.4 generation f itn es s va lu e best fitness: 5.1304 average distance between individuals best fitness firas a. raheem al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 4459 (2015) 55 fig. 14. the best fitness value for ripple gait when the legs (2, 3, 5, and 4) are on the ground and lifting legs (1, and 6). fig. 15. the best fitness value for ripple gait when the legs (4, 1, 2, 3 and 6) on the ground and lifting leg (5). fig. 16. best fitness value for ripple gait when the legs (1,2,3,6 and 5) on the ground and lifting leg (3 and 4). fig. 17. the best fitness value for ripple gait when the legs (1, 3, 6, 5 and 4) on the ground and lifting leg (2). fig. 18. the best fitness value for wave gait when the legs (2, 3, 6, 5 and 4) on the ground and lifting leg (1). fig. 19. the best fitness value for wave gait when the legs (1, 3, 6, 5 and 4) on the ground and lifting (2). 0 10 20 30 40 50 60 70 80 90 100 6.26 6.265 6.27 6.275 6.28 generation f itn es s va lu e best fitness: 6.2614 best f itness 0 10 20 30 40 50 60 70 80 90 100 12 13 14 15 generation f itn es s va lu e best fitness: 13.1925 average distance between individuals best fitness 0 10 20 30 40 50 60 70 80 90 100 8.48 8.5 8.52 8.54 generation f itn es s va lu e best fitness: 8.4736 best f itness 0 10 20 30 40 50 60 70 80 90 100 12.55 12.6 12.65 12.7 12.75 generation f itn es s va lu e best fitness: 12.5673 best fitness 0 10 20 30 40 50 60 70 80 90 100 6.6 6.62 6.64 6.66 generation f itn es s va lu e best fitness: 6.6121 best fitness 0 10 20 30 40 50 60 70 80 90 100 13.98 13.99 14 14.01 14.02 generation f itn es s va lu e best fitness: 13.9895 average distance between individuals best f itness firas a. raheem al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 4459 (2015) 56 fig. 20. the best fitness value for wave gait when the legs (1, 2, 6, 5 and 4) on the ground and lifting leg (3). fig. 21. the best fitness value for wave gait when the legs (1, 2, 3, 6 and 5) on the ground and lifting leg (4). fig. 22. the best fitness value for wave gait when the legs (1, 2, 3, 6 and 4) on the ground and lifting leg (5). fig. 23. the best fitness value for wave gait when the legs (1, 2, 3, 5 and 4) on the ground and lifting leg (6). the above figures (12 23) show that the best stability margins for each sequence in each gait and all the stability margins are within the range of constraints that described in classical stability margins analyses method. the analysis equations of eq. 21 used of find the next points of the hexapod center body and the errors center body of the path planning for two approaches is shown in table 2, below: table 2, shows that the errors of two approaches modified classical stability margins and stability margins enhanement using ga. errors path planning of modified classical stability margins errors path planning of stability margins enhancement using ga 1tripod gait has less error value equals (8.3630e-004) cm. 2wave gait has less error value equals (0.0023) cm. 3ripple gait has great error value equals (0.0520) cm. 1tripod gait has less error value equals (2.3590e-004) cm. 2wave gait has error value equals (0.0012) cm. 3ripple gait has great error value equals (0.0196) cm. the genetic algorithm here works as off-line and getting the new stable coordinates of legs tips of hexapod robot (new populations) before robot start walking .from these coordinates are selected, the best points of the center body in (x , y) plane are calculated according to the best stability margins values. 0 10 20 30 40 50 60 70 80 90 100 5.46 5.48 5.5 5.52 generation f itn es s va lu e best fitness: 5.4661 average distance between individuals best f itness 0 10 20 30 40 50 60 70 80 90 100 12.69 12.695 12.7 12.705 12.71 generation f itn es s va lu e best fitness: 12.6927 best fitness 0 10 20 30 40 50 60 70 80 90 100 6.8 6.9 7 7.1 7.2 7.3 generation f itn es s va lu e best fitness: 6.883 best fitness 0 10 20 30 40 50 60 70 80 90 100 7.5 7.6 7.7 7.8 generation f itn es s va lu e best fitness: 7.5258 best f itness firas a. raheem al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 4459 (2015) 57 9. conclusion in this paper the stability margins are analyzed for all gaits of hexapod robot in two approaches first is the modified classical approach and second, is the stability margins enhancement using genetic algorithm. in first approach, the range of stability margins values are evaluated for each sequence in every gait where the hexapod walking from start point (0,0) cm to the goal point (500,0) cm. for the second approach, the best stability margins for each sequence in every gait are calculated and the results is useful to get best stable path planning with smaller error than the first approach for three gaits of hexapod robot as in table 2, above .also in the second approach and according to the best stability margins values. the better new stable coordinates (positions of legs) are gotten than stable coordinates of first approach. in addition, the better new stable center body coordinates are evaluated than center body coordinates in the first approach notation di translation along zi-1 axis a� = li link length about xi-1 axis t���� forward kinematic matrix x, y, z coordinates of hexapod's leg r��� maximum length of leg's workspace r��d minimum length of leg's workspace q, p lengths of rectangular reachable area s� triple equation h� vertical line from the center point of the robot’s body to the middle of the base (l1) sm stability margin x�w�, y�w� backward smooth motion x�w�, y�w�,z�w� forward smooth motion ϕ direction of motion t period required to complete one cycle d step size xz[ ,yz[ are the speed of the hexapod robot’s truck in x and y directions dt� �\ time duration for each step h height of each step x��w� , y��w� new center coordinates of hexapod's body xcbi, ycbi center coordinates of hexapod's body v represents speed of how centimeter per gait cycle the robot should move ga genetic algorithm greek letters θ� rotation angle about zi-1 axis α� rotation angle about xi-1 axis φ� angle between the x-axis and line a 10. references [1] x. ding, z. wang, a. rovetta and j.m. zhu, “locomotion analysis of hexapod robot, climbing and walking robots,” behnam miripour (ed.), 2010. [2] m. i. ahmad, d. k. biswas and s. s roy, “gait analysis of eight legged robot,” international journal of mechanical and industrial engineering (ijmie), issn no. 2231 – 6477, vol. 2, issue-2, 2012. [3] b. j., “biologically inspired approaches for locomotion, anomaly detection and reconfiguration for walking robots,” springer-verlag berlin heidelberg, 2011. [4] d. a. bucur, s. a. dumitru, “genetic algorithm for walking robots motion optimization,” institute of solid mechanics of the romanian academy 15 c-tin mille, sector 1, bucharest, romania, 2011. [5] j. currie, m. beckerleg, j. collins, “software evolution of a hexapod robot walking,” 15th international conference on mechatronics and machine vision in practice (m2vip08), 2008. [6] b.l. luk, s. galt and s. chen, “using genetic algorithms to establish efficient walking gaits for an eight-legged robot,”, 2001. [7] k. w., d.b. and a. k., “control and environment sensing system for a six-legged robot,”, journal of automation, mobile robotics & intelligent systems, vol. 2, no. 3, 2008. [8] j. barreto, a. trigo, p. menezes, dias j., “kinematic and dynamic modeling of a six legged robot,” citeseer, 2004. [9] m. o. sorin, n. mircea, “matlab simulator for gravitational stability analysis of a hexapod robot,” the romanian review precision mechanics, optics & mechatronics, 158, no. 39 mechanics, optics & mechatronics, 2011. firas a. raheem al-khwarizmi engineering journal, vol. 11, no. 4, p.p. 4459 (2015) 58 [10] http://www.lynxmotion.com/c-100-bh3r.aspx, accessed on 17/11/2013. [11] s. r. j., “fundamentals of robotics: analysis and control”, isbn: 0-13-344433-3, prentice hall, new jersey, usa, 1990. [12] r. b. mcghee and g. i. iswandhi, “adaptive locomotion of a multilegged robot over rough terrain,” ieee trans. syst., man, cybern., vol. smc-9, no. 4, pp. 176–182, 1979. [13] stanley kwok-kei chu and grantham kwok-hung pang, “comparison between different model of hexapod robot in faulttolerant gait,” ieee trans. syst. man cybern,—part a: system and humans, vol. 32, no. 6, november, 2002. [14] charles andrew schue, “simulation of tripod gaits for a hexapod underwater walking machine,” master’s thesis, naval postgraduate school monterey, california, june, 1993. [15] s. m. song and b. s. choi, “the optimally stable ranges of 2n-legged wave gaits,” ieee trans. on system, man, and cybernetics, vol. 20, no. 4, jul./aug., 1990. [16] s. villumsen, “modeling and control of a six legged mobile robot,” master thesis, 2010. [17] m. a. shahriari, k. g. osguie, a. a. akbar khayyat, “modular framework kinematic and fuzzy reward reinforcement learning analysis of a radially symmetric sixlegged robot,” life science journal, 2013. radially symmetric six-legged robot,” life science journal, 2013. )2015( 4459، 456' 4، ا"2*د11*%$' ا"0/ارز#ا",+*()' ا"&%$# ا"!زاق �راس ��د 59 �ار�� ا������ ��������د رو��ت ������ام ا���ارز��� ا���������� ! ��� ا �اس &%� ا��زاق ر#�" ( ** )��* �ھ�� زھ� * ا"ab+/"/@)'ا"%?#2' / <>7 ھ+*(' ا">);!ة وا"+78 **،* dr.firas7010@yahoo.com -cو!ba"dا *e!f"ا: * hhindzuhair@yahoo.com -cو!ba"dا *e!f"ا: ** ا��-,� . 5c>,? ا",h?<a/د روh/ت qfoe ا"o4!ة "q" .?,r?s!t q" u"v ا"p*رة m$n ا"&m$n -o اdرض. ار@k ذو (b'ھ/ روh/ت #)a(c?a#!ن ھh?<a/د روh/ت و "ks -] ^h?x kao 'xyx mpfr _pe d -a اdو<?ت "s!4$?ت ا",h?<a/د روh/ت b4e?ج "$pf?ء #>pb!ا r .h&/ج#b&/@' و ، ا"p/ام 'xyx)ھvه ا"s!4?ت ھ اn -#?#d$7 ا"s!4'[ھvه ا"/ر<' 7r اpbc?ق ). mn*r )stability marginاpb)d!ارe' ا"bh?a' اb<# . -o&$" '+#d&!ةأر@k او اm$n !as اdرض h`/رة qr?s!t و7r اpbc?ق #2?دdت ر(7 وmatlab r2010a u"vsا",h?<a/د روh/ت e#?c!fh #/دke وا"ka" -5$0 (?ق [ا",h?<a/د روh/ت "d!ض ر(7 t?<# ت? '(n!5"ا k&2"قا?) ka" ون .ا"&4*دة*h 4!كbr k@رdا ?#*+n 4*ثr ?,c?h ?,5e!2r ha&# '(n!5"ا k&2"ت ا?t?<# م/%tا u"vsو ?,i2h _# 6;*ام m$n k&2r's!t ka" ط/p<"ا h# ?,2+&h ة!pb<# k@رdا k5t .k($4r 7r h(<4rو 's!4"ا '&n?+"اl@رmb"وط/ر ا n>/b"ط/ر ا heا";/ر ya". t 7r>?ب #%&/h# 'n ، ھvه ا";!stability margins ( .]'pe( ا"&k" '"*2 اdو"m ا";!pe' ا"a()ya)'، ا"m$n p(s!b ط!r 7h(bpe[ا"k&2 ا"&bp!ح h?(0b*ام ا"0/ارز#)' ا"%)+)' ا"t -b>+^ اd(pb!ارe' ا"stability margins 'bh?aا";!pe' ا"c?a)' (&)^ ب . "ka ا"s!4?ت ) stability margins(<)7 ال k" 7(> ki]ا m$n ?,"/`4hstability margins 5)*ة [ا"4`/ل# es?b+"ه اvت وھ/hد رو/h?<a,$" h# k>ا m;0h 's!4$" -;t ر?<# ki]ا m$n k@رdت ا?e?,+" ة*e*@ ة!pb<# ت?(xا*tا m$n 7 ا"4`/لr *> و m"وdا 'pe!;"ا m"وdا 'pe!;"ا h# ki]ا .u"ذ m"ا ']?uyh ، ^c?s '(c?a"ا 'pe!;"ا -] m"وdا 'pe!;"ا h# ki]ت ا/h7 ا"!و<@ ps!# ت?(xا*tا. al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 1120 (2014) experimental modeling and optimization of fatigue life and hardness of carbon steel ck35 under dynamic buckling ahmed naif al-khazraji department of mechanical engineering / university of technology e-mail: dr_ahmed53@yahoo.com (received 24 march 2014; accepted 22 june 2014) abstract the aim of this paper is to model and optimize the fatigue life and hardness of medium carbon steel ck35 subjected to dynamic buckling. different ranges of shot peening time (stp) and critical points of slenderness ratio which is between the long and intermediate columns, as input factors, were used to obtain their influences on the fatigue life and hardness, as main responses. experimental measurements of shot peening time and buckling were taken and analyzed using (design expert 8) experimental design software which was used for modeling and optimization purposes. mathematical models of responses were obtained and analyzed by anova variance to verify the adequacy of the models. the resultant quadratic models were obtained. a good agreement was found between the results of these models and optimization with the experimental ones with confidence level of 95 %. keywords: buckling; fatigue life, hardness, shot peening, modeling, optimization. 1. introduction the yielding is a phenomenon of failure of a material under different statical and dynamic loads, this is a fact for short members or bars. but if a bar is long (strut), the failure become a buckling phenomenon or elastic instability. the strut (column) buckled at a certain critical load (pcr.) and then collapsed suddenly [1]. thus, a column fails by buckling at load lower than the yield load. the objective of column analysis methods is to estimate the load or stress at, which a column would become unstable and buckle [1]. surface treatments of shot peening on steel have been extensively used in the automotive, aerospace and petro-chemical fields. shot peening is an effective way of surface treatment in engineering components widely used creation compressive residual stresses and improving the strength to buckling failure, corrosion, fatigue and fatigue-creep interaction [3,4]. this paper investigates the effect of different shot peening time (spt) under the variant combined loads to get mathematical models of optimum fatigue life and hardness based on experimental results. different soft computing techniques are widely used to improve the predicting and optimization capability [5], and various statistical tools have been applied for the modeling and optimization purposes [6], such as using the design of experiment (doe) with the response surface methodology (rsm). the objective of the doe is to optimize a response (output variable) which is influenced by several independent variables (input variables). an experiment consists of a series of tests, called runs, in which changes are made in the input variables in order to identify the reason for changes in the output response. rsm has been extensively used in various engineering applications and fields. it is a collection of mathematical and statistical techniques that are used for empirical models building and analysis of problems, in which a response of interest is influenced by several variables, the objective is to optimize this response [7]. due to the little work carried out to model and optimize the fatigue life and hardness of medium mailto:dr_ahmed53@yahoo.com ahmed naif al-khazraji al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 1120 (2014) 12 carbon steel ck35 under dynamic buckling by using doe to determine the effect of the input parameters (shot peening time and critical slenderness ratio) on the behavior of these responses, therefore this paper aims to investigate the influence of using different shot peening times (spt) and critical slenderness ratios under constant combined stresses (compression and bending) which was (222mpa) to get mathematical models of optimum fatigue life and hardness based on experimental results by using the design expert version 8 software with rsm technique and anova variance for statistical analysis, prediction, optimization and comparison purposes. 2. experimental work the material used in this work was a medium carbon steel ck35. this alloy is widely used in many manufacturing and engineering applications; some typical examples are in the manufacture of connecting rods and railway couplings. during preparation the experimental specimens, carful control was performed to produce a good surface finish to minimize the tensile residual stresses at the surface. the received ck35 was a rod of (3 m length and 12 mm diameter). table 1 and table 2 show the chemical composition and mechanical properties of ck35, respectively which were experimented at room temperature. the specimens were prepared for buckling test with different slenderness ratios (s.r = le/r). it was designed to use these different slenderness ratios (s.r) to classify the intermediate and long buckling columns behavior subjected to variant loading. the values of fatigue life for the buckled specimens (columns) were determined by buckling test using the buckling testing machine type (wekop-taiie), while the values of hardness were obtained for different shot peening times using the hardness testing machine. the input parameters used in the whole experimentation procedure were selected according to the practical experience and the limitations of the experimental measurements taken in the present work. these factors are given in table 3 with two levels. the experimental design was the response surface methodology using a central composite rotatable design for 2² factors, with 5 central points and α = ± 2. 13 runs were performed according to the experimental design matrix (5 center points). the runs were performed at random using the order listed in table 4. each parameter was used a different code levels of -2, -1, 0, +1, +2, whereby each level used conformed to an actual value equivalent to the coded value. thus, the input parameters studied are shot peening time and slenderness ratio. the experimental design matrix used for input parameters in terms of actual factors with the experimental values of fatigue life and hardness is given in table 5. the software design expert 8 was used to develop the model. results of test runs are reported as well as the prediction model produced within a 95% confidence interval. 3. results and discussion 3.1. modeling of fatigue life the obtained average response for fatigue life was used in calculating the model of the response surface using the least-squares method. for fatigue life, a quadratic model in coded terms was analyzed with drawbacks elimination of insignificant coefficients at an exit threshold of alpha = 0.1. some coefficients were removed from model in order to obtain a formula with actual factors rather than coded ones. the terms removed were a²b and ab², while the terms a, b, ab, a² and b² had significant effect on fatigue life. table 6 shows the statistical analysis of variance produced by the software for the remaining terms. the model is significant at 95% confidence. it is noted that the shot peening time a),critical slenderness ratio (b), their interaction (ab) and their squares (a² and b²) are all significant terms. the lack of fit test indicates a good model. this models illustrates that only five terms (a, b, ab, a 2 and b 2 ) have the highest impact on fatigue strength. the final equation in terms of coded factors is: 𝐹𝑎𝑡𝑖𝑔𝑢𝑒 𝑙𝑖𝑓𝑒 = + 297.00 + 24.42 ∗ + 1.75 ∗ 𝐵 + 3.75 ∗ 𝐴 ∗ 𝐵 − 9.69 ∗ 𝐴2 + 3.44 ∗ 𝐵2 …(1) final equation in terms of actual factors: 𝐹𝑎𝑡𝑖𝑔𝑢𝑒 𝑙𝑖𝑓𝑒 = + 15374.77778 − 22.52222 ∗ 𝑆𝑕𝑜𝑡 𝑝𝑒𝑒𝑛𝑖𝑛𝑔 𝑡𝑖𝑚𝑒 − 304.94444 ∗ 𝑆𝑙𝑒𝑛𝑑𝑒𝑟𝑛𝑒𝑠𝑠 𝐹𝑎𝑐𝑡𝑜𝑟 + 0.33333 ∗ 𝑆𝑕𝑜𝑡 𝑝𝑒𝑒𝑛𝑖𝑛𝑔 𝑡𝑖𝑚𝑒 ∗ 𝑆𝑙𝑒𝑛𝑑𝑒𝑟𝑛𝑒𝑠𝑠 𝑓𝑎𝑐𝑡𝑜𝑟 − 0.17222 ∗ 𝑆𝑕𝑜𝑡 𝑝𝑒𝑒𝑛𝑖𝑛𝑔 𝑡𝑖𝑚𝑒2 + 1.52778 ∗ 𝑆𝑙𝑒𝑛𝑑𝑒𝑟𝑛𝑒𝑠𝑠 𝑓𝑎𝑐𝑡𝑜𝑟2 . . . 2 to check the adequacy of the model, the following diagnostic plots have to be inspected. looking at the normal probability plot (fig. 1) or ahmed naif al-khazraji al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 1120 (2014) 13 the fatigue life data, the residuals generally that falling on a straight line implying errors, are normally distributed. also, according to fig. 2 that depicts the residuals versus predicted responses for fatigue life data, it is seen that no obvious patterns or unusual structure, implying models accurate. figure 3 reveals that the contour graph of fatigue life as a response, and only the two factor interaction is shown. it is seen that the increase in both shot peening time and slenderness ratio leads to increase the fatigue life. this is most likely due to increasing the compressive residual stresses on the surface. but, at lower values of these parameters, this effect will be less influential. figure 4 manifests the predicted fatigue life data versus the actual ones for comparison purpose. while fig. 5 shows the 3d graph of fatigue life as a function of shot peening time and slenderness ratio. it can be noted that the increase of shot peening time results in an increase in the fatigue life value, while the increase in the slenderness ratio has no effect. therefore, it can be concluded the shot peening time has the highest impact on the fatigue life values at lower and higher slenderness ratios, whereas the slenderness ratio has no significant influence at lower and higher shot peening times. 3.2. modeling of hardness for hardness measurements, a reduced quadratic model in coded terms was analyzed with backwards elimination of insignificant coefficients at the exit threshold of alpha = 0.1. the terms removed were ab, b², a²b and ab², the term b² was reinserted to the hierarchy of the model. this means that the interaction of shot peening time and slenderness ratio had no significant effect on hardness. therefore, only shot peening time (a), slenderness ratio (b) and the squared shot peening time (a²) are significant model terms, and this model indicates that these three terms have a great impact on hardness, as shown in table 7 for the statistical analysis of variance (anova) produced by the software for the remaining terms. the model is significant at 95% confidence. the lack of fit test indicates a good model. the final equation in terms of coded factors is: 𝐻𝑎𝑟𝑑𝑛𝑒𝑠𝑠 = + 24.28 + 1.33 ∗ 𝐴 − 0.50 ∗ 𝐵 − 1.17 ∗ 𝐴2 − 0.30 ∗ b2 …(3) and, the final equation in terms of coded factors is: 𝐻𝑎𝑟𝑑𝑛𝑒𝑠𝑠 = − 1215.22989 + 1.00996 ∗ 𝑆𝑕𝑜𝑡 𝑝𝑒𝑒𝑛𝑖𝑛𝑔 𝑡𝑖𝑚𝑒 + 25.38697 ∗ 𝑆𝑙𝑒𝑛𝑑𝑒𝑟𝑛𝑒𝑠𝑠 𝑓𝑎𝑐𝑡𝑜𝑟 − 0.020805 ∗ 𝑆𝑕𝑜𝑡 𝑝𝑒𝑒𝑛𝑖𝑛𝑔 𝑡𝑖𝑚𝑒2 − 0.13123 ∗ 𝑆𝑙𝑒𝑛𝑑𝑒𝑟𝑛𝑒𝑠𝑠 𝑓𝑎𝑐𝑡𝑜𝑟2 … 4 figure 6 exhibits the normal probability plot of residuals for hardness data, and it can be seen that the residuals (errors) fall generally on a straight line, and they are normally distributed. and, fig. 7 illustrates that no obvious patterns or unusual structure, implying models are accurate. referring to fig. 8 for the contour graph the interaction of shot peening time and slenderness ratio, it can be noticed that the hardness increases with increasing the shot peening time and decreasing the slenderness ratio. this is attributed to increasing the compressive residual stresses and intermediate columns. figure 9 depicts the predicted versus actual hardness data. whereas, fig. 10 reveals the 3d graph of hardness as a function of shot peening time and slenderness ratio. it can be noted that the increase of shot peening time resulted in a higher increase in the hardness value, while the increase in the slenderness ratio has generally a very little effect about 3 % on the hardness at higher shot peening times, since the hardness value decreased slightly with the increase of slenderness ratio. in other words, the shot peening time is more significant than the slenderness ratio in the hardness model. therefore, it can be concluded that the shot peening time has the highest impact on the hardness values at lower and higher slenderness ratios, whereas the slenderness ratio has, in general, no significant influence on the hardness at lower and higher shot peening times. 3.3. optimization of fatigue life and hardness the numerical optimization was provided by the design of experiment software to find out the optimum combinations of parameters in order to fulfill the requirements as desired. therefore, this software was used for this optimization, based on the data from the predictive models for two responses, fatigue life and hardness, as a function of two factors: shot peening time and critical slenderness ratio. from the design summary given in table 8 for main factors and responses, it can be seen that both fatigue life and hardness are modeled with a quadratic model. to develop the new predicted models, a new objective function, named desirability which allows to properly combining all the goals, was ahmed naif al-khazraji al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 1120 (2014) 14 evaluated. desirability is an objective function, to be maximized through a numerical optimization, which ranges from zero to one at the goal. adjusting its weight or importance may alter the characteristics of a goal, and the aim of the optimization is to find a good set of conditions that will meet all the goals. usually, the weights are used to establish an evaluation of the goal’s 3d importance when maximizing desirability function; in this work, weights are not changed since the two responses (fatigue life and hardness) have the importance and are not in conflict within each other. the ultimate goal of this optimization was to obtain the maximum response that simultaneously satisfied all the variable properties. table 9 lists the constrains of each variable for numerical optimization of fatigue life and hardness. according to this table, three possible runs fulfilled these specified constrains to obtain the optimum values for fatigue life and hardness, as given in table 10. it can be seen that all the runs gave desirability of 0.937. figure 11 exhibits the bar graph for the dersirability, while fig. 12 illustrates the 2d graph for desirability as a function of shot peening time and slenderness ratio. figure. 13 shows the surface plot for desiability as a function of shot peening time and critical slenderness ratio. figures 14 and 15 depict the optimum values of fatigue life and hardness, respectively. it can be noted from these figures that the desirability reaches the maximum value of 0.937 when the optimum value of fatigue life is 308.333 cycles (fig. 14) and the optimum vaule of hardness is 24.8153 hrc as shown in fig. 15. table 1, chemical compositions of carbon steel ck35 (wt%). p s si mn c ck35 max 0.035 max 0.035 0.15-0.35 0.5-0.8 0.32-0.39 standard (din 50114) 0.013 0.024 0.25 0.75 0.33 experimental table 2, mechanical properties of carbon steel ck35. poisson's ratio(υ) g(gpa) e(gpa) σy(mpa) σu(mpa) ck35 0.3 79 201 ˃ 392 550-700 standard(din 50114) 0.3 80 205 400 660 experimental table 3, levels of input factors used in respective coding. +alpha alpha high level( +1) low level( 1) units factor 35.00 5.00 27.50 12.50 min shot peening time 101.00 95.00 99.5 96.5 ----slenderness ratio table 4, experimental design matrix for coded input factors and actual responses. standard no. run no. type of point shot peening time (min) slendress ratio fatigue life (cycles) hardness (hrc) 1 8 factorial -1.000 -1.000 268 21.8 2 2 factorial 1.000 -1.000 310 26 3 1 factorial -1.000 1.000 263 21 4 12 factorial 1.000 1.000 320 24 5 7 axial -2.000 0.000 320 18 6 11 axial 2.000 0.000 307 21 7 9 axial 0.000 -2.000 307 24 8 5 axial 0.000 2.000 315 22 9 3 center 0.000 0.000 293 24 10 13 center 0.000 0.000 295 25 11 6 center 0.000 0.000 298 25 12 4 center 0.000 0.000 300 23 13 10 center 0.000 0.000 300 24 ahmed naif al-khazraji al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 1120 (2014) 15 table 5, experimental design matrix for actual input factors and responses. standar d no. run no. type of point shot peening time (min) slendress ratio fatigue life (cycles) hardness (hrc) 1 8 factorial 12.50 96.50 268 21.8 2 2 factorial 27.50 96.50 310 26 3 1 factorial 12.50 99.50 263 21 4 12 factorial 27.50 99.50 320 24 5 7 axial 5.00 98.00 320 18 6 11 axial 35.00 98.00 307 21 7 9 axial 20.00 95.00 307 24 8 5 axial 20.00 101.00 315 22 9 3 center 20.00 98.00 293 24 10 13 center 20.00 98.00 295 25 11 6 center 20.00 98.00 298 25 12 4 center 20.00 98.00 300 23 13 10 center 20.00 98.00 300 24 table 6, anova for response surface quadratic model (fatigue life) analysis of variance table [partial sum of squares type iii]. source sum of squares df mean square f value p-value prob > f model 10351.89 5 2070.38 341.67 < 0.0001 significant a-shot peening time 7154.08 1 7154.08 1180.63 < 0.0001 b-slenderness ratio 36.75 1 36.75 6.06 0.0433 ab 56.25 1 56.25 9.28 0.0187 a² 2150.39 1 2150.39 354.88 < 0.0001 b² 270.76 1 270.76 44.68 0.0003 residual 42.42 7 6.06 lack of fit 3.62 3 1.21 0.12 0.9409 not significant pure error 38.80 4 9.70 cor total 10394.31 12 std. dev. 2.46 r-squared 0.9959 mean 291.23 adj r-squared 0.9930 c.v.% 0.85 pred r-squared 0.9915 press 88.59 adeq precision 66.524 ahmed naif al-khazraji al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 1120 (2014) 16 table 7, anova for response surface quadratic model (hardness) analysis of variance table [partial sum of squares type iii] source sum of squares df mean square f value p-value prob > f model 55.75 4 13.94 35.11 < 0.0001 significant a-shot peening time 21.33 1 21.33 53.75 < 0.0001 b-slenderness ratio 3.00 1 3.00 7.56 0.0251 a² 31.38 1 31.38 79.06 < 0.0001 b² 2.00 1 2.00 5.03 0.0551 residual 3.18 8 0.40 lack of fit 0.38 4 0.094 0.13 0.9614 not significant pure error 2.80 4 0.70 cor total 58.92 12 std. dev. 0.63 r-squared 0.9461 mean 22.92 adj r-squared 0.9192 c.v.% 2.75 pred r-squared 0.8870 press 6.66 adeq precision 19.747 table 8, design summary for main factors and responses (design model: quadratic) factors name unit min. max. coded values mean std. dev. a shot peening time min 5.00 35.00 -1.0000=12.50 +1.000=27.00 20.00 7.21 b slenderness ratio ---95.00 101.00 -1.000=96.50 +1.000=99.50 98.00 1.44 response name unit min. max. mean ratio. std. dev. y1 fatigue life cycles 210 320 291.231 1.52381 29.4311 y2 hardness hrc 17 25 22.9231 1.47059 2.21591 table 9, constrains of each varaible for numerical optimization of the fatigue life and hardness. types of variables goal lower limit upper limit lower weight upper weight importance a: shot peening time is in range 12.5 27.5 1 1 3 b: slenderness ratio is in range 96.5 99.5 1 1 3 fatigue life maximize 210 320 1 1 3 hardness maximize 17 25 1 1 3 table 10, optimal conditions used to obtain the maximum fatigue life and hardness. no. shot peening time (min) slenderness ratio fatigue life (cycles) hardness (hrc) desirability 1 25.74 96.50 308.833 24.8153 0.937 selected 2 25.80 96.50 308.876 24.8117 0.937 3 25.54 96.50 308.668 24.8269 0.937 ahmed naif al-khazraji al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 1120 (2014) 17 fig. 1. normal probability plot for fatigue life data. fig. 2. residual versus predicted responses for fatigue life data. fig. 3. contour graph of fatigue life as a function of shot peening time (min) and slenderness ratio. fig. 4.predicted versus actual fatigue life data for comparison. fig. 5. 3d graph of fatigue life as a function of shot peening time (min) and slenderness ratio. fig. 6. normal probability plot for hardness data. design-expert® software fatigue life color points by value of fatigue life: 320 210 internally studentized residuals n o rm a l % p ro b a b il it y normal plot of residuals -2.00 -1.00 0.00 1.00 2.00 1 5 10 20 30 50 70 80 90 95 99 design-expert® software fatigue life color points by value of fatigue life: 320 210 2 predicted in te rn a ll y s tu d e n ti z e d r e s id u a ls residuals vs. predicted -3.00 -2.00 -1.00 0.00 1.00 2.00 3.00 200.00 220.00 240.00 260.00 280.00 300.00 320.00 340.00 design-expert® software factor coding: actual fatigue life design points 320 210 x1 = a: shot peening time x2 = b: slenderness factor 12.50 15.50 18.50 21.50 24.50 27.50 96.50 97.10 97.70 98.30 98.90 99.50 fatigue life a: shot peening time b : s le n d e rn e s s f a c to r 270 275 280 285 290 295 300 305 310 315 5 design-expert® software fatigue life color points by value of fatigue life: 320 210 2 actual p re d ic te d predicted vs. actual 200.00 220.00 240.00 260.00 280.00 300.00 320.00 340.00 200.00 220.00 240.00 260.00 280.00 300.00 320.00 design-expert® software factor coding: actual fatigue life design points above predicted value design points below predicted value 320 210 x1 = a: shot peening time x2 = b: slenderness factor 96.50 97.10 97.70 98.30 98.90 99.50 12.50 15.50 18.50 21.50 24.50 27.50 260 270 280 290 300 310 320 330 f a ti g u e l if e a: shot peening time b: slenderness factor design-expert® software hardness color points by value of hardness: 25 17 internally studentized residuals n o r m a l % p r o b a b il it y normal plot of residuals -3.00 -2.00 -1.00 0.00 1.00 2.00 1 5 10 20 30 50 70 80 90 95 99 ahmed naif al-khazraji al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 1120 (2014) 18 fig. 7. residual versus predicted responses for harness data. fig. 8. contour graph of hardness (hrc) as a function of shot peening time and slenderness ratio. fig. 9. predicted versus actual hardness data for comparison. fig. 10. 3d graph of hardness (hrc) as a function of shot peening time (min) and slenderness ratio. fig. 11. bar graph for the desirability. fig. 12. 2d contour for desirability as a function of shot peening and slenderness ratio. design-expert® software hardness color points by value of hardness: 25 17 2 2 predicted in te r n a ll y s tu d e n ti z e d r e s id u a ls residuals vs. predicted -3.00 -2.00 -1.00 0.00 1.00 2.00 3.00 16.00 18.00 20.00 22.00 24.00 26.00 design-expert® software factor coding: actual hardness design points 25 17 x1 = a: shot peening time x2 = b: slenderness factor 12.50 15.20 17.90 20.60 23.30 26.00 96.50 97.10 97.70 98.30 98.90 99.50 hardness a: shot peening time b : s le n d e r n e s s f a c to r 21.5 22 22.5 23 23.5 24 24.5 5 design-expert® software hardness color points by value of hardness: 25 17 2 2 actual p r e d ic te d predicted vs. actual 16.00 18.00 20.00 22.00 24.00 26.00 16.00 18.00 20.00 22.00 24.00 26.00 design-expert® software factor coding: actual hardness design points above predicted value design points below predicted value 25 17 x1 = a: shot peening time x2 = b: slenderness factor 96.50 97.10 97.70 98.30 98.90 99.50 12.50 15.20 17.90 20.60 23.30 26.00 16 18 20 22 24 26 h a rd n e s s a: shot peening time b: slenderness factor 1 1 0.898486 0.976915 0.93688 desirability 0.000 0.250 0.500 0.750 1.000 a:shot peening time b:slenderness factor fatigue life hardness combined design-expert® software factor coding: actual desirability design points 1 0 x1 = a: shot peening time x2 = b: slenderness factor 12.50 15.50 18.50 21.50 24.50 27.50 96.50 97.10 97.70 98.30 98.90 99.50 desirability a: shot peening time b : s l e n d e r n e s s f a c t o r 0.55 0.6 0.65 0.7 0.75 0.8 0.85 0.9 5 prediction 0.93688 ahmed naif al-khazraji al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 1120 (2014) 19 fig. 13.3d surface plot for desirability as a function of shot peening time and slenderness ratio. fig.14. the optimum value of fatigue life (cycles). fig. 15. the optimum value of hardness (hrc). 4. conclusions 1. quadratic equations for both fatigue life and hardness were developed at 95% confidence. 2. the shot peening time (spt) has a great impact on fatigue life and hardness, while the slenderness ratio has a lower effect with 3 %. 3. based on the response optimization, the optimum value of fatigue is 308.33 cycles and the optimum value of hardness is 24.8153 hrc with desirability reaching maximum value of 0.937. 5. references [1] k. h. al-jubori,"column lateral buckling under combined dynamic loading", phd thesis, university of technology,2005. [2] mott robert l., "applied strength of materials", 3rd. ed., prentice hall, englewood cliffs, new jersy, 1996. [3] [3] caravallo a. l. m., and voorwald, h. j. c., "influence of shot peening and chord chromium electroplating on the fatigue strength of 7050-t7451 aluminum alloy", international journal of fatigue , vol. 29, pp. 1282-1291, 2007. [4] h. j. mohamed al-alkawi and hussain abdul aziz, "an appraisal of euler and johnson buckling theories under dynamic compression buckling loading", the iraqi journal for mechanical and material engineering, vol. 7, no. 2, pp. 108-116, 2007 [5] k. pal and s. k. pal, "soft computing methods used for the modeling and optimization of gas metal arc welding: a review", int. journal of manufacturing research, vol. 6, no.1, pp. 15-29, 2011. [6] samir ali amin and salah sabeeh abedalkareem, "modeling and optimization of gmaw weld geometry (weld bead and penetration) for steel aisi 1025", third scientific international conference, technical education / najaf, 2012. [7] montgomery, d. c., “design and analysis of experiments: response surface method and designs”, new jersey: john wiley and sons, inc., 2005. design-expert® software factor coding: actual desirability 1.000 0.000 x1 = a: shot peening time x2 = b: slenderness factor 96.50 97.10 97.70 98.30 98.90 99.50 12.50 15.50 18.50 21.50 24.50 27.50 0.400 0.500 0.600 0.700 0.800 0.900 1.000 d e s i r a b i l i t y a: shot peening time b: slenderness factor 0.9370.937 design-expert® software factor coding: actual fatigue life design points 320 210 x1 = a: shot peening time x2 = b: slenderness factor 12.50 15.50 18.50 21.50 24.50 27.50 96.50 97.10 97.70 98.30 98.90 99.50 fatigue life a: shot peening time b : s l e n d e r n e s s f a c t o r 270 275 280 285 290 295 300 305 310 315 5 prediction 308.833 design-expert® software factor coding: actual hardness design points 25 17 x1 = a: shot peening time x2 = b: slenderness factor 12.50 15.50 18.50 21.50 24.50 27.50 96.50 97.10 97.70 98.30 98.90 99.50 hardness a: shot peening time b : s l e n d e r n e s s f a c t o r 21.5 22 22.5 23 23.5 24 24.5 5 prediction 24.8153 (2014) 1120، صفحت 4، انعذد10دجهت انخىاسصيي انهنذسيت انًجمو احًذ نايف انخضسجي 20 تحت تأثيش احًال ( ck35) انكاسبىنياننًزجت انعًهيت انًثهى نعًش انتصذع وانصالدة نهفىالر النبعاج انذيناييكيت ا ابشاهيى انخضسجي أحًذ نايف اندايعح انركُهىخيح / قسى هُذسح انًكائٍ وانًعذاخ dr_ahmed53@yahoo.com االنكرشوَي انثشيذ: انخالصت يخرهفح يذياخ اسرخذاو ذى. ديُاييكي اَثعاج عهيها يسهط( ck35) انكاستىٌ يرىسط نهفىالر نصالدجوا انكالل عًشل انًثهً ًَزخحال انً انثحث هزا يهذف وعًش انصالدج عهً ذأثيشاذها إليداد يذخهح عىايمتىصفها وانًرىسطح انطىيهح االعًذج تيٍ كاَد وانري انُحافح نُسة يخرهفح ووقي تانكشاخ انسفع اصيُح يٍ design) انعًهي انرصًيى تشيدح تاسرخذاو وذحهيهها تانكشاخ انسفع ونضيٍ نالَثعاج انعًهيح انقياساخ عهً انحصىل ذى. اسرداتاختىصفها انكالل expert 8 )ذثايٍ تاسرخذاو وذحهيهها نالسرداتاخ انشياضي انحصىل عهً انًىديم ذى. انًثهًانحصىل عهً انًُزخح ألغشاض اسرخذيد وانري (anova )هزِ َرائح تيٍ خيذ ذقاسب وخذ نقذ. تأسرخذاو هار انرثايٍ ذى انحصىل عهً يىديم سياضي يٍ انذسخح انثاَيح. انًُارج صالحيح عهً نهثشهُح %. 95 تًقذاس يىثىقيح يسرىي يع جانعًهيانًُزخح انًثهً وانُرائح mailto:dr_ahmed53@yahoo.com%20البريد mailto:dr_ahmed53@yahoo.com%20البريد (microsoft word 149158 \344\346\321) al-khwarizmi engineering journal,vol. 13, no. 1, p.p. emergency fuel rationing system using rfid smart cards (received 13 september https://doi.org/10.22153/kej.2017.09.004 abstract rationing is a commonly used solution for shortages of country. this paper identifies some common approaches and policies used in rationing as well asrisks suggesta system for rationing fuelwhichcan work efficiently their solutions. the system should theoretically be applicable in emergency situations, to implement at a low cost and minimal changes to infrastructure keywords: rationing, smart-card, authentication, rfid, security, risk management 1. introduction shortages of resources often lead to significant rise in prices even up to 300% governments to interfere and protect by taxes, controlling prices, rationing or discounts [1].a rationing system limits the acquisition commodities equally among citizens that everyone entitled to goods can get their fair share [2]. rationing has been historically used for food, water, energy, and other resources that considered essential. in the past few years, petrol levels declined around the world, most may find themselves in need of rationing system for fuel or risk economical breakdown [2]. 1.1 case studies a. odd-even system: this system has been commonly used in emergency situations in many countries including iraq in recent years, however a well-documented recent and successful example was the 2012 hurricane sandy crisis in the us some pipelines were damaged, 67% of gas stations were compromised in the new york jersey area, then took two weeks to recover. face this emergency, the us deployed the odd khwarizmi engineering journal,vol. 13, no. 1, p.p. 148157 (2017) emergency fuel rationing system using rfid smart cards noor ahmed khudhur email: noorea04@yahoo.com september 2015; accepted 19 september 2016) https://doi.org/10.22153/kej.2017.09.004 rationing is a commonly used solution for shortages of resources and goods that are vital for the citizens of a some common approaches and policies used in rationing as well asrisks can work efficiently. subsequently, addressing all possible security risks and he system should theoretically be applicable in emergency situations, requiring less than three months to implement at a low cost and minimal changes to infrastructure. card, authentication, rfid, security, risk management. shortages of resources often lead to significant up to 300%, leading protect consumers or discounts acquisition of equally among citizens, ensuring get their fair share [2]. rationing has been historically used for and other resources that are in the past few years, petrol most countries rationing systems economical breakdown [2]. this system has been in emergency situations in many countries including iraq in recent years, however t and successful example in the us, as pipelines were damaged, 67% of gas in the new york-new recover. to the us deployed the oddeven system [3]. a similar system had been applied in iraq and other countries during crisis time, using car numbers as a guideline odd numbered plates received fuel numbered days, a car with an plate however, got fuel days of even numbers this system is ideal for emergenc is little time available for employin more substantial, yet, it lacks the ability to deal with complex special cases and prevention of black market activities. b. iran smartcard : the fuel rationing system in iran was introduced in 2007 solution to the constantly rising and to get the country to a more efficient fuel consumption level. this was fixing prices all year long [5][6] was issued a smartcard to distribute rations gas stations were equipped with card reader system would continue to function network is down. counterfeit discovered, are blocked within 24 hours iranian rationing system did effectively reduce fuel utilization and increase the thus it's considered as a successful model, reason for that is the advertising and preparation done before the launch, that allowed understand the system and accept it [7]. al-khwarizmi engineering journal emergency fuel rationing system using rfid smart cards resources and goods that are vital for the citizens of a some common approaches and policies used in rationing as well asrisks that associated to ddressing all possible security risks and requiring less than three months ]. a similar system had been applied in iraq and other countries during crisis as a guideline. cars with fuel rations on odd an even numbered of even numbers. [4]. this system is ideal for emergencies where there is little time available for employing something , it lacks the ability to deal with complex special cases and prevention of the fuel rationing was introduced in 2007, as a constantly rising prices of petrol, more efficient fuel was accomplished by fixing prices all year long [5][6]. every vehicle was issued a smartcard to distribute rations, while stations were equipped with card readers. the system would continue to function even if the counterfeit cards, when blocked within 24 hours. the iranian rationing system did effectively reduce fuel utilization and increase the public awareness, thus it's considered as a successful model, one is the advertising and preparation allowed the public to understand the system and accept it [7]. this noor ahmed khudhur al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 148157(2017) 149 system offers a framework, a look at what a rationing system can accomplish and highlights the importance of advertising to avoid confusion. it is quite similar to the system this paper is aiming to develop; we are looking for a more versatile system that can be deployed within three months in case of emergency. 1.2 . approaches and policies the case studies in this paper, as well as others, such as the world war ii rationing of food or the 1970s petrol crisis in western countries, offer three general models for rationing: a. controlled or fixed pricing: governments can control the supply of goods by regulating prices. a fixed, usually low, price or range of prices is imposed on all suppliers if they want to deal with a particular commodity that is needed this way theoretically ensure equal opportunities, and is commonly used for regulating medicine and healthcare in some countries such as the uk. b. time based :in this model rations are distributed on timely bases, meaning a ration is earned daily, weekly, or monthly. one example of this is the odd-even system mentioned previously, as rations are received every-other-day. another example is the food rationing system employed in iraq and cuba, which is a monthly distribution system. c. quantity based: this model administers the quantities of a certain commodity that a person or a family is allowed, sometimes given free or at reasonable prices making it accessible to everyone. this model is used for essential resources such as food and water, it is often used in poor areas of refugee camps, it was also heavily employed during world war i & ii. these models, on their own, are often used as reaction to a crisis, such as war or natural disasters. a more efficient and regulated system could use two or all three combined to achieve better results. 1.3 techniques for implementation 1.3.1 coupons in the early twentieth century, governments relied on plain paper ids, with signatures, serial numbers and later photographs for identifying individuals [8] thus; early rationing systems utilized paper coupons to identify a citizen’s right to rations. security measures were limited, that included serial numbers and signatures, sometimes with other visual features such as watermarks or deliberate spelling mistakes. 1.3.2 automatic identification with recent technological advancement, automatic identification or auto-id is starting to replace tokens and coupons used previously in rationing systems. there are different identification technologies that need to be studied before determining the most appropriate one for any given situation. table (1) lists commonly used auto-id systems along with a breakdown of their advantages and disadvantages. as we seen from table (1), every technology has its difficulties and advantages; different methods are better suited for different applications. for example, biometrics is often used for high security locations as a means of access control, but rarely in regular public systems where it is too expensive and time consuming. barcodes on the other hand are widely accessible and used regularly by shop owners, but are unsuited for any sort of reliable authentication. the large scope of rationing, and the importance of making the system secure but affordable and accessible at the same time, means we are more likely to consider smartcards or rfid, which are highly secure, commonly used in authentication, and are not complicated or expensive. smartcards are generally considered more secure, but rfid are convenient and faster to read which makes them more ideal for the system as they help reduce long queues. 2. the proposed policy the suggested policy is based on both time and quantity rationing, employing smart rfid cards. it is designed specifically to combat black market and corruption, based on the following guidelines: cardholders are divided into 7 categories, each user group would have a distinct application process, fuel allotment based on their needs and numbers, as well as different guidelines and rules. the cards would have the same design and security features, but differ in color to easily represent the different groups. the 7 categories are shown in table 2. noor ahmed khudhur al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 148157(2017) 150 table 1, commonly used auto-ids (compiled by researcher [9][10][11][12][13]). *some references use the term "smart card" for any type of card with any sort of memory, in this paper it is used to refer more specifically to cards with a memory chip, the technology often used in credit cards. table 2, the seven categories suggested for rationing (the estimated number of cars is, just in example based on latest statistics about cars in iraq [14].) auto -id description advantages disadvantages barcodes a pattern of lines and spaces (squares and spaces in qr barcode) interpreted by a machine to conduct information. • easy to print, with readers commonly available. • inexpensive. • low capacity • lack of resilience and durability. • can be copied or modified easily. ocr: optical character recognition simple plain text that can be interpreted by text recognition software. • the cards require no special technology, traditional printers only. • fast. • complex and unreliable software. • expensive reading devices. • lack of resilience and durability magnetic stripes a card that holds a magnetic tape appearing as a thick black line. • inexpensive. • can be copied or modified easily. • unreliable, prone to failure. • lack of resilience and durability smartcard a card that stores information in a memory, it's contact based, i.e must be inserted into a reading device for authentication • can be designed to prevent unwanted access or alteration. • hard to copy or forge. • readers are expensive and require constant maintenance. • lack of resilience and durability rfid: radio frequency id a card that can store information and communicate it using radio frequency, thus no physical contact is required between card and reader. • highly resilient and unaffected by outside elements. • fast • might cause health issues, if used in long range. • expensive • frequency collision when multiple cards are used in the same range. biometrics unique and measurable human features, like voice, fingerprints, dna, or retina scan. • theoretically impossible to copy or forge. • highly resilient and unaffected by outside elements. • expensive • complicated registration process • the matching process requires huge databases and high processing power. category type of users/cars estimated number of cars* suggested fees (in dollars) how to apply issue renew replace blue personal cars 4.5-5.5 million 5$ 3$ 10$ online red government cars 67-94 thousand free free 20$ through department black transport (buses, taxis) 1-1.5 million 5$ 5$ 10$ online gold company cars, light/heavy goods vehicles 1 thousand 10$ 8$ 20$ through company silver visitors, foreigners >1 thousand 10$ n/a 10$ online purple multiple cars >1 thousand 15$ 10$ 25$ at office green other uses (ex. generators) 0.5-1 million 5$ 5$ 10$ at office noor ahmed khudhur al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 148157(2017) 151 • each user must apply and pay a small fee for a card that is valid for 1 year, after which the card must be renewed if the program is still in effect. • vehicles will be registered by plate numbers, as it is the most suitable option for category selection. the green category (for fuel uses other than cars) will have to be issued on caseby-case bases. • the amount of fuel given a user should be determined a specialists to ensure it is enough for the every users' needs. • ration sizes will not be fixed rather will be set as an equation combing the category and car type, thus the rationing can be adjusted or cancelled and the cards would continue to work properly, it will also make it harder to tamper with the system. • card readers will be employed at gas stations, then used by the station operators to read the cards and know the ration size and when a user is due one. • all other procedures will continue as usual. • the system should provide for all cost internally, which means the fees paid for the cards should go to staffing, purchasing of equipment and advertisement necessary for the project. ideally, no extra government spending would be needed for the program, even if an external company is contracted. • the time between rations is also limited, once a user receives the ration, the card is disabled until it is time for another ration, this way users can't deceive operators or conspire with them receive more rations than they are allowed. 2.1 parts of the system the system has three critical parts for operation: a. database: the system requires an accurate, upto-date database, large enough to hold all users information. b. operators: gas station workers are responsible for running the distribution of rations, thus they are critical to the system. c. cards: as the system authentication token, the system relies on the authenticity of the cards to work properly. 3. risks, threats and mitigation • there are common risk factors and threats associated with all rationing system and online systems such as the one proposed, in this section we will look at these common risks and discuss methods of mitigation that could be implemented. 3.1 insider threat insider threat is a disruption to a processes introduced by a person, or group of people with legal access to the system, such as employees, mangers, suppliers or contractors...etc. if it is intentional, it is commonly known as corruption [15]. cpni report [16] listed some of the motivations for insiders to break the law, financial gain was on the top of the list, followed by: ideologies, desire for appreciation, outsider loyalties and vengeance. some insider threats though, are not intentional, as people can simply make mistakes if they lack the experience or training necessary [15]. in our proposed system, the insider threat is extremely high, because of the dependence on registration employees for correct issue of cards as well as station workers for honest distribution of fuel. some precautions can lessen this threat or reduce its effects: • registration employees have to go through background checks and interviews, to ensure they have no past criminal records or questionable affiliations. • matching every application with the national car registration database at the directorate of traffic departmentthis limits the employee's ability of issuing false cards. • for station operators, some training and guidelines are required to reduce errors, the system interface should also simple and straightforward, clearly displaying the needed information. • the card readers usually have the ability to compile a list of cards used, so by using this list, the amount of fuel that supposedly been dispensed for one day can be calculated then matched with the actual fuel levels, highlighting any discrepancy that needs further investigation. • a mechanism must be implemented to allow users and operators to report any suspicious behaviour, or faults in the system they notice. noor ahmed khudhur al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 148157(2017) 152 3.2 counterfeiting counterfeiting is the creation of fake documents or the replication or modification of legitimate ones [17]. it is a major threat for systems that use an authentication process for identifying users. a number of anti-counterfeiting measures have developed over the years, they are however not perfect and instead of making counterfeiting impossible, these measures simply make it not worth the effort, i.e they make the cost of making a counterfeit document exceeds the cost to be gained from breaking the system. [18] for this reason, the intensity of anti-counterfeiting is proportional to the value of the system itself, so in our case, the counterfeit measures are medium levels, as the cost of creating a secure, hard to replicate card, should be in line with the cost of fuel rations themselves. the system will have a combination of security features known as overt, covert and forensics. thus, the cards are equipped with the following features: • overt (easily noticeable by any user or operator): hologram, watermark. • covert (requires a device or special light to detect):, uvfluorescent image, microprinting. • forensics (used by specialists after confiscation to study the counterfeit): a magnetic stripe, containing the user name, plate number, issue and category type, this is not used in authentication, only as a match with original chip. • read/write rfid cards provide authentication, read-only do not offer authentication [9]. • derived key encryption: this method of encryption derives the decryption key from cards’ serial numbers, using a unified secret algorithm [9]. if one key is compromised, it does not mean all of them are. figure 1 shows a template for the card suggested with all the security features. • a template for the card suggested is shown in figure 1, highlighting the security features required. it’s also important to raise awareness about fraudulent documents and how to detect them. fig. 1. a template for the card suggested. 3.3. system failure a system failure is the event of a system failing to function as intended under all conditions at all times [19]. rationing systems are prone to failures due to their wide scope of application and their nature as emergency measures instead of well thought-out plans. the huge numbers and the diversity of users create all kinds of exceptions and puts pressure on the performance. urgency cause lack of proper debugging or a trial period, as well as the possibility of going over budget or cutting corners, all these factors increase the chances of system failure [19]. stoneburner, et.al [20] gave six possible responses for risk management: assumption, avoidance, planning, limitation, transference or noor ahmed khudhur al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 148157(2017) 153 research. for a rationing system, complete avoidance is unattainable, so is transference, thus we must accept the possibility of system failure, instead we need a recovery plan and ways to limit the affects of one system failing on any other. the following guidelines could lessen the effects of potential system failure: • back up the database every day. update it only once per day, before backup, thus if the data is damaged during update, there is always a copy. • card readers are ideally equipped to keep a record of all transactions. in the case of the system going offline, operators are capable of authorizing sales, this way they must visually identify the card, and while it is possible to take some small advantage of such system failure, the risks are manageable and preferable to halting all sales, it is also possible to detect any fraud once the system is back online and take action. • provide multiple readers per station, if one is down, operators can replace it until it is fixed. 3.4 hacking the registration system in the case of a system hack, it's becomes possible to issue fake or duplicate card or change details like the category, if this was done on a small scale it could possibly go un-noticed, thus the some measures are suggested to reduce the likelihood of successfully hacking the system : • implement ssl, use anti-sql injection techniques, firewalls, and input control, particularly on online application forms. • match entries of the application form with the national vehicle-licensing database, refuse the application if it didn’t match. • plate numbers are unique, so a simple check can ensure they are never repeated. • send the card to the registered or work address; or require proof of identity before handing it out to the user, in case the form was filled by someone, claiming to be someone else. • in the case of someone being unable to apply because of a repeated plate number, allow them to visit a registration office, once their ownership of the car is proven, the old card is disabled and a new one is issued. 3.5 hacking the system database in the case of database hack, rations for any number of people could be manipulated to increase rations or reduce waiting period, the following measures are suggested to lessen the affects of a potential database hack: • limit the functionality of readers, allow them to read values and alert the system, this will automatically set the value of the variable ‘last use’ to the current date. all other values should be locked, read-only values and. • the database is updated once per day at night to add new cards or remove reported ones, this will mean one-day waiting period before a new card is usable, and a one-day window for fraudulent cards to take rations, which is negligible. after update, the database is backed ups. so the next day, a comparison between the back up and the database before update should reveal any unauthorized changes. • the ration size and waiting period between rations is not identified as a fixed value within database but is computed from other values, such as category and vehicle type (ex. ‘bus’, ‘coach’ or ‘car’).this way, a simple number change is not possible instead the only way to change a ration size or waiting period is changing the algorithm that calculate it, which can be easily monitored and noticed. 3.6 problems with the transmission: listening, interference and health concerns the rfid technology is contactless, meaning a card not inserted in the reader device but is transmitting information wirelessly through air, this introduces a set of problems, such as outsiders listening in on the transmission, compromising privacy of the users, also when multiple card are used near each other the signals may interfere confusing the reader device and disrupting the process. one more concern that rose up in recent years is the effect of transmission on safety, and if constant exposure to the signal can cause health issue, the issues listed above are illustrated in figure 2. noor ahmed khudhur al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 148157(2017) 154 fig. 2. risks caused by rfid wireless transmission. one way to limit all the previous concerns is using passive ultra high frequency transmission, making the range the transmission shorter (around 1 meter) complicating listening and reducing interference greatly, the use of passive transmission as well as the lower range will reduce all health and safety concerns. other ways to protect privacy is using encryption between the reader and the card (derived key encryption), as well as between the reader and the central system and limiting the information stored on the card not to include personal data. 3.7. tampering with readers all readers should be located inside secure buildings when not in use, along with regular inspection for the devices, operators would be held responsible in the event of failing to report any stolen or damaged devices. 3.8 lost or stolen cards cards are the method of authentication, it is important that if they are stolen or lost, that we have good measures for replacing them without creating redundancy, on the other hand, if someone suspect that their card has been duplicated there should be a way to resolve the situation. the following measures are suggested • a reporting system is necessary to report any missing cards, or if a person is being rejected by the system and suspects his card has been compromised somehow. • cards are disabled after use, until the waiting period between rations has passed; a missing card reported early could only be used few times, limiting the damage. • when a card is reported missing, it must be disabled before a new one is issued, and extra fees are charged for re-issue this discourages people from making false claims or being careless. 3.9. selling cards or unneeded shares there is always a risk of people selling their cards or any rations they do not need, the mitigation process is policy based, not technological, and it varies between personal cars and company, or government cars. a. private use (blue, black, purple, green): • offering a discount for next year rations for a percentage of fuel saved, for example, if a user is assigned 52 rations per year, yet received 46 or less, that's 10% saving, making them eligible for a discount . this will discourage selling rations as well as encourage reasonable fuel consumption. • any person discovered to have sold or bought a card, will be liable to a fine. it is easy to discover sold cards since they contain a picture and plate numbers. b. government and company cars (red, gold, black): • the old card must be submitted for renewal, failing to present it makes the owner liable to a fine. a heavier punishment must be set for cardholders caught selling a card. 4. implementation 4.1 database the system database should be simple and straight forward, most items in the database would be read only, and inserted directly from the vehicle registration database rather than manually, while the values of the time stamp and permission set to be automatically calculated by the system. noor ahmed khudhur al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 148157(2017) 155 table 3 shows the fields of the proposed database and their data types. note that the ration size is not fixed, rather it is calculated by an algorithm that uses both the category vehicle type to calculate, the same is true for the duration, this is meant to give the system some flexibility so the rations can be adjusted depending on supply and demand, it is also a security measure because if the system was hacked and a single number is changed it may not be noticeable, but a change in the algorithm would be discovered immediately. table 3, the system database. 4.2. equipment every gas station is provided with a number of short-range rfid readers, compatible with the cards. a good practice is to have the supplier company do the installation or supervise it. all readers must: • have derived key decryption, for contact with the card. • use encryption for contact with the central system. • be equipped with clear display screens that show all the required information to dispense fuel. • have a memory space large enough to record transactions up to a month • can send daily records to the central system, to be compared with the fuel dispensed from station. to have all these requirements, the readers might have to be developed specifically, however, it's a common practice for developer companies to offer customizable rfid readers, and while the extra features will have added cost, but it's necessary for risk management. 4.3 delivery plan as an emergency system, it is designed to have minimum changes in infrastructure and must not disrupt regular procedures during implementation; it does however require preparation that includes hiring registration workers, building the system, and purchase of devices as well as any possible contracts if the implementation was to be fully or partially outsourced. there should also be an adjustment and training period, where cards are distributed to users but no ration is applicable yet. this will be very useful in finding bugs or required adjustment to the program, before it goes into full operation. another suggestion is to have a promotional campaign throughout the project to get the public informed. figure 3 shows the suggested 3 months plan for the implementation of the system. fig. 3. delivery plan. field type serial number pk name read only category read only plate number read only vehicle type read only time stamp of last use automatic time for next allowed use automatic permission(boolean) automatic month1 month2 month3 hiring/background checks purchasing devices set up website/ database promotional campaign installing devices training operators set up registration offices open registration issue cards printing cards/outsourcing the printing trial period launch the system noor ahmed khudhur al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 148157(2017) 156 5. conclusion this paper suggested a system for fuel rationing that could be applied within three months ideally. the paper suggest the use of rfid cards for authentication, and a 7 category allotment system to account for the needs of the public, the system proposed accounts for the risks associated with such a system and their mitigation. however, it is sufficient for emergency and temporary use only. a more durable system would require case studies, interviews or surveys among affected parties as well detailed cost analysis. 6. references [1] r. h. bezdek and w. b. taylor, “allocating petroleum products during oil supply disruptions.,” science, vol. 212, no. 4501, pp. 1357–63, jun. 1981. [2] d. fleming and s. chamberlin, “teqs (tradable energy quotas):a policy framework for peak oil and climate change,” 2011. [3] s. h. halpin, “home rule in nj and hurricane sandy recovery,” in american society for public administration 2013 annual conference, 2013. [4] s. kaufman, c. qing, n. levenson, and m. hanson, “transportation during and after hurricane sandy,” 2012. [5] d. m. guillaume, r. zytek, and m. reza farzin, “iran: the chronicles of the subsidy reform,” 2011. [6] h. rahdari, m. zargarzadeh, h. nozari, and l. soltani, “gasoline rationing plan in iran : a symptomatic solution,” in 27th international conference of the system dynamics society, 2009. [7] p. hanafizadeh, z. navardi, and j. bamdadsoofi, “an attitude study on the environmental effects of rationing petrol in tehran,” energy policy, vol. 38, no. 11, pp. 6830–6848, nov. 2010. [8] k. michael and m. g. michael, “historical lessons on id technology and the consequences of an unchecked trajectory,” prometheus, vol. 24, no. 4, pp. 365–377, dec. 2006. [9] k. finkernzeller, rfid handbook, 3ed ed. wiley, 2010. [10] keith e. mayes and k. markantonakis, smart cards, tokens, security and applications. 2008. [11] r. bolle, guide to biometrics. springer, 2004. [12] r. bhasker and raj, bar codes. tata mcgraw-hill education, 2001. [13] n. bartneck, v. klass, and h. schoenherr, optemizing processes with rfid and autoid. publics publishing, 2009. [14] cosit.gov.iq,'central statistical organization iraq', 2013. [online]. available: http://www.cosit.gov.iq/ar/2013-03-29-0838-49. [accessed: 10jun2015]. [15] s. j. stolfo, s. m. bellovin, s. hershkop, a. d. keromytis, s. sinclair, and s. smith, insider attack and cyber security. 2008. [16] cpni, “cpni insider data collection study report of main findings,” 2013. [17] consilium, “technical terms related to security features and to security documents in general.” [online]. available: http://prado.consilium.europa.eu/en/glossary popup.html. [18] cardlogix, “graphics and security: printing guide,” 2011. [19] k. t. yeo, “critical failure factors in information system projects,” int. j. proj. manag., vol. 20, no. 3, pp. 241–246, apr. 2002. [20] g. stoneburner, a. goguen, and and a. feringa, “risk management guide for information technology systems recommendations of the national institute of standards and technology,” 2002. ���1، ا���د��13 � ا�� ارزم� ا������� ا��� م � ر ا��� ��� � ،148-157 )2017( 157 ��� د &$�)��ام & $%$ت ط ارئ� � rfid ا��% ز*( ا�(� ر ا��� ���� noorea04@yahoo.com : ا ����و � ا����� �� ا��+ 4 ا�4 ا�3.�"* ���".21 1 �0 ا�()ارد و ا��,.�ا�,�ور�* ��()اط���، &� ھ�ا ا��%$ #��"�ف �� ھ�ه ا���� وط�ا� �� ا������ ھ� ا�� ا��� ا��� ا�)a)د �(�� =����d &� ا�"�اق، 1�1ا .ة ا�;�وa.ت ا�((�� ا#�@?ل ا���.م �1 =����9. وا ��.ت وا�(;.ط� ا�(:.��* �9.، �8 �)م 7��)�� �.م ��)ز� �ر�* &e و�7ون =@���ات *gواط *h��7 �9iا d8?8 ل?j d����= ��)ت ا��)اريء و� .� ا���� ا��%��*j?�9. و��m�."1 *�h�9.، و�3��ط 7.���.م ان ��)ن �%. <4d6963726f736f667420576f7264202d20c7cde3cf20e6d3c7e3ed20e6d5ddc7c133302d3339> al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 14, no.2, june, (2018) p.p. 3039 optimization of diffusion bonding of pure copper (ofhc) with stainless steel 304l ahmed ali akbar akbar * sami abualnoun ajeel** safaa mohammed hassoni*** *,**department of production engineering and metallurgy/ university of technology ***institute of technology baghdad/ middle technical university ***email: as_5599@yahoo.com (received 10 april 2017; accepted 28 november 2017) https://doi.org/10.22153/kej.2018.11.002 abstract this work deals with determination of optimum conditions of direct diffusion bonding welding of austenitic stainlesssteel type aisi 304l with oxygen free high conductivity (ofhc) pure copper grade (c10200) in vacuum atmosphere of (1.5 *10-5 mbr.). mini tab (response surface) was applied for optimizing the influence of diffusion bonding parameters (temperature, time and applied load) on the bonding joints characteristics and the empirical relationship was evaluated which represents the effect of each parameter of the process. the yield strength of diffusion bonded joint was equal to 153 mpa and the efficiency of joint was equal to 66.5% as compared with hard drawn copper. the diffusion zone reveals high microhardness than copper side due to solid solution phase formation of (cuni). the failure of bonded joints always occurred on the copper side and fracture surface morphologies are characterized by ductile failure mode with dimple structure. optimum bonding conditions were observed at temperature of 650 ◦c, duration time of 45 min. and the applied stress of 30 mpa. the maximum depth of diffuse copper in stainless steel side was equal 11.80 µm. keywords: diffusion bonding, pure copper, stainless steel, 304 l. 1. introduction joining dissimilar metals demands for increasing importance in many applications to utilize hybrid structures and compounds properties like high strength, thermal conductivity and good corrosion resistance [1]. the applications of dissimilar metals such as austenitic stainless steelcoppers (ofhc) are widely used in traditional and nuclear power plants [2]. however, the welding of austenitic stainless steel with copper alloys by conventional welding processes is not recommended by these methods because of probability of formations of newly intermetallic compounds at the weld pool. copper and its alloys are majorly utilized for pipelines of heat exchangers; valve and clad plate for steel hulls of small ships, etc. alloys of copper have enough resistance corroded in seawater [3]. broadly, the application of austenitic stainless steel to copper joints is utilized in the heat exchanger which consists of plates of austenitic stainless steel to copper [4]. in vessel apparatuses of the international thermonuclear experimental reactor austenitic stainless steel and copper alloy are considered as a chief structure of materials for the first wall and find out systems. the austenitic stainless steel is also utilized in the nuclear surroundings [5]. innovative joining operation of similar and dissimilar materials is provided by diffusion bonding welding process without producing macroscopic distortion; with minimum dimensional tolerance and no phase transformation or microstructional change occurred during the welding process [6]. a ahmed ali akbar akbar al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 3039 (2018) 31 diffusion bonding process also permits the production of highquality joints with little or no need for post weld machining [7]. design of experimental (doe) was used in this work to get a suitable number of samples to be tested to characterize the effect of bonding variables (temperature, duration time and applied load) on the diffusion bonding joints. bilgin (2009) studied the interfacial properties of diffusion bonding of stainless steel type 304l with ti-6al-4v using cu interlayer. this work was applied at temperature range of (820-870) c◦, time range of (50-90) min. and load of 1mpa. the joints were examined using sem, eds, shear test and micro hardness test. at different conditions to predict optimum conditions of shear strength at 870 c◦, and duration time of 90 min. due to better coalescence [8]. xiong (2012) studied the diffusion bonding of stainless steel to copper with tin, bronze and gold interlayer. the diffusion bonding of two materials was obtained under temperature range of (830-955) c◦, load 3mpa and duration time of 60 min. the optimum conditions observed for this work were at 850 c◦ to get tensile strength of 228 mpa for tb-au interlayer. the microstructure of joint was examined using sem and eds [9]. sabetghadam (2010) evaluated the microstructure of diffusion bonded joint between stainless steel 410 and copper using ni as interlayer. the bond joints were applied at temperature range of (800950) c◦, load of 12 mpa and duration time was 60 minutes in vacuum of (1.3 x 10-2 pa). the microstructure and phases near bonding interface were examined using optical microscope, sem and eds. the result indicated an increase in thickness of reaction layer with an increase in temperature [10]. kaya (2011) worked on the diffusion bonding of stainless steel with copper by two methods convential diffusion bonding and non-conventional diffusion bonding by applied external current. the specimens to be bonded were in dimensions of 10mm. dia. and 35mm. length. the bonding conditions were 875 c◦, duration time 30 min. and applied load 3mpa, with heating and cooling rate of 20 c◦/min. the interface of bonded joints was examined by tensile test and sem&eds. the strength of conventional bonding was 159 mpa and for nonconventional 169 mpa. the total diffusion of convential was 6.4% wt. while for non-convential was 9.1% wt [11]. all previous studies were restricted to the evaluation of the diffusion parameters influence and microstructure on the interface of the diffusion area. but, there are no studies of the characterization of the influence of the diffusion bonding metallurgical transformation on the corrosion behavior of (aisi 304l/pure copper) bonding joints. the present work makes an effort with a contribution to this challenging dilemma. 2. experimental 2.1 preparation of vacuum diffusion bonding unit in order to evaluate the sound diffusion bonding of two dissimilar materials of pure copper (ofhc) grade (c10200) and austanitic stainless steel type aisi 304l, the diffusion bonding requires to be applied in vacuum. joining under vacuum reveals minimum impurity content, even in the case of high reactive metals. vacuum provides faster and more complete degassing of joined materials and removal of oxides, impurities and contaminants from both surface and bulk materials. the system consists of vacuum diffusion pump, double stage rotary vacuum pump, electrical loading system with capacity of 50 ton, vacuum tube furnance with heating system, vacuum fitting and cooling system for furnace and diffusion as shown in fig. (1). fig .1. vacuum diffusion bonding unit. 2.2 materials materials used in this work were wrought austenitic stainless steel aisi 304l according to (astm volume 01.01) and hard drawn pure copper (ofhc) grade (c10200) according to (astm volume 02.01). ahmed ali akbar akbar al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 3039 (2018) 32 table 1, mechanical properties of two materials used. materials yield strength(mpa) ultimate strength (mpa) elongation % hardness stainless 304l 210 564 58 hrb=85 copper(ofhc) 230 255 28 hb=65 2.3 specimens preperation for diffusion bonding process the materials to be joined by diffusion bonding were pure copper(ofhc) and stainless steel 304l. cylindrical samples of 15mm diameter for each lengths were used with 30 mm and 60 mm for copper and stainless steel respectively[12]. the mating sample surface was prepared using convential grinding on 1200 grade sic papers followed by polishing with diamond paste using fabricated holder to get flat surface . the specimens were cleaned in ultrasonic bath using acetone for 15 min. to remove adhered contaminations and dried in air before bonding. 2.4 doe (design of expermental) 2.4.1 selection of process parameter (surface response) the working range for each parameter is given in table (2). this represents boundary of optimum conditions to be searched according to (0.5-0.8 melting temperature) [6]; (4-13% бy) applied load and duration time range (15-75) min. from previous works. these ranges are selected according to the recommended optimum ranges of temperature, the duration time and applied load of diffusion bonding welding process [14]. table 2, working ranges of selected parameters. 2.4.2 construction of the experimental design matrix the value of coded variables and uncoded variables for experimental design is shown in table (3). table 3, experimental design matrix. exp. numbers coded value original value bonding temp.(◦c)t1 bonding time(min.)t2 bonding pressure(mpa)t3 bonding temp.(c◦) bonding time(min.) bonding pressure(mpa) 1 -1 -1 -1 600 30 15 2 +1 -1 -1 700 30 15 3 -1 +1 -1 600 30 25 4 +1 +1 -1 700 30 25 5 -1 -1 +1 600 60 15 6 +1 -1 +1 700 60 15 7 -1 +1 +1 600 60 25 8 +1 +1 +1 700 60 25 9 -1.682 0 0 550 45 20 10 +1.682 0 0 750 45 20 11 0 -1.682 0 650 45 10 12 0 +1.682 0 650 45 30 13 0 0 -1.682 650 15 20 14 0 0 +1.682 650 75 20 15 0 0 0 650 45 20 16 0 0 0 650 45 20 17 0 0 0 650 45 20 18 0 0 0 650 45 20 19 0 0 0 650 45 20 20 0 0 0 650 45 20 max. min. parameters 750 550 temperature (◦c) 75 15 duration time (min) 30 10 applied pressure (mpa) ahmed ali akbar akbar al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 3039 (2018) 33 where: t1: the code value of temperature; t2: the code value of duration time; t3: the code value of applied load. 3.7.1 tensile test of diffusion bonded joints to evaluate the tensile strength of bonded joints after welding, the bonded joint specimens were sectioned into small specimens for microstructure, mechanical properties tensile test. the tensile strength value was obtained by average value for tests. the tensile test specimens were cut by using wire cutting machine from bonded joints according to (astm e8-89) , in such a way that the weld zone was positioned at the center of gauge length. the tensile test specimen shown in fig. (2), was applied by using universal testing machine type wdw 200 e with cross speed 0.1 mm/min. dimensions (mm) of tensile test specimen with thickness of (6mm) according to astm e8-89 tensile test specimen fig. 2. specimens for tensile test. 4. results and discussions 4.1 tensile test of diffusion bonding joints the bond strength of the bonding joints represents the response for the program min tab16. as shown in fig.3 (a). the results from tensile tests are shown in table (3). the fracture of most tensile test specimens was occurred in the copper side not at the bond line as shown in fig.3 (b). this means the bond area is much stronger than copper side; this due to the used of vacuum atmosphere conditions which lead to better coalescence. this results in complete mating of two surfaces, and diffusion of copper atoms leads to good bonding. fig. (a) fig. (b) fig. 3. (a) a set of diffusion bonding joints at different bonding conditions. ( b) fracture of diffusion bonding joints. ahmed ali akbar akbar al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 3039 (2018) 34 table 3, results of tensile tests of bonding joints. 4-2 parametric analysis of bond strength the main effect of plot of each variable of (t1, t2 and t3) on the bond strength is shown in figure (4). the bond strength increases with an increase in temperature (t1) until reaching maximum value at temperature of 650 ◦c and then decreases until reached a temperature of 750 ◦c. this indicates maximum strength at 650 ◦c with higher bond strength than other temperatures values of bonding. the effect of a second variable that is, duration time of bonding (t2) on the bond strength of 15min. gets on the acceptable bond strength, but when time increases fluctuation in bond strength can be seen until reaches the maximum value of 75min. finally, the effect of third variable (t3) is applied load on the bond strength at low values of load. this indicates low bond strength, but the maximum value of bond strength was observed at applied stress of (30 mpa) due to complete mating surface between two bonding metals used. fig. 5. main effects on fracture stress. 4.2.1 response surface regression the analysis of results of bond strength versus t1 (temperature), t2 (duration time) and t3 (applied stress) was done using uncoded units of input data. regression was estimated coefficients for bond strength in order to obtain the significance by calculating (p-level) for each coefficient to determine which of these significant factors have effect on the bond strength. depending on the significance level (α=0.05), the coefficient with plevel value is greater than 0.05 which is not significant like (t3, t22, t33, t13 and t23), coefficients which have p-level less than 0.05 like (to, t1, t2, t11and t12) represent the effective values on the bond strength of t1 temp. (◦c) t2 time (min.) t3 stress (mpa) fracture stress (mpa) fracture location ultimate strength(mpa) elongation% 600 30 15 128.0 at copper 178 26 700 30 15 30.0 at interface 113 8 600 30 25 123.0 at copper 210 44.5 700 30 25 45.0 at interface 76 5.5 600 60 15 38.0 at interface 49 3.5 700 60 15 58.0 at copper 142 11.5 600 60 25 80.0 at copper 193 22.5 700 60 25 113.0 at copper 191 24 550 45 20 53.0 at copper 120 12.5 750 45 20 4.8 at interface 56 4.5 650 45 10 57.0 at copper 138 16 650 45 30 153.0 at copper 210 40.5 650 15 20 128.0 at copper 200 27 650 75 20 127.0 at copper 200 40.5 650 45 20 110.0 at copper 200 38.5 650 45 20 49 at interface 82 3.5 650 45 20 105.0 at copper 210 42.5 650 45 20 112.0 at copper 184 44.5 650 45 20 107.0 at copper 173 24 650 45 20 112.5 at copper 225 44.5 ahmed ali akbar akbar al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 3039 (2018) 35 diffusion bonding joints of two materials, therefore the mathematical model of significant parameters may be written as shown in equation (1). y = -1711.34 + 8.19t1 29.85t2 0.01 t1 2+ 0.04t1*t2 …(1) 4.2.2. anova results of bond strength the analysis of variance (anova) for the bond strength is shown in table (4); it is made by using fisher test (f-test) and results. it can be observed from this table that, the coefficient of r.sq=92.80% but the r.sq (adj.) =86.32%. the difference between two values of r is small therefore, this means the three variables (t1, t2 and t3) qualified in variation of bond strength by (86.32%) and about of (13.68 %) due to random error and noise or the effects of other variables. depending on significance value of (0.05), observed from the table, the total of p value is less than 0.05 therefore the test is significant. table 4, avona for bond strength with significant level (0.05). source df seq. (ss) adj. ss adj.(ms) f p regression 9 28882.0 28882.0 3209.1 14.32 0.000 linear 3 8649.8 18994.4 6331.5 28.26 0.000 square 3 12451.0 12451.0 4150.3 18.52 0.000 interaction 3 7781.2 7781.2 2593.7 11.58 0.001 residual error 10 2240.6 2240.6 224.1 ---------- lack of fit 5 1588.2 1588.2 317.6 2.43 0.176 pure error 5 652.4 652.4 130.5 ----------- total 19 31122.7 ------------------------- r-sq. =92.80% r-sq.(pred)=55.86% r-sq. (adj)=86.32% 4.2.3 optimization of surface response (bond strength) the optimum value of bonding conditions is calculated using the equation (2), to predict the maximum value of bond strength of diffusion bonding joints for various bonding conditions. �� = ��� � � �� � � � …(2) where: di = individual desirability. yi = response. ti= target. li= lower limit values of the response. r= unit weight factor (usually = 1). the calculated optimum results are shown in table (4); optimum bonding conditions was observed at experiment number 12, with bonding conditions of 650 ◦c, 45 min. and 30 mpa applied stress. the high value of di equal to (1) represents the maximum value of bond strength and the value of di=0 represents the minimum value of bond strength [14]. the maximum tensile strength of bonding joint was obtained at the bonding conditions of temperature at 650 ◦c, duration time of bonding at 45 min. and applied load of complete coalescence at 30 mpa. joint efficiency is attributed to the quality of the joints. therefore, joint efficiency was estimated. [15] as follow: joint efficiency = 153 mpa/ 230 mpa (for copper) % = 66.5% joint efficiency= 153 mpa/550 mpa (for stainless steel) %= 28% 4.3 surface and counter plots the response surface analysis which has two types of plots, the first is three dimensions (3d) representing the surface plot. the second is the two dimensions (2d) indicating the contour plot. the two plots were studied the combination effects of bonding parameters (t1, t2 and t3) on the bond strength of joints. ahmed ali akbar akbar al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 3039 (2018) 36 table ranks of response surface of results. 4.3.1 effect of temperature and duration time on bond strength figures (5 a and b) indicate 3d surface and 2d contour plots which show combination effect of t1 (temperature) and t2 (duration time) at constant level (middle value) of t3 (applied stress) equal to (20 mpa.) on the bond strength. figure. (5 a) shows the effect of temperature and duration time on the surface response bond strength. it can be observed from this, the bond strength increases with an increase in temperature and duration time but the effect of temperature is more effective than duration time. the optimal bonding conditions are temperature of 650 ◦c and duration time at 45 min. the increase in temperature above 650 ◦c leads to rapid grain growth which leads to low bond strength [16]. fig. (5 b) represents the 2d contour plot for temperature with duration time. it indicates that the maximum bond strength observed at minimum temperature and duration time but it cannot be result in sound diffusion bonding joints. the optimum bonding condition at the range of 120180 mpa as shown in fig. (5 b). the combinations effect of temperature and duration time in contour was observed at maximum temperature of 650 ◦c and maximum duration time of 45 min., due to complete coalescence between two coupling surface and high diffusion rate. (a) (b) fig. 5. effect of temperature and time on bond strength (a) 3d surface plot (b) 2d contour. no. t1 (◦c) t2 (min.) t3 (mpa.) fracture stress. (mpa.) di rank 1 600 30 15 128.0 0.8313 2 2 700 30 15 30.0 0.1700 18 3 600 30 25 123.0 0.7975 4 4 700 30 25 45.0 0.2712 16 5 600 60 15 38.0 0.2240 17 6 700 60 15 58.0 0.3589 13 7 600 60 25 80.0 0.5074 12 8 700 60 25 113.0 0.7300 5 9 550 45 20 53.0 0.3252 15 10 750 45 20 4.8 0.000 20 11 650 45 10 57.0 0.3522 14 12 650 45 30 153.0 1 1 13 650 15 20 128.0 0.8313 2 14 650 75 20 127.0 0.8245 3 15 650 45 20 110.0 0.7098 8 16 650 45 20 49 0.5209 11 17 650 45 20 105.0 0.6761 10 18 650 45 20 112.0 0.7233 7 19 650 45 20 107.0 0.6896 9 20 650 45 20 112.5 0.7267 6 ahmed ali akbar akbar al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 3039 (2018) 37 4.3.2 effect of temperature and applied stress on bond strength. figures (6 a and b) illustrate combination effects of temperature and applied stress on the bond strength. figure (6 a) shows gradual increase in bond strength until reached maximum value at load of 30 mpa. the bonding load was applied in order to secure a tight contact between the bonding surface and a vital condition for the interdiffusion atoms of metals jointed. if the applied stress is less than the optimum value, then the bond strength decreases. the optimum bonding temperature can be seen at 650 ◦c and at maximum applied load of 30 mpa. the effect of temperature on bond strength is more effective than the effect of applied load and the higher bond strength is 30 mpa. (a) (b) fig. 6. effects of temperature and applied stress on bond strength (a) 3d surface plot (b) 2d contour plot. 4.3.3 effect of time and applied stress on bond strength. the effect of the two variables of duration time (t2) and applied stress (t3) on the surface response bond strength is shown in figures (7) a and b. fig. (7 a), shows higher effect of duration time than applied load. the right region of plot shows high change in applied stress up to 30 mpa. these results are combined with the effect of duration time on the bond strength,when time increases until reached 45 min. with an increase in applied stress to reach 30 mpa. at this point maximum value of bond strength is observed. fig. (7 b) shows combination effects of high applied stress of 30 mpa and high duration time of 45 min. to get optimum value of maximum value of bond strength. mating surfaces are expanding almost instantaneously. when the applied load increases more than the increase in temperature this leads to plastic deformation and doesn’t get sound bonding joint between the two materials used [17]. (a) (b) fig. 7. effects of time and applied stress on bond strength (a) 3d surface plot (b) 2d contour plot. ahmed ali akbar akbar al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 3039 (2018) 38 5. conclusions 1. the dissimilar diffusion bonding joints show lower tensile strength than the base material of hard drawn pure copper (ofhc) side and the maximum bond strength is 153 mpa. 2. vacuum diffusion bonding unit has been successfully prepared and reached vacuum approximately of (1.5 * 10-5mbr). 3. the maximum tensile strength of diffusion bonding joint was observed for diffusion bonding joint at optimum bonding conditions of 650 ◦c, 45 min., and applied stress of 30 mpa, annealed at temperature of 800 ◦c, for 30 min. 4. the equation represent the effect of bonding conditions between hard drawn copper and austenitic stainless steel 304l with significant effects of bonding parameters was: y = -1711.34 + 8.19t1 29.85t2 0.01 t12 + 0.04t1*t2 5. the strong effects of diffusion bonding parameters are temperature˃ duration time˃ applied load. 6. the efficiency of optimum bonding joint was higher as compared with hard drawn copper and lower as compared with austenitic stainless steel. 6. references [1] j. c., lippod koteki d. j, “welding metallurgy and weldability of stainless steel”. new jersey: wiley (2005). [2] n. k. srinivasan, welding technology, fourth edition, romesh chander khanna, khanna (2012). [3] d. feron, “corrosion behavior and protection of copper and aluminum alloys in seawater”, wood head publishing limited and crc press llc, (2007). [4] k. bhanumurthy, d. joyson, a. laik, “diffusion bonding of nuclear materials”, brac nem letter, (2013), issuf no. 331. [5] r.k.roy, s.singh “joining of 304ss and pure copper by rapidly solidified cu-based braze alloy”, fusion engineering and design, (2011) 452-455. [6] kunda s., chatterjee s., mechanical properties of diffusion bonded joints between titanium and stainless steel with nickel interlayer, material science and engineering, (2007). [7] j. grum, slabe j. m,” the use of design and response surface methology for fast determination of optimal heat treatment conditions of different ni-co-mo surface roughness layers”, journal of material processing technology, (2014). [8] n. ozdemir, b. bilgin, interfacial properties of diffusion bonded ti-6al-4v to aisi 304 stainless steel bt inserting copper interlayer, journal of advanced manufacturing technology, (2009). [9] jiang-tao xiong, diffusion bonding of stainless steel to copper with tin bronze and gold interlayer, journal of material engineering and performance, (2012). [10] h. sabetghadam, a. zarei hanzaki, microstructure evaluation of 410 ss/cu diffusion bonded joint, journal of material science and technology, (2010). [11] yakop kaya, nizamettin kahraman, anovel approach of diffusion bonding of copper to stainless steel, journal of engineering manufacture, (2011). [12] ahmed ali akber akber, “diffusion bonding of oxygen high conductivity copper to austenitic stainless steel” phd thesis, university of technology, (1996). [13] rohit garg "effect of process parameters on performance measures of wire electrical discharg machining", ph.d. thesis, mechanical engineering department, national institute of technology, kurukshetra, (2010). [14] montgomery, d. c. and runger, g. c. applied statistics and probability for engineers, john wiley and sons. (2010). [15] s.assarzadeh and ghoreishi, statistical modeling and optimization of the edm parameters on wc-6% co composite through hybrid response surface methodologydesirability function approach, international journal of engineering science and technology, (2013). [16] m. balasubramanian, application of boxbehbken design of fabrication of titanium alloy and 304 stainless steel joints with silver interlayer, materials and design, (2015). [17] pilling j., solid state of superplastic a a 7475, materials science and technology, (1987). )2018( 14-21، صفحة 2د، العد14دجلة الخوارزمي الهندسية المجلماحمد علي اكبر اكبر 39 امثلية وصالت الربط االنتشاري للنحاس خالي األوكسجين عالي الموصلية مع الفوالذ المقاوم 304l للصدأ احمد علي اكبر اكبر* سامي ابو النون عجيل** صفاء محمد حسوني*** الجامعة التكنلوجية /قسم هندسة االنتاج والمعادن *,** ***الجامعة التقنية الوسطى / معهد التكنولوجيا بغداد _yahoo.com5599as@***البريد االلكتروني: ةالخالص يتضمن البحث تحديد الظروف المثالية للحام االنتشاري المباشر للنحاس خالي األوكسجين_ عالي الموصلية مع الصلب المقاوم للصدأ وقد تم استخدام برنامج )5-10*1 (mbrيصل الى ط المعدنين في جو مفرغ من الهواءمختبريا. وقد تم رب )l)304االوستنايتي نوع (minitab16) روف المثلى لربط المعدنين. ومن خالل استخدام البرنامج تم دراسة التاثير المشترك لعوامل الربط على قوة الربط. لمعرفة الظ لمعرفة التركيب (sem-eds)االلكتروني الماسح المجهريه لمنطقة الربط األنتشاري باستخدام المجهر البنيةوقد اجريت فحوصات لمعرفة األطوار التي تكونت في منطقة الربط ومن (xrd)والصالده المايكروية والتحليل الطيفي في منطقة الربط االنتشارالمجهري وعمق يعطي صفات جيده. تم ايجاد الظروف المثلى ااحادي اطوربوصفه (cuni)ن محلول جامد بين النحاس والنيكل خالل الفحوصات تبين تكوّ ميكاباسكال. ولمعرفة قوة الربط تم اجراء فحص الشد ٣٠دقيقه والجهد المسلط كان ٤٥وزمن ربط ٦٥٠◦c حرارةللربط هي عند درجة ان عمق ومقارنة بالنحاس %٦٦٫٥ميكاباسكال وذات كفاءة ربط ١٥٣لمنطقة الربط حيث كانت متانة الربط عند ظروف الربط المثلى تساوي . µm 11.80كان األنتشار الذي تم الحصول عليه في منطقة الربط al-khwarizmi engineering journal al-khwarizmi engineering journal,vol. 12, no. 2, p.p. 124133 (2016) digital image watermarking using arnold scrambling and berkeley wavelet transform iman m.g. alwan* enas muzaffer jamel** *,** department of computer science /college of education for women / university of baghdad *email:ainms_66@yahoo.com **email: enasm.altai@gmail.com (received 26 april 2015; accepted 26 november 2015) abstract embedding an identifying data into digital media such as video, audio or image is known as digital watermarking. in this paper, a non-blind watermarking algorithm based on berkeley wavelet transform is proposed. firstly, the embedded image is scrambled by using arnold transform for higher security, and then the embedding process is applied in transform domain of the host image. the experimental results show that this algorithm is invisible and has good robustness for some common image processing operations. keywords: berkeley wavelet transform, image watermarking, arnold transform, watermark attack. 1. introduction due to rapid distribution of digital files such as text, audio, still images or video over fast communication systems, the plans for verification of digital contents originality and copyright ownership are usually demanded. digital watermarking is a new solution for content protection. it draws significant interests and becomes an active research field [1]. generally digital watermark is the technology of adding verification message or hidden copyright information called a watermark or label or signature to the digital media so that it can be extracted or detected later to make a confirmation about the object [2]. several eligible characteristics should be available in watermarking system. they are imperceptibility, which means perceptual parity between the original and the watermarked images, robustness, which means the immovability of the watermark data against changes and alteration to the watermarked file, and finally capacity, which indicates the amount of information that can be saved in the cover media . to reveal the watermark information, two techniques are followed. they are blind and non-blind techniques. in the first one the cover media is not required while in the second one, the original media is required for extraction. mainly, two alternative watermarking methods exist; spatial and frequency (transform) domains. the spatial domain techniques are not powerful even to the insignificant of altering or removal attempts (attacks), hence these techniques have become less common. on the other hand, the transform domain techniques have taken the most interests by the researchers and almost all of the known transforms have been used [3]. the transforms used are discrete cosine transform (dct), discrete fourier transform (dft), and discrete wavelet transform (dwt) [4,5]. in [3] slantlet transform is adapted in watermarking process, while in [6] the contourlet transform is used as a frequency domain watermarking system. the curvelet transform based logo watermarking is proposed in [7]. in [8] a two-dimensional triadic wavelet transform is proposed, it’s called berkeley wavelet transform. it participates many characteristics like oriented, spatial localization, and frequency bandpass. it is formed by 4-complete, orthogonal bases which the transform and inverse transform computations are fast. its iman m.g. alwan al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 133124(2016) 125 good computation and fine primary simulation visually makes it a robust tool in watermarking process. in [9], the authors proposed a watermarking scheme based on berkeley wavelet transform. the embedding process is carried out in the dc band of the transformed host image only by sub-dividing it into non-overlapping blocks, and replacing the binary watermarked coefficient with only one designated coefficient of middle frequency diagonally, and then an inverse berkeley wavelet transform isperformed to get the watermarked image. this algorithm embeds a limited amount of information since it is embedded in one band which is (1/9) of the total host image size. they used a host image of size (243x243) and the binary watermark image of size (27x27). in this paper, berkeley wavelet transform is used for grey scale image watermarking process, the grey scale watermark image is first scrambled by using arnold transform to boost the security side, and then it is embedded in the whole frequency bands of the transformed grey scale host image. so the amount of embedded information is greater. from simulation results, the proposed method shows good performance in terms of peak signal to noise ratio (psnr) of the watermarked image and normalized correlation (nc) between the watermark image and the extracted one. the performance of the system is also tested under various attacks including noise, jpeg compression, and cropping. the results exhibit a good response of the proposed system. rest of this paper is organized as follows: the concepts of berkeley wavelet transfrom are introduced in section 2. in section 3, the proposed embedding algorithm will be presented. finally, the simulation results and discussion will be given in section 4, followed by the conclusions in section 5. 2. berkeley wavelet transform the berkeley wavelet transform is a wavelet basis, triadic, 2dimensional transform. it presents an effective image representation. its computational prosperities are useful; it is complete, orthonormal, and a sparse code for images of natural type. bwt includes 4pairs of mother wavelets at 4orientations. at every pair, one of the wavelet is odd symmetric, and the other is even symmetric. orthonormal, complete basis in 2dimensions are resulted from the translation and scaling of the total set plus a single constant term of wavelet. the mother wavelets are piecewise constant functions, so each wavelet, 𝛽𝜃 ,𝜙 , can be totally represented as a matrix 𝑏𝜃 ,𝜙 of 3x3 dimensions [8]: 𝑏|,0 = 1 6 −1 0 1 −1 0 1 −1 0 1 …(1) 𝑏|,𝑒 = 1 18 −1 2 −1 −1 2 −1 −1 2 −1 …(2) 𝑏/,0 = 1 6 −1 1 0 1 0 −1 0 −1 1 …(3) 𝑏/,𝑒 = 1 18 −1 −1 2 −1 2 −1 2 −1 −1 … (4) 𝑏−,0 = 1 6 −1 −1 −1 0 0 0 1 1 1 …(5) 𝑏−,𝑒 = 1 18 −1 −1 −1 2 2 2 −1 −1 −1 …(6) 𝑏\,0 = 1 6 0 −1 1 1 0 −1 −1 1 0 …(7) 𝑏\,𝑒 = 1 18 2 −1 −1 −1 2 −1 −1 −1 2 …(8) daughter wavelets βθ,ϕ m,n,s can be produced at various positions (i, j) in the x-y plane, and various scales, (s) through scaling and translation of the mother wavelets βθ,ϕ by using the dilation equation: βθ,ϕ m,n,s = 1 s2 βθ,ϕ(3s x − i , 3s y − j ) …(9) the bwt uses triadic scaling, i.e. the sizes of the daughter wavelets are scaled by powers of 3. to form an orthogonal set, the possible translations in the x-y plane are locked to integer multiples of the wavelet size, 3s. all of the bwt wavelets have zero mean, and so a single dc term is required to represent the mean value of an image: β0 = u(x 3 , y 3) / 9 …(10) note that this dc term is not subject to the dilation equation; instead, it is applied only once, at the largest spatial scale. since the bwt is a complete, orthonormal set, it is self-inverting. an image can be reconstructed from its bwt coefficients using [8]: iman m.g. alwan al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 133124(2016) 126 𝐼 𝑥, 𝑦 = 𝑤𝑚 ,𝑛 ,𝑠𝛽𝜃 ,∅(3𝑠 𝑥 −∞ 𝑚 ,𝑛 ,𝑠=0𝜃∈θ ,𝜙∈φ 𝑚 , 3𝑠(𝑦 − 𝑛) …(11) where wm,n,s θ,ϕ are the bwt coefficients representing the image. figure (1) shows the output of the berkeley wavelet transform of the image boat as it is obtained by the berkeley wavelet transformation program. (a) (b) fig. 1. the original image (a), the transformed image (b). 3. the proposed system the proposed system is based on embedding grey scale visual watermark image of size (1/9) of the host image into the host grey scale image by using berkeley wavelet transform (bwt). for security confirmation and robustness improvement, the watermark image is scrambled before embedding into the host image. arnold transform algorithm is adopted as a scrambling scheme to the original watermark image. arnold transform has periodicity process, so the image can be reclaimed after the permutation concept. it is only appropriate for n×n digital images. it is defined as 𝑥′ 𝑦′ = 1 1 1 2 𝑥 𝑦 mod n …(12) where (x, y) represent the pixel coordinates of the original image, while (x', y') represent the pixel coordinates of the encrypted image. let c indicate the matrix at the left of the right hand side of equation (12), im(x, y) indicate the original image pixels, and i𝑚(𝑥′ , 𝑦′)𝑛 indicate pixels of the encrypted image acquired by n-times arnold transform application. thence, arnold transform’s image encryption is [10]: 𝐼𝑚 𝑥′ , 𝑦′ = 𝐶 𝐼𝑚(𝑥, 𝑦) 𝑟−1 (𝑚𝑜𝑑 𝑁) …(13) where r = 1, 2, ….. n, and 𝐼𝑚(𝑥′ , 𝑦′)0 = 𝐼𝑚(𝑥, 𝑦). to obtain 𝐼𝑚(𝑥, 𝑦)(𝑟−1), the inverse matrix of c can be multiplied at each side of equation (13). this means, the encryption of the encrypted image can be made by computing the equation (14) n-times iteratively. 𝐷(𝑥, 𝑦) 𝑟 = 𝐶−1 𝐷(𝑥′ , 𝑦′)𝑟−1 𝑚𝑜𝑑 𝑁 …(14) where 𝐷(𝑥′ , 𝑦′)(0) is the encrypted image’s pixel, and 𝐷(𝑥, 𝑦)(𝑟) is a decrypted pixel by executing r iterations. figure (2) shows an example of arnold image encryption with n=5 for pepper test image of size (256x256). (a) (b) fig. 2. the original image (a), arnold transformed image (b). for embedding process, the host image should be a power of 3𝑛𝑥3𝑛 where n is an integer number, and the bit stream of the encrypted watermark image is transformed into a sequence wi(1)….wi(l), where l is the bit stream length, and 𝑤𝑖 𝑚 ∈ −1,1 , 𝑚 = 1, … . , 𝐿 . the sequence is used as the watermark. a: watermark embedding process input: host image, secret image, 𝛼 the scaling factor. output: watermarked image. 1. read the host image i(n,n), the watermark image w(m,m). 2. apply berkeley wavelet transform to i(n,n). triadic pattern image decomposition is applied. 3. apply arnold transform to the greyscale watermark image. 4. change the 2-d 8-bit scrambled watermark pattern of size m x m into a binary sequence w = w k k = 0, … . , m2}, where w(k) ∈ 0,1 . then map the watermark information w into a bipolar vector 𝑤𝑖𝑏 = 𝑤𝑖𝑏 𝑘 𝑘 = 0, … . . , 𝑚2 and 𝑤𝑖𝑏(𝑘) is denoted as 𝑤𝑖𝑏 𝑘 = (−1)𝑤𝑖 (𝑘) …(15) where k=0,1,…..,𝑚2 iman m.g. alwan al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 133124(2016) 127 5. embed the binary sequence in the all transformed host image’s subbands according to the formula 𝑊𝑡𝐼𝑚𝑔 = 𝐻 + 𝛼 × 𝑤𝑖𝑏 …(16) where, wtimg is the watermarked image, h is the host berkeley wavelet transformed image, 𝛼 is the scaling factor, lower value of it gives better quality for the watermarked image, and 𝑤𝑖𝑏 is the watermark information stream. 6. apply the inverse of the berkeley wavelet transform to get the watermarked image. 7. end b: watermark extracting process it is assumed that the original image, value of 𝛼, and number of iteration for arnold scrambling technique n, are known for extraction procedure. input: watermarked image. output: watermark secret image. 1. apply berkeley wavelet transform for the watermarked image, to get the transformed subbands. 2. extract the embedded sequence from the all subbands of the transformed image according to the equation: 3. 𝑤𝑖𝑏 = (𝑊𝑡𝐼𝑚𝑔 − 𝐻)/𝛼 … (17) 4. convert the extracted sequence 𝑤𝑖𝑏 into 0, 1 sequence, reconstruct the scrambled mxm watermark image. 5. apply the inverse arnold transform to get the watermark image. 6. end 4. the simulation results and discussion in this part, the simulation parameters settings of the proposed algorithm, the simulation results, and discussion of the results are exhibited. 4.1 the simulation parameters settings the proposed algorithm was implemented and tested on several standard images using matlab version 7.0.4.365, and was implemented with an intel core i7, 2.7 ghz processor. the host images are of size 243x243, and the watermark images are of size 80x80. to evaluate the qualityof the watermarked image, psnr criteria were adopted. greater values of psnr indicate preferable quality of the watermarked image. values of psnr more than 30 dbs denote acceptable image quality, where no significant change is made by watermarking process [10]. the algorithm was also tested under different kinds of signal attack. figure (3a) and (3b) displays the test host, and watermark images. equation (18) represents the peak signal to noise ratio [10]. 𝑃𝑆𝑁𝑅 = 10𝑙𝑜𝑔10( 2552 𝑀𝑆𝐸 ) …(18) 𝑀𝑆𝐸 = ( 1 𝑁 )2 (𝑝𝑖𝑗 − 𝑝𝑖𝑗 ′ )2 …(19) where 𝑝𝑖𝑗 ’s stand for the values of the original pixel, 𝑝𝑖𝑗 ′ ’s stand for the values of the modified pixel, and n is the image dimension. the efficiency of the watermark extraction result is evaluated by using normalized correlation coefficient (nc), for the extracted watermark w' and the original watermark w as: 𝑁𝐶 𝑊, 𝑊 ′ = 𝑤 𝑖 𝑤 ′ (𝑖)𝑛 𝑖=1 𝑤(𝑖)2𝑛 𝑖=1 𝑤 ′ (𝑖)2𝑛 𝑖=1 …(20) where (n×n) are the watermark dimensions. the unity value given exact matching between the extracted watermark and the original watermark images, nc of about 0.7 or above is counted passable [11]. iman m.g. alwan al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 133124(2016) 128 a. test host images. b. test watermark images. fig. 3. test host and watermark images. 4.2. the simulation results the simulation results of the proposed algorithm are shown in figure (4). it shows the watermarked images and the reconstructed watermark images. psnr values of the watermarked images are also included. the normalized correlation (nc) is listed to indicate the similarities between the original watermarks and the extracted ones. psnr= 40.88 db psnr=40.66 db psnr=40.87 db psnr=40.7 db nc=1 nc=1 nc=1 nc=1 fig. 4. the watermarked images and the reconstructed watermark images. iman m.g. alwan al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 133124(2016) 129 various attacks are used to test the robustness of the watermark algorithm, such as noise (gaussian, salt & pepper), geometrical distortion (cropping), and jpeg compression. figure (5) shows results of applying various attacks to the watermarked test image. psnr= 25.22 db salt & pepper noise gaussian noise mean=0, variance=0.00005, psnr= 32.37 db crop 1/9 of image psnr=15.12 db jpeg compression 30% psnr= 32.94 db nc= 0.8404 nc=0.8071 nc=0.6241 nc=0.8043 psnr= 25.01 db salt & pepper noise gaussian noise mean=0, variance=0.0005 psnr= 34.84 db crop 1/9 of image psnr= 16.48 db jpeg compression 30% psnr= 30.99 db nc=0.8950 nc=0.8071 nc= 0.8293 nc= 0.7491 psnr = 24.90 db salt & pepper noise(0.01) gaussian noise mean=0, variance=0.00005 psnr= 35.58 db crop 2/9 of image psnr= 12.93 db jpeg compression 30% psnr = 36.44 db iman m.g. alwan al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 133124(2016) 130 fig. 5. results of applying various attacks to the watermarked images. the results of the proposed algorithm were compared with [10] in which non blind digital image watermarking based on discrete wavelet transform has been proposed. the watermark image was encrypted by arnold transform and cross chaotic sequence, the encrypted watermark image is transformed into wavelet transform domain, and the medium frequency coefficients are extracted and embedded into the wavelet transformed host image. figure (6), shows the psnr and nc of both algorithm in [10] and the proposed one respectively. fig. 6. psnr and nc of both algorithms in [10] and the proposed. nc= 0.7631 nc=0.6527 nc= 0.5391 nc= 0.7635 psnr= 27.68 db salt & pepper noise(0.004) gaussian noise mean=0, variance=0.0005 psnr= 31.85 db crop 3/9 of image psnr= 8.14 db jpeg compression 30% psnr= 30.99 db nc=0.8950 nc=0.6642 nc= 0.4417 nc= 0.7930 results of algorithm in [10] results of the proposed algorithm psnr=33.243db. psnr=40.66 db iman m.g. alwan al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 133124(2016) 131 4.3. the discussion the simulation results show that the proposed algorithm offers good response in terms of quantitative parameters (peak-signal-to-noise ratio and normalized correlation) and in terms of visual quality. from figure (4), the values of psnr of the watermarked images are between (40.6640.88) db for the test images which is perfectly convenient for the human eyes since values of psnr greater than 30 dbs indicate convenient image quality. also the extracted watermark test images have normalized correlation values of one which means exact similarity between the original and the watermarked images. the inviolability of the watermark versus remove or degradation attempts by attacks of different digital signal processing operations like noise (gaussian, salt & pepper), different rates of geometrical distortion (cropping), and jpeg compression is measured by nc criteria. from the results of figure (5), it is seen that watermark can be still extracted despite the degradation of image quality due to different types of attacks. also from figure (6), it can be noticed that the proposed algorithm offers better imperceptible results. the improvement in the psnr value for boat image is 7.417 db. 5. conclusion in this paper, a non-blind digital image watermarking scheme is proposed. it depends on using berkeley wavelet transform (bwt), which is a complete orthonormal basis functions. the watermark image is firstly scrambled by arnold transform to achieve higher embedding security. the embedding process is done in the whole frequency subbands of the transformed host image. the evaluation of the proposed method in terms of psnr and normalized correlation shows very good performance as far as invisibility. also the proposed method offers good response under various image attacks. notation bwt berkeley wavelet transform h host image in bwt domain im(x,y) original image pixel im(x′, y′)n pixels of encrypted image acquired by ntimes arnold transform. mse mean square error nc normalized correlation psnr peak signal to noise ratio wtimg watermarked image w(m,m) watermark image greek letters 𝛼 scaling factor β0 dc term of bwt βθ,ϕ m,n,s daughter wavelet of bwt wm,n,s θ,ϕ bwt coefficients 6. references [1] ramani k., prasad e.v., naidu v.l., and ganesh d.,”color image watermarking biorthogonal wavelet transform”, international journal of computer application, vol.11, no.9, pp. 25-29, december, 2010. [2] ram b., “digital image watermarking technique using discrete wavelet transform and discrete cosine transform”, international journal of advancements in research & technology, vol. 2, no.4, pp.1927,april-2013. [3] lafta m.m. and alwan i.m.,” watermarking in image using slantlet transform”, iraqi journal of science, vol.52, no.2, pp. 225230, 2011. [4] bailey k., curran k.,” an evaluation of image based steganography methods”, multimedia tools & applications, vol. 30, no. 1,pp. 55-88,july 2006. [5] gutub a., fattani m.,” a novel arabic text steganography method using letter points and extensions”, waset international conference on computer, information and system science and engineering, vienna austria, may 25-27, 2005. [6] taiyue w., hongwei li.,” a novel scrambling digital image watermarking algorithm based on counterlet transform”, journal of natural science, vol. 19, no. 4, pp.315-322, 2014. [7] hien t.d., miyara k., nagata y.,nakao z., and chen y.w.,” curvelet transform based logo watermarking”, innovative algorithms and techniques in automation, industrial electronics and telecommunications, pp 305-309, springer 2007. iman m.g. alwan al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 133124(2016) 132 [8] willmore b., prenger r.j., wu m. c-k, and gallant j.l.,” the berkeley wavelet transform: a biologically-inspired orthogonal wavelet transform”, mit press journals, neural computation, vol. 20, no.6, pp. 1537-1564, june 2008. [9] ravindran r. p., soman k.p.,” berkeley wavelet transform based image watermarking”, international conference on advances in recent technologies in communication and computing, india, pp. 357-359, 2009. [10] pradhan c., raths. and kumar bisoi a. , ” non blind digital watermarking technique using dwt and cross chaos”, 2nd international conference on communication, computing, and security, india, procedia technology, elsevier ltd., no.6, pp. 897-904, 2012. [11] pan j.s., huang h.c., and jain l.c., ”intelligent watermarking techniques”, world scientific publishing co. pte. ltd., 2004. (2016) 133124، صفحة 2، العذد12دجلة الخىارزمي الهنذسية المجلم ايمان محمذ جعفر 133 berkeley waveletو تحىيلة arnoldالعالمة المائية الرقمية بإستعمال تحىيلة **ايناس مظفر جميل* جعفر علىان ايمان محمذ جاهعت بغذاد / كليت التزبيت للبٌاث / قسن الحاسباث** ,* ainms_66@yahoo.com :البزيذ األلكتزوًي* enasm.altai@gmail.com:البزيذاأللكتزوًي** الخالصة يقذم هذا البحث خىارسهيت و تعزف عوليت تضويي البياًاث في وسط رقوي كولف الفذيى, أو الولف الصىتي , أو الصىرة بالعالهت الوائيت الزقويت arnoldفي هذٍ الخىارسهيت الوقتزحت يتن اوال تشفيز الصىرة السزيت باستعوال تحىيلت . berkeley waveletالعالهت الوائيت التي تعتوذ علً تحىيلت أظهزث الٌتائج العوليت جىدة هذٍ الخىارسهيت الوقتزحت وهتاًتها . هي ثن تٌفذ عوليت االخفاء في هجال التحىيلت للصىرة الوضيفتو, لتحقيق هستىي أهاى أعلً . عالجت الصىريتلبعض عولياث الن chapter two al-khwarizmi engineering journal al-khwarizmi engineering journal,vol. 12, no. 3, p.p. 8098 (2016) experimental study using the passive solar chimney for evaporative cooling with pcm and cfm as a thermal energy storage talib k. murtadha* hussien m. salih** ali d. salman*** *department of mechanical engineering/ university of technology **,***department of electromechanical engineering/ university of technology *email: talib_km@yahoo.com ** email: hussein_maj@yahoo.com *** email: aligaphory@yahoo.com (received 11 january 2016; accepted 17 april 2016) abstract in this work, a test room was built in baghdad city, with (2*1.5*1.5) m 3 in dimensions, while the solar chimneys (sc) were designed with aspect ratio (ar) bigger than 12. test room was supplied by many solar collectors; vertical single side of air pass with ar equals 25, and tilted 45 o double side of air passes with ar equals 50 for each pass, both collectors consist of flat thermal energy storage box collector (tesb) that covered by transparent clear acrylic sheet, third type of collector is array of evacuated tubular collectors with thermosyphon in 45 o instelled in the bottom of tesb of vertical sc. the tesb was made from metallic iron sheets as a shell and fuelled by paraffin wax as phase change material (pcm). the pcm supported by copper foam matrix (cfm) to enhance thermal conductivity of wax. when heat is released from tesb to the air, a buoyancy force will be generated in chimney gaps. then a difference in pressure between inside and outside test room leads to induce the air flow to test room through wet corrugated cellulose pad, where evaporative cooling (ec) occurs. results of experimental work, that achieved in june, for 12 to24 hour in the test day, refer to effectiveness using ec to decrease the room temperature comparing. the system reduces test room temperature of up to 8.5~9.2 o c in 11:00 am to 3:00 pm and at highest effectiveness of ec, while minimum reduces in temperature of up to 3.5 o c in 8:00pm to 3:00 am. also, the results showed the affectivity to using the tesb, during the night time for ventilation and ec, with lower effectiveness than from day time. the range of ec effectiveness equals 30.5-37.5 with a natural vent, while the maximum air change per hour (ach) equals (3.8-6.187), and the maximum mass flow rate is equal to (36.651 kg.hr -1 ) at experimental evaluation of the system’s discharge coefficient value 0.371. key words: solar chimney , evacuated tubular collector, phase change material, copper foam matrix. 1. introduction the energy consumed for space air conditioning, for heating or cooling and ventilation, depends on the latitude and altitude of the building. the consuming of energy dose not only lead to deplete energy source in our planet, but also lead to release more amount of co2. so, that increases the globe worming potential and leads planet to creasy weather, beside increasing in temperature. many sources are available and can be employed as renewable clean energy. and, solar of the sun is one of the important sources. so, many researches and studies have been employed to use the sun energy for cooling and ventilation, not for human comfort only, but in the industrial and agriculture. maerefat [1] studied the sc and earth to air heat exchanger (eahe) to decrease the indoor temperature. results showed that the performance of the system depends on the solar radiation, outdoor air temperature , beside the configuration between sc and eahe. with a taller sc in use, the number of required scs decreases. other side employed taller scs lead to uncomfort. same study was hinted for the optimum eahe design for 0.5 meter in diameter and 20 meter in length. maerefat [2] numerically studied for a combined system employing a sc with evaporative cooling cavity (ecc). results revealed that the integrated system led to good conditions at daytime in test room, even mailto:talib_km@yahoo.com mailto:hussein_maj@yahoo.com talib k. murtadha al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 8098 (2016) 81 at high ambient air temperature about 40 o c, with low solar intensity of 200 w/m 2 , and relative humidity of 50%. ventilation rate influenced by ambient temperature and solar intensity and configuration between both sc and ecc. wasfy [3] work, a simulation performance of ventilation and evaporative cooling was studied in hot dry climate, for simulating test room in baghdad city. room was supplied by sc from one side, and wet pad from other. results showed the ability to decrease the temperature inside the room to 10 degrees c, in hot dry climate, where the face of sc oriented to the west. poshtiri [4] made comparison between two systems (sc-eahe and sc-ecc). numerical experiments showed that the sc-ecc system can prepare good indoor conditions, at low relative humidity of ambient air, and cooling demand of the room. also, it depicted that the system can provide a good thermal condition after sun set. other type sc-eahe system results refer to that, at high ambient temperature and cooling load, system can provide a good indoor condition even at high air temperature and low solar intensity. presented a comparison between two systems limited the ability to use the sc-eahe for low insulation building, while the best choice for scecc system is with high insulated building, especially in dry climates. hassan [5] showed results of a case study in assiut city, for sc and evaporative cooling. results showed the effect of air flow rate, by the relation between solar radiation, pressure coefficient with area of solar collector. air flow rate increased when collector's temperature increased, the test room temperature decreased by 10-11.5 o c from the outdoor temperature, in the test day 21may-21 august. mizanur [6] presented an experimental work, applied a new design of passive solar chimney with a modern configuration of ec. where the air induced through the sc leads the outside hot air to pass through the pipe that immersed in outdoor splash water pool. for manipulated air, the temperature decreased approximately 5 o c below the ambient temperature, and about 2-3 o c below the room temperature. fazel [7] produced a new configuration of passive cooling system through ventilation mode. the system reduces test room temperature of up to 5 o c from the atmospheric temperature, with ability to decrease room temperature during night ventilation. 2. experimental set up 2.1. rig set-up the rig that used in this work consists of insulated test room, two types of solar chimneys (sc) that joint together in series configuration; a vertical fixed sc, and tilted one with 45 o in angle, both instilled at the south oriented wall. as well as evacuated tubular collectors with thermosyphos array are used. good accuracy measurement instruments tools are used in different measuring, beside two types of data acquisition data logger daq. 2.1.1. semi full scale test room and the effective dimensions of the system the test room with dimensions (2m length, 1.5 m width, 1.5 height), supported by sc’s in the south oriented wall, while paper fill (pad) inserted inside vent window and covered by wind protection in north oriented wall. the length of room is bigger than from width and height, to clarifying the behavior of temperature distribution inside room. the structure of test room consists of a wooden frame, walls are insulated by 4 cm of cork with 0.043 w/m. k in thermal conductivity, 2.5 cm thick with 0.05 w/m. k for glass wool. the outside walls are insulated by marmox with u=2.7 w/m 2 .c, while the roof and floor are insulated by marmox thermo-block with u=1.69 w/m 2 . o c. fig.1, shows ec paper fill (pad), fig.2. depicts room general details in iso view, and fig.3, shows the etc with characteristics given in table.1. fig.4. describes the schematic diagram for the test room in vent and ec-mode, that provided with two types of solar collectors instrumented with number of velocity and temperature sensors, table.1, defines all the symbols of fig.2. 2.1.2. evacuated tubular collectors (etcts) ten pieces of etc with thermosyphon (etcts) are used to collect heat at an inclination angle of 45 o , and transfer heat to the bottom of the vertical sc. etc 50 cm in length and 5.8 cm in diameter is shown in fig.3. ts consists of the condenser which instilled inside the tesb, ts’s evaporator is inserted in the axial center of double glass etc and covered by thin aluminum fin. expander tube with expander roll tools are used to make a good contact between ts’s condenser and (cfm) in tesb. talib k. murtadha al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 8098 (2016) 82 fig.1. vent open window covered by pape fill in evaporative cooling mode fig. 2. schematic diagram of insulated test room. cellulose pad weather station (isoview) θ c=12 cm ac o l1 a=180cm *18 cm wind protection inlet air wind protection l h w cw aci ac o ari lo1 w1 hade chimney protection 1ɵ s1 d1 d2 inclination angle inlet air (vent air) outlet air (exhaust air) si stack height si cellulose pad splash water etcts base splash water path cellulose pad water tank wind protraction talib k. murtadha al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 8098 (2016) 83 table1, description of symbols shown in fig. 2 . fig. 3. evacuated tubular collector with description notes. 0.75 meter in width. the box filled by copper foam matrix (cfm), and full refined paraffin wax, to form a thermal energy storage. upper half of box is covered by double acrylic clear glass from outside, lower halve part is thermally insulated, and connected to ten evacuated tubular collectors, of 50 cm length tilted at 45 o . the upper side of tesb that exposed to the sun light is painted by a thermally matt black paint. the other side of the storage box (room side) is covered by a acrylic sheet, with 6.7 cm gap space and 14.92 in aspect ratio. fig.5. shows steps for manufacture the vertical fixed solar chimney. imension description symbol no dimension description symbol no 6.7 (cm) chimney gap cg 12 148 (cm) width of the test room w 1 (thick=2.7cm* w=75cm*h=10 2cm) thermal heat storage box ths-b 13 147 (cm) high of the test room h 2 (75m*11cm) area inlet to the chimney aci 14 200 (cm) length of test room l 3 (75cm*8cm) area outlet from chimney aco 15 75 (cm) chimney width (thsbw) cw 4 (148cm*16) area inlet test room ari 16 150 (cm) second system chimney height l1 5 ( o c) inside temperature tthsb-i 17 91 (cm) head chimney protection width w1 6 ( o c) surface temperature tthsb-s 18 90 ( o ) head chimney protection angle 1ɵ 7 ( o c) covered surface temperature tthsb-sc 19 20 cm head chimney protection side length s1 8 ( o c) temperature air inlet chimney gap tair-in-c 20 4.5 (cm) head chimney distance between lower side corner and exit of moved chimney d1 9 ( o c) temperature air outlet chimney gap tair-out-c 21 18 (cm) head chimney distance between top corner and exit of moved chimney d2 10 12 cm wind protection space from window c 22 115 (cm) height from ari to the base lo1 11 1 thermosyphon evaporator 4 black absorption inner layer 2 thermosyphon condenser 5 fin of evaporator 3 vacuum insulation tube 6 centering tube stopper 3 5 6 4 2 1 talib k. murtadha al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 8098 (2016) 84 fig. 4. schematic diagram describing the test room in vent and evaporative cooling mode. 2.1.3.the solar chimney (sc) two systems of solar chimneys are used, in ventilation with evaporative cooling mode: a-a vertical fixed solar chimney system vertical built-in chimney for ventilation and ec mode. a one meter in height of galvanized iron box collector installed at the south oriented wall with 0.75 meter in width. the box filled by copper foam matrix (cfm), and full refined paraffin wax, to form a thermal energy storage. upper half of box is covered by double acrylic clear glass from outside, lower halve part is thermally insulated, and connected to ten evacuated tubular collectors, of 50 cm length tilted at 45 o . the upper side of tesb that exposed to the sun light is painted by a thermally matt black paint. the other side of the storage box (room side) is covered by a acrylic sheet, with 6.7 cm gap space and 14.92 in aspect ratio. fig.5. shows steps for manufacture the vertical fixed solar chimney. b-a tilt solar chimney system inclined sc at 45 o is used by combining with the fixed vertical chimney system. tilted sc consists of a three tesb made from iron galvanized boxes that painted by a layer of matt black and filled with cfm and semi refined of paraffin wax as pcm. the three boxes are arranged in series configuration along the length of sc and construct a double side chimney gap, with 3 cm in each gap wedth. evacuated solar collector thermosyphon evaporator of thermosyphon condenser of thermosyphon n :north direction s :south direction ec mode series chimney working angle pcm 1pcm 1pcm 1? flat box collector consist from rectangular flat galvanized iron boxes contain mf-pcm inside it. mid cmf-pcm collector -double parallel air flow channel up and down the mf-pcm in flat box collector natural evaporative cooling ratio of length to the depth 2*(l/g=50) -high =length cos(theta) wind protection wind protection water tank glob valve splash water paper fill clear acrylic cover  talib k. murtadha al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 8098 (2016) 85 cfm flat plat box constrict the tesb sc gap array of etc collector of fixed chimney acrylic wall tesb etc base step-1 step-2 step-3 step-4 step-5 fig . 5 stages to manufacture the vertical fixed sc and setup in the test room. outline dimensions for tilted sc are 1.5 m in length and 0.75 m in width as shown in fig .6,the schematic diagram is shown in fig .7. sc’s boxes covered by 0.4 cm of acrylic clear sheet. tilt chimney test room tesbs tilted chimney chimney gap solar collector etcts cross section in tilted sc tc location transparent acrylic cover vertical fixed sc fig . 6 setup the inclined sc in the test room talib k. murtadha al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 8098 (2016) 86 induced air flows through a duple pass over flat thin tes box mid collector, with 50 in aspect ratio for each pass, and that bigger than the critical aspect ratio (arcr=12), to prevent back flow. 2.2. solar chimney components 2.2.1. the solar chimney type and working angle in selective mode in this study, an experimental and theoretical examination are applied, to select the active working angle for tilted sc. right angle means a good contact between air flow and sc collector without separation, but this angle conjugating simultaneously with low solar intensity. experimental result, beside theoretical fig.10 program simulation result refer to choice angle, at 45 o as selective working angle in this study. also in this work, experimentally examining covers three types of inclined 45 o scs; (flat plate, flat plate with double pass, flat thermal energy storage box with double pass). all testes applied for vent mode only. results in fig.11 refer to the ability of flat plat collector with double pass, to release heat to air, but with no effect in night time, so flat box collector with double pass is the active sc collector to employing in vent and ec mode. 2.2.2. the absorber one tesb are used as sc collector in vertical chimney, while three tesbs are used to construct the tilted chimney collector. the emissivity of the painted layer of plate is ε=0.095. and the absorptivity αp=0.9, while the reflectivity ρplate=0.1. 2.2.3. thermal energy storage material a combined of paraffin wax, as a phase change material, and copper foam matrix are used as a tesm. where the paraffin wax is used to storage heat, in sensible and latent heat regions, while the cfm is used to enhance the thermal conductivity of thermal tesm . air inlet to the first sc pass air inlet to the second sc pass temperature sensor probe for air temperature sensor probe on plate or built in material velocity sensor position th e ta flat plat collector with matt black paint 38 39 40 42 37 acrylic sheet 4mm tc.probe insulation (wall glass) 2 in, 24 kg/m3 in density serface tc probe inlet air temperature probe outlet air temperature probe temperature of acrylic sheet 25 cm 50 cm 50 cm 25 cm iron galvanized 0.8mm z=1.2 cm z=1.8 cm z=2.4 cm z=3.6 cm z=4.2 cm z=4.8 cm z=5.4 cm z=6 cm z=3 cm z=0.6 cm 43 46 49 52 58 61 64 67 44 47 50 53 59 62 65 68 45 48 51 54 60 63 69 71 70 72 (p cm+cfm) (pcm+cfm) iron galvanized matt paint box (p cm+cfm) (p cm+cfm) 73 57 75 66 74 distance between transparence sheet and tesb collectors was 3 cm, amd between tesb and the base of sc was 3cm. talib k. murtadha al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 8098 (2016) 87 table2, n-alkenes table no. n-alkanes no of carbon mol. weight melting point (k) latent heat of fusion (kj/kg) density at 20 o c (kg/m 3 ) specific heat boiling point (k) solid (j/mol.k) at 298 k liquid (j/mol.k) at 353 k 1 heneicosane 21 296 313.35 213 788 (s) 570.7 a 698 a 629.7 2 docosane 22 310 317.15 252 791(s) 598.1 a 739.0 641.8 3 tricosane 23 324 320.65 234 793(s) 625.0 a 772.0 653.4 4 tetracosane 24 338 323.75 255 796(s) 651.4 a 805.0 664.5 5 pentacosane 25 352 326.65 238 798(s) 670.4 a 815.9 675.1 6 hexacosane 26 366 329.45 250 800(s) 677.8 a 870.0 685.4 7 heptacosane 27 380 331.95 235 802(s) 728.1 a 928 a 695.3 8 octacosane 28 394 334.35 254 803(s) 752.8 a 937.0 704.8 9 nonacosane 29 408 336.35 239 805(s) 777.2 a 1001 a 714.0 a:estimated values-experimental data not avilible time (sec) t e m p e ra tu re (c ) 0 100 200 300 400 500 600 700 56 57 58 59 60 61 62 63 64 65 time (sec) t e m p e ra tu re (c ) 0 200 400 600 800 1000 1200 1400 1600 44 46 48 50 52 54 56 58 60 62 64 66 2.2.4. phase change material (pcm) many types of paraffin and microcrystalline wax are examined to find the suitable wax. so two types of paraffin wax are selected as working pcm; -first type a full refined paraffin wax pw-600, used as a tesm with a cfm. this type is used in the fixed vertical sc. -second wax type is a semi refined paraffin wax, used with the cfm as a tesm in the tesb for the second inclined chimney. to define the thermo physical properties of each wax, by limiting the melting point for each experimentally from (temp-time) diagram fig.8. then by using empirical relations that dependent on the number of carbons. where from the melting temperature and from table-2 [8], can be select the suitable wax, then calculated the properties for solid, liquid single zone and mushy zone. the formula defined n-alkanes structure is , n means the number of carbons. fig. 8. experimental results show behavior of wax in different temperature a, full refined pw b, semi-refined pw talib k. murtadha al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 8098 (2016) 88 fig. 9. copper foam matrix a-with pw, b-without pw. 2.2.5. copper foam matrix (cfm) the combined of fm-pcm means higher thermal conductivity, with same latent heat of fusion, and same solidification and melting temperature. so, a copper foam matrix cfm is used to enhance the heat transfer, because the thermal conductivity of pcm is not enough to receive or release heat in selective heat transfer duration time. fig .9, refers to the cfm with and without pcm. cfm used with 95% porosity and 30 porous per inch (30 ppi). 2.2.6. the transparent cover nontraditional transparent cover, 4 and 6 mm from clear acrylic sheets are used with vertical and tilted 45 o scs. the special properties for these material are the; flexibility, light weight, anti crash, beside other properties that in common with bk-7. all important properties for acrylic and bk-7 except thermal conductivity of bk-7, are calculated for three selective angles and listing in table.3, that showing a comparison between commercial glass sheet (bk-7) and clear acrylic sheet. 2.3. measurement and instrument tools the following measurement and instrument devices are used in this project beside data logger, data acquisition (daq), to measuring the depended and independent variables; 2.3.1. temperature three types of temperature sensors are used in different positions. with 290 meter of type-k thermocouple (tc) are used to cover all the temperature that must be measured in the sc’s and test room beside the sc’s gap. a 3d mesh grid of temperature sensors are distributed inside table 3, physical properties for acrylic and commercial window glass( bk7). angle (degree) n ƙl k (w/m. o c) glass bk7 30 1.526 0.799 0.072 0.125 32*l at 4mm 0.92 0.81 45 0.782 0.0875 0.133 60 0.729 0.14 0.141 clear acrylic 30 1.491 0.885 0.0741 0.0414 0.04 0.94 0.7 45 0.872 0.0868 0.0443 60 0.82 0.143 0.0477 l: cover thickness in mater. n: average refractive index in solar spectrum of cover materials. ƙ: extinction coefficient + + =1 = transmitivity, ρ=reflectivity = absorbtivity, = emissivity (a) (b) 40 -x 40 -x talib k. murtadha al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 8098 (2016) 89 the test room. 36 semiconductors type lm-35dz, with 36 thermocouple probes are distributed inside the room in three horizontal layers (3*4) node. the probes are connected to two types of data acquisition (daq) from labjack u6-pro and ut-7, also two types of digital thermometer are used dm6801a+ digital thermometer with 0.1 o c in resolution and -50 to 199 o c in range, with +/(0.2%+1 o c) value in accuracy. dm6803a+ digital thermometer with 0.1 o c in resolution , 0 to 800 o c in range, and accuracy with +/(0.3%+1 o c). both thermometers are connecting to the selector switch. as well as, array of thermocouple probes are distributed and connected to the vertical and tilted sc’s gab. tc’s probes connected to the collector plate, tesb, etc and glass cover. fig .7 shows the positions array of thermocouple probe sensors in tilted sc. 2.3.2. air velocity two types of a thermal digital anemometer with high resolution are used to measure the air velocity in the two systems of chimney gap, beside room. -tsi avm410 thermal anemometer with 0.01 m/s in resolution, and same value in threshold. velocity range (0 to 20 m/s), and reading temperature range (-18 to 93 o c). -testo 405-v1 thermal anemometer with 0.01 m/s in resolution and threshold, while velocity range (0 to 5 m/s) at (-20 to 0 o c) and (0 to 10) when temperature range (0 to 50 o c). am-4838 digital fan anemometer is used primary to limit the direction of air flow inlet to or outlet from the solar chimney beside smoke generator. the specification of this digital anemometer : 0.1 m/s in resolution, 0.4-30 m/s in range and threshold equals 0.4 m/s. positions of the measured velocity are showed in fig.7, where a three-hole port to measure the velocity from upper side air pass, and two from lower side are pass . 2.3.3. solar radiation intensity two types of solar intensity meter are used in the experimental work. tes1333 model is fixed at tilted sc, with specification: 1 w/m 2 in resolution, 0-2000 w/m 2 in range. other type tes-132 with a data logger and interface connection to pc. its specification: 0.1w/m 2 in resolution and measuring range 0-2000 w/m 2 . this type is used to measure the solar intensity before and after the acrylic cover to calculate the transmitivity value. beside recording solar intensity on surface of etc and fixed sc. average solar intensity recorded by ws. 2.3.4. weather station system a modern weather station model ws-1000wifi with 915 mhz in frequency, outdoor and indoor instrument collection, transmitted the data every 16 second to the analyzer data logger data screen, with built in memory, and external data storage. data logger records the data transmitted at interval time, that recognized by user to record data each 60 seconds for 24 hour. the following important data can be recorded by the ws-1000wifi :  indoor average temperature  indoor relative humidity  real and absolute pressure  outdoor average temperature  outdoor relative humidity  solar radiation intensity (horizontally)  wind speed  gust speed  wind direction 2.4. experimental test procedure the experimental work, is achieved in june, 2015, where data are logging for the dependent variables along 12 hours. all measurement and instruments tools are used as mentioned previously to measure and record the dependent variable, for each 2 hours as test interval, and average value for general variables that measured and recorded by ws data logger along 24 hours, with 20 minutes as test interval the depended variables including each of measuring temperature in; chimneys gap, test room space, tesb, outdoor temperature, velocity in chimney gap beside inlet and outlet sc solar intensity. while the general depended variable including each variables that measuring by ws. many conditions are applied, to select test day such as; clarity (not dusty), acceptable wind speed without gust, the clouds absence or partial cloudy day. talib k. murtadha al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 8098 (2016) 90 2.5. theoretical consideration and calculation in this study assuming there is no heat losses directly from test room to the surround, or from the insulated parts of sc’s. therefore, sc that exposure to the sun solar, absorbed all heat with respect to the value of collector absorbtivity, reflectivity and emissivity, beside the acrylic cover’s transmitivity, absorbtivity, reflectivity and refractivity value. so, according to the heat balance, heat absorbed by collector must be equal to heat released to the working air that passes through the chimney gap. 2.5.1. calculated heat storage (tesb) in experimental test, results are shown in fig.8, to find melting point range, then from n-alkenes table-2 [8], to define the latent heat of fusion vale in mushy zone. so for material which has a symmetrical distribution of the specific heat for the melting region[9], ...(1) ...(2) ρ ρ ( ) ( ) ...(3) . / . | | / , ...(4) ρ ( ( ))) ( ) as defined before, for materials which show a symmetrical distribution of the specific heat for the melting region. . ..(6) ( ) 2 0 ( )13 ( ) ...(7) ( ) 0 ( )1 ...(8) ( ) ( ) ( ) ( ) ..(9) to calculate heat transfer in evaporative cooling procedure [10]. cooling and humidification (removed heat (sensible) with the addition of moisture (latent)) are: ..(10) ̇ { ( ) ( )} ..(11) 2.5.2. heat transfer to the humid air the inside solar chimney heat transfer from tesb to the moist air by simple equation is illustrated below [10]. ( ) ..(12 ) for the sensible heat transfer to the dry air, ( ( )) ..(13) or by employing the equation of state for moist air [10]. 2.5.4. simultaneous efficiency to compute the simultaneous efficiency at duration time of heat charge, it must compute the rate of heat storage in tesb during its exposure to the solar radiation which can be calculated from eqn. below [8] = ( ) m= mass for wax and copper foam matrix t= duration time to charge tesb by heat (q) so, the heat storage in duration time t can be found from eqn. (15) ..(15) to compute heat storage during duration charge for n time , by algebraic summation of eqn. 14 to get ∑ * + ..(16) its mean the rate between heat storage to the heat absorbed by tesb. , [ ] 0 ⁄ 1 , , talib k. murtadha al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 8098 (2016) 91 = * + ..(17) 2.5.5.ventilation air change per hour (ach) to calculate the mass flow rate through the solar chimney only, or through the solar chimney and room. [11],[12]. √ ( ⁄ ) √ 0 1 ..(18) where, is the system’s discharge coefficient, is defined as the ratio of the crosssection area at the vena-contract to the actual opening area. it is taken as 0.57 due to the sharp edge inlet, or calculated as shown later . is the mean temperature of air in the channel (kelvin), which is described by the equation below [13]. ( ) ..(19) where, is meant for the mean temperature approximation which depends on the inlet and outlet air temperature . , are equal temperature of air inlet and outlet solar chimney; room temperature; ⁄ [14] glass side ...(20-a ) absorber side ...(20-b) ...(21) to calculate the system’s discharge coefficient [15]: | | ...(22) ( ); ( ) ( ) ( ) ( ) ; to calculate ach; air change per hour [14] is ̇ ( ) 3. result and discussion experimental results showed, the effect of ec system by using induced air through solar chimney. fig.12. shows that there is a decreasing in indoor temperature along test time comparing with outdoor temperature. maximum difference in temperature 8.5-9.2 o c occurred at maximum solar radiation with increasing in relative humidity. fig.13. shows the vent-mode only where indoor temperature is almost higher than outdoor temperature with low rh%, especially in noon time at high solar radiation. fig.14. appears the effect of induced air through solar chimney, and the evaporative cooling effectiveness (ece) value, where the high value of effectiveness occurs approximately at high value of solar radiation. that means a high velocity of air through sc (through test room) at noon time. temperature distributions in vertical mid layers along test room are shown in fig.15-(a-i). fig.15-d. shows 3d test room in three layers : east , mid and west layer along the test room and after 2.pm, the sun direction effect is shown in the west layer, where increasing in temperature more than the temperature of east layer. after sunset starts, fig.15-f. shows the starting decrease in room temperature. other fig.15.(g-i) represents the distribution of temperature in test room along day time and night time, where temperature increasing in the roof and near the solar chimney, while it decreases on other zone especially near the wet pad. in fig.16, the experimental and theoretical value of air change per hour (ach) in ec-mode depends on discharge coefficient of system 0.371, that calculated for the present test room. low cd value caused by the effect of fill pad air flow resistance. in experimental work, ach was determined, depending on the tilt sc collector temperature and air velocity, so it measured in mid way in chimney gap, and before the end way of chimney gap. the fluctuation appeared in ach value because of the turbulent in air flow, while the value of theoretical ach was determined depending on the variables in eq.23. the variables change smoothly especially temperature of room and collector, while the calculation of mass flow rate of air depends on upper and lower collector temperature and density. so the air mass flow rate was experimentally estimated in upper and lower chimney gap way (mid ,before end), fig.17. talib k. murtadha al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 8098 (2016) 92 fig. 10. optimal solar chimney angle, for different seasons in baghdad city. fig.11. comparison between three different types of tilted solar chimney's collector with selective working angle. fig. 12. average temperature for indoor and outdoor through test day with vent and ec effect. jan feb m ar apr m ay jun ju l aug sep o ct nov dec fivtenth of month along the year -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 a n g le ( d e g re e ) solar declination angle solar altitude optimum tilt collector angle 8:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 0:00 day time (hh) 24 30 36 42 48 54 60 66 72 78 84 90 96 co lle ct or s ur fa ce te m pe ra tu re ( c ) collector up surface temperature single pass flat plate collector double pass flat plate collector double pass flat storge box collector selective angle for tilted chimney (theta=45 degree) 0:0 0 1:4 0 3:2 0 5:0 0 6:4 0 8:2 0 10:0 0 11:4 0 13:2 0 15:0 0 16:4 0 18:2 0 20:0 0 21:4 0 23:2 0 1:0 0 day time (hh:mm) 26 28 30 32 34 36 38 40 42 44 ai r t em pe ra tu re d eg re e (c ) 12 16 20 24 28 32 36 40 44 48 r el at iv e h um id ity (% ) 11-6-2015 evaporative cooling with splash water 0 100 200 300 400 500 600 700 800 900 h or iz on ta l s ol ar in te ns ity ( w /m ^2 ) 3 4 5 6 7 8 9 10 (t ou t-t in ) d eg re e (c ) indoor temp. outdoor temp. indoor rh% outdoor rh% h solar intensity tout-tin talib k. murtadha al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 8098 (2016) 93 0:0 0 1:4 0 3:2 0 5:0 0 6:4 0 8:2 0 10:0 0 11:4 0 13:2 0 15:0 0 16:4 0 18:2 0 20:0 0 21:4 0 23:2 0 1:0 0 day time (hh:mm) 26 28 30 32 34 36 38 40 42 44 ai r t em pe ra tu re d eg re e (c ) 12 16 20 24 28 32 36 40 44 48 r el at iv e h um id ity (% ) 11-6-2015 evaporative cooling effectivness ec by splash water 0 100 200 300 400 500 600 700 800 900 h or iz on ta l s ol ar in te ns ity ( w /m ^2 ) 0.28 0.32 0.36 0.40 0.44 0.48 0.52 e va po ra tiv e c oo lin g ef ec tiv ne ss % indoor temp. outdoor temp indoor rh% outdoor rh% ec effectivness 40 50 60 70 80 90 100 110 120 130 140 150 160 length's part from test room to measure temperature (cm) 40 50 60 70 80 90 100 110 h e ig h t' s p a rt f ro m t e s t r o o m , t o m e a s u re t e m p e ra tu re ( c m ) 28.3 28.4 28.5 28.6 28.7 28.8 28.9 29.0 29.1 29.2 29.3 29.4 north side 11/6/2015 -10:00 pm dataec-v-l2 fig. 15-a. effect of evaporative cooling on the temperature distribution in mid layer test room (08:00 am). fig. 15-b. effect of evaporative cooling on the temperature distribution in mid layer test room (10:00 am). 0:00 1:40 3:20 5:00 6:40 8:20 10:00 11:40 13:20 15:00 16:40 18:20 20:00 21:40 23:20 day time (hh:mm) 30 32 34 36 38 40 42 44 46 48 ai r t em pe ra tu re d eg re e (c ) 0 2 4 6 8 10 12 14 16 18 20 re la tiv e hu m id ity % 0 100 200 300 400 500 600 700 800 900 ho riz on ta l s ol ar in te ns ity ( w/ m ^2 ) 4-6-2015data ventilation only -6 -4 -2 0 2 4 6 (t ou t-t in ) d eg re e (c ) indoor temp. outdoor temp. indoor rh% outdoor rh% h solar intensity tout-tin 40 50 60 70 80 90 100 110 120 130 140 150 160 length's part from test room to measure temperature (cm) 40 50 60 70 80 90 100 110 h e ig h t' s p a rt f ro m t e s t r o o m , t o m e a s u re t e m p e ra tu re ( c m ) 30.8 30.9 31.0 31.1 31.2 31.3 31.4 31.5 31.6 31.7 31.8 31.9 32.0 32.1 32.2 north side 11/6/2015 -08:00 am dataec-v-l2 fig.13 average temperature for indoor and outdoor through test day for vent only. fig.14. evaporative cooling effectiveness through test day. oc oc talib k. murtadha al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 8098 (2016) 94 fig. 15-c. effect of evaporative cooling on the temperature distribution in mid layer test room (12:00 pm ). fig. 15-d. effect of evaporative cooling on the temperature distribution in 3d test room (02:00 pm). fig. 15-e. effect of evaporative cooling on the temperature distribution in mid layer test room (04:00 pm). fig. 15-f. effect of evaporative cooling on the temperature distribution in mid layer test room (06:00 pm) fig. 15-g. effect of evaporative cooling on the temperature distribution in mid layer test room (08:00 pm). 40 50 60 70 80 90 100 110 120 130 140 150 160 length part from test room to measure temperature (cm) 40 50 60 70 80 90 100 110 h ig h p a rt f ro m t e s t r o o m t o m e a s u re t e m p e ra tu re ( c m ) 30.2 30.4 30.6 30.8 31.0 31.2 31.4 31.6 31.8 32.0 32.2 32.4 32.6 north side 11/6/2015 -12:01 pm dataec-v-l2 40 50 60 70 80 90 100 110 120 130 140 150 160 length's part from test room to measure temperature (cm) 40 50 60 70 80 90 100 110 h e ig h t' s p a rt f ro m t e s t r o o m , t o m e a s u re t e m p e ra tu re ( c m ) 33.2 33.3 33.4 33.5 33.6 33.7 33.8 33.9 34.0 34.1 34.2 34.3 34.4 34.5 34.6 34.7 north side 11/6/2015 -02:00 pm dataec-v-l1 40 50 60 70 80 90 100 110 120 130 140 150 160 length's part from test room to measure temperature (cm) 40 50 60 70 80 90 100 110 h e ig h t' s p a rt f ro m t e s t r o o m , t o m e a s u re t e m p e ra tu re ( c m ) 33.0 33.2 33.4 33.6 33.8 34.0 34.2 34.4 34.6 34.8 35.0 35.2 35.4 35.6 north side 11/6/2015 -02:00 pm dataec-v-l2 40 50 60 70 80 90 100 110 120 130 140 150 160 length's part from test room to measure temperature (cm) 40 50 60 70 80 90 100 110 h e ig h t' s p a rt f ro m t e s t r o o m , t o m e a s u re t e m p e ra tu re ( c m ) 33.4 33.6 33.8 34.0 34.2 34.4 34.6 34.8 35.0 35.2 35.4 35.6 35.8 north side 11/6/2015 -02:00 pm dataec-v-l3 40 50 60 70 80 90 100 110 120 130 140 150 160 length's part from test room to measure temperature (cm) 40 50 60 70 80 90 100 110 h e ig h t' s p a rt f ro m t e s t r o o m , t o m e a s u re t e m p e ra tu re ( c m ) 34.4 34.6 34.8 35.0 35.2 35.4 35.6 35.8 36.0 36.2 36.4 36.6 11/6/2015 -04:00 pm dataec-v-l2 north side 40 50 60 70 80 90 100 110 120 130 140 150 160 length part from test room to measure temperature (cm) 40 50 60 70 80 90 100 110 h ig h p a rt f ro m t e s t r o o m t o m e a s u re t e m p e ra tu re ( c m ) 33.6 33.7 33.8 33.9 34.0 34.1 34.2 34.3 34.4 34.5 34.6 34.7 34.8 34.9 35.0 35.1 35.2 11/6/2015 -06:00 pm data-ec-v-l2 40 50 60 70 80 90 100 110 120 130 140 150 160 length's part from test room to measure temperature (cm) 40 50 60 70 80 90 100 110 h e ig h t' s p a rt f ro m t e s t r o o m , t o m e a s u re t e m p e ra tu re ( c m ) 30.3 30.4 30.5 30.6 30.7 30.8 30.9 31.0 31.1 31.2 31.3 31.4 31.5 31.6 31.7 31.8 31.9 32.0 11/6/2015 -08:00 pm dataec-v-l2 north side oc oc oc oc oc oc talib k. murtadha al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 8098 (2016) 95 8.00 10.00 12.00 14.00 16.00 18.00 20.00 22.00 24.00 day time (hh:mm) 6 8 10 12 14 16 18 20 22 24 m as s fl o w r at e o f ai r in c h im n ey g ap ( kg /h r) mass flow rate in chimney gap mid way up chimney gap mid way down chimney gap before outlet up chimney gap before outlet down chimney gam fig. 15-h. effect of evaporative cooling on the temperature distribution in mid layer test room (10:00 pm). fig. 15-i. effect of evaporative cooling on the temperature distribution in mid layer test room (12:00 am). fig. 16. air change per hour in evaporative cooling mode. so, the mass flow rate through the test room is equals to the mass flow rate through the chimney with respect to the synchronous change in value for volume flow rate and density. maximum of mass flow rate of air through test room approximately 1.6.61 kg.hr -1 in value. air gap temperature in vertical fixed chimney shown in fig.18, the air temperature are measured in three positions in chimney gap, after inlet, in the mid way, and before outlet of chimney gap. results refer to increase in air temperature along the way of chimney length, and the heights of air temperature in same level are near the tesb. fig.19. shows the heat storage efficiency (hse) with maximum value in 10:00 am, because the higher difference in temperature between inside tesb, and it’s up-surface collector (0.75*1.5) m 2 accrues at that time. hse equals the summation of change of energy storage through time to the summation of solar energy through same time. 4. conclusions from the experimental results, the following conclusions can be drawn: employing the evaporative cooling effect, made more successfully comfortable zone ,and more suitable for human live mode, and that done by decreasing the room air temperature with respect to the increasing of relative humidity. fig. 17. experimental value of mass flow rate. comfort condition does not cover the day time only but also the night time by using the thermal energy storage material. accomplished double pass solar chimney collector ensures a good aspect ratio between 40 50 60 70 80 90 100 110 120 130 140 150 160 length's part from test room to measure temperature (cm) 40 50 60 70 80 90 100 110 h e ig h t' s p a rt f ro m t e s t r o o m , t o m e a s u re t e m p e ra tu re ( c m ) 28.3 28.4 28.5 28.6 28.7 28.8 28.9 29.0 29.1 29.2 29.3 29.4 north side 11/6/2015 -10:00 pm dataec-v-l2 40 50 60 70 80 90 100 110 120 130 140 150 160 length's part from test room to measure temperature (cm) 40 50 60 70 80 90 100 110 h e ig h t' s p a rt f ro m t e s t r o o m , t o m e a s u re t e m p e ra tu re ( c m ) 27.0 27.1 27.2 27.3 27.4 27.5 27.6 27.7 27.8 27.9 28.0 28.1 28.2 north side 12/6/2015 -00:01 am dataec-v-l2 8.00 10.00 12.00 14.00 16.00 18.00 20.00 22.00 24.00 day time (hh:mm) 3.6 4.0 4.4 4.8 5.2 5.6 6.0 6.4 6.8 7.2 7.6 a c h experimental value ach depend on mid way of tilt chimney gap experimental value ach depend on end way of tilt chimney gap theoretical calculation oc oc talib k. murtadha al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 8098 (2016) 96 chimney length and the gap thickness, the ratio is bigger than 12, make a chance to prevent reverse air flow in chimney gap. fig.18. vertical sc air gap temperature. fig. 19. solar radiation, energy summation and heat storage efficiency. nomenclature a area ach air chinge per hour cd discharge coefficient cp specific heat ec evaporative cooling ece evaporative cooling efficiency etc evacuated tubular collector g gravitational acceleration h enthalpy , height hse eat storage efficiency i-beam beam solar radiation lc characteristic length m mass m o mass flow rate p pressure pw paraffin wax q heat sc solar chimney t , t temperature, time tesb,m thermal energy storage-box, material u velocity v o volumetric flow rate w moisture contain greek letters inclination density width of melting zone sun altitude angle latitude angle hour angle declination angle solar radiation angle, 8.00 10.00 12.00 14.00 16.00 18.00 20.00 22.00 24.00 day time (hh:mm) 26 27 28 29 30 31 32 33 34 35 a ir t e m p e ra tu re i n in le t v e rt ic a l c h im n e y -g a p ( c ) distance from tesb 0.25 cm 1.75 cm 3.25 cm 4.75 cm 6.25 cm 8.00 10.00 12.00 14.00 16.00 18.00 20.00 22.00 24.00 day time (hh:mm) 28 29 30 31 32 33 34 35 36 37 38 39 40 41 a ir t e m p e ra tu re i n m id h e ig h t v e rt ic a l c h im n e y -g a p ( c ) distance from tesb 0.25 cm 1.75 cm 3.25 cm 4.75 cm 6.25 8.00 10.00 12.00 14.00 16.00 18.00 20.00 22.00 24.00 day time (hh:mm) 28 29 30 31 32 33 34 35 36 37 38 39 40 41 a ir t e m p e ra tu re i n o u tl e t v e rt ic a l c h im n e y g a p ( c ) distance from tesb 0.25 cm 1.75 cm 3.25 cm 4.75 cm 6.25 cm 8.00 10.00 12.00 14.00 16.00 18.00 20.00 day time (hh:mm) 0 100 200 300 400 500 600 700 800 900 1000 s o la r r a d ia ti o n r a te b e h in d a c r y li c , 4 5 d e g r e e a n g le 2000 4000 6000 8000 10000 12000 14000 16000 18000 20000 e n e r g y s u m m a ti o n t h r o u g h d u r a ti o n c h a rg e t im e (k j ) 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 h e a t s to r a g e e ff ic ie n c y % 11/6/2015 solar radiation energy summation heat storage effeciency talib k. murtadha al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 8098 (2016) 97 solar chimney tilt angle heat storage effeciency subscripts a air c copper g gas i inlet l liquid m melting o outlet s solid sl latent heat of fusion 5. references [1] m. maerefat, a.p. haghighi , “ passive cooling of building by using integrated earth to air heat exchanger and solar chimney”, renewable energy 35, pp. 2316-2324, 2010. [2] m. maerefat, a.p. haghighi ,“ natural cooling of stand-alone houses using solar chimney and evaporative cooling avity”, renewable energy 35, pp. 2040-2052, 2010. [3] usama mustafa , “using solar chimney to suck air through a wet ped”, journal of engineering and development, vol. 15, no.2, pp. 205-213,june-2011. [4] amin h. poshtiri, neda g., “ comparative survey on using two passive cooling systems, solar chimneyearth to air heat exchanger and solar chimney-evaporative cooling cavity”, world renewable congress, pp. 2102-2109, 2011, sweden. [5] amr s., hiroshi y., tomonobu g., “integration of evaporative cooling technique with solar chimney to improve indoor thermal environment in the new assiut city, egypt”, international journal of energy and environment engineering, pp. 115, 2013. [6] md. m. rahman, muhammad m.,” a passive cooling system of residential and commercial buildings in summer or hot season”, recent advances in renewable energy source, pp.100-105. [7] md. f. rabbi, mrittunjoy sarker, “alternative room cooling system”, american journal of engineering research (ajer), vol. 4, issue-6, pp. 215-218, 2015. [8] arkan u.meko, ”energy storage by phase change by using paraffin wax”, msc, thesis, machines and equipment, university of technology, baghdad, iraq, 2004. (arabic) [9] helmut e. feustel , corina stetiu,”thermal performance of phase change wallboard for residential cooling application”, environmental energy technologies division, ernest orlando lawrence berkeley nationalla boratory, university of california berkeley, ca 94720, usa,1997. [10] s. salam, et al., “psychometric analysis for arbitrary dry-gas mixtures and pressres using microcomputer”, ashrae transaction, part-1,vol. 92, 1986. [11] hussain h. al-kayiem, ahmed k. hussein, toh seng peow, “investigations of natural convective heat transfer in rectangular thermal passages“, international journal of mechanical, aerospace, industrial and mechatronics engineering vol.7, no. 3, pp 159-164,2013. [12] salah larbia, adel el hella,“thermo-fluid aspect analysis of passive cooling system case using solar chimney in the south regions of algeria”, energy procedia 36 pp. 628 – 637, 2013. [13] j. mathur, et al. “ summer-performance of inclined roof solar chimney for natural ventilation”, energy and building 38, pp. 1156-1163, 2006. [14] b. belfuguais, s. larbi,“passive ventilation system analysis using solar chimney in south of algeria” world academy of science, engineering and technology vol. 58, pp. 26-30, 2011. [15] c. seytier,et al., “combined convectiveradiative thermal analysis of an inclined rooftop solar chimney” journal of solar energy engineering, vol. 135 feb. , 2013. (2016) 8098، صفحة 3، العذد12ذجلة الخىارزمً الهنذسٍة المجلمطالب كشاش مرتضى مع مادة ثنائٍة الطىر رٌذ ألخيخٍرسخخذا المذننة الشميٍة اليليٍة يً الخيالدراسة عملٍة ومصفىية رغىة النحاش كخسان حراري طالب كشاش مرتضى * صالححيٍه مجٍذ ** علً داود سلمان*** انجبيؼخ انزكُىنىجُخ / *لسى انهُذسخ انًُكبَُكُخ انجبيؼخ انزكُىنىجُخ خ /*لسى انهُذسخ انكهشويُكبَُكُ*،** * talib_km@yahoo.comانجشَذ االنكزشوٍَ: * hussein_maj@yahoo.comانجشَذ* االنكزشوٍَ: aligaphory@yahoo.comانجشَذ*** االنكزشوٍَ: الخالصة فٍ يذَُخ ثغذاد نكم يٍ انطىل وانؼشض واسرفبع انغشفخ انًجُُخ فٍ ( يزش 1.5*1.5*2خالل هزِ انذساسخ انؼًهُخ، رى ثُبء غشفخ اخزجبس يؼضونخ ثذجى ) أَىاع يٍ ثؼذح جهضد غشفخ االخزجبس 126ثًُُب صًى كال انًذاخٍ انشًسُخ ظًٍ َسجخ غىل انً ػشض انفجىح انهىائُخ ثًمذاس اكجش يٍ انمًُخ انذشجخ 6 نهعىء وػبصلفهُبنك انًذخُخ انؼًىدَخ انضبثزخ راد انخضاٌ انذشاسٌ انًسطخ وانًذهىٌ ثذهبٌ اسىد غُش نًبع ويغهفخ ثسطخ َفبر انًجًؼبد انشًسُخ، ورذسٍُ رىنُذ لىح انطفى، فٍ هزِ وانًىصىنخ ثبنزىانٍ يغ انًذخُخ انضبثزخ نضَبدح اسرفبع انًذخُخ انكهٍ دسجخ 45وهُبنك انًذخُخ انًبئهخ ثضاوَخ دشاسَب، االصيخ ػٍ انًذخُخ صالصخ خضاَبد دشاسَخ ػهً غىل انًذخُخ يغ وجىد فجىرٍ هىاء ػهً غشفٍ انًجًغ نجشَبٌ انهىاء خالنهًب يٍ خالل رىنُذ لىح انطفى خ يٍ االَبثُت انضجبجُخ انًضدوجخ وانًفشغخ يٍ غشَك صَبدح اَزمبل انذشاسح انً انهىاء يغ ربيٍُ يُغ دذوس جشَبٌ هىاء خهف6ٍ كًب رى صساػخ يجًىػ 45انهىاء وانزٍ فٍ داخم كم وادذِ يُهب اَجىة دشاسٌ وثذوٌ دشىح )صشيىسبَفىٌ( دُش رىصم هزِ االَبثُت انًًُهخ ثضاوَخ o انً انُصف انسفهٍ يٍ رذزىٌ ػهً يؼذَُخ يغهىَخ خضاَبد فٍ انًذخُخ انشًسُخ ثبسزخذاو خضٌ دشاسح اإلشؼبع انشًسٍ رى انخضاٌ انذشاسٌ نهًذخُخ انشًسُخ انؼًىدَخ انضبثزخ6 خ نزىنُذ لىح يىاد يزغُشح انطىس نهب لبثهُخ ػهً خضٌ انذشاسح ويذػًخ ثشغىح يؼذَُخ نزذسٍُ انًىصهُخ انذشاسَخ نًبدح انخض6ٌ رسزخذو انذشاسح انًخضوَ داخم انغشفخ، نهسًبح نههىاء انخبسجٍ انُمٍ ثبنذخىل ػجش فزذبد رذزىٌ ػهً دشىِ انطفى ويٍ صى دش انهىاء خالل انًذخُخ انشًسُخ وػًم رخهم ظغػ انزجشَذ أنزجخُش6ٌ أظهشد انُزبئج انؼًهُخ وانزٍ رى وثًشوس انهىاء فىق سطخ انذشىح انًجزهخ يًب َؤدٌ إنً دذوس سهُهىصَخ نهب انمبثهُخ ػهً ايزصبص انًبء، سبػخ يزىاصهخ، دُش إٌ الم فشق دسجخ 24إجشائهب فٍ ثذاَخ ويُزصف انشهش انسبدط، إنً إيكبَُخ خفط دسجخ دشاسح دُض االخزجبس ظًٍ فزشح اخزجبس يسبءا وكزنك ثفشق يًبصم َذذس ػُذ انسبػخ 20:00انسبػخ دسجخ يئىَخ ػُذ 3.5دشاسح ثٍُ دُض االخزجبس وظشف انهىاء انخبسجٍ كبَذ يب َمبسة كًب أظهشد انُزبئج .يٍ ػًش فزشح االخزجبس 15:00 -11:00دسجخ يئىَخ وَذذس خالل 8.5-9.2 صجبدب، ايب اػهً فشق فٍ دسجخ انذشاسح ثًمذاس 03:00 -30.5فؼبنُخ انزجشَذ انزجخُشٌ يذيثهغذ ، فبض فٍ فؼبنُخ انزجشَذ انزجخُشٌفؼبنُخ اسزخذاو انخضٌ انذشاسٌ انشًسٍ، نفزشح يب ثؼذ انًغُت يغ يالدظخ اَخ اكجش يؼذل و، 0.371ظًٍ يؼبيم رذفك خالل انًُظىيخ ( خالل انسبػخ6.187-3.8) ذلؼ، ايب رهىَخ انذُض فكبٌ ثًظًٍ جشَبٌ انهىاء انطجُؼٍ 37.5 kg.hr 36.651).رذفك كزهٍ نههىاء فكبٌ ثًمذاس -1 ) mailto:talib_km@yahoo.comالبريد mailto:hussein_maj@yahoo.com*البريد mailto:aligaphory@yahoo.com***البريد <4d6963726f736f667420576f7264202d20c7cde3cf20e6d3c7e3ed20e6d5ddc7c133302d3339> al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 14, no.2, june, (2018) p.p. 3039 optimization of diffusion bonding of pure copper (ofhc) with stainless steel 304l ahmed ali akbar akbar * sami abualnoun ajeel** safaa mohammed hassoni*** *,**department of production engineering and metallurgy/ university of technology ***institute of technology baghdad/ middle technical university ***email: as_5599@yahoo.com (received 10 april 2017; accepted 28 november 2017) https://doi.org/10.22153/kej.2018.11.002 abstract this work deals with determination of optimum conditions of direct diffusion bonding welding of austenitic stainlesssteel type aisi 304l with oxygen free high conductivity (ofhc) pure copper grade (c10200) in vacuum atmosphere of (1.5 *10-5 mbr.). mini tab (response surface) was applied for optimizing the influence of diffusion bonding parameters (temperature, time and applied load) on the bonding joints characteristics and the empirical relationship was evaluated which represents the effect of each parameter of the process. the yield strength of diffusion bonded joint was equal to 153 mpa and the efficiency of joint was equal to 66.5% as compared with hard drawn copper. the diffusion zone reveals high microhardness than copper side due to solid solution phase formation of (cuni). the failure of bonded joints always occurred on the copper side and fracture surface morphologies are characterized by ductile failure mode with dimple structure. optimum bonding conditions were observed at temperature of 650 ◦c, duration time of 45 min. and the applied stress of 30 mpa. the maximum depth of diffuse copper in stainless steel side was equal 11.80 µm. keywords: diffusion bonding, pure copper, stainless steel, 304 l. 1. introduction joining dissimilar metals demands for increasing importance in many applications to utilize hybrid structures and compounds properties like high strength, thermal conductivity and good corrosion resistance [1]. the applications of dissimilar metals such as austenitic stainless steelcoppers (ofhc) are widely used in traditional and nuclear power plants [2]. however, the welding of austenitic stainless steel with copper alloys by conventional welding processes is not recommended by these methods because of probability of formations of newly intermetallic compounds at the weld pool. copper and its alloys are majorly utilized for pipelines of heat exchangers; valve and clad plate for steel hulls of small ships, etc. alloys of copper have enough resistance corroded in seawater [3]. broadly, the application of austenitic stainless steel to copper joints is utilized in the heat exchanger which consists of plates of austenitic stainless steel to copper [4]. in vessel apparatuses of the international thermonuclear experimental reactor austenitic stainless steel and copper alloy are considered as a chief structure of materials for the first wall and find out systems. the austenitic stainless steel is also utilized in the nuclear surroundings [5]. innovative joining operation of similar and dissimilar materials is provided by diffusion bonding welding process without producing macroscopic distortion; with minimum dimensional tolerance and no phase transformation or microstructional change occurred during the welding process [6]. a ahmed ali akbar akbar al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 3039 (2018) 31 diffusion bonding process also permits the production of highquality joints with little or no need for post weld machining [7]. design of experimental (doe) was used in this work to get a suitable number of samples to be tested to characterize the effect of bonding variables (temperature, duration time and applied load) on the diffusion bonding joints. bilgin (2009) studied the interfacial properties of diffusion bonding of stainless steel type 304l with ti-6al-4v using cu interlayer. this work was applied at temperature range of (820-870) c◦, time range of (50-90) min. and load of 1mpa. the joints were examined using sem, eds, shear test and micro hardness test. at different conditions to predict optimum conditions of shear strength at 870 c◦, and duration time of 90 min. due to better coalescence [8]. xiong (2012) studied the diffusion bonding of stainless steel to copper with tin, bronze and gold interlayer. the diffusion bonding of two materials was obtained under temperature range of (830-955) c◦, load 3mpa and duration time of 60 min. the optimum conditions observed for this work were at 850 c◦ to get tensile strength of 228 mpa for tb-au interlayer. the microstructure of joint was examined using sem and eds [9]. sabetghadam (2010) evaluated the microstructure of diffusion bonded joint between stainless steel 410 and copper using ni as interlayer. the bond joints were applied at temperature range of (800950) c◦, load of 12 mpa and duration time was 60 minutes in vacuum of (1.3 x 10-2 pa). the microstructure and phases near bonding interface were examined using optical microscope, sem and eds. the result indicated an increase in thickness of reaction layer with an increase in temperature [10]. kaya (2011) worked on the diffusion bonding of stainless steel with copper by two methods convential diffusion bonding and non-conventional diffusion bonding by applied external current. the specimens to be bonded were in dimensions of 10mm. dia. and 35mm. length. the bonding conditions were 875 c◦, duration time 30 min. and applied load 3mpa, with heating and cooling rate of 20 c◦/min. the interface of bonded joints was examined by tensile test and sem&eds. the strength of conventional bonding was 159 mpa and for nonconventional 169 mpa. the total diffusion of convential was 6.4% wt. while for non-convential was 9.1% wt [11]. all previous studies were restricted to the evaluation of the diffusion parameters influence and microstructure on the interface of the diffusion area. but, there are no studies of the characterization of the influence of the diffusion bonding metallurgical transformation on the corrosion behavior of (aisi 304l/pure copper) bonding joints. the present work makes an effort with a contribution to this challenging dilemma. 2. experimental 2.1 preparation of vacuum diffusion bonding unit in order to evaluate the sound diffusion bonding of two dissimilar materials of pure copper (ofhc) grade (c10200) and austanitic stainless steel type aisi 304l, the diffusion bonding requires to be applied in vacuum. joining under vacuum reveals minimum impurity content, even in the case of high reactive metals. vacuum provides faster and more complete degassing of joined materials and removal of oxides, impurities and contaminants from both surface and bulk materials. the system consists of vacuum diffusion pump, double stage rotary vacuum pump, electrical loading system with capacity of 50 ton, vacuum tube furnance with heating system, vacuum fitting and cooling system for furnace and diffusion as shown in fig. (1). fig .1. vacuum diffusion bonding unit. 2.2 materials materials used in this work were wrought austenitic stainless steel aisi 304l according to (astm volume 01.01) and hard drawn pure copper (ofhc) grade (c10200) according to (astm volume 02.01). ahmed ali akbar akbar al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 3039 (2018) 32 table 1, mechanical properties of two materials used. materials yield strength(mpa) ultimate strength (mpa) elongation % hardness stainless 304l 210 564 58 hrb=85 copper(ofhc) 230 255 28 hb=65 2.3 specimens preperation for diffusion bonding process the materials to be joined by diffusion bonding were pure copper(ofhc) and stainless steel 304l. cylindrical samples of 15mm diameter for each lengths were used with 30 mm and 60 mm for copper and stainless steel respectively[12]. the mating sample surface was prepared using convential grinding on 1200 grade sic papers followed by polishing with diamond paste using fabricated holder to get flat surface . the specimens were cleaned in ultrasonic bath using acetone for 15 min. to remove adhered contaminations and dried in air before bonding. 2.4 doe (design of expermental) 2.4.1 selection of process parameter (surface response) the working range for each parameter is given in table (2). this represents boundary of optimum conditions to be searched according to (0.5-0.8 melting temperature) [6]; (4-13% бy) applied load and duration time range (15-75) min. from previous works. these ranges are selected according to the recommended optimum ranges of temperature, the duration time and applied load of diffusion bonding welding process [14]. table 2, working ranges of selected parameters. 2.4.2 construction of the experimental design matrix the value of coded variables and uncoded variables for experimental design is shown in table (3). table 3, experimental design matrix. exp. numbers coded value original value bonding temp.(◦c)t1 bonding time(min.)t2 bonding pressure(mpa)t3 bonding temp.(c◦) bonding time(min.) bonding pressure(mpa) 1 -1 -1 -1 600 30 15 2 +1 -1 -1 700 30 15 3 -1 +1 -1 600 30 25 4 +1 +1 -1 700 30 25 5 -1 -1 +1 600 60 15 6 +1 -1 +1 700 60 15 7 -1 +1 +1 600 60 25 8 +1 +1 +1 700 60 25 9 -1.682 0 0 550 45 20 10 +1.682 0 0 750 45 20 11 0 -1.682 0 650 45 10 12 0 +1.682 0 650 45 30 13 0 0 -1.682 650 15 20 14 0 0 +1.682 650 75 20 15 0 0 0 650 45 20 16 0 0 0 650 45 20 17 0 0 0 650 45 20 18 0 0 0 650 45 20 19 0 0 0 650 45 20 20 0 0 0 650 45 20 max. min. parameters 750 550 temperature (◦c) 75 15 duration time (min) 30 10 applied pressure (mpa) ahmed ali akbar akbar al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 3039 (2018) 33 where: t1: the code value of temperature; t2: the code value of duration time; t3: the code value of applied load. 3.7.1 tensile test of diffusion bonded joints to evaluate the tensile strength of bonded joints after welding, the bonded joint specimens were sectioned into small specimens for microstructure, mechanical properties tensile test. the tensile strength value was obtained by average value for tests. the tensile test specimens were cut by using wire cutting machine from bonded joints according to (astm e8-89) , in such a way that the weld zone was positioned at the center of gauge length. the tensile test specimen shown in fig. (2), was applied by using universal testing machine type wdw 200 e with cross speed 0.1 mm/min. dimensions (mm) of tensile test specimen with thickness of (6mm) according to astm e8-89 tensile test specimen fig. 2. specimens for tensile test. 4. results and discussions 4.1 tensile test of diffusion bonding joints the bond strength of the bonding joints represents the response for the program min tab16. as shown in fig.3 (a). the results from tensile tests are shown in table (3). the fracture of most tensile test specimens was occurred in the copper side not at the bond line as shown in fig.3 (b). this means the bond area is much stronger than copper side; this due to the used of vacuum atmosphere conditions which lead to better coalescence. this results in complete mating of two surfaces, and diffusion of copper atoms leads to good bonding. fig. (a) fig. (b) fig. 3. (a) a set of diffusion bonding joints at different bonding conditions. ( b) fracture of diffusion bonding joints. ahmed ali akbar akbar al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 3039 (2018) 34 table 3, results of tensile tests of bonding joints. 4-2 parametric analysis of bond strength the main effect of plot of each variable of (t1, t2 and t3) on the bond strength is shown in figure (4). the bond strength increases with an increase in temperature (t1) until reaching maximum value at temperature of 650 ◦c and then decreases until reached a temperature of 750 ◦c. this indicates maximum strength at 650 ◦c with higher bond strength than other temperatures values of bonding. the effect of a second variable that is, duration time of bonding (t2) on the bond strength of 15min. gets on the acceptable bond strength, but when time increases fluctuation in bond strength can be seen until reaches the maximum value of 75min. finally, the effect of third variable (t3) is applied load on the bond strength at low values of load. this indicates low bond strength, but the maximum value of bond strength was observed at applied stress of (30 mpa) due to complete mating surface between two bonding metals used. fig. 5. main effects on fracture stress. 4.2.1 response surface regression the analysis of results of bond strength versus t1 (temperature), t2 (duration time) and t3 (applied stress) was done using uncoded units of input data. regression was estimated coefficients for bond strength in order to obtain the significance by calculating (p-level) for each coefficient to determine which of these significant factors have effect on the bond strength. depending on the significance level (α=0.05), the coefficient with plevel value is greater than 0.05 which is not significant like (t3, t22, t33, t13 and t23), coefficients which have p-level less than 0.05 like (to, t1, t2, t11and t12) represent the effective values on the bond strength of t1 temp. (◦c) t2 time (min.) t3 stress (mpa) fracture stress (mpa) fracture location ultimate strength(mpa) elongation% 600 30 15 128.0 at copper 178 26 700 30 15 30.0 at interface 113 8 600 30 25 123.0 at copper 210 44.5 700 30 25 45.0 at interface 76 5.5 600 60 15 38.0 at interface 49 3.5 700 60 15 58.0 at copper 142 11.5 600 60 25 80.0 at copper 193 22.5 700 60 25 113.0 at copper 191 24 550 45 20 53.0 at copper 120 12.5 750 45 20 4.8 at interface 56 4.5 650 45 10 57.0 at copper 138 16 650 45 30 153.0 at copper 210 40.5 650 15 20 128.0 at copper 200 27 650 75 20 127.0 at copper 200 40.5 650 45 20 110.0 at copper 200 38.5 650 45 20 49 at interface 82 3.5 650 45 20 105.0 at copper 210 42.5 650 45 20 112.0 at copper 184 44.5 650 45 20 107.0 at copper 173 24 650 45 20 112.5 at copper 225 44.5 ahmed ali akbar akbar al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 3039 (2018) 35 diffusion bonding joints of two materials, therefore the mathematical model of significant parameters may be written as shown in equation (1). y = -1711.34 + 8.19t1 29.85t2 0.01 t1 2+ 0.04t1*t2 …(1) 4.2.2. anova results of bond strength the analysis of variance (anova) for the bond strength is shown in table (4); it is made by using fisher test (f-test) and results. it can be observed from this table that, the coefficient of r.sq=92.80% but the r.sq (adj.) =86.32%. the difference between two values of r is small therefore, this means the three variables (t1, t2 and t3) qualified in variation of bond strength by (86.32%) and about of (13.68 %) due to random error and noise or the effects of other variables. depending on significance value of (0.05), observed from the table, the total of p value is less than 0.05 therefore the test is significant. table 4, avona for bond strength with significant level (0.05). source df seq. (ss) adj. ss adj.(ms) f p regression 9 28882.0 28882.0 3209.1 14.32 0.000 linear 3 8649.8 18994.4 6331.5 28.26 0.000 square 3 12451.0 12451.0 4150.3 18.52 0.000 interaction 3 7781.2 7781.2 2593.7 11.58 0.001 residual error 10 2240.6 2240.6 224.1 ---------- lack of fit 5 1588.2 1588.2 317.6 2.43 0.176 pure error 5 652.4 652.4 130.5 ----------- total 19 31122.7 ------------------------- r-sq. =92.80% r-sq.(pred)=55.86% r-sq. (adj)=86.32% 4.2.3 optimization of surface response (bond strength) the optimum value of bonding conditions is calculated using the equation (2), to predict the maximum value of bond strength of diffusion bonding joints for various bonding conditions. �� = ��� � � �� � � � …(2) where: di = individual desirability. yi = response. ti= target. li= lower limit values of the response. r= unit weight factor (usually = 1). the calculated optimum results are shown in table (4); optimum bonding conditions was observed at experiment number 12, with bonding conditions of 650 ◦c, 45 min. and 30 mpa applied stress. the high value of di equal to (1) represents the maximum value of bond strength and the value of di=0 represents the minimum value of bond strength [14]. the maximum tensile strength of bonding joint was obtained at the bonding conditions of temperature at 650 ◦c, duration time of bonding at 45 min. and applied load of complete coalescence at 30 mpa. joint efficiency is attributed to the quality of the joints. therefore, joint efficiency was estimated. [15] as follow: joint efficiency = 153 mpa/ 230 mpa (for copper) % = 66.5% joint efficiency= 153 mpa/550 mpa (for stainless steel) %= 28% 4.3 surface and counter plots the response surface analysis which has two types of plots, the first is three dimensions (3d) representing the surface plot. the second is the two dimensions (2d) indicating the contour plot. the two plots were studied the combination effects of bonding parameters (t1, t2 and t3) on the bond strength of joints. ahmed ali akbar akbar al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 3039 (2018) 36 table ranks of response surface of results. 4.3.1 effect of temperature and duration time on bond strength figures (5 a and b) indicate 3d surface and 2d contour plots which show combination effect of t1 (temperature) and t2 (duration time) at constant level (middle value) of t3 (applied stress) equal to (20 mpa.) on the bond strength. figure. (5 a) shows the effect of temperature and duration time on the surface response bond strength. it can be observed from this, the bond strength increases with an increase in temperature and duration time but the effect of temperature is more effective than duration time. the optimal bonding conditions are temperature of 650 ◦c and duration time at 45 min. the increase in temperature above 650 ◦c leads to rapid grain growth which leads to low bond strength [16]. fig. (5 b) represents the 2d contour plot for temperature with duration time. it indicates that the maximum bond strength observed at minimum temperature and duration time but it cannot be result in sound diffusion bonding joints. the optimum bonding condition at the range of 120180 mpa as shown in fig. (5 b). the combinations effect of temperature and duration time in contour was observed at maximum temperature of 650 ◦c and maximum duration time of 45 min., due to complete coalescence between two coupling surface and high diffusion rate. (a) (b) fig. 5. effect of temperature and time on bond strength (a) 3d surface plot (b) 2d contour. no. t1 (◦c) t2 (min.) t3 (mpa.) fracture stress. (mpa.) di rank 1 600 30 15 128.0 0.8313 2 2 700 30 15 30.0 0.1700 18 3 600 30 25 123.0 0.7975 4 4 700 30 25 45.0 0.2712 16 5 600 60 15 38.0 0.2240 17 6 700 60 15 58.0 0.3589 13 7 600 60 25 80.0 0.5074 12 8 700 60 25 113.0 0.7300 5 9 550 45 20 53.0 0.3252 15 10 750 45 20 4.8 0.000 20 11 650 45 10 57.0 0.3522 14 12 650 45 30 153.0 1 1 13 650 15 20 128.0 0.8313 2 14 650 75 20 127.0 0.8245 3 15 650 45 20 110.0 0.7098 8 16 650 45 20 49 0.5209 11 17 650 45 20 105.0 0.6761 10 18 650 45 20 112.0 0.7233 7 19 650 45 20 107.0 0.6896 9 20 650 45 20 112.5 0.7267 6 ahmed ali akbar akbar al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 3039 (2018) 37 4.3.2 effect of temperature and applied stress on bond strength. figures (6 a and b) illustrate combination effects of temperature and applied stress on the bond strength. figure (6 a) shows gradual increase in bond strength until reached maximum value at load of 30 mpa. the bonding load was applied in order to secure a tight contact between the bonding surface and a vital condition for the interdiffusion atoms of metals jointed. if the applied stress is less than the optimum value, then the bond strength decreases. the optimum bonding temperature can be seen at 650 ◦c and at maximum applied load of 30 mpa. the effect of temperature on bond strength is more effective than the effect of applied load and the higher bond strength is 30 mpa. (a) (b) fig. 6. effects of temperature and applied stress on bond strength (a) 3d surface plot (b) 2d contour plot. 4.3.3 effect of time and applied stress on bond strength. the effect of the two variables of duration time (t2) and applied stress (t3) on the surface response bond strength is shown in figures (7) a and b. fig. (7 a), shows higher effect of duration time than applied load. the right region of plot shows high change in applied stress up to 30 mpa. these results are combined with the effect of duration time on the bond strength,when time increases until reached 45 min. with an increase in applied stress to reach 30 mpa. at this point maximum value of bond strength is observed. fig. (7 b) shows combination effects of high applied stress of 30 mpa and high duration time of 45 min. to get optimum value of maximum value of bond strength. mating surfaces are expanding almost instantaneously. when the applied load increases more than the increase in temperature this leads to plastic deformation and doesn’t get sound bonding joint between the two materials used [17]. (a) (b) fig. 7. effects of time and applied stress on bond strength (a) 3d surface plot (b) 2d contour plot. ahmed ali akbar akbar al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 3039 (2018) 38 5. conclusions 1. the dissimilar diffusion bonding joints show lower tensile strength than the base material of hard drawn pure copper (ofhc) side and the maximum bond strength is 153 mpa. 2. vacuum diffusion bonding unit has been successfully prepared and reached vacuum approximately of (1.5 * 10-5mbr). 3. the maximum tensile strength of diffusion bonding joint was observed for diffusion bonding joint at optimum bonding conditions of 650 ◦c, 45 min., and applied stress of 30 mpa, annealed at temperature of 800 ◦c, for 30 min. 4. the equation represent the effect of bonding conditions between hard drawn copper and austenitic stainless steel 304l with significant effects of bonding parameters was: y = -1711.34 + 8.19t1 29.85t2 0.01 t12 + 0.04t1*t2 5. the strong effects of diffusion bonding parameters are temperature˃ duration time˃ applied load. 6. the efficiency of optimum bonding joint was higher as compared with hard drawn copper and lower as compared with austenitic stainless steel. 6. references [1] j. c., lippod koteki d. j, “welding metallurgy and weldability of stainless steel”. new jersey: wiley (2005). [2] n. k. srinivasan, welding technology, fourth edition, romesh chander khanna, khanna (2012). [3] d. feron, “corrosion behavior and protection of copper and aluminum alloys in seawater”, wood head publishing limited and crc press llc, (2007). [4] k. bhanumurthy, d. joyson, a. laik, “diffusion bonding of nuclear materials”, brac nem letter, (2013), issuf no. 331. [5] r.k.roy, s.singh “joining of 304ss and pure copper by rapidly solidified cu-based braze alloy”, fusion engineering and design, (2011) 452-455. [6] kunda s., chatterjee s., mechanical properties of diffusion bonded joints between titanium and stainless steel with nickel interlayer, material science and engineering, (2007). [7] j. grum, slabe j. m,” the use of design and response surface methology for fast determination of optimal heat treatment conditions of different ni-co-mo surface roughness layers”, journal of material processing technology, (2014). [8] n. ozdemir, b. bilgin, interfacial properties of diffusion bonded ti-6al-4v to aisi 304 stainless steel bt inserting copper interlayer, journal of advanced manufacturing technology, (2009). [9] jiang-tao xiong, diffusion bonding of stainless steel to copper with tin bronze and gold interlayer, journal of material engineering and performance, (2012). [10] h. sabetghadam, a. zarei hanzaki, microstructure evaluation of 410 ss/cu diffusion bonded joint, journal of material science and technology, (2010). [11] yakop kaya, nizamettin kahraman, anovel approach of diffusion bonding of copper to stainless steel, journal of engineering manufacture, (2011). [12] ahmed ali akber akber, “diffusion bonding of oxygen high conductivity copper to austenitic stainless steel” phd thesis, university of technology, (1996). [13] rohit garg "effect of process parameters on performance measures of wire electrical discharg machining", ph.d. thesis, mechanical engineering department, national institute of technology, kurukshetra, (2010). [14] montgomery, d. c. and runger, g. c. applied statistics and probability for engineers, john wiley and sons. (2010). [15] s.assarzadeh and ghoreishi, statistical modeling and optimization of the edm parameters on wc-6% co composite through hybrid response surface methodologydesirability function approach, international journal of engineering science and technology, (2013). [16] m. balasubramanian, application of boxbehbken design of fabrication of titanium alloy and 304 stainless steel joints with silver interlayer, materials and design, (2015). [17] pilling j., solid state of superplastic a a 7475, materials science and technology, (1987). )2018( 14-21، صفحة 2د، العد14دجلة الخوارزمي الهندسية المجلماحمد علي اكبر اكبر 39 امثلية وصالت الربط االنتشاري للنحاس خالي األوكسجين عالي الموصلية مع الفوالذ المقاوم 304l للصدأ احمد علي اكبر اكبر* سامي ابو النون عجيل** صفاء محمد حسوني*** الجامعة التكنلوجية /قسم هندسة االنتاج والمعادن *,** ***الجامعة التقنية الوسطى / معهد التكنولوجيا بغداد _yahoo.com5599as@***البريد االلكتروني: ةالخالص يتضمن البحث تحديد الظروف المثالية للحام االنتشاري المباشر للنحاس خالي األوكسجين_ عالي الموصلية مع الصلب المقاوم للصدأ وقد تم استخدام برنامج )5-10*1 (mbrيصل الى ط المعدنين في جو مفرغ من الهواءمختبريا. وقد تم رب )l)304االوستنايتي نوع (minitab16) روف المثلى لربط المعدنين. ومن خالل استخدام البرنامج تم دراسة التاثير المشترك لعوامل الربط على قوة الربط. لمعرفة الظ لمعرفة التركيب (sem-eds)االلكتروني الماسح المجهريه لمنطقة الربط األنتشاري باستخدام المجهر البنيةوقد اجريت فحوصات لمعرفة األطوار التي تكونت في منطقة الربط ومن (xrd)والصالده المايكروية والتحليل الطيفي في منطقة الربط االنتشارالمجهري وعمق يعطي صفات جيده. تم ايجاد الظروف المثلى ااحادي اطوربوصفه (cuni)ن محلول جامد بين النحاس والنيكل خالل الفحوصات تبين تكوّ ميكاباسكال. ولمعرفة قوة الربط تم اجراء فحص الشد ٣٠دقيقه والجهد المسلط كان ٤٥وزمن ربط ٦٥٠◦c حرارةللربط هي عند درجة ان عمق ومقارنة بالنحاس %٦٦٫٥ميكاباسكال وذات كفاءة ربط ١٥٣لمنطقة الربط حيث كانت متانة الربط عند ظروف الربط المثلى تساوي . µm 11.80كان األنتشار الذي تم الحصول عليه في منطقة الربط 1925 al-khwarizmi engineering journal al-khwarizmi engineering journal,vol. 12, no. 3, p.p. 1925 (2016) helical piles embedded in expansive soil overlaying sandy soil bushra suhale al-busoda* hassan obaid abbase** *,** department of civil engineering/ college of engineering/ university of baghdad e-mail:albusoda@yahoo.com e-mail:temimi71@yahoo.com (received 8 november 2015; accepted 19 april 2016) abstract in this study, the behavior of square helical piles models (5×5) mm2 embedded in expansive soil bed overlaying a layer of sandy soil was investigated. the sand layer 200mm thickness was compacted into four sub layers in a steel container with diameter 400mm in size. sandy soil layer was compacted into two relative densities 40% and 80%. the bed of expansive soil 300mm thickness was compacted into six sub layers on sandy soil layer. model tests are performed with helical pile length 350mm, 400mm and 450mm and with helix diameter 15mm and 20mm. also, one helix and double helix were used for these piles. water was allowed to seep from bottom of sandy soil to reach surface of expansive soil through four sand drains around helical pile. this study revealed that the upward movement of helical piles decreases with increasing depth of embedment in the sandy layer, helix diameter and number of helix. the increase in these parameters provides anchorage against uplifting. helical piles embedded in sandy soil of relative density (40%) have uplift movement more than helical piles of relative density (80%). keywords: helical piles, expansive soil, uplift movement. 1. introduction foundations on expansive clay are frequently subjected to severe movements arising from moisture changes within the clay with consequent cracking and damage due to distortion. piles have been used extensively for foundations in swelling soils in order to anchor the structure down at a depth where change in moisture content are negligible, so that movements of the structure are minimized [8]. the modern square shaft helical piles has been refined in shape and size and adapted to high strength low alloy steels to produce the deep foundation system in use nowadays [7]. helical piles are a factorymanufactured steel foundation system consisting of a central shaft with one or more helix–shaped bearing plate [11]. any deep foundation, such as helical pile must embed and transfer load through the active zone to stable soil below. the active zone is defined as that zone or depth of seasonal moisture change, sometimes also called the depth of wetting. it is the depth or zone where soil expansion or shrinkage forces adversely affect deep [9]. foundation is not sufficiently installed below the active zone, as moisture content changes, heave or shrinkage forces will be applied to the deep foundation which may cause it and the structure above to move. the present work aims is to investigate the behavior of model helical piles embedded in expansive soil overlaying a layer of sandy soil. the parameters investigated are the length of helical pile, relative density of sandy soil, number of helix and helix diameter. 2. material properties 2.1. expansive soil the expansive soil used in this study was artificially prepared by mixing iraqi bentonite from al-anbar governorate / bushayrah valley, 35 kilometers southern al-waleed military base from a depth of three and a half meters from bushra suhale al-busoda al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 1925 (2016) 20 natural ground level, with sandy soil. in order to increase the permeability of prepared soil and to facilitate and accelerate saturation process, several trial mixes of bentonite-sand were performed. a ratio of expansive soil to sand of (4/1) was selected. at this ratio, the soil remains highly expansive and its permeability is increased. the results of laboratory tests are shown in table (1). according to the astm standard soil classification, the soil is classified as (ch). 2.2. sandy soil this soil is used beneath the expansive soil, which is used as a stable zone, is poorly graded fine clean sand obtained from site in al-khalis city. prior to testing, the sandy soil is dried in laboratory by drying oven at 105 oc for 24 hr. then sieved on the sieve no.40 to remove the coarse particles. laboratory tests were conducted on the sandy soil to determine the physical, mechanical, and chemical properties. the results of laboratory tests are shown in table (2). it should necessary to mention here; that the direct shear test was performed at relative density of 80% which correspond to dry unit weight equal to (15.9) kn/m3. according to the astm standard soil classification, the soil is classified as poorly graded sand (sp). 2.3 model piles thirty two of steel helical piles with length ranging from 300mm to 450mm and square solid section with dimension (5x5)mm2 were manufactured from high resisting steel as shown in plate (1). the experiment program is carried out on single pile with different length, helix diameter and number of helix. two diameters of helix plate are used 15mm and 20 mm with thickness 3mm. plate. 1. different types of helical piles used in this study. 2.4. soil container soil steel container was made using a 4mm thickness plate with internal diameter of 40cm and height of 60cm. the base of container is supported by four steel rigid legs and contains a hole of 2.5cm diameter in the center of the bed to connect the valve. this valve is connected to tank to perform the saturation process of soil from bottom to top of soil. the water level in the tank must be usually kept 10cm more than the surface of soil. the containers were painted with two coats of anti-rust paint and two layers leady base to resist corrosion during test period. plate (2) shows the containers and frames used in testing models. plate. 2. frames and containers tests. bushra suhale al-busoda al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 1925 (2016) 21 table 1, physical properties of expansive soil. value soil property standard test name 2.78 specific gravity (gs) (astm d-854) specific gravity 102 liquid limit (l.l)% (astm d-4318) atterbeg limits 43 plastic limit (p.l)% 59 plasticity index (p.i)% 53 clay % (astm d-422) grain size analysis 27 silt% 20 sand% ٠ gravel% ch unified soil classification system (uscs) 13.1-13.4 maximum unit weight (kn/m3) (astm d-1557) standard compaction and (3/4) energy of standard 18-19 optimum moisture content (o.m.c)% 260 swelling pressure (kpa) (astm d-4526) swelling pressure table 2, summary of sandy soil properties. test name standard property value grain size analysis (sieve analysis) (astm d-422) coefficient of uniformity (cu) 2.5 coefficient of curvature (cc) 1.23 unified soil classification system (uscs) sp specific gravity (astm d-854) specific gravity (gs) 2.69 direct shear (astm d-3084) cohesion(kn/m2) 0 angle of internal friction(φ°) 37 2.5. testing procedure the soil bed was prepared on a dry density of 1.335gm/cm3 which corresponds to a water content of 2% dry of optimum, from the compaction curve of 3/4 standard proctor for the expansive soil. four sand drains were formed around the pile using thin walled steel tube (10 mm diameter and 300mm length). the sand drains were spaced 50mm from the pile (center to center). the required amount of the oven dried natural sandy soil passing sieve no.40 was prepared at two dry unit weight. the first unit weight is equal to 15.9 kn/m3 to which represents the dense state. the second dry unit weight is equal to 14.5kn/m3 which represents loose state. torque is applied gradually to driven helical pile in the center of surface of expansive soil bed to required depth. enough care and control should be taken to keep vertical line of helical pile. 4. results and discussion models tests are performed on steel piles without helix plates and have the same square cross section (5×5) mm2 of helical piles to assess the degree of efficiency gained after introducing helical piles. figures (1) and (2) shows the effect of the length of helical piles on its maximum uplift movement. in general, the maximum uplift movement of piles decreases with increasing its length. when full mobilization of the uplift movement is achieved, the deeper soil will tend to restrain the upper movement and increase the anchorage resistance of the pile. it can be seen from figures (1) and (2) that helical piles embedded in sandy soil of relative density equals (40%) have uplift movement more than helical piles embedded in sandy soil of relative density equals (80%). the efficiency of helical piles embedded to sandy soil decrease with the increase of the relative density. the installation of helical piles in loose sandy soil leads to be denser and increases shear strength. on the contrary, if helical pile is installed in dense sandy soil lead the soil to be disturbed and decrease shear strength. bushra suhale al-busoda al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 1925 (2016) 22 also, it can be noticed from figures (1) and (2) that the maximum uplift movement decreases with increasing helix diameter. this behavior may be attributed to the increase the surface area of part of helical pile embedded in sandy soil that causes increasing in anchorage resistance. it can be noticed also from figures (1) and (2), the maximum uplift movement decreases with increasing number of helix. figures (3) and (4) illustrates the dimensionless ratio of the maximum uplift movement of pile to the maximum uplift movement of soil surface (spmax/ssmax) plotted against ls/h ratio (depth of embedment of the pile in sandy soil layer to the thickness of expansive soil) for two relative densities 40%,80% of sandy soil. the relationship is for helical piles with single and double helix with two ratios of diameter of helix plate/ equivalent diameter of square cross section of shaft of helical pile (dh/dpe) 2.68 and 3.57. a unique relationship was observed within a limited number of model tests performed and for specified soil. extrapolating the results indicate the ratio(spmax/ssmax)=0 at different ratios of (ls/h) according to helix diameter and number of helix as shown in table (3). to reflect the required anchorage the required anchorage depth to field conditions, the model test would be more conservative since the applied load was not included in the model tests. however, this depth may be proposed for determining a safe anchorage depth. table 3, analysis of results for required (ls) of case no upward movement of helical piles. required ls (mm) ls/h (r.d.) % dh/dpe no.of helix 306 1.02 40 2.68 single 291 0.97 3.57 204 0.68 80 2.68 single 201 0.67 3.57 234 0.78 40 2.68 double 210 0.70 3.57 174 0.58 80 2.68 double 159 0.53 3.57 fig. 1. variation of maximum uplift movement of helical pile with l/d ratio for different lengths and helix diameters (relative density =40%). fig. 2. variation of maximum uplift movement of helical pile with l/d ratio for different lengths and helix diameters (relative density = 80%). fig. 3. design chart for steel and helical piles in expansive soil embedded in sandy soil with r.d. = 40 %. bushra suhale al-busoda al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 1925 (2016) 23 fig. 4. design chart for steel and helical piles in expansive soil embedded in sandy soil with r.d. =80 %. the pullout load test carried out on helical piles in expansive soil embedded to sand soil to measure the ultimate pullout load capacity with swelling effect. after complete saturation and the swelling of expansive soil is stopped, pullout load is applied on helical piles models and the upward movement is measured. the failure occurs when observing a certain maximum value of pullout load or a large upward movement happened due to small increment of applied load, this load is called failure pullout load. the results of pullout load tests of 32 models are tabulated in table (4). figures (5) to (8) show the variation of pullout load with upward movement for three different ratios of (l/d) 62, 71, 80 and two relative densities of sandy soil 40%, 80%. the pullout load upward movement relations are nonlinear and show similar trend of behavior. the failure pullout load increased with the increasing length, helix diameter, number of helix of helical piles and relative density of sandy soil. this may be attributed to the effect of anchorage action of helical piles and shear resistance mobilized along the cylindrical helical pile soil interface. also, when sandy soil is dense the friction force between helical pile and soil increased which caused high resistance. a comparison between steel piles and helical piles in term of failure pullout load is shown in table (4) it can be seen clearly that the value of failure pullout load of helical piles is approximately (4.7-10.6) times higher than that of steel piles when r.d. of sandy soil 40% and (2.8-8.1) times when r.d. of sandy soil 80%.the results obtained were coinciding with that obtained by [10] and [12]. fig. 5. pullout load -upward movement curves for steel pile without helix (r.d= 40%). fig. 6. pullout load -upward movement curves for helical pile with single helix (dh=20mm, r.d= 40%). fig. 7. pullout load -upward movement curves for steel pile without helix (r.d= 80%). bushra suhale al-busoda al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 1925 (2016) 24 fig. 8. pullout load -upward movement curves for helical pile with single helix (dh=20mm, r.d= 80%). 5. conclusions 1. the upward movement of helical piles for piles embedded in expansive soil overlaying a sandy soil layer decreases with increasing depth of embedment in the sandy layer, helix diameter and number of helix those provide anchorage against uplifting. 2. helical piles embedded in sandy soil of relative density (40%) have uplift movement more than helical piles of relative density (80%). the increase in efficiency of helical piles embedded to sandy soil decrease with the increasing of the relative density. 3. the helical piles resist the soil volume changes more than steel piles. 4. the failure pullout load increased with the increasing length, helix diameter, number of helix of helical piles and relative density of sandy soil. 5. the value of failure pullout load of helical piles is approximately (4.7-10.6) times higher than that of steel piles when r.d. of sandy soil 40% and (2.8-8.1) times when r.d. of sandy soil 80%. 6. for the specified soil used, there is a unique relationship between dimensionless ratio of the maximum uplift movement of pile to the maximum uplift movement of soil surface (spmax/ssmax) and ratio of depth of embedment of the pile in sandy soil layer to the thickness of expansive soil (ls/h) for loose and dense state of sandy soil. this relationship may be used for determining the safe depth required to provide provide a sufficient anchorage. notation d diameter of pile dh diameter of helix plate dpe equivalent diameter of square pile h thickness of expansive soil l length of pile ls embedment length of pile in sandy soil r.d. relative density of soil 6. references [1] astm d422-2007, “standard test method for classification of soils for engineering purposes (unified soil classification system)”. [2] astm d3084-2007, “standard test method for direct shear test of soil under consolidated drained condition”. [3] astm d4318-2007, “standard test method for liquid limit, plastic limit and plasticity index of soils”. [4] astm d4546 (a)-2007, “standard test method for one-dimensional swell or settlement potential of cohesive soils”. [5] astm d1557-2007, “standard test method for laboratory compaction characteristics of soil using standard effort”. [6] astm d854-2007, “standard test method for specific gravity of soil solids by water pycnometer”. [7] black, d., r., and pack, j., s., ''design and performance of helical piles in collapsible and expansive soil in arid regions' 'proceeding of 36th symposium, engineering geology geotechnical eng., univ.of nevada, (2001). [8] hari, p., k., and ramana, v., r., ''pullout capacity of granular anchor piles in expansive soils'' iosr journal of mechanical and civil eng., vol.5, (2013). [9] hargrave, r.l. and thorsyen, r.e. ''helical piers in expansive soils of dallas, texas'' 7th int. conf.on expansive soil, (1993). [10] hamdy, h., a., and walla, e., d., ''the compression and uplift bearing capacities of helical piles in cohesionless soil' 'journal of american science, vol.9, no.12, (2013). [11] john, s., pack and p.e., m., ''performance of square shaft helical pier foundations in swelling soils'', geo-volution, pp.76-85, no.4, (2006). [12] tsuha, c.h.c., and rault, g., ''influence of multihelix configuration on the uplift capacity of helical anchors'', 18th int. conf.on soil mechanics, paris, (2013). �� 3، ا���د����12 ا���ارز � ا���� �� ا���� ���ى ��� ز��ر �� ،25 -19 )2016( ��� ا��.�-, ا���� �� ا��+�و � (" &��� ا)$��'�� &%$�� #�" ط �� ر **1%0 # �� # �س * ���ى ��� ز��ر ��� ا������ /��� ا������ ا������** ، *� %$�اد"!م�� / albusoda@yahoo.com :&ا�-),� ا+�*()و� * temimi71@yahoo.com : ا+�*()و�& ا�-),� ** �� ا��2 �= ط-�0 مa ا�)م@م)%. م�� )٥x٥(<= ھ;ه ا��را�� �8 درا�� 78)ف ا�)�!45 ا���3-�� ذات م0/. م)%. %!%�!د c ��)�8 ��d!e)ا�()%� . م$)و�� %()%� ا� f��% ���م�� ���i �8! ٣٠٠ ا�()%� ا+�(f��% ��d!e %. ٨٠و%٤٠م�� وm*% !���i �8!<� ��-�� ٤٠٠م�� k��i %!ر%. ط-0!ت <= ا�!ء �i,�ى %0/) ٢٠٠ا�)م ���م�� وا�(�rمk ٢٠ م�� و١٥ م�� وs5!et ��3-�� دا5),� %0/) ٤٥٠ م�� و ٤٠٠ م�� و ٣٥٠ا�(�rمk ر�!45 ��3-�� %!ط3ال . %�k ط-0!ت <3ق ا�()%� ا�)م �= ac ط),] ار%. م-!زل رم��� 3iل ا�)��4ةا��!ء اx�y . %37رة اi!د,� و�w!��5 �*@ ر��4ةc\� .e8(,و ���. ا�= ا�()%� مa ا+�ac @e ط),] ا�()%� ا�)م �]�e7ا� (/��= 08@ %!زد,!د ا���] <= ا�()%� ا�)م��� وز,!دة c\� ��-�3��� ا�)�!45 ا�(i ل ھ;ه ا��را�� ان\d aدھ! و"� م�c�3-�� ا��$)و�� . و�ا�)�!45 ا� �= ا�m) مa ا��$)و�� <= ذات ا�*m!<� ا���-�� % ٤٠��� ذات ا�*m!<� ا���-�� <= ا�()%� ا�)مc\� !�)�(i 8٨٠*3ن. % al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 7, no. 1, pp 39 55 (2011) implementation of neural control for continuous stirred tank reactor (cstr) karima m. putrus department of chemical engineering/ university of technology email: karima_cheng@yahoo.com (received 29 april 2010; accepted 20 march 2011) abstract in this paper a dynamic behavior and control of a jacketed continuous stirred tank reactor (cstr) is developed using different control strategies, conventional feedback control (pi and pid), and neural network (narma-l2, and nn predictive) control. the dynamic model for cstr process is described by a first order lag system with dead time. the optimum tuning of control parameters are found by two different methods; frequency analysis curve method (bode diagram) and process reaction curve using the mean of square error (mse) method. it is found that the process reaction curve method is better than the frequency analysis curve method and pid feedback controller is better than pi feedback controller. the results show that the artificial neural network is the best method to control the cstr process and it is better than the conventional method because it has smaller value of mean square error (mse). matlab program is used as a tool of solution for all cases used in the present work. keywords: predictive control, pid control, neural network, nonlinear control, continuous stirred tank reactor. 1. introduction chemical reactors are the most influential and therefore the important units that a chemical engineer will encounter. to ensure the successful operation of a continuous stirred tank reactor (cstr), it is necessary to understand their dynamic characteristics. a good understanding will ultimately enable effective control systems design. the aim of these notes is to introduce some basic concepts of chemical reaction systems modeling and develop simulation models for cstr's. non-linear and linear systems descriptions are derived [1]. chemical process control requires intelligent monitoring due to the dynamic nature of the chemical reactions and nonlinear functional relationships between the input and output variables are involved. cstr is one of the major processing units in chemical engineering; such a problem remains too complex to be solved by the known techniques; therefore, neural networks models can provide good optimal solutions for many applications [2]. control and optimization problems are some of the more difficult applications for ann [3]. the mapping functions that must be learned are generally very complex in nature and the problem constraints that must be satisfied are often conflicting (control problems, typically, require nonlinear time dependent mapping of input signals). neural networks based on adaptive resonance theory are equipped with unique computational abilities that are needed to function autonomously in a changing environment [4]. carpenter et al. implemented a self-organizing and adaptive neural network system in the monitoring and control of the behavior of an industrial / platinum flotation plant (hydrometallurgical process). other network formalisms, namely radial basis function (rbf) and adaptive resonance theory-2 (art2) networks have also been employed for fault this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ karima m. putrus al-khwarizmi engineering journal, vol. 7, no. 1, pp 39 55 (2011) 40 detection, diagnosis and process monitoring task [5, 6]. leonardj et al., whitley et al. and krishnaveni et al. used ann based systems to control patterns estimation for upfc in power flow problem [7, 8, 9]. zhang et al used a locally recurrent neural network to model the ph dynamics in a cstr reactor [10]. petia et al applied a feed forward network in the modeling and control of a fedbatch crystallization process [11]. 1.1. types of feedback controller the block diagram of feedback controller is shown in fig (1). the most important types of industrial feedback controllers include [13]: fig.1. block diagram of feedback controller. a) proportional control sc ctektc  )()( …(1) b) proportional – integral controller most controller loops use (pi) controller; the advantage of this controller is that it has quick response for large error and does not have set point offset. the measured variable can be returned to the set point without excessive oscillation. sc ctektc t dtteck i  0 )()()(  …(2) c) proportional – integral derivative controller (pid) the adjustment of the input variable is accomplished using all three methods: proportional, integral, and derivative. the advantage of (pid) action is that it gives response. the disadvantage is that you have to tune three parameters. sc ctektc t dtteck i  0 )()()(  …(3) 1.2. description of the artificial neural networks model referring to figs. (2 and 3), in the network functions, each neuron receives a signal from the neurons in the previous layer, and each of those signals is multiplied by a separate weight value. the weighted inputs are summed, and passed through a limiting function which scales the output to a fixed range of values. the output of the limiter is then broadcast to all of the neurons in the next layer. so, to use the network to solve a problem, we apply the input values to the inputs of the first layer, allow the signals to propagate through the network, and read the output values [14]. there are two types of artificial neural network: + e m + +c ym ysp controller final control element process measuring device y disturbance variable this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ karima m. putrus al-khwarizmi engineering journal, vol. 7, no. 1, pp 39 55 (2011) 41 output yk x1 w1k x1 w1k activation function f (.) bias bk x1 w1k synaptic weights fig.2. nonlinear model of neuron fig.3. a generalized network. a) nn predictive control the model predictive control method is based on the receding horizon technique. the neural network model predicts the plant response over a specified time horizon. the predictions are used by a numerical optimization program to determine the control signal that minimizes the following performance criterion over the specified horizon [3].                     21 1 1 2 2 jtujtup jtyjty n nu j mpn j …(4) where n1, n2, and nu define the horizons over which the tracking error and the control increments are evaluated. the u variable is the tentative control signal; is the desired response, and ym is the network model response. the p value determines the contribution that the sum of the squares of the control increments has to the performance index. the block diagram in figs (4 and 5) illustrates the model predictive control process. the controller consists of the neural network plant model and the optimization block. the optimization block determines the values of u' that minimize j, and then the optimal u is the input to the plant. the controller block is implemented in stimulant; the neural network plant model uses previous inputs and previous plant outputs to predict future values of the plant output [15]. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ karima m. putrus al-khwarizmi engineering journal, vol. 7, no. 1, pp 39 55 (2011) 42 fig.4. nn predictive control. fig.5. block diagram of the nn predictive control. b) narma-l2 control using the narma-l2 model, you can obtain the controller [14] ...(5) which is realizable for (d ≥2). the following figure is a block diagram of the narma-l2 controller. this controller can be implemented with the previously identified narma-l2 plant model, as shown in figs (6 and 7). therefore, the aim of the present work is to propose (narma-l2 and nn predictive) network, which is used to model the dynamics of the cstr problem and a typical problem that was solved. neural networks are well known for their ability to imitate the skill of experts by capturing knowledge, generalizing non-linear functional relationship between inputoutput variable, and they provide a flexible way of handling complex and intelligent information processing. artificial neural networks (anns) have been shown to be effective as computational processors for various tasks including data compression, classification, combinatorial optimization problem solving, modeling and forecasting, and adaptive control. the neural network predictive controller developed in this paper uses a neural network model of a nonlinear plant to predict future plant performance. the controller calculates the control input that will optimize plant performance over a specified future time horizon. simulation of the neural network based predictive control of the continuous stirred tank reactor is presented. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ karima m. putrus al-khwarizmi engineering journal, vol. 7, no. 1, pp 39 55 (2011) 43 fig.6. block diagram of the narma-l2 control. fig.7. narma l2 control structure. 2. theory 2.1. modeling process scheme a jacketed continuous stirred tank reactor of butru [16] is taken as an example process in the present work which has been used to carry out the exothermic chemical reaction of acetic anhydride with water. a dynamic model for first order cstr is developed to predict the transient responses to normal and abnormal (upsets) conditions using servo technique. the mathematical model obtained using mass and energy balances is used to develop a model for controlling, feed rate, the jacket rate and both feed rate and jacket rate using several control strategies, feedback and neural network (narma-l2, and nn predictive) control for two different scheme. the chemical reaction is: coohcho 322ho2co)3(ch  …(6) figure (8) shows the schematic diagram of jacketed reactor. the anhydride (feed) enters the reactor through control valve (cv1 ) with flow rate (f1) and temperature (t1). the concentration of anhydride in feed stream and reactor are (cno and cn) respectively; while the concentration of the product (acetic acid) is (ca) and the acidity of solution is (ph). the temperature and volume of this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ karima m. putrus al-khwarizmi engineering journal, vol. 7, no. 1, pp 39 55 (2011) 44 reactants in the reactor are (t and v) respectively . the reactor is cooled by water-jacket through control valve (cv2) with hold up of vj. the inlet temperature, outlet temperature and flow rate of cooled water are (tj, tjo and fj) respectively. the inner and surface areas of the reactor are (ai and ao) respectively. the experimental results of this work are taken from the same reference [16]. the properties of the feed solutions and parameters of the reactor are presented in tables (1 and 2) and the approximate correlation of the above reaction is given by: ca = 198.182 exp (-1.849 ph) total mass balance 021  dt dv fff …(7) 21 fff  …(8) mass balance on component (a) dt adc vrt e eacovkafcaocf   1 …(9) heat balance on component (a) dt dt cvttua ecvkhtcftcftcf pjh rt e aorppp      )( 2211 …(10) heat balance on the jacket dt jdt pjcjjvtjthuajtjotjpcjjf   )()( …(11) fig.8. schematic diagram of jacketed cstr process. table 1, properties of the feed solutions at the 250c. material density kg/m3 concentration mole/l ionization constant molecular weight acetic acid 1528 19.1 completel y ionized 40 distillate water 1050 14 1.75*10-5 60.05 table 2, parameters of the reactor of butrus [16]. martial property area for heat exchange 5.33x10-2 (m3) ideal gas constant 8.314 (kj/kmol k) heat of reaction 45000 (kj/ kmol) activation energy 36700 (kj/kmol) overall heat transfer coefficient 1480 ( w/ m2 k) heat capacity for jacket 4.186 (kj/kg k) density of acetic acid 1.05 (kg/m3) density of acetic anhydride 1.08 (kg/m3) density for jacket 997 (kg/m3) feed flow rate 1.83x10-2 (m3/min) distillate water flow rate 1.714x10-5 (m3/min) jacket feed flow rate 0.0235 (m3/min) jacket output flow rate 0.0235 (m3/min) inlet temperature of reactant 298 (k) jacket feed temperature 298 (k) jacket outlet temperature 299 (k) reaction rate constant 9.36 (min-1) concentration inlet 0.999 (kmol/m3) volume of reactor 2x10-3 (m3) volume of jacket 2x10-3 (m3) height of reactor 0.5 (m) this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ karima m. putrus al-khwarizmi engineering journal, vol. 7, no. 1, pp 39 55 (2011) 45 2.2. control schemes 2.2.1 scheme a/ control of the reactant concentration the acetic acid concentration ca was controlled by manipulating the reactant flow rate (f1) as shown in fig.(9). the holdup of reactor was adjusted by using a level controller; hence, the reactant flow rate is kept constant. the transfer function for scheme a is: 14.15 15.0129 )(1    s e sg … (12) the approximate correlation of this relation was established by least squares method which gives the experimental form. fig.9. scheme a of control of reactant concentration. fig.10. scheme b of control of reactor temperature. 2.2.2 (scheme b)/ control of the reactor temperature. in this scheme, the reactor temperature t is controlled by manipulating the cooling water flow rate (f1) as shown in fig.(10). the transfer function for scheme b is: 16.17 15.0173 )(2    s e sg …(13) this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ karima m. putrus al-khwarizmi engineering journal, vol. 7, no. 1, pp 39 55 (2011) 46 2.3. simulation program computer simulation was carried out using matlab. it starts with the creation of a mathematical model and the obtained equations are solved by using an appropriate calculation method. matlab’s graphical user interface (gui) can be used for investigating the static and dynamic behavior and adaptive control of the nonlinear system represented by continuous stirred tank reactor (cstr). there are many types of models; the main categories are real models and computer models. based on this division, also simulation can be done for a real model investigation of its behavior as a result of input stimulation [17]. the importance of computer simulation will grow in the future when computers are faster [18]. 3. results and discussion the first part is to study the dynamic behavior of the system theoretically and plot the step responses where the transfer functions between the controlled variables and manipulated variables are computed from the experimental work of butrus [16]. the second part is to study the closed loop system which is the main aim of this work through applying different control strategies; these strategies are: feedback control, narma-l2 control and nn predictive control. 3.1. dynamic behavior in this section, the dynamic responses are studied for a different step change in the manipulated variable which is the reactant flow rate f1 in order to study the effect of this change on the controlled variable of the acetic acid concentration ca(in terms of ph (scheme a) and the temperature of reactor t (scheme b)). these changes are: (-50 % and -100%) step change in the feed flow rate f1. the responses are shown in figs (11 and 12). these results are obtained by using computer simulation programs. from these figures, it can be seen that the concentration increases and the temperature decreases with the decreasing of the feed flow rate for different step changes. fig.11. transient response of concentration for step change in feed flowrate. 0 0.2 0.4 0.6 0.8 0 10 20 30 40 50 60 time (min) c on ce n tr at io n ( k m ol /m 3) -50% step change -100% step change this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ karima m. putrus al-khwarizmi engineering journal, vol. 7, no. 1, pp 39 55 (2011) 47 -6 -5 -4 -3 -2 -1 0 0 10 20 30 40 50 60 time (min) t em pe ra tu re d if f. ( k ) -50% step change -100% step change fig.12. transient response of reactor temperature for step change in feed flowrate. 3.2. the closed loop system feedback controller is applied using pi and pid controller modes to control the cstr process; therefore, tuning the control parameters (proportional gain (kc), time integral (τi) and time derivative (τd)) must be done first. the optimum values of the controller parameters (kc, τi, τd) are obtained using computer simulation programs based on mean square error (mse). the control tuning is found by two different methods which are process reaction curve (prc) and frequency analysis (bode diagram). a). results of control tuning using pi, pid controller. in this section, pi and pid controller is used to control cstr reactor for the two transfer functions (eq. 13 and 14) as follows: figs (13 and 14) show the bode diagram of the closed loop system for the first and second transfer functions respectively to determine the value of ultimate gain (ku) and ultimate period of sustained cycling (pu) in order to tune the adjusted parameters values for the cstr reactor as shown in tables (3 and 4). on the other hand, figs (15 and 16) show the transient response of different control tuning methods with pi controller mode; while figs (17 and 18) show the (time absolute square error) versus time for the first and second transfer functions respectively. the results in figs (19 and 20) show the transient response of different control tuning methods with pid controller mode; while figs (21 and 22) show the (time absolute square error) versus time for the first and second transfer functions respectively. the control parameters of pi and pid for first transfer function are listed in tables (3 and 4) while the same parameters for the second transfer function are listed in tables (5 and 6). from the comparison of the process reaction curve method with frequency analysis curve method, it is concluded that the tuning by using frequency analysis curve method is worse than process reaction curve method because frequency analysis curve method depends on closed loop system; while process reaction curve method depends on open loop system and also the proportional gains are larger for the process reaction curve method. it is clear that pid mode is better than pi mode because of the good tuning of adjusted parameters values in pid mode which gives the smaller overshoot and makes the system with smaller oscillation and reaches the new steady state value in shorter time and reaches the new steady state value in shorter time. also the area under the curve of the process reaction curve method is lower than the area under the curve of the frequency analysis curve method and values of the mse in the first method are less than those in the second method. the results agree with the work of derar [19]. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ karima m. putrus al-khwarizmi engineering journal, vol. 7, no. 1, pp 39 55 (2011) 48 fig.13. bode diagram of the cstr process. fig.14. bode diagram of the cstr process. fig.15. transient response of the cstr process with pi feedback controller. -50 0 50 m ag ni tu de ( db ) 10 -4 10 -3 10 -2 10 -1 10 0 10 1 10 2 10 3 -90 0 90 180 270 360 p ha se ( de g) bode diagram frequency (rad/sec) 0 2 4 6 8 10 12 -0.5 0 0.5 1 1.5 2 2.5 time (min) p h bode digram process reaction curve -50 -40 -30 -20 -10 0 10 20 30 40 50 m ag ni tu de (d b ) 10 -4 10 -3 10 -2 10 -1 10 0 10 1 10 2 10 3 -90 0 90 180 270 360 ph as e (d eg ) bode diagram frequency (rad/sec) this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ karima m. putrus al-khwarizmi engineering journal, vol. 7, no. 1, pp 39 55 (2011) 49 0 2 4 6 8 10 12 -0.025 -0.02 -0.015 -0.01 -0.005 0 0.005 0.01 0.015 0.02 time (min) ti m e* m ea n sq ua re e rr or bode digram process reaction curve fig.16. transient response of the cstr process with pi feedback controller. fig.17. the relationship between the )time mean square error) and time with pi feedback controller. fig.18. time  mean square error versus time with pi feedback controller. 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 -0.5 0 0.5 1 1.5 2 time (min) p h bode digram process reaction curve 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 -0.04 -0.03 -0.02 -0.01 0 0.01 0.02 0.03 time (min) ti m e* m ea n sq ua re e rr or bode digram process reaction curve this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ karima m. putrus al-khwarizmi engineering journal, vol. 7, no. 1, pp 39 55 (2011) 50 fig.19. transient response of the cstr process with pid feedback controller. fig.20. transient response of the cstr process with pid feedback controller. fig.21. the relationship between the (time mean square error) and time with pid feedback controller . 0 0.5 1 1.5 2 2.5 3 3.5 -0.5 0 0.5 1 1.5 2 2.5 time (min) p h bode digram process reaction curve 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 -0.5 0 0.5 1 1.5 2 time (min) p h bode digram process reaction curve 0 0.5 1 1.5 2 2.5 3 3.5 -0.04 -0.03 -0.02 -0.01 0 0.01 0.02 0.03 time (min) ti m e* m ea n sq ua re e rro r bode digram process reaction curve this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ karima m. putrus al-khwarizmi engineering journal, vol. 7, no. 1, pp 39 55 (2011) 51 fig.22. time mean square error versus time with pid feedback controller. table 3, control parameters of pi controller for first transfer function. control tuning methods controller parameters mse kc τi τd frequency analysis curve 0.9396 0.4943 2.5353*10 ^-4 process reaction curve 0.9971 0.4899 1.0721*10 ^-4 table 4, control parameters of pid controller for first transfer function. control tuning methods controller parameters mse kc τi τd frequency analysis curve 1.2159 0.2966 0.0741 1.1071*10 ^-5 process reaction curve 1.7665 0.3677 0.0544 0.3295 *10 ^-5 table 5, control parameters of pi controller for 2nd transfer function. control tuning methods controller parameters mse kc τi τd frequency analysis curve 0.3045 0.4945 3.6336*10 ^-4 process reaction curve 0.6126 0.4911 1.7094*10 ^-4 table 6, control parameters of pid controller for 2nd transfer function. control tuning methods controller parameters mse kc τi τd frequency analysis curve 0.3941 0.2967 0.0742 5.0057*10 ^-5 process reaction curve 0.9083 0.3679 0.0545 3.4917*10 ^-5 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 -0.04 -0.03 -0.02 -0.01 0 0.01 0.02 0.03 time (min) ti m e* m ea n sq ua re e rro r bode digram process reaction curve this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ karima m. putrus al-khwarizmi engineering journal, vol. 7, no. 1, pp 39 55 (2011) 52 b). results of control tuning using narma-l2 and nn predictive controller. narma-l2 algorithm and nn predictive control are implemented using back-propagation networks in this work, which depends on:  changing the number of neurons in the hidden layer can represent the degree of the complexity of the system.  the ability of input layer to store information was used to represent the dynamic behavior of system by using the tapping delay lines for input/output signals. figs. (23 and 24) show the transient response of narma-l2 and nn predictive control respectively for the first transfer function only. comparing narma-l2 with nn predictive control, it can be seen that the narma-l2 control is better than nn predictive control because the values of the mse in the first method are less than those in the second method. this comparison is listed in table (7). finally the comparisons among feedback control, narma-l2 and nn predictive control for 1st transfer function is listed in table (8). many authors have reported the same results [12, 19]. fig.23. the transient response of narma-l2 control. fig.24. the performance of nn predictive control. 0 1 2 3 4 5 6 7 8 9 10 0 0.2 0.4 0.6 0.8 1 1.2 1.4 time (sec) p h narma-l2 disired output this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ karima m. putrus al-khwarizmi engineering journal, vol. 7, no. 1, pp 39 55 (2011) 53 table 7, comparisons between narma-l2 and nn predictive control transfer function. criteria narma-l2 nn predictive mse 3.4429*10^-6 4.2112*10^-6 training 6.43*10^-3 6.99*10^-3 validation 7.21*10^-4 6.91*10^-3 test 8.45*10^-4 9.87*10^-4 table 8, comparisons among feedback control, narmal2 and nn predictive control for 1st transfer function. controllers mse pid 0.3295 *10 ^-5 pi 1.0721*10 ^-4 narma-l2 3.4429*10^-6 nn predictive 4.2112*10^-6 4. conclusion 1. the process reaction curve method is better than the frequency analysis curve method. 2. pid feedback controller is better than pi feedback controller. 3. implementation of artificial neural network is the best method to control the continuous stirred tank reactor (cstr). 4. the narma-l2 control is better than nn predictive control 5. finally the network is successfully used to model and solve the cstr problem keeping the system at its optimum. notation a magnitude of change ah area of heat transfer ca0 inlet concentration of acetic anhydride ca outlet concentration of acetic anhydride d modeling error( ) f volumetric flow rate of distillate water f2 volumetric flow rate of acetic anhydride gc(s) transfer function of controller gd(s) transfer function of disturbance h nonlinear activation function l linear activation function m number of previous input m model n number of the previous output neto the weighted sum of the inputs p plant k discrete time instant k proportional gain k the integral decreasing factor kp gain of the process q number of patterns in training set reactor output neural model output desired output of the plant set point the output of network n1 [.] the output of network n2 [.] y output variable v volume of tank sgn sigmund function s laplacian variable t time tcl(s) transfer function of close loop t temperature of reactor t1 inlet temperature of reactant t2 outlet temperature of reactant tj0 inlet temperature of coolant tjj outlet temperature of coolant td time delay 5. references [1] willis m.j., dept. of chemical and process engineering and process engineering, university of newcastle, march, (2000). [2] himmelblau d. m. (1978) fault detection and diagnosis in chemical and journal of theoretical and applied information technology © 2005 2008 jatit. all rights reserved.www.jatit.org, [3] petrochemical processes, elsevier, amsterdam. patterson d. w, "artificial neural networks theory and applications", prentice hall simon & schuster (asia), singapore pg 220, (1996). this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ karima m. putrus al-khwarizmi engineering journal, vol. 7, no. 1, pp 39 55 (2011) 54 [4] carpenter g. a and grossberg s.),"the art of adaptive pattern recognition by selforganizing neural networks, ieee computer, pp 77-88, (1988). [5] carpenter g. a., grossberg s. and rosen d. b," fuzzy art: fast stable learning and categorization of analog input pattern by an adaptive resonance system", neural networks, vol. 4, pp 59-71, (1992). [6] aldrich c., moolman d. w and van deventer j. s; "monitoring and control of hydrometallurgical process with selforganizing and adaptive neural net systems", comput. chem. engrg, vol. 19 pp s803-s808, (1995). [7] leonard j. a and kramer m. a," radial basis function networks for classifying",(1991). [8] whitley j. r. and davis j. f., a," similaritybased approach to interpretation of sensor data using adaptive resonance theory", comput. chem. engrg. vol. 18, pp 637-661, (1994). [9] krishnaveni k and tulasi r.d, "ann based control patterns estimator for upfc used in power flow power", journal of theoretical and applied information technology, pg 4549, (2007). [10] zhang j. and julian a.,"a sequential training strategy for locally recurrent neural networks", (1994). [11] petia g. and sebastiao f., "application of feed forward neural network in modeling and control of a fed-batch crystallization process", proceedings of world academy of science, engineering and technology, vol. 12 pg 65-70, issn 1307-6884, (2006). [12] anna vasičkaninová and monika bakošová, "neural network predictive control of a chemical reactor", acta chimica slovaca, vol.2, no.2, 21 – 36, (2009). [13] luyben m. l. and lnybem w. l.," essentials of process control", mcgraw hill, new york. (1997). [14] haykin .s. ,"neural network a comprehensive foundation" second edition prentice hall international .inc hamilton .ontario .canada, (1999). [ 1 5 ] montandon a. g., borges r. m. and henrique h m., "constrained nonlinear model predictive control for practical application". school of chemical engineering /federal university of uberlandia. mg. brazil, (2007). [16] butrus k. m., "on-line computer control of a continuous stirred tank reactor", ph. d., thesis, university of technology, (1999). [17] jiří vojtěšek, petr dostál, "program for simulation of a continuous stirred tank reactor in matlab’s gui", 22nd european conference on modeling and simulation, ecms, (2008). [18] ingham, j., dunn, i. j., heinzle, e., přenosil, j. e., "chemical engineering dynamics. an introduction to modeling and computer simulation", second completely revised edition, vch verlagsgesellshaft, wilhelm, (2000). [ 1 9 ] derar i. a., "implementation of neural control for neutralization process", ms. thesis, university of technology, (2009). this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ 55 ، صفحة1، العدد 7لخوارزمي الھندسیة المجلد مجلة ا طرسبكریمھ مروكي 39 )2011( 55 استخدام نظام السیطره بالشبكھ العصبیھ للسیطره على مفاعل ذو الخلط المستمر طرسبكریمھ مروكي الحامعھ التكنولوجیھ /قسم الھندسھ الكیمیاویھ karima_cheng@yahoo.com : االلكتروني البرید الخالصة ن cstr)( كیمیاوي مستمر جید الخلطالسلوك الدینامیكي وطرق السیطرة لمفاعل البحث ھو دراسة إن الھدف من ھذا ة م واع مختلف وذلك باستخدام أن دي وعین و )pidو pi ( المسیطرات مثل المسیطر التقلی بیة بن بكة العص یطر الش ا ( مس ؤي (و )نارم زان ذو ). التنب ي للخ ل الریاض ل المودی م تمثی د ت وق . لخلط المستمر بدالة تحویل من الدرجة األولى مع تأخیرا رات تم توصیف ر متغی یطر بط ا یالمس ین ھم اد process reaction curve methodو frequency analysis curve methodقتین مختلفت إلیج , kcأفضل قیم للمعامالت i  , d .أللخطو تم استخدام معیار متوسط التربیع (mse) كأساس للمقارنة بین الطریقتین أعاله. ع للخط cstrالشبكة العصبیة الصناعیة ھي أفضل طریقة للسیطرة على ال ط التربی ار متوس ك الن معی ة و ذل رق التقلیدی ل أوھي أفضل من الط م . اق ت . االتل في جمیع الحفي ھذا البحث كأداة للح matlabاستخدام برنامج this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ 5260 al-khwarizmi engineering journal,vol. 12, no. study the effect of different reinforcements on the damping properties of ibtihal abed al *,** department of (received 16 abstract in this research, damping properties study the effect of reinforcements on the damping ratio in this research. the first stage included preparing binary blends of epoxy (ep) and different weight percentages of polysulfide rubber (psr) (0%, 2.5%, 5%, 7.5% and 10%). it was the best percentage, which gives the matrix is that; it mediates between the brittle properties of epoxy and the flexible properties of a blend matrix with highest percentage of psr. the second stage included reinforcing the best blend matrix of epoxy matrix with the best percentage of polysulfide short fibers (carbon& glass) separately and randomly. the volume percentages of fibers were (2.5%, 5%, 7.5%, and 10%). the third stage included reinforcing different weight percentages of nano-parti (0.5%, 1%, 1.5%, and 2%). the experimental result damping ratio. as for reinforcement materials, they decreased the damping ratio, where glass fiber composites have significantly higher damping ratio than other composites. keywords: composite materials, epoxy, polysulfide, dampi 1. introduction damping is an influence within or upon an oscillatory system that has the effect of reducing, restricting or preventing its oscillations, where this system is under cyclic stress. the damping properties of composites are a function of the adhesion between the filler and the matrix. good filler-matrix interaction reduce energy dissipation via damping. the proportion of damping that occur in the oscillating system can be expressed by a factor called damping ratio. the damping ratio is a measure describing how dissipati oscillating system after a disturbance, where the oscillating system exhibit oscillatory behavior when it disturbed from its position of static equilibrium [1-2]. khwarizmi engineering journal,vol. 12, no. 3, p.p. 5260(2016) study the effect of different reinforcements on the damping properties of the polymer matrix composite ibtihal abed al-razaq* mustafa ziyara shamukh department of mechanical engineering / university of technology **e-mail: mutafaziara@outlook.com 16 november 2015; accepted 22 february 2016) in this research, damping properties for composite materials were evaluated using logarithmic decrement method to study the effect of reinforcements on the damping ratio of the epoxy matrix. three stages of composites were prepared in this research. the first stage included preparing binary blends of epoxy (ep) and different weight percentages of polysulfide rubber (psr) (0%, 2.5%, 5%, 7.5% and 10%). it was found that the weight percentage 5 the best mechanical properties for the blend matrix. the advantage of this blend matrix is that; it mediates between the brittle properties of epoxy and the flexible properties of a blend matrix with highest percentage of psr. the second stage included reinforcing the best blend matrix of epoxy matrix with the best percentage of polysulfide resulted from the previous stage), by different volume percentages of on& glass) separately and randomly. the volume percentages of fibers were (2.5%, 5%, 7.5%, and 10%). the third stage included reinforcing the blend composites with highest percentages of carbon and glass particles (red mud& fly ash) separately. the weight percentages of particles were (0.5%, 1%, 1.5%, and 2%). the experimental results showed that blending polysulfide rubber damping ratio. as for reinforcement materials, they decreased the damping ratio, where glass fiber composites have significantly higher damping ratio than other composites. composite materials, epoxy, polysulfide, damping ratio, fibers, nano-particles. an influence within or upon an oscillatory system that has the effect of reducing, restricting or preventing its oscillations, where this system is under cyclic stress. the damping properties of composites are a function of the and the matrix. good matrix interaction reduce energy dissipation via damping. the proportion of damping that occur in the oscillating system can be expressed by a factor called damping ratio. the damping ratio is a measure describing how dissipating an oscillating system after a disturbance, where the oscillating system exhibit oscillatory behavior when it disturbed from its position of static the use of composite materials in many structural applications due to their high specif stiffness and strength has attracted interest in methods for improving the damping performance of these structures. it has been found that the damping of composites depends on the micromechanical properties of the constituent materials, which are represented by material and additives. the composite damping exhibits an opposing trend to stiffness and flexibility that gained by the addition of reinforcements, being increase with added flexible properties, and decrease with stiff properties thus there is a need to develop integrated mechanics models for the analysis of structural components which are capable of describing the global structural response by correlating the al-khwarizmi engineering journal (2016) study the effect of different reinforcements on the damping the polymer matrix composite mustafa ziyara shamukh** university of technology ) using logarithmic decrement method to . three stages of composites were prepared in this research. the first stage included preparing binary blends of epoxy (ep) and different weight percentages of weight percentage 5% of polysulfide . the advantage of this blend matrix is that; it mediates between the brittle properties of epoxy and the flexible properties of a blend matrix with the highest percentage of psr. the second stage included reinforcing the best blend matrix of epoxy-polysulfide (the blend ), by different volume percentages of on& glass) separately and randomly. the volume percentages of fibers were (2.5%, 5%, 7.5%, and blend composites with highest percentages of carbon and glass fiber, by . the weight percentages of particles were rubber with epoxy increased the damping ratio. as for reinforcement materials, they decreased the damping ratio, where glass fiber composites have the use of composite materials in many ions due to their high specific stiffness and strength has attracted interest in methods for improving the damping performance of these structures. it has been found that the damping of composites depends on the micromechanical properties of the constituent represented by the matrix . the composite damping exhibits an opposing trend to stiffness and flexibility that gained by the addition of reinforcements, being increase with added flexible properties, and decrease with stiff properties. thus there is a need to develop integrated mechanics models for the analysis of structural components which are capable of describing the global structural response by correlating the ibtihal abed al-razaq al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 5260(2016) 53 damping characteristics of the structural components to the parameters of the basic constituent materials (matrix material and reinforcements) [3-4]. epoxy resins are belong to the principal polymer under the term thermosetting resins. epoxy resins are widely used as structural adhesives, matrices in fiber-reinforced composites, and coatings for metals because of their excellent properties such as high tensile strength and modulus, easy processing, good thermal and chemical resistance, and dimensional stability [5]. however, like other thermoset resins, the crosslinking character of cured epoxies produces a highly undesirable property: they are relatively brittle, having poor resistance to crack initiation and growth. this lack of toughness severely effects the performance of these thermoset in almost all applications. to address this defect, it has been used a technology that permits some thermosets to be toughened by the addition of a second elastomeric phase, such as artificial rubber. this helped to flexibilize the brittle thermoset matrix and increase the fracture energy [6-7]. improving fracture toughness will lead to significantly improved performance when used as is, and will also improve the damage initiation threshold and long term reliability for fiber reinforced composites. there are different reactive liquid elastomers which are used to modify or toughen epoxy resins [8]. liquid polysulfide elastomer is one of the most important reactive modifiers for epoxy resin. polysulfide modified epoxy adhesive systems are widely used in the construction, electrical and transportation industries. since polysulfide is a very flexible elastomer, addition of liquid polysulfide elastomer to epoxy resin gives good damping properties, flexibility and impact strength to epoxy matrix [910]. however, the addition of polysulfide rubber to modify epoxy systems disrupts the most desirable properties of epoxy resin. they reduce the elastic modulus and tensile strength, and the glass transition temperature (tg), while improving damping properties [11]. the weak fracture toughness of many thermosets frequently limits their application areas in which they can be used. considerable efforts had been made in the past to improve fracture toughness of polymers through chemical modification or by incorporation of special additives such as liquid rubbers, elastomers, plasticizers, or fibers reinforcing agents. in the case of thermoset resins, which are normally liquid in uncured state, fibers and particles reinforcements have become an important means of increasing the strength, modulus and impact toughness of such resins. fibers reinforcement used usually with thermosets as short fibers. common types of short fibers are carbon and glass [12-13]. composites with particles as reinforcement are likely to overcome the cost barrier for wide spread applications in roadway products, automotive, and small engine applications. among various types of particles used, fly ash and red mud are the most inexpensive and low-density reinforcements available in large quantities as solid waste. particles reinforcement used to improve various properties of selected matrix materials, including stiffness, strength and wear resistance and reduce the density [14-15]. this paper discusses the effects of combining the benefits of adding polysulfide rubber and two types of reinforcements (fibers and particles) to the epoxy matrix and study their effect on the damping properties of the thermoset matrix. 2. experimental procedure 2.1. materials the blend matrix system consists of epoxy resin and polysulfide rubber. epoxy is thermoset resin containing of two or more epoxide group, which are composed of oxygen atom linked with two atoms of carbon. epoxy group linked chemically with the other molecules to form three-dimensional cross-linked thermoset structures. the type of epoxy used in this research is (quickmast 105® (dcp)) manufactured by commercially produce from quick mast company .the hardener from the same company mixed with the epoxy resin in the ratio of 3:1, and the interaction between them occurs at room temperature, the name of this interaction is (addition reaction), and epoxy properties are shown in table (1). as for polysulfide rubber, which are a class of chemical compounds containing chains of sulfur atoms, provided as a white dough, where it turns into a form of elasticity by adding pbo2 (black dough) in the ratio of 1:16 with a density ratio (1.35) gm/cm3. polysulfide rubber properties are shown in table (2). reinforcement materials must provide two main advantages, which are: high strength and low ductility to improve the matrix material. the most common methods of reinforcement are reinforcing by fibers and particles. carbon and ibtihal abed al-razaq al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 5260(2016) 54 glass fibers have been used to reinforce the blend matrix. it cut to lengths ranging between (10-14 mm) with diameter limits of (10-14 µm) produced by (grace cemfiber company). table (3) shows the physical and mechanical properties of carbon and glass fibers. nano-particles of red mud and fly ash were used as a reinforcement material in this research. table (4) shows the physical and mechanical properties of red mud and fly ash particles. table 1, physical and mechanical properties of epoxy resin [16]. test method typical results compressive strength (mpa)(min.) 70.0 at 20 °c tensile strength (mpa)(min.) 30.0 at 35 °c flexural strength (mpa)(min.) 63.0 at 35 °c young modulus in compression (gpa) 16 hardness (shore d)(min.) 72 impact strength (charpy) kj/m2 4.4 density (g/cm3) 1.004 table 2, physical and mechanical properties of polysulfide rubber [17]. test method typical results general chemical structure -50 to 95 service temperature (°c) 1:16 mixing ratio 1.35 density (g/cm3) 292 tg (°c) 22 39 hardness (shore a) 126 412 ultimate elongation (%) 0.74 0.91 tensile strength (mpa) -50 to 95 table 3, mechanical and physical properties of carbon and glass fibers [18]. typical results fiber carbon glass young's modulus gpa 105 13 poisson's ratio 0.20 0.22 tensile strength gpa 2.4 2 density g/cm3 1.8 2.55 thermal conductivity w/m.k 76 230 table 4, mechanical and physical properties of red mud and fly ash particles [19-20]. typical results particles red mud fly ash young's modulus gpa 30 25 density g/cm3 3.26 2.4-2.8 poisson's ratio 0.341 0.45-0.65 diameter µm 0.7-0.9 1.5-2.5 2.2. molds and specimens preparation composites tend to be high-adhesion, so it should use molds made from materials have moderate strength and toughness. glass has been used in this research to prepare the molds. the mold prepared with dimensions of (16 × 8 × 1.2) cm3, as shown in figure (1). the mold must be cleaned and lubricated the inside walls of the mold with vaseline and nylon paper (fabloon) to prevent the adhesion between the mold and polymeric material. this will ensure to get regular distribution, smooth surface, and no defects. the mixture poured in the mold by hand lay-up molding from one side only to eliminate the entrapment of air. after the solidification process be completed within 24 hours in the room temperature, the molded extracted from the mold, then it cut into a standard specimen dimensions. fig. 1. the shape of the mold. 2.3. composites preparation three stages of composites were prepared in this research. the first stage included preparing samples of epoxy resin and different blend matrices of epoxy-polysulfide. the weight percentages of polysulfide rubber in the matrix resin were (0%, 2.5%, 5%, 7.5%, and 10%).the polymeric blend matrix presented by mixing the resins of both epoxy and polysulfide rubber without their hardeners via magnetic stirrer model (no 690/1) shown in figure (2), for 3-4 hours ibtihal abed al-razaq al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 5260(2016) 55 until it became homogenous. the use of the magnetic stirrer in the preparation of composites to reduce the bubbles arise during the mixing process. hardeners of epoxy and polysulfide were added in the mixture of resins. the final mixture blended for a half hour by manual mixing. after the mixture became homogeneous enough, it poured into the mold and it left in room temperature for completing the solidification. after the molded cut into standard samples, the damping test conducted on them using logarithmic decrement method and integrated system of devices and software programs. from the obtained results of the first stage, the best percentage of polysulfide will be identified. the second stage included reinforcing the best blend matrix of epoxy-polysulfide (the blend matrix with the best percentage of polysulfide from the previous stage), by different volume percentages of short fibers (carbon& glass) separately and randomly. the volume percentages of fibers were (2.5%, 5%, 7.5%, and 10%). fibers added with the obtained blend matrix into the mold with good distribution and mixing. the third stage included reinforcing blend composites with highest percentages of carbon and glass from the previous stage, by different weight percentages of nanoparticles (red mud& fly ash) separately. the weight percentages of particles were (0.5%, 1%, 1.5%, and 2%). particles mixed with the obtained blend matrix (the blend matrix with the best percentage of polysulfide from the first stage), and then fibers added with this mixture into the mold. the same practical steps of the first stage conducted on the second and third stages. fig. 2. magnetic starrier. 2.4. damping test a damping capacity of composites was determined at a laboratory temperature (22 ± 2) c°, using logarithmic decrement method and integrated system of devices and software programs as shown in figure (3). the composite samples (length 145 mm, width 45 mm, thickness 10 mm) were used as cantilever beams. figure (4) shows the specimen of the damping test. fig. 3. damping test setup with assembled sample. .damping test specimen. 4fig. 2.4.1. damping system devices (a) accelerometer an accelerometer is a device that measures the motion response of vibrating system. this apparatus is of type (kistler -4371) with sensitivity 9.8 mv/g as shown in figure (5). accelerometer are extensive used for measuring vibration, as well to record earthquakes, the velocity and displacement are obtained by integration from the record of accelerometer. fig. 5. the accelerometer. (b) amplifier the amplifier device that used in this research is of type (nexus 7749), as shown in figure (6). ibtihal abed al-razaq the amplifier used to increases the power of a signal that received from the accelerom then give the resultant signal to the dig oscilloscope. fig. 6. the amplifier device (c) oscilloscope the oscilloscope device is a type of elect test instrument used for displaying the received signal from amplifier. the oscilloscope that used in this research is of type (gds maximum frequency 100 mhz. it contains a screen to display the oscillating wave that received from the amplifier as a si shown in figure (7). fig. 7. the oscilloscope device . 2.4.2. measurement of damping there are various methods to measure the damping ratio of an oscillating sys depending on the response of the system expre as a function of time or frequency, and that meaning time-response methods and freq response methods. the examples of the ti response methods are logarithmic decrement al-khwarizmi engineering journal, vol. 12, no. 56 ses the power of a ved from the accelerometer, and the resultant signal to the digital storage the amplifier device. oscope device is a type of electronic ng the received scope that used (gds-810) with z. it contains a ng wave that ifier as a sign wave, as the oscilloscope device. damping there are various methods to measure the g system, which ding on the response of the system expressed quency, and that nse methods and frequencyexamples of the timegarithmic decrement method, hysteretic loop method, and step method, while the examples of the frequ response methods are band magnification-factor metho 2.4.2.1. logarithmic decrement method this is probably the most popular time response method used to deter when a single-degree system with viscous da disturbance or impulse input, where its res takes the form of a time dec the logarithmic decrement method. ratio can be estimated from a free wave using equations below: � � �� �� �� � �� ��� then the damping ratio can be obtained from the equation below: � � √������ fig. 8. logarithmic decrement method 2.4.3. method of damping test the specimen was treated as materials with cantilever beam configuration with sufficient length for fixing the beam. accelerometer fixed in the upper surface of the free edge of the specimen, the specimen were subjected to impulse force by a test hammer. impulse testing of behavior of mechanical structure includes beating the test sample with the hammer, and measuring the resultant motion by accelerometer, which is used motion response, and then transfer it to the amplifier device to increases the power of a signal that received from the accelerometer, and then give the resultant signal to the digital storage, which displays the received signal from khwarizmi engineering journal, vol. 12, no. 3, p.p. 5260(2016) retic loop method, and step-response method, while the examples of the frequencyresponse methods are bandwidth method and factor method. decrement method ably the most popular timeonse method used to determine damping ratio. degree-of-freedom oscillatory system with viscous damping is excited by a ance or impulse input, where its response takes the form of a time decay. figure (8) shows ment method. the damping ated from a free-decay recorded wave using equations below: …(1) then the damping ratio can be obtained from the …(2) logarithmic decrement method. method of damping test treated as self-supporting materials with cantilever beam configuration with sufficient length for fixing the beam. the fixed in the upper surface of the specimen, as shown in figure (9). the specimen were subjected to impulse force by test hammer. impulse testing of the dynamic behavior of mechanical structure includes beating the force-instrumented hammer, and measuring the resultant motion by accelerometer, which is used to measure the and then transfer it to the amplifier device to increases the power of a signal that received from the accelerometer, and then give the resultant signal to the digital storage, which displays the received signal from ibtihal abed al-razaq al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 5260(2016) 57 amplifier. the oscilloscope has been connected with a computer by using the serial connection, which adjusts the signal and convert the acceleration into displacement information. the resultant signal from the oscilloscope appears on the computer by using sig-view program, where using logarithmic decrement method to calculate the damping ratio from the response signal obtained from sig-view program. fig. 9. the setup of the specimen for damping test. 3. results and discussion the results of the three stages that have been obtained from the damping test will be discussed and represented in graphic curves in order to identify the properties of materials. 3.1. stage i: epoxy and epoxy-psr blends the experimental results shown in figure (10) showed that the damping ratio increased with the increase of polysulfide percentage. therefore, when blending (2.5%, 5%, 7.5%, 10%) of ps with epoxy caused an increase in damping ratio about (21.59%, 53.41%, 72.72%, 102.27%) than epoxy resin value. due to low mechanical properties of polysulfide rubber, the addition of polysulfide with the brittle thermoset matrix increased the flexibility and improves the damping properties of the blend matrix. the resultant blend matrix will be able to dissipate and absorb the kinetic energy, where this mean reduction in vibration's amplitude and increase in damping ratio. fig. 10. effect of psr weight fraction on damping ratio. 3.2. stage ii: epoxy-psr blend matrix/ fibers the experimental results shown in figure (11) showed that, the damping ratio decreased with the increase of carbon and glass fiber percentage. the addition of (2.5%, 5%, 7.5%, 10%) of carbon and glass fibers with (epoxy+5% psr) blend matrix decreased the damping ratio by about (-19.25%, 29.62%, -41.22%, -50.37%) for carbon fibers composites and (-14.07%, -22.96%, -32.59%, 39.25%) for glass fibers composites. this is due to the fact that, the good fibers distribution in blend matrix led to better adhesion between fibers and the blend matrix, which affect the toughness increment of composites and resulted in less sliding between interfaces, and thus leads to dissipate less energy and decrease damping ratio. it was also noted that the glass fibers composites have significantly higher damping ratio than carbon fibers composites with equivalent volume fraction of fibers reinforcement. 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2 0 2.5 5 7.5 10 12.5 d am p in g ra tio psr weight fraction (%) epoxy ibtihal abed al-razaq al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 5260(2016) 58 fig. 11. effect of fibers volume fraction on damping ratio. 3.3. stage iii: epoxy-psr blend matrixfibers/ particles the experimental results shown in figures (12) and (13) showed that, the damping ratio decreased with the increase of red mud and fly ash particles percentage. the addition of (0.5%, 1%, 1.5%, 2%) of red mud particles with (epoxy+ 5% psr+ 10% carbon and glass fibers) decreased the damping ratio by about (-5.97%, -23.88%, -37.31%, 50.74%) for carbon fiber composites and (-9.75%, -23.17%, -30.48%, -43.90%) for glass fibers composites. for fly ash particles, the addition of (0.5%, 1%, 1.5%, 2%) of fly ash particles with (epoxy+5% psr + 10% carbon and glass fibers) decreased the damping ratio by about (-23.86%, 46.26%, -58.20%, -74.62%) for carbon fiber composites and (-17.07%, -31.70%, -50%, 53.65%) for glass fibers composites. this was due to the fact that, the good particles distribution in the blend matrix led to better adhesion between particles and the blend matrix, which affected the stiffness increment of composite materials and resulted in less sliding between interfaces, and thus leads to dissipate less energy and decrease the damping ratio. it was also noted that glass fiber composites reinforced with fly ash particles have significantly higher damping ratios than other composites of this stage with the equivalent weight fraction of particles reinforcement. fig. 12. effect of red mud particles weight fraction on damping ratio. fig. 13. effect fly ash particles weight fraction on damping ratio. 4. conclusions the most important conclusions that have been reached from this research summarizes as follows: 1the damping ratio of the blend matrix increased with the increase of polysulfide percentage, where the blend matrix with 10% of polysulfide has significantly higher damping ratio than other blends. 2the weight percentage 5% of polysulfide has been selected as the best percentage, which gives the best mechanical properties for the blend matrix. the advantage of this blend matrix is that; it mediates between the brittle properties of epoxy and the flexible properties of a blend matrix with the highest percentage of psr. 3the damping ratio of the blend matrix decreased with the increase of fibers percentage. glass fibers composites have significantly higher damping ratio than carbon 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0 2.5 5 7.5 10 12.5 d am pi ng r at io fibers volume fraction (%) carbon fiber glass fiber 0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0 0.5 1 1.5 2 2.5 d am p in g ra tio red mud particles weight fraction (%) carbon fiber glass fiber 0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0 0.5 1 1.5 2 2.5 d am p in g ra tio fly ash particles weight fraction (%) carbon fiber glass fiber ibtihal abed al-razaq al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 5260(2016) 59 fibers composites with equivalent volume fraction of fibers reinforcement. 4the damping ratio of the blend composites decreased with the increase of particles percentage. glass fiber composites reinforced with fly ash particles have significantly higher damping ratios than other composites with equivalent weight fraction of particles reinforcement. 5. references 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[20] sri tudjono, purwanto, kartika trisna apsari, "study the effect of adding nano fly ash and nano lime to compressive strength of mortar", published by elsevier science, diponegoro university, semarang, vol. 95, pp. 426 – 432, 2014. د12 ��� ا���ارز�� ا��� ��� ا����� د���� قاز��ا � ل����ا� 2016)( 52-60، ��� 3، ا� 60 ���دة ���ا& � ذات أ��س ������ي��� درا�� .-,�� ��اد ا�� ��+ ��* (�اص ا�� **�23�* ز�1رة ��0/ *ا����ل � ا��زاق ����د �� ا����������* *،*� ا�(�)'� ا�&��%�%$�� /#"! ا� � mustafaziara@outlook.com: ا/��&+و�-,+*� ا�** � 4� ا� �ص طر�� �� ��دام ��را�� ��واد ا�����د ����ص ا���ث درا ھذا �م ���� �ب �ا� و��ر��� ا���� � � ا���را�� ا��واد �م ا"داد .ا�����د ���� � ط�ت ا"داد �(��ت ا'و�& ا��ر� . �را�ل �$#ث ا���ث ھذا �� ا�� ��د� $ � ب و"دة �ن ا'��و�� �� ا��و�� -��د �ط�ط ��� �ن وز 7� و$� ان %).١٠و ، %٧.٥، %٥، %٢.٥، %٠(� �� � ا�وز�� c��d أa@? �",� وا�&<'=>;�:9 )�������� $��ة ��ط�ط% ٥ا�*�ef�ا�,%� ��سhا���دة ا j�fk� .ldا��&+ا j�fkا ا�mھ o��* �( /����p�q j ا�%&* r�%d 0� 12ت ا��-�ت ا��e;وا� -"d%,* �)v اtfu �",� ��زوج �j�fk )&+اld ا��ر �*�ef� -�%q .ا� j�f< ?@aا !�u�> c��@> ����wا� �fx+ا�� ld�7(�&+اq�"ا� �fx+ا�� p( رة�&kا�� �*�ef� ،) ا�j�fk ا��&+اld ذو ا��",� ا��p( tfw )=�ط ا�,%� �ا وq&%ز*u v^%ا:%)١٠و ، %٧.٥، %٥، %q)٢.٥�p( �ef&k( ���)x l" ا���ف ا��+q%ن وا�o$�ج ا�7;�+ة x tfu ?ٍd .+ت �د"�م ا���� ا�$��$ �(� � �. q�l" وز��� )p( �ef&k ا��#�:a ا����%*� ا��&�p�=��q �fw ا�xh+ وا�+)�د ا��&=�*+ ( ?�^q�e;?ا���ف �ر�ون وز�6ج، ا��#�ط ا���را�� �4 ا" & �=( jf< نbq أظ +ت ��f�'ا� d:�&�ا� � � أدىط ا��و�� -��د �4 ا'��و���k&ز*�دة �",� ا� tا� .�,"���q �(�2 ا�ا�t �7;�ن �",� أدت��واد ا��د"�م، �� �k&ا��� ،tfuج أظ +ت #�! ا�$oت ا���ف ا��,dان )&+ا f�x ا�����د � � .)�7ر�� q,�#ا��&+اd,�ت � speed control system al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 7282 (2014) design of nonlinear pid neural controller for the speed control of a permanent magnet dc motor model based on optimization algorithm ahmed sabah al-araji department of control and systems engineering / university of technology e-mail: ahmedsas2040@yahoo.com (received 18 december 2013; accepted 24 march 2014) abstract in this paper, the speed control of the real dc motor is experimentally investigated using nonlinear pid neural network controller. as a simple and fast tuning algorithm, two optimization techniques are used; trial and error method and particle swarm optimization pso algorithm in order to tune the nonlinear pid neural controller's parameters and to find best speed response of the dc motor. to save time in the real system, a matlab simulation package is used to carry out these algorithms to tune and find the best values of the nonlinear pid parameters. then these parameters are used in the designed real time nonlinear pid controller system based on labview package. simulation and experimental results are compared with each other and showed the effectiveness of the proposed control algorithm in terms of fast and smooth dynamic response for the speed control of the real dc motor. keywords: nonlinear pid controller, dc motor, particle swarm optimization, neural networks, matlab, labview. 1. introduction direct current (dc) motors have been widely used in many industrial applications such as electric vehicles, steel rolling mills, electric cranes, fans, pumps, hoists, printing presses and robotic manipulators due to precise, wide, simple and continuous control characteristics based armature control method for the speed control [1]. many industrial applications use pid control to maintain constant process variable. the output of pid controllers (proportionalintegrative derivative controllers) is a linear combination of the input, the derivative of the input and the integral of the input therefore it is widely used and enjoys significant popularity, because of its simplicity, effectiveness and robustness [2]. however, pid controller is sensitive to plant parameter variations and the controller gains must be carefully selected for a desired response. in order to overcome these problems, many control techniques, include the adaptive control, variable structure control and robust control have been applied in dc motor speed [3]. several years ago, the neural networks are used in a speed control loop applied to a dc motor and the learning capability of neural networks implemented an auto-adaptive control structure to learn the dynamic behavior of the silicon-controlled rectifier (scr)-driven dc motor [4]. a novel improved pid algorithm based on recurrent wavelet neural network was proposed in [5], which combines the capability of artificial neural networks for learning the process and the capability of wavelet decomposition for identification and control of dynamic systems. in [6] a novel adaptive neuro-fuzzy controller was applied on transverse flux linear motor for controlling its speed where the proposed controller presented fuzzy logic controller (flc) with self tuning scaling factors based on artificial neural network structure. also, a direct nonlinear adaptive state regulator was derived based on dynamic neural networks mailto:ahmedsas2040@yahoo.com ahmed sabah al-araji al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 7282 (2014) 73 and it was applied to control the speed of a nonlinearized dc motor and the control algorithm was that it covers the situation where the magnetic flux continuously varies was presented in [7]. in addition to that, dc series motors were preferred for mechatronic applications requiring high torque/speed ratios. the design and implementation of an open loop dc motor speed control that was based on a micro-controller and insulated-gate_bipolar_transistor‎ (igbt) drive stage that can predict the dynamic behavior of systems consisting of mechanical and electronic modules was very desirable as explained in [8]. there is other technique for speed control of the dc motor, a new method of tuning proportional integral (pi) coefficients for a permanent magnet dc motor drives was explained in [9], where artificial neural network was used to identify the whole system using maximum overshoot and settling time. the fundamental essence of the motivation of this work is that the tuning of the nonlinear pid controller in the real time requires a great effort and needs more time; therefore, the nonlinear pid controller is first carried out using the matlab simulation package which is very time saving and gives close parameter approximation for application in the real time system based on labview package at the end. in this paper, experimental investigation is carried out for the appropriate tuning parameters of the nonlinear pid neural controller that controls the speed of a dc motor using two techniques: trial and error method and pso to obtain the best speed response achievable based on a matlab simulation package. these parameters are then applied in the designed real time nonlinear pid controller based on labview package and the results obtained are compared against those of the simulation. the remainder of this paper is organized as follows: section two, describes the mathematical model of the dc motor speed system. in section three, the proposed nonlinear pid neural controller approach and tuning algorithm are derived. the simulation results (matlab) of the proposed controller are presented in section four. hardware design and real time results based on labview package are presented in section five and the conclusions are drawn in section six. 2. permanent magnet dc motor model a permanent magnet dc motor model can be derived using the linear dynamic equations with a two mass model equivalent system [10]: mb a aaaa k dt di lirv  …(1) atmmm m m ikb dt dw j   …(2) where ra, la, kb, kt are the dc motor parameters. va, ia are the dc motor voltage and current respectively. ωm is motor speed. τm the motor torque. jm the motor inertia. bm the damping coefficient. by taking the laplace transformation of the equations (1 and 2). )()()()( skssilsirsv mbaaaaa  …(3) where )(sk mb is e.m.f. ))(()()( slrsisksv aaamba   …(4) )()()()( sikssbssj atmmmmm   …(5) )())(( sbsjs mmmm   …(6) the block diagram of the dc motor model is shown in fig. 1. fig. 1. block diagram of the dc motor model. tk 1)/( 1 sbj b mm m 1)/( 1 srl r aa a )(sva + bk )(swm )(sia )(sm ahmed sabah al-araji al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 7282 (2014) 74 the parameters of the permanent magnet dc motor implemented in the designed system are shown in table (1) [11]. table 1, parameters of the dc motor. real parameter of dc motor values armature resistance ra 0.56 armature inductance la 0.023h inertia constant j 0.083 nm/(rad/s 2 ) damping constant b 0.006 nm/(rad/s) torque constant kt 0.43 nm/a back emf constant kb 0.43 v/(rad/sec) speed 250 rpm or 26 rad/sec dc supply 12 volt armature current ia 0.4 a 3. control methodology based on optimization algorithms the feedback pid neural controller is very important because it is necessary to stabilize the tracking error of the dc motor speed when the speed of the dc motor is drifted from the desired speed. the proposed structure of the nonlinear pid neural controller can be given in the form of block diagram, as shown in fig. 2. the trial and error method and particle swarm optimization will generate the optimal parameters for the nonlinear pid neural controller in order to obtain best control signal that will minimize the tracking error of the dc motor speed. fig. 2. the proposed block diagram of nonlinear pid controller. the proposed nonlinear pid neural controller has the characteristics of control agility, strong adaptability, good dynamic characteristic and robustness because it is based on a conventional pid controller that consists of three terms: proportional, integral and derivative where the standard form of a pid controller is given in the sdomain as equation (7) [12]. sk s k kdipsgc d i p )( …(7) where kp, ki and kd are called the proportional gain, the integral gain and the derivative gain respectively. the proposed nonlinear pid neural controller scheme is based on the discrete-time pid as equation (8). )]([)]1()([)1()( kekikekekpkuku  )]2()1(2)([  kekekekd …(8) therefore, the tuning pid input vector consists of )(ke , )1( ke , )2( ke and )1( ku , where )(ke and )1( ku denote the input error signals and the pid output signal respectively. the nonlinear pid neural controller for speed of dc motor system can be shown in fig. 3. dc motor model nonlinear pid controller particle swarm optimization algorithm kp ki kd desired speed e(k) u(k) speed output + u(k-1) gain mapping ahmed sabah al-araji al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 7282 (2014) 75 fig. 3. the nonlinear pid neural feedback controller structure. the proposed control law of the feedback control signal ( u ) can be proposed as follows: oku 5)(  …(9) o is the output of the neural network that can be obtained from non-linear sigmoid activation function and multiple by scaling factor that is equal to 5. the nonlinear relationship of the sigmoid function can be presented in the following equation: 1 1 2    nete o …(10) net is calculated from this equation:  )()]1()([)( kkiekekekpknet )]2()1(2)([  kekekekd ...(11) the control parameters kikp, and kd of the nonlinear pid neural controller are adjusted using trial and error method and particle swarm optimization. 3.1. learning particle swarm optimization algorithm particle swarm optimization (pso) is a kind of algorithm to search for the best solution by simulating the movement and flocking of birds. pso algorithms use a population of individual (called particles) “flies” over the solution space in search for the optimal solution [13]. each particle has its own position and velocity to move around the search space. the particles are evaluated using a fitness function to see how close they are to the optimal solution [14]. the previous best value is called as pbest. thus, pbest is related only to a particular particle. it also has another value called gbest, which is the best value of all the particles pbest in the swarm. the nonlinear pid neural controller with nine weights parameters and the matrix is rewritten as an array to form a particle. particles are then initialized randomly and updated afterwards according to equations (12, 13, 14, 15, 16 and 17) in order to tune the pid parameters: )()()( 2211 1 k m kk m k m k m k m kpgbestrckppbestrckpkp   …(12) 11   k m k m k m kpkpkp …(13) )()()( 2211 1 k m kk m k m k m k m kigbestrckipbestrckiki   …(14) 11   k m k m k m kikiki …(15) )()()( 2211 1 k m kk m k m k m k m kdgbestrckdpbestrckdkd   …(16) 11   k m k m k m kdkdkd …(17) popm ,.....3,2,1 where pop is number of particles. k mk is the weight of particle m at k th iteration. c1 and c2 are the acceleration constants with positive values equal to 1.55. r1 and r2 are random numbers between 0 and 1. mpbest is best previous weight of m th particle. gbest is best particle among all the particle in the population.  is the inertia weight factor and it is equal to 0.75. mean square error (mse) function for dc motor speed system is chosen as criterion for estimating the model performance and an objective function to be minimized as equation (18): 2 1 ))()(( 1    n j jtspeedoutpujeddesiredspe n mse ...(18) o h kp ki kd )(ke )2( ke × )(ku )1( ku + + -2 +1 +1 +1 + +1 -1 )1( ke +1 scaling factor ahmed sabah al-araji al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 7282 (2014) 76 where n is the number of samples and equal to 1000. the number of dimension in particle swarm optimization is equal to three because the nonlinear pid has three parameters. the mean square error function is chosen as criterion for estimating the model performance as in equation (18). the steps of pso for nonlinear pid neural controller can be described as follows: step1 initial searching points 0kp , 0ki , 0kd , 0kp , 0ki and 0kd of each particle are usually generated randomly within the allowable range. note that the dimension of search space consists of all the parameters used in the nonlinear pid neural controller, as shown in fig. 2. the current searching point is set to pbest for each particle. the best-evaluated value of pbest is set to gbest and the particle number with the best value is stored. step2 the objective function value is calculated for each particle by using equation (18). if the value is better than the current pbest of the particle, the pbest value is replaced by the current value. if the best value of pbest is better than the current gbest, gbest is replaced by the best value and the particle number with the best value is stored. step3 the current searching point of each particle is updated using equations (12, 13, 14, 15, 16 and 17). step4 if the current iteration number reaches the predetermined maximum iteration number, then exit. otherwise, return to step 2. 4. simulation results this section discusses the mapping between the real process and the simulation carried out using matlab package. the proposed nonlinear pid neural controller in conjunction with the input voltage to the dc motor unit which has a linear relationship with saturation transfer function has a slope equal to (12/5). this slope is used as a mapping gain to limit the motor drive voltage to 12volts which is chosen in accordance with the dc motor modeling description. to investigate the open loop response of the dc motor system, the open loop step response of the speed of the dc motor is shown in fig. 4. when applying a step change in the input voltage of the motor equal to (0.438) volt, it will increase the motor speed by 1 rad/sec with reference to its speed at the initial condition which is equal to zero rad/sec. the settling time for the speed of the dc motor is equal to 1.2sec and the time constant is equal to 0.082sec. therefore the sampling interval for the dc motor speed control is chosen to be 0.01sec using shannon theory. fig. 4. step response of open loop dc motor system. the proposed nonlinear pid neural controller scheme as in fig. 2, is applied to the dc motor model and it used two algorithms for tuning the parameters of the controller; first algorithm is trial and error method where executing many trial runs to find the well system response by varying the parameters of the pid controller and it has taken a long time to produce the achievable system response. but the second algorithm is pso and applying the steps of the proposed learning algorithm for tuning pid controller's parameters to find the best system response at only one run where the pso algorithm is set to the following parameters: population of particle is equal to 25. number of iteration is equal to 100. number of weight in each particle is equal to 3 because there are three parameters of pid controller. the nonlinear pid neural controller parameters that are obtained from the simulation package that give the best system responses are shown in table (2). table 2, pid controller parameters. tuning algorithm kp ki kd trial and error 35 2.1 3.2 pso 42.8047 1.6147 0.9996 0 0.2 0.4 0.6 0.8 1 1.2 1.4 0 0.2 0.4 0.6 0.8 1 1.2 samples (sec) s p e e d o f d c m o to r ( r a d /s e c ) ahmed sabah al-araji al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 7282 (2014) 77 from the simulation results, the closed loop time response of the dc motor speed control system with nonlinear pid neural controller based on pso algorithm is illustrated in figs. 5a, 5b and 5c for the initial speed of zero rad/sec. fig. 5a. the speed output of the dc motor. 0 1 2 3 4 5 6 7 8 9 10 0 2 4 6 8 10 12 samples (sec) c o n tr o l a c ti o n ( v o lt ) fig. 5b. the control action. figure 5a shows the response of the dc motor speed output to a steps change, it had small over shoot at first step (2.82) rad/sec and no over shoots in the other steps as well as the steady-state error is equal to zero in each steps when the desired change in speed is (25, 75, 125, 75 and 25) r.p.m as (2.84, 8.52, 14.2, 8.52 and 2.84) rad/sec respectively. the nonlinear pid neural control action response is shown in fig. 5b that it had few spikes in response to the desired step change in motor speed with very small oscillation in order to keep the speed output of the dc motor within desired range. the error between the desired speed and the actual speed output of the dc motor is shown in fig. 5c and it is very small in the transient and becomes very close to zero in steady state. 0 1 2 3 4 5 6 7 8 9 10 -6 -4 -2 0 2 4 6 samples (sec) s p e e d e r r o r ( r a d /s e c ) fig. 5c. the speed error. the fundamental essence for applying the proposed control algorithm based on pso is to minimize the tracking speed error and to obtain smoothness of the control signal in comparison with trial and error method in terms of time saving and obtaining an optimal control parameters of the nonlinear pid neural controller with best speed response. 5. hardware design and real time results in this section, the experimental setup for the real-time speed control of the dc motor is shown in fig. 6. the setup consists of:  the permanent magnet dc motor and dc tacho generator with a sensitivity figure equal to 20mv/rad/sec. the motor has a speed range of operation "0 rad/sec to 26 rad/sec".  dc power supply that provides power to the motor and the rest of the circuitry.  the data acquisition device from national instrument ni company.  motor drive board based on lm324 operational amplifiers. 0 1 2 3 4 5 6 7 8 9 10 0 2 4 6 8 10 12 14 samples (sec) s p e e d o f d c m o to r ( r a d /s e c ) actual speed output desired speed ahmed sabah al-araji al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 7282 (2014) 78 fig. 6. the experimental work in the real-time speed control. in the real time computer control system based on labview package, the fine tuned parameters of the nonlinear pid neural controller that have been obtained from the simulation based on pso algorithm are applied in the real time computer controller with sampling time equal to 0.01sec. the computer code and front panel diagram of the control algorithm have been written in the labview, as shown in fig. 7. fig. 7. labview control algorithm (a) front panel diagram; (b) computer code program. power supply driver motor dc motor ni-daqmx-usb 6009 device electronic circuit digital avo meter tacho gen. front panel diagram of labview package data usb cable a b ahmed sabah al-araji al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 7282 (2014) 79 figure 8 shows the electronic circuit diagram design for the speed control system and it consists of multi-stage as follows: the first stage is signal conditioning circuit that includes a voltage follower with unity gain to avoid the attenuation in the feedback signal of the tacho generator and the first order low pass filter stage that has a cutoff frequency of 10hz which will remove noise components possible to occur in the sensor outputs especially within mains supply frequency at 50hz. this filter removes noise components within mains frequency effectively from the tacho generator output prior to delivering it to the level conditioning amplifier with unity gain. this amplifier is built using lm324 quad operational amplifier [15]. the output of this amplifier is fed to the analog to digital converter adc 14 bit high speed low power successive approximation converter of the ni-daqmx-usb 6009 device with range of input voltage from 0 to 5 volt as second stage. inside the personal computer, labview software instructions compares the sensed speed signal received via this interface with the set point desired speed. the resulting error is given as an input to the nonlinear pid neural controller that has been built in the labview package. the nonlinear pid neural controller attempts to reduce the error to zero by changing the control action “input voltage to the dc motor” which is in the form of real data varying within "0 to 5". these data are sent to the motor drive electronics through the usb connector to digital to analog converter dac 12 bit of the ni-daqmx-usb 6009 device with range of output voltage from 0 to 5 volt as third stage. the output of this dac is sent to an op-amp based amplifier that has a gain of "2.4" as fourth stage. this amplifier is also built using lm324 operational amplifier. to remove the nonlinear effect “dead zone” in the modeling of the dc motor system, a small dc drive voltage is added to the motor in order to minimize its effect as shown in the motor drive electronic circuit design in the fifth stage. the output of this amplifier is fed to the motor drive stage to furnish the final output required to drive the dc motor as sixth stage. the motor accepts drive voltages ranging from "0v to 12v" which will drive the motor through the speed range of "0 rad/sec to 26 rad/sec". the speed response of the dc motor in real time is shown in fig.9a. it can be seen that it is a fast response with oscillation output value in the range of ( sec))/(02.0 rad . the response of the feedback nonlinear pid neural control action is shown in fig. 9b. it has many spikes during the step change in the desired speed and a small oscillation can also be observed. this action of the controller has kept the speed of the dc motor within the desired value with minimum tracking speed error. the tracking error between the desired speed and the actual speed output of the dc motor which was very small in the transient state and had steady state value equal to sec))/(02.0 rad , is shown in fig. 9c. in fact, there are small differences in results between the real time control action and the simulation control action because in the real time there were accumulation errors such as undesirable characteristics of speed sensor (tacho generator) "non-linearity, drift, and offset", offset u1a lm324ad 3 2 11 4 1 u1c lm324ad 10 9 11 4 8r1 1.59kω r174.1kω c1 10µf u1d lm324ad 12 13 11 4 14 vcc 12v r10 4kω dz 5volt c3 10µf 10kω key=a 50% r3 10kω r44.1kω r5 10kω r6 100kωu2a lm324ad 3 2 11 4 1 r7 100kω r9 100kω r8 100kω r11 50kω u2b lm324ad 5 6 11 4 7 bus1bus1 bus1 bus2 bus3 ni-daqmxusb 6009 device signal from tacho-generator signal to dc motor driver cct fig. 8. the schematic diagram of the electronic control circuit. analog input analog output ahmed sabah al-araji al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 7282 (2014) 80 in the operational amplifier output, and the quantization error of the analog to digital and digital to analogue converters; therefore, the results in the real time have small oscillation in the actual speed output of the dc motor as it is equal to sec))/(02.0 rad . . fig. 9. (a) actual speed of dc motor; (b) actual control action; (c) speed error of dc motor. a b c ahmed sabah al-araji al-khwarizmi engineering journal, vol. 10, no. 1, p.p. 7282 (2014) 81 6. conclusions nonlinear pid neural speed control methodology for the permanent magnet dc motor model has been presented in this paper. it has been designed and tested using matlab package and carried out on real dc motor using labview package. simulation results and real time computer control results show evidently that the proposed nonlinear pid neural controller model has demonstrated the capability of tracking desired speed and effective minimization of the tracking speed errors of the real dc motor model as well as it has the capability of generating smooth and suitable voltage control action 7. references [1] b. omar, a. haikal and f. areed, design adaptive neuro-fuzzy speed controller for an electro-mechanical system. ain shams engineering journal. vol. 2, (2011), pp. 99107. [2] t. hagglund, k. astrom, automatic tuning of pid controllers. in w.s. levine (ed), the control handbook, crc press, boca raton, fl, 1996, pp. 817-826. [3] d. kukolj, s. kuzmanovic and e. levi, design of a pid-like compound fuzzy logic controller. engineering applications of artificial intelligence. vol. 14, (2001), pp. 785-803. [4] l. eduardo and g. torres, simulation of a neural net controller for motor drives. mathematics and computers in simulation. vol. 38, (1995), pp. 311-322. [5] m. li and d. liu, a novel adaptive selftuned pid controller based on recurrentwavelet-neural-network for pmsm speed servo drive system. procedia engineering. vol. 15, (2011), pp. 282-287. [6] h. hasanien, s. muyeen and j. tamura, speed control of permanent magnet excitation transverse flux linear motor by using adaptive neuro-fuzzy controller. energy conversion and management. vol. 51, (2010), pp. 2762-2768. [7] t. kara and i. lyas, nonlinear modeling and identification of a dc motor for bidirectional operation with real time experiments. energy conversion and management. vol. 45, (2004), pp. 10871106. [8] p. strwart, d. glagwin, j. stewart and r. cowley, generator voltage stabilization for series-hybrid electric vehicles. the instrumentation, systems and automation society. vol. 47, (2008), pp. 222-228. [9] m. demirtas, off-line tuning of a pi speed controller for a permanent magnet brushless dc motor using dsp. energy conversion and management. vol. 52, (2011), pp. 264273. [10] k. ogata. modern control engineering. 4th edition, by addisonwesley publishing company, inc. 2003. [11] internet website www.feedbackinstruments.com/dcmotordatasheet. text manual. accessed sept. 2013. [12] q. zhong, robust control of time-delay systems. springer–verlag london limited 2006 [13] c. zhang, m. wu and l. luan, an optimal pso distributed precoding algorithm in qrd-based multi-relay system. future generation computer systems. vol. 29, (2013), pp. 107-113. [14] h. di, s. ali and d. yun-feng, an improved particle swarm optimization for parametric optimization of flexible satellite controller. applied mathmetics and computation. vol. 217, (2011), pp. 8512-8521. [15] s. faulkenberry, introduction to operational amplifiers with linear circuit applications. john-wiley inc. 1986. http://www.feedback-instruments.com/dcmotordatasheet http://www.feedback-instruments.com/dcmotordatasheet (2014) 7282، صفحة 1، العدد10دمجلة الخوارزمي الهندسية المجل احمد صباح االعرجي 82 مر تصميم مسيطر عصبي تناسبي تكاملي تفاضلي الخطي للسيطرة على سرعة محرك تيار مست ثابت المغناطيسية مبنيا على أساس الخوارزمية األمثلية أحمد صباح االعرجي الجامعة التكنولوجية /قسم هندسة السيطرة والنظم ahmedsas2040@yahoo.com: البريد االلكتروني الخالصة تم . المحرك التيار المستمر بشكل تجريبي باستخدام المسيطر العصبي التناسبي التكاملي التفاضلي الالخطيفي هذا البحث تمت السيطرة على سرعة الالخطي إليجاد استخدام طريقة التجربة والخطأ وتقنية حشد الجسيمات األمثلية لسهولة وسرعة تنغيم عناصر المسيطر العصبي التناسبي التكاملي التفاضلي .ة المحرك التيار المستمرأفضل استجابة لسرع لتنفيذ خوارزمية التنغيم لعناصر المسيطر الالخطي وبعد ذلك تم استخدام هذه ( matlab)تم استخدام الحقيبة البرمجية , لتوفير الزمن في النظام الحقيقي (. labview)العناصر في تصميم المسيطر الالخطي للنظام في الزمن الحقيقي باستخدام الحقيبة البرمجية لسرعة المحرك التيار رح من حيث سرعة ونعومة االستجابةمع النتائج التجريبية وتبين كفاءة تأثير الخوارزمية المسيطر المقت لقد تم مقارنة نتائج المحاكاة . المستمر الحقيقي mailto:ahmedsas2040@yahoo.com 107-122عمر و مريم al-khwarizmi engineering journal,vol. 13, no. 1, p.p. model reference adaptive control based on a self neural network utilizing micro artificial immune systems omar farouq lutfy *,**department of control and systems engineering *email: **email: (received 18 september https://doi.org/10.22153/kej.2017.01.006 abstract this paper presents an intelligent model reference adaptive control (mrac) utilizing a self network (srwnn) to control nonlinear systems. the proposed srwnn is an improved reported wavelet neural network (wnn). in particular, this improvement was achieved by adopting two modifications to the original wnn structure. these modifications include, firstly, the utilization of a specific initialization phas improve the convergence to the optimal weight values, and secondly, the inclusion of self wavelons of the wavelet layer. furthermore, an on performance of the srwnn-based mrac. as the training method, the recently developed modified micro artificial immune system (mmais) was used to optimize the parameters of the srwnn. the effectiveness of this control approach was demonstrated by controlling several nonlinear dynamica evaluation tests were conducted, including control performance tests, robustness tests, and generalization tests. from these tests, the srwnn-based mrac has exhibited its effectiveness and generalization ability. in addition, a comparative study was made with other related controllers, namely the original wnn, the artificial neural network (ann), and the modified recurrent network (mrn). the results of these com tests indicated the superiority of the srwnn controller over the other related controllers. keywords: artificial neural network, micro artificial immune system wavelet neural network , wavelet neural networ 1. introduction adaptive control techniques have gained widespread popularity among researchers due to their ability in handling different types of complex and nonlinear control problems. model reference adaptive control (mrac) is a major type of adaptive control strategies. owing to its ability to guarantee the global asymptotic stability, the mrac scheme has been successfully employed to control different linear systems [1-5]. however, it is well-known that most real systems are inherently nonlinear in nature, and hence, impractical to describe such systems by linear mathematical models. this fact limits the 1 khwarizmi engineering journal,vol. 13, no. 1, p.p. 107122 (2017) model reference adaptive control based on a self-recurrent wavelet neural network utilizing micro artificial immune systems omar farouq lutfy* maryam hassan dawood** *department of control and systems engineering/ university of technology *email: 60157@uotechnology.edu.iq **email: mariam.hassan93@yahoo.com september 2016; accepted 4 january 2017) https://doi.org/10.22153/kej.2017.01.006 this paper presents an intelligent model reference adaptive control (mrac) utilizing a self-recurrent wavelet neural network (srwnn) to control nonlinear systems. the proposed srwnn is an improved version of a previously reported wavelet neural network (wnn). in particular, this improvement was achieved by adopting two modifications to the original wnn structure. these modifications include, firstly, the utilization of a specific initialization phas improve the convergence to the optimal weight values, and secondly, the inclusion of self-feedback weights to the wavelons of the wavelet layer. furthermore, an on-line training procedure was proposed to enhance the control sed mrac. as the training method, the recently developed modified micro artificial used to optimize the parameters of the srwnn. the effectiveness of this control demonstrated by controlling several nonlinear dynamical systems. for each of these systems, several evaluation tests were conducted, including control performance tests, robustness tests, and generalization tests. from based mrac has exhibited its effectiveness regarding accurate control, disturbance rejection, and generalization ability. in addition, a comparative study was made with other related controllers, namely the original wnn, the artificial neural network (ann), and the modified recurrent network (mrn). the results of these com tests indicated the superiority of the srwnn controller over the other related controllers. micro artificial immune system, model reference adaptive control al network. adaptive control techniques have gained widespread popularity among researchers due to their ability in handling different types of complex and nonlinear control problems. model reference adaptive control (mrac) is a major type of es. owing to its ability to guarantee the global asymptotic stability, the mrac scheme has been successfully employed 5]. however, known that most real systems are inherently nonlinear in nature, and hence, it is impractical to describe such systems by linear mathematical models. this fact limits the effectiveness of utilizing the conventional mrac scheme to control such nonlinear systems. in order to mitigate this difficulty, many researchers have utilized the nonlinear function approximation capability of artificial neural network (ann) to form a nonlinear ann mrac scheme to control nonlinear systems [6 10]. despite this widespread utilization of ann, recently a more powerful neural network structure, namely the wavelet neural network (wnn), has received extensive attention in the literature, especially in handling various control problems [11-14]. the strength of wnn approximation capability is realized by combining the theory of wavelets and the ann al-khwarizmi engineering journal ent wavelet neural network utilizing micro artificial immune systems recurrent wavelet neural version of a previously reported wavelet neural network (wnn). in particular, this improvement was achieved by adopting two modifications to the original wnn structure. these modifications include, firstly, the utilization of a specific initialization phase to feedback weights to the proposed to enhance the control sed mrac. as the training method, the recently developed modified micro artificial used to optimize the parameters of the srwnn. the effectiveness of this control l systems. for each of these systems, several evaluation tests were conducted, including control performance tests, robustness tests, and generalization tests. from l, disturbance rejection, and generalization ability. in addition, a comparative study was made with other related controllers, namely the original wnn, the artificial neural network (ann), and the modified recurrent network (mrn). the results of these comparison model reference adaptive control, self-recurrent effectiveness of utilizing the conventional mrac scheme to control such nonlinear systems. in order to mitigate this difficulty, many researchers the nonlinear function approximation capability of artificial neural network (ann) to form a nonlinear ann-based mrac scheme to control nonlinear systems [610]. despite this widespread utilization of ann, recently a more powerful neural network namely the wavelet neural network (wnn), has received extensive attention in the literature, especially in handling various control 14]. the strength of wnn approximation capability is realized by combining the theory of wavelets and the ann into a unified pdf created with pdffactory trial version www.pdffactory.com https://doi.org/10.22153/kej.2017.01.006 mailto:60157@uotechnology.edu.iq mailto:mariam.hassan93@yahoo.com https://doi.org/10.22153/kej.2017.01.006 http://www.pdffactory.com http://www.pdffactory.com omar farouq lutfy al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 107122 (2017) 108 framework. hence, wnns possess both the localization property of wavelet transform together with the learning and generalization abilities of anns. in spite of these desirable properties of wnns, only few efforts have been made to employ wnns in mrac schemes. for instance, wai and chang [15] employed a wnnbased mrac scheme to control an induction motor drive. in addition, the authors used the back stepping approach to design another feedback control action to get the required performance. in this method, to optimize the above structure, several learning rates had to be chosen according to the controlled system. therefore, the above method is characterized by its difficulty in implementation due to the involvement of two complex control methods. as another mrac system, yoo et al. [16] used two srwnns, one of which acts as an identifier and the other as a controller, in a mrac structure to control nonlinear systems. both of these srwnns were trained by a gradient descent (gd) method to achieve the desired response. however, in addition to the complexity of this control approach, gd techniques are characterized by their slow convergence rates and the inclination to get stuck at local minima in the search space [3]. in order to avoid these limitations in gd methods, more attention has been given to evolutionary algorithms, due to their ability in finding the global optimal solution of a particular problem. in this regard, genetic algorithms (gas) are regarded as the most essential types of evolutionary algorithms [17, 18]. however, in recent years, a more powerful evolutionary algorithm has received considerable attention among researchers. this relatively new algorithm is the artificial immune system (ais), which was built based on some concepts from the natural immune system. compared to the ga, the ais algorithm has a more efficient mutation operator which results in a better diversity of populations [19, 20]. in this regard, utilizing this promising optimization method, lutfy [21] proposed to use a modified micro artificial immune system (mmais) to train a wnn as the main controller in the mrac scheme. however, in the above work, the wnn controller was treated as a black box approximator without using an initializing phase, which can affect the wnn approximation capability. in this context, it is worth noticing that the wavelet is a rapidly vanishing function which is fully defined by dilation and translation factors [22]. consequently, suitable initialization of these factors plays an important role in improving the wnn approximation capability. however, despite this importance for the initialization process, several researchers did not consider a specific initialization approach for these parameters [11, 13, 16, 21, 23].to this end, aiming at enhancing the performance of the wnn controller, the motivation of the present work was to propose a more efficient version of the wnn structure. this modified wnn structure encompasses two amendments, namely; adopting an initialization phase to enhance the convergence to the optimal weights and including self-feedback connections to the wavelons in the wavelet layer. these modifications have contributed in improving the approximation capability of the proposed controller compared to other related controllers, as will be seen in the simulation results of the present work. moreover, an on-line mmaisbased adaptive control design is used to further enhance the performance of the srwnn controller. to the best of the authors' knowledge, this is the first utilization of the mmais in an online adaptive control design. the remaining content of this paper is arranged as follows: section 2 discusses the utilization of the srwnn controller within the mrac. the srwnn structure is elucidated in section 3. basic concepts of the ais and the mmais algorithms are given in section 4. to demonstrate the efficiency of the proposed srwnn-based mrac, several performance tests along with two comparative studies are presented in section 5. finally, the main conclusions are drawn in section 6. 2. the srwnn-based mrac structure the main idea behind the mrac is to specify the desired behavior of the controlled system by a reference model. this reference model is simply a plant of known dynamical structure whose task is to provide the desired output by applying a given input signal. then, by applying a suitable optimization method, the main goal of mrac design is to regulate the controller parameters by minimizing the difference between the outputs of the reference model and the controlled system [24]. utilizing this basic mrac design approach, the srwnn structure is employed in this work as the main controller to constitute a nonlinear mrac scheme. figure 1 depicts a block diagram of the proposed srwnn-based mrac scheme. pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com omar farouq lutfy al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 107122 (2017) 109 fig. 1 structure of the srwnnbased mrac system. in particular, the design of the srwnn controller in the framework of mrac is based on the generalized inverse control technique. in other words, the srwnn is trained to work as an inverse controller, as illustrated in fig. 1. in order to clarify this design approach, consider the following nonlinear autoregressive moving average (narma) model, which is utilized to describe single-input single output (siso) discrete-time nonlinear systems [9, 21, 24]: (� + 1) = ���(�), �(� − 1), … , �(� − �+ 1), �(�), … , �(� − �+ 1)� … (1) where �(�) and �(�) are the system output and input, respectively, �(. )is a smooth nonlinear function, n and m are the system orders, and k represents the discrete-time instant. subsequently, in order to deduce the control law, it is assumed that equation (1) above is invertible resulting in the following equation: (�) = ℎ���(� + 1), �(�), �(� − 1), … , �(� −� + 1), �(� − 1), … , �(� − � + 1)� …(2) where,��(� + 1) represents the output of the reference model at time instant (k + 1) and ℎ(. )is the inverse function of f in equation (1), such that:ℎ(. ) = ���(. ). in order to realize the control law given in equation (2), a suitable function approximator must be used to approximate the inverse function ℎ(. ). in particular, due to its remarkable nonlinear function approximation capability, the srwnn is employed in this work to achieve this task. as can be seen from fig. 1, the training of the srwnn structure is accomplished by minimizing the error signal between the outputs of the actual system and the reference model. more precisely, this error signal is described by the following formula [22]: � = 12 �(�(� + 1) − ��� ��� (k + 1))� , … (3) where n represents the number of samples. in particular, this error signal is utilized as the performance index to be minimized viaan appropriate optimization method. in the present work, the mmais algorithm is employed for this task, as illustrated in fig. 1. 3. the srwnn structure as mentioned before, the proposed srwnn structure, which is shown in fig. 2, is an improved version of the previously reported wnn structure [21]. fig. 2. structure of the srwnn controller. as depicted in fig. 2, the srwnn is a multiinput single-output network which has an input layer, a mother wavelet (wavelon) layer, and an output layer. these layers work together to generate the final output of the srwnn structure. in the following, the functions of these layers are discussed in detail [16, 21]: layer 1: the function of this layer, which is called the input layer, is to convey the input variables as they are to the next layer. as explained in section 2, the utilization of the srwnn as the controller in the mrac requires the selection of the input variables to be of the form: [��(� + 1), �(�), … , �(� − � + 1), �(� − 1), … , �(� − � + 1)] … (4) therefore, the number of nodes in this layer depends on the orders of the controlled system. ym(k+1) y(k), …, y(k-n+1) u(k-1), …, u(k-m+1) ym(k+1) u(k) r(k) y(k+1) e(k+1) reference model srwnn controller nonlinear plant mmais algorithm 1 x1 x2 xni vji b c1 cnw a1 a2 ani input layer wavelon layer output layer θ1 θ2 θ3 θnw ψ1 ψnw ψ2 ψ3 ∑ z-1 z-1 z-1 z-1 pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com omar farouq lutfy al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 107122 (2017) 110 layer 2: this layer is referred to as the mother wavelet or the wavelon layer. each node (wavelon) in this layer possesses a mother wavelet and a self-feedback connection with an adjustable parameter. as the mother wavelet, the mexican hat function is employed in this work, and this function has the following form: (�) = (1 − ��)�� 2 2 1 x … (5) to compute the wavelon outputs, the wavelet y �of each node is obtained from its mother wavelet function �according to the following expression: ��(�) = �����, ���ℎ �� = �� �� ����� + ��(� − 1). ���� ��� � �� … (6) where dj and tj demarcate dilation and translation factors of the srwnn, respectively, ni is the number of input nodes, xi denotes the ith input variable, vji is the link connection from node i in the input layer to wavelon j in the mother wavelet layer, )1( -kjy represents the memory term, whose task is to store the previous state of the jth wavelon, and jq is the link value of the selffeedback connection belonging to the jth wavelon. specifically, this weight value is responsible for deciding the rate of information storage. finally, the jth wavelon's output is calculated by making use of the mexican hat function as expressed in the following: ���� = �1 − ������� �− 12 ���� … (7) it is worth to highlight that as an advantage of the srwnn over the wnn, the self-feedback connections in the wavelon layer have the ability to reserve the previous network information. in other words, the current network state contributes in producing the network output for the next sample of time. this feature enhances the overall approximation ability of the srwnn compared to the conventional wnn, as will be demonstrated in the simulation results of this work. layer 3: this layer, known as the output layer, has only one node. the task of this node is to generate the srwnn output, using the following equation: � = � ����(�) + � ���� ��� �� ��� �� + � … (8) where, as can be observed from fig. 2, nw and ni denote the number of nodes in the wavelon layer and the input layer, respectively, cj is the weight connecting wavelon j and the output node, a i is the weight connecting node i in the input layer and the output node, and b represents a bias connection to the output node. since the srwnn structure described above is utilized as a controller in this work, the srwnn output in equation (8), y, represents the control action applied to the controlled system at a given sample of time. 3.1. initialization of the srwnn parameters in conventional ann, the network parameters are randomly initialized to small values and the whole network functions as a black box approximator. this initialization process may lead to getting stuck at local minima and decrease the network convergence rate [25]. however, unlike anns, the wnn structure consists of dilation and translation factors which affect the shape of the wavelet. more precisely, a wavelet is a waveform defined by suitable dilation and translation parameters which determine the waveform effectiveness during only a limited duration. therefore, a random initialization for dilation and translation parameters may generate ineffective wavelons which negatively affect the network convergence rate. for example, a very small value for the dilation factor may result in a wavelet with too local property that makes it inappropriate for the training data under consideration. on the other hand, if the translation factor is not initialized properly, the wavelet may materialize outside the domain of the training samples. nevertheless, despite this influence for dilation and translation factors, several researchers did not consider a specific initialization process for these parameters [11, 13, 16, 21, 23]. in this work, in order to handle this issue, dilation and translation factors are initialized according to the available information from the dataset according to the following procedure [22, 25]. let the variables a and b be the minimum and the maximum values that the input variables can take, respectively. then, the translation and the dilation factors are initialized as follows: �� = 12 (� + �) … (9) and �� = 0.2(� − �) … (10) pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com omar farouq lutfy al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 107122 (2017) 111 where tj and dj are translation and dilation factors of wavelon j in the wavelet layer and j = 1, 2, …, nw. as stated before, this initialization process takes into account the input domain defined by the training samples, and hence, it ensures the coverage of the whole input domain by the initial wavelets. on the other hand, initial value selection for the remaining srwnn parameters is less crucial; therefore, they are initialized to small random values. as can be noticed, the above initialization procedure is very simple, yet it has considerably improved the approximation capability of the srwnn. 3.2. training of the srwnn in the framework of mrac, training of the srwnn controller dictates finding the optimal values for the srwnn parameters by minimizing the error between the outputs of the reference model and the controlled system. as discussed in section 3, the srwnn consists of different adjustable parameters, which can be summarized by the following set s = [cj dj tj vji a i b ��], … (11) where the adjustable parameters in the above equation were defined in section 3. these parameters are optimized by the mmais algorithm in this work, as discussed in the following section. 4. artificial immune system the underlying principle behind artificial immune system (ais) is based on the information processing capability of the biological immune system which is a parallel, highly evolved, and distributed adaptive system. as a result, the ais algorithm possesses powerful exploration and exploitation operators. in particular, compared to other evolutionary techniques, the ais algorithm has more efficient mutation operators, and moreover, it can achieve better diversity of populations which leads to faster convergence rates [19, 20]. in order to understand the basic operators of the ais algorithm and relate them to their biological counterparts, the main functions of the biological immune system are discussed below. 4.1. biological immune system the biological immune system is a powerful defense network whose responsibility is to detect the incursion of foreign antigens and destroy them to protect the human body from these diseasecausing substances. for this purpose, the biological immune system employs an enormous variety of antibodies, which are produced by the b cells, to counteract the effect of these harmful antigens [26]. more specifically, each antibody type has the ability to identify a specific antigen type using a correlation measure between the antibody and the antigen. this correlation measure is called the affinity value [27]. based on this affinity value, once an external antigen is recognized, the b cells with high affinity to that antigen will explosively generate antibodies (cloned cells) to fight the antigen in a process known as the cloning operator. moreover, these cloned cells undergo certain somatic hypermutation to make sure that the cloned cells will differ from their parent cell to adapt the immune system against other possible variations of the stimulating antigen [20]. to globally enhance the population of cells, the cells that are seldom stimulated by the attacking antigen are removed and replaced by other recruited cells. then, after eliminating the antigen, mature b cells are repressed gradually to certain regular level except some cells which become memory cells. these memory b cells facilitate the immune system response when the same or similar antigen attacks again, since all the information on the attacking antigen are already stored in the memory cells [26, 28, 29]. 4.2. micro-ais utilizing certain concepts from the biological immune system described above, several variations of the ais algorithm have been effectively employed to solve various optimization problems [27, 30, 31]. however, the cloning operator in the traditional ais algorithm has a drawback represented by the increase in the population size which entails a long execution time and substantial memory exploitation. to alleviate this problem, the authors in [32] suggested another version of the ais algorithm, which was called the micro-ais algorithm, based on utilizing a reduced population size. the assumption behind the micro-ais was that decreasing the antibody number in a population results in a decrease in the number of cost function evaluations, which consequently increases the convergence speed and reduces the memory usage. however, in the original microais algorithm, the mutation operator did not offer the necessary variable variations for solving a pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com omar farouq lutfy al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 107122 (2017) 112 particular problem. thus, to enhance the searching capability of the original method, a mmais algorithm was presented in [21] by improving the mutation operator of the original method. due to its effectiveness in several applications [21, 33, 34], the mmais algorithm is exploited in this work to optimize the parameters of the proposed srwnn controller based on the mrac strategy, as will be elucidated in the following section. 4.3. procedure of applying the mmais algorithm to train the srwnn controller the following procedure illustrates the application of the mmais algorithm to train the srwnn controller in the framework of mrac strategy. step 1: initialize the maximum number of iterations and the probability of mutation, pm. step 2: produce a starting (initial) population. this population consists of five antibodies which are randomly generated within preselected ranges. each of these antibodies represents a single srwnn controller which is defined by the adjustable parameters given in equation (11). these five antibodies enter a nominal convergence loop, with 10 iterations, as described below. step 3: set the counter of the nominal convergence loop to 1, and do the following: step 3-1: for each antibody in the current population, compute the objective function using the performance index defined in equation (3). next, for each antibody, find the affinity value according to the following equation: ������� = 1��������� �������� + � … (12) where ε is a small constant which is used to evade the division by zero. step 3-2: sort descending the antibodies based on their affinity values. as a result, the antibody with the largest affinity value, which is called bestab, becomes the first one. step 3-3: generate a specific number of clones from the current five antibodies utilizing the following expression: �� = ��� − (� − 1)�� ��� … (13) where ��the number of clones to be produced, n isis the number of antibodies in the current population, and i is the antibody index. thus, by using equation (13), a five-antibody population produces a 15-clone population. in particular, bestab produces five clones; the second antibody produces four clones; and so on until the fifth antibody is encountered which produces one clone. step 3-4: perform the maturation of clones using the mutation operator. first, determine the mutation probability of each group of clones generated from a given antibody. this probability is computed according to the antibody affinity value and then it is uniformly reduced with iterations. therefore, the clones related to bestab are mutated less than other groups of clones. more specifically, the mutation probability is determined according to the following equation: �����������(�) = ���(�)∑ ���(�)���� … (14) wherei is the antibody index and n is the number of antibodies in the old population. moreover, to reduce the mutation probability within the nominal convergence loop, the following expression is utilized: �� �� ≥ ���� _��������(�)��������� … (15) , �ℎ�� ����� �ℎ� �������� �������� where iteration in the above equation is the current nominal convergence loop iteration. next, perform the mutation operator using the following expression: (����. ����)(���������. �����_��) … (16) where x' and x are the mutated decision variable and the decision variable to be mutated, respectively, rand is a random number generated within the range [0, 1], iteration is the current nominal convergence loop iteration, and group_nc represents the number of clones for each antibody group. regarding the five bestab clones, the variable range in equation (16) represents a random number generated between lower and upper bounds of the decision variables. for the remaining clones, other than the first five clones, range is the equivalent decision variable from bestab and the mutation operator is performed using equation (16). step 3-5: for each clone in the new population, calculate the objective function and the affinity value using equations (3) and (12), respectively. step 3-6: sort the 15 clones of the new population based on their affinity values in a descending order. step 3-7: from the sorted 15 clones, constitute a new population of five clones. in particular, as an elitism strategy, the first two clones are copied pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com omar farouq lutfy al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 107122 (2017) 113 into the new population. the other three clones are chosen randomly from the population of the 15 clones. step 3-8: if the counter of the nominal convergence loop has reached to its maximum limit, go to step 4. if not, set counter = conter + 1 and go back to step 3-1. step 4: after completing the nominal convergence loop, a new population of five antibodies is constituted by selecting the best two antibodies along with three other randomly generated ones. this new population enters the nominal convergence loop, specifically, step 3 above. the whole algorithm, including steps 3 and 4, continues until the stopping criterion is satisfied. particularly, the stopping criterion in the present work is defined by reaching the maximum iteration number. as an off-line design approach, the objective of the above training procedure is to optimize the srwnn parameters defined in equation (11). however, to realize adaptive control, the best controller found by the off-line design approach is further tuned by the mmais algorithm using the on-line training procedure described below. 4.4. on-line training procedure in the on-line design stage, the mmais algorithm starts with an initial population of five antibodies which include the best controller found from the off-line design stage along with other related controllers. as the on-line adapted parameters, only the weights between the wavelon and the output layers are allowed to be adjusted by the optimization algorithm. at each time step, the mmais algorithm selects the best controller, from a set of several candidate controllers, to control the plant. the general idea of the proposed on-line design approach was adopted from [35]. the following procedure illustrates the on-line training steps used in this work. af�inity = 1 │j│ … (18) step 1: as the starting population in the online design stage, constitute an initial population of five antibodies in which the first two antibodies represent the exact copies of the off-line designed controller. the remaining three antibodies are initialized by randomly generating the weights between the wavelon and the output layers. in this way, the best controller obtained from the off-line design stage is effectively utilized to provide useful information for the adaptive design stage. step 2: set the simulation time, k, to zero. step 3: collect the current reference input, r(k), the current system output, y(k), and the current reference model output, ym(k). step 4: calculate the next reference model output, ym(k+1), using the desired reference model equation. step 5: for each antibody in the current population, which consists of five antibodies, calculate the objective function using the following performance index: � = �(� + 1) − ��(� + 1) … (17) where y(k+1) is the system output at sample (k+1). after that, the affinity value of each antibody is found according to the following equation: ������� = 1│�│ … (18) step 6: the antibody with the largest affinity value is chosen as the controller for the current sampling time. however, due to the random operators in the mmais algorithm, the selected controller might not be the best solution for the current sampling time. to alleviate this difficulty, the error produced by the on-line designed controller is compared with that of the off-line designed one at a given sampling time. based on this error, which is defined by equation (17), if the on-line designed controller achieves less error value, it is used to control the plant at the next sampling time. otherwise, the off-line designed controller is selected as the controller for the next sampling time. from several simulation tests, this strategy has resulted in the best on-line controller performance as will be seen from the simulation results of the next section. step 7: produce the next population of the mmais algorithm using the procedure described in section 4.3, in particular steps 3-1 to 3-8. however, instead of equations (3) and (12), equations (17) and (18) are used to evaluate the performance of each antibody. after completing the nominal convergence loop, a new population of five antibodies is generated. step 8: if the simulation time, k, has reached to its maximum value, the algorithm is terminated. otherwise, set k = k +1 and go back to step 3. 5. simulation results this section is dedicated to assess the performance of the proposed srwnn-based mrac in terms of control accuracy, robustness ability, and generalization to various input signals. in addition, a comparative study with other pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com omar farouq lutfy al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 107122 (2017) 114 controllers within the framework of mrac is conducted in this section. utilizing the mmais algorithm, the initial learning and the on-line design procedure discussed in sections 4.3 and 4.4, respectively, were employed to control all the considered plants. as the main parameters in the mmais algorithm, the mutation probability and the maximum number of iterations were set to 0.3 and 500, respectively. moreover, for all the controlled plants, only six wavelons (with selffeedback connections) were used to constitute the wavelon layer in the srwnn structure. these settings for the optimization algorithm and the srwnn structure were adequate to attain the required control performance. as mentioned before, the main contribution of this work is represented by the performance improvement achieved by the srwnn compared to the original wnn structure, as will be seen in section 5.5. furthermore, unlike the training method of the original wnn controller, an on-line training procedure is adopted in this work to further enhance the control performance and to realize an effective adaptive control strategy. 5.1. control performance tests to show the applicability of the proposed srwnn-based mrac to control various dynamical systems, three different nonlinear systems were adopted. these systems include a nonlinear non-minimum phase system, a water bath temperature control system, and a nonlinear minimum phase system. plant 1:this plant represents a nonlinear nonminimum phase system which is described by the following discrete-time equation [9]: (� + 1) = �(�)�(� − 1)1 + ��(�) + ��(� − 1) + �(�)+ 1.5(� − 1) … (19) as the reference model for the above system, the following equation is used: ��(� + 1) = 0.6��(�) + �(�) … (20) the srwnn-based mrac, shown in fig. 1, is required to track the following reference signal: (k) = 0.5sin �2πk150� + 1.2sin �2πk250� … (21) figure 3 (a) illustrates the result of controlling plant 1, while fig. 3 (b) shows the on-line adaptation made to the six weights connecting the wavelon and the output layers in the srwnn structure. a b fig. 3. plant 1 (a) outputs of the reference model and the controlled plant (b) on-line adaptation of the six weights in the srwnn structure. from fig. 3 (a), it is obvious that the proposed control approach has achieved an accurate control performance by following the desired reference model output. on the other hand, fig. 3 (b) demonstrates the on-line adaptation ability of the mmais algorithm in finding the optimal value for the six weights at each sampling time. furthermore, it is worth mentioning that the initial learning for the srwnn controller has resulted in a value of 0.1 for the performance index of equation (3) after 500 iterations, while the on-line training procedure has further reduced the above value to 0.015, which indicates the effectiveness of the on-line training procedure. plant 2: as the second nonlinear controlled plant, the water bath temperature control system is considered. this system is governed by the following discrete-time equation [36, 37]: �(� + 1) = �(��)y(k) + �(��)1 + ��.��(�)�� �(�)+ [1 − �(��)]�� … (21) where y(k) is the output temperature of the system in co , u(k) is the system control input, which is limited by the following bounds0 ≤u(k) ≤ 5 v, y0 is the room temperature in co y m , y -5 -4 -3 -2 -1 0 1 2 3 4 5 0 100 200 300 400 500 600 700 800 reference model controlled plant time samples w ei gh t 1 to w ei gh t 6 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 0 100 200 300 400 500 600 700 800 series1 series2 series3 series4 series5 series6 time samples b pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com omar farouq lutfy al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 107122 (2017) 115 ï ï ï î ïï ï í ì £< £<-+ £<-+ £<-+ £ = .12090,70 ,9070),70(5.060 ,7050),50(8.044 ,5030),30(5.034 ,30,34 )( k kk kk kk k kr ,a(t�) = e∗�� , andb(t�) = �� (1 − e���). as for the parameters of this system, the following settings were used: cy o25,40,1067973.8,1000151.1 0 34 ==´=´= -gba and t� = 30 s . these values have been adopted from a real water bath system [37]. the desired reference signal, which represents the desired water temperature in co , is given by the following signal: … (23) the desired system output is specified by the following first-order reference model equation [38]: y�(k + 1) = 0.6y�(k) + 0.4r(k) … (24) the actual system output, the reference model output, and the resulting control signal are exhibited in fig. 4 (a), while the on-line adaptation achieved on the six network weights is depicted in fig. 4 (b). a b fig. 4. plant 2 (a) outputs of the reference model and the controlled plant (b) on-line. as it is evident from fig. 4 (a), the actual system output has accurately followed the reference model output. figure 4 (b) clearly shows the on-line adaptation ability of the mmais algorithm at each sampling time. the initial learning for the controller after 500 iterations has achieved a performance index of 53.965, while the on-line training has further reduced this value to 21.393, signifying the efficiency of the on-line algorithm. bearing in mind the control signal limitation within a specific rang [0,5], it can be concluded that the proposed controller has achieved the desired performance even with the existence of such constraints. plant 3:this is a nonlinear plant expressed by the following difference equation [24]: �(� + 1) = �(�) + �(� − 1)1 + ��(�) + 2��(� − 1) + �(�) … (25) the desired system behavior is given by the following reference model equation: ��(� + 1) = 0.5��(�) + 0.3��(� − 1)+ �(�) … (26) while the reference signal is as follows: �(�) = 0.5[sin(10��) + sin (25��+ 0.5)] … (27) figure 5 (a) shows plant 3 output together with the reference model output, and fig. 5 (b) illustrates the on-line adaptation of the six network weights. a b fig. 5. plant 3 (a) outputs of the reference model and the controlled plant (b) on-line adaptation of the six weights in the srwnn structure y m , y -10 0 10 20 30 40 50 60 70 80 0 20 40 60 80 100 120 reference model controlled plant control signal time samples w ei gh t 1 to w ei gh t 6 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 0 100 200 300 400 500 600 700 800 series1 series2 series3 series4 series5 series6 time samples y m , y -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 0 10 20 30 40 50 60 70 80 90 100 reference model controlled plant time samples w ei gh t 1 to w ei gh t 6 -1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1 0 10 20 30 40 50 60 70 80 90 100 series1 series2 series3 series4 series5 series6 time samples pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com omar farouq lutfy al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 107122 (2017) 116 from fig. 5 (a), it can be seen that the srwnn-based mrac has done well in tracking the desired reference model output. the ability of the optimization method in adapting the network weights can be observed in fig. 5 (b). as with plants 1 and 2, the on-line training algorithm has achieved a smaller performance index value of 0.027, compared to the initial learning value of 0.057. 5.2. robustness tests these tests aim at investigating the robustness ability of the proposed srwnn-based mrac by conducting a disturbance rejection test on each plant considered in the previous section. for plants 1 and 3, a bounded disturbance of 50% from the controlled system output was applied for 10 samples at different periods of the simulation time. in particular, the disturbance was applied at the intervals 171161 ££ k , 371361 ££ k , and 771761 ££ k , for plant 1, and at the intervals 3930 ££ k and 6960 ££ k , for plant 3. for the water bath temperature control system, a disturbance of -3 co was applied at the 50th sample. it is interesting to notice that all of these disturbances were applied during only the controller testing phase of each plant. this means that the srwnn controller was not trained to handle these disturbances. nonetheless, the srwnn controller managed to cope with the unexpected effects of these disturbances by maintaining the desired output response for all the plants. figures 6 (a), (b), and (c) show the results of these tests for plants 1, 2, and 3, respectively. a b c fig. 6. outputs of the reference model and the controlled plant when a disturbance is applied at the output of (a) plant 1 (b) plant 2 (c) plant 3 objective functions against generations. it is noteworthy that the large disturbance amplitude, specifically the 50% of system outputs for plants 1 and 3, indicates that the srwnn controller possesses the ability to counteract large disturbances even when such disturbances are not encountered during the controller training phase. 5.3 parameter variation test this test is conducted to evaluate the controller ability in handling inherent changes in the system parameters. to perform this test, certain variations are made on a parameter in the water bath temperature control system at different time samples. more specifically, an increase of 10% in the original value of b(ts) in equation (22) was considered at sample numbers 30, 50, and 70. as was done in the previous section for disturbance rejection tests, the parameter variations were made only during the controller testing phase, which means that the controller was not trained to face these dynamic changes in the system. figure 7 illustrates the outputs of both the system and the y m , y -5 -4 -3 -2 -1 0 1 2 3 4 5 0 100 200 300 400 500 600 700 800 reference model controlled plant time samples y m , y -10 0 10 20 30 40 50 60 70 80 0 20 40 60 80 100 120 time samples reference model controlled plant control signal y m , y -3 -2 -1 0 1 2 3 0 10 20 30 40 50 60 70 80 90 100 reference model controlled plant time samples pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com omar farouq lutfy al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 107122 (2017) 117 reference model along with the control action of the controller. �(�) = 0.5[sin(15��)+ sin(35�� + 0.5)] … (29) fig. 7. outputs of the reference model and the controlled plant when a parameter variation test is applied on plant 2 objective functions against generations. as can be clearly seen from fig. 7, the srwnn controller has done well in tracking the desired reference model output even with the existence of an unexpected time-variant parameter in the system model. the control signal in fig. 7 indicates the adaptation made on the controller behavior to deal with such nonlinear time-variant system. 5.4 generalization tests the objective of these tests is to demonstrate the ability of the srwnn controller in handling reference signals different from those used in the controller training stage. this controller feature is known as the generalization ability. the tests were conducted on plants 1 and 3 by using the same training signals of equations (21) and (27) for plants 1 and 3, respectively. while, for the testing stage, the following signals were used: �(�) = 0.5��� �2��25 � + 1.2��� �2��100� … (28) equations (28) and (29) represent the testing signals for plants 1 and 3, respectively. the results of these tests are shown in fig. 8, where it is clear that the srwnn controller has appropriately generalized its learning to handle input signals which were not encountered throughout the controller training phase for plant 1, fig. 8 (a), and for plant 3, fig. 8 (b). a b fig. 8. outputs of the reference model and the controlled plant resulted from the generalization tests applied on (a) plant 1 (b) plant 3 objective functions against generations. 5.5. a comparative study with other related controllers in this section, the performance of the proposed srwnn controller is compared against those of other related controllers in terms of control accuracy and processing time. specifically, the controllers under consideration include the original wnn controller, the ann controller, and the modified recurrent network (mrn) controller. these controllers are used within the same mrac structure shown in fig. 1. for a fair comparison, the same mmais algorithm was employed to train each of the above controllers using the off-line procedure described in section 4.3. the structure of the original wnn controller [21] is similar to that of the srwnn discussed in section 3, with the exception of the wavelons' self-feedback connections and the initialization phase in the srwnn structure. on the other hand, the ann structure consists of an input layer, a hidden layer y m , y -10 0 10 20 30 40 50 60 70 80 0 20 40 60 80 100 120 time samples reference model controlled plant control signal y m , y -2.5 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 2.5 3 0 10 20 30 40 50 60 70 80 90 100 reference model controlled plant time samples y m , y -5 -4 -3 -2 -1 0 1 2 3 4 5 0 100 200 300 400 500 600 700 800 reference model controlled plant time samples a pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com omar farouq lutfy al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 107122 (2017) 118 with hyperbolic tangent as the neurons' activation functions, and an output layer. finally, the structure of the mrn, which was proposed in [39], has an input layer, a hidden layer, a context layer, and an output layer. the context layer has the same number of nodes as the hidden layer. each node in the context layer receives two inputs, the first of which represents a selffeedback connection with an adjustable weight, b , while the second input is the previous output of the corresponding hidden node multiplied by an adjustable weight, x . as the hidden nodes' activation functions, the hyperbolic tangent functions were used. in fact, the mrn is an improved version of the modified elman network [40]. it is worth to highlight that only 6 neurons were used in each hidden layer of the networks mentioned above. plants 1 and 3 used before are considered in this comparative study, along with the following time-delay nonlinear plant [21]: (� + 1) = 1.2(1 − ���.�)�(�)1 + ��(�) + �(� − 1) … (30) the mmais is classified as a stochastic algorithm, since it employs several random operators. as a result, the performance of a final optimized controller might vary for different simulation runs. hence, to achieve a reliable comparative study, 10 runs were conducted for each plant and the average result was taken. table 1 summarizes the results of this comparative study. as can be concluded from table 1, the proposed srwnn-based mrac has attained the best results with respect to the other controllers. in terms of control accuracy, the srwnn controller has achieved the least values for the performance indices for all the plants. regarding processing time, the srwnn controller took the shortest times except for plants 1 and 2 controlled by the original wnn controller. however, this slight increase in processing time for the srwnn, which was the result of including the selffeedback weights, can be ignored in light of the superior results of the proposed controller compared to the original wnn controller. 5.6. a comparative study on the optimization methods as stated earlier, it has been shown that the ais algorithm is superior to the ga with regard to maintaining good population diversity due to the efficient mutation operator employed by the ais algorithm [19, 20]. in this context, it is essential to compare the performances of both the mmais and the ga in training the proposed controller, and this section is dedicated for this purpose. as the controlled systems, the same plants considered in the previous section are used in this comparative study. similar to the comparison procedure followed in section 5.5, 10 runs were conducted for each plant and the average result was considered in order to attain a reliable comparative study. table 2 exhibits the comparison results. obviously, table 2 signifies the advantage of the mmais algorithm over the ga. in particular, the mmais algorithm has accomplished the least values for the performance indices and took the shortest processing times for all the plants compared to the ga. table 1, comparison results of the wnn, the ann, the mrn, and the proposed srwnn. mrac type criterion controlled plant plant 1 plant 2 plant 3 wnn-based mrac average performance index 0.636 1.261 0.386 average time (sec.) 57.775 57.709 9.603 ann-based mrac average performance index 1.625 2.258 0.085 average time (sec.) 71.341 75.574 12.085 mrn-based mrac average performance index 0.843 2.758 0.155 average time (sec.) 103.482 110.048 16.740 proposed srwnn-based mrac average performance index 0.052 0.913 0.039 average time (sec.) 58.928 62.028 9.327 pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com omar farouq lutfy al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 107122 (2017) 119 table 2, results of comparing the performances of the ga and the mmais in training the proposed srwnn-based mrac 6. conclusions in this paper, a srwnn-based mrac scheme is proposed to control nonlinear dynamical systems. as an improved version of a previously reported wnn structure, a srwnn structure is put forward by adopting a specific initialization phase and utilizing self-feedback weights in the wavelon layer. in addition, an on-line training procedure is followed to further enhance the control accuracy of the srwnn controller. to train the above controller, the newly developed mmais algorithm is employed to optimize the srwnn parameters. several nonlinear dynamical systems are used to show the effectiveness of the proposed control approach via an extensive evaluation tests, including control performance tests, robustness tests, parameter variation test, and generalization tests. all these tests have indicated the effectiveness of the srwnn-based mrac. furthermore, a comparative study with other related controllers has shown the superiority of the proposed controller. finally, as compared to the ga, the mmais algorithm has achieved better results with regard to control accuracy and processing time. 7. references [1] s. pankaj, j.s. kumar, and r.k. nema, “comparative analysis of mit rule and lyapunov rule in model reference adaptive control scheme,” innovative systems design and engineering, vol. 2, no. 4, pp. 154-162, 2011. 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[34] o. f. lutfy, and h. selamat, “wavelet neural network-based narma-l2 internal model control utilizing micro artificial immune techniques to control nonlinear systems,” arab. j. sci. eng., vol. 40, no. 9, pp. 2813-2828, 2015. [35] l. m. l.porter, and k. m. passino, “genetic model reference adaptive control,” proceedings of the ieee international symposium on intelligent control, columbus, usa, pp. 219-224, 1994. [36] c. -f. juang, and c.lo, “zero-order tsktype fuzzy system learning using a two-phase swarm intelligence algorithm,” fuzzy sets and systems, vol. 159, no. 21, pp. 29102926, 2008. [37] c. -t. lin, c. –h.chen, and c. -j. lin, “nonlinear system control using functionallink-based neuro-fuzzy networks,” in: yu, w. (editor) recent advances in intelligent control systems. springer-verlag london limited, 2009. 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[40] h. -w. ge, f. qian, y. -c. wellstead, w. –l. du, and l. wang “identification and control of nonlinear systems by a dissimilation particle swarm optimization-based elman neural network,” nonlinear analysis: real world applications, vol. 9, no. 4, pp. 13451360, 2008 pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com )2017( 107-122 صفحة ،2العدد ،13المجلد الھندسیة الخوارزمي جلةمعمر فاروق لطفي 122 نظام سیطرة متكیف ذو مودیل مرجعي مبني على شبكة عصبیة مویجیة ذاتیة التكرار باستخدام المناعة الصناعیة الدقیقة أنظمة **مریم حسن داود* عمر فاروق لطفي ةالتكنولوجی الجامعة /قسم ھندسھ السیطرة والنظم **،* 60157@uotechnology.edu.iq: *البرید االلكتروني mariam.hassan93@yahoo.com: **البرید االلكتروني ـةالخالص الشبكة . الالخطیة األنظمةمودیل مرجعي ذكي باستخدام شبكة عصبیة مویجیة ذاتیة التكرار للسیطرة على اذ ایقدم ھذا البحث نظام سیطرة متكیف وھذان . ھذا التحسین تم انجازه بتبني تعدیلین على ھیكل الشبكة االصلي، وبالتحدید. المقترحة ھي نسخة محسنة لشبكة عصبیة مویجیة منشورة سابقا العائدة لمویجات اإلشارةذاتیة أوزانتضمین وثانیا ، المثلى األوزانلتحسین االقتراب نحو قیم األوزاناستخدام مرحلة محددة لتولید أوالالتعدیالت یتضمنان تم استخدام نظام المناعة الصناعي ، طریقة تعلیمبوصفھا و. نظام السیطرة المقترح أداءتم اقتراح طریقة تعلیم انیة لتحسین ، ذلك فضال عن. الطبقة المویجیة وقد تم عرض كفائة الطریقة المستخدة بالسیطرة على عدة انظمة دینامیكیة . تخدمةالدقیق المعدل والذي طور حدیثا الیجاد القیم المثلى لمعامالت الشبكة المس . التعمیم وقد تم اعتماد عدة اختبارات تقییم لكل نظام مسیطر علیھ وھذه االختبارات تتضمن اختبارات اداء السیطرة و اختبارات المتانة واختبارات. الخطیة تم اجراء ، باالضافة لھذه اإلختبارات. كفائتھ من حیث دقة السیطرة و رفض المؤثرات الخارجیة وقابلیة التعمیمومن ھذه االختبارات اظھر النظام المقترح وقد . و الشبكة العصبیة الصناعیة والشبكة التكراریة المعدلة األصلیةدراسة مقارنة مع مسیطرات اخرى ذات صلة وبالتحدید الشبكة العصبیة المویجیة .األخرىدراسة تفوق المسیطر المقترح على المسیطرات اظھرت نتائج ھذه ال pdf created with pdffactory trial version www.pdffactory.com mailto:60157@uotechnology.edu.iq mailto:mariam.hassan93@yahoo.com http://www.pdffactory.com http://www.pdffactory.com al-khwarizmi engineering journal al-khwarizmi engineering journal,vol. 12, no. 2, p.p. 9099 (2016) performance enhancement of the south baghdad thermal station hussein wheeb mashi department of mechanical engineering / university of technology email: hussien _ mashi @yahoo com (received 3 june 2015; accepted 12 november 2015) abstract aim of the research is the study of improving the performance of the thermal station south baghdad and the main reasons for reduced its efficiency. south baghdad power planet comprises (6) steam turbine units and (18) gas turbine units .the gas turbine units are composed of two groups: the first group is made up of gas units (1,2), each of capacity (123) mw. the design efficiency of gas turbine units is 32%. the actual efficiency data of steam units is 18.3% instead of 45% which is the design efficiency. the main reason for efficiency reduction of gas units is the rejected thermal energy with the exhaust gases to atmosphere, that are (450-510) ℃.the bad type of fuel used (heavy) fuel. another reason for the low efficiency and has a negative impact on the steam and gas units. the actual efficiency that is calculated to set the first group gas unit (1) is (27%). suppose the steam is passed through the (hrsg) and this (hrsg) passes the combustion products emerging from first group gas turbine unit (1). the temperature of exhaust gases (tieg =783k) entered (hrsg) and the temperature of gas out from the (hrsg) (toeg =374k). the thermal efficiency of combined -cycle plant is ( the amount of fuel that can be available by using the plant compound in combined cycle, is (3603.88) tons per year. the relationship between the account of load and compression ratio during the three seasons of the year as where a large difference in the degree of heat between summer and winter .when the high temperature in summer less than the energy generated. as was the rate of energy produced is (99.8, 90.6, 70.6) mw in the (winter, autumn and summer), respectively. key word: steam turbine, gas turbine, combined cycle, south of baghdad, the thermal station. 1. introduction south baghdad power planet, consists of (6) steam turbine units and two groups of gas turbine units. the first group units (1, and 2) are of design capacity (123) mw. efficiency: is the percentage of the work (electric power) produced to the thermal energy from fuel consumed: …(1) overall efficiency is the sum of the efficiency of every component of the plant in regard of fuel consumption, thermal energy and mechanical energy transfer [1]. fuel is the main ingredient used in the liberalization of the energy as an element or a compound capable of generating energy through a chemical reaction, oxidant as in common applications or the fragmentation of the nucleus or merge with a so-called nuclear fuel [2]. the aim of every steam turbine design is an optimum and efficient operation characterizing an optimal energy conversion. overall efficiency of a steam turbine power plant, however, strongly depends on the turbine's performance. thus any improvement, however slight, can increase power availability, decrease equipment and component costs, and generate sizeable operating savings. today's highly competitive and deregulated market, optimizing steam turbine operation is no longer a goal but, rather, a necessity for power producers to remain competitive. a thorough evaluation of a turbine's design and operating condition can help increase a plant's efficiency by identifying improvements in one or more of three areas: 1. combustion to improve fuel utilization and minimize environmental impact. hussein wheeb mashi al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 9099(2016) 91 2. heat transfer and aerodynamics to improve turbine blade life and performance. 3. materials to permit longer life and higher operating temperatures for more efficient systems [3] .to increase the overall efficiency of electric power plants, multiple processes can be combined to recover and utilize the residual heat energy in hot exhaust gases. in combined cycle mode, power plants can achieve electrical efficiencies up to 60 percent. the term “combined cycle” refers to the combining of multiple thermodynamic cycles to generate power. combined cycle operation employs a heat recovery steam generator (hrsg) that captures heat from high temperature exhaust gases to produce steam, which is then supplied to a steam turbine to generate additional electric power. the process for creating steam to produce work using a steam turbine is based on the rankine cycle [4]. some of the proposed solutions to improve the efficiency of steam turbine and gas turbine units is taking advantage of thermal power rejected with exhaust gas, which is to benefit from a joint heat exchanger for two units of steam and gas to be combined thermal power plant which reduces fuel used and raise the efficiency. the advantages of combined cycle gas turbines are high power-to-weight ratio, smaller, fewer moving parts and less vibration than a reciprocating engine. other advantages include very low toxic emissions, runs on a wide variety of fuels, and high operating speeds. disadvantages are higher cost, longer start-up, less responsive to power demands, and a shrill whining noise. flexi cycle power plants combine the advantages of high efficiency in simple cycle and the modularity of multiple engines supplying the steam turbine. the use of appropriate fuel is another reason to raise efficiency. this is because using a heavy fuel oil (hfo) in the gas and steam units, affects efficiency. the disadvantage of (hfo) decreases boiler and combustion chamber efficiency, need to be stored, and heated in addition to the soot deposited on the internal surfaces of the tubes as well as the reduction in boiler pollutants [5]. the quality of the heavy fuel oil is largely determined by the crude oil grade and the refining process applied. this is the reason why heavy fuel oil of the same viscosity may differ considerably in quality from one bunker place to another [6]. heavy fuel oil normally is a mixture of residue oils and distillates. the components of the mixture often come from state of the art refining process such as vis-breaker of catalytic cracking plant. these processes may have a negative effect on the stability of the fuel and on its ignition and combustion properties. in this sense these factors also influence the heavy fuel oil treatment and the operating results of the engine. the properties of (hfo). are shown in table (1) [7]. table 1, the properties of h.f.o.[7]. s/n specification method bpc limit 1 density at 15°c kg/l astm d 1298 max. 0.991 2 viscosity at 50°c, cst astm d 445 max.180 3 water & sediment, % wt astm d 1796 max. 0.5 4 total sediment existent, %wt ip 375 max. 0.10 5 sediment by extraction, % wt. astm d 473 max. 0.10 6 sulphur content, %wt astm d 1552 max. 3.5 7 ash content, %wt astm d 482 max. 0.10 8 v, ppm ip 377 max.50 9 na, ppm ip 288 max. 16 10 asphaltenes, %wt ip 143 max. 14 11 flash point, °c astm d 93 max. 60 12 pour point, °c astm d 97 max.24 13 al, ppm ip 377 mod max. 30 14 lhv, kj/kg astm d 240 min. 39000 15 compatibility spot test astm d 4740 max. 2 16 water by distillation, % vol astm d 95 max. 0.50 as world energy demand recovers, it continues to drive power generation projects into ever expanding geographic regions and new areas of technology. the need to manage performance becomes increasingly more important. a comprehensive plan for efficiency improvements can typically yield multiple-percent output improvements at costs which are far lower than http://www.mpoweruk.com/images/rankine_pv.gif hussein wheeb mashi al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 9099(2016) 92 building new units. this helps the generation planning program for the fleet and can reduce or eliminate significant amounts of capital spending on new plant construction and all the issues and costs associated with bringing a new fossil-fired plant into the operating picture [8]. 2. calculations 2.1. calculation of the cycle efficiency the actual efficiency ) of the steam unit, is 18.3%. the actual efficiency ) calculated for unit number (1) for the first group type gas unit is 27%. the actual efficiency of gas turbine, is 66.8%. . photos (1-1) taken from the control center for first group gas unit (1) showing its operating conditions, and .table (2) presents readings of gas turbines units. table .2. readings were obtained for the first gas unit (1). unit rp t1 t3 m◦f kg/s m◦a kg/s power unit1 10.23 25 338 946.064 510 8.03 636.4 93.8 unit1 8.6 19 294 946.064 373 5.13 636.4 50.6 photo .1.1. taken from the control center for first group gas unit (1) showing its operating condition. 2.2. gas turbine power plants the first group gas unit (1) (fig 1). efficiency calculation is as follows: the heat supplied of the gas turbine (qgt): qgt = m◦a*cp* (t3 – ... ( (2 ( m◦f*c.v= m◦a*cp* (t3 – … (3) if c.v = 43000 kj/kg of h.f.o., cpg=1.1kj/kg*k and cpa=1.005 kj/kg*k then: 8.03*43000=m ◦ a*1.1*(t3-611) m ◦ a = … (4) net power = wt -wc … (5) net power =cpg*(t3 ) cpa*( -t1) … (6) t3 = 1154.24 k …(7) subs. eq. (7 in 4) we get: m◦a = kg /s… t2 = t1* = 578.12 k , t4 = t4 = the first group gas unit (1) efficiency: ac = = = 27% …(8) the efficiency of gas turbine: = (t3 – ) / (t3 – t4) …(9) = (1154.24 – 783) / (1154.24 – 594.96) = 66.85% hussein wheeb mashi al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 9099(2016) 93 fig. 1.t-s diagram for gas turbine [9]. 2.3. steam unite calculation the efficiency of steam turbine (fig. 2): …(10) increase in enthalpy of steam = …(11) = ( 3414.54 – 168.7 ) = 3245.77 kj/kg = = 593.97 kj/kg = = = ѵ* ( = 0.001 * ( 87.14 – 0.075) *100 (the compression work ) combined – cycle plant: the thermal efficiency of combined cycle plant:[10] …(12) fig. 2.t-s diagram for steam turbine. 2.4. calculation of the amount of fuel that can be provided in combined cycle according to the previous reading of the south baghdad station , the boiler efficiency reaches 43.2% ,the mass flow rate of steam (m◦s= 74.433 kg/s). this means that the efficiency of the boiler is very low. to impose. merge of the two plants; the steam plant and the gas plant to obtain the combined station is shown figure (4) and the t-c diagram is shown fig (3). suppose the steam is passed through the heat recover steam generator (hrsg) and this (hrsg) passes the combustion products emerging from first group gas turbine unit (1). the temperature of exhaust gases (tieg =783k) entered (hrsg) and suppose the temperature of gas out from the (hrsg) (toeg =374k).the choice of the best gas efficiency of the unit, which operates on (93.8 mw), the amount of fuel that can be provided by using the plant compound in combined cycle, is according to the following equation: the energy balance for (hrsg) gives: m◦g *cpg*( tieg toeg) = m◦s …(13) where: m◦a= 636.4 kg/s tieg= 783 k m◦s =74.433 kg/s. change in energy of gas in the (hrsg)(fig.3,4) : = m◦g *cpg*( tieg toeg) (635.6 + 8.03) *1.1*724 = 512586.9 kj 512586.9 = m◦s 74.4* ƞb= …(14) 43.2%= = 512590 29 / 183960 = 2.78 kgf/s ton in year fig.3.t-s diagram for combined cycle [11]. hussein wheeb mashi al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 9099(2016) 94 fig. 4. diagram of combined cycle.[12] 2.5. calculation of the relationship between load and compression ratio with time the readings were taken from the first group gas unit (1) as shown in the table (3) showing the relationship between load and compression ratio with time. figure (5,6) shows the peak load (in summer) is (81 mw), on 02/08/2013. figure (7,8) shows the peak load (in winter) is (102 mw), on 31/01/2014. figure (9,10) shows the peak load (in autumn) is (102 mw), on 27/10/2013. figure (5,6) shows that the high compression ratio of the first group gas units (1) rp = (9.92) when the temperature of primary t = 25 . the productive capacity was (79 mw). fig. 5.the relationship between load and compression ratio with time on 02/08/2013. hussein wheeb mashi al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 9099(2016) 95 1 2 3 4 5 6 7 8 9 10 11 12 rp 9.92 9 9.52 9 9.35 9.53 9.45 9.8 9.63 9.73 9.74 9.57 load(mw) 79 80 78 81 81 80 78 80 81 78 80 78 76 77 78 79 80 81 82 8.5 9 9.5 10 rp load(mw) linear (rp) linear (load(mw)) fig. 6. the relationship between load and compression ratio peak load (in summer) on 02/08/2013. fig. (7,8). where the compression ratio rp = 10.71 at the elementary grade temperature t = 18 was producing power (102mw). with rp = 11.11 and temperature t = 25 primary energy produced was (100mw). fig. 7.the relationship between load and compression ratio with time on31/01/2014. fig. 8. the relationship between load and compression ratio peak load (in winter), on31/01/2014. hussein wheeb mashi al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 9099(2016) 96 in autumn when the temperature is moderate, we find that the highest amount of compression ratio is rp = 10.66 and the load is (94mw). little reduction in the compression ratio leads to a small decrease in load. as in the figures (9and 10). fig. 9. the relationship between load and compression ratio with time in peak load (in autumn) on 27/10/2013. fig. 10.the relationship between load and compression ratio in peak load (in autumn) on27/10/2013. table.3 the relationship between load and compression ratio with time. one day the summer 02/08/2013 the winter 31/01/2014 the autumn 0/10/2013 time(h) rp load(mw) rp load(mw) rp load(mw) 8 9.92 79 10.99 100 10.6 96 10 9 80 10.93 100 10.66 94 12 9.52 78 11.06 100 10.49 90 14 9 81 10.99 100 10.27 90 16 9.35 81 10.98 100 10.32 88 18 9.53 80 10.71 102 10.53 88 20 9.45 78 10.8 97 10.55 89 22 9.8 80 11.11 100 0.008 90 24 9.63 81 8.91 50 0 0.2 26 9.73 78 8.69 48 0.008 0 28 9.74 80 8.59 50 0.008 0.1 30 9.57 78 11.19 100 0.008 0.1 calculations were made for the first group gas unit (1) to find the relationship between load and compression ratio in different months of the year , in (january, august, and october) where there is a hussein wheeb mashi al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 9099(2016) 97 difference between the atmospheric temperatures during the months, table (3),we found that the compression ratio is inversely proportional to the air temperature .at high air temperature, less compression ratio as the density of air becomes less and therefore less air into the compressor and that contribute to combustion. and the energy generated will be less, which calls for adding cooling system at high temperatures in the summer to increase the efficiency of the gas units. 3. results and discussion 1the actual efficiency ) calculated for unit number (1) for the first group type gas unit is 27% . the actual efficiency of gas turbine, is 66.85% . 2the efficiency of the combined cycle is (98.3)% by the station data available can be considered high, which means the possibility of improving the steam unit and gas unit efficiency. 3the amount of fuel that can be saved by using plant compound plant is estimated to be tons per year. this show the reduction in operating cost. 4table (2) shows that the high compression ratio of the first group gas units (1) rp = 10.23 when the temperature of primary t = 25 . the productive capacity is 93.8 mw. when, the compression ratio rp = 8.6 and the degree of primary temperature t = 19 then the produced energy be p = 50.6 mw. this means that the increase in compression ratio( rp) lead to increased energy despite the relatively high temperature. 5table (3), shown that the compression ratio is inversely proportional to the air temperature .at high air temperature, less compression ratio as the density of air becomes less and therefore less air into the compressor and that contribute to combustion. and the energy generated will be less, which calls for adding cooling system at high temperatures in the summer. 4. nomenclature symbol definition units heat capacity at constant pressure kj/kg.k cpa heat capacity of air at constant pressure kj/kg.k cpg heat capacity of gas at constant pressure kj/kg.k c.v calorie values of fuel kj/kg.k specific enthalpy of steam kj/kg mass flow rat of air kg/s mass flow rat of fuel kg/s mass flow rat of steam kg/s , qadd rate of added heat kj/kg rate of heat reject kj/kg rate of heat of gas turbine , rate of heat of steam turbine kj/kg t isentropic temperature at points (1, 2, 3, 4) k actual temperature at points (2) k actual temperature at points (4) k temperature of gas inlet in the (hrsg) k temperature of gas out from the (hrsg) k kj/kg actual gas turbine work. kj/kg turbine work kj/kg actual steam turbine work. kj/kg ac actual efficiency ƞb boiler efficiency ƞcc thermal efficiency of combined cycle iso isothermal efficiency heat ratio of air hrsg heat recover steam generator difference hussein wheeb mashi al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 9099(2016) 98 5. references , يذٌشٌح داس انُشش,"دتكُهىجٍا انىلى"جاتش شُشىل .د,جثانً [1] . 1981,انًىصم جايعح "يحطاخ تىنٍذ انطالح والتصادٌاتها "تاج انذٌٍ ضٍاء [2] .1980, ديشك, حهة [3] joseph a. macdonald "upgrading power plant efficiency," which appeared in the june 2003 issue of energy-tech magazine. [4] a. tica, , d. dumur supelec "combined cycle plant for power generation: introduction" ifac world congress milano 2011. دساسح تاثٍش استخذاو اَىاع يختهفح يٍ انىلىد عهى كفاءج [5] .وضاح حسٍٍ عثذ انشصاق : انًشجم انثخاسي [6] shvets. t.i.,tolbnsky, i.v., kirakovsky. f.v.,neduzhy a.i.sheudko. o.m.i."heat engineering" ,mir publishers moscow,1975. [7] 7-daniel r. schneider, željko bogdan" effect of heavy fuel oil/natural gas co-combustion on pollutant generation in retrofitted power plant "applied thermal engineering volume27, issues 11–12, august 2007, pages 1944–1950. [8] jyoti soni "properties of heavy fuel oil (hfo) hfo power plant"hfoplant.blogspot.com/2014/05/propert ies-of-heavy-fuel-oil-hfo.html. [9] rich vesel, "utilities can improve power plant efficiency and become emissioncompliant in the short term" abb inc ,02/01/2013.. [10] 10-rolph k. "combined-cycle gag and steam turbine power plant " penn well publishing company 1997. [11] search.viewcom. /search /imges ? qi = 1218&9=combined%20cycle%power %20plant&p=13&fcoi=bot. [12] searches.view.com/search/images?qsi=31/9= %20%20diagram%fc%20ombine%20cycle% 20power%%pl. ../../pavilion/downloads/effect%20of%20heavy%20fuel%20oil_natural%20gas%20co-combustion%20on%20pollutant%20generation%20in%20retrofitted%20power%20plant.htm ../../pavilion/downloads/effect%20of%20heavy%20fuel%20oil_natural%20gas%20co-combustion%20on%20pollutant%20generation%20in%20retrofitted%20power%20plant.htm http://www.sciencedirect.com/science/journal/13594311 http://www.sciencedirect.com/science/journal/13594311/27/11 2016)) 9099، صفحة 2، العذد12دجلة الخىارزمي الهنذسية المجلم حسين وهية ماشي 99 محطة جنىب تغذاد الحرارية اداءحسين ت حسين وهية ماشي انجايعح انتكُىنىجٍح / لسى انهُذسح انًٍكاٍَكٍح hussien _ mashi @yahoo com ًَانثشٌذ االنكتشو: لخالصة ا وحذاخ تخاسٌح و ( 6)تتأنف يٍ يحطح جُىب تغذاد. هذف انثحث هى دساسح تحسٍٍ اداء يحطح جُىب تغذاد انحشاسٌح واهى اسثاب اَخفاض كفائتها يٍغاواط, انكفاءج ( 123)لذسج كم واحذ ( 1,2)انًجًىعح انغاصٌح األونى تتكىٌ يٍ وحذتٍٍ : انىحذاخ انغاصٌح تتكىٌ يٍ يجًىعتٍٍ. وحذج غاصٌح( 18) االسثاب انشئٍسح نهحذ يٍ . نتً هً انكفاءج انتصًًٍٍح: ا45: تذال يٍ 18.3تٍاَاخ انكفاءج انفعهٍح نهىحذاخ انثخاسٌح هً . :32نهىحذاخ انغاصٌح جانتصًٍى , انُىع انسًء يٍ انىلىد انًستخذو ℃( 510-450)كفاءج انىحذاخ انغاصٌح انطالح انحشاسٌح انًطشوحح يع غاصاخ انعادو إنى انغالف انجىي انتً تكىٌ انكفاءج انفعهٍح انتً تى حساتها نهًجًىعح انغاص األونى انىحذج. سثة اخش فً اَخفاض انكفاءج ونه تاثٍش سهثً عهى انىحذاخ انثخاسٌح وانغاصٌح(. ولىد ثمٍم) يٍ ( 1) وحذجال انخاسجح يٍ ي تمطعه َىاتج االحتشاقانزيثادل حشاسي انثخاس انخاسج يٍ انًشجم خاللٌتى تًشٌش َفتشض أٌ % . (27)هً ( 1) انكفاءج ,كهفٍ( 384)كهفٍ وعُذ تشكها انًثادل انحشاسي ( 783)غاصاخ انعادو انذاخهه انى انًثادل انحشاسي دسجح حشاسج. انًجًىعح انغاصٌح االونى تى حساب انعاللح تٍٍ انحًم . طٍ فً انسُح ( 3603.88)وسج انًشكثح هً فشج تاستخذاو انذاتكىٌ كًٍح انىلىد انًتى, %(98.3 )انحشاسٌح نهىحذج انًشكثح عُذ استفاع دسجاخ ,تٍٍ انصٍف وانشتاء حٍث انفاسق فً دسجاخ انحشاسج كثٍش( 1) وَسثح االَضغاط خالل ثالثح فصىل يٍ انسُح نهىحذج انغاصٌح االونى .يٍغاواط فً انشتاء وانخشٌف وانصٍف عهى انتىانً( 70.6, 90.6,99.8)ج انحشاسج صٍفا تمم انطالح انًتىنذج ار اٌ يعذل انطالح انًُتج 110116 al-khwarizmi engineering journal,vol. 12, no. 1, p.p. shot peening time effect department of production (received abstract in this study many specimen s were (15*15*3) mm according to astm g71 minutes using steel ball having a diameter stress which were measured using x-ray diffraction m after peening. electrochemical corrosion test by tafel extrapolation method was carried out nacl solutions (sea water) where corrosion the obtained results show a favorable influence of sp treatment on compressive residual stresses and hardened surface layer since compressive stress was the highest keywords: aluminum, shot peening, surface roughness, residual 1. introduction aluminum and its alloys are being used successfully in a wide range of applications, from packaging to aerospace industries du good mechanical properties and low densities. in 2024 aluminum alloy copper was the main element in the alloys (cu) gives substantial increases in strength, permits precipitation hardening, reduces corrosion resistance, ductility and weld ability.[1,2] shot peening (sp) means bombarding a surface with spherical shot or beads, it treatment process aimed at increasing material’s fatigue strength. intense elastic to plastic deformation in the surface layer increases material fatigue properties by strain hardening an inducing favorable compressive residual stresses [3] the number of influential parameters on the shot-peening process is large: type, size and shape of the shots, time of peening, stream velocity, air pressure on the peened element, distance from nozzle to material surface (peening distance), nozzle angle, peening intensity and surface coverage percentage. experience showed that khwarizmi engineering journal,vol. 12, no. 1, p.p. 110116 (2016) peening time effect on corrosion behaviors of al zuhal abd alzahra production and metallurgy engineering / university of technology e-mail: zuhalabdalzahra@yahoo.com (received 1 february 2015; accepted 13 september 2015) s were prepared from 2024-t3 aluminum alloy for corrosion test by the dimensions of (15*15*3) mm according to astm g71-31 and then subjected to shot peening process at different time (15 diameter of 2.75 mm and rockwell hardness of 55rc to induce compressive ray diffraction method, surface roughness and hardness electrochemical corrosion test by tafel extrapolation method was carried out in where corrosion rate calculated using tafle equation. obtained results show a favorable influence of sp treatment on improving corrosion compressive residual stresses and hardened surface layer, the best corrosion resistance was at s since compressive stress was the highest. , shot peening, surface roughness, residual stresses, corrosion resistance aluminum and its alloys are being used successfully in a wide range of applications, from packaging to aerospace industries due to their good mechanical properties and low densities. in was the main element in the alloys (cu) gives substantial increases in strength, permits precipitation hardening, reduces corrosion resistance, ductility shot peening (sp) means bombarding a surface with spherical shot or beads, it is a surface treatment process aimed at increasing material’s fatigue strength. intense elastic to plastic deformation in the surface layer increases material fatigue properties by strain hardening an inducing favorable compressive residual stresses [3] e number of influential parameters on the peening process is large: type, size and shape of the shots, time of peening, stream velocity, air pressure on the peened element, distance from nozzle to material surface (peening distance), ning intensity and surface coverage percentage. experience showed that some of the parameters may be taken as constant while others must be evaluated through experiments and numerical simulations .shot peening is commonly conducted in a closed cabinet designed to safely confine the media and provide proper aiming of the shot blast stream [4]. the mechanism generating the compressive stresses in the surface layer is associated with the properties of treated materials. in the case of hard materials (hv�600), these stresses are generated by forces acting normal to the treated surface. the maximal tangent stresses stresses are situated underneath the surface, at the depth of (z = 0.47 * a) (fig.1 plastic (low-hardness) materials, such as aluminum alloys (hv �300), considerable plastic strains are generated near the surface. the increase of the size of the shot counteracted by the layer( b), which in consequence produces the internal stress distribution (fig.1 -b). the maximal value of compressive stress is registered on the surface of the worked product. thus generated state of stress will cause the changes in the structure of the al-khwarizmi engineering journal (2016) al alloy 2024-t3 university of technology orrosion test by the dimensions of at different time (15, 30, 45) induce compressive residual hardness were tested before and in an environment of 3 .5% oving corrosion resistance as induced he best corrosion resistance was at sp time of 30 minutes stresses, corrosion resistance. some of the parameters may be taken as constant while others must be evaluated through experiments and numerical simulations .shot peening is commonly conducted in a closed igned to safely confine the media and provide proper aiming of the shot blast stream [4]. the mechanism generating the compressive stresses in the surface layer is associated with the properties of treated materials. in the case of hard these stresses are generated by forces acting normal to the treated surface. the maximal tangent stresses ��max) due to normal stresses are situated underneath the surface, at the (fig.1-a). in the case of hardness) materials, such as 300), considerable plastic strains are generated near the surface. the increase of the size of the shot-peened layer( a) is counteracted by the layer( b), which in sequence produces the internal stress b). the maximal value of compressive stress is registered on the surface of the worked product. thus generated state of stress will cause the changes in the structure of the zuhal abd alzahra al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 110116 (2016) 111 surface layer, depending on the type of the worked material fig. 1 [5]. fig.1-a the pressure effect in accordance. fig.1-b the effect of plastic deformation with the hertz. fig. 1. compressive stress generation as a result of shot-peening process [5]. shot peening can only be reliably controlled and optimized by measuring the subsurface residual stress distributions produced. x-ray diffraction .(xrd) is the most accurate and best developed method of quantifying the residual stresses produced by surface treatments such as shot peening xrd offers a number of advantages when compared to the various mechanical methods, or the non-linearelastic ultrasonic or magnetic methods currently available. xrd is a linear-elastic method in which the residual stress in the material is calculated from the strain measured in the crystal lattice [6]. corrosion is a fundamental process which plays an important role in economics and safety. apparently corrosion cannot be avoided, but its severity can be reduced to a lower magnitude. the term 'aqueous corrosion' describes the majority of the most troublesome problems encountered when metal material is in contact with sea water. various methods have been employed to reduce corrosion. several techniques and methods have been developed to combat corrosion efficiency are continually being sought after, as a result of exorbitant amount spent on corrosion annually [7]. the objective of the present paper is to study the corrosion properties of sp treated highstrength aluminum 2024-t3 at different penning times. 2. experimental work chemical composition in weight % of 2024 t3 aluminum alloy which was conducted by using(thermo arl 3460, optical emission spectrometer) is listed in table (1). 20 specimens from this material were prepared in the dimensions of (15*15*3) mm according to astm (g71-31) to corrosion test. table 1, chemical analysis of the used metal aa (2024-t3. element wt% real value standard value al 92.6 rem ti 0 0-0.15 cr 0.05 0-0.1 zn 0.1 0-0.25 si 0.4 0-0.5 fe 0.3 0-0.5 mn 0.6 0.3-0.9 mg 1.5 1.2-1.8 cu 4.4 3.8-4.9 15 of these specimens were permit to shot peening 5 specimens for each time which was carried out at (15,30,45) min using spherically ball of 2.75 mm in diameter at constant distance between the nozzle and the specimen of 10 cm. the specimen is rotating continuously during peening to ensure 100%, the ball speed is 20 m/s. the shot peening device used was (shot tum blast control model (stb – ob) machine it was found in institute of technology fig(2) , preparing specimens were classified into four series, three of them corresponded to appropriate shot time as shown in table (2) zuhal abd alzahra al fig. 2. shot peening device with shot balls table 2, classification of corrosion test specimens. residual stress were measured for all specimens in table (2) by using lab xrd shimadzu x-ray diffracto meter, the residual stress results are shown in table(3) and fig.(3) gives the relation between 2 theta (deg ) which presented strain in brag law compressive residual stress in sin2^psi( deg.) presents the specimen location and its incline with the axis. specimen (a) symbol conditions a as received b shot peening for 15 minute c shot peening for 30 minute d shot peening for 45 minute 2 t h et a ( d eg .) sin2^psi( deg.) y=m*x+a al-khwarizmi engineering journal, vol. 12, no. 112 shot peening device with shot balls. classification of corrosion test specimens. residual stress were measured for all lab xrd-6000 meter, the residual stress results are shown in table(3) and fig.(3) gives the relation between 2 theta (deg ) which presented strain in brag law to calculate mpa ,while resents the specimen location specimen (b) specimen (c) specimen (d) fig. 3. photo graph of residual shot peening for 15 minute shot peening for 30 minute shot peening for 45 minute y=m*x+a 2 t he ta ( d eg .) 2 t he ta ( d eg .) y=m*x+a y=m*x+a 2 t he ta ( d eg .) 2 t h et a ( d eg .) 2 t h et a ( d eg .) 2 t h et a ( d eg .) , no. 1, p.p. 110116 (2016) specimen (b) specimen (c) specimen (d) photo graph of residual stress. y=m*x+a y=m*x+a sin2^psi( deg.) sin2^psi( deg.) sin2^psi( deg.) sin2^psi( deg.) zuhal abd alzahra al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 110116 (2016) 113 surface roughness the average value of the free surface roughness was measured using (perth meter) type (s6p) at the surface area of specimens( a) and peened area for specimens (b,c,d ) it is indicated by the parameter (ra) which is the center-line average of adjacent peaks, the macro hardness by using hardness tester waghtech international did vary depending on which peening treatment was used. results are shown in table(3) table (3) the result of rockwell b hardness, surface roughness and compressive residual stress. symbol hrb kg/mm2 surface roughness ra (µm) residual stress mpa a 76 0.016 -18 b 92 1.89 -162 c 120 2.2 -266 d 128 2.32 -206 (-) symbol referred to compressive stress and it has no effect on value corrosion test cell current readings were taken during a short, slow sweep of the potential. the sweep was taken from (-100 to + 100) mv relative to (ocp). scan rate defines the speed of the potential sweep in mv/sec and its taken (10 mv). in this range the current density versus voltage curve is almost nearly linear. the tests were performed by using a wenking mlab multi channels potentiostat and sci-mlab corrosion measuring system from bank electroniks-intelligent control gmbh, germany 2007, as shown in fig.(4) in this test, aluminum alloy (2024-t3) shot peened and un shot samples were used as working electrode (we), a saturated calomel electrode immersed in the salt solution was used as reference electrochemical corrosion test by tafel extrapolation method was carried out on all samples of all time (15,30,45)min shot peening in sodium chloride solution of 3.5% nacl with ph of 6.8 to determine corrosion parameters, such as corrosion potential (ecorr) and corrosion current ( icorr) at each time . these parameters will leads to calculate the corrosion rate according to the equation below [9]. c.r (m.p.y) = 0.13 * icorr * eq.wt / ρ (1) where m.p.y= mille-inches per year icorr=corrosion current density (µα/cm2) eq .wt =equivalent weight of the corroding species, ρ= density of the corroding specimens, (g/cm3). fig. 4. the electrochemical corrosion unit. the values for the corrosion potentials and corrosion current densities were estimated from the intersection of the anodic and cathode tafel lines. the corresponding corrosion potentials (ecorr), corrosion current density (icorr), anodic listed in table 4.and fig .(5) table 4, corrosion result for all specimens. symbol icorr [µa/cm2] ecorr [mv] corr. rate (m.p.y) a 50.57 -707 21.751 b 33 -750.2 14.19 c 7.2 -648.1 3.096 d 11.7 -617.9 4.803 corrosion rate=0.43 icorr fig. 5. electrochemical behavior polarization for all specimens. zuhal abd alzahra al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 110116 (2016) 114 sample (a) sample (b) sample (c) sample (d) fig. 6. corrosion photos. 3. discussion from chemical composition , in table (1) it is clear that copper is the controlling main element with percentage 4% , this was giving alloys good electrical conductively but poor corrosion resistance, it is often clad with aluminum or al-zn for protection [10] because of copper made for lower the hydrogen over voltage values since the hydrogen over voltage for copper and intermetallic compound is much lower than for aluminum in this case to the final corrosion potential is less noble than the initial value this might indicate that the material changed from the passive to the active state in furthermore this alloy shows much more general corrosion because copper waked the protective properties and anodizing use to improve the surface oxide stability when oxygen present in the aggressive medium is negligible [8, 11]. (table 3). show average surface roughness of base material (usp) sample (a) was 0.016 µm. it was found to be less as compared with the shot peened samples (b,c,d) shot peened contributed in increasing surface roughness which remaining hardness and compressive residuals stress to improvement mechanical properties and the shot time have more effect on its when increasing and this inagreament with nashwa [12] which study the effect of shot peening time with steel balls on mechanical properties of aa2024-t4 alloyresults showed an increase in yield and tensile strength values with increasing peening time up to 15 minutes table (4) shows corrosion results & fig.( 5 ) the polarization curves of the all specimen which classified in table(2),corrosion potential depends on the electrochemical behaviour of the microstructure and this is directly dependent on the quantity of the present phases for example in fig.(5) specimen (a) has a corrosion potential of 0.707v and a corrosion current of 50.57 µa/cm2 and the corrosion rate is 21.751 m.p.y and as the shot peen 15 min there is a decreasing in corrosion rate in small values, this is because of the comparative residual stress which formed by shot peened process cases in reduce the corrosion properties. specimen (b) fig .(5 )shows that for specimens c ,d as increasing in time of shots there is a decreasing in icor value and then corrosion rate . corrosion rate in specimen c, d is lower than it in specimen (a) inducing favorable compressive residual stresses layer which was increasing in depth with increasing in shot time this is because this layer act as oxide film productive in aluminum and its alloys when aluminum react with dissolve oxygen to form it this is partial matches with khaira salman [13] , she studied the effects of shot peening time on corrosion behaviors of aa 6061-t6 in aqueous solutions results shows a favorable influence of shot peening (sp ) treatment on corrosion resistance as induced compressive residual stresses lead to increase hardening of layer surface and decreasing in corrosion rate also ali[14] studied the effect of shot peening time on the mechanical corrosion spots zuhal abd alzahra al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 110116 (2016) 115 properties for two alumin um alloys aa2017t4 and aa6063-t5the results showed that the percent elongation are increased to maximum value at 9 minute for aa 2017-t4while the minimum value was at the same time for aa 6063-t5. fig. (6) shows the corrosion photos which insist the result above. 4. conclusion 1. shot peening with variable time contributed in decreasing corrosion rate. 2. the shot peening improves corrosion resistance of the alalloy 2024-t3 due to the homogenous cold worked surface layer and the compressive residual stresses produced during shot peening 3. aluminum alloys 2024-t3 has high corrosion rate because of the alloy elements such as copper. 4. the best shot time which contributed in improvement in corrosion rate is 30 min. 5. references [1] benachour m., hadjoui a., benguediab m., "heat treatment effect on fatigue crack growth", 3rd international conference on integrity, reliability and failure, portugal, 20-24 july 2009 . [2] mustafa kemal kulekci,” experimental comparison of mig and friction stir welding processes for en aw-6061-t6 (al mg1 si cu) aluminum alloy”, the arabian journal for science and engineering, 35, 2006, pp.321-330. [3] uroš zupanc1, janez grum2,”surface integrity of shot peened aluminum alloy 7075t651”,strojniški vestnik journal of mechanical engineering 57,5(2011), pp.379384 [4] roko markovina, branko blagojević ario ban,” investigation of influential parameters on shot-peening of aluminum alloys trends in the development of machinery and associated technology”, istanbul, turkey, 26-30 august, 2008 [5] a. fedoryszyn, p. zyzak,” characteristics of the outer surface layer in casts subjected to shot blasting treatment archive of metallurgy and materials “, vo.55 issue 3 year 2010 pp814-818 [6] paul s. prevéy,” x-ray diffraction characterization of residual stresses produced by shot peening theory and application”, series ed. a. niku-lari, iitt-international, gournay-sur-marne, france, 1990, pp. 81-93 [7] w. b. wan nik1, o. sulaiman , “corrosion behavior of aluminum alloy in seawater” the international conference on marine technology 11-12 december 2010, buet, dhaka, bangla [8] metals handbook, vol.2 properties and selection: nonferrous alloys and specialpurpose materials, asm international 10th ed. 1990. [9] annual book of astmstandards, standard practice for calculation of corrosion rates and related information, g102-89,vol. 03.02, 2004. [10] aluminum information at aircraftspruce.com accessed august 15, 2011. [11] r.a. higgins ,”engineering metallurgy part 1 “, applied physical metallurgy 4th edition universities press ltd (p340 – 353)1975. [12] nashwa abdul –hammied saad” effect of shot peening time on mechanical properties of aluminum alloy aa2024 –t4” the iraqi journal for mechanical and material engineering, vol.14, no1, 2014. [13] kharia salman hassan, abbas sheyaa alwan, sawsan abdulshaheed abbas,” corrosion behavior of al alloys 6061-t6 shot peening in different aqueous solution”, international journal of engineering and innovative technology (ijeit), volume 4, issue 8, february 2015. [14] ali a.ali1, esam a.ebrahim2 “effect of shot peening time on mechanical properties of aluminum alloys aa2017-t4 and aa6063t5” diyala journal of engineering sciencesvol. 06, no. 02, pp. 18, june 2013. �� 1، ا���د�12 �� ا���ارز�� ا������� ا�� ��ز ��� زھ�ة �� ،116 -110 )2016( t3-2024/.-�� ز�, ا�+*ف ��) ���ك ا�&%$ �#��"� ا!�����م ز ��� ا�0ھ�ة ��ج وا����دن ��� � ا�*�(� ا��)#'�'&%/ ھ#"! ا� zuhalabdalzahra@yahoo.com : ا�/�,و�. ا�-,+" ا��1�� (@�000000 و00000005? (3*15*15)<�<��000000د t3–12024=>000000%, ;0000000"د (7000000 ;%#�000000ت ا9�-�000000ر ا���/8000000 (70000000 !000000-%) ا��#%000000'م0000005. ھ4000000ه ا�"را!000000 �0000001 %0000000000!�%aا� b0000000000cا��'اastm-(g71-31) 0000000000b@�d) ذ+0000000000 و<�ز(�0000000000ن�0000000000,ات 5'(> 40000000000فa@� h0000000000i,�1 وان ھ40000000000ه ا��%#�0000000000ت)٤٥,٣٠,١٥ ( �'�%0000000" ا =rc٥٥hrc(@�0000000 وv0000000cد�u1 ) ٢.٧٥(د�%0000000a <'ا!p0000000 /0000000,ة (70000000 ا�0000000b'�ذ �0000000p, ھ�0000000 � �u0000000!�%� �00000001 .0000000�&�0000000uدات pw0000000i% وا� � ا��p000000=% وا�v000000zدة x-ray diffraction<'ا!�000000u& p000000ز y%000000'د ا��000000x ا��%#%000000 ']000000d�000000ر 8000000/�1 . و/�4000000[ �0000001 �%�000000س ا�-�ا&000000,ي ا9 و �0000000�y �00000001ب (�0000000"ل ا���/80000000 ) (�0000000ء ا�-=0000000,( %٣.٥/u,و/%�%�0000000وي <0000000a+,p ا��*�0000000uد ا��7/�0000000 00000005. (=@0000000'ل /@'ر+0000000" ا�0000000z'د+'م <0000000�# 800000/��<00000a+,p 8000005�1 و(700000 ا�#�de�00000 ا��00000. �000001 ا�=00000z'ل ;@%�00000u و&00000" ان ;�@%00000 ا�400000aف <��00000),ات ذات c�000001%, ا+*�a) 7%00000�=1 b00000@; .>�00000و(00000 ا� (7000000 وان ا�a) 8000000<5و(000000 �@��/h000000aa=1 8000000 ;#000000" ز. <�f-000000 ا�&�000000uدات ا�>pw000000% ا���'�000000"ةوان (�000000"ل ا���/8000000a+ 8000000 /@��000000 زاد ز(7000000 ا�4000000aف �h ذات �%�h%��; h ;#" ھ4ا ا�g(7 4�٣٠ف �/ h%pw<دات ا��u&�ن ان ا'(� a%د�. 116 (microsoft word \345\307\341\311 \346\343\307\345\321 1628) al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 15, no. 3, sptember, (2019) p.p. 1628 pneumatic control system of automatic production line using two method of scada/hmi implement plc hala helal hadi* maher yahya salloom** *department of automated manufacturing engineering/ al-khwarizmi engineering college/ university of baghdad **department of mechatronics/ al-khwarizmi engineering college/ university of baghdad *email: halahelal898@gmail.com **email: drmahir@kecbu.uobaghdad.edu.iq (received 17 april 2019; accepted 3 june 2019) https://doi.org/10.22153/kej.2019.06.006 abstract this study focuses on the implementation of interfaces for human machine interaction (hmi) control and monitor automatic production line. the automatic production line can performance feeding, transportation, sorting functions. the objectives of this study are implemented two scada/hmi system using two different software. tia portal software is used to build hmi, alarm, and trends in touch panel which is helped an operator to control and monitor the production line. labview software is used to build hmi and trends in the computer screen and is linked with microsoft excel (me) to generate information table helped to monitor the performance of the pneumatic equipment. the production line can do performance feeding, transportation, sorting functions, is designed and simulated in factory io software and implemented. s7-1200 plc employed to control the automatic production line using ladder logic diagram on tia portal v13 software. two methods are adopted to create human machine interface (hmi) for monitoring the status of the system (touch panel interface and labview interface). the communication between master program tia portal v15 software and slave program labview is through ole process control (opc) service. opc offers greater flexibility and lower costs of development, integration, and assembly for controlling and monitoring the industrial process, as well as opc involves a wide variety of data resource. as a result, the realized system enables two human interfaces for controlling and monitoring the physical values of the pneumatic system processes and parameters. in addition, it provides a way for different software packages to access values from control device (plc) assisting to monitor the performance of the pneumatic equipment. the implemented system can be applied the laboratory for reducing the distance between theoretical knowledge and practical applications for engineering students. it plays a significant role in developing the ability of innovation and practical application. furthermore, the implemented system of the production line is a prototype with an actual production situation which is very close to the actual environment control process in the factory. keywords: scada, hmi, pneumatic system, tia portal software, labview, plc. 1. introduction scada is an abbreviation of supervisory control and data acquisition. scada is the most modern tool used for collecting data designed to assist operators in the operation of the any system using real-time and historical information[1]. scada system task has data acquisition of the field devices, so it can process these data with the control systems, such as plc or rtu. the processing data is displayed as symbols, alarms, trends, and reports. the evolution and sophistication of current computing technology played an active role in scada system development. scada components have been hala helal hadi al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 1628 (2019) 17 made depending on the technology evolution. scada components are shown in figure (1). fig. 1. scada components. the hmi is connected to the scada supervisory computer to access live data to monitor the parameter, drive the diagrams, alarm handling and report generation[2] hmi can be a part of the computer program that communicates with the user, such as labview[3] or visual basic[4]. hmi can be a touch panel (hmi screen) which administers of the running components of the scada system[5].. hmi can also be web a server interface, as shown in figure (2) [6]. a contribution of this study is to use two methods for implementing scada/hmi to control and monitoring the pneumatic components applied in the manufacturing sector. fig. 2. hmi type. the pneumatic system is used in this work because the pneumatic components are simple in design, easily fitted, with relatively low maintenance cost (economic) and have long working life. it also unaffected by overload and do not produce heat [7] 2. methodlogy many steps are required for building the desired system starting from a vision or concept of the system design for defining the system, and the system function. after getting an idea for the design, the actual development of the system of hardware and software selection started to cost avoidance. also, the system is simulated to check whether the system can actually do its function. then the prototype of the production line is fabricated as shown in figure (3). hala helal hadi al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 1628 (2019) 18 fig. 3. the methodology. 3. the hardware components the important hardware components used to perform the scada/hmi will be described below: a. the production lines the production line consists of feeding unit, transforming unit and sorting unit. the feeding unit is the first unit of the system providing a work piece to other units. it mainly consists of work piece tube, push cylinder, proximity sensor and ir sensor, as shown in figure (4). fig. 4. the feeding unit. the transforming unit consists of the robotic arm employed to achieve the transfer function of the work piece in the production line and ir sensor for specifying the existence of the work piece, as shown in figure (5). fig. 5. the transforming unit. as the sorting unit consists of belt conveyer, push cylinder, inductive proximity sensor to detect metallic workpiece, dc motor to drive the conveyor belt and ir sensor to detect the existence of the work piece, as shown in figure (6). fig. 6. the sorting unit b. inductive proximity sensor proximity sensor has various ways to detect, including the use of electromagnetic induction caused by eddy current in the detection of metallic objects. the eddy current effect is that metal hala helal hadi al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 1628 (2019) 19 objects in an alternating magnetic field the metal produces internally alternating eddy current, and the eddy current will generate its magnetic field reactions on such a physical effect [8]. in the selection and installation of sensors. it should seriously be considered the detection distance, set distance to ensure a reliable production line of sensors moves. this distance varies from one type to another. c. infrared sensor (ir) an infrared sensor is an electronic gadget transmitted to detect a few parts of the environment. an ir sensor can quantify the warmth of an article and recognizes the movement, so it can recognize objects. the abundancy reaction of infrared (ir) sensors which is dependent on the reflected amplitude of the surrounding articles is non-straight and relies upon the reflection attributes of the item surface [9]. an ir sensor comprises of an ir led and an ir photodiode they both are called as photo – coupler. at this, point, when the ir transmitter emanates radiation, it achieves the article and a portion of the radiation reflects back to the ir collector. in view of the force of the gathering by the ir recipient, the yield of the sensor is characterized [10]. d. programmable logic control (siemens s7-1200 plc) the s7-1200 controller provides flexibility and power to control a wide variety of devices. the compact design, flexible configuration, and powerful instruction set combine to make the s71200 a good solution for controlling our system [11], as shown in figure (7). fig. 7. s7-1200 plc 4. implement the production line the system of automatic production line is made of steel structure, composed of feeding unit, transforming unit and sorting unit. each unit is connected mechanically and electrically with other units in the system to make automatic production line. each unit is mainly a pneumatic control system, but the conveyer belt is driven using dc motor, as shown in figure (8) and the system control diagram is shown in figure (9). fig. 8. the production line. hala helal hadi al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 1628 (2019) 20 fig. 9. the system block diagram. 5. design and implement scada/hmi system step7 tia portal software is used to control all units of automatic production line. in the first step, the tags of all digital and analogue inputs, outputs and timer were added as shown in figure (10). then, the ladder diagram (main ob) was built to do the required actions for this project as explained previously. after implementing the field instrument unit, process control unit and the master terminal unit, the hmi were consequently implemented as a result. two methods were used to represent other scada components (hmi, alarms, and trends). the first method was implemented by using tia portal software to form a touch panel screen. another method was implemented by using labview to form hmi screen in computer software. fig. 10. plc tags. a. touch panel interface for the implementation of the hmi in a touch panel, the software tia portal is used. tia portal is the engineering tool from siemens company adopted for programming, communication, diagnostics, testing and arrangement for s7-1200plc [10].in this study, tia portal software was used to automate the production line and build the scada/hmi system. first of all, the type of the touch panel was selected. then, the hmi tags were created and linked with plc tags. these tags were used to connect hmi panel with sensors and actuators on actual device. these sensors and actuators were connected with plc i/o port. hmi screen was designed to represent the actual system. hmi helped to visualize the values generated in the process. tia portal software is used for the implementation of the hmi, alarms and trends in touch panel, as shown in figure (11). hala helal hadi al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 1628 (2019) 21 fig. 11. hmi in touch panel. fig. 12. trend in touch panel. two alarms were sat up. the discrete alarm would be appeared if there were not enough number of the work piece in the feeding tube. moreover, the analog alarm would be showed as well if the pressure in pipes was higher than desired value, as shown in figure (13). fig. 13. alarm in touch panel. b. labview interface labview is framework building programming for applications from national instrument company required testing, estimation, and control with fast access to equipment and information experiences [12]. the labview system design software, software was used as a resource to perform the hala helal hadi al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 1628 (2019) 22 hmi interface through a pc; therefore, it allowed the programming of an environment helped to visualize the values collected in the process. these are presented in a graph to help the interpretation of the changes. after implementing and controlling the production line, the communication between the supervision unit (pc & hmi) and master terminal unit (software to program plc) may be implemented using niopc service. so, opc service was used to enable s7-1200 plc software (tia portal) to communicated with labview. opc service configuration can be described below a-open new channel. insert plc drive (siemns tcp ip). select network adapter (realtek pcle gpe [192.168.1.1]. b-then open new device. select device model (s7-1200). insert device id (192.168.1.100). c-finally, tag is added according to plc tag d-then value of tag automatic is added to opc client, hmi was designed and implemented on pc screen as shown in figure (14) and figure (15) shows the trend. hmi was implemented using labview software for monitoring the process of all units and the pneumatic components. labview was used as opc client while step7 tia portal is acted as opc server. fig. 14. hmi in pc screen. fig. 15. the trend in pc screen. hala helal hadi al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 1628 (2019) 23 6. result and discussion as a result, the realized system enables two human interfaces for controlling and monitoring the physical values of the pneumatic system processes and parameters, and provide away for different software packages to access values from control device (plc) which helps to monitor the performance of the pneumatic equipment. two scada/hmi system were implemented using two different software. tia portal software used to build hmi, alarm, and trends in touch panel which helped the operator to control and monitor the production line. labview software was utilized to build hmi and trends in the computer screen and was linked with microsoft excel to generate the pressures to pressures drop information table helped to monitor the performance of the pneumatic equipment. 1when the start switch was pushed and there are enough number of the work piece in the feeding tube, the feeding cylinder was set to push the work piece to the waiting tube, as shown in figure (16) which displays the tia portal interface and labview interface a-tia portal interface. b-labview interface fig. 16. two hmi result of feeding unit start. hala helal hadi al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 1628 (2019) 24 2-when the work piece reached the waiting station. the feeding cylinder out was reset and feeding cylinder rearward was set as well. in addition to the robotic arm that moved to the left direction (left cylinder set and right cylinder reset) and forward (forward cylinder set and rearward cylinder reset); then, the griper clamped the work piece (the clamping cylinder set and unclamping cylinder reset) as shown in figure (17) a-tia portal screen blabview screen fig. 17. two hmi result robotic arm started. 3the robotic arm moved to right side (right cylinder set and right cylinder reset). when the robotic arm got to right side the gripper unclamped the work piece (the unclamping cylinder set and clamping cylinder reset). finally, the robotic arm moved to rearward (the rearward cylinder set and forward cylinder reset) and the conveyer at sorting unit started as shown in figure (18). hala helal hadi al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 1628 (2019) 25 a-tia portal screen. blabview screen fig. 17. two hmi result robotic arm stop and sorting conveyer start. 4if the work piece was metallic, the conveyer would be stopped (reset) and the sorting cylinder was on(set), as shown in figure (19). hala helal hadi al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 1628 (2019) 26 a-tia portal screen. blabview screen. fig. 19. two hmi result sorting cylinder start 7. the conclusion to design the fabrication of the automatic production line and robotic arm which is driven by the pneumatic system. building hmi/scada by using two methods: the touch panel interface and computer interface utilizing diverse software for the programming of each of them facilitating the immediate monitoring. tia portal software is used to build (hmi, alarm, and trends) in touch panel helped the operator to control and monitor the production line. labview software is applied to build hmi and trends in the computer screen and is linked with microsoft excel (me) to generate the pressures to pressures drop information table helped to monitor the performance of the pneumatic equipment. success of monitoring the pneumatic system components (compressor, valves, cylinders and compressed air distribution network). success of enabling the commutation between the master software (tia portal) with slave software (labview) by using niopc service. the project can be customized to suit any other industrial requirements. thus, this method can be used to automate any industrial process to develop the manufacturing sector. hala helal hadi al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 1628 (2019) 27 8. reference [1] stouffer, keith, and joe falco. "guide to supervisory control and data acquisition (scada) and industrial control systems security." computer security division information technology laboratory, md 20899-8930 2006. [accessed jun,2018]. [2] alphonsus, ephrem ryan, and mohammad omar abdullah. "a review on the applications of programmable logic controllers (plcs)." renewable and sustainable energy reviews, vol.60, p.p1185-1205, 2016. [3] l. a. sabri, s. a. mohammed, and m. i. issa, “design of scada system for oil pipeline control using labview,” al-nahrain journal for engineering sciences, vol. 20, no. 3, pp. 600–614, 2017. [4] v. b. kumbhar, d. gokhale, v. s. kumbhar, and m. k. patil, “implementation of customised scada for cartoner packaging machine for cost effective solution,” international research journal of engineering and technology, vol.4, issu.01, pp. 996–1001, 2017. [5] ahmed khalfalah abdel-rahman, mohamed mustafa alkhedir, and zeid abdel-rahman adam. "smart scada system for manufacturing sugar process". m.s thesis, university of sudan of science and technology, 2015 [6] mohamed endi, y z elhalwagy, attalla hashad. "three-layer plc/scada system architecture in process automation and data monitoring", presents at 2nd international conference oncomputer and automation engineering, singapore, singapore ,2010. [7] salloom, m. y. and khaleel r. n. "stabilizing gap of pole electric arc furnace using smart hydraulic system" al-khwarizmi engineering journal, vol. 11, no. 1, pp. 11-18, 2015. [8] b. george, h. zangl, t. bretterklieber, and g. brasseur, “a combined inductivecapacitive proximity sensor for seat occupancy detection,” ieee transactions on instrumentation and measurement information, vol. 59, no. 5, pp. 1463–1470, 2010. [9] b. denkena, h. c. möhring, and k. m. litwinski, “design of dynamic multi sensor systems,” prod. eng., vol. 2, no. 3, pp. 327–331, 2008. [10] ruser, heinrich. "object recognition with a smart low-cost active infrared sensor array",presented at 1st international conference on sensing tech, november 21-23, 2005 palmerston north, new zealand ,2005. [11] zhang, wei, and shuai sun. "design of automatic feeding control system in tank area based on siemens plc." ,presented at 2018 chinese control and decision conference ieee, shenyang, china, july 2018. [12] amer al-mesaody, programming pneumatic processes sequence based on plc by demonstration, " al-khwarizmi engineering journal, vol. 09, no. 1, pp. 46-54, 2017. )2019(1628 ، صفحة 3، العدد15دجلة الخوارزمي الهندسية المجلم هالة هالل هادي 28 تنفيذ نظام مراقبة واشراف وتحكم لخط انتاجي ألي بطريقتين باستخدام المنطقي المبرمج المتحكم ماهر يحيى سلوم** هاله هالل هادي* جامعة بغداد /كلية الهندسة الخوارزمي /قسم هندسة التصنيع المؤتمت* جامعة بغداد /كلية الهندسة الخوارزمي /**قسم هندسة الميكاترونكس gmail.com898halahelal@ :*البريد االلكتروني drmahir@kecbu.uobaghdad.edu.iq البريد االلكتروني:** الخالصة ) للتحكم ومراقبة خط اإلنتاج التلقائي. خط اإلنتاج األوتوماتيكي الذي يمكنه أداء وظائف hmiركز هذا العمل على تنفيذ واجهات المستخدم الرسومية ( إلنشاء واجهة tia: تنفيذ نظام اشراف ومتابعة وتحكم باستخدام طريقتين مختلفين. يستخدم برنامج أهداف هذا العمل ، النقل ، الفرز للقطعة المصنعة. التغذية يقة الثانية باستخدام برنامج المستخدم الرسومية واإلنذار والجداول البيانية في لوحة اللمس مما ساعد المشغل على التحكم في خط اإلنتاج ومراقبته. اما الطر labview )إلنشاء واجهة المستخدم الرسومية واالجداول البيانية في شاشة الكمبيوتر وتم ربطه بmicrosoft excel إلنشاء جدول معلومات الذي ( للتحكم في القيم الفيزيائية لعمليات ومعلمات النظام الهوائي نتيجةً لذلك ، يمّكن للنظام تحقيق واجهتين رسوميتين يساعد الصيانة في مراقبة أداء المعدات الهوائية. يمكن ) مما يساعد على مراقبة أداء معدات التي تعمل بالهواء المضغوط.plc(ومراقبتها ، ويوفر حزم برامج مختلفة للوصول إلى القيم من جهاز التحكم لنظرية والتطبيقات العملية لطالب الهندسة، وسوف يلعب دوًرا مهًما في تطوير قدرة االبتكار استخدام النظام المطبق في المختبر لتقليل المسافة بين المعرفة ا .الفعلية في المصنع والتطبيق العملي. باإلضافة إلى ذلك ، يعد النظام المطبق لخط اإلنتاج نموذًجا أولًيا له وضع إنتاج حقيقي قريب جدًا من عملية التحكم 6572 khwarizmi engineering journal, vol. 1-al f corrosionointeraction f 1100o alalkawi h.j.m department of electromechanical engineering/ university of technology * materials engineering/ fdepartment o ***,** ***e (received abstract corrosion-fatigue occurs by the combined actions of cyclic loading peening on cumulative corrosion-fatigue life of 1100 were submerged in 3.5%nacl solution for 71 days. constant fatigue tests were performed with and without corrosive environment. cumulative corrosion-fatigue tests were also carried out in order to determine the fatigue life before after shot peening. the constant fatigue life was fatigue limit was reduced by 13% compared with dry fatigue. in case of shot life was increased by a factor of about (2) compared with cumulative corrosion found that the cflif%(cumulative fatigue life improvement factor) was about (2 treatment . keywords: corrosion -fatigue , shot peen 1. introduction if the metals are exposed to the concurred actions of repeated stress and corrosive environment, then its fatigue behavior will become quite different from that in air ,it means that there is a significant decrease in fatigue strength and fatigue life[1].in case of light metals the presence of corrosion is known to reduce their strength significantly ,thus it does great harm to engineering structural integrity of frames ,especially those working in marine environment [2]. the combined action of corrosion an repeated stresses defined by corrosion fatigue .the effect of corrosive actions on a metal surface may cause a general roughening to the surface and lead to the generation of crevices and pits at different points on the surface which result in a greater loss in fatigue strength of the metal when it subjected to fluctuating stresses at the same (201 72 -65, p.p. 1, no. 1khwarizmi engineering journal, vol. 1 nd shot peening acumulative fatigue -f corrosion aluminum alloy h12-f 1100 dmaajee amer hameed *alalkawi h.j.m zainab azeez betti*** department of electromechanical engineering/ university of technology mustansiriya university -alcollege of engineering/ materials engineering/ alalkawi2012@yahoo.com :mail-*e amer.h.m.altaee@gmail.com :mail-**e faithful_mind1990@yahoo.com :mail-***e 2014) october 282014; accepted may 11(received atigue occurs by the combined actions of cyclic loading and corrosive environment fatigue life of 1100-h12 al alloy was investigated. before f solution for 71 days. constant fatigue tests were performed with and without corrosive fatigue tests were also carried out in order to determine the fatigue life before after shot peening. the constant fatigue life was significantly reduced due to corrosive environment and the endurance fatigue limit was reduced by 13% compared with dry fatigue. in case of shot peening the cumulative , corrosion increased by a factor of about (2) compared with cumulative corrosion-fatigue life without shot peening. that the cflif%(cumulative fatigue life improvement factor) was about (2-6) due to shot peening surface fatigue , shot peening , 1100-h12 al alloy, cumulative fatigue damage if the metals are exposed to the concurred actions of repeated stress and corrosive environment, then its fatigue behavior will become quite different from that in air ,it means that there is a significant decrease in fatigue n case of light metals the presence of corrosion is known to reduce their strength significantly ,thus it does great harm to engineering structural integrity of frames ,especially those working in marine environment [2]. the combined action of corrosion and repeated stresses defined by corrosion fatigue .the effect of corrosive actions on a metal surface may cause a general roughening to the surface and lead to the generation of crevices and pits at different points on the surface which result in a loss in fatigue strength of the metal when it subjected to fluctuating stresses at the same time, than when each factor acts separately. corrosion fatigue is considered as the reason of a wide variety of failures in service, including, for example, marine propeller shafts, boiler and superheater tubes, turbine and pump components, and pipes carrying corrosive liquids,...etc. [3]. one of the most important remedies for corrosion fatigue is shot peening a process in which a round metallic thrown on the metal surface at a relatively high velocity(10-40m/sec) and it also known as acold working method . each shot makes a small dent in the metal surface . a plastic flow of the surface grains is generated by the shot impact. there is a several parameters that affect on this process such as (the kinetic energy , impinging angle of the shot impact , the physical properties of the surface (hardness , toughness),...etc). fatigue failure, (which cause about 90% of the mechanical catastrophic khwarizmi-al engineering journal )5(201 nd shot peening ** d department of electromechanical engineering/ university of technology mustansiriya university and corrosive environment. the effect of shot al alloy was investigated. before fatigue testing, specimens solution for 71 days. constant fatigue tests were performed with and without corrosive fatigue tests were also carried out in order to determine the fatigue life before and significantly reduced due to corrosive environment and the endurance peening the cumulative , corrosion -fatigue tigue life without shot peening.it was 6) due to shot peening surface . time, than when each factor acts separately. corrosion fatigue is considered as the reason of a wide variety of failures in service, including, for propeller shafts, boiler and superheater tubes, turbine and pump components, and pipes carrying corrosive liquids,...etc. [3]. one of the most important remedies for corrosion fatigue is shot peening .shot peening is a process in which a round metallic shot is thrown on the metal surface at a relatively high 40m/sec) and it also known as acoldworking method . each shot makes a small dent in the metal surface . a plastic flow of the surface grains is generated by the shot impact. there is a several parameters that affect on this process such as (the kinetic energy , impinging angle of the shot impact , the physical properties of the surface (hardness , toughness),...etc). fatigue failure, (which cause about 90% of the failures in metal parts )(2015 72 -65khwarizmi engineering journal, vol. 11, no. 1, p.p. -al alalkawi h.j.m 66 and structures) largely start at surface cracks that grow under tensile stresses ;thus shot peening generally results in considerably greater fatigue strength because the residual compressive stresses caused by shot peening will counteract the applied tensile stresses on the metal surface[4]. menan and hénaff [5]investigated the interactions between mechanical, environmental and microstructural parameters during corrosion fatigue crack growth of 2024 al alloy using 3.5% nacl solution .it was found that the corrosion crack growth rate is higher in nacl solution than in air or distilled water. alalkawi et al.[6] examined constant and cumulative fatigue test under the effect of shot peening treatment for two aluminum alloys 2024 and 5052 .it was concluded for 2024 al alloy that as the shot peening time increases the cumulative fatigue life is improved but above 10 min. the fatigue life is reduced .while shot peening reduced the fatigue life of 5052 al alloy. gao.y.k. [7] studied the fatigue behavior of 7050-t7451aluminum alloy for machined ,laser and shot peened specimens . results indicated that laser and shot peening improve the fatigue life and strength compared to the unpeened results. dong et al. [8] predicted the effect of prior corrosion on the crack propagation of aluminum alloy based on scanning electron microscope (sem).results indicated that corrosion pits increases the crack growth rate which can be empirically expressed by the term of ( ak n maxσ ). ford. f.p.[9] studied the corrosion fatigue crack propagation rates for aluminum-7% magnesium. it is suggested that the cracking mechanism is slip dissolution and the rate determining steps increase the crack growth. laurino et al.[10] studied the fatigue behavior of 6101 al alloy under corrosive media and it was found that corrosion -fatigue interactions reduced the fatigue life of the 6101 al alloy. the main goal of this work is to report experimental evidence about the constant fatigue and fatigue damage accumulation behavior of 1100h12aluminum alloy under corrosion fatigue and studying the effect of shot peening process on the mechanical behavior of the mentioned alloy. 2. experimental procedures aluminum of the 1100-h12 class is used in the current work and it is primarily used in applications where electrical conductivity , formability , ductility , and the resistance to stress corrosion are more important than strength. chemical analysis of the metal used was tested at ( state company for inspection and engineering rehabilitation(sier) in iraq).the results, which are compared to the american society for testing and materials (astm b209) [11], are summarized in table (1) below while the mechanical properties are listed in table (2) . table 1, chemical composition of 1100 al alloy in wt%. *other elements include (cr ,ni, ti ,pb, co)when tested experimentally they found to be in the following percentages (0.003, 0.002, 0.006 ,0.0006, 0.001) respectively. table 2, mechanical properties of 1100 al alloy. alloying element% si fe cu mn mg zn other elements* la ]11b209 [ astm 0.95 0.2 -0.05 0.05 0.05 0.1 0.15 rem measured 0.112 0.447 0.3 0.017 0.004 0.015 0.0126 rem property ultimate tensile strength mpa yield strength mpa elongation % in 100 mm modulus of elasticity gpa astm b209[11] min.= 96.5 min.=75.8 min.=6 70 measured 107 82 7 71 alalkawi h.j.m 3. testing procedures 3.1. tensile testing the experimental mechanical properties listed in table (2) above were measured using (wdw 200e) tensile test apparatus with a capacity of 200kn. the tensile specimen was taken according to american society for testing and materials (astm b209) .shape and dimensions of the tensile specimen is illustrated in fig.1. tensile test specimen according to astmb209. 3.2. fatigue testing the avery fatigue testing machine type 7305 was used to apply reverse loads with or without an initial static load as shown in figure (2). the fatigue test is a cyclic bending loading procedure with r=-1. the purpose of the test is to generate s-n data (stress vs. number of cycles) for metal used. fig. 2. fatigue testing machine shape and dimensions of fatigue test specimen is shown in figure (3) below: khwarizmi engineering journal, vol. 11, no. 1, p.p. -al 67 the experimental mechanical properties listed in table (2) above were measured using (wdw200e) tensile test apparatus with a capacity of specimen was taken according to american society for testing and terials (astm b209) .shape and dimensions of the tensile specimen is illustrated in figure (1) . tensile test specimen according to the avery fatigue testing machine typewas used to apply reverse loads with or without an initial static load as shown in figure the fatigue test is a cyclic bending loading 1. the purpose of the test is to data (stress vs. number of cycles) for achine. of fatigue test ) below: fig. 3. shape and dimensions all dimensions in mm) d3479/d3479m–96 standard 3.3. corrosion test the specimens before fatigue testing were immersed in a 3.5%nacl solution for (71 especially those serving in marine environment (sea water)[12]. 3.4. shot peening procedure the specimens were shot peening treated from using tumbleset control all sides ob machine no. 03008 -model stb tusraappa propertieswith the following verage ball size = 0.6 mm a = cast steel ball material rockwell hardness = ( 48 bars. = 12 pressure = 40 m/sec . velocity shot peening is carried out on fatigue specimens at different time intervals which are (10 , 20, 30 ) minutes. the is shown in figure (4) below fig. 4. shot peening apparatus )(2015 72 -65khwarizmi engineering journal, vol. 11, no. 1, p.p. imensions of fatigue specimen ( ) according to astm 96 standard the specimens before fatigue testing were nacl solution for (71)days especially those serving in marine environment peening procedure the specimens were shot peening treated from anel pusing tumbleset control ob machine no. 03008 : properties . verage ball size = 0.6 mm . = cast steel )hrc . 50 -rockwell hardness = ( 48 is carried out on fatigue specimens at different time intervals which are he shot peening apparatus below: shot peening apparatus. alalkawi h.j.m 4. experimental results and discussion 4.1. fatigue results fatigue analysis are normally based on the results obtained from constant amplitude table 3, fatigue results. theta � °� � specimens no. 12° 1,2,3 10° 4,5,6 6° 7,8,9 4° 10,11,12 12° 13,14 ,15 10° 16,17 , 18 6° 19,20 ,21 4° 22, 23, 24 from the table (3) above ,it is clear that there is no effect of corrosion on fatigue life at lcf(low cycle fatigue) .the reason of this finding is due to dominate parameter of the applied load .while the corrosion is not significantly influence on the fatigue life[ following figure (see ,fig.5), indicate that the fatigue life of pre-corroded specimens d compared with that of as-received specimens also the fatigue strength is reduced by a factor of 13% compared with dry fatigue strength . an approximately 60% decrease in fatigue strength of 7075-t6 a l-alloy was found by genel[ the same conditions of the present work. the conventional ,constant stress amplitude s n curves for the above conditions are shown in the following figure (see, fig. 5) : fig. 5. conventional ,constant stress amplitude s curves for dry and corrosion fatigue conditions khwarizmi engineering journal, vol. 11, no. 1, p.p. -al 68 nd discussion atigue analysis are normally based on the from constant amplitude continuous cycling tests. thus , the first step of work was to establish the base specimens (dry fatigue ) and 12 specimens for( corrosionfatigue) which were immersed in 3.5% nacl solution for 71 days .the resu tabulated in table (3) as shown below: dry condition nf cycles applied stress mpa 19000 , 14000, 16500 441 21000, 27000, 24000 393 276000 , 211000 ,245000 195 2713000, 2870000 ,2960000 (unfailed specimens ) 137 71 days corrosion condition 13000 , 14000 , 18000 441 23000 , 24000 ,22000 393 252000 , 209000 , 233000 195 684280 , 688740 , 693200 137 ,it is clear that there is no effect of corrosion on fatigue life at ) .the reason of this finding is due to dominate parameter of the applied load .while the corrosion is not significantly influence on the fatigue life[13]. the indicate that the corroded specimens decreased received specimens. also the fatigue strength is reduced by a factor of 13% compared with dry fatigue strength . an approximately 60% decrease in fatigue strength of was found by genel[14] using conditions of the present work. ,constant stress amplitude sn curves for the above conditions are shown in ,constant stress amplitude s-n curves for dry and corrosion fatigue conditions. the s-n curves has been used by several workers to evaluate the cumulative fatigue damage .the endurance limit at 10 reduction factor for dry and corrosion fatigue conditions are shown in table (4). p.s.pao et al. [13]tested 7075-t351 aluminum alloy under fatigue loading using the 3.5%nacl solution as a medium. they found that the threshold stress levels are significantly reduced due to the presence of corrosion pits. the presence of a corrosive environment during fatigue loading eliminates the fatigue limit for the metal used [15]. )(2015 72 -65khwarizmi engineering journal, vol. 11, no. 1, p.p. continuous cycling tests. thus , the first step of work was to establish the base line data for 12 specimens (dry fatigue ) and 12 specimens for( fatigue) which were immersed in 3.5% nacl solution for 71 days .the results are table (3) as shown below: nf , average 16500 24000 244000 2847667 2713000, 2870000 ,2960000 15000 23000 231333 688740 n curves has been used by several workers to evaluate the cumulative fatigue damage .the endurance limit at 107 cycles and reduction factor for dry and corrosion fatigue conditions are shown in table (4). p.s.pao et al. t351 aluminum alloy under fatigue loading using the 3.5%nacl solution as a medium. they found that the threshold stress levels are significantly reduced due to the s. the presence of a corrosive environment during fatigue loading eliminates the fatigue limit )(2015 72 -65khwarizmi engineering journal, vol. 11, no. 1, p.p. -al alalkawi h.j.m 69 table 4, .actorfeduction rnd aycles c 7t 10aimit lendurance 4.2. cumulative fatigue damage results most engineering components in service are subject to a complex , non-constant ,state of stress .each cycle or group of cycles at a particular amplitude induces damage to the component : the addition of all this damage is called cumulative damage (cd) .in laboratories ,cd is usually examined by testing specimens with a definite number of cycles at one stress level ,and then to continue the test at other stress levels till failure [16] cumulative fatigue results for 71 days corrosion are listed in table (5) below: table 5, cumulative fatigue results for 71 days corrosion. table (6) illustrate the cumulative corrosionfatigue with the interaction of shot peening at different times of peening. 6, table .interaction of 71 days cumulative corrosion fatigue with shot peening for different times shot peening time -10 min average f n nf loading sequence (mpa) specimens no. 54000 50000 58000 58000 h-l 441) -(195 33 , 34 , 35 44200 43000 41600 48000 l-h 195) -(441 36 , 37 ,38 shot peening time -20 min 50000 50000 , 50000, 50000 h-l 441) -(195 39 , 40 , 41 46500 47000 , 46000 , 46500 l-h 195)-(441 42 , 43 , 44 30min-ot peening time hs 43000 , 4300038000 , 48000 h-l 441) -(195 7, 4 6, 4 54 54500 54000 , 55000 , 54500 l-h 195)-(441 48 , 49 , 50 reduction factor cycles 7 endurance limit at 10 equations condition 13% 62 mpa σf = 3982.5 nf -o.232 dry fatigue mpa 55 0.338 f=12931 n f σ corrosion fatigue nf av. nf cycles loading sequence (mpa) specimen no. 26500 22000, 25000 28000,31000 h-l 441) -(195 25 , 26 , 27 , 28 34750 45000 , 36000 , 29000 , 29000 l-h 195)-(441 29 , 30 , 31 , 32 )(2015 72 -65khwarizmi engineering journal, vol. 11, no. 1, p.p. -al alalkawi h.j.m 70 4.3. cumulative fatigue life improvement factor(cflif%) the percentage of cumulative fatigue life improvement factor can be calculated by the following equation (eq.1) [17] : cflif% = �� ��� �� ��.������ ����� ��.� � ��� �� ��.���� � × 100 …(1) where : nf (corr.+sp) =no. of cycles to failure at the interaction of corrosion fatigue with shot peening (sp) for two stress levels. nf( corr.) =no. of cycles to failure at corrosion environment for two stress levels . shows the cflif% results. (7) table table7 he interaction of corrosion fatigue with shot peeningresults of cflif% under t 30 min. 20 min. 10 min. shot peening time 441 -195 441 -195 441 -195 h (mpa)-l 195 -441 195 -441 195 -441 l (mpa)-h 4.53 5.85 6.53 %cflif 4.138 2.72 2.26 it can be noticed that the cflif% is positive and this means that sp treatments improved the cumulative corrosion-fatigue life of 1100 al alloy.in general shot peening had a noticeable effect on cumulative fatigue life ,see table(7).the process of shot peening affect on crack growth life by increasing the time to failure by a factor of ( 2 4 ) for the lower applied stresses or by a factor of (1.2 2.7) for the higher stress levels [18]. in the present work ,shot peening improved the corrosion-cumulative fatigue life by a factor of approximately (2). seong et al. [12] studied the effect of shot peening on the fatigue life of 7075-t6 using 3.5% nacl solution for one week to one year under room temperature .they concluded that the shot peening has superior effectiveness to increase the corrosion-fatigue life and improved the fatigue limit by 24% compared with corrosion fatigue limit . 5. conclusions from the current work on the interaction of cumulative corrosion-fatigue and shot peening process of 1100 al alloy, the following remarks can be derived : 1. constant fatigue life was significantly reduced under corrosive environment and the fatigue strength was reduced by a factor of 13%. 2. cflif% was found to be from (2 6). 3. shot peening improved the cumulative corrosion-fatigue life by a factor of about (2). 4. shot peening is a useful method for components working under corrosive environment. 6. references [1] y murakami; r o ritchie "comprehensive structural integrity: cyclic loading and fatigue" vol.4 , pp 345, elsevier pergamon, (2003) . [2] r.h.oskouei, r.n.ibrahim " restoring the tensile properties of pvd-tin coated al 7075 t6 using a post heat treatment" surface coating technology 205(15),pp39673973, (2011) . [3] peter george forrest , "fatigue of metals ", pp1,205 , pergamon press, (1962). [4] kiyoshi funatani ,lin xie ( handbook of metallurgy process design edited by george e.totten ) , crc press , pp 858 ,(2006). [5] f. menan and g. hénaff."synergistic action of fatigue and corrosion during crack growth in the 2024 aluminium alloy", procedia engineering, vol. 2, pp.1441-1450, (2010). [6] hussain j.m. alalkawi , qusay khalid mohammed, waleed sadun al-nuami "the effect of shot peening and residual stresses on cumulative fatigue damage" eng.& tech., vol.28, no.15,(2010). [7] y.k. gao "improvement of fatigue property in 7050–t7451 aluminum alloy by laser peening and shot peening" materials science and engineering: a , vol. 528, issues 10–11, pp 3823–3828 , (25 april 2011). )(2015 72 -65khwarizmi engineering journal, vol. 11, no. 1, p.p. -al alalkawi h.j.m 71 [8] li xu-dong, wang xi-shu, ren huai-hui, chen yin-long, mu zhi-tao."effect of prior corrosion state on the fatigue small cracking behavior of 6151-t6 aluminum alloy" , corrosion science, vol. 55,pp. 26–33, (2012). [9] f. p. ford "corrosion fatigue crack propagation in aluminum-7% magnesium alloy" science and engineering, vol. 35, no. 7, pp. 281-287, (july 1979. published online 2013). [10] a. laurino, e. andrieu, j.-p. harouard, g. odemer, j.-c. salabura, c. blanc "effect of corrosion on the fatigue life and fracture mechanisms of 6101 aluminum alloy wires for car manufacturing applications" materials & design ,vol. 53, pp 236–249 ,(january 2014) . [11] annual book of astm standards, (standard specification for aluminum and aluminumalloy sheet and plate), american society for testing and material, vol. 02.02,section2, pp298,(2009). [12] seong k.c,ji h.n.,hao h.l.,tao h.l., tae h.k." effects of shot peening on the corrosion fatigue life of al 7075-t6 ", icsp9:shot peening (2005). [13] p.s.pao, s.j.gill, c.r.feng, "on fatigue crack initiation from corrosion pits in 7075t7351 aluminum alloy" scripta materialia ,vol.43, pp.391-396, (2000). [14] k. genel. "the effect of pitting on the bending fatigue performance of high-strength aluminum alloy", scripta materialia, vol. 57, pp.297–300, (2007). [15] kimberli jones, david w.hoeppner" the interaction between pitting corrosion ,grain boundaries ,and constituent particles during corrosion fatigue of 7075-t6 aluminum alloy" int.j.fat. , vol.31 , pp 686-692 ,(2009). [16] miller,k.j. , mohamed h.j.alalkawi , de.los.rios,( fatigue damage accumulation above and below the fatigue limit )european group on fracture publication no.1, egfi , london ,(1986). [17] sharp p.k ,barter s.a, clark g." localized life extension specification for the f/a-18 y470 x19 pocket" ,melbourne:dsto-tn0279,(2000). [18] r.a.everett , w.t.matthews ,r.prabhakaran, j.c.newman, m. j. dubberly " the effects of shot and laser peening on fatigue life and crack growth in 2024 aluminum alloy and 4340 steel" nasa/tm (2001). ا�����وي��� )2015( 72 -65، ! �� 1ا���د، ���11 ا���ارز�� ا������� ا������ ��� 72 �3h12-1100ا45 �123& ا��0ل ا�.&ا,�� ا�.-,�� �+ ا�*(ف '���&%�ت ��#��� ا�����م ا�����وي��� ***ز��6 **�7' 8%86 9�%& ���� ���� *��� �� ا����و������� *�� �&'�� &ا�%��$� ا�#��/ "! ھ �� ا�*&اد ***،** ����/ "! ھ�� ا�%��$� ا�*!#�.�-� /,+�� ا�� alalkawi2012@yahoo.com :/ا��0#�و� � *ا��1amer.h.m.altaee@gmail.com :/ا��0#�و� � ** ا��1***� faithful_mind1990@yahoo.com: ا��0#�و�/ ا��1 �!0� ا� 6�ث ا��4ل ا�#�,+/ 2&-��gh��2ف ����2-�ت c d+c*� @�ا, ا��4ل @*b درا�� @?<�� ا�#.+��.ط� @?<�� ��,= �2> ا�6*; ا��وري وا�&�8 ا�7#,+/ @ ا'�اء .-&م "1; ا'�اء �q&6rت ا��4ل) ٧١(�*�ة ٣.٥nacl%@ j*� ا�$���ت 2*6+&ل -6#&ي h12-(1100 . �1!� d+c(ا�#7,+/ �!���1 ا�0*��&م ,��g @ ا'�اء �q&6rت @�ا, ا��4ل ا�#�,+/ ��wض ا-%�د اc*�ر ا�$���ت "1; و$2� c*+�� ا�ghف . �q&6rت ا��4ل <�2#� ا�!$� �u و 2�ون ا�&�8 ا�#�,+/ � �q&6rت ا�!$� ا��x2 bَ+" �#2�z. ����2-�ت �c ر ا��4ل�*c�1 ا!�و'� . ��hر�� �u ا��4ل ا�%�ف ١٣%; وا[\ �#�%� �+&�8 ا�#�,+/ وان ]� ا��4ل "َ; 2 @ ا�#&q; ا�d ان �h� . <!6@ ;��cر�� �c u*� @�ا, ا��4ل 2�ون c*+�� ا�ghف ) ٢(ان r/ ]��� ا�ghف ����2-�ت �rن c*� @�ا, ا��4ل ا�#�,+/ "َ; ��$2; .�#�%� �*$��+� ا�!gh��2 \dف ����2-�ت ) ٢-٦(@�اوح �� �2> ) %c _`q&2�1!� �-&a�)cflif*� ا��4ل ا�#�ا,*/ (microsoft word \321\324\30769-79) al-khwarizmi engineering journal al-khwarizmi engineering journal,vol. 13, no.4, p.p. 6979 (2017) the effect of walled nano-carbon on the physical, thermal and mechanical properties of epoxy rasha mohammed hussein department of mechanical engineering / university of technology email: mechanicalflower99@yahoo.com (received 2 january 2017; accepted 28 march 2017) https://doi.org/10.22153/kej.2017.03.006 abstract the physical, the thermal and the mechanical properties of nano-composites, that consisted of polyprime ep epoxy that reinforced by multi-walled carbon nanotubes (mwcnts), have been studied. various loading ratios, 0.1, 0.5, and 1 wt. %of mwcnt shave been infused into epoxy by a magnetic stirrer and then the hardener mixed with the mthat supplied with the epoxy. all sample shave been cutting using cnc machine. tensile test, three-point bending, hardness tests, lee's disk, differential scanning calorimetry, water absorption and dielectric and electrical conductivity test were utilized on unfilled, mwcnt-filled epoxy to identify the loading effect on the properties of materials. scanning electron microscopy (sem) was used to determine the dispersion case of nanotubes in the base matrix. the tensile test results showed an improvement in young’s modulus with higher mwcnt addition percentages. the highest value of the tensile strength was obtained at 0.5 wt.% of mwcnt with increasing ratio 66.7%. the values of the shore d hardness tests are slightly increases as the filler percentage increased, and the maximum value was observed at mwcnt weight percent of 4.4. images of sem showed that the specimen of 0.1 wt.% mwcnt has less voids as compared with other specimen. thermal conductivity and glass transition temperature increase when the loading ratio increased the maximum increasing at 1wt% with 120% and 23% respectively. the true density and electrical conductivity increase when nano carbon infused but decreasing in the dielectric constant and water absorber. keywords: multi-walled nano-carbon tube, (mwcnt)/epoxy composites, scanning electron microscopy 1. introduction the nanocomposites are kind of materials consist of dispenser inorganic nanomaterials into an organic polymer matrix, these nanomaterials improves the properties of the polymers. adding a small quantitative of inorganic materials such as carbon nanotubes (cnts), clay and metal nanoparticles, into the polymer matrix can considerably improving the performance of the polymer materials[1].numerous works were made for improving the properties of epoxy composites by the addition of fillers [2–3]. whereas, fillers addition enhancing the modulus of elasticity and ultimate strength of epoxy, but it decreases fracture toughness. recently, nano-fillers such as nanoparticles, nanotubes, nanofibers, and clay have been considered as good filler for made high performance epoxy nanocomposites with improved their properties [4–6]. carbon nanotubes are excellent nano-reinforcing filler that can be added to a variety of polymer matrices due to their properties; the ultimate tensile about 100 times higher than steel, its modulus of elasticity as high as1 tpa, its thermal conductivity is higher than diamond, their electrical capacity is 1000 times greater than copper, and thermally stable about2800°c in vacuum [7]. the researchers that worked on this subject showed that there are a diverse carbon nanotubes filler that could be mixed with various polymer matrices to form nanocomposites, e.g. polyamides rasha mohammed hussein al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 6979 (2017) 70 [8], polyimides [9], epoxy [10], polyurethane [11, 12] and polypropylene [13]. it is well documented that adding small amount of cnt (less than 1 wt.%) to a matrix system can significantly improve the thermal ,electrical and mechanical properties of those composites. the epoxy/mwcnt nanocomposites is a very vital research area and attracted many researchers, e.g. zhou et al. [4], liu et al. [14], sabarina than et al. [15], martone et al. [16], gouda et al.[17], and shokrieh et al. [18]. zhou et al. [4] studied the electrical, mechanical properties and thermal of mwcnts/epoxy nanocomposites. the cnts used were 0.1, 0.2, 0.3, and 0.4 wt. %, mixed with the epon 862matrix via a high intensity processor of ultrasonic liquid. good improvements were achieved, especially on electric conductivity. shokrieh et al. [18], studied a polyester/mwcnts nanocomposites at different carbon nanotubes loading ratios (0.05wt%, 0.1wt%, and 0.5 wt. %). sonication technique and mechanical stirring and were used to achieve well dispersion. their results exhibiteda good improvements of tensile strength and flexural strength by 6% and 20%, respectively, at the mwcnt loading ratio of 0.05 %. the effect of concurrent presence of multi walled carbon nanotubes and nano clay on the electrical and mechanical properties of an epoxy system was investigated using ultrasonic technique was studied by majid [19] jeena [20] presented result of the nanocomposites that contained epoxy and multi-walled carbonnanotubes (0% to 10 wt.%) and black carbon (0% to 15 wt%). the increasing in electrical and thermal conductivities, tensile strength, glass transition temperature and microhardness showed by using twin screw extruded. the purpose of the present paper was to study the effect of adding multi-walled carbon nanotubes (mwcnts) on the properties of epoxy/mwcnts nanocomposites. the mwcnts'sweight ratios are(0.05, 0.1, and 0.5 wt. %) were studied, all samples were prepared by using a magnetic stirrer and cutting by cnc machine. tensile tests, flexural tests, hardness tests (shore d),thermal conductivity test, differential scanning calorimetry test, water absorptionand electric and dielectric test, were performed to evaluate mechanical, thermal and physical performances. scanning electron microscopy (sem) was used to investigate the dispersion of nano carbon tubes in the epoxy matrix. 2. experimental work 2.1. materials processing the epoxy used was polyprime ep manufactured by henkel polybit industries ltd, provided with a hardener that used to achieve curing. the mixing percentage was 1/3 by weight of the epoxy resin. the density was 1.03 g/cc, initial cure at 25°c and 50% rh is 6-8 hours and application temperature is 10 to 35 °c. the multiwallednano carbon tubes (mwcnt) that used here (purity > 90%) was manufactured by the cheap tubes inc. (usa), as shown in figure 1. the tube diameter ranges from10 to 30 nm, the tube length ranges from 10 to 30μm. fig.1. tem image of mwcnts. three series of composites were prepared with different content of mwcnts as 0.1, 0.5 and 1 wt. % by magnetic stirrer shown in fig.2. a magnetic stirrer that used in this work employs a rotating magnetic fieldor a set of stationary electromagnets to make a stir bar that immersed in a liquid, to spin rapidly. a stir bar mixing a solution on a combined hot-plate magnetic-stirrer device. the mixing of epoxy and hardener initially made highly interactive, volatile vapor bubbles. therefore, the epoxy resin, in the magnetic stirrer, was preheated to 60°c to reduce its viscosity, thus reducing the chance of voids initiations and to provide good mixing with nanocarbon. then the mwcnts were added and mixed via stirrer bar for about 15 min to obtain homogeneity, then the hardener was added while the mixing process continue and mixing with them by wood rod for 5 min approximately. after the bubbles were totally removed, the mixture was transferred to glass molds with overhead paper to prevent adhesive for 24 hours at room temperature. 1.00um rasha mohammed hussein al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 6979 (2017) 71 fig.2. magnetic stirrer. 2.2. scanning electron microscope a scanning electron microscope (sem) is shown in fig. 3. for scanning the epoxy/mwcnts composites sem images at different magnifications are shown in figure 4 for different mwcnts ratios. it is shown from this figure that the nanocomposite with 0.1 wt.% carbon nanotubes has less voids. micro agglomeration particles and some voids, where pores are located at the agglomerates junctions. the dark and black regions correspond to the pores and nano carbon particles respectively, while the lighter areas are for epoxyphase. furthermore, it is clear that by increasing nano carbon, the porosity decreased because the agglomeration increase and denser materials obtained. if there were a crack, its propagation occurs near the voids in the microstructure. fig. 3. sem microscope (inspect s50) used. (a) (a) (b) nano carbon pore epoxy nano carbon epoxy pore nano carbon epoxy pore rasha mohammed hussein al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 6979 (2017) 72 (b) ( c ) (c ) fig. 4. sem pictures of epoxy/mwcnts nanocomposites at different weight ratio of mwcnts;(a)with 0.1wt.% mwcnts,(b)with 0.5wt.%mwcnts, and (c) with 1 wt.% mwcnts. 2.3 mechanical tests 2.3.1. tensile test tensile tests specimens were obtained using cnc machine, knuth rapimill 700. fourseries of specimens were prepared, three of them have mwcnts ratio of 0.1, 0.5, and1 wt.%, respectively, and the fourth one is a neat epoxy, the specimens’ dimensions were achieved according to astm d638, as in figure 5. the tensile tests were performed using a servohydraulic tinius olsen h50kt.all tests were performed at room temperature and crosshead speed of 5.0 mm/min. the tensile stress–strain curve can provide data on toughness, ultimate tensile strength, maximum elongation, and young’s modulus. the tests result for the four specimens is listed in table 1.stress-strain curve from tensile test are shown in fig.(6).the observed improvements may beattributed to the excellent dispersion of mwnt in resin phase and the better interphase orinterfacial bonding between resin and carbon fibers. (a) (b) fig. 5. tensile test specimens according to astm d638, (a) before tests, (b) fractured specimens. nano carbon pore epoxy nano carbon pore epoxy nano carbon pore epoxy rasha mohammed hussein al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 6979 (2017) 73 fig. 6. stress-strain behaviorsof mwcnt/epoxy nanocomposites with different mwcnt ratios. it is shown from table 1 that the young’s modulus slightly increases by 7% as the filler addition of the mwcnts increased maximum increasing young modulus is 26% when the wt% of nano-carbon is 1% depends on clusters size of nano-carbon and their distribution in the matrix. the ultimate strength results showed a maximum value of 30.448 mpa at 0.1 wt.% mwcnt addition, at this ratio a less voids were observed form the sem images (figure 4) performed in the present work. the maximum elongations obtained from the experimental results were decreased as the mwcnt values were increased because the formation of attractive polar forces, vander-waals bonding the nanotubes with chains leads to increase restriction between chains of epoxy andchains of nano-tubes/epoxy, will decrease free volume space and decreases the length of epoxy chains performed decreasing ultimate strength. table 1, mechanical property of epoxy /mwcnt nanocomposites. young’s modulus (gpa) ultimate strength (mpa) maximum elongation (%) neat epoxy 6.813 19.884 3.508 epoxy with 0.1 wt% mwcnt 7.299 30.448 3.128 epoxy with 0.5 wt% mwcnt 8.220 16.910 2.450 epoxy with 1.0 wt% mwcnt 8.564 20.996 1.248 2.3.2. bending test flexural tests were performed according to astmd790under a three-point bending. the tests were done using a servo-hydraulic testing machine, wdw-200 with speed of 5.0 mm/min. the results of the flexural tests are shown in figure 7 the maximum improvement in the flexural strength was obtained at the mwcnt ratio of 0.5 wt. % with has the maximum increasing percentage is 66.67% from pure epoxy. when the weight ratio of carbon increase to 1% the flexural strength decrease by 23.3% because the agglomerate increase that produced stress concentration point leads to the creatingthe fracture source. fig.7. flexural strength of mwcnt/epoxynanocomposites in various loading ratios. 2.3.3. hardness the hardness of material is an important mechanical property because it relates how much the material will inelastic deformed when a surface load is applied. in the present paper, the shore d hardness is used for measuring the hardness of the epoxy/mwcnt nanocomposites, the apparatus used is known as a durometer. the tests were performed according to astm d2240at room temperature and measured three times at different locations. the average value of three time testing have been recorded as the hardness value. the devise that used for measuring the hardness of the present paper is shown in figure fig.8.b, the results of the hardness tests are shown in fig. 8.a.the hardness test results revealed a relatively slight increase in the hardness test values, because adding the filler nano-particles will raise the materials hardness due to increasing in material resistance against the plastic deformation. the maximum one was obtained at mwcnt ratio of 0.1 wt. %. rasha mohammed hussein al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 6979 (2017) 74 increased hardness values due to stacking, which decrease the polymer's molecules movement, which lead to rise the resistance of material to scratch, cut and improving the resistance to the plastic deformation. hardness of material was depended on the kind of force that interconnected between particles in the material. (a) (b) fig. 8. (a) hardness shore d results for the nanocomposites with different mwcnt ratios, (b) hardness shore d devise used for this purpose. 2.4 thermal test 2.4.1. thermal conductivity test coefficient of thermal conductivity of all specimens was measured using lee’s disk method. very often composite materials results in anisotropic media and their thermal conductivity change along the axes because of the presences of reinforcing fibers embedded in the matrix. fig.9. represents the test apparatus (lee’s disk apparatus) with tested composite specimen and some accessories to measure the temperature of both sides of the composite specimen. the heater is switch on with (v = 6 volts and i = 2 amp.) to heat the brass disks (2,3). and the temperatures were recorded every (5 minutes) until reach to the equilibrium temperature of all disks. to measure the thermal conductivity using the lee’s disk method is in the form of a disk whose thickness d�is small relative to its radius (r) with (d� � d� � d� � 12.25 mm . �t�, t�, t� is the temperature of the brass disk. using a thin sample means that the system will reach thermal equilibrium more quickly. and the thermal conductivity can be calculated experimentally by using the following equation, [23]: k ∗ ������ �� � � e ∗ �t� � � � ∗ �d� � � � ∗ d�� ∗ t� � � � ∗ d� ∗ t�� ...(1) and (e) can be evaluated from the following equation, [23]: i ∗ v � π ∗ r� ∗ e ∗ �t� � t� � 2 ∗ π ∗ r ∗ e ∗ �d� ∗ t� � � � ∗ d� ∗ �t� � t� � d� ∗ t� � d� ∗ t�� ...(2) fig. 9. lee's disk apparatus. from fig. 10. the thermal conductivity coefficient increase when the weight ratio of nanocrabon is (1%) the maximum percentage of increasing is 120% because the nanocarbon tube has a very good thermal conductivity that cause increasing the thermal conductivity of polymer matrix. fig. 10. thermal conductivity coefficient results. rasha mohammed hussein al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 6979 (2017) 75 2.4.2. differential scanning calorimetry (dsc) differential scanning calorimetry is a thermoanalytical technique in which the difference in the amount of heat required to increase the temperature of a sample is measured as a function of temperature. glass transition temperature, tg, were obtained by using dsc (model sta pt-1000 linseis, temperature range: 0°c to 600°c) showed in fig. (11). a 20mg sample was used with range of temperature is from 23°c to 300°c with heating rate 5°c/min. to obtain the curing heat flow of the nano-composite. fig (12) shows the value of glass transition temperature which increasing with increasenano-carbon content in the composite. tgis the point at with the material goes from a hard brittle state to a soft rubbery state which increased with increase in mwcnt expect when weight ratio is 0.5% the tg is decrease with respect to 0.1% wt with percentage 8.1% because the dispersion of carbon nano tube. thea maximum of increasing was achieved with 1wt% loading is 23% with respect to pure matrix. the addition of nano carbon tube enhanced the thermal stability of thematerial, whichmay be because the decrease in the mobility of the chains of the epoxy around the nanofillers by strong interactions. fig. 11. differential scanning calorimetry device. fig. 12. glass transition temperatures, tg, results for the nanocomposites with different mwcnt ratios. 2.5. physical test 2.5.1 water absorption it is well known that the water absorption is the physical property upon that dopends on the water enters the open pore channel [21]. the mechanism of water absorption is explained to be the direct uptake and flow of water by capillary and transport along the reinforcement-matrix interface. water absorption percentage is calculated using [20] :( archimedes base) w.a %( the water absorption of the spacement) = $%�$� $� ∗ 100 ...(3) the water absorption of all prepared composites can be seen the specimen (pure epoxy) have higher water absorption than specimen (with nano filler), the decreasing water absorption percentage with increasing weight ratio of nanocarbon because the present nano carbon enclosed the porosity. the water absorption attacked the nono particle-matrix interface, causing de-bonding of the nano carbon and the matrix. the results shown in fig. 14. fig. 13. sensitive libra used (division 0.001g) with hang system. fig. 14. result of water absorber for the nanocomposites with different mwcnt ratios. rasha mohammed hussein al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 6979 (2017) 76 2.5.2 electrical and dielectrical test epoxy polymer has nature of insulating can cause garnering of electrostatic charge on their surface, causing premature degradation to the electronic structures. electrical and dielectrical constants of the samples were found according to astm d257 using lcr-8110g/8105g resistivity test fixture shown fig.15. the specimens were adhesive with tape of copper on two faces and two wires one for each face for better contact. the electrical properties of the nano carbon composites material depends on the shape and size of the nano carbon tube, the properties of epoxy matrix, method of manufacturing, dispersion of the nano carbonin matrix and interaction between component. the electrical percolation threshold is the minimal weight ratio of the nano materialsso that a remaining conductive network exists in the material. above this weight ratio, the electrical conductivity of the composite is very high. under the electrical percolation threshold, the composite material behaves as an insulator.[22] electrical conductivity is the ability of material to conduct the electrical current. g=ϭ*a/l ...(4) a dielectric material is an electrical insulator that can be polarized by an applied electric field is the reciprocal of electrical conductivity. when a dielectric is placed in an electric field, electric charges do not flow through the material as they do in a conductor, but only slightly shift from their average equilibrium positions causing dielectric polarization. c = ε r ε 0 a /d ...(5) in nanoscale capacitors, however, the electrostatic potentials experienced by electrons are determined by the number and locations of all electrons that contribute to the electronic properties of the device. in such devices, the number of electrons may be very small, however, the resulting spatial distribution of equilpotential surfaces within the device are exceedingly complex. the results shown in figs. (16,17) the electrical conductivity is increase when the loading ratio increased the maximum value of thermal conductivity obtained at wt is 1% because the percolation threshold were obtained i.e., the conductive network were built in the based (matrix) and electrons can be conducted also, the dielectric constant decrease when the loading ratio increase the pure epoxy gave the maximum dielectric constant. fig. 15. lcr-8110g/8105g resistivity test fixture. fig. 16. electrical conductivity's results for the nanocomposites with different mwcnt ratios. fig. 17. dielectrically constant's resultsfor the nanocomposites with different mwcnt ratios. 3. conclusion in this paper, the mechanical, thermal and physical properties of mwcnt/epoxy nanocomposites at different mwcnts weight ratios (0.1, 0.5, and 1 wt. %) were investigated. rasha mohammed hussein al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 6979 (2017) 77 the mwcnts were infused into epoxy through a magnetic stirrer and then mixed with the hardener that supplied with the epoxy. it is shown that the dispersion of multi-walled nanotubes in the epoxy is greatly influences the results of mechanical tests. sem images were used to distinguish the dispersion state of nanotubes in the matrix. the trend of results shows that adding low weight fractions of mwcnt improves tensile and flexural properties of the nanocomposites that the maximum improvement in the flexural strength was obtained at the mwcnt ratio of 0.5 wt. % with has the maximum increasing percentage is 66.67%,however, more increase in mwcnt weight fraction may causes reduction in mechanical properties. improvements in young’s modulus were observed with a higher mwcnt weight percent. the best amounts of filler for the best properties for tensile strength and flexural strength occur at 0.1 and 0.5 wt. %, respectively. the maximum elongations values were decreased with the increases of mwcnts weight ratios. the hardness test results did not change significantly. the decrease in mechanical properties were attributed to poor dispersions of the carbon nanotubes in the composite. . thermal conductivity and glass transition temperature increase when the loading ratio increased the maximum increasing at 1wt% with 120% and 23% respectively. the electrical conductivity increase when nano carbon infused but decreasing in the dielectric constant and water absorber. notation a the cross-sectional area (m²) c the capacitance, in farads d the separation between the plates, in meters; g electrical conductance (siemens) l the length of the conductor (m), '� dry sample weight (g). 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[21] fadhil a. chyad, mohammed s. hamza, zainab i. dhary, “physical and mechanical properties of synthesized doped nanoferrite”al-khwarizmi engineering journal , vol. 12, no. 2, p.p. 1017 (2016) [22] jeena jose karippal, narasimha murthy h. n.,.rai k. s, krishna m., andsreejith m.,” the processing and characterization of mwcnt/epoxy and cb/epoxy nanocomposites using twin screw extrusion” , polymer-plastics technology and engineering, 49: 1207–1213, 2010 [23] louay s. yousouf, “time prediction of dynamic behavior of glass fiber reinforced polyester composites subjected to fluctuating varied temperatures” al-khwarizmi engineering journal, vol5, no3,pp2837(2009). )2017( 69-79، صفحة 4د، العد13دجلة الخوارزمي الهندسية المجلم رشا محمد حسين 79 الى نيكيةاثير اضافة كاربون نانوي متعدد الجدران على الخواص الفيزيائية والحرارية والميكات الراتنج االيبوكسي رشا محمد حسين التكنولوجية الجامعة/ الميكانيكية الهندسة قسم mechanicalflower99@yahoo.com :البريد االلكتروني الخالصة الخلط عملية تمت .االيبوكسي ومادة الجدران متعدد نانوي كاربون من المتكونة النانوية للمركبات الميكانيكيةالفيزيائية والحرارية و الخصائص دراسة تم اجراء تم. المصلد إضافة تمت ثم ومن االيبوكسي، الى ,%0.5 ,%1) ٠٫١% (يونالنانو للكارب مختلفة وزنية نسب بإضافة مغناطيسي خالط طةسابو المصنعة العينات لجميعالموصلية الحرارية والمسعر الحراري التبايني وامتصاص الماء والعزل والتوصيل الكهربائي و والصالدة واالنحناء الشد اختبارات النانوي للكاربون التشتت حالة لدراسة اإللكتروني المجهر ستخدام ا تم). إضافة يةا بدون االيبوكسي من المصنوعة وتلك النانوي الكاربون على تحتوي التي( في( األقصى جهاداالتم الحصول على الكاربون نسبة زيادة مع مرونةال لمعامل ناتحس هنالك ان الميكانيكية لالختبارات النتائج أظهرت. النانوي المركب في . الصالدة في %٤٫٤ بحدود بسيطة وزيادة ،%٦٦٫٧بنسبة زيادة %٠٫٥عند نسبة )النحناءاختبارا ان .األخرى النسب مع بالمقارنة % ٠٫١ البالغة النانوي للكاربون الوزنية النسبة مالحظتهاعند تم للفجوات نسبة اقل ان أظهرتصورالمجهراإللكتروني %١الوزنية معامل التوصيل الحراري ودرجة حرارة التحول الزجاجي تزداد عند زيادة نسبة الكاربون النانوي المضاف حيث تصل نسبة الزيادة عند النسبة الكهربائية وقابلية على التوالي. في حين ان الموصلية الكهربائية تزداد عند زيادة نسبة الكاربون النانوي على عكس ثابت العزل %٢٣و %١٢٠الى امتصاص الماء سوف تقل عند زيادة النسبة. al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 31-44 (2015) study on flow characteristics and heat transfer behavior around different geometrical corrugated extended surfaces naseer abdul razzaq mousa engineering affaire department/ university of baghdad email: nasseer64@gmail.com (received 16 march 2014; accepted 15 december 2014) abstract the current study presents numerical investigation of the fluid (air) flow characteristics and convection heat transfer around different corrugated surfaces geometry in the low reynolds number region (re<1000). the geometries are included wavy, triangle, and rectangular. the effect of different geometry parameters such as aspect ratio and number of cycles per unit length on flow field characteristics and heat transfer was estimated and compared with each other. the computerized fluid dynamics package (ansys 14) is used to simulate the flow field and heat transfer, solve the governing equations, and extract the results. it is found that the turbulence intensity for rectangular extended surface was larger than that of triangle and wavy extended surfaces at the same aspect ratio and number of cycles per unit length. also, the increasing of turbulence intensity leads to enhance the heat transfer coefficient and consequently the amount of heat transfer. according to previous results, if the pressure head losses along the upstream are not important, the using of rectangular extended surface is better than the triangle which is also better than wavy extended surface. keywords: flow characteristics, heat transfer, corrugated surfaces, numerical analysis by ansys. 1. introduction the enhancement of heat transfer is required in wide engineering applications. two groups of heat transfer enhancements techniques have been identified: “passive” and “active” techniques. passive techniques use special surface geometries, or fluid additives for heat transfer enhancement, such as coated surfaces, extended surfaces, rough surfaces, swirl flow devices, surface tension devices, and additives for liquids or gases. the active techniques require external power, such as electric or acoustic fields and surface vibration [1]. extended surfaces (fins) are widely used for many engineering applications such as heat exchangers. the extended surface improves the heat transfer coefficient by altering the flow field besides increasing the effective heat transfer surface area [2]. examples of such fins include corrugated or wavy fins shown in figure 1. fig. 1. examples of corrugated extended surface [1]. the use of specially configured surfaces (such as fins) can provide the improved heat transfer coefficient and increased effective heat transfer surface area, and reduce the gas-side thermal resistance [ .[3due to small characteristic length (wave length) of extended surfaces and the low density of gas, special surface geometries must be effective in the low reynolds number region [re <1000]. focke et al. [4] conducted flow visualization experimental studies in channels with wavy walls formed in a plate heat exchanger. in their study, the complex flow patterns in flow rate of re = 10 to 1000 were reported. for the channel with mailto:nasseer64@gmail.com naseer abdul razzaq al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 3144 (2015) 32 corrugation 90°, they found that the main flow was undulating in the direction of channel axis, and at low flow rate no flow separation was observed; flow separation first took place at re = 20, and with the increase of re, the separated region increases in size, the flow became unsteady after re ~ 260. nishimura et al. [5] have investigated experimentally the flow pattern and mass transfer characteristics in symmetric wavywalled channels at moderate reynolds numbers (re = 20–300). they concluded that the characteristics of mass transfer for wavy-walled channels differ from those of a straight-walled channel when flow separation takes place. nishimura et al. (6) also experimentally investigated the longitudinal vortices generation, growth, and destruction in various wavy flow channels. secondary flow characteristics were also reported. the authors believed that secondary flow played an important role to enhance the mass and heat transfer. ali and ramadhyani [7] conducted an experimental study on grooved (corrugated) channels of planner cross section in the steady and transitional reynolds number regimes (150 < re < 4,000). their studies indicated the formation of longitudinal vortices which increased in size with increase in reynolds number. in addition, spanwise vortices appeared from the shear layers to transfer near-wall fluid to the core area and enhance heat transfer rate. performance evaluation indicated that wavy channels give better rates of heat transfer when operated at transitional reynolds numbers. the fluid flow and heat transfer through a periodic array of sinusoidal-shaped channels were studied numerically by wang and vanka [8]. in their study, the flow was observed to be steady up to re =180, after which self-sustained oscillatory flow was noticed. in the transitional flow regime, the heat transfer enhancement ratios were more than twice those of a parallel-plate channel, but were accompanied by a higher friction factor. stone and vanka [9] studied the developing flow and heat transfer in a wavy passage using a numerical scheme that solves the two-dimensional unsteady flow and energy equations. their calculations were presented for a wavy channel consisting of 14 modules with a fixed set of geometric parameters. consideration was given to sinusoidal channels only. niceno and nobile [10] studied the flow characteristics in both arc-shaped and sinusoidal wavy channels, employing an unstructured co-volume method. their results were limited to one set of geometric parameters. the current study numerically investigates the fluid flow and enhanced convection heat transfer in different extended geometry in the low reynolds number region [re <1000]. the geometries are included wavy, triangle, and rectangular. the effect of different geometry parameters on flow field characteristics and heat transfer coefficient was estimated and compared with each other. the computerized fluid dynamics package (ansys 14) is used to simulate the flow field and heat transfer, solve the governing equations, and extract the results. 2. geometrical description three shapes of corrugated surfaces with related geometrical parameters are taken into account in current study. the effects of these parameters on flow field and heat transfer coefficient are estimated numerically. these geometries and their related parameters are: 2.1. wave extended surface fig. 2. wave extended surface. fig. 3. geometrical description of wave extended surface where (aw) is the wave amplitude, (lw) is the wave length of wavy surface, λw is the aspect ratio of the wavy surface (λw=aw/lw), and (nw) is the number of waves per unit length (nw=1/lw). naseer abdul razzaq al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 3144 (2015) 33 2.2. triangular extended surface fig. 4. triangular extended surface. fig. 5. geometrical description of triangular extended surface. where (at) is the amplitude, (lt) is the pitch of triangle, (λt) is the aspect ratio of the triangular extended surface (λt = at/lt), and n is the number of triangles per unit length (nt=1/lt). 2.3. rectangular extended surface fig. 6. rectangular extended surface. fig. 7. geometrical description of rectangular extended surface. where (ar) is the amplitude of rectangular circle, (lr) is the pitch of the rectangle, (λr) is the aspect ratio of rectangular extended surface (λr= ar/lr), and n is the number of rectangular circles per unit length (nr=1/lr). 3. numerical simulation the aim of this simulation is to setting up and solving a conjugate heat transfer problem using ansys fluent 14. the geometry and flow domain consists of a corrugated surface with a heat generating source. heat is conducted through the source and the corrugated surface. a laminar stream of air flows over the corrugated surface, causing simultaneous cooling of the corrugated surface and heating of the air stream due to convection. the numerical simulation steps consist of three steps as shown in figure (8). the simulation began from preprocessing stage which included geometry setup, grid generation and boundary condition setup. the geometry of the model, the grid generation and boundary conditions setup was done by using software package (gambit 2.4.6.). after that, the complete model (geometry and mesh) was exported from gambit 2.4.6) to the (ansys fluent) software. the second stage was the computational simulation which done by using software package (ansys fluent) solver. finally is the post-processing stage where the results were found. fig. 8. numerical simulation stages. for flow simulating, the unstructured tetrahedral mesh was used. in unstructured approach, the integral form of governing equations is discretized and either a finite-volume or finite-element scheme is used. unstructured grids are in general successful for complex geometries [11]. volume mesh was created by using t-grid, gambit scheme. size functions are used to control the size of mesh interval for edges and mesh elements for faces or volumes and thus to keep smooth transition of mesh from fine mesh naseer abdul razzaq al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 3144 (2015) 34 near the faces to coarse mesh far away at the undistributed boundaries [12]. after the meshing process, the mesh was checked. it was to check on the quality of the mesh by observing the skewness level and abrupt changes in cell sizes. figures 9, 10, 11 show the mesh density around the wavy, triangular, and rectangular extended surfaces respectively. also, figure 12 shows the mesh inspection around wavy, triangular, and rectangular extended surface. fig. 9. mesh density around wave extended surface. fig. 10. mesh density around triangular extended surface. naseer abdul razzaq al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 3144 (2015) 35 fig. 11. mesh density around triangular extended surface. fig. 12. mesh inspection around wavy, triangular, and rectangular extended surface. 4. governing equations in current simulation, the governing equation for fluid flow and heat transfer are established. the governing equations to be considered are continuity, momentum and energy equation. turbulent flow and convective heat transfer prevail. steady state and constant thermo-physical proprieties are assumed. the three dimensional governing equations in cartesian coordinates can be expressed as [1]: 4.1. continuity equation ∂u ∂x + ∂v ∂y + ∂w ∂z = 0 …(1) 4.2. momentum equation 𝑢 𝜕𝑢 𝜕𝑥 + 𝑣 𝜕𝑢 𝜕𝑦 + 𝑤 𝜕𝑢 𝜕𝑧 = − 1 𝜌 𝜕𝑝 𝜕𝑥 + 𝑉 𝜕2𝑢 𝜕𝑥2 + 𝜕2𝑢 𝜕𝑦2 + 𝜕2𝑢 𝜕𝑧2 𝑢 𝜕𝑢 𝜕𝑥 + 𝑣 𝜕𝑢 𝜕𝑦 + 𝑤 𝜕𝑢 𝜕𝑧 = − 1 𝜌 𝜕𝑝 𝜕𝑦 + 𝑉 𝜕2𝑣 𝜕𝑥2 + 𝜕2𝑣 𝜕𝑦2 + 𝜕2𝑣 𝜕𝑧2 𝑢 𝜕𝑢 𝜕𝑥 + 𝑣 𝜕𝑢 𝜕𝑦 + 𝑤 𝜕𝑢 𝜕𝑧 = − 1 𝜌 𝜕𝑝 𝜕𝑧 + 𝑉 𝜕2𝑤 𝜕𝑥2 + 𝜕2𝑤 𝜕𝑦2 + 𝜕2𝑤 𝜕𝑧2 …(2) 4.3. energy equation 𝑢 𝜕𝑇 𝜕𝑥 + 𝑣 𝜕𝑇 𝜕𝑦 + 𝑤 𝜕𝑇 𝜕𝑧 = 𝑘 𝜌𝑐𝑝 𝜕2𝑇 𝜕𝑥2 + 𝜕2𝑇 𝜕𝑦2 + 𝜕2𝑇 𝜕𝑧2 ...(3) naseer abdul razzaq al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 3144 (2015) 36 5. boundary conditions inlet. a uniform inlet velocity profile was assigned at the inlet boundary condition (u = uin). the range of velocity (1-10m/s) is examined in current simulation because it mostly used in practical applications. wall. on the corrugated wall, the velocity fields meet no-slip wall boundary condition: u = v = w = 0 …(4) outlet. zero gage pressure at domain outlet was established. this means that the outlet open to the atmosphere. symmetry. symmetry boundary conditions are used when the physical geometry of interest and the expected pattern of the flow solution have mirror symmetry. also the symmetry boundaries are used to reduce the extent of computational model to a symmetric subsection of the overall physical system. all symmetric boundaries are assumed to be insulated. [13] thermal conditions. a constant inlet temperature (t = tin = 24c̊) was assigned at the channel inlet. 6. expressions for dimensionles parameters two significant dimensionless parameters help to quantify and evaluate the flow and heat transfer characteristics of the extended surface. these are: reynolds number, nusselt number and prandtl number. [14] 6.1. reynolds number (re) for the developing flow simulations, a uniform velocity profile is prescribed at the domain inlet, so the reynolds number is known in advance to be: re = ρul μ …(5) where (l) is the characteristic length of the wave length or pitch length to extended surfaces, the characteristic length is always very small especially when used in cooling circuits of electronic devices such as the cooling circuit of central processing unit of personal computers. in current study, this length is taken to be around 1.5 mm. typical calculations of the range of reynolds number used in current study are shown in appendix 1. 6.2. nusselt number (nu) the local nusselt number is defined as: nu = hl k …(6) 6.3. prandtl number (pr) the prandtl number is defined as: pr = μ cp k …(7) 7. simulation domain figure 13 shows the simulation domain. the heat generator (heat source) located at the corrugated surface. the heat transferred through the corrugated surface to the fluid (air) by forced convection. the stream of air enters the domain at specific temperature at entrance and leaves the domain from exit side. as a result of heat transfer, the temperature of air will increase. for simply, the wall of the domain and upper plane are assumed to be insulated to ensure that all heat generated by heat source will transferred to the air only and no heat losses from side wall and upper plane. the corrugated surfaces used are wavy, triangular, and rectangular. for this simulation, model air as an incompressible gas because there is air temperature rise but very little pressure change. the goal is to specify the effect of geometry of corrugated extended surface on heat transfer coefficient and heat transfer enhancement. the effects of geometrical parameters on flow characteristics, heat transfer behavior, and temperature distribution are investigated and analyzed. the flow characteristics included velocity distribution, pressure distribution, and turbulence intensity. fig. 13. simulation domain. naseer abdul razzaq al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 3144 (2015) 37 7.1. simulation validation the present numerical method is validated by comparison the predicted results of simple case with the corresponding theoretical solutions provided by reference [14] of average heat transfer coefficient (h) the simple case included air moving and warmed by isothermal steam heated plate. the exact theoretical solution was provided by reference [14]. the similar simulation of current study is used to evaluate the heat transfer coefficient h. the detailed is comparison between the theoretical and numerical results are shown in appendix 2. 7.2. calculation average convection heat transfer coefficient (𝐡 ) the calculation of average heat transfer coefficient by convection is done by using the classical equation of heat transfer by convection. 𝑞 = ℎ 𝐴 (𝑇𝑤 − 𝑇ave) …(8) where (a) is the area of corrugated surface, (tw) is the temperature of the corrugated surface and (tave) is the average temperature of air through the domain. in current simulation, we suppose the same amount of heat transferred (q) and the same temperature (tw) for all types of corrugated surfaces. the high value of average heat transfer coefficient leads to high leaving temperature (tout) of air according to equation of heat transfer by convection. the average heat transfer coefficient by convection is calculated because this coefficient is changing locally due to changing the flow behavior along the corrugated surface. 7.3. turbulence model the flow conditions were chosen to ensure laminar flow to distinguish the flow disturbance due to geometry of corrugated extended surfaces. this disturbance in flow near the surfaces will change the pattern of flow and increases the turbulence. so, the suitable turbulence model for current simulation should be chosen. the k-ε model is chosen for current simulation to estimate the turbulence intensity. the standard (k –ε) model is a semi-empirical model based on model transport equations for the turbulence kinetic energy k and its dissipation rate ε. this model is more suitable for complex geometries. [13] 8. result and discussion the first part of results concerns the effect of geometrical parameters (λ and n) on flow characteristics. figures 14, 15, and 16 are show the velocity distribution around the wavy, triangular, and rectangular extended surfaces respectively. these figures show complex flow pattern around these surfaces. the complex flow pattern is characterized by recirculation with periodic flow separation and reattachment. it is found that this flow pattern is very dependent to geometrical parameters (λ and n). fig. 14. velocity distribution around wavy extended surface. fig. 15. velocity distribution around triangular extended surface. fig. 16. velocity distribution around rectangular extended surface. naseer abdul razzaq al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 3144 (2015) 38 the range of (λ) considered in current study is (0.1-1) with pitch 0.1 while the range of (n) is (310) with pitch 1. at λ = 0.1, the recirculation regions are small. for wavy surface, the increasing of (λ) leads to increasing the volume of the recirculation regions until the value of (λ) reaches 0.6 but beyond this value of (λ) the increasing of the volume of recirculation regions is not significant. this observation is noted also for triangular and rectangular extended surface but the value of (λ) beyond which the increasing of volume of recirculation regions become not remarkable is not same. this value is 3.5 for triangular surface and 5 for rectangular surface. the increasing of (n) has more effect on the recirculation pattern than the increasing of (λ). the increasing of the number of cycles of corrugated surfaces per unit length leads to increasing the number of recirculation regions and leads to periodic flow separation and reattachment. the increasing of the number of circulation regions and the volume of these regions leads to increase the turbulence intensity around the corrugated surface significantly. the turbulence intensity affects the heat transfer behavior. figures 17, 18, and 19 are showing the turbulence intensity around the corrugated surfaces when the flow stream velocity was (1.5 m/s) and aspect ratio (λ = 1) for all types of corrugated surface. the first observation on these figures was that the values of turbulence intensity around the corrugated surfaces were close to each other but the difference was in the extension of the turbulence regions. the extension of turbulence regions around rectangular extended surface is larger than that of triangular extended surface which is also larger than that of the wavy extended surface. fig. 17. the turbulence intensity around the wavy extended surface. this result can be attributed to geometrical effect. the wavy surface is more streamlined body than the triangle and rectangle surface. the flow pattern around bluff body is more complex than that around streamlined body. the second observation from these figures is the presence of strong gradient in turbulence intensity values where the small value of the turbulence intensity noted near the corrugated surfaces and this value will increase away from surfaces to reach its maximum value and then decreases to lower value where the effect of corrugated surfaces will vanished. the changing of aspect ratio (λ) of any corrugated surface will affect the value of turbulence intensity around the corrugated surfaces. figure 20 shows the value of turbulence intensity at specific point near the corrugated surfaces versus the aspect ratio (λ). it is clear that the turbulence intensity increases when λ increased. the increasing of turbulence intensity versus the aspect ratio (λ) is remarkable until the aspect ratio reaches to specific value beyond which the increasing of turbulence intensity becomes very small. fig. 18. the turbulence intensity around the triangular extended surface fig. 19. the turbulence intensity around the rectangular extended surface. naseer abdul razzaq al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 3144 (2015) 39 these specific values are differing according to type of corrugated surface. these specific values are shown in figure 20. also, it is clear from figure 20 that the values of turbulence intensity for rectangular extended surface are larger than the values of turbulence intensity of triangular and wavy extended surface at the same flow stream velocity and the number of pitch per unit length. this result confirms the previous obtained result. figure 21 show the values of turbulence intensity versus the number of pitches per unit length (n) for all types of corrugated surfaces. it is clear from this figure that the turbulence intensity increases when the number of pitch per unit length increases. at specific point, the increasing in turbulence intensity due to increasing the number of pitch per unit length (n) is very small in comparison with the increasing of turbulence intensity due to increasing the aspect ratio as mentioned because the increasing the number of pitch per unit length (n) leads to increase the number of recirculation regions as first and then the turbulence intensity as whole. also, it is obvious from figure 21 that at specific point, the behavior of increment in turbulence intensity was approximately identical for all types of corrugated surfaces. fig. 20. turbulence intensity versus aspect ratio (λ) for all types of corrugated surface at flow stream velocity 7 m/s and pitch per unit length (n=3). fig. 21. turbulence intensity versus number of pitch per unit length n at flow stream velocity 7m/s and aspect ratio (λ=1). it is clear that the flow pattern around the corrugated surface characterized by strong flow mixing, periodic generation of vortices or recirculating regions. this flow pattern associated with pressure drop penalty. figures 22, 23, and 24 are showing the pressure distribution around the corrugated extended surfaces when the flow velocity was 10 m/s and aspect ratio was 0.8 for all types of surfaces. it is shown from these figures that there is a significant decreasing in dynamic pressure along the corrugated surface. the decreasing in dynamic pressure was concentrated near the corrugated wall and continuous along the corrugated surface. the pressure increases gradually away from corrugated wall. the decreasing pressure extended to vicinity area of corrugated surface. these vicinity areas were differ in size according to shape of corrugated surface. fig. 22. dynamic pressure distribution around the wavy extended surface at flow velocity 10m/s and aspect ratio 0.8. naseer abdul razzaq al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 3144 (2015) 40 fig. 23. dynamic pressure distribution around triangle extended surface at flow velocity 10m/s and aspect ratio 0.8. fig. 24. dynamic pressure distribution around rectangle extended surface at flow velocity 10m/s and aspect ratio 0.8. the size of this area around the triangle extended surface was larger than this around the rectangle extended surface. also, the size of this area around the rectangle extended surface was larger than this around the wavy extended surface. according to this result, if the pressure is an important issue, the sing of wavy extended surface is better than the rectangle corrugated surface and then the triangle surface. 8.1. heat transfer result the effect of flow characteristics around extended surfaces on heat transfer behavior are investigated numerically. all extended surface used in this simulation has the same number of cycles (3) and the same aspect ratio. the fluid domain has the same length for all types of extended surface. the depths of extended surface were changed to get the same area of all extended surfaces. figures 25, 26, and 27 are showing the temperature distribution along the fluid domain above the extended surfaces at (re = 964.577). fig. 25. temperature distribution along fluid domain above wavy extended surface at (re=964.577). fig. 26. temperature distribution along fluid domain above triangle extended surface at (re=964.577). fig. 27. temperature distribution along fluid domain above rectangular extended surface at (re=964.577). it is clear from these figures that the amount of heat transferred to fluid domain across the rectangular extended surface was larger than that of triangle surface and the amount of heat transferred across the triangle extended surface was larger than that of wavy surface. this conclusion was established because the value of naseer abdul razzaq al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 3144 (2015) 41 temperature of air at the outlet section above the rectangular extended surface was larger than that of triangle surface which also larger than that of wavy extended surface. this observation indicates that the flow behavior around the extended surface affected the heat transfer. also it is clear that the value of heat transfer coefficient was affected by flow behavior because that in current simulation we established the same transferring area, the amount of heat transferred, the same temperature difference between the extended surface and inlet air. also, this observation indicates that increasing of turbulence intensity leads to increasing in the amount of heat transferred. in other words, the increasing of turbulence intensity leads to enhance the coefficient of heat transfer. according to this result, the changing in any geometrical parameters which leads to increase the turbulence intensity will leads to enhance the coefficient of heat transfer. figure 28 show the values of average heat transfer coefficients versus the reynolds number for all types of corrugated surface. fig. 28. average heat transfer coefficient versus re for all corrugated extended surfaces it is clear from this figure that the above result (the amount of heat transferred to fluid domain across the rectangular extended surface was larger than that of triangle surface and the amount of heat transferred across the triangle extended surface was larger than that of wavy surface) was established for all values of reynolds number examined in current simulation. also, it is clear from figure 28 that the values of heat transfer coefficients for all three corrugated surfaces becomes close to each other at high values of reynolds. figure 28 can easily transformed to illustrate the relation between nusslet number versus reynolds number for all corrugated surface examined in current study by using relation (6) as in figure 29. fig. 29. nusslet number versus re for all corrugated extended surfaces. 9. conclusions 1the increasing of aspect ratio (λ) leads to increasing the volume of the recirculation regions until the value of (λ) reaches to specific value for each type of corrugated surface and beyond this value of (λ) the increasing of the volume of recirculation regions is not significant. these specific values are 0.6 for wavy, 0.35 for triangle and 5 for rectangular extended surface. 2the increasing of number of cycles per unit length (n) has more effect on recirculation pattern and turbulence intensity than the increasing of aspect ratio (λ). 3the turbulence intensity for rectangular extended surface was larger than that of wavy and triangle extended surfaces at the same aspect ratio and number of cycles. 4the increasing of turbulence intensity leads to enhance the heat transfer coefficient and consequently the amount of heat transfer. 5the heat transfer enhancement for rectangular extended surface was larger than triangle extended surface which also larger than that of wavy extended surface. 6according to previous results, if the pressure losses are not important, the using of rectangular extended surface is better than the triangle which is also better than wavy extended surface. naseer abdul razzaq al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 3144 (2015) 42 notation aw, at, ar wave amplitude of wavy, triangular, and rectangular extended surfaces respectively. [m] lw, lt, lr wave length of wavy, triangular, and rectangular extended surfaces respectively. [m] n generalized number of cycles per unit length. [cycle] nw, nt, nr number of cycles surface per unit length of wavy, triangular, and rectangular extended surfaces respectively. [dimensionless parameter] u, v, w the velocity components in coordinates directions x, y, z respectively. [m/s] p pressure [n/m2] ρ fluid density [kg/m3] k thermal conductivity [w/m.k] h heat transfer coefficient [ w/m2.k] cp, cv specific heat of fluid at constant pressure and constant volume respectively. [j/kg.k] t temperature. [k] re generalized reynolds number. [dimensionless parameter] nu nusselt number. [dimensionless parameter] pr prandtl number. [dimensionless parameter] greek letters λ generalized aspect ratio [dimensionless parameter] λw, λt, λr aspect ratio of wavy, triangular, and rectangular extended surfaces respectively. [dimensionless parameter] µ dynamic viscosity. [ kg/m.s] 10. references [1] jiehai z., "numerical simulations of steady low-reynolds-number flows and enhanced heat transfer in wavy plate-fin", university of cincinnati, 2004. [2] haitham m. s. and n. k. anand, " numerical study of heat and momentum transfer in channels with wavy walls", numerical heat transfer, part a, 47: 417– 439, 2005 [3] webb, r. l. “principles of enhanced heat transfer”, john wiley & sons, inc. new york, ny, 1994. [4] focke, w. w., and knibbe, p. g., “flow visualization in parallel-plate ducts with corrugated walls,” j. of fluid mechanics, vol. 165, 73-77, 1986. [5] nishimura t., murakami s., arakawa s., and kawamura y., flow observation and mass transfer characteristics in symmetrical wavy-walled channels at moderate reynolds numbers for steady flow, int. j. heat mass transfer, vol. 33, pp. 835–845, 1990. [6] nishimura t., yano k., yoshino t., and kawamura y., “occurrence and structure of taylorgoertler vortices induced in twodimensional wavy channels for steady flow,” j. of chem. eng. of japan, vol.23, no.6, pp. 697-703, 1990. [7] ali m. m. and ramadhyani s., experiments on convective heat transfer in corrugated channels. exp. heat transfer, vol. 5, pp. 175–193, 1992. [8] wang g. and vanka s. p., convective heat transfer in wavy passage, int. j. heat mass transfer, vol. 38, pp. 3219–3230, 1995. [9] stone k. and vanka s. p., numerical study of developing flow and heat transfer in a wavy passage. j. fluid eng., vol. 121, pp. 713–719, 1999. [10] niceno b. and nobile e., numerical analysis of fluid flow and heat transfer in periodic wavy channel, int. j. heat fluid flow, vol. 22, pp. 156–167, 2001. [11] hanaa a. h. “numerical and experimental investigation on the effect of restriction shape on characteristics of airflow in a square duct” ph.d thesis,mech. eng. dept., univ. of technology, 2006. [12] hamad h. h. "dynamic response of solar concentrating power system for self cleaning", ph.d thesis, university of technology, 2012. [13] ansys fluent reference theory. twelve edition, 2009. www.ansys.com [14] john h. l. " a heat transfer textbook", third edition, phlogiston press, cambridge, massachusetts, 2005 naseer abdul razzaq al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 3144 (2015) 43 appendix 1 reynolds number calculations in current simulation , the air enters to fluid domain at temperature 24c̊. the density of air at 24c̊ = 1.18 kg/m3 and dynamic viscosity at 24c̊ = 1.835*10-5 n.s/m2 table 1 reynolds number calculations. velocity(m/s) re 1 96.457 2 192.915 3 289.373 4 385.831 5 482.288 6 578.746 7 675.204 8 771.662 9 868.119 10 964.577 appendix 2 the validation of numerical simulation is done by comparison the theoretical results of simple case of convection heat transfer between heated simple geometry plate and moving air. the exact solution of this problem is presented in pages 308309 of reference [14]. the exact formula of average heat transfer coefficient of this problem is: ℎ = 0.664 𝑅𝑒 1 2 𝑃𝑟 1 3 𝑘 𝑙 where pr = 0.707, k = 0.02885 , l=0.5 ( according to problem conditions) [14]. the similar simulation domain of current study is used to evaluate the average heat transfer coefficient h with exception of geometry of plate as shown in figure (e1.1). fig. e1.1. average heat transfer coefficient h with exception of geometry of plate. the table 2 and figure e1.2 below show the values of average heat transfer coefficient obtained by numerical and theoretical solution at different values of reynolds number. fig. e1.2. average heat transfer coefficient h of reynolds number re. table 2 average heat transfer coefficient h. velocity (m/s) re h (theoretical solution) h (numerical solution) error percentage % 5 128865 12.252 10.567 13.75 7.5 193299 15 13.87 7.533 10 257732 17.327 15.23 12.1 12.5 322165 19.372 18.13 6.4 15 386598 21.221 19.54 7.92 (2015)3144 ، صفحة 2العدد ،11دالخوارزمي الهندسية المجلجلة م نصير عبد الرزاق 44 مختلفت هنذسيت اشكال راث متموجت سطوح حول الحرارة وانتقال الجريان خصائص دراست نصير عبذالرزاق موسى خايعت بغذاد/ قسى انشؤوٌ انهُذسُت nasseer64@gmail.com: انبشَذ االنكخشوٍَ الخالصت يخخهفت هُذسُت اشكال راث يخًىخت سطىذ زىل بانسًم انسشاسة واَخقال( انهىاء) انًائع خشَاٌ خصائص زىل عذدٌ اسخقصاء انذساستحخُاول هزِ انُسبت يثم يخغُشة شكهُت عىايم حاثُش دساست حى. وانًسخطُم انًثهث و انًىخٍ انشكم حخضًٍ انهُذسُت االشكال(. re<1000) واطئ سَُىنذ عذد نًذي انساسىبٍ انًساكاة بشَايح اسخخذاو حى. بعضها يع يقاسَخها وحًج انسشاسة واَخقال اندشَاٌ خصائص عهً انطىل وزذة خالل انذوساث وعذد انباعُت (ansys 14 )انًسخطُم انًخًىج نهسطر االضطشاب شذة اٌ وخذ. انُخائح واسخخشاج انساكًت انًعادالث وزم انسشاسة واَخقال اندشَاٌ يدال نًساكاة زىل االضطشاب شذة صَادة اٌ وخذ كزنك. انطىل وزذة فٍ انذوساث وعذدَفسها انباعُت انُسبت عُذ انًخًىج انسطر ثى ويٍ انًثهث نهسطر يُها اكبش نزنك وَخُدت انسشاسة اَخقال يعايم حسسٍُ انً ادي انًخًىخت انسطىذ mailto:nasseer64@gmail.com 36-49 al-khw arizmi engineering journal,vol. using smart control system condition farag mahel mohammed* mustafa abdul *,**,***department of (received http://dx.doi.org/10.22153/kej.2016.05.001 abstract in iraq, the air conditioners are the principal cause of high electrical demand. in summer, the outer temperature sometimes exceeds 500c which significantly effects on the a/c system performance and power consumed. in the present work, the improvement in mechanical and electrical performance of split a/c system is investigated experimentally and analytically. in this paper, performance experimentally investigated to be efficiently compa accomplished via smart control system integrate with proportional pic16f877a micro-controller has been programmed with the pid and pwm codes to control the speed of the proposed dc condenser fan over wide range of speed, also it has been programmed to have a smart characteristics to protect the a/c system parts as the ability to detect a refrigerant leakage, condenser fan stop, and any obstacles for the fan air flow. a comparative study between the conventional and enhanced a/c system is performed. t proposed system exhibits better performance and saves more energy than the conventional performance (cop) of the splita/c system keywords: split air conditioner a/c, temperature control, fan drive, pid control 1. introduction air conditioning (a/c) system operates to modify an air attributes (temperature and humidity) for more comfortable circumstances. this could be achieved by distributing the conditioned air into an appropriated space like a building, house or vehicle to enh comfort and indoor air quality. air conditioners are the principal cause of high electrical demand. in iraq country during summer, the outer temperature, sometimes, exceeds 50 type air conditioners are widely used in residential and commercial buildings in this country. the condenser unit is used in the a/c system for heat rejection process, which is mostly air cooled arizmi engineering journal,vol. 12, no. 4, p.p. 3649 (2016) using smart control system to enhancement the conditioning system performance farag mahel mohammed* jamal abdul-kareem mohammed** mustafa abdul-sattar jabbar*** *,**,***department of electromechanical engineering / university of technology *email: drfaragmahel@yahoo.com **email: jamalshwesh@gmail.com ***email: mustafa4eem@yahoo.com (received 15 march 2016; accepted 5 may 2016) http://dx.doi.org/10.22153/kej.2016.05.001 in iraq, the air conditioners are the principal cause of high electrical demand. in summer, the outer temperature significantly effects on the a/c system performance and power consumed. in the present work, the improvement in mechanical and electrical performance of split a/c system is investigated in this paper, performance and energy saving enhancement experimentally investigated to be efficiently compatible with elevated temperature weathers. accomplished via smart control system integrate with proportional-integraldifferential pid alg controller has been programmed with the pid and pwm codes to control the speed of the proposed dc condenser fan over wide range of speed, also it has been programmed to have a smart characteristics to protect the parts as the ability to detect a refrigerant leakage, condenser fan stop, and any obstacles for the fan air flow. a comparative study between the conventional and enhanced a/c system is performed. t erformance and saves more energy than the conventional a/c system are improved by about 20.56%. split air conditioner a/c, temperature control, fan drive, pid controller, pic16f877a microco air conditioning (a/c) system operates to modify an air attributes (temperature and humidity) for more comfortable circumstances. this could be achieved by distributing the conditioned air into an appropriated space like a building, house or vehicle to enhance thermal air conditioners are the principal cause of high electrical demand. during summer, the outer temperature, sometimes, exceeds 500c [1]. splittype air conditioners are widely used in residential and commercial buildings in this country. the condenser unit is used in the a/c system for heat rejection process, which is mostly air cooled condenser. the operation of air cooled condensers is more economic if compared with water cooled and evaporative-cooled condensers. the performance of an a/c system may be enhanced via reducing the compressor power consum increasing the cooling capacity and hea decreasing the refrigerant pressure reducing the difference in pressure betwee condenser and evaporator. yu and chan [2] presented how the of performance of air-cooled chillers can be enhanced by using variable speed condenser fan. the condenser fan has number of speed giving the required air flow. the condensing temperature control (ctc order to achieve maximum cop. al-khwarizmi engineering journal (2016) the split air kareem mohammed** electromechanical engineering / university of technology in iraq, the air conditioners are the principal cause of high electrical demand. in summer, the outer temperature significantly effects on the a/c system performance and power consumed. in the present work, the improvement in mechanical and electrical performance of split a/c system is investigated enhancement of a split-a/c system was weathers. this improvement is differential pid algorithm. the controller has been programmed with the pid and pwm codes to control the speed of the proposed dc condenser fan over wide range of speed, also it has been programmed to have a smart characteristics to protect the parts as the ability to detect a refrigerant leakage, condenser fan stop, and any obstacles for the fan air flow. a comparative study between the conventional and enhanced a/c system is performed. the results show that the erformance and saves more energy than the conventional one. the coefficient of ler, pic16f877a microcontroller. condenser. the operation of air cooled condensers is more economic if compared with water cooled cooled condensers. the performance of an a/c system may be enhanced reducing the compressor power consumption, capacity and heat rejection, refrigerant pressure losses, or reducing the difference in pressure between condenser and evaporator. resented how the coefficient cooled chillers can be by using variable speed condenser fan. has number of speed stages for giving the required air flow. the condensing ctc) system was used in maximum cop. with this control farag mahel mohammed al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 3649(2016) 37 system, the condensation temperature is adjusted based on the chiller heat load together with the ambient temperature via controlling the speed of condenser fan. elsayed and harir [3] investigated the effect of using a variable speed condenser fan on the performance and consuming power in small size air conditioner. they used a pid algorithm to control the condenser fan speed together with the ambient temperature. it was found that the compressor power consumption is reduced by 10% when the condenser fan’s air flow increased by 50%. mohammed, et al. [4] investigated how the performance of a split air conditioning system could be improved via using a water mist pid controller. the water flow rate was controlled by varying the speed of the water pump using pid algorithm. the results show that the improved system provides better performance and energy saving than the conventional system. the (cop) are improved by 44.56% , and over a wide range of ambient air temperatures up to 570c. singh, et al. [5] designed and implemented a pid control system to improve the performance of an a/c system through controlling the speed of condenser fan. this system had four input signals. these inputs receive signals denoted as an energy consumption value of a compressor, energy consumption value of a variable speed condenser fan, outdoor temperature, and condensation temperature, respectively. the output provides a control signal to the variable speed condenser fan. ng, et al. [6] investigated the possibility of executing a predictive controller for an automotive air conditioning (aac) provided with a variable speed compressor (vsc) based on adaptive neural network (ann). a comparative evaluation is implemented between the adaptive controller and other two control schemes, known a model predictive controller mpc based on offline trained ann model and a conventional pid controller. the experimental results identify the supremacy of the proposed control scheme with reference tracking in addition to disturbance rejection caused by its adaptation capability in tacking over the real time aac system behavior over the wide range of process conditions. islam, et al. [7] analyzed an evaporately-cooled air-conditioning unit performance, experimentally and numerically. experimental layout is performed by rebuilding commercially available air-conditioning unit and installing comprehensive instruments containing controllers and sensors. experimental results showed that the increase of cooling effect and reduction of compressor lift improve the cop of the evaporately-cooled air-conditioning unit by about 28%. the literature survey revealed a number of studies in the field of performance improvement of a split a/c system among them, using variable speed condenser fan algorithm [2] which used a ctc system equipped with air-cooled chillers. in contrast, the current study deals with pid algorithm prepared with the split-a/c system. unlike the work of elsayed and harir [3] which uses a pid algorithm to control the speed of a ac fan, simultaneously with the ambient air temperature between 300c and 420c, the current study uses a pid algorithm to control the speed of a proposed dc condenser fan that is compatible to the high speed range up to 2000 rpm. the speed is simultaneously controlled with the condenser saturation temperature tc, and the ambient air temperatures take rise between 350c and 570c to simulate a weather condition in iraq country. the work of mohammed, et al [4] used a pid algorithm integrated with the water mist technology, while the present work uses a pid algorithm to adjust the speed of a condenser fan. the aim of this work is to enhance the performance of split a/c system including parameters such as; compressor power consumption (wcomp), cooling capacity (qevap), condenser capacity (qcond), copu, and cop at elevated ambient temperature. the variable speed of dc motor condenser fan adjusted over two intervals of ambient temperature (35-40)0c and (40-57)0c. a smart control system (scs) was designed and implemented to control the speed of the dc motor condenser fan via pid controller and pwm technique. 2. experimental setup 2.1 split air conditioning system and environmental simulation room (esr) the split a/c system consists of the fundamental units of vapor compression system; condenser, evaporator, expansion valve, and compressor. a split a/c system is experimentally tested to determine an actual standard a/c system performance. a schematic illustration of the experimental setup is shown in fig. 1. the split a/c system was tested under standard environment condition using esr system shown in fig. 2. the proposed system has 2.499kw nominal capacity in addition to use refrigerant r22. the condensation unit has an ac propeller fan that replaced with a dc propeller fan that have some benefits if compared with ac fan such farag mahel mohammed al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 3649(2016) 38 as: high efficiency, more energy saving, low noise, operate at low speed 1/3 base speed, control flexibility, pwm technique easy to use, operation temperature of dc fans less is than that of ac fans (less power consumed) [8]. the gas flow meter type kf500 shown in fig. 2 is connected to the section line to measure a refrigerant flow rate. the esr system is built to simulate the environment condition in iraq. the esr system consists of two separated zones: indoor unit zone and outdoor unit zone. the esr system’s construction and properties are: 1. full isolated system using sandwich panel. 2. manual temperature control system to adjust the temperature of indoor and outdoor zone at a desired value. 3. two separated ducts system integrated with several stages of heater to supply air with a desired temperature for the two separate zones. 4. full isolated watch glass to monitor the a/c system. 5. control panel to monitor: temperature, dc voltage, dc current, ac voltage, ac current, and gas flow rate. the esr system is more compatible with the proposed control system scs. esr system gives more accuracy for the experiment results. it gives wide range of air temperature supplied to the indoor and outdoor units and also gives a good mixing, and distribution for temperature and air flow supplied to the indoor and outdoor units. 2.2 smart control system (scs) 2.2.1 hardware implementation the scs system is controlled using microchip (pic16f877a) microcontroller as shown in fig. 3. the scs circuit design, construction, and development are programmed and simulate using proteus professional software and picbasic pro pbp compiler. the microcontroller pic16f877a based automatic variable speed condenser fan system is applied to provide the functionality to implement automation characteristic. the condenser fan speed automatically change according to the condenser saturation temperature tc. the scs used a pid algorithm integrated on a pic16f877a microcontroller to control the condenser fan according to the tc variation. the control system measures the tc coming from the integrated circuit (ic) lm35 and determines the error signal. the system indicates the tc from the pic16f877a and it displayed it on the liquid crystal display (lcd). the condensation temperature is kept constant via pid controller over the ambient temperature (35-40)0c. over this range the control system will change to constant mode with maximum speed. the ambient temperature data is acquired from other lm35dz temperature sensor and comparing it with the condensation temperature data of the first lm35dz to detect a malfunction caused by any leakage or condenser fan stop. the speed of condenser fan is controlled using pwm technique and full h-bridge motor driver bts9760b, to control the input dc voltage [9], where: ���� = ��� � � … (1) 2.2.2. software implementation the software is implemented to perform the following three functions: 1. pid controller with pwm technique for controlling the speed of condenser fan. 2. refrigerant leak detection program. 3. program detection for condenser fan stop and/or obstacles which opposes condenser air flow (condenser fins needed to be clean). the flowcharts of these three programming modes are shown in fig. 4. • picbasic pro™ compiler (pbp) this compiler is used to build a program and generate hex file to setup a microcontroller pic16f877a with pid algorithm and to generate pwm signals. the picbasic pro™ compiler (pbp) makes it even quicker and easier to any one for programming the microchip technology’s powerful pic® microcontrollers [10]. • proteus software proteus 7.0 is a virtual system modeling (vsm) that combines circuit simulation, animated components and microprocessor models to cosimulate the complete microcontroller based designs. it is a good tool for engineers to test their microcontr4oller designs before constructing a physical prototype in the real world [11]. fig. 5 shows the control circuit implementation and simulation with proteus professional software. • coolpack software the coolpack package is a general and comprehensive simulation program that would give the user all the flexibility in terms of handling many different system designs and farag mahel mohammed al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 3649(2016) 39 investigation purposes. the coolpack was developed in the department of energy engineering in the technical university of denmark (dtu) (2001) [12]. 2.2.3 the parameters exactions for the approximate model of condenser unit the step response method is the better approximation model according to the actual response of the condenser plant. this response is a first order system with transportation delay. the response is represented by three parameters, l time delay, k forward gain and t time constant. these are found by drawing a tangent to the step response at its point of inflection and noting its intersections with the time axis and the steady state value as shown in fig. 6. fig. 7 shows the actual response of the condenser unit [13]. �� � = ����� ���� … (2) where l=2.307 sec, the t=5.3846sec and k=0.2267. so, the transfer function is: �� � = �.���� ����.�� !."#$���� …(3) 2.2.4. pid controller design the open loop ziegler-nichols method (indirect method) is used to determine the pid controller coefficients kp, ki, and kd. this method is most known and most widely used for pid controller tuning in thermal application. the controller determines the error signal e(t) that represents the difference between the desired and the measured value. this signal will generate a control signal. the drive control signal is u(t). the pid controller can be mathematically represented by: %�&� = kp e�t� + ki∫ e�t� + kd 0���� 0� … (4) this equation can also be represented in the sdomain by applying the laplace transform, as follows: 1� � = e�s� 4kp + 56 7 + kd s9 … (5) with zero initial conditions, the gains of the three terms of the controller (the proportional kp, derivative kd and integral ki) are set by using znm. the gains kp, kd and ki are evaluated by using controller parameters (k, l, and t) of g(s), which are experimentally evaluated [13]: kp = 1.2 t/k*l … (6) ti = 2 l … (7) td = 0.5 l … (8) the obtained results are: kp = 12.3547; ti= 4.614sec; td = 1.1535sec, so: ki = 5:;6 = 2.6776 … (9) kd = kptd = 14.2511 … (10) after experimentally fine tuning, the pid coefficients were found as follows: kp=10.23, ki=1.92, and kd=12.35. 3. formula used the parameters used for investigating the performance of each system can be computed via the following equations [14]: 1. heat transfer of condenser is computed by equation: <=� 0 = >? @�ℎ� − ℎ"� … (11) 2. heat transfer at evaporator can be calculated as: <�cde = >@? �ℎ� − ℎ$� … (12) 3. power consumed by a compressor: wg = v × i × cosɵ … (13) 4. coefficient of performance (cop): c. o. p = opqrs tu … (14) 5. heat rejection ratio = gvwxyzy[ g\:\g6]^ gvv_6w`g\:\g6]^ … (15) 6. copu = =��a b d=ed= �c�de� ���da e�� e�f�@�de� …(16) farag mahel mohammed fig. 1. a (b) fig. 2. esr system: (a) overall esr system, fig. 3 no. components 1 indoor unit zone 2 outdoor unit zone 3 heaters 4 duct system 5 gas flow meter, kf500 6 slide wall 7 control panel 8 variac 9 main circuit breaker 10 watch glass 11 low pressure side gages 12 high pressure side gages al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 3 40 (a) a schematic view of the experimental apparatus. (c) esr system, (b) pipes, air duct, and measurements , (c) a/c indoor unit. fig. 3. the smart control system scs. no. components 13 temperature recorder 14 pipe line 15 indoor unit discharge duct 16 outdoor unit discharge duct 17 evaporator drain 18 condensing unit 19 inside outdoor unit zone 20 evaporating unit 21 discharge duct 22 spot led 23 supply duct to indoor unit zone khwarizmi engineering journal, vol. 12, no. 4, p.p. 3649(2016) (d) c) a/c outdoor unit , (d) outdoor unit discharge duct supply duct to indoor unit zone farag mahel mohammed al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 3649(2016) 41 (b) pic16f877a configurations turn off compressor display fan stop or clean condenser fins pid routine and hpwm1 read temperature s1, s2 start conversion start s2 <= 400cif is s1-s2 > 20 is s2 > 40 is s1-s2 >15 end turn off compressor display fan stop or any obstacle apposes condenser air flow no no yes yes a)( yes no introduce pic16f877a international rc osc config. lcd connection config. i/o port config. a/d converter config. port c hpwm with duty cycle = 131 config. variables call delay read temperature s1, s2 pid routine display refrigerant leak start conversion is s1-s2<15 end start farag mahel mohammed al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 3649(2016) 42 fig. 4: flowcharts for: a) pic configurations and leak detection scheme, b) pid routine scheme for fan stop and obstacles detection, c) pid routine scheme yes no yes start conversion read temperature s1, s2, s3 calculate integral term cumulative error calculate proportional term calculate error = s1-51 calculate error = s1-51 read temperature, s1 start conversion is error = 0 pic16f877a configurations start set hpwm1 portc.2 duty1 =duty1+pt+it+dt previous error register calculate derivative term pid cycle time delay is error < > 0 duty2= duty1 hpwm1, portc.2 end (c) no farag mahel mohammed al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 3649(2016) 43 fig. 5. control circuit implementation and simulation with proteus professional software. fig. 6. scheme of identification method. fig. 7. actual response. 4. results and discussion the ambient air temperature effected the performance and the energy saving of an a/c system. as the air flow increase of condenser fan the heat recovery for the condensing unit increase, consequently the condensing temperature will decrease. in the case of studying the effect of using a pid controller on the system performance, it is found that, when the pid controller is processing over the range (35-40)0c of ambient temperature, the performance coefficients of split a/c system have a good arrangement with very small deviation from the programmed performance at 350c ambient temperature, while at the constant mode operation with the maximum fan speed and over the range (41-57)0c ambient temperature, the performance coefficients have been improved, but not as the previous range. fig. 8 shows the effect of variation condenser inlet air temperature on the refrigeration cooling capacity. it is clear that the cooling capacity was increased as a pid controller is used due to the increase of air flow rate as shown in fig. 9. the increase of air flow will decrease the condensation temperature, due to increase the heat rejected by the condenser unit as shown in fig. 10. at 400c and 570c ambient temperature, the cooling capacity of the conventional system decreased by 7.80% and 30.77%, respectively, while for the proposed system are decreased by 0.88% and 19.36%. fig.11 shows the effect of condenser inlet air temperature variation on the condenser capacity. it is clear that the condenser capacity is increased after using a pid controller due to increase the air flow rate. the increase of air flow decreases the condensation temperature, due to increase the heat rejected. for proposed system, 36 41 46 51 56 0 20 40 60 co n d e n sa ti o n te m p e ra tu re ,c time, sec farag mahel mohammed al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 3649(2016) 44 the decrease of condensation temperature is caused by increasing of compressor volumetric efficiency, due to decrease of pressure ratio. the condenser capacity of the conventional system at 400c and 570c are decreased by 5.77% and 23.86% respectively, and for the enhanced system decreased by 0.86% and 14.85% respectively. fig.12 shows the effect of variation condenser inlet air temperature on the cop. it is clear that, the cop is increased after adding a pid controller due to increase the cooling capacity and the decrease of compressor power consumption as shown in fig.13. the decrease of the condensation temperature increases the cooling capacity as well as the refrigerant flow rate as shown in fig.14. the cop of the conventional system decreased at 40 0c and 57 0c by 18.83% and 56.97% respectively, and for the enhanced system decreased by 1.8% and 36.41%. fig.15 shows the effect of condenser inlet air temperature variation on the copu. it is clear that, the copu was improved with adding a pid controller due to decrease of compressor power consumption and increase of refrigeration cooling capacity. as the condensation temperature decrease the heat rejection ratio decrease as shown in fig.16. this lead to decrease the compressor power consuming gained. the gained of copu for the conventional system at 400c and 570c are decreasing by 17.13% and 56.04% respectively, but for the enhanced system are decreased by 14.03% and 43.6 %. fig.17 shows the difference between refrigerant pressures in/out put of the condenser and the pressure drop caused by the condenser unit. fig.18 show the difference between refrigerant pressures in/out put of the evaporator and the pressure drop caused by the evaporator unit. it can be shown that the pressure drop increases with the increase of ambient temperature. fig.19 shows the variation of evaporating tepmerature via variation of condenser inlet air temperature at 270c inlet air temperature to evaporator. fig.20 and fig.21 show the output of coolpack software for the conventional and improved system. these figures present the performance of the two systems on p-h diagram with the variation of ambient temperature over the range (35-57)0c. it is clear that the performance of the system after addition of pid controller is improved through decrease of head pressure due to increase the heat rejected by the condenser unit. detection system of three cases has been tested in practice and gave the desired results. leak detection system, fan stop detection, and obstacles in the fan pathway detection through giving alert on lcd display. fig. 8. effect of condenser inlet air temperature fig. 9. air flow variation via condenser inlet air variation on cooling capacity. temperature. 35 37 40 45 50 57 farag mahel mohammed fig. 10. condensation temperature variation for convensional and improved system. fig. 12. effect of condenser inlet air temp variation on cop. fig. 14. effect of condenser inlet air tempe variation on refrigerant flow for the two systems 35 37 40 45 35 37 40 45 50 57 35 37 40 al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 3 45 tion temperature variation for fig. 11. effect of condenser inlet air temperature variation on condenser effect of condenser inlet air temperature fig. 13. effect of condenser inlet air variation on compressor power consumtion effect of condenser inlet air temperature fig 15. effect of condenser inlet air two systems. variation on unit coefficient of performance 45 50 37 40 45 50 35 37 57 37 40 45 50 khwarizmi engineering journal, vol. 12, no. 4, p.p. 3649(2016) effect of condenser inlet air temperature on condenser capacity. effect of condenser inlet air temperature compressor power consumtion. effect of condenser inlet air temperature unit coefficient of performance. 35 37 40 45 50 57 40 45 50 farag mahel mohammed al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 3649(2016) 46 fig. 16. effect of condenser inlet air temperature fig. 17. condenser pressure in/out variation with the variation on heat rejuction ratio. variation of condenser inlet air temperature. fig. 18. evaporator pressure in/out variation with fig. 19. variation of evaporating temperature via the variationof condenser inlet air temperature. vartiation of condenser inlet air temperature at 270c temperature to evaporator. fig. 20. p-h diagram for conventional system over (35-57)0c. 35 37 40 45 50 57 35 37 40 45 50 57 35 37 40 45 50 57 35 37 40 45 50 57 farag mahel mohammed al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 3649(2016) 47 fig. 21. p-h diagram for improved system over (35-57)0c. 5. conclusions this work investigates the performance enhancement of a split a/c system, in the hot weathers. the pid controller has been successfully integrated with scs with low cost and high efficiency. from the experimental results obtained, the following concluding remarks drawn: 1. the use of pid controller were achieved a good performance improvement for the a/c system, specifically, over the range (35-40)0c ambient temperature. 2. the compressor power consumption has been reduced by (5.96-34.09)% over the range (3757)0c ambient temperature. 3. the decreasing rate of cooling capacity, condenser capacity, cop, and copu for the proposed system is lower than the conventional system. 4. fault detection can easily use with the proposed scs, which add additional reliability, stability, safe operation, protection and long life of the a/c system parts. 5. the proposed scs is more compatible with the weather condition in iraq country, and the using of it in large scale a/c systems may give big amount of overall energy saving. nomenclature abbreviation meaning of abbreviation a/c air conditioning system ac alternative current cosɵ power factor cop coefficient of performance copu unit coefficient of performance dc direct current h1 enthalpy of refrigerant out from evaporator (kj/kg) h2 enthalpy of superheated refrigerant (kj/kg) h3 enthalpy of sub-cooled refrigerant (kj/kg) h4 enthalpy of refrigerant entering to evaporator(kj/kg) i compressor input current (amp) kd derivative gain ki integral gain kp proportional gain mr refrigerant mass flow rate (kg/sec) qcond condenser capacity (kw) qevap cooling capacity (kw) rh relative humidity tc condenser saturation temperature (0c) t period of pwm signal (sec) ton time on of switching (sec) v compressor supply voltage (volt) vin 12v battery to supply voltage (volt). vout average voltage supply to dc fan motor (volt) wcomp compressor input power (watt) notation 133 standard duty cycle at 35 c0 40c0 ambient temperature 20c0 temperature difference between tc(s1) and ambient(s2) 51 tc set point temperature or desired temperature farag mahel mohammed al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 3649(2016) 48 6. references [1] iraqi meteorological organization and seismology, 2015, www.meteoseism.gov.iq. [2] f. w. yu and k. t. chan, "advanced control of heat rejection airflow for improving the coefficient of performance of air cooled chillers", applied thermal engineering, vol. 26, issue 1, january 2006, pp. 97-110. [3] a. o. elsayed and a. s. harir, "effect of condenser air flow on the performance of split air conditioner", world renewable energy congress, conference paper, 8-13 may 2011, pp. 2134-2141. [4] f. m. mohammed, j. a. mohammed, and m. a. jabbar," energy saving and performance improvement of a split air conditioning system using water mist pid controller", wulfenia journal, vol. 22, issue 9, sep. 2015, pp. 96-104. [5] a. singh, thomas j. m., frank c., and ozgur y.g, variable speed condenser fan control system, united states patent, us 7,845,183 b2, dec. 7, 2010. [6] b. c. ng, i. z. m. darus, h. jamaluddin, and h. m. kamar, "application of adaptive neural predictive control for an automotive air conditioning system", applied thermal eng. vol. 73, issue 1, dec. 2014, pp. 12421252. [7] m.r. islam, k.a. jahangeer, and k. j. chua, "experimental and numerical study of an evaporatively-cooled condenser of airconditioning systems", energy, vol. 87, issue 1, july 2105, pages 390-399. [8] engineers edge, llc, improving fan system performance, sourcebook for industry, u.s. department of energy efficiency and renewable energy, april 2003 [9] austin hughes, electric motors and drives fundamentals: types and applications, 3rd edition, elsevier ltd, 2006. [10] dogan ibrahim, picbasic project, linacre house, jordan hill, oxford ox2 8dp, uk, 2006. [11] xtronic circuits, proteus 7, http://xtronic.org/download/proteus-7-aresisis/. [12] jakobsen, a., rasmussen, b., d., skovrup, and m., j. engedal, simulation program handling many different system designs and investigation purposes, a coolpack package, department of energy engineering, technical university of denmark (dtu), 2001. [13] karl johan, aström , and richard m. murray, feedback systems, an introduction for scientists and engineers, version v2.10c, princeton university press, pp302, march 4, 2010. [14] g. f. hundy, a. r. trott and t. welch, refrigeration and air-conditioning, 4th edition, elsevier ltd, 2008. ���� 4، ا���د�12� � ا���ارز�� ا������� ا��� � �ج ��� ���� ،2016( 49-36( 49 � � ا�#��ام -%$م ��+�ة ذ(� �#�)�' اداء ��%��$ت ا�#"��! ذات ا����ات ا���� �+�4 �01 ا�)#$ر 03$ر** �3$ل �01 ا�"�/. ����* �ج ��� �����*** � ا������ ا����و���������*** ،**،*��/ � !�!� �ا�$��#� ا�"� drfaragmahel@yahoo.com *%ا�)�'� ا&��"�و�: jamalshwesh@gmail.com %ا�)�'� ا&��"�و�: ** mustafa4eem@yahoo.com : ا�)�'� ا&��"�و�%*** �� ا��5 ˚ م٥٠وأن در �ت ا�@�ارة 7% 7<? ا�<�9 �� ت"$�وز ا�ـ . ��;!��ت ت���9 ا��!اء 7% ا�#�اق ا��)5 ا��-�4 &�"�3ك ا��1رة ا����.�-�� ,�+�ً �ت# ً����gت ت���9 ا��!اء، أ��!;�� %7 ��h�"�iأداء و��1ار ا��1رة ا� jhk ظ!@h� ?�m. �no' اpوھ .r��7% ا&داء ان ا��را�� ا�@���� ت�#j ا�j ت@s�1 ت@ �� در �ت ا�@�ارة ا��iت+� �u�@ih ا��tر %k ـــ�h>+�iـــ!��ت ت�ــــ��9 ا��!اء ا�;�i� ��h�"�iوا��1رة ا� ،v��(� %wم ذ�;� y� ��"h���� 3ل[ r� \وذ� )smart control system scs (. �7و�#iة ا��]�� proportional-integraldifferential pid(ـ وا�pي .�وره تy� ^"h���� _i ]!ارز��� ا� algorithm .( s��ا�� �]��iان ا�)pic16f877a microcontroller ( ة�]�� )pulse widthو algorithm pid ((تt. ^"$��. _i!ارز��� ا� modulation pwm (yى وا��i.ا�"���9 و ��!;�i� 9c�iا� �gو�� �k�� jhk ة�]����[� ا�wpi!ر تr� ،��. _i ا ? ا�i�7ن ا� \�pwو \h"i�� ^"$ �>[-9h"ا� r� ��!;�iاء ا�d ا �'�i@� ��wذ e ،v�hc"ا� y-�� %7 5'��و ا��rk 9m ا�#!ا-s 7% �$�ى ، ت!s7 ��و�g ا�c� ،9c�i? ا��9m ا�rk ��(i ا�" 9c�ih� ?[ا��!اءا��ا .��hi#ا� v-�"���، .#� ا�@<!ل jhk ا��@iوا� �'��h1"ا� ��!;�ih� درا�� ��1ر�� ?ik �ا��"�-v ان ا��;�م ا�1i"�ح ظ�� f�g اظ��ت، ت �'��h1"ا� ��!;�iا� y� ً���7 ��1ر�� ��h�"�iو ا��1رة ا� ��!;�i7% اداء ا� r��) f�g) coefficient of performance cop ان �#��? ا&داء . ت@ �;!�� ا�"���9 ت@��1i. rار ٪i�.٢٠.٥٦. 1-11 al-khwarizmi engineering journal,vol. 12, no. high order sliding mode observer controller desi shibly ahmed al *,** department (received http://dx.doi.org/10.22153/kej.2016.06.002 abstract a perturbed linear system with property of strong observability ensures that there is a sliding mode observer to estimate the unknown form inputs together with states estimation. in the case of the electro piston position measured output, the above property is not were used to build a dynamic structure that satisfy the condition of strongly observable. observer (hosmo) was used to estimate both the resulting unknown perturbation thereafter with one signal from the whole system (piton position), the piston position make tracking to desire one with a simple linear output feedback controller after canceling the perturbation term. the numerical simulation results show forcing the piston position to follow the desired reference position. moreover keywords: electro-hydraulic system, strong 1. introduction in many tracking or regulating problem design, it is impractical to assume that all the system phase variables are measured [1, chapter 7]. problem of states reconstruction together with perturbation (unknown inputs and parametric uncertainties) estimation is one of the most important studies in modern control theory [ the computation of system states and perturbation can be done by a dynamical system called robust observer [1, chapter 7]. for perturbed linear system the traditional luenberger observer derived the state estimation error to bounded region around the origin [ chapter 7]. in addition to that the estimation error with sliding mode observer based on first order sliding mode converge asymptotically origin if the measured outputs have degree one with respect to the perturbation term [3, chapter 3]. but sliding mode observer based on high order sliding mode skip the need to the khwarizmi engineering journal,vol. 12, no. 4, p.p. 111(2016) high order sliding mode observer-based output feedback controller design for electro-hydraulic system shibly ahmed al-samarraie* mustafa h. mishary department of control and systems/ university of technology *email: 60132@uotechnology.edu.iq **email: albmustafa@yahoo.com (received 7 march 2016; accepted 15 june 2016) http://dx.doi.org/10.22153/kej.2016.06.002 property of strong observability ensures that there is a sliding mode observer to estimate the unknown form inputs together with states estimation. in the case of the electro piston position measured output, the above property is not met. in this paper, the output and its derivatives estimation used to build a dynamic structure that satisfy the condition of strongly observable. a used to estimate both the resulting unknown perturbation term and the output derivatives. with one signal from the whole system (piton position), the piston position make tracking to desire one with feedback controller after canceling the perturbation term. tion results showed excellent performance of the proposed output feedback controller in forcing the piston position to follow the desired reference position. moreover, the control effort spent hydraulic system, strong observability, unmatched disturbance, high order sliding mode observer in many tracking or regulating problem design, it is impractical to assume that all the system phase variables are measured [1, chapter 7]. the problem of states reconstruction together with perturbation (unknown inputs and parametric mation is one of the most important studies in modern control theory [2]. the computation of system states and can be done by a dynamical system called robust observer [1, chapter 7]. for perturbed linear system the traditional server derived the state estimation error to bounded region around the origin [3, chapter 7]. in addition to that the estimation error with sliding mode observer based on first order asymptotically to the have relative degree one with respect to the perturbation term , chapter 3]. but sliding mode observer based on high order sliding mode skip the need to the relative degree one, because this observer include a robust (exact with mea differentiator [3, chapter 7]. the relative degree one with respect to the perturbation is a restriction to design an observer [4]. as a literature review, improvement of the sliding mode control for the electro hydraulic system ( was studied in [5] such that the dynamic friction model of the ehs was inserted in the simulation model instead of the one that to be controlled. an approximate ideal sliding mode control with varying boundary layers fo [6] to improve the position tracking performance such that the experimental results have shown robustness against the various set points. by combining the sliding mode control and a simple robust method, the adaptive sliding mode cont for the ehs was presented by [ results have shown a good performance of the position tracking. al-khwarizmi engineering journal (2016) based output feedback hydraulic system mishary** systems/ university of technology property of strong observability ensures that there is a sliding mode observer to estimate the unknown form inputs together with states estimation. in the case of the electro-hydraulic system with met. in this paper, the output and its derivatives estimation a high order sliding mode term and the output derivatives. with one signal from the whole system (piton position), the piston position make tracking to desire one with excellent performance of the proposed output feedback controller in the control effort spent was minimal. high order sliding mode observer. relative degree one, because this observer include a robust (exact with measurement noise free) , chapter 7]. the relative degree one with respect to the perturbation is a restriction ]. as a literature review, the performance improvement of the sliding mode control for the ulic system (ehs) position tracking ] such that the dynamic friction model of the ehs was inserted in the simulation model instead of the one that to be controlled. an approximate ideal sliding mode control with varying boundary layers for ehs was proposed by ] to improve the position tracking performance such that the experimental results have shown robustness against the various set points. by combining the sliding mode control and a simple robust method, the adaptive sliding mode control for the ehs was presented by [7] such that the results have shown a good performance of the shibly ahmed al-samarraie al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 111(2016) 2 observer based back stepping control design for the ehs was studied in[8, 9] such that the proposed controller was designed in the presence of both friction and load force where the ultimate boundedness of the position tracking error was guaranteed. in [10] a nonlinear model of the ehs dynamical model have been developed such that a robust �� position control extended with integral action was proposed, where the experimental results have shown the robustness of the closed loop system against the parametric perturbation and the load force. hosmo with exact states and unknown bounded inputs observation for strongly observable system was proposed by [2]. in [11] the states and the unknown unbounded (but only requires boundedness of at least one of their high order derivatives) inputs were estimated. a global finite time exact observation of the state vector for general (the measured outputs are perturbed by the same unknown form of the system dynamics with dimension of the unknown input vector less than the number of the measured outputs) strongly observable linear time invariant systems with bounded unknown lebesgue measurable inputs was proposed by [12]. the organization of this paper is as follows; the formulation of the problem statement is presented in section 2, while the hosmo based controller deign is introduced in section 3. in section 4 the electro-hydraulic system takes as a case study, while the simulation results and discussions are developed in section 5. 2. problem statement consider a dynamical system described by � ��� = �� ��� = ����, �� + �����, �� �� +�����, ��, � ��� = ����, ��, �� + �����, ��, �� � +�����, ��, ��, � � = �� �� � �� …(1) where, �����, ��, � and �����, ��, ��, � are the mismatched and matched unknown perturbation forms. the perturbation includes parametric uncertainties and the unknown bounded external inputs with knowing that that both � and �����, ��, � are assumed to be locally lipschitz. in addition � is assumed here to be the only measured output. the observability problem can be regarded as follows; the possibility to build a new dynamic system called robust observer depends only on given information called measured outputs used to reconstruct both of system states and unknown form [13, chapter 1]. the strong observability, that is required observability condition, confirms the existence of transformation matrix that transformed the original form dynamic to a phase variable canonical form such that there is a robust observer which is exact with measurement noise free to reconstruct both of states and the unknown form, such observer is a hosmo [3, chapter 7]. from an observer design point of view (eq. (1)) one cannot design an observer which used to reconstruct the unknown form along with states estimation due to the relative degree condition which is not satisfied here. the electro-hydraulic system is an example described mathematically by eq. (1). in modern control system the reduction of sensors devices produce less measurement noise, such that the proposed controller become more accurate in addition to cost reduction[2]. now consider the following assumption; assumption (1): the right hand side of ��� in eq. (1) is a differentiable function, i.e., ����, �� , �����, �� �� and �����, ��, � are smooth functions of ���, ��, � . based on the above assumption, eq. (1) can be transformed to a phase variable canonical form. as a result it can be obtained a strongly observable system such that the state variables vector is the output measurement and its derivatives. thereafter hosmo will be adapted here to reconstruct the resulting new unknown form together with new state variable vector estimation. the new unknown form means that a perturbation term resulted from differentiating ���. in addition to that the new unknown form of the resulting dynamic (canonical transformed form of eq. (1)) satisfies the matching condition where after estimating this form one can cancel it and then use any successful linear controller to drive � = �� to track desired one. the goal of this paper is to build a system dynamic related to the system dynamic as in eq. (1) and transform it to a phase variable canonical form via hosmo. then a linear state feedback will be designed to derive the output to follow the desired reference. 3. high order sliding mode observer based controller design keeping in mind the dynamic of eq. (1) and denoting that: shibly ahmed al-samarraie al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 111(2016) 3 �� = � = ��, �� = �� = ��, �� = �� = ��� �2 now by considering assumption (1) the model dynamic in eq. (1) can be rewritten as follows; ��� = �� + �� + ��� = � ! … �3 where: � = $������% , � = $0 1 00 0 10 0 0% , � = $ 00����% � = $001% , = (1 0 0) � = ��� � + �� + **+ � � + �� where � � + �� is assumed differentiable as mentioned above. therefore it can be seen that the dynamic in eq. (3) is strongly observable (see appendix a). the next step is devoted to design a hosmo to reconstruct the perturbation � together with estimating the new state �. it consists of building a standard luenberger observer together with a high order sliding mode differentiator. a standard luenberger observer for the system in eq. (3) is given by ,� = �, + �� + -�� − , = �, + �� + -� � − , … �4 where , ∈ ℛ�. define:2 = � − ,, then from eq. (3) and eq. (4) we obtain: �2� = �� − 2 + ��23 = 2 ! … �5 where 23 = � − , = � − , = 2. the traditional luenberger observer with � = 0 ensures the asymptotic convergence to zero for the estimation error due to that �� − is hurwitz [14] without the need to differentiating the output n-1 times. but with unknown bounded � the luenberger observer providing a bounded estimation error [3]. a high order sliding mode differentiator companied with luenberger observer confirms a finite time convergence of the resulting estimation error to zero as follow [3]: 566 7232�32�32839: :; = < �� − �� − � �� − �= 2 + < 000 �� − ��= � . . �6 from eq. (6), the state � and the perturbation � are estimated as follows; � = , + $ �� − �� − �% @� a232�32�3b … �7 � = �d�e@fd gh i283 − �� − �2 j … �8 equation (7) shows that, �� − , ⟶ 0 when 23 ⟶ 0. that means a luenberger observer is sufficient with � = 0. to this end, the derivatives of 23 to the third order are the basic implementation requirement of the above observer. a high order sliding mode differentiator is utilized in this work to get an exact (robust with noisy measurements) 3th order differentiation of signal 23 as follow; assume that the 3rd derivative has a known lipschitz constant m >| ���||�|pqr [3, chapter 7]. since ��� = 1 (see eq. (3)), thus m > |�|pqr. the hosmo dynamics is given by; � s�� = −tu mvw xs� − 23xyw z�[is� − 23j + s�s�� = −t� mvy |s� − s�� |\y z�[�s� − s�� + s�s�� = −t� mv\ |s� − s�� |g\ z�[�s� − s�� + susu� = −t� mvg |su − s�� |vg z�[�su − s�� + s]s]� = −t^ m z�[�s] − su� ��� � ��� �9 where t^ = 1.1, t� = 1.5, t� = 2, t� = 3,tu = 5 [3, chapter 6]. from eq. (9), eq. (7) becomes; �̀ = , + $ �� − �� − �% @� $s�s�s�% … �10 based on eq. (9) and eq. (10), eq. (8) becomes; �a = �d�e@fd gh ∗ csu − �� − � $ �� − �� − �% @� $s�s�s�%d …(11) by taking into consideration eq. (10) and eq. (11), the control law is proposed here as follows; � = �eveg f�^��̀�, �̀�, �̀� − �ag … �12 as a result eq. (3) becomes ���� = �� ��� = �� ��� = �^��̀�, �̀�, �̀� h … �13 where �^��̀�, �̀�, �̀� can be designed as any linear states feedback controller such that the system dynamics described by (13) is globally asymptotically stable. the control design idea presented here is depict in fig. (1), where the piston position is the only measured output. the feedback controller was designed based on higher order sliding mode observer. fig. 1. control design idea shibly ahmed al-samarraie al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 111(2016) 4 4. high order sliding mode observer based controller design for electrohydraulic system the mathematical model for electro-hydraulic system that used in this work is described by [15]; ���� = �� ��� = ����, �� + �� �� + �����, �� ��� = ����, �� + �� �� + ����, ��, �� � = �� i … �14 where �� is the piston position �j2�2k , �� is the piston velocity �j2�2k/z2m , �� is the pressure difference �n/j2�2k� , � is the control input (the current) �j� , �, ��, � and �� are the system dynamics nominal terms (includes nominal parameters only) with ��, �� > 0. in addition �� and �� are the mismatched and matched perturbations respectively. the nominal and the perturbation terms in system dynamics are given by; � ����, �� = − �p �o�� + p�� �� = qp ����, �� = − ursqtu �� − ursduvtu �� �� = ursdwxyztu{| {}~ �����, �� = ∆ ����, �� + ∆���� �����, �� = ∆ ����, �� + �� � = �ursdwxyztu{| + ∆�ursdwxyztu{| �! ∗ {}~ − z�[�� �� − ursdwxyztu{| {}~ ��� ��� � ��� ��� …(15) where: ∆ �, ∆��, ∆ �, and ∆�� are the uncertainty term and its assumed here that the variation in their parameters can reach 30% of their nominal values. as in assumption (1), ����, �� and �����, �� are differentiable functions. accordingly the electro-hydraulic system described in eq. (14) is equivalent to canonical system form that given in eq. (3). based on section 3 one can conclude the following; i. since the pair � , � in eq. (3) is observable, therefore, there is a gain matrix used to place the eigenvalues of matrix � − to stable one [14]. let the desired stable eigenvalues are 2���� − = �−1,−2,−3 then the gain matrix = (6 11 6)�. ii. with the aid of eq. (4) to eq. (11), and m = 10��, the reconstruction of the unknown form � along with the estimation of � are as follow; �̀ = , + $ s�6s� + s�11s� + 6s� + s�% … �16 �a = su + 6s� + 11s� + 6s� … �17 iii. the actual current control input is calculated by � = �eveg ��^��̀�, �̀�, �̀� − su − 6s� − 11s� − 6s�� … �18 for eq. (14), in spite of the complete system parametric uncertainties, the matching condition of �����, ��, � with the actual control input are not met and strong observability does not satisfied. however, with assumption (1), and the estimated states and perturbation via hosmo, the current control action as in eq. (18) solves all of the above challenges. moreover one can use any state feedback controller �^��̀�, �̀�, �̀� techniques to drives �� = �� to the desired position like lqr and the pole placement. in the present work a linear state feedback controller, uses �̀�, �̀� and �̀� and with desired negative poles values is given in eqs. (21) to (23) in the following section. 5. simulation results and discussions the obtained simulation results in this work are performed using the actual dynamics system as described by eq. (14) with the control law and the observer dynamics as given by eq. (18) and eq. (9) respectively. in addition the observer parameters are presented in section 4. the initial system states and initial observer states have been taken equal to �0.0001,0,0 , �0.0001,0,0 respectively. nominal electro-hydraulic system parameters are given in the following table. table 1, the system parameters [8]. the parameter description the nominal value (si units) p viscous damping coefficient. 19.84*103 ns/m ω ram area of the cylinder. 5.55 ∗ 10@� m2 v� total volume of the cylinder and the hoses between the cylinder and the servo valve. 1.75 ∗ 10@� m3 +p coefficient of the total internal leakage of the cylinder due to pressure. 1.5 ∗ 10@�u m5/ns shibly ahmed al-samarraie al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 111(2016) 5 o effective bulk modulus of spring. 70*103 n/m �� effective bulk modulus. 700 ∗ 10� n/m2 � �/{� cd is the discharge coefficient; w is the spool valve area gradient and � is the fluid density. 3.42 ∗ 10@] m3√nz j mass of the load. 20~250 kg }� supply pressure of the fluid. 10� n/meter� o� gain of the servovalve. 0.03 from which the parameters of eq. (15) have been obtained; � = −518.52 �� − 147 ��, �� = 4.11 ∗ 10@] � = −8.88 ∗ 10� �� − 0.024 ��, �� = 5.19 ∗ 10� �� = −∆ �518.52 �� − ∆ �147 �� + ∆� 4.11 ∗ 10@] �� �� = −∆ �8.88 ∗ 10� �� − ∆ �0.02 4 �� +� � � = �1641600 + ∆�1641600 �{10� − z�[�� �� − 5.19 ∗ 10� …(19) where |∆ � | ≤ �|� �| , is the parameter uncertainty, � � is the nominal parameter value and 0 < � < 1 is the uncertainty percent. keeping in mind that the unknown form (perturbation term) which resulted from the electro-hydraulic system based on eq. (3) is as follow: � = ��� � + �� + ��� � � + �� … �20 in the following the simulations are performed first for the open loop in order to examine the ability of the hosmo in estimating the first and second derivative of �� = � = ��, and also estimating the perturbation term �. second the results of the numerical simulations for the control system are presented where the control law uses the reconstruction transformed states �̀ and perturbation estimations �a as designed in section 4. 5.1. open loop system simulation results in this subsection the control input is set equal zero � = 0. for α = 0.1 the outputs of the hosmo are plotted in figures (2), (3) and (4) for estimating piston position, velocity and acceleration respectively while perturbation estimation is plotted in figure (5). one can be sure from these figures, that the estimating quantities converges to their actual values in an interval of time not exceeds 0.002 z2m. it can be noted also that the convergence time for the estimating quantities increased sequentially with the order of estimating states. fig. 2. open loop piston position �� estimation under � =  . � parametric uncertainties. fig. 3. open loop piston velocity �¡ estimation under � =  . � parametric uncertainties. fig. 4. open loop piston acceleration �� ¡ estimation under � =  . � parametric uncertainties. shibly ahmed al-samarraie al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 111(2016) 6 fig. 5. open loop ¢ estimation under � =  . � parametric uncertainties. in order to prove the estimator robustness and the powerful of the hosmo, the open loop simulation is repeated with α = 0.3. the estimation performance does not changed in spite of increasing the uncertainty percent α as can be deduced from figure (6) to figure (9). fig. 6. open loop piston position estimation �� under � =  . £ parametric uncertainties. fig. 7. open loop piston velocity �¡ estimation under � =  . £ parametric uncertainties. fig. 8. open loop piston acceleration �� ¡ estimation under � =  . £ parametric uncertainties. fig. 9. open loop ¢ estimation under � =  . £ parametric uncertainties 5.2. closed loop simulation results a piecewise constant and the sinusoidal are the desired piston positions which are considered in this work for the closed loop system simulation. in the following subsections the simulations are performed with � = 0.3, and the nominal controller �^��̀�, �̀�, �̀� will be designed using a simple pole placement control. the proposed nominal controller that drives the piston position to continuously differentiable desired one (as in sinusoidal case) is given as follows; �^��̀�, �̀�, �̀� = �8�* − ¤ a��̀� − ��* ��̀� − ���* ��̀� − ���* b … �21 where: ��* the desired piston position. while in the piecewise desired one the nominal controller is as follows; �^��̀�, �̀�, �̀� = −¤ a��̀� − ��* �̀� �̀� b … �22 as mentioned earlier, one can choose feedback gains ¤ to achieve desired eigenvalues as follows; shibly ahmed al-samarraie al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 111(2016) 7 �¤ = (39651480 348842 1023) 2�� ¥� + $001%¤¦ = �−340,−341,−342 i… �23 the simulation results for the closed loop control are presented in the next subsections. 5.2.1. piecewise desired piston position simulation results. figures (10), (11) and (12) have shown the piston position, velocity and acceleration of the electro hydraulic system respectively. it can be seen from these figures the actual piston position make tracking to desire piecewise signal with rise time approximately equal to 0.03 z2m and absolute tracking error less than 10@� j. as mentioned in the open loop results, hosmo also have shown an accurate estimation in closed loop simulation where in these figures the blue lines represents the electro-hydraulic dynamic variables and the green ones represents the outputs of the hosmo which were used as a states feedback in nominal controller �^��̀�, �̀�, �̀� . figure (13) refer to the pressure difference �� such that �� ∗ ω represents the required hydraulic force input to drive the piston position �� to piecewise desired one. however, it can be seen from this figure the max value that the force input reaches approximately ±28860 n. the estimation of the perturbation term �a that estimated by hosmo is clarified in figure (14) where the estimated quantity converge to actual one with time interval less than 0.01 z2m. this accurate estimation was used with negative feedback signal into the actual current control input to cancel the actual effect �. the actual current control input � that used to ensure the above performance which is represented by figure (15) does not exceed 3 j�. fig. 10. closed loop piston position �� under � =  . £ parametric uncertainties tracking desired piecewise position fig. 11. closed loop piston velocity �¡ under � =  . £ parametric uncertainties with desired piecewise piston position. fig. 12. closed loop piston acceleration �� ¡ under � =  . £ parametric uncertainties with desired piecewise piston position. fig. 13. pressure difference �£ under � =  . £ parametric uncertainties with desired piecewise piston position. fig. 14. closed loop ¢ estimation under � =  . £ parametric uncertainties with desired piecewise piston position. shibly ahmed al-samarraie al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 111(2016) 8 fig. 15. current control input under � =  . £ parametric uncertainties with desired piecewise piston position. 5.2.2. sinusoidal desired piston position simulation results. as in the case of piecewise desired piston position, figure (16) have shown the successful tracking of the piston position to desired one (sinusoidal) and this can be regarded as a challenge, because this tracking was constructed on the basis of knowledge of the measurement of the piston position only. in figures (17) and (18) the actual and the estimation of the piston velocity and piston acceleration are plotted. these figures reveal the accurate estimation of these physically quantities (velocity and acceleration) via hosmo. the demanded hydraulic force input �� ∗ ω in this case (sinusoidal reference) that can be noted form figure (19) oscillates between ± 727.05 n. figures (20) and (21) show the perturbation estimation �a and the actual current control input � respectively, where the current input does not exceed 0.02 j�. fig. 16. closed loop piston position �� under � =  . £ parametric uncertainties tracking desired sinusoidal position. fig. 17. closed loop piston velocity �¡ under � =  . £ parametric uncertainties with desired sinusoidal position. fig. 18. closed loop piston acceleration �� ¡ under � =  . £ parametric uncertainties with desired sinusoidal position. fig. 19. pressure difference �£ under � =  . £ parametric uncertainties with desired sinusoidal position. fig. 20. closed loop ¢ estimation under � =  . £ parametric uncertainties with desired sinusoidal position. shibly ahmed al-samarraie al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 111(2016) 9 fig. 21. current control input under � =  . £ parametric uncertainties with desired sinusoidal position. from the previous two simulation results (piecewise and sinusoidal references) the following question arises; why the amplitude of the current input for the piecewise case much larger than the sinusoidal case in spite of that, the amplitude for both desired signal are equal?. this disparity of the current input due to the piecewise case where the piston position has a sudden jump at certain points. accordingly at these points the slope is unbounded, therefore the hosmo make a sort of adaptation in order to cover this abrupt change leading to a control effort much larger than that one of sinusoidal case as shown in figures (15) and (21) respectively. as a matter of fact the control input (the current) is minimal for both type of desired position. it is meant by minimal that the controller, which will be able to regulate the error function 2 to the origin, will spend just the required effort in order to reject the perturbation term. canceling the perturbation terms, and then deals with the system as a nominal system and exactly specifying the system response characteristics is the control strategy that leads to minimizing the control effort. indeed one cannot apply the above mentioned strategy without an exact estimator like the hosmo. moreover the estimation process via hosmo can be made faster by choosing more appropriate gain matrix such that 2���� − are sufficiently far from the right hand side of the imaginary axis. 6. conclusion a hosmo based controller design is proposed to improve the piston position tracking for the electro-hydraulic system suffers from parametric uncertainties and unmatched disturbance with only position measured signal. by using only the piston position as a measured output, the hosmo is designed to estimate both the bounded differentiable unknown form and the states of the phase variable canonical system. our proposed controller uses the estimated perturbation to cancel its actual effect on system dynamics. then a simple linear output feedback controller based on pole placement was designed such that the piston position tracks the desired one. two desired position are considered which are piecewise and sinusoidal where the simulation results have shown an excellent estimations and tracking performance. 7. references [1] karl johan aström and richard m. murray, ''feedback systems", princeton university press, 2008. [2] leonid fridman, arie levant and jorge davila, "observation of linear systems with unknown inputs via high-order sliding-modes", taylor & francis international journal of systems science, vol. 38, no. 10, pp. 773–791, 2007. [3] yuri shtessel, christopher edwards, leonid fridman and arie levant, "sliding mode control and observation", springer science+business media new york, 2014. [4] m. l. j. hautus," strong detectability and observers*", elsevier science publishing co., inc., pp. 353-368, 1983. [5] miroslav mihajlov, vlastimir nikolić and dragan antić, " position control of an electro-hydraulic servo system using sliding mode control", facta universitatis, series: mechanical engineering, vol. 1, no. 9, pp. 1217 – 1230, 2002. [6] hong-ming chen, jyh-chyang renn and juhng-perng su, " sliding mode control with varying boundary layers for an electrohydraulic position servo system", springerverlag london limited, pp. 117–123, 2005. [7] cheng guan and shuangxia pan, " adaptive sliding mode control of electro-hydraulic system with nonlinear unknown parameters", elsevier ltd, pp. 1275– 1284, 2008. [8] daehee won and wonhee kim, " disturbance observer based backstepping for position control of electro-hydraulic systems", springer international journal of control, 2015. shibly ahmed al-samarraie al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 111(2016) 10 [9] daeheewon, wonhee kim, donghoon shin, and chung choo chung, " high-gain disturbance observer-based backstepping control with output tracking error constraint for electro-hydraulic systems", ieee transactions on control systems technology, 2014. [10] vladimir mili¢, zeljko situm and mario essert, "robust h_∞ position control synthesis of an electro-hydraulic servo system", elsevier isa, pp. 535-542, 2010. [11] francisco j. bejarano and leonid fridman, " high order sliding mode observer for linear systems with unbounded unknown inputs", taylor & francis international journal of control, vol. 83, no. 9, pp. 1920–1929, 2010. [12] leonid fridman, jorge davila and arie levant, "high-order sliding-mode observation for linear systems with unknown inputs", elsevier ltd, 2010. [13] sergey k. korovin and vasily v. fomichev, "state observers for linear systems with uncertainty", walter de gruyter gmbh & co. kg, 10785 berlin, germany, 2009. [14] j. o’reilly, "observers for linear systens", academic press inc. (london) ltd, 1983. [15] jinping yu, yuanchun ding and falu weng, " robust control for electro-hydraulic servo systems driven by doublerod actuators", ieee 3rd international conference on advanced computer control (icacc), 2011. appendix a recall eq. (3) with � = 0 ��� = �� + ��� = � ! … ��1 $����� % = $ � ��% � + $ 0 � ��%� … ��2 from matrices of eq. (3) we have: k©[o ¥$ � ��%¦ = 3, $ 0 � ��% = 0 … ��3 this shows that the relative degree between the output � and the unknown perturbation � is three. in other words and from the above procedure, a perturbed linear dynamical system as in eq. (3) has the strongly observability condition and it has no null dynamic (no invariant zeros). � ا�� ا ����ا���� � ��� � ا ��ارز�� ا ��� �� 4، ا � د12 ا ���� ،11-1 )2016( 11 � ��� !��"#)output feedback (%��و &��� ا�� ' �� * ��ا() ا , ا�+��دا ا رو ھ� ا ��1 0 /� � ا �#�� �* ���4 ��3ري *�� � ا�� ا ����ا�� "�** ا-5678) ا-34%2-12,)/وا-%/! ا-",+*ة )س&%ھ#"! **،* uotechnology.edu.iq@60132: ا-=*>& ا;-43*و:9* albmustafa@yahoo.com: ا-=*>& ا;-43*و:9** ا �5�� :?q,?j4r-s%6 t 6&اpa ا;o+*اب m,* ي-k:/?) ا-j+,) ا-?efg (h*+i& و21د 6*ا#c ذ) strong observability(7a@,) ا-?*ا#=) ا-<2>) ھ7>&رو-,` j6 y#26 y6*ج ا-?3=^ ا-?<7س 9u \7-) :/7م ا-z3*و). state variables(x46 q,?jg y6,*ات ا-7v-) ) unknown form inputs(?5*وu) ا)piston position measured output ( (,@7j-ا `bg)strong observability ((>>v46 *,m .cv=-ا اd9 ھu ، م&j4"g eg7>4f6 q,?jg ا-?3=^ و y#26 >"j4&م ) high order sliding mode observer(5h& ذ-` ا-?*ا#c ذو ا-%?t ا-?%7h r-s-9 ا-*g=) . -=%7ء ھ,p3 د>7a r,>v493,67%@,) ا-?*ا#=) ا-<2>) y#26 ا-?y#26( ، ^=3 ا-?3=^(5h& ذ-` y6 ا7kرة وا\&ة q6 ا-%/7م e46*h ). output(?5*وف 4f6 y6<7ت ا-?j*ج ا-ب ا-q6 pe q,?j4*,m ig7% ا;o+*ا eh 2بm*6 y#26 (>\k?h 2م><)desired piston position ( t,"h *+,"6 r<*ط qh)simple output feedback ( ءs1 7ءx-5& اh `-وذ . ا;o+*اب khوة rbh ذ-` quن . ;1=7ر y#26 ا-?2m*6 y#26 y=44^=3ب output feedback (eh(ا-*#?,) z/g* اداء 6?74ز -b?",+* ا-?<4*ح :im74 ا-?7e7vة q3?< 76 p#وف ا*s?-3! اv4-ا &z1. al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 6, no. 1, pp 69-79 (2010) the effect of mechanical combined contact stress with buckling load on the stress distribution in the ball and socket joint mechanism fathi al shamaa fatima salman department of mechanical engineering/ college of engineering/ university of baghdad (received 30 april 2008; accepted 17 september 2009) abstract the design of components subjected to contact stress as local compressive stress is important in engineering application especially in ball and socket joining. two kinds of contact stress are introduced in the ball and socket joint, the first is from normal contact while the other is from sliding contact. although joining two long links (drive shaft in steering cars) will cause the effect of flexural and tensional buckling stress in hollow columns through the ball and socket ends on the failure condition of the joining mechanism. in this paper the consideration of the combined effect of buckling load and contact stress on the ball and socket joints have been taken, epically on the stress distribution in the contact area. different parameters have been taken in the design of joint. this is done by changing the angles for applied loads with the principle axis, the angle of contact between ball and socket and using different applied loads. the problem has been solved using analytical solution for computing the critical loads and using these loads for calculating the stress distribution with finite element method using ansys 10. the numerical results have been compared with the experimental method using photo elasticity pattern which shows good agreement between experimental and simulation results. keywords: joining, contact stress, ball and socket, buckling stress, sliding contact stress 1. introduction two major problems are introduced in the designing of joints. 1) to find the suitable length and cross sectional area for the two rods which must be jointed. 2) the kind of the joint that can sustain the condition of loading which is applied at these two rods. the first problem must be solved by calculating the buckling stresses in long rods that are subjected to compressive load. some time failure by buckling is reached before the yield stress in compression. the buckling occurs owing to one or more of the following reason: a) the strut may not be perfectly straight b) the load may not be applied exactly along the axis. c) one part of the material may yield in compression more than the others. the second problem depends on the value of the contact stress in the end of the joints. the local compressive contact stress between two joining surfaces lead to infinite values which must be avoided by increasing the bearing area reducing the value of the compressive stress to some finite value . the use of the ball and socket joints for driving members has increased considerably over the last 20 years due to their ease of use and speed of installation (i.e. the drive shaft in steering system of the automobile) which needs more suitable joint. most of the work concentrated on determining the critical load that caused failure to the joint with different boundary conditions. carretero j. a. et al [1] utilized two and three degree of freedom joints to connect the robot arms, with universal joints commonly used for the 2 degree of freedom joints they have led to practical implementation of spherical joints mechanism. alecp. robertson et al [2] have developed a spherical joints based on a ball and fathi al shamma al-khwarizmi engineering journal, vol. 6, no. 1, pp 69 -79 (2010) 70 socket configuration for parallel kinematic machines; four prototypes are implemented using point, rolling sliding contact mechanism between the ball and the socket. foully a. mohamad et .al [3] have stated the effect of bulging and buckling stresses on the defects concentrated in wall splitting of ball and socket joint; they also stated the influence of the ratio of ball diameter to the thickness of the flang on the radial flanging force and on the failure of the joint. erin renee roberts [4] used finite element software package which calculated the elastic flexural torsional buckling load of plane frame. this program is refractory into object -oriented design to improve the structure of the soft ware and increase its flexibility. f. liu. et al [5] analyzed the stress distribution and the transientelasto hydrodynamic lubrication for typical metal – on metal bearing under dynamic operation condition of load and sped for ball and socket joints . in this research, the combined effect of buckling stress with the contact stresses on the stress distribution in ball and socket joint. this analysis have accomplished numerically using finite element method ansys (10) comparing the experiment methods using photo elasticity. the objective of this paper is to find the critical loads from combined buckling and contact stresses which causes failure to the joint under complex condition and then to apply these loads to the region of high stress and solve them using finite element method ansys (10) and compare the results with the experimental one using photo elasticity pattern for ball and socket joint . 2. theoretical analysis (i) normal buckling stress the global (euler) mode occurs in slender columns and involves sudden lateral deflection without deformation of the cross section. the euler buckling equation is (10): … (1) where ei is the bending stiffness, (l) is column length, k is the end restraint coefficient. when the length of the column is such, the predicted local and global loads are close to the experimental failure loads, which are lower than the theoretical prediction. an empirical equation was proposed by barbero et al (q) (2000); the column buckling load is predicted as pc = ki pl … (2) where: … (3) c is the empirical interaction constant adjusted to fit data determined from column test [9]. … (4) the average buckling stress for a pin – ended column is: … (5) where a is the cross sectional area (ii) lateral bucking area the end supports of beam allow rotation in the plan of depth but restrict displacement of the beam ends under unstable conditions as shown in fig. (1), the compressive side of beam depth will be laterally displaced. the beam is subjected to bending moment mx = mo cos φ , my = mo sin φ and twisting moment mt = mo cos φ sin φ as shown in fig (2) from (11) … (6) which yields from the boundary condition at z=0: u =0 and φ = 0 , at z = l : u = 0 and φ = 0 gives: … (7) and from equation ( 7 ), the stress lateral backling causes a tension equal to : (mt)max = moψ = mou max … (8) … (9) fathi al shamma al-khwarizmi engineering journal, vol. 6, no. 1, pp 69 -79 (2010) 71 (a) (b) fig.1. lateral bucking of a thin beam in bending. socket – fixed ball – fixed (a) ball – fixed and socket – fixed configuration. (b) free body diagram of ball forces the preload force fp acts along the socket axis. fig.2. illustration of applied loading and moment at the end of the lever. fathi al shamma al-khwarizmi engineering journal, vol. 6, no. 1, pp 69 -79 (2010) 72 (iii) combined normal and lateral stress for elastic condition under combined normal and shear stress, and by using σt = σ1 + σ2 tresca yields criteria for the elastic failure so that the proper load of pc must be suitable for combined lateral and bending backling. (iv) contact stress normal contact stresses the general solution in the case of asymmetrical complete contact over the range -b ≤ x ≤ b as shown in fig ( 2 ) and is given by (12) inverse of the singular integral equation : … (10) where: for hertzien case (v) partial slip contact in particular, the normal load p will cause normal contact while the tangential force q will cause sliding and slip contact. this analysis is applied only to the case where the contact arises between elastically similar components. an integral equation is to be considered which relates the displacement parallel with surface to the surface tractions (ref 7) is to be considered: … (11) where: g(x) is the relative tangential displacement of surface particles. then tangential equilibrium will be satisfied if … (12) the contact area ( l ) , is affected by the position of the applied normal load which has an angle θ with respect to the main axis of the ball joint represented when we find the critical load (pc) and the contact angle (γ) which have an effect on the contact area between the clamped rod and the ball joint which varies between 180o → 270o as shown in fig. (2); then this effect will reduce the partial slip contact. this problem made the contact area l very complicated, and to solve it, the value of θ obtained from eq. (12) with normal contact load p(x) must not exceed the shear yield stress of the ball and socket joint material. (vi) accuracy of the mathematical model two effects have been pronounced in the mathematical model that must be solved in this research. 1. the general solution in the case of asymmetrical complete contact is given by the equation of mushkelishili's which differs from hertizian contact law and more complicated because the integral boundary condition at both p(b) and p(-b) must be zero which reduces the general solutions for a contact over the range –b ≤ x ≤ b . this can be revived with hertizian pressure for a completed contact i.e. in the case a/b = 0 while with a/b > 0 then the pressure in this case will be affected by the forces of the slip contact with the buckling load which will increase the slip contact rather than the normal contact which causes fatling of the contact area. the pressure distribution will be higher than the hertizian pressure especially for the inclined load with y axis which causes failure in this region. 2. the second difficult in the theoretical calculation is to find the critical buckling load which is either from banding buckling or shearing buckling and this depends on the cross sectional area of the column and in the ratio of the length of the rod to the width of the flatning end of the joint; it can be seen that the critical buckling land will be caused by shearing buckling rather than by bending buckling which will increase the slip contact and decrease the normal contact so that the fathi al shamma al-khwarizmi engineering journal, vol. 6, no. 1, pp 69 -79 (2010) 73 values of pressure distribution have values higher than that of hertizian law and more suitable to the stress distribution . (vii) finite element analysis the ansys finite element analysis (fea) program offers variety of elements designed to treat cases of changing mechanical contact between the parts of different faces that cannot be assumed negligible. there is a number of steps in the solution procedure using the finite element packages which require the user to go through these step as shown in fig (3). contact elements can be grouped into four general categories based on increasing the levels of sophistication of complexity apoint to point gup elements bpoint to line ( or slide line ) contact element cpoint to surface contact elements dsurface to surface contact elements to optimize the simulations, parametric study is needed during the study different element types, element sizes, sheet length have been tried. the main objective in this effort is to reduce the required cpu time in the (ansys 10) solution. ansys mechanical interactive sleet element 1 plane 2d 182 2 contac 172 3 target 169 select real constant for contact element select material property in elastic state for the ball and socket great the modelgeometrics (two circular contact joint) mesh the areas with asu1table grid set the boundary condition for sliding and buckling analysis options great the load step files from the theoretical analysis solve the problem to find the stress distribution with different angle of contact finish 3. experimental method in this study, design of ball and socket joint is analyzed. they have been modeled and described under different type of loading, angle of contact and different shapes. the models of three types of contact angles 180°, 220° , 270° manufactured from sheets of epoxy resin my 750 photo elastic material which has fringe constant 0.44 [ m pa / ( fr / mm) ] circumferential ball and socket joint . the models wave machined from proto type preparation using milling machine. the profile and external dimensions are all exactly 2.5 times the size of the original to facilitate handling and data collection. this model was a two dimensional component as the loading required for these models to be axially , -10 °, -20°than special loading frame required. after the first loading , the ball and socket of the specimen was placed in a dark field circular which has been used to view in plane polaris cope and the point is located by rotating the ball with fixed socket until the isoclinic contour is perpendicular to the contact face . the point at which this occurred was marked and the ball and socket were removed from the poloriscope and then it was repeated for another loading. 4. discussion of results in this research the results illustrate the variation of the normal contact stress which has been solved by ansys 10 with different loading. the sample used in the numerical and experimental procedure is a ball joint of a radius equal (5 cm) and a socket of width (2 cm) and length (20 cm). all the applied load is on the fixed ball and the moving socket at angle 10°, and 20° as shown in fig (l). it can be seen that with increasing the angle of the applied load, the normal stress will be decreased. also it can be seen from fig (2) that the variation of slip contact stress with different loading and the behavior of the slip contact stress which increases with increasing the angle φ. these two effect of contact stresses will give different values when combined with the buckling stress which increased very high at angle φ = 20. figures 4 to 9 it show increasing in the value of normal contact stress with increasing the angle of contact of 180° , 220° and 270°. the sliding contact stress will have max effect at 270 ° and this is because the value of contact stress will be affected by this reduction. figures (13) and (14) illustrate the experimental results of combined contact and fathi al shamma al-khwarizmi engineering journal, vol. 6, no. 1, pp 69 -79 (2010) 74 buckling stress with the applied load sat 180° and 270° which shows good agreement with the numerical one. load (10 n), φ = 180º load (10 n), φ = 180º load (10 n), φ = 220º load (10 n), φ = 220º load (10 n), φ = 270º load (10 n), φ = 270º fig. 3. the experimental results of ansys 10 for the pattern of contact angle 180o, 220o and 270o respectively. fathi al shamma al-khwarizmi engineering journal, vol. 6, no. 1, pp 69 -79 (2010) 75 load (1.5 n), φ = 0 load (1.5 n), φ = 0 load (2 n), φ = 10 load (2 n), φ = 10 load (1n), φ = 20 load (1n), φ = 20 light dark fig.4. shows the experimental photo elasticity pattern using light and dark field to show the normal and shear slip stresses in different contact angle. fathi al shamma al-khwarizmi engineering journal, vol. 6, no. 1, pp 69 -79 (2010) 76 ф=0 ф=10 ф=20 0 20 40 60 80 100 120 140 0.5 1 1.5 2 s t r e s s e s (m p a ) 0 fig.5. the variation of normal contact stress numerically with the loading at 180° angle of contact. fig.6. the variation of slip contact stress numerically with the loading at 180° angle of contact. fig.7. the variation of combined contact and buckling stress numerically with the loading at 180° angle of contact. fig.8. the variation of normal contact stress numerically with the loading at 220° angle of contact. fig.9. the variation of slip contact stress numerically with the loading at 220° angle of contact. fig.10. the variation of combined contact stress numerically with the loading at 270° angle of contact. 0 10 20 30 40 0.5 1 1.5 2 loading (kn) c o m b in d c o n ta c t a n d b u c k lin g s tr e s s ( m p a ) ф=0 ф=10 ф=20 0 50 100 150 0.5 1 1.5 2 loading (kn) c o m b in d c o n ta c t s tr e s s (m p a ) ф=0 ф=10 ф=20 0 10 20 30 40 0.5 1 1.5 2 loading(kn) s lip c o n ta c t s tr e s s ( m p a ) ф=0 ф=10 ф=20 0 10 20 30 40 0.5 1 1.5 2 loading (kn) s lip c o n ta c t s tr e s s ( m p a ) ф=0 ф=10 ф=20 0.5 1 1.5 2 s t r e s s e s (m p a ) 0 0 20 40 60 80 100 120 140 ф=0 ф=10 ф=20 fathi al shamma al-khwarizmi engineering journal, vol. 6, no. 1, pp 69 -79 (2010) 77 fig.11. the variation of normal contact stress numerically with the loading at 270° angle of contact. fig.12. the variation of slip contact stress numerically with the loading at 270° angle of contact. fig.13. the variation of combined contact and buckling stress numerically with the loading at 270° angle of contact. fig.14. the variation of combined and buckling stresses experimentally with the applied loading at 180° angle of contact. fig.15. the variation of combined and buckling stresses experimentally with the applied loading at 270° angle of contact. 5. conclusions the problem of ball and socket joint failure with combined effect of buckling and contact stresses has been studied, giving results for surface traction and interior stress field induced by contact. this research was solved numerically using ansys (10 ) and the results were compared with the experimental one using photo elasticity which gives good illustration about stress distribution and the effect of sliding and normal contact on the length of the joining rods at different angle of contact. the numerical results give good agreement with the experimental one. the results show that the buckling load in the ball joint will be affected on the contact pressure distribution which causes the shear buckling to flatten the contact area of the joint and this causes the pressure distribution to be higher than the horizontal pressure. the angle of inclination of the contact rod with the ball joint will increase under large inclined angle of the rod and this causes the 0 10 20 30 40 50 0.5 1 1.5 2 loading (kn) s lip c o n ta c t s tr e s s ( m p a ) ф=0 ф=10 ф=20 0 20 40 60 80 100 120 140 0.5 1 1.5 2 loading (kn) c o m b in d c o n ta c t a n d b u c k lin g s tr e s s ( m p a ) ф=0 ф=10 ф=20 0 50 100 150 0.5 1 1.5 2 loading (kn) c o m b in e d c o n t a c t a n d b u c k l in g s t r e s s e s (m p a ) ф=0 ф=10 ф=20 0 20 40 60 80 100 120 140 ф=0 ф=10 ф=20 0.5 1 1.5 2 s t r e s s e s (m p a ) 0 0 50 100 150 0.5 1 1.5 2 loading (kn) c o m b in e d c o n t a c t a n d b u c k l in g s t r e s s ( m p a ) ф=20 ф=10 ф=0 fathi al shamma al-khwarizmi engineering journal, vol. 6, no. 1, pp 69 -79 (2010) 78 pressure distribution of the contact area to double more than the value of the hertizian law. nomenclature ei young's modulus of body i n / m2 i second moment of area m4 k the end restraint coefficient l column length m g modulus of rigidity n / m2 a cross sectional area mm2 pl short – column load n c empirical interaction constant (mo)cr the critical end bending moment nm σ1 normal bucking stress m la mt the twisting moment n.m τmax the maximum tensional shear stress at umax mpa σ2 the stress of lateral bucking mpa σy yield stress of the joint material mpa l contact area related to the geometry of the contacting surfaces mm2 a the straight part of punch boundary length mm b the end of the contact length ( b ≤ x ≤ -b ) mm the slope at each point of the profile of the ball joint flaunting t a small region from the contact length specified by the angle ψ r the corners arc of contact mm b lundurs second constant which is equal to zero to elastically similar contact q slip shearing traction force n q tangential shearing force n 6. reference [1] carretero j apodorodeski rp,nahon ma. gosselincm.kinematic “analysis and optimization of a new three –degree of – freedom spatial parallel manipulator “. asme j mech des 2000, 122(1): 17-24 [2] aleep. robertson and alexander h.slocum "measurement and characterization of precision spherical joint”. [3] foully a. mohammed, samy zein el –abden, mohi eldeen abdel – rahman, " a rotary flange , forming process on the lath using a ball –shaped ,mater. process .technol, 2004. [4] erin renee roberts, (2002) " elastic flexuraltorsional buckling analysis using finite element method" . university of pittsburghat johnstown. [5] f.liu, z.m.jin,f.hirt, c.rieker, p. roberts and p.grigoris . “transient elasto hydrodynamic lubrication analysis of metal – onmetal hip implautunder simulated walking conditions. [6] ansys inc v 10’, ' ansys manual, 2005. [7] e.j. hearn, (1985) "mechanics of material", vol. 2, pergamon press comp, london and northampton. [8] mc master – carr , catalog , 473 ridge road , dayton , nj08810 , usa , 2000 . [9] barbero, e.j., dede, e and jones, s., “experimental verification of bucking mode interaction in intermediate length columns ", i. j. solid structures, 2000. [10] s. timoshinko , " theory of elasticity stability " , 1975 . [11] abdel – rahman ragab, salah eldin bayoumi, " engineering solid mechanics fundamentals and applications " . crc press llc, 2000. [12] m. ciavarella, d.a hills and g. monno, “the influence of rounded edges on indentation by a flat punch “. proc. inst. mech. engrs. vol 212 partc p 319, 1998. )2010( 79–69، صفحة 1، العدد 6مجلة الخوارزمي الھندسیة المجلد فتحي الشماع 79 اج على توزیع اإلجھادات التأثیر المیكانیكي المشترك إلجھادات وأحمال االنبع في المفصل نوع الكرة والمقبض فاطمة سلمان عفتحي الشما جامعة بغداد/ ھكلیة الھندس/ ھندسة المیكانیكقسم الخالصة دًا ًا ج ون مھم غوطة یك عیة المض ادات الموض ل اإلجھ عي مث س موض اد تالم ى إجھ یة إن تصمیم األجزاء المیكانیكیة التي تخضع إل ات الھندس ي التطبیق ف بض رة والمق وع الك ر . وخصوصًا في المفاصل ن ودي واآلخ تالمس العم بض ، األول ال رة والمق ل الك ي مفص ر ف تالمس تظھ ادات ال ن إجھ وعین م اك ن وھن . التالمس اإلنزالقي یارة (خصوصًا عند ربط موصلین طویلین ود الس ي مق دویر ف رن ) كما في عمود الت أثیر الم بب الت ة یس دة المجوف ي األعم وائي ف اج االلت ادات االنبع وإجھ . خالل نھایات الكرة والمقبض إلى فشل آلیة الربط المیكانیكیة ة ي منطق ادات ف تالمس ھذا البحث أخذ بنظر االعتبار التأثیر المشترك لحمل االنبعاج وإجھادات التالمس في مفصل الكرة والمقبض على توزیع اإلجھ . ال . خذت في تصمیم المفصل وذلك بتغییر زاویة األحمال المسلطة مع المحور األساسي وباستخدام أحمال مسلطة مختلفةرموز مختلفة أ ع اب توزی ال لحس ذه األحم تخدام ھ تالمس واس ادات ھذه المشكلة عولجت باستخدام الحلول التحلیلیة بحساب األحمال الحرجة من عملیة االنبعاج وال اإلجھ . تطابق جید بینھم النتائج العددیة قورنت مع النتائج العملیة باستخدام جھاز تحلیل اإلجھادات وأظھرت. (ansys 10) لمتطورةا طریقةالباستخدام 0 50 100 150 0.511.52 loading (kn) combined contact and buckling stresses(mpa) ф=0 ф=10 ф=20 0 20 40 60 80 100 120 140 0.511.52 loading (kn) combind contact and buckling stress (mpa) ф=0 ф=10 ф=20 0 10 20 30 40 50 0.511.52 loading (kn) slip contact stress (mpa) ф=0 ф=10 ф=20 0 10 20 30 40 0.511.52 loading (kn) combind contact and buckling stress (mpa) ф=0 ф=10 ф=20 0 10 20 30 40 0.511.52 loading (kn) slip contact stress (mpa) ф=0 ф=10 ф=20 0 50 100 150 0.511.52 loading (kn) combind contact stress (mpa) ф=0 ф=10 ф=20 0 10 20 30 40 0.511.52 loading(kn) slip contact stress (mpa) ф=0 ф=10 ф=20 0 50 100 150 0.511.52 loading (kn) combined contact and buckling stress (mpa) ф=20 ф=10 ф=0 fathi al shamma al-khwarizmi engineering journal, vol. 6, no. 1, pp 69 -79 (2010) al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 6, no. 1, pp 69-79 (2010) the effect of mechanical combined contact stress with buckling load on the stress distribution in the ball and socket joint mechanism fathi al shamaa fatima salman department of mechanical engineering/ college of engineering/ university of baghdad (received 30 april 2008; accepted 17 september 2009) abstract the design of components subjected to contact stress as local compressive stress is important in engineering application especially in ball and socket joining. two kinds of contact stress are introduced in the ball and socket joint, the first is from normal contact while the other is from sliding contact. although joining two long links (drive shaft in steering cars) will cause the effect of flexural and tensional buckling stress in hollow columns through the ball and socket ends on the failure condition of the joining mechanism. in this paper the consideration of the combined effect of buckling load and contact stress on the ball and socket joints have been taken, epically on the stress distribution in the contact area. different parameters have been taken in the design of joint. this is done by changing the angles for applied loads with the principle axis, the angle of contact between ball and socket and using different applied loads. the problem has been solved using analytical solution for computing the critical loads and using these loads for calculating the stress distribution with finite element method using ansys 10. the numerical results have been compared with the experimental method using photo elasticity pattern which shows good agreement between experimental and simulation results. keywords: joining, contact stress, ball and socket, buckling stress, sliding contact stress 1. introduction two major problems are introduced in the designing of joints. 1) to find the suitable length and cross sectional area for the two rods which must be jointed. 2) the kind of the joint that can sustain the condition of loading which is applied at these two rods. the first problem must be solved by calculating the buckling stresses in long rods that are subjected to compressive load. some time failure by buckling is reached before the yield stress in compression. the buckling occurs owing to one or more of the following reason: a) the strut may not be perfectly straight b) the load may not be applied exactly along the axis. c) one part of the material may yield in compression more than the others. the second problem depends on the value of the contact stress in the end of the joints. the local compressive contact stress between two joining surfaces lead to infinite values which must be avoided by increasing the bearing area reducing the value of the compressive stress to some finite value . the use of the ball and socket joints for driving members has increased considerably over the last 20 years due to their ease of use and speed of installation (i.e. the drive shaft in steering system of the automobile) which needs more suitable joint. most of the work concentrated on determining the critical load that caused failure to the joint with different boundary conditions. carretero j. a. et al [1] utilized two and three degree of freedom joints to connect the robot arms, with universal joints commonly used for the 2 degree of freedom joints they have led to practical implementation of spherical joints mechanism. alecp. robertson et al [2] have developed a spherical joints based on a ball and socket configuration for parallel kinematic machines; four prototypes are implemented using point, rolling sliding contact mechanism between the ball and the socket. foully a. mohamad et .al [3] have stated the effect of bulging and buckling stresses on the defects concentrated in wall splitting of ball and socket joint; they also stated the influence of the ratio of ball diameter to the thickness of the flang on the radial flanging force and on the failure of the joint. erin renee roberts [4] used finite element software package which calculated the elastic flexural torsional buckling load of plane frame. this program is refractory into object -oriented design to improve the structure of the soft ware and increase its flexibility. f. liu. et al [5] analyzed the stress distribution and the transient-elasto hydrodynamic lubrication for typical metal – on metal bearing under dynamic operation condition of load and sped for ball and socket joints . in this research, the combined effect of buckling stress with the contact stresses on the stress distribution in ball and socket joint. this analysis have accomplished numerically using finite element method ansys (10) comparing the experiment methods using photo elasticity. the objective of this paper is to find the critical loads from combined buckling and contact stresses which causes failure to the joint under complex condition and then to apply these loads to the region of high stress and solve them using finite element method ansys (10) and compare the results with the experimental one using photo elasticity pattern for ball and socket joint . 2. theoretical analysis (i) normal buckling stress the global (euler) mode occurs in slender columns and involves sudden lateral deflection without deformation of the cross section. the euler buckling equation is (10): … (1) where ei is the bending stiffness, (l) is column length, k is the end restraint coefficient. when the length of the column is such, the predicted local and global loads are close to the experimental failure loads, which are lower than the theoretical prediction. an empirical equation was proposed by barbero et al (q) (2000); the column buckling load is predicted as pc = ki pl … (2) where: … (3) c is the empirical interaction constant adjusted to fit data determined from column test [9]. … (4) the average buckling stress for a pin – ended column is: … (5) where a is the cross sectional area (ii) lateral bucking area the end supports of beam allow rotation in the plan of depth but restrict displacement of the beam ends under unstable conditions as shown in fig. (1), the compressive side of beam depth will be laterally displaced. the beam is subjected to bending moment mx = mo cos φ , my = mo sin φ and twisting moment mt = mo cos φ sin φ as shown in fig (2) from (11) … (6) which yields from the boundary condition at z=0: u =0 and φ = 0 , at z = l : u = 0 and φ = 0 gives: … (7) and from equation ( 7 ), the stress lateral backling causes a tension equal to : (mt)max = moψ = mou max … (8) … (9) (a) (b) fig.1. lateral bucking of a thin beam in bending. socket – fixed ball – fixed (a) ball – fixed and socket – fixed configuration. (b) free body diagram of ball forces the preload force fp acts along the socket axis. fig.2. illustration of applied loading and moment at the end of the lever. (iii) combined normal and lateral stress for elastic condition under combined normal and shear stress, and by using σt = σ1 + σ2 tresca yields criteria for the elastic failure so that the proper load of pc must be suitable for combined lateral and bending backling. (iv) contact stress normal contact stresses the general solution in the case of asymmetrical complete contact over the range -b ≤ x ≤ b as shown in fig ( 2 ) and is given by (12) inverse of the singular integral equation : … (10) where: for hertzien case (v) partial slip contact in particular, the normal load p will cause normal contact while the tangential force q will cause sliding and slip contact. this analysis is applied only to the case where the contact arises between elastically similar components. an integral equation is to be considered which relates the displacement parallel with surface to the surface tractions (ref 7) is to be considered: … (11) where: g(x) is the relative tangential displacement of surface particles. then tangential equilibrium will be satisfied if … (12) the contact area ( l ) , is affected by the position of the applied normal load which has an angle θ with respect to the main axis of the ball joint represented when we find the critical load (pc) and the contact angle (γ) which have an effect on the contact area between the clamped rod and the ball joint which varies between 180o → 270o as shown in fig. (2); then this effect will reduce the partial slip contact. this problem made the contact area l very complicated, and to solve it, the value of θ obtained from eq. (12) with normal contact load p(x) must not exceed the shear yield stress of the ball and socket joint material. (vi) accuracy of the mathematical model two effects have been pronounced in the mathematical model that must be solved in this research. 1. the general solution in the case of asymmetrical complete contact is given by the equation of mushkelishili's which differs from hertizian contact law and more complicated because the integral boundary condition at both p(b) and p(-b) must be zero which reduces the general solutions for a contact over the range –b ≤ x ≤ b . this can be revived with hertizian pressure for a completed contact i.e. in the case a/b = 0 while with a/b > 0 then the pressure in this case will be affected by the forces of the slip contact with the buckling load which will increase the slip contact rather than the normal contact which causes fatling of the contact area. the pressure distribution will be higher than the hertizian pressure especially for the inclined load with y axis which causes failure in this region. 2. the second difficult in the theoretical calculation is to find the critical buckling load which is either from banding buckling or shearing buckling and this depends on the cross sectional area of the column and in the ratio of the length of the rod to the width of the flatning end of the joint; it can be seen that the critical buckling land will be caused by shearing buckling rather than by bending buckling which will increase the slip contact and decrease the normal contact so that the values of pressure distribution have values higher than that of hertizian law and more suitable to the stress distribution . (vii) finite element analysis the ansys finite element analysis (fea) program offers variety of elements designed to treat cases of changing mechanical contact between the parts of different faces that cannot be assumed negligible. there is a number of steps in the solution procedure using the finite element packages which require the user to go through these step as shown in fig (3). contact elements can be grouped into four general categories based on increasing the levels of sophistication of complexity apoint to point gup elements bpoint to line ( or slide line ) contact element c point to surface contact elements dsurface to surface contact elements to optimize the simulations, parametric study is needed during the study different element types, element sizes, sheet length have been tried. the main objective in this effort is to reduce the required cpu time in the (ansys 10) solution. ansys mechanical interactive sleet element 1 plane 2d 182 2 contac 172 3 target 169 select real constant for contact element select material property in elastic state for the ball and socket great the modelgeometrics (two circular contact joint) mesh the areas with asu1table grid set the boundary condition for sliding and buckling analysis options great the load step files from the theoretical analysis solve the problem to find the stress distribution with different angle of contact finish 3. experimental method in this study, design of ball and socket joint is analyzed. they have been modeled and described under different type of loading, angle of contact and different shapes. the models of three types of contact angles 180°, 220° , 270° manufactured from sheets of epoxy resin my 750 photo elastic material which has fringe constant 0.44 [ m pa / ( fr / mm) ] circumferential ball and socket joint . the models wave machined from proto type preparation using milling machine. the profile and external dimensions are all exactly 2.5 times the size of the original to facilitate handling and data collection. this model was a two dimensional component as the loading required for these models to be axially , -10 °, -20°than special loading frame required. after the first loading , the ball and socket of the specimen was placed in a dark field circular which has been used to view in plane polaris cope and the point is located by rotating the ball with fixed socket until the isoclinic contour is perpendicular to the contact face . the point at which this occurred was marked and the ball and socket were removed from the poloriscope and then it was repeated for another loading. 4. discussion of results in this research the results illustrate the variation of the normal contact stress which has been solved by ansys 10 with different loading. the sample used in the numerical and experimental procedure is a ball joint of a radius equal (5 cm) and a socket of width (2 cm) and length (20 cm). all the applied load is on the fixed ball and the moving socket at angle 10°, and 20° as shown in fig (l). it can be seen that with increasing the angle of the applied load, the normal stress will be decreased. also it can be seen from fig (2) that the variation of slip contact stress with different loading and the behavior of the slip contact stress which increases with increasing the angle φ. these two effect of contact stresses will give different values when combined with the buckling stress which increased very high at angle φ = 20. figures 4 to 9 it show increasing in the value of normal contact stress with increasing the angle of contact of 180° , 220° and 270°. the sliding contact stress will have max effect at 270 ° and this is because the value of contact stress will be affected by this reduction. figures (13) and (14) illustrate the experimental results of combined contact and buckling stress with the applied load sat 180° and 270° which shows good agreement with the numerical one. load (10 n), φ = 180º load (10 n), φ = 180º load (10 n), φ = 220º load (10 n), φ = 220º load (10 n), φ = 270º load (10 n), φ = 270º fig. 3. the experimental results of ansys 10 for the pattern of contact angle 180o, 220o and 270o respectively. load (1.5 n), φ = 0 load (1.5 n), φ = 0 load (2 n), φ = 10 load (2 n), φ = 10 load (1n), φ = 20 load (1n), φ = 20 light dark fig.4. shows the experimental photo elasticity pattern using light and dark field to show the normal and shear slip stresses in different contact angle. fig.5. the variation of normal contact stress numerically with the loading at 180° angle of contact. fig.6. the variation of slip contact stress numerically with the loading at 180° angle of contact. fig.7. the variation of combined contact and buckling stress numerically with the loading at 180° angle of contact. fig.8. the variation of normal contact stress numerically with the loading at 220° angle of contact. fig.9. the variation of slip contact stress numerically with the loading at 220° angle of contact. fig.10. the variation of combined contact stress numerically with the loading at 270° angle of contact. fig.11. the variation of normal contact stress numerically with the loading at 270° angle of contact. fig.12. the variation of slip contact stress numerically with the loading at 270° angle of contact. fig.13. the variation of combined contact and buckling stress numerically with the loading at 270° angle of contact. fig.14. the variation of combined and buckling stresses experimentally with the applied loading at 180° angle of contact. fig.15. the variation of combined and buckling stresses experimentally with the applied loading at 270° angle of contact. 5. conclusions the problem of ball and socket joint failure with combined effect of buckling and contact stresses has been studied, giving results for surface traction and interior stress field induced by contact. this research was solved numerically using ansys (10 ) and the results were compared with the experimental one using photo elasticity which gives good illustration about stress distribution and the effect of sliding and normal contact on the length of the joining rods at different angle of contact. the numerical results give good agreement with the experimental one. the results show that the buckling load in the ball joint will be affected on the contact pressure distribution which causes the shear buckling to flatten the contact area of the joint and this causes the pressure distribution to be higher than the horizontal pressure. the angle of inclination of the contact rod with the ball joint will increase under large inclined angle of the rod and this causes the pressure distribution of the contact area to double more than the value of the hertizian law. nomenclature ei young's modulus of body i n / m2 i second moment of area m4 k the end restraint coefficient l column length m g modulus of rigidity n / m2 a cross sectional area mm2 pl short – column load n c empirical interaction constant (mo)cr the critical end bending moment nm σ1 normal bucking stress m la mt the twisting moment n.m τmax the maximum tensional shear stress at umax mpa σ2 the stress of lateral bucking mpa σy yield stress of the joint material mpa l contact area related to the geometry of the contacting surfaces mm2 a the straight part of punch boundary length mm b the end of the contact length ( b ≤ x ≤ -b ) mm the slope at each point of the profile of the ball joint flaunting t a small region from the contact length specified by the angle ψ r the corners arc of contact mm b lundurs second constant which is equal to zero to elastically similar contact q slip shearing traction force n q tangential shearing force n 6. reference [1] carretero j apodorodeski rp,nahon ma. gosselincm.kinematic “analysis and optimization of a new three –degree of – freedom spatial parallel manipulator “. asme j mech des 2000, 122(1): 17-24 [2] aleep. robertson and alexander h.slocum "measurement and characterization of precision spherical joint”. [3] foully a. mohammed, samy zein el –abden, mohi eldeen abdel – rahman, " a rotary flange , forming process on the lath using a ball –shaped ,mater. process .technol, 2004. [4] erin renee roberts, (2002) " elastic flexuraltorsional buckling analysis using finite element method" . university of pittsburghat johnstown. [5] f.liu, z.m.jin,f.hirt, c.rieker, p. roberts and p.grigoris . “transient elasto hydrodynamic lubrication analysis of metal – onmetal hip implautunder simulated walking conditions. [6] ansys inc v 10’, ' ansys manual, 2005. [7] e.j. hearn, (1985) "mechanics of material", vol. 2, pergamon press comp, london and northampton. [8] mc master – carr , catalog , 473 ridge road , dayton , nj08810 , usa , 2000 . [9] barbero, e.j., dede, e and jones, s., “experimental verification of bucking mode interaction in intermediate length columns ", i. j. solid structures, 2000. [10] s. timoshinko , " theory of elasticity stability " , 1975 . [11] abdel – rahman ragab, salah eldin bayoumi, " engineering solid mechanics fundamentals and applications " . crc press llc, 2000. [12] m. ciavarella, d.a hills and g. monno, “the influence of rounded edges on indentation by a flat punch “. proc. inst. mech. engrs. vol 212 partc p 319, 1998. التأثير الميكانيكي المشترك لإجهادات وأحمال الانبعاج على توزيع الإجهادات في المفصل نوع الكرة والمقبض فتحي الشماع فاطمة سلمان قسم هندسة الميكانيك/ كلية الهندسه/ جامعة بغداد الخلاصة إن تصميم الأجزاء الميكانيكية التي تخضع إلى إجهاد تلامس موضعي مثل الإجهادات الموضعية المضغوطة يكون مهماً جداً في التطبيقات الهندسية وخصوصاً في المفاصل نوع الكرة والمقبض . وهناك نوعين من إجهادات التلامس تظهر في مفصل الكرة والمقبض ، الأول التلامس العمودي والآخر التلامس الإنزلاقي. خصوصاً عند ربط موصلين طويلين (كما في عمود التدوير في مقود السيارة) يسبب التأثير المرن وإجهادات الانبعاج الالتوائي في الأعمدة المجوفة خلال نهايات الكرة والمقبض إلى فشل آلية الربط الميكانيكية . هذا البحث أخذ بنظر الاعتبار التأثير المشترك لحمل الانبعاج وإجهادات التلامس في مفصل الكرة والمقبض على توزيع الإجهادات في منطقة التلامس . رموز مختلفة أخذت في تصميم المفصل وذلك بتغيير زاوية الأحمال المسلطة مع المحور الأساسي وباستخدام أحمال مسلطة مختلفة. هذه المشكلة عولجت باستخدام الحلول التحليلية بحساب الأحمال الحرجة من عملية الانبعاج والتلامس واستخدام هذه الأحمال لحساب توزيع الإجهادات باستخدام الطريقة المتطورة (ansys 10) . النتائج العددية قورنت مع النتائج العملية باستخدام جهاز تحليل الإجهادات وأظهرت تطابق جيد بينهم. � embed pbrush ��� 79 _1173207870 96-101 al-khwarizmi engineering journal,vol. 11, no. tensile and compressive properties of kaolin rienforced epoxy department of (received abstract the toughening of epoxy resins with the addition of organic or inorganic compounds is of great interest nowadays, considering their large scale of applications particles having different particle sizes as reinforcement. weight %) of kaolin was prepared by using hand lay method elasticity, yield, tensile, and compressive strength with filler content was evaluated. the comp modulus of elasticity and compressive composites decreases with rising kaolin content. particle size in all cases. keywords: mechanical properties, composite materials 1. introduction particles filled polymer composites have become attractive because of their wide applications and low cost. incorporating inorganic mineral fillers into plastic resin improves various mechanical and physical properties of the materials such as mechanical strength, and heat deflection temperature. in general the mechanical properties of particulate filled polymer composites depend strongly on size, shape and distribution of filler particles in the matrix polymer and good adhesion at the interface surface. epoxy resin is widely used as a substrate material in electronic packaging industry. as one of the most widely used thermosetting resin, epoxy resin possess special chemical characteristics such as little or no by volatiles formation upon curing, low shrinkage, can be cured over a wide range of curing temperatures and control-able degree of cross linking [1]. however, it is reported that the epoxy resin without mineral filler cannot meet the requirement for its thermo-mechanical properties. khwarizmi engineering journal,vol. 11, no. 3, p.p. 96-101 (2015) tensile and compressive properties of kaolin rienforced epoxy jabbar hussein mohmmed department of material engineering/ university of technology jabbaraljanaby@yahoo.comemail: (received 2 september 2014; accepted 23 march 2015) with the addition of organic or inorganic compounds is of great interest nowadays, considering their large scale of applications. in the present work, composites of epoxy are synthesized with kaolin particles having different particle sizes as reinforcement. composites of epoxy with varying concentration ( prepared by using hand lay method. the variation of mechanical properties such as modulus of sile, and compressive strength with filler content was evaluated. the comp modulus of elasticity and compressive properties on addition of filler. in contrast, the tensile and yield strength of the in content. it is also observed that mechanical properties increase composite materials, epoxy risen, and kaolin. filled polymer composites have become attractive because of their wide applications and low cost. incorporating inorganic mineral fillers into plastic resin improves various physical properties of the materials such as mechanical strength, modulus . in general the mechanical properties of particulate filled polymer composites depend strongly on size, shape and distribution of filler particles in the matrix polymer and good adhesion at the interface oxy resin is widely used as a substrate material in electronic packaging industry. as one of the most widely used thermosetting resin, epoxy resin possess special chemical characteristics such as little or no by-products or low shrinkage, can be cured over a wide range of curing able degree of crosslinking [1]. however, it is reported that the epoxy resin without mineral filler cannot meet the mechanical properties. hence, many investigators have used various toughening filler with epoxy, such as alumina [1], silica powder and aramid fiber [2, 3], granite [4], and glass-fiber [5] in order to improve specific properties or reduce cost. in this investigation kaolin of variable particle size was added to epoxy. influences of the addition of these fillers on the mechanical properties (young's modulus, yield, tensile, and compressive strength) were examined. 2. experimental procedure 2.1. materials system the matrix material used for the present study was epoxy (type:cy233 supplied by ciba co.-german) having density in range of (1.1 g/cm3) at 25̊c and hardener (hy956). the properties and chemical structure of epoxy are presented in fig.1 and table 1. kaolin clay has a density of 2.64 g/cm³ with a general chemical formulation supplied by iraqi national company for al-khwarizmi engineering journal (2015) tensile and compressive properties of kaolin rienforced epoxy with the addition of organic or inorganic compounds is of great interest nowadays, oxy are synthesized with kaolin y with varying concentration (0 to 40 . the variation of mechanical properties such as modulus of sile, and compressive strength with filler content was evaluated. the composite showed improved in contrast, the tensile and yield strength of the mechanical properties increase with decrease in many investigators have used various toughening filler with epoxy, such as alumina [1], silica powder and aramid fiber [2, 3], granite [4], 5] in order to improve specific properties or reduce cost. in this investigation e particle size was added to epoxy. influences of the addition of these fillers on the mechanical properties (young's modulus, yield, tensile, and compressive strength) were rocedure used for the present study was epoxy (type:cy233 supplied by ciba-geigy. german) having density in range of (1.1-1.2 ˚c and hardener (hy956). the hemical structure of uncured in fig.1 and table 1. kaolin clay has a density of 2.64 g/cm³ with a general chemical formulation al 2si2o5(oh)4 iraqi national company for jabbar hussein mohmmed al geological survey and refinery was used in this study. this clay was milled by using a ball mill instrument, and it was sieved by using a sieve analyzer to obtain different particle size for kaolin (d<8, 18<d<25, 33<d<45, and 50<d<62 chemical composition and general properties of kaolin are presented in tables (2, and 3 fig. 1. chemical structure of uncured epoxy table 1, properties of epoxy. table 2, chemical composition of kaolin. table 3, general properties of kaolin. 2.2. mold preparation a standard steel sample for each type of tests was manufactured for the purpose of making the final mold. the molds were manufactured from the white cement material. manufacturing mold process can be summarized in the following steps: 1. forming a rectangular frame of wood for each mold and then put them on glass bases. quantity properties 1.1 density, g/cm3 1.5 modulus of elasticity, gpa 40.5 tensile strength, mpa 66.22 yield strength, mpa 82.3compressive strength, mpa sio2% al2o3% fe2o3% 52.48 31.31 2.094 mgo% na2o% cao% 0.33 0.28 0.462 quantity properties 2.64 density, g/cm3 white powder color 1755 melting point °c higher 225 fracture resistance endothermic at 260 thermal properties exothermic at 980 al-khwarizmi engineering journal, vol. 11, no. 97 geological survey and refinery was used in this study. this clay was milled by using a ball mill by using a sieve analyzer to obtain different particle size for kaolin 50<d<62 µm). the chemical composition and general properties are presented in tables (2, and 3) al structure of uncured epoxy [12]. a standard steel sample for each type of tests was manufactured for the purpose of making the final mold. the molds were manufactured from manufacturing mold process can be summarized in the following steps: forming a rectangular frame of wood for each mold and then put them on glass bases. 2. poured the mixture of white cement into the wooden structures. 3. put the standard steel samples in own m and kept for one hour. 4. take out the standard samples from molds. the cement material will take the form of standard samples. 5. take out the molds from the wooden frames. 2.3. preparation of composites for epoxy-kaolin composite, containing varying sizes (d<8, 18<d<25, 33<d<45, and 50<d<62 µ (0, 10, 20, 30, 40 %wt) of kaolin in an epoxy matrix were prepared for each test lay method. prior the mixing, the kaolin powder was washed thoroughly with water then dr oven at 110˚c for 2 h to remove any moisture. then, the required amounts of kaolin and epoxy were mixed mechanically. after 10 min of stirring, hardener was added and gently mixed with the mixture in the ratio of 3:1 by weight epoxy resin. mixing was continued for another 15 min. the final mixture was poured into cement molds and was allowed to cu temperature for 24 h. after this the composite was taken out the molds and post cured at 100 hr. the composite was allowed to cool to room temperature in the oven itself. 2.4. measurement of tensile compressive strengths tensile tests were carried out according to astm d638 [6] on the instron tensile testing machine 3710-016. the specimen type i with overall length 168 mm and width 29 mm was used in this test. a cross head speed of 10 mm/min was used and the test was performed at 25 ± 3 compressive test was performed instron tensile testing machine. fraction, 4 specimens have diameter of 12.7 mm and height of 25.4 mm with different particle size in addition to specimen for net epoxy produced and tested according to [6]. quantity 1.1-1.2 1.5 40.5 66.22 82.3 tio 2% 1.43 l.o.i% 10.93 endothermic at 260°c exothermic at 980°c khwarizmi engineering journal, vol. 11, no. 3, p.p. 96101 (2015) poured the mixture of white cement into the put the standard steel samples in own mold take out the standard samples from molds. the cement material will take the form of take out the molds from the wooden frames. omposites kaolin composite, 17 samples containing varying sizes (d<8, 18<d<25, 50<d<62 µm) and weight percent (0, 10, 20, 30, 40 %wt) of kaolin in an epoxy for each test by using hand prior the mixing, the kaolin powder was with water then dried in an to remove any moisture. then, the required amounts of kaolin and epoxy were mixed mechanically. after 10 min of stirring, hardener was added and gently mixed with the mixture in the ratio of 3:1 by weight of epoxy resin. mixing was continued for another 15 min. the final mixture was poured into white molds and was allowed to cure at room . after this the composite was taken out the molds and post cured at 100˚c for 4 site was allowed to cool to room temperature in the oven itself. measurement of tensile and compressive strengths tensile tests were carried out according to [6] on the instron tensile testing the specimen type i with erall length 168 mm and width 29 mm was used a cross head speed of 10 mm/min was used and the test was performed at 25 ± 3oc. was performed also by using a instron tensile testing machine. for each weight have diameter of 12.7 mm with different particle size in addition to specimen for net epoxy were produced and tested according to astm d696 jabbar hussein mohmmed al-khwarizmi engineering journal, vol. 11, no. 3, p.p. 96101 (2015) 98 3. results and discussion 3.1. modulus of elasticity young’s modulus is the stiffness (the ratio between stress and strain) of a material at the elastic stage of a tensile test. figure 1 shows the effect of kaolin content (wt%) to the modulus of elasticity of the composites. as expected, the young’s modulus of the composite markedly improved with the addition of kaolin content. this improvement because of the kaolin particle is inherently stiff and thus influences the stiffness of the composite as a whole (bulk). a similar observation was made by h. salmah et.al [7] in the case of polypropylene/ kaolin composites. the rate of increase of young’s modulus was comparable to the increase in concentration of kaolin and the decrease in particle size. thus it was confirmed that the total area available to deformation stress played an important role. these results are in good agreement with results obtained by s. bose and p.a. mahanwar [8], and jawad kadhim et al [9] in the case of polymethyl methacrylate (pmma)/ silica composite. fig. 1. variation in young's modulus of different particle size kaolin with varying concentration. 3.2. tensile strength figure 2 shows the effect of filler loading on tensile strength of epoxy/ kaolin composite with different particle size. it can be seen that the tensile strength decreases with increasing filler loading. the decrease in tensile strength may be due to the non-uniform distribution of kaolin particles in the matrix. in addition to, brittleness of kaolin particles causes the concentration of local stresses at these particles and leads to the deterioration of tensile strength of the composite. these results are in agreement with those obtained by s. bose and p.a. mahanwar [10]. it was also observed that the rate of decrease of strength was higher when larger particle size was used. smaller particles have a higher total surface area for a given particle loading. this indicates that the strength increases with increasing surface area of the filled particles through a more efficient stress transfer mechanism. most investigators have enumerated that particle size is inversely related to reinforcing character and that an increase in surface area increases the composite mechanical properties [10, 11]. fig. 2. variation in tensile strength of different particle size kaolin with varying concentration 3.3. yield strength the effect of filler loading on the yield strength of kaolin filled epoxy composites with different particle size is shown in fig. 3. it is clearly shown that, the yield strength of all epoxy composites decreases with increasing filler loading. significant drop in the value of yield strength was observed at filler loading as in the range of (0-10) wt.%. in polymer matrix composites (pmc), most of the deformation occurs in the matrix phase. as the percentage of kaolin content increases, the ability of the matrix phase to deform plasticity is also reduced as shown in figure 3. this can be explained by plastic deformation mechanism. ability of the material to plasticity deformed is largely determined by the mobility of the molecular chain (molecular motion) to take place under applied load. the presence of rigid particles such as kaolin in this case has restricted the mobility of the molecular chain to pass each other and orientation which consequently resulted in instantaneous failure (brittle failure) as the yield stress is reached. therefore, rigidity of kaolin particles has directly responsible for the decreases in the yield strength value. however, at similar filler loading, kaolin filled epoxy composites with smaller particle size have higher yield strength 40.0030.0020.0010.00.00 filler loading (wt%) 6.00 5.00 4.00 3.00 2.00 1.00 e v al u e (g p a) 50<d<62 33<d<45 18<d<25 d<8 40.0030.0020.0010.00.00 filler loading (wt%) 40.00 35.00 30.00 25.00 20.00 te ns ile s tr en g th ( m p a) 50<d<62 33<d<45 18<d<25 d<8 jabbar hussein mohmmed al-khwarizmi engineering journal, vol. 11, no. 3, p.p. 96101 (2015) 99 than similar composites with larger particle size. this may be attributed to an increase in the kaolin particle strength with a decrease in particle size, because the probability of a strength-limiting flaw existing in the volume of the material decreases. at relatively large particle sizes of this material, a significant amount of particle cracking takes place during extrusion prior to testing. cracked particles do not carry any load effectively and can be effectively thought of as voids, so the strength is lower than that of the unreinforced material. the same trend was found by shao-yun fu et al. [12] and samir nassaf mustafa [13]. fig. 3. variation in yield strength of different particle size kaolin with varying concentration. 3.4. compressive strength the variation of compressive strength for the composites under study with filler content is presented in fig. 4. in this figure it was observed that the compressive strength increased drastically on addition of filler in both the larger and smaller particle sizes of kaolin but the rate of change of compressive strength with varying percentage of filler was higher in the case of smaller particle size as compared to larger particle size of kaolin. the smaller kaolin particles are expected to improve the stress transfer between the matrix and the filler by the formation of a strong filler/matrix interface. a similar observation was made by singla and chawla [14] and ibtihal et.al. [15] in the case of fly ash/ epoxy composites and silica/ epoxy composites respectively. the trend of the variation of compressive properties with filler is similar to that of the variation of young's modulus properties. further, the enhanced compressive strength properties of the composites over that of the matrix may be due to the stiff nature of the filler. fig. 4. variation in compressive strength of different particle size kaolin with varying concentration. table 4, all experimental results for each testing. no. kaolin added (%) particle size (µm) modulus of elasticity (gpa) yield strength (mpa) tensile strength (mpa) compressive strength (mpa) 1 .00 .00 1.5 40.5 66.22 82.3 2 10.00 d≤8.00 2.93 40.3 49.21 88.67 3 20.00 d≤8.00 3.46 . 34.25 47.56 105.22 4 30.00 d≤8.00 4.28 31.56 42.43 111.15 5 40.00 d≤8.00 5.66 27.42 36.7 123.3 6 10.00 18≤d≤25 2.77 38.5 47.52 84.36 7 20.00 18≤d≤25 3.08 33.59 45.1 102.4 8 30.00 18≤d≤25 4.11 27.22 39.8 106.3 9 40.00 18≤d≤25 5.31 25.52 33.4 117.22 10 10.00 33≤d≤45 2.53 35.22 42.11 82.27 11 20.00 33≤d≤45 2.99 30.59 39.3 91.23 12 30.00 33≤d≤45 3.82 26.4 34.15 98.9 13 40.00 33≤d≤45 4.76 23.9 29.62 108.59 14 10.00 50≤d≤62 1.58 30.15 41.5 78.86 15 20.00 50≤d≤62 2.87 28.15 39.99 84.04 16 30.00 50≤d≤62 3.95 23.44 34.22 93.18 17 40.00 50≤d≤62 4.43 19.22 27.5 99.11 40.0030.0020.0010.00.00 fller loading (wt%) 70.00 60.00 50.00 40.00 30.00 y ie ld s tr e n g th ( m p a ) 50<d<62 33<d<45 18<d<25 d<8 40.0030.0020.0010.00.00 filler loading (wt%) 140.00 120.00 100.00 80.00 60.00 c om pr es si ve s tr en gt h (m p a) 50<d<62 33<d<45 18<d<25 d<8 jabbar hussein mohmmed al-khwarizmi engineering journal, vol. 11, no. 3, p.p. 96101 (2015) 100 4. reference [1] erfansuryani abdul rashid, hazizan mdakil, kamarshahariffin, chee choong kool, "the flexural and morphological properties of α-alumina filled epoxy composites", malaysian polymer journal (mpj), vol 1, no. 1, 2006. [2] haiying wang a, yilong bai, sheng liu, jiali wu, c.p. wong, "combined effects of silica filler and its interface in epoxy resin", actamaterialia, vol.50, 2002. [3] sun, y., zhang, z., wong, c.p., "influence of interphase and moisture on the dielectric spectroscopy of epoxy/silica composites, polymer journal, vol.46, 2005. [4] ramakrishna h. v. and rai s. k, "utilization of granite powder as a filler for polybutylene terepthalate toughened epoxy resin", journal of minerals & materials characterization & engineering, vol. 5, no.1, 2006 [5] alvarez, v.a., valdez, m.e., vasquez, a., "dynamic mechanical properties and interphase fiber/matrix evaluation of unidirectional glass fiber/epoxy composites", polymer testing, vol.22, 2003. [6] annual book of astm, section 8, vol.08.01 plastic, "am.soc. test mat." philadelphia, (2004). [7] h. salmah, c.m. ruzaidi and a.g. supri, "compatibilisation of polypropylene/ ethylene propylene dieneterpolymer/ kaolin composites: the effect of maleic anhydride-grafted-polypropylene", journal of physical science, vol. 20, no.1, 2009. [8] suryasarathi bose, and p.a. mahanwar, " effect of particle size of filler on properties of nylon-6", journal of minerals & materials characterization & engineering, vol. 3, no.1, 2004. [9] jawad kadhim oleiwi, farhad m. othman, israa faisal qhaze, " a study of mechanical properties of poly methacrylate polymer reinforced by silica particles (sio2)", eng. & tech. journal, vol. 31, no. 15, 2013. [10] suryasarathi bose and p.a.mahanwar, " effect of fly ash on the mechanical, thermal, dielectric, rheological and morphological properties of filled nylon6", journal of minerals & materials characterization & engineering, vol. 3, no.2, 2004. [11] najat j. saleh & samir nassaf mustafa, " a study of some mechanical, thermal and physical properties of polymer blend with iraqi kaolin filler", eng. & tech. journal, vol. 29, no. 11, 2011. [12] shao-yun fu, xi-qiao feng, bernd lauke, and yiu-wing mai, " effects of particle size, particle/matrix interface adhesion and particle loading on mechanical properties of particulate–polymer composites", science direct, composite journal, part b, no. 39, 2008 [13] samir nassaf mustafa, " effect of kaolin on the mechanical properties of polypropylene/ polyethylene composite material", diyala journal of engineering science, vol. 5, no. 2, 2012. [14] manoj singla, and vikas chawla, " mechanical properties of epoxy resin – fly ash composite ", journal of minerals & materials characterization & engineering, vol. 9, no.3, 2010. [15] ibtihal-al-namie, ahmed aladdin ibrahim, manal fleyah hassan, " study the mechanical properties of epoxy resin reinforced with silica (quartz) and alumina particles", the iraqi journal for mechanical and material engineering, vol.11, no.3, 2011. ر ���ن ���د � � � )2015( 96101، ���� 3، ا���د����11 ا����ا� �ارز � ا����� 101 �ؤو������ .�اص ا�,� وا+*()�ط �&%$�#"� ا���! � $0�ر /"�� ��� ��� ھ���� ا���اد/ ��� ا�$#"!� ا� ����� jabbaraljanaby@yahoo.com �%&'ا,+ &و() ا�: ��1 ا� �&ة -) ا���8 ا�7#6& (5&ا ���4ى ا��ا�2 "1 ا� 0'�/#ت -) '+ ��ا�!�b @/�%� را@�$#ت ا,%'�+�) ?<6#-� "&+'#ت =>�%� أو , =>�%� ھ) ذات أھ� �c4 d" ��'�'e م#$eg? 1��'#ت ا��#ؤو�'e 2" (�+�'%,ا+'#ت "1 ا& " b�= �@ ،(�#7ا� #jck�?�%�/@ ا+'#ت . "#دة& " &�<7@ �@ �c4 d" l�ا,%'�+�) ? &ا+ �� "b"#!" bt ا��&و(�، "/#و"� ا�d>�ع، ا��r، . "1 ا��#ؤو���d �#? 1ام ط&%/� ا�/��'� ا���و%�) "1 ا��زن% ٤٠-٠(��)#���& -) ا��dاص ا��v درا�� ا� �@ �#(] آx&، ا(cd>8 "/#و"� . "#دة ا� /�%�اظj&ت ا�� &ا+'#ت @1�7 -) "!#"b ا��&و(� و�xاص ا,(>v#ط "2 إ6#-� . وا,(>v#ط "2 "7 �ى ا� /�%� 1" 1��2 ا�7#,ت. ا��r وا�d>�ع ��4 &ا+'#ت "2 ز%#دة "7 �ى ا��#ؤو���2 @/4�e b$� ا�7'�'#ت -) " ����)#�� .+^�[، ��e\ @1�7 ا��dاص ا�� al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 1219 (2015) corrosion behavior of v2alc and cr2alc compared with ss 316l in naoh at four temperatures rana a. anaee* ahmed m. al-ghaban** russul f. faleh*** *,**,***department of materials engineering/ university of technology *email: dr.rana_afif@yahoo.com **email: ahmed_gaban@yahoo.com ***email: russulfadhelfaleh@gmail.com (received 21 may 2014 ; accepted 18 january 2015) abstract this work involves the manufacturing of max phase materials include v2alc and cr2alc using powder metallurgy as a new class of materials which characterized by regular crystals in lattice. corrosion behavior of these materials was investigated by potentiostat to estimate corrosion resistance and compared with the most resistant material represented by ss 316l. the experiments were carried out in 0.01n of naoh solution at four temperatures in the range of 30–60 o c. polarization resistance values which calculated by stern-geary equation indicated that the max phase materials more resistant than ss 316l. also cyclic polarization tests confirmed the resistivity of max phase materials through disappears of hysteresis loop. key word: max phase materials, corrosion behavior, v2alc, cr2alc. 1. introduction materials technology is a very vital part of modern technology. technological development is often limited by the properties of materials and knowledge about them. some properties, such as that determining corrosion behavior, are most difficult to map and to control [1]. in general, the development of modern society and industry has led to a stronger demand for engineers with specialized knowledge in corrosion. there are a number of reasons for this; the application of new materials requires new corrosion knowledge, industrial production has led to pollution, acidification and increased corrosivity of water and the atmosphere, stronger materials, thinner cross-sections and more accurate calculation of dimensions make it relatively more expensive to add a corrosion allowance to the thickness, the widespread use of welding has increased the number of corrosion problems, and other factors [2] many authors were interested fabrication of max phase materials and studied of some their physical and mechanical properties. zhou et al. in 2001 determined the electronic and structural properties of the layered ternary compound ti3alc2 using the ab initio pseudopotential method based on density functional theory [3]. wang and zhou in 2002 investigated the isothermal oxidation behavior of ti2alc at intermediate temperatures of 500, 600, 700, 800, and 900°c in flowing air by means of thermogravimetric analysis, x-ray diffraction (xrd), raman spectroscopy, and scanning electron microscopy (sem)/energy dispersive spectroscopy [4], also they fabricated the microstructure of polycrystalline ti3alc2 by the solid–liquid reaction mailto:dr.rana_afif@yahoo.com rana a. anaee al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 1219 (2015) 13 synthesis and simultaneous in situ hot pressing process was investigated by sem and tem [5]. zhimei et al. [6] performed theoretical studies of the bulk modulus of m2alc, where m5ti, v, cr by means of ab initio total energy calculations using the projector augmented wave methods. the bulk modulus of m2alc increases as ti is substituted with v and cr by 19% and 36%, respectively. this can be understood since the substitution of ti by v and cr is associated with an extensive increase in the m–al and m–c bond energy. jochen et al. [7] calculated the equilibrium volume and the density of states (dos) of cr2alc for antiferromagnetic (afm), ferromagnetic (fm) and paramagnetic (pm) configurations by ab initio total energy calculations. based on a comparison of the cohesive energies as well as the dos for all three magnetic configurations we have identified the fm configuration to be metastable. furthermore, they report the structural characterization of polycrystalline cr2alc thin films grown by magnetron sputtering. the charge density distribution suggests that the chemical bonding between cr and c in cr2alc is very similar to the one in cubic crc. hettinger et al. [8] investigated the electronic, magnetotransport, thermoelectric, thermal, and elastic properties of four m2alc phases: ti2alc, v2alc, cr2alc and nb2alc. the electrical conductivity, hall coefficient, and magnetoresistances are analyzed within a two-band framework assuming a temperature-independent charge carrier concentration. with room temperature thermal conductivities in the 25 w/m k range 45 w/m k for v2alc, they are also good thermal conductors. yuri et al. [9] synthesized a near-single-phase ti3alc2 ternary carbide from 3ti–1.1al–1.8c powder blend, both by the wave propagation and thermal explosion (te) modes of self-propagating high temperature synthesis. zhimei et al. [10] studied m2aln phases, where m = ti, v, and cr, by means of ab initio total energy calculations. the bulk modulus of m2aln is generally higher than that of the corresponding m2alc phase, which may be explained by an extra electron in the former phases contributing to stronger chemical bonding. wubian et al. [11] fabricated cr2alc ceramics by hot-pressing using cr, al and c powders as starting materials. the phase assemblages of the samples consisted of cr2alc, as a major crystalline phase, together with a very small amount of cr7c3 and an unknown phase. its thermal and electrical as well as mechanical properties were determined. wu-bian et al. [12] fabricated dense and predominantly single-phase samples of cr2alc, together with a trace amount of cr7c3 by hot pressing of a mixture of chromium, aluminum, and graphite powders at 14001c for 1 h. the hardness, young’s modulus, flexural strength, and compressive strength of cr2alc samples were 5.2, 288 gpa, 483729, and 1159723 mpa, respectively, which are comparable with those of ti3alc2 and nb2alc. the material exhibits good damage tolerance. denis et al. [13] studied the electronic structure of tan+1alcn (space group p63/mmc, n = 1–3) under uniform compression from 0 to 60 gpa and at temperatures from 0 to 1500 k using ab initio calculations. yanchun et al. [14] synthesized new layered compounds, (v0.5cr0.5)3alc2, (v0.5cr0.5)4alc3, and (v0.5cr0.5)5al2c3 by reactive hot pressing v, cr, al, and graphite powders. the crystal structures of these new phases were determined using a combination of x-ray diffraction and scanning transmission electron microscopy. wubian et al. [15] studied the isothermal oxidation behavior of cr2alc ceramics oxidized in air at 1100 and 1250 o c for 20 h. wubian et al. [16] studied the compressive properties of ternary compound cr2alc at different temperatures and strain rates. zhou et al. [17] synthesized dense bulk cr2alc by hot-pressing of cr, cr3c2 and al powders as starting materials. the results showed that cr2alc grains have columnar and plate-like shapes, and that it is a good electrical and thermal conductor. chang et al. [18] studied the cr2alc ternary carbide in chemical and oxidation resistances as well as mechanical properties at high temperatures. the aim of present work is fabricate the v2alc and cr2alc materials by powder metallurgy and study their corrosion behavior in basic medium of 0.01n naoh solution and comparison their behavior with ss 316l which act as most metallic resistant alloy at four temperatures 30, 40, 50 and 60 o c. rana a. anaee al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 1219 (2015) 14 2. experimental procedure to fabricate the v2alc and cr2alc samples v, cr, c, and al powders (99% pure) were mixed in stoichiometric proportions, ball milled (baird & tatlock) for 20 min at high level of speed for each sample, cold pressed using the hydraulic press machine type (mega 50 ton max) and placed in a graphite die in a vacuum hot press (mti corporation gls 1500x). the latter was evacuated and heated to 1100-1350 °c for 6 h. the sample was held at the maximum applied uniaxial pressure ~3 ton for 10 min. to characterize the prepared max phase material, x-ray diffraction (xrd) analysis was used in order to find out the composition and phase identification of each sample using shimadzu x-ray diffractometer (type xrd6000/7000). potentiostatic and cyclic polarization measurements were carried out with winking mlab 200 potentiostat from bank-elektronik with electrochemical standard cell and sci electrochemical software at a scan rate 5 mv.sec -1 . polarization experiments were started when the rate at which open circuit potential (eoc) changed was less and more 300mv[19]. saturated calomel electrode (sce) was used as reference electrode and pt as counter electrode, while working electrodes were v2alc, cr2alc and ss 316l. the three electrodes arranged as shown in fig. 1. the specimens were polished, degreased with acetone and rinsed with distilled water and then they put in holder to insulate all but one side with exposed surface area (1 cm 2 ). the main results obtained were expressed in terms of the corrosion potentials (ecorr) and corrosion current density (icorr) in addition to measure the tafel slops by tafel extrapolation method [20]. from the values of tafel slopes and corrosion current density, the polarization resistances values can be calculate according to stern-geary equation as follow: 𝑅𝑝 = 𝑑𝐸 𝑑𝑖 𝑖=0 = 𝑏𝑎 ∗ 𝑏𝑐 2.303∗ 𝑖𝑐𝑜𝑟𝑟 ∗ 𝑏𝑎+𝑏𝑐 … (1) where bc and ba are cathodic and anodic tafel slop respectively. electrolyte solution was 0.01n naoh at (ph=12) which used for corrosion tests. all experiments were achieved at four temperatures include 30, 40, 50 and 60 o c which adjusted by water bath in jacket cell as shown in fig. 1-b. (a) (b) fig. 1. set up of corrosion test, (a) electrical circuit, (b) standard cell. 3. results and discussion the x-ray powder diffraction patterns collected at 1 atm for v2alc and cr2alc are shown in fig.(2). for two materials, all major peaks were assigned to the hexagonal structure with the space group p63 /mmc. a few low intensity impurity peaks were not identified. the variation of potentials with time for max phase materials and ss 316l (for comparison only) in basic medium of sodium hydroxide are shown in figure (3) for 600 sec. at scan rate 5 mv.sec -1 , these figures indicate that there are protective film may be formed on material surfaces in basic medium for prepared max phase materials. generally, the potentials of v2alc more noble than these for cr2alc and ss 316l at constant temperature due to breakdown and repairing of cr2o3 in the last two materials. in the other word, polarization rana a. anaee al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 1219 (2015) 15 characteristics recoded in 0.01n naoh show that v2alc undergoes active dissolution at potentials more positive than other materials, ex., ecorr of v2alc was -473.5 mv at 60 o c, while for cr2alc and ss 316l were -1191.8 and -1200.7 mv respectively at the same temperature (see table 1). fig. 2. xrd for prepared max material. figure (4) shows the polarization test of three materials in 0.01n naoh solution at four temperatures, indicating the cathodic and anodic regions. the variation of potentials with current densities for v2alc and cr2alc curves more than for ss 316l due to stable protective film in max phase materials compared with ss 316l in addition to the high resistance needed to rupture the regular crystals in structure. corrosion parameters were calculated by tafel extrapolation method are found in table (1) and the order of corrosion current densities take the following sequence: icorr in 0.01n naoh v2alc < cr2alc < ss 316l fig. 3. potential–time measurements of materials in 0.01n naoh at four temperatures. rana a. anaee al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 1219 (2015) 16 table 1, corrosion parameters for v2alc, cr2alc and ss316l in 0.01n naoh at four temperatures. material temp. oc -eoc mv -ecorr mv icorr μa.cm-2 -bc mv.dec-1 +ba mv.dec-1 rp x103 ω.cm2 v2alc 30 289 394.7 5.23 147.8 151.4 6.209 40 340 431.0 5.50 86.4 183.2 4.635 50 337 497.1 10.32 93.9 98.9 2.029 60 377 473.5 11.45 130.5 364.8 3.645 cr2alc 30 1209 1166.5 16.60 150.9 241.1 2.428 40 931 975.3 18.47 267.6 266.5 3.139 50 1123 1133.6 19.29 152.8 317.8 2.323 60 1144 1191.8 31.26 106.2 164.1 0.896 ss 316l 30 1184 1183.5 37.81 91.0 134.7 0.624 40 1191 1181.6 86.24 136.8 201.2 0.410 50 1199 1187.8 99.89 154.5 234.2 0.405 60 1207 1200.7 221.08 170.6 271.6 0.206 fig. 4. tafel plot of materials in 0.01n naoh at four temperatures. the term (rp) corresponds to the resistance (r) of the metal/solution interface to charge–transfer reaction. it is also a measure of the resistance of the metal to corrosion in the solution in which the metal is immersed. the values of rp are presented in table (1). these data indicate that the polarization resistance was good agreement with the results of corrosion current density, where can be seen that the polarization resistance values were for v2alc followed by cr2alc and then for ss 316l. the polarization resistance of max phase materials varied with increasing temperature due to variation of cathodic and anodic sites on the material surface, but at constant temperature the resistance of these materials more than for ss 316l, for example at 60 o c, the polarization resistance of v2alc was 3.645 ω.cm 2 , while for cr2alc and ss 316l were 0.896 and 0.206 ω.cm 2 respectively. generally, the sequence of rp take the order: rp ω.cm 2 v2alc > cr2alc > ss 316l the corrosion current density (icorr) is a kinetic parameter and represents the rate of corrosion under specified equilibrium condition. any factor that enhances the value of (icorr) results in an enhanced value of the corrosion rate on pure kinetic ground. according to the results of corrosion current density, can be say that the highest corrosion rate was for ss 316l followed by cr2alc. while v2alc has lowest corrosion rate. the cyclic polarization of max phase materials shows no chance to pitting compared with ss 316l, which is recognized as a dangerous form of rana a. anaee al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 1219 (2015) 17 corrosion, in tested media as shown in figure (5). this means that v2alc and cr2alc materials were exhibited a good resistance to corrosion in 0.01n naoh solution at different temperatures in the range of 30 – 60 o c. fig. 5. cyclic polarization of materials in 0.01n naoh at four temperatures. 4. conclusion from the study of corrosion behavior for max phase materials can be concluded that these materials have good corrosion resistance in basic medium. this conclusion was confirmed through the potential – time measurements, polarization test and cyclic polarization due to homogenously structures and regular crystal in lattice of these ceramic materials. the corrosion parameters indicated that the eoc and ecorr values were more negative for ss 316l followed by cr2alc and then v2alc. the corrosion current density (or corrosion rate) take the order ss 316l > cr2alc > v2alc. polarization resistance values which calculated depending on tafel slopes and current density indicated that the most resistance was for v2alc due to protective layer on its surface which is more stable than that formed on cr2alc and ss 316l surfaces. 5. references [1] payer jh, boyd wk, dippold dg, fisher wh. materials performance, nace, may 1980. [2] hoar tp (chairm.). report of the committee on corrosion and protection, london: dept. of trade and industry, h.m. stationary office, 1971. [3] zhou y. c., wang x. h., sun z. m. and chen s. q. 2001, “electronic and structural properties of the layered ternary carbide ti3alc2”, j. mater. chem., 11, 2335–2339. [4] wang x.h. and zhou y.c. 2002, “intermediate-temperature oxidation behavior of ti2alc in air”, j. mater. res., vol. 17, no. 11. [5] wang x.h., zhou y.c. 2002, “microstructure and properties of ti3alc2 prepared by the solid–liquid reaction synthesis and simultaneous in-situ hot pressing process”, acta materialia, 50, 3141–3149 [6] zhimei sun, rajeev ahuja and sa li, and jochen m. schneider 2003, “structure and bulk modulus of m2alc .mäti, v, and cr”, appl. phys. lett., vol. 83, no. 5. [7] jochen m. schneidera,, zhimei suna, raphael mertensa, fatih uestela, and rajeev ahujac 2004, “ab initio calculations and experimental determination of the structure of cr2alc”, solid state communications 130, 445–449. [8] hettinger j. d., lofland s. e., finke p., meehan t., palma j., harrell k., gupta s., ganguly a., el-raghy t. and barsoum m. w. 2005, “electrical transport, thermal transport, rana a. anaee al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 1219 (2015) 18 and elastic properties of m2alc (m=ti, cr, nb, and v)”, physical review b 72, 115-120. [9] yuri khoptiar, irena gotman,w and elazar y. gutmanas 2005, “pressure-assisted combustion synthesis of dense layered ti3alc2 and its mechanical properties”, j.am.ceram.soc.,88,28-33. [10] zhimei sun, denismusic, rajeev ahuja and jochen m schneider 2005, “ab initio study of m2aln (m = ti,v, cr)”, j. phys.: condens. matter, 17, l15–l19. [11] wubian tian, peiling wang, guojun zhang, yanmei kan, yongxiang li, and dongsheng yan 2006, “synthesis and thermal and electrical properties of bulk cr2alc”, scripta materialia, 54, 841-846. [12] wu-bian tian, pei-ling wang, guo-jun zhang, yan-mei kan, and yong-xiang li 2007, “mechanical properties of cr2alc ceramics”, j. am. ceram. soc., 90 [5] 1663– 1666. [13] denis music, jens emmerlich and jochen m schneider 2007 “phase stability and elastic properties of tan+1alcn(n = 1–3) at high pressure and elevated temperature”, j. phys.: condens. matter, 19, 136207 (9pp) [14] yanchun zhou, fanling meng, and jie zhang 2008, “new max-phase compounds in the v-cr-al-c system”, j.am.ceram.soc., 91(4) 1357–1360. [15] wubian tian, peiling wang, yanmei kan, and guojun zhang 2008, “oxidation behavior of cr2alc ceramics at 1100 and 1250oc”, j mater sci., 43:2785–2791. [16] wubian tian, zhengming sun, and hitoshi hashimoto 2009, “compressive deformation behavior of ternary compound cr2alc”, j mater sci, 44:102–107. [17] zhou w.b, mei b.c. and zhu j.q. 2009, “on the synthesis and properties of bulk ternary cr2alc ceramics”,materials sciencepoland,vol.27,no.4/1. [18] chang-sam kim, sung ik hwang, jung-soo ha, seung-min kang and deock-soo cheong 2010, “synthesis of a cr2alc-ti2alc ternary carbide”, journal of ceramic processing research. vol. 11, no. 1, pp. 82-85. [19] asm handbook volume 13, 1992. corrosion. materials park, ohio, usa: asm international. for an easier read: jones lw: corrosion and water technology for petroleum producers. tulsa, oklahoma. [20] robert g., john r. and david w. 2003, “electrochemical techniques in corrosion science and engineering”, by marcel dekker, inc. (2015) 1219، صفحة 2، العذد11دالهنذسية المجل الخىارزميجلة م رنا عفيف عنائي 19 هيذروكسيذ في بالمقارنة مع الفىالر المقاوم للصذأ cr2alcو v2alcكلي للمىاد آالسلىك الث عنذ اربع درجات حرارية الصىديىم ***رسل فاضل فالح **الغباناحمذ محمذ * عنائيرنا عفيف اىجبٍعت اىخنْىىىجيت / قسٌ هْذست اىَىاد ***،**،* dr.rana_afif@yahoo.com : االىنخشوّي اىبشيذ * ahmed_gaban@yahoo.com : االىنخشوّي اىبشيذ ** russulfadhelfaleh@gmail.com : االىنخشوّي اىبشيذ *** الخالصة عذ ٍِ اىَىاد اىجذيذة اىََيزة ببّخظبً في اىشبنت اىبيىسيت ببسخخذاً ٍيخبىىسجيب اىَسبحيق، وحٌ دساست اىخي ثُت maxيخضَِ هزا اىبحث حصْيع ٍىاد اىطىس اجشيْج . 316lببىفىالر اىَقبوً ىيصذأ ميي ىهزٓ اىَىاد ببسخخذاً اىَجهبد اىسبمِ ىخقذيش ٍخغيشاث اىخأمو واىَقبسّت ٍع اىَبدة االمثش ٍقبوٍت واىََثيت آاىسيىك اىج وقذ بيْْج . دسجت ٍئىيت 60 –30ّىسٍبىيت وعْذ اسبع دسجبث حشاسيت ضَِ اىَذي 0.01جَيع اىخجبسة في وسط قبعذي ٍِ هيذسومسيذ اىصىديىً بخشميز مَب اُ االسخقطبة اىحيقي امذ . ٍِ اىفىالر اىَقبوً ىيصذأجيشي ببُ اىَىاد اىَحضشة حَخيل ٍقبوٍت افضو -ّخبئج ٍقبوٍت االسخقطبة اىَحسىبت بَعبوىت سخيشُ .ٍقبوٍيت هزٓ اىَىاد ٍقبسّت ٍع اىفىالر اىَقبوً ىيصذأ ٍِ خاله عذً ظهىس اىحيقت اىهسخيشيت mailto:dr.rana_afif@yahoo.comالبريد mailto:dr.rana_afif@yahoo.comالبريد mailto:dr.rana_afif@yahoo.comالبريد mailto:dr.rana_afif@yahoo.comالبريد mailto:dr.rana_afif@yahoo.comالبريد mailto:dr.rana_afif@yahoo.comالبريد (microsoft word \323\332\317 \344\314\355\31030-40) al-khwarizmi engineering journal al-khwarizmi engineering journal,vol. 13, no. 4, p.p. 3040 (2017) natural-convection phenomenon from a finned heated vertical tube: experimental analysis saad najeeb shehab department of mechanical engineering / engineering faculty / al-mustansiriayah university email: saad_najeeb16@ yahoo.com (received 29 march 2017; accepted 21 may 2017) https://doi.org/10.22153/kej.2017.05.004 abstract in this work, an experimental analysis is made to predict the thermal performance of the natural-convection phenomenon from a heated vertical externally finned-tube to surrounding air through an open-ended enclosure. two different configurations of longitudinal rectangular fin namely, continuous and interrupted are utilized with constant thickness, different numbers, and different heights are extended radially on the outer surface of a heated tube. the tube is heated electrically from inner surface with five varied power input magnitudes. the effect of fins configuration, fins number, fins height, and heat flux of the inner tube surface on the thermal performance of natural convection have been studied and analyzed experimentally. obtained results show that the tube with twelve interrupted longitudinal fins gives the best natural-convection thermal performance in terms of average nusselt number, about 20% greater than that for the tube with continuous fins. experimental correlations to predict the average nusselt number for the heated tubes with continuous and interrupted longitudinal fins are proposed. the present data are compared to previous study and good convergence is noticed. keywords: vertical tube, continuous, interrupted, finned, natural-convection. 1. introduction the natural-convection heat transfer from a vertical, horizontal, and inclined heated finned tube in different fin positions to surrounding air occurs in a many industrial and engineering applications. the importance applications are heat exchangers, evaporators, condensers, oil cooling systems, solar collectors, systems of energy storage,…and etc. the main purpose of these systems or equipments is to increase of heat dissipation rate from tube surface by utilizing different configuration of fins with varying heights and numbers, and high thermal conductivity materials. morgan [1] published a review of articles for the natural heat convection from outside surface of a heated smooth circular cylinder to surrounding air. he correlated the available experimental data to predict the nusselt number values based on the diameter of cylinder for a wide range of rayleigh numbers. stewart and verhulst [2] experimentally investigated the two dimensional natural-convection from a two heated copper horizontal tubes to cooled rectangular-section enclosure at constant temperature condition to simulate the naturalconvection heat transfer in systems of the underground thermal distribution. they correlated the experimental data to determine the nusselt number for rayleigh numbers ranging from 2.1×108 to 4.8×109, and found that the naturalconvection heat coefficients computed for underground or utility corridors case with air as working fluid smaller compared with other experimental correlations for concentric tubes. wu and tao [3] numerically simulated the heat transfer by laminar natural-convection from a heated horizontal compound cylinder with longitudinal external fins. they utilized the saad najeeb shehab al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 3040 (2017) 31 conjugated computational approach with primitive variables, and found the optimum fins number at a fixed fin height and the optimum fin height for a constant fins number. kadhim and abdulhussain [4] performed an experimental investigation for natural-convection from external surface of finned cylinder to surrounding air. they used two configuration of an external fins namely, triangular and rectangular with different inclination angles of cylinder and heat fluxes, and noted that the heat transfer from the triangular finned-cylinder is maximum at an inclination 90o (vertical position). dogan et al. [5] presented a numerical investigation for natural-convection heat transfer from annular fins on a heated horizontal cylinder. they studied the effect of fin spacing, fin diameter, and temperatures difference between the base and the surrounding on the performance of heat transfer. they suggested a correlation to obtain the optimum fin spacing as function of fin diameter and rayleigh number. totala et al. [6] presented an experimental investigation for natural heat convection from a heated vertical cylinder to surrounding air. they evaluated experimentally the local natural convection heat transfer coefficient along the height of cylinder and compared the results of them with obtained results from a theoretical part and they found a good convergence between of them. also, they found the maximum values of local heat transfer coefficient at the beginning and gradually reduces in the upward direction. niezgoda-zelasko and zelasko [7] experimentally investigated the natural and forced-convection from longitudinally finned cylinder in vertical position. they used two air flow velocities, parallel and cross flow to the cylinder axis and computed experimentally convection heat transfer coefficients values for all cases. they found that the convection heat transfer coefficients for case of perpendicular flow 22% greater than case of parallel flow for cylinder axis and developed experimental correlations to compute heat transfer coefficient for natural and two cases of forcedconvection. lee et al. [8] experimentally investigated the natural heat convection from vertical cylinder with two different types of platefins namely, radial and inclined. they studied many parameters like number of fins, inclined angle of fins, and base temperatures on the convection heat transfer rate. they observed that the optimal heat resistance of cylinder with inclined plate-fins is 30% less with that of cylinder with radial plate-fins. the objective of the present work is to present an experimental analysis for the natural heat convection from vertical externally finned-tube to surrounding air inside an open-ended enclosure utilizing two different configurations of external longitudinal fin, continuous and interrupted, with different numbers, heights, and regular distributed radially on the external surface of the heated tube. the influence of fins shape, fins number, fin height, and surface heat flux on the thermal performance of the natural-convection phenomenon is taken into consideration. 2. experimental-setup the experimental-setup is designed and manufactured to cover the experiments of the present work as shown in figure (1). it consists of externally-finned tube vertically assembly inside an open ended square-section enclosure, voltage regulator, digital multi meter, and twelve channels data logger thermometer. the finned-tube assembly is fixed vertically into an acrylic sheet enclosure opened from top and bottom utilizing a plastic stand. it consists of tube with external diameter (d) of 28 mm, inner diameter (d) of 20 mm and length (l) of 200 mm and made from polished aluminum. two configurations of longitudinal rectangular fin, continuous and interrupted are made from the same material of tube with thickness (t) of 2 mm and fixed radially on the tube outer surface with different numbers and heights. the interrupted fin consists of three equal segments with length (lint) of 60 mm and the blank (b) between two segments is 10 mm as illustrated in figure (2). the inside surface of tube is heated electrically using heating coil of 500 w capacity and putted in a pyrex glass pipe with outer diameter of 20 mm to fit into the externallyfinned tube and joined to a voltage regulator model sako-tdgc2 size of 0.5 kva with rating of current 2 a and voltage from 0 to 250 v to control the supplied voltage for the electrical heater. a digital multi meter type victorvc890c+ having voltage range from 2 v to 750 v and current range from 20 ma to 20 a is utilized to gauge the supplied voltage and alternating current intensity passing to the heating coil. two teflon covers of 25 mm thickness are utilized to insulate and minimize heat lost from tube ends. the outer surface temperatures of tube are recorded using ten type-k calibrated thermocouples are distributed axially along the height of tube with equal distances as shown in figure (3) also two the same type-k calibrated thermocouples are utilized to read the temperatures difference through teflon covers in saad najeeb shehab al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 3040 (2017) 32 the two ends of the tube to estimate the heat conduction lost, and connected to a twelve channels data logger thermometer model btm4208sd of resolution 0.1 oc and rating from -100 oc to 1000 oc for type-k thermocouple prob. another digital type-k calibrated thermocouple is used to measure the surrounding air temperature inside an enclosure. a. sketch of an experimental-setup b. photos of an experimental-setup 1. vertical externally-finned tube 2. open ended enclosure 3. stand 4. voltage regulator 5. digital multi meter 6. data logger thermometer 7. heater 8. thermocouple wires 9. teflon covers 10. longitudinal rectangular fins. fig. 1. experimental-setup. a. tube with continuous fins b. tube with interrupted fins fig. 2. front views of longitudinal rectangular fins configuration. saad najeeb shehab al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 3040 (2017) 33 fig. 3. schematic diagram of front-section for vertical externally-finned tube assembly with thermocouples locations. 3. tests procedure and computation the present work is carried out for thirty different finned tubes. two types of external longitudinal fin, continuous and interrupted are utilized with fixed length (l) of 200 mm and thickness (t) of 2 mm for all fins. the interrupted longitudinal fin consists of three segments of fins with constant length (lint) of 60 mm and constant blank (b) of 10 mm, (lint/b= 6). five different numbers of each continuous and interrupted fins (n) namely, four, six, eight, twelve, and sixteen are fitted radially on the outer surface of heated tube with three different heights (h) 10, 20, and 30 mm. five varying values of surface heat fluxes (q) namely, 796, 1990, 3981, 5971, and 7962 w/m2 are utilized. the steady-state conditions for all experiments of the present work are attained from 90 to 120 minutes depending on the power input. the thermocouples readings have been registered when the difference of two readings of temperatures is ± ≤ 0.5 oc within 15 minutes approximately. then, the tube surface temperatures, surrounding air temperature inside an enclosure, input voltage, and current intensity passed to electrical heater are registered. the power input (qin) to the electrical heater into tube is computed as product of voltage (v) and input current (i) with power factor (cos ϕ): ��� = � � � � … (1) it’s transformed to heat energy and transferred from finned-tube to air surrounding by naturalconvection (qconv) and thermal radiation (qrad), moreover the thermal conduction lost (qcond) from ends of vertical finned-tube. then, ��� = ����� + ����+ ����� … (2) the loss of thermal radiation between outer surfaces of finned-tube and surrounding air inside an enclosure is calculated as follows [9]: ���� = � � ��� (����� − ��� ) … (3) where, ε = 0.05 is the emissivity of polished aluminum, f is the shape factor, ta is the surrounding air temperature, and tsav is the average outer surface temperatures of vertical tube. for interval from 0 to tube height (l) is computed as follows [9]: ���� = 1" # ��$ % & '( … (4) where, tsx is the local surface temperature. the heat conduction loss (qcond) is computed as thermal potential difference to thermal resistance. it’s found less than 3% of power input (qin) because the two thick covers of teflon are utilized in the finned-tube ends therefore can be neglected. then the heat transfer by natural-convection (qconv) can be computed as follows: ����� = � � � � − ���� … (5) it's also can be calculated from newton’s equation of cooling as follows [10, 11]: ����� = ℎ�� ��(���� − ��) … (6) the average natural-convection heat transfer coefficient (hav) can be calculated as: ℎ�� = � � � � − ���� ��(���� − ��) … (7) as is the surface area of finned-tube and computed as follows: tube with continuous longitudinal rectangular fins, �� = (./" − 01") + 202" … (8) tube with interrupted longitudinal rectangular fins, �� = (./" − 301"��4 ) + 602"��4 … (9) where, (d) is the outside diameter of tube, (l) is the height of tube or fin length, (h) is the fin height, (n) is the fins number, (t) is the fin thickness, and (lint) is segment length of interrupted fin. the heat flux (q) practiced on the finned-tube is computed from power input to heating element dividing by inner surface area of tube (a): 6 = ���� = �� � �.'" … (10) saad najeeb shehab al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 3040 (2017) 34 the average nusselt number (nuav) based on the external diameter of finned-tube (df) as characteristics length can be simply computed as: 08�� = ℎ�� /9: … (11) also average rayleigh number (raav) is computed from: ;<�� = =>�� ?> … (12) where, (pr) is prandtl number and (grav) is the average grashof number (grav): =>�� = @a /9b(���� − ��) cd … (13) and a = 1 �9⁄ … (14) air properties utilized in the experimental calculations are taken at film temperature (tf). it is computed as the arithmetic mean between the surrounding air temperature (ta) and average surface temperature (tsav) of the heated finnedtube in (k). the percentage error (e%) is evaluted as the percentage relative of absolute error (eab) to experimental value (vexp): f% = f�h�i$j k 100 = l�i$j − �����i$j l k 100 … (15) where, the absolute error (eab) is the absolute difference between experimental value (vexp) and correlated value (vcor) as follows: f�h = m�i$j − ����m … (16) the mean relative quadratic error (ē) is computed as: f̅ = op q�i$j − �����i$j rd� �st (u − 1)v w t d⁄ … (17) where, n is the data points number. 4. results and discussions the present work investigates experimentally effect of the fin configurations (continuous and interrupted), fin height, fin numbers, and the surface heat flux on the thermal performance for a heated finned-tube in vertical position into an enclosure with open ends. figures (4) to (7) illustrate the effect of number of fins on the temperatures difference (δt=tsav–ta) and average heat-transfer coefficient at different surface heat fluxes ranging from 796 to 7962 w/m2 and fin height (h= 30 mm) for continuous and interrupted fins. they are clear that the temperatures difference (δt) and average heat-transfer coefficient (hav) sharply increases as surface heat flux (q) increases. also, the average heat-transfer coefficient (hav) increases with increasing fins number (n) up to n= 12 and then decreases because the average surface temperature (tsav) decreases with fins number increasing up to n= 12 and then increasing when the thermal dissipation by natural convection for tubes with 16-fins becomes poor. additionally, figures (6) and (7) appear the values of average naturalconvection heat coefficient for interrupted fins are larger than those continuous fins because the interruptions in fin help to dissipate the growth of thermal boundary layer and interrupting it. fig. 4. effect of fins number on the temperaturestemperaturestemperaturestemperatures difference and surface heat flux for the continuous longitudinal fins. fig. 5. effect of fins number on the temperatures temperatures temperatures temperatures differencedifferencedifferencedifference and surface heat flux for the interrupted longitudinal fins. saad najeeb shehab al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 3040 (2017) 35 fig. 6. effect of fins number on the average heat average heat average heat average heat transfer coefficienttransfer coefficienttransfer coefficienttransfer coefficient and surface heat flux for the continuous longitudinal fins. fig. 7. effect of fins number on the average heat average heat average heat average heat transfer coefficienttransfer coefficienttransfer coefficienttransfer coefficient and surface heat flux for the interrupted longitudinal fins. figure (8) shows the behavior of average nusselt number (nuav) against fins number (n) for continuous and interrupted longitudinal fins at three varying fin heights (h= 10, 20, and 30 mm) and different surface heat fluxes. it is clear that the average nusselt number as a function of fins number at first increases up to a maximum value with the increase of fins number and then decreases. the optimum fins number (nopt) at maximizing average nusselt number is (nopt= 12) for all cases because the average surface temperature (tsav) decreases down to a minimum value with fins number increasing up to (n= 12) and then increases. this leads to bad naturalconvection thermal performance at fins number (n= 16). also it is clear that the values of average nusselt number for interrupted longitudinal fins are greater than those of continuous fins. the interrupted fins cause higher values of naturalconvection heat transfer coefficient because the interruptions help to dissipate the growth of thermal boundary layer along the height of tube and interrupting it, and this leads to a higher natural-convection heat transfer rate and improvement of natural-convection thermal performance. finally, it is clear that the average nusselt number enhanced when surface heat flux increases because the average convection heat transfer coefficient increases as surface heat flux increasing for all studied cases. figure (9) appears two correlations between average nusselt number and rayleigh number for two configurations of fin, continuous and interrupted at constant fins number (n= 12) and fin height (h= 30 mm) with a wide range of heat fluxes from 796 to 7962 w/m2. it is clear that the average nusselt number increases with increasing average rayleigh number. the following two experimental correlations for continuous and interrupted fins respectively; are concluded: 08�� = 6 k 10idd(;<��)b.�klt … (18) 08�� = 5 k 10itm (;<��)d.l&n … (19) figures (10) and (11) show comparisons of the correlated average nusselt numbers by eqs. (18) and (19) with those experimental of present data for tubes with continuous and interrupted longitudinal fins. they are clear that the percentage error (e%) of the experimental values located between +8% and -8% of correlated values for continuous fins and between +10% and -7% of correlated values for interrupted fins. also the mean relative quadratic errors (ē) are 0.168 and 0.119 for continuous and interrupted fins respectively. moreover, the experiment is carried out on a heated vertical smooth tube with same conditions to compare than morgan correlation: 08o = 0.48 (=>o ?>)&.dn … (20) this is valid for values of rayleigh number between 102 ≤ ra ≤ 107 as shown figure (12). it can be seen a good agreement in behavior. saad najeeb shehab al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 3040 (2017) 36 a. surface heat flux, q= 796 w/m2 b. surface heat flux, q= 1990 w/m2 c. surface heat flux, q= 3981 w/m2 d. surface heat flux, q= 5971 w/m2 e. surface heat flux, q= 7962 w/m2 fig. 8. behavior of verage nusselt number against fins number for different fin heights and surface heat fluxes. saad najeeb shehab al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 3040 (2017) 37 fig. 9. experimental analysis of present data for continuous and interrupted longitudinal fins with concluded correlations. fig. 10. comparison of correlated average nusselt numbers with those of the present experimental work for continuous longitudinal fins. fig. 11. comparison of correlated average nusselt numbers with those of the present experimental work for interrupted longitudinal fins. saad najeeb shehab al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 3040 (2017) 38 fig. 12. comparison the present experimental data for a heated smooth tube with morgan [1] correlation. 5. conclusions the present work has performed an experimental analysis of a heated vertical externally-finned tube inside an opened enclosure exposed to natural-convection. the tube is electrically heated under constant surface heat flux and steady-state conditions. continuous and interrupted longitudinal rectangular fins are utilized with different heights and numbers. the main conclusions can be drawn: 1. the average nusselt number is strongly a function of fins number, fin height, and surface heat flux. 2. the optimum value of fins number is (nopt= 12) for interrupted and continuous fins when maximizing average nusselt number. 3. the average nusselt number improves with increasing fin height and reaches to maximum values at (h= 30 mm). 4. the tube with twelve-interrupted longitudinal fins gave best natural-convection thermal performance in terms of average nusselt number about 20% higher than those continuous longitudinal fins. 5. two experimental correlations are concluded to expect the values of average nusselt number for interrupted and continuous longitudinal finned-tubes. nomenclature a internal surface area of finned-tube, (m2) as surface area of heat transfer, (m2) b interrupted length, (m) d internal diameter of tube, (m) d external diameter of tube, (m) df external diameter of finned-tube, (m) f shape factor g gravitational acceleration, (m/s2) gr grashof number h convection heat transfer coefficient, (w/m2.k) h height of fin, (m) i input current, (a) k thermal conductivity, (w/m.k) lint length of fin segment, (m) l height of tube or fin length, (m) n number of fins nu nusselt number pr prandtl number q surface heat flux, (w/m2) qcond rate of heat conduction loss, (w) qconv rate of natural-convection heat transfer, (w) qin power input, (w) qrad heat radiation loss, (w) ra rayleigh number t thickness of fin, (m) ta surrounding air temperature, (oc) tf film temperature, (k) ts surface temperature, (oc) v voltage, (v) greek letters δt temperatures differences, (k) cos ϕ power factor β volumetric coefficient of thermal expansion, (1/k) ε surface emissivity ν kinematic viscosity, (m2/s) σ constant of stefan-boltzmann, (5.67 × 10-8 w/ m2.k4) saad najeeb shehab al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 3040 (2017) 39 subscript symbols av average d based on tube external diameter opt optimum x local 6. references [1] morgan, v. t. “the overall convective heat transfer from smooth circular cylinders”, advances in heat transfer, elsevier ltd., vol. 11, pp. 199-264, 1975. [2] stewart, w. e. and verhulst, j. l. “experimental free convection from piping in district heating utilidors”, journal of energy resources technology, asme, 108 (2), pp. 173-178, 1986. [3] wu, j. m. and tao, w. q. “numerical computation of laminar natural convection heat transfer around a horizontal compound tube with external longitudinal fins”, journal of heat transfer engineering, vol. 28, issue 2, pp. 93-102, 2007. [4] kadhim, s. k. and abdulhussain, k. “experimental study of inclination angle and surface area effects for longitudinally finned cylinder on free convection heat transfer in an open enclosure“ , journal of engineering and technology, vol. 27, no. 5, pp.171-179, 2009. [5] dogan, a., akkus, s. and baskaya, s. “numerical analysis of natural convection heat transfer from annular fins on a horizontal cylinder“, journal of thermal science and technology, vol. 32, no. 2, pp. 31-41, 2012. [6] totala, b.t., shimpi, m.v., shete, n.l. and bhopate, v.s. “natural convection characteristics in vertical cylinder “ , international journal of engineering and sciences, vol. 3, issue 8, pp. 27-31, 2013. [7] niezgoda-zelasko, b. and zelasko, j. ”free and forced convection on the outer surface of vertical longitudinally finned tubes”, experimental thermal and fluid science journal, elsevier inc., vol. 57 . pp. 145-156, september 2014. [8] lee, j. b., kim, h. j. and kim, d. “experimental study of natural convection cooling of vertical cylinders with inclined plate fins”, energies journal, 9, 391, pp. 1-15, 2016. [9] cengel, y. a. “heat transfer: a practical approach“, mcgraw-hill companies, second edition, usa, 2008. [10] favre-marient, m. and tardu, s. “convective heat transfer“, john-wiley and sons, inc., first edition, usa, 2009. [11] bejan, a.“convection heat transfer“, johnwiley and sons inc., fourth edition, usa, 2013. )2017( 30-40، صفحة 4د، العد13دجلة الخوارزمي الهندسية المجلم سعد نجيب شهاب 40 تجريبيتحليل : مزعنف الطبيعي من أنبوب عمودي مسخنظاهرة الحمل سعد نجيب شهاب قسم الهندسة الميكانيكية / كلية الهندسة / الجامعة المستنصرية saad_najeeb16@ yahoo.comالبريد اللكتروني: ة ـالخالص ً للتنبؤ باألداء الحراري لظاهرة ةتجريبي يتناول هذا البحث دراسة الى الهواء المحيط داخل مغل;ف الحمل الطبيعي من أنبوب عمودي مزعنف خارجيا متقطع;ة بس;مك ثاب;ت وأرتفاع;ات وأع;داد مختلف;ة وّزع;ت بش;كل مس;تطيلة طولي;ة من الزعانف ، مستطيلة طولي;ة مس;تمرة و نوعان مفتوح النهايتين. أستخدم للقدرة الداخلة. تم دراسة تأثير شكل مستويات مختلفة ةشعاعي على السطح الخارجي لألنبوب المسخن. تم تسخين األنبوب كهربائيا من السطح الداخلي بخمس النتائج المستحصلة أن األنبوب ذا داء الحراري للحمل الطبيعي عمليا. أظهرتوالفيض الحراري لسطح األنبوب على األوارتفاعهاالزعانف الزعانف وعدد ً حراريأداء زعنفة طولية متقطعة يعطي تي عشرةاألثن بزع;انف نفس;ه ألنب;وب ل %٢٠ح;والي بلحمل الطبيعي بدالل;ة مع;دل رق;م نس;لت بنس;بة أكب;ر أفضل ل ا قورنت النتائج المقدّمة مع دراسة سابقة وأظهرت تقارباً ب بزعانف طولية مستمرة ومتقطعة. وألنابيمستمرة. أستنبطت عالقات عملية للتنبؤ بمعدل رقم نسلت جيداً. (microsoft word \310\324\355\32198-110) analysis the surface morphology of the porous media by using atomic force microscope technique bashir y. sherhan al-zaidi department of chemical engineering/ university of technology/ membrane technology research email: 80193@uotechnology.edu.iq (received 11 april 2017; accepted 10 july 2017) 7.007https://doi.org/10.22153/kej.2017.0 abstract an atomic force microscope (afm) technique is utilized to investigate the polystyrene (ps) impact upon the morphological properties of the outer as well as inner surface of poly vinyl chloride (pvc) porous fibers. noticeable a new shape of the nodules at the outer and inner surfaces, namely "crater nodules", has been observed. the fibers surface images have seen to be regular nodular texture at the skin of the inner and outer surfaces at low ps content. at ps content of 6 wt.%, the nodules structure was varied from crater shape to stripe. while with increasing of ps content, the pore density reduces as a result of increasing the size of the pore at the fiber surface. moreover, the test of 3d-afm images shows that the roughness of both surfaces of fibers seems to be decreased with ps content. alternatively, the fibers pure water permeability (pwp) has been declined with decreasing of fiber roughness. keywords: polymeric surface; porous surface; additive; surface morphology; afm . 1. introduction today, afm is used with extremely range of applications; from normal fantasy of morphology to advanced inspection of surface properties at the array of sub-nanometer [1]. the nodules and nodular aggregates size in addition to the roughness and size of the pore with dispersion of the pore diameter would be able to measure via afm technique [2-14]. the pore sizes of the polysulfone (psf) surface were measured through afm and scanning electron microscope (sem) techniques by means of researchers kim and coworkers [4]. they observed that the afm was more precise in comparison with the results obtained by sem technique. moreover, pore diameter, nodule size and roughness of psf fibers surface were also evaluated by rafat et al. [5] using sem and afm techniques. barzin et al., and otero et al. [6,9] had tested the surface roughness of polyether sulfone, pes fibers, through afm technique. while the roughness and the size of nodular for external surface of cellulose acetate butyrate, cab fiber, had previously been tested [13]. furthermore, a new method to analyze the extracted data from the afm images using matlab software was found by el-hadidy et al. [14]. additionally, razali et al [15] achieved the distribution of the pore diameter of pes / polyaniline (pani) nano-particles membranes by afm technique. concerning the specification and characterization of the structural morphology of the membrane that might be utilized for membrane distillations applications, shirazi et al. [16] had used afm technique for measuring the roughness, diameter, and distribution of the pore diameter of membrane separated from various hydrophobic polymeric materials. according to the importance of the structural morphology (i.e., membrane roughness) on the performance of the fibers, which it means membrane with low fouling, the membrane properties were investigated in this work. some researchers focused their work on the impact of the roughness of the membranes on the performance, for example, chunget. al., [17] had demonstrated the shear rate impact on the pes al-khwarizmi engineering journal al-khwarizmi engineering journal,vol. 13, no. 4, p.p. 98110 (2017) bashir y. sherhan al-zaidi al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 98110 (2017) 99 morphology of ultrafiltration (uf) membranes by using afm. it was reported that the pure water flux of the membranes was proportional to the mean roughness, as the lower mean roughness was led to higher separation factor. from the preceding effort, improvement in hollow pvc/ps fibers permeability was also investigated by using afm technique [18]. plenty of workers were utilized the afm technique for measuring the characteristic of the fiber surface, but indeed the workers didn't show the sufficient concern of afm technique in their efforts. thus, the significant goal of this effort is to inspect the impact of ps content in blend solution through the use of afm technique on fiber surface properties. 2. experimental procedure 2.1. blend hollow fiber pvc-ps fibers with different ps contents (1 to 6% by weight) at14 wt% pvc with dimethylacetamide (dmac) as solvent were used in the present work and assigned as ps1, ps2, ps3, ps4 and ps6. the parameters and conditions of the spinning process of the fibers and all details were explained elsewhere [18]. 2.2 fibers permeability (pwp) pwp of the fibers was commonly evaluated after constructed of the fibers cells. each cell has six fibers of 20 cm long. ends of the cell of fibers bundles might be agglutinant by utilizing an epoxy resin into two stainless steel tees. figure 1 presents the ultra-filtration (uf) system. by using 1 bar as a trans-membrane pressure and 26°c temperature of de-ionized water, the experiments were orderly achieved in fibers cell. pwp could be evaluated utilizing the operating correlation below: ap q pwp w ∆ = ... (1) where δp is the pressure gradient across the fiber (bar), and a is effective area of fibers (m2), and qw is the volumetric flow rate (l/h). fig. 1. schematic diagram of the uf membrane experimental unit; 1: feed tank, 2: pump, 3: flow meter, 4: permeate tank, 5: hollow fiber module, 61, 2: gauge pressure, 7-1, 2, 3: valve. 2.3. fiber characteristic by afmtechnique by employing an afm (angstrom advanced inc., aa3000 model (usa)) and the use of contact mode through appropriate tip (made from silicon material), the blend fibers might succumb to the surface analysis. the measurements were inclusive an assessment of the topography and the profiling force as well as deflection and its amount. the software imager version 4.31 was exercised to evaluate the statistical distribution of the pore diameter for the outer fibers surfaces. in addition, depending on the afm results, roughness parameters could be estimated. based on these different roughness parameters, the surfaces of the blend fiber were inspected, for instance, the root mean square of z values [rms(nm)], the mean roughness [ra(nm)], the vertical space between the lowest ravines, and also the highest peaks [rmax]. fibers roughness is important features of the surface of the fiber, where it owns a strong impact on fouling as well as concentration polarization of the fibers, as it had demonstrated by chung et. al. [17]. the standard shifting of pixel amounts from the plane are introduced as the mean roughness, also it could be estimated via utilizing the correlation below:    = ∫ ∫ y xl l yxa dxdyyxfllr 0 0 ),(1 ... (2) here f(x,y) means the surface relating toward the center of the plane, also ly and lx were define as a surface dimensions. rms (nm) is surface roughness that could either be measured statistically or be estimated theoretically as the bashir y. sherhan al-zaidi al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 98110 (2017) 100 shifting of all pixel amounts from the mean pixel amount z as follows: ( ) ( )( )11 ,1 ,1 2 , −− − = ∑ = = ij zz r jy ix yx ms ... (3) here zx,y is the height image pixel respect to the height of the plane center z x, y and i and j are the pixels number in the directions of x&y [19]. it is important to saying that the fiber mean roughness is a relative value owing to the reliance of the roughness on the bending [20]. 3. results and discussion 3.1 afm analysis afm pictures with 3-dimensional and 2dimensional view of the inner surface at 2.065 µm x 2.065 µm fibers area are presented in figure 2. crater nodules could be observed with different sizes at the inner surface, and this shape of nodules was not mentioned yet in the literature. also, the crater nodules were semi-regularly appeared on the surface as presented in figure 2a to figure 2c. furthermore, the size of the crater nodules at the inner surface were increased with increasing of ps content in the blend solution to 3 wt.%. more rising of ps content such as, 4 and 6 wt.% is result to the nodules nip up with each other, therefore, new nodules shape could be observed on the fiber surfaces, namely "stripe". the nodules in the shape of stripe are randomly distributed among the nodules with crater shape as depicted in figures 2d and 2e. moreover, afm pictures with 3dimensional and 2-dimensional view of the outer surface at area of 2.065 µm x 2.065 µm for fibers made by using different ps contents in blend solution is presented in figure 3. the nodules in crater shape are become visible with increasing the ps content from 1 to 3 wt.% in blend solution as illustrated in figures 3a, 3b and 3c. more mounting in ps content up to 4 wt.% within blend solution is results in combination of the nodules [see figure 3d]. ps with content of 6 wt.%, results to completely turn out the nodules structure in the shape of the crater to the nodules in the shape of stripe as it can be distinguished in figure 3e. bashir y. sherhan al-zaidi al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 98110 (2017) 101 fig. 2. three-dimensional and top view afm pictures of the inner surface of the hollow fiber blend membranes: (a) ps1, 1 wt.%, (b) ps2, 2 wt.%, (c) ps3, 3 wt.%, (d) ps4, 4 wt.%, (e) ps6, 6 wt.%. bashir y. sherhan al-zaidi al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 98110 (2017) 102 fig. 3. three-dimensional and top view afm pictures of the outer surface of the hollow fiber blend membranes: (a) ps1, 1 wt.%, (b) ps2, 2 wt.%, (c) ps3, 3 wt.%, (d) ps4, 4 wt.%, (e) ps6, 6 wt.%. bashir y. sherhan al-zaidi al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 98110 (2017) 103 the phenomenon behind such observation for outer and inner surfaces can be attributed to the exchange rate of the water from the internal and external coagulation baths with solvent (dmac) in blend solution. the speed of the interchange rate is strongly dependent upon the difference in solubility parameter (sp) for pvc and ps with dmac, for example, the variation in sp (δδ) between dmac as well as pvc was found to be 7.5 (mpa)0.5, whereas regarding dmac as well as ps, the (δδ) was obtained to be 14.7 (mpa)0.5 [21,22]. freezing process of polystyrene (ps) throughout the nascent fiber formation seems to be faster than that of pvc. this phenomenon can be described from the other side according to the increment of ps content in blend solution, which leads to slow blend solution and water de-mixing process. on account of the variation in solubility parameter between dmac with pvc and ps, the ps nodules combined with each other quicker in comparing with that can be observed in pvc nodules during the formation process of the fiber; hence the structure of the stripe nodules was nearly formed and spread regularly on the surface. in fact, the mechanism of the phase separation has a significant effect on the morphological structure of fibers synthesized by the phase inversion technique [4,23]. by the phase separation method the polymer solution can be separated into two phases: polymer poor phase, that represents the cavities (e.g., pores); and polymer rich phase (membrane matrix). here, the retard in the solventwater de-mixing process can be take place throughout the configuration of the nascent fiber at the inner surface. perhaps few amount of nonsolvent (e.g., water) within internal coagulant was the main foundation for this phenomenon, which is guided to enhance of dmac content through the internal coagulant and therefore led to obtain a layer with looser skin. while the instantaneous solvent-water de-mixing process could be occurred, ones the nascent fiber being into direct connection with the water at the outer surface (i.e., external coagulation bath). it is obvious that the phase separation is introduced as a converted for the polymer mixture into two phases; the first one concerning the rich phase (solidified polymer), which demonstrates the matrix of the membrane but the second concerning with polymer poor phase, which exhibits the sinus as it had already been reported by kesting [23]. 3.2. pore and pore size distribution the mean diameter of the pore for both outer and inner surfaces of the blend fiber can be outlined in tables 1 and 2, and the pore density is also illustrated in figure 4. the pore density is diminished while the mean pore size elevated with increasing of ps content in blend solution as shown in figure 4. principally, this behavior is due to the quantities of polymers in the blend solution. increment in the viscosity of the blend solution with increasing of ps content led to delay the movement of the solvent in the blend solution toward the water. consecutively, this behavior might be gone ahead to make low pore density and large pore size at the fiber surface. fig. 4. effect of ps compositions on the pore density of the hollow fiber blend membranes. furthermore, the blend process of dmac as a solvent and both ps and pvc as a membrane blend can be classified as a homogeneous process since the two polymers have a non-polar character. as a consequence, it is possible to obtain a physical mixing of the polymers. this is the second reason might be backing the aforementioned observation [25]. dong-liang et al. [25] had detected that an increase in the content of the polymer within the casting solution would be led to decrease the density of the pores. 1 2 3 4 5 6 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 outer surface inner surface p o re d e n s it y ( p o re s /m 2 )( x 1 0 -9 ) ps composition (wt.%) bashir y. sherhan al-zaidi al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 98110 (2017) 104 table 1, mean pore size and mean roughness of the inner surface of the hollow fiber blend membranes membran e code pvc/ps/dmac solution (wt.%) mean pore size (nm) inner surface roughness (2065×2065 nm2) mean roughness 1(ra) (nm) the root mean square of z values 2(rms) (nm) maximum roughness 3(rmax) (nm) ps1 14:1:85 104.16 10.7 12.4 45.2 ps2 14:2:84 109.28 10.2 11.9 43.9 ps3 14:3:83 138.16 8.45 9.87 36.9 ps4 14:4:82 140.82 7.64 8.86 28.9 ps6 14:6:80 195.98 5.47 6.30 19.1 1 (ra): the mean value of the surface relative to the center plane. 2 (rms): the root mean square of z values. 2 (rmax): maximum roughness (vertical distance between the highest peaks and the lowest valleys). table 2, mean pore size and mean roughness of the outer surface of the hollow fiber blend membranes. membrane code pvc/ps/dmac solution (wt.%) mean pore size (nm) outer surface roughness (2065×2065nm2) mean roughness (ra) (nm) the root mean square of z values (rms) (nm) maximum roughness (rmax)(nm) ps1 14:1:85 109.19 10.5 12 35.1 ps2 14:2:84 117.86 8.64 10.1 34.6 ps3 14:3:83 141.12 7.12 9.6 32 ps4 14:4:82 142.86 4.47 5.19 17.8 ps6 14:6:80 184.48 3.48 4.03 14.2 figure 5 presents the impact of ps content on the distribution size of the pores of fiber inner surface. the size distribution of the pores of the fibers is in the range of 75 and 205 nm, while the size frequency of the pores is in between of 75 and 85 nm, which is above 17.28% and 17% respectively of the prepared blend fibers from ps content of 1 wt.% as demonstrated in figure 5. the distribution of the pore size of the synthesized fibers from ps of 2wt.% is in the range of 70 and 340 nm and the frequency of the pore sizes is 75, 85, and 95 nm, which is approximately 14, 12, and 11% respectively. more increment in the ps content of about 3 wt.%, makes the distribution of the pore size to be in the range of 120 and 210 nm and around 25.64% highest frequency of the 120 nm pore size as given in figure 5. likewise for ps content of about 4wt.% in blend solution, most pores are seen in the size of 110 nm and equivalent to frequency of 19%. also for ps content of about 6 wt.%, the distribution of the pore size becomes in the range of 160 to 440 nm and in the size of 180 nm with 19% pores frequency is found in that case. in figure 6, impact of ps content on distribution of the pore diameter of the fibers outer surface has been depicted. here it can be seen that the distribution of the pore diameter is in the range of 70 to 310 nm and the frequency at pore size of 90 nm is about 25% for the prepared blend fiber with ps of 1 wt.% inside blend mixture. bashir y. sherhan al-zaidi al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 98110 (2017) 105 fig. 5. pore size distributions of the inner surface of the hollow fiber blend membranes. above and beyond, the size distribution of the pores transferred to the right and initiated of 95 to 175 nm as well as the frequency of the pore size at 110 nm is approximately 18.44%, as a result of the rising the content of ps to 2 wt.%. for ps content 3 wt.%, the distribution in the pore size seems to be more shifted to the right with pore size range of 120 and 190 nm and the frequency of the pores size at 130 nm is 33% [see figure 6]. by using 4 wt.% ps in blend mixture, the distribution of the pore size is turned out to be in the range of 100 and 280 nm with the same pore size frequency at each of 100, 110, and 120 nm. additionally, the distribution of the pore size is appeared in the wide range (110 and 400 nm) at ps content of 6 wt. % in blend mixture. pores in the size of about 130 nm have a frequency of 33%, the indication from these results can be confirmed that the distribution of the pore size of both surfaces are in the narrow range of all contents of ps in blend mixture. the truth of this phenomenon is due to the perfect physical mixing for dmac solvent with the two polymers, owing to the character of non-polar ps and pvc as it has already been mentioned in the preceding sections. 80 100 120 140 160 180 200 0 2 4 6 8 10 12 14 16 18 p o re s iz e d is tr ib u ti o n ( % ) pore diameter (nm) 1 wt.% ps 75 100 125 150 175 200 225 250 275 300 325 0 2 4 6 8 10 12 14 16 p o re s iz e d is tr ib u ti o n ( % ) pore diameter (nm) 2 wt.% ps 120 130 140 150 160 170 180 190 200 210 0 5 10 15 20 25 p o re s iz e d is tr ib u ti o n ( % ) pore diameter (nm) 3 wt.% ps 100 120 140 160 180 200 220 240 260 280 0 2 4 6 8 10 12 14 16 18 20 p o re s iz e d is tr ib u ti o n ( % ) pore diameter (nm) 4 wt.% ps 150 200 250 300 350 400 450 0 5 10 15 20 25 30 p o re s iz e d is tr ib u ti o n ( % ) pore diameter (nm) 6 wt.% ps bashir y. sherhan al-zaidi al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 98110 (2017) 106 fig. 6. pore size distributions of the outer surface of the hollow fiber blend membranes. likewise, the cumulative distributions of pore sizes for both surfaces of the blend fibers are shown in figure 7 and figure 8. it is significant here to observe that the pore sizes cumulative distributions of outer and inner surfaces are moved toward the right side along with the increasing of ps contents in blend mixture. here it should pay particular attention to the strong impact of the ps content on the dispersion of the pore size over the fibers surface. the observed phenomenon perhaps impute to the alteration in the rate of diffusion between the non-solvent in the internal and external coagulation baths and the solvent in the blend mixture. table 1 and table 2 summarized the mean roughness of the blend fibers in terms of rm, rmax and ra, for both surfaces of the blend fibers as a function of ps content in blend mixture. it can be noticed that the results extracted from tables show that an increase in the ps content inside the blend mixture leads to a decrease in the mean roughness of the blend surface. knurl size of ps formed at both surfaces as a consequence of ps agglomeration can be fixed as a main factor of the mean roughness reduction in the blend fibers. a good agreement of this watching was found in the results presented by al-salhy and coworkers [26]. besides, sotto and co-workers [27] had reported that as the pes content in casting solution increases, the roughness is decreased. the authors were found that a very compact nodule was formed with smooth surface as a reason of increasing the pes content. 100 150 200 250 300 0 5 10 15 20 25 p o r e si ze d is tr ib u ti o n ( % ) pore diameter (nm) 1 wt.% ps 100 120 140 160 0 2 4 6 8 10 12 14 16 18 p o re s ia e d is tr ib u ti o n ( % ) pore diameter (nm) 2 wt.% ps 120 130 140 150 160 170 180 190 0 5 10 15 20 25 30 35 p o re s iz e d is tr ib u ti o n ( % ) pore diameter (nm) 3 wt.% ps 100 120 140 160 180 200 220 240 260 280 0 2 4 6 8 10 12 14 16 18 p o re s iz e d is tr ib u ti o n ( % ) pore diameter (nm) 4 wt.% ps 150 200 250 300 350 400 0 2 4 6 8 10 p o re s iz e d is tr ib u ti o n ( % ) pore diameter (nm) 6 wt.% ps bashir y. sherhan al-zaidi al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 98110 (2017) 107 fig. 7. accumulative (%) of the pore diameter at the inner surface of the hollow fiber blend membranes. fig. 8. accumulative (%) of the pore diameter at the outer surface of the hollow fiber blend membranes. 3.3. water permeability finally, the influence of roughness of the outer surface of the blend fibers on the pwp is illustrates in figure 9. from this figure, it is perceived that as an increase the mean roughness of the outer surface, the pwp of blend fibers is increased. the behavior of this result is on account of the density expansion of the pores at the blend fiber surface as previously established in figure 4. accordingly, it is significant to deduce here the proportional relationship between the pore density and the mean roughness of the blend fibers that is sequentially influenced the blend fibers pwp. chung et al. [17] discovered that the pwp of the pes fiber commensurate to the surface roughness. fig. 9. effect of mean roughness of the outer surface of hollow fiber membranes on the pure water permeability (pwp). 4. conclusions afm-technique is used in this work for the purpose of analysis test the influence of ps concentration, as a second material, on the structure morphology and/or structure properties of the pvc fiber surfaces. the extracted conclusions can be summarized below: • the polymer concentration in blend mixture has a major impact on the outer and inner surface morphology of pvc fibers. • noticeable a new nodules shape namely as "crater nodules", is obtained at both outer and inner surfaces. • structure of the nodules is seen to be shifted from the nodules in the shape of crater to stripe shape with increasing of the content of ps inside the blend mixture to about 6 wt.%. the behavior of this phenomenon is fundamentally because of the incorporation of the nodules of ps itself quicker than the nodules of pvc throughout the formation of blend fibers. • decreasing pore density and increasing mean size of the pores due to the increasing of the ps contents. this surveillance can be analyzed by means of the increase of the viscosity of the blend polymers mixture. • from the extracted results it was detected that the size distribution of the pores of outer as well as inner surfaces seems to be narrow for all the used contents of ps owing to the perfect physical mixing of the dmac with two polymers. • decrease of the mean roughness is due to the increase of ps content in blend mixture. this observation possibly because of the knurl of ps 50 100 150 200 250 300 350 400 450 0 20 40 60 80 100 1 wt.% ps 2 wt.% ps 3 wt.% ps 4 wt.% ps 6 wt.% ps a cc u m u la ti v e (% ) pore diameter (nm) 50 100 150 200 250 300 350 400 0 20 40 60 80 100 1 wt.% ps 2 wt.% ps 3 wt.% ps 4 wt.% ps 6 wt.% ps a c c u m u la ti v e ( % ) pore diameter (nm) 3 4 5 6 7 8 9 10 11 94 96 98 100 102 104 106 108 110 112 p w p ( l/ m 2 . h . b a r) mean roughness (nm) bashir y. sherhan al-zaidi al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 98110 (2017) 108 formed on the surface as a result of the ps agglomeration. • the pwp of the blend fibers is seen to be increased with increasing the outer surface roughness, which is caused by increment of blend fiber pore density. acknowledgements i would like to acknowledge the assistance of the laboratory staff and especially prof. dr. qusay f. al-salhy at the membrane technology research unit within the chemical engineering departmentuniversity of technology, where the majority of the experimental work had been completed 5. references [1] n. n. li, a. g. fane, w. s. winston ho, t. matsuura, john wiley & sons, inc., hoboken, new jersey, 2008. [2] k.c. khulbe, b. kruczek, g. chowdhury, s. gagne, t. matsuura, surface morphology of homogeneous and asymmetric membranes made from poly (phenylene oxide) by tapping mode atomic force microscope, j. appl. polym. sci. 59 (1996) 1151-1158. [3] m. hirose, h. ito, y. kamiyama, effect of skin layer surface structures on the flux behavior of ro membranes, j. membr. sci. 121 (1996) 209215. [4] j.y. kim, h.k. lee, s.c. kim, surface structure and phase separation of polysulfone membrane by atomic force microscopy, j. membr. sci., 163 (1999) 159–166. [5] m. rafat, d. de, k.c. khulbe, t. nguyen and t. matsuura, surface characterization of hollow fiber membranes used in artificial kidney, j. appl. polym. sci., 101 (2006) 4386–4400. [6] j. barzin, c. feng, k.c. khulbe, t. matsuura, s.s. madaeni, h. mirzadeh, characterization of polyethersulfone hemo-dialysis membrane by ultra-filtration and atomic force microscopy, journal of membrane science 237 (2004) 77– 85. 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[15] n. faizah razali, a. mohammad, n. hilal, c. peng leo, j. alam, optimization of polyethersulfone / polyaniline blended membranes using response surface methodology approach, desalination 311 (2013) 182–191. [16] m. a. shirazi, d. bastani, a. kargari, m. tabatabaei, characterization of polymeric membranes for membrane distillation using atomic force microscopy, desal. water treat., (2013) 1–6. [17] t. shung chung, j. jun qin, a. huan, k. chua toh, visualization of the effect of die shear rate on the outer surface morphology of ultrafiltration membranes by afm, journal of membrane science 196 (2002) 251–266. [18] q. f. alsalhy, hollow fiber ultra-filtration membranes prepared from blends of poly (vinyl chloride) and polystyrene, desalination 294 (2012) 44–52. bashir y. sherhan al-zaidi al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 98110 (2017) 109 [19] s. holger, v. g. julius, scanning force microscopy of polymers, springer berlin heidelberg, 2010. [20] k. c. khulbe, t. matsuura, characterization of synthetic membranes by raman spectroscopy, electron spin resonance, and atomic force microscopy a review, polymer, 41 (2000) 1917-1935. [21] j. brandrup, e. h. immergut, polymer handbook [m], 3rd edition wiley, new york, 1989. [22] j. y. lai, f. c. lin, c. c. wang, d. m. wang, effect of non-solvent additives on the porosity and morphology of asymmetric tpx membranes, j. membr. sci. 118 (1996) 49. [23] r. e. kesting, synthetic polymer membranes, mcgraw-hill, new york, 1972. [24] v. thirtha, r. lehman, t. nosker, morphological effects on glass transition behavior in selected immiscible blends of amorphous and semi-crystalline polymers, polymer 47 (2006) 5392–5401. [25] d. wang, k. li, w. k. teo, preparation and characterization of polyvinylidene fluoride (pvdf) hollow fiber membranes. j. membr. sci., 163(1999) 211-220. 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[27] a. sotto, a. rashed, r. xin zhang, a. martínez, l. braken, p. luis, b. van der bruggen, improved membrane structures for seawater desalination by studying the influence of sub-layers, desalination 287 (2012) 317–325. )2017( 98-110، صفحة 4، العدد13دجلة الخوارزمي الهندسية المجلم بشير يوسف شرهان 110 طة استخدام مجهر القوة الذرياسء مورفولوجيا السطوح المسامية بوأستقصا بشير يوسف شرهان قسم الهندسة الكيمياوية/ الجامعة التكنولوجية bashiryoush1974123@yahoo.com :البريد االلكتروني الخالصة ل ذات ابعاد احادية او ثنائية او ثالثية في داخ ةوي فتحات على سطحها تقود الى شبكوالتي تحت وفحصها سطوح المواد المسامية يتعلق البحث بدراسة راسة تاثير محتوى البولي ستايرين . ان هذه التقنية تم استخدامها في البحث لدtechnique-(afm( تقنية مجهر القوى الذريالبناء الهيكلي لها وذلك باستخدام ميزوتم مالحظة شكالً لعقد متغير مورفولوجيا السطح المسامي. عن طريقلي فنيل كلورايد المسامية على خواص السطوح الخارجية والداخلية اللياف البو .crater nodules"": على السطوح الخارجية والداخلية عرفت علميا باسم كان منتظما عند استخدام ةوالخارجي ةتركيب العقد على السطوح الداخلي من خالل مجهر القوة الذري اوضحت ان ةالمستنبطحيث ان صور االلياف ان زيادة "stripe". " الىcraterمن مادة البولي ستايرين تم مالحظة تغير الشكل الهيكلي للعقد من " %٦محتوى قليل من البولي ستايرين. وعند تركيز ى االبعاد لمجهر القوى الذري دلت كذلك عل ةعلى سطوح االلياف. الصور ثالثيهالي ستايرين ادى ايضا الى نقصان كثافة المسامات مع زيادة حجممحتوى البو . لذلك فمعدل نفاذية الماء عبر االلياف قل مع نقصان خشونة السطوح ةوالخارجي ةالى نقصان خشونة السطوح الداخلي ان زيادة محتوى البولي ستايرين ادى (microsoft word 84-93 \307\337\321\343 \346\341\355\313 \346\323\314\354) al-khwarizmi engineering journal al-khwarizmi engineering journal,vol. 13, no. 1, p.p. 8493 (2017) antibacterial activity of electrospun silver nitrate /nylon 6 polymeric nanofiber water filtration mats akram raheem jabur* laith kais abbas** saja aqeel moosa*** *,**,***department of materials engineering / university of technology *email: akram.jabut@gmail.com (received 13 july 2016; accepted 9 october 2016) .22153/kej.2017.10.001https://doi.org/10 abstract bacterial water pollution is a genuine general wellbeing concern since it causes various maladies. antimicrobial nanofibers can be integrated by incorporating nanobiocides, for example, silver nanoparticles into nanofibers. nylon 6 was dissolved in formic acid at a concentration of (25 wt. %) and tough antibacterial (agno3/nylon) nanofibers were produced utilizing electrospinning system. polymer solution was tested before accomplishing electrospinning process to acquire its surface tension, electric conductivity and viscosity, where every one of those parameters increased relatively with increasing concentration of (agno3) additions. sem and edx spectra were utilized to focus on the morphology, surface elemental membrane, fibers and porosize diameters. the resulted nanofiber membrane has an average fiber diameter of 139 nm for pure nylon 6 and 247 nm for (1.2 wt. % agno3/nylon). the resultant polymer membrane was then tested for their ability to destroy microorganisms in water; antimicrobial tests showed that the prepared nanofibers have a high bactericidal effect against escherichia coli bacteria with inhibition zone (10 mm) and antibacterial activity (99%). likewise, these results highlight the potential utilization of these nanofibrous mats as antimicrobial agents. keywords: antibactrial, electrospinning, nanofiber, water purification filters. 1. introduction the development of energy-efficient water treatment technology has become an important area of research as it offers a solution to the increasingly limited water supplies available to the world’s growing population and industry [1-3]. nanofibers have perfect filtration properties because of different polymers that can be used to produce nanofibers, functional molecules and chemical groups can be added to the nanofibers which made nanofibers applicable to sanitation and purification of water. antimicrobial nanofibers synthesized by incorporating nanobiocides such as silver nanoparticles into the nanofibers (by reduction silver nitrate). the synthesis of nanofibers consists of metal nanoparticles is well investigated because of the benefits included with the joining of functional properties of metal nanoparticles with the widely applicable properties of nanofibers [4]. for a generation of nano-ag-bearing nanofibres, silver can be added to the spinning solution either in form of nanoparticles [5] or as silverions which can be reduced to nano-ag by a corresponding post-treatment [6 , 7]. reduction of ionic silver can be achieved (i) by subsequent uv-irradiation of the fiber webs, (ii) by the use of reducing agents [8] and (iii) by heat-treatment of the nanofibres [9]. investigates in the previous years demonstrated that silver-containing electrospun nanofibers have pulled in consideration as another sort of antimicrobial material [10, 11]. electrospinning process utilized for creation of nanofiber mat with high surface areas to volume aspect ratio, and high porosity. the process has appeared to be akram raheem jabur al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 8493(2017) 85 reasonable for production manufacturing of low-cost mass production [12, 13, 14]. silver is extensively used as biocidal agent which is successful versus bacteria, fungi and viruses yet are non-harmful to man cells [15, 16]. the electrospun nanofibers with high specific surface area and thinness combined with the biocidal effectivity of silver nanoparticles made an excellent antimicrobial material [17, 18]. the reduction of aldehyde groups from (agno3) forms a metallic silver. the formic acid goes about as the solvent for (nylon 6) and a reducing agent for (agno3). the (nylon 6) solution in formic acid, trailed by silver nitrate were slowly included dark and opaque condition, with obvious visible bubbles have been appeared. the reaction mechanism in figure (1) can clarify the past segment. at the point when silver nitrate is included into the formic acid solution of (nylon 6), it is reduced into metallic silver by the aldehyde group in the formic acid molecule. simultaneously, the oxidation occurs in the aldehyde group and form carboxyl group. then the carbonic acid form that is unsteady and rapidly dissociates into carbon dioxide and water [19]. the advantage of this system is the in situ stabilization of silver nanoparticles. initially, ions are reduced to metallic silver, immediately atoms are aggregated into clusters. these clusters have very small size and high surface energy, which leads them to form larger particles. usually a surfactant agent is added to stabilize silver and avoid further aggregation [20, 21]. when antimicrobial agents are needed, silver is considered best material, and its forms are a strong antimicrobials against diverse bacterial kinds. the precise mechanism of how silver take part in the distortion of bacteria is regrettably yet unclear. silver nanoparticles adhere to the microbial cell membrane where it interacts with sulfur-containing proteins. nanoparticles can also penetrate the cell membrane, where it interacts with phosphorous-containing dna and attack thiol groups of respiratory chain enzymes, inhibiting cell division and respiration, finally leading to cell death [22 , 23]. however, mostly it is supposed that sliver basically makes denaturation and oxidation for cell organelles which drive to suppress the cell segmentation. as known, the inhibition zones formed near the contact part when the critical amount of antibacterial agents in touch with bacterial strains[24]. the object of this study is to prepare antimicrobial (nylon 6) nanofibers containing silver nanoparticles by electrospinning technique. the solvent and polymer in this research act as reducing and a stabilizing agent, respectively. fig. 1. chemical mechanism of silver reduction by formic acid [18]. nylon 6 is chosen due to it is one of the most used conventional fibers materials. finally, demonstrating antibacterial properties for use in water disinfection (escherichia coli (e. coli)) was chosen in this study as indicators of fecal contamination. 2. experimental part 2.2. materials nylon 6, formic acid, and silver nitrate (agno3) were bought from (sigma-aldrich co. (usa)). all materials were utilized without further purification. 2.3. preparation of nylon 6/agno3 electrospinning solution nylon 6 was dissolved in formic acid at a concentration of (25 wt. %) and was stirred at (30-40 º c) for (3) hrs to acquire a transparent homogeneous solution. the solution was then cooled to room temperature under stirred, and a specific amount of agno3 (0.2 to1.2 wt% in solution) was included. the solution was avoided from light and stirred under room temperature for (3) hrs to insure the complete reduction of (agno3). 2.4. electrospinning the prepared electrospun solution was gathered in (10 ml) syringe furnished with a (22 gauge) stainless steel needle tip. the electrospinning process was conveyed at voltage (25 kv), flow rate (0.5 ml/hr), (22) gauge (0.7 mm) needle of electrospinning, and (15 cm) separation distance between electrode. the electrospinning process took four hour time and these parameters will be fixed for every solution in this work. the electrospinning process was carried out by a (bio-electrospinning/ electrospray system esb-200, provided by nano nc, south korea), as shown in figure (2). akram raheem jabur al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 8493(2017) 86 2.5. characterizations characterization of polymer solution before electrospinning and (sem, edx) of membrane after spinning process: pure and (agno3 /nylon 6) polymeric solution viscosity were measured by a viscometer of type (dv-iipro) brook, solution electrical conductivity was measured using the electrical conductivity device of model (c and 7110 inolab) and surface tension also measured using a surface tensiometer model (jyw-200a laryee technology co). fig. 2. electrospinning device: asyringe pump instruction, bcollector plate, cpower supply, d-touch control board. fig. 3. photographs of (nylon 6) nanofibrous web (a) without (agno3) and (b) nylon 6 with (agno3). the surface morphology of nanofibers and measurement for the overages fibers diameters and process was observed using scanning electron microscope (model: vega3 lm -tescan)), by mode of low variable pressure, which must be enough and not need any more of sample gold ion sputtering coating to a chive conductivity surface for (sem) test. antibacterial assessment assay: a. antibacterial activity test (disc diffusion method): the bacteria were grown aerobically in nutrient broth at (37 ºc for 12 hrs) [25]. the cells were washed and suspended in distilled water, reaching the final concentration of (10 6 cfu/ml). the antimicrobial susceptibility of (nylon 6 nanofibers / additives) was evaluated using the disc diffusion method. muller hinton agar was prepared from a commercially available dehydrated medium according to manufacturer’s instructions. the dried surface of muller hinton agar plate was inoculated with e.coli by swabbing over entire the sterile agar surface. two forms of sterilized samples of nanofiber membrane (one containing additive and one without additive, used as control) were cut into small standard circles (6mm in diameter) for each circle and placed on the surface of the inoculated media. the plates were incubated at (37 ºc for 24 hours). following incubation plates were examined in order to identify zones of on growth (halos around the fragments) characteristic for antibacterial activity. a c b d input voltage adjust input currentadjust voltage switch main switch light the touch screen for controllingthe spinning parameters like: flowrate, and rotation speed (a) (b) akram raheem jabur al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 8493(2017) 87 b. measuring antibacterial activity by the optical density method: the antibacterial activity of electrospun nanofibers membrane was tested by immobilizing nanofiber onto filters of a millipore, under vacuum filtration. a test water sample was prepared by inoculating (1*108 cells/ml) escherichia coli into (250 ml) of sterile normal saline water sample of (0.85 % nacl) in (100 ml) distilled water. water samples were then filtered through the membrane. after this step the optical density of the solution was measured by a uv spectrophotometer (uv1800 spectrophotometer, shimadzu) the number of bacteria was indirectly measured by optical density at (450 nm) in an ultraviolet (uv) –visible spectrometer and the antibacterial activity was calculated by the following equation: antibacterial activity=(a-b)/a×100% …(1) where a: the numbers of surviving cells in the control and b: the numbers of surviving cells in the test samples [27]. 3. results and discussion figure (4), shows the viscosities of electrospinning solutions with different (agno3) precursor concentration. it is clear shows viscosity of solution increased with increasing (agno3) concentration. as shown in figure (7) every (nylon) molecule layer binds with a silver nanoparticle because of the highest particle surface energy. as its discussed before, the formation of intermolecular interactions with chains in the solution from the (nylon 6) molecule chains on the surface of silver nanoparticles is responsible for the viscosity increase [28, 29]. 685 690 695 700 705 710 715 720 725 730 735 740 0 0.5 1 1.5 v is c o si ty (c p ) concentration of agno3 % fig. 4. effect the (agno3) on viscosity of (nylon 6). fig. 5. effect the (agno3) on electrical conductivity of (nylon 6). because of the presence of the (ag+ and no -3 ) ions the conductivity of the solution increase. figure (5) shows the increase in the solution conductivity with increasing (agno3) concentration. the surface tension of the electrospinning solution was increase due to the viscosity of solution increase. the effect of (agno3/nylon 6) on surface tension was showed in figure (6). fig. 6. effect the (agno3) on surface tension of (nylon 6). figure (7) shows that formic acid acts as a reducing agent in the reduction reaction of the (nylon 6) molecule chain solution. as soon as the silver nanoparticles are created, (nylon 6) molecules on the particle surface stabilize them in the nanosize and prevent them from more aggregating by decreasing their surface activity. nylon 6 molecules work as a matrix of electrospun nanofibers and a stabilizing agent of silver nanoparticles. akram raheem jabur al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 8493(2017) 88 fig. 7. silver nanoparticles formation and stabilization by the in situ generation mechanism [18]. figure (8-a) shows the (sem) image of (nylon 6) electrospun nanofibers mats, the nanofibers looks continues and smooth fibrous structure and homogeneous morphology, with an average diameter (139 nm) obtained from the histogram drawn from (sem) image analysis and calculated and shown in figure (8-b) for average fiber diameters and figure (8-c) for pore size. figure (8-a) shows (nylon 6) nanofibers fig. 8. (a) sem image of pure (nylon 6) nanofibers membrane, (b) diameter distribution and (c) pore size distribution. 0 2 4 6 8 10 12 14 16 n u m b e r o f fi b er fiber dimeter (nm) average fiber diameter =247 nm 0 2 4 6 8 10 12 14 f re q u en cy pore size (nm) average pore size =308 nm fig. 9. (a) sem image of (agno3 /nylon 6) nanofibers membrane, (b) diameter distribution and (c) pore size distribution. with resulted a smooth, free beads structures and homogeneous morphology. the (nylon 6) nanofibers maintained its morphology upon loading with (agno3), figure (9-a) with average nanofiber diameters (247 nm). fig. 10. edx spectrum result of (0.4% agno3/nylon 6). a b c a b b akram raheem jabur al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 8493(2017) 89 a high magnification (sem) image of (agno3/nylon 6) with the (edx) spectrum analysis of electrospun membrane suggests the chemical composition and show (ag (peak)) due to addition (agno3) reduced to (ag-nps). figure (10) edx spectra of (agno3/nylon 6) which confirm the existence of (ag-nps) and formed into fibers. our process to fabricate the (ag) nano purification (nylon fibers) to insure that the formed (ag-nps) will be inside the polymeric fibers and never at its surfaces to avoid removing its from fibers at application condition as a result of water or any fluid flow through for water purifications. microbiological study figure (11) shows the incubated petri plates of (e. coli) grown in presence of circular nanofiber mats after 24 hrs. from that figure (11), generation of clear zone surrounds circular mat contains silver-nanoparticles (agno3), where in the (nylon 6) nanofiber membranes these zones are absent. the creation of clear zones surrounds the nanofiber mat is an indicator for inhibition of bacteria colonies near the nanofiber mat edges. mainly, because of the existence of silver in the nanofiber mat, it may kill the microorganism that surrounds the mat which results in formation of clear circular zones. fig. 11. antimicrobial activities of (nylon 6) nanofibers against escherichia coli. (a) missing the inhibition zone in plain (nylon 6), (b) (1.2 %agno3), where the inhibition zone is visible in (nylon 6) embed (agnps(agno3)). quan shi et al.[19], shows that silver nanoparticles loaded nylon produced in one stage process can liberate a appropriate amount of silver to offer excellent antibacterial activity. antibacterial activity of nylon 6 loaded silver nanoparticles (agno3) showed an increase in the inhibition zone as the (agno3) increase due to increase (ag-nps) as the result of antibacterial activity test figure (12). fig. 12. effect of (agno3) on antibacterial activity of (nylon 6) by measuring an inhibition zone e.coli medium. antibacterial activity of (agno3/nylon 6) was also proven by optical density. optical density is measured by using a spectrophotometer. light scattering rises with the increase in cell number. when light is passed through bacterial cell suspension, light is scattered by the cells and transmission decays. at a particular wavelength, light optical density is proportional to the cell concentration of micro-organisms present in the suspension. this is a nondestructive method that is also very simple, rapid and accurate. both live and dead cells are, however, able to scatter light and, therefore, both are counted [26]. as show in (sem) image of the surface of nanofiber membrane and illustrate dendritic shape the cluster (live or dead) on surface of the membrane figure (13). which indicate that the filter can stop bacteria from passing through, while the formation of bacteria as a cluster on the surface of the filter and prevent it from penetrating through the nanofiber membrane. figure (14) shows the influence of the (agno3) concentration on antibacterial activity. the antibacterial activity the electrospun nanofiber mats increased by increasing the (agno3 wt.%) concentration, which approach to about (< 99% ± 0.5) for e. coli at concentrations of (1.2 wt.% agno3) in (nylon 6). an antibacterial properties has been found on nylon 6 nanofibers while the nylon nanofibers/ag nps showed excellent antibacterial activities against e. coli (gramnegative) and staphylococcus aureus (grampositive) bacteria as provided by m. montazer [30]. a b akram raheem jabur al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 8493(2017) 90 fig. 13. sem of membrane after exposing to bacteria where the bacteria cluster (a) on the membrane surface as a dendritic shape colony (b) and (c) shows how fiber captures the bacteria. fig. 14. antibacterial activities at different (agno3/nylon 6) membrane concentration. 4. conclusions this article portrays a simple way to deal with fabricated (ag nanoparticles inside nanopolymeric nylon fibers (agno3) by formic acid reduction), silver nano-particle loaded (nylon 6) nano fibers by means of a one-stage electrospinning process. this process includes silver nanoparticles formation and stabilization by the in situ generation mechanism where the solvent work as reducing agent and polymer matrix act as stabilizing agent. other than the electrospinning solution, this technique does not require extra reducing/protecting agents or (thermal/illumination) treatment. the in situ formation of nanoparticles and the stabilizing mechanism of (nylon 6) molecules result in a restricted size of silver nanoparticles and uniform scattering of silver nanoparticles in the nanofiber mat, as tested by (sem) and (edx). antibacterial measures demonstrate these nanofibers have more than (99.6%) antibacterial activity to e. coli. 5. references [1] j. theron, ja. walker, te. cloet, “nanotechnology and water treatment applications and emerging opportunities”, crit. rev. microbiol. vol. 34, (2008), pp: 43-69. 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[30] m. montazer, s. b. malekzadeh" electrospun antibacterial nylon nanofibers through in situ synthesis of nanosilver: preparation and characteristics", journal of polymer research, (2012), 19: 9980. doi:10.1007/s10965-012-9980-8. �� 1، ا���د�13�� ا������� ا������� ا���ارز� ا �م ر��� ��� �� ،93-84 )2017( 93 !'�ات ا��&��� �ا������� ��'�,�+ ا���"ه ��"��� ا��("دة ���)'� " ��&��ة ا$��"ف ا��"!� � ا� !" ��ن /(� ***��7 8�93 ���7 **��6 4�5 �3"س *��� �م ر��� أ 0@?<=1 ا0>;0.4.:19 ا /678 ھ1234 ا0/.اد ***،**،* akram.jabut@gmail.com *3abc0ا deوb<;0gا : ا��:�� أ90?ف اe?40. ا0/]?دة b;9/t0وz?ت j;/a . اt<0.ث اt0 d>.wb@0/9?ه <b9rs 1t;uة 3opد 1mn اkc7a lei 1>?=0 اj> 3a3=0 اb>iاض ?o=94^p_abط ja 0أ90?ف ا d8 1a.e?401 ا[b0ا cd> 1a.e?e 39اتc> e>د.e?4 . ن.ta?40٦ا h9ib<z j9>ر.b0ا l/m d8 l<z6 اذاp)٢٥٪ ( ، 6p اc<s?ر <tm.ل ا19t/a ccw b/90.c0 اbc0م . b<eات اu0]1 ا3aت 3v<2?zام 194up اbc0م اds?zbo;0/ اr90gف ا1a.e?40 <]?دة b@t0اta?e 69w.ن و:/jtp |9 ا0=.ا<k2?4<> c;uz 3ahp c <| زa?دة ) htو:lmr2 bp.p1، اc9n.<0 اds?zbo;0 وا0( اmt0 ds?zbo;0^.ل s zta.اص <tm.ل 1[b0ات اb<e 18?}~19 ا/i . �r2 ،19:.0.81 30را12 <.ر<<u<</01 ا=�g9?ف اr> �m8 ا0/?�2 و deوb<;0gا bo@/0ا �m8 �>3v<2وا �u?ء اk9ib<0 اb^4=0ي،brw ا90i?ف و m@6 ا7/0?<19 t0 . es?<40ء ا?u�t0 1a.e?4090?ف اgاbrw ن <=3ل?i �9m)١٣٩ b<>.e?e( ن.ta?4t0 6p 6w اc<s?ر ا19u�g ا1ab/90.c0 ا3u0 �m8 1@p?40رb9>3p zta ?op اb<e . d8 ?ab9<;c0ات ا1[b0 %) b<>.e?e( d8 ،)١.٢ ٢٤٧(اdu40 و <]?د b@t0ا69w {3 اab9<;c0? ا19e.0.u0 و 1ur4> �e?i اa �9cd<0?ل ?ف اb9w�p ?o0 .e?40ا0/?ء؛ وأ�?رت اc<sg?رات ا0/]?دة b;9/t0وz?ت أن أ90 )١٠ 6t> ( ?ab9<;ct0 190 ا0/]?د?=b0ا)و8_). ٪٩٩ zta1 وa.e?4090?ف اg19 اu3ام ا�v<219 اe?;>إ es?<40ھ�ه ا j9cp ،j0ذ ?obn.z c>ا.a .<]?دة b;9/t0وz?ت 2637 al-khwarizmi engineering journal,vol. 12, no. experimental and prediction using artificial neural network of bed porosity and solid holdup in viscous 3 department of chemical engineering (received abstract in the present investigation, bed poro determined for aqueous solutions of carbox a particles with low-density and diamete column. the effectiveness of gas velocity porosity bp and solid holdups εg were determ velocity", and "liquid viscosity". solid holdup decreases solid holdup with "low density particles density". levenberg-marquardt back propagation porosity and solid holdup. the expected values are in an excellent relationship with the experimental advanced model is high-fidelity and own a large capacity keywords: bed porosity, solid holdup, three phase, inverse fluidization 1. introduction a three phase (gas – liquid – fluidized bed (tpifb) is an operation where continuous liquid phase is introduced upper of the column in the opposite direction to the continuing flow of gas which from the bottom and the particles with low density expand down. applications of (tpifb) increased because, low pressure drop and heat transfer rates, low-level operating costs and higher efficiency contact between various phases [1-2]. three phase fluidized beds are used in petrochemical processing, chemical processing, biochemical processing, hydrogenat de-sulfurization of residual oil, facilitating catalytic and non-catalytic reactions [ to understand the phenomena of three phase fluidized bed, important parameters must described such as: bed pressure drop, minimum khwarizmi engineering journal,vol. 12, no. 3, p.p. 2637 (2016) experimental and prediction using artificial neural network of bed porosity and solid holdup in viscous 3-phase inverse fluidization amer a. abdulrahman department of chemical engineering/ university of technology email: ameraa1972@yahoo.com (received 2 february 2016; accepted 27 march 2016) orosity and solid holdup in viscous three-phase inverse arboxy methyl cellulose (cmc) system using polyethy eter (5 mm) in a (9.2 cm) inner diameter with height (2 velocity ug , liquid velocity ul, liquid viscosity µl, and were determined. the bed porosity increases with "increasing gas olid holdup decreases with increasing gas, liquid velocities and liquid viscosity. low density particles" shows a higher numerical quantity "than that in the beds back propagation of "artificial neural network (anns)" was xpected values are in an excellent relationship with the experimental own a large capacity to predict bed porosity and solid holdup. d porosity, solid holdup, three phase, inverse fluidization, anns. solid) inverse is an operation where introduced from the the column in the opposite direction to is introduced rticles with low density . applications of (tpifb) have been essure drop, higher mass operating costs between various three phase fluidized beds are used in petrochemical processing, chemical processing, biochemical processing, hydrogenation and hydro sulfurization of residual oil, facilitating catalytic reactions [3-4]. to understand the phenomena of three phase fluidized bed, important parameters must be such as: bed pressure drop, minimum fluidization velocity, bed p liquid holdup and solid holdup. the hydrodynamic characteristics of (tpifb) hav been studied by many researchers. (as gas phase and liquid (as solid phase) and bed height are im variables affecting the quality of fluidization the hydrodynamics of 3-phase fluidized bed was studied with different size as a continuous phase [6]. gas holdup and bed porosity increase increasing gas flow rate. fluidization velocity, physical properties are measured for three phase fluidized bed by using a perforated t distributor, different types of a non (pseudo plastic) liquids as a liquid phase, different types of gases as gas phase and activated carbon with different diameters as solid phase al-khwarizmi engineering journal (2016) experimental and prediction using artificial neural network of bed phase inverse fluidization e fluidized bed (tpifb) are ylene and polypropylene as m) inner diameter with height (200 cm) of vertical perspex , and particle density ρs on bed increasing gas velocity", "liquid increasing gas, liquid velocities and liquid viscosity. than that in the beds" with "high was utilized to predict the bed xpected values are in an excellent relationship with the experimental values, where the bed porosity and solid holdup. bed porosity, gas holdup, liquid holdup and solid holdup. the hydrodynamic characteristics of (tpifb) have studied by many researchers. fluid flow rate (as gas phase and liquid phase), particle density ed height are important variables affecting the quality of fluidization [5]. phase fluidized bed was studied with different sizes of particle and liquid ]. it was found that the oldup and bed porosity increase with asing gas flow rate. gas holdup, minimum fluidization velocity, physical properties of liquid are measured for three phase fluidized bed system by using a perforated teflon plate as a gas distributor, different types of a non-newtonian liquids as a liquid phase, different types of gases as gas phase and activated carbon with different diameters as solid phase [7]. amer a. abdulrahman al air was used as the gas phase, water phase, and low density particle (wood) as solid were employed to study the hydrodynamic characteristics of 3-phase fluidized bed phase two types of low density particles investigate the hydrodynamic characteristics of (tpifb) [9]. in newtonian (aqueous glycerol) and non-newtonian (aqueous solutions of carboxyl methyl cellulose) 3-pha fluidized bed, bed porosity and solid studied by using polyethylene and polypropylene particles of different diameters [10]. a feed forward neural network, multilayer perceptron was used for chemical engineering utilization which consists of hierarchical structure, input, output layer least one layer called (hidden) of processing units between them. artificial neural networks (anns) prepare correlation between input and output variables. the schematic of the mlp network with two hidden layers is as shown in there are a broad range of variables such as the expansion of the bed, gas, liquid holdups for gas-liquidsolid fluidized been used to generalize various between the data of non-linear parameters polyethylene hollow spheres, water and air are used experimentally in (tpifb) to find solute concentration and mass transfer coefficient. by using (anns), the data produced was used for providing models [12]. four different non newtonian liquids and four different polymeric solids in single and binary system inverse fluidized beds are used to study and develop empirical correlation for the bed expansion multilayer perceptron trained with propagation and levenberg algorithms has been used for the artificial neural network (ann) analysis because network training function that updates weight and bias values according to levenberg optimization. trainlm is often the fastest backpropagation algorithm in the toolbox, and is highly recommended as a first-choice supervised algorithm, although it does require mo than other" [13]. the aim of the present work, experimental data was use to develop a mathematic model to estimate solid holdup and bed porosity as µl, and ρs. 2. experimental work the planned laboratory design of experimental apparatus is exhibited in figure (2). al-khwarizmi engineering journal, vol. 12, no. 27 , water as liquid phase, and low density particle (wood) as solid study the hydrodynamic phase fluidized bed phase [8]. density particles were used to amic characteristics of (aqueous solutions of (aqueous solutions phase inverse solid holdup were using polyethylene and polypropylene ]. a feed forward neural network, multilayer used for chemical engineering of multilayer , output layers, and at least one layer called (hidden) of processing units artificial neural networks (anns) prepare correlation between input and output the schematic of the mlp network is as shown in figure (1). there are a broad range of variables such as liquid and solid solid fluidized bed has eneralize various relationships linear parameters [11]. hollow spheres, water and air are (tpifb) to find solute concentration and mass transfer coefficient. by data produced was used for four different nonliquids and four different polymeric ids in single and binary system inverse study and develop correlation for the bed expansion. a multilayer perceptron trained with back and levenberg -marquardt been used for the artificial neural "trainlm is a function that updates weight and bias values according to levenberg-marquardt optimization. trainlm is often the fastest backpropagation algorithm in the toolbox, and is choice supervised algorithm, although it does require more memory experimental data mathematic model to nd bed porosity as ug, ul, of experimental practical experiments vertical column made of perspex internal diameter and (2m) height introduced from the lower of the column via the gas distributor. the liquid phase was fed from the top of the column through a (3cm) liquid tank. the distributor of the evenly spaced holes, with diameter ( each, while the gas distributor spaced holes, with diameter individual phase holdup was pressure drop method based on the the particles height, pressure drop properties of the three phases are equally spaced (21.5cm) interval exterior wall of the part placed (5cm) from the water distributor on the top of the column. manometers are used to measure the pressure drop inside the column drop was measured with water veloci from fixed condition to supplied by air compressor capable of delivering about (5) bar. the air velocity rota meter ranging from (0 water was supplied by liquid reservoir with (0.1m3) in volume which pump with (5.4) m3/hr. an water velocity was measured with flow meter ranging from (0.010.06) m/ spheres were used as solid polyethylene and polyp average diameter of (5 mm). physical characteristics of the solid particles as solid phase. as a liquid phase three different carboxy methyl cellulose (cmc) were applied. operating conditions and of the liquid. a brookfield synchrolectric rotational viscometer was used to determine viscosity (µl) of "liquid phase "gas phase and" its properties (3). fig. 1. artificial neural network (anns) (multilayer perceptron) . khwarizmi engineering journal, vol. 12, no. 3, p.p. 2637 (2016) ractical experiments were carrying on in a made of perspex (0.092 m) ternal diameter and (2m) height. the air was the lower of the column via the . the liquid phase was fed from the top of the column through a (3cm) tube from the distributor of the liquid holds (48) evenly spaced holes, with diameter (2.5 mm) for each, while the gas distributor holds (26) evenly diameter of (2mm) for each. individual phase holdup was determined by static based on the cognition of pressure drop and the physical phases. six taps of pressure (21.5cm) interval on the part section; first tap was (5cm) from the water distributor on the top manometers are used to measure the pressure drop inside the column. the pressure drop was measured with water velocity ranging from fixed condition to fluidization. air was supplied by air compressor capable of delivering about (5) bar. the air velocity was measured with rota meter ranging from (0.05-0.75) m/s. supplied by liquid reservoir with was connected to water /hr. and (46m) h.max. the velocity was measured with flow meter ) m/s. two different solid as solid phase made of polyethylene and polypropylene beads with 5 mm). table (1) shows the of the solid particles as as a liquid phase pure water and methyl cellulose solutions . table (2) shows the and physical characteristics a brookfield synchrolectric rotational viscometer was used to determine the quid phase". air was used as a its properties are shown in table artificial neural network (anns) amer a. abdulrahman al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 2637 (2016) 28 1liquid column, 2liquid distributer, 3gas distributer 4 air compressor, 5 needle valve, 6liquid pump, 7gas flow meter, 8liquid flow meter, 9reservoir tank, 10vent line, 11u tube manometer. fig. 2. experimental apparatus. table 1, physical properties of particles as solid phase. table 2, properties of liquid phase. table 3, properties of gas phase. table 4, the limit of the input parameters in ann. ann is utilized to predict bed porosity and solid holdup under using matlab 7.10 software. the data of experiments can be divided into two sections, training and testing, and eventually trains the anns is built according to the specific data was trained to compute the achievement of the training results by using mean square error (mse) and the linear regressions (r2) [14, 15]. "��� = 1/�∑ �� − �������� " … (1) "�� = 1 − �∑ �������� ∑ ����� � " … (2) (t) act as a target value, where (y) act as an output value, and (n) act as a pattern. for present work, levenberg-marquardt backpropagation training algorithm is in use to train the network, for training artificial neural networks 270 of 384 data are in use and for testing aim 114 data are in use with log-sigmoid hidden neurons and linear output neurons. 3layers feed forward network are in use as the network, one for input layer, tow for hidden layer, and one for output layer. the input layer has 4 neurons (gas velocity, liquid velocity, density of the particles, and liquid viscosity), as in the case of hidden layers distributed 8 neutrons in the first one, four neutrons in the second layer and output layer has two neurons (bed porosity and solid holdup). the network was then trained to predict the bed porosity and solid holdup as outputs. table (4) presents the limit of the input parameters in ann. neurons are placed at the input layer in the feed forward networks towards output layer so that layers and transference from first layer to another one. the obtained data are change position from the beginning from input layer to the tow hidden layers and in the end sent to the output layer to be there to deal with the data for the final results and then sent out. figure (3) exhibit a feed forward ann for two hidden layers as utilized in present study. density (kg/m3) average diameter (mm) shape solid phase 875 5 spheres polypropylene 969 5 spheres polyethylene viscosity *103 (pa.s) density (kg/m3) liquid phase 0.97 1000 water 9.5 1001 water-cmc (0.1 wt. %) 35 1004 water-cmc (0.3 wt. %) 49.5 1006 water-cmc (0.5 wt. %) viscosity *105 (kg/m.sec) density (kg/m3 ) gas phase 1.6 1.19 air inputs range gas velocity (m/s) 0.05 – 0.75 liquid velocity (m/s) 0.01 – 0.06 liquid viscosity *103 (pa.s) 0.97 49.5 particles density (kg/m3) 875 969 amer a. abdulrahman al fig. 3. multilayer neural network 3. results & discussion 3.1 effect of superficial gas velocity (u in the present study, the variations of bed porosity (bp) with superficial gas velocity (u are shown in figures (4-5) using particle with liquid phase viscosity 9.5*10 49.5*10-3 pa.s respectively. the bed expansion and the total volume of fluidized bed increased with an increase in airflow rate, therefore the bed porosity also increased in inverse three phase fluidized bed. the accepted explanation is as follows the bubbles are broken by the large inertia of particles. typical examples of bed porosity can be seen in figures (6 al-khwarizmi engineering journal, vol. 12, no. 29 fig. 3. multilayer neural network. 3.1 effect of superficial gas velocity (ug) in the present study, the variations of bed ) with superficial gas velocity (ug) 5) using polyethylene particle with liquid phase viscosity 9.5*10-3 and pa.s respectively. the bed expansion and the total volume of fluidized bed increased therefore the bed porosity also increased in inverse three phase fluidized bed. the accepted explanation is as follows the bubbles are broken by the large inertia of particles. typical examples of bed porosity can be seen in figures (6-7) for polypropylene particles with liquid phase viscosity 9.5*10-3 and 35*10 and figures (8-9) for polyethylene and polypropylene particles with pure water as liquid phase respectively. the values of the bed porosity of light particles are smaller than those for heavy particles [3, 16, and 17]. the effects of ug on the figures (10-11) for polyethylene particles with viscosity of 9.5*10-3 and 49.5*10 phase respectively. the bed in the column expands when the ug increasing in the liquid and gas holdups which results decreasing in the these figures, the polypropylene holdup greater than that of the polyethylene. this is because the polypropylene than that of the polyethylene. this phenomenon is due to the beds of light particles which cannot expand easily in thifb b of the buoyant force a typical examples of solid holdup can be seen in figures (12-13) for polypropylene particle with liquid phase viscosity 9.5*10 respectively and figures (14 and polypropylene particles with pure water as liquid phase respectively [2,5,16,17]. khwarizmi engineering journal, vol. 12, no. 3, p.p. 2637 (2016) polypropylene particles with liquid phase and 35*10-3 pa.s respectively 9) for polyethylene and polypropylene particles with pure water as liquid phase respectively. the values of the bed porosity of light particles are smaller than those for heavy particles [3, 16, and 17]. on the εs are shown in 11) for polyethylene particles with and 49.5*10-3 pa.s of liquid phase respectively. the bed in the column increases, therefore liquid and gas holdups which results decreasing in the εs. as can be seen in these figures, the polypropylene owns solid than that of the polyethylene. this is because the polypropylene has density lower than that of the polyethylene. this phenomenon of light particles which cannot because of the influence of the buoyant force affecting the particles. typical examples of solid holdup can be seen in 13) for polypropylene particle with liquid phase viscosity 9.5*10-3 and 49.5*10-3 pa.s respectively and figures (14-15) for polyethylene and polypropylene particles with pure water as liquid phase respectively [2,5,16,17]. amer a. abdulrahman al fig. 4. influence of ug on bp particle: polyethylene; ρs = 969 [kg/m µl = 0.95 × 10-2 [pa.s]. fig. 5. influence of ug on bp. particle: polyethylene; ρs = 969 [kg/m µl = 4.95 × 10-2 [pa.s]. fig. 6. influence of ug on bp particle: polypropylene; ρs = 875 [kg/m µl = 0.95 × 10-2 [pa.s]. al-khwarizmi engineering journal, vol. 12, no. 30 fig. 7. influence of ug on bp = 969 [kg/m3]; particle: polypropylene; ρs = 875 [kg/m µl = 3.5 × 10-2 [pa.s]. fig. 8. influence of ug on bp = 969 [kg/m3]; particle: polyethylene; ρs = 969 [kg/m pure water; µl = 0.097 × 10-2 fig. 9. influence of ug on bp = 875 [kg/m3]; particle: polypropylene; ρs = 875 [kg/m . pure water; µl = 0.097 × 10-2 [pa.s] khwarizmi engineering journal, vol. 12, no. 3, p.p. 2637 (2016) bp = 875 [kg/m3] bp = 969 [kg/m3]; 2 [pa.s]. = 875 [kg/m3]; [pa.s]. amer a. abdulrahman al fig. 10. influence of ug on εg particle: polyethylene; ρs = 969 [kg/m µl = 0.95 × 10-2 [pa.s]. fig. 11. influence of ug on εg particle: polyethylene; ρs = 969 [kg/m µl = 4.95 × 10-2 [pa.s]. fig. 12. influence of ug on εg particle: polypropylene; ρs = 875 [kg/m µl = 0.95 × 10-2 [pa.s]. 3.2 effect of superficial liquid (ul) the effect of superficial liquid velocity (u on the bed porosity (bp) is represented in al-khwarizmi engineering journal, vol. 12, no. 31 fig. 13. influence of ug on εg = 969 [kg/m3]; particle: polypropylene; ρs = 875 [kg/m µl = 4.95 × 10-2 [pa.s]. fig. 14. influence of ug on εg = 969 [kg/m3]; particle: polyethylene; ρs = 969 [kg/m pure water; µl = 0.097 × 10-2 fig. 15. influence of ug on εg = 875 [kg/m3]; particle: polypropylene; ρs = 875 [kg/m pure water; µl = 0.097 × 10-2 [pa.s] iquid velocity the effect of superficial liquid velocity (ul) represented in figures (16 – 17) for polyethylene particle phase viscosity 35*10-3 respectively. as can be seen from these figures, the bed porosity increases with increasing superficial liquid velocity. khwarizmi engineering journal, vol. 12, no. 3, p.p. 2637 (2016) = 875 [kg/m3]; g = 969 [kg/m3]; 2 [pa.s]. = 875 [kg/m3]; [pa.s]. olyethylene particles with liquid and 49.5*10 -3 pa.s as can be seen from these figures, the bed porosity increases with increasing superficial liquid velocity. this can be due to the amer a. abdulrahman al fact that the gas holdup and liquid holdup increase gradually with increasing u gas velocity. this event could be due to the fact that the liquid phase flows moving down a the buoyance force act on the particles. trend is observed in the figures (18 beds of polypropylene particles with 35*10-3 and 49.5*10-3 pa.s of liquid phase respectively and figures (20-21) for polyethylene and polypropylene particles with pure water as liquid phase respectively. in the present study, figures (22 variation of solid holdup with superficial liquid fig. 16. influence of ul on bp particle: polyethylene; ρs = 969 [kg/m µl = 3.5 × 10-2 [pa.s]. fig. 17. influence of ul on bp particle: polyethylene; ρs = 969 [kg/m µl = 4.95 × 10-2 [pa.s]. al-khwarizmi engineering journal, vol. 12, no. 32 holdup and liquid holdup ul in a given . this event could be due to the fact that the liquid phase flows moving down against on the particles. a similar 8 19) for the with viscosity of pa.s of liquid phase ) for polyethylene olypropylene particles with pure water as – 23) give the uperficial liquid velocity for polyethylene particle phase viscosity 35*10-3 respectively. in these figure with increasing ul, as a results and gas holdups [2, 5]. the s seen in the bed of polypropylene particle with liquid phase viscosity 35*10 respectively in figures (24 27) for polyethylene and polypropylene particles with pure water as liquid phase respectively. fig. 18. influence of ul on bp = 969 [kg/m3]; particle: polypropylene; ρs = 875 [kg/m . µl = 3.5 × 10-2 [pa.s]. fig. 19. influence of ul on bp = 969 [kg/m3]; particle: polypropylene; ρs µl = 4.95 × 10-2 [pa.s]. khwarizmi engineering journal, vol. 12, no. 3, p.p. 2637 (2016) olyethylene particles with liquid 3 and 49.5*10-3 pa.s igures, the (εg) decreases as a results of increased liquid the same trend can be olypropylene particle with 35*10-3 and 49.5*10 -3 pa.s 4-25) and in figures (2627) for polyethylene and polypropylene particles with pure water as liquid phase respectively. on bp = 875 [kg/m3]; s = 875 [kg/m3]; amer a. abdulrahman al fig. 20. influence of ul on bp particle: polyethylene; ρs = 969 [kg/m pure water; µl = 0.097 × 10-2 [pa.s]. fig. 21. influence of ul on bp particle: polypropylene; ρs = 875 [kg/m pure water; µl = 0.097 × 10-2 [pa.s]. fig. 22. influence of ul on εg particle: polyethylene; ρs = 969 [kg/m µl = 3.5 × 10-2 [pa.s]. al-khwarizmi engineering journal, vol. 12, no. 33 fig. 23. influence of ul on ε = 969 [kg/m3]; particle: polyethylene; ρ . µl = 4.95 × 10-2 [pa.s]. fig. 24. influence of ul on εg = 875 [kg/m3]؛ particle: polypropylene; ρ µl = 3.5 × 10-2 [pa.s]. fig. 25. influence of ul on ε = 969 [kg/m3]; particle: polypropylene; ρ µl = 4.95 × 10-2 [pa.s]. khwarizmi engineering journal, vol. 12, no. 3, p.p. 2637 (2016) on εg particle: polyethylene; ρs = 969 [kg/m3]; on εg particle: polypropylene; ρs = 875 [kg/m3]; on εg particle: polypropylene; ρs = 875 [kg/m3]; amer a. abdulrahman al fig. 26. influence of ul on εg particle: polyethylene; ρs = 969 [kg/m3]; pure water; µl = 0.097 × 10-2 [pa.s]. 3.3. effect of liquid viscosity (µ typical plots of bed porosity against liquid viscosity are shown in figures polyethylene and polypropylene particles m/s for the gas velocity. as a result of the increase in drag force on the particles when increasing the viscosity of the liquid, gas velocity fig. 28 influence of µl on bp particle: polyethylene; ρs = 969 [kg/m ug = 0.35 m/s. fig. 29. influence of µl on bp particle: polypropylene; ρs = 875 [kg/m ug = 0.35 m/s. al-khwarizmi engineering journal, vol. 12, no. 34 particle: polyethylene; fig. 27. influence of ul on ε particle: polypropylene; ρs pure water; µl = 0.097 × 10 iscosity (µl) typical plots of bed porosity against liquid s (28 – 29) for olypropylene particles at 0.35 as a result of the increase in drag force on the particles when increasing the gas velocity and liquid velocity led to the increasing in the porosity of the bed for the inverse fluidize effects of liquid viscosity on the solid holdup in the bed are shown polyethylene and polypropylene particles. particles could be spread out the µl ; thus the εs decreases with increasing 18]. fig. 30. influence of µl on ε = 969 [kg/m3]; particle: polyethylene; ρs = 969 [kg/m ug = 0.35 m/s. fig. 31. influence of µl on εg = 875 [kg/m3]; particle: polypropylene; ρs ug = 0.35 m/s. khwarizmi engineering journal, vol. 12, no. 3, p.p. 2637 (2016) on εg s = 875 [kg/m3 ) 97 × 10-2 [pa.s]. led to the increasing in the porosity of the the inverse fluidized bed. ffects of liquid viscosity on the solid holdup in figures (30-31) for olypropylene particles. the spread out easily by increasing decreases with increasing µl [1, on εg = 969 [kg/m3]; on εg = 875 [kg/m3]; amer a. abdulrahman al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 2637 (2016) 35 3.4. artificial neural network model a three layer ann was used, a tangent sigmoid transfer function (tansig) at hidden layer and a linear transfer function (purelin) at output layer. feed forward levenbergmarquardt back propagation network was used. inside the input layer 4 neurons either in the first hidden layer there are 8 of neurons, as well as there are 4 neurons in the second hidden layer and output layer has two neurons. in the nn bed porosity model shown in figure (32 (a, b)), for training data set the r2 value is 0.990 and for testing data set is 0.981, where the mean square error (mse) values are 9.4610*10-5 and 1.9099*10-4 for training and testing data respectively. the ann solid holdup model is illustrated in figure (33 (a, b)), the r2 values are 0.999 and 0.982 for training and testing data sets respectively. mse values are 3.8676e*10-5 for training data set and 1.9099*10-4 for testing data set. figures (32 and 33) show the ann exhibit a close prediction supported on a high value of r2 and low value of mse. as a result, the developed nn bed porosity and solid holdup model successfully improve the prediction possibility of bed porosity and solid holdup value. fig. 32. the graphical output of the experimental fig. 33. the graphical output of the experimental bed porosity plotted versus neural network solid holdup plotted versus neural network predicted bed porosity. predicted solid holdup. . 4. conclusions the bed porosity and solid holdup of viscous three-phase inverse fluidized bed were experimentally investigated for gas velocity (from 0.05 to 0.75 m/s), liquid velocity (from 0.01 to 0.06 m/s) and liquid viscosity (from 0.97 *10-3 to 49.5*10-3 pa.s) : 1. solid holdup decreases (from 0.69 to 0.07) with increasing ug, ul and µl. 2. bp increases (0.31 to 0.93) with increasing ug, ul and µl. 3. anns were used to predict the bed porosity and solid holdup. the expected values are in an excellent relationship with the experimental values, where the advanced model is high-fidelity and own a large capacity to predict bed porosity and solid holdup. training data set for bed porosity model, the r2 value is 0.990 and for testing data set is 0.981, where the mean square error (mse) values are 9.4610*10-5 for training data set and 1.9099*10-4 for testing data. for solid holdup model, the r2 values are 0.999 and 0.982 for training and testing data sets respectively. mse values are 3.8676e*10-5 for training data set and 1.9099*10-4 for testing data sets. �� ا��� 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[14] sozen, a., and arcaklioglu, e., "exergy analysis of an ejector-absorption heat transformer using artificial neural network approach", journal of applied thermal engineering, vol.27, pp.481-491 (2007). [15] khalaj, g., yoozbashizadeh, h., khodabandeh, a., and nazar, a., "artificial neural network to predict the effect of heat treatments on vickers micro hardness of low-carbon nb micro alloyed steels", journal of neural comput & applic, vol.22, pp.879-888 (2013). [16] kim, s. d. and kang, y.," hydrodynamics, heat and mass transfer in inverse and circulating three-phase fluidized-bed reactors for waste water treatment", stud. surf. sci. and catal., 159: 103-108 (2006) . [17] kim, s. w., kim, h. t., song, p. s., kang, y. and kim, s. d., "liquid dispersion and gas-liquid mass transfer in three-phase inverse fluidized beds", can. j. chem. eng., 81: 621-625 (2003). [18] kang,y., cho,y. j., woo, k. j. and kim,s. d., "diagnosis of bubble distribution and mass transfer in pressurized bubble columns with viscous liquid medium", chem. eng. sci., 54, 4887-4893 (1999). �� ا��� ���� )2016( 2637، %$#� 3، ا�! د12 ��� ا���ارز�� ا��� ��� ا�������� 37 ���� ا�.��2 وا��#&�ى ا�#��� �����0� ا/%.����� ا�!-��� �ا�,�+ *��&� ام وا�&��' ا�&� ��9:9 ا�.�ر ا���جا�&���8 �!+�سأ* اج �4 ا�-�3 ��.�ر �� ا��� ���� ��� ا������ ا�������� � / ��� ا������ ا�� �و�� ameraa1972@yahoo.com ��: ا� ��� ا�����و ا��:%� �� �+*�ر ���� �)� '��ب ،ا�� $ ھ"ا ! ��; � �,�� $���2:�ام 787 � ا�*�ر ا�+��6ا�� 5 ����سأ2�اج !� ا�0+/ ا�* .� وا� ,��ى ا�,� ��<�2���@ ?و (cmc) ا��+ +�ز � = $ �+� ? a+�:� ?� ت� �� � �د �? ��ع !�) �+� ٥( �ر�*وf2 �ت ا��اط�dا��=�!ذو 2�و2+ ? وا� ��� ا7 + ? ا� ��@ (perspex) �+jدا �ا�* .� ���� � @+p ا��� �ت و>=�!� ا���;$، �6و�� ا���;$،و ا��oز ��@� !��� � ),��� )�). م )٢ ار�a(ع �5) م ٠.٠٩٢( و2.* � �+*�ر � �+*�ر. ا�* .� ���� �)tدي ا�p ز��دة ا���;$ و�6و�� ،ا���;$ ��@� ،ا��oز ��@� ز��دةوو�� ان . ا�0+/ وا� ,��ى ا�,� ا�� ا� ,��ى ا�,� � �+*�ر. ا���;$ و�6و�� ،ا���;$ ��@� ،ا��oز ��@�@�� ز��دة �.$ ا�0+/ �? أ@+p )��ن ا��=�!� ��:�d�6� �uaت�+ ا�0+/ وو�� ان ا� ,��ى ا�,� �ك ا��:�م و��. ا���� � ا��=�!� ذي ��d�6تا� � a � w����� �+*�ر ���� � ��� t ا�y*��@ � ا�� 0 � �x+ �� ا����� ��ر>�ارت2 ا�* .� وا� ,��ى ا�,� �����ا� . �وظ��ت ا�. ا�0+/ ��ة ��@ � و���[ ا���� @��� >�ن ا� *�ر ا�� �ذج ان ' \ ا� .���، ا�. � �5 � ��ز ا)�aق ! < p+@ t ���ا. al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 6, no. 2, pp 43-50 (2010) 355nm wavelength generation of nd:yag laser using olive oil aqeel s. fadhil* anwaar a. al-dergazly** ziad t. al-dahan** * ministry of oil/ state company for oil projects email: akeel_man_utd@yahoo.com ** department of laser and electronic optic/ college of engineering/ university of nahrain (received 27 april 2009; accepted 22 february 2010) abstract this project introduces a prospective material for photonic laser applications. the material is olive oil which is classified as organic compound, having a good nonlinear optical properties candidate to be used in photonic applications. a high purity sample of olive oil has been used. the theoretical calculation to generate third harmonic wave using olive oil has been determine using matlab program. thg (λ=355nm) intensity has been determined at two cases of sample thicknesses 1mm and 10mm. the minimum threshold incident intensity to obtain thg intensity are equal iω=7530 mw/cm2 at l=1mm and iω= 6220 mw/cm2 at l=10mm. the possibility of generation of third harmonic in olive oil inside the cuvette has been experimented using different powers (90-120) mw of cw nd:yag laser. the signal of third harmonic generation has been detected using uv-340 light meter. kewords: olive oil, third harmonic generation, thg intensity. 1. introduction the phenomenon of third harmonic generation (thg) is a well-known manifestation of the cubic optical nonlinearity of materials, χ(3). the efficiency of thg depends on the material nonlinearity, incident light (fundamental) intensity and the length of coherent interaction (sample thickness). high third-order nonlinearities are often reported for various materials, in particular organics [1]. olive oil an organic material consisted of two main groups of substances: saponifables and unsaponifables. a saponifables compound contains strong π-electron conjugation. this is a crucial factor in attaining high optical nonlinearities and, indeed olive oil have been considered for applications in which a high value of the nonlinear refractive index, n2 would be of advantage to obtain all-optical switching of optical signals at relatively low light intensities. also, olive oil can be used in biochemical application because of simplicity and compactness of the system. 2. theoretical results and discussion firstly, the transmission spectrum of olive oil is determined using uv-vis spectrophotometer as shown in figure 1. thg intensity can be determined theoretically using the following equation [2].               222)3( 2 2 244 2 3 2/ 2/sin3 il lk lk cn i o    ...(1) this equation shows thg parameters, which are represented by fundamental frequency ω, which are represented by fundamental frequency ω, interaction length or sample thickness l, third order nonlinear susceptibility χ(3) of the material which is determined experimentally using z-scan technique has a value of ≈ 10-12 m2/v2. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ akeel s. fadhil al-khwarizmi engineering journal, vol. 6, no. 2, pp 43-50 (2010) 44 fig. 1. olive oil transmission spectrum. iω represents the excitation intensity of laser beam. c and εo represents, the speed of light and vacuum permittivity. the wave vector at thg signal ∆k is determined from the following equation [2]: )( 6 3 33    nnkkk  ...(2) nω and n3ω respectively, the refractive index at fundamental and thg frequency, which is equal 1.46 and 1.4789 [3]. ω is the fundamental frequency at λ=1064nm, which equals 1.77×1015 hz. the wave vector ∆k equals 334.8mm-1. thg intensity is determined using the first equation at different input excitation intensity and by using computer program (matlab). two values of interaction length were used in calculations (l=1mm, l=10mm) as shown in figure 2. fig. 2. thg light intensity versus input excitation intensity for different interaction length. 0 0.5 1 1.5 2 2.5 3 3.5 x 10 5 0 500 1000 1500 2000 2500 3000 3500 4000 4500 excitation intensity(mw/cm2) th g in te ns ity (m w /c m 2 ) l=1mm l=10mm thg approximatly = 0 this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ akeel s. fadhil al-khwarizmi engineering journal, vol. 6, no. 2, pp 43-50 (2010) ٤٥ from figure 2, the variation in thg intensity is proportional to the square of excitation intensity; the variation is low at (0.0318×105 – 0.122×105 mw/cm2) while after 0.138×105 mw/cm2 for l=1mm and 0.18×105 mw/cm2 for l=10mm the variation increases rapidly until to reach the maximum value at 3.25×105 excitation intensity in this figure. the interaction length l affects the thg intensity. the threshold intensity ith to obtained thg were found from figure 2 by changing the incident powers in two cases of interaction length, l=1mm and l=10mm as shown in tables 1 & 2 respectively where the spot area a=πd2/4, d represents the spot diameter was changed between d=0.2mm and 2mm. then, ith=4p/πd2 [2], p is the incident power. table1, threshold values of thg intensities at l=1mm. power (mw) ith (mw/cm2) i3ω (mw/cm) spot area (mm2) 80 6220 0.01 1.286 100 6310 0.01 1.583 120 13600 0.1 0.882 140 13720 0.1 1.02 table2, threshold values of thg intensities at l=10mm. power (mw) ith (mw/cm2) i3ω (mw/cm2) spot area (mm2) 80 7570 0.1 1.0568 100 7530 0.1 1.327 120 7170 0.1 1.628 140 15860 1 0.882 the maximum values of thg intensities were observed in the case of phase-matching or noncollinear. phase-matching can be obtained when the wave vector δkl=0 by changing the thickness of sample. efficient thg is difficult to achieve in the olive oil because the wave vector δk≠0 and n3ω>nω [2]. in the case of different thickness of sample l, phase-matched thg intensity can be achieved as shown in figures 3. figures 3 shows the phase-matching and phase mis-matching of thg intensity, which is determined at four values of spot diameter of the fundamental beam d (0.1, 0.12, 0.14, 0.16) mm and for different values of sample thickness l from 10-100 μm in step of 1. fig.3. phase-matched thg intensity at 80mw input power. as a result, phase-matched thg intensity was obtained at the values of sample thickness (10, 28, 46, 66) μm. phase mis-matched thg intensity was obtained at the values of sample thickness (18, 37, 56, 75, 93) μm. the phase mismatch occurs periodically every 18μm (i.e. the coherent length lc equal 18μm). also, the variation of the thg intensity is proportional to the value of spot diameter into phase matching and mis-matching. for the value of spot diameter (d=0.1mm), thg intensity has become at maximum value, while at the value of spot diameter (d=0.16) it has become at minimum value. the reason of this effect is that the incident intensity is increased by reducing the spot diameter. so, for small spot diameter the intensity of incident laser beam becomes very high and thg intensity is increased by increase the intensity of excitation beam. 3. experimental thg intensity is measured experimentally using a simple set-up in laboratory as shown in figure 5. the set-up was consisted of the following components: 1nd:yag cw infrared laser (λ=1064nm). 2the sample, which represented the solution of olive oil filled in 1mm quartz cuvette. 3uv-light meter, which is shown in the figure 5. figure 4 shows the block-diagram of thg measurements: 10 20 30 40 50 60 70 80 90 100 0 500 1000 1500 sample thickness(m) t h g i n te n s it y ( m w /c m 2 ) d=0.1mm d=0.12mm d=0.14mm d=0.16mm this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ akeel s. fadhil al-khwarizmi engineering journal, vol. 6, no. 2, pp 43-50 (2010) 46 fig. 4. block-diagram of thg measurements. fig. 5. set-up of thg experiment. assuming a plane wave and non-depleting fundamental power, the thg output power was measured for different incident angles in the range from -30° to 30° increments of 5°step. the measurements of intensity based on two values of sample thickness 1mm and 10mm. the incident angle of fundamental beam θ was changed by tilt the sample forward to the left of the optical axis to make a positive angle and backward to the right of the optical axis to make a negative angle. bevelsquare was used to measure the incident angle. thg output signal intensity was measured with respect to the reference value when the quartz cuvette is blank. at the reference, very low uv radiation was detected, which represented the rayleigh-scattering or stimulated raman scattering. this value is regarded in measurements. the efficient values of thg output signal intensity was found as shown in figures 6 to 9: fig. 6. thg output intensity excited at 90mw input power versus incident angle for l=1mm. fig. 7. thg output intensity excited at 100mw input power versus incident angle for l=1mm fig. 8. thg output intensity excited at 120mw input power versus incident angle for l=1mm. nd:yag laser sampledetector -30 -20 -10 0 10 20 30 220 240 260 280 300 320 340 360 380 400 tilt angle(deg.) t h g i n te n s it y (m w /c m 2 ) data 5th degree -30 -20 -10 0 10 20 30 100 150 200 250 300 350 400 450 incident angle(deg.) t h g i n te n s it y (m w /c m 2 ) data 7th degree -30 -20 -10 0 10 20 30 20 40 60 80 100 120 140 160 180 incident angle(deg.) t h g i n te n s it y (m w /c m 2 ) data 7th degree this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ akeel s. fadhil al-khwarizmi engineering journal, vol. 6, no. 2, pp 43-50 (2010) 47 fig. 9. thg output intensity excited at 110mw input power versus incident angle for l=1mm. the result shows different values of thg intensity at each input power due the change in the incident angle of fundamental beam. the reason of change the incident angle of the fundamental beam is to obtain on efficient thg intensity. the change in the incident angle of fundamental beam was induced change in the reorientation of the olive oil molecules, which induced change in refractive index for l=10mm, thg output signal intensity was measured with respect to the reference value. very low uv radiation of scattering was detected at the reference (when the cuvette is blank). the efficient thg output signal intensity was found as shown in figures10 to 13: fig. 10. thg output intensity excited at 90mw input power versus incident angle for l=10mm. fig. 11. thg output intensity excited at 100mw input power versus incident angle for l=10mm. fig. 12. thg output intensity excited at 110mw input power versus incident angle for l=10mm. fig. 13.thg output intensity excited at 120mw input power versus incident angle for l=10mm. -30 -20 -10 0 10 20 30 0 50 100 150 200 250 incident angle(deg.) t h g i n te n s it y (m w /c m 2 ) data shape-preserving -30 -20 -10 0 10 20 30 0 50 100 150 200 250 incident angle(deg.) t h g i n te n s it y (m w /c m 2 ) data 8th degree -30 -20 -10 0 10 20 30 0 50 100 150 200 250 incident angle(deg.) t h g i n te n s it y (m w /c m 2 ) data 5th degree -30 -20 -10 0 10 20 30 0 50 100 150 200 250 incident angle(deg.) t h g i n te n s it y (m w /c m 2 ) data shape-preserving -30 -20 -10 0 10 20 30 120 140 160 180 200 220 240 260 280 incident angle(deg.) t h g i n te n s it y (m w /c m 2 ) data 7th degree this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ akeel s. fadhil al-khwarizmi engineering journal, vol. 6, no. 2, pp 43-50 (2010) 48 the results show different values of thg intensity for each input power due to the change in the incident angle of fundamental beam. also, the efficient thg intensity was approximately obtained at incident angle in rang from -15° to 15° because no signal will be detected at the incident angles -20° and 20°. these angles represent the best angles of thg signal because of high reabsorption of thg intensity occurred at these angles. the experimental results were compared with theoretical results as shown in figure 14. fig. 14. theoretical and experimental values of thg intensity. from figure 14, the experimental values of thg intensity are in good agreement with theoretical values. this case was obtained when the excitation beam (fundamental beam) was incidence in the medium. fig. 15. efficiency of conversion the fundamental beam into thg for l=1mm & l=10mm. the efficiency of the conversion of the fundamental beam into thg beam is determined experimentally using the following formula at l=1mm & l=10 mm for different incident powers as shown in figure 15: ....(3) 4. conclusions we have reported on efficient third harmonic generation in self-focusing in olive oil solution. we have theoretically determined the threshold intensity to obtained thg intensity in olive oil for two cases of sample thicknesses. for 1mm the threshold intensity to obtained thg equal iω=7530 mw/cm2 and for 10mm the threshold intensity to obtained thg equal iω= 6220 mw/cm2. also, the coherence length of olive oil is equal to 18μm, which is obtained from the simulation results, when third order nonlinear susceptibility equals ~10-12 m2/v2 for different input powers. thg intensity is changing with the change in the incident angles. the best incident angles are equal -10, 0, +10 degree for l=1mm and +5, 0 degree for l=10mm to obtained the maximum generation. notation a spot area of laser beam c light speed in vacuum d spot diameter of laser beam iω, i(0) incidence intensity i3ω third harmonic generation intensity ith threshold incident intensity to obtain thg kω wave number of fundamental beam k3ω wave number of thg beam ∆k wave vector phase mis-match l sample length n total refractive index nω refractive index at frequency ω n3ω refractive index at frequency 3ω p incident power )0( )(3   i li conversionofefficiency  7 7.5 8 8.5 9 9.5 10 10.5 11 x 10 4 0 100 200 300 400 500 600 incident intensity(mw/cm2) t h g i n te n s it y (m w /c m 2 ) theoretical l=1mm theoretical l=10mm experimental l=1mm experimental l=10mm 90 95 100 105 110 115 120 125 130 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.6 incident power(mw) e ff ic ie n c y o f t h g % l=10mm l=1mm this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ akeel s. fadhil al-khwarizmi engineering journal, vol. 6, no. 2, pp 43-50 (2010) 49 greek letters εo vacuum permittivity λ wavelength ω angular frequency 5. references [1]m. samoc, a. samoc, b. luther-daives, "third harmonic autocorrelation and wave mixing in poly(p-phenylenevinylene", optical society of america: optics express, vol. 11, no. 15, 1787-1792, (2003). [2]m. g. pabadopouls, a. j. sadlej and j. leszcynski, "nonlinear optical properties of matter", springer, netherlands, (2006). [3]aqeel salah fadhil," study of nonlinear optical properties of olive oil", m.sc. thesis, nahrain university, (2009). this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ )2010( 50-43 ، صفحة2، العدد 6المجلد مجلة الخوارزمي الھندسیة عقیل صالح فاضل 50 یاك باستخدام زیت الزیتون-نانومتر للیزر الندیمیوم ٣٥٥تولید التوافق الثالث **زیاد طارق الدھان** أنوار عبد الستارالدركزلي* عقیل صالح فاضل ارة النفطوز/ شركة المشاریع النفطیة * akeel_man_utd@yahoo: البرید االلكتروني جامعة النھرین/ كلیة الھندسة /قسم ھندسة اللیزر وااللكترونیات البصریة ** :الخالصة ة زر الفوتونی ات اللی وي یم . یقدم ھذا المشروع مادة جدیدة مقترحة لتطبیق ب عض نیفھ كمرك ن تص ذي یمك ون ال ت الزیت ي زی ادة ھ ذه الم فات ھ ك مواص تل ون . الخطیة جیدة تمكنھ من استخدامھ في التطبیقات الفوتونیة ث , استخدمت عینة ذو نقاوة عالیة من زیت الزیت ق الثال د التواف ة لتولی ابات النظری اد الحس م ایج ت م و ١نانومتر نظریا على سمكین للعینة ٣٥٥حیث تم ایجاد شدة الطاقة للتولید التوافقي الثالث . باستخدام زیت الزیتون باستخدام برنامج الماتالب م ١٠م ل . م اق .مم١٠لسمك العینة ٢سم/ملي واط ٦٢٢٠مم و تساوي ١لسمك العینة ٢سم/ملي واط ٧٣٥٠قیمة لشدة الطاقة حتى یحصل التوافق الثالث تساوي تخدام تم تو. مم١٠مم و١تم ایجاد شدة الطاقة للتولید التوافقي الثالث على سمكین للمادة , عملیا ة باس لید التوافق الثالث في زیت الزیتون داخل حاویة زجاجی .ملي واط) ١٣٠-٩٠(یاك ذو الموجة المستمرة وبمختلف الطاقات -لیزر الندیمیوم this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 6, no. 2, pp 11-20 (2010) study of nox emissions of s.i. engine fueled with different kinds of hydrocarbon fuels and hydrogen miqdam t. chaichan* qahtan a. abass** department of mechanical engineering/ university of technolog * email: miqdam_tc@hotmail.com ** email: qahtan_alnakeen@yahoo.com (received 8 october 2009; accepted 17 february 2010) abstract liquefied petroleum gas (lpg), natural gas (ng) and hydrogen were used to operate spark ignition internal combustion engine ricardo e6, to compare nox emissions emitted from the engine, with that emitted from engine fueled with gasoline as a fuel. the study was done when engine operated at hucr for gasoline, compared with its operation at hucr for each fuel. compression ratio, equivalence ratio and spark timing were studied at constant speed 25rps. the results appeared that nox concentrations will be at maximum value in the lean side near the stoichiometric ratio, and reduced with moving away from this ratio for mixture at both sides, these concentrations were at its highest value when hydrogen used at cr=8:1, and got near to each other for the three hydrocarbon fuels used in the study, when the engine operated at hucr for each fuel, but still hydrogen had maximum value, the main variable affect these concentrations was spark timing. keywords: liquefied petroleum gas, natural gas, hydrogen, compression ratio, nox emissions, spark ignition engines. 1. introduction thermal nox formed by the stabilization of atmospheric nitrogen in oxidizing atmospheres at a high flame temperature exceeding 1573k or 1300 °c. thermal nox is generally produced during the combustion of both gases and fuel oils [1]. when the combustion is under fuel-lean conditions (with less air) and there is a rise in temperature, this will lead to an increase of nox emissions due to increased oxygen radicals forming in the combustion process. however, when the combustion is under fuel-rich condition (with excess fuel) the oxidation reaction will involve the oh and h radicals [2]. high activation energies are required for the dissociation of oxygen molecules and the disengagement of the triple bond of nitrogen. this phenomenon causes the formation of thermal nox to be largely dependent on the temperature, the degree of air to fuel mixing, the concentration of oxygen and nitrogen in the flame and duration of reaction occurred [3]. the environmental problems caused by nox are now worldwide issues due to the seriousness of ozone reactivity and the amount of formation of smog. nox combines with water vapor in clouds to produce acid rain which pollutes clean water sources and corrodes metals used in our daily life. acid rain also harms the growth of organisms in the lake and disturbs the balance of the ecosystem both on land and at sea. apart from that, acidified soil is the also the result of acid rain and it causes damage to the root system of trees, disabling the nutrient absorption process and disrupting the natural process of photosynthesis[4]. when nox react chemically with other atmospheric gaseous compounds such as “volatile organic compounds” (vocs) under the sunlight, it will form smog. smog is forefront to our environmental concerns as it reduces the visibility of surroundings and poses a health hazard to this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ miqdam t. chaichan al-khwarizmi engineering journal, vol. 6, no. 2, pp 11-20 (2010) 12 humans which includes irritation of eyes, respiratory and cardiovascular problems such as asthma and headaches [5]. there are several factors which affect the formation of nox in the engine and they are listed below: the air-fuel ratio: plays a major role in determining the amount of emission of nox as oxides of nitrogen are formed by the reaction of nitrogen in the fuel with oxygen in the combustion air. when the air to fuel ratio is greater than one which indicates that the combustion is in the lean condition, the fuel mixture has considerably less amount of fuel and excess amount of air. engines designed for lean burning can achieve higher compression ratios and hence produce better performance. however, it will generate high amount of nox due to the excess oxygen present in the air [6]. combustion temperature: is also one of the primary factors that influence the formation of nox. the formation of nox is directly proportional to the peak combustion temperature, with higher temperatures producing higher nox emissions from the exhaust [7]. the firing and quenching rates also influence the rate of nox formation where a high firing rate is associated with the higher peak temperatures and thus increases the nox emission. on the other hand, high rates of thermal quenching result in lower peak temperatures and contribute to the reduction of nox emission [8]. engine parameters such as load and speed of engine also influence the nox emissions from the exhaust. when the engine is running under lean conditions, it emits less nox. however the nitric oxide (no) emissions will consequently increase as the engine load increases. the effect of load becomes less significant when the engine is running close to stoichiometric air to fuel ratio. on the other hand, engine speed may increase or decrease the no emissions as higher engine speed increases the burned gas mass fraction and thus offsets the peak temperature, depending on the exact engine conditions [9]. the term “alternative gaseous fuels” relates to a wide range of fuels that are in the gaseous state at ambient conditions, whether when used on their own or as components of mixtures with other fuels. they have distinct superior merits to those of conventional liquid fuels in applications whether those for spark ignition or compression ignition engines. additionally, most of these fuels can produce more favorable exhaust emission characteristics that can meet better the ever increasingly stringent emission regulations combined with enhanced power production efficiency and improved engine operational life [10]. the most common of the alternative fuels is natural gas that is usually made available after processing as “pipeline processed natural gas”. it is supplied for engine applications normally as compressed natural gas, (cng), or occasionally in its cryogenic liquid form, (lng). the composition of the gas in its natural untreated state varies widely depending on its source, treatment and local conditions. however, after it’s processing when destined for transport to its ultimate consumption points its composition becomes less widely variable and made up mostly of methane. accordingly, much of the work and information available relating to natural gas as an engine fuel consider methane to be an adequate representation of the whole fuel [11]. another common source of gaseous fuels involves the higher molecular weight components of natural gas in the form of liquefied petroleum gases (lpg), which can be liquefied under pressure at ambient temperature. usually, the main component of these fuel gases is n-propane. on this basis, often engine performance with pure or even commercial propane is considered to be represented adequately by engine operation with lpg gas mixtures [12]. hydrogen as an engine fuel is well recognized to have unique and excellent combustion characteristics while producing effectively negligible exhaust emissions, except for nox. moreover, the addition of h2 to relatively slow burning fuels such as ch4 was shown to accelerate the flame propagation rates and extend the lean operational limits [13]. there is every indication that the use of hydrogen whether on its own or in combination with other fuels will be an attractive stage in the road towards achieving the “hydrogen economy”. this is perhaps despite the well recognized limitations associated with its engine application arising from the need to develop improved methods for its economic manufacture, ease of availability, storage and transport while ensuring the safety of its handling [14]. the aim of this work is studying the influence of some spark ignition engine parameters (like compression ratio, spark timing equivalence ratio) on resulted nox emissions, when this engine was fueled with different gaseous fuels, and compare these emitted emissions with ones resulted from engine working with gasoline. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ miqdam t. chaichan al-khwarizmi engineering journal, vol. 6, no. 2, pp 11-20 (2010) 13 2. expermintal technique the investigation were carried out on single cylinder ,4-stroke spark ignition ricardo e6 engine with variable compression ratio, spark timing and equivalence ratio, operated with gasoline, ng, lpg and hydrogen. gasoline delivery system consists of the following parts, main fuel tank 6 liters capacity, supplementary fuel tank 1 liter capacity and gasoline carburetor. lpg delivery system consists of fuel tank (80 kg of lpg), fuel filter, solenoid valve, gaseous fuel flow rate measuring device (orifice plate), damping tank, gas carburetor. hydrogen and ng supplying system was consist of gas cylinder, pressure regulator, chocked nozzles system as gas flow rate measuring device and as flame trap. alcock air flow meter was used to measure air flow rate, speed was measured by tachometer. all the measuring devices were calibrated several times during the work. the following instruments were used for the analysis of the emissions:  a magnetic oxygen analyzer for o2.  a chemiluminescence analyzer for no and no2. the engine was operated with gasoline; ng, lpg and pure hydrogen. in practice, much of the gaseous fuels available are usually mixtures of various fuels and some diluents, constituents that can vary widely in nature and concentration, depending on the type of fuel and its origin. in this work the gasoline used was iraqi dora refinery production with octane no. 86, the lpg fuel produced from al taji gas company; consist of ethane 0.8%, 18.47 isobutane, 47.8% propane and 32.45% butane. ng used was produced from iraqi northern gas company; consist of 84.23% methane, 13.21% ethane, 2.15% propane, 0.15% isobutane, 0.17% n. butane and 0.03% pentane. hydrogen produced from al mansur company with 99.99% purity. the very wide diversity in the composition of the gaseous fuels commonly available and their equally wide variety of their associated physical, chemical and combustion characteristics make the prediction and optimization of their combustion behavior in engines a more formidable task compared to conventional liquid fuels. continued research is needed to provide more light on their suitability as engine fuels and understand better the roles of the many factors that control their behavior so as to achieve in practice the many potential superior benefits associated with their applications as engine fuels. 3. discussion 3.1. compression ratio effect fig.1. compression ratio effect on nox concentration for wide range of equivalence ratios, for gasoline fuel. fig. (1) shows the nox resulted from gasoline engine for wide range of equivalence ratios and for several compression ratios, nox increased in the lean side with the increase of cr, for equivalence ratio less than (ø =0.9), this was appeared by increased exhaust gas temperatures for these ratios, which increased from 525 to 585oc. these concentrations reduced in the rich side for equivalence ratios more than (ø =1.1), because of the increase in maximum cycle temperature with cr increased. for equivalence ratios (ø =0.9-1.1) where the engine produced the maximum brake power, nox concentrations reduced with increased cr, because of interference of new parameter, it was the optimum spark ignition timing, with cr increased the mixture temperature increased inside combustion chamber, improving the burning and increasing the flame propagation velocity, causing the optimum spark timing to retard, to insure knock preventing. this operation reduces the nox formation required time; this phenomenon will this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ miqdam t. chaichan al-khwarizmi engineering journal, vol. 6, no. 2, pp 11-20 (2010) 14 appear in spark timing study clearly. nox concentrations increased at cr=8.5:1 for these equivalence ratios range, because the cr effect prevailed ost effect and because of knock occurrence. fig.2, compression ratio effect on nox concentration for wide range of equivalence ratios, for lpg fuel. the same conditions appear in fig. (2) for lpg used as an engine fuel, with some extend in the lean equivalence ratios, making the cr effect obvious in this side for equivalence ratios less than ø =0.75. ng used as fuel in fig. (3), to show cr effect on nox emitted by the engine, from the previous figures, the maximum value for nox concentrations come within ø =0.95-0.98 for ng, and for lpg between ø =0.92 0.95, and for gasoline at ø =0.9 0.93. the working at lean equivalence ratios less than ø =0.8 gives accepted concentrations for usa and europe emission limitations for 1996, with insured condition that burning failure will not happen. fig.3. compression ratio effect on nox concentration for wide range of equivalence ratios, for ng fuel. fig.4. compression ratio effect on nox concentration for wide range of equivalence ratios, for hydrogen fuel. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ miqdam t. chaichan al-khwarizmi engineering journal, vol. 6, no. 2, pp 11-20 (2010) 15 fig. 5. comparison between nox concentration for wide range of equivalence ratios for the four fuels used in the study at cr= 8:1, which is the hucr for gasoline. fig. (4) represents nox emitted from the engine when fueled with hydrogen, hydrogen engine gave high nox concentrations for equivalence ratios between ø =0.6-0.8. in particular hydrogen engine emitted high nox concentrations compared with other fuels and this clear in fig. (5), which compares between the four used fuels at cr=8:1, lpg is the second higher nox levels and gasoline the third one. hydrogen has high flame propagation speed, this makes its burning very fast, causing high temperature and pressure inside the combustion chamber, with available formation time, and the required conditions for nox formation were fulfilled. in the other hand, lpg has high heating value on mass basis, its flame speed a little more than gasoline, for these reasons it became the second. ng has a property of slow flame speed, and its heating value on mass basis is less than lpg and gasoline, for these reasons it became the last. fig.6. comparison between nox concentrations for wide range of equivalence ratios for the four fuels used in the study when the engine worked at each fuel hucr. fig.7. maximum nox concentrations resulted with compression ratios studied for each fuel. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ miqdam t. chaichan al-khwarizmi engineering journal, vol. 6, no. 2, pp 11-20 (2010) 16 fig. (6) compares nox concentrations emitted by the four fuels when each one of them fueled the engine at its hucr. hydrogen still precedes the others, especially in lean side, because of its high burning velocity. lpg still the second indicating its high heating value, and ng still the last demonstrating its low burning speed and low heating value on volume basis. the figure shows that nox concentrations approached one another for the hydrocarbon fuels, when the engine worked at hucr for each fuel, while hydrogen’s values moved away from them. this can be reached by referring to fig. (7), which represents the relation between cr and maximum nox concentrations for all fuels used in this work. 3.2. equivalence ratio effect the figs. (1 to 6) show that nox concentrations very low in extremely lean and in highly rich equivalence ratios, these concentrations increased highly in the lean side to reach its maximum value near the stoichiometric equivalence ratio from the lean side, after this value nox concentrations reduced with mixture enrichment. in lean burn engines, increasing the air to fuel ratio decreases the nox emissions. extra air dilutes the combustion gases, thus lowering peak flame temperature and reducing thermal nox formation. oxygen availability and high burning temperature resulted from burning most of the fuel, also the time available for formation, all these conditions cause the nox concentration to increase in the lean limit (ø =0.7-0.95). nox concentration reduced in the rich side with cr increased because of lack of oxygen needed for reactions, the high increase in burning temperatures, low nox formation and dissociation equilibrium, all can be considered additional reasons of low nox concentrations, where dissociation reactions freeze in the expansion stroke. lowering the air-to-fuel ratio in rich burn engines limits oxygen availability in the cylinder, thus decreasing nox emissions. hydrogen had extremely lean equivalence ratios less than ø =0.6, which gave very low nox concentrations, these ratios can't be reached by any other known fuel. although hydrogen has low heating value on volume basis, resulted nox in lean side higher than ø =0,65, was high compared with the other tested fuels, which had higher heating values than hydrogen, but hydrogen flame velocity proceeds flame velocities for other fuels in many steps ( for hydrogen flame speed is between 2.65 – 3.4 m/s, for gasoline 0.34 m/s, for lpg 0.42 m/s and for ng 0.29 m/s), its burning and propagation increase combustion chamber pressure and temperature to very high levels, which can't be reached by other fuels, and it will increase the nox concentrations to these undesirable degrees. hydrogen engine operation at equivalence ratios less than ø =0.6 emitted very low nox concentrations, here the effect of little fuel quantity appeared, although of the high flame velocity. a fuel lean mixtures act as heat sinks lowers cylinder temperature and further reduces nox formation. 3.3. spark ignition effect fig.8. studying spark timing effect on nox concentrations for specific lean equivalence ratio, for each fuel used in the study, when the engine worked at each fuel hucr. spark ignition effect on nox concentrations for very lean equivalence ratios in exhaust gas was studied at hucr and 1500 rpm engine speed, for four chosen lean equivalence ratios for each fuel, as fig. (8) represents, for gasoline ø =0.83 was chosen, ø =0.75 for lpg, ø =0.75 for ng and ø =0.7 for hydrogen. from the figure there was high reduction in nox concentrations for all ratios, with retarding spark timing. nox concentrations reduced about 42% when spark this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ miqdam t. chaichan al-khwarizmi engineering journal, vol. 6, no. 2, pp 11-20 (2010) 17 timing was retarded 10obtdc for gasoline fuel. for lpg the concentrations reduced 37% with retarding spark timing 10obtdc from the optimum spark timing. for ng with the same condition nox concentrations reduced 79%, for hydrogen reduced about 66% with spark timing retarded 10obtdc. the spark timing effect appeared clearly for equivalence ratios near stoichiometric (as fig. (9) shows), gasoline nox concentrations reduced 42% when spark timing retarded 10obtdc at equivalence ratio ø =0.92, for lpg, nox concentrations reduced about 42% at ø =0.95 (near this ratio formed the maximum concentrations) for the same conditions, with ng as fuel, nox concentrations reduced 70%, and for hydrogen the reduction was 50%. fig.9. studying spark timing effect on nox concentrations for specific near stoichiometric equivalence ratio, for each fuel used in the study, when the engine worked at each fuel hucr. the high reduction in nox concentrations for ng due to its low burning velocity, which make spark timing effect on maximum temperature inside the combustion chamber obvious, the spark timing for ng always advanced compared with the other fuels. ignition or spark timing retard lowers nox emissions by moving the ignition event to later in the power stroke. because the combustion chamber volume is not at its minimum, the peak flame temperature will be reduced, thus reducing thermal nox formation. ignition timing retard is applicable to all engines. it is implemented in spark ignition engines by changing the timing of the spark. retarding spark timing effect on nox concentration was very limited at rich equivalence ratios (as fig (10) shows), when spark timing retarded 10obtdc gasoline nox concentrations reduced only 12% at ø =1.3, at the same equivalence ratio but for lpg the concentrations reduced 15% when spark timing retarded 10obtdc, when ng was used as a fuel at the same conditions, the nox concentrations reduced 12.5%, but for hydrogen at ø =1.3 the spark timing became critical condition, where advancing or retarding the spark timing made abnormal combustion conditions, and caused engine failure, because of this there is no curve representing hydrogen behavior. the figures give emphasis that the spark timing effect is very limited at rich side because of oxygen lack. fig.10. studying spark timing effect on nox concentrations for specific rich equivalence ratio, for each fuel used in the study, when the engine worked at each fuel hucr. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ miqdam t. chaichan al-khwarizmi engineering journal, vol. 6, no. 2, pp 11-20 (2010) 18 4. conclusions 1. nox concentrations increased with cr increased at lean and rich sides. the maximum value for these concentrations reduced with cr increased. 2. nox concentrations resulted from using hydrogen gave the maximum values compared with other fuels resulted concentrations, weather the engine run at hucr for each fuel or at constant cr=8:1, because of its high burning velocity. 3. lpg fuel pass over gasoline and ng in emitted nox, and win the second rank in higher nox concentration. 4. equivalence ratio can be used as restricting variable by operating engine with very lean mixtures. 5. spark timing can be considered as the main factor in controlling nox concentration resulted from the engine, when it works with one of the studied hydrocarbon fuels. retarding the spark timing reduce nox concentrations highly. 6. with hydrogen as engine fuel, changing spark timing from the optimum timing cause abnormal combustion, so the work will be limited with optimum timing, except for very lean equivalence ratios less than ø =0.7, retarding spark timing appears its usual effect. nomenclature lpg liquefied petroleum gas ng natural gas nox nitrogen oxides cr compression ratio hucr higher useful compression ratio ost optimum spark timing sie spark ignition engine 5. references [1] goto, s. and fukuda, t. study of nox formation and reduction of lean-burn spark ignition gas engine, journal of the society of american engineers, vol. 19, no.14, pp: 351354, 1998. [2] szczepanski, d. factors influencing nox emissions at tarong and stanwell power stations, ph.d. thesis, the university of queensland, australia, 1998. [3] hermann, f., zeuch, t. and klingmann, j. the effect of diluents on the formation rate of nitrogen oxide in a premixed laminar flame, asme paper no gt2004-53841, 2004. [4] o'dell, p. r. why carbon fuels will dominate. the 21st century's global energy economy conference, brentwood, multi-science, 2004. [5] ladommatos, n. , abdelhalim, s. and zhao, h. control of oxides of nitrogen from diesel engines using diluents while minimizing the impact on particulate pollutants, journal of applied thermal engineering, vol. 16, no. 3, pp: 963-980, 1998. [6] ouellette, p., douville, b., hill, p. g. and ursu, b. nox reduction in a directly injected natural gas engine, proceedings of the 1998 fall technical conference of the asme, ic engines division, ice vol. 31, no.3, september, 1998. [7] michaels, h. c. and fulper, b. k. nitrous oxide emission factors for mobile sources us epa. presented at the awma emissions inventory conference, new orleans, la, 1998. [8] soltic, p. and hausberger, s. on-road emission measurements and emission modeling results for a tractor-semi trailer in trans-alpine operation, 13th international scientific symposium transport and air pollution boulder, colorado, usa, september 13-15, 2004. [9] chaichan, m. t. study of nox and co emissions for si engine fueled with different kinds of hydrocarbon fuels, arabic universities union journal, vol. 13, no.2, pp:85-105, 2006. [10] kaleemuddin, s. and roa, g. a. p. development of duel fuel single cylinder natural gas engine an analysis and experimental investigation for performance and emissions, american journal for applied science, vol. 6, no.5, pp: 929-936, 2009. [11] backer, s. r. a. and ismail, a. r. green engine development using compressed natural gas as an alternative fuel: a review, american journal of environmental sciences, vol. 5, no. 3, p 371-381, 2009. [12] bose, r. s. c., monohar, b. and muthuraman, s. study of combustion phenomena in petrol engine for proper development of power with less detonation, research journal of applied sciences, vol. 2, no.4, p249-356, 2007. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ miqdam t. chaichan al-khwarizmi engineering journal, vol. 6, no. 2, pp 11-20 (2010) 19 [13] al baghdadi, m. a. r. a simulation model for a single cylinder four stroke spark ignition engine fueled with alternative fuels, turkish journal for engineering and environment science, vol.30, pp 331-350, 2006. [14] rahman, m. m., mohammed, k. m., backer, r. a. and sani, m. s. m. study of air fuel ratio and instantaneous behavior on crank angle of four cylinder direct injection hydrogen fueled engine, proceeding of the world congress on engineering, vol ii, july 1-3, london, uk, 2009. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ )2010( 20-11 ، صفحة2، العدد 6یة المجلد مجلة الخوارزمي الھندس مقدام طارق جیجان 20 لمحرك اشتعال بالشرارة یعمل بأنواع مختلفة من الوقود noxدراسة ملوثات الھیدروكاربوني والھیدروجین **قحطان عدنان عباس *مقدام طارق جیجان الجامعة التكنولوجیة /قسم ھندسة المكائن والمعدات miqdam_tc@hotmail.com: البرید االلكتروني* qahtan_alnakeen@yahoo.com :البرید االلكتروني ** الخالصة وع رارة ن ل بالش ي یعم ات ricardo e6 استخدم الغاز النفطي المسال والغاز الطبیعي والھیدروجین لتشغیل محرك احتراق داخل ة ملوث nox، ومقارن .المنبعثة من المحرك مع مثیالتھا عند عمل المحرك بالجازولین ود 8:1تمت دراسة الملوثات الناتجة عند عمل المحرك بنسبة االنضغاط النافعة العلیا للجازولین ل وق ا لك ة العلی غاط النافع بة االنض ھ بنس ا بعمل ، ومقارنتھ .rpm 1500ضغاط والنسبة المكافئة وتوقیت الشرر، عند عمل المحرك بسرعة ثابتة على حدة، ودرس تأثیر نسبة االن ات تكون دائما في الجانب الضعیف، وتقل التراكیز باالبتعاد عن ت noxأظھرت النتائج أن أعلى قیمة لملوثات ذة الملوث یط، وأن ھ انبي الخل بة لج لك النس ن 8:1تكون أعلى ما یمكن للغاز الھیدروجین عند نسبة انضغاط ود، ولك ل وق ا لك ة علی غاط نافع بة انض ، وتتقارب ألنواع الثالثة للوقود عند عمل المحرك بنس .ت كان لتوقیت الشرر، كما أن أكبر تأثیر على ھذة الملوثاnoxیبقى الھیدروجین ذو أعلى قیم لتراكیز this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ (microsoft word 13-25\343\315\323\344 \314\310\321 \346\315\323\355\344) al-khwarizmi engineering journal,vol. 13, no. 1, p.p. 1 solving the inverse kinematic equations of elastic robot arm utilizing hussein m. al*department of mechanical **college of engineer *email: **email: (received 15 https://doi.org/10.22153/kej abstract the inverse kinematic equation for a robot is very important to of this equation is complex for the rigid robot due to structure of robot link. in light robot arms, than the rigid link robot because the deformation variables (elongation and bending) kinematic equation. the finding of an inverse kinematic equation and both of the end-effector position and deformations variables. in this work, a neural network solve the problem of inverse kinematic equation. to feed the neural network, experimental data were taken from an elastic robot arm for training the network, these data presented by joint angles, deformation variables and end positions. the results of network training showed a good fit targets data. in addition, this method for finding the inverse of kinematic equation proved its effectiveness and validation when applying the results of neural network real light robot’s position. keywords: elastic robot, forward and inverse kinematic equation of elastic robot. neural networks. 1. introduction the forward kinematic equation is a functional relationship between the generalized parameters (joint displacements) and the end positions. by substituting a set of values of generalized parameters into the forward kinematic equation, the considering ends – effector can be obtained. the problem of finding the end position for a given set of generalized parameters is called the direct kinematic problem robot’s end-effector positioning and control, it i required to find the generalized parameters that lead the end – effector to the specified position and orientation. this is done by finding the inverse of the forward kinematic equation (inverse khwarizmi engineering journal,vol. 13, no. 1, p.p. 1325 (2017) solving the inverse kinematic equations of elastic robot arm utilizing neural network -khafaji* muhsin j. jweeg** mechanical engineering / university of technology **college of engineering/ alnahrain university *email: hussalkhafaji@gamil.com **email: muhsinnah_eng@nahrainuniv.edu.iq 15 march 2016; accepted 14 november 2016) https://doi.org/10.22153/kej.2017.11.002 robot is very important to the control robot’s motion and position. the solving of this equation is complex for the rigid robot due to the dependency of this equation on the joint , where the flexibility exists, the solving of this problem is deformation variables (elongation and bending) are present kinematic equation. the finding of an inverse kinematic equation needs to obtain the relation between the joint angles effector position and deformations variables. in this work, a neural network has f inverse kinematic equation. to feed the neural network, experimental data were taken from an elastic robot arm for training the network, these data presented by joint angles, deformation variables and end ng showed a good fit between the output results of the neural network and the targets data. in addition, this method for finding the inverse of kinematic equation proved its effectiveness and neural network practically in the robot’s operating software for controlling orward and inverse kinematic equation of elastic robot. neural networks. the forward kinematic equation is a functional relationship between the generalized parameters (joint displacements) and the end – effector positions. by substituting a set of values of forward kinematic effector can be obtained. the problem of finding the end-effector position for a given set of generalized parameters called the direct kinematic problem [1]. in effector positioning and control, it is required to find the generalized parameters that effector to the specified position done by finding the inverse of the forward kinematic equation (inverse kinematic problem). the complexity of the inverse kinematic problem depends heavily on the number of joints and structure of the robot flexibility of robot arms will add additional in the forward kinematic equation presented by the deformation variables magnitude of these variables could estimated easily, because their magnitude upon external forces, inertia forces, positions and orientation of robot arms [3]. the importance of the inverse kinematic problems in robot control, and the complications of solving it, make many researches deal with this subject, and many methods investigated to solve the inverse kinematic equation. widely applied solution is the clos al-khwarizmi engineering journal solving the inverse kinematic equations of elastic robot arm control robot’s motion and position. the solving joint configuration and , the solving of this problem is more complicated present in the forward to obtain the relation between the joint angles has been proposed to f inverse kinematic equation. to feed the neural network, experimental data were taken from an elastic robot arm for training the network, these data presented by joint angles, deformation variables and end-effector between the output results of the neural network and the targets data. in addition, this method for finding the inverse of kinematic equation proved its effectiveness and ly in the robot’s operating software for controlling the orward and inverse kinematic equation of elastic robot. neural networks. kinematic problem). the complexity of the problem depends heavily on the number of joints and structure of the robot [2]. of robot arms will add additional terms in the forward kinematic equation, these terms presented by the deformation variables. the nitude of these variables could be not magnitude depends upon external forces, inertia forces, positions and of the inverse kinematic problems in robot control, and the complications of solving it, make many researches deal with this subject, and many methods investigated to solve the common and widely applied solution is the closed form hussein m. al-khafaji al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 1325(2017) 14 solution, literatures [3-8] presented different methods of closed form. a closed form solution is not always a possible way to find the solution, so various studies have been proposed using other techniques. juan et. al. [4] suggested the using of a fuzzy reasoning system to position the arm of an articulated robot without explicitly solving the inverse kinematic equation. yong et. al. [5] used genetic algorithm to solve the inverse kinematic. kuroe et. al. [11, 12] stated the use of neural networks as a new method of solving the inverse kinematics of a rigid robot manipulator. previous research [13-15] examined the use of artificial neural networks to find the inverse kinematic equation for articulated robots. while, shiv et. al. [6] applied neuro-fuzzy to obtain the inverse kinematic equation for robot with three degrees of freedom. most of researches proposed their solutions for the mathematical model of a rigid manipulator. with the presence of deflection parameters, the problem will be more complicated. therefore, in this work, the proposed neural network with multiple layers was suggested as a function approximation to find the inverse kinematic equation for an elastic robot arm (era). the multiple layer neural network is useful for function approximation because [15]: • it is universal approximations. • it is efficient approximations. • it could be implemented as a learning machine. 2. kinematic equations of an elastic robot arm (with error) the flexibility causes elastic deformations of the structural members of the manipulator, resulting in large end-effector errors, especially in long reach manipulator systems. hence, as a result, the frames defined at the manipulator joints are displaced from their expected locations. so, the use of kinematic equation of the rigid robot to position the manipulator end–effector will place the manipulator in a different position than the desired one. in figure 1, the frame oi-1 is the base frame , oi i is the ideal location and oi a is the actual location due to the deflection. fig. 1. frame displacement due to errors the transformation equation between the coordinates o �a and o �i consists of two parts, rotation and translation. according to the euler angle principle, the rotation part is the result of three sets of rotations which are roll, pitch and yaw about the axes z, y, x, respectively. the sequence of rotation is: erai � rot z, d�� rot y, d�� rot x, d�� …(1) that is a rotation of d� about the x axis, followed by a rotation d� about the y axis and finally a rotation of d� about the z axis. rot x, d�� � �1 0 0 00 cos d� �sin d� 00 sin d� cos d� 00 0 0 1� …(2) rot y, d�� � �cos d� 0 �sin d� 0 0 1 0 0 sin d� 0 cos d� 0 0 0 0 1 � …(3) rot(z, d�� � �cos d� �sin d� 0 0sin d� cos d� 0 00 0 1 00 0 0 1�…(4) era i � ���� b�! c�" 0�!� b!! c!" 0�"� b"! c"" 00 0 0 1� …(5) where: a�� � cos d� cos d� a!� � sin d� cos d� a"�� �sin d� b�!#cos d� sin d� sin d��sin d� cos d� b!! � sin d� sin d� sin d�$cos d� cos d� b"! � cos d� sin d� hussein m. al-khafaji al c�" � cos d� sin d� cos d�$ sin d� sin d� c!" � sin d� sin d� cos d�� cos d� sin d� c"" � cos d� cos d� the equation …(5) represents the rotation part of the transformation matrix. the translation matrix is: eta i � �1 0 0 δx0 1 0 δy0 0 1 δz0 0 0 1 � the transformation between coordinates and o �i becomes: ea i � eta i era i e' ( � ���� b�! c�" δx�!� b!! c!" δy�"� b"! c"" δz0 0 0 1 � here, the δx, δy, δz, d�, d� and d� generalized error parameters. usually generalized parameters are introduced on the basis of different approximations, such as assumed modes, finite elements, or ritz-kantorovich expansions, with different implications on the model complexity and accuracy [9]. the references [17-19] have supposed that the generalized deflection parameters are small, so a first order approximation can be applied to their trigonometric functions and product, and higher order equals zero. sin d� = d� , sin d� = d� sin d� = d� cos d� =cos d� =cos d� =1 based on these assumptions, the matrix …(8) will be equal to: e)*+, � � 1 �d� d� δxd� 1 �d� δy�d� d� 1 δz0 0 0 1 � in this work, the values of deflection’s are taken in consideration. figure 1 shows the coordinate for flexible links, the kinematic equation covering the positions of this links with presence of flexibility is: t)*+,=a�-.q�/ea 1 i 1 a!�.q!/ea 2 i2 ⋯an n1�.qn / al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 1 15 represents the rotation part of the transformation matrix. the translation matrix …(6) the transformation between coordinates o �a …(7) …(8) � are called generalized error parameters. usually, these generalized parameters are introduced on the basis such as assumed kantorovich expansions, with different implications on the have supposed that the generalized deflection parameters are small, so a first order approximation can be applied to their trigonometric functions and product, and higher the matrix ea i in � … (9) deflection’s parameters shows the coordinate for serial of the kinematic equation covering the links with presence of flexibility . /ea n i n …(10) an n1� is the homogenous transformation matrix in denavithartenber (dh) equation a221� � �cos 32 � sin 32 cos 42 sin 32sin 32 cos 32 cos 42 �cos 30 sin 42 cos0 0 where: 32 , 42 , ai and d2 represent the joint parameter defined as in figure 2. by using equation (10), the transformation relationship between the two frames can be found. fig. 2. the denavit-hartenberg notatio t)*+, may be expressed in form as a nonlinear function of q and t)*+, � 5 q, 7� where: t)*+, is the set of cartesian coordinates describing the position and orientation of the manipulator’s endeffector with respect to the inertial frame. q � 8q� q! ⋯ ⋯ ⋯ ⋯ 7 � 87� 7 ! ⋯ ⋯ ⋯ ⋯ khwarizmi engineering journal, vol. 13, no. 1, p.p. 1325(2017) ansformation matrix in (dh) equation (11): 32 sin 42 ai cos 3232 sin 42 ai sin 32cos 42 d20 1 � … (11) represent the joint parameter , the transformation relationship between the two frames o �a and o�1� hartenberg notatio. may be expressed in a simple compact form as a nonlinear function of q and 7 vectors: …(12) is the set of cartesian coordinates describing the position and orientation of the effector with respect to the ⋯ q9:; …(13) ⋯ 7 <:= …(14) hussein m. al-khafaji al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 1325(2017) 16 7 � 8δx> δy> δz? d�> d�> d�>:= …(15) where: q is the vector in joint space. 7 is a dimensional link deflection vector space, spanned to be the link deflections of the manipulator arm. n is the number of joints. @ generally equals to 6 x m. m is the number of flexible links. the elements of the vector 7 cannot easily specify their values, since these elastic coordinates are dependent on the rigid coordinate q and on the applied forces f. for more generally: 7 � a f, q� …(16) by substituting equation …(16) into equation (12), t)*+, will be: t)*+, � 5 q, e f, q�� …(17) as mentioned in the previous section, the two degrees of freedom of the arm robot manipulator used in this study are confined to move within the vertical plane, and so is the deformation of each link. hence, there is no rotation about the axes x and y, also there is no transformation in the z direction (the parameters δz, d� and d� are equal zero). figure 3 shows a single flexible link coordinate system, the o21� represents the base local coordinate system, and the frame o 2( is the local coordinate system assigned to link i in its undeformed position, while the o 2a is the actual local coordinate system of link i , when it is under deformation. the homogenous transformation matrix for this single link was derived as follow: • according to the motion of the links within the vertical plane, the homogenous transformation matrix e2a ( between o 2a and o 2i becomes: e2' 2( � �cosd� �sind� 0 δxsin d� cos d� 0 δy0 0 1 00 0 0 1 � …(18) • the homogenous transformation matrix between the o �i and o�1� is presented by the matrix a��1� in equation (9). • the homogeneous transformation matrix for this a single link is found from the relations (12) and (18). t2c21�' � a221�' e2' 2( …(19) t2c21� � �t�� t�! t�" t�et!� t!! t!" t!et"� t"! t"" t"e0 0 0 1 � …(20) where: f2 � fgh 32 h2 � sin 32 f42 � cos 42 h42 � sin42 fi2 � cosi�2 hi2 � sini�2 t�� � f2fi2 � f42h2hi2 t!� � s�cd� $ sd�cα�c� t"� � h42hi2 t�! � �f2hi2 � f42h2fi2 t!! � �h2hi2 $ f2fi2f42 t"! � h42fi2 t�" � h42h2 t!" � �h42f2 t"" � f42 t�e � f28kl2 $ �2: � f42h2km2 t!e � h28kl2 $ �2: $ km2f42f2 t"e � h42km2 $ d2 fig. 3. the coordinates system of a single flexible link under deformation. as shown in figure 4, the total kinematic equation of flexible robot of two degrees of freedom is: t)*+, � t�cn' t!c�' …(21) hussein m. al-khafaji al the transformation matrix of robot in general form is: t)*+, � �op gp qp rpos gs qs rsot gt qt rt0 0 0 1 � where: fig. 4. the coordinates systems of two elastic links and the angles of joints nu � c�c!8cd!sd�cα� $ cα�cd�cα!sd!� s�s!8sd�cd! $ cd�c$ c!s�8cd�cd! � sd�sd$ c�s!8cd!cd�cα�� sd�cα�sd!cα!:� c�8sα�sd!sα!: nv � c!8sα�sd�cd! $ sα�cd�cα!sd!:$ s!8sα�cd�cd!� sα�sd�sd!cα!: $ cα ow � s�s!8cα�sd�cα!cd! $ cα�cd�sd!� c�c!8cd�sd! $ sd�cd$ c�s!8sd�sd! � cd�cα$ s�c!8cα�cd�cd!� cα�sd�sd!cα!:$ s�sα�sα!cd! al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 1 17 robot in general …(22) nw � c�c!8cd�cd! � sd�sd!cα!� c�s!8cd�cα!sd$ s�s!8cα�cα!sd� cα�cd�cd!:� c!s�8cd!sd�c$ cα�cd�cα!sd!$ s�sα�sα!sd! the coordinates systems of two elastic links and the angles of joints. !:cα!sd!:sd!cα!: …(24) α�sd!sα! …(25) … 25� !:cd!cα!:α!cd!: … 26� ou � c�c!8cd�cα�cd!cα! � sd�c� s�c!8sd�cd!c� c�s!8cd�cα�sd$ sd�cα�cα!cd!$ s�s!8sd�sd! �� c�8sα�sα!cd! ov � c!8sα�cd�cd!cα! � sα�sd$ s!8sα�cd�sd!� sα�sd�cα!cd! tw � c�s!cd�sα! � s�s!cα�sd�s$ c�c!sd�sα! $$ s�sα�cα! tu � s�s!cd�sα! $ c�s!sd�cα�s$ s�c!sd�sα! �� c�sα�cα! tv � s!sα�sd�sα! � c!sα�cd�sα khwarizmi engineering journal, vol. 13, no. 1, p.p. 1325(2017) !:sd! $ sd�cd!:sd�sd!: cα�!: …(23) cα�sd!:cα! $ cd�sd!:sd!!:� cd�cα!cd!:!: … 27� sd�sd!:!!: $ cα�sα!cd! … 28� sα!$ s�c!cα�cd�sα! … 29� sα!� c!cd�cα�sα! … (30) α! $ cα�cα! … (31) hussein m. al-khafaji al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 1325(2017) 18 rp � f�f!8fi� kl! $ �!� � hi�km!f4!:� f�h!8fi�f4!km!$ hi� kl! $ �!�:� h�f!8f4�hi� kl! $ �!�$ f4�fi�km!f4!:$ h�h!8f4�hi�f4!km!� f4�fi� kl! $ �!�:$ h4�h�h4!km! $ h4�h�i!$ f� kl� $ ��� � f4�h�km� … (32) pu � s�c!8cd� δx! $ a!� � sd�δy!cα!:� s�s!8sd� δx! $ a!�$ cd�cα!δy!:$ c�c!8sd�cα� δx! $ a!�$ cd�cα�δy!cα!:$ c�s!8cd�cα� δx! $ a!�� sd�cα�cα!δy!: $ c�8cα�δy�� sα�sα!δy! � sα�d!:$ s�8δx� $ a�: … 33� pv � c!8sα�sd� δx! $ a!� $ sα�cd�δy!cα!:$ s!8sα�cd� δx! $ a!�� sα�sd�cα!δy!: $ cα�sα!δy!$ cα�d! $ sα�δy� $ d� … 34� c� � cos θ� cd� � cos dϕ� cα� � cosα� s� � sin θ� sd� � sin dϕ� sα� � sin α� the degree of freedom of the robot arm manipulator which is used in this work, is two degrees of freedom, and confined to move within the vertical plane with the kinematic parameters listed in the table 1�. table table table table 1111,,,, the parameters of two linksthe parameters of two linksthe parameters of two linksthe parameters of two links.... jointsjointsjointsjoints pq ddddq rq aaaai i i i 1111 θ� 0 0 a1 2222 ps 0000 0000 aaaa2222 by substituting the values of parameters of the manipulator from the table 1� in to the equations 23� to 34� and with triangular operations, these equations will be as follow: nw � 8c�!:8cd�!: � 8s�!:8sd�!: … 35� nu � c�c!8sd�!: $ s�s!8sd�1!: $ c!s�8cd�1!:$ c�s!8cd�!: … 36� nv � 0 … 37� ow � s�s!8sd�1!: � c�c!8sd�!: � c�s!8cd�1!: � s�c!8cd�!: … 38� ou � c�!8cd�!: � s�!8sd�1!:: … 39� ov � 0 … 40� tw � 0 … 41� tu � 0 … 42� tv � 1 … 43� pw � c�c!8cd� δx! $ a!� � sd�δy!:� c�s!8cd�δy!$ sd� δx! $ a!�:� s�c!8sd� δx! $ a!�$ cd�δy!: $ s�s!8sd�δy!� cd� δx! $ a!�: $ c� δx�$ a�� � s�δy� … 44� pu � s�c!8cd� δx! $ a!� � sd�δy!:� s�s!8sd� δx! $ a!�$ cd�δy!: $ c�c!8sd� δx!$ a!� $ cd�δy!:$ c�s!8cd� δx! $ a!�� sd�δy!: $ c�δy� $ s�8δx�$ a�: … 45� pv � 0 … 46� where: c�! � cos θ� $ θ!� s�! � sin θ� $ θ!� cd�! � cos dϕ� $ dϕ!� sd�! � sin dϕ� $ dϕ!� cd�1! � cos dϕ� � dϕ!� sd�1! � sin dϕ� � dϕ!� equations (44) to (46) represent the endeffector position with presence of flexibility of robot, which will be called, the flexible kinematic equation. the inverse of these equations will be found by using the neural network. 3. experimental work a. the rig of experiment in this work, the test rig was represented by two degrees’ manipulator (two elastic links) confined to move in a vertical plane. the two links were designed to have properties gathering the lightness approximate to the flexible beam and stiffness approximate to the rigid beam to reduce the vibration effects; the two links are hallow rectangular beams made from the aluminum type (6061-t6) with length 57 cm and 62 cm for first and second arm, respectively. in addition, the manipulator has a measurement system (bonded hussein m. al-khafaji al strain gauges on each arm) and data acquisition system to measure the deflection variable the rotation of the tip of the beam experimentally, the measuring of the deflections at two points along the beam was done points where the strain gauge no.3 and at the tip, and by applying these values of the deflections into the following equation [20] : tan i� � ∆xs∆p where: δy represent the deflection. ∆δy represents the difference between the two deflections. ∆l represents the distance between the two points where the deflections measured. the relations between the deflections and the voltages of strain gauges were estimated experimentally by curve fitting between deflection and voltage as shown in figure 5. for link-1: the relation between the tip deflection and the voltage of the strain gauge no.1 is: kmy2z � 0.0026 { $ 8 | 101} the relation between the tip deflection and the voltage of the strain gauge no.2 is: kmy2z � 0.001 { $ 3 | 101} the relation between the deflection at the point 31cm from the center of the shaft of the first joint and the voltage of the strain gauge no.3 is:kmcy "� ~> � 0.0008 { � 2 | 101} the link-2: the relation between the tip deflection and the voltage of the strain gauge no.1 is: kmy2z � 0.0016 { $ 6 | 101} the relation between the tip deflection and the voltage of the strain gauge no.2 is:kmy2z � 0.0022 { $ 3 | 101} the relation between the deflection at the point 36 cm from the center of the shaft of the second joint and the voltage of the strain gauge no.3 is: kmcy "� ~> � 0.0022 { � 3 | 101} kl was experimentally found by extracting the strain from two sensors at the upper and lower surface at the same position of the strain gauge no.1 and no. 2. the difference value represents the extension of the beam in the longitudinal direction, as represented by the relationkl � 7. � al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 1 19 strain gauges on each arm) and data acquisition deflection variable, to find the rotation of the tip of the beam dϕ experimentally, the measuring of the deflections at two points along the beam was done at the points where the strain gauge no.3 and at the tip, values of the deflections … (47) the difference between the two represents the distance between the two the relations between the deflections and the voltages of strain gauges were estimated between deflection the relation between the tip deflection and the …(48) the relation between the tip deflection and the …(49) the relation between the deflection at the from the center of the shaft of the first joint and the voltage of the strain gauge no.3 is: …(50) the relation between the tip deflection and the …(51) the relation between the tip deflection and the voltage of the strain gauge no.2 is: …(52) the relation between the deflection at the point 36 cm from the center of the shaft of the and the voltage of the strain gauge …(53) was experimentally found by extracting the strain from two sensors at the upper and lower surface at the same position of the strain gauge difference value represents the extension of the beam in the longitudinal direction, as represented by the relation [20]: …(54) figure 6 shows the two degrees robot arm manipulator and the strain gages. fig. 5. the distribution of strain gauges and applied load for the two links. fig. 6. the two degrees robot arm manipulator and the strain gages. link-2 link-1 khwarizmi engineering journal, vol. 13, no. 1, p.p. 1325(2017) 6 shows the two degrees robot arm manipulator and the strain gages. the distribution of strain gauges and applied the two degrees robot arm manipulator and hussein m. al-khafaji al b. collection of data the experimental data for feeding the neural networks for training include joint’s angle, deformation variables and corresponding end effector positions. to collect data, a control mode was designed to operate the robot sequence of motions, which include moving the first links in a range of angles (0 to 30 and the second link ( -35o to 60o step 5 the control mode is activated, the first link at angle 0o, and the second link is still a while at the start angle, then moves 5o to the next step after completion the range of angles, arm returns back to the start angle, and the first joint moves 5o to next step and so on. at each step (position), the deformation variable effector position were measured automatically. this procedure was repeated for four values of load (0,1,2, and 3) kg hang the end of the link two. the number for each parameter was 560 reading, which will be used for training neural network. figure the samples of positions during this test. fig. 7. samples of positions during experimental work. some samples of the results of the deformation parameters, which were read in above shown in the figures (figure 8 to figure figures represent the change of values for and d� at the tip with angles of the two links these results were used as inputs to equations (44) and (45) to calculate the end effector in x and y coordinate that would be with the measured generalized parameters as input values to the neural network. al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 1 20 for feeding the neural include joint’s angle, corresponding enda control mode was designed to operate the robot in specific ch include moving the 30o step 5o ) step 5o). when , the first link is still , and the second link is still a while at to the next step. , the second returns back to the start angle, and the first . at each step and end and saved . this procedure was repeated for ,1,2, and 3) kg hanging at of readings which will be figure 7 shows of positions during this test. samples of positions during experimental deformation , which were read in above test, are figure 13), these represent the change of values for δ�, δ� at the tip with angles of the two links. these results were used as inputs to equations calculate the end effector in x and y coordinate that would be with the measured generalized parameters as input values to the fig.8 δx vs. θ2 at θ1=4 deg. link fig. 9. δy vs. θ2 at θ1=0 deg. link fig. 10. dϕ vs. θ2 at θ1=0 deg. link fig. 11. δx vs. θ2 deg. link khwarizmi engineering journal, vol. 13, no. 1, p.p. 1325(2017) θ1=4 deg. link-1. θ1=0 deg. link-1. θ1=0 deg. link-1. θ2 deg. link-2. hussein m. al-khafaji al fig. 12. δy vs. θ2 deg. link-2 fig. 13 dϕ vs. θ2 deg. link-2 4. neural network for inverse k equation of elastic robot as mentioned in previous section, there is difficulty to solve the problem for finding the inverse of the kinematic equation with presence the deformation parameters. so, to overcome this difficulty, the neural network was used inverse of the kinematic equations (4 these equations relate the vector of operating (task) space coordinate to the joints and deformations vector, these equations could be presented in compact form: � � 5 �, 7� where: � � 8rp, rs: , rt � 0 � � 83�, 3!: 7 � �kl1, km1, i�1, kl2, km2, i�2� the inverse kinematic problem of rigid robot is defined as giving end effector positions ( the joint variable vector (��, in the elastic robot beside the vector ( � ), there will deformations vector 7 that should be given to get (��. so, the inverse equation will be: al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 1 21 2. 2. kinematic section, there is a difficulty to solve the problem for finding the inverse of the kinematic equation with presence of so, to overcome this used to find the (44) to (46). the vector of operating (task) space coordinate to the joints and deformations vector, these equations could be …(55) …(56) …(57) � …(58) the inverse kinematic problem of rigid robot is d effector positions (�) to get elastic robot. there will be the should be given to get � � 51� �, 7� the proposed neural network was used to model the equation (59), which kinematic inverse neural network. many neural networks were trained. the structure of each network was with (one two hidden layers-output layer). each network had a different number of neurons in the hidden layers. the numbers was chosen randomly. the selection of neurons number was specified by trial and error. the input layer received the eight variables (δy1, δx1, dϕ1, δy2, δ py). the output layer gave the angles ( network result, as shown in figure 1 fig. 14. the structure of kinematic inverse neural network. the transfer function (τ) used in the hidden layers for each network was the hyperbolic tangent function (due to the bipolar value for the output of the function) as shown in equatioτ x� � tanh l� � *��1*���*���*��� where � is the slope parameter. for the output layer was pure line. the back propagation training algorithm with one variable learning rate was used to train these neural networks. the input variables (δy1, δx1, d dϕ2) were imported from the results of the test in the part of experimental work and by using these variables with corresponding angles ( in equations (44) and (46) to calculate the last two variables (px and py). hence, these variables were used to train the networks. the networks that used were simulated by using the scientific and engineering package matlab. to find the optimum neural network, the tested networks output was compared with respect to the khwarizmi engineering journal, vol. 13, no. 1, p.p. 1325(2017) …(59) the proposed neural network was used to which is called the kinematic inverse neural network. in this work, many neural networks were trained. the structure one input layer and output layer). each network had a different number of neurons in the hidden layers. the numbers was chosen randomly. the selection of neurons number was specified by trial received the eight δy2, δx2, dϕ2, px, and py). the output layer gave the angles (θ1, θ2) as a figure 14. the structure of kinematic inverse neural used in the hidden layers for each network was the hyperbolic tangent function (due to the bipolar value for the as shown in equation [21]: …(60) is the slope parameter. the output layer was pure line. the back propagation training algorithm with one variable learning rate was used to train these neural δ δx1, dϕ1, δy2, δx2, 2) were imported from the results of the test in experimental work and by using these variables with corresponding angles (θ1 and θ2 ) to calculate the last two variables (px and py). hence, these variables were were simulated by using the scientific and engineering package to find the optimum neural network, the tested compared with respect to the hussein m. al-khafaji al angles that were used in equations (44) get px and py. the best fit obtaine network has the following structure, as shown in figure 14: 1one input layer (receives the eight variables). 2two hidden layers: an=15 neurons in the first hidden layer. bk=13 neurons in second hidden layer. 3one output layer (gives two outputs). the network training parameters that used in this network are listed as follow: training parameters value epochs 5000 goal 1×10-8 minimum gradient 1×10-10 learning rate 1×10-5 learning increment 0.9 5. results and discussion figures 15 and 16 show the comparison between the optimum neural network outputs and the target data for (θ1 and respectively. these figures reveal a good fitting between the network results and the target angles the roots square errors of result networ (0.999742) and (0.999804) for the first and the second angles, respectively. fig. 15. the comparison between θ1 target and onn. al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 1 22 ) and (45) to get px and py. the best fit obtained with the network has the following structure, as shown in one input layer (receives the eight variables). hidden layer. hidden layer. one output layer (gives two outputs). network training parameters that used in this 8 10 5 show the comparison between the optimum neural network (onn) outputs and the target data for (θ1 and θ2), respectively. these figures reveal a good fitting between the network results and the target angles. of result network were (0.999742) and (0.999804) for the first and the θ1 target and θ1 fig. 16 the comparison between θ onn. figures 17 and 18 depict the comparison between the px and py, that resulted from the equations (44) and (45) with the neural network. each figure has two curves; the first one is from applying the target angles, and the second one is resulted from applying the onn. the figures from 15 to 18 show a good fitting between the neural network results and the target angles, so that the results of this were used in the control system of the elastic robot to control the motion and position fig. 17 the comparison between px target and px onn. fig. 18. the comparison between py target and py onn. khwarizmi engineering journal, vol. 13, no. 1, p.p. 1325(2017) the comparison between θ2 target and θ2 depict the comparison resulted from the the neural network. each figure has two curves; the first one is from applying the target angles, and the second one is nn. show a good fitting network results and the target the results of this neural network control system of the elastic robot to control the motion and position. the comparison between px target and px the comparison between py target and py hussein m. al-khafaji al as mentioned above, there are many networks with different structures that were experimented to find the best one. at the beginning, the networks were with one hidden layer trained, but the results were far from the target in spite of increasing the number of neurons. therefore using networks with two hidden layers, the result began to approach from the target. figure 22 illustrate the results for some of the networks that were experimented. the way that these networks were named depended upon how many neurons were used in each layer, so the name (network 12-40) means the first layer has 12 neurons, and the second layer has 40 neurons. fig.19. θ1 target vs.θ1 neural network two layers fig. 20. θ1 target vs. θ1 neural network two layers fig. 21. θ2 target vs. θ2 neural network two layers al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 1 23 as mentioned above, there are many networks were experimented to find the best one. at the beginning, the with one hidden layer trained, but the results were far from the target in spite of therefore, by using networks with two hidden layers, the result figures 19 to for some of the networks that were experimented. the way that these networks were named depended upon how many neurons were used in each layer, so the name 40) means the first layer has 12 neurons, and the second layer has 40 neurons. 1 neural network two layers. 1 neural network two layers. 2 neural network two layers. fig. 22. θ2 target vs. θ2 neural network two layers 6. conclusion the first advantage of using neural network is to overcome the difficulties of kinematic inverse equation of the flexible robot, and the advantage is that it takes the values of training from the experimental work by operating the robot itself, and measures the variables with presence of more than one effect during the operation (like joint’s stiffens, joint’s gear box backlash, noise, etc..). these effects will in consideration to establish the network automatically (during learning to find approximation), therefore, the result when used in the control system of robot will overcome the problem of these effects, but may be when using the other methods algebraic method, the inverse kinematic equation will be solved mathematically and consideration these effects. the proposed neural network gave a good fit with the target. the roots square errors of results network were and (0.999804) for the first and the second angles, respectively. and it is found from the training and testing of many networks that, not conditionally, the increase of number of neurons in the hidden layers will give the best result. also, this neural network was used in the operating software of era robot and showed a good performance to position the end effector of the elastic 7. references [1] slotine, h. asada and j. j. e., robot analysis and control, new york: john wiley and sons, 1985. [2] manseur, rachid, robot modeling and kineamtics, india : firwall media, 2007. [3] bingul, serdar kucuk and zafer, "the inverse kinematics solutions of industrial khwarizmi engineering journal, vol. 13, no. 1, p.p. 1325(2017) 2 neural network two layers. the first advantage of using neural network is to overcome the difficulties of kinematic inverse equation of the flexible robot, and the second the values of training from the experimental work by operating the the variables with presence of more than one effect during the operation (like joint’s stiffens, joint’s gear box hese effects will be taken in consideration to establish the network automatically (during learning to find the function he result of network when used in the control system of robot will overcome the problem of these effects, but may be the other methods, especially the the inverse kinematic equation l be solved mathematically and will not take in the proposed neural network gave a good fit with the target. the roots of results network were (0.999742) and (0.999804) for the first and the second angles, tively. and it is found from the training and testing of many networks that, not conditionally, the increase of number of neurons in the hidden layers will give the best result. also, this neural network was used in the operating software of a good performance to elastic robot. slotine, h. asada and j. j. e., robot analysis and control, new york: john wiley manseur, rachid, robot modeling and kineamtics, india : firwall media, 2007. bingul, serdar kucuk and zafer, "the inverse kinematics solutions of industrial hussein m. al-khafaji al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 1325(2017) 24 robot manipulators," in mechatronics, 2004. icm '04. proceedings of the ieee international conference on, 3-5 june 2004. [4] albert castellet and federico thomas, "towards an efficient interval method for solving inverse kinematic problems," in pp. 3615-3620, ieee international conference on robotics and automation, new mexico, april, 1997. [5] michael wenz and heinz wörn, "solving the inverse kinematics problem symbolically by means of knowledge-based and linear algebra-based methods," in ieee conference on emerging technologies and factory automation, pp. 1346-1353, 2007. [6] jian xie, wenyi qiang, bin liang and cheng li, "inverse kinematics problem for 6-dof space manipulator based on the theory of screws," in international conference on robotics and biomimetics,ieee, sanya, china, december 15-18 2007. [7] e. sariyildiz and h. temeltas, "solution of inverse kinematic problem for serial robot using dual quaterninons and plücker coordinates," in advanced intelligent mechatronics, ieee/ asme international conference on , singapor, 2009 . 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[12] yasuaki kuroe, yasuhiro nakai and takehiro mori, "a neural network learning of nonlinger mappings with considering their smoothness and its application to inverse kinematics," in industrial electronic, control and instrumentation, 20th international conference on ( volume 2). ieee, 1994. [13] jolly shah, s. s. rattan, b.c. nakra , "kinematic analysis of a planer robot using artificial neural network," international journal of robotics and automation (ijra), vol. 1, no. 3, pp. 145-151, september 2012. [14] panchanand jha, bb biswal, "a neural network approach for inverse kinematic of a scara manipulator," international journal of robotics and automation (ijra) , vol. 3, no. 1, pp. 52-61, march 2014. [15] adrianvasile duka , "neural network based inverse kinematic solution for trajectory tracking of a robotic arm," procedia technology , science direct, elsevier, 2014. [16] shiv manjaree , vijyant agarwal and b.c. nakra, "kinematic analysis using neurofuzzy intelligent technique for robotic manipulator," international journal of engineering research and technology , vol. 6 , no. 4, pp. 557-562, 2013. [17] u. y. x. a. t. y. hiroshi, "modeling and control strategy of a 3-d flexible space robot," in workshop on intelligent robots and systems iros, 1991. [18] c. s. d. p. d. j. h. a. j. f. mavroidis, "a systematic error analysis of robotic manipulators: application to high performance medical robot," in international conference in robotic and automation, albuquerque, 1997. [19] j. zhao-hui, "compensability of endeffector motion errors and evaluation of manipulability for flexible space robot arms," ieee, pp. 486-491, 1992. [20] stephen p. timoshenko and james m. gere, "mechanics of materials", book, londonbritain: van nostrand reinhold company ltd., 1978. [21] simon haykin, "neural networks and learnings machines", book, new jerseyunited states of america: pearson education, nc., 2009. ���� �� ���� � ��� 1، ا�� د13 ا��� ��� ا� ����� ا���ارز�� ،25-13 )2017( 25 � !� ��"�#$ �!�2 1$��0 ام ا�.+"$ت ا��,+�� ذي أذرع آ� �� ��"�س ا� �$د�� ا�"�� $� ���� ا���� ����* 34� !+ ����** *���������� / ()' ا!&%$#� ا! *+!+%� ا!/�.-� ا!, *�.-� ا!%&234 / 01�� ا!&%$#�** hussalkhafaji@gamil.com : ا8!�,4و�6 ا!$345 * muhsinnah_eng@nahrainuniv.edu.iq :ا8!�,4و�6 ا!$345 ** �� ا��5 �� !40و:+ت ��;� %��ان @l ھjه ا! -�د!� 3�+ن .-h$اً :�!%)�5 !40و:+ت و6f ا!)�4eة a)+. b0c ا!4و:+ت و@14,? ��+ن .& 3ان .-�+س ا! -�د!� ا! �l ا!4و:+ت�14�o ا! n�lm وھ; b0c �!د�ه ا! -jد ھ� ,cا o5(: o0p!ا . $hcن ا+��# lq!ن اrf ،دة+*+. ���+ن ا! 4و; t���n ا8ذرع @nx!ت ا�6 ا!4و:+;f �4ات ا!,y+ه 6f ا! -�د!� ا!z,. ]4ة !+*+د�5 )���� q3,�ج ا!b إ3/�د ا!-[(� .� :�2 زوا3� ا! n�lm و( a)+. 2. l1. ا8.�.��;� %��ان إ3/�د .-�+س ا! -�د!� ا! �4ات ا!,y+هz,.`6 !40و:+ت و�4ف ا!%&e!ا . ،l -!ا اj6 ھf ';����;� %���+س ا! -�د!� ا!-. �0�y. lq! ��5p-!ا ��5y!ام ا$x,#و ا(,4ح ا ��5y!�3 اjz,! 5p-!ا ����توا.$ادھ� ����ت ا!x��m :,$ر53&�، ;' ا#,�ل :��5!�: a)ه و.+ا+y,!4ات ا�z,. ،lm�n !ا �وا3e: f0g ; ت����0�� اjiت .2 رو:+ت .4ن، ;h0 ا!5 c �%e; f�h:. ا!4eف ا!%&�`6: ��5p-!ا ��5y!ا o3ر$; j`�,��' ا! 0e+:� ا*�$ �ان h!وا ��5y!ت ا�4*x. 2�: �. .]kf 2c h!س ان ذ+�ھjه ا!6f �h34e إ3/�د .nx!`6 !40و:+ت ا�4ف ا!%&e!ا a)+. $3$q,: �m�x!4ة اe�5�� l%. 6f+.� ا!)p-!ا ��5y!ا m�5e; $%c �&,�0c�f f,5nا ����;� %���o ا! 4نا! -�د!� ا!. al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 5, no. 1, pp 20-32 (2009) mass transfer coefficient during cathodic protection of low carbon steel in seawater khalid w. hameed * , anees abdullah khadom ** and ameel mohammed rahman * *department of biochemical engineering/ al-khwarizmi college of engineering/university of baghdad ** college of engineering/ university of daiyla (received 19 june 2008; accepted 13 january 2009) abstract the aim of this research is to calculate mass transfer coefficient, kd, during cathodic protection of low carbon steel in neutral seawater (3.5% w/v nacl in distilled water with ph = 7). two types of cathodic protection were used: first: sacrificial anode cathodic protection (sacp) were a pipeline of steel carrying seawater using zinc as a sacrificial anode and with variable temperatures ranged (0 – 45oc) and volumetric flow rate ranged (5 – 900 lit/hr). it was found that the kd increases with increasing temperature and volumetric flow rate of seawater, where kd ranged (0.24×10-6 – 41.6×10-6 m/s). second: impressed current cathodic protection (iccp) technique adopting a rotating vertical steel cylinder in seawater with variable temperatures ranged (0 – 45oc) and rotating velocity ranged (0 – 400 rpm). it was found that the kd increases with increasing temperature and rotating velocity, where kd ranged (7.25×10-6 – 36.82×10-6 m/s). keywords: cathodic protection, momentum transfer, reynolds number, carbon steel 1. introduction corrosion is an electrochemical process in which a current leaves a structure at the anode site, passes through an electrolyte and reenters the structure at the cathode site. current flows because of a potential difference between the anode and cathode that is the anode potential is more negative than the cathode potential, and the difference is the driving force for the corrosion current. the total system-anode, cathode, electrolyte and metallic connection between anode and cathode is termed a corrosion cell [shrier(1), 1976 and george, 1985]. cathodic protection involves the application of a direct current (dc) from an anode through the electrolyte to the surface to be protected. this is often through of as "overcoming" the corrosion currents that exist on the structure. there is no flow of electrical currents (electrons) through the electrolyte but flow of ionic current. cathodic protection eliminates the potential differences between the anodes and cathodes on the corroding surface. there are two proved methods of applying cathodic protection: sacrificial anode (galvanic) and impressed current. each method depends upon a number of economic and technical considerations and as certain advantages. for every structure, there is a special cathodic protection system dependent on the environment of the structure [scully, 1975]. when an electrode is polarized, the surface concentration of species that is either being oxidized or reduced fall to zero. additional material will then diffuse to the electrode surface towards this region of lower concentration. if the electrolysis experiment is carried out in an agitated solution, i.e. the solution is in motion with respect to the electrode or vise versa, then the resulting concentration-distance profile at the electrode surface can be represented as shown in figure (1) [trethewey and chamberlain, 1996 and roberge, 2004]. in the figure (1) the electrode is represented by bold bar in the left side of figure. the x-axis is a scalar and represents distance away from the electrode. they-axis represents concentration. the maximum concentration is represented by cb khalid w. hameed al-khwarizmi engineering journal, vol. 5, no. 1, pp 20-32 (2009) 21 which is its concentration in the bulk solution. in figure (1) there are two regions of concentration. because the solution is well mixed, in the bulk region the concentration is constant with respect to distance. this is represented by horizontal line where c = cb (this is known as the convective region). there is then a region where the concentration drops, falling to zero at the electrode surface. the diffusion layer associated with this drop has thickness δd. the exact thickness of the diffusion layer depends upon the nature of the solution into which it extends. for stirred aqueous solution the thickness of the diffusion layer can between 0.001 to 0.01 mm roberge, 2004]. fig.1. variation of an anion concentration with distance from electrode [roberge, 2004]. for an unstirred solution it is about 0.5 mm thick [uhlig, 1971]. in an important assumption of this mode is that when material reaches the surface of the electrode it is instantaneously oxidized or reduced thereby maintaining a zero concentration at the electrode surface. in practice, this is easy to achieve by selecting a suitable polarization voltage. it is clear that the concentration gradient in the diffusion layer, we not that it both linear and constant. it is can be represented gradient mathematically as:   d sb cc dx dc    ….(1) fick ’ s law of diffusion state that [shreir (1), 1976, and trethewey, 1996]: dx dc dj  …(2) where j is the flux of substance and d is a diffusion coefficient. it can be seen from faraday’s law of electrolyte that: zfji  …(3) where i is the current density, μa/cm 2 , z is the valancy number of electrons involved in reaction, eq/mol, and f is farady’s constant (96496), c/mol. from equations 1, 2, and 3:   d sb cc zfdi    …(4) the negative sign is conventional, it us the current is being carried away from the cathode (as hydroxyl ion). the magnitude of current is interesting only and since, cs can never be negative, and the magnitude of the current is great when cs = 0, again the maximum or limiting current density: d bc zfdi   …(5) notice that when cs > cb , the implication is that the concentration of species in the region of electrode is increasing. the resulting sign from negative to positive tell us the current is reversed [trethewey and chamberlain, 1996, hanson, 2000 and cottis, 2002]. the present work considered two types of cathodic protection. in the sacrificial anode cathodic protection , the effect of temperature (0 – 45 o c) and flow rate (5 – 900 lit/h) on the mass transfer coefficient, kd , are studied with constant ph = 7, duration time = 3 hrs and nacl in distilled water = 3.5% w/v. in the impressed current cathodic protection, the effect studied were temperature (0 – 45 o c), rotating velocity (0 – 400 rpm) on the kd with constant ph = 7 and nacl in distilled water = 3.5% w/v. 2. experimental work i. sacrificial anode cathodic protection system: working electrode (cathode): working electrode was tube specimen of low carbon steel with dimensions of 13.50 cm length, 2.68 cm inside diameter and 0.23 cm thick. anode c=cb c=cs bulk solution x=δd concentration x=0 electrode distance from electode khalid w. hameed al-khwarizmi engineering journal, vol. 5, no. 1, pp 20-32 (2009) 22 fig.2. schematic diagram of apparatus used in sacrificial anode test system. electrode: anode electrode was zinc strip with dimensions of 12.50 cm length, 1.00 cm width and 0.6 cm thick. the chemical composition of tube specimen of low carbon steel and zinc strip were analyzed by specialized institute of engineering industries were as shown in table (1) and (2) respectively. the apparatus shown in figure (2) [champion,1964] was used to study the variables, temperature (0 – 45 o c) and flow rate (5 – 900 lit/h] on corrosion rate or zinc consumption rate to compare with the mass transfer coefficient kd . after the container vessel was filled with seawater (3.5 % w/v nacl solution) adjusting ph to 7 and temperature to the desired values. the zinc strip was weighted and fixed at the inlet of the steel tube by rubber stopper and was electrically connected by an insulated copper wire to the steel tube outlet as shown figure (2). the zinc strip is extended along the steel tube to ensure uniform current and potential distribution along the tube wall. the seawater was pumped from the vessel by the pump through the rotameter to measure the desired flow rate, then the seawater inter from from the below the steel tube and out from upper the tube to return to the vessel again (i.e. the seawater is circulated between the vessel and steel tube). after each run the zinc strip was rinsed in distilled water and brush to remove the corrosion products, dried with clean tissue then immersed in the benzene and acetone, dried again and reweighted to determine the weight loss and prepare for another experiment. the steel tube is also rinsed and dried by the same way above in order to re-use another time. after each run the vessel is emptied from the solution and washed with distilled water, then filled wit a new prepared solution for a new run. table 1, chemical composition of low carbon steel c, % 0.1648 si, % 0.2540 mn, % 0.5101 s, % 0.0062 cr, % 0.0253 ni, % 0.0090 cu, % 0.1511 v, % 0.0034 fe, % rem. table 2, chemical composition of zinc strip al, % 0.12 pb, % 0.0034 cu, % 0.0017 cd, % 0.0033 fe, % 0.0032 sn, % 0.0023 zn, % rem. khalid w. hameed al-khwarizmi engineering journal, vol. 5, no. 1, pp 20-32 (2009) 23 13. power supply fig.3. schematic diagram of apparatus used in impressed current test system. ii. impressed current system: working electrode (cathode): working electrode was cylinder specimen of low carbon steel with dimensions of 1.58 cm length, 2.33 cm outside diameter and 0.18 cm thick. the composition of steel is the same of that of low carbon steel which was illustrated in table (1). auxiliary: electrode (anode): auxiliary electrode was a rod of high conductivity graphite, 4.5 cm length and 0.8 cm outside diameter. reference electrode: the cathode potential is determined with respect to saturated calomel electrode (sce). a luggin capillary bridge leading to the reference electrode is mounted near the center of cathode to within one millimeter from the side of the cathode. the opening of the capillary tube near the cathode is equal to one millimeter in diameter the apparatus shown in figure (3) was used in the polarization technique. [cornet and kappsser, 1969 and harvey and robert, 1988]. after preparing the seawater (3.5% w/v nacl solution), and construct the electrochemical cell with desired variable of temperature and velocity, the circuit is switched on and the voltage of power supply is stabilized on 3.0 v. changing the current by altering the resistance of the circuit, where at each setting of the resistance, two parameters are recorded (potential and cathodic current) by voltmeter and ammeter respectively. i.e. to measure the cathodic portion of the polarization curve. two minutes at least were are allowed in order to record the steady state values of the polarization process. after reaching ecorr (steady state corrosion potential) of the steel specimen used, the run was ended by switched off the circuit and electrochemical cell is emptied from used seawater. the system is then washed with distilled water to ensure that there is no electrolyte left in the system. the above procedure is repeated exactly for other conditions of temperature and velocity. each test was made twice and if reproducibility was in doubt a third was carried out. khalid w. hameed al-khwarizmi engineering journal, vol. 5, no. 1, pp 20-32 (2009) 24 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 0 5 10 15 20 25 30 35 40 45 50 temperature ( o c) z in c c o n s u m p t io n ( m g / c m 2 . h r ) flowrate 5 l/hr flowrate 300 l/hr flowrate 600 l/hr flowrate 900 l/hr temperature oc flowrate 5 l/h flowrate 300 l/h flowrate 600 l/h flowrate 900 l/h fig.4. temperature effect on zinc consumption rate with variable flow rate. 3. results and discussion i. sacrificial anode cathodic protection system: zinc consumption rate: before calculation of mass transfer coefficient, kd, it must measure the zinc consumption rate in order to show variables effect on corrosion, where kd is an indication to reaction rate (corrosion rate). it can be seen from the figure (4) that the zinc consumption rate increases with increasing temperature and flow rate of seawater. it can explain that as follows: (i) temperature effect (1) a temperature increases usually increases the reaction rate which is the corrosion rate and according to the freundlich equation [shrier (2), 2000]: n o2 ck rate corrosion …(6) where k is the rate constant of reaction, co2 is concentration of oxygen and n is order of reaction. the rate constant, k, varying with temperature according to arrhenius equation [shrier (2), 2000]: rt e oekk   …(7) where ko is constant, e is activation energy, r is universal constant and t is temperature. then from equation (7) indicates that the k is increased with increasing temperature and then the corrosion rate which is lead to increasing the of zinc dissolution. (2) increasing seawater temperature leads to decreasing seawater viscosity with a consequent increase in oxygen diffusivity according to stockes-einstein equation [cussler, 1984 and konsowa and el-shazly, 2002]: constant t d … (8) where μ is seawater viscosity and d is the diffusivity of the dissolved oxygen. as a result of increasing the diffusivity of dissolved oxygen, the rate of mass transfer of dissolved oxygen to the cathodic surface increases according to the following equation [konsowa and el-shazly, 2002]: 22 o d od c d ckj   … (9) with a consequence increase in the rate of zinc dissolution. where j is mole flux of oxygen. (3) the decrease in the seawater viscosity with increasing temperature improve the seawater conductivity with a consequent increase in corrosion current and the rate of corrosion. (4) on the other hand, increase of temperature reduce the solubility of dissolved oxygen with a subsequent decrease in the rate of oxygen diffusion to the cathode surface and the rate of corrosion. it seems that within the present range of temperature effects 1, 2, and 3 are predominating. (ii) flow rate effect: increase zinc consumption rate with increasing flow rate is attributed to the decrease in the thickness of hydrodynamic boundary layer and diffusion layer across which dissolved oxygen diffuses to the tube wall of steel with consequent increase in the rate of oxygen diffusion which is given by equation (9). then the surface film resistance almost vanishes, oxygen depolarization, the products of corrosion and protective film are continuously swept away and continuous corrosion occurs. the flow rate of seawater may also used erosion which combined with electrochemical attack. khalid w. hameed al-khwarizmi engineering journal, vol. 5, no. 1, pp 20-32 (2009) 25 0 0.5 1 1.5 2 2.5 4.5 0 100 200 300 400 500 600 700 800 900 1000 flow rate lit/hr 3 3.5 4 re 0 2000 4000 6000 8000 10000 12000 14000 16000 18000 fig. 5. effect of flow rate (reynold’ s number) on kd with different temperature. temp = 0 o c temp = 15 o c temp = 30 o c temp = 45 o c mass transfer coefficient: the mass transfer coefficient can be expressed in terms of the dimensionless reynolds (re), schmidt (sc) and sherwood (sh) numbers. these numbers are defined by [coulson and richardson, vol. 1 & 2, 2002]:   eud re …(10) d sc    …(11) d dk sh ed …(12) where ρ is density, u is velocity de is equivalent inner tube (based on cross section area of zinc exist in the inner tube], μ is dynamic viscosity d is diffusivity and kd is mass transfer coefficient. for single phase flow in a straight pipe, the correlation of berger and hau (1997) and anederko et al. (2001) can b used: 33.086.0re0165.0 scsh  …(13) the physical properties of seawater at ph = 7 are explained in table (3). table 3, physical properties of seawater at ph = 7 variable temperature o c 0 15 30 45 ρ (kg/m 3 ) 1005.5 1003.9 999.7 995.8 μ (pa.s) 2×10-3 1.3×10-3 0.91×10-3 0.72×10-3 d (cm 2 /s) 1.67×10-5 1.8×10-5 1.95×10-5 2.1×10-5 where ρ is practically measured μ is from coast (1999) and d is from harvey and robert, (1988). to estimate kd e.g. at 15 o c, 300 lit/hr flow rate and de = 2.533 cm the velocity u is 16.5 cm/s. equation (10) gives that re is 3227, from equation (11) sc is 719, from equation (13) sh is 151 and then from equation (12) kd is 10.73×10 -6 m/s. figure (5) shows that the effect of flow rate (i.e. velocity or re) on kd with different temperature, where kd increases with increasing flow rate and temperature according to figure (4). ii. impressed current system: polarization: the characteristic of cathodic polarization curves with variation of temperature and angular velocity have been illustrated in figures (7) to (26). these polarization curves provide information about effects of changes in potential on the corrosion of the cathode as current density (current per unit area). since the electrolyte is seawater (saltwater), the concentration polarization type is predominant [ailor, 1971 and fontana and green, 1984]. from polarization curves, it can be determined practically the free corrosion potential, ecorr and limiting current density, il. where ecorr is determined when the potential becomes approximately constant with decreasing current. the limiting current plateau is not well defined, thus the method given by gabe and makanjoula (1986) will be adopted to fined il values: 2 21 ii il   … (14) where i1 and i2 are the current associated with e1 and e2 respectively as shown in figure (6). from figure (7) to (26) one can see that ecorr is more negative with increasing temperature and with decreasing velocity. while il increases with increasing temperature and velocity. il = icorr is indication for corrosion rate, where the high value khalid w. hameed al-khwarizmi engineering journal, vol. 5, no. 1, pp 20-32 (2009) 26 of il means the high corrosion and vise versa. so the interpretation of increasing il with increasing temperature and velocity are as mentioned in sacrificial anode system. for more explicit and simplicity il were calculated from figures (7 – 26) using equation (14) and figure (6) and plotting the results in figure (27) with variables. -2000 -1800 -1600 -1400 -1200 -1000 -800 -600 -400 -200 0 1 10 100 1000 10000 e ( m v ) /s c e fig.10. cathodic polarization curve at 45 o c and 0 rpm. i (μa/m2) current density, μa/cm 2 potential, mv e1 e2 i1 i2 fig.6. calculate the limiting current density by gabe and makanjoula method. -2000 -1800 -1600 -1400 -1200 -1000 -800 -600 -400 -200 0 1 10 100 1000 10000 e ( m v ) /s c e fig.7. cathodic polarization curve at 0 o c and 0 rpm. i (μa/m2) -2000 -1800 -1600 -1400 -1200 -1000 -800 -600 -400 -200 0 1 10 100 1000 10000 e ( m v ) /s c e i (μa/m2) fig.8. cathodic polarization curve at 15 o c and 0 rpm. -2000 -1800 -1600 -1400 -1200 -1000 -800 -600 -400 -200 0 1 10 100 1000 10000 e ( m v ) /s c e fig.9. cathodic polarization curve at 30 o c and 0 rpm. i (μa/m2) khalid w. hameed al-khwarizmi engineering journal, vol. 5, no. 1, pp 20-32 (2009) 27 -2000 -1800 -1600 -1400 -1200 -1000 -800 -600 -400 -200 0 1 10 100 1000 10000 e ( m v )/ s c e fig.15. cathodic polarization curve at 0 o c and 200 rpm. i (μa/m2) -2000 -1800 -1600 -1400 -1200 -1000 -800 -600 -400 -200 0 1 10 100 1000 10000 e ( m v ) / s c e fig.12. cathodic polarization curve at 15 o c and 100 rpm. i (μa/m2) -2000 -1800 -1600 -1400 -1200 -1000 -800 -600 -400 -200 0 1 10 100 1000 10000 e ( m v )/ s c e fig.16. cathodic polarization curve at 15 o c and 200 rpm. i (μa/m2) -2000 -1800 -1600 -1400 -1200 -1000 -800 -600 -400 -200 0 1 10 100 1000 10000 e ( m v )/ s c e fig.13. cathodic polarization curve at 30 o c and 100 rpm. i (μa/m2) -2000 -1800 -1600 -1400 -1200 -1000 -800 -600 -400 -200 0 1 10 100 1000 10000 e ( m v ) / s c e fig.14. cathodic polarization curve at 45 o c and 100 rpm. i (μa/m2) fig.11. cathodic polarization curve at 0 o c and 100 rpm. -2000 -1800 -1600 -1400 -1200 -1000 -800 -600 -400 -200 0 1 10 100 1000 10000 e ( m v ) /s c e i (μa/m2) khalid w. hameed al-khwarizmi engineering journal, vol. 5, no. 1, pp 20-32 (2009) 28 -2000 -1800 -1600 -1400 -1200 -1000 -800 -600 -400 -200 0 1 10 100 1000 10000 e ( m v ) / s c e fig.18. cathodic polarization curve at 45 o c and 200 rpm. i (μa/m2) -2000 -1800 -1600 -1400 -1200 -1000 -800 -600 -400 -200 0 1 10 100 1000 10000 e ( m v ) / s c e fig.21. cathodic polarization curve at 30 o c and 300 rpm. i (μa/m2) -2000 -1800 -1600 -1400 -1200 -1000 -800 -600 -400 -200 0 1 10 100 1000 10000 e ( m v ) / s c e fig.19. cathodic polarization curve at 0 o c and 300 rpm. i (μa/m2) -2000 -1800 -1600 -1400 -1200 -1000 -800 -600 -400 -200 0 1 10 100 1000 10000 e ( m v ) / s c e fig.22. cathodic polarization curve at 45 o c and 300 rpm. i (μa/m2) -2000 -1800 -1600 -1400 -1200 -1000 -800 -600 -400 -200 0 1 10 100 1000 10000 e ( m v ) / s c e fig.17. cathodic polarization curve at 30 o c and 200 rpm. i (μa/m2) -2000 -1800 -1600 -1400 -1200 -1000 -800 -600 -400 -200 0 1 10 100 1000 10000 e ( m v ) / s c e fig.20. cathodic polarization curve at 15 o c and 300 rpm. i (μa/m2) khalid w. hameed al-khwarizmi engineering journal, vol. 5, no. 1, pp 20-32 (2009) 29 -2000 -1800 -1600 -1400 -1200 -1000 -800 -600 -400 -200 0 1 10 100 1000 10000 e ( m v ) / s c e fig.25. cathodic polarization curve at 30 o c and 400 rpm. i (μa/m2) -2000 -1800 -1600 -1400 -1200 -1000 -800 -600 -400 -200 0 1 10 100 1000 10000 e ( m v ) / s c e fig.23. cathodic polarization curve at 0 o c and 400 rpm. i (μa/m2) -2000 -1800 -1600 -1400 -1200 -1000 -800 -600 -400 -200 0 1 10 100 1000 10000 e ( m v ) / s c e fig.26. cathodic polarization curve at 45 o c and 400 rpm. i (μa/m2) -2000 -1800 -1600 -1400 -1200 -1000 -800 -600 -400 -200 0 1 10 100 1000 10000 e ( m v ) / s c e fig.24. cathodic polarization curve at 15 o c and 400 rpm. i (μa/m2) 0 50 100 150 200 250 300 0 50 100 150 200 250 300 350 400 450 i l ( m a /c m 2 ) t = 0oc t = 15oc t = 30oc t = 45oc fig.27. variation of practical limiting current density with flow rate at different temperature. t = 0 c o t = 15 c o t = 30 c o t = 45 c o flow rate (lit/hr) khalid w. hameed al-khwarizmi engineering journal, vol. 5, no. 1, pp 20-32 (2009) 30 0 5 10 15 20 25 30 35 40 0 50 100 150 200 250 300 350 400 450 k d ( m /s ) x 1 0 6 series1 series2 series3 series4 0 2000 4000 6000 8000 10000 12000 14000 16000 18000 0 10 20 30 40 50 60 0 50 100 150 200 250 300 350 400 450 k d ( m /s ) x 1 0 6 series1 series2 series3 series4 t = 0 c o t = 15 c o t = 30 c o t = 45 c o rotating velocity, ω, rpm fig.29. variation of mass transfer coefficient theoretically with re at different temperature. re mass transfer coefficient: when cathodic current is limited by oxygen reduction reaction (as in equation 15) and when oxygen diffusion through a fluid boundary layer limits the supply of oxygen at the specimen surface for a rotating cylinder, equation (16) is applied to calculate mass transfer coefficient, kd [shrier (1), 2000 and silverman, 2004].  oheoho 442 22 …(15) b l d zfc i k  …(16) it can be seen from equation (16) that that the parameters which can be influence on kd are il and cb . il was estimated from figures (7 – 26) by using the method in figure (6) and equation (14). figure (28) shows that the variation of kd with flow rate or reynolds number at different temperature. limiting current density, il, can be estimated theoretically from the following equation [eisenberg et al., 1954 and harvey and robert, 1988]: 644.03.0re0791.0  scuzfci bl …(17) so from equations (16) and (17) the kd is estimated as: kd = 0.0791 u re -0..3 sc -0.664 …(18) where u is the tangential velocity of specimen surface (π×d×rpm/60), d is the diameter of specimen cylinder (2.33 cm), z is the number of electrons in reduction reaction of oxygen (equation (15)) which is equal to 4 eq/mol, cb is the concentration of oxygen in bulk [shrier,1, 2000] and f is faraday's number (96494 c/eq). reynolds and schmidt numbers are estimted as in equations (10) and (11), respectively. figure (29) shows mass transfer coefficient, kd, which was estimated theoretically versus reynolds number at different temperature. it can be noted that kd increases with re (or rotation velocity, ω) and with increasing t, that ’ s mean increasing corrosion rate with increasing ω and t. it can be seen that there is a difference between figures (28) and (29) because kd in figure (29) was estimated from equation (18) where the velocity is affected mainly on kd where if the velocity is zero the kd will be zero while practically kd has some value at zero velocity. so the range of rotation velocity in figure (29) was taken from 50 to 400 rpm to avoid zero value of kd. fig.28. variation of mass transfer coefficient practically with re at different temperature. rotating velocity, ω, rpm re t = 0 c o t = 15 c o t = 30 c o t = 45 c o khalid w. hameed al-khwarizmi engineering journal, vol. 5, no. 1, pp 20-32 (2009) 31 4. conclusions 1. in the sacrificial anode cathodic protection (sacp) method the mass transfer coefficient kd increases with increasing volumetric flow rate or reynolds number and with increasing temperature that ’ s mean the corrosion rate increases with two variables above. 2. in the impressed current cathodic protection (iccp) method, kd increases with increasing rotation velocity or reynolds number and with temperature. 3. there is some a difference between the practical results and theoretical results of the kd in the iccp. 5. references [1] ailor, w. h. (1971), "handbook on corrosion testing and evaluation", john wiley and sons inc. [2] anderko, a., mckenzie, p. and young, r. d. (2001), "computation of rates of general corrosion using electrochemical and thermodynamic modes corrosion". [3] berger, f. p., hau, k-f. f. l. (1977), int. j. heat mass transfer, 20, pp 1185-1194. [4] champion, f. a. (1964), "corrosion testing procedures", 2 nd edition. [5] coast guard u.s. (1999), chemical hazardous response information system (chris), selected properties of fresh water, seawater, ice and air. [6] cornet i. and kappesser, r. (1969), "cathodic protection of a rotating cylinder", trans. [7] instn. chem. engrs., 47. [8] cottis, r. a. (2002), "electrochemical kinetics and thermodynamics". [9] coulson, j. m. and richardson, j. f. "chemical engineering", vol. 1 (1999) and vol. 2 (2002). [10] cussler, e. l. (1984), "mass transfer in fluid systems", cambridge university press, cambridge, uk. [11] eisenberg, m., toblas, c. w. and wilke, r. c. (1954), j. electrochemical society, 101 (6), pp 306-319. [12] fontana, m. g. and greene, n. d. (1984), "corrosion engineering", 2nd edition, mcgraw-hill. [13] gabe, d. r. and makanjoula, p. a. (1986), efcf publication series no. 15, "electrochemical engineering", aiche symposium series, (98), p. 309. [14] hanson, h. r. (2000), "offshore cathodic protection guidelines: relevance of short term laboratory testing". (internet site: www.corrosionsource.com). [15] harvey, p. h. and robert j. g. (1988), paper no. 38, corrosion 88, march 21-25. [16] konsowa, a. h. and el-shazly, a. a. (2002), elsevier, desalination, 153, pp 223226. [17] roberge, r. p. (1999), "handbook of corrosion engineering". [18] roberge, r. p. (2004), "electrochemical kinetics principles nearest diffusion layer ". (internet site: www.corrosiondoctor.org) [19] scully, j. c. (1975), "the fundamental of corrosion", 2 nd edition. [20] shrier (1), l. l. (1976), "corrosion 1, metal/environment reactions", newnesbutterworth. [21] shrier (1), l. l. (2000), "corrosion 1, metal/environment reactions", newnesbutterworth. [22] shrier (2), l. l. (2000), "corrosion 2, corrosion control", 3rd edition, newnesbutterworth. [23] trethewey, k. r. and chamberlain, j. (1996), "corrosion for scientist and engineering", 2nd edition. [24] uhlig, h. h. (1971), "corrosion and corrosion control, an introduction to corrosion science and engineering", johnwiley and sons. http://www.corrosionsource.com/ http://www.corrosiondoctor.org/ 200 )32-20، صفحت 1، انعذد 5مجهت انخىارزمي انهىذسيت انمجهذ خانذ ونيذ حميذ 9) 32 معامم اوتقال انمادة خالل انحمايت انكاثىديت نحذيذ واطئ انكاربىن في مياي انبحر خانذ ونيذ حميذ. د * ، أويس عبذ هللا كاظم ** ، أميم محمذ رحمه * قسى انهُذسح انكيًيائيح األحيائيح / جايعح تغذاد / كهيح انهُذسح انخىارزيي * جايعح ديانً/ كهيح انهُذسح ** انخالصت 3.5%)يياِ انثحر انًرعادل خالل انحًايح انكاثىديح نحذيذ واطئ انكارتىٌ في , kd, انهذف يٍ انثحث هى حساب يعايم اَرقال انًادج nacl ٌذى اسرخذاو طريقريٍ يٍ انحًايح انكاثىديح. (7= حايضيح دانححجى في انًاء انًقطر و \وز : ًً يياِ انثحر تأسرخذاو قطة انخارصيٍ كأَىد ذضحيح عُذ انًرغيراخ انحذيذ انحًايح انكاثىديح تطريقح أَىد انرضحيح ألَثىب: االونً حايالً 45 – 0)درجح انحرارج تًذي : االذيح ِ يسداد تسيادج درجح انحرارج kdنقذ وجذ أٌ . (ساعح\ نرر900 – 5)ويعذل جرياٌ حجًي تًذي (و kd .(0.24×10حيث ذراوحد قيًح , او رقى ريُىنذ وزيادج يعذل انجرياٌ انحجًي -6 – 41.6×10 -6 m/s) درجح انحرارج : انحًايح انكاثىديح تطريقح انريارانًسهظ ألسطىاَح حذيذيح يذورج عًىدياً في يياِ انثحر انًرعادل عُذ انًرغيراخ االذيح:انثاَيح 45 – 0)تًذي ِ يسداد تسيادج درجح انحرارج وزيادج سرعح ذذوير االسطىاَح kdنقذ وجذ أٌ . (دقيقح\ دورج400 – 0)وسرعح ذذوير تًذي (و kd .(7.25×10حيث ذراوحد قيًح , او رقى ريُىنذ -6 – 36.82×10 -6 m/s) al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 112 (2015) intelligent h2/h∞ robust control of an active magnetic bearings system safanah m.raafat * rini akmeliawati ** *department of control and system engineering/ university of technology **department of mechatronics engineering/ intelligent mechatronics systems research unit/ international islamic university malaysia iium/ malaysia *email: safanamr@gmail.com **email: rakmelia@iium.edu.my (received 4 march 2014; accepted 18 january 2015) abstract robust controller design requires a proper definition of uncertainty bounds. these uncertainty bounds are commonly selected randomly and conservatively for certain stability, without regard for controller performance. this issue becomes critically important for multivariable systems with high nonlinearities, as in active magnetic bearings (amb) system. flexibility and advanced learning abilities of intelligent techniques make them appealing for uncertainty estimation. the aim of this paper is to describe the development of robust h2/h∞ controller for amb based on intelligent estimation of uncertainty bounds using adaptive neuro fuzzy inference system (anfis). simulation results reveal that the robust controller design objectives of wide bandwidth and improved performance are satisfied for a wide range of frequency variations. it can be concluded that the intelligent uncertainty weighting functions can precisely compensate for the effects of modelling errors and nonlinearities in the system. keywords: active magnetic bearings (amb) , adaptive neuro fuzzy inference system (anfis), h2/h∞ robust controller, modelling errors, uncertainty bounds. 1. introduction recently research involving the combination of hard and soft computing has developed with the aim of complementing these sets [1]. realworld problems can be solved in more innovative ways by combining the attractive features of both computing methods. the goal of this paper is to show such combination applied to an industrial process. this research will show that the soft computing aspects of adaptive neuro fuzzy inference system can be used together with the hard computing features of robust h∞ control to accomplish valuable results in an easier, more efficient fashion. robust control is a hard computing design methodology dedicated to provide assured stability and performance for uncertain dynamic systems. robust control synthesis needs a precise mathematical model of the plant dynamics and bounds on the uncertainty related to that model. such uncertainties may result from parameter variations, under-modeled dynamics, or process disturbances [2]. by specifying a nominal model and a ―hard bound‖ on the uncertainty related to that model, robust control aims to guarantee robust stability for the actual system, which must lie within the set defined by the model plus the uncertainty bound. for robust control synthesis it is accustomed to choose uncertainty bounds (uncertainty weighting functions) that are somewhat random and exceedingly conservative to guarantee stability, usually at the expense of performance. in order to overcome this drawback, intelligent methods are developed to design the unstructured uncertainty (or the modelling error) weighting function for h∞ robust control synthesize. reliable and efficient tool are obtained as in [3],[4]. as a combination of neural networks (nns) and fuzzy logic, neural-fuzzy systems can make good use of both sensory numerical data and mailto:safanamr@gmail.com mailto:rakmelia@iium.edu.my safanah m.raafat al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 111 (2015) 2 expert linguistic information; system performance tuning is flexible as the number of membership functions and training epoch numbers can be altered easily [5]. therefore, the anfis technique is used in [6] to estimate the uncertainty bounds for robust motion controlled system. then the applied anfis estimation is further improved in [7] to estimate uncertainties in more difficult situations. the frequency ranges of the uncertainties in the model are precisely located, and the synthesized controlled system becomes insensitive to them while guaranteeing a specified performance and larger stability margin of robust controllers, as measured by the v-gap metric. the design application to an uncertain mimo system model of an active magnetic bearing (amb) system [8] has been extended in this paper to include the theoretical formulation of the control problem and the estimation of uncertainties using different ranges of frequencies. precise quantification of uncertainty due to ‗mainly‘ the modelling errors has been achieved. robustness against changes in operating frequencies has been observed. this paper is organized as follows: section 2 describes the dynamics of the amb system, section 3 introduces a brief description of robust identification, section 4 presents adaptive neuro fuzzy inference system (anfis) for uncertainty estimation, section 5 defines the applied h2/h∞ robust control, section 6 presents some simulation results and discussion and finally, in section 7 conclusions will be drawn. 2. dynamic amb system model amb is a collection of electromagnets producing a magnetic field to support a rotating iron shaft without any physical contact. ambs are open loop unstable and the stabilization of the system can only be done by feedback control. in addition, their complex structure requires powerful control system design approaches for robust stability and robust performance. the rigid body diagram for an amb is shown in figure. 1. the steel rotor has a mass of 1.549 kg and a length of 0.457 m, the two steel disks are positioned to modify the modal characteristics at high speeds. two radial ambs are located at the ends of the rotor, orthogonally aligned in the x and y directions, together with two orthogonal pairs of sensors to measure rotor displacements from the bearing line of centre. these radial ambs comprise a four input (bearing currents) and four output (displacements) dynamic system. a linearized system dynamics obtained from a lagrangian analysis of an amb can be expressed using a state vector composed of the rotor displacement and their time derivatives [4]: buaxx  …(1) cxy  …(2) where,        m m z z x  ,          bbsb i gmkm a 11 0 ,         ib km b 1 0 , t        0 i c , zfb mttm 1 , , zfb gttg 1 ,              b a b a m y y x x z ,                cs s cs s s kk k kk k 000 000 000 000 k ,              i i i i i k k k k 000 000 000 000 k ,                ba ba f ll ll 00 1100 00 0001 t ,                 ba ab ab ba z ll ll ll ll 00 00 0011 00 1 t ,                y y i m i m 000 000 000 000 m ,               000 0000 000 0000 z z i i g , with system parameters m=1.549kg, 2210392 m.kg.ii yx  , 2410 m.kgi z  , m.la 1530 , m.lb 1700 , ω = 627.0rad/sec., m/n.ks 310596  , a/n.ki 929 ,and m/n.kc 31062  . the resulting continuoustime model is unstable, with eigenvalues [13] ...(3) safanah m.raafat al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 111 (2015) 3 fig. 1. generalized rigid rotor supported by two radial bearings [4]. 3. robust identification in standard identification problems, the perturbations potentially arise from two different sources as illustrated in table 1. in most practical situations, the model error is considered, especially when the order of the nominal model must be small, as usually required in robust design techniques. moreover, while prior information on measurement noise can be obtained, similar hypothesis on unmodeled dynamics is less realistic. three main approaches for robust identification have been addressed in literature: 1. stochastic embedding (se), which can be described as: ―a frequency domain method which assumes that unmodeled dynamics can be represented adequately by a nonstationary stochastic process whose variance increases with frequency‖ [9]. 2. set membership identification (smi), provides efficient algorithms for estimating the set of feasible models, compatible with the available data and the ubb error assumption [10]. table 1, sources of perturbations in a standard identification problem. 3. model error modelling (mem), is an effective robust parametric identification approach to estimate the model uncertainty bound. mem technique employs standard prediction error methods to identify an error model from input– output time domain data. the un-modelled dynamics can be estimated by looking at that part of identification of residuals that originates from the input, [11], and [12]. in addition, the uncertainty can be estimated regardless of the order of the nominal model. for these appealing features, this method is implemented in this work. mem can be briefly described as follows: if assuming that (u, yo) is the measurement data set, and gn is the system nominal model estimated with (u, yo), then the model error modelling method can be summarized as follows: i. first, compute the residual: ugy no  …(4) ii. consider the ―error‖ system with input u and output ε, and identify the model-error model ge for this system. this model provides the estimation of the undermodelling error. iii. from the nominal model and the model error, the uncertainty region can be constructed by adding the model error to the nominal model in the frequency domain. this gives a region where true system is supposed to be found. iv. model validation: the nominal model is not falsified if and only if it lies inside its own uncertainty region (as delivered in step iii). nevertheless, the drawback of this technique is that it leads to conservative uncertainty sets because it is based on the worst case assumptions [2], [13], and [14]. mem has been modified in [4] to a non-parametric regression problem in the frequency domain using feed forward neural networks. the identification reduces the conservativeness of the estimated uncertainty bounds with a suitable confidence region. in this work, it will be further modified using anfis to simplify the computational efforts and reduce the calculating time, making real time implementation more suitable. 4. adaptive neuro fuzzy inference system (anfis) for uncertainty estimation anfis as created by [15] may be attributed to have generated a new paradigm in fuzzy-neural computation which strongly supports zadeh‘s soft-computing ideas [16]. the use of the anfis is characterized by [14]: sources characteristics variance error measurement noises generally uncorrelated with the input signal (when the data is collected in open loop). bias the effect of un-modeled dynamics strongly depends on the estimated nominal model structure and on the input signal used in the identification experiment. safanah m.raafat al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 111 (2015) 4  the fuzzy logic component gives the algorithm a degree of robustness and combines it with the learning abilities of the neural network.  the neural network aspects of the anfis allows for multiple attempts of generating the rule base and membership functions. this provides a detection scheme that has a low error rate in predicting the output, with the fewest number of rules and membership functions to keep computation times to a minimum, the consequent parameters thus identified are optimal under the condition that the premise parameters are fixed.  the hybrid approach that combines neural network and fuzzy logic is much faster than the strict gradient descent. one of the most important and effective areas of applications of anfis is modelling, estimation and prediction of systems with uncertainties. some of these applications can be found in [17][24]. the common advantages between these works can be summarized as follows:  there is the ability to converge much faster that the back-propagation ann; the number of epochs is several orders of magnitude less than the one needed for training of the corresponding back-propagation ann.  the ability to adapt to environmental changes.  the anfis is also repeatable over time, with minor recalibration. 4.1. anfis structure figure 2 shows the equivalent type-3 takagi and sugeno (t-s) fuzzy if-then rules used for anfis architecture [15], where the system has two inputs x and y. the output of each rule is a linear combination of input variables plus a constant term, and the final output is the weighted average of each rule‘s output. the fuzzy if-then rule set, in which the outputs are linear combinations of their inputs, is:  rule 1: if x is a1 and y is b1 then f1=p1x+q1y+r1  rule 2: if x is a2 and y is b2 then f2=p2x+q2y+r2 where, a‘s and b‘s are particular fuzzy subsets defined by nonlinear coefficient, namely premise parameters, while p‘s, q‘s and r‘s are linear coefficients determining the output of each applied fuzzy rule, usually known as consequent parameters. figure 3 shows the basic architecture of adaptive neuro-fuzzy inference system (anfis). in general, anfis has input and output layers, and three hidden layers that represent the membership functions and the fuzzy rules [15]. layer 1 is the input layer. it consists of adaptive nodes, which generate membership grades of linguistic labels based upon premise signal that use the generalized bell membership function. layer 2 is the input membership or fuzzification layer with fixed nodes designated π that represents the firing strength of each rule. the output of each node is the fuzzy and of all the input signals. layer 3 is the fuzzy rule layer. the outputs of layer 3 are the normalized firing strengths. each node is a fixed rule labelled n. the adaptive nodes in layer 4 calculate the rule outputs based upon consequent parameters. the single node in layer 5, labelled σ, calculates the overall anfis output from the sum of the node inputs. starting from initial model and following modelling optimization procedure, as described in [24], the optimal number of fuzzy rules is determined. accordingly, anfis of four rules is found to be most suitable for this application. fig. 2. t-s fuzzy reasoning [15]. a1 a2 b1 b2 π π n n ∑ 1w 2w 11 fw 22 fw 1w 2w y   x layer 1 layer 2 layer 3 layer 5layer 4 f y y x x fig. 3. architecture of an anfis equivalent to a first-order sugeno fuzzy model with two inputs and two rules [15]. 4.2. hybrid learning algorithm from the anfis system shown in figure 3 with fixed premise parameters values, the overall output can be expressed as a linear consequent of the consequent parameters. the output f in figure 3 can be rewritten as: f2=p2x+q2y+r2 f1=p1x+q1y+r1 safanah m.raafat al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 111 (2015) 5    22221111 2 21 2 1 21 1 21 2211 ryqxpwryqxpwf f ww w f ww w ww fwfw f         …(5) which is linear in the consequent parameters p1, q1, r1, p2, q2, r2. the training algorithm of anfis takes the initial fuzzy model and tunes it by means of a hybrid technique combining gradient descent back-propagation in the backward pass and mean least-squares optimization algorithms in the forward pass, as shown in figure 4. at each epoch, an error measure defined as the sum of the squared difference between actual and desired output is reduced. training stops when either the predefined epoch number or error rate is obtained. the gradient descent algorithm is implemented to tune the nonlinear premise parameters, while the basic function of the mean least-squares is to optimize or adjust the linear consequent parameters. 4.3. implementation of anfis for identification of uncertainty bounds the main purpose of the intelligent uncertainty identification is to estimate the upper magnitude bound of the model error frequency response function ge(jω)[4],[6]: )j(u )j(e )j(g)j(g)j(g nre     …(6) where gr(jω) is the measured frequency response function of the actual system, gn(jω) is the frequency response function of the nominal linear model of the system, e(jω) is the fast fourier transform (fft) of prediction error e(t) and u(jω) is the fft of u(t). note that plant uncertainties and non-deterministic effects give rise to frequency dependent intervals associated with |ge(jω)|. figure 5 shows non parametric estimation of the model error frequency response function |ge(jω)| using sampled input-output data and a simple anfis structure as described in section 4.1 enhanced by feedback signal. the anfis provides an estimate of the model error magnitude  f,jgu  that is conditioned on the input frequency ω and the anfis output function f. the feedback signal helps to further eliminate the error between the actual model error frequency response |ge(jω)| and the intelligently estimated uncertainty bound  f,jgu  . using this approach, the corresponding intelligent estimation of uncertainty bound can be formulated as:      kkudke kkudkeku jejgfw jejgfwfjg   ),(),( ),(),(, 122 111    …(7) )nn,...,k(k 1 where f1 and f2 are selected as second order nonlinear function models, nn is the number of data samples and eud is a prediction error: )]f,j(g)j(g[)k(e kukeud   …(8)  f,jgu  (12) is trained to minimize a cost function of prediction errors by automatically adjusting the anfis function f. the goal is to enhance the search for less conservative uncertainty bound through iterative minimization procedure until the stopping criteria is met  |e|)e(j udud …(9) where |eud| is the absolute value of the prediction error and δ is a pre-specified very small numerical value, e.g. less than 10 -3 . premise parameters leastsquares regression consequent parameters p,q,r mean leastsquares gradient descent update forward pass backward pass fig. 4. anfis learning using hybrid technique. |ge(jω)| anfis |e(jω)| |u(jω)| |gu(jω)| e(t) u(t) frequency (jω) time to frequency conversion time to frequency conversion / generate a fis structure eud fig. 5. intelligent estimation of the uncertainty weighting function, using anfis. safanah m.raafat al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 111 (2015) 6 theorem 1: let )( min min kudud ee    ; ),...,1( nnkk  and )( minmin uduu egg  for a given model error estimation. min ug satisfies certain stopping criteria. hence, the intelligent uncertainty weighting function wa obtained from the intelligent estimated uncertainty bounds ug is: |g|w ua min  …(10) proof: given the measured controlled signal, u, and estimated error model, ε, required to develop the upper magnitude bound of the model-error function as defined in equation (6), and considering anfis based intelligent estimation of uncertainty as given in equation (7). if equation (8) is minimized within a given number of iterations while satisfying equation (9), then the statement of equation (10) is true for ωk (k=1,…,nn). the training of anfis should cover the frequency response function magnitude of ge. in order to illustrate this issue, the anfis should be trained to identify the model error magnitude associated with the linear model of the system over a suitable frequency range, e.g. within the system‘s nyquist frequency. the anfis within this scheme can efficiently estimate nonconservative uncertainty bound using large amplitude signals over different range of frequencies within short time of calculations and considerably simplified computation [7]. for a mimo system, it is necessary to estimate as many uncertainty weighting functions as the number of measured variables. consequently, the resulted weighting functions will be combined in the following uncertainty weighting matrix and used to synthesize the robust controller, as will be described next.              4 3 2 1 000 000 000 000 a a a a a w w w w w …(11) 5. simplified h2/h∞ robust control the generalized plant considered for a system is: ubbaxx i 21   …(12) udxcz 121  …(13) idxcy 212  ...(14) where ωi is the exogenous inputs external to the closed-loop system such as measurement noise, u is the control input vector, y is the measured output vector, and z is the regulated output vector. then the plant‘s transfer matrix can be partitioned as follows:                   2221 1211 212 121 21 0 0 pp pp dc dc bba )s(p …(15) such that )s(u)s(p)s()s(p)s(z i 1211   …(16) and )s(u)s(p)s()s(p)s(y i 2221   …(17) with a proper rational controller k(s), the control is given by y)s(ku  …(18) substituting equation (18) into equation (16) and equation (17), the following relationship is obtained:   )s()s(pz)s(k)s(p)s(p)s(z ii 211211  …(19) where   1 22   )s(k)s(pizi the transfer matrix which is the transfer function from the exogenous input ωi(s) to the regulated output z(s) -can be denoted f(s) for simplicity of notation and can be written as: )s()s(f)s(z i …(20) where  )s(pz)s(k)s(p)s(p)s(f i 211211  the generalized plant model is shown in figure 6, and the linear fractional transformation (lft) of model, is:                n u enee a gii w wgww w )s(p 00 00 …(21) where i is an identity matrix. safanah m.raafat al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 111 (2015) 7 since there are multi objectives that need to be satisfied; robust stability, robust performance, faster tracking and minimized the effects of uncertainties and measurements errors, the robust controller is formulated in this case as a mixed h2/h∞ problem. the prescribed specifications are translated into the following criterion: minimize 22tt mm    …(22) while maintaining the h∞ of the closed loop transfer function t∞ from ωi to z∞ < γ0 and maintaining the h2 of the closed loop transfer function t2 from ωi to z2 < ν0, where αm >0, βm >0, γ0> 0 and ν0 >0 are some prescribed value. moreover, places the closed loop poles in the lmi open left hand plan region. we is selected to adjust the performance and eliminate the steady state error. wu is selected to attenuate the high frequency noises as much as possible [2]. wa is used to shape the closed-loop transfer function at frequencies where uncertainties expected to appear. the intelligent uncertainty weighting function derived directly from the identified anfis uncertainty bound can be used for robust control synthesis of a system. the intelligent weighting function accurately reflects additive uncertainty associated with the nominal model, as illustrated in section 4.3. since the order of the h∞ controller is directly related to the order of this weighting function, it is recommended to substitute a low order transfer function for the anfis uncertainty bound. + wu wa ∆ gn we k z2 u y r z1 e ∆u∆y fig. 6. the entire-connection of the robustlycontrolled system. 6. results and discussion the intelligent approach to estimate uncertainty bound was implemented to adaptively bound modelling uncertainty for robust controller design. as a result, an anfis estimation of uncertainty bounds for an amb system model was developed and implemented to generate uncertainty weighting functions required for robust controller design. then, in order to validate these weighting functions a corresponding robust controller k(s) is designed. the entire connection of figure 6 is used, with suitable selection of we and wu. table 2 summarizes the numerical results of the intelligent estimation and robust controller design of the uncertainty bounds for the amb system. comparison was conducted with intelligent estimation method of intelligent confidence interval network neural network (cin nn) [8] for the purpose of validation; less complicated procedure, and reduced number of calculations are achieved. it is also obvious that the learning time required for anfis is almost ten times faster than the time required for cin, and the number of iteration of anfis is five times less than the number of required iterations for cin, for the same number of training data pairs. since the order of the robust h2/h∞ controller is directly related to the order of the uncertainty weighting function, it is desirable to substitute a low-order transfer function for the anfis bound. matlab‘s fitsys command is applied to construct such a low-order weighting function. figure 7 shows the four anfis estimated uncertainty weighting functions at 83.375 hz. according to the applied method of mem to estimate the upper magnitude bound, these transfer functions can accurately reflect additive uncertainties. table 2, comparison between two intelligently identified uncertainty weighting functions. no. of training data pairs= 1900. learning time (sec.) no. of iteration of training order of wak (k=1,..,4) cin nns 106.2426 100 4 anfis 16.2154 20 3 best objective lmi klmi dimension no. of iteration lmi cin nns 1.998 [4,32] 47 anfis 1.997 [4,28] 44 intelligent robust controller is designed using the dynamic model described by equation (1) based on a nominal rotation speed of 6.0 krpm. the controller integrated the anfis weighting function aw of figure 7, the performance weighting function we and input weighting function wu . table 2 indicates that the lower order of anfiswa results in a lower order safanah m.raafat al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 111 (2015) 8 controller matrix than that developed using cin, indicating a relatively simplified controller. then, another set of experiments is conducted. the purpose is to illustrate the ability of the developed intelligent estimation of uncertainties to follow variations over a wide range of operating speeds. figure (8-a) compares the anfis estimated uncertainty weighting functions wa1 at 83.375 hz (the nominal value), 100 hz and 200 hz. the magnitudes of these uncertainty weighting functions show that as the rotational speed of the system moves away from the nominal speed that is used in the modelling, and clearly, the amount of uncertainty increases. it is clear that these intelligent weighting functions can accurately reflect model uncertainty variations in spite of changes in operating speeds. and according to theorem 1, the intelligently estimated weighting functions are optimized weighting functions. similarly, the weighting functions wa2 , wa3 , and wa4 are changed in accordance with variations of uncertainty bounds as frequency changed. these effects can be observed in figure 8-b,c,d). as a result, the synthesized robust controller using these weighting functions of intelligent aw will be less conservative with high performance quality. meanwhile, the optimization results of the h∞ performance under lmi constraints have been slightly affected by variations as illustrated in table 3. 10 -5 10 -4 10 -3 10 -2 10 -1 10 0 -200 -190 -180 -170 -160 -150 -140 -130 -120 -110 m ag n it u d e (d b ) bode diagram frequency (rad/sec) wa1 wa2 wa3 wa4 fig. 7. the anfis identified weighting function wa for amb model, at 83.375 hz [ 8 ]. 10 -4 10 -2 10 0 -210 -200 -190 -180 -170 -160 -150 -140 -130 -120 -110 m ag n it u d e (d b ) bode diagram frequency (rad/sec) wa1 83.3758hz wa1 100 hz wa1 200 hz (a) 10 -4 10 -3 10 -2 10 -1 -200 -180 -160 -140 -120 -100 m ag ni tu de ( db ) bode diagram frequency (rad/sec) wa2 83.3758 hz wa2 100 hz wa2 200 hz (b) 10 -6 10 -4 10 -2 10 0 -190 -180 -170 -160 -150 -140 -130 -120 -110 m ag ni tu de ( db ) bode diagram frequency (rad/sec) wa3 100 hz wa3 83.3758 hz wa3 200 hz (c) 10 -6 10 -4 10 -2 10 0 -190 -180 -170 -160 -150 -140 -130 -120 -110 -100 -90 m ag ni tu de ( db ) bode diagram frequency (rad/sec) wa4 83.3758 hz wa4 100 hz wa4 200 hz (d) fig. 8. comparison of anfis wa bounds for different operating speeds: (a) wa1, (b) wa2 , (c) wa3 and (d) wa4.. safanah m.raafat al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 111 (2015) 9 table 3, comparison between three intelligently identified uncertainty weighting functions. frequency of estimated wa (hz) learning time (sec.) best objective lmi klmi dimension lmi noi* 83.3758 58.1862 1.998 [4*36] 41 100 57.2815 2.004 [4*36] 51 200 61.4213 1.997 [4*32] 43 *noi :number of iterations. 7. conclusions the objective of this paper has been to develop an intelligent estimation of uncertainty bounds for robust lmi control of amb systems. robust control theory provides systematic representation of uncertainties. however, the selection of suitable weighting functions is a critical requirement for robust stability and performance. anfis in mem framework is developed to estimate least conservative uncertainty weighting function. successful application of the proposed anfis estimation algorithm for mimo systems is accomplished; similar accuracy to neural network estimation is obtained in a shorter learning time and less number of iterations of training. moreover the order of the estimated weighting function is reduced using the developed anfis method. the order of the evaluated lmi robust controller is reduced as well, which is preferred for practical applications. different amount of uncertainties were identified using anfis technique for various frequency operating conditions, resulting in accurate uncertainty weighting functions. the upcoming work is to extend the anfis method for linear parameter varying (lpv) method to maintain the stability and robust performance over wider operating ranges. moreover, online updating of the anfis bounds will be added to effectively adapt to parameter variations. notation k gn,k a generalized stability margin of the stable loop [gn, k] ge model of model error gn model of nominal model gu intelligent uncertainty bound wa additive uncertainty weighting function we performance weighting function wu control weighting function eud prediction error x,y longitudinal displacement of radial active magnetic bearings z axial displacement of thrust active magnetic bearing. m rotor weight ix ,iy polar mass inertia of rotor iz axial mass inertia of rotor ks displacement stiffness ki current stiffness kc coupling stiffness ω nominal rotor speed λ eigenvalues acknowledgements the first author would like to thank the research management center and the faculty of engineering of international islamic university malaysia for the support during her post-doctoral period in 2012. 8. references [1] s.j. ovaska, s.j.ovasaka, h.f. vanlandingham, and a. kamiya. fusion of soft computing and hard computing in industrial applications: an overview. ieee transactions on systems, man, and cyberneticspart c: applications and reviews, 32(2), may 2002. 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(2015) 111، صفحة 2، العذد11دالخىارزمي الهنذسية المجلجلة م سفانة مظهر رافت 11 ركي متين لمنظىمة المحامل المغناطيسية النشطة ∞h2/hمسيطر ** تياملياوكرني ال * سفانة مظهر رافت ونىجيت انجايعت انخكٍ/ قسى هُذست انسيطشة وانُظى* يانيضيا iium / االسالييتانًانيضيت انعانًيتانجايعت/ قسى هُذست انًيكاحشوَكس** safanamr@gmail.com : االنكخشوَي انبشيذ* rakmelia@iium.edu.my: انبشيذ االنكخشوَي** خالصة ال و يخى عادة اخخياس حذود عذو انىثىقيت بشكم عشىائي و يخحفظ نخحقيق االسخقشاسيت . يخطهب حصًيى انًسيطش انًخيٍ حعشيف يُاسب نحذود عذو انىثىقيت عانيت كًا في حانت يُظىيت هزِ انحانت حصبح اشذ صعىبت نًُظىياث يخعذدة انًخغيشاث راث ال خطيت . انًطهىبت و بغط انُظش عٍ جىدة أداء انًسيطش . اٌ انًشوَت انخي حًخاص بها انخقُياث انزكيت و قابهياحها انًخقذيت في انخعهى يجعهها يُاسبت نخطبيقاث اسخُباط انحانت .(amb)النشطة المغناطيسية المحامل بُاءا عهً اسخُباط انحانت انزكي نحذود عذو انىثىقيت النشطة المغناطيسية المحامليخيٍ نًُظىيت ∞h2/hانغشض يٍ هزِ انًقانت هى بُاء يسيطش كشفج َخائج انًحاكاث اٌ اهذاف انًسيطش انًخيٍ بخحقيق حضيت واسعت نهخشدد انفعال و . (anfis)انعصبي انضبابي انًخكيف االستداللباسخخذاو َظاو اٌ دوال عذو انىثىقيت انزكيت حًكٍ يٍ ححذيذ حأثيش أخطاء انًُزجت و عذو انخطيت بذقت َسخُخج و نهزا. بأداء يخيٍ قذ ححققج نًذي واسع يٍ حغيش انخشدداث . عانيت mailto:safanamr@gmail.com*البريد mailto:safanamr@gmail.com*البريد mailto:rakmelia@iium.edu.my <4d6963726f736f667420576f7264202d2037312d3738dfe6cbd120e6dae1ed20e6c3e3edd120cdd3ede4> al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 15, no. 4, december, (2019) p. p. 71-78 evaluation of yogurt production line simulation using arena software kawthar a. mohammed hasan* ali h. kadhum** ameer h. morad*** *, **department of automated manufacturing engineering/ al-khwarizmi engineering college/ university of baghdad/ iraq ***department of information and communication engineering / al-khwarizmi engineering college/ university of baghdad/ iraq *email: kawthar.abd.alhameed@gmail.com **email: kadhumali59@yahoo.com ***email: ameer_morad@yahoo.com (received 24 july 2019; accepted 21 october 2019) https://doi.org/10.22153/kej.2019.10.003 abstract the main purpose of the paper is to identify the controllability of an existing production system; yogurt production line in abu ghraib dairy factory which has several machines of food processing and packing that has been studied. through the starting of analysis, instability in production has been found in the factory. the analysis is built depending on experimental observation and data collection for different processing time of the machines, and statistical analysis has been conducted to model the production system. arena software is applied for simulating and analyzing the current state of the production system, and results are expanded to improve the system production and efficiency. research method is applied to contribute in knowing and expecting the future running of the system to enhance the controllability of the system production and improve the production system and machine efficiency. moreover, build an experimental model in arena in order to simulate the system in term of production and process. first step is to collect the statistical data required for analysis in terms of input and output data for analysis. second, is to track the production problem in term of process bottleneck in order to improve the utilization of the system. third is to validate the model in order to overcome the product demand of the system uncontrollability. through the result analysis of waiting time and production rate, it is clearly shown that system is stable with a need to resetting the capacity as a chance for the improvement, regarding to resources utilization. re-planning resources capacity positively enhances the production and profitability of the system. the validation percent of the experimental results of output products and actual number of products is about 98%. keywords: arena simulation, evaluation of manufacturing system, yogurt production line. 1. introduction simulation is a powerful tool to evaluate and improve of actual production line systems without disturbing its operation by builds a simulation model using computer. running the model for long and short times experiments to tracks if there is any occurrence of problems or bottlenecks during running of the processes. also simulation helps the managers to make proper decision for controllability of product line steps. arena is discrete event simulation and automation software expanded by systems modeling and obtained by rockwell automation in 2000. arena simulation modeling software used to solve several types of problems such as layout problems, analysis of the production line, cycle time. improve the production efficiency. kawthar a. mohammed al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 7178 (2019) 72 production line balance, workers and machine performance. arena software can be used in modeling and simulation of flexible system for electrical machine assembly, m. bruqi et al. [1] used arena to model an electrical machine assembly and they include design, analytical and optimization tasks of complex production systems, computer architecture, and gain good results. w. r. nyembaa and c. mbohwab [2] attempted to develop an effective system for the materials flow of multi product furniture assembling factory through modelling and simulation, also provide the demand at an appropriate time and a minimal cost. r. mathur et al. [3] studied the production of utensils and the impact of the location of the machines in a plant and employee's amenities on the efficiency of the production. also attempted to improve the factory layout through using arena simulation. m. s. eryilmaza et al. [4] studied shoe manufacturing that was analyzed and modeled in arena and specific production policy was implemented and developed for the shoe making company. r. p. nithin et al. [5] studied a manufacturing planning for a pvc sheets of cooling towers and aimed to raise the productivity, the simulation study was determined by arena software and was designed using cad package. lopez et al. [6] conducted in the area of gynecological surgery a time study program, to indicate the current level of capacity and enhance the programming time so as to respond to demand immediately. the system was analyzed by waiting lines and used arena simulation to estimate suggestions for enhancing and optimizing time of the surgeries. neubauer and stewart [7] aimed to improve service quality and decreasing the costs as they found it is difficult to make the transition from the simple model to modeling and simulating actual processes on the computer, suggestions were made to others who may want to utilize arena software to bring the process modeling into the public affairs and administration curriculum. r. mathur et al. [8] obtained arrangement, order of the facilities and the efficient locations. the industry of utensils was a typical example of a work-flow shop that based production system. also they pursued to explore and improve the current factory layout by making an attempt to imitate the current and the proposed factory layouts by using arena software. faisal et al. [9] aimed to understand the attitude of a system or estimating strategies for the operation of the system, arena was used to comprehend the standing layout and the utilization of each station was optimized. muralidaran and sandeep [10] studied basically the analysis of an existent layout in a pump manufacturing industry. they analyzed the factory layout of manufacturing system, and an attempt has been made to mimic the existing layout of the industry by using the arena software. stopper and stuja [11] presented in arena a two different solutions for cycle time improvement based on a flexible manufacturing cell for treating cover parts. marsudi and shafeek [12] aimed to imitate the production process of a metal stamping industry and to estimate the utilization of the production line by using arena simulation software. this work focused on evaluating an improving in existing yogurt production line; abu ghraib dairy factory in iraq which has several machines of food processing and packing. arena software is applied for simulating and analyzing the current state of the production system, and results are expanded to improve the system production and efficiency. 2. simulation methodology 2.1. real-world system production the system production is a fill seal 4l which is an automatic filling/thermo sealing machine (shown in fig.1.) manufactured by means of the most modern construction methods and made of high quality materials such as stainless steel and anodized aluminum duly treated against the corrosion. fig. 1. fill seal 4l production machine. the machine consists of the following: 1. basement: the base represents the machine body and all parts are installed on it such kawthar a. mohammed al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 7178 (2019) 73 pneumatic and electric members. to access the base, it is necessary to remove the side covers by means of the endowed keys. 2. cups denester: the cup denester is the first operative station. its function is to denest and to transfer the cups from the store into the cup holder. two forks with double section. being driven by a pneumatic cylinder, make the separation of a container from the pile. 3. dosing station: after being destacked, the cups are filled by means of a volumetric doser endowed with a dosing regulator. on the doser there is a hopper for containing the product. the doser is entirely made of aisi 316 stainless steel and it is formed of a cylinder inside which there is a special sucking-pumping piston and of pneumatic dispenser which keep in sucking phase the product is brought from the hopper to the suction chamber. 4. sealing station: the sealing station performs the most important task of the packaging cycle. in fact, the sealing efficiency depends on the correct working of this station (on the quality of the employed materials and on the compatibility of the cup with the thermo sealing lid too) and vouches on a good preservation of product. the sealing station thermo seals the lids on the containers. 5. ejection station: it is the last station of the normal packaging cycle and makes the ejection of container from the machine. this station is usually formed by 3 main parts: the elevator, the pusher, and the carrying ejection conveyor with continuous operation. 6. control panel: the control panel is the interface that allows the operator to set the parameters of the machine and check for proper operation. the control panel consist of start button, stop button, emergency button, reset button and touch screen panel. 2.2. real-world system modelling the time has been calculated manually of each process (in seconds) 30 times. after calculating the data, the real-world process is simulated and modeled in arena software. figure (2) represent the model for all the processes in arena. fig. 2. arena model of the processes. the arena model in this work consists of the following processes: 1. product entry process. 2. material filling 3. sheet covering 4. can sealing 5. product exit process by using input analyzer in arena, the distribution diagram is obtained for each process. figure (3), (4), (5), (6), and (7) show the distribution diagram for product entry process, material filling, sheet covering, can sealing, and product exit process respectively. and data analysis for this process. fig. 3. distribution diagram for product entry process. fig. 4. distribution diagram for material filling process. kawthar a. mohammed al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 7178 (2019) 74 fig. 5. distribution diagram for sheet covering process. fig. 6. distribution diagram for can sealing process. fig. 7. distribution diagram for product exit process. 3. results and discussion 3.1. input results analysis the production line model has been modified to mimics the actual system based on production rate. table (1) illustrates designed plan of the system to run the production, the data that used to compare with the simulation model outcomes and analyzing improvement chances. table 1, designed plan of the system. # characteristic value 1 number of processes 5 2 number of buffers 4 3 number of shifts 1 4 designed production 5118 products 5 production rate 4.22 sec. 6 run per shift 6 hr. 7 run length 21600 sec. the input results for each process and for the buffering can be discussed as the following: 1. processes inputs system processing time is a leading factor for characterizing the performance in terms of production rate and demand responsiveness. figures (8), (9), (10), (11), and (13) show input data for the simulation model for system processes entering, filling, covering, sealing, and exiting respectively. presented data is the experimental sample size collections for each process that planned to be 30 observations for each experiment. collection analysis shows an expected homogeneity that can be observed depending statistical variability of the system (mean, standard deviation.) as following: (entering: 4.72, 0.284), (filling: 3.036, 0.152), (covering: 3.42, 0.359), (sealing: 2.60, 0.162), and (exiting: 3.319, 0.224), all values are measured in seconds. fig. 8. observation data for entering process. fig. 9. observation data for filling process. fig. 10. observation data for covering process. kawthar a. mohammed al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 7178 (2019) 75 fig. 11. observation data for sealing process. fig. 12. observation data for exiting process. 2. process buffering inputs an automated system is required a standard size of buffering which makes storage capacity for each process is constant and basically controlled for future improvement. collected data analysis for the system shows an expected stability can be analyzed for ignoring the buffering variability of the system (max., min.) as following: (for filling: 37.82, 37.02), (for covering: 17.33, 16.49), (for sealing: 18.41, 17.39), and (for exiting: 16.91, 15.69), all values are measured in seconds. in the real-world, the system has been designed for a constant capacity of product, and the observed variability is technically can be caused by the voltage fluctuations of conveyors motor. figures (13), (14), (15), and (16) show input data description for modeling the system conveyors and buffers. fig. 13. input data for buffering time of filling process. fig. 14. input data for buffering time of covering process. fig. 15. input data for buffering time of sealing process. kawthar a. mohammed al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 7178 (2019) 76 fig. 16. input data for buffering time of exiting process. 3.2. outcome results analysis the model of yogurt production has been running many times to get a set of experimental date for the purpose of results validity and dependability. results analysis verifies a strong validity for improvement chances and future planning of the system. table (2) illustrates the characteristic results of the performance and improvements that are traveling time of products in buffering for each process (waiting time), number of seized products at each buffer (waiting number), and the used capacity of system resources in producing parts (utilization). moreover, other characters are resulted such as number of planned part (number in), number of produced parts (number out), and system leading time (total production time) for the analysis. table 2, characteristic results analysis. filling process covering process sealing process exiting process waiting time 0.0 0.0 0.0 0.0 waiting number 0.0 0.0 0.0 1.0 utilization 0.6557 0.7215 0.5500 0.7000 number in 4,566 number out 4,563 total time 12.5 results analysis of the waiting time and number as zeros approves the non-need to model the buffering for each process as automated system. the production rate is closely similar to the designed production that stated in previous table (2), observed difference in the production as is related for the current running situation of the local zone due to the instability of the commitment to the business time/days. regarding to resources utilization, it is clearly shown that system is stable with a need to resetting the capacity as a chance for the improvement. re-planning resources capacity positively enhances the production and profitability of the system. figure (17) visualizes utilizations distribution for each process and difference that can be used in the re-planning for improving the system. in the research, the evolution process of the real system is done through analysis of the capacity of output products and the result shows that the system is stable with demand. there are many difficulties arise through implementation of the research such as lack of local factories, even that the abu ghraib dairy factory is not work for full time. fig. 17. utilizations distribution for the processes. in general, below % 80 of the resources utilization is completely secured the system running for a long production term as well as proving a reasonable chance for increase the demand responsiveness of the system that makes the improvements are possible. % 0.7215 is observed at the covering process that criticizes the improvements but on the other hand makes the system planner is able to analyze the capability limits of the system for future investments. 4. conclusion according to the results, a simulation method help researcher to build a software model which is mimics the real system. conducting experiments on the model allows the researchers to analyze the real system and predicates future behaviors. arena kawthar a. mohammed al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 7178 (2019) 77 is one of simple and professional simulation software which is used to simulate the yogurt production line. the validation of the experimental results of output products and actual number of products is closed to 98%. 5. references [1] m. bruqi, r. likaj, j. kacani, and a. gjukaj, "modeling and simulation of flexible system for electrical machine assembling", international research/expert conference, dubai, uae, 10-12 september 2012. [2] wilson r. nyembaa and charles mbohwab, "modelling, simulation and optimization of the materials flow of a multi-product assembling plant", procedia manufacturing journal, vol. 8, pages 59-66, 2017. [3] r. mathur, d. shringi, a. k. verma, "facility layout optimization using simulation: a case study of a steel utensils industry", vol. 3, issue 3, march 2016. [4] m. s. eryilmaza, a. o. kusakcib, h. gavranovicc, f. findikd, " analysis of shoe manufacturing factory by simulation of production processes", southeast europe journal of soft computing, vol.1, no.1, march 2012. [5] r. p. nithin, s. gopikrishnan, a. sumesh, " a case study on simulation and design optimization to improve productivity in cooling tower manufacturing industry", journal of iop conference series: materials science and engineering, vol. 310, conference 1, 2018. [6] j. a. lopez, c.i. lopez, j.e. olguin, c. camargo, and j. m. lopez, "surgery scheduling using simulation with arena", international journal of medical, health, biomedical, bioengineering and pharmaceutical engineering vol.7, no.7, 2013. [7] bruce j. neubauer and shelley k. stewart, "introduction of government process modeling with rockwell arena software", journal of public affairs education. vol.15, no.3, 2009. [8] r. mathur, d. shringi, a. k. verma, " facility layout optimization using simulation: a case study of a steel utensils industry", international journal of advance engineering and research development vol. 3, issue 3, march 2016. [9] faisal kp, falah ummer, hareesh k c, munavir ayaniyat, nijab k, nikesh p, jibi r," analysis and simulation of crankshaft manufacturing unit using arena", international journal of scientific and research publications, vol. 5, issue 2, february 2015. [10] manivel muralidaran v., sandeep, " layout planning in a pump manufacturing industry using arena", international journal of scientific & engineering research, vol. 5, issue 5, may 2014. [11] stopper, m. & stuja, k.," optimizing cycle time of a flexible manufacturing cell using simulation software", 4th international daaam conference, tallinn, estonia, 29 30th april 2004. [12] muhammad marsudi, hani shafeek, " the evaluation of production line performance by using arena – a case study", international journal of industrial and manufacturing engineering, vol.7, no.9, 2013. )2019( 7178، صفحة 4العدد ،15دجلة الخوارزمي الهندسية المجلم كوثر عبد الحميد محمد 78 لبان باستخدام برنامج المحاكاة أريناايم خط انتاج وتق مراد*** كوثر عبد الحميد محمد حسن* علي حسين كاظم** أمير حسين *، ** قسم هندسة التصنيع المؤتمت/ كلية الهندسة الخوارزمي/ جامعة بغداد/ العراق *** قسم هندسة المعلومات واالتصاالت/ كلية الهندسة الخوارزمي/ جامعة بغداد/ العراق kawthar.abd.alhameed@gmail.comبريد االلكتروني: *ال yahoo.com59kadhumali@**البريد االلكتروني: ameer_morad@yahoo.com***البريد االلكتروني: الخالصة من البحث هو تحديد قابلية التحكم في نظام انتاجي حالي؛ خط إنتاج الزبادي في مصنع أبو غريب لأللبان والذي يحتوي على العديد من ئيسالغرض الر التحليل بناًء تم تصميم كما آالت تصنيع وتغليف المواد الغذائية التي تمت دراستها. من خالل بدء التحليل، تم العثور على عدم استقرارية في اإلنتاج في المصنع زمنية مختلفة من معالجة الماكينات، وقد تم إجراء التحليل اإلحصائي لنمذجة نظام اإلنتاج. يتم تطبيق برنامج أرينا مدةعلى المالحظة التجريبية وجمع البيانات ل arena وكفاءته. تم تطبيق طريقة البحث للمساهمة في معرفة وتوقع لمحاكاة الحالة الراهنة لنظام اإلنتاج وتحليلها، ويتم تفصيل النتائج لتحسين إنتاج النظام للتجربة في برنامج ذلك، يتم بناء نموذج حقيقي فظال عنالتشغيل المستقبلي للنظام لتعزيز قابلية التحكم في إنتاج النظام وتحسين نظام اإلنتاج وكفاءة الماكينة. والعملية. الخطوة األولى هي جمع البيانات اإلحصائية المطلوبة للتحليل من حيث بيانات المدخالت من أجل التحكم في النظام من حيث اإلنتاج arenaأرينا فادة من النظام. الخطوة الثالثة هو التحقق من صحة والمخرجات للتحليل. الخطوة الثانية، هي تتبع مشكلة اإلنتاج وعوائق العملية التي تحدث من أجل تحسين اإل لب على الطلب على المنتج عند عدم إمكانية التحكم في النظام. من خالل تحليل نتائج وقت االنتظار ومعدل اإلنتاج، يتضح بوضوح أن النموذج من أجل التغ جابي إنتاج إعادة تخطيط قدرة الموارد تعزز بشكل إي إن للتحسين، فيما يتعلق باستخدام الموارد فرصةً بوصفها النظام مستقر مع الحاجة إلى إعادة تعيين القدرة ٪.٩٨تبلغ نسبة التحقق من صحة النتائج التجريبية للمنتجات المخرجات والعدد الفعلي للمنتجات حوالي .تهوربحي النظام al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 2132 (2014) experimental and analytical study of bending stresses and deflections in curved beam made of laminated composite material assma hassan ismail department of mechanical engineering / university of baghdad email:asma.sawaf@yahoo.com (received 21 april 2014; accepted 22 september 2014) abstract theoretical and experimental methodologies were assessed to test curved beam made of layered composite material. the maximum stress and maximum deflection were computed for each layer and the effect of radius of curvature and curve shape on them. because of the increase of the use of composite materials in aircraft structures and the renewed interest in these types of problems, the presented theoretical assessment was made using three different approaches: curved beam theory and an approximate 2d strength of material equations and finite element method (fem) analysis by ansys 14.5 program for twelve cases of multi-layered cylindrical shell panel differs in fiber orientations and number of layers. one case of e-glass composite material was experimentally made and tested to verify the relation between applied load and maximum deflection and four models were made of poly carbonyl to determine stresses under bending loads in polar scope, all results were compared with each other, the percentage accuracy was very good. the curved beam theory and strength of material equation formulas results were reasonable for the bottom surface, while it seems not enough for the top surfaces. also, results explained positions and cases more affected by delaminating and the most preferred part of ellipse shape beam in resisting loads. keywords: curved beam theory, composite material, strength of materials, finite element method. 1. introduction material made into fiber forms can achieve significantly. better mechanical properties than their bulk counter-parts fibers alone are not suitable for structural application to utilize the superior properties of fibers; they are embedded in matrix material that holds the fibers together to form a solid body capable of carrying complex loads. matrix materials that are currently used for forming composites include three major categories: polymers, metals and ceramics. fiber composites are stiff, strong and light and are thus most suitable for aircraft wing structures. they are often used in the form of laminates that consist of a number of unidirectional laminate with different fiber orientation. they provide multi directional load capacity composite laminates with excellent fatigue life, damage tolerance and corrosion resistance. curved beam structures made of composite materials have found many useful applications in aerospace engineering, civil engineering and the automobile industry .one of the active research fields is the modeling of composite rotor blades used on helicopters and tilt rotor aircrafts. numerous models have been developed for thin-walled composite beams over the last several decades [4]. a review and analysis of various theories can be obtained in papers of; [4] when the variation–asymptotic method has been applied to develop an asymptotically correct model for initially curved and twisted, thin-walled, composite beams of arbitrary cross-sectional shapes and arbitrary anisotropic materials. in a two-step asymptotic reduction procedure, the three-dimensional strain energy is asymptotically reduced first to a two-dimensional shell strain energy and then to a one-dimensional beam strain assma hassan ismail al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 2132 (2014) 22 energy. this is a new attempt where initially curved and twisted, thin-walled, composite beams, with open or closed sections, have been modeled in an asymptotically correct unified framework.[9], analyzed an efficient procedure naturally curved and twisted beams with general cross-sectional shapes using naturally curved and twisted beam; st.venant tensional warping function; generalized coordinate for warping; the minimum potential energy principle take into account the effects of torsion-related warping as well as transverse shear deformations, solutions can be used to calculate various internal forces, stresses, strains and displacements of the beams [10] developed modeling and dynamic response to blast loadings of doubly-curved sandwich panels with laminated face sheets. the implications of the panel curvature, of anisotropy and stacking sequence of face sheets, of transverse orthotropic of the core and of structural damping on dynamic response to time-dependent loads are highlighted [11], applied the finite element-based beam analysis for anisotropic beams with arbitrary-shaped crosssections with the aid of a formal asymptotic expansion method. from the equilibrium equations of the linear three-dimensional (3d) elasticity, a set of the microscopic 2d and macroscopic 1d equation are systematically derived by introducing the virtual work concept. displacements at each order are split into two parts, such as fundamental and warping solutions, the numerical results are compared to those reported in literature as well as 3d fem solutions [13] ,performed a curved beam element for the analysis of large deformation of flexible multi-body systems using the absolute nodal coordinate formulation. using the green– lagrange strain tensor as a volume element, locking phenomenon associated with the shear and cross-section deformation leads to erroneously stiffer bending characteristics, numerical examples are presented in order to demonstrate the performance of the curved beam element developed in this investigation [7], presented a theory of space curved beams with arbitrary cross– sections and an associated finite element formulation. applying the isoperimetric concept, the kinematic quantities are approximated using lagrangian interpolation functions. alternative discretizations of thin–walled cross–sections with shell elements showed good agreement between the different models. thus, the derived element can effectively be used to analyze the load–carrying capacities of special beam structures. the object of this research is comparing between results of experimentally and theoretical methods of maximum stress and deflection for composite laminated curved thin beam (quarter of circle) with one fixed end and study the effect of changing the fiber orientation arrangement, symmetry about the middle surface plane. theoretical methods are strength of material equation, curved beam theory and finite element method for twelve different cases. one experimentally model is manufactured to measure the maximum beam deflection for verification. then using ansys graphs to obtain the change of the maximum stress positions as the mentioned parameters change, and then taking ellipse shape beam with same previous length and base radius in ansys to show the change in maximum stress and deflection and how much it is better. 2. analytical equations the tangential and radial stresses of curved beam figure1. according to advanced strength of material (generally) are: fig. 1. section of curved beam. …(1) …(2) …(3) for rectangular section [1]: ) 1 ( r ro bln r da  …(4) for composite material these stresses are changed to: ...(6)       r da a rn a r da rn baer m r aer rrnm ]1[ 1 )(         e e a r da rn baer m r e e aer rrnm       ]1[ 1 )( assma hassan ismail al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 2132 (2014) 23 where e is the change in the elastic modulus according to the number of layer and fiber orientation,the equations of elastic modulus in fiber direction or perpendicular to fiber orientation. according to maxwell reciprocal theorem are [2]; …(7) 3. curved beam theory the differential equations of equilibrium in polar coordinates could be simplified to [5]: 0)()( 0)()( 0)()(                rqm nq qn …(8) the force and moment resultants are integrals of the stresses over the beam thickness (h) are:                                                                     k a db ba m n h h z bm n f f 55 00 0 1111 0 1111 2/ 2/ …(9) determining eѳ every layer which differs from n to l, then; …(10) …(11) …(12) for thin beams the middle surface strain and curvature k changes are: …(13) finding  from equations (10), then tangential stress is determined from; …(14) in this case, when a quarter circle beams with one fixed end is subjected to bending force in the other end will have; …(15) the deflections in x and y directions derived from strain and displacement equations; ...(16) 4. finite element method ansys, the ultimate purpose of a finite element analysis is to re-create mathematically the behavior of an actual engineering system. in other words, the analysis must be an accurate mathematical model of a physical prototype. in the broadest sense, the model comprises all the, material properties, real constants, boundary conditions and the other features that used to represent the physical system. in ansys14 2 21 1 12 12 2 1 ** ** * ** e v e v vvvvv veve ee e vevee mmff fmmf mf mmff      2112 11 1     e q dz l h l h zr rzn l qbb dz l h l h zr rn l qba             1 1 1111 1 1 1111 dz k h k h h zn k qba d k h k h zr rzn k qbd            1 2 2 4 1 1 1155 1 2 1 1111 2 2 { 2 1 1             wu k wu r rr   11q    psinf pcosn prcosm    wru kr r kr rw i ii i           cos 2 cos 2 sin 2 22 assma hassan ismail al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 2132 (2014) 24 terminology, the term model generation usually takes on the narrower meaning of generating the nodes and elements that represent the special volume and connectivity of the actual system. thus, model generation in this study will mean the process of defining the geometric configuration of the model's nodes and elements, shell281. figure 2 element is used in this study. the element is suitable for analyzing thin to moderately-thick shell structures. the element has eight nodes with six degrees of freedom at each node: translations in the x, y, and z axes, and rotations about the x, y, and z-axes. it may be used for layered applications for modeling composite shells or sandwich construction figure 3 [mouveni]. fig. 2. shell 281 elements. fig. 3. curved beam mesh. 5. manufacturing steps make the block from wood in the selected dimensions with small clearance, varnish the inside surface of block by anti-adhesion, stuff the glass fibers were cut in pieces in the selected length carefully, fill the prepared epoxy on the first layer in the specified weight, repeat the same until three layers completion, leave the filled block for hours until it stick together, then take the composed material out of the block carefully, put the material on a prepared circular surface with the specified radius and varnished ,use the antibubble roller to prevent creating of bubbles ,the specimen will be ready after two or three days and needs only filing by file to fit the dimensions by virneir. 6. experimental test composite laminated curved (quarter of circle) thin beam is (hand layout) manufactured properties mentioned in table.1. in three layers fig. 4. 0/90/0, fiber angles the dimensions are; r=15.7 cm, width=2.54 cm, thickness=3 mm each layer is one millimeter. fig. 4. manufactured beams. fig. 5. polar scope. table 1, properties of material used. epoxy e-glass fiber property 4.5 74 young modulus gp 1200 2600 density kg/m3 0.4 0.25 poisson ratio ʋ assma hassan ismail al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 2132 (2014) 25 7. photo elastic test four models, three different positions were selected from one ellipse which had the same bigger radius with the previous manufactured curved beam with one quarter in order to indicate the best model in resisting the loads applied in all directions; the small radius was 95.4mm fig.5.by polar scope fig.6. the photo elastic material is poly carbonyl, the fringe coefficient is 6.9n/mm/fringe and the used equation is; …(17) where f is fringe coefficient and n is number of fringes and t is poly carbonyl thickness which is 3.5mm. fig. 6 . deflection tester. 8. results table (1) and figure (7) indicates the experimentally results of maximum deflection test by dial gage fig.6. for increasing the load from 0.5n to 3n is very coincident to ansys values, figures (8,9,10 ) for one layer (0, 45, 90 angles) indicates that the stress distributions are the same the difference in stress value is small but obvious in deflection the deflection decreased with increasing of fiber angle from 0 to 90 .for two layers figures (13,12 ) for 0/90 and 0/45 the shear stress is obviously increased exposing the layers to delamination ,this increase arising from the asymmetry of fiber orientation about the middle surface, the point of maximum shear stress is at angle 45 from fixed end .for figures (14,11), three layers (0/0/90, 45/45/0), two layers (0/90) also the same note because of asymmetry. while table(4) of ansys results indicates the higher value of deflection was at third case ( one layer 90 fiber angle because of the low value of hoop elastic modulus ,the lower value was at case (0/90/0) because of the symmetry of fibers about the middle surface, higher stress was in case of two layers 0/90, 0/45,three layers45/45/0 obviously also because of asymmetry the less stress and deflection was at cases 0,0/0,0/0/0.figures 15 to 18 ,and table (5), gave the photo elastic test results which gave the good coincidence with ansys results, the most suitable position in ellipse was the third model as it indicated in table because the stress became less obviously , figures (19,20,21) indicates the stress distribution in the ellipse shape beam for the same length and same base circle radius which is smaller 32% in stress and 90% table (6) of strength of material equation gave the same as in ansys where the less stress and less deflection was at zero angle ,higher stresses in 0/90 and 45/45/0.the curved beam theory method gave also the higher values of stresses in 0/90 and 0/45, less values at zero angles as in table (6).the increase in no. of layers from 1 to 3 increase the stress and deflection little as figures (23,24),and the effect of increasing fiber angle from 0 to 90 indicated in figures (24,25). figures (26, 27) indicates the difference in values of deflections and stresses in twelve cases between three theoretical methods stm,cbt,fem. the radius of curvature increase gave increase in strength by lowering the stress induced, and decreases the delamination possibility also because the shear stresses decrease as figure (28, 29). that means ellipse shape beam is more suitable shape for structures. 9. list of graphs table 2, experiment deflection results compared with ansys for 0/90/0 case. 3 2.5 2 1.5 1 0.5 load n 0.6 0.5 0.4 0.3 0.2 0.1 deflection cm 0.64 0.53 0.42 0.32 0.21 0.1 ansys results cm t nf . 21  assma hassan ismail al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 2132 (2014) 26 fig. 7. experimentally change of deflection with load. fig. 8. stress in y direction in one layer 0 fiber angle. fig. 9. stress in y direction in one layer for 45 fiber angle. fig.10. stress in y direction in one layer 90 fiber angle. fig. 11. shear stress in xy direction in 45/45/0 fiber angle in second layer. fig. 12. shear stress in xy direction in first layer for two 0/90 layer. fig. 11. shear stress in xz direction in second 0/45 fiber angle for two layers. fig. 13. shear stress in xy direction in first layer for three layers 0/0/90 fiber angle. assma hassan ismail al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 2132 (2014) 27 fig. 15. first beam in polar scope under 2.25n load. fig. 16. forth beam in polar scope under 2.25n load. fig. 17. second beam in polar scope under 2.25n load. fig.18. third ellipse shape beam in polar scope under 2.25n load. fig. 19. second ellipse shape beam in ansys. fig. 20. fourth ellipse shape beam in ansys. fig. 21.third ellipse shape beam in ansys. fig. 22. change of deflection in y direction with no.of layers. assma hassan ismail al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 2132 (2014) 28 fig. 23. change of stress y direction with no. of layers. fig. 24.change of stress in y direction with fiber angle. fig. 25. change of stress in y direction with fiber. fig. 26. comparison in deflection values between three methods for twelve cases. fig. 27. comparison in stress values between three methods for twelve cases. fig. 28. change of stress with radius of curvature. fig. 29. change of deflection with radius of curvature. fig. 30.change of deflection with mesh degree. assma hassan ismail al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 2132 (2014) 29 10. list of tables table 3, ansys 14.5 results maximum tangential stress mpa deflection max cm case third layer second layer first layer 16.96 0.5261 0 1 15.46 2.386 45 2 14.81 1.879 90 3 16.172 16.96 0.526 0/0 4 9.41 23.35 1.096 0/90 5 23.55 13.72 1.035 0/45 6 15.08 0.7306 16.96 0.52616 0/0/0 7 14.64 4.398 17.25 0.5059 0/90/0 8 10.77 3.369 22.45 0.8605 0/0/90 9 20.25 0.6457 21.21 1.679 45/0/45 10 19.2 1.775 19.81 1.093 45/-45/45 11 23.1 6.08 12.17 1.861 45/45/0 12 table 4, strength of materials equation results. maximum tangential stress mpa deflection max cm case third layer second layer first layer 9.78 0.47947 0 1 9.78 1.85 45 2 9.78 0.5388 90 3 10.8 9.78 0.5402 0/0 4 27. 9.78 0.67526 0/90 5 12. 9.78 0.492 0/45 6 14. 9.78 0.6752 0/0/0 7 16.2 9.78 0.81 0/90/0 8 11.57 9.78 0.5788 0/0/90 9 11.57 9.78 0.6023 45/0/45 10 11. 9.78 0.6025 45/-45/45 11 22.561 9.87 0.719 45/45/0 12 table 5, curved beam theory results maximum tangential stress mpa deflection max cm case third layer second layer first layer 16.578 0.4257 0 1 14.037085 1.752 45 2 16.6658 0.5389 90 3 11.5881 17.3876 0.5327 0/0 4 7.41 19.919 0.7316 0/90 5 14.2355 19.72 0.7819 0/45 6 5.9547 11.906 17.7435 0.6433 0/0/0 7 5.456 5.809 16.4189 0.6236 0/90/0 8 5.9517 11.9034 17.86 0.6436 0/0/90 9 11.4247 10.34357 13.5391 0.4552 45/0/45 10 6.7542 14.636 17.7154 .6412 45/-45/45 11 11.5441 11.308 13.6817 0.4595 45/45/0 12 assma hassan ismail al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 2132 (2014) 30 table 6, polari scope pictures results. 11. conclusions 1. the middle layer is subjected to less stress because the moment center pass through it where the resultant stress is zero. 2. unsummetry of layers fiber angle about the geometrical center makes greater generated stress than the same layers but in symmetrical arrangement,and high difference in stress between top and bottom layers, high x,y shear stress which make delaminating more possible because of torsion effect. 3. theoretically increasing layers makes young modulus less than the material first young modulus that increase the generated stress, but in ansys the change in stress is very small for laminars from 1 to three layers, it analyze stresses in three dimensions and indicate that the value of z direction stress which is ignored in cbt and sm methods is not zero that is one of difference reasons in results. 4. the accuracy is obvious between cbt and ansys for the stress in the bottom layer which equals 95% and between sm and ansys is 65% but the difference is clear for the top layer. 5. the experimentally founded values of deflections coincide the deflections of other methods in 95% percentage. 6. the ellipse shape beam is more suitable for aircraft structures, and third shape is the most preferred because the stress was less. 12. list of symbols of materials equation strength stm curved beam theory cbt finite element method fem strain ɵ n/m2 stress in tangential direction ɵ poisson ratio of total composit material 21ʋ 12,ʋ , ʋ poisson ratio of fiber f ʋ poisson ratio of matrix m ʋ m displacement in tangential and longitudinal direction w,u m second derivative of tangential displacement w volumetric ratio of fiber vf volumetric ratio of matrix vm n/m2 young modulus of composite material in tangential direction e ɵ n/m2 young modulus of composite material in radial direction e r n/m2 young modulus of composite material in fiber direction e1 n/m2 young modulus of material in direction perpendicular to fiber e2 n/m2 young modulus of fibers e f n/m2 young modulus of matrix e m m curvature radius of k m radius of beam section at center of bending stress rn m outside radius of beam section ro m2 beam section area a n applied force in y direction n,p n.m bending moment m n shear force f degree angle of any section of beam from x-axis ɵ m inner radius ri m thickness at any point z m thickness h m width of beam b m difference between geometrical center and bending center e m4 moment of inertia i 13. references [1] r.g.budynas, advanced strength and applied stress analysis, rochester institute of technology. [2] r. m.jones,mechanics of composite materials,southern methodist university. [3] s. mouveni “finite element analysis” theory and application with ansys, 1999.m q applied force in y direction bending moment shear force. [4] [sitikantha(2006), an asymptotically correct model for initially curved and twisted thinwalled composite beams, department of mechanical and aerospace engineering, utah state university, logan, ut 803224130, usa. [5] r.m. guedes1,numerical analysis of singly curved shallow composite panels under three-point bend load,1departamento de engenharia mecânica e gestão industrial, faculdade de engenharia da universidade do principal stress difference mp δϭ number of fringes photo elastic case first 7 2 second 4 3.5 third 10 5 fourth assma hassan ismail al-khwarizmi engineering journal, vol. 10, no. 4, p.p. 2132 (2014) 31 porto, rua dr. roberto frias s/n, 4200-465 porto, portugal 2inegi, instituto de engenharia mecânica e gestão industrial, portugal. [6] j. li (2000), a geometrically exact curved beam theory and its finite element formulation/ implementation, thesis of the virginia polytechnic institute and state university in partial fulfillment of the requirements for the degree of master of science in aerospace. [7] f. gruttmann1 (2000), theory and numeric of three dimensional beams with elastic plastic material behavior, published in institute fur statik, technische universit¨at darmstadt, 64283 darmstadt, germany ,2 ingenieurb¨uro j¨ager, 01445 radebeul, germany,3 institut f¨ur baustatik, universit¨at karlsruhe, 76128 karlsruhe, germany. [8] brauner(2005),advanced nonlinear failure analysis of a reinforcement composite curved beam with delamination and ply degradation, samtech s.a., liège science park, liège, belgium. [9] a.m.yu (2005), generalized coordinate for warping of naturally curved and twisted beams with general cross-sectional shapes, school of aerospace engineering and applied mechanics, tongji university, shanghai 200092, china. [10] t. hause (2007), dynamic response of doubly-curved anisotropic sandwich panels impacted by blast loadings, department of engineering science and mechanics, virginia tech, blacksburg, va 24061, usa.. [11] j.s. kim (2007), an asymptotic analysis of composite beams with kinematically corrected end effects, seoul national university, seoul 151-742, republic of korea. [12] t.abduljabbar (1978), photo elastic analysis of a plate performed with patterns of four circular holes, a thesis of master of science, baghdad university/mechanical department. [13] h sugiyama(2006), a curved beam element in the analysis of flexible multi-body systems using the absolute nodal coordinates, center for collaborative research, university of tokyo, tokyo, japa, 10.1243/1464419jmbd86 (2014) 2132، صفحت 4، العذد10دجلت الخىارزمي الهنذسيت المجلم اسماء حسن اسماعيل 32 دراست تحليليت وعمليت ألجهاداث االنحناء والتمذد في عمىد مقىس مصنىع من مادة مركبت راث طبقاث أسماء حسن أسماعيل صايؼت بغذاد/كهٍت انُٓذست / لسى انُٓذست انًٍكاٍَكٍت asma.sawaf@yahoo.com : انبرٌذ االنكخرًَٔ الخالصت يغ بٍاٌ طرق َظرٌت ٔػًهٍت نفحص ػًٕد يمٕش يصُٕع يٍ يادة يركبت يٍ ػذة طبماث حٍذ حى حساب االصٓاد ٔانًٍم االلصى نكم طبمتث أػخًذ صذد االًٍْت فأٌ انبحذ انًمذو فً انطائراث ٔنكَّٕ يٕضٕع يج السًٍاَظرا نسٌادة االسخخذاو نهًٕاد انًركبت .حأرٍر َصف لطر انخمٕش ٔشكم انخمٕش ػهٍٓا حانت يخخهفت فً ةي ػشرثطرٌمت انؼُصر انًحذد الرٍ ٔيؼادالث يمأيت انًٕاد رُائٍت االبؼاد , شَظرٌت انؼًٕد انًمٕي اسخخذو رالد طرق َظرٌت يخخهفت ِٔ ٔاربؼت ًَارس يٍ ٔفحصّ نبٍاٌ ػاللت انحًم بانخًذد االلصى كًا حى حصٍُغ ًَٕرس نحانت ٔاحذة يٍ انٍاف انسصاس ٔاالٌبٕكسً .زٔاٌا االنٍاف ٔػذد انطبماث يغ بؼضٓا انبؼضكهٓا انُخائش لٕرَج ٔ, يادة انبٕنٍكاربٍَٕم السخخذايٓا فً صٓاز انًرَٔت انضٕئٍت نبٍاٌ حٕزٌغ االصٓاداث ححج حأرٍر احًال االَحُاء انُخائش انخاصت بطرٌمت َظرٌت انؼًٕد انًمٕش ٔطرٌمت يمأيت انًٕاد يؼمٕنت نهطبمت انسفهى بشكم ٔاضح ٔنكُٓا نى حكٍ ٔكاَج صٍذة صذا َسبت حطابك اػطج ٔ يمٕش االفضم يٍ كم النشكافٍت انذلت نهطبمت انؼهٍا نهؼٍُاث كًا اظٓرث َخائش انبرَايش انصٕرٌت انًٕالغ ٔانحاالث االكزر ػرضت نحانت اَفصال انطبماث ٔا .ٔالغ انًخخهفت يٍ انؼًٕد انبٍضٕي انشكمبٍٍ انى mailto:asma.sawaf@yahoo.com 79-89سحر عبد al-khwarizmi engineering journal al-khwarizmi engineering journal,vol. 13, no. 1, p.p. 7989 (2017) study the characterization of adding polymer-surfactant agent on the drag reduction phenomena in pipeline flow system sahar a. dawood department of chemical engineering /university of technology email: sahar_abd60@yahoo.com (received 30 june 2016; accepted 7 december 2016) https://doi.org/10.22153/kej.2017.12.004 abstract in this study, the effect of carboxylic methyl cellulose (cmc), and sodium dodcyl benzene sulfonate (sdbs) as an aqueous solution on the drag reduction was investigated. different concentrations of (cmc) and (sdbs) such as (50, 100, 150, 200, 250, 300, 350, 400, 450, and 500 ppm) were used to analyze the aqueous solution properties, including surface tension, conductivity, and shear viscosity. the optimum four concentrations (i.e., 50, 100, 200, and 300 ppm) of fluid properties were utilized to find their effect on the drag reduction. two different pvc pipe diameters (i.e., 1" and 3/4") were used in this work. the results showed that blending cmc with sdbs gives a good drag reduction percent about (58%) more than using them individually, friction factor decreasing with increasing reynolds number and gives good agreement with von karamn equation and maximum drag reduction (mdr) asymptote. reynolds number, pipe diameter, and polymer-surfactant concentrations were considered as influencing factors. in addition, critical micelle concentration, the onset of drag reduction, and the interactions between the mixed additives were discussed. keyword: cmc, sdbs, drag reduction, friction factor, blending of additives. 1. introduction due to a wide extent of employment of surfactants and polymers, an extensive number of studies have been done on the depiction and attributes of surface-active-agent and polymer solutions. the balance in the interaction between the solvent and aqua phobic and aqua public segments of the polymer determines the solubility of a given polymer in solvent. the accumulation of surfactant molecules in aqueous solution depends on aqua phobic, aqua philic and ionic interactions. due to a broad variety of molecular structures, polymer and surface-active-agent when blended unitedly in aqueous solution exhibit a species diversity and sometimes even very unusual pattern of attributes [1]. in the 1940s and 1950s, the study of interaction between proteins and synthetic ionic surfactants recognized the importance of electrical forces of attraction of charge groups. this led to the development of the concept of “binding” of charge surfactants by the polymer macromolecule to explain the conformational changes in polymer macromolecules [1]. the complexes formed due to interaction of polymer and surfactants has a remarkable influence on the system properties leading to regenerated concern in the area in the current decades. however, many concepts traditionally used in polymer-surfactant studies need modification in order to be applicable to a wide variety of macromolecules such as hydrophobically modified polymers which are normally considered hydrophilic. in recent years, there has been a rising concern in reversely charged polymers and surface-active-agent due to their significance in both biological and technological utilizations [2, 3, 4]. they are also important in essential studies as coordinate to intermolecular influence and aquaphobic accumulation occurrence. in the case of reversible charged polymer and surfactants, both electrostatic and aquaphobic influences play a role. the characteristics of such combination pdf created with pdffactory trial version www.pdffactory.com mailto:sahar_abd60@yahoo.com https://doi.org/10.22153/kej.2017.12.004 http://www.pdffactory.com http://www.pdffactory.com sahar a. dawood al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 7989 (2017) 80 depend on many elements, such as surfactant chain length, backbone rigidity, polymer charge density and concentrations of polymer and surfactant [5]. the benefit of polymers and surfactants in mixing is found in a very wide extent of products, such as formulations of drugs and pesticides, detergents, paints, cosmetics, foods, polymer synthesis, and enhanced oil recovery. here, one or more polymer is used in combination with surfactant to achieve different effects, such as viscosity enhancement, colloidal stability, emulsification, solubilization, catalysis, gel formation, cloud point elevation, and enzymatic reactions, surface conditioning, usability improvement, detergency, foaming and phase separation [6]. besides the conventional uses of polymer and surfactant additives in altering solution properties, both polymers and surfactants are considered and are being used extensively as drag reducers to reduce the wall friction in turbulent pipe flow so as to increase the pump capacity or to reduce the pump power requirement. it has been found that little amount of certain contaminants in water can contribute to a great decrease in turbulent friction on the surface where the fluid flows or bodies moving through the fluid [1,6,7,8,9]. over sixty years’ extensive research in this field, additives like polymers, surfactants and air bubbles are discovered to be some of those “contaminants”, which is also termed as drag reduction agents (dras). by definition, dras are any material or additives that reduce frictional pressure during fluid in a conduit or pipeline. researchers and engineers also found dra has a variety of benefits, especially in industrial area. firstly, it is possible to decrease pressure drop for the same flow rate of fluid in pipelines or increase flow using the same amount of energy. then, as a prerequisite to maintain throughput, dra can reduce transportation time and carbon emissions of pump stations, moreover, avoid the consumption cost and total investment. certain dra can perform a drag-reducing ability up to 80% or increase flow rates by more than 100%. dr has been applied to numerous applications currently in a large number of fields, for example, water heating and cooling systems, flood water disposal, oil pipelines, firefighting, oil well operations, field irrigation, marine systems, transport of suspension and slurries, as well as airplane tank [3]. actually, as we know, drag reduction is not only limited in these aspects, it can also occur in some other fields created by humans spontaneously or in nature, where need to be further discovered in the future. the objective of this research is to investigate the possibility of interaction between polymers and surfactants; by means of measuring and analyzing several properties, such as surface tension, conductivity, shear viscosity and relative viscosity. to determine whether there exist a synergistic effect on drag reduction in transportation of polymer-surfactant solutions in the pipelines; pilot-scale experiments were carried out to test the flow behaviors of polymersurfactant solutions in pipelines. the collected data were compared with pure polymer solutions at the same conditions. the polymer selected was carboxyl methyl cellulose (cmc). anionic (sodium dodcyl benzene sulfonate) were selected as surfactant. two different diameter pipes, 1 inch and 3/4 inch, were utilized. the mass flow rate along with the pressure drop were measured and from these data, the drag reduction was calculated and compared to the drag reduction achieved by the pure polymer mixtures in the same setup. the mixtures were compared to find if they were more stable (slower degradation times), had a larger effective reynolds range, and if they achieved higher levels of drag reduction than the pure polymer solutions. 2. experimental work and method sodium dodcylbenzen sulfonate (sdbs) was selected as an anionic surfactant to add to an anionic polymer which is carboxyl methyl cellulose (cmc) [10, 11, 12], to develop a new combination of surfactant additive which would applied to tap water circulation in pipeline system for measuring the drag reduction behavior and performance. different equal concentrations of cmc and sdbs were prepared by mixing them in tap water (i.e.,50, 100, 200 and 300 ppm) (wt.%). the experimental system consists of four horizontal circulating pvc pipelines with 6 m long, pump, feed tank, and u-tube manometers, as shown in figure 1. testing sections were installed with a distance equal to 3 m. the first testing point was located at a distance enough to ensure the turbulent flow is fully developed before the testing section. volumetric flow rate was controlled by using flow meters and bypass return to the tank by a valve. for each flow rate reading, the pressure drop was measured by using manometer connected to the points in the test section. pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com sahar a. dawood al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 7989 (2017) 81 fig. 1. experimental rig. the pipe dimensions and test point locations are shown in table 1. table 1, pipe dimensions and test point locations. pipe no. internal diameter entrance length test section length meter meter meter 1 0.0254 (1") 1.35 3 2 0.01905 (3/4") 1.15 3 3 0.01905 (3/4") 2.15 3 4 0.0127 (1/2") 1.65 3 entrance length more than 50 times diameter (50.d) to ensure fully developed region before the test section. 3. experimental steps only two pipe diameters (1" and 3/4") were used to carry out the experimental work. the drag reduction( % ) in pipes is defined as: …(1) the subscript b, refers to pure solvent (water), and subscript a, after using additives. different concentrations (50, 100, 200, and 300 ppm), for the three additives (polymer, surfactant, and a mixture of them) were used. %dr for each solution was calculated using equation (1). each experiment was repeated about 3 times in order to obtain the accurate results. the measured data were compared with the theoretical assumptions presented by von karman equation and maximum drag reduction asymptote in turbulent regime [9]. von karman equation: …(2) mdr asymptote: …(3) where, is the friction coefficient calculated by the equation below: …(4) and is the shear stress and calculated from: …(5) re. no. in the pipe is calculated by: …(6) where v ,d , and η are the velocity of the fluid, the diameter of the pipe, and kinematic viscosity, respectively. finally, the du nuoy ring method was used to investigate the surface tension of the additive solutions with different concentrations (50,100, 150, 200, 250, 300, 350, 400, 450, and 500 ppm) as shown in figure 2. the specific conductance was investigated for the same concentrations as specified for surface tension investigation by using viscometer device (brook field) (dvii+pro viscometer) as shown in figure 3. fig. 2. surface tension device. fig. 3. viscometer device. pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com sahar a. dawood al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 7989 (2017) 82 4. results and discussion the effect of volumetric flow rate (q) measured in liters per minutes, on the percentage drag reduction (%dr) for aqueous solutions flowing in (3/4 " and 1") id pipe using cmc (50300 ppm) is shown in figure 4 (a & b). in figure 4a, the percentage of drag reduction increases more than 40% with increasing of the volumetric flow rate from 4 to 12 l/min. and decreases with further increases in volumetric flow rate for the pipe with a diameter of 3/4". low volumetric flow rate means low shear rate, where the polymer starts to make a thread like structures which interact with the turbulent eddies and burst them, causing the drag reduction, which is continually increasing until a point on shear rate, mechanical degradation of polymer chains in high shear rate regions, is frequently observed, which lowers the molecular weight and causes a loss of drag reduction [13]. several works that have been reported in the literature, studied the onset of drag reduction by dilution of polymer additives and the maximum drag reduction asymptote [11,14] in their researchs fixed the maximum drag reduction for polymer additives. the earlier work on the subject were made by toms [9], lumely [15], and landahi [16] who reported the effectiveness of drag reducing agent. also, as the concentration of cmc increases from 50 to 300 ppm, the percentage of the drag reduction increases for about 13% of low volumetric flow rate (i.e., 4 l/min.) and 5% at high volumetric flow rate (i.e., 24 l/min.), as shown in figure 4a. whenever increased concentration leading to increase the composition of thread like micelles. however, in figure 4b, it can be noticed that the percentage of the drag reduction is highly improved, where the drag reduction increased by about 20% at volumetric flow rates of 4 l/min. and 11% at 24 l/min. by using pipe diameter of 1" with increasing of the cmc concentration. large pipe diameter means low velocities and low reynolds number which may be in transition region which have more fluctuation. from this, it can be concluded that larger diameter gives better result on drag reduction percent than smaller diameter, the same behavior was noted with sdbs when used as a drag reducing agent in aqueous solution. fig. 4. (a, and b) relation between %dr and q (l/m) for cmc with different pipe diameters and concentrations. figure 5 (a, and b) shows the effect of volumetric flow rate on the percentage drag reduction for aqueous solution of different sdbs concentrations (i.e., 200, 300, and 400 ppm) by using 3/4" and 1" pipe diameters. figure 5a depicts that the percentage drag reduction of the fluid in sdbs concentration was not clear, and the results oscillated with increasing sdbs concentration. while in figure 5b, the behavior is clear by using 1" pipe diameter, it means that as the sdbs concentration increases, the percentage of the drag reduction is increasing and reaching maximum values (32, 45, and 52) % for (200, 300, and 400 ppm) concentration, respectively. the reduction occurs due to increasing the length of rod-like micelles and increasing an aggregation number of spherical micelles, similar results were shown by other workers [17-19] when the rode like micelles grow rapidly, as the concentration exceeds critical micelles concentration, forming a three-dimensional thread like micelles. these thread like micelles usually exhibit shear thinning behavior. after reaching these maximum values of drag reduction, it seems to be degraded as shown in figure 3. this degradation occurs as a result of the break-up of the micelle pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com sahar a. dawood al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 7989 (2017) 83 microstructure because of high shear stresses that exceed critical stress. the decreasing in drag reduction can be also explained if we know that for anionic surfactant the spherical micelles usually aggregate into cylindrical micelles, which formed a network of interlaced rod-like elements, and the aggregation forces of the surfactant molecules are overcome by the shear stress, so the aggregates are broken down to small particles, which have little activity. fig. 5. (a, and b) relation between %dr and q (l/min) for sdbs with different pipe diameters and concentrations. other experiments were done using the two additives mixed with equal concentrations under different shear stresses. the results from these experiments are given in figs. (6a-6b). the maximum drag reduction were (58, and 55) % for concentrations (300, and 200) ppm, respectively, as shown in figure 4a for pipe diameter of 3/4". these percents are higher than that of polymer or surfactant individually. the interaction between surfactant and polymer chain represented by the polymer film, which is formed around surfactant micelles forming aggregate structure. this structure has a drastic effect on the solution rheology. this takes an ordered orientation that minimizes resistance to flow, with increasing flow, they elongated and suppressed the turbulent eddies. hence, the drag reduction increases with shear stress. moreover, it can be seen that there is no significant effect of the 100 ppm concentration of the mixture on the drag reduction. using a pipe diameter of 1", it can be noticed from figure 4b that the best percentage of the drag reduction (58%) is obtained at 200 ppm of the mixture and volumetric flow rate of 7.5 l/min. fig. 6 (a, and b) relation between %dr and q (l/min) for mix with different pipe diameters and concentrations. the surface tension of every fluid is believed to be constant, and the data showed the same result as our expectation. from 50 ppm to 500 ppm, the surface tension of cmc keeps stable around 68 dyne/cm as seen in figure 7, which is because cmc is not surface-active polymer and will not have any effect on surface tension. figure 8 describes the relationship between conductivity pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com sahar a. dawood al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 7989 (2017) 84 and cmc concentration. since the polymer used in the experiments is its sodium salt, sodium carboxyl methyl cellulose (anionic), the conductivity plot has a positive correlation with the concentration [20]. fig.7. surface tension of pure cmc solutions. fig. 8. conductivity of pure cmc solution. the surface tension, and conductivity against concentration of mixing cmc and sdbs solution, are shown in figures 9 & 10. it can be seen that the surface tension for mixture is lower than the pure cmc solution, where the latest is nearly constant about 68 dyne/cm, but the behavior of mixed solution is not constant and as the concentration of solution increases, the surface tension decreases until reaching a point between 200 and 300 ppm, in which the surface tension is constant whenever the concentration increases. this reflects a clear effect of adding a surfactant to the polymer. critical micelle concentration can be specified between 200 and 300 ppm, where at that concentration macromolecular started to be aggregated. fig. 9. surface tension of mixed solution. fig. 10. conductivity of mixed solution. in figure 10, there is a peak in the curve occurred between 200 and 300 ppm concentration of mixed solution . this peak shows a reduction in the conductivity of the mixed solution, as an increase in the mass per unit charge of the material in solution, and this explained as evidence of the formation at that point of micelles from the unassociated molecules of surfactant, with part of the charge of the micelle neutralized by associating counter ions [18,3,4] figure 11 (a-f), show the comparison between the three additives, polymer, surfactant, and the mixture of them and their effects on the drag reduction percent vs. volumetric flow rate with different concentrations and different diameters. pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com sahar a. dawood al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 7989 (2017) 85 fig. 11 (a-f). acomparison between polymer (cmc), surfactant (sdbs), and mixture of them at different pipe diameters and different concentrations. figure 11a shows no significant effect of the 100 ppm concentration of the mixture on the drag reduction, while cmc effect with the same concentration is clear and has a maximum percent drag reduction (62%), this is within pipe diameter 3/4". the same behavior and effects are observed within diameter of (1") for the same concentration (100 ppm); there is no significant effect for mixture and the maximum value of percent drag reduction when using cmc additives is only (52%), as shown in figure 9b. figures (11c & 11e) show a significant effect for the mixture of (200, and 300 ppm) concentration, and the maximum values of percent drag reduction reached (52, and 58) % respectively, within pipe diameter 3/4". almost the same behavior for 200 ppm concentration of the mixture in pipe 1", and concentration 300 ppm is noticed since they have no significant effect, as shown in figures (11d, and 11f), respectively. these results confirmed by the behavior of mixed solution in figures 9 and 10. the effect of reynolds number for the three additives (cmc, sdbs, and mix) within the two pipe diameters and four different concentrations of the friction factor is shown in figures 12a-12f, also these figures gives a comparison with van karman equation and mdr asymptote. this asymptote is dependent solely on the reynolds number, [21 , 22]. it can be seen from these figures that the friction factor decreases with re no. and with concentration, as concentration increases, friction factor decreases. according to some theories, the reduction of the friction coefficient in the turbulent flow of very dilute polymer solutions is due to elongation effects [23]. and more recently [5 , 24] others argue that this could be related to a strong strain-imposed resistance to elongation of the molecules and its effects upon the extensional pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com sahar a. dawood al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 7989 (2017) 86 viscosity of the fluids. thus, the magnitude of the viscosity would be larger than in the absence of such elongational deformations [25]. viscosity is very significant in this research. laminar flow and turbulent flow are two flow regimes in fluid dynamics, when increasing the reynolds number, laminar flow will convert to turbulent flow. in turbulent flow, viscosity is easy to dampen re which means it would be more difficult for a fluid with a higher viscosity to form a turbulent flow. for this reason, viscosity and other rheological properties (shear rate, shear stress, and torque) were determined by using a brookfield viscometer rotating disk (rda) at various concentrations (50, 100, 150, 200, 250, 300, 350, 400, 450, and 500) ppm individually and in the combined form under turbulent conditions at different rotational speeds. fig. (12a-12f) . the relation between friction factor and re no. for cmc polymer solution, sdbs surfactant solution, and their mixture at different pipe diameters and different concentrations. through the figures 12a-12f, friction factor decreases with the increasing of the concentrations of all the three additives used, and with re no. comparing with von karman equation and mdr asymptote, good results are obtained for friction factors for cmc, sdbs, and their mixture solutions flowing through 3/4" pipe diameter and four different concentrations, these values of (f) located between von karman equation and mdr asymptote, it means a good agreement with them. a pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com sahar a. dawood al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 7989 (2017) 87 fig. 13. shear stress vs. shear rate for mixed solution, fig. 14. viscosity vs. shear rate for mixed solution. the effect of shear rate on shear stress for mixture solution at different concentrations is shown in figure13. this figure indicates that the shear viscosity increases with the concentration of cmc solution. at the same rotational speed, higher cmc concentration solution exhibits a higher apparent viscosity. also, with increasing the shear rate, the apparent viscosities showed an increasing trend, which means cmc mixture solutions are shear-thickening fluids (figure 14). 5. conclusions this research leads to the conclusion that a good drag reduction behavior of the three additives (cmc polymer, sdbs surfactant, and their mixture) was carried out in turbulent pipe flow (diameter 3/4"). it could also be concluded from this work that using a mix of polymer and surfactant resulted in a higher drag reduction (5862) % than that using polymer or surfactant alone. the drag reduction increases with increasing additive concentration. the drag reduction of the mix additives showed more stable form among degradations due to the complexity of the aggregate structure that formed from the interaction between polymer and surfactant. low different concentrations were used and their effect were relatively uneven, but on the whole the percentage of drag reduction increases with the increasing of the concentration for the three kinds of additives used. but still this work needs to be completed by using higher concentration for polymer and surfactant, studying behavior of these higher concentrations on drag reduction percent, to make a comparison between low concentrations and higher concentrations and which of them is preferable. 6. references [1] goddard, e. d., "polymer—surfactant interaction part ii polymer and surfactant of opposite charge", colloids and surfaces, 19 (23), pp. 301-329, 1986. [2] hayder, a.b, zainab yousif, zulkefli b. y, edward o., " effect of sdbs on the drag reduction characteristics of polyacrylamide in a rotating disk apparatus"; international journal of basic and applied sciences, 4 (3), pp. 326-332, 2015. [3] ketan, p., "interactions between drag reducing polymers and surfactants" msc. thesis, university of waterloo, ontario, canada, 2009. [4] anosh, m., "achieving drag reduction, though polymersurfactant interaction", msc. thesis, university of waterloo, ontario, canada, 2013. [5] trabelsi, s., raspaud, e. and langevin, d., "aggregate formation in aqueous solutions of carboxymethylcellulose and cationic surfactants", langmuir, 23(20), pp. 1005310062, 2007. [6] goddard, e. d.and ananthapadmanabhan, k., "interactions of surfactants with polymers and proteins", crc press, boca raton, 1993. [7] serife, z. v, goknur, b and yusuf, u., "experimental investigation of drag reduction effects of polymer additives on turbulent pipe flow using ultrasound doppler velocimetry" turkish journal of chemistry, 38, pp. 142-151, 2014. [8] subbarao, c. v, divya, p., appala naidu, d. and king, p., "drag reduction by anionic surfactant solutions in gravity driven flow system", iran. j. chem. eng. vol. 32, no. 1, 2013. [9] toms, b. a., “some observation on the flow of linear polymer solutions through straight pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com sahar a. dawood al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 7989 (2017) 88 tubes at large reynolds number", proceedings of the first international congress of rheology”, north holland, amsterdam, 2, pp, 135-141, 1949. [10] w. brostow, “drag reduction in flow: review of applications, mechanism and prediction,” j. ind. eng. chem., vol. 14, no. 4, pp. 409–416, jul. 2008. [11] katepalli. r. sreenivasan and christopher m. white, “the onset of drag reduction by dilute polymer additives, and the maximum drag reduction asymptote”, j. fluid mech., 409, pp. 149-164, 2000. [12] yongning , b., li yu., and jing ren, " the drag reduction effects of anon-newtonian fluid (cmc aqueous solution) in a sinusoidal wavywalled tube at moderate reynolds numbers for steady flow", 3rd international conference on material, technical and manufacturing engineering (1c3me 2015). [13] saeki, takashi., "flow properties and heat transfer of drag-reducing surfactant solutions", developments in heat transfer, 2011. [14] s. kim, "turbulent drag reduction behavior of pseudoplastic fluids in straight pipes", thesis (ph. d.)--university of waterloo, 2003. [15] lumley j. l., “drag reduction by additives”, ann. rev. fluid mech., 1, 367, 1969. [16] landahal, m.t., “drag reduction by polymer addition”, proc 13th iutam congr. (ed. e. becher & g. r. mikhailov), springer, 1973a. [17] missel, p.j., et al., "influence of chain length on the sphere-to-rod transition in alkyl sulfate micelles", the journal of physical chemistry, 87(7), pp. 1264-1277, 1983. [18] elson, t. and j. garside, "drag reduction in aqueous cationic soap solutions" journal of non-newtonian fluid mechanics, 12(2), pp.121-133, 1983. [19] rosen. and milton, j., " surfactants and interfacial phenomena", hoboken, nj, usa. john wiley & sons, inc., pp. 105, 2004. [20] jia yang, "investigations on drag reduction by interactions between polymer and surfactant and polymer and polymer", msc. thesis, waterloo, ontario, canada, 2015. [21] hartnett, j. p., "viscoelastic fluids: a new challenge in heat transfer", trains. asme: j. heat transfer 114 , 296, 1992. [22] zakin, j., myska, j. and chara, z., "new limiting drag reduction and velocity profile asymptotes for nonpolymeric additive systems", aiche journal, 42 (12), pp. 35443546, 1996. [23] hinch, e. j., "mechanical models of dilute polymer solutions in strong flows", phys. fluids 20 , s22, 1977. [24] anees, a. k, and ali, a. a, "performance of polyacrylamide as drag reduction polymer of crude petroleum flow", ainshams engineering journal, 5, pp. 861-865, 2014. [25] hoyt, j. w., “turbulent flow of drag reducing suspensions”, naval undersea centre rep. nuc tp 299, 1972. pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com )2017( 79-89 صفحة ،2العدد ،13المجلد الھندسیة الخوارزمي جلةم ي داوود سحر عبد الھاد 89 دراسة خصائص امكانیة مزج بولیمر مع مواد تقلیل الشد اسطحي وتاثیرھا على ظاھرة تقلیل االحتكاك باستخدام نظام انابیب جریان ھادي داوودلسحر عبد ا الجامعة التكنولوجیة /قسم الھندسة الكیمیاویة sahar_abd60@yahoo.com: لبرید االلكترونيا الخالصة محالیل مائیة على ظاھرة تقلیل أألعاقة بوصفھا وصودیوم دودسیل بنزین سلفونیت ، راسة تأثیر استخدام كاربوكسیل مثیل سلیلوزفي ھذا البحث تم د ) جزء من الملیون ٥٠٠، ٤٥٠، ٤٠٠، ٣٥٠، ٣٠٠، ٢٥٠، ٢٠٠، ١٥٠، ١٠٠، ٥٠( تراكیز مختلفة من ھذه المواد مثل . خالل االنابیبمن لجریان السوائل لكل من " واللزوجة، التوصیلیة الكھربائیة، الشد السطحي"ھا لتحلیل خواص ھذه المحالیل المحضرة باستخدام ھذه المضافات والتي تشمل تم استخدام من خواص المحالیل ) جزء من الملیون ٣٠٠، ٢٠٠، 50١٠٠, ( تراكیز مثل ةافضل اربع. المضافات المستخدمة منفصلة و ممزوجة وبتراكیز مختلفة لدراسة ) انج ٣/٤، انج ١(مختلفة االقطار (pvc)أستخدمت انابیب ،المدروسة تم استخدامھا لدراسة تأثیرھا على ظاھرة تقلیل أألعاقة لجریان السوائل ة المزج واعطت نسبة النتائج أوضحت امكانی. مواد مقللة لالحتكاك عند جریان السوائل خالل ھذه االنابیببوصفھا تاثیر ھذه المضافات منفصلة وممزوجة mdrتناقص معامل االحتكاك مع تزاید عدد رینولدز و توافق جید مع معادلة فون كارامن و ، اعلى مما لو استخدمت منفصلة % ٥٨تقلیل اعاقة حوالي asymptote .حرج لتكوین المذیالت وبدایة ظاھرة عوامل مؤثرة وقد تم مناقشة كل من التركیز ال دقطر االنابیب تركیز المضافات كلھا تع، عدد رینولدز . تقلیل االعاقة والتداخالت بین المضافات الممزوجة pdf created with pdffactory trial version www.pdffactory.com mailto:sahar_abd60@yahoo.com http://www.pdffactory.com http://www.pdffactory.com (microsoft word \307\316\341\307\325 \346\321\323\341) al-khwarizmi engineering journal al-khwarizmi engineering journal,vol. 13, no. 3, p.p. 3845 (2017) implementation of transmitter zigbee system based on wireless sensor network of ieee 802.15.4 standard ekhlas k. hamza* russul h. hadi** *,**department of control and systems engineering / university of technology *email: ekhlas_kadhum@yahoo.com ** email: russulh@gmail.com (received 6 december 2016; accepted 29 march 2017) https://doi.org/10.22153/kej.2017.03.002 abstract zigbee is considered to be one of the wireless sensor networks (wsns) designed for short-range communications applications. it follows ieee 802.15.4 specifications that aim to design networks with lowest cost and power consuming in addition to the minimum possible data rate. in this paper, a transmitter zigbee system is designed based on phy layer specifications of this standard. the modulation technique applied in this design is the offset quadrature phase shift keying (oqpsk) with half sine pulse-shaping for achieving a minimum possible amount of phase transitions. in addition, the applied spreading technique is direct sequence spread spectrum (dsss) technique, which has the effect in getting better performance for the transmitter system in multipath environments. the system is developed through the use of matlab/simulink to show the performance of the proposed system in response to the appliy modulation technique. keywords: dsss technique, ieee 802.15.4, msk, oqpsk, zigbee. 1. introduction short-range networks are classified into two categories. the first one is wireless local area networks (wlans), an extension to wired-local area networks (lans), and the second is wireless personal area networks (wpans) that are also called as wireless sensor networks (wsns). figure 1 shows some of the properties included in those two categories [1]. although infrared, wlan, and bluetooth have been extensively used as near field wireless communication technologies, they have some drawbacks, including difficulty and complexity in design and installation processes, the large amount of wasted power, short coverage area, and suitable only for small-scale networking. in contrast, wsns have a greater role in solving the inconvenience into people’s lives. they have many features unlike wired-network, such as suitable organizing of the network, less affectation by surrounding environment, low-cost and low power consumption [2]. the low rate wireless personal area networks (lr-wpans) include two types of devices that are fully functional devices (ffd) and devices with reduced functionality (rfd). the first type could be utilized as a device, a pan coordinator, or a coordinator, while the second could be used as a device only [3]. this paper is organized as follows. ieee 802.15.4 and zigbee architecture are presented in section 2. section 3 introduces an overview of digital modulation techniques. in section 4,the proposed model is demonstrated. simulation and design results are depicted in section 5. finally, section 6 includes research conclusions. ekhlas k. hamza al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 3845(2017) 39 2. ieee 802.15.4 and zigbee architecture ieee 802.15.4 standard identifies specifications of both of physical layer (phy) and medium access control (mac) sub layer for lrwpans. it also includes extended layers for wpans and wlans. figure 2 shows the architecture of zigbee technology as an lrwpan [4]. zigbee technology can be worked at three various frequency bands according to the geographical coverage area. in europe, 868-868.6 mhz (868 mhz) is used, in northern america 902-928 mhz (915 mhz), while the 2.4 ghz is used all over the world, and it depends on unlicensed industrial, scientific and medical(ism) radio bands [5]. fig. 1. classes of short-range wireless network. 3. overview of digital modulation techniques fig. 2. zigbee technology architecture. the process that effects on a digital symbol in order to convert it into a signal suitable for transmission is called digital modulation [6]. this process involves the use of various digital modulation techniques that are different in certain parameters. varying signal amplitude, frequency or phase could be done to obtain some of these techniques. furthermore, hybrid techniques could be driven from hybrid variations of these parameters [7]. figure 3 illustrates the classification of digital modulation techniques [8]. in this paper, offset quadrature phase shift keying (oqpsk), also called staggered qpsk (sqpsk), modulation technique is applied, which is the modified version of qpsk. the benefit behind this modification is to delay the signal bya half cycle so as to avoid possible change in signal phase. the carrier permits to send the signal for four possible orthogonal phases and as shown in figure 4 [6] [9] [10] [11]. ekhlas k. hamza al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 3845 (2017) 40 fig. 3. types of digital modulation. fig. 4. constellation plot of qpsk and oqpsk. in oqpsk, just like qpsk, the data stream mk (t) = m0, m1, m2, ..., is divided into two channels: in-phase and quadrature. in-phase channel represents the even bit streams of data mi (t) = m0, m2, m4. . ., while mq(t) = m1,m3,m5, . .., represents the odd bit streams for quadrature channel that are staggered by only one bit period (half a symbol period) and this is depicted in figure 5. oqpsk waveform is shown in figure 6 which clarifies that the phase shift does not exceed ±90◦ hence; the waveform envelope will be limited as it will not go to zero as it does with qpsk [12]. in addition, symbol interference effect caused by limited transmitted band and non-linear behavior of the used amplifier could be reduced[6]. for further enhancements, it is possible to reduce phase changes to produce a smoother signal that could behave as completely continuous. one type of continuous phase frequency shift keying (cpfsk) is a minimumshift keying (msk) modulation technique. msk could be produced from oqpsk by shaping the pulses with half sine wave, or can be driven as a special case of cpfsk. as compared with qpsk or oqpsk, the msk modulation technique has some features, including constant envelop of transmitted signal and continuous phase (no sudden phase changes) [6][13]. fig. 5. staggering of the in-phase and quadrature modulated bit streams in oqpsk. fig. 6.oqpsk waveform. fig. 7. msk modulation. digital amplitude shift keying (ask) frequency shift keying (fsk) phase shift keying (psk) quadrature amplitude modulation ekhlas k. hamza al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 3845(2017) 41 4. proposed model this paper focuses on implementing a zigbee transmitter system using (phy) layer specifications of ieee 802.15.4 standard, and according to the features illustrated in table 1. table 1, specifications of 2.4 ghz zigbee transmitter under ieee 802.15.4 standard features value data rate 250kbps frequency of operation 2.4ghz number of channels 16 channel spacing 5mhz chip rate 2mbps pulse shaping half sine spreading technique dsss modulation technique oqpsk the system is designed using matlab/simulink, where the basic components of the proposed model are illustrated in figure 8. the following steps describe the design procedure in more details: step1: preparing of input bit stream this step includes applying mapping process of bit to symbol and symbol to chip. at first, the input data stream must be prepared to meet ieee 802.15.4 specifications consider data rate and chip rate. in this design, random input generator from matlab/simulink toolbox is used as a source of data stream, and it has been adjusted to operate on 250kbps. pseudo-random noise (pn) chip sequence is used to construct a direct sequence spread spectrum (dsss). the reason behind the use of this technique is to increase the frequency of input data stream to 2 mbps which in turn might improve transmitter performance in multi path environment. it is also used to achieve an improvement in signal to noise ratio (snr) throughout increasing resistance of the system towards anticipated or accidental jamming ]٥ [. 32-bit chip sequence is generated at 2mbps by pn sequence generator. multiplying input data stream by a pn sequence after converting them into nrz format produces dsss output signal. step2: serial to parallel conversion prior to modulation process, the previous coded data are separated into in-phase and quadrature data according to the scheme shown in figure 9. even and odd clock pulses are generated by jk-flip flop in toggle state and with clock frequency equals to 2mhz. the positive output q is used as a source of clock pulses for the first dflip flop to produce the in-phase data with 1mhz, while the negative output is fed to the second dflip flop producing quadrate data. fig. 8. proposed model. fig. 9. serial to parallel conversion ekhlas k. hamza al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 3845 (2017) 42 step 3: modulation process oqpsk modulation is the same as qpsk except the q-channel is delayed by t/2 seconds. although the power density and error performance are the same in the two techniques, oqpsk produces a maximum phase change of π/2 in contrast to qpsk which provides a phase shift of π [12]. the function of oqpsk signal for the modulator part can be written as [6]: ���� = � √2 i�t� cos 2��� � − � √2 q �t − � 2� sin 2��� �, −∞ < � < ∞ ...(1) where �is the amplitude, ��is the center frequency, i�t� is the in-phase component, and q �t − � �� is the shifted quadrature component of the signal. the output of in-phase and quadrature data is firstly multiplied by half sine wave of 1mhz to perform pulse shaping. the purpose behind the use of pulse shaping (also called premodulating filter) is to make the transmitted signal spectrum getting matched with channel bandwidth, hence; avoiding multipath and intersymbol interference (isi) effects [5].in this design, half sine pulses are generated by multiplying sine wave having a frequency of 0.5 mhz with train of pulses at 0.5 mhz. in order to achieve synchronization state between in-phase and quadrature data, a delay is added after the generated half sine pulses in i-channel. the function of half sine pulse signal can be written as [11]: p�t� = sin �� � ! ...(2) after half sine pulse shaping, the i-channel data are multiplied by a sine wave of 2.4 ghz and the q-channel data is multiplied by a cosine wave at the same frequency. the final modulated transmitted signal is obtained by adding the output of i-channel and q-channel. the simulated system is illustrated in figure 10. fig. 10. zigbee transmitter with oqpsk modulation and half sine pulse-shaping. 5. simulation results the proposed model has been implemented using matlab/simulink to show system performance at each point of simulation where the following results have been gotten. the input bit stream has been produced by a random input generator with data rate of 250 kbps as shown in figure 11. fig. 11. input data stream. after generating input sequence, it has been multiplied by a pn sequence of 32 chips and chip rate of 2mbps to produce a dsss signal. figures 12 and 13 depict the pn sequence and input data after applying spreading technique respectively. ekhlas k. hamza al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 3845(2017) 43 fig. 12. the output signal pn sequence generator. fig. 13. input data after applying dsss technique. the resulted signal is divided into even and odd part to produce the in-phase and quadrature data by serial to parallel conversion and as shown in figure 14 and 15 respectively. fig. 14. even and odd pulses. fig. 15. in-phase and quadrature data. the output data from in-phase and quadrature channel are converted into nrz format and then multiplied by a half sine wave. the figures below show the generation of half sine pulses and the output of each channel after employing this pulseshaping method. fig. 16. half sine pulse-shaping. fig. 17. in-phase data after half sine pulseshaping. fig. 18. quadrature data after half sine pulse shaping. figures 19 and 20 shows the output signal of in-phase and quadrature channel after the modulation process; while the final output signal of zigbee transmitter is depicted in figure 21. fig. 19. in-phase data after modulation. fig. 20. quadrature data after modulation. fig. 21. transmitted signal of proposed zigbee transmitter. ekhlas k. hamza al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 3845 (2017) 44 6. conclusions in this paper, 2.4 ghz zigbee transmitter system is designed and simulated using matlab/simulink to demonstrate the possible performance under ieee 802.15.4specifications. the system has been designed indirectly from scratch using oqpsk modulation technique with half sine pulse-shaping method. the result of simulation has shown that the waveform of the final signal was almost like minimum shift keying (msk) modulator by assuring only a small amount of phase transitions (approximately less than 90◦) because of the pulse-shaping. also, the use of direct sequence spread spectrum technique has the effect of further reducing the interference effects. 7. references [1] s. farahani, zigbee wireless networks and transceivers: newnes, 2011. [2] n. a. somani and y. patel, "zigbee: a low power wireless technology for industrial applications," international journal of control theory and computer modelling (ijctcm), vol. 2, pp. 27-33, may 2012. [3] i. m. el emary and s. ramakrishnan, wireless sensor networks: from theory to applications: crc press, 2013. [4] c. wang, t. jiang, and q. zhang, zigbee® network protocols and applications: crc press, 2014. [5] k. gorantla and v. mani, "simulink model for zigbee transceiver using oqpsk modulation under fading channels," ieee international conference in communications and signal processing (iccsp), pp. 0220-0224, 2015. [6] f. xiong, digital modulation techniques: artech house, 2006. [7] d.k.sharma, a.mishra and rajiv savena “analog & digital modulation techniques: an overview”, international journal of computer science and communicationtechnologies, vol. no. 3, pp. 551-555, 2010. [8] f. quadri and a. d. tete, “fpga implementation of digital modulation techniques,” ieee international conference in communications and signal processing (iccsp), melmaruvathur, india, pp. 913-917, 2013. [9] r. ahmad, o. sidek, w. m. h. w. hassin, and s. k. k. mohd, "implementation of ieee 802.15. 4-based oqpskpulse-shaping block on fpga," ieee international conference in computer applications and industrial electronics (lccaie), pp. 459-464, 2011. [10] p. mishra and s. mane, "implementation of qpsk modulation on matlab simulation," international journal of engineering and innovative technology (ijeit), volume 5, issue 8, 2016 [11] r. kanna, “design of zigbee transceiver for ieee 802.15.4 using matlab/simulink,” master thesis, dept. elec. comm. eng., national institute of technology, india, 2011. [12] s. k. kaul, "qpsk, oqpsk, cpm probability of error for awgn and flat fading channels," wireless communication technologies, 2005. [13] w. y. yang, y. s. cho, w. g. jeon, j. w. lee, j. k. kim, j. h. paik, m. h. lee, k. i. lee, k. w. park and k. s. woo, “matlab/simulink for digital communication”, a-jin publishing , 2009. [14] c. c. wang, j. m. huang, l. h. lee, s. h. wang, and c. p. li, "a low-power 2.45 ghz zigbee transceiver for wearable personal medical devices in wpan," digest of technical papers, international conference on consumer electronics, pp. 1-2, 2007. [15] m. b. mantri, p. velagapudi, b. c. eravatri, and v. v. mani “performance analysis of 2.4ghz ieee 802.15.4 phy under various fading channels,” ieee international conference in emerging trends in communication, control, signal processing computing applications (c2spca), pp.1-4, 2013. [16] k. d. jha and m. k. srivastava, "design & simulation of zigbee transceiver system based on msk and qpsk using matlab," international journal of new trends in electronics and communication (ijntec), vol.4, issue. 1, pp. 5-9, 2013. ekhlas k. hamza al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 3845(2017) الخاص بشبكات المستشعر ieee 802.5.4 باألعتماد على معيار zigbeeتمثيل نظام إرسال الالسلكي **رسل هيثم هادي *حمزة اخالص كاظم ةقسم هندسة السيطرة والنظم/ الجامعة التكنولوجي **،* ekhlas_kadhum@yahoo.comالبريد األلكتروني: * russulh@gmail.comالبريد األلكتروني:** الخالصة في مواصفات تصميمه على معيار zigbeeاحد شبكات المستشعر الالسلكي والذي ُصِمَم لمالئمة التطبيقات ذات المدى القصير. يعتمد zigbeeيعد ieee 802.15.4 تم تصميم ،والذي يهدف الى تصميم شبكات بتكلفة وقدرة استهالك واطئتين باألضافة الى اقل معدل ممكن ألرسال البينات. في هذا البحث مع تشكيل نبضات oqpsk)الخاصة بالمعيار المذكور حيث تم استخدام ( (phy layer)باإلعتماد على خصائص الـ zigbeeنظام إرسال لمتحسس لغرض تحسين مستوى اداء النظام dsss) تقنية ( فضالً عنكتقنية تضمين كونها تضمن حدوث تَغيُر طفيف في إنتقال الطور للموجة المرسلة نصف جيبية بقة.لبيان األداء بالنسبة لتقنية التضمين المط matlab/simulinkفي البيئات متعددة القنوات. تم تمثيل التصميم المقترح للنظام باستخدام برنامج (microsoft word 7483 \335\321\314 \343\315\341) al-khwarizmi engineering journal,vol. 13, no. 1, p.p. mechanical properties investigation different parameters variations department of electromechanical (received 30 may 2016; accepted 7 september 2016) https://doi.org/10.22153/kej.2017.09.001 abstract the main objective of this research is to light unman air vehicle (uav). the mechanical properties, weight and cost are the basis criteria of fiber volume fraction, fillers and type of fiber selection. finite element method was used to investigate the stress distribution on addition to estimate the maximum stress. an experiments plan has been designed to get the data on the basis of taguchi technique. the most effective parameters at noise ratio (s/n), main effect and analysis predicted results are very close. it was found that t followed by filler content and then the fiber volume fraction roving + unidirectional carbon) fiber, 7.5% good mechanical properties, high safety factor, acceptable cost, and offers weight savings on average by 40% percent as compared to aluminum alloy. keywords: mechanical properties, composite material, 1. introduction in aero engineering applications, the to weight ratio and cost are the main factor influence the selection of material [1,2]. composite materials are well known excellent combination of high structural stiffness and low weight [3,4]. nowadays, the vehicle (uav) air frame use 70% composite materials. whereas boeing 787 composite materials in airframe and primary structure. this approach offers weight savings compared with the conventional aluminum designs [5]. composites material are composed of fibers and matrix. the main source of strength and reinforcement is fibers, while matrix hold the fibers together in shape with the of stresses transfer between the fibers prevent formation of new surface flaws and khwarizmi engineering journal,vol. 13, no. 1, p.p. 7483 (2017) properties investigation of composite material under different parameters variations farag m. mohammed electromechanical engineering/ universityof technology email: drfaragmahel@yahoo.com (received 30 may 2016; accepted 7 september 2016) https://doi.org/10.22153/kej.2017.09.001 is to design and select a composite plate to be used in fabricating the mechanical properties, weight and cost are the basis criteria of fiber volume fraction, fillers and type of fiber with three levels for each were considered to optimize the composite plate inite element method was used to investigate the stress distribution on the wing at cruise an experiments plan has been designed to get the data on the basis of taguchi at the process to be find out by employing l9 (3 3 ) orthogonal array nalysis of variance (anova). the results show that, the experimental was found that the type of fiber is the most effective parameter on the plate selection fiber volume fraction. the best parameters combinations are 7.5% graphite filler and 30% fiber volume fraction). this combination provides , high safety factor, acceptable cost, and offers weight savings on average by 40% percent as echanical properties, composite material, polyester, taguchi technique. s, the strength the main factors influence the selection of material [1,2]. composite materials are well known for their combination of high structural stiffness he unman air vehicle (uav) air frame use 70% composite boeing 787 use 50% composite materials in airframe and primary offers weight savings as conventional aluminum are composed of he main source of strength matrix make with the ability between the fibers [6]. matrix of new surface flaws and abrasion by isolates the fibers from one another able to deform under applied load stress [7]. matrix holds fibers required shape, but the fibers improves mechanical properties. qahtan [8 physical and mechanical properties of materials polymer matrix with10% weight fraction. it is found that, the fraction effects on the properties of composite materials. monika et al [9] had result presents that the failure of the tension specimens happens at the ends of section and the curved region begins whereas, farag and drai [10], mechanical and tribological behavior of glass polyester composite system under the effect graphite filler contents. it was found graphite filler content increases al-khwarizmi engineering journal composite material under in fabricating wing skins of the mechanical properties, weight and cost are the basis criteria of this selection. the to optimize the composite plate at cruise flight condition in an experiments plan has been designed to get the data on the basis of taguchi orthogonal array, signal to he experimental and the on the plate selection, parameters combinations are ((e-glass woven . this combination provides , high safety factor, acceptable cost, and offers weight savings on average by 40% percent as abrasion by isolates the fibers from one another, able to deform under applied load and distributive fibers to maintain the improves the matrix 8] investigated the physical and mechanical properties of composite materials polymer matrix with10% weight the particle volume properties of composite had an experimental the failure of the tension ends of straight gage region begins transition. demonstrated the mechanical and tribological behavior of glassunder the effect of was found that with the increases up to 7.5%. the farag m. mohammed al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 7483(2017) 75 mechanical and tribological properties behavior improved. since, the mechanical properties, weight and cost are the main parameters that effect on the composite material selection. taguchi technique and multiple regression models can be used to optimize these parameters. drai et al [11] using taguchi approach to investigate the mechanical and tribological behavior of glass-polyester composite material under different filler content. it is found that the additives parameter have the highest influence. farag, drai and hussam [12], demonstrate the influence of graphite filler content on the sandwich panel glass-polyester deflection and deformation behavior subjected to low velocity impact by using taguchi technique, and show that the mass has the main influence on the deflection, whereas the graphite filler is the dominate parameter influence on the deformation. taguchi method is a powerful tool to design a high quality system and has been widely used in engineering analysis. moreover, taguchi method uses a special design of orthogonal array to demonstrate the entire parameters effects through a small number of experiments. therefore, the time required for the experimental investigations is significantly reduced, and it is effective in the investigation of the multiple factors effect on the performance, as well as to study the influence of individual factors to determine which factor has more influence, which one less [13,14,15]. the main objective of this work is to design and select a composite plate to be used in fabricating wing skins of a light uav. to investigate the influence of fiber volume fraction, filler and type of fibers on the composite plate selection parameters. an experiments plan has been designed to get the data on the basis of taguchi technique in a controlled way. 2. unman air vehicle specifications the uav is a small short range tactical vehicle which is used for reconnaissance and surveillance missions. it operates in iraq weather. designed with high aspect ratio wing, twin tail boom layout and a 3 hp power engine. equipped with auto-pilot system and it can flight fully autonomous with the programmed flight track. the uav specifications are shown in table.1. table 1, specification of uav. length 2 m wingspan 3 m airfoil naca 0012 chord 0.35 m height 1.25 m maximum speed 100 km/h cruise speed 50-60 km/h ceiling 1000 m maximum range 50 km max takeoff weight 30 kg navigation mode gps 3. experimental test material: materials used are resin, fiber, filler and a hardener (methyl ethyl kenton peroxide) at room temperature. resin is unsaturated polyester (up). fibers are; e-glass woven roving (eg) and unidirectional carbon (uc). fillers are graphite (g) and aluminum (al) powders. the physical and mechanical properties for these raw materials are listed in tables 2, 3 and 4. table 2, physical and mechanical properties of (up) resin [16]. properties value density 1268 kg/m 3 tensile strength 50 mpa modulus of elasticity 3 gpa elongation 2.5% barcol hardness 40 table 3, physical and mechanical properties of fiber: ae-glass woven roving [17]. properties value density 2580 kg/m 3 tensile strength 3450 mpa modulus of elasticity 72 gpa poisson’s ratio 0.22 bunidirectional carbon [18]. properties value density 1790 kg/m 3 tensile strength 3900 mpa modulus of elasticity 230 gpa poisson’s ratio 0.2 farag m. mohammed al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 7483(2017) 76 table 4, physical and mechanical properties of filler: aaluminum powder [19]. properties value density 2700 kg/m 3 tensile strength 60 mpa modulus of elasticity 71 gpa thermal conductivity 247 w/m.̊c practical size 75 µm bgraphite powder [19]. properties value density 1780 kg/m 3 tensile strength 40 mpa modulus of elasticity 11.7 gpa thermal conductivity 118 w/m.k practical size 100 µm experimental design: three parameters that (fiber volume fraction, filler and type of fiber) were considered with three levels for each, to optimize the composite plate mechanical properties, cost and weight. table 5 shows these parameters with their levels. taguchi technique to experimentation gives a regular way to collect data, interpret and analyze to satisfy the study objective. selection of control factors is the most important stage in the experiment design. therefore, take care in choosing a suitable orthogonal array and control parameters with their levels, to get combination of optimum level [20, 21]. to study the impact of parameters in this work, l9 (3 3) orthogonal design has been used as shown in table 6. specimens preparation: specimens were manufactured by dry hand layup technique. unsaturated polyester resin was mixed with the hardener in ratio 100:2 by weight. the powders filler was mixed with known amounts of unsaturated polyester resin. the stacking procedure of fiber-polyester composites was constructed by placing fiber ply one above other with resin mixed well to spread between plies using mold of (250x250x20) mm. the fiber orientation of unidirectional carbon was made with [0/90/0/90], whereas for (eg+uc) was made by [eg/0uc/eg/90uc]. the whole assembly was pressed by (0.3 mpa) then released and allowed to cure for a 6 days at room temperature. the product is a composite plate. the plates are cut into the appropriate dimensions using a tipped cutter, and then machining it by using a vertical milling cnc machine to manufacture a tensile tests specimens according to astm d 638-3 [22]. while, charpy impact test specimens were performed according to iso 179 [23] as shown in fig.1. these specimen’s details are shown in table 6. tensile test done using laryee tensile test machine, with 1000 kg applied load and (2mm/min) strain rate. while, impact test done using laryee charpy impact test machine. tests carry out in laboratory of material eng. dept./university of technology. -a -b fig. 1. experimental test specimens: atensile test specimens. b charpy impact test specimens. table 5, parameters with their levels. parameters symbol levels of parameter level1 level2 level3 type of fiber a eg uc eg+uc filler b 0% 5%al 7.5%g fiber volume fraction c 27% 30% 33% farag m. mohammed al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 7483(2017) 77 table 6, experimental plan using orthogonal array l9. exp. no. parameters and level type of fibera fillerb fiber volume fraction c level value level value level value 1 1 eg 1 0% 1 27% 2 1 eg 2 5%al 2 30% 3 1 eg 3 7.5%g 3 33% 4 2 uc 1 0% 2 30% 5 2 uc 2 5%al 3 33% 6 2 uc 3 7.5%g 1 27% 7 3 eg+uc 1 0% 3 33% 8 3 eg+uc 2 5%al 1 27% 9 3 eg+uc 3 7.5%g 2 30% 4. results and discussion aerodynamic forces: the aerodynamic loading under the cruise flight conditions can simply be defined as, the load acting on the aircraft will be equivalent to the weight of the structure. lift load on the aircraft structure is normally distributed as 80% on wings and remaining 20% on the fuselage [24]. since, the aircraft take-off weight under design is 30kg. therefore, the total load acting on the wings will be equal to (300 × 0.8 = 240n). the load acting on each wing will be 120n. since, the aerodynamic load is applying on the center of pressure of wing located at ¼ chord from leading edge. using finite element method (ansys-11 software) to investigate the effect of (120n) on the wing. the results represent the von misses stress distribution shown in fig. 2, and it is found that the maximum stress is 40 mpa. experiment results: after preparing all the nine specimens for each test. experimental tests were conducted use tensile test machine and charpy impact test machine. each experiment was repeated three times and then compute the average value. the modulus of elasticity, fracture toughness, and tensile strength are the mechanical properties that investigated here. the experimental results for each specimen with their calculated density was listed in table 7. the density of a composite material can be calculated using [25]. ρc = ∑ vi ρi = v1.ρ1 + v2.ρ2 + … + vn. ρn …(1) where: ρc: density of composite material. ρ1, ρ2, ρn: density of each constituent. v1, v2, vn: volume fraction of each constituent. fig. 2. von misses stress distribution on wing. farag m. mohammed al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 7483(2017) 78 table 7, experimental results and their signal-to-noise ratio. exp. no. modulus of elasticity tensile strength toughness density gpa s/n db mpa s/n db mpa√m s/n db kg/m 3 s/n db 1 2.612 8.339 129 42.212 16.570 24.386 1622.24 -64.202 2 5.201 14.322 174.53 44.837 19.633 25.860 1733.2 -64.777 3 8.340 18.423 201.40 46.081 21.456 26.631 1739.36 -64.808 4 14.373 23.151 315.21 49.972 26.750 28.546 1424.6 -63.074 5 23.639 27.473 480.49 53.634 32.192 30.155 1511.86 -63.590 6 24.401 27.748 500.84 53.994 34.047 30.642 1447.34 -63.211 7 14.425 23.182 240.74 47.631 20.892 26.400 1570.61 -63.921 8 12.247 21.761 357.24 51.059 26.306 28.401 1587.19 -64.013 9 16.307 24.247 467.32 53.392 30.146 29.585 1581.5 -63.981 signal to noise ratio (s/n): signal to noise ratio measures sensitivity of the quality investigated to those uncontrollable factors (error) in the experiment. using “bigger is better” quality characteristic for mechanical properties investigation, while “smaller is better” used for density analysis to get high strength/weight ratio. the following logarithmic equation used to perform s/n ratio analysis [26]. 1. “bigger is better”, �⁄ = −10 ����� �1�� 1��� � ��� � … 2" 2. “smaller is better”, �⁄ = −10 ����� �1����� � ��� � … 3" where: n is the observations number. yi is the data observed. for all nine experiment readings, the s/n ratios were calculated and listed in table 7. from table 7, it can be seen that, experiment number 6 has the largest mechanical properties s/n ratio. the parameters combination with their level in this experiment is a2b3c1. whereas experiment number 4 show the smallest density value, and the parameters combination with their level is a2b1c2. according to the results of combinations generated from orthogonal array. the optimum levels were predicted by estimating the control factors for different three levels. the control factors levels were determined and listed in table 8. fig. 3 shows the distributions of average s/n ratios. where the goal for mechanical properties is “bigger is better”, from fig. 3 it can be noticed that, the optimal parameters combination with their levels is a2b3c3, equivalent to (carbon fiber, 7.5%g filler and 33% fiber volume fraction), which get a higher characteristic of modulus of elasticity, tensile strength and toughness. while a2b1c1 is the optimal parameters combination with their levels for density to get “smaller is better”, that equivalent to (carbon fiber, 0% filler and 27% fiber volume fraction). table 8, average signal to noise ratio of different parameter levels. parameter symbol average of s/n (db) of different parameter levels max min optimum level level 1 level 2 level 3 modulus of elasticity type of fiber a 13.6948 26.1239 23.0635 12.4291 a2b3c3 filler b 18.2242 21.1850 23.4730 5.2487 fiber volume fraction c 19.2827 20.5734 23.0261 3.7433 farag m. mohammed al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 7483(2017) 79 tensile strength type of fiber a 44.3768 52.5332 50.6942 8.1564 a2b3c3 filler b 46.6049 49.8434 51.1558 4.5509 fiber volume fraction c 49.0883 49.4006 50.1153 0.3122 toughness type of fiber a 25.6257 29.7810 28.1284 11.7167 a2b3c3 filler b 26.4442 28.1386 28.9524 4.2933 fiber volume fraction c 27.8097 27.9969 28.0185 1.3471 density type of fiber a -64.5957 -63.2918 -63.9718 11.7167 a2b1c1 filler b -63.7325 -64.1266 -64.0002 4.2933 fiber volume fraction c -63.8088 -63.9441 -64.1065 1.3471 underlined value represents the optimum level. fig. 3. main effect graph. analysis of variance (anova): anova is a statistical method in which used for predicting the individual interactions of all control parameters. in this research, anova used to analyze the influence of fiber volume fraction, filler and type of fiber on the mechanical properties and density of composite material plates. in the analysis, to measure the corresponding effects on the quality characteristics, use the percentage distributions of each control parameter [27]. table 9, present the mechanical properties and density results using anova analysis. from these results it can be found that the significant parameter is the type of fiber, followed by filler and then the fiber volume fraction. the type of fiber contributions to mechanical properties and density are exceed 70% and 80% respectively. aa-modulus of elasticity b-tensile strength c-toughness d-density farag m. mohammed al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 7483(2017) 80 table 9, anova results of mechanical properties and density. parameters sum of squares (ss) degree of freedom (df) mean squares (ms) f value contribution (%) modulus of elasticity type of fiber 251.6187 2 125.8094 54.7421 78.76 filler 41.5502 2 20.7751 9.0397 13.01 fiber volume fraction 21.6940 2 10.8470 4.7197 6.79 error 4.5964 2 2.2982 1.44 total 319.4594 8 100.00 tensile strength type of fiber 109.8185 2 54.9092 78.1765 76.09 filler 32.9210 2 16.4605 23.4355 22.81 fiber volume fraction 0.1796 2 0.0898 0.1279 0.12 error 1.4048 2 0.7024 0.97 total 144.3238 8 100.00 toughness type of fiber 26.260 2 13.130 104.590 72.05 filler 9.8244 2 4.9122 39.1281 26.95 fiber volume fraction 0.1137 2 0.0568 0.4528 0.31 error 0.2511 2 0.1255 0.69 total 36.4501 8 100.00 density type of fiber 2.5516 2 1.2758 692.407 87.04 filler 0.2429 2 0.1215 65.9229 8.29 fiber volume fraction 0.1333 2 0.0667 36.1732 4.55 error 0.0037 2 0.0018 0.13 total 2.9315 8 100.00 5. confirmation test the optimum combinations parameters of processes with their levels were found using taguchi technique. but the optimum combinations did not match any experiment from experiments in orthogonal array. therefore, it is necessary to confirm results of taguchi technique with experimental results for the optimum combinations. the mechanical properties and density values at the optimum condition were predicted through use the optimum process parameters level [28]. the optimum combination parameters of mechanical properties are (a2b3c3), in which equivalent to (carbon fiber, 7.5%g filler and 33% fiber volume fraction). whereas the optimum combination parameters of density are (a2b1c1), that represent (carbon fiber, 0% filler and 27% fiber volume fraction). the s/n ratio of optimum combination process parameters can be predicted using the following equation [21]: '()* = '+ + � '� − '+" ��� … 4" where: '()*: predicted s n⁄ ratio. '+: total mean of s n⁄ ratios. '� :mean s n⁄ ratio at optimum levels. <: number of main design parameters that affact the quality characteristics. the predicted results were listed in table 10. tensile and charpy impact test specimens then prepared for the optimum combination parameters, and experiments of (tensile test and charpy impact test) had been done for mechanical properties, while its density was estimated. the results are shown in table 10. the results show that, the experimental and the predicted results are farag m. mohammed al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 7483(2017) 81 very close, with error not exceed 7.5%. this verify that the experiment result is correlated with the predicted result. from experiments and taguchi technique analysis, turns out the optimum combination parameters. without refer to the cost, but the cost is one of the most important factors that influence the selection of materials in engineering applications. the cost of unsaturated polyesters is approximately the same for all samples, as well as the cost of additives are very few in comparison with the fiber cost. therefore, it will be a focus on fiber as an effective parameter in the selection. it is necessary to optimize between the cost, weight (density) and mechanical properties. the combination parameters (carbon fiber, 7.5%g filler and 33% fiber volume fraction), gives higher mechanical properties with a very agreement density of (1478 kg/m 3 ), but higher cost, because the cost of carbon fiber is approach to 20th times the cost of e-glass fiber. the results of using finite element method showed that, the maximum stress on the wing is 40 mpa. so, from table 7, and the optimum combinations parameters, it can be choosing the combination parameters in which get the required selection. experiment number 9, present agreement combination parameters for the composite plate selection. this combination provides good mechanical properties, high safety factor, acceptable cost, and offers weight savings on average by 40% percent as compared to aluminum alloy. the parameters combinations of this experiment are ((eg+uc) fiber, 7.5% g filler and 30% fiber volume fraction). table 10, confirmation results characteristic optimum parameter level experiment predication difference (%) modulus of elasticity (gpa) a2b3c3 32.644 34.282 4.7 tensile strength (mpa) a2b3c3 548.627 542.426 1.1 toughness (mpa) a2b3c3 32.9507 35.646 7.5 density (kg/m 3 ) a2b1c1 1408.94 1400.700 0.57 6. conclusions from the results obtained in this work the following can be concluded: 1. the type of fiber is the significant parameter effect on the composite plate selection, followed by filler and finally the fiber volume fraction parameter. 2. the type of fiber parameter contributions on mechanical properties exceed 70%, while on density it is exceed 80%. 3. the optimum combination parameters with their levels of mechanical properties are (carbon fiber, 7.5 graphite filler, and 33% fiber volume fraction). whereas, the optimum combination parameters of weight are (carbon fiber, 0% filler, and 27% fiber volume fraction) 4. the agreement combination parameters with their levels are ((eg+uc) fiber, 7.5% graphite filler and 30% fiber volume fraction). this combination provides good mechanical properties, high safety factor, acceptable cost, and offers weight savings on average by 40% percent as compared to aluminum alloy. 7. references [1] torenbeek, e., “synthesis of subsonic airplane design”, delft university press, the netherlands, 1982. 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[22] astm designation: d 638-03, “standard test method for tensile properties of plastics”, astm international. [23] iso 179-1982 (e),” plastics-determination of charpy impact strength of rigid material”, international standard. [24] jr. anderson,” fundamentals of aerodynamics”, third edition, mcgraw hill, new york, 2001. [25] astm, "standard test method for tensile properties of fiber-resin composites/d3039", 1988. [26] roy, r.k. ,”a primer on the taguchi method”, competitive manufacturing series, van nostrand reinhold, new york, 1990. [27] sandhyarani biswas, amar patnaik and pradeep kumar, ”silicon carbide filled polymer composite for erosive environment application: a comparative analysis of experimental and fe simulation resultsc, silicon carbide-materials, processing and application in electronics devices, 2011. [28] g. bhanu kiran1, suman k. n. s., mohan rao n., uma maheswara rao r., ”a study on the influence of hot press forming process parameters on mechanical properties of green composites using taguchi experimental design”, international journal of engineering, science and technology, vol. 3, no. 4, pp. 253-263, 2011. ج ��� ���� ���� ��� 1، ا ��د�13��� ا ��ارز�� ا ������ ا� ،83-74 )2017( 83 ��� �� � ���اد ا ��!�"#!�� ��ا�� ��&���%���� ا ��اص ا ��'% ج ��� ���� ا*6%&5! ا*4#.3*23"! /01/ ا*(.-,! ا*#()و&"#%$"#"! drfaragmahel@yahoo.com -7(8*ا:*#4)و$9 ا: ��(� ا ص 3اا*lا4w<-ت . 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engineering journal al-khwarizmi engineering journal, vol. 15, no. 4, december, (2019) p. p. 5563 effect of pre-tension and orientation on the springback behavior of the sheet brass 65-35 aseel hamad abed* anwar hassan zabon** *,** department of production engineering and metallurgy engineering/ university of technology *email: aseelmo1972@gmail.com **email: anwar2238@gmail.com (received 15 april 2019; accepted 9 september 2019) https://doi.org/10.22153/kej.2019.09.005 abstract one of the most important phenomenon that occurs in sheet metal forming processes is the spring-back, which causes several geometrical alterations in the parts. the accurate prediction of springback after bending unloading is the key to the tool design, operation control, and precision estimate concerning the part geometry. this study investigated experimentally the effect of pretension in three rolling direction (0, 90, 45 degree) on the springback behavior of the yellow brass, sheet under v shape bending die. the pre-tension ranges from five different levels starting of 11% to 55% from the total strain in each rolling direction by regular increase of 11 %, then bent on a v-die 90 degree for the springback estimate. from experiment the results revealat that the springback increment with increase pretension ratio and the springback in 45° rolling direction is considerable than the sbringback in 90° rolling direction and the springback in 90° is greater than the sbringback in 0° rolling direction. keywords: pretension, orientation, springback, brass 65-35. 1. introduction sheet-metal forming processes (smfp) can be divided into two groups: cutting processes and plastic deformation processes. the advantage of the sheet metal parts that the material has a high yield strength (yσ) and a high elastic modulus (e), so that the parts created can be tough to have a good strength-to-weight ratio. a large number of techniques used to make sheet metal parts. one of the most widely applied metals forming operation is bending. by this technology, materials can be processed with various cross sections (sheet metal, bars, rods, pipes, wires. however, bending of sheet metal) most frequently used in industrial practice. first of all is in the car and ship building industry, there are different types of metal bending operations, one of the uttermost significant sheet metal bending operations is the (v–die) bending [1]. statement of the closing shape of the part after unloading (loading taken away) is a actual problem in manufacturing operation, in further, is necessary to design suitable tooling so as to lessen the effect of elastic recovery or springback (sb) in sheet bending which is a widespread phenomenon in (smfp), which leads to some geometrical changes in the parts [2]. after completing the bending process of the punch, the material attempts to return to its original state due to the elastic stresses occurring in the deformation zone of sheet metal but it cannot return due to the permanent plastic deformation. therefore, the sheet metal opens backwards slightly and reveals the spring back [3]. brass an alloy mainly include zinc (zn) and copper (cu), is wide used in diverse manufacturing due of their superior formability, strength to weight ratio, as well elevated corrosion resistance, and ductility. auto manufacturing is without fail in need of swift and strong automotive piece consequence it is feasible to production various parts and manufactured for aseel hamad abed al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 5563 (2019) 56 automobile implementation using the brass alloy [4]. in the past years, oversize of numerical and theoretical studies to foretell the (sb) characteristics of sheet metal had been carried out. investigated experimental and numerical the effect of dwell time on springback value of sheet material in v shape bending with different rolling direction and holding time in work pieces material [5]. springback reduces with increase in yield stress (yσ), compression depth, strain hardening (n), young’s modulus (e) and increasing thickness or decreasing the bending angle and the binders can be used to reduce springback effect and also helps to distribute the stress evenly [6]. investigated a die angle optimization method for reduce of (sb) in sheet metal bending operation in a (v-bending) die [7]. studied the effect of orientation and widths of the bending parallel, to the rolling direction on the slab. then extended the variation quasi-static parameter with different punch velocities in two steel materials [8]. presented the evaluated springback effect under various thicknesses and angles and using finite element method (fem) for (sb) statement of arbitrary form [9]. studied the effect of three parameters (punch angle, die opening and sheet width) on springback in sheet metal v-bending of steel sheet and determine the contribution of each process parameters towards springback effect [10]. introduced the cold-forming process using explicit dynamic (fem) and discussed the effect of thickness and curvature on springback of hull sheets was [11]. performed study and compare the spring back effect of two materials (ams 5504 & aluminum alloy) also investigated the causes for spring back effect and its remedial factors. so using finite element method in ansys software to approximation process is carried out [12]. it should be note that the previous research above studies the effect of many parameters on sbringback. the objective of present work is to know the behavior of the phenomenon of sbringback in case the sample used is predetermined in the pre-tension process in three rolling direction and their influence in the definitive shape of the product is positive or negative. 2. experimental equipments 2.1. materials the yellow brass sheet material was used in this work. it is called brass 65-35 (c26800) according to (asm) american society of metallic, it has excellent cold workability and widespread usage in the industry [13]. with sheet thickness (0.7) mm, to know the material characterization of it must be testing chemical composition, in table (1) listed the results of the chemical composition carried out at the specialized institute for engineering industries in iraq, with the asm caracterization. table 1, chemical composition and the asm for brass 6535. elements exp. asm zn% 35.23 35 pb% 0.007 0 mn% 0.00 0 sn% 0.001 0 p% 0.007 0 si% 0.001 0 fe% 0.021 0 ni% 0.001 0 al% 0.002 0 cu% 64.7 65 2.2. material properties to determine the mechanical properties of the sheet must be performing to tensile test. the specimens were first cut from the sheet and then made according to astm (american society for testing of materials) standard e-8m specification [14], as shown in fig. 1. fig. 1. dimensions of tensile specimen. as shown in fig. 2. the specimens were fixed carefully by the gripper, on universal testing machine wdw-200e, model (200e) electroaseel hamad abed al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 5563 (2019) 57 mechanical load frame with mechanical grips having maximum test force (200 kn) with accuracy of testing ±1% of indicated value, the relative error of displacement is ±5 %, and the speed range of cross beam is 0.1 mm/min ~ 500 mm/min, valid testing space 600 mm. this test was done in strength of materials laboratory in department of production engineering and metallurgy /university of technology. strength of materials laboratory, under cross head speed 5 mm/min, the specimen it loaded until fracture occurred. nine tensile specimens were tested in three directions (0°, 45°, 90°) by three samples in each direction in order to take the average values to reduce the errors obtained from the measurements, as shown in fig. 3. fig. 2. universal testing machine wdw model 200e electromechanical load frame with mechanical grips. fig. 3. tensile specimens (a) before test (b) after test the mechanical properties of it in three directions rolling (0 ̊), diagonal (45 ̊) and transvers (90 ̊). taguchi methods for designing experiments the mechanical properties of yellow brass as (asm) illustrated in table 2. while the relation between the true stress and true strain of brass sheet in three different directions is depicted in fig. 4. fig. 4. true stress-strain curves of brass 65-35 sheet in three different directions. table 2, mechanical properties of in three directions. property yield strength (mpa) ultimate tensile strength (mpa) %elogation to failure buisson,s ratio rolling (0o) 89 293 61 0.353 diagonal(45o) 52 245 64 0.243 transvers(90o) 64 270 55 0.239 asm 97 317 65 0.355 aseel hamad abed al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 5563 (2019) 58 2.3. dies used this study examined v-die bending tool, which designed and manufactured according to the standard specifications and consisted of two sections (punch and general die) both of them formed from (ck45). the first one is the general die, which is called lower die of opened type 90° angle in bottom bending. it has a rectangular shape of (99 × 108) mm and the height (48) mm with bending depth about (19) mm and opening die (40) mm. the second one is the upper die, which called the punch having 90° angle, as shown in fig. 5. the fixed velocity of the upper die is about (25) mm/min. fig. 5. the shape and dimension of die and punch. 2.4. springback test samples evaluation of the springback amount by implementing a sequence of experiments was the base of this work. in order to perform the experimental work, the testes must be a rectangular platelet (50 x 100) mm, according to template user as shown in fig. 6. 2.5. pre-tension the specimen was prepared following the rolling direction. considering the maximum strain of 0.12 (where the local necking happens after this point) under the uniaxial tensile loading path, five pre-tension states are used of 11%, 22% , 33% , 44% , and 55% , from the total strain in each rolling direction with a steady increase of 11% were selected to assign on the samples. the punching performed at a constant deformation rate of (5 mm/min) and then unloaded at the same deformation rate, as shown in fig. 7. fig. 6. dimension of specimen's springback. fig. 7. five different pre-tension levels used in three directions. aseel hamad abed al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 5563 (2019) 59 2.6. experimental bending devices agene universal testing machine model wdw-200e was used in the experimental work for the specimens in bending which was standard with wedge-shaped stretching attached, compression and bending, with the user and other attached to the form, as shown in fig. 8. the bending tests worked at a (25 mm/min) deformation speed, before that, the die and punch. in were loaded, the beginning, nine specimens without tension were bending at rate of three samples for each direction to tack the average values of them in order to reduce the errors obtained from the measurements. then, bending 45 sample that were pre-tensioned with five different levels of three directions at a rate of 15 sample for each direction (0, 45, 90) degree in the same old groove, where the sample without tension were bent as shown in fig. 9. fig. 8. bending device. fig. 9. bending the sample in three rolling direction. 2.7. springback measured the springback angle is the difference between sheet angle αf which formed after raising the load where the part tends to recover elastically after bending and its bend radius becomes larger when the tools are taken away the outer radius of the workpiece and punch angle αi or which called loading bending angle when punch / dies configuration in closed position, as shown in fig. 10. δα = αf ˗ αi …(1) will the springback factor is defined by the ratio of the final bending angle and to the loading bending angle, in case k = 1, it is refers to no spring back (αi = αf) but if k = 0 it refers to that complete elastic recovery of the bent material takes place (αf = 0). k= α f / α i …(2) by a mitutoyo 187-907 tool universal bevel protractor with a magnifying glass was used for the precise reading of angles on workpiece features or setting angle on machine tools hardened stainless steel construction that has blade length 150 mm. a high precision angle gauge was used for the accurate angle measurement of all angles, as shown in fig. 11. fig. 10. illustrate the difference between the final bending angle αf and loading bending angle αi. fig. 11 – a. the measuring device mitutoyo 187-907. (b) the device while measuring the angle of the sample. 3. results and discussions mensuration of springback can be defined as a difference between the angle after loading and after unloading. the measured values of springback and the calculated values of springback factor (ks) and values of pre-tension were measured for each specimen for the two directions as shown in table (3). the results show that the higher percentage of pre-tension has leaded to increase the change in length (∆l) and aseel hamad abed al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 5563 (2019) 60 greater the springback factor so thus increasing the springback there were situations whereby the final bending angle becomes bigger. fig. 12 show comparison between springback calculated with different direction to the rolling at different pre-tension. where it is clear that the pre-tension is a positive relationship to the springbacks and spring backs factor, i.e. the springback increases with the increase in pre-tension. as well the springback is higher in 45 degree to the rolling direction than in 90 degree to the rolling direction, and the springback is higher in 90 degree to the rolling direction than in parallel rolling direction. the main reason to the springback due to increase of dislocation density, which lead to the variation of mechanical behavior. strain is as well play big role in springback result, where the increasing in number of strain hardening will raise the value of springback due to bauchignerʼs influence, which authorize the material to follow dissimilar route through (loading – unloading) cycles. each of forming operation will happen in the plastic zone. wherefore to estimate or to analyses springback, nonlinear material attribute whose will adjust (stress strain) relationship in the nonlinear region are indispensable [15]. fig. 12. variation of the measured spring back with pre-tension in three directions. the pre-tension process has resulted in an increase in sample length from its original length (δl) as shown for each sample in table 3. fig. 13 show the relation between the change in length and spring back in parallel to rolling direction (0º), (45º) degrees to the rolling direction and (90°) respectively. where, it is clear that the change in length has a positive relationship to the springback i.e. the springback increases with increasing change in length. this leads to decrease the thickness, and the thickness has an inverse relationship with springback. fig. 13. relation between the change in length and spring back in three rolling direction. fig. 14 show comparison between springback degrees calculated with different direction to the rolling at different change in length, which shows that the springback is higher in 45 degree to the rolling direction than in (90°, 0°) to rolling direction respectively. the sheet metal is defined as having planar anisotropy when that give various flow strengths in various directions in the plane of the plate so the yellow brass is anisotropy, perpendicular, diagonal and parallel to the rolling direction assimilate the three vectors of the planar anisotropy. i.e. has different properties (yield strength, ultimate tensile strength and total tensile elongation) in different direction and that it has a great effect on the material properties this corresponds to the source no. [7]. where proved that “the springback decreases with increase in yield stress, strain hardening but it decreases with increase in young’s modulus and increasing thickness”. 0 5 10 15 20 25 30 35 0% 11% 22% 33% 44% 55% 66% sp ri n gb ac k an gl es in d eg re e pre-tension % transver on rolling dirction on rolling dirction diagonal on the rolling dirction aseel hamad abed al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 5563 (2019) 61 table 3, experimental measurements of springback and springback factor. fig. 14. comparison between relations measured springback with change in length on three rolling directions. 4. conclusions the present work has reached the following conclusions: 1. the pre-tension has a greater effect on the springback and springback factor, whereas the springback and springback ratio increase with the increase of pretension ratio so it has no positive effect on the springback compensation, and the pre-tension plays a remarkable role in the final sample geometry of the part. 2. the change in length is positive relationship to the spring back whereas the springback increase with the of increase change in length. 3. the orientation has a significant impact on the springback and springback factor. when the direction to the rolling angle is (45º), the spring back angle and spring back factor are higher than the (90º) for the direction to the rolling, while the lower spring back angle and lower springback factor resulted when the direction angle to the rolling is (0º). 5. references [1] a. ivaniševic, m. milutinovi, b. štrbac, and p. skakun, “stress state and spring back in vbending,” j. technol. plast., vol. 39, no. 2, pp. 158–168, 2013. [2] d. k. leu, “a simplified approach for distinguishing between spring-back and springgo in free u-die bending process of spfc 440 sheets,” mater. des., vol. 94, pp. 314–321, 2016. [3] [m. özdemi̇r, “mathematical modeling of the effect of different parameters on spring back in sheet metal formability process american journal of engineering research (ajer),” no. 10, pp. 198–205, 2017. springback factor springback pretention workpiece direction angle change in length (∆l) in mm percentage of total pre-tension 1.088 8 ̊ 0 0 % 1 0° 1.122 11 ̊3.11 11 % 2 1.144 13 ̊6.2 22 % 3 1.166 15 ̊9.3 33 % 4 1.188 17 ̊12.4 44 % 5 1.211 19 ̊15.5 55 % 6 1.188 17 ̊0 0 % 1 45° 1.211 19 ̊3.5 11 % 2 1.244 22 ̊7.05 22 % 3 1.277 25 ̊10.55 33 % 4 1.311 28 ̊14.1 44 % 5 1.344 31 ̊17.65 55 % 6 1.44 13 ̊0 0 % 1 90° 1.17 15 ̊2.95 11 % 2 1.2 18 ̊5.95 22 % 3 1.23 21 ̊8.93 33 % 4 1.27 24 ̊11.9 44 % 5 1.3 27 ̊14.85 55 % 6 aseel hamad abed al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 5563 (2019) 62 [4] s. k. panthi, n. ramakrishnan, m. ahmed, s. s. singh, and m. d. goel, “finite element analysis of sheet metal bending process to predict the springback,” mater. des., vol. 31, no. 2, pp. 657–662, 2010. 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[10] r. d. gedekar, s. r. kulkarni, and m. b. kavad, “optimization of input process parameters affecting on springback effect in sheet metal ‘v’ bending process for cr2 grade steel sheet of is 513-2008 material by using taguchi method,” int. res. j. eng. technol., no. july, p. 381, 2008. [11] “comparative study on spring back effect of sheet,” vol. 14, pp. 1871–1890. [12] z. yue, j. qi, x. zhao, h. badreddine, j. gao, and x. chu, “springback prediction of aluminum alloy sheet under changing loading paths with consideration of the influence of kinematic hardening and ductile damage,” metals (basel)., vol. 8, no. 11, p. 950, 2018. [13] v. drossou-agakidou et al., administration of recombinant human granulocytecolony stimulating factor to septic neonates induces neutrophilia and enhances the neutrophil respiratory burst and β2 integrin expression results of a randomized controlled trial, vol. 157, no. 7. 1998. [14] w. materials, r. head, and w. screws, “notice: this standard has either been superseded and replaced by a new version or discontinued. contact astm international (www.astm.org) for the latest information. standard test methods for mechanical fasteners in wood 1 notice: this standard has e,” vol. 88, no. march, 1989. [15] s. a. kagzi, a. h. gandhi, h. k. dave, and h. k. raval, “an analytical model for bending and springback of bimetallic sheets,” mech. adv. mater. struct., vol. 23, no. 1, pp. 80–88, 2016. )2019( 5563، صفحة ٤د، العد15دجلة الخوارزمي الهندسية المجلماسيل حمد عبد 63 رالرجوعية في صفيحة النحاس االصفاهرة ظتأثير الشد المسبق واتجاهية المعدن على سلوك **انوار حسن زبون *اسيل حمد عبد ةالتكنولوجي ةالجامع /م هندسة االنتاج والمعادنقس،*** aseelmo1972@gmail.com : البريد االلكتروني* anwar2238@gmail.com : البريد االلكتروني** ةالخالص في االجزاء. ان التنبؤ الدقيق احد اهم الظواهر التي تحدث في عمليات تشكيل الصفائح المعدنية والتي تسبب عدة تغييرات هندسية ظاهرة الرجوعية تعد هذه الدراسة تحرت للرجوعية بعد رفع الحمل بعملية الحني هي المفتاح لعدة التصميم والسيطره على العمليات والتخمين الدقيق فيما يتعلق بهندسة االجزاء وك ظاهرة الرجوعية في صفيحة النحاس االصفر بعملية ) درجة على اتجاه الدرفلة على سل٠٬٤٥٬٩٠اتجاهات ( ةبثالثبشكل تجريبي تأثير الشد المسبق %١١قابلية الشد الكلي لكل اتجاه بزيادة منتظمة مقدارها من %٥٥الى %١١مستويات مختلفة تبدأ من ة، تم الشد المسبق بخمس v الحني قي قالب شكل هرت النتائج العملية ان الرجوعية تزداد بزيادة نسبة الشد وان ظادرجة لغرض تخمين الرجوعية ، ٩٠زاوية vومن ثم تم حني العينات في قالب شكل درجة اكبر من الرجوعية باالتجاه ٩٠درجة وان الرجوعية باالتجاه ٩٠درجة على اتجاه الدرفلة اكبر بكثير من الرجوعية باالتجاه ٤٥الرجوعية باالتجاه صفر على اتجاه الدرفلة. correlation for fitting multicomponent vapor-liquid equilibria data and prediction of azeotropic behavior al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 4, no. 4, pp 9-25 (2008) extraction of phenol from industrial water using different solvents mahmoud omar abdullah*, khalid farhod al-jiboury** and bushra yaseen*** *chemical engineering department/ al-nahrain university **chemical engineering department/ university of technology ***chemical engineering department/ al-mustanserya university (received 7 october 2007; accepted 11 septerber 2008) abstract the analysis and efficiency of phenol extraction from the industrial water using different solvents, were investigated. to our knowledge, the experimental information available in the literature for liquid-liquid equilibria of ternary mixtures containing the pair phenol-water is limited. therefore the purpose of the present investigation is to generate the data for the water-phenol with different solvents to aid the correlation of liquid-liquid equilibria, including phase diagrams, distribution coefficients of phenol, tie-lines data and selectivity of the solvents for the aqueous phenol system. the ternary equilibrium diagrams and tie-lines data for systems containing water-phenol-benzene, water-phenolchloroform, water-phenol-iso-butyl acetate, water-phenol-butanol, water-phenol-ethyl methyl keton and waterphenol-toluene, were determined at 303 k and atmospheric pressure. the capacity and selectivity of these organic solvents in each of these systems were determined from the tie-lines data. the capacity of the isobutyle acetate was found to be the highest among the other solvents, and its selectivity was also the highest. similar results also were obtained for the ethyl methyl keton but gave less capacity and selectivity as compared to the isobutyle acetate. it can be concluded that both isobutyle acetate and ethyl methyl keton are good solvents for extraction of phenol from industrial water. the liquid-liquid equilibrium data of ternary systems were correlated to the nrtl, uniquac and unifac models of activity coefficient to determine their adjustable parameters. the standard deviations from experimental compositions were calculated. results show that the correlation may be greatly improved by applying the nrtl model with the regression criteria based on minimizing the experimental and calculating distribution coefficients sk to give an average value of the root mean square deviation about 1.436 % and in terms of the average errors in the distribution ratio for all tie-lines about 10.776 %. keywords: liquid -liquid equilibria, extraction of phenol, activity coefficient. 1. introduction: phenol is an example of a highly toxic chemical substance. the maximum amount sanctioned by the world health organization in drinking water is 0.001 mg/l., macedo and soares (1996). this component is found in large quantities in the effluents of different petrochemical factories and is regularly released into the rivers. therefore there is great need for elimination phenol from the water, on the other hand, phenol constitutes a valuable component in the production of various chemicals and could be reclaimed from the water to great advantage. the separation process most widely used in the industry is the extraction with solvents. to design new equipment or to simulate the performance of existing units, it is important to have access to liquid-liquid equilibrium data. solvent extraction is a major unit operation based entirely on limited liquid miscibility and the distribution of solute between two liquid phases. in the design of a separation process and indeed whenever solvents are used in chemical technology it is unconditionally necessary to know from data or from calculation, the composition of the two phases in equilibrium. mahmoud omar abdullah al-khwarizmi engineering journal, vol.4, no.4, pp 9-25 (2008) 10 for many types of mixture containing for example strongly polar molecules, it is necessary to use activity coefficient and hence expression for the excess gibbs function g e for the calculation of liquid phase fugasities, hull and kronberg (2006). the aim of this research is to obtain the necessary liquid-liquid equilibrium data for the extraction of phenol from water. phase equilibrium data of the ternary systems waterphenol-organic compounds were generated including phase equilibrium diagrams, distribution coefficients of phenol, tie-lines data and selectivity of the solvent. tie-lines of two phase conjugate layers were determined by use of crosssection method and the accuracy of experimental tie-line data for the ternary was checked for six different solvents. the nrtl, uniquac and unifac models were used to correlate the experimental data obtained for the ternary systems under study. the results showed whether the above model is fitted or not to the systems under consideration. a computerized procedure for predicting or representing multicomponent liquid-liquid phase equilibrium was developed by using the combination of optimization theory and thermodynamic. the systems studied in this investigation were water-phenol-benzene, water-phenolchloroform, water-phenol-isobutyle acetate, water-phenol-butanol, water-phenol-butanone and water-phenol-toluene. 2. experimental work chemicals: the chemicals used was supplied from local markets. the selection of the six solvents is based on the available solvents in the local market which is considered to be controlling factor in this study. in spite of that the solubility parameters of the six selected solvents is within the range of 10.4 – 8.9. these chemicals were presented in table 1 with their purities. physical properties such as density of these materials used in this study were measured experimentally by measure the refractive index and compared with values in the literature (frances, 1963; fredenslund and rasmussen, 1985; jone and theodore, 1986). 3. refractive index measurement: the refractive index was determined by a refractometer of the specification abbe, the precision of the refractive indices was 0.0002 units. refractive indices for the samples of liquid were measured and the values presented were the average values of at least three independent readings for each sample. the samples were thermostated by circulating water from a constant temperature bath through the refractometer. the constant temperature at which the measurements were taken was 30 o c and atmospheric pressure. 4. experimental apparatus: the experimental work was carried out using erlenmeyer flask with a stopper to prevent evaporation with a capillary inserted into the stopper, whilst maintaining a constant agitation by means of a magnetic stirrer. the flask has jacket through which water from a haake thermostat bath was circulated. temperature was measured by means of a precision thermometer, with an accuracy of ± 0.1 o c. the apparatus shown diagrammatically in figure 1. fig.1. cloud point titrator for liquid-liquid equilibria. mahmoud omar abdullah al-khwarizmi engineering journal, vol.4, no.4, pp 9-25 (2008) 11 5. experimental procedure: the procedure involves operating the apparatus at steady state in order to predict the properties of liquid-liquid equilibria for ternary systems. 6. determination of the binodal curves; the binodal curves of the ternary systems were determined by the method of titration as described by (alders, 1959). the solvent 3 was added to the mixture of water 1 and phenol 2 in the sample bottle inside the constant temperature water-jacket. as soon as the cloud point was reached, phenol 2 was then added to make the liquid homogenous again. the procedure was repeated a number of times, and the successive cloud points were connected up to produce the binodal curve. the maximum error of binodal points determination was ± 0.2 %. table 1 physical properties of chemicals used at 303 k. component m. wt. density refractive index boiling point o c purity % supplier exp. lit. exp. lit. benzene 78.114 0.8683 0.8685 1.496 1.4962 80.1 99 % bdh butanol 74.12 0.8053 0.8057 1.3970 1.3971 117.7 99.5 % bdh butanone 72.11 0.7941 0.7941 1.3770 1.3773 79.6 99.5 % bdh chloroform 119.38 1.4693 1.4706 1.4400 1.4401 61.2 99 % bdh iso-butyl acetate 116.16 0.8621 0.8599 1.3880 1.3880 117.5 99 % bdh toluene 92.14 0.8575 0.8577 1.4930 1.4935 110.6 99 % bdh water 18.015 0.9951 0.9956 1.3340 1.3342 100.0 99.5 % bdh phenol 94.113 1.588 1.587 1.5423 1.5395 181.8 99.5 % merck 7. determination of the tie lines: the determination was carried out using a double-walled similar to that described by (novak, 1987). the separating funnels containing heterogeneous mixture of three components were placed in a thermostat bath. temperature was controlled within an accuracy of ± 0.01 o c by using a temperature regulator as shown in fig.2. the prepared heterogeneous mixtures were shaken for at least 20 min., equilibration of the two phases took place in a thermostatted doublewalled separating funnels (250 ml) over a period of 20 hr. after equilibrium had been reached, the refractive index of one of the separated phases was measured. the composition of the tie-lines was calculated numerically from the calibration data by polynomial regression analysis. the third order polynomial was the best approximation (stand. dev. = 1.5*10-4) of the relation between refractive index and composition. fig.2. thermostatted separating funnel for determining tie-lines 1-separating funnel, 2-thermostatting mantle, 3-thermometer holder, 4-stop cock. mahmoud omar abdullah al-khwarizmi engineering journal, vol.4, no.4, pp 9-25 (2008) 12 to determine the tie-lines of the two conjugate layers, ternary two phase systems were analyzed by the so-called cross-section method reported by (radecki and grzyboski, 1975). this method consists of plotting the refractive index of a mixture against concentration of one of the components at a constant ratio of the remaining two components. 8. results and discussion tie-line data: the tie-line data between the two conjugate phases were obtained from the cross-section method. the liquid-liquid equilibrium data (tieline data) obtained experimentally for the series of the ternary systems water-phenol-benzene, waterphenol-chloroform, water-phenol-isobutyl acetate, water-phenol-butanol, water-phenol-butanone and water-phenol-toluene at 30 o c were plotted in figures 3 to 8, the data of (macedo and soreas, 1996) for the system water-phenol-benzene was plotted in figure 3 for comparison only. the tie-lines data were used to determine the selectivity (ki) and distribution coefficients (sij) for the systems under investigation according to the following relationships: )1..(. e phasen raffination of i iconcentrat phasen extract ion of i iconcentrat k i )2...( k k s j i ij the subscript (i) is referred to phenol component and (j) is referred to water component one. a simple graph of distribution curve for phenol compound between the two immiscible phases were obtained by plotting the concentration of phenol compound in organic phase against its concentration in the aqueous phase, and presented in figure 9. this type of diagram could be compared to a y-x plot for the presentation of vapor-liquid equilibrium data, and the deviation of each curve from the y-x line is a measure of the selectivity of solvent. as the deviation increases the selectivity of the solvent increases. fig. 3. experimental liquid-liquid equilibrium of ternary system water-phenol-benzene. fig. 4. experimental liquid-liquid equilibrium of ternary system water-phenolchloroform. fig. 5. experimental liquid-liquid equilibrium of ternary system water-phenol-isobutyl acetate. mahmoud omar abdullah al-khwarizmi engineering journal, vol.4, no.4, pp 9-25 (2008) 13 fig.6. experimental liquid-liquid equilibrium of ternary system water-phenol-butanol. fig.7. experimental liquid-liquid equilibrium of ternary system water-phenol-butanone. fig.8. experimental liquid-liquid equilibrium of ternary system water-phenol-toluene. fig.9. distribution coefficient of phenol between water layer and solvent layer at 303 k. fig.10. othmer-tobias correlation for waterphenol-solvent at 303 k. 9. evaluation of the consistency of the experimental tie-lines: the accuracy of the experimental data for the six ternary systems at 30 o c was checked by plotting in figures 10 and 11, the othmer-tobias correlation (othmer and tobias, 1942): )3...( 1log 1log  n x -x m x -x ss ss ww ww mahmoud omar abdullah al-khwarizmi engineering journal, vol.4, no.4, pp 9-25 (2008) 14 figures 10 and 11 can be useful to check whether experimental data have a regular or not. this can help to identify some tie-lines with high random errors. fig. 11. othmer-tobias correlation for waterphenol-solvent at 303 k. figures 3 to 8 show the equilibrium diagrams of the systems water-phenol-organic solvent (benzene, chloroform, isobutyle acetate, butanol, butanone (mek) and toluene). the six solvents are totally miscible with phenol. for butanol system the two phase area is small. a small area has the disadvantage that the purity of the extract is low and that, more over, only mixtures of limited concentrations can be extracted (alders, 1959). thus it follows for figure 6 that with butanol as extractive solvent at 303 k, no mixtures can be separated that contain more than 40 % of phenol. for benzene the area under the binodal curve is large and for figure 3 it can be seen that mixtures of 70 % phenol can be extracted with benzene. in figures 4, 5, 7 and 8 the same conclusions can be reached for the other solvents. figure 9 verifies this result. it shows the distribution curves of benzene, chloroform, isobutyle acetate, butanol, butanone and toluene. the distribution coefficient of phenol was higher towards isobutyle acetate and butanone than for the other solvents. also, the liquid-liquid equilibrium data presented were plotted in figure 10 in the form of separation factor (s) versus the equilibrium distribution ratio of phenol (k), in the range of concentration under observation. this study showed that, for all the solvents considered, the organic ester and keton emerge as the most indicated for the separation of phenol from water. although isobutyle acetate and mek have similar distribution curve. the boiling point and specific gravity of mek differ greatly from those of phenol, and so mek is a more suitable solvent for phenol. fig.12. separation factor versus equilibrium distribution ratio for extraction of phenol from water with solvents at 303 k. 10. correlation methods estimation of parameters: the nrtl equation (renon and prausnitz, 1968), the uniquac equation (anderson and prausnitz, 1978) and the unifac equation (fredenslund and prausnitz, 1982) were used to correlate the experimental phase equilibrium data. binary parameters were calculated using the maximum likelihood procedure for the minimization of the following objective functions )4(... 2 1 1 ln-ln1                             k m k n i γ γ x xf ii i i i i i ii i   )5...( 1 1 2 1 2 -ˆ2      m k n i j ijkjk xxf i the calculation begins using the objective function f1 and when the parameters are near mahmoud omar abdullah al-khwarizmi engineering journal, vol.4, no.4, pp 9-25 (2008) 15 optimum value the calculation continues with the objective function f2. for ternary mixtures nine parameters for the nrtl equation must be fitted, six parameters for the uniquac equation and the predictive method for unifac equation for describing a ternary data set. this procedure gives a set of parameters shown in tables 2 and 3 11. calculation of tie-lines: the above mentioned procedure for estimated – parameters were employed to calculate the tielines. computation started from the heterogeneous mixture: )6...( 2   xx z ii i i i i the computation of tie-lines was based on the algorithm published by (null, 1970) figures 13, 14, 15, 16, 17 and 18 represent nrtl models correlation with two regression criteria for the systems under study. a good representation was obtained in figures 13, 15, 16, 17 and 18 for the two regression criteria sa, sk and the residuals to the experimental data were low but residuals to the distribution coefficients was better for the regression criteria sk than the regression criteria sa for all the systems. for chloroform system, the nrtl model represents the correlation with the regression criteria sk only and give a good residuals for both the experimental data and the distribution coefficients. figures 19, 20, 21, 22, 23 and 24 represent the uniquaq modeling to the ternary system under study. for all the systems the residuals were higher for the experimental data and the distribution coefficient, and representation was better for the nrtl model than the uniquac model. for all the systems above it can be seen that, at low concentration of the solute both the nrtl model and uniquac model fit the experimental data. but at high concentrations the deviation from experimental are obvious. figures 25, 26, 27, 28, 29 and 30 represent unifac models correlation for the systems under study. in figures 25, 26, 27, 28, 29 and 30 the residuals were higher for the experimental data, and representation was better for both the nrtl model and uniquac model than the unifac model. for butanol system, the unifac model gives good residuals for both the experimental data and the distribution coefficients than the uniquac model. table 2 nrtl correlation parameters for ternary system in kj/mol at 303 k. solvent i-j aij aji ij benzene 1-2 1-3 2-3 1267.83346 1595.76351 -265.14854 -125.07542 1108.3348 858.27337 0.21906 0.31233 0.42423 chloroform 1-2 1-3 2-3 1084.83814 2024.50135 116.82185 154.68756 473.8733 263.54813 0.5169 0.19131 0.60211 iso butyl acetate 1-2 1-3 2-3 1552.05204 1973.83952 2190.65119 136.07517 651.2274 20.7399 0.5743 0.28968 0.67227 butanol 1-2 1-3 2-3 1244.98256 2193.96024 782.10278 119.92193 501.96555 379.55085 0.53109 0.34753 0.69905 mek 1-2 1-3 2-3 1527.03582 3037.4255 2299.1531 -448.7063 148.9289 -2185.0569 0.16978 0.21666 0.06204 toluene 1-2 1-3 2-3 1370.2677 1376.6916 -476.4699 -208.4991 822.2341 1533.0258 0.2116 0.2566 0.2385 mahmoud omar abdullah al-khwarizmi engineering journal, vol.4, no.4, pp 9-25 (2008) 16 table 3 uniquac correlation parameters for ternary system in kj/mol at 303 k. solvent i-j bij bji benzene 1-2 1-3 2-3 -7.1734 220.908 -53.1383 164.64 514.0597 91.1305 chloroform 1-2 1-3 2-3 52.6238 643.2392 81.6293 345.7274 425.8234 78.7847 iso butyl acetate 1-2 1-3 2-3 267.108 158.795 2141.241 322.71 1106.435 -282.265 butanol 1-2 1-3 2-3 90.3247 2514.7869 827.905 80.0523 473.0648 -270.6094 mek 1-2 1-3 2-3 93.4385 949.4014 1543.2946 396.148 546.9067 423.9119 toluene 1-2 1-3 2-3 -103.013 47.108 -246.023 375.872 1139.4387 904.198 table 4 classical and statistical regression criteria.         m n ii ik ii ik i ik i ik k i γxγxs a 1 1 2 …(7) 2 1 1              m n ii ik i ik ii ik i ik k i aa aa s a …(8) 2 1 1 lnln kk i m n i i ii i i i ii i γ γ x x s k                                 …(9) fig. 13. representation of the ternary system water-phenol-benzene by nrtl model with parameters obtained from lle data at 303 k. mahmoud omar abdullah al-khwarizmi engineering journal, vol.4, no.4, pp 9-25 (2008) 17 fig.14. representation of the ternary system water-phenol-chloroform by nrtl model with parameters obtained from lle data at 303 k. fig.15. representation of the ternary system water-phenol-isobutyle acetate by nrtl model with parameters obtained from lle data at 303 k. fig.16. representation of the ternary system water-phenol-butanol by nrtl model with parameters obtained from lle data at 303 k. fig.17. representation of the ternary system water-phenol-mek by nrtl model with parameters obtained from lle data at 303 k. fig.18. representation of the ternary system water-phenol-toluene by nrtl model with parameters obtained from lle data at 303 k. fig.19. representation of the ternary system water-phenol-benzene by uniquac model with parameters obtained from lle data at 303 k. mahmoud omar abdullah al-khwarizmi engineering journal, vol.4, no.4, pp 9-25 (2008) 18 fig.20. representation of the ternary system water–phenol-chloroform by uniquac model with parameters obtained from lle data at 303k. fig.21. representation of the ternary system water-phenol-isobutyle acetate by uniquac model with parameters obtained from lle data at 303 k. fig.22. representation of the ternary system water-phenol-butanol by uniquac model with parameters obtained from lle data at 303 k. fig.23. representation of the ternary system water-phenol-mek by uniquac model with parameters obtained from lle data at 303 k. fig.24. representation of the ternary system water-phenol-toluene by uniquac model with parameters obtained from lle data at 303 k. fig.25. representation of the ternary system water-phenol-benzene by unifac model with parameters obtained from lle data at 303 k. mahmoud omar abdullah al-khwarizmi engineering journal, vol.4, no.4, pp 9-25 (2008) 19 fig.26. representation of the ternary system water-phenol-chloroform by unifac model with parameters obtained from lle data at 303 k. fig.27. representation of the ternary system water-phenol-isobutyle acetate by unifac model with parameters obtained from lle data at 303k. fig.28. representation of the ternary system water-phenol-butanol by unifac model with parameters obtained from lle data at 303 k. fig.29. representation of the ternary system water-phenol-mek by unifac model with parameters obtained from lle data at 303 k. fig.30. representation of the ternary system water-phenol-toluene by unifac model with parameters obtained from lle data at 303k. 12. correlation: in liquid extraction studies experimental results obtained for low solute concentrations are most important. table 5 shows the root mean square deviation between the experimental and calculated values for the tie-lines, as calculated from the formula )10...(min 2 1 1 1 1 2 6ˆ100                         k k n j i i mijk x ijk xfrmsd and the average error in the distribution ratio for all tie-lines mahmoud omar abdullah al-khwarizmi engineering journal, vol.4, no.4, pp 9-25 (2008) 20 )11...( 2 1 2 -ˆ100                         k kkk mββββ table 5 residuals for the six ternary liquid-liquid equilibrium data set correlated by nrtl, uniquac and unifac at 303 k. data set no. residuals nrtl uniquac unifac sa sk sa sa’ sk sk 1 f 0.342 1.4704 1.092 1.73 1.859 1.4996  117.98 15.284 96.84 17.38 16.165 19.318 2 f 0.432 0.7267 1.021 0.405 0.501 0.5649  65.76 12.645 97.787 15.359 15.757 19.106 3 f 0.543 1.788 0.7411 2.697 1.287 2.445  32.944 9.005 68.856 29.725 31.369 21.054 4 f 0.2496 0.9316 0.412 2.729 2.731 2.482  13.975 1.9572 152.02 5.608 5.608 8.803 5 f 1.122 1.867 1.058 2.475 2.058 2.703  73.989 4.75 51.828 14.146 19.201 14.948 6 f 1.234 1.832 1.949 2.308 1.93 2.843  129.28 1.54 172.92 6.173 9.895 46.86 average f 0.9775 1.436 1.045 2.057 1.727 2.089  73.634 1.13 106.71 14.732 16.332 21.685 an analysis of table 5, shows that for all data sets the binodal curves are well reproduced by the regression criteria sa for both models nrtl and uniquac model but give a high residuals of the phenol distribution ratios for almost all the system as indicated by the residual . the overall fit measured by f is worse when both sa’ and sk were applied to uniquac model but a large improvement in the values of  is obtained as compared with the results of the regression criteria sa. using the unifac equation, the correlation residuals does not improve the results. the nrtl models results using the regression criteria sk can be more accurate than the uniquac equation and give good improvement in f and the values of . table 5 verifies the results of the above figures. the disagreement between the experimental and calculated results, expressed in terms of solute distribution ratios, is more easily visualized in figures 31, 32, 33, 34, 35 and 36. figure 31, shows the experimental phenol distribution ratio at 30 o c together with those calculated by using the nrtl (sa and sk, which gave the best nrtl results), uniquac (sa, sa’ and sk) and unifac (sk). the nrtl results can be seen to be more accurate with the objective function sk than the other models with the different objective function. the results for the other five systems, figures 32, 33, 34, 35 and 36 are similar to that of figure 31. mahmoud omar abdullah al-khwarizmi engineering journal, vol.4, no.4, pp 9-25 (2008) 21 fig.31. experimental and calculated distribution ratio of water-phenolbenzene at 303 k. fig.32. experimental and calculated distribution ratio of water-phenol-chloroform at 303 k. fig.33. experimental and calculated distribution ratio of water-phenol-isobutyle acetate at 303k. fig.34. experimental and calculated distribution ratio of water-phenolbutanol at 303 k. mahmoud omar abdullah al-khwarizmi engineering journal, vol.4, no.4, pp 9-25 (2008) 22 fig.35. experimental and calculated distribution ratio of water-phenolmek at 303 k. fig.36. experimental and calculated distribution ratio of water-phenol-toluene at 303 k. table 6 fitting accuracy of ternary lle data no. nrtl uniquac unifac sa sk sa sa’ sk sk x x x x x x i ii i ii i ii i ii i ii i ii 1 15.1 16.9 18.8 1.66 13.8 16.3 23.8 2.01 4.8 7.20 28.4 1.98 2 0.76 0.76 9.76 0.64 11.8 6.51 5.28 0.83 22.1 1.25 7.52 0.98 3 6.51 1.06 22.1 0.47 8.93 12.1 35.3 1.01 17.1 1.53 32.6 1.27 4 3.15 0.62 11.7 0.39 3.49 4.28 36.8 0.76 36.8 0.78 32.7 0.48 5 5.55 14.2 24.2 2.11 13.2 5.33 48.3 1.38 27.3 0.72 38.1 2.12 6 7.13 0.56 22.0 0.41 9.63 13.2 33.2 1.54 29.1 1.79 25.6 2.16 av. 7.49 6.69 18.1 0.95 10.2 29.2 30.5 1.25 22.8 2.13 27.5 1.53 13. comparison of fitting accuracy: the fitting accuracy of six set of ternary lle data applying nrtl with two regression criteria, uniquac with three regression criteria and unifac with one regression criteria are listed in table 6, it can be seen from the table that correlation is improved by applying the nrtl model with regression criteria sk . 14. conclusions: 1. of the six solvents used to extract phenol from an aqueous phenol solution, both iso-butyle acetate and etyl methyl keton have the highest selectivity and capacity because the iso-butyle acetate hydrogen bonds and ethyl methyl keton hydrogen bond preferentially with phenol. and due to the greatest differences between the boiling point and specific gravity of the ethyl methyl keton and those of phenol. it is therefore considered an excellent mahmoud omar abdullah al-khwarizmi engineering journal, vol.4, no.4, pp 9-25 (2008) 23 solvent for extracting phenol from phenol-water solutions. 2. the consistency of experimental tie-line data for the ternary system water-phenolsolvent at 30 o c was confirmed for six different solvents, and the data can then be used to calculate the values of the parameters and the tie-lines in the nrtl, uniquac and unifac models. 3. the nrtl model for the activity coefficients of ternary liquid systems gives a good representation of liquidliquid equilibria for the systems under study. this fact helps for calculations required in the design of extraction unit to reach the optimum use of the solvent. 4. the root mean-square deviation f between the calculated and the experimental tie-lines lays within the range of 1.867-0.726 for the nrtl model for the objective function f2 and in terms of the error  the range is lays within 15.284-9.005. 5. the nrtl equation gives f values slightly lower than those of the uniquac equation but the difference is not significant it is 1.2-1.1 times larger than the nrtl model. 6. the nrtl equation gives the best  results, in which case it proves to be more accurate than the uniquac equation at all objective functions, it is 1.5 times larger than the nrtl model. 7. the unifac equation gives f values slightly lower than those of the uniquac equation for the system containing an alcohol component but the difference is not significant. 15. nomenclature abbreviations: lle liquid – liquid equilibrium mek methyl ethyl keton (butanone) nrtl non-random two liquid activity coefficient model rmsd root mean square deviation unifac uniquac functional group activity coefficients model uniquac universal quasi-chemical activity coefficient model 16. symbols: ai activity of component i f1 objective function no. 1 f2 objective function no. 2 g e excess gibbs function ki selectivity m slope of the line m no. of experimental points m.wt. molecular weight n intersect of the line sa classical regression criteria sk statistical regression criteria sij distribution coefficient x i i mole fraction of component i in the i phase x ii i mole fraction of component i in the ii phase xss mole fraction of solvent in the solvent phase xww mole fraction of water in the water phase zi number of mole of component i in the system 17. greek litters:  average error  activity coefficient 18. superscript: e excess property i phase i ii phase ii ^ experimental value i component i j component j ss solvent in the solvent phase ww water in the water phase mahmoud omar abdullah al-khwarizmi engineering journal, vol.4, no.4, pp 9-25 (2008) 24 19. references: [1] alders, l., “liquid-liquid extraction” 2nd ed., elsevier publishing co., 1959 [2] anderson, t. f. and prausnitz, j., m., ind. eng. process des. and dev., 17, 1978. [3] francis, a. w., “liquid-liquid equilibrium” interscience publishers, newyork, 1963. [4] fredenslund aa. and rasmussen p., “vaporliquid equilibria using unifac a group contribution method, elsevier, amsterdam, 1977 [5] fredenslund aa. and rasmussen p., fluid phase equilibria, 24, 115-150, 1985. [6] hull, a. and kronberg b., j. chem. eng. data, 51, 202-208, 2006 [7] john a. r., william b. and theodore k., “organic solvents”, 1986. [8] macedo e. a. and soares m. e.,fluid phase equilibria, 26, 36-42, 1996. [9] novak j. p., matous j. and pick j., “liquidliquid equilibria”, elsevier, amsterdam, 1987. [10] null h. r., phase equilibrium in process design, 1970. [11] othmer d. f., ind. eng. chem., 38, 11-19, 1942. [12] radecki a. and grzyboski j., j. chemical and engineering data, 20, 2, 1975. [13] renon h. and prausnitz m., aiche journal, 14, 1, 1968. (2008 )25-9، صفحة 4، العذد 4 هجلة الخىارسهي الهنذسية الوجلذ د عوزوهحن 25 استخالص الفينىل هن الوياه الصناعية باستخذام هذيبات هختلفة *** بشزي ياسين** خالذ فزهىد*هحوىد عوز جايعح انُهشٍَ / لسى انهُذسح انكًُُاوَح * انجايعح انركُىنىجُح / لسى انهُذسح انكًُُاوَح ** انجايعح انًسرُصشَح / لسى انهُذسح انكًُُاوَح *** الخالصة تحسة انًعهىياخ انعًهُح انًحذودج انًرىفشج فٍ . ذى ذحهُم و دساسح كفاءج اسرخالص انفُُىل يٍ انًُاِ انصُاعُح تاسرخذاو يزَثاخ يخرهفح سائم نألَظًح انثالثُح وانرٍ ذحىٌ عهً انثُائٍ انًاء و انفُُىل ،فاٌ انهذف يٍ هزِ انذساسح هى – انُششاخ وانًجالخ انعهًُح نرىاصٌ سائم انسائم ألَظًح انًاء و انفُُىل يع انًزَثاخ انًخرهفح تضًُها يخطظ – يعشفح تُاَاخ انرىاصٌ نألطىاس نغشض إَجاد عاللاخ ذىاصٌ انسائم . األطىاس ، يعايم انرىصَع نهفُُىل وتُاَاخ خطىط انرىاصٌ واَرمائُح افضم يزَة نهفُُىل اَضوتُىذاَم اسُرُد ، -فُُىل-كهىسوفىسو ، ياء-فُُىل-تُضٍَ ، ياء-فُُىل-ياء: ذى إَجاد تُاَاخ يخططاخ انرىاصٌ نألَظًح انثالثُح انرانُح . كهفٍ وضغظ جىٌ واحذ 303ذهىٍَ عُذ دسجح حشاسج -فُُىل-اثُم يثُم كُرىٌ و ياء-فُُىل-تُىذاَىل ، ياء-فُُىل-ياء نمذ وجذ اٌ سعح . ذى حساب سعح واَرمائُح كم يٍ هزِ انًزَثاخ انعضىَح نكم يٍ األَظًح انًزكىسج أعالِ يٍ تُاَاخ ذىاصٌ األطىاس كًا إٌ اَرمائُح انًزَة اعالِ هٍ األعهً ، تًُُا كاَد سعح و اَرمائُح يزَة . األَضوتُىذاَم اسُرُد هٍ األعهً يماسَح يع انًزَثاخ األخشي ًَكٍ انمىل اٌ كم يٍ يزَة األَضوتُىذاَم اسُرُد و يزَة . االثُم يثُم كُرىٌ الم يٍ انًزَة أعالِ واألعهً يماسَح يع انًزَثاخ األخشي . االثُم يثُم كُرىٌ يٍ انًزَثاخ االَرمائُح انجُذج وًَكٍ اسرخذايهى فٍ اسرخالص يادج انفُُىل يٍ انًُاِ انصُاعُح نًعايم انفعانُح ، ورنك نًعشفح nrtl, uniquac and unifacذى ذطثُك انُرائج انعًهُح نألَظًح انثالثُح عهً يعادالخ nrtlذى حساب انرشاكُض انًرىلعح حسة ذهك انًعادالخ و يماسَرها يع انُرائج انعًهُح ووجذ اٌ يعادنح . انًعايالخ انثُائُح نرهك انًعادالخ يع انذوال انشَاضُح نرمهُم َرائج انفشق تٍُ انمُى انُظشَح و انعًهُح نًعايم انرىصَع َعطٍ افضم انُرائج حُث إٌ يعذل انخطأ فٍ يخطظ لاتهُح % . 10.776ويعذل انخطأ فٍ َسثح انرىصَع تحذود % 1.436راتح تحذود اإل 26-35 al-khwarizmi engineering journal,vol. 12, no. 1, p.p. experimental study of the effect of condenser tubes distribution for department of (received abstract the performance of a condenser in a domestic refrigerator design consisted of number of loops as elliptical shape was conducted with a refrigerator designed to work with hfc liters of water). in particular, the effects of shape change of the condenser were very important in heat transfer enhancement and reduce of the frictional loss as shown that compressor work decreases with elliptical condenser consumption decreases also. the performance of household refrigerator with was better than that of the conventional instead of the conventional air cooled condenser in a domestic refrigeration system. keywords: household refrigerator, no 1. introduction a refrigerator condenser is one of the main operational components that make up the cooling system on a standard refrigerator. wire on tube heat exchanger has been used in refrigerating and air-conditioning systems for many decades. conventional condenser consists of a steel tube bended into a single passage serpentine shape, with wires spot welded perpendicular on both sides. condensers may be assembled with tubes in a vertical or horizontal position and the air movement can be forced or natural. thermal performances of various kinds of wire on tube heat exchanger have been reported by many research works. the report of witzell and fontaine [1] studied condenser, got correction for condenser, and concluded that any additional of wire on the external surface of condenser did not increase the rate of heat transfer from condenser. kirshbaum and cha [2] modified program developed previously to optimize condenser size with respect to surface khwarizmi engineering journal,vol. 12, no. 1, p.p. 2635 (2016) experimental study of the effect of condenser tubes distribution for domestic refrigerator dheya ghanim mutasher of mechanical engineering / university of technology email: dheya_ghanim@yahoo.com (received 21 may 2015; accepted 3 november 2015) condenser in a domestic refrigerator system without wires and a condenser number of loops as elliptical shape is investigated experimentally in this work rator designed to work with hfc134a, under no load and with loads of water). in particular, the effects of shape change of the condenser were very important in heat transfer the frictional loss as a result of reducing the pressure drop in the condenser. the results decreases with elliptical condenser about (8.6% to 11.3%) performance of household refrigerator with an elliptical condenser without fins conventional condenser without fins. therefore, the elliptical condenser can cooled condenser in a domestic refrigeration system. refrigerator, no wires tube conventional condenser, elliptical condenser, heat transfer is one of the main components that make up the on a standard refrigerator. wire on tube heat exchanger has been used in conditioning systems for many decades. conventional condenser consists of a steel tube bended into a singlepassage serpentine shape, with wires spot endicular on both sides. condensers may be assembled with tubes in a vertical or horizontal position and the air movement can be forced or natural. the thermal performances of various kinds of wire on tube heat exchanger have been reported by the report of witzell studied condenser, got a correction for condenser, and concluded that any additional of wire on the external surface of condenser did not increase the rate of heat kirshbaum and chato modified program developed previously to optimize condenser size with respect to surface area. also developed a new method of modeling, pipe bends incorporating a new pressure drop correlation. lee et al. [3 presented experiments to obtain the cor on the air-side heat transfer coefficient of a single layer wire-on-tube heat exc wilson et al. [4] investigated experimentally the effect of tube profile change from round to flat shape on condensation heat transfer coefficient. melo et experimentally the effects of the gaps between the refrigerator and the back, side and bottom walls of the test section. the results proved that the condenser performance is strongly affected by its position in relation to the adjacent surfaces. choi et al. [6] introduced the new design wire woven heat exchanger using small tube diameter. ahmed and hayder [7] introduced the present modeling of wire and tube condensers that commonly used in vapour compression cycle based on domestic refrigeration. the modeling results showed the effect of mass flow rate, pressure, refrigerant temperature and ambient temperature on the al-khwarizmi engineering journal (2016) experimental study of the effect of condenser tubes distribution university of technology a condenser with a novel is investigated experimentally in this work. the experiment 134a, under no load and with loads of (1.5,3 and 12 of water). in particular, the effects of shape change of the condenser were very important in heat transfer he condenser. the results about (8.6% to 11.3%), and then the power lliptical condenser without fins elliptical condenser can be used ondenser, heat transfer area. also developed a new method of pipe bends incorporating a new pressure drop correlation. lee et al. [3] presented experiments to obtain the correlation side heat transfer coefficient of a tube heat exchanger. investigated experimentally effect of tube profile change from round to flat shape on condensation heat transfer al. [5] studied experimentally the effects of the gaps between the refrigerator and the back, side and bottom walls of the test section. the results proved that the condenser performance is strongly affected by its position in relation to the adjacent choi et al. [6] introduced the new re woven heat exchanger using small ahmed and hayder [7] introduced the present modeling of wire and tube condensers that commonly used in a vapour compression cycle based on domestic refrigeration. the modeling results showed the effect of mass flow rate, pressure, refrigerant temperature and ambient temperature on the dheya ghanim mutasher al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 2635(2016) 27 performance of condenser. gupta et al. [8] used a method such as tilting of the condenser tube with respect to the horizontal and calculating the heat transfer rate and the amount of heat transfer increased by providing some angle of inclination from the horizontal. they observed with use of convergent divergent construction of the condenser can enhance the heat transfer rate. sahu et al. [9] presented an experimental analysis of domestic refrigeration system by using wire-on-tube condenser with different spacing of wire also with different operating parameters like heat transfer rate, condenser pressure and condenser temperature. however, all of the previous work used wire -ontube heat exchanger, solid metal wire as an extended surface. an improvement in the efficiency of household refrigeration systems contributes significantly to a reduction in the world consumption of energy and also to a reduction in the global warming. improving heat transfer effectiveness or/and controlling pressure losses requires novel techniques to develop systems of progressively higher heat transfer performance. in the present paper, condenser tube is arranged in elliptical shape without fins with natural air movement will be considered. there is working fluid such as refrigerant flowing inside the tube, while the ambient air is directed across the outside surface of the tube panel and compared with conventional no wires tube condenser. the thermal characteristics of a newly-designed and the no wire tube heat exchanger have been investigated. 2. analysis the considered heat exchanger consists of a tube bent into a serpentine shape with wires symmetrically welded to both sides in a direction normal to the tubes were cut and removed from the condenser, as shown in figure (1a). from the heat transfer point of view, the exchanger is assumed to be made up of a multiplicity of horizontal tubes. first, the pipe bend pressure drop occurs in conventional condenser causing the frictional pressure drop. in this study, the new design by taking the elliptical condenser instead of no-wire tube condenser has been presented. when the compressor provides the vapor of refrigerant with high pressure and temperature to the condenser, the vapor of refrigerant starts up and down with a first loop from the outer to the inner and continues rotating moving in the rest of the loops and finally delivers the flow to the capillary tube. however, for a better understanding of the work on the new model of condenser, see the figure (1b). heat transfer rate at evaporator or refrigeration capacity, qe is given by: qe = m (h1− h4) …(1) where, m is the refrigerant mass flow rate in kg/s, h1 and h4 are the specific enthalpies (kj/kg) at the exit and inlet to the evaporator, respectively. (h1−h4) is known as specific refrigeration effect or simply refrigeration effect, which is equal to the heat transferred at the evaporator per kilogram of refrigerant. power input to the compressor or work of compression wc is given by: wc = m (h2 − h1) … (2) where, h2 and h1 are the specific enthalpies (kj/kg) at the exit and inlet to the compressor, respectively. (h2 − h1) is known as specific work of compression, which is equal to the work input to the compressor per kilogram of refrigerant. heat transfer rate at condenser, qc is given by: qc =m(h2 − h3) …(3) where, h3 and h2 are the specific enthalpies (kj/kg) at the exit and inlet to the condenser, respectively. for the isenthalpic expansion process, h=const. is given by: h3=h4 …(4) the exit condition of the expansion device lies in the two-phase region, hence applying the definition of quality (or dryness fraction), we can write: h4 = (1 − x4) hf,e + (x4*hg,e) = hf +(x4*hfg ) …(5) for mass flow rate, [m] is given by: measurement of the electrical energy input, e allows the mass flow rate to be determined from the simple relationship: e – h = ( hout hin ) * m …(6) where h are the enthalpy values, per unit mass of the refrigerant. these values are known from the temperature and pressure measurements through the inlet and outlet of the compressor. the heat loss h, expressed as a percentage of e, is between 5 and 7% for most compressor types. the coefficient of performance, [c.o.p] is given by: c.o.p = qe / wc …(7) dheya ghanim mutasher al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 2635(2016) 28 fig. 1(a). schematic of no-wire tube type (b) elliptical type condenser. 3. experimental setup the system was manufactured as elliptical shape condenser instead of conventional condenser without wires. the experimental setup of the test unit and apparatus is shown in figure 2. the refrigerator specifications are given in table 1. table 1, refrigerator specifications. model -tetn1600 concord voltage, current and frequency 220v , 0.8a and 50hz gross capacity 190l compressor type hermetic, hye69yg, hi tech, 1ph, r134a huayi compressor co.ltd. refrigerant hfc134a charged mass 140g no of door 2 condenser types no wire tube condenser and elliptical condenser tube material steel length of tube for both type 19.25m diameter of the tube 4mm distance between the tube (pitch) 35mm fig. 2. experimental setup of the investigation unit and apparatus. 3.1. experimental procedure schematic diagram of the experimental apparatus is shown in figure (3a and b). the domestic refrigerator consists of an evaporator, elliptical air-cooled condenser and hermetically sealed reciprocating compressor. the refrigerator was instrumented with one low pressure gauge (lpg) type p&m located at the inlet of the compressor for measuring the suction pressure reads from 30cm hg to 18 kg/cm2. high pressure gauge (hpg) reads from 0 to 35kg/cm2, two located at compressor and condenser outlet. eight k-type calibrating thermocouples of 2m length (each) were used for local surface temperatures and connected to data logger. the tc-08 from pico, england with 8 channels thermocouples measurements units, which can measure and record temperatures ranging from –270°c to +1820°c. picolog is a powerful and flexible data acquisition program designed for collecting, analyzing, and displaying data over long or short periods of time. as per the refrigerator manufacturer recommendation, quantity of the required charge for hfc134a is vacuum pump data logger charging system condenser inlet pressure suction pressure condenser outlet pressure digital thermometer energy meter thermocouple dheya ghanim mutasher al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 2635(2016) 29 140g. in the experiment, refrigerant charge is 10% higher due to the presence of instruments and connecting lines. an experimental system was evacuated with the help of a vacuum pump to remove the moisture and charged with the aid of the charging system. during the experiment, the ambient temperature was 29 ± 2oc. the experimental procedures were repeated, and the readings from the various modes were taken. service port was installed at the compressor inlet for charging and discharging the refrigerant. the experiment was conducted on the domestic refrigerator at four load conditions namely, (no load, 1.5, 3 and 12 litter of water put in the freezer compartment). at each load condition, the temperature and pressure at salient points were noted down for one second interval, recorded by the data logger connected to the laptop. the experiment was done until steady state conditions were attained in most the temperatures down. the energy consumption of the system was measured by using plug-in mains power and energy monitor (model 2000mu includes 7 precision digital meter) and the lcd display shows all meter readings which include volt, current, watt, frequency, power factor, and volt ampere (va), it starts to accumulate kilowatt hour (kwh) and its duration time (hour) after power on. the typical accuracy for voltage is in the range of 190v250v; and for current is in the range of 0.2a15a. the input volt to the compressor is regulating by fridge stabilizer upto 300 ltrs. (165-280 v) (2 amp.). the performance of the refrigerator with conventional condenser without fins and of the elliptical condenser is evaluated then the test results of two types were compared fig. 3a. schematic diagram of the investigation unit and apparatus. p1, p2, p3, pressure gauges. t1 to t8, thermocouples. t1: compressor outlet temp. t2: condenser outlet temp. t3: evaporator outlet temp. t4: freezer compartment temp. t5: food compartment temp. t6: upper condenser temp. t7: middle condenser temp. t8: lower condenser temp. capillary tube t2 compressor stabilizer energy meter p1 t4 t6 t7 t5 t8 t3 t1 data logger laptop hp pavilion p3 p2 e lliptical c ondenser evaporator dheya ghanim mutasher al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 2635(2016) 30 (a) (b) fig. 3b.(a) shows the process path on a pressure–enthalpy (p– h) diagram, and (b)shows a schematic diagram of the process equipment. 4. results and discussions figure 4. gives the comparison of the temperature at the inlet and outlet of the condenser for two types of conventional and elliptical condensers with steady state condition. for all load conditions, the outlet temperature from the compressor (t1) was greater for the conventional condenser without fins than elliptical condenser because the condenser inlet pressure was higher for conventional condenser than that for elliptical one. also the work done by the compressor is decreased with elliptical condenser, and then the power consumption also decreases. this figure shows that the temperature difference about the elliptical condenser is smaller than the conventional one. load (litter) 0.0 1.5 3.0 4.5 6.0 7.5 9.0 10.5 12.0 t em p e ra tu re (o c ) 30 35 40 45 50 55 60 65 70 75 80 85 90 t1 conventional t2 conventional t1 elliptical t2 elliptical fig. 4. variation the inlet and outlet temperature of the condenser with load. figure 5. shows that for all load conditions, the average temperature of the condenser was greater for the conventional condenser without fins than elliptical condensers at steady state condition. this is due to the pressure drop for conventional condenser was higher than that for the elliptical condenser, then increasing the frictional losses as a result of elbow of the conventional condenser. also the work done by the compressor increases with conventional condenser without fins, and then the power consumption also increases. these results confirmed that the performance of household refrigerator with elliptical condenser was better than that of the conventional condenser. 0.0 1.5 3.0 4.5 6.0 7.5 9.0 10.5 12.0 t a vg . (o c ) 38 40 42 44 46 48 conventional elliptical load (litter) fig. 5. variation of the average temperature at the surface of the condenser (t6,t7 and t8) with load. figure 6. (a,b,c and d) reveals a comparison of the transient temperature at the inlet and outlet of the condenser for conventional and elliptical condensers. for all load conditions, the temperature difference through the elliptical condenser evaporator capillary tube compressor 1 2 4 3 pcond. pevap. enthalpy pressure 3 1 2 4 dheya ghanim mutasher al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 2635(2016) 31 condenser was less than the conventional condenser without fins. this is contributed to developed turbulences inside the rotating flows in the tube and increasing the velocity of the flow as a result of changing the shape of the condenser to elliptical that resulted in the increase of the dissipation of heat. figure 6. (e,f,g and h) manifests the temperature at the surface of the condenser. for low load conditions, the surface temperature of the condenser at the upper, middle and lower (t6,t7 and t8) was converge for both types. at high load conditions, the surface temperature was nonuniform for the conventional condenser while in elliptical condenser, the temperature at these locations converge where flow characteristics are the same for each region of the condenser. this is ascribed to that the pressure drop through the condenser was low and that means the heat dissipation from the elliptical condenser was uniform. without load time (s) 0 2000 4000 6000 8000 10000 12000 14000 t em p er at u re (o c ) 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 t1 conventional t2 conventional t1 elliptical t2 elliptical without load time (s) 0 2000 4000 6000 8000 10000 12000 14000 t e m p er at u re (o c ) 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 t6 conventional t7 conventional t8 conventional t6 elliptical t7 elliptical t8 elliptical (a) (e) 1.5 litter time (s) 0 2000 4000 6000 8000 10000 12000 14000 t em p er at ur e (o c ) 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 t1 conventional t2 conventional t1 elliptical t2 elliptical 1.5 litter time (s) 0 2000 4000 6000 8000 10000 12000 14000 t em p er a tu re (o c ) 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 t6 conventional t7 conventional t8 conventional t6 elliptical t7 elliptical t8 elliptical (b) (f) 3 litter time (s) 0 2000 4000 6000 8000 10000 12000 14000 t e m pe ra tu re (o c ) 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 t1 conventional t2 conventional t1 elliptical t2 elliptical 3 litter time (s) 0 2000 4000 6000 8000 10000 12000 14000 t e m pe ra tu re (o c ) 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 t6 conventional t7 conventional t8 conventional t6 elliptical t7 elliptical t8 elliptical (c) (g) dheya ghanim mutasher al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 2635(2016) 32 12 litter time (s) 0 5000 10000 15000 20000 t e m p er at ur e (o c ) 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 t1 conventional t2 conventional t1 elliptical t2 elliptical 12 litter time (s) 0 5000 10000 15000 20000 t em p er at ur e (o c ) 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 t6 conventional t7 conventional t8 conventional t6 elliptical t7 elliptical t8 elliptical (d) (h) fig. 6. (a, b, c and d) the variation of temperature with time for inle and outlet of the condenser and (e, f, g and h) the variation of the average temperature at the surface of the condenser (t6,t7 and t8) with all loads. figure 7. (a) and (b) illustrates the comparison of the current and pressure for two types of condensers at a steady state condition . for all load conditions, the current was low for the elliptical condenser compared to the conventional condenser without fins. that is owing to the decrease of load on the compressor as a result of easily rotating flow in the elliptical condenser. also, the pressure drop for elliptical was less than that for the conventional condenser, due to the decrease of frictional losses as a result of improving the shape of condenser, where can rotate the flow without restriction to the flow in the elliptical condenser. load (litter) 0 2 4 6 8 10 12 14 c ur re nt ( a m p) 0.46 0.48 0.50 0.52 0.54 0.56 0.58 0.60 0.62 0.64 conventional elliptical load (litter) 0.0 1.5 3.0 4.5 6.0 7.5 9.0 10.5 12.0 13.5 p re ss ur e d ro p (b a r) 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 conventional elliptical (a) (b) fig. 7. (a) variation of the current and (b) the pressure drop with all load. figure 8. (a) and (b) shows that the coefficient of performance was higher for the elliptical condenser compared to the conventional one. also, the compressor work with elliptical condenser was lower than that of conventional condenser. that is because of easily rotating flows in the elliptical condenser which can reduce the load on the compressor. dheya ghanim mutasher al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 2635(2016) 33 load (litter) 0.0 1.5 3.0 4.5 6.0 7.5 9.0 10.5 12.0 c .o .p 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 conventional condenser elliptical condenser load (litter) 0.0 1.5 3.0 4.5 6.0 7.5 9.0 10.5 12.0 c om p re ss or w o rk ( w a tt ) 95 100 105 110 115 120 125 130 135 conventional condenser elliptical condenser (a) (b) fig. 8 (a) variation the coefficient of performance and (b) the compressor work with all load. 5. conclusions based on the previous discussion of the obtained results the following conclusions can be extracted. 1the work done by the compressor decreases about (8.6% to 11.3%) with elliptical condenser and then the power consumption also decreases. 22the temperature difference between the inlet and outlet of the condenser is smaller for elliptical condenser than the conventional one. 3developed turbulences inside the rotating flows in the tube and the increasing of velocity of the flow occurred as a result of changing the shape of the condenser to elliptical that resulted in the increase the dissipation of heat. 4the pressure drop through the elliptical condenser was about (0.35 bar) while in the conventional one was about (0.68 bar). 5the heat dissipation from the elliptical condenser was uniform. 6decreases of frictional losses caused as a results of improving shape of the condenser, where can rotate the flow without restriction to the flow in the elliptical condenser. 7the coefficient of performance increases about (4.5% to 11.33%) with elliptical condenser respect to the conventional condenser without fins. 8the performance of household refrigerator with elliptical condenser was better than that of the conventional condenser without fins. 6. references [1] o.w.witzell,w.e.fontaine,what are the heat transfer characteristics of wire and tube condensers .refrigerating engineering, vol. 65, (1957), pp 33–37. [2] d.j.kirshbaum and j. c. chato, optimized design of refrigerant condensers .air conditioning and refrigeration center, university of illinois. , vol. 217, (1996), pp 333–3115. [3] t.h.lee, j.y.yun, j.s.lee,j.j.park,k.s. lee, determination of air side heat transfer coefficient on wire-on-tube type heat exchanger, international journal of heat and mass transfer, vol. 44, (2001), pp 1767–1776. [4] m. j. wilson, t. a. newell, j. c. chato, c. a. ferreira: refrigerant charge, pressure drop, and condensation heat transfer in flatted tubes, in int. j. refrigeration, vol. 26, (2003), pp 442– 451. [5] c.melo, c.arsego, r.maykot, experimental evaluation of wire and tube condensers:confining walls effects, international refrigeration and air conditioning conference, r077, (2004), pp 1–8. [6] s.h. choi, w.h. cho, j.w. kim, j.s. kim, a study on the development of wire woven heat exchanger using small diameter tubes, experimental thermal and fluid science , vol. 28, (2004), pp 153–158. [7] a.a. imran, h.m. jafal, numerical modeling of wire and tube condenser dheya ghanim mutasher al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 2635(2016) 34 used in domestic refrigerators, journal of engineering and development,vol. 13, no. 2, june (2009), issn 1813-7822, pp 1–16. [8] r.m. gupta, s. singh, s. srivastava, performance analysis and calculation of different parameters of condenser using ansys fluent software, international journal of application or innovation in engineering and management (ijaiem), vol. 2, issue 7, issn 2319-4847, (2013), pp 529–534. [9] v. sahu, p.tiwari, k. k. jain, a.tiwari, experimental investigation of the refrigerator condenser by varying the fins spacing of the condenser, international journal of mechanical engineering and robotics (ijmer), issn 2321-5747, vol.1, (2013), pp 9–12. )2016( 2635، ! �� 1، ا���د�12ا������� ا������� ا���ارز� � ���ء ��� ���� 35 1�� "�ز&0 ا��/�. ا��-+, �+*(� ��)���'درا�� "��&%�� $�# " ���ء ��� ���� �����������'&��/ %$# ا�"! �� ا'!�(�ا�+�*(� ا dheya_ghanim@yahoo.com ,-.�: ا1��)-و�/ ا ا��*!� ��45 اداء���# & , ,)�'ن *e d د *d ا��bc7ت >@�? >�<'ي >67 ;+-,.�� :/ ھ8ا ا�.67 اg; h* 45�*ك وj�ون ا < ���k!��. :/ ��mم ا�j5&� ا h* ?�)c� ���g* �&jn oce ?�); p��q رب�+(���ل *)�u-ة ). hfc 134a(اwا p7;و ) ?�w ء ١٢، ٣، ١.٥، > ون���و>@�? _�ص ). ��)*d ا �` -��u; -�n�; ك��(w1ا -a�$_ ?�cb;7-ارة و���45 *"# & ا :/ ;d�$7 ا�)�bل ا���bcd'<45 ? ا��)�cb? ا�".'ط >��<eu :/ ا �cg7* . ان ga�(!�;'hi ا '< k+!����45 ا�.�<'ي w'ا�/ ��ا�@u? ا�8�b; m?، %)١١.٣ا�o % ٨.٦(ط� ا�<�h* ?b, ej اq ��c"($����� *h . وb�ce ا�b رة اk!��اداء ا�j5&� ا ���45 ا�)�cb ي > ون ز4��eا��.-دة . ��45 ا�.�<'ي > ون ز4��e ا:<? *d ا����c5ت ا�)�cb ,� ا���45 ا�.�<'ي > de 1 ا���d ا�)o ام ا, m�8� ���k!���"'اء :/ ��mم ا�j5&� ا�<. al-khwarizmi!! engineering!!! journal al-khwarizmi engineering journal, vol.4 , no.1 , pp 68-79 (2008!) !! evaluation of hydrated lime filler in asphalt mixtures dr. mohammed abbas hasan al-jumaily engineering college university of kufa (received 16 february 2007 ; accepted 26 november 2007) abstract mineral filler is one of important materials and affecting on properties and quality of asphalt mixtures .there are different types of mineral filler depended on cost and quality , the matter encourages us to achieve this study to evaluate hydrated lime filler effects on properties of asphalt mixes related with strength and durability. conventional asphaltic concrete mixtures with portland cement and soft sandstone fillers and mixtures modified with hydrated lime were evaluated for their fundamental engineering properties as defined by marshall properties , index of retained strength , indirect tensile strength , permanent deformation characteristics , and fatigue resistance .a typical dense graded mixture employed in construction of surface course pavement in iraq in accordance with scrb specifications was used .the materials used in this study included mineral aggregate materials (coarse and fine sizes) were originally obtained from najaf sea quarries and two grades of asphalt cements produced from daurah refinery which are d47 and d66 . the physical properties , stiffness modulus and chemical composition are evaluated for the recovered asphalt cement from prepared asphalt mixes containing various filler types .the paper results indicated that the addition of hydrated lime as mineral filler improved the permanent deformation characteristics and fatigue life and the use of hydrated lime will decrease the moisture susceptibility of the asphalt mixtures. key word: hydrated lime, mineral filler, chemical composition, retained strength index, indirect tensile strength, indirect tensile creep, indirect tensile fatigue, rutting distress, absolute viscosity, stiffness modulus. introduction permanent deformation, fatigue and moisture damage are common distresses found in asphalt pavements today. in many cases , mineral fillers will increase the mixture stiffness. in iraq , the performance of asphalt pavements has deteriorated over the last decade . heavy axle loads coupled with the hot climate and poor drainage systems in middle part of iraq are major contributing factors to the development of severe pavement distresses such as permanent deformation and loss of structure because of moisture damage. the use of lime to reduce moisture sensitivity has been promoted by fhwa for many years (shah,1963). the structure of hydrated lime consists of different size fractions. the larger size fraction performs as a filler and increases the stiffness of the asphalt mixture. the smaller size fraction increases asphalt film thickness enhancing viscosity of the asphalt , and improving the asphalt cohesion and stiffness. adhesion between the aggregate and asphalt increases (dickinson ,1984) , resulting in decreased mixture segregation. the water sensitivity of asphalt mixes treated with hydrated lime and antistrip agents was evaluated previously (kennedy et.al.,1982 and kennedy et. al. , 1991). results from these tests depended on the actual combinations of aggregate , asphalt and additives. however, mohammed abbas al-khwarizmi engineering journal, vol.4 , no. 1 pp 6879 (2008) 69 among the antistrip agents, hydrated lime was most effective in increasing the tensile strength and in improving the water sensitivity of the mixture. this paper presents the results of a comparative study conducted on various asphalt mixes with three different mineral filler types to determine if the use of hydrated lime as a mineral filler leads to any improvement in the fundamental engineering properties. in addition, effect of hydrated lime on physical properties and chemical composition of asphalt cement has been investigated in this study. materials asphalt cement the two grades of asphalt cement used in this work included: (40-50) and(60-70) penetration grade asphalt from daurah refinery .the different physical properties of asphalt cement are evaluated according to astm standards including absolute viscosity (d2171) , standard penetration (d5),ductility (d113), specific gravity (d70) , solubility in trichloroethylene (d2042) and thin-film oven test (d1754). the chemical composition of the asphalt cement is determined by the modified precipitation method of rostler (astm d 4124 ) , in which the asphalt is separated into four fractions (rostler and rostler ,1981) as shown in table 1. the physical properties and chemical composition of the two asphalt types (d47 and d66) as well as state commission of roads and bridges , scrb (scrb, 2003)specifications are presented in table 2 . aggregate and mineral filler properties mineral aggregate materials (coarse and fine sizes) were originally obtained from najaf sea quarries. the aggregate properties are listed in table 3. three different types of mineral filler were used as mineral filler in preparation of various asphalt mixes because these types were available in a large quantity during study period. the hydrated lime filler was obtained from karbala’a factory. the portland cement filler was brought from kufa cement factory . the soft sandstone powder filler was obtained from najaf sea quarries. the physical properties of the mineral filler types are shown in table 4. asphalt concrete mixtures the asphalt concrete mixtures are prepared using crushed gravel and sand with three different mineral fillers and two asphalt cement types . the mid limits of the 12.5 mm nominal maximum size dense gradation in accordance with scrb (scrb, 2003) specification requirements are used in preparing six asphalt mixtures ( two asphalt cements and three mineral fillers) as reported in table 5. the six asphalt mixture types included in this study are coded as shown in table 6 . the optimum asphalt contents (o.a.c) of various asphalt mixtures which were determined from standard marshall mix design in accordance with astm d1559 (astm,2003) are reported in table 7 . also, marshall properties at (o.a.c) and scrb (scrb ,2003) specifications for asphalt mixes used in the construction of surface course are presented in table 7. fundamental test procedure four fundamental tests were conducted to characterize the six mixtures and determining the effects of the hydrated lime mineral filler on the properties of asphalt mixes. three specimens were prepared and the average results are reported for all tests .a brief description of each test is given below: index of retained strength test index of retained strength test is used to evaluate moisture damage of asphalt pavement in accordance with method astm d1075 (astm ,2003). it is one of tests required by scrb (scrb , 2003) specifications to be performed on asphalt mixes used in surface course in addition to marshall tests. this test is intended to measure the loss of cohesion resulting from the action of water on compacted bituminous mixtures containing penetration grade asphalt. a set of six cylindrical specimens 4 in (101.6mm) in diameter by 4 in (101.6mm) in height was prepared for each asphalt mixtures in according with the procedure described in the standard method of test for compressive strength of bituminous mixtures of astm d1074 (astm ,2003). mohammed abbas al-khwarizmi engineering journal, vol.4 , no. 1 pp 6879 (2008) 70 indirect tensile strength test the indirect tensile strength at 25oc is evaluated for cylindrical specimens (101.6mm diameter × 63.5 mm height ) in accordance with astm d4123 (astm,2003). indirect tensile creep test at testing temperature of 40 oc , a compressive stress of 0.138 mpa (20 psi) was applied on the marshall specimen (101.6mm diameter × 63.5 mm height ). the loading times include (3,5,10,100, and 1000 seconds) and rest periods are (2,2,2,4,and 8 minutes). the total permanent strains, εp (in/in) at the end of each rest period were measured. in last loading time (1000 seconds), the creep deformations were measured after 3, 6, 10, 30, 60,100, 300, 600, and 1000 seconds durations. the creep compliance, c (t), at each of these loading durations is calculated as follows: c(t)=є(t)/σo … (1) where: c(t)= creep compliance at (1/mpa), є(t)=vertical strain at loading duration t (mm/mm), and σo = applied stress (mpa) . indirect tensile fatigue test to determine the fatigue resistance of the asphalt concrete samples, this test was conducted at 25oc temperature by using the machine manufactured by the researcher in the highway laboratory in college of engineering in kufa university . the (10 %) of the test failure load obtained from indirect tensile test was used as the peak value of the cyclic load with loading duration of 0.10 second followed by a rest period of 0.90 second was applied to the test specimen (loulizi et.al.,2002) .the number of cycles were monitored through the duration of test and the test was terminated when the specimen reached to failure. 4. discussion of test results the test results obtained from experimental work will be discussed in the following sections effect of mineral filler type on asphalt cement properties and chemical composition to evaluate the effect of mineral filler type on the physical properties and chemical composition of asphalt cement , there is need to recovery the asphalt from asphalt mixture specimens .extraction test was achieved by using a solvent in accordance with the method standardized in astm d 2172 (astm , 2003) to quantitative separation of the aggregate and asphalt cement . the asphalt was then recovered from asphalt-solvent solution (extract) in accordance with the method described in astm d1856 (astm ,2003). the stiffness modulus values of recovered asphalt cement types at temperature of 60 oc and a loading time of 0.02 second were determined by using shell nomographs (bonnaure et. al. ,1977) .three properties of the recovered asphalt cement are evaluated : absolute viscosity , ductility and stiffness modulus .the effect of mineral filler type on these properties are shown in fig.1. (a) absolute viscosity (b) ductility 1000 3000 5000 7000 9000 d47 d66 a bs ol ut e vi sc os ity at 60 (p oi se s) recovered asphalt cement type hydrated lime filler portland cement filler soft sandstone filler o c 60 70 80 90 100 d47 d66 recovered asphalt cement type d uc ti li ty (c m ) hydrated lime filler portland cement filler soft sandstone filler mohammed abbas al-khwarizmi engineering journal, vol.4 , no. 1 pp 6879 (2008) 71 (c) stiffness modulus fig. (1) effect of mineral filler type on asphalt cement properties it can be noticed that recovered asphalt cement from mixes containing hydrated lime as a filler exhibits high absolute viscosity and stiffness values and has low tensile properties represented by low ductility values when compared with other asphalt types. the chemical composition parameter, gaestel index (ig) defined as the ratio of (asphaltenes and saturates ) fractions to (naphthene aromatics and polar aromatics) fractions which is related with asphalt durability (ishai i. ,1995). high values of (ig) refers to reduction in the asphalt durability and asphalt exhibits brittle and hardening behavior. the chemical fractions and gaestel index values of original and recovered asphalt cement types are reported in table 8. the asphalt cement considers durable if the range of (ig) values lie within a range of about (0.4-1.2) (ishai i. ,1995). it may be seen from table 8 that all asphalt cement types fall within this range and have good durability. effect of mineral filler type on marshall stiffness and air voids marshall stiffness (kn/mm) , which is calculated as the ratio between marshall stability and corresponding marshall flow at optimum asphalt content, represents the combination of stability and flow in single value .marshall stiffness gives the indication about the resistance of asphalt mixture to plastic flow resulted from loading. high values of marshall stiffness means the asphalt mixtures have considerable resistance to permanent deformation in case these mixes will be used in construction of pavement. it is well known that percentage of air voids is related to durability of asphalt mixture. the role of mineral filler type in increasing or decreasing of air voids is necessary to be investigation. the effect of mineral filler type on marshall stiffness and air voids is shown in fig. 2. (a) marshall stiffness (b) air voids fig.(2) effect of mineral filler type on marshall stiffness and air voids of asphalt mixes it can be seen from figure that using hydrated lime as a mineral filler increases the mixture stiffness and improving the it durability represented by low air voids percent 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 m a rs h a ll s ti ff n e s s (k n /m m ) asphalt mixture type 3.0 3.2 3.4 3.6 3.8 4.0 4.2 4.4 4.6 4.8 5.0 d47hl d47pc d47ss d66hl d66pc d66ss asphalt mixture type a ir v o id s ( % ) 1.00 1.50 2.00 2.50 3.00 3.50 4.00 4.50 d47 d66 recovered asphalt cement type s ti ff ne ss m od ul us a t 60 (p a) hydrated lime filler portland cement filler soft sandstone filler o c × 10 5 mohammed abbas al-khwarizmi engineering journal, vol.4 , no. 1 pp 6879 (2008) 72 in comparison with using other mineral filler types. effect of mineral filler type on index of retained strength the moisture damage of asphalt concrete mixtures had produced serious distress , reduced performance and increased maintenance for asphalt pavements. scrb (scrb ,2003) specifications require this distress to be checked by performing the index of retained strength percent test . fig. 3 indicates effect of mineral filler type on index of retained strength percent of asphalt mixes fig. (3) effect of mineral filler type on index of retained strength percent of asphalt mixes scrb (scrb, 2003) specifications require the minimum percentage of index of retained strength as 70 % for asphalt mixtures used in a construction of surface course pavement . it can be noticed from fig. 3 that all asphalt mixtures have index of retained strength percent above minimum percentage from test results illustrated in figure , it can be seen that asphalt mixtures prepared from hydrated lime filler has high resistance to moisture damage because they exhibit high percentages of index of retained strength in comparison with other asphalt mixtures. effect of mineral filler type on indirect tensile strength (its) fig. 4 presents the indirect tensile strength (its) test results. in this test , high tensile strength at failure is desirable property for stiff mixtures. for the its test performed at 25oc , the addition of hydrated lime increases the strength for d47hl and d66hl asphalt mixtures. this may be due to the fact that at intermediate temperatures the combined viscosity of the asphalt and minus 0.075 material decreases more in mixtures with other mineral filler types , causing the mixture to lose more of its strength. in other words , the using of the lime filler improved the indirect tensile strength for two asphalt mixtures. fig. (4) effect of mineral filler type on indirect tensile strength of asphalt mixes effect of mineral filler type on rutting distress one of the main types of structural distress which may affect the performance of asphalt concrete pavements is permanent deformation , also known as rutting . rutting develops with an increasing number of axle load applications. rutting is caused by a combination of densification and shear related deformation and may occur in any course of a pavement structure. vesys 5w software program is short for visco elastic pavement system analysis program (kenis et. al. ,1982) and (fhwa , 2003) . it is necessary to mention that the rut depth computed by the 70 75 80 85 90 95 100 d47hl d47pc d47ss d66hl d66pc d66ss asphalt mixture type in d ex o f re ta in ed s tr en g th ( % ) 1000 1250 1500 1750 2000 d47hl d47pc d47ss d66hl d66pc d66ss asphalt mixture type in d ir e c t t e n s ile s tr en g th (k p a ) mohammed abbas al-khwarizmi engineering journal, vol.4 , no. 1 pp 6879 (2008) 73 vesys 5w program is the summation of the permanent deformation values of all courses .therefore , the vesys 5w software program requires the input of material properties of the courses ,the course thicknesses ,traffic data ,and environmental conditions. these input data will be described in the following articles: material properties to obtain input parameters required for the vesys 5w software , an average curve of creep compliance c (t) versus time is constructed on a log-log graph and extrapolated backward to obtain values of c (t) at 0.1 and 0.30 seconds . the total permanent strain versus incremental time of loading is plotted on a log-log graph and the best-fit line is obtained .the intersection of the line with the vertical axis is denoted by i and the slope by s . the permanent deformation properties μ and α are determined as follows: μ=is/ε … ( 2 ) α=1-s … ( 3 ) where ε is the recovered strain which was obtained from resilient modulus test the parameters (α and μ) obtained from the incremental static creep test performed on asphalt mixture are used as input into the vesys 5w software to estimate the rut depth of a specific pavement structure using properties of different asphalt mixtures. resilient modulus values, alpha (α) and gnu (µ) parameters for binder, base, subbase and subgrade courses are taken as a default values [fujie and tom (2002)] and [mohammed and michael (1999)] while corresponding values for the surface course were determined from laboratory tests. average resilient modulus values (mpa) of various asphalt mixtures which were obtained by conducting the resilient modulus test on three marshall specimens for different asphalt mixes. the specimens were tested at 25, 40 and 60 oc temperatures according to a modified astm d4123 (astm,2003). the conventional flexible pavement structures are layered systems , and consist of a surface course , binder course , base course ,subbase course and subgrade . the selected pavement structure consists of five courses with material properties and thicknesses are reported in table 9. the variability coefficients of the course properties were taken as 10, 10, 15, 15 and 20 % for the surface, binder, base, subbase and subgrade courses respectively. traffic loading initially an equivalent 80 kn (18 kip) single axle load (esal) with dual tires was adopted . traffic loading is assumed to be one million esal at end of first year of pavement service life . the dual tires are spaced 13.57 inch (34.5 cm) apart with tire pressure of 80 psi (552 kpa) and radius contact area of 4.25 inch (10.8 cm).tire contact area depends on contact pressure .thus , the contact pressure was assumed equal to the tire pressure (no effect of tire wall ) . the use of esal is based on the results of experiments that have been shown that the effect of any load on the performance of a pavement can be represented in terms of the number of single applications of (esal). annual growth rate is assumed to be 10 percent. environmental conditions many environmental conditions influence the performance of the flexible pavement. the only environmental effect that is included in the developed model is the temperature of the asphalt course. changes in the temperature of the asphalt course affect the elastic and viscous properties of the asphalt. three temperatures (25 ,40 and 60 oc) were used in estimation of rut depth within selected pavement structure. rut depth values the system rutting formulation treats the pavement system as a whole and first calculates an equivalent set of pavement system permanent deformation parameters (α sys and μ sys) which are determined as functions of load repetitions by least square regression analysis .vesys 5w software program is applied to estimate rut depth in selected pavement structure by using resilient modulus values , three testing temperatures . fig. 5 below presents the rut depth values of various asphalt mixtures at end of 10 years of analysis time. mohammed abbas al-khwarizmi engineering journal, vol.4 , no. 1 pp 6879 (2008) 74 10 15 20 25 30 35 40 d47hld47pcd47ssd66hld66pcd66ss r u t de p th (m m ) asphalt mixture type fig. (5) effect of mineral filler type on rut depth values of asphalt mixes when comparing the rut depth results showed in fig. 5 , it is noted that the addition of hydrated lime improved the performance indicators with low rut depth values . effect of mineral filler type on indirect tensile fatigue test results fatigue cracks are caused by repeated traffic loading and it occurs in asphalt pavements when repeated stress or strain having a maximum value generally less than the ultimate strength of the material (yoder and witczak ,1975) . the results of the indirect tensile fatigue test are presented in fig. 6 . while evaluating the fatigue resistance of asphalt concrete mixes , the number of cycles to failure are used as performance indicators.a high number of cycles to failure are the desired properties. fig. 6: effect of mineral filler type on number of cycle to failure of asphalt mixes the results of the fatigue test indicate that the addition of hydrated lime as a filler increased the fatigue resistance of the mixes. the d66hl mixture was the mix that showed the highest endurance to the repeated cyclic loading of the fatigue test. 5. conclusions within the limitations of materials and test procedures used in this work, the following are concluded: 1. the smaller size fractions of hydrated lime enhancing the absolute viscosity , and improving the asphalt durability and stiffness of the recovered asphalt from asphalt concrete mixture containing hydrated lime as a filler. 2. the hydrated lime is effective in increasing the moisture damage resistance of the mixture, thereby providing pavements that are highly strip resistance. 3. the asphalt mixes with hydrated lime showed improved stiffening and durability properties when incorporated into the mixture. 4. the tensile strength are highest for the asphalt concrete mixes containing hydrated lime fillers than mixes designed with other mineral filler types. 5. the research results revealed that the hydrated lime fillers can have an effect on the rutting susceptibility and fatigue life of flexible pavements , and the use of hydrated lime can improve resistance of the mixes to rutting and fatigue cracking distresses. table 1: chemical composition of asphalt cement fraction chemical reactivity asphaltenes – a low polar aromatics –pa high napthene aromatics -na high saturates -s low 100000 400000 700000 1000000 1300000 1600000 d47hl d47pc d47ss d66hl d66pc d66ss asphalt mixture type n u m b e r o f c y c le t o f a il u re mohammed abbas al-khwarizmi engineering journal, vol.4 , no. 1 pp 6879 (2008) 75 table 2 : the physical properties chemical composition of asphalt cement types property daurah (40-50) daurah (60-70) scrb specifications (40-50) (60-70) standard penetration ,1/10 mm 47 66 40-50 60-70 absolute viscosity at 60 oc, poises 2033 1340 ------------ductility ( 25 oc , 5 cm/min ),cm >100 >100 =>100 =>100 specific gravity at 25oc 1.035 1.03 -------------solubility in trichloroethylene ,% 99.72 99.9 >99 >99 mass loss , % 0.35 0.58 <0.75 <0.80 residue from thin film oven test -retained penetration,% of original -ductility ( 25 oc,5 cm /min.), cm 65 75 61 92 >55 >25 >52 >50 chemical composition , % asphaltenes – a 20.03 18.31 polar aromatics –pa 35.42 37.08 napthene aromatics -na 24.20 25.37 saturates -s 20.35 19.24 table 3 : coarse and fine aggregate properties property value test method specification source specification requirements coarse aggregate sieve size (mm) 12.5 to 2.36 scrb ------------bulk specific gravity 2.632 astm c127 ---------------------percent wear, los angeles (%) 19.2 astm c535 scrb not more than 30 % % crushed pieces (one face) 96 ---------scrb at least 90% by weight of material soundness, total weight loss percent 3 astm c88 scrb not more than 12 % fine aggregate sieve size (mm) 2.36 to 0.075 scrb --------bulk specific gravity 2.676 astm c128 -------------soundness , total weight loss percent 4.6 astm c88 scrb not more than 12 % mohammed abbas al-khwarizmi engineering journal, vol.4 , no. 1 pp 6879 (2008) 76 table 4: physical properties of mineral filler types property test method result hydrated lime passing sieve no. 200, % --------------100 specific gravity astm c128 2.785 plasticity index aashto t90 1.5 portland cement passing sieve no. 200, % --------------96 specific gravity astm c128 3.15 surface area (m2/kg) 357.82 soft sandstone specific gravity astm c128 2.653 plasticity index aashto t90 3.2 table 5: selected gradation of aggregate sieve size (mm) 19 12.5 9.5 4.75 2.36 0.30 0.075 % passing 100 95 83 59 43 13 7 table 6: the code for the six asphalt mixture types asphalt mixture code description d47hl daurah 47 pen.asphalt with hydrated lime filler d47pc daurah 47 pen.asphalt with portland cement filler d47ss daurah 47 pen.asphalt with soft sandstone filler d66hl daurah 66 pen.asphalt with hydrated lime filler d66pc daurah 66 pen.asphalt with portland cement filler d66ss daurah 66 pen.asphalt with soft sandstone filler table 7 : marshall properties of different asphalt mixture types at optimum asphalt content scrb specifications asphalt mixture type property d66ssd66pcd66hld47ssd47pcd47hl min. 8 kn 9.58.610.712.911.314.4marshall stability (kn) 2-4 mm3.43.73.13.23.62.8marshall flow(mm) 3-5 %4.24.03.54.64.33.8voids in total mix (%) min. 1415.915.114.816.916.615.7 voids in mineral aggregate (%) 65-85 %73.673.576.472.874.175.8 voids filled with asphalt (%) 4-6 %5.484.75.205.034.95.36 optimum asphalt content (%) mohammed abbas al-khwarizmi engineering journal, vol.4 , no. 1 pp 6879 (2008) 77 table 8: chemical fractions and gaestel index values of original and recovered asphalt cement types asphalt cement original d47 original d66 recovered asphalt cement types d47hl d47pc d47ss d66hl d66pc d66ss % a 20.03 18.31 26.29 23.77 22.61 23.24 21.48 20.07 % p.a. 35.42 37.08 22.45 33.65 22.92 20.19 38.56 36.41 % n.a. 24.20 25.37 31.80 22.61 34.44 38.35 21.59 24.83 % s 20.35 19.24 19.46 19.97 20.03 18.22 18.37 18.69 ig 0.68 0.60 0.84 0.78 0.74 0.71 0.66 0.63 table 9: material properties of pavement structure courses material properties surface binder base subbase subgrade resilient modulus (psi) variable 143000 66000 10000 5000 poisson’s ratio 0.35 0.35 0.35 0.40 0.45 thickness (cm) 5 8 15 25 infinity permanent deformation properties alpha (α) variable 0.66 0.65 0.88 0.77 gnu (µ) variable 0.12 0.15 0.03 0.04 references 1.aashto,(1989),"standard specification for transportation materials and methods of sampling and testing ", american association of state highway and transportation officials, 14th edition, part i, part ii,washington, d.c., u.s.a 2. astm standards, (2003), "roads and paving materials" , annual book of the american society for testing and materials standards , section 4 ,vol. 04-03. 3. bonnaure , f., g. gest , a. gravots , and p. uge , (1977), " a new method of predicting the stiffness of asphalt paving mixtures ", proceeding of association of asphalt paving technologists , vol.46 , pp.64 – 100. 4. fhwa , (2003) ,"vesys 5w ’s user manual ", federal highway administration office (fhwa)of infrastructure research and development ,truck pavement interaction program, june 26, washington, d.c. 5. fujie ,z. and tom, s.,(2002)," vesys 5 rutting model calibrations with local accelerated pavement test data and associated implementation " , texas department of transportation in cooperation with the u.s. department of transportation federal highway administration , september, report 9-1502-01-2 , project number 9-1502. 6. ishai i. ,(1995), "long term laboratory and field behavior of ppa asphalt cement blends ", proceedings of the association of asphalt paving technologists, vol. 64, pp.306-337. 7.kenis, w.j., j.a. sherwood, and t.f. mcmahon,(1982), "verification and application of the vesys structural subsystem", proceedings of the fifth international conference on the structural design of asphalt pavements, the netherlands, 1982 , vol.1, pp. 333-346. 8. kennedy , thomas w., roberts, freddy l., and lee , kang w., (1982), " evaluation of moisture susceptibility of asphalt mixtures mohammed abbas al-khwarizmi engineering journal, vol.4 , no. 1 pp 6879 (2008) 78 using the texas freeze-thaw pedestal test" ,proceeding of association of asphalt paving technologists , vol.51 , pp.327 – 341. 9. kennedy , thomas w. , and ping , w. virgil , (1991), " an evaluation of effectiveness of antistripping additives in protecting asphalt mixtures from moisture damage " , annual meeting of the association of asphalt paving technologists , march 4-6 . 10. loulizi, a., al-qadi, i.l., lahour, s., and freeman, t.e., (2002), "measurement of vertical compressive stress pulse in flexible pavements and its representation for dynamic loading", transportation research board, paper no.02-2376. 11. mohammed , m. e. and michael , s.m.,(1999), " effect of aggregate gradation on the rutting potential of superpave mixes " , transportation research board , 78th annual meeting , january 10-14 , washington , d.c. 12. rostler and rostler , k.,(1981), "basic considerations in asphalt research pertaining to durability ", proceeding of association of asphalt paving technologists , vol.50. 13. shah ,s.c., (1963) , " asphaltic concrete pavement survey " , louisiana transportation research center report no.9 , baton rouge , louisiana , 1963. 14. state commission of roads and bridges (scrb), (2003), "general specification for roads and bridges", republic of iraq, ministry of housing and construction, department of planning and studies, baghdad, revised edition ,addendum no.3. 15. yoder , e . j. and witczak , m. w. , (1975) , " principles of pavement design " , second edition , john wiley and sons , new york. !! mohammed abbas al-khwarizmi engineering journal, vol.4 , no. 1 pp 6879 (2008) 79 تقییم الجیر المطفأ كمادة مالئة في الخلطات االسفلتیة محمد عباس حسن الجمیلي .د قسم الھندسة المدنیة جامعة الكوفة -كلیة الھندسة :الخـــالصــة ا ال ةعلى خواص ونوعی ةالمؤثرو ةالمھم دالمادة المالئة المعدنیة ھي احد الموا فلتیة تخلط اك , اإلس د ھن ة وتوج واع مختلف ن أن م ذه الدراس إجراء على االمر الذي شجع ، ةوالنوعی ةالكلف فیما بینھا من ناحیة المالئة متباینةالمواد أثیرا تل ةھ یم ت أ تقی ر المطف ى الجی عل ال اإلسفلتیة من حیث مقاومة تخواص الخلطا ة األحم م تح .و متان فلتیة ت ات اإلس یر الخلط ة ض تخدام التقلیدی منت باس د اس و بورتالن رى مطحون كمادة المالئة و يحجر رمل ة أخ ھا معدل یم خواص أ لتق ر المطف ل یةھندس ال الجی ن قب ة م ي ُمَعرَّف ا ھ یِة كم واص األساس خ ترجعة المقاومة مارشال، دلیل ة ، المس ّد ا مقاوم ائص اللش ر، خص ر مباش و الغی ة ، ويدائم ه تش ل مقاوم م .الكل تخدام ت درج اس ف ال الت كثی راق لتحضیر الخلطة و المستخدم في انشاء مثاليال ي الع طحیة ف فات الطبقة الس ب مواص ذه . (scrb)بموج ي ھ تعملة ف واد ألمس الم الع بح ) مقاسات خشنة وناعمة( ةركام معدنی ادتضمنت مو ةالدراس ف رتم الحصول علیھا من مق ن ونج ان م فلت نوع ن اإلس تج م المن فى دورة مص ا ال یم .d66, d47 وھم م تقی ة ت واص الفیزیائی ن الخ تعادة م فلت المس اوي لإلس ب الكیمی الدة و التركی ل الص ومعام ة .المالئة المختلفة المحضرة و التي تحتوي على المواد اإلسفلتیةالخلطات ادة مالئ أ كم ر المطف افَة الجی أّن إض أظھرت نتائج البحث ب .للخلطات اإلسفلتیةالجیر المطفأ یقلل من حساسیة الرطوبة استعمال كذلك الدائمي وعمر الكلل و ِهالتشو صَن خصائَحّس 2 . 0 2 . 5 3 . 0 3 . 5 4 . 0 4 . 5 5 . 0 5 . 5 m a r s h a l l s t i f f n e s s ( k n / m m ) asphalt mixture type 70 75 80 85 90 95 100 d47hl d47pc d47ss d66hl d66pc d66ss asphalt mixture type index of retained strength (%) 1000 1250 1500 1750 2000 d47hl d47pc d47ss d66hl d66pc d66ss asphalt mixture type indirect tensile strength (kpa) 1000 3000 5000 7000 9000 d 47 d 66 a b s o l u t e v i s c o s i t y a t 6 0 ( p o i s e s ) recovered asphalt cement type hydrated lime filler portland cement filler soft sandstone filler 100000 400000 700000 1000000 1300000 1600000 d47hld47pcd47ssd66hld66pcd66ss asphalt mixture type number of cycle to failure 70 75 80 85 90 95 100 d47hld47pcd47ssd66hld66pcd66ss asphalt mixture type index of retained strength (%) 3.0 3.2 3.4 3.6 3.8 4.0 4.2 4.4 4.6 4.8 5.0 d47hld47pcd47ssd66hld66pcd66ss asphalt mixture type air voids (%) 60 70 80 90 100 d47d66 recovered asphalt cement type ductility(cm) hydrated lime filler portland cement filler soft sandstone filler 1.00 1.50 2.00 2.50 3.00 3.50 4.00 4.50 d47d66 recovered asphalt cement type stiffness modulus at 60 ( pa ) hydrated lime fillerportland cement filler soft sandstone filler 1000 1250 1500 1750 2000 d47hl d47pc d47ss d66hl d66pc d66ss asphalt mixture type indirect tensile strength (kpa) 1000 3000 5000 7000 9000 d 47 d 66 a b s o l u t e v i s c o s i t y a t 6 0 ( p o i s e s ) recovered asphalt cement type hydrated lime filler portland cement filler soft sandstone filler 70 75 80 85 90 95 100 d47hl d47pc d47ss d66hl d66pc d66ss asphalt mixture type index of retained strength (%) 2 . 0 2 . 5 3 . 0 3 . 5 4 . 0 4 . 5 5 . 0 5 . 5 m a r s h a l l s t i f f n e s s ( k n / m m ) asphalt mixture type 1000 1250 1500 1750 2000 d47hld47pcd47ssd66hld66pcd66ss asphalt mixture type indirect tensile strength (kpa) 10 15 20 25 30 35 40 d 47 hl d 47 pc d 47 ss d 66 hl d 66 pc d 66 ss r u t d e p t h ( m m ) asphalt mixture type تخطيط1 d47hl d47pc d47ss d66hl d66pc d66ss asphalt mixture type marshall stiffness (kn/mm) 5.14 3.14 4.03 3.45 2.32 2.79 ورقة1 hydrated lime filler portland cement filler soft sandstone filler d47 7230 5100 4618 d66 4492 3851 2663 ورقة1 hydrated lime filler portland cement filler soft sandstone filler recovered asphalt cement type absolute viscosity at 60 c (poises) ورقة2 hydrated lime filler portland cement filler soft sandstone filler d47 4.27 2.93 3.51 d66 2.66 1.85 2.09 ورقة2 hydrated lime filler portland cement filler soft sandstone filler recovered asphalt cement type stiffness modulus at 60 c (pa) ورقة4 d47hl 3.8 d47pc 4.3 d47ss 4.6 d66hl 3.5 d66pc 4 d66ss 4.2 ورقة4 asphalt mixture type air voids (%) ورقة3 d47hl 5.14 d47pc 3.14 d47ss 4.03 d66hl 3.45 d66pc 2.32 d66ss 2.79 ورقة3 asphalt mixture type marshall stiffness (kn/mm) تخطيط2 d47hl d47pc d47ss d66hl d66pc d66ss asphalt mixture type rut depth (mm) 11.3 20.8 17.6 27.8 36.5 32.4 ورقة1 hydrated lime filler portland cement filler soft sandstone filler d47 7230 5100 4618 d66 4492 3851 2663 ورقة1 hydrated lime filler portland cement filler soft sandstone filler recovered asphalt cement type absolute viscosity at 60 c (poises) ورقة2 hydrated lime filler portland cement filler soft sandstone filler d47 4.27 2.93 3.51 d66 2.66 1.85 2.09 ورقة2 hydrated lime filler portland cement filler soft sandstone filler recovered asphalt cement type stiffness modulus at 60 c (pa) ورقة4 d47hl 11.3 d47pc 20.8 d47ss 17.6 d66hl 27.8 d66pc 36.5 d66ss 32.4 ورقة4 asphalt mixture type rut depth (mm) ورقة5 d47hl 21.3 d47pc d47ss d66hl d66pc d66ss ورقة3 d47hl 1951 d47pc 1643 d47ss 1486 d66hl 1334 d66pc 1202 d66ss 1111 ورقة3 asphalt mixture type marshall stiffness (kn/mm) تخطيط3 d47hl d47pc d47ss d66hl d66pc d66ss asphalt mixture type index of retained strength (%) 85 80 71 94 87 76 ورقة1 hydrated lime filler portland cement filler soft sandstone filler d47 7230 5100 4618 d66 4492 3851 2663 ورقة1 0 0 0 0 0 0 hydrated lime filler portland cement filler soft sandstone filler recovered asphalt cement type absolute viscosity at 60 c (poises) ورقة2 hydrated lime filler portland cement filler soft sandstone filler d47 4.27 2.93 3.51 d66 2.66 1.85 2.09 ورقة2 0 0 0 0 0 0 hydrated lime filler portland cement filler soft sandstone filler recovered asphalt cement type stiffness modulus at 60 c (pa) ورقة4 d47hl 3.8 d47pc 4.3 d47ss 4.6 d66hl 3.5 d66pc 4 d66ss 4.2 ورقة4 0 0 0 0 0 0 asphalt mixture type air voids (%) ورقة3 d47hl 85 d47pc 80 d47ss 71 d66hl 94 d66pc 87 d66ss 76 ورقة3 0 0 0 0 0 0 asphalt mixture type marshall stiffness (kn/mm) تخطيط3 d47 d47 d47 d66 d66 d66 hydrated lime filler portland cement filler soft sandstone filler recovered asphalt cement type absolute viscosity at 60 (poises) 7230 5100 4618 4492 3851 2663 ورقة1 hydrated lime filler portland cement filler soft sandstone filler d47 7230 5100 4618 d66 4492 3851 2663 ورقة1 hydrated lime filler portland cement filler soft sandstone filler recovered asphalt cement type absolute viscosity at 60 (poises) ورقة2 hydrated lime filler portland cement filler soft sandstone filler d47 4.27 2.93 3.51 d66 2.66 1.85 2.09 ورقة2 hydrated lime filler portland cement filler soft sandstone filler recovered asphalt cement type stiffness modulus at 60 (pa) ورقة4 d47hl 928077 d47pc 327185 d47ss 204863 d66hl 1522986 d66pc 710485 d66ss 476114 ورقة4 asphalt mixture type number of cycle to failure ورقة5 3 5 10 30 50 100 300 500 750 1000 ورقة3 d47hl 1951 d47pc 1643 d47ss 1486 d66hl 1334 d66pc 1202 d66ss 1111 ورقة3 asphalt mixture type marshall stiffness (kn/mm) تخطيط1 d47hl d47pc d47ss d66hl d66pc d66ss asphalt mixture type indirect tensile strength (kpa) 1951 1643 1486 1334 1202 1111 ورقة1 hydrated lime filler portland cement filler soft sandstone filler d47 7230 5100 4618 d66 4492 3851 2663 ورقة1 0 0 0 0 0 0 hydrated lime filler portland cement filler soft sandstone filler recovered asphalt cement type absolute viscosity at 60 c (poises) ورقة2 hydrated lime filler portland cement filler soft sandstone filler d47 4.27 2.93 3.51 d66 2.66 1.85 2.09 ورقة2 0 0 0 0 0 0 hydrated lime filler portland cement filler soft sandstone filler recovered asphalt cement type stiffness modulus at 60 c (pa) ورقة4 d47hl 3.8 d47pc 4.3 d47ss 4.6 d66hl 3.5 d66pc 4 d66ss 4.2 ورقة4 0 0 0 0 0 0 asphalt mixture type air voids (%) ورقة3 d47hl 1951 d47pc 1643 d47ss 1486 d66hl 1334 d66pc 1202 d66ss 1111 ورقة3 0 0 0 0 0 0 asphalt mixture type marshall stiffness (kn/mm) al-hikama intermediate school mohammed abbas al-khwarizmi engineering journal, vol.4 , no. 1 pp 6879 (2008) al-khwarizmi engineering journal al-khwarizmi engineering journal, vol.4 , no.1 , pp 68-79 (2008 ) evaluation of hydrated lime filler in asphalt mixtures dr. mohammed abbas hasan al-jumaily engineering college university of kufa (received 16 february 2007 ; accepted 26 november 2007) abstract mineral filler is one of important materials and affecting on properties and quality of asphalt mixtures .there are different types of mineral filler depended on cost and quality , the matter encourages us to achieve this study to evaluate hydrated lime filler effects on properties of asphalt mixes related with strength and durability. conventional asphaltic concrete mixtures with portland cement and soft sandstone fillers and mixtures modified with hydrated lime were evaluated for their fundamental engineering properties as defined by marshall properties , index of retained strength , indirect tensile strength , permanent deformation characteristics , and fatigue resistance .a typical dense graded mixture employed in construction of surface course pavement in iraq in accordance with scrb specifications was used .the materials used in this study included mineral aggregate materials (coarse and fine sizes) were originally obtained from najaf sea quarries and two grades of asphalt cements produced from daurah refinery which are d47 and d66 . the physical properties , stiffness modulus and chemical composition are evaluated for the recovered asphalt cement from prepared asphalt mixes containing various filler types .the paper results indicated that the addition of hydrated lime as mineral filler improved the permanent deformation characteristics and fatigue life and the use of hydrated lime will decrease the moisture susceptibility of the asphalt mixtures. key word: hydrated lime, mineral filler, chemical composition, retained strength index, indirect tensile strength, indirect tensile creep, indirect tensile fatigue, rutting distress, absolute viscosity, stiffness modulus. introduction permanent deformation, fatigue and moisture damage are common distresses found in asphalt pavements today. in many cases , mineral fillers will increase the mixture stiffness. in iraq , the performance of asphalt pavements has deteriorated over the last decade . heavy axle loads coupled with the hot climate and poor drainage systems in middle part of iraq are major contributing factors to the development of severe pavement distresses such as permanent deformation and loss of structure because of moisture damage. the use of lime to reduce moisture sensitivity has been promoted by fhwa for many years (shah,1963). the structure of hydrated lime consists of different size fractions. the larger size fraction performs as a filler and increases the stiffness of the asphalt mixture. the smaller size fraction increases asphalt film thickness enhancing viscosity of the asphalt , and improving the asphalt cohesion and stiffness. adhesion between the aggregate and asphalt increases (dickinson ,1984) , resulting in decreased mixture segregation. the water sensitivity of asphalt mixes treated with hydrated lime and antistrip agents was evaluated previously (kennedy et.al.,1982 and kennedy et. al. , 1991). results from these tests depended on the actual combinations of aggregate , asphalt and additives. however, among the antistrip agents, hydrated lime was most effective in increasing the tensile strength and in improving the water sensitivity of the mixture. this paper presents the results of a comparative study conducted on various asphalt mixes with three different mineral filler types to determine if the use of hydrated lime as a mineral filler leads to any improvement in the fundamental engineering properties. in addition, effect of hydrated lime on physical properties and chemical composition of asphalt cement has been investigated in this study. materials asphalt cement the two grades of asphalt cement used in this work included: (40-50) and(60-70) penetration grade asphalt from daurah refinery .the different physical properties of asphalt cement are evaluated according to astm standards including absolute viscosity (d2171) , standard penetration (d5),ductility (d113), specific gravity (d70) , solubility in trichloroethylene (d2042) and thin-film oven test (d1754). the chemical composition of the asphalt cement is determined by the modified precipitation method of rostler (astm d 4124 ) , in which the asphalt is separated into four fractions (rostler and rostler ,1981) as shown in table 1. the physical properties and chemical composition of the two asphalt types (d47 and d66) as well as state commission of roads and bridges , scrb (scrb, 2003)specifications are presented in table 2 . aggregate and mineral filler properties mineral aggregate materials (coarse and fine sizes) were originally obtained from najaf sea quarries. the aggregate properties are listed in table 3. three different types of mineral filler were used as mineral filler in preparation of various asphalt mixes because these types were available in a large quantity during study period. the hydrated lime filler was obtained from karbala’a factory. the portland cement filler was brought from kufa cement factory . the soft sandstone powder filler was obtained from najaf sea quarries. the physical properties of the mineral filler types are shown in table 4. asphalt concrete mixtures the asphalt concrete mixtures are prepared using crushed gravel and sand with three different mineral fillers and two asphalt cement types . the mid limits of the 12.5 mm nominal maximum size dense gradation in accordance with scrb (scrb, 2003) specification requirements are used in preparing six asphalt mixtures ( two asphalt cements and three mineral fillers) as reported in table 5. the six asphalt mixture types included in this study are coded as shown in table 6 . the optimum asphalt contents (o.a.c) of various asphalt mixtures which were determined from standard marshall mix design in accordance with astm d1559 (astm,2003) are reported in table 7 . also, marshall properties at (o.a.c) and scrb (scrb ,2003) specifications for asphalt mixes used in the construction of surface course are presented in table 7. fundamental test procedure four fundamental tests were conducted to characterize the six mixtures and determining the effects of the hydrated lime mineral filler on the properties of asphalt mixes. three specimens were prepared and the average results are reported for all tests .a brief description of each test is given below: index of retained strength test index of retained strength test is used to evaluate moisture damage of asphalt pavement in accordance with method astm d1075 (astm ,2003). it is one of tests required by scrb (scrb , 2003) specifications to be performed on asphalt mixes used in surface course in addition to marshall tests. this test is intended to measure the loss of cohesion resulting from the action of water on compacted bituminous mixtures containing penetration grade asphalt. a set of six cylindrical specimens 4 in (101.6mm) in diameter by 4 in (101.6mm) in height was prepared for each asphalt mixtures in according with the procedure described in the standard method of test for compressive strength of bituminous mixtures of astm d1074 (astm ,2003). indirect tensile strength test the indirect tensile strength at 25oc is evaluated for cylindrical specimens (101.6mm diameter × 63.5 mm height ) in accordance with astm d4123 (astm,2003). indirect tensile creep test at testing temperature of 40 oc , a compressive stress of 0.138 mpa (20 psi) was applied on the marshall specimen (101.6mm diameter × 63.5 mm height ). the loading times include (3,5,10,100, and 1000 seconds) and rest periods are (2,2,2,4,and 8 minutes). the total permanent strains, εp (in/in) at the end of each rest period were measured. in last loading time (1000 seconds), the creep deformations were measured after 3, 6, 10, 30, 60,100, 300, 600, and 1000 seconds durations. the creep compliance, c (t), at each of these loading durations is calculated as follows: c(t)=є(t)/σo … (1) where: c(t)= creep compliance at (1/mpa), є(t)=vertical strain at loading duration t (mm/mm), and σo = applied stress (mpa) . indirect tensile fatigue test to determine the fatigue resistance of the asphalt concrete samples, this test was conducted at 25oc temperature by using the machine manufactured by the researcher in the highway laboratory in college of engineering in kufa university . the (10 %) of the test failure load obtained from indirect tensile test was used as the peak value of the cyclic load with loading duration of 0.10 second followed by a rest period of 0.90 second was applied to the test specimen (loulizi et.al.,2002) .the number of cycles were monitored through the duration of test and the test was terminated when the specimen reached to failure. 4. discussion of test results the test results obtained from experimental work will be discussed in the following sections effect of mineral filler type on asphalt cement properties and chemical composition to evaluate the effect of mineral filler type on the physical properties and chemical composition of asphalt cement , there is need to recovery the asphalt from asphalt mixture specimens .extraction test was achieved by using a solvent in accordance with the method standardized in astm d 2172 (astm , 2003) to quantitative separation of the aggregate and asphalt cement . the asphalt was then recovered from asphalt-solvent solution (extract) in accordance with the method described in astm d1856 (astm ,2003). the stiffness modulus values of recovered asphalt cement types at temperature of 60 oc and a loading time of 0.02 second were determined by using shell nomographs (bonnaure et. al. ,1977) .three properties of the recovered asphalt cement are evaluated : absolute viscosity , ductility and stiffness modulus .the effect of mineral filler type on these properties are shown in fig.1. (a) absolute viscosity (b) ductility (c) stiffness modulus fig. (1) effect of mineral filler type on asphalt cement properties it can be noticed that recovered asphalt cement from mixes containing hydrated lime as a filler exhibits high absolute viscosity and stiffness values and has low tensile properties represented by low ductility values when compared with other asphalt types. the chemical composition parameter, gaestel index (ig) defined as the ratio of (asphaltenes and saturates ) fractions to (naphthene aromatics and polar aromatics) fractions which is related with asphalt durability (ishai i. ,1995). high values of (ig) refers to reduction in the asphalt durability and asphalt exhibits brittle and hardening behavior. the chemical fractions and gaestel index values of original and recovered asphalt cement types are reported in table 8. the asphalt cement considers durable if the range of (ig) values lie within a range of about (0.4-1.2) (ishai i. ,1995). it may be seen from table 8 that all asphalt cement types fall within this range and have good durability. effect of mineral filler type on marshall stiffness and air voids marshall stiffness (kn/mm) , which is calculated as the ratio between marshall stability and corresponding marshall flow at optimum asphalt content, represents the combination of stability and flow in single value .marshall stiffness gives the indication about the resistance of asphalt mixture to plastic flow resulted from loading. high values of marshall stiffness means the asphalt mixtures have considerable resistance to permanent deformation in case these mixes will be used in construction of pavement. it is well known that percentage of air voids is related to durability of asphalt mixture. the role of mineral filler type in increasing or decreasing of air voids is necessary to be investigation. the effect of mineral filler type on marshall stiffness and air voids is shown in fig. 2. (a) marshall stiffness (b) air voids fig.(2) effect of mineral filler type on marshall stiffness and air voids of asphalt mixes it can be seen from figure that using hydrated lime as a mineral filler increases the mixture stiffness and improving the it durability represented by low air voids percent in comparison with using other mineral filler types. effect of mineral filler type on index of retained strength the moisture damage of asphalt concrete mixtures had produced serious distress , reduced performance and increased maintenance for asphalt pavements. scrb (scrb ,2003) specifications require this distress to be checked by performing the index of retained strength percent test . fig. 3 indicates effect of mineral filler type on index of retained strength percent of asphalt mixes fig. (3) effect of mineral filler type on index of retained strength percent of asphalt mixes scrb (scrb, 2003) specifications require the minimum percentage of index of retained strength as 70 % for asphalt mixtures used in a construction of surface course pavement . it can be noticed from fig. 3 that all asphalt mixtures have index of retained strength percent above minimum percentage from test results illustrated in figure , it can be seen that asphalt mixtures prepared from hydrated lime filler has high resistance to moisture damage because they exhibit high percentages of index of retained strength in comparison with other asphalt mixtures. effect of mineral filler type on indirect tensile strength (its) fig. 4 presents the indirect tensile strength (its) test results. in this test , high tensile strength at failure is desirable property for stiff mixtures. for the its test performed at 25oc , the addition of hydrated lime increases the strength for d47hl and d66hl asphalt mixtures. this may be due to the fact that at intermediate temperatures the combined viscosity of the asphalt and minus 0.075 material decreases more in mixtures with other mineral filler types , causing the mixture to lose more of its strength. in other words , the using of the lime filler improved the indirect tensile strength for two asphalt mixtures. fig. (4) effect of mineral filler type on indirect tensile strength of asphalt mixes effect of mineral filler type on rutting distress one of the main types of structural distress which may affect the performance of asphalt concrete pavements is permanent deformation , also known as rutting . rutting develops with an increasing number of axle load applications. rutting is caused by a combination of densification and shear related deformation and may occur in any course of a pavement structure. vesys 5w software program is short for visco elastic pavement system analysis program (kenis et. al. ,1982) and (fhwa , 2003) . it is necessary to mention that the rut depth computed by the vesys 5w program is the summation of the permanent deformation values of all courses .therefore , the vesys 5w software program requires the input of material properties of the courses ,the course thicknesses ,traffic data ,and environmental conditions. these input data will be described in the following articles: material properties to obtain input parameters required for the vesys 5w software , an average curve of creep compliance c (t) versus time is constructed on a log-log graph and extrapolated backward to obtain values of c (t) at 0.1 and 0.30 seconds . the total permanent strain versus incremental time of loading is plotted on a log-log graph and the best-fit line is obtained .the intersection of the line with the vertical axis is denoted by i and the slope by s . the permanent deformation properties μ and α are determined as follows: μ=is/ε … ( 2 ) α=1-s … ( 3 ) where ε is the recovered strain which was obtained from resilient modulus test the parameters (α and μ) obtained from the incremental static creep test performed on asphalt mixture are used as input into the vesys 5w software to estimate the rut depth of a specific pavement structure using properties of different asphalt mixtures. resilient modulus values, alpha (α) and gnu (µ) parameters for binder, base, subbase and subgrade courses are taken as a default values [fujie and tom (2002)] and [mohammed and michael (1999)] while corresponding values for the surface course were determined from laboratory tests. average resilient modulus values (mpa) of various asphalt mixtures which were obtained by conducting the resilient modulus test on three marshall specimens for different asphalt mixes. the specimens were tested at 25, 40 and 60 oc temperatures according to a modified astm d4123 (astm,2003). the conventional flexible pavement structures are layered systems , and consist of a surface course , binder course , base course ,subbase course and subgrade . the selected pavement structure consists of five courses with material properties and thicknesses are reported in table 9. the variability coefficients of the course properties were taken as 10, 10, 15, 15 and 20 % for the surface, binder, base, subbase and subgrade courses respectively. traffic loading initially an equivalent 80 kn (18 kip) single axle load (esal) with dual tires was adopted . traffic loading is assumed to be one million esal at end of first year of pavement service life . the dual tires are spaced 13.57 inch (34.5 cm) apart with tire pressure of 80 psi (552 kpa) and radius contact area of 4.25 inch (10.8 cm).tire contact area depends on contact pressure .thus , the contact pressure was assumed equal to the tire pressure (no effect of tire wall ) . the use of esal is based on the results of experiments that have been shown that the effect of any load on the performance of a pavement can be represented in terms of the number of single applications of (esal). annual growth rate is assumed to be 10 percent. environmental conditions many environmental conditions influence the performance of the flexible pavement. the only environmental effect that is included in the developed model is the temperature of the asphalt course. changes in the temperature of the asphalt course affect the elastic and viscous properties of the asphalt. three temperatures (25 ,40 and 60 oc) were used in estimation of rut depth within selected pavement structure. rut depth values the system rutting formulation treats the pavement system as a whole and first calculates an equivalent set of pavement system permanent deformation parameters (α sys and μ sys) which are determined as functions of load repetitions by least square regression analysis .vesys 5w software program is applied to estimate rut depth in selected pavement structure by using resilient modulus values , three testing temperatures . fig. 5 below presents the rut depth values of various asphalt mixtures at end of 10 years of analysis time. fig. (5) effect of mineral filler type on rut depth values of asphalt mixes when comparing the rut depth results showed in fig. 5 , it is noted that the addition of hydrated lime improved the performance indicators with low rut depth values . effect of mineral filler type on indirect tensile fatigue test results fatigue cracks are caused by repeated traffic loading and it occurs in asphalt pavements when repeated stress or strain having a maximum value generally less than the ultimate strength of the material (yoder and witczak ,1975) . the results of the indirect tensile fatigue test are presented in fig. 6 . while evaluating the fatigue resistance of asphalt concrete mixes , the number of cycles to failure are used as performance indicators.a high number of cycles to failure are the desired properties. fig. 6: effect of mineral filler type on number of cycle to failure of asphalt mixes the results of the fatigue test indicate that the addition of hydrated lime as a filler increased the fatigue resistance of the mixes. the d66hl mixture was the mix that showed the highest endurance to the repeated cyclic loading of the fatigue test. 5. conclusions within the limitations of materials and test procedures used in this work, the following are concluded: 1. the smaller size fractions of hydrated lime enhancing the absolute viscosity , and improving the asphalt durability and stiffness of the recovered asphalt from asphalt concrete mixture containing hydrated lime as a filler. 2. the hydrated lime is effective in increasing the moisture damage resistance of the mixture, thereby providing pavements that are highly strip resistance. 3. the asphalt mixes with hydrated lime showed improved stiffening and durability properties when incorporated into the mixture. 4. the tensile strength are highest for the asphalt concrete mixes containing hydrated lime fillers than mixes designed with other mineral filler types. 5. the research results revealed that the hydrated lime fillers can have an effect on the rutting susceptibility and fatigue life of flexible pavements , and the use of hydrated lime can improve resistance of the mixes to rutting and fatigue cracking distresses. table 1: chemical composition of asphalt cement fraction chemical reactivity asphaltenes – a low polar aromatics –pa high napthene aromatics -na high saturates -s low table 2 : the physical properties chemical composition of asphalt cement types property daurah (40-50) daurah (60-70) scrb specifications (40-50) (60-70) standard penetration ,1/10 mm 47 66 40-50 60-70 absolute viscosity at 60 oc, poises 2033 1340 ----- ------- ductility ( 25 oc , 5 cm/min ),cm >100 >100 =>100 =>100 specific gravity at 25oc 1.035 1.03 ------ ------- solubility in trichloroethylene ,% 99.72 99.9 >99 >99 mass loss , % 0.35 0.58 <0.75 <0.80 residue from thin film oven test -retained penetration,% of original -ductility ( 25 oc,5 cm /min.), cm 65 75 61 92 >55 >25 >52 >50 chemical composition , % asphaltenes – a 20.03 18.31 polar aromatics –pa 35.42 37.08 napthene aromatics -na 24.20 25.37 saturates -s 20.35 19.24 table 3 : coarse and fine aggregate properties property value test method specification source specification requirements coarse aggregate sieve size (mm) 12.5 to 2.36 scrb ------------ bulk specific gravity 2.632 astm c127 -------- ------------- percent wear, los angeles (%) 19.2 astm c535 scrb not more than 30 % % crushed pieces (one face) 96 --------- scrb at least 90% by weight of material soundness, total weight loss percent 3 astm c88 scrb not more than 12 % fine aggregate sieve size (mm) 2.36 to 0.075 scrb -------- bulk specific gravity 2.676 astm c128 ------ ------- soundness , total weight loss percent 4.6 astm c88 scrb not more than 12 % table 4: physical properties of mineral filler types property test method result hydrated lime passing sieve no. 200, % -------------- 100 specific gravity astm c128 2.785 plasticity index aashto t90 1.5 portland cement passing sieve no. 200, % -------------- 96 specific gravity astm c128 3.15 surface area (m2/kg) 357.82 soft sandstone specific gravity astm c128 2.653 plasticity index aashto t90 3.2 table 5: selected gradation of aggregate sieve size (mm) 19 12.5 9.5 4.75 2.36 0.30 0.075 % passing 100 95 83 59 43 13 7 table 6: the code for the six asphalt mixture types asphalt mixture code description d47hl daurah 47 pen.asphalt with hydrated lime filler d47pc daurah 47 pen.asphalt with portland cement filler d47ss daurah 47 pen.asphalt with soft sandstone filler d66hl daurah 66 pen.asphalt with hydrated lime filler d66pc daurah 66 pen.asphalt with portland cement filler d66ss daurah 66 pen.asphalt with soft sandstone filler table 7 : marshall properties of different asphalt mixture types at optimum asphalt content scrb specifications asphalt mixture type property d66ss d66pc d66hl d47ss d47pc d47hl min. 8 kn 9.5 8.6 10.7 12.9 11.3 14.4 marshall stability (kn) 2-4 mm 3.4 3.7 3.1 3.2 3.6 2.8 marshall flow(mm) 3-5 % 4.2 4.0 3.5 4.6 4.3 3.8 voids in total mix (%) min. 14 15.9 15.1 14.8 16.9 16.6 15.7 voids in mineral aggregate (%) 65-85 % 73.6 73.5 76.4 72.8 74.1 75.8 voids filled with asphalt (%) 4-6 % 5.48 4.7 5.20 5.03 4.9 5.36 optimum asphalt content (%) table 8: chemical fractions and gaestel index values of original and recovered asphalt cement types asphalt cement original d47 original d66 recovered asphalt cement types d47hl d47pc d47ss d66hl d66pc d66ss % a 20.03 18.31 26.29 23.77 22.61 23.24 21.48 20.07 % p.a. 35.42 37.08 22.45 33.65 22.92 20.19 38.56 36.41 % n.a. 24.20 25.37 31.80 22.61 34.44 38.35 21.59 24.83 % s 20.35 19.24 19.46 19.97 20.03 18.22 18.37 18.69 ig 0.68 0.60 0.84 0.78 0.74 0.71 0.66 0.63 table 9: material properties of pavement structure courses material properties surface binder base subbase subgrade resilient modulus (psi) variable 143000 66000 10000 5000 poisson’s ratio 0.35 0.35 0.35 0.40 0.45 thickness (cm) 5 8 15 25 infinity permanent deformation properties alpha (α) variable 0.66 0.65 0.88 0.77 gnu (µ) variable 0.12 0.15 0.03 0.04 references 1. aashto,(1989),"standard specification for transportation materials and methods of sampling and testing ", american association of state highway and transportation officials, 14th edition, part i, part ii,washington, d.c., u.s.a 2. astm standards, (2003), "roads and paving materials" , annual book of the american society for testing and materials standards , section 4 ,vol. 04-03. 3. bonnaure , f., g. gest , a. gravots , and p. uge , (1977), " a new method of predicting the stiffness of asphalt paving mixtures ", proceeding of association of asphalt paving technologists , vol.46 , pp.64 – 100. 4. fhwa , (2003) ,"vesys 5w ’s user manual ", federal highway administration office (fhwa)of infrastructure research and development ,truck pavement interaction program, june 26, washington, d.c. 5. fujie ,z. and tom, s.,(2002)," vesys 5 rutting model calibrations with local accelerated pavement test data and associated implementation " , texas department of transportation in cooperation with the u.s. department of transportation federal highway administration , september, report 9-1502-01-2 , project number 9-1502. 6. ishai i. ,(1995), "long term laboratory and field behavior of ppa asphalt cement blends ", proceedings of the association of asphalt paving technologists, vol. 64, pp.306-337. 7. kenis, w.j., j.a. sherwood, and t.f. mcmahon,(1982), "verification and application of the vesys structural subsystem", proceedings of the fifth international conference on the structural design of asphalt pavements, the netherlands, 1982 , vol.1, pp. 333-346. 8. kennedy , thomas w., roberts, freddy l., and lee , kang w., (1982), " evaluation of moisture susceptibility of asphalt mixtures using the texas freeze-thaw pedestal test" ,proceeding of association of asphalt paving technologists , vol.51 , pp.327 – 341. 9. kennedy , thomas w. , and ping , w. virgil , (1991), " an evaluation of effectiveness of antistripping additives in protecting asphalt mixtures from moisture damage " , annual meeting of the association of asphalt paving technologists , march 4-6 . 10. loulizi, a., al-qadi, i.l., lahour, s., and freeman, t.e., (2002), "measurement of vertical compressive stress pulse in flexible pavements and its representation for dynamic loading", transportation research board, paper no.02-2376. 11. mohammed , m. e. and michael , s.m.,(1999), " effect of aggregate gradation on the rutting potential of superpave mixes " , transportation research board , 78th annual meeting , january 10-14 , washington , d.c. 12. rostler and rostler , k.,(1981), "basic considerations in asphalt research pertaining to durability ", proceeding of association of asphalt paving technologists , vol.50. 13. shah ,s.c., (1963) , " asphaltic concrete pavement survey " , louisiana transportation research center report no.9 , baton rouge , louisiana , 1963. 14. state commission of roads and bridges (scrb), (2003), "general specification for roads and bridges", republic of iraq, ministry of housing and construction, department of planning and studies, baghdad, revised edition ,addendum no.3. 15. yoder , e . j. and witczak , m. w. , (1975) , " principles of pavement design " , second edition , john wiley and sons , new york. تقييم الجير المطفأ كمادة مالئة في الخلطات الاسفلتية د. محمد عباس حسن الجميلي قسم الهندسة المدنية كلية الهندسة جامعة الكوفة الخـــلاصــة: المادة المالئة المعدنية هي احد المواد المهمة والمؤثرة على خواص ونوعية الخلطات الإسفلتية, وتوجد هناك أنواع مختلفة من المواد المالئة متباينة فيما بينها من ناحية الكلفة والنوعية، الامر الذي شجع على إجراء هذه الدراسة لتقييم تأثيرات الجير المطفأ على خواص الخلطات الإسفلتية من حيث مقاومة الأحمال و متانة . تم تحضير الخلطات الإسفلتية التقليدية باستخدام اسمنت بورتلاند و حجر رملي مطحون كمادة المالئة و أخرى معدلة الجير المطفأ لتقيم خواصها الهندسية الأساسيةِ كما هي مُعَرَّفة من قبل خواص مارشال، دليل المقاومة المسترجعة، مقاومة الشدّ الغير مباشر، خصائص التشوه دائمي، ومقاومة الكلل.تم استخدام التدرج الكثيف المثالي لتحضير الخلطة و المستخدم في انشاء الطبقة السطحية في العراق بموجب مواصفات(scrb) . المواد ألمستعملة في هذه الدراسة تضمنت مواد ركام معدنية (مقاسات خشنة وناعمة) تم الحصول عليها من مقالع بحر نجف و نوعان من الإسفلت المنتج من مصفى الدورة وهما d66, d47. تم تقييم الخواص الفيزيائية ومعامل الصلادة و التركيب الكيمياوي للإسفلت المستعادة من الخلطات الإسفلتية المحضرة و التي تحتوي على المواد المالئة المختلفة . أظهرت نتائج البحث بأنّ إضافةَ الجير المطفأ كمادة مالئة حَسّنَ خصائص التشوهِ الدائمي وعمر الكلل وكذلك استعمال الجير المطفأ يقلل من حساسية الرطوبة للخلطات الإسفلتية. � embed excel.chart.8 \s ��� � embed excel.chart.8 \s ��� � embed excel.chart.8 \s ��� oc � embed excel.chart.8 \s ��� oc x105 oc×10 5 � embed pbrush ��� page 77 _1258123747.xls _1300184780.xls _1039819024.xls _1258123537.xls _1173207870 _1039817889.xls microsoft word (38-50) hyder f. neamah al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 5, no. 3, pp 38 50 (2009) stress analysis of guide rails of elevators hayder al-shuka* wisam ِal-wajidi** * department of mechanical engineering/ college of engineering/university of baghdad email:haider_neama@yahoo.com * department of mechanical engineering/ college of engineering/al-moustenseria university (received 16 january 2008; accepted 28 july 2009) abstract the mechanical design of elevator elements is always performed by international standards. the engineer selects the appropriate elements of elevator according to catalogues without knowing scientific details. therefore, a theoretical analysis is achieved at two operating conditions for guide rails (1) safety gear operation, and (2) running condition with the loads unevenly distributed on the elevator car. the guide rail is considered a continuous beam with variable supports. then the british code is listed showing the equations used in it. the theoretical equations showed that guide rails are never subjected to stress in simultaneous combined buckling and bending in the plane, where the bending moment is exerted. it is always a combination of pressure and bending. consequently, it is wrong to consider a simultaneous effect of buckling and bending. the equations in the catalogues oppose the theoretical results concerning buckling of guide rails. therefore, a recommended calculation method for guide rails is presented to be an acceptable method for analysis of guide rail. keywords: guide rail, stress, deflection, safety gear, buckling, continuous beam, standard codes. 1. introduction the functions of guide rails are as follows: (1) to guide the car and the counterweight in their vertical travel and to minimize their horizontal movement, (2) to prevent tilting of the car due to eccentric load, and (3) to stop and hold the car on the application of the safety gear. fig.1 shows the components of the elevator and the cross-section of the guide-rail [1]. both the car and the counterweight must be guided by at least two rigid steel guide rails, which are manufactured from a structural steel having a tensile strength of no less than 370 mpa and not greater than 520 mpa [2]. in the u.s., a suitable nonmetallic material may be used for guide rails where steel may present an accident hazard, as in chemical and explosive plants, provided the rated speed of the car does not exceed 0.76 m/s. in recent years, round guide rails have been successfully used for hydraulic elevators and counterweights without safety gears [3]. through investigating the studies on the elevator components, the calculations of guide rails depend mainly upon usa or european codes. utsunomiya et. al. [4] invented a guide device for an elevator in which a pair of corresponding actuators were controlled in accordance with information from acceleration sensors, and the force with which guide members were pressed against guide rails was adjusted. fig. 1. components of elevators hayder f. neamah al-khwarizmi engineering journal, vol. 5, no. 3, pp 38 -50 (2009) 39 recep et. al.[5] performed the calculation and selection of guide rails according to international standard and compared the results with fea. penn et. al. [6] uses ansys to improve the manufacturing and design of a neoprene elevator roller guide. the study uses 2d and 3d hyperelastic and contact elements to model neoprene material tests and also highly deformed roller guide proof tests. the ansys analysis succeeded in modeling the neoprene material performance. geometry changes in the shape of the neoprene were studied to reduce adhesion stresses between the neoprene and aluminum center hub, and yet to maintain the spring stiffness of the current roller guide design. clem skalski and barker mohandas [7] performed a procedure to control the vibration of the guide rail. zhu et. al. [8] analyzed the vibration of elevators depending on the present theory of dynamic analysis of elevator systems. the vibration models of elevator systems in the horizontal and vertical direction are established. the seismic responses of the building are used as excitation and input into the model. differential equations of the system are set up and the timehistory of the dynamic responses of the main parts are worked out. finally, some earthquake protective measures for elevators are proposed. the current study proved that there are problems with the used codes, and a preferred method was invented quoting from the theoretical and international standard to calculate and select the best guide rails. 2. guide rails calculations in the calculation of the guide rails, two operating conditions should be taken into consideration (1) safety gear operation, (2) running conditions with the load unevenly distributed on the car floor. in most national standards, the calculation of stress in guide rails is carried out for (2), while the calculation of deflection concerns quite different operating conditions, namely(1) [8]. three stages of calculations are performed in the current paper: 1) theoretical analysis, 2) the british codes, and 3) an acceptable method for design of guide rails is introduced after completing the previous two stages. 2.1. theoretical analysis 2.1.1. during safety gear operation (without taking buckling into consideration) the aim of the theoretical analysis is to find the nature of relation between buckling and bending moments during safety gear operation. the following will be studied:  the bending moment distribution without the effect of buckling and the guide rail is considered as a continuous beam.  the effect of buckling is considered with the bending moment at the section of guide rail that is subjected to compression force. in the first stage, the guide rails will be analyzed by calculating the maximum bending moment produced by the braking force without taking buckling into consideration. we will assume a simultaneous effect of buckling and bending moments in the second stage. the guide rails will be considered a continuous beam with a variable number of supports. the theorem of three moments and the finite element method may be used as methods of solution. the first method is used for the derivation of the related equations. the guide rail is subjected to a combined effect of the braking fb, acting parallel to the longitudinal axis of the guide rail, and the outer moment fb×e. the outer moment is induced due to the eccentric position of the braking force fb, which is represented by the distance e, as shown in fig. 2. the bending moment m (z) depends on the number of beam fields and on the outer moment fb×e(both value and location). fig. 2. location of the braking force fb equations for the maximum bending moment m(z) as a function of z, and values and locations of the extremes of individual functions are reviewed in table 1 for fb×e acting in field i of hayder f. neamah al-khwarizmi engineering journal, vol. 5, no. 3, pp 38 -50 (2009) 40 the beam and in table 2 for fb×e acting in field ii. the maximum bending moment always occurs at the point of application of the outer moment fb×e. we will derive only two equations which are listed in the mentioned tables. a) assumptions i. efb  in field i(span i). ii. no. of fields is two, as shown in fig 3. fig. 3. the location of the braking force at field i by using theorem of three moments [6]**, ei l h l h l ba l aa lmllmlm 6*) 2 3 1 1( 2 226 1 116 23)21(2211   … (1) where h1, h3 are the deflections at supports 1 and 3 respectively. there are no moments at the edge supports, 031  mm , l1=l2=l ... (1a) )3( 6 22 1 11 lz l ef l aa b  … (1b) 0 6 2 22  l ba … (1c) by substituting eqns.(1a,1b and 1c) into eqn.(1), it results in: )3()(2 22 2 lz l ef llm b  … (1d) )3( 4 22 22 lz l ef m b  ... (1e) by taking moments about support (2),  0)3( 4 )( 22 21 eflz l ef lr b b )53( 4 )43( 4 )( 1 22 2 222 2 lz l ef llz l ef lr bb  )53( 4 22 21 lz l efbr  …(1f) zrzm 1)(  … (1j) to find the maximum moment that produces through the guide rail, lz zl l ef dz zdm b 7454.0 )95( 4 0 )( 22 3   … (1i) by substituting eqn.(1i) into eqn.(1j) to find the maximum bending moment, it results in: efzm b6211.0)( max  ... (2) this value is listed in table 1. b) assumption i. efb  in field ii(span ii). ii. no. of fields is two. iii. z will be taken from the left support of field ii, as shown in fig. 4. the equations are the same as (case a), by replacing z with (l-z), therefore, from eqn.(1j), ))(35( 4 )( 22 3 zll l ef zm b  (l-z) )2493( 4 )( 3223 3 lzllzz l ef zm b  … (3) this value is listed in table 2. fig. 4. the location of the braking force at fieldii 1l 2l 1l 2l z hayder f. neamah al-khwarizmi engineering journal, vol. 5, no. 3, pp 38 -50 (2009) 41 table 1, bending moment m(z) and its maximum values mmax ( efb  in field i) (spani) number of fields (spans) m(z) maximum value m(z)max location of the extreme zm equation no. 2 )35( 4 32 3 zzl l efb   efb 6211.0 0.7454 l 1&2 3 )1219( 15 32 3 zzl l efb   efb 6135.0 0.7265 l 4 )4571( 56 32 3 zzl l efb   efb 6130.0 0.7252 l 5 )168265( 209 32 3 zzl l efb   efb 6129.0 0.7251 l table 2, bending moment m(z) and its maximum values mmax ( efb  in field ii) (span ii) number of fields m(z) maximum value m(z)max location of the extreme zm equation no. 2 )3942( 4 3223 3 zzlzll l efb    efb  6210.0 0.2546 l 3 3 )3045147( 15 3223 3 zzlzll l efb    ef ef b b   6161.0 6161.0 0.1927 l 0.8073 l 4 )1171715226( 56 3223 3 zzlzll l efb    ef ef b b   6060.0 6162.0 0.1885 l 0.7858 l 5 )43869319497( 209 3223 3 zzlzll l efb    ef ef b b   6057.0 6162.0 0.1882 l 0.7844 l 2.1.2. during safety gear operation (taking buckling into consideration) safety gear location is of prime significance. when the safety gear is located under the car floor, the gripping of the gide rails may take place in field i. if the safety gear is mounted above the car roof the guide rails may be gripped in field ii only, as shown in fig.5. the calculation will be carried out in case of the combined bending and buckling (simultaneous bending and buckling). (a) field i fig. 5. shows the guide rail (as a beam) with the braking force. the derivation of the equation of the bending moment at any point on the left side of fb×e is listed below, from the fundamentals of statics, l mef r b 1 1   ... (4a) yfz l mef zm b b    )( )( 2 ... (4b) z eil mef y dz yd z l mef yfzm dz yd ei b b b )( )( )( 22 2 2 2 2 2      … (4c1) hayder f. neamah al-khwarizmi engineering journal, vol. 5, no. 3, pp 38 -50 (2009) 42 1l 2l 1l 2l fig. 5. f.b.d. of guide rail (at field i) the solution of this non-homogeneous second order d.e. has a combined particular and homogeneous solution shown as follows: ph yyy  , where yh and yp are the homogeneous and particular solutions respectively. for homogeneous solution, zczcy y dz yd h   sincos 0 21 2 2 2   while for particular solution, we will assume yp=az+b 0'''  yay … (4c2) by substituting eqn. (4c2) into eqn.( 4c1), it results in: z eil mef baz b )( )(0 22   , where ei fb2 by comparing the factors of z , it results in, lf mf a b b )( 2  z lf mf y b b p )( 2  lf z mfzczcy b b )(sincos 221   …(4cc) the boundary conditions from fig.5, at 00,0 1  cyz …(4d)    lf mef cyz b b sin )( 0, 2 2   … (4e) substituting eqns.(4d&4e) into eqn.(4cc), it results in,          l z l z f efm y b b    sin sin)( 2 … (4f) substituting eqn.(4f) into eqn.(4b), it results in,             l z l z f efm fz l mef zm b b b b    sin sin *)( )( )( 22 z l mef zm b   sin sin )( 2    … (5) the extreme is located at zm= π /2α and its value is given by the following formula       sin )( 2 l mef zm b ... (6) the extreme moment is located at   2mz and its value is given by the following formula      sin )( 2 l mef zm b … (6a) the graphical illustration of m(z)will be shown in the results. (b) field ii the formulae are obtained from the same initial equations by means of the same mathematical methods which are more complicated than those in field i. fig. 6 shows this case; the moment at any section through the beam(guide rail), fig. 6. f.b.d. of guide rail (at field ii) 1l 2l 1l 2l hayder f. neamah al-khwarizmi engineering journal, vol. 5, no. 3, pp 38 -50 (2009) 43 yfmzrm b 22 ... (7) m ei m f dz yd f dz md dz dy fr dz dm bb b 2 2 2 2 2 2   02 2 2  m dz md  … (8) and the solution of this d.e., zczcm  cossin 21  … (9) the boundary conditions, at z=0, m=m2 c2=m2 …(10) at  22 refmmz b          l mefm efmm b b 23 2       sin cos23 2 l llmmef c b   … (11) m3 is moment at the right support of field ii (support 3). the location of the extreme is 1 21tan 1 c c zm   ... (12) constants of integration c1 and c2 are dependent upon the moments at supports, i.e., on the location of the moment efb  . consequently, in contrast to field i, the location of the maximum bending moment )z( m is a function of the location of efb  )( in this case. the maximum value of the bending moment,        sin sin )cos( sin sin )( cos 2 3 2max         l llm z l mef zmmm m b … (13) efb  is applied at the right support (2) of field ii. this case is decisive when the safety gear is mounted above the car roof. 2.1.3. during normal operation under normal operating conditions, the load may be unevenly distributed in two perpendicular directions. in fig.7, a pictorial diagram of guide rails and all forces exerted upon them due to uneven car loading are shown. forces yf are exerted in the plane of guide rails ( )yy  , in which 1fx and 2fx are acting in xx  planes at right angles to the yy  plane. each guide rail is subjected to bending due to fy and combined bending and torsion. by taking moments about the axes x,y and z respectively, as shown in fig. 7. h egq f y y   ... (14) bh ebegq f yx x    2 2( ) 1 ... (15) bh ebegq f yx x    2 2( ) 1 ... (16) where q is rated load(kg), g is standard acceleration of free fall (m/s2), ey and ex are eccentricity of the load in the car(mm), b is width of the car (mm), c is depth of the car (mm), h is vertical distance between the centerlines of car guide shoe(mm). fig. 7. forces on guide rails during normal operation z hayder f. neamah al-khwarizmi engineering journal, vol. 5, no. 3, pp 38 -50 (2009) 44 2.2. code calculations (british standard bs 5655: part 9) [9] the stress in guide rail during the safety gear operation  is given by the equation,                     1 2 cos 2 1 x bk x bb ie fl z ef a f … (17) we should note that the second term of the above equation is combined of bending and buckling moment,i.e., there is a silmultaneous effect of buckling and bending moments. the guide rail deflection during the safety gear is limited to a maximum of 0.25  length of the machine face of the guide rail in order to avoid the risk of guide shoe disengagement from the guide rail. for this condition, the maximum permissible braking force is given by the equation,           ey e l ie f k xx b max 2 2 cos 4 … (18) in general, the braking force in the event of two guide rails being employed is given by the formula )( 2 ga kq fb    … (19) where k is the car mass, (kg). stress in guide rails calculated from eqn(17) must not exceed the values: 140 mpa for steel of 370 mpa tensile grade, 170 mpa for steel of 430 mpa tensile grade and 210 mpa for steel of 520 mpa tensile grade. the young's modulus of elasticity is specified e=2.07 (105) mpa. performance criteria based on stress and deflection in guide rails during normal operation are as follows: the guide rail is considered a simple beam with a certain degree of constraints on the fixing points and the lateral force is assumed to be imposed midway between the guide rail fixings. then the maximum stress in bending is given by x ky y z lf 6 )(  … (20) y kx x z lf 6 )(  … (21) the constant factor in denominators of the above equations would be 4 for pin-jointed supports and 8 for fixed ends. horizontal deflections at the midpoints of the beam in two perpendicular deflection are given by the formula y kx x x ky y ei lf y ei lf y 96 )( , 96 )( 33  … (22), (23) the constant factors in the above equations would be 48 for pin-jointed supports and 129 for fixed ends. the maximum permissible deflection in compliance with eqn.(21) is 3mm in the pane of guide rails (yy) and 6mm in the perpendicular directions (yx). the problems of standard codes is shown in the results. 2.3. recommended calculation method for guide rails from the theoretical analysis, it can be concluded that there is no simultaneous buckling and bending (as we will see in the results), therefore the current procedure of design of guide rails includes this note. later a case study is performed to achieve the current procedure. a. safety gear operation (1) stress in combined bending and pressure (axial stress) is [4]        x b z e c a f 1 1 …(24) bending moment is induced by the eccentrically located braking force fb; the outer moment is fb×e. the calculation is carried out for a continuous beam. coefficient c1 is given in table.3 depending upon the number of fields of continuous beam c1 is concluded from table.(1,2). the braking force for all cases is calculated from eqn.(19) . table 3, coefficient c1 number of field c1 2 0.621 3 or more 0.616 hayder f. neamah al-khwarizmi engineering journal, vol. 5, no. 3, pp 38 -50 (2009) 45 (2) stress in buckling the guide rail is assumed as a simple beam with two pinn-jointed supports, subjected to the braking force fb in its longitudinal axis. the procedure of buckling analysis is as follows [10,11,12,13,14]: a) determine the critical slenderness ratio, y dr e s   2 )  ... (25a) b) determine the slenderness ratio of the guide rail, k l sr  , a i k min ...(25b) c) if sr)d  sr ,then use euler' s equation to find the critical force at which the frame will fail if it exceed this force, 2 2 r cr s ea p   … (26) d) and if the oppose case existed, johnson' s equation is used, ]) 2 ( 1 [ 2    ry ycr s e ap  … (27) al-khwarizmi 45 al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 4, no. 4, pp 45-56 (2008) parametric study of mixed convective radiative heat transfer in an inclined annulus manal h. al-hafidh raed g. saihood departement of mechanical engineering/ university of baghdad (received 11 september 2007; accepted 11 september 2008) abstract the steady state laminar mixed convection and radiation through inclined rectangular duct with an interior circular tube is investigated numerically for a thermally and hydrodynamicaly fully developed flow. the two heat transfer mechanisms of convection and radiation are treated independently and simultaneously. the governing equations which used are continuity, momentum and energy equations. these equations are normalized and solved using the vorticitystream function and the body fitted coordinates (b.f.c) methods. the finite difference approach with the line successive over-relaxation (lsor) method is used to obtain all the computational results. the (b.f.c) method is used to generate the grid of the problem. a computer program (fortran 90) is built to calculate the steady state nusselt number (nu) for aspect ratio ar (0.55-1) and geometry ratio gr (0.1-0.9). the fluid prandtl number is 0.7, rayleigh number ra = 400, reynolds number re = 100, optical thickness (0 ≤ t ≤ 10), conductionradiation parameter (0 ≤ n ≤ 100) and inclination angle λ = 45. for the range of parameters considered, results show that radiation enhance heat transfer. it is also indicated in the results that heat transfer from the surface of the circle exceeds that of the rectangular duct. generally, nu is increased with increasing gr, t and n but it decreased with ar increase. when the radiation effect added to the heat transfer mechanism, the heat transfer rate increased. this effect increased with increasing in gr and decreasing with ar. the increasing in radiation properties lead to increase the radiation effect. tecplot 7 program was used to plot the curves which cleared these relations and isotherms and streamlines which illustrate the behavior of air through the channel and its variation with other parameters. a correlation equation is concluded to describe the radiation effect. comparison of the results with the previous work shows a good agreement. keywords: mixed convection, radiation, rectangular duct, circular tube, laminar flow. 1. introduction: various heat transfer mechanisms and geometries have been studied by some engineers and scientists purposely to augment heat transfer in heat exchangers and some other heat transfer equipments. a numerical study of natural convection in horizontal elliptic cylinder was studied by (bello-ochende, 1985) and (siegel, 1985) also analyzed the effect of buoyancy on heat transfer in a rotating tube. a perturbation analysis of combined free and forced laminar convection in a tilted elliptic cylinder was carried out by (bello-ochende and adegun, 1993). thermal radiation and laminar forced convection in the entrance region of a pipe with axial conduction and radiation were considered by (yang and ebadian, 1991) and (dong et al, 1993) employed the geometry combination of a square duct with a centered circular core for the design of an oven for heat treatment of ceramic and metallic products. they studied a situation where the central core is solid. combined natural convectionconduction and radiation heat transfer in discretely open cavity was studied by (dehgham et al, 1996) and (bello-ochende and adegun, 2002) also worked on combined convective and radiative heat transfer in a tilted, rotating, uniformly heated square duct with a centered circular cylinder. the work under investigation is to augment heat transfer in heat exchangers using geometric combination of a rectangular duct and a circular core. the working fluid flows between the inner surface of the rectangular duct and outer surface of the circular cylinder. manal h. al-hafidh al-khwarizmi engineering journal, vol.4, no.4, pp 45-56 (2008) 46 2. mathematical model: the schematic drawing of the geometry and the cartesian coordinate system employed in solving the problem is shown in fig.(1). fig. 1. schematic of the problem geometry. the fluid flows between the circular tube and the rectangular duct (annulus). this annulus is symmetrical about y-axis (∂/∂x = 0). the width and height of the channel are l and h respectively. the diameter and radius of tube are d and r respectively and the hydraulic diameter is d: )1...( )( )(2 * 4 2     rlh rhl p a d   the flow is upward, steady state, hydrodynamically and thermally fully developed laminar flow. symmetrical three-dimensional flow (symmetry about y-axis). the working fluid is assumed absorbing and emitting. heat transfer mechanism is convection (free-forced) and radiation. viscous dissipation affect in energy equation is negligible. boussineq approximation is used which means that the fluid density is assumed constant except when it directly causes buoyant forces (in momentum equation). all other fluid properties are assumed constant (newtonian fluid). the axial (z-direction) shown in fig.(1) is the predominant direction for the fluid flow. a viscous dissipation effect is neglected. axial conduction and radiation are assumed negligible following (yang and ebadian, 1991) for a condition that (re pr t / h) >10. governing equations: the governing equations are: continuity equation: )2...(0       y v x u momentum transport equation: the momentum transport equations in the x, y and z directions are respectively: )3...( 1 2          uv x p y x v x u u  )4...(cos)( 1 2             ttguv y p y v v x u u w )5...(sin)( 1 2             ttgwv z p y w v x w u w energy transport equation: in the absence of energy sources and viscous energy dissipation, the energy equation for steady flow, with radiation incorporated is:   )6...(44 2 2 2 2                      tt c k x y x y z t w y t v x t u w p r    the boundary conditions for these equations are: wtt  0 wvu manal h. al-hafidh al-khwarizmi engineering journal, vol.4, no.4, pp 45-56 (2008) 47 vorticity-stream function method: this method is used to eliminate the pressure terms in the two momentum equations in x and y directions by cross differentiation to the equations (3) and (4):                               3 3 2 3 2 2 22 y y yy u yx p y u v y u y v yx u u x u x u                                  8 pr cos 2 3 3 3 22 2 2 x ra xy u x v yx p xy v v y v y v x v u x v x u  by subtracting equation (7) from (8) and substitute vorticity definition, the following equation can be obtained:                9 pr cos 2 2 2 2 x ra y w x w y w v x w u  normalization parameters: the variables in the governing equations and boundary conditions are transformed to dimensionless formula by employing the following transformation parameters: d z z d y y d x  ,, v wd w v vd v v ud u         a v d t z t d v z p t t w w pr pr re 4 3 2  x v y udkt kk t n r r w        34 by using the relation above the equations (5, 6 and 9) became: vorticity definition equation:        10 2 2 2 2 yx   momentum equations:                          11 pr cos 2 2 2 2 x ra yxyxxy                           121 pr sin re4 2 2 2 2    ra y w x w y w xx w y energy equation:                         131 pr4pr pr 1 4 2 2 2 2 2   ntw yxyxxy the boundary conditions applicable to these equations are (fig. 2): (1) at the inlet of the duct (z = 0): 0 vu re,5.0  w (2) at the walls: 0 wvu 1  planesymmetry w xx             0  manal h. al-hafidh al-khwarizmi engineering journal, vol.4, no.4, pp 45-56 (2008) 48 fig. 2. the inlet and boundary conditions. 3. numerical solution: numerical grid generation: the elliptic transformation technique which was originally proposed by (fletcher, 1988) is applied to generate the curvilinear grid for dealing with the irregular cross sections. the transformation functions  yx ,  and  yx ,  are obtained to accommodate the irregular shape by solving the following partial differential equations:   ).14...( , 2 2 2 2 ag yx           ).14...( , 2 2 2 2 bs yx         where g and s are two functions which are defined to artificially adjust the density of the grid locally. using the curvilinear grid obtained, the governing eq. (10-13) and the boundary conditions are then discretized and solved in the computation domain   , . in this work, an (81 x 61) grid in the transformed domain    is adopted. fig.(3) shows typical grid generated for the channel cross section. the grid systems have been properly adjusted to be orthogonal locally at the boundaries. fig. 3. the generated grid. by using this method, the following general equation can be used to generate all the governing equations (10-13) in computational coordinates formula:     )15...(2 2 1 1   suj j     where represent the general variable which may be ω, w or θ and su is the source term. 4. finite difference formulation: the three-point central difference formula is applied to all the derivatives. each of the governing equations can be rewritten in a general form as:                         )16...(,,1,,1,, ,1,,1,,.     jijijijijiji jijijijijiji jsuasan awaeap   u = v = w = 0 ψ = ω = 0 θ = 0 y x y x inlet conditions r boundary conditions u = v = w = 0 ψ = 0, θ = 1 u = v = w = 0 ψ = 0, θ = 1 u = v = w = 0 ψ = 0 , θ = 1 u = v = w = 0 ψ = 0 , θ = 1 u = v = w = 0 ψ = 0, θ = 1 y x manal h. al-hafidh al-khwarizmi engineering journal, vol.4, no.4, pp 45-56 (2008) 49 where:                        cas can baw bae ap jiji jiji jiji jiji jijiji      ,, ,, ,1, ,1, ,,1, 2                      22 22 , 1,1, , , ,1,1 ,                         ji jiji ji ji jiji ji jc jb                      jijijiji jiji ji ji ji jsu j su ,,1,11,1 1,11,1 , ,1 , 2        in the equations above i and j indicate to the points of the grid in the generalized coordinates  and  respectively. as pointed out in (anderson, 1984) the relaxation method can be employed for the numerical solution of the eq. (10). for this study, the lsor method [fletcher, 1988 and anderson, 1984] is used to solve equations (11, 12 and 13). the convergence criterion for the inner iteration (errorin) of  is 10 -4 and for the outer iteration (errorout) of b is 10 -10 , where:        )17...(2 ,,,1  jijijiinerror        )18...( , 1 , ,     rp it ji it ji ji   where rp is the relaxation parameter and equal to 1.1 and it represent the number of iterations. the outer iteration is checked only for as follow: )19...(10 10 1      it b it b it b outerror   5. evaluation of heat transfer: the peripheral heat transfer is defined through the conduction referenced nusselt number as: local nusselt number: the peripheral local nusselt number on the walls of the channel is computed from [belloochende & adegun]: )20...( 1       b w l n nu   where n represent the normal outward unit vector. the mean nusselt number on the wall of the rectangular duct and circular tube is obtained by using simpson's rule: )21...( 1 ,  s lrc dsnu s nu where s represents the length of the wetted perimeter in the rectangular duct and circular tube. the mean nusselt number (nu) is a measure of the average heat transfer over the internal surface of the rectangular duct and the outer surface of the circular configuration. it is computed from the following equation [belloochende & adegun]: )22...( rrcc nucnucnu where, cc nuc is a measure of average heat transfer from the outer surface of the circular core while cr nur corresponds to heat transfer from of the internal surface of the rectangular duct. cc and cr are the perimetric ratios for the heat transfer and are defined as: rlh lh c rlh r c r c         manal h. al-hafidh al-khwarizmi engineering journal, vol.4, no.4, pp 45-56 (2008) 50 6. results and discussion: results are presented for the following ranges of parameters: 0.1 ≤ gr ≤ 0.9 0.55 ≤ ar ≤ 1 0 ≤ n ≤ 100 0 ≤ t ≤ 10 re = 100, ra = 400, pr = 0.7 6.1 comparison of results: the comparison was made for the value of nul at the walls of the channel (rectangular duct and circular tube) with the previous results obtained by bello-ochende & adegun. these comparisons are shown in figs. (4a) and (4b). from these figures, a difference (approximately 10%) is found between these results. 0 0.2 0.4 0.6 0.8 1 gr 0 10 20 30 40 50 60 n u nu present study nu present study nu adegun nu adegun lr lc lr lc l re = 100, ra = 400 n = 5, t = 1, ar = 1 pr = 0.7,    fig.4a. comparison results (without radiation). 0 0.2 0.4 0.6 0.8 1 gr 0 10 20 30 40 50 60 n u nu present study nu present study nu adegun nu adegun lr lr lc lc l re = 100, ra = 400 n = 5, t = 1, ar = 1 pr = 0.7,    fig.4b. continued (with radiation). the number of nodes in ξ and η directions has very small effect on the value of nusselt number on the walls of the channel as shown in figs (5a) and (5b). 0 0.5 1 1.5 2 p 0 2 4 6 8 10 12 14 n u 41 x 61 61 x 61 81 x 61 l r r * re = 100, ra = 400 gr = 0.5, ar = 1 n = 5, t = 1, pr = 0.7    fig.5a. the variation of nulr on the rectangular duct walls with the number of nodes (along ξ). 0 0.5 1 1.5 2 p 0 2 4 6 8 10 12 14 n u 81 x 41 81 x 61 81 x 81 l r r * re = 100, ra = 400 gr = 0.5, ar = 1 n = 5, t = 1, pr = 0.7    fig.5b. continued (along η). 6.2 effect of gr: the heat transfer process through the channel suffers from many changes due to the layer of the still air in the corners as shown in figs (6-8). this layer cause to increase the thermal resistance and that lead to decrease the rate of heat transfer. the heat transfer rate through the wall of the circular tube is uniform and greater than that on the walls of the rectangular duct. the direction of the heat transfer from the walls towards the core of the manal h. al-hafidh al-khwarizmi engineering journal, vol.4, no.4, pp 45-56 (2008) 51 channel is shown by the isotherm lines. when gr is larger than 0.2, two cells will be generated and the center of these cells had a minimum temperature. as shown in figs (6-8), the volume of these cells decreased with increasing gr value and that because of the decreasing of the confined area between the walls and the temperature of these cells increased. fig.6. streamlines and isotherms for gr = 0.4. fig.7. streamlines and isotherms for gr = 0.6. fig.8. streamlines and isotherms for gr = 0.8. 1 1 1 1 1 1 1 2 2 2 2 2 2 3 3 3 3 3 3 4 4 4 4 4 5 5 5 5 5 6 6 6 6 6 7 7 7 7 7 8 8 8 8 9 9 9 9 1 0 10 1 0 10 1 1 1 1 1 1 11 1 2 1 2 1 2 1 3 13 1 3 1 4 1 41 4 1 5 15 0.0113142 14 0.010542 13 0.00976985 12 0.00899768 11 0.00822551 10 0.00745335 9 0.00668118 8 0.00590901 7 0.00513685 6 0.00436468 5 0.00359251 4 0.00282034 3 0.00204818 2 0.00127601 1 0.000503842  1 1 1 1 2 2 2 2 3 3 3 3 4 4 4 4 4 5 5 5 5 5 6 6 6 6 6 7 7 7 7 7 8 8 8 8 8 9 9 9 9 1 0 1 0 1 0 10 1 1 11 1 1 11 12 1 2 1 2 12 1 3 13 1 3 1 3 13 14 14 1 4 1 4 14 15 1 5 1 5 15 15 0.98977 14 0.97954 13 0.96931 12 0.959079 11 0.948849 10 0.938619 9 0.928389 8 0.918159 7 0.907929 6 0.897698 5 0.887468 4 0.877238 3 0.867008 2 0.856778 1 0.846548  1 1 2 2 3 3 4 4 4 5 5 5 5 6 6 6 6 6 6 7 7 7 7 7 7 8 8 8 88 9 9 9 1 0 1 0 10 1 0 1 1 1 1 1 2 12 1 3 1 3 14 1 5 1 5 15 0.00038869 14 0.000345546 13 0.000302403 12 0.000259259 11 0.000216115 10 0.000172972 9 0.000129828 8 8.66846e-05 7 4.35409e-05 6 3.97285e-07 5 -4.27463e-05 4 -8.589e-05 3 -0.000129034 2 -0.000172177 1 -0.000215321  1 2 2 3 3 3 4 4 4 5 5 5 5 6 6 6 6 7 7 7 7 7 7 8 8 8 8 8 8 9 9 9 9 9 9 9 10 1 0 10 1 0 1 0 1 0 11 1 1 11 1 1 1 1 11 12 1 2 12 12 1 2 1 2 12 13 1 3 13 1 3 1 3 13 14 1 4 14 14 1 4 1 4 14 15 1 5 15 1 5 1 5 15 15 0.998295 14 0.996589 13 0.994884 12 0.993178 11 0.991473 10 0.989768 9 0.988062 8 0.986357 7 0.984651 6 0.982946 5 0.98124 4 0.979535 3 0.97783 2 0.976124 1 0.974419  1 1 2 2 3 3 3 4 4 4 4 5 5 5 5 6 6 6 6 7 7 7 7 7 7 8 8 8 8 8 8 8 9 9 9 9 9 9 9 10 1 0 10 10 1 0 1 0 10 10 0.999126 9 0.998252 8 0.997378 7 0.996504 6 0.99563 5 0.994756 4 0.993883 3 0.993009 2 0.992135 1 0.991261  1 1 2 3 33 4 4 4 4 5 5 5 5 5 5 6 6 6 7 7 7 8 8 8 9 9 1 0 1 0 1 1 1 1 12 1 2 12 5.55211e-05 11 4.76864e-05 10 3.98516e-05 9 3.20169e-05 8 2.41821e-05 7 1.63474e-05 6 8.51263e-06 5 6.77871e-07 4 -7.15688e-06 3 -1.49916e-05 2 -2.28264e-05 1 -3.06611e-05  manal h. al-hafidh al-khwarizmi engineering journal, vol.4, no.4, pp 45-56 (2008) 52 streamlines are shown in figs. (6-8). with increasing the value of gr, two cells will be generated inside this big cell. the maximum value of stream function is at the center of these two cells. when gr increased greater than 0.2, two additional cells will be generated and their centers have the minimum value of the stream function. these cells are generated because of the difference between the velocity of particles in the hot and cold regions, in addition to the impact between the rising and lowering air streams. the volume of these cells will be decreased with increasing in gr value until small four cells generated. fig. (9) illustrates the variation of mean nusselt number nu through the channel with gr value. it is shown that when gr increased then nu increased, this is due to the effect of increasing in the surface area of the circular wall. this increasing of the surface area leads to increase the rate of heat transfer. the radiation effect is very small for the small values of gr. this effect increased with increasing in gr value because of increasing the heat gain by air with decreasing in the air quantity. fig. 9. the variation of nu with gr the bulk temperature of air increased with increasing in gr value as shown in fig. (10) and that because of increasing in the surface area which participating in the heat transfer process and that result to increase the rate of heat transfer. fig.10. the variation of the bulk temperature with gr. 6.3 effect of ar: figs. (11-13) show the streamlines and isotherms of the fluid flow and heat transfer process. when ar is equal to 1, four cells will be generated. with variation in ar, the behavior of the streamlines will be changed. when ar decreased the two cells near the circular tube is beginning to vanish. when ar decreased less than 0.6, two cells will be occupied most the confined area between the walls of the rectangular duct and the circular tube. the intensity of these cells will be increased with decreasing in ar. while, the value of the stream function of the center of these cells will be decreased because of decreasing the confined area between the walls. for the isotherms, it shows that when ar decreased the two cells tends to be near top and bottom the channel walls since the outer and internal boundary of this channel is closer of low values. 0 0.2 0.4 0.6 0.8 1 gr 0 10 20 30 40 50 60 70 n u without radiation with radiation ar= 1, n = 5, t = 1, re = 100, ra = 400, pr = 0.7    1 1 2 2 3 3 4 4 4 4 5 5 5 5 5 5 6 6 6 6 6 7 7 7 7 7 7 8 8 8 8 8 9 9 9 9 1 0 10 10 1 1 1 1 1 1 1 1 1 2 12 12 1 3 13 14 1 4 15 15 0.00089873 14 0.000806143 13 0.000713557 12 0.00062097 11 0.000528383 10 0.000435796 9 0.00034321 8 0.000250623 7 0.000158036 6 6.54494e-05 5 -2.71373e-05 4 -0.000119724 3 -0.000212311 2 -0.000304898 1 -0.000397484  1 1 2 2 2 2 3 3 4 4 4 5 5 5 5 6 6 6 6 6 6 7 7 7 7 7 7 8 8 8 8 8 8 8 9 9 9 9 9 9 1 0 10 10 1 0 1 0 10 1 1 11 11 1 1 1 1 11 1 2 12 12 1 2 1 2 12 13 1 3 13 1 3 1 3 13 1 4 14 14 1 4 1 4 14 1 5 15 1 5 1 5 1 5 15 15 0.997324 14 0.994648 13 0.991971 12 0.989295 11 0.986619 10 0.983943 9 0.981267 8 0.97859 7 0.975914 6 0.973238 5 0.970562 4 0.967886 3 0.965209 2 0.962533 1 0.959857  manal h. al-hafidh al-khwarizmi engineering journal, vol.4, no.4, pp 45-56 (2008) 53 fig.11. streamlines and isotherms for ar = 0.6. fig.12. streamlines and isotherms for ar = 0.8. 0 0.25 0.5 0.75 1 gr 0.75 0.775 0.8 0.825 0.85 0.875 0.9 0.925 0.95 0.975 1  without radiation with radiation ar= 1, n = 5, t = 1, re = 100, ra = 400, pr = 0.7   b fig.13. streamlines and isotherms for ar = 1. fig. (14) illustrates the variation in the mean value of nu with ar. this figure shows that when ar is increased nu will decrease because of the increasing in ar lead to increase the cross section area, and that led to increase the intensity of the air vorticity and the effect of the buoyancy force which then decrease the rate of heat transfer. the effect of radiation is noted for ar < 0.8, but with increasing in ar, the effect of radiation will be neglected. 0.5 0.6 0.7 0.8 0.9 1 ar 12 13 14 15 16 17 18 19 20 21 22 n u without radiation with radiation gr= 0.5, n = 5, t = 1, re = 100, ra = 400, pr = 0.7    fig.14. the variation of nu with ar 6.4 radiation effect: the correlation equation for the plotted curves is presented to know the radiation effect on the rate of heat transfer. this equation is made by using the curve fitting method with using data fit program. the form of this equation is: 3 21 a aanu  where a1, a2 and a3 are coefficients and are tabulated in table (1). for the bulk temperature, the effect of radiation will be written as follow: 3102.6304.13287.12  grb (with radiation) 3104.5763.16747.15  grb (without radiation) 1 2 2 2 2 3 3 3 3 4 4 4 4 5 5 5 6 6 6 6 7 7 8 8 9 9 10 1 0 12 12 0.000173375 11 0.000155548 10 0.000137722 9 0.000119896 8 0.00010207 7 8.42433e-05 6 6.6417e-05 5 4.85907e-05 4 3.07644e-05 3 1.29381e-05 2 3.6818e-06 1 -5.34832e-07  1 1 2 2 3 3 4 4 4 5 5 5 5 6 6 6 6 7 7 7 7 7 7 8 8 8 8 8 8 8 0.997629 7 0.995258 6 0.992887 5 0.990515 4 0.988144 3 0.985773 2 0.983402 1 0.981031  1 1 1 2 2 3 3 3 4 4 4 4 5 5 5 5 6 6 6 6 6 7 7 7 7 7 8 8 8 8 8 9 9 9 9 9 1 0 10 10 1 0 1 0 10 11 1 1 11 1 1 1 1 11 11 0.997648 10 0.995295 9 0.992943 8 0.99059 7 0.988238 6 0.985886 5 0.983533 4 0.981181 3 0.978828 2 0.976476 1 0.974124  1 1 1 2 2 2 2 2 3 3 3 3 4 4 4 4 5 5 5 6 6 6 6 7 7 7 8 8 8 9 9 10 1 0 11 1 2 1 3 13 13 0.000317373 12 0.000289816 11 0.000262258 10 0.000234701 9 0.000207144 8 0.000179587 7 0.000152029 6 0.000124472 5 9.69146e-05 4 6.93573e-05 3 4.18e-05 2 1.42427e-05 1 -1.33146e-05  manal h. al-hafidh al-khwarizmi engineering journal, vol.4, no.4, pp 45-56 (2008) 54 0 25 50 75 100 otical thickness, conduction-radiation parameter 12 12.5 13 13.5 14 14.5 15 n u t 10 n ar = 1, gr = 0.5, re = 100, ra = 400, pr = 0.7    * optical thickness, conduction-radiation parameter table 1 the radiation effect  with radiation without radiation a1 a2 a3 a1 a2 a3 gr 7.577 44.648 3.1 6.5677 39.176 2.887 ar 12.117 0.58597 4.55 13.0733 0.03231 9.0938 6.5 effect of radiation properties: fig. (15) illustrates the effect of optical thickness t and conduction-radiation parameter n. it is shown that when t and n are increased nu will be increased, but the increasing in t will be greater than n, this is because the optical thickness is powered to 2 into the radiation term as shown in eq.(10). fig.15. the effect of radiation properties. 7. conclusions: it can be concluded from the present work that: (1) the rate of heat transfer is increased by 87% with increasing gr from 0.1 to 0.9 and the heat transfer process is become conduction at gr = 0.9. (2) nu increases by 45% with decreasing in ar from 0.55 to 1. (3) the isotherms show two cells formed for gr > 0.2 and the streamlines show two cells formed for gr < 0.4 but four cells will be generated when gr ≥ 0.4 until 0.8. (4) the radiation effect on the heat transfer coefficient is known by making a correlation equations and this effect show that nu will be increased. (5) increasing the radiation properties (t, n), the radiation effect will be also increased. 8. nomenclature: a cross-sectional area (m 2 ) . ar aspect ratio (l/d). cp specific heat at constant pressure (j/kg.k). d major diameter (m). d hydraulic diameter (4a/ p * ). g acceleration due to gravity (m/s 2 ). gr geometric ratio (d/l). h heat transfer coefficient (w/m 2 . o c). h height of the rectangular cross section (m). j jacobean of direct transformation. k thermal conductivity of the working fluid (w/m. o c). kr volumetric absorption coefficient (1/m). l length of the rectangular cross section (m). n outward normal on the wall. n radiation-conduction parameter. nu mean nusselt number. nuc mean nusselt number for the circular surface. nur mean nusselt number for the rectangular duct. nulc local nusselt number. p the small pressure variation governing the flow distribution in manal h. al-hafidh al-khwarizmi engineering journal, vol.4, no.4, pp 45-56 (2008) 55 the cross stream plane (n/m 2 ). p average pressure over the duct cross section. p * wetted perimeter (m). pr prandtl number, . r radius (m). ra rayleigh number. re reynolds number . t optical thickness. t dimensional fluid temperature (k). ti dimensional inlet fluid temperature (k). tw wall temperature (k). u, v, w dimensional velocity in x, y and zdirections (m/s). u, v, w normalized velocity in x, y and zdirections. x, y, z dimensional cartesian coordinates (m). x, y, z dimensionless cartesian coordinates. 9. greek symbols: α coefficient of thermal expansion (m 2 /s). β thermal diffusivity (m 2 /s). ε emissivity. ξ, η dimensionless computational coordinates. θ normalized fluid temperature. θi normalized inlet fluid temperature. θb normalized bulk temperature. λ inclination to the horizontal (°). υ kinematic viscosity of the fluid (m 2 /s). ρ fluid density (kg/m 3 ). σ stefan boltzmann constant (wm 2 / k 4 ). ψ dimensionless stream function. ω dimensionless vorticity. 10. supscripts: b bulk c circle i inlet l local r rectangle w wall r radiation 11. references: [1] anderson a., tannehill c. and pletcher h. (1984), computational fluid mechanics and heat transfer, mcgraw-hill, washington. [2] bello-ochende f. l. (1985), a numerical study of natural convection in horizontal elliptic cylinders, revista brasileira de ciências mecânicas, vol. vii, no.3,pp.185207. [3] bello-ochende f. l. and adegun i. k. (1993), a perturbation analysis of combined free and forced laminar convection in tilted elliptic cylinders, the 6th international symposium on transport phenomena in thermal engineering, seoul, vol. iii, pp.121-125. [4] bello-ochende f. l. and adegun i. k. (2002), combined mixed convective and radiative heat transfer in a tilted rotating uniformly heated square duct with a centered circular cylinder international journal of heat and technology, vol. 20, no.1, pp.21-30. [5] dehghan a. a. and behnia m. (1996), combined natural convection–conduction and radiation heat transfer in a discretely heated open cavity, journal of heat transfer, vol. 118, pp.56-64. [6] dong z. f., ebadian m. a. and bigzadeh e. (1993), convective-radiative heat transfer in a square duct with a centered circular core, international journal of heat and fluid flow, vol. 14, no. 1, pp. 68-75. [7] fletcher c. a. j. (1988), computational fluid techniques for fluid dynamics 2, springer-verlag. [8] siegel r. (1985), analysis of buoyancy effect on fully developed laminar heat transfer in a rotating tube, journal of heat transfer, vol.107, pp. 338-344. [9] yang g. and ebadian m. a. (1991), thermal radiation and laminar forced convection in the entrance of a pipe with axial conduction and radiation, int. j. heat fluid flow, vol.12, no. 3 pp. 202-209. (2008 )56-45، صفحت 4، العذد 4 مجلت الخىارزمي الهنذسيت المجلذ هادي الحافظ لمنا 56 أنتقال الحرارة بالحمل المختلط واألشعاع خالل قناة مستطيلت مائلت مع أنبىب داخلي رائذ كاطع صيهىد منال هادي الحافظ جاٍؼت بغذاد /قسٌ اىهْذست اىَُناُّنُت الخالصت أّخقاه اىذزارة باىذَو االشؼاع اىَخخيط ىجزَاُ ٍسخقز خاله قْاة ٍسخطُيت ٍائيت ٍغ أّبىب دائزٌ داخيٍ ٍخغُز اىَىقغ درسج رقَُاً اىَؼادالث اىخٍ أسخخذٍج هٍ . حٌ اىخؼاٍو بَُناُّنُت إّخقاه اىطاقت اىذزارَت باىذَو واإلشؼاع بشنو ٍْفصو وفٍ آُ وادذ. ىجزَاُ حاً اىخطىر اىذواٍُت ثٌ اىً صُغت-ّسُابإلحٌ حذىَو هذٓ اىَؼادالث اىً ٍؼادالث بذوُ ودذاث ثٌ اىً صُغت داىت ا. (سخَزارَت، اىشخٌ وٍؼادىت اىطاقتإلا) حٌ . دذاثُاث ىبْاء شبنت اىْظاًإلجزاء جَُغ اىذساباث باسخخذاً ّظاً ٍطابقت اإلأسخخذٍج طزَقت اىفزوق اىَذذدة . اىَطابقت ىيجسٌ دذاثُاثإلا (1-0.55)وىْسبت باػُت ((0.9-0.1 ىذساب ٍؼاٍو االدخناك ورقٌ ّسيج ىذاىت ٍسخقزة وىْسبت شنو حخزاوح بُِ ٩٠بْاء بزّاٍج فىرحزاُ ، ٍؼاٍو (t ≤ 10 ≥ 0)، اىسَل اىبصزٌ re = 100 ، رقٌ رَْىىذra = 400، رقٌ راَيٍ pr = 0.7)) وىخىاص جزَاُ رقٌ بزاّخو ىيَذَاث اىسابقت اىْخائج بُْج سَادة أّخقاه اىطاقت اىذزارَت بخأثُز اإلشؼاع وأُ λ = 45 وساوَت اىَُو (n ≤ 100 ≥ 0)اإلشؼاعاىخىصُو بصىرة ػاٍت، فأُ رقٌ ّسيج سىف َشداد ٍغ سَادة . إّخقاه اىطاقت اىذزارَت ٍِ سطخ األسطىاّت أمثز ٍِ أّخقاىها ٍِ سطخ اىَجزي اىَسخطُو هذا . ػْذ اضافت حأثُز االشؼاع اىً ػَيُت اّخقاه اىذزارة فأُ ٍؼذه اّخقاه اىذزارة سىف َشداد. arبَُْا َقو ٍغ أسدَاد n وgr ، tمالً ٍِ أُ سَادة خىاص االشؼاع حؤدٌ اىً سَادة حأثُز االشؼاع و باىخاىٍ سَادة ٍؼذه اّخقاه . ar و ٍغ ّقصاُ grاىخأثُز َشداد ٍغ اسدَاد قَُت ىزسٌ ٍخططاث مْخىرَت ىذاىت االّسُاب و حىسَغ درجاث اىذزارة ىَؼزفت سيىك اىهىاء خاله ػَيُت اّخقاه ٧أسخخذً بزّاٍج حنبيىث . اىذزارة . حٌ اىخىصو اىً ػالقت حصف حاثُز االشؼاع ػيً ػَيُت اّخقاه اىذيزارة. اىذزارة و حغُز هذا اىسيىك ٍغ حغُُز اىَؼاٍالث اىَؼخَذة <4d6963726f736f667420576f7264202d2035302d3635d4c8e1ed20e6e3cdd3e420e6dae3c7cf> al-khwarizmi engineering journal,vol. 13, no. 1, p.p. active vibration suppression of smart cantilever beam with sliding mode observer using two piezoelectric patches shibly a. al-samarraie* imad a. abdulsahib*** *department of control and systems engineering / **,***department of mechanical engineering / university of (received https://doi.org/10.22153/kej.2017.08.005 abstract this paper presents a vibration suppression control patch was used as an actuator element, while the other was used as a sensor. the controller design was designed via the balance realization reduction method to elect the reduced order model that is most controllable and observable. sliding mode observer was designed to estimate six states from the reduced order model but three states are only used in the control law. estimating a number of states larger than that used is in order to increase the estimation accuracy. moreover, the state estimation error is proved bounde states with the sliding mode observer, to elements. the control spillover problem was avoided, by deriving an avoi stability for the proposed vibration control design. attenuation ability of the proposed optimal control. for 15 mm initial tip able to reduce the tip displacement to about 0.1 experimental results showed a good performance of the proposed lqr control law and the sliding mode obser well a good agreement with theoretical results. keywords: smart materials, active vibration, piezoelectric, sliding mode 1. introduction active vibration control is a technique that used for suppression structural vibrations, using this technique to smart structures becomes of great interest and getting much more important. one way of making the structure a smart one is performed by the use of piezoelectric materials which can be used as sensors and actuators are flexible enough to be placed in a variety of places and have the capacity to work ranges of frequencies [1]. piezoelectric materials have simple mechanical properties, small volume, light weight, and good ability to perform vibration khwarizmi engineering journal,vol. 13, no. 1, p.p. 5065 (2017) active vibration suppression of smart cantilever beam with sliding observer using two piezoelectric patches samarraie* mohsin n. hamzah** imad a. abdulsahib*** department of control and systems engineering / university of technology **,***department of mechanical engineering / university of technology *email: 60132@uotechnology.edu.iq **email: dr.mohsin@uotechnology.edu.iq ***email: emad099@yahoo.com (received 27 april 2016; accepted 7 august 2016) https://doi.org/10.22153/kej.2017.08.005 this paper presents a vibration suppression control design of cantilever beam using two piezoelectric an actuator element, while the other was used as a sensor. the controller design was designed via the balance realization reduction method to elect the reduced order model that is most controllable and observable. estimate six states from the reduced order model but three states are only used in the control law. estimating a number of states larger than that used is in order to increase the estimation accuracy. estimation error is proved bounded. an optimal lqr controller is designed then using the states with the sliding mode observer, to suppress the vibration of a smart cantilever beam via the piezoelectric elements. the control spillover problem was avoided, by deriving an avoidance condition, to ensure the control design. the numerical simulations were achieved to proposed optimal control. for 15 mm initial tip displacement, the piezoelectric actuator found able to reduce the tip displacement to about 0.1 mm after 4s, while it was 1.5 mm in the open loop case. the current experimental results showed a good performance of the proposed lqr control law and the sliding mode obser well a good agreement with theoretical results. active vibration, piezoelectric, sliding mode observer, model reduction, lqr controller technique that is used for suppression structural vibrations, using becomes of getting much more important. smart one is by the use of piezoelectric materials, actuators. they a variety of places and have the capacity to work in wide iezoelectric materials es, small volume, nd good ability to perform vibration control [2]. one of the application of piezoelectric smart structures is the control and suppression of unwanted structural vibrations [3]. materials electricity is produced called direct effect. conversely, subjecting these materials to an electric field produce deformation, converse effect. the piezoelectric sensor senses the external disturbances and generates voltage due to the direct effect, while piezoelectric actuator produces force, due converse effect, that can be used as force [4]. modelling continuous mechanical structures subjected to dynamic loadings is not an easy task. al-khwarizmi engineering journal active vibration suppression of smart cantilever beam with sliding observer using two piezoelectric patches university of technology design of cantilever beam using two piezoelectric patches. one an actuator element, while the other was used as a sensor. the controller design was designed via the balance realization reduction method to elect the reduced order model that is most controllable and observable. the estimate six states from the reduced order model but three states are only used in the control law. estimating a number of states larger than that used is in order to increase the estimation accuracy. optimal lqr controller is designed then using the estimated beam via the piezoelectric condition, to ensure the asymptotic the numerical simulations were achieved to test the vibration piezoelectric actuator found open loop case. the current experimental results showed a good performance of the proposed lqr control law and the sliding mode observer, as reduction, lqr controller. control [2]. one of the application of piezoelectric smart structures is the control and suppression of unwanted structural vibrations [3]. in these is produced by pressure, onversely, subjecting these materials to an electric field produces a . the piezoelectric senses the external disturbances and direct effect, while piezoelectric actuator produces force, due to the can be used as a controlling continuous mechanical structures is not an easy task. shibly a. al-samarraie al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 5065(2017) 51 scarce analytical solutions for specific situations are available. the discretization of these structures is an alternative and basic step for further analysis. the finite element methods (fem) is an efficient tool for this purpose [5]. in the finite element modeling, the structure is modeled to retain large number of degrees of freedoms. in active vibration control, the use of smaller order model has computational advantages. therefore, it is essential to apply model reduction techniques for getting a reduced model for designing the control law. one of these techniques is based on balance realization method [6]. the approach taken for reduction the order of a given model based on removal the coordinates, that are the least controllable and observable. to implement this idea, a measure of the degree of controllability and observability is required [7]. for closed-loop system, it is not always possible to get a control law that cause eigenvalues to have the required and desired values. the system is completely controllable if every state variable can be affected in such a way as to cause it to reach a particular value within a finite amount of time by some unbounded control [6]. however, an alternative, more useful measure is provided for asymptotically stable systems of the form given by equations by defining the controllability gramian. gramian matrices can be used for checking if a system is controllable and observable [6]. the control of the vibration of a smart structure is usually performed via a controller that based on the reduced order model (rom). once a rom based controller is applied to the full order system, actuator forces will reduce the vibration of the lower modes. however, this will also influence the residual modes of the structure, producing undesirable vibration due to the unmodeled dynamics. this phenomenon is known as control spillover [9]. similarly, the sensor will sense the deflection from the lower modes as well as from the other modes, this is known as observation spillover. spillover effects are undesirable and may cause performance degradation and even system instability [10]. indeed, one way to avoid a spillover, which comes from the state estimation or observation process, is to use an observer for estimating the states with minimal error. numerous control strategies have been suggested to suppress the vibration of flexible structures for the flexible systems. some of these studies are state feedback control, linear quadratic regulator (lqr) approach [11], �� control, �∞ control [12] and sliding mode control [13]. the theory of optimal control is concerned with operating a dynamic system at minimum cost. the case, where the system dynamics are described by a set of linear differential equations and the cost is described by a quadratic function, is called the lqr problem. the settings of a regulating controller governing a controlled system are found by using a mathematical algorithm that minimizes a cost function with weighting factors. the cost function is a sum of the deviations of key measurements from their desired values. often the magnitude of the control action itself is included in this sum so as to bound the energy spent by the control action [11]. the lqr is the most commonly used controller in smart structures [1417]. state measurement is required for the controller; an observer is usually designed to estimate the states. observers are dynamic systems that can be used to estimate the unavailable state variables of a plant. luenberger observer [18], used a dynamical linear system to generate estimates of the plant states. in some cases, some of the inputs to the system are unknown. this led to the development of the unknown input observer. for the smart beam, which modeled by fem with a reduced number of states, the remaining states which are acting on the reduced model can be regarded as unknown inputs. sliding mode theory is a robust control approach in treating disturbances and modeling uncertainties through the concepts of sliding surface design and equivalent control [13]. based on the equivalent control, the sliding mode control theory can be used as an observer to estimate the system states. the sliding mode observer (smo) are able to ensure finite-time convergence of the output estimation error even in the presence of the unknown inputs. additionally, they can be used to reconstruct unknown inputs using equivalent control methods [19]. the method v-function, [20], has been used to formulate sliding mode observers design which lead the state estimation errors approach to zero asymptotically with matched uncertainties. the main advantage of using sliding-mode observers is that, while in sliding, they are insensitive to the matched unknown inputs. moreover, they can be used to reconstruct unknown inputs, which could be a combination of system disturbances [21]. many researchers were interested in designing sliding mode observers for uncertain dynamical systems; such as utkin et al. [22], walcot et al. [23], zak et al. [24], edwards et al. [19], and slotine et al. [25]. shibly a. al-samarraie al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 5065(2017) 52 this paper focuses on designing an optimal lqr controller by using sliding mode observer to attenuate the vibration of a smart cantilever beam. piezoelectric elements are used as an actuator and a sensor. the utilized model for control design purpose is the reduced order model that is obtained according to the balance realization method. based on the equivalent control, the smo is designed with estimation error related to the rom. to avoid control spillover, an avoidance condition, using complete system dynamics, was derived. 2. modeling of smart cantilever beam figure (1) depicting the smart cantilever beam considered in this work. the beam is bonded with a pair of piezoelectric patches, working as a sensor and an actuator, at the indicated position. the piezoelectric material used in this work is the lead-zirconate-titanate (pzt). using eulerbernoulli beam equation, the partial differential equation of the beam can be written as [26]; �� �����, ���� � �����, �� � � 0 …(1) where �� � �� ��⁄ , ���, �� is the deflection along the �-axis, � is the young's modulus, � is the moment of inertia, � is the cross sectional area, and � is the density. equation (1) can be solved by using the assumed mode approach, which yields finite dimensional ordinary differential equation set. fig. 1. flexible smart cantilever beam. the dynamic equation of the smart structure is obtained by using both regular beam element and piezoelectric beam elements. the mass and stiffness matrices of the smart structure include the mass and stiffness of the sensor/actuator [27]. the smart beam, shown in figure (1), is modelled in state space form using the fem, the beam is divided into six equal finite elements. the sensor and actuator were integrated on the top and bottom surfaces at the second element from the fixed end of the beam. a beam element is considered with two nodes at its end. each node is considered to have two degrees of freedom (dof), i.e. translation (in � direction) and rotation. the mass and stiffness matrix are derived using shape functions for the beam element. the inertia force appears in the governing differential equation of the beam, equation (1), involves a fourth order derivative w.r.t. �, and a second order derivative w.r.t. time (acceleration). the solution of this equation is assumed as a cubic polynomial function [28]. ���� � �� � �� � � �� �� � �� �� …(2) where ���� is displacement function which satisfies the fourth order partial differential equation, here x is the local coordinate of the element. the constants �� to �� be obtained by using the boundary conditions at both the nodal points (fixed end and free end). and it can be represented in a matrix form as, [29] ���� ��� � !� = � 1 0 0 00 1 0 01 # #� #� 0 1 2# 3#�! �� �������� �! …(4) where �� , � , �� , and � are the degree of freedom at node 1 and 2, respectively, and # is the length of the element. accordingly, the mass matrix is given as, [29] )* � �* �* + , , -.� /0 � 1020/0��3 45 56 156 22#* 54 :13#*22#* 4#*� 13#* :3#*�54 13#* 156 :22#*:13#* :3#*� :22#* 4#*� ;< <= …(4) where )* is the mass matrix of regular beam, , is the shape function. also for the strain energy the stiffeness matrix is given by [29]: >* � �* �* + ,� ,� .� /0 � ?0 @0/ a � 12 6# :12 6#6# 4#� :6# 2#�:12 :6# 12 :6#6# 2#� :6# 4#� ! …(5) where >* is the stiffeness matrix of regular beam, eventually the equation of motion according to the lagrangian equation is [30]: x z y shibly a. al-samarraie al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 5065(2017) 53 )* bc � >*b � d* …(6) or 1020��3 45 56 156 22#* 54 :13#*22#* 4#*� 13#* :3#*�54 13#* 156 :22#*:13#* :3#*� :22#* 4#*� ;< <= 45 56��c � c��c � c� ;< <=� + ?0 @0/ a 45 56 12 6#* :12 6#*6#* 4#*� :6#* 2#*�:12 :6#* 12 :6#*6#* 2#*� :6#* 4#*� ;< <= ���� ��� � !� � � e�)�e�)� ! …(7) where e� , e�, )�, )� are the forces and the bending moments acting on nodes 1 and 2 respectively figure (1). when pzt patches are assumed as euler-bernoulli beam elements the elemental mass and stiffness matrices of pzt beam element can be computed in similar fashion as [31]: )f � 1g2g/g��3 455 56 156 22#f 54 :13#f22#f 4#f� 13#f :3#f�54 13#f 156 :22#f:13#f :3#f� :22#f 4#f� ;<< <= …(8) >f � ?g @g/ a 455 56 12 6#f :12 6#f6#f 4#f� :6#f 2#f�:12 :6#f 12 :6#f6#f 2#f� :6#f 4#f� ;<< <= …(9) in which �� � �* �* � 2�f �f is the flexural rigidity and �� � h��*�* � 2�f�f ) is the mass per unit length, �f is the thickness of pzt patches, and �f � * ia�� � h�j k il 0� m�. so the element mass and stiffness matrices are: )n � � � #*420 45 56 156 22#* 54 :13#*22#* 4#*� 13#* :3#*�54 13#* 156 :22#*:13#* :3#*� :22#* 4#*� ;< <= …(10) >n � ? @ /g a 455 56 12 6#* :12 6#*6#* 4#*� :6#f 2#*�:12 :6#* 12 :6#*6#* 2#*� :6#* 4#*� ;<< <= … (11) 2.1. sensor and actuator equations the sensor equation is derived from the direct piezoelectric equation, which is used to calculate the total charge created by the strain in the structure. the output charge can be transformed into the sensor current o��� [32]: o ��� � p q�� h + ,�-br .� �sl/0�s …(12) where, z = 0� � �j and ,t is the second spatial derivative of the shape function, q�� is the piezoelectric stress constant. the output current of the piezoelectric sensor measures the moment rate of the flexible beam. this current is converted into the open circuit sensor voltage uv��� using a signal-conditioning device with the gain gx. thus [30]: uv��� � [ 0 : z[p q�� h 0 z[ p q�� h ] 45 56�r � r��r � r� ;< <= � ]� [ 0 : 1 0 1] 45 56�r � r��r � r� ;< <= � ^-br …(13) where ][ � z[ p q�� h and ^ is a constant vector depends on the type of sensor, its characteristics and its location on the beam. the actuator equation is derived from the converse piezoelectric equation. the strain developed _� by the electric field �̀ on the actuator layer is given by [33]: _ � .�̀ …(14) where, �̀ � ai� � i is the electric field, and uj��� is the input voltage applied to the piezoelectric actuator in the thickness direction �j. then the stress bj that developed by the actuator is given by: [34] bj � �f .�� kcd �e� i m ...(15) where �f is the young’s modulus of the piezoelectric and .�� is piezoelectric strain constant. the bending moment of the piezoelectric element is given by: .)j � �f �f f��f�� …(16) shibly a. al-samarraie al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 5065(2017) 54 the resultant moment )j acting on the beam element due to the applied voltage uj is determined by integrating the stress in equation (15) throughout the structure thickness as: )j � �f .��p uj��� …(17) the control force d[ g/ produced by the actuator that is applied on the beam element is obtained as [30]: d[ g/ � �f.��h p [ :1 0 1 0 ]uj��� …(18) alternatively, d[ g/ can be expressed as: d[ g/ � ℎ uj ��� …(19) ℎ � �f .�� h p [ :1 0 1 0 ]i …(20) 3. dynamic equation of smart structure the element mass and stiffness matrices, equation (10) and equation (11), can be assembled using the standard fem procedure, to obtain the global mass and stiffness matrices of the entire beam. the beam is divided into six finite elements with two piezo-patches placed at the specified location. the equation of motion of the smart structure is given by [28]: ) b c � >b � dn� � d[ g/ � d …(21) where ), >, dn� , d[ g/ and d are the global mass matrix, stiffness matrix, external force vator, the controlling force vector (from the actuator), and the total force coefficient vector, respectively. the generalized structural modal damping matrix j is introduced into equation (21) by using[35, 36]: j � k) � l> …(22) where k and l are the frictional damping constant and the structural damping constant respectively. when applying the cantilever beam boundary condition, the system equation of motion for the six element cantilever beam is: ) b c � jbr � >b � d …(23) for free vibration condition dn� equal to zero, so the remaining applied force on the system is the controlling force d[ g/ exerted by the controller. 3.1 state space model of the smart beam model reduction in modern control theory needs a state space form for the mathematical model of a plant. consequently, the mathematical model of smart flexible cantilever beam can be written in state space form as follows [37]; let b � mb�b�n=m����n � � , br =obr�br�p=o�r��r�p=m����n, and bc � o�r��r�p, then the smart cantilever beam state space model is; ) o�r��r�p � j m����n � > m����n � d[ g/ …(24) which yields to ��r��r��r��r�! � m 0 �:)q� > :)q�jn � ��������! � m 0)q�ℎ n r��� …(25) and in a matrix form �r � ����� � sr��� …(26) where � � ���������! , � � m 0 �:)q� > :)q� jn , s � m 0)q�ℎ n and r��� � uj���. with appropriate zero and identity matrices dimensions. the sensor voltage is taken as the output of the system and the output equation is obtained as: ���� � uv��� � ^-br � ^m����n ...(27) thus, the sensor output equation in state space form is given by: ���� � [0 ^] ���������! or, ���� � t���� …(28) where t � [0 ^]. eventually, the single input single output state space model of the smart beam is given by equations (26) and (28): ��r � �� ��� � sr���� � t���� u …(29) with shibly a. al-samarraie al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 5065(2017) 55 �� � m 0 �:)q� > :)q� jn��∗��s � m 0)q�ℎ n��∗� t � [0 ^]�∗�� wxy xz …(30) 3.2. model reduction using the fem the structure is modeled to retain large (but finite) number of dof. in active vibration control, the use of smaller order model has computational advantages. therefore, it is necessary to apply a model reduction technique to the state space representation [6]. in this work the 24 th order system model, obtained from the fem modelling, is reduced to the three order using a model reduction technique based on balance realization. in this approach the state coordinate basis is selected such that the controllability and observability grammians are diagonal matrix and equal , normally with the diagonal entries of σ in descending order the state space representation is then called balanced realization [6]. to implement this idea, a measure of the degree of controllability and observability is needed. however, an alternative, more useful measure is provided for asymptotically stable systems of the form given by equations by defining the controllability grammian, denoted by {|, as [6]: {|� � + q2 ∞3 ss-q2} .� …(31) and the observability grammian, denoted by {~, as [6]: {~� � + q2} ∞3 t-tq2 .� …(32) where the matrices �, s, and t are defined in equation (30). the properties of these matrices provide useful information about the controllability and observability of the closedloop system. if the system is controllable (or observable), the matrix {| (or {~) is nonsingular [38]. these grammians characterize the degree of controllability and observability by quantifying just how far away from being singular the matrices {| and {~ are [6]. applying the idea of singular values as a measure of rank deficiency to the controllability and observability grammians yields a systematic model reduction method. the matrices {| and {~ are real and symmetric and hence are similar to a diagonal matrix. there is equivalent system for which these two grammians are both equal and diagonal. such a system is called balanced system, and {| and {~ must satisfy the following two liapunov-type equations: [39] �� {|� �{|� �� :ss-� {~� �{~� � � :t-t� …(33) now to transform the system to a balance realization form, the determination of a transformation matrix �� that will transform the system in equation (29) to: ��r ′ � �′�′ � s′r� � t′�′ � jr u …(34) is required, where �′ � ��q���� , s′ ���q�s and t′ � t�� . the controllability and observability grammians matrices are diagonal and equal {�| � {�~ � � � .o���b�, b�, …… . , b�� where {�| and {�~ are the controllability and observability grammians for system after applying the transformation � and the numbers b� are the singular values of the grammians and are ordered such that b� > b�l� , o � 1,2,… . . , � therefore, the pair ��′, s′� could be uncontrollable pair since some of b� could be equal to zero. indeed, there exist a subsystem, i.e. a reduced order model, which is still controllable and observable. choosing the matrix �� in the form �� � zq��σ �� ...(35) the grammians {[� and {~� will transformed to become equal and transform the system in equation (29) to a balanced realization form. namely, {�|= {�� =σ …(36) where σ can be written in terms of two set of the singular values b��� and b��� as ∑ � ob��� 00 b���p …(37) in this representation b��� describes the “strong” sub-systems to be retained and b��� the “weak” sub-systems to be deleted. conformally partitioning the matrices as shibly a. al-samarraie al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 5065(2017) 56 � �′ � o��� ������ ���ps′ � os�s�p t′ � [t� t�] wxy xz …(38) and truncating the model, retaining ��g � ���, sg � s� and tg � t� as the reduced system, and deleting the “weak“ internal subsystems [6]. 4. lqr state feedback control design the lqr is an optimal control approach to determine control signals that will cause a process to satisfy some physical constraints, and at the same time (maximize or minimize) a chosen performance index or cost function [11]. to design an lqr control, to the reduced order model of the smart beam, the reduced model (rm) and the residual model (rsm) [9] are presented here as follows; according to the balance realization the linear state model for the cantilever beam, as given in equation (34) are rewritten as follow; [29] ��rg � ��g�g � ����� � s�r�r� � ��g�g � ����� � s�r� � tg�g � t��� � …(39) where �g ∈ ℛg , is the reduced model states, �� ∈ ℛ�qg is the residual model states, and � � � ��gg×g ���g×��qg���g��qg�×g �����qg�×��qg��, s � � s�g×�s���qg�×��, t � �tg�×g t��×��qg�� the pair ���g , s�� is the controllable pair and ���g , tg� is the observable pair with highest controllability and observability grammian. from equation (39), the reduced model of the transformed model, which given in equation (34), is �rg � ��g�g � s�r …(40) note that � represents also the number of the states that will be used in the control design. in the second step the performance index �, is defined for the linear regulator problem as [6]; � � ��+ ��g-� �g � r-� r�∞ .�, …(41) where � and � are symmetric positive definite weighting matrices. the larger the matrix �, the more emphasis is placed by optimal control on returning the system to zero, since the value of x corresponding to the minimum of the quadratic form �g-� �g is � � 0. on the other hand, increasing � has the effect of reducing the amount, or magnitude, of the control effort allowed [6]. the optiumal control law that will minimize � is given by [40]. r��� � :�q� s������ � :>������� …(42) where � is the solution to the algebraic riccati equation [15]. ���� : �s��q� s�-� � ��g � � ���g � 0 ...(43) the linear controller, as in equation (42), that grantted asymptotic stabilty of the reduce model, may also cause the instability for the system dynamic. this type of instability is named as the control spillover. 4.1 control spillover problem and avoidance condition. spillover phenomenon occurs because that the unmodeled dynamics, which are not included in reduced order model, is excited by the control input as in the case of the reduced model. as a result the complete system model may have positive eigenvalue that leads to system instability. in order to avoid the control spillover, an avoidnace condition is derived as follows; let the matrix ∆ be defined as; δ � o���g : s�>� ������g : s�>� ���p …(44) which represents the whole model matrix after applying the proposed lqr control. in order to avoid control spillover the matrix δ must be hurwitz with its minimum absolute real eigenvalue is larger than theabsolute real eigenvalue of the matrix � equation (29). namely, if ��| represent the real term to eigenvalue of δ and ��~ represent the real term to eigenvalue of a then the avoidance condition is; shibly a. al-samarraie al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 5065(2017) 57 �| � min�£�→�¥��|¥ > min�£�→�¥��~¥ � �~ when difference between �| and �~is large,the vibration is attenuated effectively since the eigenvalue placed at �~ is the dominant one which shaped the cantilever beam response. 5. sliding mode observer for a large scale system, like the vibration control problem, the control spillover is not the only source for instability. there is another source of instability comes from imperfect or unprecise estimation for the states that are required for feeding back in the control law [13]. in fact the only way to avoid spillover that comes from the state estimation or observation process is to use an observer that estimates the states with minimal error. in the present work the sliding mode observer (smo) is used to estimate the states which it required in the control law equation (42). the advantage of using smo is to ensure that the difference between the system and observer outputs convergence to zero in a finite-time even in the presence of the unknown inputs. additionally, the smo can be used also to reconstruct unknown inputs using equivalent control method [21]. in the present work, the unknown input represents the residual term ������� for the �g dynamics equation (39) and the corresponding reduced order model in equation (40). for the linear time invariant system; equation (39) ��rg � ��g�g � s�r � j¦ � � tg�g u …(45) where the unknown input ¦ � �� ∈ ℛ�qg and j � ��� ∈ ℛg×�qg. now decompose �g to �g � [�� ��]and tg to tg � [t� t�], then the output � is: � � tg�g � t��� � t��� …(46) where �� ∈ ℛgq�, �� ∈ ℛ�, t� ∈ ℛ�×�gq�� t� ∈ ℛ�, where one of the attached piezoelectric patches is used as a sensor, and det �t�� ≠ 0. note that � represents the number of the estimated states which it selected later equal to six. accordingly equation (45), in terms of �� and ��, can be written as ��r� � ����� � ����� � s�r � j�¦�r� � ����� � ����� � s�r � j�¦u …(47) where s� ∈ ℛ�gq��×�, s� ∈ ℛ�, j� ∈ ℛ�gq��×�qg and j� ∈ ℛ�×�qg. equation (47) can be written in terms of �� and � as follows; ��r� � �ª���� � �ª��� � s«�r � j¬�¦�r � �ª���� � �ª��� � s«�r � j¬�¦ � …(48) where �� is replaced by, �� � t�q��� : t���� …(49) and, �ª�� � ��� : ���t�q�t�, �ª�� � ���t�q�, �ª�� � t���� � t���� : �t���� � t�����t�q�t� �ª�� � �t���� � t�����t�q� s«� � s�, s«� � t�s� � t�s� j¬� � j�,, j¬� � t�j� � t�j�, since |t�| ≠ 0, the transformation matrix between ���, ��� and ���, ��, m��� n � ®� m����n � o��gq�� �̄gq��×�t� t� p m����n …(50) is nonsingular. to this end the proposed smo to the system dynamic model, as given in equation (48), is as follows; ��°r� � �ª���°� � �ª���° � s«�r : ±²�°r � �ª���°� � �ª���° � s«�r : ² � …(51) the error dynamics between the observer equation (51) and the system equation (48) is governed by �qr� � �ª��q� � �ª��q³ : ±² :j¬�¦qr³ � �ª��q� � �ª��q³ : ² : j¬�¦ � …(52) where q� � �°� : ��and q³ � �° : �. to examine the stability of the error dynamics, the equivalent control is utilized as follows; first the output error q³ is guaranteed to reach zero value in a finite time if ² is selected as a discontinuous function of q³ ² � �ª��q³ � ´ ∗ µ���q³� …(53) shibly a. al-samarraie al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 5065(2017) 58 where µ���q³� is the signum function defined as follows; µ��¶q³· � ¸ 1 od q³ > 0:1 od q³ < 0� …(54) and ´ is the discontinuous gain that must satisfy the following condition ´ > ¥�ª��q� : j¬�¦ ¥ …(55) if ´ satisfies the inequality (55), then the sliding motion will ocuure on the sliding surface q³ � 0 after a finite time. by taking the initial condition for observer design as; ��°�, �°� £3 � �0, ��0�� …(56) and with ² as in equation (53), we have q³ �0, qr³ � 0 from the first instant, i.e. ∀� ≥ 0. the error dynamic stability based on the equivalent control is examined here as follows; ¼qr� � �ª��q� � �ª��q³ : ±² : j¬�¦qr³ � �ª��q� � �ª��q³ : ² : j¬�¦ �n½ � ¼qr� � �ª��q� : ±²n½ : j¬�¦0 � �ª��q� : ²n½ : j¬�¦ � , which yields ¼qr� � �ª��q� � �ª��q³ : ±² : j¬�¦qr³ � �ª��q� � �ª��q³ : ² : j¬�¦ �n½ � ¼ qr� � ¶�ª�� : ±�ª��·q� � ¶±j¬� : j¬�·¦²n½ � �ª��q� :j¬�¦ � ...(57) where ²n½ is computed at q³ � qr³ � 0. from equation (57) the unknown input term ¶±j¬� :j¬�·¦ in the estimation error dynamics will prevent the error q� from decaying exponantionaly to zero where it represents the error source in the observation process. in fact, this term is the source of observer spillover that may cause instability in system response. minimizing the error in the observation process is not an easy task since it influenced by the size of the reduced order model and the selected ± matrix as stated by the following proposition. proposition (1) the estimation error for the sliding mode observer as proposed in equation (57) will converge to a region around the origin bounded by ‖q�‖ � 2¿¶±j¬� : j¬�·-�¿‖¦‖ …(58) proof: consider the following candidate lyapunov function u � q�-�q� where � is a positive definite matrix. the time derivative of u is ur � q�-�-qr� � qr�-�q� � q�-�-à¶�ª�� : ±�ª��·q� � ¶±j¬� : j¬�·¦á � âq�-¶�ª�� : ±�ª��·� ¦-¶±j¬� : j¬�·-ã�q� � q�â�-¶�ª�� : ±�ª��· � ¶�ª�� : ±�ª��·-�ã q� � 2¦-¶±j¬� : j¬�·-�q� � :q�-q� � 2¦-¶±j¬� : j¬�·-�q� ≤ :q�-q� � 2¿¦-¶±j¬� : j¬�·-�q�¿ ≤ :q�-q� � 2‖¦‖¿¶±j¬� : j¬�·-�¿‖q�‖ � :‖q�‖� � 2‖¦‖¿¶±j¬� : j¬�·-�¿‖q�‖ � :â‖q�‖ : 2‖¦‖¿¶±j¬� : j¬�·-�¿ã‖q�‖ where �-¶�ª�� : ±�ª��· � ¶�ª�� : ±�ª��·-� � :� is the lyapunov equation. from the inequality above the condition ur ≤ 0 is satisfied in the compact set defined by ‖q�‖ > 2¿¶±j¬� : j¬�·-�¿‖¦‖ which means that the steady stat error is bounded by ‖q�‖ � 2¿¶±j¬� : j¬�·-�¿‖¦‖ where ¿¶±j¬� : j¬�·-�¿ � måæj� k�-¶±j¬� : j¬��¶±j¬� :j¬�·-�·n�/�. remark (1): in order to minimize the state estimation error we must select the ± matrix such that the norm ¿¶±j¬� :j¬�·-�¿ is minimal and, in the same time, the matrix ¶�ª�� : ±�ª��· is hurwitz as mentioned above. this task cannot easily be handled by try and error but we try in this work to select a suitable ± such that we get an appropriate estimation accuracy. shibly a. al-samarraie al 6. simulation results and discussion the simulation results for a cantilever beam, which is subjected to an initial tip deflection, are presented in this section where the matlab software is used to simulate the cantilever beam system. the physical and ge specifications for the beam are given in table (1). three steps are performed in the present work toward designing an active vibration control to the cantilever beam. in the first step, the natural frequencies for derived mathematical model of th beam equation (30) are calculated and compared with the natural frequencies obtained from the ansys program. the results are presented in table (2) which show a good agreement. this proves that the derived model represents system dynamics at least with respect to the dominant natural frequencies. also the balance realization and order reduction process for the system model had been performed to reduce its states from twenty-four states to three states, without affecting its dominant mode. this is demonstrated in figure (2) in the bode plot. table 1, physical and geometrical specification for flexible cantilever beam and the piezoelectric physical specification cantilever beam piezoelectric length l=276 mm la =46 mm width b =33 mm b= 33 mm thickness tb =1 mm ta = 0.762 mm young modulus eb =193.06 gpa ep = 68 gpa density ρb =8030 kg/m 3 ρp = 7700 kg/m damping coefficients α = 0.8 & β = 6.8e-5 table 2. natural frequency results of the system natural frequency matlab (hz) ansys (hz) % f1 11.878 11.421 3. f2 61.376 61.148 0.37 f3 181.06 180.1 0.5 al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 59 simulation results and discussion the simulation results for a cantilever beam, subjected to an initial tip deflection, are presented in this section where the matlab 14 the cantilever beam system. the physical and geometrical specifications for the beam are given in table (1). three steps are performed in the present work toward designing an active vibration control to the cantilever beam. in the first step, the natural mathematical model of the ) are calculated and compared with the natural frequencies obtained from the ansys program. the results are presented in table (2) which show a good agreement. this represents the th respect to the also the balance realization and order reduction process for the system model had been performed four states to three states, without affecting its dominant mode. in the bode and geometrical specification for the flexible cantilever beam and the piezoelectric. piezoelectric 46 mm = 33 mm 0.762 mm 68 gpa = 7700 kg/m 3 %error 3.847 0.371 0.530 fig. 2. bode plot. in the second step, the sliding mode observer is designed to the reduced order model. the dimension of the rm for the smo is selected in this work equal to six while the lqr control will use only three of them. the idea behind this step is that the estimation error is decreased by using larger dimension to the reduced order model than that used in the control law. the estimated output using the smo states (� � tg�g, �g is the estimated six states) is compared with actual output in the discontinuous term injected equation (53) with ´ � 130000 output is chatters around the actual piezoelectric output. this is more clarified in figure the error between the actual output and the estimated output equations ( plotted. the chattering effect can be removed by replacing the signum function eq a continuous approximate function (the arc tan function). the signum function µ��¶q³· è �é ∗ tanq�� � ∗ q³� , replacing µ���q³� by the approximation given above will prevent chattering and give smooth values for the estimated states shown in fig to 6). by using only three of the estimated states, the designed control law based on the is applied to the cantilever beam dynamic and the system is simulated for 15 mm initial tip displacement. the system eigenvalues after using the proposed lqr control are found in table (3). table (4) shows that by using reduced model of dimension three, four or six that can be selected according to the singular values, the control lqr change the value of the minimum absolute eigenvalue to the same value. so the best choice of the reduce model dimension is three. khwarizmi engineering journal, vol. 13, no. 1, p.p. 5065(2017) 2. bode plot. in the second step, the sliding mode observer is designed to the reduced order model. the dimension of the rm for the smo is selected in this work equal to six while the lqr control will use only three of them. the idea behind this step ion error is decreased by using larger dimension to the reduced order model than the estimated output using the smo states is the estimated six states) is compared with actual output in figure (3). due to in the smo (² in 130000)), the estimated output is chatters around the actual piezoelectric . this is more clarified in figure (4) where actual output and the (46) & (51)) is plotted. the chattering effect can be removed by function equation (54) with a continuous approximate function (the arc tan function is replaced by; � � 0.1 by the approximation given above will prevent chattering and give smooth values for the estimated states shown in figures (5 by using only three of the estimated states, the designed control law based on the lqr approach is applied to the cantilever beam dynamic and the system is simulated for 15 mm initial tip displacement. the system eigenvalues after using the proposed lqr control are found in table (3). (4) shows that by using reduced model of sion three, four or six that can be selected according to the singular values, the control lqr change the value of the minimum absolute eigenvalue to the same value. so the best choice of the reduce model dimension is three. shibly a. al-samarraie al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 5065(2017) 60 fig. 3. the actual and the smo sensor output. fig. 4. the error between the actual and the estimated sensor output. fig. 5. the error between the actual and the estimated sensor output (with removing chattering). fig. 6. the actual piezoelectric sensor output and the smo output (with removing chattering). table 3, open and closed loop system eigenvalues. system eigenvalues (open loop) new system eigenvalues (closed loop) -0.58936 + 74.626i -1.5686 + 74.863i -0.58936 74.626i -1.5686 74.863i the first set of numerical simulation to the control system and the smo uses a 0.00001 second as a period of integration and with the approximate signum function in the observer design as defined above. in figure (7) the controlled tip displacement with the actual system output is compared, the ability of the controller in stabilizing the tip displacement is clarified in this figure where it required about 3 second only. in addition, the control input voltage to the piezoelectric element is plotted in figure (8), where, as can be seen, the control input is saturated to the maximum value 200v which is the maximum design value to the piezoelectric voltage. table 4, open and closed loop minimum absolute eigenvalues. in order to approach the real situation, the time period for the observer is taken equal to 0.0001 second (i.e., the change in the estimated six states happened after each 0.0001 second), while 0.0025 second is the chosen time period where the control input changes. consequently, the second set of numerical simulation is based on these time numerical values for both; the observer simulation period of time and for the time period required for the control input voltage to change while the time period for the control system simulation is still equal to 0.0001 second. figure (9) plots the actual output and the estimated output with time. the effectiveness of the smo can be detected from this figure where the idea is to force the estimated output to follow the actual one in a short time. after that, the estimated states will be used in the control law equation (42) which will attenuate the beam vibration. the tip displacement of the open and closed loop are plotted with time in figure (10), additionally, the control input voltage is shown in figure (11), where, as can be seen, the vibration suppression ability is nearly the same as in the first set of simulation. this enhance the applicability of the proposed controller. reduced model q êë (open loop) êì (closed loop) max control input voltage 3 20* [ 50 50 1 ] 0.5893 1.5686 320 4 20* [ 50 50 1 1 ] 1.2979 340 6 20* [ 50 50 1 1 1 1 ] 1.3073 350 shibly a. al-samarraie al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 5065(2017) 61 fig. 7. tip displacement for open and closed loop control system. fig. 8. the control input voltage to the piezoelectric actuator. fig. 9. the actual and the smo sensor output. fig. 10. tip displacement for open and closed loop control system. fig. 11. the control input voltage to the piezoelectric actuator. 7. experimental setup and results the beam used in the current analysis was a stainless steel of length 276 mm, width 33 mm, and thickness 1 mm. two piezoelectric (pzt) patches (type qp20w), of dimensions 46×33 mm and thickness 0.762 mm, were used as sensor and actuator, as depicted in figure (1). the parameters of the flexible beam and pzt patches are given in table (1). the control objective is to show the effectiveness of the designed lqr controller, via the sliding mode observer, to suppress the vibration of the smart cantilever beam by means of piezoelectric elements. to achieve this control objective an experiment is set up. the experimental set up is depicted in figure (12), which consists of a stainless beam, two pzt patches (bonded on two sides of the beam at the location indicated), accelerometer (adxl335), two data acquisition systems (ni-pci 6036 and ni-usb 6259), high voltage power amplifier (trek601b-3), and a pc to control the system via labview program. the beam is initially excited by 15mm tip displacement, as the beam vibrate, the stress induced in the pzt patches will generate voltages proportional to these stresses, in this case one pzt patches is working as a sensor. as the voltage signal sent to the data acquisition, type ni-6036e, the labview program, designed for this purpose using sliding mode observer, will use these signals to observe the states of the system and then fed-back to the controller. the control signals are sent to the data acquisition and then to high voltage power amplifier, type trek-601b-3 to apply this action to the other pzt element, in this case the other pzt is used as an actuator. as a result, the vibration in the beam will be suppressed. the controller system sent signals between ±5 volt, then these signals are amplified 40 times, by power amplifier, therefore the control signals are bounded within ±200 volt. the tip point displacement of the beam was measured by using the accelerometer, as shown in figure (12). the measured signals are sent to the data acquisition type ni-6259, and then to the pc computer to the control algorithm programmed in the labview software. the acceleration signals were converted to displacement by double integral, and then plotted with time. shibly a. al-samarraie al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 5065(2017) 62 power amplifier trek-601b-3 ni-pci 6036 data acquisition ni-usb 6259 data acquisition piezoelectric actuator piezoelectric sensor beam accelerometer (a) (b) fig. 12. experimental set up of the flexible beam system; (a) schematic diagram, (b) hardware set up. the controlled and uncontrolled tip displacement are plotted in figure (13). it can be seen that the current control action is having the ability to suppress the tip displacement within 3 second. the pzt patch sensor output (the actual output) and the sliding mode observer output are given in figure (14), while the voltage inputs to pzt patch actuator is shown in figure (15). finally, a good agreement are clear between the experimental results see figures (13 to 15) and the results obtained from the numerical simulations figures (9 to 11). fig. 13. experimental tip displacement for open loop and closed loop control system. fig. 14. the actual piezoelectric output and the smo output. fig. 15. experimental input voltage. 8. conclusions in this paper, the state space model is obtained using the finite element approach and the modal analysis resulting after appropriate modal reduction. during the theoretical calculations, the 24 th order system model obtained from the finite element model is reduced to the three order using a model reduction technique based on balance realization without affecting its dominant modes. as a basic requirement to the control design, the sliding mode observer is designed to estimates six states of the reduced model. in spite of the presence of the unknown inputs, which due to the residual model in the observer dynamics, the smo forces the output, which is determined from the estimated states, to follow the actual output. this is taken place after approximately two seconds. after that, the reduced model states are estimated with bounded error. to overcome the chattering problem in observer dynamics the signum function is replaced with the approximation given by the arctan function with appropriate parameters. as a result, the chattering is prevented and the estimated states values become more smooth. using the estimated states, an lqr approach was designed based on the reduced order model. the control spillover was avoided by satisfying the avoidance condition where the minimum absolute real eigenvalue is three times to that for -15 -10 -5 0 5 10 15 0 2 4 6 8 time (sec) without control with control t ip d is p la ce m e n t (m m ) -3 -1.5 0 1.5 3 0 2 4 6 8 time (sec) actual output estimated output o u tp u t , y , y o ( v o lt ) -200 -100 0 100 200 0 2 4 6 8 time (sec) u ( v o lt ) shibly a. al-samarraie al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 5065(2017) 63 the matrix � equation (30). with the proposed lqr control and the smo, the results show that for 15 mm initial tip displacement, the piezoelectric actuator reduces the tip displacement to about 0.1 mm during 3 s. the performance of the designed controller is examined experimentally where the results are shown very satisfactory and very close to the theoretical analysis. notation a* cross-section area of the beam element (mm 2 ). �^ cross-section area of the piezoelectric element, (mm2). � state matrix. h width of the beam (mm). s input matrix. � constant which equal to í?@ 12 t output matrix. .�� piezoelectric constant. q�� piezoelectric stress/charge constant. �* young modulus of the beam (gpa). �f young modulus of the piezoelectric (gpa). dn� external force (,). d[ g/ control force (,). e�, e� force acting at the node (,). z[ signal condition device. ℎ constant vector. o��� sensor current. î* stiffness matrix of the beam element (,/)). îf stiffness matrix of the piezoelectric element ( ,/)). #* length of the beam element (mm). ± length of beam (mm). )* mass matrix of the beam element. )f mass matrix of the piezoelectric element. , shape function. b vector displacement. velocity vector. bc acceleration vector. �~ minimum absolute real eigenvalue �| minimum absolute real eigenvalue �j thickness of the actuator, (mm). �* thickness of the beam,(mm). ® kinetic energy ( ,.)). r control input (volt) � strain energy (,.)). uj actuator voltage (volt). uv sensor voltage (volt). ���, ��displacement function. � degree of freedom. k , l damping coefficient. ï strain. �* density of the beam ( >�/ð�). �f density of the piezoelectric patch (>�/ð�). 9. references [1] mehmet, i. metin u.s.; 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[41] moor, j.b.: optimal control linear qardatic methods, usa: prenticehall (1989). � ا�� ا ����ا�� ��� � ا ��ارز�� ا �� ��� ا ��� �� 1، ا � د13�� ،65-50 )2017( 65 ا/ھ#(ازات �#�� ا &�$� �� ا ,+�� �* ا ��� ا ��( ) ا '&% $��#� ام ا!�� � ا ��اد ���0 ا &��و��123 � �� �7ري ��(ة* ا�� ا ����ا����� *** ا �9�8�: ���***:��د :� ا ا"3456* ا"12!0"0/)*/ .(� ھ!,+* ا"()'&ة وا"! � * ا"3456* ا"12!0"0/)*/ .(� ا":!,+* ا"9)851)1)* *** ، ** uotechnology.edu.iq6013@2: ا"<&=, ا>"21&و8;* dr.mohsin@uotechnology.edu.iq: ا"<&=, ا>"21&و8;** emad099@yahoo.com: ا"<&=, ا>"21&و8;*** ا �;�� 9(9?@ ab>"ا اcم ھ,e=5 " ام,f2+5g *h@58 *i5رk ;l ازn259د ا>ھp9()'& إr4 r(!sوا"09اد ا"1:& ا*('ti .u?" �@ &:1"وا"09اد ا vwk *('ti x'+ ytz4 [932" *i1) ا"53ر(( 45)851actuator ())b245و . r4 ھ!5ك 4?,ران &(s^@ 59ا"23<*، وھ ;l ار&e2+<م ا,k5ت(k5ت ا"()'&ة @,ا(kا,@ &(s^@و r9f9"ا "2?9)� 8 5م . ا"! 5م اr4;wij 098ذج eff4 اg! & ا>2k<5ر l; ا"2?9)� ا"5b"; "! 5م ا"()'&ة vwk أ+5س ھr=c ا"9?,ر=b5>9 r&ة، a(a @� اcp ا"`)& *e=&ام ط,f2+ا �از، @n2ا>ھ l(ff@ m8^b r4 يc"وا �1b@)balance realization ( 2)5رp<ا vwk *(wg5. &opا ا"!09ذج أc01ن ھ= a(a eًff4 098ذج r(9f2"ا"()'&ة وا .;wijا"! 5م ا rk eff9"09ذج ا!w" ات&(t24 *sys 5ر(2pا �@. u"n!9"ا r9f9"ان 8 5م ا v"ف إ,:= ،sl519"ا"9()'& ا vwk ,!2)= يc"وا ، m@5>sإ �59 @p د,b4 ,(9f2"ا ;l ^'f"إن ا a(a ات&(t24 *2+ &=,e@ . �1b@ ة,aو �9)?@ �@ ،u"n!9"ا r9f9"ا u=&ط rk ات&(t29"ا r(9f@ ام,f2+5glqr "s^@ *w1z4 vwk uwt2w)& ا"()'&ة `)& ا"b5>9&ة، @� ا5e2bق b&ط و. ti';واb r4 [o4j^5:8 أن @r4 lff اھn2از ا"23<* ا"pc)* وf2+5g,ام ا"3!?& ا"1:& f2+5g,ام ا"5p5b9ة ا"3,د=* @� ا2p<5ر .,رة 8 5م .@u(eb ا>+e2&ار=* وا"cي =r9w ا+e2&ار ا"2w" &'()9?9)� ا"2e9&ح وا"cي +)we] ا>ھn2از l; ا"23<* ti')* .5در we@ vwk)] و59دة ا"4w"&:1�a ،)} و/, 5gن ا"tz9] ا"9)851)1; ١٥ا"23<* @� ازاa* ط&ف 59p . هو@9f), ا"()'&ة ا"2e9&ح "we2)] ا>ھn2از ا"!��52 ا"vwk *(w93 ا"23<* ا"pc)* اjداء ا"085e" n(929ن ا"()'&ة اظ:&ت . w4� l; ا"5b"* ا"b&ة r(a ;l ،*(85s١.٥ أن .)5:29 w4٤� 3g, ٠.١ا>زاa* إ"0a vا"; &2e9"1] اz"ا u"n!4 &'()9"حوا. (microsoft word \307\323\321\307\301 \332\341\355 \337\307\331\34329 37) al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 15, no. 3, sptember , (2019) p. p. 2937 optimizing the parameters of hot-wire cnc machine to enhance the cutting of plastic foam israa q. mohammed* ali h. kadhum** *,**department of automated manufacturing engineering/ al-khwarizmi engineering college/ university of baghdad * email: israaqm.90@gmail.com **email: kadhumali59@yahoo.com (received 23 october 2018; accepted 28 january 2019) https://doi.org/10.22153/kej.2019.01.006 abstract hot-wire cutting is one of the important, non-traditional thermomechanical way to cut polymer, usually expanded foam and extruded foam, in low volume manufacturing. the study and analysis of hot-wire cutting parameters play an important role to enhance the quality and accuracy of the process and products. the effects on the surface have been investigated by using experimental tests designed according to the taguchi orthogonal array (oa). in this study, four parameters with five levels for each parameter have been used: [temperature of wire (a) (100, 120, 130, 150, 160) °c], [diameter of wire (b) (0.3,0.4,0.5,0.7,0.8) mm], [velocity of cutting (c) (200, 300،400,500,600) mm/min], [and density of foam (d) (0.01,0.027,0.029,0.032,0.037) g/cm3]. statistical software (minitab17) used to find the optimum conditions, which they are in material removal: 100 ˚c, 0.5 mm, 300mm/min, 0.032 g/cm3. keywords: hot-wire cutting, polystyrene, foam cutting, taguchi, minitab1, material removal. 1. introduction today the products of plastic are an important and integral part of everything in our life. the process of manufacturing the plastic foam is the casting and extruding, so the perfect way to cut these types of foam is hotwire cutting. this cutting can be performed with a source of heat, which is wire that change the physical properties of material until it can be cut with low cutting force [1]. there are several mechanisms for the cutting of plastic foam; they can be divided into three-basic modes or the mixing among them: • thermal cutting: in this mode, the plastic foam is vaporized or just melting in front of the wire cutter but without touching between them. see figure 1.a. • thermo-mechanical cutting: this mode is a mixing between the shearing force and the melting of material to perfume the cutting and the hot-tool in contact with the material. see figure 1.b. mechanical cutting: this mode depends on the shearing because it happens when the temperature of tool is below the melting point of the foam [2]. as shown in figure 1.c fig. 1. cutting mechanism [2]. simply the principle work is an electrical power pass through wire then the wire is heated to desired israa q. mohammed al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 2937 (2019) 30 temperature degree according to the input voltage through electrical resistance. when the wire contact the surface of foam, it melts the area surrounding it, the heat of the wire vaporises the foam creating a smooth surface figure 2. shows the wire is moving across the specimen of foam material. fig. 2. the hot-wire foam cutter. the material to be cut is just soften under the point of melting because it is thermoplastic material, after that the cutting is done. the surface of the cut and kerf-width is affected by the changing of the velocity and the diameter of wire even if it was small [1]. many researchers have studied the cutting process of polymers and the effective parameters on it. harmanpreet & manpreet singh [3] studied the effect of parameters for the polymer cutting process on material removal rate and kerfwidth also the optimization of the machining process. ranjeet et al [4] maked investigation in ablation process for the expanded polystyrene (eps) rapid prototyping to predict and calculate the kerfwidth and surface roughness (ra) with mathematical model. kiril & jesper [5] proposed a novel thermoelectro-mechanical model for hotwire cutting of eps foam and predicts the stress, voltage and temperature of wire during cutting of eps foam. in addition, find relation between kerfwidth and the cutting angle as measured from the horizontal direction. namrata & sathyan [6] investigated the factors responsible for the bowing phenomenon via a series of experiments involving variations in current and wire feed rate, build more precise prototypes, kerf width is also examined, further more finding noval way to predict the influence of gases in bowing has been analyzed and quantified. luka ivanovskis [7] developed a 4-axis numerically controlled hot-wire foam cutter suitable for flying aircraft modelling purposes. numerically controlled foam cutter had to be able to cut intricate shapes out of foam material such as extruded polystyrene by using 3d virtual model, also find novel mathematical model to predict the kerfwidth, and empirical relationship is established to predict the surface roughness (ra) of the sliced surface by performing regression analysis. ahn et al [8] studied the influence of process parameters on the surface jroughness in hotwire of variable lamination manufacturing (vlm-s) for eps foam such as cutting angle and compositions of expandable polystyrene eps, the apparatus is fouraxis automatic cutter and the specimen is thin foam. while in my study, parameters differsand the device is 2d axis cnc. with any thickness of foam can be cut. p. gallina et al [9] studied the hot wire with 2d robotic system to cut polystyrene plates with accurate force control which is delayed reference control (drc) with time delay: ��(tt) ,t the time delay calculated online, while my study is about 2d cnc machine and different parameters to reach optimum conditions of cutting without considering of time. the objective of this paper is to obtain the optimum cutting conditions for hotwire cutting process, and study the effects of these parameters on the process. 2. material and method 2.1 foam used in hotwire cutting extruded polystyrene (xps) foam is used in this study with different densities. foam is a combination of polymer solid phase and gas mixed together in high speed until it become as smooth as desired. the applications are virtually endless, ranging from items as small as a kitchen sponge to a soundproofing systems in cinemas [10]. 2.2 implementation of parts of the machine the machine is very easily adjustable and therefore it is expected to provide a possibility for high accuracy, with specifications as shown in table 1. the two stepper motors as shown in figure 3 make together the movements of the two axes x and y, which are vertically and horizontally standing. the motors velocity of hotwire cnc machine adjusted by the universal g code sender software (which is platform of g-code with full featured used to interface between motors of cnc and the computer) as shown in figure4, through the arduino-uno shown in figure5 [11]. israa q. mohammed al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 2937 (2019) 31 table 1, specifications of cnc machine no. of cnc axes 2 a xis motors stepper 1.8° , 2a ,12 v cutting bow width 170 mm, height 350 mm fig. 3. the two axis of cnc. the cutter consists of an elbow of aluminium insulated by small ceramic cylinders on both ends to avoid short circuit, and the wire of cut which is nichrome (nickel-chromium alloy). fig. 4. screenshot of the gcode universal. fig. 5. arduino and cnc shield. 3. hot-wire process parameters 3.1 temperature of wire the five levels of temperature are (100,120,130,150,160) °c which can be adjusted by tunning the power supply. the infrared thermo camera flir t335 used to ensure the temperature of wire as shown in figure 6. fig. 6. infrared thermos camera flir t335. 3.2 cutting velocity of the process: the velocity levels are (200, 300, 400, 500, and 600) mm / min can be adjusted through the universal g code sender software. 3.3 the diameter of wire the available diameters in the market are:(0.3,0.4,0.5,0.7,0.8) mm. 3.4 the density of foams the material of workpiece is xps foam with different colours and densities (purple 0.037, yellow 0.032, blue0.029, pink 0.027 and white 0.01 g/cm3) as shown in figure 7 to recognize each one according to the density. fig. 7. foam colours. israa q. mohammed al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 2937 (2019) 32 4. optimizing parameter with minitab17 and taguchi technique the minitab17 is statistical software using taguchi method which is technique used to find the optimum values for the parameters and minimize the number of experiments that have to be done. optimization of process parameters is done to make a great control to the process, it is effective way to improve quality of product at a relatively low cost. in this study taguchi minimized the total experiments from 625 to 25 effective experiments in orthogonal array as shown in table 2. this orthogonal array has 25 rows and 4 columns, each columns represents specific process parameters while each row represents a trial condition [12,13]. table 2, the orthogonal array of taguchi table 3, the orthogonal array of taguchi uncoded no. a (temp.) b (diameter) c (velocity) d (density) 1 100 0.3 200 0.01 2 100 0.4 300 0.027 3 100 0.5 400 0.029 4 100 0.7 500 0.032 5 100 0.8 600 0.037 6 120 0.3 300 0.029 7 120 0.4 400 0.032 8 120 0.5 500 0.037 9 120 0.7 600 0.01 10 120 0.8 200 0.027 11 130 0.3 400 0.037 12 130 0.4 500 0.01 13 130 0.5 600 0.027 14 130 0.7 200 0.029 15 130 0.8 300 0.032 16 150 0.3 500 0.027 17 150 0.4 600 0.029 18 150 0.5 200 0.032 19 150 0.7 300 0.037 20 150 0.8 400 0.01 21 160 0.3 600 0.032 22 160 0.4 200 0.037 23 160 0.5 300 0.01 24 160 0.7 400 0.027 25 160 0.8 500 0.029 the foam cutting process can be outlined as the following steps, which describe the whole process done by the machine and then the results can be processed with the minitab software. 1. fix the hotwire cutting cnc on the table 2. fix the foam with in the proper place by fixtures. 3. turn on the power to the wire, wait until reach to the required temperature of wire, that can be ensured by the infrared camera 4. turn on the dc power supply of the shield, then give the order (gcode of the required shape) to the motors to move, to cut by the arduino program (universal gcode sender), with the velocity that given. no. a code b code c code d code 1 1 1 1 1 2 1 2 2 2 3 1 3 3 3 4 1 4 4 4 5 1 5 5 5 6 2 1 2 3 7 2 2 3 4 8 2 3 4 5 9 2 4 5 1 10 2 5 1 2 11 3 1 3 5 12 3 2 4 1 13 3 3 5 2 14 3 4 1 3 15 3 5 2 4 16 4 1 4 2 17 4 2 5 3 18 4 3 1 4 19 4 4 2 5 20 4 5 3 1 21 5 1 5 4 22 5 2 1 5 23 5 3 2 1 24 5 4 3 2 25 5 5 4 3 israa q. mohammed al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 2937 (2019) 33 5. wait until finishing the cut 6. take the part to make measurements. 7. find the material removal mr of the cutting pieces by comparing between the weight before and after the cutting process by using delicate balance. 8. repeat all steps with changing the parameters according to the tagauchi array of 25 experiments. 9. enter the factors (inputs) and results(outputs) in the minitab program to find optimization. 5. results and discussion the results have been analysed by using (miniitab17) in the following steps: 5.1 signal to noise ratio (s/n) the (s/n) ratio is defined as standard approach where the result used for the average of the result is run with the main parameter. the optimum with s/n ratio is studying, the main effect of the parameters and giving the optimum result which effect on the process. in the hotwire cutting process, the s/n ratio is used to measure the sensitivity of the quality surface characteristic with the parameters [14]. there are three categories of the quality characteristics: smaller is better, normal is better and larger is better, the aim of any experiment is always to determine the highest possible (s/n) for the result. in this study selecting the smaller is better which means the maximum response of the material removal with the smallest lost of material [15]. the mean squared deviation (msd), (s/n) ratio and prediction are determined by the equations (smaller is better) below: msd=( � � � (y � ��� … (1) (s/n)ratio=10 log10 ( � � � (y � ��� ) … (2) where: n: is the number of the trial i: is trial number the analysis of material removal is explained with the parameters by using (s/n) ratio, describes the quality of the surface in the hotwire cutting process. the results have been analysed by using s/n ratio to obtain the optimal level for each process parameter that has larger effect of the surface quality. the main effect of each parameter with four level on the s/n ratio and mean for material removal are calculated in the tables (3&4), the plot of the s/n ratio and mean is shown in the figure (8&9). note: there are 4 experiments failed through cutting, so they neglected in all calculations. table 4, the main effect of the s/n ratio for mr s/n ratio for response level a b c d level 1 59.21 48.98 46.19 44.26 1 2 41.81 45.20 46.35 44.26 2 3 43.37 51.21 45.38 38.99 3 4 45.29 37.76 44.05 45.25 4 5 45.99 45.84 45.63 39.96 5 delta 17.39 13.46 2.30 17.17 delta rank 1 3 4 2 rank s/n ratio optimization table 5, the main effect of the mean for mr means for response level a b c d 1 0.001700 0.005620 0.007940 0.002860 2 0.008225 0.006120 0.007020 0.007160 3 0.008020 0.003767 0.007750 0.011575 4 0.007120 0.013275 0.007133 0.005975 5 0.007800 0.006975 0.005950 0.010233 delta 0.006525 0.009508 0.001990 0.008715 rank 3 1 4 2 mean optimization from the tables (3 and 4), the effect of each factor (rank) can be seen which mean the effect degree of each factor on the mr. in addition, the optimal level of the parameters with mr is calculated according to the larger value of the mean and s/n ratio, so in this case the rank of optimal parameters which effected on the mr is: wire temperature (a), followed by density (d), then the wire diameter(b) and velocity of cut (c) , and it noticed that the optimal condition is : a1 , b3 , c2 , d4 for s/n ratio, and a2, b4 , c1 , d3 for means . figures ( 8&9) show the plots of sn ratio and mean of the mr for the material. israa q. mohammed al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 2937 (2019) 34 fig. 8. main effects plot s/n ratio plot for mr. fig. 9. main effects plot of means for mr. for this situation, we need to make a prediction. this can be used to predict the optimum level of s/n ratio and mean, then choosing the optimum level which depends on the large value of the s/n ratio [ 16] as shown in table 8. table 6, the prediction of the mean and s/n ratio of mr s/n ratio mean a b c d a b c d 1 3 2 4 2 4 1 3 s/n ratio mean s/n ratio mean 63.3489 -0.00066 38.4977 0.01147 from the table 5 the optimum predict value for s/n ratio is 63.3489 which is the larger, that mean in the conditions of: a1(100 c), b3(0.5mm), c2(300mm/min), d4(0.032 gm/cm3) the material removal is in the smallest removed amount which is the optimum result. 5.2 analysis of the variance (anova) the optimum of the work accomplished by determine the percentage of each parameter on the results of the experiments. the anova is a statistical treatment analysis which is used for this purpose for the mr [16]. in this part, anova is used to determine the influence of the parameters on the material removal as shown in the table 6. israa q. mohammed al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 2937 (2019) 35 table 7, anova for mr source df adj ss f-value p-value contributed (%) temp. a 4 0.000033 0.65 0.655 3.4 diameter b 4 0.000160 8.58 0.030 46.8 velocity c 4 0.000039 1.04 0.484 5.5 density d 4 0.000136 7.04 0.043 38.6 error 4 0.000038 5.5 total 20 0.000406 100 from table 6, it is noticed that the significant effect of the parameter is the diameter (b 46.8%) then the density (d 38.6%) followed by the velocity (c 5.5%), and temperature (a 3.4%) as shown in figure 10. fig. 10. the contributed percentage of the factor for mr. 5.3 regression equations for mr regression is a statistical measure used to find and calculate the mathematical relationship between the independent variables and the dependant variables or in other word the input and output parameters which is linear [17]. the general form of multiple regression is: = � + ���� + � � + ���� + ⋯ + ���� … (3) t = 1,2,3, ……n while: y: the output or the predicted variable x: the input or the variable which is needed to find y value a: constant b: slope by using minitab software, the regression equation for estimating the mr used to find the comparison between the experimentally and numerically results of them, that has been obtained as the following: y= 0.00551+0.01008b + 0.2759 d ... (4) where: b: the wire diameter d: the density of foam y: material removal 6. conclusions from analysing the results of experiments, which they are physical and mechanical tests by using minitab17 we obtained some conclusions and summarized as: 1. the signal to noise ratio (s/n) for hotwire cutting process, found that: the optimum condition for mr are: the temperature is 100˚c, diameter of wire is 0.5 mm, velocity of cut is 300mm/min and density of foam is 0.032 gm/cm3. 2. this research agreed with the previous researches, that the diameter of wire b has larger percent of effect on the mr (46.8%), (because increasing the diameter cause to increase the mr), followed by the density of foam d (38.6%),(because of increasing the shear force), then the velocity of cutting c (5.8%), and temperature of wire a (3.4%) , because the melting of materials. fig. 10 show the plot of the material that, increasing the diameter cause to increase mr. 7. aknowledgment thanks a lot to god who helped me and gave me the strength to complete this research. i would like to offer my thanks and appreciation to my supervisors al-khwarizmi college of engineering for continual inspiration and gave me all support during the research period. thanks to my family that i always find beside me to give full support in my life. special thanks are due to my husband who was the source of my power in the moments of weakness. finally, i would like to express my thanks to my friends and everyone who gave me any type of assistance throughout the course of research a b c d error category error 5.5% d 38.6% c 5.8% b 46.8% a 3.4% pie chart of mr israa q. mohammed al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 2937 (2019) 36 list of abbreviations anova analysis of variance cnc computer numerical control eps expanded polystyrene mr material removal oa orthogonal array ra surface roughness smps switched-mode power supply s/n signal to noise ratio xps extruded polystyrene 8. references [1] aitchison, d., brooks, h., bain., j., pons, d. “an investigation into the prediction of optimal machining conditions for polystyrene foam cut with a taut hot-wire”. the annals of “dunarea de jos” university of galati, fascicle v, technologies in machine building, issn 12214566, 2009 [2] h. brooks, “plastic foam cutting mechanics for rapid prototyping and manufacturing purposes” (ph.dthesis), mechanical engineeringat the university of canterbury , christ church , new zealand , 2009 [3] harmanpreet & manpreet singh, “influence on kerf width in machining polystyrene by heating element profile maker using nichrome wire”, international journal of engineering and technical research v4 (04), april 2015 [4] ranjeet k. b., sajan k., pushkar k. &k. p. karunakaran , “ investigation of ablation studies of eps pattern produced by rapid prototyping” ,virtual and physical prototyping, volume 13, issue 4, 2018. [5] kiril p.petkov, jesper h.hattel” a thermoelectro-mechanical simulation model for hot wire cutting of eps foam” international journal of machine tools and manufacture volume 107, pages 50-59,2016. [6] namrata karmakar , sathyan subbiah , “investigating bowing of hot wire during cutting of eps” procedia manufacturing volume 26, pages 671-680, 2018 [7] luka ivanovskis, “four axis hot-wire foam cutter controlled by mindstorms ev3 “, saimaa university of applied sciences, faculty of technology, lappeenranta degree programme in mechanical engineering and production technology, thesis 2017 [8] dong-gyu ahn, sang-ho lee, dongyol yang ,“influence of process parameters on the surface roughness in hotwire cutting of eps foam sheet for vlm-s rapid prototyping process”, journal of materials science 40(21):5699-5702, 2005 [9] p. gallina, r. mosca, p. pascutto, “optimized hotwire cutting robotic system for expandable polystyrene foam”, amst’05 advanced manufacturing systems and technology. cism international centre for mechanical sciences, vol 486. springer, vienna, 2005 [10] katrine sivertsen, polymer foams,3.063 polymer physics, spring2007 [11] https://libraries.io/github/winder/universalg-code-sender [12] r. k. roy,” aprimer on the taguchi method”,1st edition (new york: van nostrand reinhold ,1990) [13] balaraju.j, anup kumar.j, dayal saran.p, dr.c.s.krishna prasad rao"application of taguchi technique for identifying optimum surface roughness in cnc end milling process", international journal of engineering trends and technology (ijett), v21(2),103110 march 2015. [14] m.vishnu vardhan, g. sankaraiah, m. yohan , h. jeevan rao , ”optimization of parameters in cnc milling of p20 steel using response surface methodology and taguchi method” ,science direct ,volume 4, issue 8, , pages 9163-9169 ,2017. [15] shouvik ghosh, prasanta sahoo, and goutam sutradhar, “tribological performance optimization of al-7.5% sicp composites using the taguchi method and grey relational analysis”, journal of composites, volume, article id 274527, 2013 [16] hanan h. murad, “parametric investigation of the magnetic abrasive finishing method” (ms.c thesis), al-khwarizmi college of engineering of university of baghdad, 2017 [17] marwa k. qate’a, ali h. kadhum , faiz f. mustafa, “the influence of the magnetic abrasive finishing system for cylindrical surfaces on the surface roughness and mrr “ , al-khwarizmi engineering journal ,vol 11 no 3 , 2015 )2019( 2937، صفحة 3، العدد15دجلة الخوارزمي الهندسية المجلم اسراء قاسم محمد 37 إيجاد المثالية لمتغيرات عملية القطع بالسلك الحراري لتحسين خواص فوم البولسترين **علي حسين كاظم *اسراء قاسم محمد كلية الهندسة الخوارزمي / جامعة بغداد /قسم هندسة التصنيع المؤتمت **،* kadhumali59@yahoo.com :البريد االلكتروني* israaqm.90@gmail.com :البريد االلكتروني ** الخالصة الحرارية لقطع البوليمر عادة اما الفوم التمددي او الفوم االنبثاقي في اإلنتاج ذو ق غير التقليدية الميكانيكية ائالقطع بالسلك الكهربائي هو احدى الطر للمنتوجات. التأثيرات على السطح تم ودقتها م في تحسين جودة العمليةالدور المه ؤديالحجم القليل. الدراسة والتحليل لعوامل القطع بالسلك الحراري ت مستويات لكل متغير (حرارة ةطبقا الى مصفوفة تا كوشي. في هذه الدراسة تم استخدام أربعة متغيرات مع خمس ايجادها باستخدام تصميم التجارب العملية ) ٦٠٠ ٥٠٠ ٤٠٠ ٣٠٠ ٢٠٠ mm/min) و(سرعه القطعmm 0.3,0.4,0.5,0.7,0.8و(قطرالسلك )١٠٠،١٢٠،١٣٠،١٥٠،١٦٠ c° السلك على وفق لظروف القطع وكانت نتيجتها ةاليجاد المثالي 17minitab وتم استخدام برنامج )3g/cm0.01,0.027,0.029,0.032,0.037 ةو(كثاف :النحو االتي 3g/cm 0.032mm/min, 300 mm, 0.5c, ˚100 : mr .وكذلك نسبه تأثير كل عامل على العملية تم ايجادها 26 al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 4, no. 4, pp 26-36 (2008) effect of chloride ions on the corrosion behavior of al – zn alloy in naoh solution at four different temperatures rana a. majed , hanaa a. al-kaisy and hind b. al-atrakchy department of materials engineering/ university of technology (received 5 september 2007; accepted 13 may 2008) abstract this research involves study effect of chloride ions in concentration range (0.01 – 0.50 mol.dm-3) on the corrosion behavior of al-zn alloy in basic media of 1x10-3 mol.dm-3 naoh at ph=11 and four different temperatures in the range (298-313 k). cathodic and anodic tafel slopes (bc &ba) and transfer coefficients (αc & αa) were calculated and the results interprets according to the variation of the rate – determining steps. the results also indicate that the chloride ions are bonded chemically in the interface as an initial step of formation of different mixed oxohydroxy – and chloro complexes. polarization resistance (rp) is calculates and interprets the different polarization behavior because of addition of chloride ions to the basic media. keywords: al-zn alloy, effect of chloride ion, corrosion behavior in basic medium. 1. introduction: corrosion of aluminum has been a subject of numerous studies due to the importance of this material in contemporary civilization. it is well known that there is a potential region in which the rate of corrosion, even in such aggressive media as chlorides. the relatively complex corrosion mechanism of aluminium has been studies by several authors. corrosion of aluminium occurs only when the metal protective oxide layer is damaged and when the repair mechanism is prevented by chemical dissolution[1]. polarization methods have been extensively used to investigate the mechanism of localized corrosion and processes that lead to localized corrosion. in using potentiostatic techniques, the potential variable[2]. potentiostatic and potentiodynamic techniques have been applied by several authors to study the corrosion of aluminium in different environment[3-8]. the exceptional corrosion resistance of aluminium in many environments is due to its protective oxide film which is relatively inert chemically and so provides the passive behavior of aluminium. however in aggressive environments, particularly in the presence of halide ions, aluminium suffers from localized corrosion by local breakdown of the passive film. various theories are postulated to explain the mechanism of passivity breakdown in halide solutions but the most common and accepted ones are as follows: apenetration theory. bflaws and crack/heal theory. clocalized acidification theory. dcomplex formation theory. 2. experimental work: al – zn alloy was cut into cylinder shape with (1.2 cm) diameter, and made into electrode by pressing a copper wire into a hole on one side and then insulating all but one side with an epoxy resin. the open side was polished mechanically to a mirror finish, rinsed in distilled water and stored in a desiccator. the analytical composition of alloy was shown in table (1) which was obtained by chemical analysis in naser company. rana a. majed al-khwarizmi engineering journal, vol.4, no.4, pp 26-36 (2008) 27 table 1 the analytical compositions of al-zn alloy which useful in this search. metal zn mg cu cr ni ti mn al wt % 5.70 2.50 1.330 0.22 0.01 0.08 0.06 bal. the electrochemical glass cell was of the usual type with provision for working electrode (al-zn alloy), auxiliary electrode (pt electrode), and a luggin capillary for connection with an saturated calomel electrode (reference electrode sce). the basic solution was 1x10 -3 mol.dm -3 naoh (obtained by ferak with m.wt 40 g.mol -1 and purity >99.5%) and distilled water (specific conductivity 1x10 -6 s.m -1 ). to study the effect of chloride ions uses nacl (obtained by fluka with m.wt 58.44 g.mol -1 and purity 99.5%) was prepared with seven concentrations (0.01, 0.10, 0.15,0.20,0.25,0.35, and 0.50 mol.dm -3 ). electrochemical measurements were performed with a potentiostat (corroscript) which was obtained from tacussel (france) at a scan rate of 0.3 volt per minute. the tafel extrapolation and linearpolarization techniques are uses to determine the rate of corrosion. the tafel extrapolation method for determining corrosion rate was used by wagnar and traud to verify the mixed-potential theory, the method was shown in figure (1). tangents to the anodic and cathodic tafel regions were extrapolated to the point of intersection, from which both the corrosion potentials (ecorr) and corrosion current density (icorr) were determine using the four-point method [9] cathodic (bc) and anodic (ba) tafel slopes, transfer coefficients (α), polarization resistances (rp) together with other data could be derived from the polarization curves by using extrapolation method. fig.1. tafel extrapolation method. 3. results and discussion: figure (2) represent the polarization curve of al – zn alloy in 1x10 -3 naoh solution (ph=11) in the absence of chloride ions (cl¯) at 298 k, the section (abc) represented the cathodic polarization region which occur on the metals presumably by migration of electrons through the surface oxide films and subsequent interaction of those electrons with water molecules and dissolved oxygen at the film/solution interface, so the corrosion process is complicated with mass transfer. corrosion of al-zn alloy proceeds similarly by reduction of oxygen and the water molecules will act as the electron acceptor and the rate of corrosion is controlled by the diffusion limited current density for cathodic reduction, the probable reactions are: al 3+ + 3e → al o2 + 2h2o + 4e ↔ 4oh¯ h2o + e → 1/2 h2 + oh¯ thus metals like aluminium and zinc, whose oxides are amphoteric, are thermodynamically unstable in alkaline solutions and will react with water at high phs with consequent hydrogen evolution and formation of metal anions as shown below: al + 2h2o → alooh + 3/2 h2 along the section (cde), the metal hydroxide is expected to be formed. the hydroxide soon dissociates into metal oxide (al2o3) on a surface which behaves as a passive layer (protective film) according to the reaction: al 3+ + 3h2o → al2o3 + 6h + the breakdown of passivity began at point (e) and continued along (ef) and this section represent the anodic tafel region. the presence of cl¯ effects mainly on anodic polarization. fig. (3) show the effect addition of 0.01mol.dm -3 cl¯ on the corrosion behavior, since addition cl¯ with this concentration penetrates the passive layer but partially destroyed and shifts passive potential (epass) to more negative values and corrosion current density to lower values. noble ecorr active a p p li ed p o te n ti al ( e ) v o lt icorr log current density anodic curve cathodic curve linear polarization region rana a. majed al-khwarizmi engineering journal, vol.4, no.4, pp 26-36 (2008) 28 fig.2. polarization curve for corrosion of al-zn alloy in 1x10 -3 mol.dm -3 naoh solution in the absence of chloride ion at 298k. fig.3. polarization curve for corrosion of al-zn alloy in 1x10 -3 mol.dm -3 naoh solution in the presence of 0.01 mol.dm -3 chloride ion at 298k. current density (a.cm-2) p o te n ti a l (v o lt ) (s c e ) a b c d e f current density (a.cm-2) p o te n ti a l (v o lt ) (s c e ) a b c d e f rana a. majed al-khwarizmi engineering journal, vol.4, no.4, pp 26-36 (2008) 29 when add a higher concentration of chloride ion, the passive layer was breakdown and (icorr) value increases with increasing the concentration of cl¯ in solution as shown in figs.(4) to (9) where the polarization curve, in general, consist of the cathodic (abc) and anodic (cde) tafel regions. fig.4. polarization curve for corrosion of al-zn alloy in 1x10 -3 mol.dm -3 naoh solution in the presence of 0.10 mol.dm -3 chloride ion at 298k. fig.5. polarization curve for corrosion of al-zn alloy in 1x10 -3 mol.dm -3 naoh solution in the presence of 0.15 mol.dm -3 chloride ion at 298k. current density (a.cm-2) p o te n ti a l (v o lt ) (s c e ) a b c d e current density (a.cm-2) p o te n ti a l (v o lt ) (s c e ) a b c d e b a rana a. majed al-khwarizmi engineering journal, vol.4, no.4, pp 26-36 (2008) 30 fig.6. polarization curve for corrosion of al-zn alloy in 1x10 -3 mol.dm -3 naoh solution in the presence of 0.20 mol.dm -3 chloride ion at 298k. fig.7. polarization curve for corrosion of al-zn alloy in 1x10 -3 mol.dm -3 naoh solution in the presence of 0.25 mol.dm -3 chloride ion at 298k. current density (a.cm-2) p o te n ti a l (v o lt ) (s c e ) a b c d e current density (a.cm-2) p o te n ti a l (v o lt ) (s c e ) a b c d e rana a. majed al-khwarizmi engineering journal, vol.4, no.4, pp 26-36 (2008) 31 fig.8. polarization curve for corrosion of al-zn alloy in 1x10 -3 mol.dm -3 naoh solution in the presence of 0.35 mol.dm -3 chloride ion at 298k. fig.9. polarization curve for corrosion of al-zn alloy in 1x10 -3 mol.dm -3 naoh solution in the presence of 0.50 mol.dm -3 chloride ion at 298k. current density (a.cm-2) p o te n ti a l (v o lt ) (s c e ) a b c d e current density (a.cm-2) p o te n ti a l (v o lt ) (s c e ) a c d e b rana a. majed al-khwarizmi engineering journal, vol.4, no.4, pp 26-36 (2008) 32 when only hydroxide ions (oh¯) exists in solution (naoh without additive), aluminium hydroxide al(oh)3 will be formed and so repairing the passive film on the anode. moreover the electrolyte at the anode will be replenished again with (oh¯) by migration. but when cl¯ exists in solution (naoh with additive), then part of the current will be transported by these ions and since the anode products in alkaline chloride solution is still al(oh)3, therefore the concentration of chloride ions at the anode will be increased rapidly while the concentration of hydroxide ions decreases to values corresponding to ph values less than (7), solid al(oh)3 is still formed, but finally the electrolyte becomes so acid that it leads to the formation of soluble anode products rather than solids. this process leads to the breakdown of passivity, the reactions may be given by: al → al 3+ + 3e al + 3h2o ↔ al(oh)3 + 3h + under equilibrium condition the rates of production and consuming of protons will be equal. the proton can be consumed by direct reduction: 2h + + 2e ↔ h2 or by diffusion to the bulk solution: h + (anode) h + (bulk solution) the results of ecorr, icorr, bc, ba, αc, αa, rp, and io for al – zn alloy in the absence and presence of chloride ions in naoh solution at four different temperatures have been given in table (2). from deep analysis of the cathodic and anodic regions of the polarization curves, it was possible to derive data concerning: a the cathodic (bc) and anodic (ba) tafel slops. bthe cathodic (αc) and anodic (αa) transfer coefficients. values of (α) have been calculated from the corresponding values of the tafel slope (b) using the relation [10,11]: )1...( 303.2  bf rt  where: r: gas constant (8.314 j.mol -1 .k -1 ). t: temperature in kelvin scale. f: faraday constant (96500). cthe polarization resistance (rp) may be defined as [12,13, 14]: )2...( )(    di eed r corr p where e and ecorr are the applied corrosion potential (volt) respectively, i is the current density (a.cm -2 ). for small polarization, one may write approximation [13,14]: )3...( )(    corr corrcorr p i e di eed r where ecorr and icorr are the corrosion potential (v) and corrosion current density (a.cm -2 ). the ratio (ecorr/icorr) thus corresponds to the resistance of the metal/solution interface to charge-transfer reaction. it is also a measure of the resistance of the metal to corrosion in the solution in which the metal is immersed. for low-field polarization [15]: )4...(  ofi rt i  and )5...(  p ocorr corr r fi rt i e where η=e-ecorr and io is the equilibrium exchange current density (a.cm -2 ). the reaction resistance (rp), which mainly depends upon the equilibrium exchange current density (io) determines what may be termed the polarizability, i.e., what overpotential (η=e-ecorr) a particular current density needs or produces since: )6...( )( ocorr corrcorr p fi rt i e di eed di d r     the polarization resistance (rp) was also determined in another way from sterngeary equation [16,17,18], where: )7...( )(303.20           corrca ca i p ibb bb di de r diffusion rana a. majed al-khwarizmi engineering journal, vol.4, no.4, pp 26-36 (2008) 33 the values of rp have been calculated from equation (7), which is presented in table (2). the results of table (2) indicates that the lowest value of (b =0.026 or α=2.4) and the highest value is (b=0.120 or α=0.5). a cathodic tafel slope of 0.120 (or α=0.5) may be diagnostic of discharge-chemical desorption mechanism for hydrogen evolution reaction of the cathode in which the proton discharge is the rate-determining step. if chemical desorption is the ratedetermining step, the rate will then be independent on the overpotential since no charge transfer occur in such step and the rate becomes directly proportional to the concentration or the coverage (θ) of the adsorbed hydrogen atoms, and may occur at coverage ranging from very small values to almost full surface layer formation [19]. table 2 values of corrosion potential (ecorr), corrosion current density (icorr), cathodic and anodic tafel slopes (bc & ba), cathodic and anodic transfer coefficients (αc & αa), polarization resistance (rp), and equilibrium exchange current density (io) for corrosion of al-zn alloy in 1x10 -3 mol.dm -3 naoh solution in absence and presence of chloride ions at four different temperatures. medium (mol.dm -3 ) t (k) corrosion b (v.decade -1 ) α passivity rp/10 +4 io/10 -6 (a.cm -2 ) -ecorr (volt) icorr/10 -6 (a.cm -2 ) -bc +ba αc αa -epass (volt) ipass/10 -5 (a.cm -2 ) 1x10-3 naoh (ph=11) only 298 1.66 2.916 0.107 0.55 0.99 0.501 14.910 0.172 303 1.61 3.125 0.100 0.60 1.20 0.542 13.913 0.187 308 1.56 3.333 0.095 0.64 1.22 0.581 13.044 0.203 313 1.50 3.750 0.091 0.68 1.24 0.622 11.594 0.232 ph=11 + 0.01 cl¯ 298 1.44 0.416 0.061 0.97 1.21 0.063 104.52 0.024 303 1.39 0.500 0.058 1.04 1.24 0.071 86.956 0.034 308 1.36 0.541 0.052 1.17 1.28 0.088 80.366 0.033 313 1.33 0.625 0.042 1.45 1.30 0.010 69.565 0.002 ph=11 + 0.10 cl¯ 298 1.39 0.541 0.044 0.120 1.34 0.41 2.584 0.993 303 1.36 0.583 0.034 0.111 1.76 0.55 1.938 1.346 308 1.33 0.625 0.031 0.081 1.97 0.75 1.557 1.703 313 1.31 0.666 0.029 0.062 2.14 1.00 1.288 2.093 ph=11 + 0.15 cl¯ 298 1.38 0.541 0.054 0.115 1.09 0.51 2.949 0.870 303 1.33 0.583 0.047 0.100 1.27 0.60 2.381 1.096 308 1.32 0.708 0.029 0.071 2.11 0.86 1.262 2.101 313 1.31 0.958 0.026 0.051 2.38 1.21 0.780 3.454 ph=11 + 0.20 cl¯ 298 1.39 0.666 0.060 0.120 0.98 0.49 2.607 0.984 303 1.37 0.833 0.049 0.093 1.22 0.64 1.672 1.560 308 1.34 0.916 0.042 0.083 1.45 0.73 1.321 2.007 313 1.32 1.416 0.027 0.068 2.29 0.91 0.592 4.550 ph=11 + 0.25 cl¯ 298 1.39 1.458 0.055 0.100 1.07 0.59 1.056 2.429 303 1.38 2.000 0.049 0.096 1.22 0.62 0.704 3.706 308 1.34 2.083 0.045 0.049 1.35 1.24 0.488 5.426 313 1.33 2.500 0.031 0.036 2.00 1.72 0.289 9.321 ph=11 + 0.35 cl¯ 298 1.38 1.666 0.052 0.057 1.13 1.03 0.708 3.622 303 1.35 1.875 0.047 0.055 1.27 1.09 0.586 4.447 308 1.33 3.333 0.046 0.050 1.32 1.22 0.312 8.501 313 1.32 3.750 0.042 0.042 1.47 1.47 0.243 11.09 ph=11 + 0.50 cl¯ 298 1.39 1.875 0.065 0.091 0.91 0.65 0.878 2.923 303 1.38 2.242 0.058 0.081 1.03 0.74 0.654 2.988 308 1.37 3.513 0.051 0.058 1.19 1.05 0.335 7.911 313 1.36 4.445 0.043 0.037 1.44 1.67 0.194 13.88 rana a. majed al-khwarizmi engineering journal, vol.4, no.4, pp 26-36 (2008) 34 the expected tafel slope in such step would then be -0.03v.decade -1 (or =2.0). when electrochemical desorption becomes the rate-determining step for the hydrogen evolution reaction on the cathode, the expected value of bc is -0.05v.decade -1 (or α=1.5). the variation of the cathodic and anodic tafel slopes or transfer coefficients may be attributed to variation of the rate-determining step in the metals dissolution reaction. another approach to the problem of the electrochemical corrosion rate measurement is to apply only a small potential difference to the specimen and then measure the current density. the measurement of polarization resistance has very similar requirements to the measurement of full polarization curves and it is particularly useful as a method to rapid identifying corrosion, up-setting and initiating a remedial action[20]. the results of table (2) indicates that the values of rp which obtained for the solution at ph=11 and in the (ph=11+0.01 mol.dm -3 cl¯) system were higher than other media. generally, the polarization resistance (rp) in the other media decreases with increasing the concentration of chloride ion in solution because of increases the attack on the bare surface. the higher values of rp enhanced by presence the passive layer as shown in the polarization curves which attribute to produce aluminium hydroxide al(oh)3 which transform to protective film (al2o3) and reduces the expected attack on the surface alloy and lead to more resistance to corrosion as shown in fig.(2), and to the equilibrium states between al2o3 and alcl3 in addition to form al(oh)3 in (1x10 -3 naoh + 0.01cl¯) system as shown in fig.(3), but when add higher concentrations of cl¯ there are many soluble complexes to be form according to the following reactions: al + 3oh¯ → al(oh)3 + 3e al(oh)3 + oh¯ → al(oh)4¯ al(oh)4¯+ cl¯ → al(oh)3cl¯ + oh¯ al(oh)3cl¯+cl¯ → al(oh)2cl2¯ +oh¯ al(oh)2cl2¯+cl¯→ al(oh)cl3¯ + oh¯ al(oh)cl3¯ + cl¯ → alcl4¯ + oh¯ 4. conclusion: from the present measurements the conclusion indicates that the polarization behavior of al-zn alloy in 1x10 -3 mol.dm -3 naoh solution (ph=11) gives special case in the presence of 1x10 -2 mol.dm -3 cl¯ and this phenomena may be attributed to occur the equilibrium state between the al2o3 and alcl3 in addition to produce al(oh)3, while the addition of higher concentrations of cl¯ leads to increase the rate of corrosion of al-zn alloy in the basic media. chloride ion is bonded chemically in the interface as an initial step of the formation of different mixed oxohydroxoand chloro complexes according to the following formula[21]: al[ox(oh)y(h2o)z]+cl¯→ al[ox(oh)y-1 cl(h2o)z + oh¯ (alooh)4.h2o+ cl¯→ (alooh)3.alocl.h2o + oh¯ alooh + cl¯ → alocl + oh¯ al(oh)3 + cl¯ → al(oh)2cl + oh¯ finally the [alcl6] 3 complex is produced. the effect of cl¯ on the polarization curves be more significant in the anodic regions, where can be observe in figures (5), (6), and (8) anodic polarization observably is marked by two important regions, (a) and (b). the region (a) show a gradual increase in the current density with applied potential [22]. as soon as region (a) is crossed, a sharp rise in the current density is observed. this is characteristic of region (b). the break in the curve is due to the onset of pitting as consequence of breakdown of the oxide layer. but in figures (4), (7) and (9), decease this phenomena and the increasing in current density is sudden. 5. list of symbols: b tafel slope (v.decade-1) e potential (volt) f faraday constant (96500 c.mol-1) i current density (a.cm-2) r gas constant (8.314 j.mol-1.k-1) rp polarization resistance (ω.cm-2) t temperature (k) 6. greek letters: α transfer coefficient η overpotential (volt) rana a. majed al-khwarizmi engineering journal, vol.4, no.4, pp 26-36 (2008) 35 7. sub/superscripts: a anodic c cathodic corr corrosion pass passivity 8. references: [1] roebuck a. h., and pritchell t. r., materials protection, july 1966, p.16. [2] sundarrajah j., and ramchari t., corrosion, 17, 1961, p.39-41t. [3] bonewitz r. a., corrosion-nace, 29, 1973, p.215. [4] bohlmaun e. g., and posey f. a., proc. ist int. symp. on water desalination, washington, d.c., october 1961, p.306. [5] ahmad z., and rashidi s., proc. third middle east corrosion conf., bahrain, may 16-18, 1983, p.229-241. [6] nisandoglu k., and holton h., corrosion science, 18, 1978, p.835-849. [7] broli a., holton h., and sigurdson h., werkstoffe und korrosion, 26, 1975, p.629. [8] broli a., and holton h., 7th scandinavian, "corrosion congress", trondheim, may 1975. [9] j. janko wisk and r. juchniewicz, corrosion science, vol.20, p.841, (1980). [10] uhlig h. h., "corrosion and corrosion control", wiley, new york, (2000). [11] sherir l.l.,"corrosion",metal/environment reactions, second ed., 1, 1976, p.4-12. [12] saleh j. m., and al-haidari y. k, bull. chem. soc.(jpn), 62, 1989, p.1237. [13] al-shamma l. m., ph.d thesis, college of science, university of baghdad, october 1998. [14] al-saadie k.a.s., ph.d. thesis, college of science, university of baghdad, october 1997. [15] goodrad h., jepson w., bathwell m. and kane r., "the corrosion of light metals", (wiely, new york), p.1-218, (1967) [16] stern m. and grary a.l., j. electrochem. soc., vol.56, p.104, (1957). [17] stern m. and weisert e.d., proc. am. soc. test master, vol.59, p.1280, (1959). [18] sykes j.m., brit. corrosion j., vol.25, p.176, (1990). [19] bockeris j. o. m., and reddy a. k., "modern electrochemistry", press, new york, 1970, p.176. [20] fontana g., and green d., "corrosion engineering",mcgraw–hill, new york, (1978). [21] tomesanyi l., varga k., bartik i., horanyi g., and maleczki e., electrochimica acta, 34, 6, 1989, p.855-859. [22] zaki a., anti-corrosion, november 1986, p.4-11. 36-26، صفحة 4، اىعذد 4 مجية اىخىارزمي اىهنذسية اىمجيذ رنا عفيف ماجذ (2008) 36 زنل في محيىه هيذرومسيذ -تأثير أيىنات اىنيىريذ عيى سيىك اىتأمو ىسبينة اىمنيىً اىصىديىً عنذ اربع درجات حرارية رنا عفيف ماجذ هناء عرير اىقيسي هنذ باسو األطرقجي انجايؼــت انخكُٕنٕجٛــت /قسـى ُْذسـت انًـٕاد اىخالصـــة ( σδ modulator fractional-n يشسهت باسخؼًال يشكب حشدداث يٍ َٕع gaussianfsk انبحث انٗ حصًٛى ٔيحاكاة ٚٓذف يذٖ انفصم بٍٛ انقُٕاث ،(150kb/s)يٛكا ْشحض، َسبت حذفق انًؼهٕياث ( 900.4 – 869.9) يذٖ انخشدداث انخاسجت: ٔبانًٕاصفاث انخانٛت (500khz)، حقُٛاث انذٔائش . ْشحض يٍ انخشدد انخاسج10000دٚسبٛم ػُذ (85-)ياٚكشٔ ثاَٛت ٔيسخٕٖ ضٕضاء طٕس٘ 1صيٍ ححٕٚم خٕاص يثم قهت اسخبذاد انقذسة، صغش انحجى ٔ قهت .انحذٚثت ساًْج بشكم فاػم فٙ صٚادة انخكايم نهًشسالث ٔانًسخهًاث الشاساث انشادٕٚ اٌ انخضًٍٛ انًباشش بٕاسطت يشكب انخشدداث يٍ . انكهفت ْٙ انخٙ حؼخبش انًقٛاط انخاص بانخصًٛى ٔانخٙ يٍ خالنٓا ٚخى انحكى ػهٗ اداء انُظاو ٔرنك الٌ ْزِ انطشٚقت حؤيٍ انخٕاص انخٙ َحخاجٓا يثم قهت اسخبذاد انقذسة ٔصغش حى اقخشاحّ فٙ ْزا انبحثσδ( fractional n)َٕع فٙ دٔسة قفم انطٕس انشقًٙ نهسٛطشة ػهٗ انقًٛت انكسشٚت نًقسى انخشدد ٔبٕاسطخّ ٚخى ٔضؼجσδػًهٛت انخضًٍٛ يٍ َٕع . انحجى ٔقهت انكهفت انز٘ حى اسخخذايّ نهحصٕل ػهٗ (gaussian fsk)َٕع انخضًٍٛ . اصانت انطفٛهٛاث يغ يسخٕٖ طفٛهٛاث اقم ٔيسخٕٖ ضٕضاء طٕس٘ جٛذ انسٛطشة ػٍ بؼذ ، اَظًت االياٌ، اٌ انخطبٛقاث نٓزِ انًشسهت ْٙ قهت كهفت َقم انًؼهٕياث انالسهكٙ. كفاءة طٛفٛت ػانٛت فٙ االشاسة انًضًُت .ٔانؼذاد انالسهكٙ (rf)بٕاسطت اشاساث (microsoft word \323\332\317 \315\344\3241826) al-khwarizmi engineering journal al-khwarizmi engineering journal,vol. 13, no. 3, p.p. 1826 (2017) anaerobic digestion and codigestion of chlorella vulgaris microalgae biomass with wastewater sludge and dairy manure for biogas production saad h. ammar* sadiq riyadh khodhair** *, **department of chemical engineering/ college of engineering / al-nahrain university *email: saad_cheminet@yahoo.com **email: sadqkn@gmail.com (received 8 january 2017; accepted 23 march 2017) https://doi.org/10.22153/kej.2017.03.001 abstract anaerobic digestion process of organic materials is biochemical decomposition process done by two types of digestion bacteria in the absence of oxygen resulting in the biogas production, which is produced as a waste product of digestion. the first type of bacteria is known as acidogenic which converts organic waste to fatty acids. the second type of bacteria is called methane creators or methanogenic which transforms the fatty acids to biogas (ch4 and co2). the considerable amounts of biodegradable constitutes such as carbohydrates, lipids and proteins present in the microalgae biomass make it a suitable substrate for the anaerobic digestion or even co-digested with other organic wastes. the present work investigated methane biogas production by anaerobic codigestion of microalgae, chlorella vulgaris biomass with organic waste from several sources such as wastewater sludge and dairy manure waste in different proportions as an additional carbon supply to enhance anaerobic digestion and therefore biogas production. six bottles, employed as batch biodigesters each of 1 liter capacity, were used for that purpose at moderate conditions (35±2 oc). the produced biogas volume was monitored daily along 35 days and the results showed that the daily and cumulative biogas production was increased 4.5 times and 3 times for the bottles with 66.67% microalgae compared with the bottles with wastewater sludge or dairy manure waste only, respectively. keywords: anaerobic codigestion, biogas; dairy manure, microalgae chlorella vulgaris, wastewater sludge. 1. introduction anaerobic digestion is biological process, occurring naturally in which a group of anaerobic microorganisms convert organic substrates or biowaste into biogas containing methane (ch4) and carbon dioxide (co2) which is used as a renewable energy source [1].biogas energy provides a lot of advantages. the cost of electricity plants based on biogas is less than coal, oil, or nuclear power plants and be built quickly and simply. biogas is a renewable resource compared with these other current energy sources. biogas provides a superior source of energy that is beneficial to the environment [1, 2]. the bio-digestion of organic substances which contain mainly proteins, carbohydrates and fats takes place in four stages: hydrolysis, acidogenesis, acetogenesis and methanogenesis. in this process a series of microorganisms called acidogenic bacteria converts the organic wastes which contain carbohydrates, proteins, oils, and cellulose to short chain organic acids such as propionic, butyric and acetic acids and co2 and h2 gases and then these organic acids are converted with h2 gas to biogas by another type of bacteria called methanogenic bacteria in the absence of oxygen [2].in more accurately, anaerobic digestion include more than two saad h. ammar al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 1826 (2017) 19 stages of biogas production and many biochemical reactions are take place in these stages (fig.1). in the first stage, the large insoluble molecules (carbohydrates, proteins, oils, and cellulose) are hydrolyzed by enzyme catalyst which is provided by hydrolytic bacteria into more soluble small molecules like fatty and amino acids, and sugars. in the second stage (known as acidogenesis) these molecules are converted to smaller molecules such as carbonic acids, hydrogen, carbon dioxide, and ammonia. in the third stage (known as acetogenesis) carbonic acids are converted to acetic acids, co2 and h2. finally, the products from the third stage are converted to a mixture of ch4 and co2 by the methanogenic bacteria [4], [5]. fig. 1. degradation steps of anaerobic digestion process [3]. the codigestion process is carried out when more than one substrate feedstock has been used simultaneously. anaerobic digestion intrinsically became more stable when several types of substrates utilized at the same time are increased. the most common co-digestion systems include some major substrates like wastewater sludge or dairy manure waste with additional minor substrates of a single, or a variety of additional substrate like algae biomass, vegetable waste, whey, municipal sludge. etc. several technological and economic advantages of anaerobic co-digestion can be reported such as improving the balance of nutrient (c/n ratios in the biodigester), dilution of toxic compounds, enhancement the fluidity behavior of the single waste (i.e. make the digesting system more homogenous) and therefore increasing the biogas productivity [5], [6]. microalgae received large attention as a biofuel feedstock as a result of its high productivity, low lignin content, the possibility of planting on non-arable grounds or in lakes and are able to produce large amounts of biomass as compared with other conventional crops such as soybean, corn, canola, jatropha, and coconut. the photosynthetic efficiency of microalgae may reach 5% of the solar energy compared to 2% for earthly plants [7]. anaerobic digestion/codigestion of microalgae biomass has been widely used for that purpose because of high lipids, proteins and carbohydrates content in various amounts and different of these components affect the yield of biogas. in general, the lipids content in chlorella vulgarismicroalgae may reach up to 40% lipids by dry weight and this depends on the nutrients especially nitrogen content in the culturing media. it suggested by the most researchers such as sialve, b. et al. [8] that the lipid content has great influence on the biomethane production, followed by proteins and then carbohydrates. historically the first use of algae in the anaerobic digestion for biogas production was by golueke, c. g. et al. in 1957 [9], who’s used scenedesmusspp. and chlorella spp. species for that purpose and they compared the methane yield with other substance such as wastewater sludge at the same digestion temperature. depending on the environment and growth conditions, the freshwater microalgae chlorella vulgaris have proportions of proteins, lipids and carbohydrates as (6-52 %), (7-23 %) and (523%) respectively. the carbon-to-nitrogen ratio (c/n) ratio in microalgae chlorella vulgaris is inversely proportional to protein content in these species and it is usually low compared with other terrestrial plants (10/1 for microalgae while it is 36/1 for terrestrial plants) [8]. anaerobic digesting of high protein content microalgae (and therefore low c/n ratio) could result in high total ammonia (nh4 + ions and free ammonia) accumulated and also high volatile fatty acids presented in the digester mixture [10]. high concentration of total ammonia and volatile fatty acids in the digesting mixture would decrease the activity of methanogenic bacteria and further accumulation of free ammonia could fail the anaerobic digestion process, this is called ammonium toxicity where the unionized hydrophobic (free) ammonia saad h. ammar al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 1826 (2017) 20 diffuses passively across the cell membranes of methanogenic bacteria (which is have high sensitivity to ammonia presence among the other bacteria hydrolytic, acidogenesis and acetogenesis) causing proton imbalance or potassium lack where it expresses its toxicity [11]. it can adopt several ways to avoid the impact of low c/n ratios, one method to avoid excessive ammonia accumulation and therefore improving the performance of digestion process is to increase the c/n ratios by adding high carbon (and low protein) content materials as co-substrates to the digester [12]. this rule has attracted us to investigate the ability of wastewater sludge and dairy manure waste as high c/n ratio substrates for biogas production when co-digested with microalgae chlorella vulgaris biomass. in the present study, the microalgae chlorella vulgarisbiomass wasbiodigested simultaneously with wastewater sludge and dairy manure waste in different quantities as an extra source of organic materials to enhance the biomethane yield. 2. experimental 2.1. raw materials microalgae chlorella vulgarisbiomass provided from previous culture work by ammar, s. h. in 2016 [13] cultured in 2.5-liter semi-continuous airlift photobioreactor using 80 mg/l of 20:20:20+te npk as nutrients, 6 lpm air flowrate, photoperiod cycle of 20:4 h, ph of 6-7 and temperature of 22 ± 1°c for biomass production. the produced microalgae biomass concentration was 0.316 g/l and then to be concentrated to 2.6 g/l by centrifugation before used. dairy manure waste (dmw) was obtained from a local farm located in al-fudhaliyah region, east of baghdad, iraq. wastewater sludge (wws) was provided from the environment and water department, ministry of science and technology, baghdad, iraq. the water content in wws was 5%. after receiving, the wws stored immediately in a fridge at about 5°c until be used. the wws was diluted to 33 % in water before digestion. 2.2 experimental setup and procedure substrates codigestion experiments were conducted in six 1-liter glass bottles (each 750 ml working volume) as batch biodigesters placed in a water bath with constant temperature at 35±2 °c. each digester bottle was air tight by rubber septum, the outlet biogas from each digester was collected by 0.25 l glass bottle filled with water worked as biogas storage vessel. the amount of biogas produced was measured daily by using the water displacement method as shown in fig.2. the experimental setup was viewed photographically in fig.3. each bioreactor was loaded with the feedstock systems as described in table (1). the wastewater sludge and dairy manure waste systems were diluted to 33% vol. in water before used. the methane and co2 gases concentrations were measured by using gem 5000 gas analyzer (geotechnical instrumentals, ltd. uk). table 1, proportions of feedstock systems used in this study (m = microalgae of concentration = 2.6 g/l, wws= wastewater sludge, dmw = dairy manure waste) run no. digester no. (total reactor volume = 1 l, working volume = 750 ml, substrate (wws or dmw) % used = 33 %vol., microalgae concentration used = 2.6 g/l) 1 2 3 4 5 6 1 500 ml m + 250 ml dmw 375 ml m + 375 ml dmw 250 ml m + 500 ml dmw 100%, (33%vol.) dmw (250 ml dmw + 500 ml water) 100% m (with 2 gm of wastewater sludge as inoculum) 500 ml m + 125 ml wws + 125 ml dmw 2 500 ml m + 250 ml wws 375 ml m + 375 ml wws 250 ml m + 500 ml wws 100% (33%vol.) wws (250 ml wws + 500 ml water) saad h. ammar al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 1826 (2017) 21 fig. 2. schematic diagram of one experimental bioreactor used for anaerobic co-digestion. fig. 3. photographic view of the experimental bioreactors in use. 3. results and discussion 3.1.microalgae-dairy manure waste system fig.4 shows the results of microalgae diary manure system daily codigesting process (fig.4 a) and cumulative biogas production (fig.4 b) at different combinations of microalgae in cow manure system while fig.5 shows the maximum biogas production for the five combinations of microalgae in dairy manure system. as shown in these figures, the total biogas production increased when using combined microalgae and dairy manure. the combination of 500 ml microalgae and 250 ml dairy manure waste give higher biogas yield than other combinations resulting in a biogas production of 1671 ml composed by 43 % of methane at day 30 as listed in table 2. the maximum efficiency of daily biogas and methane production was observed in 6th and 8th day (two peaks) of the 500 ml m + 250 ml dmw combination (figs 4.a and 5.a). table 2, total biogas and methane yields from microalgae dairy manure waste system at day-30. system composition total biogas volume (ml) methane volume (ml) methane % 750 ml m 147 95 64.8 750 ml dmw 557 300 54 250 ml m + 500 ml dmw 838 450 53.6 375 ml m + 375 ml dmw 907 543 59.8 500 ml m + 250 ml dmw 1671 719 43 fig. 4. daily (a) and cumulative (b) biogas production (ml) for codigestion of microalgae-dairy manure waste system. saad h. ammar al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 1826 (2017) 22 fig. 5. daily (a) and cumulative (b) biomethane production for codigestion of microalgae-dairy manure waste system. 3.2 . microalgae-wastewater sludge system fig.6 shows the daily (a) and cumulative (b) biogas production of microalgae wastewater sludge codigesting process which included five combinations while fig.7 shows daily methane production. it is clear also that whenincreasing the microalgae percent, the daily biogas production increased. the maximum daily biogas yields were 68 ml, 150 ml, and 300 ml for 250 ml microalgae + 500 ml wastewater sludge, 375 ml microalgae + 375 ml wastewater sludge and 500 ml microalgae + 250 ml at the 13th, 11th, and 6th day respectively, i.e. biogas yield increase with increasing microalgae proportion in the microalgae-wastewater sludge system. these results were better when compared with microalgaedairy manure waste system at the same proportions as shown in figs.8 and 9, this is specifically due to high carbon content present in wastewater sludge [2]. table 3 show total biogas and methane yields from microalgaewastewater sludge system at day-30. fig. 6. daily (a) and (b) cumulative total biogas production (ml) for codigestion of microalgaewastewater sludge (m+wws) system. fig. 7. daily (a) and (b) cumulative biomethane production (ml) for codigestion of microalgae saad h. ammar al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 1826 (2017) 23 wastewater sludge (m+wws) system. table 3, total biogas and methane yields from microalgae wastewater sludge system at day-30. system composition m: microalgae dmw: dairy manure waste total biogas volume (ml) methane volume (ml) methane % 750 ml m 943 513.272 67.8 750 ml dmw 1693 821.916 62 250 ml m + 500 ml dmw 2590 1127.69 61.6 375 ml m + 375 ml dmw 697 374.956 63.8 500 ml m + 250 ml dmw 147 95.31 54 fig. 8. comparison between max daily biogas yield of microalgae-wastewater sludge and microalgae-dairy manure waste systems. fig. 9. comparison between max biomethane yield of microalgae-wastewater sludge and microalgae-dairy manure waste systems. 3.3 microalgae -dairy manure wastewastewater sludge system figs. 10 and 11 show the daily biogas volume and cumulative biogas respectively produced from system contain 500 ml microalgae, 125 ml wastewater sludge and 125 ml wastewater sludge. fig. 11 shows the daily methane production for the same system. the maximum biogas yield was recorded as 162 ml at the 8th day while the maximum biomethane yield was 80.46 ml achieved also at the 8th day of codigestion. fig. 10. daly (a) and cumulative (b) biogas production for microalgae, dairy manure waste and wastewater sludge (500 ml m+125 ml dmw+125 ml wws) system saad h. ammar al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 1826 (2017) 24 fig. 11. daily biomethane production (ml) for codigestion of microalgae-wastewater sludgedairy manure waste system it’s known that biomethane production curves are often divided into three stages: lag phase, decomposition phase and flattening phase [14]. the lag phase is the time from the start of the experiment to the start of the biomethane production in the bioreactors. it can be seen in all figures that there is no clear lag phase for the bottles with high microalgae content but a short lag phase for the bottles with low microalgae content. 4. conclusions this study was performed to assess the biomethane generation potential from codigestion of microalgae chlorella vulgaris biomass with two extra carbon source including wastewater sludge and dairy manure waste to overcome the problem of low c/n ratio in microalgae. by comparing the single digestion with codigestion of combined wastes, the codigestion resulted in higher biogas yields and also had a positive effect on the methane content of the biogas produced due to positive synergisms established in the digestion medium. microalgae-wastewater sludge system was give higher biogas yield than microalgae-dairy manure waste at the same proportions. notation c carbone n nitrogen c/n carbone to nitrogen ratio npk nitrogen-phosphor-potassium dmw dairy manure waste m microalgae wws wastewater sludge acknowledgement this work is part of final year graduation project. the support provided by chemical engineering department is greatly acknowledged. the authors also acknowledge the staff of the ministry of science and technology / environment and water department, baghdad (iraq) for providing wastewater sludge and their support. 6. references [1] williams, c. l., willard, s., kouba, a., sparks, d., holmes, w., falcone, j. & brown, a. "dietary shifts affect the gastrointestinal microflora of the giant panda (ailuropodamelanoleuca)". journal of animal physiology and animal nutrition, 97(3), 577585, (2013). [2] ward, a. j., lewis, d. m., & green, f. b. "anaerobic digestion of algae biomass: a review." algal research, 5, 204-214, (2014). [3] prakash, n. b., sockan, v., &jayakaran, p. "mathematical model development for bod removal efficiency in tannery waste treatment ". british journal of environmental sciences, 3(1), 1-12, (2015). [4] wu, w. "anaerobic co-digestion of biomass for methane production: recent research achievements". optimization, 1, 1vs, (2007). [5] kangle, k. m., kore, s. v., kore, v. s., &kulkarni, g. s. "recent trends in anaerobic codigestion: a review". universal journal of environmental research and technology, 2(4), 210-219, (2012). [6] mata-alvarez, j., dosta, j., macé, s., &astals, s. "codigestion of solid wastes: a review of its uses and perspectives including modeling." critical reviews in biotechnology, 31(2), 99-111, (2011). [7] salerno, m., nurdogan, y., & lundquist, t. j. "biogas production from algae biomass harvested at wastewater treatment pond"s (p. 18). american society of agricultural and biological engineers, (2009). saad h. ammar al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 1826 (2017) 25 [8] sialve, b., bernet, n., & bernard, o. "anaerobic digestion of microalgae as a necessary step to make microalgal biodiesel sustainable". biotechnology advances, 27(4), 409-416, (2009). [9] golueke, c. g., oswald, w. j., &gotaas, h. b. "anaerobic digestion of algae". applied microbiology, 5(1), 47, (1957). [10] yen, h. w., &brune, d. e. "anaerobic codigestion of algal sludge and waste paper to produce methane". bioresource technology, 98(1), 130-134, (2007). [11] chen, y., cheng, j. j., & creamer, k. s. "inhibition of anaerobic digestion process: a review". bioresource technology, 99(10), 4044-4064, (2008). [12] samson, r., &leduy, a. "improved performance of anaerobic digestion of spirulina maxima algal biomass by addition of carbon-rich wastes." biotechnology letters, 5(10), 677-682, (1983). [13] ammar saad h. "cultivation of microalgae chlorella vulgaris in airlift photobioreactor for biomass production using commercial npk nutrients". al-khwarizmi engineering journal, 12(1), p.90-99, (2016) [14] olsson, j., feng, x. m., ascue, j., gentili, f. g., shabiimam, m. a., nehrenheim, e., &thorin, e. "co-digestion of cultivated microalgae and sewage sludge from municipal waste water treatment". bioresource technology, 171, 203-210, (2014). )2017( 18-26، صفحة 3د، العد13دجلة الخوارزمي الهندسية المجلم سعد حنش عمار 26 ة كلوريلال فولكيرس مع حمأ مياه الصرف المفرد والمشترك للطحالب الدقيق م الالهوائيضاله الماشية النتاج الغاز الحيويالصحي ومخلفات **صادق رياض خضير *سعد حنش عمار نجامعة النهري كلية الهندسة/ /*, **قسم الهندسة الكيمياوية saad_cheminet@yahoo.comكتروني: لبريد االال* sadqkn@gmail.com**البريد االلكتروني: الخالصة مة بغياب االوكسجين منتجة الغاز الحيوي ضطة نوعين من البكتريا الهاام الالهوائي للمواد العضوية هي عملية تفكك كيميائية حيوية تتم بوسضعملية اله م. النوع االول من البكتريا تعرف ببكتريا اسيدوجين تقوم بتحويل الجزيئات العضوية الى حوامض شحمية ومن ثم تقوم نوع اخر ضلعملية اله بوصفه ناتجا وثاني اوكسيد 4chمن البكتريا تعرف ببكتريا صانعة الميثان او ميثانوجين بتحويل هذه الحوامض الشحمية الى غاز حيوي يتكون من الميثان م الالهوائي للكتلة الحيوية من الطحالب الخضراء الدقيقة كلوريلال ضحث الحالي يدرس انتاجية غاز الميثان الحيوي بواسطة عملية اله. الب2coالكاربون للكاربون بنسب مختلفة بوصفه مصدرا اضافيافولكيرس بصورة مشتركة مع مخلفات عضوية مختلفة مثل حمأ مياه الصرف الصحي ومخلفات الماشية لتر تحت ضروف معتدلة ١مفاعالت حيوية حجم كل مفاعل بوصفها هظم الالهوائي ومن ثم انتاجية الغاز الحيوي. تم استخدام ست قناني زجاجية لتحسين ال مرة للمفاعل الحاوي ٣مرة و ٤٫٥واظهرت النتائج ان انتاجية الغاز الحيوي تزداد بمقدار ايوم ٣٥. تم مالحظة عملية االنتاج يوميا وعلى مدى oم٢±٣٥ طحالب مقارنة مع مفاعل الذي يحوي فقط حمأ مياه الصرف الصحي او مخلفات الماشية على التوالي. %٦٦٫٦٧على 62-69محمود وسامر al-khwarizmi engineering journal,vol. 13, no. 1, p.p. proposed hybrid sparse adaptive algorithms for system mahmood a. k abdulsattar *,**department of electrical engineering *email:mahmood.abdulsattar@googlemail.com **email: (received 29 august https://doi.org/10.22153/kej.2017.12.003 abstract for sparse system identification,recent suggested algorithms are attracting lms (za-lms), reweighted zerohave modified the cost function of the conventional lms algorithm by adding a constraint of coefficients sparsity. and so, the proposed algorithms are named ℓ�-za merging twoconstraints from previous algorithms to improve theconvergence rate system. in this paper, a complete analysis was done gaussian sequence for input signal. the discuss algorithms and system sparsity was observed. in addition and the last recent algorithms were presented and the necessary conditions to improve convergence rate. finally, the results presented to match closely by a wide-range of parameters. keywords: adaptive filter, ℓ�-lms, zero-attracting, p 1. introduction adaptive filtering is a difficult problem when the involved impulse response is sparse. least mean square (lms) algorithm used in many applications for example system identification, echo cancelation, and channel equalization, due to its easy implementation, good performance, and high robustness, [1–3]. the impulse response of a sparse system contains many zeros or near-zero coefficients and few large ones [4]. for this system, the conventional lms not ever takes improvement of the sparsity. in latest years, a number of algorithms suggested depend on lms to the feature of sparsity. the proportionate nlms(pnlms) algorithm and its improved which use the individual step size with respect coefficients of filter in proportional to improve khwarizmi engineering journal,vol. 13, no. 1, p.p. 6269 (2017) proposed hybrid sparse adaptive algorithms for system identification k abdulsattar* samer hussein ali** engineering /college of engineering/ university of baghdad mahmood.abdulsattar@googlemail.com : msc_eng_samerhussein@yahoo.com august 2016; accepted 19 december 2016) https://doi.org/10.22153/kej.2017.12.003 recent suggested algorithms are ℓ�-norm least mean square ( -attracting lms (rza-lms), and p-norm lms (p-lms) have modified the cost function of the conventional lms algorithm by adding a constraint of coefficients sparsity. and za-lms, ℓ�-rza-lms, p-za-lms and p-rza-lms that are designed by m previous algorithms to improve theconvergence rate and steady state of was done for the theoretical operation of proposed algorithms by exited white gaussian sequence for input signal. the discussion of mean square deviation (msd) with regard to parameters of observed. in addition, in this paper, the correlation between proposed algorithms re presented and the necessary conditions of these proposed algorithms results of simulations are compared with theoretical study (?), which is of parameters.. attracting, p-lms, mean square deviation, sparse system identification problem when se response is sparse. least (lms) algorithm used in many applications for example system identification, echo cancelation, and channel equalization, due to its easy implementation, good performance, and the impulse response of a sparse system zero coefficients and few large ones [4]. for this system, the conventional lms not ever takes improvement of years, a number of on lms to improve roportionate and its improved ones, the individual step size with respect the to improve the convergence rate of them[5, 6]. developed sparse signal processing part [7 the estimation of these algorithms is applied the features of unknown impulse response then added sparsity constraints to the cost function of gradient descent. it is essential to deportment a th examination of proposed algorithms. numerical simulations proved the proposed algorithm better performance than recent sparse system identification, minimized steady-state msd convergence rate. 1.1. relation to other works the mean square evaluation has been illustrated for lms algorithm and a share of its deviations, the optimal algorithm parameters has al-khwarizmi engineering journal proposed hybrid sparse adaptive algorithms for system university of baghdad norm least mean square (ℓ�-lms), zerolms) algorithms, that have modified the cost function of the conventional lms algorithm by adding a constraint of coefficients sparsity. and lms that are designed by of msd for sparse for the theoretical operation of proposed algorithms by exited white ion of mean square deviation (msd) with regard to parameters of between proposed algorithms algorithms were planned are compared with theoretical study (?), which is sparse system identification. [5, 6]. the recently developed sparse signal processing part [7–11]. the estimation of these algorithms is applied the features of unknown impulse response then added sparsity constraints to the cost function of gradient it is essential to deportment a theoretical algorithms. numerical simulations proved the proposed algorithms have algorithms for sparse system identification, due to both and improved the mean square evaluation has been and a share of its deviations, the optimal algorithm parameters has pdf created with pdffactory trial version www.pdffactory.com mailto:mahmood.abdulsattar@googlemail.com https://doi.org/10.22153/kej.2017.12.003 mailto:mahmood.abdulsattar@googlemail.com mailto:msc_eng_samerhussein@yahoo.com https://doi.org/10.22153/kej.2017.12.003 http://www.pdffactory.com http://www.pdffactory.com mahmood a.k abdulsattar al-khwarizmi engineering journal, vol. 13, no. been selected to characterize the theoretically performance. lms algorithm was proposed by widrow for the first time in [12] and its performance was studied in [13]. later, the mathematical frame of mean square analysis was established by horowitz and senne via examining the coefficients vector and succeeded the closed form appearance of msd [14], which wa simpler by weinstein and feuer [15]. a brief analysis, which planned in [16] depend on a style of adaptive algorithms, that presents linear time invariant processes depend on the instantaneous of gradient vector and the lms is the simplest algorithm. likewise, the examination normalized lms (nlms) has involved extremely attention [17,18].even so, the styles stated, which are professional in their own background, might no longer be straight usedin lms, since its nonlinearity. the msd analysis of za-lms and p-lms have been operated in [19, 20]. 1.2. main contribution the contribution which presented in this paper is on the performance analysis of steady then, the stability condition on step size is chosen. after that, the rule to select the parameter for steady-state performance is suggested. finally, the steady-state msd is achieved with the optimal parameter for proposed algorithms over the traditional algorithm. another contribution is on behavior of instantaneous analysis that implies the convergence rate for lms algorithm.. also, the convergence rates of proposed algorithms are compared with that of standard lms. 2. background 2.1. standard lms algorithm let � = [ℎ�ℎ�ℎ� … . . ℎ���]�denotes the coefficient vector of filter, e.g., an impulse response of fir filter; �(�) = [� (�)1) … … . � (� − l + 1)] � denotes a vector of input signal where l is the filter length, �(n) denotes a desired signal, �(�) illustrates the observation noise vector, �(�) denotes the output signal��(�) illustrates the estimated coefficient of adaptive filter at iterationn and e(n) denotes an estimation error. khwarizmi engineering journal, vol. 13, no. 2, p.p. 63 been selected to characterize the theoretically performance. lms algorithm was proposed by the first time in [12] and its performance was studied in [13]. later, the analysis was established by horowitz and senne via examining succeeded the closed[14], which was make simpler by weinstein and feuer [15]. a brief on a style of adaptive algorithms, that presents linear timeon the instantaneous gradient vector and the lms is the simplest examination of has involved the styles , which are professional in their own usedinℓ�lms, since its nonlinearity. the msd analysis of lms have been operated in [19, this paper is on the performance analysis of steady-state. then, the stability condition on step size is parameter . finally, with the optimal parameter for proposed algorithms over the vior of implies the .. also, the convergence rates of proposed algorithms are denotes the , an impulse ) � (� − denotes a vector of input denotes a illustrates the observation denotes the output signal, the estimated coefficient vector ) denotes an fig. 1. adaptive system identification (direct system modeling). �(�) = ��(�) � + �(�) �(�) = ��(�)��(�) �(�) = �(�) − �(�) the cost function of traditional expressed as ℂ(�) = �� �(�) � the filter coefficient vector for lms is updated by: ��(� + 1) = ��(�) − � �ℂ(�)���(�) ��(� + 1) = ��(�) + ��(�)�(�) where � is the step size of adaptation 3. ��-lms algorithm this algorithm was derived by inserting an norm constraint as a sparsity constraint to the cost function of traditional lms to convergence of lms algorithm for sparse system identification [٤]. the cost function is presented by the factorization ℂ(�) = 12 �(�) � + ��� �(1� ��� − �� the update of adaptive filter coefficient:��(� + 1) = ��(�) + � �(�) �(�) �(�) = � ���(��(�)) ���|�� (�)| where ��� = ����is a parameter stabilize the estimation of error and the constraint, parameter β is a positive value that is applied to define the area of zero attraction [4], sgn (∙)is a component-wise sign function defined as , p.p. 6269(2017) 1. adaptive system identification (direct …(1) …(2) …(3) traditionallms ℂ(�) is …(4) coefficient vector for lms is ( ) …(5) is the step size of adaptation [1]. this algorithm was derived by inserting anℓ�norm constraint as a sparsity constraint to the cost lms to improve the convergence of lms algorithm for sparse system the cost function is presented by the factorization ��|��� (�)|) … (6) the update of adaptive filter coefficient: ( ) − ����(�) … (7) …(8) is a parameter used to error and the latest , parameter β is a positive value that is applied to define the area of zero attraction [4], wise sign function which pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com mahmood a.k abdulsattar al-khwarizmi engineering journal, vol. 13, no. ���(�) = �� |�|⁄ � ≠ 00 � = 0� by using the first order taylor series of exponential functions, the computational complexity of (٧) can be reduced as followed [���|�| ≈ � 1 − �|�||�| ≤ 1 ��0 �����ℎ���� substituting (9) and (10) into (8), function can be expressed clearly as �(�) = ⎩⎨ ⎧−����(�) − �, − 1 �� ≤ ℎ��(�) < 0−����(�) + �, 0 ≤ ℎ��(�) < 1 ��0, �����ℎ��� fig. 2 describes the characteristic of the function s(x), which has zero-attraction effect. fig. 2. function s(n) for zero-attraction effect. 4. (za-lms) and (rza-lms) algorithm in the zero attractor, a cost function ℂ�� defined by combining square error and penalty of estimation coefficients vector sparsity constraint ℂ��(�) = �� �(�) � + ���||��(�)|| � the update filter of (za-lms) is determined equally ��(� + 1) = ��(�) + ��(�)�(�) −��� ���(��(�)) where ��� = ����is the factor used to control the force of sparsity penalty.in za-lms all taps are forced to zero uniformly, and its performance will weaken in not sparse systems, then lms use individual zero attractors for different filter taps and its cost function is ℂ���(�) = �� �(�) � + ���� ∑ log��(1 +�����|ℎ��(�)|) the update filter of (rza-lms) is defined as khwarizmi engineering journal, vol. 13, no. 2, p.p. 64 …(9) st order taylor series of exponential functions, the computational ) can be reduced as followed [٤], …(10) substituting (9) and (10) into (8), function �(∙) 0�� ⎭⎬ ⎫ …(11) fig. 2 describes the characteristic of the attraction effect. attraction effect. algorithms ��(�) is defined by combining square error and �� norm penalty of estimation coefficients vector as a …(12) lms) is determined … (13) to control lms all taps are forced to zero uniformly, and its performance will weaken in not sparse systems, then rzalms use individual zero attractors for different + …(14) lms) is defined as ��(� + 1) = ��(�) + ��(�)�(�)���� ���(��(�)) ��� |��(�)| where���� = ������, where parameter controls the similarity between (15) and (7). 5. p-lms algorithm the cost function of (p-lms) ℂ by combining square error and ���norm penalty coefficient vector as shown as ℂ�(�) = �� �(�) � + ��||��(�)||�� the update equation of (p-lms) ��(� + 1) = ��(�) + ��(�) �(�)��� ���(��(�)) ��|��(�)|��� a parameter p has effect on the estimation bias in addition to the strength of sparsity correction. a parameter �� = ��� is used to stabilize the constraint term and the estimation square error. 6. proposed algorithms a. ��-za-lms and ��-rza-lms the proposed cost functions of andℓ�-rza-lms are designed by merging between ℓ�-norm with ℓ�-norm on the coefficients of filter constraints and/ or reweighted zero attractor constraints into the cost function of lms to improve the convergence of it. they obviously presentin (18) and (19). ℂ(�) = �� �(�) � + ���||��(�)|| � +���|��� (�)|) ℂ(�) = �� �(�) � + ���� ∑ log�������|ℎ�� (�) |) + ��� ∑ (1���� − ���|�� the update of adaptive filter coefficient ��(� + 1) = ��(�) + � �(�) �(�)��� ���(��(n)) − ���� ���(��(n ��(� + 1) = ��(�) + � �(�) �(�)���� ���(��(�)) ��� |��(�)| − ���� ���(��(n) b. p-za-lms and p-rza-lms this proposed algorithms have designed by merging between p-norm with constraints on the coefficients of filter and/or , p.p. 6269(2017) ( ) − …(15) , where parameter � controls the similarity between (15) and (7). ℂ�(�) is defined norm penalty the ) …(16) lms) as ( ) − …(17) a parameter p has effect on the estimation bias in addition to the strength of sparsity correction. a is used to stabilize the constraint term and the estimation square error. lms algorithms the proposed cost functions of ℓ�-za-lms lms are designed by merging norm on the coefficients of filter constraints and/ or reweighted zero attractor constraints into the cost the convergence rate obviously presentin (18) and (19). + ��� ∑ (1���� − ...(18) ��(1 +�� (�)|) …(19) the update of adaptive filter coefficient ( ) −n)) ���|�� (�)| …(20) ( ) −)) ���|�� (�)| …(21) lms algorithms this proposed algorithms have designed by norm with ℓ�-norm constraints on the coefficients of filter and/or pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com mahmood a.k abdulsattar al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 6269(2017) 65 reweighted zero attractor constraints into the lms cost function to increase the convergence of lms for sparse systems. they obviously present in (22) and (23). ℂ(�) = �� �(�) � + ���||��(�)|| � + ��||�� (�)||�� …(22) ℂ(�) = �� �(�) � + ���� ∑ log��(1 +�����|ℎ�� (�) |) + ��||�� (�)||�� …(23) the update of adaptive filter coefficient ��(� + 1) = ��(�) + � �(�)�(�) −������(��(n)) − ��� ���(��(�))��|��(�)|��� …(24) ��(� + 1) = ��(�) + � �(�)�(�) −���� ���(��(�)) ��� |��(�)| − ��� ���(��(�))��|��(�)|��� …(25) 7. simulation results we illustrated the performance of the proposed algorithms for system identification via a computer simulation. an impulse response of unknown system consists 16 coefficients may be one of three systems, the first impulse response, the value of 5th tap equal 1 and the others equal zero is called sparse system, the second impulse response, the values of odd taps equal 1 and the others equal zero is called semi sparse system and the third impulse response, the values of all taps equal 1 is called not sparse system. a white gaussian noise used as input signal and observed noise with variances 1 and 0.01 individually. the first experiment is planned to examine the convergence rate performance of sparse system with apply our methods with different value of�. the parameters of algorithms are providing in tables 1, 2, 3, and 4.the results of algorithms are achieved from independent simulations, as shown in fig’s.3, .4, .5, and .6, these are obvious that the convergence rate of proposed algorithms are more rapidly and produces lower msd than the lms are done in a large value of �. the second experiment is planned to test the performance of the proposed algorithms via various sparsity. the unknown system here is sparse system, then after 1500 iterations are semi sparse system and later, after 3000 iteration be not sparse system. the parameters are set as in table 5.fig. 7 and fig. 8 show the average estimate of mean square deviation (msd). both the ℓ�-rzalms and the p-rza-lms return better steadystate msd and faster convergence than other algorithms (before the 1500th iteration)when the system is sparse. when the number of non-zero taps increases to 8, (after the 1500th iteration and before the 3000th iteration) when the system is semi sparse, the performance of algorithms deteriorate while the ℓ�-rza-lms and p-rzalms maintains the best performance and the msd of ℓ�-rza-lms algorithm is lower than that of ℓ�-za-lms algorithm and the msd of prza-lms algorithm is lower than that of p-zalms algorithm among this filter. when the system is non-sparse (after 3000 iterations), the ℓ�-za-lms and p-rza-lms maintain the best performance with this filter while the others still achieves comparably to the lms. the third experiment suggests a system with 128-taps with 8 nonzero coefficients as shown in fig 9. the iterations of all filters are 5000. table 6 present the parameters of algorithms for this experiment, the average msd is shown in fig.10 and fig.11. for this long sparse system, the convergence rate of all filters is almost the best form that of lms, but the msd of ℓ0-rza-lms and p-rza-lms are relatively minimum. table 1, parameters of ��-za-lms algorithm. � ��� � ��� lms 0.025 ℓ�-za-lms1 0.0156 1.6 ∗ 10�� 5 1.6 ∗ 10�� ℓ�-za-lms2 0.025 2.5 ∗ 10�� 5 2.5 ∗ 10�� ℓ�-za-lms3 0.0313 3 ∗ 10�� 5 3 ∗ 10�� table 2, parameters of ��-rza-lms algorithm. � ��� � ���� lms 0.025 ℓ�-rzalms1 0.0156 8 ∗ 10�� 5 1.6∗ 10�� ℓ�-rzalms2 0.025 1.3∗ 10�� 5 2.5∗ 10�� ℓ�-rzalms3 0.0313 1.6∗ 10�� 5 3 ∗ 10�� table 3, parameters of p-za-lms algorithm. � �� � ��� lms 0.025 p-za-lms1 0.0156 1.6 ∗ 10�� 0.6 1.6 ∗ 10�� p-za-lms2 0.025 2.5 ∗ 10�� 0.6 2.5 ∗ 10�� p-za-lms3 0.0313 3 ∗ 10�� 0.6 3 ∗ 10�� table 4, parameters of p-rza-lms algorithm. � �� � ���� lms 0.025 p-rza-lms1 0.0156 2.4 ∗ 10�� 0.6 4 ∗ 10�� p-rza-lms2 0.025 4 ∗ 10�� 0.6 6 ∗ 10�� p-rza-lms3 0.0313 5 ∗ 10�� 0.6 8 ∗ 10�� pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com mahmood a.k abdulsattar al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 6269(2017) 66 table 5, parameters of algorithms for second experiment. � ��� � ��� ���� � �� p lms 0.025 ℓ�-lms 0.025 8 ∗ 10�� 5 za-lms 0.025 1.6 ∗ 10�� rza-lms 0.025 2.5 ∗ 10�� 10 p-lms 0.025 4 ∗ 10�� 0.6 ℓ�-za-lms 0.025 2.5 ∗ 10�� 5 2.5 ∗ 10�� ℓ�-rza-lms 0.025 1.3 ∗ 10�� 5 2.5 ∗ 10�� 10 p-za-lms 0.025 2.5 ∗ 10�� 2.5 ∗ 10�� 0.6 p-rza-lms 0.025 6.3 ∗ 10�� 10 4 ∗ 10�� 0.6 table 6, parameters of algorithms for third experiment. � ��� � ��� ���� � �� p lms 0.0078 ℓ�-lms 0.0078 2.5 ∗ 10�� 5 za-lms 0.0078 6 ∗ 10�� rza-lms 0.0078 2.5 ∗ 10�� 10 p-lms 0.0078 8 ∗ 10�� 0.6 ℓ�-za-lms 0.0078 8 ∗ 10�� 5 8 ∗ 10�� ℓ�-rza-lms 0.0078 8 ∗ 10�� 5 2 ∗ 10�� 10 p-za-lms 0.0078 8 ∗ 10�� 8 ∗ 10�� 0.6 p-rza-lms 0.0078 6 ∗ 10�� 10 2.5 ∗ 10�� 0.6 fig. 3. learning curves of ��-za-lms withdifferent �, driven by white signal. fig. 4. learning curves of ��-rza-lms with different�, driven by white signal. fig. 5. learning curves of p-za-lms with different �, driven by white signal. fig. 6. learning curves of p-rza-lms with different �, driven by white signal. 0 300 600 900 1200 1500-50 -40 -30 -20 -10 0 10 sparse system time index m sd v al ue in d b lms l0-za-lms1 l0-za-lms2 l0-za-lms3 0 300 600 900 1200 1500 -50 -40 -30 -20 -10 0 10 sparse system time index m sd v al ue in d b lms l0-rza-lms1 l0-rza-lms2 l0-rza-lms3 0 300 600 900 1200 1500-40 -30 -20 -10 0 10 sparse system time index m sd v al ue in d b lms p-za-lms1 p-za-lms2 p-za-lms3 0 300 600 900 1200 1500-50 -40 -30 -20 -10 0 10 sparse system time index m sd v al ue in d b lms p-rza-lms1 p-rza-lms2 p-rza-lms3 pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com mahmood a.k abdulsattar al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 6269(2017) 67 fig. 7. the performance of different algorithms of varying sparsity, driven by white signal. fig. 8. the performance of different algorithms of varying sparsity, driven by white signal. fig. 9. 128-order adaptive filter. fig. 10. the performance of 128-order adaptive 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[20] f. y. wu, student member, ieee, and f. tong, member, ieee “non-uniform norm constraint lms algorithm for sparse system identification” ieee communication letter, vol. 17, no. 2, feb. 2013. pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com )2017( 62-69، صفحة 2، العدد13دجلة الخوارزمي الھندسیة المجلم عبد الستارمحمود عبد القادر 69 التكیفیة المتناثرة األنظمةالخوارزمیات التكیفیة الھجینة المقترحة لتحدید ھویة **سامر حسین علي* محمود عبد القادر عبد الستار جامعة بغداد/ كلیة الھندسة /ئیةالكھربا الھندسة قسم mahmood.abdulsattar@googlemail.com : االلكتروني البرید* msc_eng_samerhussein@yahoo.com : االلكتروني البرید** الخالصة -ℓ�-norm least mean square (ℓ�-lms), zero-attracting lms (za-lms), reweighted zero-attracting lms (rza لتحدید النظام التكیفي المتناثر اقترحت سابقا خوارزمیات وھي lms), and p-norm lms (p-lms). ℓ�-za-lms, ℓ�-rza-lms, p-za-lms and p-rza-lms الخوارزمیات المقترحة حالیا ھي وأسماء. lmsتقید مناسب لدالة كلفة بإضافةوذلك lmsعن طریق تعدیل دالة الكلفة للـ وفي ھذا البحث یوجد تحلیل ریاضي متكامل للخوارزمیات . للنظام المتفرقب ومعدل التقار msdلحسین lmsتقییدین لدالة كلفة بإضافةوصممت فیما یتعلق بالمعلومات الخاصة لكل خوارزمیة ونسبة التناثر msdومناقشة نتائج ، الداخلة للنظام اإلشارةتمثل wgnالمقترحة عن طریق استعمال بین الخوارزمیات المقترحة حالیا والخوارزمیات المقترحة سابقا والشروط الضروریة للخوارزمیات المقترحة حالیا والتي تبین العالقة فضال عن. المبینة .المحاكات والنتائج النظریة باالعتماد على المعلومات لكل خوارزمیة أنظمةھناك مقارنة بین نتائج ، وأخیرا. تحسین معدل التقارب للخوارزمیات المقترحة pdf created with pdffactory trial version www.pdffactory.com mailto:mahmood.abdulsattar@googlemail.com mailto:msc_eng_samerhussein@yahoo.com http://www.pdffactory.com http://www.pdffactory.com (microsoft word 103-109 \323\341\355\343) al-khwarizmi engineering journal,vol. 13, no. 1, p.p. preparation of light fuel fractions by thermal cracking reaction saleem department of chemical engineering/ email: (received 2 https://doi.org/10.22153/kej.2017.11.003 abstract this work deals with thermal cracking of heavy vacuum gas oil which produced from the top of vacuum distillation unit at aldura refinery, by continuous process. an experimental laboratory plant scale was constructed in laboratories of chemical engineerin the thermal cracking process was carried out at temperature ranges between 460 with liquid hourly space velocity (lhsv) equal to 15hr distilled by atmospheric distillation device according to astm d as a gasoline fraction and above 220 o c as light cycle oil (lco). fractionated to light fractions (gasoline, kerosene and gas oil) by atmospheric distillation device. (gasoline, kerosene and gas oil) were distilled by atmospheric distillation device in order to obtained distillation curve for these fractions. physical properties in order to studying the possibilities of industrial uses. obtained by this process equal to 82 wt. % keywords: light fuel, thermal cracking, heavy vacuum 1. introduction vacuum gas oil is a part of petroleum hydrocarbon heavy distillate family. distillation recovers gas oil from the residual oil; in a vacuum tower so that the boiling point temperature is reduced, this allows distillation at temperatures that are not possible in atmospheric distillation. the thermal cracking unit is consisting scission of the hydrocarbon c–c bonds present in the feedstock. it is occurring temperature is raised (400-900) o c to a point at which the bonds that hold a molecule together are broken. cracking reaction start to occur at a temperatures of about (315-370) o c, on the hydrocarbon nature of the material being cracked, feed stock type and product requirement. khwarizmi engineering journal,vol. 13, no. 1, p.p. 103109 (2017) light fuel fractions from heavy vacuum gas oil thermal cracking reaction saleem mohammed obyed engineering/ collage of engineering / al-nahrain university email:saleem_mo71@yahoo.com 23 may 2016; accepted 29 november 2016) https://doi.org/10.22153/kej.2017.11.003 this work deals with thermal cracking of heavy vacuum gas oil which produced from the top of vacuum dura refinery, by continuous process. an experimental laboratory plant scale was constructed in laboratories of chemical engineering department, al-nahrain university and baghdad university. the thermal cracking process was carried out at temperature ranges between 460-560oc and atmospheric pressure with liquid hourly space velocity (lhsv) equal to 15hr -1 .the liquid product from thermal cracking unit was distilled by atmospheric distillation device according to astm d-86 in order to achieve two fractions, below 220 c as light cycle oil (lco).the first fraction which was fractionated to light fractions (gasoline, kerosene and gas oil) by atmospheric distillation device. (gasoline, kerosene and gas oil) were distilled by atmospheric distillation device in order to obtained distillation physical properties were recorded for these cuts to compare it with standard in order to studying the possibilities of industrial uses. the maximum conversion of heavy vacuum gas oil was obtained by this process equal to 82 wt. % of feed at 540oc. heavy vacuum ,gas oil. gas oil is a part of petroleum family. vacuum distillation recovers gas oil from the residual oil; in a vacuum tower so that the boiling point temperature is reduced, this allows distillation at temperatures that are not possible in consisting of the c bonds present occurring when the c to a point at a molecule together cracking reaction start to occur at a , depending of the material being feed stock type and product treatment in any thermal process results in the formation of gases, gasoline distillate fractions (kerosene and gas oil residual fractions, and coke. the yield, relation between the reaction product's and the properties of these products depend on many factors, but the main role is played by the composition of the feed stock, the temperature, pressure and duration reaction. [1] the rate of a reaction grows with elevation of the feed stock boiling point. feed stock containing mainly alkanes is preferable for thermal cracking plants because they decompose more readily with the formation of target products such as gas, gasoline, and middle distillate, as the same time a little coke forms. the degree of conversion in the thermal cracking is characterized by the gasoline yield al-khwarizmi engineering journal heavy vacuum gas oil nahrain university this work deals with thermal cracking of heavy vacuum gas oil which produced from the top of vacuum dura refinery, by continuous process. an experimental laboratory plant scale was and baghdad university. c and atmospheric pressure al cracking unit was 86 in order to achieve two fractions, below 220 o c below 220 o c was fractionated to light fractions (gasoline, kerosene and gas oil) by atmospheric distillation device. the fractions (gasoline, kerosene and gas oil) were distilled by atmospheric distillation device in order to obtained distillation were recorded for these cuts to compare it with standard property test, the maximum conversion of heavy vacuum gas oil was treatment in any thermal process results in gasoline, middle distillate fractions (kerosene and gas oil), heavy the yield, relation between the reaction product's and the properties of these products depend on many factors, but the main role is played by the composition of the feed stock, the temperature, pressure and duration of the the rate of a reaction grows with elevation of the feed stock boiling point. feed stock containing mainly alkanes is preferable for thermal cracking plants because they decompose more readily with the formation of as gas, gasoline, and middle distillate, as the same time a little coke the degree of conversion in the thermal cracking is characterized by the gasoline yield saleem mohammed al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 103109 (2017) 104 relative to the feed stock. the degree of conversion is limited by the formation of coke and gas. the coke yield grows with increasing temperature and residence time of the stock in the reaction zone. [2]. elevation of the cracking temperature at a constant pressure and constant degree of conversion leads to an increase in the constant of light components and to a reduction in the yield of heavy fractions and coke. [3] the feed stock consists of a large number of individual componentsso, it is impossible to predict or follow the fate of each of these components under the action of high temperatures. the aim of this work study the thermal cracking reaction of heavy vacuum gas oil at a temperature ranges (460-560) o c and tested some major physical and chemical properties of light product fractions to compare it with standard property test, in order to studying the possibilities of industrial uses. 2. experimental work materials heavy vacuum gas oil which produced from top of vacuum distillation unit in al -dura refinery was used as feedstock in this study. the properties of heavy vacuum gas oil were determined by laboratory of al-dura refinery, as shown in table 1. table 1, physical and chemical properties of vacuum gas oil sample. characteristics value viscosity (40 0 c) 48 c.st flash point (open cup) 110 0 c ph 7 color brown melting point / freezing point >15 0 c initial boiling point and boiling range 306-532 0 c vapor pressure 0.01 kpa. 20 0c relative density 0.9 auto-ignition temperature >220 0 c specific gravity 0.91 3. the experimental work units the desired quantity of hvgo(6300 ml/hr.) pumped by dosing pump at the desired flow to the evaporator. in the evaporator the feed heated to 330oc, and then enters the reactor, its volume was (420 ml). the reactor temperature was measured by thermocouples. the product discharged to the condenser section, where the condensates are collected, for all runs in various operating temperature. the uncondensed gases are collected in gas collector. the duration time for each experiment was 30 minute. fig. (1) shows the fixed bed reactor unit where experiments which took place at temperature range 460-560oc and liquid hour space velocity 15hr-1. fig. (2) shows the distillation unit of cracking liquid products which were achieved in atmospheric distillation unit which consist of heater and condenser according to (astm d86) for light cuts. fig. 1. photograph picture of the fixed bed reactor unit. fig. 2. astm d-86 distillation unit. saleem mohammed al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 103109 (2017) 105 fig. 3. schematic flow diagram of laboratory continuous cracking unit. 1-feed reservoir: 2dosing pump; 3-preheater; 4one way valve; 5reactor system; 6temperature controller; 7condenser; 8flow meter; 9control valves; 10separator; 11cooling machine. 4. results and discussion 4.1. effect of temperature on thermal cracking reaction the effect of temperature ranges (460560)°c on the heavy vacuum gas oil conversion and the yield of gases, gasoline, light cycle oil and coke that were studied at constant liquid hour space velocity (lhsv)15hr 1 were shown in table 2. table 2, effect of temperature on liquid products from thermal cracking of heavy vacuum gas oil. 560 540 500 460 temperature o c 15 15 15 15 liquid hour space velocity hr -1 82 81 77.5 75.6 conversion wt.% 52 52 51 49 gasoline wt.% 18 19 22.5 24.4 light cycle oil (lco)wt.% 70 71 73.5 73.4 total liquid product wt.% 3.4 3 2.6 2 coke wt.% 24 22 18 15 gases wt.% 1.6 2 5.9 5.4 residue wt.% 1 2 3.5 4.2 losses figure 4 shows the effect of temperature ranges (460-560) ° c on the heavy vacuum gas oil conversion by thermal cracking. as shown from this figure the heavy vacuum gas oil conversion increases with increasing temperature. this may be attributed to; the increase of temperature which accelerates intermolecular motions assists the transformations of the reactants into new compounds and thus enhances the rate of chemical reaction, as mentioned also by decroopcq [4]. fig. 4. effect of temperature on conversion of thermal cracking of heavy vacuum gas oil. saleem mohammed al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 103109 (2017) 106 fig. (5) and fig. (6) shows the yield of gases and gasoline respectively. the gasoline yield is chiefly affected by gas formation. the increasing in the temperature reaction firstly increases the gasoline yield, then higher temperature gives lower gasoline yield and higher gases yield, this due to cracking gasoline itself to lighter fractions so the best temperature of thermal cracking of hvgo is 540 °c for this reason. fig. 5. effect of temperature on gases yield by thermal cracking of hvgo. fig. 6 .effect of temperature on gasoline yield by thermal cracking of hvgo. fig.(7) and fig. (8) shows that the yield of light cycle oil (lco) decreases by temperature increasing and slightly increases in coke yield respectively. fig. 7. effect of temperature on light cycle oil yield by thermal cracking of hvgo. fig. 8. effect of temperature on coke yield by thermal cracking of hvgo. fig. (9) shows the thermal cracking products distribution at different temperatures ranges (460 – 560) ºc and constant lhsv. fig. 9. effect of temperature on thermal cracking products yield from hvgo. the increasing in the reaction temperature firstly increases the gasoline yield then higher 560 °c temperature gives lower gasoline yield and higher gases yield, (figures 6 and figure 5). since the conversion increases with temperature increasing, the light cycle oil decreases by temperature increasing at constant lhsv as saleem mohammed al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 103109 (2017) 107 shown from figure 7. and slightly decreases in coke yield (figure 8). clear pictures for thermal cracking products distribution at different temperatures ranges 480 540 ºc and constant lhsv were presented at figure 9. the above results agreed with those obtained by reagan [5]. 4.2. the atmospheric distillation results 4.2.1. heavy vacuum gas oil the results of atmospheric distillation for heavy vacuum gas oil and true boiling point distillation (tbp)were tabulated in table 3 which used to calculate some physical properties after calculate the mean average boiling point . table 3 results of astmd-86 and tbp distillation for heavy vacuum gas oil. 4.2.2. light fractions the results of atmospheric distillation for light fractions (gasoline, kerosene and gas oil) according to astm–d86were tabulated in table 4which used to calculate some physical properties after calculate the mean average boiling point for any fraction. table 4, results of astm d-86 distillation for (gasoline, kerosene and gas oil) astm d-8 ( o c ) gas oil astm d-86 ( o c ) kerosen astm d-86 ( o c ) gasoline volume % 195 135 44 initial boiling point 215 170 57 5 230 178 63 10 247 176 73 20 259 190 82 30 262 197 92 40 279 205 103 50 289 210 116 60 299 216 130 70 309 228 150 80 329 241 180 90 258 195 95 t.b.p ( o c ) t.b.p ( o r ) astm d-86 ( o r ) astm d-86 ( o c ) volume% 63 606 654 90 0 253 948 942 250 5 259 959 978 270 10 270 978 989 276 15 280 996 996 280 20 296 1040 1032 300 25 304 1040 1043 306 30 310 1051 1050 310 35 318 1065 1061 316 40 322 1073 1068 320 45 327 1080 1072 322 50 332 1090 1079 326 55 339 1103 1086 330 60 342 1107 1090 332 65 348 1118 1097 336 70 352 1127 1097 336 75 358 1137 1100 338 80 362 1145 1111 344 85 365 1150 1122 350 90 383 1181 1149 365 95 390 1194 1158 370 100 saleem mohammed al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 103109 (2017) 108 5. the physical and chemical properties of fractions table 5 shows the properties for light fractionswhich were produced from distillation of liquid thermal cracking for heavy vacuum gas oil, to compared it with standard property for the same fraction, in order to possibility commercial uses these fractions. table 5, the results of physical properties for (gasoline, kerosene and gas oil). property type of fraction which were produced from liquid thermal cracking of vgo standard property for fraction gasoline kerosene gas oil gasoline kerosene gasoil specific gravity. 0.77 0.81 0.85 0.72-0.77 0.77-0.82 0.82-0.86 api gravity. 85 48 44 50-60 40-50 35-45 �� (ºr) 640 870 975 k-index 12 12.2 12.3 11-13 11-13 11-13 molecular weight. 93 167 214 115 170 225 flash point(ºk) 300 310 325 min.327 min.315 min.305 diesel index. 90 61 73 aniline point (ºc) 67 70 72 60 65 70 viscosity at 100 ºf (cst.) 0.5139 1.3238 2.511 0.6 1.6 max.5.6 refractive index experimental 1.4104 1.435 1.4456 empirical 1.4395 1.456 1.4877 pour point (ºk) 165 246 218 max.264 min.220 min.160 smoke point (mm) 23 min.21 6. conclusion 1it was concluded that the possibility produced of light fractions (gasoline, kerosene, gas oil) from heavy vacuum gas oil by thermal cracking process at different temperatures and constant space velocity at atmospheric pressure. 2it was concluded that the heavy vacuum gas oil conversion increases with increasing the temperatures of thermal cracking. 3possibilty uses these light fractions for internal combustion engine or for domestic usesand diesel fuel. 7references [1] alkilani.a. haitham m. s. taher a. alsahhaf "fundamental of petroleum refining", (2010) [2] pillion l. z, interfacial properties of petroleum products, by tayler& francis group, llc, (2005). [3] levenspiel, o., "chemical reaction engineering" john wiley and sons inc.3ed (1999). [4] denial decroopcq “catalytic cracking of heavy petroleum fractions”, paris (1984). [5] reagan, w.j., u.s. department of energy, pittsburgh energy technology center, liquefaction conttractors' review, conference proceedings, september, 1992, pittsburgh, pa., 261-290. [6] speight, j.g. "the chemistry and technology of petroleum,",3rd ed. marcel dekker, new york (1999). [7] bhaskararao b.k. "modern petroleum refining processes" 4th ed. indian institute of technology. (2004) [8] speight, j.g. "hand book of petroleum product analysis", usa. (2002) [9] alan g. lucas "modern petroleum technology", vol.2 downstream new york 2001. [10] lappas, a. 2 nd european summer school on renewable motor fuels warsaw, poland (2007). )2017( 103-109، ?<+3 1، ا1>&د13&3.0 ا9:1ارز,6 ا451&/'3 ا1*0., /.',+*& ()'& 109 ,v زtu اes1ز اg>1ا6r ا9p n'fq1ا/n)e>i 3o اg'klm1 اg+1اري ef, g'h+i3طc و9aد @<'< &'() &*+, -'./ ��� ا ����� /ا ��������� / �ا ���� و� ا �������� � saleem_mo71@yahoo.com ���� و�� ا��� �:ا 3?w:1ا ول ھ�ا ���8 رة، و�� ا 6)ء ا ��4ي �� و�3ة ا �,��2 ا *�ا(� �1 �0* ة ا � ا �ي ���. � ا -,�+*�ا(ا )�' ا & ز ا ����� ا "�اري ا �"!� ���ة ;���� �3اري ����8 ط��9��.���� ��>��4 ;� ;���0 و;�*�=�>� �����6; ��? ���ات ��� ا ����� ا ����=� �1 �1 ��� ��� ا ����� و�� ٥٦٠o�3٤٦٠ارة ;��اوح ��b �1 ���ل در�� و�� أ���' ����8 ا ����� ا "�اري .b&�اد c 46ي ا i&j دي وا ��8� اj* �8 ا�� k���? )lhsv ( وي �;١٥ � �� . �;? ا ���. �� و�3ة ا ����� ا "�اري 4b +;,��2 ا �� �*m4ا�� �� astm d-86ط� �� ز ا �,��2 ا 46ي ط�, م٢٢٠ ;"'، �,���2أ�+ ;",�9 ° �2,� >*m4b و41ق ��م���٢٢٠) ° >*m4b� ز� *�*q اsول ا �ي � ن ;"' ء;,��2 ا lco.( �;(6( ��ور م٢٢٠ ° t إkط ز ا �,��2 ا 46ي �8 ط��9) ا ��)�� وا ���و��� وز�' ا & ز(ا =*�*� ا �,��. v �ا ��)�� وا ���و��� ( �, طkا �,��2,; �2 ;�� �ه ا �ي ;� ا "40ل t�"��>��8 ا �,��2 ر�� �� wqل �� ز ا �,��2 ا 46ي �� أ�+ ) وز�' ا & ز� kط ب ���ل در�� ا &�� ن ��ه ا �,�" v وذ kط �3 ب .ا �,[? ت �b\ ا =0*m4ا� وا ��? ا ��84، �,�2 ا ��4\، �,�2 ا�����s، ا 4زندر�� ا &�� ن، ��i�4 (�-+ ا ����ا *�)� ?�� وا ���� ن، ا 4زن ا 6)�[�q� �2 ا,� (v وذ k� �� ت �, ر�*m4ا� ا��� 6 ر�� ا ,���=�ا� ت ا �0 ��8ا��� أ�+ در ا �� ت ا�� ;� ا "40ل t�8 .� إ�� 4زن ٨٢إ t �0+�� ھ�ه ا ����� �أ�t0 ��ر �� ;"4�+ ز�' ا & ز ا -,�+ ا *�ا(b . ٪��8م.٥٤٠ ° al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 7, no. 1, pp 13 21 (2011) noise removal of ecg signal using recursive least square algorithms noor k. muhsin department of biomedical engineering/ al-khwarizmi college of engineering/ university of baghdad email: noorbmemsc81@yahoo.com (received 11 may 2010; accepted 17 february 2011) abstract this paper shows an approach for electromyography (ecg) signal processing based on linear and nonlinear adaptive filtering using recursive least square (rls) algorithm to remove two kinds of noise that affected the ecg signal. these are the high frequency noise (hfn) and low frequency noise (lfn). simulation is performed in matlab. the ecg, hfn and lfn signals used in this study were downloaded from ftp://ftp.ieee.org/uploads/press/rangayyan/, and then the filtering process was obtained by using adaptive finite impulse response (fir) that illustrated better results than infinite impulse response (iir) filters did. keywords: adaptive filters, rls algorithms, noise, ecg signals, signal processing. 1. introduction adaptive digital filters are successfully used in many practical systems such as echo, noise canceling, line enhancers, speech coding, and equalizers etc. it operates by adjusting its coefficients in response to its input so as to effectively process that input. thus the filter coefficients are a function of the actual data they process. rls adaptive algorithms operate by adjusting the filter coefficient vector so as to converge to the optimum wiener coefficient vector. this is one of the primary advantages of an adaptive filter. another primary advantage of adaptive filters is that they can be used in nonstationary environments. since an adaptive filter is continuously self-designing, it can adapt to statistical changes in the data. [1] kevin m. buckley illustrated the application of filtering to biomedical signals such as ecg, in fetal heart monitor to remove power-line (50 or 60 hz) interference noise. [1] kiyoshi nishikawa and hitoshi kiya proposed a method for increasing the throughput of recursive least squares (rls) adaptive filters when only a few processing elements (pes) are available.[3] this paper shows method to remove two types of noise that corrupted the ecg signal, which are the hfn and lfn downloaded as hfn-ecg and lfn-ecg from internet with sampling frequency of 1000 hz.[2] the rls algorithm is used because it has much faster convergence rate than the least mean square (lms) algorithm. 2. adaptive filter for noise cancelling adaptive signal processing system has been used in several biomedical applications. the rls learning algorithm that are used in both linear and nonlinear adaptive filters. when the input process of an adaptive system is (quasi-) stationary, the best steady state performance results from slow adaptation. however, when the input statistics are time-variant (nonstationary), the best performance is obtained by a compromise between fast adaptation (necessary to track variations in the input process) and slow adaptation (necessary to limit the noise in the adaptive process). the lms adaptation algorithm is a simple and efficient this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ noor k. muhsin al-khwarizmi engineering journal, vol. 7, no. 1, pp 13 21 (2011) approach for adaptive noise canceling (anc); however, it is not appropriate for fast-varying signals due to its slow convergence, and due to the difficulty in selecting the correct value for the step size µ. an alternative approach based on the exact minimization of the least-squares criterion is the rls method .the rls algorithm has been widely used in real-time system identification and noise cancellation because of its fast convergence, which is about an order of magnitude higher than that of the lms method. an important feature of the rls algorithm is that it utilizes information contained in the input data, and extends it back to the instant of time when the algorithm was initiated. given the leastsquares estimate of the tap-weight vector of the filter at time n 1, the updated estimate of the vector at time n is computed upon the arrival of new data.[4]. fig. 1. general structure of the adaptive rls filter[2] in the derivation of the rls algorithm, the instantaneous error e [n] can be calculated from the following equation: e[n] = x[n] h′[n] y[n] = x[n] y′[n] h[n] …(1) where y[n] is the output of the filter, y′[n] is the output of the filter vector, and h[n] is the filter parameter, h′[n] is the filter parameter vector. the rls algorithm considers all the available data for determining the filter parameters. the filter should be optimum with respect to all the available data in certain sense. minimizes the cost function ][][ 2 0 ken n k kn    …(2) with respect to the filter parameter vector             ][ ][ ][ ][ 1 1 0 nh nh nh nh m …(3) where λ is the weighing factor known as the forgetting factor, recent data is given more weightage, for stationary case λ = 1 can be taken, λ=0.99 is effective in tracking local nonstationarity, the minimization problem is minimize 2' 0 ])[][][(][ nhkykxn n k kn     with respect to h[n] the minimum is given by 0 )( )(    nh n 0])[][][][][(2 ' 0    nhkykykykx n k kn …(4) ][][][][][ 0 1 ' 0 kykxkykynh n k kn n k kn               …(5) let us define ][][][ ' 0 kykynr n k kn yy      …(6) which is an estimator for the autocorrelation matrix ryy . similarity ][][][ 0 kykxnr n k kn xy     …(7) is the estimator for the crosscorrelation vector ][nrxy  hence   ][][][ 1 nrnrnh xyxy    …(8) is the matrix inversion is involved which makes the direct solution difficult. we look forward for a recursive solution.[4] 2.1. recursive representation of ][nryy  ][nryy  can be written as follows this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ noor k. muhsin al-khwarizmi engineering journal, vol. 7, no. 1, pp 13 21 (2011) 15 ][][][][][ '' 1 0 nynykykynr n k kn yy       ][][]1[ ][][][][ ' '' 1 0 1 nynynr nynykyky yy n k kn          …(9) this shows that the autocorrelation matrix can be recursively computed from its previous values and the present data vector.[4] similarly ][][]1[][ nynxnrnr xyxy        ][][][]1[ ][][][ 1' 1 nrnynynr nrnrnh xyxy xyyy        …(10) for the matrix inversion above the matrix inversion lemma will be useful. 2.2. matrix inversion lemma if a, b, c and d are matrices of proper orders, a and c nonsingular   11111 )(   dacbdabaabcda …(11) taking ],1[  nra yy   ],[nyb  c=1 and ][' nyd  we will have   ]1[][1][]]1[[ 1 ][][]1[ 1 ]1[ 1 ][ 1' 1 1'1 11             nrnynynrnynynr nrnr yyyyyy yyyy                 ][]1[][ ]1[][][]1[ ]1[ 1 1' 1'1 1 nynrny nrnynynr nr yy yyyy yy     …(12) rename p[n]= ][1 nryy  . then ])1[][][]1[( 1 p[n] '  npnynknp  …(13) where k[n] is called the "gain vector" and given by ][]1[][ ][]1[ ][ ' nynpny nynp nk    …(14) k[n] important to interpret adaptation is also related to the current data vector y[n] by k[n]=p[n]y[n] to establish the above relation consider p[n] =  1 1(p[n −1] − k[n]y′[n]p[n −1]) …(15) multiplying by λ and post-multiplying by y[n] and simplifying we get ][])1[][][]1[(][][ ' nynpnynknpnynp  =p[n-1]y[n]-k[n]y'[n]p[n-1]y[n] =λk[n] …(16) therefore ][][][ ^1^ nrnrnh xyyy        =p[n](λ nr xy [ ^ -1]+x[n]y[n]) =λp[n] nr xy [ ^ -1]+x[n]p[n]y[n] n]x[n]p[n]y[+]1[r1]]-[n]p[nk[n]y'-1]-[p[n 1 = ^ xy n   = h[n-1]+k[n]y'[n]h[n-1]+x[n]k[n] =h[n-1]+k[n](x[n]-y'[n]h[n-1]) …(17) 2.3. rls algorithm operation the rls algorithm can be motivated and derived as the exact solution to a well-defined estimation problem with a least-squares cost function.[5] the rls algorithm operation was: for 1 to n = final 1. get x[n], y[n] 2. get e[n] = x[n] − h′[n −1]y[n] 3. calculate gain vector ][]1[][ ][]1[ ][ ' nynpny nynp nk     4. update the filter parameters h[n] = h[n −1] + k[n]e[n] 5. update the p matrix 1])-[n]p[n[n]y-( 1 p[n] 'knp   end this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ noor k. muhsin al-khwarizmi engineering journal, vol. 7, no. 1, pp 13 21 (2011) fig.2. block diagram of the proposed system. 3. methodology from the following bloke diagram, this section is divided in to three steps as follows: 3.1. 1st step noisy ecg data acquisition the ecg is the electrical manifestation of the contractile activity of the heart, and can be recorded fairly easily with surface electrodes on the limbs or chest. the corrupted ecg signals with hfn and lfn are a real data down loaded from internet[1], these contaminated ecg of 500 µ sec (2000 samples) data length with sampling frequency of 1000hz. 3.2. 2nd step filteration process the noisy ecg signals in this step were passing through the adaptive fir and iir filters, the adaptation process were done using rls algorithm to remove the hfn and lfn from the ecg signals. the selected parameters were illustrated in table 1: table 1, parameters of the proposed system. fir iir system order 5 10 λ 0.999 0.9995 the selected order for the fir type is half of the iir filter and illustrated more pleasant results with more sharpness compared with the iir filter that required higher order to illustrated a familiar results. the weighting factor λ (also known as the forgetting factor) with 0 < λ < 1. the values of λn-i < 1 give more “weight” to the more recent error values. such weighting is desired in the case of nonstationary data, where changes in the signal statistics make the inclusion of past data less appropriate [6]. so that the smaller forgetting factor λ give an indication of the smaller contribution of previous samples. this makes the filter more sensitive to recent samples, which means more fluctuations in the filter coefficients. the λ = 1 case is referred to as the growing window rls algorithm.[7] 3.3. results and discussion a. noise removal to verify the algorithm suggested in this paper, the ecg signals were filtered and evaluated the overall error of the signal and the optimal filter order. in this paper, matlab was used to estimate the performance of the proposed filters, and experimented with two kinds of filters. the mean  x and standard std deviation were calculated. the mean which is the average value of a signal. it is found by adding all of the samples together, and divide by n. it looks like this in mathematical      1 0 1 n i ixn x …(18) std: standard deviation the standard deviation s of a data vector x: 2/1 1 0 2 1                   n i i x n std x …(19) where     n i ixn x 1 1 this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ noor k. muhsin al-khwarizmi engineering journal, vol. 7, no. 1, pp 13 21 (2011) 17 and is the n number of elements in the sample. the two forms of the equation differ only in n-1 versus n in the divisor. the results are shown in table (2): table 2, fir and iir filter results. hfn removal lfn removal output (rls) output (rls) output (rls) output (rls) fir iir fir iir mean desired signal -0.528 -0.176 -0.798 -0.435 output signal -0.489 0.023 -0.713 -0.034 std desired signal 0.774 0.723 0.785 0.772 output signal 0.776 0.536 0.847 0.787 from the above table the means of both fir filter causes to remove the hfn and lfn is smaller value and approach to the desired values of the output as shown in figure 3 and 4 respectively. while iir filter means of the output are small values and less than the desired signals values as shown in figure 5 and 6. to compare between the standard deviation of the two outputs the results shown that std of fir output of hfn is approximately similar to std of the desired signal and less than of iir output std but approximately similar to std of desired signal that mean that the deviation of the results from the true curve is smaller in case of fir filters to remove both noises than the iir filters. fig.3. fir filter results to remove hfn. fig.4. fir filter results to remove lfn. 0 20 40 60 80 100 120 140 160 180 200 -2.5 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 2.5 system output samples t ru e a n d e s ti m a te d o u tp u t desired signal output signal 0 20 40 60 80 100 120 140 160 180 200 -3 -2 -1 0 1 2 3 4 system output samples t ru e a n d e s ti m a te d o u tp u t 0 20 40 60 80 100 120 140 160 180 200 -2 -1 0 1 2 3 4 system output samples t ru e a n d e s ti m a te d o u tp u t this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ noor k. muhsin al-khwarizmi engineering journal, vol. 7, no. 1, pp 13 21 (2011) fig.5. iir filter results to remove hfn. fig.6. iir filter results to remove lfn. b. error calculations the error curves were calculated as and ploted as shown in figures 6,7,8 and 9, respectively. (the logarithmic scale is used to display better the minor differences between the spectrograms.) it is seen that the frequency components of the hfn have been suppressed by using fir filter rather than the iir filter according to the following calculations of mean and std that shown in table 3. table 3, error curves calculations. hfn removal lfn removal error (rls) error (rls) error (rls) error (rls) fir iir fir iir mean -0.547 -0.1283 -0.0592 -0.4115 std 0.2879 0.4973 0.2609 0.6174 fig.7. error curve of hfn removal using fir filter. fig.8. error curve of hfn removal using iir filter. fig.9. error curve of lfn removal using fir filter. 0 20 40 60 80 100 120 140 160 180 200 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 system output samples t ru e an d es tim at ed o ut pu t 0 20 40 60 80 100 120 140 160 180 200 10 -4 10 -3 10 -2 10 -1 10 0 10 1 error curve e rro r v al ue 0 20 40 60 80 100 120 140 160 180 200 10 -4 10 -3 10 -2 10 -1 10 0 10 1 error curve samples e rr or v al ue 0 20 40 60 80 100 120 140 160 180 200 10 -4 10 -3 10 -2 10 -1 10 0 10 1 error curve samples e rr or v al ue 0 20 40 60 80 100 120 140 160 180 200 10 -4 10 -3 10 -2 10 -1 10 0 10 1 error curve samples e rr or v al ue this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ noor k. muhsin al-khwarizmi engineering journal, vol. 7, no. 1, pp 13 21 (2011) fig.10. error curve of lfn removal using iir filter. c. comparison of the filter weights and estimated weights according to the order of the filter the following figures shows a comparison between the filter weights and estimated weights for both fir and iir filters. as illustrated in section 3.1 and table 1 the fir filter order (5) while iir filter order (10) because fir filter output is calculated using the current and past input, but not previous values of the output and produce more placental results at the selected order but iir filters are recursive filters that use the surrounding input and previous output values together and the selected order introduce good results. fig.11. comparison of the fir filter weights and estimated weights (hfn removal). fig.12. comparison of the iir filter weights and estimated weights (hfn removal). fig.13. comparison of the fir filter weights and estimated weights (lfn removal). fig.14. comparison of the iir filter weights and estimated weights (lfn removal). 4. conclusions the ecg is perhaps the most commonly known, recognized, and used biomedical signal that corrupted with several types of noise such as hfn and lfn. excessive filtering results in a distorted signal were evaluated the performance of the rls algorithm for these signals. this paper can be illustrated that the means of both fir filter causes to remove the hfn and lfn is smaller value and approach to the desired values of the output, while iir filter means of the output are small values and less than the desired 1 1.5 2 2.5 3 3.5 4 4.5 5 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1 samples w ei gh ts v al ue comparison of the filter weights and estimated weights filter weights estimated filter weights 1 2 3 4 5 6 7 8 9 10 -0.15 -0.1 -0.05 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 comparison of the filter weights and estimated weights filter weights estimated filter weights 1 1.5 2 2.5 3 3.5 4 4.5 5 -1 -0.5 0 0.5 1 1.5 2 comparison of the filter weights and estimated weights filter weights estimated filter weights 1 2 3 4 5 6 7 8 9 10 -0.05 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 comparison of the filter weights and estimated weights filter weights estimated filter weights this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ noor k. muhsin al-khwarizmi engineering journal, vol. 7, no. 1, pp 13 21 (2011) 20 signals values, but the standard deviation of the two outputs (fir output of hfn) is approximately similar to std of the desired signal and less than of iir output std which is similar to std of desired signal that mean that the deviation of the results from the true curve is smaller in case of fir filters to remove both noises than the iir filters. the fir adaptive filter using rls algorithm is illustrated more perfect results compared with iir filters. notation s[n] desired signal n[n] interference signal x[n] the input of the adaptive filter e[n] error signal y[n] the output of the adaptive filter y'[n] the output of the adaptive filter vector h'[n] filter parameter vector h[n] filter parameter n,k,m length of the signal k[n] gain vector a,b,c,d matrices of proper order ][nryy  an estimator for the autocorrelation matrix an estimator for the autocorrelation matrix p[n] inversion of an estimator for the autocorrelation matrix nr xy [ ^ ] an estimator for the autocorrelation vector greek letters λ the forgetting factor δ positive number ε[n] cost function 5. references [1]. kevin buckley., " ece5251 biomedical signal processing", 2009 [2]. kiyoshi nishikawa and hitoshi kiya, "noval implementation technique of rls algorithm for improving throughtput of adaptive filters, 1999. [3]. ftp://ftp.ieee.org/uploads/press/rangayyan/ [4]. p.k. bora, "statistical signal processing", john wiley and sons, inc., 1996. [5]. ali h. sayed, "adaptive filters",2008 [6]. rangarai m. rangayyan., "biomedical signal analysis a case-stady approach", john wiley and sons, inc., 2002. [7]. hayes, monson h., “statistical digital signal processing and modeling", john wiley and sons, inc., 1996. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ 21 ، صفحة1، العدد 7مجلة الخوارزمي الھندسیة المجلد نور كمال محسن 13 )2011( 21 َتستعمُل أقّل تكراریًة الخوارزمیاِت المرّبعِةإزالة ضوضاِء التي نور كمال محسن جامعة بغداد/ كلیة الھندسھ الخوارزمي/ قسم ھندسة الطب الحیاتي noorbmemsc81@yahoo.com: االلكتروني البرید الخالصة لّ ة أق تعمُل خوارزمی ذي َیس يِّ ال ِي والخط ِي الالخّط یح التكیف ى الَتْرش تندة عل ِع ھذا البحث یبحث نظرًة لمعالجِة إشارات تخطیط القلب مس ًة المرب تكراری اءَ الي و ضوض ذب الع اَء التذب واطئ إلزالة إثنان ِمْن أنواِع الضوضاِء الذي المؤثره على إشارِة تخطیط القلب و المتمثلھ بضوض ذب ال ة . التذب اة ُمَؤّدی المحاك ك عملی د ذل ِت ، وبع ْن اإلنترن ْت ِم ِة ُحّمل ذه الدراس ي ھ تعملْھ ف واطئَ المس ذب ال اَء التذب الي و ضوض ذب الع تعمال بأستخدام ال ضوضاَء التذب یح بإس ة الَتْرش !!!ز الالنھائياستجابة الحافالذي صّوَر َنتاِئَج افضل ِمْن مرشحاِت استجابة الحافز المحدود !! this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ 73-78 al-khwarizmi engineering journal,vol. 1 a comparison between recursive least-squares (e variation department of information and communication email: (received abstract in order to select the optimal tracking of fast time var this paper focuses on the recursive least reaches the conclusion that e-rls is more feasible according to the tracking performance and mean square error one time (send/receive) reach to 100 times keywords: rls algorithm, e-rls algorithm, rayleigh fading channels 1. introduction data transmission over mobile communication channels suffers from fading. the amplitude of transmitted signal will changes randomly according to affect of frequency flat fading important to track variations of the amplitude to detect transmitted symbols optimally nonexistence of the direct line of made rayleigh fading supposition, i.e., the amplitude (received amplitude) sequence with a rayleigh density. the fading rate of the received signal amplitude is by the doppler bandwidth, which in turn is to the speed of mobile or receiver transmission frequency. this fading rate treated through design of powerful subsequently, in the fast single or multipath fading channels, cannot be neglect affected part the amplitude of the signal over a symbol period the sampling frequency of the received signal over slow fading channels is the nyquist frequency of the transmitted signal sampling rate is twice transmitted signal bandwidth, that means the effects of varying rayleigh fading channel be huge on the khwarizmi engineering journal,vol. 12, no. 1, p.p. 7378 (201 comparison between recursive least-squares (rls) and extended quares (e-rls) for tracking multiple fast time variation rayleigh fading channel ali salah mahdi and communication engineering/ al-khawarizmi college of engineering university of baghdad email: ali_info27@kecbu.uobaghdad.edu.iq (received 25 may 2015; accepted 11 october 2015) in order to select the optimal tracking of fast time variation of multipath fast time variation rayleigh fading channel recursive least-squares (rls) and extended recursive least-square is more feasible according to the comparison output of the mean square error over five fast time variation of rayleigh fading reach to 100 times to make sure from efficiency of these algorithms. rls algorithm, rayleigh fading channels. communication the amplitude of signal will changes randomly of frequency flat fading. it is the amplitude to detect transmitted symbols optimally. in the direct line of sight, is often , i.e., the faded is a random the fading rate is administered in turn is related or receiver and the fading rate must be powerful receivers. single or multipath not be neglect affected part of over a symbol period. the received signal is the nyquist signal and this transmitted signal that means the effects of the fast time be huge on the (faded) signal since the bandwidth greater than the bandwidth [1,2,3,4], so it efficient channel estimation to get the original data, here we are compared the performance of two algorithms, recursive least extended recursive least algorithms to show which one has a good to track fast time variation of rayleigh fading channels, to decrease the faded signal at the receiver recent years, the comparison tracking performances for lms and recursive least-squ much have been described such as in lms algorithm shows performance than the rls algorithm because the lms algorithm is model independent, w rls algorithm is model dependent. the remainder of this follows. we introduced section 2. in section 3, we present model of rls and e-rls algorithms section 4, we compared rls and e-rls by computer simulation. section 5 concludes the paper. al-khwarizmi engineering journal (2016) quares (rls) and extended multiple fast time khawarizmi college of engineering/ fast time variation rayleigh fading channel, squares (e-rls) algorithms and the simulation program from rayleigh fading channels and more than received signal have a than the transmitted data [1,2,3,4], so it must be there an estimation to get the original ere we are compared the performance of two algorithms, recursive least-squares (rls) and recursive least-squares (e-rls) to show which one has a good ability time variation of rayleigh fading the negative effect on the at the receiver. by pointing to the the comparison assessment of the for the least mean square squares rls algorithms been described such as in [5]–[8]. the shows a well tracking the rls algorithm because the lms algorithm is model independent, while the rls algorithm is model dependent. the remainder of this paper is prepared as the channel model in , we present mathematical rls algorithms. next, in the performance of the rls by computer simulation. section ali salah mahdi al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 7378 (2016) 74 2. channel model the impulse response of a multipath fading channel can be describe as ℎ��� = ∑ �� � � ����� ��� − ��� …(1) where �, �� , ����� , are respectively the channel length, path loss and rayleigh fading sequence of the �-th reflector groups, and �� are the groups delay. in this event, for each �, assumed the amplitude |����| have a rayleigh distribution as shown below [9]: �|����� |�|����� |� = |����� | ��|����� |�/�, |����� | ≥ 0 …(2) whereas, the phase ( )x n∠ is uniformly distributed (assumed) with in�−�, � : � ! ( )kx n∠ " = � �# , −� ≤ ( )kx n∠ ≤ � …(3) also, the auto-correlation function of the ����� sequence, now considered as a random process, is modeled as a zeroth-order bessel function of the first kind [9], i.e., %��� ≜ ' ����� ���� − �(� = ℐ(�2��+,-�(�, �( = ⋯ , −1,0,1,… …(4) where ,is the time sampling of the sequence �����, �+ is the maximum doppler frequency of the rayleigh fading channel, and the function ℐ(�·� is determined by : ℐ(�3� ≜ � # 4 cos �3 sin :�;:# < …(5) the doppler frequency �+ is the product of carrier frequency �= by speed of mobile users (receiver),>, over to speed of light as given below: �+ = ?@a = …(6) where b = 3 ∗ 10e f g⁄ . here, figure (1) show sequence magnitude and phase of rayleigh fading channel at �+ = 100 ij , ,= 1k10�lg, and number of channel samples = 200 samples. fig .1. sequence magnitude and phase of rayleigh channel at mn = opp qr . 3. mathematical model for tracking fast time variation of rayleigh fading channel here, we have explained the mathematical model of two algorithms as below [9]: a. tracking fast time variation of rayleigh fading channel via rls algorithm as given in equations below: st = st�� + vwx⍺z[wx\[∗ �]vwx\[z[wx\[∗ �;�^� − _tst�� …(7) t̀ = a�� b t̀�� − vwxz[wx\[∗\[z[wx �]vwx\[z[wx\[∗ c …(8) b . tracking fast time variation of rayleigh fading channel via e-rls algorithm as given in equations below : st = ⍺st�� + vwx⍺z[wx\[∗ �]vwx\[z[wx\[∗ �;�^� − _tst�� …(9) t̀ = a��|⍺|� b t̀�� − vwxz[wx\[∗\[z[wx �]vwx\[z[wx\[∗ c + de …(10) where st : weight vector. ⍺ : some scalar value |⍺| ≤ 1. a: some scalar value1 ≪ a ≤ 1. ali salah mahdi al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 7378 (2016) 75 t̀: covariance matrix. _t: input vector d: a constant multiple of the identity matrix e, where is more supposed to be less than unit magnitude in order to ensure the stability of the model. and the measurements ;�^� satisfy ;�^� = _tstg + >�^� …(11) st]�g = ⍺stg + �t …(12) where stg: unknown weight vector. >�^�: white noise measurement with unit variance. �t: disturbance. 4. simulation result in this simulation program, we consider the channels is multipath rayleigh fading and fast time variation with length 5 taps (number of simulated channels), doppler frequency �+ = 100hz, sampling frequency 1.25mhz, number of samples for each channel equal to 1000 samples. before displaying the results of simulation, we first describe the simulated algorithms parameters in table (1). table 1, simulation parameters. parameters specifications all initial values zero scalar value a 0.995 scalar value ⍺ 0.95 constant value d 0.1 number of experiments 100 figure (2), it is explained the magnitude for the 1st tap among five channels, it is illustrate three lines as described in top left of each figure. furthermore the difference between performance of rls and e-rls algorithms to track fast time variation of the rayleigh channel from start to end clearly appeared in figure (2), that means, e-rls algorithm has a good ability to track fast variation than rls algorithm. fig. 2. tracking performance of rls and e-rls algorithms for rayleigh channel 1. as well as, we explained tracking performance of each algorithm for all other channels as shown in figure (3), figure (4), figure (5), and figure (6), still e-rls superiorly on rls algorithm. fig. 3. tracking performance of rls and e-rls algorithms for rayleigh channel 2. ali salah mahdi al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 7378 (2016) 76 fig. 4. tracking performance of rls and e-rls algorithms for rayleigh channel 3. fig. 5. tracking performance of rls and e-rls algorithms for rayleigh channel 4. fig. 6. tracking performance of rls and e-rls algorithms for rayleigh channel 5. table 2 shows comparison between the mean square error mse values (selected randomly) for the recursive least-squares (rls) and extended recursive least-squares (e-rls) algorithms and the difference it is clearly appeared, mse of the e-rls (blue line) nearest to zero level than mse of the rls (black line). table 2, the comparison between mean square error (mse) of rls values and e-rls values. mse sample number mserls value mse e-rls value smaller value 20 6.1479 3.5628 e-rls 200 15.0826 4.3558 e-rls 500 16.5332 4.0328 e-rls 800 16.9514 2.6490 e-rls 1000 17.2023 3.3763 e-rls figure (7) described mean square error (mse) for each algorithm. the blue line represent mse of e-rls algorithm, and it is nearest to zero level than red line (mse of rls). naturally after the results that appeared in figure (3,4), the error ratio for e-rls should be less than the error ratio of rls algorithm, as shown in the mention figure. fig. 7.mean square error (mse) of rls and erls algorithms. 5. conclusion in this paper, we have compared two blind algorithms recursive least-squares (rls) and extended recursive least-squares (e-rls), ali salah mahdi al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 7378 (2016) 77 adaptive algorithms mean that, these algorithms try to estimate the channel without need any knowledge at the receiver (blindly). output figures (2,3,4,5,6) in the simulation section have shown a good performance and higher ability for e-rls than rls to track fast time variation of rayleigh fading channel since the e-rls blue line more close to the original channel red line than rls black line, as well table 2 explain erls superiority by comparing output value for each algorithms also the simulation program have been plotted in the figure (7). the future work for this paper, apply these algorithms to track other channels, i.e, finite impulse response complex (fir) channel or rician fading channels to see which algorithm has a good ability to track fast amplitude variation than other. 6. references [1] jayesh h. kotecha, petar m. djuric, "blind sequential detection for rayleigh fading channels using hybrid monte carlo-recursive identification algorithms", signal processing, 84(5):825-832, 2004. [2] j.h. lodge, m.l. moher, "maximum likelihood sequence estimation of cpm signals transmitted over rayleigh flat-fading channels", ieee trans. commun. 38 (6) (june 1990) 787–794. [3] g.m. vitetta, d.p. taylor, "multisampling receivers for uncoded and coded psk signal sequences transmitted over rayleigh frequency-flat fading channels", ieee trans. commun. 44 (2) (february 1996) 130–133. [4] h. zamiri-jafrian, s. pasupathy, "adaptive mlsd receiver with identification of flat fading channels", international conference on acoustics, speech and signal processing, 1997. [5] e. eleftheriou and d. d. falconer, "tracking properties and steady-state performance of rls adaptive filter algorithms", ieee trans. acoust., speech, signal processing, vol. assp-34, pp. 1097–1110, 1986. [6] a. benveniste, "design of adaptive algorithms for the tracking of time varying systems", int. j. adaptive contr. signal processing, vol. 1, pp.3–29, 1987. [7] e. eweda, "comparison of rls, lms, and sign algorithms for tracking randomly timevarying channels", ieee trans. signal processing, vol.42, pp. 2937–2944, 1994. [8] o. macchi, "optimization of adaptive identification for time-varying filters", ieee trans. automat. contr., vol. ac-31, pp. 283– 287, 1986. [9] ali h. sayed, "adaptive filter", a john wiley & sons,inc.,publicatio n, 2008. ��ح ���ي � � � 2016( 7378، ���� 1، ا���د�12� � ا���ارز� ا������� ا�( 78 ��� ' را$�ي �� ��ع �%$# e-rls و rlsا� ! ر�� ( / .-,# ا���+ ا�� *( ا� � ا�-�1% �# ا��0 ��ح ���ي� &���� %$�اد/ "�!� ا� ���� ا���ارز��/ ��� ھ���� ا�������ت وا� ��ت ali_info27@yahoo.com : ا��,+)و*� ا�()'� ا��.-� �'�/ <�م )e-rls(و) rls( ا���ار�!�ت>�7 (/; ')"8ا� اھ:، را'�� �����0 �)'5 ا�+$!) �5 ا�2�8 وا����7 ���ة++(5 ا03�4 ا��2 أ&0 �ا�+ ھ� أ"e -rls (3إ�7 ا�+�+�ج ��eده ھ:ا ا�(/; �0-و ��7 %��+��!2 ا�>�7'�اي � >2 ا���b ������ت �%+��!2 ا���b ا����a 2� 0!) ا�@+!�ج ا�7 ا' +(5 و ��!2 ا���b ا����0 >��!� د�2�rls 2� h,�+�' ���h &�وى �i 5'(� (!$+ا� )��ا ji>�7 و�5 ا�2�8 )���ة را'�i � %��@ � �%)*��kl�+�� k ا�+ ."�eءة ھ:ه ا���ارز�!�ت ��+q"� �2 ة�) ١٠٠ 0 إ�7 ) ا�+<(�ل/ إر��ل ("3) �2 �)ة وا@�ة �4/�"�ة �2 +(5 ا4داء و breast tumor diagnosis using diode laser in near infrared region al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 5, no. 2, pp 20 -31 (2009) breast tumor diagnosis using diode laser in near infrared region munqith s. dawood* and ahmed ali mohammed** * medical engineering departmen / college of engineering / al-nahrain university ** biomedical engineering department / al-khwarizmi college of engineering / baghdad university ahmed.ali1981@yahoo.com (received 11 july 2009; accepted 24 march 2009) abstract in the last years, new non-invasively laser methods were used to detect breast tumors for preand postmenopausal females. the methods based on using laser radiation are safer than the other daily used methods for breast tumor detection like x-ray mammography, ct-scanner, and nuclear medicine. one of these new methods is called fdpm (frequency domain photon migration). it is based on the modulation of laser beam by variable frequency sinusoidal waves. the modulated laser radiations illuminate the breast tissue and received from opposite side. in this paper the amplitude and the phase shift of the received signal were calculated according to the original signal for the sake of diagnosis. these calculations were carried out for different breast thicknesses to find out the best modulation laser beam wavelength and the optimum breast thickness necessary for diagnosis of benign and malignant tumors. according to our work the most suitable laser wave length to detect the breast tumor for preand postmenopausal females was 956 nm and 674 nm for both malignant and benign tumors. keywords: tumor detection, laser modulation, photon migration breast tumor 1. introduction different methods of breast diagnosis are used; some of these methods are painful like fine needle aspiration or surgical biopsy to examine the slices microscopically to diagnose the tumor (benign or malignant). in the last years a new method was found to detect the breast tumor non-invasively. this method is called frequency domain photon migration (fdpm) [1]. it is more specific than the other common methods used for breast tumor detection like x-ray mammography, ct scanner, ultrasound, mri and nuclear medicine. the fdpm is a safe method compared with the other methods because x-ray mammography and ct scanner has some risk of the exposure to their radiation and radioactivities. the mri is also expensive and cannot detect the micro classification of the breast tissue. the ultrasounds and the other methods cannot differentiate between the benign and the malignant tumor except the nuclear medicine. all these methods used fine needle aspiration or surgical biopsy to differentiate between the benign and malignant. this new method based on the use of a sinusoidally modulated intensity of diode laser within the nir (near infrared) region to penetrate deeply through the breast tissue which is described as a highly scattering media for light. a detector in the opposite side of the compressed breast (to reduce the thickness of the breast) is used to collect the laser beam after its penetration through the tissue. in this paper the fdpm method is discussed and is used to detected and identify the different breast tumors. theoretically, six laser wavelengths, modulated by different frequencies were used to choose the best one which gives the clearest results. mailto:ahmed.ali1981@yahoo.com munqith s. dawood al-khwarizmi engineering journal, vol. 5, no. 2, pp 20 -31 (2009) 2 2. the basic principle of frequency domain photon migration method optical methods applications in medicine are attractive because they are noninvasive, quantitative, and relatively inexpensive and pose no risk of ionizing radiation. the fdpm can successfully be used in vivo to detect the presence of small palpable breast lesions in women with previously diagnosed breast abnormalities [13]. recently a number of phase resolved optical spectrometers has been developed with the aim of obtaining the absorption coefficient μa and the reduced scattering coefficient μs `. consider that a sinusoidally modulated light source of the form: ( )( )tasinii += 10 passed through the sample of the tissue, where i is the instantaneous detected intensity, i0 is the peak intensity; a is the modulation depth and  is the angular modulation frequency. it is clear that a number of parameters can be measured, or calculated after passing the sample of tissue like the phase shift through the sample, and the attenuation of the optical signal as shown in figure (1). fig.1. time evolution of the intensity from a sinusoidally intensitymodulated source. the detected photon-density wave retains the same modulation frequency as the source photondensity wave but is delayed because of the phase velocity of the wave in the medium. the reduced amplitude of the detected wave arises from attenuation related to the scattering and the absorption processes. fdpm employs intensity-modulated nir light to characterize tissue quantitatively in terms of its optical parameters; i.e., the reduced-scattering coefficient (µs ’) and the absorption coefficient (µa). the concentration of significant nir absorbers like deoxyhemoglobin (hb), oxyhemoglobin (hbo2), water, and adipose can be calculated by using the measured µa values [2, 5]. multiple scattering of light in breast tissue occurs as a consequence of spatial variations in refractive index, which are influenced by cellular and extracellular matrix density [6]. both µa and µs ’ provide an understanding of changes in tissue cellularity, metabolic activity, physiology, and host response to cancer. detection of lesions is based on the functional contrast between normal and diseased tissue in the same patient. however, the physiology of healthy breast tissue is complex, influenced by multiple internal and external factors such as menstrual-cycle phase, menopausal status, exogenous hormones, lactation, and pregnancy. consequently, to establish a better basis for optical detection and diagnosis based on differential functional contrast, the optical properties of normal breast tissue must be carefully examined and characterized. this technique can be useful for the detection of the physiological status and changes in biological tissues. therefore, great effort has already been expended in developing noninvasive optical methods for early diagnosis of breast cancer. these methods are based on the detection of changes in optical characteristics, like the absorption and scattering coefficients, µa and µs ’ of the normal and malignant tissues. the optical methods have their problems arise from the fact that natural variations in the absorption and scattering in normal tissues of different patients exceed the changes in the parameters due to pathological modification of a tissue from an individual. this dictates the necessity for comparison of µa and µs ’ in the normal and pathologically modified tissues of individual patients. the beer–lambert law in its simple form is not valid for turbid media because photons pass through a scattering medium along trajectories of various lengths and forms [7]. in this paper the breast optical properties of healthy and tumor tissues were used in a fdpm mathematical model of breast tissue for different wavelengths (674, 782, 803, 849, 894, 956 nm) and different thicknesses of breast tissue ranging from 0.5 cm to 7.5 cm of premenopausal and postmenopausal females. a number of curves are drawn of the detected amplitude and phase shift of the simulated received laser intensity versus the frequency of the modulated ac signal that ranged up to 1ghz for each wavelength. munqith s. dawood al-khwarizmi engineering journal, vol. 5, no. 2, pp 20 -31 (2009) 3 3. laser interaction with biological tissue to study the tissue optical properties, we must understand the laser interaction with tissue, which is summarized in five forms as shown in figure (2): reflection, refraction, absorption, scattering and transmission. two other factors must be considered also, which are tissue factors and clinical factors. the tissue factors include the contents of tissue like the water, lipid, blood, organism, tissue thickness, tissue layers and types of tissues. while the clinical factors include laser power, laser beam, laser intensity and the stile of laser delivery (pulse or continuous) and the angle of beam incidence as well as the duration of exposure. fig.2. the types of laser energy interaction with tissue. 4. laser propagation in biological tissue these optical tissue properties essentially depend on the wavelength of the incident laser, the index of refraction, the attenuation and scattering coefficients µa and µs of the tissue. in the visible electromagnetic spectrum, the most important absorbers of biological tissue are melanin in the skin and hemoglobin in the blood; whereas in the near and mid infrared, water absorption becomes dominant. the scattering continuously decreases from uv towards the infrared [8]. human tissues contain a variety of substances whose absorption spectra at nir wavelengths is well defined, and which are present in sufficient quantities to contribute significant attenuation to the transmitted light. the concentration of some absorbers, such as water, melanin, and bilirubin, remains virtually constant with time. however, some absorbing compounds, such as oxygenated hemoglobin (hbo2), deoxyhaemoglobin (hb), and oxidized cytochrome oxidaze (ctox) have concentrations in tissue, which are strongly linked to tissue oxygenation and metabolism. increasingly dominant absorption by water at longer wavelengths limits spectroscopic studies to less than about 1000 nm. the lower limit on wavelength is dictated by the overwhelming absorption of hb below 650 nm. however, within the 650-1000 nm window, it is possible with sensitive instrumentation to detect laser, which has traversed up to 8 cm of tissue [9]. 5. breast tissue one of the major structural features of breast tissue is the large adipose fraction typically near the periphery of the breast, as shown in figure (3), which is thought to be an average of nearly 75% in women. however, a large variation exists among individuals, based on body mass index and breast size [10]. in the interior of the breast, there is often glandular tissue, which has higher blood content and hence higher water content. this area is thought to have a higher scattering power, perhaps owing to smaller scattering sites. although the origin of the scattering has not been established clearly in areas of adipose tissues where fat content is high, the scattering power is low, again perhaps because of the larger scattering centers of the lipid-filled cellular space. the scattering power is high in the interior of the breast and decreases toward the exterior [11]. the breast tissue is surrounded by a layer of skin that covers it from all directions that lead to extra scattering media for penetrating light. the breast is a gland designed to make milk. the lobules in the breast make the milk, which then drains through the ducts to the nipple as shown in figure (3). like all parts of the body, the cells in the breasts usually grow and then rest in cycles. the periods of growth and rest in each cell are controlled by genes in the cell's nucleus. the nucleus is like the control room of each cell. when the genes are in good working order, they keep cell growth under control. however, when the genes develop an abnormality, they sometimes lose their ability to control the cycle of cell growth and rest. munqith s. dawood al-khwarizmi engineering journal, vol. 5, no. 2, pp 20 -31 (2009) 4 fig. 3. the histology of the breast tissue where the breast profile is:1-breast profile: a=ducts, b=lobules, c=dilated section of duct to hold milk, d=nipple, e=fat, f=pectoralis major muscle, g=chest wall/ribcage, 2enlargement: a=normal duct cells, b=basement membrane, c=lumen (center of duct). 6. breast cancer cancer occurs when cells become abnormal and keep dividing and forming more cells without control or order. this creation of mass of extra tissue, called a growth or tumor, can be benign or malignant. the presence of these cancerous tumors within the healthy breast tissue will change its optical parameters. in this paper, we study the effect of these changes in optical parameter of breast tissue due to the presence of ductal carcinoma in situ (dcis), invasive ductal carcinoma (idc), invasive lobular carcinoma (ilc) and fibroadinoma. 7. frequency domain since any measurement in the time domain can be equivalently expressed in the frequency domain, techniques have also been developed which have sought to acquire transmitted light information in the frequency domain directly. the frequency domain techniques involve illuminating the object tissue with an intensity-modulation beam, and measuring its amplitude and phase shift after passing through the tissue. the transport of the modulated beam is often described in terms of the propagation of so-called photon density waves. most experimental work performed so far has utilized frequencies of a hundred mhz, which are equivalent to a temporal resolution of a few nanoseconds and photon density wavelengths of the order of a nanometer [8]. frequency domain techniques allow for the separation of the absorbing properties from the scattering properties of multiple-scattering media [12]. fig. 4. schematic diagram representing the application of fdpm method in breast cancer diagnosis. 8. frequency domain photon migration system an overall view of the frequency domain photon migration (fdpm) instrument is schematically depicted in figure (4). the fdpm instrument is constructed to measure phase and amplitude of photon density waves over a broad range of modulation frequencies and for different optical wavelengths. measurements of phase and amplitude over the range of modulation frequencies are performed in a sequential fashion for each wavelength. selection of a specific wavelength is achieved through coordinated switching of different rf to modulate different diode laser circuits. a dc current source provides constant biasing current to each diode. the basic circuit superimposes the rf signals with the dc currents; the combined currents are used to derive a given laser. thus, the diode will produce a sinusoidal modulated lasers. the dc bias and rf modulation currents are uniquely set for each munqith s. dawood al-khwarizmi engineering journal, vol. 5, no. 2, pp 20 -31 (2009) 5 diode laser by considering their maximum current ratings and rf impedance characteristics. presently, six diode lasers at 674, 782, 803, 849, 894 and 956 nm are used; however, additional diode lasers can be readily incorporated to extend the wavelength spectrum of the fdpm instrument. the optical switch couples intensity-modulated light to a selected output port. rf and optical switching are coordinated so that only one diode laser is modulated at a time. the phase data represent the phase difference between the sample and reference signal, while the amplitude data represent a ratio between the sample and reference signal amplitude of the normal tissue. 9. the theory light propagation in tissue can be modeled as transport of particles, which perform a random (walk) in the scattering medium due to multiple collisions. thus, the photon diffusion approach is an appropriate way of describing light propagation in a highly scattering media. the diffusion equation is a useful approximation of boltzmann transport equation. it describes well the light transportation in a multiple scattering media of thickness d [2, 5, and 12]: ( ) ( ) ( ) ( ) ( )dstddtddd a 0 2 ,, =+−  …(1) where d is the source detector distance, µa is the absorption coefficient, s0(d) is the photon source term and d(d) is the diffusion coefficient. the diffusion approximation can be used in the case of the mean free path for light absorption more than the mean free path for light scattering. in tissues, light scattering is primarily in the forward direction at a microscopic level, but on the length scale of the reduced scattering coefficient, the photon flux is isotropic. the photon flux, ø (d, t), (photons.cm-2.s-1) that moves along a photon density gradient, u (d, t), (photons.cm-3) is [2]: ( ) ( ) ( ) ( )tdudtdutd sa ,, 3 , ' −= + −=     …(2) where ν represents the photon frequency, and d represents the diffusion coefficient given by: ( )'3/1 sad  += …(3) where µs ` is the reduced scattering coefficient and it is represented by : ).1(' gss −= where g is the average of the cosine of the scattering angle. the source term is usually considered an isotropic emitter located at the origin in the frequency-domain. the intensity of the light source is modulated at a frequency (/2), and the photon density wave is: ( ) −−+= tiacdcu .exp  …(4) where ac represents the amplitude (alternate component), dc is the time-averaged intensity (direct component), and φ is the phase of the photon density wave. in the frequency-domain spectroscopy, considering a homogeneous medium, the source term is a spherical photon density wave: ( ) ( ) ( ) tiadstds .exp1..,0 −+= , where  (d) is the dirac function at the sourcedetector distance d, s is the source strength (in photons.s-1), and a is the modulation depth of the source. the absorption coefficient µa is the inverse mean distance a photon travels before it is absorbed. the absorption coefficient has units of reciprocal distance, and is typically 0.05–0.3 cm−1 for tissues in the wavelength region between 700 nm and 900 nm [13]. the reduced scattering coefficient µs ‘ is a measure of scattering per unit distance, and is typically 4 – 15 cm−1 for tissues. the reduced scattering coefficient refers to effectively isotropic scattering events and it is given by the inverse of the mean distance over which a photon loses the memory of its original direction of propagation. in tissues, the µs ’ is typically one order of magnitude bigger than µs. for an infinite, macroscopically uniform medium, the diffusion equation of a sinusoidal intensity-modulated point source for the photon density u(d, t) at a distance d relative to the source at time t to yield (in photons per unit volume) could be presented as follows [12]: munqith s. dawood al-khwarizmi engineering journal, vol. 5, no. 2, pp 20 -31 (2009) 6     −−                           +                                + − +               −= − − )(tan 2 1 sin .exp tan 2 1 cosexp 4 exp 4 ),( 1 4/1 22 222 1 4/1 22 222 2/1          ti d id d d dd sa d d dd s tdu a a a a a v v vv v vv …(5) the speed of each photon in the medium surrounding the scattering particles is given by v = (3.001010cm/s)/n, n being the index of refraction of the transporting medium, where μs ` is the reduced scattering coefficient, and µs is the scattering coefficient. s is the source strength (in photons per second), a is the modulation depth of the source, and ε is the phase of the source. in eq. (5), it is predicted that the photon density u(d, t) is generated by an isotropically emitting, sinusoidally intensity-modulated point source immersed in an infinite medium which constitutes a scalar field that propagates at a constant speed in a spherical wave and attenuates as a decaying exponential in d, divided by d, as it propagates. the photons injected into the medium are initially scattered at a distance of 1/ (µa+µs `) (i.e., one mean free path) from the end of the optical fiber source [14]. the assumption is that these first interactions are sufficiently localized that a simple diracdelta function accurately describes the light propagation when d>>1/µs. the source terms s, a, and ε are obviously independent of the quantities of interest, namely, the absorption and scattering coefficients [µa(λ),µs ’(λ)] of the medium at some light wavelength λ. ideally the source terms are also independent of ν, but in practice they are not. one possibility that eliminates these source terms from a measurement at a given v is to measure the properties of the photon density at two different source/detector separations, namely, d and d0, and compare the quantities obtained at these two distances. eq. (5) yields expressions for quantities obtained at d relative to the corresponding quantities obtained at d0, namely, the steady-state photon density dc, the amplitude of the photondensity oscillations ac, and the phase shift of the photon-density wave φ. the relative quantities are given by [15] ( ) ,exp )( )( 2/1 0 0 0               −−= = d dd d d ddc ddc dc a rel  …(6)                            + −−=  − a a rel d dd d d dac dac ac    v v v 1 4/1 22 222 0 0 0 tan 2 1 cos )(exp )( )( …(7) .tan 2 1 sin )( )()( 1 4/1 22 222 0 0                        + −= − −  a a rel d dd dd     v v v …(8) the relative demodulation of the photon-density wave is given by relrelrel dcacm / …(9) our frequency-domain data are obtained in a manner that allows for fitting these data (i.e., dcrel, acrel, φrel, and mrel) directly to eqs. (6)– (9) to obtain the absorption and the reduced scattering coefficients [µa(λ),µs `(λ)] of the multiplescattering medium at some light wavelength λ. note that in the three equations [eqs. (6)– (8)], there are only two unknowns, namely, vµa and vd, where d is given by eq. (3). we assume that the index of the refraction of the transporting medium is known, so that explicit values for µa (λ) and µs ` (λ) can be recovered from the quantities vµa and vd. this means that in principle only two out of the three expressions in eqs. (6) – (8) are needed to determine µa (λ) and µs ’ (λ) at a single modulation frequency /2, using different combinations of eqs. (6) – (8). munqith s. dawood al-khwarizmi engineering journal, vol. 5, no. 2, pp 20 -31 (2009) 7 10. results in our work on the theoretical simulation, the results of calculations are presented in thirty two figures to compare the effect of using six laser wavelengths (674, 782, 803, 849, 894, and 956 nm): sixteen figures for premenopausal female and sixteen for female. the figures show the calculated variations of the amplitude and phase shift of the received laser light based on fdpm method. the results in each figure are presented by four curves: one for normal breast tissue and three for different breast tumors (dcis, fibroadinoma and invasive carcinoma). the calculations were carried out for modulation frequencies ranged up to 1 ghz for different breast thicknesses. in this paper we present only four groups of the curves in figures 5 a, b, 6 a, b, 7 a, b, and 8 a, b. figures (5 and 6) are for premenopausal female and figure (7 and 8) are for postmenopausal female. the figures for amplitude and phase shift versus rf frequency modulation are shown for different tissue thickness, and different wavelength (λ = 674, 782, 803, 849, 894, and 956 nm); the aim is finding out the best wavelength to be used in cancer diagnosis and for different female ages. figures (5 and 7) are carried out and for 0.5 cm tissue thickness and figure (6 and 8) are carried out for 5.5 cm tissue thickness. 11. discussion preand postmenopausal normal breasts exhibit clear wavelength-dependent differences in both absorption and scattering parameters. the scattering is approximately 20% greater in premenopausal (μs ’ ~ 0.8 to 1.1 mm-1) group of women than in post-menopausal women (μs ’ ~ 0.67 to 0.86 mm-1). in addition, the wavelength dependence of scattering is steeper for premenopausal women. these findings are consistent with known changes in breast physiology. breast tissue, while under hormonal control, has higher glandular/cellular content and collagen is required in the extracellular matrix in order to support the structural demands of cellular proliferation. after menopause, the absence of hormonal stimulation results in glandular shrinkage, collagen remodeling to fat and diminished vasculature. since small tissue structures such as collagen fibers and subcellular organelles are likely to be the primary contributors to tissue scattering, it is not surprising that the wavelength dependence of scattering is relatively steep for premenopausal women. in contrast, following conversion to a principally large-particle fatty matrix, a much more gradual wavelength dependence of scattering is observed. thus, the diminished contribution of the glands and collagenous stroma leads to a clear wavelength-dependent scattering reduction. variations in absorption can be explained in a similar manner. these results demonstrate the intrinsic sensitivity of fdpm to breast tissue physiological states. in order to address the origin of photon migration signals in solid tumors, we have initiated breast tumor studies in human subjects. from the resulting curves in figures (5, 6, 7, and 8), there are two-fold advantages: 1) enhanced early detection of relatively small lesion even with long distance between the source and the detector (0.5 to 7.5 cm thickness, and 2) more specific characterization of benign versus malignant lesions would lead to reductions in the large but unnecessary surgical biopsies. the method fdpm is useful to differentiate between the types of tumors and the normal tissues. according to the figures used in multi thicknesses between 0.5 – 7.5 cm and multi frequency modulation from 0 – 1ghz, the curves clearly differentiate between the tumors and health tissue as shown in figures (5 – 8), for the wavelengths 674 nm and 956 nm, in the amplitude. because the tumors are close to each other and to the normal curve, the fibroadinoma and the invasive carcinoma are very clear to be differentiate but the invasive carcinoma in situ is not very clear differentiated because it is closed to the normal curve so it must be diagnosed by two wavelengths (674 and 956 nm). the best modulation frequencies that we can diagnose the tumors very clearly thoroughly rang between 800 mhz to 1 ghz. so to get the best result for beast tumor diagnoses, we suggest using two wave lengths 674 nm and 956 nm at both amplitude and phase shift and at frequency modulation between 800 mhz to 1ghz to avoid the mistake. for postmenopausal female, the recommended thicknesses are between 0.5 to 5.5 cm. average premenopausal μa values (0.0048– 0.015 mm-1) at each wavelength are 2.3-to 3-fold higher than postmenopausal absorption (average μa = 0.0016–0.0064 mm-1). furthermore, all postmenopausal μa values are less than 0.007 mm1. premenopausal women have 16 –22% higher munqith s. dawood al-khwarizmi engineering journal, vol. 5, no. 2, pp 20 -31 (2009) 8 b a b a scattering values at each wavelength (average μs `= 0.83-1.1 mm-1) than postmenopausal subjects (average μs ` = 0.67– 0.86 mm-1) [9]. fig.5. a) the amplitude (ac) of the detected laser signal vs. the modulation frequency, b) the phase shift φ of the detected signal vs. the frequency for laser wavelength (λ = 674, 782, 803, 849, 894, and 956 nm) at tissue thickness 0.5 cm for premenopausal female. fig. 6. a) the amplitude (ac) of the detected laser signal vs. the modulation frequency, b) the phase shift φ of the detected signal vs. the frequency for laser wavelength (λ = 674, 782, 803, 849, 894, and 956 nm) at tissue thickness 5.5 cm for pretmenopausal female. munqith s. dawood al-khwarizmi engineering journal, vol. 5, no. 2, pp 20 -31 (2009) 9 fig. 7. a) the amplitude (ac) of the detected laser signal vs. the modulation frequency, b) the phase shift φ of the detected signal vs. the frequency for laser wavelength (λ = 674, 782, 803, 849, 894, and 956 nm) at tissue thickness 0.5 cm for postmenopausal female. fig. 8. a) the amplitude (ac) of the detected laser signal vs. the modulation frequency, b) the phase shift φ of the detected signal vs. the frequency for laser wavelength (λ = 674, 782, 803, 849, 894, and 956 nm) at tissue thickness 5.5 cm for postmenopausal female. b a b a munqith s. dawood al-khwarizmi engineering journal, vol. 5, no. 2, pp 20 -31 (2009) 10 the coefficient of scattering changes versus wavelength for postand premnopausal are shown in figure 9. fig. 9. coefficient of scattering vs. wavelength for pre. and postmenopausal females. the gradual μs ` vs. λ slope shown in figure (9) for the postmenopausal subjects reflects large particle scattering consistent with a high percentage of fatty parenchyma found in this age group. in younger women, the relatively steep μs ` vs. λ slope is likely to be influenced by the presence of extracellular collagen in addition to cellular/epithelial factors physiological differences between tumor and normal tissue are further amplified by calculations of water and blood content. [3]. the tumor absorption is consistent in the order of 2to 3.5-fold greater than normal tissue, as shown in figure (10) because in the regions of tumor the blood supply vessels are accumulated more widely than in the normal tissue. fig.10. coefficient of absorption of normal and tumor breast tissues vs. wavelength. 12. conclusions from the previous result, the best wavelengths used in this method are 674 and 956 nm. the best results in this work appear very clear in the frequency modulation ranging from (800 mhz to 1000 mhz). at small thicknesses of breast tissue, approximately between 0.5 to 2.5 cm, the tumor is difficult to be differentiated clearly in the wavelength 956 nm due to the insufficient absorption and scattering. so the received spectral amplitude and phase shift are very clear at breast tissue thicknesses that exceed 2.5 cm at 956 nm for modulation frequencies ranging from 800 mhz to 1000 mhz. 13. references [1] payam heydari, pai chou, keun sik no,”high frequency, miniaturized fdpm integrated system-on-a-chip”,ntroi retreat poster list, 2004. [2] lelia adelina paunescu.” tissue blood flow and oxygen consumption measured with near-infrared frequency-domain spectroscopy”, ph.d. thesis graduate college, the university of illinois at urbanachampaign, 2001. [3] s. fantini, s. a. walker, m. a. franceschini, m. kaschke, p. m. schlag, and k. t. moesta, ‘‘assessment of the size, position, and optical properties of breast tumor in vivo by noninvasive optical methods,’’ appl. opt. 37, 1982–1989 (1998). [4] tromberg, b. j., coquoz, o., fishkin, j. b., pham, t., anderson, e. r., butler, j., cahn, m., gross, j. d., venugopalan, v. & pham, d.” non-invasive measurements of breast tissue optical properties using frequencydomain photon migration” hilos. trans. r. soc. london, b 352, 661–668. 1997. [5] ryan lanning, bruce tuomberg. “noninvasive characterization of breast cancer using near infrared optical spectroscopy”. the uci undergraduate research journal 2000, pp. 43-50. [6] tuan h. pham, olivier coquoz, joshua b. fishkin, eric anderson, and bruce j. tromberg. ”broad bandwidth frequency domain instrument for quantitative tissue optical spectroscopy”. review of scientific instruments, vol. 71, no. 6, june 2000. 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 674 782 803 849 894 956 wavelength (nm) c o e ff ic ie n t o f s c a tt e ri n g ( 1 /m m ) post pre. munqith s. dawood al-khwarizmi engineering journal, vol. 5, no. 2, pp 20 -31 (2009) 11 [7] vladimir liger, alexander zybin, mikhail bolshov, and kay niemax.”dual wavelength method for molecular difference absorption measurements in turbid media”. applied spectroscopy vol.56, no. 2, 2002, pp. 250256. [8] j. b. fishkin, e. gratton, m. j. vandeven, and w. w. mantulin, ‘‘diffusion of intensitymodulated near-infrared light in turbid media,’’ in time-resolved spectroscopy and imaging of tissues, b. chance and a. katzir, eds., proc. soc. photo-opt. instrum. eng. 1431, 122–135, 1991. [9] clare elwell and hebden jem.”near-infrared spectroscopy”. ucl, biomedical optical research laboratory, january 6, 1999. [10] grazia arpino1, valerie j bardou 2, gary m clark1 and richard m elledge. ”infiltrating lobular carcinoma of the breast: tumor characteristics and clinical outcome”. breast cancer research, vol 6, no 3, 2004. [11] breast net http://www.bci.org.au “ductal carcinoma in situ (dcis), “an information guide for patients. nsw breast cancer institute, 2004. [12] joshua b. fishkin, peter t. c. so, albert e. cerussi, sergio fantini,maria angela franceschini, and enrico gratton.” frequency-domain method for measuring spectral properties in multiple-scattering media: methemoglobin absorption spectrum in a tissue like phantom”. applied optics, vol. 34, no. 7, 1 march 1995. [13] d. levitz, l. thrane, m.h. frosz, p. e. andersen, c. b. andersen, j. valanciunaite, j. swartling, s. anderssonengels, and p. r. hansen. “determination of optical scattering properties in highlyscattering media in optical coherence tomography images”. opt. expr. 12, 249259 (2004). [14] d. m. hueber1, m a franceschini, h y ma, q zhang j r ballesteros, s fantini, d wallace, v ntziachristos and b chance.” non-invasive and quantitative near-infrared haemoglobin spectrometry in the piglet brain during hypoxic stress, using a frequency-domain multidistance instrument" phys. med. biol. 46 (2001) 41–62. www.iop.org/journals/pb. [15] patterson m. s., chance b, and wilson b. c., ‘‘time resolved reflectance and transmittance for the noninvasive measurement of tissue optical properties,’’ applied. optics. 28, 2331– 2336, (1989). 31 20، صفحة 2، العدد 5مجلة الخوارزمي الهندسية المجلد منقذ سليم داود (2009) 12 تشخيص اورام الثدي باستخدام ليزرالدايود *احمد علي محمد* و * منقذ سليم داود جامعة النهرين /كلية الهندسة /قسم الهندسة الطبية * د جامعة بغدا /كلية الهندسة الخوارزمي ** قسم الهندسة الطب الحياتي/ ahmed.ali1981@yahoo.com خالصةال طريقة حديثة لتشخخي اورا الثخدب ستسختخدا الريخبر وسخدول تخدخي لراحخي للنختع سخي وسأخد سخل اليخذه اسختندت خ الخيرةالَسَنوات ااستخدمت في ِِ في يومنت ا مستأمرِة ِق الائالطر سيل كثر أمتنتً ِمل و ي األق عرى إستأمتي إشأتِع الريبِر ائالطر ستسختخدا تاشخأتعي الثخدب تصخوير مثخي الثخدب ِ ور الكشخ طب نووب و االشأة النووية كمت في الهبة ال كمت في لهتب المفراه الحربوني االشأة السينيِة الليسيخخة مولخختتلر عرخخى تحخخويِر شخخأتِع الريخخبرِ قخخة خخ الطري سخختندت( بِ ملخختِي تخخرددس تتفوتوِنخخالإِ دب سخخي إ ج لخخرة ِق اللديخخدةِ ائخخإحخخده خخ الطرتخخدعى مِة نسيِج ة إشأ تدخي ةِ متغّيرات ستردد َنظَّ ِمل اللتنِب المأتكِه وتستر الثدب الريبِر الم لقد ت يته ارتفتع و تقد او تذخر المولة النتف ة مقترنة ستلمولة االصرية اللي التشخي ِمرخخت خخمكَية لقيت خخ الحسخختستِت ح خخمِ خخروربِ و اف خخيِ ليخخبِر اشخخأتِع ال يإلكِتشخختِ أف خخي طخخوِي مخخول ة لرثخخدبفخخخترِ م سخختت س لتشخخخيِ األوراِ لرثخخدب س فيه الحميدِة والخسيثةِ األورا الخسيثخخة لكرتخخت نخختنوميتر 674و نخختنوميتر 956َكخختَل سخخي وسأخخد سخخل اليخخذهنخختع لإل الثخخدبِ اوراإلكِتشخختِ ملئمخخةطخخوي مولخخِة الريخخبِر األكثخخر ال والحميدة mailto:ahmed.ali1981@yahoo.com 11-19 al-khwarizmi engineering journal,vol. 13, no. 1, p.p. 1 optimization the parameters taguchi method to improve the surface roughness technical institute of al email: (received 10 august https://doi.org/10.22153/kej.2017. abstract magnetic abrasive finishing (maf) process is one of non suitable for different materials and produces high quality level of surface finish machining pressure. a set of experimental tests three levels and six input parameters. experimental estimat for stainless steel type 316 plate work piece, cycle between teeth, current, cutting speed, working gap (doe) and response surface methodology (rsm).these input parameters to improve the surface layer for results showed that all six input parameters have an influence on the change results showed that the surface roughness of the improvement in the change of surface roughness keywords: maf process, minitab software, orthogonal array. 1. introduction in maf process, the working gap between the magnet pole (end face) and the work piece is filled of with magnetic abrasive particles can be used such as bonded or unbounded powder. in the present work, bonded are prepared from ferromagnetic particles and abrasive particles. magnetic abrasive finishing techniques used for hard material [1] that the ability of maf to remove microchips, help to produce micro-relief layer gives higher surface properties. maf process was universal, simplicity; improved the quality of surface roughness (ra) more than 50 %.maf effective process,gives good economic environment ferromagnetic particles' acting such as a multipoint cutting tool, and develops finishing force and pressure, leading to the influence of the magnetic field density in the working gap khwarizmi engineering journal,vol. 13, no. 1, p.p. 1119 (2017) parameters of magnetic abrasive process using method to improve the surface roughness shakir m. mousa technical institute of al-mussaib / al-furat al-awsat technical university email: shakir.aljabiri_89@yahoo.com august 2016; accepted 15 december 2016) https://doi.org/10.22153/kej.2017.12.001 magnetic abrasive finishing (maf) process is one of non-traditional or advanced finishing method suitable for different materials and produces high quality level of surface finish where it uses magnetic force as a machining pressure. a set of experimental tests was planned according to taguchi orthogonal array (oa) l27 ( experimental estimation and optimization of input parameters for maf process work piece, six input parameters including amplitude of tooth pole, and number of ng speed, working gap, and finishing time, were performed by design of experiment (doe) and response surface methodology (rsm).these six input parameters in this research were optimized for all o improve the surface layer for work piece by using signal-to-noise ratio technique. ave an influence on the change in surface roughness(∆ra). in addition, the of the work piece decreased from 1.130 to 0.370µm that means high level of surface roughness (0.760)µm. minitab software, parameters, signal-to-noise ratio, surface roughness in maf process, the working gap between the work piece is particles maps, as bonded or unbounded onded are prepared ferromagnetic particles and abrasive magnetic abrasive finishing maf because the ability of maf to remove microchips, help to relief layer gives higher surface maf process was universal, d the quality of surface maf effective economic environment. ferromagnetic particles' acting such as a finishing force and pressure, leading to the influence of the magnetic field density in the working gap. the specialty of maf process was control the flexibility of tool, ferromagnetic powder sealing by magnetic field, one can control the density and rigidity of the magnetic brush, help to change the topography of ma the working gap, [2-4]. maf relatively process of polishing begin in us in1930s, magnetic abrasive finishing maf are famous in russia. this process was developed and growth between 1980-2000. many advantages of (maf) process, it is more successful to produce different complex shapes and suitable for finishing flat surface as well as inner and outer cylindrical surfaces. geeng-wei changet have clarified the principle working of maf process and the finishing characteristics by using abrasive powder consist of a mechanical mixture of ferromagnetic particles and silicon carbide (sic) abrasive with lubricant as unbounded magnetic abrasive powder. t moriet al-khwarizmi engineering journal using traditional or advanced finishing methods which is uses magnetic force as a planned according to taguchi orthogonal array (oa) l27 (36) with and optimization of input parameters for maf process amplitude of tooth pole, and number of were performed by design of experiment optimized for all noise ratio technique. the obtained ∆ra). in addition, the µm that means high level of surface roughness, taguchi was capability to of tool, ferromagnetic , one can control magnetic brush, that the topography of magnetic flux in maf is a modern relatively process of polishing begin in us in1930s, magnetic abrasive finishing maf are this process was developed and many advantages of (maf) process, it is more successful to produce different complex shapes and suitable for finishing flat surface as well as inner and outer wei changet et al.[5] have clarified the principle working of maf rocess and the finishing characteristics by using abrasive powder consist of a mechanical mixture of ferromagnetic particles and silicon carbide (sic) abrasive with lubricant as unbounded moriet et al.[6] have pdf created with pdffactory trial version www.pdffactory.com https://doi.org/10.22153/kej.2017 mailto:shakir.aljabiri_89@yahoo.com https://doi.org/10.22153/kej.2017 http://www.pdffactory.com http://www.pdffactory.com shakir m. mousa al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 1119 (2017) 12 studied the characteristics of magnetic field, and explained the mechanism of maf process for stainless steel ferromagnetic material work piece, using abrasive powder that was sintered from an total of alumina particles and iron .taguchi design of experiments (doe) is utilized on(maf) process. dhirendra et al.[7] to find out significant parameters affecting on the surface finish quality created using a mechanically abrasive powder mixture of ferromagnetic iron particles and silicon carbide (sic) abrasives. experimental results have specified that out put parameters for a change in surface roughness (δra), working gap and voltage found to be the most important significant input parameters after that cutting speed and then grain mesh number. numerical simulation and modeling of surface roughness (ra)in the magnetic abrasive finishing maf process . raghuram, et al. [8] have suggest mathematical model for the output response surface roughness (ra) in polishing stainless steel work piece surface. the mathematical model found to agree fairly well with the experimental set up results. jaeseob et al. [9] experimental estimation and optimization of the input parameters of maf process utilized the nonferromagnetic material magnesium alloy az31b work piece were accomplished by a design of experiments (doe) and the response surface methodology (rsm).the result show that pressure and magnetic force density of magnetic table and cutting speed of electromagnetic inductor was important significant parameters on amelioration of surface roughness (ra) in the second-generation of maf process. depending on the results, the prediction models were improved by utilizing signal-to-noise ratio and response surface model and more than suitable for surface roughness after that. this work aims to study the optimization and influence of parameters on the quality of surface of maf for stainless steel 316 work piece, by using experimental method then finding the prediction models by using signal-to-noise ratio with the minitab 17 software. 2. design of experiments 2.1. selection of maf parameters and their levels in the current paper six parameters, (amplitude of tooth pole, and number of cycle between teeth, which are formed the shape of electromagnetic pole, current, cutting speed, working gap, and finishing time) with three levels for each parameter are used to study the influence of maf method on the quality of the surface layer. the selection parameters and their levels are listed in table (1). table 1 , input parameters for maf process input levels symbol level 1 level 2 level 3 amplitude of pole geometry (mm) (a) 4 8 12 number of cycles of pole geometry (b) 4 6 8 finishing time (min) (c) 5 10 15 cutting speed (rpm) (d) 175 350 525 current (amp) (e) 1 1.5 2 working gap (mm) (f) 1 2 3 2.2. selection orthogonal array (oa) for experiment the designs of experiment in this work based on the orthogonal array technique were reduce the number of experiments. to investigate the performance of most effective experiments, there are six input parameters with three levels have been choose, the values of parameters and their three levels according to orthogonal array (oa) l27 (36) (27 experiments) were illustrate in table ( 2), which leads to reduce the highrequired number of experiments to 27 effective experiments [10]. pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com shakir m. mousa al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 1119 (2017) 13 table 2 , orthogonal array(oa)l27 3. experimental procedure of finishing process at first step in this present work the induct (electromagnetic) has designed and manufactured in the workshop , maf machine using for finishing flat surfaces by modulating milling machine its view as shown in fig (1), the gap was filled with powder (the abrasive powder was (67%) iron oxide with (33%) industrial diamond powder) , bounded together by wetting the powder using sae 20w lubricant, addition of lubricant increases the adhesive force between the iron particles and the diamond abrasives as well as between iron particles themselves shown in fig 2, and the current was applied by (dc) power supply. the other design data of electromagnetic inductor are the following. the inductor was a steel rod wrapped around a coil of wires, magnetic force was generate on the working gap, between pole and work piece: the characteristics of the electromagnetic inductor are, the raw material of the iron core is made of the low carbon steel (c 15), the cross-section dimensions of the iron core is a= 18 mm, the length (height) of the iron core is l = 250 mm, the magnetic coil wire is made of the copper and f the diameter is ø=1 mm and the number of turns is ` n = 2500, the electromagnetic inductor as shown in fig (3). the material of work piece plate is a grade stainless steel type 316, which it is chemical composition and some mechanical properties are listed in tables (3),(4) respectively, with required size (100×35×2) mm. the conventional vertical milling machine is used to fixed the work piece on the bed table of the maf machine and the inductor fixed by the spindle of the maf machine, the working gap filled with dose of powder (6 cm3). fig. 1. photograp of magnetic abrasive machine supply. fig. 2. schematic of mechanical alloying. fig. 3. electromagnetic inductor. № a b c d e f № a b c d e f 1 1 1 1 1 1 1 15 2 2 3 1 3 1 2 1 1 1 1 2 2 16 2 3 1 2 1 2 3 1 1 1 1 3 3 17 2 3 1 2 2 3 4 1 2 2 2 1 1 18 2 3 1 2 3 1 5 1 2 2 2 2 2 19 3 1 3 2 1 3 6 1 2 2 2 3 3 20 3 1 3 2 2 1 7 1 3 3 3 1 1 21 3 1 3 2 3 2 8 1 3 3 3 2 2 22 3 2 1 3 1 3 9 1 3 3 3 3 3 23 3 2 1 3 2 1 10 2 1 2 3 1 2 24 3 2 1 3 3 2 11 2 1 2 3 2 3 25 3 3 2 1 1 3 12 2 1 2 3 3 1 26 3 3 2 1 2 1 13 2 2 3 1 1 2 27 3 3 2 1 3 2 14 2 2 3 1 2 3 pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com shakir m. mousa al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 1119 (2017) 14 table 3, chemical composition of stainless steel type 316 plate [11 ] composition ranges w% ser. no. type c si mn cr ni mo zn ti s fe sn mg 1 st 316 0.08 0.75 2.00 18.0 14.0 3.00 -0.03 -- table 4, some mechanical properties of stainless steel type 316 plate [11 ] mechanical properties st 316 plate sheet strip tensile strength mpa hardness rockwall b elongation % yield strength mpa 515 95 max 40 205 three observed value of surface roughness (ra) was measured, before and after finishing then finding the mean value. the change in (δra), is the difference between the arithmetic mean surface roughness ra of the work piece before and after maf experiments. the output data measured is the surface roughness ra surface roughness by tester (srt-6200) used to measure the values of ra at three different places at same line in the work piece. the last step adjusts the value of the six input parameters (amplitude of tooth pole, and number of cycle between teeth, current, cutting speed, working gap, and finishing time) according to taguchi orthogonal array (oa). 4. results and discussions 4.1. signal-to-noise ratio the criterion outputs, response δra, was dependent variable in regression mathematical models, while the predictor’s parameters were the number of cycles of pole geometry, cutting speed of magnetic pole , amplitude of pole geometry, finishing time, working gap and current. table (5) shows the result of output response, experiment and regression for stainless steel 316 ferromagnetic material. the result evaluate with help the anova and s/n ratio, this result mention the amelioration of the surface roughness (ra) after maf process. in this study, taguchi technique was use, and the (s/n) ratio was select according to the criterion (large is better) to maximize the response. the s/n ratio calculated by using the statistical software minitab-17 as follows in equation (1) s/n = −10log (�� ∑ ����) …(1) where n represent the number of measurement (input) and yi is the measured values (output). by using the same software program to analyses the effective experimental and finding the mathematical models (regression),as follows in equation (2) δra = -1.667 0.0184 a + 0.206 b + 0.0298 c + 0.00120 d + 2.774 e 0.845 f + 0.00008 a*a 0.00713 b*b 0.00036 c*c 0.000001 d*d 0.256 e*e 0.0095 f*f 0.0275 a*e + 0.0181 a*f 0.1105 b*e + 0.0367 b*f 0.0333 c*e + 0.0147 c*f 0.001876 d*e + 0.000794 d*f …(2) r-sq= 93.74% where r-sq=coefficient of determination pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com shakir m. mousa al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 1119 (2017) 15 table 5, input parameters distribution according to taguchi orthogonal array(oa ) with result of experiments and regression for ferromagnetic material stainless steel 316 4.1.1. analysis of surface roughness magnetic abrasive finishing method improved the quality of the surface; the result has been analyzed by using the signal-to-noise ratio method to obtain the optimal level for each process parameter that corresponded to the largest (s/n) ratio are given in table (6-a) the means value were shown in table (6-b) while table (7) shows the result for s/n of each parameters at three levels to improving surface roughness, using anova software. the selection optimum conditions from table (8) were (a1, b3, c2, d1, e2, and f1). amplitude of pole 4mm, number of cycle 8, cutting time 10 min, the cutting speed 175 rpm, the current 1.5 mm and the working gap 1mm. these optimal conditions produce the optimum surface roughness. the predicted value of (s/n) ratio from table (8), which computed by equation: ∆������. = η��� + (�� − η���) + (�� − η���) + (�� − η���)+ (�� − η���) + (�� − η���)+ (�� − η���) … (2) = -5η��� + (�� + �� + �� + �� + �� + ��) where η��� represent the signal-to noise of surface roughness response, ai, bj, ck and di are the signal/noise of each input parameter according to difference of optimum level for maf parameters ( a, b, c, d, e, and f). this value is compare to determine the highest s/n ratio that always yields the optimum quality with minimum variance around the target value. table 6, (a) response table for signal to noise ratios larger is better № a b c d e f ra ,µm before maf ra,µm after maf δra,µm experiment δra regression error 1 4 4 5 175 1 1 0.968 0.588 0.380 0.352476 0.0275238 2 4 4 5 175 1.5 2 0.989 0.623 0.366 0.454619 -0.0886190 3 4 4 5 175 2 3 1.019 0.548 0.471 0.409905 0.0610952 4 4 6 10 350 1 1 0.915 0.440 0.475 0.468952 0.0060476 5 4 6 10 350 1.5 2 1.173 0.619 0.554 0.498952 0.0550476 6 4 6 10 350 2 3 0.738 0.417 0.321 0.382095 -0.0610952 7 4 8 15 525 1 1 1.000 0.560 0.440 0.473571 -0.0335714 8 4 8 15 525 1.5 2 0.898 0.433 0.465 0.431429 0.0335714 9 4 8 15 525 2 2 1.036 0.904 0.132 0.132000 -0.0000000 10 8 4 10 525 1 2 0.970 0783 0.187 0.149611 0.0373889 11 8 4 10 525 1.5 3 0.834 0.638 0.196 0.189778 0.0062222 12 8 4 10 525 2 1 0.911 0.759 0.152 0.195611 -0.0436111 13 8 6 15 175 1 2 0.793 0.587 0.206 0.258111 -0.0521111 14 8 6 15 175 1.5 3 0.773 0.475 0.298 0.301778 -0.0037778 15 8 6 15 175 2 1 1.130 0.370 0.760 0.704111 0.0558889 16 8 8 5 350 1 2 0.900 0.571 0.329 0.314278 0.0147222 17 8 8 5 350 1.5 3 0.845 0532 0.313 0.315444 -0.0024444 18 8 8 5 350 2 1 0.702 0.236 0.466 0.478278 -0.0122778 19 12 4 15 350 1 3 0.788 0672 0.116 0.103722 0.0122778 20 12 4 15 350 1.5 1 0.673 0.421 0.252 0.249556 0.0024444 21 12 4 15 350 2 2 0.882 0.683 0.199 0.213722 -0.0147222 22 12 6 5 525 1 3 0.752 0.562 0.190 0.245889 -0.0558889 23 12 6 5 525 1.5 1 0.739 0.583 0.156 0.152222 0.0037778 24 12 6 5 525 2 2 0.722 0.599 0.126 0.073889 0.0521111 25 12 8 10 175 1 3 0.903 0.675 0.228 0.184389 0.0436111 26 12 8 10 175 1.5 1 0.804 0323 0.481 0.487222 -0.0062222 27 12 8 10 175 2 2 0.955 0.580 0.375 0.412389 -0.0373889 level a b c d e f 1 -8.501 -12.607 -10.956 -8.608 -11.769 -9.094 2 -10.898 -10.738 -10.474 -10.283 -9.971 -10.999 3 -13.442 -9.496 -11.411 -13.890 -11.101 -12.748 4 4.941 3.111 0.937 5.221 1.798 3.654 delta rank 2 4 6 1 5 3 pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com shakir m. mousa al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 1119 (2017) 16 table 6, (b) response table for means table 7, experimental result and s/n ratio table 8, the predicted result mean and s/n of the optimum condition for ∆ra from table 6,(a),(b) the influence of factors are determined by calculating the (delta), the difference between the highest and lowest value of level. it should be noted that the optimum condition (a1, b3, c2, d1, e2 and f1) is not be found among the 27 tests of experiment carried out, since the orthogonal array represents only 27 from all possibilities 36 = 729 tests). so that ∆ra is determined the optimum condition. in the case of improving the surface roughness, the most significant factor that has certain effect on ∆ra for maf process (d, a, f, b, e and c). the predicted values for ∆ra (mean and s/n ratio at the optimum condition (a1, b3, c2, d1, e2 and f1) the actual value of ∆ra (mean and s/n) of maf process improving by using optimum condition determine by analyzing the first response as shown in table (8) 4.1.2 in order to find the effect of process parameters on the responses, the results presented in table (9). table 9, analysis of variance for s/n ratios level a b c d e f 1 0.4004 0.2577 0.3108 0.3961 0.2834 0.3958 2 0.3230 0.3429 0.3299 0.3361 0.3423 0.3119 3 0.2359 0.3588 0.3187 0.2271 0.3336 0.2517 4 0.1646 0.1011 0.0191 0.1690 0.0569 0.1441 delta rank 2 4 6 1 5 3 no. enhanced ra (µm) (mean) s/n ratio no. enhanced ra (µm) (mean) s/n ratio 1 0.380 -10.6923 15 0.760 -3.4526 2 0.366 -11.1191 16 0.329 -12.3597 3 0.471 -8.3360 17 0.313 -12.9563 4 0.475 -8.2458 18 0.466 -8.4502 5 0.554 -6.6323 19 0.116 -31.0568 6 0.321 -12.6529 20 0.252 -15.7031 7 0.440 -9.0691 21 0.199 -19.0935 8 0.465 -8.4732 22 0.190 -19.8280 9 0.132 -27.1309 23 0.156 -23.3498 10 0.187 -20.0873 24 0.126 -28.4043 11 0.196 -19.3315 25 0.228 -17.0774 12 0.152 -23.8764 26 0.481 -8.1121 13 0.206 -18.5624 27 0.375 -10.8424 14 0.298 -13.5556 mean and s/n for ∆ra a b c d e f 1 3 2 1 2 1 mean = 0.624444 s/n ratio= -1.46925 source df seq ss adj ss adj ms f p a 1 0.12185 0.005697 0.005697 0.67 0.451 b 1 0.046006 0.024491 0.024491 2.87 0.151 c 1 0.001090 0.001715 0.001715 0.20 0.673 d 1 0.127883 0.000978 0.000978 0.11 0.749 e 1 0.001499 0.033248 0.033248 3.90 0.105 f 1 0.094866 0.066421 0.066421 7.79 0.038 pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com shakir m. mousa al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 1119 (2017) 17 according to analysis of variance in table (9), the cutting velocity and number of cycle of pole geometry have a significant effect on the enhancements of surface roughness. it is clear from the anova that the finishing time and the current in this condition have the least effect on the surface roughness. 4.1.3.effect of maf process on the surface roughness the s-to-n ratio response graph for ra shown in fig (4). it is clear that decrease the amplitude (a), cutting speed (d), and working gap (f) cause to improve the surface roughness. it is observed that the increase number of cycle (b) cause to improve the surface roughness. it has revealed that as finishing time(c) and the current (e) increases the surface roughness increase; further increasing the working gap (f) and current decreases the surface roughness. mainly, improving the surface roughness (∆ra) depends on the amplitude and cutting speed, the optimum ra was obtained at the optimum condition. 321 0.40 0.35 0.30 0.25 321 321 321 0.40 0.35 0.30 0.25 321 321 a m ea n of m ea ns b c d e f main effects plot for means data means 321 -10 -12 -14 321 321 321 -10 -12 -14 321 321 a m ea n o f s n r at io s b c d e f main effects plot for sn ratios data means signal-to-noise: larger is better fig. 4. signal-to-noise ratio response graph for surface roughness the validity of this method for finishing the ferromagnetic stainless steel 316 plate have been also proved by obtaining scanning microscopic views of work pieces before and after maf fig (5). these views show the texture generated by contacting the magnetic abrasive powder in specified operating conditions with the work piece surface and the apparently smoothness occurs due to the application of the magnetic abrasive to the application of the magnetic abrasive finishing process. the highly scratched surface before maf was smoothed and the direction of the obtained texture after maf was changed according to the direction and the rotation of electromagnetic pole. before after fig. 5. sem photos of stainless steel 316 before maf process sem photos of stainless steel 316 after maf process 5. conclusions the present optimization concluded that the change in the ra prediction and analysis during maf process, the following inferences have been derive based on the results and discussion: 1. the optimum parameters are found at the (amplitude of pole 4mm, number of cycle 8, finishing time 10 min, the cutting speed 175rpm, the current 1.5amp and the working pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com shakir m. mousa al-khwarizmi engineering journal, vol. 13, no. 2, p.p. 1119 (2017) 18 gap 1mm) that gives the highest value of the change in ra. 2. the most significant factor effected on the change of ra is (cutting speed (d), amplitude of pole (a), working gap ( f), number of cycle (b), current (e) and finishing time (c). 3. the change in ra has tendency to reduce with the increase the amplitude of pole, cutting speed and working gap. 4. the change in ra give better improvement in test no 15=0.76 µm 5. the developed mathematical statistical model (regression ) for change in ra can be a desired result employed for the optimal chosen of the maf process parameters to attain best change in ra stainless steel 316 work piece, because the error is very small between the experiment and regression results. 6. the scanning microscopic shows the reduction in scratches and craters on the surface layer of stainless steel 316 workpiece and the surface was more smoothly after maf process. 6. references [1] h. kumar,s. singh, and p. kumar, “magnetic abrasive finishinga review”, international journal of engineering research & technology (ijert), vol, issue 3, march 2013. [2] vk ,jain “ advanced machining processes”. allied publishers, delhi, 2002. [3] yamaguchi h, and sato t, “ polishing and magnetic fieldassisted finishing”, intelligent energy field manufacturing interdisciplinary process innovations, 2012. [4] yu. m. baron, “ technology of abrasive machining in a magnetic field”, mashinostroenie, leningrad 1975. [5] geeng-wei chang, biing-hwa, and yan, rong-tzong hsu, “study on cylindrical magnetic abrasive finishing using unbounded magnetic abrasives”, international journal of machine tools & manufacture, vol.42 (2002), pp. 575–583. [6] t. mori, k. hirota, and y. kawashima, “clarification of magnetic abrasive finishing mechanism”, journal of materials processing technology, vols.143-144 (2003), pp. 682– 686. [7] dhirendra k. singh, v.k. jain, and v. raghuram, “parametric study of magnetic abrasive finishing process”, journal of materials processing technology, vol.149 (2004), pp. 22–29. [8] m. g. v. s. raghuram, suhas s. joshi, “modeling of polishing mechanism in magnetic abrasive polishing”, the 12th international conference of international association for computer methods and advances in geomechanics (iacmag), 1-6 october, 2008, goa, india. [9] jae-seob kwak, chang-min shin, “parameter optimization and development of prediction model for second generation magnetic abrasive polishing of az31b plate”, proceedings of the international multi conference of engineers and computer scientists (imecs), vol.2(2011), hong kong. [10] y. m. baron, s. l. ko, and j. i. park, “characterization of the magnetic abrasive finishing method and its application to deburring”, key engineering materials vols.291-292 (2005), pp. 291-296. [11] joseph r. davis asm international, jan 1, 1994 – "stainless steels"technology & engineering 584 pages pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com )2017( 11-19 صفحة ،2العدد ،13المجلد الھندسیة الخوارزمي جلةم شاكر محمود موسى 19 طریقة تاكوشي لتحسین جودة خشونة السطح باستخدامالمدخالت االمثل لعملیة الحك الممغنط موسى شاكر محمود التقنیة األوسطجامعة الفرات /المعھد التقني المسیب الخالصة من السطحي وھذه الطریقة مناسبة للمواد المختلفة وتنیج مستوى عالٍ اإلنھاءالمتقدمة في أو ةتقلیدیالغیر قائتعتبر عملیة الحك الممغنط واحده من الطر ةفق مصفوفة تاكوشي وكانت بثالثعلى ومجموعة التجارب خطط لھا .السطحي وتستخدم القوة المغناطیسیة لتسلیط الضغط أثناء عملیة القطع اإلنھاء القطب شكل تتشكل والتي األسنان،خطوات وعدد األسنان، ارتفاع (من المدخالت اإلفادةیم ظالتقدیر التجریبي وتع ،مستویات وستة مدخالت مكن االستفادةی، السطح استجابة ومنھجیة ب التجار تصمیم البحث باستخدام اتم تنفیذ )وقت التشغیلو العمل فجوةو القطع سرعةو التیارو الكھرومغناطیسي ٣١٦الفوالذ المقاوم للصدأ نوع لمشغولة التي تعطي أفضل سطح لتحسین الطبقة السطحیة الستة من ھذا البحث ھو لتحدید القیم المثلى لجمیع المدخالت المحصلة النھائیة ان ذلك فضال عن. وتشیر النتائج بأن جمیع المدخالت لھا تأثیر في تغیر الخشونة السطحیة. نسبة اإلشارة إلى الضوضاء بأستخدام تقنیة ة السطحیة الخشونالتغیر في في عالٍ تحسن على یدل مما مایكرومیتر) ٠.٣٧٠ ١,١٣٠( من انخفضت السطحیة الخشونة في التغیر أوضحت الى أن . مایكرومیتر) ٠و٧٦٠(. مقداره pdf created with pdffactory trial version www.pdffactory.com http://www.pdffactory.com http://www.pdffactory.com <4d6963726f736f667420576f7264202d20e3d5d8ddec20e6d5ddc7c120e6e3d1e6c935302d203539> al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 15, no. 2, june , (2019) p.p. 5059 investigation the influence of spif parameters on residual stresses for angular surfaces based on iso-planar tool path mustafa mohammed abdulrazaq * safaa kadhum gazi** marwa qasim ibraheem*** *,** department of production engineering and metallurgy / university of technology *email: mustafaalneame@yahoo.com **email: safaa_kadhim1988@yahoo.com ***email: techmarwa888@yahoo.com (received 5 june 2018; accepted 18 september 2018) https://doi.org/10.22153/kej.2019.09.002 abstract incremental sheet metal forming (ismf) is a modern sheet metal forming technology which offers the possibility of manufacturing 3d complex parts of thin sheet metals using the cnc milling machine. the surface quality is a very important aspect in any manufacturing process. therefore, this study focuses on the resultant residual stresses by forming parameters, namely; (tool shape, step over, feed rate, and slope angle) using taguchi method for the products formed by single point incremental forming process (spif). for evaluating the surface quality, practical experiments to produce pyramid like shape have been implemented on aluminum sheets (aa1050) for thickness (0.9) mm. three types of tool shape used in this work, the spherical tool gave higher residual stresses than other types, also three levels for each of step over and feed rates utilized. it found that residual stresses was raised up with increasing the step over and feed rate values, the effect of these variables studied on two slope angles. by using analysis of variance method (anova) found that the most influential parameter is step over with (59.18%) and (65.42%) for both slop angles; (α=45°) and (α=55°) respectively. keywords: incremental sheet metal forming, residual stresses, taguchi, single point incremental forming. 1. introduction incremental sheets metal forming is a high flexible forming process, which can forming the sheets through the motion of non-traditional tool to manufacture the complicated products shapes, and the equipments of forming is appropriate for a wide variant products without expensive investments or matched tools through the movement of the tools onto certain tool path [1, 2]. the small plastic deformation zone that occur in the incremental sheet forming mechanism produced higher strains compared to conventional forming operations and it required low forces to implement the forming process [3]. so a different and complex 3d shapes can be produced through the tool movement along accurate designed paths, so there are no needs for manufacturing special tool [3]. single point incremental forming (spif) is a comparative sheets forming technique that allow forming of complex shape without a specific die using single point tools 3-axis cnc milling machine [4]. the technology of (spif) uses layer manufacturing concepts. it implements the part geometry details in to a group of parameters by 2d layers, and later the local plastic deformations are occurred layer-by-layer using the motion of computer numerical control of a simple forming tools to manufacture products which have complicated shapes as shown in figure (1) [5, 6]. mustafa mohammed abdulrazaq al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 5059 (2019) 51 fig. 1. schematic representation of the spif process in 2013 radu crinaa, et al. [7]: investigated the residual stresses distribution through parts produced by single point incremental forming (spif) made by aa1050 pure aluminum. operation variables were variants to find out their effect on residual stress values and distributions: diameter of tool (d), tool vertical step (δz), and spindle speed (ω). he found that increasing the tool diameter decreasing the residual stresses, contrariwise with using large values of spindle speed and vertical step which gave high amounts of residual stresses. bogdan chirita, et al. (2014) [8]: studied the distribution of residual stresses through the part formed by (spif) operation as a work parameters function and to find out its influence on part quality using the same parameters above, it was found a favorable residual stress state and implying a suitable quality of the samples could be given using low diameter of the tool and step size as well, with higher values of spindle speed. this study focuses on the resultant residual stresses by forming variables, namely; (tool shape, step over, feed rates, and slope angle) using taguchi method for the samples formed by (spif) single point incremental forming method. g. vigneshwaran et al. (2015) [9], implemented an optimization task by discovering the influence of operation variables such as tool diameter, step size, spindle speeds and feed rates on the wall angle. aluminum sheets (al 6063‐ o) with 1 mm thickness has been used as a sheet metal. an l9 (34) taguchi orthogonal array has been used for designing the experiments and analyzing the result. using the (anova) technique, the results have been examined and it showed that the tool diameter, step size, spindle speeds and feed rates contribute (4%, 57%, 10% and 29%) respectively, provide a higher wall angle of (55°). 2. residual stress residual stress is an unavoidable concomitant with every manufacturing processes and fabrication operations and could also grows through the service, it can occurs with any sets of circumstances that lead to differential expansions or contractions among the adjacent pieces on a body in which the local yield strength is exceeded. there are two types of residual stresses tensile and compressive that depend on locations and the non-uniform volumetric type that occurs due to localizing the stress through the forming process as in shot peening, contoure rolling, etc. [10]. the determining of precise for residual stress is difficult using analytical methods. usually the value of residual stress is determined through experimental process. most of these processes are destructive. so the (xrd) x-rays diffraction method is the main non-destructive techniques in residual stresses measurements. [11]. x-ray emitted through a particular x-rays tube concentrated to a fixed pattern on the spectrometer axes (goniometer). diffracting xrays on samples in an overall angle of diffractions equal to (2θ). through a detector device the diffracting x-ray is computed. figure (2) clarify the principles of the process for the (xrd) method. fig. 2. principles of (xrd) process. assessment of residual stresses by x-rays diffraction depends on calculating the changes of inter-planar spacing of crystal lattice. mustafa mohammed abdulrazaq al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 5059 (2019) 52 3. taguchi experimental design method this technique depends on two groups; the first one is a special type of matrix called "orthogonal array (oa)" includes number of tests based on the number of levels for the controlling parameters, and the second one is (s/n) the signals to noise ratio. the expression ‘signal’ indicating to the required values (mean) of the outputs characteristics, beside that the expression (noise) indicating to the unrequired values. the calculation of (s/n) ratios is varying depending on objectives functions, i.e., a characteristics amount. [12]. designing the method using minitab16 program as follow: 4. variance analysis the experimental work results could be investigated by (anova) variance analysis to discover the effecting of forming variables on residual stresses through the entire process. in the analysis, the ratio between mean square errors and residual called fratio and it utilized for determining the importance of a parameter. f ratio correspondent to 95% reliable levels in calculations of the operation variables. p values are the report of importance levels of each parametr (appropriate and inappropriate) [13]. 5. machines and tools the experimental equipment includes: cnc milling machine, forming frame, sheet metal and the tools for forming. the incremental sheet metal forming is normally implemented on cnc milling machine, where it’s capable for assigning and controlling the movement of the forming tool through a certain 3d path. the experimental work has been implemented on 3-axes cnc machine (c-tek) model (km80d), that locates in university of technology/ workshops and training center for carried out forming process on the samples. the specifications of milling machine clarified in table (1) table 1, the cnc milling machine specification the hollow cylindrical frame is manufactured from medium carbon steel by metric turning machine with outer diameter (200 mm) and inner diameter (170 mm) and height of (200mm). a ring with radii equals to the radii of the forming frame has been used as a blank holder. as shown in figure (3) a piece of wood is utilized as a backing plate between the sheet metal blank and the forming frame in order to support the blank while forming and to compensate the lack of shape matching between the square top-view of the truncated pyramid product and the circular opening of both the forming frame and the blank holder. the backing plate is illustrated in figure (3) fig. 3. forming framework, (a) schematic illustration, (b) physical blank holder and forming frame. aspect specification units type (km-80d) travel (x, y, z) 1500 x 600 x 400 mm max. spindle speed 8000 rpm number of axis three cnc controller cnt series other specifications off line program. movable head mustafa mohammed abdulrazaq al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 5059 (2019) 53 three types of tool shapes have been utilized in this work: (spherical, hemispherical and toroidal heads) of 12 mm diameter for each one illustrated in figure (4). the lengths of all these types are (110 mm) manufactured from tool steel materials din-1530 with hardness of (60 hrc). fig. 4. the three types of forming tools. the sheet metal material which is used in this work is aluminum aa1050 alloy. table (2) clarifies the chemical compositions of the sheet metal. table 2, chemical compositions of aluminum sheets (aa 1050). elements al si fe cu exp. 99.3 0.096 0.33 0.035 mn mg ti v zn 0.026 0.025 0.013 0.018 0.042 the original dimensions of the sheets are (250×250×0.9) mm, and the work area diameter is 170 mm according to the inner size of the blank holder as shown in figure (5). fig. 5. size of aluminum blank used. the cad model of the products created by using siemens (ugs-nx9) program, for applying the incremental sheet metal operation on a pyramid like shape with depth (40) mm. two different angles for the inclined walls (45o and 55o), each two facing walls are equal as shown in figure (6). this geometry is kept constant for all the nine samples. fig. 6. dimensions details for the cad model of the product. in incremental forming, the tool motion is controlled numerically. consequently, a tool path of (z-level) type with constant vertical step called "iso-planar" tool path is generated for all products. the tool path starts from the outside of the shape towards the inner sides and incrementally goes down in the z-direction by a constant (∆z) value as shown in figure (7). nc codes are obtained from the generated tool path and transferred to the cnc machine. fig. 7. iso-planar tool path generation using ugsnx5 software. 6. design of experiments the designing of experimental tests has a great influence on the required experimental tests mustafa mohammed abdulrazaq al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 5059 (2019) 54 numbers. accordingly, the experiments of (ismf) required an appropriate design. the overall number of experimental tests is (9) experiments, on the basis of (3) levels and (3) variables (33) for partial design, the parameters levels are listed in table (3). the constant variables are: • tool path: iso-planer • spindle speed: 1000 r.p.m • lubricant: paraffin based gear oil sae 140 table 3, (ismf) parameters and levels. 7. implementation ismf process the experimental work for implementing the nine experiments that selected by designing of taguchi have been carried out on 3-axis cnc milling machine, fig (8) clarify the nine specimens produced by (ismf) process using the concern forming parameters on linear interpolation. this process is followed by measurement process using xrd method to clarify the effect of the parameters on the process. fig. 8. specimens after ismf process. 8. result and discussion the resultant residual stresses for the samples have been measured using x-ray diffractometer of type "shimadzu xrd-6000". this part demonstrates and discusses the results values of the tensional residual stresses depending on (3) forming variables; tool shape, feed rates and stepover, and using analysis of variance (anova) technique. the results will be performed to determine the contribution percentage of these parameters in the process, and obtaining the optimum values by using minitab program, when the experiments of the nine samples have been implemented. table (4) clarifies these variables and the resultant residual stresses over the parts regions. table 4, experimental work readings with residual stresses 8.1 the influence of forming parameters on residual stress figures (10) and (11) clarify the influence of tool shape, stepover and feed rate on the residual stresses for (α= 45°), while the figures (12) and (13) show the effect of these parameters on the residual stresses for (α= 55°). from these figures, it is obviously noted that the raise in step over leading to raise the amount of residual stresses, because of the high energy generated through the pressure that obtained higher stretch. also, increasing the feed rates leads to raise the residual stresses values because of increasing the friction at the interface between the tool and sheet leads to poor quality for the parts of. on the other hand, using spherical tool shape gives higher residual stresses than utilizing hemi-spherical or flat-end tool shape. level 3 level 2 level 1 parameter no. spherical toroidal hemispherical tool shape 1 0.7 0.5 0.3 step over (mm) 2 1200 1000 800 feed rate (mm/min) 3 no. tool shape step over (mm) feed rate (mm/ min) residual stresses (mpa) α = 45o α =55o 1 flat-end 0.3 800 11.327 15.786 2 flat-end 0.5 1000 25.353 27.845 3 flat-end 0.7 1200 33.258 53.789 4 hemispherical 0.3 1000 27.902 21.634 5 hemispherical 0.5 1200 35.770 36.990 6 hemispherical 0.7 800 37.927 57.049 7 spherical 0.3 1200 26.180 45.779 8 spherical 0.5 800 33.767 47.837 9 spherical 0.7 1000 45.925 62.528 3 2 1 4 5 6 9 7 8 mustafa mohammed abdulrazaq al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 5059 (2019) 55 fig. 10. xsurface plot of residual stresses vs. tool shape and step size for (α= 45°). fig. 11. xsurface plot of residual stresses vs. step size and feed rate for (α= 45°). fig. 12. xsurface plot of residual stresses vs. tool shape and step size for (α= 55°). fig. 13. xsurface plot of residual stresses vs. step size and feed rate for (α= 55°). 8.2 analysis of variance the aim of the analysis of variance (anova) in this work is for determining the significant operation variables and for measuring their influences on the residual stress. table (5) and (6) show the result of anova of factors influencing on the residual stresses. table 5, anova results for residual stresses (α=45°). source of variance dof sum of squares variance f ratio p(%) tool shape 2 256.9 128. 5 45.09 33.90 step over (mm) 2 448.4 224.2 78.67 59.18 feed rate (mm/min) 2 47 23.5 8.25 6.24 error, e 2 5.7 2.85 0.68 total 8 758 100 mustafa mohammed abdulrazaq al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 5059 (2019) 56 table 6, anova results for residual stresses (α=55°). source of variance dof sum of squares variance f ratio p(%) tool shape 2 602 301 15.05 27.96 step over (mm) 2 1409 704.5 35.23 65.42 feed rate (mm/min) 2 103 51.5 2.58 4.80 error ,e 2 40 20 0.68 total 8 2154 100 the f ratio of 78.67 for the step over is greater among the variables (see table 5). accordingly, the mostly effected variable at (α = 45°) is stepover (59.18%) which is about twice of tool shape (33.90%). the feed rate has a less influence with (6.24%). on the other hand, the most influential parameter at (α=55°) is also the step over with f ratio value (35.23), and the percentage of contribution is equal to (65.42%), superior to the first slope angle and it reached to three times of tool shape (27.96%) and several times of feed rate, which has the smallest effect on the process with (4.80%). through analyzing, fratio is the mean square error ratio to residual, and it is conventionally utilized to compute the importance of factors 8.3 optimal design conditions for residual stresses the optimum design conditions have been determined using the main effect plots to obtain the low values of residual stresses. increasing these kinds of residual stresses (tensile type) raises the availability of cracks and the possibility of failure through. and hence, the better forming parameters were selected using the spss software. figures (14) and (15) show the main effects plot for residual stresses with the process inputs. this plot shows the individual variation response of the three variables, i.e. stepover, tool shape and feed rates separately. the results showed that optimum conditions to the best residual stresses are: tool shape at level1(flat-end), step over on level 1(0.3 mm), and feed rate on level1(800 mm/min). fig. 14. mean effects plot for residual stress at (α = 45°). mustafa mohammed abdulrazaq al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 5059 (2019) 57 fig. 15. mean effects plot for residual stress at (α = 55°). 9. conclusions to summarize the concluded influences that deduced from these experiments, they could be sum up in: • the experimental results showed the main effects of process parameters on the residual stresses for al-alloy. the residual stresses increased with the increasing in step over and feed rates for both slope angles. • using spherical tool gives higher residual stresses than utilizing hemi-spherical or toroidal types. • the optimal conditions for best residual stresses were tool shape at level-1 (flat-end), step over at level-1(0.3 mm), and feed rate at level-1(800 mm/min). • from analysis of variance, the most influential parameter is the step over of (59.18%) and (65.42%) for both slop angles (α=45°) and (α=55°), respectively which is greater than tool shape and feed rate. list of abbreviations no. symbol meaning 1 ismf incremental sheet metal forming 2 spif single point incremental forming 3 cnc computer numerical control 4 xrd x-ray diffraction 5 oa orthogonal array 6 s/n signal to noise ratio 7 ∆z step over 8 p(%) percentage of contribution 10. references [1] p. lehtinen, t. väisänen & m. salmi "the effect of local heating by laser irradiation for aluminum, deep drawing steel and copper sheets in incremental sheet forming" physics procedia. vol. 78, pp. 312-319,2015. [2] k. jackson & j. allwood "the mechanics of incremental sheet forming" journal of materials processing technology. vol. 209, pp. 11581174,2009. [3] m. azaouzi & n. lebaal "tool path optimization for single point incremental sheet forming using response surface method" simulation modeling practice and theory, pp. (49–58),2012. [4] m. skjoedt, n. bay, b. endelt & g. ingarao "multi stage strategies for single point incremental forming of a cup" international journal of material forming. suppl. 1, pp. 1199 –1202,2008. [5] zemin fu, jianhua mo, fei han & pan gong " tool path correction algorithm for single-point incremental forming of sheet metal" mustafa mohammed abdulrazaq al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 5059 (2019) 58 international journal of advanced manufacturing technology. vol. 64, pp. 1239– 1248, 2013. [6] s. h. wu1, ana reis, f.m. andrade pires, abel d. santos & a. barata da rocha " study of tool trajectory in incremental forming" advanced materials research. vol. 472-475, pp. 15861591, 2012. [7] radu crina, herghelegiu eugen, tampu catalin and cristea ion "the residual stress state generated by single point incremental forming of aluminum metal sheets", journal of applied mechanics and materials vol.371, pp.148-152, 2013. [8] crina radu, catalin tampu, ion cristea, and bogdan chirita "the effect of residual stresses on the accuracy of parts processed by spif", journal of materials and manufacturing processes, vol. 28, pp. 572–576,2014. [9] g. vigneshwaran, v.s.s. kumar & s.p. shanmuganatan "optimization of process parameters in single point incremental forming of aa 6063‐o alloy" international journal of current engineering and scientific research. vol. 2, pp. 8-14, 2015. [10] h. vemanaboina, d.a. kumar, b.d. kumar, k.s. & l.s. nayak "residual stress measurement using x-ray diffraction for weldments" ijsrd || national conference on recent trends & innovations in mechanical engineering, pp 176-179, 2016. [11] a. zolanvari, s. h. sagha, f. eshaghi, z. shahedi & a. zendehnam "microstructure and residual stress measurement of ag/glass thin films using in-situ high-temperature x-ray diffraction" armenian journal of physics. vol. 9, pp. 15-19, 2016. [12] shukry h. aghdeab and laith a. mohammed, “studying parameters of edm based microcutting holes using anova”, eng. &tech. journal, vol.31, part (a), no.15, 2013. [13] wissam. k. hamdan “feasibility development of incremental sheet metal forming process based on cnc milling machine”, phd. thesis, university of technology 2009. )2019( 5059، صفحة 2د، العد15دجلة الخوارزمي الهندسية المجلممصطفى محمد عبد الرزاق 59 لألسطح الزاوية دراسة تأثير متغيرات عملية التشكيل احادية التماس على االجهادات المتبقية باالعتماد على مسار العدة االيزو بالنار ***قاسم ابراهيم ىمرو **صفاء كاظم غازي *مصطفى محمد عبد الرزاق الجامعة التكنولوجية / هندسة االنتاج والمعادن قسم*،** mustafaalneame@yahoo.com :البريد االلكتروني* safaa_kadhim1988@yahoo.com :البريد االلكتروني** techmarwa888@yahoo.com :البريد االلكتروني*** خالصةال ) هي عملية حديثة في تقنيات تشكيل المعادن، حيث توفر امكانية تصنيع االجزاء ثالثية االبعاد المعقدة للصفائح ismfعملية التشكيل التزايدية للصفائح ( . جودة السطوح المنتجة هو جانب مهم جداً في عمليات التصنيع، لذا فأن هذه الدراسة تركز على حصيلة cncالرقيقة بأستخدام مكائن التفريز المبرمجة ية من متغيرات عمليات التشكيل وهي (شكل العدد، مسافة االنتقال، معدل التغذية ودرجة ميالن السطح) والتي تم تحديدها بأستخدام طريقة االجهادات المتبق على اشكال تشبه نفذت التجارب العملية لعملية التشكيل ،تاكوشي لألجزاء المنتجبة بواسطة عملية التشكيل التزايدية احادية التماس. وذلك لتقييم جودة السطوح ملم. ثالث اشكال من العدد تم استخدامها في البحث، حيث ان العدة الدائرية اعطت )٠٫٩بسمك ( aa1050الشكل الهرمي لصفائح من سبيكة المنيوم نوع م استخدامها، و وجد ان قيم االجهادات اعلى قيم لألجهادات المتبقية عن باقي اشكال العدد. كذلك ثالثة مستويات من قيم مسافة االنتقال ومعدالت التغذية ت ريقة تحليل العناصر المتبقية ارتفعت بزيادة قيم مسافة االنتقال ومعدالت التغذية. ان تأثير هذه المتغيرات تم دراسته على درجتي ميالن للسطح. بأستخدام ط )anova ) لكال درجات ميالن االسطح ) %٦٥٫٤٢و( )%٥٩٫١٨) وجد ان اكثر متغير تأثيراً هي مسافة االنتقال بـ(α=45°) و(α=55°) على التوالي. abstract 82 al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 4, no. 4, pp 82-90 (2008) peak to average power ratio reduction of ofdm signals using clipping and iterative processing methods ahmed k. hassan electromechanical engineering department/ university of technology (received 5 march 2008; accepted 10 september 2008) abstract one of the serious problems in any wireless communication system using multi carrier modulation technique like orthogonal frequency division multiplexing (ofdm) is its peak to average power ratio (papr).it limits the transmission power due to the limitation of dynamic range of analog to digital converter and digital to analog converter (adc/dac) and power amplifiers at the transmitter, which in turn sets the limit over maximum achievable rate. this issue is especially important for mobile terminals to sustain longer battery life time. therefore reducing papr can be regarded as an important issue to realize efficient and affordable mobile communication services. this paper presents an efficient papr reduction method for ofdm signal. this method is based on clipping and iterative processing. iterative processing is performed to limit papr in time domain but the subtraction process of the peak that over papr threshold with the original signal is done in frequency domain, not in time like usual clipping technique. the results of this method is capable of reducing the papr significantly with minimum bit error rate (ber) degradation. keywords: ofdm, papr reduction, clipping method, iterative processing method. 1. introduction: multi-carrier transmission, also known as orthogonal frequency division multiplexing (ofdm) or discrete multi-tone (dmt), is a technique with a long history that has recently seen rising popularity in wireless and wire line application. the recent interest in this technique is mainly due to the recent advantage in digital signal processing technology and semiconductor technology. international standards making use of ofdm for high speed wireless communications are already established or being established by ieee802.11, ieee802.16, ieee802.20 and european telecommunications standards institute (etsi) broadcast radio access network (bran) committees [1]. for wireless application, an ofdm based system can be of interest because it provides greater immunity to multi-path fading and impulse noise eliminates the need of equalizers, while efficient hardware implementation can be realized using fast fourier transform (fft) techniques. unfortunately, one particular major problem with multi carrier signals that is often cited as the major drawback of multi carrier transmission is its large envelope fluctuation, which is quantified by the parameter called peak to average power ratio (papr). since most practical transmission systems are peak power limited, designing the system to operate in perfectly linear region often implies operating at power levels well below the maximum power available [2]. in practice, to avoid operating the amplifier with extremely large back offs occasional saturation of the amplifiers or clipping in digital to analog converters (dac) must be allowed. this additional process is a non linear process which creates intermodulation distortion that increases the bit error rate(ber) in standard linear receiver, and also causes spectral widening of the transmit signal that increase adjacent channel interference to the other users [3]. ahmed k. hassan al-khwarizmi engineering journal, vol.4, no.4, pp 82-90 (2008) 83 in this paper an efficient papr reduction method for ofdm signals is presented. this method is based on clipping; clipping is introduced to limit the peak power. however, this clipping process does not introduce spectral broadening, as exist in conventional clipping process, because the subtraction to the original signal is processed in frequency domain instead of in time domain and only affects minimum bit error rate (ber) performance degradation. the clipping process is also done iteratively because zero padding operation in frequency domain causes peak growth after converting to the time domain. the iterative processing method gives good results for papr reduction and suitable ber performance degradation. 2. ofdm system: orthogonal frequency division multiplexing (ofdm) system may be viewed as a conventional frequency division multiplexing (fdm) system, as shown in fig.(1-a). in this arrangement, the spectra of different subchannels do not overlap. in such a system, there is a sufficient guard space between adjacent subchannels to isolate them at the receiver using the conventional filters. this arrangement does not achieve effective use of bandwidth. a much more efficient use of bandwidth can be obtained with a parallel system if the spectra of the individual subchannels are permitted to overlap, as shown in fig.(1-b). with the addition of coherent detection and the use of subcarrier separated by the reciprocal of the signal element duration, independent separation of the multiplexed subcarriers is possible. if this condition is satisfied then this ofdm system will achieve orthogonality among its consistent subcarriers [4]. consider the system in fig.(2). the transmitted spectral shape is chosen so that intercarrier interference (ici) does not occur; that is, the spectra of the individual subcarriers are maximum at their frequency and zero at other subcarrier frequencies. the n serial data elements (spaced by t=1/r where r is the symbol rate) modulate n subcarrier frequencies, which are then frequency division multiplexed. the symbol duration (ts) has been increased to (nt), which makes the system less susceptible to delay spread impairments [5]. the subcarrier frequencies are separated by the multiples of (1/nt) so that, with no signal distortion in transmission, the coherent detection of a signal element in any subcarrier of ofdm system gives no output for a received element in any other subcarriers. hence, the n received signal elements, corresponding to the n subcarriers of ofdm system, are said to be orthogonal. so, no further filtering is needed to separate the different subcarriers. in other words, the power density spectrum has a central positive peak at an individual carrier frequency, and zeros at all other subcarrier frequencies [5]. fc1 fc2 fc3 fc4 subchannel subchannel subchannel subchannel 1 2 3 4 a m p li tu d e (a) non-overlapped system (b) overlapped system fc1 fc2 fc3 fc4 subchannel subchannel subchannel subchannel 1 2 3 4 frequency a m p li tu d e fig.1. transmitted signal spectrum of fdm system. frequency a m p li tu d e ahmed k. hassan al-khwarizmi engineering journal, vol.4, no.4, pp 82-90 (2008) 84 3. implementation of ofdm using fast fourier transform (fft): the main objections to the use of parallel systems are the complexity of the equipment required to implement the parallel system and the possibility of severe mutual interference among subchannels when the transmission medium distorts the signal. system design is greatly reduced by eliminating any pulse shaping and demodulated by using discrete fourier transform (dft) to implement the modulation process [6]. the transmitted ofdm symbol waveform can be represented as:            )2exp()(re)( 1 0 tfjkdts k n k  where d(k) is the modulated data symbol, fk is the subcarrier frequency of k th subcarrier which is equal to (fc+k∆f). m o d u lato r serial to parallel conversion m u ltip lex er tfj e 02 tfj e 12 tnfj e 12  d(0) d(1) d(n-1) d(k) s(t) serial binary input t=1/r (a) parallel to serial conversion )(d̂ 1 )(d̂ 0 )n(d̂ 1 tfj e 02 tfj e 12 tnfj e 12  r(t) d em o d u lato r (b) fig. 2. basic ofdm system (a). transmitter (b). receiver  st 0  st 0  st 0 ahmed k. hassan al-khwarizmi engineering journal, vol.4, no.4, pp 82-90 (2008) 85 fc is the carrier frequency, ∆f is the subcarrier spacing (bandwidth) equal to (1/nt) t is the symbol time duration. n is the subcarriers number. this expression represents the passband ofdm signal. the equivalent complex baseband notation is given by:    )2exp()()( 1 0 tfkjkdts n k  if the signal is sampled at a rate of (t), then (t=nt), and for orthogonality ∆f=(1/nt), then equation (2) can be rewritten as: )3...( )2exp()()( 1 0    nnkjkdns n k  equation (3) is exactly the inverse discrete fourier transform (idft) of data sequence d(k). all operations that occur in the transmitter are reversed in the receiver. further reductions in complexity are possible by using the fast fourier transform (fft) algorithm to implement the dft. to eliminate the intersymbol interference (isi) almost completely, a guard time is introduced for each ofdm symbol. the guard time is chosen larger then the expected delay spread such that multipath components from one symbol can not interfere with the next symbol. the guard time could consist of no signal at all. however, the problem of intercarrier interference (ici) would arise. ici is a crosstalk between different subcarriers, which means that they are no longer orthogonal. to eliminate ici, the ofdm symbol is cyclically extended in the guard time, which is done by taking symbol period samples from the end of ofdm symbol and appending them to the start of ofdm symbol. 4. mathematical formulation of an ofdm signal and papr: if n is the number of sub carriers in an ofdm, then n distinct mapped qpsk symbols are grouped as a set x={x1 , x2 ,….,xn}. each value in a set is a complex value. an ifft of vector x would result in n evenly spaced sample values of an ofdm signal in time domain. if the samples are shown as x={x1, x2, …., xn} then each sample can be derived as [7]: )4...( 1 2   n i kij ik exx  each ofdm symbol has time duration t, is relatively very large compared to symbol duration of a single carrier system. orthogonal condition is attained by maintaining the sub carrier frequency spacing of 1/t. at the receiver end sampling, the received signal and applying fft followed by de_ mapping can demodulate the ofdm signal. the discrete papr of an ofdm signal is defined as [7]: )5...( }{ )max( )( 2 2  k k xe x xpapr where e{.} is the mean of the sequence. the discrete papr is a good approximation of exact papr if the sampling rate is high enough. this can be assured by over-sampling the ofdm signal before computing discrete papr. it has been shown that over-sampling by 4 will make discrete papr sufficiently reliable. 5. clipping processing technique: clipping method is the simplest way to reduce papr. this method is based on clipping the signal, such that the peak amplitude becomes limited to some desired maximum level. this technique is performed by passing the ofdm modems output base band signal through a digital limiting device prior to transmitter stage, as shown in fig.(3). the disadvantage of this method is the distortion of the ofdm signal amplitude and this problem can be solved by optimum choice of clipping level for each designed system. this made depending on the analysis of system performance at different clipping level, such that the minimum papr with good ber performance can be achieved [2]. ahmed k. hassan al-khwarizmi engineering journal, vol.4, no.4, pp 82-90 (2008) 86 6. iterative processing technique: fig. (4) shows the transmitter structure of ofdm with iterative processing method. modulated data are converted from serial to parallel, and then it is transformed to ofdm symbol in time domain by ifft. the peak power components which exceed permission papr in each ofdm are detected by peak detector to obtain s(n). s(n) is defined by: )6...( |)(|. |)(| )( )( |)(|)( )(           nx nx nx nx nxnx ns where x(n) is the n th sampling signal in each ofdm symbol and λ is the desired papr threshold. signal s(n) is then fft to obtain the frequency domain peak cancellation signal s(k) as      1 0 2 )( 1 )( n n n knj ens n ks  , )7...( 10  nk the peak cancellation signals s(k) is then subtracted from the input modulated symbols, so that the peak generation is avoided . the target papr lower bound can not be attained in single execution, therefore require iteration, as the name implies. modulation qpsk s/p ifft tx data fig.3. block diagram of ofdm transmitter using clipping method. p/s output signal limiter s/p ifft p/s peak detector fft s(k) s(n) fig.4. iterative processing structure at the ofdm transmitter. ahmed k. hassan al-khwarizmi engineering journal, vol.4, no.4, pp 82-90 (2008) 87 7. experimental results: simulation of papr reductions using clipping and iterative processing method are carried out using technical (matlab) package. fig.(5) shows flowchart of papr using iterative processing. papr reduction calculation conducted by computer simulation are plotted in fig.(6), fig.(7), fig.(8) and fig.(9). these graph are generated from 10000 randomly distributed symbols with qpsk modulation and ofdm sub carriers are generated from fft points of 1024. fig.(6) shows ber performance degradation using clipping method assuming the channel is awgn. fig.(7), fig.(8) and fig.(9) show ber performance degradation using iterative start modulate the input stream using qpsk convert the signal from serial to parallel (s/p) apply ifft calculate papr calculate the peak detector depending on the threshold value apply fft to the output peak detector signal to obtain the peak cancellation signal subtract the peak cancellation signal from the input modulated signal end of iteration? compute papr and ber end fig. 5. flowchart of papr using iterative processing. no yes ahmed k. hassan al-khwarizmi engineering journal, vol.4, no.4, pp 82-90 (2008) 88 processing method for iteration 1, iteration 2, and iteration 3 respectively. ber degradation depends on the iteration time; large iteration caused deep ber degradation compared with clipping method and iterative processing method gives high papr reduction compared with clipping method. fig.(10) shows comparison of ber performance between different iteration for λ=0.9 of maximum value of ofdm coefficients. it is shown that at ber of 10 -4 the total degradation is about 4db after three time iteration. fig.7. ber performance for qpsk ofdm with iterative1. papr=6 db papr=7 db fig.6. ber performance for qpsk ofdm with clipping method and the channel is awgn. papr=9 db papr=8 db papr=7.5 db fig.8. ber performance for qpsk ofdm with iterative2. papr=6.5 db papr=5.5 db fig.9. ber performance for qpsk ofdm with iterative3. papr=5.46 db papr=4.5 db ahmed k. hassan al-khwarizmi engineering journal, vol.4, no.4, pp 82-90 (2008) 89 8. conclusions: the following points are concluded from the simulation results: 1iterative processing method gives higher papr reduction compared with clipping method (i.e., papr is about 7.5 db for clipping method and about 4.5 db for iterative method when  =0.8 max(ofdm), therefore there is gain about 3 db with suitable degradation in ber). 2iterative processing method using one iterative gives minimum ber degradation compared with two and three iterative. 3iterative processing method using three iterative gives higher papr reduction compared with one and two iterative. 4threshold value (λ=0.9*max (ofdm)) gives minimum ber degradation compared with threshold value (λ=0.8*max (ofdm)). 5threshold value (λ=0.8*max (ofdm)) gives higher papr reduction degradation compared with threshold value (λ=0.9*max (ofdm)). 9. references: [1] g. redaelli et al., "analysis of two digital adaptive pre-correctors for non-linearity in ofdm systems", proceedings of 1999 ieee international conference on communications, vol.1, 172-7, june 1999. [2] r. van. nee and r. prasad, "ofdm for wireless multimedia communications", artech house, 2000. [3] seung hee han and jae hong lee, "an overview of peak to average power ratio reduction techniques for multicarrier transmission", ieee wireless communication, april 2005. [4] cimini, leonard, "analysis and simulation of digital mobile channel using orthogonal frequency division multiplexing ", ieee trans. comm.33, no.7, july 1985, pp665675. [5] louis litwan and michael pugel, " the principles of ofdm", rf signal processing, january 2001. [6] mohanad e. al-madi, "hf data transmission using orthogonal frequency division multiplexing ", msc thesis, college of engineering, al-mustansirya university,2004. [7] azhar qasim taha," performance analysis of icc technique for ofdm papr reduction and its application over btc", master degree project stockholm, sweden, 2006. fig.10. comparison of ber performance between different iteration for λ=0.9*max(ofdm). (2008 )90-82، صفحت 4، العذد 4 هجلت الخىارزهً الهنذسٍت الوجلذ احوذ كاهل حسٍن 90 تقلٍل نسبت القذرة العضوى الى القذرة الوعذلت الشارة هقسن التردد العاهىدي باستخذام طرٌقتً التقٍٍن والوعالجت الوتكررة احوذ كاهل حسن انجايعت انخكُٕنٕجٛت/ قسى انُٓذست انكٓزٔيٛكاَٛكٛت الخالصت ( ofdm)احذٖ انًشاكم انًًّٓ فٙ يُظٕيت االحصاالث انالسهكّٛ باسخخذاو انخضًٍٛ انًخعذد انخحًٛم يثم يقسى انخزدد انعًٕد٘ انًخعذد ٔانخٙ حسبب حقهٛم انقذرة انًزسهت ٔكذنك حقهم انًذٖ انذُٚايٛكٙ نخحٕٚم (papr )ْٙ يشكهت َسبت انقذرة انعظًٗ انٗ انقذرة انًعذنت (adc ) ٔ(dac) ْذِ انًشكهّ يًّٓ . ٔانخٙ حٕد٘ انٗ حقهٛم انقذرة انًكبزة فٙ االرسال ٔانخٙ حٕثز بذٔرْا عهٗ يعذل انًعهٕياث انًُجزة ٚعخبز يٍ االيٕر انًًّٓ انخٙ حزٚذ كفائت خذيت احصاالث paprفٙ يحطاث انًٕباٚم انخٙ حغذ٘ بطارٚت ٔبعًز اطٕل ٔنذنك حقهٛم ْذِ انطزٚقت حسخُذ عهٗ انخقهٛى ٔ انًعانجت انًخكزرةنخقهٛم . (ofdm) الشارة paprفٙ ْذا انبحث حى اسخخذاو طزٚقت فعانت نخقهٛم .انًٕباٚم بعذ اجزاء انخقهٛى يٍ االشارة االصهٛت حخى فٙ يجال انخزدد ٔنٛس فٙ يجال انزيٍ كًا papr فٙ يجال انزيٍ ٔنكٍ عًهٛت طزح paprقًٛت . berيع ٔجٕد اضًحالل قهٛم فٙ قًٛتpapr أٌ انُخائج نٓذِ انطزٚقت اعطج قذرة عهٗ حقهٛم .فٙ طزق انخقهٛى انشائعت finite element analysis of stresses in a welded pipe al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 5, no. 1, pp 33-41 (2009) investigation of thermal stress distribution in laser spot welding process osamah f. abdulateef department of manufacture operation engineering / al-khwarizmi college of eng. / university of baghdad (received 14 december 2008; accepted 19 march 2009) abstract the objective of this paper was to study the laser spot welding process of low carbon steel sheet. the investigations were based on analytical and finite element analyses. the analytical analysis was focused on a consistent set of equations representing interaction of the laser beam with materials. the numerical analysis based on 3-d finite element analysis of heat flow during laser spot welding taken into account the temperature dependence of the physical properties and latent heat of transformations using ansys code v.10.0 to simulate the laser welding process. the effect of laser operating parameters on the results of the temperature profile were studied in addition to the effect on thermal stresses and dimensions of the laser welded workpiece which showed good correlations between analytical and numerical results. it was found that the temperature gradients during laser welding are usually very large and it was viewed that very high temperature at the center of the workpiece, and is decreased very significantly as propagating along the radial direction. also it found that the thermal residual stresses around the laser spot due to plastic strains were very small and localized within 1.0 mm range. it is concluded that the laser welding process is effective to reduce the welding residual stress. the stresses along the lateral direction of the workpiece changed from compression at the spot under the laser beam and tension away from the spot at the end of welding to tension at the spot under the laser beam and compression away from the spot when it cooled, which are in a good agreement with the published results. keywords: laser-spot welding, residual stress, non-linear thermal stress. 1. introduction: laser welding represents a delicate balance between heating and cooling within a spatially localized volume to produce the liquid melt pool by absorption of incident radiation, allow it to grow to the desired size, and then to propagate this melt pool through the solid interface eliminating the original seam between the components to be joined. laser beam welding has a number of desirable attributes. the heat affected zones are characteristically smaller and narrower than those produced using conventional welding techniques and distortion of the workpiece is reduced. during laser spot welding, an intense beam is focused onto a small area. the material under the beam rapidly melts and may partly vaporise, leaving behind a small vapour filled crater, which enhances the absorptivity of the incident beam. the molten front extends more in the thickness than in the width direction if the laser power is sufficiently high. this can lead to a parallel sided molten pool and heat transfer occurs predominantly via radiative and convective modes through the vapour and molten material. numerical simulations of a laser welding process have been a major topic in welding research for several years. the results of simulations can be used to explain physical essence of some complex phenomena in the laser welding process explicitly and can be also used as the basis for optimization of the process. simulations of the laser welding process enable estimation of transient stresses, residual stresses, and distortions. these can be used to evaluate structural misalignments and unexpected failures due to overstressing caused by the superposition of in-service loads and welding induced residual stresses. however, the simulation of the welding process is not an easy task since it involves osama f. abdulateef al-khwarizmi engineering journal, vol. 5, no. 1, pp 33-41 (2009) 34 interaction of thermal, mechanical, and metallurgical phenomena. for the study of stress distributions in laser welding process, early researches include the consideration of the thermoelasticity problem due to a moving heat source [1], development for the transient surface stress and displacement due to line heat sources in terms of bessel functions [2], and the calculation of thermal stresses on an infinite slab caused by a moving square heat source on the surface [3]. more recently, an analytical solution for a semiinfinite plane subjected to a moving gaussian heat source was obtained in terms of bessel functions and exponential integrals [4]. an explicit formula for the shape of the deformed target surface under laser irradiation was obtained as a function of the deposited gaussian energy distribution [5]. furthermore, the numerical model of the thermal stresses generated by a moving elliptical weld pool in the welding of thin metal sheets were developed [6], and the stresses along the weld direction and the distortion of the workpiece from the laser welding process were evaluated using a mellin-transform technique, where the considerations were restricted to the plane linear thermoelastic model in order to obtain the basic mathematical formula for the transient change in stresses, and the final results were expressed in terms of a convolution integral and illustrated by numerical calculations for the point heat source [7]. a number of analytical and numerical models of laser welding processes have been used to evaluate temperature and stress distribution during the welding process, as well as corresponding residual stresses and final distortions of structural components. these include analytical models [8], two-dimensional finite element models [9], and three-dimensional finite element models [10]. however, not all of parameters influencing the welding process, including microstructural changes due to phase transformation, heat flux simulation, and variation of thermal and mechanical material properties with temperature, were taken into account in the simulations listed above. [11], investigated the transient thermal and stress analyses of a laser spot-welded joint using nonlinear finite element method, and since the study was limited to the thermoelastic stresses, it was found that the stresses and deformations were overestimated. laser materials processing utilizes the high power density provided by the laser beam, which is focused on the workpiece. as a result, the workpiece material experiences heating, melting, and possible vaporization and re-solidification. understanding the temporal evolution of the temperature field during laser material interaction is one of the most significant factors in achieving a desired quality of processing. the thermal history is required to determine dimensional changes in the machined part, the related stresses, phase transformations taking place, and the final metallurgical microstructures. in order to achieve a satisfactory study of the laser welding process, it is first of all necessary to know the temperature distributions resulting from the irradiation of the laser beam. the next step that must be addressed is to use the fundamental equations of linear thermo-elasticity to arrive knowledge of the distribution of stress in the elastic material under certain boundary conditions. once a combined understanding of the temperature and stress distribution is achieved it is possible to identify domains in which the stresses may have a value above the yield point of the material at a given temperature, as well as regions where possible phase changes can occur for the particular material. 2. theoretical aspects: the coupling of laser radiation into a metal to produce the localized heating required for spot welding involved a delicate balance among many parameters. some of these parameters, such as laser intensity, pulse shape, and beam polarization, are under the control of the operator, whereas others, such as metal reflectivity, thermal conductivity, and heat capacity, are not. fig. 1. transverse section of thermal model [13] under conduction limited conditions, the onset of surface melting can be estimated from the simple model (see figure 1). the temperature at the center of the beam focus(r =0) is: osama f. abdulateef al-khwarizmi engineering journal, vol. 5, no. 1, pp 33-41 (2009) 35 ... (1) where k is the thermal conductivity, k is thermal diffusivity, w is the gaussian beam radius, t0 is the ambient temperature, and t is time. if t (0, t) =tm, the melting temperature, then the laser beam intensity, im(0), required to produce melting in time t can be obtained with equation 1. an estimate of the depth of penetration, zm, of the weld pool under spot welding conditions in which melting is included can be obtained, when considered tm as the time at which t(z=0)=tm, as [12]: … (2) where ρ is the density of the melt and lm is the latent heat of fusion. equation 2 will be strictly valid only when tm<8k/w 2 . in order to account for the thermomechanical effect during the heating process, the energy transport equation for a deformable solid body can be written for the specific enthalpy as … (3) the equation describing the energy transport due to electron-photon interaction can be written as … (4) combination of equations 3 and 4 yields … (5) equation 5 is the general energy transport equation, which includes the thermomechanical effect. i.c's: t=0, t=0 and u=0, since the laser pulse length and heating duration are short, there is no convection or radiation losses are considered from the surface, therefore b.c's at t>0 and at the surface, 0)    surface x t , at t>0 and x = y = z = α, t= 0 and u= 0. during laser materials processing, the heating is localized and therefore, a very large temperature variation occurs over a small region. owing to this temperature gradient, large thermal stresses are generated in the substrate, which can lead to the defects in the material such as the formation of cracks and fractures in the material. the stress is related to strains by [14]: {σ}= [d] {ε e }, ... (6) where {σ} is the stress vector, and [d] is the elasticity matrix. {ε e }= {ε}-{ε th }, …(7) where {ε} is the total strain vector and {ε th } is the thermal strain vector. equation 7 may also be written as {ε}=[d] -1 {σ}+{ε th } … (8) but {ε th } =α e δt= α e (t-tref) ... (9) where tref is the reference temperature at t=0. the principle stresses (σ1, σ2, σ3) are calculated from the stress components by the cubic equation. the von mises or equivalent stress, σ ' , is computed as … (10) the equivalent stress is stress is related to the equivalent strain through σ ' =e ε ' …. (11) where ε ' is the equivalent strain. the boundary conditions for stresses are: since there is no surface tractions are involved in the problem under consideration the corresponding boundary and initial conditions are introduced: at t=0, σ=0, at t>0 and at surface, σsurface=0, at t>0 and x=y=z=α, σ=0. 3. finite element modeling procedures: the form of the representation used for the laser beam has a significant effect on the results of numerical models of the laser beam welding process. a gaussian representation of the laser beam, assuming heat input only on the top surface of the material, may not lead to correct results, especially for high power lasers that penetrate rapidly some distance into the material thickness, 2/1 2 1 2/1 ) 8 (tan )2( )0( ),0( w kt k wai ttt   )( 16.0 )( m m m tt l ai tz   ).()(. u t c t t cq e p p          )exp(). 2 ( 2 ). 2 (. x surf it tf pc tkq             )exp(.)(. 2 2 . 2 x surf iu te t tf t t t              ])()()[( 2 1 2 13 2 32 2 21 '   osama f. abdulateef al-khwarizmi engineering journal, vol. 5, no. 1, pp 33-41 (2009) 36 resulting in welds of high depth to width ratio. the present work is thus aimed at a heat transfer analysis following the double ellipsoidal representation of the laser beam, as this typically incorporates volumetric heat input from a heat source. the temperature dependence of the material properties, phase change phenomena, and convective and radiative heat losses from all the surfaces of a sheet are considered. the heat transfer analysis is therefore axisymmetric, with the y axis defined as the axis of symmetry. the volumetric heat input due to the laser is represented by adapting equation (12) for a stationary heat source [13], .... (12) where q is taken to be the incident laser power multiplied by the energy transfer efficiency (absorptive), a is the focal radius of the laser beam, b is the sheet thickness. the fe analysis was carried out in two steps: 1nonlinear (material properties depend on temperature) transient thermal analysis using three modes of heat transfer: conduction, convection, and radiation; was conducted first to obtain the global temperature history generated during and after welding process. 2stress analysis was then developed with the temperatures obtained from the thermal analysis used as loading to the stress model. the general purpose fe package ansys v10.0 was used for both thermal and stress analysis performed sequentially. the mesh used in the stress analysis was compatible to that in the thermal analysis. figure 2 shows model geometry and the representative mesh. fig.2. model geometry and meshes 4. results and discussions the present study is based on calculated geometric and material data for laser spot welds in a single sheet. the heat source was a laser with a beam spot diameter of 1.0 mm focused normally onto the top surface of a 2.0 mm thickness low carbon steel sheet. three levels of beam power, namely 1.0, 1.5, and 2.5 kw, and on-times varying in the range 0.15 – 2.65 s were considered. to model the results, a rectangular region of 15 mm (width) by 2 mm (thickness) is finely discretised (meshed) into divisions of 0.1 mm along the thickness direction. along the width direction, a division of 0.1 mm is used up to a distance of 5 mm, beyond which a division of 0.2 mm is used for the remainder of the length. 3d 20-node elements are used. the time span of the transient analysis includes the on-time of a ) 2 2 3exp() 2 2 3exp( 2/32 36 ),( b y a x ba q yxq   osama f. abdulateef al-khwarizmi engineering journal, vol. 5, no. 1, pp 33-41 (2009) 37 single laser pulse and the subsequent cooling stage. the analysis is carried out through a number of small time steps, each time step being 0.001 s. within each time step, a number of iterations are performed to achieve a convergence criterion of 1% (the difference in nodal temperature between two successive iterations). figures 3(a,b) show the temperature dependent thermal and mechanical material properties used in the calculation. during the analysis, whenever the temperature of a node exceeds the boiling point of the steel (2800°c), it is allowed to remain in the mesh at the boiling temperature and is not considered further in the analysis until cooling starts after removal of the laser beam. -a -b fig.3. [15] material properties with temperature avariation of thermal material properties with temperature. bvariation of mechanical material properties with temperature -a along radial distance -balong weld depth fig.4. temperature distribution 0 500 1000 1500 2000 2500 3000 0 0.0002 0.0004 0.0006 0.0008 0.001 0.0012 0.0014 0.0016 0.0018 0.002 weld depth, m 1 kw 1.5 kw 2.5 kw t em p er at u re , o k o k 0 500 1000 1500 2000 2500 3000 0 0.001 0.002 0.003 0.004 0.005 0.006 0.007 0.008 0.009 0.01 radial distance, m 1 kw 1.5 kw 2.5 kw t em p er at u re , o k o k osama f. abdulateef al-khwarizmi engineering journal, vol. 5, no. 1, pp 33-41 (2009) 38 in figures 4(a,b) the maximum temperature for laser powers of 1.0, 1.5, 2.5 kw and an ontimes of 0.15 sec are compared. the weld width and penetration are estimated along the horizontal and vertical direction respectively. it can be shows that the weld dimensions do not changes significantly as the laser power is increased from 1.0 to 1.5 kw for an on-time 0.15 sec. in contrast, an increase in laser power to 2.5 kw shows a marked increase in penetration from approximated 0.5 mm (both at 1.0 and at 1.5 kw) to 1.0 mm at (2.5 kw). this is further evident as the on-time is increased from o.15 to 0.225 sec at 2.5kw laser power (see figure 5). -aalong radial distance -balong weld depth fig.5. temperature distribution the temperature gradients during laser welding are usually very large, due to the high power density, and small local area provided by the laser. figures 6 and 7 show the large temperature gradient at the workpiece radial distance at a laser power of 2.5kw, and it can be viewed that very high temperature occur at the center of the workpiece, and is decreased very significantly as propagating along the radial direction, and for nodes that more1.5 m.m away from the center, the temperature drop down to very close to room temperature indicating that most of the heat affected zone are localized within the 1.5 m.m range. fig.6. temperature distribution along radial distance fig.7. temperature distribution during laser spot welding for stress calculation, the temperature fields at the various time steps are then used as an input to the mechanical analysis, von mises stress was calculated. the maximum von mises stress was about 380 mpa, while the yield strength of low carbon steel is about 290 mpa, indicating that the workpiece would undergo plastic deformation. the thermal residual stresses around the laser spot due to plastic strain can be calculated from figure 8 at yield strength value. it was found that the residual stresses were very small and localized within 1.0 mm range in radial distance and 0.5mm range in depth; these values are very small compared with 4 mm range in radial distance for resistance spot welding process[16]. 0 500 1000 1500 2000 2500 3000 0 0.001 0.002 0.003 0.004 0.005 0.006 0.007 0.008 0.009 0.01 radial distance, m t=0.15 sec t=0.65 sec t=1.15 sec t=1.65 sec t=2.15 sec t=2.65 sec t em p er at u re , o k o k 0 500 1000 1500 2000 2500 3000 0 0.001 0.002 0.003 0.004 0.005 0.006 0.007 0.008 0.009 0.01 radial distance, m t=0.15 sec t=0.165 sec t=0.18 sec t=0.225 sec t em p er at u re , o k o k 0 500 1000 1500 2000 2500 0 0.0002 0.0004 0.0006 0.0008 0.001 0.0012 0.0014 0.0016 0.0018 0.002 weld depth, m t=0.15 sec t=0.165 sec t=0.18 sec t=0.225 sec t em p er at u re , o k o k osama f. abdulateef al-khwarizmi engineering journal, vol. 5, no. 1, pp 33-41 (2009) 39 -aalong radial distance -balong weld depth fig.8. von mises thermal stress distribution after laser spot welding in laser spot welding, a weldment is locally heated by intense beam which focused on small area. due to non-uniform temperature distribution during the thermal cycle, incompatible strains lead to thermal stresses. these incompatible strains due to dimensional changes associated with solidification of the weld metal, metallurgical transformations, and plastic deformations, are the sources of residual stresses. the stresses along the lateral direction of the workpiece changed from compression at the spot under the laser beam and tension away from the spot at the end of welding (t=2.65 sec) to tension at the spot under the laser beam and compression away from the spot when it cooled (t=400 sec), which are a good agreement with the published results[11,15], see figure 9. fig.9. thermal stress distribution during and after laser spot welding 0 50 100 150 200 250 300 350 400 0 0.0002 0.0004 0.0006 0.0008 0.001 0.0012 0.0014 0.0016 0.0018 0.002 weld depth, m numerical theoretical t h er m al l s tr es s, m p a m p a 0 50 100 150 200 250 300 350 400 0 0.0002 0.0004 0.0006 0.0008 0.001 0.0012 0.0014 0.0016 0.0018 radial distance, m numerical theoretical t h er m al s tr es s, m p a m p a -400 -300 -200 -100 0 100 200 300 400 0 0.0002 0.0004 0.0006 0.0008 0.001 0.0012 0.0014 0.0016 0.0018 radial distance, m t=2.65 sec t=400 sec t h er m al s tr es s, m p a osama f. abdulateef al-khwarizmi engineering journal, vol. 5, no. 1, pp 33-41 (2009) 40 5. conclusions: an analytical and finite element analyses have been investigated to simulate the laser spot welding process on a low carbon steel sheet. the analytical analysis was focused on a set of equations representing interaction of the laser beam with materials. the numerical analysis based on 3-d finite element analysis of heat flow during laser spot welding taken into account the temperature dependence of the physical properties and latent heat of transformations using ansys code v.10.0. the effect of laser operating parameters on the results of the temperature profile, thermal stresses, and dimensions of the laser welded workpiece were studied which showed good correlations between analytical and numerical results. we conclude that: 1the temperature gradients during laser welding are usually very large and it was viewed that very high temperature at the center of the workpiece, and is decreased very significantly as propagating along the radial direction. 2the thermal residual stresses around the laser spot due to plastic strains were very small and localized within 1.0 mm range. 3laser welding process is effective to reduce the welding residual stress. 4stresses along the lateral direction of the workpiece changed from compression at the spot under the laser beam and tension away from the spot at the end of welding to tension at the spot under the laser beam and compression away from the spot when it cooled. 6. references: [1] w.nowacki, 1962, thermoelasticity, addison-wesely, reading, ma. 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[16] nabeel k. alsahib, somer m. nacy, faiz f. mustafa, 2008, “spot welding residual stresses assessment using nonlinear numerical technique”, journal of eng., college of eng., university of baghdad, vol.14, no.1:2202-2215. 200 )41-33، صفحة 1، العذد 5مجلة الخوارزمي الهنذسية المجلذ اسامة فاضل عبذ اللطيف 9) 41 توزيع األجهادات الحرارية في عملية اللحام النقطي بالليسر أستقصاء أسامة فاضل عبذ اللطيف خايؼت بغذاد \ كهٍت انهُذست انخىاسصيً \ قسى هُذست ػًهٍاث انخصٍُغ الخالصة انداَب انخحهٍهً أػخًذ . ٌهذف هزا انبحث انى دساست ػًهٍت انهحاو انُقطً بانهٍضس نصفائح انكاسبىٌ انًُخفط انفىالرٌت ححهٍهٍا و ػذدٌا أيا انداَب انؼذدي فقذ أسخُذ ػهى ححهٍم ػُصش ثالثً األبؼاد . ػهى يدًىػت ثابخت يٍ انًؼادالث انخً حًثم انخفاػم بٍٍ شؼاع انهٍضس وانًؼذٌ نخًثٍم انحشاسة انًخىنذة أثُاء ػًهٍت انهحاو انُقطً أخزٌٍ بُظش األػخباس أػخًاد انخصائص انفٍضٌائٍت وانحشاسة انكايُت ػهى دسخاث انحشاسة , حى فً هزا انبحث دساست حأثٍش يخغٍشاث شؼاع انهٍضس ػهى حىصٌغ دسخاث انحشاسة. يخؼذد األغشاضansys 10.0بأسخخذاو بشَايح وقذ حى يالحظت حصىل . نقذ الحظُا يٍ خالل انُخائح وخىد أسحباغ خٍذ بٍٍ انداَبٍٍ انخحهٍهً وانؼذدي. وأبؼاد يُطقت انهٍضس, األخهاد انحشاسي كزنك . أسحفاع كبٍش خذا فً دسخاث انحشاسة أثُاء انهحاو بانهٍضس فً يشكض انبقؼت ثى ٌبذأ بانخُاقص بصىسة كبٍشة كهًا أبخؼذَا باألحداِ انشؼاػً يههًٍخش وهزا ٌذل 1.0حًج يالحظت حىنذ أخهاد حشاسي يخبقً حىل بقؼت انهٍضس بسبب األَفؼال انهذٌ يىصػا فً يُطقت ظٍقت خذا الحخداوص اٌعا حى األسخُخاج بأٌ اإلخهاد ػهى غىل اإلحّداِ . ػهى أٌ ػًهٍت انهحاو بانهٍضس فؼانت نخخفٍط األخهاداث انحشاسٌت انًخبقٍت َخٍدت ػًهٍت انهحاو انداَبً نهقطؼت انًهحىيت قذ حغٍّش يٍ األخهاد األَعغاغً فً انبقؼت ححج شؼاع انهٍضس وأخهاد شذ بؼٍذا ػٍ انبقؼت فً نحظت َهاٌت انهحاو إنى أخهاد شذ فً انبقؼت ححج شؼاع انهٍضس وأخهاد أَعغاغ بؼٍذا ػٍ انبقؼت ػُذيا بّشدث, وهزا ٌخىافق يغ األدبٍاث انًُشىسةانخً نها ػالقت . بانًىظىع (microsoft word \322\355\344\310 \307\341\336\355\323\355120130) al-khwarizmi engineering journal al-khwarizmi engineering journal,vol. 13, no. 3, p.p. 120130 (2017) travel time prediction models and reliability indices for palestine urban road in baghdad city zainab ahmed al-kaissi department of highway and transportation engineering/ college of engineering/ al-mustansiriyah university email:dr.zainabalkaissi77@uomustansiriyah.edu.iq (received 31 october 2016; accepted 29 january 2017) https://doi.org/10.22153/kej.2017.01.007 abstract travel time estimation and reliability measurement is an important issues for improving operation efficiency and safety of traffic roads networks. the aim of this research is the estimation of total travel time and distribution analysis for three selected links in palestine arterial street in baghdad city. buffer time index results in worse reliability conditions. link (2) from bab al mutham intersection to al-sakara intersection produced a buffer index of about 36% and 26 % for link (1) al-mawall intersection to bab almutham intersection and finally for link (3) which presented a 24% buffer index. these illustrated that the reliability get worst for link (2), (1) and (3) respectively during the peak period. extra delay is observed on link(1), (2) and (3) in terms of 95% percentile travel time of about (301.9, 219.4, and 193.8)sec. for link (1, 2 and 3) respectively. higher value for 95% travel time is obtained for link (1). travel time index (tti) of 4.2 %, 4.9% and 4% is obtained for link (1, 2 and 3) respectively. maximum value for delay per km that obtained for link (1) which is about 266 sec/km and 268 sec./km for link (3) and 244 sec/km for link(2). different predicted model for the three studied links of palestine street have been developed based on the obtained field data. a best fit is presented as compared the predicted models with the observed field travel time data for all the models of studied links which illustrated that the predicted model can present the actual field data. keywords: delay, buffer index, travel time, predicted model, reliability, urban arterial. 1. research objective the aim of this research is the estimation of total travel time and distribution analysis for three selected links in palestine arterial street in baghdad city which is considered as one of the most important residential and commercial area in baghdad city due to dramatic change that produce potential pressure on daily trip generation and attraction. a statistical methods is needed to model travel time distribution on which reliability indices measurements including buffer index, buffer time and 95% percentile travel time were developed based on. 2. introduction the travel time of urban arterial in urban city played an important role in measuring the performance of traffic transportation system. different studies are employed to model the distribution for travel time, [1], [2], [3] and [4] concluded for a lognormal distribution. polus, (1979) concluded for a gamma distribution; aldeek and eman (2006) proposed a weibull one [5], [6]. in taylor and susilawati (2012) and susilawati et.al. (2012) the burr distribution is adopted [7], [8]. federal highway administration (fhwa) has defined travel time reliability is as consistency or dependability in travel time as measure from day to day and across different times of the day [9]. the 95th percentile travel time and buffer index (bi) and zainab ahmed al-kaissi al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 120130 (2017) 121 planning time index (pti) considered as performance indicators for travel time reliability. travel time distribution and empirical based approach is the base for development of these indices. study of travel time reliability can help in understanding the variation in travel time and aid in transportation system management [10]. 3. study area and data collected 3.1. study area palestine street is one of the most important major arterial streets in baghdad city due to the majority of surrounded area of different mix land uses; commercial, educational and residential that provide potential pressure of generation and attraction additional daily trips. palestine street is located in the east of baghdad and it runs parallel to the west of army canal between al-mustansiriyah sequare through beirut square to the end of it at maysalone sequar; 6 divided lane carriageway 3-lane in each direction. figure (1) presents the three links that have been considered in this research namely as link(1); from al-mawall intersection to bab al-muatham intersection of 1.03 km length, link (2); from bab almuatham intersection to al-sachara intersection of 520m length, and link (3); from al-sachara intersection to beirut intersection of 620 m length respectively. the selected corridor for palestine street links passed through three signalized intersection (bab al-mutham intersection, al-sachara intersection and bairuit intersection) which also take into consideration their impedance and delay effect on travel time variability, reliability and distribution estimation. 3.2. data collection the field data are collected for the selected sections of palestine street for link (1), (2) and (3) respectively. congestion of traffic conditions is taking the major part during peak hours of the day from (12:00 to 4:00 p.m.) on monday 18 may and tuesday 19 may 2016 which is selected to study the variations of total travel time and travel delay time for each link in the selected site of palestine arterial street. gps essentials measurement equipped with cell phone is applied to compute travel time with a 30 set of data point is recorded at peak period from (12:00 to 4:00 p.m.) on each selected link corridor. figure (2) shows the control points for mapping the distance for acceleration and deceleration and starting of each link. 4. results and discussions 4.1. analysis of travel time in this research a consideration to congestion of traffic conditions is taking the major part during peak hours of the day from (12:00 to 4:00 p.m.) is preferred to study the variations of total travel time and travel delay time for each link in the selected site of palestine arterial street. fig. 1. study area urban arterial palestine street with selected three links. fig. 2. control points for deceleration, acceleration and stopping time measurement for studied links. zainab ahmed al-kaissi al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 120130 (2017) 122 a number of sample run of 30 is provided for each link in the south direction as described from the link name in the previous section of site selection. travel time analysis is required for measuring the performance and to have indication about the operation efficiency of palestine arterial corridor. figures (3), (4) and (5) clarified the variations of total travel time for each link including stop time and ( acceleration and deceleration time). figure (6) and (7) illustrated the travel time delay for each link; travel time delay estimated from total travel time minus ideal travel time for each link depend on posted speed limit and distance for each one. based on the obtained results shown in figures, link (1) from al-mawall to bab-almutham intersection produced the highest values for travel and delay time than other two links due to several reasons which can be referred to the surrounded of commercial, residential and educational mix land use that produced and attracted a large number of daily trips also its attributed to the traffic condition of the link itself which controlled by a check point at the start of the route for the link near almwaal intersection and cause excess delay during the peak hours reach about 5 minutes stopping causing the state of stop and slow moving conditions for vehicles. also its appeared that travel time varied during the time period and three maximum peak point at (12:001:00p.m), (1:30-2:30p.m) for all links and additional third peak point from (3:00-3:30) for link (1) were observed. maximum travel time of 518.5 sec. and delay time of 457sec. which is about 88% of travel time is lost due to condition of traffic congestion on link (1). also 238sec. total travel time for link (2) with delay time of 206sec. which is about 86% loss of travel time. and for link (3) a maximum travel time of 210 sec. and delay time of 172 sec. which is about 81.9% is lost due to delay congestion. gps essentials equipped with cell phone is applied to compute the delay component (acceleration, deceleration and stopped delay) of signalized intersections at the selected site by determining the critical points for acceleration , deceleration and stopping then measure the required time, see figure (2) of control points for each link. since hcm used equation for estimate the control delay which is applied for fixed signalized signal during the day and this not achieved in our locally signalized intersection which almost managed by police man that organized the traffic movement at signalized intersections otherwise its produced error in the obtained results and not matching the reality conditions. figures (8),(9) and (10) and tables (1), (2) and (3) presented the components of total delay for intersections in the selected site for ٣٠ sample run. it's clear that stopped delay compromise the major part of intersection delay for all links studied. also the acceleration time delay is higher than deceleration time as shown in the obtained results due to the conflict vehicles in the intersection which make the driver more alert during passing the intersection and this take more time to accelerate. fig. 3.total travel and delay time variations during peak period time for link (1). fig. 4. total travel and delay time variations during peak period time for link (2). fig. 5. total travel and delay time variations during peak period time for link (3). zainab ahmed al-kaissi al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 120130 (2017) 123 fig. 6. total travel time variations during peak period time for link (1), (2) and (3). fig. 7. travel time delay variations during peak period time for link (1), (2) and (3). table 1, delay component results for sample run of bab al-mutham intersection. run no. decelerat ion delay (sec.) acceleratio n delay (sec.) stopped delay (sec.) total delay (sec.) 1 17 30 60 107 2 20 35 61 116 3 23 20 68 111 4 22 38 60 120 5 15 29 58 102 6 21 45 58 124 7 18 32 100 150 8 22 30 45 97 9 15 28 65 108 10 19 14 43 76 11 10 38 115 163 12 22 18 73 113 13 28 36 38 102 14 20 28 42 90 15 15 42 102 159 16 16 43 102 161 17 8 20 43 71 18 18 45 102 165 19 22 30 150 202 20 30 25 141 196 21 20 40 60 120 22 17 38 60 115 23 20 43 45 108 24 15 35 103 153 25 21 20 116 157 26 22 44 60 126 27 20 38 60 118 28 20 31 47 98 29 18 16 63 97 30 15 24 44 83 fig. 8. proportions of total delay at intersection for link (1). table 2, delay component results for sample run of alsakara intersection. run no. deceleration delay (sec.) acceleration delay (sec.) stopped delay (sec.) total delay (sec.) 1 10 14 55 79 2 12 18 74 104 3 16 30 53 99 4 20 30 59 109 5 15 34 48 97 6 30 45 120 195 7 10 25 58 93 8 13 31 48 92 9 35 30 55 120 10 17 42 46 105 11 20 40 71 131 12 22 38 60 120 13 10 39 75 124 14 25 35 58 118 15 35 30 45 110 16 15 33 50 98 17 12 28 43 83 18 30 41 60 131 19 12 43 53 108 20 31 44 105 180 21 18 43 106 167 22 15 40 54 109 23 30 15 46 91 24 35 26 50 111 25 15 33 35 83 26 14 28 38 80 27 10 40 33 83 28 10 40 50 100 29 15 22 37 74 30 25 33 51 109 zainab ahmed al-kaissi al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 120130 (2017) 124 fig. 9. proportions of total delay at intersection for link (2). table 3, delay component results for sample run of bairuit intersection. run no. decelerat ion delay (sec.) acceleration delay (sec.) stopped delay (sec.) total delay (sec.) 1 12 40 40 92 2 20 43 55 118 3 16 50 60 126 4 21 48 50 119 5 20 60 53 133 6 30 47 75 152 7 38 70 80 188 8 24 55 60 139 9 13 48 91 152 10 18 65 62 145 11 12 44 45 101 12 14 30 37 81 13 10 70 40 120 14 25 35 58 118 15 17 30 45 92 16 15 28 50 93 17 12 55 43 110 18 23 56 60 139 19 18 70 53 141 20 15 56 105 176 21 25 44 70 139 22 10 49 54 113 23 22 30 46 98 24 20 55 60 135 25 15 28 95 138 26 14 47 38 99 27 18 22 45 85 28 10 39 46 95 29 14 50 36 100 30 25 30 51 106 fig. 10. proportions of total delay at intersection for link (3). 4.2. estimation of travel time distribution a 30 time data set of 15min. period is collected from field data using gps essentials equipped with cell phone as explained earlier to study the behavior of travel time variation on the three links (1), (2) and (3) that provide significant variation and multimodal shape due to the delay at signalized intersection and impedance due to traffic jam at the selected links at peak period. a normal, lognormal distribution are applied and fitted for the field data using (spss ver.21 statistical software). the graphical representation of histogram with normal curve for travel time distributions are shown in figures(10) to (12) for link (1), (2) and (3) in this research. the travel time distribution is fitted to normal for link (1) and , log-normal for link(2) and (3).based on normality test for shapiro-wilk column in tables (4) to (9) for link (1) ,(2) and (3) respectively which illustrated the significant level of p -value greater than 0.05. see table (10). a) normal distribution zainab ahmed al-kaissi al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 120130 (2017) 125 b) log-normal distribution fig. 10. normal and log-normal travel time distribution for link (1). table 4, descriptive statistics of normal distribution for travel time for link (1). table 5, test of normality for travel time distribution for link (1). table 6, descriptive statistics of normal distribution for travel time for link (2). table 7, test of normality for travel time distribution for link (2). a) normal distribution zainab ahmed al-kaissi al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 120130 (2017) 126 b) lognormal distribution fig. 11. normal and log-normal travel time distribution for link (2). table 8, descriptive statistics of normal distribution for travel time for link (3). table 9, test of normality for travel time distribution for link (3). a) normal distribution b) lognormal distribution fig. 12. normal and log-normal travel time distribution for link (3). table 6, test statistics for travel time distribution. 4.3. travel time model different predicted model for the three studied links of palestine street have been made based on the obtained field data as shown below: travel time for link (1): �� � 1.012�� � 67.87 � 0.939 � � 0.882 travel time for link (2): �� � 1.148�� � 30.464 � 0.967 � � 0.936 travel time for link (3): �� � 1.028�� � 30.432 � 0.985 � � 0.970 zainab ahmed al-kaissi al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 120130 (2017) 127 where: tt: total travel time (sec.) dt: delay time at signalized intersection (sec.) the summary of stepwise regression linear models are displayed in tables (7) to (9) respectively for link (1), link (2) and link (3). table 7, stepwise regression models summary for travel time of link (1). table 8, stepwise regression models summary for travel time of link (2). table 9, stepwise regression models summary for travel time of link (3). the validation of the three travel time model have been illustrated in figures (13) to (15) between the estimated travel time and observed travel time from field data. an additional data have been measured and not included in the model building to complete the process of validations. fig. 13. predicted travel time model versus field travel time for link (1). fig. 14. predicted travel time model versus field travel time for link (2). fig. 15. predicted travel time model versus field travel time for link (3). a best fit is presented as compared the predicted model with the observed field travel time data for all the models of studied links which illustrated that the predicted model can present the actual field data. the goodness of fit for predicted model and field observed data have been checked using chi-square test as shown in tables (10) to (12) for the study links. zainab ahmed al-kaissi al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 120130 (2017) 128 goodness of fit: chi-square test n=17 df=16 significant level α =0.05 predicted models �� ��������� link(1) 24.71978 26.296 link(2) 8.02577 26.296 link (3) 2.719857 26.296 for �� < ��������� ; there are no significant difference between predicted model and observed field data. 4.4. reliability measurement the variability of travel time effect on its reliability measurement and then produced extra arrival time which had a real cost. furthermore reliability of travel time is an important topics for increasing safety, quality life for road users, to produce less delay for their trips. also it's a good indicators for improving the overall system operations and management. buffer time reliability measure is explained as [9]: ������ !"�# $%& � '()* +��,�!)-.� /�01�. /-2� $3�,.&451��06� /�01�. /-2�$3�,.& 51��06� /�01�. /-2� $3�,.& ...(1) figure (15) presented the reliability measurement for palestine arterial street interms of the buffer time index for link (1), (2) and (3). increasing the buffer time index results in worse reliability conditions. link (2) produced a buffer index of about 36% and 26 % for link (1) and finally for link (3) which present a 24% buffer index. these illustrated that the reliability get worst for link (2) (1) and (3) respectively. also buffer time of (62 , 59, and 38 ) sec. for link(1, 2and 3) respectively is obtained based on average travel time for each link, that mean additional 62, 59 and 38 sec. buffer time is provided from the average value to ensure 95% arrive on time at the destination of arterial corridor for link (1),(2) and (3). also figure (16) show the 95% percentile travel time for observed links which presents the extra delay that perceived on each link (301.9, 219.4, and 193.8)sec. for link (1, 2 and 3) respectively. higher value for 95% travel time is obtained for link (1). figure (17) illustrated the travel time index which represent the average travel time divided by free flow time for the roadway study segments. a 4.2 %, 4.9% and 4% tti is obtained for link (1, 2 and 3) respectively. increasing the travel time index fig. 15. buffer time index for link (1), (2) and (3). fig. 16. 95% percentile travel time results for link (1), (2) and (3). greater than 1.0 meaning taking a longer travel time by about 420, 490 and 400 percent of free travel time to travel the three segment length respectively with the higher travel time index for link(2) and link(1) and finally with link(3). this demonstrated the heavily congested conditions. also figure (18) prove the above statement interms of estimating the delay per travelling kilometer for each segment length (1.03, 0.520, and 0.620) km for link (1, 2 and 3) respectively studied in this research. figure (17) depicted the maximum value for delay per km that obtained for link(1) which is about 266 sec/km and 268 sec./km for (3) and 244 sec/km for link (2). fig. 17. travel time index results for link (1), (2) and (3). zainab ahmed al-kaissi al-khwarizmi engineering journal, vol. 13, no. 3, p.p. 120130 (2017) 129 fig. 18. average delay per kilometer results for link (1), (2) and (3). 5. conclusions it can be drawn the following points: 1. maximum travel time of 518.5 sec. and delay time of 457sec. which is about 88% of travel time for link (1); also 238sec. total travel time for link (2) with delay time of 206sec. which is about 86% loss of travel time. for link (3) a maximum travel time of 210 sec. and delay time of 172 sec. which is about 81.9% is lost due to delay congestion. 2. stopped delay compromise the major part of intersection delay for all links studied. also the acceleration time delay is higher than deceleration time due to the conflict vehicles in the intersection. 3. buffer time index results in worse reliability conditions. link (2) produced a buffer index of about 36% and 26 % for link (1) and finally for link (3) which presented a 24% buffer index. 4. the 95% percentile travel time of about (301.9, 219.4, and 193.8) sec. for link (1, 2 and 3) respectively. higher value for 95% travel time is obtained for link (1). 5. travel time index tti of 4.2 %, 4.9% and 4% is obtained for link (1, 2 and 3) respectively. higher travel time index for link (2) and link (1) and finally with link (3) respectively. 6. maximum value for delay per km that obtained for link(1) which is about 266 sec/km and 268 sec./km for (3) and 244 sec/km for link(2). 6. refrences [1] richardson a. j. and taylor, m.a.p. (1978):" travel time variability on commuter journeys". high speed ground transportation journal. 6. pp. 77–79. [2] rakha, h., el-shawarby, i., m. arafeh & dion, f. (2006):" estimating path traveltime reliability". proceedings of the ieee ‐itsc 2006. toronto, canada. september 17-20. [3] arezoumandi, m. (2011):"estimation of travel time reliability for freeways using mean and standard deviation of travel time". journal of transp. syst. engineering and info. tech. volume 11. issue 6. [4] pu, w. (2010): "analytic relationships between travel time reliability measures. compendium of papers trb". 90th annual meeting. washington, d.c., usa. [5] polus, a. (1979): "a study of travel time and reliability on arterial routes. transportation". 8. pp. 141–151. [6] al-deek, h. & emam, e.b. (2006): "new methodology for estimating reliability in transportation networks with degraded link capacities". journal of intelligent transportation systems. pp. 117–129. [7] taylor, m. & susilawati, s. (2012):" modeling travel time reliability with the burr distribution". procedia social and behavioral sciences. volume 54. 4 october 2012. pp. 75–83. [8] susilawati, s., taylor, m.a.p. & somenahalli, s.v.c. (2012):" distributions of travel time variability on urban roads". journal of advanced [9] federal highway administration. (2005):" traffic congestion and reliability: trends and advanced strategies for congestion mitigation". cambridge systematic inc. and texas transportation institute, college station, tx. [10] chen, c., skabardonis, a., and varaiya, p. (2003). “travel time reliability as a measure of service.” in transportation research record: journal of the transportation research board, 1855, pp. 74–79. )2017( 120-130، صفحة 3د، العد13دجلة الخوارزمي الهندسية المجلم زينب احمد القيسي 130 نة بغدادشارع فلسطين شرياني حضري في مديالتنبؤ لزمن الرحلة ومؤشرات الوثوقية ل نماذج زينب أحمد القيسي كلية الهندسة / الجامعة المستنصرية قسم هندسة الطرق والنقل / dr.zainabalkaissi77@uomustansiriyah.edu.iq:البريد االلكتروني الخالصة رحالت تخطيط النقل. الهدف للشبكة المرورية ولتوزيع أفضل لحساب زمن الرحلة وحسابات الوثوقية هي عوامل مهمة لتحسين كفاءة التشغيل واألمان واحد دد والذي يعمقاطع مختارة من شارع فلسطين الشرياني في مدينة بغدا ةمن الرحلة الكلي وتحليل التوزيع لزمن الرحلة لثالثزمن هذا البحث هو حساب لد ضغط إضافي من الشوارع المهمة التي تمر في المناطق السكنية والتجارية في مدينة بغداد نتيجة التطور السريع الحاصل في استعماالت األرض والذي يو لتوليد وجذب الرحالت اليومية. . ١من زمن الرحلة بسبب طبيعة زدحام المرور في المقطع رقم %٨٨ثانية حيث يتم ضياع ٤٥٧ثانية وزمن التأخير ٥١٨٫٥أعلى قيمة لزمن الرحلة . وبالنسبة للمقطع اً تأخيربوصفه %٨٦ثانية أي يتم ضياع من الوقت بحوالي ٢٠٦ثانية وزمن تأخير بحدود ٢٣٨, ٢وزمن الرحلة المستغرق للمقطع رقم تم الحصول عليه ٣٨, ٥٩, ٦٢ bufferبالوقت بسبب تأخير الزدحام. زمن ضياع %٨١٫٩ثانية ويمثل حوالي ١٧٢أعلى زمن رحلة مستغرق هو ٣رقم ً على التوالي. هذا يعني وقت ١٬٢٬٣بالنسبة للمقطع رقم ً إضافي ا على التوالي من معدل زمن الرحلة للحصول ١٫٢٫٣لكل من المقطع ٥٩٬٣٨.,٦٢بحدود ا من باب المعظم إلي ٢أظهرت سوء الوثوقية. المقطع رقم bufferللوصول غاية الرحلة في نهاية الطريق الشرياني. نتائج مؤشرات زمن %٩٥على دقة مؤشر وثوقية $٢٤من تقاطع الموال إلى تقاطع باب المعظم وأخيرا ١قية بالنسبة لمقطع رقم مؤشر وثو %٢٦مؤشر وثوقية و %٣٦تقاطع الصخرة أعطى , ٣٠١على التوالي. زمن تأخير إضافي بحدود ١٬٢٬٣من تقاطع الصخرة إلى تقاطع ساحة بيروت. هذه النتائج تدل على سوء مؤشرات الوثوقية لمقطع رقم تم الحصول من النتائج على .١زمن الرحلة للمقطع رقم %٩٥على التوالي. تم الحصول على أعلى قيمة ل ١٬٢٬٣ثانية للمقطع رقم ١٩٣٫٨, ٢١٩٫٤ يدل على استغراق وقت إضافي ١٫٠على التوالي. زيادة مؤشر زمن الرحلة اكبر من ١٬٢٬٣للمقطع رقم %٤, و ٤٫٩, ٤٫٢مؤشر زمن الرحلة حوالي . اعلى قيمة لنتائج ٣وأخيرا للمقطع رقم ٢رقم و مقطع رقم ١اطع الثالثة المدروسة مع اعلى مؤشر زمن رحلة للمقطع للرحلة عن الوقت الحر المثالي للمق نماذجأيضا تم تطوير . ٢ثانية /كلم للمقطع رقم ٢٤٤و ٣كلم /ثانية للمقطع رقم ٢٦٨ثانية /كلم و ٢٦٦بحوالي ١التأخير لكل كم طول كانت للمقطع رقم مقارنة لزمن الرحلة للمقاطع الثالثة في منطقة الدراسة لشارع فلسطين اعتمادا على البيانات الحقلية المستحصلة. تم الحصول على توافق جيد عندالتنبؤ للبيانات الحقلية. النماذجمع البيانات الحقلية لزمن الرحلة مما يبين قابلية تمثيل ا النماذج al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 6, no. 3, pp 61-76 (2010) the effect of surface roughness on thermohydrodynamic performance in misaligned journal bearings basim ajeel abass mustafa mohammed k. department of mechanical engineering/ college of engineering/ university of babylon (received 19 july 2009; accepted 7 september 2010) abstract in this work an approach has been developed to investigate the influence of surface roughness on thermohydrodynamic performance in aligned and misaligned journal bearings by considering an average flow model and deriving the shear flow factor for various roughness configurations, similar to the pressure flow factor. an average reynolds equation for rough surfaces is defined in term of pressure and shear flow factors, which can be obtained by numerical flow simulation, though the use of measured or numerically generated rough surfaces. reynolds, heat conduction and energy equations are solved simultaneously by using a suitable numerical technique (finite difference method) to obtain the pressure and temperature distribution through the oil film thickness of the journal bearing. these equations are obtained for isotropic surfaces and for surfaces with directional patterns. the flow factors for these surfaces are expressed as empirical relations in term of normalized oil film thickness (h/σ) and surface characteristic (γ) defined as the ratio of x and z correlation lengths . the results of this approach showed increase in load carrying capacity and maximum pressure and decrease in maximum temperature in the case of stationary surface roughness (rough bearing and smooth journal) with transverse pattern. the results obtained through this work have been compared with that published by other works and found to be in a good agreement. keywords: thermohydrodynamic performance, surface roughness, misalignment, journal bearing 1. introduction the study of surface roughness effects in micro machine design has intensively been the subject of investigations in recent years. over the past several years, the incorporation of many physical effects into the analysis of fluid-film bearings has provided much more realistic performance data. in particular , the familiar assumptions of a smooth surface , isothermal operating condition , aligned journal bearing and newtonian behavior of the lubricant can no longer be employed to accurately predict the performance of fluid-film bearing system, as in [1, 2, 3, 4, 5] to study a thermohydrodynamic (thd) performance in aligned journal bearings. oscar pinkus [6] and safar [7] studied the analysis of misaligned grooved journal bearings and energy loss from misalignment state. buckholz [8] and jiin-yah jang [9] investigated the effect of misalignment on load for thermal and adiabatic condition by using non-newtonian lubricant. moreover, to improve the performance of journal bearings, a surface finish that can enhance the performance under their geometric and operating conditions has to be sought. hence studies that deal with the influence of surface roughness on performance of journal bearing systems are more appropriate. in recent years, a considerable amount of research activities have been devoted to the study of surface roughness effects on the performance of hydrodynamic journal bearing systems. the influence of surface roughness in most of these studies has been included using either stochastic model (limited to two specific types of roughness structures; one dimensional ridges oriented either transversely or longitudinally ) or average flow model proposed by nadir patir and h.s.cheng [10, 11] .zhang et.al [12] presented a transient (thd) analysis of mixed lubrication. the reynolds equation has been modified for onethis page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ basim ajeel abass al-khwarizmi engineering journal, vol. 6, no. 3, pp 61 76 (2010) ٦٢ dimensional transverse , isotropic and longitudinal roughness patterns , and then extended this work for the case of a non-newtonian lubricant obeying power law model for dynamic load . these studies have been limited to the effect of onedimensional surface roughness on the performance of hydrodynamic journal bearings. the limiting cases of roughness found in real engineering surfaces and hence, many investigators used the modified form of patir and cheng average flow model to include the combined influence of more realistic threedimensional (3d) surface roughness and thermal behavior of lubricant on the performance of hydrodynamic journal bearings. nagaraju et.al [13] investigated the influence of surface roughness on newtonian and non-newtonian lubricant in hybrid journal bearing by solving the average reynolds equation, heat conduction and energy equations simultaneously using numerical method and showed the thermal effect for each moving and stationary surface roughness. kim and kim [14] showed the effect of surface roughness on thd analysis with film condition and predicting the bearing parameters such as pressure and temperature distribution in lubricating films between the stationary and moving surfaces. fanghui shi et.al [15] studied a mixed – tehd model for journal bearing conformal contacts by using a thermal process for temperature analysis and a thermal –elastic process for deformation calculations. ramish et.al. [16] studied the thd analysis of submerged oil journal bearings considering surface roughness effect. a parametric study of steady state behavior has been carried out .a numerical study deals with the improvement of the thd performance of a 100mm plain journal bearing subjected to a constant misalignment torque under steady state conditions found by bouyer and fillon [17]. thermohydrodynamic analysis of surface roughness in the flow field has been carried out by joon and joo [18]. the pressure and temperature distribution in the lubricating film of a lemon-bore journal bearing has been studied by ron et.al. [19]. in the present work , application of mathematical model (average flow model) and a general solution scheme are presented to include the combined effect of surface roughness and misalignment of journal axes on the performance of the journal bearing lubricated with newtonian lubricant. the average reynolds equation, heat conduction and energy equations are simultaneously solved through a suitable numerical technique for transverse, isotropic and longitudinal surface patterns orientation. 2. governing equations and bearing geometry a schematic diagram for the journal bearing used in the present analysis with the suitable coordinates has been shown in fig (1). it can be shown in this figure the effect of surface roughness of both journal bearing surfaces on the oil film thickness. the following equations are used to solve the problem of the present work. a. coordinate system b. bearing misalignment c. film thickness function fig.1. geometrical configuration of rough misaligned journal bearing. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ basim ajeel abass al-khwarizmi engineering journal, vol. 6, no. 3, pp 61 76 (2010) ٦٣ 3. average reynolds equation for the laminar flow of an incompressible, newtonian lubricant and for thermal condition in the clearance space between rough surfaces of journal and bearing, the modified average reynolds equation for misaligned journal bearing in non-dimensional form can be written as in [13, 15, 20]:    st zx ghg p fh l rp fh                                        1 3 2 3 …(1) where   4 1 0 4321     dy f   4 1 0 2     yd g and yd y  1 0 1  , yd y  0 2 1  , yd y y  0 3  , yd 1 0 4 1  the empirical relations of pressure flow factors ( yx  , ) are expressed as in patir and cheng [11]  hr x ce  1 for 1   r x hc   1 for γ > 1 …(2a) and            1 ,, hh xz …(2b) where c and r are the constants that can be found in table (1) or as expressed in [10]. and γ is the surface pattern parameter. the shear flow factor ( s ) in journal bearing system is expressed as [11]   ss vrj  12 …(3a) фs is a positive function of h/σ and the surface pattern parameter of a given surface.      2321 1 hh s eh   for 5h  h s e  25.0 2 for h > 5 …(3b) b1, b2, α1, α2 and α3 are constants and can be obtained from patir and cheng [11] or table (2). table 1, coefficients of pressure flow factors γ c r range 1/6 1.38 0.42 h>1 1 0.9 0.56 h>0.5 6 0.52 1.5 h>0.5 table 2, coefficients of shear flow factors γ b1 α1 α2 α3 b2 1/6 1.962 1.08 0.77 0.03 1.754 1 1.899 0.98 0.92 0.05 1.126 6 1.290 0.62 1.09 0.08 0.388 4. oil film thickness the local oil film thickness ht is defined as 21   hht …(4) where (h) is the nominal oil film thickness (compliance) defined as the distance between the mean levels of the two surfaces . δ1 and δ2 are the random roughness amplitudes of the two surfaces measured from their mean levels . δ1 and δ2 are assumed to have a gaussian distribution of heights with zero mean and standard deviations σ1 and σ2 respectively . the combined roughness δ=δ1+δ2 has a variance 2 2 2 1   . the ratio h/σ is an important parameter showing the effect of surface roughness. for h/σ > 3, fully lubrication occur in journal bearing system, the roughness become important as h/σ→3. as h/σ decrease under 3 asperities start interacting with each other and contact form. the directional properties of roughness are described by a surface pattern parameter γ, it defined as the ratio of x and y correlation lengths: z x 5.0 5.0    …(5) this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ basim ajeel abass al-khwarizmi engineering journal, vol. 6, no. 3, pp 61 76 (2010) ٦٤ γ can be interpreted as the length to width ratio a representative asperity , purely transverse , isotropic and purely longitudinal roughness structures correspond to γ = 0,1,∞, respectively . for the journal bearing system having gaussian distribution of surface heights the expression for average fluid – film thickness ( th ) in fully lubricated ( 3h ) and partially lubricated ( h <3) regions in misaligned journal bearings is expressed as below. hht  for 3h   2 2 2 1 2 1 2 h t e h erf h h                  for h < 3 …(6) where h is the nominal fluid-film thickness (the fluid-film thickness of smooth journal bearing system) and is introduced as: ● in alignment journal bearing system  cos1 h …(7a) ● in misalignment journal bearing system    sincoscos1 21  h …(7b) where 11 tan2              d l c r …(7c) 22 tan2              d l c r …(7d) where γ1 , γ2 are the tilting angles in vertical and horizontal direction of bearing as in [8, 9] 5. heat-conduction equation the temperature distribution through the sold bush can be evaluated by solving the heatconduction equation. the steady state heatconduction equation with no heat source in nondimensional form can be written as [2]: 0 11 2 2 22 2           t rr t rr t …(8) 6. energy equation when the misaligned journal bearing operated in a fully lubricated condition, the heat generated due to asperity contact can be neglected and only the heat generated due to viscous shear of the lubricant is considered. the non-dimensional form of energy equation with the assumption that the lubricant density and thermal conductivity remains constant is shown in [2, 6]:                                                        22 232 2 22 11 1 .. y w y u hy t h y t z h h y w l rh h y u h vt u tt t t t tt      …(9) where : oil o k urc  1 , 2 2       c r and inoil in tk u c r 22 3         7. fluid-film velocity components the flow of lubricant between two rough surfaces can be modeled by an equivalent flow model. the equivalent flow model is defined as two smooth surfaces separated by a clearance equal to the average gap ( th ). based on the equivalence of flow though the average fluid-film thickness and though the local fluid-film thickness, a group of new pressure flow factors ( yx   , ) and a shear flow factor ( s  ) can be evaluated as follows: x t x h h  3 3  ; y t y h h  3 3  and ss   …(10) the velocity components in circumferential and axial direction in non-dimensional form are expressed as [13]: this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ basim ajeel abass al-khwarizmi engineering journal, vol. 6, no. 3, pp 61 76 (2010) ٦٥                             1 0 0 1 0 0 0 1 0 1 0 02 1 1 1 1 1 1 . yd yd h yd yd yd ydyd y yd yp hu y t s y y y tx         4 2 4 2 4 21 3 2                    t s tx h p hu    …(11)                          y y tz yd ydyd y yd y l r z p hw 0 1 0 1 0 02 1 1 .                     4 21 3 2 l r z p hw tz …(12) where wu , are the velocity components in circumferential and axial directions respectively. the fluid-film velocity component across the fluid-film is obtained from the continuity equation and is expressed in non-dimensional form as: yd y uh h y z w l ru hv y t t t                        0 .  …(13) 8. viscosity equation the viscosity of the lubricant was assumed to be variable across the film and a round the circumference. the variation of viscosity with the temperature is given by the following equation as described by [2]: 2 21 tktkko  …(14) where 1,kko and 2k are constant given in table (3) or as expressed in [2,4,5] table 3, geometric and operation parameters of the bearing bearing length l = 0.08 m external bearing radius rbout = 0.1 m journal radius r = 0.05 m radial clearance c = 0.000152 m eccentricity ratio ε = 0.62 surface roughness parameter λ = 10 surface pattern parameter for transverse, isotropic and longitudinal roughness pattern γ = 1/6 , 1 , 6 respectively inlet lubricant temperature tin = 40 c° ambient temperature ta = 40 c° inlet pressure pin = 70000 pa rotation speed s = 2000 rpm lubricant density ρ = 860 kg/m3 lubricant specific heat co = 2000 j/kg.c bush convection heat transfer hc = 80 w/m2.c bush thermal conductivity kb = 250 w/m .c lubricant thermal conductivity koil = 0.13 w/m . c tilt angles in vertical and horizontal direction γ1. γ2 = 0.0002, 0.00005 rad viscosity coefficient  21,, kkko 3.287, 3.064, 0.777 respectively **(the symbols (gm) and (s) in all figures below refer to surface roughness pattern γ and rotational speed of journal u respectively ) . 9. boundary conditions to analyze the thermohydrodynamic performance in rough and misaligned journal bearing system, the following boundary conditions can be used. ● lubricant flow field 1. at the journal bearing edges 0z and 1z → 0.0 atmpp 2. at the cavitations zone 0.0    p and 0.0p (reynolds boundary conditions) this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ basim ajeel abass al-khwarizmi engineering journal, vol. 6, no. 3, pp 61 76 (2010) ٦٦ ● thermal field 1. the temperature across the oil film in the grove zone known as mixed temperature (tmix) is assumed to be constant and can be estimated as described by [2, 16]: inrec ininrrec mix qq tqtq t    …(15a) where rt recirculation temperature int inlet oil temperature inq supply oil flow rate m3/sec recq recirculation flow rate (m3/sec) and is expressed as follow : ydhulucq trec  1 0 …(15b) 2. the heat flux continuity on the surface between the bush and the oil film interface which yields to the following boundary condition as described by [2, 13]: 01 . 1 ..       yt bin b oil r y t hc r k k r t …(16a) where bin b r r r  3. the boundary condition which referred to the heat loses by free convection [2]:  abobin b conv rr ttr k h r t bout     …(16b) 10. solution procedure thermohydrodynamic analysis of a rough misaligned journal bearing system required the simultaneous solution of governing equations with appropriate boundary conditions described above. these equations are numerically solved using a finite difference method, with appropriate iterative scheme. the solution procedure is as follows: 1. input the operatng conditions, characteristic properties, initial pressure and temperature distributions of oil film. compute initial value of attitude angle ( ) as:   2 1 1 4 tan    …(17) compute the nominal, average film thickness and pressure, shear flow factors from equations (2, 3, 6, 7). 2. evaluate the viscosity distribution and the values of (a1, a2, a3, a4) 3. new pressure distribution can be obtained by an iterative scheme with successive under relaxation method which was employed to solve the average reynolds equation .the iterations stops if convergence criterion (error) reaches (10-4). new value of attitude angle ( ) is calculated as follows:         rw wt1tan …(18) where rw and tw are the radial and the tangential components of the load which can be expressed as:   1 0 2 0 ..cos   zddpwr   1 0 2 0 ..sin   zddpwt the old and new attitude angle are compared. if the difference between angles is less than one degree then calculate velocity component using eqs (11, 12, 13). 4. calculate the mixing temperature from equation (15) and leakage flow rate as follows:     2 0 1 01 dydhwrucq t … (19) 5. the heat transfer equation (8) and energy equation (9) with the boundary conditions are solved simultaneously. a direct iterative procedure with successive under relaxation has been adopted to get the temperature field through the oil film. the new oil-film temperature is used to compute a new viscosity field in step (2) which is subsequently used to solve the average reynolds equation and simultaneous solutions for the equations are obtained iteratively until the converging criteria of the temperature for all points on the boundary between the oil film and the inner bush face is less than (10-6). a computer program written in fortran-90 has this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ basim ajeel abass al-khwarizmi engineering journal, vol. 6, no. 3, pp 61 76 (2010) ٦٧ been prepared to solve the governing equations of the problem. an average execution time of five minutes has been found suitable to execute the program. figure (a-1) shows the program flow chart. 11. results and discussion the results obtained through this work have been computed for the geometric and operating parameters of the bearing presented in table (3). the results obtained in the present work for smooth aligned journal bearing are compared to the experimental results obtained by j.ferron et al [2] as shown in figures 2, 3, 4, 5 and 6 , the maximum error for load carrying capacity is 3.5%, for maximum pressure 5% and for maximum temperature 3% . it seems from these figures that the results are in a good agreement. the above comparison represents a good verification to the computer program prepared to solve the problem of this work. fig.2. temperature distribution with circumferential location in aligned smooth journal bearing. fig.3. pressure distribution vs. circumferential location in aligned smooth journal bearing. fig.4. load with eccentricity ratio in aligned smooth journal bearing. fig.5. maximum pressure vs. eccentricity ratio in aligned smooth journal bearing. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ basim ajeel abass al-khwarizmi engineering journal, vol. 6, no. 3, pp 61 76 (2010) ٦٨ fig.6. maximum temperature vs. eccentricity ratio in aligned smooth journal bearing. figures (7, 8) show the influence of surface roughness orientation γ and surface roughness characteristics of opposing surfaces (ie. variance ratio vrj) on fluid-film temperature distribution (t) along the circumferential direction at an axial midplane ( 5.0 ) and across the midfilm ( 5.0y ) in misaligned journal bearing. the moving roughness (rough journal and smooth bearing vrj=1.0) provides increasing in circumferential fluid-film temperature distribution as compared to that obtained in smooth journal bearing, this is because the moving roughness have positive shear flow factor s which increases the fluid-film velocity in the circumferential direction and consequently the viscous shear of lubricant , hence the fluid-film temperature increased . on the other hand the stationary roughness (rough bearing and smooth journal vrj=0.0) reduces the fluid-film velocity in the circumferential direction (since s is negative) causes a reduced fluid-film temperature. the transverse roughness pattern (γ=1/6) having a larger value of shear flow factor , provides maximum reduction and maximum increasing in the values of circumferential fluid-film temperature distribution in stationary and moving roughness cases respectively . fig.7. temperature distribution vs. circumferential location for moving roughness in misalignment journal bearing. fig.8. temperature distribution vs. circumferential location for stationary roughness in misalignment journal bearing. the influence of surface roughness on circumferential fluid-film pressure distribution at an axial midplane ( 5.0 ) in misaligned journal bearing with stationary and moving surface roughness can be shown in figure (9), it can be deduced from this figure that the stationary roughness (vrj=0.0) and transverse pattern (γ=1/6) combination increase the pressure as compared with smooth bearing. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ basim ajeel abass al-khwarizmi engineering journal, vol. 6, no. 3, pp 61 76 (2010) ٦٩ fig.9. pressure distribution vs. circumferential location for moving and stationary roughness in misalignment journal bearing. figures (10, 11) show the effect of surface roughness on load carrying capacity with increase eccentricity ratio in aligned and misaligned journal bearing for moving and stationary roughness. in case of the moving surface roughness in misaligned bearing the load carrying capacity increases with eccentricity ratio (in transverse and isotropic surface pattern). it is also clear that the load carrying capacity for the bearing with transverse and isotropic surface roughness is less than that in smooth journal bearing. this is because the shear flow factor in moving roughness is positive and this causes a decreased pressure and then the load of the bearing. in longitudinal pattern the increase with the eccentricity ratio is more than that in smooth bearing. in case of the stationary roughness the increase of the load with eccentricity ratio is more than that in smooth bearing this is because the negative shear flow factor. it can also be shown from these figures that the increase in load carrying capacity with the eccentricity ratio in case of moving and stationary roughness in aligned journal bearing is always higher than that obtained from misaligned journal bearing. fig.10. load vs. eccentricity ratio for moving roughness in alignment and misalignment journal bearing. fig.11. load vs. eccentricity ratio for stationary roughness in alignment and misalignment journal bearing. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ basim ajeel abass al-khwarizmi engineering journal, vol. 6, no. 3, pp 61 76 (2010) ٧٠ fig.12. maximum pressure vs. eccentricity ratio for moving roughness in alignment and misalignment journal bearing. fig.13. maximum pressure vs. eccentricity ratio for stationary roughness in alignment and misalignment journal bearing. figures (12, 13) show an increase of maximum pressure value with respect to eccentricity ratio under the effect of moving and stationary surface roughness for aligned and misaligned journal bearing . the increase of maximum pressure with the eccentricity ratio is less than that in smooth journal bearing for the moving roughness except of the longitudinal pattern (γ=6). it can also deduced from figure (13) that the maximum pressure of the oil is always higher for stationary surface roughness (vrj = 0.0). this is attributed to the negative shear flow factor in this case, which causes higher viscosity and hence higher pressure. these figures also show that the maximum pressure decreases when the misalignment of the journal center has been considered. the decrease in maximum pressure has been calculated and found to be 48% for the bearing with moving roughness while it becomes 31% for the bearing with stationary roughness. the maximum oil film temperature increases with increasing eccentricity ratio as shown in figures (14, 15). it is clear that the maximum temperature becomes higher when the moving surface roughness is considered. it can also be deduced from these figures that the maximum temperature for stationary roughness is lower than that obtained from smooth journal bearing. in alignment state the maximum temperature value is higher than that in misalignment bearing. this is due to the effect of reduction in pressure field. figures (16, 17) show the effect of surface roughness on attitude angle in aligned and misaligned journal bearing. the attitude angle decreases with the increase of eccentricity ratio. the reduction of attitude angle with eccentricity ratio is less than that in smooth journal bearing for the case of moving surface roughness. this can be attributed to the reduction of the load in this case. in stationary roughness this reduction become more than that in smooth bearing because of the increasing in load. figures (18, 19) show that the side leakage flow rate increases with the eccentricity ratio for smooth, moving and stationary roughness in alignment and misalignment cases. fig (18) shows that the oil side leakage flow rate is decreased when the moving surface roughness effect is considered. this is attributed to the positive shear flow factor s which increased the mean recirculation flow rate. the mean recirculation flow rate is decreased and side leakage flow rate increased in the case of the bearing with stationary this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ basim ajeel abass al-khwarizmi engineering journal, vol. 6, no. 3, pp 61 76 (2010) ٧١ roughness as shown in fig (19), which is attributed to the negative shear flow factor s in this case. fig.14. maximum temperature vs. eccentricity ratio for moving roughness in alignment and misalignment journal bearing. fig.15. maximum temperature vs. eccentricity ratio for stationary roughness in alignment and misalignment journal bearing. fig.16. attitude angle vs. eccentricity ratio for moving roughness in alignment and misalignment journal bearing. fig.17. attitude angle vs. eccentricity ratio for stationary roughness in alignment and misalignment journal bearing. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ basim ajeel abass al-khwarizmi engineering journal, vol. 6, no. 3, pp 61 76 (2010) ٧٢ fig.18. side leakage flow rate vs. eccentricity ratio for moving roughness in alignment and misalignment. fig.19. side leakage flow rate with eccentricity ratio for stationary roughness in alignment and misalignment. 12. conclusions the results presented in this study lead to the following conclusions: 1. the surface roughness characteristics of opposing surfaces (i.e.., variance ratio, vrj) and roughness orientation (γ) play an important role in reducing or increasing fluidfilm temperature. the stationary roughness with a transverse roughness pattern provides maximum reduction in fluid-film temperature. 2. misalignment with surface roughness in journal bearing leads to decrease each of load, pressure and temperature as compared with the aligned journal bearing. 3. the loss in load-carrying capacity due to thermal effects can be partially retrieved from a suitable surface roughness combination. the stationary roughness (i.e., rough bearing and smooth journal) and transverse roughness pattern (γ=1/6) is suitable nomenclature c = radial clearance (m) co = specific heat of lubricant j/kg. ºc d = diameter of journal bearing (m) gf , non-dimensional integration functions of viscosity h = nominal film thickness (m) h non-dimensional nominal film thickness, chh  ht = local film thickness in rough surfaces (m) th average film thickness in rough surfaces convh convection heat transfer coefficient w/m2. ºc 2,1,0k viscosity coefficients koil = thermal conductivity of the lubricant w/m. ºc kb= thermal conductivity of the bush w/m. ºc l = journal bearing length (m) p non-dimensional pressure : 2cur p p in  recq recirculation flow m3/sec this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ basim ajeel abass al-khwarizmi engineering journal, vol. 6, no. 3, pp 61 76 (2010) ٧٣ inq inlet flow in the bearing groove m3/sec 1q side leakage flow rate m3/sec r = radius of journal (m) t non-dimensional fluid – film temperature int = inlet fluid temperature in the bearing groove ºc tmix = mixed temperature in a groove at non-dimensional ambient temperature ºc u = journal rotational speed (rpm) or (s in all figures) wvu ,, non-dimensional components of the fluid velocity in the x, y and z direction, ,uuu  cuvrv  , uww  vrj , vrb = variance ratio of journal and bearing, ((σ1, σ2)/σ)2 w non-dimensional applied load :  2crul w w in  x, y, z = coordinate in circumferential , across film and axial direction respectively and in dimensional form zy,, non-dimensional coordinates, lzzhyyrx  ,, δ1, δ2 = random roughness amplitudes (m) σ1, σ2 = standard deviations λ0.5x ,λ0.5z= auto correlation lengths in x and z direction respectively yx  , pressure flow factors s shear flow factor λ = surface roughness parameter, c  21 , two independent misalignment parameters 21, tilt angles  non-dimensional lubricant viscosity ρ = lubricant density (kg/m3) in inlet fluid viscosity in the bearing groove pa.s  attitude angle 13. references [1] b. c. majumar, 1974, "the thermo hydrodynamic solution of oil journal bearings", wear, vol. 31, pp. 287 – 294. [2] j. ferron, j. frene and r. boncompain, 1983, "a study of the thermohdrodynamic performance of a plain journal bearing comparison between theory and experimental", asme j. lubr. technol., vol. 105, pp. 422 – 428. [3] junichi mitsui, yukio hori and masato tanaka, 1986, "an experimental investigation on the temperature distribution in circular journal bearings", asme j. tribol., vol. 108, pp. 621 – 626. [4] jun'ichi mitsui, 1987, "a study of thermo hydrodynamic lubrication in a circular journal bearing", tribol. international, vol. 11, pp. 331 – 341. [5] h. h. oh and g. paradissiadis, 1988, "them hydrodynamic analysis of journal bearings considering cavitation and reverse flow", asme j. tribol., vol. 110, pp. 439 – 447. [6] oscar pinkus and s. s. bupara, 1978, "analysis of misaligned grooved journal bearings", asme j. lubr. technol., vol. 101, pp. 503 – 508. [7] z. s. safar, 1984, "energy loss due to misalignment of journal bearings", tribol. international, vol. 03, pp. 107 – 110. [8] r. h. buckholz and j. f. lin, 1986, "the effect of journal bearing misalignment on load and cavitation for non-newtonian lubricants", asme j. tribol., vol. 108, pp. 645 – 653. [9] jiin-yuh jang and chongching chang, 1987, "adiabatic solutions for a misaligned journal bearing with non-newtonian lubricants", tribol. international, vol. 09, pp. 267 – 275. [10] nadir patir and h. s. cheng, 1978, "an average flow model for determining effects of three-dimensional roughness on partial hydrodynamic lubrication", asme j. lubr. technol., vol. 100, pp. 12 – 17. [11] nadir patir and h. s. cheng, 1979, "application of average flow model to lubrication between rough sliding surfaces" asme j. lubr. technol., vol. 101, pp. 220 – 230. [12] chao zhang and h. s. cheng, 2000, "transient non-newtonian thermohydrodynamic mixed lubrication of dynamically loaded journal bearings", trans. asme, vol. 122, pp. 156 – 161. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ basim ajeel abass al-khwarizmi engineering journal, vol. 6, no. 3, pp 61 76 (2010) ٧٤ [13] t. nagaraju , satish c. sharma and s. c. jain, 2007, "influence of surface roughness on non-newtonian thermohydrostatic performance of a hole-entry hybrid journal bearing" asme j. tribol., vol. 129, pp. 595 – 602. [14] j. h. kim, s. k. kim and j.-h. kim, 2004, "the influence of surface roughness on thermohydrodynamic analysis", kookmin university [15] fanghui shi and qian (jane) wang, 1998, "a mixed – tehd model for journal – bearing conformal contacts – part i: model formulation and approximation of heat transfer considering asperity contact", asme j. tribol., vol. 120, pp. 198 – 205. [16] j. ramesh, b.c. majumdar and n.s.rao, 1997, "thermohydrodynamic analysis of submerged oil journal bearings considering surface roughness effects", transactions of the asme, vol.119, january, pp. 100-106. [17] j. bouyer and m. fillon, 2003, "improvement of the thd performance of a misaligned plain journal is bearing", transactions of the asme, vol.125, pp.334-342. [18] joon hyun kim and joo-hyun kim, 2005, "thermohydrodynamic analysis of surface roughness in the flow field", journal of tribology, vol. 127, pp. 293-301. [19] ron a.j. van ostayen and anton van beek, 2009, "thermal modeling of the lemon-bore hydrodynamic bearing", tribology international , vol 42,pp.23-32. [20] yansong wang, chao zhang, q. jane wang and chih lin, 2002, "amixed – tehd analysis and experiment of journal bearing under severe operating conditions", tribol. international, vol. 35, pp. 395 – 407. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ basim ajeel abass al-khwarizmi engineering journal, vol. 6, no. 3, pp 61 76 (2010) ٧٥ appendix ( a ) program flowchart calculate new pressure distribution ),1,( kip for the oil film matrix using the solution of equation (1) start input data jboil convoinoin ainboutbin vrkk hcpkkk ttnclrrr ,,,,,,, ,,,,,, ,,,,,,,, 21 21    generate mesh calculate  from equation (17) calculate the nominal, average film thickness and pressure, shear flow factors in all grid points in the  z, plane from equations (2, 3, 6 and 7) assume the pressure and temperature in the oil film and temperature of bearing bush grid points calculate the viscosity field  ji , and the values of  gf , in the ),( y plane from equation (14) if error < 10-4 using under relaxation technique calculate the components of the load carrying capacity ),( tr ww and then new attitude angle  from equation (18) no yes 1 2 if 1 1  nn  calculate mixrec tqq ,, 1 from equations (15) and (19) calculate temperature distribution ),( jit for the oil film matrix by solving equation (9) simultaneously with equation (8) to get ),( jibt for bush if error < 10-6 calculate bearing performance parameters (total load, maximum pressure, maximum temperature, attitude angle and side flow rate) and then convert these values to the dimensional form write maxmax1),1,(),( ,,,,,, tpqwpt kiji  end yes no 1 2 no 1 calculate from equations (11),(12) and (13) this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ )2010( 76 -61 ، صفحة3، العدد 6مجلة الخوارزمي الھندسیة المجلد باسم عجیل عباس ٧٦ تأثیر خشونة السطح على االداء الحراري للمساند المقعدیة منحرفة المحاور كاظم باسم عجیل عباس مصطفى محمد جامعة بابل/ كلیة الھندسة/ سم ھندسة المیكانیكق الخالصة وذ ا البحث اعتماد طریقة لدراسة تأثیر خشونة السطح للمساند المقعدیة منحرفة المحور على االداتم في ھذ ذ نم ك بأخ اند ودل دل ء الحراري لتلك المس ج مع غطیة الجریان بنظر االعتبار واشتقاق معادالت الجریان القصیة لوضعیات ان الض امالت الجری ل لمع كل مماث طح وبش ونة الس ة لخش ة . مختلف اد معادل م اعتم ت طوح ذ جة ایمكن الحصول علیھا عن طریق النمذ رینولدز التي تتضمن معامالت الجریان القصیة والضغطیة والتي تخدام الس ان واس ة للجری ونة لعددی ات الخش ددیا دھا ع ن تولی ي یمك ك الت ة وتل ل ا . المقاس م ح رارة ت ال الح ة أنتق ة ،معادل ة الطاق ة رینولدز،معادل من معادل ي تتض وع والت ة للموض ادالت الحاكم لمع ة من لتوصیل،ومعادلة اللزوجة التي تأخذبا ة عددی تخدام طریق ا باس رارة، انی ات الح بة بنظر االعتبار اعتماد اللزوجة على درج ددة (اس ات المح ة الفروق ) طریق دي لك للحصول على توزیعات الوذ ند المقع ت للمس ة الزی الل طبق رارة خ ات الح و .ضغط ودرج م الحص طوح ذ ت ادالت لس ى المع ي ل عل ة ف ونة متماثل ات خش ذ . یةات مواصفات اتجاھجاھات واخرى ذجمیع االت ان لھ امالت الجری اد مع م ایج امالت ت ة المع ة بدالل ات تجریبی طوح كعالق رف و (h/σ) ه الس ي تع والت اض لة خالل ھذأظھرت النتائج المستحص). x,y(ل بأتجاھي بانھا نسبة عالقة الطو م وانخف غط االعظ ة الض ادة قیم ا العمل زیادة في تحمل المسند لالحمال وزی ى ال رارة االقص طوح ذ في قیمة درجة الح ة الس ي حال ت ف ا الزی ي یبلغھ ة ت ونة الثابت ي ) stationary surface roughness(ات الخش اند الت ي المس ي تعن والت .یكون فیھا السطح الداخلي للمسند خشنا وسطح المحور ناعما this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ 50-58 al-khwarizmi engineering journal,vol. 12, no. effect of magnesium addition on corrosion resistance of aluminum muna khethier *department of production engineering and metallurgy/ university of technology ** mechanical department / ***al (received http://dx.doi.org/10.22153/kej.2016.05.003 abstract the electrochemical behavior of alof the different wt% magnesium metal of 1wt%, the microstructures of prepared alloys were examined by optical investigated by using potentiostat instrument under static potentials test and corrosion current was recorded to determine corrosion resistance of all prepared samples. it was found that the addition of mg corrosion resistance of al-17%si alloy in 3.5%nacl solution. than the others while the alloys contain other alloys. keywords: al-si alloys, magnesiumaddition 1. introduction in industry aluminum and silicon used largely in different life fields applications and these alloys are modif various additives, before 50 years ago the scientific known this alloy having increasing in strength hypereutectic when increasing the si content and having decreasing in strength hypereutectic when decreasing the si conten hypereutectic al18%si it’s widely used product the light weight pieces such as (connecting rods, pistons, air conditioner, compressors, cylinder liners and engine cover this alloy having a good mechanical properties like wear and corrosion but it’s has a low thermal expansion and reduce density [2] khwarizmi engineering journal,vol. 12, no. 4, p.p. 5058(2016) effect of magnesium addition on corrosion resistance of aluminum -17%silicon alloy khethier abbass* khairia salman hassan kayser aziz ameen*** *department of production engineering and metallurgy/ university of technology ** mechanical department / institute of technologybaghdad ***al -esra’a university collegebaghdad *email:mukeab2014@yahoo.com **email:almaden20002000@yahoo.com ***email:kayseraziz@yahoo.com (received 15 september 2015; accepted 9 may 2016) http://dx.doi.org/10.22153/kej.2016.05.003 -17%si alloy is investigated in 3.5wt% nacl solution. many alloys with addition of the different wt% magnesium metal of 1wt%, 2%, 3wt% ,4.5wt% ,and 9wt% were prepared of prepared alloys were examined by optical and sem microscopes investigated by using potentiostat instrument under static potentials test and corrosion current was recorded to corrosion resistance of all prepared samples. it was found that the addition of mg si alloy in 3.5%nacl solution. the alloy containing 1%mg shows less corrosion rate containing 4.5%mg, 9%mg content have the better pitting addition ,corrosion behavior, microstructure. aluminum and silicon alloys are and industrial are modified by before 50 years ago the scientific known this alloy having increasing in strength hypereutectic when increasing the si content and having decreasing in strength hypereutectic when decreasing the si content.[1]. 18%si it’s widely used to product the light weight pieces such as (connecting rods, pistons, air conditioner, compressors, cylinder liners and engine cover), this alloy having a good mechanical properties t it’s has a low thermal although when added the small amount of (cu, ni and mg) these elements lead to increasing the casting properties’ improvement of the work hardening characteristics, good corrosion resistance and weldability this element reduce the thermal expansion coefficient and lead to poorm it is found that the coarser structures having high corrosion resistance than finer structures. silicon is contained another impo effect on the mechanical and corrosion resistances [5]. corrosion was the interaction between the metal surface and the wet media where the metal atoms dissolve as ions. to control the corrosion must prevent the contact between the a media and the metal surface and this can be obtained by interactive between the oxygen and the surface metal formed oxide film al-khwarizmi engineering journal (2016) effect of magnesium addition on corrosion resistance of khairia salman hassan** *department of production engineering and metallurgy/ university of technology 17%si alloy is investigated in 3.5wt% nacl solution. many alloys with addition nd 9wt% were prepared by gravity die casting . s. corrosion behavior was investigated by using potentiostat instrument under static potentials test and corrosion current was recorded to corrosion resistance of all prepared samples. it was found that the addition of mg metal improves the the alloy containing 1%mg shows less corrosion rate pitting corrosion resistance than although when added the small amount of ) these elements lead to increasing the casting properties’ improvement of the work hardening characteristics, good corrosion weldability, but when added the si, this element reduce the thermal expansion poormachinability [3,4]. found that the coarser structures having high corrosion resistance than finer structures. silicon another important parameter which effect on the mechanical and corrosion resistances corrosion was the interaction between the metal surface and the wet media where the metal to control the corrosion must prevent the contact between the aqueous media and the metal surface and this can be obtained by interactive between the oxygen and the surface metal formed oxide film, this film muna khethier abbass al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 5058(2016) 51 prevent any interaction . then the aluminum can be consider the metal which formed this film rapidly[6]. many studies were performed on this item nikanorovet al.[ 7] [2005]studied the microstructure and behavior of aluminum alloys which content silicon between (11.5 wt% 35 wt%)using rapid cooling of melts of various compositions alloys . theyfound that properties are depend on solidification factors during cooling of the alloys and it limited the yield values by elasto-plastic of microstructure of the silicon crystals and silicon grain boundaries. hamilta de oliveira santosa[8], studied the corrosion resistance performance of (alsi – cu) alloy in a solution condensate from automotive fuel combustion, which selected four alloy three of them were commercial alloys , all this alloys put in this solution . the results shown the differences in corrosion resistance and the fourth alloy have corrosion resistance higher than the commercial alloys. wislei r. osório et al.[ [9][2009], studied the effect of add some parameter to the aluminum such as (9% silicon) on the mechanical and the electro-chemical behavior of as cast and laser remeltedand observed that the fine silicon fibers have low effect on the electrochemical corrosion resistance and also observed the samples have high corrosion resistance as cast samples than laser remelted samples. rodríguez-diaz et al.[10] [2015], investigated the electro-chemical methods which consists of the potentiodynamic polarization curves, linear polarization resistance (lpr), electro-chemical impedance spectroscopy (eis) and electrochemical noise measurements (en).on the al mg – si alloy immersion in (3.5% nacl) solution as a function of time. they observed formed the mg2sicomplex compound and the formation of the galvanic couple (al-mg) which led to changed of the current density to maximum values. rodríguez-diaz et al. studied theeffect of the mg metal addition to al-17%si alloy with different percentages as follows:1.0%, 2.0%, 3.0% 4.5% and 9.0% and studied its effect on the corrosion resistance in 3.5%nacl solution 2. experimental work 2.1 materials used a liquid metallurgy route has been adopted to fabricate the cast al-17%siwith various addition of percentage of mg metal. the basealloy was melted in graphite crucible in furnace work by electric at 750ºcand then the preheated mg metal powder with size of 50µm was introduced into the alloy (al17%si) molten alloy with using vortex technique of the effectively degassed molten alloy,and then pouring the molten alloy in preheat cylindrical shape steel mold. the addition of the magnesium powder in the matrix alloy was by different percentages:1%,2%, 3% ,4.5% ,and 9.0%. table 1 shows the base alloy’s chemical composition . table 1, chemical composition of al-17%si alloy. element wt% si fe cu mg cr ni zn al 17 1.0 1.3 1.0 0.1 1.3 0.25 rem 2.2. fabrication of specimens the specimens was manufacturing with dimensions (1.5 x 1.5 x 0.2) cm for corrosion test according to astm ( g70-30 )the samples fabrication with increased the magnesium element in the alloy as shown in the table (2). table 2, classification of al-si alloy. specimen symbol state of specimen a base alloy without addition b base alloy with addition 1wt%mg c base alloy with addition 2wt%mg d base alloy with addition 3wt%mg e base alloy with addition 4.5wt%mg f alloy with addition 9.0wt%mg muna khethier abbass al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 5058(2016) 52 2.3 microstructure examination in order to examine the microstructuresof all prepared specimens groups, the specimens were prepared in sequence processes :the specimens were ground with using si cemery paper of grades :350,500,800 and 1000, and then they were polished with using special cloth and alumina al 2o3 solution of grain size 0.3 µm. etching process was carried out by immersion the specimen in etchant solution, keller’s reagent thatcontains of 95 ml distilled water, 2.5ml hno3, 1.5 ml hcl and 1 ml hf then washed the specimen with water and alcohol then dried by air. optical testes of specimens was done by optical microscope (ep-typ2) provided with computer and digital camera . 2.4 electrochemical corrosion test a specimen of an exposed area (1 x 1 cm2)ismounted with holder. theelectrode’s reference ismounted with (1 mm) away from the surface of the specimen. the electrode’s reference used in this workis saturated calomel electrode (sce). the electrode’s auxiliary used in the electro-chemical cell is platinum type. the holder of specimen , together with the reference and auxiliary electrode areputted in the respective positions in the electro-chemical cell used for this aim, as shown in figure 1. a current reading of cell is taken for a short, slow drag of the potential. the drag was taken from (–200 to +200) mv relative to (ocp ) . in this range the relation between the current density and voltage is almost nearly linear. a data for linear fitting of the standard model is givenas an estimation of the polarization resistance, that calculated the corrosion current density (icorr) and corrosion rate (mpy). the investigation are achievedusing a wenking mlab multi channels and sci-mlab corrosion measuring system from bank electronicsintelligent controls gmbh, germany 2007. when used all the samples in 3.5% nacl solution with ph of 6.8 to calculate the corrosion parameters, (corrosion potential (ecorr) and corrosion current ( icorr)), by tafel extrapolation method. then after calculate the (ecorr) and (icorr) these lead to calculate the corrosion rate as shown in equation (1).[11] fig. 1. the electrochemical cell unit used in this work. 3. results & discussions 3.1 microstructure results in the figure (2a) shows the microstructure of hypereutectic al–17 si alloys. it was revealed the presence of primary silicon in cuboids shape and eutectic silicon in needle shape and larger size phases . figure (2b) shows that the silicon interact with magnesium which lead to complex compound (mg2si). it gives the alloy higherhardness and strength values .this is because of precipitation of a new precipitate or 2nd phase particles due to period and heat from supersaturated solid solution. the results lead to when the aluminum is pure, it don’t generated dendrite. but when magnesium, silicon and other materials are added to pure aluminum the dendrite will growth through the microstructure as shown in figures(2c&2d). the feature of the dendrites are fine, have shape edge like needle (the dendrite are symmetry to the sandarac tree paper), growth freely into the structure of the metal liquid and the dendrite are largely at the neighboring aluminum grains. after some time the alloy becomes more solidification and more growth in dendrite the growing aluminum grain by a snow plow is represented infigures(2e&2f). figure 3shows sem micrographs of al-17%si alloy and with addition of mg. it was seen that silicon needle with various size and orientation muna khethier abbass al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 5058(2016) 53 and this phase is distributed of solid solution (α and eutectic phase ( figure 3a) while theaddition of mg lead to change of microstructure, it was observed grain refinement of αdendrites and silicon flakes in addition to distributed of mg2si particles in aluminum matrix as shown in figure (3 b &3c). fig. 2. shows the microstructures of hypereutectic aluminum and 17% silicon al–17 si alloys of specimens (a,b,c,d, e&f ) at magnification 400x. fig. 3. sem micrographs of base alloy al-17%si specimen and with addition of mg (a) base alloy al-17%si , (b) base alloy +1%mg , (c) base alloy +4.5%mg. a muna khethier abbass al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 5058(2016) 54 3.2. electrochemical corrosion results figure (4) al-si alloys samples(a,b,c,d,e&f) after corrosion test in the solution have 3.5% nacl or sea water .these figures shows the regions of cathodic and anodic, where the reduction of oxygen and dissolution of aluminum can take place respectively. corrosion parameters measured by tafel extrapolation of potentiodynamic curves. the curves above show the regions of anodic and cathodicwhich indicate that, the specimen (a) has an increase in corrosion current density (icorr) then corrosion rate increases. when magnesium is add to al-17%si at different percentages, it was we seen improvement in corrosion rate for all specimens . this is due to the change in microstructure after casting due to refinement in eutectic (al+si) and silicon phase and also forming mg2si particles in specimens (b)which act as cathodic and al matrix as anode . while the specimens c,e&f give convergent in result due to coarser dendritic structuresinter dendritic mixture’s eutectic.these results are in agreement with those of researcher wislei r. osórioet al.[12], they studied theeffect of silicon content on microstructure and electrochemical behavior of hypoeutectic al–si alloys ,they concluded that the increased on silicon content had provided a dendritic refinement and a more extensive redistribution of the eutectic mixture which has result the decreased on the resistance’s corrosion. based on the electrochemical reactions of aluminum and its alloys in a natural chloride containing environment, the following anodic reaction for anodic polarization of aluminum is proposed: al + 3h2o → al(oh)3+ 3h++ 3e …(2) the formation of the pit leads to the dissolution of aluminum, which causes the migration of chloride ions into the pit and the formation of aluminum chloride inside the pit, according to the following reaction: al → al+3+ 3e …(3) al +3+ 3cl→ alcl3 …(4) conversely, the following electrochemical reaction is proposed for the cathodic polarization of aluminum: o2+ 2h2o + 4e →4oh … (5) 2h2o + 2e→2oh-+ h2 …(6) in the present work the addition of mg metal to al-17%si alloy lead to formationthe complex phase (magnesium hydroxide) which product the alloy from corrosion. these results are getting by researcher song et al. 1997[13]who show the complex compound mg(oh)2 are product the aluminum alloy from corrosion behavior according following reactions: 2h++2e-h2 (cathodic partial reaction) …(7) 2mg 2mg+ +2e (anodic partial reaction) …(8) 2mg+ +2h2o 2mg2+ +2oh+h2 …(9) 2mg+ +2h+ +2h2o 2mg2+ +2oh+2h2 ( overall reaction) … (10) mg2+ +2oh mg(oh)2 ( corrosion product formation) …(11) equations 7 and 8, represent cathodic and anodic reactions whichtaken place more than on a surface coated using the film that the chemical reaction in eq.9 represents the chemical oxidation of mg+ to mg2+. the displayed of the overall reaction in eq.10andfinally, eq.11was the responsible for the forming of mg(oh)2 corrosion product. muna khethier abbass al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 5058(2016) 55 -3.00 -2.00 -1.00 0.00 1.00 current density [ma/cm2] -800.00 -700.00 -600.00 -500.00 p ot en tia l [ m v ] -3.00 -2.00 -1.00 0.00 1.00 current density [ma/cm2] -900.00 -800.00 -700.00 -600.00 -500.00 p ot en tia l [ m v ] -4.00 -3.00 -2.00 -1.00 0.00 current density [ma/cm2] -800.00 -750.00 -700.00 -650.00 -600.00 -550.00 p ot en tia l [ m v ] -5.00 -4.00 -3.00 -2.00 -1.00 current density [ma/cm2] -680.00 -640.00 -600.00 -560.00 -520.00 -480.00 p ot en tia l [ m v ] fig. 4. polarization curves of the al-si alloy for specimens (a,b, c,d,e&f) table 2, the results of corrosion tests of studied samples of al-si alloy in 3.5 % nacl solution. symbol mg %content i [µa/cm2] e (mv) i corr [��/cm2] a base alloy 24.3 -614.4 10.449 b 1wt%mg 2.8 -561.7 1.204 c 2wt%mg 8.7 -656.5 3.741 d 3wt%mg 9.4 -646.5 4.042 e 4.5wt%mg 7.7 -587.8 3.311 f 9.0 wt%mg 7.3 -597.4 3.139 specimena specimen b specimen c specimend specimen e specimen f muna khethier abbass al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 5058(2016) 56 3.3. micrographs after corrosion figure 5 shows the micrographs of all specimensafter putting all samples in solution have 3.5% nacl and the electrochemical corrosion is done. it was shown ( specimen a) contains number of large pits while the specimens containing different amount of mg have less number of small ( specimens b, c&d) and the pits become shallow pits as mg % increases or pits may be disappear as shown in specimens e&f. figure 5b gives the lowest value of corrosion rate due the effect of mg in forming finer dendritic structures.it was observed that the pit morphology on the al-17%si alloys showed hemispherical isolated deeper pits on the specimen a , while specimen c revealed a higher number of shallow pits. these results are in agreement with those results of hosni ezuberet al.[14]. fig. 5. micrographs after corrosion test in 3.5%nacl solution. 4. conclusions 1. it was found that mg addition has been effect of an effective modification of eutectic morphology on surface corrosion behavior of al–17%si alloy. 2. the increase in mg content in al-17%si has provided a dendritic refinement of αsolid solution and silicon needle phase 3. the addition of mg lead to more extensive distribution of the mg2si in aluminum matrix which has improved the corrosion resistance. 4. the al-17%si alloy containing 1%mg shows the better corrosion resistance or less corrosion rate than other alloys. 5. when added the mg toaluminum and 17% silicon improved the pitting corrosion resistance in 3.5% nacl solution but the alloys containing 4.5%mg, 9%mg content show the better pitting corrosion resistance than other alloys. 5. references [1] s.p. nikanorova” structural and mechanical properties of al–si alloys obtained by fast cooling of a levitated melt” materials science and engineering,vol. a 390 (2005) pp.63–69 [2] naglaa fathy1” microstructural evolution of hyper-eutectic al-18% si alloy during semi-solid isothermal heat treatment int journal of research in chemical, metallurgical and civil engg. (ijrcmce) vol. 1, issue 1(2014) issn 2349-1442. [3] hemantkumarneopaney” study of mechanical and tribological properties of al-si alloy prepared by powder metallurgical technology “journal of mechanical and civil engineering, vol.11, issue 5 ver. iii (sepoct. 2014), pp. 54-63 [4] r. s. rana, rajesh purohit, and s das, “reviews on the influences of alloying elements on the microstructure and mechanical properties of aluminum alloys and aluminum alloys composites”. international journal of scientific and muna khethier abbass al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 5058(2016) 57 research publications, vol. 2, issue 6, june 2012 [5] articles “corrosion of aluminum and aluminum alloys" knowledge articles from www. keyto –metals .com in international 2005. [6] w.b. wan nik, o. sulaiman, “corrosion behavior of aluminum alloy in seawater”, the international conference on marine technology, 11-12 december 2010, buet, dhaka, bangladesh 175. [7] s.p. nikanorov, m.p. volkov, v.n. gurin, yu.a. burenkov, l.i. derkachenko, b.k. kardashev, l.l. regel, w.r. wilcox, ,” structural and mechanical properties of al– si alloys obtainedby fast cooling of a levitated melt” materials science and engineering , vol.a 390 (2005), pp. 63–69. [8] hamilta de oliveira santosa “corrosion performance of al-si-cu hypereutectic alloys in a synthetic condensed automotive solution”, materials research, vol. 8, no. 2, (2005), pp. 155-159. [9] wislei r. osório *, noé cheung, leandro c. peixoto and amauri garcia **o , “corrosion resistance and mechanical properties of an al 9wt%si alloy treated by laser surface remelting” ,int. j. electrochem. sci., vol.4 (2009) ,pp.820 – 831. [10] r. a. rodríguez-diaz, j. uruchurtu-chavarín, a. m. cotero-villegas, s. valdez, j. a. juárez-islas ,”corrosion behavior of almgsi alloy in aqueous saline solution” int. j. electrochem. sci., vol.10 (2015),pp.1792– 1808. www.electrochemsci.org [11] annual book of astmstandards, “standard practice for calculation of corrosion rates and related information “, g102-89,vol. 03.02, 2004. [12] wislei r. osório, pedro r. goulart, amauri garcia, “effect of silicon content on microstructure and electrochemical behavior of hypoeutectic al–si alloys”, materials lettersvol. 62, issue 3, 15 february (2008), pp. 365–369. [13] g. song, a. atrens, d. stjohn, x. wu, j. nairn, corrosion science, vol.39 (1997) pp.1981-2004. [14] hosni ezuber, ,a. el-houd, f. el-shawesh, “ a study on the corrosion behavior of aluminum alloys in seawater”, materials & design ,vol. 29, issue 4, 2008, pp. 801–805, 2nd international conference on advances in production and processing of aluminum. ���س��� �� � �� 4، ا���د��12 � ا���ارز�� ا����� � ا���� ،2016( 58-50( 58 %١٧سيليكون –لسبيكة المينيوم التآكل االمغنيسيوم على مقاومة ضافة أتأثير ��ن #"! *��� �� ���س� �% �** ! ) �'%' أ�)*** ��� ا� ��������/ ��� ھ���� ا�� �ج وا����دن* �� ا� **� #"�اد ا���!� ا� ������� ا� ��/ ��� ا������� ***�$%& ���/ ��� ھ���� ا� ���' وا��� *(�� ا��%اء ا� mukeab2014@yahoo.com :ا��� %و�� ا�&%$� * almaden20002000@yahoo.com :ا��� %و�� ا�&%$�** kayseraziz@yahoo.com :ا��� %و�� ا�&%$�*** الخالصة �2(�ل ) al17%si(ا�&12 �0 درا�� ا��(�ك ا��!%و*����وي ��&��� ,� ھ+ا �,)3.5 wt% nacl( ����ن ا��"�����م �(�&�4 �,�6�# �، وذ� �9) :�ا�>�4� �� �0 ا� ���ل ا���!% و.����ذ#��##�ا�?� ��ا�; ا�<; ا��&�4� =�1wt%, 2wt%, 3wt%, 4.5wt%, 9wt% ( %�<20 �0 1(و#��; 4�ا���!%ي %*�; �a29 ا�وا���!% ا��� %و�� ا����@ �&�)� . وpotentiostat ( g20(ا���!�د ا���*e* f #�ا�?� ا� ���ل �!�ز cو�0 #12 ا�(�ب ا� &�ر ا��!� ا���*f و�0 �0��e ��0ر ا� e*i و=��ب � �و�� ا� e�� e*i ا����ذج ا��2>%ةjن ا��"��و. ا���� �و�� ا� m=�� �� e*i ا���k l ا�6,� f� �$n$ م��� �4�&� �,)al-17%si ( ل�)2� �,)3.5% nacl(. o)k �$ا��2و �0���ل ا�e اظ!%ت ) mg %1(و��=m ا$>�ً ان ا��&�4c ��f ا��&�4 e* ����# ى%jا� �� ) mg, 4.5% mg %9( ا��2و$� g��*o)k ا��&�4) �0��� �و e<,ا � �*e ا�� %ي �f #��� ا��&�4)�. بشرى وليث al-khwarizmi engineering journal,vol. 12, no. performance assessment bushra s. albusoda *,**department of civil engineering (received abstract an evaluation for the performance of model pile embedded in expansive soil was investigated program was planned to achieve the purpose of this research. therefore, special manufactured system was prepared for studying the behavior of model pile having different length to diameter ratios (l/d). two types of piles were used in this research, straight shaft and under reamed piles. the effect of model pile type, l/d ratio and number of wetting drying cycles were studied. it is observed that significant reductions in pile movement when under reamed piles were considered. a proposed design charts was presented for straight shaft and under reamed piles to estimate the length of both types of piles that is required to exert minimized uplift pressure when the soil swells. keywords: expansive soil, pile model, reamed piles 1. introduction although expansive soils are considered one of the problematic soils in the world and especially in iraq, it represents serious problem when exist under the foundations, due to the volume change that exhibit when changes in moisture content were occurred. this behavior causes exte damages to structures erected on these soils. in iraq, expansive soils are found at northern and middle parts of the country, with different swelling tendencies foundations on expansive soils pose a unique challenge to the geotechnical engineer. they usually cost more than construction of foundations on ordinary soils as well as the site investigation and the foundation design (nelson et al., 2012). one of the important issues is to insure the stability of the structure constructed on expans soil, a conventional solution is to use piles as a foundation for the structure so it can reach a relatively stable zone in the deep layers of the soils especially when the swelling potential of the underneath expansive soil is so high that conventional soil treatment is considered not effective or not even economical. the using of piles as a practical foundation system in expansive khwarizmi engineering journal,vol. 12, no. 2, p.p. 19 (2016) performance assessment of pile embedded in expansive soil albusoda* laith a. al-anbary civil engineering/ college of engineering/ university of baghdad email: albusoda@yahoo.com (received 26 april 2015; accepted 26 november 2015) an evaluation for the performance of model pile embedded in expansive soil was investigated program was planned to achieve the purpose of this research. therefore, special manufactured system was prepared for studying the behavior of model pile having different length to diameter ratios (l/d). two types of piles were used in this research, straight shaft and under reamed piles. the effect of model pile type, l/d ratio and number of wetting drying cycles were studied. it is observed that significant reductions in pile movement when under reamed piles were sed design charts was presented for straight shaft and under reamed piles to estimate the length of both types of piles that is required to exert minimized uplift pressure when the soil swells. reamed piles, wetting drying cycles, pile movement. are considered one of the problematic soils in the world and especially in iraq, it represents serious problem when exist under the foundations, due to the volume change that exhibit when changes in moisture content were occurred. this behavior causes extensive damages to structures erected on these soils. in iraq, expansive soils are found at northern and middle parts of the country, with different foundations on expansive soils pose a unique challenge to the geotechnical usually cost more than construction of foundations on ordinary soils as well as the site investigation and the foundation one of the important issues is to insure the stability of the structure constructed on expansive soil, a conventional solution is to use piles as a foundation for the structure so it can reach a relatively stable zone in the deep layers of the soils especially when the swelling potential of the underneath expansive soil is so high that l soil treatment is considered not effective or not even economical. the using of piles as a practical foundation system in expansive soils has been recommended in practice by many researchers such as (chen, 1975 and arora, 2008). many researchers experimental, theoretical and field studies for the past five decades on piles embedded in expansive soils to make a better understanding of the behavior of the pile in such soil conditions. it was concluded from the literature that an inves of the piles’ movement and uplift force due to soil swelling when subjecting the surrounding soil to wetting-drying cycles for representing seasonal moisture content changes is needed to support the scientific and practical research. therefore, an extensive testing program was planned to investigate each of the following: • straight shaft and under reamed piles movement when subjecting the surrounding soil to wetting-drying cycles in order to represent seasonal moisture content changes. • exerted uplift force from straight shaft and under reamed piles due to soil swelling for different wetting-drying cycles. • comparison between the pullout capacity of straight shaft and under reamed piles for non swelling and swelling soil conditions al-khwarizmi engineering journal (2016) n expansive soil anbary** university of baghdad an evaluation for the performance of model pile embedded in expansive soil was investigated. an extensive testing program was planned to achieve the purpose of this research. therefore, special manufactured system was prepared for studying the behavior of model pile having different length to diameter ratios (l/d). two types of piles were used in this research, straight shaft and under reamed piles. the effect of model pile type, l/d ratio and number of wetting drying cycles were studied. it is observed that significant reductions in pile movement when under reamed piles were sed design charts was presented for straight shaft and under reamed piles to estimate the length of soils has been recommended in practice by many researchers such as (chen, 1975 and arora, 2008). many researchers have conducted experimental, theoretical and field studies for the past five decades on piles embedded in expansive soils to make a better understanding of the behavior of the pile in such soil conditions. it was concluded from the literature that an investigation of the piles’ movement and uplift force due to soil swelling when subjecting the surrounding soil to drying cycles for representing seasonal moisture content changes is needed to support the scientific and practical research. fore, an extensive testing program was planned to investigate each of the following: straight shaft and under reamed piles movement when subjecting the surrounding drying cycles in order to represent seasonal moisture content changes. ed uplift force from straight shaft and under reamed piles due to soil swelling for drying cycles. comparison between the pullout capacity of straight shaft and under reamed piles for nonswelling and swelling soil conditions. bushra s. albusoda al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 19(2016) 2 2. material properties 2.1. expansive soil the expansive soil used in this research was artificially prepared by mixing iraqi bentonite from al-anbar city / bushayrah valley, about 35 kilometers southern al-waleed military base from a depth of three and a half meters from natural ground level, with karbala sand. in order to increase the permeability of the prepared soil and to facilitate and accelerate saturation process, several trial mixes of bentonite-sand were performed. a ratio of expansive soil to sand of (9/1) was selected. at this ratio, the soil remains highly expansive and its permeability is increased. 2.2. model piles 2.2.1. straight shaft piles nine straight shaft piles have been formed using solid aluminum rod with a diameter of 10mm and three different pile embedment lengths of 100mm, 150mm and 200mm that give l/d ratios of 10, 15 and 20 respectively. the dimensions are shown in fig. 1 which illustrates that there is an extension of 20 mm in length of all piles for fixing and measurement. fig. 1. dimensions of model straight shaft 2.2.2. under-reamed piles nine under reamed piles with single bulb at the bottom of the pile were made using a solid aluminum rod with 200mm diameter and then formed to give the shape of an under reamed pile as shown in fig. 2 with dimensions recommended by (pumina, 2005) of stem diameter of 10mm, bulb diameter of 200mm and a bucket length of 10mm, the l/d ratios were 10, 15 and 20. there is an extension of 20 mm in length of all piles for fixing and measurement. the surface of the model piles has been textured to insure the interlock between the pile and the surrounding soil. fig. 2. dimensions of model reamed pile 2.2.3. soil container twenty five soil steel containers were made using a 4mm thickness steel plate with the dimensions of (25cm × 25cm ×35cm). the sides of the containers were perforated with 25 holes each with 3mm diameter to decrease soil saturation period, the containers were painted with two coats of anti-rust paint and then two layers of gray base paint to resist the corrosion during test period. fig. 3 shows the dimensions of the soil container bushra s. albusoda fig. 3. soil container dimensions 2.2.4. manufactured apparatuses the main goal of this research is to investigate the effect of wetting and drying cycles on the movement and uplift force of piles embedded in expansive soil which will consume too much time to cover different l/d ratios and types of model piles, for that reason, manufacturing of special devices and apparatuses was needed to shorten test period as will be discussed in details in the following sections. 2.2.5. saturation-drying model for pile upward movement the basic idea here is to manufacture a saturation-drying model for the soil containers; that is large enough to contain eight containers at one time, and to be the same model that the drying process would take place in, instead of transferring the soil containers to a suitable oven. for that purpose, a large tank was made of galvanized steel plate of 2mm thickness and dimensions of (150cm x 80cm x 40cm). a was then attached to the side of the model to use it when conducting drying process. in addition, a drainage valve was then fixed at the bottom of the model. fig. 4 illustrates the dimensions and the shape of the saturation model. fig. 4. the saturation-drying model al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 3 soil container dimensions. manufactured apparatuses the main goal of this research is to investigate the effect of wetting and drying cycles on the uplift force of piles embedded in expansive soil which will consume too much time to cover different l/d ratios and types of model piles, for that reason, manufacturing of special devices and apparatuses was needed to shorten ed in details in the drying model for pile the basic idea here is to manufacture a drying model for the soil containers; that is large enough to contain eight containers at to be the same model that the drying process would take place in, instead of transferring the soil containers to a suitable oven. for that purpose, a large tank was made of galvanized steel plate of 2mm thickness and dimensions of (150cm x 80cm x 40cm). a flange was then attached to the side of the model to use it when conducting drying process. in addition, a drainage valve was then fixed at the bottom of the model. fig. 4 illustrates the dimensions and the drying model a cap for saturation-drying model was also made using galvanized steel plate of 2mm thickness and dimensions of (160cm x 80cm x 40cm). this cap is used only when drying process is performed. for the purpose of soil drying, many researchers used electrical heaters around the soil; the defect here is that the heaters provide heat only for the vicinity area around the heaters which will cause a large gradient in the temperature between the core and the outside of the soil (especially for large soil samples). to overcome this defect, a specially designed heating source was manufactured using three rows of electrical heaters each with 7 kw capacity and a fan, all assembled in a thermally isolated aluminum box to give what is called a hea fig. 5, also a thermometer was provided to the heating duct to control the temperature of soil drying which was fixed to 50 system for heating (drying process) can be in fig. 6. fig. 5. heating duct details fig. 6. heating system for drying process khwarizmi engineering journal, vol. 12, no. 2, p.p. 19(2016) drying model was also made using galvanized steel plate of 2mm thickness and dimensions of (160cm x 80cm x 40cm). this cap is used only when drying process for the purpose of soil drying, many searchers used electrical heaters around the soil; the defect here is that the heaters provide heat only for the vicinity area around the heaters which will cause a large gradient in the temperature between the core and the outside of the soil for large soil samples). to overcome this defect, a specially designed heating source was manufactured using three rows of electrical heaters each with 7 kw capacity and a fan, all assembled in a thermally isolated aluminum box to give what is called a heating duct as shown in fig. 5, also a thermometer was provided to the heating duct to control the temperature of soil drying which was fixed to 50o celsius. the whole system for heating (drying process) can be shown heating duct details. heating system for drying process. bushra s. albusoda 2.2.6. saturation-drying model for pile uplift force measurement another saturation-drying model was manufactured with the same dimensions for the purpose of measuring pile upward movement. this model is similar to that illustrated in previous section with one difference that this model was provided with a rectangular steel tube frame fixed above it to hold on the proving rings installed above the piles as shown in fig. 7. the rectangular steel frame was p adjustable screws for adjusting the distance between the proving rings and the piles. fig. 7. saturation-drying tank for pile uplift force measurement. fig. 8. details of pile pull-out loading frame 2.2.7. pile pull-out loading frame special pull-out loading frame was manufactured for measuring pile pull as illustrated in fig. 8. a load cell with its al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 4 drying model for pile uplift force measurement drying model was manufactured with the same dimensions for the purpose of measuring pile upward movement. similar to that illustrated in previous section with one difference that this model was provided with a rectangular steel tube frame fixed above it to hold on the proving rings installed above the piles as shown in fig. 7. the rectangular steel frame was provided with adjustable screws for adjusting the distance between the proving rings and the piles. drying tank for pile uplift out loading frame. out loading frame out loading frame was manufactured for measuring pile pull-out capacity . a load cell with its indicator was attached to measure the applied tension force on the pile, and two dial gauges were fixed above the pile cap holders to indicate the upward displacement of the pile due to applied force. 2.3. testing program the testing program consists mainly of two series. the first series include the physical properties tests. the second series comprises the pile model tests on both straight shaft and under reamed piles. the pile model tests consist of pile movement test due to wetting consumed 153 days (58 days for the first cycle, 49 days for the second cycle and 46 days for the third cycle) as shown in fig. 9. a fig. 9. schematic view for pile movement model test a:top view, b: sec a khwarizmi engineering journal, vol. 12, no. 2, p.p. 19(2016) indicator was attached to measure the applied tension force on the pile, and two dial gauges were fixed above the pile cap using two magnetic holders to indicate the upward displacement of the the testing program consists mainly of two series. the first series include the physical properties tests. the second series comprises the pile model tests on both straight shaft and under reamed piles. the pile model tests consist of pile e to wetting-drying cycles which consumed 153 days (58 days for the first cycle, 49 days for the second cycle and 46 days for the third b c fig. 9. schematic view for pile movement model test a:top view, b: sec a-a, c: sec b-b bushra s. albusoda the pile uplift force test through wetting drying(six pile models were tested on three wetting-drying cycles which consumed an average period of 45) as shown in fig. 10. a b c fig. 10. uplift force saturation-drying tank a: top view of the tank, b: section a c: section b-b the pull-out capacity test was performed according to astm d3689-07 (section 8.1.2 quick test procedure) on six model straight shaft piles, three of them were embedded in an expansive soil prepared at initial water content of al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 5 the pile uplift force test through wettingdrying(six pile models were tested on three drying cycles which consumed an average drying tank a: top view of the tank, b: section a-a, out capacity test was performed 07 (section 8.1.2 quick test procedure) on six model straight shaft piles, three of them were embedded in an expansive soil prepared at initial water content of 2% dry of optimum and the othe embedded in expansive soil at the same initial water content but exposed to wetting that consumes 40 days for each model. another six pile model tests were conducted on under reamed piles to determine the pull out capacity of these piles, three of them when the soil was wetted, and the other three model tests when the soil was prepared at initial water content without wetting, see fig. 11. it is important to note that each test is conducted on three different l/d ratios (10, 15, and 20). fig. 11. model pile pulltesting. 2.4. physical properties the following table gives the physical properties of the used expansive soil, (table 1). table 1, physical properties of expansive soil test standards soil classification uscs maximum dry density (mdd) astm d698 optimum moisture content (omc) specific gravity gs astm d854 liquid limit astm d4318 plastic limit plasticity index swelling pressure standard oedometer test khwarizmi engineering journal, vol. 12, no. 2, p.p. 19(2016) 2% dry of optimum and the other piles were embedded in expansive soil at the same initial water content but exposed to wetting that consumes 40 days for each model. another six pile model tests were conducted on under reamed piles to determine the pull out capacity of these e of them when the soil was wetted, and the other three model tests when the soil was prepared at initial water content without wetting, . it is important to note that each test is conducted on three different l/d ratios (10, 15, out test system during roperties tests the following table gives the physical properties of the used expansive soil, (table 1). physical properties of expansive soil. standards results uscs ch astm d698-12 1.23 g/cm3 34 % astm d854-10 2.52 astm d4318-10 102 % 45 % 57 standard oedometer test 312 kpa bushra s. albusoda al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 19(2016) 6 2.5. soil bed preparation the soil bed is prepared in the container to be ready for performing model tests. two trial mixes were carried out on sand mixing percentages of 5% and 10% with the soil. the two percentages of mixing reduced the swelling pressure of the soil and certainly increased the permeability. fig. 12 shows the variation of swelling pressure with the sand mixing percentages. fig. 12. relationship between sand-soil mixing percentage and the resulting swelling pressure y. the soil bed was prepared on a dry density of 1.225 g/cm3, which corresponds to a water content of 2% dry of optimum. the required amount of expansive soil was placed inside the container to one fifth of the final thickness of the bed of the soil and compacted using a hand hammer with a square base of the same internal dimensions of the soil container and a hole centered on its base in order not to let the pile be affected during soil compaction as shown in fig. 13. this method of compaction was performed by many researchers such as (al-ani, 1993, almaamoury, 1994 and chao, 2007). four sand drains were formed around the pile using thin walled steel tube (10 mm diameter and 250 mm length). the sand drains were spaced 100 mm from the pile (center to center). the sand used was passing sieve no.8 and prepared at a relative density equal to 82% to decrease soil saturation period. required amount of expansive soil is poured onto the soil container compaction of soil to the required level by using the specially manufactured hand hammer fig. 13. placing of expansive soi bed layers and compaction. 3. model test results 3.1. pile movement model test 3.1.1 experimental model test results the upward movement of the piles due to soil swelling and the downward movement due to soil shrinkage were recorded with time for straight shaft and under reamed piles with l/d ratios of 10, 15 and 20. fig. 14 illustrates the recorded results. 3.1.2. proposed design chart based on the experimental model test, a design chart is presented in fig. 15 to determine the required depth of the pile to resist the tension forces exerted by the swelling soil and produce zero or allowable upward movement. the concept of the following design chart is that the soil swelling decreases with deeper soil layers. this design chart provides values for unloaded piles so 200 250 300 350 400 450 0 5 10 s w e ll in g p re ss u re ( k p a ) sand mixing percentage (%) bushra s. albusoda in the case of loaded piles it will be in the safe conservative side. fig. 14. pile movement compared to soil surface movement due to wetting-drying cycles for straight shaft and under reamed piles. fig. 15. proposed relationship for determining required pile dimensions to resist upward movement due to soil swelling at the end of the first wetting-drying cycle 3.2. pile uplift pressure model test results 3.2.1. experimental model tests when the soil swelling is happened, the shear strength of the soil is reduced, maximum swelling occurs in the top layers of the soil which surrounds shallower piles , thus, the maximum loss in soil shear strength during swelling occurs in the top soil layers. therefore, shallower piles exerts less uplift forces due to soil swelling and more upward movement comparing to deeper al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 7 in the case of loaded piles it will be in the safe fig. 14. pile movement compared to soil surface drying cycles for straight fig. 15. proposed relationship for determining required pile dimensions to resist upward he end of the first pile uplift pressure model test results experimental model tests when the soil swelling is happened, the shear strength of the soil is reduced, maximum swelling occurs in the top layers of the soil which surrounds shallower piles , thus, the maximum loss in soil shear strength during swelling occurs rs. therefore, shallower piles exerts less uplift forces due to soil swelling and more upward movement comparing to deeper piles which are anchoraged in the relatively deeper soil layers that have less tendency to swelling. the magnitude of uplift resistan straight shaft and under reamed piles due to soil swelling in the first cycle is illustrated in fig. 16. fig. 16. effect of l/d ratio on straight shaft and under reamed piles uplift resistance by soil swelling 3.2.2. piles pull-out capacity model test the model test results for piles pull upward movement behavior was presented through table 2. for straight shaft and under reamed piles it was noticed that deeper piles with higher l/d ratios showed greater p comparing to the shallower piles for wetted and unwetted soil states. also, the under reamed piles showed more resistance to the applied uplift forces than the stra ight shaft piles because of the presence of the base bulb which provides e soil layers and thus more pull out force resistance for the under reamed piles. table 2, increment in pile pull-out capacity unwetted state l/d straight shaft piles under reamed 10 18.46 n 15 30.45 n 20 56.14 n wetted state l/d straight shaft piles under reamed 10 16.156 n 15 26.10 n 20 35.00 n khwarizmi engineering journal, vol. 12, no. 2, p.p. 19(2016) piles which are anchoraged in the relatively deeper soil layers that have less tendency to swelling. the magnitude of uplift resistance from straight shaft and under reamed piles due to soil swelling in the first cycle is illustrated in fig. 16. fig. 16. effect of l/d ratio on straight shaft and under reamed piles uplift resistance by soil swelling. out capacity model test the model test results for piles pull-out load upward movement behavior was presented through table 2. for straight shaft and under reamed piles it was noticed that deeper piles with higher l/d ratios showed greater pull out capacity comparing to the shallower piles for wetted and unwetted soil states. also, the under reamed piles showed more resistance to the applied uplift ight shaft piles because of the presence of the base bulb which provides extra anchorage in deep soil layers and thus more pull out force resistance for the under reamed piles. out capacity. under reamed piles increment ratio% 20.77 n 12.50 39.15 n 28.57 91.23 n 38.46 increment ratio% under reamed piles 18.46 n 14.26 34.80 n 33.33 63.00 n 80.00 bushra s. albusoda al-khwarizmi engineering journal, vol. 12, no. 2, p.p. 19(2016) 8 4. conclusion one of the challenges in geotechnical engineering is how to construct a stable foundation system to resist tension forces exerted by expansive soils and produce a safe building under this condition. the thought of this study was to examine the suitability of using under reamed with one base bulb as an alternative for straight shaft pile and study the behavior of both types of piles under seasonal moisture changes by applying successive cycles of wetting and drying to the soil that piles embedded in, the following points were concluded: 1pile upward movement due to soil swelling is reduced to about (20%-30%) when using under reamed pile with one base bulb instead of conventional straight shaft pile, deeper piles showed more resistance to upward and downward movement than shallower piles. 2a relationship is obtained for the piles upward movement that provides the required dimensions of any unloaded pile fully embedded in a very high expansive soil for zero upward movement or any recommended tolerable movements. for loaded piles, the results obtained from this relationship will be on the safe conservative side. 3pile uplift force due to soil swelling is reduced to about (10%-20%) when using under reamed piles instead of conventional straight shaft piles 4the use of under reamed piles instead of straight shaft piles for the same l/d ratio increases the pull out capacity of the piles by (12.5% -38.46%) for unwetted soil state, and about (14.26% 80%) for wetted soil state. notation d pile diameter ch fat clay l pile length 5. references [1] al-ani, r., 1993: “the behavior of model piles in expansive soils”, m.sc. thesis, university of technology, iraq. [2] al-maamoury, h. m., 1994: “the behavior of reinforced concrete model piles in expansive soil”, m.sc. thesis, university of technology, iraq. [3] arora k.r. 2008: “soil mechanics and foundation engineering 7th edition”, standard publishers distributers, delhi, india. [4] astm d 4318-00: “standard test method for liquid limit, plastic limit, and plasticity index of soils”. [5] astm d2435-96: “standard test method for one-dimensional consolidation properties of soils”. [6] astm d2487-00: “standard test method for classification of soils for engineering purposes (unified soil classification system)”. [7] astm d854-00: “standard test method for specific gravity of soil solids by pycnometer”. [8] astm d3689-07: “standard test methods for deep foundations under static tensile loads”. [9] chao, k. c., 2007: “design principles for foundations on expansive soils”, phd thesis, colorado state university, fort collins, usa. [10] nelson, j. d. , chao, k. c., overton, d. d., schaut, r. w., 2012: ”calculation of heave of deep pier foundation”, unsaturated soil: theory and practice, kasetsart university, thailand. [11] chen, f.h. 1975 “foundations on expansive soils, , elsevier scientific publication company. �� 2، ا���د����12 ا���ارز � ا���� �� ا���� ���ى ��� ز��ر �� ،9 -1 )2016( 9 ا*(��)�� %�ب &�%$��# اداء ر!� ة **�1ظ# ا/*,�ري-,� ا���+ * ���ى ��� ز��ر ����� ���اد /���� ا� ���� /��� ا� ���� ا������** ،* �و���� albusoda@yahoo.com : ا�!� � ا�� 2���ا� �و�� ����(ه ��'ذجا اداء ت#��� ت��� �* ��� +�ص �@�م ت<��= ت� �:�>.ا��را�� ھ:ه ھ�ف ��2#�7 �6 ا��3�45 ت� *12 �����0 +/ل �ا��,�+�� ت 4� ا�f ط'ل ���e اي �5��,� ��ط'ال ا����(ة ��'ذجا +'اص ��را��� �,��5�.-�g'� -� )h������دھ� ت� ا�gھ:ا *� ا ،i2!ا� )h������د � ا�gjا )h��� وا� � درا�� ت�.ا��'�= ذات�lmة،��!� �'ع ت)����ط�e دورات و�gد �4�ھ� ا�f ا����(ة ط'ل ا�� *� واtu �#<�ن �'حq.ا����h( ت<�ف f�g ا��o�,p ا� ����اح6 ت� ت<��� �345. ا��'�= ذات ا����h( ا���5ام g�� اf�g ا�f ا����(ة ح����د � �����h( ا�gjا )h��� ا����(ة ط'ل ����5ا��'�= ذات وا� �i�2� 0 ا���4'ب� 6�g wا� -�� �� -� 3�u د��xjا ��g خ�,���� ا�� .ا� <4d6963726f736f667420576f7264202d20cf20dae1ed20e6c7edcfe420e6ccc7ddedd120312d3130> al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 16, no. 3, sptember, (2020) p. p. 1-10 two-stage classification of breast tumor biomarkers for iraqi women iyden kamil mohammed* ali hussein al-timemy** javier escudero*** *,** department of biomedical engineering / alkhwarizmi college of engineering/ university of baghdad/ baghdad/ iraq *** school of engineering/ institute for digital communications/ the university of edinburgh/ alexander graham bell building/ eh9 3fg/ uk *email: aydenel_1969@yahoo.com **email: ali.altimemy@kecbu.uobaghdad.edu.iq ***email: javier.escudero@ed.ac.uk (received 18 november 2019; accepted 26 april 2020) https://doi.org/10.22153/kej.2020.04.003 abstract objective: breast cancer is regarded as a deadly disease in women causing lots of mortalities. early diagnosis of breast cancer with appropriate tumor biomarkers may facilitate early treatment of the disease, thus reducing the mortality rate. the purpose of the current study is to improve early diagnosis of breast by proposing a two-stage classification of breast tumor biomarkers fora sample of iraqi women. methods: in this study, a two-stage classification system is proposed and tested with four machine learning classifiers. in the first stage, breast features (demographic, blood and salivary-based attributes) are classified into normal or abnormal cases, while in the second stage the abnormal breast cases are further classified into either malignant or benign. the collected 20 breast cancer features are utilized to test the performance of the proposed classification system with leave-one-out (loo) cross validation and synthetic minority over-sampling technique (smote) to balance the classes. furthermore, correlation-based feature selection (cfs) was employed in an exploratory analysis to find the best features for the 2-stage classification system. results: classification accuracy of 9٤% for stage-1 and 100% for stage-2was achieved with a naïve bayesclassifier which outperformed other three methods. in addition, cfs selected small subset of features as being the best five features out of the all 20 features for both stage-1 and stage-2. conclusion: we achieved a high classification accuracy which is promising to help improve the early diagnosis of breast tumor. the outcome of this study also shows the importance of ca15-3protein in saliva and blood as well as carcinoembryonic antigen level and total protein in blood, and estrogen hormone level in saliva, for predicting breast tumors. keywords: breast cancer, correlation-based feature selection, decision tree, machine learning, oner algorithm, twostage classification. 1. introduction in iraq, breast cancer is regarded the most common type of malignancy [1], [2]. among all the malignant diseases, breast cancer is assessed as one of the main causes of death in postmenopausal women, accounting for 23% of all cancer deaths in 2017 [3]. in 2010, breast cancer is almost recognized as the deadliest cancer in women since it is regarded as number one cause of cancer mortality among women [4]. biomarkers have many potential applications in oncology, including screening, risk assessment, determination of prognosis, prediction of iyden kamil mohammed al-khwarizmi engineering journal, vol. 16, no. 3, p.p. 110 (2020) 2 response to treatment, differential diagnosis, and monitoring of progression of disease. due to the major role that biomarkers may play at all stages of disease, they should undergo rigorous evaluation, including clinical validation, analytical validation, and assessment of clinical utility prior to incorporation into regular clinical care [5]. a tumor biomarker is a molecular or processbased change that discloses the status of an underlying malignancy. a tumor biomarker may be diagnosed and assessed via one or more biomarker assays or tests. patient management is progressively being derived by tumor biomarker tests. this can be done by recognizing patients who do not require any, or recognizing other patients whose tumors are so unlikely to respond to a given type of treatment that it will drive to more harm than good. thus, patient management should be guided by a tumor biomarker test, to inspect if it has analytical validity, which means it is accurate, reliable and reproducible [6]. machine learning techniques have been utilized to classify cancer attributes and biomarkers aiming at improving the diagnosis rate. for instance, a classifierbased expert system was proposed in [7] for early diagnosis of prostate cancer with artificial neural network (ann) and support vector machines (svm). thirteen attributes were acquired from 300 men to classify benign and malignant tumors. classification accuracy of 79.3% and 80.1% was obtained with ann and polynomial svm, respectively. other researchers employed machine learning and data mining techniques to investigate breast tumors. three popular machine learning classifiers (naive bayes, radial basis function neural network (rbfnn), j48 decision tree) were used [8] to develop prediction models for 683 breast cancer cases. classification accuracy of 97.36%, 96.77 and 93.41% was obtained for the naive bayes, rbfnn, j48 classifiers, respectively. in another study, behadili et al. [9] analyzed 42 attributes of the iraqi women and selected 26 attributes for the classification of three classes with the decision tree j48 algorithm with 98% accuracy. other researchers tried to reduce the size of the feature set to detect breast cancer with independent component analysis (ica) [10]. a publicly available data set, wisconsin diagnostic breast cancer (wdbc) dataset, was utilized to test the proposed algorithm where the 30 attributes have been reduced to only one feature (ic). then, reduced feature was utilized to evaluate diagnostic accuracy with multiple classifiers: k-nearest neighbor (k-nn), ann, rbfnn, and svm. in some occasions, threeclass classification problems have been tackled such as the work in[11] by proposing two-stage classification where computer-aided diagnosis (cad) system have been proposed to classify brain tumors. the system classified brain tumor mri images into normal and abnormal images in the first stage and if the output was abnormal, then it was additionally classified into malignant or benign tumor. in this paper, we propose a two-stage classification for breast cancer classification with four machine learning classifiers. in the first stage, 20 breast attributes are classified into normal or abnormal cases whereas in the second stage the abnormal breast cases are further classified into malignant or benign. furthermore, correlation-based feature selection will be employed to find the best attributes out of the 20 attributes. the main contribution of this paper is that it presents a two-stage classification system for the classification of breast markers with machine learning classifiers. the most important attributes that are influential in the prediction of breast tumor will be investigated with correlation-based feature selection on a data set of 181 samples. 2. materials and methods a. details of breast cancer data collection the data set utilized in this study was acquired from the center for early breast cancer detection and elwiya oncology teaching hospital in 2013 and 2014. ethical approval to conduct the data collection was obtained from the ministry of health. in addition, data collection was performed in accordance with the declaration of helsinki 1964, and its later amendments. the data set consisted of 181subjects (111 malignant, 50 normal control and 20 benign cases). the oncologist examined subjects, with suspected breast tumor, and approved their inclusion in the study, confirmed with the following: 1) clinical examination, 2) breast biopsy, 3) mammogram and 4) ultrasound (us) scan. before the data collection, subjects were debriefed and consented to participate in the study. the data set has 20 attributes which can be categorized in 3 main categories, i) demographic information (9 attributes),ii) attributes derived iyden kamil mohammed al-khwarizmi engineering journal, vol. 16, no. 3, p.p. 110 (2020) 3 from blood samples (5 attributes) and iii) attributes derived from saliva (6 attributes). the nine demographic attributes include age, body mass index (bmi), total body fat index (tbf), waist hip ratio (whr), number of menstruation (mens.) cycles per year, duration of contraceptive intake per year, menstruation (mens.) cycle status (normal or abnormal), type of fucosyl transferase 2 (fut2) gene (secretor or non-secretor), type of lewis blood group. the 5biomarkers that are derived from blood samples included the level of estrogen hormone (es-b), the level of progesterone hormone (pgb), the level of ca15-3 protein (ca15-3 b), carcinoembryonic antigen level (cea-b) and total protein (tp-b). the biomarker that were obtained from analyzing salivary samples included the ph level (ph-s), salivary total protein (tp-s), estrogen hormone level (es-s), the level of ca15-3 protein (ca15-3 s), saliva progesterone hormone level (pg-s) and salivary carcinoembryonic antigen level (cea-s). b. details of the pattern classifcation in this study, a two-stage classification system is proposed where the breast attributes are classified into either normal or abnormal in the first stage. in the second stage of the classification, the abnormal instances can be further classified into malignant and benign cases. the general block diagram of the twostage classification system is shown in fig. 1. fig. 1. block diagram of the proposed breast attribute classification method. how to select the best machine learning classifier for the breast cancer detection can be considered as an open research question. therefore in this study we investigate the performance of the proposed two-stage classification system with four different classifiers: logistic regression [12], naïve bayes [13], decision tree [12] and oner [14]. the rationale behind choosing these machine learning classifiers to perform the analysis in this study was that these classifiers are relatively straightforward and simple to implement, and they have been utilised in the previous literature. weka, an open source software package [12] was used to perform classification with the four classifies in the current study. logistic regression is a traditional classification method where class probabilities are estimated by means of applying the logit transformation to a linear regression model [3]. it provides a mechanism for applying linear regression for performing classification [15]. for more details about the mathematical derivation, the reader is referred to [15]. logistic function in weka has been utilised for logistic regression [12]. naïve bayes classifiers is a probabilistic classifier which is based on the bayes theorem and being considered as a simple classifier [16]. in addition, it assumes independence in a naïve way [12]. the hypothesis is that the probabilities of each feature multiply is only valid if the events are independent. despite the simplistic assumption of independent attributes in real life, naïve bayes works very effectively when utilized to classify real life datasets [12]. the pseudocode for naïve bayes classifier [17] is displayed in fig.2. decisionstump, a fast decision tree learner which uses reduced-error pruning, was used. it builds one level binary decision tree with categorical or numeric class to perform the classification. decisionstump in weka was utilized to do decision tree. for more details about the implementation of decision stump, the reader is referred to [18]. oner classifier is simple but accurate classifier. oner algorithm generates one rule for each predictor in the data by forming a frequency table for each predictor against the target [19]. afterwards, the rule with minimal total error is selected. fig. 3 illustrates the pseudocode for oner algorithm [12]. iyden kamil mohammed al-khwarizmi engineering journal, vol. 16, no. 3, p.p. 110 (2020) 4 fig. 2. algorithm for naïve bayes classifier. fig. 3.the pseudocode for oner algorithm. the dataset used in this study has an imbalanced number of the three classes. class imbalances may limit the performance of machine learning classifiers [20]. in addition, different classification techniques are sensitive to the imbalanced data when the samples of one class in a dataset outnumber the samples of the other class. this may lead to biased models due to overfitting. to tackle the issue of class imbalance, we utilized synthetic minority oversampling technique (smote), proposed by chawla et al. [21] to equalize the number of classes in both classification stages. in smote, k-nearest neighbor (knn) is used to generate synthetic instances to oversample the minority classes while the size of the majority class is kept the same [21]. the weka filter ‘smote’ was used for both classification stages where the number of knearest neighbor was set to the default value of 5. in stage 1, the total number of instances became 256 for stage 1 and 221 for stage 2, after applying smote. to evaluate the performance of the breast classification, the exhaustive leave-one-out (loo) cross-validation (cv) was utilised in each stage of the classification. loo cv will prevent overfitting and bias in the evaluation of classification performance despite that it requires lot of computations compared to the 10-fold cv since it requires to go through all dataset. classification accuracy, precision, recall and were calculated given true positive (tp), true negative (tn), false positive (fp), and false negative (fn), as follows …(1) …(2) …(3) furthermore, we calculated matthews correlation coefficient (mcc) [22], given in eq. 4, which is an indicator used to evaluate the performance of classification quality where the output value is between the range -1 to 1; high value of mcc of 1 indicates an excellent classification. …(4) where the values of p and s are given below p = (tp + fp)/ (tp + fp + tn + fn) …(5) iyden kamil mohammed al-khwarizmi engineering journal, vol. 16, no. 3, p.p. 110 (2020) 5 s = (tp + fn)/ (tp + fp + tn + fn) …(6) c. selecting the best attributes for breast cancer classification in this study, correlation-based feature subset selection (cfs) [23] was utilised, for exploratory and interpretability purposes, to select the best attributes for each stage of the breast cancer classification. the main theory is that features which have high correlation with the class label but are uncorrelated with each other may represent the base for a good feature set. a feature evaluation formula is developed from the aforementioned theory. cfs then combines the developed evaluation formula with a heuristic search strategy and suitable correlation measure. the best classifier from the previous analysis (section ii.b) will be utilised alongside weka function attributeselectedclassifier, cfs (weka evaluator ‘cfssubseteval’) with the search method selected to be ‘best first’. it should be noted that ‘smote’ filter in weka was utilised in this part of the analysis to oversample the minority class for both stage-1 and stage-2. 3. results and discussion the minimum (min), maximum (max), mean and standard deviation (std) for the 20 attributes in this study are shown table 1 for the normal subjects, table 2 for the malignant patients and table 3 for the benign patients, respectively. there are large differences between some attributes for the three groups (such as ca15-3 b, cea-b and ca15-3 s) while other attributes have smaller differences (such as tbf and phs). table 1, the min, max. mean and std values of the 20 attributes for normal subjects (n=50). attribute min max mean std age 25 67 44.26 11.44 bmi 21.2 26.4 23.70 1.35 tbf 25.91 46.9 33.67 4.48 whr 0.63 0.95 0.78 0.08 mens. cycles/year 10 14 12.52 0.74 dur. of contracept./year 0 9 0.50 1.66 mens. cycle status 0 1 0.06 0.24 fut2 gene type 0 1 0.72 0.45 lewis blood type 0 2 1.24 0.52 es-b 11 97 50.48 25.70 pg-b 0.73 4 1.81 0.99 ca15-3 b 3.11 15.3 6.61 2.74 cea-b 0.59 2.94 1.78 0.57 tp-b 6.02 7.3 6.47 0.35 es-s 3.18 28.1 14.62 7.43 pg-s 0.24 1.8 0.68 0.41 ca15-3 s 0.5 2.68 0.79 0.41 cea-s 0.5 0.5 0.50 0.00 tp-s 0.05 0.28 0.14 0.04 ph-s 6.9 7.4 7.23 0.12 iyden kamil mohammed al-khwarizmi engineering journal, vol. 16, no. 3, p.p. 110 (2020) 6 table 2, the min, max. mean and std values of malignant patients (n=111). attributes min max mean std age 26 73 54.21 8.14 bmi 21.4 34.4 26.90 2.86 tbf 27.34 53.5 39.53 4.16 whr 0.67 1.1 0.88 0.11 mens. cycles/year 10 15 12.66 0.79 dur. of contracept. /year 0 18 3.52 5.08 mens. cycle status 0 1 0.31 0.46 fut2 gene type 0 1 0.39 0.49 lewis blood type 0 2 1.30 0.75 es-b 182 384 270.86 50.27 pg-b 0.62 4.9 1.42 1.16 ca15-3 b 18 79 52.44 18.79 cea-b 2.7 14.3 8.71 2.82 tp-b 7 10.8 8.76 1.22 es-s 52 111.2 77.68 14.78 pg-s 0.2 1.8 0.54 0.46 ca15-3 s 2.57 13.57 8.98 3.27 cea-s 0.5 2.7 1.21 0.56 tp-s 0.61 1.52 0.91 0.27 ph-s 5.4 7.2 6.06 0.58 table 3, the min, max. mean and std values of the 20 attributes for benign patients (n=20). attributes min max mean std age 28 58 45.15 7.86 bmi 21.1 32 25.63 3.18 tbf 26.36 44.91 35.17 5.01 whr 0.69 0.92 0.81 0.07 mens. cycles/year 11 13 12.10 0.45 dur. of contracept. /year 0 5 0.55 1.39 mens. cycle status 0 1 0.20 0.41 fut2 gene type 0 1 0.60 0.50 lewis blood type 0 2 1.25 0.55 es-b 18 96 59.75 30.89 pg-b 0.65 4.2 2.29 1.32 ca15-3 b 6.59 13.6 10.49 1.80 cea-b 1.02 5.71 2.46 1.15 tp-b 6.1 7.6 6.78 0.55 es-s 5.3 27.8 17.24 8.93 pg-s 0.2 1.6 0.84 0.54 ca15-3 s 0.69 2.35 1.51 0.47 cea-s 0.5 0.68 0.51 0.04 tp-s 0.12 0.28 0.17 0.04 ph-s 6.4 7.3 7.00 0.27 in order to investigate the performance of the four machine learning classifiers, table 4 and 5 shows the results of the classification of stage-1 and stage-2 in terms of precision, recall, accuracy and mcc for logistic regression, naïve bayes, decision tree and oner classifiers. naïve bayes classifier is outperforming other classifiers for stage-1 when we are classifying normal versus abnormal who had tumors as well as achieving similar performance for stage 2 for the case of classifying malignant and benign patients. iyden kamil mohammed al-khwarizmi engineering journal, vol. 16, no. 3, p.p. 110 (2020) 7 table 4, the results of stage-1 classification using different classifiers with loo cross validation. the best performer is shown in bold table 5, the results of stage-2 classification using different classifiers with loo cross validation. classifier precision recall ac mcc oner 1 1 100 1 logistic 0.996 0.995 99.5 0.991 naïve bayes 1 1 100 1 decision tree 1 1 100 1 the confusion matrix (cm) for the classification of breast cancer attributes is plotted with naïve bayes (best performer) classifier in table 6 and 7. the results in the diagonal of cm show the correct classification rates while the misclassifications are shown off-diagonal. there were only 15 cases (table 6) out of the 256 (with smote) cases that were misclassified for stage 1 while all the 221 (with smote) malignant and benign cases were classified correctly in stage 2 as shown in table 7. table 6, confusion matrix of the naïve bayes classifier for stage 1 after using smote predicted class actual group abnormal normal abnormal 116 15 normal 0 125 overall accuracy= 94.1 % table 7, confusion matrix of the naïve bayes classifier for stage 2 of the classification after using smote predicted class actual group malignant benign malignant 111 0 benign 0 110 overall accuracy= 100% when comparing the results obtained in this study with that in [9] who investigated 42 attributes and selected 26 attributes for the classification of three classes of breast tumors, we utilized smote to balance the classes unlike [9] who used imbalanced classes, which may cause overfitting, despite the high accuracy obtained on their work 98%. to find the best breast attributes that have the most influence for the classification of breast cancer in the stage 1 and 2, we utilizedcfs [23]. table 8 shows the best ranked selected attributes for stage-1 where the cfs selected 10 attributes while for stage-2, the best selected attributes were equal to 11. it is worth noting that the classification accuracy with the best selected attributes with loo was equal to 94.9 %, slightly higher than that of the full set of attributes (94.1%). in stage-1 for the classification of normal or abnormal cases, bmi, menstrual cycle status, and fut2 gene type were the 3 most important ranked attributes, selected by the cfs. as for stage-2 for the classification of benign and malignant cases, the selected features were age, whr and number of menstrual cycles per year. it can be noted also that the common five attributes that are shared between stage-1 and stage-2 are cea-b, ca15-3 b, ca15-3 s, tp-b and es-s. cea-b is tumor biomarker that is derived from blood; it is not specific for breast tumor. however, ca15-3 b is regarded as tumor biomarker and it is specific protein biomarker for breast cancer. moreover, ca15-3 s and es-s are classifier precision recall ac mcc oner 0.914 0.914 91.4 0.828 logistic 0.934 0.934 93.4 0.867 naïve bayes 0.948 0.941 94.1 0.889 decision tree 0.930 0.930 93 0.860 iyden kamil mohammed al-khwarizmi engineering journal, vol. 16, no. 3, p.p. 110 (2020) 8 newly derived breast tumor biomarker that is derived from saliva. it is highly promising since it is non-invasive based on easy to acquire salivary sample. table 6, the results of the best ranked selected attributed with cfs with naïve bayes classifier. the attributes that are common the two classification stages are shown in bold. stage-1 stage-2 1 bmi age 2 mens. cycle status whr 3 fut2 gene type mens. cycles/year 4 ca15-3 b lewis blood type 5 cea-b es-b 6 tp-b ca15-3 b 7 es-s cea-b 8 pg-s tp-b 9 ca15-3 s es-s 10 ph-s ca15-3 s 11 tp-s 4. conclusion in this paper, 20 breast cancer attributes have been collected for the iraqi women and utilized to test the performance of two-stage classification withfourclassifiers where the attributes are classified into normal and abnormal cases in the first stage. if the case was abnormal, then the second stage of the classification is performed to predict either the patient has a malignant or benign tumor. synthetic minority over-sampling technique (smote) was utilized to deal with the problem of class imbalance. classification accuracy of 94% for stage-1 and 100 % was achieved with naïve bayes classifier and loo cross-validation. the level of ca15-3 protein in blood (ca15-3 b) and saliva (ca15-3 s), and carcinoembryonic antigen level (cea-b) and total protein (tp-b) in blood and also estrogen level (es-s) in saliva, were the best selected features with cfs for both classification stages which show the importance of those parameters in predicting malignant breast tumors. acknowledgments the first author would like to thank the contribution of dr khalid mahdi salah, university of mustansiriyah for his comments on the data collection. the authors are grateful for the reviewers for their insightful comments. conflicts of interest disclosure authors declare that there are no conflicts of interest. 5. references [1] n. a. s. alwan, “breast cancer: demographic characteristics and clinico-pathological presentation of patients in iraq,” 2010. 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[18] c. sammut and g. i. webb, eds., “decision stump bt encyclopedia of machine learning,” boston, ma: springer us, 2010, pp. 262–263. [19] s. sayad, “tutorial on oner classifier.” [online]. available: http://www.saedsayad.com/oner.htm. [accessed: 28-jan-2019]. [20] n. japkowicz and s. stephen, “the class imbalance problem: a systematic study,” intell. data anal., vol. 6, no. 5, pp. 429–449, 2002. [21] n. v chawla, k. w. bowyer, l. o. hall, and w. p. kegelmeyer, “smote: synthetic minority over-sampling technique,” j. artif. intell. res., vol. 16, pp. 321–357, 2002. [22] p. baldi, s. brunak, y. chauvin, c. a. f. andersen, and h. nielsen, “assessing the accuracy of prediction algorithms for classification: an overview,” bioinformatics, vol. 16, no. 5, pp. 412–424, 2000. [23] m. a. hall, “correlation-based feature selection for machine learning,” 1999. ��� 3ا���د، �16 �� ا���ارز�� ا������� ا�� �� ا �ن ���� ����� ،10 -1 )2020( 10 ��تا��!ا�1 ����0ء��.-!ات ا���� � +ورام ا�)�ي �&%��$ #�" �! ��� ***�3�4! ا��2د !وا **#�� �0� ا������ * ا �ن ���� ���� .�!-� ,+�اد /()'� ا�&���� ا�%$ارز!� / �� ھ���� ا��� ا������*،** ***����/)�8 ا�/��7ةا�/ /.�!-� اد0�5ه /!-&� ا2�3�2ت ا�0 /� /()'� ا�& aydenel_1969@yahoo.comا��0;� ا078�2و�5: ali.altimemy@kecbu.uobaghdad.edu.iq**ا��0;� ا078�2و�5: javier.escudero@ed.ac.uk :�5ا��0;� ا078�2و*** �� ا��5 ;��� ا�j! 0'?8 ا�$b'�ت. إن ا�f'%g7 ا�/�08 ��0ط�ن ا�?�ي ,��7%�ام ا�-d!�ت ا��'$;� ا�/����� و/'�b c ا����ء �&�ف: ;-0�7 �0ط�ن ا�?�ي �0ط�ن !ا ا 07اح �)$رم � ;�&n ا�-dج ا�/�08 �)/0ض ، !/� ;j! n(o !-�ل ا�$b'�ت. ا�+0ض !j ا��را�� ا����'� ھ$ ���'j ا�f'%g7 ا�/�08 �)?�ي !dl jل j'7(r0! s(t u'� ./0wxات ا��'$;� vورام ا�?�ي �-'�� !j ا����ء ا�-0ا '�ت)��3 ! uَّ�3ُ� ، sو�vا �(r0/ا� �b .��[ا �b!d ا�?�ي ا��0ق: �b ھ`ه ا��را�� ، �� ا 07اح 5_�م �3�'j'7(r0! s(t u وا��7lره !^ أر,-� !3�\�ت �)7-) �'b0اc$/;ا�� fd�3%ا�(ا� fd�3%ت ا��!$ا���'t j! �3(%7�//�ت ا��ت وا���'t j! �3(%7�/ (2ت ط�'-'� �ا�)-�ب���'h0/i0lوا �7; j'r �b ، 8g, �!ا�?�5'� إ �(r0/ا� �b �'-'0 ا���'c 2ت ا�?�ي�r u'�7� ا�7%�ام n ورم�3; .�'/r أو j'�l� 0ونg-/�ت ا����7ر ا�l2 �&-/. ��0ط�ن ا�?�ي ا��7 � � ا�7%�ام� ، kذ� s(t وةdt . 07حo/ا� u'�n'(�� �b ا��b�g87 �)-?$ر s(t أnnb ا�/'mات (cfs) ا7l'�ر ا�/'mات ا�/�7��ة إ�s ا2ر���ط أداء 5_�م ا�37 j'7(r0! s(t u'��_�م ا�37�. ����, u'�� ��o'o د � ا�37� :pd�7�3�u!^ ٢٪ �)/r0)� ١٠٠٪ �)/r0)� اvو�s و ٩٤ا�!naïve bayes .0ىlvا �wd?ا��0ق ا� s(t ا�`ي �\$ق kذ� sإ� �b�hx�, دت�r ، cfs j! 0ة'+y �'t0b �t$/z!/�ت�ا� nnb��7رھ� أt�,�/lت�/� n) j', j!٢٠ �/� sو�vا j'7(r0/ا� j! n8� .وا�?�5'� �o� :�yd%ا�o'o�� �� j'أھ/'� ا��0و� �nً;ھ`ه ا��را�� أ pd�75 0&_� .ا�/�08 �$رم ا�?�ي f'%g7ا� j'��� �b ة�t��/��, �-� �7وا� �'��t u'� د � �3 ca15-3 �50ط��ا� �n7�/7$ى ا��! k�`)ا�)-�ب وا��م و �b ا��م �b ورام ا�?�ي�|, x��7(. (microsoft word \332\341\355 \332\307\343\321111-123) al-khwarizmi engineering journal al-khwarizmi engineering journal,vol. 13, no. 4, p.p. 111123 (2017) the computational fluid dynamic simulations for gangrene disease in diabetic foot ali amer ali al-allaq office reconstruction and projects/ ministry of high education and scientific research ali_martial85@yahoo.comemail: (received 4 january 2017; accepted 25 may 2017) https://doi.org/10.22153/kej.2017.03.003 abstract the diabetic foot is considered one of the long term diabetes complications caused by a defect in blood vessel and nerve system. this requires dealing with diabetic foot with professional medical care, so as to prevent its development in advanced stages which could end to gangrene and amputation of the foot. this study has been initiated through follow-up of twelve patients with diabetes and the presence various occlusions in lower limb artery. one patient from them was chosen for investigation, this patient has stenosis in popliteal artery and presence multiple stenosis in superficial femoral artery. this study based on analysis present case of patient and prediction for progress stenosis in superficial femoral artery till arrive semi total occlusion of the artery and interpret the occurrence of gangrene in the lower limb. the geometrical values of the artery and stenosis were acquired measured directly from the patient by using angiography device. the disease of gangrene and artery stenosis in diabetic foot has been investigated by using a simulation program (ansys fluent cfd). the results of study by using four models with (75%, 90%) stenosis from original artery diameter in the healthy patient case are presented and compared with present and healthy case (without stenosis). it has been appeared, with presence of multi stenosis in superficial femoral artery for diabetic foot, and by assuming the blood to be a newtonian fluid, a significant increase in the blood velocity and wall shear stress in the area of stenosis compared with non stenosis region. the blood flow rate was decreased constrained as the degree of stenosis increased and vice versa. peak blood velocity is about (0.88) m/sec for healthy artery, it reaches (2) m/sec for a 42.4% stenosis (current case).the maximum velocity values were (10.36, 49.31) m/sec for 75%, 90% stenosis respectively. the maximum wall shear stress at the stenosis region varies from (1094) pa in the 75% stenosis to (15916) pa in the 90% stenosis against a values of (6.36, 380.5) pa in the healthy artery, current case respectively. keywords: diabetic foot, artery stenosis, gangrene, blood velocity, wall shear stress, mass flow rate, cfd, femoral artery. 1. introduction diabetes is one of the most prevalent disease in the worldwide, that affects all ages and nonconfined on a specific category or a particular age group. diabetes is a chronic disease, it occurs when the pancreas does not produce insulin in sufficient quantity, or when the body cannot effectively use the insulin it produces. insulin is the hormone that regulates blood sugar levels. the chronic hyperglycemia (high blood sugar level) of diabetes is associated with long-term complications in the eyes, kidneys, nerves, and blood vessels [1]. blood vessels are part of the circulatory system, which is concerned in the transfer blood to the body tissue. there are three types of blood vessels: arteries, capillaries and veins. arteries mission is the delivery of oxygen and nutrients, and the most important glucose, which make the cells and then the tissues that make it up, surviving, so the blood outage or delay arrival at the tissue constitutes a real danger to the tissue or organ, according to the its ali amer ali al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 111123 (2017) 112 function. gangrene is the expression used to depict the death of tissue or necrosis due to failure and blocked blood circulation, usually followed by decay and corruption, a serious potentially lethal complication, which has been well known to generations of physicians for epochs [2]. there are two main kinds of gangrene, wet and dry gangrene. gas gangrene in some sources assumed as a third type of gangrene in some classify as the type of wet gangrene. gangrene may influence superficial or deep tissues. superficial gangrene frequently impacts distal parts of the body such as fingers and toes [3]. gangrene ordinarily appears the same in both the person with diabetes and the person without diabetes a like [1]. the diabetic patient foots has the possibility endanger of pathologic effect , such as infection , demolition of deep tissues parallel with abnormalities of neurologic ,ulceration, different levels of peripheral vascular disease with metabolic complexity of diabetes in the lower limb [2].diabetic persons have a 15 times higher risk of lower extremity amputations than non diabetic individuals [4]. amputation is the final outcome of a cascade of diabetic foot lesions [2].abnormalities function of endothelial cell lining the artery wall can expose the arterial system to atherosclerosis and its related reverse effects [5]. atherosclerosis is progressive growth of atherosclerotic plaques in the artery. in progress stage of atherosclerosis, plaques will become stenotic and cause progressive obstruction of the arterial lumen [6], as shown figure (1). many factors have been involved in atherosclerosis pathogenesis, include hypertension, cigarette smoking, diabetes, hyperlipidemia, and hyperhomocysteinemia [7]. the peril of the foot amputations or ulcers is raised in patients who have diabetes greater than or equal to 10 years, have poor regulation of blood sugar, or have cardiovascular disease [8]. the most common pathway linked with the development of diabetic ulcers involves peripheral neuropathy; approximately 30% of diabetics have moderate to significant forms of nerve harm. absence sensation leads to unfeeling foot more vulnerable to pressure points and repetitive activity [9,10]. fig. 1. show total femoral artery occlusion for man has (65) years old with diabetes history, the patient diagnosed in al-shaheed gazi hospital/ department of radiology at 2016. the diabetes is widespread widely in the world and has a direct impact on human health and the sustainability of his life , so there are a lot of medical researchers that interested about diabetic and focused to pathological cases associated with this disease, such as diabetic foot and gangrene. suguru et al 2001 [11] presented report about follow-up 27 patients with diabetic foot, average age 67 years. all patients in this study suffer type (2) of diabetes, diabetic neuropathy, and more than 60% of these patients have arteriosclerosis disease. the follow-up period was (2 years and 3 month ), amputated 35 of lower limbs from 27 patients , thirteen patients died during 1 day to 1187 days after the amputate operation. edward et al 2001 [12] presented study the relationship between diabetes and peripheral arterial disease. this investigation has showed that diabetic patients suffered peripheral arterial disease in the lower limb region with risk of amputation and probability died at a younger age than nondiabetic patients. the other point of study conclusion showed the worse disease in diabetic patients happen in the femoris artery. paulo et al 2005 [13] presented a case of ulceration and leg ischemia caused by progressive stenosis in the right common femoral artery. this study assumed that frequent arterial damage caused the effect of diabetes result the cumulative common femoral artery stenosis. all the above researches confirms the relationship between diabetes and lesions of arteries in the important parts of the human body as a result of this disease ,an example that the arteries of the foot .in some cases diabetic disease leads to the amputation of a damage part cause ali amer ali al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 111123 (2017) 113 lack or reduced access of blood nutrition to this part . atherosclerosis are early development in the diabetic patients and more dangerous than nondiabetics. artery disease is a dangerous, whether the artery stenosis or aneurysm. its direct impact on human health , so this disease has led to the attention of a lot of the researchers to work engineering analysis of the disease by simulating what happens inside the defect artery and investigation about all parameter that change from normal case. mingxiu 2006 [14] investigated the biomechanical forces and vessel wall motion with the advancement of stenosis acuity under realistic loading conditions by using coupling of the computational fluid dynamics packages fluent and the finite element modelling packages abaqus and software program (matlab) script. the results showed extreme wall shear stress is about 6 pa for healthy arteries, it reaches 45 pa for a 30% stenosis (by diameter),and for more than or equal to 50% stenosis. wall motion was increasingly constrained as the degree of stenosis increased. luisa et al 2011 [15] studied the blood velocity and wall shear stress of the artery stenosis 3d model, use computational finite element and navier-stokes equations to perform this investigation. simulated outcomes are evaluated and compared with literature data acquired from ultrasound device measurements. sónia et al 2012 [16] reported a preliminary numerical study of blood flow in a bifurcation channel with stenosis. the package program (ansys) was used to execute the numerical study. the blood flow in a channel provided with a moderate stenosis (65% of obstruction) was compared with that in a severe stenosis (90% of obstruction). for a severe stenosis, the static pressure drop was higher, the difference between mass flow rates in both branches of the bifurcation is also higher, and small recirculation parts were observe following the stenosis region. padukkage et al 2014 [17] studied a comparison between an axisymmetric stenosis model in the common femoral artery and an eccentric model in terms of wall shear stress distribution and oscillatory shear index. blood was assumed in this study a newtonian fluid. this study concludes that when implement computational fluid dynamics simulation to determine the regions that are more susceptible to subsequent stenosis. it was unwise to assume complete symmetry of the blood obstruction in the artery. nabeel et al 2017[18] presented numerical study the effects of aneurysm and stenosis in left coronary artery on the blood velocity, mass flow rate of blood and wall shear stress of artery by using simulation program (ansys fluent) .this investigation reached several conclusions, including that insufficiency blood supply by the coronary arteries to the heart muscle with stenosis presence leads to ischemia and myocardial infarction. the stenosis of the arteries was impact on the blood velocity, wall shear stress of artery and lack that occurs in the desired amount of blood delivered to the body organ. from relationship between diabetes disease and gangrene the idea of this research was emerged. the present study investigates the influence of artery stenosis in diabetic foot on the occurrence of gangrene. 2. materials and methods 2.1. patient data selection twelve patients with diabetes and peripheral artery disease were follow-up in the department of radiology for evaluation of arterial disease in the lower extremities. the imaging techniques computed tomography and x-ray angiography were used for diagnosis cases study. angiography is a diagnostic, therapeutic form concerned with circulation system diseases. in this technique, the vessels of concern are opacified by injection of a radiopaque contrast agent. contrast substance is required to opacify vessel structures because the radiographic contrast of blood is essentially the same as that of soft tissue [19].these 12 patients, 4 woman and 8 men, had a mean age of 62 years and a mean duration of diabetes of 10 years. the follow-up duration was 15 month. the characteristics of the patients are presented in table (1) ali amer ali al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 111123 (2017) 114 table 1, details of patients information. this investigation was performed on the patient no. (1) shown in the above table. this patient was female, has age (69) years, heavy smoker, diabetes existent about ten year ago. she was suffering from pain and claudication in the right lower limb, when the diagnosis by angiography device showed a stenosis occurs in the femoral and popliteal artery. this patient has been chosen be investigated for many reasons, the artery stenosis existence more than one region, in femoral artery and popliteal artery and presence multiple stenosis in femoral artery, as shown in figure (2). patient no. age sex location of stenosis percentage of stenosis notes for patient case site of diagnosis diagnosis device 1 69 female right femoral artery 38% 42% multi stenosis multi stenosis along femoral artery , progress to total occlusion in popliteal artery al-shaheed gazi hospital / department of radiology angiography/ siemens axiom artis right popliteal artery 90% 2 80 female right femoral artery 67%-100% amputated two toes from right foot by cause gangrene 3 36 male right common iliac artery 75% 4 58 male right popliteal artery 95% slight stenosis in right femoral artery 5 71 male left femoral artery 99% distal femoral artery takes blood from collateral artery 6 70 male right femoral artery 50% 7 65 male right femoral artery 100% additionally ,stenosis occurs in collateral artery 8 73 male right common iliac artery 57% amputated the left leg ibn alnafees hospital / department of radiology computed tomography/ toshiba aquilion 9 65 female left femoral artery 65% additionally, the presence acute stenosis in the coronary artery 10 50 male right aorta + common iliac artery 100% amputated the left leg caused by total stenosis in left femoral artery 11 52 male right common iliac artery 100% chronic stenosis in common iliac artery ,femoral artery takes blood from collateral artery 12 57 female right femoral artery 100% femoral artery bypass surgery was performed to treatment the total stenosis in artery, and then stenosis occurs in bypass itself. ali amer ali al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 111123 (2017) 115 fig. 2. show multiple stenosis in femoral artery for female patient has (69) years old, heavy smoker, with diabetes history, the patient diagnosed in alshaheed gazi hospital/ department of radiology at 2016. 2.2. computational model anatomically, the common femoral artery bifurcation in two branches the superficial femoral artery and profunda femoris. the superficial femoral artery is a direct extension and locates the same axis of the common femoral artery [20]. the superficial femoral artery is the most common site of multiple stenotic lesions, so the profunda femoris tends to be spared [21].the superficial femoral artery was studied in this search, shown in figure (2).all real dimensions, length, diameter and percentage stenosis of artery taken directly from angiography device when the patient number (1) in the table (1) under diagnosis. the length of the selected part of artery for this study was (14) cm and diameter (4.34) mm. the stenosis diameters were (2.7, 2.5) mm with length (1) cm in stenosis area (1) and area (2) respectively, as shown in figure (2). this study based on the simulated the present patient case and future prediction of the artery stenosis progress until access the semi total occlusion of artery and compare with healthy case (without stenosis), progress of stenosis assumed two stages,stenosis (75%,90%)from orginal diameters with (1.085, 0.434) mm respectively ,as shown in figure (3). 2.3. physiological parameters the behavior of the blood in the human femoral artery has been assumed newtonian fluid. it is assumed that when the diameter of the artery is large compared to the size of suspension particles, blood can be treated as newtonian and viscosity can be considered as constant [14].nonnewtonian effects are only considered in small vessels with an internal radius less than (0.5) mm [14,22]. so the assumption of newtonian flow in this study can be considered valid. suitable rheological parameters for human body were applied with a blood density of (1060) kg/m3 and constant blood viscosity of (0.0035) pa s [23]. the measurement of blood velocity in human arteries has possibility use both in physiologic studies and in the estimation of patients for arterial disease, the blood velocity information can be obtained by ultrasonic techniques. the blood velocity was applied as an inlet boundary condition in superficial femoral artery, the peak systolic average velocity was taken as range (60) cm/sec as mention in [24]. fig. 3. show design selective length of right superficial femoral artery (a) healthy case (b) current case (c) 75% stenosis (d) 90% stenosis (semi total occlusion). 2.4. the computational method of hemodynamic analysis a finite-volume method package (ansys fluent code version (15.0) was used to solve the equations of navier-stokes, continuity equation, momentum conservation [25] on a microsoft windows (7) 64-bit ali amer ali al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 111123 (2017) 116 machine, 4gb ram with an intel core i3 cpu. a mesh independence test was carried out depending on the mass flow and velocity of blood using three grid sizes (500,000-750,000 and900,000) of tetrahedral elements, this leads to the selection of mesh size of (900,000) concentrated near to predict boundary layer of velocity gradient . a finite-volume based technique that consists of the following steps is used for solution :(a) a grid is generated on the domain, which was previously explained. (b) for velocity, pressure, and conserved scalars, algebraic sets of equations are constructed by the integration of the governing equations on each control volume. (c) discretized equations are linearized and solved iteratively. 3. results and discussion the performed this investigation reflected the effect of stenosis on the blood flow characteristics. this impact is very significant and complex to study in vivo, for this purpose emanate the numerical study. all changes that occur on the blood velocity, blood flow rate and wall shear stress in the superficial femoral artery due to the impact of diabetes and incidence artery stenosis to reach stage of gangrene in human foot were investigated and calculated by use ansys (cfd) simulations program. the variations of blood velocity is one of the important factors for indication of artery stenosis, for this reason the velocity studied on five different axial locations along the length of the artery to understand and precision description of events inside the artery under various pathological conditions of the superficial femoral artery and compartment with healthy case (without stenosis). the axial location sections are chosen related to the presence stenosis lesions area in this position and compare them with same location in the healthy artery. the sections (s1.s3) are located before (1) cm from first and second stenosis area, (s2, s4) are located at middle of stenosis region. also the sections (s3, s5) are located after (1) cm from first and second stenosis area respectively, as shown in figure [4]. fig. 4. the section lines at (a) first stenosis area , (b) second stenosis area . the velocity of blood is the rate of displacement of blood per unit time. the blood vessels of the cardio vascular system vary in terms of diameter and cross section area. these variations in diameter and area in turn, have deep effects on velocity of blood as eq. (1) [26].the other factors that impact the blood velocity profile include the entrance effect, skewing, vessel curvature, turbulence, stenosis, acceleration, and secondary flows [19]. the equation (1) shows the inverse relationship between diameter of artery (or diameter of stenosis) with velocity, this explain the increase of blood velocity in the stenosis region. 3 2 / sec sec q cm cm v a cm = ↔ = … (1) the blood velocity can be seen in figures (5, 6, 7, 8, 9 and 10) increasing in the center region of blood flows in vessels due to the effect of intima friction with cellular component of the blood, intima refer the inner layer of blood vessel wall. poiseuilles law as mention in eq. (2), states that resistance to blood flow in a blood vessel proportionately varies directly with length of vessel and viscosity of blood and inversely with fourth power of radius of lumen of vessel [27]. )2( ... 4 8l r r η π = the peripheral resistance define, is the frictional resistance offered by the circulatory system to the flow of blood. blood flows in vessels in a series of concentric layers with ever increasing velocity in the center. the various layers moving at different velocities cause [27]. the flowfrictional resistance to ali amer ali al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 111123 (2017) 117 fig. 5. variation of velocity at section (s1) in superficial femoral artery for multi case of stenosis and compare with healthy case. fig. 6. variation of velocity at section (s2) in superficial femoral artery with (a) 75 % of stenosis compare with current and healthy cases, (b) with 90 % of stenosis. fig. 7. variation of velocity at section (s3) in superficial femoral artery for multi case of stenosis and compare with healthy case. fig. 8. variation of velocity at section (s4) in superficial femoral artery with (a) 75 % of stenosis compare with current and healthy cases, (b) with 90 % of stenosis. fig. 9. variation of velocity at section (s5) in superficial femoral artery for multi cases of stenosis and compare with healthy case. ali amer ali al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 111123 (2017) 118 fig. 10. variation of contours velocity (m/sec) at (a) healthy case, (b) current case, (c) 75 % of stenosis (d) 90 % of stenosis. the change in diameter of the artery like stenosis leads to several differences in the natural appearance of the blood flow. laminar flow is the normal case throughout most of the circulatory system and is described by concentric layers of blood moveable in parallel along of a blood vessel. turbulent flow is a flow case characterized by anarchic and rapid changes in pressure and flow velocity. turbulence occurs when smoothly flowing, laminar flow is disrupted, distal to stenotic [28]. as the stenosis becomes high stage, turbulence is likely to occur downstream of the stenosis. the turbulent intensity is also larger in a tighter stenosis [29]. turbulence in blood flow increases the energy desired to propel blood flow because it increases the loss of energy in the form of friction with artery wall, which produce heat [30]. in areas of turbulence, platelets and endothelial cells may be activated, leading to thrombosis in artery [31].in stenosis area can be seen, an increase in blood velocity and change the normal form of blood path in addition , the energy dissipated or lost in this region as a result of the turbulent flow .so we can imagine the extra load that falls on the heart as a result of this multi stenosis also the disruption in the amount of blood that expected access in the post-stenosis stage whether an artery or effective organ, shown in figures (11) and (12). fig. 11. turbulent intensity countours (%) in superficial femoral artery (a) healthy case, (b) first stenosis area at current case, (c) second stenosis area at current case. fig. 12. turbulent intensity countours (%) in superficial femoral artery (a) first stenosis area at 75% of stenosis ,(b) second stenosis area at 75% of stenosis , (c) first stenosis area at 90% of stenosis , (d) second stenosis area at 90% of stenosis. the impact of stenosis in arteries of diabetic foot on the wall shear stress (wss) distribution and magnitude for various cases was studied. the vascular system cells are permanently exposed to mechanical forces (hemodynamic) due to the blood flow. the forces produced in the vessels comprise the fluid shear stress or frictional force ali amer ali al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 111123 (2017) 119 act on the blood flowing tangentially across the endothelium, a pure normal stress caused by a hydrodynamic pressure differential across the vasculature wall , and a tensile stress caused by circumferential vasculature wall deformations [19]. in this research, (wss) was computed along the inner wall of the superficial femoral artery at two longitudinal lines (wss1, wss2) located on the first and second stenosis area respectively, as shown in figure (13). the purpose of longitudinal lines locations was selected synchronize to the presence stenosis in this area and compare it with the same location with healthy artery. the executed results show the variation of (wss) for the selected stenosis cases at the chosen locations on the artery as shown in figures (14), (15) .the value of (wss) depends on the magnitude of this velocity gradient at the vessel wall. that (wss) is measured adjacent to the vessel wall and for the cylindrical tube is calculated as [32]. 8 v wss d η = … (3) fig. 13. selected locations of wall shear stress in superficial femoral artery. fig. 14. variations of wall shear stress along the first longitudinal section (wss1) of superficial femoral artery (a) for healthy and current cases (b) with 75 % and (90) % of stenosis. fig. 15. variations of wall shear stress along the second longitudinal section (wss2) of superficial femoral artery (a) for healthy and current cases (b) with 75 % and (90) % stenosis. from equation (3), the value of (wss) is directly proportional with blood velocity and blood viscosity and inversely proportional to the diameter of vessel. thus the stenosis of artery or reduce in vessel diameter will have a large impact on the (wss) as seen in figures (14), (15).thus a slight change in vessel diameter will have a big impact on (wss) .shear stress has an instant impact on the endothelial cell, which reply to rise in shear stress by secretion nitric oxide, leads to vasodilatation and relaxation smooth muscle cells of artery wall [33]. the effects of high wall shear stress orientation of endothelial cells and the ali amer ali al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 111123 (2017) 120 subsequent production and release of factors that prevent coagulation, allow migration of white blood cells, and induce smooth muscle proliferation, while simultaneously encourage endothelial cell survival [7]. for this reasons, the physician is given advice to patient or healthy person, to work daily sport or continuous movement if possible because this effectiveness lead to increased blood velocity and increase (wss), then increase flexible of artery and vasodilatation occurs. vasodilatation is dilation of blood vessels led to raise of blood nourishment to tissues that necessity it most. gangrene is disease caused lack or obstruction of the blood supply to organ. it is necessary to know and measure the amount of blood that arrive in the event of an artery stenosis in diabetic foot and compare it with the healthy case (without stenosis) as shown in figure (16).mass flow rate of blood is defined as the mass of blood passes per unit time. mass flow rate is dependent on many factors such as blood velocity, area of flow, and blood density, as eq. (4) [23]. m=ρ*v*a … (4) fig. 16. variation of the mass flow rate of blood in superficial femoral artery at second stenosis area for five percentage of stenosis, 0% stenosis (healthy case), 42.4 % stenosis (current case), 75% stenosis, 90% stenosis and 100% stenosis (total stenosis). the mass flow rate in figure (16) have been calculated by apply blood density, area of stenosis and blood velocity in each stenosis cases in eq. (4), the values of blood velocity were taken from output result data of execute simulation in section (s4) for each selected case, when total stenosis (area of flow equal zero) causing the value of the mass flow rate in artery shift to zero. the blood arrives to superficial femoral artery from aorta by common iliac artery. the superficial femoral and popliteal arteries are the most vessels usually influenced by the atherosclerosis. atherosclerosis influence the lower limbs is the general form of peripheral vascular disease. it leads to clinical cases extending from intermittent claudication or pain at rest to non-healing ulcers and gangrene [34] .most cardiovascular risk factors for patient with peripheral arterial disease are comparable for patients with diabetes alone. general agreement strongly supports that both peripheral arterial disease and diabetes are related with considerably increased risks of cardiovascular disease [5]. the superficial femoral artery is undergoing to different forces, such as flexion, compression, extension, contraction, and torsion, which have caused many therapies to failure. the health of superficial femoral artery has also been important for saving patients’ quality of life and limbs. various ways exist for therapies the superficial femoral artery, angioplasty balloons, covered stent grafts, plaque atherectomy instruments (endovascular surgery technique for removing atherosclerosis from blood vessels), and a numerous of chronic total stenosis instruments all supply endovascular doctors with wide options according to patients case. [35]. 4. conclusions 1. in the stenosis region occurs turbulence blood flow. the blood velocity in this region will become so fast and inverse proportion relationship with diameter of stenosis, and vice versa. 2. increase blood velocity in stenosis region accompanied with increment wall shear stress. vasodilatation has direct affect by increase wall shear stress cause impact on the internal tissue of artery lumen. 3. blood flow rate is suffered irregular and disorder by cause of multi stenosis in superficial femoral artery, this leads to lack arrive blood and insufficiency nourishment that needed to sustain life of foot tissue. 4. stenosis of artery and reduce necessary blood that arrive to organ by this artery leads to gangrene of the affected organ because the death of living cells as a result of non-arrival of the necessary nutrition. notation unit meaning symbol m/sec blood velocity v pa pressure p 3kg/m density ρ ali amer ali al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 111123 (2017) 121 ml/sec blood flow q 2cm cross section area of artery a 3pa sec/cm resistance r cm length of vessel l pa sec viscosity of blood η cm radius of blood vessel r cm diameter of vessel d pa wall shear stress wss kg/sec mass flow rate m 5. references [1] chiristos s. mantzoros, “obesity and diabetes”, humana press, totowa, new jersey, pp. (136,225), 2006. [2] alexander a. vitin, “gangrene – current concepts and management options”, in tech, pp.i, 2011. [3] dafiewhare o.e., agwu e., ekanem p.,ezeonwumelu j.o.c., okoruwa g. and shaban a., “a review of clinical manifestations of gangrene in western uganda”, intech,pp114,2013. [4] randi s. most, pomeroy s., “the epidemiology of lower extremity amputations in diabetic individuals”, diabetes care, vol. 6, no. 1, pp.8791, 1983. [5] american diabetes association, “peripheral arterial disease in people with diabetes “, diabetes care, vol. 26, no. 12, pp.3333-3341 2003. [6] erik w., andries d. van der m., marijke j. e. kuijpers., jean p. f., albert van den b., johan w. m. heemskerka, “atherosclerotic geometries exacerbate pathological thrombus formation poststenosis in a von willebrand factor-dependent manner”, proceedings of the national academy of sciences (pnas), ,vol. 110 , no. 4 pp. 1357–1362, 2013. 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[12] edward b. jude, samson o. oyibo, nicholas c., andrew j.m. boulton, “peripheral arterial disease in diabetic and nondiabetic patients”, diabetes care, vol. 24, no.8, pp.1433-1437, 2001. [13] paulo g., thomas w., sotirios t., “rapid progression of common femoral artery stenosis leading to development of ischemic foot ulcer following repeated ipsilateral arterial access”, catheterization and cardiovascular interventions :66,pp.487–490 ,2005. [14] mingxiu li, “numerical simulation of blood flow and vessel wall stresses in stenosed arteries”, doctor of philosophy thesis, the university of edinburgh, 2006. [15] luisa s., catarina c., carlos a., rui c., “computational techniques and validation of blood flow simulation”, wseas transactions on biology and biomedicine, issue 4, vo. 8, pp.145-155,2011. 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[21] kendra m. merine, anton n. sidawy “diabetic foot lower extremity arterial disease ali amer ali al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 111123 (2017) 122 and limb salvage” chapter 11, “anatomic distribution of atherosclerotic lesions as influenced by diabetes and other risk factors”, first edition, lippincott williams & wilkins, pp.130,2006. [22] wilmer w. nichols, michael f o’rourke, charalambos vlachopoulos, arnold p hoeks, robert s reneman, “mcdonalds blood flow in arteries theoretical, experimental and clinical principles”, sixth edition, hodder arnold, pp.17, 2011. [23] tiffany c. , richard f., “mechanobiology handbook”, chapter two , “fluid mechanics”, crc press taylor & francis pp.24-30 ,2011. [24] reva arnez curry, betty bates tempkin, “sonography: introduction to normal structure and function”, “vascular technology”, elsevier health sciences, fourth edition, pp. 623, 2015. [25] ansys fluent, version 15, ansys inc. 2014, "fluent 15 theory guide", 2014. [26] [26]. linda s. costanzo, “physiology”, 4th edition, saunders elsevier, pp.115-117, 2010. [27] ratan, “handbook of human physiology”, circulatory system, jaypee brothers publishers, pp.90-91, 2004. [28] sandor ianos bernad, romeo susan-resiga, elena bernad,dan gaita, gheorghe i. mihalas, ioan munteanu, “computerized study of the blood flow in arterial stenosis”, tmj, vol. 54, no. 2,pp.142-145, 2004. [29] s. a. berger, l-d. jou, “flows in stenotic vessels”, the annual review of fluid mechanics, 32, pp.347–382, 2000. [30] richard e. klabunde, “cardiovascular physiology concepts”,2nd edition ,published by lippincott williams & wilkins,pp.27-28, 2011. [31] sue e. huether, kathryn l. mc cance, “ pathophysiology the biologic basis for disease in adults and children “ ,6th edition , mosby elsevier,pp.1055,2014. [32] robert m. winslow, “blood substitutes “, elsevier academic press, pp.93, 2006. [33] thomas j. fogarty, rodney a. white, “peripheral endovascular interventions”, springer science & business media, pp.17, 2013. [34] jeffrey i. weitz, chair; john byrne, g. patrick clagett, michael e. farkouh, john m. porter, david l. sackett, d. eugene strandness jr ,lloyd m. taylor , “diagnosis and treatment of chronic arterial insufficiency of the lower extremities: a critical review”, circulation, 94,pp.30263049, 1996. [35] tanvir bajwa, paramjit romi chopra, rick coats, dennis gable, paul jones,mark mewissen, amir motarjeme, james park, ashish pershad, richard saxon, darren schneider, peter soukas, “endovascular repair of the superficial femoral artery”, supplement to endovascular today,pp.1-23 , september 2008. )2017( 111-123، صفحة 4، العدد13دجلة الخوارزمي الهندسية المجلم علي عامر علي 123 محاكاة ديناميكية الموائع الحسابية لمرض الغرغرينا في القدم السكرية علي عامر علي العالق ة التعليم العالي والبحث العلميوزار/ دائرة االعمار والمشاريع ali_martial85@yahoo.comالبريد االلكتروني: الخالصة وهذا يتطلب التعامل مع القدم السكري واحدة من مضاعفات مرض السكري على المدى الطويل سببها خلل في األوعية الدموية والجهاز العصبي. عدُ تُ دراسة من خالل القدم السكري برعاية طبية محترفة، وذلك لمنع تطورها في المراحل المتقدمة يمكن أن ينتهي إلى الغرغرينا وبتر القدم. وقد بدأت هذه ال ر مريض واحد منهم للتحقيق، هذا المريض ض لديهم مرض السكري ووجود انسدادت مختلفة في شريان أطرافهم السفلى.وقد تم اختيايمر اثني عشرمتابعة وجود تضيق متعدد في الشريان الفخذي السطحي.ارتكزت هذه الدراسة على تحليل الحالة الراهنة للمريض والتكهن بتقدم لديه تضيق في شريان باطن الركبة سير حدوث الغرغرينا في الطرف السفلي.تم الحصول على للشريان وتف شبه الكلياالنسداد الذي يحدث في الشريان الفخذي السطحي حتى يصل االنسداد ايين في القدم قياس القيم الهندسي للشرايين والتضيق مباشرة من المريض باستخدام جهاز تصوير األوعية. وقد تم التحقيق من مرض الغرغرينا و تضيق الشر ) تضيق من قطر الشريان ٪٩٠، ٪٧٥ة باستخدام أربعة نماذج مع (). وتعرض نتائج الدراسansys fluent cfdالسكري باستخدام برنامج محاكاة ( ذي األصلي في حالة المريض الصحية ومقارنتها مع الحالة الراهنة والصحية (بدون تضيق). وقد ظهر ذلك، مع وجود تضيق متعدد في الشريان الفخ ة الدم و إجهاد جدار القص في منطقة التضيق مقارنة مع المنطقة الخالية من السطحي للقدم السكري، وبافتراض الدم انه سائل نيوتوني، زيادة كبيرة في سرع ) م / ثانية في الشريان الصحي، ٠٬٨٨بلغت ذروة السرعة حوالي ( التضيق. وقد انخفض معدل تدفق الدم مقيدة بدرجة زيادة التضيق والعكس بالعكس. على التوالي. ٪٩٠, ٪٧٥) م / ثانية لنسب التضيق ٤٩٬٣١، ١٠٬٣٦وكانت قيم السرعة القصوى ((الحالة الحالية). ٪٤٢٬٤) م / ثانية لتضيق ٢وبلغت ( ، ٦٬٣٦مقابل قيم ( ٪٩٠) باسكال في تضيق ١٥٩١٦إلى ( ٪٧٥) باسكال في تضيق ١٠٩٤يتراوح إجهاد جدار القص األقصى في منطقة التضيق من ( على التوالي.الصحية، الحالة الراهنة الشريان) باسكال في ٣٨٠٬٥ svensk rapport mall al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 5161 (2015) experimental study of the thermal diffusivity and heat capacity concerning some duplex stainless steel riad harwill abdul abas * nabil kadhim taieh * * *avesta research centre/ high performance stainless and alloys/ avesta/ sweden **department of mechanical engineering/ technical institute/ kut *email: riad_riri@hotmail.com **email: nkadom123@gmail.com (received 20 october 2014; accepted 10 march 2015) abstract in the present work, thermal diffusivity and heat capacity measurements have been investigated in temperature range between rt and 1473 k for different duplex stainless steel supplied by outokumpu stainless ab, sweden. the purpose of this study is to get a reliable thermophysical data of these alloys and to study the effect of microstructure on the thermal diffusivity and heat capacity value. results show the ferrite content in the duplex stainless steel increased with temperature at equilibrium state. on the other hand, ferrite content increased with increasing cr/ni ratio and there is no significant effect of ferrite content on the thermal diffusivity value at room temperature. furthermore, the heat capacity of all samples increases with temperature from room temperature to 473 k, while it decreases with increasing temperature until 1073 k. then it increases with temperature at higher temperature. curie temperature and sigma phase formation temperature can be detected by heat capacity-temperature curves. keywords: duplex stainless steel, thermal diffusivity, thermal conductivity. 1. introduction modeling of high temperature process requires access to reliable thermophysical properties of high temperature systems that are relevant to heat and mass transfer computations. a priori estimations of the thermophysical properties have often been found to be limited to specific temperature and compositional ranges and it is still far away towards a unified picture of the structure of the system and its properties. experimental data are needed to satisfy the requirements of internal consistency and reliability with respect to extrapolations to temperature and compositional regions beyond the range of measurements. these in turn, would necessitate accurate experimental measurements under well controlled conditions and reliable property models that extrapolate the data as functions of temperature and composition [1]. the methods for measuring the thermal diffusivity can be classified into two main groups: viz. periodic and nonperiodic heat flow methods. the periodic method includes angstrom, thermoelectric and radial wave methods, while the nonperiodic method includes bar, small area, semi-infinite plate, radial heat flow high-intensity arc, electrically-heated rod and flash method. most of these methods have inherent limitations primarily due to heat transport via convection as well as heat loses by radiation at elevated temperatures. the impact of these factors is minimized by laser flash technique, which is one of the transient methods due to the small thickness of the sample and the high-speed heat supply to the specimen [2]. thermal conductivity assumes a critical role in the performance of materials in high temperature applications. low thermal conductivity values are required when the purpose is to minimize heat losses. on the other hand, when heat transfer from mailto:riad_riri@hotmail.com mailto:nkadom123@gmail.com riad harwill al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 5161 (2015) 52 one location to another is desirable, materials with higher thermal conductivities must be chosen. so, reliable thermal conductivity values are essential in a selection of a material in order to get the best performance of this material in a specific application. thermal conductivity is the property that determines the working temperature levels of a material, and it is an important parameter in problems involving steady state heat transfer (equation 1). however, it is one of the physical quantities whose measurement is very difficult and it requires high precision in the determination of the parameters involved in its calculation. ∆q ∆t.a = −k ∆t ∆x … (1) where; δq / δt a: rate of heat loss per unit area (wm -2 ). k: thermal conductivity (wk -1 m -1 ). δt / δx: temperature gradient (km -1 ). equation 1 is similar in form to fick’s first law for atomic diffusion. for these expressions, k is analogous to the diffusion coefficient d, and the temperature gradient parallels the concentration gradient, dc/dx [3]. measuring the thermal conductivity coefficient in the high temperature range is a complicated problem, because it is difficult to correctly include the heat transfer between sample and environment. in this situation, instead of measuring k, this coefficient may be found by result of measurements of the thermal diffusivity of the material (for which no measurement of heat flux required) and by the data of heat capacity 𝐶𝑝 and density using in the relation: 𝐾 = 𝐶𝑝.∝.𝜌 …(2) where: α=thermal diffusivity (m 2 /s); k=thermal conductivity (w/m k); 𝛒=bulk density (kg/m 3 ) and 𝐶𝑝 =specific heat (j/kg. k) [4]. the aim of the present work was to precisely measure the thermal diffusivity, heat capacity and thermal conductivity of some duplex stainless steel types made by outokumpu stainless company in sweden in order to get an accurate data of the thermophysical properties and to investigate the impact of microstructure and temperature on the thermophysical properties of these alloys. 2. experimental work all experimental works have been done at royal institute of technology, stockholm, sweden and at avesta research centre, avesta, sweden. 2.1. materials and samples preparation duplex stainless steels have a mixed microstructure of austenite and ferrite, the aim usually being to produce a 50/50 mix, although in commercial alloys the ratio may be 40/60. duplex steels have improved strength over austenitic stainless steels and also improved resistance to localized corrosion, particularly pitting, crevice corrosion and stress corrosion cracking. they are characterized by high chromium (19–28%) and molybdenum (up to 5%) and lower nickel contents than austenitic stainless steels. the most used duplex stainless steel are the 2205 (22% chromium, 5% nickel) and 2507 (25% chromium, 7% nickel); the 2507 is also known as "super duplex" due to its higher corrosion resistance. the properties of duplex stainless steels are achieved with overall lower alloy content than similarperforming super-austenitic grades, making their use cost-effective for many applications. five types of duplex stainless steel produced by outokumpu stainless ab, sweden have been used in the present work. table 1 presents the chemical compositions of the used materials. table 1, chemical composition of duplex stainless steel. sample chemicals composition (wt %) c n cr ni mo cu ti mn si co ldx, 2101 0.023 0.225 21.36 1.56 0.29 0.31 4.91 0.66 0.029 2304 0.02 0.115 23.3 4.8 0.45 0.3 2205 0.02 0.17 22.41 5.68 3.15 0.156 0.004 1.5 0.4 ldx, 2404 0.025 0.245 23.98 3.65 1.63 0.36 2.96 0.28 2507 0.02 0.27 25.07 6.91 3.82 0.22 0.83 0.23 riad harwill al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 5161 (2015) 53 eleven samples of duplex stainless steel (2205, 2205 (1000), 2205 (1100), ldx 2404, ldx 2404 (1000), ldx 2404 (1100), ldx 2101, ldx 2101 (1000), ldx 2101 (1100), 2507 and (2304) were used for thermal diffusivity measurements. (1000) and (1100) refer to the annealing temperature of the above mentioned samples in 10 minutes, while the other were non-heat treated samples. heat capacity measurements were done for as received samples only. 2.2. experimental techniques 2.2.1. laser flash technique a sinku-rico laser flash unit (model tc7000h/melt), with a maximum sample temperature limit of 1873 k used for the present thermal diffusivity measurements. a schematic diagram of the apparatus is presented in figure 1. the furnace heating elements, eight in number, are made of lanthanum chromate. the samples were heated under argon atmosphere at the rate of 6 k/min. the furnace temperature was measured using s-type (pt-10%rh/pt) thermocouple. in the laser flash method, top surface of a pellet shaped sample in about (2-3 mm) thickness is irradiated by a laser pulse which provides an instantaneous energy pulse. the laser energy is absorbed on the top surface of a sample and travels through the sample. the infrared detector (ir) monitors the temperature rise of the rear surface of the sample and the temperature vs. time profile is obtained as shown in figure 2. the thermal diffusivity is calculated from equation (3) [5]. ∝= 𝐴𝐿2 𝑡1/2 …(3) where a: constant=1.37/ π 2 , l: thickness of sample and t1/2 is the time required for the temperature of the rear surface to reach half of its maximum temperature. fig. 1. laser-flash unit schematic diagram[5]. fig. 2. a schematic illustration of sample set up and temperature vs. time profile of laser flash method [4]. riad harwill al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 5161 (2015) 54 2.2.2. differential scanning calorimetry (dsc) differential scanning calorimetry (dsc) is the most frequently used thermal analysis technique alongside tga, tma and dma. dsc is used to measure enthalpy changes due to changes in the physical and chemical properties of a material as a function of temperature or time. the method allows you to identify and characterize materials. an illustration of the netzsch sta 449c jupiter unit used in the present work is shown in figure 3. the apparatus was calibrated against in, sn, zn, ag and au. fusion temperature and heats of fusion were in agreement with the literature [6]. the dsc measurements was initiated by placing the small sample of 50 milligram in weight into an alumina crucible, along with the reference with similar size specification, on the platinum sample holder provided with the previously calibrated type s (pt-10%rh/pt) thermocouple . before the experiment was started, the furnace chamber was flushed with 99, 99999% purity argon gas. the dsc measurements were conducted in the temperature range of rt -1473 k with rate of 10 k /min in heating cycle [6]. fig. 3. schematic of netzsch 449c jupeter unit used in present work [6]. 2.2.3. scanning electronic microscope electron microscopes use electrons instead of light. in scanning electron microscopes of tungsten type as used in present work a wire of tungsten is heated to approximately 3073 k. at this temperature the electrons in the wire have such a high velocity that some of them leave the material by thermal emission. by applying electromagnetic fields these electrons can be controlled and used as an `` electron beam`` that can be directed on the sample of material that is to be investigated. interaction between this electron beam and the sample (or specimen) results in radiation being sent out that can be detected with a suitable detector as shown in figure 4. fig. 4. a schematic diagram of an sem [7]. 2.2.3.1. the energy dispersion spectroscopy detector (eds) eds is an analytical technique used for the elemental analysis or chemical characterization of a sample. it relies on an interaction of some source of x-ray excitation and a sample. its characterization capabilities are due in large part to the fundamental principle that each element has a unique atomic structure allowing unique set of peaks on its x-ray emission spectrum. to stimulate the emission of characteristic x-rays from a specimen, a high-energy beam of charged particles such as electrons or protons or a beam of x-rays, is focused into the sample being studied as shown in figure 4 [8]. microstructural investigations of all samples were carried out using scanning electron microscopy (sem) type (leo 440) in resolution of light microscope 2000 angstrom and resolution of scanning em 50 angstrom with wave length of http://en.wikipedia.org/wiki/chemical_element http://en.wikipedia.org/wiki/characterization_(materials_science) http://en.wikipedia.org/wiki/x-ray http://en.wikipedia.org/wiki/atom http://en.wikipedia.org/wiki/electron http://en.wikipedia.org/wiki/proton riad harwill al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 5161 (2015) 55 electrons 0.07 angstrom. furthermore, electron dispersion spectrometry (eds) attached to (sem) was used for chemical analysis of the phases. fig. 5. schematic of characteristic x-ray radiation [8]. 3. results 3.1 microstructural studies typical microstructures and chemical analyses of phases in duplex stainless steel are shown in figure 6 and table 2 respectively. austenite phase (light portion) is distributed as island in the matrix of ferrite (dark portion). it can be seen that the ferrite content increases with increasing annealing temperature of the most of the samples. 2205, α% =57.83 2205 (1000), α% =58.86 2205 (1100), α% =59.07 ldx 2404, α% =51.03 ldx 2404 (1000), α% =52.69 ldx 2404 (1100), α% =52.6 ldx 2101, α% =55.62 ldx 2101 (1000), α% =52.1 ldx 2101 (1100), α% =54.73 2304, α% =45.35 2507, α% =51.38 fig. 6. microstructures of duplex stainless steel. m = x 600. riad harwill al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 5161 (2015) 56 table 2, amount of alloying elements in the ferrite and austenite phases by using eds attached to sem. si cu mo ni cr n fe sample 0.52 1.45 22.11 70.89 α ldx 2101 0.45 1.78 20.7 71.1 γ 0.57 0.42 0.39 1.2 24.47 0.04 71.33 α ldx 2101 (1000) 0.47 0.45 0.2 1.99 21.9 0.51 72.92 γ 0.56 0.42 0.43 1.25 23.77 0.21 72.91 α ldx 2101 (1100) 0.53 0.46 0.29 2.01 22.18 0.58 72.68 γ 0.34 0.17 3.44 4.42 23.94 0.23 66.19 α 2205 0.31 0.16 2.22 6.77 21.52 0.38 67.3 γ 0.36 0.13 3.69 3.87 24.75 0.34 65.49 α 2205 (1000) 0.36 0.08 3.06 6.71 32.3 0.18 66.02 γ 0.35 0.17 3.3766 4.48 24.09 0.08 66.14 α ldx 2404 0.34 0.09 3.3266 5.27 23.82 0.1 66.8 γ 0.35 0.44 1.87 2.99 25.58 0.11 67.58 α ldx 2404 (1000) 0.27 0.51 1.14 4.03 24.01 0.63 68.12 γ 0.4 0.34 2.09 2.74 26.29 0.09 66.92 α ldx 2404 (1100) 0.31 0.53 1.26 4.53 24.39 0.42 67.27 γ 0.73 0.39 1.923 2.89 26.08 0.11 67.19 α 2304 0.29 0.59 1.246 4.38 24.17 0.45 67.66 γ 0.60 0.30 0.406 3.93 24.92 0.03 68.4 α 2507 0.55 0.44 0.31 6.14 21.8 0.43 69.36 γ 0.17 0.11 4.48 5.59 27.16 0.19 61.88 α ldx 2101 0.17 0.13 3.78 7.49 25.83 0.5 60.93 γ 3.2. thermal diffusivity measurements figure 7 shows the relation between the thermal diffusivity values and ferrite percentage of all samples at room temperature. it can be observed that is no significant effect of ferrite content in duplex stainless steel on the thermal diffusivity value at room temperature, which can be attributed to the amount of ferrite in samples are similar because the temperature of heat treatment at 1273 k and 1373 k does not show a significant changing in the phase fraction or composition of the alloys. the error bar in the thermal diffusivity measurements can be about 2-5% because of the convection effect during the measurements. fig . 7. effect of ferrite content on thermal diffusivity at room temperature. figure 8 shows the thermal diffusivity temperature curve for above mentioned samples. it can be seen that the thermal diffusivity increases with increasing temperature of all studied samples. riad harwill al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 5161 (2015) 57 400 600 800 1000 1200 1400 0,035 0,040 0,045 0,050 0,055 0,060 0,065 0,070 ldx 2101 ldx 2101 (1000) ldx 2101 (1100) 2205 2205 (1000) 2205 (1100) ldx 2404 ldx 2404 (1000) ldx 2404 (1100) 2304 2507 th er ma l d iffu siv ity , c m 2 /s temperature, k fig . 8. thermal diffusivitytemperature curves of the samples. 3.3. heat capacity measurements heat capacity as a function of temperature based upon dsc measurements is presented in figure 9 and table 3. it can be seen that the heat capacity increases with the temperature at low temperature and decreases at high temperature up to about 1100 k. furthermore, the peak can be seen at 773 k (curie temperature), which is the limit temperature of a ferromagnetic substance, loses its ferromagnetic properties and behaves as a paramagnetic substance. another peak can be recognized above 1100 k, which can be due to the sigma phase precipitation. sigma phase (σ) is one of the secondary phases that nucleate and grow after relatively long holding time during the heat treatment. the precipitation of σ phase can be represented by a eutectoid reaction (α → σ + γ2) where ferrite phase is transformed into σ phase, which is enriched in cr and mo, and γ2 phase (secondary austenite), which can be depleted in cr and mo. the nucleation of σ phase generally starts at the α/ γ boundaries and proceeds towards the ferrite phase until its complete transformation [9]. small amount of the samples and the small changing of chemical composition of the sample surface, leads to error bar about 3 to 5% of all heat capacity values. table 4 summarizes the measured thermophysical properties of the duplex stainless steel samples used in the present work at room temperature. fig. 9. heat capacitytemperature curves of the samples. riad harwill al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 5161 (2015) 58 table 3, heat capacitytemperature of the samples. cp, j/kg.k 373 k 473 k 573 k 673 k 773 k 873 k 973 k 1073 k 1173 k ldx, 2101 520 530 510 480 450 390 330 360 540 2205 520 530 490 440 390 390 420 420 520 ldx, 2404 500 520 490 450 440 400 340 290 290 2304 510 510 490 450 420 390 330 320 370 2507 480 490 440 390 360 290 260 190 220 table 4, thermophysical properties of the duplex stainless. sample thermal diffusivity, m 2 /s heat capacity, j/kg.k density, kg/m 3 thermal conductivity, w/m.k ldx, 2101 44. 10 -7 440 7.72 14.95 2205 41. 10 -7 480 7.70 15.15 ldx, 2404 41. 10 -7 400 7.72 12.66 2304 42. 10 -7 440 7.75 14.32 2507 43. 10 -7 400 7.83 14.81 4. discussion figure 10 shows the thermodynamic stabilities of the alloys under investigation at various temperatures were carried out with the help of thermo-calc software, which is a powerful software package for thermodynamic calculations. it is widely used for a variety of calculations including calculating stable and meta-stable heterogeneous phase equilibria, amounts of phases and their compositions, thermochemical data such as enthalpies, heat capacity and activities, transformation temperatures such as liquidus and solidus, driving force for phase transformations and phase diagrams (binary, ternary and multicomponent [10,11]. figure 6 and table 2 shows that is no significant increasing of ferrite content, when the heating temperature increased from 1273 to 1373 k. these results have a disagreement with the thermal calculation curves calculated using termo-calc software. it can be due to the measured values could not be reached the equilibrium state as calculated values using thermo-calc software. on the other hand, it can be seen that the thermal diffusivity is nearly constant up to 773 k as shown in figure 8. beyond that, there was an increase of the thermal diffusivity values. in general, the increase of the slope of the curves can be due to increase in the portion of the ferrite in the structure, as shown in figure 10 also. furthermore, the heat capacity increases with increasing temperature at low temperature and decreases at higher temperature. the peak at about 773 k refers to curie temperature of the samples as shown in figure 6. at high temperature the increasing of heat capacity with temperature can be due to increase ferrite portion in the structure. sigma phase forming can be recognized in the curves at about 1023 k for ldx 2404 and 2507 duplex stainless steel samples. if a ferromagnetic transition exists in a metal, thermal diffusivity always decreases from room temperature to the curie temperature, as the disorder increases. riad harwill al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 5161 (2015) 59 fig. 10. thermo-calc results of alloys. riad harwill al-khwarizmi engineering journal, vol. 11, no. 2, p.p. 5161 (2015) 60 5. conclusions 1. the ferrite content in the duplex stainless steel increased with temperature at equilibrium state. while in present study the equilibrium state could not be reached and there is no significant change at 1273 and 1373 k. 2. there is no significant effect of ferrite content in duplex on the thermal diffusivity value at room temperature. 3. there is no significant increasing of thermal diffusivity of the samples up to 773 k. beyond that there is an increasing of thermal diffusivity with the temperature. 4. heat capacity of all samples increases with temperature from room temperature to 473 k, while it decreases with increasing temperature until 1073 k. then it increases with temperature at higher temperature. 5. curie temperature and sigma phase formation temperature can be detected from heat capacitytemperature curves. acknowledgment the authors acknowledge the support received from the avesta research centre and royal institute of technology, stockholm, sweden for carrying out the present investigation. 6. references [1] s. seetharaman, du. sichen, r. eriksson, e. kapilashrami, high temperature materials and processes. volume 22, issue 5-6, pp. 283– 290. [2] r. abdul abas, m. hayashi, s. seetharaman, thermal diffusivity measurements of some industrially important alloys by a laser flash method, int. j. mat. res. ( zeitschri fur metallkunde) 2007, vol. 98, pp. 535-540. [3] w. d. callester, material science and engineering, chapter 17, pp.720. [4] s.v. stankus, i.v. savchenko, a.v. baginiskii, o.i. verba, a.m. prokop and a. khairulin, high temperature, 2008, volume 46, no 5, pp. 731-733. [5] t. matsushita and s. seetharaman, high temperature process theory (mh2453), division of materials process science, 200907-01 [6] netzsch instrument, thermal analysis software, proteus, for ms windows, ver 4.2, aldridge, west midlands uk, (2003). [7] j.goldstein, scanning electron microscope and x-ray microanalysis. third edition ed. 2003. [8] joseph goldstein (2003). scanning electron microscopy and x-ray microanalysis. springer. isbn 978-0-306-47292-3. [9] e. bettini1 et al, int. j. electrochem. sci., 9 (2014) 61 – 80. [10] j-o. andersson, t. helander, l. höglund, p. shi, b. sundman: elsevier science ltd, thermo-calc & dictra, computational tools for materials science calphad, 26 (2002), 273. [11] a. rudajevova and j. burianek, journal of phase equilibria vol. 22, no.5, 2001. pp. 560-563. http://books.google.com/books?id=ruf9dqxcdlqc http://books.google.com/books?id=ruf9dqxcdlqc http://en.wikipedia.org/wiki/international_standard_book_number http://en.wikipedia.org/wiki/special:booksources/978-0-306-47292-3 (2015) 5161، صفحة 2، العذد11دالخىارزهي الهنذسية الوجلجلة مرياض هرول عباش 61 بالفىالر الوقاوم للصذأ الوسدوجدراسة تجريبية لألنتشارية الحرارية و السعة الحرارية الوتعلقة **نبيل كاظن تايه * رياض هرول عبذ العباش اىغ٘ٝذ /ٍشمض بح٘د افٞغخا* م٘ث / اىَعٖذ اىخقْٜ ** riad_riri@hotmail.com ّٜٗاىبشٝذ االىنخش: * nkadom123@gmail.com :االىنخشّٜٗ اىبشٝذ ** الخالصة ىَجٖض ٍِ ششمت حٌ فٜ ٕزا اىبحذ قٞاط األّخشاسٝت اىحشاسٝت ٗ اىغعت اىحشاسٝت عيٚ عْٞاث ىَجَ٘عت ٍخخيفت ٍِ عبائل اىف٘الر اىَقاًٗ ىيصذأ اىَضدٗج ٗ ا أُ اىٖذف k 1473.أٗح٘مٍ٘ب٘ اىغ٘ٝذٝت ٗحَج اىخجاسب عيٚ ٕزٓ اىعْٞاث ضَِ ٍذٙ ٍِ دسجاث اىحشاسة حشاٗحج بِٞ دسجت حشاسة اىغشفت ٗ دسجت حشاسة ىقذ أظٖشث اىْخائج أُ ٍحخ٘ٙ اىفشاٝج فٜ عبائل . ئل ٍِ حٞذ خ٘اصٖا اىفٞضٝ٘حشاسٝت ٍِ ٕزٓ اىذساعت ٕ٘ اىحص٘ه عيٚ بٞاّاث ٍعخَذة ٍٗ٘ر٘قت ىٖزٓ اىغبا ٍحخ٘ٙ اىفشاٝج ٝضداد مزىل ٍع أصدٝاد ّغبت ٍِٗ ّاحٞت أخشٙ أُ, اىف٘الر اىَقاًٗ ىيصذأ اىَضدٗج ٝضداد ٍع أصدٝاد دسجت اىحشاسة فٜ حاىت اىخ٘اصُ اىحشاسٛ اسٝت عْذ دسجت حشاسة اىنشًٗ اىٚ اىْٞنو ٗقذ بْٞج اىْخائج أٝضا أّ ىٞظ ْٕاك أٛ حارٞش ٗاضح ىَحخ٘ٙ اىفشاٝج فٜ اىف٘الر اىَضدٗج عيٚ قَٞت األّخشاسٝت اىحش حخْاقص عْذ أسحفاع ٗ, (k 473ٍِ دسجت حشاسة اىغشفت حخٚ ) سجت اىحشاسة اىغشفت ٗعالٗٓ عيٚ رىل أُ اىغعت اىحشاسٝت ىجَٞع اىعْٞاث حضداد ٍع صٝادة د مَا َٝنِ اعخخذاً ّخائج فح٘صاث اىغعت اىحشاسٝت ىخحذٝذ دس جت حشاسة مٞ٘سٛ ٗ . ٗبعذ رىل حضداد ٍع اصدٝاد دسجت اىحشاسة, k 1073دسجت اىحشاسة ىغاٝت . ىَقاًٗ ىيصذأ دسجت حشاسة ّش٘ء ط٘س عٞنَا ىٖزا اىْ٘ع ٍِ اىف٘الر ا mailto:riad_riri@hotmail.com mailto:nkadom123@gmail.comالبريد mailto:nkadom123@gmail.comالبريد al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 4, no. 2, pp 4658 (2008) optimum design of stiffened plate-structure subjected to static loading dr. hatem h. al-taee dr. adil a. al-moosawy mohammed a. al-shojary university of babel / college of engineering/ departement of mechanical engineering (received 4 march 2007; accepted 2 january 2008) abstract the field of structural optimization (optimal design) has grown rapidly over the past decades with many different optimization methods that could be used to produce a structure of minimum weight. this research deals with two aspects, in the first, a general numerical technique based on the finite element analysis and it suggests to investigate the preliminary behavior of metal stiffened plate under action of static load environment. the technique was included a finite element model of the structures using highorder isoparimetric plate elements to be used to create a certain models to obtain their optimum design. the models are characterized such that, each model is builded using different types of stiffener configuration. the second aspect was concerned with the investigation of the optimum design configuration of the structures. the optimization techniques used is called morphing evolutionary structural optimization (meso). the morphing eso was examined in this research to be applied on stiffened plate structures. the morphing eso is based on the simple concept that by slowly removing efficient material from a structure, the residual shape evolves in the direction of making the structure better. the mathematical representation of this method is accomplished in this thesis with full programming and modification required being applicable to a new structure with a new condition. where the thickness of the plate and stiffeners, and the stiffener height are the design variable. while the objective of the optimization is the structure weight and inequality constraints are the maximum von misses stress required for each structure. keywords: static analysis, bending , evolutionary structural optimization, stiffened plate, ansys. introduction: structural optimization has received ever increasing in civil, chemical and especially aeronautical engineering with the advent of high speed computers; the tools of structural optimization are no longer resituated to the classical differential calculus and variation calculus. indeed, various numerical search techniques have been developed over the past three decades. the optimization problem is classified on the basis of nature of equations with respect to design variables. if the objective function and the constraints involving the design variable are linear then the optimization is termed as linear optimization problem. if even one of them is nonlinear it is classified as the non-linear optimization problem. in general the design variables are real but some times they could be integers for example, number of layers, orientation angle, etc. the behavior constraints could be equality constraints or inequality constraints depending on the nature of the problem. the structural optimization problem can be posed as: minimize or maximize f = f(x1, x2, x3,……., xn) subject to: c1=c1 (x1, x2, x3,…....,xn) c2=c2 (x1, x2, x3,…….,xn) ...(1) cn=cn (x1, x2, x3,…….,xn) and  1=  1(x1, x2, x3,…...….…,xn)  0  2=  2(x1, x2, x3,……….... ,xn)  0 ...(2) hatem h. al-taee al-khwarizmi engineering journal, vol. 4, no. 2, pp 46-58 (2008) 47  n=  n(x1, x2, x3,…..….....,xn)  0 x1,x2,x3,…,xn are the design variables ,c1,c2, ,….,cn are equality constraints and  1,  2,….., n are inequality constraints. the nature of the mathematical programming problem depends on the functional form of f, c, and , if these are linear function of design variables, and then the mathematical programming problem is treated as linear programming problem. on the other hand if any one of them is a nonlinear function of the design variable, then it is classified as nonlinear programming problem. there are three main classes of structural optimization problems depending on the type of the design variables used: sizing, shape, and topology. in sizing optimization problems, the aim is usually to minimize the weight of the structure under certain behavioral constraints on stresses and displacements. the design variables are most frequently chosen to be dimensions of the cross-sectional area of the members of the structure. in structural shape optimization problems, the aim is to improve the performance of the structure by modifying its shape. the design variables are either some of coordinates of the key points in the boundary of the structure or some other parameters that influence the shape of the structure. structural topology optimization assists the designer to define the type of structure that is best suited to satisfy the operating conditions for the problem at hand. during the past three decades, many numerical methods have been developed meet the demands of structural design optimization. these methods can be classified in two general categories [1]: 1. deterministic (gradient based method). 2. probabilistic (heuristic based method). the research work dealing with the optimum design of stiffened plate structures is an issue that has not yet been addressed adequately by the scientific community. haftka, r. t [2] solved a material topology optimization problem where the design model is adapted during the optimization process. marcelin et al [3] determined optimum hat-stiffened compression panel designs by using a structural synthesis technique. effects of simplifying assumptions made in the bending analysis for the optimization program are investigated using a more accurate analysis, which is a linked plate element program. optimization results for an aluminum panel are compared with available results. optimization results for hatstiffened graphite-epoxy panels show a 50-persent weight savings over optimized aluminum panels. using the structural synthesis technique, composite panels are shown to posses a variety of proportions at nearly constant weight. patnaik. and sannaran. [4] presented the optimum design of stiffened cylindrical panels weight as the objective function and constraints or the frequencies in the presence of initial stresses by using unconstrained minimization techniques of mathematical programming problem. the interaction between the buckling constraints and the frequency constraints in the presence of initial stresses is inclined in the following. loss of load carrying capacity due to imperfection and due to suddenly applied load is included in the buckling analysis. ding,y.[5] treated with finite element analysis and the optimization problem of sandwich construction. the thickness of the faceplates and the core are used as design variables. in 1992, a new method of structural optimization was developed by (xie and steven.,1998) [1] called the evolutionary structural optimization (eso) method. evolutionary structural optimization (eso) is a design method based on the simple concept of gradually removing inefficient material from a structure as it is being designed. through this method, the resulting structure will evolve toward its optimum shape. an engineer must specify the design domain and loads and kinematics constrains. the past research has shown that the eso method could be successfully applied to all types of elements, i.e. beam, plates and bricks, structural with multiple load cases, to structural dynamic problem and to structure with non-linear properties. however, the eso method so far, does not allow to incorporate any nonstructural constraints to be incorporated during its process [6]. the initial stages of development of the eso method were employed in verifying the classical single load problems to demonstrate its applicability. once the method had been shown to work accurately and efficiently [7], it was then extended to structures with multiply load cases. 2. analysis of stiffened structures: the use of stiffened structural elements in most branches of structural engineering began in the nineteenth century with the application of steel flat or curved plates for hulls of ships and subsequently with the development of steel bridges and aircraft structures and other situations where the reduction of self-weight is an important design objective for satisfying the requirements of increased stiffness and reduced weight. stiffened plate and cylindrical structures have found widespread in a variety of engineering hatem h. al-taee al-khwarizmi engineering journal, vol. 4, no. 2, pp 46-58 (2008) 48 structures such as steel chimneys, pipes and conduits, missile bodies, side shells of ships, its deck and superstructures, submarines and offshore structures because it can achieve economy in weight with no sacrifice of strength. stiffened cylindrical structure are very common in engineering practice because they combine high stiffening characteristic with low material volume [7]. plates stiffened by longitudinal and transverse members are one of the most common structural components. use of stiffeners makes it possible to resist highly directional loads, and to introduce multiple load paths that many provide protection against damage and crack growth under both compressive and tensile loads. the biggest advantage of the stiffeners though, is the increased bending stiffness of the panel with a minimum of additional material. stiffened plates have been considered for used in these weight-sensitive structures, where high strength-to-weight and stiffness-to-weight ratios are required. besides their high strength and stiffness, stiffened plates are usually thin. thus, bending is a critical consideration for the optimum design of structures made of such plates. these plates are fabricated as an assembly of individual plates. this allows the designer to select the most effective disposition of material in the cross section to carry the specified loading. figure (1) shows types of honeycomb core. 2.1. stress-strain relation-ship: the stressstrain relations in coordinates aligned with principle material directions are given by:[3].                                                              yz xz xy z y x yz xz xy z y x c c c c cc cc             66 55 44 33 2221 1211 00000 00000 00000 00000 0000 0000 ...(3) from the usual thin plate assumption, the normal stress z is assumed small enough to be neglected and the corresponding z is eliminated (plane stress problem is assumed) [8]. therefore, the equation (3) becomes:                                                      yz xz xy y x yz xz xy y x c c c cc cc           66 55 44 2221 1211 0000 0000 0000 000 000 ...(4) or      e where: c11=c22=(1- )/a, c12=c21=( )/a, c44=g, c55=fg, c66=fg, a= e )21)(1(   , g= )1(2  e where f is the shear factor for homogeneous plate should be given a value of 1.2 in order to account for the fact that the transverse shearing stresses produce too little strain energy [6]. 2.2. element parameters: all above finite element models have been created using linear fournode quadrilateral plane elements. this type of elements is used for plate and shell structures for both membrane and flexure load conditions. in this section, the parameters that are concerned with the selected element are discussed. these parameters are basically included; the element property parameters include the material properties and the thickness of the element at each node. for the rectangularhoneycomb finite element models, the material properties for all elements are specified as isotropic material. the ration of thickness value to the smallest element dimension must be equal or less than (0.1) in order to maintain the element to be thin [3]. the element degrees of freedom are assigned at each node along the element coordinate system figure (2) shows the element degrees of freedom of any point located on the element is function of that of all element nodes ,as:-. fig. 1. types of honeycomb core. hatem h. al-taee al-khwarizmi engineering journal, vol. 4, no. 2, pp 46-58 (2008) 49                                   4 1 4 1 0 ),(),( ),( ),( ),( i yi xi i i i i i i nz w v u n w v u       …(5) where: z = 2 t 2 t  ni=shape functions. z = nodal thickness ui , vi , wi= global nodal displacements.  xi ,  yi = global nodal notations it is obvious that each node has five degrees of freedom, and then the element is of twenty degrees of freedom. not all but some of the element degrees of freedom are considered at each of the finite element models, depending upon the function (boundary conditions) of that model. 2.3. static analysis static analysis is achieved on each of the finite element models for each function with their corresponding boundary conditions and load sets. static analysis solution has been included the calculation of the effects of the applied static distributed loads on each model for each function with the corresponding boundary conditions. these effects included displacements, strains, and stresses that are induced in the structure due to the applied loads. the static analysis is governed by the following equilibrium equations (in matrix notation): [k].{u}={f} ...(6) where: [k]=  n e 1 [k]e :the assembled stiffness matrix. and        ddjbebk t a e      1 1 1 1 t da [e][b][b] ...(7)        1 1 1 1a t dd ]][[][[p]da[b] jpenf t e …(8) ansys package solve the above equilibrium equations to obtain the following results: displacements of each node along their free degrees of freedom. strains, and stresses at each element along element coordinate axis. von misses stresses and the maximum shear stresses. 3. morphing evolutionary optimization in this section the work presented deals with the morphing evolutionary structural optimization (meso) method. the morphing eso method lies somewhere between a heuristic and a gradient based optimization method. this means that meso can search through the structural domain, locating both local and global minimal [2]. because of its evolutionary characteristics, it does not stop when an apparent minimum has been located; instead, the evolution process continues to evolve the structure in search for a better one. compared with eso, instead of removing an element totally, morphing eso can remove the element gradually. the reason for this was that when an element satisfied the eso inequality constraints, instead of removing it, it was change to another element of either less strength, thickness or smaller density, thus morphing that element instead of removing it. 3.1 morphing eso procedure: the principles and procedure that define morphing eso are as follows [8]. 1set up a dense finite element mesh that fully covers the maximum design domain of the structure. 2apply all kinematics boundary constraints, loads, materials, element properties, etc. 3specify the criteria used to optimize the structure, for example von mises stress required. 4specify the eso driving parameter, for example the maximum, or mean von mises stress of the structural domain. 5define a set of allowable discrete volumes in decreasing order of the strength that each original element of the structure is made. the discrete set could be a set of plate thickness, modulus of elasticity or density or others. this set could be written in the following: xe= {a1, a2, a3, a4,.., an} …(9) fig. 2. the element degrees of freedom. x θ yθ hatem h. al-taee al-khwarizmi engineering journal, vol. 4, no. 2, pp 46-58 (2008) 50 or xe= {t1, t2, t3, t4, .., tn} …(10) or xe={e1, e2, e3, e4, .., en} ...(11) where: a is the beam cross sectional area with a1>a2>a3>an. e is the material modulus of elasticity e1>e2>e3>en. t is the material thickness with t1>t2>t3>tn 6. carry out a linear static finite element analysis of structure. 7using the following eso inequality, determine if there are any elements in the structure that satisfies it. if an element satisfies this equation, the elements discrete value which is allowed to the next discrete value in the set. since the set is arranged in decreasing order of strength, this new value will be weaker than the one it replaces. evm , rr* maxvm , ...(12) where: evm , =von misses stress or selected criterion of element e. maxvm ,  =maximum von misses stress or selected criterion of the structure. and: rr=rejection ratio, used to control the element removal process. rr=ao+a1*ss+a2*ss 2 +a3*ss 3 ...(13) where: ss steady state number. (equal to the iteration number) 0rr 1 ao,a1 are coefficients, determined from experience with morphing eso method, usually the first two forms are considered. this can be explained in the following fashion. if at iteration k, the element eth has a discrete value x k ei , then in iteration k+1, if the equation above is satisfied, the discrete value of element becomes x k ei 1 1   where: x k ei > x k ei 1 1   e is the element. i is the i th position in the discrete set. k is the k th iteration in the evolution cycle. x k ei : is the discrete value i of element e in iteration k. 7if a state is reached where no element of the structure satisfies the above equation a steady state and local optimum has been reached. the steady state number is then incremented by (1) and steps (7) and (8) are repeated. 8step(6) through (9) are repeated until the minimum value of the performance index is reached, or until the desired minimum volume or weight of the structure has been reached. 3.2. mathematical representation of the morphing from the description of the morphing eso method, it can be seen that morphing is a discrete optimization problem similar to the classic eso definition, but with a discrete set of variables instead of the {0,1} binary set of classic eso [6]. the mathematical representation for morphing eso is as follow: minimize f(x)=pi= fl n e ee v 1 . ...(14) subject to, ye (ye* vme  -rr* maxvm  )  0 ...(15) xe={d1,d2,d3,…..,di,di+1,…..,dn} ...(16) yeye={1, d i id 1 } where: pi is performance index (substantial number of optimization methods available for designer /engineer to use as an aid to the design of the structure). e is the element. xe is the set of allowable elements in the structure. n is the number of elements in the structure. di is the discrete value at location i in the set. ye is the morphing multiplier where di > di+1. ye is the set of morphing multiplier values. initially the inequality constraint has a morphing multiplier magnitude of 1. however, if the stresses in the element cause the constraint to be violated, the second morphing multiplier is selected and the discrete value of the element is changed to the value di+1. although by doing this the inequality constraint may remain violated, the morphing multiplier will reduce the amount of the violation. carrying out another finite element analysis will reveal the true effect of the discrete value change and the amount by which the inequality criterion is now violated. hatem h. al-taee al-khwarizmi engineering journal, vol. 4, no. 2, pp 46-58 (2008) 51 4. results and discussion: optimization results for stiffened plate are presented in this section. the plate material is aluminum which is assumed as an isotropic material. the properties are shown in table (1) [4]. table 1 properties of material. material aluminum young's modulus(e) 70.3 gpa poisson's ratio( ) 0.33 density 2712.64 kg/m3 4.1 flat plate structure: the optimal model of flat plate with all kinematics boundary conditions is presented. the plate is exposed to uniformly distributed load [see appendix]. since the structure is required to optimize. therefore, the morphing evolutionary structural optimization is used to carry out the optimization of this structural. total number of elements are ninety six (8*12) elements, each side element is square of dimension (5*5) cm 2 . the length of the flat plate is 60 cm and the width is 40 cm shown in fig.3. thickness of element was proposed to be the design variable of this model. initially for each element the thickness is set the maximum value (6.5mm). von misses criterion was used as an optimization criterion while the maximum von misses criterion was used as driving criterion. the ansys package is used to do the analysis of the structure. for each element if the optimization criterion is satisfied, the thickness of each element is set in to the lower value using morphing evolutionary structural optimization. the objective of the optimization is the structure weight and the inequality constraints are the maximum von misses stress required in this structure. the evolution process starts with initial rejection ratio rro=0% and evolutionary rate er=0.25%.the stress distribution (von misses contour) for each element at steady number ss=0 (no optimization is performed). the mean value of stress about 116.32 n/mm 2 and the maximum value about 232 n/mm 2 shown in fig. (4). the performance index (pi) versus steady state number is plotted as in fig.(5). the weight index (w/wo) is plotted versus the steady state number as shown in fig (6). from fig.(5) shown that the best set are no.43 where the minimum value of performance index (pi=2.09) and weight index (w/wo)= 76.3% from fig.(6). the stress distribution versus steady state number for mean and maximum von misses stress is shown in fig.(7). it is shown that the mean stress is increased with increasing the steady state number but the maximum stress is still with the same range. figure (8) show that the von misses contour for this steady state (no.43).it is shown that the maximum von misses stress is(234 n/mm 2 ), and the mean von misses stress is (153.67 n/mm 2 ). fig. 3. flat plate finite element model. fig. 4. element von mises contour at ss=0. fig. 5. performance index versus steady state number. 0 20 40 60 80 100 steady state number(ss) 2.0 2.2 2.4 2.6 2.8 3.0 p e rf o rm a n c e i n d e x (p i) performance index pi hatem h. al-taee al-khwarizmi engineering journal, vol. 4, no. 2, pp 46-58 (2008) 52 the von misses stress distribution for the flat plate is illustrated in fig. (9). it is note that the maximum von misses stress occurs at the distances of 0-15% from the plate constraint because of bending moment. it is notice the maximum thickness occurs at the element closed to the plate root due to the maximum von misses stress, and decreasing along the length of plate in the direction of the tip in which a minimum thickness is attained. 4.2 rectangular-honeycomb structures: the same load, material properties and dimensions for flat plates are applied in the optimal design of rectangularhoneycomb plate structures. the objective of the optimization is the structure weight and the inequality constraints are the maximum von misses stresses required in this structure. initially the thickness of the skin plate is (2mm) and the thickness of stiffeners is (4mm), and the height of the stiffeners is (5cm). the structure at the initial stage where no optimization occur (ss=0) have maximum von misses stress of (165.09 n/mm 2 ), and the mean von misses stress is (73.68 n/mm 2 ) shown in fig. (10).the performance index (pi) versus steady state number is plotted as in fig.(11). the weight index (w/wo) is plotted versus the steady state number as shown in fig. (12). fig. 6. weight index versus steady state number. 0 20 40 60 80 100 steady state number(ss) 60 80 100 120 w ei g h t in d ex (w /w o )% weight index (w/wo)% fig. 7. element von mises contour versus steady state number. 0 20 40 60 80 100 steady state number(ss) 80.00 120.00 160.00 200.00 240.00 280.00 v o n m is e s s tr e s s (n /m m ^ 2 ) von mises max mean fig. 8. best topology (von mises) contour. fig. 9. distribution of von mises stress on the finite element model. 0.00 0.20 0.40 0.60 0.80 1.00 z/l 100.00 150.00 200.00 250.00 v o n m is e s s tr es s (n /m ^ 2) location at line 1 line 2 line 3 line 4 line 5 fig. 10. element von mises contour at ss=0. hatem h. al-taee al-khwarizmi engineering journal, vol. 4, no. 2, pp 46-58 (2008) 53 von misses stress distribution for the rectangular-honeycomb model is shown in fig.(13). it is noted that the maximum von misses stress occurs at the root of the plate because of maximum bending moment. so that the location of maximum von misses stresses will be of maximum thickness value and the same for minimum von misses stresses that occur at the tip and attain a minimum thickness values. the von misses stress distribution for the flat plate is illustrated in fig. (15). figure (16) shows that the weight index for stiffeners versus the steady state number (ss) from this figure show that the removing material from stiffener no.1 is greater than the other stiffeners, while the stiffener no.5 is less than the other stiffeners because higher von misses stress at the stiffener no.5, in the other word the lower von misses stress at the stiffener no.1. fig. 11. performance index versus steady state number. 0 20 40 60 80 100 steady state number(ss) 2.4 2.6 2.8 3.0 pe rf or m an ce in de x( p i) performance index(pi) pi fig. 12. weight index versus steady state number. 0 20 40 60 80 100 steady state number(ss) 20 40 60 80 100 120 w ei g h t in d ex (w /w o ) weight index w/wo fig. 13. element von mises contour versus steady state number. 0 20 40 60 80 100 steady state number(ss) 40 80 120 160 200 v o n m is e s s tr e s s (n /m m ^ 2 ) von mises stress max mean fig. 14. best topology (von mises) contour. 0.00 0.20 0.40 0.60 0.80 1.00 z/l 40.00 80.00 120.00 160.00 200.00 v o n m is e s s tr e s s (n /m ^ 2 ) location at spar 1 spar 2 spar 3 spar 4 spar 5 fig. 15. distribution of von mises stress on the finite element model. fig. 16. weight index versus steady state number (ss) for spars. 0 20 40 60 80 100 steady state number(ss) 40 60 80 100 120 w ei g h t in d ex (w /w o ) location at spar 1 spar 2 spar 3 spar 4 spar 5 hatem h. al-taee al-khwarizmi engineering journal, vol. 4, no. 2, pp 46-58 (2008) 54 4.3 diagonal-honeycomb structures: replacing the longitudinal and transverse stiffeners by the diagonal stiffeners and the same loads and material properties of rectangularhoneycomb model, the diagonalhoneycomb model is presented. the design variable in this structure was the thickness of each element in the skin plate structure, and the thickness of the diagonal stiffeners structural. while the objective of the optimization in the structure are the weight and the inequality constraints are the maximum von misses stress required in this structure. initially the thickness of the skin plate is (2.5mm) and the thickness of the stiffeners is (4.5mm) and the height of the stiffeners is (5 cm). at the initial stage for steady state number ss=0 (no optimization is performed), the value of mean stress about 72.8 n/mm 2 and the maximum value about 189 n/mm 2 as shown in fig.17. figure (18) shown that the performance index (pi) versus the steady state number (ss). figure (19) shown that the weight index (w/wo) versus the steady state number (ss). the maximum and mean element von misses stress is plotted versus the steady state number (ss) for the set 0 to 45 as shown in fig. (20), from this figure shown the mean stress is increased with increasing the steady state number but the maximum stress is still with the same range. 4.4 comparison of results with theoretical study 4.4.1 michell type structure with fixed supports michell type structure was modeled and optimized using 2d-plane plate element as shown in fig. (21). the force applied was 200 n in the centre of the structure. the mesh used was 40*20 plate elements. the problem had been solved by (ostwald, m.1996) [7], using intelligent cavity creation algorithm. the maximum von misses stress was as the eso driving criterion. the rejection ratio was a1=0.01. the optimal design is displayed in fig. (22). table (2) presented the weight index and performance index. there are fig. 17. element von mises contourat ss=0. fig. 18. performance index versus steady state number. 0 20 40 60 80 100 steady state number(ss) 2.4 2.8 3.2 3.6 4.0 p er fo rm an ce in de x( p i) performance index(pi) (pi) fig. 19. weight index versus steady state number. 0 20 40 60 80 100 steady state number(ss) 20 40 60 80 100 120 w ei gh t i nd ex (w /w o) weight index w/wo fig. 20. element von mises contour versus steady state number. 0 20 40 60 80 100 steady state number(ss) 40 80 120 160 200 240 v o n m is s e s s tr es s (n /m m ^2 ) von misses stress max mean hatem h. al-taee al-khwarizmi engineering journal, vol. 4, no. 2, pp 46-58 (2008) 55 good agreements with the results shown in table (2) for michell structure with fixed supports. table 2 comparison of results with theoretical study weight index performance index ostwald, m. 52.36% 2.528 present work 49.68% 2.542 4.5 effect of height of stiffeners 4.5.1 rectangular-honeycomb structures when the minimum thickness (ts=1.37mm) is constant for each element of the stiffeners, and change the height of the stiffeners to obtain the optimal case of rectangular-honeycomb models. table (3) shown that the effect of the stiffeners. it is shown that optimal design occur at h=6.09 cm with max)von  =183.365, pi=2.56 and uz=3.897 mm. table 3 effect of the height of stiffeners. volume (102m3) deflection (mm) )max vom  (mpa) h (cm) 4.852 4.55 176.67 5.0 4.264 6.31 276.23 5.0 4.358 5.644 252.25 5.2 4.452 5.1292 236.16 5.4 4.546 4.656 216.38 5.6 4.642 4.244 193.64 5.8 4.734 3.897 173.365 6.09 4.5.2 diagonal-honeycomb structures table (4) shown that the effect of height of stiffeners on the diagonalhoneycomb models, at (ts=1.461 mm) constant for each element of the stiffeners. it is shown that the optimal case occurs at h=6.19cm. at this height the von misses stress is (191.36 n/mm2), pi= 2.79, and normal deflection (uz=4.4625 mm). table 4 effect of the height of stiffeners. volume (10-2m3) deflection (mm) )max vom  (mpa) h (cm) 5.944 4.732 202.59 5.0 5.568 7.295 302.35 5.0 5.651 6.525 282.16 5.2 5.675 5.621 250.78 5.4 5.729 5.152 233.46 5.6 5.783 4.813 217.37 5.8 5.837 4.646 207.43 6.0 5.891 4.462 191.36 6.19 5. conclusions the optimum design of a general stiffened plate structure by morphing evolutionary structure optimization method can be obtained. so any parameter of the stiffened plate can set it in to the best value with easy procedure. when using the morphing eso method with isotropic stiffened plate, the optimization by morphing eso is able to produce a very good smooth plate thickness variation. the difference between the upper and lower bound of the applied stresses is decreased in to a minimum value using this method. the ratio of the stiffness/weight is increased in to the maximum value using this method. from the results a design optimization for rectangular-honeycomb plate structure gives the best result than the other models. 100 100 200 200n line of symetry fig. 21. design model for michell structure with fixed supports. fig. 22. optimal topology for michell structure with fixed supports at ss=64. 100 100 200 200n line of symetry material: aluminum e: 69e+9 n/m2  : 0.35  : 2700 kg/m3 100 100 200 200n line of symetry material: aluminum e: 69e+9 n/m2  : 0.35  : 2700 kg/m3 hatem h. al-taee al-khwarizmi engineering journal, vol. 4, no. 2, pp 46-58 (2008) 56 nomenclature: a cross section area e elasticity modulus of isotropic material {f} overall load vector g shear ( rigidity ) modulus of isotropic material hs height of stiffeners [k] element stiffness matrix ls side length of rectangular or diagonal cell ni(  , ) shape function at node i pi performance index rr rejection ratio s.f safety factor ss steady state number {f} overall load vector g shear ( rigidity ) modulus of isotropic material t thickness tp thickness of plate ts thickness of stiffeners x,y,z global coordinate system axis x,y,z nodal coordinate system axis ui linear displacement along element xaxis vi linear displacement along element yaxis i normal stress in i-direction i normal strain in i-direction ij shear stress component through ijplane v poisson’s ratio of isotropic material  , intrinsic coordinate system appendix applied load for plate structure: load will be applied on nodes (as nodal force). nodal force that corresponding to each node is illustrated in table (6). force (n) force type node number force (n) force type node numbe r force (n) force type node numbe r -63.52 fy 32 -47.642 fz 51 -31.762 fz 4 -63.52 fz 32 -63.525 fz 65 -42.35 fz 6 -84.7 fy 30 -79.406 fz 79 -52.935 fz 8 -84.7 fz 30 -95.287 fz 93 -63.52 fz 10 -105.8 fy 28 -111.16 fz 107 -74.11 fz 12 -105.8 fz 28 -127.05 fz 18 -84.7 fz 2 -127.0 fy 26 127.05 fx 18 84.7 fx 2 -127.0 fz 26 -55.584 fz 53 -39.702 fz 49 -148.2 fy 24 -74.112 fz 67 -52.937 fz 63 -148.2 fz 24 -92.64 fz 81 -66.171 fz 77 -169.4 fy 14 -111.16 fz 95 -79.406 fz 91 -169.4 fz 14 -129.58 fz 109 -92.640 fz 105 -169.4 fx 14 -148 fz 20 -105.87 fz 16 148 fx 20 105.87 fx 16 hatem h. al-taee al-khwarizmi engineering journal, vol. 4, no. 2, pp 46-58 (2008) 57 references [1] xie,m., and steven,g.p., " evolutionary structural optimization" university of sydney, australia. 1997. [2] haftka, r. t., "elements of structural optimization" 3th edition, kluwer academic publishers, netherlands, 1992. [3] marcelin,j.l., and trompette,p.h., "optimal shape design of thin ax symmetric shells" engineering optimization ,vol.13,p.p.109117,1988. [4] patnaik, s. n., and sankaran, g.v.," optimum design of stiffened cylindrical panels with constraint on the frequency in the response of initial stresses. int. j. for numerical methods in engineering. vol. 10, 1976. [5] ding,y., " shape optimization of structures" computer and structures, vol.24, no.6, p.p. 975-1006,1986. [6] lagaros,n.d., and papadrak,m., "optimum design of shell structures with stiffening beams" national technical university of athens.2004. [7] ostwald, m., "multi criteria optimization of sandwich cylindrical shells under combined loads with core of different mechanical properties", poznan university of technology, institute of applied mechanics, poland.1996. [8] chu, d. n., xie, y. m., hira, a., and steven, g.p., "evolutionary structural optimization for problems with stiffness constraints " finite element in analysis and design, no.21, p.p 239-251, 1996. [9] venkataraman, s., "modeling, analysis optimization of stiffened cylindrical plates for reusable launch vehicles structures" phd thesis, u.o.florida, 1999. [10] ding,y., "optimum design of sandwich constructions" the royal institute of technology, stockholm, sweden.1987. [11] dr. lyenger, n.r., "optimization in structural design" journal of engineering mechanics. vol.120, no.5,may.1999. [12] lagaros,n.d., and papadrak,m. "automatic structural optimization of stiffened shells" national technical university of athens. 2002. [13] ravi, s. bellur., "optimal design of stiffened plates" msc thesis. university of toronto.1999. [14] timoshenko, s.p., (1961), theory of elastic stability, mcgraw-hill, new york. hatem h. al-taee al-khwarizmi engineering journal, vol. 4, no. 2, pp 46-58 (2008) 58 انتصميم األمثم نتراكيب انصفائح انمقواة انمعرضت انى حمم ساكن عادل عباس انموسوي محمذ عهً صيهود. حاتم هادي انطائً د. د جامعت بابم/ كهيت انهنذست/ قسم انهنذست انميكانيكيت انخالصت يزطٛس ثسشعخ خالي اٌعمٛد اٌّبضيخ ِع اٌعذيذ ِٓ طشق االِثٍيخ اٌّخزٍفخ اٌزي يّىٓ اسزعّبٌٙب ٌٍذصٛي (اٌزصّيُ األِثً)أخز ِجبي االِثٍيخ اٌٙيىٍيخ اٌجضء األٚي يزضّٓ الزشاح رمٕيٗ عذديٗ اعزّذد طشيمٗ اٌعٕبصش اٌّذذدح وأسبط ٌٙب , يزضّٓ اٌجذث جضئيٓ. عٍٝ ٘يىً يزّيض ثٛصْ ألً ِٚمبِٚخ ِمجٌٛٗ طشيمٗ اٌعٕبصش اٌّذذدح ثبسزخذاَ عٕبصش راد خٛاص (صيبغخ)اٌزمٕيخ رضّٕذ ّٔزجخ . ٌزٛضيخ سٍٛن اٌصفبئخ اٌّمٛاح رذذ رأثيش ظشٚف األدّبي اٌسبوٕخ . أْ ٘زٖ إٌّبرج سٛف رزّيض ثزٌه ٚاْ وً ّٔٛرج يسزعًّ أٔٛاع ِخزٍفخ ِٓ اٌزمٛيبد. سثطذ ٌخٍك ّٔبرج ثغيٗ أيجبد اٌزصّيُ األِثً ٌٙب (isotropic) ِزجبٔسخ ٘زح اٌطشيمخ طجمذ في ٘زا اٌجذث ٌزطجيمٙب عٍٝ اٌصفبئخ (.meso)اٌجضء اٌثبٔي يزضّٓ رٛضيخ اٌزصّيُ االِثً ٌٍّٛديً اٌّمزشح ثبسزخذاَ رمٕيٗ االِثٍيخ اْ . ثذيث اْ اٌشىً اٌّزجمي يزجٗ ٔذٛ رشويت أفضً, اٌّمٛاح ٚرعزّذ ٘زٖ اٌطشيمخ عٍٝ فىشٖ ثسيطخ ٚ٘ي ثبألصاٌٗ اٌجطيئخ ٌٍّبدح اٌغيش اٌّؤثشح ِٓ اٌزشويت يّثً . اٌزّثيً اٌشيبضي ٌٙزٖ اٌطشيمٗ ربِخ في ٘زا اٌجذث ثبٌجشِجخ اٌىبٍِخ ٚاٌزعذيً اٌّطٍٛة ثذيث رىْٛ لبثٍٗ ٌٍزطجيك عٍٝ رشاويت أخشٜ ٚثششٚط جذيذح إِب ٘ذف رذميك االِثٍيخ فسيّثً ثٛصْ اٌزشويت ثيّٕب رزّثً اٌميٛد , ٚاسرفبعٙب ِزغيشاد اٌزصّيُ (honeycomb stiffeners)سّه اٌصفيذخ ٚسّه اٌزمٛيبد (.von misses)ثئجٙبد اٌفْٛ ِبيسض al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 4, no. 4, pp 37-44 (2008) effect of grain and calcinations kaolin additives on some mechanical and physical properties on low density polyethylene composites zanaib y. shnean department of chemical engineering/ university of technology (received 30 january 2008; accepted 10 september 2008) abstract in this work, a composite material was prepared from low-density polyethylene (ldpe) with different weight percent of grain and calcinations kaolin at temperature of (850 o c) using single screw extruder and a mixing machine operated at a temperature between (190-200 o c). some of mechanical and physical properties such as tensile strength, tensile strength at break, young modulus, and elongation at break, shore hardness and water absorption were determined at different weight fraction of filler (0, 2, 7, 10 and 15%). it was found that the addition of filler increases the modulus of elasticity, elongation at break, shore hardness and impact strength; on other hand, it decreases the tensile strength and tensile strength at a break. absorption test was carried out in water at different immersion times and different composite .the results of absorption show that it obeys fick’s law and after the addition of kaolin the amount of absorption decrease. calcinations kaolin filler produces better mechanical properties , than grain kaolin fillers. keywords: composite, low-density polyethylene, kaolin. 1. introduction: materials are classified as metals, alloys, ceramics, glasses, composites, polymers, and semiconductors (1). ceramics can be defined as inorganic crystalline materials, probably the most "natural "derived materials. they are strong, serve as good electrical and thermal insulators, often resistant to damage by high temperature and corrosive environments, but are mechanically brittle .advanced ceramics are used in substrates that house computer chips, sensors and actuators, capacitors, wireless communications, spark plugs, inductors, and electrical insulation (2,3) . its whiteness and plasticity make it extremely suitable for its extensive use as a filler, extender, ceramic raw material and pigment. the theoretical structural formula of kaolin is al2o3.2sio2.2h2o. it is highly refractory clay and has a melting point above 1800c used by itself. kaolin is white, soft, plastic clay mainly composed of fine-grained plate-like particles (4, 5) . composites are made from different types of materials. they provide unique combinations of mechanical and physical properties that cannot be found in any single material. it is light weight, strong, ductile, high temperature resistant materials as well as hard, yet shock-resistance, cutting tools (2, 5) . ldpe is defined by a density range of 0.9100.940 g/cm³. it is unreactive at room temperatures, except by strong oxidizing agents, and some solvent causes welling. it has more branching, so its intermolecular forces are weak, with lower tensile strength, and its higher resilience. also, since its molecules are less tightly packed and less crystalline because of the side branches, its density is lower (1, 2) . many workers investigated the physicomechanical properties of filled polyethylene with additives.vlasova (6) studied the influence of the degree of filling and the nature of the fillers on the zanaib y. shnean al-khwarizmi engineering journal, vol.4, no.4, pp 37-44 (2008) 38 properties of pe composites obtained by polymerizing ethylene on the surface of the filler particles. he found that the breaking stress and relative elongation at rupture with rise in the degree of filling diminish, while the elasticity modulus on stretching and the toughness of the polyethylene–kaolin composites rise. the scales of change in the properties of the composites with the degree of filling are determined by the nature of the filler. tanaka and et al. (7) studied the dielectric properties of ldpe filled with aluminum silicate clay fillers by thermally stimulated currents and time domain dielectric spectroscopy. they investigated the change of the charge storage behavior and related dielectric responses by analyzing the effect of the particle size of the fillers and that of surface modification of the fillers. dubois (8) studied the interfacial adhesion in polyethylene-kaolin composites using a stearic acid and maleic anhydride-grafted polyethylene as potential interfacial agents with the consideration of the efficiency of a minosilane-surface-treated kaolin. they found that the melt index of the enhanced interfacial filler-polymer has been decreased they also conclueled that comparing with other low molecular weight additives such as stearic acid and aminosilane, anhydride-grafted pe has very efficient in improvement the impact resistance of hdpe kaolin composites even at low contents. privalko and pedosenko (9) characterized the injection-molding and blow-molding grades of hdpe composites containing up to 30 vol.% of calcinated kaolin. polyethylene/kaolin composites by measurements of melting temperatures (tm), heats of fusion (hm) and roomtemperature densities. they showed that both tm and the degree of crystallinity of a polymer matrix proved essentially unchanged regardless of filler content and/or presence of a custom coupling agent. privalko et al. (10) studied the characterization of samples of the blow-moulding grade hdpe filled with kaolin by wide-angle xray scattering, micro hardness and stretching calorimetry techniques. they observed that crystallinity of the polymer matrix in the filled samples remains essentially the same as that in the neat polymer regardless of the filler content. khazraji (11) studied the mechanical ,thermal and electrical properties of epoxy resin reinforced with different clays and minerals namely bentonite,koalinite,zeolite,selenium oxide, barium titan ate and calcium carbonate. the modified epoxy resin was prepared using physical blends of this resin with 50% of additive materials, in a addition to using different percentage of iraqi zeolite (5, 15 and 25%) .it was found that the impact strength of the epoxy reinforced with 5% of iraqi zeolite was doubled the hardness of the sample reinforced with 5% of barium titanate was increased by 7% and the modulus of elasticity of the sample reinforced with 5% zeolite was increased by 156 % compared with the non treated sample. abed-alhakem (12) studied the effect of iraqi raw ceramic kaolin and boxide on epoxy resin, he showed that mechanical properties of composites filled with relatively small particles increased with increasing filler content, and decreasing filler size. al-neamee (13) investigated the mechanical and physical properties of pe reinforced with alumina. she found that mechanical properties increase with increase of wt% of alumina and the absorption water was decreased with the addition of filler. in the present work, a composite material was fabricated using ldpe with different weight fraction of kaolin by using single screw-extruder to obtain material with the desire mechanical and physical properties. 2. experimental: 2.1 materials: commercial ldpe was used in this work; it was supplied by international company for chemical and plastic industries. the melt flow index and the density of the material were 20gm/10min and 0.9235 g/cm 3 , respectively. grain kaolin has particle size of 42 μm and density 2.23 g/cm 3 and melting point 1755c.it is available in high purity and large quantity at low cost. its chemical composition is (al2o3=39.5%, sio2= 46.5%and h2o=14.0%). calcined kaolin has particle size of 39 μm and density 2.53 gm/cm 3 . it has good strength, stiffness, and available at low cost .its chemical composition is (sio2=59.19%, al2o3= 32.28%, fe2o3= 2.94%, tio2=1.43%, cao= 0.46%, l.o.i= 10.93% ). 2.2 method: in this work, mechanical mixing was used to prepare composite materials from ldpe / kaolin using extruder machine. ldpe and kaolin were mixed with various compositions of filler (0, 2, 7, 10 and 15%). this mixture was then fed into 25mm single screw extruder. this machine is supplied with electrical heater, the materials is zanaib y. shnean al-khwarizmi engineering journal, vol.4, no.4, pp 37-44 (2008) 39 melted by shearing it between the barrel and the smooth cylindrical part of the screw, finally the flat –end part of the screw act as a pump forcing the molten, composite materials out. the barrel temperature was monitored and controlled by thermostats. the die temperature was also controlled by a thermostat and was adjusted, together with barrel temperature to yield uniform output. the extrusion condition were listed in table (1). the extruder produced in the form of about 2 mm diameter monofilament was cooled in water. the monofilament produced by using a screw speed from (0-50) r.p.m. was uniform and opaque, which was cut in the form of granules of 3-4 mm length with the help of granules. the sheet was prepared by hot pressing the granules between hydraulic press at 190 o c for ldpe and ldpe/kaolin. a pressure of 10 mpa was applied for 5min to allow the composite to melt and spread out between plates. the pressure was removed and the mold sheet was quenched in water at room temperature. 2.3 test method: 2.3.1 tensile strength test: it can be defined as the maximum tensile sustained by the material being tested to its breaking point (2) . tensile strength = f/a …(1) where: f = force applied in n, a = cross section area mm 2 . the tensile strengths values were determined by using tensile test according to astm d638 (15) . tensile properties were obtained using zwick universal testing machine. the cross head speed was 10mm/min, and the standard literature for tensile test, dumbbell -shaped was the general purpose test piece for plastic materials according to astm (d638), so test specimens type 1434 with a thickness of 4mm used in this work. elongation was measure by using zwick machine. the measurement was carried out according to the test specification of astm (d638). elongation% was calculated using eq: elongation= 100   lengthgaugeoriginal lengthguageoriginallengthgaugefinal …(2) 2.3.2 shore hardness test: hardness is a measure of a material resistance to localized plastic deformation (1) . shore d hardness was used to determine the hardness of the polymer materials, maximum test load: 50 n at shore according to astm. 2.3.3 impact strength test: the degree of resistance of a polymeric material to impact loading is a piece of concern in some applications (2) . charpy test was used to determine the impact strength of the polymeric material, the samples of impact test were notched by (notch instrument) according to astm (d256-87) (13) . all the specimens of impact test of blend before and after reinforcement kaolin filler was standard i.e. of (10×4×55) mm. impact strength is calculated by using the eq: i.s=u/a (j/m 2 ) ….(3) where: i.s = impact strength (joule/ m 2 ) u = energy of fracture in (joule), a = cross section area in (m 2 ). 2.3.4 modulus of elasticity test: the modulus measures the resistance of a material to elastic deformation, for linear elastic materials the stress  is the related to the strain  by young's modulus.  (hooke's law).  =   …(4) three point system was used to determine, modulus of elasticity is calculated by using the following relation: e =       deflection mass       i gl 48 3 … (5) i = 12 3db …(6) where: i = engineering bending momentum, d = width of samples (mm) b = thickness of samples(mm) g = gravity(m/sec 2 ), l = sample length(mm) zanaib y. shnean al-khwarizmi engineering journal, vol.4, no.4, pp 37-44 (2008) 40       deflection mass : is the slope of linear part of mass deflection curve obtained (1,2) 2.3.5 absorption test: water absorption test was used to determine the coefficient of absorption by using electronweighing type satorius (germany). water tests were conduced in the temperature range (32 ±2) o c. in order to determine the water absorption(20) we use the following equation: (m2-m1)/m1 ×100= water absorption % …(7) where: m2-m1= m is the variation in weight gain with time m1: the original dried specimen weight and from a known area we can find the water absorption for area by using the following equation: m/a= (m2-m1)/a (g/cm 2 ) …(8) table 1 extrusion parameter. polymer température °c screw speed (rpm) zone1 zone2 zone3 zone4 ldpe 150 170 220 190 50 ldpe/kaolin 150 190 250 220 50 3. results and discussion figure (1) shows the variation of tensile strength of ldpe at different wt.% of grain and calcined kaolin. from this figures, it is clearly seen that the tensile strength decreases with increasing wt% of kaolin. growths of micro cracks, which produce sharp stress gradients, are influenced by the shape and orientation of reinforcement. therefore, the voids and cracks do not transfer stress, making the material more compliable and there by generated increasing void space, which was responsible for stress propagation and thus lowering the material tensile strength (17) . the results agree well with results obtained by abed-alhakem (11) . also, from this figure, it is found that the tensile strength of composite material made of (ldpe/calcined kaolin) is higher than that of composite material made of (ldpe/grain kaolin ) and this is attributed to high strength that ldpe/calcinations kaolin filler possesses. this may be due to the differences in behavior between grain and calcined kaolin that stem from their composition and structure.the polymer composites that contain the calcined kaolin having a high mullite content have improved mechanical properties compared to a similar polymer that does not contain (2,4) . fig.1. the relation between the tensile strength of ldpe sample with different percentage of grain and calcined kaolin filler. figure (2) shows the relation between the tensile strength at break of ldpe at different wt.% of grain and calcined. from this figure it is clearly seen that the tensile strength at break decrease with increasing wt% of kaolin filler. the failure may happen to the material because of the influence of the fracture stress, which leads to crack appearing. these micro cracks collectively join to attain a macro-size which, at critical stress levels, becomes unstable, and this lead obstacles the transition of the stress. from this figure, it is found that the tensile strength at break of composite material made of ldpe / calcined kaolin is higher than that of composite material made of ldpe / grain kaolin and being due to 0 2 4 6 8 10 12 14 0 5 10 15 20 weight fraction % te n s il e s tr e n g th calcined grain zanaib y. shnean al-khwarizmi engineering journal, vol.4, no.4, pp 37-44 (2008) 41 ldpe/calcinations kaolin is harder and more rigid than ldpe/grain kaolin filler and also ldpe/calcined kaolin share the external stress with matrix better than ldpe/grain kaolin. this may be attributed to that, the tensile strength at break, which is effectively independent of microstructure. fig.2. the relation between the tensile strength at break of ldpe with weight fraction of grain and calcined kaolin filler. figure (3) shows the relation between the elongation at break of ldpe at different wt.% of grain and calcined. fig.3. the relation between elongation at break of ldpe with weight fraction of grain and calcined kaolin filler. the elongation at break is observed to increase on addition of kaolin filler. experimental results are reported for the determination of the elongation of ldpe filled with and filler of various at different filler contents. from these figures it is the effect of on the weight fraction elongation at break of polymeric composite is clearly seen from the figure one can find that the elongation at break of composite material made of ldpe/calcined kaolin is higher than that of ldpe/grain kaolin. figure (4) show the relation between the shore hardness and the weight fraction before and after reinforcement with filler for grain and calcined kaolin filler at different weight fraction. fig.4. the relation between shore hardness of ldpe with weight fraction of both grain and calcined kaolin filler. the additions of kaolin filler increase the hardness of composite material due to increase in the resistance strength of polymer to plastic deformation. this behavior may be due to the hard and high resistance to hardness of grain and calcinations kaolin filler material. the latter has a good ability to absorb the load applied by matrix ldpe and increase the resistance of matrix composed of ldpe and that will increase the binder force between the molecules of matrix with particulate reinforcement filler. the results agree well with results obtained by khazraji (10) . figure (5) shows the effect of weight fractions of grain and calcined kaolin fillers on the tensile modulus. from this figure it is clearly seen that the modulus of elasticity increase with increasing weight fraction of kaolin filler. the particle filler agglomerates hence reduced the strain value restriction the mobility of matrix chains. the mobility of matrix chains and agglomeration of particle filler is clearly indicated by the increase in young’s modulus (18) .also, from this figure, it was found that the modulus of elasticity of composite material made of ldpe / calcined kaolin were higher than those of the composite material made of ldpe / grain kaolin. thus in the present study there was a good improvement of modulus of elasticity of through ldpe/kaolin the addition of particulate kaolin on modulus of elasticity.calcined kaolin having a high mullite 0 2 4 6 8 10 12 14 0 5 10 15 20 weight fraction % te n s il e s tr e n g th a t b re a k calcined grain 0 50 100 150 200 250 300 350 0 5 10 15 20 weight fraction % e lo n g a ti o n a t b re a k calcined grain 0 10 20 30 40 50 60 70 80 90 100 0 5 10 15 20 weight fraction % s h o re h a rd n e s s calcined grain zanaib y. shnean al-khwarizmi engineering journal, vol.4, no.4, pp 37-44 (2008) 42 content may be distributed uniformly or nonuniformly within the polymer matrix to yield desired product properties. grain kaolin exists naturally in the hydrous form. in the hydrous form, kaolinite minerals form crystal structures that are linked together by hydroxyl containing moieties. hydrous kaolin may be converted to calcined kaolin containing a major amount of mullite by thermal processes. such processes result in a dehydroxylation of the kaolin and an aggregation of the particles, and convert the crystal structure to an amorphous form (18) . the results agree well with results obtained by vlasova (6) and abed-alhakem (13) . 0 50 100 150 200 250 300 0 5 10 15 20 weight fraction % m o d u lu s o f e la s it y calcined grain fig.5. the relation between modulus of elasticity of ldpe with weight fraction of both grain and calcinations kaolin filler. figure (6) shows the variation of impact strength of ldpe at different wt. % of grain and calcined kaolin. from this figure, it is clearly seen that the impact strength increases with increasing weight fraction of kaolin. this may be due to a good adhesion between the matrix and filler. also, from this figure, it is found that the impact strength of composite material made of ldpe/ calcined kaolin is higher than that of composite material made of ldpe/ grain kaolin and this is attributed to high strength that ldpe/ calcined kaolin filler possesses. because the structure of kaolin is not symmetrical the crystal layers become highly polarized. the polarization of the layer crystals allows the kaolin to adsorb water molecules (which are also polar) between the layers. fig.6. the relation between impact strength of ldpe with weight fraction of both grain and calcined kaolin filler. diffusion is the process by which matter is transported from one part of the system to another as a result of random molecular motion. in general, diffusion behavior and transport in glassy polymers have been classified according to the relative rates of mobility of the penetrate and of the polymer segments. figures (7and 8) show that adsorption water is reduced with increase in weight fraction of filler, because has a high ability to bear water compared with polymeric material. the absorption percent was reduced with increase in the weight fraction of filler. the amount of water absorbed will depend primarily upon the chemical nature of the polymer matrix and the environment to which it exposed. the results agree well with results obtained by al-neamee (14) . 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0 5 10 15 20 t -1/2 w t % w t= 0 % w t = 2 % w t= 7 % w t = 10 % w t =15 % fig.7. shows the relation between the weight gains %of ldpe/ grain kaolin with the square root of time. 0 0.1 0.2 0.3 0.4 0.5 0.6 0 5 10 15 20 weight fraction % im p a c t s tr e n g th calcined grain zanaib y. shnean al-khwarizmi engineering journal, vol.4, no.4, pp 37-44 (2008) 43 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 0 5 10 15 20 t -1/2 w e ig h t g a in % w t= 0 % w t = 2 % w t = 7 % w t = 10 % w t =15 % fig.8. shows the relation between the weight gains % of ldpe/calcined kaolin with the square root of time. 4. conclusion: the addition of kaolin was found to improve the modulus of elasticity, shore hardness, impact strength and elongation at break. on other hand, pure ldpe has a higher value of tensile strength. water absorption values were observed to be the highest in pure ldpe, and these values decreases with increasing different percentage of kaolin. kaolin calcinations filler produces better mechanical, and physical than grain kaolin fillers. 5. references: [1] donald, r., askelane, w., and phule, p.p., "the science engineering of materials", 4th edition, john wiley, new york, (2003). [2] callister w.d.jr“ materials science and engineering”: an introduction , 5th edition, wiley, (2000). [3] theng,b.k.g."formation and properties of clay-polymer complexes", elsevier scientific publishing company, new york, p 353, (1979). [4] alexander. and dubois," polymer-layered silicate nan composites”: preparation, properties and uses of a new class of materials,mater. sci. eng., 28, p ( 1-63), (2000). [5] worral, w.e. “clay and ceramic raw materials” applied science publishers, ltd.london, (1975). [6] vlasova ,“influence of the degree of filling and the properties of the fillers on the strainstrength properties of synthetic pe composites “, polymer science ussr vol.30,no.7,pp.(1487-14941),(1988). [7] tanaka j.,yin w.and d. damon; “journal. of applied polymer science" issue 4-7, october , p (697 – 701), (1993). [8] dubois ph, “journal. of applied polymer science”, vol.56,issue9, p1093, (1995). [9] privalko e.g.and pedosenko.v. ,“ journal of applied polymer science”,vol.73 , p (12671271), (1999) . [10] privalko.,v. p. "journal of materials science", october,vol.34, no.3, (2004). [11] al-ghazraji h.g.,m.sc thesis, university of baghdad,(2002). [12] abdl-hakem, r.h m.sc.thesis u.o.t.,“the effect of iraqi raw ceramic (kaolin and boxide) on the epoxy resin”, (2003). [13] shatha sadik hassan al-neamee, r.h m.sc. thesis u.o.t., “a study on pe. kaolin powder particulate composites”, (2002). [14] annual book of astm, section8, vol.08.01 plastic, ”am. soc. test mat.”, philadelphia,(1989). [15] astm, d 790 m,p.(290-297), (1986). [16] nielsen l. e. and landel, r. f., "mechanical properties of polymers and composites", 2nd edition, marcel decker, inc., 545 pp, (1994). (internet) [17] apicella a.," water sorption and mechanical properties of a glass reinforced polyester resin", journal of composite, vol.13, no.4, p(406-408), (1982). http://www3.interscience.wiley.com/journal/104034415/issue (2008 )44-37، صفحة 4، العذد 4زينب يىسف شنين مجلة الخىارزمي الهنذسية المجلذ 44 على بعض الخصائص الكاؤولين (الحبيبات والكلسنة)ثير اضافات تأ الميكانيكية والفيسياوية على متراكبات البىلي اثلين الىاطئ الكثاف زينب يىسف شنين اندايعت انخكُٕنٕخيت / لسى انُٓذست انكيًيأيت الخالصة ٔانخي ْي عبارة عٍ يخهٕط بٕنيًري ، يخكٌٕ يٍ يسج بٕني اثهيٍ انٕاطئ انكثافت يع انكاؤٔنيٍ ححضير يٕاد يركبت في انبحث انحاني حى حخرأذ بيٍ درخاث حرارةٔرنك باسخخذاو خٓاز انباثمت األحاديت حيث حى حشغيهٓا عُذ . ٔانغير يحرٔق (و °850)انًحرٔق بذرخّ حراريت يثم ٔبعذ رنك خرث دراست بعض انخصائص انًيكاَيكيت.حى اسخخذاو ياكُت انبثك أحاديت انهٕنب في ححضير انًٕاد انًخراكبت. (و 150-200°) ٔندًيع انًخراكباث انًحضرة ٔلٕرَج انُخائح انًسخحصهت يع حهك انخي لٕة انصذيت ٔصالدة شٕر،،انشذ ٔإخٓاد انشذ عُذ انكسر ٔاالسخطانت يعايم : يٍ انُخائح انخي حى انحصٕل عهيٓا نٕحع ازدياد كم يٍ. ٔخرث انفحٕصاث بكسٕر ٔزَيّ يخخهفتحعٕد نًادة األساش بًفردِ حى إخراء فحص االيذصاصيت نكم . بسيادة َسبت انخهظ أنٕزَيصالدة شٕر ٔلٕة انصذيت َٔمصاٌ يمأيت انشذ،االسخطانت عُذ انكسر ،انًرَٔت أٌ يٍ انُخائح انخي حى انحصٕل عهيٓا حبيٍ .ًَٕرج لبم ٔبعذ انخذعيى بًسحٕق انكاؤؤنيٍ ٔأظٓرث انُخائح َمصاٌ في االيذصاصيت بعذ انخذعيى . َخائح أفضم يٍ انكاؤٔنيٍ انغير يحرٔقٖانكاؤٔنيٍ انًحرٔق أعظ 9099 al-khwarizmi engineering journal,vol. 12, no. 1, p.p. cultivation of microalgae for biomass production department of chemical engineering (received abstract air lift reactors are widely used in the chemical and biochemical heat transfer. the main advantages of airlift low shear rate, high capacity, good mixing in this work, growth characteristics photobioreactor for biomass production commercially available 20:20:20+te npk growth rate and biomass productivity of concentration (20-80 mg/l), inlet air flow rate biomass productivity of chlorella vulgaris the results of batch operation showed increasing of npk nutrient concentration used but the access to the stationary phase of growth growth was also increase with the increase in air flowrate to a limit then decrease photobioreactor can be operated in semi batch step which was 40 mg/l npk nutrients concentration content were harvested and the maximum biomass productivity days. keywords: airlift photobioreactor, chlorella vulgaris, 1. introduction the production of biodiesel biomass as a renewable source interest in recent years. algae produce oil more than the rest of biodiesel feedstocks such as soybean, corn, rapeseed, palm, and yellow grease per unit of growing area as well as algae can provide different types of renewable biomass such as proteins and lipids [1]. microalgae are microorganisms via photosynthesis process. it convert and carbon dioxide into biomass typically found in freshwater and marine systems. microalgae reproduction occurs primarily by vegetative asexual cell division [2]. khwarizmi engineering journal,vol. 12, no. 1, p.p. 9099 (2016) al-khwarizmi engineering microalgae chlorella vulgaris in airlift photobioreactor biomass production using commercial npk nutrien saad hanash ammar chemical engineering / college of engineering/ al-nahrain university email: saad_cheminet@yahoo.com (received 5 may 2015; accepted 7 july 2015) lift reactors are widely used in the chemical and biochemical applications as effective of airlift contactor compared with simple bubble column rate, high capacity, good mixing and liquid circulation without mechanical agitators this work, growth characteristics of chlorella vulgaris microalgae were studied in an internal loop production. the bioreactor operated under batch and semi-continuous culture mode npk fertilizer as nutrients. the experiments were conducted to evaluate the of chlorella vulgaris microalgae as affected by several factors such as nutrients flow rate (2-8 lpm), and harvesting ratio (10-30 vol. chlorella vulgaris was determined as changes in optical density using ed that the growth rate of chlorella vulgaris microalgae increasing of npk nutrient concentration used but the access to the stationary phase of growth growth was also increase with the increase in air flowrate to a limit then decrease. on the other photobioreactor can be operated in semicontinuous mode successfully by choosing the optimum conditions npk nutrients concentration and 6 lpm and air flowrate and the maximum biomass productivity was 0.142 g/l.day when harvested irlift photobioreactor, chlorella vulgaris, microalgae, biomass, npk nutrients. biodiesel from algae took a great algae biomass can produce oil more than the rest of biodiesel , rapeseed, oil per unit of growing area as well as algae can provide different types of carbohydrates, that can grow t converts light, water typically found . microalgae rimarily by vegetative in addition to the oil production, wh used as biodiesel, there is a wide range of applications for microalgae products, from foods to wastewater treatment, aquiculture, and hydrogen production [3]. the most productive microalgae studied researchers for biomass production are cyanophyceae (blue green al (green algae), bacillariophyceae chrysophyceae (golden-brown algae). chlorella vulgaris is one of the few microalgae can accumulate high content of lipids or carbohydrates under selected conditions chlorella vulgaris is a spherical single green microalgae containing chlorophyll b which it uses for photosynthesis. vulgaris has potential in al-khwarizmi engineering journal (2016) t photobioreactor nutrients nahrain university effective contactors for mass and compared with simple bubble column are ease of construction, agitators and circulating pumps. in an internal loop airlift continuous culture mode using the experiments were conducted to evaluate the microalgae as affected by several factors such as nutrients vol.%). the growth rate and using uv-spectrophotometer. microalgae was increase with increasing of npk nutrient concentration used but the access to the stationary phase of growth was delayed. the rate of . on the other hand the airlift choosing the optimum conditions from the and air flowrate. several ratios of reactor harvested 10 vol.% every two oil production, which can be , there is a wide range of applications for microalgae products, from foods to wastewater treatment, aquiculture, and even the most productive microalgae studied by for biomass production are (blue green algae), chlorophyceae (green algae), bacillariophyceae (diatoms) and brown algae). [1,3] is one of the few microalgae can accumulate high content of lipids or carbohydrates under selected conditions. is a spherical single-celled green microalgae containing chlorophyll-a and b which it uses for photosynthesis. chlorella has potential in both foods other saad hanash ammar al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 9099(2016) 91 industries such as pharmaceutical, cosmetics, and biofuel industries. chlorella vulgaris is known as one of the fastest growing green microalgae. the optimum conditions for cultivation of chlorella vulgaris are temperature of 20 25 oc and ph of 4 – 7 [3, 4]. chlorella vulgaris biomass when dried consists of, approximately, 40% protein, 25% oil, 20% carbohydrate, 5% fiber, and 10% minerals and vitamins. despite its highly efficient photosynthesis which allows it to produce more oil and protein than most other plants. the lipid content in chlorella vulgaris could be increased significantly between 50% and 70% [5]. airlift reactors are contacting devices with two interconnecting and distinct zones only one of which is usually sparged by gas called riser whereas the other region is called downcomer which does not receive the gas. the different gas holdup in the gassed and ungassed zones results in different bulk densities of the fluid in these regions which causes circulation of the fluid in the reactor by a gas-lift action. generally airlift contactors exist in two forms internal loop and external loop. in internal loop reactor, regions are separated either by a draft tube or a split cylinder while in external loop, riser and downcomer is separated physically by two different tubes. mixing is done by bubbling the gas through sparger in the riser tube without any physical agitation. riser is similar to bubble column where sparged gas moves upward randomly and haphazardly [6]. because the simplicity in design and construction, clear flow patterns, good mixing, low required mechanical power, less shear for a given quality of mixing, and many other advantages airlift reactors may be used for several industrial applications whether for two or three phase systems including aerobic fermentation (such as citric acid, biomass from bacteria and vinegar), microorganism cultivation, and metal bearing wastewater treatment [7]. as a comparison between the four main types of photobioreactors used for microalgae production, table (1) show the typical advantages and disadvantages of these closed systems [8]. table 1, typical advantages and disadvantages of the four main types of closed bioreactors for microalgae cultivation. reactor type typical advantages typical disadvantages fat plate reactor • shortest oxygen path • low power consumption • low photosynthetic efficiency • shear damage from aeration tubular/ horizontal reactor • high volumetric biomass density • oxygen accumulation photoinhibition • most land use airlift/vertical reactor • best exposure to light/dark cycles • greatest gas exchange • least land use • high photosynthetic efficiency • high liquid circulation • support costs • scalability bubble column/vertical reactor • best exposure to light/dark cycles • greatest gas exchange • low photosynthetic efficiency cstr • good mixing • easy to scalable • high power consumption 2. the objective the objective of the present work is to cultivate the chlorella vulgaris microalgae in internal loop draught tube airlift photobioreactor for biomass production using commercial 20:20:20+te npk fertilizer as low cost nutrients under different experimental conditions. the experimental conditions studied in this work include nutrients concentration (20, 40, 60, and 80 mg/l), inlet air flowrate (2, 4, 6, and 8 lpm), harvesting ratio (10, 20, and 30 vol.%) and operation mode (batch and semi-continuous mode). saad hanash ammar al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 9099(2016) 92 3. experimental 3.1. sample of microalgae strain collection and purification of chlorella vulgaris strain was done at the market research and consumer protection center, university of baghdad using serial dilution culture method. after receiving the isolated chlorella vulgaris strain the sample was immediately incubated in the algal-culture room under controlled conditions of temperature (20-27°c), photoperiod (18 hr light/4 hr dark) and light (1 k lux by two florescent tubes each 13 watt). these cultures were maintained in five 0.5 l flasks (300 ml working volume), with aeration with filtered air and using 20:20:20+te npk fertilizer with concentration of 30 mg/l as nutrients (composition, preparation and sterilization of culturing medium are showed in the later sections). the cultures were subcultured every 8 days by transferring cells to a fresh medium (10 ml culture was added to each flask and then completed to 300 ml working volume of fresh media solution). figure (1) shows the starter culture of chlorella vulgaris microalgae (in flasks) while figure (2) shows the photographic view of the batch cultivation using n:p:k+te fertilizer media with time in day. fig.1. experimental setup of chlorella vulgaris strain incubate fig. 2. photographic view of the chlorella vulgaris microalgae cultures with time. 3.2. preparation of culturing medium commercial available n:p:k 20:20:20+te fertilizer (provided from kule® inc.) was used as high water soluble and low cost nutrients for biomass culture with combination of 20:20:20+te. table (2) shows the composition of each element in this commercial npk fertilizer. four concentration of npk fertilizer 20, 40, 60, and 80 mg/l were used in this work by dissolving the appropriate amount of the npk fertilizer in ro water. table 2, composition of commercial n:p:k+te fertilizer. constituents concentration % n:p:k (nitrogen:phosphorus:potassium) 20:20:20 n as urea 2.1% total n = 20% n as ammonia 17.9% p as phosphorus oxide 20% k as potassium oxide 20% mg 0.1 % zn 0.05 % mn 0.05 % fe 0.1 % cu 0.05 % b 0.02 % vitamin b 0.0005 % saad hanash ammar 3.3. equipment and procedure before conducting cultivation experiments the bioreactor and to minimize the risk of contamination or infection by potential pathogens and other microorganism, species in the flask medium the nutrient media, glasses equipment must to be sterilized. the alternative method used for sterilization of nutrients solution was by using a gas stove as arrangement shown in figure (3) where a flask with nutrient medium solutions are water at a temperature of (70-80°c) for about 30 minutes. the nutrient medium in the flask should not be allowed to boil as this will nutritional value of the medium. fig. 3. a way of sterilization of flasks and medium. to avoid contamination by condensation air tube airlines, the air should be filtration through an in-line filter before entering the riser section of the airlift photobioreactor; therefore aeration filter unit contain cotton and activated charcoal must be used figure (4). fig. 4. aeration filter used in avoid contamination in the air lines. also the airlift photobioreactor was st by fuelled with a solution of about 2 al-khwarizmi engineering journal, vol. 12, no. 93 experiments in o minimize the risk of contamination or infection by potential pathogens in the flasks and , glasses and . the simple and sterilization of a gas stove as the ) where a flask are kept in the hot 80°c) for about 2030 minutes. the nutrient medium in the flask as this will vary the a way of sterilization of flasks and nutrients to avoid contamination by condensation in the the air should be dried by line filter before entering photobioreactor; contain cotton and as shown in used in avoid contamination photobioreactor was sterilised about 200 ppm sodium metabisulfide decontamination agent bioreactor for about 20 minute. the airlift photobioreactor shown schematically in figure ( two concentric columns made from perspex material. the internal tube ( riser) is 8 cm diameter and outer tube is 80 cm height and 12 cm diameter. the air is passed through the internal column to become the riser this was done by 25w pressure air compressor. the air distribution was done by small air porous stone. four tubes (13 watt each) were used to provide the light to the bioreactor. the height of internal tube (riser) from the bottom is 5 cm that give a free area about 251 cm2. the photobiore so that no air enters from the outside to the inside this was done by using one show a photographic view of the experimental airlift photobioreactor in use fig. 5. laboratory schematic. , no. 1, p.p. 9099(2016) (na2s2o5) as a hold in the airlift 0 minute. the airlift photobioreactor used in this work, shown schematically in figure (5), consisted of columns made from transparent . the internal tube (which is the 8 cm diameter and 60 cm height while the is 80 cm height and 12 cm diameter. air is passed through the internal column to become the riser this was done by 25w, 2 bar the air distribution was done by small air porous stone. four fluorescent tubes (13 watt each) were used to provide the light the height of internal tube (riser) from the bottom is 5 cm that give a free the photobioreactor is sealed so that no air enters from the outside to the inside using one-way valve. figure (6) show a photographic view of the experimental in use. airlift photobioreactor saad hanash ammar al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 9099(2016) 94 fig. 6. photographic view of the laboratory airlift photobioreactor in use. the experimental procedure was departed in two stages batch and semi-continuous mode. in all experiments the culture conditions of cultivation temperature, light and dark photoperiod cycle and ph were kept constant at 20-25 oc, 20:4 hr, and 4 – 7 respectively. • batch operation stage the purpose of this stage is to access to the highest level of growth rate of microalgae chlorella vulgaris and the best conditions of npk nutrients concentration and air flowrate were recorded to be used in the next stage (semicontinuous operation). therefore two sets of experiments were performed. in the first set four levels of npk nutrients concentration were used (20, 40, 60, and 80 mg/l) and fixing air flowrate on 2 lpm while in the second set the air flowrate were varied into four values (2, 4, 6, and 8 lpm) and the npk nutrients concentration was fixed on the value which gives a higher growth rate and shortest generation time from the first set. in all experiments 250 ml of stock culture was used then complete the reactor to its working capacity (6.6 liter) with ro water containing prespecified npk nutrients concentration. for counting about 1 ml sample was removed every day from the bioreactor and kept in a stoppered tube with 1 drop of iodine, which killed the cells. microalgae concentration was determined indirectly by optical density than by direct counting of cells or by cell dry weight. the optical density (cell absorption) was measured using uvvisible spectrophotometer by measuring absorbance at a wave length of 540 nm [9]. calibration curve for relationship between optical density and cell dry weight was formed by the following procedure [10]: the sample of microalgae was firstly centrifuged at 3000 r/min for 20 min to settling it into the bottom then it was dried by exposure to atmosphere for 24 hr and then dried at 105°c overnight. after drying, the algae were powdered. five culture samples were tested and the equation which is relating the biomass concentration in g/l with the optical density (cell absorption) in nm was determined. the equation is given in results and discussion section. the growth rate (k) and generation time (g) were also can be calculated by the following equations as given by [12]: � = ������� �� …(1) � = �� � � …(2) where xt and xo= final and initial populations at time t2 and time t1, respectively. because the culture was monitored every day therefore t2-t1=1. • semi-continuous operation stage this stage started after selecting reactor conditions air flowrate and npk nutrients medium concentration which give a best growth rate curve and after reaching the stationary phase of microalgae growth rate, a part of bioreactor content were removed by a ratio of 10, 20 , and 30 % as a harvesting ratio. then the bioreactor content compensated with a fresh medium all at once at the same time (i.e. fresh medium with prespecified concentration flows into the bioreactor, and the spent culture with prespecified harvesting ratio flows out) then the culture is allowed to grow for a given period and then the procedure is repeated for another harvesting ratio. in general table (3) shows the experimental setup and conditions for cultivation of chlorella vulgaris microalgae in airlift photobioreactor. table 3, experimental conditions for biomass culture of microalgae in airlift photobioreactor. parameter value cultivation temperature 20-25 oc ph 4-7 alternate light and dark photoperiod cycle 20:4 hr air flowrate (lpm) 2, 4, 6, and 8 npk nutrients concentration (mg/l) 20, 40, 60, and 80 liquid work volume in the bioreactor 6.6 liter harvesting ratio 10, 20, and 30 % saad hanash ammar al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 9099(2016) 95 4. results and discussion 4.1. batch mode runs the initial period of the airlift bioreactor operation was in a batch mode using different concentration of npk nutrients and air flowrate as described in experimental section. the growth curves of chlorella vulgaris microalgae in term of cell absorbance (nm) at different npk nutrients concentration and at air flowrate of 2 lpm were illustrated in figure (7). fig. 7. growth curves of chlorella vulgaris microalgae at different nutrients concentration and at air flowrate 2 lpm. all the growth curves showed about four growth phases of microalgae cultures. the first phase is induction or lag phase which little increase in growth rate as cell absorption (nm) occurs. in the second phase the growth rate increases exponentially this is depends on many factors such as algal species or type, light intensity and medium temperature. the third phase is the constant phase in which the cell density become relatively constant. finally declining growth rate when the cell divisions decreases because some factors become influential to growth rate such factors as npk nutrients concentration, ph, dissolved co2, light and contamination risk. since chlorella vulgaris is a heterotrophic and autotrophic, it can be easily cultivated in various synthetic media and even in sewage [11]. so the 20:20:20+te npk nutrients often succeed in culturing chlorella vulgaris microalgae and at a reasonable rate. at levels of 20 and 40 mg/l npk nutrients concentration the growth of chlorella vulgaris entered the stability phase in 5 days while at 60 and 80 mg/l npk nutrients concentration entered the stability phase in day 6 and 7 respectively. since nitrogen is the main limiting nutrient to microalgae growth [12], very high concentration in the media of microalgae growth may cause deactivation in the production of pigments necessary for photosynthesis [13]. therefore the high levels of npk nutrients concentration (60 and 80 mg/l) needs longer time to reach to the stability phase of growth. the calibrated data between the optical density and cell dry weight is shown in figure (8). fig. 8. calibration curve for relationship between optical density and cell dry weight. the five tested culture samples which are used to create the equation relating the biomass concentration in g/l with optical density (cell absorption) in nm by plotting these data and the equation is: y=0.211 x …(3) where the value y is the biomass concentration (g/l) and the value x is the optical density (cell absorption, nm). the chlorella vulgaris microalgae cultivation in the batch mode showed similarities in growth 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0 1 2 3 4 5 6 7 8 9 10 11 c el l a bs or pt io n (n m ) days 20 mg/l npk nutrients 40 mg/l npk nutrients 60 mg/l npk nutrients 80 mg/l npk nutrients saad hanash ammar al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 9099(2016) 96 behavior in all four levels of the npk nutrients concentration used. the final biomass dry weights were 0.317 g/l in 80 mg/l nutrients concentration medium, 0.298 g/l in the in 60 mg/l nutrients concentration, 0.225 g/l in 40 mg/l nutrients concentration and 0.2 g/l in 20 mg/l nutrients concentration. the maximum growth rate (k) and generation time (g) at each level of nutrient concentration can be calculated and shown in figures (9) and (10) respectively. it is clear that the maximum value of growth rate (1.30834 g/l.day) and shortest generation time (0.5298 day) where reported for 40 mg/l nutrient concentration. fig. 9. growth rate of chlorella vulgaris microalgae at different nutrients concentration. fig. 10. generation time of chlorella vulgaris microalgae at different nutrients concentration. therefore the nutrient concentration of 40 mg/l was selected to examine the effect of air flowrate in airlift photobioreactor. figure (11) shows the effect of air flowrate on growth of chlorella vulgaris at 40 mg/l npk nutrient concentration. fig. 11. growth curves of chlorella vulgaris microalgae at different air flowrate and at 40 mg/l npk nutrient concentration. as shown in the figure (11) the cell absorption increase with increasing air flowrate up to 6 lpm then decrease at 8 lpm. maximum growth rate and shortest generation time were achieved at about 6 lpm as shown in figure (12). this result can be explained when increasing air flowrate the holdup in the reactor increase and the mass transfer rate increase therefore the rate of growth of microalgae enhanced. but when further increasing in air flowrate above 6 lpm this increased gas holdup and bubble size decrease, the column becomes hazy leads to do not penetrate the light into the depth of the column and therefore decreases the growth rate. this is also explained by [14, 15]. 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0 1 2 3 4 5 6 7 8 9 10 11 c el l a bs or pt io n (n m ) day 2 lpm air flowrate 4 lpm air flowrate 6 lpm air flowrate 8 lpm air flowrate saad hanash ammar al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 9099(2016) 97 the best conditions in batch runs were reported as 6 lpm air flowrate and 40 mg/l npk nutrient concentration. these conditions were used in the experiments of semi-continuous mode runs. fig. 12. growth rate and generation time at different air flowrate 4.2. semi-continuous mode runs three different harvesting ratios (sometimes referred to as the dilution rate) were examined 10, 20, and 30 vol.%. the air flowrate and npk nutrient concentration were kept constant at 6 lpm and 40 mg/l respectively. the culture was continued for 28 day and the results are shown in figure (13). fig. 13. grown behavior of chlorella vulgaris microalgae under semi-continuous mode conditions. it can be seen from figure (13) when 10 % vol. was harvested from the bioreactor, the system takes two days (t1) to return to the stationary phase, three days (t2) for 20 % vol. harvesting and five days (t3) for 30 % vol. harvesting. steady-state conditions were achieved when a constant up-and-down pattern in the cell absorption was observed for each harvesting ratio. at the highest harvesting ratio (30 %vol.), when the cell absorption stabilized (steady-state condition), the up-and-down cell absorption ranged from 1.34 nm to 1.01 nm. at the middle harvesting ratio (20 %vol.), the cell absorption ranged from 1.33 nm to 0.69 nm. at the lowest harvesting ratio (10 %vol.), the cell absorption ranged from 1.32 nm to 0.59 nm. figure (14) shows the effect of harvesting ratio on the biomass productivity in g/l.day. it is clear that the maximum biomass productivity was 0.142 g/l.day every 2 days. fig. 14. biomass productivity (growth rate) at different harvesting ratio. 5. conclusions biomass production can be successfully accomplished by chlorella vulgaris microalgae cultivation in an experimental concentric-draught tube airlift photobioreactor designed and constructed in the laboratories of chemical engineering department, al-nahrain university. the photobioreactor operated under two modes batch and semi-continuous mode and using very low cost and available commercial 20:20:20+te npk nutrients. any required biomass productivity of chlorella vulgaris microalgae can be obtained and ranged from 0.0565 g/l.day at 30 vol.% dilution ratio to 0.142 g/l.day at 10 vol.% dilution ratio. 6. references [1] anders s. carlsson. jan b van beilen. ralf möler and david clayton. (2007). micro and macro algae, utility for industrial application. epobio project. university of new york. saad hanash ammar al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 9099(2016) 98 [2] khan, s. a., & rashmi, m. z. (2009). prospects of biodiesel production from microalgae in india. new delhi. india. renewable and sustainable energy reviews. [3] campbell, m. n. (2008). biodiesel: algae as a renewable source for liquid fuel, guelph engineering journal, (1), 2 7. [4] scragg, a.h., illman, a.m., carden, a., & shales, s.w. (2002). growth of microalgae with increased calorific values in a tubular bioreactor. biomass bioenergy, 23, 67–73. [5] sankar, m. & ramasubramanian, v. (2012). biomass production of commercial algae chlorella vulgaris on different culture media”, e-journal of life science issn 2250 – 1800, vol.1 (1) 56-60 [6] chisti m. y., (1981). airlift bioreactors, 1st edition, elisever applied science ltd., new york. [7] moresi, m., (1981). optimal design of airlift fermenters, biotechnol. bioeng. 23, 25372560, 1. [8] kunjapur, a. m. & eldridge, r. b. (2010). photobioreactor design for commercial biofuel production from microalgae, ind. eng. chem. res., 49, 3516–3526 [9] sigita, v., giulia, p., jolanta, k. and pietro, c. (2014). batch growth of chlorella vulgaris ccala 896 versus semicontinuous regimen for enhancing oil-rich biomass productivity, energies 2014, 7, 3840-3857. [10] chiu s. y., c. y. kao, c. h. chen, t. c. kuan, s. c. & ong, c. s. (2008). reduction of co2 by a high-density culture of chlorella sp. in a semi continuous photobioreactor, bioresour. technol, 99(9), 3389–3396. [11] richmond, a., (2004). handbook of microalgal mass culture, biotechnology and applied phycology”, blackwell, oxford. [12] mortin, f. p. and jens, b. (1996). nutrient control of alga growth in estuarine water, mar. ecol. prog. ser. 142, 261-272. [13] gopinathan c. p. (2013). differential growth rates of microalgae in various culture media, central marine fisheries research institute, research centre, tuticorin. [14] fogg, g.e. & thake, b., (1987). algal cultures and phytoplankton ecology. university of wisconsin press, madison, wisconsin. [15] gris, l. r. s., paim, a. c., farenzena, m. & trierweiler, j. o. (2013). laboratory apparatus to evaluate microalgae production, vol. 30, no. 03, pp. 487 497, july september, 2013. ���� 1، ا� د12 � � ا���ارزم� ا��� ��� ا��� م � ��� ���ر ،2016( 9099( 99 ����)� م���* ا�()' ا���ا$� ا����ي ا�%�$� chlorella vulgarisا�#�"�ت ا� ���� ا� ا�#��ري npk�#� ام ���د ب0 /.#�ج ا�,# � ا����+� ��� ���ر � ��� ا����� ا������و� / ا�������� ا��� �� / !"�# saad_cheminet@yahoo.com: �) و'&�% �� ا$ا� �� ا��3 6 � ��5ا� 12�34 درا� ت� ا�!�-، ھ*ا (&���7��89 ا��chlorella vulgaris &) -:�;" ا�)�و� يذ ا�<25& ا� (= ا��5ا2& ا�5�8ي&� a')�ج ا��ا4 � و"j*��ت �c(��hامو ا���)� f%gا���eم و ا���eم ا��(!&'�e"�� ھ�� تd8 �!�-ا���)�cم 5�8يا� �;�:-ا�. ا��5�8 ا��);� ا��kواط وھ& ت�nر�� ")�ح إ')�#� و ا���5 "!�ل ���)56 ا�)�nرب أ# �te .d+٢٠:٢٠:٢٠ npk ـا� ���د� ٨٠٢٠( ا��j*��ت ت ��] "z:5ا"h!�ة وتwx ھ�� ��7��89 ا��5�8 ا��) ]�6 / �) ٨-)٢ 4-ا�ا� ا��5اء ت�)^ و"!�ل ،(�( / "�� .)ح��n ٪ ٣٠ ١٠( ا��38د و'�% ،)د ا��)�d2 وأظ� ت��6 '�5 "!�ل أن ����eم ا��(!& ا�!��� ا��j*��ت ت ��] ز��دة �]داد "= chlorella vulgarisا�7��89 ا��"�c(ا��� �5ل و��g5ا� hإ� � " ح(h�w �" 4x)� 5ا��� i;c�� ھ��!h ��!" ح� hدة "!�ل # ��ن ا��5اء (& ا��;�:ا�5�8ي ا���[h 5داد "!�ل ا���[� j�*� .�" ���� أ4 ى '�ح� -�jlا�<25& ا� (= ا��5ا2& ا�5�8ي ";�:ت &) =mو f%g ح ��)� ا��n�h jوذ��" � ا���eم ا��" &!)� ��(4�hر وت9%�^ ا)<ا�< وف ا���38(���: d'���h ا�)5ا�& ت� / �) �٦) و / "��j ٤٠ت ��] ا��j*��ت و "!�ل # ��ن ا��5اء وا�)& : 6����ر وان أ�h3 ا��;�:"� "8)5ى '�7 :�ة ح�3دد �" ا')�#�� ا��5�8 ا��)��-٪ ١٠ د�ح3'�% :�� )�5م.�) / s ام( ٠.١٤٢ ��'dا���)38 ��nح �5"��. _1-12_ karima e. amori 1 al-khwarizmi engineering journal al-khwarizmi engineering journal, vol.3, no3,pp 1-12, (2007) parametric study of thermal behavior of thrust chamber cooling channels dr. karima e. amori mech. eng. dep., university of baghdad, iraq (received 6 march 2007 ; accepted 10 june 2007) abstract a numerical investigation is adopted for two dimensional thermal analysis of rocket thrust chamber wall (rl10), employing finite difference model with iterative scheme (implemented under relaxation factor of 0.9 for convergence) to compute temperature distribution within thrust chamber wall (which is composed of nickel and copper layers). the analysis is conducted for different boundary conditions: only convection boundary conditions then combined radiation, convection boundary conditions also for different aspect ratio (ar) of cooling channel. the results show that utilizing cooling channels of high aspect ratio leads to decrease in temperature variation across thrust chamber wall, while no effects on heat transferred to the coolant is indicated. the radiation has a considerable effect on the computed wall temperature values. ٌِkeywords: thrust chamber, multi layer wall, cooling duct, cfd. introduction the evaluating of convective heat transfer rates from high temperature combustion gases to the converging diverging nozzle of liquid fueled rocket engine is crucial for optimizing the design of thermal control systems and evaluation of thermomechanical behavior and fatigue of chamber liner to insure adequate long life operation. the liner of most current thrust chamber is fabricated from a high conductivity material, such as copper or copper based alloy, and closed out with nickel, incorporating cooling channels with liquid hydrogen as the coolant fluid as shown in fig. (1). armstrong and brogren conducted an experimental investigation of fatigue life of thrust chamber under cyclic thermal loading , quentmyer identified a correlation between number of cycles to failure and temperature predicted through the application of sinda ( system improved numerical differencing analyzer) software. saha extended the computer program (blimp) for boundary layer analysis to predict a thrust chamber wall temperature by coupling this analysis with regenerative process along axial nozzle cross section passing through cooling channel . the objective of the present work is to compute the temperature distribution within material of temperature dependent conductivity by utilizing finite difference method employing different space divisions in r and θ direction with special application to thrust chamber wall of rocket thrust chamber rl10 composed of multi layers and exposed to different outside and inside boundary conditions. dr. kareema e. amori /al-khwarizmi engineering journal ,vol.3, no.3, pp 1-12(2007) 2 c copper nickel soot t t ot o g o 1o cell of thrust chamber wall cooling channel hot gas (a) (b) (c) fig.(1). a).rocket thrust chamber nozzle. b )cross section through aa. c). layers of the wall theory and computational scheme the temperature distribution within thrust chamber wall can be obtained by satisfying the first law of thermodynamic combined with fourier's law of heat conduction with the assumptions: 1-steady state two dimensional heat transfer 2-temperature dependent conductivity 3no internal heat generation yields the following governing differential equation: 0)()( = ∂ ∂ ∂ ∂ + ∂ ∂ ∂ ∂ θθ tk r tr r …(1) where t : temperature (k) k : thermal conductivity (w/m.k) the interested region is divided into unequal space divisions (δr and δθ) in r and θ directions respectively as shown in fig.(2). a a toward injector hot gas in coolant in hot gas out coolant out dr. kareema e. amori /al-khwarizmi engineering journal ,vol.3, no.3, pp 1-12(2007) 3 r i r ci r co r o i , j r r 2 1r 2 1 r4 r4 r2 r2 r1r1 r3 r3 i , j-1 i , j+1 i -1, j i+1 , j i , j fig.(2): discritization of the physical domain in r-θ plane utilizing the finite difference method the temperature at each node can be computed in terms of temperature of the surrounding nodes. hence equation (1) is approximated by this mean for a middle node (i,j) shown in fig.(3) such that [ozisik1980]: fig.(3). thermal resistances around node i,j 01,,11,,1 =+++ −−++ jijijiji qqqq ….(2) where        − = − = − = − = − − − − + + + + 2 ,1, 1, ,,1 ,1 2 ,1, 1, 1 ,,1 ,1 ; 3 ; r tt q r tt q r tt q r tt q jiji ji jiji ji jiji ji jiji ji .(3) where (i,j) : indices in r and θ direction q : heat transferred in w/m r : thermal resistance (for conduction heat transfer )(*tan depthunitperareakcedisr = ) or ))(*(1 depthunitperareahr = (h is convection heat transfer coefficient hcon, or for radiation heat transfer )( 3 , 22 , 3 , tttttth jijijirad +++= εσ ) ε : emissivity factor = 0.9 σ :stefan-boltzman constant =5.669*10-8 w/m2 k4 hence equation (2) can be rewritten such that: dr. kareema e. amori /al-khwarizmi engineering journal ,vol.3, no.3, pp 1-12(2007) 4 4321 4 1, 3 ,1 2 1, 1 ,1 , 1111 rrrr r t r t r t r t t jijijiji ji +++ ++ = −−++ .……(4) where ji ji krr r krr r r rr ,21 1 ,121 1// 1 / 11 *)22( 2 *)22( 2 ∆+∆ ∆ + ∆+∆ ∆ =+= + θ θ )11( )( ,,121 1 1 jiji kkrr r r + ∆+∆ ∆ = + θ ………(5a) )2)(22( 2 )2)(22( 2 221, 2 2211, 2 // 2 / 22 rrk r rrk r r ji ji rr ∆+∆+∆ ∆ + ∆+∆+∆ ∆ = += + θθ θθ )11( ))(2/( ,,1212 2 2 jiji kkrr rr + ∆+∆∆+ ∆ = +θθ ..(5b) )22( 2 )22( 2 21, 2 21,1 2// 3 / 33 rrk r rrk r r ji ji rr ∆+∆ ∆ + ∆+∆ ∆ =+= − θ θ )11( )( ,,121 2 3 jiji kkrr rr + ∆+∆ ∆ = − θ ……….(5c) )2)(22( 2 )2)(22( 2 121, 1 1211, 1 // 4 / 44 rrk r rrk r r ji ji rr ∆−∆+∆ ∆ + ∆−∆+∆ ∆ = += − θθ θθ )11( ))(2/( ,1,211 1 4 jiji kkrr r r + ∆+∆∆− ∆ = −θθ …….(5d) where ( r ) is radius of node (i,j), and since the conductivity depends on temperature then: ( 1,,11,,1, −−++ ≠≠≠≠ jijijijiji kkkkk ). the expressions of thermal resistances for other special kind nodes are presented in appendix a: geometry and boundary conditions detailed dimensions of thrust chamber cross section employed in the present work. is given in table (1) based on [naraghi, et. al. 1987]. the left and right sides of thrust cell are assumed to be adiabatic walls, since symmetric temperature fields cross these sides (lines of symmetry). in the present study two sets of boundary conditions are analyzed: 1a convective boundary condition applied at inner radius of thrust chamber (which exposed to hot gas), and cooling channel walls ( where heat is removed from chamber wall to liquid hydrogen). free convection boundary condition at chamber outer radius which is exposed to outside environment where heat transfer coefficient at this surface is given by [holman 1981]: ( ) 25.03 2 2 1, pr)( 53.0 θ µ ρβ θ ∆ − ∆ = ∞ o ji o air conv r ttg r k h …(6) where g: gravitational acceleration m/s2 β :thermal expansion=1/t∞ (k-1) ρ :air density= 1.2 kg/m3 pr: prandtle no. for air=0.7 2-radiation boundary conditions at these surfaces are considered beside the convective boundary conditions mentioned above, heat transmitted in this case is calculated as:    += −= ∞ radconv jiji hhh tthaq )( ,, …...(7) dr. kareema e. amori /al-khwarizmi engineering journal ,vol.3, no.3, pp 1-12(2007) 5 the specifications of fluids surrounding the thrust cell with convective heat transfer coefficients employed are presented in table (1). computational algorithm 1-assume initial nodal’s temperature such that: 3/)( 1, ∞∞ ++= tttt cgji …….(8) 2compute thermal conductivity of each node based on its temperature by employing linear interpolation to the data given in fig.(4). 3-compute nodal’s temperature value which is given by       = ∑∑ == 4 1 4 1 , /1/)( k kk k kji n rrtt ….(9) for nodes located at the insulated sides (k=1→ 3). iterative successive method with under relaxation factor (ω=0.9) has been used 4-the iterations are terminated according to the following convergence criterion. 7 ,,, 10/)( −≤− ji n jiji n ttt …...(10) where n refers to new temperature value. 4-calculate heat transferred from hot gas, to coolant, and to outside of thrust wall cell applying: )( 1 kg k kig ttahq −= ∞ = ∑ )( 1 ck k kcc ttahq −= ∑ = …(11) )( 1 1 ∞ = −= ∑ ttahq k k koo results and discussion figure (5) presents radial temperature distribution within thrust wall cell (for cooling channel aspect ratio (ar=8.25) (which is the ratio of cooling channel height to width) when only convection boundary condition is considered ) for different selected lines (from a-a to h-h ). highest temperature values indicated at lines located far from cooling channel, while the coldest lines are those pass through it due to cooling process. also it is clear that temperature values are decreasing toward outside wall surface lines (aa to dd), this is agreed well with the results of (naraghi 2001). parametric study 1-effect of cooling channel aspect ratio figures (6) and (7) show temperature profile at lines aa and hh respectively for different aspect ratios. it is clearly indicated that the nodes at lines aa and hh (belong to region below cooling channel) have the highest temperature values for (ar=2.5) compared with other (ar) values while the lowest temperature is indicated for (ar=8.25) for the same nodes. this is due to increas in the cooling channel width for the same height for (ar=2.5) which leads to increase in the surface area of heat transfer to coolant. this results is agreed with [naraghi 2001] for utilizing high aspect ratio cooling channel design. figure (8) shows clearly that temperature profile at cooling channel wall for (ar=8.25) is preferred since no large variations exist where the subscript k refers to element indices that belong to either high temperature wall or cooling channel wall or thrust cell outer wall. 5verify that qg+ qc+ qo=0.0 2-effect of radiation boundary condition in order to show the effects of radiation heat transfer on the wall temperature of cooled rocket thrust chamber, conjugated boundary conditions (radiative and convective) dr. kareema e. amori /al-khwarizmi engineering journal ,vol.3, no.3, pp 1-12(2007) 6 have been applied at inner surface, cooling channel wall and outside surface. figure (9) shows the temperature profiles for selected lines aa and ee, which indicate higher temperature values when radiation is considered. figure (10) shows lower temperature values at coolant channel wall when combined radiation convection heat transfer is applied. it is deduced form fig.(11) that larger heat is transferred from thrust chamber wall to coolant when radiation heat transfer is considered while no effect of aspect ratio is indicated . conclusions the effects of cooling channel aspect ratio and radiation boundary condition on thermal characteristics of thrust chamber wall are studied. it was found that utilizing cooling channels of high aspect ratio leads to decrease in the temperature variation across thrust chamber wall, while no effects on heat transferred to the coolant. the radiation has a considerable effect on the wall temperature value. references: armstrong, w.h. and brognen, e.w., (1975), " thrust chamber life prediction volume ii plug nozzle centerbody and cylinder life analysis", nasa cr 143822 arya, v.k. and arnold, s. m. , (1991), "viscoplastic analysis of an experimental cylindrical thrust chamber liner", nasa tm 103287 butler d. t. and pindera, m-j. (2004) “analysis of factors affecting the performance of rlv thrust cell liners", nasa/cr-2004-213141 holman, j.p. ;(1981) ;”heat transfer”, fifth edition, mcgraw-hill book company kacynski, k. j. (1992),"thermal stratification potential in rocket engine coolant channels", nasa tm 4378 naraghi, m. h.(1987),”a twodimensional thermal analysis of rocket thrust chambers” nasa-tm100191 naraghi, m. h.;quentmyer, r. j.;mohr, d. h.(2001),”effect of a blocked channel on the wall temperature of a regeneratively cooled rocket thrust chamber” aiaa 2001-3406 ozisik, h. h. (1980), " heat conduction" john wiley & sons,1980 saha, h. (1976), " rocket engine thrust chamber wall temperature distribution calculation and analysis", nasa nsg-8022 dr. kareema e. amori /al-khwarizmi engineering journal ,vol.3, no.3, pp 1-12(2007) 7 a b c d e f g h hf e dcba g table (1):data employed in computer program run [naraghi 1987] 200 400 600 800 1000 1200 1400 1600 1800 temperature (k) 0 10 20 30 40 50 60 70 80 90 100 110 120 n ic ke l k (w /m .k ) 0 50 100 150 200 250 300 350 400 450 c up pe r k (w /m .k ) nickel cupper fig. (4): thermal conductivity of cupper and nickel [kacynski] 0.88 0.90 0.92 0.94 0.96 0.98 1.00 r/ro 50 52 54 56 58 60 62 64 66 68 70 72 74 76 te m pe ra tu re (k ) line a-a line a-a line b-b line c-c line d-d line e-e line g-g line h-h (a) (b) fig.(5):a). selected lines through thrust cell. b). radial temperature distribution of thrust chamber cell for (ar=8.25 ) hot gas temperature (2655 k ) hot gas heat transfer coefficient (w/m2k ) (290) coolant temperature (50 k) coolant heat transfer coefficient (w/m2k ) (15290.65) outside temperature (294 k) no. of cooling channels (100) thrust chamber inner radius ri (44.44 mm ) thrust chamber outer radius ro (49.675 mm) cooling channel inner radius rci (44.95 mm) cooling channel height h (4.2144 mm cooling channel width based on rci (0.511 mm) dr. kareema e. amori /al-khwarizmi engineering journal ,vol.3, no.3, pp 1-12(2007) 8 fig.(6): aspect ratio effect on temperature distribution along line a-a( only convection boundary condition) 0.988 0.990 0.992 0.994 0.996 0.998 1.000 r/ro 50 52 54 56 58 60 62 64 66 te m pe ra tu re (k ) ar=8.25 ar=6 ar=5 ar=2.5 0.894 0.895 0.896 0.897 0.898 0.899 0.900 0.901 0.902 0.903 r/ro 72.5 73.0 73.5 74.0 74.5 75.0 te m pe ra tu re (k ) ar=8.25 ar=6.5 ar=5 ar=2.5 ( a) (b) fig.(7): aspect ratio effect on temperature distribution along line h-h . a) wall region over the cooling channel b) wall region below the cooling channel 0.88 0.90 0.92 0.94 0.96 0.98 1.00 r/ro 56 58 60 62 64 66 68 70 72 74 76 te m pe ra tu re (k ) ar=8 ar=6.5 ar=5 ar=2.5 dr. kareema e. amori /al-khwarizmi engineering journal ,vol.3, no.3, pp 1-12(2007) 9 cooling channel 39 8 7 5 4 123 6 10 12 0 1 2 3 4 5 6 7 8 9 10 11 12 node no. 55 65 75 85 95 105 te m pe ra tu re (k ) ar=8.25 ar=6.5 ar=5 ar=2 (a) (b) fig.(8):a). nodes numbering of cooling channel wall b). effect of aspect ratio on cooling channel wall temperature profile (only convection boundary condition) 0.88 0.90 0.92 0.94 0.96 0.98 1.00 r/ro 65 70 75 80 85 90 95 100 105 te m pe ra tu re (k ) a-a conv e-e conv. a-a rad. e-e rad. fig.(9): temperature distribution along line a-a and e-e for radiation and convection boundary conditions dr. kareema e. amori /al-khwarizmi engineering journal ,vol.3, no.3, pp 1-12(2007) 10 cooling channel 39 8 7 5 4 123 6 10 12 1 2 3 4 5 6 7 8 9 10 11 12 node no. 75 80 85 90 95 100 te m pe ra tu re (k ) conv. and rad. conv. fig.(10): a). nodes numbering of cooling channel wall. b) temperature distribution along cooling channel wall 0 1 2 3 4 5 6 7 8 9 10 0 20 40 60 80 100 120 140 160 180 200 220 he at (w /m ) conv. rad. and conv. ar fig.(11 ): aspect ratio effect on heat transferred from hot gas wall for convection and combined convection radiation boundary condition dr. kareema e. amori /al-khwarizmi engineering journal ,vol.3, no.3, pp 1-12(2007) 11 appendix thermal resistance of nodes belong to the interfacial line between two different materials a and b as shown in fig.(a1) can be written as: ) )( 1 )( 1(* )( )( ,1,21 1 1 ajiaji a kkrr r r + + ∆+∆ ∆ = θ .. (a1) ) )( 1 )( 1( )( )( ,,121 1 1 bjibji b kkrr r r + ∆+∆ ∆ = + θ ..(a2) ba ba rr rrr )()( )()( 11 11 1 + = ………….(a3) substituting equations (a1) and (a2) in (a3) yields: )11( ))(2/( ,,1212 1 1 jiji kkrr rr + ∆+∆∆+ ∆ = +θθ θ ……..(a4) )22( 2 )22( 2 21, 2 21,1 2 // 3 / 33 rrk r rrk r r jiji rr ∆+∆ ∆ + ∆+∆ ∆ = += − θθ )11( )( ,,121 2 3 jiji kkrr rr + ∆+∆ ∆ = − θ ….(a5) )2)(22( 2 )2)(22( 2 121, 1 1211, 1 // 4 / 44 rrk r rrk r r ji ji rr ∆−∆+∆ ∆ + ∆−∆+∆ ∆ = += − θθ θθ )11( ))(2/( ,1,211 1 4 jiji kkrr r r + ∆+∆∆− ∆ = −θθ …….(a6) the thermal resistance of nodes belong to surface exposed to fluid of t∞1 as shown in fig.(a2) can be written as: )()( 111 rrr ′′+′= ……(a7) 2/)(** 1 21 2 θθ ∆+∆ = rh r …….(a8) )()( 333 rrr ′′+′= ……….(a9) )()( 444 rrr ′′+′= ……..(a10) fig.(a1 ): thermal resistances around node (i,j) located at interfacial line fig.(a2 ): thermal resistances around node (i,j) located at surface exposed to environment b a r3 r3 1 r1r1 i+1 , j i -1, j i , j+1 i , j-1 r3 r3 r1 r1 r2 r2 r4 r4 2 r 1 2rr i , j 1oot i , j i+1 , j i -1, j i , j-1 r3 r3 r1 r1 r2 r4 r4 1 2 2r r i , j dr. kareema e. amori /al-khwarizmi engineering journal ,vol.3, no.3, pp 1-12(2007) 12 راري لجدران غرفة الدفع بوجود مجاري التبریددراسة متغیرات السلوك الح كریمة اسماعیل عموري . د قسم الھندسة المیكانیكیة/ كلیة الھندسة/ جامعة بغداد الخالصة وأستخدم معام ل (بأستخدام طریقة الفروقات المحددة التكراریة ) rl10(تم أجراء تحلیل حراري ثنائي البعد لجدار غرفة الدفع لصاروخ والذي یتكون من طبقة النیكل وأخ رى (ألستحصال توزیع درجات الحرارة خالل الجدار ) لغرض تسریع الوصول الى الحل ٠.٩تخمید ال ولق یم مختلف ة , ثم نقل حرارة باألشعاع والحمل معا, نقل حرارة بالحمل فقط , أجریت الدراسة بتطبیق ظروف حدیة متعددة ). من النحاس بینت النتائج أن أستخدام مجرى تبرید ذو نس بة باعی ة عالی ة یول د توزی ع ح راري ذو تغی رات أق ل . لمجرى التبرید) ar( من النسبة الباعیة بین ت النت ائج أن ھ ال یمك ن اھم ال ت أثیر . في حین ال تتأثر كمیة الحرارة المنتقل ة ال ى م ادة التبری د بتغیی ر النس بة الباعی ة , على مدى الجدار . األشعاع الحراري <4d6963726f736f667420576f7264202d20edc7d3e3ede420e6dac7d5e320e6dae1c7c13130372d313135> al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 14, no.2, june, (2018) p.p. 107115 cellulose fibers dissolution in alkaline solution yasmeen salih mahdi* asem hassan mohammed** alaa kareem mohammed*** *,***department of biochemical engineering/ al-khwarizmi engineering college/ university of baghdad ** institute of technology baghdad/ chemical industries/ middle technical university *email: yasmeensalih90@gmail.com **email: asemh2005@yahoo.com ***email: alaauniv@yahoo.com (received 3 october 2017; accepted 14 november 2017) https://doi.org/10.22153/kej.2018.11.005 abstract in this study, naoh dissolution method was applied to dissolve cellulose fibers which extracted from date palm fronds (type al-zahdi) taken from iraqi gardens. in this process, (naoh)-solution is brought into contact with the cellulose fibers at low temperature. experiments were conducted with different concentrations of naoh (4%, 6%, 8% and12%) weight percent at two cooling bath temperatures (-15 oc) and (-20oc). maximum cellulose dissolution was 23 wt% which obtained at 8 wt% concentration of naoh and at cooling bath temperature of -20oc. in order to enhance the cellulose fibers dissolution, the sample was pretreated with fenton's reagent which consists of hydrogen peroxide (h2o2), oxalic acid (c2h2o4) and ferrous sulfate (feso4). this reagent reacts with cellulose fibers and produces free radicals which increase cellulose dissolution. in this work three variables were studied: cooling bath temperature (15ocand-20oc), naoh concentration (4%, 6%, 8% and12%) and time of fenton's reagent treatment (1-48) hrs. the results showed that the best percent of cellulose dissolution was (42 wt %) which occurred at treatment time (24 hours), temperature (-20oc) and naoh concentration 8%. in another set of experiments urea was added to naoh solution as a catalyst with proportion (6%naoh+4% urea) at two temperatures -15 and -20 oc. the results show that the solubility of cellulose increase to 62% for the sample which treated with fenton's reagent and to 35% for the untreated sample, both values were obtained at -15oc. keyword: dissolution of cellulose, cellulose fibers, fenton's reaction. 1. introduction dissolution of cellulose is a kinetic process where the forces that maintain the crystalline structure are overcome and lead to the disintegration of the structure into molecules [1]. the forces include the hydrogen bonds within the chain (intramolecular) and between the neighboring chains (intermolecular), as well as the van der waals forces and hydrophobic forces. the dissolution occurs when such a solvent is introduced to polymer which is able to disturb the mutual interaction of the polymer molecules [2]. cellulose is a linear, semi-flexible polymer that is self-organized in crystalline and noncrystalline phases. since cellulose cannot melt, dissolution is a major issue. cellulose solutions are used for processing cellulose in the form of fibers, films, membranes or other not too bulky objects such as sponges or aerogels, or for performing chemical derivatisation. since cellulose chains have no specific features, the cellulose must be dissolved as occur to any other flexible or semi-flexible polymer, and cellulose solutions should behave as normal polymer solutions [3]. the development of cellulose dissolution/regeneration strategies constitutes an increasingly active research field. these are fundamental ways of several production processes yasmeen salih mahdi al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 107115 (2018) 108 and applications. a wide range of appropriate solvents for cellulose is already available. however, most solvent systems have significant limitations, and there is intensive activity in both industrial and academic research aimed at improving existing solvents and developing new ones. cellulose solvents have very different nature which gives great challenges in understanding the delicate balance between different interactions [4]. previously, several traditional solvent systems were introduced. one of the famous methods to dissolve cellulose was cs2 method (viscose type), which was the oldest and complex procedure for producing rayon [5]. in this way, a prior chemical modification of the molecules was needed, leading to serious environmental pollution and poor human health. consequently, due to these defects, non-derivative solvent systems are more acceptable were used, inclusive ammonium fluorides /dimethylsulfoxide (dmso), n, ndimethylacetamide/ lithium chloride (dmac/licl), and also n-methyl-morpholine-noxide (nmmo) [6]. these three solvents accumulate with a several structure and are thought to dissolve the cellulose without breaking any existing chemical bonds. another solvent is sodium hydroxide used to dissolve cellulose, recently the main focus was placed on the aqueous alkaline solvents due to consideration of being inexpensive, harmless and ecofriendly, so sodium hydroxide can be regarded as the most suitable solvent for cellulose dissolution [7]. the purpose of the current study is to dissolve cellulose which extracted from date palm fronds after treated it with fenton's reagent and sodium hydroxide solution with and without urea under controlled conditions. 2. experimental work in order to carry out dissolution process of cellulose fibers, several steps must be conducted. first, the quantitative analysis of date palm frond was done to identify the cellulose content in the fronds. secondly, the sample was delignificated using modified organosolv to remove lignin from biomass (date palm fronds). in the third step the sample was bleached to remove most of the remaining lignin and hence increasing cellulose content to about 96%). the last step includes dissolving cellulose fibers using naoh solution with and without urea. 2.1 compositional analysis of data palm fronds the samples of date palm fronds were collected in the summer season from babylon farms from a kind of date palm named (al-zahdi) and stored in presterilized bags in refrigerator freeze. the samples then taken to the laboratory for test and before being treated, impurities should be removed by washing them with distilled water several times .after that, the samples were shredded using electric cutter and crushed with humor then sieved. fragments with a particle size of (270-90) μm were selected to be used in the next steps [8]. table (1) shows the composition of fronds (leaves and stalk). table 1, the composition of date palm fronds (leaves and stalk) based on dry weight wt/wt sample carbohydrate lignin ash extractive protein leaves 52 26 8 10 4 stalks 59 23 7 8 3 2.2 delignification lab scale experiments were performed in two liter autoclave batch reactor. the date palm fronds (biomass) were milled to about 0.18mm. a suspension of biomass-water-organic solvent (ethanol) was made (typically, 200 ml solvent per 20 g biomass). the experimental parameters in the delignification process were: temperature, ethanol /water ratio wt/wt and digestion time. from previous study, the optimum conditions for delignification process were: temperature 185oc, ethanol: water 50:50 and digestion time 80 min [9]. in order to reduce the digestion time, three types of catalyst were tested: h2so4, naoh and ca (oh) 2. among them, sodium hydroxide (0.025m) was found the best one which reduces the time from 80 min to 30 min. the aim of delignification, is to remove lignin and hemicellulose and obtain pure cellulose [10]. 2.3 bleaching bleaching is a chemical treatment performed to different types of wood pulp to remove pulp color so that it becomes whiter. the objective of yasmeen salih mahdi al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 107115 (2018) 109 chemical bleaching of the pulp is basically to remove all of the remaining lignin. so the process is often referred to as delignification [11]. chlorine is the basis for the most common bleaching processes. three grams of dried sample was weighted and put into 500 ml flask, then 250ml of sodium chlorite solution (60 gm per liter sodium acetate and 60 gm per liter sodium chlorite) was added, the sample was then soaked for four days[12]. after that it was washed with deionized water, followed by extraction with naoh (0.15 n) several times and then it was washed with hypochlorite and distilled water. finally, the sample was dried. it was noted that the color was changed from dark brown to white (this means eliminating the lignin and the remaining was mainly cellulose as shown in figure (1). fig. 1. the sample after bleaching. 2.4 fenton's reagent fenton's reagent is a solution consists of hydrogen peroxide with ferrous iron as a catalyst that is used to oxidize contaminants or waste waters. it was developed in the 1890s by henry john horstman fenton as an analytical reagent. the traditional fenton reaction is the catalyzed decomposition of dilute hydrogen peroxide (h2o2) by iron (ii) to form radicals of hydroxyl. h2o2 + fe2+ → fe3++ •oh + −oh 2.4.1 fenton's reagent preparation fenton's reagent can be prepared by mixing: (80mm h2o2, 0.5mm feso4, 10mm oxalic acid, 10mm sodium oxalate), mixing between oxalic acid and sodium oxalate was according to the following volume ratio: (1:13) to reach ph= 4.6-5 [13]. 2.5 cellulose dissolution procedure 1. solutions of sodium hydroxide were prepared with different concentrations (6%, 8%, 10% and 12%) weight percent. for example to prepare 6% wt, 6 g of naoh is completed to 100 ml by adding 94g distilled water [14]. 2. the sample which bleached before was treated with fenton's reagent by taking 0.2 g of the sample (mainly cellulose) with 10 ml reagent. then placed in a plastic container (30 ml volume) and stirred for 24 hrs using magnetic stirrer [15]. after that the sample was washed with deionized water and dried for 8 hours at 50oc. figure (2) shows the sample after treatment with fenton's reagent. fig. 2. the sample after treatment with fenton's reagent. 3. the treated sample was placed in a test tube and 10 ml of naoh solution was added. 4. the sample was left for 1 hr, and then placed in a plastic container which contains ethyl glycol (38%) and put in freezer for 24 hrs. 5. the sample was removed from the freezer and left for at least one hour at room temperature to melt it. 6. then the sample was centrifuged at 2500 rpm to separate the dissolved fibers from those which undissolved. 7. undissolved fibers were washed with distilled water and weighted to calculate dissolution percent as in eqn. (1). cellulose dissolution% weight of cellulose������ ���������weight of cellulose����� �������� !"#$% &' cellulose������ �������� ∗ 100 …(1) yasmeen salih mahdi al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 107115 (2018) 110 8. the dissolved fibers were injected in 10 % dilute sulphuric acid to form rayon, as shown in figure (3). fig. 3. synthesis of rayon (regenerated cellulose). 3. results and discussion 3.1 cellulose dissolution three parameters were studied in the dissolution process; sodium hydroxide concentration, path cooling temperature and fenton's reaction time. the ranges of these parameters were (4 %-12%) weight percent, two temperatures (-15 and -20) oc and (1-48) hours respectively. two types of samples were used; sample was treated with reagent and a sample without treatment. experiments were repeated four times and average values of cellulose dissolution were taken. 3.1.1 effect of fenton's reaction treatment to study the effect of fenton's reagent use on cellulose dissolution, several values of fenton's reaction time were studied within the range (1-24) hr. fenton's reaction produces radicals which break the hydrogen bonds for cellulose and make it ready to dissolve in naoh solution. from fig. (4) it was concluded that cellulose dissolution increased with increasing time until time 24 hr, beyond which the solubility of cellulose fibers begin to decrease. this is because the structure of cellulose fibers distorted and leads to decrease dissolution of cellulose fibers. the optimum value of cellulose dissolution was 30 wt % which occurred at reaction time 24hr. budtova and navard (2016) studied the dissolution of cellulose fibers for cotton and found that the perfect fenton's reaction time was 18 hr. to give maximum cellulose dissolution of 23%. fig. 4. effect of fenton's reagent duration on cellulose dissolution. 3.1.2 effect of naoh concentration to study the effect of alkaline concentration for cellulose dissolving, four values of concentration were taken (4%, 6 %, 8 % and 12 wt %). two sets of experiments were conducted. in the first set, the samples were treated with fenton's reagent for 24 hr. while in the second set the samples were untreated. fig (5) shows that for both sets at (15oc) , the best value of naoh concentration was 8% which causes cellulose dissolution of 30 wt% for samples which treated with fenton's agent and 23% for samples which untreated. wang (2008) was studied cellulose dissolution for cotton linter (as a cellulose fibers source) using naoh solution with different concentrations and different cooling bath temperatures and found that the best cellulose dissolution percent was 20 wt% when using 9 wt% naoh concentration. yasmeen salih mahdi al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 107115 (2018) 111 fig. 5. percentage of cellulose dissolution at different naoh weight concentrations at temperature 15 ±2oc. the same two sets of experiments were conducted at -20oc. figure(6) shows that the best cellulose dissolution for sample which treated with fenton's reagent was 42% which occurred also at 8% naoh concentration while for untreated sample the maximum cellulose fibers dissolution was 28% this implies that decreasing the temperature to -20oc will enhance the solubility of cellulose in naoh solution. fig. 6. percentage of cellulose dissolution at different naoh weight concentrations at temperature -20 ±2oc. from figures (5and 6), it was concluded that the best naoh concentration for cellulose dissolution process was 8%. furthermore, the samples which treated with fenton's reagent show better dissolution in naoh solution than those which untreated. figure 7 illustrates how the hydrodynamic of hydrate ions was affected by the concentration of ion solution. at low solution concentration, the ions are surrounded by a large amount of water molecules and thus pairs of separated ions are existing. at high solution concentration, the ions will be surrounded by fewer amounts of water molecules resulting in lower hydrodynamic diameter. the cellulose crystallite diameter is 10 nm and inter-sheet distance is of about10 ȧ [17]. at low concentration of naoh, the hydrodynamic diameter is too large to penetrate cellulose crystalline region, while at high naoh concentration the hydration of naoh will be insufficient to break hydrogen bonding which makes the cellulose to mercerize (not dissolved). therefore; there is a certain concentration of naoh solution which is appropriate to penetrate the cellulose and start to dissolution. this value of concentration is called turn point concentration (critical concentration) [18]. in the current study, it was found that the turn point concentration was 8%. this finding is agreement with that found by wang (2008) who found that the turn point concentration of cellulose (cotton linter) was 9%. fig. 7. hydrodynamic diameter of hydrates with respect to naoh solution concentration [19]. 3.1.3 effect of temperature with a view to study the effect of temperature on solubility of cellulose fiber, two values of temperatures were used (-15 oc and -20 oc) depending on previous studies [20] [21]. figure (8) shows that at -20 oc, the best cellulose dissolution for sample which treated with fenton's reagent was 42% and for untreated sample the maximum cellulose fibers dissolution was 28%. while at temperature (-15oc), the cellulose dissolution percent was 30 % for treated sample and 23% for untreated sample. this implies that decreasing temperature to (-20 oc) will enhance the solubility of the cellulose in naoh solution. yasmeen salih mahdi al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 107115 (2018) 112 fig. 8. effect of temperature on cellulose dissolution at 8% alkaline solution. the explanation the effect of temperature on the solubility of cellulose will be in the next section. 3.1.4 effect of urea addition the effect of adding urea to naoh solution on cellulose fibers dissolution was studied, a solution of naoh and urea with proportion (6%naoh and 4% urea) was used to enhance cellulose fibers dissolution or stimulate crystalline polymerization [17].figure (9) shows that at temperature -15oc the maximum cellulose fibers dissolution was 62% for the samples which treated with fenton's reagent and 35% for untreated. figure (10) shows the results of cellulose dissolution at temperature 20oc. for the sample which treated with fenton's reagent the maximum cellulose fibers dissolution was 35% while for an untreated sample was 28%. these results for treated samples indicate that adding urea will increase the solubility from 30% to 62% at (-15oc) while at (-20oc) adding urea will decrease the cellulose fibers dissolution from 42% to 35%. fig. 9. effect of urea addition on cellulose dissolution at temperature 15 ±2oc. fig. 10. effect of urea addition on cellulose dissolution at temperature -20 ±2oc. the cellulose fibers dissolution is a thermodynamic process and can be represented by gibbs free energy equation: ∆g = ∆h – t. ∆s … (1) for cellulose dissolution process (breaking cellulose crystal) by naoh solution without urea, values of entropy and enthalpy change are -2.23 kj /mol k and -495.48 kj /mol respectively. while for the treatment with naoh and urea, values are -0.546 kj /mol k and -61.83 kj /mol respectively [22]. at temperature 258 k (-15oc), ∆g=80.55 kj /mol for treatment without urea and ∆g=79.01 kj /mol for treatment with urea. the decrystallization reaction is exothermic because of the negative value of enthalpy so lower temperature is favorable. figure 11 shows the plot of gibbs free energy verses temperature for dissolution of cellulose by naoh solution with and without urea. the two straight lines intersect at temperature 258k (-15oc). at temperature greater than 258k (-15oc), the treatment with naoh and urea solution has lower ∆g than that without urea which is better for decrystallization reaction. while at temperatures less than 258k (-15oc) naoh without urea has lower ∆g so it is better for decrystallization. in the current study the lowest temperature was 253k (-20oc). yasmeen salih mahdi al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 107115 (2018) 113 fig. 11. gibbs free energy for cellulose dissolution by naoh with and without urea [16]. 4. conclusion based upon the results obtained so far, there is a possibility to dissolve the cellulose which extracted from the date palm fronds using naoh solution method. the more effective parameters in the cellulose fibers dissolution process were: cooling bath temperature, naoh concentration and time of fenton's reagent treatment. the best naoh concentration for cellulose fibers dissolution was 8 wt% at -20oc at which the dissolution of cellulose reaches 42% when the samples were treated with fenton's reagent for 24 hr, while for samples untreated with fenton's reagent the dissolution reaches 28%. adding urea to naoh solution (6%naoh and 4% urea) was found to increase the cellulose dissolution to 62% at temperature -15oc for samples which treated with fenton's reagent for 24 hr. 5. reference [1] t. budtova and p. navard, “cellulose in naoh–water based solvents: a review,” cellulose, vol. 23, no. 1, pp. 5–55, 2016. 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[22] m. kihlman, b. f. medronho, a. l. romano, u. germgård, and b. lindman, “cellulose dissolution in an alkali based solvent: influence of additives and pretreatments,” j. braz. chem. soc., vol. 24, no. 2, pp. 295– 303, 2013. )2018( 107-115، صفحة 2د، العد14دجلة الخوارزمي الهندسية المجلمياسمين صالح مهدي 115 أذابة ألياف السيليلوز في المحاليل القاعدية **عالء كريم محمد* عاصم حسن محمد** ياسمين صالح مهدي* جامعة بغداد قسم الهندسة الكيميائية االحيائية/ كلية الهندسة الخوارزمي/*** ،* الكيمياوية/ الجامعة التقنية الوسطىقسم الصناعات ** معهد التكنولوجيا بغداد/ gmail.com90yasmeensalih@ البريد االلكتروني:* asemh2005@yahoo.com:البريد االلكتروني * alaauniv@yahoo.com:البريد االلكتروني *** الخالصة المزارعمن سعف النخيل (نوع الزهدي) المأخوذ من ةفي هذه الدراسة، تم أستخدام محلول هيدروكسيد الصوديوم ألذابة األلياف السليلوزية المستخلص وزنية ريت التجربة مع تراكيز، يتم تفاعل محلول هيدروكسيد الصوديوم مع ألياف السليلوز في درجات حرارة منخفضة. أجعملية االذابةالعراقية. في درجة مئوية. كان الحد األقصى لذوبانية السليلوز ٢٠ -درجة مئوية و ١٥ -٪) في درجتين حرارية ١٢و ٪٨، ٪٦، ٪٤مختلفة من هيدروكسيد الصوديوم ( ة مئوية. من أجل تعزيزذوبانية ألياف درج٢٠-٪ من هيدروكسيد الصوديوم وفي درجة حرارة ٨٪ نسبة وزنية وقد تم الحصول عليها عند تركيز ٢٣هي ) وكبريتات الحديد الثنائية 4o2h2c) وحامض األوكساليك (2o2hالسليلوز ، تم معالجة النموذج مع كاشف فينتون الذي يتكون من بيروكسيد الهيدروجين ( )4feso درجة تم دراسة ثالثة متغيرات وهي). يتفاعل هذا الكاشف مع ألياف السليلوز لينتج الجذور الحرة التي تزيد من ذوبان السليلوز. في هذه الحالة هرت ) ساعة. وأظ٤٨-١٪) ووقت المعالجة بكاشف فينتون (١٢و ٪٨، ٪٦، ٪٤) درجة مئوية، تركيز هيدروكسيد الصوديوم (٢٠-و ١٥-الحرارة عند ( ٪. في ٨درجة مئوية) وتركيز هيدروكسيد الصوديوم ٢٠-ساعة) ، درجة حرارة ( ٢٤) عند زمن معالجة (٪٤٢النتائج أن أفضل نسبة لذوبانية السليلوزهي ( يوريا) عند ٪ ال٤هيدروكسيد الصوديوم + ٪٦بنسبة ( بوصفه محفزامجموعة أخرى من التجارب تمت إضافة اليوريا إلى محلول هيدروكسيد الصوديوم ٪ ٣٥و٪ للنموذج الذي تم معاملته مع كاشف فنتون ٦٢إلى ز تزداد) درجة مئوية. أظهرت النتائج أن ذوبانية السليلو٢٠-و ١٥-درجتين حرارية هي ( درجة مئوية.١٥-تم الحصول عليها عند درجة حرارة القيمتين لذوبانية السيليلوزلتا للنموذج غير المعالج، وك (microsoft word \330\307\341\310 \346\332\341\355 \315\343\322\311 34-43) al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 15, no. 2, june , (2019) p.p. 3443 mesoporous silica mcm-41 as a carriers material for nystatine drug in delivery system talib m. albayati* ali m. alkafajy** *،** department of chemical engineering/ university of technology/ baghdad /iraq *email: talib_albyati@yahoo.com **email: alkafagae1986@yahoo.com (received 7 october 2018; accepted 4 november 2018) https://doi.org/10.22153/kej.2019.11.003 abstract in the present study, mcm-41 was synthesis as a carrier for poorly drugs soluble in water, by the sol-gel technique. textural and chemical characterizations of mcm-41 were carried out by x-ray diffraction (xrd), fourier transform infrared (ftir), scanning electron microscope (sem), and thermal gravimetric analysis (tga). the experimental results were analyzed mesoporous carriers mcm-41. with maximum drug loading efficiency in mcm-41 determined to be 90.74%. the nys released was prudently studied in simulated body fluid (sbf) ph 7.4 and the results proved that the release of nys from mcm-41 was (87.79%) after 18 hr. the data of nys released was found to be submitted a weibull model with a correlation coefficient of (0.995). the historical data experimental design facilitated the formulation and optimization of sustained discover the optimal formulation to loading drug, combine process variables, mixture components and categorical factors in one design. keywords: mcm-41 silica, nystatine, adsorption, drug delivery, release systems. 1. introduction oral delivery is the favored route of medication management, but is often hampered by some challenges such as inadequate physical, biopharmaceuticals, many existing pharmaceuticals suffer from poor water solubility and/or physiological properties, resulting in inadequate solubility and bioavailability by oral [1-2]. during the past decades, porous silica has been used with many attractive properties widely in biomedical applications and drug delivery scale materials for effective oral delivery of poorly soluble drugs [3]. in addition to widely studied organic and inorganic polymers,micro-and nano porous material have attracted considerable attention recently because they are widely used as controlled delivery systems for controlled drugs and lowering the drug concentrations to be transported by employing nanostructure based on drug delivery vehicles with enhanced adsorption capability and controlled drug release properties can improve the drug’s efficiency [4-5]. the applications of mesoporous silica nanoparticles (msns) in pharmaceuticals are increasing day by day and are receiving careful attention (since the discovery of mesoporous silica materials in the 1990s, the synthesis and applications of (msns) have received substantial attention because their highly porosity, high surface area, tunable pores, non-cytotoxic properties, and well-ordered structure, well-defined surface properties and high loading and easy control of release, mesoporous materials seem ideal carrier's drugs[6]. the mesoporous has a uniform and adjustable pore size of (2–50) nm, in covenant with (iupac) "the international union of pure and applied chemistry commendation"[7]. among these mesoporous silica ''mobil composition of matter number 41 (mcm-41)'' that pore diameter (2 nm < dap< 6 nm) [8] and ''santa barbara amorphous number 15 (sba-15)'' with pore diameter (4 nm < talib m. albayati al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 3443 (2019) 35 dap< 13 nm) [9] with a two-dimensional hexagonal arrangement of cylindrical pores of a uniform size are amongst the most common investigated mesoporous materials. mcm-41 is a widely researched type of msns for drug delivery [1011]. mcm-41, it has unidirectional and very uniform channel structures from medium hexagonal pores with pore size distributions are very narrow with cylindrical ordered hexagonal mesopores structure, was firstly synthesized in a highly acidic media using amphiphilic tri-block co-polymer of "cetyl-trimethyl-ammoniumbromide (ctab)" as template in 1992 [9-12]. the loading and releasing of drugs by the (msns) is dependent on factors such as the surface chemical nature, size of pore, specific surface area and morphology of mesoporous silica [13-14]. experimental design has been used for several decades in science that provides specific information experiments, the factors really influencing was determined and see whether the effects of certain factors depend on other factors. the effect factors were taking into account possible interaction between factors. use this program to help optimize process, achieve optimal performance, discover the optimal formulation, combine process variables, mixture components and categorical factors in one design. the two parameters that studied (concentration and time) and the response was insert as group and decide the optimal parameter theoretical and experimental and studied the more effect parameter [15]. in this work preparation and characterization of mcm-41 and used for the loading of nystatine (nys), and select the best operating conditions for the different studied parameters of loading (concentration of drug and contact time) and the release of (nys) in simulated body fluid (sbf) ph 7.4. nystatin (nys) chemically ''tetraene diene polyene macrolide'' (c47h75no17) shown in fig.1. it's possesses different hydrophilic and lipophilic moieties: the hydrophilic area is composed of alcohols, carboxylic acid, and sugar whereas the lipophilic one consists of a chromophore of six conjugated double bonds [16]. nystatin (nys) is commonly employed to treat fungal infections in hiv-infected, it's used orally, but a disadvantage of these formulations is the limited residence time of it's in the affected areas [17]. the dosage form needs to reside at the site of infection for a prolonged period. these limitations can be overcome by a drug delivery system because of portability, convenient application, long retention time, easy storage and handling and improved stability [18]. fig. 1. the 2d structure of nys. 2. experimental 2.1 chemicals nystatine was purchased from al kindi company for pharmaceutical industries in iraq. cetyl trimethy ammonium bromide ch3(ch2)15n(br) (ch3)3, (ctab, 99%) with mwt. 364.45 g/mol and tetra-ethyl-orthosilicate (teos, 98%) were obtained from sigma chemicals. hydrochloric acid, potassium dihydrogen phosphate (kh2po4, 99.5%, mwt 136.2) and potassium hydrogen phosphate (k2hpo4, 98%, mwt 178.3) were purchased from cdh india. 2.2 preparation of mesoporous mcm-41 the mesoporous mcm-41 was purely synthesized according to the literature using sio2 under basic conditions and ctab, aldrich as a structural directing agent [9-12] and (teos) was used as silica precursor. first, prepare a mixture containing naoh with a weight of 0.35 g and 30 ml of distillate water, dissolve 1.01 g of ctab in solution. then, added 5.78 g of toes to the mixture drop by drop, under 1h of stirring at room ambient temperature. the homogeneous mixture output was crystallized under constant hydrothermal temperature (110 ° c) in the 96 hour in in autoclave device. the solid product obtained by filtration was washed using distill water to remove the micro-surface agent. the solid material obtained at 40 ° c was then dried overnight and the calcination was performed at 550 ° c for 6 hours to remove the surface agent, mold, and mcm-41 was obtained as show in fig. 2. [20]. talib m. albayati al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 3443 (2019) 36 fig. 2. scheme of synthesis the mcm-41. 2.3 characterization the x-ray diffraction patterns for the mesoporous sample were used to show the crystalline structure and collected using an x-ray diffractometer (type: shimadzu-6000, origin: japan) with a cu kα radiation (λ 1.154 a), with 2θ in the range 0° to 10° with scan rate 2(deg/min). the unit cell and d-spacing factors were obtained by using the equations nλ=2dsinθ and ao=2d100/√3. the sem analysis (scanning electron microscopy) show the morphology of mcm-41 was performed using sem instrument [type: vega 3 lm, origin: germany]. the ftir instrument was used to analyze the chemical bonds of mcm-41. the scanning range was 400– 4000 cm-1 and the resolution was 4 cm-1 and the analysis was carried out using ft-ir [type: bruker –tensor 27, origin: germany]. thermogravimetric analysis (tga) for mcm-41 and nys@mcm-41 was performed using thermogravimetric analyzer [type: sta pt1000, origin: usa], the sample was heated from room temperature to 600 oc with rate of heating 10 oc min−1 to obtain information concerning thermal stability. 2.4 nystatine loading the loading experiment was conducted by contacting 50 ml of known concentration of nys with a 0.14 g of mcm-41 in 50 ml of conical flasks which were closed and placed in a shaker at the constant agitation speed at room temperature. the amount of nys loaded was calculated using the absorbance values obtained at 305nm. the nys drug loading was estimated according to the eq.1 [21]. ���� ��� ��% = ����� �� ∗ 100% ... (1) 2.5 nystatine release the release of the nys from mcm-41 have done in laboratory equipment at given time intervals. the suspension was withdrawn by syringe into a quartz cuvette. the uv–vis spectrophotometer was used to measure the amount of the released drugs nys at 305 nm, according to equation (2)[22]. %release = ���� ! "# $%&� �' (")&!�"' ���� ! "# $%&� �' �*�( ∗ 100% … (2) 2.6 experimental design response surface methodology (rsm) is a statistical method used for experiment design and optimization where experimental responses are fitted with quadratic functions. the objective function of the current study was chosen to maximize the drug loading (dl%) though minimizing the dose of mesoporous carriers and concentration of drugs. historical data design was used to statistically optimize the formulations parameter and estimate the chief parameters effects, interactions effect and quadratic effect of the formulations ingredient on the % drug loading a nano carrier systems [23]. 3. results and discussion 3.1 x-ray diffraction pattern the different supports were characterized by standard technique. the x-ray patterns of the solid mcm-41 as produced. fig. (3) shows the presence of reflections at 2θ° angle of 2.86°, 4.4° and 5°, corresponding to planes (100), (110) and (200), reflections related through p6 mm hexagonal symmetry characteristic for mcm-41 material [24]. the position of the first peak, (1 0 0) that presented in fig. (3) allows direct determination of the center-center distance (the lattice parameters) between adjacent tubes using a0 = (2*d100/ √3 ) [25]. the calculated d100 and ao values are given in table (1). talib m. albayati al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 3443 (2019) 37 fig. 3. xrd pattern for mcm-41. 3.2 scanning electron microscopy (sem) the morphology of mesoporous materials was analyzed by sem. fig. (4) shows image of mcm41. the sem image obviously presented that mcm-41, indicate the presences of agglomerate sphere particles shapes and taking smooth surfaces. [26]. fig. 4. typical sem image for mcm-41. 3.3 ft.ir spectra fig. 5 shows ft-ir spectra of mcm-41. a broad band around 3442-3440 cm−1 is given to the stretching type vibration of surface silanol group (si–o–h) for mcm-41, which is associated with bending at a range 1687 and 1630 cm−1 and stretching type vibration of (h-o-h) hydrogen bonded water adsorbed on the surface for sba15. characteristic mesoporous silica si–o–si stretching mode vibration is observed at ,1336 cm−1 and ,1084 cm−1for mcm-41, which are assigned to symmetric and asymmetric stretching mode respectively. another peak at 467 cm−1 is the si–o–si bending type vibration [25]. fig. 5. ft-ir spectra of mcm-41. 3.4 thermal gravimetric analyses (tga) tga measures the losses in mass that is related to the total drug content in the sample. the tga curves for mcm-41, nys@mcm-41 are shown in fig.6. samples are heating to 600 ºc, at heating rate of 10 ºc/min. the thermal gravimetric curves presented weight loss of nys loading by mcm-41 (9.52%) and no weight loses of pure mcm-41. fig. 6. thermal gravimetric analysis for mcm-41 & nys@mcm-41. 3.5 response surface analysis for nys drug figs. 7 shows the effects of two factors in response (dl%), the effact of time and concentration in drug loading (dl%), when the ph =2 and dose. =0.14gm, observed that at intermediate concentration of nys drug at talib m. albayati al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 3443 (2019) 38 30mg/l, the drug loading efficiency of mesoporous increases when contact time at 24 h and at high concentration of nys drug stemmed in the formation of aggregate rather than mesoporous, which is extremely undesire so, the maximum dl% show in time=24h, conce. =30mg/l, ph =2 and dose. =0.14gm. table 1, the properties of mcm-41 structure. mesoporous d100 (nm) aο (nm) dp (nm) wt (nm) vp (cm3/g) sbet(m2/g) mcm-41 3.34 3.861 2.32 1.541 0.69 1394 • d-spacing of (100) reflection. unit cell constant, ao=2d100/√3. the thickness of the pore wall calculated by the difference (ao _ dp). at p/p0=0.982 of n2 volume adsorbed the total pore volume was taken. fig. 7. 3d surface plot & 2d contour plot for effect of time and conce. on dl%. 3.6 nystatine loading 3.6.1 effect of initial drug concentration the effect of initial nys concentration was studied by changing concentration from 10 mg/l to 100 mg/l as shown in fig.8 fig. 8. effect of the initial nys concentration on the dl% at: (ph=2, dosage=0.14g/50ml, contact time=24h). drug loading efficiency (dl%) decreased with increasing concentration of nys drug from 30mg/l to 80mg/l. the higher (dl%) were 90.47% at 30 mg/l, the lower (dl%) are 73.98% at concentration drug 80mg/l. the decrease of the drug loading of nys was due to, the mcm-41 had limited number of active sites which have become saturated above a certain concentration. conversely, in the case of a lower concentration of nys that more mesoporous sites were available for nys molecules, this is agreement with shah & rajput (2017) [27]. 3.6.2 effect of contact time the effect of contact time for loading nys drug by the mesoporous mcm-41 at c0 = 30 mg/l, ph =2 and dose = 0.14 g is shown in fig. 9. the rate of the drug loading is rapid in the first 30 min (48.64%) and, thereafter, the loading increased gradually and the it's reached equilibrium at 24hr (90.74%). large numbers of 0 20 40 60 80 100 0 10 20 30 40 50 60 70 80 90 d ru g lo a d in g % concentration(mg/l) talib m. albayati al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 3443 (2019) 39 devoid surface sites are obtainable for drug sorption through the initial stages, and after a period of time, the residual devoid surface sites are hard to be occupied because repulsive forces among the solute molecules on the solid and bulk phases [28], so we noted after 48hr the drug loading decrease to 89.11%. fig. 9. effect contact time on the drug loading at: (ph=2, dosage=0.14 g/50ml, conce. of drug=30 mg/l). 3.7 nystatine release the in vitro release of nys from mcm-41 mesoporous was carried out at ph 7.4 (the physiological ph in the human blood is around 7.4), and showed drug release behaviour fig. 10. at ph 7.4 and body temperature (37 °c), an uv vis spectrometer at 305 nm, was used to measure the nys release, after the initial release of nys is about 20% in first hour when the concentration gradient between surfaces of the mcm-41 in the bulk media (sbf, ph =7.4, t =37°c) was large, leading to large percent of nys released, the drug release rate was relatively slow and was further reduced after 18 h (equilibrium was reached). the cumulated release amount about 87.97% after 18 h and mechanism of the electrostatic repulsion, as experiential in mcm-41 mesoporous silica in which silanol group are deprotonate in ph 7.4 forcing the loading drug to be released and this phenomenon can be explained as follows the pbs is a negative charge inducer and have negatively zeta potential charge. so, it's possible to interaction with positively charged of nys drug. [29-30]. fig.10. release of nys from mcm-41 in sbf at: (ph =7.4, t =37°c). 3.8 kinetic release of nystatine the kinetic of drug release on mcm-41 was studied by using first order, higuchi, korsmeyerpeppas, and weibull kinetics models, by eq. (3, 4, 5 and 6). first order log 0100 − w3 = log100 − k1 t … (3) higuchi q = kh t1/2 ... (4) korsmeyer-peppas �! �6 = ktn … (5) weibull kinetics models log 7 ln 9 � ��#:; = mlog t −ln t0 … (6) it's used to estimate the mechanism of the drug release. the obtained results from the linearized of models for release of drugs (constants & correlation coefficient) are listed in table 2. table 2, release kinetic parameters of drugs in sbf (ph =7.4) drug first order higuchi korsmeyer-peppos weibull r2 k1 (h-1) r2 kh (%h1/2) r2 n k (h-n) r2 m nys@mcm-41 0.993 0.049 0.983 21.87 0.978 0.6089 17.9 0.995 0.796 0 20 40 60 80 100 0 12 24 36 48 time (h) d ru g lo a d in g % 0 10 20 30 40 50 60 70 80 90 100 0 6 12 18 24 30 36 42 48 c u m u la ti v e n y s r e le a se % time(h) talib m. albayati al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 3443 (2019) 40 fig. 11. kinetic release of nys for (a) first order, (b) higuchi model, (c) korsmeyers peppas, and (d) weibull models. 4. conclusions mesoporous silica mcm-41 with high surface area was synthesis by sol-gel technic and used as naocarrier in drug delivery system. nys was loading by mcm-41 and the maximum loading percentage was 90.74%. the nys release was studied at sbf media with ph (7.4). the time of nys release was (87.79%) after 18 hr. the kinetics of release of nys drug from mcm-41 is fully fit by a weibull model with a correlation coefficient of (0.995). abbreviations bet brunauer – emmett – teller ctab cetyltrimethyl ammonium bromide dp pore diameter iupac international pure and applied chemistry mcm mobil composition of matter msns mesoporous silica nanoparticles nys nystatine rsm response surface methodology sba santa barbara amorphous sbf simulated body fluid teos tetraethyl orthosilicate 5. references [1] varma, m. v., khandavilli, s., ashokraj, y., jain, a., dhanikula, a., sood, a., ... & agrawal, s. 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[21] ahmadi, e., dehghannejad, n., hashemikia, s., ghasemnejad, m., & tabebordbar, h. (2014). synthesis and surface modification of mesoporous silica nanoparticles and its application as carriers for sustained drug delivery. drug delivery, 21(3), 164-172. [22] lang, y., finn, d. p., pandit, a., & walsh, p. j. (2012). pharmacological activity of talib m. albayati al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 3443 (2019) 42 ibuprofen released from mesoporous silica. journal of materials science: materials in medicine, 23(1), 73-80. [23] chopra, s., patil, g. v., & motwani, s. k. (2007). release modulating hydrophilic matrix systems of losartan potassium: optimization of formulation using statistical experimental design. european journal of pharmaceutics and biopharmaceutics, 66(1), 73-82. [24] chen, x. y., shang, y. l., li, y. h., wang, j. x., maimouna, a. g., li, y. x., ... & pu, y. (2015). green preparation of uniform prednisolone nanoparticles using subcritical water. chemical engineering journal, 263, 20-26. [25] gunduz, o., yetmez, m., sonmez, m., georgescu, m., alexandrescu, l., ficai, a., ... & andronescu, e. (2015). mesoporous materials used in medicine and environmental applications. current topics in medicinal chemistry, 15(15), 1501-1515. [26] farjadian, f., ahmadpour, p., samani, s. m., & hosseini, m. (2015). controlled size synthesis and application of nanosphere mcm-41 as potent adsorber of drugs: a novel approach to new antidote agent for intoxication. microporous and mesoporous materials, 213, 30-39. [27] shah, p. v., & rajput, s. j. (2017). a comparative in vitro release study of raloxifene encapsulated ordered mcm-41 and mcm-48 nanoparticles: a dissolution kinetics study in simulated and biorelevant media. journal of drug delivery science and technology, 41, 31-44. [28] tsai, f. c., ma, n., chiang, t. c., tsai, l. c., shi, j. j., xia, y., ... & chuang, f. s. (2014). adsorptive removal of methyl orange from aqueous solution with crosslinking chitosan microspheres. journal of water process engineering, 1, 2-7. [29] lee, c. h., lo, l. w., mou, c. y., & yang, c. s. (2008). synthesis and characterization of positive‐charge functionalized mesoporous silica nanoparticles for oral drug delivery of an anti‐inflammatory drug. advanced functional materials, 18(20), 3283-3292. [30] falahat, r. (2016). tunable nano-delivery system for cancer treatment: a new approach for targeted localized drug delivery. )2019( 3443، صفحة 2د، العد15دجلة الخوارزمي الهندسية المجلم البياتيطالب محمد 43 لعالج النستاتين لنظام تسليم الدواء ةمادة ناقل mcm-41ة السليكا المساميَ علي محمد حمزه الخفاجي ** طالب محمد البياتي* الجامعة التكنولوجية /الهندسة الكيمياويةقسم ،*** talib_albyati@yahoo.com :البريد االلكتروني * alkafagae1986@yahoo.com :البريد االلكتروني ** الخالصة . أجريت sol-gelناقالت لألدوية سيئة للذوبان في الماء ، من خالل تقنية وصفهاب mcm-41في هذه الدراسة ، حضرت المادة النانوية المسامية ) ، ومسح المجهر ftir)، وجهاز فورير باألشعة تحت الحمراء (xrd( ةطة حيود أشعة السينيابوس mcm-41التوصيفات التركيبية والكيميائية لـ مع الحد األقصى لفعالية تحميل دواء النستاتين في mcm-41لنتائج التجريبية للناقل ). تم تحليل اtga) ، والتحليل الوزني الحراري (semاإللكتروني ( mcm-41 وتم دراسة اطالق عالج النستاتين المحمل بشكل حذر في سائل يحاكي جسم االنسان ٩٠٫٧٤ ان كفاءة التحميلوتبين .٪ (sbf) عند االس وجدت انها تخضع nysبيانات تحرر ساعة. ١٨٪) بعد ٨٧٫٧٩كان ( mcm-41لعالج من وأثبتت النتائج أن اطالق ا ٧٬٤الهيدروجيني ذو القيمة ). سّهل التصميم التجريبي للبيانات صياغة وتحسين الصيغة المثلى لتحميل الدواء ، وجمع المتغيرات٠٫٩٩٥معامل التصحيح ( وكان weibullلمعادلة al-khwarizmi engineering!!! journal al-khwarizmi engineering journal, vol. 6, no. 1, pp 80 87 (2010) modeling and simulation of sensorless speed control of a buck converter controlled dc motor bassim m. h. jassim * tagreed m. ali ** department of eelectrical engineering/ college of engineering/ university of baghdad * email: bassimmhj@yahoo.com ** email: tagmali@yahoo.com (received 24 march 2009: accepted 20 october 2009) abstract this paper investigate a sensorless speed control of a separately excited dc motor fed from a buck type dc-dc converter. the control system is designed in digital technique by using a two dimension look-up table. the performance of the drive system was evaluated by digital simulation using simulink toolbox of matlab. keywords: dc motor, speed control, buck converter. 1. introduction in speed control of the dc motor, high frequency output voltage ripple is achieved using dc chopper where the average voltage across the motor terminals can be controlled by using the duty ratio of power switching device [sen]. different control methods have been used to regulate the motor speed like pi controller [gurbuz] and fuzzy logic control [tipsuwanporn]. in much application the use of speed sensors like tachogenerator or shaft encoder will add a significant cost and weight to the drive system. in this work, high chopping frequency is achieved using a mosfet as a switching device and a smooth dc output voltage and current are generated using a buck type dc-dc converter with sensorless speed control technique to reduce the cost and weight of the drive system. the control method is simple and reliable and does not need exact system parameters measurement when implemented practically. the buck converter circuit design is presented in section ii, while section iii explains the proposed control technique with a two dimension look-up table which is used in speed control of induction machines [jeftenic]. the complete system is modeled in section iv, and then simulated using simulink toolbox of matlab in section v. finally section vi presents the simulation results and conclusion for the proposed control system for both step change in reference speed and motor load. 2. buck converter design the buck converter circuit diagram is shown in fig.1, where the steady state output voltage depends linearly on the duty ratio d where: va =d.vs 0  d  1 …(1) the buck converter modes of operation are explained in details by [mohan]. the converter switching frequency is 20 khz, and the input voltage is 240v. fig.1. buck converter circuit diagram. bassim m. h. jassim!!!! al-khwarizmi engineering journal, vol.6, no.1, pp 80 -87 (2010) 81 2.1. inductor design the inductor value depends on the admissible current ripple il which is given by the following relation [mohan]: l il 1  (vs – va ). fs d …(2) the continuous conduction mode of the converter is ensured by making the minimum output current equal to the motor no load current which is about 2a for the used motor in this work. therefore ail 4 is the maximum admissible value. solving eq. (2) for l yields: il tsdvavs l    .).( …(3) where: fs ts 1  substituting eq.(1) by eq.(3) gives: il tsddvs l    .)1( …(4) clearly the maximum value of the right hand side of eq. (4) occurs at 5.0d ; thus the value of the inductor becomes: il tsvs l   4 . …(5) taking ail 2 to ensure more smoothness, the value of the inductor will be 1.5 mh . 2.2. capacitor design the output voltage ripple can be minimized by making the corner frequency fc of the output lc filter as fsfc  ; also a rule of thumb of /300 f a minimum at khz20 is more realistic when electrolytic capacitors are used[chyrysis] and a ccordingly for the a20 rated armature current, the capacitor selected to be two of f4700 connected in parallel is to reduce the equivalent series resistance of the capacitor. 3. the proposed control concept the well known equation of the dc motor is: raiaegva . …(6) where: nkaeg . …(7) using the last two equations with eq.(1), yields: vs raianka d ..   …(8) then: ),( ianfd  …(9) the proposed algorithm assumes that the reference speed is equal to the actual speed, so if there is a two dimension look-up table in which the first field represents motor speed, the second field represents the armature current and the third one represents the duty ratio; then the required duty ratio can be calculated for a given reference speed and motor load which is estimated by the armature current. the schematic of the drive and control system is shown in fig.2. for operating points not included in the table, cubic spline interpolation and extrapolation is used to calculate the required duty ratio. the two dimension look-up table can be formed in two ways. the first method uses simple measurements for small number of operating points while in the second method, the steady state dc motor equivalent circuit is used to calculate the required armature voltage and then the duty ratio for a given reference speed and motor load. fig.2. buck converter controlled dc motor fig.3 shows the calculated function ),( ianreffd  , from which the required duty ratio is calculated for a given reference speed and armature current, therefore, the speed can be controlled using only the armature current signal. a current limiter is used to protect the system from the large starting and transient currents, which can damage the converter and possibly the motor. bassim m. h. jassim!!!! al-khwarizmi engineering journal, vol.6, no.1, pp 80 -87 (2010) 82 4. system modeling and simulation this section includes the modeling of the dc motor and the buck converter, and then the overall system is simulated using simulink toolbox of matlab. 4.1. dc motor modeling a separately excited dc motor is modeled by the equations below [tipsuwanporn]: t ia laiaraegva    .. …(10) where: nkaeg .. the torque balance equation is: t n jnbtlt    .. …(11) where: iakat . 4.2. buck converter modeling the buck converter is modeled using the equations [chrin]: )..( 1 vorlilvsd lt il    …(12) )( 1 ioil ct vc    …(13) )(re ioilsrvcvo  …(14) where: 1d when the switch is on. 0d when the switch is off. using the equations (10-14) with the look-up table, fig.4 shows the overall system simulation while fig.5 and fig.6 are the simulation of the dc motor and the buck converter respectively using simulink toolbox of matlab. 1000 1200 1400 1600 1800 2000 0 10 20 30 0.2 0.3 0.4 0.5 0.6 0.7 motor speed,[rpm] fig.3 the duty ratio vs. the armature current and motor speed armature current,[amp.] d ut y r at io fig.3. the duty ratio vs. the armature current and motor speed bassim m. h. jassim!!!! al-khwarizmi engineering journal, vol.6, no.1, pp 80 -87 (2010) 83 5. simulation results and conclusion based on the system model, the motor parmeters, and the converter parameters shown in the appendix, simulink is used to simulate the system under consideration. simulation results are shown in fig.7 and fig.8 for step response for speed change from 1000 rpm to 1800 rpm ( 104.7 rad/sec to 188.5 rad/sec) and from 1800 rpm to 1000 rpm at rated motor load, and for step change in motor load from 7 n.m to 11 nm and from 11 nm to 7nm at rated speed respectively. these figures clarify the soft start of the motor and the operation of the current limit as well as the satisfactory transient response. the results demonstrate the effectiveness of the proposed control scheme. one can conclude that the steady state accuracy depends mainly on the look-up table forming. the experimental method for producing a look-up table will lead to more accurate results than that of the method of calculation used in this work since it takes into account some effects, like the parasitic elements not considered in the model. practical implementation of this proposed control method doesn’t require exact motor parameters measurement and lookup table can be changed easily without any hardware modification to take into account the mechanical status of the motor which is changed after a long period of operation. referance speed armature current current limitter 25 subsystem3 dc motor in1 in2 out1 out2 subsystem1 buck converter in1 in2 in3 out1 step2 step1 scope 3 scope 1 saturation repeating sequence 20khz relay 1 relay low pass filter 1 0.005 s+1 lookup table (n-d) 2-d t (u)u1 u2 logical operator and input voltage 240 motor load torque armature voltage speed in rad/sec armatue current duty ratio fig. 4. simulink of a sensorless buck converter controlled dc motor. bassim m. h. jassim!!!! al-khwarizmi engineering journal, vol.6, no.1, pp 80 -87 (2010) 84 ra ia kaphi b n (rad /sec)1/j kaphi 1/la armature current armature voltage out22 out 1 1 integrator 2 1 s integrator 1 s -kgain 9 -k-kgain 6 1 gain 4 -k-kin 2 2 in1 1 fig. 5. simulink of a separately excited dc motor. rl vo= armature voltage il input voltage duty ratio armatue current out 1 1 resr -kproduct integrator 3 1 s integrator 1 1 s -k1/l -k1/c -kin3 3 in2 2 in1 1 fig. 6. simulink of buck converter. bassim m. h. jassim!!!! al-khwarizmi engineering journal, vol.6, no.1, pp 80 -87 (2010) 85 0 5 10 15 20 25 30 -50 0 50 100 150 200 time in sec fig.8. transient response due to step change in load. speed in rad/sec current in amp. speed & armature current 0 5 10 15 20 25 30 -50 0 50 100 150 200 time in sec. fig.7. transient response due to step change in speed. current in ampere speed in rad/sec speed & arrmature current bassim m. h. jassim!!!! al-khwarizmi engineering journal, vol.6, no.1, pp 80 -87 (2010) 86 notation eg motor generated voltage (or back emf). fs converter switching frequency. ia motor armature current. il converter inductor current. io converter output current. n motor speed. nref motor reference speed. t developed torque. va motor armature voltage. vc converter capacitor voltage. vo converter output voltage. a ampere b friction coefficient. c converter capacitance. d duty ratio eg average motor generated voltage. ia average armature current. j moment of inertia. ka back emf and torque constant. l converter inductance. la motor armature circuit inductance. ra motor armature circuit resistance. srre capacitor equivalent series resistance. rl converter inductor internal resistance. tl load torque. va average motor armature voltage. vc average capacitor voltage. vo average converter output voltage. vs converter input voltage. il inductor current ripple. appendix the dc motor used has the following specifications: dc motor, 110v, 2.5 hp, 1800rpm, aia 20  1ra , ,46mhla  mkgj  093.0 2 for the motor and its connected load, .sec/..008.0 radmnb  for the motor and its coupled load., radvka sec/.55.0 , which is the back emf and torque constant. the buck converter specifications are: input voltage vvs 240 . output voltage vavo  is adjustable according to required speed and load. output current iaio  . mhl 5.1 , with internal resistance rl 0.017 , c two capacitors connected in parallel each of 4700 .f with srre 0.25 , switching frequency .20khzfs  6. references [1] chrip, p. and bunlaksananusorn, c,”large signl average modeling and simulation of dcdc converters with simulunk,” ieeepower conversion conference-nagoya, 2007. [2] chyrysis, c. george, high frequency switching power supplies, 2nd ed., mcgrawhill, 1989. [3] gurbuz fatma and eyup akpinar,”stablity analysis of a closed loop control for a pulse width modulated dc motor drive,” turk j elect. engin., vol.10, no.3, 2002. [4] jeftenic, b.i., bebic, m.z., and nitrovic, n.n.,” a simplified speed sensorless control for variable frequency induction motor drives,” ieee transaction on energy conversion, vol.14, no.3, sept. 1999. [5] mohan, n., undland, t.m., and robbin, w.p., power electronics: converters application and design, 3rd ed., wiley& sons, 2003. [6] sen, p.c., principles of electric machines and power electronics, 2nd ed., john wiley & sons, 1997. [7] tipsuwanporn, v., numsomran, a., and klinsmitth, n.,” separately excited dc motor with fuzzy self organizing,” international conference on control, automation and systems. oct.,2007. )2010( 87-80 ، صفحة1، العدد 6مجلة الخوارزمي الھندسیة المجلد باسم محمد جاسم 87 نمذجة ومحاكاة محرك تیار مستمر مسیطر علیھ بواسطة مغیر تیار مستمر خافض للفولتیھ وبدون متحسس سرعھ **تغرید محمد علي *باسم محمد حسن جاسم جامعة بغداد/ كلیة الھندسھ/ قسم الھندسھ الكھربائیھ bassimmhj@yahoo.com:البرید االلكتروني * tagmali@yahoo.com:البرید االلكتروني ** الخالصة buck)(رك تیار مستمر منفصل االثاره بواسطة محول تیار مستمر خافض للفولتیھ من نوع تحقق ھذه الورقھ البحثیھ في امكانیة السیطره على سرعة مح ثم تم تقییم مواصفات النظام من خالل محاكاة النظام باستخدام وبدون استخدام متحسس سرعھ وباستخدام تقنیھ رقمیھ من خالل استخدام جدوال ثنائي االبعاد simulink toolbox).(مایسمى بالـ 1000 1200 1400 1600 1800 2000 0 10 20 30 0.2 0.3 0.4 0.5 0.6 0.7 motor speed,[rpm] fig.3 the duty ratio vs. the armature current and motor speed armature current,[amp.] duty ratio £ £ gate drive duty ratio input voltage vs l c mosfet il d l il 1 º d fs d a il 4 = d l il ts d va vs l d = . ). ( fs ts 1 = il ts d d vs l d = . ) 1 ( 5 . 0 = d il ts vs l d = 4 . a il 2 = d mh fc fs fc << / 300 f m a khz 20 a 20 f m 4700 ra ia eg va . + = n ka eg . f = vs ra ia n ka d . . + f = ) , ( ia n f d = m gate drive lookup table lpf reference speed armature current duty ratio input voltage vs armature voltage va l c mosfet ) , ( ia nref f d = t ia la ia ra eg va ¶ ¶ + + = . . n ka eg .. f = t n j n b tl t ¶ ¶ + + = . . ia ka t . f = ) . . ( 1 vo rl il vs d l t il = ¶ ¶ ) ( 1 io il c t vc = ¶ ¶ ) ( re io il sr vc vo + = 1 = d 0 = d referance speed armature current current limitter 25 subsystem3 dc motor in1 in2 out1 out2 subsystem1 buck converter in1 in2 in3 out1 step2 step1 scope3 scope1 saturation repeating sequence 20khz relay1 relay low pass filter 1 0.005s+1 lookup table (n-d) 2-d t(u) u1 u2 logical operator and input voltage 240 motor load torque armature voltage speed in rad/sec armatue current duty ratio ra ia kaphi b n (rad/sec) 1/j kaphi 1/la armature current armature voltage out22 out1 1 integrator2 1 s integrator 1 s -kgain9 -k-kgain6 1 gain4 -k-kin2 2 in1 1 rl vo= armature voltage il input voltage duty ratio armatue current out1 1 resr -kproduct integrator3 1 s integrator1 1 s -k1/l -k1/c -kin3 3 in2 2 in1 1 eg fs ia il io n nref t va vc vo b c d eg ia j f ka l la ra sr re rl tl va vc vo vs il d a ia 20 = w = 1 ra , 46 mh la = m kg j = 093 . 0 . sec/ . . 008 . 0 rad m n b = rad v ka sec/ . 55 . 0 = f v vs 240 = va vo = ia io = mh l 5 . 1 = = rl w = c 4700 . f m = sr re w . 20 khz fs =  title  gate drive look-up table lpf reference speed armature current duty ratio input voltage vs armature voltage va l c mosfet title  gate drive duty ratio input voltage vs l c mosfet modeling and simulation of sensorless speed control of a buck converter controlled dc motor bassim m. h. jassim al-khwarizmi engineering journal, vol.6, no.1, pp 80 -87 (2010) al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 6, no. 1, pp 80 87 (2010) modeling and simulation of sensorless speed control of a buck converter controlled dc motor bassim m. h. jassim * tagreed m. ali ** department of eelectrical engineering/ college of engineering/ university of baghdad * email: bassimmhj@yahoo.com ** email: tagmali@yahoo.com (received 24 march 2009: accepted 20 october 2009) abstract this paper investigate a sensorless speed control of a separately excited dc motor fed from a buck type dc-dc converter. the control system is designed in digital technique by using a two dimension look-up table. the performance of the drive system was evaluated by digital simulation using simulink toolbox of matlab. keywords: dc motor, speed control, buck converter. 1. introduction in speed control of the dc motor, high frequency output voltage ripple is achieved using dc chopper where the average voltage across the motor terminals can be controlled by using the duty ratio of power switching device [sen]. different control methods have been used to regulate the motor speed like pi controller [gurbuz] and fuzzy logic control [tipsuwanporn]. in much application the use of speed sensors like tachogenerator or shaft encoder will add a significant cost and weight to the drive system. in this work, high chopping frequency is achieved using a mosfet as a switching device and a smooth dc output voltage and current are generated using a buck type dc-dc converter with sensorless speed control technique to reduce the cost and weight of the drive system. the control method is simple and reliable and does not need exact system parameters measurement when implemented practically. the buck converter circuit design is presented in section ii, while section iii explains the proposed control technique with a two dimension look-up table which is used in speed control of induction machines [jeftenic]. the complete system is modeled in section iv, and then simulated using simulink toolbox of matlab in section v. finally section vi presents the simulation results and conclusion for the proposed control system for both step change in reference speed and motor load. 2. buck converter design the buck converter circuit diagram is shown in fig.1, where the steady state output voltage depends linearly on the duty ratio d where: va =d.vs 0 d 1 …(1) the buck converter modes of operation are explained in details by [mohan]. the converter switching frequency is 20 khz, and the input voltage is 240v. fig.1. buck converter circuit diagram. 2.1. inductor design the inductor value depends on the admissible current ripple which is given by the following relation [mohan]: (vs – va ). …(2) the continuous conduction mode of the converter is ensured by making the minimum output current equal to the motor no load current which is about 2a for the used motor in this work. therefore is the maximum admissible value. solving eq. (2) for yields: …(3) where: substituting eq.(1) by eq.(3) gives: …(4) clearly the maximum value of the right hand side of eq. (4) occurs at ; thus the value of the inductor becomes: …(5) taking to ensure more smoothness, the value of the inductor will be 1.5 . 2.2. capacitor design the output voltage ripple can be minimized by making the corner frequency of the output lc filter as ; also a rule of thumb of embed equation.3 minimum at is more realistic when electrolytic capacitors are used[chyrysis] and a ccordingly for the rated armature current, the capacitor selected to be two of connected in parallel is to reduce the equivalent series resistance of the capacitor. 3. the proposed control concept the well known equation of the dc motor is: …(6) where: …(7) using the last two equations with eq.(1), yields: …(8) then: …(9) the proposed algorithm assumes that the reference speed is equal to the actual speed, so if there is a two dimension look-up table in which the first field represents motor speed, the second field represents the armature current and the third one represents the duty ratio; then the required duty ratio can be calculated for a given reference speed and motor load which is estimated by the armature current. the schematic of the drive and control system is shown in fig.2. for operating points not included in the table, cubic spline interpolation and extrapolation is used to calculate the required duty ratio. the two dimension look-up table can be formed in two ways. the first method uses simple measurements for small number of operating points while in the second method, the steady state dc motor equivalent circuit is used to calculate the required armature voltage and then the duty ratio for a given reference speed and motor load. fig.2. buck converter controlled dc motor fig.3 shows the calculated function , from which the required duty ratio is calculated for a given reference speed and armature current, therefore, the speed can be controlled using only the armature current signal. a current limiter is used to protect the system from the large starting and transient currents, which can damage the converter and possibly the motor. 4. system modeling and simulation this section includes the modeling of the dc motor and the buck converter, and then the overall system is simulated using simulink toolbox of matlab. 4.1. dc motor modeling a separately excited dc motor is modeled by the equations below [tipsuwanporn]: …(10) where: the torque balance equation is: …(11) where: 4.2. buck converter modeling the buck converter is modeled using the equations [chrin]: …(12) …(13) …(14) where: when the switch is on. when the switch is off. using the equations (10-14) with the look-up table, fig.4 shows the overall system simulation while fig.5 and fig.6 are the simulation of the dc motor and the buck converter respectively using simulink toolbox of matlab. 5. simulation results and conclusion based on the system model, the motor parmeters, and the converter parameters shown in the appendix, simulink is used to simulate the system under consideration. simulation results are shown in fig.7 and fig.8 for step response for speed change from 1000 rpm to 1800 rpm ( 104.7 rad/sec to 188.5 rad/sec) and from 1800 rpm to 1000 rpm at rated motor load, and for step change in motor load from 7 n.m to 11 nm and from 11 nm to 7nm at rated speed respectively. these figures clarify the soft start of the motor and the operation of the current limit as well as the satisfactory transient response. the results demonstrate the effectiveness of the proposed control scheme. one can conclude that the steady state accuracy depends mainly on the look-up table forming. the experimental method for producing a look-up table will lead to more accurate results than that of the method of calculation used in this work since it takes into account some effects, like the parasitic elements not considered in the model. practical implementation of this proposed control method doesn’t require exact motor parameters measurement and lookup table can be changed easily without any hardware modification to take into account the mechanical status of the motor which is changed after a long period of operation. fig. 4. simulink of a sensorless buck converter controlled dc motor. fig. 5. simulink of a separately excited dc motor. fig. 6. simulink of buck converter. notation motor generated voltage (or back emf). converter switching frequency. motor armature current. converter inductor current. converter output current. motor speed. motor reference speed. developed torque. motor armature voltage. converter capacitor voltage. converter output voltage. a ampere friction coefficient. converter capacitance. duty ratio average motor generated voltage. average armature current. moment of inertia. back emf and torque constant. converter inductance. motor armature circuit inductance. motor armature circuit resistance. capacitor equivalent series resistance. converter inductor internal resistance. load torque. average motor armature voltage. average capacitor voltage. average converter output voltage. converter input voltage. inductor current ripple. appendix the dc motor used has the following specifications: dc motor, 110v, 2.5 hp, 1800rpm, , 2 for the motor and its connected load, for the motor and its coupled load., , which is the back emf and torque constant. the buck converter specifications are: input voltage . output voltage is adjustable according to required speed and load. output current . , with internal resistance 0.017 , two capacitors connected in parallel each of embed equation.3 with 0.25 , switching frequency 6. references [1] chrip, p. and bunlaksananusorn, c,”large signl average modeling and simulation of dc-dc converters with simulunk,” ieeepower conversion conference-nagoya, 2007. [2] chyrysis, c. george, high frequency switching power supplies, 2nd ed., mcgraw-hill, 1989. [3] gurbuz fatma and eyup akpinar,”stablity analysis of a closed loop control for a pulse width modulated dc motor drive,” turk j elect. engin., vol.10, no.3, 2002. [4] jeftenic, b.i., bebic, m.z., and nitrovic, n.n.,” a simplified speed sensorless control for variable frequency induction motor drives,” ieee transaction on energy conversion, vol.14, no.3, sept. 1999. [5] mohan, n., undland, t.m., and robbin, w.p., power electronics: converters application and design, 3rd ed., wiley& sons, 2003. [6] sen, p.c., principles of electric machines and power electronics, 2nd ed., john wiley & sons, 1997. [7] tipsuwanporn, v., numsomran, a., and klinsmitth, n.,” separately excited dc motor with fuzzy self organizing,” international conference on control, automation and systems. oct.,2007. نمذجة ومحاكاة محرك تيار مستمر مسيطر عليه بواسطة مغير تيار مستمر خافض للفولتيه وبدون متحسس سرعه باسم محمد حسن جاسم* تغريد محمد علي** قسم الهندسه الكهربائيه/ كلية الهندسه/ جامعة بغداد * البريد الالكتروني:bassimmhj@yahoo.com ** البريد الالكتروني:tagmali@yahoo.com الخلاصة تحقق هذه الورقه البحثيه في امكانية السيطره على سرعة محرك تيار مستمر منفصل الاثاره بواسطة محول تيار مستمر خافض للفولتيه من نوع ((buck وبدون استخدام متحسس سرعه وباستخدام تقنيه رقميه من خلال استخدام جدولا ثنائي الابعاد ثم تم تقييم مواصفات النظام من خلال محاكاة النظام باستخدام مايسمى بالـ ( .(simulink toolbox speed & armature current fig.3. the duty ratio vs. the armature current and motor speed � embed pbrush ��� current in amp. speed in rad/sec fig.8. transient response due to step change in load. time in sec 200 150 100 50 0 -50 30 25 20 15 10 5 0 speed & arrmature current speed in rad/sec current in ampere fig.7. transient response due to step change in speed. time in sec. 200 150 100 50 0 -50 30 25 20 15 10 5 0 page 87 _1296934685.unknown _1299263091.unknown _1325135462.unknown _1325135529.unknown _1325135558.unknown _1325135619.unknown _1325135632.unknown _1325135643.unknown _1325135671.unknown _1325135677.unknown _1325135665.unknown _1325135638.unknown _1325135626.unknown _1325135571.unknown _1325135612.unknown _1325135565.unknown _1325135541.unknown _1325135548.unknown _1325135535.unknown _1325135492.unknown _1325135513.unknown _1325135523.unknown _1325135499.unknown _1325135478.unknown _1325135485.unknown _1325135471.unknown _1325135428.unknown _1325135444.unknown _1325135453.unknown _1325135436.unknown _1318274468.vsd _1325135416.unknown _1318269363.vsd _1297011020.unknown _1297012240.unknown _1297312589.unknown _1297313078.unknown _1297488201.unknown _1297489150.unknown _1297489377.unknown _1297489422.unknown _1297489099.unknown _1297313259.unknown _1297313286.unknown _1297313359.unknown _1297313178.unknown _1297312908.unknown _1297313053.unknown _1297312822.unknown _1297312400.unknown _1297312516.unknown _1297312141.unknown _1297312208.unknown _1297312078.unknown _1297011609.unknown _1297011955.unknown _1297012111.unknown _1297011796.unknown _1297011290.unknown _1297011458.unknown _1297011207.unknown _1296974739.unknown _1296975051.unknown _1296976089.unknown _1296974910.unknown _1296934917.unknown _1296974658.unknown _1296934828.unknown _1296933640.unknown _1296934230.unknown _1296934621.unknown _1296934656.unknown _1296934402.unknown _1296933919.unknown _1296934117.unknown _1296933749.unknown _1296933105.unknown _1296933469.unknown _1296933506.unknown _1296933344.unknown _1296932274.unknown _1296932779.unknown _1296933029.unknown _1296932197.unknown _1173207870 alkhwarizmi engineering journal al-khwarizmi engineering journal, vol. 6, no. 3, pp 77 84 (2010) corrosion behavior of ti-6al-4v alloy in different media majid h. abdulmageed* slafa i. ibrahim ** * department of materials engineering/ university of technology email: majed_hamed60@yahoo.com ** energy and fuel research center/ university of technology (received 25 october 2009; accepted 27 july 2010) abstract in this work the corrosion behavior of ti-6al-4v alloy was studied by using galvanostatic measurements at room temperature in different media which includ sodium chloride (food salt), sodium tartrate (presence in jellies, margarine, and sausage casings,etc.), sodium oxalate (presence in fruits, vegetables,etc.), acetic acid (presence in vinegar), phosphoric acid (presence in drink), sodium carbonate (presence in 7up drink,etc.), and sodium hydroxide in order to compare. corrosion parameters were interpreted in these media which involve corrosion potential( ecorr) and corrosion current density (icorr), since the results of (ecorr) indicate that oxalate ions are more corrosive than other materials while the results of (icorr) indicate that nacl is more corrosive than other materials. cathodic and anodic tafel slopes that were used to calculate the polarization resistance (rp) to know which materials effect on ti-6al-4v alloy uses in dental materials and the results of (rp) were: na2co3 >oxalate >h3po4 >ch3cooh >naoh >tartrate >nacl. the change in free energy (∆g) and rate of corrosion in (mpy) were calculated, and the results of rate indicate that increasing in the following sequences: nacl>tartrate >naoh >oxalate> ch3cooh> h3po4> na2co3. keywords: corrosion, titanium alloy, free energy, tafel method. 1. introduction titanium and its alloy provide excellent resistance to general and localized attack under most oxidizing, neutral and inhibited reducing conditions in aqueous environments and remain passive under mildly reducing conditions, although they may be attacked by strongly reducing or complexing media . titanium is especially known for its outstanding resistance to chlorides and other halides generally present in most process streams. [1] a study of the corrosion resistance of titanium is basically a study of the properties of the oxide film. the oxide film on titanium is very stable and is attacked only by a few substances including hot concentration reducing acids, most notably, hydrofluoric acid. titanium is capable of healing this film almost instantaneously in every environment where a trace of moisture or oxygen is present because of titanium’s strong affinity for oxygen. anhydrous conditions in the absence of a source of oxygen should be avoided since the protective film may not be regenerated if damaged. figure (1) shows the pourbaix diagram of ti/h2o system. there are many studies about corrosion of tialloy from many authors, smith bj and coworkers studies of fretting corrosion experiments were performed on ti-6al-4v similar metal, pinon-flat fretting couple, relative displacement amplitudes between the fretting specimens were directly measured using lvdt`s. [2] latifa kinani, abdelilah chtani and coworkers studies the effect of eugenol on the titanium corrosion in artificial saliva enriched with eugenol at different concentration. the corrosion behavior and titanium surface characterization were investigated by electrochemical measurements. [3] this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ majid h. abdulmageed al-khwarizmi engineering journal, vol. 6, no. 3, pp 77 84 (2010) 78 m.nakagaw and co-workers studies titanium which is used as a metal for biocompatible materials such as dental implants or restorations because of its excellent chemical stability [4]. chohayeb a.a. and co-workers studies the corrosion behavior of couples consisting of titanium and one of the dental casting alloys, nicr, co-cr, au-pd-ag or pd-ag. alloys and ti were studied using materials in the cast condition. potentiodynamic polarization techniques were used for making electrochemical measurements on the alloys and couples in artificial saliva at 37oc. corrosion potentials, corrosion rates and general corrosion behavior, including passivation range and breakdown potentials, were determined for all materials and couples. [5] in this study we choose some media which have an effect on the titanium alloy in the field of dentistry such as nacl, oxalate, tartrate, carbonate, acetic acid, phosphoric acid and naoh. 2. experimental part 2.1. materials and chemicals ti-6al-4v alloy was cut into square shape with (1cm2) area and (1cm) thickness, and made into electrode by pressing a copper wire into a hole on one side and then insulating all but one side with an epoxy resin (fig. 1). fig.1. pourbaix diagram of ti/h2o system. the exposed area was grinding on emery papers 400,600 and 1000-mesh grit. a braiding was done by power-driven wheels. the electrochemical cell was of the usual type (fig. 2) with provision for working electrode (ti-alloy), auxiliary electrode (pt electrode), and a luggin capillary for connection with an sce reference electrode. fig.2. (a)-the standard corrosion cell (astm) [7]. (b)working electrode. many materials were used in this work such as materials that have effects on ti-alloy in dentistry field and some of them have general effect. these materials are shown in table (1). table 1, the molecular weight and purity of materials. materials m. wt (g.mol-1) concentration sodium hydroxide 40.00 0.1m sodium chloride 58.44 0.1m potassium hydrogen tartrate 188.18 0.1m acetic acid 60.0 10%m phosphoric acid 68 4%m sodium carbonate 106 0.1m sodium oxalate 134 0.1m hole to electrical connection alloy epoxy resin (a) (b) this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ majid h. abdulmageed al-khwarizmi engineering journal, vol. 6, no. 3, pp 77 84 (2010) 79 2.2. galvanostatic measurement the galvanostatic was measured using wenking m lab. from bank elektronik (germany). the galvanostatic scan started about ¼ hour after the electrode immersion in the test solution, the range of voltage depending on ocp value versus the saturated calomel electrode. both the cathodic and anodic curves were obtained with decreasing and increasing polarization, and this was repeated several times. the polarization curve obtained involved the cathodic and anodic regions. extensive data could be derived from the detailed analysis of each polarization region using extrapolated method to determine both the corrosion current density (icorr) and corrosion potential (ecorr) . 3. results and discussion 3.1. corrosion behavior the study of polarization behavior of ti-6al4v alloy in different media involves the active region which consists of cathodic and anodic region to calculate the corrosion potentials and corrosion current densities by using linear tafel method. figs. (3) to (9) show the polarization curves of ti-6al-4v in different media. the corrosion parameters of ti-6al-4v in different media were listed in table (2). the cathodic region represents the reduction reaction which occurs on the surface of alloy according to the medium of corrosion. 2h+ +2e → h2 (in the acidic medium) …(1) ½ o2 + h2o +2e → 2oh (in the neutral and basic solution ) …(2) while the anodic region represent the dissolution of metal or metals in alloy to ions according to the following reactions: ti → ti2+ + 2e …(3) fig.3. polarization curve of ti-6al-4v alloy in nacl solution at room temperature. fig.4. polarization curve of ti-6al-4v alloy in sodium tartrate solution at room temperature. fig.5. polarization curve of ti-6al-4v alloy in sodium hydroxide solution at room temperature. p ot en tia l ( m v ) po te nt ia l ( m v ) po po po te nt ia l ( m v ) this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ majid h. abdulmageed al-khwarizmi engineering journal, vol. 6, no. 3, pp 77 84 (2010) 80 fig.6. polarization curve of ti-6al-4v alloy in sodium oxalate solution at room temperature. fig.7. polarization curve of ti-6al-4v alloy in ch3cooh solution at room temperature. fig.8. polarization curve of ti-6al-4v alloy in h3po4 solution at room temperature. fig.9. polarization curve of ti-6al-4v alloy in na2co3 solution at room temperature. table 2, the corrosion parameters of ti-6al-4v in different media. medium corrosion potential -ecorr(mv) (sce) corrosion current density icorr (µa.cm-2) *10-3 -bc (mv.dec-1) +ba (mv.dec-1) rpx10-7 (ω.cm-2) nacl 148.26 1357.6 113.0 206.6 0.2330 sodium tartarate 1317.3 160.68 199.3 666.5 4.1460 naoh 1029.2 114.83 221.7 741.3 6.4530 sodium oxalate 1324.2 75.48 261.7 678.9 10.866 acetic acid 736.8 63.95 171.5 333.5 7.6900 phosphoric acid 639.9 63.91 216.3 452.5 9.9420 na2co3 1319.9 61.43 225.9 862.0 12.652 po te nt ia l p ot en tia l ( m v ) po te nt ia l po te nt ia l ( m v ) po te nt ia l po te nt ia l ( m v ) po te nt ia l po te nt ia l ( m v ) this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ majid h. abdulmageed al-khwarizmi engineering journal, vol. 6, no. 3, pp 77 84 (2010) 81 3.2. corrosion parameters the corrosion potential (ecorr) of material in a certain medium at a constant temperature is a thermodynamic parameter which is a criterion for the extent of the corrosion feasibility under the equilibrium potential (in opposite sign) of the cell consisting of the working electrode and the auxiliary electrode when the rate of anodic dissolution of working electrode material becomes equal to the rate of the cathodic process that take place on the same electrode surface. from the results of (ecorr) in table (2), it can be shown that: -ecorr (mv) oxalate>na2co3>tartrate>naoh> ch3cooh>h3po4>nacl it is shown that (ecorr) value is a measure for the extent of the feasibility of the corrosion reaction on purely thermodynamic basis. the corrosion current density (icorr) is a kinetic parameter and represents the rate of corrosion under specified equilibrium condition. at constant temperature for ti-6al-4v alloy, (icorr) values vary with variation of ions present in medium and take the following sequences: icorr (μa/cm2) nacl> tartrate >naoh>oxalate> ch3cooh> h3po4>na2co3 from deep analysis of the cathodic and anodic regions of the polarization curves for ti-6al-4v alloy in different media, it was possible to derive data concerning the cathodic and anodic tafel slopes. from the results which shown in table (2), values of tafel slopes (bc & ba) for both cathodic and anodic reactions were generally close to or higher than 120 mv/decade. a cathodic tafel slope of -120 mv/decade in general diagnostic of a discharge – chemical desorption mechanism for hydrogen evolution reaction of the cathode in which the proton discharge is the rate – determining step. where the two basic reactions paths for hydrogen evolution reaction are: h3o + (bulk solution) h3o + (metal/solution interface) …(4) this is followed by the discharge step: h3o + + m + e → m–h + h2o …(5) another parameter can be calculated from corrosion measurement is the polarization resistance (rp) which represent the measure of the resistance of the metal to corrosion in the solution in which the metal is immersed. the polarization resistance (rp) can be determined from sterngeary equation [6]: corrca ca i p ibb bb di de r )(303.20         ...(6) where e is the applied potential (volt) , i is the current density (a.cm-2) and bc, ba are cathodic and anodic tafel slops respectively. the values of rp are presented in table (2) which indicates that the corrosion in the sodium carbonate (na2co3) solution resists more than the other solutions. the values of polarization resistance in the other solution take the following sequence: rp (ω.cm-2) na2co3 >oxalate >h3po4> ch3cooh >naoh >tartrate >nacl 3.3. the free-energy change (∆g) the free-energy change accompanying an electrochemical reaction can be calculated by the following equation [7]: ∆g = -nfe …(7) where ∆g is the free-energy change, n is the number of electrons involved in the reaction, f is the faraday constant, and e equals the cell potential. under standard conditions, the standard free energy of the cell reaction ∆g is directly related to the standard potential difference across the cell, e0 ∆g0= -nfe0 …(8) electrode potential can be combined algebraically to give cell potential. for a galvanic cell, which operates spontaneously, a positive cell voltage will be obtained if the difference is taken in the usual way, as ecell = ecathode – eanode ….(9) the free energy change in a galvanic cell, or in a spontaneous cell reaction, is negative and the cell voltage is positive. in electrolytic cell, the diffusion this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ majid h. abdulmageed al-khwarizmi engineering journal, vol. 6, no. 3, pp 77 84 (2010) 82 reaction is driven in the non spontaneous direction by an external electrical force. the free energy change in an electrolytic cell, or in a non spontaneous cell reaction, is therefore positive and the cell voltage is negative. when the measured value of (ecorr) becomes less negative, the potential of the corresponding galvanic cell becomes less positive, hence the (∆g) value for the corrosion process becomes less negative, and the process is thus less spontaneous. the results of ∆g shown in table (3) indicate that the change in free – energy takes the following sequence: ∆g (j/mol) oxalate > na2co3> tartarate >naoh> ch3cooh >h3po4>nacl table 3, thermodynamic and kinetic function values for corrosion of ti-6al-4v alloy in different media. medium free-energy values -∆g(j/mol) rate of corrosion r mpy nacl 57228.36 938.9 sodium tartarate 508477.8 110.6 naoh 397271.2 79.4 sodium oxalate 511141.2 52.2 acetic acid 284404.8 44.227 phosphoric acid 247001.4 44.2 na2co3 509211.2 42.48 the negative sign of ∆g value refer to spontaneous of the corrosion reaction and the corrosion in (oxalate solution) in most spontaneous compared with other media. 3.4. rate of corrosion (rmpy) any factor that enhances the value of (icorr) results in enhanced value of the corrosion rate on pure kinetic ground. the kinetic parameters were obtained from the corrosion current densities and their dependencies on temperature using the following relationship [8, 9]: rate (mpy) = 0.13 icorr (e/p) …(10) where: rmpy: is the rate of corrosion in (mil/year). icorr : is corrosion current density (µa/cm2). e: equivalent weight of metal or alloy (gm). p: density of metal or alloy (gm/cm3). the results of rate of corrosion were listed in the table (3) which takes the following sequence: r(mpy) nacl > tartrate > naoh > oxalate > ch3cooh >h3po4 > na2co3 4. conclusion from the results of studing the corrosion of ti6al-4v alloy in different media by using electrochemical process at room temperature it can be concluded: 1. the corrosion of ti-6al-4v alloy in sodium oxalate solution has highest negative value of corrosion potential which was thermodynamic parameter. 2. the corrosion of ti-6al-4v alloy in nacl solution has highest value of corrosion current density which was kinetic parameter. 3. the corrosion of ti-6al-4v alloy in nacl solution has lowest value of polarization resistance. 4. the corrosion process of ti-6al-4v alloy in sodium oxalate solution more spontaneous than other media accordance with ∆g calculation (thermodynamic function). 5. the corrosion rate of ti-6al-4v alloy in nacl solution is the highest among the other media (kinetic function). 5. references [1] john f. mccab, anderson`s, applied dental materials / blackwell scientific publications, 1985. [2] smith bj,ducheyne p,transitional behavior in ti-6al-4v fretting corrosion , pages 12 published : jan 1996 ,source ; stp1272-eb . [3] latifa kivnani and abdelilah, corrosion inhibition of titanium in artificial saliva containing fluoride, equip ď electrochimic et matēriaux inorganiques marco chtainia@yahoo.fr, 2004. [4] m. nakagawa, s. matsuya, t. shiraishi and m. ohta, journal of dental research, vol. 78, 1568-1572, 1999 this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ majid h. abdulmageed al-khwarizmi engineering journal, vol. 6, no. 3, pp 77 84 (2010) 83 [5] http:/ www. astm, org/ digital_library/ stp/ source_ pages/stp 1272. htm, p11, 2007. [6] heitz e. and schwenk w., br.corrosion j., vol.11, no.2, 1976. [7] shreir l.l. “corrosion”, metal/environment reactions, second edition vol.1, 1976. [8] saleh j.m., al-shama l. m., and hikmat n.a., corrosion sci., vol.27,pp.22, 1987. [9] saleh j. m., saleh k. a., and hikmat n. a., iraqi j. sci., vol.36, pp.803, 1995. . . this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ )2010( 84 -77 ، صفحة3، العدد 6مجلة الخوارزمي الھندسیة المجلد ماجد حمید عبدالمجید 84 في اوساط مختلفة ti-6al-4vسلوك التأكل لسبیكة ** سالفھ إسماعیل إبراھیم * ماجد حمید عبد المجید الجامعة التكنولوجیة/ قسم ھندسة المواد * majed_hamed60@yahoo.com : البرید االلكتروني الجامعة التكنولوجیة/ مركز بحوث الطاقة والوقود ** الخالصة منت ) ti-6al-4v(البحث تم دراسة سلوك التآكل لسبیكة افي ھذ ة تض اط مختلف ي اوس باستخدام القیاسات الكلفانیة الساكنة في درجة حرارة الغرفة وف ودیوم . ) ، الخسجِقالنباتي، وأغلفة الزبد الالھالم، المستخدم في (وترترات الصودیوم ) ملح الطعام(كلورید الصودیوم ھ (واوكزاالت الص ي الفواك ود ف الموج روب (وكاربونات الصودیوم ) الموجود في مشروب الببسي(وحامض الفسفوریك ) الموجود في الخل(وحامض الخلیك .) و الخضروات ،الخ الموجودة في مش . وھیدروكسید الصودیوم لغرض المقارنة) السفن اب ي تم تفسیر متغیرات التآكل المحسوبة االت ھ ادة االوكس ل ان م د التاك ائج جھ ت نت لھذه األوساط والتي تتضمن جھد التآكل وكثافة تیار التآكل، حیث بین واد ة الم ن بقی ة . االكثر تأكًال في حین اظھرت نتائج كثافة تیار التاكل بان كلورید الصودیوم ھو االكثر تأكًال م ة واالنودی ل الكاثودی ول تاف ائج می تخدام نت م اس ت : المستخدمة في مجال طب االسنان وكانت النتائج كما یلي ti-6al-4vلحساب مقاومة االستقطاب لمعرفة المواد االكثر تأثیرًا على سبیكة na2co3 >oxalate >h3po4 >ch3cooh >naoh >tartrate >nacl ة اط المختلف ي االوس ل ف رعة التآك ا . كما تم حساب التغیر في الطاقة الحره وس ت نت دة بین ل بوح رعة التآك دل س اب مع نة (ئج حس ل س ل لك ذ ) م ا تأخ بأنھ . na2co3< :التسلسل التالي nacl>tartrate>naoh>oxalate>ch3cooh>h3po4 this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 4, no. 2, pp 7682 (2008) semi-active damping of mechanical vibrating systems using variable stiffness actuator yarub omer naji al-azzawi mechatronics engineering department al-khwarizmi college of engineering/ university of baghdad baghdad/iraq (received 19 julay 2007; accepted 14 april 2008) abstract in this research, a variable stiffness actuator is proposed to enhance the damping of the mechanical vibrating system. the frequency response analysis of the vibrating system is dependant in order to analyze and synthesis this semi-active damping, where the suggested process is using active filter to estimate the present frequency of the vibration system, and this will limit the value of the stiffness of the vibrated system. two active filter s are needed, low-pass-filter (lpf) to choose the higher stiffness of the actuator at small frequencies as well as more damping and high-pass-filter (hpf) to choose the lower stiffness of the actuator at high frequencies as well as more damping, and so the result will be good damping as a wholre. these smart systems and others will increase the importance of the mechatronics systems. this job has a case study to explain the semi-active damping system proposed. keywords: semi-active system, vibrations damping, active filters, variable stiffness actuator 1. introduction the mechatronics system really was developed to make the mechanical systems more intelligent [1]. during the last few years, a great efforts had been spent and yet to damp-out the vibrations of the mechanical systems because of the strength limitations of most parts of these systems [2], but the matter is just mitigating them. one of these efforts is the semi-active damping that who differ from the passive damping throughout having a modification property and differ from active damping throughout making the required damping without needing an external energy to make it. semi-active systems are dependent systems now days [3]. here, in this research, the ability of variable stiffness spring is exploited to develop an adaptive damping to the vibrated systems. this spring is added to a spring-mass-damper, and depending on the frequency response characteristics of this system, then decide the overall stiffness of the system depending on a predefined response criterion. a. abu hanieh et al. 2002 show that as future astronomic missions will require more and more stringent resolution requirements, the high demand for an environment clean of vibrations and disturbance appears. this also leads to the need for high precision steering devices for fine pointing of sensitive optics with the highest possible accuracy. several methods exist to reduce vibration levels: the first consists in isolating the sensitive system from the perturbation and the second in damping the structure vibration modes. therefore, two stewart platforms have been designed, manufactured and tested. the first is a soft hexapod that provides 6 degree-of-freedom (dof) active isolation and the second is a stiff hexapod that provides active damping to whatever flexible payload attached/mounted to it. in addition, both hexapods have steering capabilities. lawrence j. alder and stephen m. rock 1993 explain the goal to develop control techniques that provide precise high-bandwidth end-point control of flexible-link manipulators, while simultaneously damping any internal oscillations of the payload. yarub omer naji al-azzawi al-khwarizmi engineering journal, vol. 4, no. 2, pp 76-82 (2008) 77 ronald h. w. hoppe et. al. 2002 show that the new generation of electrorheological fluids (erfs) offers a wide range of applicability in fluid mechatronics with automotive erf devices such as erf shock absorbers mentioned at first place. the optimal design of such tools requires the proper modeling and simulation both of the operational behavior of the device itself as well as its impact on the dynamics of the complete vehicle, this research addresses these issues featuring an extended bingham fluid model and its numerical solution as well as substitutive models of viscoelastic-plastic system behavior. also control issues for optimal active suspension of vehicles with controllable erf shock absorbers are discussed. maria a. heckl and i. d. abrahams 1996 introduce an active control technique that combats oscillations driven by dry friction forces. dry friction can act as the excitation mechanism for some high amplitude oscillations; curve squeal from trains is a well known and notorious example. another, more elementary, example is the oscillation of a mass spring system sliding on a moving belt. a model which predicts the stability behavior of this system is presented. the model is then extended to include an active control system. genda chen, and derek smith 2002 show that a piezoelectric wedge actuator (pwa) is proposed to improve the seismic effectiveness of a passive tuned mass damper (tmd). a pwa is composed of a thin aluminum plate and two piezoelectric sheets bounded on the aluminum plate. the actuator is connected in series with a tmd and it is used as a variable stiffness device or a damping unit regulated with applied voltage. several control algorithms are considered. numerical results indicate that a pwa is effective for a light mass damper and rapidly ineffective as the weight of the damper increases. 2. hardware description 2.1. the mechanical system f(t)= force excitation (n) m= mass (kg) k=original stiffness (n/m) ka= actuator stiffness (n/m) c= damping coefficient (n-sec./m) x(t)= vibration response (m) x(t) ka c f(t) fig. 1. mechanical system. the free-body-diagram to figure(1), is: x˚˚ kx kax cx˚ f(t) )1.....(..........).........()( tfxkakxcxm xmf     assume that the system is excited harmonically. where f(t)=fo sin wt………………..…….. (2) hence the vibration response will be )3.......(....................).........sin()(   txotx where: )4......(.......... )(])[( 222  cmkak fo xo   equ. (4) is the required mathematical model to analyze the frequency response to the mechanical vibrating system. 2.2 electrical filters two types of active filters are used in this research they are low-pass-filter(lpf) with cuttoff frequency ωc and high-pass-filter (hpf) with the same cut-off frequency ωc .the lpf and hpf are shown in figure(2), (a) and (b) respectively [9]. m k m yarub omer naji al-azzawi al-khwarizmi engineering journal, vol. 4, no. 2, pp 76-82 (2008) 78 r2 c1 r1 r3 vi c2 vo (a) lpf c2 r1 c1 c3 vi r2 vo (b) hpf fig. 2. active filters. the transfer function of the lpf is [9 ]: )5..( 1121 1 2 3 21 12 2 2121 3 1                 c r rr crcrjccrr r rvi vo the transfer function of the hpf is [9 ]:     )6...( )(1 32122212 2 32212121 2 2121   crcrcrcrjccrrccrr ccrr vi vo   the ideal responses of lpf and hpf are shown in figure(3),(a) and (b) respectively vo/vi vo/vi 1 1 ωc ω ωc ω (a) (b) fig. 3. ideal responses of lpf and hpf. 3. semi-active damping strategy the mechanism of changing the spring stiffness in order to enhance vibration damping is as follow: taking two springs of the extension type as show in figure (4)a, by changing the length of this type of spring, it is possible to change its stiffness [10], and taking two springs in order to get the action of the helical spring, since the extension spring can extend only and cannot be compressed, at the same time, the type of the spring required in the vibration systems must be of the helical type [1]. changing the length of these types of springs must be occur without changing the setting location of the mass of the vibration system, and that may be happened by connecting the two mentioned springs as shown in figure (4) b. fig. 4. (a). a schematic of an extension spring. x(t)=xo sin(ωt-ф) f(t)=fo sinωt c the two extension springs (i.e. ka) fig. 4. (b). spring-mass-damper system showing the two additional extension springs. from figure (4) (b), the purpose of the servomotor is to change the length of the two extension springs (i.e., the developed helical spring), and thus change the spring stiffness as it is required to get dam ping required. note here, that each of extension springs must be initially stretched to have an initial length (that mean initial stiffness) to prevent the spring looseness cases as show in figure (5). k m yarub omer naji al-azzawi al-khwarizmi engineering journal, vol. 4, no. 2, pp 76-82 (2008) 79 looseness fig. 5. schematic of the system showing the looseness. also there must have mechanical stops to prevent the vibration responses from moving or rotate the servo-motor. now the overall semi-active damping system can be explained in the simulation flow diagram shown in figure(6): f(t)=fo sinωt x(t) accelerometer c left turn right turn fig. 6. simulation flow diagram of semi-active damping system. from figure(6), the accelerometer senses the harmonic signal of the vibration, and this signal which is assumed as sine wave signal with its frequency will be input signal to the two active filters, and depending on the cut-off frequency of each filters, the signal will passed through either lpf or hpf, where if the frequency is low respectively, the signal will pass through the lpf and through the driver shown that will turn the motor left to increase the length of the extension spring (i.e. increasing its stiffness). and if the frequency of the signal is high respectively, it will pass through the hpf and through other driver that will turn the motor right to decrease the length of the extension spring (i.e. decrease its stiffness). here in this research since there are two constant motion to the motor (either full right or full left), then the control strategy that established here is by using bang-bang algorithm [11], which is meaning two states only to the control signal. 4. case study assume a spring-mass-damper system shown in figure(6) with the following selected components: m= 60kg c=50 (ns/m) k=3800 (n/m)     modified (n/m) 1000 valueinitial )n/m( 100 ka f(t)= fo sinωt fo=10 n the mathematical model:   222 )50(60)3800( 10    ka xo the frequency responses when ka=100n/m and 1000n/m are shown clearly in figure(7). fig. 7. frequency responses of the proposed system when ka=100 and 1000n/m. the process is to select the better response at the given frequencies. from figure(7), it is clearly shown that the response with ka=1000n/m is better than the response with ka=100n/m if the frequencies are ≤ 8.5 rad/sec (or 53.4 hz), whereas the response with ka=100n/m is better than the response with ka=1000n/m if the frequencies are ≥ 8.5 rad/sec. so, since the proposed active lpf and hpf filters are responsible of the selection, therefore the cut-off frequency for each one must be ωc= 8.5 rad/s (or. 53.4 hz). also assume an ideal lpf and hpf. lpf hpf driver driver servo motor m k yarub omer naji al-azzawi al-khwarizmi engineering journal, vol. 4, no. 2, pp 76-82 (2008) 80 now when the frequencies of the vibration signal that sensed by the accelerometer is ≤ 8.5 rad/sec, the lpf will be activated and hence the the response with ka=1000n/m will be selected, and when the frequencies exceed the 8.5 rad/sec, the hpf will be activated and hence the response with ka=100n/m will be selected, and so there will have been the modified response which is the better one. 5. results and discussion the results of the previously assumed semiactive damping system are clearly shown in the table(1). table 1 the vibration response when ka=100 and 1000n/m and the modified response. frequen cy ω (rad/sec) response xo(m) when ka=100n/ m response xo(m) when ka=1000n/m modifie d respons e xo(m) 0 0.0026 0.0021 0.0021 2 0.0027 0.0022 0.0022 5 0.0041 0.0030 0.0030 7 0.0098 0.0053 0.0053 8 0.0247 0.0096 0.0096 8.5 0.0160 0.0160 0.0160 9 0.0094 0.0220 0.0094 10 0.0046 0.0077 0.0046 11 0.0029 0.0040 0.0029 15 0.0010 0.0011 0.0010 it is clearly from table(1), that the modified response which is the response of the proposed semi-active damping system is very good response where it have a more damping than the two other responses which are without modification. the process is seems to be as a selection process to the better response values from the other two responses. the modified response is shown in figure (8). fig. 8. frequency response showing the modified response. as shown from fig.8. it is clearly that with the semi-active damping technique, it is possible to have more and more damping depending on the ability of the variation in spring stiffness. 6. conclusion the implementation of the semi-active damping system in hardware has been proven theoretically to be beneficial for intelligent systems requiring fast control response, and the simplicity of the proposed control system in this research had improved the speed of response of the damping to the vibrated system at steady-state. that is due to the hardware (not software) design. also the new idea of using the active filters approved its ability to pick-up the signal of the required frequency, and this idea may be develop to enhance the overall system performance. the flexibility of the system here is limited due to the hardware design rather than software, but at the same time the system is more durable. 7. references [1] donald gibson, “ mechatronics” graw-hill 2001. [2] markus j. hochrainer “investigation of active and passive tuned liquid column dampers for structural control” institute of rational mechanics/ austria, 2002. [3] swaroop k.yalla, ahsan kareem and jeffery .kantor “semi-active tuned liquid column dampers for vibration control of structures “ engineering structure 23, 2001. [4] a. abu habieh, m. horodinca & a. preumont. n.loix & j.ph. verschueren, “stiff and soft stewart platforms for active yarub omer naji al-azzawi al-khwarizmi engineering journal, vol. 4, no. 2, pp 76-82 (2008) 81 damping and active isolation of vibrations”, actuator 2002, 8 th international conference on new actuators, 10-12 june 2002, bremen, germany. [5] lawrence j. alder and stephen m. rock, “adaptive control of a flexible-link robotic manipulator with unknown payload dynamics”, the american control conference, san francisco, ca, june 1993. [6] ronald h. w. hoppe, george mazurkevitch, uwe rettig, and oskar von stryk, “modeling, simulation, and control of electrorheological fluid devices”, university of augsburg, inst. of. math., d-86159 augsburg, germany.2002. [7] maria a. heckl and i. d. abrahams, “active control of frictiondriven oscillation”, journal of sound and vibration 193(1), 417-426, 1996. [8] genda chen and derek smith, “efficiency of piezoelectric wedge actuators for fine tuning of mass dampers in structural applications”, 15 th asce engineering mechanics conference. june 2-5, 2002. [9] j. millman, “ microelectronics “ , graw-hill 2000. [10] lawrence b. tentor, “characterization of electromagnetic tuned vibratio absorber “ dissertation submitted to the faculty of the virginia polytechnic institute and state university in partial fulfillment of the requirements for the degree of doctorate of philosophy in mechanical engineering,2001. [11] christopher t.kilian, “modern control technology; components and systems” graw hill, 2001. yarub omer naji al-azzawi al-khwarizmi engineering journal, vol. 4, no. 2, pp 76-82 (2008) 82 لميكانيكية اإلهتسازات األنظمة لشبه فعال اإلخماد ا جهاز متغير الجسائةستخذام إب ٌعزب عًز َاجً انعشأي جايعح تغذاد/ كهٍح ُْذسح أنخٕارسيً/قسى ُْذسح أنًٍكاتزَٔكس الخالصة تذهٍم األستجاتح انتزددٌح نُظاو األْتشاس تى .جٓاس يتغٍز انجسائح تى اقتزادّ نتذسٍٍ األخًاد نُظاو األْتشاس انًٍكاٍَكً، فً ْذا انثجث نتخًٍٍ انتزدد active filters دٍث اٌ انعًهٍح انتً تى اقتزادٓا ًْ تاستعًال ال ، اعتًادِ يٍ اجم تذهٍم ٔ تزكٍة َظاو األخًاد انشثّ فعال ألختٍار انجسائح األعهى (lpf)طهٕتح ًْا ال active filtersاثُاٌ يٍ ال . ْٔذا سٍذذد قًٍح انجسائح نُظاو األْتشاس،انذانً نُظاو األْتشاس ألختٍار انجسائح األقم نهجٓاس فً انتزدداخ انعانٍح جٍذا كاخًاد (hpf)ٔ ،نهجٓاس فً انتزدداخ انصغٍزج تشكم جٍذ كًا ْٕ األخًاد األكثز كًا ٔ ٌتضًٍ انعًم دراسح دانح mechatronics.تهك األَظًح انذكٍح ٔ غٍزْا ستشٌذ يٍ اَظًح ال. ْٔكذا انُتٍجح ًْ تخًٍذ جٍذ .أكثز .نتٕضٍخ َظاو األخًاد انشثّ فعال انًقتزح (microsoft word 10-22\332\341\355 \332\341\346\307\344) al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 15, no. 4, december, (2019) p. p. 1022 modeling of bending properties of stainless steel 304 sheets welded by tungsten inert gas welding process ali hussein alwan department of mechanical engineering/ university of technology email: 20145@uotechnology.edu.iq (received 23 may 2019; accepted 25 september 2019) https://doi.org/10.22153/kej.2019.09.003 abstract in this research, the effects of both current and argon gas pressure on the bending properties of welded joints were studied. using the possible ranges of welding gas pressures and currents, tungsten inert gas welding (tig) of stainless steel (304) sheet was used to obtain their influence on the maximum bending force of the (tig) welded joints. design of experiment (doe) ‘version 10' was used to determine the design matrix of experiments depending on the used levels of the input factors. response surface methodology (rsm) technique was used to obtain an empirical mathematical model for the maximum bending force as a function of welding parameters (current and argon gas pressure). also, the analysis of variance (anova) was used to verify the adequacy of the resulted model statistically. keywords: bending properties, numerical optimization, stainless steel (304), tig welding, welding parameters. 1. introduction welding is a critical process in the industry since it used to join different materials, especially stainless steels, which are presently used in various structural engineering parts. welding of tungsten with inert argon gas (tig) is one of the most important and common industrial processes. the weld efficiency is related to the best selection of main welding parameters, such as welding speed, current, filler material and welding gas pressure. in this section, a review of tig welding research, welding parameters, the effective welding parameters, type of electrode, covering gases, and welding speed are illustrated. anand et al.[1] showed that the tig welding current 120 a and 309l welding filler produced a higher tensile strength and maximum bending force of the welded joints 310 stainless steel. tabish et al. [2] concluded that the tensile strength of the stainless steel 304 plate tig joined specimens was higher than the base material, and the use of low heat input resulted in the best tensile strength and hardness results than other. navid et al.[3] investigated the heat input in the tig welding process of 316 stainless steel sheet. it was shown that the increase of current tends to increase the amount of heat input in the welding zone, and this leads to the enlargement of depth and width of the welding pool. hussein et al. [4] used the (rsm) to develop the mathematical model of tig welding parameters and the output of the joint strength of 304 stainless sheets. it was shown that 50 a current with 1.6 mm welding filler size and low gas flow rate produced finer weld microstructure without crack, and this leads to high tensile strength of joint. vikarm and sharma [5] showed that the lower welding speed range of stainless steel 430 joined by tig welding produced a higher tensile strength as a result to the formation fine dendritic matrix in the weld zone microstructure. rohit et al. [6] used the voltage, current, gas flow rate, and welding speed as the input parameters of 304 stainless steel sheets joined by tig welding. it was ali hussein alwan al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 1022 (2019) 11 concluded that the neuro-fuzzy inference system for the prediction of tensile properties of welded specimens indicated the accuracy over other the prediction concept (hardness property). current, welding speed and the flow rate of welding gas were selected by ravichandran et al. [7] to analyze the tig welding of duplex stainless steel using signal to noise ratio and (anova). the analysis showed that the flow rate of welding gas was the most important parameter for the hardness of welded joint and impact strength properties. aamir et al. [8] concluded that the tensile strength of welded specimens increased with increasing tig welding pulse current. the increasing of filler feed rate without control of welding current leads to decrease welding strength. saha and dhami [9] concluded that the combinations of optimum tig welding parameters (current, flow rate of gas, speed, and diameter of the electrode) of 304 stainless steel welded joint for tensile properties and hardness only differed in term of welding current. it was found that the optimum value of tensile strength resulted at (180 amp.), whereas the optimum hardness was at (150 amp.). the optimization of tig welding parameters using taguchi and anova approach of 317 stainless steel plate was investigated by goyal and agrawal [10]. it was manifested that the current and welding voltage have a significant effect on the tensile strength more than gas pressure. jadhav and wasankar [11] used taguchi and anova analysis to obtain the optimum values for tig welding joint hardness and penetration depth of stainless steel 304 that occurred at (150 amp welding current, and 15 l/min of gas flow rate). naik et al. [12] found that the welding filler has a minimum effect on the tensile strength and hardness, whereas the welding current has maximum influence on the tensile strength and energy impact of stainless steel 2205 plates joined by tig welding. bayrak et al. [13] determined that the decreasing amount of heat input during tig welding has a positive influence on the mechanical properties of (304 l) stainless steel joint due to the prevented chromium carbide precipitation. from the above literature, it has been shown that most of the research works focused on the (tensile properties, heat input, corrosion resistance, material of welding filler, and microstructure, etc.) of the joint using tig welding. also, some researchers investigated the optimization of welding parameters by using (taguchi and anova), but a few research considered the use of rsm and analysis of variance (anova) within the design of experiments program. in addition, a few studies considered the modeling of maximum bending force. for this purpose, the aim of the present work is to build a model for the maximum bending force of 304 stainless steel sheets joined by tig welding and using (doe) with rsm technique and anova analysis to obtain an empirical equation for the maximum bending force at the optimum welding parameters (current, and gas pressure) by numerical optimization. confirmation tests will be done at using the optimum input parameters to compare the experimental results with the theoretical ones. 2. method 2.1. selection of material and specimens preparation the sheet of 304 stainless steel alloy was used in the present work which was obtained from the industrial market of (2.0 mm) thickness. the chemical composition of the worked alloy is listed in table (1) according to the astm (a240) standard of material [1٤]. the sheets were cut to prepare the required dimensions of welding specimens (200 mm×100 mm) by an electronic cutting machine, and the edges of sheet were ground to ensure that there is no gap between the two mounted specimens, as shown in figure (1). table 1, chemical composition of stainless steel 304 alloy. [14]. element w.t.% element w.t.% c 0.08 si 0.750 p 0.0450 ni 8.0 mn 2.0 n 0.1 s 0.03 mo cr 18 fig 1. weld specimen’s preparation. ali hussein alwan al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 1022 (2019) 12 2.2. procedure of welding process the welding process was done manually by a skilled technician welder in the university of technology / workshop center. to be sure that the two sheets are to be welded in alignment together during the welding process, the sheets were tightly and clamped on the welding board, as explained in figure (2). the tig 160 welding machine model was used in the present work to accomplish welding of sheets, as shown in figure (3). table (2) shows the welding machine technical data and welding tools. through the welding process, the argon gas was used as the inert gas, and the gas flow rate can be manually adjusted by the argon gas organizer, as shown in figure (4). the material of welding filler 304 was used in this work because it is appropriate with the welding specimens material stainless steel 304. the main parameters of welding (current and welding gas flow pressure) were chosen to obtain the best quality of welded joints with a high welding efficiency, i.e., high mechanical and bending properties. fig. 2. workpiece sheets before and after welding process. fig. 3. tig 160 welding machine. fig. 4. organizer of argon gas. table 2, the welding machine technical data power factor. 0.690 circuit voltage. 65.0 – 80.0volt circuit power. 30watt diameter of tungsten electrode 1.60 mm diameter of welding filler rod 1.60 mm 2.3 experimental design matrix the doe procedure included making mathematical model for the response (max. bending force) in term of input parameters (current and gas pressure), statistical analysis by anova in order to find the model significant or not within 95 percent confidence level, and finding the optimum output (max. bending force) at the optimum input by numerical optimization. finally, confirmation test is conducted at the optimum conditions for validation purpose in term of the error between the experimental and theoretical result. in this research, design expert computer programing with the technique of response surface methodology (rsm) was employed to build the matrix of input parameters. the used input parameters in the experimentation processes were selected depending on the previous ali hussein alwan al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 1022 (2019) 13 experience research. table (3) lists these factors with two levels. the experimental design was conducted by rsm for two input factors and four responses outputs, with five and four center and axial points, respectively using central composite rotatable design. according to the design of the experimental matrix, thirteen practical runs were performed. two coded levels (−1 and +1) were used for each parameter, where each code stratifies with a real value tantamount. thus, welding gas flow pressure and current were the studied input parameters in this work. the input parameters data in terms of real factors are presented in table (4), which explained the used experimental design matrix. table 3, levels of input parameters used with coding. 2.4 mechanical properties tests 2.4.1 tensile test process. in the present research, tensile tests were performed in university of technology/ laboratories of mechanical engineering department. tinius olsen universal testing machine which has a maximum capacity of (5 kn) was used to conduct the tensile test of specimens. a cnc milling machine was used to make the tensile specimens, and the tensile test was restricted according to the american society for testing and materials specifications (astm). figure (5) depicts the geometry design of tensile specimen dimensions for standard (asem e8-m) [15]. to evaluate the tensile properties of each welding joint, the average of three specimens was taken in a perpendicular orientation to the welded line and tested at a constant crosshead speed of (1 mm/min) for each case of welding experiment, figure (6). the obtained result of tensile strength, yield stress, and elongation of the welded joint specimens are given in table (4). fig. 5. rectangular cross-section tensile test specimen according to astm e8-m. [1٥] all dimensions are in millimeters. fig. 6. tensile test specimens. 2.4.2 bending test process the bending test was done by tinius olsen universal testing machine. the test was achieved at room temperature with a compression speed of (1mm /min). the type of three_ point bending test was used in the present work to evaluate the factors units low level range (-1) high level range (+1) pressure of gas flow kg.f/cm2 13.0 15.0 welding current amp. 80.0 100.0 ali hussein alwan al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 1022 (2019) 14 maximum bending force. the average of three specimens of each welding case was taken in a perpendicular orientation to the welding line, as revealed in figure (7). the bending test was restricted according to the american society for testing and materials specifications (astm e 190) [16]. fig. 7. bending specimen. 3. results and discussion. 3.1 tensile and bending test results. after performing the experiments, the welded joints section were examined visually, and the proper portion of the weld surfaces was selected to prepare the tensile and bending specimens. table (4) shows the results of tensile and bending tests. the tensile strength and maximum bending force of the received base material are 622 mpa and 410 n, respectively. the maximum yield stress was obtained at gas pressure (16 kgf/cm2), and current (90 amp.). while the ultimate tensile stress and elongation were obtained at gas pressure (15 kgf/cm2), and current (80 amp.). table 4, design matrix experimental for actual input factors and responses. standard no. run no. gas pressure (kgf/cm2). current ampere. yield stress σy (mpa). ultimate tensile stress σu (mpa). elongation. max. bending force (n) 1 2 13 80.0 240.0 535.0 28 % 360 2 8 13 100.0 298.0 527.0 44 % 592 3 3 15 80.0 335.0 715.0 44 % 683 4 1 15 100.0 270.0 703.0 20 % 600 5 4 14 70.0 272.0 606.0 38 % 589 6 7 14 110.0 272.0 570.0 27 % 535 7 9 12 90.0 268.0 313.0 40 % 485 8 6 16 90.0 320.0 660.0 31 % 755 9 10 14 90.0 285.0 694.0 31 % 487 10 13 14 90.0 285.0 695.0 35 % 490 11 12 14 90.0 298.0 715.0 32 % 587 12 5 14 90.0 300.0 710.0 34 % 548 13 11 14 90.0 290.0 711.0 35 % 565 in table (4), it can be noted that the highest value of tensile stress occurred at higher gas pressure level and almost at the center of current level (90.0) amp. this indicates that the gas pressure has a greater influence on the tensile strength than the welding current due to effect of gas protection which was overcame the influence of the heat input caused by current. this result is in agreement with the previous works especially reference (2) which was found that tensile strength of the stainless steel 304 plate tig joined specimens was higher than the base material, and the use of low heat input resulted the best tensile strength. 3.2 the maximum bending force model. the average response obtained for a maximum bending force was used in calculating the model of the response surface per response by using the least-squares method. for maximum bending force prediction, a diminutive quadratic model in coded terms was analyzed using statistical analysis of variance ali hussein alwan al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 1022 (2019) 15 (anova) with backward elimination of insignificant coefficients. table (5) explains the statistical analysis of variance (anova), which created by the software for the remaining terms. the model is significant at 95% confidence. it is observed that the gas pressure (b), the squared term of gas pressure (b²), and the interaction of current and gas pressure factors (ab) are significant terms with the exception of the current (a), the lack of fit test indicates that a good model was produced. this model explains that only the three terms (b, b², and ab) have the highest effect on the maximum bending force. table 5, anova for response surface two factors interaction model for maximum bending force. the final equation of maximum bending force in terms of the actual factors: maximum bending force = 6662.92284 + 110.59167 * current + 243.54321* pressure -7.87500 * current * pressure + 19.20679 * pressure2 in term of a & b: maximum bending force = 6662.92284 + 110.59167 * a + 243.54321* b 7.87500 * ab+ 19.20679 * b2 for the normal probability plot shown in figure (8) for the maximum bending force data, the residuals that mostly that falling on a straight line implying errors, are normally distributed. and, figure (9) manifests the residuals against the predicted outputs for the results of maximum bending force. also, it can be observed that no clear patterns or unusual structure exists, indicating that the models are accurate. fig. 8. normal distribution of maximum bending force data. design-expert® software maximum bending force color points by value of maximum bending force: 755 360 externally studentized residuals n o rm a l % p ro b a b ili ty normal plot of residuals -2.00 -1.00 0.00 1.00 2.00 1 5 10 20 30 50 70 80 90 95 99 source sum of squares df mean square f value p-value prob f model 97360.56 4 24340.14 11.71 0.0020 significant a-current 140.08 1 140.08 0.067 0.8018 b-pressure 63220.08 1 63220.08 30.40 0.0006 ab 24806.25 1 24806.25 11.93 0.0086 b2 9194.14 1 9194.14 4.42 0.0686 residual 16634.21 8 2079.28 lack of fit 8533.01 4 2133.25 1.05 0.4805 not significant pure error 8101.20 4 2025.30 cor total 1.140e+005 12 std. dev. 45.60 r-squared 0.8541 mean 559.69 adj. r-squared 0.7811 c.v. % 8.15 pred. r-squared 0.6063 press 44880.66 adeq. precision 12.643 ali hussein alwan al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 1022 (2019) 16 fig. 9. residual versus predicted data. the predicted actual maximum bending force data against the actual ones for comparison reason were is depicted in figure (10). figure (11) manifests the perturbation of maximum bending force, which shows the effect of both gas pressure and current on the maximum bending force over the range of the used levels. it was noted that the gas pressure has a greater impact on the maximum bending force than the current which is coded in term (a). however, figure (12) shows the combined influence of the two factors that occur after the central value (at nearly 95 ampere current). fig. 10. predicted versus actual data. design-expert® software maximum bending force color points by value of maximum bending force: 755 360 predicted e x te rn a lly s tu d e n ti z e d r e s id u a ls residuals vs. predicted -6.00 -4.00 -2.00 0.00 2.00 4.00 6.00 400 500 600 700 800 4.23877 -4.23877 0 design-expert® software maximum bending force color points by value of maximum bending force: 755 360 actual p re d ic te d predicted vs. actual 300 400 500 600 700 800 300 400 500 600 700 800 ali hussein alwan al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 1022 (2019) 17 fig. 11. perturbation of maximum bending force. fig. 12. interaction of the gas pressure with the current. figure (13) illustrates the 2d contour graph of maximum bending force as a function of gas pressure and current. from this figure, it can be seen that the increase in gas pressure and current caused an increase in the maximum bending force. it can be noted that the increase of gas pressure value at the case of lower current (80 amperes) leads to a maximum bending force of more than (665 n) because the more safeguard of the weld joint caused by the effect of higher gas pressure. while the increase of the current value (100 amperes) at minimum value of gas pressure (13 kgf/cm2) resulted in more than (560 n) maximum bending force because the higher thermal impact resulted due to the higher quantity of heat input at the maximum current value. from the results above, both gas pressure and current have an influence on the maximum bending force, and the gas pressure has a greater effect on the bending force than the current value when analyzing these factors each one individually. also, regarding the interaction of both factors gas pressure and weld current, also figure (13) shows that at nearly (95 amperes and 14 kgf/cm2). the combined impact of the two factors gives a lower maximum bending force of about 535 n than that caused by each one individually. design-expert® software factor coding: actual maximum bending force ((n)) actual factors a: current = 90 b: pressure = 14 -1.000 -0.500 0.000 0.500 1.000 300 400 500 600 700 800 a a b b perturbation deviation from reference point (coded units) m a x im u m b e n d in g f o rc e ( (n )) design-expert® software factor coding: actual maximum bending force ((n)) design points 95% ci bands x1 = a: current x2 = b: pressure b13 b+ 15 a: current ((amp)) b: pressure ((kgf/cm2)) 80 85 90 95 100 m a x im u m b e n d in g f o rc e ( (n )) 300 400 500 600 700 800 interaction ali hussein alwan al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 1022 (2019) 18 the surface plot was explained in the 3d graph as viewed in figure (14) of maximum bending force as a function of current and gas pressure factors, and it confirms the perception mentioned above in the 2d graph. the increase of both factors current and gas pressure resulted in an increase in the maximum bending force value at their maximum level, while the gas pressure slightly higher, whereas at near their center level, i.e. at its higher level resulted in the maximum value of bending force at a higher level of current. whereas, the lower level of both current and gas pressure caused the minimum value of max. bending force due to the less thermal effects. fig. 13. 2d plot of maximum bending force as a function of current and gas pressure. fig. 14. 3d plot of maximum bending force as a function of current and gas pressure. design-expert® software factor coding: actual maximum bending force ((n)) design points 755 360 x1 = a: current x2 = b: pressure 80 85 90 95 100 13 13.5 14 14.5 15 maximum bending force (n) a: current (amp) b : p re s s u re ( k g f/ c m 2 ) 500 600 630 665 560 560 475 440 525 545 580 535 550 550 5 design-expert® software factor coding: actual maximum bending force ((n)) design points above predicted value design points below predicted value 755 360 x1 = a: current x2 = b: pressure 13 13.5 14 14.5 15 80 85 90 95 100 300 400 500 600 700 800 m a x im u m b e n d in g f o rc e ( n ) a: current (amp)b: pressure (kgf/cm2) ali hussein alwan al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 1022 (2019) 19 3.3 optimization of the maximum bending force the doe numerical optimization software was employed to obtain the optimum values of parameters in order to achieve the desired requirements of the welding joint, depending on the outcomes from the predicted quadratic models for the maximum bending force as responses as a function of two input factors (current and gas pressure). table (6) manifests the constrains of optimization parameters and the goal of the output requirements. table 6, constrains of optimization name goal lower limit upper limit lower weight upper weight importance current (amp) is in range 80 100 1 1 3 pressure (kgf/cm2) is in range 13 15 1 1 3 maximum bending force (n) maximize 360 755 1 1 3 desirability, which is a new objective function, was estimated and to be maximized through a numerical optimization to modify the predicted model, it ranges from 0 to 1 at the desired goal. the greater aim of this optimization was to determine the maximum result response that simultaneously met the variable maximum bending force. constrain of the variable was used for numerical optimization of the maximum bending force, the input factors were selected for their used ranges, while the response was selected to be the maximum. then according to this, it was found that one possible solution satisfied these constrains to determine the maximum values of the maximum bending force (709 n) as illustrates in table (7) with a maximum desirability value of (0.884) at the optimum values of weld current (80amp) and gas pressure (15 kgf/cm2). table 7, the optimum values of input factors and outputs. current (amp.) gas pressure (kgf/cm2) maximum bending force (n) desirability 80 15 709 0.884 3.4 confirmation tests at the optimum conditions for more accuracy and to verify the validation of the maximum values of the maximum bending force shown in table (7), the confirmation tests were done at the optimum values of current and gas pressure. the confirmation tests average results are listed in table (8) for the comparison purpose between the results of experimental and predicted. the maximum error between the experimental and predicted for maximum bending force is about 3.8%. figure (1٥) and figure (1٦) display the position of the maximum bending force in the 2d contour graph and 3d plot of optimum maximum bending force as a function of gas pressure and current, respectively. from these figures, it can be seen that the optimum maximum bending force resulted from the lower level of weld current (80 amperes) and the higher level of gas pressure (15 kgf/cm2). table 8, average results of confirmation tests at the optimum conditions current (amp.) gas pressure (kgf/cm2) exp. maximum bending force (n) pred. maximum bending force (n) error (%) 80 15 683 709 3.8 ali hussein alwan al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 1022 (2019) 20 fig. 15. 2d plot showing the position of the optimum maximum bending force. fig. 16. 3d plot showing the position of the optimum maximum bending force. 4. conclusions the experimental and predicted results show that the increase in both gas pressure and current leads to an increase in the maximum bending force. however, the gas pressure has a greater impact on the maximum bending force than the current. according to the numerical optimization, the maximum value for the maximum bending force is (709 n) with a maximum desirability value of (0.884) at the optimum values of weld current (80 amperes) and gas pressure (15 kgf/cm2). the confirmation tests prove that there is an agreement between the experimental and predicted results with a maximum error of (3.8%) for the maximum bending force. the increase of welding gas pressure increases the tensile strength, and the increase of both input factors (current and gas pressure) individually tends to a visual increase in the yield stress and elongation. also, the combined effect of the input factors almost near their central level data gives the lowest values of the yield stress and elongation. design-expert® software factor coding: actual maximum bending force ((n)) design points 755 360 x1 = a: current x2 = b: pressure 80 85 90 95 100 13 13.5 14 14.5 15 maximum bending force (n) a: current (amp) b : p re ss u re ( k g f/ cm 2 ) 500 600 625 645 570 555 555 545 535 520 475 435 5 prediction 709 design-expert® software factor coding: actual maximum bending force ((n)) design points above predicted value design points below predicted value 755 360 x1 = a: current x2 = b: pressure 13 13.5 14 14.5 15 80 85 90 95 100 300 400 500 600 700 800 m a x im u m b e n d in g f o rc e ( n ) a: current (amp)b: pressure (kgf/cm2) 709 ali hussein alwan al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 1022 (2019) 21 5. references [1] v.a.rao, and dr. r. deivanathan" experimental investigation for welding aspects of stainless steel 310 for the process of tig welding", elsevier procedia engineering, pp. 902 – 908, 2014. [2] t.a.tabish, t.abbas, m.farhan, s.atiq, and t.z.butt, " effect of heat input on microstructure and mechanical properties of the tig welded joints of aisi 304 stainless steel ", international journal of scientific & engineering research, vol .5, issue 7, pp. 1532-1541, 2014. [3] n. moslemi, n. redzuan, n. ahmad, and t. nan hor, "effect of current on characteristic for 316 stainless steel welded joint including microstructure and mechanical properties", elsevier procedia cirp, pp.560 – 564, 2015. [4] h. zuhailawati, m. a. jamaluddin, a. a. seman, and s. ismail, "welding investigation and prediction of tensile strength of 304 stainless steel sheet metal joint by response surface methodology ", elsevier procedia chemistry, pp. 217-221, 2016. [5] vikarm, and p. sharma," influence of process parameters on mechanical property of stainless steel 430 plate by tig and mig welding", international journal for scientific research & development, vol. 4, issue 10, pp. 4045, 2016. [6] i.j. rohit, r. ajithraj and m. dev anand, "experimental analysis of tig welded 304 stainless steel using artificial intelligence tool", international journal of pure and applied mathematics, vol. 116, no. 22, pp. 365-373, 2017. [7] m. ravichandran, a. naveen sait, and u. vignesh, " investigation on tig welding parameters of 2205 duplex stainless steel", international journal of automotive and mechanical engineering, vol. 14, issue 3, pp. 4518-4530, september 2017. [8] a. sohail, abdul aziz, m. imran, o. junaid, and s. ahmed," effect of tig welding parameters on the properties of 304l automated girth welded pipes using orbital welding machine", journal of material science, vol. 5, issue 4, pp.136-143, 2017. [9] m. saha, and, s. s. dhami, "effect of tig welding parameter of welded joint of stainless steel ss304 by tig welding "trends in mechanical engineering & technology, vol. 8, issue 3, pp.18-27, 2018 [10] d. goyal, and p. agrawal," optimization of welding parameters of tig welding on welding strength using taguchi and anova " international journal for research in applied science & engineering technology, vol. 6, issue 3, pp.1250-1255, 2018. [11] a. jadhav, and. k. s.wasankar," optimisation of process parameters of a-tig welding for penetration and hardness of ss 304 stainless steel weld" international research journal of engineering and technology, vol. 5, issue 10, pp.230-324, 2018. [12] a. balaram naik, a. chennakesava reddy, and v. venugopal reddy," an experimental investigation of process parameters of tungsten inert gas welding for improvement of mechanical properties on duplex stainless steel (2205) weldments using design of experiments" journal of mechanical engineering research and developments, vol. 41, no.1, pp.86-96, 2018. [13] m. a. bayrak, v. onar, and a. işıtan," the investigation of microstructure and mechanical properties of austenitic stainless steel joints obtained by different welding methods and different welding parameters" setsci conference indexing system,turkey, vol. 3, pp.324-327, 2018. [14] astm, "standard specification for heatresisting chromium and chromium-nickel stainless steel plate, sheet, and strip for pressure vessels", a240, 2006. [15] astm, "standard test methods for tension testing of metallic materials", e8/e8m – 09, 2006. [16] astm, "standard test method for guided bend test for ductility of welds", e190-92, 2006. )2019( 1022، صفحة 4العدد ، 15دجلة الخوارزمي الهندسية المجلم علي حسين علوان مع التنكستن لحام بعملية الملحومة 304 للصدأ المقاوم الصلب لصفائح االنحناء خواص نمذجة الخامل الغاز علي حسين علوان قسم الهندسة الميكانيكية/ الجامعة التكنولوجية 20145@uotechnology.edu.iq :البريد االلكتروني الخالصة ، تم دراسة تأثير كل من ضغط غاز األركون والتيار على خواص االنحناء للوصالت الملحومة. باستخدام المديات الممكنة لضغوط وتيارات حثفي هذا الب ). tigه على أقصى قوة انحناء للمفاصل الملحومة بلحام () اليجاد تأثير٣٠٤) للفوالذ المقاوم للصدأ (tigغاز اللحام ، تم استخدام لحام غاز التنغستن الخامل ( تم استخدام و اإلصدار العاشر لتحديد مصفوفة تصميم التجارب باالعتماد على المديات المستخدمة لعوامل االدخال ،)doeتم استخدام برنامج تصميم التجارب ( دالة لعوامل اللحام (التيار وضغط غاز بوصفها لالستجابة لقوة االنحناء القصوى ) للحصول على نموذج رياضي تجريبي rsmتقنية منهجية سطح االستجابة ( ) للتحقق إحصائياً من مالئمة النموذج الناتج.anovaستخدام تحليل التباين (أيضاً أتم واألركون) ٦٣ alkhwarizmi engineering journal laminar natural convection of newtonian and non – newtonian fluids inside triangular enclosure dr. ala′a abbas muhadi mech. eng. dept. university of kufa (received 31 july 2006 ; accepted 19 december 2006) abstract in the present work, steady two – dimensional laminar natural convection heat transfer of newtonian and non-newtonian fluids inside isosceles triangular enclosure has been analyzed numerically for a wide range of the modified rayleigh numbers of (103 ≤ ra ≤ 105), with non-dimensional parameter (ne) of prandtl – eyring model ranging from (0 to 10), and modified prandtl number take in the range (pr* =1,10, and 100). two types of boundary conditions have been considered. the first, when the inclined walls are heated with different uniform temperatures and the lower wall is insulated. the second, when the bottom wall is heated by applying a uniform heat flux while the inclined walls at the constant cold temperature. also, the non-newtonian fluids under consideration were assumed to obey the prandtl – eyring model..the results are presented in terms of isotherms and streamlines to show the behavior of the fluid flow and temperature fields. in addition, some graphics are presented the relation between average nusselt number and the various parameters. the results show the effect of non – dimensional parameter (ne) on the velocity and temperature profiles. they also show that the average nusselt number is a strong function of modified rayleigh number, modified prandtl number, non-dimensional parameter, and the boundary conditions. four different correlations have been made to show the dependence of the average nusselt number on the non-dimensional parameter, the modified rayleigh and prandtl numbers. keywords: natural convection – non-newtonian fluids – triangular enclosures finite differences method. alkhwarizmi engineering journal vol. 3 , , no. 1, pp63 – ٩٣ ( 2007) this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. ala′a abbas muhadi /al-khwarizmi engineering journal ,vol.3, no.1, pp 63-80 (2007) ٦٤ nomenclature a.&.b : fluid consistency indices for the prandtl – eyring model (kg/m.s2) & (s) g : gravitational acceleration (m/ s2). h : heat transfer coefficient (w /m2. k ). k : thermal conductivity of fluid (w/m. k ). l : width and height of enclosure (m). lc : length of the inclined wall (m). ne :fluid index of prandtl – eyring model 2l bα  . nu : nusselt number = )( ch ttk ql  . nua : average nusselt number . p : pressure (pa). pr : prandtl number = (υ /α). pr* : modified prandtl number = αρ ab o . q : heat flux (w /m2). ra : modified rayleigh number =          b.c.2for b.c.1for )( αkab βlρ nurara abα ttβlρ ra 4 o e * e ch 3 o e qg g t : temperature (k). u : fluid velocity in x-direction (m/s). v : fluid velocity in y-direction (m/s). x& y : cartesian coordinates. greek symbols α : thermal diffusivity (m2/s). β : thermal expansion coefficient (1/k ). f : any arbitrary function, f (x,y). δt : temperature difference (k). yx δδ & : regular grid size in the x and y directions, respectively (m). rr yx δδ & : irregular grid size in the x and y directions, respectively (m). θ : dimensionless temperature = k ql tt tt tt c ch c             b.c.2for b.c.1for μ : dynamic viscosity, (kg/m.s). υ : kinematic viscosity of fluid (m2/s). ρ : density (kg/m3). xxτ : normal stress in the x direction. yxτ : shear stress (pa) =             luidnewtonianffornon anfluidfornewtoni ) y u bsinha y u μ 1( yyτ : normal stress in the y direction. ψ : stream function (m2/s). ω : vorticity (1/s). 1. introduction natural convection in enclosures, has been extensively studied due to it’s wide ranging applications such as building insulation, solar cavity receivers, ventilation of rooms, storage of grease, mineral oil, or crude oil in containers, nuclear reactor insulation, crystal growth in liquids, and the cooling of electrical components [1]. however, the efforts have been mainly directed toward the investigation of convection in rectangular enclosures, which may be leveled or tilted. relatively, very little this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. ala′a abbas muhadi /al-khwarizmi engineering journal ,vol.3, no.1, pp 63-80 (2007) ٦٥ attention is focused on the study of natural convection in triangular enclosures. in the present work, a numerical study is performed to analyze the natural convection heat transfer of newtonian and non – newtonian fluids inside triangular enclosure under two different cases of boundary conditions. the fluid motion and heat transfer are affected by modified rayleigh number, modified prandtl number, and non – dimensional parameter (ne) of prandtl – eyring model. the non – dimensional parameter (ne) determines the nature of fluid, that is, newtonian (ne = 0) and non – newtonian fluids (ne > 0). the mass, momentum, and energy conservation equations, which are considered to describe the fluid flow and heat transfer for natural convection are nonlinear and because of this non linearity, some difficulties have arisen in numerical as well as in analytical studies [2]. one of the greatest difficulties with the numerical studies is the problem of divergence of the iterative methods since an analytical solution of the actual problem is extremely difficult, if not possible, a number of assumptions together with the computational fluid dynamic techniques are used to obtain approximate results [3]. 2. mathematical formulation : the schematic of the physical model and the coordinate system are shown in fig.(1). it is isosceles triangular region of width (l) and height (l) under two different cases of thermal boundary conditions, these boundary conditions are: case(i) : the inclined walls are heated with different uniform temperatures ( ch tt & ) and the lower wall is perfectly insulated (b.c.1), as shown in (fig.1a). case(ii) : the lower wall is heated by applying a uniform heat flux (q) and the inclined walls are isothermally cooled ( ct ) (b.c.2), as shown in (fig.1b). density is also considered as constant value but for buoyant term it is linearised by relation: )]([ oo ttβρρ  1 were β is thermal expansion coefficient for temperature ot . the depth of the region is assumed to be sufficiently large so that the flow and the heat transfer are two dimensional. the fluid considered is non – newtonian and the flow laminar. for the present physical model, subject to the boussinesque approximation, the governing equations in their primitive form, are given by: 0      y v x u y τ x τ x p y u v x u uρ yxxx o               )( ρg y τ x τ y p y v v x v uρ yyxy o                )( )( 2 2 2 2 y t x t α y t v x t u            in the above equations, (u, v, α, p, t ) are the fluid velocity components, the thermal diffusivity, the pressure and the temperature. in fact eqs.(2 to 5) are system of partial differential equations. they are the base for natural convection phenomenon for 2d (1) (2) (4) (5) (3) this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. ala′a abbas muhadi /al-khwarizmi engineering journal ,vol.3, no.1, pp 63-80 (2007) ٦٦ enclosures, presented by mass, momentum and energy conservation equations. as was mentioned in ref.[4], the prandtl – eyring model for non – newtonian fluids can be represented as: )( y u b sinhaτ    1 hence, the shear stresses: )( x u b sinhaτ xx    12 )( y v b sinhaτ yy    12 )]1 x v y u b sinhaττ yxxy        ([ where a and b are the fluid consistency indices for the prandtl – eyring model. since it proves to be more convenient to work in terms of a stream function and vorticity, the stream function ψ(x,y) is introduced in the usual manner: y ψ u    & x ψ v    it is evident from eq.(10) that the stream function satisfies the continuity equation identically. further more, for this plane flow field, the only non – zero component of the vorticity is: y u x v ω       combining the definition of vorticity and the velocity components in terms of the stream function, and cross – differentiating the eqs.(3) and (4) to reduce the number of equations and eliminate the pressure terms, and substituting for (ρ) from eq.(1), a new set of equations is obtained with independent variables ψ, ω and t: -ω y ψ x ψ       2 2 2 2 g 321 2 2 2 2 o s] x s 4 y s x s [ab y ω x ω ab] y ω x ψ x ω y ψ [ρ                          ][ )( 2 2 2 2 y t x t α y t x ψ x t y ψ                x t gβρ yx ψ 2 y ψ x ψ abs o 22 4 4 4 4 4 g             ][ `` 2 2 2 2 2 3 3 2 3 1 ))((1 x ψ y ψ b x ψ yx ψ s             , 2 2 2 2 2 2 3 3 3 2 ))((1 x ψ y ψ b xy ψ y ψ s             , & 2 2 2 3 3 )(1 yx ψ b yx ψ s       now, the mathematical problem formulated above was placed in dimensionless form by defining the new dimensionless variables [5]: l y y , l x x **  k ql tt tt tt θ c ch c              b.c.2for b.c.1for α ωl ω , α ψ ψ ** 2  (10) (11) (12) (13) (14) (15) (16) (8) (9) (6) (7) this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. ala′a abbas muhadi /al-khwarizmi engineering journal ,vol.3, no.1, pp 63-80 (2007) ٦٧ inserting all the dimensionless variables into eqs.(12) to (16), yield the following final non – dimensional equations: * ** ω y ψ x ψ       2* 2 2* 2 * g* * 3 * * 2 * * 1* 2* *2 2* *2 * * * * * * * * * s x s 4 y s x s pr y ω x ω pr y ω x ψ x ω y ψ                          ][ ][ 2 2 2 2 **** * ** * y θ x θ y θ x ψ x θ y ψ                where; * * 2*2* *4 4* *4 4* *4 ** g x θ rapr yx ψ 2 y ψ x ψ prs             ][ 2 2 2 2 2 3 3 2 3 1 ))((1 * * * * * * ** * * x ψ y ψ ne x ψ yx ψ s             2 2 2 2 2 2 3 3 3 2 ))((1 * * * * ** * * * * x ψ y ψ ne xy ψ y ψ s             2 2 2 3 3 ))((1 ** * ** * * yx ψ ne yx ψ s       αρ ab pr o * is the modified prandtl number.              b.c.2for number rayleighmodifiedtheis b.c.1for number rayleighmodifiedtheis )( αkab βlρ nurara abα ttβlρ ra ra 4 o e * e ch 3 o e qg g 2l bα ne  is the nondimensional parameter of prandtl – eyring model. the physical quantities of interest in this problem are the local nusselt number along the heated wall [6], defined by: )( ch ttk ql nu   and also the average nusselt number, which is defined as: -:case (i) dc y θ x θ nu * * y 1 or y x **a 22 118.1 0 22 * )()(         where 22 )()( rr dydxdc  -:case (ii) dx θ nu *yh a 0 1 0 1   3. numerical method : numerical methods have been developed to handle problems involving nonlinearities in the describing equations, or complex geometries involving complicated boundary conditions. a non-uniform finitedifference technique is applied to solve the governing equations. these three equations (eqs.(17), (18), and (19)) are to be solved in a given region subject to the condition that the values of the stream function, temperature, and the vorticity, or their derivatives, are prescribed on the boundary of the domain. the finite difference approximation of the governing equations was based on dividing the ( 10 *  x ) interval into (m) equal (17) (18) (19) (20) (21) (22) (23) (24) (25) (26) this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. ala′a abbas muhadi /al-khwarizmi engineering journal ,vol.3, no.1, pp 63-80 (2007) ٦٨ segments separated by (m+1) nodes. likewise, the ( *y ) interval was divided into (n) segments, regular and irregular meshes are result as shown in figs.(3 & 4). regular mesh has been covered most the triangular region except for the region near from the inclined wall, which was covered with irregular mesh. assume that unknown variable f(x,y) possesses continuous derivatives, so the approximation of second derivative of (f) to determine interior point are [2]: )x50 ff)1( ) x ( 22 j,1-iji,j,1i ,2 2 r ji xa. aaff δ(δ       and the first derivative central difference are: r jijiji ji xax fafaf x f δδ 2 ,1 2 , 2 ,1 , )1( )(       where, (a) and (b) are factors representing the degree of non – uniformity and the values of these factors equal to (1) for regular mesh, and calculated from equation of line for irregular mesh. and; 1b 1a   yby xax r r δδ δδ 1b 1a   b y y a x x r r δ δ δ δ the usual procedure for obtaining the form of partial differential equation with non uniform finite-difference method [7] is to approximate all the partial derivatives in the equation by means of their taylor series expansions. eq.(17) can be approximated using central – difference at the representative interior point (i,j), thus, eq.(17) can be written for regular mesh as: ]xa x)b(yby)a/[(]ωyb yxax.xaxbψ ψybyaψψ[ψ r r * ji,r rr * -ji, * ji,r * j,-i * j,i * ji, )δ (δ)δ(δ)δ )(δδ(δ)δ)(δ ()δ)(δ( 2 2222 22222 1 1 22 11 11 50      also, a central – difference formulation can be used for eqs.(18), and (19). but this problem will need to be solved for reasonably high values of modified rayleigh numbers; it is known that such a formulation may not be satisfactory owing to the loss of diagonal dominance in the sets of difference equations, with resulting difficulties in convergence when using an iterative procedure. a forward – backward technique can be introduced to maintain the diagonal dominance coefficient of (ωi,j) in eq.(18) and (θi,j) in eq.(19) which determines the main diagonal elements of the resulting linear system; this technique is outlined as follows [8]: set; * 1 22 1 )1( j,-i * ji, * j,i ψaψaψγ   and * 1 22* 1 )1( -ji, * ji,ji, ψbψbψβ   then approximate eq.(18) by: 0 4 250 50 1150 22 22 321 2222 11 22 11 22 2222                       )] x ω yby β y ω xax γ (s) x s y s x s (pr[ )yby)(xax(.))ωbω( )xax()ωaω)(yby((pr. ω))xax)(b()yby)(a((. * * r * * r * g* * * * * * * rr * -ji, * ji, r * j,-i * j,ir * * ji,rr δδ δδ δδδδ δδδδ δδδδ and eq.(19) by: if if (27) (28) this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. ala′a abbas muhadi /al-khwarizmi engineering journal ,vol.3, no.1, pp 63-80 (2007) ٦٩ 0 250 50 1150 2222 2222 11 22 11 22 2222              ] x θ yby β y θ xax γ [ )yby)(xax(.bθθ )xax(aθθ)yby((. θ))xax)(b()yby)(a((. * r * r rrji,ji, rj,ij,ir ji,rr δδδδ δδδδ))( δδ)(δδ δδδδ now, if )0),1(,0 21 1        b b y ff y f ,γ ji,ji, (and δ )1),0(,0 21 1        b b y ff y f ,γ r ji,ji, (and δ )0),1(0 21 1        a a , x ff x f ,β r j,iji, (and δ )1),0(,0 21 1        a a x ff x f ,β ji,j,i (and δ to assure the diagonal dominance of the coefficient matrix for )ji, * ji, θω (and)( , which depends on the sign of ( γ ) and (β) , eqs.(18) and (19) are expressed in the following difference forms: )] )())(( )())(( ())(( 25.0)))(1())(1((5.0/[ )])((25.0 ) )()( 4 )))()( ( ))((25.0))( 5.0 )( ))(( 25.0( ))(5.0 )( ))(( 25.0())(5.0 )( ))(( 25.0())( 5.0 )( ))(( 25.0[( 21 21 21 12 21 21 21 12 2 2 2222 2222 2222 )3)3)2)2)1)1 222222 2 2222 2 22 2 2222 2 22 2 2222 1 22 2 2222 1 aa rr b r b r rr rr rr * jg)i, aa r * j,ai * j,ai b r b * b-ji, * bji, aa r * j,ai * j,ai rr ** 1-ji,r * rr rr * j1,ir * r rr * j1,-ir * rr rr* 1ji,r * r rr* ji, xxyby β yyxax γ ybyxax xaxbybya ybyxaxs xx ss y(y( ss xx ss ybyxaxprωxax prb yxax ybyxax γb ωybypr xyby ybyxax βaωybypra xyby ybyxax βaωxax pr yxax ybyxax γbω δδδδ δδδδ δδδδ δδδδ δδδδ δδδδδδ δδδδδδ δδδ δδδδ δδ δδδ δδδδ δδ δδδ δδδδ δδ δδδ δδδδ                               )] )())(( )())(( ( ))((25.0))( )1())(1((5.0/[])) (5.0 )( ))(( 25.0( ))(5.0 )( ))(( 25.0())(5.0 )( ))(( 25.0()) (5.0 )( ))(( 25.0[( 21 21 2 2 222222 22 1 2 2 2 2222 2 ,1 22 2 2222 2,1 22 2 2222 11 2 2 2 2222 1 aa rr b r b r rrr r-ji,r rr rr jir r rr j-ir rr rr ji,r r rr ji, xxyby β yyxax γ ybyxaxxax bybyaθxa xb yxax ybyxax γb θyby xyby ybyxax βaθybya xyby ybyxax βaθxa x yxax ybyxax γbθ δδδδ δδδδ δδδδδδ δδδ δ δδδ δδδδ δδ δδδ δδδδ δδ δδδ δδδδ δ δ δδδ δδδδ                       an under – relaxation technique can be applied to accelerate the convergence of eq.(30); the expression is used in this technique presented in the following : )()()( computedωfvωfvω * ji, k* ji, k* ji,  11 where (fv) is the relaxation factor for the vorticity. the value of this relaxation factor is in the range of (0 to 2) [2]. in order to obtain results of the conservation equations, the above equations (eqs.(27), (30), and (31)) are subjected to the following boundary conditions [9]: case (i) : 0 x 1x0.5 )x-2(1y x 0.5x0 2xy y y 0y x * ** ** ** *                      0 10 00 10 * * * * * * * * * * (29) (30) (31) this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. ala′a abbas muhadi /al-khwarizmi engineering journal ,vol.3, no.1, pp 63-80 (2007) ٧٠ :case (ii) x 1x0.5 )x-2(1y x 0.5x0 2xy 01 y y 0y x * ** ** * * 00 00 0 10 * * * * * * * * * * *                      also, the following finite difference equation for the vorticity at a wall is adopted as the boundary condition for the vorticity equation (see fig. (2)): for inclined wall ) y ψψ x ψψ (2ω 2 r 2 2 r 1 δδ     oo o for lower wall 2 ω x ψψ3 ω 1 2 1    δ )( o o the numerical work starts with giving the distributions of stream function and temperature for natural convection as the zeroth-order approximation. then, obtain the zeroth-order approximation of vorticity: no flow and pure conduction. based on these old fields, equation (٢٧) is used to determine point-by-point the new ( * ) field, and equation (٣٠) is used to determine the new ( * ), while the energy equation (31) is used to determine the new (θ ) field. the iteration process is terminated under the following condition: 5 , , 1 , ,, 1 10   ji ji r ji ji r ji r  where, ( ) stands for either (  or,, ** ); (r) denotes the iteration step. before starting the computational solution, the grid independence of the results must be tested. thus, numerical experiments have been carried out to solve a two – dimensional convection problem in which the non – dimensional parameter (ne = 0). the modified prandtl number in this test is set to be (6.7), while the grid size varies from (10×10) to (60×60) for different values of modified rayleigh number as shown in fig.(5). it is found that the change in the nusselt number for grid size of (35×35) and (45×45) is less than (0.9) percent for the range of modified rayleigh number ( 53 1010  era ). therefore, the number of grid that is adopted in the present study is (35×35) for all four cases. the number of grid was selected as a compromise between accuracy and speed of computation. 4. results and discussion :case (i) :triangular enclosure under b.c.1 a-temperature and flow fields: the contour lines of the temperature distribution and flow fields for different values of system parameters are presented in figs.(6) to (9). for conduction regime (i.e. at era < 103 and ne < 1), the isotherms are almost straight lines. however, the buoyancy induced flow at era ≥ 103 or ne ≥ 1 changes the direction of the isotherms, and, as a result, clockwise convective motion is formed, as shown in figs.(6 & 8). it is observed that as the era or ne increases more, isotherms shift towards the hot wall, see fig.(7). the shift is (32) this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. ala′a abbas muhadi /al-khwarizmi engineering journal ,vol.3, no.1, pp 63-80 (2007) ٧١ more pronounced as the era increase more and more, as shown in fig.(9). this results in the asymmetry of the temperature field in the core. it can also be seen that as era or ne increases, the change in temperature with respect to height, reduces in the lower portion of the enclosure, but increases faster in the upper portion. furthermore, the temperature gradient near the hot wall increases rapidly as the era increases. the behavior is just the reverse near the cold wall. for a given pr* and ne, an increase in era results in a thicker cold layer near the bottom wall and a high temperature field near the top edge (figs.(7a & 9a). the growth of the boundary layers on the inclined walls are also observed to be affected by a variation in era , pr* and ne. the increase in ne at a fixed era is seen to increase the rate of boundary layer growth on the hot wall. this behavior is reversed on the cold wall. the net result is a shift of the core toward the cold wall and toward the top edge of the heated wall. this shift is further strengthened if there is an increase in era or ne. generally higher convective velocities in the lower left – hand corner are produced as a result of the shift. also, the horizontal velocity in the upper region is much higher as compared to that in the lower region for increased values of era or ne. fig.(10) represents the variation of ψmax with era for different values of ne and pr*=10. it is seen that the value of ψmax increases and reaches the peak value at era = 105, for ne.=10. fig.(8a) shows the streamlines at era =105, pr* = 1 and ne =0. the flow consists of one large cell rotating in the enclosure. it also shows the flow slowly rises along the heated wall, turning the edge at the top of the enclosure, and slowly slides along the cooled wall. b-heat transfer coefficient: to understand the heat transfer process by natural convection, it must be to evaluate the heat transfer coefficient (h), but to make the present work having generality, the calculated results must be in dimensionless form. therefore, it must be needed to evaluate nusselt number (nu) as a function of influence parameters. fig.(11) shows the variation of anu versus era with different values of ne and pr*=10 on the hot wall of the enclosure. it is clear that anu equal to (3.253) in the conduction regime. this is mainly due to the very small distance between the isothermal walls in the upper region of the triangular enclosure, which allow more heat flow rate to transfer along it. also, the depth of the layer is thin and the slope of the inclined wall is large. it is also seen that for range of modified rayleigh number before (103), the rate of increase in anu against rae for different values of ne and a fixed pr* is relatively small. but, anu increases rapidly as ne increases for rae0≥ 103 expressing the increase of convective heat transfer. it is also noticed that this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. ala′a abbas muhadi /al-khwarizmi engineering journal ,vol.3, no.1, pp 63-80 (2007) ٧٢ the effect of ne on anu is more pronounced as the rae numbers increase. case (ii) :triangular enclosure under b.c.2 a-temperature and flow fields: figs.(12) to (17) show the contour lines of the temperature distribution and flow fields for the present case. for low * era , the isotherms in the lower region are almost parallel for a large part of the inclined wall indicating that a substantial amount of energy is rejected on this part when the * era is small. however, the heat transfer on this surface decreases with an increase in * era which clearly implies that the effect of the lower portion boundary condition diminishes with higher velocities or higher * era , as shown in figs.(13 & 15). as the * era or ne increases, the temperature in the lower portion of the enclosure decreases while that in the upper region increases. the stratification in the upper layers is, thus, more strength than that occurs in case (i) as show in figs.(9d) and (17d), this because of the change in the boundary condition at enclosure walls from (b.c.1) to (b.c.2), which allow less heat flow rate to transfer along the lower part of isothermal wall. as * era increase more, or ne increase for high values of * era , results in the stable of the stratification area near the top edge and decreased θmax respectively. in fig.(15d), the isotherms become parallel for large part of inclined wall in the upper region indicating that a large amount of energy is rejected along it. as * era increase more and more, or ne increase for high values of * era the temperature and flow field modified, and the stratification layer concentrated in the small region near the top edge of the enclosure, as presented in fig.(17d). the natural of the convection cell, initially (i.e. at * era = 10) the flow consists of a single cell filling the entire enclosure and rotating slowly in the clockwise direction. however, an increase in * era or ne results in changing the flow pattern from unicellular to multicellular flow. fig.(16d) shows the streamlines at * era = 105, ne = 1, and pr* = 10. this flow exhibits two counter – rotating cells, each covering half of the enclosure. both components have the same maximum magnitude (ψmax = 14.2), but are of opposite sign indicating an opposite direction of flow. these two cells are symmetric about the center line of the enclosure. the convective velocity near the wall is lower than that along the line of symmetry. fig.(18) represents the variation of ψmax with * era for different values of ne and pr*=10. furthermore, the isotherms are symmetric about the vertical line at x.=.0.5, and the maximum temperature always occurs at the middle of the lower wall, and is a function of * era , ne, and pr*. b-heat transfer coefficient: the average nusselt number as defined by eq.(26) is presented in fig.(19). it is seen that for * era and ne are less than this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. ala′a abbas muhadi /al-khwarizmi engineering journal ,vol.3, no.1, pp 63-80 (2007) ٧٣ (104) and (1) respectively, the rate of increase in anu is relatively small. then, anu increases rapidly as * era or ne increases expressing the existence and increase of convective heat transfer. as already indicated by the temperature field, the average nusselt number for the present case is higher than that for the case (i) for the same given condition. finally, four correlation equations have been predicted depending on variation of modified rayleigh number, modified prandtl number, and non – dimensional parameter of the prandtl – eyring model for both two cases, by using least square method. case (i): triangular enclosure under b.c.1 8891.0,10 ,672.1 47.10237.00962.0   r .ne neprranu * ea 0 1)( and, 9621.0,10 ,512.1 0205.0067101190   r ne. neprranu .*. ea 10 1)( case (ii): triangular enclosure under b.c.2 874.0,10 ,855.2 036.10098.00901.0*   r .ne neprranu * ea 0 1)( and, 9592.0,10 ,677.1 0699.0089901490*   r ne. neprranu .*. ea 10 1)( the above correlations are acceptable in the range of modified rayleigh number (102 to 105), modified prandtl number (1 to 100), and non – dimensional parameter ( ne= 0 to 10 ). to ensure that these approximation correlations are usable, the coefficient of determination (r) had been obtained for each equation. the minimum value of (r) was (0.874), that means these approximate equations are good for predicting the value of average nusselt number. figs.(20) and (21) show the comparison between numerical and predicted results. agreement between numerical and predicted is close, although most the predicted points lie near the theoretical line. ٥. conclusions : the main conclusions of the present work are: 1for the two cases that have been solved, it has been demonstrated that the average nusselt number is a strong function of modified rayleigh number, non – dimensional parameter (ne), and modified prandtl number, also the results show the average nusselt number: aincreases as (ra) increases, for a given values of (ne) and (pr*). bincreases as (ne) increases except for (ne > 0.1) at (ra ≥105), for a given value of (pr*). canu for the second case of thermal boundary conditions (b.c.2) is always higher than for the first case (b.c.1). 2for large modified rayleigh number, the non – dimensional parameter (ne) of the prandtl – eyring model has, for a given modified rayleigh and prandtl numbers, a large effect on the heat transfer rate, while for small (ra), it does not have much effect on (33) (34) (35) (36) this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. ala′a abbas muhadi /al-khwarizmi engineering journal ,vol.3, no.1, pp 63-80 (2007) ٧٤ the heat transfer because in this situation, the convection is very weak and the dominant mode of energy transfer is conduction. 3in the first case of the boundary conditions (b.c.1), the flow is mainly single cell flow, while in the second case (b.c.2), the flow consist of two counter-rotating cells, each covering half of the enclosure. :references [1] elba, o. b., julio, c. r., and obidio, r., “numerical simulation for the natural convection flow”, numerical methods in fluids, vol. 30, pp. 237-254, 2000. [2] nabeel, m., “a numerical study of natural convection heat transfer in an enclosure for newtonian and non newtonian fluids”, m. sc. thesis, university of kufa , 2005. [3] miomir, r., “numerical investigation of laminar natural convection in inclined square enclosures”, physics, chemistry and technology, vol. 2, pp.149-157, 2001. [4] j. m. coulson, and j. s. richardson, "chemical engineering", bergamon, international library, vol..3, 1983. [5] myers, e., “analytical methods in conduction heat transfer”, mc graw – hill book company, inc., 1971. [6] frank, k., and mark, s., “principles of heat transfer”, 5th edition, pws publishing company, 1997. [7] bejan, a., “convection heat transfer”, wiley, inter science publication, john wiley and sons, inc., 1984. [8].najdat n., “laminar flow separation in constructed channel”, ph.d. thesis, michigan state university, 1987. [9] g., lauriat, “numerical study of the interaction of natural convection with radiation in nongray gases in a narrow vertical cavity”, int. journal of heat transfer, vol. 2, pp. 153-158, 1982. fig.(1) physical model and coordinate system. (a) case (i); (b) case (ii) th g tc x y 0   y t l (a) tctc g y t kq    l (b) this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. ala′a abbas muhadi /al-khwarizmi engineering journal ,vol.3, no.1, pp 63-80 (2007) ٧٥ fig.(2) nodes used to obtain vorticity at the inclined wall. fig.(3) regular mesh . fig.(4) irregular mesh. fig.(5) variation of nusselt number with the number of grid points for different modified rayleigh number. case (i) . (a) (b) (c) (d) fig.(6) pattern of streamlines for rae =103 and pr*=10. (a) ne=0, (b) ne=0.1, (c) ne=1, (d) ne=10. case (i) 0 2 1 (i,j) (i,j–1) (i+1,j) (i,j+1) (i–1,j) δx δy δyr δx(i,j) (i,j–1) (i+1,j) (i,j+1) (i–1,j) δxr δy anu number of grid 0 1 2 3 4 5 6 0 20 40 60 80 ra*=1000 ra*=10000 ra*=100000 this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. ala′a abbas muhadi /al-khwarizmi engineering journal ,vol.3, no.1, pp 63-80 (2007) ٧٦ (a) (b) (c) (d) fig.(7) pattern of isotherms for rae =103 and pr*=10. (a) ne=0, (b) ne=0.1, (c) ne=1, (d) ne=10. case (i) (a) (b) (c) (d) fig.(8) pattern of streamlines for rae =105 and pr*=1. (a)ne=0, (b)ne=0.005, (c)ne=0.05, (d)ne=0.1. case (i) (a) (b) (c) (d) fig.(9) pattern of isotherms for rae =105 and pr*=1. (a)ne=0, (b)ne=0.005, (c)ne=0.05, (d)ne=0.1. case (i) ψmax rae fig.(10) variation of max)( with the rae for different values of ne and pr*=10. case (i) 0 5 10 15 20 25 30 100 1000 10000 100000 ne=0 ne=0.1 ne=1 ne=10 this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. ala′a abbas muhadi /al-khwarizmi engineering journal ,vol.3, no.1, pp 63-80 (2007) ٧٧ (a) (b) (c) (d) fig.(12) pattern of streamlines for ra* e =104 and pr*=10. (a) ne=0, (b) ne=1, (c) ne=6, (d) ne=10. case (ii) (a) (b) (c) (d) fig.(13) pattern of isotherms for ra* e =104 and pr*=10. (a) ne=0, (b) ne=1, (c) ne=6, (d) ne=10. case (ii) (a) (b) (c) (d) fig.(14) pattern of streamlines for ra* e =105 and pr*=1. (a) ne=0, (b) ne=0.1, (c) ne=0.5, (d) ne=1. case (ii) (a) (b) 0 1 2 3 4 5 6 7 8 100 1000 10000 100000 ne=0 ne=0.1 ne=1 ne=10 rae nua fig.(11) variation of anu with the rae for different values of ne and pr*=10. case(i) this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. ala′a abbas muhadi /al-khwarizmi engineering journal ,vol.3, no.1, pp 63-80 (2007) ٧٨ (c) (d) fig.(15) pattern of isotherms for ra* e =105 and pr*=1. (a) ne=0, (b) ne=0.1, (c) ne=0.5, (d) ne=1. case (ii) (a) (b) (c) (d) fig.(16) pattern of streamlines for ra* e =105 and pr*=10.(a)ne=0,(b)ne=0.1,(c)ne=0.5,(d)ne=1.case(ii) (a) (b) (c) (d) fig.(17) pattern of isotherms for ra* e =105 and pr*=10. (a) ne=0, (b) ne=0.1, (c) ne=0.5, (d) ne=1. case (ii) 0 2 4 6 8 10 12 14 16 1000 10000 100000 ne=0 ne=0.1 ne=1 ne=10 max)( * era fig.(18) variation of max)( with the * er for different values of ne and pr*=10. case(ii) 0 2 4 6 8 10 12 14 16 1000 10000 100000 ne=0 ne=0.1 ne=1 ne=10 anu * era fig.(19) variation of nua with the * er for different values of ne and pr*=10. case(ii) this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. ala′a abbas muhadi /al-khwarizmi engineering journal ,vol.3, no.1, pp 63-80 (2007) ٧٩ 0 5 10 15 20 0 5 10 15 20 متسلسلة1 متسلسلة2 pr ed ic te d re su lt s (n u) numerical results (nu) fig.(20)0numerical results vs. predicted results of correlation equation. case (i) 100 .ne  ne1.0 0 5 10 15 20 0 5 10 15 20 متسلسلة1 متسلسلة2 p re di ct ed r es ul ts ( n u) numerical results (nu) fig.(21)0numerical results vs. predicted results of correlation equation. case (ii) 100 .ne  ne1.0 this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. ala′a abbas muhadi /al-khwarizmi engineering journal ,vol.3, no.1, pp 63-80 (2007) ٨٠ ة بالحمل الطبیعي الطباقي لموائع نیوتونیة وغیر نیوتونیة في وسط مغلق مثلث الشكلانتقال الحرار عالء عباس مھدي .د جامعة الكوفة –كلیة الھندسة قسم الھندسة المیكانیكیة : الخالصـــــــــــة ي , في ھذا البحث ل الطبیع رارة بالحم ال الح ة النتق ة عددی راء دراس م إج اقي ت ة لا الطب ع نیوتونی د لموائ ائي البع تقر ثن ر مس –وغی 102( كل ضمن مدى واسع لعدد رالي المحورالش مثلثفي وسط مغلق نیوتونیة ≤ ra ي ) 105 ≥ ل الریاض دي للمودی وللمقدار الال بع )prandtl – eyring ( یمتد من)0.≤.ne≤ 10 (أخذ في المدى ولعدد برانتل المحور)pr* =1,10, and 100 .(نوعان من افترض دما , الثاني. ات حرارة مختلفة ومنتظمة والجدار السفلي معزولمسخنة إلى درج المائلةعندما تكون الجدران , األول. الظروف الحدیة عن دران ة یكون الجدار السفلي مسخن بمصدر حراري ثابت بینما الج ة المائل ة وثابت رارة منخفض ة ح د درج لوك . عن أن س رض ب ذلك افت ك – prandtl(یخضع للمودیل الریاضي نیوتونیة –الموائع غیر eyring .( تم تمثیل نتائج الدراسة بداللة خطوط درجات الحرارة الثابتة عالقة معدل عدد نسلت مع باإلضافة إلى رسومات بیانیة أخرى تمثل. وخطوط االنسیاب لبیان سلوك درجة الحرارة والجریان في الحیز دي إن. المذكورة أعاله المتغیرات رارة ) ne(الدراسة الحالیة بینت تأثیر المقدار الال بع ة الح رعة ودرج ى الس دد . عل ت إن ع ذلك بین ك ة . والظروف الحدیة) ne(بعدي .والمقدار الال حوروعدد برانتل الم ھو دالة قویة من عدد رالي المحور نسلت ات تقریبی اد عالق م إیج ت ne).(والمقدار الال بعدي على عدد رالي المحور وعلى عدد برانتل المحور عدل عدد نسلتم ةتمثل اعتما دی this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ <4d6963726f736f667420576f7264202d20d4e5cf20e6e3c7e5d120e6c7cde3cf20d2edcfc7e432322d203333> al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 16, no. 3, sptember, (2020) p. p. 2233 arduino-based controller for sequence development of automated manufacturing system shahad sarmad khaleel* maher yahya salloom** ahmed m. shammari*** *, ***department of automated manufacturing engineering/ al-khwarizmi college of engineering / university of baghdad ** department of mechatronics engineering/ al-khwarizmi college/ of engineering/ university of baghdad *email: shahadsarmad36@gmail.com **email: drmahir@kecbu.uobaghdad.edu.iq ***email: ahmadhzaam@yahoo.com (received 6 february 2020; accepted 5 july 2020) https://doi.org/10.22153/kej.2020.07.001 abstract it has become necessary to change from a traditional system to an automated system in production processes, because it has high advantages. the most important of them is improving and increasing production. but there is still a need to improve and develop the work of these systems. the objective of this work is to study time reduction by combining multiple sequences of operations into one process. to carry out this work, the pneumatic system is designed to decrease\ increase the time of the sequence that performs a pick and place process through optimizing the sequences based on the obstacle dimensions. three axes are represented using pneumatic cylinders that move according to the sequence used. the system is implemented and controlled to carry an object from one position to another. the movement of the system is controlled using three linear potentiometers, which are connected to an analog input of the microcontroller to feed the value of the pneumatic rod distance. to achieve the best path of the product moving, it is necessary to compare among several sequences. . the results show the sequences that compared with the reference under fixed speed, such as sequence that has been developed by combining two axes, and then the system path time has been reduced in taking the product from one place to another. therefore, some factories need to reduce the sequences and thus reduce the time to transfer the product. keywords: automation, pneumatic system, automated pick and place, sequence optimization. 1. introduction factories need continuous improvement to keep pace with rapid development and maintain the success of the factory and its products; one of the most important sections that the final product depends on it is the handling machine. different activities such as handling, sorting, moving can be done using handling machines where compressed air is suitable to do these jobs. the scale of factory success depends on the required time to complete product manufacturing. so, automated manufacturing has been used to reduce the time needed. using material handling machines has a good impact on reducing the time to handle, transport, or separate products. also, dropping down more than 80% of the time spent in waiting or transport of the material on the shop floor, which leads to reduce wastage, breakage, and loss of material [1]. in 2005, a novel altered heartbeat width regulation (mpwm) valve beating calculation introduced to permit on/off solenoid valves that can be utilized instead of expensive servo valves. a control execution correlation between the framework reaction of the standard pwm strategy and that of the altered pwm method demonstrated a critical presentation increment. a shahad sarmad khaleel al-khwarizmi engineering journal, vol. 16, no. 3, p.p. 2233 (2020) 23 state-criticism controller with position, speed and quickening input was effectively actualized as a nonstop controller. an exchanging calculation for control boundaries utilizing a learning vector quantization neural network (lvqnn) has recently proposed, which arranges the outside heap of the pneumatic actuator. the adequacy of this proposed control calculation with smooth exchanging control has been exhibited through investigations with different outer loads [2]. one part of a mechanized framework. a gripper can be connected to a robot or it tends to be a piece of a fixed mechanization system, described guidelines for the design of grippers for use in modular manufacturing work cells. guidelines have been applied to a wide variety of grippers [3]. many tools contribute in development of automated manufacturing such in 2006, a novel single-camera vision framework to quantify part and board arrangement in pick and place machines. this framework is a piece of a creative idea for a quicker pick and place machine idea. a current two-camera vision framework is contrasted and the single-camera framework. additionally, the mistake spending which impacts the last estimation precision is hypothetically examined for the novel single-camera vision framework [4]. in 2010, the structure of a computerized pick and spot framework was introduced. the fragmented parts are gathered from underneath. the segment ought to be gotten a handle on, raised it at the highest point of the stock, and moved into the weight machine. it needs to descend a little in the press machine to put the segment on the bite the dust shoe. since these two tasks are comparable, the framework can be organized utilizing two arms situated symmetrical to one another. the main situation of the essential arm is meeting, the halfdone item, along these lines, it in a withdrawn position. the subsequent arm meets the weight machine, just as withdrawn. the two arms are hung on a third arm that returns vertically. the body of the three arms is put on a turning actuator. the framework can be planned for high adaptability as far as the quantity of different grippers that can be utilized. robotic/finger grippers can be utilized on non-attractive segments. this can be, practiced by utilizing pneumatic chambers of abbreviated stroke [5]. in 2013, built up an independent picking robot system for plantation developed tomatoes, which comprises of four significant parts: the end effectors, machine vision, robot bearer, and control system. accomplished fruitful paces of coordinated picking. thus, a self-governing picking robot system was effectively evolved and it should be additionally tried for genuine tomato picking tasks in plantations later on [6]. pneumatic grippers are easy to utilize and are by and large financially savvy in light of the fact that pneumatic hardware's are anything but difficult to keep up. the handling of abstract materials and mechanisms to pick and place is widely found in factory automation and industrial manufacturing. in 2013, a two jaw drove gripper was planned that is not the same as the typical cam and sequent gripper through the controlled movement of the jaws which had done utilizing of pneumatic cylinders worked compressed air [7]. in 2015, the design and study of intelligent electric arc furnace applications system using a proportional directional control valve have been introduced. the tests showed that the electrohydraulic closed loop system for position was good and the output was good and acceptable [8]. in 2016, it has been structured and manufactured a pneumatic arm for pick and spot of round and hollow articles. the treatment of materials and instrument to pick and spot objects was from lower planes to higher planes. the planned pneumatic arm comprised of two chambers; a pole works with lead screw system fit for changing over movement of cylinder to rotational movement of arm with assistance of utilizing packed air. the planned procedures were completed dependent on coordinated data of kinematics elements and auxiliary investigation of the ideal robot arrangement. the profoundly powerful pneumatic arm model could be effortlessly set at middle of the road positions by controlling the weight utilizing the stream control valve. it could be utilized in stacking and emptying of products in a transportation harbor as the development of merchandise is done from lower plane to higher plane [9]. in 2016, pickplace system is an application that is extremely used in manufacturing. this pick -place activity is done all over the place and whenever in light of the fact that a great deal of human development includes picking and placing objects. pick -place robot could be characterized as a basic robot. the fundamental capacity was to move things starting with one spot then onto the next. a strong gripper has been intended to perform simpler and quicker picking and putting tasks for different shapes and sizes objects [10]. shahad sarmad khaleel al-khwarizmi engineering journal, vol. 16, no. 3, p.p. 2233 (2020) 24 the gripper improved the picking and setting activity in the assembling field to deliver more outputs without the requirements to reprogram every once to sense the object size. by the inciting vitality, gripper frameworks can be pneumatic, pressure driven, vacuum-based, servo-electric, attractive, and so forth. determination of a specific sort of engine relies upon a large number of variables including the heaviness of the held onto object, the necessary speed for its grasping, the forced clipping power, the consistence of the whole framework, and so on. pneumatic activation is one of the most every now and again experienced driving modalities of gripper frameworks, because of its points of interest. these incorporate the straightforwardness of the control graphs, the chance of securely overburdening the framework, simple support, the nondirtying working medium, consistence, and so forth. another useful arrangement of a gripper framework impelled by a pneumatic muscle [11]. one of the major and most performed work is picking and putting of occupations from source to goal. these days, the business is progressively turning towards pc based robotization, chiefly because of the requirement for expanded efficiency and conveyance of final results with uniform quality. in 2017, pick and spot robot was intended to deal with an alternate shape and size and furthermore unpredictable items, the pick and spot robot can play out the pick and spot the sporadic parts on 260o inside the workspace [12]. in 2017, the plan and execution of pick and spot robot control framework on an equipment stage dependent on programmable rationale controllers (plc) have been showed up, which interfaces with the detecting and incitation gadgets for robot control. the framework incorporates a pick and spot robot whereby a dream framework is coordinated with its workspace to distinguish work pieces concerning their shape and shading. subsequent to detecting and perceiving the items highlights, matlab sends results to plc. plc sends related requests to the robot's joints, which are made of dc and stepper engines. the robot picks the item, finds it in its particular goal, and turns around to its reference area. the presentation of the created robot was confirmed through trial results [13]. the automatic production line can perform feeding, transportation, and sorting functions. in 2019, two scada/hmi systems were implemented using two different software. tia portal software is used to build hmi, alarm, and trends in touch panel, which is helped an operator to control and monitor the production line. labview software is used to create hmi and patterns on the computer screen. it is linked with microsoft excel (me) to generate an information table that helped to monitor the performance of the pneumatic equipment. the communication between master program tia portal v15 software and slave program labview is through ole process control (opc) service. opc offers greater flexibility and lower cost of development, integration, and assembly for controlling and monitoring the industrial process. moreover, the opc can involve a wide variety of data resources, as in [14]. the most important of automated systems is that how to improve and increase production. but there is still need more efforts to improve and develop the work of these systems. the objective of this work is to study time reduction by combining multiple sequences of operations into one process. in this work, a 3d-model of a pneumatic pick and place system is proposed. this approach uses several sequences of movements to get the best way of direction to pick an object from one position to another position with high accuracy. 2. basics of control system the key constituents for any automatic process are: (1) power source, (2) input control component, and (3) programmable order structure, as appeared in figure.1. fig.1. the fundamental constituents of any automated process [15]. shahad sarmad khaleel al-khwarizmi engineering journal, vol. 16, no. 3, p.p. 2233 (2020) 25 3. control loop of proposed system the control loop for the system shown in figure 2 describes how the system works according to sensors. the controller gives feedback to the arduino, which orders the directional control valve to take action by moving the cylinders. fig. 2. the mechanism of work of the proposed system. 4. design of the proposed system initially, the mechanical part is designed by solid works program, as shown in figure 3, where three axes x, y, and z are designed, as basis of their movement. fig. 3. 3d-module of the assembly parts. fig.4: layout of 3-axis pneumatic pick and place system. after the mechanical part is designed through the solid works program, a motion simulation is created to verify the axes for design implementation. five linear actuators, called pneumatic cylinder type double acting that makes up the system and layout in 3-axis, as shown in figures (3 & 4), one cylinder for the x-axis, two cylinders for the y-axis, and also two cylinders for the z-axis. each cylinder requires two directional control valves type five-way/twoposition single solenoid return spring, one of which is responsible for extending and the other responsible for retracting. the x-axis cylinder moves from one side to the other and vice versa and the y-axis cylinder moves up and down, and the z-axis cylinder whose movement is moving towards the piece and returns in the other direction. a vacuum gripper is installed at the end of the z-axis cylinder to grip and release the piece, which is its working principle venturi pipe, as shown in figure 5 fig. 5. electro-pneumatic circuit of the vacuum gripper shahad sarmad khaleel al-khwarizmi engineering journal, vol. 16, no. 3, p.p. 2233 (2020) 26 in order to be sensitive to the movement of these cylinders, it is necessary to add a sensor to the distance covered by the cylinder, this sensor called linear potentiometer. the final form of mechanical design, assembly, and air and electronic connection are shown in figure 6: (a, b). a b fig. 6. a) final mechanical design of pneumatic pick and place system, b) components of the system. all the measurements were taken by setting axis (0,0,0) as the reference point and are set to be zero position. all directions are chosen to be positive with respect to the axis (0,0,0). the fundamental dimensions are tabulated in table1. table1, the limitations of mechanical dimensions setup. parameter dimension in mm max. x-axis 100 max. y-axis 100 max. z-axis 100 min. x, y, and z-axes 0 gripper diameter 40 piece diameter 50 cylinder outer diameter 20 cylinder inner diameter 10 stroke for all cylinders 100 5. controlling the system microcontroller (arduino uno), gives an open-source and simple to using programming devices, for composing codes and transferring it to the board. it is regularly alluded to as the arduino integrated development environment (ide). arduino uno is used for controlling the pneumatic system, through the entering signal from the linear potentiometer. it processes and directs to a current amplifier (relay board) to send a signal to the valves as an output signal, as shown in figure 7. fig. 7. control wiring. each valve needs a higher current as it works as a switch when the signal reaches it. as a result, the compressed air for the movement of the cylinder has controlled this responsibility, as illustrated in figure 8. shahad sarmad khaleel al-khwarizmi engineering journal, vol. 16, no. 3, p.p. 2233 (2020) 27 fig. 8. circuit of control system i/o. figure 9 shows the process of compressed air passed from the compressor into the system through plastic pipes to the directional control valves, and the out compressed air from the flow control valves into the system to make the desired movements for the pneumatic cylinders, as illustrated in figure 10. fig. 9. compressed air passing (input compressed air) to the system. fig.10: compressed air passing (output compressed air) from flow control valve into the system. this process is performed when the cylinder is run at every sequence. for the piece to be moved from one location to another should be implemented in several steps. each step has time and coincides with the other step. each axis is moved and synchronized according to the sequence that the system performs to cross the obstacle. using programming arduino should be insert the dimensions of the obstacle to be crossed. it stars from the top or from the side according to its lower dimensions to reduce the time of succession. it is choose the best and least time. as well the most accurate in position and the motion of cylinders will be in terms of the location of the piece and the smooth movement of the cylinders. this is done with several possibilities for three kind of obstacles. these sequences can be programmed in arduino in a specified algorithm as shown in figure11. shahad sarmad khaleel al-khwarizmi engineering journal, vol. 16, no. 3, p.p. 2233 (2020) 28 fig.11. the flowchart of algorithm for arduino program. as the first barrier has a width greater than its height and the other the width is less than its height, then it exceeds the barrier from the lower side after the last and the last barrier is an equal dimensional barrier that exceeds diagonally, and have many cases of combining two or more axes which are three possibilities for each obstacle. these possibilities are: xyz (xy+yz), xyz (xz+yz), and yz. when these possibilities are implemented, they are considered several sequences in two cases, the first case represents the velocity of compressed airflow as a constant, while the second case considers the velocity as changed. therefore; the time for each probability is calculated by writing a program in arduino and outputting the time with the speed and with the distance and a comparison is made between them. a reference sequence is start int x, int y, int z, int n max. x = y = z =100 min. x = y = z =0 n=1… 10 ���������� �� � � � � � � �� � ��� |����� � ������| ��� � � �� � ����� �� � � �� !�"#��= � � �� � ��� if n = [1-10] write |����� � ������|��$ “reference sequence of 1 st obstacle” end shahad sarmad khaleel al-khwarizmi engineering journal, vol. 16, no. 3, p.p. 2233 (2020) 29 made for the first two obstacles and then it is improved by reducing its steps. the following tables explain each sequence steps: table 2, explains the sequences of moving the piece from one place to another by operating each axis separately passing the first obstacle from its eight. table 2, reference sequence for the first obstacle. sequence x y z comment 0 0 0 0 initial state 1 0 1 0 y up 2 0 1 1 z out 3 0 0 1 y down 4 0 1 1 y up 5 1 1 1 x left 6 1 0 1 y down 7 1 1 1 y up 8 0 1 1 x right 9 0 1 0 z in 10 0 0 0 y down improved and reduced sequence from 10 to 8 position steps in table3, by combining the movement of two axes together. table 3, enhanced on table 2 (yz sequence x y z comment 0 0 0 0 initial state 1 0 1 0 y up y down + z out 3 0 1 1 y up 4 1 1 1 x left 5 1 0 1 y down 6 1 1 1 y up 7 0 1 1 x right y down + z in table 4, explains the sequences of moving the piece from one place to another by operating each axis separately passing the second obstacle from its width. table 4, reference sequence for the second obstacle. sequence x y z comment 0 0 0 0 initial state 1 0 1 0 y up 2 0 1 1 z out 3 0 0 1 y down 4 0 0 0 z in 5 1 0 0 x left 6 1 0 1 z out 7 1 0 0 z in 8 0 0 0 x right table 5, enhanced on table 4 (yz) sequence x y z comment 0 0 0 0 initial state 1 0 1 0 y up y down + z out 3 0 1 0 y up + z in 4 1 1 0 x left 5 1 0 1 y down + z out 6 1 0 0 z in 7 0 0 0 x right in tables 6, 7, and 8 the sequences reduced by merged tow axes in different planes yz plane,yx plane and xz plane to be enhancement for early mentioned tables. table 6, enhanced on table 2, xyz (xy+yz). sequence x y z comment 0 0 0 0 initial state 1 0 1 1 y up + z out 2 0 0 1 y down x left + y up x left + y down x right + y up x right + y down + z in 0 1 0 2 8 0 0 0 0 1 0 2 3 1 1 1 1 0 1 4 5 0 1 1 6 0 0 0 shahad sarmad khaleel al-khwarizmi engineering journal, vol. 16, no. 3, p.p. 2233 (2020) 30 table 7, enhanced on table 4, xyz (xz+yz). sequence x y z comment 0 0 0 0 initial state 1 0 1 1 y up + z out 2 0 0 1 y down x left + z in x left + z out x left + z in for third obstacle which is equilateral the process to passed this obstacle performed in 6 sequences as in table8 table 8, enhanced sequence for the third obstacle. sequence x y z comment 0 0 0 0 initial state y up + z out 2 0 0 1 y down x left + y up + z in x left + y down + z out x right + y up + z in x right + y down when executing the above processes tables, the time of each process is calculated and an indication of whether it can be performed in both the fixed and variable speed cases. 6. results and discussion different values are given in time and distance to get the optimum path that the system can take. the curve in figure 12 shows that the time required completing the job that was the most extended way to pick an object and place it in the desired position. curve in figures 13 shows the proposed system need less time with less distance compared to previous, where enhanced preform on yz axes. the curve in figure 14 shows the enhanced in yz and xy axes lead to less time when compared with sequences that only improve in the yz axes, but the system moves in the same distance. all the above enhanced were preform for the first obstacle that refers to table 2. sometimes the enhancement can be done on several axes and sometimes the improvement can occur only on two axes. now for the second obstacle that refers to table 4, the time and distance less than in the first obstacle which can get by enhancement in sequences as the curve shown in figure 15. the curve in figure 16 shows that the enhanced yz axes perform less time with long-distance compared to the reference, and less time with long-distance when compared with enhanced yz axes in the first obstacle. the curve in figure 17 shows the enhanced yz and xz axes for the second obstacle gives less time with long-distance when is compared with the origin and less time with long-distance when is compared with yz-xz for the first obstacle. these differences in values are normal as cannot get less time with a short distance. another consideration parameter such as smooth movements is also important, because any high speed or high pressure may cause a vibration in the system that led to a decreased accuracy. several ways can be used to get the desired results. one of them is the traditional way where only one cylinder moves in each sequence, and the other way is many cylinders move in the same level, such as x-axes with y-axes, x with z, y with z, or all axes move with each other in the same sequence. fig. 12. reference sequence for the first obstacle. 3 0 0 1 1 0 1 4 5 0 0 0 1 0 1 1 3 1 0 1 4 1 0 1 5 1 0 0 6 0 0 0 shahad sarmad khaleel al-khwarizmi engineering journal, vol. 16, no. 3, p.p. 2233 (2020) 31 fig. 13. enhanced sequence (yz) for the first obstacle. fig. 14. enhanced sequence xyz (yz+xy) for the first obstacle. fig. 15. reference sequence for the second obstacle. fig. 16. enhanced sequence (yz) for the second obstacle. fig.17. enhanced sequence xyz (yz+xz) for the second obstacle. 7. conclusion a pick-place system was developed with pneumatic linear double-acting cylinders to applicator in automated systems processes for manufacturing. the most important of automated systems is to improving and increasing production, where the reduction of sequences time of the processes contributes to increasing production. the 3-axes movement was achieved. arduino controls with these axes, through merged between two or three axes according to the selected sequence in the program, sometimes the enhancement can be done on several axes, and sometimes the improvement can occur only on two axes. another consideration parameter such as smooth movements is also important, because any high speed or high pressure may cause a vibration in the system that led to a decreased accuracy. these differences in values are normal as they cannot get less time with a short distance, several ways can be used to get the desired results. shahad sarmad khaleel al-khwarizmi engineering journal, vol. 16, no. 3, p.p. 2233 (2020) 32 8. references [1] a. jahid, s. mustakim, s. sahil, s. shaibaz, and v. d. londhe, “six axis pneumatic materials handling robotic arm,” international research journal of engineering and technology (irjet) vol.5,no.3,pp. 3955–3959, 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[2] k. ahn,“intelligent switching control of pneumatic actuator using on / off solenoid valves,” mechatronics elsevier ltd, vol.15 no.6, pp. 683-702, 2005. [3] t. mravlje, “guidelines for the design of robotic gripping systems,” ljubljana: university of ljubljana, pp. 1-24, 2005. [4] p. verstegen, s. van gastel, and j.w. spronck, “design of a novel single camera vision system for both component and board alignment in pick and place machines,” ifac proceedings volumes (ifac-papers online), vol.4 pp. 706-712, 2006. [5] o. sastr, s. hampapur, “automated pick and place system l,” international conference on mechanical and electrical technology (icmet), pp. 682-686, 2010. [6] y. chui, s. chen, and j. lin, “study of an autonomous fruit picking robot system in greenhouses,” engineering in agiriculture, environment and food, vol.6, no.3, pp. 92-98, 2013. [7] k. mohammed, t. prasad, and, r. mohammed,“design & analysis of a two-jaw parallel pneumatic gripper abstract,” international journal of computational engineering research (ijceronline.com), vol.3,no.12, pp. 41-46, 2013. [8] m. sallom, “stabilizing gap of pole electric arc furnace using smart hydraulic system,” al-khwarizmi engineering journal, vol.11, no.1, p.p.11-18, 2015. [9] c. santosh, c.manoj, a. peddarajula, and et al, “design and fabrication of pneumatic arm for pick and place of cylindrical objects,” international journal of latest technology in engineering, management & applied science (ijltemas) , vol.4, no.5, pp. 111116, 2016. [10] s.dinde, s. kawale, y. parkhe, and et al, “pneumatic arm control using microcontroller,” international journal of advanced research in computer science and software engineering, vol.6,no.4,pp. 681683, 2016. [11] t. deaconescu, a. deaconescu, “pneumatic muscle actuated compliant gripper system,” riceme-17, pp. 1-5, 2017. [12] v. sathishkumar, r. rathish, “four-axis material handling robot using mechanical gripper,” international journal of engineering research & technology (ijert), vol.5, no.14, pp. 1-4, 2017. [13] s. kazemi, h. kharrati, “visual processing and classification of items on moving conveyor with pick and place robot using plc”, intelligent industrial systems , vol.3, no.1, pp. 15-21, 2017. [14] h. hadi, m. salloom, “pneumatic control system of automatic production line using scada implement plc,” al-khwarizmi engineering journal, vol.15, no.3, pp. 16-28, 2019. [15] r. praveen, t. nirmalraja, h. goutham, and et al,“industrial automation system,” advance in electronic and electric engineerin,vol.3, no.6, pp. 717-726, 2013. ���� ��� � � ��� ���� ،3ا���د ،16ا�� �� ا� �� �� ا���ارز�� 2020( 2233( 33 �� ا2 %د ا�01 و.�#,�,� ا+�ى (���%ت ا'&#%ج ا�#� "��� ! �رة ا���ا ا��#�67 ا��.�5!�� !�� #4 !��ة ��3ات !�ا 3� ���� ��� � ***أ+�� ز�2ان ����** �%ھ� 9��2 ��م *� ا��� � ا�������� ا���ارز�� /��� ھ�� ا�� ����اد /� �!" *,*** ا�� $!�'و%$# �� ا���ارز�� /��� ھ�� ا�� ����اد / � �!" ** shahadsarmad36@gmail.com �(')و%�ا+* ا�'�$�: alabasy2001@yahoo.com :�%ا�(')� ا-�$�'و ** ahmadhzaam@yahoo.com*** ا�(')� ا-�$�'و%�: �� ا��= ا6%�!ج. و�$. + �3ال وز)!دة �?� أa)b �. ا�@'وري ا��� ' �. %;!م �?� �ي إ�> %;!م آ�� �8 ��2 !ت ا6%�!ج -%4 )���� ��3ا)! 2!� . أھ��! �/� . "!e ك! ��/� . و�i�2 '(�j ھhه ا-%;� .ھ �� �� ، i� ا ا�hھ h l � � ا� ;!م ا���ف �. ھhا ا� �i ھ� درا� �?� i ا���� �. moل ا� ��n� m���� .ت �� �دة �. ا� �� !ت �8 ��2 وا�eة. �� �/!ور �!����ام ا���ا�?�� �t i / ز)!دة و�� ا�����i ا�hي )?�م � �� ا%�?!ء ووmo .� �qل �/� . ا�����mت �umu i v�� ��( .wt! !د ا� �ًء �2> أ! i? ��/'ك وi������ !ً?8 ا������م. )�� � l h ا� ;!م وا��/$� �4 � tا%!ت ھ�ا�jأ� y� � umu !����ام�م !; ا��'e �8 �$/�ا� ��( .'oإ�> آ ���� .� ���io �?!و�!ت ��� 'ة���� ، jo��u!�� w ز ا��/$� ا���!�n� 8!�� � � (h��� . ��/? w أi@8 ��!ر � ?i ا�� �y ، �. ا�@'وري ا���اt ا+��jا% 2 �ا��?!ر% � . �2ة ����mت. �;�' ا� �!yt ا�����mت ا��� ��� �?!ر%��! �� ا��'"� . � ��nل ا�mo .� ه'(�j� �� يhا� i����ا� iv� ، ��!vا� ا��'2 !; م i?% �8 ا�� �y �. �$!ن إ�> آ�h� .'o] ، �/�!ج � z ا���!%� إ�> �?� i ا�����mت و�!��!�� �?� i ا���� ا�mزم � ?i �/�ر). ، �� �?� i و�� ��!ر ا� .y� ا�� al-khwarizmi engineering!!! journal al-khwarizmi engineering journal, vol. 6, no. 1, pp 1-13 (2010) estimation of extract yield and mass transfer coefficient in solvent extraction of lubricating oil hhuussssaaiinn kk.. hhuussssaaiinn department of chemical engineering/ college of engineering/university of baghdad (received 12 april 2009: accepted 13 july 2009) abstract an investigation was conducted to suggest relations for estimating yield and properties of the improved light lubricating oil fraction produced from furfural extraction process by using specified regression. mass transfer in mixer-settler has been studied. mass transfer coefficient of continuous phase, mass transfer coefficient of dispersed phase and the overall mass transfer coefficient extraction of light lubes oil distillate fraction by furfural are calculated in addition to all physical properties of individual components and the extraction mixtures. the effect of extraction variables were studied such as extraction temperature which ranges from 70 to 110°c and solvent to oil ratio which ranges from 1:1 to 4:1 (wt/wt) were studied. the results of this investigation show that the extract yield e decreased with decreasing solvent to oil ratio in extract layer and increased with increasing temperature. the fraction of total solvent in the raffinate phase decreased with increasing oil to solvent ratio in raffinate layer and increased with increasing temperature. solvent to oil ratio in extract layer decreased with increasing temperature and increased with increasing solvent to charge oil ratio at constant temperature. oil to solvent ratio in raffinate decreased with increasing temperature and increased with increasing solvent to charge oil ratio at constant temperature. estimated functions are the best modeling function for prediction extraction data at various operating conditions. mass transfer coefficient of continuous phase kc and mass transfer coefficient of dispersed phase kd are increased with increasing temperature and solvent charge to oil ratio at constant temperature. the over all mass transfer coefficient kod is increased with increasing temperature and solvent to charge oil ratio; while kod a is increased with temperature and decreased with solvent to charge oil ratio. keywords: mass transfer coefficient, solvent extraction, modeling, lube oil, furfural 1. introduction base oils made from crude petroleum are made up of a great variety of molecules, which contain aromatic rings, naphthenic rings, paraffin and isoparaffin chains. the hydrocarbons found in mineral oils are mainly of three general types: straight and branched–chain paraffinic compounds, polycyclic and fused–ring saturated hydrocarbons based on cyclopentane and cyclohexan prototype ring structures, collectively known as naphthenes, and aromatics, both mono and polynuclear, which are unsaturated ring structures. selective solvent extraction offers a useful method for separating liquid mixtures[1]. because of the large number of organic compounds contained in such mixtures, theoretical knowledge of the extraction equilibria which would be of assistance in the solution of practical problems has been meager. there are many theoretical approaches to the solvent extraction of lubricating oil based on the classical laws of physical chemistry. the errors of extrapolation or interpolation in most of these theories can be traced to the use of distribution coefficients and the assumption that the extract and raffinate fractions are pure compounds. kalichevsky[2] suggested a relation for estimating extract yield for constant number of stages as: log e = (m+nt) log s + (p+qt) …(1) hussain k. hussain! al-khwarizmi engineering journal, vol.6, no.1, pp 1-13 (2010) 2 since both solvent and oil act as solvents for each other, the modified form of eqn.1 for calculating the solvent fraction in the raffinate as[3]: log sr = (a1+bt) log r + (c+ft) …(2) analysis of constant temperature extraction shows that the extraction yield may be expressed as: log e = c log se + cl …(3) and the fraction of the total solvent loss to raffinate is: log sr = k log r + kl …(4) assuming a temperature effect similar to that found by kalichevsky, equations 3 and 4 become: log e = (ml + nl t) log se + (pl +ql t) …(5) log sr = (al +bl t) log r + (cl +fl t) …(6) mass transfer studies in mixer-settler have been mostly confined to estimations of stage efficiency[4, 5]. few investigations report data on mass transfer coefficients kc and kd. the procedure suggested for the estimation of extraction rates in mixer-settlers[6,7] involves the use of the continuous phase coefficient based on solid dissolution studies[6,8,9,10]. as for the application of the solid dissolution model to liquid-liquid systems, jordan[10] has analyzed the results of barker and treybal for liquid-liquid systems by rushton et al.[11]. the calculated continuous phase of coefficient data of rushton et al. showed variation with impeller speed; they could be favourably compared for dispersed phase viscosity of 1 cp with the following equation[6]: kcdt/ dc =0.052 (dr 2 n ρc / µc) 0.833 (µc /ρc dc) 0.5 …(7) the equation was proposed on the bases of data obtained in vessels with dt = 0.5-2.5 ft, dr/ dt = 0.25-0.67 and x = 0.005-0.232. however, for high dispersed phase viscosities, viz. 10,50 and 100 cp, the data of rushton et al.[12] showed wide deviation from the above correlation indicating a pronounced effect due to dispersed phase viscosity as well as impeller speed. the above correlation also fails to correlate data for baffled and unbaffled vessels[13]. on the basis of solid dissolution data, calderbank[8, 9] suggests the following equation for kc: kc (µc / ρc dc) 2/3 = 0.13 ((p/v) µc / ρc 2 )1/4 …(8) the starting point of agitation design is properly a mass transfer coefficient known empirically or from correlations in terms of parameters impeller size and rotation, power input and gas flow rate. few correlations are in the open literature, but some have come from two of the industries that employ aerated stirred tanks on a large scale[14, 15]. the aim of this research is to obtain a representation of lubricating oil extraction system using specified regression that leads to prediction of extract yield and fraction of total solvent in raffinate phase in addition to determining individual mass transfer coefficient of continuous and dispersed phase and over all mass transfer coefficients based on dispersed phase. this is a theoretical research that depends on data base of sadiq[16]. 2. results and discussion figure1 shows the effect of solvent to oil ratio in extract phase se on the extract yield e in different temperatures. the extract yield decreased with decreasing solvent to oil ratio in extract layer because the extraction efficiency of aromatics and poly aromatics decreased with decreasing solvent to charge oil s. figure 1 also shows the increasing of extract yield with increasing temperature but in limitation, solvent extraction of oil is usually carried out at temperatures as close as possible to the miscibility temperature of oil-solvent system in order to reduce the necessary solvent to oil ratio and to operate at the lowest possible viscosity of the oil phase in addition to increasing solubility of undesired compounds in furfural which lead to high extract yield. the extraction temperature 212of is the most close to the miscibility temperature of extraction system in which two phases will be kept immiscible and which allow extraction to be carried out with high extract yield. as temperature increased up to 230of, the extract yield slightly increased which confirms that further increasing in temperature above 212of caused the dropping of extraction efficiency because the miscibility temperature of system exceeded. hussain k. hussain! al-khwarizmi engineering journal, vol.6, no.1, pp 1-13 (2010) 3 0 0.2 0.4 0.6 0.8 1 1.2 2 3 4 5 6 7 8 9 10 solvent to oil ratio in extract layer (se) e x tr a c t y ie ld ( e ) t=158 f t=176 f t=194 f t=212 f t=230 f solvent to oil ratio in extract layer (se) e xt ra ct y ie ld ( e ) fig.1. effect of se on e in extraction of light lube oil by furfural. figure 2 shows the effect of oil to solvent ratio in raffinate layer r on the fraction of total solvent loss to raffinate layer sr in different temperatures. the fraction of total solvent in the raffinate phase decreased with increasing oil to solvent ratio in raffinate layer because the increasing solvent power (solvent to charge oil ratio) at constant temperature gives high extraction efficiency and as solvent power increased, the solvent in raffinate decreased proportionally with the decreasing of raffinate yield of oil which keeps the increase of r. the reverses of extract phase in which solvent increased, in the solvent power also increased. there is no significant effect of increasing temperature on the fraction of total solvent in the raffinate phase. figure 3 shows the effect of temperature on the solvent to oil ratio in extract layer at a given solvent to charge oil ratio. the solvent to oil ratio in extract layer se decreased with increasing temperature because the temperature of the extraction has a very great effect on the solubility characteristics of solvent and increasing extraction temperature increases the solubility of undesired compounds in furfural which lead to high extract yield which necessarily decreases solvent in the extract phase at constant solvent to charge oil ratio. the reverses in raffinate phase in which solvent increased with increasing temperature. while solvent to oil ratio in extract layer increased with increasing solvent to charge oil ratio at constant temperature because the power of solvent dominates. figure 4 shows the effect of temperature on the fraction of total solvent in raffinate layer. sr increased with increasing temperature because as temperature rose close to the miscibility temperature of oil-solvent system which increases the solubility of the undesired compounds in furfural. decreasing raffinate yield of oil necessarily increases solvent in the raffinate phase at constant solvent to charge oil ratio. fraction of total solvent in raffinate layer decreased with increasing solvent to charge oil ratio at constant temperature and the reason is that the dropping of temperature effect and the power of solvent dominates. while oil to solvent ratio in raffinate decreased with increasing temperature because of the reducing solvent for extraction which is increased in raffinate phase rather than extract phase which seems to increase with increasing solvent to charge oil ratio at constant temperature as shown in figure 5. hussain k. hussain! al-khwarizmi engineering journal, vol.6, no.1, pp 1-13 (2010) 4 0 0.05 0.1 0.15 0.2 0.25 0.3 0 5 10 15 20 oil to solvent ratio in raffinate layer (r) t=158 f t=176 f t=194 f t=212 f t=230 f f ra ct io n of t ot al so lv en t l os s to r af fi n at e l ay er ( s r ) fig.2. effect of r on sr in extraction of light lube oil by furfural. fig.3. effect of temperature on the solvent to oil ratio in extract layer. 0 1 2 3 4 5 6 7 8 9 10 150 170 190 210 230 250 temperature(f) s o lv en t to o il r at io i n e xt ra ct l ay er (s e ) ratio 1:1 ratio 2:1 ratio 3:1 ratio 4:1 so lv en t to o il r at io in e xt ra ct l ay er ( s e ) hussain k. hussain! al-khwarizmi engineering journal, vol.6, no.1, pp 1-13 (2010) 5 0 0.05 0.1 0.15 0.2 0.25 0.3 150 160 170 180 190 200 210 220 230 240 temperature(f) f ra ct io n o f t o ta l s o lv en t l o ss to r af fin at e la ye r( s r ) ratio 1:1 ratio 2:1 ratio 3:1 ratio 4:1 f ra ct io n o f t ot al s ol ve nt l os s to r af fi na te l ay er ( s r ) 0 2 4 6 8 10 12 14 16 18 150 170 190 210 230 250 temperature(f) o il t o s o lv en t r at io i n r af fi n at e( r ") ratio 1:1 ratio 2:1 ratio 3:1 ratio 4:1 o il to s ol ve nt r at io in r af fi na te l ay er (r ) fig.4. effect of temperature on the fraction of total solvent in raffinate layer. fig.5. effect of temperature on the oil to solvent ratio in raffinate. hussain k. hussain! al-khwarizmi engineering journal, vol.6, no.1, pp 1-13 (2010) 6 specified regression is applied using the experimental results of extraction lube oil with furfural and that depends on eqns.3-6 as estimated functions and quasi-newton estimation method[17]. this model is applied at optimum extraction temperature 212 of and solvent charge to oil ratio 1-4. figures 6 and 7 show the relations of predicted vs. observed extract yield values. there is a good similarity in 1:1and 2:1 solvent charge to oil ratio; while there is some difference in 3:1 and 4:1. figures 8 and 9 show predicted versus observed fraction of total solvent loss to raffinate layer values. there is an excellent similarity in all range of solvent charge to oil ratio. all statistical values of applied empirical equations are tabulated in table1. the statistical values and figures refer to the high representation of these selective equations to the extraction system where the predicted and observed values are so close. equations 3-6 are good modeling function for prediction extraction data at various operating conditions. table 1, statistical values of estimated functions. log e = 0.75 log se 2.1 log e = (0.2+ 0.005l t) log se + (0.14 0.02 t) log sr = 0.82 log r 0.48 log sr = (0.19 0.01t) log r + (0.14 0.006l t) σ (variance) 90.926% 90.926% 99.929% 99.929% r (correlation factor) 0.954 0.953 0.999 0.999 final loss 0.026 0.026 0.0002 0.0002 e=a*se+b 100c predicted values o bs er ve d v al ue s 0.20 0.25 0.30 0.35 0.40 0.45 0.50 0.55 0.60 0.24 0.30 0.36 0.42 0.48 0.54 fig.6. predicted vs. observed extract yield values of extraction lube oil with furfural. log e = c log se + cl hussain k. hussain! al-khwarizmi engineering journal, vol.6, no.1, pp 1-13 (2010) 7 e=(m+n*100)*se+(p+q*100) predicted values o bs er ve d v al ue s -1.4 -1.3 -1.2 -1.1 -1.0 -0.9 -0.8 -0.7 -0.6 -0.5 -1.4 -1.3 -1.2 -1.1 -1.0 -0.9 -0.8 -0.7 -0.6 fig.7. predicted vs. observed extract yield values of extraction lube oil with furfural. sr=k*r+s 100 predicted values o bs er ve d v al ue s -2.2 -2.0 -1.8 -1.6 -1.4 -1.2 -2.2 -2.0 -1.8 -1.6 -1.4 -1.2 fig.8. predicted vs. observed fraction of total solvent loss to raffinate layer values of extraction lube oil with furfural. log e = (ml + nl t) log se + (pl +ql t) log sr = k log r + kl hussain k. hussain! al-khwarizmi engineering journal, vol.6, no.1, pp 1-13 (2010) 8 sr=(g+d*100)*r+(h+y*100) predicted values o bs er ve d v al ue s -2.2 -2.0 -1.8 -1.6 -1.4 -1.2 -2.2 -2.0 -1.8 -1.6 -1.4 -1.2 fig.9. predicted vs. observed fraction of total solvent loss to raffinate layer values of extraction lube oil with furfural. 3. mass transfer coefficient in mixer-settler mass transfer coefficient of continuous phase is calculated from eqn.7 as follows: kcdt/dc = 0.052(dr 2n ρc / µc) 0.833 (µc / ρc dc) 0.5 …(7) physical properties such as density and viscosity of mixture are calculated from eqns.9&10: ρm = x ρd + (1-x) ρc …(9) µm = (µc / 1-x)(1+ (6x µd / µc+ µd)) …(10) diffusivity coefficients of solute in the continuous and dispersed phase are calculated from eqn.11[18, 19] d = 9.96*10-16 t / µ (v) 1/3 …(11) mass transfer coefficient of dispersed phase is calculated from eqn.12[20]: kd = 17.9 dd/dvs …(12) the volume surface diameter of drops dvs is calculated from eqn.13: dvs= 6x/a …(13) where a is calculated from eqn.14[21]: a=25.9(nwe) 0.5(nre) 0.1(x) 0.84/dr …(14) figures 10 and 11 show the effect of temperature on the mass transfer coefficient of continuous phase kc and dispersed phase kd respectively. mass transfer coefficients of continuous and dispersed phase are increased with increasing temperature and solvent to charge oil ratio. the reason of this temperature effect is that mass transfer coefficient is directly proportional directly and a function of diffusivity which is proportional with temperature increase which necessarily leads to the increase of mass transfer coefficients. the inverse proportion of mass transfer coefficient with viscosity and density decreased with increasing temperature. on the other hand the increase of mass transfer coefficient of dispersed phase with increasing solvent to charge oil ratio at constant temperature caused by the effect of dispersed phase holds up on the interfacial area of drops and then on mean drop size that necessarily has an effect on mass transfer coefficient of dispersed phase. it is noted that the interfacial area of drops decreased with increasing solvent to charge oil ratio (or decreasing dispersed phase hold up) and this caused the mean drop size the decrease, and mass transfer coefficient of dispersed phase to increase in addition to the effect of dispersed phase hold up on density of mixture and in other word on weber number. also mass transfer coefficient of continuous phase increased with increasing solvent to charge oil ratio because the effect of log sr = (al +bl t) log r + (cl +fl t) hussain k. hussain! al-khwarizmi engineering journal, vol.6, no.1, pp 1-13 (2010) 9 hold up of dispersed phase on viscosity of mixture decreased with decreasing hold up at constant temperature that lead to the increasing of mass transfer coefficient of continuous phase. the overall mass transfer coefficient extraction of light lubes oil distillate fraction by furfural is calculated from eqn.15: 1/kod = m/kc+1/kd …(15) figure 12 shows the effect of temperature on the overall mass transfer coefficient kod which increases with increasing temperature and solvent to charge oil ratio; while in figure 13 (kod*a) increases with temperature and decreases with solvent charge to oil ratio. 0 0.1 0.2 0.3 0.4 0.5 0.6 150 170 190 210 230 250 temperature(f) kc (ft /h ) ratio 2:1 ratio 3:1 ratio 4:1 fig.10. effect of temperature on mass transfer coefficient of continuous phase extraction of light lube oil by furfural. 0 0.02 0.04 0.06 0.08 0.1 0.12 150 170 190 210 230 250 temperature(f) k d (f t/ h ) ratio 2:1 ratio 3:1 ratio 4:1 fig.11. effect of temperature on mass transfer coefficient of dispersed phase extraction of light lube oil by furfural. k c (f t/ h ) k d (f t/ h) hussain k. hussain! al-khwarizmi engineering journal, vol.6, no.1, pp 1-13 (2010) 10 0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 150 170 190 210 230 250 temperature(f) k o d (ft /h ) ratio 2:1 ratio 3:1 ratio 4:1 fig.12. effect of temperature on the over all mass transfer coefficient extraction of light lube oil by furfural. 0 20 40 60 80 100 120 140 150 170 190 210 230 250 temperature(f) (k o d )a (h -1 ) ratio 2:1 ratio 3:1 ratio 4:1 fig.13. effect of temperature on the over all mass transfer coefficient extraction of light lube oil by furfural. k od a (h -1 ) k od (f t/ h) hussain k. hussain! al-khwarizmi engineering journal, vol.6, no.1, pp 1-13 (2010) 11 4. conclusions 1. mathematical analysis of solvent extraction equilibria shows that the extraction yield and fraction of total solvent loss to raffinate at constant temperature extraction may be expressed by equation 3 & 4; while assuming temperature effect similar to that found by kalichevsky, the extraction yield and fraction of total solvent loss to raffinate may be expressed by equation 5 & 6. equations 3-6 are good predicting function for extraction data at various operating conditions. 2. operating conditions have a significance effect on the mass transfer coefficient of continuous and dispersed phase which increased with increasing temperature and solvent to charge oil ratio. 3. the overall mass transfer coefficients kod and kod*a are related directly with temperature. they increases with increasing temperature but they differ in their response to solvent to charge oil ratio where kod is increased and kod*a is decreased. nomenclature a interfacial area of drop ft2/ft3 d diffusivity, m2/s dc diffusivity of solute in the continuous phase, ft2/h dd diffusivity of solute in the dispersed phase, ft2/h dr diameter of rotor, ft dt vessel diameter, ft dvs volume surface diameter of drops, ft e extract yield kc individual mass transfer coefficient of continuous phase, ft/h kd individual mass transfer coefficient of dispersed phase, ft/h kod a over all mass transfer coefficient based on dispersed phase, h-1 m equilibrium distribution coefficient n speed of rotor, rph p power consumption.ft ibf / min r ratio of oil to solvent in raffinate phase s solvent to charge oil ratio se ratio of solvent to oil in extract phase sr fraction of total solvent in raffinate phase t temperature, k v solute molar volume, m3/g mol v volume of mixing vessel,ft3 x holdup of the dispersed phase a1, b, al ,bl, c, cl, cl, c, f, k, kl, m, n, ml, nl ,p, pl ,q, ql, constants greek symbols ρc density of continuous phase, ib/ft3 ρm density of mixed phase, ib/ft3 ρd density of dispersed phase, ib/ft3 µ viscosity of mixed phase, pa.s µc viscosity of continuous phase, ib/ft h µm viscosity of mixed phase, ib/ft h 5. references [1] denis, j., briant, j., and hipeaux, j.c., “lubricant properties analysis and testing”, editions technip, paris, 1997. [2] kalichevsky,v.a.,ind.eng.chem.,38,1009(19 46) [3] kalichevsky,v.a.,natl.petroleum news,38,r613(1946) [4] takahashi, k., nii, s., merrories of the school of engineering, nagoya university, science research, 51(1), 1999. [5] wichterlova, j., rod, v., chemical engineering science, 54, 4041(1999). [6] mostaedi,m.,safdari,s. and moosavian,m.,braz.j.chem.eng.,25(3),2008 [7] treybal,r.e.,chem.eng.prog.,60(5),77(1964) ;62(9),67(1966) [8] hossein,a.,mohammad,a. and reza,s.r,iran.j.chem.eng.,25(4)2006. [9] calderbank,p.h. and m.b.mooyoung,chem.eng.,16,39(1961) [10] jordan,d.g.,chem.process development, part 2,new york(1968) hussain k. hussain! al-khwarizmi engineering journal, vol.6, no.1, pp 1-13 (2010) 12 [11] rushton,j.h.s.nagata and t.b.rooney,a.i.cb.e.jl,10,298(1964) [12] rushton,j.h.,e.w.costich and h.j.everett,chem.eng,prog.,52,515(1956) [13] treybal,r.e.,ind.eng.chem.,53,597(1961) [14] stanley,m.w.,"chemical process equipment selection and design",1990 [15] treybal,r.e.,"mass transfer operations",mc graw-hill,new york,1980 [16] sadiq, r. j,m.sc.thesis, baghdad university (2006). [17] stanley,c.l. and mary,c.,"mathematics for engineers and applied scientists",1985 [18] warren,l.m.,julian,c.s,peter,h.,"unit operations of chemical engineering", mc graw-hill,2001 [19] christie,j.g,"transport processes and unit operation",1983 [20] treybal, r. e., chem.eng. proog., 62(9), 67(1966). [21] kafarov, v. v. and m. babanov, zb. prikl. kbim., 32, 789(1959). )2010( 13-1، صفحة 1، العدد 6مجلة الخوارزمي الھندسیة المجلد حسین قاسم حسین 13 عملیة االستخالصتخمین ناتج االستخالص و معامل انتقال المادة في بالمذیب لزیت التزییت حسین قاسم حسین جامعة بغداد/ كلیة الھندسة / الھندسة الكیمیاویةقسم الخالصة ة ن عملی ن م ف المحس ت الخفی ت التزیی الفرفورال تناول ھذا البحث ایجاد عالقات لحساب الناتج والخواص لمقطع زی تخالص ب ودیالت االس تخدام م باس تت .ریاضیة ور المش ي الط ادة ف ال الم ل انتق تمر ومعام ور المس ي الط ادة ف ال الم ل انتق ل تم دراسة انتقال المادة في نظام الخلط والفصل تم حساب معام ومعام ط انتقال المادة الكلي لعملیة االستخالص لمقطع زیت التزیت الخفیف ده وخالئ ى ح ل عل ات ك بواسطة الفرفورال باالضافة الى كل الخواص الفیزیاویة للمركب ر °١١٠الى ٧٠تم دراسة المتغیرات المؤثرة على عملیة االستخالص والتي ھي درجة حرارة االستخالص وتتراوح من . نظام االستخالص ر األخ م، والمتغی . ١:٤ الى ١:١ھو نسبة المذیب الى الزیت وتتراوح من رارة ة الح ادة درج زداد بزی بة . اظھرت نتائج ھذا البحث بان ناتج االستخالص یقل بنقصان نسبة المذیب الى زیت التزییت في طبقة المستخلص وی إن نس رارة ة الح ادة درح ي .المذیب الكلي في طور الرافیینت یقل بزیادة نسبة زیت التزییت الى المذیب في طبقة الرافیینت ویزداد بزی ت ف ى الزی ذیب إل بة الم إن نس ي . یقل بزیادة درجة الحرارة ویزداد بزیادة نسبة المذیب الى زیت التزییت اللقیم بثبوت درجة الحرارةطور االستخالص ذیب ف ى الم ت ال ت التزیی إن نسبة زی .وت درجة الحرارة الرافینیت یقل بزیادة درجة الحرارة ویزداد بزیادة نسبة المذیب الى زیت التزییت اللقیم بثب .ان الدوال الریاضیة التي تم اقتراحھا ھي تعتبر من افضل المودیالت الریاضیة لتمثیل نظام االستخالص ھذا بمختلف الظروف التشغیلیة لى زیت التزییت اللقیم بثبوت یزداد معامل انتقال المادة في الطور المستمر ومعامل انتقال المادة في الطور المشتت بزیادة درجة الحرارة ونسبة المذیب ا بزیادة درجة الحرارة ویقل a kodیزداد معامل انتقال المادة الكلي بزیادة درجة الحرارة ونسبة المذیب الى زیت التزییت اللقیم بینما یزداد. درجة الحرارة .بزیادة نسبة المذیب الى زیت التزییت اللقیم 0 0.2 0.4 0.6 0.8 1 1.2 2345678910 solvent to oil ratio in extract layer (se) extract yield (e) t=158 f t=176 f t=194 f t=212 f t=230 f 0 0.05 0.1 0.15 0.2 0.25 0.3 05101520 oil to solvent ratio in raffinate layer (r) t=158 f t=176 f t=194 f t=212 f t=230 f 0 1 2 3 4 5 6 7 8 9 10 150170190210230250 temperature(f) solvent to oil ratio in extract layer(se) ratio 1:1 ratio 2:1 ratio 3:1 ratio 4:1 linear (ratio 1:1) linear (ratio 2:1) linear (ratio 3:1) linear (ratio 4:1) 0 0.05 0.1 0.15 0.2 0.25 0.3 150160170180190200210220230240 temperature(f) fraction of total solvent loss to raffinate layer(sr) ratio 1:1 ratio 2:1 ratio 3:1 ratio 4:1 series5 series6 series7 linear (ratio 4:1) linear (ratio 3:1) linear (ratio 2:1) linear (ratio 1:1) 0 2 4 6 8 10 12 14 16 18 150170190210230250 temperature(f) oil to solvent ratio in raffinate(r") ratio 1:1 ratio 2:1 ratio 3:1 ratio 4:1 linear (ratio 1:1) linear (ratio 2:1) linear (ratio 4:1) linear (ratio 3:1) e=a*se+b 100c predicted values observed values 0.20 0.25 0.30 0.35 0.40 0.45 0.50 0.55 0.60 0.24 0.30 0.36 0.42 0.48 0.54 e=(m+n*100)*se+(p+q*100) predicted values observed values -1.4 -1.3 -1.2 -1.1 -1.0 -0.9 -0.8 -0.7 -0.6 -0.5 -1.4 -1.3 -1.2 -1.1 -1.0 -0.9 -0.8 -0.7 -0.6 sr=k*r+s 100 predicted values observed values -2.2 -2.0 -1.8 -1.6 -1.4 -1.2 -2.2 -2.0 -1.8 -1.6 -1.4 -1.2 sr=(g+d*100)*r+(h+y*100) predicted values observed values -2.2 -2.0 -1.8 -1.6 -1.4 -1.2 -2.2 -2.0 -1.8 -1.6 -1.4 -1.2 0 0.1 0.2 0.3 0.4 0.5 0.6 150170190210230250 temperature(f) kc(ft/h) ratio 2:1 ratio 3:1 ratio 4:1 0 0.02 0.04 0.06 0.08 0.1 0.12 150170190210230250 temperature(f) kd(ft/h) ratio 2:1 ratio 3:1 ratio 4:1 0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 150170190210230250 temperature(f) kod(ft/h) ratio 2:1 ratio 3:1 ratio 4:1 0 20 40 60 80 100 120 140 150170190210230250 temperature(f) ( kod ) a ( h 1 ) ratio 2:1 ratio 3:1 ratio 4:1 introduction hussain k. hussain al-khwarizmi engineering journal, vol.6, no.1, pp 1-13 (2010) al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 6, no. 1, pp 1-13 (2010) estimation of extract yield and mass transfer coefficient in solvent extraction of lubricating oil hussain k. hussain department of chemical engineering/ college of engineering/university of baghdad (received 12 april 2009: accepted 13 july 2009) abstract an investigation was conducted to suggest relations for estimating yield and properties of the improved light lubricating oil fraction produced from furfural extraction process by using specified regression. mass transfer in mixer-settler has been studied. mass transfer coefficient of continuous phase, mass transfer coefficient of dispersed phase and the overall mass transfer coefficient extraction of light lubes oil distillate fraction by furfural are calculated in addition to all physical properties of individual components and the extraction mixtures. the effect of extraction variables were studied such as extraction temperature which ranges from 70 to 110°c and solvent to oil ratio which ranges from 1:1 to 4:1 (wt/wt) were studied. the results of this investigation show that the extract yield e decreased with decreasing solvent to oil ratio in extract layer and increased with increasing temperature. the fraction of total solvent in the raffinate phase decreased with increasing oil to solvent ratio in raffinate layer and increased with increasing temperature. solvent to oil ratio in extract layer decreased with increasing temperature and increased with increasing solvent to charge oil ratio at constant temperature. oil to solvent ratio in raffinate decreased with increasing temperature and increased with increasing solvent to charge oil ratio at constant temperature. estimated functions are the best modeling function for prediction extraction data at various operating conditions. mass transfer coefficient of continuous phase kc and mass transfer coefficient of dispersed phase kd are increased with increasing temperature and solvent charge to oil ratio at constant temperature. the over all mass transfer coefficient kod is increased with increasing temperature and solvent to charge oil ratio; while kod a is increased with temperature and decreased with solvent to charge oil ratio. keywords: mass transfer coefficient, solvent extraction, modeling, lube oil, furfural 1. introduction base oils made from crude petroleum are made up of a great variety of molecules, which contain aromatic rings, naphthenic rings, paraffin and isoparaffin chains. the hydrocarbons found in mineral oils are mainly of three general types: straight and branched–chain paraffinic compounds, polycyclic and fused–ring saturated hydrocarbons based on cyclopentane and cyclohexan prototype ring structures, collectively known as naphthenes, and aromatics, both mono and polynuclear, which are unsaturated ring structures. selective solvent extraction offers a useful method for separating liquid mixtures[1]. because of the large number of organic compounds contained in such mixtures, theoretical knowledge of the extraction equilibria which would be of assistance in the solution of practical problems has been meager. there are many theoretical approaches to the solvent extraction of lubricating oil based on the classical laws of physical chemistry. the errors of extrapolation or interpolation in most of these theories can be traced to the use of distribution coefficients and the assumption that the extract and raffinate fractions are pure compounds. kalichevsky[2] suggested a relation for estimating extract yield for constant number of stages as: log e = (m+nt) log s + (p+qt) …(1) since both solvent and oil act as solvents for each other, the modified form of eqn.1 for calculating the solvent fraction in the raffinate as[3]: log sr = (a1+bt) log r + (c+ft) …(2) analysis of constant temperature extraction shows that the extraction yield may be expressed as: log e = c log se + cl …(3) and the fraction of the total solvent loss to raffinate is: log sr = k log r + kl …(4) assuming a temperature effect similar to that found by kalichevsky, equations 3 and 4 become: log e = (ml + nl t) log se + (pl +ql t) …(5) log sr = (al +bl t) log r + (cl +fl t) …(6) mass transfer studies in mixer-settler have been mostly confined to estimations of stage efficiency[4, 5]. few investigations report data on mass transfer coefficients kc and kd. the procedure suggested for the estimation of extraction rates in mixer-settlers[6,7] involves the use of the continuous phase coefficient based on solid dissolution studies[6,8,9,10]. as for the application of the solid dissolution model to liquid-liquid systems, jordan[10] has analyzed the results of barker and treybal for liquid-liquid systems by rushton et al.[11]. the calculated continuous phase of coefficient data of rushton et al. showed variation with impeller speed; they could be favourably compared for dispersed phase viscosity of 1 cp with the following equation[6]: kcdt/ dc =0.052 (dr2 n ρc / µc) 0.833 (µc /ρc dc) 0.5 …(7) the equation was proposed on the bases of data obtained in vessels with dt = 0.5-2.5 ft, dr/ dt = 0.25-0.67 and x = 0.005-0.232. however, for high dispersed phase viscosities, viz. 10,50 and 100 cp, the data of rushton et al.[12] showed wide deviation from the above correlation indicating a pronounced effect due to dispersed phase viscosity as well as impeller speed. the above correlation also fails to correlate data for baffled and unbaffled vessels[13]. on the basis of solid dissolution data, calderbank[8, 9] suggests the following equation for kc: kc (µc / ρc dc)2/3 = 0.13 ((p/v) µc / ρc2 )1/4 …(8) the starting point of agitation design is properly a mass transfer coefficient known empirically or from correlations in terms of parameters impeller size and rotation, power input and gas flow rate. few correlations are in the open literature, but some have come from two of the industries that employ aerated stirred tanks on a large scale[14, 15]. the aim of this research is to obtain a representation of lubricating oil extraction system using specified regression that leads to prediction of extract yield and fraction of total solvent in raffinate phase in addition to determining individual mass transfer coefficient of continuous and dispersed phase and over all mass transfer coefficients based on dispersed phase. this is a theoretical research that depends on data base of sadiq[16]. 2. results and discussion figure1 shows the effect of solvent to oil ratio in extract phase se on the extract yield e in different temperatures. the extract yield decreased with decreasing solvent to oil ratio in extract layer because the extraction efficiency of aromatics and poly aromatics decreased with decreasing solvent to charge oil s. figure 1 also shows the increasing of extract yield with increasing temperature but in limitation, solvent extraction of oil is usually carried out at temperatures as close as possible to the miscibility temperature of oil-solvent system in order to reduce the necessary solvent to oil ratio and to operate at the lowest possible viscosity of the oil phase in addition to increasing solubility of undesired compounds in furfural which lead to high extract yield. the extraction temperature 212of is the most close to the miscibility temperature of extraction system in which two phases will be kept immiscible and which allow extraction to be carried out with high extract yield. as temperature increased up to 230of, the extract yield slightly increased which confirms that further increasing in temperature above 212of caused the dropping of extraction efficiency because the miscibility temperature of system exceeded. fig.1. effect of se on e in extraction of light lube oil by furfural. figure 2 shows the effect of oil to solvent ratio in raffinate layer r on the fraction of total solvent loss to raffinate layer sr in different temperatures. the fraction of total solvent in the raffinate phase decreased with increasing oil to solvent ratio in raffinate layer because the increasing solvent power (solvent to charge oil ratio) at constant temperature gives high extraction efficiency and as solvent power increased, the solvent in raffinate decreased proportionally with the decreasing of raffinate yield of oil which keeps the increase of r. the reverses of extract phase in which solvent increased, in the solvent power also increased. there is no significant effect of increasing temperature on the fraction of total solvent in the raffinate phase. figure 3 shows the effect of temperature on the solvent to oil ratio in extract layer at a given solvent to charge oil ratio. the solvent to oil ratio in extract layer se decreased with increasing temperature because the temperature of the extraction has a very great effect on the solubility characteristics of solvent and increasing extraction temperature increases the solubility of undesired compounds in furfural which lead to high extract yield which necessarily decreases solvent in the extract phase at constant solvent to charge oil ratio. the reverses in raffinate phase in which solvent increased with increasing temperature. while solvent to oil ratio in extract layer increased with increasing solvent to charge oil ratio at constant temperature because the power of solvent dominates. figure 4 shows the effect of temperature on the fraction of total solvent in raffinate layer. sr increased with increasing temperature because as temperature rose close to the miscibility temperature of oil-solvent system which increases the solubility of the undesired compounds in furfural. decreasing raffinate yield of oil necessarily increases solvent in the raffinate phase at constant solvent to charge oil ratio. fraction of total solvent in raffinate layer decreased with increasing solvent to charge oil ratio at constant temperature and the reason is that the dropping of temperature effect and the power of solvent dominates. while oil to solvent ratio in raffinate decreased with increasing temperature because of the reducing solvent for extraction which is increased in raffinate phase rather than extract phase which seems to increase with increasing solvent to charge oil ratio at constant temperature as shown in figure 5. fig.2. effect of r on sr in extraction of light lube oil by furfural. fig.3. effect of temperature on the solvent to oil ratio in extract layer. fig.4. effect of temperature on the fraction of total solvent in raffinate layer. fig.5. effect of temperature on the oil to solvent ratio in raffinate. specified regression is applied using the experimental results of extraction lube oil with furfural and that depends on eqns.3-6 as estimated functions and quasi-newton estimation method[17]. this model is applied at optimum extraction temperature 212 of and solvent charge to oil ratio 1-4. figures 6 and 7 show the relations of predicted vs. observed extract yield values. there is a good similarity in 1:1and 2:1 solvent charge to oil ratio; while there is some difference in 3:1 and 4:1. figures 8 and 9 show predicted versus observed fraction of total solvent loss to raffinate layer values. there is an excellent similarity in all range of solvent charge to oil ratio. all statistical values of applied empirical equations are tabulated in table1. the statistical values and figures refer to the high representation of these selective equations to the extraction system where the predicted and observed values are so close. equations 3-6 are good modeling function for prediction extraction data at various operating conditions. table 1, statistical values of estimated functions. log e = 0.75 log se 2.1 log e = (0.2+ 0.005l t) log se + (0.14 0.02 t) log sr = 0.82 log r 0.48 log sr = (0.19 0.01t) log r + (0.14 0.006l t) σ (variance) 90.926% 90.926% 99.929% 99.929% r (correlation factor) 0.954 0.953 0.999 0.999 final loss 0.026 0.026 0.0002 0.0002 fig.6. predicted vs. observed extract yield values of extraction lube oil with furfural. fig.7. predicted vs. observed extract yield values of extraction lube oil with furfural. fig.8. predicted vs. observed fraction of total solvent loss to raffinate layer values of extraction lube oil with furfural. fig.9. predicted vs. observed fraction of total solvent loss to raffinate layer values of extraction lube oil with furfural. 3. mass transfer coefficient in mixer-settler mass transfer coefficient of continuous phase is calculated from eqn.7 as follows: kcdt/dc = 0.052(dr2n ρc / µc) 0.833 (µc / ρc dc) 0.5 …(7) physical properties such as density and viscosity of mixture are calculated from eqns.9&10: ρm = x ρd + (1-x) ρc …(9) µm = (µc / 1-x)(1+ (6x µd / µc+ µd)) …(10) diffusivity coefficients of solute in the continuous and dispersed phase are calculated from eqn.11[18, 19] d = 9.96*10-16 t / µ (v) 1/3 …(11) mass transfer coefficient of dispersed phase is calculated from eqn.12[20]: kd = 17.9 dd/dvs …(12) the volume surface diameter of drops dvs is calculated from eqn.13: dvs= 6x/a …(13) where a is calculated from eqn.14[21]: a=25.9(nwe) 0.5(nre) 0.1(x) 0.84/dr …(14) figures 10 and 11 show the effect of temperature on the mass transfer coefficient of continuous phase kc and dispersed phase kd respectively. mass transfer coefficients of continuous and dispersed phase are increased with increasing temperature and solvent to charge oil ratio. the reason of this temperature effect is that mass transfer coefficient is directly proportional directly and a function of diffusivity which is proportional with temperature increase which necessarily leads to the increase of mass transfer coefficients. the inverse proportion of mass transfer coefficient with viscosity and density decreased with increasing temperature. on the other hand the increase of mass transfer coefficient of dispersed phase with increasing solvent to charge oil ratio at constant temperature caused by the effect of dispersed phase holds up on the interfacial area of drops and then on mean drop size that necessarily has an effect on mass transfer coefficient of dispersed phase. it is noted that the interfacial area of drops decreased with increasing solvent to charge oil ratio (or decreasing dispersed phase hold up) and this caused the mean drop size the decrease, and mass transfer coefficient of dispersed phase to increase in addition to the effect of dispersed phase hold up on density of mixture and in other word on weber number. also mass transfer coefficient of continuous phase increased with increasing solvent to charge oil ratio because the effect of hold up of dispersed phase on viscosity of mixture decreased with decreasing hold up at constant temperature that lead to the increasing of mass transfer coefficient of continuous phase. the overall mass transfer coefficient extraction of light lubes oil distillate fraction by furfural is calculated from eqn.15: 1/kod = m/kc+1/kd …(15) figure 12 shows the effect of temperature on the overall mass transfer coefficient kod which increases with increasing temperature and solvent to charge oil ratio; while in figure 13 (kod*a) increases with temperature and decreases with solvent charge to oil ratio. fig.10. effect of temperature on mass transfer coefficient of continuous phase extraction of light lube oil by furfural. fig.11. effect of temperature on mass transfer coefficient of dispersed phase extraction of light lube oil by furfural. fig.12. effect of temperature on the over all mass transfer coefficient extraction of light lube oil by furfural. fig.13. effect of temperature on the over all mass transfer coefficient extraction of light lube oil by furfural. 4. conclusions 1. mathematical analysis of solvent extraction equilibria shows that the extraction yield and fraction of total solvent loss to raffinate at constant temperature extraction may be expressed by equation 3 & 4; while assuming temperature effect similar to that found by kalichevsky, the extraction yield and fraction of total solvent loss to raffinate may be expressed by equation 5 & 6. equations 3-6 are good predicting function for extraction data at various operating conditions. 2. operating conditions have a significance effect on the mass transfer coefficient of continuous and dispersed phase which increased with increasing temperature and solvent to charge oil ratio. 3. the overall mass transfer coefficients kod and kod*a are related directly with temperature. they increases with increasing temperature but they differ in their response to solvent to charge oil ratio where kod is increased and kod*a is decreased. nomenclature a interfacial area of drop ft2/ft3 d diffusivity, m2/s dc diffusivity of solute in the continuous phase, ft2/h dd diffusivity of solute in the dispersed phase, ft2/h dr diameter of rotor, ft dt vessel diameter, ft dvs volume surface diameter of drops, ft e extract yield kc individual mass transfer coefficient of continuous phase, ft/h kd individual mass transfer coefficient of dispersed phase, ft/h kod a over all mass transfer coefficient based on dispersed phase, h-1 m equilibrium distribution coefficient n speed of rotor, rph p power consumption.ft ibf / min r ratio of oil to solvent in raffinate phase s solvent to charge oil ratio se ratio of solvent to oil in extract phase sr fraction of total solvent in raffinate phase t temperature, k v solute molar volume, m3/g mol v volume of mixing vessel,ft3 x holdup of the dispersed phase a1, b, al ,bl, c, cl, cl, c, f, k, kl, m, n, ml, nl ,p, pl ,q, ql, constants greek symbols ρc density of continuous phase, ib/ft3 ρm density of mixed phase, ib/ft3 ρd density of dispersed phase, ib/ft3 µ viscosity of mixed phase, pa.s µc viscosity of continuous phase, ib/ft h µm viscosity of mixed phase, ib/ft h 5. references [1] denis, j., briant, j., and hipeaux, j.c., “lubricant properties analysis and testing”, editions technip, paris, 1997. [2] kalichevsky,v.a.,ind.eng.chem.,38,1009(1946) [3] kalichevsky,v.a.,natl.petroleum news,38,r-613(1946) [4] takahashi, k., nii, s., merrories of the school of engineering, nagoya university, science research, 51(1), 1999. [5] wichterlova, j., rod, v., chemical engineering science, 54, 4041(1999). [6] mostaedi,m.,safdari,s. and moosavian,m.,braz.j.chem.eng.,25(3),2008 [7] treybal,r.e.,chem.eng.prog.,60(5),77(1964);62(9),67(1966) [8] hossein,a.,mohammad,a. and reza,s.r,iran.j.chem.eng.,25(4)2006. [9] calderbank,p.h. and m.b.moo-young,chem.eng.,16,39(1961) [10] jordan,d.g.,chem.process development, part 2,new york(1968) [11] rushton,j.h.s.nagata and t.b.rooney,a.i.cb.e.jl,10,298(1964) [12] rushton,j.h.,e.w.costich and h.j.everett,chem.eng,prog.,52,515(1956) [13] treybal,r.e.,ind.eng.chem.,53,597(1961) [14] stanley,m.w.,"chemical process equipment selection and design",1990 [15] treybal,r.e.,"mass transfer operations",mc graw-hill,new york,1980 [16] sadiq, r. j,m.sc.thesis, baghdad university (2006). [17] stanley,c.l. and mary,c.,"mathematics for engineers and applied scientists",1985 [18] warren,l.m.,julian,c.s,peter,h.,"unit operations of chemical engineering", mc graw-hill,2001 [19] christie,j.g,"transport processes and unit operation",1983 [20] treybal, r. e., chem.eng. proog., 62(9), 67(1966). [21] kafarov, v. v. and m. babanov, zb. prikl. kbim., 32, 789(1959). تخمين ناتج الاستخلاص و معامل انتقال المادة في عملية الاستخلاص بالمذيب لزيت التزييت حسين قاسم حسين قسم الهندسة الكيمياوية / كلية الهندسة / جامعة بغداد الخلاصة تناول هذا البحث ايجاد علاقات لحساب الناتج والخواص لمقطع زيت التزييت الخفيف المحسن من عملية الاستخلاص بالفرفورال باستخدام موديلات رياضية.تم دراسة انتقال المادة في نظام الخلط والفصل تم حساب معامل انتقال المادة في الطور المستمر ومعامل انتقال المادة في الطور المشتت ومعامل انتقال المادة الكلي لعملية الاستخلاص لمقطع زيت التزيت الخفيف بواسطة الفرفورال بالاضافة الى كل الخواص الفيزياوية للمركبات كل على حده وخلائط نظام الاستخلاص . تم دراسة المتغيرات المؤثرة على عملية الاستخلاص والتي هي درجة حرارة الاستخلاص وتتراوح من 70 الى 110°م، والمتغير الأخر هو نسبة المذيب الى الزيت وتتراوح من 1:1 الى 1:4 . اظهرت نتائج هذا البحث بان ناتج الاستخلاص يقل بنقصان نسبة المذيب الى زيت التزييت في طبقة المستخلص ويزداد بزيادة درجة الحرارة . إن نسبة المذيب الكلي في طور الرافيينت يقل بزيادة نسبة زيت التزييت الى المذيب في طبقة الرافيينت ويزداد بزيادة درحة الحرارة .إن نسبة المذيب إلى الزيت في طور الاستخلاص يقل بزيادة درجة الحرارة ويزداد بزيادة نسبة المذيب الى زيت التزييت اللقيم بثبوت درجة الحرارة. إن نسبة زيت التزييت الى المذيب في الرافينيت يقل بزيادة درجة الحرارة ويزداد بزيادة نسبة المذيب الى زيت التزييت اللقيم بثبوت درجة الحرارة . ان الدوال الرياضية التي تم اقتراحها هي تعتبر من افضل الموديلات الرياضية لتمثيل نظام الاستخلاص هذا بمختلف الظروف التشغيلية. يزداد معامل انتقال المادة في الطور المستمر ومعامل انتقال المادة في الطور المشتت بزيادة درجة الحرارة ونسبة المذيب الى زيت التزييت اللقيم بثبوت درجة الحرارة. يزداد معامل انتقال المادة الكلي بزيادة درجة الحرارة ونسبة المذيب الى زيت التزييت اللقيم بينما يزدادa kod بزيادة درجة الحرارة ويقل بزيادة نسبة المذيب الى زيت التزييت اللقيم. fraction of total solvent loss to raffinate layer (sr) solvent to oil ratio in extract layer (se) fraction of total solvent loss to raffinate layer (sr) solvent to oil ratio in extract layer (se) oil to solvent ratio in raffinate layer (r) k c (ft/h) kd (ft/h) kod (ft/h) kod a (h-1) log e = c log se + cl log e = (ml + nl t) log se + (pl +ql t) log sr = k log r + kl log sr = (al +bl t) log r + (cl +fl t) extract yield (e) � embed pbrush ��� page 6 _1260690138 _1260690492 _1260691110 _1260688596 _1173207870 al-khwarizmi engineering journal al-khwarizmi engineering journal, vol.4 , no.1 , pp 80-89 (2008 ) study the effect of carbon fiber volume fraction and their orientations on the thermal conductivity of the polymer composite materials. dr. mohammed sellab hamza mat. eng. depart university of technology (received ٩ october 2007; accepted 10 january 2008) abstract the effect of fiber volume fraction of the carbon fiber on the thermal conductivity of the polymer composite material was studied. different percentages of carbon fibers were used (5%, 10%, 15%, 20%, and 25%). specimens were made in two groups for unsaturated polyester as a matrix and carbon fibers, first group has parallel arrangement of fibers and the second group has perpendicular arrangement of fibers on the thermal flow, lee's disk method was used for testing the specimens. this study showed that the values of the of thermal conductivity of the specimens when the fibers arranged in parallel direction was higher than that when the fibers arranged in the perpendicular direction the results indicated that the thermal conductivity increases with the increasing the fiber volume fraction. minimum value was (0.٦٤ w/m.c) for parallel arrangement and (0.17١٥ w/m.c) for perpendicular arrangement at (vf = 5%) .maximum value for parallel and perpendicular were (2.٦٥ w/m. c) and (0.2١٥ w/m.c) at (vf = 25%) respectively. keyword: carbon fiber, thermal conductivity, polymer, composite materials. introduction thermal conductivity is defined as the transfer of heat from area of high temperature to that of low temperature. the thermal conductivity of solids materials is greater than that of liquids and gases materials. the thermal conductivity of solid material is four times than that of gases material. this is due to the difference between the voids for two materials. the transfer of the thermal power is depending upon the component of materials. the free electrons are responsible for the transferring the thermal power through the conduct materials, while for the insulating materials such as polymers, the photons is responsible for this phenomena [1]. the fiber volume fraction and their orientation have greater effect on the thermal analysis of the composite specimens. the ability of the composite material to resist or conduct the heating depends on the quantities and qualities of the constituents. the typical applications of epoxy-based fiber-reinforced composite materials are as insulators, mechanical supports and composite tubes in combination with metal tubes as thermal standoffs in large size superconducting underground energy storing magnets to take up compressive loads with minimum thermal loss [2]. oronizo manca et. al. [1] studied the thermal response of the composite materials by evaluating the thermal response of the specimens to different heating conditions. m.w. gaglord [3] said that the composite materials have anisotropic properties; therefore it has high thermal conductivity along the fiber direction and low thermal conductivity in a direction perpendicular to the fiber direction. charles a. sorrell [4] tried to develop new high – performance materials for use in industrial heating application, including glass melting, steel production, …. etc., and the major focus of this project was on optimizing a mohammed sellab al-khwarizmi engineering journal, vol.4 , no. 1 pp 80-89 (2008) ٨١ specific aerogel composite material to the precise thermal mechanical and chemical requirements of a given industrial process. b.w. james and p. harrison [5] used the finite difference method in the calculation of temperature distribution and heat flow in composite materials made from anisotropic materials by taking in to account the local reorientation of the grid and the temperature distribution. heat flow was derived for a composite material made from two materials with anisotropic thermal conductivities. zhan-sheng guo et. al. [6] studied the experimental and numerical temperature distribution of thick polymeric matrix laminates during an autoclaves vacuum bag process. the finite element formulation of transient heat transfer problem was carried out for polymeric matrix composite materials from the heat transfer differential equations. f.rondeaux et.al. [7] developed a specific thermal conductivity measurement facility for solid materials at low temperature where the thermal conductivity measurements on preimpregnated fibers glass epoxy composite are presented in the temperature of 4.2 k to 14 k for different thicknesses in order to extract the thermal boundary resistance. lamees a. khalaf [8] studied the mechanical and physical properties for unsaturated polyester reinforced by fiber glass and nylon fiber composites and found that the thermal conductivity decreases with the increase the volume fraction, it also decrease with increase of nylon fiber layers for the samples of laminar reinforced system. saad m. elie [9] studied the mechanical properties and thermal conductivity for polymer composite material reinforced by aluminum and aluminum oxide particles and found that the thermal conductivity increased with the increase of the weight fraction of metallic and ceramic particles and reach a maximum value of (0.319 w/m.c) for the composite material with (al2o3) reinforced at a weight fraction of (20 %) and reached to (0.407 w/m.c) for the composite material with (al) reinforcement at the same weight fraction. the aim of this research is to study the effect of fiber volume fraction and their orientation (parallel and perpendicular to heat flow) of the reinforcement material (carbon fibers) on the thermal conductivity. the specimens were made from polyester reinforced with five different volume fraction of carbon fiber which is equal to (5%, 10%, 15%, 20% and 25 vol. %). the reinforcement material (carbon fiber) was arranged in two groups. the first group the carbon fibers was aligned in the parallel direction to the thermal flow while the second group the carbon fibers was aligned perpendicular to the thermal flow . theoretical analysis there are two ways for transfer of the thermal energy, 1the vibrating waves of the lattice. 2the movement of the free electrons. the thermal conductivity is defined by the following formula: q= -k dt/dx (1) the equation (1) used only for study state of thermal flow and when the thermal flux does not change with time. the minus sign means that the transfer of heat is starting from hot part to the cold part. the theoretical thermal conductivity is calculated by the following equation [2]:                         2 t s d r 1 1 t s d 2 1 1 d r 2 1 t e s d 1 t 2 t k (2) the loss in heat (e) through the unit time (second) and through the area (m2) is calculated by the following formula [6]:           3 t 3 d 2 t 2 d 2 t 1 t s d 2 1 1 t 1 derπ2 3 t 1 te2rπvi (3) the theoretical thermal conductivity of composite materials is estimated from the following equations [2, 10]:1-when the direction of the thermal flow is parallel to the reinforced material, it is calculated from following equation:m v m k f v f k c1 k  (4) 2-when the direction of the thermal flow is perpendicular; it is obtain from the following formula: mohammed sellab al-khwarizmi engineering journal, vol.4 , no. 1 pp 80-89 (2008) ٨٢ f v m k m v f k m k f k c2 k    …..(5) experimental work in this research, the lee's disk method is used for measuring the thermal conductivity. figure (1) shows the instrument was used for this method. the specimens were made from carbon fibers – polyester matrix materials that have specification illustrated in table (1), and using hand lay-up method for preparation the specimens, the geometry of the specimens are (r=0.02 m), (ds =0.005 m). the specimens reinforced with the carbon fibers parallel to the direction of thermal flow and perpendicular to the thermal flow. temperature of t1, t2, t3 were measured by means of lee`s disk method. the applied voltage and current were (6v) (i=0.2a), to heat the brass disks (2,3) and the temperatures of all disks increases gradually where temperatures recorded every (5 minutes) until reach the equilibrium temperature of all disks. the losses in heat (e) was calculated from equation (3).the thermal conductivity (k) was calculated from equation (2) by using the experimental reading (t1, t2, t3) and the dimension of specimen(r, ds). the theoretical values of the thermal conductivity were obtained from equations (4) and (5). results and discussion table (2) shows the thermal conductivity of the composite specimen when the direction of the thermal flow is parallel to the direction of the carbon fibers. while results of the perpendicular group are shown in table (3). figure (2 and 3) show the relationship between wall surface temperature of the specimen and the time for the fiber volume fraction (vf=5% and vf=25%) respectively for experimental work when the thermal flow in the parallel direction to the direction of the carbon fibers. figure (4&5) show the relationship between wall surface temperature and time for the fiber volume fraction (vf=5% and vf=25%) for experimental work when the thermal flow in the perpendicular direction to the direction of the carbon fibers. it is clear from these figures that the wall surface temperature (t1 and t2) increases in nonlinear relationship with time until it reachs the equilibrium temperature. the relationship between the theoretical thermal conductivity and the volume fraction (vf) for parallel and perpendicular direction of carbon fibers is presented in figure (6), while the relationship for experimental thermal conductivity and the volume fraction shown in figure (7). it can be seen that the results in case of the parallel direction was higher than the results when the fiber arranged in the perpendicular direction to the heat flow. also it can be seen that the difference between the parallel direction and the perpendicular direction increase with increasing the fiber volume fraction figure (8) shows the relationship between the theoretical and experimental thermal conductivity with the volume fraction of carbon fibers for parallel direction, while the relationship for perpendicular direction is illustrated in figure (9). it was found that the maximum difference between the theoretical and the experimental results was ( 8% ) for the parallel direction, this difference is accepted and it is due to the working conditions of the preparation and test of the specimens in the experimental work, while the equation of the theoretical thermal conductivity based on the ideal case. conclusion the main conclusions of this research are: 1the thermal conductivity of composite materials is increasing with increasing of fiber volume fraction(vf ), and for the parallel direction was higher than that for the perpendicular direction. 2the maximum difference between the experimental and theoretical values of the thermal conductivity was (8%) at fiber volume fraction (25%). 3for parallel arrangement, the maximum experimental and theoretical values of the thermal conductivity were (2.٦٥ w/m. c) and (2.8775 w/m. c) respectively ,while for perpendicular were (0.2١٥ w/m. c) and (0.22٦5 w/m. c) at (vf = 25%). mohammed sellab al-khwarizmi engineering journal, vol.4 , no. 1 pp 80-89 (2008) ٨٣ 4the results indicated that the thermal conductivity depends on the method of the arrangement of reinforcement materials. 5the using of reinforcement material (carbon fibers) increased the thermal conductivity of polyester from (0.17 w/m. c) to value (2.8775 w/m. c) at (vf = 25%) of fibers for parallel arrangement, and to (0.22٦5 w/m. c) for perpendicular arrangement. table (1) the properties of polyester and carbon fiber[ 12]. density (g/cm3) modulus of elasticity (gn/m2) poisson's ratio modulus of rigidity (gn/m2) thermal conductivity (w/m. c) polyester 1.04-1.46 2.06-4.41 0.33 0.774-1.657 0.17 carbon fiber 1.78 400 0.32 107.954 15 table (2) thermal conductivity of the composite specimen when the direction of the thermal flow is parallel to the direction of the carbon fibers. thermal conductivity (kc) (w/m. c) fiber volume fraction 5% 10% 15% 20% 25% theoretical (kc) 0.7115 1.253 1.7945 2.336 2.8775 expermintal(kc) ٠.64 ١.١٣ ١.٦٥ ٢.١٥ ٢.٦٥ table (3) thermal conductivity of the composite specimen when the direction of the thermal flow is perpendicular to the direction of the carbon fibers. thermal conductivity (kc) (w/m. c) fiber volume fraction 5% 10% 15% 20% 25% theoretical (kc) 0.1788 0.1885 0.201 0.2١٤٦٨ 0.22٦5 expermintal(kc) ٠.١٧١٥ ٠.١٨٠٥ ٠.١٩٢ ٠.١٢٠٣ ٠.٢١٥ figure (1): test apparatus with specimens test. t2t1 heaterspecimen t3 brass disks mohammed sellab al-khwarizmi engineering journal, vol.4 , no. 1 pp 80-89 (2008) ٨٤ figure (2): relationship between wall surface temperature and time when the fibers arranged in the parallel direction at fiber volume fraction ( vf = 5%) for experimental work. figure (3): relationship between wall surface temperature and time when the fibers arranged in the parallel direction at fiber volume fraction ( vf = 25%) for experimental work. 0 5 10 15 20 25 30 35 40 45 50 time (min.) 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 w al ls u rf ac e t em p er at u re ( c ) parallel direction (vf = 5 %) t2 t1 0 5 10 15 20 25 30 35 40 45 50 55 60 time (min.) 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 w al ls u rf ac e t em p er at u re ( c ) parallel direction (vf = 25 %) t2 t1  mohammed sellab al-khwarizmi engineering journal, vol.4 , no. 1 pp 80-89 (2008) ٨٥ figure (4): relationship between wall surface temperature and time when the fibers arranged in the perpendicular direction at fiber volume fraction ( vf = 5%) for experimental work. figure (5): relationship between wall surface temperature and time when the fibers arranged in the perpendicular direction at fiber volume fraction ( vf = 25%) for experimental work. 0 5 10 15 20 25 30 35 40 45 time (min.) 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 w al ls u rf ac e t em p er at u re ( c ) perpedicular direction (vf = 5 %) t2 t1 0 5 10 15 20 25 30 35 40 45 50 55 60 time (min.) 28 30 32 34 36 38 40 42 44 46 48 50 52 54 56 w al ls u rf ac e t em p er at u re ( c ) perpedicular direction (vf = 25 %) t2 t1 mohammed sellab al-khwarizmi engineering journal, vol.4 , no. 1 pp 80-89 (2008) ٨٦ figure (6): relationship between the theoretical thermal conductivity and the volume fraction for parallel and perpendicular direction. figure (7): relationship between the experimental thermal conductivity and the volume fraction for parallel and perpendicular direction. 5 10 15 20 25 volume fraction (%) 0.0 0.5 1.0 1.5 2.0 2.5 3.0 t h er m al c o n d u ct iv it y ( w /m . c ) theoretical parallel direction perpendicular direction  5 10 15 20 25 volume fraction (%) 0.0 0.5 1.0 1.5 2.0 2.5 3.0 t h er m al c o n d u ct iv it y ( w /m . c ) experimental parallel direction perpendicular direction  mohammed sellab al-khwarizmi engineering journal, vol.4 , no. 1 pp 80-89 (2008) ٨٧ figure (8): relationship between the thermal conductivity and the volume fraction for parallel direction. figure (9): relationship between the thermal conductivity and the volume fraction for perpendicular direction. 5 10 15 20 25 volume fraction (%) 0.0 0.5 1.0 1.5 2.0 2.5 3.0 t h er m al c o n d u ct iv it y ( w /m . c ) theoretical experimental 5 10 15 20 25 volume fraction (%) 0.10 0.15 0.20 0.25 0.30 t h er m a lc o n d u ct iv it y ( w /m . c ) theoretical experimental mohammed sellab al-khwarizmi engineering journal, vol.4 , no. 1 pp 80-89 (2008) ٨٨ notation d1, d2&d3 thickness of the brass disks (m) ds thickness of the composite specimen (m) e convection heat transfer coefficient (w/m2. c) k thermal conductivity (w/m. c) kc1 thermal conductivity of the composite specimen in the parallel direction of the fibers (w/m. c) kc2 thermal conductivity of the composite specimen in the perpendicular direction of the fibers (w/m. c) kf, km thermal conductivity of fibers and matrix (w/m. c) q heat flux. r radius of specimen (m) t1, t2,t3 temperature across the copper disks(1,2,3) (c) vf volume fraction of fibers (%) vm volume fraction of matrix (%) dt/dx temperature gradient references [1-] oronzio manca, biagio morrone, giuseppe romano, “analysis of thermal response of composite materials “, dipartimento ingegneria aerospaziale e meccanica, http://event.ua.pt/ds2005/manca3.pdf., italy, (2005). [2-] bsr murthy, dr. a. rama krishna and b.v rama krishna,” thermal analysis of epoxy based fiber-reinforced”, ie(i) journal – mc, vol.84,april, (2004). [3-] m.w. gaglord, “reinforced plastic; theory and practice “,2nd edition, chahnenrs put. co. inc., (1974). [4-] charles a sorrell, “advanced nanoporous composite materials for industrial heating applications”, applied sciences laboratory, inc., http://www.eere.energy.gov/industry/imf/pd fs/ibni.composite. pdf., (2002) [5-] b.w. james and p. harrison,” analysis of the temperature distribution, heat flow and effective thermal conductivity of homogenous composite materials with anisotropic thermal conductivity”, journal of physics, vol.d, applied physics, issue 9, sept. (1992). [6-] zhan – sheng guo, shanyi du and boming zhang, “temperature distribution of the thick thermoset composite”, journal of modeling and simulation in materials science and engineering, volume 12, issue 3, (china) may, (2004). [7-] f. rondeaux, ph. bready and j.m. rey, “thermal conductivity measurements of epoxy systems at low temperature”, cryogenic engineering conference (cec), (usa), july (2001). [8-] lamees a. khalaf, "studying the mechanical and physical properties for unsaturated polyester reinforced by fiber glass and nylon fiber composites", m.sc. thesis, university of technology, materials engineering department (2006). [9-] saad m. elie, "studied the mechanical properties and thermal conductivity for polymer composite material reinforced by aluminum and aluminum oxide particles", m.sc. thesis, university of technology, materials engineering department (2007) . [10-] r.m. jones,” mechanics of composite materials”, mcgraw-hill, new york, (1975). [11-] w. bolton,” engineering materials technology”, butterworth – heinemann, third edition, (1998). [12-] william d. callister,” materials science and engineering an introduction”, sixth edition, john wiley and sons, inc., (2003). mohammed sellab al-khwarizmi engineering journal, vol.4 , no. 1 pp 80-89 (2008) ٨٩ الموصلیة الحراریة للمواد المتراكبة واتجاھھا على الكربونأللیاف ألحجمي دراسة تأثیر الكسر البولیمریة الدكتور المھندس محمد صالب حمزة الجامعة التكنولوجیبة قسم ھندسة المواد :الخالصة یلة % ) ٥,%١٠,%١٥,%٢٠,%٢٥(ة تم في ھذا البحث دراسة تأثیر الكسر الحجمي اللیاف الكاربون وبنسب مختلف ى التوص عل اربون . الحراریة للمادة المتراكبة اف الك ي . حیث صنعت العینات من مادة البولي أستر غیر المشبع المقواة بالی نعت ف ات ص العین ة ال ا المجموع راري، ام یاب الح وازي لالنس كل م ة بش اربون مرتب اف الك ت مجموعتین المجموعة االولى كانت فیھا الی ة نظم ثانی .بترتیب االلیاف بشكل عمودي على االنسیاب الحراري ة . في فحص العینات) leeś disk(استخدمت طریقة قرص لي اثبتت الدراسة ان الترتیب الموازي لاللیاف یعطي موصلیة حراری ادة المترا . اعلى من الترتیب العمودي اف وبینت النتائج بان الموصلیة الحراریة للم ي لاللی ر الحجم ادة الكس ع زی زداد م ة ت وان . كب ت وازي و ) w/m.c 0.64(اقل قیمة للموصلیة الحراریة كان ب الم ر ) ٠.١٧١٥ w/m.c(للترتی د الكس ودي عن ب العم للترتی ي ت ) vf=5%(الحجم ة كان ى قیم ا اعل ام )2.65 w/m.c ( للترتیب الموازي و)0.215 w/m.c (ر حجمي العمودي عند كسللترتیب)vf = 25%(. 0 5 1 0 1 5 2 0 2 5 3 0 3 5 4 0 4 5 5 0 t i m e ( m i n . ) 2 8 3 0 3 2 3 4 3 6 3 8 4 0 4 2 4 4 4 6 4 8 5 0 5 2 5 4 5 6 w a l l s u r f a c e t e m p e r a t u r e ( c ) p a r a l l e l d i r e c t i o n ( v f = 5 % ) t 2 t 1 05101520253035404550 time (min.) 28 30 32 34 36 38 40 42 44 46 48 50 52 5456w a l l s u r f a c e t e m p e r a t u r e ( c ) parallel direction (vf = 5 %) t2 t1 0 5 1 0 1 5 2 0 2 5 3 0 3 5 4 0 4 5 5 0 5 5 6 0 t i m e ( m i n . ) 2 8 3 0 3 2 3 4 3 6 3 8 4 0 4 2 4 4 4 6 4 8 5 0 5 2 5 4 5 6 w a l l s u r f a c e t e m p e r a t u r e ( c ) p a r a l l e l d i r e c t i o n ( v f = 2 5 % ) t 2 t 1 051015202530354045505560 time (min.) 28 30 32 34 36 38 40 42 44 46 48 50 52 5456w a l l s u r f a c e t e m p e r a t u r e ( c ) parallel direction (vf = 25 %) t2 t1 0 5 1 0 1 5 2 0 2 5 3 0 3 5 4 0 4 5 t i m e ( m i n . ) 2 8 3 0 3 2 3 4 3 6 3 8 4 0 4 2 4 4 4 6 4 8 5 0 5 2 5 4 5 6 w a l l s u r f a c e t e m p e r a t u r e ( c ) p e r p e d i c u l a r d i r e c t i o n ( v f = 5 % ) t 2 t 1 051015202530354045 time (min.) 28 30 32 34 36 38 40 42 44 46 48 50 52 5456w a l l s u r f a c e t e m p e r a t u r e ( c ) perpedicular direction (vf = 5 %) t2 t1 ú û ù ê ë é × × + × ÷ ø ö ç è æ + × + × = ú ú û ù ê ê ë é × 2 t s d r 1 1 t s d 2 1 1 d r 2 1 t e s d 1 t 2 t k ( ) ( ) ú û ù ê ë é × + × + + × + × × × × × + + × × × = × 3 t 3 d 2 t 2 d 2 t 1 t s d 2 1 1 t 1 d e r π 2 3 t 1 t e 2 r π v i m v m k f v f k c1 k × + × = f v m k m v f k m k f k c2 k × + × × = 0 5 1 0 1 5 2 0 2 5 3 0 3 5 4 0 4 5 5 0 5 5 6 0 t i m e ( m i n . ) 2 8 3 0 3 2 3 4 3 6 3 8 4 0 4 2 4 4 4 6 4 8 5 0 5 2 5 4 5 6 w a l l s u r f a c e t e m p e r a t u r e ( c ) p e r p e d i c u l a r d i r e c t i o n ( v f = 2 5 % ) t 2 t 1 051015202530354045505560 time (min.) 28 30 32 34 36 38 40 42 44 46 48 50 52 5456w a l l s u r f a c e t e m p e r a t u r e ( c ) perpedicular direction (vf = 25 %) t2 t1 5 1 0 1 5 2 0 2 5 v o l u m e f r a c t i o n ( % ) 0 . 0 0 . 5 1 . 0 1 . 5 2 . 0 2 . 5 3 . 0 t h e r m a l c o n d u c t i v i t y ( w / m . c ) t h e o r e t i c a l p a r a l l e l d i r e c t i o n p e r p e n d i c u l a r d i r e c t i o n 51015 20 25 volume fraction (%) 0.0 0.5 1.0 1.5 2.0 2.5 3.0t h e r m a l c o n d u c t i v i t y ( w / m . c ) theoretical parallel direction perpendicular direction 5 1 0 1 5 2 0 2 5 v o l u m e f r a c t i o n ( % ) 0 . 0 0 . 5 1 . 0 1 . 5 2 . 0 2 . 5 3 . 0 t h e r m a l c o n d u c t i v i t y ( w / m . c ) e x p e r i m e n t a l p a r a l l e l d i r e c t i o n p e r p e n d i c u l a r d i r e c t i o n 51015 20 25 volume fraction (%) 0.0 0.5 1.0 1.5 2.0 2.5 3.0t h e r m a l c o n d u c t i v i t y ( w / m . c ) experimental parallel direction perpendicular direction 5 1 0 1 5 2 0 2 5 v o l u m e f r a c t i o n ( % ) 0 . 0 0 . 5 1 . 0 1 . 5 2 . 0 2 . 5 3 . 0 t h e r m a l c o n d u c t i v i t y ( w / m . c ) t h e o r e t i c a l e x p e r i m e n t a l 51015 20 25 volume fraction (%) 0.0 0.5 1.0 1.5 2.0 2.5 3.0t h e r m a l c o n d u c t i v i t y ( w / m . c ) theoretical experimental 5 1 0 1 5 2 0 2 5 v o l u m e f r a c t i o n ( % ) 0 . 1 0 0 . 1 5 0 . 2 0 0 . 2 5 0 . 3 0 t h e r m a l c o n d u c t i v i t y ( w / m . c ) t h e o r e t i c a l e x p e r i m e n t a l 51015 20 25 volume fraction (%) 0.10 0.15 0.20 0.25 0.30t h e r m a l c o n d u c t i v i t y ( w / m . c ) theoretical experimental abstract mohammed sellab al-khwarizmi engineering journal, vol.4 , no. 1 pp 80-89 (2008) al-khwarizmi engineering journal al-khwarizmi engineering journal, vol.4 , no.1 , pp 80-89 (2008 ) study the effect of carbon fiber volume fraction and their orientations on the thermal conductivity of the polymer composite materials. dr. mohammed sellab hamza mat. eng. depart university of technology (received 9 october 2007; accepted 10 january 2008) abstract the effect of fiber volume fraction of the carbon fiber on the thermal conductivity of the polymer composite material was studied. different percentages of carbon fibers were used (5%, 10%, 15%, 20%, and 25%). specimens were made in two groups for unsaturated polyester as a matrix and carbon fibers, first group has parallel arrangement of fibers and the second group has perpendicular arrangement of fibers on the thermal flow, lee's disk method was used for testing the specimens. this study showed that the values of the of thermal conductivity of the specimens when the fibers arranged in parallel direction was higher than that when the fibers arranged in the perpendicular direction the results indicated that the thermal conductivity increases with the increasing the fiber volume fraction. minimum value was (0.64 w/m.(c) for parallel arrangement and (0.1715 w/m.(c) for perpendicular arrangement at (vf = 5%) .maximum value for parallel and perpendicular were (2.65 w/m. (c) and (0.215 w/m.(c) at (vf = 25%) respectively. keyword: carbon fiber, thermal conductivity, polymer, composite materials. introduction thermal conductivity is defined as the transfer of heat from area of high temperature to that of low temperature. the thermal conductivity of solids materials is greater than that of liquids and gases materials. the thermal conductivity of solid material is four times than that of gases material. this is due to the difference between the voids for two materials. the transfer of the thermal power is depending upon the component of materials. the free electrons are responsible for the transferring the thermal power through the conduct materials, while for the insulating materials such as polymers, the photons is responsible for this phenomena [1]. the fiber volume fraction and their orientation have greater effect on the thermal analysis of the composite specimens. the ability of the composite material to resist or conduct the heating depends on the quantities and qualities of the constituents. the typical applications of epoxy-based fiber-reinforced composite materials are as insulators, mechanical supports and composite tubes in combination with metal tubes as thermal standoffs in large size super-conducting underground energy storing magnets to take up compressive loads with minimum thermal loss [2]. oronizo manca et. al. [1] studied the thermal response of the composite materials by evaluating the thermal response of the specimens to different heating conditions. m.w. gaglord [3] said that the composite materials have anisotropic properties; therefore it has high thermal conductivity along the fiber direction and low thermal conductivity in a direction perpendicular to the fiber direction. charles a. sorrell [4] tried to develop new high – performance materials for use in industrial heating application, including glass melting, steel production, …. etc., and the major focus of this project was on optimizing a specific aerogel composite material to the precise thermal mechanical and chemical requirements of a given industrial process. b.w. james and p. harrison [5] used the finite difference method in the calculation of temperature distribution and heat flow in composite materials made from anisotropic materials by taking in to account the local re-orientation of the grid and the temperature distribution. heat flow was derived for a composite material made from two materials with anisotropic thermal conductivities. zhan-sheng guo et. al. [6] studied the experimental and numerical temperature distribution of thick polymeric matrix laminates during an autoclaves vacuum bag process. the finite element formulation of transient heat transfer problem was carried out for polymeric matrix composite materials from the heat transfer differential equations. f.rondeaux et.al. [7] developed a specific thermal conductivity measurement facility for solid materials at low temperature where the thermal conductivity measurements on pre-impregnated fibers glass epoxy composite are presented in the temperature of 4.2 k to 14 k for different thicknesses in order to extract the thermal boundary resistance. lamees a. khalaf [8] studied the mechanical and physical properties for unsaturated polyester reinforced by fiber glass and nylon fiber composites and found that the thermal conductivity decreases with the increase the volume fraction, it also decrease with increase of nylon fiber layers for the samples of laminar reinforced system. saad m. elie [9] studied the mechanical properties and thermal conductivity for polymer composite material reinforced by aluminum and aluminum oxide particles and found that the thermal conductivity increased with the increase of the weight fraction of metallic and ceramic particles and reach a maximum value of (0.319 w/m.(c) for the composite material with (al2o3) reinforced at a weight fraction of (20 %) and reached to (0.407 w/m.(c) for the composite material with (al) reinforcement at the same weight fraction. the aim of this research is to study the effect of fiber volume fraction and their orientation (parallel and perpendicular to heat flow) of the reinforcement material (carbon fibers) on the thermal conductivity. the specimens were made from polyester reinforced with five different volume fraction of carbon fiber which is equal to (5%, 10%, 15%, 20% and 25 vol. %). the reinforcement material (carbon fiber) was arranged in two groups. the first group the carbon fibers was aligned in the parallel direction to the thermal flow while the second group the carbon fibers was aligned perpendicular to the thermal flow . theoretical analysis there are two ways for transfer of the thermal energy, 1the vibrating waves of the lattice. 2the movement of the free electrons. the thermal conductivity is defined by the following formula: q= -k dt/dx (1) the equation (1) used only for study state of thermal flow and when the thermal flux does not change with time. the minus sign means that the transfer of heat is starting from hot part to the cold part. the theoretical thermal conductivity is calculated by the following equation [2]: (2) the loss in heat (e) through the unit time (second) and through the area (m2) is calculated by the following formula [6]: (3) the theoretical thermal conductivity of composite materials is estimated from the following equations [2, 10]:1-when the direction of the thermal flow is parallel to the reinforced material, it is calculated from following equation:(4) 2-when the direction of the thermal flow is perpendicular; it is obtain from the following formula: …..(5) experimental work in this research, the lee's disk method is used for measuring the thermal conductivity. figure (1) shows the instrument was used for this method. the specimens were made from carbon fibers – polyester matrix materials that have specification illustrated in table (1), and using hand lay-up method for preparation the specimens, the geometry of the specimens are (r=0.02 m), (ds =0.005 m). the specimens reinforced with the carbon fibers parallel to the direction of thermal flow and perpendicular to the thermal flow. temperature of t1, t2, t3 were measured by means of lee`s disk method. the applied voltage and current were (6v) (i=0.2a), to heat the brass disks (2,3) and the temperatures of all disks increases gradually where temperatures recorded every (5 minutes) until reach the equilibrium temperature of all disks. the losses in heat (e) was calculated from equation (3).the thermal conductivity (k) was calculated from equation (2) by using the experimental reading (t1, t2, t3) and the dimension of specimen(r, ds). the theoretical values of the thermal conductivity were obtained from equations (4) and (5). results and discussion table (2) shows the thermal conductivity of the composite specimen when the direction of the thermal flow is parallel to the direction of the carbon fibers. while results of the perpendicular group are shown in table (3). figure (2 and 3) show the relationship between wall surface temperature of the specimen and the time for the fiber volume fraction (vf=5% and vf=25%) respectively for experimental work when the thermal flow in the parallel direction to the direction of the carbon fibers. figure (4&5) show the relationship between wall surface temperature and time for the fiber volume fraction (vf=5% and vf=25%) for experimental work when the thermal flow in the perpendicular direction to the direction of the carbon fibers. it is clear from these figures that the wall surface temperature (t1 and t2) increases in nonlinear relationship with time until it reachs the equilibrium temperature. the relationship between the theoretical thermal conductivity and the volume fraction (vf) for parallel and perpendicular direction of carbon fibers is presented in figure (6), while the relationship for experimental thermal conductivity and the volume fraction shown in figure (7). it can be seen that the results in case of the parallel direction was higher than the results when the fiber arranged in the perpendicular direction to the heat flow. also it can be seen that the difference between the parallel direction and the perpendicular direction increase with increasing the fiber volume fraction figure (8) shows the relationship between the theoretical and experimental thermal conductivity with the volume fraction of carbon fibers for parallel direction, while the relationship for perpendicular direction is illustrated in figure (9). it was found that the maximum difference between the theoretical and the experimental results was ( 8% ) for the parallel direction, this difference is accepted and it is due to the working conditions of the preparation and test of the specimens in the experimental work, while the equation of the theoretical thermal conductivity based on the ideal case. conclusion the main conclusions of this research are: 1the thermal conductivity of composite materials is increasing with increasing of fiber volume fraction(vf ), and for the parallel direction was higher than that for the perpendicular direction. 2the maximum difference between the experimental and theoretical values of the thermal conductivity was (8%) at fiber volume fraction (25%). 3for parallel arrangement, the maximum experimental and theoretical values of the thermal conductivity were (2.65 w/m. (c) and (2.8775 w/m. (c) respectively ,while for perpendicular were (0.215 w/m. (c) and (0.2265 w/m. (c) at (vf = 25%). 4the results indicated that the thermal conductivity depends on the method of the arrangement of reinforcement materials. 5the using of reinforcement material (carbon fibers) increased the thermal conductivity of polyester from (0.17 w/m. (c) to value (2.8775 w/m. (c) at (vf = 25%) of fibers for parallel arrangement, and to (0.2265 w/m. (c) for perpendicular arrangement. table (1) the properties of polyester and carbon fiber[ 12]. density (g/cm3) modulus of elasticity (gn/m2) poisson's ratio modulus of rigidity (gn/m2) thermal conductivity (w/m. c() polyester 1.04-1.46 2.06-4.41 0.33 0.774-1.657 0.17 carbon fiber 1.78 400 0.32 107.954 15 table (2) thermal conductivity of the composite specimen when the direction of the thermal flow is parallel to the direction of the carbon fibers. thermal conductivity (kc) (w/m. c() fiber volume fraction 5% 10% 15% 20% 25% theoretical (kc) 0.7115 1.253 1.7945 2.336 2.8775 expermintal(kc) 0.64 1.13 1.65 2.15 2.65 table (3) thermal conductivity of the composite specimen when the direction of the thermal flow is perpendicular to the direction of the carbon fibers. thermal conductivity (kc) (w/m. c() fiber volume fraction 5% 10% 15% 20% 25% theoretical (kc) 0.1788 0.1885 0.201 0.21468 0.2265 expermintal(kc) 0.1715 0.1805 0.192 0.1203 0.215 figure (1): test apparatus with specimens test. figure (2): relationship between wall surface temperature and time when the fibers arranged in the parallel direction at fiber volume fraction ( vf = 5%) for experimental work. figure (3): relationship between wall surface temperature and time when the fibers arranged in the parallel direction at fiber volume fraction ( vf = 25%) for experimental work. figure (4): relationship between wall surface temperature and time when the fibers arranged in the perpendicular direction at fiber volume fraction ( vf = 5%) for experimental work. figure (5): relationship between wall surface temperature and time when the fibers arranged in the perpendicular direction at fiber volume fraction ( vf = 25%) for experimental work. figure (6): relationship between the theoretical thermal conductivity and the volume fraction for parallel and perpendicular direction. figure (7): relationship between the experimental thermal conductivity and the volume fraction for parallel and perpendicular direction. figure (8): relationship between the thermal conductivity and the volume fraction for parallel direction. figure (9): relationship between the thermal conductivity and the volume fraction for perpendicular direction. notation d1, d2&d3 thickness of the brass disks (m) ds thickness of the composite specimen (m) e convection heat transfer coefficient (w/m2. (c) k thermal conductivity (w/m. (c) kc1 thermal conductivity of the composite specimen in the parallel direction of the fibers (w/m. (c) kc2 thermal conductivity of the composite specimen in the perpendicular direction of the fibers (w/m. (c) kf, km thermal conductivity of fibers and matrix (w/m. (c) q heat flux. r radius of specimen (m) t1, t2,t3 temperature across the copper disks(1,2,3) ((c) vf volume fraction of fibers (%) vm volume fraction of matrix (%) dt/dx temperature gradient references [1-] oronzio manca, biagio morrone, giuseppe romano, “analysis of thermal response of composite materials “, dipartimento ingegneria aerospaziale e meccanica, http://event.ua.pt/ds2005/manca3.pdf., italy, (2005). [2-] bsr murthy, dr. a. rama krishna and b.v rama krishna,” thermal analysis of epoxy based fiber-reinforced”, ie(i) journal – mc, vol.84,april, (2004). [3-] m.w. gaglord, “reinforced plastic; theory and practice “,2nd edition, chahnenrs put. co. inc., (1974). [4-] charles a sorrell, “advanced nanoporous composite materials for industrial heating applications”, applied sciences laboratory, inc., http://www.eere.energy.gov/industry/imf/pdfs/ibni.composite. pdf., (2002) [5-] b.w. james and p. harrison,” analysis of the temperature distribution, heat flow and effective thermal conductivity of homogenous composite materials with anisotropic thermal conductivity”, journal of physics, vol.d, applied physics, issue 9, sept. (1992). [6-] zhan – sheng guo, shanyi du and boming zhang, “temperature distribution of the thick thermoset composite”, journal of modeling and simulation in materials science and engineering, volume 12, issue 3, (china) may, (2004). [7-] f. rondeaux, ph. bready and j.m. rey, “thermal conductivity measurements of epoxy systems at low temperature”, cryogenic engineering conference (cec), (usa), july (2001). [8-] lamees a. khalaf, "studying the mechanical and physical properties for unsaturated polyester reinforced by fiber glass and nylon fiber composites", m.sc. thesis, university of technology, materials engineering department (2006). [9-] saad m. elie, "studied the mechanical properties and thermal conductivity for polymer composite material reinforced by aluminum and aluminum oxide particles", m.sc. thesis, university of technology, materials engineering department (2007) . [10-] r.m. jones,” mechanics of composite materials”, mcgraw-hill, new york, (1975). [11-] w. bolton,” engineering materials technology”, butterworth – heinemann, third edition, (1998). [12-] william d. callister,” materials science and engineering an introduction”, sixth edition, john wiley and sons, inc., (2003). دراسة تأثير الكسر ألحجمي لألياف الكربون واتجاهها على الموصلية الحرارية للمواد المتراكبة البوليمرية الدكتور المهندس محمد صلاب حمزة الجامعة التكنولوجيبة قسم هندسة المواد الخلاصة: تم في هذا البحث دراسة تأثير الكسر الحجمي لالياف الكاربون وبنسب مختلفة (25%,20%,15%,10%,5% ) على التوصيلة الحرارية للمادة المتراكبة. حيث صنعت العينات من مادة البولي أستر غير المشبع المقواة بالياف الكاربون . العينات صنعت في مجموعتين المجموعة الاولى كانت فيها الياف الكاربون مرتبة بشكل موازي للانسياب الحراري، اما المجموعة الثانية نظمت بترتيب الالياف بشكل عمودي على الانسياب الحراري . استخدمت طريقة قرص لي (leeś disk ) في فحص العينات. اثبتت الدراسة ان الترتيب الموازي للالياف يعطي موصلية حرارية اعلى من الترتيب العمودي. وبينت النتائج بان الموصلية الحرارية للمادة المتراكبة تزداد مع زيادة الكسر الحجمي للالياف. وان اقل قيمة للموصلية الحرارية كانت ( 0.64 w/m.(c) للترتيب الموازي و (w/m.(c 0.1715) للترتيب العمودي عند الكسر الحجمي (vf=5% ) اما اعلى قيمة كانت (2.65 w/m.(c) للترتيب الموازي و (0.215 w/m.(c) للترتيب العمودي عند كسر حجمي (vf = 25%) . t2 t1 heater specimen t3 brass disks ( ( ( ( ( ( ( ( � embed pbrush ��� page 81 _1260554148.unknown _1260554197.unknown _1215709711.unknown _1215709856.unknown _1173207870 propagation mechanisms for surface initiated cracking in composite pavements al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 5, no. 3, pp 51 59 (2009) propagation mechanisms for surface initiated cracking in composite pavements zainab ahmed alkaissi* duraid ali al khafagy** department of civil engineering/ university of al-mustansiriya * email: zainabalkaisi77@yahoo.com ** email: djeeran2005@yahoo.com (received 3 february 2009; accepted 2 june 2009) abstract: the primary objective of this study was to identify the mechanisms for the development and propagation of longitudinal cracks that initiate at the surface of composite pavement. in this study the finite element program ansys version (5.4) was used and the model worked out using this program has the ability to analyze a composite pavement structure of different layer properties. also, the aim of this study was modeling and analyzing of the composite pavement structure with the physical presence of crack induced in concrete underlying layer. the results obtained indicates that increasing the thickness of the asphalt layer tends to decrease the stress intensity factor, which may be attributed to the rapidly decrease of horizontal tensile stress in the asphalt layer. the cracks initiate at the surface due to high vertical stress and shear stress from wheel loads tends to propagate downward due tensile stress generated at the bottom of the asphalt layer or near crack tip, and the whole process occur at the same location of the existing cracks in underlying concrete layer rather than travel up from existing crack. as the load position varies from the crack zone, this result in tensile stresses or tension at the crack tip, leading to increase the stress intensity factor and intern result in crack propagation further into the depth of the pavement. key words: finite element; pavement model; crack propagation; composite pavement; stress intensity factor; stress distribution; crack initiation; horizontal tensile stress. 1. introduction cracking of road pavements is one of a major source of distress in roadways. a model that is able to simulate the initiation and propagation of cracks in asphalt layer is highly desirable. it will provide an insight into these distress mechanisms and help improve mechanistic design procedure for cracks. the primary objective of this study was to identify the mechanisms for the development and propagation of longitudinal cracks that initiate at the surface of bituminous pavements. also investigate the stress state (horizontal tensile stress and vertical stress within composite pavement structure), and how affect on the direction of crack propagation. moreover, the aim of this study was modeling and analyzing of composite pavement structure with the physical presence of crack induced in concrete base layer, which result in the critical condition for top-down crack propagation. 2. literature review for cracking problems, a natural solution would be to use fracture mechanics (anderson, 1995). the single parameter could be either stress intensity factor k ( or equivalency energy release g) or j integral, depending on the size scale of the yielding of the material: the basis for the use of this approach is that the stress and strain field in the small zone ahead of the crack tip (called fracture zone , or fpz) in which fracture occurs is controlled by a signal parameter, the stress intensity factor (canga et. al.,2001). mailto:zainabalkaisi77@yahoo.com mailto:djeeran2005@yahoo.com zainab ahmed alkaissi al-khwarizmi engineering journal, vol. 5, no. 3, pp 51 -59 (2009) 52 the traditional fatigue approach and the distortion energy approach both implement analysis of a homogeneous continuum pavement. the distortion energy approach is being used by some researchers (kim et.al., 1997). the fatigue life of asphalt mixtures under cyclic loading conditions was found from relationship between pseudo-stiffness and number of loading cycles. the damage mechanics model can then predict damage growth for local load conditions with different loading rates and rest periods; however, in reality, it attempts to simulate the conditions for a cracked pavement. the physical presence of the crack is omitted, and the stress redistributions that result from crack growth are not captured. definition of the traditional fatigue approach to pavement evaluation has been cited in some publications (huang, 1993; yoder and witzak, 1975). the existing approach to performance prediction is broad and classifies pavement failure types that have been studied several times. the theories reviewed included the traditional fatigue approach, distortion energy approach, damage mechanics and fracture mechanics. although it would possible to use any of the methods examined for predicting failure, it was determined that the combination of using finite element modeling and fracture mechanics was most appropriate for best analysis the behavior of crack growth and critical conditions at crack tip (collop and cebon,1995). analysis of cracked asphalt pavement has been studied using the abaqus finite element computer program and show that the mechanism of crack failure was tension. also the load position and base stiffness for flexible pavement affect on crack propagation and confirmed observation of crack growth in the field (leslie et. al., 2001). 3. description of finite element model for composite pavement structure the finite element numerical analysis allows for physical representation of cracks and discontinuities in pavement structure. in this study the finite element program ansys version (5.4) was used. the model worked out using this program has the ability to analyze a composite pavement structure of different layer properties. a typical schematic of composite pavement structure is shown in figure (1) was analyzed to investigate the possible mechanisms of cracking initiation and propagation. the entire composite pavement system (i.e., asphalt layer, old concrete layer, base and subgrade) was modeled, loaded with measured contact stresses and analyzed for pavement response. the input material properties for composite pavement layers are shown in table(1). fig. 1. schematic representation of composite pavement structure. subgrade subbase concrete base asphalt reflection crack (2.54-15.24) cm 15-25 cm 20 cm 30 cm zainab ahmed alkaissi al-khwarizmi engineering journal, vol. 5, no. 3, pp 51 -59 (2009) 53 table 1, input material parameters for composite pavement layers. parameters layers asphalt layer concrete layer base layer subgrade layer  0.35 0.2 0.35 0.4 c(kpa) 158 16.8 9.2 5.7 1  (degree) 26.3 10 30 25 the analysis procedure was repeated for each time of different loading position, asphalt layer thickness and crack length. also, to represent the reflective cracking in composite pavement a crack have been induced by applying a space gap in concrete in the underlying concrete layer equal to crack length to investigate the effect of reflection crack that appears at top pavement surface. a plane 42, 2-d structural solid has been adopted in this research. the element can be used as a plane element (plane strain or plane stress) or as an axisymmetric element. the element is defined by four nodes having two degrees of freedom at each node, translations and the nodal x and y directions. the element has plasticity, and large strain capability. 4. results and discussions the structural model and the finite element mesh of composite pavement is described in figure (6) to investigate the possible mechanisms of cracking in asphalt layer taking into consideration the effect of pavement structure and load spectra. generation of finite element mesh and defining load ,boundary conditions as shown in figure (6). it preferable to use finite element in places were high stress or strain gradients are expected, therefore the mesh consists of fine mesh close loaded area and at the layers interface, the left and right vertical boundary are constrained to move only in vertical direction whereas those on bottom boundary are all fixed, the rest of the nodal point including those on surface are unconstrained as shown in figure (6). the load case studied is a rectangular domain representation with uniform distribution within the rectangular. for uniform stress distribution analysis, a contact radius of .136 m (5.35 inch) is assumed for a single tire. the radius is based on 80 kn (18 kip) single axle load with a contact pressure of 690 kpa (100 psi). computing strains, stresses displacement and stress intensity factor and finally converted the obtained results into graphical outputs for ease understanding and discussions as shown in next section. a comprehensive parametric study was conducted to determine the effects of load spectra (magnitude and position) and pavement structure on crack propagation. different thickness values for the asphalt layer are considered, ranging from lightly trafficked to heavily trafficked pavement (1-6) inch (2.54-15.24) cm. the results of stress and stress intensity factor are obtained using the ansys version (5.4) finite element computer program. figure (2) shows the variation of stress intensity factor with the thickness of asphalt layer for top and bottom of asphalt layer. the shape of curve for top is similar to that at bottom of asphalt layer, and the only difference is that the stress intensity factor for bottom crack is less than the surface crack. increasing the thickness of asphalt layer tend to decrease the stress intensity factor. this can be attributed to the rapidly decrease of horizontal tensile stress in the asphalt layer as shown in figure (3). and the initiation of cracks is due to high vertical stress applied due to wheel traffic loading at the asphalt surface layer. this is confirmed with results obtained for vertical and horizontal stress distribution in the whole structure of pavement as shown in figure (4) and (5) respectively. zainab ahmed alkaissi al-khwarizmi engineering journal, vol. 5, no. 3, pp 51 -59 (2009) 54 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18 thickness of asphalt layer (m) 0.0 0.5 1.0 1.5 2.0 s tr e s s i n te n s it y f a c to r ( m p a ) bottom of asphalt layer top asphalt layer fig. 2. variation of stress intensity factor with thickness of the asphalt layer. 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 thickness of asphalt layer (m) 40 50 60 70 80 90 100 110 h o r iz o n ta l t e n s il e s tr e s s a t b o tt o m o f a s p h a lt l a y e r ( k p a ) fig. 3. effect of thickness on horizontal tensile stress at bottom of the asphalt layer. fig. 4. vertical stress distribution within pavement structure. finite element analysis of the cracked pavement was conducted to define the critical design conditions at which crack growth will occur. a finite element mesh of the cracked pavement was modeled by induced a gap spacing for crack length at the concrete base layer to simulate the composite pavement structure as shown in figure (6). figure (7) shows the stress intensity factor at pavement surface as a function of crack length already exist in the concrete base layer of the composite pavement. it can be noticed that the increase in crack length result in higher stress intensity factor at the surface of pavement which result in a reflection cracks that appears and exhibit on most composite pavement. also this can be seen in figure (8) which shows the stress zainab ahmed alkaissi al-khwarizmi engineering journal, vol. 5, no. 3, pp 51 -59 (2009) 55 intensity factor for whole pavement structure. this confirmed the generation of cracks at surface and propagates downward. it may concluded that cracks are initiated at surface due to high vertical and shear wheel stress applied then tend to propagate downward due tensile stress generated at the bottom of asphalt layer. fig. 5. horizontal stress distribution within pavement structure. fig. 6. finite element mesh induced crack in the underlying concrete layer. zainab ahmed alkaissi al-khwarizmi engineering journal, vol. 5, no. 3, pp 51 -59 (2009) 56 fig. 7. variation of stress intensity factor at pavement surface with crack length. fig. 8. variation of stress intensity factor within pavement structure. also it can be concluded that reflection cracks initiate and propagate at the same location of the existing cracks in underlying concrete layer since its represent the weak zone in pavement structure rather than travel up from down crack. to study the effect of load spectra, different load positions are considered in this study, which they are important factors to induce critical stress and strain. the finite element model was analyzed at four different loading positions as shown in figure (9), relative to crack location (tire’s widest rib over crack, 25, 40, 50, and 70) cm and the obtained results for stress intensity factor are shown in figure (10). it can be seen from figure that intensity factor increases with radial distance from load positions, which can be attributed to the horizontal tensile stresses that generated near the crack zone as shown in figure (11). as the load position varies from the crack, this results in tensile stresses or tension at the crack tip, leading 4 6 8 10 12 14 16 18 20 22 crack length (cm) 0.50 1.00 1.50 2.00 s tr es s in te n si ty f a ct o r (m p a ) zainab ahmed alkaissi al-khwarizmi engineering journal, vol. 5, no. 3, pp 51 -59 (2009) 57 to increase the stress intensity factor and intern result in crack propagation further into the depth of pavement. and throughout the asphalt layer depth, the crack propagate straight down into the pavement by tension then after the direction or crack propagation change due to stress state change with depth. fig. 9. finite element mesh induced crack in the underlying concrete layer for different loading positions. fig. 10. variation of stress intensity factor with loading position. 0 10 20 30 40 50 60 70 80 local positioning from center line of wheel loading (cm) 0.80 0.85 0.90 0.95 1.00 1.05 s tr es s in te n si ty f a ct o r (m p a ) zainab ahmed alkaissi al-khwarizmi engineering journal, vol. 5, no. 3, pp 51 -59 (2009) 58 fig. 11. horizontal stress distribution within pavement structure (local positioning from center of loading 50 cm). 5. conclusions the main concluding remarks can be summarized as follows: 1. increasing the thickness of the asphalt layer tends to decrease the stress intensity factor. which may be attributed to the rapidly decrease of horizontal tensile stress in the asphalt layer. and the stress intensity factor for bottom crack is less than the surface crack. 2. the generation of cracks at the surface and propagate downward. it’s initiate at surface due to high vertical and shear wheel stress applied then tend to propagate downward due tensile stress generated at the bottom of asphalt layer or near crack tip. also the crack initiate and propagate at the same location of the existing cracks in underlying concrete layer rather than travel up from down crack. 3. as the load position varies from the crack zone, this result in tensile stresses or tension at the crack tip, leading to increase the stress intensity factor and intern result in crack propagation further into the depth of the pavemen 6. references [1] anderson, t. (1995): “fracture mechanics”, crc press, and 2nd edition. [2] ."ansys manual", version (5.4), usa, 1996. [3] canga, m. , becker, e., and ozupek, s. (2001): “constitutive modeling of viscoelastic materials with damage computational aspects”. computer methods in applied mechanics and engineering, vol.190, pp: 15-17. [4] collop, a and cebon, d. (1995): “a theoretical analysis of fatigue cracking in flexible pavements”. proceedings, institution of mechanical engineers, vol. 209, pp. 345361. [5] huang, h.y. (1993): “ pavement analysis and design ”. prentice-hall, englewood cliffs, new jersey. [6] yoder, e. and witczak, m. (1975): “principles of pavement design ”. john wiley and sons, new york. [7] kim, y. r., lee, h., and little, d. (1997): “fatigue characterization of asphalt concrete using viscoelasticity and continuum damage theory”. journal of the association of asphalt paving technologists, vol.66, pp.520-569. [8] leslie, a., reynaldo, r. and bjorn, b. (2001): “propagation mechanisms for surface initiated longitudinal wheel path cracks ”. paper presented at the 80 th annual meeting, trb, washington, d.c, usa, january 2001, 01-0433. 59 51، صفحة 3، العذد 5مجلة الخوارزمي الهنذسية المجلذ زينب احمذ القيسي (200 9) 59 ميكانيكية انتشار الشقوق في التبليط المركب دريذ علي الخفاجي * زينب احمذ القيسي انجايعح انًسرُظزٚح/ كهٛح انُٓذسح / لسى انُٓذسح انًذَٛح * الخالصة فٙ ْذِ انذراسح ذى . اٌ انٓذف االساسٙ يٍ ْذِ انذراسح ْٕ نرعٍٛٛ انًٛكاَٛكٛح نرٕنذ ٔاَرشار انشمٕق انطٕنٛح انرٙ ذُشا فٙ سطح انرثهٛظ انًزكة انٓذف يٍ ْذِ انذراسح كاٌ عًم . انذ٘ نّ انماتهٛح عهٗ ذحهٛم ذزكٛة انرثهٛظ انًزكة تاخرالف خٕاص طثماذansysّاسرخذاو تزَاج انعُاطز انًحذدج اٌ انُرائج انرٙ ذى انحظٕل عهٛٓا ذضًُد اٌ سٚادج سًك طثمح . يٕدٚم ذحهٛهٙ نرزكٛة انرثهٛظ انًزكة يع ٔجٕد أ اَشاء شك فٙ طثمح انكَٕكزٚد انرحرٛح اٌ انشمٕق ذُشا فٙ سطح انرثهٛظ َرٛجح االجٓاداخ . االسفهد ٕٚد٘ انٗ َمظاٌ يعايم شذج االجٓاد ٔانذ٘ ٚعشٖ انٗ َمظاٌ اجٓاداخ انشذ فٙ طثمح االسفهد انعًٕدٚح ٔاجٓاداخ انمض انكثٛزج انًرٕنذج يٍ احًال انعجهح انًسهطح ثى ذسرًز اسفم تسثة اجٓاداخ انشذ انًرٕنذج اسفم طثمح االسفهد أ تمزب حاف انشك اٚضا . ٔاٌ ْذِ انعًهٛح ذحذز تُفس يكاٌ انشك انمذٚى انًٕجٕد فٙ انطثمح انكَٕكزٚرح انرحرٛح تعكس يا ْٕ يعزٔف تاٌ انشمٕق ذسرًز يٍ االسفم انٗ االعهٗ اخرالف يٕلع انحًم يع يُطمح انشمٕق ٚسثة اجٓاداخ شذ فٙ حافح انشك ٔٚؤد٘ انٗ سٚادج يعايم شذج االجٓاد ٔتذٔرِ ٚسثة اسرًزار ذٕنذ انشمٕق فٗ عًك .انرثهٛظ investigation of generalized correlation and predictions of reidual enthalpy of superheated vapor for pure components al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 5, no. 3, pp 60 71 (2009) corrosion and galvanic behavior of copper, carbon steel and zinc couples in (3.5 %wt) nacl solution jamal m. ali qasim m. abbas department of chemical engineering /university of technology email: jmal_ali2003@yahoo.com / p.o.box:35010 (received 27 january 2009; accepted 7 september 2009) abstract the galvanic corrosion of the (cu fe), (cu zn) and (fe zn) couples have been investigated in 3.5% nacl solution, 40ºc, different velocities (re = 5000, 10000 and 15000) and different area ratio’s of cathode to anode (ar= 0.5,1 and 2), by using commercial metal pipe (cylindrical tube).the zero resistance ammeter has been used to measure the galvanic current (ig) and galvanic potential (eg) with time. the galvanic current density increases with increasing velocity (re) and the area ratio (ar). the galvanic potential (eg) is shifted to less negative with increasing velocity (re) and the area ratio (ar). a statistical relations for the galvanic current density and galvanic potential as a function of (re). and the area ratio had been created depending on quasi-newton method. there is good agreement between experimental and predicted results. keywords: corrosion behavior in copper, galvanic corrosion 1. introduction galvanic corrosion is the corrosion that results when two dissimilar metals with different potentials are placed in electrical contact in an electrolyte. a difference in electrical potential exists between the different metals and serves as the driving force for electrical current flow through the corrodant or electrolyte. this current result in corrosion of one of the metals. the larger the potential difference, the greater the probability of galvanic corrosion. galvanic corrosion only causes deterioration of one of the metals. the less resistant, active metal (high potential) becomes the anodic corrosion site. the stronger, more noble metal is cathodic and protected. if there were no electrical contact, the two metals would be uniformly attacked by the corrosive medium as if the other metal were absent. two locations susceptible to galvanic corrosion are a piping transition from one metal to another and a sacrificial anode (such as zinc) [1] .galvanic corrosion is a simple concept of electrical potential and electron transfer. three components are needed to enable the action of a galvanic cell: 1. dissimilar metals with differing electrical potentials. 2. a common electrolyte, a conductive solution or any solution that will conduct electricity. 3. an electronic connection or metals in direct contact that will enable the transfer of electrons from one metal to the other. altering the system can eliminate or reduce the harmful effects of galvanic corrosion [2] . many factors including the electrochemical ones determine whether or not galvanic corrosion will occur, as: area ratio (ar), distance apart in the galvanic series, mass transport, distance effect, alloy composition, bulk solution properties and reaction kinetics. pryor [3] investigated the galvanic corrosion of al/steel couple in solution containing chloride and found that aluminum completely protects steel cathodically within the ph range 0-14; the galvanic current and the corrosion rate of aluminum are at a minimum in the nearly neutral ph range. jamal m. ali al-khwarizmi engineering journal, vol. 5, no. 3, pp 60 71 (2009) 61 mansfeld [4] investigated the effect of variation in area ratio of two metals in a galvanic couple in which three common cases of corrosion of galvanic couples have been treated. in case 1, it was assumed that the galvanic potential would be in a region where only significant process on the more active metal is dissolution. on the other hand the only significant process on the more noble metal is reduction of oxidizer. in this case, a measurement of the galvanic current density will give an exact value or the dissolution rate of the anode. in case 2, it was assumed that coupling of more active metal to more noble metal causes only such a small shift of the potential of more active metal that a cathodic as well as an anodic process takes place at significant rates on more active metal and tafel behavior is therefore not observed. in this case, the galvanic current density is always smaller than the dissolution current density of the anode. it is assumed that the corrosion rate of more active metal is controlled by the diffusion rate of the oxidizer (o2) to the surface of more active metal, and more noble metal metal is acting as an oxygen electrode. mansfeld et al. [5] investigated the effect of area ratio on the galvanic corrosion and found that the galvanic current density a gi with respect to the anode is directly proportional to the area ratio, ac aa 1 ka g i  …. (1) mansfeld [6] studied the instrumentation for measurement of galvanic current as a function of velocity of metal / electrolyte and found that the relationship between galvanic current density and velocity is:  vconst.const. g i  …. (2) tsujino et al. [7] studied the galvanic corrosion of steel coupled to noble metals (pt, cu, 304 stainless steel), in sodium chloride solution and found that the local currents on the steel depend on the area ratio of the steel to the cathodic metal and these currents are not related to the concentration of sodium chloride(0.5 – 4)%wt. in neutral solutions. budinski et al. [8] predicted the electrochemical criterion for the development of galvanic coating alloys for steel in air saturated nacl solution and found that when galvanically coupled to steel in 5wt. % nacl, zinc effectively protects the steel against corrosion. the corrosion rate of zinc, however, is very high. the cathodic protection potential determined for steel in 5wt% nacl was – 0.725 v, vs.sce for a corrosion rate of less than 1 mpy. kullter [9] describes the galvanic corrosion of carbon steel and its interaction with coating material such as aluminum, cadmium and zinc, found that extremely slow degradation of aluminum and cadmium, however, can be expected in salt spray, while zinc coatings experienced the highest corrosion attack. wilhelm [10] work was conducted to quantify the magnitude of galvanic currents and potentials that exist between metals (iron, copper, titanium, aluminum, chromium and nickel) and their corrosion products in oxygen containing environments, and found that oxide films on metals that arise because of passivation in aqueous environments or that develop from thermal treatment during processing provide a galvanic couple to the metal substrate. the magnitude of the galvanic interaction may be deduced by consideration of the electronic properties and thickness of the films. olsson et al. [11] investigated the galvanic action in heat exchangers working with seawater as cooling medium and found that presence of sand, h2s, co2 and nh3 accelerates localized attacks on copper based alloys. venugopalan et al. [12] investigated the galvanic corrosion in ti-6a-4v/ co-cr-mo alloy, and found that the galvanic corrosion tests can be used to evaluate new surface modification that may enhance the performance of the alloy couple electrochemically. stephen [13] studied the galvanic action in zinc alloys, and found that the corrosion of the anodic metal is both more rapid and more damaging as the voltage difference increases and as the cathode area increases relative to the anode area. wilhelm [14] studied galvanic corrosion between dissimilar materials using laboratory simulation of oil/gas production environments. galvanic corrosion of materials used in production equipment (9cr, 13cr, n/c42, sm2550, betacti, and c-276) was studied in corrosive environments, which included sweet well produced fluids, sour well produced fluids, heavy brine packer fluids, and acid zing fluids. corrosion coupons of various geometries were used to measure corrosion rates and morphologies. electrochemical measurements were performed to determine potentials and current densities. the experimental study found jamal m. ali al-khwarizmi engineering journal, vol. 5, no. 3, pp 60 71 (2009) 62 that the severity of galvanic attack is a strong function of the type of corrosion products that come from a metal surface. 2. experimental work throughout this investigation the corrosion of carbon steel , zinc and copper materials in coupled conditions (galvanic action) was studied in 3.5% sodium chloride solution under different flow conditions at constant temperature (40˚c ± 0.5). one kind of electrochemical measurement was conducted, galvanic current and galvanic potential measurements. the specimens have inside diameter of (2.6cm), length (2.4cm) and outside diameter of (2.8cm) and were used as received. the test section was mounted horizontally and preceded by (50cm) entrance region (i.e. l/d=10) of q.v.f. tube to ensure fully developed flow condition before the solution reaching the specimens [15, 16]. the test section was followed by (35cm) exit length to avoid disturbance at the outlet [17, 18] . fig. 1. experimental apparatus. the effect of velocity [re = 5000, 10000 and 15000] and different area ratios [ar = 0.5, 1 and 2] of cathode to anode for different galvanic couples (cu-fe), (cu-zn) and (fe-zn) were thoroughly investigated. the flow system was designed to contain the items as mentioned in fig.(1). in the galvanic measurements, the two test sections are composed of the following components: working electrode (cathode); (cu, fe), working electrode (anode);(zn, fe), reference electrode;(sce)and zero resistance ammeters (zra). (zra) is a device used to measure the galvanic current (ig) and galvanic potential (eg), which was first simply constructed by mansfeld et al. [19] . this was measured using digital millivoltmeter. the galvanic current was calculated from potential measurement. experimental procedure, for coupled metals, the galvanic corrosion current generated between the two metals and galvanic potential was measured at the same time. each test was performed twice and if repeatability was in doubt a third test was carried out. 3. results and discussion the results presented in figs. (2) through (4) which show clearly the behaviors of galvanic current density (ig) and galvanic potential (eg) with time for area ratio of (0.5, 1and 2) and fig. (1)experimental apparatus. jamal m. ali al-khwarizmi engineering journal, vol. 5, no. 3, pp 60 71 (2009) 63 reynolds number of (5000, 10000 and 15000) at steady state. (e.g. for re=5000 and ar=0.5, (cufe) couple, steady state galvanic current density (ig) and galvanic potential (eg) and after 4 hours was (0.956a/m 2 ,-646.948mv)). fig. 2. time behavior of galvanic current density and couple potential (cu-fe) couple, (re= 5000, 10000 and 15000) and ar=0.5. fig. 3. time behavior of galvanic current density and couple potential (cu-zn) couple, (re= 5000, 10000 and 15000) and ar =1. jamal m. ali al-khwarizmi engineering journal, vol. 5, no. 3, pp 60 71 (2009) 64 fig. 4. time behavior of galvanic current density and couple potential (fe-zn) couple, (re= 5000, 10000 and 15000) and ar =2. the initial galvanic current density is maximum value and decreases slowly until steady state galvanic current is reached. this maximum value is apparently dependent on the (ar and re). because the metal surfaces at the beginning of the test were clean and active for corrosion to ensure but during a later stage corrosion product film will be formed which will decrease the activity of the metal surfaces and impede the diffusion of oxygen. this was noticed with time as the electrolyte colour changed due to formation of corrosion products. this time behavior which is in accordance with what were noticed by others [20, 21, 22] .the galvanic potential (eg) is changed with time to more negative values, where the (eg) is recorded at each minute for an experimental run of four hours long. precisely the galvanic potential (eg) became rapidly more negative in the first (30-45) min., and then the curve converged to slower rate, that is because of the formation of the oh ions at a high rate and grouping on the electrodes [23]. 3.1. reynolds number effect from figs. (2) through (4), it is clear the value of the galvanic current density (ig) increases and galvanic potential (eg) is shifted to a less negative value with increasing re. this is due to the increase in the amount of oxygen transport to the surface, via increasing eddy diffusion. as a consequence of increasing the (ig) the galvanic potential is shifted to more positive. the relationship between galvanic potential and area ratio shows that increasing area ratio increases the galvanic potential in the more noble direction as shown in fig.(5) for different flow conditions. this is due to the increased influence in the more noble metal. the average galvanic current density (ig) was determined graphically by calculating the area under the curve from the galvanic current-time curve. a suitable equation has been created by using grapher package program. integration applied to each equation, integral current time for (0-240min.) time interval, has been calculated for each case. the average values of galvanic current density are listed in tables (1) to (3). jamal m. ali al-khwarizmi engineering journal, vol. 5, no. 3, pp 60 71 (2009) 65 fig. 5. the area ratio effect on the galvanic potential for (cu-fe), (cu-zn) and (fe-zn) couples at different re. table 1, average galvanic current density of (cu-fe) couple under different flow conditions and area ratios. area ratio (cu-fe)couple galvanic current (a/m 2 ) re = 5000 re = 10000 re = 15000 0.5 1.147 1.599 1.794 1 1.653 2.115 2.478 2 2.315 2.796 3.361 table 2, average galvanic current density of (cu-zn) couple under different flow conditions and area ratios. area ratio (cu-zn)couple galvanic current (a/m 2 ) re = 5000 re = 10000 re = 15000 0.5 1.804 2.242 2.475 1 2.152 2.619 3.105 2 2.93 3.645 3.741 table 3, average galvanic current density of (fe-zn) couple under different flow conditions and area ratios. area ratio (fe-zn)couple galvanic current (a/m 2 ) re = 5000 re = 10000 re = 15000 0.5 2.401 2.762 3.277 1 2.811 3.443 4.062 2 3.501 4.411 4.712 jamal m. ali al-khwarizmi engineering journal, vol. 5, no. 3, pp 60 71 (2009) 66 the relationship between galvanic current density (ig)) and flow rate (re.) is shown in fig.(6) for different area ratio of the cathode to anode. the galvanic current density increases with increasing reynolds number and area ratio. as the area ratio increases, the influence of reynolds number becomes more significant as shown at area ratio of 2, a linear relationship is shown between log ig and log re, which is in agreement with what was found by others [21, 24]. fig. 6. effect of re on the galvanic current density for (cu-fe), (cu-zn) and (fe-zn) couples at different ar in 3.5% nacl solution at 40 ºc. 3.2. area ratio effect galvanic current density (ig) increases with increasing area ratio (ar) while galvanic potential moves in the noble direction due to increasing corrosion current with increasing cathodic area. area ratio plays an important role in galvanic corrosion as it was found from the results. it plays a comprehensive role as shown in figs. (2) to (4) and tables (1) to (3) which show that increase in area ratio (ac/aa) increases (ig). increasing area ratio leads to increase in the exposed area to corrosive solution, i.e. the more negative electrode will corrode and the more positive electrode is protected. the total surface area is equal to the summation of the anode surface area and cathode surface area as shown in table (4). table 4, relationship between area ratio and surface total area (at). ar (ac /aa ) ac (cm 2 ) aa (cm 2 ) at = ac+aa (cm 2 ) 0.5 8.1681 16.3363 24.5044 1 16.3363 16.3363 32.6726 2 32.6726 16.3363 49.0089 jamal m. ali al-khwarizmi engineering journal, vol. 5, no. 3, pp 60 71 (2009) 67 one can notice from this table that the total area of metals (at) increases with increasing area ratio which leads to increase in average galvanic current (ig (av.)) as shown in tables (1) to (3). in this study, the effect of area ratio of the cathode to anode on the galvanic current is clearly shown in fig.(7) which show increasing galvanic current with increasing ar for given re. these findings are advocating the results previously noticed by tsujino and miyase [7]. fig. 7. the relationship between galvanic current density and area ratio for (cu fe), (cu zn) and (fe zn) couple. fig. 8. behaviour of a metal couple fe-zn, ar>>1 produces galvanic attack of zn (schematic) [24]. consider the situation in fig.(8) where the area ratio f1/f2 is very large, i.e. the noble metal (fe) greatly exceeds by one the active metal (zn) in area. the total anodic and cathodic current curves of fig.(8) have been constructed by summing the currents f1i1 and f2i2 according to the eq.(3) [24]: itotal= f1i1 + f2i2 …. (3) clearly, in the absence of fe, the corrosion of the active metal zn would be represented by the (ē, f2i΄). if the noble metal fe is also present the overall corrosion situation is represented by the point of intersection of the two total curves at p. at the potential ecouple, the corrosion current of zn is f2i˝, so that zn is now corroding at a current density of i˝ as against i ́shown previously. the intensity of attack on the active metal is greatly enhanced (in the ratio i˝ / i΄) when the metal is coupled to a large area of a more noble metal fe. in fig.(8) the distribution of the various anodic and cathodic reactions is schematically represented. zn corrodes rapidly (thick arrow) and most of the electrons generated are fed into fe where cathodic reaction occurs almost jamal m. ali al-khwarizmi engineering journal, vol. 5, no. 3, pp 60 71 (2009) 68 exclusively. zn is said to undergo galvanic attack [24]. fig. 9. behaviour of a metal couple fe-zn, ar>>1 produces galvanic attack of zn (schematic) [24]. where f1/f2 is very small, i.e. the active metal (zn) greatly exceeds the noble metal (fe) by one in area; the situation is represented in fig.(9). again, the total anodic and cathodic curves have been constructed and they can be seen in fig.(9) these intersect at q, where the potential ecouple has now moved in the active direction relative to p in fig.(8). in these circumstances the presence of fe makes very little difference to zn. however, the interest should be directed to fe. it may be seen that, where zn is not present, corrosion of fe would normally take place at a potential ē and current f1i΄. but because the potential of the couple (viz. at q) is now below the reversible potential efe, corrosion of fe now ceases altogether because there can be no net anodic reaction at the fe׀ fe ++ interface. as a result, fe is said to be galvanically protected. fig.(9) shows the distribution of reaction [25] .this is also the situation for the (cu-fe) couple and (cu-zn) couple where cu is totally protected. 3.3. statistical relationships the data obtained from monitoring the galvanic current density and galvanic potential with time as shown in previously in figs. (2) through (4), are presented mathematically by a regression analysis to give: ig = a + b (re) +d (ar). …. (4) eg = a + b (re) +d (ar). …. (5) where: ig = galvanic current density (a/m 2 ) at steady state. re = reynolds number. eg = galvanic potential (mv) at steady state. ar =area ratio. these equations have been created depending on “quasi newton method”, which are included in statistical program package. the mathematical expression for different couples are shown in table (5). the comparison between the measured galvanic current and potential with predicted values by the relations in the table (5) show a good agreement between them as shown in table (6). from statistical point of view they are absolutely accepted, (i.e., c.c=0.9 – 1). table 5, the mathematical expression for different couples couple the relations c.c mean error (%) cu-fe ig = 0.144167 +0.000075(re) + 0.773571(ar) eg = -665.988+0.001167 (re) +35.96557 (ar) 0.989 5.255 0.978 2.51 cu-zn ig = 0.470167 +0.000086(re) +0.672048(ar) eg = -1067.8+0.002975(re) +34.95643(ar) 0.988 1.55 0.989 9.845 fe-zn ig =0.746833-0.000103(re) +0.965952(ar) eg = -1038.85+0.002242(re) +178.7616(ar) 0.974 3.72 0.999 1 jamal m. ali al-khwarizmi engineering journal, vol. 5, no. 3, pp 60 71 (2009) 69 4. conclusions from present study the following points can be concluded: 1. copper is a good cathode, carbon steel and zinc worked as efficient sacrificial anodes in the environment of 3.5% nacl solution at 40 o c and a variable reynolds number. 2. galvanic current density (ig) for different couples (cu-fe, cu-zn and fe-zn) increases with increasing reynolds number and area ratio of metals. 3. galvanic potential for different couples (cufe, cu-zn and fe-zn) is less negative with increasing reynolds number and area ratio. 4. area ratio plays an important role in increasing the galvanic attack in most of the cases. 5. mathematical expressions for galvanic potential and galvanic current density as a function of re and ar for the various couples give good agreement between the predicted and calculated values. table 6, a comparison between predicted and experimental values of galvanic corrosion and galvanic potential of different couples in 3.5 nacl solution and 40c ο , under different flow conditions and area ratio. re.no. area ratio galvanic potential (eg),”mv” experimental predicted cu-fe cu-zn fe-zn cu-fe cu-zn fe-zn 5000 10000 15000 0.5 -646.95 -641.34 -634.03 -1038.3 -1024.4 -1007.02 -945.05 -932.15 -924.85 -642.2 -636.3 -630.5 -1035.5 -1020.6 -1005.7 -938.3 -927.03 -915.84 5000 10000 15000 1.0 -618.03 -610.14 -606.9 -1016.9 -996.42 -983.95 -837.16 -825.4 -819.12 -624.2 -618.4 -612.5 -1017.9 -1003.1 -988.2 -848.9 -837.7 -826.5 5000 10000 15000 2.0 -590.22 -584.34 -579.25 -983.96 -965.54 -958.93 -675.28 -665.64 -646.27 -588.2 -582.4 -576.6 -983.01 -968.14 -933.26 -670.1 -658.9 -647.7 table 6, continue re.no. area ratio galvanic current (ig),”a/m 2 ” experimental predicted cu-fe cu-zn fe-zn cu-fe cu-zn fe-zn 5000 10000 15000 0.5 1.147 1.599 1.794 1.804 2.242 2.475 2.401 2.762 3.277 0.907 1.283 1.659 1.235 1.664 2.093 1.745 2.260 2.775 5000 10000 15000 1.0 1.653 2.115 2.478 2.152 2.619 3.105 2.811 3.443 4.062 1.294 1.670 2.046 1.571 2.000 2.429 2.228 2.743 3.258 5000 10000 15000 2.0 2.315 2.796 3.361 2.930 3.645 3.741 3.501 4.411 4.712 2.067 2.444 2.820 2.243 2.672 3.101 3.194 3.709 4.224 jamal m. ali al-khwarizmi engineering journal, vol. 5, no. 3, pp 60 71 (2009) 70 5. references [1] forms of corrosion, an internet site of kennedy space center of http://www.tpub.com/content/dueeds.htm. , (2001). [2] galvanic corrosion, pall mabee -wah chang, article given on the internet at the web site http://www.out looku24n2.com,(2003). [3] pryor, m.j., corrosion j., no.1, vol. 14, p.1, (1958). [4] mansfeld, f., corrosion j.,no. 10, vol.27 , p.(436442),(1971). [5] mansfeld,f.and kenkel,j.v.,corrosionsciencej.,no. 1,v.15,p.239(1975). [6] mansfeld, f., corrosion j., no.9, vol.32, p.(380.381),(1976). [7] tsujino, b.,and miyase,corrosion j.,no.4,vol.38,p.(226-230),(1982). [8] budinski, m.k.andwilde, b.e., corrosionj.,no.1,vol.43,p.(60-62), (1987). [9] kullter, w., corrosion science j., no.2, vol.28, p.(173-198),(1988). [10] wilhelm, s.m., astm stp 979, p.(2334) , (1988). [11] olsson, a.o. and newman, m.b., chemical engineering world j., no.11, at http://www.exicom.org/cew,(1997). [12] venugopulan, r., justice, t.a., lucas, i.c. and lemons, j.e., an internet article, (2000). [13] stephen, c.d., article given on the internet at the web site http://www.ocean.udel.edu, (2002). [14] wilhelm s.m., corrosion, no.48, vol.8, p.(691-703) aug. (1992). [15] bennett, c. o. and myers, j. e., momentum, heat and mass transfer, 3 rd ed., mc graw hill, united states, (1982). [16] ozisk,m.n.,heat transfer, 3 rd ed., mcgraw hill, new york,(1988). [17] postlethwaite, j.,fiadzigbe,e.,s.,corrosion j.vol.34,no.3, p. 85,(1978). [18] al-auasi,b.,o., ph.d.thesis, university of al-nahrain , (2003). [19] mansfeld,f., and lauer,g., corrosion j.no.11, vol.26,p.504, (1970). [20] mansfeld,f.and kenkel,j.v.,corrosion science j.,no.11,vol.15,(1975). [21] ali,j.m., m.sc. thesis, university of baghdad, (1990). [22] al-kelaby,s.s.b., ph.d.thesis, university of al-nahrain , (2007). [23] faulkner l.l., s.b.menkes,corrosion and corrosion protection handbook, marcel dekker, (1983). [24] west, j. m., electrodeposition and corrosion processes, van nostrand reinhold company, 2 nd ed.,(1971). [25] steigerwald, r. f., corrosion, no.24,p. 1, (1968). 71 60، صفحة 3، العذد 5هجلة الخىارزهي الهنذسية الوجلذ جوال هانع علي (200 9) 71 التأكل والتصرف الغلفاني لوسدوجات النحاش،الحذيذ والسنك في هحلىل كلىريذ %(wt 3.5)الصىديىم بتركيس قاسن هحوذ عباش جوال هانع علي اٌداِعح اٌرىٌٕٛٛخيٗ /لسُ إٌٙذسح اٌىيّياٚيح 35010. ب.ص/ اٌعشاق/ تغذاد الخالصة عٕذ % 3.5في ِحٍٛي وٍٛسيذ اٌصٛديَٛ تٕسثح , (cu-fe(,)cu-zn(,)fe-zn)ذُ دساسح اٌرأوً اٌىٍفأي إٌاذح ِٓ أسرخذاَ ِزدٚخاخ اٌّعادْ ٚوأد , (ar=0.5,1.0,2.0)ٚتأخرالف ٔسثح ِساحح اٌىاثٛداٌى االٔٛد (re=5000,10000,15000)ٚتحاالخ خشياْ ِخرٍفح , ο 40َدسخح حشاسج ٌمياس اٌرأوً اٌىٍفأي إٌاذح ِٓ ستط ِعذٔيٓ عٍى شىً ,(zero resistance ammeter)ٚذُ اسرخذاَ .إٌّارج اٌّسرخذِح عٍى اٌشىً االسطٛأي االٔثٛتي . ِزدٚج ٚوزٌه لياس خٙذ اٌرأوً اٌىٍفأي ِع اٌزِٓ تيّٕا خٙذ اٌرأوً اٌىٍفأي يز٘ة ,(ar)ٚٔسثح اٌّساحح (.re)ِٓ خالي اٌرداسب اٌّدشاج ٌٛحظ اْ اٌرأوً اٌىٍفأي يزداد تزيادج سشعح اٌدشياْ . تأالذداٖ االلً ساٌثا تزيادج اٌسشعح ٚٔسثح اٌّساحح ٚٔسثح اٌّساحح ٚتاالعرّاد عٍى اٌطشق (.re)ذُ اسرٕراج عاللاخ سياضيح ذشتط تيٓ اٌرأوً اٌىٍفأي ٚتيٓ اٌدٙذ اٌىٍفأي ِع اٌسشعح ِرّثٍح ب . ٚواْ ٕ٘ان ذطاتك ٚاضح تيٓ إٌرائح اٌعٍّيح ٚإٌظشيح اٌّسرٕردح,(statistica)اٌعذديح ٚتأسرخذاَ اٌثشٔاِح االحصائي 57 al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 4, no. 4, pp 57-70 (2008) the effect of additives on the performance of hydrostatic thrust bearings albert e. yousif and muhammed abdul sattar department of mechanical engineering/ college of engineering/ nahrain university (received 26 september 2007; accepted 13 april 2008) abstract the paper is concerned with, the behavior of the hydrostatic thrust bearings lubricated with liquid-solid lubricants using einstein viscosity formula, and taking into account the centrifugal force resulting from high speed. also studied is the effect of the bearing dimensions on the pressure, flow rate, load capacity, shear stress, power consumption and stiffness. the theoretical results show an increase in load capacity by (8.3%) in the presence of solid graphite particles with concentration of (16%) by weight as compared with pure oil, with increasing shear stress. . in general the performance of hydrostatic thrust bearings improve for load carrying capacity, volume flow rate, pumping power subjected to centrifugal parameter (s), recess position (r1), film thickness ratio (), particle concentration (). keywords: thrust bearings and liquid solid lubricant. 1. introduction: hydrostatic thrust bearings are finding an increasing use in a wide variety of applications, particularly in machine tools, aerospace industries and large pumps used in pumping storage projects [1]. the fluid or lubricant may be a gas, in the case of pressurized gas bearing but in general high viscosity fluids are used such as oils and water. in recent years many workers studied the effect of contaminants and or polymeric solutions that increase the viscosity index of the lubricant. in the theory of lubrication, it has been shown that the influence of the inertia terms on the equations of motion is negligible, as compared with effect of the viscous terms, when the reynolds number re << 1. brand [2] carried out an order of magnitude analysis of the equation of motion in thrust bearings. he showed that when re = 1, the inertia and viscous terms are equally important in predicting the performance characteristics of thrust bearings.. it has been shown by several workers [3-7] that centrifugal forces for bodies of polar symmetry have a significant effect and should be retained in the equations of motions. the classical theory of hydrostatic lubrication assumes that the lubricant behaves as a newtonian viscous fluid (shear rate varies linearly with the shear stress). however, non-newtonian characteristics have been in variably observed in various processes. this may be due to the high shear rates and the high pressure gradient, or may be due to additives such as solid lubricants mainly, molybdenum disulfide mos2 and graphite. therefore, the linear relationship between the shear stress and the shear rate is not valid for non-newtonian behavior. 2. theoretical analysis: a circular step thrust bearing is shown in figure (1) oil from an externally pressurized source is fed to the bearing either through an orifice or a capillary restrictor. the radius of the recess is often appreciable. it enables the static supply pressure to separate the bearing surface. albert e. yousif al-khwarizmi engineering journal, vol.4, no.4, pp 57-70 (2008) 58 dowson [3] assumed that for such bearings the pressure at the lubricant supply hole extends to the step. he also confirmed the validity of the assumption. the theoretical results of dowson [3] were experimentally corroborated by coombs and dowson [8], especially at low speeds. an approximate expression for the pressure distribution was obtained using the “energy integral method”. the validity of applying an energy integral approach was justified by kapur and verma [9] who demonstrated the agreement between theoretical and experimental results for magnetohydro-dynamic thrust bearing and squeeze film bearings respectively. the solid fraction of powder particles contained within base oil is usually taken by weight. this is more acceptable from the physical point of view einstein equation which takes the following form:    ..(. 5.21* c where c, represents the volume concentration of the particles, * and  are the viscosity of the suspension and the pure oil, respectively. furthermore, the constant c, was replaced by a3 in the work of yousif and hassan [10], where a3 is postulated by:     ... //11/13  pa where,  is the percentage of the particles by weight. p and  are the densities of solid particles and oil respectively. referring to equ. (2), it can be appreciated that the final form of einstein formula is a more realistic form than that equation (1) since it deals with the weight rather than volume percentage. in this paper, the analysis was based on the flow with einstein’s equation as special case in viscosity function:   )3...(    where    5.21 3a 3. governing equations: for the externally pressurized circular pad bearing illustrated schematically in fig.(1) after applying the previous assumptions, the momentum equations can be expressed as follows, taking the centrifugal forces in to account . fig.1. thrust hydrostatic circular step bearing.        2 22 z u r p r v       0 2 2 z v      0 z p where the variation in pressure in the z-direction is negligible and the equation of continuity is:         0 1 z w r ru r the simplified momentum equations, in dimensionless form, reduce to:           1 4 4 2 22 z uk z u r p r vs         0 4 4 2 2 z v k z v     0 z p and the equation of continuity is:       0 z w r u r u r r  h w 2 ro region   region  z r  albert e. yousif al-khwarizmi engineering journal, vol.4, no.4, pp 57-70 (2008) 59 where k = /*r2 ,  = pr/* , rprs 22  the volume flow rate q can be evaluated from the integral   2 0 h zdurq   the velocity distribution without centrifugal effects, by integrating equ.(9) and applying boundary conditions that the radial velocity on the upper and lower surfaces of the bearing, satisfy equ. (12) is obtained as: the boundary conditions are: u =0 at z =0 u =0 at hz  …(14) 0 2 2    z u at z =0 0 2    z u at hz  the velocity v can be found by integrating equ. (10) twice, subject to the boundary conditions that, 0v at 0z rv  at hz  …(15) 0 2 2    z v at hz ,0 thus, it can be shown that:  h zr v  4. pressure distribution: the radial pressure gradient is obtained from equation (9) by applying an energy integral approach [9]. multiplying equation (9) by u and integrating the resulting expression can be obtain as follows:        )17...( 1 2 2 00 2 0 dz z u uzdvu r s zdu r p hhh                  rhf q r hfh hsf r p 1 11 2 2     where     6 3 2 h hf        20 5 2 h hf    for a bearing of the form shown in fig.1 expressions for the pressure distribution on the either side of the step are required. the pressure distribution takes the forms: for region i (recess) fig.1 : 1rrr            1 1 2 1 2 2 ln 2 cr hf q r hfh hsf p        where c1 is constants of integration. the boundary conditions are: 1p at rr  and hh  hence,                        r r hf q rr hfh hsf p ln 2 1 1 22 1 2 2     …(19) for region ii (land) fig.1: 11  rr           2 1 2 1 2 2 ln 2 cr hf q r hfh hsf p     where c2 is constant of integration. the boundary conditions are: 0p at 1r and hh  hence,           )20...(ln1 2 1 2 1 2 2    r hf q r hfh hsf p  5. lubricant flow rate: assuming pressure continuity at the step, then from equations(18) and (20)the dimensionless flow rate is obtained as: albert e. yousif al-khwarizmi engineering journal, vol.4, no.4, pp 57-70 (2008) 60                      )21...( ln ln 1 22 1 1 1 1 1 2 1 1 2 2 1 2 22 12                                       hf r r hf r r hfh hf hfh rrhf s q   6. load-carrying capacity: the dimensionless load-carrying capacity w , of the bearing considered above, can be calculated as:   22 1 2 1 1 r r r rdprrdprrw   hence, the result is expressed as:  21 2 wwrw  where 1w and 2w are the load capacities in the regions of recess ( 1rrr  ) and (land) ( 11  rr ) respectively, such that:                                               hfh rhsfrhsf hqh r r qhfh rw    1 22 2 2 2 12 221 1 2 2 11 2 2ln44 4 1           )24...( 2 4 1 1 2 2 2 2 22            hfh rhsfhq rr                 )25...( . ln42 . 22 4 1 1 2 2 1 2 1 2 12 1 2 22 12 4 1 2 2 2                   hfh hrqrrhsf hfh hqrhsfrhqhsf w 7. bearing power consumption: there are two contributions to bearing power losses: 1. the power lost due to pad rotation. 2. losses due to pumping the lubricant through the bearing clearance. the power loss due to pad rotation is obtained as follows. if the bearing components move relative to each other the frictional resistance to such motion is due to the force required to shear the lubricant. the shear stress for this case is: hzz v           * when the expression for the tangential velocity (v) given in equ. (14) is used, the frictional drag on an element of area (2rdr) is given by: )26...( 2  drrdf  or )27...( 2 2 *  dr h r df    and the frictional torque on the element is: d= r.df or dr h r d    3 *2 the frictional torque  is obtained by integrating the elemental torque over the bearing area: )28...(2 1 1 33 *            r r r r dr h r dr h r    the frictional power pf is defined as: pf== )29...( 2 4 1 444 1 2*                     h rr h rr    the pumping power required to operate the bearing can be expressed as: pp=q.ps …(30) the power factor is: )31...( 2  w q h f albert e. yousif al-khwarizmi engineering journal, vol.4, no.4, pp 57-70 (2008) 61 8. stiffness: the bearing stiffness can be expressed )32...( 2  dh dkp wpr s the flow through the restrictor can be written in a general form as:   )33...( 1  n p n s q qi kphkq where kq, q and n are the compensator flow constants. using equs. (21) and (33) and differentiation of the resulting equation with respect to h one gets:                                         1 1 1 2 p pn p s q p p k nk k dh dk k k dh dk where pskkq    )35...( /lnln 1 20 3 1 6 3 31 1 2 3                         h r r r rs rp k s s      the stiffness per unit supply pressure (ss) is defined in dimensionless form as: )36...( ap h s s s  9. results and discussion: results are presented in terms of dimensionless pressure distribution p , load carrying capacity w , flow rate q , stiffness per unit supply pressure ss, shear stress w , centrifugal parameter s, solid particle concentration . the viscosity for pure oil at atmospheric pressure  spao .04.0 sae 30 at 50 co, density of the oil ( = 850 kg/m 3 ), table (1) shows type of solid particle since the non-newtonian behavior of the liquid solid lubricant is attributed to the existence of these solid particles where (co) uniaxial compressive strength (n/m 2 ). table 1 properties of the most common solid lubricants solid lubricant co (n/m 2 ) ep (n/m 2 ) p (kg/m 3 ) p mos2 3.2e10 2.8e9 4800 0.31 carbon graphite 2.7e10 2.8e8 1730 0.3 teflon 7e8 2.8e8 2160 0.3 the bearing radial direction is divided into two main parts, the first region is in the recess  1rrro  and second region is in the land  11  rr to study the simultaneous influence of solid particle concentration  and centrifugal parameter s on the performance of hydrostatic thrust bearing. fig. (2)-(5) show the variation at different positions for various values of the parameters such as solid particle concentration , centrifugal parameter s, film thickness ratio , couple stress parameter , and recess radius 1r . fig. (2) and fig. (3) represent the theoretical pressure distribution increasing with increase the centrifugal parameter s when increase rotating speed () and film thickness ratio () because of increase in pocket pressure for pure oil. these results is in agreement with dowson’s[3]. albert e. yousif al-khwarizmi engineering journal, vol.4, no.4, pp 57-70 (2008) 62 fig. 2. effect of centrifugal parameter (s) on the pressure distribution for pure oil. fig.3. effect of the film thickness ratio () on the pressure distribution for pure oil. fig. (4) represent effect of increasing the recess radius 1r over the pressure distribution for pure oil because of increase in pocket area. fig. (5) shows the pressure minus, if recess is less than 0.3, a negative pressure region will appear on the bearing land and cavitation may occur, for increasing rotating speed  has a beneficial effect on the pressure distribution if  3.01 r , but it is deleterious if  3.01 r because the negative pressure region in the bearing land increases with increasing rotating speed  which may lead to cavitation. fig. 4. effect of the recess radius (r1 ) on the pressure distribution for pure oil. fig. 5. effect of the solid concentration () on the pressure distribution to avoid minus pressure. in this work the results of additives of solid particle (lubricant with contaminant) we can avoid cavitation this case is shown in figure (5) when increasing concentration of solid particle  the pressure negative reduced. the pressure gradient changes sign at a point along the flow where the viscous and inertia forces are equal. the position of this point depends on , ,  and 1r . 0.0 0.2 0.4 0.6 0.8 1.0 r 0.0 0.4 0.8 1.2 p s = 4 s = 2 s = 0 r = 0.05 r = 0.51  0.0 0.2 0.4 0.6 0.8 1.0 r 0.0 0.4 0.8 p   s = 0 r = 0.05 r = 0.5 1 0.0 0.2 0.4 0.6 0.8 1.0 r 0.0 0.4 0.8 1.2 p r = 0.3 r = 0.4 r = 0.5 1 1 1 s = 0 r = 0.05  0.0 0.2 0.4 0.6 0.8 1.0 r 0.0 0.4 0.8 1.2 p graphite by weight pure oil = 16 s = 4 r = 0.05 r = 0.2 = 5 1 albert e. yousif al-khwarizmi engineering journal, vol.4, no.4, pp 57-70 (2008) 63 fig. 6. effect of the concentration of solid particles () on the pressure distribution in the absence of the hole of radius ro. fig.7. effect the concentration of solid particles () on the pressure distribution. fig.(6) and fig. (7) represent the concentration of solid particle  effect on the pressure distribution without effect of the hole radius or . this result shows increase in the recess region and land region by using boundary condition in recess, when the pressure is constant see [15], but in this research boundary condition involves the hole radius or . hence, the pressure at this case can be represented in fig. (7). fig. (8) represents the effect of solid particle concentration  on the pressure distribution of the three types of solid particle used, graphite has higher effect than mos2 and teflon. the increase in density of the addition the viscosity for mixture increases by effect on the formula   . fig. 8. effect of the type of solid concentration particle () on the pressure distribution. fig. 9. effect the concentration of solid particles () on the pressure distribution. 0.0 0.2 0.4 0.6 0.8 1.0 r 0.0 0.4 0.8 1.2 p      graphite by weight 0.0 0.2 0.4 0.6 0.8 1.0 r 0.0 0.4 0.8 1.2 p grapgite      s = 0 r = 0.05 r = 0.5   1 0.0 0.2 0.4 0.6 0.8 1.0 r 0.0 0.4 0.8 1.2 p  pure oil graphite teflone mos2 s = 0 r = 0.05 r = 0.5  1 0.0 0.2 0.4 0.6 0.8 1.0 r 0.0 0.4 0.8 1.2 p      graphite by weight s = 2 r =0.05 r =0.5  1 albert e. yousif al-khwarizmi engineering journal, vol.4, no.4, pp 57-70 (2008) 64 fig. 10. effect the concentration of solid particles () on the pressure distribution. fig. (9) and fig. (10) show the pressure distribution increasing with increase solid particle concentration  with (s=0, s=2, s=4) and 5.01 r . 9.1. volume flow rates ( q ): fig. 11. variation of the flow rate (q) with centrifugal parameter (s) and film thickness ratio (). fig. (11) shows that the flow rates q increases with increasing centrifugal parameter s and film thickness ratio . fig. (12) shows the effect of solid particle concentration  for graphite and mos2 and recess radius 1r . the flow increases with increase of recess radius 1r because of increase in pocket area and decreases with increasing solid particle concentration  because of increase in viscosity. fig. 12. variation in flow rate (q) with recess position (r1). fig. 13. variation in flow rate (q) withthe of solid particle concentration (). 0.0 0.2 0.4 0.6 0.8 1.0 r 0.0 0.4 0.8 1.2 p      s = 4 r = 0.05 r = 0.51   0 2 4 6 8 10 s 0 2 4 6 q   10 -10 0.0 0.2 0.4 0.6 0.8 1.0 r 0 20 40 60 80 q 1 graphite     10 -10 s = 0 r = 0.05  0 4 8 12  2.0 2.5 3.0 3.5 4.0 4.5 q s = 4 s = 0 mos2 graphite pure oil s = 2 10 -10 albert e. yousif al-khwarizmi engineering journal, vol.4, no.4, pp 57-70 (2008) 65 fig. (13) shows variation of flow rate q with solid particle concentration  for graphite and mos2, flow rate q decreases with increasing solid particle concentration . 9.2. load carrying capacity (w ): fig. (14) shows the variation of load carrying w with recess radius 1r and centrifugal parameter s. load carrying w increases with increase recess radius 1r and centrifugal parameter s. these results are similar to those reported by dowson [3] where the classical viscous fluid theory (pure oil) was used. fig.14. effect of recess radius ratio ( 1r ) andcentrifugal parameter (s) on the load factor( w ). fig.(15) shows that increasing load capacity increases with increasing solid particle concentration , load carrying capacity is higher for graphite than for teflon and mos2 because of increasing in viscosity. fig. (16) shows increase in load capacity with increase in solid particle concentration and recess radius because of increase in pocket area by increase recess radius. load carrying capacity increase by 8.3% for solid particle concentration of 16% graphite by weight as compared with pure oil. when using couple stresses fluid load carrying capacity increased by 9.7% for solid particle concentration of 16% graphite by weight as compared with pure oil. fig.15. variation of the load factor ( w ) with three type of solid particle concentration (). fig.16. effect of recess radius ratio ( 1r ) and concentration of solid particle () on the load factor (w). 9.3. power factor ( ph ): fig. (17) shows the effect of recess radius 1r and centrifugal parameter s on the power factor ph for pure oil. it can be stated that as 1r increases from 0.05 to 0.9, power factor ph 0.0 0.4 0.8 1.2 r 0.0 0.2 0.4 0.6 0.8 1.0 w s = 4 s = 2 s = 0 1 r = 0.05   0 4 8 12 16  0.60 0.62 0.64 0.66 w by weight graphite teflone mos2 pure oil r = 0.05 r = 0.5 s = 0   1 0.0 0.4 0.8 1.2 r 0.0 0.2 0.4 0.6 0.8 w 1          r s = 0 albert e. yousif al-khwarizmi engineering journal, vol.4, no.4, pp 57-70 (2008) 66 decreases until it reaches a minimum value at certain 1r and then ph increases as 1r increases. the value of 1r at which ph is a minimum depends on s, i.e. as s increases from 2 to 4. the value of 1r at minimum ph increases. it is also clear that as s increases from 0 to 2, ph decreases and as s increases from 2 to 4, ph may increase or decrease depending on the value of 1r . the results are in agreement with those khalil and ismail [15]. fig.17. effect of recess radius ratio ( 1r ) and centrifugal parameter (s) on the power factor(hp). fig. 18. effect of recess radius ratio ( 1r ) and solid particle concentration () on the power factor (hp). fig. (18) shows the effect of concentration of the solid particle  (graphite by weight) on the power factor ph . it is clear that the power factor ph decreases when solid particle concentration  increases with recess radius 1r (0.05 to 1). 9.4. stiffness per unit supply pressure ( ss ): fig. (19) shows the effect of compensation (orifice and capillary) and recess radius 1r on the stiffness per unit supply pressure ss . the ratios pk and  are taken as 0.5 and 5 respectively. it is clear that as recess radius 1r increases from 0.05 to 0.9 stiffness factor ss increases. however, the orifice compensation is stiffer than the capillary compensation. fig. 19. effect of recess radius ratio ( 1r ) on the stiffness factor (ss) for (capillary and orifice) compensation. fig. (20) shows the effect of the solid particle concentration , the ratio pk varying from 0.1 to 0.9 and with values of  take 5, the recess radius 1r is taken as 0.6. it clear that ss increases with increasing solid particle concentration  .graphite increases the stiffness per unit supply pressure ss more than mos2 because of its higher density, 0.0 0.4 0.8 r 1 10 100 1000 10000 h s = 4 s = 2 s = 0 1 10 -10 r = 0.05  p 0.0 0.4 0.8 r 1 10 100 1000 h 1 graphite by weight       r = 0.05 s = 0  p 0.0 0.2 0.4 0.6 0.8 1.0 r 0 10 20 30 s s 1 capillary m=1; kq=0.3 oriffice m=0.5; kq=0.1 s = 0 r = 0.05 ps = 60e6 kp = 0.5  albert e. yousif al-khwarizmi engineering journal, vol.4, no.4, pp 57-70 (2008) 67 hence causing an increase in the viscosity of the mixture. fig.20. effect of the solid particle concentration () and pressure ratio (kp) on the stiffness factor (ss). fig.21. effect of film thickness ratio () on the stiffness factor (ss). fig. (21) shows the effect of film thickness ratio  on the stiffness factor ss , recess radius 1r has range from 0.1 to 0.9, the ratio kp takes 0.5. it is clear that ss increases when  increases for capillary compensation. fig. (22) shows the effect of the centrifugal parameter s on the stiffness factor ss . it is clear that when centrifugal parameters s increases stiffness factor ss increases because of increasing rotating speed , hence increase load carrying capacity. fig. 22. effect of centrifugal parameter (s) on the stiffness factor (ss). 9.5. frictional power fp: fig. (23) show the frictional power fp variation with different values of film h and fig. (24) show solid particle concentration  effect on the frictional power fp. the frictional power decreases with film thickness h and increases with increase in solid particle concentration  because of increase in viscosity. fig. 23. effect of solid particle concentration () on the frictional power (fp) (=0.04pa.s, =5, r1=0.5m, =100rpm, r=1m). 0.0 0.2 0.4 0.6 0.8 1.0 kp 0 1 2 3 4 5 s s pure oil = 16 graphite = 16 mos2 s = 0 r = 0.05 r = 0.6 ps = 60e6 1  0.0 0.2 0.4 0.6 0.8 1.0 r 0 2 4 6 8 10 s s 1 capillary    s = 0 r = 0.05 kp = 0.5 ps = 60e6 m = 1 kq=0.3 0.0 0.2 0.4 0.6 0.8 1.0 r 0 4 8 12 16 s s capillary s = 0 s = 2 s = 4 r = 0.05 m=1 kp=0.5 kq=0.3 ps=60e6 1  0.5 1.0 1.5 2.0 2.5 3.0 h ( mm ) 0 2 4 6 f p ( k w ) graphite by weight   pure oil albert e. yousif al-khwarizmi engineering journal, vol.4, no.4, pp 57-70 (2008) 68 fig.24. effect of solid particle concentration () on the frictional power (=0.04pa.s, =5, r1=0.5m, =100rpm, r=1m). fig.(25) shows the frictional power fp increases with increase in recess radius 1r . fig. 25. effect of recess radius ( 1r ) on the frictional power (fp) (=0.04pa.s, =5, =100rpm, ro=0.05m, r=1m). fig. (26) shows the effect of rotating speed  on the frictional power factor fp, it increases with increase in rotating speed . fig.26. effect of rotating speed () on the frictional power (fp) (=0.04pa.s, =5, r1=0.5m, ro=0.05m, r=1m). 9.6. shear stress ( w ): fig.(27) shows the effect of solid particle concentration  on shear stress w , it is clear that shear stress w increases with increase in solid particle concentration. fig.27. effect of solid particle concentration () on the shear stress ( w ). 0.5 1.0 1.5 2.0 2.5 3.0 h ( mm ) 0 2 4 6 f p ( k w ) = 16 by weight graphite mos2 pure oil 0.5 1.0 1.5 2.0 2.5 3.0 h ( mm ) 0 1 2 3 4 5 f p ( k w ) r = 0.3 r = 0.5 r = 0.7 1 1 1 0.5 1.0 1.5 2.0 2.5 3.0 h ( mm ) 0 2 4 6 8 10 f p ( k w ) = 50 rpm = 100 rpm = 150 rpm 0.0 0.2 0.4 0.6 0.8 1.0 r 0 1 2 3 t w graphite by weight    10 -4 albert e. yousif al-khwarizmi engineering journal, vol.4, no.4, pp 57-70 (2008) 69 10. nomenclatures: r outside radius of bearing r / r dimensionless radial radius 1r r1 / r dimensionless radius of step or ro / r dimensionless hole radius z z / r dimensionless axial coordinate h h / r dimensionless film thickness  film thickness ratio  angular speed rev/min ps supply pressure p p/ pr dimensionless pressure * equivalent viscosity of the two-phase lubricant o viscosity for pure oil c volume concentration of the particles p particle density o oil density  weight concentration of solid particle  () new viscosity function for einstein formula s =  2 r2 / pr centrifugal parameter q =  q /  r3 pr dimensionless volumetric flow rate w = w/  r2 pr dimensionless load capacity m, q, kq compensator flow constant kp = pr / ps ratio between inlet pressure and supply pressure 11. references: [1] .a. christ and m. peron. 1980, “ hydrostatic thrust bearing for storage pumps,” escherwyss news, vol. 53 pp. 71. [2] r. s. brand, 1956, journal of applied mechanic, vol.77 pp. 363. [3] dowson, d., 1961, “inertia effects in hydrostatic thrust bearings,” asme, journal of basic engineering, vol. 83 pp. 227. [4] c. chung, moon and d. w. darcing. 1976, “ the contribution of fluid film inertia to the thermohydrodynamic lubrication of sector pad thrust bearings,” asme journal of lubrication technology, vol.98, pp. [5] o. pinkus and j. w. land, 1981” centrifugal effects in thrust bearings and seals under laminar conditions,” asme journal of lubrication technology, vol. 103, pp. 126136. [6] r. s. gupta and v. k. kapur, 1982, wear, vol.77 pp. 203. [7] s. safar. 1983, “ centrifugal effects in misaligned hydrostatic thrust bearings,” asme journal of lubrication technology, vol.105 pp. 621. [8] coombs, j. a. dowson, d., 1965 “an experimental investigation of the effect of lubrication inertia in hydrostatic thrust bearing,” 3rd lub. and wear conv. proc. ime, london, u, k. vol. 179 part 3j, p. 96. [9] v. k. kapur and k. verma, (1975) “ energy integral approach for hydrostatic thrust bearing,” asme journal of lubrication technology vol.97 n.4 pp.697. [10] yousif, a. e., and nacy, s. m., 1981 “ hydrodynamic behavior of two-phase (liquid-solid) lubricants,” wear, vol. 66, no. 2, pp.223-240. [11] yousif, a. e., and hassan, k. j., 1985 “the lubrication of journal bearings with two-phase (liquid-solid) lubricants,” proc. of the jsme int’ l trib. conf. tokyo, pp. 1121-1126. [12] khalil, m. f. and ismail, a. s., “performance characteristics of externally pressurized bearings under turbulent flow conditions,” sited from ref [6]. [13] osterele, j. f, and huges, w. f., 1961” inertia induced cavitation in hydrostatic in hydrostatic thrust bearings,” wear, vol. 4 pp. 228. [14] khalil, m. f ismail, a.s. (1989) “centrifugal effects in externally pressurized bearings under turbulent flow conditions,” tribology international vol.22 n.4 pp. 265-272. (2008 )70-57، صفحة 4، العذد 4 مجلة الخوارزمي الهنذسية المجلذ البرت يوسف نعمان 70 تأثير االضافات على سلوك المحامل محمذ عبذ الستار محمذ البرت يوسف نعمان جاٍؼت اىْهشيِ /مييت اىهْذست / قسٌ اىهْذست اىَيناّينيت الخالصة بأضافت اىجسيَاث اىصيبت اىخي حْثش (صيب-سائو)في هزا اىبحث حٌ دساست سيىك اىَحاٍو اىهيذسوسخاحينيت راث ٍضيخاث ثْائيت اىطىس ٍغ اىضيج اىْقي بخشميض وصّي ٍؼيِ ورىل باسخخذاً ٍؼادىت ايْشخايِ اىَطىسة ىيضوجت ، ٍغ االخز بْظش االػخباس حأثيش اىقىة اىطاسدة (حخيط) اىضغط، ٍؼذه اىجشياُ، سؼت اىخحَيو، )مَا حَج دساست حأثيش االبؼاد اىهْذسيت ىيَحَو ػيى . اىَشمضيت اىْاحجت ٍِ دوساُ اىَحَو بسشع ػاىيت . (اجهاداث اىقص، اىطاقت اىالصٍت واىصالبت ىجسيَاث اىجشافيج باىَقاسّت ٍغ (%16)ػْذ ّسبت اىخشميض اىىصّيت ( %8,3)ىىحظ ٍِ خاله اىْخائج اىْظشيت صيادة في اىحَو بَقذاس .وصيادة في اجهاد اىقص (صيج ّقي)اىحَو في حاىت ػذً وجىد اىجسيَاث اىصيبت microsoft word ????34-42 al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 17, no. 1, march, (2021) p. p. 3442 hurst exponent and tsallis entropy markers for epileptic detection from children sumai hamad jaafer erbil medical institute/ erbil polytechnic email: sumaya.hamad@epu.edu.iq (received 2 august 2020; accepted 23 november 2020) https://doi.org/10.22153/kej.2021.11.001 abstract the aim of the present study was to distinguish between healthy children and those with epilepsy by electroencephalography (eeg). two biomarkers including hurst exponents (h) and tsallis entropy (te) were used to investigate the background activity of eeg of 10 healthy children and 10 with epilepsy. eeg artifacts were removed using savitzky-golay (sg) filter. as it hypothesize, there was a significant changes in irregularity and complexity in epileptic eeg in comparison with healthy control subjects using t-test (p< 0.05). the increasing in complexity changes were observed in h and te results of epileptic subjects make them suggested eeg biomarker associated with epilepsy and a reliable tool for detection and identification of this disease in children. generally, this study aims to provide an evident of a reliable biomarker to detect epilepsy in children to give them an additional chance to live a high quality life. keywords: detection, electroencephalography, entropy, epilepsy, savitzky-golay, t-test. 1. introduction epilepsy is a very common and old neurological disease, with around 50 million patients around the world 80% of them in the developing countries [1]. the clinical detection of the epilepsy depends on the history of the family beside a thoroughly analysis of the eeg test for abnormal changes. epilepsy, according to the international league against epilepsy (ilae), is a brain disorder in which there is continuous propensity to start an epileptic seizures and by the cognitive, neurobiological, social, and psychological consequences of this condition. it is required to have one epileptic seizure to consider the case as epileptic subject, this seizure leads to a temporal disorders and symptoms occurs on the brain due to excessive, abnormal, and hypersynchronous neural discharge activity in the brain, which can cause brain dysfunctional, the word came from greek meaning to take hold [2]. patients with epilepsy may suffer from cognitive problems such as stigma, exclusion, restrictions, overprotection, and isolation, which also become part of the epileptic condition. seizures sometimes lead to unexpected death during or after a period of ictus, normally these types of deaths categorized as sudden death, regarding a known clinical cause of death [3], most probably due to asphyxia [4]. epilepsy can originate in different locations and lobes in the brain, normally all located in the brain cortex, for example in [5, 6] the seizures originated in the frontal lobe, most of the mentioned cases where originated from partial seizures. , the studied cases included occurrence of seizures while sleeping, mainly during the rapid eye movement (rem) stage. in [7], a case study of a 18 months old infant, has a seizures in his cerebellar ganglioma, due to the existence of a mass in his left cerebellar hemisphere, which leads to a hemifacial contractions in his left side of his face. temporal lobe epilepsy (tle) is also sumia hamad jaafer al-khwarizmi engineering journal, vol. 17, no. 1, p.p. 3442 (2021) 35 a recorded cases and had been studied over women on reproductive intervals [8]. epilepsy is a significant neurological disorder that is identified by recurrent spontaneous partial or generalized seizures. it is estimated that the proportion of the global population with active epilepsy is between 4 and 10 per 1000 people. this proportion is getting higher and higher in developing countries and can reach 6 to 10 per 1000 people. epileptic seizures vary from shortterm twitches to prolonged and severe convulsions they could happen at any age as well as at different levels of severity. even though there is progress in the types of available epilepsy treatment, about 30-40% of epilepsy patients fail to respond to antiepileptic drugs or other types of interventions. taking into consideration that even patients who respond to the available epilepsy treatments may encounter complications and medical issues such as depression, it is important to understand the complex mechanisms and factors that may influence on epilepsy. this understanding could lead to novel treatments that would modify its generation/progression and eventually control or reduce seizures in epilepsy patients, thus avoiding at least some of the medical complications associated with current available treatment. electroencephalogram (eeg) is a very stochastic, non-stationary and highly complex signal that has been widely used to detect epilepsy. eeg signals with such a nature makes it difficult to be analyzed using normal clinical inspection or time domain techniques [9]. automated detection of epilepsy is done by making a clear distinguishing between ictal and interictal intervals of an epileptic eeg signal, in this manner a reliable epileptic detector will be available, which can perform an online detection of the recorded eeg signal with a perfect diagnosis for the patient. normally the detection of epileptic patients done by clinical inspection and analysis of the eeg recording of each patient, yet this process consumes a lot of time and effort while the needs to shorten the time required due to the increment in the number of patients [10]. another important issue is the accuracy of the clinical test, which require the presence of a professional each time, otherwise will effect on the quality of diagnosis, while the automated detection will ensure a high accuracy and reliable diagnosis each time and in all conditions [11]. the traditional way to detect epileptic spikes is by using eeg recordings through the visual scanning and inspection. however, this technique required long eeg diagnostic time and it is an inaccurate method. to overcome these cons, many automatic methods have been used such as linear time-frequency analysis and non-linear such as largest laypunov exponent (lle) and correlation dimension (cd) [12, 13]. furthermore, several types of eeg measurements have been used due to complexity of the brain and the signal such as approximate entropy (ae) [14], kolmogorov entropy [15], sample entropy [16, 17]. in addition, many available system today such as long term epilepsy, ceeg intensive care unit (icu) monitoring and sleep testing for the most flexible and comprehensive recording system and long legacy. in the current study, the hurst exponents (h) and tsallis entropy (te) have been computed to enhance the epileptic process understanding and to distinguish the children with epilepsy from the control healthy subjects. the t-test has been used to show the reliability of the new methods to measure the complexity-based structure of the brain for children with epilepsy and healthy ones and to find the significant differences among various groups at p ˂ 0.05 significance level. 2. materials and methods figure 1 shows the block diagram of the proposed study. fig. 1. the block diagram of the current study. sumia hamad jaafer al-khwarizmi engineering journal, vol. 17, no. 1, p.p. 3442 (2021) 36 2.1. procedure of recording and acquisition of eeg data eeg data has been obtained by using eeg recording headset (a micromed brain spy plus embia via giotto 2, 31021 mogliano veneto, treviso, italy). two reference electrodes, with 19 electrodes in addition to one ground electrode were used. notably, international system of 10-20 has been applied, thus following arrangement of the eeg electrodes arrangement was performed (fp1, fp2, f7, f3, fz,f4, f8, t3, c3, cz, c4, t5, p3, pz, p4, t6, o1 and o2). importantly, electrode reluctance has been fixed to be below 5 kilo-ohms. eeg dataset of the current study have been obtained by analyzing samples of 20 children, who they are primary school students (10 normal control students, and 10 students with epilepsy). students’ ages were from 6 to 12 years old. controls students had not shown any conditions such as psychiatric or neurological. notably, human ethics committee of the teaching hospital, erbil, iraq has approved all protocols were applied in this experiment. children who are suffering from epilepsy have been chosen from the teaching hospital neurology clinic. finally, all participants in this study signed an information consent form (icf). 2.2. denoising stage previous studies have demonstrated that noise from both extrinsic and intrinsic sources, for example noise resulted from surrounding environment, and noise producing by internal structure of human body have to be eradicated [18-20]. therefore, removing power line interference noise has been performed by using notch filter. consistently, butter worth has been utilized for the second order band pass filter ranging from 0.1 to 60 hz in the first stage [21]. in the second stage, and in order to smooth out the signal with lowest level of destruction of its original features, savitzky–golay (sg) has been utilized. interestingly, shifting effect after filtering the signal has been involved in this approach. one of the important features of sg filter, it offers advantages of preserving features of a time series that includes its relative minima and maxima, which indicate a highly significant concern relating to segmentation of a signal such as eeg [22-25]. it has been reported that in two parameters, the performance of sg filter mainly dependents on the frame size and polynomial order. importantly, following equation has been depended on to fit the coefficients of an sg filter (n=nr+n1+1) points of the eeg signal. so window size described by n, while both signal points in right and signal points in left of a current signal point have been identified by nr and n1 respectively. moreover, it has been reported that set up investigation of sg filter parameters to the 3rd order polynomial and a frame size of 51 samples is essential to de-noise and smooth the eeg dataset [26]. 2.3. features extraction epilepsy is a central nervous system disorder that is accompanied by frequent seizures. eeg is the main recording method that has been used for a long time for seizures events recoding. however, eeg is not very efficient for diagnosing, and classification of different conditions such as normal, predictive, and psychological conditions, which are relatively difficult due to the instability of eeg signals and the length of the recording period. this deficiency of the previously mentioned method required the researchers to try new techniques. in this study, two techniques these are hurst exponents (h) and tsallis entropy (te) were suggested for the detection of epileptic seizures. h was used by kannathal et al. as a chaotic measure, among other techniques, as a measure of signal prediction. the percentage accuracy of these measurements about 90% in detecting epileptic eeg this test is an important indicator of long-term signal recording. the value of the hearst exponent is specified between 0 and 1, and the next deviation in the sign is determined by this value [27]. in other words, the self-similarity and correlation of a signal can be assessed by h. this parameter could also reveal the fractal time series flatness depending on the asymptotic behavior of the rescaled variety of the procedure. the calculation method as follows: …(1) where r/s represents corresponding rescaled range value, r the deviation, minimum and maximum, away from the mean. s is the standard deviation, and t is the sample data [26]. in general, earlier, the entropy is defined as a measure based on information theory to calculate order and disorder in a dynamic system [27-28]. this technique could be preferable in monitoring sumia hamad jaafer al-khwarizmi engineering journal, vol. 17, no. 1, p.p. 3442 (2021) 37 signals disorder because the injured brain has a low entropy compared to random continuous eeg. te considers as a nonextensive statistical mechanics [27]. this technique is perfect as a tool to define long-term memory effects systems, multifractal space-time constraints, or long-range interactions [28]. te has its scaling system could utilize to investigate shortand long-range interactions. thus, the tsallis statistics help differentiate among a range of eeg outcomes such as spikes, bursts, and continuous or fused rhythms. the equation that calculates the value of te is: …(2) where q represents the nonextensivity degree. the te was firstly presented to the generalization of nonextensivity in the thermodynamical sense. however, recently, it gets broader applications, and it is widely applied in biomedical signal processing such ecg analysis and, most recently, eeg .the resent studies postulate that the tsallis statistics deliver additional detailed info compared to the conventional procedures, particularly in spike or burst eeg analysis [28]. recent work shows the accuracy of tsallis entropy of 92.67– 100% in detecting different patterns of eeg signals in various types of problems. furthermore, the problem-solving time for this method is ~0.9 ms, i.e., real-time detection. in order to distinguish between epileptic eeg signals and normal healthy control subjects, two types of entropy have been computed in this study. these types are these are te and h. in order to extract features from the original eeg time series for each 19 channels, 60 seconds, n=15360 samples, concomitant with 6 windows of 10 second length (2560 samples) were used in the current study. furthermore, eegs’ abnormalities of dementia patients have been detected by using entropies. previous researchers have revealed that tsen is non-extensive, it was first introduced by havrda and charvát then examined in details by daróczy [28, 29]. actually, measurement of this entropy completely differs from that measurement by standard boltzman–gibbs–shannon entropy measure. in the same line of thought, the boltzman–gibbs–shannon measure has been widespread to a group of measures that are not necessarily comprehensive. alternatively, they can be either sub-additive or super-additive. furthermore, tsen with parameter have been utilized. thus, a generalized measurement of entropy, due to tsen, can be assessed as mentioned by both [30-31]. the concept is based on the measure of the relative frequencies of different motifs. it has been revealed that hurst exponent (h) could be majorly used to calculate the self-similarity of the time series like eeg [17][32]. 2.4. statistical analysis considering the scalp area of the cerebral cortex, denoised 19 channels from the eeg dataset of ten control (healthy), and ten patient’s children with epilepsy have grouped into been categorized into five groups. consequently, these regions represented frontal channels (seven) (fp1, fp2, f3, f4, f7, f8, and fz), three parietal channels (p3, p4, and pz), both temporal channels (t3 and t5), two occipital channels (o1 and o2), and three central channels (c3, c4, and cz). thereafter, kolmogorov–smirnov test was applied in order to measure normality. on the other hand, levene’s test was used to prove homoscedasticity. therefore, t-test has been performed as a statistical way using spss 23. in all sections the independent variables (iv) were the subject groups (control healthy normal subjects and children with epilepsy) as the first iv and the five scalp regions (frontal, temporal, parietal, occipital and central) as the second iv. whilst, one of the former features was the dependent variable (dv). notably, significance for all statistical tests was set at p ˂ 0.05. 3. results and discussion eeg data were recorded for the healthy control subjects and epileptic children as shown in (figures 2 and 3), respectively. form the visual inspection of the waveforms, the recorded eeg signals were exhibits patterns of normal or abnormal brain electrical activities. abnormal patterns may occur because of seizure effect on the brain. sumia hamad jaafer al-khwarizmi engineering journal, vol. 17, no. 1, p.p. 3442 (2021) 38 fig. 2. the eeg activities for the first control healthy subject. fig. 3. the eeg activities for the first subject with epilepsy. the observation to figure 4 shows that sg filters were smoothed the recorded eeg dataset. there were suppressing for all components of the noise as shown in channel 2 (ch2), blue colored line, compared with the original noisy recorded eeg in red colored line. fig. 4. after using sg filter for ch2 which represent fp2 to denoising. table 1 demonstrates the h and te entropy values for the children with epilepsy and agematch control subjects over the five scalp regions. it can be noted that the h of epileptic children eeg signals is slightly higher than that of normal eeg signals in frontal, temporal and occipital regions. this might resulted from hyper mental activity for epileptic children compare to those with normal brain. as well as due to the high regularity and complexity of the eegs during the epileptic seizure compared to normal eegs. on the other hand, the value of te indicated high enactment in order to distinguish normal subjects from epileptic subjects in comparison to h. interpretation of this might to some extent relative the eeg recording dynamic processes, which much less complex for people with epileptic than for normal ones. interestingly, these observations were in agreement with aforementioned works that eeg complexity would be declined as a result of neurotransmitter deficiency, neuronal death and/or loss of connectivity due to death of nerve cell. notably, recognition between healthy and epileptic subject’s eeg signals have a vital role in relative to clinical relevance. mainly because it provides cooperative outfits for the detection of a seizure onset. hence, the h and te can benefit understand epileptic children and normal ones eegs. sumia hamad jaafer al-khwarizmi engineering journal, vol. 17, no. 1, p.p. 3442 (2021) 39 table 1, the average values (mean ± sd) of eegs for the normal control subjects and epileptic patients over the brain regions. significant group differences are marked with an asterisk. brain lobes subjects te p-value h p-value frontal normal 10.73±0.47 0.05* 0.85±0.04 0.03* abnormal 10.18±1.19 0.05* 0.86±0.07 0.03* temporal normal 10.77±0.36 0.05* 0.85±0.03 0.03* abnormal 10.22±1.09 0.05* 0.86±0.07 0.03* central normal 10.75±0.37 0.05* 0.85±0.03 0.06 abnormal 10.21±1.17 0.05* 0.86±0.06 0.06 parietal normal 10.77±0.34 0.05* 0.85±0.03 0.07 abnormal 10.18±1.19 0.05* 0.86±0.07 0.07 occipital normal 10.73±0.4 0.05* 0.85±0.03 0.03* abnormal 10.18±1.1 0.05* 0.87±0.06 0.03* 4. conclusions in summary, this work was attempted to discernment between children with epilepsy and healthy normal subjects. sg filter has been employed for denoising and smoothing the eeg dataset; and h and te were computed. statistical analysis using t-test has been conducted to characterize the features and to investigate the presented hypothesis that both irregularity and complexity in epileptic eeg. in fact, reducing the complexity in epileptic patients compare to the healthy control mainly derived by te whereas increasing the complexity in epileptic patients compare to the healthy control mainly derived by h. thus, it can be considered that the h and te as essential eeg biomarkers in order to detect and identify irregular seizures for children patients with epilepsy. importantly, eeg could be used as an important indicator for examining the background activity in the documentation of children patients with epilepsy. acknowledgments the author wish to express their gratitude to neurology unit staff from the neurology unit at teaching hospital, erbil, iraq for their assistance in the collecting the eeg brain signals during working for manuscript and provided the neuropsychological assessment for all subjects. 5. references [1] h. m. de boer, m. mula, and j. w. sander, "the global burden and stigma of epilepsy," epilepsy & behavior, vol. 12, pp. 540-546, 2008. 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[32] s. dangel, p. meier, h. moser, s. plibersek, and y. shen, "time series analysis of sleep eeg," computer assisted physics, pp. 93-95, 1999. ) 2021( 3442، صفحة 1، العدد17دجلة الخوارزمي الهندسية المجلم سمية حامد جعفر 42 عالمات هيرست و إنتروبيا تساليس الكتشاف الصرع عند الطفال سمية حمد جعفر اربيل / المعهد التقني الطبي qsumaya.hamad@epu.edu.iالبريد االلكتروني: الخالصة تم استخدام اثنين .(eeg) بالصرع عن طريق تخطيط كهربية الدماغ كان الهدف من هذه الدراسة هو التمييز بين األطفال األصحاء واألطفال المصابين هيرست دعاة ذلك في بما الحيوية المؤشرات تساليس (h) من لـ (te) وانتروبيا الخلفية نشاط في و eeg للتحقيق أصحاء أطفال مصابين ١٠لعشرة كما افترضت ، كان هناك تغيرات كبيرة في عدم انتظام .savitzky-golay (sg) باستخدام مرشح eeg تمت إزالة اثار تخطيط كهربائيه الدماغ .بالصرع لموضوعات te و h لوحظت التغييرات المتزايدة في التعقيد في نتائج .t (p <0.05) األصحاء باستخدام اختبار الصرع مقارنة مع أفراد التحكم eeg وتعقيد لـ الحيوية العالمات لدى األطفال رتب الم eeg الصرع مما جعلهم يقترحون المرض والتعرف عليه للكشف عن هذا بالصرع وأداة موثوقة ، بشكل عام .طة .فير دليل على وجود عالمة بيولوجية موثوقة الكتشاف الصرع لدى األطفال لمنحهم فرصة إضافية لعيش حياة عالية الجودة تهدف هذه الدراسة إلى تو al-khwarizmi engineering journal al-khwarizmi engineering journal, vol.4 , no.1 , pp 1726 (2008 ) minimizing error in robot arm based on design optimization for high stiffness to weight ratio. ahmed abdul hussain ali university of baghdad college of engineering, mech. department (received 8 may 2007; accepted 3 december 2007) abstract: in this work the effect of choosing tri-circular tube section had been addressed to minimize the end effector’s error, a comparison had been made between the tri-tube section and the traditional square cross section for a robot arm, the study shows that for the same weight of square section and tritube section the error may be reduced by about 33%. a program had been built up by the use of mathcad software to calculate the minimum weight of a square section robot arm that could with stand a given pay load and gives a minimum deflection. the second part of the program makes an optimization process for the dimension of the cross section and gives the dimensions of the tri-circular tube cross section that have the same weight of the corresponding square section but with less deflection. key word: robot arm stiffness, flexible manipulator, robot structure analysis, flexible link robot. introduction: the links of serial manipulators are usually over designed in order to be able to support the subsequent links on the chain and the pay load to be manipulated. however, increasing the size of the links unnecessarily requires the use of larger actuators resulting in higher power requirements. optimum robot design has been addressed by many researchers as found in the open literature; shiakolas and koladiye [1] discuss the application and comparison of the evolutionary techniques for optimum design of serial link robot manipulators based on task specifications. the objective function minimizes the required torque for a defined motion subjected to various constraints which considering kinematics, dynamic and structural conditions. the design variables examined are the link parameters and the link cross sectional characteristics, the developed environment was employed in optimizing the design variables for a scara and an articulated 3-dof puma type manipulators. in the work developed by marcus pettersson et al. [2] an optimization problem are formulated to minimize the weight of the gearboxes, by choosing different discrete gear boxes, and changing the lengths of the arms continuously, subjected to a few requirements on acceleration capability reach and pay load capacity. analysis of stiffness of manipulator link can be found in abdel malek, k. and paul, b.[3] where aspects of the structural design of the manipulator arm are presented. prismatic joints of manipulator arm are based upon a cross sectional design of the links that provides a high stiffness to weight ratio compared with a hollow round crosssection. the case that we study in this work is the robot that consists of three arms as shown in fig. (1). where the first arm is vertical and the second and third arm are horizontal this gives the maximum reach (completely stretched out) for the robot arm and will yield the maximum deflection for the robot. ahmed abdul hussain ali al-khwarizmi engineering journal, vol.4 , no. 1 pp 17-26 (2008) 18 prismatic joints: most manipulator link crosssection are either hollow round or hollow rectangular. hollow links provide convenient conduits for electric power and communication cables, hoses, power transmission members, etc. rivin[4] has studied the influence of crosssections on the deflections both in bending and torsion. he had compared hollow square with hollow circular cross sections. rivin states that a square cross section can provide a 69 to 84 percent increase in bending stiffness over a circular hollow cross section with only a 27 percent increase in weight. in this paper a different cross-section is introduced, consisting of three tubes centered on the vertices of an equilateral triangle. this cross section is referred to as a tri-tube configuration the hollow square link will be referred to as a uni-tube configuration, as shown in fig. (2). deflection due to pure bending: links with an open end manipulator are normally modeled as cantilevers. consider a simple cantilever with solid or hollow cross – section as shown in fig.(3).to study the proposed cross –section, we use the following equations for moments of inertia (2nd moment of area) about any diametrical axis through the centroid of area. uni –tube: for the unitube depicted fig.(2,a) the moment of inertia about the neutral axis is tbb bb i tubeuni 2, 12 44    where b, b is the outer and inner sides, respectively for the uni-tube construction, t is the thickness of the uni-tube and the area is 22 bba tubeuni  tri-tube: for the tri-tube depicted in fig.(2,b) the moment of inertia about the neutral axis is       2 22 2244 60sin 3 1 4 2 60sin 3 2 464 3             hdd hddddi tubetri   tdd 2 where d and d are the out side and inside diameters, respectively, for each tube on the equilateral triangle, t is the thickness of each tube in the tri – tube construction. the area of each tube is   tdddda tubetri 2, 4 22   to demonstrate the deflection due to loading, consider the third arm beam depicted in fig.(3,c).          83 1 4 33 3 33 3 3 lqlw ei  gmwa l alg l gm q    , where m is the mass of each arm, m is the mass of the gear box and the mass of the load to be manipulated at the end of the arm, q is the weight per unit length of the beam, w is the load in newton, g is the gravitational acceleration and l is the length of the arm, a is the cross sectional area of the beam,  is the specific density. to get the reactions (force and moment) at the fixed end of the third arm we equate the summation of forces and moment to zero i.e.   33330 lqwffy   33 2 33 3 2 0 lw lq mom the same thing may be said for the second arm (fig.3-b) taking in to account the effect of moment in calculating the deflection i.e.              283 1 3 23 4 22 3 223 2 2 lmolqlwf ei  the reactions at the fixed end will be 32222 fwlqf  32322 2 22 2 2 molflw lq mo  for the first arm (fig.3-a) we assume that the deflection at the free end is due to bending moment only and the effect of compressive loads on the whole deflection is neglected therefore 1 2 11 1 2ei lmo  ahmed abdul hussain ali al-khwarizmi engineering journal, vol.4 , no. 1 pp 17-26 (2008) 19 the total deflection at the end effecter of the robot manipulator arm will be   2 1 2 23  total the sequence of analysis in this work is to calculate the weight of the lightest structure that has a square hollow section and with stand the given loading condition this may be achieved by letting the stress in each arm reaches the maximum allowable stress to avoid failure of the structure, the equation for calculating the stress in the third arm may be written as 12 2/* 4 3 4 3 33 3 bb bmo i ym   by letting the stress equal the allowable stress and assuming the thickness of the tube walls to be 2mm we may found the dimension of the third arm, this had been done by the aid of a program built up using mathcad software. the stress in the second arm may also be calculated in the same way i.e. 12 2/* 4 2 4 2 22 2 bb bmo   the dimension of the first arm fig.(3.a) is calculated by equating the maximum stress induced in it with the maximum allowable, this maximum stress is found by the rankinegorden formula [5] which is a combination of the euler and crushing loads for a strut cer fff 111  for very short strut ef is very large, ef 1 can therefore be neglected and cr ff  , for very long struts ef is very small and ef 1 is very large so that cf 1 can be neglected. thus er ff  . the rankine formula is therefore valid for extreme values of slenderness ratios. it is also found to be fairly accurate for the intermediate values. thus, re – writing the formula in terms of stresses )/(1 111 111 ey y ye ye r ye ye yer yer aaa                 for a strut with one end free and the other fixed 2 2 4 l ie fe   and al ie e 2 2 4    the crushing load on the first arm is 121 wfffc  a fc y  the final stress  1 on the first arm is thus the sum of the direct stress calculated by rankine formula and that due to bending generated by the exerted moment  2mo as was explained in figure (3-a and b)   1 12 1 2/* /! i bmo ey y bendingr       from this equation we may find the dimension of the first arm. after knowing the dimension of each arm the weight of each arm may be found and also the total weight of the manipulator structure will be determined. the next step in the analysis is to input those information to the program to began the process of changing the dimension of the cross section to minimize the total error (deflection) at the end of the robot arm this process gives many generations of the dimensions of the arm cross section which satisfies the conditions specified for the maximum and minimum error allowed at the end effecter and also the permissible increase in the weight of the robot structure specified from us, from between all those generation the program select the best generation or probability that gives the lightest weight and the less deformation. the next step in the analysis is to input the new weight of the robot arms to the optimization process for the tri –tube cross section shown in figure(2-b) and trying to find the best dimensions that gives the highest moment of inertia for the cross section so as to minimize the deflection in each arm and also the total deflection of the robot at the end effecter, i.e. the mass of uni –tube section ahmed abdul hussain ali al-khwarizmi engineering journal, vol.4 , no. 1 pp 17-26 (2008) 20 found by the program should be equal to the mass of the tri –tube section which is equal to                ) 4 3 (2)( 4 3 2 222 3 3    d rsddl vm 2/ 3 sin 3 2 dhr   where  is the density of robot arm metal, r is the radius of the two flanges (stiffeners) welded at each end, s is the thickness of the flanges and h is the distance between the vertices of the equilateral triangle. the optimization problem is defined as follow tddh iimize mm tubetri tubeunitubetri 2, )(max     in the optimization problem the thickness of the tubes )(t and the thickness of the flanges )(s are assumed to be 2mm. the results of the optimization problem showed that the tri –tube section that have the same weight (mass) of a uni –tube may improve the stiffness of the robot and minimize the total deflection in about 33%, this results means that we may construct a robot having tri –tube section which is less in weight from that of uni –tube section and both of them having the same end effecter deformation. results: in order to verify the analysis of the previous section a run had been done which has the following characteristics for the robot arm 29 /10200 mne  26 /10120 mnall  , 2sec/81.9 mg  , mlmlml 4.,45.,5. 321  , 3/7850 mkg , m0022.0max  , m0005.0min  , mt 002.0 ( tube thickness ), ms 002.0 (stiffener thickness), kgm 5.91  (mass of the first gear box), kgm 4.42  (mass of the second gear box), kgm 503  (manipulated mass). the available gear boxes for the application are given in the list of table 1 the results of the program shows that for the given configuration the minimum weight for the structure of the uni –tube robot is (wmin=19.986 n), the robot with such structural weight could manipulate the load with out failure because the stress in each arm is less than or equal to the allowable stress, but the deflection of the end point effecter is very large. the iteration process for increasing the dimension of the section to minimize the deflection and letting it be within the range (0.0005< <0.0022) shows that there are 22 generation all of which has a deflection (0.0005< <0.0022) and also a weight (w<factor * wmin ) the permissible weight factor (fac.) for increasing the weight was chosen to be (fac.=1.35). the dimensions of the inner side of the uni –tube section for the 22 generation are shown in fig.(4). the relation between the total deflection at the end -effecter and number of generation is shown in fig.(5). the relation between the new weight of the robot structure and its generation is shown in fig.(6). the program chooses the best generation which has the less variable (variable= weight*deflection), the relation between the variable and the generation is shown in fig(7) it is obvious that the generation no. 16 has the minimum value, the dimensions of the section for that generation are b1 =0.07464m, b2 =0.06397m, b3=0.05657m and has a deflection total =1.87125*10-3 m and a total structural weight wtotal =26.917n. those results are the input for the next step in the program for calculating the dimensions of the tri –tube section in which an optimization problem where solved to maximize the moment of inertia for the section in terms of the dimensions h and d, the results of the program are shown in table (2) the total deflection for the tri –tube configuration   2 1 2 23)(   tubetritotal =1.31462*10 -3 m the deflection for the tri –tube configuration is less than that for the uni –tube which was found to be ( 310*8725.1   tubeuni ) this results shows that the tri –tube section reduces the deflection in a bout 29.7% from that of uni – tube section, the result may be improved to reach a value of 33.38% if we change the weight factor (fac.) to make it equal to (1.3) on the other hand if (fac.) is increased to(1.65) the ahmed abdul hussain ali al-khwarizmi engineering journal, vol.4 , no. 1 pp 17-26 (2008) 21 improvement in deflection would be less and equal to (6.02%) those results for iteration and optimization are shown in table(3) another interesting feature in the design of the uni –tube section is that if the weight factor (fac.) was chosen to be 1.3 and the range of deflection is limited to  <0.0022 we would find only five generation which satisfies the previous mentioned configuration and if (fac.) was changed to 1.65 and  < 0.00104 we would find only 4 generation these results which are shown in table (4) shows the band of limits of the design of robot in other word we can not find a robot with a weight factor less than (fac.=1.3) and has a deflection less than 0.0022m or we cannot find a robot with a weight factor less than (fac.=1.65) and had a deflection less than 0.00104m those results of iteration are shown in table(4). a flow chart of the program used is shown in fig.(8). conclusions: this paper presents a method for optimization of robot design in the conceptual design stage. the robot is modeled in the mathcad package and the optimization problem is formulated as to determine the dimension of robot arm in order to minimize the weight and maximize stiffness this formulation can be interpreted as to design the cheapest possible robot that will still meets the design demands. the optimization method showed good capability in finding an optimum set of dimension of the arm of robot manipulator with three degree of freedom. the optimization method shows that the tri – tube is superior to uni –tube section in minimizing deflection in about 33%. the presented work provides a good support for conceptual robot design. fig. (1) robot configuration (b) (a) fig.(2) (a) uni-tube configuration (b) tri-tube configuration. 2q 2 3l2l 1 3q 1l m3 m1 m2 3 ahmed abdul hussain ali al-khwarizmi engineering journal, vol.4 , no. 1 pp 17-26 (2008) 22 fig.(3) modulation of manipulator links table 1 torque–mass relation for available gear boxes [2] out put torques (n.m) mass (kg) 101 231 572 1088 1499 2176 4361 6135 2.5 4.4 9.5 12.7 18 28 47 69 table (2) dimension of the tri –tube section arm no. h (m) d (m) *10-3 itri –tube(m 4) *10-7 deflection ( ) m *10-4 3 2 1 0.10028 0.10440 0.10440 7.52652 9.22085 11.92 1.75056 2.48207 3.42024 8.09087 7.35704 3.0044 table (3) results for iteration and optimization problem fac. tubetri (m)*10-3 tubeuni  (m)*10-3 improvement in deflection 1.3 1.35 1.4 1.45 1.5 1.55 1.6 1.65 1.39973 1.31462 1.2189 1.16048 1.09686 1.04631 0.985197 .948732 2.10114 1.87125 1.6237 1.48623 1.3437 1.22646 1.08422 1.00955 33.38% 29.7 % 24.9 % 21.9 % 18.37% 14.68% 9.13 % 6.02 % table (4) limits of deflection-weight factor for robot design fac.  max (m) generations 1.3 1.35 1.4 1.45 1.5 1.55 1.6 1.65 0.0022 0.0019 0.0017 0.0015 0.0014 0.0013 0.0011 0.00104 5 2 3 2 3 0 2 4 ahmed abdul hussain ali al-khwarizmi engineering journal, vol.4 , no. 1 pp 17-26 (2008) 23 in ne rsi de d im en si on ( b ) fo r u ni -t ub e se ct io n in (m m ) 1 3 5 7 9 11 13 15 17 19 21 0.04 0.05 0.06 0.07 0.08 0.09 b1 b2 b3 b1 b2 b3 generatonsgenerations fig.(4) correlation between inner side dimension and no. of generations. t ot al d ef le ct io n total (m m ) 0 2 4 6 8 10 12 14 16 18 20 22 0.0017 0.00176 0.00182 0.00188 0.00194 0.002 0.00206 0.00212 0.00218 0.00224 0.0023 generationsgenerations fig.(5) correlation between the deflection and no. of generations. ahmed abdul hussain ali al-khwarizmi engineering journal, vol.4 , no. 1 pp 17-26 (2008) 24 t ot al w ei gh t (n ) 0 2 4 6 8 10 12 14 16 18 20 22 25.5 26 26.5 27 generations generations fig.(6) correlation between robot weight and no. of generations. v ar ia bl e (v a r .) 0 2 4 6 8 10 12 14 16 18 20 22 0.05 0.055 0.06 generations fig.(7) correlation between (variable) and no. of generations. ahmed abdul hussain ali al-khwarizmi engineering journal, vol.4 , no. 1 pp 17-26 (2008) 25 references: [1]. p.s. shiakolas, d. koladiya and j.kebrle “optimum robot design based on task specifications using evolutionary techniques and kinematic, dynamic, and structural constraints”, international journal of inverse problems in engineering, volume 10, number 4, pp 359-375, 2002. [2]. marcus p., peter k., xiaolong f.a., johan a. and doniel w. “industrial robot design optimization in the conceptual design phase”, ieee –mec. of robot, 2004. [3]. abdel –malek k. and paul b., “criteria for the design of manipulator arms for high stiffness to weight ratio”, sme journal of manufacturing systems, vol.17, no.3, pp.209220. [4]. e.i. rivin, mechanical design of robots, 1988, mc grow –hill, inc, new york. [5]. e.j. hearn “mechanics of materials”, pergamon press, 1977. fig.(8) flow chart of the program built-up by the use of mathcad soft ware defining: e, all , m1,m2,m3,  ,t,s, calculation of b3, b2, b1 and wmin=q3*l3+q2*l2+q1*l1 for b1 =b1+0.001 for b2=b2+0.001 for b3=b3+0.001 calculation of: 321 ,,  ,   2 3 2 23  total ,wrobt if maxmin   total if wrobot>fac.*wmin saving generations finding minimum (var=wrobot total ) 1 1 optimization for tri-tube section h>d , wtii-tube=wuni-tube, d 2t maximize (i), find h,d finding: 123 ,,    2 1 2 23,  tubetritotal no no yes yes ahmed abdul hussain ali al-khwarizmi engineering journal, vol.4 , no. 1 pp 17-26 (2008) 26 على أساس التصمیم األمثل ولنسبة جساءة الى وزن ) الروبوت(تقلیل الخطاء في الذراع األلي .عالیة أحمد عبد الحسین علي. د كلیة الھندسة/ جامعة بغداد قسم المیكانیك :الخالصة لطرفي في الذراع األلي ، تم في ھذا البحث تم دراسة تاثیر استخدام المقطع الثالثي األنابیب الدائریھ ألجل تقلیل الخطاء ا اجراء مقارنھ بین المقطع الثالثي األنابیب و المقطع المربع التقلیدي للذراع األلي ، الدراسھ بینت بانھ لكال الذراعین ذات المقطع . ٣٣%الثالثي و المربع والذان لھما نفس الوزن ممكن تقلیل الخطاء بحدود ساب أقل وزن للذراع اآللي ذي المقطع المربع الذي یمكن أن یتحمل األوزان المسلطھ لح mathcadتم كتابة برنامج باستخدام .ویعطي أقل تشوه ي الجزء الثاني من البرنامج یقوم بعملیة األمثلیھ ألجل ایجاد ابعاد المقطع ذي األنابیب الثالثیھ الدائریھ والذي لھ نفس وزن الذراع ذ .المربعالمقطع المربع ولھ تشوه أقل من نضیره all s r min max , d d 2 q t b b b b i tube uni 2 , 12 4 4 = = 2 2 b b a tube uni = ( ) ( ) ( ) 2 2 2 2 2 4 4 60 sin 3 1 4 2 60 sin 3 2 4 64 3 ÷ ø ö ç è æ + ÷ ø ö ç è æ + = h d d h d d d d i tube tri p p p t d d 2 = ( ) t d d d d a tube tri 2 , 4 2 2 = = p ÷ ÷ ø ö ç ç è æ + = 8 3 1 4 3 3 3 3 3 3 3 l q l w ei d g m w a l a l g l g m q = = = ´ = , g r g å + = = 3 3 3 3 0 l q w f f y å + = = 3 3 2 3 3 3 2 0 l w l q mo m ( ) ÷ ÷ ø ö ç ç è æ + + + = 2 8 3 1 3 2 3 4 2 2 3 2 2 3 2 2 l mo l q l w f ei d 3 2 2 2 2 f w l q f + + = 3 2 3 2 2 2 2 2 2 2 mo l f l w l q mo + + + = 1 2 1 1 1 2 ei l mo = d ( ) 2 1 2 2 3 d d d d + + = total 12 2 / * 4 3 4 3 3 3 3 b b b mo i y m = = s 12 2 / * 4 2 4 2 2 2 2 b b b mo = s c e r f f f 1 1 1 + = e f e f 1 c r f f = e f e f 1 c f 1 e r f f = ) / ( 1 1 1 1 1 1 1 e y y y e y e r y e y e y e r y e r a a a s s s s s s s s s s s s s s s s s s + = + = + = + = + = 2 2 4 l i e f e p = a l i e e 2 2 4 p s = 1 2 1 w f f f c + = = a f c y = s ( ) 1 s ( ) 2 mo ( ) 1 1 2 1 2 / * / ! i b mo e y y bending r + + = + = \ s s s s s s ú ú ú ú û ù ê ê ê ê ë é + = = ) 4 3 ( 2 ) ( 4 3 2 2 2 2 3 3 p p p r r d r s d d l v m 2 / 3 sin 3 2 d h r + = p r r s h t d d h i imize m m tube tri tube uni tube tri 2 , ) ( max ³ ³ = ) ( t ) ( s 2 9 / 10 200 m n e ´ = 2 6 / 10 120 m n all ´ = s 2 sec / 81 . 9 m g = m l m l m l 4 . , 45 . , 5 . 3 2 1 = = = 3 / 7850 m kg = r m 0022 . 0 max = d m 0005 . 0 min = d m t 002 . 0 = m s 002 . 0 = kg m 5 . 9 1 = kg m 4 . 4 2 = kg m 50 3 = d d total d ( ) 2 1 2 2 3 ) ( d d d d + + = tube tri total 3 10 * 8725 . 1 = tube uni d d d 3 l d tube tri d tube uni d d 1 3 5 7 9 11 13 15 17 19 21 0.04 0.05 0.06 0.07 0.08 0.09 b1 b2 b3 b1 b2 b3 fig.(4) corrolation betwen inner side dimension and no. of generations generatons inner-side dimension (b) for uni-tube section in (mm) total d 0 2 4 6 8 10 12 14 16 18 20 22 0.0017 0.00176 0.00182 0.00188 0.00194 0.002 0.00206 0.00212 0.00218 0.00224 0.0023 fig.(5) corrolation betwenthe deflection and no. of generations generations total defflection (mm) 0 2 4 6 8 10 12 14 16 18 20 22 25.5 26 26.5 27 fig.(6) corrolation betwen robot wight and no.of generations generations total weight (n) 0 2 4 6 8 10 12 14 16 18 20 22 0.05 0.055 0.06 generations vareant(var) 2 l 3 q 1 l 1 2 3 , , d d d ( ) 2 1 2 2 3 , d d d d + + = tube tri total ³ total d ´ max min d d d á á total 3 2 1 , , d d d ( ) 2 3 2 2 3 d d d d + + = total al-khwarizmi ahmed abdul hussain ali al-khwarizmi engineering journal, vol.4 , no. 1 pp 17-26 (2008) al-khwarizmi engineering journal al-khwarizmi engineering journal, vol.4 , no.1 , pp 1726 (2008 ) minimizing error in robot arm based on design optimization for high stiffness to weight ratio. ahmed abdul hussain ali university of baghdad college of engineering, mech. department (received 8 may 2007; accepted 3 december 2007) abstract: in this work the effect of choosing tri-circular tube section had been addressed to minimize the end effector’s error, a comparison had been made between the tri-tube section and the traditional square cross section for a robot arm, the study shows that for the same weight of square section and tri-tube section the error may be reduced by about 33%. a program had been built up by the use of mathcad software to calculate the minimum weight of a square section robot arm that could with stand a given pay load and gives a minimum deflection. the second part of the program makes an optimization process for the dimension of the cross section and gives the dimensions of the tri-circular tube cross section that have the same weight of the corresponding square section but with less deflection. key word: robot arm stiffness, flexible manipulator, robot structure analysis, flexible link robot. introduction: the links of serial manipulators are usually over designed in order to be able to support the subsequent links on the chain and the pay load to be manipulated. however, increasing the size of the links unnecessarily requires the use of larger actuators resulting in higher power requirements. optimum robot design has been addressed by many researchers as found in the open literature; shiakolas and koladiye [1] discuss the application and comparison of the evolutionary techniques for optimum design of serial link robot manipulators based on task specifications. the objective function minimizes the required torque for a defined motion subjected to various constraints which considering kinematics, dynamic and structural conditions. the design variables examined are the link parameters and the link cross sectional characteristics, the developed environment was employed in optimizing the design variables for a scara and an articulated 3-dof puma type manipulators. in the work developed by marcus pettersson et al. [2] an optimization problem are formulated to minimize the weight of the gearboxes, by choosing different discrete gear boxes, and changing the lengths of the arms continuously, subjected to a few requirements on acceleration capability reach and pay load capacity. analysis of stiffness of manipulator link can be found in abdel malek, k. and paul, b.[3] where aspects of the structural design of the manipulator arm are presented. prismatic joints of manipulator arm are based upon a cross sectional design of the links that provides a high stiffness to weight ratio compared with a hollow round cross-section. the case that we study in this work is the robot that consists of three arms as shown in fig. (1). where the first arm is vertical and the second and third arm are horizontal this gives the maximum reach (completely stretched out) for the robot arm and will yield the maximum deflection for the robot. prismatic joints: most manipulator link crosssection are either hollow round or hollow rectangular. hollow links provide convenient conduits for electric power and communication cables, hoses, power transmission members, etc. rivin[4] has studied the influence of cross-sections on the deflections both in bending and torsion. he had compared hollow square with hollow circular cross sections. rivin states that a square cross section can provide a 69 to 84 percent increase in bending stiffness over a circular hollow cross section with only a 27 percent increase in weight. in this paper a different cross-section is introduced, consisting of three tubes centered on the vertices of an equilateral triangle. this cross section is referred to as a tri-tube configuration the hollow square link will be referred to as a uni-tube configuration, as shown in fig. (2). deflection due to pure bending: links with an open end manipulator are normally modeled as cantilevers. consider a simple cantilever with solid or hollow cross – section as shown in fig.(3).to study the proposed cross –section, we use the following equations for moments of inertia (2nd moment of area) about any diametrical axis through the centroid of area. uni –tube: for the unitube depicted fig.(2,a) the moment of inertia about the neutral axis is where b, b is the outer and inner sides, respectively for the uni-tube construction, t is the thickness of the uni-tube and the area is tri-tube: for the tri-tube depicted in fig.(2,b) the moment of inertia about the neutral axis is where d and d are the out side and inside diameters, respectively, for each tube on the equilateral triangle, t is the thickness of each tube in the tri – tube construction. the area of each tube is to demonstrate the deflection due to loading, consider the third arm beam depicted in fig.(3,c). where m is the mass of each arm, m is the mass of the gear box and the mass of the load to be manipulated at the end of the arm, q is the weight per unit length of the beam, w is the load in newton, g is the gravitational acceleration and l is the length of the arm, a is the cross sectional area of the beam, is the specific density. to get the reactions (force and moment) at the fixed end of the third arm we equate the summation of forces and moment to zero i.e. the same thing may be said for the second arm (fig.3-b) taking in to account the effect of moment in calculating the deflection i.e. the reactions at the fixed end will be for the first arm (fig.3-a) we assume that the deflection at the free end is due to bending moment only and the effect of compressive loads on the whole deflection is neglected therefore the total deflection at the end effecter of the robot manipulator arm will be the sequence of analysis in this work is to calculate the weight of the lightest structure that has a square hollow section and with stand the given loading condition this may be achieved by letting the stress in each arm reaches the maximum allowable stress to avoid failure of the structure, the equation for calculating the stress in the third arm may be written as by letting the stress equal the allowable stress and assuming the thickness of the tube walls to be 2mm we may found the dimension of the third arm, this had been done by the aid of a program built up using mathcad software. the stress in the second arm may also be calculated in the same way i.e. the dimension of the first arm fig.(3.a) is calculated by equating the maximum stress induced in it with the maximum allowable, this maximum stress is found by the rankine-gorden formula [5] which is a combination of the euler and crushing loads for a strut for very short strut is very large, can therefore be neglected and , for very long struts is very small and is very large so that can be neglected. thus . the rankine formula is therefore valid for extreme values of slenderness ratios. it is also found to be fairly accurate for the intermediate values. thus, re –writing the formula in terms of stresses for a strut with one end free and the other fixed and the crushing load on the first arm is the final stress on the first arm is thus the sum of the direct stress calculated by rankine formula and that due to bending generated by the exerted moment as was explained in figure (3-a and b) from this equation we may find the dimension of the first arm. after knowing the dimension of each arm the weight of each arm may be found and also the total weight of the manipulator structure will be determined. the next step in the analysis is to input those information to the program to began the process of changing the dimension of the cross section to minimize the total error (deflection) at the end of the robot arm this process gives many generations of the dimensions of the arm cross section which satisfies the conditions specified for the maximum and minimum error allowed at the end effecter and also the permissible increase in the weight of the robot structure specified from us, from between all those generation the program select the best generation or probability that gives the lightest weight and the less deformation. the next step in the analysis is to input the new weight of the robot arms to the optimization process for the tri –tube cross section shown in figure(2-b) and trying to find the best dimensions that gives the highest moment of inertia for the cross section so as to minimize the deflection in each arm and also the total deflection of the robot at the end effecter, i.e. the mass of uni –tube section found by the program should be equal to the mass of the tri –tube section which is equal to where is the density of robot arm metal, is the radius of the two flanges (stiffeners) welded at each end, is the thickness of the flanges and is the distance between the vertices of the equilateral triangle. the optimization problem is defined as follow in the optimization problem the thickness of the tubes and the thickness of the flanges are assumed to be 2mm. the results of the optimization problem showed that the tri –tube section that have the same weight (mass) of a uni –tube may improve the stiffness of the robot and minimize the total deflection in about 33%, this results means that we may construct a robot having tri –tube section which is less in weight from that of uni –tube section and both of them having the same end effecter deformation. results: in order to verify the analysis of the previous section a run had been done which has the following characteristics for the robot arm , , , , , , ( tube thickness ), (stiffener thickness), (mass of the first gear box), (mass of the second gear box), (manipulated mass). the available gear boxes for the application are given in the list of table 1 the results of the program shows that for the given configuration the minimum weight for the structure of the uni –tube robot is (wmin=19.986 n), the robot with such structural weight could manipulate the load with out failure because the stress in each arm is less than or equal to the allowable stress, but the deflection of the end point effecter is very large. the iteration process for increasing the dimension of the section to minimize the deflection and letting it be within the range (0.0005< <0.0022) shows that there are 22 generation all of which has a deflection (0.0005< <0.0022) and also a weight (w<factor * wmin ) the permissible weight factor (fac.) for increasing the weight was chosen to be (fac.=1.35). the dimensions of the inner side of the uni –tube section for the 22 generation are shown in fig.(4). the relation between the total deflection at the end -effecter and number of generation is shown in fig.(5). the relation between the new weight of the robot structure and its generation is shown in fig.(6). the program chooses the best generation which has the less variable (variable= weight*deflection), the relation between the variable and the generation is shown in fig(7) it is obvious that the generation no. 16 has the minimum value, the dimensions of the section for that generation are b1 =0.07464m, b2 =0.06397m, b3=0.05657m and has a deflection =1.87125*10-3 m and a total structural weight wtotal =26.917n. those results are the input for the next step in the program for calculating the dimensions of the tri –tube section in which an optimization problem where solved to maximize the moment of inertia for the section in terms of the dimensions h and d, the results of the program are shown in table (2) the total deflection for the tri –tube configuration =1.31462*10-3 m the deflection for the tri –tube configuration is less than that for the uni –tube which was found to be ( ) this results shows that the tri –tube section reduces the deflection in a bout 29.7% from that of uni –tube section, the result may be improved to reach a value of 33.38% if we change the weight factor (fac.) to make it equal to (1.3) on the other hand if (fac.) is increased to(1.65) the improvement in deflection would be less and equal to (6.02%) those results for iteration and optimization are shown in table(3) another interesting feature in the design of the uni –tube section is that if the weight factor (fac.) was chosen to be 1.3 and the range of deflection is limited to <0.0022 we would find only five generation which satisfies the previous mentioned configuration and if (fac.) was changed to 1.65 and < 0.00104 we would find only 4 generation these results which are shown in table (4) shows the band of limits of the design of robot in other word we can not find a robot with a weight factor less than (fac.=1.3) and has a deflection less than 0.0022m or we cannot find a robot with a weight factor less than (fac.=1.65) and had a deflection less than 0.00104m those results of iteration are shown in table(4). a flow chart of the program used is shown in fig.(8). conclusions: this paper presents a method for optimization of robot design in the conceptual design stage. the robot is modeled in the mathcad package and the optimization problem is formulated as to determine the dimension of robot arm in order to minimize the weight and maximize stiffness this formulation can be interpreted as to design the cheapest possible robot that will still meets the design demands. the optimization method showed good capability in finding an optimum set of dimension of the arm of robot manipulator with three degree of freedom. the optimization method shows that the tri –tube is superior to uni –tube section in minimizing deflection in about 33%. the presented work provides a good support for conceptual robot design. fig. (1) robot configuration (b) (a) fig.(2) (a) uni-tube configuration (b) tri-tube configuration. fig.(3) modulation of manipulator links table 1 torque–mass relation for available gear boxes [2] out put torques (n.m) mass (kg) 101 231 572 1088 1499 2176 4361 6135 2.5 4.4 9.5 12.7 18 28 47 69 table (2) dimension of the tri –tube section arm no. h (m) d (m) *10-3 itri –tube(m4) *10-7 deflection ( ) m *10-4 3 2 1 0.10028 0.10440 0.10440 7.52652 9.22085 11.92 1.75056 2.48207 3.42024 8.09087 7.35704 3.0044 table (3) results for iteration and optimization problem fac. (m)*10-3 (m)*10-3 improvement in deflection 1.3 1.35 1.4 1.45 1.5 1.55 1.6 1.65 1.39973 1.31462 1.2189 1.16048 1.09686 1.04631 0.985197 .948732 2.10114 1.87125 1.6237 1.48623 1.3437 1.22646 1.08422 1.00955 33.38% 29.7 % 24.9 % 21.9 % 18.37% 14.68% 9.13 % 6.02 % table (4) limits of deflection-weight factor for robot design fac. max (m) generations 1.3 1.35 1.4 1.45 1.5 1.55 1.6 1.65 0.0022 0.0019 0.0017 0.0015 0.0014 0.0013 0.0011 0.00104 5 2 3 2 3 0 2 4 inner-side dimension (b) for uni-tube section in (mm) generations fig.(4) correlation between inner side dimension and no. of generations. total deflection (mm) generations fig.(5) correlation between the deflection and no. of generations. total weight (n) generations fig.(6) correlation between robot weight and no. of generations. variable (var.) generations fig.(7) correlation between (variable) and no. of generations. references: [1]. p.s. shiakolas, d. koladiya and j.kebrle “optimum robot design based on task specifications using evolutionary techniques and kinematic, dynamic, and structural constraints”, international journal of inverse problems in engineering, volume 10, number 4, pp 359-375, 2002. [2]. marcus p., peter k., xiaolong f.a., johan a. and doniel w. “industrial robot design optimization in the conceptual design phase”, ieee –mec. of robot, 2004. [3]. abdel –malek k. and paul b., “criteria for the design of manipulator arms for high stiffness to weight ratio”, sme journal of manufacturing systems, vol.17, no.3, pp.209-220. [4]. e.i. rivin, mechanical design of robots, 1988, mc grow –hill, inc, new york. [5]. e.j. hearn “mechanics of materials”, pergamon press, 1977. تقليل الخطاء في الذراع الألي (الروبوت) على أساس التصميم الأمثل ولنسبة جساءة الى وزن عالية. د. أحمد عبد الحسين علي جامعة بغداد / كلية الهندسة قسم الميكانيك الخلاصة: في هذا البحث تم دراسة تاثير استخدام المقطع الثلاثي الأنابيب الدائريه لأجل تقليل الخطاء الطرفي في الذراع الألي ، تم اجراء مقارنه بين المقطع الثلاثي الأنابيب و المقطع المربع التقليدي للذراع الألي ، الدراسه بينت بانه لكلا الذراعين ذات المقطع الثلاثي و المربع والذان لهما نفس الوزن ممكن تقليل الخطاء بحدود %33 . تم كتابة برنامج باستخدام mathcad لحساب أقل وزن للذراع الآلي ذي المقطع المربع الذي يمكن أن يتحمل الأوزان المسلطه ويعطي أقل تشوه. الجزء الثاني من البرنامج يقوم بعملية الأمثليه لأجل ايجاد ابعاد المقطع ذي الأنابيب الثلاثيه الدائريه والذي له نفس وزن الذراع ذي المقطع المربع وله تشوه أقل من نضيره المربع. defining: e,� embed equation.3 ���, m1,m2,m3, � embed equation.3 ���,t,s, � embed equation.3 ��� � embed pbrush ��� � embed equation.3 ��� 2 � embed equation.3 ��� � embed equation.3 ��� 1 � eq �� embed equation.3 ��� � embed equation.3 ��� m3 m1 m2 3 fig.(8) flow chart of the program built-up by the use of mathcad soft ware yes yes no no finding:� embed equation.3 ���� embed equation.3 ��� optimization for tri-tube section h>d , wtii-tube=wuni-tube, d� embed equation.3 ���2t maximize (i), find h,d 1 1 finding minimum (var=wrobot� embed equation.3 ���) saving generations if wrobot>fac.*wmin if � embed equation.3 ��� calculation of: � embed equation.3 ���,� embed equation.3 ���,wrobt for b1 =b1+0.001 for b2=b2+0.001 for b3=b3+0.001 calculation of b3, b2, b1 and wmin=q3*l3+q2*l2+q1*l1 page 25 _1236645461.unknown _1238937592.unknown _1238977271.unknown _1239145252.unknown _1239587407.unknown _1257023452.unknown _1257176484.unknown _1257176901.unknown _1257176255.unknown _1239760023.unknown _1239585709.unknown _1239587255.unknown _1239584024.unknown _1239585314.unknown _1239583099.unknown _1239583266.unknown _1239051691.unknown _1239145002.unknown 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_1226829966.unknown _1235690633.unknown _1235691262.unknown _1235690109.unknown _1226830001.unknown _1226829657.unknown _1226829939.unknown _1173207870 _1226829543.unknown al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 7894 (2014) numerical investigation of transient heat conduction through a thermal insulation of temperature dependant thermal properties mishaal abdulameer abdulkareem department of mechanical engineering /college of engineering /al-mustansiriyah university e-mail: dr.mishal04@gmail.com (received 13 february 2014; accepted 8 september 2014) abstract the two-dimensional transient heat conduction through a thermal insulation of temperature dependent thermal properties is investigated numerically using the fvm. it is assumed that this insulating material is initially at a uniform temperature. then, it is suddenly subjected at its inner surface with a step change in temperature and subjected at its outer surface with a natural convection boundary condition associated with a periodic change in ambient temperature and heat flux of solar radiation. two thermal insulation materials were selected. the fully implicit time scheme is selected to represent the time discretization. the arithmetic mean thermal conductivity is chosen to be the value of the approximated thermal conductivity at the interface between adjacent control volumes. a temperature dependent specific heat capacity proposed by a 4 th degree polynomial is fitted. a good agreement is obtained when the predicted results are compared with those obtained from the analytical solution. keywords: perlite, finite volume, numerical, implicit, conductivity. 1. introduction the performance of air separation plants and storage tanks for cryogenic liquids and liquefied hydrocarbons depends majorly on the characteristics of its thermal insulating materials. most of these thermal insulations operate under atmospheric or medium vacuum pressure and it use perlite (a loose granulated material of volcanic glass origin heated at 850-900 c o to vaporize the high water content that is trapped in its structure and allowing its volume to be porous and expanded up to 167  times its original volume). a common property of all cryogenic thermal insulating materials is that it operates under high temperature deference between atmospheric air and cryogenic fluid temperatures. therefore, filling it inside a vacuumed leak tight annular space separating the atmosphere from cryogenic fluid vessels is necessary to avoid the drop in its efficiency due to the penetration and freeze of water vapor and carbon dioxide. the sudden filling of an empty cryogenic liquid storage tank initially at atmospheric temperature with a cryogenic liquid at its saturation temperature will initiate a sudden high temperature difference between the terminals of the annular space containing the thermal insulating material. this high temperature difference is behind the dependence of thermal conductivity and specific heat capacity of the thermal insulation material on its temperature. in addition, it will initiate a potential for the evaporation of cryogenic liquid due to the transient heat transfer inside the cryogenic liquid storage tank. this energy loss is of a great economic interest especially when the size of cryogenic liquid storage tank is relatively big. reference [1] presented an analytical doubleseries solution for transient heat conduction in mailto:dr.mishal04@gmail.com mishaal abdulameer al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 7894 (2014) 79 polar coordinates (2-d cylindrical) for multi-layer domain in the radial direction with spatially nonuniform but time-independent volumetric heat sources. inhomogeneous boundary conditions of the third kind are applied in the direction perpendicular to the layers. only homogeneous boundary conditions of the first or second kind are applicable on  = constant surfaces. reference [2] have used the pak-t software package, which is based on the finite element method using the galerkin approach to solve the non-linear transient two-dimensional heat conduction through an insulation wall of tank for transportation of liquid aluminum. the objective was to optimize, under certain boundary conditions, the thickness of the insulation material which its thermal properties is a temperature dependent. reference [3] presented an analytical series solution for transient boundary-value problem of heat conduction in r spherical coordinates. the proposed solution is applicable in spherical cone, hemisphere, spherical wedge or full sphere. spatially non-uniform, (only andr -dependent), time independent volumetric heat sources may be present in the layers. inhomogeneous, time independent,  -dependent boundary conditions of the first, second or third kind may be applied on the inner and outer radial boundaries, and only homogenous boundary conditions of the first or second kind may be applied on the  -direction boundary surfaces. reference [4] has investigated analytically the unsteady heat conduction in composite fiber winded cylindrical shape laminates. this solution is valid for the most generalized boundary conditions that combine the effects of conduction, convection and radiation both inside and outside the cylindrical composite laminates. the laplace transformation has been used to change the problem domain from time into frequency. an appropriate fourier transformation has been derived using the sturm-liouville theorem. due to the difficulty of applying the inverse laplace transformation, the meromorphic function method is utilized to find the transient temperature distribution in laminate. reference [5] has used the cylindrical coordinates and reference [6] has used the spherical coordinates. both references has used the kirchhoff’s transformation to solve analytically the non-linear partial differential equation of transient heat conduction through a hollow cylindrical or spherical thermal insulation material of a thermal conductivity temperature dependent property proposed by an available empirical function. it is assumed that this insulating material is initially at a uniform temperature. then, it is suddenly subjected at its inner radius with a step change in temperature. four thermal insulation materials were selected. an identical analytical solution was achieved when comparing the results of temperature distribution with available analytical solution for the same four case studies that assume a constant thermal conductivity. it is found that the characteristics of the thermal insulation material and the pressure value between its particles have a major effect on the rate of heat transfer and temperature profile. in this paper, the two-dimensional, body-fitted coordinate, non-linear partial differential equation of transient heat conduction through a thermal insulation material of a thermal conductivity temperature dependent property proposed by an available empirical function  cbtak  , [7], and of a temperature dependent specific heat capacity property proposed by a 4 th degree polynomial fit will be investigated numerically using the fvm. this insulating material is initially at a uniform temperature  it . then, it is suddenly subjected at its inner surface with a constant temperature  ot ,  io tt  and subjected at its outer surface with a natural convection heat transfer boundary condition associated with a periodic change in ambient temperature  t and heat flux of solar radiation. two thermal insulation materials will be selected, [7], each of outside radius of  m1 . the first is perlite of thickness  mm800 with a characteristic mean particle diameter of  mmdm 5.0 and density of  3/64 mkg at  pa510 atmospheric pressure. the second is perlite of thickness  mm200 with a characteristic mean particle diameter of  mmdm 5.0 and density of  3/50 mkg at a gas pressure  pa1.0 . the fully implicit time scheme will be selected to represent the time discretization. the arithmetic mean thermal conductivity will be chosen to be the value of the approximated thermal conductivity at the interface between adjacent control volumes. to validate the predicted one-dimensional results, both profiles of the temperature and the rate of heat transfer will be compared with the one-dimensional analytical close form solution, [5], which assumes that only the thermal conductivity of thermal insulation material is a temperature dependant property. mishaal abdulameer al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 7894 (2014) 80 2. finite volume model 2.1. grid generation in the finite volume method, the first step is to divide the domain into a number of discrete control volumes;  rn for one-dimensional domain and  zr nn for two-dimensional domain. a general nodal point is identified by p. in one-dimensional domain, the nodes to the west and east of p are identified by w and e respectively. the west side boundary of the control volume is referred to by ‘w’ and the east side of the control volume is referred by ‘e’, figure (1). in two-dimensional domain, the nodes to the west, east, bottom and top of p are identified by w, e, b and top respectively. the side boundaries of the control volume is referred to by; ‘w’, ‘e’, ‘b’ and ‘top’ for the west, east, bottom and top sides respectively, figure (2). the time domain is divided into a number of time steps of size t . variables at the previous time level are indicated by the superscript (o, old). in contrast, the variables at the new time level are not superscripted [8]. 2.2. initial and boundary conditions of 1-d model consider a hollow cylindrical thermal insulation material of temperature dependent thermal conductivity proposed by an available empirical function  cbtak  , [7], and of a temperature dependent specific heat capacity property proposed by a 4 th degree polynomial fit and of inside radius  1r , outside radius  mr 12  and of infinitesimal thickness z . this insulating material is initially at a uniform temperature  kti 300 . the boundary condition at  1rr  is suddenly subjected with a constant temperature  kto 77 while it is kept at the value of the initial temperature at  mr 12  . no convection or radiation heat transfer at the boundaries and no internal heat generation, as shown in figure (3). fig. 1. one-dimensional control volume. fig. 2. two-dimensional control volume. mishaal abdulameer al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 7894 (2014) 81 fig. 3. initial and boundary conditions of one-dimensional model.        ./50,5.0,8.0,2 ./64,5.0,2.0,1 3 1 3 1 mkgmmdmrvacuumperlite mkgmmdmrairinperlite m m     2.3. discretization of 1-d model the governing one-dimensional energy equation is:     21, 1 rrr r t trk rrt t tc               ...(1) multiply equation (1) by  dtdv. ,  dzdrdrdv ...  and then integrate over the control volume faces, yields;                                r t trk rr dtdzdrdr t t tcdtdzdrdr tt t e w n s top b tt t e w n s top b 1 .... ....   using fully implicit scheme;         dt r t tkr r t tkr ttrrtc tt t we o ppp                          …(2) each of the boundary conditions is substituted into equation (2). then divide each of the resulting equation by t and rearrange yields: u o p o pwweepp statatata  …(3) p o pwep saaaa    t rrtc a po p     since uniform control volumes with size r are used. hence,   rnrrr /12  where  upew ssaa ,,, are listed in table (1). table 1, discretization parameters of one dimensional model. zone wa ea ps us internal nodes 0 0 west boundary 0 east boundary 0 mishaal abdulameer al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 7894 (2014) 82 2.4. initial and boundary conditions of 2-d model. consider a two-dimensional model of liquid nitrogen cylindrical storage tank of a hemispherical dish head. this storage tank is covered with a hollow cylindrical thermal insulation material of temperature dependent thermal conductivity proposed by an available empirical function  cbtak  , [7], and of a temperature dependent specific heat capacity property proposed by a 4 th degree polynomial fit and of inside radius  1r , outside radius  mr 12  . this insulating material is initially at a uniform temperature  kti 300 . the boundary condition at  1rr  is suddenly subjected with a constant temperature  kto 77 , as illustrated in figure (4), and subjected at its outer surface with a natural convection heat transfer boundary condition associated with a periodic change in ambient temperature  t , as shown in figure (5), and heat flux of incident solar radiation, as show in figure (6). the value of the free convection heat transfer coefficient between ambient air and the outer surface of the storage tank is  kmwho ./5 2 , [9], with no internal heat generation. the modeling of periodic change in ambient temperature and the transient heat flux of incident solar radiation due to movement of the sum from sunrise at (time=6:00) to sunset at (time=18:00) are given as follows:             24 122 cosmax time tttt mm  12 3600 , 2 280,300 minmax minmax     t time tt tand ktkt m                    2412,0 126, 24 62 cos 60,0 time time time q time qe                     2418,0 186, 24 122 cos 60,0 time time time q time qt                     2418,0 1812, 24 122 sin 120,0 time time time q time qw  2.5. discretization of 2-d model the governing two-dimensional energy equation is:                              z t tk z r t trk rrt t tc 1  …(4) since the physical domain is non-uniform. therefore, a transformation from physical domain (r, z directions) to computational domain ( ,  directions) is introduced. a two dimensional body fitted coordinate system is used. the jacobian of transformation is defined as follows, [10]:                   z z z z r r r rwhere rzzr zz rr j ,,,: substituting the jacobian of transformation into equation (4) and rearrange, yields:                                                           t tkbj t tkbj t tkaj t tkaj t t tcj 1 1 2 1 …(5) mishaal abdulameer al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 7894 (2014) 83 zzrr zrzr zrzr b zr wherea zr wherea                       1 22 2 22 1 ,:; ,:; multiply equation (5) by  dtdv. ,   ddddv .. and then integrate over the control volume faces, yields;                                                                                        tt t e w n s top b tt t e w n s top b tt t e w n s top b tt t e w n s top b tt t e w n s top b t tkbjdtddd t tkbjdtddd t tkajdtddd t tkajdtddd t t tcjdtddd          1 1 2 1 ... ... ... ... ... using fully implicit scheme;                     dt t tkddbj t tkddbj dt t tkddbj t tkddbj dt t tkddaj t tkddaj dt t tkddaj t tkddaj tttcj tt t sn tt t we tt t sn tt t we o pp                                                                                                                              11 11 22 11 …(6) each of the boundary conditions is substituted into equation (6). then divide each of the resulting equation by t and rearrange yields: u o p o pbbtoptop wweepp statata tatata   …(7) p o pbtopwep saaaaaa    t tcj ao p     ,   1,/1, /1 21     z r n n rr where   upbtopew ssaaaa ,,,,, are listed in table (2). 2.6. solver equations (3) and (7) are solved using the tdma, [8]. 3. thermal conductivity the dependence of thermal conductivity on temperature is suggested by the empirical function  cbtak  , [7]. the values of  cba ,, for the two selected thermal insulation materials are given in table (3). this empirical function is valid in a temperature range of  k40077 . 4. specific heat capacity each of the two selected thermal insulation materials is originally made from quartz glass. therefore, the temperature dependence of specific heat capacity of quartz glass for a temperature range of  k30077 is given in table (4), [11], and its relation with temperature is represented using a 4 th degree polynomial fit as shown in table (5). mishaal abdulameer al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 7894 (2014) 84 5. results and discussion 5.1. 1-d model the one-dimensional model with the chosen values of initial and boundary conditions is shown in figure (3). the first step to validate the numerical solution is to choose the grid and time sizes that are adequate for obtaining the minimum error of results. this task is accomplished through a gird independency test git. two thermal insulation materials were selected, [7]. the first is perlite of thickness  mm800 with a characteristic mean particle diameter of  mmdm 5.0 and density of  3/64 mkg at  pa510 atmospheric pressure, it is associated with a grid size of 50rn . the second is perlite of thickness  mm200 with a characteristic mean particle diameter of  mmdm 5.0 and density of  3/50 mkg at a gas pressure  pa1.0 and it is associated with a grid size of 100rn . a time step of min01t is chosen, as shown in figure (7). the arithmetic mean thermal conductivity is chosen to be the value of the approximated thermal conductivity at the interface between adjacent control volumes, as estimated in table (6). figure (8) shows a good agreement when the numerical results of temperature distribution and the rate of heat transfer, for the two selected thermal insulation materials, are compared with the analytical results at time intervals of hrandt 7224,18,12,6,3 , using a fully implicit time scheme. figure (8) clarify that the characteristics of the thermal insulation material and the pressure value between its particles have a major effect on the rate of heat transfer and consequently the temperature profile. for instance, the dominant heat transfer mode when choosing perlite at  pa510 atmospheric pressure is by heat conduction of the interstitial gas between the particles, whereas the heat transfer by radiation is negligible. when the pressure within a thermal insulation material is lowered to a value, the percentage of heat transfer by heat conduction of the interstitial gas between the particles becomes negligibly small when compared with the percentage heat transfer by radiation and conduction over the bulk material. the gas pressure, at which this is reached, depends on the characteristic diameter of the thermal insulation material. a gas pressure of  pa1.0 is sufficient for perlite with a characteristic mean particle diameter of  mmdm 5.0 . 5.2. 2-d model the two-dimensional model with the chosen values of initial and boundary conditions is shown in figures (4), (5) and (6) respectively. this two thermal insulation materials were selected, [7]. the first is perlite of thickness  mm800 with a characteristic mean particle diameter of  mmdm 5.0 and density of  3/64 mkg at  pa510 atmospheric pressure. the second is perlite of thickness  mm200 with a characteristic mean particle diameter of  mmdm 5.0 and density of  3/50 mkg at a gas pressure  pa1.0 . the arithmetic mean thermal conductivity is chosen to be the value of the approximated thermal conductivity at the interface between adjacent control volumes, as estimated in table (6). in order to obtaining the minimum error of results, a grid size of (25x200) is used to model the domain of the two selected thermal insulation materials with a time step size of min10t , as shown in figure (9). figures (10) and (11) shows the predicted numerical results of temperature distribution and the rate of heat transfer, for the two selected thermal insulation materials, at time intervals of hrandt 4524,18,12,6,3 .the fully implicit time scheme is selected to represent the time discretization. it is assumed that the convergence value is (0.001), which is estimated on the basis of the difference between the predicted values of temperature in two successive iterations. mishaal abdulameer al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 7894 (2014) 85 table 2, discretization parameters of two dimensional model. zone ea wa topa ba ps us internal nodes               11 ba tkj e               11 ba tkj w               12 ba tkj top               12 ba tkj b 0 0 surface (bcdefgh)               11 ba tkj e 0               12 ba tkj top               12 ba tkj b           2/ 1   a tkj w   o w t a tkj         2/ 1   lower dish (jon) 0               11 ba tkj w               12 ba tkj top               12 ba tkj b ohaj  1  thaj o1 east surface (nm) 0               11 ba tkj w               12 ba tkj top               12 ba tkj b ohaj  1  eo qth aj    1 top dish (mlk) 0               11 ba tkj w               12 ba tkj top               12 ba tkj b ohaj  1  to qth aj    1 west surface (jk) 0               11 ba tkj w               12 ba tkj top               12 ba tkj b ohaj  1  wo qth aj    1 face ab               11 ba tkj e               11 ba tkj w               12 ba tkj top 0 0 0 face hi               11 ba tkj e               11 ba tkj w 0               12 ba tkj b 0 0 corner a 0               11 ba tkj w               12 ba tkj top 0 ohaj  1  thaj o1 corner b               11 ba tkj e 0               12 ba tkj top 0           2/ 1   a tkj w   o w t a tkj         2/ 1   corner h               11 ba tkj e 0 0               12 ba tkj b           2/ 1   a tkj w   o w t a tkj         2/ 1   corner i 0               11 ba tkj w 0               12 ba tbkj ohaj  1  thaj o1 mishaal abdulameer al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 7894 (2014) 86 table 3, empirical function for the selected thermal insulation materials, [7]. insulating material empirical function  cbtak  ,  kmw ./ a b c perlite in air papmmdmkg m 53 10,5.0,/64  31025.8  410165.1  0.1 perlite vacuum papmmdmkg m 1.0,5.0,/50 3  4109112.1  12104757.3  678.3 table 4, specific heat capacity of quartz glass, [11]. t (k) 50 100 150 200 250 300 c (kj/kg.k) 0.095 0.21 0.41 0.54 0.65 0.745 table 5, polynomial fit of specific heat capacity for quartz glass.    kkgkjttc n n n ./, 4 0     0 1 2 3 4 -1102.16667 310485582.6  -5109.92778 -7103.9926 -10105.333 table (6) interblock nonlinear thermal conductivity. thermal conductivity arithmetic mean  tke      2/tktk ep   tkw      2/tktk wp   tkb      2/tktk bp   tktop      2/tktk topp  mishaal abdulameer al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 7894 (2014) 87 fig. 4. initial and boundary conditions of twodimensional model.        ./50,5.0,8.0,2 ./64,5.0,2.0,1 3 1 3 1 mkgmmdmrvacuumperlite mkgmmdmrairinperlite m m     fig. 5. change of atmospheric temperature during a typical day. fig. 6. change of incident solar radiation on the wall surfaces of the storage tank in a typical day. fig. 7. git test of one-dimensional model. mishaal abdulameer al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 7894 (2014) 88 (1) temperature (2) heat transfer. fig. 8. time history of predicted results for one-dimensional model. (i) solid line: analytical solution, [5] (ii) dashed line: numerical solution fvm [present work]. mishaal abdulameer al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 7894 (2014) 89 (a) physical domain (b) computational domain fig. 9. two dimensional model, (grid resolution =25x200). mishaal abdulameer al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 7894 (2014) 90 (a) temperature, [k]. (b) heat flux, [w/m 2 ] fig. 10. time history of predicted results for two-dimensional model, insulation material: perlite in air (dm=0.5 mm, =64 kg/m 3 ). mishaal abdulameer al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 7894 (2014) 91 (a) temperature, [k]. (b) heat flux, [w/m 2 ]. fig. 11. time history of predicted results for two-dimensional model, insulation material: perlite vacuum (dm=0.5 mm, =50 kg/m 3 ). mishaal abdulameer al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 7894 (2014) 92 6. conclusions it is found that the characteristics of the thermal insulation material and the pressure value between its particles have a major effect on the rate of heat transfer and temperature profile. the dominant mode of heat transfer when choosing a specific thermal insulation material at atmospheric pressure is by heat conduction of the interstitial gas between its particles, whereas the heat transfer by radiation is negligible. when the pressure within a thermal insulation material is lowered to a vacuum level, the percentage of heat transfer by heat conduction of the interstitial gas between its particles becomes negligibly small when compared with the percentage heat transfer by radiation and conduction over the bulk material. on the other hand, a maximum increase of about is observed when comparing the temperature value of the thermal insulation material at the projected area of the outer surface of the two-dimensional model that is facing the moving source of the incident solar radiation with that of the one-dimensional model. this increase in the temperature is due to the presence of the incident solar radiation and the natural convection heat transfer boundary condition that is associated with a periodic change in ambient temperature. in general, the optimum selection of thermal insulating material for a specific cylindrical storage tank of liquefied cryogenic fluid is that with a minimum heat leakage (minimum boil off rate of cryogenic fluid), a minimum amount of insulating material (minimum cost) and a maximum storage capacity of the storage tank (minimum thickness of the thermal insulating material). this optimum selection is accomplished when choosing the perlite of density  3/50 mkg at a gas pressure  pa1.0 when compared with perlite of density  3/64 mkg at  pa510 atmospheric pressure. 7. references [1] singh s., jain p.k., rizwan-uddin, “analytical solution to transient heat conduction in polar coordinates with multiple layers in radial direction”, international journal of thermal sciences, elsevier, 47, 261-273, 2008. [2] zivkovic m.m., nikolic a.v., slavkovic r.b. and zivic f.t., “non-linear transient heat conduction analysis of insulation wall of tank for transportation of liquid aluminum”, thermal science, vol. 14, suppl., s299-s312, 2010. [3] jain p.k., singh s. and rizwan-uddin, “an exact analytical solution for two-dimensional, unsteady, multilayer heat conduction in spherical coordinates”, international journal of heat and mass transfer, elsevier, 53, 2133-2142, 2010. [4] amiri d.a., kayhani m.h., norouzi m., “exact analytical solution of unsteady axisymmetric conductive heat transfer in cylindrical orthotropic composite laminates”, international journal of heat and mass transfer, elsevier, 55, 4427-4436, 2012. [5] mishaal abdulameer abdulkareem, “analytical solution of transient heat conduction through a hollow cylindrical thermal insulation material of a temperature dependant thermal conductivity”, journal of engineering, university of baghdad, volume 19, no. 11, 1483-1503, november 2013. [6] mishaal abdulameer abdulkareem, “analytical solution of transient heat conduction through a hollow spherical thermal insulation material of a temperature dependant thermal conductivity”, journal of engineering, university of baghdad, volume 20, no. 1, 78-97, january 2014. [7] hofmann a., “the thermal conductivity of cryogenic insulation materials and its temperature dependence”, elsevier, cryogenics, 46, 815-824, 2006. [8] veersteeg h.k. and malalasekera w., “an introduction to computational fluid dynamics: the finite volume method”, longman scientific & technical, england, 1995. [9] holman j.p., “heat transfer”, 7th ed in si units, mcgraw hill, uk, 1992. [10] hoffmann, k.a., “computational fluid dynamics for engineers”, engineering education system, austin, texas, usa, 1989. [11] corruccini r.j. and gniewek j.j., “specific heats and enthalpies of technical solids at low temperatures”, nbs monograph, 21, 1960. mishaal abdulameer al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 7894 (2014) 93 nomenclature a constant b, b bottom b constant c constant c specific heat capacity, kj/kg.k d particle diameter, mm e, e east h height, m ho free convection heat transfer coefficient, w/m 2 .k k thermal conductivity, w/m.k n number of control volumes n, n north q heat flux of incident solar radiation, w/m 2 r distance along the r-direction, m s, s south r1 inner radius, m r2 outer radius, m t temperature, k time time, hr top top top top t time, second w, w west z distance along the z-direction, m greek symbols  change in magnitude  density, kg/m 3  -direction  direction subscripts i initial m mean max maximum value min minimum value o inner surface ∞ ambient air superscripts o old abbreviation fvm finite volume method git grid independency test tdma tri-diagonal matrix algorithm (2014) 7894، صفحة 3، العدد10دجلة الخوارزمي الهندسية المجلم مشعل عبد االمير 94 توصيل الحرارة المتغير مع الزمن خالل عازل للحرارة ذات خواص حرارية تحري عددي ل متغيرة مع درجة الحرارة مشعل عبد األمير عبد الكريم الجامعة المستنصرية /كلية الهندسة / قسم الهندسة الميكانيكية dr.mishal04@gmail.com : االلكتروني البريد الخالصة تخدام تم إجراء دراسة عددية لتوصيل الحرارة ثنائي البعد المتغير مع الزمن خالل عازل للحرارة ذات خواص حرارية متغيرة مع درجة الحرارة باس ثم تعرضت إلى تغير مفاجئ في درجة الحرارة . افتراض أن هذه المادة العازلة كانت في البداية بدرجة حرارة منتظمة وثابتة تم. طريقة الحجوم المحددة ة نتيجة اإلشعاع وبقيمة ثابتة عند سطحها الداخلي وتعرضت إلى انتقال الحرارة بالحمل الحر مقترن بتغير دوري في درجة حرارة الجو وكمية الطاقة الحراري تم اختيار قيمة المعدل الحسابي . التجزئة الزمنية للحل العددي الضمني التام ليمثل نموذجاالتم اختيار . ن مختلفتين لعزل الحرارةيتم اختيار مادت. شمسيال استخدام معادلة من الدرجة الرابعة لتمثل تم كما . للتوصيل الحراري لتمثل القيمة التقريبية للتوصيل الحراري عند الحد الفاصل بين الحجوم المحددة المتجاورة مع تلك المتحصلة من الحل تم الحصول على توافق جيد عند مقارنة النتائج العددية .قيمة السعة الحرارية النوعية للعازل والتي تعتمد على درجة الحرارة .الرياضي mailto:dr.mishal04@gmail.comالبريد mailto:dr.mishal04@gmail.comالبريد (2014) 7894، صفحة 3، العدد10دجلة الخوارزمي الهندسية المجلم مشعل عبد االمير 95 tile of paper zooming image using inverse slantlet transfor al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 5, no. 2, pp 54 65 (2009) image zooming using inverse slantlet transform ahlam hanoon department of computer engineering/ collage of engineering/ university of baghdad email:ahlam@yahoo.com (received 28 september 2008; accepted 2 june 2009) abstract digital image is widely used in computer applications. this paper introduces a proposed method of image zooming based upon inverse slantlet transform and image scaling. slantlet transform (slt) is based on the principle of designing different filters for different scales. first we apply slt on color image, the idea of transform color image into slant, where large coefficients are mainly the signal and smaller one represent the noise. by suitably modifying these coefficients , using scaling up image by box and bartlett filters so that the image scales up to 2x2 and then inverse slantlet transform from modifying coefficients using to the reconstructed image . from the simulation result, it has been found that the reconstructed image is 2x2 larger than the image that found from the inverse without scaling up the coefficients. comparison of image zooming using inverses slt by box and bartlett filters, found that, because of the linear interpolation done by using bartlett the image appears to be smoother than the image obtained using a box filter. the performance of these techniques (image zooming using inverse slt) has been evaluated by computer programs with matlab 7.04 (r2007a) language. keywords: dwt, slt, islt, sclim, box filter, bartlett filter, image zooming. 1. introduction discrete wavelet transforms (dwt , s) are useful in a variety of applications (such as estimation ,compression ,and fast algorithms), partly, because they can provide a relatively efficient representation of piecewise smooth signals. the degree to which a wavelet basis can successfully yield sparse representations of such signals depends on the time localization and on the smoothness properties of the basis function [1]. for example, signal smoothing by non linear shareholding of dwt coefficients preserves edges reasonably well – in part, because the support of each basis function is short with respect to its bandwidth, (thus, we have" constant q'' behavior, or octave – band characteristic , of the associated filterbank) [2,3]. a fundamental tradeoff exist between time localization and smooth characteristic is desirable to obtain a good tradeoff between these two competing criteria in designing wavelet bases. as it is usual for dwt , s, in the slantlet transform the length of the discrete – time basis function and their moments are the vehicles by which time localization and smoothness properties are achieved. although the usual filterbank iteration provides a simple way to general an orthogonal discrete – time basic having an octave-band characteristic. for a fixed number of zero moment, it does not yield a discrete-time basis that is optimal (with respect to time localization [2]. selesnick [2, 3] described the basis functions of slant transform from a filterbank view point, gave explicit solution for the filter coefficients, and described an efficient algorithm for the transform. the dwt described in this paper is based on filter bank structure whose different filters are used for each scale. nevertheless, a very simple efficient algorithm based or recursion is available. in the dwt filter bank described here, the support of the discrete-time basis functions is ahlam hanoon al-khwarizmi engineering journal, vol. 5, no. 2, pp 54 -65 (2009) 55 reduced (by a factor approaching one third for coarse scales). which retaining the basic characteristic that leads clearly to a dwt for finite length signal, (boundary issues do not arise, provided the data length is a power of (2). the filterbank is piecewise linear but is discontinuous. for coarse scales, the converge to piece-wise linear discontinues function. the basis being piecewise linear, is reminiscent of the slantlet transform to which it is compared. however the basis function of the slantlet, like the hadamard transform for example, is nonzero over all of the domain, where the basis functions described there become progressively more narrow, giving a multiresolution decomposition. hence,selenick has the name of slantlet for the transform described here. thus slantlet basis appears especially well suited for treating piecewise linear signal. 1.1. image zooming image zooming is defined as the increase or the reducing of the image size by a fixed ratio. two properties of scaling (zooming) make implementation of scaling easier than that of a general warp transformation. • although pixel distance is not preserved, the expansion or contraction ratio is the same every where. • if the scaling ratio is an integer, the pixel lattice of the target image is a subset or suprest of the lattice of the original image. the first property allows the use of spatially invariant filters and the second property avoids the need for resampling when the scaling ratio is an integer. for the case of scaling up (image enlargement), the methods used involve first resizing the image by padding with zeros, followed by convolution with a two-dimensional spatially invariant linear filter. each filter can be represented by the impulse function, which is called the mask of the filter. two common filters, the box filter and bartlett filter, are used in the enlargement of both grayscale and color images [4]. 2. slantlet transform the slantlet transform is an orthogonal discrete wavelet transform with two zero moments and with improved time localization. the construction of the slantlet is based on a filterbank structure where different filters are used for each scale. let us consider a usual two scale iterated dwt filter shown in figure (1) and its equivalent from figure (2). fig. 1. two-scale iterated filter bank dwt fig. 2. equivelant form using dwt the slantlet filterbank employs the structure of the equivalent form shown in figure (2) but it is occupied by different filters that are not produced with this extra degree of freedom obtained by giving up the product form. filters of shorter length are designed to satisfy the orthogonality and the zero moment condition [1]. for the twochannel case, the daubechicies filter is the shorter filter which makes the filterbank orthogonal and has k zero moments. for k=2 zero moments the iterated filter of figure (2) is of length 10 and 4 but the slantlet filterbank with k=2 zero moment shown in figure (3) has filter length 8 and 4. thus the two-scale slantlet filter length is two samples less than that of a two-scale iterated daubechies-2 filterbank. this difference grows with the increased number of stages. some characteristic features of the slantlet filterbank are orthogonal, having two zero moments and octave-band characteristic. each filterbank has a scale dilation ahlam hanoon al-khwarizmi engineering journal, vol. 5, no. 2, pp 54 -65 (2009) 56 factor of two and provides a multiresolution decomposition, the slantlet transform filter are piecewise linear, even though there is no true structure for slantlet it can be efficiently implemented like an iterated dwt filterbank. therefore, computation complexities of the slantlet are of the same order as that of the dwt, but slantlet transform gives better performance in denoising and compression of the signals [2]. fig. 3. two-scale filterbank using slt. 2.1. derivation of the slantlet filter coefficients [2]. the filter that constructs the slantlet filterbank is gi(n), fi(n) and hi(n). the l-scale filterbank has 2l channel. the low-pass filter is to be called hl(n). the filter adjacent to the low-pass channel is to be called fl(n). both hl(n) and fl(n) are to be followed by downsampling by 2 l . the remaining 2l-2 channels are filtered by gi(n) and is shifted time-reverse to i=1,…..,l-1. each is to be followed by down/sampling by 2 i+1 . the sougth filter gi(n) is described by four parameters and can be written as     11i,...,2i2n 21 1i0,...,2nfor 1        forinbob naoa nig … (1) to obtain gi(n) that sougth l-scale filterbank is orthogonal with 2 zero moment, requires obtaining the parameters ao,a1,bo,b1 m=2 i ))14)(1/((6 22 1  mmms ))1(*/(32 2 1  mmt 2/)1(1  msso )*2)(1)(1*3/(*)1(( 1 mmtmsmto  2/)( ooo tsa  2/)( ooo tsb  2/)( 111 tsa  2/)( 111 tsb  the same approach is for fi(n) and hi(n).           112,...,i2nfor 21 1i0,...,2nfor 1 iinbob naao nih … (2)           112,...,i2nfor 21 1i0,...,2nfor 1 iindod ncoc nif … (3) m=2 i mu /1 3/)12( 2  mv )2/()1(* mvuao  )2/()12(* mvmubo  mua /1  ab 1 mmmq /))1(*/(3 2  )(*1 mvqc  )(*1 mvqd  2/)*21(*1 mvddo  2/)1(*1  vcco 2.2. two-dimensional filter banks a 2-d filterbank can be obtained in a similar manner to the iterated wavelet banks that is composed of separable filters ,although the filterbank itself is not separable. the 2d slantlet transform (2-d slt) of a signal can be obtained by performing 1-d slantlet transform on the row followed by another slantlet transform to the columns as shown in figure(4). in a similar manner, the 2-d inverse slantlet transform (2-d islt) of a signal can be found by applying (1-d islt) on the rows followed by another (1-d islt) to the columns as shown in figure (5). ahlam hanoon al-khwarizmi engineering journal, vol. 5, no. 2, pp 54 -65 (2009) 57 fig.4. scale-two, two dimension slt ahlam hanoon al-khwarizmi engineering journal, vol. 5, no. 2, pp 54 -65 (2009) 58 fig.5. scale-two, two dimensions islt 2.3. generation of slantlet matrix [5,6]. to generat slantlet matrix for a size of [2 l x 2 l ] by using eq.(1),eq(2)and eq(3) we get gi(n),hi(n),andfi(n) ln 2,.....2,1      l ll nhnhnt 2,1       l ll nfnfnt 2,2  1,...,1 li 12,.......,1  in   11*22   kq il     ngknqt i i  1*, 1     ngknqt i i i   121*2,1 11 the slantlet transform of the input signal is x(n).      nxnktky l n    12 0 , the inverse slantlet transform can be computed as shown      kykntnx l k    12 0 , ahlam hanoon al-khwarizmi engineering journal, vol. 5, no. 2, pp 54 -65 (2009) 59 3. zooming method image zooming involves scaling up or scaling down the typically massive amount of data needed to represent an image. image processing is being used to enable people to see what they will look like with a new haircut, a new pair of eyeglasses. 3.1. scaling up this is done by rows an columns that are necessary to enlarge the image without changing it. there are two common methods padding and convolution methods. 3.1.1. padding the initial step in scaling up an image is to make the size right. this is done by padding the enlargement matrix with zeros. starting by inserting a row of zero ' s at the top and one after each row of the original image, will get the image obtain 2n+1 rows if the original had n rows. the same thing can be done for the columns. assume we have 2x2 matrix as below:        1,1,1 1,,   jifjif jifjif zero-padding for a 2 by 2 expansion leads to        1,101,1 000 1,0,   jifjif jifjif if the original image had n rows and m columns, and we want to scale it up by a factor x in the horizontal direction and y in the vertical direction, then the zero-padding image will have x*n+1 rows and y*n+1 columns. 3.1.2. convolution the second step is convolution of zero matrix with 2-d, the function of circular convolution using matlab, is shown in the following: function t=circonv(fil,x) % circonv(fil,x) performs the circular convolution of x with filter fil. % fil(1) is the offset and fil(2:end) are the nonzero filter coefficients % for h=fil(2:end); offset=fil(1); n=length(h); t=zeros(size(x)); for i=0:n-1 t=t+h(i+1)*downshift(x,i); end t=downshift(t,offset); 3.2. box-filter this is known as scaling by pixel replication. because each row is replaced by a number of identical rows and likewise for columns. this is achieved by applying a box interpolation filter. for scaling an image by a factor two in both horizontal and vertical direction use result from image padding and convolve with the box filter of order two, which has mask       11 11 if the original image has n rows, this leads to an image with 2n row, as shown in the following:                               1,1,1,1 1,,, 1,,, jifjifjif iifjifjif jifjifjif hence the rows of zero , s have been replaced with a copy of a pixel values directly above them, and the columns zero , s look on the values of the pixel to their immediate left. note that this convolution kernel has a total mass of four, but since the image had been enlarged four times by zero-padding, the average intensity of the convolution results remains equal to that of the original. 3.3. bartlett filter similar to the box filter, a bartlett can also be applied to scale an image. the effect of convolving a padding image with bartlett filter is ahlam hanoon al-khwarizmi engineering journal, vol. 5, no. 2, pp 54 -65 (2009) 60 to insert between each two consecutive rows of the original image a new row that is the average of the two, and likewise for the columns. in other words, we perform linear interpolation between rows and columns independently. because of this linear interpolation done by using the bartlett filter, the image appears to be smoother than the image obtained using box filter .barlett matrix can be constructed by taking the dot product of row(r) and column(c) and multiply the dot product of(r) and (c) by1/ (scale _factor_ x*scale_factor_y).this is done because the sum of all elements in the resulting dot product is always (scale_ factor_ x*scale_ factor_ y) greater than the desired intensity. for example, in the case of scaling 2x in both horizontal and vertical direction, each pixel is mapped into 4 pixels. in the resulting image we want the intensity to be four times greater than that of the original image in order to maintain the same average intensity level. thus, we want the mass of the bartlett filter to be 4. 4. the proposed system design image zooming using inverse slantlet transform implements image scaling base on scaling up of slantlet matrix then taking inverse slantlet transform, we apply on color images. the type of images used in this work are jpg. 4.1. system functions the function of simulation of scaling up using inverse slantlet transform (color image) of eightscale filterbank is summarized by the following steps: input: image data. step1: read image data. step2: call the slantlet transform algorithm, to generate slantlet matrix (sec. 2.3 above), then scaling up transform coefficients using box & bartlett filters. this is to modifying slantlet matrix. step3: call the inverse slantlet transform algorithm as in step 2, and multiply the modified transpose slantlet matrix by the result of step 2. the above steps are called image encoder as shown in figure. (6). fig.6. image encoder output: the output image appears after scaling up using inverse slantlet transform from modifying the slantlet coefficients by two common methods box and bartlett filters. step4: reconstruct the enlarged image from the new coefficients using the inverse slantlet transforms as in step3. step5: display the result images into a memory space. the above steps are called image decoder as shown in figure (7). fig.7. image decoder hint: applying the ideas of image zooming using inverse slantlet transform of the color image, which is represented by three matrices represent r,g,and b color planes. the first image is separated into this r,g,and b matrices. apply the image zooming using inverse slantlet transform algorithm described above on each matrix, and then combine the results. 4.2. computer test a general computer program computing the two dimension slantlet transform is written using matlab 7.04 for a general nxn 2-d (image). an example of a test is applied to "sunset" picture figure (8). ahlam hanoon al-khwarizmi engineering journal, vol. 5, no. 2, pp 54 -65 (2009) 61 fig.8. the original image using the computer program of the proposed method for computing slantlet transform with scale l of eight take 2-d after resize it to power of two [256x256]. the slantlet transform is taking in row wise then in column wise. in this step the image is decomposed to slantlet coefficients. then taking inverse slantlet transforms the result image is shown in figure (9). fig.9. image using islt applying the scaling up to the slantlet coefficients; then taking the inverse slantlet transform for modifying slantlet matrix by box &bartlett filters the result is shown in figure (10)and figure (11). fig.10. enlarge reconstructed image by box filter. ahlam hanoon al-khwarizmi engineering journal, vol. 5, no. 2, pp 54 -65 (2009) 62 fig.11. enlarge reconstructed image by bartlett filter. figure (12) represents a pictures that is used for testing of image zooming by inverse slantlet transform using box filter and the enlarge pictures are shown in figure.(13). also in the same way a picture that is used for testing image zooming by inverse slantlet transform using bartlett filter and enlarge picture is shown in figure (14). fig.12. the original image ahlam hanoon al-khwarizmi engineering journal, vol. 5, no. 2, pp 54 -65 (2009) 63 fig.13. enlarge reconstructed image by box filter. fig.14. enlarge reconstructed image by bartlett filter. 5. conclusions slantlet transform plays an important role in image applications. due to this multiresolution analysis makes the statistic of many natural images be simplified when they are decomposed. it takes the idea of iterated wavelet decomposition with less length filterbank and without any pre/post processing mechanisms. slantlet transform is an orthogonal dwt and provides improved time localization than dwt. the slantlet filter is piecewise linear, for 2 i *2 i image ahlam hanoon al-khwarizmi engineering journal, vol. 5, no. 2, pp 54 -65 (2009) 64 reaching the ith wavelet decomposition stage that can be done with linear operations without the need to perform an iterated filterbank operations as in wavelet. so from the point of view program, computations of the time of the number of multiplication/ adding operations is reduced and the result can be very fast. slt is less frequency selective than the-traditional dwt filterbank due to the shorter length of the filters. the time localization is improved with the degradation of frequency selectivity. enlarge the slantlet matrix using two common methods box and bartlett filter and taking inverse slantlet transform to modify the matrix. the following points can be concluded from these methods: 1the combination of slantlet transform and scaling up gave good results in comparison with the used scaling up method individual. 2the transformation of the image signal from time domain to time-frequency domain gives better results than that of the transformation to frequency domain. 3the slantlet transform gives good result in the image which contains large smooth region because it has linear filter which works well in linear data and the data in the smooth region is linear. 4the designed system can deal with binary image, gray image as well as color image. 6. references [1] g panad, p.k. dash, a.k. pradhan and s.k. mehar, "data compression of power quality events using the slantlet transform ". ieee. transaction on power delivery, vol.17.2, april 2002. [2] i.w selesenick. "discrete wavelet transform of aaproximation order 2 with improved time localization-the slantlet transform" polytechic university–electrical engineering. gmetrotech centre brooklyn, ny 112013840, 1998. [3] i.w selesnick, "the slantlet transform", ieee.tranction on signal processing, vol.47, no. 5, may 1999. [4] peter chien and emily kwok. psych 221/ ee 362 project: image scaling. prof.brian wandell winter 1999. [5] mohammed hazim abdul – kareem "optimum technique for data file denoising". m.sc. thesis university of baghdad, collage of engineering, electrical eng. dept. june 2007. [6] abbas hussien miry "image compression using slantlet transform", m.sc. thesis university of baghdad, collage of engineering, electrical eng. dept. june 2007. 65 54، صفحت 2، العذد 5مجلت الخوارزمي الهنذسيت المجلذ احالم حنون شنيه (200 9) 65 تكبير الصورة باستخذام التحويل المويل المعاكس احالم حنون شنيه جايعح تغذاد / كهيح انهُذسح/لسى هُذسح انذاسثاخ الخالصت يرى اوال اسرخذاو ذذىيم انًىيم نًا يرصف تح يٍ . هزا انثذث يمىو تركثيش انصىسج انًهىَح. ذسرعًم انصىسج انشلًيح عهى َذى واسع فى ذطثيماخ انذاسثح ديث اٌ . لذسجعانيح عهى ذذهيم االشاسج انى عُاصش يخرهفح نًششذاخ يخرهفح وتًسرىياخ يرعذدج يًا يسًخ تاسرخالص ادق انًيزاخ انري ذذًهها االشاساخ . انًعايالخ انكثيشج هي االشاسج االصهيح وانصغيشج ذًثم انضىضاء ديث يرى ذذذيث انًذذدج انُاذجح يٍ ذذىيم انًىيم تاضافح يعايالخ جذيذج نها ) box and bartlett )يثذا انركثيش ذى اعرًادا عهى طشيمري انًششذيٍ . ويٍ ثى يرى اسرشجاع انصىسج تطشيمح انرذىيم انًىيم انًعاكس ) box and bartlett)ياخىرج يٍ انًذذدج االصهيح تطشيمري انًششذيٍ ذكىٌ اكثش ((bartlettوانصىسج انًكثشج انُاذجح يٍ طشيك يششخ . انُرائج انرى وجذخ اٌ انصىسج انًسرشجعح تعذ انرذذيث راخ دجى يضاعف (.bartlett)فى طشيك يششخ (linear interpolation) تسثة اسرخذاو ال ((boxوضىح وَعىيح يٍ انصىسج انُاذجح يٍ طشيك يششخ matlab. (7.04)جىدج هزج انرمُياخ دسثد تاسرخذاو تشَايج داسىب يع نغح 128 al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 4, no. 3, pp 128-137 (2008) miniature two-fingered robot hand driven by muscle wires actuators a. salam al-ammri, bahaa i. kadim and yarub o. al-azzawi department of mechatronics engineering/ al-khwarizmi college of engineering/university of baghdad (received 9 march 2008; accepted 2 september 2008) abstract in this research, a modified artificial hand with direct control has been designed using electrical artificial muscle wires that receive direct sensory impulses through human hand instead of using the mechanical action to open and close this artificial hand. each finger is designed as a chain and its movements achieved through the conventional arrangement control of the electrical muscles wires. the results indicate that it is possible to design an artificial hand using electrical muscle wire for control it with high accuracy. keywords: muscle wires, shape memory alloy, robotics hands. 1. introduction much work over the recent years have been involved in the creation of a humanoid hand, where degrees of freedom and size of the hand and forearm are designed to be as close as possible to human proportions. over time various hands were built from a simple 2 finger system without a thumb, all the way to an almost exact replication of a human hand, comprising of 4 multi-jointed fingers and a thumb. several forms of actuation have been used in these hands such as electrical revolute motors, dc motors, pneumatic actuators and pneumatic muscles. human being has been developing variety of robots. before the 1970, the industrial robot for simple work in plant were mainly developed then, the robots have been improved and multifunctionalized with the progress of technology. recently, they have extended their fields and uses. particularly the humanoid robot technology attracts high attention of public. the humanoid robot has a high flexibility, so they can work in human environment. the manlike robot such as the humanoid robot is expected to realize novel concepts as tele-existence and coexistence of the human being and robot. there have been several robotic hand implementations that subscribe to different levels of anthropomorphism. thus, researchers have since modified commercially available versions of some these original designs to incorporate more elaborate sensing techniques. human being usually contacts with the external environment with his hand. the robot also needs the hands the end-effecter to interact with the object. the robot hand is divided into three categories: mechanical gripper, special purpose hand, and universal hand . the former two types are for the limited use, so their form is not generally manlike. they are often used for industrial robots. on the other hand, the humanoid robot has the last type of robot hand because it requires handling the various types of objects steadily and smoothly. the universal hand can also be used for other purposes such as teleoperation in space environment and in hazardous environment and tele-surgery. therefore, the development of universal robot hand has been an interesting topic among researchers, and a lot of sophisticated robot hands have indeed developed all over the world [1]. ikuo et al. [1] developed a robot hand having equal number of dof to human hand. the method uses restoring force of elastic element as driving power for grasping an object, so that the hand can perform the soft and stable grasping motion with no power supply. in addition, all the components are placed inside the hand it had a. salam al-ammri al-khwarizmi engineering journal, vol. 4, no. 3, pp 128-137 (2008) 129 equal number of joints and dof to human index finger, and it was also equal in size to the finger of average adult male. the performance of the robot finger was confirmed by fundamental driving test. jessica lauren banks [2] investigated the problem of a tactile sensing platform for anthropomorphic manipulation through the fabrication and simple control of a planar 2-dof robotic finger inspired by anatomic consistency, self-containment, and adaptability. the robot was equipped with a tactile sensor array based on optical transducer technology whereby localized changes in light intensity within an illuminated foam substrate corresponds to the distribution and magnitude of forces applied to the sensor surface plane. the integration of tactile perception was a key component in realizing robotic systems which organically interact with the world. such natural behavior was characterized by compliant performance that could start internal, and respond to external, force application in a dynamic environment. however, most of the current manipulators that support some form of hap tic feedback either solely derive proprioceptive sensation or only limit tactile sensors to the mechanical fingertips. peter scarfe and euan lindsay [3] presented the design and implementation of a low-cost air muscle actuated humanoid hand as shown in figure [1]. it is developed at curtin university of technology. this hand offers 10 individually controllable degrees of freedom ranging from the elbow to the fingers, with overall control handled through a computer gui. the hand was actuated through 20 mckibben-style air muscles, each supplied by a pneumatic pressure-balancing valve that allows for proportional control to be achieved with simple and inexpensive components. the hand was successfully able to perform several humanequivalent tasks, such as grasping and relocating objects. fig. 1. the physical hand and arm comprises 4 fingers. touch bionics [4] developed the i-limb hand as shown in figure[2]; it was a prosthetic upper limb device with five individually powered digits. this replacement hand looks and acts like a real human hand and represents a generational advance in both bionics and patient care. the touch bionics i-limb hand was developed using leading-edge mechanical engineering techniques and is manufactured using high-strength plastics. the result was a nextgeneration prosthetic device that is lightweight, robust and highly appealing to both patients and healthcare professionals. fig. 2. i-limb hand lillian y. chang and yoky matsuoka [5] , presented act thumb kinematics model that unifies several studies from biomechanical literature. they also validated the functional consistency (i.e. the nonlinear moment arm values) between the cadaveric data and the act thumb. this functional consistency preserves the geometric relationship between muscle length and joint angles, which allows robotic actuators to imitate human muscle functionality. tetsuya mouri, etal [6], presented a newly developed anthropomorphic robot hand called kh hand type s, which has a high potential of dexterous manipulation and displaying hand shape, and its master slave system using the bilateral controller for five-fingers robot hand. the robot hand was improved by reducing the weight, the backlash of transmission, and the friction between gears by using elastic body. a. h. arieta1, et al., [7], described an electrically powered prosthetic system controlled by electromyography (emg) signal detected from the skin surface of the human body. the research of electrically powered prosthetic systems is divided into two main subjects. one is the design of the joint mechanism. this mechanism includes mechanical torque-velocity converters and a mechanism to help the proximal joint torque by distal actuators. the other subject is the recognition of the emg signal. for the discrimination of many patterns and nonlinear a. salam al-ammri al-khwarizmi engineering journal, vol. 4, no. 3, pp 128-137 (2008) 130 properties of the emg signal, they propose a controller based on a simple pattern recognition information process. the system also drives 12 servomotors to move the adaptive joint mechanism. kenji kaneko, et al. [8], presented a development of multi-fingered hand, which is modularized and can be attached to life-size humanoid robots. the developed hand has a four fingers with 17 joints, which consist of 13 active joints and 4 linked joints. a miniaturized 6-axes force sensor is newly developed and is mounted on each fingertip for improving the manipulability. a main node controller with i/o, motor drivers, and amplifiers for 6-axes force sensors are also newly developed. these components are equipped in the hand for modularization. the developed hand is designed so about realize about 8 [n] forces on the pad point of stretched finger, supposing transmission efficiency of drive system is 55 [%]. in this study, the mechanisms of hand module, its specifications, and electrical system is also introduced. 2prostheses for partial hands the fundamental difference between a reconstructed hand and any present-day hand prosthesis lies without direct sensation in the latter. although the wearer of a modern hook or artificial hand may receive indirect sensory impulses through shoulder harness or cine plastics muscle pin, the conventional arrangement constitutes only a crude and inefficient signal system which must be supplemented and directed by sight. a hand prosthesis is of little use in the dark. in contrast, there is the exquisite appreciation we receive from the normal hand by feeling. by light touch, coarse touch, response to heat or cold and compass-point discrimination, we appreciate texture, and by muscle, joint, and tendon sense we appreciate size and shape. by combining these sense impressions in our cerebral cortex in the opposite parietal lobe, we can identify from memory an object held in the hand. this is stereo gnosis, a phenomena replaced by no artificial hand now available. figure[3] gives some prostheses for the partial hand fig. 3. the management of the nonfunctional hand-reconstruction vs. prosthesis [9]. a. salam al-ammri al-khwarizmi engineering journal, vol. 4, no. 3, pp 128-137 (2008) 131 3experimental work: the mechanism could be divided into two parts, the mechanical and the electrical part. a. mechanical part: the process of constructing the hand from mechanical view is developed from simple one to respectively complex one as shown in figure [4] where they are designed experimentally depending on the trail and error. figure [4-a], demonstrates the first proposed simple gripper, which consists from two fingers, each with two phalanxes. the phalanxes connected together through nails. each phalanx made of simple wood. the motion of each finger is accomplished by one muscle wire (actuator) and one elastic spring to return the moved phalanx back. with this configuration of the gripper, a problem is appeared, that is since each finger has the two movable phalanxes, and the friction between phalanx and nail are respectively high, therefore the motion is inaccurate and inhomogeneous. also finger is endurable. figure [4-b]. a developed form of the gripper, where it consists of two fingers. each of them composed of three phalanxes. the fingers constructed of chain covered by plastic shield where the shield is cut into three parts to separate three phalanxes to generate a motion as far as similar to human finger motion. it is required to move each phalanx independently, and that may be through connecting each phalanx with independent mw. mw connected to a corpus of t-square as shown from the figure. t-square used to observe the amount of motion or extraction of the mws. also each phalanx is connected to plastic spring and the spring connected to the tsquare. the springs are guided through eye-bolts riveted to the plastic shield. one problem developed here is that the independency of phalanxes is unapproved, that is because there is a leakage developed between the chain and plastic shield, and because of the incorrect connection of plastic springs to the t-square. from the above discussion the problem appeared need solutions. the solution is developed by building the two fingers with three independent phalanxes for each as shown in figure [4-c]. (a) (b) (c) fig. 4. the proposed mechanical hands. it is aimed to have a humanlike hand, and this of-course is very difficult because the mechanism of human hand work the complex one from other mechanical parts of the human body .the human hand consists of fingers and each one is of three phalanxes, and each phalanx may be work independently. something like this mechanism is ought to get, at least for one or two fingers.each phalanx connected to independent tendon that will be connected to the muscle wire needed to activate it. so there will be three mws for each finger alone to have a good catching, these fingers must be durable and reliable, therefore each finger constructed from the components shown in figure [5]. a. salam al-ammri al-khwarizmi engineering journal, vol. 4, no. 3, pp 128-137 (2008) 132 figure [5], shows the components: chain, needles, elastic springs, and tough plastic tendon. the chain mechanism is like bon mechanism in human hand, and the needles work as stops to prevent excessive backward motion, the elastic springs are needed to retrieval phalanxes to their original positions after removing the muscle wire activation. finally the elastic tendons are used as the same one in human hand. the constructed finger is shown in figure [6]. fig. 5. the components of a single finger. fig. 6. the constructed finger design. in this research, it is also used other different parts which are simpler than the previous one, they are shown clearly in figure [7], which are available in the markets. they are used to show the control strategy of activation the smart hand using the muscle wires. (a ) (b) fig. 7. ready hand parts. from figure[7 a and b], two types of ready grippers used and they are different from the direction of motion viewpoint, to show clearly the advantages and disadvantages of using the mw to open the gripper or use it to close(catch) the gripper. belectronical part: the electronic part of activation the muscle wire is not very difficult, but as the number of mws used increases, the complexity of the electronic circuit will increase, and so on. muscle wire must be activated with pulse-widthmodulation (pwm) signal (i.e. on-off) to prevent the overheating case of the mw . in other ward, mw under activation must be putting under cycling (heating and cooling). it is possible to get pwm signal simply through out using 555 integrated circuit. a schematic of activation electronic circuit shown in figure [8]. fig. 8. a schematic of the activation circuit of a single mw. the 555 integrated circuit u1, is a popular chip that contains over 40 transistors, resistors, and diodes. turning its output (pin3) on and off according to the values of r1, r2, and c1, as showed by the following equation: ton=0.69(r1+r2)c1 toff=0.69r2c1 the pwm signal is shown in figure [9]. fig. 9. pwm signal. in this research a lot of mws used to perform the desired function, and since each mw needs respectively large amount of current which is the recommended current required to activate the mw (sometimes current reaches 1 amp, and/or more depending on the length and cross-section area of a. salam al-ammri al-khwarizmi engineering journal, vol. 4, no. 3, pp 128-137 (2008) 133 the mw used) [4], driver used to supply the mws. number of power transistors may be a good choice. a microcontroller used to select the required mw(s) depending on the previous condition. it had been also designed the driving circuit that containing the microcontroller which is at89c51 version and shown in the overall circuit in figure [10]. fig. 10. control cct of activation and selection of mws. ccontrol strategy any muscle wire with a given length has a resistance that changes with length (i.e. the resistance of the mw is a function of its length) [4], and since each mw with a specific diameter needs a recommended current to be activated, the voltage required changes with mw length also. that means a mw with a given length will contracts by a constant length (max. 8% of its original length), and this is a problem appearing in the control system, where to control the motion of the system, the input to the actuator (here mw) must be as a parameter, whereas here the input to the mw is a constant voltage (the recommended one to activate the mw). one of the proposed solutions to this problem in this research is to connect several mws have the same length in a series sequence and separated electrically as shown in figure [11]. fig. 11. schematic of mws connection in series. as shown from figure [11], the activation of one mw will contact or pull the hand with a specific length (5% of its length which is the recommended). to duplicate contraction, that needs activate two mws and so on. to increase the accuracy and smoothness of motion, large number of mws with respectively small length will be required. as a case study, four mws with length 20 cm each and of the same diameter (100 micrometer) used to control the motion of the gripper showed in figure [12]. fig. 12. schematic of gripper controlled by mws actuators. from figure [12] the relationship between the generated distance (d) due to mws activation and the gripper head (h) is calculated practically and gives the graphical relation as shown in figure [13]. fig. 13. graphical relationshp between d and h of fig. 12. the relation mathematically is: h= 124d ...(1) the value of (d) depends directly on the number of activated mws, where activation one mw of 20cm length will generates distance of 1cm (5% of mw length), and as shown in figure [12] the gripper head will reduces to 8cm. since the motion of each mw is constant, then the control strategy that established here is by using on-off algorithm, and so practical & theoretical results took to this algorithm which is explained in table [1]. a. salam al-ammri al-khwarizmi engineering journal, vol. 4, no. 3, pp 128-137 (2008) 134 table 1 practical and theoretical results of controlling gripper catching. mws theoretical experimental d (cm) h (cm) d (cm) h (cm) all mws =off 0 12 0 12 mw1=on, others=off 1 8 0.5 10 mw1=mw2=o n 2 4 1.75 5 mw1=mw2=m w3=on 3 0 2.75 1.08 all mws =on 4 0 4 0 from table [1], it is clearly seen that there is a difference between theoretical and practical results, and that difference starts larger, then smaller and finally die out. this because the activation of one mw will affect the lengths of others not activated mws, and the effect reduced each time increasing the number of activated mws. note that this problem may be possible prevented by putting stops to each mw extreme that is nearer to the gripper side. there are other solutions proposed and may be used, like arranging all mws in parallel form with different length or arranging them in different angles with same lengths and other more depending on the idea researchers may have and that of course depends on the common sense not a general way. it is required also in this research to make the motion of the proposed hand imitate the motion of human hand (i.e. to be what attributed {smart hand} is), and this is possible through making the following process, which had been done in this research: 1. taking a variable resistance (or pot). this potentiometer assembled by a specific mean with human hand as shown in figure [14]. 2. the output voltage of the pot is changed with human hand motion. since the experiment of the mentioned study consists of four mws of 20 cm length each(i.e. four separated motions ), therefore four values of output voltage which is related to four constant motions of human hand must be considered here. another think must be considered here, is that the imitation must as closed to human hand as possible. from table [1], since practical results of gripper head is different from theoretical; therefore the human hand head must be similar to practical values of gripper head. so the values of the potentiometer output selected as shown in table [2]. fig. 14. a human hand composed with a potentiometer. table 2 selection of specific values of pot o/p in hexadecimal exp gripper h (cm) h of human hand potentiometer output voltage (hexa) 12 12 00 10 10 07 5 5 1f 1.08 1.08 3f 0 0 ff from table [2], the values of the potentiometer are taken in hexadecimal because it is the values that are dealt here when talking about control as will be show. and this values are took with respect to the human hand head practically when the output of the pot connected directly to the adc0808 (analog-to -digital converter) , which has the resolution of 8-bit. dcontroller table [2] shows that the voltage of pot(vo/p) is less than 07h, then do nothing, and when 07h<=(vo/p) <=1fh then activate one mw as following: 0 mws 00h<=(vo/p) <07h 1 mws 07h<=(vo/p) <1fh 2 mws 1fh<=(vo/p) <3fh number of activated mws= 3 mws 3fh<=(vo/p) <ffh 4 mws (vo/p) <=1fh a. salam al-ammri al-khwarizmi engineering journal, vol. 4, no. 3, pp 128-137 (2008) 135 the previous conditions must be controlled accurately and that is possible using a control program. e-control program control program (controller) is built in a microcontroller ic at89c51 version using assembly language. it is clearly described in the following flow chart shown in figure[15]: fig. 15. the flow chart of the control program. the electronic circuit is shown in figure [16] and is described clearly in a block diagram shown in figure [17]. . fig. 16. control circuit. fig. 17. block diagram of the control circuit. to discuss the force generated on the proposed hand, it must first to analyze the force generated by a single activated muscle wire. fortunately, it is well known that the recommended recovery weight for a single mw (which is generated from applying a recommended current) of 100µm generated about 1500 n when activated. since the mws of the proposed hand connected in series, the effort (force) therefore is duplicated simply through activation more mws as shown clearly in figure [18]. fig. 18. force generated as a function of no. of actived mws. 4-conclousion in this study the design for a two fingered hand actuated by electrical artificial muscles is presented. four experimental prototypes of a hand were described and used to evaluate the design. a modified hand with direct control has been designed using electrical muscle wires that receive direct sensory impulses through shoulder harness instead of using the mechanical action to open and close the hand. each finger is designed as a chain and its movements achieved through the conventional arrangement control of the electrical muscles wires. an important aspect of the rapid prototype technique was used that this hand will be fabricated in one step, without requiring assembly, while maintaining its desired mobility. the use of muscle wires actuators combined with the rapid fabrication of the non-assembly type a. salam al-ammri al-khwarizmi engineering journal, vol. 4, no. 3, pp 128-137 (2008) 136 hand; reduce considerably its weight and fabrication time. this will make it very useful to be used for applications requiring low weight 5references [1] ikuo ya”o*, kenjiro takemura and takashi maenof "development of a robot finger for five-fingered hand using ultrasonic motors", proceedings of the 2003 ieeursj intl. conference on intelligent robots and systems las vegas, nevada. october 2003. [2] jessica lauren banks "design and control of an anthropomorphic robotic finger with multi-point tactile sensation" m.sc thesis department of electrical engineering and computer science on may 11, 2000,. [3] peter scarfe and euan lindsay "air muscle actuated low cost humanoid hand", curtin university of technology, mechanical engineering, perth, australia, [4] touch bionics, "the i-limb hand", www.touchbionics.com ction vs. prosthesis. [5] lillian y. chang and yoky matsuoka ," a kinematics thumb model for the act hand", proceedings of the 2006 ieee international conference on robotics and automation, orlando , florida , may 2006 [6] tetsuya mouri*, haruhisa kawasaki**, and katsuya umebayashi "developments of new anthropomorphic robot hand and its master slave system" , ieee/rsj international conference on intelligent robots and systems 2005. [7] a. h. arieta1, r. katoh1, h. yokoi1 and y. wenwei2,""development of a multi-dof electromyography prosthetic system using the adaptive joint mechanism", precision engineering laboratory, university of tokyo, tokyo, japan, june 20, 2006 [8] kenji kaneko, kensuke harada, and fumio kanehiro [9] "development of multi-fingered hand for life-size humanoid robots", ieee international conference on robotics and automation roma, italy, april 2007. [10] sterling bunnell, m.d. "the management of the nonfunctional handreconstruction vs. prosthesis", elsevier science ltd.2003. http://www.touchbionics.com/ a. salam al-ammri al-khwarizmi engineering journal, vol. 4, no. 3, pp 128-137 (2008) 137 يذ انساى آلي صغيرة ثنائيت األصابع تقاد بواسطت هشغالث األسالك العضليت يعرب عورناجي, بهاء ابراهين كاظن, عبذ السالم العاهري جايعت بغذاد / كهٍت ىنذست انخٌارسيً/ قسى ىنذست انًٍكاحزًنكس الخالصت فً ىذا انبحث حى حصًٍى ٌذ اصطناعٍت ٌخى انخحكى بيا بشكم يباشز عن طزٌق أسالك عضهٍت اصطناعٍت كيزبائٍت حأخذ إشارة حفعٍهيا كم إصبع يصًى ين سهسهت يٍكانٍكٍت ٌخى ححزٌكيا ين . يباشزحا ين انٍذ انبشزٌت بذال ين فعم يٍكانٍكً ألجم فخح ً غهق ىذه انٍذ االصطناعٍت نقذ ًضحج اننخائج انعًهٍت ً اننظزٌت انو ين انًًكن حصًٍى ٌذ اصطناعٍت .خالل حزحٍب حقهٍذي نهسٍطزة عهى انعضالث االصطناعٍت انكيزبائٍت . ٌخى انخحكى بيا باسخخذاو أسالك عضهٍت اصطناعٍت كيزبائٍت ً بذقت عانٍت 122 al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 4, no. 4, pp122-129 (2008) تأثٍر زٔاٌا االَفراج نًُشآث تحٌٕم انًمطع عهى انُحر انحاصم فً يؤخر انًُشأ ْاديسٕسٍ حسٌٕ يحًذ كرٌى خهف اٌغبِعخ اٌزىٌٕٛٛع١خ/ لغُ ٕ٘ذعخ اٌجٕبء ٚاالٔشبءاد (received 4 april 2007; accepted 13 april 2008) انخالصت احذ اُ٘ إٌّشآد ا١ٌٙذس١ٌٚى١خ اعزخذاِب ٌٍغ١طشح عٍٝ عشعخ عش٠بْ اٌّبء وّب رغبعذ فٟ ( transition structures ) رعزجش ِٕشآد رح٠ًٛ اٌّمطع فٟ اٌجحش اٌحبٌٟ رُ اعزخذاَ عجعخ . رم١ًٍ ع١ٍّخ إٌحش فٟ ِؤخش إٌّشؤ عٍّبً اْ ٕ٘بن فٟ إٌّشآد ا١ٌٙذس١ٌٚى١خ ِٕشؤ رح٠ًٛ فٟ اٌّمذَ ٚآخش فٟ اٌّؤخش ربص١ش ٚاظح (froud number)ِٚٓ رح١ًٍ إٌزبئظ رج١ٓ اْ ٌشلُ فشاٚد ° 90ٚ ° 10 ّٔبرط ِخزجش٠خ ٌّٕشآد رح٠ًٛ اٌّمطع ٚثضٚا٠ب أفشاط ِخزٍفخ ث١ٓ عٍٝ عّك إٌحش اٌحبصً ٚاْ اٌزصبس٠ف اٌعب١ٌخ رغبعذ فٟ ص٠بدح ٔغجخ غٛي إٌحش اٌٝ عّمٗ ، ٌٚغشض اخز١بس افعً صا٠ٚخ أفشاط ٌّٕشؤ رح٠ًٛ اٌّمطع رج١ٓ .رحمك الصٝ لذسح رصش٠ف ٚالً غٛي ٌٍّٕشؤ ٚوزٌه الً عّك ٌٍٕحش ِع صجبد اٌعٛاًِ االخشٜ اٌّؤصشح عٍٝ ع١ٍّخ إٌحش° 40 اْ صا٠ٚخ . ِٕشآد رح٠ًٛ اٌّمطع، سلُ فشاٚد، غٛي ٚعّك االٔغشاف، صا٠ٚخ اعشاف عٛأت إٌّشؤ: انكهًاث انًفتاحٍت :انًمذيت .1 ثبرذ (scour) اْ اٌّشبوً اٌّشرجطخ ثبٌزعش٠خ ٚاالٔغشاف ِعشٚفخ فٟ إٌّشآد اٌّبئ١خ ، فبٌزعش٠خ ٟ٘ أغشاف عض٠ئبد اٌزشثخ ِـٓ ِح١طٙب ثٛاعطخ ر١بس ِبئٟ ٚحذٚس رغ١شاد ِّٙخ فٟ شىً ٚخٛاص اسظ١خ اٌغش٠بْ ثغجت ع١ٍّخ إٌحش ٚخبصخ فٟ ٚلذ رحصً (outlet structures)ِؤخشح ِٕشؤ رح٠ًٛ اٌّمطع ٘زٖ اٌظب٘شح ٔز١غخ خ١بساد رص١ّ١ّخ غ١ش ِٕبعجخ ِٕٙب صٚا٠ب أفشاط عٛأت إٌّشؤ (5) . ٌٚزفبدٞ ع١ٍّخ إٌحش الثذ ِٓ رحذ٠ذ ثعط اٌّزغ١شاد ا١ٌٙذس١ٌٚى١خ ِٕٙب عشعخ اٌغش٠بْ ٚصٚا٠ب االٔفشاط ٌغٛأت ِٕشآد ٚرمذ٠ش اٌضا٠ٚخ اٌّضٍٝ اٌزٟ رحمك الً ِغبحخ ِٓ إٌحش اي ٚرعطٟ اعٍٝ رصش٠ف ١ٌٍّبٖ ثبالظبفخ اٌٝ عضَ رغ١ش اٌّمطع ٚٔٛع١خ اٌزشثخ اٌّغزخذِخ (2) . ِّٚب الشه ف١ٗ اْ ٕ٘بٌه عاللخ ٚص١مخ ث١ٓ و١ّخ إٌحش اٌحبصٍخ ٚلذ أصت . فٟ ِخبسط ٘زٖ إٌّٔشآد ٚث١ٓ اٌشىً إٌٙذعٟ ٌٍّٕشؤ ا٘زّبَ اٌجحش اٌحبٌٟ عٍٝ ِعشفخ افعً صا٠ٚخ أفشاط ٌغٛأت ِٕشؤ رح٠ًٛ اٌّمطع ِٓ ِغزط١ً اٌٝ ِمطع ِغزط١ً ثبثعبد اخشٜ ألً ٚاٌزٟ رحمك ألصٝ لذسح رصش٠ف١خ ٚألً غٛي ٌٍّٕشؤ ٚألً . عّك ٌٍٕحش اٌحبصً فٟ ِؤخش ٘زٖ إٌّشآد :انعًم انًختبري .2 فٟ اٌجحش اٌحبٌٟ رُ اعزخذاَ لٕبح ِخزجش٠خ ٚوّب ِٛظحخ ِع ّٔبرط ٌّٕشؤ رح٠ًٛ اٌّمطع اٌّغزط١ً ( 1 )اثعبد٘ب ثبٌشىً اٌٝ ِمطع ِغزط١ً ثبثعبد أخشٜ ألً راد عٛأت رزغ١ش صٚا٠ب (ع75ُ)lٚثطٛي ِمطع ٌٍمٕبح (°90)اٌٝ (° 10 )أفشاعٙب ِٓ اٌّبس فٟ ٘زٖ اٌمٕبح (flow)ٚاٌزٞ ٠زبصش ثّمذاس ٚعشعخ اٌغش٠بْ اٌّخزجش٠خ (1) ٚلذ اعزخذَ اٌخشت اٌّعبوظ ٌعًّ ٘زٖ إٌّبرط . اٌّخزجش٠خ ٌٙزا إٌّٔشؤ ٚرُ رجط١ٓ االسظ١خ ثبٌشًِ االحّش ٌم١بط ف١ٙب اصٕبء ع١ٍّخ االخزجبس ( l,d)غٛي ٚعّك إٌحش اٌحبصً ٚثزصبس٠ف ِخزٍفخ عٍّب أٗ رُ اعزخذاَ اٌغذ اٌغبغظ اٌحبد (sharp crested weir ) فٟ حغبة اٌزصبس٠ف . ٠ج١ٓ اعّبق اٌغش٠بْ ٚاٌزصبس٠ف اٌّشادفخ ٌٙب (1)ٚاٌغذٚي ف١ٛظح ٔغجخ غٛي االٔغشاف اٌٝ (2 )ٌغ١ّع اٌضٚا٠ب اِب اٌغذٚي رج١ٓ إٌزبئظ اٌّخزجش٠خ (2،3)ٌىً صا٠ٚخ ، ٚاالشىبي ( l/d)عّمٗ ( °90)اٌٝ (°10)ٌعّك ِٚٛلع إٌحش ٌىً حبٌخ ٚرٌه ٌٍضٚا٠ب ِٓ ف١ّب ٌٛ وبْ إٌّشؤ (scale effect )عٍّب اْ ٕ٘بن ربئ١ش ٚاظح حم١مٟ ١ٌٚظ ِخزجشٞ (7) . (2008 )129-122، صفحت 4، انعذد 4 يجهت انخٕارزيً انُٓذسٍت انًجهذ سٕسٍ حسٌٕ يحًذ 123 ٔطٕنٍت نهمُاة انًختبرٌت يماطع افمٍت 1ل شك 1 جذٔل اعًاق انجرٌاٌ ٔانتصارٌف نجًٍع انسٔاٌا  deg b cm l cm q m 3 /s y1 cm y2 cm y3 cm h1 cm h2 cm h3 cm h4 cm h5 cm h6 cm h7 cm 10° 28 56.7 0.03 3.36 3.98 4.15 3.58 3.69 3.78 3.86 3.93 4.02 4.15 0.354 4.08 4.67 4.8 4.15 4.28 4.47 4.55 4.62 4.69 4.8 0.556 4.21 4.89 5.08 4.43 4.49 4.6 4.64 4.98 5.03 5.08 0.957 4.4 5.34 5.55 4.68 4.99 5.13 5.22 5.3 5.38 5.55 20° 28 27.5 0.094 3.55 3.98 4.33 3.8 3.86 3.93 3.98 4.16 4.23 4.33 0.564 4.28 4.81 5.09 4.52 4.63 4.71 4.81 4.03 5.04 5.09 1.42 4.64 5.23 5.54 5.00 4.90 5.11 5.17 5.39 5.50 5.54 1.844 5.3 5.77 6.4 6.64 5.0 6.16 5.77 6.03 6.26 6.4 30° 25.5 17.5 0.18 3.8 4.09 4.47 3.95 4.04 4.10 4.10 4.16 4.37 4.47 0.586 4.07 4.84 5.12 4.7 4.9 4.82 4.95 5.06 5.15 5.11 0.651 3.65 3.87 5.2 3.76 3.82 3.86 3.98 4.02 4.91 5.2 2.33 5.45 6.12 6.8 5.85 6.15 6.17 6.16 6.28 6.43 6.79 40° 25.5 12 0.012 3.32 3.67 4.08 3.56 3.6 3.64 3.67 3.87 3.96 4.07 0.28 3.97 4.31 4.73 4.22 4.31 4.42 4.53 4.6 4.67 4.72 0.66 4.08 4.94 5.21 4.8 4.87 4.9 4.98 5.11 5.19 5.21 2.116 5.01 5.7 6.63 6.1 6.18 5.75 5.7 6.03 6.37 6.63 50° 25.5 8.5 0.253 3.85 4.18 4.64 4.1 4.15 4.24 4.37 4.46 4.52 4.64 1.18 5.2 5.49 5.8 5.35 5.5 5.61 5.66 5.78 5.79 5.8 1.24 5.44 5.76 6.02 5.77 5.56 5.7 5.75 5.96 6.13 6.22 2.00 5.73 5.96 6.15 5.94 5.97 6.2 5.99 6.15 6.3 6.51 60° 25.5 5.8 0.06 3.49 3.79 4.25 3.71 3.76 3.9 4.1 4.2 4.22 4.25 0.87 4.88 5.12 5.54 5.1 5.1 5.1 5.2 5.4 5.51 5.54 1.2 5.18 5.5 5.92 5.4 5.51 5.42 5.7 5.81 5.89 5.92 1.67 5.51 5.67 6.4 5.9 5.61 5.96 6.0 6.2 6.3 6.4 90° 25.5 0.0 0.2 4.67 4.93 5.47 4.91 5.1 5.21 5.38 5.40 5.44 5.47 0.585 3.9 4.14 4.7 4.11 4.26 4.35 4.54 4.6 4.66 4.7 1.828 5.07 5.4 5.98 5.6 5.71 5.89 5.98 5.94 5.95 5.98 2.466 6.0 5.95 7.1 5.9 6.82 6.7 6.9 6.99 7.0 7.1 (2008 )129-122، صفحت 4، انعذد 4 يجهت انخٕارزيً انُٓذسٍت انًجهذ سٕسٍ حسٌٕ يحًذ 124 º(10º ،20º،30º،40) طٕل ٔعًك االَجراف نهسٔاٌا -2-شكم (2008 )129-122، صفحت 4، انعذد 4 يجهت انخٕارزيً انُٓذسٍت انًجهذ سٕسٍ حسٌٕ يحًذ 125 º(50º،60º،90) طٕل ٔعًك االَجراف نهسٔاٌا -3-شكم (2008 )129-122، صفحت 4، انعذد 4 يجهت انخٕارزيً انُٓذسٍت انًجهذ سٕسٍ حسٌٕ يحًذ 126 : انتحهٍم انُظري .3 ٌغشض ل١بط اٌزصبس٠ف اٌّغزخذِخ ِخزجش٠ب رُ اعزخذاَ ( : 3)ِعبدٌخ اٌغذ اٌغبغظ اٌزب١ٌخ ح١ش اْ q = اٌزصش٠ف(َ 3 (صب/ b= (عُ)عـشض اٌغـذ اٌغـبغـظ h = عّك اٌّبء اٌفّعبي (ِزش) cd = ِعبًِ اٌزصش٠ف ٚاٌزٞ رُ ا٠غبد ل١ّزٗ ِخزجش٠ب ( 0.6 )٠ٚغبٚٞ ( froud number) ٚرُ اعزخذاَ اٌّعبدٌخ اٌزب١ٌخ ٌشلُ فشاٚد : ٚثبٌص١غخ اٌزب١ٌخ ح١ش اْ fr =سلُ فشاٚد v1 = (صب/َ)ِعذي اٌغشعخ y1 = لجً ِٕشؤ رحٛصً ( ع25ُ)عّك اٌّبء عٍٝ ثعذ . اٌّمطع ٚٔغجـخ غٛي ِٛلع ٠frٛظح ل١ــُ فشٚاد (2)ٚاٌغذٚي ٌضٚا٠ب أفشاط ِخزٍفخ ٌغٛأت ( l/d)االٔغشاف اٌٝ عّمــٗ ٠ج١ٓ اعّبق اٌغش٠بْ عٍٝ غٛي إٌّشؤ ( 4 )إٌّٔشؤ اِب اٌشىً .ٌٚغ١ّع اٌزصبس٠ف ٚاٌضٚا٠ب اٌزٟ اعزّذد فٟ اٌجحش 2– جذٔل . لٍى رلى فرأد َٔسبت طٕل االَجراف انى عًمّ نجًٍع انسٔاي  انسأٌت (deg) h عًك انًٍاِ (m) a يساحت انًمطع a=b.h (m 2 ) q انتصرٌف (m 3 /s) يعذل انسرعت v=q/a (m/s) fr رلى فرٔد l طٕل انُحر (cm) d عًك انُحر (cm) l/d 10° 1.54 0.431 0.03 0.07 0.122 6.3 0.2 31.5 8.00 2.24 0.354 0.158 0.25 4.6 0.43 10.7 10.8 3.024 0.556 0.183 0.28 10.0 0.54 18.5 15.5 4.34 0.957 0.220 0.335 8.0 0.6 13.3 20° 3.302 0.924 0.094 0.101 0.171 9.0 0.2 45 10.902 3.052 0.564 0.184 0.284 11.0 0.35 31.43 15.4 4.312 1.42 0.329 0.487 9 0.45 20 24.014 6.724 1.844 0.27 0.380 13.0 0.4 32.5 30° 4.7 1.198 0.18 0.150 0.245 8.3 0.9 9.22 11.2 2.856 0.586 0.205 0.324 10.0 1.8 5.5 12.0 3.06 0.651 0.213 0.356 6.2 0.7 8.9 28.0 7.14 2.33 0.326 0.446 12.5 2.0 6.25 40° 0.8 0.204 0.012 0.050 0.107 6.5 0.24 27.1 7.3 1.8615 0.28 0.150 0.240 6.0 0.36 16.6 12.1 3.085 0.66 0.213 0.336 8.5 1.2 7.1 26.32 6.711 2.116 0.315 0.449 13.0 2.25 5.7 50° 6.4 1.632 0.253 0.155 0.252 6.0 0.9 6.6 18.0 4.59 1.18 0.257 0.36 12.0 1.5 8.0 22.2 5.166 1.24 0.219 0.30 19.5 2.83 6.9 25.3 6.451 2.00 0.31 0.413 29.0 4.09 7.1 60° 2.5 0.637 0.06 0.094 0.16 5.0 0.3 16.7 15.4 3.927 0.87 0.22 0.32 10.0 0.8 12.5 19.2 4.896 1.2 0.245 0.343 19.0 1.22 15.5 24.0 6.12 1.67 0.273 0.37 25.0 3.4 7.35 90° 4.7 1.198 0.2 0.167 0.246 4.6 1.3 3.53 7.0 1.785 0.585 0.328 0.53 4.0 0.64 6.25 19.8 5.05 1.828 0.362 0.38 19.0 2.67 7.11 31.0 7.905 2.466 0.312 0.406 21 3.1 6.77 )1...(2 3 2 2 3  bhgcdq )2...(/ 1  gyvfr (2008 )129-122، صفحت 4، انعذد 4 يجهت انخٕارزيً انُٓذسٍت انًجهذ سٕسٍ حسٌٕ يحًذ 127 اعًاق انجرٌاٌ عهى طٕل انًُشأ ٔنجًٍع انتصارٌف 4– شكم (2008 )129-122، صفحت 4، انعذد 4 يجهت انخٕارزيً انُٓذسٍت انًجهذ سٕسٍ حسٌٕ يحًذ 128 : انُتائج ٔانًُالشت .4 ِـٓ رح١ًٍ ٔزبئظ االٔغشاف ٚاٌحبصً فـٟ ِؤخـشح ِٕشؤ رح٠ًٛ اٌّمطع ٌٚضٚا٠ب أفشاط ِخزٍفخ رُ رحذ٠ذ اٌحبٌخ اٌزص١ّ١ّخ اٌّفّعٍخ ٚاٌزٟ رعطٟ الً ِغبحخ ِّىٕخ ِٓ االٔغشاف الوجش رصش٠ف ٚاغٛي فزشح رشغ١ً لجً اٌٛصٛي اٌٝ اعظُ أغشاف . صبثذ ٚثعجبسح اخشٜ فبْ اٌزصبس٠ف اٌعب١ٌخ رغجت فٟ رم١ًٍ ل١ُ عّك ٠ٚظٙش ِـٓ . اٌغش٠بْ لجً ثذا٠خ إٌّشؤ ثعىظ اٌزصبس٠ف اٌم١ٍٍخ إٌزبئظ أٗ وٍّب صاد أفشاط صا٠ٚخ عٛأت إٌّشؤ ٌٍّٕٛرط اٌّخزجشٞ ٠الحـظ ص٠بدح فٟ حغُ إٌحش غٛال ٚعّمب ح١ش ثٍغ الصٝ غٛي ٌٗ . (عُ 4.7) ٚثعّك (ع27ُ)٘ٛ (°90)فٟ صا٠ٚخ ٠ٚظٙش (° 40)ٚإٌّٛرط االوفؤ ٘ٛ اٌزٞ ٠زحمك عٕذ اٌضا٠ٚخ ٚعّمٗ (ع8.5ُ)ف١ٙب عٕذ االخزجبس اْ غٛي إٌحش اٌحبصً ٘ٛ ٚ٘زٖ ٟ٘ افعً (صب/ ٌزش6.3)عٕذ غبلخ رصش٠ف١خ رجٍغ ( ع1.2ُ) إٌزبئظ اٌـّزحممخ ِمبسٔـخ ِع ٔزبئظ اٌضٚا٠ب االخشٜ وّب اْ ٔغجخ ٠frمً ِع ص٠بدح سلُ فشاٚد (l/d)غٛي إٌحش اٌٝ عّمٗ ٌّشحٍخ ِع١ٕخ ِٓ اٌزصبس٠ف ثعذ٘ب ٠ضجذ ثشىً رمش٠جٟ ٚ٘زا (. 2)ٚاظح فٟ اٌغذٚي : االستُتاجاث. 5 ِٓ رح١ًٍ ِٕٚبلشخ إٌزبئظ اٌّخزجش٠خ ٌحبالد االٔغشاف اٌزٟ رحصً عبدح فٟ اسظ١خ اٌمٕٛاد اٌزشاث١خ ٚرٌه فٟ ِؤخشح ِٕشؤ رح٠ًٛ اٌّمطع ٌٚضا٠ٚب أفشاط ِزغ١شح ٌغٛأت إٌّشؤ رُ اٌزٛصً :اٌٝ االعزٕزبعبد اٌزب١ٌخ °( 40)اْ افعً صا٠ٚخ أفشاط ٌغٛأت إٌّٔشؤ ٟ٘ اٌضا٠ٚخ .1 ح١ش حممذ الً غٛي ٚالً عّك ٌالٔغشاف فٟ ِؤخشح إٌّشؤ عٍٝ اٌزٛاٌٟ (ع1.2ُ)ٚ ( ع8.5ُ)ٚثم١ُ ِخزجش٠خ ثٍغذ . (صب/ ٌزش6.3 )ٚرحذ رصش٠ف ِمذاسٖ رزغ١ش (l/d )اْ ِمذاس ٔغجخ غٛي االٔغشاف اٌٝ عّمٗ .2 ثشىً عبَ ثعاللخ عىغ١خ ِع ل١ُ فشاٚد ٌٚغ١ّع اٌحبالد إال .اْ ِمذاس شذح اٌزغ١ش ٠ضداد غشد٠ب ِع ل١ّخ صا٠ٚخ االٔفشاط :لائًت انريٕز. 6 وانتصرٌف 3 q ثا / h عُعّك اٌّبء فٟ اٌمٕبح عّك اٌّبء فٛق اٌحبفخ اٌحبدح ٌٍغذ اٌغبغظ َ h ( ع25ُ)عّك اٌّبء عٍٝ ثعذ لجً إٌّشؤ y1عُ y2عُ عّك اٌّبء فٟ ٔٙب٠خ إٌّشؤ (ع20ُ)عّك اٌّبء عٍٝ ثعذ لجً حبفخ اٌغذ اٌغبغظ y3عُ dعُ عّك إٌحش lعُ غٛي إٌحش θدسعخ صا٠ٚخ االٔفشاط ٌغذساْ إٌّشؤ bعُ عشض اٌغذ اٌغبغظ lعُ غٛي ِٕشؤ رح٠ًٛ اٌّمطع cd ـــ ِعبًِ اٌزصش٠ف vصب / َ ِعذي اٌغشعخ عُِغبحخ ِمطع اٌمٕبح 2 a frـــ سلُ فشاٚد : انًصادر. 7 [1] a .j . aisenbrey , jr. , 1978 , “ design of small canal structure", united states , department of the interior , bureau of reclamation . [2] doddial , d. , 1967 , “ scour below submerged solid bucket – type energy dissipators “ , proceedings 12 th congress international association for hydraulic research , fort collins , u . s . a . , vol. 3 , paper no. c13 , pp. 105 – 116 . [3] ranald v . giles , 1976 , “ fluid mechanics and hydraulics “ . , mc graw – hill book company . [4] raid s . i . al – naqar , 1996 , “local scour downstream of chute structures “ . , university of technology , iraq . [5] vanoni , v . a . , ( editor ) , 1977 , “sedimentation engineering “ , asce , manual and reports on engineering practice – no . 25 , new york , u . s . a . . [6] john a. robeson,m hanif chaudhry and john j. cassidy, 1995," hydraulic engineering ", chapter 7, u.s.a. [7] p.novak, a.i.b. moffat, c.nalluri and r.narayanan,2003,3 rd ed ition, chapter 8, u.s.a. (2008 )129-122، صفحت 4، انعذد 4 يجهت انخٕارزيً انُٓذسٍت انًجهذ سٕسٍ حسٌٕ يحًذ 129 effect of flaring angle of transition structure on the scouring of outlet structure sawsan h. muhammed and karem khalaf hadi department of building and construction engineering/ university of technology abstract the transition structure is considered as the most important hydraulic structure controlling the w/s transtion, morever it decrease the scouring of outlet structure. seven experiment samples for transition structure was used in this research at different angles ( 10° 90° ). it was shown that froud number has a clear effect on the depth of the scouring, morever the high discharge rates cause an increase of the ratio between the length of the scour and its depth. in order to select the best flaring angle it was shown that the angle of 40° has the most discharge rate, least structure length and least angle scour depth, with the firmly of the other factors affecting the scouring of outlet structure. al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 4, no. 2, pp 3745 (2008) ph-control problems of wastewater treatment plants dr. g. m. alwan chemical engineering departement/university of technology (received 6 may 2007; accepted 21 may 2008) abstract experimental investigations have been carried out to investigate the ph-control problems of industrial electroplating wastewater treatment plants. the accurate and sensitive pid control system could treat most problem and disturbances in the normal operation of the water treatment. however, conventional treatment was replaced by proprietary treatment agent called a quasil which was found to be more effective for a wide range of ph. key words: wastewater, heavy metals, precipitation, ph-control. introduction the wastewater from metal plating facilities contains contaminants such as heavy metals, oil and grease, and suspended solid at levels which are considered hazardous to the environment and could pose risk to public health. because of the high toxicity and corrosivity of metal plating waste streams, they require to pre-treatment of their wastewater prior to releasing them to municipal sewers or receiving waters. conventionally, precipitation is the method of choice for removal of heavy metals. of the few precipitation methods, hydroxide and sulfide are the main two methods currently in use and hydroxide precipitation is by far the most widely used method, durhamd and patria, (2006). the control of water-ph plays an important role in these treatments, since each step takes place in a separate tank and the entire treatment requires several control loops to adjust the ph and to get perfect separation of toxic metals. experiment set-up the present work studied several industrial electroplating wastewater treatment plants located in iraq with capacities ranging from (5-20) m 3 /day. the streams of wastewater contain heavy metals such as (cu, fe, cr, cd and ni), oil and grease, suspended solids and chelating or complexing agents. the experimental data were obtained on-site and the water samples were analyized at the laboratories of the ministry of industry in baghdad. the results of the analysis are given in tables (1&2) showing average concentrations taken from several wastewater stations. ph-control the acidity or the alkalinity of any solution can be indicated by the term of ph which stands for the power of the hydrogen ions h + .ph is related to the concentration (or more strictly the activity) of hydrogen ions by the following equation pirece et al, (1970): ph = log10 [ h + ] …(1) also, alkalinity indication relates with hydroxide ion as: poh = log10 [ oh ] …(2) for neutralization process, the measurement equation kwok et al., (2003) is:   502 4log 10 . wkggph  2 10 log …(3) the value of g is zero at neutral point (ph =7). the ph process control is one of great importance in the chemical industry especially wastewater treatment plants. ph process control is widely used as the end point control in the wastewater treatment plants shinsky, (1973). g. m. alwan al-khwarizmi engineering journal, vol. 4, no. 2, pp 37-45 (2008) 38 the control loop mainly includes; sensor, controller and final control element which is almost a control valve. the ph-sensor (electrode) is a primary measuring element and like other primary element its dynamic response characteristics can play a significant role in control loop accuracy and stability. ph electrode dynamically behaves as a first order lag system giusti and hougen, (1961). dynamic modeling of treatment process it is difficult to formulate and identify a mathematical model for the ph process as small amounts of polluting elements will change the process dynamics considerably shinsky, (1973). a general dynamic model of the ph process had been discussed earlier by mcavoy, et al., (1972). they have derived a mathematical model from the first principle, i. e., mass balances for species and by combining their balances with equilibrium and electro-neutrality conditions. honson and dale, (1994) have proposed the dynamic model of the ph system using conservation equations and equilibrium relations. modeling assumptions include perfect mixing, constant density, and complete solubility of the ions involved. however, in the present work, the dynamic model of the single stage ph process is proposed as a first order lag system, i. e., of the type:   phku dt phd  …(4) depended upon the conservation equations of the process and using modeling assumptions which include; perfect mixing, isothermal conditions and complete solubility of the ions. from the control engineer's point of view, a linearized model where both the time constant (τ) and process gain (k) vary with ph and with the buffer concentrations in the system, and u indicate the input feed rate of acid and base solutions. so, the transfer function of the single neutralization stage becomes:       1  s k su sph sgp  …(5) since the wastewater treatment contains several stages of neutralization processes, the overall dynamics model will be:       111 21 21   s......ss k.....kk sg n n o  …(6) where n indicates the number of neutralization stages. in the present work, the values of the time lag (τ) were determined between (3-4) hours and the process gain (k) between (1.5-2.0) ph/(m 3 /hr) for each stage, which always varies depend upon the size of tanks and the operating conditions. dynamic of ph electrode in a continuous flow cell, the ph electrodes responses can be generally, represented by two time constants gusiti and hougen, (1961), one arising from the rate of diffusion of ions into and out of the glass electrode surface, the other from solution mixing within the flow cell. the cells performance function, or transfer function can be written as:     11 1 21   ss sge …(7) where: τ1 is the mixing time constant τ2 is the diffusion time constant. the diffusion time constant is primarily a function of dynamic response of the measuring electrode itself. the mixing time constant is a function of the continuous flow cell in which the electrode measures the ph of the solution. in the present work and by analyzing the experimental responses of the electrodes (process reaction curve method, stephanopouls,1984), the ph-electrode could be represented by the first order lag system as follows:   1 1   s sge  …(8) where the time constant (τ) between (1-2) seconds. however, since the time constant of phelectrode was very small when compared to that of the process, it does not affect the response speed of the ph process. the dynamic model of the process has direct effect on the design of closed-loop control system. then the tuning of selected pid control which depends upon the values of dynamic characteristics of the process (process gain and time constant) gives agreement results with the operating of the wastewater treatment system. to increase the efficiency of the processes, it is better to use computer control system to detect and control directly any disturbances in the process variables in the system (figures 3 & 4). g. m. alwan al-khwarizmi engineering journal, vol. 4, no. 2, pp 37-45 (2008) 39 ph control problems several problems occur as a result of using the ph process control in wastewater treatment plants, these are: 1. the precipitation of heavy metals from the wastewater needed adjusting the alkalinity and acidity of water depend upon the nature of ions while another group of ions is precipitated in both conditions as shown in figure (1). for example, fe ion is precipitated in the acidity condition at ph of (3.0 to 4.0), while ions of cu and cr are precipitated in both conditions at ph of (5.0 to 8.5). other ions of heavy metals such as (zn, cd, and ni) are precipitated in alkalinity condition. these behaviors indicate that the process is required in the multistage process to neutralize and separate the heavy metals and also needing to use automatic control system for each stage. additionally many apparent ph problems are really measurement problems rather than process problems due to the presence of complex agents or chelating, oil and grease and dissolved solid which contaminat the surface of sensor and could affect response and sensivity of ph-detectors. so the sensors are always cleaned and calibrated. 2. the ph process is highly non-linear richter et al, (1974), for any small change in ph of the wastewater means a big change in the bulk concentration. for example, at ph 7 there is 10 times acidity as much as ph 8, and that at ph 7 there is 100 times as much acidity as at ph 9. then, the adjustment of ph with high accuracy is now recommended. the above problem could grow to a complex situation when the wastewater has more than three types of heavy metals bakkaloglu et al, (1998). advanced and accurate control system now is needed to adjust the dosing flow of acid / base solution. the experimental results have proved that the regulating pid controller is shown in figure (2), more effective than on-off type, since pid action has operate in regulated characteristics which give it enough time to correct the error. 3. since the wastewater streams have various values of ph regarding the conditions of industrial process, the acidity of water must be monitored directly before any treatment. the ph of a mixed solution (wastewater and acid / base solution) is not just an average of the two solutions of ph values, but is also determined by the power of the solutions, and to a lesser extent by more esoteric factors bailey, (1980). for example, when a solution of caustic soda with ph of 8.3 is added to the wastewater of ph 8, the mixed solution would actually be below ph 8. in the present work, the optimum ph of hydroxide precipitation was between 8.5 to 9.5 while for sulfide was between 3.0 to 4.5. these values were limited experimentally through several sets of experimental runs. it is recommended to use sensitive electrode to detect any small change in measurements. also perfect noise-filter is implemented with the sensor to reject any undesirable signals to the controller. 4. it is difficult to formulate and identify a mathematical model for the ph process as small amounts of polluting elements in the wastewater would change the process dynamics considerably. consequently, interpreting ph problems and solution requires knowledge of more than just the ph of the solutions involved. the entire treatment involves other processes such as, flocculation with a polymeric material, settling…etc, to get acceptable concentration limit of the heavy metals as shown in table (2). this technique is time consuming and requires extensive set-up. several private communications were made with international companies to get better design. finally the result was, new technique called "aquasil" treatment. this technology is commercially introduced in 1995 as an efficient alternative to conventional practices. aquasil wastewater treatment aquasil technology is an innovative treatment process that takes up and removes contaminants from wastewater. in the present work, several experiments were made by using aquasil solution which proved good efficiency of separation as shown in table (2). the aquasil agent is a single product, simultaneous process that utilizes the principles of fast kinetics and synergy for the removal of the most contaminants from the waste stream by using only single separator (figure5). so the ph-control problems could minimize as a result of reduced process stages because the aquasil agent was effective in the wide range of ph from 2 to 12. also it lowers the level of cod and tds. g. m. alwan al-khwarizmi engineering journal, vol. 4, no. 2, pp 37-45 (2008) 40 conclusions 1) the precipitation of heavy metals from the wastewater is achieved through several values of ph-solution depending upon the nature of ions. 2) it is difficult to formulate and identify a mathematical model of wastewater treatment process. it behaves dynamically as a multicapacity system and the approach dynamics model of each stage taken to be a first order lag system. 3) automatic control of water-ph plays an important role in the waste treatment process. 4) advanced on-line pid control has better efficiency than on-off type for the nonlinear ph process which can measure and treat directly any undesirable process signals. 5) ph control problems great with the conventional treatment of multistage process compared the modern and efficient single stage aquisil treatment. table 1 analysis of heavy metals in the raw wastewater. constituen t concentration (mg/liter) cd 60.0 cr 50.0 cu 15.0 fe 20.0 ni 50.0 zn 40.0 table 2 analysis of heavy metals after treatment by (conventional and aquasil technique). constit uent concentration (mg/liter) conventi onal aqu asil cd 1.0 0.6 cr 0.7 0.3 cu 0.3 0.1 fe 0.9 0.6 ni 0.4 0.2 zn 0.3 0.1 nomenclature cod: chemical oxygen demand. g: distance from neutrality given by [ h + ] – [ oh ]. g(s): transfer function. ge(s): transfer function of ph – electrode. go(s): overall transfer function of process. gp(s): transfer function of ph – process tank. k: process gain(ph/(m 3 /hr)). kw: dissociation constant of water. (mole/ liter) h + : concentration of hydrogen ion (mg / liter). oh + : concentration of hydroxide ion (mg / liter). ph: acidity indication. phi: acidity indicator (sensor). pid: proportional, integral and derivative controller. poh: alkalinity indication. s: laplace transform. tds: total dissolved solids. t: time (hours). τ: time constant. g. m. alwan al-khwarizmi engineering journal, vol. 4, no. 2, pp 37-45 (2008) 41 fig. 1. precipitation of heavy metals. fig. 2. flow diagram of pid control system. g. m. alwan al-khwarizmi engineering journal, vol. 4, no. 2, pp 37-45 (2008) 42 fig. 3. hardware components of on-line control system. fig.4. block diagram of the computer control function. operational amplifier noise filter a / d converter transmitter d / a converter d ig it al c o m p u te r w as te w at er tr ea tm en t p la n t g. m. alwan al-khwarizmi engineering journal, vol. 4, no. 2, pp 37-45 (2008) 43 f ig . 5 . f lo w d ia g ra m o f a q u a si l t re a tm e n t. g. m. alwan al-khwarizmi engineering journal, vol. 4, no. 2, pp 37-45 (2008) 44 references [1] durham, b. and patria, l., "wastewater a reliable water resource", chem. engng, october, 50, (2006). [2] pierce, w.c., haenisch, e.l., and sawyer, d.t., "quantitative analysis", john-wiley, (1970). [3] kwok, d.p., deng, z.d., and leung, t.p., "fuzzy neural control of systems with unknown dynamics using q-learning strategies", proceeding of the 12 th ieee, international conference on fuzzy systems, vol. 1, 25-28, may 2003. [4] shinsky, g., "ph and control in process and waste stream", john wiley, n.y, (1973). [5] mcavoy, t. j., hsu, e., and lowenthal, s., "dynamics of ph in a controlled stirred tank reactor", ind. eng. chem. proc. des dev., vol. 11, p. 68, (1972). [6] henson, m. a. and dale, e. s., "adaptive nonlinear control of a ph neutralization process", ieee tran. cont. sys. tech., vol. 2, no. 3, aug. (1994). [7] giusti, a.l., and hougen, j.v., "dynamic of ph electrodes", control engineering, april, (1961). [8] stephanopouls, g."chemical process control, an introduction to theory and practice" , prentis-hall, 2 nd edition, n.g., (1984). [9] richter, j.d., fournier, c.d., ash, r.h., and marcikic, s., "waste neutralization controldigital simulation spots nonlinearities", instrumentation technology, april, (1974). [10] bakkaloglu, t.j. et al, "screening of various types biomass for removal and recovery of heavy metals (zn, cu, ni) by biosorption, sedimentation and desorption", water science & technology, 38, 6, p.269277, (1998). [11] bailey, p.l., "analysis with ion-sensitive electrodes", john-wiley, (1980). g. m. alwan al-khwarizmi engineering journal, vol. 4, no. 2, pp 37-45 (2008) 45 مشاكل السيطرة على الحامضيت في محطاث معالجت المياه الصناعيت غانم مقبول علوان قسى انهُذست انكيًياويت / انجايعت انتكُىنىجيت الخالصت نقذ تبيٍ بأٌ . يشًم انبحث دراست انًشاكم انخاصت بانسيطرة عهً حايضيت يياِ انتصريف انصُاعيت نًصاَع انطالء انكهربائي يًكٍ استبذال . استخذاو يُظىيت سيطرة حساست ودقيقت نها انقذرة عهً يعانجت انكثير يٍ انًشاكم واالزعاجاث انتي تىاجّ عًهيت يعانجت انًياِ . االسهىب انًتبع انقذيى وانسائذ بطريقت أفضم عٍ طريق انًعانجت بًادة األكىاسم وانتي وجذث بأَها تعًم بًذي كبير نهحايضيت (microsoft word \325\341\307\315 \346\344\346\321116-122) al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 14, no.2, june, (2018) p.p. 116122 desalination of highly saline water using direct contact membrane distillation (dcmd) salah s. ibrahim* noor a. mohammad ameen** *,** department of chemical engineering / university of technology/baghdadiraq **email: nourayad2017@yahoo.com (received 10 0ctober 2017; accepted 20 december 2017) https://doi.org/10.22153/kej.2018.12.005 abstract in this work, laboratory experiments were carried out to verify direct contact membrane distillation system’s performance in highly saline water desalination. the study included the investigation of various operating conditions, like feed flow rate, temperature and concentration of nacl solution and their impact on the permeation flux were discussed. 16 cm2 of a flat sheet membrane module with commercial poly-tetra-fluoroethylene (ptfe) membrane, which has 0.22 μm pore size, 96 µm thickness and 78% average porosity, was used. a high salt rejection factor was obtained greater than 99.9%, and the permeation flux up to 17.27 kg/m2.h was achieved at 65°c for hot feed side and 20°c for cold side stream. keywords: membrane distillation, desalination, dcmd process. 1. introduction the supply and demand for sweet water were progressively increasing throughout the last two decades. commercially, desalination of saline water is achieved by either membrane or thermal methods. thermal process typically involves saline water boiling or evaporation then collecting resultant distillate, examples of such process are multi-effect desalination and multistage flashing while membrane process produces fresh water from the saline water using reverse osmosis (ro) principle at a high pressure [1]. membrane distillation (md) is a conjunction of the two processes and can be defined as a thermal membrane process resulting from simultaneous mass and heat transfer phenomena across a hydrophobic microporous membrane [2]. the temperature gradient between liquid-vapor interfaces will generate a pressure difference across the membrane sides which represent the driving force of the process [3]. the process starts when the solution is evaporated alongside the membrane boundary layer after heated to a specific temperature in the feed side. the pure water is produced at the cold side by condensing the vapor which passed through the dry pores of the membrane [4]. at each pore entrance a liquidvapor interface is created due to the membrane hydrophobic nature that inhibits the liquid solution from penetrating into the pores [5].the ability of membrane to operate at lower operating temperatures (30-80 °c) is considered the main advantage of membrane technology than conventional distillation (˃100 °c) and lower operating pressures (˂100 kpa) than conventional membrane processes that are driven by pressure like in reverse osmosis (˃10 bar) [6]. fouling is occurring less in md than other membrane processes such as, reverse osmosis because of the membrane pore size is greater than that used in ro process [7]. md can be operated with the solar energy as a substitution energy sources. membrane distillation has four principal configurations which are classified depending on the method used to withdrawn the vapor that salah s. ibrahim al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 116122 (2018) 117 formed in the hot side of the membrane [8]: (1) direct contact membrane distillation using cooled water for the purpose of condensing vapor at permeate side directly inside the membrane module [9]. (2) vacuum membrane distillation (vmd) employing a vacuum pump at the permeate side to pull the volatile molecules from feed solution. the water vapor condenses in the membrane unit or in a separate condenser [10]. (3) air gap membrane distillation (agmd) using a stationary air hole at the permeate side between the condensation surface and membrane layer. the vapor condenses within the membrane module [11]. (4) sweeping gas membrane distillation (sgmd) utilizing a chilly inefficient gas for sweeping the vapor molecules from the cold side, and the condensation happens at the outer membrane unit [12]. the md process has a competitive advantage for the desalination of brackish and sea waters [13]. in addition, md is considered efficient operation for removing heavy metals and also the organic components from waste and watery solutions [7]. however, md has some disadvantages for example low production rate of distilled water in comparison for desalination technologies such ro. the permeation flux is high sensitive to temperature and concentration of the inlet conditions owing to the fact of temperature and concentration polarization phenomenon. also, heat wasted by conduction is relatively large. 2. transport mechanisms mass and heat transfer are taken place at one time in the md process. the fluid boundary layers occur neighboring the two hot and cold membrane sides [8].over the feed side boundary layer, the feed temperature decreases from tbf to the value of tmf when reach the surface of membrane. evaporation of some water occurs and diffuses through the dry pores of hydrophobic membrane to the permeate side, at the same time; heat transfers across the membrane layer by the conduction. on the other hand, permeate temperature rises from the value tbp over the cold boundary layer and reaches tmp value at membrane surface [14]. the existence of the two boundaries leads to temperature polarization which lowering the trans-membrane temperature. heat is transmitted in three stages: (1) from feed solution to the surface of membrane by convection. (2) across the membrane layer by conduction and (3) from membrane surface to permeate side by convection. transferring of mass in md usually happens by diffusion and convection of vapor during the porous membrane. the feed solution contains a non–volatile component, with the passage of time the concentration of these components at the surface of the membrane (cmf) becomes much higher than that at the bulk feed (cbf), giving rise to concentration polarization [15]. there are three mechanisms used for describing how the vapor molecules can pass through the membrane pores [14]: (1) knudsen diffusion (2) poiseuilleflow (3) molecular-diffusion. figure (1) illustrates the dcmd process with concentration and temperature variations. fig. 1. dcmd process with concentration and temperature variations. 3. materials and methods 3.1. membrane and membrane module dcmd system was equipped with a 0.22 μm flat sheet commercial poly-tetra-fluoroethylene (ptfe) membrane (membrane, spain) having a thickness of 96µ m ,78% of average porosity, 1.27 nm roughness and 114 contact angle. membrane module was designed and constructed in italy (delta company, cosanza, rende, italy), and the membrane effective area was 16 cm2. the module is made of silicones that withstand corrosion by the nacl solution and has a good heat transfer resistance. figure (2) shows the membrane module. salah s. ibrahim al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 116122 (2018) 118 fig. 2. membrane module. (a) inside the module, (b) outside the module. 3.2. experimental set-up and procedure module and all lines of the experimental system were set and well insulated for lowering the amount of heat that loses toward the surrounding environment. the temperatures of the four streams were recorded at the input and output of the both warm and cool channels before the connection points with the membrane module by four thermometers. the mass permeation of clean water was computed by the volume change of distillate cylinder, multiplied by water density and then divided by the membrane area and operating time. the experiments were conducted on a saline solution that was prepared in laboratory with various nacl concentrations (0, 15, 35, 70 and 100 g/l). the hot feed and the coolant for the dcmd were circulated in counter-current flow method. experiments were accomplished by using different feed temperatures in the range (45, 50, 55, 60, and 65 °c). the feed flow rate was investigated at various levels changed from 0.3 to 1.07 l/min, while the permeate flow rate was remained constant for the all tests. the diagram of the experimental rig of dcmd is shown schematically in figure (3). 4. results and discussion in this part, the obtained results of dcmd system are first presented and discussed to illustrate how the membrane's performance is affected by operational conditions. 4.1. effect of feed temperature figure (4) exhibits the impact of the hot feed temperature on the distillate production at different concentrations. temperatures were used from 45 to 65 ° c and they were changed every five degrees at different concentrations (35 and 100 g/l of nacl), whereas the feed flow rate was preserved fixed at 1.07 l/min. it can be noted that for both salt concentrations, the permeate flux increased with the temperature increasing. this phenomenon can be clarified by increasing the driving force (vapor pressure) as a result of the temperature increase. the vapor partial pressure depends on temperature exponentially, as described by antoine’s equation [1]: p° = exp (a b/(c +t)) . . .(1) the production flux was increased by 116.56 % by changing feed temperature from 45°c to 65 °c. obviously the impact of feed temperature is quite controlling the permeate flux. figure (5) offers how the temperature change effects on the percentage of salt rejection and the permeate conductivity for a saline solution with 35 g/l nacl. it can be seen that the permeate conductivity increases slightly when the temperature increases. this behavior indicates that the feeding temperature has a clear influence on the membrane pore wetting process. the permeate conductivity ranged between (8-12) μs/cm with salt rejection achieved about 99.98% salah s. ibrahim al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 116122 (2018) 119 fig. 3. schematic diagram of the experimental rig of dcmd process. fig. 4. the impact of feeding temperature on the resulting flux at various concentrations and 1.07 l/min feed flow rate. fig. 5. effect of the feeding temperature on the permeate conductivity and salt rejection at 35 g/l nacl, and 1.07 l/min feed flow rate. 4.2. effect of feed flow rate figure (6) manifests the influence of feed flow rate in a range (0.3-1.07 l/min.) on the permeation flux at various temperature levels (45, 55, 65 °c) and fixed concentration 35 g/l of feed salt solution. the permeate flux increased approximately linearly with increasing feed flow rate. the increase in flux is become noticeable when both the feed flow rate and the feed temperature are increased at the same time. when the feed flow rate increased from 0.3 to 1.07 l/min the flux increased about 46.62% at 55 ºc and 67.1% at 65 ºc feed temperature. this behavior can be explained through the fact that when feed flow rate increased, the membrane surface temperatures become near to that of the bulk streams, and thus lead to increase the temperature variations across the membrane and enhance the permeate flux. salah s. ibrahim al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 116122 (2018) 120 fig. 6. influence of feeding flow rate on the permeation flux at different feed temperatures and 35 g/l nacl feed solution. 4.3. effect of feed concentration figure (7) displays the relationship between the feed concentration and the permeation flux. the experimental tests were conducted at many feed concentrations (0, 15, 35, 70, and 100 g/l of nacl) and different feed flow rates (0.3, 0.7 and 1.07 l/min), while the feed temperature remained constant at 60 °c. the results show that the permeate flux decreased about 23.28% when the feed concentration increased from zero to 35 g/l and 24.91% with the increase of salt concentration from 35 to 100 g/l. the overall ratio of permeate reduction was reached to 42.4% when the feed salt concentration increased from zero to 100 g/l at 1.07 l/min feed flow rate. the low production flux can be explained by the impact of salt on the solution boiling point, the higher concentration of the saline solution leads to higher boiling point and thus reduced the amount of vapor flows across the membrane which led to decrease the permeate flux. fig. 7. effect of feed concentration on the permeation flux for solution at 60 °c feed temperature. 5. conclusions 1. the permeation flux improved with increasing feed temperature; when feed temperature raised by 20 degrees, the permeate flux increased by 116.56%, that indicates the feed temperature is quite controlling the permeate flux. 2. the permeate flux increased with increasing feed flow rate, the flux increased about 67.1% when the flow rate increased from 0.3 to 1.07 l/min. 3. the permeate flux decreased with increasing concentration of feed solution, the flux decreased about 42.4% when the feed salt concentration increased from zero to 100 g/l. 4. the percentage of salt rejection was reached about 99.98% even at high concentrations. notation tbp bulk permeate temperature tbf bulk feed temperature tmf membrane feed side temperature tmp membrane permeate side temperature cbf salt concentration at the bulk feed cmf salt concentration at the feed side m of membrane surface pº vapor pressure a,b,c constants of antoine’s equation t temperature salah s. ibrahim al-khwarizmi engineering journal, vol. 14, no. 2, p.p. 116122 (2018) 121 6. references [1] bahar, r., "conversion of saline water to fresh water using air gap membrane distillation (agmd)", ph.d. thesis. university of singapore, 2010. [2] yarlagadda, s., gude, v., camacho, l., pinappu, s. and deng, s, "potable water recovery from as, u, and f contaminated ground waters by direct contact membrane distillation process", journal of hazardous materials, 192, pp.(1388-1394), 2011. [3] al-obaidania, s., curcio, e., macedonio, f.,profio, g.,al-hinai, h. and drioli, e, "potential of membrane distillation in seawater desalination: thermal efficiency sensitivity study and cost estimation", journal of membrane science,323, pp.(85– 98), 2008. [4] eleiwi, f., ghaffour, n., alsaadi, a., francis, l.,and laleg-kirati, t, "dynamic modeling and experimental validation for direct contact membrane distillation (dcmd) process", desalination,384, pp.(1–11), 2016. [5] gryta m., "influence of polypropylene membrane surface porosity on the performance of membrane distillation process", journal of membrane science, 287, pp. (67-78), 2007. [6] cheng, d., gong, w., and li, n, "response surface modeling and optimization of direct contact membrane distillation for water desalination", desalination, 394, pp.(108– 122), 2016. [7] alkhudhiri, a., darwish, n., and hilal, n, "membrane distillation: a comprehensive review", desalination, 287, pp. (2-18), 2012. [8] sanmartino, j., khayet, m., and garcía-payo, m, "desalination by membrane distillation", book, university complutense of madrid, emerging membrane technology for sustainable water treatment, pp. (77-109), 2016. [9] cath, t., adams, v., and childress, a., " experimental study of desalination using direct contact membrane distillation: a new approach to flux enhancement", journal of membrane science, 228, pp. (5-16), 2004. [10] my, d., "membrane distillation application in purification and process intensification", msc thesis, asian institute of technology, school of environment, resources and development, thailand, 2015. [11] phungsai, p., "development of thermo philic anaerobic membrane distillation bioreactor", msc thesis, asian institute of technology school of environment, resources and development, thailand, 2013. [12] el-bourawi, m., ding, z., ma, r., and khayet, m., "a framework for better understanding membrane distillation separation process", journal of membrane science, 285, pp. 4–29, 2006. [13] banat, f., "membrane distillation for desalination and removal of volatile organic compound from water", ph.d. thesis, university of mcgill, canada, 1994. [14] dahiru,u., and khalifa, a., "flux prediction in direct contact membrane distillation", international journal of materials, mechanics and manufacturing, 2014. [15] camacho, l., dumée, l., zhang, j., li, j. and duke, m., "advances in membrane distillation for water desalination and purification applications", water,5, pp.(94– 196),2013. )2018( 116-122، صفحة 2د، العد14دجلة الخوارزمي الهندسية المجلمصالح سلمان ابراهيم 122 المباشر االتصال يغشاء التقطير ذ باستخداملمياة عالية الملوحة تحلية ا **نور اياد محمد امين *صالح سلمان ابراهيم الجامعة التكنولوجية*،**قسم الهندسة الكيمياوية/ yahoo.com2017nourayad@:البريد االلكتروني** الخالصة العالية الملوحة. تم دراسة تأثير المياهالمباشر في تحلية االتصال يفي هذا البحث تم عمل تجارب مختبرية لغرض التحقق من اداء غشاء التقطير ذ سطحية التغذية و معدل جريانها و تركيز األمالح. تم استخدام وحدة غشاء مسطحة ذو مساحة عوامل التشغيل المختلفة على األداء و منها درجة حرارة مياة ) معدل مسامية الغشاء. وجد ان نسبة %٧٨( ) مايكرون و٩٦السمك (، ) مايكرون٠٬٢٢حجم مسام (ي ) مع غشاء بولي تيترا فلوراثيلين التجاري ذ٢سم ١٦( و الماء البارد درجة مئوية )٦٥(ساعة عندما كانت حرارة المحلول الساخن .٢كغم/م) ١٧٬٢٧( اء النقي الناتجو معدل الم %٩٩٬٩ازالة األمالح اكبر من مئوية.) درجة ٢٠( تحسين وكريم وخالدة7079 al-khwarizmi engineering journal, vo prediction of process parameters roughness using tahseen fadhil ab khalida kadhim mansor *,**,*** department of production engineering and metallurgy / university of technology (received https://doi.org/10.22153/kej.2019.10.002 abstract multipoint forming process is an engineering concept which means that the working surface of the punch and produced as hemispherical ends of individual active elements (called pins), where each vertically displaced using a geometrically reconfigurable die tools saved precious production time. also expenses are saved. but the most important aspects of using such types of equipment this paper presents an experimental investigation of the effect of thickness and forming speed that affect the surface integrity for brass (cu zn 65 this paper focuses on the development of predict variance (anova), surface roughness has b rubber thickness and forming speed have been considered as model parameters. the mean surface roughness (ra) is used as response parameter to predict the surface roughness of multipoin generated, compared and evaluated to the proposed models obtained from experiments. taguchi algorithm was used to predict the forming parameters (blank holder, rubber thickness and forming speed) on product roughness in forming process of brass (cu zn 65 was used to find the optimum parameters that keywords: analysis of variance (anova), forming parameters roughness. 1. introduction multipoint forming (mpf) is a modern manufacturing technology for three sheet metal forming process. the idea of die of various shapes has been always attractive as a means of reduction costs of die design, since it would permit design iterations to be rapid and nearly cost free [1]. the effecting method for manufacturing metal product of 3d complex shapes is khwarizmi engineering journal, vol. 15, no. 2, june , (2019) p.p. 7079 process parameters that affecting on roughness in multipoint forming process using anova algorithm l abbas* karem mohsenyounis khalida kadhim mansor *** department of production engineering and metallurgy / university of technology *email: tfalani@yahoo.com ** email: karim_mohsen @yahoo.com *** email: kh_ak07@ yahoo.com (received 22 june 2018; accepted 18 october 2018) https://doi.org/10.22153/kej.2019.10.002 multipoint forming process is an engineering concept which means that the working surface of the punch and produced as hemispherical ends of individual active elements (called pins), where each pin can be independently, vertically displaced using a geometrically reconfigurable die. several different products can be made without changing tools saved precious production time. also, the manufacturing of very expensive rigid dies is reduced, expenses are saved. but the most important aspects of using such types of equipment are the flexibility of the tooling. an experimental investigation of the effect of three main parameters which are blank holder, rubber nd forming speed that affect the surface integrity for brass (cu zn 65-35) with 0.71 mm thickness. on the development of prediction models for estimation of the product quality. using urface roughness has been modeled. in the development of this predictive model, blank holder, rubber thickness and forming speed have been considered as model parameters. the mean surface roughness (ra) is used as response parameter to predict the surface roughness of multipoint forming parts. the data required has been to the proposed models obtained from experiments. used to predict the forming parameters (blank holder, rubber thickness and forming speed) ness in forming process of brass (cu zn 65-35) based on orthogonal array of l9 and used to find the optimum parameters that have effect on the product quality. analysis of variance (anova), forming parameters, multipoint forming process (mpf, surface forming (mpf) is a modern manufacturing technology for three-dimensional . the idea of forming always attractive as die design, since it to be rapid and manufacturing sheet complex shapes is sheet metal forming process. this use a matched solid die set that forms a cavity into which the sheet is displaced. sets may be needed to form a sheet metal parts. this process, to produce different shaped that must be required different dies. the design and manufacturing of punch and dies is work and must rely on the experience of and workers. the idea of shape has always been attractive as a means of reducing die design costs [ al-khwarizmi engineering journal on surface point forming process karem mohsenyounis ** department of production engineering and metallurgy / university of technology multipoint forming process is an engineering concept which means that the working surface of the punch and die is pin can be independently, everal different products can be made without changing the manufacturing of very expensive rigid dies is reduced, and a lot of the flexibility of the tooling. main parameters which are blank holder, rubber 35) with 0.71 mm thickness. the product quality. using analysis of een modeled. in the development of this predictive model, blank holder, rubber thickness and forming speed have been considered as model parameters. the mean surface roughness (ra) is t forming parts. the data required has been used to predict the forming parameters (blank holder, rubber thickness and forming speed) 35) based on orthogonal array of l9 and finally anova forming process (mpf, surface . this traditional process a matched solid die set that forms a cavity into which the sheet is displaced. sometimes, several to form a sheet metal parts. in different shaped of parts different dies. the design punch and dies is a costly work and must rely on the experience of designers of die forming of variable been attractive as a means of [2]. tahseen fadhil abbas al a schematic of a multipoint forming with a blank-holder is shown in figure (1) fig. 1. principle of multi point forming process [1]. a series of experiment have been carried out in design of experiments to investigate the effect of forming parameters such as blank holder, rubber thickness and forming speed on surface roughness. linfa peng et al (2006) [3] design the contact surface between the workpiece and the surfaces of the blank holder. two designs were developed to transition surface one is a bridge surface extension, and the flexible surface extension. these two approaches that used continuity type (g2) to transition the design surface with both reliable and effective. in this transition design surface, the applications gave manufactured the forming product with high quality products in (mpf). yajie liu et al (2016) [4] designed an original rigid flexible blank holder (fbh) device. models of finite element analysis (fbh) are established without used of blank holder (nbh); the simulation is applying with different bhf in forming spherical surface parts and then acquired the optimal bhf. the results indicate that fbh forming process ca effectively wrinkling defects, thickness distribution is more reasonable, sheet metal flow is more uniform, and distribute uniformly and the stress and strain are minimum. babak beglarzadeh (2017) [5] investigate a flexible method for forming a metal, multiis used to form initial size of 300 × 300 mm using aluminum alloy sheet 2024. finite elements were simulated through abaqus/explicit 6.14.1. through, increasing of elastic layer (cushion) hardness, the minimum required of elastic layer proliferates. furthermore, (bhf) increment has a direct relation with the enhancement in hardness of polyurethane layer. the multipoint forming process of aluminum al-khwarizmi engineering journal, vol. 15, no. 71 a schematic of a multipoint forming process holder is shown in figure (1). principle of multi point forming process [1]. a series of experiment have been carried out in design of experiments to investigate the effect of forming parameters such as blank holder, rubber thickness and forming speed on surface roughness. linfa peng et al (2006) [3] design the een the workpiece and the surfaces of the blank holder. two designs were developed to transition surface one is a bridge flexible surface extension. these two approaches that used continuity type (g2) to transition the design ace with both reliable and effective. in this transition design surface, the applications gave manufactured the forming product with highquality products in (mpf). yajie liu et al (2016) [4] designed an original rigid flexible blank holder models of finite element analysis (fbh) are established without used of blank holder (nbh); the simulation is applying with different bhf in forming spherical surface parts and then acquired the optimal bhf. the results indicate that fbh forming process can be release effectively wrinkling defects, thickness distribution is more reasonable, sheet metal flow is more uniform, and distribute uniformly and the stress and strain are minimum. babak beglarzadeh (2017) [5] investigate a flexible -point forming is used to form initial size of 300 × 300 mm using aluminum alloy sheet 2024. finite elements were simulated through abaqus/explicit 6.14.1. through, increasing of elastic layer (cushion) hardness, the minimum required a thickness of elastic layer proliferates. furthermore, (bhf) increment has a direct relation with the enhancement in hardness of polyurethane layer. the multipoint forming process of aluminum sheet are performed, and the comparisons of a forming process between simulation functions and experimental parts are applied, which establish that the aluminum products have the best shape accuracy and surface accuracy. a.a. tolipov et al (2017) [6] effect of process variable such as the force blank holder, elastic cushion thickness, radius of curvature and coefficient of friction on the performance of forming parts in a flexible multi point process the research was carried out a multipoint forming process using a blank holder in order to study the effects of the, dimpling, wrinkling forming force and reduction of thickness to determine the optimum value of these variables are performed to simulate the multipoint forming of hemispherical shapes using finite element modeling. the effects of pr variables on maximum deviation from thickness reduction, the target shape and wrinkling were estimate using the response surface methodology. tahseen fadhel abaas et al (2018) [7] investigated the achievement of a multipoint die with tools in square matrix and suitable blank holder. each pin in the punch holder can be a significant moved according to the die high and at different load that applied with spring with respect to spring stiffness. the results shows the reduction in setting time with respe point incremental forming process that lead to (90%). and also show during the forming process, the deformation of the interpolator formed work piece can induce a shape error and the blank holder can eliminate or reduce dimples in work-piece. they predict the optimum value of some process variable that effect on surface roughness and estimate the empirical equation that present the response value with respect to process variables. 2. experimental work 2.1. material and process samples of brass alloy (cu zn 65 thickness (0.7 mm) were used to perform the experiments (9-samples). the geometry of forming tool that used in this work is shown in figure (2). while the geometry of final product illustrated in figure (3). the experimental work was applied using oil lubricant on a c-tek three machine with rotational speed of (6000 rpm), feed of (10 m/min) to manufacturing the hem shape used as the a half khwarizmi engineering journal, vol. 15, no. 2, p.p. 7079 (2019) sheet are performed, and the comparisons of a ss between simulation functions and experimental parts are applied, which establish that the aluminum products have the best shape accuracy and surface accuracy. a.a. tolipov et al (2017) [6] investigated the effect of process variable such as the force of blank holder, elastic cushion thickness, radius of curvature and coefficient of friction on the performance of forming parts in a flexible multipoint process the research was carried out a multipoint forming process using a blank holder udy the effects of the, dimpling, wrinkling forming force and reduction of thickness to determine the optimum value of these variables are performed to simulate the multipoint forming of hemispherical shapes using finite element modeling. the effects of process variables on maximum deviation from thickness reduction, the target shape and wrinkling were estimate using the response surface methodology. tahseen fadhel abaas et al (2018) [7] investigated the achievement of a multipoint die matrix and suitable blank holder. each pin in the punch holder can be a significant moved according to the die high and at different load that applied with spring with respect to spring stiffness. the results shows the reduction in setting time with respect to traditional single point incremental forming process that lead to (90%). and also show during the forming process, the deformation of the interpolator formed workpiece can induce a shape error and the blank holder can eliminate or reduce dimples in the they predict the optimum value of some process variable that effect on surface roughness and estimate the empirical equation that present the response value with respect to process experimental work material and process samples of brass alloy (cu zn 65-35) with thickness (0.7 mm) were used to perform the samples). the geometry of forming tool that used in this work is shown in figure (2). while the geometry of final product perimental work was applied using oil tek three-axis (km-80d) cnc machine with rotational speed of (6000 rpm), feed of (10 m/min) to manufacturing the hem-spherical shape used as the a half-die. the mechanical tahseen fadhil abbas al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 7079 (2019) 72 properties and chemical composition of brass (6535) is illustrated in tables (1 & 2). the shape of forming tools that used in this work is square tool steel (15x15x80 mm) while the tip of tool is hemspherical shape. three types of blank holder was with different size and shape that illustrated in figure (4) while multi-point forming die and the final nine products are illustrated in figure (5). table 1, mechanical properties for brass sheet (isocu zn 65-35 426/1). material tensile strength mpa modulus of elasticity gpa poissons ratio elongation % on 50 mm g.l. vickers hardness hv iso 65/35 brass ’o’ exp. 230 0.375 31.5 100≤ cu zn 35 426/1 iso 230 110 0.33 56 90≤ table 2, chemical composition of brass sheet (isocu zn 65-35 426/1). material zn% pb% sn% p% mn% fe% ni% si% al% cu% brass exp. 35.23 0.007 0.001 0.007 0.000 0.021 0.001 0.001 0.002 64.7 iso 35.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 65.0 forming tool fig. 2. geometry of the forming tool (all dimension in (mm)). tahseen fadhil abbas al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 7079 (2019) 73 fig. 3. geometry of part and cnc-part program. (all dimension in (mm)). (a) (b) (c) fig. 4. types of blank holder that used in this work. tahseen fadhil abbas al fig. 5. the experimental setup and nine the measurement device that used in this work is surf tester (mahr pocket surf test) (6). this device was used to measure the surface roughness of the formed surface, the forming surface was measured after cut off to simplest the measurement procedures at three different positions and arithmetic mean surface roughness (ra) are used as output parameters to surface quality of multipoint forming fig. 6. surface roughness measurement device 2.2. plan of experiments an important stage in response surface model generation by anova is the planning of experiments. the parameters which has a al-khwarizmi engineering journal, vol. 15, no. 74 the experimental setup and nine-samples. the measurement device that used in this work (mahr pocket surf test) device, figure (6). this device was used to measure the surface , the forming surface was measured after cut off to simplest the procedures at three different positions and arithmetic mean surface roughness to evaluate the forming product. surface roughness measurement device. an important stage in response surface model generation by anova is the planning of experiments. the parameters which has a significant influence on surface quality was identified they by blank holder types, cushion thickness and forming speed in multi forming process. figure (7) present the problem solving and the analysis of data. fig. 7. define the research problem and their analysis. uses a special design of orthogonal arrays with a small number of experiments taguchi method to study the entire parameter space. the methodology of taguchi for three factors (blank holder, elastic cushion thickness and forming speed) at three levels for each is used to applied the experiments. to define the nine trial conditions, is used the degrees of freedom required for the study is six and taguchi orthogonal array. the levels and process parameters are illustrated in table (3). the average response and replicated twice values for each of the process designs of nine trials are used. table (4) illustrated the present work and the test results, and figures (8, 9 and 10) represent the relationship between experimental data. table 3, levels and parameters parameters unit blank holder type (b) rubber thickness(r ) mm speed (s) mm/min khwarizmi engineering journal, vol. 15, no. 2, p.p. 7079 (2019) significant influence on surface quality was identified they by blank holder types, cushion thickness and forming speed in multi-point forming process. figure (7) present the problem solving and the analysis of data. define the research problem and their uses a special design of orthogonal arrays with a small number of experiments taguchi method to re parameter space. the methodology of taguchi for three factors (blank holder, elastic cushion thickness and forming speed) at three levels for each is used to applied the experiments. to define the nine trial conditions, is used the degrees of freedom quired for the study is six and taguchi’s (l9) orthogonal array. the levels and process parameters are illustrated in table (3). the average response and replicated twice values for each of the process designs of nine trials are used. table the present work and the test results, and figures (8, 9 and 10) represent the relationship between experimental data. lev.1 lev.2 lev. 3 1 2 3 2 4 6 mm/min 2 5 10 tahseen fadhil abbas al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 7079 (2019) 75 table 4, taguchi’s l9 orthogonal array and response value parameters response value exp. no blank holder type rubber thickness mm speed mm/min surface roughness µm ra1 ra2 ra3 rav 1 1 1 1 1.11 1.13 1.15 1.13 2 1 2 2 1.30 1.27 1.27 1.28 3 1 3 3 1.02 1.09 1.06 1.0567 4 2 1 2 0.50 0.58 0.57 0.55 5 2 2 3 0.99 1.01 1.01 1.0033 6 2 3 1 1.80 1.71 1.82 1.7767 7 3 1 3 0.80 0.84 0.79 0.81 8 3 2 1 0.55 0.54 0.54 0.5433 9 3 3 2 0.81 0.74 0.77 0.7733 fig. 8. the relationship of average roughness with respect to process parameters. fig. 9. the relationship of mean of mean for each process variable. 2 4 0 5. 1.0 1 6 2 3 1.5 ughnessor egareva redloh knalb t rebbu nickr essh uuuurrrr ffffaaaacccceeee ppppllllooootttt ooooffff aaaavvvveeeerrrraaaaggggeeee rrrroooouuuugggghhhhnnnneeeessssssss &&&& bbbbllllaaaannnnkkkk hhhhoooollllddddeeeerrrr ;;;;ssss rrrruuuubbbbbbbbeeeerrrr tttthhhhiiiicccckkkknnnneeeessssssss 2 5 0.5 0.1 2 10 4 6 1.5 ughnessor egareva rebbur t ssenkich dpees uuuurrrr ffffaaaacccceeee ppppllllooootttt ooooffff aaaavvvveeeerrrraaaaggggeeee rrrroooouuuussss hhhhnnnneeeessssssss &&&& rrrruuuubbbbbbbbeeeerrrr tttthhhhiiiicccckkkknnnneeeessssssss ;;;; ssssppppeeeeeeeeddddgggg 2 5 .50 1.0 1 01 2 3 5.1 ave age rr ssenhguo redloh kblan pees d uuuurrrr ffffaaaacccceeee ppppllllooootttt ooooffff aaaavvvveeeerrrraaaaggggeeee rrrroooouuuugggghhhhnnnneeeessssssss &&&& bbbbllllaaaannnnkkkk hhhhoooollllddddeeeerrrr ;;;; ssssppppeeeessss ddddeeee 321 1.2 1.1 1.0 0.9 0.8 0.7 642 1052 blank holder mm mm ee ee aa aa nn nn oo oo ff ff mm mm ee ee aa aa nn nn ss ss rubber thickness speed mmmmaaaaiiiinnnn eeeeffff ffffeeeecccc ttttssss ppppllllooootttt ffffoooorrrr mmmmeeeeaaaannnnssss data means tahseen fadhil abbas al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 7079 (2019) 76 fig. 10. the relationship of response value with respect to process variables. 3. prediction of process parameters using taguchi’s algorithm to predict the effect of each parameters on the response value and to estimate the empirical equation contribute between each process parameter in second order as illustrated in equation (1) to optimize the present work with present of confidence (r=86.53%), from the given data (blank holder (b), rubber thickness (r) and forming speed (s)) with respect to surface roughness. table (5) represents the final prediction value using taguchi’s algorithm, while table (6) represent the analysis of variance using anova algorithm. rav =0.5617+0.2034b+0.7165r–0.4155 s-0.1778 b2 -0.03105 r2+0.0081s2-0.116br +0.1321bs ... (1) table 5, prediction of process parameters with respect to response value using empirical equation process parameters average response exp. no. blank holder type rubber thickness mm speed mm/min surface roughness µm rav 1 1 2 5 0.87037 2 1 2 10 0.95925 3 1 4 2 1.26481 4 1 4 10 1.07148 5 1 6 2 1.52481 6 1 6 5 1.24259 7 2 2 2 1.10704 8 2 2 10 0.91370 9 2 4 2 1.21926 10 2 4 5 0.93703 11 2 6 5 1.19704 12 2 6 10 1.28593 13 3 2 2 0.70592 14 3 2 5 0.42370 15 3 4 5 0.53592 16 3 4 10 0.624815 17 3 6 2 1.07815 18 3 6 10 0.884815 1.50 1.25 1.00 0.75 0.50 3.02.52.01.51.0 1.50 1.25 1.00 0.75 0.50 65432 blank holder * rubber thick blank holder * speed2 bbbb llll aaaa nnnn kkkk hhhh oooo llll dddd eeee rrrr rubber thick * speed2 rrrruuuu bbbb bbbb eeee rrrr tttthhhh iiii cccckkkk 2 4 6 thick rubber 2 6 10 speed2 mm mm ee ee aa aa nn nn oo oo ff ff aa aa vv vv ee ee rr rr aa aa gg gg ee ee rr rr oo oo uu uu gg gg hh hh nn nn ee ee ss ss ss ss iiiinnnntttteeeerrrraaaacccc tttt iiiioooonnnn ppppllllooootttt ffffoooorrrr aaaavvvveeeerrrraaaaggggeeee rrrroooouuuugggghhhhnnnneeeessssssss fitted means tahseen fadhil abbas al table 6, analysis of variance using anova algorithm source df adj ss blank holder 1 0.84043 rubber 1 0.57484 speed 1 0.16820 second order blank h*blank h 1 0.18963 rubber*rubber 1 0.03276 speed*speed 1 0.25852 2-way interaction blank h*rubber 1 0.00038 blank h*speed 1 0.06678 rubber*speed 1 0.07449 error 17 1.5834 total 26 2.61191 level of confidence (f-value) =95% =0.95 level of significance (p-value) =5% = 0.05 1p-value p < 0.05 → significant p > 0.05 → nonsignificant 2fisher value (f-value) f > ft (from table) critical tabulated ft=4.4513 percent of contribution % = ��� �� ��� ��� percent of contribution % blank holder =53.075 % rubber thickness =36.301 % speed of forming =10.622 % 4. results and discussion the results of this work is to investigate the effect of various forming parameters (blank holder (b), rubber thickness (cushion) (r) and forming speed (s)) with respect to surface roughness that occurs on the forming parts of brass (cu zn 65-35) using multi-point forming process. the figures were result from the experimental work using anova algorithm that illustrated in figures (7and 8). the effects of two input parameters represents in each curve in otherwise the parameter was kept constant. the effect of blank holder on the minimum surface roughness at the different cushion thickness and forming speed were used. in this work, with respect to the range of forming parameters used, explain that at the rubber thickness (r=2mm) and using blank hol (3) and forming speed of (s=2mm/min) that gives minimum surface roughness (r as shown in figures (9) and table (5). while al-khwarizmi engineering journal, vol. 15, no. 77 analysis of variance using anova algorithm analysis of variance adj ss f-value p-value 0.84043 40.61 0.000 0.57484 27.78 0.000 0.16820 8.13 0.011 0.18963 9.16 0.008 0.03276 1.58 0.225 0.25852 12.49 0.003 0.00038 0.02 0.893 0.06678 3.23 0.090 0.07449 3.60 0.075 1.5834 2.61191 value) =95% =0.95 value) =5% = 0.05 (from table) critical tabulated �� ��� �� ∗ 100 % ... (2) the results of this work is to investigate the effect of various forming parameters (blank holder (b), rubber thickness (cushion) (r) and forming speed (s)) with respect to surface roughness that occurs on the forming parts of point forming process. the figures were result from the experimental work using anova algorithm that illustrated in figures (7and 8). the effects of two input parameters represents in each curve in otherwise the parameter was kept constant. the effect of blank holder on the minimum surface roughness at the different cushion thickness and forming speed were used. in this work, with respect to the range of forming parameters used, explain that at the rubber thickness (r=2mm) and using blank holder type (3) and forming speed of (s=2mm/min) that gives minimum surface roughness (ra=0.42370), as shown in figures (9) and table (5). while figure (10) presents the variance of average roughness value with respect to three process parameters. the final empirical model of each forming parameters with respect to average surface roughness using taguchi’s algorithm. percentage effect of blank holder types, rubber thickness and forming speed with respect to minimum surface roughness was (53.075, 36.301 and 10.622 shown in figure (11). fig. 11. the contribution of process parameters that effect on surface roughness. 5. conclusion the current research reviewed some important aspects related with surface roughness on forming of materials with special emphasis in brass-alloy. based on the results of the present work of surface roughness in multi process using anova algorithm, the following conclusions can be drawn: khwarizmi engineering journal, vol. 15, no. 2, p.p. 7079 (2019) �� � � � � � � � � � figure (10) presents the variance of average roughness value with respect to three process parameters. the final result is estimate the empirical model of each forming parameters with respect to average surface roughness using taguchi’s algorithm. percentage effect of blank holder types, rubber thickness and forming speed with respect to minimum surface roughness was 10.622) % respectively as the contribution of process parameters that effect on surface roughness. the current research reviewed some important aspects related with surface roughness on forming of materials with special emphasis in alloy. based on the results of the present work of surface roughness in multi-point forming process using anova algorithm, the following conclusions can be drawn: tahseen fadhil abbas al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 7079 (2019) 78 1. in multipoint forming process, the process parameters (blank holder types, rubber thickness and forming speed) is the main factors that effect on surface roughness. 2. the results of anova algorithm and the effectiveness experiments data that the developed empirical models for the output responses provide the predicted values and shows an excellent fit of these surface roughness factors that are close to the experimental values, at (r=86.53%)% confidence level. 3. the optimum value of roughness that result from this work using anova is equal to (ra=0.42370) when using blank holder type (3) and cushion thickness (r=2mm) and at forming speed of (s=5mm/min). 4. medium forming speed gave the best surface roughness, because it give enough time for the metal to reorganize the atoms and thus reduce the strength of the metal resistance to the forming force, the effectiveness range up to (10.622%). 5. low cushion thickness takes the best surface roughness because the contact area between forming tool and blank is minimum that occurs best result, the effectiveness range up to (36.301%) 6. the blank holder type (3) gave the best surface roughness up to (53.075%). 6. references [1] m.z. li, z.y. cai, z. sui and q.g. yan, multi-point forming technology for sheet metal, elsevier science, journal of materials processing technology 129 333-338, 2002. [2] abdulkareem jalil kadhim, and mostafa imad abbas, three-dimensional experimental and numerical simulation of sheet metal forming process based on flexible multipoint die, international journal of mining, metallurgy & mechanical engineering (ijmmme) volume 2, issue 1, 2014. [3] linfa peng xinmin lai, mingzhe li, transition surface design for blank holder in multi-point forming, elsevier science, international journal of machine tools & manufacture 46, 1336–1342, 2006 [4] yajie liu, mingzhe li and feifei ju, research on the process of flexible blank holder in multi-point forming for spherical surface parts, springer, int j adv manuf technol, 89:2315–2322,2017. [5] babak beglarzadeh, an experimental and numerical study of forming parameters affection on multi-point deep drawing process, international journal of advanced and applied sciences, 4(1), pages: 90-95, 2017. [6] a a tolipov, a elghawail, m abosaf, s shushing, d pham and k essa, experimental research and numerical optimisation of multi-point sheet metal forming implementation using a solid elastic cushion system, conference paper, department of mechanical engineering, school of engineering, university of birmingham,uk, july 2017. [7] tahseen fadhel abaas, karem mohsenyounis and khalida kadhim mansor, die design of flexible multi-point forming process, al-khwarizmi engineering journal, vol. 14, no.2, june, p.p. 2229, 2018. ���� ���س �� )2019( 70-79، ! �� 2د، ا�������15 ا���ارز ا������� ا���� 79 �ؤ�ر ��� ��و � ا��ط� �����دام ����ن ����رات ����� ا�����ل ���دد ا� ��ط ا��� �وارز��� �!��ل ا�����ن ***� )ور ��ظم ���دة ** �و س �!�ن �ر�م * ���س $�#ل �!��ن *،**،***� �� ��� / وا����دن ا����ج ھ��� ا��!� � ��� ا� tfalani@yahoo.com * :ا��!�#و�% ا�$#" karim_mohsen@yahoo.com : ا��!�#و�% ا�$#" ** kh_ak07@yahoo.com "#$ا� :ا��!�#و�% *** �ا��ـ#!ـ &� د ا��'!���2 1 د 0#و"� /.�#ة �,+ م ھ ا��(�ط ��& ا� 89 �7��6 ام ��5 31 ي و�,%3 ��! ن !'�7 %��" %� 1: ھ�; �+�����< %< �3)� � � �(#ة و� ? ع) � ��ر( &�0& 1 ة ;'! �+���ab � $� �3 89 ا��#اد ;'!�3@ وا��% "! ن > &!'7 ، #�.; d"#21 ط @���e; 2!��1 د ��� ع �2 ا����ذج i ا�� ة ��� "hدي ا�: ;(3�& ز�2 ا����ج وا��% ;� � دة � �!�ن� #"�� lا�2 ا���3��ت واطj� ا�!3,� و �����ت ����#و�� ، 3(��5 �, @ا���ج 2� "m; %وا�� ��3�1 %< �� �d ;. ا��'!�& ا��� ات ا�� �6)n; ���� on$ا ا�pھ %<q &�3�1�� ا��'! %< � �aات ر#�.�� �rbr #�r)sا���� t$u���v ط$(� ا���9ط ، � ع &��!� ا�$#اص 7 �v ) و�1#� 3�1�� ا��'!$ � s;89 ا��� دة ا� �٠.٧١�3(31: �.( � د"& ;�6��% ��9 "# � دة ا� 89 #" 31: ;9 m�3�& ا��$�"2 ;� ;! "2 ا�� د"& ا�#"�?% �� دة ا� 89 و�7��6. >% ھpا ا�$on ;� ا��0#n; ��� ام \ ارز ��o ;� ا\�$�ر ا�$����ت ا��39 7� و�(�ر��+� �i ا����sa ا���3�� و^ �ب ^ &��# ���7 $� �� ع ا��t$u و��v ط$(� ا���9ط و�1#� 3�1�� ا��'!r�;و d7�9ار ا�� ) ��3��3� #�.�� &0. �� %_ 0�; ����#ات ا���3�� ;� ا��6 ام \ ارز.�� 2��6)�n�,eا� t$u� ،&�31: ا�� '6� v�� ( ط$(� ا���9ط و�1#� 3�1�� ا��'! �n� 7#اص ,/ &�!'�� ��n9 ٣٥٦٥(ا� ( �< ,e��7��6 ام )l9 (���6#��ت ا���3 :31 #�r�; @� #�.�� #u0د ا�� .وا" (microsoft word \315\323\344 \332\341\355, \307\315\343\317 38 44) al-khwarizmi engineeringjour nal al-khwarizmi engineering journal, vol. 15, no. 3, sptember, (2019) p. p. 3844 the effect of wind velocity on the suppression of composite wing airfoil naca 0012 hassan ali kadhem* ahmed abdul hussein** *,**department of mechanical engineering/ college of engineering/ university of baghdad/ iraq *email: hali2013201359@gmail.com **email: dr.ahmed.ali@coeg.uobaghdad.edu.iq (received 29 april 2019; accepted 19 june 2019) https://doi.org/10.22153/kej.2019.06.007 abstract the first studies on shocks and vibrations were carried out at the beginning of the 1930s to improve the behavior of buildings during earthquakes. vibration tests on aircraft were developed from 1940 to verify the resistance of parts and equipments prior to their first use. flutter is a well-known example of dynamic aero elasticity, where when oscillation of structure interacted with unsteady aerodynamic forces the flutter will occur. vibration on any structure without damping means that self-harmonic oscillation will occur, and in most cases the oscillation may start to increase until structural failure. this behavior is very similar to resonance phenomena if only the oscillation is being studied as a vibration case. in vibration suppression, the active vibration control is one of the more effective technique which is used for attenuating bad effects of disturbances on structure. in this work, two different composite wings have been used; one of them is made of glass-fiber random matt and the other is made of woven ({0/90} glass-fiber). the proportionalintegral-derivative (pid) control is employed here for studying the suppression of active vibration wing affected by wind velocity flow through wind tunnel in the laboratory of mechanical engineering department at the university of baghdad. piezoelectric (pzt ) transducers are used as sensors and actuators in vibration control systems. the attack angle was 10 degrees and three different velocities (15, 20, 35 m/s) have been taken to show their effect on the wings vibrations suppression. is noticed that the suppression of the wing amplitude is reduced when the wind velocity increases for both woven and random composite wing matt. this is happened due to the vortex which has became more violent with the increase in wind velocity. it is concluded that the composite woven wing has high resistance more than the composite random wing. also, the maximum control amplitude of woven matt is 1.9 cm and the damping is about 33% at 25 m/s wind velocity while the amplitude is 2.22 cm and the damping is about 53% at 10 m/s wind velocity for random wing. keywords: wind velocity, piezoelectric, naca 0012, proportional-integral-derivative control. 1. introduction all the mechanical systems suffer external effects like structure moves through the air. this motion will cause aerodynamic loads which leads to deformations of the structure. the deformation in turn has an impact on the airflow, thus changing the aerodynamic loading. apparently, there is a closed loop of aerodynamic and structural interactions and depending on the properties of the structure and the airflow, different methods of controlling have been used with many applications to give the reader enough knowledge about it. different works in the literature were studied the active vibration control techniques [12]. song z, li f. in [1] used derivative of velocity and proportional feedback on two different types of controllers in vibration were used with pzt as sensors and actuator. the ability of suppression of composite plate used for aero elastic analysis is studied. no experimental tests had been presented and the modal analysis of tested model was formulated by matlab codes. results hassan ali kadhem al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 3844 (2019) 39 show that proportional regulator has high effectiveness in vibration suppression with 31% and 25% for free and forced responses respectively. in [2], composite plate with pzt is used to perform controlling loop. the study is aimed for evaluating the performance of an active regulator for suppression of undesired vibrations. this suppression is carried out via controlling loop and pzt as sensors and actuators totally formulated in finite element (fe) environment. numerical simulation had been done in ansys environment for composite smart plate equipped with pzt. besides fe model, real model is fabricated and tested experimental for vibration suppression. about 59% of overall model vibration is suppressed with good agreement between both experimental and numerical responses. pzt in [3] is used to sense the strain of flexible aluminum cantilever beam and fed it back to regulator loop for actively attenuation of its free oscillation. finite element simulation is performed besides experiments to check the acceptance of measurements. using national instruments (ni), crio 9022 in lab view is used in controlling loop. results exhibit high level of agreement between both tests. high performance of regulator feedback to attenuate about 49% of free oscillation is noticed. the control law has demonstrated 53.91% and 62.5% reduction in vibration for the first and second mods respectively. m. kerboua, et al in [4] proposed a method called "passive piezoelectric vibration shunt control". in the beginning, the numerical solver is utilized in order to estimate best design and position of pzt. maximum attenuation that was satisfied in oscillation was leveled by percent of forty two from bending oscillation. the results shown that the efficiency of the control is sensitive to the pzt patch location and the accuracy of the shunt circuit is being tuned. active flutter suppression is tested for a base profile model of delta wing [5]. the aimed is to provide a numerical approximate to improve the active flutter damping methodology for a fin. the fin was a cantilever aluminum plate like structure with surface enslaved pzt pieces. surface enslaved pzt pieces which behave as actuators. as a result, the closed loop of the system appeared a transition from a stable condition to unstable condition about 88.6 m/s for single input single output model with 5.4 % improvement and 93.7 m/s to multi input multi output model with 11.4 % improvement. the work in [6] is focused on introducing general implementation on attenuation of oscillated body. tested body is a beam fixed from one end and free from another equipped with pzt. first group of pzt were used to measure feedback signal, and another group were for applying controlling force. such tested model is used in some aerospace applications in which system stability is an important issue. linear quadratic controller is used as a controlling technique, where excitation of three millimeter is applied at free end of tested model. linear quadratic regulator is utilized to run regulating process with high performance. results show high degree of effectiveness in using linear quadratic regulator for attenuation of system oscillation where about 70% of free body oscillation is eliminated with control on mode. the study of wind velocity change and show their effect on forced suppression composite wing is a new contribution and also to be ensure of control system response. the results showed the ability of control system to damping the vibration. the structure of this paper starts with explains about wings which is used in this paper in section 2. then show the measurement device used in the experimental work in section 3. section 4 explains lab view program. section 5 explains experimental description. section 6 explains the results discussion, finally conclusion in section 7. 2. wings model the aircraft wing has transformed from the wooden and fabric twin-wing set up of the wright brothers’ flyer, to the composite materials used in the latest models coming off the production line today from the likes of boeing and airbus. aircraft designer have designed several wing types that have different aero dynamic properties. two composite wings were fabricated by skinning foam model. the foam model was made by cutting the foam via hot wire by passing the hot wire around the aluminum airfoil's shape getting from cnc machine as shown in fig 1. the two foam models were skinning by glass-fiber matt one with random and the other with woven ({0/90} glass-fiber). two layer of glass-fiber matt for each random and woven every layer were coated by mixture of resin, thickener powder and hardener. the two wig dimensions were as shown in fig 2. hassan ali kadhem al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 3844 (2019) 40 fig. 1. the hot wire device. fig. 2. the dimension of the device. 3. measurements device 3.1 piezoelectric transducer in this study, an electrical transducer ppa1001 is used as sensor and actuator as well. mid ́ piezo (standard products, usa) utilize its piezo protection advantage (ppa) to protect the piezo ceramic wafers. the ppa1001 is a single layer product recommended for actuating, energy harvesting and sensing applications. it also exhibits good performance as a resonant actuator [7]. ppa-1001 is presented in fig 3. fig. 3. ppa-1001 transducer with its dimension in (mm). 3.2 compact daq-9178 chassis (national instruments) it is an 8-slot (national instruments. usa) compact daq, usb chassis as shown in fig 4 is designed for mixed-measurement, small, portable test systems. it combines sensor measurements with voltage, current, and digital signals to create custom mixed system with simple usb cable back to personal computer [8]. 3.3. analog input (ni 9215) module compatible with ni compact-daq chassis contains four simultaneous sampled analog input channels. channel to earth ground hassan ali kadhem al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 3844 (2019) 41 double isolation barrier with nist-traceable calibration are included for system safety and noise filtering respectively. also, high range of voltage is available common mode. range of analog input is ±10v, 100ks/s per channel with 16-bit sampling rate resolution [9]. ni 2915 is designed to work within temperature range of (-40 ~ 70). ni 9215 is one of national instrument products and is presented in fig. 5. fig. 4. ni compact daq -9178. fig. 5. ni 9215analog input voltage. 3.4 signal amplifier two signal amplifiers are used for actuators. the devices used in this work are high voltage inverted operational amplifier (model 2205.usa) presented in fig 6. each amplifier has the ability to amplify voltage up to ±500 v, output current range and bandwidth are ±80 ma and 75 khz with 3 db respectively with maximum output power of 40 w. safety of measurements against overloading the actuator was provided by such amplifier to protect both amplifier circuit & pzt from any damage caused by high input voltage or power [10]. fig. 6. signal amplifier. 4. labview program the active control program developed in labview and it used to apply active vibration [14]. labview contains an inclusive set of tools for storing data, acquiring, and analyzing [15]. in lab view program the signal input is received, processing and then sent as output signal at step time of 0.001 s to avoid shifting between the signals input and output [11]. the parameters (gain k, proportional gain kp, and integral gain ki) of the pid control must be adjusted to have suitable response against the signal of the piezo sensor. by try and error method, the magnitude of three parameter has been tested and the best value of the parameter is used in labview and that best values of the parameters were (kd = 6, kp=1, ki=0.01). a block diagram of the controller that used in this work is presented in fig. 7. hassan ali kadhem al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 3844 (2019) 42 fig. 7. block diagram of the controller used in this work. 5. experimental description the experimental system used in this work shown clearly in fig 8. the displacement responses of tested wing is sensed as voltage by piezoelectric, then forwarded this voltage to an analog input (ni 9215) which is used for noise filtering and acquiring data. however, by importing the relation between sensed voltage and displacement, voltage will be converted to its real value in labview through daq which is used to convert sensed signal from analog to digital signal. the output actuators' signals are simultaneously sent through daq to analog output card. then the controlling actuators' signals are sent to high voltage amplifier to drive the piezoelectric actuators which will act by opposite action to wing vibration to damping the vibration of the wing. fig. 8. the diagram of experimental active vibration control. 6. results and discussion it has been noticed that the suppression of the wing amplitude is reduced when the wind velocity increases for both woven and random composite wing matt as it compares with free amplitude response. this happens due to the vortex which becomes more violent at the increase of wind velocity as shown in fig. 9 and fig. 10. hassan ali kadhem al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 3844 (2019) 43 fig. 9. relation between wind velocity and controlling amplitude. fig. 10. relation between wind velocity and controlling amplitude. 7. conclusion the amplitude of control response increases when the wind velocity increases for both woven and random composite wing matt. the composite woven wing has high resistance more than composite random wing. the maximum control amplitude of woven matt is 1.9 cm and the damping was about 33% at 25 m/s wind velocity while it was 2.22cm and the damping was about 53 % at 10 m/s wind velocity for random wing. 8. reference [1] song, z li f. “active aeroelastic flutter analysis and vibration control of supersonic composite laminated plate”, composite structures, vol. 94, pp. 702–13, 2012. [2] xingjian dong, zhike peng, lin ye, hongxing hua and guang meng. “performance evaluation of vibration controller for piezoelectric smart structures in finite element environment”, journal of vibration and control, vol. 20, 2014. [3] riessom, w rao, p scholar, pg krishina, p gangadharan, k v. “strain feedback active vibration control of smart cantilever beam”, vol. 5, pp. 113-122, 2014. [4] kerboua, m megnounif, a benguediab, m benrahou, kh kaoulala, mf. “vibration control beam using piezoelectric-based smart materials”, composite structures, vol. 123, pp. 430-442, 2015. [5] fatih, k.“active flutter suppression of a smart fin”, school of natural and applied sciences, middle east technical university, turkey, 2008. [6] djojodihardjo, h jafari, m wiriadidjaja, s ahmad, ka. “active vibration suppression of an elastic piezoelectric sensor and actuator fitted 152 cantilevered beam configurations as a generic smart composite structure”, composite structures, vol. 132, pp. 848-863, 2015. [7] ppa-1001, data sheet, mide co. ltd., ppaseries 2016. [8] national instrument, “data sheet of compact daq-9178 chassis”, usa, 2014. [9] national instrument, “data sheet of daq-ni 9215”, usa, 2014. [10] trek inc., “operator’s manual, model 2205”, piezo driver/power amplifier", usa, 2013. [11] national instrument, “lab view-control design user manual”, 2010. [12] sebastian heinze. “aeroelastic concept for flexible aircraft structre”, aeronautical and vehicle engineering royal institute of technology stockholm, sweden, 2007. [13] sinusoidal vibration: second edition volumechristian lalanne copyright 0 2009, isteltd [14] ghada adel aziz. “simulation model of wind turbine power control system with fuzzy regulation by mamdani and larsen algorithms”, al-khwarizmi engineering journal,vol. 13, no. 1, pp. 5161 2017. [15] omar farouq lutfy and maryam hassan dawood. “model reference adaptive control based on a self-recurrent wavelet neural network utilizing micro artificial immune systems” al-khwarizmi engineering journal, vol. 13, no. 1, pp. 107 122 2017. )2019( 3844، صفحة 2د، العد15دجلة الخوارزمي الهندسية المجلم حسن علي كاظم 44 naca 0012 تأثير سرعة الرياح على تخميد أهتزاز جناح مركب ذو بروفويل نوع حسن علي كاظم* احمد عبد الحسين علي** *،**قسم الهندسة الميكانيكية/ كلية الهندسة/ جامعة بغداد gmail.com2013201359hali@*البريد االلكتروني: dr.ahmed.ali@coeg.uobaghdad.edu.iq**البريد االلكتروني: الخالصة لتحسين سلوك المباني أثناء الزالزل. تم تطوير اختبارات االهتزاز على ١٩٣٠واالهتزازات في بداية أجريت الدراسات األولى حول الصدمات للتحقق من مقاومة األجزاء والمعدات قبل استخدامها ألول مرة. ضاهرة الرفرفة هو مثال معروف على المرونة الديناميكية الهوائية ١٩٤٠الطائرات منذ عام ب الهيكل مع القوى الديناميكية الهوائية غير المستقرة ، سوف يحدث الرفرفة. عندما يؤثر االهتزاز على أي هيكل دون التخميد فهذا ، حيث عندما يتفاعل تذبذ كان الرنين إذايعني أن التذبذب الذاتي التوافقي سيحدث ، وفي معظم الحاالت قد يبدأ التذبذب في الزيادة حتى الفشل الهيكلي. يشبه هذا السلوك ظواهر السيطرة النشطة على االهتزاز هي تقنية فعالة لتخميد االهتزاز وكذلك تقليل التاثيرات الغير مرغوبة الناتجة من .التذبذب فقط قد درس كحالة اهتزاز حيث صنع الجناح االول من االضطراب المؤثر على الهيكل الميكانيكي .هناك نوعين من االجنحة المصنوعة من المواد المركبة تم أستخدامها في هذا البحث pidظام سيطرة نوع مادة الفايبركالس ذات الحصيرة العشوائية توزيع االلياف وصنع الجناح الثاني من مادة الفايبركالس المتعامدة توزيع االلياف .أسنخدم ن ي مختبر الهندسة الميكانيكية / جامعة بغداد. أستخدمت لدراسة تخميد االهتزاز النشط والناتج عن سرعة الرياح حيث وضع الجناح داخل نفق هوائي موجود ف م/ثا لمعرفة ٣٥الى ٢٥الى ١٥درجة في حين تم تغير السرعة من ١٠قطع كهروضغطيه في نظام السيطرة كمتحسس ومؤثر. زاوية الهجوم ثبت على تقل عند زيادة سرعة الرياح لكال الجناحين وذلك بسبب كون الدوامات تأثير سرعة الرياح على تخميد االهتزاز. كانت النتائج أن تخميد سعة اهتزاز الجناح ز أكبر من الجناح الهوائية المتكونة حول الجناح ستكون أعنف كلما زادت سرعة الهواء . كما لوحظ أن الجناح المصنوع من ألياف متعامدة لدية مقاومة أهتزا م/ثا بينما ٢٥بالنسبة لالهتزاز الحر للجناح عند السرعة %٣٣سنتيمتر ومقدار التخميد ١٫٩لياف االخر وكان مقدار أكبر سعة مخمدة للجناح المتعامد اال م/ثا . ١٠بالنسبة لالهتزاز الحر للجناح عند السرعة %٥٣سنتيمتر والتخميد ٢٫٢٢كانت سعة االهتزاز المخمد characterization of metal dispersion of some al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 5, no. 3, pp 77–86 (2009) characterization of metal dispersion of some naphtha reforming catalysts by methylcyclohexane dehydrogenation reaction ahmed j. ali *ameel mohammed rahman *department of biochemical engineering/ al-khwarizmi college of engineering/ university of baghdad (received 29 july 2008 :accepted 2 june 2009) abstract the dispersion of supported pt and pt–ir reforming catalysts have been studied, after treatment with oxidative and reducing atmosphere. methylcyclohexane dehydrogenation reaction in the absence of hydrogen was used as a test reaction. an attempt was made to relate the behavior of the catalysts upon subject to reaction, to the dispersion of the same type of catalysts upon treatment with similar atmosphere and temperatures which appeared in literature. the total conversion of reaction can be explained by a change in metal dispersion. thus, methylcyclohexane dehydrogenation reaction appears to be a really “structure sensitive” reaction. the toluene yield increases as the oxidation temperature increases over the studied catalyst rg-402, rg-412, rg422 and rg-432 respectively and reached a maximum value at 550°c. above 550 the conversion decreases due to the effect of catalyst sintering. no significant change were observed for reduction temperature range 400-600°c for the above studied catalysts. the selectivity order for the studied catalysts and for reduction treatment experiments arranged as follows: rg-422> rg-432> rg-412> rg-402 keywords: platinum catalyst, dehydrogenation, metal dispersion 1. introduction naphtha reforming is usually called “platforming” due to the use of catalysts based on platinum supported on alumina. pt/al2o3 catalysts have been widely used as catalysts. during the naphtha reforming a complex reaction network takes place which includes both desired and undesired reactions. the desired transformations are dehydrogenation of naphthenes, isomerization and dehydrocyclization of paraffins. undesired reactions are the hydrogenolysis and the cracking of paraffins that produce light gases of negligible value and decrease the overall liquid c 5+ yield. coking is another secondary reaction which rate needs to be decreased to prevent the premature deactivation of the catalyst by the accumulation of carbon deposits on the active sites. in bifunctional reforming catalysts used for catalytic reforming of naphtha to produce higher octane number gasoline or aromatics, a careful balance has to be maintained between the hydrogenation–dehydrogenation function of the metal part (pt, and or ir, re, in, etc.) and the acidic function (eg. al2o3 and chlorine). many papers had been published concerning ptre/al2o3 [1,2] and pt-sn/al2o3 [3] catalysts. addition of the iridum component is known to lead to an improvement in the octane number (more branched alkanes, cycloalkanes, and aromatics) and lowers the rate of coke deposition, resulting in an increased stability [4] . the behavior of an ir-pt reforming catalysts was found to be ptcatalyst like under n-heptane reforming experiments. relatively, little has been appeared in literature concerning pt-ir loaded catalysts. in reforming processes, addition of tin to monometallic pt/al2o3 catalysts provides better stability, mitigates the sintering effect, improves selectivity by inhibition of hydrogenolytic effect of platinum, and decrease isomerisation and coke deposition, while aromatization is increased [5-10] . two different effects caused by addition of a second metal are suggested in the literature: one geometrical, in which a physical dilution of ahmed j. ali al-khwarizmi engineering journal, vol. 5, no. 3, pp 77 86 (2009) 78 platinum by a second metal takes place, and one electronic, where the formation of alloys causes a change in bond strength between the chemisorbed hydrocarbon and the active metal [11-15] . acquiring high metal dispersion of active phases on the surface of reaction is the key point in preparing a high active catalyst. researchers, found that the surface area and porosity alone cannot explain the metal dispersion on the catalyst [16] . methylcyclohexane (mch) dehydrogenation has long been used as a model reaction to probe catalytic performance of catalysts [16] . as one of the most effective catalysts for this reaction, pt/al2o3 has been extensively studied [17] . this reaction has gained a renaissance because it is considered an efficient method to store and supply h2 through a reversible hydrogenationdehydrogenation cycle [18] . in the previous work, the study of methylcyclohexane dehydrogenation reforming reactions showed that the former can be used to estimate platinum dispersion in the catalysts, whereas the distribution of products in the latter gives indications on the degree of deactivation of a catalyst and how it will perform in the industrial process [5, 19-22] . in the present study, four types of reforming catalysts with different pt dispersion were used. dehydrogenation of methylcyclohexane in the absence of hydrogen at 450°c was chosen as a model reaction for the comparison of the state of metal function upon oxidation and reduction at different temperatures. 2. experimental work 2.1. methods and materials (i) catalysts four types of catalysts were supplied from ifp (institut français du pétrole) had been used in this work, with platinum varying around the industrial metallic loading (0.35-0.6wt.%). the properties of these cylindrical extrudates catalysts are shown in table 1. the spectroscopy grade methylcyclohexane (fluka) used in this investigation was more than 99% in purity and was passed over a bed of molecular sieve (bdh, type 5a) to remove impurities, notably, water and sulfur containing species. high grade quality hydrogen and nitrogen and oxygen gases with a purity of 99.99% were used in this work. the nitrogen was further purified by passing over a cu bed at 400°c, to remove traces of h2 and o2. then passed over molecular sieve to remove traces of water. traces of o2 and h2o in h2 gas were removed by a matheson deoxe unit and a silica gel column respectively. traces of water in the process gases were removed by a matheson model 450 drier. table 1, catalysts specifications catalyst pt content wt.% promoter (ir) ppm metal dispersion surface area m 2 /g chlorine content wt.% rg-402 0.6 none 64 158 1.02 rg-412 0.35 none 65 162 1.00 rg-422 0.6 500 74 182 1.11 rg-432 0.35 500 80 196 1.09 (ii) catalyst activity test the catalyst activity test experiments were performed in a laboratory fixed bed type reactor with a continuous flow system at atmospheric pressure. the flow diagram of the laboratory reaction unit is shown in fig. 1. the flows of gases were measured by calibrated rotameter and controlled by a needle valve. the flows of gases used were: oxygen-free nitrogen (90 ml/min), nitrogen (114 ml/min) and hydrogen (88 ml/min). nitrogen was used for heating the reactor bed from room temperature to reaction temperature. then the treatment gases were introduced to the reactor according to the conditions of experiments. methylcyclohexane was fed by the calibrated syringe pump at a rate of 6ml/h into the preheater section then to the evaporator section of the reaction zone. methylcyclohexane vapor was then fed to the reactor containing the catalyst bed by ahmed j. ali al-khwarizmi engineering journal, vol. 5, no. 3, pp 77 86 (2009) 79 incoming hydrogen as well as the diluent nitrogen gas. the reactor was a vertical mounted pyrex tube of 2 cm inside diameter and 35 cm long surrounded by a well insulated jacket heater. the temperature was measured by using ni/cr thermocouple and controlled by a temperature controller. reaction period of 30 min were employed in all experiments to ensure the attainment of steady state conditions. a fresh catalyst was used in each experiment. 1.5 g of each catalyst was charged between two layers of inert materials (quartz chips-to serve as a preheating section). the average size of the extruded shape catalyst granules was 1.5 mm in diameter by 4 mm in length. the effluent gases from the reactor were passed through the condenser, which was maintained at about 0°c by ice cubes. the collected liquid products were analyzed by gas-liquid chromatography (intersmat instruments) equipped with stainless steel column of 3.2mm diameter and 2 m long filled with 10% se-30 on chromosorb w and using a flame-ionization detector. methylcyclohexane dehydrogenation reaction yields toluene, benzene, methylcyclohexenes, metylhexadiens and cracked product in the collected liquid phase. it was found that the major products from the dehydrogenation of mch were hydrogen and toluene. 3. results and discussion the conversion of mch to toluene was used as an indication of the extent of dehydrogenation reaction. this reaction was known to be a highly endothermic reaction [8] . inspection of effluent gases from condenser was carried out periodically and only traces amount of benzene were detected. the effect of different oxidizing and or reducing atmosphere on mch dehydrogenation reaction for catalysts listed in table 1 was investigated in this study to see whether this reaction represent the metal dispersion state of the catalysts investigated. 3.1. the effect of oxidizing atmosphere the effect of oxidation treatment on the conversion of mch to toluene at 450°c was fig. 1. catalyst test apparatus. h2 n2 o2 deoxo unit drier heat ed cu bed drier rotameter to vent syringe pump reactor jacket heater thermos filled with ice condenser to vent ahmed j. ali al-khwarizmi engineering journal, vol. 5, no. 3, pp 77 86 (2009) 80 studied over the temperature range 400-600°c and over the four catalysts are shown in fig.2. as shown in fig.2, the catalytic activity increases and toluene yield increases as the temperature increases and reach a maximum value at 550°c. then toluene yield dropped severely at 600°c for both pt and pt-ir catalysts. this behavior was observed for supported pt catalysts, where at temperatures  600°c the catalysts can be sintered in a short time up to a value never obtained in hydrogen atmosphere [21] . various investigators have reported increases in platinum dispersion upon treatment of pt/al2o3 in oxygen containing atmosphere at temperatures 400–580°c, whereas at higher temperatures sintering occurs. most of these studies indicates a maximum dispersion at temperatures 500–580°c [17-22] except the work of hassan et al. [23] who observed a decrease in metal dispersion on increasing oxidation temperature. increases in pt dispersion predicted by most of the investigators was achieved wherever the catalysts containing chlorine or not. lietz et al. [24] had related the increase in metal dispersion to the state of platinum in the catalyst (soluble or crystalline form) as suggested by mchenry et al. [25] for chlorine containing catalysts. the observed relation between metal dispersion and catalytic activity had also been proved by aben et al. [26] for benzene dehydrogenation, dautzenberg and platteeuw [27] for n-hexane dehydrocyclization and isomerization, and lee and kim [28] for cyclohexane hydrogenation. it is clearly appeared from above discussion that the pt–ir catalysts behave like pt catalysts as found by ramaswamy et al. [29] on working with catalysts of low ir content (pt/ir=10:1). the pt–ir catalysts used in this investigation are within this ratio (pt/ir=14:1 to 8:1). granam and wank [19] had approached to a quite different behavior on working with higher ir content catalysts (pt/ir=1:1) after relating metal dispersion to oxidation temperature. 0 10 20 30 40 50 60 70 80 90 100 350 400 450 500 550 600 treatment temperacture, o c t o lu e n e y ie ld , w t% rg-402 rg-412 rg-422 rg-432 fig.2, effect of 1h oxidation treatment on mch dehydrogenation reaction at 450°c. 3.2. the effect of reducing atmosphere as shown in fig.3, the supported pt and pt–ir catalysts are reduced with pure hydrogen at different temperatures followed by mch dehydrogenation reaction at 450°c. a constant mch conversion was observed for both supported 0.6%pt rg-402 and 0.6%pt/ir rg-432 catalysts at different reduction temperatures and as shown in fig.3. this indicates that, reduction at temperatures 400–600°c have somewhat no effect on metal dispersion as indicated by smith et al. [30] and dautzenberg and wolters [17] . reduction of reforming catalysts at different temperatures characterized by hydrogen– chemisorption as an indication of metal dispersion had been the subject of many published works. graham and wank [19] observed a monotonic ahmed j. ali al-khwarizmi engineering journal, vol. 5, no. 3, pp 77 86 (2009) 81 decrease in dispersion upon increasing of reduction temperature for 1% pt and 1%pt–1%ir catalysts. while, dautzenberg and wolters [17] found that crystalline growth does not occur to any extent on reduction at different temperatures for supported 0.4–2%pt catalysts. smith et al. [23] also claimed that, increasing of temperature of reduction (from 500 to 600°c) did not seems to influence the amount of sintering on working with light metal loading, and that particle rounding appeared to be the major change. increasing of pt content from 0.35-0.6 wt.% was appeared to have a slight effect on catalytic activity as shown in fig. 3. 0 10 20 30 40 50 60 70 80 90 100 390 440 490 540 590 treatment temperacture, o c t o lu e n e y ie ld , w t. % rg-402 rg-412 rg-422 rg-432 fig.3, effect of 1h reduction treatment on mch dehydrogenation reaction. 3.3. selectivity and product distribution in this study, only the product distribution over the studied reduction temperature was presented here. product distribution shows that the main reaction is dehydrogenation. concerning dehydrogenation, the selectivity order for the four commercial catalysts is, rg-422> rg-432> rg412> rg-402 and as shown in figs.4 to 8. in this case the evaluation of selectivity with temperature is more interesting; as it was observed that the reaction rate is not controlled by the pt dispersion [17, 20, 22] . liquid product selectivity is shown in figs. 4 to 8, where both catalysts give somewhat similar product distribution. a different behavior was observed for supported 0.35%pt rg-422 and 0.35%pt–ir rg-412 catalysts as shown in fig.6. minimum mch conversions were observed at a reduction temperature of 500°c. hassan et al. [23] had obtained a somewhat similar trend for metal dispersion (indicated by h2chemisorption) upon reduction at different temperatures (300-800°c) for 0.2–2%pt catalysts. the authors had no data observation at a reduction temperature of 500°c, and a minimum dispersion was obtained at 400°c. ahmed j. ali al-khwarizmi engineering journal, vol. 5, no. 3, pp 77 86 (2009) 82 0 10 20 30 40 50 60 70 80 90 100 <c5 n-pentane 2-methyl pentane 3-methyl pentane 2-methyl cyclopentane bz toluene s e le c ti v it y , m o l% rg-422 rg-432 rg-412 rg-402 fig.4, selectivity of products after 1h reduction at 400°c temperature and of mch dehydrogenation reaction at 450°c. 0 10 20 30 40 50 60 70 80 90 100 <c5 n-pentane 2-methyl pentane 3-methyl pentane 2-methyl cyclopentane bz toluene s e le c ti v it y , m o l% rg-422 rg-432 rg-412 rg-402 fig.5, selectivity of products after 1h reduction at 450°c temperature and of mch dehydrogenation reaction at 450°c. ahmed j. ali al-khwarizmi engineering journal, vol. 5, no. 3, pp 77 86 (2009) 83 0 10 20 30 40 50 60 70 80 90 <c5 n-pentane 2-methyl pentane 3-methyl pentane 2-methyl cyclopentane bz toluene s e le c ti v it y , m o l% rg-422 rg-432 rg-412 rg-402 fig.6, selectivity of products after 1h reduction at 500°c temperature and of mch dehydrogenation reaction at 450°c. 0 10 20 30 40 50 60 70 80 90 100 <c5 n-pentane 2-methyl pentane 3-methyl pentane 2-methyl cyclopentane bz toluene s e le c ti v it y , m o l% rg-422 rg-432 rg-412 rg-402 fig.7, selectivity of products after 1h reduction at 550°c temperature and of mch dehydrogenation reaction at 450°c. ahmed j. ali al-khwarizmi engineering journal, vol. 5, no. 3, pp 77 86 (2009) 84 0 10 20 30 40 50 60 70 80 90 100 <c5 n-pentane 2-methyl pentane 3-methyl pentane 2-methyl cyclopentane bz toluene s e le c ti v it y , m o l% rg-422 rg-432 rg-412 rg-402 fig.8, selectivity of products after 1h reduction at 600°c temperature and of mch dehydrogenation reaction at 450°c. 4. conclusions  methylcyclohexane conversion increases as the oxidation temperature increases and reached 71.7, 76.2 79.5 and 82.9 wt.% for rg-402, rg-412, rg-422 and rg-432 catalysts respectively at 550°c. above 550 0 c the conversion decreases due to the effect of catalyst sintering.  increasing pt content from 0.35 to 0.6 wt.% was appeared to have a little effect on catalytic activity for both pt and pt/ir catalysts.  no significant change where observed for reduction temperature range 400-600°c for the above studied catalysts.  the product distribution of the reduction treatment experiment shows that the main reaction is dehydrogenation. the selectivity order for the studied catalysts is as follows: rg-422> rg-432> rg-412> rg-402 from these experimental observations, it appears that, such reforming catalysts as subjected to mch reaction are structure sensitive and this reaction can characterize metal dispersion. 5. references [1] fung, a.s., kelley, m.j., koningsberger and gates, b.c., “γ-al2o3-supported re-pt cluster catalyst prepared from [re2pt(co)12]: characterization by externded x-ray absorption fine structure spectroscopy and catalysis of methylcyclohexane dehydrogenation”, j. am. chem. soc., 119, 5877 (1997). [2] parera, j. m., “deactivation and regeneration of pt-re/al2o3 catalysts”, stud. surf. sci. catal., 68, 103-10 (1991). [3] rajeshwer, d.; basrur, a. g.; gokak, d. t.; krishnamurthy, k. r., “method for metal dispersion measurements in bimetallic ptsn/al2o3 catalysts”, j. catal., 150, 135-42, (1994). [4] duprez, d.; hadj-aissa, m.; barbier, j., “effect of steam on the coking and on the regeneration of metal catalysts: a comparative study of alumina-supported platinum, rhenium, iridium and rhodium catalysts", stud. surf. sci. catal., 68, 111-8 (1991). [5] gonzalez-marcos m.p., guil j.m. inarra b., gutierrez-ortiz, “development of an industrial characterization method for ahmed j. ali al-khwarizmi engineering journal, vol. 5, no. 3, pp 77 86 (2009) 85 naphtha reforming bimetallic pt-sn/al2o3 catalyst through n-heptane reforming test reactions”, catal. today 107-108, 685-692, (2005). [6] anderson, j. r. and avery, n.r., j. catal., 5, 446 (1966). [7] fujikawa t., f.h. ribeiro, g.a. g.a. somorjai, j. catal., 178, 58, (1998). [8] palazov a., ch. bonev, d. shopov, g. lietz, a. sarkang, j. volter, j. catal., 103, 249, (1987). [9] burch, r., l. c. garla, j. catal., 71, 360, (1981). [10] che, m., c.o. bennett, adv. catal., 36, 55, (1986). [11] xiaoyun li., ding ma. and xinhe bao, “dispersion of pt catalysts supported on activated carbon and their catalytic performance in methylcyclohexane dehydrogenation”, j. catal., 29, 3, 259263, (2008). [12] okada y., sasaki e., watanabe e., hodo s., nishijima h. int. j. hydrogen energy, 31, 10, 1348, (2006). [13] gonzalez-marcos, m.p., b. inarra, j. m. guil, m.a. gutierrezortiz, appl. catal., a273, 259, (2004). [14] ritchie, a.w., nixon, a.c., “dehydrogenation of methylcyclohexane over a platinum-alumina catalyst in absence of added hydrogen”, ind. eng. chem. prod. res. dev. 5, 59-64 (1966). [15] parmaliana, a., frusteri, f., mezzapica, a., giordano, n., “the role of chlorine in the regeneration of hydrogen of coked reforming catalysts”, j. catal. 111, 235242 (1988). [16] straguzzi, g.i., aduriz, h.r., gigola, c.e., “redispersion of platinum on alumina support”, j. catal. 66, 171-183 (1980). [17] dautzenberg, f. m., and h.b.m. wolters, “state of dispersion of platinum in alumina supported catalysts”, j. catal. 51, 26 (1978). [18] fiedorow, r.m.j.; chahar, b. s.; and s. e. wanke, “the sintering of supported metal catalysts. 2. comparison of sintering rates of supported pt, ir, and rh catalysts in hydrogen and oxygen”, j. catal. 51, 193– 202 (1978). [19] graham, a.j. and s. e. wank, “the sintering of supported metal catalysts. 3. the thermal stability of bimetallic pt–ir catalysts supported on alumina”, j. catal. 68, 1–8 (1981). [20] lieske, h., lietz, g., spindler, h., volter, j., “reactions of platinum in oxygen-and hydrogen-treated pt/g-al2o3 catalysts. 1temperature programmed reduction, adsorption, and redispersion of platinum”, j. catal. 81, 8-16 (1983). [21] straguzzi, g.i., aduriz, h.r., gigola, c.e., “redispersion of platinum on alumina support”, j. catal. 66, 171-183(1980). [22] lee, t. j., kim, y.g., “dispersion of supported platinum catalysts in oxygen. 1 experimental evidences of redispersion. kjche 2, 55-61 (1985). [23] hassan, s.a., khalil, f.h., el-gamal, f.g., “the effect of different atmospheres on the sintering of pt/al2o3 catalysts”, j. catal. 44, 5-14 (1976). [24] lietz, g., lieske, h., spindler, h., hanke, w., volter, j., “reactions of platinum in oxygen-and hydrogen-treated pt/g-al2o3 catalysts. 2-ultaviolet-visible studies, sintering of platinum, and soluble platinum”, j. catal. 81, 17-25 (1983). [25] mchenry, k.w; r.j. bertolacini; h.m. brennan; wilson, j. l. and h.s. seeling, “the nature of platinum dehydrocyclization catalyst”, in proc. 2 nd int. cong. catal. (paris), 2295-2311(1961). [26] aben, p.c., platteeuw, j.c., stouthamer, b., in proc. 4 th int. cong. catal. (moscow) 1, 395 (1971). [27] dautzenberg, f.m., platteuw, j.c., j. catal. 24, 364(1972). [28] lee, t.j., kim, y.g., “dispersion of supported platinum catalysts in oxygen. 1 experimental evidences of redispersion. kjche 2, 55-61(1985). [29] ramaswamy, a.v., ratnasamy, p., sivasanker, s., leonard, a.j., “structure, and catalytic properties of bimetallic reforming catalysts”, in proc. 6 th int. cong. catal. (london), 855-862 (1977). [30] smith, d.j., white, d., bird, t., fryer, j.r., “the characterization of a model platinum/alumina catalyst by high resolution electron microscopy”, j. catal., 81, 107-118 (1983). 86 -77، صفحت 3، العذد 5مجلت الخىارزمي الهنذسيت المجلذ احمذ جىاد علي (200 9) 86 تشخيص تشتت المعذن لبعض العىامل المساعذة المستخذمت في تهذيب النافثا بتفاعل إزالت الهيذروجيه لمثيل سيكلى هكسان اميل محمذ رحمه *احمذ جىاد علي جايعح تغذاد / كهٍح انُٓذسح انخٕارسيً/ قسى انُٓذسح انكًٍٍائٍح اإلحٍائٍح* الخالصت ذسرخذو انرً rg-402 ،rg-412، rg-422 ٔrg-432 انًحًهح عهى انعٕايم يساعذج pt ٔpt-irذى دراسح اَرشار انًعذٌ اسرخذو ذفاعم إسانح انٍٓذرٔجٍٍ نًثٍم سٍكهٕ ْكساٌ تغٍاب . نرٓذٌة انُافثا تعذ إجزاء عًهٍاخ األكسذج ٔ االخرشال تضغط جٕي اعرٍادي . انٍٓذرٔجٍٍ كرفاعم اخرثار نٓذِ انذراسح جزخ يحأنح رتط ذصزف انعٕايم انًساعذج انًسرخذيح نٓذا انرفاعم نرٕضٍح ذأثٍز ذشرد انًعذٌ جزاء يعايهرّ تعًهٍاخ األكسذج ٔتٓذا ًٌكٍ انقٕل تاٌ ذفاعم ذحٕل . ًٌكٍ انرعثٍز عٍ انرحٕل انكهً تانرغٍز انذي ٌحذز نرشرد انًعذٌ. ٔاالخرشال انًٕضحح فً األدتٍاخ methylcyclohexaneذفاعم حساص ترغٍز تٍُح انعايم انًساعذ ْٕ . ذشداد تشٌادج درجح حزارج األكسذج نهعٕايم انًساعذج انًسرخذيح نرصم انى أعهى يعذالذٓا عُذ درجح حزارج نٕحظ اٌ َسثح إَراج انرهٌٍٕ . ٔتارذفاع درجح انحزارج نٕحظ اٌ َسثح اإلَراج ٌرُاقص إشارج انى ظاْزج ذهثذ انعايم انًساعذ. و550° . و°600-400نى ٌالحظ أي ذغٍز فً َسة إَراج انرهٌٍٕ عُذ اخرشال انعٕايم انًساعذج تذرجاخ حزارٌح ذزأحد يٍ rg-422> rg-432> rg-412> rg-402 :ًٌكٍ انرعثٍز عٍ اَرقائٍح انعٕايم انًساعذج انًسرخذيح تانرزذٍة انرانً ammar a. hassan /al-khwarizmi engineering journal, vol.3, no. 1 pp 99(2007) ٨١ low cost hardware back propagation algorithm ammar a. hassan computer engineering department / college of engineering university of baghdad (received 12 september 2005; accepted 30 october 2006) abstract:the first successful implementation of artificial neural networks (anns) was published a little over a decade ago. it is time to review the progress that has been made in this research area. this paper provides taxonomy for classifying field programmable gate arrays (fpgas) implementation of anns. different implementation techniques and design issues are discussed, such as obtaining a suitable activation function and numerical truncation technique trade-off, the improvement of the learning algorithm to reduce the cost of neuron and in result the total cost and the total speed of the complete ann. finally, the implementation of a complete very fast circuit for the pattern of english digit numbers nn has four layers of 70 nodes (neurons) on single chip using xilinx fpga technique is given. the main goal of this paper is how to achieve the suitable activation function and weights for this network that gives minimum hardware cost when all stages of this ann algorithm is implemented on fpga. 1.introduction artificial neural networks (anns) are a form of artificial intelligence, which have proven useful in different areas of application, such as pattern recognition [1] and function approximation/ prediction [2]. the most popular neural network is the multi-layer perceptron trained using the error back propagation algorithm [3]. however, an important obstacle in using this network in many applications is the slow training and the lack of clear methodology to determine the network topology before training starts. it is then desirable to speedup the training and allow fast experimentation with various topologies. one possible solution is an implementation on a reconfigurable computing platform (e.g field programmable gate arrays) fpga. reconfigurable computing is a means of increasing the processing density (i.e. greater performance per unit of silicon area) above and beyond that provided by general-purpose computing platform [4]. field programmable gate arrays (fpgas) are a medium that can be used for reconfigurable computing, since they allow for custom design of fine-grain logic compared to course-grain logic found in general-purpose computing platforms. fpgas are a form of programmable logic, which offer flexibility in design like software, but with performance speeds closer to application specific integrated circuits (asics). with the ability to be reconfigured an endless amount of al-khwarizmi engineering journal al-khwarizmi engineering journal, vol.3, no.1, pp 81-90 (2007) this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ ammar a. hassan /al-khwarizmi engineering journal, vol.3, no. 1 pp 99(2007) ٨٢ times after it has already been manufactured, fpgas have traditionally been used as a prototyping tool for hardware designers. however, as growing die capacities of fpgas have increased over the years, so has their use in reconfigurable computing applications too [2, 4]. 2.problem formulation the design problem in ann using fpga is a precision vs. area trade-off. one way to help achieve the density advantage of reconfigurable computing over general-purpose computing is to make the most efficient use of the hardware area available. in terms of an optimal precision vs area trade-off, this can be achieved by determining the minimum allowable precision, whose criterion is to minimize hardware area usage without sacrificing quality of performance. because a reduction in precision introduces more error into the system, minimum allowable precision is actually a question of determining the maximum amount of uncertainty (i.e. quantization error due to limited precision) that an application can withstand before performance begins to degrade. hence, determining a minimum allowable precision and suitable numeric representation to use in hardware is often dependent upon the application at hand, and the algorithm used. fortunately, suitable precision for backpropagation-based anns has already been empirically determined in the past. selecting weight precision is one of the important choices when implementing anns on fpgas. weight precision is used to tradeoff the capabilities of the realized anns against the implementation cost. a higher weight precision means fewer quantization errors in the final implementations, while a lower precision leads to simpler designs, greater speed and reductions in area requirements and power consumption. one way of resolving the tradeoff is to determine the “minimum precision”, required to solve a given problem. traditionally, the minimum precision is found through “trial and error” by simulating the solution in software before implementation. holt and baker [5] studied the minimum precision required for a class of benchmark classification problems and found that 16-bit fixed-point is the minimum allowable precision without diminishing an ann’s capability to learn these benchmark problems. 3.ann example 3.1.structure of the circuit following example [6] present how these two parameters effect on hardware resources. remember that in neural network resources capacity differ from network to other according to number of neurons in each layer. the existence of hidden units allows the network to develop complex feature detectors, or internal representations. fig.(1) shows the application of four layers network to the problem of recognizing english digit numbers. the two dimensional grid containing the numeral “7” forms the input layer (it can be arranged this two dimension array as one dimension, so that, number of input neurons is thirteen). this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ ammar a. hassan /al-khwarizmi engineering journal, vol.3, no. 1 pp 99(2007) ٨٣ the first hidden layer is formed from 40 units each unit might be strongly activated by horizontal line in the input, while the second hidden layer molded from 20 hidden units, each unit fully connected with each unit in the first hidden layer. the output layer has ten units that represent the value of the digit number. knowing that, the behavior of these hidden units is automatically learned not preprogrammed, then the computing weight of each layer in the network accuracy by using c++ programming language and implementing this result on fpga as shown in the next section. 3.2.implementation ann components on fpga digital ann architecture proposed in the previous section is an example of a reconfigurable computing application, where all stages of the algorithm reside together on the fpga at once. these components based in idea of implementation on simple (or basic) arithmetic operations (such as addition and multiplication operations). the floating-point precision is the problem of which an engineer must deal with when testing and validating circuits since it limits quantization errors according to number of bits in each node. therefore, truncation technique will be used in design to reduce the floating-point precision value and employ minimum hardware resources available on fpga. adding to this, choosing the optimal activation function suitable for implementation with truncation technique. previously as declared, the ann algorithm components (such as number of hidden layers and number of units in each fig.(1): multilayer network to learn to classify english numbers 0 1 2 3 4 5 6 7 8 9 output 10 nodes hidden2 20 nodes input 25 nodes hidden1 40 nodes !! this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ ammar a. hassan /al-khwarizmi engineering journal, vol.3, no. 1 pp 99(2007) ٨٤ layer) differ from application to another. the english digit numbers nn is the application used in this work to implement ann on fpga, which is composed from four layers. the quantization error after 5,000 iteration using two types of activation functions are given in table (1). by using sigmoid function and without truncation (30-bit floating-point), quntization error is 0.02 (i.e. 98% of the corrected output). while, by the same method, but using bipolar function instead of sigmoid function, quntization error will be given 0.04. 4.arithmetic architecture for fpga based anns to calculate the cost required for english digit number nn in fpga, it should be declared the way of selecting activation function against truncation approach as following: 4.1.sigmoid function without truncation (30-bit) before calculating the cost of fpga based digit nn, it should be known that this function produced floating-point values. then, it required a large number of logic storage as basic logic cells (lcs) called lookuptables (luts). these lcs are formed as ram to store the output value of this function in each unit in the nn algorithm. for 30-bit flotation-point, ram cost implementation in fpga 30-bit input and 30bit output, for each unit in nn algorithm. then, when sigmoid function applied in algorithm design is increased number of lcs, so that, it increased the over all hardware resources of nn algorithm. the average cost of each unit (node) is calculated according to equation (1).   **/ nnunitcost (1) where, n = number of bits in data bus. α = cost for each multiplier in fpga. β = cost for each adder / subtractor in fpga. δ = cost for each lut in fpga for sigmoid function. ifor n=30 bit with sigmoid function α is a (30*30)-bit multiplier and require about (2250) cell. β is a 30-bit adder / subtractor and require about (225) cell. finally δ requires about (125000) cell using cordic approach. so that, the cost of arithmetic components / unit (for 30-bit sigmoid)  200,000 cell. therefore for english digit nn algorithm from previously, there are seventy units then: total cost (for english digit nn) = 200,000 * 70 = 14,000,000 cell. this process can be achieved approximately by 17 of propagation gates delay. activation function quantization error without truncation (30-bit) direct truncation after learning (10-bit) sigmoid bipolar 2% 4% 13-19% 18-26% table (1): quntization error with and without truncation this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ ammar a. hassan /al-khwarizmi engineering journal, vol.3, no. 1 pp 99(2007) ٨٥ iiwhen applying truncation technique through the learning process with sigmoid function on ann, the unit output precision reduces to be 10-bit and using equation (1). total cost / unit  4000 cell. where n = 10-bit, α = 300 cell, β = 75 cell, and δ = 60 cell. total cost (for english digit nn) = 4000 * 70 = 280,000 cell with over all propagation delay reduced to 7 propagation gates delay. from this result, when applying this technique in nn algorithm design it can reduce number of luts on fpga and so reduce the over all hardware resources capacity. 4.2.bipolar function as demonstrated from previous section, it required a large number of cells to implement nn based on sigmoid function. then, bipolar function instead of sigmoid function in a nn algorithm can be used. where, this function does not need storage cells for the output values in luts, because the output from this function is either “-1” or “1”, this technique called multiplierless technique. this approach has α =1 cell and δ=0 cell therefore, the cost for each unit in a nn algorithm based bipolar function calculated using equation (2). */ nnunitcost  (2) n = number of bits in data bus. β = cost for each adder / subtractor in fpga. iwithout truncation technique (i.e. n=30-bit ) β = 215 cell, therefor the cost / unit  6,500 cell. this process exceeds in 17 propagation gates delay. then, to implement the english digit nn, that included 70 active neurons the total cost  455,000 cell. iiwith truncation technique (i.e. n=10-bit ) β = 64 cell, therefor the cost / unit = 650 cell. also, this process exceeds in 7 propagation gates delay. so that, to implement the english digit nn that included 70 neurons the total cost  45,500 cell. then, the total luts cost of nn can be reduced when applying bipolar function with truncation technique on fpgas. 5.proposed backpropagation algorithm [5] an ann using the classic backpropagation algorithm [6] as in fig.(2) has three basic phases named (1, 2 and 3) of execution the proposed backpropagation algorithm has same structure of the classic backpropagation algorithm with three additional steps for the proposed backpropagation algorithm named (1a, 2a and 3a) as following: this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ ammar a. hassan /al-khwarizmi engineering journal, vol.3, no. 1 pp 99(2007) ٨٦ fig. (2): generic structure of an ann. 5.1.initialization the following initial parameters have to be determined by the ann trainer a priori: (i) )()( nw s kj is defined as the synaptic weight that corresponds to the connection from neuron unit j in the (s-1) th layer, to k in the s th layer of the neural network. (ii)  is defined as the learning rate and is a constant scaling factor. (iii) )(s k is defined as the bias of a neuron, which is similar to synaptic weight in that it corresponds to a connection to neuron unit k in the (s-1)th layer of the ann ,but is not connected to any neuron unit j in the(s-1) th layer. (1a) set counter =0 5.2.forward computation during the forward computation, data from neurons of a lower layer (i.e (s-1) th layer), are propagated forward to neurons in the upper layer (i.e. (s) th layer) via a feedforward connection network. the structure of such a neural network is shown in figure 2, where layers are numbered 0 to m, and neurons are numbered 1 to n. the computation performed by each neuron (in the hidden layer) is as follows: θowh (s) k )(sj s-n j (s) kj (s) k    1 )1( 1 (3) where j < k and s=1,….,m )1(s-n = number of neurons in the (s-1)th layer of the ann. )(s kh = weight sum of the k th neuron in the sth layer. )(s kjw = synaptic weight which corresponds to the connection from neuron unit j in the (s-1) th layer to neuron unit k in the s th layer of the neural network )1( s jo output of the jth neuron in the (s-1) th layer. on the other hand, the output computation of neurons in any layer is as follows: ) f ( ho (s) k (s) k  (4) where k =1,…,n and s= 1,…,m o s k )( = neuron output of the kth neuron in the sth layer. ) f ( h (s) k = activation function computed on the weighted sum h (s) k . this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ ammar a. hassan /al-khwarizmi engineering journal, vol.3, no. 1 pp 99(2007) ٨٧ note that some sort of sigmoid function is often used as the nonlinear activation function, such as the following logsig function as in equation (5) or bipoler as in equation (6) as follows: (-x)sigf(x) exp1 1 log   (5)       01 01 or x f for x bipolerf(x) (6) (2a) increment counter for cycle counter = counter +1. 5.3.backward computation in this step, the weights of the networks are updated. criterion for the learning algorithm is to minimize the error between the expected (or teacher) value and the actual output value that was determined in the forward computation. the following steps are performed: istarting with the output layer, and moving back towards the input layer, calculate the local gradients, as follows:             )1( 1 11 11 sn j )(s j s kj (s) kk(s) k ,...,m s ms δw ot ε (7) t k = the target output for kth neuron in the m layer. )1( sn = number of neurons in the (s+1)th layer of the ann. where  )(s k = error term for the kth neurons in the sth layer. the difference between the teaching signal b _ and the neuron output )(s ko )1( s j = local gradient for the j th neuron in the (s+1)th layer. ,....,m s) ( hfεδ (s) k \(s) k (s) k 1 (8) iiusing the local gradients calculated in step 1, calculate the weight (and bias) changes for all the weights as follows: noδw s)(s j (s) k (s) kj ,..., and j,....,ns k ηδ 1 1 11   (9) where w (s) kj δ is the change in synaptic weight (or bias) corresponding to the gradient of error for connection from neuron unit j in the (s+1) th layer, to neuron k in the s th layer. iiionce all weight (and bias) changes have been calculated in step 2, update all the weights (and biases) as follows: (n) (n) δ) (n www s kj s kj s kj 1 (10) where k = 1,….., n neurons in the s th layer and j = 1,………, n neurons in the (s-1) th layer. )1()( nw s kj = update synaptic weight (or bias) to be used in the (n+1) th iteration of the forward computation. )()( nw s kj = change in synaptic weight (or bias) calculated in the n th iteration of the backward computation, where n =the current iteration. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ ammar a. hassan /al-khwarizmi engineering journal, vol.3, no. 1 pp 99(2007) ٨٨ )()( nw s kj = synaptic weight (or bias) to be used in the n th iteration of the forward and backward computations, where n = the current iteration. (3a) truncation for each counter > q makes a truncation as in equation (11) to the values of the weights )()( nw s kj . ) -) * (/ (n) int (w(n)w nn(s) kj (s) kj 122 (11) where q is a small integer value depends on the ann, it defaults between 5to50. n:number of bits in data bus. for truncation in the range of 10-bit this equation becomes as in equation (12). 10231024 ) * / (n) int (w(n)w (s) kj (s) kj  (12) 6.comparative study the simple example is the four-layer network to the problem of recognizing english digit numbers that has 70 nodes. the implementation of this nn using ise 4.1i on xilinx platform [7, 8] shows the effect of the proposed algorithm on the total cost and the final error as in table (2). 7.conclusion generally, any complete circuit of ann has a very high cost because the high resolution of the weight values required is about 30-bit or more. the truncation of this data to low number such as 10-bit will reduce the total cost to 5% from the total cost but increase the error to more than 10 times. in addition to this, the effect of the transfer function type such as sigmoid or bipolar function declared the cost of the classic nn, where sigmoid function is 30 times over the bipolar transfer function but the bipolar has in average twice the error. this work has shown capability choice of different transfer functions for nn algorithm that are suitable to reduce the hardware cost with an optimal choice of precision value, by applying proposed truncation algorithm to reduced precision value from 30-bit to 10-bit with minimum possible error. the matching of the proposed algorithm with bipolar transfer function will reduce the cost to 0.3% from the total cost and increases activation function number of bits algorithm final error % total nn cost / cell max speed of nn / mhz sigmoid 30 classic 2 14,000,000 35 bipolar 30 classic 4 455,000 35 sigmoid 10 classic with truncation 16 280,000 74 bipolar 10 classic with truncation 22 45,500 74 sigmoid 10 proposed 6 455,000 74 bipolar 10 proposed 9 45,500 74 this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ ammar a. hassan /al-khwarizmi engineering journal, vol.3, no. 1 pp 99(2007) ٨٩ the speed to twice the original speed but increase the error from 2% to 10%. while, the direct truncation with classic learning algorithm with bipolar transfer function will give a very high error reaching to 25% while the truncation using the proposed learning algorithm with bipolar transfer function will reduce the error to less than 10% with the same cost and same speed. 8.references [1] m. skrbek, “fast neural network implementation”, neural network world, vol. vol. 9, n. no. 5, pp. 375–391, 1999. [2] j. g. eldredge, “fpga density enhancement of a neural network through run-time reconfiguration”, master’s thesis, department of electrical and computer engineering, brigham young university, may 1994. [3] d.e rumelhart, j.l mcclelland and pdp research group, parallel distrubuted processing: explorations in the microstructure of cognition, volume 1: foundations, mit press, cambridge, massachusetts, 1986. [4] a. dehon, “the density advantage of configurable computing”, ieee computer, vol. 33, n. 5, pp. 41–49, april 2000. [5] holt, j.l., t.e. baker. back propagation simulations using limited precision calculations, in proceedings of international joint conference on neural networks. 1991. pp 121-126 vol. 2. [6] e. k. knight, “artificial intellingence” mcgraw-hill new york, second edition, 1991. [7] xilinx.com, “virtextm2.5v fpgas”, data sheet, www.xilinx.com, may 1999. [8] wolf, d.f., romero, r. a. f., marques, e. using embedded processors in hardware models of artificial neural networks. in proceedings of sbai simpsَio brasileiro de automao inteligente. 2001. pp 78-83. 9.list of symbols ann: artificial neural network. asic: specific integrated circuit. cordic: coordinate rotation digital computer. fpga: field programmable gate array. lc: logic cell. lut: lookuptable. ram: random access memory. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ ammar a. hassan /al-khwarizmi engineering journal, vol.3, no. 1 pp 99(2007) ٩٠ بناء مستوى واطئ الكّلفة لخوارزمیة االنتشار العكسي عمار عادل حسن كــلیة الھــندسـة/ قـسم ھـندسة الحـاسبـات جامـعة بغـداد :الخالصة كانت قلیلة وقبل أكثر ) anns(من أولى التطبیقات الناجحة التي تم نشُرھا للشبكات العصبیة االصطناعیة یمتاز ھذا الملخص . ذي تم في مجال ھذا النوع من البحوثلذلك حان الوقت لمراجعة التقّدم ال. من عقد بتوفیر الفكرة األساسیة حول تطبیق أصناف األنواع المتوفرة للبوابات المرتبة بصیغة صفوف قابلة تقنیات مختلفة التطبیق وأفكار للتصمیم سیتم . لبناء الشبكات العصبیة االصطناعیة (fpgas)للبرمجة العمل على , كذلك. مثًال الحصول على الدالة الفاعلة والمناسبة وتقنیة التقلیم العددیة, مناقشتھا الحقًا الكلیة وتحسین أداء تحسین خوارزمیة التعلم للتقلیل من كلفة بناء الخلیة العصبیة وبالتالي تقلیل الكلفة بناء دائرة متكاملة لھا السرعة العالیة لتمیز أشكال األرقام اإلنكلیزیة من خالل , وأخیرًا. الشبكة العصبیة على رقاقة واحدة ) خلیة عصبیة(عقدة ) ٧٠(شبكة عصبیة اصطناعیة لھا أربعة طبقات من خالل . xilinx fpgaباستخدام تقنیة this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ al-khwarizmi engineering journal al-khwarizmi engineering journal, vol.4 , no.1 , pp 8-16, (2008) effect of polar component(1-propanol) on the relative volatility of the binary system n-hexane benzene dr. khalid farhod chasib al-jiboury chemical engineering department university of technology (received 11 april 2007 ; accepted 4 october 2007))) abstract: vapor-liquid equilibrium data are presented for the binary systems n-hexane 1-propanol, benzene 1-propanol and n-hexane – benzene at 760 mm of mercury pressure. in addition ternary data are presented at selected compositions with respect to the 1-propanol in the 1-propanol, benzene, nhexane system at 760 mmhg. the results indicate the relative volatility of n-hexane relative to benzene increases appreciably with addition of 1-propanol. keywords: vapor-liquid equilibria, relative volatility, polar component. introduction the rapid growth of the petrochemical industry has led to the wide application of extractive distillation as a means of separating closely boiling compounds. one of the problems in the field of extractive distillation is to find a quantitative method of assessing solvents, in terms of the physical properties of the constituents, in order to select the most efficient solvent for a particular process. the aim of the present study was to determine experimentally the effect of polar components on the relative volatility of binary systems. the binary system studied in this work was composed of n-hexane and benzene. these hydrocarbons are difficult to separate because of closeness of boiling points. 1-propanol was used as a solvent. vapor-liquid equilibria of the binary systems n-hexane – benzene, n-hexane 1-propanol, benzene 1-propanol, and of the ternary system n-hexane – benzene1-propanol was determined at 760 mm of mercury absolute, using a modified colburn recirculating still. the change in relative volatility of n-hexane relative to benzene, in the presence of 1-propanol, was calculated. experimental section chemicals n-hexane, 99 mole % (min.) grade, was obtained from phillips petroleum co., the reagent grade benzene was obtained from merck and co., and the baker analyzed reagent grade 1-propanol was obtained from baker chemical co. table 1 compares the literature (marc, 1998) and experimental values of physical properties of these materials. khalid farhod al-khwarizmi engineering journal ,vol.4, no.1 pp 8-16 (2008) ö !! table 1 properties of materials physical property n-hexane benzene 1-propanol experimental literature experimental literature experimental literature refractive index nd 30 1.36996 1.36949 1.49469 1.49460 1.38146 1.38160 density, 30 g/cm-3 0.65043 0.65026 0.86839 0.86829 0.7962 0.7960 boiling point, 760 mmhg, oc 68.8 68.74 80.1 80.1 97.25 97.29 antoine constants, where log p = a – [b / ( c + t )] , p = mmhg, t = oc a 6.87773 6.89745 7.99733 b 1171.53 1206.35 1569.70 c 224.366 220.237 209.5 apparatus a modified colburn recirculating equilibrium still fig 1 was used to obtain the vapor-liquid equilibrium data. the modifications and the general procedure have been reported in (colburn, a.p., 1984). the mixture is introduced into the equilibrium apparatus via the filler tube of the storage vessel, where the liquid mixture in the reservoir is heated to boiling by a housing heating mantle. the circulation caused by vapor bubbles ensures even heating and mixing, where the heating mantle ensures that the number of vapor bubbles remains constant and that the mixture is heated uniformly. the ascending vapor bubbles thoroughly mix the entire volume of liquid, thus preventing a concentration gradient from forming and the boiling liquid from over-heating. when the vapor bubbles (a) pass the funnel-shaped constriction of the cotrell pump they carry a large quantity of non-vaporized liquid (b) to the phase divider (phase separator). here, the vapor-liquid mixture pours over the thermocouple protection tube. the splashguard which becomes wider higher up, prevents liquid splashes from being vaporized, which would complicate establishment of stationary equilibrium. to prevent partial condensation on the glass walls of the phase divider (phase separator) the equilibrium apparatus is equipped with an evacuated glass mantle consisting of two panes. in the phase divider the vapor phase (a) and the liquid phase (b) are separated. the liquid phase (b) drains off laterally to the sampling port at which it can be sampled through the septum of the screw cap without having to open the apparatus. sampling via a glass syringe also prevents contamination of the sample. to condense the vapor residues present in the liquid phase (b), the outlet flows into a small vessel, on which a liebig cooler is mounted. the vapor (a) flows through the phase divider and a lateral outlet to the dimroth cooler where it condenses. the condensate (a) drips down in a curved tube, which also terminates at a sampling port. the liquid (b) and condensate reflux (a), each arms fitted with a siphon, flow into a common tube. this enables remixing of the two phases before they are returned to the reservoir. the tube extends into the reservoir and ends inside it with its opening facing upward. the liquid rising in the middle of the reservoir draws the returned sample out of the tube and heats it. temperature were measured using a copper – constantan thermocouple and a type k leeds & northrup potentiometer. a bausch & lomb precision refractometer was used to measure the refractive index of the vapor and liquid samples using a sodium d line light source. a cottrell boiling point apparatus was used to check the purity of the compounds and to calibrate the equilibrium still thermocouple. the accuracy of the refractometer was tested by the test pieces supplied by bausch & lomb inc. pressure was measured to within ± 0.5 mm of mercury using a calibrated mercury manometer. khalid farhod al-khwarizmi engineering journal ,vol.4, no.1 pp 8-16 (2008) î í !! fig.1. flow diagram for equilibrium apparatus. procedure the procedures for determining vaporliquid equilibrium data for the three binary systems were essentially those described below. for each of the binary hydrocarbon systems, refractive index calibration curves were obtained with samples of 12 to 15 different known concentrations at 30 oc. the compositions of vapor and liquid samples were read from the calibration curves. in the case the ternary system, three mixtures of n-hexane – benzene in the mole ratios of 25 to 75, 50 to 50, and 75 to 25 were used. 1-propanol was added to each of the above mixtures to give equivalent mole fractions of 0.33, 0.50, 0.67, 0.75, and 0.80 in the ternary mixture. these mixtures were subjected to equilibrium distillation in the modified colburn recirculating still and the vapor and liquid samples were obtained. the 1-propanol in these samples was extracted with water. the hydrocarbon layer was dried overnight by adding crystals of drierite, which removed any traces of water remaining in the hydrocarbon mixture. the composition of the added agentfree samples was determined in the refractometer maintained at 30 oc. discussion of results experimental activity coefficients for the components in the binary mixture were calculated by the following equation (prausnitz et.al., 1980). px py ii tii i   (1) the fugacity coefficient i, was calculated using the pr equation of state, which have the form (sytryjeck et.al., 1986): 2 11ln                      cc t t n t t m (2) where m and n are two empirical factors for each pure component, their values given in table 2 (sytryjeck et.al., 1986). table 2. m and n (pr) factors equation of state compound pr – eos m n 1-propanol 1.1505 0.8075 hexane 0.7939 0.4116 benzene 0.6671 0.4723 axkkka o ijijiaijaijaij                1 (3) ))((  jjaaa iiij o  ,  i iji j j axxa (4) 33131 21                           bb xkkkb ji ijibijbijbij (5)  i ii bxb (6)                              bz bz b b axab abzzb b i ij i i j j 414.0 414.2ln2 828.2ln1ln (7) where                                   n n bb n jiiji j k kj kj j j bb kkxxbbxb kjjk 1 1 33131 2 1 2 b bb kkxx n i ibibi j j j jj                              1 33131 2 (8) the vapor -liquid equilibrium data for the three binaries are reported in tables 3 to 5 and shown graphically in figures 2 to 7. our results are compared to literature data (chen, s. et.al., 2003) khalid farhod al-khwarizmi engineering journal ,vol.4, no.1 pp 8-16 (2008) î î !! table 3 vapor-liquid equilibrium data for hexane–benzene system at 760 mmhg. temp. oc experimental calculated xh yh h b h b 77.6 0.073 0.140 1.46 1.00 1.53 1.00 75.1 0.172 0.268 1.28 1.03 1.36 1.02 73.4 0.268 0.376 1.22 1.05 1.25 1.05 72.3 0.372 0.460 1.12 1.11 1.16 1.08 70.9 0.462 0.540 1.09 1.15 1.11 1.12 70.1 0.585 0.644 1.06 1.18 1.06 1.18 69.4 0.692 0.725 1.03 1.26 1.03 1.24 69.1 0.792 0.807 1.01 1.32 1.01 1.29 69.0 0.828 0.838 1.00 1.34 1.01 1.32 68.9 0.883 0.888 1.00 1.35 1.00 1.35 68.8 0.947 0.950 1.00 1.36 1.00 1.39 68.8 0.962 0.964 1.00 1.36 1.00 1.40 table 4 vapor-liquid equilibrium data for hexane–1-propanol system at 760 mmhg. temp. oc experimental calculated xh yh h 1-p h 1-p 89.6 0.024 0.256 6.04 1.03 6.17 1.00 82.3 0.060 0.490 5.46 1.01 5.25 1.01 74.6 0.144 0.662 3.67 1.01 3.74 1.05 71.9 0.236 0.728 2.81 1.02 2.73 1.13 71.2 0.262 0.716 2.53 1.15 2.52 1.16 70.7 0.370 0.760 1.97 1.20 1.90 1.34 68.4 0.476 0.786 1.67 1.39 1.53 1.55 67.7 0.620 0.800 1.33 1.85 1.32 2.01 67.0 0.752 0.836 1.18 2.41 1.09 2.63 66.4 0.784 0.856 1.18 2.49 1.06 2.82 66.2 0.904 0.916 1.10 3.30 1.01 3.71 65.8 0.954 0.952 1.10 3.85 1.00 4.17 67.2 0.975 0.97 1.05 4.32 1.00 4.40 table 5 vapor-liquid equilibrium data for benzene –1-propanol system at 760 mmhg. temp. oc experimental calculated xb yb b 1-p b 1-p 92.8 0.049 0.142 1.99 1.07 2.34 1.00 88.4 0.104 0.296 2.22 1.12 2.21 1.01 84.8 0.180 0.436 2.10 1.14 2.04 1.02 82.1 0.254 0.530 1.97 1.17 1.88 1.04 79.7 0.398 0.622 1.62 1.33 1.61 1.13 77.4 0.504 0.680 1.47 1.46 1.44 1.24 76.5 0.642 0.728 1.27 1.78 1.25 1.49 76.2 0.764 0.774 1.15 2.31 1.12 1.94 76.1 0.792 0.776 1.11 2.59 1.10 2.11 76.3 0.834 0.812 1.10 2.70 1.06 2.39 76.9 0.916 0.864 1.04 3.75 1.02 3.24 78.2 0.956 0.916 1.01 4.16 1.01 3.89 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 mole fraction of hexane 66 68 70 72 74 76 78 80 82 t e m pe r a t u r e , c o t-x-y curves liquid phase experimental data liquid phase literature data vapor phase experimental data vapor phase literature data   fig.2. boiling point composition curve for hexane – benzene at 760 mmhg. 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 mole fraction of hexane 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 a ct iv it y c oe ff ic ie nt ,  calculated experimental fig.3. activity coefficient composition curve for hexane – benzene at 760 mmhg. 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 mole fraction of hexane 60 65 70 75 80 85 90 95 100 t e m pe r a t u r e , c o t-x-y curves liquid phase experimental data liquid phase literature data vapor phase experimental data vapor phase literature data   fig.4. boiling point composition curve for hexane – 1propanol at 760 mmhg. khalid farhod al-khwarizmi engineering journal ,vol.4, no.1 pp 8-16 (2008) î ï !! 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 mole fraction of hexane 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 a ct iv it y c oe ff ic ie nt ,  calculated experimental fig.5. activity coefficient composition curve for hexane – 1propanol at 760 mmhg. 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 mole fraction of benzene 74 76 78 80 82 84 86 88 90 92 94 96 98 t e m pe r a t u r e , co t-x-y curves liquid phase experimental data liquid phase literature data vapor phase experimental data vapor phase literature data   fig.6. boiling point composition curve for benzene – 1propanol at 760 mmhg. 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 mole fraction of benzene 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 a ct iv it y c oe ff ic ie nt ,  calculated experimental fig.7. activity coefficient composition curve for benzene – 1propanol at 760 mmhg. the data were correlated by the nrtl activity coefficient equations (chen, s. et.al., 2003).                      2 1212 1212 2 2121 21 21 2 21 g ln gxx τg xx gτxγ (9)                      2 2121 2121 2 1212 12 12 2 12 g ln gxx τg xx gτxγ (10)  τexp 1212 -αg  (11)  τexp 2121 -αg  (12) the values of the constants in the correlation were evaluated by using the maximum likelihood principle method providing a mathematical and computational guarantee of global optimality in parameter estimation that provides the best fit to measured data. the objective function in nonlinear parameter estimation problems is given below (anderson et.al., 1978; prausnitz et.al., 1980):                                                     m n y i j i j i j i j tpi j ec x ece i c i e i c i yyxxttpp s 1 1 2222 22 22  (13) where the superscripts c and e indicate calculated and experimental values, respectively, the 2 are the estimated variances of the corresponding variables, and the sum is taken over all m experimental data, and n is the number of compounds in the mixtures. the standard deviation assumed were (marc et.al., 1998; lu et.al., 1989): p = 0.5 mmhg t = 0.1 oc x = 0.001 mole fraction y = 0.005 mole fraction a listing of optimized interaction parameters for nrtl activity coefficient model studied is shown in table 6 for all binary systems. khalid farhod al-khwarizmi engineering journal ,vol.4, no.1 pp 8-16 (2008) î ð !! table 6 optimized interaction parameters for binary systems. system    hexane – benzene 466.2 269.3 0.292 hexane – 1-propanol 822.7 174.8 0.412 benzene1-propanol 296.9 212.6 0.405 the values of activity coefficients calculated by nrtl equations are also given in table 3 to 5. a defined deviation between the calculated and experimented activity coefficients was evaluated by the formula (anderson et.al., 1978):   1)-( 2/122 n nkk  (14) k = deviation of experimental activity coefficients values from calculated values. n = number of experimental points  = defined deviation of k from a mean value of k the deviations are as follows: h – b h – 1-p b – 1-p h b h 1-p b 1-p 0.029 0.023 0.101 0.137 0.112 0.188 maximum and minimum values of the activity coefficients were calculated to show the limits of the experimental deviations. the refractometer error for the n-hexane – benzene and benzene 1-propanol system was within 0.001 mole fraction and for the n-hexane 1propanol system, 0.005 mole fraction. pressure errors were within ± 0.5 mm of hg and temperature errors were within ± 0.1 oc.      c.p.x .p.y γ o t -tat100010 500010 11 1 max   (15)      c.p.x .p.y γ o t tat 100010 500010 -11 1 min   (16) the defined deviation between the experimental activity coefficients and the max and min values calculated by equation 14, in the range of x = 0.15 to x = 0.85, are as follows: h – b h – 1-p b – 1-p h b h 1-p b 1-p  m ax  0.022 0.006 0.034 0.048 0.009 0.013  m in  0.006 0.016 0.026 0.053 0.005 0.012 the defined deviation over the full range will be larger because of the influence of the high error in the end values of ’s. it may be seen from table 3 to 5 that the deviation between the calculated (equation 9 to 12) and experimental values of ’s is maximum in the middle range and this deviation depends on the type of equation applied for calculation the ’s. it is not necessary that the defined deviation between calculated and experimental ’s be between  max  and  min  values as they are only deviations due to experimental errors. mcdermott-ellis test method (mcdermott et.al., 1965) was applied to the activity coefficient – composition data of the binaries. according to mcdermott-ellis test method, two experimental points a and b are thermodynamically consistent if the following condition is fulfilled: d < dmax (17) the local deviation d is given by      n i iaibibia xxd 1 lnln  (18) in this method, it is recommended the use of a fixed value of 0.01 for dmax if the accuracy in the measurement of the vapor and the liquid mole fraction is within 0.001. the local maximum deviation, dmax, due to experimental errors, is not constant, and is given by              n i ibibiaia ibiamax y yxyxxxd 1 1111       nn i ibia i iaib p p xxx 11 lnln2               n bi a ibia t ttxx 1 11 (19) khalid farhod al-khwarizmi engineering journal ,vol.4, no.1 pp 8-16 (2008) î ñ !! table 7 results of thermodynamic consistency test. system d dmax 1-propanol – hexane 0.0243 0.026 hexane – benzene 0.0161 0.021 1-propanol – benzene 0.0274 0.029 1-propanol – hexane – benzene 0.0321 0.035 in accordance with the criterion of the test the data were found to be consistent. the experimental data for all the three binaries show that they are non–ideal in nature. (tongberg et.al., 1992), studying the equilibrium of n-hexane – benzene, reported no separation obtainable at concentration above 97 mole % hexane. this is consistent with the observation made in this investigation. the n-hexane – 1-propanol and benzene – 1-propanol systems evidence minimum boiling azeotropes. it is indicated by the interpolation of the data that n-hexane – 1propanol form an azeotrope at 95 mole % hexane at 65.8 oc, and the benzene – 1propanol form an azeotrope at 77.5 mole % benzene at 76 oc the variation of the relative volatility with the concentration of the solvent in the ternary system is reported in table 8 and shown in figure 8. 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 mole fraction of 1-propanol in the mixture 1.2 1.6 2.0 2.4 2.8 r el at iv e v ol at il it y ,  12 1 2 3 fig 8 effect of 1-propanol on relative volatility of binary system n-hexane – benzene at 760 mmhg table 8 variation of relative volatility with solvent concentration for ternary system n-hexane – benzene1-propanol at 760 mmhg pressure binary mixture mole fraction 1-propanol in mixture temperature oc mole fraction 1-propanol free basis )/( bh xh ' xb ' x p-1 xh y h xb y b 0.25 0.75 0.00 0.33 0.50 0.67 0.75 0.80 74.1 27.0 74.3 78.7 82.3 84.8 0.21 0.193 0.172 0.156 0.154 1.36 0.326 0.346 0.332 0.325 0.327 0.300 0.79 0.807 0.828 0.884 0.846 0.864 0.674 0.654 0.668 0.675 0.673 0.709 1.82 2.21 2.39 2.60 2.67 2.72 0.50 0.50 0.00 0.33 0.50 0.67 0.75 0.80 71.2 67.5 70.2 75.2 80.3 83.0 0.428 0.424 0.400 0.396 0.375 0.368 0.528 0.574 0.572 0.593 0.580 0.574 0.572 0.576 0.600 0.606 0.625 0.632 0.472 0.426 0.423 0.407 0.429 0.426 1.50 1.83 2.00 2.23 2.30 2.31 0.75 0.25 0.00 0.33 0.50 0.67 0.75 0.80 69.4 66.3 68.2 72.8 78.2 80.7 0.684 0.681 0.632 0.658 0.635 0.605 0.724 0.776 0.744 0.776 0.766 0.746 0.316 0.324 0.378 0.342 0.365 0.395 0.276 0.224 0.256 0.224 0.234 0.251 1.31 1.63 1.71 1.80 1.88 1.92 x'= solvent free basis khalid farhod al-khwarizmi engineering journal ,vol.4, no.1 pp 8-16 (2008) î ò !! conclusion the data show that the greatest change of relative volatility is obtained at higher concentration of the solvent. as the vapor and liquid samples were extracted with water, it was ensured by laboratory tests that the solvent–free hydrocarbon concentration did not change because of the different solubilities of the hydrocarbons in water. also, it was found that the drying agent, drierite, had no selective absorption capacity for the hydrocarbon mixture involved. nomenclature ai combining rule coefficient aij mixing rule coefficient o ija mixing rule coefficient a cohesion parameter of cubic equation of state bi combining rule coefficient b covolume term (parameter) of the cubic equation of state bi combining rule coefficient ijk a interaction coefficient of equation of state ijkb interaction coefficient of equation of state m temperature dependent correlation parameter n temperature dependent correlation parameter nd refractive index p equilibrium pressure of the system, mpa pi vapor pressure of pure component i mpa t temperature, k tc critical temperature, k xi mole fraction of component i in liquid phase yi mole fraction of component i in vapor phase z compressibility factor greek litters  temperature dependency of the attractive term of equation of state  relative volatility  activity coefficient  standard deviation  density 2 estimated variance  fugacity coefficient references anderson, t. f., d. s. abrams, and e. a. grens. evaluation of parameters for nonlinear thermodynamic models, aiche j., 24, 20. 1978. chen, s,. and yan, c., “vapor-liquid equilibrium calculations of azeotropic mixtures using the peng-robinson equation of state and various activity coefficients models”, j. chem. eng. of japan, 27, 512-516, 2003, internet resources, available at http://www.scej.org/ronbun/jceje/ e27_0512.html. colburn, a.p, ind. eng. chem., 35, 666, 1984 lu, b. c. and m. kato, the use of twoparameter equation of state for predicting vapor-liquid equilibria, int. chem. eng. symp. , 56, 57. 1989 marc, j. a., martin, j. p. and thamas, f. t., “thermophysical properties of fluid, an introduction to their prediction”, imperial college press, first reprint, 1998. mcdermott, c., ellis, s. r. m., “a multicomponent consistency test”, chem. eng. sci., 20, 293, 1965. prausnitz, j. m., c. a. eckert, r. v. orye, and j. p. o’connell. computer calculations for multicomponent vapor-liquid and liquidliquid equilibria, prentice hill, englewood cliffs, new jersey, 1980. sytryjeck, r. and j. h. vera, an improved peng robinson equation of state for pure and mixture, j. of chem. eng., 64, 323, 1989. tongberg, c.o., johnston, f., ind. eng. chem., 25, 734, 1992 khalid farhod al-khwarizmi engineering journal ,vol.4, no.1 pp 8-16 (2008) î ó !! بنزین –نظام الثنائي ھكسان على التطایریة النسبیة لل) بروبانول١(تأثیر المركب القطبي !!!!! ! ! !!!!œ!!! ! !! !!! !! !!!! ! !!! !!!!! ! !! !š! !! !! !!!!!ÿ! !š!!!! : الخالصة ان –تم عرض بیانات إتزان بخار ة ھكس زین -١ –سائل لألنظمة الثنائی انول، بن ان -١ –بروب انول و ھكس ي –بروب زین ف بن غط ق ٧٦٠ض م زئب ى . مل بة إل ارة بالنس ز مخت ي لتراكی ام الثالث ات النظ رض بیان م ع ك ت ى ذل افة إل ام -١باإلض ي نظ انول ف -١بروب د إزدادت . ملم زئبق ٧٦٠بروبانول، بنزین، ھكسان في ضغط زین ق ى البن بة ال ان بالنس بیة للھكس النتائج أشارت الى إنھ التطایریة النس .بروبانول-١عند إضافھ بصورة ملموسة !! n d 30 p x p y i i t i i i f g = 2 1 1 ln ú ú ú û ù ê ê ê ë é + ú ú û ù ê ê ë é = c c t t n t t m a a x k k k a o ij i ji a ij a ij a ij ú ú û ù ê ê ë é ÷ ÷ ø ö ç ç è æ + = 1 ) )( ( a a j j a a a i i ij o = å å = i ij i j j a x x a 3 3 1 3 1 2 1 ÷ ÷ ÷ ø ö ç ç ç è æ + ú ú û ù ê ê ë é ÷ ÷ ø ö ç ç è æ + = b b x k k k b j i i ji b ij b ij b ij å = i i i b x b ( ) ( ) ÷ ÷ ø ö ç ç è æ ú ú ú ú û ù ê ê ê ê ë é = + ¢ ¢ f å b z b z b b a x a b a b z z b b i ij i i j j 414 . 0 414 . 2 ln 2 828 . 2 ln 1 ln å å å = = = ú ú ú û ù ê ê ê ë é ÷ ÷ ÷ ø ö ç ç ç è æ + ÷ ÷ ø ö ç ç è æ ÷ ø ö ç è æ + = ¢ n n b b n ji ij i j k k j k j j j b b k k x x b b x b kj jk 1 1 3 3 1 3 1 2 1 2 b b b k k x x n i i b i b i j j j j j + å = ú ú ú û ù ê ê ê ë é ÷ ÷ ÷ ø ö ç ç ç è æ + ÷ ÷ ø ö ç ç è æ 1 3 3 1 3 1 2 0 . 0 0 . 1 0 . 2 0 . 3 0 . 4 0 . 5 0 . 6 0 . 7 0 . 8 0 . 9 1 . 0 m o l e f r a c t i o n o f h e x a n e 6 6 6 8 7 0 7 2 7 4 7 6 7 8 8 0 8 2 t e m p e r a t u r e , c o t x y c u r v e s l i q u i d p h a s e e x p e r i m e n t a l d a t a l i q u i d p h a s e l i t e r a t u r e d a t a v a p o r p h a s e e x p e r i m e n t a l d a t a v a p o r p h a s e l i t e r a t u r e d a t a l n 0 . 0 0 . 1 0 . 2 0 . 3 0 . 4 0 . 5 0 . 6 0 . 7 0 . 8 0 . 9 1 . 0 m o l e f r a c t i o n o f h e x a n e 0 . 6 0 . 8 1 . 0 1 . 2 1 . 4 1 . 6 1 . 8 2 . 0 2 . 2 a c t i v i t y c o e f f i c i e n t , g c a l c u l a t e d e x p e r i m e n t a l 0 . 0 0 . 1 0 . 2 0 . 3 0 . 4 0 . 5 0 . 6 0 . 7 0 . 8 0 . 9 1 . 0 m o l e f r a c t i o n o f h e x a n e 6 0 6 5 7 0 7 5 8 0 8 5 9 0 9 5 1 0 0 t e m p e r a t u r e , c o t x y c u r v e s l i q u i d p h a s e e x p e r i m e n t a l d a t a l i q u i d p h a s e l i t e r a t u r e d a t a v a p o r p h a s e e x p e r i m e n t a l d a t a v a p o r p h a s e l i t e r a t u r e d a t a l n 0 . 0 0 . 1 0 . 2 0 . 3 0 . 4 0 . 5 0 . 6 0 . 7 0 . 8 0 . 9 1 . 0 m o l e f r a c t i o n o f h e x a n e 1 . 0 2 . 0 3 . 0 4 . 0 5 . 0 6 . 0 7 . 0 8 . 0 a c t i v i t y c o e f f i c i e n t , g c a l c u l a t e d e x p e r i m e n t a l 0 . 0 0 . 1 0 . 2 0 . 3 0 . 4 0 . 5 0 . 6 0 . 7 0 . 8 0 . 9 1 . 0 m o l e f r a c t i o n o f b e n z e n e 7 4 7 6 7 8 8 0 8 2 8 4 8 6 8 8 9 0 9 2 9 4 9 6 9 8 t e m p e r a t u r e , c o t x y c u r v e s l i q u i d p h a s e e x p e r i m e n t a l d a t a l i q u i d p h a s e l i t e r a t u r e d a t a v a p o r p h a s e e x p e r i m e n t a l d a t a v a p o r p h a s e l i t e r a t u r e d a t a l n 0 . 0 0 . 1 0 . 2 0 . 3 0 . 4 0 . 5 0 . 6 0 . 7 0 . 8 0 . 9 1 . 0 m o l e f r a c t i o n o f b e n z e n e 0 . 5 1 . 0 1 . 5 2 . 0 2 . 5 3 . 0 3 . 5 4 . 0 4 . 5 5 . 0 a c t i v i t y c o e f f i c i e n t , g c a l c u l a t e d e x p e r i m e n t a l ( ) ú ú û ù ê ê ë é + + ÷ ÷ ø ö ç ç è æ + = 2 12 1 2 12 12 2 21 2 1 21 21 2 2 1 g ln g x x τ g x x g τ x γ ( ) ú ú û ù ê ê ë é + + ÷ ÷ ø ö ç ç è æ + = 2 21 2 1 21 21 2 12 1 2 12 12 2 1 2 g ln g x x τ g x x g τ x γ ( ) τ exp 12 12 α g = ( ) τ exp 21 21 α g = å å = ï ï ï þ ï ï ï ý ü ï ï ï î ï ï ï í ì = ÷ ÷ ø ö ç ç è æ + ÷ ÷ ø ö ç ç è æ + ÷ ø ö ç è æ + ÷ ø ö ç è æ = m n y i j i j i j i j t p i j e c x e c e i c i e i c i y y x x t t p p s 1 1 2 2 2 2 2 2 2 2 s s s s ( ) 1) ( 2 / 1 2 2 n n k k å å = w ( ) ( ) ( ) ( ) c . p . x . p . y γ o t t at 1 0 001 0 5 0 001 0 1 1 1 max + + = ( ) ( ) ( ) ( ) c . p . x . p . y γ o t t at 1 0 001 0 5 0 001 0 1 1 1 min + + = ( ) ( ) å = + = n i ia ib ib ia x x d 1 ln ln g g ( ) å = ÷ ÷ ÷ ø ö ç ç ç è æ + + + + d = n i ib ib ia ia ib ia max y y x y x x x d 1 1 1 1 1 ( ) å å = + = d + d + n n i ib ia i ia ib p p x x x 1 1 ln ln 2 g g ( ) å = ÷ ÷ ÷ ø ö ç ç ç è æ + + d + n b i a ib ia t t t x x 1 1 1 0 . 0 0 . 1 0 . 2 0 . 3 0 . 4 0 . 5 0 . 6 0 . 7 0 . 8 0 . 9 m o l e f r a c t i o n o f 1 p r o p a n o l i n t h e m i x t u r e 1 . 2 1 . 6 2 . 0 2 . 4 2 . 8 r e l a t i v e v o l a t i l i t y , a 1 2 1 2 3 ) / ( b h a x h ' x b ' x p 1 x h y h x b y b o ij a ij k a ij k b correlation for fitting multicomponent vapor-liquid equilibria data and prediction of azeotropic behavior al-khwarizmi engineering journal al-khwarizmi engineering journal, vol.4 , no.1 , pp 8-16, (2008) effect of polar component(1-propanol) on the relative volatility of the binary system n-hexane benzene dr. khalid farhod chasib al-jiboury chemical engineering department university of technology (received 11 april 2007 ; accepted 4 october 2007) abstract: vapor-liquid equilibrium data are presented for the binary systems n-hexane 1-propanol, benzene 1-propanol and n-hexane – benzene at 760 mm of mercury pressure. in addition ternary data are presented at selected compositions with respect to the 1-propanol in the 1-propanol, benzene, n-hexane system at 760 mmhg. the results indicate the relative volatility of n-hexane relative to benzene increases appreciably with addition of 1-propanol. keywords: vapor-liquid equilibria, relative volatility, polar component. introduction the rapid growth of the petrochemical industry has led to the wide application of extractive distillation as a means of separating closely boiling compounds. one of the problems in the field of extractive distillation is to find a quantitative method of assessing solvents, in terms of the physical properties of the constituents, in order to select the most efficient solvent for a particular process. the aim of the present study was to determine experimentally the effect of polar components on the relative volatility of binary systems. the binary system studied in this work was composed of n-hexane and benzene. these hydrocarbons are difficult to separate because of closeness of boiling points. 1-propanol was used as a solvent. vapor-liquid equilibria of the binary systems n-hexane – benzene, n-hexane 1-propanol, benzene 1-propanol, and of the ternary system n-hexane – benzene1-propanol was determined at 760 mm of mercury absolute, using a modified colburn recirculating still. the change in relative volatility of n-hexane relative to benzene, in the presence of 1-propanol, was calculated. experimental section chemicals n-hexane, 99 mole % (min.) grade, was obtained from phillips petroleum co., the reagent grade benzene was obtained from merck and co., and the baker analyzed reagent grade 1-propanol was obtained from baker chemical co. table 1 compares the literature (marc, 1998) and experimental values of physical properties of these materials. table 1 properties of materials physical property n-hexane benzene 1-propanol experimental literature experimental literature experimental literature refractive index 1.36996 1.36949 1.49469 1.49460 1.38146 1.38160 density, 30 g/cm-3 0.65043 0.65026 0.86839 0.86829 0.7962 0.7960 boiling point, 760 mmhg, oc 68.8 68.74 80.1 80.1 97.25 97.29 antoine constants, where log p = a – [b / ( c + t )] , p = mmhg, t = oc a 6.87773 6.89745 7.99733 b 1171.53 1206.35 1569.70 c 224.366 220.237 209.5 apparatus a modified colburn recirculating equilibrium still fig 1 was used to obtain the vapor-liquid equilibrium data. the modifications and the general procedure have been reported in (colburn, a.p., 1984). the mixture is introduced into the equilibrium apparatus via the filler tube of the storage vessel, where the liquid mixture in the reservoir is heated to boiling by a housing heating mantle. the circulation caused by vapor bubbles ensures even heating and mixing, where the heating mantle ensures that the number of vapor bubbles remains constant and that the mixture is heated uniformly. the ascending vapor bubbles thoroughly mix the entire volume of liquid, thus preventing a concentration gradient from forming and the boiling liquid from over-heating. when the vapor bubbles (a) pass the funnel-shaped constriction of the cotrell pump they carry a large quantity of non-vaporized liquid (b) to the phase divider (phase separator). here, the vapor-liquid mixture pours over the thermocouple protection tube. the splashguard which becomes wider higher up, prevents liquid splashes from being vaporized, which would complicate establishment of stationary equilibrium. to prevent partial condensation on the glass walls of the phase divider (phase separator) the equilibrium apparatus is equipped with an evacuated glass mantle consisting of two panes. in the phase divider the vapor phase (a) and the liquid phase (b) are separated. the liquid phase (b) drains off laterally to the sampling port at which it can be sampled through the septum of the screw cap without having to open the apparatus. sampling via a glass syringe also prevents contamination of the sample. to condense the vapor residues present in the liquid phase (b), the outlet flows into a small vessel, on which a liebig cooler is mounted. the vapor (a) flows through the phase divider and a lateral outlet to the dimroth cooler where it condenses. the condensate (a) drips down in a curved tube, which also terminates at a sampling port. the liquid (b) and condensate reflux (a), each arms fitted with a siphon, flow into a common tube. this enables remixing of the two phases before they are returned to the reservoir. the tube extends into the reservoir and ends inside it with its opening facing upward. the liquid rising in the middle of the reservoir draws the returned sample out of the tube and heats it. temperature were measured using a copper – constantan thermocouple and a type k leeds & northrup potentiometer. a bausch & lomb precision refractometer was used to measure the refractive index of the vapor and liquid samples using a sodium d line light source. a cottrell boiling point apparatus was used to check the purity of the compounds and to calibrate the equilibrium still thermocouple. the accuracy of the refractometer was tested by the test pieces supplied by bausch & lomb inc. pressure was measured to within ± 0.5 mm of mercury using a calibrated mercury manometer. fig.1. flow diagram for equilibrium apparatus. procedure the procedures for determining vapor-liquid equilibrium data for the three binary systems were essentially those described below. for each of the binary hydrocarbon systems, refractive index calibration curves were obtained with samples of 12 to 15 different known concentrations at 30 oc. the compositions of vapor and liquid samples were read from the calibration curves. in the case the ternary system, three mixtures of n-hexane – benzene in the mole ratios of 25 to 75, 50 to 50, and 75 to 25 were used. 1-propanol was added to each of the above mixtures to give equivalent mole fractions of 0.33, 0.50, 0.67, 0.75, and 0.80 in the ternary mixture. these mixtures were subjected to equilibrium distillation in the modified colburn recirculating still and the vapor and liquid samples were obtained. the 1-propanol in these samples was extracted with water. the hydrocarbon layer was dried overnight by adding crystals of drierite, which removed any traces of water remaining in the hydrocarbon mixture. the composition of the added agent-free samples was determined in the refractometer maintained at 30 oc. discussion of results experimental activity coefficients for the components in the binary mixture were calculated by the following equation (prausnitz et.al., 1980). (1) the fugacity coefficient i, was calculated using the pr equation of state, which have the form (sytryjeck et.al., 1986): (2) where m and n are two empirical factors for each pure component, their values given in table 2 (sytryjeck et.al., 1986). table 2. m and n (pr) factors equation of state compound pr – eos m n 1-propanol 1.1505 0.8075 hexane 0.7939 0.4116 benzene 0.6671 0.4723 (3) , (4) (5) (6) (7) where (8) the vapor -liquid equilibrium data for the three binaries are reported in tables 3 to 5 and shown graphically in figures 2 to 7. our results are compared to literature data (chen, s. et.al., 2003) table 3 vapor-liquid equilibrium data for hexane–benzene system at 760 mmhg. temp. oc experimental calculated xh yh h b h b 77.6 0.073 0.140 1.46 1.00 1.53 1.00 75.1 0.172 0.268 1.28 1.03 1.36 1.02 73.4 0.268 0.376 1.22 1.05 1.25 1.05 72.3 0.372 0.460 1.12 1.11 1.16 1.08 70.9 0.462 0.540 1.09 1.15 1.11 1.12 70.1 0.585 0.644 1.06 1.18 1.06 1.18 69.4 0.692 0.725 1.03 1.26 1.03 1.24 69.1 0.792 0.807 1.01 1.32 1.01 1.29 69.0 0.828 0.838 1.00 1.34 1.01 1.32 68.9 0.883 0.888 1.00 1.35 1.00 1.35 68.8 0.947 0.950 1.00 1.36 1.00 1.39 68.8 0.962 0.964 1.00 1.36 1.00 1.40 table 4 vapor-liquid equilibrium data for hexane–1-propanol system at 760 mmhg. temp. oc experimental calculated xh yh h 1-p h 1-p 89.6 0.024 0.256 6.04 1.03 6.17 1.00 82.3 0.060 0.490 5.46 1.01 5.25 1.01 74.6 0.144 0.662 3.67 1.01 3.74 1.05 71.9 0.236 0.728 2.81 1.02 2.73 1.13 71.2 0.262 0.716 2.53 1.15 2.52 1.16 70.7 0.370 0.760 1.97 1.20 1.90 1.34 68.4 0.476 0.786 1.67 1.39 1.53 1.55 67.7 0.620 0.800 1.33 1.85 1.32 2.01 67.0 0.752 0.836 1.18 2.41 1.09 2.63 66.4 0.784 0.856 1.18 2.49 1.06 2.82 66.2 0.904 0.916 1.10 3.30 1.01 3.71 65.8 0.954 0.952 1.10 3.85 1.00 4.17 67.2 0.975 0.97 1.05 4.32 1.00 4.40 table 5 vapor-liquid equilibrium data for benzene –1-propanol system at 760 mmhg. temp. oc experimental calculated xb yb b 1-p b 1-p 92.8 0.049 0.142 1.99 1.07 2.34 1.00 88.4 0.104 0.296 2.22 1.12 2.21 1.01 84.8 0.180 0.436 2.10 1.14 2.04 1.02 82.1 0.254 0.530 1.97 1.17 1.88 1.04 79.7 0.398 0.622 1.62 1.33 1.61 1.13 77.4 0.504 0.680 1.47 1.46 1.44 1.24 76.5 0.642 0.728 1.27 1.78 1.25 1.49 76.2 0.764 0.774 1.15 2.31 1.12 1.94 76.1 0.792 0.776 1.11 2.59 1.10 2.11 76.3 0.834 0.812 1.10 2.70 1.06 2.39 76.9 0.916 0.864 1.04 3.75 1.02 3.24 78.2 0.956 0.916 1.01 4.16 1.01 3.89 fig.2. boiling point composition curve for hexane – benzene at 760 mmhg. fig.3. activity coefficient composition curve for hexane – benzene at 760 mmhg. fig.4. boiling point composition curve for hexane – 1propanol at 760 mmhg. fig.5. activity coefficient composition curve for hexane – 1propanol at 760 mmhg. fig.6. boiling point composition curve for benzene – 1propanol at 760 mmhg. fig.7. activity coefficient composition curve for benzene – 1propanol at 760 mmhg. the data were correlated by the nrtl activity coefficient equations (chen, s. et.al., 2003). (9) (10) (11) (12) the values of the constants in the correlation were evaluated by using the maximum likelihood principle method providing a mathematical and computational guarantee of global optimality in parameter estimation that provides the best fit to measured data. the objective function in nonlinear parameter estimation problems is given below (anderson et.al., 1978; prausnitz et.al., 1980): (13) where the superscripts c and e indicate calculated and experimental values, respectively, the 2 are the estimated variances of the corresponding variables, and the sum is taken over all m experimental data, and n is the number of compounds in the mixtures. the standard deviation assumed were (marc et.al., 1998; lu et.al., 1989): p = 0.5 mmhg t = 0.1 oc x = 0.001 mole fraction y = 0.005 mole fraction a listing of optimized interaction parameters for nrtl activity coefficient model studied is shown in table 6 for all binary systems. table 6 optimized interaction parameters for binary systems. system    hexane – benzene 466.2 269.3 0.292 hexane – 1-propanol 822.7 174.8 0.412 benzene1-propanol 296.9 212.6 0.405 the values of activity coefficients calculated by nrtl equations are also given in table 3 to 5. a defined deviation between the calculated and experimented activity coefficients was evaluated by the formula (anderson et.al., 1978): (14) k = deviation of experimental activity coefficients values from calculated values. n = number of experimental points  = defined deviation of k from a mean value of k the deviations are as follows: h – b h – 1-p b – 1-p h b h 1-p b 1-p 0.029 0.023 0.101 0.137 0.112 0.188 maximum and minimum values of the activity coefficients were calculated to show the limits of the experimental deviations. the refractometer error for the n-hexane – benzene and benzene 1-propanol system was within 0.001 mole fraction and for the n-hexane 1-propanol system, 0.005 mole fraction. pressure errors were within ± 0.5 mm of hg and temperature errors were within ± 0.1 oc. (15) (16) the defined deviation between the experimental activity coefficients and the max and min values calculated by equation 14, in the range of x = 0.15 to x = 0.85, are as follows: h – b h – 1-p b – 1-p h b h 1-p b 1-p  max  0.022 0.006 0.034 0.048 0.009 0.013  min  0.006 0.016 0.026 0.053 0.005 0.012 the defined deviation over the full range will be larger because of the influence of the high error in the end values of ’s. it may be seen from table 3 to 5 that the deviation between the calculated (equation 9 to 12) and experimental values of ’s is maximum in the middle range and this deviation depends on the type of equation applied for calculation the ’s. it is not necessary that the defined deviation between calculated and experimental ’s be between  max  and  min  values as they are only deviations due to experimental errors. mcdermott-ellis test method (mcdermott et.al., 1965) was applied to the activity coefficient – composition data of the binaries. according to mcdermott-ellis test method, two experimental points a and b are thermodynamically consistent if the following condition is fulfilled: d < dmax (17) the local deviation d is given by (18) in this method, it is recommended the use of a fixed value of 0.01 for dmax if the accuracy in the measurement of the vapor and the liquid mole fraction is within 0.001. the local maximum deviation, dmax, due to experimental errors, is not constant, and is given by (19) table 7 results of thermodynamic consistency test. system d dmax 1-propanol – hexane 0.0243 0.026 hexane – benzene 0.0161 0.021 1-propanol – benzene 0.0274 0.029 1-propanol – hexane – benzene 0.0321 0.035 in accordance with the criterion of the test the data were found to be consistent. the experimental data for all the three binaries show that they are non–ideal in nature. (tongberg et.al., 1992), studying the equilibrium of n-hexane – benzene, reported no separation obtainable at concentration above 97 mole % hexane. this is consistent with the observation made in this investigation. the n-hexane – 1-propanol and benzene – 1-propanol systems evidence minimum boiling azeotropes. it is indicated by the interpolation of the data that n-hexane – 1-propanol form an azeotrope at 95 mole % hexane at 65.8 oc, and the benzene – 1-propanol form an azeotrope at 77.5 mole % benzene at 76 oc the variation of the relative volatility with the concentration of the solvent in the ternary system is reported in table 8 and shown in figure 8. fig 8 effect of 1-propanol on relative volatility of binary system n-hexane – benzene at 760 mmhg table 8 variation of relative volatility with solvent concentration for ternary system n-hexane – benzene1-propanol at 760 mmhg pressure binary mixture mole fraction 1-propanol in mixture temperature oc mole fraction 1-propanol free basis 0.25 0.75 0.00 0.33 0.50 0.67 0.75 0.80 74.1 27.0 74.3 78.7 82.3 84.8 0.21 0.193 0.172 0.156 0.154 1.36 0.326 0.346 0.332 0.325 0.327 0.300 0.79 0.807 0.828 0.884 0.846 0.864 0.674 0.654 0.668 0.675 0.673 0.709 1.82 2.21 2.39 2.60 2.67 2.72 0.50 0.50 0.00 0.33 0.50 0.67 0.75 0.80 71.2 67.5 70.2 75.2 80.3 83.0 0.428 0.424 0.400 0.396 0.375 0.368 0.528 0.574 0.572 0.593 0.580 0.574 0.572 0.576 0.600 0.606 0.625 0.632 0.472 0.426 0.423 0.407 0.429 0.426 1.50 1.83 2.00 2.23 2.30 2.31 0.75 0.25 0.00 0.33 0.50 0.67 0.75 0.80 69.4 66.3 68.2 72.8 78.2 80.7 0.684 0.681 0.632 0.658 0.635 0.605 0.724 0.776 0.744 0.776 0.766 0.746 0.316 0.324 0.378 0.342 0.365 0.395 0.276 0.224 0.256 0.224 0.234 0.251 1.31 1.63 1.71 1.80 1.88 1.92 x'= solvent free basis conclusion the data show that the greatest change of relative volatility is obtained at higher concentration of the solvent. as the vapor and liquid samples were extracted with water, it was ensured by laboratory tests that the solvent–free hydrocarbon concentration did not change because of the different solubilities of the hydrocarbons in water. also, it was found that the drying agent, drierite, had no selective absorption capacity for the hydrocarbon mixture involved. nomenclature ai combining rule coefficient aij mixing rule coefficient mixing rule coefficient a cohesion parameter of cubic equation of state bi combining rule coefficient b covolume term (parameter) of the cubic equation of state bi combining rule coefficient interaction coefficient of equation of state interaction coefficient of equation of state m temperature dependent correlation parameter n temperature dependent correlation parameter nd refractive index p equilibrium pressure of the system, mpa pi vapor pressure of pure component i mpa t temperature, k tc critical temperature, k xi mole fraction of component i in liquid phase yi mole fraction of component i in vapor phase z compressibility factor greek litters  temperature dependency of the attractive term of equation of state  relative volatility  activity coefficient  standard deviation  density 2 estimated variance  fugacity coefficient references anderson, t. f., d. s. abrams, and e. a. grens. evaluation of parameters for nonlinear thermodynamic models, aiche j., 24, 20. 1978. chen, s,. and yan, c., “vapor-liquid equilibrium calculations of azeotropic mixtures using the peng-robinson equation of state and various activity coefficients models”, j. chem. eng. of japan, 27, 512-516, 2003, internet resources, available at http://www.scej.org/ronbun/jceje/ e27_0512.html. colburn, a.p, ind. eng. chem., 35, 666, 1984 lu, b. c. and m. kato, the use of two-parameter equation of state for predicting vapor-liquid equilibria, int. chem. eng. symp. , 56, 57. 1989 marc, j. a., martin, j. p. and thamas, f. t., “thermophysical properties of fluid, an introduction to their prediction”, imperial college press, first reprint, 1998. mcdermott, c., ellis, s. r. m., “a multicomponent consistency test”, chem. eng. sci., 20, 293, 1965. prausnitz, j. m., c. a. eckert, r. v. orye, and j. p. o’connell. computer calculations for multicomponent vapor-liquid and liquid-liquid equilibria, prentice hill, englewood cliffs, new jersey, 1980. sytryjeck, r. and j. h. vera, an improved peng robinson equation of state for pure and mixture, j. of chem. eng., 64, 323, 1989. tongberg, c.o., johnston, f., ind. eng. chem., 25, 734, 1992 تأثير المركب القطبي (1-بروبانول) على التطايرية النسبية للنظام الثنائي هكسان – بنزين د. خالد فرهود قسم الهندسة الكيمياوية الجامعة التكنولوجية الخلاصة : تم عرض بيانات إتزان بخار – سائل للأنظمة الثنائية هكسان – 1-بروبانول، بنزين – 1-بروبانول و هكسان – بنزين في ضغط 760 ملم زئبق. بالإضافة إلى ذلك تم عرض بيانات النظام الثلاثي لتراكيز مختارة بالنسبة إلى 1-بروبانول في نظام 1-بروبانول، بنزين، هكسان في ضغط 760 ملم زئبق. النتائج أشارت الى إنه التطايرية النسبية للهكسان بالنسبة الى البنزين قد إزدادت بصورة ملموسة عند إضافه 1-بروبانول. � embed pbrush ��� 1 page 9 _1237405551.unknown _1237452542.unknown _1237469451.unknown _1237469660.unknown _1263752029.unknown _1237469538.unknown _1237469559.unknown _1237469579.unknown _1237469521.unknown _1237469324.unknown _1237469349.unknown _1237453004.unknown _1237406053.unknown _1237408494.unknown _1237405994.unknown _1058895914.unknown _1060789742.unknown _1237370783.unknown _1237404980.unknown _1060789743.unknown _1173207870 _1060688046.unknown _1060789639.unknown _1060688094.unknown _1060680737.unknown _1058446222.unknown _1058469767.unknown _1058470572.unknown _1058470696.unknown _1058465160.unknown _1055534564.unknown _1056362361.unknown _1055533940.unknown _1055534325.unknown _1055525244.unknown 57 al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 4, no. 3, pp 5765 (2008) a new fractal printed dipole antenna based on tent transformations for wireless communication applications jawad k. ali department of electrical and electronic engineering, university of technology, p.o. box 35239, baghdad, iraq emal: jawengin@yahoo.com (received 10 march 2008; accepted 15 june 2008) abstract in this paper, a compact multiband printed dipole antenna is presented as a candidate for use in wireless communication applications. the proposed fractal antenna design is based on the second level tent transformation. the space-filling property of this fractal geometry permits producing longer lengths in a more compact size. theoretical performance of this antenna has been calculated using the commercially available software ie3d from zeland software inc. this electromagnetic simulator is based on the method of moments (mom). the proposed dipole antenna has been found to possess a considerable size reduction compared with the conventional printed or wire dipole antenna designed at the same design frequency and using the same substrate specifications. results have shown that the proposed design possesses a multi-band resonant behavior with adequate radiation performance with vswr ≤ 2 (return loss ≤-10 db) throughout the resonating bands. this makes the presented antenna (or its monopole counterpart) suitable for use in the modern multi-functions compact communication systems. keywords: fractal antenna, antenna miniaturization, multi-band antenna, printed dipole antenna, ifs (iteration function system). 1. introduction the word fractal comes from latin fractus, which means broken lines, and mandelbrot [1] first used it. mandelbrot defined fractal as a rough or fragmented geometric shape that can be subdivided in parts, each of which is (at least approximately) a reduced-size copy of the whole. euclidean geometries are limited to points, lines, sheets, and volumes and assigns an integer number to describe the dimension of each of these geometries; where the dimension of a point is zero, and 1, 2, and 3 are the dimensions of the line, sheet and volume respectively. fractal geometry describes objects in nature by dimensions, which are not conditionally integer numbers as the euclidean geometry implies. euclidean geometries can be special cases from the more general fractal geometries. fractals can be either random or deterministic. most fractal objects found in nature are random, that have been produced randomly from a set of non-determined steps. fractals that have been produced as a result of an iterative algorithm, generated by successive dilations and translations of an initial set, are deterministic. fractals are characterized by the selfsimilarity, the fractional dimension and spacefilling properties. the concept of a fractal is most often related with geometrical objects satisfying the criteria of self-similarity. self-similarity means that an object is composed of sub-units and sub-sub-units on multiple levels that statistically resemble the structure of the whole object. these substructures are exactly of the shape as the original but it may be flipped, rotated, or stretched depending on the generation process producing the fractal shape. figs (1) and (2) demonstrate this property through the generation process of wellknown fractal geometries; peano and hilbert fractals. mailto:jawengin@yahoo.com jawad k. ali al-khwarizmi engineering journal, vol. 4, no. 3, pp 57-65 (2008) 58 fig.1. the first four iteration levels to generate the peano pre-fractal curve. fig.2. the first four iteration levels to generate the hilbert pre-fractal curve. the second concept for a fractal is a fractional dimension. this requirement distinguishes fractals from the euclidean geometries, which have integer dimensions. the common intuitive idea of dimension is referred to as topological dimension. a point, a line segment, a square and a cube have topological dimensions zero, one, two and three, respectively. this intuitive dimension is always expressed as an integer. in [1, 2] the hausdroff-besicovich dimension is referred to as the fractional dimension, and it is defined as, a real number that precisely measures the object’s complexity. mandelbrot defines a fractal as a set for which the hausdroffbesicovich dimension strictly exceeds the topological dimension. he refers to this dimension as the fractal dimension of a set. fractional dimension is related to self-similarity in that; the easiest way to create a figure that has fractional dimension is through self-similarity. the character of non-integer dimension causes the fractal dimension to be useful in measurement, analysis and classification of many fractal shapes, for example, the fractal dimension provides a way to measure how rough fractal curves are. in addition, the fractal dimension can describe how much a fractal curve fills the space. fractal structures have found increasing applications in different aspects of science and arts. they are successfully used in the fields of physics, chemistry, biology, architecture, etc… [3]. the research in the field of electrodynamics began soon after the scientists discovered the practical aspects of the fractal geometry. most efforts had been devoted to understand the physical process and mathematical background of the interaction between electromagnetic waves and fractal structures [4-6] in passive microwave circuits design, such in the design of the different types of filters, fractals have been used widely and extraordinary results were obtained. the space-filling property of fractals had led to producing miniaturized sizes of passive microwave circuits for compact wireless communication systems. in microwave antenna design, size miniaturization of the normal printed dipole antenna can be accomplished either by the use of high dielectric constant substrates instead of air or some foam materials with dielectric constant nearly like that of air, by the modification of the basic dipole shape, or by a combination of these two techniques [7]. employing high dielectric constant substrates is the simplest solution, but it exhibits narrow bandwidth, high loss and poor efficiency due to surface wave excitation [7]. fractals are supposed to be considered in the second category, i.e., antenna shape modification. in this sense, the space-filling property of the fractal antenna offers the required compact size, while its self-similarity makes it resonates in more than one frequency band, due to the many resonating substructures it consists of in the whole structure [8]. the use of fractals in microwave antenna design has dramatically increased in the recent years, where miniaturized and multiband antennas have to meet the challenges imposed upon the jawad k. ali al-khwarizmi engineering journal, vol. 4, no. 3, pp 57-65 (2008) 59 modern communication systems to be compact and multi-functional. in this paper a fractal printed dipole antenna based on the second level (n =2) tent transformation has been presented as a candidate for use in modern compact and multi-function communication systems. the proposed antenna dimensions can be optimized to satisfy the compact size and the required radiation characteristics for the specified applications operation. 2. fractal dipole antennas since the application of the fractal concept on electrodynamics, much work has been devoted to antenna design [9-17]. the first reported small fractal antenna is the koch dipole [9]. in this work, some of the classical features such bandwidth, resonance frequency, and radiation resistance had been improved. later, different fractal geometries, such as hilbert, peano, minkowski, sierpinski etc..., have been applied to dipole antenna design [10-17]. the reported designs offered astonishing results of antenna performance, whether in the compact size gained or in the multi-resonant behavior they possess. in figs (1) and (2), hilbert and peano fractal curves up to the fourth iteration level, )4( n are depicted, for the sake of comparison with the presented tent curve fractal. these fractals have been widely used in dipole antenna design. an interesting point of comparison in this context is the total length of the fractal in each iteration level as a function of the side length, l, of the area containing it. this factor acquires its importance from the fact that it mainly determines the lowest resonance frequency of the multi-band fractal dipole, and hence the reduction in size gained in comparison with the classical dipole antenna or other fractally designed dipoles. for the hilbert fractal curve, the total length, sn, in the n th order generation level is given in [18] by: ls n n )12(  …(1) where, l is the side length. while for the peano fractal curve, the total length, sn is given by [13] as: ls n n )13(  …(2) where, sn, n, and l are as defined earlier. it is obvious from equs. (1), and (2) that, the total length of the curve offered by peano fractal is greater than that offered by hilbert fractal of the same generation order with the same side length. this means that peano fractal curve presents better antenna miniaturization than hilbert fractal does, when it is used in the design of a fractal dipole. 3. fractal tent transformation the generation process of the fractal curve based on tent transformations is more complicated than those of the hilbert and peano fractals. the presented fractal curve is constructed by applying geometrical transformations of a unit square with a side length l, representing the wellknown tent function, fig.(3a) using the transformation algorithm, which is called multiple reduction copy machine (mrcm) as proposed by [19]. this mrcm provides a good metaphor for what is known as deterministic iterated function systems (ifs) in mathematics. the mrcm generates a dynamical iterated function system (ifs), fig. (3b), [19]. using such an ifs, it is possible to produce a generation level in which all line segments join up to form a single path. as it is clear from fig (3b), the ifs constructs such a curve with five transformations, and the spacefilling property follows from the invariance of the initial square, the tent function, under the ifs. these five transformations, labeled as a, b, c, d, and e, which produce any fractal level from its preceding one, are summarized in table1. in each transformation, more than one operation has to be performed on the original tent function, such stretching, flipping, and/or rotation. figs (4a-d) show the generated tent fractal curve up to the fourth order (n = 4). table 1 summary of steps to generate a fractal tent transformation. step width stretched by height stretched by flipping rotation (deg.) a 2/3 1/3 horizontal none b 1/3 2/3 horizontal none c 1/3 2/3 horizontal 90 d 2/3 1/3 none -90 e 2/3 2/3 none -90 jawad k. ali al-khwarizmi engineering journal, vol. 4, no. 3, pp 57-65 (2008) 60 (a) (b) fig.3. (a); the starting tent function as the initiator structure, and (b); the iteration function system used to generate the tent fractal curve at the different iteration levels [19]. as shown in figs (4a-d), the constructed curve in a certain generation level (n) is simply a collage of the five transformations of the previous level )1( n . because the initial tent function has a suitable symmetry, one can easily be misled when applying the ifs. the ifs uses the unit square with the inscribed letter l as an indication of the orientation as the initial square, fig (3a). a b c d fig.4. the details of the generation steps of the tent fractal curve. structures from (a) to (d) correspond to the first four generation levels. jawad k. ali al-khwarizmi engineering journal, vol. 4, no. 3, pp 57-65 (2008) 61 it has been found that the total length sn, of the tent fractal curve at the n th generation, is: las n n n 1) 3 7 (  …(3) where an is a constant depending on the starting angle θ, of the initial tent function. however, the value of this angle is bounded by an upper limit of θ = 63.435 º ; at which all the vertices of the triangle touches the square, as shown in fig (5), and a lower limit of θ = 0 º , at which the tent function is considered as a straight line of length equals to the side length, l of the square containing it. from fig (5), the tent function is given as: ...(4) and the angle θ is defined as: a1tan thus:  435.630  for which: la 0 it has also been found that an, in equ (3), is varied as: 236.21  na for:  435.630  it is worth to note that for θ = 63.435 º , the tent curve has no longer be a fractal after the 3 rd generation step, since at the 4 th generation step the resulting curve is not self-avoiding . fig (6) shows an enlarged copy of fig (4d). the two circles indicate that the same two points in the space have been visited twice. nevertheless, the fractal curve can be used at this value of θ, up to the 3 rd generation, since a maximum space-filling is gained according to eqn. (3), and it is still selfavoiding. practically, if fractal curves are applied, few numbers of iterations are enough to model an antenna [8,11,14]. however, to generate a tent fractal self-avoiding curve with higher generation levels, the starting angle must be reduced. a comparison of equs(1), (2), and (3) shows that the presented fractal curve has the best spacefilling property than both hilbert and peano fractal curves at the same generation order and the same side length l. for example, at n = 2, the total fractal curve length sn, is given as: , for hilbert fractal curve , for peano fractal curve for tent fractal curve this means that, the tent fractal curve will offer the best dipole antenna miniaturization as compared with the other two. 4. antenna design and performance evaluation up to the author’s knowledge, the only published work about the use of tent fractal dipole antenna in the uhf band is that of hödlmayr [20]. in that work, a wire dipole antenna has been designed and operated at this band. the concentration there is focused from practical point of view. in the present work, a 2 nd iteration tent fractal structure has been modeled as a dipole antenna with two of such a structure composing its two arms as shown in fig.7. the dipole is supposed to be printed on a material with a relative dielectric constant of nearly one, or just built in free space. this will directly permit frequency scaling of the modeled dipole to make it resonating at any desired frequency, since no need of material scaling is required. on the other hand, using a substrate with a dielectric constant greater than one, for the antenna to be printed on, results in reduced antenna efficiency due to the associated losses. in such an antenna with a wide multiband behavior, material scaling becomes an impossible task over this wide frequency range. the antenna is fed with a coaxial cable of 50ω characteristic impedance. the width of the dipole trace has been chosen to be 0.5% the dipole length [12, 21]. the spacing between the two arms constituting the dipole is found to be of less than 5% the dipole length. theoretical calculations of the antenna performance of the antenna and electromagnetic simulation are carried out using ie3d package, from zeland software inc. this em simulator performs performance calculations of 3d electromagnetic structures using the method of moments, (mom). at first, a dipole has been modeled with a side length of 15 mm. the return loss response of this model shows an obvious multiband behavior with first resonance frequency at 7 ghz. this initial structure is then frequency scaled to the desired frequency, 2.45 ghz. the resulting dipole antenna has been found to have a side length of 43.75 mm. the corresponding return loss response of this antenna is depicted in fig.8. the first resonance takes place at a frequency of approximately 2.45 ghz, while other six resonances occur at nearly regular intervals in the jawad k. ali al-khwarizmi engineering journal, vol. 4, no. 3, pp 57-65 (2008) 62 swept frequency range shown in the figure. for demonstration purposes, some of the computed antenna parameters such as the radiation efficiency, the antenna efficiency, the gain (g), and the directivity (d), for many frequency points around the first resonance frequency are listed in table 2. table 2 some antenna parameters around the first resonant frequency. antenna parameters rad. eff. (%) ant. eff. ( %) g ( dbi) d ( dbi) frequency (ghz) 2.100 95.18 76.32 1.151 2.325 2.214 96.21 90.69 1.379 1.804 2.328 95.59 93.57 1.659 1.948 2.442 95.82 95.32 2.142 2.350 2.557 97.81 95.76 2.474 2.662 2.671 98.59 94.42 2.533 2.782 2.785 99.18 91.70 2.334 2.710 2.900 99.56 91.21 2.136 2.535 fig.9 shows the elevation directivity patterns at the first resonance frequency at  0 and  90 . fig.10 shows the three dimension radiation pattern of the modeled dipole at the same frequency. it is clear that the antenna parameters and its resulting radiation characteristics are acceptable for the proposed applications. fig.5. the tent function with side length, l and the starting angle, θ. fig.6. an enlarged copy of fig. 4d. the two circles shown indicate that, at the 4 th iteration level the resulting structure is not a fractal anymore, since two same points in space have been visited twice. fig.7. the layout of the modeled tent fractal antenna with respect the coordinate system. fig.8. the return loss response of the tent fractal dipole antenna after frequency scaling to 2.45 ghz. jawad k. ali al-khwarizmi engineering journal, vol. 4, no. 3, pp 57-65 (2008) 63 fig.9. the elevation patterns directivity display at a frequency of 2.46 ghz. fig.10. the 3d radiation pattern at a frequency of 2.45 ghz. 5. conclusions the tent fractal dipole antenna has been presented in this paper, analyzed in details, and simulated. the antenna seems promising to be used in multi-function communication systems due to its good multiband response. simulation results assure the multiband operation of this antenna with accepted radiation characteristics for the proposed applications. results showed that the modeled dipole antenna has reasonable antenna parameters at resonance. much work has to be carried out to investigate its counterpart monopole antenna. the effect of substrate parameters on antenna performance has to be investigated when printing the antenna on a microstrip substrate. jawad k. ali al-khwarizmi engineering journal, vol. 4, no. 3, pp 57-65 (2008) 64 6. references [1] b. b. mandelbrot, “the fractal geometry of nature,” w. h. freeman and company, 1983. [2] k. falconer, “fractal geometry; mathematical foundations and applications,” second edition, john wiley and sons ltd., 2003. [3] s. e. el-khamy, “new trends in wireless multimedia communications based on chaos and fractals,” 21 st national radio science conference (nrsc2004), pp. inv1 1 -25, 1618 march 2004. [4] h. n. kritikos and d.l. jaggard, (eds.), “recent advances in electromagnetic theory: on fractal electrodynamics,” springer-verlag, new york, 1990. [5] d. l. jaggard, "fractal electrodynamics: wave interactions with discretely selfsimilar structures," in electromagnetic symmetry, c. baum and h. kritikos, eds., taylor and francis publishers, 1995. [6] d. l. jaggard, “fractal electrodynamics: from super antennas to super lattices,” fractals in engineering: from theory to industrial applications, springer, london, 1997. [7] g. kumar, “broadband microstrip antennas,” artech house, inc., 2003. [8] n. cohen, “fractal’s new era in military antennas,” journal of rf design, pp. 12-17, april 2005. [9] c. puente, j. romeu, r. pous, j. ramis, and a. hijazo, “small but long koch fractal monopole” electronic letters, vol.38, no.1, january, 1998. [10] k. j. vinoy, k. a. jose, v. k. varadan, and v. v. varadan, “hilbert curve fractal antenna: a small resonant antenna for vhf/uhf applications,” microwave opt. technol. lett., vol. 29, no. 4, pp. 215–219, may 2001. [11] j. p. gianvittorio and y. rahmat-samii, “fractal antennas: a novel miniaturization technique and applications,” ieee antennas and propagation magazine, vol. 44, no. 1, pp.20-36, february 2002. [12] g. konstantatos, c. soras, g. tsachtsiris, m. karaboikis, and, v. makios, “finite element modeling of minkowski monopole antennas printed on wireless devices,” electromagnetics, taylor and francis, emg13571, pp. 1-13, 2004. [13] j. zhu, a. hoorfar, and n. engheta, “peano antennas”, ieee antennas wireless propagat. lett., vol. 3, pp. 71-74, 2004. [14] m. r. haji-hashemi, h. mir-mohammad sadeghi, and v. m. moghtadai, “spacefilling patch antennas with cpw feed” progress in electromagnetics research symposium, pp. 26-29, march 26-29, cambridge, usa, 2006. [15] c. t. p. song, p.s. hall, and h. ghafourishiraz, “shorted fractal sierpinski monopole antenna,” ieee trans. antennas and propagat., vol. 52, no. 10, pp. 25642570, oct. 2004. [16] r. azaro, g. boato, m. donelli, a. massa, and e. zeni, “design of a pre-fractal monopolar antenna for 3.4-3.6 ghz wimax band portable devices,” technical report dit-05-057, university of trento , august 2005. [17] m. k. tahir, “combined fractal dipole wire antenna” loughborough antennas and propagation conference, 2 -3 april 2007. loughborough, uk, pp. 65-68. [18] k. j. vinoy, k. a. jose, v. k. varadan, and v. v. varadan, “resonant frequency of hilbert curve fractal antennas,” in proc. dig. 2001 ieee ap-s int. symp., boston, ma, 2001, pp. 648–652. [19] h. peitgen, h. jürgens, d. saupe, “chaos and fractals,” new frontiers of science, second edition, springer-verlag new york, 2004. [20] w. hödlmayr, “fractal antennas”, antennex, online issue no. 81, january 2004, webmaster@antennex.com. [21] d. dubost, “flat radiating dipoles and applications to arrays,” research studies press, john wiley and sons ltd., 1981 mailto:webmaster@antennex.com jawad k. ali al-khwarizmi engineering journal, vol. 4, no. 3, pp 57-65 (2008) 65 هوائي جذيذ ثنائي القطب مطبوع مبني على اساس الترتيب الهنذسي الجزئي لتحويالت دالة الخيمة لتطبيقات االتصاالت الالسلكية جواد كاظم علي انجايؼح انتكُٕنٕجٛح/ قضى ُْذصح انكٓشتاء ٔاالنكتشَٔٛك الخالصة antenna printedيٍ انُٕع ثتائٙ انقطة انًطثٕع (multiband) ٚتى اصتؼشاض ْٕائٙ يصغش يتؼّذد انُطاق انتشدد٘,فٙ ْزا انثذث dipoleقتََشِح يضتُذ ػهٗ اصاس انتشتٛة انُٓذصٙ انجزئٙ. ػهٗ اَّ يشّشخ نإلصتؼًاِل فٙ تطثٛقاِخ االتصاالخ انالصهكٛح ًُ ٌّ تصًَٛى انٕٓائٙ ان إ fractal geometryنتذِٕٚم دانح انخًٛح (tent function) َٙانتٙ ٚتصف تٓا ْزا (انفضاء)تَْضًُخ خاصٛح ايالء انفشاؽ . يٍ انًضتٕٖ انثا َْتاا اإاِل ااثش فٙ يضاداخ اثش إَضغاااًا تى دضاب األداء انُظش٘ نٓزا انٕٓائٙ تاصتخذاو انذقٛثح انثشيِجٛح انًتٕفشِج . انتشتٛة انُٓذصٙ تئ اظٓشخ . (mom), ٔانتٙ تضتُذ فٙ اجشاء انتقٛٛى تاصهٕب انًذاااج ػهٗ اشٚقِح اٚجاد انؼزٔو zeland, يٍ اَتاا يؤصضح ie3dتجاسٚا َى فٙ َفش تشدِد انتصًٛىِ ًّ ٔػالٔج . انُتائئ تبٌ انٕٓائٙ انًقتشح ٕٚفش تخفٛضا اثٛشا فٙ انذجى ِ يقَاسَحَ تانٕٓائٙ انثُائٙ انقطة انتقهٛذ٘ انًص قتََشَح ًٚتهَك صهٕاا يتؼّذد انشٍَٛ يغ ادتفاظّ تًٕاصفاخ اشؼاع يُاصثح فٙ َذاء اَطقح انَشٍَٛ ًُ ٌّ انتصًَٛى ان ْٔزا َْٚجؼُم انٕٓائٙ ثُائٙ , ػهٗ فب يُاصثا نإلصتؼًاِل فٙ َظًِح االتصاِل يتؼذدِج انٕظائَف انذذٚثحَ راخ االدجاو (monopole َٔ َظٛشِ االداد٘ انقطة )انقطة انًقتشح .انًصغشج studying the flowability of (zno – cuo/ al2o3) catalyst through hopper before tableting process al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 5, no. 4, pp 18-24 (2009) studying the factors effect on the flowability of (zno – cuo/ al2o3) catalyst with blending of different lubricants through hopper malek m. mohammed * mazin a. h. radhi ** ali yasseen nasir * * department of chemical engineering/al-khwarizmi college of engineering/ university of baghdad ** al-rayah state company (received 18 march 2008 ; accepted 21 may 2009 ) abstract one of the most important problems in tablet process is to control the flow of the catalyst through the hopper; controlling the flow can be done either by changing the size of particles or added the different lubricant (stearic acid, starch, graphite) or blending of different lubricants. the study showed that we can control (increase or decrease) on the flow of the catalyst through the hopper by blending different lubricants for the constant percentage. the flow increasing when particles size (0.6 mm) and then decrease with or without lubricants, no effect on flow when particles size lower than (0.2 mm) with use that lubricants, and good flow on (0.4 mm) when use stearic acid and starch. keywords: catalyst, hopper, tablet machine, and powder blending. 1. introduction the catalyst used in this research was (zno – cuo / al2o3) which was in exyrogel phase, green color, non cohesive powder. this catalyst is calcined after tableting process to become finished catalyst zinc – copper over gama alumina (zn – cu / al2o3) in gray color. adding lubricants to catalyst is important to improve the flowing of the catalyst through the hopper and facilitating the tableting process in the tablet machine [1]. the lubricants affect the flow; compaction; and ejection behavior. some of lubricants will decrease the flow and decrease ejection; others such as graphite will improve all the flow and ejection [2]. in the mixing of solid particles, the following three mechanisms may be involved [3]: (a) convective mixing, in which groups of particles are moved from one position to another, (b) diffusion mixing, where the particles are distributed over a freshly developed interface, and (c) shear mixing, where slipping planes are formed. lubricant levels are a delicate balance between achieving good flow and achieving good compressibility. often, there is no magic amount of lubricant or post addition blend time that will account for variations in the excipients or the lubricant itself. by monitoring lubrication real time, physical characteristics of powder flow and tablet quality can be determined predicatively. the effect of lubricant addition to a uniform material can be clearly identified with thermal effusively. thermal effusively relates to a material’s ability to transfer heat. when magnesium stearate coats the particles, it causes the density of the granulation blend to increase, and the heat to transfer more readily. this is measured through the increase in effusively after the lubricant is added. by monitoring the blend lubrication states in advance, operators can take preventative action taken during blending or use the information upstream and initiate appropriate actions to produce quality tablets. the lubricant blending processes is an important component in malek m. mohammed al-khwarizmi engineering journal, vol. 5, no. 4, pp 18-24 (2009) 19 the development and scale-up of process applications [4]. lubricants typically used in tableting operation are graphite, starch, talc, stearic acid and others [5]. figure (1) [6] illustrates the blending of the particles with different lubricants which are very important in flow behavior of the catalyst, (1.a) shows the small particles with lubricants which have same particles size, (1.b) shows the medium particle sizes with lubricants without change in size, (1.c) shows the large particles with lubricant. fig.1. particles – lubricants mixture [6] the effect of lubricants on catalyst as tabulated in table below: table 1, effect of lubricants on catalyst application [7] lubricants effectiveness application on catalyst stearic acid good starch not effect graphite excellent magnesium stearate has disadvantage effect on flowability of powder, but when using stearic acid will give improvement in the flowability fig. (2) [8]. the aim of the study is to show the effect of flow (zno – cuo / al2o3) catalyst by using different types of lubricants (stearic acid, starch and graphite) with blending of them, to show their effects on the mass flow of the catalyst through the hopper. lubricant content of (11 %) by weight were used. the time of mixing is greater than two minutes to ensure the lubricants blending with catalyst [9]. fig.2. effect stearic acid on powder flowability [8] 2. experimental work 2.1. lubricants blending in present investigation a batch blending process was used. a typical batch blending system is shown in figure (3). the basic components are a blender, one or more portable or stationary containers, and a chute to a process, e.g., a tabletting press [10]. the blending time of the lubricant was about 2 – 5 minutes [11]. fig.3. lubricants blender 2.2. catalyst flow in this research a special hopper was used to measure the flow of catalyst (which has the same dimensions of the hopper in the "al – rayah state company" which is used in the tablet machine) as shown in figure (4). lubricant a lubricant b malek m. mohammed al-khwarizmi engineering journal, vol. 5, no. 4, pp 18-24 (2009) 20 fig.4. special hopper the mass flow rate of powder (g/s) was measured using the flow procedure: 1weighing the catalyst (w). 2allowing the catalyst to pour through the hopper, and calculate the time (t) needed for the catalyst to drain. mass flow rate = t w ... (1) lubricants were used as additives to the catalyst. three different types of lubricants (stearic acid, starch, and graphite) were prepared and with blending of these types at (11 %) weight percentage, (stearic acid + starch, stearic acid + graphite, starch + graphite, and stearic acid + starch + graphite), the procedure was as follows: 1weigh a sample of cut used (w). 2calculate weigh of lubricant content percentage used (wl) which mixed it with the catalyst, for example, when used (11 %) of lubricant: lw =   w w           11.01 ... (2) 3mixed the catalyst with lubricant and weigh them (wm). 4allowing the mixture to pour through the hopper, and calculate the time (t) for the mixture to drain. mass flow rate = t wm ... (3) three measurements were made for the catalyst and the mean value is taken as the true mass flow rate. 3. results and discussion: from figures (4 – 7), it is clear that by blending of lubricants, can control the mass flow through the hopper, graphite always lowers the flow, starch promotes the flow, and stearic acid has a moderate effect (positive) on the flow. it is clear that blending starch and stearic acid will give the highest mass flow rate (comparing with the other lubricants' blending), that is due to non – cohesiveness nature of starch. graphite lowers the mass flow rate because it is molecules form layers over lap over another layers [2]. lubricants contribute significantly to agglomerate strength, lubricants through the reduction of particle-particle friction to allow lower void fraction and closer particle contact. lubricants are most relevant to pressure methods of size enlargement where they may also act as mold release agents [7]. figures (5 – 8) show that, the mass flow rate at (0.6 mm) reach to the maximum value because the size of catalyst particles increased the effect of lubricants in the flow becomes clear than the cut of small size., and then fall down because the flow depend mostly on the particles size of catalyst, the diameter of hole of the hopper which is (2 cm) is fixed and the size of particles became larger (0.72 mm), therefore, the particles were crowded and do not able to flow through hopper. therefore the resistance of flow will be high, but generally the catalysts have good flow rate comparing with the results of figure (9). the adhesion increases with increase contact area [12]. malek m. mohammed al-khwarizmi engineering journal, vol. 5, no. 4, pp 18-24 (2009) 21 0 20 40 60 80 100 120 140 160 180 200 0 0.2 0.4 0.6 0.8 1 1.2 average particles diameter (m)×10 3 m a s s f lo w r a te ( k g /s )× 1 0 3 stearic acid starch stearic acid & starch fig.5. effect particles sizes on flow with blends (stearic acid & starch) 0 20 40 60 80 100 120 140 160 180 0 0.2 0.4 0.6 0.8 1 1.2 average particles diameter (m)×10 3 m a s s f lo w r a te ( k g /s )× 1 0 3 stearic acid graphite stearic acid & graphite fig.6. effect particles sizes on flow with blends (stearic acid & graphite) 0 20 40 60 80 100 120 140 160 180 200 0 0.2 0.4 0.6 0.8 1 1.2 average particles diameter (m)×10 3 m a s s f lo w r a te ( k g /s )× 1 0 3 starch graphite starch & graphite fig.7. effect particles sizes on flow with blends (starch & graphite) 0 20 40 60 80 100 120 140 160 180 200 0 0.2 0.4 0.6 0.8 1 1.2 average particle diameter (m)×10 3 m a s s f lo w r a te ( k g /s )× 1 0 3 stearic acid starch graphite stearic acid & starch & graphite fig.8. effect particles sizes on flow with blends (stearic acid & starch & graphite) 0 20 40 60 80 100 120 140 160 0 0.2 0.4 0.6 0.8 1 1.2 average particles diameter (m)×10 3 m a s s f lo w r a te ( k g /s )× 1 0 3 fig. 9. effect the particles sizes on the flow (without lubricants) figures (10 – 13) show that the lubricants blend was improved the flowability of catalyst before distribution comparing to the previous batches containing lubricants [13]. . (stearic acid + starch) stearic acid starch 167.609168.038 175.8 100 110 120 130 140 150 160 170 180 mass flow rate (kg/s)×103 fig. 10. mass flow rate of blends (stearic acid & starch) lubricants for catalyst before distribution malek m. mohammed al-khwarizmi engineering journal, vol. 5, no. 4, pp 18-24 (2009) 22 . (stearic acid + graphite) stearic acid graphite 112.784 168-038 146.7 100 110 120 130 140 150 160 170 180 mass flow rate (kg/s)×103 fig.11. mass flow rate of blends (stearic acid & graphite) lubricants for catalyst before distribution . (starch + graphite) starch graphite 112.784 167.609 135.6 100 110 120 130 140 150 160 170 mass flow rate (kg/s)×103 fig.12. mass flow rate of blends (starch & graphite) lubricants for catalyst before distribution . (stearic acid + starch + graphite) stearic acid starch graphite 112.784 167.609168.038 160.5 100 110 120 130 140 150 160 170 mass flow rate (kg/s)×103 fig.13. mass flow rate of blends (stearic acid & starch & graphite) lubricants for catalyst before distribution 4. conclusions 1the flow of catalyst (with or without lubricants) through the hopper depends upon the particles size, the flow increases with particles size until (0.6 mm) and then decrease. 2the flow of catalyst through the hopper can be controlled by blending different types of lubricants, e.g. (stearic acid, starch, and graphite). 3the lubricants (stearic acid, starch, and graphite) show low effect on flow when particles size lower than (0.2 mm). 4stearic acid and starch have good lubricant properties when particles size more than 0.4 mm. nomenclature t the time of drain catalyst (s) w weight of catalyst (kg) wl weight of lubricant percentage (kg) wm weight of catalyst – lubricant mixture (kg) 5. references [1] little, a. and mitchell, k. a., "tablet making", 1963. [2] komarek, k. r., "selection binders and lubricants for agglomeration processes", chemical engineering, vol. 74, december 4, p. 154 – 155, 1967. [3] coulson and richardson, "chemical engineering" vol. 2, p.30, butterworthheinemann/ 2002 (5 th ed.). [4] "nir & blend/dose uniformity testing", meeting fda requirements, june, 2005. [5] jon, e. browning, "agglomeration: growing large in application and technology", chemical engineering, vol. 74, december 4, p. 151 – 153, 1967. [6] hardo, p. j., "manufacturing by selective laser sintering", by internet. [7] j. c. williams, and t. allen, "handbook of powder technology", vol. 1, "particle size enlargement", elsevier science publishers, 1980 [8] cunningham, c. r. and scottergood, l. k., "optimizing lubricant usage in direct malek m. mohammed al-khwarizmi engineering journal, vol. 5, no. 4, pp 18-24 (2009) 23 compression hydrochlorothiazide formulation containing a plastically deforming excipient". [9] coulson and richardson, "chemical engineering" vol. 2, p.33, butterworthheinemann/ 2002 (5 th ed.). [10] kirk – othmer "encyclopedia of chemical technology", vol. 19, john wiley & sons, inc./ 2002 (4 th ed.). [11] mukesh c. gohel, rajesh k. parikh, bansari k. brahmbhatt, and aarohi r. shah, aaps pham. sci. tech., february 8, article 13, 2007. [12] lieberman, a., chemical engineering, april 10, p. 209 – 218, 1967. [13] charles r. cunningham, and laura k. scattergood, american association of pharmaceutical scientists, october, 2000. 2418، صفحت 4، العذد 5مجلت الخوارزمً الهىذسٍت المجلذ مالك مصطفى محمذ (2009) 24 دراست العوامل المؤثرة على اوسٍابٍت العامل المساعذ (al2o3  (zno – cuo/ مع مسج مسٌتاث مختلفت خالل القمع *علً ٌاسٍه واصر** مازن عبذ الهادي راضً* مالك مصطفى محمذ جبمعت بغذاد / كهيت انهىذست انخىارزمي/ قسم انهىذست انكيميبئيت االحيبئيت * شركت انرايت انعبمت سببقب ** الخالصت انسيطرة عهً انجريبن يمكه ان يعمم امب بخغيير حجم , احذي اهم انمشبكم في عمهيت انكبس هي انسيطرة عهً جريبن انعبمم انمسبعذ خالل انقمع انذراست بيىج بأوىب يمكه ان وسيطر . او مسج مسيخبث مخخهفت (انىشب و انكرافيج, حبمض انسخريك)جسيئبث انعبمم انمسبعذ او أضبفت انمسيخبث انمخخهفت ( مم0,6)انجريبن يسداد عىذمب حجم انجسيئبث . عهً جريبن انعبمم انمسبعذ خالل انقمع بمسج انمسيخبث انمخخهفت نهىسب انمئىيت انثببخت (زيبدة او وقصبن) وجريبن جيذ في , مع اسخعمبل حهك انمسيخبث ( مم0,2)ال حأثير عهً انجريبن عىذمب يىخفض حجم انجسيئبث عه , وبعذ رنك يخىبقص مع او بذون انمسيخبث . عىذ اسخعمبل حبمض انسخريك وانىشب ( مم 0,4) al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 6, no. 4, pp 52–61 (2010) design and implementation of iraqi virtual library bahaa i. kazem* mohammed najm abdulla** jalal b. raouf*** jean-noël colin**** barry levine***** * center of continuous learning/ university of baghdad email: drbahaa@gmail.com ** department of computer engineering and information technology/ university of technology email: mustafamna@yahoo.com *** college of administration/ university of baghdad email: jalal_bassim@hotmail.com **** faculty of computer science/ university of namur email: jnc@info.fundp.ac.be ***** department of computer science/ university of san francisco state email: levine@sfsu.edu (received 1 april 2008; accepted 11 november 2010) abstract in developing countries, individual students and researchers are not able to afford the high price of the subscription to the international publishers, like jstor, elsevier,…; therefore the governments and/or universities of those countries aim to purchase one global subscription to the international publishers to provide their educational resources at a cheaper price, or even freely, to all students and researchers of those institutions. for realizing this concept, we must build a system that sits between the publishers and the users (students or researchers) and act as a gatekeeper and a director of information: this system must register its users and must have an adequate security to ensure that only the affiliated students are able to access its services. it also needs to have security and trust mechanisms built-in for commercial partners to accept their connections. this paper describes the work done on the design and implementation of the ivl (iraqi virtual library). keywords: ivsl, ivl, virtual library, iraqi virtual library, iraqi virtual science library, authentication 1. introduction the term “virtual library” may be interpreted very differently and in any study of the literature the reader must be aware of the myriad of interpretations that are applied to it. the literature abounds in terms that might have provided inspiration: virtual library (like the ivsl [1] and the ivl), library without walls, networked library, desktop library, logical library, information nerve center, information management center, digital library, and electronic library [2]. the virtual library is an internet website that acts as a gatekeeper and a director for information. it purchases the expensive licenses required to access the publishers’ resources and then it enables its users to access the publishers through it freely or at marginal cost, therefore its users will not need to purchase the licenses from the publisher. it electronically manages user access and passes the appropriate credentials to the resource provider [3]. therefore it must have a user management functionality to manage user information, together with appropriate authentication and authorization mechanisms to this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ bahaa i. kazem al-khwarizmi engineering journal, vol. 6, no. 4, pp 52 – 61 (2010) 53 validate user credentials and access to resources. this system enables large organizations like universities and educational institutions to build a virtual library and provide its services only to the organization’s members like students. the origin of the ivl code is from the e-science-library project by dr.jean-noel colin, with this project, we contributed to the development of the escience-library by the use of open collaborative tools and we called it ‘iraqi virtual library’ to distinguish it from the currently working iraqi virtual science library (ivsl) which is not an open source software and is not available for development, while the ivl is open source and is available for continuous development at http://escience-library.dev.java.net. in 2007 the ivl project (https://e-science-library.dev.java.net/) was deployed as the avsl project (http://avsl.aua.am/avsl/) at american university of armenia (aua). since the vsl system is based on extended java and web tools some difficulties were encountered by the system administrator due to the lack of experience in these technologies. with assistance from the java.net project administrators the system was successfully deployed. during this redeployment the project documentation was further enhanced for future ports. the avsl project will be utilized first by aua students and faculty. subsequently, the project will be housed within the armenian academy of sciences to support scientific research within the entire country. the ivl system primarily relies on java technologies, ezproxy server for the authenticaiton with commercial providers, relational database and ldap for the user authentication. figure (1) shows the main page of the ivl. the ivl sits between the publishers (that provide or sell access to the digital resources) and the users. therefore, the virtual library manages two types of connections: one with the publishers and the other with its users and it should provide security mechanisms for both of them. these security mechanisms make the interior structure of the virtual library very complicated and consist of various technologies. the publishers protect access to their information resources by different techniques therefore the virtual library must provide the suitable connection mechanism with each publisher. for convenience purposes, the ivl system also offers a bulleting board functionality that allows authorized users to publish short news messages that are displayed on the main page of the website. the rest of this paper is structured as follows: section ii describes the security aspects of the ivl system; section iii presents the user management functionalities. section iv describes the news bulleting board included in the platform; section v and vi give more details on the design and development process, and finally, some concluding remarks are provided in section vii and viii. 2. the proposed ivl system operations the designed ivl system is depicted by figure 1, while figure 2 shows the main page of this system, the system processes are performed as the following steps:a. the user accesses the ivl system. b. the user tries to log in. c. the ivl’s application server checks the availability of the user account in the ldap realm (directory server). it then authenticates the user, authorizes him to access the publishers, and/or authorizes him to the admin or editor role according to the group in which he belongs to. d. the ivl system uses the java naming & directory interface (jndi) to access the ldap when the admin user enacts the users’ registration information. e. the ivl system uses the jndi to lockup for the mysql server and uses the java database connectivity (jdbc) to access it when the editor user enacts the news database. f. when the user requests one publisher, ezproxy forwards this request to the appropriate publisher and when it receipts the result, it returns the result back to the user’s web browser. ezproxy will continuously rewrite the publisher url’s links to continuously keep itself between the user and the publisher. the publisher will see the request as coming from the ivl system’s ip address which it knows in advance and permits it [4]. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ bahaa i. kazem al-khwarizmi engineering journal, vol. 6, no. 4, pp 52 – 61 (2010) 54 fig.1. the ivl system operations. fig.2. the main webpage of the ivl system. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ bahaa i. kazem al-khwarizmi engineering journal, vol. 6, no. 4, pp 52 – 61 (2010) 55 3. the security of the ivl system in the ivl distributed system, there are two types of connections, thus its security mechanisms are divided into two types accordingly:  securing the virtual library – user connection  securing the virtual library – publisher connection how these two types of security have been implemented and what security technologies are used to secure them will be discussed in the following sections. a. the virtual library – user connection in ivl distributed system, code representing business operations is hosted on the server. a client request acts as a trigger to execute server code that has the potential to perform critical operations that manipulate sensitive data. it is important to distinguish requests that can be trusted from those that cannot. the server must enforce security based on who is attempting to run the code, and that means being able to verify the identity of the caller. j2ee provides the declarative and programmatic security mechanisms which are used to enable the ivl server to authenticate the user. and the secure encrypted communication is used to enable the user to authenticate the ivl server and encrypt his credentials before sending it to the ivl server [5]. 1) declarative security because all applications share the following security operations and much of the work is similar regardless of the application being written, it is possible to abstract security away into a framework.  receives a request.  authenticates the caller.  checks the caller's authorization.  grant or deny access. by using declarative security, an application can specify via parameters defined at deployment time (i.e., web.xml) the level of security that a given resource needs, and these security constraints are enforced by the web application container at runtime. this allows the developer to completely separate business and security concerns when designing his application. this declarative approach is reasonably flexible and easy to use. it is following the role-based access control (rbac) model [] which is based on two main concepts: resources and roles.  resources are the entities that need to be protected;  roles define permissions to access and/or manipulate the resources. roles are assigned to the users according to the level of permission they need to access the resources. different users will be given different levels of access based on the role they are assigned for the application. in theory it would be possible to check every single access to the site based on the user's credentials, but for thousands of users, managing individual user access quickly becomes difficult. instead, what happens is that users are assigned to a "role". each resource in the site is then accessible only to certain roles [5]. in the ivl platform, we define three different roles (actors): 1. a ‘regular’ user is any user who reaches the ivl portal, authenticated or not, he can do the following: a. access the public ivl website b. access to the publishers c. login to the ivl website d. logout from the ivl website 2. an ‘admin’ user, who is allowed to perform the following users registration operation: a. create user b. modify user c. delete user d. suspend user e. activate user f. upload user data 3. an ‘editor’ user, who is allowed to perform the following bulletin board management operations” a. create news b. modify news c. delete news d. archive news users may also have a status: 1. an active user is known to the system and this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ bahaa i. kazem al-khwarizmi engineering journal, vol. 6, no. 4, pp 52 – 61 (2010) 56 authorized to perform any action granted by his role 2. a suspended user is known to the system, but all permissions have been suspended temporarily. 2) programmatic security programmatic security is security mechanisms that are built in the application code itself. it is used to apply finer grain control in the application, and allow for object-level permissions. it allows the application to obtain information about the caller or the caller's role membership at runtime and apply different logic based on what is discovered [4]. 3) secure encrypting communication if the user wants to send his credentials (user name, password), it has better be encrypted to be protected against eavesdropping. however, there is no point in encrypting the data if the endpoint (the ivl system) itself is not trusted. in other words, before the user sends private data, he should first ensure that he is talking to the ivl system. this is the opposite authentication that was discussed earlier, where the ivl authenticated the user. now, the user has to authenticate the ivl server before sending the data. to achieve this, we are implementing a solution based on x.509 certificates for server authentication. several organizations can be used as trusted cas to deliver and validate site certificates, like verisign for instance. certificates issued by verisign are globally recognized, and verisign's public key gets distributed with commercial client and server software such as browsers and web servers. there is thus no need to propagate a custom ca certificate to all potential clients, which simplifies the implementation and key management. we rely on the https protocol for the server authentication phase. when the client (the user) connects to the ivl server through his browser, the server sends its certificate, so the user can check and validate it. further a session key can be negotiated securely. from that point on, data can be encrypted or signed using the shared session key (symmetric encryption). this is essentially what ssl does, although it's a little more complex than that [5]. b. the virtual library–publisher connection currently, many publishers manage access to electronic resources through the control based on clients ip addresses, an approach that makes sense when users are connecting from the university network. but relying upon ip addresses does not work for members of the community when they are at home, or when they are on leave, or traveling. similarly, publishers need reliable authentication and authorization schemes that can distinguish legitimate users from others seeking unauthorized entry [6]. therefore the ivl system uses the ezproxy® authentication and access software that acts as a secure gateway between the users and the publisher services. the ivl system easily provides a page containing appropriately tailored links for the publishers. after the user logs in the ivl system and clicks on a link for a publisher, the java servlet uses the programmatic security to get the user’s name and then it computes the md5 message digest of the user’s name, the time of request, and the md5 password, then it sends this digest along with the user’s name, time of request, and specified publisher’s url as a ticket to the ezproxy server. after ezproxy server receives the ticket, it recalculates the md5 and authenticates the user only if that ticket is valid. after authentication, ezproxy server forwards the user’s request to the appropriate publisher. upon receipt of the information from the publisher, the proxy server dynamically rewrites the information and provides it for the user, so that the publisher sees the request as coming from the ezproxy server machine ip address. and because this machine exists within the university network as an authorized client for the publisher, access to the requested resource is granted. the most important advantage to ezproxy is that, no interaction or configuration is required from the end-user’s perspective [7]. 4. the user registration system in the ivl system, a lightweight directory access protocol (ldap) server is used to store the users’ information (user name, first name, last name, role type, e-mail, and password). a directory can ultimately be thought of as a very sophisticated address book in which entries can be associated with classes (or types) and where this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ bahaa i. kazem al-khwarizmi engineering journal, vol. 6, no. 4, pp 52 – 61 (2010) 57 entries are organized for efficient access. ivl system uses the ldap protocol to query the server, look up users’ names and validate their passwords. typically, ldap data are organized hierarchically, in the dit (directory information tree). the ivl directory has a single root node, with a second-level node for the university in which would be a list of the users of the ivl system. below the single root node, there is a second-level node, one for each group of the administrators, editors, and users. each user should be a member of one or more of those groups and will have its role. the members of the administrator group can modify the users list, the members of the editors group can modify the news, and the members of the users group can only access the publishers. there is a one-to-one mapping between the roles defined in the declarative security described above and the group membership. in fact, being member of one of the three groups automatically assigns the corresponding role to the user. this is due to the use of a ldap realm in the declarative security mechanisms implemented: when the user tries to log in, the ivl system uses the java declarative security with the ldap realm to check for the name, password, and the group of that user in the ldap server and upon successfully authentication, assigns the user the role corresponding to the group(s) the user belongs. but when the administrator user modifies the users’ list, the ivl system uses the java naming and directory interface to access the ldap and perform the required operations. the reasons for having specialized directory services and not just use an existing data-storage mechanism such as a relational database management system are: directories are optimized for read-only access. you look up entries in a directory far more often than you add or update entries. relational databases need to provide a balance between queries and update speed.  directories impose a structure on the data. all the entries have the same types of information in them. relational databases have a more general-purpose structure than directories. also, the restricted structure of a directory means that you don’t have to worry about issues such as using first normal form, as you do in a database.  directories are often distributed. this makes administration easier and allows user load on the servers to be distributed as well. the simplified structure of a directory is easier to replicate than the structure of a relational database.  directories are sorted. however, only one sorting structure exists, and directories do not have to be very good at dealing with advanced queries. this allows them to be simpler, cheaper, and easier to administer [8].  relying on a ldap server allows for a simpler integration in university infrastructure, since many of them already manage their users in such a directory. 5. the news publishing management system the ivl also provides a bulleting board functionality that allows authorized users to publish news for the whole ivl community. the ivl system uses the relational database management system mysql to store the newsrelated information and accesses it through the java database connectivity (jdbc) protocol. mysql server is designed to work in distributed environment, following the three-tier architecture (presentation, business, data)[9]. for independence between layers, the ivl system relies on the application server for the definition of the data source. it looks up the data source properties at runtime using jndi (java naming and directory interface). it also delegates to the application server the whole connection management and pooling. 6. the graphical user interface the ivl system uses the java server faces (jsf) for building the server side graphical user interface of its webpages. the java server faces provides a standard framework for building presentation tiers for web applications [10]. jsf brings rapid user interface development to server side java and provides much of the plumbing that jsp developers have to implement by hand [11]. jsf offers several advantages over traditional servlets and jsps:  it is a flexible and extensible framework, that supports the mvc paradigm, for better separation of interface and business logic development this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ bahaa i. kazem al-khwarizmi engineering journal, vol. 6, no. 4, pp 52 – 61 (2010) 58  it offers a wide variety of graphic components, together with powerful primitives to handle events, validate user input, and define navigation rules among the pages. the ivl system includes fifteen jsf pages [12]. the navigation between these pages is depicted by figure 3. fig.3. the navigation between the ivl system webpages. 7. the development environment because the codebase is publicly available, and because one of the goals of the ivl system is to contribute to the community, the concurrent version system (cvs) source code management have been used to contribute to the development of the ivl system at the java.net website http://escience-library.dev.java.net. in addition to the source code repository, this web site provides free tools for supporting collaborative development by a distributed team of developers [13]. direct communications between developers were managed via skype and email, due to the fact that developers were split around the world. [14]. this development mechanism provides high flexibility for the ivl and enabled the ivl to be developed, implemented and tested by different countries including iraq, armenia…etc. 8. design comparison between the ivl and ivsl projects table 1 demonstrates the comparison between the ivl project and the ivsl project design. 9. conclusions a in this paper, we have presented the design and implementation of the iraqi virtual library, a solution that allows governments and institutions (mainly universities) to this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ bahaa i. kazem al-khwarizmi engineering journal, vol. 6, no. 4, pp 52 – 61 (2010) 59 legally connect to scientific publishers and provide controlled access to the resources offered by those publishers to authorized members of the staff and users. b the same user registration system of the ivl system can be simultaneously adapted by the university to support services other than the access to the publishers’ resources. these services may include managing the admission to the university, recording the students’ information, managing the electronic learning management system. c the development of this system really enabled our institution to get access to a huge amount of scientific information that would otherwise be completely hidden and unreachable. this initiative definitely contributes to the spread of knowledge between countries. d from a technical perspective, this project has also been the occasion to learn and acquire in-depth knowledge on technologies that were not frequently used in our context. this acquired knowledge and skills will now benefit to the whole university community, being used in classes as well as the basis for further development of the ivl system. e indeed, the iraqi virtual library will now evolved and be integrated in a wider initiative aimed at proposing more and more integrated services through a single portal. table 1, comparison between the ivl project and the ivsl project design. ivl ivsl code open source code and will be in continuous development its code is not open for developers single sign on process single sign on process for accessing all publishers single sign on process for accessing all publishers registration the researchers at the supports institutions can apply to ivl by submitting an application by hand to the administrator, who verifies the applicant as a valid member of the institution and fills the application online. approved users can use the password they wrote in their application to access the ivl the researchers at the supported institutions can apply to ivsl by submitting an on-line application, which is sent to the registrar, who verifies the applicant as a valid member of the institution and approves or rejects the applicant. approved users are given a user name and password and can then access the ivsl news contains advance news presentation and editing system contains simple news presentation and editing system user registration system it uses ldap directory server for storing the users information unpublished access to publishers uses ezproxy server uses ezproxy server this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ abbreviations ivl iraqi virtual library ivsl iraqi virtual science library ldap light weight directory access protocol jndi java naming and directory interface jdbc java data base connectivity url uniform resource locator j2ee java 2 enterprise edition rbac role based access control http hyper text transfer protocol ssl secure socket layer md5 message digest dit directory information tree jsf java server faces jsp java server pages mvc model view controller cvs concurrent version system 10. references [1] url: https://www.ivsl.org. [2] jennifer rowley, “the electronic library”, facet publishing, london, 2002. [3] dj patil, james simon and susan cumberledge, “digital science libraries practical approaches to supporting science in developing countries”, un chronicle online edition, united nations, 2006. available: http://www.un.org/pubs/chronicle/2006/issue 3/0306p60.htm. [4] jalal b raouf, “design of iraqi virtual science library”, 2007. available: http://escience-library.dev.java.net. [5] jayson falkner, kevin jones“servlets and javaserver pages™: the j2ee™ technology web tier”, addison wesley, united state of america, september 19, 2003. [6] ira h. fuchs, “remote authentication and authorization for jstor”, chief scientist, jstor. vice president for computing and information technology, princeton university, september 8, 2006. available: url: http://www.jstor.org/about/remote.html. [7] url: http://www.usefulutilities.com. [8] james mcgovern,rahim adatia, yakov fain “java™ 2 enterprise edition 1.4 bible”, wiley publishing, inc., indianapolis, indiana, united states of america, 2003. [9] paul dubois, “mysql cookbook”, o'reilly, united states of america, october 2002. [10] william crawford, jim farley, “java enterprise in a nutshell, 3rd edition”, o'reilly, united states of america, november 2005. [11] david geary ,cay horstmann “core javaserver™ faces”, addison wesley, united states of america, june 15, 2004. [12] jalal b raouf, “ivsl platform”, 2007. available: http://e-sciencelibrary.dev.java.net. [13] url: https://www.dev.java.net/scdocs/ddcvs.ht ml. [14] dragutin petkovic, rainer todtenhoefer and gary thompson), “teaching practical software engineering and global software engineering: case study and recommendations”, the computer science departments of san francisco state university (sfsu) usa in conjunction with the university of applied sciences, fulda university, germany, 2005. available: http://librarymanagementgreen.dev.java.net . this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ )2010( 61-52 ، صفحة4، العدد 6مجلد مجلة الخوارزمي الھندسیة ال بھاء ابراھیم كاظم 61 تصمیم وتنفیذ المكتبة العراقیة االفتراضیة ***جالل باسم رؤوف **محمد نجم عبد اهللا *ابراھیم كاظم بھاء *****باري لیفاین ****جین نویل كولن جامعة بغداد/ مركز التطویر والتعلیم المستمر * drbahaa@gmail.com: البرید االلكتروني الجامعة التكنولوجیة/ قسم ھندسة الحاسبات وتكنولوجیا المعلومات ** mustafamna@yahoo.com: البرید االلكتروني جامعة بغداد/ كلیة االدارة واالقتصاد *** jalal_bassim@hotmail.com: البرید االلكتروني بلجیكا/ جامعة نامور / كلیة علوم الحاسبات**** jnc@info.fundp.ac.be: البرید االلكتروني الوالیات المتحدة االمریكیة /جامعة سان فرانسیسكو/ قسم علوم الحاسبات ***** levine@sfsu.edu: البرید االلكتروني الخالصة ,jstor( مثل العالمیة النشر دور في للتسجیل الباھضة التكالیف تحمل من والباحثین الطالب اغلب الیتمكن النامیة الدول في elsevier( اجل من النشر دور في وباحثیھا لطالبھا جماعي سجیلت على الحصول اجل من الدول ھذه وجامعات حكومات تسعى لھذا .فیھا الموجوده العلمیة المصادر على الحصول و النشر دار بین موقعة یكون نظام بناء یتطلب ذلك فان المسعى ھذا لتحقیق .مخفضة باسعار او مجانا العلمیة المصادر على الحصول من لیتمكنوا العالمیة امني نظام على یحتوي ان یجب كما المستخدمین بتسجیل النظام ھذا بقوم ان ویجب ,للمعلومات موجة و كبوابة النظام ھذا ویعمل )الباحث او الطالب( المستخدم یركز العمل ھذا .االفتراضیة المكتبة اسم النظام ھذا على یطلق .الجامعة لتلك التابعین والباحثین للطالب فقط متاحة النظام خدمات تكون ان یضمن لكي موثوق .االفتراضیة العراقیة المكتبة تصمیم على this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ al-khwarizmi!! engineering!!! journal al-khwarizmi engineering journal, vol. 6, no. 1, pp 101-112 (2010) في تصفیة میاه الشرب دراسة إمكانیة استخدام صخور النینفایت المحلیة منى فائق علي ة بغدادعجام/ كلیة الھندسة/ قسم ھندسة البیئة (received 9 november 2008; accepted 6 december 2009) :الخالصة تعان ا لالس ر حالی ل القط ة داخ ات العامل رب للمحط اه الش فیة می ي تص یح ف ي للتحقق من كفاءة صخرة النینفایت المحلیة عند استخدامھا كوسط ترش ا ف ة بھ ي تطویر واقع حال ھذه المحطات وجعلھا تواكب الزیادة الحاصلة في الكثافة السكان ار ف ا االنھ ي تعانیھ ویة الت ات العض وث بالملوث ادة التل یة كذلك مواجھة زی .والتي تعد المصادر الوحیدة لتغذیة كافة محطات التصفیة بالماء في القطر) دجلة والفرات(القطر ك ي تل تخدمة ف ل المس حات الرم ا لمرش ة العلی ن الطبق زء م تبدال ج تم باس ذه ت ویر ھ ویر او التح رة التط ذلك ان فك ل ب ت لتعم خرة النینفای ات بص المحط ط . كمرشحات ثنائیة الوسط اربون المنش ي الك ال، وھ ذا المج ي ھ ًا ف اح عالمی تخدم بنج رى تس واد اخ ع م ا م وبغیة التحقق من كفاءة الصخرة فقد تمت مقارنتھ .وفحم االنثراسیت ات وتمت المقارنة على اساس قابلیة ازالة مستویات العكورة المختلفة، وام ي محط ًا ف تخدمة حالی دالتھا المس وق مع ة تف كانیة استخدام معدالت ترشیح عالی .التصفیة داخل القطر ر ل القط ة داخ فیة العامل ات التص ابھة لمحط ري مش اس مختب ة بمقی ة بحثی اء محط ى بن م ال ذا القس ة . دعت الحاجة في اجراء تجارب ھ ى كاف وي عل وتحت .تخثیر وتلبید وترسیب اضافة الى منظومة الترشیح الوحدات التقلیدیة العاملة من احواض اني ) مرشحات(تكونت منظومة الترشیح في الدراسة الحالیة من اربعة اعمدة زجاجیة ود االول والث وى العم ث احت د بحی ي ان واح واٍز وف كل مت تعمل بش وق سم من صخرة النینفایت والكاربون المنشط وفحم االنثراسیت على الت ٢٠والثالث على وعة ف حات ٤٠والي وموض ل كمرش ي تعم ذا فھ ل وب ن الرم م م س م . سم لیعمل بذلك كمرشح احادي الوسط ٦٠ثنائیة الوسط بینما احتوى المرشح الرابع على الرمل فقط وبعمق د ت ة فق ة المطلوب ولغرض الحصول على المقارن .١٠٦وكذلك معامل االنتظام الذي بلغ ) ملم ٠.٨٢(استخدام الحجم المؤثر نفسھ لحبیبات المواد المستخدمة في الدراسة .، الكاربون، المنشط تیس، االنثرا اإلسالة، محطات والثنائیة األحادیةالمرشحات –النینفایت : المفتاحیة الكلمات المقدمة.١ خالل ١٩٨٧عام )٢(تم اكتشاف ھذه الصخرة من قبل النقیب ة جنوب محافظة قیامھ باعداد خارطة جیولوجیة مفصلة لمنطق االنواع الجدیدة من وفي بادئ االمر ساد االعتقاد بانھا احد. نینوى وھي صخرة موجودة في (ة یصخرة البورسیلینایت المحل . ]١٤[)الصحراء الغربیة ومنطقة الجزیرة غرب وجنوب العراق ولكن بعد دراستھا وتحلیلھا ومعرفة خواصھا تم عدھا صخرة ا الول مرة، وقد تمت تسمیتھا من قبل رسوبیة محلیة یتم اكتشافھ .ninivite([7, 2](باسم صخرة النینفایت [7,2])جاسم والنقیب( التركیبة التي تتكون منھا صخرة النینفایت، ) ١(یوضح الشكل اذ انھ یمثل شكًال شبھ بیضوي تتمركز السلیكا في وسطھ، وتكون kal2(so4)2محاطة بانطقة یتركز فیھا معدن االلونایت (oh)6 ومعدن الجاروسایتkfe3(so4)2 (oh)6 فضال عن ان ھذا . المعادن الحدیدیة وعلى التوالي باتجاه خارج الشكل االرتباط بین المعدنین والصخرة تكون نتیجة لعملیات تحلل ثانویة والصخور االخرى المرافقة لھا والتي marlلصخور المارل ت الكبریتیدیة التحلال(تعزى الى تفاعل حامض الكبریتیك -p(تحت الظروف االعتیادیة من ضغط وحرارة ) الحامضیة t([5]. ان التفاعالت تحت سطح االرض تكون مصدرا لغاز كبریتید والذي یتأكسد بعدئذ الى حامض الكبریتیك فوق h2sالھیدروجین مستوى المیاه الجوفیة بفعل نوع خاص من البكتریا المسماة )thio basillus thio oxidans .( ان التحلالت الكبریتیدیة الحامضیة تؤثر في المعادن الطینیة والكاربونات لصخور المارل مما ph(1.5-4.5)تحت ظروف واطئة من الدالة الحامضیة یؤدي الى حركة معظم العناصر وترسبھا في االنطقة الخارجیة .وبقاء السلیكا والتیتانیوم في الوسط . [5]تتركیبة صخرة النینفای )١(الشكل )2010( 112 101، صفحة 1، العدد 6مجلة الخوارزمي الھندسیة المجلد ليعمنى فائق 102 دروجین د الھی از كبریتی اث غ ة النبع دورة الطبیعی ون ال ولك ة ادن الطینی ي المع أثیره ف ك وت امض الكبریتی ى ح ده ال وتأكس وي دة تح اطق جدی اف من ة الكتش وث جاری ان البح تمرة، ف مس .ترسبات صخرة النینفایت المواد وطرائق العمل .٢ المنشودة من ھذه الدراسة ومنھا محاكاة افاألھدبغیة تحقیق laboratory(الواقع، فقد تم بناء محطة بحثیة بمقیاس مختبري scale pilot plant ( تعمل باسلوب الجاذبیة) ان أساسعلى ) جمیع محطات تصفیة الماء داخل القطر تعمل باسلوب الجاذبیة في وقد زودت بوحدات المعاملة التقلیدیة نفسھا والموجودة وحدات المحطة ) ٢(ویوضح الشكل .افةمحطات تصفیة المیاه ك .البحثیة :وحدات المحطة البحثیةاجزاء ١-٢ ان وحدات المحطة البحثیة تم تصمیمھا اعتمادا على المعادالت والمحددات والمعاییر التصمیمیة الموصوفة في .[6 ,8 ,9 ,10 ,11] المصادر المتوفرة :االرضي خزان الماء الخام -أ ) م١×م١×م١(تم استخدام ثالثة خزانات كل منھا بابعاد لغرض خزن الماء الخام الذي كان ینقل مباشرة من نھر دجلة .بوساطة عجلة حوضیة سم من سطح االرض ٢٠وضعت ھذه الخزانات على ارتفاع وجرى ربطھا مباشرة بمضخة ماء لنقل الماء من كل خزان عند .الى خزان الماء الخام المجھز للمحطةاجراء ایة دورة تشغیل :خزان الماء الخام المجھز للمحطة البحثیة -ب لتر ١٢٠ان الخزان مصنوع من مادة بالستیكیة وبسعة سم من سطح االرض لغرض تجھیز ٢٣٠ووضع على ارتفاع بوساطة ) حوض المزج السریع(الماء الخام الى حوض التخثیر .الجاذبیة زان بطواف ماء للحفاظ على ارتفاع ثابت جرى تزوید الخ عن ) over flow(ویتم التخلص من التصریف الزائد . للماء فیھ متصل بالخزان من مستوى الطواف ، ) valve(طریق صمام .یقوم بارجاع الماء الفائض الى الخزان االرضي للماء الخام ):حوض المزج السریع(حوض التخثیر -جـ × سم ١٠.٥(من الزجاج وبابعاد تم تصنیع ھذا الحوض وبفترة مكوث ھیدرولیكیة مقدارھا دقیقة ) سم١٠.٥×سم ١٠.٥ .واحدة الغرض الرئیس من استخدام ھذا الحوض ھو اضافة المادة بوساطة سحاحة مجھزة ) كبریتات االلمنیوم (المخثرة الكیمیاویة ة المواد الرملی(لھذا الغرض وذلك لجعل المواد المسببة للعكورة ویتم تجھیز ھذا الحوض . غیر مستقرة ومشتتة) العالقة والغرویة .بالماء الخام مباشرة من خزان الماء الخام المجھز للمحطة یكون ھذا الحوض مزود بآلة مزج سریع تتكون من محراك )stirrer ( متصل بستة مجاذیف)paddles ( وتدور بسرعة االلة المازجة دورة في الدقیقة، یمكن السیطرة على سرعة ٢٠٠ .یستخدم لھذا الغرض) regulator(بوساطة منظم سرعة ):حوض المزج البطئ(حوض التلبید -د تم تصنیع ھذا الحوض من الزجاج وبابعاد وبفترة مكوث ھیدرولیكیة مقدارھا ) سم٢٢×سم٣٠×سم٥٠( والغرض الرئیسي من استخدام ھذا الحوض ھو اعطاء . دقیقة ٣٠ ببة للعكورة غیر المستقرة والمشتتة والتي فرصة للمواد المس تكونت في حوض التخثیر ان تتلبد وتتراكم مع بعضھا لتكوین بفعل (مواد اكبر واثقل ، وعلیھ فان الماء كان ینتقل مباشرة .من حوض التخثیر الى حوض التلبید) الجاذبیة یكون حوض التلبید مجھزا بآلتي مزج بطيء وعلى التوالي احدة منھما من محراك متصل باربعة مجاذیف، وتتكون كل و ٤٠دقیقة وتدور الثانیة بسرعة / دورة ٦٠تدور االولى بسرعة دقیقة ، وتتم السیطرة على سرعتیھا بوساطة منظمي سرعة / دورة )regulators ( وحوض التلبید ھذا مرتبط بحوضي ترسیب .وبشكل مباشر :حوضا الترسیب -ھـ لزجاج وبابعاد تم تصنیع كل حوض من ا وبفترة مكوث ھیدرولیكیة مقدارھا ) سم٢٨×سم٣٤×سم٥٤( .دقیقة١٢٠ والغرض الرئیس من استخدام ھذین الحوضین ھو ترسیب المواد المتلبدة والمتكونة في حوض التلبید وعلیھ فان الماء كان .ینتقل من حوض التلبید الى حوض الترسیب مباشرة في مقدمتھ ) baffle(ان كل حوض ترسیب مزود بحاجز .لتوزیع الجریان بانتظام على المقطع العرضي الداخلي للحوض وكل حوض مزود في نھایتھ بثالثة صمامات، اثنین یستخدمان لتسلیط الماء على اعمدة الترشیح ویستخدم الثالث الخذ النماذج عند تشغیل ) over flow(والتخلص من التصریف الزائد .اقل مما ھو مصمم علیھالمحطة البحثیة بتصریف :الترشیح أعمدة -و تم استخدام اربعة اعمدة ترشیح مصممة لتعمل بشكل متواز االبعاد التصمیمیة لھذه ) ٣(وفي آن واحد، ویوضح الشكل ملم ٥٣یتالف كل عمود من انبوب اسطواني بقطر . االعمدة ملم مصنوع من الزجاج ومزود في اسفلھ بصمام ٩٥٠وارتفاع ریف الماء المعالج وتنظیم الجریان والجراء عملیة الغسل لتص .لمادة وسط الترشیح عند انتھاء أي دورة تشغیل ان الماء الخارج من كل صمام في حوض الترسیب یسلط على سم من النھایة العلیا ٥عمود الترشیح من االعلى، وعلى بعد .للعمود یوجد صمام لتصریف الماء خالل عملیة الغسل سم ٥٠سم، ٣٠تزوید كل عمود بصمامات على اعماق تم وتم ربطھا ببیزومترات . سم من النھایة العلیا للعمود ٩٠سم ، ٧٠ مثبتة على لوحة خشبیة لقیاس مستوى الماء على ارتفاعات مختلفة وقد تم اختیار . في العمود لتحدید فقدان الشحنة خالل دورة التشغیل سم وذلك ٦٠د الواحد بارتفاع مادة وسط الترشیح داخل العمو .لثنائیة واألحادیةلكفاءة ھذا العمق في المرشحات ا ن : العمود االول ون م وق ) ٢٠(یتك ت ف خرة النینفای ن ص م م س .سم من مادة الرمل) ٤٠( وق ) ٢٠(من یتكون : العمود الثاني ط ف اربون المنش ن الك سم م .سم من مادة الرمل) ٤٠( ن یتكون : العمود الثالث وق ) ٢٠(م یت ف م االنثراس ن فح م م س .سم من مادة الرمل) ٤٠( .سم من مادة الرمل) ٦٠(یتكون من : العمود الرابع )2010( 112 101، صفحة 1، العدد 6مجلة الخوارزمي الھندسیة المجلد ليعمنى فائق 103 )2010( 112 101، صفحة 1، العدد 6مجلة الخوارزمي الھندسیة المجلد ليعمنى فائق 104 ¾!! !œ!!ð!!! ! !! !! ! !œ!šƒ! ! !!œ!!!! ! ! !! ƒ! ƒ! ! !!œ!!œ!!! œ.!! یترلوحة المانوم ز مثبتة على ) سم١٢٠×سم٢٤٠(وھي لوحة خشبیة بابعاد انبوبا زجاجیا ١٦الجدار الى الخلف من المرشحات وتحتوي على ، ) المرشح(العمود ضغط الماء فيوذلك لقیاس ) بیزومترات( .لتحدید فقدان الشحنة خالل دورة التشغیل ةالنتائج والمناقش.٣ مستویات العكورة إزالة ١-٣ ھذه الدراسة تشغیل المحطة البحثیة بمستویات عكورة تم في طبیعیة، وجرى تحدید جرعة الشب الواجب اضافتھا بوساطة لكل ) حوض المزج السریع(فحص الجرة الى حوض التخثیر دورة تشغیل لتقلیل مستویات العكورة، وتثبیت مستواھا تقریبا قبل ات تسلیط المیاه الخارجة من حوضي الترسیب الى المرشح ومن ثم دراسة ازالة . االربعة في آن واحد، لتعمل بشكل متواز .مستویات العكورة المختلفة في كل مرشح ازالة مستویات العكورة الطبیعیة٢-٣ متوسط مستویات العكورة االولیة الداخلة ) ١(یلخص الجدول الى كل مرشح، ومتوسط مستویاتھا الناتجة في المیاه المعالجة في ات عند نھایة دورة التشغیل لمرشح الرمل ولمعدالت تلك المرشح حیث یالحظ في دورة . الترشیح المختلفة المستخدمة في الدراسة ان متوسط مستوى العكورة الطبیعیة االولیة في ) ١(التشغیل رقم وحدة، بحیث كانت المیاه المعالجة ذات ٩.٩اعلى مستوى لھا ٠.٨٧و ) ١(رشح وحدة بالنسبة للم ٠.٨٦متوسط مستوى عكورة ) ٣(وحدة بالنسبة للمرشح ٠.٩٣و) ٢(وحدة بالنسبة للمرشح , 88.8%)(أي بكفاءة ازالة ) ٤(وحدة بالنسبة للمرشح ١.١١و %90.6 , %91.2 ,%91.3. ان متوسط مستوى ) ١٦(بینما یالحظ في دورة التشغیل رقم ت وحدة بحیث كان ٣.٢العكورة االولیة كانت في اقل مستوى لھا وحدة بالنسبة ٠.٤٩المیاه المعالجة ذات متوسط مستوى عكورة وحدة ٠.٥٥و) ٢(وحدة بالنسبة للمرشح ٠.٥١و) ١(للمرشح أي بكفاءة ) ٤(وحدة بالنسبة للمرشح ٠.٦٣و) ٣(بالنسبة للمرشح لكل مرشح 84.7% ,84.16% , 82.86%, 80.36%)(ازالة .على التوالي لة من ھذا الجدول ان قیم ویتضح من البیانات المستحص وحدة ) ١(مستویات العكورة الناتجة في المیاه المعالجة لم تتجاوز . ولجمیع دورات التشغیل) ٣(,)٢(,)١(عكورة في المرشحات في حین ظھر بعض التجاوز الطفیف عن القیمة المذكورة في وھذا یؤكد الحقائق التي سبق ذكرھا عن مساوئ ھذا ). ٤(المرشح .الرملي االحادي مقارن باداء المرشحات ثنائیة الوسط المرشح وعمومًا فان متوسط مستویات العكورة الناتجة للمیاه المعالجة تحت الظروف المختلفة من مستویات العكورة االولیة واختالف معدالت الترشیح، لم تتجاوز مواصفات منظمة الصحة العالمیة وحدة او اقل، وھذا یدل ٥ والمواصفات الوطنیة العراقیة والبالغة .على ان المرشحات قد انتجت میاه بنوعیة جیدة ومرغوب فیھا بان المرشحات جمیعھا قد حققت كفاءة ) ٢(ویتبین من الجدول ازالة عالیة ولمستویات العكورة الطبیعیة االولیة المختلفة حیث لم عن ) ٢(، والمرشح % ٨٤.٦٩عن ) ١(تقل كفاءة االزالة للمرشح عن ) ٤(والمرشح % ٨٢.٨١عن ) ٣(والمرشح % ٨٤.٠٦ .ولجمیع دورات التشغیل التي تم اجراؤھا% ٨٠.٣١ كان االكفأ ) النینفایت+الرمل(ویتبین بشكل واضح ان مرشح في ازالة ) فحم االنثراسیت، الرمل+ الرمل (مقارنة بمرشحات مستویات العكورة االولیة ولمستویاتھا الطبیعیة المختلفة مع الكاربون + الرمل(التقارب الواضح في كفاءة ازالة مرشح ).النینفایت+ الرمل (من مرشح ) المنشط تغایر مستویات العكورة ) ٦( الى ) ٤(تبین االشكال من الناتجة في المیاه المعالجة من المرشحات مع الوقت لبعض دورات ل التشغیل علمًا ان عملیة التشغیل ھي الفترة بین عملیة غس .واخرى )2010( 112 101، صفحة 1، العدد 6مجلة الخوارزمي الھندسیة المجلد ليعمنى فائق 105 ! !! !¾! !! !œ!•!! !! œš! ! ! !!!! ! !œ!! !œ!!œƒ! !œ!! ! !! ! !œ!!œ!!ƒ!ƒ!! !œ!!! ! ! !!œ!! ! !! ! !! ! ! !!!! دورة التشغیل معدل الترشیح ساعة/م العكورة االولیة )وحدة عكورة( )وحدة(متوسط مستوى العكورة الطبیعیة الناتجة من المرشحات صخرة + الرمل النینفایت +الرمل الكاربون المنشط فحم + الرمل االنثراسیت الرمل ١.١١ ٠.٩٣ ٠.٨٧ ٠.٨٦ ٩.٩ ٤.٩ ١ ٠.٩١ ٠.٨٢ ٠.٧٦ ٠.٧٥ ٥.٨ ٢ ١.١٠ ٠.٩٣ ٠.٨٨ ٠.٨٦ ٩.٨ ٣ ٠.٩١ ٠.٨٣ ٠.٧٥ ٠.٧٣ ٥.٦ ٤ ٠.٥٩ ٠.٥٣ ٠.٤٧ ٠.٤٧ ٣.٦ ١٣ ٠.٦٠ ٠.٥٢ ٠.٤٦ ٠.٤٦ ٣.٣ ١٤ ١.١٣ ٠.٩٤ ٠.٨٩ ٠.٨٧ ٩.٨ ٧.٣ ٥ ٠.٩٤ ٠.٨٤ ٠.٧٦ ٠.٧٤ ٥.٦ ٦ ١.١٤ ٠.٩٥ ٠.٨٨ ٠.٨٧ ٩.٨ ٧ ٠.٩٥ ٠.٨٣ ٠.٧٧ ٠.٧٥ ٥.٥ ٨ ٠.٦٢ ٠.٥٥ ٠.٥٠ ٠.٤٨ ٣.٥ ١٥ ٠.٦٣ ٠.٥٥ ٠.٥١ ٠.٤٩ ٣.٢ ١٦ ١.٢٥ ٠.٩٧ ٠.٩٤ ٠.٩٢ ٩.٩ ٩.٨ ٩ ٠.٩٨ ٠.٨٥ ٠.٧٧ ٠.٧٦ ٥.٧ ١٠ ١.٢٤ ٠.٩٧ ٠.٩٤ ٠.٩٣ ٩.٨ ١١ ٠.٩٩ ٠.٨٥ ٠.٧٧ ٠.٧٦ ٥.٥ ١٢ ٠.٦٨ ٠.٥٥ ٠.٥٢ ٠.٥١ ٣.٦ ١٧ ٠.٦٦ ٠.٥٦ ٠.٥٢ ٠.٥٠ ٣.٥ ١٨ !¾! !! !œ•!! ! œš! ! ! !!!!ž!!! ! !œ!!ƒ!ƒ!! !œ!!! ! !!!œ!! œƒ! !! ! !! !œ! œ!!! œž!!! دورة التشغیل معدل الترشیح ساعة/م العكورة االولیة )وحدة عكورة( (%)كفاءة ازالة العكورة الطبیعیة الناتجة من المرشحات تالنینفای+ الرمل +الرمل الكاربون المنشط فحم + الرمل االنثراسیت الرمل ٨٨.٧٩ ٩٠.٦١ ٩١.٢١ ٩١.٣١ ٩.٩ ٤.٩ ١ ٨٤.٣١ ٨٥.٨٦ ٨٦.٩٠ ٨٧.٠٧ ٥.٨ ٢ ٨٨.٧٨ ٩٠.٥١ ٩١.٠٢ ٩١.٢٢ ٩.٨ ٣ ٨٣.٧٥ ٨٥.١٨ ٨٦.٦١ ٨٦.٩٦ ٥.٦ ٤ ٨٣.٦١ ٨٥.٢٨ ٨٦.٩٤ ٨٦.٩٤ ٣.٦ ١٣ ٨١.٨٢ ٨٤.٢٤ ٨٦.٠٦ ٨٦.٠٦ ٣.٣ ١٤ ٨٨.٤٧ ٩٠.٤١ ٩٠.٩٢ ٩١.١٢ ٩.٨ ٧.٣ ٥ ٨٣.٢١ ٨٥.٠٠ ٨٦.٤٣ ٨٦.٧٩ ٥.٦ ٦ ٨٨.٣٧ ٩٠.٣١ ٩١.٠٢ ٩١.١٢ ٩.٨ ٧ ٨٢.٧٣ ٨٤.٩١ ٨٦.٠٠ ٨٦.٣٦ ٥.٥ ٨ ٨٢.٢٩ ٨٤.٢٩ ٨٥.٧١ ٨٦.٢٩ ٣.٥ ١٥ ٨٠.٣١ ٨٢.٨١ ٨٤.٠٦ ٨٤.٦٩ ٣.٢ ١٦ ٨٧.٣٧ ٩٠.٢٠ ٩٠.٥١ ٩٠.٧١ ٩.٩ ٩.٨ ٩ ٨٢.٨١ ٨٥.٠٩ ٨٦.٤٩ ٨٦.٦٧ ٥.٧ ١٠ ٨٧.٣٥ ٩٠.١٠ ٩٠.٤١ ٩٠.٥١ ٩.٨ ١١ ٨٢.٠٠ ٨٤.٥٥ ٨٦.٠٠ ٨٦.١٨ ٥.٥ ١٢ ٨١.١١ ٨٤.٧٢ ٨٥.٥٦ ٨٥.٨٣ ٣.٦ ١٧ ٨١.١٤ ٨٤.٠ ٨٥.١٤ ٨٥.٧١ ٣.٥ ١٨ )2010( 112 101، صفحة 1، العدد 6مجلة الخوارزمي الھندسیة المجلد ليعمنى فائق 106 !!! !!!!! !!!!! !¾!! !œ!ñ!!!! ! !œ!! !œ!!œƒ! !œ!! !!! ! !œ!!œ!!ƒ!ƒ!! !œ!!! ! !!!œ!! œƒ! !! !!!!!! !¾ƒ!! !!œ!!! ! !!! !! !œ!! ! !! œš! ! ! !œ!¾! !!!!!î ð!!•!!!!î ò!!•!!!!î õ!!!! )2010( 112 101، صفحة 1، العدد 6مجلة الخوارزمي الھندسیة المجلد ليعمنى فائق 107 !!! !!!!! !!!!! !¾!! !œ!ò!!!!!! !¾ƒ!! !!œ!!! ! !!! !! !œ!! ! !! œš! ! ! !œ!¾! ! !! ! !œ!! !œ!!œƒ! !œ!! !!! ! !œ!!œ!!ƒ!ƒ!! !œ!!! ! !!!œ!! œƒ! !! !!!!!ï!!•!!!!ó!!•!!!!î í!!! )2010( 112 101، صفحة 1، العدد 6مجلة الخوارزمي الھندسیة المجلد ليعمنى فائق 108 !!! !!!!! !!!!! !¾!! !œ!ó!!!!!! !¾ƒ!! !!œ!!! ! !!! !! !œ!! ! !! œš! ! ! !œ!¾! ! !! ! !œ!! !œ!!œƒ! !œ!! !!! ! !œ!!œ!!ƒ!ƒ!! !œ!!! ! !!!œ!! œƒ! !! !!!!!ð!!•!!!!ò!!•!!!!ö!!! )2010( 112 101، صفحة 1، العدد 6مجلة الخوارزمي الھندسیة المجلد ليعمنى فائق 109 معدل الترشیح ٣-٣ فة استخدمت في الدراسة الحالیة ثالثة معدالت ترشیح مختل ) ٢، ١.٥، ١(ساعة أي ما یعادل /متر) ٩.٦، ٧.٣، ٤.٩(وھي .مرة بقدر المعدل السائد في محطات تصفیة الماء ان استخدام مثل ھذه المعدالت بشرط االبقاء على كفاءة الترشیح نفسھا من حیث نوعیة المیاه المنتجة، یؤدي الى زیادة ستقبل عدم الحاجة كمیة المیاه المنتجة مما قد یترتب علیھ في الم لبناء محطات تصفیة جدیدة، او حتى التوسع في المحطات الحالیة لسد حاجات المستھلك من المیاه، نتیجة لزیادة الكثافة السكانیة وھذا امر مھم جدًا من الناحیة الھندسیة لما یوفره من . المتوقعة .مردود اقتصادي ھام ویات تأثیر تغیر معدل الترشیح على إزالة مست ٤-٣ كورة الطبیعیة االولیة المختلفةالع ان ازالة المستویات المختلفة من ) ١(یتضح من الجدول العكورة الطبیعیة االولیة كانت متأثرة بمعدل الترشیح اذ یالحظ ان متوسط مستوى العكورة االولیة ) ١٣(في دورة التشغیل رقم ٠.٤٧وحدة بحیث كان متوسط مستوى العكورة الناتجة ٣.٦ ) ٢(وحدة بالنسب للمرشح ٠.٤٧و) ١(وحدة بالنسبة للمرشح ) ٤(وحدة للمرشح ٠.٥٩و) ٣(وحدة بالنسبة للمرشح ٠.٥٣و ساعة ، بینما یالحظ في /م٤.٩وذلك عند استخدام معدل ترشیح ان متوسط مستوى العكورة الناتجة كان ) ١٥(دورة التشغیل رقم دة بالنسبة للمرشح وح ٠.٥٠و) ١(وحدة بالنسبة للمرشح ٠.٤٨ بالنسبة للمرشح ٠.٦٢و) ٣(وحدة بالنسبة للمرشح ٠,٥٥و) ٢( ساعة وبمتوسط /م٧.٣أي عند زیادة معدل الترشیح الى ) ٤( وعند االستمرار بزیادة معدل . وحدة ٣.٥مستوى عكورة اولیة ساعة كان متوسط مستوى العكورة الناتجة /م٩.٨الترشیح الى وحدة بالنسبة للمرشح ٠.٥٢و) ١(رشح وحدة بالنسبة للم ٠.٥١ وحدة بالنسبة ٠.٦٨و) ٣(وحدة بالنسبة للمرشح ٠.٥٥و) ٢( كما یبدو ذلك من الجدول عند دورة التشغیل رقم ) ٤(للمرشح وھذا یدل على . وحدة ٣.٦وبمتوسط مستوى عكورة اولیة ) ١٧( زیادة متوسط مستوى العكورة للمیاه المعالجة بزیادة معدل ح، ولكن بشكل قلیل بالنسبة للمرشحات الثنائیة وبشكل الترشی .اوضح في المرشح االحادي ) ٣(وھذا السلوك للمرشحات یتبین بشكل اوضح في الجدول % ١٠٠ساعة ھي /م ٤.٩عند افتراض كفاءة الترشیح عند معدل ولمتوسط مستویات العكورة االولیة المختلفة، حیث یتبین ان كفاءة ت بشكل طفیف مع زیادة معدل الترشیح بالنسبة الترشیح قد انخفض للمرشحات الثنائیة ولكن االنخفاض في الكفاءة تظھر بشكل اوضح نسبیا في المرشح االحادي خصوصا عند زیادة معدل الترشیح الى .ساعة/ م ٩.٨ !¾! !! !œ•!! ! ! !!œ!¾!!! !! ƒ!!!!! ƒ!! ! œ!!ƒ!ƒ!! !œ!!! ! !! !œ!! œƒ! !! ! !! !œ! ! !! œš! ! ! !œ!!! œž!šƒ!! !!! متوسط مستوى العكورة )وحدة عكورة(االولیة %كفاءة المرشحات ساعة/معدل الترشیح م + الرمل النینفایت الكاربون + الرمل المنشط فحم + الرمل االنثراسیت الرمل ١٠٠ ١٠٠ ١٠٠ ١٠٠ ٤.٩ ٣.٦ ٩٣.٦٥ ٩٤.٤٤ ٩٢.١٦ ٩٥.٩٢ ٧.٣ ٨٦.٧٧ ٩٢.٨٦ ٩٠.٣٩ ٩٢.١٦ ٩.٨ ١٠٠ ١٠٠ ١٠٠ ١٠٠ ٤.٩ ٥.٦ ٩٥.٧٩ ٩٧.٦٢ ٩٧.٤٠ ٩٧.٣ ٧.٣ ٩١.٩٢ ٩٦.٤٧ ٩٧.٤٠ ٩٦.٠٥ ٩.٨ ١٠٠ ١٠٠ ١٠٠ ١٠٠ ٤.٩ ٩.٩ ٩٤.٩٣ ٩٧.٩٠ ٩٧.٧٥ ٩٨.٨٥ ٧.٣ ٨٨.٠٠ ٩٥.٨٨ ٩٢.٥٥ ٩٢.٤٧ ٩.٨ .ان القیم في الجدول ھي معدل دورتي تشغیل لكل مرشح(*) )2010( 112 101، صفحة 1، العدد 6مجلة الخوارزمي الھندسیة المجلد ليعمنى فائق 110 !!! !!!!! !!!!! !¾!! !œ!ô!!!!!!! º !!œ! !! œšº ! ! ! !œ!! !œ!! !! œ!!œ!!ƒ!! ! œ!!ƒ!ƒ!! !œ!!! ! !!!œ!! œƒ! !! ! !! ! ! !! !! ! !! œ!!! ! !!! !œ!!œƒ! !œ!!ƒ! ! !!! !! !šƒ! ! !!œ!¾!!! !!!œƒ! !! ƒ!!! !! ! œ! !!!!!ð!ó!!•!!! ! ! ! !!!š!!!!!ò!õ!!•!!! ! !! !!!š!!!!!ö!ö!!!! ! !! !!!š!!!! )2010( 112 101، صفحة 1، العدد 6مجلة الخوارزمي الھندسیة المجلد ليعمنى فائق 111 ) ٧.٣(الى ٤.٩شیح من وبمعنى اخر فان زیادة معدل التر ساعة لم تؤثر على نوعیة المیاه المعالجة بصورة واضحة /م ولكن عند زیادة معدل الترشیح الى . بالنسبة للمرشحات جمیعھا ، ) ١(ساعة یالحظ تأثر قلیل بالنسبة للمرشحات الثنائیة /م٩.٨ ولكن ھذا التأثر اوضح بالنسبة للمرشح االحادي ) ٣(، ) ٢( ردت نوعیة المیاه المعالجة نسبیا مقارنة ببقیة حیث ت) الرمل( ویمكن متابعة ھذا التغیر بشكل اكثر دقة في الشكل . المرشحات بالنسبة للمرشحات جمیعھا حیث یالحظ ان میل تردي النوعیة ) ٧( مقارنة ) الرملي(المنتجة كان اكثر في المرشح االحادي مكن استخدام وھذا االمر لھ اھمیتھ اذ ی. بالمرشحات الثنائیة معدالت ترشیح اعلى مما ھو مستخدم حالیا في محطات التصفیة .العاملة داخل القطر وبدون تأثر واضح لنوعیة المیاه المنتجة االستنتاجات.٤ في ضوء البیانات المستحصلة من التجارب العملیة :للمرشحات االربعة یمكن ادراج االستنتاجات االتیة نتائج جیدة من حیث قابلیتھ ) ایتالنینف+الرمل(حقق مرشح ١ على ازالة مستویات العكورة المختلفة، ویلیھ بعد ذلك او ) الكاربون المنشط+الرمل(یوازیھ احیانًا في الكفاءة مرشح % ٩١.٣١ازالة في العكورة مقدارھا ) ١(فمثال حقق المرشح ساعة ، /م٤.٩وحدة معدل ترشیح ٩.٩عند مستوى عكورة في المرشح % ٩١.٢١ق ازالة مقدارھا في حین امكن تحقی .عند الظروف نفسھا) ٢( امكانیة استخدام معدالت ترشیح اعلى مما ھو مستخدم حالیًا ٢ ، ولحد ) المرشحات االحادیة(في محطات التصفیة داخل ویمكن استخدام معدالت ترشیح . ساعة/متر٧.٣معدل ترشیح ات ساعة في حالة تغییر المرشح/متر ٩.٨اعلى تصل الى الحالیة الى مرشحات ثنائیة، ھذه المعدالت تتجاوز المعدالت -١(السائدة حالیًا في محطات تصفیة المیاه بمدى یتراوح من مرة على اقل االحتماالت مما ینعكس على زیادة كمیات ) ٢ .المیاه المنتجة المصادر.٥ [1]al-ani, f.h., (1998). "an investigation into the use of locally produced granular activated carbon in treatment of water supplies", ph.d. thesis, university of technology. [2]al-naqib, s.q. and al-dabbagh t.h. (1993). "some physical and geotechnical properties of the new rock type (ninivite)", proc. of the 26th annual u.k./9-13 sep. 1990. [3]al-rawi, s.m. (1987). "turbidity removal of drinking water by dual media filtration", m.sc. thesis, university of mosul. [4]amirtharajah, a., (1988). "some theoretical and conceptual views of filtration", j. awwa, 80:12. [5]aswad, k.j.; amin m.a. and al-naqib, s.q. (1995). "marl-112s interaction under sufacial oxidizing conditions" dirasat, 22b:6. [6]casey, t.j. (1997). "unit treatment processes in water and waste water engineering" john wiley and sons. [7] jassim, s.z. and al-naqib, s.q(1989) "ninivite: a new form of porcelainite and the associated alunite and jarosite minerals. a suite relatcd to sulphuric acid seepages south of mosul, northern ira. jounal of geological soc. of iraq,22,1. [8]metcalf and eddy, inc. (1991). "wastewater engineering: treatment, disposal and reuse", 3rd ed ., mc-graw hill, inc., new york, usa. [9]schulz, c.r and okun, d.a. (1984). "surface water treatment for communities in developing countries", john wiley and sons, inc. usa. [10] steel, e.w. and mcghee, t.j. (1985). "water supply and sewage", 5th edition. mcgraw hill co., new york. [11] tchobanoglous, g.and schroeder, e.d. (1985). "water quality: characteristics modeling and modification", addison wesley publishing co. [12] thomas, w. j. and crittenden, b. (1998). "adsorption technology and design", reed educational and professional publishing ltd. [13] روان ة، م ة ). "١٩٩٩(آل جندول ات المعدنی التشخیص وین یة لتك ة الحامض تحلالت الكبریتاتی ة لل والجیوكیمیائی ل (الفتحة ة الموص وب مدین ط جن ین االوس مال / المایوس ش .، رسالة ماجستیر، كلیة العلوم، جامعة الموصل)"العراق [14] ات ) "١٩٩٣(محمد، ابراھیم قاسم خریة وبیئ ة وص معدنی راق، رب الع ي غ یة ف ة والسیلس خور الطینی یب الص ترس الة داد رس ة بغ وم، جامع ة العل وراه، كلی دكت muna faiq ali al-khwarizmi engineering journal, vol. 6, no. 1, pp 101 -112 (2010) 112 the study of ability of local ninivite rocks in purification of drinking water muna faiq ali department of environmental engineering/ college of engineering/ university of baghdad abstract this study is conducted to verify the efficienecy of local ninivite rock when used in the treatment of drinking water in plants operating currently in the country in order to develop the situation of these stations to cope with the increase in population. also, this will limit the pollutian which are increasing in the country's rivers. (euphrates and tigris). these rivers are the sources to feed all water treatment plants in the country. the idea is the develop or the modify these stations by replacing part of top layer of sand filters used in these stations with ninivite rock to operate as filters composed of two medium. the efficiency of this rock is compared with other materials used successfully worldwide in this area, such as activated carbon and anther cite. the comparison is made on the basis of percentage of the removal of turbidity levels, and on the possibility using high filtration rates that exceed the rates currently used in the treatment plants inside the country. a pilot plant in the laboratory scale was built to simulate the treatment plants within the country. it contains all the operating units of traditional basins. these basins are coagulation, floculation, sedimentation and filtration tanks. filtration unit, in the present study, is formed of the four glass columns (filters), which worked in parallel and on same time. the 20 cm of ninivite rock activated carbon, anthercite is placed in first, second, third column respectively, the layer is placed above 40 cm of sand layer, and consequently it worked a filter with two mediums. the fourth column contained only sand for a depth of 60 cm to work as filter with single medium. the same size grains of material used in the present study (0.82 mm) and uniformity coefficient which is equal to 106. دراسة امكانية استخدام صخور النينفايت المحلية في تصفية مياه الشرب منى فائق علي مجلة الخوارزمي الهندسية المجلد 6، العدد 1، صفحة 101 112 (2010) al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 6, no. 1, pp 101-112 (2010) دراسة إمكانية استخدام صخور النينفايت المحلية في تصفية مياه الشرب منى فائق علي قسم هندسة البيئة / كلية الهندسة / جامعة بغداد (received 9 november 2008; accepted 6 december 2009) الخلاصة : للتحقق من كفاءة صخرة النينفايت المحلية عند استخدامها كوسط ترشيح في تصفية مياه الشرب للمحطات العاملة داخل القطر حاليا للاستعانة بها في تطوير واقع حال هذه المحطات وجعلها تواكب الزيادة الحاصلة في الكثافة السكانية كذلك مواجهة زيادة التلوث بالملوثات العضوية التي تعانيها الانهار في القطر (دجلة والفرات) والتي تعد المصادر الوحيدة لتغذية كافة محطات التصفية بالماء في القطر. ان فكرة التطوير او التحوير هذه تتم باستبدال جزء من الطبقة العليا لمرشحات الرمل المستخدمة في تلك المحطات بصخرة النينفايت لتعمل بذلك كمرشحات ثنائية الوسط. وبغية التحقق من كفاءة الصخرة فقد تمت مقارنتها مع مواد اخرى تستخدم بنجاح عالمياً في هذا المجال، وهي الكاربون المنشط وفحم الانثراسيت. وتمت المقارنة على اساس قابلية ازالة مستويات العكورة المختلفة، وامكانية استخدام معدلات ترشيح عالية تفوق معدلاتها المستخدمة حالياً في محطات التصفية داخل القطر. دعت الحاجة في اجراء تجارب هذا القسم الى بناء محطة بحثية بمقياس مختبري مشابهة لمحطات التصفية العاملة داخل القطر. وتحتوي على كافة الوحدات التقليدية العاملة من احواض تخثير وتلبيد وترسيب اضافة الى منظومة الترشيح. تكونت منظومة الترشيح في الدراسة الحالية من اربعة اعمدة زجاجية (مرشحات) تعمل بشكل متوازٍ وفي ان واحد بحيث احتوى العمود الاول والثاني والثالث على 20 سم من صخرة النينفايت والكاربون المنشط وفحم الانثراسيت على التوالي وموضوعة فوق 40 سم من الرمل وبذا فهي تعمل كمرشحات ثنائية الوسط بينما احتوى المرشح الرابع على الرمل فقط وبعمق 60 سم ليعمل بذلك كمرشح احادي الوسط. ولغرض الحصول على المقارنة المطلوبة فقد تم استخدام الحجم المؤثر نفسه لحبيبات المواد المستخدمة في الدراسة (0.82 ملم) وكذلك معامل الانتظام الذي بلغ 106. الكلمات المفتاحية: النينفايت – المرشحات الأحادية والثنائية، محطات الإسالة ، الانثراسيت ، الكاربون، المنشط. 1. المقدمة تم اكتشاف هذه الصخرة من قبل النقيب(2) عام 1987 خلال قيامه باعداد خارطة جيولوجية مفصلة لمنطقة جنوب محافظة نينوى. وفي بادئ الامر ساد الاعتقاد بانها احد الانواع الجديدة من صخرة البورسيلينايت المحلية (وهي صخرة موجودة في الصحراء الغربية ومنطقة الجزيرة غرب وجنوب العراق)]14[. ولكن بعد دراستها وتحليلها ومعرفة خواصها تم عدها صخرة رسوبية محلية يتم اكتشافها لاول مرة، وقد تمت تسميتها من قبل (جاسم والنقيب)[7,2] باسم صخرة النينفايت (ninivite)[7, 2]. يوضح الشكل (1) التركيبة التي تتكون منها صخرة النينفايت، اذ انه يمثل شكلاً شبه بيضوي تتمركز السليكا في وسطه، وتكون محاطة بانطقة يتركز فيها معدن الالونايت kal2(so4)2 (oh)6 ومعدن الجاروسايت kfe3(so4)2 (oh)6 فضلا عن المعادن الحديدية وعلى التوالي باتجاه خارج الشكل. ان هذا الارتباط بين المعدنين والصخرة تكون نتيجة لعمليات تحلل ثانوية لصخور المارل marl والصخور الاخرى المرافقة لها والتي تعزى الى تفاعل حامض الكبريتيك (التحللات الكبريتيدية الحامضية) تحت الظروف الاعتيادية من ضغط وحرارة (p-t)[5]. ان التفاعلات تحت سطح الارض تكون مصدرا لغاز كبريتيد الهيدروجين h2s والذي يتأكسد بعدئذ الى حامض الكبريتيك فوق مستوى المياه الجوفية بفعل نوع خاص من البكتريا المسماة (thio basillus thio oxidans ). ان التحللات الكبريتيدية الحامضية تؤثر في المعادن الطينية والكاربونات لصخور المارل تحت ظروف واطئة من الدالة الحامضية (4.5-1.5)ph مما يؤدي الى حركة معظم العناصر وترسبها في الانطقة الخارجية وبقاء السليكا والتيتانيوم في الوسط. الشكل (1) تركيبة صخرة النينفايت [5] . ولكون الدورة الطبيعية لانبعاث غاز كبريتيد الهيدروجين وتأكسده الى حامض الكبريتيك وتأثيره في المعادن الطينية مستمرة، فان البحوث جارية لاكتشاف مناطق جديدة تحوي ترسبات صخرة النينفايت. 2. المواد وطرائق العمل بغية تحقيق الأهداف المنشودة من هذه الدراسة ومنها محاكاة الواقع، فقد تم بناء محطة بحثية بمقياس مختبري (laboratory scale pilot plant) تعمل باسلوب الجاذبية (على أساس ان جميع محطات تصفية الماء داخل القطر تعمل باسلوب الجاذبية) وقد زودت بوحدات المعاملة التقليدية نفسها والموجودة في محطات تصفية المياه كافة. ويوضح الشكل (2) وحدات المحطة البحثية. 2-1 اجزاء وحدات المحطة البحثية: ان وحدات المحطة البحثية تم تصميمها اعتمادا على المعادلات والمحددات والمعايير التصميمية الموصوفة في المصادر المتوفرة [11, 10, 9, 8, 6]. أ خزان الماء الخام الارضي: تم استخدام ثلاثة خزانات كل منها بابعاد (1م×1م×1م) لغرض خزن الماء الخام الذي كان ينقل مباشرة من نهر دجلة بوساطة عجلة حوضية. وضعت هذه الخزانات على ارتفاع 20سم من سطح الارض وجرى ربطها مباشرة بمضخة ماء لنقل الماء من كل خزان عند اجراء اية دورة تشغيل الى خزان الماء الخام المجهز للمحطة. ب خزان الماء الخام المجهز للمحطة البحثية: ان الخزان مصنوع من مادة بلاستيكية وبسعة 120 لتر ووضع على ارتفاع 230 سم من سطح الارض لغرض تجهيز الماء الخام الى حوض التخثير (حوض المزج السريع) بوساطة الجاذبية. جرى تزويد الخزان بطواف ماء للحفاظ على ارتفاع ثابت للماء فيه. ويتم التخلص من التصريف الزائد (over flow) عن طريق صمام (valve) متصل بالخزان من مستوى الطواف ، يقوم بارجاع الماء الفائض الى الخزان الارضي للماء الخام. جـ حوض التخثير (حوض المزج السريع): تم تصنيع هذا الحوض من الزجاج وبابعاد (10.5 سم× 10.5سم ×10.5سم) وبفترة مكوث هيدروليكية مقدارها دقيقة واحدة. الغرض الرئيس من استخدام هذا الحوض هو اضافة المادة المخثرة الكيمياوية (كبريتات الالمنيوم ) بوساطة سحاحة مجهزة لهذا الغرض وذلك لجعل المواد المسببة للعكورة (المواد الرملية العالقة والغروية) غير مستقرة ومشتتة. ويتم تجهيز هذا الحوض بالماء الخام مباشرة من خزان الماء الخام المجهز للمحطة. يكون هذا الحوض مزود بآلة مزج سريع تتكون من محراك (stirrer) متصل بستة مجاذيف (paddles) وتدور بسرعة 200 دورة في الدقيقة، يمكن السيطرة على سرعة الالة المازجة بوساطة منظم سرعة (regulator) يستخدم لهذا الغرض. د حوض التلبيد (حوض المزج البطئ): تم تصنيع هذا الحوض من الزجاج وبابعاد (50سم×30سم×22سم) وبفترة مكوث هيدروليكية مقدارها 30دقيقة . والغرض الرئيسي من استخدام هذا الحوض هو اعطاء فرصة للمواد المسببة للعكورة غير المستقرة والمشتتة والتي تكونت في حوض التخثير ان تتلبد وتتراكم مع بعضها لتكوين مواد اكبر واثقل ، وعليه فان الماء كان ينتقل مباشرة (بفعل الجاذبية) من حوض التخثير الى حوض التلبيد. يكون حوض التلبيد مجهزا بآلتي مزج بطيء وعلى التوالي وتتكون كل واحدة منهما من محراك متصل باربعة مجاذيف، تدور الاولى بسرعة 60 دورة/ دقيقة وتدور الثانية بسرعة 40 دورة/ دقيقة ، وتتم السيطرة على سرعتيها بوساطة منظمي سرعة (regulators) وحوض التلبيد هذا مرتبط بحوضي ترسيب وبشكل مباشر. هـ حوضا الترسيب: تم تصنيع كل حوض من الزجاج وبابعاد (54سم×34سم×28سم) وبفترة مكوث هيدروليكية مقدارها 120دقيقة. والغرض الرئيس من استخدام هذين الحوضين هو ترسيب المواد المتلبدة والمتكونة في حوض التلبيد وعليه فان الماء كان ينتقل من حوض التلبيد الى حوض الترسيب مباشرة. ان كل حوض ترسيب مزود بحاجز (baffle) في مقدمته لتوزيع الجريان بانتظام على المقطع العرضي الداخلي للحوض. وكل حوض مزود في نهايته بثلاثة صمامات، اثنين يستخدمان لتسليط الماء على اعمدة الترشيح ويستخدم الثالث لاخذ النماذج والتخلص من التصريف الزائد (over flow) عند تشغيل المحطة البحثية بتصريف اقل مما هو مصمم عليه. و أعمدة الترشيح: تم استخدام اربعة اعمدة ترشيح مصممة لتعمل بشكل متواز وفي آن واحد، ويوضح الشكل (3) الابعاد التصميمية لهذه الاعمدة. يتالف كل عمود من انبوب اسطواني بقطر 53 ملم وارتفاع 950 ملم مصنوع من الزجاج ومزود في اسفله بصمام لتصريف الماء المعالج وتنظيم الجريان ولاجراء عملية الغسل لمادة وسط الترشيح عند انتهاء أي دورة تشغيل. ان الماء الخارج من كل صمام في حوض الترسيب يسلط على عمود الترشيح من الاعلى، وعلى بعد 5 سم من النهاية العليا للعمود يوجد صمام لتصريف الماء خلال عملية الغسل. تم تزويد كل عمود بصمامات على اعماق 30 سم، 50 سم 70سم ، 90 سم من النهاية العليا للعمود. وتم ربطها ببيزومترات مثبتة على لوحة خشبية لقياس مستوى الماء على ارتفاعات مختلفة في العمود لتحديد فقدان الشحنة خلال دورة التشغيل. وقد تم اختيار مادة وسط الترشيح داخل العمود الواحد بارتفاع 60 سم وذلك لكفاءة هذا العمق في المرشحات الثنائية والأحادية. · العمود الاول: يتكون من (20) سم من صخرة النينفايت فوق (40) سم من مادة الرمل. · العمود الثاني: يتكون من (20) سم من الكاربون المنشط فوق (40) سم من مادة الرمل. · العمود الثالث: يتكون من (20) سم من فحم الانثراسيت فوق (40) سم من مادة الرمل. · العمود الرابع: يتكون من (60) سم من مادة الرمل. الشكل (3) الإبعاد التصميمية لأعمدة الترشيح المستخدمة. ز لوحة المانوميتر وهي لوحة خشبية بابعاد (240سم×120سم) مثبتة على الجدار الى الخلف من المرشحات وتحتوي على 16 انبوبا زجاجيا (بيزومترات) وذلك لقياس ضغط الماء في العمود (المرشح) ، لتحديد فقدان الشحنة خلال دورة التشغيل. 3. النتائج والمناقشة 3-1 إزالة مستويات العكورة تم في هذه الدراسة تشغيل المحطة البحثية بمستويات عكورة طبيعية، وجرى تحديد جرعة الشب الواجب اضافتها بوساطة فحص الجرة الى حوض التخثير (حوض المزج السريع) لكل دورة تشغيل لتقليل مستويات العكورة، وتثبيت مستواها تقريبا قبل تسليط المياه الخارجة من حوضي الترسيب الى المرشحات الاربعة في آن واحد، لتعمل بشكل متواز. ومن ثم دراسة ازالة مستويات العكورة المختلفة في كل مرشح. 3-2 ازالة مستويات العكورة الطبيعية يلخص الجدول (1) متوسط مستويات العكورة الاولية الداخلة الى كل مرشح، ومتوسط مستوياتها الناتجة في المياه المعالجة في تلك المرشحات عند نهاية دورة التشغيل لمرشح الرمل ولمعدلات الترشيح المختلفة المستخدمة في الدراسة. حيث يلاحظ في دورة التشغيل رقم(1) ان متوسط مستوى العكورة الطبيعية الاولية في اعلى مستوى لها 9.9 وحدة، بحيث كانت المياه المعالجة ذات متوسط مستوى عكورة 0.86 وحدة بالنسبة للمرشح (1) و 0.87 وحدة بالنسبة للمرشح (2) و0.93 وحدة بالنسبة للمرشح (3) و1.11 وحدة بالنسبة للمرشح (4) أي بكفاءة ازالة ((%88.8 , %90.6 , %91.2 ,%91.3. بينما يلاحظ في دورة التشغيل رقم (16) ان متوسط مستوى العكورة الاولية كانت في اقل مستوى لها 3.2 وحدة بحيث كانت المياه المعالجة ذات متوسط مستوى عكورة 0.49 وحدة بالنسبة للمرشح (1) و0.51 وحدة بالنسبة للمرشح (2) و0.55 وحدة بالنسبة للمرشح (3) و0.63 وحدة بالنسبة للمرشح (4) أي بكفاءة ازالة ((%80.36 ,%82.86 , %84.16, %84.7 لكل مرشح على التوالي. ويتضح من البيانات المستحصلة من هذا الجدول ان قيم مستويات العكورة الناتجة في المياه المعالجة لم تتجاوز (1) وحدة عكورة في المرشحات (1),(2),(3) ولجميع دورات التشغيل. في حين ظهر بعض التجاوز الطفيف عن القيمة المذكورة في المرشح (4). وهذا يؤكد الحقائق التي سبق ذكرها عن مساوئ هذا المرشح الرملي الاحادي مقارن باداء المرشحات ثنائية الوسط. وعموماً فان متوسط مستويات العكورة الناتجة للمياه المعالجة تحت الظروف المختلفة من مستويات العكورة الاولية واختلاف معدلات الترشيح، لم تتجاوز مواصفات منظمة الصحة العالمية والمواصفات الوطنية العراقية والبالغة 5 وحدة او اقل، وهذا يدل على ان المرشحات قد انتجت مياه بنوعية جيدة ومرغوب فيها. ويتبين من الجدول (2) بان المرشحات جميعها قد حققت كفاءة ازالة عالية ولمستويات العكورة الطبيعية الاولية المختلفة حيث لم تقل كفاءة الازالة للمرشح (1) عن 84.69% ، والمرشح (2) عن 84.06% والمرشح (3) عن 82.81% والمرشح (4) عن 80.31% ولجميع دورات التشغيل التي تم اجراؤها. ويتبين بشكل واضح ان مرشح (الرمل+النينفايت) كان الاكفأ مقارنة بمرشحات (الرمل + فحم الانثراسيت، الرمل) في ازالة مستويات العكورة الاولية ولمستوياتها الطبيعية المختلفة مع التقارب الواضح في كفاءة ازالة مرشح (الرمل+ الكاربون المنشط) من مرشح (الرمل + النينفايت). تبين الاشكال من (4) الى ( 6 ) تغاير مستويات العكورة الناتجة في المياه المعالجة من المرشحات مع الوقت لبعض دورات التشغيل علماً ان عملية التشغيل هي الفترة بين عملية غسل واخرى . الجدول ، متوسط مستوى العكورة الطبيعية الناتجة من المياه المعالجة للمرشحات دورة التشغيل معدل الترشيح م/ساعة العكورة الاولية (وحدة عكورة) متوسط مستوى العكورة الطبيعية الناتجة من المرشحات (وحدة) الرمل + صخرة النينفايت الرمل+ الكاربون المنشط الرمل+ فحم الانثراسيت الرمل 1 4.9 9.9 0.86 0.87 0.93 1.11 2 5.8 0.75 0.76 0.82 0.91 3 9.8 0.86 0.88 0.93 1.10 4 5.6 0.73 0.75 0.83 0.91 13 3.6 0.47 0.47 0.53 0.59 14 3.3 0.46 0.46 0.52 0.60 5 7.3 9.8 0.87 0.89 0.94 1.13 6 5.6 0.74 0.76 0.84 0.94 7 9.8 0.87 0.88 0.95 1.14 8 5.5 0.75 0.77 0.83 0.95 15 3.5 0.48 0.50 0.55 0.62 16 3.2 0.49 0.51 0.55 0.63 9 9.8 9.9 0.92 0.94 0.97 1.25 10 5.7 0.76 0.77 0.85 0.98 11 9.8 0.93 0.94 0.97 1.24 12 5.5 0.76 0.77 0.85 0.99 17 3.6 0.51 0.52 0.55 0.68 18 3.5 0.50 0.52 0.56 0.66 الجدول ، كفاءة ازالة مستويات العكورة الطبيعية المختلفة للمرشحات دورة التشغيل معدل الترشيح م/ساعة العكورة الاولية (وحدة عكورة) كفاءة ازالة العكورة الطبيعية الناتجة من المرشحات(%) الرمل + النينفايت الرمل+ الكاربون المنشط الرمل+ فحم الانثراسيت الرمل 1 4.9 9.9 91.31 91.21 90.61 88.79 2 5.8 87.07 86.90 85.86 84.31 3 9.8 91.22 91.02 90.51 88.78 4 5.6 86.96 86.61 85.18 83.75 13 3.6 86.94 86.94 85.28 83.61 14 3.3 86.06 86.06 84.24 81.82 5 7.3 9.8 91.12 90.92 90.41 88.47 6 5.6 86.79 86.43 85.00 83.21 7 9.8 91.12 91.02 90.31 88.37 8 5.5 86.36 86.00 84.91 82.73 15 3.5 86.29 85.71 84.29 82.29 16 3.2 84.69 84.06 82.81 80.31 9 9.8 9.9 90.71 90.51 90.20 87.37 10 5.7 86.67 86.49 85.09 82.81 11 9.8 90.51 90.41 90.10 87.35 12 5.5 86.18 86.00 84.55 82.00 17 3.6 85.83 85.56 84.72 81.11 18 3.5 85.71 85.14 84.0 81.14 (أ) (ب) (ج) الشكل (4) مستويات العكورة الطبيعية الناتجة في المياه المعالجة خلال المرشحات مع الوقت دورة التشغيل رقم (أ) 13 ، (ب) 15 ، (ج) 18 . (أ) (ب) (ج) الشكل (5) مستويات العكورة الطبيعية الناتجة في المياه المعالجة خلال المرشحات مع الوقت دورة التشغيل رقم (أ) 2 ، (ب) 6 ، (ج) 10. (أ) (ب) (ج) الشكل (6) مستويات العكورة الطبيعية الناتجة في المياه المعالجة خلال المرشحات مع الوقت دورة التشغيل رقم (أ) 3 ، (ب) 5 ، (ج) 9. 3-3 معدل الترشيح استخدمت في الدراسة الحالية ثلاثة معدلات ترشيح مختلفة وهي (4.9، 7.3، 9.6) متر/ساعة أي ما يعادل (1، 1.5 ، 2) مرة بقدر المعدل السائد في محطات تصفية الماء. ان استخدام مثل هذه المعدلات بشرط الابقاء على كفاءة الترشيح نفسها من حيث نوعية المياه المنتجة، يؤدي الى زيادة كمية المياه المنتجة مما قد يترتب عليه في المستقبل عدم الحاجة لبناء محطات تصفية جديدة، او حتى التوسع في المحطات الحالية لسد حاجات المستهلك من المياه، نتيجة لزيادة الكثافة السكانية المتوقعة. وهذا امر مهم جداً من الناحية الهندسية لما يوفره من مردود اقتصادي هام. 3-4 تأثير تغير معدل الترشيح على إزالة مستويات العكورة الطبيعية الاولية المختلفة يتضح من الجدول (1) ان ازالة المستويات المختلفة من العكورة الطبيعية الاولية كانت متأثرة بمعدل الترشيح اذ يلاحظ في دورة التشغيل رقم (13) ان متوسط مستوى العكورة الاولية 3.6 وحدة بحيث كان متوسط مستوى العكورة الناتجة 0.47 وحدة بالنسبة للمرشح (1) و0.47 وحدة بالنسب للمرشح (2) و0.53 وحدة بالنسبة للمرشح (3) و0.59 وحدة للمرشح (4) وذلك عند استخدام معدل ترشيح 4.9م/ساعة ، بينما يلاحظ في دورة التشغيل رقم (15) ان متوسط مستوى العكورة الناتجة كان 0.48 وحدة بالنسبة للمرشح (1) و0.50 وحدة بالنسبة للمرشح (2) و0,55 وحدة بالنسبة للمرشح (3) و0.62 بالنسبة للمرشح (4) أي عند زيادة معدل الترشيح الى 7.3م/ساعة وبمتوسط مستوى عكورة اولية 3.5 وحدة. وعند الاستمرار بزيادة معدل الترشيح الى 9.8م/ساعة كان متوسط مستوى العكورة الناتجة 0.51 وحدة بالنسبة للمرشح (1) و0.52 وحدة بالنسبة للمرشح (2) و0.55 وحدة بالنسبة للمرشح (3) و0.68 وحدة بالنسبة للمرشح (4) كما يبدو ذلك من الجدول عند دورة التشغيل رقم (17) وبمتوسط مستوى عكورة اولية 3.6 وحدة. وهذا يدل على زيادة متوسط مستوى العكورة للمياه المعالجة بزيادة معدل الترشيح، ولكن بشكل قليل بالنسبة للمرشحات الثنائية وبشكل اوضح في المرشح الاحادي. وهذا السلوك للمرشحات يتبين بشكل اوضح في الجدول (3) عند افتراض كفاءة الترشيح عند معدل 4.9 م/ساعة هي 100% ولمتوسط مستويات العكورة الاولية المختلفة، حيث يتبين ان كفاءة الترشيح قد انخفضت بشكل طفيف مع زيادة معدل الترشيح بالنسبة للمرشحات الثنائية ولكن الانخفاض في الكفاءة تظهر بشكل اوضح نسبيا في المرشح الاحادي خصوصا عند زيادة معدل الترشيح الى 9.8 م/ ساعة. الجدول ، كفاءة المرشحات لازالة مستويات العكورة الطبيعية الاولية بتغير معدل الترشيح(*) متوسط مستوى العكورة الاولية (وحدة عكورة) معدل الترشيح م/ساعة كفاءة المرشحات % الرمل+ النينفايت الرمل + الكاربون المنشط الرمل + فحم الانثراسيت الرمل 3.6 4.9 100 100 100 100 7.3 95.92 92.16 94.44 93.65 9.8 92.16 90.39 92.86 86.77 5.6 4.9 100 100 100 100 7.3 97.3 97.40 97.62 95.79 9.8 96.05 97.40 96.47 91.92 9.9 4.9 100 100 100 100 7.3 98.85 97.75 97.90 94.93 9.8 92.47 92.55 95.88 88.00 (*) ان القيم في الجدول هي معدل دورتي تشغيل لكل مرشح. (أ) (ب) (ج) الشكل (7) تأثير زيادة معدل الترشيح على نوعية المياه المنتجة باختلاف متوسط مستويات العكورة الطبيعية الاولية الداخلة الى المرشحات والتي تساوي (أ) 3.6 وحدة عكورة ، (ب) 5.8 وحدة عكورة ، (ج) 9.9 وحدة عكورة . وبمعنى اخر فان زيادة معدل الترشيح من 4.9 الى (7.3) م/ساعة لم تؤثر على نوعية المياه المعالجة بصورة واضحة بالنسبة للمرشحات جميعها. ولكن عند زيادة معدل الترشيح الى 9.8م/ساعة يلاحظ تأثر قليل بالنسبة للمرشحات الثنائية (1) ، (2) ، (3) ولكن هذا التأثر اوضح بالنسبة للمرشح الاحادي (الرمل) حيث تردت نوعية المياه المعالجة نسبيا مقارنة ببقية المرشحات. ويمكن متابعة هذا التغير بشكل اكثر دقة في الشكل (7) بالنسبة للمرشحات جميعها حيث يلاحظ ان ميل تردي النوعية المنتجة كان اكثر في المرشح الاحادي (الرملي) مقارنة بالمرشحات الثنائية. وهذا الامر له اهميته اذ يمكن استخدام معدلات ترشيح اعلى مما هو مستخدم حاليا في محطات التصفية العاملة داخل القطر وبدون تأثر واضح لنوعية المياه المنتجة. 4. الاستنتاجات في ضوء البيانات المستحصلة من التجارب العملية للمرشحات الاربعة يمكن ادراج الاستنتاجات الاتية: 1حقق مرشح (الرمل+النينفايت) نتائج جيدة من حيث قابليته على ازالة مستويات العكورة المختلفة، ويليه بعد ذلك او يوازيه احياناً في الكفاءة مرشح (الرمل+الكاربون المنشط) فمثلا حقق المرشح (1) ازالة في العكورة مقدارها 91.31% عند مستوى عكورة 9.9 وحدة معدل ترشيح 4.9م/ساعة ، في حين امكن تحقيق ازالة مقدارها 91.21% في المرشح (2) عند الظروف نفسها. 2امكانية استخدام معدلات ترشيح اعلى مما هو مستخدم حالياً في محطات التصفية داخل (المرشحات الاحادية) ، ولحد معدل ترشيح 7.3متر/ساعة. ويمكن استخدام معدلات ترشيح اعلى تصل الى 9.8 متر/ساعة في حالة تغيير المرشحات الحالية الى مرشحات ثنائية، هذه المعدلات تتجاوز المعدلات السائدة حالياً في محطات تصفية المياه بمدى يتراوح من (1-2) مرة على اقل الاحتمالات مما ينعكس على زيادة كميات المياه المنتجة. 5. المصادر [1] al-ani, f.h., (1998). "an investigation into the use of locally produced granular activated carbon in treatment of water supplies", ph.d. thesis, university of technology. [2] al-naqib, s.q. and al-dabbagh t.h. (1993). "some physical and geotechnical properties of the new rock type (ninivite)", proc. of the 26th annual u.k./9-13 sep. 1990. [3] al-rawi, s.m. (1987). "turbidity removal of drinking water by dual media filtration", m.sc. thesis, university of mosul. [4] amirtharajah, a., (1988). "some theoretical and conceptual views of filtration", j. awwa, 80:12. [5] aswad, k.j.; amin m.a. and al-naqib, s.q. (1995). "marl-112s interaction under sufacial oxidizing conditions" dirasat, 22b:6. [6] casey, t.j. (1997). "unit treatment processes in water and waste water engineering" john wiley and sons. [7] jassim, s.z. and al-naqib, s.q(1989) "ninivite: a new form of porcelainite and the associated alunite and jarosite minerals. a suite relatcd to sulphuric acid seepages south of mosul, northern ira. jounal of geological soc. of iraq,22,1. [8] metcalf and eddy, inc. (1991). "wastewater engineering: treatment, disposal and reuse", 3rd ed ., mc-graw hill, inc., new york, usa. [9] schulz, c.r and okun, d.a. (1984). "surface water treatment for communities in developing countries", john wiley and sons, inc. usa. [10] steel, e.w. and mcghee, t.j. (1985). "water supply and sewage", 5th edition. mcgraw hill co., new york. [11] tchobanoglous, g.and schroeder, e.d. (1985). "water quality: characteristics modeling and modification", addison wesley publishing co. [12] thomas, w. j. and crittenden, b. (1998). "adsorption technology and design", reed educational and professional publishing ltd. [13] آل جندولة، مروان (1999). "التشخيصات المعدنية والجيوكيميائية للتحللات الكبريتاتية الحامضية لتكوين الفتحة (المايوسين الاوسط جنوب مدينة الموصل/ شمال العراق)"، رسالة ماجستير، كلية العلوم، جامعة الموصل. [14] محمد، ابراهيم قاسم (1993) "معدنية وصخرية وبيئات ترسيب الصخور الطينية والسيلسية في غرب العراق، رسالة دكتوراه، كلية العلوم، جامعة بغداد the study of ability of local ninivite rocks in purification of drinking water muna faiq ali department of environmental engineering/ college of engineering/ university of baghdad abstract this study is conducted to verify the efficienecy of local ninivite rock when used in the treatment of drinking water in plants operating currently in the country in order to develop the situation of these stations to cope with the increase in population. also, this will limit the pollutian which are increasing in the country's rivers. (euphrates and tigris). these rivers are the sources to feed all water treatment plants in the country. the idea is the develop or the modify these stations by replacing part of top layer of sand filters used in these stations with ninivite rock to operate as filters composed of two medium. the efficiency of this rock is compared with other materials used successfully worldwide in this area, such as activated carbon and anther cite. the comparison is made on the basis of percentage of the removal of turbidity levels, and on the possibility using high filtration rates that exceed the rates currently used in the treatment plants inside the country. a pilot plant in the laboratory scale was built to simulate the treatment plants within the country. it contains all the operating units of traditional basins. these basins are coagulation, floculation, sedimentation and filtration tanks. filtration unit, in the present study, is formed of the four glass columns (filters), which worked in parallel and on same time. the 20 cm of ninivite rock activated carbon, anthercite is placed in first, second, third column respectively, the layer is placed above 40 cm of sand layer, and consequently it worked a filter with two mediums. the fourth column contained only sand for a depth of 60 cm to work as filter with single medium. the same size grains of material used in the present study (0.82 mm) and uniformity coefficient which is equal to 106. � embed pbrush ��� 20 109 _1173207870 al-khwarizmi engineering!!! journal al-khwarizmi engineering journal, vol. 6, no. 1, pp 3147 (2010) bionics-based approach for object tracking to implement in robot applications hussam k. abdul-ameer department of biomedical engineering/ al-khwarizmi college of engineering/ university of baghdad (received 7 december 2009: accepted 17 february 2010) abstract in this paper, an approach for object tracking that is inspired from human oculomotor system is proposed and verified experimentally. the developed approach divided into two phases, fast tracking or saccadic phase and smooth pursuit phase. in the first phase, the field of the view is segmented into four regions that are analogue to retinal periphery in the oculomotor system. when the object of interest is entering these regions, the developed vision system responds by changing the values of the pan and tilt angles to allow the object lies in the fovea area and then the second phase will activate. a fuzzy logic method is implemented in the saccadic phase as an intelligent decision maker to select the values of the pan and tilt angle based on suggested logical rules. in smooth pursuit phase, the object is kept in the center area of the field of the view by smooth adjusting the values of the pan and tilt angles where this stage is analogue to putting the observing object in the fovea centralis of the oculomotor system. the proposed approach was implemented by using (camera-pan / tilt) configuration and showed good results to improve the vision capability of the humanoid robots. keywords: tracking, bionics, and fuzzy decision maker. 1. introduction human vision systems have an appropriate ability to interpret nature scenes in real time, despite the limited speed of the biological architecture available for such tasks. the cerebral control system that directs the eye toward an object for viewing is as significant as the system that interprets the visual signals received from the eye. in the same way as the cerebral control system, the most important role of the active vision system is to direct an artificial visual receptor, such as a ccd camera toward an interesting target object in the visual field as in a human vision system [1]. this redirection is usually referred to as object tracking, where it is the problem of following image elements moving across a video sequence automatically. object tracking is an essential building block for vision systems addressing robotic tasks like visual servoing, pipe and cable inspection, and metrology [2]. many studies considered the object tracking problems. some of the most recent and related papers to the present paper are reviewed. in [3], [4], [5], and [6] object tracking algorithms for mobile robot are developed, where [3] suggested a control technique that end-effecter of manipulator can chase an object using an image gained from a stereo camera installed in a robot platform. the adaptive color matching and kalman filter were used in the proposed algorithm in [4]. in [5], the developed algorithm is based on sensor network, where the occlusion problem is assumed and solved. 3d-object tracker using a new kalmanfilter based framework that carries out fast and accurate rigid object tracking was introduced in [6]. the authors of [7] presented a grasp tracking method to be used in eye-in-hand robot configuration, where it consists of three stages, grasp synthesis, grasp transfer, and grasp analysis. an object tracking method based on image this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ hussam k. abdul-ameer al-khwarizmi engineering journal, vol.6, no.1, pp 31 -47 (2010) 32 segmentation and rough set minimal rule set was presented in [8], where the rough set theory is used to control the camera pose. in [9], the problems of tracking human face using active camera that installed on 2-dof (pan-tilt) platform was discussed, and the kinematics model between object in motion and image of the camera is achieved. in [10],[11],and [12], fuzzy technique is adopted in the developed tracking algorithms, where the author of [10] applied fuzzy method in the cielabcolor space to model target color in a target recentering task using an active camera. fuzzy control system and adaptive rao-black partial filter to track object in 3d space were used in [11]. in [12], texture segmentation approach using both wavelet transform and fuzzy grammar as classifier was introduced. the references [13] and [14] demonstrated multi-sensor fusion in object tracking algorithms, where in [13], the cooperation method of cameras for object tracking was introduced, while [14], presented the localization and object tracking problems using audiovisual measurements, where two microphones are used beside ccd camera to achieve target localization. bionics studies simulating the principles of biologic system principles to build advanced technology systems or enable the artificial technology systems have some characteristics or functions of biologic system [15]. in the following, some of the recent studies that simulating the biological oculomotor system to use in visual tracking applications will be presented. fortunato flores ando and alfredo weitzenfeld ridel [16] introduced a model of the oculomotor system involved in the generation of saccadic and its implementation in a real robot used to keep track of visual input lost due to reorientation. reference [17] presented a new method for visual scanning and target tracking by means of independent pan-tilt cameras, which mimic chameleon visual system. in [18], a discussion of how human eyes track an object by moving the optical axis is presented. reference [15] introduced a visual tracking system for unmanned aerial vehicle (uav) where the principle of biomimetic eye is used. in this paper, an approach for object tracking based on bionics of human eye movements has been introduced and verified experimentally. the proposed tracking method is divided into two stages, saccade and pursuit stages. in the saccade stage, fast searching and tracking algorithm for the observing object is developed, where fuzzy technique is used as decision maker to predicate the proper pan and tilt angles that are needed to direct the camera platform to allow the tracked object to be within the field of camera view. in the second stage, pursuit-tracking algorithm is proposed where a smooth object tracking will occur. the present paper layout is as follows: a description of the human oculomotor system is presented in section two. the proposed tracking approach is illustrated in section three. experimental setup and results with their discussions are shown in sections four and five. finally, conclusions are drawn in section six. 2. human oculomotor system the ocular motor control system is an effective device for capturing an object in the central pits (fovea) of the retinas. human eyes always move their optical axes to keep the image from leaving the central pit, i.e. eyeballs never let an image move freely over the retina. when the fovea of the retina catches a moving target, the oculomotor control system performs different kinds of eye movements according to the position and velocity of the target and head. these movements are produced by contractions of the extrinsic eye muscles, innervated by neurons originating in the brain [18],[19],[20]. figure (1) shows the fovea centralis and the internal anatomy of the eyeball. there are three types of eye movements coordinated by the brain [20]: saccade eye movements are very high velocity movements, 400 to 800 degree per second, of both eyes that target an image on the fovea centralis. smooth pursuit movements are slower (up to 30 degree per second), and match the speed of the moving objects to keep their images at or near the fovea. vergence movements (30 to 150 degree per second) cause the eyes to converge so that an image of an object is brought to the fovea of both eyes, allowing the object to be seen more clearly three-dimensionally. the saccadic movements occurred when an object enters the filed of view, where the projected image of the object will be lied on the periphery area of the retina. this area contains a type of photoreceptors, which allowed the visual cortex to diagnose a non-accurate shape and position of the observing object. the brain will send impulse signals to the eye muscles to actuate the eyeball position to a new position allowing the projected image of the object laying on the fovea, this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ hussam k. abdul-ameer al-khwarizmi engineering journal, vol.6, no.1, pp 31 -47 (2010) 33 which is a pit in the retina containing a rich amount of cones photoreceptors that can give a clear view and accurate location of the seen objects. when the image of object is projected on fovea, a smooth pursuit movement will take place. this movement is coordinated by the brain when the eyes track a moving target smoothly. the developed tracking approach used both saccadic and smooth pursuit principles to achieve object-tracking process. the vergence movements will not considered in this research because a monocular vision system is assumed. fig.1. the internal anatomy of the eyeball [20]. 3. tracking approach in this section, an overview of the developed approach will be presented. the tracking approach assumed a monocular active camera, which is installed on pan/tilt platform. this structure refers to artificial eyeball, where the acquired images from the active camera will process through artificial central processing unit it gives the proper decisions to pan/tilt platform form of angle values and then the platform motors will be actuated based on these values. the process of acquiring and manipulation of the images and giving the instructions to the platform is referred to as visual feedback and it is used widely in the applications of robot tracking. two stages of the tracking method is assumed, fast or saccadic and smooth pursuit. since the human oculomotor system reflects the object image in tracking task on the retina into two regions, periphery and fovea, image plane will be divided into two regions also, periphery and fovea regions, where fast tracking will occur in the periphery region and the smooth tracking will take place at the fovea region. in the saccadic stage, a developed searching algorithm will be applied on the saccadic region to check if the object entered the field of the view. if so, a developed fuzzy decision maker will select the pan and tilt angle values to redirect the artificial eye system in order to put the object within the fovea region. if the object enters the fovea region, the second stage of the tracking approach will be activated. in this stage, the tracked object will be kept in the fovea region by adjusting the pan and tilt angle values of the platform, where a search algorithm based on object centroid is used. figure (2) presents a block diagram of the developed approach. in the following subsections, complete descriptions of saccadic phase, the used fuzzy technique, and smooth pursuit phase will be illustrated. 3.1. saccadic phase in human oculomotor system, saccadic is small jerking movements that rapidly bring eye from one fixation point to another and allow search of the visual field [21]. during a saccade, the oculomotor system operates in an open-loop mode this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ hussam k. abdul-ameer al-khwarizmi engineering journal, vol.6, no.1, pp 31 -47 (2010) 34 because the information from the retina and muscle proprioceptors is not transmitted quickly enough during the eye movement for use in altering the control signal [22]. for that, openloop mode will be considered in the saccadic phase of the tracking approach. fig.2. the proposed approach for object tracking. digital video camera two successive images are captured image values are binaries the binaries images will be subtracted weight factors are calculated for the resulted image the proposed fdm pan and tilt angle values will obtain if wfn≠0 is motion detected in fovea image is captured and binaries the edges of the observing object are detected the object cop is calculated if abs(copx,y− cofx,y) ≠ 0 pan and tilt angle values will calculate control software of pan/tilt unit parallel interface card (pan/tilt) unit saccadic pursuit control part image is captured and binaries this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ hussam k. abdul-ameer al-khwarizmi engineering journal, vol.6, no.1, pp 31 -47 (2010) 35 the image plane, artificial retina, is divided into two regions, saccadic and fovea, where at saccadic region the saccadic tracking phase will be applied, while the smooth pursuit-tracking phase will occur in the fovea region. figure (3) presents the proposed divisions of the image plane, where the saccadic region is divided into four zones. these zones are analogue to the periphery area of retina. weight factor will be introduced at each zone to give an indication about the amount of the object that is entered in each zone. this weight factor can mathematically be presented as the ratio of the summation of the white pixels, object pixels, in each zone to the total number of pixels in the zone. equation (1) presents this relation: n zz n z yxi wf  ),( …(1) where: ),( zz yxi is the pixel value at each zone and the subscript (n) refer to zone number. z is the total number of pixels at each zone. fig.3. the proposed divisions of image plane. the weight factor may have any value between 0 to 1, where zero value means no object entered the zone, while one value points to the object that entered the whole zone. interference between object and background pixels may occur. to minimize the effect of the interference, a subtraction process between successive frames will be adopted and the gained image will be used to calculate the weight factors. this process can be expressed as follow: ),(),(),( ''' yxiyxiyxi  …(2) where the super scribe presents the image function after a certain period. the weight factors for the saccadic zones will be used to give the proper pan and tilt angle values that are used to drive the camera platform to a new location. the selection of the pan and tilt angle is based on logical statements, where table (1) shows the required logical values of pan and tilt when the object enters saccadic zones individually. to clarify this, assume the weight factor of the first zone indicates a value, so, to redirect the camera platform to allow the object to be in the fovea region, positive pan and negative tilt angle values are needed. the amounts of these values depend on the weight factor value, where a large weight factor means a large increase in angles value. table 1, the required logical values of pan and tilt when the observing object enters the saccadic zones individually. weight factor weight factor value pan value tilt value wf1 nil nil nil 0.25 positive small negative small 0.5 positive middle negative middle 0.75 positive large negative large wf2 nil nil nil 0.25 negative small negative small 0.5 negative middle negative middle 0.75 negative large negative large wf3 nil nil nil 0.25 negative small positive small 0.5 negative middle positive middle 0.75 negative large positive large wf4 nil nil nil 0.25 positive small positive small 0.5 positive middle positive middle 0.75 positive large positive large when two weight factors have values; i.e. the object enters two zones; new logical statements -t ilit − tilt (cw) +pan (ccw) − pan (cw) + tilt (cw) this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ hussam k. abdul-ameer al-khwarizmi engineering journal, vol.6, no.1, pp 31 -47 (2010) 36 are needed to be added. if three weight factors indicate certain values, zoom out is required because the object is large. however, this case is limited because the large object will lie on the fovea region; therefore, there is no need to the saccadic phase. since, the selection of the pan and tilt angle values needs a combination between two or more of the logical statements when the object enters more than one zone, fuzzy logic will be used as a decision maker to select the proper pan and tilt values. 3.2. fuzzy-based decision making (fdm) the fdm was used to choose the pan and tilt angle values based on the weight factors of the saccadic zones. figure (4) shows a block diagram of the fdm, where four linguistic variables (lvs) were used as input to the fdm and two (lvs) were used as output. the input (lvs) are the weight factors and the output (lvs) are pan and tilt angles. both input and output (lvs) used five different fuzzy sets for each input and output. these sets are out, in small, in middle, in large, and in for the input (lvs) and negative large (negl), negative small (negs), zero, positive small (poss), and positive large (posl) for the output (lvs). in figure (5), the membership functions of the input and output (lvs) are illustrated, where triangular shape was adopted to present the membership function. the developed rule base consists of 81 rules, where table (2) shows sparse rules of the developed rules. the singleton technique was used for fuzzification and the adopted fuzzy inference method is mamdain’s, while the defuzzification is the center of gravity method. fig.4. block diagram of the fdm. fig.5. the proposed membership functions of the input and output linguistic variables. weight factor (wf1) weight factor (wf2) weight factor (wf3) weight factor (wf4) fu zz if ic at io n (s in gl et on ) inference mechanism (mamdain’s) rule-base d ef uz zi fi ca ti on (c o g ) pan angle (deg.) tilt angle (deg.) this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ hussam k. abdul-ameer al-khwarizmi engineering journal, vol.6, no.1, pp 31 -47 (2010) 37 table 2, sparse rules of the developed fdm. input of fdm output of fdm wf1 wf2 wf3 wf4 pan tilt in middle nil nil nil poss negs in small in middle nil nil negs negs nil in small in large nil negs poss nil in middle in middle nil negs nil nil nil in in small negl posl nil nil in large in middle negs poss in large nil nil in large posl nil in nil nil in posl nil 3.3. smooth pursuit phase this phase will be activated when the object enters the fovea region, where fovea in human eyeball is a pit in retina that contains a dense amount of photoreceptors. the important task here is to keep the object in the fovea region otherwise saccadic phase will be reactivated. the developed algorithm for this phase is based on detecting the object edges and then locating the center of the perimeter (cop) of it. this process will be repeated for the next frame. the path between cop and the center of fovea region (cof) will give the orientation of the pan and tilt angles, where figure (6) presents the logical orientation of them based on determining the direction of the path between cop and cof. since the orientations of the angles are obtained, the values of pan and tilt are needed to be determined, where these values depend on different parameters. the most significant parameters are the velocity and the acceleration of the object. in addition, the extrinsic parameters of camera, such as resolution and focal length, can play an important role in this phase. in terms of mathematics, the angles value can be expressed as follow: ),( camo fvfangle  …(3) where: ov is the object velocity camf is the camera extrinsic parameters. equation (3) is an empirical function and depends on the selection of camera specifications, boundary conditions of the fovea region, lighting conditions, image digitization, and environmental noise. however, in this paper fixed and controlled conditions will be assumed in this phase. fig.6. the logical orientation of the pan and tilt angles in fovea region. 4. experimental setup an experimental setup was developed to verify the proposed approach. it consists of pan / tilt unit type (luntai pts 302), where it has two rotational joints, one perpendicular to the other in order to simulate the pan and tilt motions of a real eye. digital video camera type (panasonic nvgs25) is used as an image acquiring device, where it is held on the pan/tilt unit and linked with pc computer using hi speed usb link. the images are digitized at 720×576 and the fovea region is selected as 240×192. interface card between the pan/tilt unit and pc is built in order to control the pan/tilt unit via matlab environment. figure (7) presents a photograph of the developed experimental setup. 5. results and discussions in this section, the proposed method for object tracking is verified using the developed experimental setup. the algorithm of the tracking approach was written using (matlab-ver. 7.3) environment. each phase of the approach is verified separately. in the following subsections, the results and their discussions will be presented. cof if cop in (1) quarter then -pan (cw) -tilt (cw) if cop in (4) quarter then -pan (cw) +tilt (ccw) if cop in (3) quarter then +pan (ccw) +tilt (ccw) if cop in (2) quarter then +pan (ccw) -tilt (cw) this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ hussam k. abdul-ameer al-khwarizmi engineering journal, vol.6, no.1, pp 31 -47 (2010) 38 control apparatus on (pan\tilt) unit – consists of interfacecard and power supply. digital video camera (pan / tilt) unit the observing object fig.7. photograph of the developed experimental setup. 5.1. saccadic phase eight different cases are adopted to investigate this phase. in each case, part of the observing object is appeared in the image plane. figure (8) shows the adopted cases. a circular plane object is used as the observing object where its diameter is 8 cm. to scrutinize the effect of object enlargement on the proposed approach, three different locations are used for the (camera/(pantilt unit)) (cpt) configuration, where the distance between each location is 10 cm. fig.8. the selected cases to investigate saccadic phase. case1: in this case, a part of the observed object is laid in the upper left corner of the image plane. this area belongs to the first saccadic zone and the proposed approach will respond by giving the proper pan and tilt angle values to put the object in fovea region. figure (9) shows the output results of the saccadic phase for the three different locations of the cpt configuration, where it presents the relation between the pan and tilt values with frame number. from figure (9), the absolute values of pan and tilt angles of the first frame are matched, while the sign of tilt angle is negative and it shows that the object is laid in the first zone of the saccadic region. this result conforms the operation of developed fdm. figures (9 b and c) show different behavior form figure (9-a), where this is related to different reasons. the first one is object enlargement that results from decreasing the distance between the object and the cpt configuration, which may cause the weight factors of the saccadic zones to increase. this increasing will have an effect on the outputs, pan and tilt angles, of the fdm. the second reason is the initial values of the pan and tilt angles, where these values may cause transferring the object form a certain zone to another or may cause the object to lie between two zones that make the fdm give diverse outputs for each case. in addition, noise that comes from light condition and object projection on the image plane may increase or decrease the fovea region case 1 case 6 case 7 case 5 case 8 case 2 case 3 case 4 zone 1 zone 2 zone 3zone 4 this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ hussam k. abdul-ameer al-khwarizmi engineering journal, vol.6, no.1, pp 31 -47 (2010) 39 weight factors of the saccadic zones and this will change the outputs of the fdm. however, the total net values of the pan and tilt angles has nearly similar values for the cases (a), (b), and (c) of figure (9) and that indicates the robustness of the developed approach to object enlargement problem. it can be seen from figure (9) that the number of frames that are required to put the object in fovea region does not exceed four frames for all location cases. this result indicates the acceptable response of the developed approach. fig.9. results of case 1-saccadic phase. case2: in this case, part of the observed object is laid in two zones (1 and 2) of the saccadic region. figure (10) shows the obtained results of this case, where the optimal response of this case can be considered as changing in tilt values and that is presented in figure (10-a). in other figures (10-b and c), varying in pan values can be recognized. the enlargement of the object causes this varying where the weight factors of the zones (1 and 2) are increased and the rules of the fdm will add an additional amount of the pan angle value. however, the total net values of the pan angle for each location case of case 2 is close to zero or can be neglected. fig.10. results of case2 –saccadic phase. case 3: the object in this case is laid in the upper-right side of the image plane. figure (11) shows the experimental results of this case, where it can be observed that in the first frame the values of the pan and tilt angles are identical. this is caused by laying the object in the second zone of the saccadic region. the fdm responded ideally in this case. in figure (11-c), fluctuation in the angle values could be recognized and the number of frames that are required to put the object in fovea region is increased from that which is stated in figures (11-a and b). this behavior can be explained as follows: the first angle values are large because the influence of the object enlargement. these large values will put the object in the third zone of the saccadic region. then the object will lie in the first saccadic zone because of the pan and tilt angle values, as shown in figure (11-c). this object fluctuation between the first and third zones will continue until the object is laid completely in fovea region. 12.23 6.23 0.06 0.02 0.01 0 0 -12.23 6.23 -0.29 -0.13 -0.01 0 0 -15 -10 -5 0 5 10 15 1 2 3 4 5 6 7 frame number a n g le v a lu e ( d e g .) pan tilt 5.69 9.63 8.88 0 0 0 0 0 -5.69 -9.63 8.88 0 0 0 0 0 -15 -10 -5 0 5 10 15 1 2 3 4 5 6 7 8 frame number a n g le v a lu e ( d e g .) pan tilt 8.91 11.54 -0.4 0 0 0 0 0 0 -8.91 -4.56 6.45 0 0 0 0 0 0 -10 -5 0 5 10 15 1 2 3 4 5 6 7 8 9 frame number a n g le v a lu e ( d e g .) pan tilt (a) 50 cm far from object (c) 30 cm far from object (b) 40 cm far from object 0 0 0 -6.12 -3.88 0 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 frame number a n g le v a lu e ( d e g .) pan tilt (a) 50 cm far from object -9.66 4.69 0.17 0.12 0.02 0 -12.02 3.15 -0.17 -0.12 -0.02 0 -15 -10 -5 0 5 10 1 2 3 4 5 6 frame number a n g le v a lu e ( d e g .) pan tilt (c) 30 cm far from object -3.47 2.92 0 0 0 0 -6.75 -2.92 0 0 0 0 -8 -6 -4 -2 0 2 4 1 2 3 4 5 6 frame number a n g le v a lu e ( d e g .) pan tilt (b) 40 cm far from object this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ hussam k. abdul-ameer al-khwarizmi engineering journal, vol.6, no.1, pp 31 -47 (2010) 40 fig.11. results of case3 –saccadic phase. case4: in this case, part of the object is placed in the middle-left side of the image plane. the ideal response of the fdm to this case is by giving a value to the tilt angle only. from figure (12), it can be seen that in the first case the tilt angle is less than 1 degree. however, the fdm gives a value to the tilt angle for other location cases that are presented in figures (12b and c) and in the next frames in figure (12-a). this manner of acting is caused due to unavailable knowledge of the object size that is similar to human response in the saccadic movement. the overall tilt values for all cases presented in figure (12) are less than 1.5 degree and that shows the adaptability of the developed approach to the object size. case 5: this case is the mirror to case 4, where the object is laid in the second and third zones of the saccadic region. from figure (13), the response of the fdm is ideal, where the maximum tilt value does not exceed 2.2 degree and the overall tilt values for each location case of figure (13) is less than 0.4 degree. fig.12. results of case 4 –saccadic phase. fig.13. results of case5 –saccadic phase. -12.31 -7.35 0.82 0 -0.01 0 -12.31 7.35 -3.59 0 -0.01 0 -15 -10 -5 0 5 10 1 2 3 4 5 6 frame number a n g le v a lu e ( d e g .) pan tilt -9.48 -6.76 0 0 0 0 -9.48 1.56 0 0 0 0 -12 -10 -8 -6 -4 -2 0 2 4 1 2 3 4 5 6 frame number a n g le v a lu e ( d e g .) pan tilt (b) 40 cm far from object (a) 50 cm far from object -15.74 -14.86 19.87 -13.05 4.26 0.23 0.09 0.07 0.02 -15.74 16.48 -19.87 12.98 -3.87 0.24 0.09 0.07 0.02 -30 -20 -10 0 10 20 30 1 2 3 4 5 6 7 8 9 frame number a n g le v a lu e ( d e g .) pan tilt (c) 30 cm far from object zone 1 zone 3 zone 1 zone 3 5.26 8.87 9.21 -6.04 0 0 0 0 2.27 -6.66 9.21 -6.04 0 0 0 0 -10 -5 0 5 10 15 1 2 3 4 5 6 7 8 frame number a ng le v al ue (d eg .) pan tilt (b) 40 cm far from object 9.39 12.08 -7.26 14.8 -16.57 17.43 -12.79 2.84 -0.92 0-1.2 4.39 -8.37 14.8 -16.57 17.43 -12.79 3.99 -1.5 0 -20 -15 -10 -5 0 5 10 15 20 1 2 3 4 5 6 7 8 9 10 fr ame number a ng le v al ue (d eg .) pan tilt (c) 30 cm far from object 7.41 10.19 6.58 -5.19 0.54 0.11 0 0 0-0.92 4.29 -6.58 5.19 -0.75 -0.11 0 0 0 -10 -5 0 5 10 15 1 2 3 4 5 6 7 8 9 frame number a n g le v a lu e ( d e g .) pan tilt (a) 50 cm far from object -5.65 -7.26 -5.27 0 0 0-0.21 1.09 -1.74 0 0 0 -8 -6 -4 -2 0 2 1 2 3 4 5 6 frame number a ng le v al ue (d eg .) pan tilt (b) 40 cm far from object -5.65 -13.66 -1.47 0 0 0 -1.01 2.1 -1.47 0 0 0 -15 -10 -5 0 5 1 2 3 4 5 6 frame number a ng le v al ue (d eg .) pan tilt (c) 30 cm far from object -6.83 -9.96 -1.39 0 0 0 -0.75 2.19 -1.37 0 0 0 -12 -10 -8 -6 -4 -2 0 2 4 1 2 3 4 5 6 frame number a ng le v al ue (d eg .) pan tilt (a) 50 cm far from object this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ hussam k. abdul-ameer al-khwarizmi engineering journal, vol.6, no.1, pp 31 -47 (2010) 41 . fig.14. results of case6 –saccadic phase. fig.15. results of case7 –saccadic phase. cases 5, 6, and 7: these cases are similar to cases (1,2, and 3), where the same behavior in general can be noticed as shown in figures (14,15, and 16) respectively. however, figure (16-c) presents the outputs of the third location case of case 7; the fdm failed to put the object in the fovea region. this miss tracking can relate to the effect of object enlargement. however, the tracking of large objects in human oculomotor system will be in fovea and no saccadic movements are necessary. fig.16. results of case8 –saccadic phase. 5.2. smooth pursuit phase this phase is verified using the developed experimental setup. the proposed algorithm is based on minimizing the difference between the center of object perimeter (cop) and the center of fovea region (cof). in mathematic expression: 0cofcop ,,  yxyx …(4) the acceptable error value of equation 4 will be selected to 10 pixels. in the adopted tests, 10 pixels are less than 4 mm in real environment; i. e., if the object moves more than 4 mm, the cpt (c) 30 cm far from object 10.15 11.46 0 0 0 0 0 10.15 -0.77 0 0 0 0 0 -5 0 5 10 15 1 2 3 4 5 6 7 frame number a n g le v a lu e ( d e g .) pan tilt 4.83 14.89 3.78 0 0 0 0 0 4.83 14.89 -9.47 0 0 0 0 0 -15 -10 -5 0 5 10 15 20 1 2 3 4 5 6 7 8 frame number a n g le v a lu e ( d e g .) pan tilt (a) 50 cm far from object 11.78 7.74 -4.36 2.23 0 0 0 0 0 11.78 -7.74 6.92 -2.23 0 0 0 0 0 -10 -5 0 5 10 15 1 2 3 4 5 6 7 8 9 frame number a n g le v a lu e ( d e g .) pan tilt (b) 40 cm far from object -4.35 0.73 0.56 0.3 0 0 10.25 0.53 -0.09 -0.06 0 0 -10 -5 0 5 10 15 1 2 3 4 5 6 frame number a n g le v a lu e ( d e g .) pan tilt (c) 30 cm far from object -7.67 1.34 0.47 0 0 0 0 9.76 0.78 -0.34 0 0 0 0 -10 -5 0 5 10 15 1 2 3 4 5 6 7 frame number a n g le v a lu e ( d e g .) pan tilt (b) 40 cm far from object -7.42 2.45 0.01 0.02 0.01 0.02 0.01 9.91 0.12 0.01 0.02 0.01 0.02 0.01 -10 -5 0 5 10 15 1 2 3 4 5 6 7 frame number a ng le v al ue (d eg .) pan tilt (a) 50 cm far from object -9.55 -7.62 -6.81 6.87 -4.74 3.14 0 0 0 9.55 3.45 -7.05 6.87 -5.87 3.14 0 0 0 -15 -10 -5 0 5 10 15 1 2 3 4 5 6 7 8 9 frame number a n g le v a lu e ( d e g .) pan tilt (b) 40 cm far from object -12.14 -14.34 16.4 -25.17 -9.86 -30 12.14 -12.38 16.4 -25.17 -9.86 -30 -40 -30 -20 -10 0 10 20 1 2 3 4 5 6 frame number a n g le v a lu e ( d e g .) pan tilt (c) 30 cm far from object -10.25 -8.74 0 0 0 0 10.25 0.46 0 0 0 0 -15 -10 -5 0 5 10 15 1 2 3 4 5 6 frame number a ng le v al u e (d eg .) pan tilt (a) 50 cm far from object this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ hussam k. abdul-ameer al-khwarizmi engineering journal, vol.6, no.1, pp 31 -47 (2010) 42 configuration needs to change its pan and tilt angles in order to keep equation (4) within 10 pixels error. the same circular object that is used in saccadic phase is adopted in this phase. the directions of the pan and tilt angles are selected depending on figure (6). the absolute values of the pan and tilt angles are calculated based on calibration process between visual domain and real world domain. the same locations of the cpt configuration used in saccadic phase are used in this phase. to verify the robustness of the developed algorithm, the cpt configuration will be moved manually in two directions. the first direction is from left to right and from right to left, while the second one is from down to upward and from up to downward. the total distance that the cpt configuration will move is about 30 cm for each case. the cofx and cofy are 120 and 96 pixels respectively. left – right case: figure (17) shows the relation between pan and tilt angles with frame number for different locations of the cpt configuration. in addition, it presents the relation between the object cop and frame number. it can be seen from figure (17-a), the initial values of the pan and tilt are small and can be neglected because the object is laid in the fovea region and the difference value between the cop of the object and the cof is less than 10 pixels. however, in figures (17-b and c), the location of the object needs an adjustment because the difference value is larger then 10 pixels. the cpt configuration is moved to the right and the proposed algorithm will respond by changing the values of pan angle to prevent the object from leaving the fovea region, where the net variation of the pan angle is positive. after that, the cpt configuration moves backward to the initial location, where the average change in the pan values is negative. the observed object is always in fovea region during this verification, where the influence of location of the cpt configuration is limited on the approach as shown in figure (17). however, ripples in the angles values can be recognized, where the manual movement of the cpt configuration causes these ripples. up – down case: in this case, the cpt configuration will be moved in an upward direction until it reaches 15 cm from the initial position and then back to its initial location. figure (18) shows the verification results of this case, where tilt values are changed in the same behavior that pan angle was changed in the previous case. from figure (18), it can be noticed that the pan values are changed while the ideal situation assumed no change. this is because of the manual movement of the cpt configuration that makes the moving track not straight, where the pan angle is needed to correct such movements. 6. conclusions in this paper, an approach for object tracking was proposed and verified experimentally. the main conclusions of this research are: 1. both tracking phases showed beneficial results and robust response to the object enlargement and digital noise. 2. the use of fdm in the saccadic phase is beneficially and it accelerates the response of the approach to meet its goal in few frames. however, the adjustment of the output membership functions may reduce the effect of the object enlargement. 3. the smooth pursuit phase showed efficient smooth tracking of the observing object, however, calibration process between the real and visual domains is necessary. in general, the proposed approach can be used with confidence in robot applications. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ hussam k. abdul-ameer al-khwarizmi engineering journal, vol.6, no.1, pp 31 -47 (2010) 43 fig.17. results of right-left case-pursuit phase. 0 50 100 150 200 1 34 67 100 133 166 199 232 frame number p ix el copx copy p ix el frame number -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 1 30 59 88 117 146 175 204 233 frame number a n g le v a lu e ( d e g .) pan tilt a ng le v al ue ( d eg .) frame number 0 50 100 150 200 1 59 117 175 233 291 349 407 465 frame number p ix e l copx copy frame number pi xe l -3 -2 -1 0 1 2 3 1 56 111 166 221 276 331 386 441 frame number a n g le v a lu e ( d e g .) pan tilt a ng le v al ue ( d eg .) frame number 0 50 100 150 200 1 29 57 85 113 141 169 197 225 frame number p ix el copx copy frame number pi xe l -2.5 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 1 28 55 82 109 136 163 190 217 frame number a n g le v a lu e ( d e g .) pan tilt a ng le v al ue ( d eg .) frame number (b) 40 cm far from object (c) 30 cm far from object (a) 50 cm far from object this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ hussam k. abdul-ameer al-khwarizmi engineering journal, vol.6, no.1, pp 31 -47 (2010) 44 fig.18. results of up-down case-pursuit phase. -1.5 -1 -0.5 0 0.5 1 1.5 2 2.5 1 33 65 97 129 161 193 225 257 frame number a n g le v a lu e (d eg .) pan tilt a ng le v al ue ( d eg .) frame number 0 20 40 60 80 100 120 140 160 1 35 69 103 137 171 205 239 frame number p ix el copx copy frame number pi xe l (a) 50 cm far from object -1.5 -1 -0.5 0 0.5 1 1.5 2 1 21 41 61 81 101 121 141 161 frame number a n g le v al u e (d eg .) pan tilt a ng le v al ue ( d eg .) frame number 0 20 40 60 80 100 120 140 160 1 23 45 67 89 111 133 155 177 frame number p ix el copx copy frame number pi xe l (c) 30 cm far from object -2 -1.5 -1 -0.5 0 0.5 1 1.5 1 32 63 94 125 156 187 218 249 frame number a n g le v a lu e ( d e g .) pan tilt a ng le v al ue ( d eg .) frame number 0 20 40 60 80 100 120 140 160 180 1 32 63 94 125 156 187 218 249 frame number p ix el copx copy frame number pi xe l (b) 40 cm far from object this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ hussam k. abdul-ameer al-khwarizmi engineering journal, vol.6, no.1, pp 31 -47 (2010) 45 7. references [1] won-cheol kim, jung-hwan kim, minho lee, jang-kyoo shin, hyun-seung yang, and hiroo yonezu, “smooth pursuit eye movement system using artificial retina chip and shape memory alloy actuator,” ieee sensors j., vol. 5, no. 3,pp. 901-509, june 2005. [2] emanuele trucco and konstantinos plakas, “video tracking: a concise survey,” ieee j. of oceanic engineering, vol. 31, no. 2, pp. 520-528, april 2006 [3] kwang-hee lee, do-eun kim, sang hwa lee, young-ho lee, and tae-yong kuc, “visual servoing of 8-dof arm for mobile robot platform,” int. conf. on control, automation and systems, in coex, seoul, korea, oct. 14-17, 2008, pp. 2176-2180. [4] lin rui, du zhijiang, he fujun, kong minxiu, and sun lining, “tracking a moving object with mobile robot based on vision,” ieee/wcci, int. conf. on neural networks, 1-8 june 2008, pp. 716 – 720. [5] j. takahashi, m.d. rokunuzzaman, k. sekiyma, and t. fukuda, “mobile robotic sensor network using vision tracking,” ieee/sice int. sympo. on system integration, 4-4 dec. 2008, pp. 117 – 122. [6] youngrock yoon, akio kosaka, and avinash c. kak, “a new kalman-filter-based framework for fast and accurate visual tracking of rigid objects,” ieee trans. on robotics, vol. 24, no. 5, pp.12381251, oct. 2008. [7] gabriel recatal´a, raffaella carloni, claudio melchiorri, pedro j. sanz, enric cervera, and a´ ngel p. del pobil, ”vision-based grasp tracking for planar objects,” ieee trans. on systems, man, and cybernetics—part c: applications and reviews”, vol. 38, no. 6, pp. 844-849, nov. 2008. [8] shijie dai, weiguo ren, fenglong gu, he huang, and shuying chang, “implementation of robot visual tracking system based on rough set theory” ieee/fskd fifth international conference on fuzzy systems and knowledge discovery, vol. 2, 18-20 oct. 2008, pp. 155 – 160. [9] diansheng chen, feng bai, yi xie, and tianmiao wang, “tracking system of motion object for scout robot,” ieee/robio int. conf. on robotics and biomimetics, 22-25 feb. 2009, pp.1111 – 1116. [10] francisco j. montecillo-puente, víctor ayala-ramírez, arturo pérez-garcía and raú 1 e. sánchez-yáňez, “fuzzy color tracking for robotic tasks,” ieee int. conf. on systems, man and cybernetics, vol. 3, 58 oct. 2003, pp. 2769 – 2773. [11] suk-bum kang and tae-kyu yang, “tracking for moving object using adaptive rao-blackwellized particle filter and fuzzy control system,” ieee/ iccas int. conf. on control, automation and systems, 17-20 oct. 2007, pp. 420 – 424. [12] manuel j. ferreira, cristina p. santos, and joao monteiro, “texture cue based tracking system using wavelet transform and a fuzzy grammar,” ieee int. conf. on industrial informatics, vol. 1, 23-27 june 2007 pp. 393 – 398. [13] kazuyuki morioka, szilveszter kovacs, joo-ho lee, peter korondi, and hideki hashimoto, “fuzzy-based camera selection for object tracking in a multicamera system,” ieee int. conf. on human system interactions, 25-27 may 2008, pp.767 – 772. [14] huiyu zhou, murtaza taj, and andrea cavallaro, “target detection and tracking with heterogeneous sensors,” ieee j. of selected topics in signal processing, vol. 2, no. 4, pp. 503-513. aug. 2008. [15] hairong zou, zhenbang gong, shaorong xie, and wei ding, “a pan-tilt camera control system ofuav visual tracking based on biomimetic eye,” ieee int. conf. on robotics and biomimetics, 17 – 20 dec. 2006, pp.1477-1482. [16] fortunato flores ando and alfredo weitzenfeld ridel,“visual input compensation using the crowley-arbib saccade model,” ieee int. conf. on advanced robotics, 8-20 july 2005, pp. 476 – 483. [17] ofir avni, francesco borrelli, gadi katzir, ehud rivlin, and hector rotstein, “scanning the environment with two independent cameras biologically motivated approach,” ieee/ rsj int. conf. on intelligent robots and systems, 9 15 oct. 2006, pp. 5297-5302. [18] xiaolin zhang, “an object tracking system based on human neural pathways of binocular motor system,” ieee int. conf. on control, automation, robotics and vision, 5-8 dec. 2006, pp. 1 – 8. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ hussam k. abdul-ameer al-khwarizmi engineering journal, vol.6, no.1, pp 31 -47 (2010) 46 [19] hairong zou, “modeling and simulation of the oculomotor control system,” ieee int. conf. on bioinformatics and biomedical engineering, 16-18 may 2008 pp. 853 – 856. [20] s. i. fox, human physiology.9th edition, mcgrawhill, 2006. [21] a. vander, j. sherman, and d. luciano, human physiology. 8th edition, mcgrawhill, 2001. [22] joseoh d. bronzino, the biomedical engineering handbook. 2nd edition, crc press, 2000. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ )2010( 47 31فحة ، ص1، العدد 6مجلة الخوارزمي الھندسیة المجلد حسام كاظم عبد األمیر 47 لتتبع األجسام لالستخدام في) bionics(طریقة مقترحة باعتماد تطبیقات اإلنسان اآللي حسام كاظم عبد األمیر جامعة بغداد/ كلیة الھندسة الخوارزمي /لطب الحیاتياقسم ھندسة ةصالخال ا زئیین , تناول البحث اقتراح طریقة لتتبع األجسام مستوحاة من نظام الرؤیا البشري و التحقق منھا عملی ى ج ة إل ة المقترح مت الطریق ث قس و , حی األول ھ ).smooth pursuit(و الثاني المالحقة الھادئة ) saccadic phase(التتبع السریع زئیین اطق ) saccadic region(األول , قسم مستوى الصورة و الذي یماثل شبكیة العین البشریة إلى ج ذه المن اطق وھ ھ من ى أربع م إل دوره قس ذي ب و ال ة . حیث یتم فیھ الجزء الثاني من عملیة التتبع) fovea region(في شبكیة العین و الثاني ) periphery(تقابل منطقة م منطق دخل الجس دما ی ) saccadic(عن بب ) tilt(و) pan(من خالل تغییر قیم زوایا ) fovea(یبدأ النظام المعد بتتبع الجسم و إدخالھ إلى منطقة ق المض تخدام المنط الل اس ن خ ر م و یتم ھذا التغیی ن ) fovea(المقترحة ینشط عند دخول الجسم منطقة الجزء الثاني من الطریقة . كأسلوب اتخاذ قرار ذكي حیث اعد مجموعة شروط منطقیة لذلك ھ م و خروج م و ) tilt(و) pan(حیث یتم الحفاظ على الجسم داخل تلك المنطقة من خالل تغییر قیم زوایا ) saccadic(منطقة یط الجس ز مح وفق طریقة الفروق بین مرك ة ز منطق ام ). fovea(مرك ى نظ ا عل ة عملی ة المقترح ت الطریق ا ) camera-pan/tilt(طبق ة الرؤی ین قابلی دة لتحس ائج جی رت نت رض و أظھ ذا الغ د لھ اع . ة لإلنسان اآللي المماثل لإلنساناالصطناعی this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 5, no. 4, pp 58-68 (2009) health monitoring for cantilever crane frame using residual error method nabil h. hadi iqbal a. rashed department of nuclear engineering/ college of engineering/ university of baghdad (received 5 march 2008; accepted 13 juneuary 2008) abstract in the present research, a crane frame has been investigated by using finite element method. the damage is simulated by reducing the stiffness of assumed elements with ratios (10% and 20 %) in midspan of the vertical column in crane frame. the cracked beam with a one-edge and non-propagating crack has been used. six cases of damage are modeled for crane frame and by introducing cracked elements at different locations with ratio of depth of crack to the height of the beam (a/h) 0.1, 0.20. a fem program coded in matlab 6.5 was used to model the numerical simulation of the damage scenarios. the results showed a decreasing in the five natural frequencies from undamaged beam which means the indication of presence of the damage. the direct comparison gives an indication of the damage but the location of the damage, is not detected. the method based on changes in the dynamics characteristics of the beam structures are examined and evaluated for damage scenarios. the results of the analysis indicate that the residual error method performs well in detecting, locating and quantifying damage in single and multiple damage scenarios. keywords: damage, crack, damage location, beam, error, frequencies. 1. introduction in general, the structures are submitted during their useful life to deterioration processes that, depending on the intensity, may affect their performance and load capacity and consequently their safety. in this case, it is necessary to accomplish an inspection in order to evaluate the conditions of the structure and to locate and quantify the intensity of the damage. the ability to monitor a structure and detect damage at the earliest possible stage is of outmost importance in mechanical, civil and aerospace engineering communities. structural damage is considered as a weakening of the structure that negatively affects its performance. damage may be also defined as any deviation in the structural original geometric or material properties that may cause undesirable stresses, displacements, or vibrations on the structure. these weakening and deviation may be due to cracks, loose bolts, broken welds, corrosion, fatigue, etc. [1]. many structural components are now decaying because of age, deterioration, and lack of maintenance or repair. current nondestructive damage detection (ndd) technique are either visual or are based on experimental methods. visual inspection has always been the most common method used in detecting damage in a structure, but the size and degree of complexity of today’s structures being built provide less scope for visual inspections. the experimental methods such as acoustic or ultrasonic techniques, magnetic field procedure, radiography, eddy current, etc. all of these experimental methods require that the damaged region be identified a priori, and that the segment of the structure being examined must be easily accessible, subjected to these limitations, these methods can detect on or near the surface of the structure. the methods are obviously “local” inspection approaches [2]. one way to overcome the previously mentioned limitations is by using global damage detection methods. structural damage identification based on changes in dynamic characteristics provides a global way to evaluate the structural condition. these methods are based on the idea that modal parameters (i.e., natural nabil h. hadi al-khwarizmi engineering journal, vol. 5, no. 4, pp 58-68 (2009) 59 frequencies, mode shapes and modal damping ratio) are a function of the physical properties of the structure stiffness, damping, mass and boundary conditions [3]. therefore, changes in the physical properties will cause detectable changes for the changes in the modal parameters. the parameterized stiffness, damping and mass matrices of the finite element model are determined using input residuals in the frequency domain. in spite of common model reduction techniques, the projective input residual method serves for the adjustment of incomplete measured response data with regard to the number of degrees of freedom of the finite element model. the major advantage of the method is its sensitivity to modifications in system parameters, thus providing high prediction accuracy for the estimates of such parameters [4]. in this study, a method to identify and to quantify damage in structures, called residual error method in the movement equation [5] is evaluated, by a numerical analysis, to verify its efficiency when applied to crane frame structures. this method is based on the alteration, produced by damage, in the dynamic properties of the structures. the location of the damage is done observing the error in the movement equation of the intact structures. the structures are discretized in finite elements and the damage is introduced by a stiffness and area reduction of the elements’ cross-sections. observing the obtained results, the residual error method in the movement equation is efficient in the damage location and quantification of the studied structure. 2. modeling the stiffness matrix of the cracked element it is assumed that the damage in the beam structure will affect only the stiffness matrix and not to the mass matrix. this assumption is consistent with those used by [6] and [7]. the beam is divided into elements and the behavior of the elements located to the right of the cracked element regarded as external forces applied to the cracked element, while the behavior of elements situated to its left as constraints, see fig.1. thus the flexibility matrix of a cracked element with constraints can be calculated. the strain energy of undamaged element in case of bending [8] is:  l ei dxm w 0 2 1)0( 2 …(1) )(1 mpxm  …(2) substitute eq. (2) in (1) to get dx ei mpx w l    0 2 )0( 2 )( …(3)        lmpml lp ei w 22 32 )0( 32 1 …(4) where: :)0(w the strain energy of undamaged element. :e elastic modulus. :i moment of inertia of undamaged element. :l length of the finite element. :p internal shear force at the right end of beam. :m internal bending moment at the right end of beam. 11  iiii uu  1 1 2 22 3 4 612 264 612612 ][                     i i i i u u u lsym l lll ll l ie k   …(5) the stiffness matrix of undamaged element  uk is the same that developed by [9] for undamaged beam element with rectangular crosssection given by bernoulli-eular theory has two nodes with two degreeof freedoms (2 d. o.f.s),  ,u at each node, as seen in fig. 2, the mass matrix for anelement without crack is …(6) where _ m is the mass per unit length. according to the principle of saint-venant, the stress field is affected only in the region adjacent to crack. however, the calculation of the additional stress energy of a crack has been studied in fracture mechanics and the flexibility coefficient expressed by a stress intensity factor can be derived by                     2 22 _ 4 22156 3134 135422156 420 lsym l lll ll lm m u nabil h. hadi al-khwarizmi engineering journal, vol. 5, no. 4, pp 58-68 (2009) 60 applying the castigliano's theorem in linear-elastic range. fig.1. diagram of a generic element. fig.2. equilibrium condition of a generic element. from the condition of equilibrium, the stiffness matrix of the cracked element in the freefree state can be derived. for a rectangular beam having width b and height h the additional strain energy )1(w due to the crack, [2] can be written as      ac ac dajda a w w 0 0 )1( )1( …(7) where ac is the area of the crack surface. the idea of relating j , strain energy release rate to the stress intensity factor k was proposed by [10] for the three modes, who gave the general formula of j as a function of stress intensity factor k as:        strainplanefor stressplanefor k e k e k e j iiiiii 2 222 1 1 , 1    …(8) where iiiiii kkk ,, is the stresses intensity factors for fracture mode of iii , , iii which are opening, sliding and tearing types respectively, and  is the poisson's ratio. the stress intensity factor ik is: )/( hafak ii  …(9) where i is the stress for the corresponding fracture mode, a is the depth of the crack, )/( haf is the correction factor for the finite specimen. substituting eq. (8) into eq. (7) gives the additional strain energy due to the crack )1(w   da e kv e kk bw iii a p iii 2 0 22 )1( )1()(      where dabda  …(10) eep  for plane stress, )1/( 2veep  for plane strain and b is the width of the beam. the case of plane stress or plane strain, it depends on the dimensions of the beam, and this study take into account the plane stress since the beam is thin (slender) when the length is more than (10) times its least lateral dimensions [8]. taking into account only bending including the opening ( i ) and sliding ( ii ) modes, the eq. (10) becomes; …(11) where iipipim kkk ,, are stress intensity factors for opening-type and sliding mode cracks due to m and p , respectively and by using eq. (9) )()/6( 2 sfabhmk imi  where 12/ 2/ 3hb hm i ym  …(12) )()/3( 2 sfabhplk ipi  where 12/ 2/2/ 3hb hlp i ym  …(13) )()/( sfabhpk iiiip  where hb p a p  …(14)    daekkkbw a piipipim  0 22)1( / x a p m h l l b l m i m i+1 a i 1i pi+1 pi b iu y 1iu x nabil h. hadi al-khwarizmi engineering journal, vol. 5, no. 4, pp 58-68 (2009) 61 where )(sfi and )(sfii are the correction factors for crack mode i and mode ii , )/( has  is defined as the ratio between the crack depth a and the height of the element h , the correction factor from [7] as   )2/cos( 4 )2/sin(1199.0923.0 *)2/tan()/2()(1 s s sssf      …(15) s sss sssiif    1 3 18.0 2 085.0561.0122.1 ) 2 23()( ...(16) and the additional flexibility coefficients due to the presence of the crack )1( ijc are ji ij pp w c    )1(2 )1( …(17) 2,1,,, 21  jimppp substituting eq. (11) into eq. (17) and integrate over the crack height, we get the coefficients )1( ijc which can be expressed in matrix form as             2 1 2 1 2 1 2 2 22 1 2 )1( 3618 189   l ll e ab c p …(18) where 2 11 /)( bhsf and bhsfii /)(2  the total flexibility coefficients ijc for the element with an open crack are )1()0( ijijij ccc  …(19) the total flexibility matrix  c for the element with an open crack can be expressed as      )1()0( ccc  …(20) the stiffness matrix of the cracked element  ck can be written as        t c tctk 1  …(21) with program coded in maple 7, the coefficients of the stiffness matrix  ck are calculated as                44434241 34333231 24232221 14131211 kkkk kkkk kkkk kkkk k c …(22)  ck                 22142414 14111211 24122212 14111211 kkkk kkkk kkkk kkkk …(23) the coefficients values of the matrix ][ ck calculated as in appendix a 3. eigenvalues and eigenvectors for free vibration with undamped system, the equation of motion expressed by matrix form is       0 ..        xkxm ...(24) where: k : stiffness matrix of the system. m : mass matrix of the system.  x : mode shape vector. 0 ..  kxxm …(25) by using eigen value problem algorithm evp, the natural frequencies and mode shapes are obtained. 4. residual error method in the moment equation the residual error method in the movement equation was proposed by [5]. this method is used to identify damage present in a structure and locate it by observing the error present in the movement when the stiffness and mass matrices nabil h. hadi al-khwarizmi engineering journal, vol. 5, no. 4, pp 58-68 (2009) 62 of the undamaged beam and the modal parameters of damaged beam in the crane frame are used. ]])[[]([][][   xmxke uur …(26) where: ].........[ 4321 nr eeeeee  …(27) }..{}.........{}{}[{][ )()3()2()1(    nxxxxx …(28)                    2 2 2 2 1 00 00 00 ][ n       …(29) uk : stiffness matrix of undamaged beam. um : mass matrix of the undamaged beam.  x : damaged mode shape vector. ][  : diagonal natural frequencies. each column of matrix re is a vector corresponding to one mode shape and each value of this vector represents the error that occurs in some positions of the beam, then the highest error will indicate the damage position to a mode shape. this method has been applied for the scenarios which listed in table 2. 5. crane frame a crane frame has been used to study the damage effect on modal parameters (frequencies and mode shapes). the free vibration of a crane frame with and without damage is performed. modal responses of the crane frame are generated using finite element models before and after damaging episode cases. the dimensions and material properties of the crane steel frame are listed in table 1 and fig .3 illustrates the model of the crane frame. table 1, dimensions and material properties for crane frame. vertical column lv = 254 cm horizontal column lh =127 cm cross section width b = 5.08 cm cross section height h = 12.7 cm elastic modulus e = 199.95 gpa mass density  = 7808 kg / m3 fig. 3. crane frame. for finite element analysis purposes, the vertical column in the crane frame is divided into 40 elements and the horizontal column divided into 20 elements. here, six damage scenarios are investigated, as summarized in table 2. in the first two cases (1, 2), the damage is simulated by reducing the stiffness of assumed elements (21). in cases (3 to 6), the damage is simulated in the form of cracks. the finite element model of the beam uses the stiffness matrix of the cracked element described in eq. (30) as in appendix a. table 2, damage scenario for crane frame damage scenario damaged position in vertical column stiffness reduction (%) crack depth ratio a/h case1 21~ (0.5l) 10 case2 21~ (0.5l) 20 case3 21~ (0.5l) 0.1 case4 21~ (0.5l) 0.20 case5 5~(0.125 l),25~ (0.625l) 0.1 case6 5~( 0.125l),25~ (0.625l) 0.20 h b lv lh nabil h. hadi al-khwarizmi engineering journal, vol. 5, no. 4, pp 58-68 (2009) 63 6. results and discussion the results for the first five frequencies are listed in table 3 for the damage scenarios considered in table 2 for crane frames. the results of the proposed method for the damage scenarios case1 and case2 are shown in fig. 4 as in (a) and (b) is calculated using only two modes shapes. the peak occur at damage location for crane frame with reduction in stiffness ratio in (a) and (b) for single damage scenario and its observed that the peak became larger when the damage ratio 20% in case 2 which is the location of damage. (c) , (d) and (e) shows the damage location for single crack, as expected, the error are larger in case 4 damage, since this correspond to a larger crack depth for the same cross section for the three modes. when two cracks are induced in the vertical column in crane frame (damage scenarios case 5 and case 6), the proposed method is capable of detecting the location of the two cracks, as evidenced by the peaks as shown in (f) , (g) and (h) and its also the peak became bigger for crack ratio a/h = 0.2 in case 6. for the cases 5 and 6 when the two cracks induced, the peak which is near the fixed end is bigger than the other one which is far away from the fixed end and this because the maximum bending in the fixed end. from the results above, the residual error method is a good method to detect the location of the damage especially for multiple damage case compared with other methods failed to detect the multiple damage for frames or for simple beam like the damage detection from changes in curvature mode shapes method in [3]. as in fig.5 the curvature at a point of an element with bending deformation, is given by: ei m " in which " is the curvature at a section, m is the bending moment at a section, e is the modulus of elasticity and i is the second moment of the cross-sectional area. the residual error method in the movement equation is efficient in the damage location and quantification of the studied structures because the method that depend on the curvature mode shape didn’t detect the two region of damage in the first mode shape because its clear one large peak as in fig.5 (k), which detect the damage and in the second mode shape as in fig. (l), there is two peaks, one of them large and the other small but in the third one the two peaks of damage are more clear than the second as in the fig (m). table 3, natural frequencies of the crane frame damage scenario natural frequency (rad/sec) present undamaged mode 1 discrepancy % mode 2 discrepancy % mode 3 discrepancy % mode 4 discrepancy % mode 5 discrepancy % 54.6114 0 221.336 0 644.429 0 1.5358*103 0 1.7672*103 0 case 1 54.5540 0.105 221.252 0.037 643.238 0.184 1.5353*103 0.032 1.7657*103 0.084 case 2 54.4824 0.236 221.147 0.085 641.767 0.413 1.5346*103 0.078 1.7638*103 0.192 case 3 54.4999 0.204 221.019 0.143 642.151 0.353 1.5124*103 1.523 1.6916*103 4.277 case 4 54.2499 0.661 220.464 0.393 636.371 1.25 1.5017*103 2.22 1.6737*103 5.29 case 5 54.2258 0.706 220.401 0.422 641.264 0.491 1.4576*103 5.09 1.6284*103 7.854 case 6 53.2267 2.535 218.413 1.32 633.918 1.631 1.4189*103 7.611 1.6053*103 9.16 nabil h. hadi al-khwarizmi engineering journal, vol. 5, no. 4, pp 58-68 (2009) 64 (a) (b) (c) (d) (e) (f) (g) (h) fig.4. residual error method for the two and three modes of the crane frame. nabil h. hadi al-khwarizmi engineering journal, vol. 5, no. 4, pp 58-68 (2009) 65 (k) (l) (m) fig.5. absolute difference curvature mode shape method for crane frame for the first, second and third mode. 7. conclusion the main conclusions from the present work according to the adopted data may be stated as follows: 1based on assumption that the damage will change the stiffness reduction only and the mass of the beam be consistent, the increased severity of the damage will decrease the frequencies of the damaged beam. 2it’s observed that, the damage representation as stiffness reduction 20% is not equal to the damage represented by crack ratio 20%, accordingly it is obvious that the crack is more sensitive than stiffness reduction in representing the damage. 3changes on natural frequencies give the indication of damage but it can’t detect the location of the damage. 4the residual error method performs well in detecting, locating and quantifying the damage in single and multiple damage scenarios. 5the residual error increased in value with the increasing of the damage ratio. 6the residual error peak is batter clear when it’s near the region with maximum bending moment. nomenclature )0(w the strain energy of undamaged element. e elastic modulus i moment of inertia of undamaged element. l length of the finite element p internal shear force at the right end of beam. m internal bending moment at the right end of beam. iipipim kkk ,, stress intensity factors for opening-type and sliding mode cracks due to m and p  ck the stiffness matrix of the cracked element _ m the mass per unit length a the depth of the crack  c the total flexibility matrix for the element with an open crack  the poisson's ratio i the stress for the corresponding fracture mode ac the area of the crack surface nabil h. hadi al-khwarizmi engineering journal, vol. 5, no. 4, pp 58-68 (2009) 66  uk the stiffness matrix of undamaged element j the strain energy release rate  um the mass matrix for an element without crack k stiffness matrix of t he system m mass matrix of the system.  x mode shape vector evp eigen value problem algorithm uk stiffness matrix of undamaged beam um mass matrix of the undamaged beam  x damaged mode shape vector ][  diagonal natural frequencies re a vector corresponding to one mode shape and each value of this vector represents the residual error 8. references [1] ren, w. x. and de roeck, g. (2002). “structural damage identification using modal data. i.: simulation verification”. asce. journal of structural engineering, vol. 128, no. 1 january, 87-95. [2] black, p., (1966). “strength of materials” /first edition. [3] dewen, b. e, m.e. (2004). “damage detection in mechanical structures through coupled response measurements”. a thesis submitted in partial fulfillment of the requirements for the degree of doctor of philosophy in mechanical engineering /university of queensland, brisbane, australia. [4] herrera, j. c., (2005). “evaluation of structural damage identification methods based on dynamic characteristics”. a thesis submitted in partial fulfillment of the requirements for the degree of doctor of philosophy in civil engineering / university of puerto rico. [5] dinkler, (2004). “damage detection in structures using a parameter identification method ”. 2nd european workshop on structural health monitoring. july 7-9, 2004, amazeum conference centre at deutsches museummunich, germany. [6] barasiliano a., doz g.n. and brito j.l., (2003). “damage identification in continuous beams and frame structures using the residual error method in the movement equation”. nuclear engineering and design 227, 1-17. [7] qian, g.l. and jiang, j.s., (1990) “the dynamic behavior and crack detection of a beam with a crack”. journal of sound and vibration, vol.138, no. 2, 233-243. [8] kisa, m. and brandon, j., (2000). “the effect of cracks on the dynamics of a cracked cantilever beam”. available online at http:// www.idealibrary.com on ideal, cardiff, england. academic press. [9] singor l., f., (1951). “strength of materials”. second edition (book). [10] merovitch l., (1975). “elements of vibrations analysis”, (book) international student edition. [11] hellan, k., (1984). “introduction to fracture mechanics”, (book). university of trondheim /norway. printed in usa http://www.idealibrary.com/ nabil h. hadi al-khwarizmi engineering journal, vol. 5, no. 4, pp 58-68 (2009) 67 appendix a : stiffness matrix of cracked element 2 2 2311 12 12  ieabel eie k p p   2 2 2312 12 6  ieabel liee k p p   2 2 2313 12 12  ieabel eie k p p   = 11k 2 2 2314 12 6  ieabel liee k p p   1221 kk  22k )12()36( )327( 4 2 2 2322 1 2 2 222 1 23   ieabelieabel eeiieableiabel pp pp   2 2 2323 12 6  ieabel liee k p p   )12()36( )654( 2 2 2 2322 1 2 2 222 1 23 24   ieabelieabel eeiieableiabel k pp pp    1331 kk  12k 2332 kk  33k 2 2 2311 12 12  ieabel eie k p p   2 2 2334 12 6  ieabel liee k p p   14k 1441 kk  2442 kk  3443 kk  14k )12()36( )327( 4 2 2 2322 1 2 2 222 1 23 44   ieabelieabel eeiieableiabel k pp pp    22k therefore:  ck                 22142414 14111211 24122212 14111211 kkkk kkkk kkkk kkkk ...(30) 68 -58، صفحة 4، انعذد 5 مجهة انخوارزمي انهنذسية انمجهذ نبيم حسن هادي (200 9) 68 مراقبة انصحة في انهيكم انرافعة بإستعمال طريقة انخطٔا انمتبقي عبذهللا راشذ نبيم حسن هادي اقبال جاهعت بغذاد/ كلٍت الٌِذست /قسن الٌِذست الٌٌّْت انخالصة الضشس قٍن بخخفٍض هخاًَ العٌاصش الوفخشضت ّرلك بٌسبت . فً ُزا البحث حن دساست الٍِكل البابً باسخخذام طشٌقت العٌصش الوحذد إّى . العخبت الوشقْقت الوسخخذهت راث شق ّاحذ بالحافت بذّى حقذم للشق. فً ّسظ العخبت العوْدٌَ فً الٍِكل الشافعت % 20ّ % 10 ٌخوثل بسخت حاالث فً الٍِكل الشافعت ّكزلك ٌخوثل عي طشٌق شق عوْدي فً العٌاصش الوفخشضت فً الوْاقع الوخخلفت (damage)الضشس لخوثٍل الوحاكاة 5،6matlabحن اسخخذام بشًاهج . لٌفس العخبت فً الٍِكل الشافعت0,10ّ0,20 (a/h)بٌسبت عوق الشّق إلى إسحفاع العخبَ حعطً . اظِشث الٌخائج ًقص فً الخشدداث الطبٍعٍت الخوست ًسبَ للعخبَ السلٍوَ ّ الزي ُْ إشاسة لْجْد الضشس. العذدٌت لسٌٍٍُْاث الضشس الطشٌقت الوحذدٍ الٌجاد الضشس الخً حن اسخخذاهِا ًُ هسخٌذة على . الوقاسًت الوباششة إشاسة الى ّجْد الضشس لكي هْقع الضشس غٍش هحذد ًخائج الخحلٍل حشٍش إلى اى طشٌقت الخطأ الوخبقً . الخغٍٍشاث فً خصائص دٌٌاهٍكت حشاكٍب العخبت ّ الطشٌقت فحصج ّقٍّوج حاالث الضشس residual errorحعول بصْسة جٍذة فً إكخشاف ّححذٌذ هكاى الضشس فً سٌٍاسٌُْاث الضشس damage scenarios الْحٍذة الوْقع .ّالوخعّذد الوْاقع 108 al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 4, no. 3, pp 108-119 (2008) comparison study of electromyography using wavelet and neural network nebras hussain gheab* sadeem nabeel saleem** baghdad university/ al khwarizmy college of engineering/ biomedical engineering department *email: nbmeng@yahoo.com **email: sedeemkubba@gmail.com (received 5 march 2008; accepted 17 july 2008) abstract in this paper we present a method to analyze five types with fifteen wavelet families for eighteen different emg signals. a comparison study is also given to show performance of various families after modifying the results with back propagation neural network. this is actually will help the researchers with the first step of emg analysis. huge sets of results (more than 100 sets) are proposed and then classified to be discussed and reach the final. keywords: emg, wavelet transform, neural network, back propagation. 1. introduction electromyography is the discipline that deals with the detection, analysis, and use of the electrical signal that emanates from contracting muscles. this signal is referred to as the electromyography (emg) signal. an example of the emg signal can be seen in fig. 1. here the signal begins with a low amplitude, which when expanded reveals the individual action potentials associated with the contractile activity of individual (or a small group) of muscle fibers. as the force output of the muscle contraction increases, more muscle fibers are activated and the firing rate of the fibers increases. correspondingly, the amplitude of the signal increases taking on the appearance and characteristics of a gaussian distributed variable [1]. fig. 1. the emg signal recorded with surface electrodes located on the skin above the first dorsal interosseous muscle in the hand. the signal increases in amplitude as the force produced by the muscle increases. the nervous system always controls the muscle activity (contraction/ relaxation). hence, the emg signal is a complicated signal, which is controlled by the nervous system and is dependent on the anatomical and physiological properties of muscles. emg signal acquires noise while traveling through different tissues. moreover, the emg detector, particularly if it is at the surface of the skin, collects signals from different motor units at a time, which may generate interaction of different signals [2]. detection of emg signals with powerful and advance methodologies is becoming a very important requirement in biomedical engineering. mailto:nbmeng@yahoo.com mailto:sedeemkubba@gmail.com nebras hussain gheab al-khwarizmi engineering journal, vol. 4, no. 3, pp 108-119 (2008) 109 the main reason for the interest in emg besides basic physiological and biomechanical studies, kinesiological emg is established as an evaluation tool for applied research, physiotherapy/ rehabilitation, sports training and interactions of the human body to industrial products and work conditions, fig. 2 explain the wide spread use of emg signal [3]: fig. 2. the emg aspects. however, a number of problems are associated with the recording and the analysis of the transient emg signal. a main problem is due to the noisy character of the signal. the noisy character is due to the fact that several muscle activations that occur simultaneously are recorded from the electrode(s) that are attached to the skin. what is actually being recorded is the superposition of several muscle activations filtered through different transfer paths of the surrounding tissues and the skin itself [4]. emg signals are nonstationary and have highly complex time–frequency characteristics. consequently, these signals cannot be analyzed using classical methods such as fourier transform. although the short time fourier transform can be used to satisfy the stationarity condition for such nonstationary signals, it suffers from the fact that the performance depends on choosing an appropriate length of the desired segment of the signal. to overcome such problem, wavelet transform has been widely used in signal analysis [5]. an important requirement in this area is to accurately classify different emg patterns for controlling a prosthetic device. for this reason, effective feature extraction is a crucial step to improve the accuracy of pattern classification; therefore, many signal representations have been suggested. the wavelet transform have been successfully applied with promising results in emg pattern recognition by englehart and others (1998). the discrete wavelet transform (dwt) and its generalization, the wavelet packet transform (wpt), were elaborated in (englehart 1989a). these techniques have shown better performance than the others in this area because of its multilevel decomposition with variable trade-off in time and frequency resolution. the wpt generates a full decomposition tree in the transform space in which different wavelet bases can be considered to represent the signal. the techniques were applied to feature extraction from surface emg signals. amount of coefficients, since the transform space has very large dimension. this fact suggests the systematic application of feature selection or projection methods and dimensionality reduction techniques to enable the methodology for real time applications [6]. this paper continues the work described above by taking different families of wavelet transform and studies the coefficients of them after passing the training and validate in the neural network. 2. the raw emg signal an unfiltered (exception: amplifier band pass) and unprocessed signal detecting the superposed multi unit action potentials (muap) is called a raw emg signal. as given below (fig. 3), a raw surface emg recording (semg) was done for three static contractions of the biceps brachii muscle: nebras hussain gheab al-khwarizmi engineering journal, vol. 4, no. 3, pp 108-119 (2008) 110 fig. 3. the raw emg recording of three contractions the muscle biceps brachii [2]. when the muscle is relaxed, a more or less noise–free emg baseline can be seen. the raw emg baseline noise depends on many factors, especially the quality of the emg amplifier, the environment noise and the quality of the given detection condition. assuming a state-of-the-art amplifier performance and proper skin preparation, the averaged baseline noise should not be higher than 3 – 5 microvolts, 1 to 2 should be the target. the investigation of the emg baseline quality is a very important checkpoint of every emg measurement. the healthy relaxed muscle shows no significant emg activity due to lack of depolarization and action potentials! by its nature, raw emg spikes are of random shape, which means one raw recording burst cannot be precisely reproduced in exact shape. this is due to the fact that the actual set of recruited motor units constantly changes within the matrix / diameter of available motor units: if occasionally two or more motor units fire at the same time and they are located near the electrodes, they produce a strong superposition spike! by applying a smoothing algorithm (e.g. moving average) or selecting a proper amplitude parameter (e.g. area under the rectified curve), the nonreproducible contents of the signal is eliminated or at least minimized. raw semg can range between +/-5000 microvolts and typically, the frequency contents ranges between 6 and 500 hz, showing most frequency power between ~20 and 150 hz [3]. 3. factors influencing the emg signal on its way from the muscle membrane up to the electrodes, the emg signal can be influenced by several external factors altering its shape and characteristics. they can be grouped in [3]: a. tissue characteristics. the human body is a good electrical conductor, but unfortunately, the electrical conductivity varies with tissue type, thickness (fig. 4), physiological changes and temperature. these conditions can greatly vary from subject to subject (and even within subject) and prohibit a direct quantitative comparison of emg amplitude parameters calculated on the unprocessed emg signal. fig. 4. the influence of varying thickness of tissue layers below the electrodes [2]. b. physiological cross talk. neighboring muscles may produce a significant amount of emg that is detected by the local electrode site. typically this “cross talk” does not exceed 10%-15% of the overall signal contents or is not available at all. however, care must been taken for narrow arrangements within muscle groups. ecg spikes can interfere with the emg recording, especially when performed on the upper trunk / shoulder muscles. they are easy to see and new algorithms are developed to eliminate them. c. changes in the geometry between muscle belly and electrode site. d. external noise. e. electrode and amplifiers. 4. emg signal processing raw emg offers us valuable information in a particularly useless form. this information is useful only if it can be quantified. various signalprocessing methods are applied on raw emg to achieve the accurate and actual emg signal. reza time, s µv nebras hussain gheab al-khwarizmi engineering journal, vol. 4, no. 3, pp 108-119 (2008) 111 et al. [2] discussed the major emg signal processing methods used currently. 5. wavelets wavelets are building blocks for general functions. that means that any general function can be expressed as an infinite series of wavelets. the basic idea underlying wavelet analysis consists of expressing a signal as a linear combination of a particular set of functions, obtained by shifting and dilating one single function called a mother wavelet. several different mother wavelets have been studied in daubechies [7] and meyer [8]. the decomposition of the signal into the basis of wavelet functions implies the computation of the inner products between the signal and the basis functions, leading to a set of coefficients called wavelet coefficients. the signal can consequently be reconstructed as a linear combination of the basis functions weighted by the wavelet coefficients. in order to obtain an accurate reconstruction of the signal, a sufficient number of coefficients have to be computed. the procedure followed for calculating the wavelet coefficients is shown graphically in fig. 5. the main characteristic of wavelets is the timefrequency localization. in effect, that means that most of the energy of the wavelet is restricted to a finite time interval. frequency localization means that the fourier transform is band limited. the advantage of time – frequency localization is that contrary to the short time fourier transforms a wavelet analysis varies the time frequency aspect ratio, producing good frequency localization at low frequencies (long time windows), and good time localization at high frequencies (short time windows). this produces segmentation, or tiling of the time-frequency plane that is appropriate for most physical signals, especially those of a transient nature. the difference between the short time fourier transform and the wavelet transform is illustrated in fig. 6 [4]. fig. 5. the operations of shifting and dilation of the mother wavelet to calculate the w. coefficients [4]. fig. 6. the tiling of the time-frequency plane in the case of short-time fourier transform (stft) and discrete wavelet transform (dwt) respectively. 6. wavelet techniques for emg: a lot of papers and researches have been written to discuss the different applications for the wavelet techniques in biosignal and emg specifically. we briefly consider the application of wavelet systems from two perspectives [9]: first: we look at the wavelets as a tool for denoising and compressing an emg signal (more details see [4, 10, 11]), where noise removing process, and compression for biotelemetry techniques. second: we look at the wavelet as a tool for feature extraction and classification (more details see [5, 6, 12]), where the process of defining the movement and control for the prosthetic applications are desired. nebras hussain gheab al-khwarizmi engineering journal, vol. 4, no. 3, pp 108-119 (2008) 112 7. application of neural network back propagation algorithm solving emg signal with the artificial neural network (ann) techniques have been reported with different powerful strategies, for the present application, back propagation is used to train the feed forward nn [13], see fig. (7). fig. 7, back propagation nn. during the training phase, each output neuron (zi) compares its computed activation with its target value (ti) to determine the associated error (ei) for the neuron, where: e = ∑ (zi ti) 2 …(1) the ann weights and biases are adjusted to minimize the least square error. 8. wavelet types and families: there are different types of wavelet families whose qualities vary according to several criteria. the main criteria are [14]: a. the support of ψ, φ: the speed of convergence to zero of these functions ψ(t) when the time t or the frequency ω goes to infinity, which quantifies both time and frequency localizations. b. the signal symmetry. c. the number of vanishing moments for ψ or φ for (if it exists), which is useful for compression purposes. d. the regularity, which is useful for getting nice features, like smoothness of the reconstructed signal, and for the estimated function in nonlinear regression analysis. the wavelet types included in our work here can be classified to the following groups [14]: 1. crude wavelets. a. wavelet families: gaussian, morlet, mexican hat. b. properties: only minimal properties: φ does not exist. the analysis is not orthogonal. ψ is not compactly supported. the reconstruction property is not insured. c. possible analysis: continuous decomposition. d. main nice properties: symmetry, ψ has explicit expression. e. main difficulties: fast algorithm and reconstruction unavailable. 2. infinitely regular wavelets: a. wavelets families: meyer. discrete meyer wavelet. b. properties: φ exists and the analysis is orthogonal. ψ and φ are indefinitely derivable. ψ and φ are not compactly supported. c. possible analysis : continuos transform. discrete transform but with non-fir filters. d. main nice properties: symmetry, infinite regularity. f. main difficulties: fast algorithm unavailable. 3. orthogonal and compactly supported wavelets. a. wavelets families: daubechies, symlets, coiflets. b. general properties: φ exists and the analysis is orthogonal. ψ and φ are compactly supported. ψ given number of vanishing moments. c. possible analysis: continuous transform. discrete transform using fwt. d. main nice properties: support, vanishing moments, fir filters. e. main difficulties: poor regularity. 4. biorthogonal and compactly supported wavelet pairs. a. wavelets families: b-splines biorthogonal wavelets. b. properties: φ functions and analysis is biorthogonal. ψ and φ both for decomposition and reconstruction are compactly supported. φ and ψ for decomposition have vanishing moments. ψ and φ for reconstruction have known regularity. c. possible analysis: continuous transform. discrete transform using fwt. nebras hussain gheab al-khwarizmi engineering journal, vol. 4, no. 3, pp 108-119 (2008) 113 d. main nice properties: symmetry with fir filters, desirable properties for decomposition and reconstruction are split and nice allocation is possible. e. main difficulties: orthogonality is lost. 5. complex wavelets. a. wavelets families: complex gaussian, complex morlet, complex shannon, complex frequency bspline. b. properties: only minimal properties φ does not exist. the analysis is not orthogonal. ψ is not compactly supported. the reconstruction property is not insured. c. possible analysis: complex continuos decomposition. d. main nice properties: symmetry, ψ has explicit expression. e. main difficulties: fast algorithm and reconstruction unavailable. table (1) below represent the whole fifteen wavelet families with their short name as expressed in matlab 7.a, at the same time table (2) a and b, represent the summery for the properties of the fifteen wavelet families with their properties. table 1 wavelet families with their abbreviations [14]. nebras hussain gheab al-khwarizmi engineering journal, vol. 4, no. 3, pp 108-119 (2008) 114 table 2 properties of the wavelet families [14]. nebras hussain gheab al-khwarizmi engineering journal, vol. 4, no. 3, pp 108-119 (2008) 115 9. material and method we developed a preliminary version for the whole families in matlab, and as experimenting values for the emgs we test 2 cases of butterfly exercises one with 5 lb and the other with 10 lb. for each one of the two cases we took three different volunteers with three different muscles locations for each one of them, right pectoralis, right biceps and right triceps. in total we have got 18 (eighteen) data files with sampling frequency 2000 hz [15], with 4000 samples length for each file. the analysis of these data files started with converting them to .mat files and then removes any dc offset to be ready for the wavelet families’ analysis. in this stage each family were considered as special solution for the proposed case, and of course the output of the wavelet family are the coefficients and details which will be trained with the back propagation neural network, the reason for this training to get finally the error proposed in each analysis. comparison finally between the sets of errors will help us with the final. 10. results huge sets of results have been found here, table (3) explained that 1350 runs, so for explanation of the results, we will explain and discuss samples of them and for more information, you visit my web in www.biomedicaleng2006.jeeran.com. (results will be uploaded to the website after the date of acceptance). table 3 number of runs. no. of cases 2 no. of volunteers 3 no. of measured points 3 no. of families 15 no. of level for each family (at least) 5 total number of runs 1350 figures 8 (a, b and c) shows the emg signals for 5lb first person (expressed as 5_1), of course these signals have been plotted after the dc offset have been removed. (a) pectoralis of 5 lb with volunteer 1. (b) biceps of 5 lb with volunteer 1. (c) triceps of 5 lb with volunteer 1. fig. 8. emg for 5_1. the continuous with the analysis shows in figures 9 the db4 for pect5_1 where the technique used here is dwt. the output decomposed (denoised) signal are treated with the back propagation nn in which we considered the input to this net is (s = a4 + d4 + d3 + d2 + d1) and the target is the original signal (so as to found out the residuals), the training is 60% (these are presented to the network during training, and the network is adjusted according to its error) of the original samples (2400 samples of 4000), validation 20% (these are used to measure network generalization, and to halt training when generalization stops improving) of the original http://www.biomedicaleng2006.jeeran.com/ nebras hussain gheab al-khwarizmi engineering journal, vol. 4, no. 3, pp 108-119 (2008) 116 samples (800 samples of 4000) and the testing 20% (these have no effect on training and so provide an independent measure of network performance during and after training) of the original samples (800 samples of 4000), with 20 hidden neurons. table (4) proposed the final results for the ann after running the nn for 20 epochs. fig. 9. db4 for pectoralis 5_1. table 4 results of nn for pectoralis 5_1 of db4. where mse: is the mean squared error is the average squared difference between (normalized) outputs and targets. zero means no error, over 0.6667 means high error. and r: regression values measure the correlation between (unnormalized) outputs and targets. an r value of 1 means a close relationship, 0 a random relationship. at the same fig. 10 shows the performance, epochs relations for the training, validation and test. we can observe in most of the families that we have tested before that the level of the wavelet is very important for the training and performance of the nn, level 4 and 5 in db and haar are closest in results than the other highest or lowest level. while the other families recorded unstable response in levels with the action analysis and effect in the nn performances. nebras hussain gheab al-khwarizmi engineering journal, vol. 4, no. 3, pp 108-119 (2008) 117 fig. 10. epochs – performance relationship for the training, validation and test of pectoralis 5_1 of db4. 11. conclusions in this paper, we have checked most of the families used to process the emg signals into denoising and compressing. our target is to reach a high quality of the performance for combined wavelet techniques with the ann. the obtained results are very huge to be discussing in one paper but they are comfortable and reach a final decision. our approach uses a two parts the first wt technique and the second ann, where the first used to generate deniosed signal (or compressed) and the second used to train this signal and calculate its performance of training and validation the results indicate that, haar and db in their (4 th to 5 th level) are more comfortable to use with our samples of emg. 12. references [1] john g. webster, encyclopedia of medical devices and instrumentation, 2 nd edition, 2006, vol. 3, p 99 – 109. [2] m. b. i. reaz, m. s. hussain and f. mohdyasin, techniques of emg signal analysis: detection, processing, classification and applications, biol. proced. online 2006 8(1): 11-35. [3] peter konrad, the abc of emg a practical introduction to kinesiological emg, power by noraxon inc. usa, version 1.0 april 2005, page 5. [4] d. moshou, i. hostens, g. papaioannou, h. ramon, wavelets and self-organizing maps in emg analysis, esit 2000, 14-15 september 2000, aachen, germany. [5] k. englehart, b. hudgins, p. a. parker and v. stevenson (1999). classification of the myoelectric signal using time-frequency based representations, medical eng. and physics, volume 21, pages 431-438. nebras hussain gheab al-khwarizmi engineering journal, vol. 4, no. 3, pp 108-119 (2008) 118 [6] r. carreño and m. i. vuskovic: “wavelet transform moments for feature extraction from temporal signals’” 2 nd internat. conference in control, automation and robotics (icinco 2005), 14-17 september, barcelona, spain, 2005 [7] daubechies, i., 1988, “orthonormal bases of compactly supported wavelets”, commune. pure applied mathematics 41, pp. 909-996. [8] meyer, y., 1989, “orthonormal wavelets, wavelets, time-frequency methods and phasespace”, j. m. combes, a. grossman, p. tchamitchian, (eds.), springer-verlag, pp. 2137. [9] c. s. burrus, r. a. gopinath, and h. guo, introduction to wavelet and wavelet transforms, prentice – hall, inc., 1998. [10] p. wellig, c. zhenlan, m. semling, and g. s. moschytz, “electromyogram data compression using single-tree and modified zero-tree wavelet encoding,” in engineering in medicine and biology society. proceedings of the 20th annual international conference of the ieee, hong kong, china, oct. 1998, vol. 3, pp. 1303– 1306. [11] m. s. hussain, m. b.i. reaz, m. i. ibrahimy, and f. mohd-yasin, an efficient technique of analyzing surface emg signals, isbme 2006, paper no. 107. [12] j. u. chu, i. moon, and m mun, a realtime emg pattern recognition based on linear-nonlinear feature projection for multifunction myoelectric hand, proceedings of the 2005 ieee, 9th international conference on rehabilitation robotics, june 28 july 1, 2005, chicago, il, usa. [13] j. laakso, m. juhola, v. surakka, a. aula and t. partala, neural network and wavelet recognition of facial electromyographic signals, medinfo, v. patel et al. (eds), amsterdam: ios press, 2001. [14] wavelet toolbox help, matlab 7.a. [15] g. d. luca, fundamental concepts in emg signal acquisition, delsys inc., 2003. nebras hussain gheab al-khwarizmi engineering journal, vol. 4, no. 3, pp 108-119 (2008) 119 دراست هقارنت الشارة التخطيط العضلي باستخذام الوويجت و الشبكاث العصبيت نبراس حسين غائب سذين نبيل سلين جايؼح تغذاد / كهيح هنذسح انخىاسيي/ قسى هنذسح انطة انحياتي الخالصت انذراسح . ػضهيح يختهفحنثًانيح ػشز اشارجقذينا طزيقح نتحهيم خًس انىاع نخًسح ػشز يجًىػح ين يجاييغ انًىيجح , في هذا انثحث هذا سىف يساػذ انثاحثين . انًقارنح تظهز ايضا اداء انًجاييغ انًحتهفح تؼذ يؼانجح و تحىيز اننتائج تاسهىب االرجاع انؼكسي نهشثكاخ انؼصثيح .كى هائم ين اننتائج تقذو و تصنف نهًناقشح و انىصىل انى نتائج. في انخطىج االونى نتحهيم االشارج انؼضهيح ammar a. hassan /al-khwarizmi engineering journal ,vol.3, no. 1 pp, 80-41 (2007) ١ reduction of the error in the hardware neural network dr. dhafer r. zaghar computer and programming engineering department college of engineeringal-mustanserya university / baghdad/ iraq (received 7 march 2006; accepted 24 april 2007) abstract:specialized hardware implementations of artificial neural networks (anns) can offer faster execution than general-purpose microprocessors by taking advantage of reusable modules, parallel processes and specialized computational components. modern high-density field programmable gate arrays (fpgas) offer the required flexibility and fast design-to-implementation time with the possibility of exploiting highly parallel computations like those required by anns in hardware. the bounded width of the data in fpga anns will add an additional error to the result of the output. this paper derives the equations of the additional error value that generate from bounded width of the data and proposed a method to reduce the effect of the error to give an optimal result in the output with a low cost. key words: neural, co-processor, dsp, fpga, ise 4.1i software, adder, multiplier. 1.introduction artificial neural networks have for many years proved themselves effective tools in classification and even prediction of arrays of patterns. today, artificial neural networks are used in diverse applications, ranging from voice recognition to weather prediction models [1,2]. as industry has developed the need for rapid prototyping and denser devices, fpga have become excellent tools for the implementation of complex digital systems [3,4]. by taking advantage of the dynamic flexibility that fpgas have to offer, a digital implementation of a general-purpose ann in the form of a coprocessor is created and presented in this paper. this ann co-processor has been designed to work in conjunction with a dsp or generalpurpose processor to create a fast and flexible intelligent ann system with the potential to be used in a wide range of applications. by realizing specific hardware entities commonly used in anns like multiplication and addition and exploiting any parallelism found in the net, the hardware implementation of an ann can very well outperform its software counterpart when comparing the throughput of both methods. one, nevertheless, has to keep in mind that the use of fpgas implies the sacrifice of flexibility for speed. while the fpga we use has a relatively large quantity of resources, we make a conscious effort to improve speed while keeping the gate count to a minimum. for this reason, each layer in the ann is composed of parallel neurons that individually compute a summation of products, and all the internal components of the network are designed to take advantage of the al-khwarizmi engineering journal al-khwarizmi engineering journal, vol.3, no.2, pp1-7 (2007) this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. dhafer r. zaghar /al-khwarizmi engineering journal, vol.3, no.2 pp1-7 (2007) available hardware resources like fast-carry chains, lookup tables and distributed ram blocks [5]. 2. hidden and output layer design the target device for the co-processor design is xilinx’s spartan ii fpga. this device is chosen because of its distributed memory ram banks which allow implementation of fast register files where inputs and weights are stored, its versatile i/o interface that supports 3.3v outputs and ttl voltage levels and its low market cost. the complete co-processor design is written in vhdl (vhsic hardware description language and the acronym vhsic, in turn, refers to the very high-speed integrated circuit program) using a structural approach with the help of xilinx foundation series ise 4.1i software [6]. the hardware implementation of the neurons realizes the following two equations: 1210 1 0 ,....m-,, jxwa i n i s ij s j     ... (1) )f( ao s j s j  …..... (2) wherea s j in (1) is the jth-accumulated sum for layer s with m neurons and n inputs, w s ij is the weight between node i in layer s-1 and node j in layer s, xi is the ith input and o s j in (2) is the output of the jth neuron of layer s given by the activation function [5]. 3.hardware neural node the corresponding block diagram in fig.(1) is a single neuron that has n input data and n input weight each one has k-bit bus width. the calculation of the output pass in to two stages first is the multiplication then second is the accumulation of the result of the multiplication stage. the multiplication stage has n multiplier each multiplier has two inputs with k-bit one for the data and the other for weight. each multiplier give 2k-bit output but the next stage has k-bit input, therefore the output must be truncated to k-bit. this truncation represents a positive error in the range 20 -k to that has average value equal to 2 1-k . the accumulation stage has m layer that can be calculated from equation (3), each one ( ith layer) will have 2 im  adder unit. log 2 n* m  …………………………..(3) where n* is the nearest maximum power of 2 number to n and n is the number of input data buses in neuron. each adder unit in the layers of the accumulation stage has two k-bit inputs with single output that has (k+1)-bit but the next layer is design to k-bit input, therefore the output must be truncated to k-bit. this truncation represents a positive error in the range 2 1 0 -k to that has average value equal to 2 2-k [7, 8]. however, the average value of the error in each layer ei calculated from equation (4) and the total average error in accumulation stage calculated ea from equation (5) below. 222 2 tm-i-ki * e  … (4) 2m-k-iwhere t  2 2 1 1 -km i m-i i a m*ee    …... (5) the total error in the neuron en is the sum of the multiplication stage and the accumulation stage with the effect of truncation in the next stage to the error of the past stage as in equation (6). this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. dhafer r. zaghar /al-khwarizmi engineering journal, vol.3, no.2 pp1-7 (2007) ) (m m* n * * ee -k--k--kam -kn 222 2 2 111 1 1 ……. (6) the result of error in output in range from 210 -k ) to (m  with positive average equal to 2 1 1  -k ) (m and the mean square error (mse) equal to 21 322  k-)(m however, the number of data inputs in ann is varied from 5 to 1000, that is mean the value of m is varied generally between 3 to 10 and it can be writen as: 4. reduction of the error there are three suggestion steps to reduce the total error in the output of the hardware neuron as follows: 1expanded data bus in the internally layers of the accumulation stage and make all the truncation in the last layer. that means if the first layer has k-bit the second layer will have (k+1)-bit and the ith layer will have (k+i1)-bit and so on until to the last (m) layer that will truncate the data to the original data bus kbit. this process will reduce the error in the accumulation stage to range 20 -k to that has average value equal to 2 1-k . that means that the total error output is in range 20 -k to with positive average equal to 2 1-k and mse equal to 2 32 k. 2add a round unit to the multipliers of the multiplication unit as shown in fig. (2).the round unit sums up the truncated values of each two-neighbor multiplier then approximate the kxk bit multiplier 1 kxk bit multiplier 2 kxk bit multiplier n-1 kxk bit multiplier n k+k bit adder n/2 k+k bit adder 1 k+k bit adder 1 multiplication stage first adder layer last m adder layer fig. (1): block diagram for implementing a single neuron. .2 v m  this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. dhafer r. zaghar /al-khwarizmi engineering journal, vol.3, no.2 pp1-7 (2007) result to the lsb value. hence, if this value is greater than the half of the lsb it will add to the accumulator else it will neglect if it is smaller than the half of the lsb. this process will reducte the error in the multiplication stage to range 22 22  -kk to that has average value equal to zero and mse equal to 2 42 k. 3add a round unit to the last layer of the accumulation as shown in fig. (3). the round unit approximates the truncated value to the lsb value if this value is greater than half of the lsb and neglected the truncated value if it is smaller than half of the lsb. this process will reduce the error in the multiplication stage to range 22 22  -kk to that has average value equal to zero and mse equal to 2 42 k. the total error of the neuron output after applying the three steps is in range 22 11  -kk to that has average value equal to zero and mse equal to 2 22 k. k msbs k lsbs neglect k msbs k lsbs neglect k+k bit adder kxk bit mult. kxk bit mult. a b k msbs k lsbs k msbs k lsbs k+k bit adder kxk bit mult. kxk bit mult. round unit carry input fig.(2): block diagram for multiplier and the first layer in accumulation unit in neuron (a) original and (b) after step 2. k msbs output m+1 lsbs neglect (k+m)+(k+m) bit adder a b round unit carry input k msbs output m+1 lsbs (k+m)+(k+m) bit adder fig. (3): block diagram of the last layer in accumulation unit in neuron (a) original and (b) after step 1 and step3 this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. dhafer r. zaghar /al-khwarizmi engineering journal, vol.3, no.2 pp1-7 (2007) 5. software implementation the proposed steps to reduce the error is tested using software simulation to implement an ann equivalent to hardware circuit of this network. at first the original ann is implemented using back propagation algorithm [9] using c++ or matlab, then it will be modified to represent the hardware ann by applying the following steps: a) define all values in the program as integers fill in rang ± (2k-1 -1). b) replace each addition process c= a+b with c= (a+b)/2. c) replace each multiplication process z= x*y by the following steps: 1convert the second number (y) to binary number (yy). 2multiply the digits of the binary number (yy) by weights that are the powers of two to calculate the set {u}. 3use shift and add (under condition b) approach [10] between the number a and {u} to satisfy the multiplication process. the simulation of step 1 in section (4) require to replace condition (b) {     1 0 )(b)condition under ( n i iac } in the original program to become     1 0 2/ n i m iac . the simulation of step 2 in section (4) require to replace condition (b in condition c3) to become c= (a+b+0.5)/2. while the simulation of step 3 in section (4) require to replace condition (b) to become c= (a+b+0.5)/2. 6. example this example discus the effect of the reduction of the error in a single neuron from the hidden layer in a neural network that has 54 nodes in input layer (m=6), 30 nodes in hidden layer and 10 nodes in output layer and use 8-bit data bus (k=8) for all nodes. the error of the output in table (1) is calculated with respect to the maximum amplitude of the input and output (maximum value equal to 1). the original error is calculated from section (3) and the other values of the error is calculated from the steps of section (4) using m=6 and k=8. the above ann is simulated using c++ program to represent an ann that is used to detect the ten digits. the learning of the original software simulation (without any truncation) gives an error 3.7%. the reuse of the original software simulation with additional function to represent the effect of the truncation as in section (5) will give an error 14.2%. the modification of the truncation function to represent the effect of the steps in section (4) will give the results in table (2). table (2) shows the practical results of the simulation of the ann in the example, this table shows that the truncation increases the total error from 3.7% to about 14.2%, while the proposed method will reduce this to 5.9%. the cost of the neuron in table (2) is calculated by the classic design of adder and multiplier in [7], while the additional cost for the steps 1, 2 and 3 must be calculated from the specific design with routes of the reference [7]. table (1): the error of the output calculates with respect to the maximum amplitude. error range *1000 average *1000 mse *10-6 original 0 to 27.34 13.67 93.46 step1 0 to 7.81 3.9 30.52 step1 with step 2 -3.9 to 5.86 1.953 24.79 step1 with step 3 -3.9 to 5.86 1.95 24.79 all steps -3.9 to 3.9 0 15.25 this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. dhafer r. zaghar /al-khwarizmi engineering journal, vol.3, no.2 pp1-7 (2007) 7. conclusion the implementation of anns in hardware has been proven to be beneficial for intelligent systems requiring fast computation of data. but the bounded width of the data in the hardware implementation will generate an error in the output of the neuron, this error will add to the result of the output as additional error. the bounded width of the data will generate an additional error value. the additional error value will fall in the range 10-4 per single process (addition) but it will represent an accumulated additional error in the result reach to about 10%. the proposed method reduces the effect of the accumulated error depend on rounding the truncated values to give an optimal result in the output. this process will reduce the accumulated additional error value from about 14% to about 6%. however, it will increase the efficiency of the output 8% with a small additional cost less than 6%. 8. references [1] christodoulou, c., s. michaelides, c. pattichis, and k. kyriakou, “classification of satellite clouds imagery based on multifeature texture analysis and neural networks,” ieee international conference on image processing, v.1. 2001, p 497-500. [2] soren, k. r., “hidden neural networks: application to speech recognition,” neural computation v.11 1999, p. 54. [3] jayaraman, r., “physical design for fpgas,” proceedings of the 2001international symposium on physical design, sonoma, ca, p 214-221. [4] dimond, k., and k. pang, “mapping vhdl descriptions of digital systems to fpgas,” iee colloquium digest: computing and control division colloquium on software support and cad techniques for fpgas (field programmable gate arrays), n 094, p 9/1-9/3, 1994. [5] contreras, g, and nava, p, “design, implementation and testing of an fpga-based neuro-coprocessor”, dept. of electrical and computer engineering, the university of texas at el paso 500 w, 2002. [6] advance product specification, “virtex-e 1.8 v field programmable gate arrays”, ds022 (v1.0) december 7, 1999. [7] hikawa, h. “implementation of simplified multilayer neural network with on-chip learning,” proc.of the ieee international conference on neural networks (part 4), vol. 4, 1999, pp 1633-1637. [8] schelin, c.w., “calculator function approximation”, am. math. monthly, vol.90, 1983. [9] max van daalen, peter jevons, and john shawe taylor. a stochastic neural architecture that exploits dynamically recon_gurable fpgas. proceedings ieee workshop on fpgas for custom computing machines, pages 202{211, april 1993. [10] oudjida, a.k., “high speed and very compact two’s complement serial/parallel multipliers using xilinx’s fpga ”, cdta/microelectronics laboratory 128 chemin mohamed gacem el-madania 16075, algiers,algeria,1996. table (2): the simulation results of the error and the fpga cost of the network method average of the percentage error fpga cost cell / neuron software 3.7 -----after truncation 14.2 14880 step1 9.6 15036 step1 with step 2 8.3 15792 step1 with step 3 8.4 15048 all steps 5.9 15804 this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. dhafer r. zaghar /al-khwarizmi engineering journal, vol.3, no.2 pp1-7 (2007) الخطأ لبناء الشبكة العصبیة مستوىتقلیل ظافر رافع زغیر. د كــلیة الھــندسـة /و البرامجیات قـسم ھـندسة الحـاسبـات الجامـعة المستنصریة : الخالصة باستخدام المكونات المادیة یكسبھا سرعة عالیة مقارنھ ) anns(ان عملیة بناء الشبكات العصبیة الذكیة ات التي تنفذ على معالج احادي مایكروي و ذلك بسبب كون البناء باستخدام المكونات المادیة یعتمد على المعالجة بالبرامجی و ) fpga(ان واحدة من احدث طرق البناء المادي المستخدمھ ھي مصفوفة البوابات الواسعة القابلة للبرمجة . المتوازیة محددات البناء باستخدام المكونات المادیة ھي كون ناقل البیانات محدد بسعة ان من . التي تتمیز بالمرونة و السرعة العالیة سیقوم ھذا البحث باشتقاق المعادالت التي تمثل نسبة . اضافة نسبة خطاء الى النتائج النھائیة معینة ثابتھ و ھذا التقیید یسبب قلیلة للحصول على نسبة خطاء قلیلة مع كلفة غیر الخطاء االضافي و تقترح طریقة مناسبھ لتقلیل ھذا الخطاء و بزیادة كلفة . عالیة this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ 1 al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 4, no. 3, pp 1-7 (2008) design and simulation of gaussianfsk transmitter in uhf band using direct modulation of σδ modulator fractional-n synthesizer ali mohammed noori hasan departement of information and communication/ al-khawarizmi college of engineering /university of baghdad (received 4 march 2008; accepted 21 july 2008) abstract this research involves design and simulation of gaussianfsk transmitter in uhf band using direct modulation of σδ fractional-n synthesizer with the following specifications: frequency range (869.9– 900.4) mhz, data rate 150kbps, channel spacing (500 khz), switching time 1 µs, & phase noise @10 khz = -85dbc. new circuit techniques have been sought to allow increased integration of radio transmitters and receivers, along with new radio architectures that take advantage of such techniques. characteristics such as low power operation, small size, and low cost have become the dominant design criteria by which these systems are judged. a direct modulation by σδ fractional-n synthesizer is proposed in this research, because this approach provides the required characteristics such as low power. the σ∆ modulator placed on digital phase-locked loop to control the fractional value of the frequency division ratio thereby eliminating spurious and allowing good phase noise performance. the modulation type of gaussian fsk is used to obtain high spectral efficiency of modulated waveform. the applications of this transmitter in low cost wireless data transfer, security systems, rf remote controls and wireless metering. keywords: mash modulator, gaussian, fractional, sigma deta and fsk. 1. introduction: the use of wireless products has been rapidly increasing the last few years, and there has been world wide development of new systems to meet the needs of this growing market. characteristics such as low power operation, small size, and low cost have become the dominant design criteria by which these systems are judged. as a result, new circuit techniques have been sought to allow increased integration of radio transmitters and receivers, along with new radio architectures that take advantage of such techniques. radio transmitters revolve around a common goal—a low frequency modulation signal must be translated to a desired rf band. since the advent of the superheterodyne design by armstrong (which dates back to 1918 [1]), the majority of high performance, narrowband transmitters have accomplished this frequency translation using mixers and an intermediate frequency (if) region of operation to perform highly-selective filtering. while such an approach offers excellent radio performance (low spurious noise for transmitters), it carries with it a high cost of implementation in light of efforts to integrate radio architectures. specifically, this approach is impeded by the inability to integrate the high-q, low-noise, lowdistortion bandpass filters required at if frequencies (often on the order of 70 to 100 mhz for 900 mhz systems). for the above reasons, research into non-heterodyne architectures has taken place over the last few years in response to the growing demand for portable communication devices. indeed, the use of direct carrier modulation has now become widespread in a transmitter [1], which allows the channel shaping filters to be implemented at baseband and thus be integrated. ali mohammed noori hasan al-khwarizmi engineering journal, vol. 4, no. 3, pp 1-7 (2008) 2 2. modulator architectures: of the new designs, the one that appears most promising in terms of power consumption involves the direct modulation of a vco. figure (1) displays the basic operations that are used to perform frequency translation in the above designs. the prevalent method, shown in part (a), is to use a mixer to multiply the modulation signal by a periodic waveform produced by a voltage controlled oscillator (vco) whose frequency is precisely set through the action of a frequency synthesizer. in the case of direct conversion, the modulation waveform is an analog signal composed of i and q channels which are directly translated from baseband to the desired rf frequency and then added together. the superheterodyne approach uses at least two stages of mixers to accomplish the frequency translation so that an intermediate filtering stage can be employed. as discussed above, the direct conversion method is preferred to achieve high integration. however, it should be noted that this method requires two mixers and d/a converters to accommodate the i and q channels. fig. 1. two current approaches of modulation upconversion: (a) mixer based, (b) direct modulation of vco. the removal of all mixers can be accomplished by using the vco to perform the required frequency translation. as illustrated in part (b) of the figure, the translation is accomplished by injecting the baseband, analog modulation signal into the input of the vco after the frequency synthesizer has guided the vco output to the desired carrier frequency. phase and/or frequency modulation of a frequency synthesizer is accomplished by varying its divide value according to input data. a simple method of performing this task is shown in figure 2. binary input data selects the divide ratio to be either n or n +1 depending on whether the input is 0 or 1, and n is chosen to achieve the desired carrier frequency. the output frequency settles to fout= nfref, so that binary frequency shift keying (fsk) modulation is produced as n is varied. in the figure, the resulting output spectrum is illustrated under the assumption that fref = 20 mhz and that n = 90. the carrier frequency is seen to be 1.81 ghz, and the modulation frequency deviation equals fref. unfortunately, the fsk modulation method depicted in figure (2) is not practical for most applications due to its inefficient use of spectrum. the spectral efficiency is greatly improved if a smooth transition is made during frequency transitions and the modulation deviation is optimized. fig. 2. direct modulation of a frequency synthesizer. figure 3 illustrates a fractional-n modulator that achieves high spectral efficiency by using a digital transmit filter to obtain smooth transitions in the modulation data, and a digital σ-δ modulator to dither the divide value according to the resulting modulation sequence [2]. fig. 3. a spectrally efficient, fractional-n modulator. gaussian frequency shift keying, or gfsk, represents a filtered form of frequency shift keying. the data to be modulated to rf is prefiltered digitally using a finite impulse response filter (fir). the filtered data is then used to modulate the sigma-delta fractional-n to generate spectrally-efficient fsk. ali mohammed noori hasan al-khwarizmi engineering journal, vol. 4, no. 3, pp 1-7 (2008) 3 fsk consists of a series of sharp transitions in frequency as the data is switched from one level to another. the sharp switching generates higher frequency components at the output, resulting in a wider output spectrum. with gaussianfsk, the sharp transitions are replaced with up to 128 smaller steps. the result is a gradual change in frequency. as a result, the higher frequency components are reduced and the spectrum occupied is reduced significantly. gfsk does require some additional design work as the data is only sampled once per bit, and so the choice of crystal is important to ensure the correct sampling clock is generated. 3. sigma delta modulation: this method will be used to implement fractional n synthesizer in this system to eliminate the fractional spurs. the accumulator used to control the modulus of the prescaler can be viewed as the digital counter part of a firstorder analog σ∆-modulator. the carry of accumulator changes the prescalar from n to n+1 for one cycle figure (4) shows the accumulator, i.e. an adder with a one clock cycle delay in the feedback path, with the corresponding signals. the frequency control word is fed into the a input, and added to the b input to produce a sum output σ. when the adder overflows, the carry out bit c is set[3]. fig.4. the digital accumulator with the corresponding input and output signals. let us denote the frequency control signal fed to input a by xi, and carry output c of the accumulator by yi. when an overflow occurs, the contents of the accumulator are ―flipped over‖, which can be viewed as subtracting the full scale of the accumulator from its contents. the output of the accumulator at an arbitrary time is the sum of its input at that time and its contents one clock period earlier. if an overflow occurs, the full scale of the accumulator is subtracted. the output can thus be expressed as σi = xi + σi-1 – yi …(3.1) yi = xi + σi-1 – σi …(3.2) yi = xi – (σi – σi-1) …(3.3) the z-transform of equation (3-3) is y(z) = x(z) σ(z) (1 – z -1 ) …(3.4) let us now look at the signal flow diagram of a first-order analog σ∆-modulator shown in figure (5). the input is again denoted by x, and the output by y. the operation performed in the dashed box is the quantization, and e denotes the quantization error. fig. 5. the signal flow diagram of a firstorder analog σ∆-modulator. the above modulator is described by the following equations: wi = wi-1 + xi-1 yi-1 …(3.5) yi = wi + ei …(3.6) combining these two, we get yi – ei = yi-1 – ei-1 + xi-1 –yi-1 …(3.7) yi = xi-1 + ei – ei-1 …(3.8) the z-transformation of equation (3.8) is y(z) = z -1 x(z) + e(z) (1z -1 ) …(3.9) comparing equation (3.9) with equation (3.4) shows great similarity. ignoring the latency of one clock period in the signal path of the analog σ∆modulator, and treating the contents of the digital accumulator as the negative of the quantization error, the equations are identical. the signal in the σ∆-output of the accumulator, however, is no longer at dc, although it is periodical. now, this signal can be fed into the input of another accumulator, whose output will be much less periodic than the output of the first accumulator. the first accumulator carry changes the division ratio of the divider from n to n+1 for one cycle. the output is digitally integrated by the second accumulator and its carry output changes the division ratio to n+1 and then n-1 on the next clock cycle. combining the c outputs of the two accumulators in a suitable way (see figure 6), the quantization noise of the first accumulator can be canceled [4]. + ∑1 ∑2 ali mohammed noori hasan al-khwarizmi engineering journal, vol. 4, no. 3, pp 1-7 (2008) 4 fig. 6. the block diagram of a secondorder mash modulator. as shown in equations (3.1) to (3.4), the output of the first accumulator is y1(z) = x(z) – σ1(z) (1 – z -1 ) …(3.10) feeding the σ -output of the first accumulator into the input of the second one, the output of the second accumulator is y2(z) = σ1(z) – σ2(z) (1 – z -1 ) …(3.11) combining the outputs of the accumulators as shown in figure 6, we get the following as the output of the entire modulator: y(z) = y1(z) + y2(z) – y2(z) z -1 …(3.12) y(z) = y1(z) + y2(z) (1 – z -1 ) …(3.13) y(z) = x(z) σ1(z) (1 – z -1 )+ σ1(z) (1 – z -1 ) σ2(z) (1 – z -1 ) …(3.14) y(z) = x(z) σ2(z) (1 – z -1 ) 2 …(3.15) as equation (3.15) shows, the quantization noise of the first accumulator cancels out. this greatly improves the spurious performance of the modulator, since the first accumulator is the one with the more periodical output. also, as equation (3.15) shows, the noise transfer function is now a second-order high pass function. thus, the signal to noise ratio at low frequencies is higher than in a first-order modulator. this concept, called the cascaded modulator or the mash modulator, mash modulators of any order are unconditionally stable if individual modulators comprising the mash are stable. in this case, the individual modulators are first-order ones, and thus always stable. hence, the order of the mash modulator can be increased at will without causing any stability problems. 4. system design: based on theoretical analysis shown in sections two and three, a gaussianfsk transmitter in uhf band by direct modulation of σδ modulator fractional-n synthesizer will be designed for the following requirements :  frequency range:869.9 mhz– 900.4 mhz  channel spacing:500khz  data rate:150kb/s  frequency deviation : 300khz  phase noise:less than -84dbc/hz@10 khz the sigma delta modulator will be used to implement the system since it has the following properties:  eliminating spurious digitally.  allowing good phase noise performance. the sigma delta modulator's type in this system is mash modulator contains three stages of accumulator. the gfsk is selected to provide high spectral efficiency. the frequency deviation is set by the following equation [7]: freq. deviation = (fcrystal * 2 m )/(r * 2 14 ) where r represents reference division, fcrystal represents crystal frequency and m represents modulation control. figure (7) shows the schematic diagram of the system. adf7012 chip contains reference divider, mash modulator, and phase frequency detector. the loop filter is a passive 3rd order filter which is selected in the system because it has the following properties  the least complex loop filter.  smallest resistor thermal noise.  maximum resistance to variation of vco gain & pfd gain. for this system, r1= 1.84k, r2=3.77k, c1= 35.5 pf, c2= 483 pf and c3 = 11.2 pf. cpout 3 vco in 18 osc 2 9 notes: 1. indicative schematic only 2. all power supply connections not shown 3. bypass capacitors and bias resistors not shown 4. for full details see device data sheet muxout 6 gnd gnd gnd le 13 data 12 clock 11 avdd dvdd adf7012 rf out 20 osc 1 8 txdata 4 txclk 5 gfsk / gook only transmit data interface chip programming interface l1 15 lext 1.88nh l2 16 r1 1.84k c2 483pf c1 35.5pf r2 3.77k c3 11.2pf crystal 9.60mhz cp2 cp1 set cp1 and cp2 according to crystal load capacitance antenna l31 c32 l32 c31 vdd fig. 7. schematic diagram of the system. ali mohammed noori hasan al-khwarizmi engineering journal, vol. 4, no. 3, pp 1-7 (2008) 5 5. results of simulation: a system is simulated by adi srdlsim version 1 software & we obtain the following results: 1. single frequency simulation of transmitter: figure (8) shows block diagram of test configration for the transmitter: device under test spectrum analyzer modulation domain analyzer antenna terminal test configuration conducted power fig. 8. block diagram of test configuration. from this test , the following results of single frequency 900mhz and span 1mhz of spectrum analyzer are obtained and shown in figures (9) and (10). -500 -400 -300 -200 -100 0 100 200 300 400 500 frequency (khz) -25 -20 -15 -10 -5 0 c o n d u c te d p o w e r (d b m ) spectrum analyzer fig.9. spectrum analysis of single frequency 900 mhz transmitter with span 1mhz. 0 2 4 6 8 10 12 14 time (us) -400 -300 -200 -100 0 100 200 300 400 d e v ia ti o n ( k h z ) modulation domain analyzer fig.10. modulation domain analysis of gfsk transmitter at frequency 900 mhz. 2. phase noise: it is the most critical parameter which describes short term frequency instability include fluctuations in signal ’ s phase or frequency that less than 1sec. this is shown in figure (11). 10k 100k 1m 10m 100m frequency (hz) -160 -150 -140 -130 -120 -110 -100 -90 -80 -70 -60 p h a s e n o is e ( d b c /h z ) phase noise at 900mhz total loop filter chip ref vco fig.11. phase noise of fractional synthesizer. 3. settling time: it is defined as the time needed for switching the synthesizer from one frequency to another. the settling time of our synthesizer is less than 2μsec for frequency switching (870-890) mhz as shown in figure (12). 0 1 2 3 4 5 6 7 8 9 10 11 time (us) 780 800 820 840 860 880 900 920 f re q u e n c y ( m h z ) power-on transient fig.12. settling time. 6. discussion and conclusions: the uhf gfsk transmitter has been presented by direct modulation of fractional synthesizer. the simulation results of this transmitter achieve the following specifications:  frequency range:869.9 mhz–900.4 mhz  channel spacing : 500khz  data rate : 150kb/s  frequency deviation : 300khz  phase noise:less than -84dbc/hz @10 khz ali mohammed noori hasan al-khwarizmi engineering journal, vol. 4, no. 3, pp 1-7 (2008) 6 the system is proposed in this research that allows fractional-n frequency synthesizers to be directly modulated at low data rates while simultaneously achieving good noise performance. the technique allows digital phase/frequency modulation to be achieved without mixers or d/a converters in the modulation path. the resulting transmitter design is primarily digital in nature and reduced to its fundamental components—a frequency synthesizer that accurately sets the output frequency, and a gaussian filter that provides good spectral efficiency. among various techniques, the σ∆-modulator fractional-n synthesizer has been selected to provide direct modulation of transmitter since it has several advantages:  low feedback –divider ratio results in lower phase noise with fine step size.  low phase noise contributions are lowered by 20log (l), where l is the fractional modulus.  larger loop b.w. results in lower lock time. the direct modulation method by fractional synthesizer is preferred on traditional methods of transmission because it provides the following benefits:  low power consumption.  low cost.  small size. 7. references: [1] a. a. abidi, ―direct-conversion radio transceivers for digital communications,‖ in proceedings of ieee international solid-state circuits conference, pp. 186–7, 1995. [2] t. a. riley and m. a. copeland, ―a simplified continuous phase modulator technique,‖ieee transactions on circuits and systems — ii: analog and digital signal processing, vol. 41, no. 5, pp. 321–328, may 1994. [3] goldberg, bar-giora., ―digital frequency synthesis demystified‖,1999. [4] j.a crawford, ―frequency synthesizer design handbook‖, artech house, norwood, 1994. [5] dean banerjee ―pll performance , simulation & design‖ 4 th edition, 2005. [6] li lin, ―design techniques for high performance integrated frequency synthesizers for multi-standard wireless communication applications‖ university of california, ph.d., thesis, 2000. [7] the analog device series data sheet, 2004. [8] w. djen and p. shah, ―implementation of a 900 mhz transmitter system using highly imtegrated asic,‖ in ieee 44th vehicular technology conference, pp. 1341–5 vol. 2, june 1994. [9] lascari lance, ―accurate phase noise prediction in pll frequency synthesizers‖ applied microwave & wireless, vol. 12, no.5, may 2000. [10] i. a. koullias, j. h. havens, i. g. post, and p. e. bronner, ―a 900 mhz transceiver chip set for dual-mode cellular radio mobile terminals‖, in proceedings of ieee international solid-state circuits conference, pp. 140–1, feb. 1993. ali mohammed noori hasan al-khwarizmi engineering journal, vol. 4, no. 3, pp 1-7 (2008) 7 σδ مرسلة باستعمال مركب ترددات من نوع gaussian fskتصميم ومحاكاة modulator fractional-n علي محمذ نوري جايؼت بغذاد /كهٛت ُْذست انخٕاسصيٙ/ قسى ُْذست انًؼهٕياث ٔاالحصاالث الخالصة ( σδ modulator fractional-n يشسهت باسخؼًال يشكب حشدداث يٍ َٕع gaussianfsk انبحث انٗ حصًٛى ٔيحاكاة ٚٓذف يذٖ انفصم بٍٛ انقُٕاث ،(150kb/s)يٛكا ْشحض، َسبت حذفق انًؼهٕياث ( 900.4 – 869.9) يذٖ انخشدداث انخاسجت: ٔبانًٕاصفاث انخانٛت (500khz)، حقُٛاث انذٔائش . ْشحض يٍ انخشدد انخاسج10000دٚسبٛم ػُذ (85-)ياٚكشٔ ثاَٛت ٔيسخٕٖ ضٕضاء طٕس٘ 1صيٍ ححٕٚم خٕاص يثم قهت اسخبذاد انقذسة، صغش انحجى ٔ قهت .انحذٚثت ساًْج بشكم فاػم فٙ صٚادة انخكايم نهًشسالث ٔانًسخهًاث الشاساث انشادٕٚ اٌ انخضًٍٛ انًباشش بٕاسطت يشكب انخشدداث يٍ . انكهفت ْٙ انخٙ حؼخبش انًقٛاط انخاص بانخصًٛى ٔانخٙ يٍ خالنٓا ٚخى انحكى ػهٗ اداء انُظاو ٔرنك الٌ ْزِ انطشٚقت حؤيٍ انخٕاص انخٙ َحخاجٓا يثم قهت اسخبذاد انقذسة ٔصغش حى اقخشاحّ فٙ ْزا انبحثσδ( fractional n)َٕع فٙ دٔسة قفم انطٕس انشقًٙ نهسٛطشة ػهٗ انقًٛت انكسشٚت نًقسى انخشدد ٔبٕاسطخّ ٚخى ٔضؼجσδػًهٛت انخضًٍٛ يٍ َٕع . انحجى ٔقهت انكهفت انز٘ حى اسخخذايّ نهحصٕل ػهٗ (gaussian fsk)َٕع انخضًٍٛ . اصانت انطفٛهٛاث يغ يسخٕٖ طفٛهٛاث اقم ٔيسخٕٖ ضٕضاء طٕس٘ جٛذ انسٛطشة ػٍ بؼذ ، اَظًت االياٌ، اٌ انخطبٛقاث نٓزِ انًشسهت ْٙ قهت كهفت َقم انًؼهٕياث انالسهكٙ. كفاءة طٛفٛت ػانٛت فٙ االشاسة انًضًُت .ٔانؼذاد انالسهكٙ (rf)بٕاسطت اشاساث al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 4, no. 2, pp 6975 (2008) dynamic analysis of thin composite cylindrical and spherical shells qusai h. jebur technical college-baghdad foundation of technical education email: kusay74hj@yahoo.com (received 10 decemper 2006; accepted 2 january 2008) abstract in this work, an investigation for the dynamic analysis of thin composite cylindrical and spherical shells is presented. the analytical solution is based upon the higher order shear deformation theory of elastic shells from which the developed equations are derived to deal with orthotropic layers. this will cover the determination of the fundamental natural frequencies and mode shapes for simply supported composites cylindrical and spherical shells. the analytical results obtained by using the derived equations were confirmed by the finite element technique using the well known ansys package. the results have shown a good agreement with a maximum percentage of discrepancy, which gives a confidence of using this solution in prediction the dynamic analysis of cylindrical and spherical shells. keywords: dynamic, composite, cylindrical, spherical, shells. 1. introduction a shell is a three-dimensional body which is bounded by two closely spaced curved surfaces, the distance between the surfaces, being small in comparison with the other dimensions [1]. a shell is considered to be a thin shell when the shell thickness is less than 1/20 of the wavelength of the deformation mode and/or radius of curvature and at the small time, it is assumed that both shear deformation and rotary inertia are ignored. the dynamic analysis of shells has been expanding rapidly due to the importance of shell structures in civil, mechanical and aerospace engineering. the thin composite cylindrical and spherical shells are found in many aerospace and aircraft industrial applications such as aircraft wings and fuselage radomes, ewacs and fuel tanks. also, the composite cylindrical shells are found in compressor blades, ships and rocket. humayun r.h. kabir [2] investigated analytically the free vibration of composite shallow cylindrical shells with simply supported boundary conditions using kirchoff-love theory. h.m. wang [3] investigated the dynamic solution of a multi layered hollow cylinder in a state of axisymmetric plane strain. the solution is divided into two parts: one is quasi-static and the other is dynamic. the qusai static is solved by the state space method, and the dynamic part is obtained by the separation of variables coupled with the initial parameter method . rong-tyai & zung-xian lin [4] presented the formulation of governing equations for a symmetric cross-ply laminated cylindrical shell with a circumferential stiffener. penzes and burgin [5] were the first to solve the problem of the free vibrations of thin isotropic spheroid al shells by using galerkins method using membrane theory and harmonic axisymmetric exitation. al-najim f. [6] used the rayliegh method to obtain the natural frequencies and mode shapes of axisymmetric vibrations of thin elastic oblate spheroidal shells theoretically and experimentally. he showed that the rayleigh's method is suitable to deal with such types of problems. from the previous literatures, it is found that there is still a chance to work in this field especially for the analysis of composite cylindrical and spherical shells and therefore this work will be devoted in this respect analytically using the higher order shear deformation theory mailto:kusay74hj@yahoo.com qusai h. jebur al-khwarizmi engineering journal, vol. 4, no. 2, pp 69-75 (2008) 70 and numerically using the finite element method. mathematical analysis the review of literature reveals that the governing equations for thin spherical shells are not available. the following formulation gives the free formulation for the thin shells of revolution which can be applied for both cylindrical and spherical shells. based upon the third-order theory of reddy using the displacement field ref. [7]:                   x w h z tyxztyxutzyxu 0 12 3 10 3 4 ),,(),,(),,,(   ),,(),,,( 3 4 ),,(),,(),,,( 0 2 0 22 3 20 tyxwtzyxw x w h z tyxztyxvtzyxv                      the resulting strain-displacement relations are:                          2 1 0 2 1 1 2 3 1 1 1 0 1 3 4 x w xh z x z x u                                   2 2 0 2 2 2 2 3 2 2 2 0 2 0 2 3 4 x w x h z x z r w x v    03                                              21 0 2 2 1 1 2 2 3 1 2 2 1 2 0 1 0 6 2 3 4 xx w xx h z xx z x u x v                           2 0 22 2 2 0 24 4 x w h z x w                    1 0 12 2 1 0 15 4 x w h z x w  ...(1) appling hamilton’s principles, the resulting equations contain double and triple integrals and because of the variation principle of displacements, the coefficient of the variations displacements is zero from which the following equations of motion are obtained:   0 1 2  t t tku  …(2) where: dzdxrd u za      4455 66332211          t v dtdzdxdwwvvuurk  ...... carrying out the above integrations will give the followings: x w r i i h r i i hr i i u r i x n x n                                                 .. 1 5 42 2 .. 1 5 42 1 3 2 .. 1 1 2 6 1 1 3 4 3 4 2  …(3) 2 .. 2 5 42 .. 2 2 1 2 .. 2 5 42 2 3 2 1 6 2 2 3 42 3 4 x w r i i h v r i i r i i hr i i x n x n                                                                  …(4) .. 1 2 .. 2 4 5 2 4 2 5 1 4 2 5 1 4 2 2 2 1 16 2 2 1 1 2 2 2 2 2 2 9 16 3 4 4 2 3 4 wi x v rh i h i q x q x q x k x k h r n r n x s x s x s h                                                                            x u r i i hx h i h i r x w x w h i h i xh i h i                                                                                                         .. 1 5 42 1 1 .. 2 5 4 7 2 2 .. 2 2 1 .. 2 4 7 2 4 2 2 .. 2 5 4 7 3 4 3 4 9 16 9 16 3 4 3 4 9 16   …(5) qusai h. jebur al-khwarizmi engineering journal, vol. 4, no. 2, pp 69-75 (2008) 71 1 .. 4 7 2 5 .. 14 7 2 5 3 .. 1 5 42 1 3 252 5 2 6 2 2 6 1 1 2 1 1 9 16 3 8 9 16 3 8 3 44 3 4 3 4 x w h i h i h i h i i u r i i hr i ik h q x s hx m x s hx m                                                               …(6) 2 .. 4 7 2 5 .. 24 7 2 5 3 .. 2 5 42 2 3 242 4 1 6 2 1 6 2 2 2 2 2 9 16 3 4 9 16 3 8 3 44 3 4 3 4 x w h i h i h i h i i v r i i hr i ik h q x s hx m x s hx m                                                               ...(7)         5,4,1, 6,3,2,1,,1,, 2 3     idzzkiqi idzzzsimini i i       7,6,5,4,3,2,1 ,,,,,,1 65432    idz zzzzzzi ii  substituting the above resultant forces in the developed equations and then the assumed displacement components according to navier׳s solution ref. [8] (for simply supported boundary conditions), the stiffness and mass matrices are obtained. solution of the developed equations: the solution is assumed as follows:     mni m n mn mni m n mn exbtzxv exatzxu                 1 1 0 1 1 0 cossin,,, sincos,,,     mni m n mn mni m n mn exdtzx exctzxw                 1 1 1 1 1 0 sincos,,, sinsin,,,   mni m n mn exetzx        1 1 2 cossin,,, … (8) where α=       l m , β=n the mass and stiffness matrices are obtained from the solution of the eigenvalue equation as follows:      02  amk  …(9) from which the natural frequencies and mode shapes are obtained. finite element modeling finite element modeling for the laminated shells is done using ansys (5.4), following the major steps [9]: 1. building the structure using quad shell element 99 as shown in fig. (1). 2. applying boundary conditions. 3. solve the natural frequency problem and getting the results. fig. 1. 100-layer shell-99 element. results and discussions the developed analytical solution using the general third order shear deformation theory (hsdt) will be employed to investigate its applicability in investigating the dynamic analysis of symmetric and non-symmetric crossply laminated cylindrical and spherical shells. the results are composite plates used by other researchers. (a) spherical shell in order to obtain the fundamental natural frequencies from the developed analytical solution, different ratios of radius-to-side length 5,10 and 20 for both type of shells thin(a/ h) =100 and thick (a/h)=10 for the composites (0,90,0) and (0,90,90,0).the results are shown in table 1. it is seen that the maximum percentages of discrepancy is 8.97%. the results indicate that the thicker shells have lower frequency parameter than the thinner shells, and for shells with smaller (r/a) the frequency parameter is greater than that for larger ratios .in the above calculations the material properties are as followings [10]. e1=2e6, e2=e3=1e6, g12=g13=0.5e6, g23=0.2e6, ν12 = ν13 = 0.24, ν23 = 0 another interesting result is that the fundemenral frequency for symmetric shells is qusai h. jebur al-khwarizmi engineering journal, vol. 4, no. 2, pp 69-75 (2008) 72 greater than that for antisymmetric one. however, fig. 2 shows the first three modes shapes for the spherical shell of composite type (0,90). the shapes are consistent with the predicted modes. fig. 3 shows the frequency parameter change 2 2 eh a        with the ratio (a/h) which shows that the fundamental natural frequency is increased with the increasing (a/h) ,for both types of composites investigated ( 0,90,0) and (0,90) (b) cylindrical shell general third order theory (hsdt) is employed to investigate its capability level for dynamic analysis of the symmetric and nonsymmetric cross-ply laminated cylindrical shells, and compared with other theories used by other researchers such as fsdt. in this respect, the fundamental natural frequency was obtained for the ratios of radius to side length (5, 10, and 20) and (a/h)=100 thick shell and (a/h)=10, thin shell using the composite, (0,90,0) and ( 0, 90, 90, 0). the results of using higher shear deformation theory are compared with those obtained from using first order shear deformation and the ansys package with a percentage of discrepancy 9 %. the results indicates a decrease in the frequency parameter, for example for composite (0,90) a decrease from 16.69 for (r/a)= 5 and 10.27 for (r/a)= 20 while in thin cylinder (a/h)= 10, no noticeable change , the frequency parameter decreases from 9.023 for (r/a)= 5 to 8.972 for (r/a)= 2. similar trends were noticed for the other composites. however fig. 4 shows theses trends for both composies (0, 90) and (0, 90, 0). table 1 nondimensionalized fundamental frequencies versus radius-to-side length ratios of spherical shell. (r/a) theory [0-90] [0-90-0] [0-90-90-0] (a/h)=100 (a/h)=10 (a/h)=100 (a/h)=10 (a/h)=100 (a/h)=10 5 fst 28.825 9.230 30.993 12.372 31.079 12.437 present work 28.829 9.307 30.999 12.018 31.083 12.007 fem 27.563 8.872 29.253 11.563 30.146 11.683 discrepancy% 4.3 4.7 5.63 3.67 3 2.6 10 fst 16.706 8.984 20.347 12.215 20.380 12.280 present work 16.710 9.064 20.353 11.853 20.385 11.840 fem 16.001 8.254 19.754 11.102 19.831 11.024 discrepancy% 4.24 9 2.9 6.1 2.71 6.64 20 fst 11.841 8.921 16.627 12.176 16.638 12.240 present work 11.847 9.002 16.634 11.811 16.643 11.798 fem 11.011 8.201 16.001 11.310 15.885 11.023 discrepancy% 7.06 8.97 3.807 4.11 4.55 6.33 table 2 nondimensionalized fundamental frequencies versus radius-to-side length ratios of cylindrical shell. (r/a) theory [0-90] [0-90-0] [0-90-90-0] (a/h)=100 (a/h)=10 (a/h)=100 (a/h)=10 (a/h)=100 (a/h)=10 5 fst 16.668 8.9082 20.332 12.207 20.361 12.267 present work 16.690 9.0230 20.330 11.850 20.360 11.830 fem 16.001 8.731 19.705 11.203 19.871 11.211 discrepancy% 4.13 4.99 3.54 2.86 3.09 4.55 10 fst 11.831 8.887 16.625 12.173 16.634 12.236 present work 11.840 8.979 16.620 11.8 16.630 11.79 fem 11.151 8.535 16.031 11.451 16.115 11.233 discrepancy% 5.82 4.99 3.54 2.86 3.09 4.55 20 fst 10.265 8.89 15.556 12.166 15.559 12.23 present work 10.27 8.972 15.55 11.79 15.55 11.78 fem 9.891 8.420 15.067 11.247 15.004 11.136 discrepancy% 3.69 6.2 3.1 4.48 3.509 5.265 qusai h. jebur al-khwarizmi engineering journal, vol. 4, no. 2, pp 59-75 (2008) 73 (a)first mode (b)-second mode (c)-third mode fig. 2 mode shapes of [0-90] spherical shell. 0 20 40 60 80 100 (a/h) 8 12 16 20 24 f re q u e n c y p a ra m e te r [0-90-0] [0-90] fig. 3 frequency parameter 2 2 eh a         change with (a/h) for cylindrical shell. 0 20 40 60 80 100 (a/h) 0 10 20 30 40 f re q u e n c y p a ra m e te r [0-90-0] [0-90] fig. 4 frequency parameter 2 2 eh a         change with (a/h) for spherical shell qusai h. jebur al-khwarizmi engineering journal, vol. 4, no. 2, pp 59-75 (2008) 74 conclusions the following points may be summarized from the current work: 1. the developed analytical solution may be used for the dynamic analysis of thin composite shell, spherical or cylindrical and may be extended to the conical shells. the validity obtained between the analytical and numerical results were in good agreement with a maximum discrepancy of 6.2%. 2. the natural frequency tends to increase with the increasing of radius to side length for all the composite shells (0, 90, 0, 90, 0) and (0, 90, 90, 0). 3. the natural frequency is decreased with increasing the radius/side ratio for all the types of composites. (0, 90), (0, 90, 90, 0). 4. the frequency parameter 2 2 eh a         for spherical shell is more than that of the cylindrical shell for the same radius/side ratio. nomenclature a : radius mm a : side length (mm) e : modulus of elasticity (n/m 2 ) g : modulus of rigidity (n/m 2 ) h : thickness (mm) ii : integrations mi : resultant moments per unit length n.m/mm ni : resultant forces per unit length n/m ρ : density (kg/m 3 ) r : radius (mm) t : time (sec) u, v, w : displacement components in x, y, and z directions respectively (mm) δu : change in strain energy (n.m) δk : change in kinetic energy (n.m) εi : strain component in the principal direction (i, i=1,….6) ζi : stress component in the principal direction (i, i=1,….6) φi, θi : rotations ω : frequency (rad/s) ν : poisons ratio references [1] timoshenko "theory of plates and shells" [2] humayun r h. kabir,"application of linear shallow shell theory of reissner to frequency response of thin cylindrical panel with arbitrary lamination" comp.stru. vol. 56, 2002. [3] h.m wang "dynamic solution of multilayered orthotropic piezoelectric hollow cylinder for axisymmetric plane strain problems" int.j of solid and strctures,vol.42,2004 [4] rong-tyai wanga and zung-xian lin "vibration analysis of ring-stiffened cross-ply laminated cylindrical shell" j.of sound and vibration, vol.295, 2006. [5] penzes l.and buring g "free vibration of thin isotropic oblate spheroidas shells"generas dynamic report no gd/c-btd 65-113, 1956 [6] al-najim , f.a"an investigation into the free ax. symmetric vibration charachterstks shell" m.sc thesis, university of baghdad, 1990 [7] al-azzawy w. i. “fatique and vibration characteristics of laminated composite shelles of revolution” ph. d thesis, university of baghdad, 2007 [8] reddy, j. n. and lium c. f. “a higher–order shear deformation theory of laminated elastic shells”, international journal of eng. since, vol. 23, no.3, 1985 [9] b.m pandya and t kant "finite element of laminated composite plates using a higher order displacement model", composite science and technology 1988. [10] george lubin "hand book of composites", van nostrand reimhold compony, inc, 1982. qusai h. jebur al-khwarizmi engineering journal, vol. 4, no. 2, pp 59-75 (2008) 75 التحليل الذيناميكي للقشريات االسطوانية والكروية الخفيفة المصنوعة من مواد مركبة قصي حاتم جبر .هيئت انخعهيى انخقُي بغذاد/انكهيت انخقُيت الخالصة اسخُذ انحم انخحهيهي عهى َظشيت حشىِ انقض يٍ . في هزا انبحث حى دساست انخحهيم انذيُبييكي نهقششيبث االسطىاَيت وانكشويت انًشكبت اٌ رنك يشًم ايجبد انخشدداث . انشحبت انعهيب نهقششيبث انًشَت وانخي يُهب َسخطيع اشخقبق انًعبدالث انخبطت ببنطبقبث انغيش سىيت انخىاص . انطبيعيت واَسبق االهخضاصاث نهقششيبث االسطىاَيت وانكشويت انًشكبت وانًسُذة ببسبطت . ansyحى اثببث انُخبئج انخحهيهيت وانخي حى انحظىل عهيهب ببسخخذاو انًعبدالث انًطىسة بىاسطت حقُيت انعُبطش انًحذدة يٍ خالل بشَبيج . في انخحهيم انذيُبييي نهقششيبث االسطىاَيت وانكشويت%9بيُج انُخبئج حىافقب جيذا وببعظى َسبت حفبوث (microsoft word 91-99 \345\310\311 \346\324\337\321\355) al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 15, no. 4, december, (2019) p. p. 9199 effects of sodium chloride and sodium sulphate solutions on the output of the electrochemical machining heba saad qasim* shukry h. aghdeab** *,**department of production engineering and metallurgy/ university of technology *email: gaithalaa468@yahoo.com **email: shukry-hammed@yahoo.com (received 29 may 2019; accepted 28 october 2019) https://doi.org/10.22153/kej.2019.10.004 abstract electrochemical machining is a term given to one of nontraditional machining that uses a chemical reaction associated with electric current to remove the material. the process is depending on the principle of anodic dissolution theory for evaluating material removal during electrochemical process. in this study, the electrochemical machining was used to remove 1 mm from the length of the a workpiece (stainless steel 316 h) by immersing it in to electrolyte (10, 20 and 30 g) of nacl and na2so4 to every (1 litter of filtered water). the tool used was made from copper. gap size between the workpiece and electrode is (0.5) mm. this study focuses on the effect of the changing the type and concentration of electrolyte solution, the effect of the value of current (2, 5 and 10) a and the effect of the value of the voltage (6, 12 and 20)v on the surface roughness (ra) and material removal rate (mrr) of the workpiece. the results of comparison of experimental showed that (na2so4) solution give surface roughness less than (nacl) solution in all levels, maximum (ra) is (0.658) and minimum (0.420), while (nacl) solution give maximum (ra) is (2.913) and minimum is (0.508), also give (mrr) higher from (nacl) solution in level (30 g/l ) at (5 a) , (10 and 20 g/l) at (10 a) ,and (30)g/l at (6 &12 v). this study aims to compare the effect of using different electrolyte solution including sodium chloride (nacl) and sodium sulphate (na2so4) on the surface roughness (ra) and material removal rate (mrr). generally increasing in machining parameter (concentration of solution, current and voltage) lead to increase in (mrr) and (ra). keywords: electrochemical machining, surface roughness, electrolyte concentration. 1. introduction the electro-chemical machining (ecm) is an advanced machining operation and, potentially, it is the highly beneficial process of material removal of non-conventional machining operation [1]. it’s named via such term since the electric energy is utilized in a integration with the chemical reaction to complete the sweep of metal [2]. such process depends upon the electrolysis principle for the removal of metal, which is based on a controlled anodic electrochemical dislocation process of the workpiece (anode) with the tool (cathode) in an electrolytic cell. the solution of electrolyte is generally a mineral salt as a sodium nitrate (nano3), acid such as (hcl) and alkaline such as (naoh) [3]. the metal removal rate is governed by the miechael faraday's law of electrolysis. gusseff presented the first patent on (ecm) in 1929,s, and the first important evolution took place in 1950,s, when the operation was the high-strength and heat resistance alloy machining [4]. this process was universally accepted as standard operation in production and is able to machine hard material work parts, which are difficult-to-machine and precise. and after the second world war, the technology became more popular result as the demanding processing of hard alloys by martial and aerospace applications [5]. mcgough 1988 asserted that if a potential discrepancy is exerted heba saad qasim al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 9199 (2019) 92 across the electrodes, many possible reactions take place at the cathode and the anode. electrolysis has included the iron (fe) dissolution from the anode and the hydrogen (h2) generation at the cathode [6]. ecm is used in many applications, for example, automotive and medical principle user. this operation has found good applications in industries related with the manufacture of aircraft edging parts, turbine blades and grinding of carbide tools and dies [7]. table (1) represent the difference between conventional machining and ecm. jo ao cirilo da silva neto, et al. 2006[8] studied the intervening parameters in the ecm of valve-steel. the mrr, roughness and over-cut were investigated. 4 parameters were varied within the experiments: electrolyte, voltage, rate of feed, and the electrolyte flow rate. two electrolytic solutions were employed: nacl and nano3. results showed that the rate of feed was the major parameter influencing the mrr and the electrochemical machining with the nano3 gave the best surface roughness and over-cut results. anil kumar meher, et al 2009 [9] intended to deal with the process characteristics of ecm and how it is affected by the process parameters. the electrolyte solution was used nacl (100gm/lt). and in this research tow parameters was used (voltage and feed rate). the results show that feed rate was the main parameter affecting the mrr. andi sudiarso et al. (2016) [10] studied the process parameters, like concentration of electrolyte (nacl) and voltage. the optimization goal was to get the highest value of material removal rate (mrr) and the lowest overcut (oc). the research was conducted by varying 3 levels of voltage 9.5, 11 and 12.5 v, 3 levels of nacl concentration 100, 150 and 200 g/l and 3 times the replication of full factorial design approach (ff). machining was done by using die sinking method with stainless steel 204, for both the electrode and work-piece. the results obtained from this research showed that the voltage and nacl concentration have a significant influence on the value of mrr and overcut, where their influences are formulated in the form of linear regression models. besides that, the highest mrr was obtained at a voltage of 12.5 volts and nacl concentration 200 g/l with value 17.86 × 10-4 g/s. table,1 the unlikeness between traditional machining and ecm process [11]. 2. the electrochemical reaction the electrochemical reaction is the chemical reaction that takes place in the solution at the interface of an electronic conductor (a metal) and ionic conductor (electrolyte), and it involves electron transfer between the electrode and electrolyte or species in solution and this reaction is driven by external applied voltage [12]. the chemical reaction is that involved a transfer of electrons can be used to produce an electric current [13]. the material removal is executed by taking part of an electrolyte between the tool material (cathode) and the workpiece (anode) and across a very small cavity between them. gas bubbles generated in the electrode gap and the dislocation product such metal hydroxide is removed by the electrolyte. electrochemically using (nacl) solution as electrolyte [14]: nacl→na++cl …(1) h2o→h++oh …(2) traditional machining ecm process acommunicate between the tool and the wp. ano communicate between the tool and the wp. bremove of metal by shearing and friction methods. bremove of metal by anodic dissolutions methods. crelying on the mechanical properties of material. crelying on electrical conductivity of material and chemical reactions of the operation. drequirement for reshape the tools or it sever wear. d not requirement for reshape the tools and do not sever wear. ethe chip forming as a stiff body. e the chip forming as a rustiness. fthe model of the tool depend on the kind of process. fthe shape of the tools depend on the ultimate shapes of the product. gusing the cooling liquid to reduce the heat generation during the process. g the electrolyte that use in ecm operation can also reduce the heat generation. husing the cooling liquid to reduce the heat generation during the operation. hthe electrolyte that use in ecm operation can also reduce the heat generation. heba saad qasim al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 9199 (2019) 93 positive charged captions: h+ and na+ toward cathode and negatively charged anions: (oh) and (cl-) go towards anode. so the anode metal (workpiece) becomes [2]: fe→fe+2+2e …(3) when the metal ions leave the workpiece surface (anode), many reactions occur in the electrolyte. fe+2+2cl-→fecl2 …(4) fe+2+2oh-→fe(oh)2 …(5) fecl2+2oh-→fe(oh)2+2cl ...(6) this ferrous hydroxide (fe (oh)2 ) is a green black precipitate. (cl-) ions may loose an electron and hence undergoes oxidation at the anode leading to evolution of chlorine gas at anode: 2cl-→cl2+2e …(7) 2fecl2+cl2→2fecl3 …(8) h++cl-→hcl …(9) green-black ferric hydroxide (fe(oh)2) reacts with the oxygen to form ferric hydroxid (fe(oh)3 ) which is red-brown in color [9]. figure (1) represent electrochemical reaction during ecm of iron. 2h2o→o2↑+4h++4e …(10) 2fe(oh)2+h2o+o2→2fe(oh)3↓ ...(11) fe(oh)3↓3hcl→fecl3+3h2o ...(12) fecl3+3naoh→fe(oh)3↓+3nacl ....(13) 3. electrochemical reactions for sodium sulphate (na2so4) h2o→h++oh …(14) na2so4→2na++so4-2 …(15) fe→fe+2+2e …(16) when the metal ions leave the workpiece surface (anode), many reactions occur in the electrolyte. fe+2+so4 -2→feso4 …(17) fe+2+2oh-→fe(oh)2 …(18) feso4+2oh-→fe(oh)2 + so4 -2 …(19) this ferrous hydroxide (fe (oh)2 )is a green black precipitate. 2so4 -2→so4+2e …(20) 2feso4+so4→2fe(so4)3 ...(21) h++so4 -2→-hso4 ..(22) green-black ferric hydroxide (fe (oh)2) reacts with the oxygen to form ferric hydroxid (fe(oh)3) which is red-brown in color 2h2o→o2↑+4h++4e …(23) 2fe(oh)2+h2o+o2→fe2(oh)3↓ ...(24) fe2(oh)3+3hso4→fe2(so4)3+3h2o ...(25) fe2(so4)3+6naoh→2fe(oh)3↓+3na2so4 ...(26) 4. calculation of mrr exp the actual mrr can be determined by the [15]: mrr exp= ����� �� (g/min) ...(27) where: mrr exp = experimental material removal rate. wb = weight of the workpiece before ecm machining (g). wa = weight of the workpiece after ecm machining (g). mt =machining time (min). 5. experimental work 5-1 in electro-chemical machining (ecm) using drilling machine, as shown in fig (2), wp material was chosen from (stainless steel aisi 316), with dimension (40x 30) mm and thickness (2) mm. figures (2) and figure (3) represents the workpiece before and after machining. the percentages of chemical composition is given in table (2). 5-2 tool material was chosen from copper dimension (110x30) mm and thickness (6) mm, as shown in fig (4), with using nine sample and change in machining parameter (concentration of electrolyte solution, current and voltage). 5-3 the main parts of ecm machine, as shown in figure 5. apower supply the power supply is a very important device to provide the current that helps the electrochemical reaction to occur by forcing the electrons to move from the work piece through it to the tool. the power supply used in the experiment work a d.c power type with different currents from (0-30 a). and voltages from (0-50v). belectrolyte pump: it is put into the chamber of reaction. it will pumping the electrolyte into the cavity between the tool and workpiece to prevent sludge for plain operation. c reaction chamber: it is the cell used for the electrochemical reaction between the workpiece and the electrolyte, this chamber is made from glass, with the dimensions (450x200x260) mm3. delectrolyte: the electrolytes were used in this process mixture from a water filtered and sodium nitrite (nacl), and the other solution using (na2so4) (sodium sulphate) with concentrations (10, 20 and 30) (g/l). heba saad qasim al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 9199 (2019) 94 6. surface roughness measurements in this work, the surface roughness (ra) measurement was taken at three different regions on the machined surface. the mean of these three measurements was taken as the final value for the surface roughness and measured in µm. a profilemeter made by maher federal company, type pocket surf ps1 was used to measure ra. the probe scans the surface and compares between peaks and valleys to indicate the sr. fig. 2. chemical compositions of wp (stainless steel 316) fig. 3. wp (stainless steel aisi 316) after machining. fig.4. the copper electrode. fig.5. ecm machine. fig. 6. surface roughness device. gap indicator reaction chamber electrolyte inlet negative pole positive pole heba saad qasim al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 9199 (2019) 95 table 2, chemical compositions of wp (stainless steel 316). c% si% mn% p% s% cr% mo% 0.057 0.391 1.769 0.035 <.0005 18.73 0.284 al% ni% cu% v% w% fe% <.001 8.69 0.338 0.063 0.042 bal. 7. results and discussion 7.1 effect of the concentration of solution, current and the voltage on ra. the surface roughness of the workpiece increases with increasing the value of the voltage and the value of the current intensity. the increase in the current intensity lead to increase in movement of ions associated with the machining operation in the machining zone metal lead to increase temperature and surface roughness [11]. also increase in concentration of solution lead to increase in number of positive and negative ions lead to increase speed of chemical reaction and increase the temperature and surface roughness. as shown in figure 7, 8 and 9. fig.7 explains the effect concentration of solution (10,20,30)g/l, the value of the current (2)a and the value of the voltage (6)v. maximum surface roughness for nacl is (2.088)µm, and minimum value is(0.508), and maximum surface roughness for (na2so4) is (0.480)µm, and minimum value is (0.420). fig. 7. effect of concentration at current (2a) and (6v) on surface roughness. fig.8 explains the effect concentration of solution (10,20,30)g/l, the value of the current (5 a) and the voltage of (12v). maximum surface roughness for nacl is (2.913)µm, and minimum value is(2.043), and maximum surface roughness for (na2so4) is (0.503)µm, and minimum value is (0.561). fig. 8. effect of concentration at current (5a) and (12) on surface roughness. fig.9 explains the effect concentration of solution (10,20,30)g/l, current (10a) and the voltage of (20)v. maximum surface roughness for nacl is (2.913) µm, and minimum value is (2.043), and maximum surface roughness for (na2so4) is (0.503)µm, and minimum value is (0.561). fig. 9. effect of concentration at current (10a) and voltage (20) on surface roughness. 0 0.5 1 1.5 2 2.5 3 3.5 0 10 20 30 40 r a ( µ m ) concetration( g/l) current current current current 5 5 5 5 (a) (a) (a) (a) nacl na2so4 heba saad qasim al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 9199 (2019) 96 7.2 effect of the concentration of solution, current and the voltage on mrr. increase in the voltage and current intensity lead to increase in material removal rate because the amount of mass dissolved is straight commensurate to the offset of electricity which has flowing" according to faraday's lows, in the medium of operations will dash the chemical reactions at high values of current that give better results [12] and increase in electrolyte concentration lead to increases the mrr. this can be attributed to increase in the electrical conductivity of the electrolyte with increase in concentration as a result of which machining current in the inter electrode gap (ieg) increases. further, at higher concentration, a large number of ions accumulated in the (ieg) increase the machining current and thus enhances the material removal rate [13]. table 3 and 4 reperesents experimental impact of the machining parameters on and ra and mrr of (nacl) and (na2so4) solution respectivily. table (3) and(4) represente the values of exeperimental impact of machining parameters on (ra) and (mrr) of (nacl) and (na2so4) respectivily. fig.10 explains the effect of current (2,5 and 10) a, voltage (6v) and the concentration (10)g, maximum material removal rate for nacl is (0.016)g/min, and minimum value is(0.007) g/min, and maximum removal rate for (na2so4) is (0.023)g/min, and minimum value is (0.0067)g/min. fig.10 effect of current at voltage (6v) and the concentration (10) g/l on material removal rate. fig.11 explains the effect of current (2,5,10) a, voltage (12v) and the concentration (20)g, maximum material removal rate for nacl is (0.02)g/min, and minimum value is(0.008) g/min, and maximum removal rate for (na2so4) is (0.028)g/min, and minimum value is (0.0084)g/min . fig. 11. effect of current at voltage (12v) and the concentration (20) g/l on material removal rate. fig.12 explains the effect of current (2,5,10) a, and voltage (20v), maximum material removal rate for nacl is (0.038)g/min, and minimum value is(0.01) g/min, and maximum removal rate for (na2so4) is (0.035)g/min, and minimum value is (0.0089)g/min. fig. 12 effect of current at voltage (20v) and the concentration of (30) g/l on material removal rate. conclusions the conclusions from experimental work are: 1increasing in concentration, current and voltage lead to increase in (ra) and (mrr), due to increase in electrochemical reaction that lead to increase in the ion exchange between the electrode and the working piece and the heat heba saad qasim al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 9199 (2019) 97 generated, leading to increased removal and roughness [9]. 2(na2so4) solution give surface roughness less than (nacl) solution in all levels, due to existence ion (-hso4) which appears as a product of the solution reaction as shown by the equations for k2so4, and acts as an acid and also 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[14] l. wang and j. n. gai, “study on optimization of machining parameters in electrochemical machining,” adv. mater. res. journal, vol. 476–478, no. 6, pp. 375– 378, 2017. )2019( 9199، صفحة ٤د، العد15دالخوارزمي الهندسية المجلجلة مهبة سعد قاسم 99 ئيالكهروكيمياتاثير محاليل كلوريد الصوديوم وكبريتات الصوديوم على مخرجات التشغيل **شكري حميد غضيب *هبه سعد قاسم ةالتكنولوجي ةالجامع تاج والمعادن/*قسم هندسة االن*،* gaithalaa468@yahoo.com :البريد االلكتروني * shukry-hammed@yahoo.com :البريد االلكتروني** ةالخالص عدن وتعتمد على عملية التشغيل الكهروكيميائي احدى عمليات التشغيل الالتقليدية حيث تستخدم التفاعل الكيميائي المرتبط بالتيار الكهربائي الزالة الم دعتُ طة غمرها سا) بو٣١٦ستنلس ستيل نوع ( ) ملم من طول الشغلة١الزالة ( سة عملية التشغيل الكهروكيميائيفي هذه الدرااستخدمت مبدا االنخالع االنودي . ) لتر من الماء المفلتر، العدة التي استخدمت من النحاس ومسافة ١) غم لكل (١٠٬٢٠٬٣٠بمحلول الكتروليتي من كلوريد الصوديوم وكبريتات الصوديم بتركيز ( ) امبير وتاثير ٢٬٥٬١٠هذه الدراسة ركزت على تغيير نوع المحلول االلكتروليتي وقيمة التيار التي استخدمت هي ( ،) ملم ٠٫٥الفراغ بين الشغلة والعدة ( نتائج المقارنة للتجارب العملية ان محلول كبريتات الصوديوم يعطي بينت ،) فولت على قيمة الخشونة السطحية ومعدل ازالة المعدن ٦٬١٢٬٢٠الفولتية بقيمة ( ) ٠٫٤٢٠) مايكرون واقل خشونة سطحية هي (٠٫٦٥٨واقصى خشونة سطحية هي ( ية اقل من محلول كلوريد الصوديوم ولكل المستوياتخشونة سطح ) مايكرون . كذلك يعطي اعلى معدل ٠٫٥٠٨) مايكرون واقل خشونة سطحية (٢٫٩١٣مايكرون بينما محلول كلوريد الصوديوم اعطى اقصى خشونة سطحية ( ) غم/لتر عند ٣٠) امبير وتركيز (١٠) غم/لتر عند (١٠٬٢٠) امبيروتركيز (٥) غم / لترعند (٣٠ن محلول كلوريد الصوديوم في المستويات (الزالة المعدن م .) فولت٦٬١٢( analysis of wave propagation in in detection of arterial diseas al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 5, no. 3 pp 16 22 (2009) analysis of wave propagation in detection of aorta dieses using lumps analysis a. m al-jumaily* a. salam al-ammri** * institute of biomedical technology / auckland university of technology/ auckland, nz ahmed.al-jumaily@aut.ac.nz ** department of mechatronics engineering/ al-khwarizmi college of engineering/ university of baghdad asalamalammri@yahoo.com (received 3 may 2009; accepted 6 august 2009) abstract in this paper a theoretical attempt is made to determine whether changes in the aorta diameter at different location along the aorta can be detected by brachial artery measurement. the aorta is divided into six main parts, each part with 4 lumps of 0.018m length. it is assumed that a desired section of the aorta has a radius change of 100,200, 500%. the results show that there is a significant change for part 2 (lumps 5-8) from the other parts. this indicates that the nearest position to the artery gives the significant change in the artery wave pressure while other parts of the aorta have a small effect. keywords: wave propagation, aorta, lumps analysis. 1. introduction several cardiovascular pathologies introduce variation in the radius and thickness of the aorta. plaques can cause severe arterial stenosis that leads to blood flow obstruction. the formation of fat deposits inside the aorta decreases the diameter and hinders, or even stops, the flow of blood. also, excessive artery enlargements caused by atherosclerosis can lead to aneurysms and its rupture may lead to the sudden death. all these variations affect the pattern of pressure waves. kevin p.c[1] extracted clinically useful information from the shape of the diastolic portion of the blood pressure. a simple third order, lumped parameter circuit model was proposed to characterize the wave shape change in terms of the mechanical features of the systemic arterial system. wen-shan duan, etal.[2] proposed an approach to understand the effect of arterial branching in large arteries. reflected and transmitted nonlinear waves at the arterial branching are analytically constructed from incident waves. jm padilla1,etal.[3] evaluated the relationship among blood pressure parameters and abpwv, and the relationship among abpwv, sidvp and ridvp in health subjects. aortic arterial stiffness is an independent predictor of cardiovascular risk. pulse wave velocity (pwv) is the most validated and universally accepted measure of arterial stiffness. the digital volume pulse (dvp) is an accurate and non-invasive method to obtain information on the pressure pulse waveform, and it provides two indexes: stiffness index (sidvp) which relates with large artery stiffness, and the reflection index (ridvp) which relates with vascular tone. sidvp has been previously correlated with cfpwv (carotidfemoral pwv), however, the inguinal location of the employed transducer provokes a strong psychological impact on the patients, which may reduce reproducibility. by contrast, measurement of abpwv (ankle-brachial pulse wave velocity) minimizes this psychological stress. temesgen markos kindo[4] measured the size of an aneurysm as the indicator of rupture potential and the necessity of medical intervention; the larger the aneurysm is the higher the risk of rupture is. it mailto:ahmed.al-jumaily@aut.ac.nz mailto:asalamalammri@yahoo.com a.m al-jumaily al-khwarizmi engineering journal, vol. 5, no. 3, pp 16 -22 (2009) 17 was observed that some large aneurysms stayed intact whereas smaller ones ruptured. kamran hassani etal.[6] showed that the decreasing of pressure along the aorta and renal artery lengths was due to the aneurysms and stenosis at the peak systole. the mathematical method demonstrated that compliances of the aorta sections and renal increased with the expansion rate of the aneurysms and stenosis. the results of the modelling, such as electrical pressure graphs, exhibited the features of the pathologies such as hypertension and were compared with the relevant experimental data. yannis papaharilaou[7] assessed the merit of a decoupled fluid structure analysis of aaa wall stress. anatomically correct patient specific aaa wall models were created by 3d reconstruction of computed tomography (ct) images. flow simulations were carried out with inflow and outflow boundary conditions obtained from patient extracted data. bedzinski [8] appointed experimentally the mechanical properties of abdominal aortic aneurysm (aaa) and abdominal aorta without pathological changes (naa), in both directions: longitudinal (naal, aaal) and circumferential (naac, aaac). the investigations included the analysis of the stress strain relationships of abdominal aortic aneurysm walls and unchanged abdominal aortas’ walls, as well as estimation of the relationships between them. r. cowling and j. soria [9] investigated the flow characteristics in abdominal aortic aneurysms using planar laser induced fluorescence (plif) for both steady and pulsatile flow conditions. for the pulsatile flow investigations a simple artificial waveform was used. under steady flow conditions two zones were identified; the first one is the bulk fluid through the core of the expansion, and the second one is a recirculation zone occupying the majority of the expansion. m. scotti [10] assessed the significance of assuming an arbitrary estimated peak fluid pressure inside the aneurysm sac for the evaluation of aaa wall mechanics, as compared with the non-uniform pressure resulting from a coupled fluid–structure interaction (fsi) analysis. in addition, a finite element approach was utilised to estimate the effects of asymmetry and wall thickness on the wall stress and fluid dynamics of ten idealised aaa models and one non-aneurysmal control. the results showed that the inclusion of fluid flow yields a maximum aaa wall stress up to 20% higher than that which is obtained with a static wall stress analysis with an assumed peak luminal pressure of 117 mmhg. josé f.[11] studied the influence of geometry and material anisotropy on the magnitude and distribution of the peak wall stress in aaas. three dimensional computer models of symmetric and asymmetric aaas were generated in which the maximum diameter and length of the aneurysm were individually controlled. they show a strong influence of the material anisotropy on the magnitude and distribution of the peak stress. results confirm that the relative aneurysm length and the degree of aneurismal asymmetry should be considered in a rupture risk decision criterion for aaas. peter c[12] showed that larger aneurysms increased risk of rupture because 1) they experience greater circumferential wall stress tending to expand the lumen, and 2) they are less distensible with a higher elastic modulus which indicates they have less reserve stretch capacity. 2. lumps analysis mathematical analysis leads to greater understanding and improving the diagnosis and treatment of cardiovascular diseases. this study is based on the work proposed by a.m al-jumaily and essa el-aklouk[13]. they developed a mathematical formulation to describe pressure wave propagations, reflection in elastic branching arteries and the transmission of pressure from the brachial artery through the arm soft tissue to the pneumatic cuff fig.(1). cuff soft tissue brachial artery model brachial artery area acoustic model fluctuations in the strain at the cuff outside wall cuff soft tissue brachial artery model invasive brachial artery pressure waveform fig. 1. flow chart of the acoustic model and the cuff-soft tissue-brachial artery model[13]. the material properties and geometry for the cuff, arm soft tissue, and the brachial artery used were adopted from the values reported by muriso et al [14-16]. the number of lumps that would accurately describe the wave propagation in the arteries is conducted from the experiment data of a.m al-jumaily al-khwarizmi engineering journal, vol. 5, no. 3, pp 16 -22 (2009) 18 westerhof et al [17]. the aorta was divided into 24 lumps of 0.018m length each while the subclavian and brachial arteries were divided into 16 lumps of 0.026m length each and the systolic cuff pressure was 120 mmhg. figures ( 2& 3 ) give the variation in thickness and radius of the aorta, and the subclavian-brachial arteries. fig. 2. the human aorta and the subclavian and brachial arteries. thickness variation[17]. fig. 3. the human aorta and the subclavian and brachial arteries radius variations. [17]. four feature points were extracted from the pressure contours to measure aortic stiffness. these feature points are (t1,t2) the time duration before the deflection marking the arrival of the incident and reflected waves respectively and (p1,p2) the peak of the first and second pressure deflection minus the diastolic pressure. the radial ai is used as an indicator for aortic stiffening and can be written as: ai = p2 / p1 and the time lag is written as: 2 1time lag t t the pressure contour has the same shape and contains all the feature points found in invasively measured brachial artery contours fig.(4). fig. 4. brachial artery pressure waveform for a healthy young adult. [13]. 3. results and discussion the effect of changing the aorta radius on the brachial artery pressure waveform and the strain on the external wall of the pneumatic cuff ranging from a healthy aortic stiffness (100%) to a diseased/aged aortic stiffness (200% and 500%) was shown in figures 2&3. to extract clinical useful information, the aorta is divided into six main parts, each part with 4 lumps.the radius of each part increased by 100%, 200%, 500% and keeping the radius of other parts unchanged. all other model parameters were kept constant. it is found that the increasing of radius by 200% will change the stiffness index by 1.2% for the first part (lumps 1-4), 5.5 % for the second part (lumps 5-8) and 1.8% for other parts of the aorta, while increasing the radius by 500 % will change the stiffness index by 3.35 for the first part, 10% for the second part and 4.6% for the other parts. the increasing of radius by 200% will change the time lag by 1.6% for the first part, 13 % for the second part and 3.3% for other parts, while increasing the radius by 500 % will change the time lag by 9.8% for the first part, 42.6% for the second part and 26% for the other parts. the strain on the pneumatic cuff outer wall .aortic thickness variation .brachial thickness variation .aortic radius variation .brachial radius variation a.m al-jumaily al-khwarizmi engineering journal, vol. 5, no. 3, pp 16 -22 (2009) 19 contour in figure 6 shows the main change for part 2 (lumps 5-8) of the aorta from the other parts. x(m) w a v e s p e e d ( c ) 100%200%500% 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 75 80 85 90 95 100 105 110 115 120 time (s) b ra c h ia l a rt e ry p re s s u re ( m m h g ) 100% 200% 300% 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 60 70 80 90 100 110 120 time (s) b ra c h ia l a rt e ry p re s s u re ( m m h g ) 100% 200% 300% 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 70 75 80 85 90 95 100 105 110 115 120 time (s) b ra c h ia l a rt e ry p re s s u re ( m m h g ) 100% 200% 300% (a) (b) (c) 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 70 75 80 85 90 95 100 105 110 115 120 time (s) b ra c h ia l a rt e ry p re s s u re ( m m h g ) 100% 200% 300% 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 70 75 80 85 90 95 100 105 110 115 120 time (s) b ra c h ia l a rt e ry p re s s u re ( m m h g ) 100% 200% 300% 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 70 75 80 85 90 95 100 105 110 115 120 time (s) b ra c h ia l a rt e ry p re s s u re ( m m h g ) 100% 200% 300% (d) (e) (f) fig. 5. brachial artery pressure waveforms at different part aortic radius for percent 100, 200 500, %, [a:1-4,b:5-8,c:9-12,d:13-16,e:17-20,f:21-24 lumps] 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.0513 0.0514 0.0514 0.0515 0.0515 0.0515 0.0516 0.0517 time (s) c u ff s tr a in 100% 200% 300% 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.0512 0.0513 0.0513 0.0514 0.0514 0.0515 0.0515 0.0516 0.0516 time (s) c u ff s tr a in 100% 200% 300% 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.0513 0.0514 0.0514 0.0515 0.0515 0.0515 0.0516 0.0517 time (s) c u ff s tr a in 100% 200% data3 (a) (b) (c) 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.0513 0.0514 0.0514 0.0515 0.0515 0.0515 0.0516 0.0517 time (s) c u ff s tr a in 100% 200% 300% 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.0513 0.0514 0.0514 0.0515 0.0515 0.0515 0.0516 0.0517 time (s) c u ff s tr a in 100% 200% 300% 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.0513 0.0514 0.0514 0.0515 0.0515 0.0515 0.0516 0.0517 time (s) c u ff s tr a in 100% 200% 300% (d) (e) (f) fig. 6. strain on the pneumatic cuff outer wall contours at different part aortic radius for percent 100, 200 ,500% , [a:1-4,b:5-8,c:9-12,d:13-16,e:17-20,f:21-24 lumps]. a.m al-jumaily al-khwarizmi engineering journal, vol. 5, no. 3, pp 16 -22 (2009) 20 table 1, showing the effect of aortic radius on the feature points of the brachial artery pressure contours, (aip), and time lag. radius % part (lumps ) p1 mmhg p2 mmhg ai% t1 (s) t2 (s) time lag (s) mean median mode std range 100% 1-4 116.7 111.5 95.5 .213 .274 .061 91.98 82.26 73.55 15.03 43.17 5-8 116.7 111.5 95.5 .213 .274 .061 91.98 82.26 73.55 15.03 43.17 9-12 116.7 111.5 95.5 .213 .274 .061 91.98 82.26 73.55 15.03 43.17 13-16 116.7 111.5 95.5 .213 .274 .061 91.98 82.26 73.55 15.03 43.17 17-20 116.7 111.5 95.5 .213 .274 .061 91.98 82.26 73.55 15.03 43.17 21-24 116.7 111.5 95.5 .213 .274 .061 91.98 82.26 73.55 15.03 43.17 200% 1-4 116.8 110.2 94.3 .218 .28 .062 91.98 83.17 79.91 14.81 43.19 5-8 116.7 105.4 90.3 .211 .28 .069 89.6 82.55 79.92 14.5 48.89 9-12 116.8 109.6 93.8 .213 .276 .063 91.98 83.61 79.9 14.67 43.06 13-16 116.7 109.6 93.8 .213 .276 .063 91.98 83.61 79.9 14.67 43.06 17-20 116.8 109.6 93.8 .213 .274 .063 91.98 83.61 79.9 14.67 43.06 21-24 116.8 109.8 93.8 .213 .274 .063 91.98 83.5 73.59 14.7 43.07 500% 1-4 116.8 108.1 92.5 .229 .296 .067 91.98 84.66 79.9 14.39 43.03 5-8 116.8 100.3 85.8 .212 .299 .087 89.07 84.4 66.65 13.99 50.02 9-12 116.8 106.4 91.1 .213 .29 .077 91.98 85.73 79.9 14.03 42.84 13-16 116.8 106.4 91.1 .213 .29 .077 91.98 85.73 79.9 14.03 42.84 17-20 116.8 106.4 91.1 .213 .29 .077 91.98 85.68 73.88 14.05 42.85 21-24 116.8 106.4 91.1 .213 .289 .076 91.98 85.68 73.88 14.05 42.85 4. conclusion the results show that the increase of radius will decrease the stiffness index and increase the time lag. it is found that there is a significant change brachial artery pressure waveforms and strain on the pneumatic cuff outer wall contours for part 2 (lumps 5-8) of the aorta from the other parts. the main changes are found in p2, t2 as indicated in figure 2 and table 1. the same conclusion is for s2 and t2 as shown in figure 3. the statistical parameters, the mean and range could be used as another good indication for these changes. this indicates that the nearest position of changing the radius to the artery gives the significant change in the artery wave pressure while other parts of the aorta have a small effect. acknowledgments we gratefully acknowledge the facilitated of ibtec, aut university, nz for using and modifying essa el-aklouk computer program 5. 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[4] temesgen markos kindo “mechanical degradation and remodelling of cerebral arteries”, technische university eindhoven ,eindhoven, october 2006 [5] josé f. rodríguez1 ,cristina ruiz,manuel doblaré, ”mechanical stresses in abdominal aortic aneurysms: influence of diameter, asymmetry, and material anisotropy”, journal of biomechanical engineering copyright © 2008 by asme april 2008, vol. 130 / 021023 [6] kamran hassani, mahdi navidbakhsh , mostafa rostami,” modelling of the aorta artery aneurysms and renal artery stenosis using cardiovascular electronic system”, biomedical engineering online 2007, 6:22 doi:10.1186/1475-925x-6-22 [7] yannis papaharilaou, john a. ekaterinaris, eirini manousaki, asterios n. katsamouris ,”stress analysis in abdominal aortic aneurysms applying flow induced wall pressure”,5th gracm international congress on computational mechanics limassol, 29 june – 1 july, 2005 [8] r. bedzinski., m. kobielarz m.s., s. szotek, ph.d., j. filipiak, ph.d. , j. janusz gnus m.d., w.hauser m.,”directional mechanical properties of abdominal aortain vitro study”,22nd anubia-adria symposium on experimental methods in solid mechanics,september 28 october 1, 2005 ,monticelli terme / parma italy [9] r. cowling and j. soria ,”flow visualisation through model abdominal aortic aneurysm”, fourth australian conference on laser diagnostics in fluid mechanics and combustion ,the university of adelaide, south australia, australia 7-9 ,december 2005 [10] m. scottia,christine jorge jimenezb, satish c. mulukc and ender a. finola,d,”wall stress and flow dynamics in abdominal aortic aneurysms: finite element analysis vs.fluid–structure interaction”,computer methods in biomechanics and biomedical engineering vol. 11, no. 3, june 2008, 301–322 ,mona abdolrazaghi, mehdi navidbakhsh and kamran hassani [11] f josé. rodríguez,cristina ruiz ,manuel doblaré ,gerhard a. holzapfel,” mechanical stresses in abdominal aortic aneurysms:influence of diameter,asymmetry, and material anisotropy”, journal of biomechanical engineering copyright © 2008 by asme april 2008, vol. 130 / 021023-1 [12] peter c. lin,”mechanical properties of aneurysms of the descending human aorta”,yale university school of medicine ,doctor of medicine,2007 [13] a.m. al-jumaily and essa el-aklouk,” an investigation into the acoustic response of the arteries”,mphil thesis, auckland university of technology (aut),auckland,2007 [14] m. ursino, , c. cristalli, , 1995, mathematical modeling of noninvasive blood pressure estimation techniques – part ipressure transmission across the arm tissue, asme journal of biomechanical engineering, 117:107-116. [15] m. ursino, cristalli, c., 1995, mathematical modeling of noninvasive blood pressure estimation techniques – part iibrachial hemodynamics, asme journal of biomechanical engineering, 117:117126. [16] m ursino, cristalli, c., 1996, a mathematical study of some biomechanical factors affecting the oscillometric blood pressure measurement, ieee transactions on biomedical engineering, 43:761-78. [17] n westerhof, bosman, f., de vries cj., et al , 1969, analog studies of human systemic arterial tree, journal of biomechanics, 2:121-143. http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=search&itool=pubmed_abstractplus&term=%22westerhof+n%22%5bauthor%5d http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=search&itool=pubmed_abstractplus&term=%22bosman+f%22%5bauthor%5d http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=search&itool=pubmed_abstractplus&term=%22de+vries+cj%22%5bauthor%5d 22 -16، صفحت 3، العذد 5هجلت الخىارزهً الهنذسٍت الوجلذ احوذ الجوٍلً (200 9) 22 تحلٍل تقذم الوىجاث فً تشخٍص أهراض الشرٌاى األبهر بىساطت تقسٍوه الى عذة هناطق ** عبذ السالم العاهري * احوذ الجوٍلً نٍىزلنذة / جاهعت اوكالنذ * ahmed.al-jumaily@aut.ac.nz جاهعت بغذاد / هنذست الخىارزهً /قسن هنذست الوٍكاترونٍكس** asalamalammri@yahoo.com الخالصت تم فٍ هذا انبحث وضع دراطت وظزَت نحظاب تغُز وصف انقطز نهشزَان األبهز فٍ عدة مىاطق وإمكاوُت تحظض هذا انتأثُز مه خالل قُاص انضغظ و تم . m 0.018 بطىل طتت مقاطع وكم مقطع َحتىٌ عهً أربعت أجشاء تم تقظُم انشزَان األبهز انً طتت أجشاء كم جشء مكىن مه . اإلجهاد فٍ شزَان انُد 5) انثاوٍ انمقطعنقد أظهزث انىتائج بان هىاك تأثُز واضح نشَادة انقطز فٍ .500,% 200,%100%فزض أن فٍ كم مقطع تحصم فُه سَادة فٍ انقطز عطٍ تأثُزا واضحا مه األجشاء ث انتٍ َحصم فُها االوتفاخ مه مىطقت انقُاصانمىطقت انقزَبت مه انشزَان مما َدنم األخزي انمقاطعمه انشَادة فٍ (جشء 8 .األخزي mailto:ahmed.al-jumaily@aut.ac.nz mailto:asalamalammri@yahoo.com <4d6963726f736f667420576f7264202d20312d313520cce3c7e120e6ddd1cc20e6d1dbcfc7c1> al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 15, no. 3, sptember, (2019) p. p. 115 design and optimization of a surface-mounted permanent-magnet linear synchronous motor with maxwell ansys jamal abdul-kareem mohammed* farag mahel mohammed** raghda'a ahmed a. ali*** *,**,***department of electromechanical engineering/ university of technology/ baghdad/ iraq *email: 50128@uotechnology.edu.iq **email: drfaragmahel@yahoo.com ***email: gadaahmad460@yahoo.com (received 1 august 2018; accepted 28 january 2019) https://doi.org/10.22153/kej.2019.01.005 abstract linear motor offers several features in many applications that require linear motion. nevertheless, the presence of cogging force can deteriorate the thrust of a permanent magnet linear motor. using several methodologies, a design of synchronous single sided linear iron-core motor was proposed. according to exact formulas with surface-mounted magnets and concentrated winding specification, which are relying on geometrical parameters. two-dimensional performance analysis of the designed model and its multi-objective optimization were accomplished as a method to reduce the motor cogging force using maxwell ansys. the optimum model design results showed that the maximum force ripple was approximatrly reduced by 81.24%compared to the original model with a smaller ripple coefficient of 0.22. likewise, the model was redesigned taking into consideration two cases; laminated core and solid core. it was found that the error between the analytical and numerical results of the output force did not exceed 0.0967%. keywords: ansys, cogging force, linear motor, optimal design. 1. introduction permanent magnet linear motors (pmlms) are used in wide industrial applications; particularly for high positioning accuracy of concerned implementations. the linear motors (lms) are mainly based on the electromagnetic concept where they delivere direct linear movement without using gears, cams, belts or other mechanical accessories. this is when the mechanical motion synchronizes the magnetic field. the pmlsms can be classified into categories: flat or tubular, single sided or double sided, slotted or slot-less, air cored or iron-cored, and longitudinal flux or transverse flux. the lm consists of stator and the translator. since, it can present direct linear motion with no need for any rotation to translation conversion of equipment; this leads to simplifying system structure and improving system efficiency [1]. on the other hand, the more predominant nonlinear effect of linear motors is force ripples (detent and reluctance forces) [2]. the detent (or cogging) force is generated by the attraction of the magnets to the lm's core. this force is produced even the winding current is absent. the force demonstrates a periodic relationship with regard to the position of the translator relative to the permanent magnets (pms) mounted on the stator [3]. moreover, the reluctance force is generated by the mutation in the winding self-inductance with respect to the position between the translator and stator [4, ٥]. hence, the cogging forces generally cause an undesired vibration and noise; depending on the thrust magnitude [6]. in order to minimize the force ripple, different methods in the literature were developed. one of the most effective methods is the arrangements of jamal abdul-kareem al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 115 (2019) 2 the pms. thus, it must be optimized to reduce the cogging force, which is more effective than reluctance force as represented by lim et al. [7]. also, the method could be conducted by adding some parts as presented by baker et al. [8]. it's found that adding a flux gathering ring (fgr) to the outer stator teeth of a linear tubular generator could be an effective method to reducing the end effect. hence, the cogging reduction happens as resultant. chung et al. [9] proposed designing and analyzing a flux reversal linear synchronous motor (frlsm). three various design parameters were investigated and compared in motor characteristics e.g, back-emf, detent force, normal force, thrust, and phase inductance by using maxwell ansys. the investigation greatly showed low force ripple and good thrust force linearity via pms' skewing and three-phase sinusoidal control. cao et al. [10] investigated the effect of some leading design parameters (mover tooth width, the slot open width the width of the slot under pm, mover height and the motor stack length) on the force performance of a complementary and modular linear flux-switching permanent-magnet (lfspm) motor. that is using finite element method (fem). jalal et al. [11] presented the fea optimization techniques followed by development of a matlab/simulink model to investigate the effects of electrical machine inductance and the combined electromagnetic loading of the machine on the resulting force and cogging force. palomino et al. [12] proposed a technique to combine the fem and the statistical regression, which permit to implement the optimal skew angle of the pm. that causes a greater reduction of force ripple with the minimum thrust diminution. ghasime [13] adopted a magnet segmentation method to reduce the cogging torque. wheras, each surface pm was split into eight parts with symmetrical structure and equal angular widths. the angular gaps between them were utilized for reducing a number of optimization parameters. lazov and uzunov [14] used two methods to reduce the detent force in one innovative pmlsm for 2d laser marking system. two additional end teeth with chamfers in the magnetic circuit of the movable part were used while the other method modified the teeth of the ferromagnetic core with different lengths. this paper suggests an optimization method to estimate the optimum dimensions of the pmlsm based on regular steps with the aid of the maxwell ansys simulation. the optimum dimensions required are the magnet length, magnet width, magnet height, air gap length, motor length at zdirection and the motor ends' width. 2. design procedure the pmlsm is a linear motor where the mechanical motion is synchronizing the magnetic field. the pmlsms can be classified into flat or tubular, single sided or double sided, slotted or slot-less, air cored or iron-cored, and longitudinal flux or transverse flux. in this paper, the design of a single-sided pmlsm with slotted armature core and surface pms is proposed. a structure model of a three-phase flat type single sided pmlsm according to the maxwell ansys is depicted as in fig. (1). 1. slotted armature core, 2. surface pms, 3. three-phase windings, 4. yoke,5. dummy slot. fig. 1. 3d model of the proposed pmslm. jamal abdul-kareem al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 115 (2019) 3 the core is composed of 13 slots and 13 teeth, 12 slots are filled with single layer concentrated three phase coil windings in a laminated 1010 steel core [15] as a solid core. each phase in the motor has four slots. these magnetic cores may be made of thin laminations in order to minimize the eddy currents flowing through them. as for all electrical machines, the core losses are composed of hysteresis losses and eddy current losses. the specifications of pms (ndfeb, class n42sh) [16] used in the motor design are listed in table 1. table 1, ndfeb permanent magnet specifications. b(mt) h(ka/m) bh_max(kj/m3) tmax(oc) 1280-1320 >= 1672 320-343 150 generally, thrust production in the pmlsm is restricted by electrical and magnetic sources. electrical source depends on the motor coils current. according to lorentz law [17]: �⃗ � ��⃗ � ��⃗ (vector version) and f= ibl sinθ (strength only) ...(1) at the same time, for magnetic components, the magnetic flux density and inductance effect on the thrust. while the flux of the pms and coils effect on the magnetic flux density and inductance. this leads to generate a sequence of attracting and repelling forces between the salient poles and the pms, expressed by a thrust force in the translator [18]. fig. 2 depicts the working principle of the designed linear motor. fig. 2. working principle of a three-phase pmlsm [19]. as the armature moves, an emf is induced in the stator windings. by differentiating the pm flux of the phase winding with time, a no-load rms voltage ef is excited. ef is excited by the pms' flux and induced in each phase of the armature winding, it can be given as [17]: � 2� ����� …(2) where: � � � ������������ℜ� ℜ��⁄ ! ⁄ " ���� " ���ℜ��/ℜ�� $� ℜ��⁄ %& !'"&( …(3) ) � 1 + � ℜ�� ,2 ℜ./ +0.5 ℜ�34 …(4) � � 2)ℜ5 + 2 6./ +0.5ℜ�3 …(5) 7 � 2ℜ89 + 0.5ℜ�3 …(6) : � 1 + 4 ℜ� ℜ�� + ℜ<= ℜ�� …(7) the magnetic circuit of an lsm with surface pms as illustrated in the equivalent magnetic circuit is shown in fig. 3. jamal abdul-kareem al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 115 (2019) 4 fig. 3. equivalent magnetic circuit of a lm with surface pms [17]. while, the magnetic flux linked with the armature winding may be given as: � � � ������������ℜ� ℜ��⁄ (" ���� " ���ℜ��/ℜ�� $� ℜ��⁄ %' !'"&( …(8) the relation between the velocity and frequency represented by [17] υs= 2τƒ …(9) the frequency could be estimated using eq. (9), is found to be equal to 17.36hz. that is according to the parameters listed in table 2 with the following design parameters: fmax = 350n mtranslator ≈ 6.6kg mload = 17kg υmax = 1m/s amax = 1.5m/s2 table 2, lm base line design parameters [20]. lm (mm) ττττ (mm) ⍵⍵⍵⍵p (mm) 288 28.8 24.32 based on these dimensions and assuming initial teeth lengths and pm volume followed by applying a special algorithm with multiple iterations to obtain the final main design dimensions of the pms and the geometric dimensions of a single stator slot illustrated in fig. 4. in the case of using semi-closed slot in the stator core, the detent force depends on the slot aperture width because of the minimizing effect on the slot harmonic components [21]. fig. 4. dimensions in mm of a single stator slot. the armature winding resistance as a function of the winding parameters, dimensions, and electric conductivity can be represented by [17]: ?� � � $@´₁ c/d " e/f% g₁ h ij₁kjkl …(10) in the case of salient pole synchronous motor, the d-axis and q-axis synchronous reactances, respectively can be expressed as: mno � m� + mko and mnp � m� + mkp …(11) here, x1 = 2�fl1 is the armature leakage reactance, and xad and xaq are the d-axis and qaxis armature reaction reactance’s, respectively [21] which are calculated as follows: mko � � omk � 4q�rs $g/tj/%< uv w @x 5´ � o …(12) mkp � � pmk � 4q�rs $g/tj/%< uv w @x tycz�-[ 5[ � p …(13) where \´ ≈ �' n̂k_\ + ℎ9 raab3⁄ is the d-axis equivalent air gap, ksat>1 i and ksatq≈ 1. jamal abdul-kareem al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 115 (2019) 5 demagnetization curve of the pm is sensitive to temperature changes. both br and hc reduce as the magnet temperature elevates [17]: �a � �3�c[1 + ef �cc $g89 − 20%]and i3 � i3�c[1 + ej �cc $g89 − 20%] …(14) where bc20 and hc20 are the flux density and coercive force of the pm at 20oc, and k&< 0 and kl< 0 are the temperature coefficients in %/oc for br and hc, respectively. the relative recoil magnetic permeability at pm temperature g89of 50oc can be calculated as: raab3 � &m nol= …(15) where µ rrec = 1.161. the following equations are the rms d-axis and q-axis armature currents as a function of v1, xsd, xsq, r1, ef, and δ as shown in fig. 5. �ko � p/�qz[ 3snr –t/ nuvr � wxqz[ qz� qz[ " t< and �kp � p/$t/ 3snr –qz� nuvr%� wxt/ qz� qz[ " t< …(16) �k � y�z{� + �z|� …(17) fig. 5. full phasor diagram of a lsm [14]. the peak line current density of the armature or the specific electric loading is determined as: )} � }/√� g/�� vw …(18) the input power pi delivered to the armature winding is given by: �u � q����k cos ∅ …(19) the copper losses in the core windings is: �∆�� � q��z�?�. the electromagnetic power (pelm) and thrust force (fdx), respectively can be given as [17,22]: �be} � }/[p/$t/3snr"qz�nuvr%�wxt/] $qz�qz[ "t<%< � ����mnp���� − ?���� �mno−mnp + �mnomnp + ?� − mnp�mno − mnp � …(20) �o� � 8f�� �z …(21) so, theforce ripple coefficient kr could be calculated by [23]: kr = $�}k�� �}uv% �k�b …(22) 3. finite element simulation a. solving and post-processing finite element method is one of the most accepted and widely used tools for the solution and optimization of linear and nonlinear partial differential equations [24]. in the current work, the analysis was performed using maxwell ansys that ignored end windings due to using 2d model. the structure parameters of the motor were presented. the solution was divided into two stages, load and no-load transient magnetic solution. time-stepping fea method depending on maxwell equations was applied for analyzing and optimizing the magnetic and force characteristics of the lm. in the process of solving nonlinear transient magnetic problem, the calculated values of voltage v1 is 45v (at load) and frequency f= 17.36hz, whereas the solution would be divided into 36 steps with 0.0016sec time period at 0.0001 nonlinear residual using backward euler time integration method. mover mesh of the original motor is illustrated in fig. 6 where the mesh should be dense enough to minimize the error calculation, whereas the model was designed with three regions of meshing. each region contains 1200 elements. jamal abdul-kareem al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 115 (2019) 6 fig. 6. mover mesh of one region, 4 slots (x & y are the length and the height of the stack, respectively) at position = 4.5mm with respect to the stator, time = 0.0045 sec from initial position. b. magnetic field distribution on no-load case, considering the axial symmetry of the pmlsm, the designed motor was simplified to a 2d axial symmetry model in cartesian coordinates ignoring core losses. an irregular distribution of the current density in the conductor was considered. the distribution of the magnetic lines is depicted as shown in fig. 7. various shades of rainbow color denoted magnetic flux density values at time equal to 0.0032 sec plus the leakage flux inside the slots was clearly noticed. fig. 7. distribution of linkage magnetic field lines as closer section with the leakage magnetic field lines (x: motor height, y: reaction rail (yoke) length). furthermore, the instantaneous pm flux linkages and induced back emf waveforms at noload magnetic field solutions were obtained as shown in figs. 8 and 9, respectively. it was observed that the waveform of the flux linkage was approximate sinusoid. since there was no harmonic magnetic flux, which might be induced by the current at the load case. the pms flux waveforms were three phase symmetrical, i.e. they had the same magnitude with 120 electrical degrees shifting. this is a fundamental requirement of three-phase motor design. unlike the flux linkage, the back emf has irregular sinusoid. jamal abdul-kareem al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 115 (2019) 7 fig. 8. 3-phase flux linkage waveforms of the original designat no-load case. fig. 9. 3-phase induced back emf waveforms of the original design at no-load case. figure 8 shows that the maximum value of flux linkage on one coil is ≈ 0.46wb, while the rms value of the back emf, ef is about 34.63v. considering that the phase winding consisted of one active coil at any instant. the comparison of values above with the analytical calculations where the pm flux was φf = 0.4508wb (eq. (3)) and the back emf, ef= 34.3v (eq. (2)) shows small error between them. representation of the magnetic field density graph can be illustrated in fig. 10. it can be noticed that the flux lines move in the transverse direction forming closed loops between each other. fig. 10. magnetic field density as a vector in air-gap, core, back-iron along with magnet at position = 4.5 mm, time = 0.0045sec from initial position. jamal abdul-kareem al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 115 (2019) 8 c. simulink design optimization of the pmlsm model with and without core losses figure 11, shows the pmlsm model's thrust force at load moving 2� distance to +x direction and the armature current waveforms for the original model with three-phase ac voltage source, neglecting the core losses of the laminated core. the thrust force with rms value was found to be 350.3387n (with 0.9176 ripple coefficient) at ia≈4.32a. the thrust ripple depended on the field harmonic produced by the magnets (in the air gap) in addition to current harmonics. (a) (b) fig. 11. the simulation results; (a) thrust force,(b): 3-phase currents. the optimization was accomplished based on the model in sec. 2. fig. 12, shows the results of two cases based on maxwell ansys analysis to predict best dimensions that lead to minimum cogging force at no load case. in fig. 12-a, the analysis was accomplished based on table 3-a (first design). the analysis has shown that the maximum cogging force was decreased by 73.9%. fig. 12-b presents the second design results, which were done with another set of constant values. the cogging force results have decreased by 77.43%.the second design gave the best percentage value of the cogging force reduction. fig. 12-c represents the ends widths effect on the cogging forces varation of second design at constant values of (em=5, g=1.5 and hm=3) with ends width of table 3-b. the results showed that, using 2.5mm end length led to 81.24% reduction in cogging force. table 3, (a) fist case and (b) second case of optimization procedure (all dimensions in mm). (a) parameters iterations g1 hm ωp&l´1 first 1 5 24.32 95 18.66 95 12.32 95 24.32 85 18.66 85 second 1.5 3 12.32 85 24.32 75 18.66 75 12.32 75 (b) one of the ends length em (iterations) constant parameters 0.25 g1 = 1.5 1.4375 hm = 3 2.625 ωp = 12.32 3.8125 l´1 = 75 5 lm = l´1 = 75 jamal abdul-kareem al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 115 (2019) 9 (a) cogging forces at constants (em=5, g =1 &hm=5) mmwith different values of ⍵⍵⍵⍵p&l´₁₁₁₁. (b) cogging forces at constants (em=5, g=1.5 &hm=3) mm at different values of⍵⍵⍵⍵p &l´₁₁₁₁. (c) cogging forces at diffirent ends widths with best dimentionsof step (b); (g=1.5, hm=3, ⍵⍵⍵⍵p=12.5 &l´₁₁₁₁=75) mm . fig. 12. best dimentions of the optimum value of the cogging force. table 4 clarifies the orginal model dimensions and parameters plus the optimum design results from the steps above. that is to find the optimum output thrust as illustrated in fig. 13 for the load case using maxwell ansys. the rms value of the output force was found to be equal to 320.4833n at the mean value for the rms motor currents of ia =3.555a. the output force might be equal to 320n at mload = 17kg and optimum mtranslator ≈ 4.75kg. it could be seen that the thrust ripple reduced effectively for the optimal designed motor case. in fact, the optimized motor suffered from thrust ripple twice less than that for the original model. therefore, the rms input voltage of three phase had to be increased by 11.56v to compensate the lost thrust caused by reducing the pm volume. jamal abdul-kareem al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 115 (2019) 10 table 4, the major dimensions and parameters of the two design models; calculated and optimal. (a) thrust force as a function of time at rms current = 3.555a with optimum parameters. (b) 3-phase of 2d simulated currents with optimum parameters. fig.13. motor performance with optimum parameters. symbols dimensions and parameters quantities calculated optimum pin input power (w) 402.7 411.21 v1 rated voltage (v) 45 56.568 ia armature current (a) 4.3 3.555 f magnetic field frequency 17.36 17.36 n1 number of turns of coil winding/phase 280 480 g1 air gap length (mm) 1 1.5 em one of the ends length (mm) 5 2.5 r1 armature winding resistance/phase (ω) 0.95 2.48 l´1& lm length of the laminated stack at z direction (mm) 95 75.2 dw diameter of copper wire (mm) 1.3 0.95 ωp pm width (mm) 24.32 12.5 hm pm height (mm) 5 6 hc2 stator height (mm) 8 8 x1 armature leakage reactance (ω) 1.8723 …. xad d-axis synchronous reactance (ω) 1.0228 …. xaq q-axis synchronous reactance (ω) 0.86023 …. kw winding factor [25] 0.966 …. δ load angle (degrees) 8.85 …. ∆pcu copper losses (w) 52.7 91.21 jamal abdul-kareem al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 115 (2019) 11 the core loss could affect the machine flux linkages. as these measurements were done at low speed, consequently the core loss component was sort of small where it was equal to (25.568w) as shown in fig. 14-a and the output force at fig. 14-b was (253.4n) at mean value of the rms motor currents of ia = 5.29 a. therefore, errors in the flux linkage computation were small since magnetic losses were caused by harmonic main flux and harmonic leakage flux [26]. (a) (b) (c) fig. 14. (a) iron losses of optimum solid core, (b) output thrust in this case and (c) 3-phase currents. thrust force constants, force ripple coefficient and the efficiency percentage [27] results are illustrated in table. 5. the greater value of the force constant (kf = fdx/ ia) [28] led to least thrust ripple krand highest efficiency which represented the best model. variant results were observed in the model's kf-rms values. this disparity was located due to a few reasons whereas two of them jamal abdul-kareem al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 115 (2019) 12 were convergent unlike the rest. the convergence of the first two models' values was related to the error between the exact and the analytical equations. while the increment of the third model was due to applying the optimization method to enhance the performance, which is the goal of this paper. on the other hand, loss consideration in the fourth model caused the kf-rms value to decrease. however, the ripple coefficient was equal to 0.319 that was considered an acceptable value to the practical designs in comparison with rest of the models that contain high efficiency or better ripple coefficient but remain a virtual design. table 5, force constant values, ripple coefficient, and efficiency models kf-max (n/a) kf-min(n/a) kf-rms(n/a) ia(a) kr efficiency % 1-analytical model …… …… 81.395 4.3 …… 86.91 2-simulated model 129.65 59.814 81.096 4.32 0.93 86.92 3-optimal model 108.257 88.963 90.15 3.555 0.22 77.82 4-optimal model with losses 58.631 43.73 47.845 5.2962 0.319 64 4. conclusions towards enhancing the performance of the single sided pmlsm, a primary structure of 10/12 pole-slot three phase synchronous single-sided linear motor has been designed and modeled using 2d fea simulation whereas a maxwell ansys has been employed. the following conclusions can be presented: 1. the design achieves optimum motor performance with minimum thrust ripple coefficient of 0.22 and thrust force of 320.4833n at rms load current of 3.555a wherekf-rms of 90.15. 2. the optimized motor gives a thrust ripple twice less compared to the original model. 3. some loss of thrust force is caused by the reduction in the pms volume. 4. the core losses are introduced as a second case with a laminated core for the optimum model producing a thrust ripple coefficient of 0.319 and thrust force of 253.4 n at rms load current of 5.2962a where kf-rms of 47.845. 5. the analytical model and numerical simulations results show a good agreement with maximum error not exceeding 0.0967%. notation a, b, c, d constants based on magnetic circuit of an lsm with surface pms amax motor acceleration at the starting ap the number of parallel current path aw the number of parallel conductors b magnetic field density bh_max maximum energy production fad the d-axis armature reaction mmf fave , fmin average output thrust and minimum thrust, respectively fm the equivalent mmf produced by one pole of the pm fmax , fdx thrust force f the input motor frequency \q the q-axis air gap length h magnetic field strength hm pm heightof a single pole k1r the skin effect coefficient ksat the saturation factor of the magnetic circuit ksatq the saturation factor in the salient pole excitation system kc the carter's coefficient for the air gap kw the armature winding coefficient l´₁ the laminated stack length li the stator core effective length lm pm length lm motor length l1e the mean length of a single end connection m1 the number of motor phases mload load mass mtranslator translator mass n1 the number of stator winding turns q1 the number of slots per pole ℜ�3 the reluctance of the armature core (yoke) per pole pitch ℜ�3 the reluctance of the reaction rail core (yoke) per pole pitch ℜ5 the reluctance of the air gap ℜe5 the reluctance of the air gap leakage flux ℜe} the reluctance for the pm leakage flux ℜ89 the reluctance of the pm ℜ_ the reluctance of a single tooth sw1 the armature conductor cross jamal abdul-kareem al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 115 (2019) 13 section tmax maximum working temperature υmax motor velocity greek letters δ the load angle between the terminal motor phase voltage v1 and ef φf the magnetic flux produced by the pm ∅ the motor power factor angle, the phase angle between v1 and ia øa, øc, øc the magnetic flux of three phases a, b and c, respectively ⍵p pm width θ the angle between the field direction and the conductor direction µo the free space magnetic permeability σ the electric conductivity of a conductor at an operating temperature τ pole pitch 5. references [1] a. basak, permanent-magnet dc linear motors. oxford, clarendon press, 1996. [2] g. otten, theo j.a. de vries, a.m. rankers, e.w. gaal, ''linear motor motion control using a learning feedforward controller,'' ieee/asme transactions onmechatronics, pp.161-70, 1997. [3] k.k. tan, t.h. lee, h.f. dou, s.j. chin and s. zhao, ''precision motion control with disturbance observer for pulsewidthmodulated-driven permanent-magnet linear motors,'' ieee transactions on magnetics, vol. 39, no. 3, may 2003. [4] c. rohrig, ''identification of force functions for permanent magnet linear synchronous motors,'' in proceedings of the 5th international symposium on linear drives for industry applications, ldia2005, kobeawaji, japan, september 25-28, 2005. pp.536-539. [5] d. wu , a. s. jalal and n. baker, ''a coupled model of the linear joule engine with embedded tubular permanent magnet linear alternator,'' energy procedia vol. 105, pp. 1986 – 1991, 2017. [6] i.i. abdalla, z.a. anwarudin, a.r.t. firmansyah, a.r. a. aziz and m.r. heikal, ''cogging force issues of permanent magnet linear generator for electric vehicle,'' j. electrical systems, pp. 489-502, 2017. [7] k.c. lim, j.k. woo, g.h. kang, j.p. hong, and g.t. kim, ''detent force minimization techniques in permanent magnet linear synchronous motors'', ieee transactions on magnetics, vol. 38, no. 2, 2002. [8] n. j. baker, r.m. korbekandi, a. sa. jalal and d. wu, ''performance of a tubular machine driven by an external combustion free piston engine,'' 9th international conference on power electronics, machines and drives (pemd 2018), liverpool. uk, 2018. [9] s.u. chung, h.j. lee, and s.m. hwan, ''a novel design of linear synchronous motor using frm topology,'' ieee transactions on magnetics, vol. 44, no. 6, jun.2008. 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[14] l. lazov and p. uzunov, "minimizing the detent force in permanent magnet linear synchronous motor for driving of 2d laser marking table," in environment technology and resources: proceedings of the11th international scientific and practical conference, vol. 3, rezekne, latvia 2017, pp. 174-178. [15] aisi 1010 steel data sheet, authorized precision ball and roller distributors in the uk, available on: https://simplybearings.co.uk/shop/files/1010. pdf [16] sintered neodymium iron boron (ndfeb) magnets – eclipse magnetics, available on: jamal abdul-kareem al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 115 (2019) 14 https://www.eclipsemagnetics.com/media/wy siwyg/brochures/neodymium_grades_data.pd f [17] j.f. gieras, z.j. piech, b.z. tomczuk, linear synchronous motor-transportation and automation systems, 2nd edition, crc press, taylor & francis, florida, 2000. [18] s.a. nasar and i. boldea, linear electric motors: theory, design and practical applications,1st edition, prentice-hall, 1987. [19] g. otten, t. j.a. de vries, j. v. amerongen, a. m. rankers, and e. w. gaal, ''linear motor motion control using a learning feedforward controller,'' ieee/asme transactions on mechatronics, vol. 2, no. 3, pp. 1083–4435, september 1997. [20] x. wang, p. wang and x.xu, ''magnetic field analytical calculation of the permanent magnet synchronous linear motor with fractional slot concentrated windings,'' in proceedings of 17thinternational conference on electrical machines and systems, icems2014, hangzhou, china, oct. 22-25, 2014. [21] k.c. lim, j.k. woo, g.h. kang, j.p. hong and g.t. kim, ''detent force minimization techniques in permanent magnet linear synchronous motors,'' ieee transactions on magnetics, vol. 38, no. 2, 2002. [22] h.a. toliyat and g.b. kliman, handbook of electric motors,2nd edition, taylor & francis group, llc, 2004. [23] a. l. shuraiji, z.q. zhu, and q.f. lu, ''a novel partitioned stator flux reversal permanent magnet linear machine'', in proceedings of 2015 tenth international conference on ecological vehicles and renewable energies (ever), 2015. [24] f. al-shamma, f. f. mustafa and s. m. saliman, ''an optimum design of cam mechanisms with roller follower for combined effect of impact and high contact loads,'' al-khwarizmi engineering journal, vol. 6, no. 4, pp. 62 – 71, 2010. [25] c. svihus, investigation of interior permanent magnet machines with concentrated windings for high dynamics applications, msc. thesis, christian sihus spring 2015. [26] a.m. saleh and a.th. radhi, ''effect of harmonics on a solid-rotor induction motor,'' journal of engineering, vol. 12, no. 1, pp. 199-217, march, 2006. [27] a.s.j. abdi, ''steady state performance investigation of a three phase induction motor running off unbalanced supply voltages,'' al-khwarizmi engineering journal, vol. 7, no. 3, pp. 1 – 12, 2011. [28] q. lu, j. shi, x. huang, y. fang and y. ye, ''performance of partitioned primary linear switched flux pm machines,'' ieee, pp.2486-2491, 2016. )2019( 115، صفحة 3، العدد15دجلة الخوارزمي الهندسية المجلم جمال عبد الكريم محمد 15 على َبتتَصميم وتحقيق التصميم االمثل للمحرك الخطي التزامني ذو المغناطيس الدائم الُمثّ السطح باستخدام برامج ماكسويل أنسزز ***علي رغداء أحمد عبد فرج محل محمد** الكريم محمد*جمال عبد العراق /قسم الهندسة الكهروميكانيكية / الجامعة التكنولوجية / بغداد*** ،**،* 50128@uotechnology.edu.iq:البريد االلكتروني * drfaragmahel@yahoo.com :البريد االلكتروني ** gadaahmad460@yahoo.com :البريد االلكتروني *** الخالصة ب المغناطيسية التجاذالتي تتطلب حركة خطية. على الرغم من ذلك ،فإن وجود قويزات في العديد من التطبيقات ميوفر المحرك الخطي العديد من الم تزامن أحادي ك خطي مالتي تشابه قوى الترس الميكانيكية يمكن أن يتسبب في تدهور قوه الدفع في محرك خطي ذي مغناطيسي دائم. لذلك تم تقديم محر ت رات المتغيرالى تأثيبوجود اللف المتمرّكز وتمثيله طبقا لصيغ الدفع التحليلي مستندة ع الجانب في هذه الورقة مصمًما بمغناطيس مثبت على السطح ه الظاهرةلتعامل مع هذلنهجيات . تبعا لذلك، تم تنفيذ العديد من الممالهندسية مثل، تشكيلة اخدود الملف، طول الفجوة الهوائية، وارتفاع المغناطيس الدائ رك ة التجاذب المغناطيسي للمح) للنموذج المصمم والتحسين متعدد األهداف الخاص به طريقة لتقليل قو٢dداء ثنائي األبعاد (يتم انجاز تحليل األالمؤذية. مقارنة % ٨١٫٢٤ . تُبين نتائج تصميم النموذج المثالي بأّن التموج الحاصل في قوة الدفع القصوى تقل بحواليmaxwell ansysباستخدام برنامج ن؛ القلب المرّقق (ذو . أيضا، تّم أخذ خسائر القلب الحديدي بنظر االعتبار ولحالتي٠٫٢٢ألصلي (قبل التطوير) وبأصغر معامل تموج هو مع النموذج ا في المحرك ةلدفع الخارجااب قوة الشرائح) والقلب الُصلب وقُورنت النتائج في الحالتين. لقد وجد بأن خطأ نتائج التصميم بين الطرق التحليلية والعددية لحس .٠٫٠٩٦٧ال تتجاوز 5971 al-khwarizmi engineering journal,vol. 12, no. experimental and numerical study solar chimney performance aseel k. shyaa maryam muayad abbood *,**,***department of mechanical engineering *** (received http://dx.doi.org/10.22153/kej.2016.05.002 abstract there have been many advances in the solar chimney power plant since 1930 and the first pilot work was built in spain (manzanares) that produced 50 kw. that needs to be investigated to enhance the perfor enhance the velocity towards the chimney to maximize design velocity. in this experimental and numerical study, the reduction area of solar collector was investigated. the reduction are the absorbing plate (h1=3.8cm, h2=2.6cm and h3=1.28cm). the numerical study was performed using ansys fluent software package (version 14.0) to solve the height of reduction area to the design velocity (velocity move the blade of turbine at inlet in the chimney). the results showed that the third height (h3=1.28cm) gives the best result because when decreasing the height between th glass cover and absorbing plate, the area between them decreased and the design velocity increased then the efficiency of solar chimney model was increased. keyword: solar chimney, collector, mathematical modeling, numerical simulation, enhance performance 1. introduction the solar chimney power plant consists of a solar air collector, a solar chimney and a turbine coupling with generator [1] .the mean aim from manufacture the solar chimney power plant to convert the power of solar radiation energy to thermal energy and by the rotation of turbine convert to mechanical energy and put the electric station in this to generate the electrical en that’s used in different way in the life. the solar chimney power plant is shown in figu change of area is use to generating swirl flow inside solar collector of the solar chimney. mark[2] the height of the roof inlet was adjustable, so that the ratio of flow areas between 1 khwarizmi engineering journal,vol. 12, no. 4, p.p. 5971 (2016) numerical study of collector geometry effect solar chimney performance shyaa* rafea a. h. albaldawi** maryam muayad abbood*** department of mechanical engineering/ university of al-mustansiriyah aseelkhshyaa@yahoo.com :maile* **email: rafa_a70@yahoo.com memomoaed@yahoo.com email:*** (received 18 february 2016; accepted 5 may 2016) http://dx.doi.org/10.22153/kej.2016.05.002 advances in the solar chimney power plant since 1930 and the first pilot work was built in spain (manzanares) that produced 50 kw. the solar chimney power plant is considered of a clean power generation that needs to be investigated to enhance the performance by studying the effect of changing the area of passage of air to enhance the velocity towards the chimney to maximize design velocity. in this experimental and numerical study, the reduction area of solar collector was investigated. the reduction area that mean changing the height of glass cover from the absorbing plate (h1=3.8cm, h2=2.6cm and h3=1.28cm). the numerical study was performed using ansys fluent to solve governing equations. the aim of this work was to study the height of reduction area to the design velocity (velocity move the blade of turbine at inlet in the chimney). the results showed that the third height (h3=1.28cm) gives the best result because when decreasing the height between th glass cover and absorbing plate, the area between them decreased and the design velocity increased then the efficiency solar chimney, collector, mathematical modeling, numerical simulation, enhance performance the solar chimney power plant consists of a solar air collector, a solar chimney and a turbine [1] .the mean aim from manufacture the solar chimney power plant to convert the power of solar radiation energy to thermal energy and by the rotation of turbine convert to mechanical energy and put the electric station in this to generate the electrical energy that’s used in different way in the life. the solar figure (1). the change of area is use to generating swirl flow inside solar collector of the solar chimney. mark[2] the height of the roof inlet was t the ratio of flow areas between roof inlet and roof outlet could be varied. the reduction in pressure at the point of reduction area is come from the reduction in area which will draw the air flow to the region of area after the reduction. this techniqu increase heat transfer between the air flow and absorber plant and between air flow and glass cover, and to increase air velocity constructed four small-scale physical models of the solar chimney were constructed. the heigh the roof inlet was adjustable, so that the ratio of flow areas between roof inlet and roof outlet could be varied. in addition, there were plants with constant cross sectional area towers and a plant with a divergent tower. also there was one plant with a novel roof shape. results indicate that the al-khwarizmi engineering journal (2016) collector geometry effect on ** mustansiriyah advances in the solar chimney power plant since 1930 and the first pilot work was built in the solar chimney power plant is considered of a clean power generation mance by studying the effect of changing the area of passage of air to enhance the velocity towards the chimney to maximize design velocity. in this experimental and numerical study, the a that mean changing the height of glass cover from the absorbing plate (h1=3.8cm, h2=2.6cm and h3=1.28cm). the numerical study was performed using ansys fluent . the aim of this work was to study the effect of change the height of reduction area to the design velocity (velocity move the blade of turbine at inlet in the chimney). the results showed that the third height (h3=1.28cm) gives the best result because when decreasing the height between the glass cover and absorbing plate, the area between them decreased and the design velocity increased then the efficiency solar chimney, collector, mathematical modeling, numerical simulation, enhance performance. roof inlet and roof outlet could be varied. the reduction in pressure at the point of reduction area is come from the reduction in area which will draw the air flow to the region of area after the reduction. this technique could be utilized to increase heat transfer between the air flow and absorber plant and between air flow and glass cover, and to increase air velocity. atit [3] scale physical models of the solar chimney were constructed. the height of the roof inlet was adjustable, so that the ratio of flow areas between roof inlet and roof outlet could be varied. in addition, there were plants with constant cross sectional area towers and a plant with a divergent tower. also there was one plant th a novel roof shape. results indicate that the aseel k. shyaa flow power increases with the decrease in the ratio of flow areas between roof inlet and roof outlet. the divergent chimney also results in significant increase in flow power compared to that of the constant area chimney. it was observed that the system with the proposed novel roof shape provides approximately the same performance as the conventional shaped system, while the ratio of flow areas between roof inlet and roof outlet for the novel system could be practically reduced. correspondingly the increase in performance to some specific value which is much lower than the typical system could be achieved. the experimental results are different from the predicted values, but show the same trends. fig. 1. solar chimney power plant [4]. 2. mathematical model the mathematical model analyzes the flow field inside solar chimney model fig (2) governing equations. the following assumptions have been considered in mathematical model 1. a steady state condition is assumed, which is an approximation because solar radiation is transient in real conditions. 2. the working air in tests proceedings as an incompressible fluid. 3. the properties of working air in all tests such as the coefficient of viscosity and the thermal conductivity are constant. 4. the working air behaves as an ideal gas. 5. both the solar collector and chimney tower are insulated to avoid heat losses to the environment. 6. air enter to the solar chimney is by natural convection. 7. the flow in the collector is considered as a flow between two parallel plates. 8. the flow is assumed one-dimensional between the collector inlet and the turbine inlet. in the chimney tower the flow is assumed one al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 59 60 flow power increases with the decrease in the ratio of flow areas between roof inlet and roof outlet. the divergent chimney also results in significant increase in flow power compared to that of the area chimney. it was observed that the system with the proposed novel roof shape provides approximately the same performance as the conventional shaped system, while the ratio of flow areas between roof inlet and roof outlet for practically reduced. correspondingly the increase in performance to some specific value which is much lower than the typical system could be achieved. the experimental results are different from the predicted values, but show the same trends. solar chimney power plant [4]. analyzes the flow fig (2), using the governing equations. the following assumptions have been considered in mathematical model: a steady state condition is assumed, which is an approximation because solar radiation is the working air in tests proceedings as an properties of working air in all tests such as the coefficient of viscosity and the thermal the working air behaves as an ideal gas. both the solar collector and chimney tower are insulated to avoid heat losses to the air enter to the solar chimney is by natural he flow in the collector is considered as a flow between two parallel plates. dimensional between the collector inlet and the turbine inlet. in the is assumed one dimensional between the turbine outlet and the tower outlet. 9. the flow through collector section has complete symmetry with the so ��� � 0 , and there is no flow in the directions ( v� , v� = 0). 10. the flow through chimney s complete symmetry with the so ��� � 0 , and there is no flow in the directions (v� , v = 0). fig. 2. solar chimney model continuity equation [5] �� �� � � �� �� � � � � �� �� � for collector: ρ ∂v ∂r � ρ v r � 0 for chimney: ρ ∂v�∂z � 0 momentum equation [5]: for collector: ρ. v ���� � �� � � μ !"# $� % � �%����% & � 0 for chimney: ρv� ∂v�∂z � gρ β �t � t*� � μ +43 ∂. ∂� 0 energy equation[5]: for collector khwarizmi engineering journal, vol. 12, no. 4, p.p. 59 71(2016) dimensional between the turbine outlet and the the flow through collector section has complete symmetry with the θ direction, , and there is no flow in the θ and z – = 0). the flow through chimney section has complete symmetry with the θ direction, , and there is no flow in the θ and r – = 0). solar chimney model. �� � � � � 0 …(1) … �2� … �3� $ �� % � � ���� – . �� % 3 � …�4� � + .v�∂z. � 1r ∂v�∂r � ∂.v�∂r. 5 … �5� aseel k. shyaa al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 59 71(2016) 61 7 +8.98:. � 1: 898: + 8.98;.5 + 2< +=8>�8: ? . + $>�: 3 . + 12 =8>�8; ? . – 13 =8>�8: + >�: ? .@ + >� 8a8: − a bc d >� 898:@ = 0 … �6� for chimney 7 +8.98:. + 1: 898: + 8.98;.5 + 2< +23 =8>�8; ? . + 12 =8>�8: ? . 5 + >� 8a8; − a bc d >� 898;@ = 0 … �7� 2.1. mathematical model in the collector the energy balance equations for the glass cover, the absorber plate and the airflow in the collector are given in the following equation respectively [6]. for the glass cover uh�t* − ti� + h ,klimtk − tin + h��to − ti� =0 … �8� for the absorber plate s + urmt* − tkn + h.mto − tkn+ h ,klimti − tkn = 0 … �9� for the airflow in the collector h��ti − to� + h.mtk − ton= qu … �10� fig. 3. heat transfer scheme of solar collector. the solar radiation absorbed by the absorber plate is s = iw αk τ … �11� where: iw : solar incidence on the surface of absorber plate w m.\ αk : absorber plate absorptivity τ : glass transmittance the mean temperature of airflow can be given by [7]: to = mto,] + to,^n2 … �12� fig. 4. thermal network for the collector of solar chimney. aseel k. shyaa al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 59 71(2016) 62 the cover glass temperature is found from equation [6]: ti = tk − uh mtk + t*nhkli + h ,kli … �13� hkli : convection heat transfer coefficient between the absorber plate and the glass cover is given by: nu = hkli × lk … �14� where: l : the spacing between the absorber plate and the glass cover, m k : thermal conductivity of air w m k\ nu : the value of nusselt number could be obtained using the expression [8]:nu = 0.54 ra� "\ for 10" ≤ ra ≤ 10j … �15� nu = 0.14 ra� #\ for 10j ≤ ra ≤ 10�� … �16� where: ra : rayleigh number and is given by: ra = gr pr = mβˋ∆tkli l#ν α … �17� g: gravitational acceleration m s.⁄ βˋ: volumetric thermal expansion coefficient of air kl� α: thermal diffusivity m. s⁄ ∆tkli : the temperature difference between the absorber plate and the glass cover h ,kli : radiation heat transfer coefficient between the absorber plate and the glass cover. it could be calculated as suggested [6]: h ,ilk = σ mti + tknmti. + tk.n = 1ϵk + 1εi − 1? … �18� the overall top heat loss coefficient from the glass cover to the ambient obtained from empirical equation as follows [6]:uh = vwx wy n ctk +mtk − t*n�n − f� 5| + 1h}~w� w� l� + σ mtk. + t*.nmtk + t*n mεk + 0.00591 n h}nl� + d2 n + f − 1 + 0.133 εkεi @ − n … �19� where: h} : the convective heat transfer coefficient due to the wind is estimated as suggested by [6]:h} = 2.8 + 3 v … �20� v : the wind speed m s⁄ n = number of glass covers f = m1 + 0.089h} − 0.1166h}εkn�1 + 0.07866 n� c = 520 �1 − 0.000051 β.� for 0° < � < 70° . for 70° < � < 90°, use β = 70° β = collector tilt (degrees) e = 0.43 �1 − 100tk � the back loss coefficient ur is given as [6]: ur = �� … �21� where k insulator thermal conductivity and δ thickness. the collector overall loss coefficient,u� is given by [6]:u� = �ur + uh� mh� h. + h� h ,kli + h. h ,klin + ur uh �h� + h.�h� h ,kli + h. uh + h. h ,kli + h� h. … �22� where: h�: convection heat transfer coefficient between the glass cover and the airflow. h.: convection heat transfer coefficient between the absorber plate and the airflow. h� and h. can be assumed to be equal and can be evaluated from the following equation: h� or h. = nu kd� … �23� where nu is given by nu = 0.0158 re�.� … �24� r = m� d� ai μ … �25� the collector efficiency factor f� is found from the equation [6]:f� = h� h ,kli + h. uh + h. h ,kli + h� h. muh + h ,kli + h�nmur + h. + h ,klin − h ,kli. … �26� collector heat removal factor is given by [6]: f� = m� c�aiu� +1 − el =�� �� ���� �� ?5 … �27� the actual useful energy gain of the hot air in the collector can be calculated by the equation below [6]:qu = ai f� �s − u�∆t  … �28� then the collector efficiency which represents the indicator to its performance can be given by: ηi = quai iw … �29� 2.2. mathematical model in the chimney the hot air which is less denser than ambient air by overcoming the gravity and friction start rising from the chimney [7], the chimney efficiency is given as [9]: aseel k. shyaa al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 59 71(2016) 63 ηi� = ph^hqu = ghi�ckt* … �30� where, hi� is the height of the chimney, thus the power contained in the flow ph^h from equation (31) can be expressed as follows [9]: ph^h = ηi�qu = ghi�ckt* qu … �31� qu is the actual useful energy gain can be obtained from equation (28). a pressure difference ∆p is produced between chimney base (collector outflow) and the surroundings [9]: ∆p = ρ* g hi� ∆tt* … �32� 3. numerical simulation the numerical simulation includes simulation of solar chimney using ansys fluent (version14.0). ansys-fluent is a computer package used for modeling fluid flow and heat transfer in complex geometries, the present study carried out fluent (version 14.0) to solve continuity, momentum, and energy, equations using a finite volume method. for the simulations, steady state analysis was chosen. the working fluid used was air which was modeled as an ideal gas. the buoyancy model was activated by specifying the gravity of -g in the (y) direction which represented real life flow. the reference pressure used was 1atm. 3.1 modeling geometry i. the geometry creation is done by the solid works (2013) software program. in the coordinate (x) and (z) are in the radial directions, and (y) is in the vertical direction. ii. in this model using the mesh sizing relevance center type fin and from mesh inserting element size equal=0.0275m[10] with set the mesh shape triangle. the mesh of reduction area is shown in fig.(5). fig. 5. mesh of reduction area for the solar chimney model. 3.2 numerical setup i. setting model in the present simulations, the basic settings of the fluent simulation are by activated the energy equation, select the realizable kϵ full buoyancy effects in the viscous model to describe the fluid flow inside the collector and the chimney, and select the discrete ordinate (do) radiation model to solve the radiation transfer equation for the following reasons, first only the do model can be used to model semi-transparent walls, and second the do model can work well across a full range of optical thicknesses. ii. setting materials properties table 1, physical properties of materials [11]. physical property air glass roof chimney wall ground insulation density kg m#⁄ 1.167 2700 7833 2719 24 thermal conductivity w mk\ 0.0242 0.78 54 202.4 0.038 specific heat j kg k\ 1006.43 840 465 871 700 refractive index [-] 1 1.526 1 1 1 emissivity [-] 0.9 0.94 thermal expansion coefficient 1 k\ 0.0033 aseel k. shyaa al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 59 71(2016) 64 iii. boundary conditions table 2, boundary conditions of the physical model.[12] 4. experimental work the simulation model with six fold collector and chimney is used in the experimental study. the diameter of collector and chimney (4.5m,20cm) respectively[13], chimney’s height is 4m, collector is inclined at 2.3°with inlet of collector is 4cm [14]. the absorption ground of collector made from black aluminum with thickness 1mm. the reduction area means that change of height of glass cover from the absorption plate at the defined distance from the center of solar chimney model .the aim from using reduction area the effect of it on air velocity. the design velocity that enters the chimney . from the simulation taken three different height of reduction area h1=3.8cm,h2=2.6cm and h3=1.28cm. making comparative with experimental work as shows in figure(6): ¥¦§¨©ª«¬ ­® :¬¯°«¨¦­ª ©:¬© ®:­± ¨ℎ¬ «¬ª¨¬: ­® «­³³¬«¨­:´©¯¦°§ ­® «­³³¬«¨­: 2.434.10 = 0.59 �3  … �33� µ2.25 = 0.59 ↔ µ = 1.33± a:-distance of reduction area from the center of collector. and height of reduction area calculated same the calculated the far of reduction area about the center. the distance a and b shown in fig.(7b) ·¸¹º»¼ ½¾ �¸¿àá¼¹½â ã�¸ã ·¸¹º»¼ á½ää¸á¼½� ¹â丼 =�.�å�.æ�0.32 �3  … �34� ç�.�" = 0.32 ↔ è = 0.0128 b:-height of reduction area (h3)in experimental work. h2 and h1 is triple and double h3 respectively.. the scale model of solar chimney power plant and reduction area shown in figure (6),(7 a,b) respectively. fig. 6. scale model of solar chimney power plant. fig. 7a. the position of reduction area. parameter value type boundary t= éê , p= 1atm pressure inlet collector inlet t= éê , p= 1atm pressure outlet chimney outlet convection + radiation wall absorbing plate convection + radiation wall glass roof fixed heat flux ë = ì wall chimney aseel k. shyaa fig. 7b. schematic diagram of shape of glass cover for the consider cases 4.1. instrumentations the following section describes the measuring instruments used on the experimental. the data are recorded every 1 hour. fig (8) shows the different instrumentations used in this work. solar meter model 776 is hand solar intensity meter was used to measure solar flux is ideal for measuring the solar energy abs by a flat panel collector. has the photovoltaic cell located on the front of the meter body so it can be placed flat on the surface and the measurement read directly from the scale. the air velocity at the chimney entrance was measured by metal van anemometer model (yk-80am). the velocity measurement range starts from (0.4) and reach to (35) m/s and temperature range (0 to 60 c°) including record function captures and displays minimum and maximum reading. the lcd shows air velocity and temperature rea simultaneously. data logger model btm has been used to record temperature data. 12 channels of thermocouples have been connected to this data acquisition system. data is saved on the sd card and can be transferred to a pc and analyzed. surface temperature of the cover (agricultural nylon) was measured using infrared thermometer model ar300.the fig. 8. photographic view of the al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 59 65 diagram of shape of glass cover for the consider cases the following section describes the measuring experimental. the data fig (8) shows the different instrumentations used in this work. the solar meter model 776 is hand solar intensity solar flux. this model is ideal for measuring the solar energy absorbed photovoltaic cell located on the front of the meter body so it can be placed flat on the surface and the measurement the air velocity at the chimney entrance was measured by metal van 80am). the velocity measurement range starts from (0.4) and reach to (35) m/s and temperature range (0 to 60 c°) including record function captures and displays minimum and maximum reading. the lcd shows air velocity and temperature reading data logger model btm-4208sd has been used to record temperature data. 12 of thermocouples have been connected data is saved on the sd card and can be transferred to a pc and temperature of the collector (agricultural nylon) was measured using infrared thermometer model ar300.the temperature measurement range (32 to 400 c°). it offers lcd backlight for visibility in the dark, a broad temperature range, and a dual display both current and maximum measurements. points are located on the along it with 39 cm distance between each one. the first point begins at 4 cm from inlet of collector. this distribution is constant in all cases. ten thermocouples k-type the ambient temperature, temperature inside the solar chimney. the thermocouples and its locations are defined as follows. • five thermocouples are located on the absorber plate divided along i distance between each one. thermocouple begins at 4 cm from inlet of collector. this distribution is constant in all cases. • five thermocouples are located in the flow direction of air to measure air temperature. these thermocouples are divided along direction with 52 cm distance between each one. all data are automatically collected and recorded in a pc through data logger. the positions of the thermocouples are as shown in fig. (9). . photographic view of the instrumentation. khwarizmi engineering journal, vol. 12, no. 4, p.p. 59 71(2016) diagram of shape of glass cover for the consider cases. temperature measurement range (32 to 400 c°). it offers lcd backlight for visibility in the dark, a broad temperature range, and a dual display for both current and maximum measurements. five points are located on the collector cover divided along it with 39 cm distance between each one. the first point begins at 4 cm from inlet of collector. this distribution is constant in all cases. type were used to measure the ambient temperature, absorber plate and air temperature inside the solar chimney. the thermocouples and its locations are defined as thermocouples are located on the divided along it with 39 cm distance between each one. the first thermocouple begins at 4 cm from inlet of collector. this distribution is constant in all cases. thermocouples are located in the flow direction of air to measure air temperature. re divided along air flow with 52 cm distance between each one. all data are automatically collected and recorded in a pc through data logger. the positions of the thermocouples are as shown in aseel k. shyaa al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 59 71(2016) 66 fig. 9. layout of thermocouples and data collecting points. 5. results and discussions case studies of experimental works were taken in may month at baghdad city under actual weather conditions of this month. the experimental data had collected from 9 am to 2 pm. fig. (10a) presents the behavior of the airflow velocity experimentally at the inlet chimney tower with time at various collector reduction areas . the highest velocity occurs at 1:00pm, when the levels of incident solar radiation and the airflow temperatures are higher. higher values are found at the lower collector reduction area. for the prototype with the collector reduction area 3.8 cm, the maximum achievable velocity is 2.55 m/s at 1:00pm. by decreasing the collector reduction area to 1.28 cm, the maximum achieved velocity rises to 3.15 m/s which is about an 19.04% enhancement. a lower collector reduction area means a smaller collector flow area, giving a higher airflow velocity. fig. (10b) shows the variation of air velocity with time among inclination angle and reduction area of collector. it is noticed that air velocity corresponding to reduction area h=1.28 cm is higher than that to inclination angle 2.3 ° resulting from the reduction of flow area. by decreasing the collector reduction area, the maximum achieved velocity rises from 2.39 m/s to 3.15 m/s which is about an 24.12% enhancement, the airflow temperature inside the solar collector increased with respect to the solar radiation intensity(i). it is also observed that the airflow temperature at h3= 1.28 cm of the solar collector is higher than those at h1= 3.8 cm, and h2= 2.6 cm during the whole testing period. fig. (14) illustrates the history of airflow temperature, for three different values of the collector reduction areas. higher collector reduction area reduces the airflow temperature due to the increase of the mass flow rate. mass flow rate increased by increasing flow area in the collector. the maximum absorber ground temperature recorded at 1:00pm was 65 °c, where the collector cover temperature reached the value of 43°c and the air temperature was 40 °c these results for inclination angle of collector (2.3°) fig.(14a). while for collector reduction area (h3= 1.28 cm), the maximum absorber ground temperature was 93 °c, the collector cover temperature was 67°c and the air temperature was 62°c. the comparison showed that the reduction area was more effective than that inclination angle fig (14b). fig.(11a) demonstrates the evolution of output power versus time for three different values of the collector reduction area. this figure illustrates that the output power increases while the collector reduction area is decreased. current result predict higher output power with collector reduction area of h = 1.28 cm than a plants with a collector reduction area of h = 3.8 cm and h=2.6 cm. the output power for reduction area of (1.28cm) is observed higher than that for inclination angle of collector of 2.3° shown in fig.(11b) , because it is the effect of lower reduction area in collector. it can be observe the collector efficiency ( íͦáï ðñòá ó � increases as the reduction area of the collector decreases due to its higher outlet temperature and airflow velocity. fig. (12a) demonstrates that the collector efficiency increases from 29% to 51 % according to the decrease in collector areas from h1= 3.8 cm to h3= 1.28 cm. aseel k. shyaa al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 59 71(2016) 67 fig. 10. variation of air velocity versus time (a)with reduction area. (b) with and without reduction area. fig. 11. variation output power versus time (a)with reduction area.(b)with and without reduction area. fig. 12. variation efficiency versus time(a) with reduction area. (b) with and without reduction area. aseel k. shyaa al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 59 71(2016) 68 fig. 13.contours and vectors of air design velocity (m/s) (a)without reduction area.(b)at h1=3.8cm.( c)at h2=2.6cm. (d) at h3=1.28cm. fig. 14. contours of static air temperature(c°) (a)without reduction area.(b)at h1=3.8cm.( c)at h2=2.6cm. (d) at h3=1.28cm. aseel k. shyaa al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 59 71(2016) 69 fig. 15. contours of static pressure(pa) (a)without reduction area.(b)at h1=3.8cm.( c) at h2=2.6cm. (d) at h3=1.28cm. 6. conclusions according to the discussion of the obtained results, many conclusions can be extracted such as: 1. the effects of three different collector reduction areas on solar chimney are presented. it can be concluded that decreasing the collector reduction area significantly influences on the performance of solar chimney. in the present study, collector reduction area of 1.28 cm provides the best performance. 2. the collector inclination angle is also important parameter in the solar chimney. the inclination angle of collector should be at optimum angle to provide best performance for solar chimney. 3. the reduction area is found to perform better than an inclination angle in terms of airflow velocity and temperature. 4. the thermal efficiency of the solar collector is dependent upon the magnitude of temperature 5. rise (∆t) and the airflow velocity, and also of the solar radiation. error analysis when experimental tests are carried out, an accurate reading should be taken, since any mistakes could reduce the accuracy of the results. there is more than one method which can be used to find the experimental error. one of these methods is that given by: kline & melintock [11] which depends on the assumption that when calculating a variable as r for example, which is to be calculated from a certain experimental test. this variable is assumed to be related to a number of independent variables as (v1, v2… vn) )v v,r(v=r n21 ……… …(35) for small variations in the variables, this relation can be expressed in linear form as: n n 2 2 1 1 δv v r δv v r δv v r δr ∂ ∂++∂ ∂+∂ ∂= ........ …(36) hence, the uncertainty intervals (w) in the result can be given as 2 1                                         ∂ ∂++ ∂ ∂+ ∂ ∂= 222 rw n n 2 2 1 1 w v rw v rw v r ............ …(37) aseel k. shyaa al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 59 71(2016) 70 eq. (38) is greatly simplified upon dividing by eq. (36) to non-dimensionalize                                       ∂ ∂++ ∂ ∂+ ∂ ∂= r w nv r r w v r r w v r r w n 2 2 2 2 1 1 2 r ............ …(38) hence, the experimental errors that may happen in the used variables are given in table (3) for the measuring devices; table 3, uncertainties of measuring tools. independent variables (v) uncertainty interval (w) temperature 0.2 ºc velocity 0.02 solar intensity 0.02 error in calculating the value of collector efficiency ôá = bõ añ öñ µ ∆9 × 3 √32 ´á. … �39� collector efficiency is a functional of several variables, each subject to an uncertainty. ôá = ®�öñ , ∆9, ×� … �40� 8ôá8∆9 = bõ añ öñ µ × 3 √32 ´á. … �41� 8ôá8öñ = bõ añ µ ∆9 × 3 √32 ´á. … �42� 8ôá8× = bõ añ µ öñ ∆9 ×. 3√32 ´á. … �43� therefore the uncertainty intervals (w) in the result can be given as follows; ùúû = += 8ôá8∆9 ù∆9?. + =8ôá8öñ ùöñ?. + =8ôá8× ù×?.5 �. … �44� üýûúû = �.�æ".�å� = 0.00226 % 7. references [1] schlaich bergermann und partner, “solar updraft tower”, october 2011 http:\\www.solar-updraft-tower.com. [2] mark e.steinke,satish g.kandlikar, “singlephase heat transfer enhancement techniques in microchannel and minichannel flows”, azme,2004. [3] atit koonsrisuk, “analysis of flow in solar chimney for an optimal design purpose”, thesis, 2009. [4] hermann f. fasel, fanlong meng, ehsan shams, andreas gross, “cfd analysis for solar chimney power plants”, solar energy 98 (2013) pp. (12–22). [5] qahtan a. al-nakeeb, “computational analysis of geometry alteration on the performance of a solar system to generate air flow”,thesis, iraq, 2001. [6] duffie, john a. and beckmann, william a. (1980), “solar engineering of thermal processes”, book, john wiley & sons, new york. [7] m.a. dos s. bernardes, a. voß, g. weinrebe, “thermal and technical analyses of solar chimneys”, solar energy 75 (2003) pp. (511–524). [8] mehrdad ghalamchi, alibakhsh kasaeian, “an experimental study on the thermal performance of solar chimney with different dimensional parameters” ,volume 91, 2016, pp. (477–483). [9] roozbeh sangi, “performance evaluation of solar chimney power plants in iran”, renewable and sustainable energy reviews 16 ,(2012), pp. (704– 710). [10] abbas jassem jubear abbas, “numerical and experimental study of turbine solar chimney performance”,thesis, iraq, (2014). [11] j.p. holman, heat transfer 5th edition, book ,mcgraw-hill, 1981. [12] ansys fluent 12.0 user’s guide and theory guide. [13] bashir ahmed danzomo, sani jibrin, “similitude model design and performance evaluations of solar tower system”, arpn journal of engineering and applied sciences, vol. 7, no. 4, 2012. [14] haider salim nuri, “enhancement of solar chimney performance by using geometrical and thermal energy storage techniques”, thesis, 2014. ��� 4، ا���د�12��� ا���ارز�� ا���� �� ا� ��� ا �� ���� ���ع� ،71-59 )2016( 71 ��� $ #�" إداء ا� ���� ا��� درا � # ��� و#�د*� �()'�& �%� ا� ***�&*4 �3*� #�1د ** ا���1اوي #�1س /�. را-$ * �� ���� ���عأ *،**،***������������ ا� !��&%��/ $#" ا& �'� ا�*�()� ا aseelkhshyaa@yahoo.com �+,-�:ا0��',و�. ا * rafa_a70@yahoo.com �+,-�: ا0��',و�. ا ** memomoaed@yahoo.com رو�� ا��ر�د :ا��� *** �� ا��5 ��� 34&رت &'�� ا��!,��6�7(�35ت ا&8 �7 � 9 ) 8�#�:���3d$� ا� �b�c ا(&�� �(�35 ا��3$� ا�:�#�� 4).م ١٩٣٠ط� ا���; 8 ا . ���5��� ھ. ا��را�ا fg �+د�gو ��d�g .#�:��qm ا��*�i ا�:�#. و�5�bp f�7 ا�o')0ص .( �m3 ا�bl�0ض j. ا��*�i ا f�7 ع�b4ا0ر ,�s4 . )4 ض�bl�0ا �m3 ع ((�$ .#�:���d�g ار�g�b4ت ( �m3 ا�bl�0ض �s4, سٓ رِ دُ .ا�'. �4&ن ذات (7� yz,) fg f�() ا��*�i وھ9ا ا�-)� +)'�� w xdg*" ا� &ذج ا��#')�t) ا��*�i ا �" xdg ا�'&ا�. )١.٢٨، ٢.٦، ٣.٨ (b�w 4" ا�'l�م `a`� ار�g�b4ت وg�د+�. xdg ض�bl�0ا �m3 ) ت�g�b4ار ,�`g4 8�ا�!�ف (f ھ9ا ا�-b5 ھ& درا �����o'��" ھ&١.٢٨ان ا�'l�ام ا0ر�b4ع n �7 ا� '� g.( m6� )�t; ا���; � ةا�#,ع ا�9ي m4&م j+,5'7 ر+i ا�'&رf�7 ا��&%&د(ا�#,8g اtoj0ا p-#�وا �,�g ا�*,+�ن .j ز+�ده x�s4دي ا�x ز+�ده j. ذاك g� t�dm4 ا0ر�b4ع f�7 ا�#qm وا��mع 8w�#) f) t�dm4 . (4 ا�*,+�ن دا;t ا��*�i ا�:�#. (�� +sدي ا ��#�:� .�bzءة ا���; � ا تقدير أداء شغل المبدل الحراري بواسطة اسلوب التبريد التبخيري al-khwarizmi engineering journal al-khwarizmi engineering journal, vol.5, no.4, pp 115-124 (2009) حقذَر أداء شغم انمبذل انحرارٌ بىاسطت اسهىة انخبرَذ انخبخُرٌ ػمبد صذَق محمذ صالح كرَم جىاد ر ثٌؾجِؼز ثٌضىٌٕٛٛؽٟ/لغُ ٕ٘ذعز ثالٔضجػ ٚثٌّؼجدْ (received 3 march 2008; accepted 29 october 2008) : انخالصت . ٌضذش٠ذٖ ٚفك ِذذأ ثٌضذش٠ذ ثٌضذخ١شٞ ػٍٝ ِشفٍض١ٓ (٘ٛثء ٔمٟ )صُ فٟ ٘زث ثٌذقظ صظ١ُّ ٚإٔشجء ِذشدر ٘ٛثء صذخ١ش٠ز صغضخذَ ٘ٛثء خجسؽٟ دجٌىجًِ cm40 × 30 )أٔشأس ثٌّٕظِٛز ثٌّخضذش٠ز ٚرٌه ِٓ خالي صظ١ُّ ٚصظ١ٕغ ِذجدي فشثسٞ طفجةقٟ ِضؼجِذ ثٌؾش٠جْ ِٓ طفجةـ عذ١ىز ثأل١ٌَّٕٛ ٚدجألدؼجد ٚرٌه ٌض٠جدر ٔغذز صذًٍ ٘زٖ ثٌغطٛؿ , ِٓ ؽجٔخ ثٌمٕٛثس ثٌّشؽذز دجٌّجء ( sawdust )صُ ِؼجٍِز عطٛؿ ثٌّذجدي ثٌقشثسٞ دّجدر ٔشجسر ثٌخشخ . ( 50× . دجٌّجء ٚدجٌضجٌٟ صقغ١ٓ وفجءر ٚأدثء ِذشدر ثٌٙٛثء ف١ظ دسط صغ١ش دؼغ ثٌؼٛثًِ ثٌّؤعشر فٟ ثألدثء ثٌقشثسٞ ٌّذشدر ,صُ أؽشثء دسثعز ػ١ٍّز ػٍٝ ِٕظِٛز ثٌضذش٠ذ ثٌّزوٛسر ٌٍضّىٓ ِٓ صم١١ُ أدثء٘ج . ثٌٙٛثء ثٌضذخ١ش٠ز وّؼذي صذفك ثٌٙٛثء ثٌّشثد صذش٠ذٖ ٚصجع١ش ثٌٙذٛؽ فٟ ثٌؼغؾ ثالعضجصٟ ٌٍٙٛثء فؼال ػٓ دسثعز صجط١ش ِؼجًِ ثٔضمجي ثٌقشثسر َُّ . ( l / hr 1050 ) إٌٝ ( l / hr 144 )صغ١١ش و١ّز ثٌّجء ِٓ ٚ , ( m3 / hr 1461.50 ) إٌٝ ( m3 / hr 142.90 )س ِؼذي صذفك ثٌٙٛثء ِٓ ٞصغٟص وّج صذ١ٓ ِٓ ثٌذسثعز أْ ِؼجٍِز عطٛؿ ,( m3 / hr 824.7 )ٌمذ أظٙشس ثٌٕضجةؼ ثٌؼ١ٍّز أْ أفؼً و١ّز ٌٍٙٛثء ٠ّىٓ صؾ١ٙض٘ج ِٓ لذً ِذشدر ثٌٙٛثء ٟ٘ 21 ) ٌىٕٙج صض٠ذ ِٓ ِمذثس ثٌٙذٛؽ فٟ ثٌؼغؾ ثالعضجصٟ ٌٍٙٛثء دٕغذز ,( % 10 )ثٌّذجدي ثٌقشثسٞ دٕشجسر ثٌخشخ صقغٓ ِٓ وفجءر ٚأدثء ِذشدر ثٌٙٛثء دمشثدز ٚأظٙشس ثٌٕضجةؼ أ٠ؼجًا ػذَ إِىج١ٔز ثعضخذثَ ِذشدر ثٌٙٛثء فٟ ثٌّٕجؽك ثٌضٟ ٠ض٠ذ . ( % 9 ) فضٕضؼ ػٓ رٌه ص٠جدر فٟ ثٌطجلز ثٌّغضٍٙىز دّج ٠مجسح , صمش٠ذجًا ( % .( g moisture / kg dry air 11.9 )ف١ٙج ثٌّقضٜٛ ثٌشؽٛدٟ ٌٍٙٛثء ػٓ . ثٌّذجدي ثٌقشثسٞ, ثٌضذش٠ذ ثٌضذخ١شٞ, ِذشدر ثٌٙٛثء: انكهمبث انمفخبحُت نمقذمت ث .1 ٠ضؼّٓ صى١١ف ثٌٙٛثء ػ١ٍّض١ٓ سة١غ١ض١ٓ , ثٌضذفتز فٟ فظً ثٌشضجء ف١ظ دسؽز فشثسر ثٌٙٛثء ٚثؽتز ٔغذ١ج ًا ف١ظجس ثٌٝ ص٠جدصٗ .ٚوزٌه ثٌضذش٠ذ فٟ فظً ثٌظ١ف, دٕغخ صضٛثفك ِغ سثفز ثالٔغجْ ٌٚغشع صذش٠ذ ثٌٙٛثء ٌٍقظٛي ػٍٝ ظشٚف ثٌّٕجعذز ٌٍشثفز ثالٌٚٝ ٟ٘ ؽش٠مز ثٌضذش٠ذ , فٕٙجن ؽش٠مضجْ سة١غ١ضجْ ٌٍضذش٠ذ دجٔؼغجؽ ثٌذخجس ٚثٌضٟ صؼضّذ فٟ ػٍّٙج دشىً أعجعٟ ػٍٝ دٚسر ثٌّضىٛٔز ِٓ ثؽضثةٙج ثٌّؼشٚفز (ثالٔؼغجؽ١ز )ثٌضغ١ٍؼ ث١ٌّىج١ٔى١ز ج ثٌطش٠ك ثٌغج١ٔز . ٟٚ٘ ثٌؼجغؾ ٚثٌّىغف ٚ ثٌز ثٌضّذد ٚثٌّذخش ِّ ث فٟٙ ؽش٠مز ثٌضذش٠ذ دضذخ١ش ثٌّجء دثخً ص١جس ثٌٙٛثء ثٌّشثد صذش٠ذٖ ّْ وً ِٓ ؽشق ثٌضذش٠ذ ث٢ٔفز ثٌزوش . ٚصغّٝ دجٌضذش٠ذ ثٌضذخ١شٞ إ ٌٙج ؽش٠مز ػًّ صخضٍف ػٓ ثألخشٜ دجخضالف ثإلؽشثءثس ثٌف١ض٠ج٠ٚز خالي ػ١ٍّز ثٌضذش٠ذ ٚدٕجءث ًا ػٍٝ رٌه فئْ ٌىً ؽش٠مز وفجءر ِؼ١ٕز ٠ؼضّذ ثعٍٛح ثٌضذش٠ذ ثٌضذخ١شٞ ػٍٝ صق٠ًٛ ثٌقشثر ثٌّقغٛعز ٌٍٙٛثء ثٌٝ ؽجلز وجِٕز صؼًّ ػٍٝ صذخ١ش ثٌّجء ثٌزٞ فجرث , دذٚسٖ ٠ؤدٞ ثٌٝ صخف١غ دسؽز فشثسر ثٌّجء ثٌٝ فذٚد ِؼ١ٕز وجٔش ػ١ٍّز صذجدي ثٌقشثسر صؼًّ دجٌضّجط ثٌّذجشش د١ٓ ثٌٙٛثء ٚصضظف ٘زٖ دجٔٙج , ٚثٌّجء ع١ّش صٍه دجٌضذش٠ذ ثٌضذخ١شٞ ثٌّذجشش رثس وٍفز صشغ١ٍ١ز ث١ٌٚز ٚثؽتز ِغ ثعضٙالن ل١ًٍ ٌٍطجلز ثٌىٙشدجة١ز ٔغذز ًا ٌالؽٙضر ثالٔؼغجؽ١ز ٌىٕٙج الصغضٛفٟ فجٌز ثٌؾٛ ثٌّالةُ ٌزٌه صضث٠ذ ثال٘ضّجَ دّذذأ ثٌضذش٠ذ ثٌضذخ١شٞ , ٌٍشثفز دثخً ثٌق١ض ٚصضث٠ذس ِقجٚالس ثالعضفجدر ِٓ ٘زث ثالعٍٛح دٙذف صط٠ٛشٖ ٌٍقظٛي ػٍٝ ٘ٛثء دجسد دّقضٜٛ سؽٛدٟ ثلً ٚرٌه ِٓ خالي ِٕظِٛجس ثٌضذش٠ذ ثٌضذخ١شٞ ثٌغ١ش ِذجشش ٚثٌضٟ صغضف١ذ ِٓ ِذذث ثٌضذش٠ذ ثٌضذخ١شٞ ثٌّذجشش ٌضذش٠ذ ثٌٙٛثء دجعضؼّجي ِذشدثس ثٌٙٛثء ثٌضذخ١ش٠ز ثٚ دضذش٠ذ ثٌّجء وجٌقجي دجدشثػ ثٌضذش٠ذ عُ ٠غضخذَ ٘زث ثٌٙٛثء ثٚ ثٌّجء ثٌّذشد ٌضذش٠ذ ثٌٙٛثء ثٌّؾٙض ثٌٝ ثٌق١ض ػٓ ؽشق ثِشثسٖ دجفذٜ ؽٙضٟ ِذجدي فشثسٞ ٠ّٚشس ثٌٙٛثء ثٌّشثد صذش٠ذٖ ِٓ دجٌؾٙز ثالخشٜ ٚدزٌه ٠قظً ثٌضذش٠ذ ِٓ غ١ش صالِظ د١ٓ ٚ٘زٖ ثٌؼ١ٍّز صغّٝ دجٌضذش٠ذ ثٌّقغٛط ثٞ ثْ ثٌٙٛثء , ثٌّجةؼ١ٓ . ع١ذشد دذْٚ ثػجفز سؽٛدز ث١ٌٗ صض١ّض ِٕظِٛز ثٌضذش٠ذ ثٌضذخ١شٞ غ١ش ثٌّذجشش دأٔٙج رثس وفجءر ػج١ٌز ِمجسٔز دضٍه ثٌضٟ صؼًّ دجٌضذش٠ذ ثٌضذخ١شٞ ثٌّذجشش فمؾ ٚوزٌه صىْٛ ل١ٍٍز ثٌىٍفز ِٓ ف١ظ ثٌضذش٠ذ ٚثٌظ١جٔز ثالّ ثٔٙج صغضٍٙه ؽجلز وٙشدجة١ز ثػٍٝ ِّج فٟ ثالٌٚٝ ٚٔغذز ًا الؽٙضر ثٌضذش٠ذ ث١ٌّىج١ٔى١ز فجْ ّ ثؽٙضر ثٌضذش٠ذ ثٌضذخ١شٞ غ١ش ثٌّذجشش رثس . ثعضٙالن ٌٍطجلز ثلً دىغ١ش صٕمغُ ؽشق ثٌضذش٠ذ دجٌضذخ١ش وّج ٟ٘ ِزوٛسر فٟ ثغٍخ : ِظجدس ثٌضى١١ف ثٌٝ عالعز ثلغجَ ثٌضذش٠ذ ثٌضذخ١شٞ ثٌّذجشش : 1 ثٌضذش٠ذ ثٌضذخ١شٞ غ١ش ثٌّذجشش : 2 ثٌضذش٠ذ ثٌضذخ١شٞ ػٍٝ ِشفٍض١ٓ : 3 124 -115، صفحت 4د ، انؼذ 5 مجهت انخىارزمٍ انهنذسُت انمجهذ ػمبد صذَق محمذ (200 9) 116 انخبرَذ انخبخُرٌ انمببشر 1.1 صقذط ػ١ٍّز صذش٠ذ ثٌٙٛثء ػٕذِج ٠ضالِظ ٚرٌه ِٓ خالي ٚصىْٛ ثٌؼ١ٍّز دغذٛس . ِشٚسٖ ِٓ ٚعؾ صذخ١شٞ دغشػز ِؼ١ٕز ثٌّقضٜٛ ثٌقشثسٞ ٌٍٙٛثء ٚثٌضٟ ٠ٕجظش٘ج ِٓ ثٌؾٙز ثٌضق١ٍ١ٍز ػٍٝ دجفضشثع ػذَ فظٛي ثٔضمجي فشثسر د١ٓ ؽٙجص , ثٔٙج ػ١ٍّز ثد٠ذجص١ز ٠ؾخ ثْ صىْٛ دسؽز [1].ثٌضذش٠ذ ٚثٌّق١ؾ ثٌخجسؽٟ ثعٕجء ثٌضذش٠ذ إالّ فٍٓ ٚفشثسر ثٌّجء ثلً ِٓ دسؽز فشسر ثٌذظٍز ثٌؾجف ٌٍٙٛثء . ٠قظً ثٌضذخش ٌٍّجء ٚدجٌضجٌٟ ال٠ىْٛ ٕ٘جن صذش٠ذ ٌٍٙٛثء انخبرَذ انخبخُرٌ غُر انمببشر1.2 صقذط ػ١ٍّز ثٌضذش٠ذ ٚفك ٘زث ثٌّذذأ ِٓ غ١ش ثْ ٠قظً صّجط د١ٓ ٚغجٌذج ًا ِجصىْٛ ػٓ ؽش٠ك , ثٌٙٛثء ثٌّشثد صذش٠ذٖ ٚٚعؾ ثٌضذش٠ذ ِذجدي فشثسٞ ف١ظ ٠ّشس ثٌٙٛثء ثٌغجخٓ ِٓ ثفذٜ ؽٙجس ثٌّذجدي ٠ٚؾٙض ٘ٛثء دجسد سؽخ ثٚ ِجء دجسد ِٓ ثٌؾٙز ثالخشٜ ف١قظً صذجدي فشثسٞ د١ٓ ثٌّجةؼ١ٓ ِٓ دْٚ ثِضضثػ فشثسٞ د١ّٕٙج ف١ذشد ِقضٛثٖ ثٌشؽٛدٟ ٠ٚطٍك ػ١ٍٙج ػ١ٍّز ثٌضذش٠ذ دغذٛسثٌٙٛثء ثٌغجخٓ . ثٌّقغٛط انخبرَذ انخبخُرٌ ػهً مرحهخُن 1.3 ٘زٖ ثٌطش٠مز ِٓ ثٌضذش٠ذ ٟ٘ ٔضجػ دِؼ ثٌطش٠مض١ٓ ثٌغجدمض١ٓ ف١ظ ٠ضُ صذش٠ذ ثٌٙٛثء فٟ ثٌّشفٍز ثالٌٚٝ صذش٠ذث ًا ِقغٛعج ًا , ثٌزوش ػٓ ؽش٠ك ِذجدي فشثسٞ ِٕجعخ ِٚٓ عُ ٠ؼشع ثٌٙٛثء ثٌٝ ِٓ ثٌّّىٓ . ػ١ٍّز صذش٠ذ دجٌضذخ١ش ثٌّذجشش فٟ ثٌّشفٍز ثٌغج١ٔز ثعضخذثَ ٘زٖ ثٌطش٠مز فٟ ثٌّٕجؽك رثس ثٌظشٚف ثٌّٕجخ١ز ثٌضٟ صض٠ذ ف١ٙج دسؽز فشثسر ثٌذظٍز ثٌشؽذز عالط دسؽجس ػّج ٟ٘ ػ١ٍٗ فٟ ثٌّٕجؽك ثٌضٟ ٠شجع ف١ٙج ثعضخذثَ ثٌضذش٠ذ ثٌضذخ١شٞ ثٌّذجشش ثٞ فٟ ثٌّٕجؽك ػج١ٌز ثٌشؽٛدز ٚ٘زث ِٓ ث٠ؾجد١جس ٘زٖ [. 2 ]ثٌطش٠مز فٟ ثٌّٕجؽك ثٌضٟ ٠ىْٛ ف١ٙج ِؼذي دسؽز فشثسر ثٌذظٍز c)ثٌشؽذز ٌٍٙٛثء  ثٚ ثلً دم١ًٍ فجْ ِؼذي ثٌطجلز ثٌّغضٍٙىز ( 19 ( ton / kw 0.22 )ٌٍطٓ ثٌٛثفذ ِٓ ثٌضذش٠ذ ٘ٛ ِج٠مجسح فٟ ثٌّٕجؽك ثٌضٟ ِؼذي دسؽز ( ton / kw 0.81 )ِٚج٠مجسح c )فشثسصٙج ٌٍذظٍز ثٌشؽذز  ِٚمجسٔز ِغ , ثٚ ثوغش دم١ًٍ ( 23 ثٌّى١فجس )ثؽٙضر ثٌضذش٠ذ ثالٔؼغجؽ١ز رثس ثٌّىغف ثٌّذشد دجٌٙٛثء فئْ ِؼذي ثٌطجلز ثٌّغضٍٙىز ع٠ٕٛج ًا ٌٍطٓ ثٌٛثفذ ِٓ (ثالػض١جد٠ز ٌمذ ؽشس ِقجٚالس ػذ٠ذر . [3( ]ton / kw 1.46)ثٌضذش٠ذ ٠ذٍغ فٟ ثٌغٕٛثس ثٌّجػ١ز ٌذسثعز ثدثء ِذشدثس ثٌٙٛثء ثٌضٟ صؼًّ دجعٍٛح ثٌضذش٠ذ ثٌضذخ١شٞ ثٌّذجشش دغ١ز صط٠ٛش٘ج دضقغ١ٓ ثدثةٙج ٚف١ّج . ٌضٍذ١ز أفؼً ِغضٜٛ ٌشثفز ثالٔغجْ دثخً ثٌق١ض ثٌّى١ف ٠ٍٟ ِشثؽؼز ٌذؼغ ثٌذقٛط ثالؽٕذ١ز ٚثٌّق١ٍز وّشثؽؼز صف١ذ . ثٌذجفظ دسثعز ػٓ [4( ].chan and c.y.l)ثؽشٜ ثٌذجفغجْ ثالدثء ثٌقشثسٞ الؽٙضر ثٌضذش٠ذ ثٌضذخ١شٞ ثٌّذجشش ِٚمجسٔضٙج ِغ ٚثعضٕضؾج ثْ ِذشدثس ثٌٙٛثء ثٌضذخ١ش٠ز , ثؽٙضر ثٌضذش٠ذ ث١ٌّىج١ٔى١ز ثوغش ثلضظجد٠ز ِٓ صٍه ثٌضٟ صؼًّ دجٌذٚسثس ثالٔؼغجؽ١ز دغش دذسثعز صطذ١م١ز ػٍٝ ِذشدثس [ 5] (ِشصؼٝ )لجَ . ِشثس صمش٠ذج , دغ١ز صقغ١ٓ وفجةضٙج ( cfm 3500 )٘ٛثء صؾجس٠ز رثس عؼـز ف١ظ ثعضخذَ فشٛر فذ١ذجس ثٌذٌٛغضش٠ٓ ثٌظغ١شر وٛعؾ ٌٍضذـــخش ( . cm 7)ٚعّه (kg 0.5)دذال ًا ػٓ ثٌقشٛر ثٌخشذ١ز ٚدىضٍز ثعضٕضؼ ثٌذجفظ ثٔٗ دجالِىجْ ثعضخذثَ ٘زٖ ثٌقشٛر ٌفضشر ؽ٠ٍٛز دْٚ ثٌٍؾٛء ثٌٝ صذذ٠ٍٙج د١ٓ فضــــشر ٚثخشٜ ٚٚؽذ ثٔٙج ِٕجعذز ثلضظجد٠جًا إال ثْ صٕظ١ُ ٘زٖ ثٌقشٛر فٟ ثالو١جط ثٌّشذىز دظٛسر ِضٕجعمز . ٠ؼضذش طؼذج ًا ػ١ٍّجس ثٔضمجي ثٌقشثسر [ 6 ] ( khatib -al )دسط ٚثٌىضٍز فٟ ِٕظِٛز ثٌضذش٠ذ ثٌضذخ١شٞ دجعضخذثَ ؽٙجص ثٌضذش٠ذ ثؽش٠ش ثٌضؾجسح ثٌؼ١ٍّز ٚلٛسٔش ٔضجةؾٙج ِغ ٔضجةؼ . ثٌّغذك ٌٍّجء ثٌّغ١ً ثٌقغجدٟ ٚثٌؼذدٞ ٌضقذ٠ذ ثٌم١ُ ثٌؼذد٠ز ٌّؼجًِ ثٔضمجي ثٌقشثسر ِٚؼجًِ ثٔضمجي ثٌىضٍز ٚد١جْ ِذٜ ثِىج١ٔز ثعضخذثَ ؽٙجص ٚلذ ثظٙشس ثٌٕضجةؼ ثْ صأع١ش ثعضؼّجي ؽٙجص , ثٌضذش٠ذ ثٌّغذك ٌٍّجء ثٌضذش٠ذ ثٌّغذك ٌٍّجء ػٍٝ وفجءر ثٌّٕظِٛز ل١ًٍ ٠ٚقضجػ ٌٍغ١طشر . ػٍٝ ػذر ػٛثًِ ٌالعضفجدر ِٓ و١ّز ثٌقشثسر ثٌّقغٛعز ٌمذ وجْ ِٓ ثٌّضٛلغ ثْ ٠ىْٛ صأع١ش ثٌضذش٠ذ ثٌّغذك ٌٍّجء ل١ٍال ًا ٌٚىٓ , ثػجفز ثٌٝ ثْ ثعضٙالن ثٌطجلز ثٌىٙشدجة١ز ع١ىْٛ ثػٍٝ ثٌفجةذر ثٌؼ١ٍّز ٌٙزث ثٌذقظ صىّٓ فٟ ثخض١جسٖ ٌغالط ّٔجرػ س٠جػ١ز ٌّقجٌٚز صفغ١ش ػ١ٍّز ثٔضمجي ثٌقشثسر ٚثٌىضٍٟ ثٌقجطٍز ثعٕجء ػ١ٍّز : ثٌضذخ١ش فٟ ثٌقشٛر ٚ٘زٖ ثٌّٕجرػ ٟ٘ ثالٚي ٠ضُ ف١ٗ صّغ١ً ثٌّغجفجس ثٌضٟ ٠ٕفز خالٌٙج ثٌٙٛثء فٟ ثٌقشٛر دّؾّٛػز ِٓ ثالٔجد١خ دؼذد ِؼ١ٓ ٚلطش ِؼ١ٓ ٚثصؾجٖ ثٌّٕٛرػ ثٌغجٟٔ ٠ضّغً فٟ ثْ .ِقٛس٘ج دجصؾجٖ خؾ ؽش٠جْ ثٌٙٛثء ِجدر ثٌقشٛر ِضأٌفز ِٓ ػذد ِٓ ثٌمؼذجْ صذؼذ ػٓ دؼؼٙج دّغجفجس ِٕضظّز ٚثٌٙٛثء ٠ّش ِٓ خالي ثٌفشثغجس ثٌضٟ صفظً ثٌمؼذجْ ػٓ ثِج ثٌغجٌظ فضىْٛ ف١ٗ ثٌّجدر ثٌظٍذز ٌٍقشٛر ِضىٛٔز ِٓ . دؼؼٙج . ؽغ١ّجس وش٠ٚز دقؾُ ِٕضظُ ِٚٛصػز دجٔضؼجَ فٟ ثٌقشٛر ِالس ثٔضمجي ثٌمذ ثعضٕضؼ ِٓ ٘زٖ ثٌّٕجرػ ثٌغالعز ل١ّج ًا ٌّغ د١ٕٙج ٚد١ٓ ثٌم١ُ ثٌّغضخشؽز ػ١ٍّج ًا ْثٌقشثسر ٚثٌىضٍز ٚػٕذِج ٠مجس ٚؽذ ثْ ثٌّٕٛرػ ثٌغجٟٔ ٘ٛ ثاللشح ٌضّغ١ً ػ١ٍّجس ثالٔضمجي دسثعز ػٍٝ [7] ( pescod )ٌمذ ثؽشٜ ثٌذجفظ.ثٌقشثسٞ ثٌّذجدالس ثٌقشثس٠ز ثٌظفجةق١ز دٙذف صط٠ٛش٘ج ِٓ خالي ثعضخذثَ ثٌٍذثةٓ فٟ صظ١ٕغ ثٌّذجدي دؼذ ثْ وجٔش ثٌّذجدالس ثٌظفجةق١ز صظٕغ ِٓ ثٌّؼجدْ ف١ظ وٍفز ثٌظ١جٔز ثٌذج٘ؼز ٚثالٔشجء ثٌّىٍف ػًّ ثٌذجفظ . ِّج شؾغ ثٌذجفظ فٟ ثٌٕظش ثٌٝ ثٌٕجف١ز ثاللضظجد٠ز ػٍٝ صط٠ٛش ّٔٛرػ صؾجسٞ ٌّذجدي فشثسٞ طفجةقٟ رٞ عطٛؿ ِذٍٍز دجٌّجء دغ١ز ثعضخذثِٗ ِٕظِٛجس ثٌضذش٠ذ ثٌضذخ١شٞ غ١ش ( mm 0.25 )ف١ظ ثعضؼًّ طفجةـ ِٓ ثٌٍذثةٓ دغّه , ثٌّذجشش ٚثعضخذَ ػذدث ًا ِٓ ثٌظفجةـ , ( cm 20  20 )ٚثدؼجد cm 20  20 )دق١ظ صشىً دّؾّٛػٙج ِذجدال ًا فشثس٠ج ًا دجدؼجد  20 ) فجٌّغجس ثالٚي , ِذ٠ٓ ٌض١جس ثٌٙٛثء ثٚصى٠ٛٓ ِغجس٠ٓ ِضجع ص١جس ثٌٙٛثء ثٌشة١غٟ ثٌّشثد صذش٠ذٖ ٚصؾ١ٙضٖ ٌٍق١ض ٘ٛ ثٌزٞ ٠ّش دٗ ٚ٘زث (دّقضٜٛ سؽٛدٟ عجدش )ف١ظ ٠ذشد صذش٠ذث ًا ِقغٛعج ًا ٚثٌّغجس ثٌغجٟٔ ٠ّش ِٓ , ثٌّغجس ٠غّٝ دجٌّغجس ثٌؾجف ٚثٌشة١غٟ خالٌٗ ثٌٙٛثء ثٌغجٔٛٞ ثٌزٞ ٠ذشد دجٌضذخ١ش ثٌّذجشش ٠ٚغّٝ دجٌّغجس وزٌه ثعضخذَ دثفؼض١ٓ ٌٍٙٛثء ِٚؼخز . ثٌشؽخ ثٚ ثٚ ثٌغجٔٛٞ صذ٠ٚش ثٌّجء ِٕٚفظ ثٚ ٔٛصي ٠مَٛ دٕشش ثٌّجء ػٍٝ ِغجس ص١جس ثٌٙٛثء ثٌغجٔٛٞ ثٌذثخً ِٓ ثعفً ثٌّذجدي ثٌقشثسٞ ف١ذشد صذش٠ذث ًا صذخ١ش٠ج ًا ِذجششث ًا ٚ٘زث دذٚسٖ ٠مَٛ دضذش٠ذ ثٌٙٛثء ثٌّشثد صؾ١ٙضٖ فٟ ف١ٓ ٠طشؿ , ٌٍق١ض ٚ٘ٛ ثٌٙٛثء ثٌّجس دجٌمٕٛثس ثٌؾجفز ٌٍّذجدي ٌمذ صّىٓ ثصٍذجفظ دٙزث ثالعٍٛح ِٓ . ثٌٙٛثء ثٌغجٔٛٞ ثٌّشؽخ ٌٍؾٛ ثعضخذثَ ِذجدي فشثسٞ طفجةقٟ ِظٕغ ِٓ ثٌٍذثةٓ ٌضذش٠ذ ثٌٙٛثء ( 85 % )دجٌضذخ١ش ثٌغ١ش ِذجشش ٚلذ فظً ػٍٝ فؼج١ٌز ِمذثس٘ج ٚدظشٚف ؽ٠ٛز ( m/s 2)ػٕذِج وجٔش عشػز ثٌٙٛثء ثٌشة١غٟ c(  . سؽٛدز ٔغذ١ز ( 30) % دسؽز فشثسر دظٍز ؽجفز ٚ ( 36 ٌمذ ػشف ثٌذجفظ ثٌفجػ١ٍز ٌٍّذجدي ثٌقشثسٞ دجٔٙج ِم١جط الدثء ِٕظِٛز ثٌضذش٠ذ ثٌضذخ١شٞ غ١ش ثٌّذجشش دجعضخذثَ ثٌّذجدي ثٌقشثسٞ ثٌظفجةقٟ ٟٚ٘ ٔغذز ِمذثس ثالٔخفجع فٟ دسؽز فشثسر ثٌٙٛثء ثٌشة١غٟ ٔض١ؾز ثٌضذش٠ذ ثٌّقغٛط ثٌٝ ثٌفشق فٟ دسؽز 124 -115، صفحت 4د ، انؼذ 5 مجهت انخىارزمٍ انهنذسُت انمجهذ ػمبد صذَق محمذ (200 9) 117 ثٌقشثسر ثٌؾجفز ٌٍٙٛثء ثٌشة١غٟ ٚدسؽز فشثسر ثٌذظٍز ثٌشؽذز . ٌٍٙٛثء ثٌغجٔٛٞ ثٌّشؽخ : ٚػذشػٓ ثٌفجػ١ٍز دجٌّؼجدٌز ثالص١ز wtsidtpi dtpodtpi ew    …. (1) ew : ثٌفجػ١ٍز ثالؽّج١ٌز ثٌشؽذز ٌٍّذجدي ثٌقشثسٞ ٚلذ ثعضخذَ ثٌذجفظ ِؼجدالس صذفك فؾ١ّز ٌٍٙٛثء ِجد١ٓ (m 3 /s 0.054 – 0.004 ) ِٓغ عشع ِخضٍفز صشثٚفش د١ (m/s 4 – 0.3 ) ٚالفع ػٕذ ِج صضغ١ش ثٌغشػز صضغ١ش ثٌفجػ١ٍز وّج ثعضٕضؼ ثٌذجفظ ثٔٗ ػٕذ ٚػغ صػجٔف ػٍٝ , دؼاللز ػىغ١ز ثٌغطـ ثٌذثخٍٟ ٌٍظفجةـ ثٌّشىٍز ٌٍّؾشٜ ثٌشة١غٟ ٌٍٙٛثء فجْ ثٌفجػ١ٍز صضدثد ٚرٌه دغذخ فذٚط ثٌذٚثِجس ٌٍٙٛثء دثخً لٕٛثس ٚث٠ؼج ًا لذَ .ثٌّذجدي فضؤدٞ دذٚس٘ج ثٌٝ ص٠جدر ثٔضمجي ثٌقشثسر دسثعز ٚصق١ٍال ًا ٌغذغ ّٔجرػ ِٓ [ 8 ] ( pescod )ثٌذجفظ ثٌّذجدالس ثٌقشثس٠ز رثس طفجةـ ِظٕٛػز ِٓ ثٌٍذثةٓ ِٚضغج٠ٚز فمذ , (cm 20  20  2 )ثالدؼجد دق١ظ ٠ظذـ فؾُ ثٌّذجدي ث٘ضُ دضغ١١ش ثٌشىً ثٌٕٙذعٟ ٌغطـ ثٌظفجةـ ٚثٌّغجفز ثٌذ١ٕ١ز ٌٙج ٚؽذ ثٌذجفظ ثْ ػًّ ثٌٕضؤثس فٟ ثعطـ . ٚثعش٘ج فٟ ثٌفجػ١ٍز ثٌظفجةـ صقغٓ فٟ ثٔضمجي ثٌقشثسر ػذش٘ج ٚوزٌه ٌٙج فجةذر ثخشٜ ف١ظ ثٔٙج صؼًّ وّغجٔذ صؾؼً ثٌٙٛثء ٠ّش فٟ لٕٛثس ِضّجعىز . ِٚضشثطز ِّج صؤدٞ ثٌٝ ص٠جدر ثٌفجػ١ٍز فمذ صٕجٚي دسثعز ثسدؼز ِذجدالس [ 4 ] (chan )ثِج ثٌذجفظ فشثس٠ز ِخضٍفز رثس عطٛؿ صؼطٟ ٔفظ ثالدؼجد ثٌّؼطجر ِٓ لذً (pescod ) ٌٚىٓ دّغجفجس د١ٕ١ز ٚثشىجي عطٛؿ ِضغ١شر , ف١ظ ( mm 3 )صذ١ٓ ثٔٗ ِٓ ثٌّّىٓ ص٠جدر ثٌّغجفز د١ٓ ثٌظفجةـ ِٓ ِٓ دْٚ ثْ ٠ىْٛ ٌٙج صأع١ش ٍِّٛط ػٍٝ ( mm 3.6 )ثٌٝ وّج ٚؽذ ثٌذجفظ ثْ ِؼجٍِز ثٌغطـ , ثالدثء ثٌقشثسٞ ٌٍّذجدي ٠ض٠ذ ِٓ فؼج١ٌز ثٌّذجدي دٕغذز ( colloidal silice )دّقٍٛي دجْ ثٌغطٛؿ ثٌّّذٚدر دشىً "ثعضٕضؼ ث٠ؼج. صمش٠ذج ًا ( 10)% ؽ١ٛح ِغضم١ّز صؼطٟ فؼج١ٌز ٌٍّذجدي ثٌقشثسٞ ثػٍٝ ِٓ ثٌغطٛؿ ثٌّّضذر دشىً ٔضؤثس ِذدذز ٚرٌه ػّٓ فذٚد عشع ِؼ١ٕز ٌٍٙٛثء صؼًّ دجٌذٚسثس ثالٔؼغجؽ١ز دغش ِشثس . ثٌّجس ػذش صٍه ثٌمٕٛثس .صمش٠ذج مكىنبث انجهبز أنمخخبرٌ .2 ٠ضأٌف ؽٙجص ثالخضذجس ِٓ عالعز أؽضثء سة١غ١ز ٟٚ٘ ػٍٝ ثٌّذجدي ثٌقشثسٞ , ِٕظِٛز ص١ٙتز ثٌٙٛثء ثٌخجسؽٟ, ثٌضٛثٌٟ (.1)أٌظفجةقٟ ِٕٚظِٛز صذ٠ٚش ثٌّجء ٚوّج ِٛػـ دجٌشىً منظىمت حهُئت انهىاء انخبرجٍ 2.1 -:ٚصضىْٛ ِٓ ثألؽضثء ثٌضج١ٌز , ِؾشٜ دخٛي ثٌٙٛثء (1 ,ِؾشٜ ثٔقٕجء ثٌٙٛثء (2 .ِؾشٜ خشٚػ ثٌٙٛثء (3 . رسم حخطُطٍ نهمنظىمت انمخخبرَت واجسائهب انمخخهفت 1 -شكم 124 -115، صفحت 4د ، انؼذ 5 مجهت انخىارزمٍ انهنذسُت انمجهذ ػمبد صذَق محمذ (200 9) 118 : انمببدل انحرارٌ أنصفبئحٍ 2.2 صُ صظ١ُّ ٚصظ١ٕغ ِذجدي فشثسٞ طفجةقٟ ِضؼجِذ دقؾُ (cm40 × 30 ×50) َٛف١ظ طٕغ ِٓ طفجةـ عذ١ىز ثأل١ٌّٕ (mg% 10 – al% 90) دغّه(mm 0.5 ) ٚدجألدؼجد (cm30 × 50 ) ٚدؼذ , طف١قز ( 54) ٌىً طف١قز ٠ٚذٍغ ػذد٘ج .رٌه صُ فٕٟ ثٌظفجةـ ٌضى٠ٛٓ صؼش٠ؾجس أٚ أخجد٠ذ غٟ وً طف١قز : منظىمت حذوَر انمبء 2.3 فٟ صٛف١ش ثٌّجء ثٌالصَ ثْ ػًّ ٘زٖ ثٌّٕظِٛز ٠ضٍخض ٌضشؽ١خ عطٛؿ ثٌظفجةـ ِٓ ؽجٔخ ثٌمٕٛثس ثٌّشؽذز ٌٍّذجدي ٠ضُ رٌه . ثٌقشثسٞ ٚدجعضّشثس خالي فضشر ػًّ ِٕظِٛز ثٌضذش٠ذ :دضٛفش عالط ػٕجطش سة١غ١ز ٟ٘ ,شذىز صٛص٠غ ثٌّجء (1 , فٛع صؾ١ّغ ثٌّجء (2 .ِؼخز ثٌّجء (3 اننخبئج وانمنبقشت .3 حأرُر مؼذل حذفق انهىاء 3.1 إْ ٌّؼذي صذفك ثٌٙٛثء ثٌّجس فٟ ِٕظِٛز ثٌضذش٠ذ صأع١شث ًا ف١ظ ثْ ص٠جدر ِؼذي صذفك ثٌٙٛثء صؼٕٟ , وذ١شث ًا ػٍٝ ثدثء ثٌّٕظِٛز ص٠جدر عشػضٗ ٚ٘زٖ دذٚس٘ج صؤعش ػٍٝ ِمذثس ثٔضمجي ثٌقشثسر د١ٓ ٚثعضٕجدث ًا ثٌٝ ثٌّذجدا ثٌؼجِز . (ثٌّجء )ثٌٙٛثء ٚٚعؾ ثٌضذش٠ذ فجٔٗ دض٠جدر عشػز ثٌٙٛثء فجْ , الٔضمجي ثٌقشثسر دجٌضٛط١ً ٚثٌقًّ ثٌفشق فٟ دسؽجس فشثسر ثٌٙٛثء عضمً ٚرٌه ٌٕمظجْ ثٌضِٓ ثٌالصَ ٚثْ ثٌؼىظ طق١ـ فٟ , ٌضذجدي ثٌقشثسر د١ٓ ثٌٙٛثء ٚٚع١ؾ ثٌضذش٠ذ ٌزٌه فجْ عشػز ثٌٙٛثء صشىً ػجِال ًا ِّٙج ًا فٟ ص٠جدر . ٘زٖ ثٌقجٌز .ٚٔمظجْ ثدثء ٚوفجءر ِٕظِٛز ثٌضذش٠ذ كفبءة انخبرَذ ػهً ( va ) َبُن حأرُر سرػت انهىاء انذاخم2 -شكم . ( ηsc )انمحسىش إنً درجت حرارة اننذي نههىاء ثٌؼاللز د١ٓ عشػز ثٌٙٛثء ثٌذثخً ٚوفجءر (2)٠ٛػـ ثٌشىً ثٌضذش٠ذ ثٌٝ دسؽز فشثسر ثٌٕذٜ ٌٍٙٛثء فٟ فجٌز ٚؽٛد ثٌٕشجسر ثٌخشذ١ز ػٍٝ عطٛؿ ثٌّذجدي ِٓ ؽجٔخ ثٌمٕٛثس ثٌّشؽذز ٚوزٌه ٠ٚضؼـ ِٓ ثٌشىً ثْ ثٌؼاللز ػىغ١ز ف١ظ . فٟ فجٌز ػذَ ٚؽٛد٘ج دجصد٠جد عشػز ثٌٙٛثء صمً ثٌىفجءر ٘زٖ ٠ٚشؽغ رٌه ثٌٝ ثٔخفجع ثٌفشق فٟ دسؽز فشثسر ثٌٙٛثء ثٌذثخً ثٌٝ ٚثٌخجسػ ِٓ ِٕظِٛز ثٌضذش٠ذ ػٕذ ص٠جدر ثٌغشػز ٚرٌه الٔٗ دغذٛس فجٌز ثٌٙٛثء ػٕذ ثٌذخٛي ِٚغ عذٛس ِؼذي صذفك ثٌّجء فئْ ص٠جدر ثٌغشػز صمًٍ ِٓ فضشر صالِظ ثٌٙٛثء ِغ طفجةـ ثٌّذجدي ٚثٌّجء ٚدجٌضجٌٟ فجْ ِؼذي ثٔضمجي ثٌقشثسر ِٓ ثٌٙٛثء ثٌٝ ثٌّجء ع١مً ِّج ٠ؤدٞ ثٌٝ ثٔخفجع ٌّٚج وجٔش دسؽز ثٌٕذٜ ٌٍٙٛثء ثٌذثخً , ثٌفشق دسؽز فشثسر ثٌٙٛثء عجدضز ٔض١ؾز عذٛس فجٌز ثٌٙٛثء ػٕذ ثٌذخٛي فئْ ثٌىفجءر ٘زٖ عضمً .ػٕذ ص٠جدر عشػز ثٌٙٛثء (2 )فغخ ثٌؼاللز dpidti dtodti dp    … (2) ٠ٚضذ١ٓ ِٓ ثٌشىً ث٠ؼج ًا ثْ ِؼجٍِز عطٛؿ ثٌّذجدي دّجدر ػٕذِج صىْٛ ( 9 % )ثٌٕشجسر ثٌخشذ١ز صض٠ذ ِٓ ثٌىفجءر دمشثدز ٠ٚالفع ِٓ ثٌشىً ثٔٗ ػٕذ ص٠جدر . ( m/s 2.7 )عشػز ثٌٙٛثء ّْ ثٌىفجءر ( m/s 3.58) ثٌٝ ( m/s 0.35 )عشػز ثٌٙٛثء ِٓ فئ فٟ فجٌز ػذَ ٚؽٛد ( 44.8) % ثٌٝ ( 65.6 % )عضٕخفغ ِٓ ثٌٕشجسر ػٍٝ عطٛؿ ثٌّذجدي ثٌقشثسٞ د١ّٕج صٕخفغ ثٌىفجءر ِٓ فٟ فجٌز ِؼجٍِز ثٌغطٛؿ دجٌٕشجسر ( 52.2) % ثٌٝ ( 69.7)% . ثٌخشذ١ز ٌٕٚفظ ثٌضغ١شثٌغجدك ٌغشػز ثٌٙٛثء ؿٌّٚج وجٔش ثٌٕشجسر ثٌخشذ١ز صؼًّ ػٍٝ ص٠جدر لجد١ٍز عطٛ ثٌّذجدي ػٍٝ ثالفضفجظ دجٌشؽٛدز فؼال ًا ػٓ ص٠جدر ٔغذز صذًٍ ٘زٖ ثٌغطٛؿ دجٌّجء ٌزٌه فٟٙ صقغٓ ِٓ ثٔضمجي ثٌقشثسر ِٓ ثٌٙٛثء ثٌٝ ثٌّجء ٚصض٠ذ ِٓ ثٌفمذ ثٌقشثسٞ ثٌّقغٛط ٌٍٙٛثء ٌزٌه ٚدجٌضجٌٟ ِّٚج . فٟٙ صض٠ذ ِٓ وفجءر ثٌضذش٠ذ ثٌٝ دسؽز فشثسر ٔذٜ ثٌٙٛثء ٠ؾذس روشٖ ثْ ثٌٕشجسر ثٌخغذ١ز صشىً ؽذمز ػجصٌز ػٍٝ عطٛؿ ثٌّذجدي ثٌقشثسٞ ِٓ ؽجٔخ ثٌمٕٛثس ثٌّشؽذز ٚرٌه ٌؼؼف لجد١ٍز ٌٚىٓ ٘زٖ ثٌّمجِٚز , ثٌٕشجسر ثٌخشذ١ز ػٍٝ ثٌضٛثطً ثٌقشثسٞ ثٌقشثس٠ز الصؤعش وغ١شث ًا ػٍٝ ثٔضمجي ثٌقشثسر ٌٍٙٛثء فٟ ثٌمٕٛثس ثٌؾجفز ٚرٌه دغذخ ثٌغّه ثٌم١ًٍ ؽذثًا ٌطذمز ثٌٕشجسر ثٌخشذ١ز ثٌّغط١ز ٌغطٛؿ ثٌّذجدي ِّج ٠ؾؼً ِمجِٚضٙج ٌٍضٛط١ً ل١ٍٍز ؽذث ًا . صىجد ثْ صًّٙ نً كفبءة انخبرَذ ع( va )انذاخم َبُن حأرُر سرػت انهىاء 3 -شكم ηdp ) .( ثٌؼاللز د١ٓ عشػز ثٌٙٛثء ثٌذثخً (3)وّج ٠ٚذ١ٓ ثٌشىً ٚوفجءر ثٌضذش٠ذ ثٌّقغٛط ٚث٠ؼج ًا فٟ فجٌز ٚؽٛد ثٌٕشجسر ثٌخشذ١ز ٠ٚالفع ِٓ ثٌشىً ثْ . ػٍٝ عطٛؿ ثٌّذجدي ٚػذَ ٚؽٛد٘ج ثٌؼاللز ؽشد٠ز د١ّٕٙج ف١ظ دجصد٠جد عشػز ثٌٙٛثء صضدثد وفجءر ٠ٚضذ١ٓ ِٓ ثٌشىً ثْ ِؼجٍِز عطٛؿ ثٌّذجدي . ثٌضذش٠ذ ثٌّقغٛط دّجدر ثٌٕشجسر ثٌخشذ١ز صض٠ذ ِٓ وفجءر ثٌضذش٠ذ ثٌّقغٛط دٕغذز 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 va ( m/s ) 42 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72 η d p % without sawdust with sawdust dti = 42 oc , wti = 21.9 oc qw = 450 l / hr 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 va ( m/s ) 34 36 38 40 42 44 46 48 50 η sc % without sawdust with sawdust dti = 42 oc , w ti = 21.9 oc qw = 450 l / hr 124 -115، صفحت 4د ، انؼذ 5 مجهت انخىارزمٍ انهنذسُت انمجهذ ػمبد صذَق محمذ (200 9) 119 ( . m/s 1.03) صمش٠ذج ًا ػٕذِج صىْٛ عشػز ثٌٙٛثء (10)% ٠ٚالفع ِٓ ثٌشىً ثصد٠جد ثٌىفجءر صذس٠ؾ١ج ًا دجصد٠جد ثٌغشػز ثٌٝ ثْ ٚدؼذ٘ج صذذأ وفجءر ثٌضذش٠ذ , ( m/s 2.7 )صظً ثٌغشػز ل١ّز % )وزٌه ٠الفع ص٠جدر ثٌىفجءر ِٓ . ثٌّقغٛط دجالٔخفجع ( m/s 0.35) ػٕذ صغ١ش ثٌغشػز ِٓ ( 48.1) % ثٌٝ (36.7 ػٕذِج ( 47) % عُ صٕخفغ ل١ّز ثٌىفجءر ثٌٝ (m/s 2.7)ثٌٝ ٚفٟ فجٌز ٚؽٛد ثٌٕشجسر ثٌخشذ١ز . ( m/s 3.58 )صظذـ ثٌغشػز % )ػٍٝ عطٛؿ ثٌّذجدي فجْ وفجءر ثٌضذش٠ذ ثٌّقغٛط صضدثد ِٓ 0.35 ) ػٕذ صغ١ش عشػز ثٌٙٛثء ِٓ ( 49.4) % ثٌٝ (39.1 m/s ) ٌٝث (2.7 m/s ) ٌٝ3.58)ٚػٕذ ص٠جدر ثٌغشػز ث m/s ثْ ٘زٖ ثٌؼاللز ٌىفجءر . ( 47.8) % فجْ ثٌىفجءر صٕخفغ ثٌٝ ( : ثٌضذش٠ذ ثٌّقغٛط ِغ عشػز ثٌٙٛثء ٠ّىٓ صفغ١ش٘ج وجألصٟ ػٕذ عذٛس دسؽز فشثسر ثٌٙٛثء ثٌذثخً ِٓ ف١ظ دسؽز فئْ ص٠جدر , ثٌقشثسر ٚ ثٌشؽٛدز ثٌٕغذ١ز ٚدغذٛس ِؼذي صذفك ثٌّجء عشػز ثٌٙٛثء صمًٍ ِٓ صِٓ ثٔضمجي ثٌقشثسر ِٓ ثٌٙٛثء ثٌٝ ثٌّجء ف١مً ثٌفشق فٟ دسؽز ثٌقشثسر د١ٓ ثٌٙٛثء ثٌذثخً ٚثٌخجسػ ِّج ٠ؤدٞ ثٌٝ صم١ًٍ و١ّز ثٌقشثسر ثٌّقغٛعز ثٌّفمٛدر ٌىً و١ٍٛغشثَ ِٓ ثٌٙٛثء ٚوزٌه فجْ ص٠جدر ثٌغشػز صمًٍ ِٓ صذخش ثٌّجء ٌىً و١ٍٛ غشثَ ِٓ ثٌٙٛثء ثٌؾجف ٚدجٌضجٌٟ فئْ ثٌىغخ ثٌقشثسٞ ثٌىجِٓ ٌٍٙٛثء ثعٕجء صالِغٗ ِغ ثٌّجء فٟ ثٌمٕٛثس ثٌّشؽذز عٛف ٠مً ٚ٘زث دذٚسٖ عٛف ٠مًٍ ِٓ ثٌقضٜٛ ثٌقشثسٞ ٌذخجس ثٌّجء ثٌّمضشْ دىضٍز ٌّٚج وجٔش وفجءر ثٌضذش٠ذ ثٌّقغٛط ِم١جعج ًا ٌّذٜ لذسر , ثٌٙٛثء ِٕظِٛز ثٌضذش٠ذ ػٍٝ صذش٠ذ ثٌٙٛثء صذش٠ذث ًاِقغٛعج ًا فجٔٙج عضضدثد (. 3)دجصد٠جد عشػز ثٌٙٛثء فغخ ثٌؼاللز )( dtodticpm hohi q q cs c cs    … (3) ػهً طبقت انخبرَذ (va)ل َبُن حأرُر سرػت انهىاء انذاخ4 -شكم . ( qc ) نهمنظىمت ٠ٚالفع ِٓ ثٌشىً ثْ ثٌىفجءر صمً ػٕذ ص٠جدر ثٌغشػز ثٌٝ (3.58 m/s ) ٜٛ٠ٚشؽغ رٌه ثٌٝ ثْ ِمذثس ثالٔخفجع فٟ ثٌّقض ثٌقشثسٞ ثٌٕٛػٟ ٌٍٙٛثء ثٌّجس فٟ ثٌّٕظِٛز ٠ظذـ ثلً ِٓ ِمذثس ثالٔخفجع فٟ دسؽز فشثسر ثٌٙٛثء ٚدجٌضجٌٟ وفجءر ثٌضذش٠ذ وّج ٠ٚالفع ص٠جدر ثٌىفجءر فٟ فجٌز ٚؽٛد ثٌٕشجسر . ثٌّقغٛط ثٌخشذ١ز ػٍٝ عطٛؿ ثٌّذجدي ٠ٚشؽغ عذخ رٌه ثٌٝ ثْ ثٌٕشجسر صض٠ذ ِٓ ٔغذز صذًٍ ثٌغطٛؿ دجٌّجء ٚوزٌه ِٓ لجد١ٍضٙج ػٍٝ ػاللز عشػز ثٌٙٛثء (4)٠ٚٛػـ ثٌشىً . ثالفضفجظ دجٌشؽٛدز ثٌذثخً دطجلز ثٌضذش٠ذ ٠ٚضذ١ٓ ثْ ٌؼاللز ؽشد٠ز ف١ظ دجصد٠جد ٚدجٌشغُ ثْ ص٠جدر عشػز ثٌٙٛثء صٕضؼ . ثٌغشػز صضدثد ؽجلز ثٌضذش٠ذ ػٕٙج ص٠جدر فٟ ثٌّقضٜٛ ثٌقشثسٞ ٌٍٙٛثء ثٌخجسػ ِٓ ثٌٍّٕظِٛز إال ثْ ص٠جدر ثٌغشػز صؼٕٟ ص٠جدر و١ّز ثٌٙٛثء ثٌذثخً ٚدجٌضجٌٟ ص٠جدر ٌزٌه فئْ ؽجلز ثٌضذش٠ذ صضدثد دض٠جدر , ِؼذي ثٌضذفك ثٌىضٍٟ ٌٍٙٛثء وّج ٠ٚضذٓ ِٓ ثٌشىً ثْ ِؼجٍِز عطٛؿ ثٌّذجدي . عشػز ثٌٙٛثء ( 16 % )دّجدر ثٌٕشجسر ثٌخشذ١ز صض٠ذ ِٓ ؽجلز ثٌضذش٠ذ دمشثدز ٠ٚالفع ثْ ؽجلز . ( m/s 1.34 )ػٕذِج صىْٛ عشػز ثٌٙٛثء ػٕذِج ( kw 3.08) ثٌٝ ( kw 0.348 )ثٌضذش٠ذ صضدثد ِٓ فٟ فجٌز ( m/s 3.58) ثٌٝ ( m/s 0.35 )صضغ١ش ثٌغشػز ِٓ د١ّٕج صضدث ؽجلز . ػذَ ٚؽٛد ثٌٕشجسر ثٌخشذ١ز ػٍٝ عطٛؿ ثٌّذجدي فٟ فجٌز ِؼجٍِز (kw 3.7) ثٌٝ ( kw 0.391 )ثٌضذش٠ذ ِٓ ثٌغطٛؿ دّجدر ثٌٕشجسر ثٌخشذ١ز ٌٕٚفظ ثٌضغ١ش ثٌغجدك ٌغشػز .ثٌٙٛثء ػهً مؼبمم األداء (v) َبُن حأرُر سرػت انهىاء انذاخم 5 -شكم .( e.e.r ) انحقُقٍ صأع١ش عشػز ثٌٙٛثء ػٍٝ ِؼجًِ ثالدثء (5 )٠ٚذ١ٓ ثٌشىً ٠ٚالفع ثْ ِؼجًِ ثالدثء ٠ضدثد دض٠جدر . ثٌقم١مٟ ٌّٕظِٛز ثٌضذش٠ذ دؼذ٘ج , ( m/s 2.02 )عشػز ثٌٙٛثء ثٌٝ ثْ صظً ثٌغشػز ل١ّز ٠ٚشؽغ رٌه ثٌٝ ثْ ِؼذي ثٌطجلز ثٌّظشٚفز , ٠ذذأ ثالدثء دجٌٕمظجْ ػٍٝ ثٌٙٛثء صىْٛ ثوذش ِٓ فجطً ثٌضذش٠ذ فٟ فجٌز ثسصفجع ل١ّز فئْ (4)ٚدجٌضجٌٟ ٚفغخ ثٌؼاللز ( m/s 2.02 )ثٌغشػز فٛق .ِؼجًِ ثالدثء ٠مً act c p q ree .. … (4) وّج ٠ٚالفع ثْ ثلظٝ صقغٓ فٟ ِؼجًِ ثالدثء ٔض١ؾز ِؼجٍِز صمش٠ذج ًا ػٕذِج ( 12.5 % )عطٛؿ ثٌّذجدي دجٌٕشجسر ثٌخشذ١ز ٠ذٍغ ثْ ثٌؼاللز . ( m/s 1.03 )صىْٛ عشػز ثٌٙٛثء ثٌخجسؽٟ ثٌطشد٠ز ٌّؼجًِ ثالدثء ِغ عشػز ثٌٙٛثء صؼٛد ثٌٝ وْٛ ثٌض٠جدر فٟ فجطً ثٌضذش٠ذ ٔض١ؾز ص٠جدر ِؼذي صذفك ثٌٙٛثء ثوذش ِٓ ثٌض٠جدر ٚصىْٛ , ثٌقجطٍز فٟ ثٌطجلز ثٌّغضٍٙىز ػٍٝ ثٌٙٛثء فٟ ثٌّٕظِٛز وّج ثششٔج عجدمج ًا ثٌٝ ثْ )٘زٖ ثٌؼاللز ػٕذ ل١ُ ِقذٚدر ِٓ ثٌغشػز ثْ ثوذش ل١ّز ٌّؼجًِ ثالدثء ٟ٘ . ( m/s 2.02صظً ثٌغشػز 824.7) ػٕذِج ٠ىْٛ ِؼذي صذفك ثٌٙٛثء ثٌّؾٙض ( 33.5) m 3 /hr ) ٚػٕذِج , فٟ فجٌز ٚؽٛد ثٌٕشجسر ػٍٝ عطٛؿ ثٌّذجدي c 42 )صىْٛ ثٌظشٚف ثٌّٕجخ١ز ِٓ ف١ظ دسؽز ثٌقشثسر o ٌٍذظٍز c 21.9, ثٌؾجفز o ( l / hr 450)ٚدجعضخذثَ ( ٌٍذظٍز ثٌشؽذز . ِٓ ثٌّجء ػاللز عشػز ثٌٙٛثء ِغ ثٌطجلز (6 )٠ٚٛػـ ثٌشىً ٠ٚضذ١ٓ ِٓ ثٌشىً ثْ . ثٌىٙشدجة١ز ثٌّغضٍٙىز فم١م١ج ًا ٌىً ؽٓ صذش٠ذ ٠ٚالفع ثْ . ثٌؼاللز ػىغ١ز ثٌٝ فذٚد ِؼ١ٕز ِٓ عشػز ثٌٙٛثء ثٌطجلز ثٌّغضٍٙىز ٌىً ؽٓ صذش٠ذ صٕخفغ ثٌٝ فذ ِؼ١ٓ ػٕذ ٚطٛي ٚدؼذ٘ج صذذأ دجٌض٠جدر فضٝ ( m/s 2.02 )عشػز ثٌٙٛثء ثٌٝ 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 va ( m / s ) 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 q c ( k w ) without sawdust with sawdust dti = 42 oc , wti = 21.9 oc qw = 450 l / hr 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 va ( m / s ) 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 e .e .r without sawdust with sawdust dti = 42 oc , wti = 21.9 oc qw = 450 l / hr 124 -115، صفحت 4د ، انؼذ 5 مجهت انخىارزمٍ انهنذسُت انمجهذ ػمبد صذَق محمذ (200 9) 120 ف١ظ ثْ ٔغذز ثٌض٠جدر , ( m/s 3.58)ٚطٛي ثٌغشػز ثٌٝ ثٌقجطٍز فٟ ثٌمذسر ثٌّغضٍٙىز صىْٛ ثوذش ِّج صقظً فٟ فجطً ٚفغخ ثٌؼاللز ( m/s 2.02 )ثٌضذش٠ذ ػٕذ ص٠جدر ثٌغشػز فٛق . فئْ ثٌطجلز ثٌّغضٍٙىز ٌىً ؽٓ صذش٠ذ عٛف صضدثد (5) 517.3)( . .  c actact q p ct p ... (5) وّج ٠ٚالفع ثْ ِؼجٍِز ثٌغطٛؿ دّجدر ثٌٕشجسر ثٌخشذ١ز صؤدٞ دجٌشغُ ِٓ ثْ ٚؽٛد , ثٌٝ صم١ًٍ ثٌمذسر ثٌّغضٍٙىز ٌىً ؽٓ صذش٠ذ ثٌٕشجسر ػٍٝ عطٛؿ ثٌّذجدي صض٠ذ ِٓ ِمذثس ثٌٙذٛؽ فٟ ثٌؼغؾ ثالعضجصٟ ٌٍٙٛثء ِّج ٠ؤدٞ ثٌٝ ص٠جدر ثٌطجلز ثٌّظشٚفز ػٍٝ .ٌىٓ ٘زٖ ثٌض٠جدر صشثفمٙج ص٠جدر ثوذش فٟ ؽجلز ثٌضذش٠ذ, ثٌٙٛثء نكم طن حبرَذ ػهً ( va )َبُن حأرُر سرػت انهىاء انذاخم 6-شكم . (.psp )انطبقت اننىػُت انمسخههكت ػهً انطبقت ( va )َبُن حأرُر سرػت انهىاء انذاخم 7-شكم انمسخههكت حقُقُبً صأع١ش عشػز ثٌٙٛثء ثٌذثخً ػٍٝ ثٌطجلز (7 )٠ٚٛػـ ثٌشىً ٠ٚضذ١ٓ ثْ ثٌؼاللز ػىغ١ز د١ّٕٙج . ثٌٕٛػ١ز ثٌّغضٍٙىز فٟ ثٌّٕظِٛز ٠ٚالفع ص٠جدر ثٌطجلز . ف١ظ دجصد٠جد ثٌغشػز صمً ثٌطجلز ثٌٕٛػ١ز ( m/s 3.58 )ثٌٕٛػ١ز ثٌّغضٍٙىز ػٕذِج صظً عشػز ثٌٙٛثء ثٌٝ ٠ٚشؽغ شىً ٘زٖ ثٌؼاللز ثٌٝ ثْ ص٠جدر عشػز ثٌٙٛثء صؤدٞ ثٌٝ , ص٠جدر ثٌطجلز ثٌّظشٚفز ػٍٝ ثٌٙٛثء دٕغذز ثلً ِٓ ثٌض٠جدر ثٌضٟ فئْ (6 )ف١ظ فغخ ثٌؼاللز , صقظً فٟ ِؼذي صذفك ثٌٙٛثء . ثٌطجلز ثٌٕٛػ١ز ثٌّغضٍٙىز صضٕجعخ ػىغ١ج ًا ِغ صذفك ثٌٙٛثء aactsp mpp   / . … (6) فئْ ( m/s 3.58 )ٌىٓ دٛطٛي عشػز ثٌٙٛثء ثٌٝ ثٌم١ّز ٔغذز ثٌض٠جدر فٟ ثٌطجلز ثٌّظشٚفز صظذـ ثوذش ِٓ ٔغذز ثٌض٠جدر فٟ ٌزٌه فئْ , ِؼذي صذفك ثٌٙٛثء ٚثٌٕجصؼ ػٓ ص٠جدر عشػز ثٌٙٛثء ٠ٚالفع ثْ ِؼجٍِز ثٌغطٛؿ . ثٌطجلز ثٌٕٛػ١ز ثٌّغضٍٙىز صضدثد دّجدر ثٌٕشجسر ثٌخشذ١ز صض٠ذ ِٓ ثٌطجلز ثٌٕٛػ١ز ثٌّغضٍٙىز دمشثدز ٠ٚؼٛد رٌه ثٌٝ ثْ (m/s 2.7) ػٕذِج صىْٛ ثٌغشػز ( 12)% ثٌٕشجسر صض٠ذ ِٓ خشٛٔز ثٌغطٛؿ ِّج ٠ض٠ذ ِٓ ِؼجًِ ثالفضىجن ٌٙزٖ ثٌغطٛؿ ِٚمذثس ثٌٙذٛؽ فٟ ػغؾ ثٌٙٛثء ٚدجٌضجٌٟ صىْٛ ثٌطجلز ثٌّظشٚفز ػٍٝ ثٌٙٛثء ثوذش ِج ٌٛ وجٔش ثٌٕشجسر غ١ش . ِٛؽٛدر ػٍٝ عطٛؿ ثٌظفجةـ ٌٕٚفظ ثٌم١ُ ٌّؼذالس صذفك ثٌٙٛثء ٠ضذ١ٓ إْ أفؼً ِؼذي ٌٍٙٛثء ٠ّىٓ ثْ (7,3 )ِٓ ثإلشىجي أٞ ػٕذِج صىْٛ ( m / hr 824.7 ) صؾٙضٖ ِٕظِٛز ثٌضذش٠ذ ٟ٘ ف١ظ ػٕذ ٘زث ثٌضذفك ٠ىْٛ ( m/s 2.02 )عشػز ثٌٙٛثء ٌذثخً ٚدجػضّجد فجٌز ٚؽٛد ثٌٕشجسر . ثدثء ثٌّٕظِٛز ثفؼً ِج٠ّىٓ ثٌخشذ١ز ػٍٝ عطٛؿ ثٌظفجةـ فئْ ِؼجًِ ثالدثء ثٌقم١مٟ ٌٍّٕظِٛز فٟ ف١ٓ صىْٛ ثٌمذسر ثٌىٙشدجة١ز ثٌّغضٍٙىز ٌىً ( 33.5 )٠ىْٛ ٚثٌطجلز ثٌٕٛػ١ز ثٌّغضٍٙىز ٌىً , (kw / ton 0.105)ؽٓ صذش٠ذ (4.7 w.min / kgdry air ) ثْ فجٌز ثٌٙٛثء ثٌّؾٙض ِٓ لذً ِٕظِٛز ثٌضذش٠ذ ِٓ ف١ظ c 22.8 )دسؽز ثٌقشثسر صىْٛ o c 18.8 ) ٌٍذظٍز ثٌؾجفز ٚ( o ) ثْ ٘زٖ ثٌم١ُ ثٌّقظٌٛز ٟ٘ ػٕذِج صىْٛ . ٌٍذظٍز ثٌشؽذز : ثٌظشٚف ثٌضشغ١ٍ١ز وجالصٟ (dti = 42 c o , wti = 21.9 c o , qw = 450 l / hr , qa = 824.7 m 3 / hr ) فئْ ِؼجًِ ( m/s 3.2 ) ثٌٝ ( m/s 3 )ثٌٙٛثء ثٌذثخً ِٓ فٟ ف١ٓ ( 27.5 ) ثٌٝ ( 28.3 )ثالدثء ٌٍّٕظِٛز ٠ضٕجلض ِٓ ) ثٌٝ ( 31.2 )٠ضٕجلض ِؼجًِ ثدثء ِٕظِٛز ثٌضذش٠ذ ثٌقج١ٌز ِٓ إْ ظشٚف . ٌٕفظ ثٌضغ١ش ثٌّزوٛس فٟ عشػز ثٌٙٛثء ( 29.6 ثٌضشغ١ً ثٌضٟ ثػضّذ٘ج شّؼْٛ فٟ دسثعضٗ وجٔش ِمجسدز ٌٍظشٚف ف١ظ ثعضخذَ شّؼْٛ ٘ٛثء خجسؽٟ , ثٌّؼضّذر فٟ ثٌذقظ ثٌقجٌٟ .ٔمٟ دجٌىجًِ ٌضذش٠ذٖ ػٍٝ ِشفٍض١ٓ حأرُر انهبىط فٍ انضغظ االسخبحٍ نههىاء 3.2 إْ ثٌٙذٛؽ فٟ ػغؾ ثٌغىْٛ ٌٍٙٛثء ٠ؼذ ِٓ ثٌّضغ١شثس ثٌشة١غ١ز ٚثٌّّٙز فٟ صظ١ُّ ِٕظِٛز ثٌضذش٠ذ فؼال ًا ػٓ ثٌّذجدالس ف١ظ ٠ؼضذش ٘زث ثٌّضغ١ش ِؤششث ًا ٌٍخغجسر ثٌقجطٍز فٟ , ثٌقشثس٠ز ثٌطجلز ثٌّظشٚفز ػٍٝ ثٌّجةغ ِٓ ثؽً ثٌضغٍخ ػٍٝ لٜٛ ثالفضىجن ثٌّؼشلٍز ٌؾش٠جْ ثٌّجةغ ػذش ثٌّٕظِٛز ثٌّؼ١ٕز ٚثٌضٟ دذٚس٘ج صغذخ .٘زث ثٌٙذٛؽ فٟ ػغؾ ثٌّجةغ ثٌؼاللز ثٌؼ١ٍّز د١ٓ صذفك ثٌٙٛثء ثٌذثخً (8)٠ٚٛػـ ثٌشىً ٚثٌٙذٛؽ فٟ ػغؾ ثٌٙٛثء ٚرٌه لذً ِؼجٍِز عطٛؿ ثٌّذجدي دّجدر ٠ٚضذ١ٓ ِٓ ثٌشىً ثْ ثٌؼاللز ؽشد٠ز ٚوزٌه . ثٌٕشجسر ثٌخشذ١ز ٠الفع ثْ ثٌٙذٛؽ فٟ ػغؾ ثٌٙٛثء فٟ ثٌمٕٛثس ثٌّشؽذز ثوذش ِّج ٠ٚشؽغ , ٘ٛ فٟ ثٌمٕٛثس ثٌؾجفز ػٓ ثٌم١ُ ٔفغٙج ِٓ صذفك ثٌٙٛثء عذخ رٌه ثٌٝ طغش ثٌّغجفز ثٌذ١ٕ١ز ٌٍّّشثس ثٌّشؽذز ٔغذز ًا إٌٝ ثٌّّشثس ثٌؾجفز فؼال ًا ػٓ ٚؽٛد ثالٔقٕجءثس ثٌّٛؽٗ ٌض١جس ثٌٙٛثء فٟ ثٌمٕٛثس ثٌّشؽذز ف١ظ صض٠ذ ِٓ ِؼجًِ ثالفضىجن ثٌغطقٟ فٟ ؽجٔخ ثٌمٕٛثس ثٌّشؽذز ٚوزٌه ٚؽٛد وضٍز ثٌّجء ثٌّششٛشز فٟ ٘زٖ وً رٌه ٠ؾؼً ِٓ ثْ صىْٛ ل١ُ , ثٌمٕٛثس صؼشلً ِٓ ؽش٠جْ ثٌٙٛثء ٘ذٛؽ ثٌؼغؾ ٌٍٙٛثء ٔض١ؾز ِشٚسٖ فٟ ثٌمٕٛثس ثٌّشؽذز صؼٍٛ ػٓ 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 va ( m / s ) 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 p a ct . / t .c ( k w / t o n ) without sawdust with sawdust dti = 42 oc , wti = 21.9 oc qw = 450 l / hr 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 va ( m / s ) 2 4 6 8 10 12 14 16 p sp . ( w . m in / k g d ry a ir ) without sawdust with sawdust dti = 42 oc , wti = 21.9 oc qw = 450 l / hr 124 -115، صفحت 4د ، انؼذ 5 مجهت انخىارزمٍ انهنذسُت انمجهذ ػمبد صذَق محمذ (200 9) 121 ٘ذٛؽ ثٌؼغؾ فٟ ثٌمٕٛثس ثٌؾجفز ٠ّٚىٓ ثعذجس رٌه ث٠ؼج ًا ِٓ خالي ثٌؼاللز ثٌضج١ٌز ٌّمذثس ثالٔخفجع فٟ ػغؾ ثٌٙٛثء ثٌّجس فٟ : ٟٚ٘ [ 9]ِؾشٜ ِغضط١ً ثٌّمطغ ٚثٌّزوٛس فٟ ثٌّظذس 2v dh l fp a   … (7) ٠ٚظٙش ؽ١ٍج ًا ٌٍؼ١جْ ِٓ ثٌّؼجدٌز أػالٖ ثْ ٘ذٛؽ ثٌؼغؾ ٠ضٕجعخ صٕجعذج ًا ؽشد٠ج ًا ِغ ِشدغ عشػز ثٌٙٛثء ِٚؼجًِ ثالفضىجن ِٚٓ ٕ٘ج ٠ّىٓ , ثٌغطقٟ ٚػىغ١ج ًا ِغ ثٌمطش ث١ٌٙذس١ٌٚىٟ ٌٍمٕجر m/s 1 ) ػٓ صفغ١ش ِج ٠قظً ٌٙذٛؽ ثٌؼغؾ ػٕذ ص٠جدر ثٌغشػز . ٌٚٛ دٕغذز ل١ٍٍز فجٔٙج صؤدٞ ثٌٝ ص٠جدر ٘ذٛؽ ثٌؼغؾ دٕغذز ثوذش ( ٌّٚج وجْ ِؼجًِ ثالفضىجن ٌٍغطٛؿ ثٌّضّٛؽز ثوذش ِٓ ل١ُ ِؼجًِ ثالفضىجن ٌٍغطٛؿ ثٌّغض٠ٛز ٚث٠ؼج ًا ٌّج وجْ ثٌمطش ث١ٌٙذس١ٌٚىٟ ثطغش ِّج ٌٍمٕٛثس ثٌؾجفز( mm 11.86 )ٌٍمٕٛثس ثٌّشؽذز (15.59 mm)فئْ ِمذثس ثالٔخفجع ( 7) ٌزٌه ٚفغخ ثٌؼاللز فٟ ػغؾ ثٌٙٛثء فٟ ثٌمٕٛثس ثٌّشؽذز ع١ىْٛ ثوذش ِّج فٟ . ثٌمٕٛثس ثٌؾجفز انبحىد انسببقت من َبُن مقبرنت نخبئج انبحذ انحبنٍ مغ 8 -شكم .حُذ مؼبمم األداء من َبُن مقبرنت نخبئج انبحذ انحبنٍ مغ انبحىد انسببقت 9 -شكم .حُذ انطبقت انمسخههكت حقُقب نكم طن حبرَذ ثٌؼاللز ثٌؼ١ٍّز د١ٓ ِؼذي صذفك ثٌٙٛثء (9)وّج ٠ٚذ١ٓ ثٌشىً ٚثٌٙذٛؽ فٟ ثٌؼغؾ ٌٚىٓ دؼذ ِؼجٍِز عطٛؿ ثٌّذجدي دّجدر ٠ٚظٙش ِٓ ثٌشىً . ثٌٕشجسر ثٌخشذ١ز ِٓ ؽجٔخ ثٌمٕٛثس ثٌّشؽذز ٠ٚالفع ثْ ل١ُ ٘ذٛؽ ( 8)ثْ ثٌؼاللز ِشجدٙز ٌّج فٟ ثٌشىً ٌٕٚفظ (8)ثٌؼغؾ فٟ ٘زٖ ثٌقجٌز صؼٍٛ ػّج ٟ٘ ػ١ٍٗ فٟ ثٌشىً ثٌم١ُ ِٓ ِؼذي صذفك ثٌٙٛثء ٠ٚشؽغ رٌه ثٌٝ ؽذمز ثٌٕشجسر ثٌّغط١ز العطـ ثٌظفجةـ ِٓ ؽجٔخ ثٌمٕٛثس ثٌّشؽذز ف١ظ صض٠ذ ِٓ ل١ّز فئْ ِمذثس ثٌٙذٛؽ ( 7)ِؼجًِ ثالفضىجن ٚدجٌضجٌٟ ٚفغخ ثٌّؼجدٌز وّج ٚع١الفع ثْ ثلظٝ ص٠جدر فٟ ٘ذٛؽ . فٟ ػغؾ ثٌٙٛثء ع١ضدثد ( % 39 )ثٌؼغؾ ٔض١ؾز ِؼجٍِز ثٌغطٛؿ دجٌٕشجسر ٠ىْٛ دمشثدز صمش٠ذج ًا ِٓ ِٕظِٛز ( % 21 )فٟ ثٌمٕٛثس ثٌّشؽذز ٚدٕغذز m 824.7 )ثٌضذش٠ذ وىً ػٕذِج ٠ىْٛ ِؼذي صذفك ثٌٙٛثء 3 / hr ) . ( l / hr 450 )ِٚؼذي صذفك ثٌّجء ٚث٠ؼج ًا ٠ضذ١ٓ ثْ ل١ُ ٘ذٛؽ ثٌؼغؾ فٟ ثٌمٕٛثس ثٌؾجفز صىْٛ ٚرٌه ٌؼذَ (9, 8)ِضمجسدز فٟ ثٌقجٌض١ٓ ثٌّٛػقض١ٓ دجٌشى١ٍٓ . فذٚط أٞ صغ١ش فٟ ٘زٖ ثٌمٕٛثس فٟ وٍضج ثٌقجٌض١ٓ حبرُر مؼبمم انخقبل انحرارة 3.3 ثْ ِؼجًِ ثٔضمجي ثٌقشثسر فٟ أٞ ِٛػغ ِٓ عطـ طف١قز ِؼشػز ٌض١جس ٘ٛثةٟ ٠ضٛلف ػٍٝ ؽذ١ؼز ثٌؾش٠جْ ثٌٕجشب ػٍٝ ثٌغطـ فؼال ًا ػٓ خٛثص ثٌض١جس ثٌٙٛثةٟ ٚؽذ١ؼز ثٌغطـ رثصٗ ِٓ ٚغ١ش٘ج ِٓ ثٌؼٛثًِ ثٌؼذ٠ذر ثٌّؤعشر فٟ , ف١ظ ثٌشىً ثٌٕٙذعٟ ٌّٚج وجْ ِؼجًِ ثٔضمجي ثٌقشثسر ِؤششث ًا . ل١ّز ثٔضمجي ثٌقشثسر ِّٙج ًا فٟ صم١ُ وفجءر ٚثدثء ثٌّذجدالس ثٌقشثس٠ز ٌزث فمذ صُ فغجح ِؼجًِ ثٔضمجي ثٌقشثسر دجٌقًّ ػذش ثٌطذمز ثٌغشجة١ز ِٓ ثٌٙٛثء ٠ٚٛػـ ثٌشىً , ثٌّالِغز العطـ طفجةـ ثٌّذجدي ثٌقشثسٞ ثٌؼاللز ثٌؼ١ٍّز د١ٓ عشػز ثٌذثخً ثٌٝ ِٕظِٛز ثٌضذش٠ذ (10) ِٚؼجًِ ثٔضمجي ثٌقشثسر دجٌقًّ ٌٍٙٛثء فٟ ثٌمٕٛثس ثٌؾجفز ٠ٚضذ١ٓ ِٓ ثٌشىً ثْ . ٚثٌّشؽذز ِٓ ثٌّذجدي ثٌقشثسٞ ثٌظفجةقٟ ثٌؼاللز ؽشد٠ز ف١الفع ثصد٠جد صذس٠ؾٟ ٌّؼجًِ ثٔضمجي ثٌقشثسٞ ِغ وّج ٠ٚضذ١ٓ ثْ ل١ُ ِؼجًِ ثٔضمجي ثٌقشثسر ٌٍٙٛثء فٟ . ص٠جدر ثٌغشػز ثٌمٕٛثس ثٌّشؽذز صؼٍٛ ػٓ صٍه ثٌضٟ ٌٍٙٛثء فٟ ثٌمٕٛثس ثٌؾجفز . ( m / s 1.03 )ٚدشىً وذ١ش خجطز ػٕذ ص٠جدر ل١ُ ثٌغشػز ػٓ ٠شؽغ عذخ ٘زٖ ثٌؼاللز ثٌٝ ثْ ص٠جدر عشػز ثٌٙٛثء صؤدٞ ثٌٝ ص٠جدر ٔغذز ثالػطشثح ٚثٌذٚثِجس ثٌٕجشتز ػٕذ ِالِغز ثٌٙٛثء وّج ٠ٚؼٛد عذخ ثسصفجع ل١ُ ِؼجًِ ثٔضمجي , العطـ طفجةـ ثٌّذجدي ثٌقشثسر ٌٍٙٛثء فٟ ثٌمٕٛثس ثٌّشؽذز ػٓ صٍه ثٌضٟ ٌٍمٕٛثس ثٌؾجفز ثٌٝ ػ١ك ثٌمٕٛثس ثٌّشؽذز ِمجسٔز ِغ ثٌمٕٛثس ثٌؾجفز ٚوزٌه ثٌضّٛؽجس ثٌّشىٍز ِٓ فٕٟ طفجةـ ثٌّذجدي ٚثٌضٟ صىْٛ ِٛثؽٙز ٌض١جس ثٌٙٛثء ثٌّجس فٟ ثٌمٕٛثس ثٌّشؽذز أٞ ثٔٙج صىْٛ ػّٛد٠ز ػٍٝ ٚثْ ٘زٖ ثٌضّٛؽجس دذٚس٘ج صؼًّ ػٍٝ ص٠جدر , ثصؾجٖ ِغجس ثٌٙٛثء ثالػطشثح ٚثٌذٚثِجس فٟ ص١جس ثٌٙٛثء ٚدجٌضجٌٟ فئْ ِؼجًِ ثٔضمجي ثٌقشثسر فٟ ؽجٔخ ثٌمٕٛثس ثٌّشؽذز ٠ىْٛ ثوذش ِّج فٟ ؽجٔخ . ثٌمٕٛثس ثٌؾجفز 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 va ( m / s ) 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 p a ct . / t .c ( k w / t o n ) experimental shamaoon [32] 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 va ( m / s ) 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 e .e .r experimental shamaoon [32] 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 va ( m/s ) 0 20 40 60 80 100 120 140 160 h a ( w / m 2 . o c ) ha dry channels ha wet channels dti = 42 oc wti = 21.9 oc qw = 450 l / hr 124 -115، صفحت 4د ، انؼذ 5 مجهت انخىارزمٍ انهنذسُت انمجهذ ػمبد صذَق محمذ (200 9) 122 ومؼبمم va ))َبُن انؼالقت بُن سرػت انهىاء انذاخم ػذد 10 -شكم نههىاء فٍ قنىاث انمببدل انحرارٌ ( ha )انخقبل انحرارة ببنحمم ػالقت ػذد رَنىنذ وػذد نسهج 3.4 ثٌؼاللز ثٌؼذد٠ز د١ٓ ػذد س٠ٌٕٛذ ٚػذد ( 11)٠ٛػـ ثٌشىً ٔغٍش ٌٍٙٛثء فٟ ثٌمٕٛثس ثٌؾجفز ٚثٌمٕٛثس ثٌّشؽذز ِٓ ثٌّذجدي ٠ٚضذٓ ِٓ ثٌشىً ثْ ثٌؼاللز ؽشد٠ز ف١ظ . ثٌقشثسٞ ثٌظفجةقٟ ٌّٚج وجْ ػذد س٠ٌٕٛذ ٠ضٛلف . دض٠جدر ػذد س٠ٌٕٛذ ٠ضدثد ػذد ٔغٍش ػٍٝ عشػز ثٌٙٛثء فٟ لٕٛثس ثٌّذجدي ٌزث فئْ ص٠جدصٗ صؼٕٟ ص٠جدر عشػز ثٌٙٛثء ٚدجٌضجٌٟ ص٠جدر ِؼجًِ ثٔضمجي ثٌقشثسر ٌزٌه فئْ ػذد ٠ٚالفع ِٓ ثٌشىً ثْ ل١ُ ػذد س٠ٌٕٛذ فٟ . . ٔغٍش عٛف ٠ضدثد ثٌمٕٛثس ثٌّشؽذز ثطغش ِّج فٟ ثٌمٕٛثس ثٌؾجفز ٚرٌه ٠شؽغ ثٌٝ ثْ ِٓ صٍه ثٌضٟ ٌٍمٕٛثس ثٌؾجفز ِغجفز ِمطغ ثٌمٕٛثس ثٌّشؽذز ثوذش ِّج ٠ؾؼً عشػز ثٌٙٛثء فٟ ثٌمٕٛثس ثٌّشؽذز صىْٛ ثلً ِٓ .ثٌغشػز فٟ ثٌمٕٛثس ثٌؾجفز نههىاء فٍ nu)) مغ نسهج re))َبُن ػالقت ػذد رَنىنذ 11 -شكم .قنىاث انمببدل االسخنخبجبث .4 أظٙشس ثٌٕضجةؼ ثٌؼ١ٍّز أْ أفؼً و١ّز ٌٍٙٛثء ٠ّىٓ .1 m 824.7 )صؾ١ٙض٘ج ِٓ لذً ِذشدر ثٌٙٛثء ٟ٘ 3 / hr ) . أْ ِؼجٍِز عطٛؿ ثٌّذجدي ثٌقشثسٞ دٕشجسر ثٌخشخ صقغٓ .2 ٌىٕٙج , ( % 10 )ِٓ وفجءر ٚأدثء ِذشدر ثٌٙٛثء دمشثدز )صض٠ذ ِٓ ِمذثس ثٌٙذٛؽ فٟ ثٌؼغؾ ثالعضجصٟ ٌٍٙٛثء دٕغذز فضٕضؼ ػٓ رٌه ص٠جدر فٟ ثٌطجلز ثٌّغضٍٙىز , صمش٠ذجًا ( % 21 . ( % 9 )دّج ٠مجسح ػذَ إِىج١ٔز ثعضخذثَ ِذشدر ثٌٙٛثء فٟ ثٌّٕجؽك ثٌضٟ ٠ض٠ذ .3 / g moisture 11.9 )ف١ٙج ثٌّقضٜٛ ثٌشؽٛدٟ ٌٍٙٛثء ػٓ kg dry air ). نمسخخذمتانرمىز ا انىحذاث انمؼنًانرمس cpm ثٌقشثسر ثٌٕٛػ١ز ٌٍٙٛثءkj / kg dry ثٌشؽخ air . c  dh ثٌمطش ث١ٌٙذس١ٌٚىٟ ٌمٕٛثس ثٌّذجدي ثٌقشثسٞ mm dp ٜدسؽز فشثسر ٔمطز ثٌٕذ ٌٍٙٛثء c  dt دسؽز فشثسر ثٌذظٍز ثٌؾجفز ٌٍٙٛثء co e.e.r ٔغذز وفجءر ثٌطجلز( (ِؼجًِ ثألدثء ثٌقم١مٟ f ِٟؼجًِ ثالفضىجن ثٌغطق h ثٌّقضٜٛ ثٌقشثسٞ ٌٍٙٛثء ثٌشؽخ kj / kg dry air ha ِؼجًِ ثٔضمجي ثٌقشثسر دجٌقًّ ٌٍٙٛثء w / m2 . co l ؽٛي ثٌمٕجر ٌٍّذجدي ثٌقشثسٞ mm ma ِؼذي ثٌضذفك ثٌىضٍٟ ٌٍٙٛثءkg dry air / s ( δt ) a w ثٌفشق د١ٓ ِضٛعؾ دسؽز فشثسر ثٌٙٛثء دثخً ثٌمٕٛثس ثٌؾجفز ِٚضٛعؾ دسؽز فشثسر ثٌّجء co nu ٟػذد ٔغٍش ٌٍٙٛثء ف لٕٛثس ثٌّذجدي ثٌقشثسٞ p ثٌؼغؾ ثٌؾضةٟ ٌذخجس ثٌّجء فٟ ثٌٙٛثء ثٌشؽخ n / m2 pa ثٌؼغؾ ثٌؾضةٟ ٌٍٙٛثء ثٌؾجف فٟ ثٌٙٛثء ثٌشؽخ n / m2 pact. ثٌطجلز ثٌّظشٚفز فم١م١جًا ػٍٝ ثٌٙٛثء kw pact. / t.c ثٌطجلز ثٌىٙشدجة١ز ثٌّغضٍٙىز فم١م١جًا ٌىً ؽٓ صذش٠ذ kw / ton psp. ثٌطجلز ثٌٕٛػ١ز ثٌّغضٍٙىزw.min / kg dry air qa ِّٟؼذي ثٌضذفك ثٌقؾ ٌٍٙٛثء m3 / s qc و١ّز )ؽجلز ثٌضذش٠ذ ثٌقشثسر ثٌّفمٛدر ِٓ (ثٌٙٛثء kw qcs ؽجلز ثٌضذش٠ذ ثٌّقغٛعزkw qw ِّٟؼذي ثٌضذفك ثٌقؾ ٌٍّجء l / hr s ػشع ثٌمٕجر ٌٍّذجدي ثٌقشثسٞ mm v* عشػز ثٌٙٛثء دثخً لٕٛثس ثٌّذجدي ثٌقشثسٞ m / s va ِضٛعؾ عشػز ثٌٙٛثء ثٌذثخً إٌٝ ثٌّٕظِٛز m / s re n u 0 1000 2000 3000 4000 5000 6000 7000 0 10 20 30 40 50 60 70 air in dry channels air in wet channels dti = 42 oc wti = 21.9 oc qw = 450 l / hr 124 -115، صفحت 4د ، انؼذ 5 مجهت انخىارزمٍ انهنذسُت انمجهذ ػمبد صذَق محمذ (200 9) 123 w ثٌّقضٜٛ ثٌشؽٛدٟ ٌٍٙٛثءkg moisture/kg dry air w.p.p ثٌمذسر ثٌىٙشدجة١ز ثٌّغضٍٙىز ِٓ لذً ِؼخز ثٌّجء kw انمصبدر. 5 [1] gonzales , d.j. ; " the scince and application of evaporative cooling " , american industrial hygiene association journal , vol.27,march – april 1966 , pp. 172 – 179 . [2] kennedy , r.a. " a two-stage evaporative coolers " m.sc. thesis , university of texas , austin , tex. , may 1953 , pp. 32 – 38 . ثٌضذش٠ذ ثٌضذخ١شٞ ٌضى١١ف ثٌٙٛثء " دٚٔجي ؽذشثة١ً , شّؼْٛ [3] , ثٌؾجِؼز ثٌضىٌٕٛٛؽ١ز , سعجٌز ِجؽغض١ش " ػٍٝ ِشفٍض١ٓ . 1989أ٠ٍٛي [4] chan , c.y.l. ; "performance test of model plate heat exchanger with wetted plates " csiro division of mechanical engineering , internal report no.120 victoria , australia , march 1973 , pp. 1 – 6 . دسثعز ػ١ٍّز ػٓ إِىج١ٔز ص٠جدر " ؽجٌخ وشجػ , ِشصؼٝ [5] سعجٌز ددٍَٛ ػجٌٟ " وفجءر ِذشدثس ثٌٙٛثء ثٌضؾجس٠ز ثٌّذجششر آرثس , ثٌؾجِؼز ثٌضىٌٕٛٛؽ١ز , 1980 . [6] al – khatib , a.m.j. " an investigation in to the effect of precooling water on the performance of evaporative air cooling " m.s.c thesis , university of baghdad , january 1984 . [7] pescod , d. , " unit air cooler using plastic heat exchanger with evaporatively cooled plates " australian refrigeration , air conditioning and heating , vol.22 , no.9 , sept. 1968 , pp. 22 – 26 [8] pescod , d. , " effect of turbulance promoters on the performance of plate heat exchangers " heat exchangers : design & theory sourcebook , mc graw – hill , new york , 1974 , ch. 22 , pp. 601 – 615 . [9] ihve guide " flow of fluids in pipes and ducts " , ch.4 , 49 cadogan square loud swlxojb,1977. imaad sedeeq mohammed al-khwarizmi engineering journal, vol. 5, no. 4, pp 115-124 (2009) 124 performance estimation of heat exchanger operates by evaporative cooling manner imaad sedeeq mohammed salah karem juaad department of engineering/ university of technology abstract : in this study the design and installation of evaporative air cooler was carried out using completely outdoor air (fresh air) according to two stage evaporative cooling principle. the laboratory equipment was installed by designing and manufacturing a cross flow plate heat exchanger, where aluminum plates used for this purpose with dimensions (50 × 30 × 40 cm). the surfaces of heat exchanger were covered by sawdust from wetted channels side, to increase the percentage of wetting these surfaces and hence improve the performance and efficiency of air cooler. an experimental study was carried out to estimate the performance of cooling system, where some of the dominant effective parameters were studied like air flow rate and flow rate and effect the static pressure drop of air and the heat transfer of performance .air flow rate was ranged between (142.90 to 1461.50 m3 / hr) and water flow rate was varied from (144 l / hr) to (1050 l / hr). the experimental results showed that the optimum flow rate of air prepared by the air cooler is (824.7 m3 / hr), as it to be seen from the study that treating the heat exchanger surfaces by sawdust improves the air cooler efficiency about (10 %), but in the other hand leads to increase the static pressure drop in proportion (21%) approximately, and hence increase consumed power about (9 %).the results also show the air cooler can not be used in regions that have moisture content accedes (11.90 g moisture/kg dry air). <4d6963726f736f667420576f7264202d20312d3134c7e1c7c120e6dad5e3c7e420e6c7e3edd1> al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 16, no. 2, june, (2020) p. p. 113 wearable detection systems for epileptic seizure: a review alla fikrat alwindawi* osman nuri uçan** ameer hussein morad*** *,**school of engineering and natural sciences/ altinbas university/ istanbul/ turkey ***department of information and communication engineering/ al-khwarizmi college of engineering/ university of baghdad *email: alla.alwindawi92@gmail.com **email: osman.usan@altinbas.edu.tr ***email: ameer@kecbu.uobagdad.edu.iq )received 24 july 2019; accepted 15 march 2020( .0013https://doi.org/10.22153/kej.2020.0 abstract the seizure epilepsy is risky because it happens randomly and leads to death in some cases. the standard epileptic seizures monitoring system involves video/eeg (electro-encephalography), which bothers the patient, as eeg electrodes are attached to the patient’s head. seriously, helping or alerting the patient before the seizure is one of the issue that attracts the researchers and designers attention. so that there are spectrums of portable seizure detection systems available in markets which are based on non-eeg signal. the aim of this article is to provide a literature survey for the latest articles that cover many issues in the field of designing portable real-time seizure detection that includes the use of multiple body signals, new algorithm methods, and detection devices that are commercially available. as a result, the reviewing process shows that there are many research articles that have covered wearable seizure detection systems that based on body signals. the more effective monitoring and detection seizure system is the system that uses multi-body signals, is highly comfortable and has low power consumption. keywords: biosensors, wearable sensors, epilepsy, seizures, non-eeg, emg. 1. introduction since the 70’s, medical specialists have envisioned intelligent, implantable devices for predicting seizures and triggering abortive treatment to aid many people all over the world who have medically intractable epilepsy. most of the researcher used the seizure detection method based on the eeg –recordings that require, either an invasive recording (intra-cranial electrodes) or placing numerous scalp electrodes, which are less stable over time. moreover, the patient can get uncomfortable wearing electrodes on their scalp, due to the fact that they are very obvious for others. despite the eeg approach being the standard; it does not necessarily seem as the optimal choice for a seizure alarm outside the hospital, so other researches tried to find a new different method to predict the seizure [1-3]. the research presented a review of researches that used non-eeg signals, such as electromyography (emg), heart rate (hr), oxygen level (spo2), accelerometer (acm), and body temperature. it also prepared a list of latest of available commercial devices for epileptic detection. the aim of this work is to present useful information to assisted researchers in the field. alla fikrat alwindawi al-khwarizmi engineering journal, vol. 16, no. 2, p.p. 113 (2020) 2 2. epilepsy epilepsy can be defined as a brain disorder identified via an enduring pre-disposition for the generation of epileptic seizures and via the physiological, neuro-biological, cognitive, and social results of this disorder. defining epilepsy needs the occurrence of a minimum of one epileptic seizure [4]. this condition is the 4 th most common neurologic disorder affecting people of different ages [5]. there are about 65 million people affected all around the world, with a high and dramatic impact not only on the patient’s quality of life, but also on the professional development and social behavior; the health system budget is highly affected as well [6]. epilepsy may have an effect on people of any age but it is most widespread among children and the elderly. a few kinds of epilepsy are inherited and are caused by genetic factors. other probable epilepsy causes involve brain injuries because of oxygen deprivation at birth or head traumas. in several of the situations, the reason behind epilepsy is simply not known [7]. 3. seizure a seizure is an unusual behavior (with symptoms or signs) that results from unusual discharges of cortical neurons. this phenomenon, which is observable, is finite in time. epilepsy is a definition of a chronic state which is defined by repeated occurrences of seizures. a syndrome is a set of symptoms and signs occurring together, however, unlike disease, have no single known cause or pathology [8]. seizures occur, in the majority of the patients, suddenly with no external symptoms. the sudden occurrences of those seizure pose a serious concern and accounts for mortality in patients that have uncontrolled epilepsy. thus, timely predicting seizures provides a sufficient time for reducing risks of seizures and thereby improve the quality of life for the affected [9]. a seizure could seem to happen in a spontaneous way, with no external cause, even though in a great deal of patients a cause like a flashing light, redundant sounds or stressful cases are easily characterized as triggers of seizure. while seizures often happen during sleep, a seizure during the waking time could be a cause for the patient to harm themselves when they suddenly lose consciousness. the danger that this poses to the epileptic patient and others is obvious. they could fall and harm their head, fall into moving machinery or lose control of a car. 4. seizure types until the past few years, seizures were categorized based on the international classification of seizures, which has been suggested by the “international league against epilepsy (ilae) [10]. in 2017, ilae announced a new classification of seizures according to the onset of the seizure (i.e. focal or generalized), the state of consciousness at the time of seizure (complete or impaired awareness), and on the symptoms that occur at the time (motor or otherwise) [11]. • focal onset seizures (or partial seizures).this type of are more widespread than generalized seizures and happen in one or more certain locations in the brain. in some of the situations, they could spread to wider areas in the brain. they typically happen as a result of some injuries, but in the majority of the cases the specific origins are not known (idiopathic). • generalized onset seizures. this type usually occurs in each of the brain sides. those seizures are combined with loss of consciousness. many types of those seizures are genetically based. people typically have normal neurologic functions between episodes. • unknown onset seizures. in some of the cases, the seizure onset happens unobserved and it is difficult to determine if it started out as focal or generalized. 5. seizure detection using wearable biosensors in a clinical setting, electro-encephalo-graphy (eeg) in combination with video monitoring is the optimal standard for detecting and diagnosing different neuro-logical cases including epilepsy. the capability for the automatic detection of seizures is crucial for different diagnostic, safety, and treatment causes. for example, the diagnosis of a patient that has epilepsy needs capturing ictal episodes with the use multi-channel eeg. which could be time consuming and costly at the same time, and requires either a clinic stay or wearing ambulatory devices for a number of days [12]. with the continuous need from the patients to have a normal life while being observed for their physiological activities, wearable biomedical alla fikrat alwindawi al-khwarizmi engineering journal, vol. 16, no. 2, p.p. 113 (2020) 3 sensors are playing a significant part. to achieve this, new adhesive tape type wearable sensors enable sensor integrations [13]. there are several devices on the market which are designed for the detection of convulsive seizures with the use of extra-cerebral (non-eeg) signals. the majority of those devices use motion sensors due to the fact that convulsive movement is identical amongst patients, and therefore readily identifiable. on the other hand, there are no any wearable devices available for the detection of complicated partial seizures (cps), as they are non-convulsive [14]. designing and developing of wearable biosensor systems for monitoring health has captured a great deal of focus in the industry as well as in scientific association in the past few years. primarily motivated by the increase in health-care expenses and powered by recent improvements in the technology of miniature bio-sensing devices. such as wireless communications, smart textiles, and micro-electronics. the constant development concerning wearable sensor-based schemes will have a great potential in transforming the future of health-care by allowing ubiquitous monitoring of a patient's’ health and permitting proactive management for personal health. those systems may include different kinds of small physiologic sensors, transmission modules, and processing abilities, and therefore is capable of facilitating wearable low-cost unobtrusive results for constant day-round and anyplace health, also monitoring activity and mental status wearable-systems for the purpose of monitoring health could include different kinds of little sensors, implantable or wearable. those bio-sensors can measure important physiologic parameters such as hearts rate, oxygen saturation, blood pressure, the temperature of body and skin, rate of respiration, electrocardiogram, and others. the measurements that were gained are being communicated by a wired or wireless linked to the centralized node, for instance, a personal digital assistant that is abbreviated as (pda) or a micro-controller board that can afterward display the associated data on the user interface or transfers aggregated important signs to the health center. the previous depicts that a wearable system could include many different components such as: wireless communication modules and links, user interface, smart textiles, power supplies, sensors, wearable materials, software, control and processing units, decision-making algorithms and advanced data extraction [15]. in most countries in the middle east, epileptic patients are feared to be known by the community because of their stigma because of social stigmatization. therefore, it is necessary to find a way to detect cases of epilepsy before using modern technology [16]. 6. technologies review 6.1 researches based on ecg most of epilepsy patients severed a sudden unexpected death (sud) due to neurogenic cardiac arrhythmias, for that one study suggest using electrocardiograms (ecg) to monitor implantable loop recorder [17-18]. the method showed effective automatic detection of bradycardia and tachycardia. van elmpt et al. (2006) [19] held an investigation which developed an algorithm based on the analysis of heart rate pattern by using ecg. this method can determine the heart rate patterns for the automatic detection of seizures in epilepsy patients. malarvili et al. (2009) [20] applied a method that contains a sequence of processes to monitor the epilepsy patients and used a supervised statistical classifier for hrv classification. the suggested method showed the sensitivity of hrv to the changes in the cardio regulatory system of the heart, which helped detecting seizures in patients with epilepsy. recent development in miniaturizing ultra-low power elements offer more intelligent wearable health monitors. the evolvement and evaluation of a wireless wearable electrocardiogram (ecg) monitor for the detection of epileptic seizures from variations in the cardiac rhythm is described. the ecg data is analyzed with the use of embedded algorithms: a robust beat-detection algorithm in combination with a real-time epileptic seizure detector [21]. an investigation has been held to test the ability of algorithm based on electrocardiographic (ekg) based seizure detection [22]. the results of ekg obtained a good quality that reached (91%), which was acceptable and promising using these for further analysis. behbahani et al. (2016) [23] also developed an algorithm based on heart rate analysis (hrv) analysis by predicting when the seizures may occur according to dynamical variations of ecg during the pre-ictal period. the presented method showed a potential for monitoring epileptic patients and improving their life quality. the general efficiency of the algorithm is an important step for clinical implementations. alla fikrat alwindawi al-khwarizmi engineering journal, vol. 16, no. 2, p.p. 113 (2020) 4 the study of shamim et al. (2016) [24] showed that using electrocardiogram (ecg) is one of the best ways for detecting epilepsy seizures, because it is comparatively easier compared to eeg. the results showed that the proposed algorithm detected epileptic seizures efficiently and compared to other models, it has been found to be more effective. 6.2. researches based on acm whereas, nijsen et al. (2005) [25] used the visual analysis of 3-d accelerometer (acm) and video/eeg recordings to predict epilepsy. the study results showed good results, 91% of the seizure with motor phenomena have been detected by using recorded data with these sensors and considered feasible for detecting seizures. cuppens et al. (2009) [2] suggested another detection systems applied with accelerometers acm that are attached to wrists and ankles. this system used the development of an automatic detection algorithm. a detection system can solve the unsuitable use problem of eeg in the daily lives of patients, by using the development of an automatic detection algorithm. this resulted in an algorithm of sensitivity of up to 91.67% and accuracy of up to83.92%. another study used acm with a different algorithm based on a bayesian approach and found that the patient in standing up status promotes a good detection close to 90% of seizures and 25% of false alarms [26]. schulc et al. (2011) [27] used a wii remote (r) which encased an accumulator and bluetooth antenna and by using this device achieved 100% temporary sensitivity and specificity of over 88% while a positive predictive value ≥75% of false alarm ratio. another study used wireless acm sensor with some physiological parameters, the false alarms were reduced with realizing a high level of detection [28]. borujeny et al.(2013) [29] revealed the benefit of wireless sensor networks (wsn) in the application of health monitoring to detect epilepsy seizures. this application can be used in a clinical environment or at the patient’s home. they used acm in the portable device. this study obtained 85% sensitivity with 3fp, while another study got a high sensitivity of up to 90% and a low rate of false alarms (0.2/day) which used the same device with a different algorithm [30]. the study of gheryani et al. (2017) [31] examined the wireless body area network (wban) to detect and identify seizures by the armband via a portable unit. the study used an inertial measurement unit and muscular activity acquisition sensors and these signals were transmitted from the used device. helmy & helmy, (2015) [32] created the first mobile application which was called seizario, this app offered a set of useful properties that help to provide assistance to epilepsy patients. seizario app. are introduced a new accelerometerbased learning algorithms with elaborate finitestate-machines for the automatic detecting of grand mal seizures and harmful falls. seizario’s detecting algorithms were designed to operate efficiently on mobiles and showed great potential with more than 95% detection rate for each of seizures and falls, with a minimum number of false alarms. whilst ribeiro et al. (2016) [33] used the wearable device from acm and embedded sensors by applying machine learning algorithms obtained knn 99% and c4.5 & part 98% and there was no valuable variation at the results between knn, part, and c4.5… an experiment showed that the user of wearable accelerometer sensor was found very efficiently with a limited number of false alarms (tonpe et al., 2017) [34]. also kusmakar et al. (2017) [35] used wearable acm sensors and their results showed that the sensitivity was 23% with 0:72=24h. 6.3. researches based on mixed sensors (e.g. eda, acm, ecg, emg, spo2 video, audio skin, temperature and br) poh m . (2011) [36] proposed an approach to monitor sympathetic nervous system activity during epileptic seizures with the use of a wearable sensor measuring electro-dermal activity (eda) and acm. the sensitivity of the method reached 94% tonic-clonic seizures with low rate of false alarms (<;1 per 24h). another study used a method to distinguish between ordinary movement and hyper motor seizures [37]. the acm was applied in both wrist and ankle to get the dataset with synchronized video, audio, eeg, ecg, upper arm emg and acm data. the results were achieved 100% sensitivity and positive predictive values ppv which ranged from 34.91% to 100%. other researchers monitored the human health by observing some physiological signals such as electrocardiogram (ecg), respiration and electromyography (emg) signals. (altini et al., 2011) [38] promised to use these findings to alla fikrat alwindawi al-khwarizmi engineering journal, vol. 16, no. 2, p.p. 113 (2020) 5 monitor the epilepsy seizure. becq et al. (2011) [39] used motogrogram to detect different types of epilepsy seizures. by collecting data from triaxis accelerometers and magnetometers. conradsen et al. (2012) [30] applied an automatic multi-modal intelligent seizure acquisition (misa) system to detect motor seizures from electromyography data. their results showed that the misa system has highly sensitive short detection latency and a low rate of false detection. moreover, the results have shown that the multimodal detecting system is superior when compared with a uni-modal system. the proposed system has a potential to detect seizures according to multi-modal data. a group of researchers developed a small medallion which is attached to the patient's neck with the use of a necklace type grip that consists of combining the spectral analysis method of anomalous currents with modern processors and mobile communications technology such as gps and bluetooth [40]. the device disassembles and amplifies only the primary brain currents, the ones of epileptic seizures, and warns the patient of possible danger the voice warning is used to connect the mobile to the patient with the use of a specified program, and to send an emergency text that the seizure reports are imminent and the current location with the use of gps system for the emergency service, the doctor, and the national center for epilepsy monitoring and communication in advance. in the recent years, cloud computing in the area of health-care started gaining importance. pandey et al. (2012) [41] presented a model for on-line monitoring of the patient’s health with the use of cloud computing technology. also, internet of healthcare things (ioht) became very essential in field healthcare. abdulaziz a. albesher (2019) [42] provides an overview of different aspects of iot in healthcare. forkan et al. (2014) [43] presented a model which is based on a service-oriented model enabling real-time aided living services. it offers a flexible middle-ware layer hiding the complexity in managing sensor data from various types of sensors and contextual information as well. fortino et al. (2014) [44] presented a model which is based on combining the utilization of bsns and cloud computing. it performs monitoring of assisted living by wearable sensors which transmit data to the cloud using a mobile. a study presented a method which considered the first step in the direction of a reliable ambulatory monitoring system for epileptic seizures with or without motor activities (helderg et al., 2015) [45]. a hierarchical classification method has been implemented for the detection of various types of epileptic seizures utilizing data from wearable sensors (eda and acm). they obtained a general sensitivity of up to 89.1% and a general accuracy of up to 93.1% was obtained with motor activity by using a k-nearest neighbor (knn). whereas with no motor activity the sensitivity reached a percentage of 97.1% and the accuracy reached 92.9% single seizure detecting methods have the problem of high false positive rate cogan et al,.2015) [46]. a group of signals that may be easily monitored by a wrist -worn device have been found and which produced a distinctive pattern during the time of seizures for patients in epilepsy monitoring unit (emu) a group of five bio-signals have been chosen, which may be monitored at the wrist and are known or believed to be affected by seizures they are: heart rate (hr), arterial oxygenation (spo2), accelerometry (acc), electrodermal activity (eda) and temperature (temp). several researchers have notices great hr changes at the beginning of some kinds of seizures; they needed to collect more data from epileptic patients in a day by day basis, in addition to emu settings prior to being confident of having found a seizure detection method beneficial for a wide range of people. data collection is continuing, so we will have opportunity to further evaluate our findings. we expect that more sophisticated methodologies mentioned in subsection. sasikala et al. 2016 [47] proposed the design, development and validation of a wrist-based wearable device that can not only detect seizures efficiently, but over time can also predict a seizure before the actual onset. the results concluded that seizure detection would primarily involve the measurement of the following parameters: (i) motion , (ii) electro-dermal activity (eda), (iii) skin temperature, and (iv) heart rate. a new multi criteria decision system (mcds) was proposed by ahmed et al. (2017) [48], they obtained a precision of 96% with 90% recall over the synthetic data. in this study, they used the parameters of electro-cardiograph (ecg), electrodermal activity (eda), body motion and breathing rate (br). different physical factors were applied to transmit the signals of seizures to a cell phone device ramirez-alaminos et al. (2017) [49], these physical factors are temperature, heart rate, and extreme motion. the authors examined different temperature values, heartbeats and tested the battery life of the used system. alla fikrat alwindawi al-khwarizmi engineering journal, vol. 16, no. 2, p.p. 113 (2020) 6 audio identification was applied on a group of epilepsy patient in the netherlands (de bruijine at al., 2009) [50]. the used system was comprised of three stages; this system depended on a theory of bayesian to classify the characteristics vector. a proposal of a non-intrusive video analysis system for the patient’s body parts movement analysis in epilepsy monitoring unit is present by (mandal et al.2012) [51]. the system utilized skin colour modeling, head/face posture template matching and facial detection for the analysis and quantification of the head motions. epileptic patients’ heads have been analyzed in a holistic way for inferring seizures and usual arbitrary motions. the patient is not required to wear any specific clothes, markers or sensors, therefore it is entirely non-intrusive. saleh m. gaber et al. (2017) [52] depended on the eeg network on chip (noc) concept to display and predict unstable brain waves. this prevents the risks of seizure during the driving and childhood stage. table 1 provided a comprehensive summary of the state-of-the-art literature on epileptic seizure detection including the methods and algorithms used and the results obtained. table 1.1, the review of different method, algorithm and results for the detection of seizures. ecg= electrocardiography , eeg= electroencephalography , hrv=heart rate viability, acm= accelerometer , knn= k-near neighbors, eda= electro-dermal activity, emg= electromyography, spo2=arterial oxygenation , temp= temperature, noc=network on chip , far=false alarm rate , fdr= false discovery rate, fp= false positive, ppv= positive predictive value, sne= sensitivity, svdd=support vector data description , svdd=support vector data description, ppv= postivie predictive value , fdr= false detection rate , h= hours , avg= average, fpr= false no. article method algorithm results 1 rugg-gunn et al. (2004)[16] ecg device implantable loop recorders detected the beat per min of hr in seizure patients 2 nijsen et al. (2005)[25] acm & video/eeg visual inspection of the data 48% of seizures were detected by acm. 91% of the seizures with motor phenomena were detected 3 van elmpt et al. (2006)[19] ecg two algorithm were used: i. curve-fitting used to characterize the hr patterns. ii. a moving median filter to detect the change of hr more than 10seizures of 2 patients out of 3 showed a sensitivity 90% no. article method algorithm results 4 de bruijne et al. (2009)[50] audio signals bayesian decision theory the sensitivity 95 to 98% and specificity 72 to 97% , depending on sound type ppv 2-40% 5 malarvili et al. (2009)[20] ecg used the heart rate viability (hrv) to detect newborn seizures the sensitivity 85.7% and 84.6% specificity 6 cuppens et al. (2009)[2] acm development of an automatic detection algorithm sensitivity of 91.67% and a specificity of 83.92%. 7 poh m et al. (2010)[53] eda novel method for monitoring sympathetic nervous system 8 jallon (2010)[26] acm based on a bayesian approach using hidden markov models able to find out 90% of seizures when far are 25% of alarms. 9 poh, m. (2011)[36] acm & eda monitoring sympathetic nervous system activity the sensitivity of the method reached 94% tonic-clonic seizures with low rate of false alarms (<;1 per 24h). 10 van de vel et al. (2011)[37] acm work on algorithm for distinguishing between normal movement and hypermotor seizures the results were achieved 100% sensitivity and positive predictive values ppv ranged from 34.91% to 100%. alla fikrat alwindawi al-khwarizmi engineering journal, vol. 16, no. 2, p.p. 113 (2020) 7 11 schulc et al. (2011)[27] (acm)-based dives wii remote® achieved 100% temporary sensitivity and specificity of over 88% while a positive predictive value ≥75% of false alarm ratio. 12 becq et al. (2011)[39] acm & magnetometers artificial neural networks. sensitivity 90%, fdr per night 0.7 13 altini et al. (2011)[38] ecg , respiration and emg signals low-power, multi-modal, wearable sensor platform the author promised to use these finding to monitor the epilepsy seizure 14 conradsen et al. (2012)[30] emg , acm & gyro automatic multi-modal intelligent seizure acquisition (misa) sensitive short detection latency and low rate of false detection. a 100% sensitivity was observed with fdr per 0h and mean response 0.7s 15 mandal et al. (2012)[51] video the system utilized skin colour modeling, by using smv to classify the seizure and normal movement this method limited use in hospital to monitor the statues of the epilepsy patients 16 popescu et al. (2013)[40] small medallion which is attached to the patient's neck with the use of a necklace type grip method of spectral analysis of abnormal cerebral currents with modern microprocessors and mobile telecommunication technologies 17 conradsen et al. (2012)[30] acm high sensitivity of up to 90% and a low rate of false alarms (0.2/day) 18 borujeny et al. (2013)[29] acm artificial neural network and k nearest-neighbor sensitivity85%,3fp 19 massé et al. (2013)[21] ecg a robust beat-detection algorithm in combination with a real-time epileptic seizure detector the system obtained 75% of sensitivity and 70.4%specificity. 20 osorio et al. (2014)[22] ekg-based threshold ekg obtained a good quality that reached (91%) a total of 241 out of 266 clinical seizures. 21 salem et al. (2014)[28] acm we use the exponentially weighted moving average algorithm highly level detection accuracy in against temporal variation. 22 helmy et al. (2015)[32] acm seizario app depending on acm in smartphone more than 95% detection rate for each of seizures and falls, with a minimum number of false alarms no. article method algorithm results 23 helderg et al. (2015)[45] eda and acc a hierarchical classification method has been implemented, by using a k-nearest neighbor (knn) classified. obtained a general sensitivity with motor activity : up to 89.1% and a general accuracy of up to 93.1% was obtained .whereas with no-motor activity : the sensitivity reached 97.1% and the accuracy reached 92.9% 24 cogan et al. (2015)[14] temp, hr, acm, spo2 & eda versatile bio-signal activity recognition algorithm in which the physician received the seizure response time electronically observed the change in hr↑ ⇒ spo2 ↓ ⇒ eda↑ by special algorithm in six out of 10 patients 25 shamim et al. (2016)[24] ecg by setting threshold and by using linear support vector machine obtained accuracy 94.2%, sne 84.1% and specificity 94.5% alla fikrat alwindawi al-khwarizmi engineering journal, vol. 16, no. 2, p.p. 113 (2020) 8 6.4 commercial devices there are different technologies developed for tracking seizure information. the developed devices and mobile applications will becomes a tool to help patients, families, and clinicians capture seizure data. the table 1.2 shows the commercial device with their details. 26 behbahani et al. (2016)[23] ecg the algorithm based on heart rate analysis (hrv) analysis by prediction the occurrence of seizures based on dynamic changes of ecg result showed an avg sne of 78.59% and avg fpr of 0.21/h false prediction rate 27 sasikala et al. (2016)[47] acm ,eda, hr & skin temperature the paper proposes to design / 28 ribeiro et al. (2016)[33] acm and embedded sensors machine learning obtained knn 99% and c4.5 & part 98% and there was no valuable variation at the results between knn, part, and c4.5 29 kusmakar et al. (2017)[35] acm using machine learning approach kernelized support vector data description (svdd) results showed that the sensitivity 95:23% with 0:72=24h. 30 ahmed et al. (2017)[49] ecg , eda & br a multi criteria decision system (mcds) obtained a precision 96% with 90% recall over the synthetic data 31 gheryani et al. (2017)[31] acm, angular velocity (gyro) and emggyroscope approach starts with derivation of the root mean square for acm and gyro, followed by the normalization of whole signals in the same range and aggregation to a signal. the result showed 100% of sensitivity with 5% of far 32 mohammad saleh et al. (2017)[52] network on chip (noc) ecg the result present the eeg of noc chip depends on the design of network , wlan protocols , number of sensors and the packet size over the network 33 ramirezalaminos et al. (2017)[49] temp , hr and vibration sensor by using device has bluetooth module to connected wireless with smart phone depending on the parameter that used in the device give sign when it get over the threshold and its depended on the epilepsy type 34 onorati et al. (2017)[54] acm and eda used 3 different data of wristbands and test two new machine learning classifiers results of classifier(iii) showed that the sensitivity 94.55% and far 0.2 events/day 35 fürbass et al. (2017)[55] eeg ,ecg and emg automatic multimodal detection obtained 86% sensitivity with avg of false detection 12.8 in 24h 36 sopic et al. (2018)[56] ecg e-glass using 4 eeg electrodes the sensitivity 93.80% and 93.37% specificity 37 elger et al. (2018)[57] heart rate low complex novelty classifier detection results showed that sensitivity 77.6 % and avg of far 2.56 false alarms per night 38 geertsema et al. (2018)[58] video analyzing of oscillatory motion pattern and set threshold obtained 97% sensitivity with median of false alarms 0.78 per night alla fikrat alwindawi al-khwarizmi engineering journal, vol. 16, no. 2, p.p. 113 (2020) 9 table 1.2 review of different commercial devices commercial device used apparatus detection method website advance brain monitoring eeg with different no. of channels wireless eeg www.advancebrainmonitring.com emfit acm, bed motion sensor wireless transmission www.emfit.com affectiva wrist-band bio-sensor for measuring eda ,acm and body temp www.affectiva.com epdetect mobile application (base on acm of mobile) wireless transmission : sending sms ,movement detection and gps position location www.epdetect.com smart belt chest-belt ,wearable respiration sensor and eda sensor . movisens electrodes raw signal of eda , acm temp and air pressure www.movisens.com epi watcher acm , bed motion sensor wireless alarm bell, wired version integrated and message to responsible person www.vahlkamp.nl mio alpha streapless watch heart rate monitor www.alphaheartrate.com adlx330 wrist-band acm www.sparkfun.com pulseguard wrist-band heart rate changing www.pulseguard.org sensalert200 bed motion sensor detecting unusual movement www.sensorium.co.uk sami-sleep activity monitor video-camera night vision monitoring detecting unusual movement and send alarms and video records www.samialert.com baby-ping video-camera night vision monitoring with voice wi-fi connection www.babyping.com 7. discussion the epilepsy seizure detection and alert system is very important and urgent for saving the patient’s life. many social organizations encourage researchers to design such a system to make a penitent’s life more safer and prevent case of sudden unexpected death in epilepsy (sudep). this review paper gives a useful overview of the spectrum of non-eeg body signals which are related to seizures. the review shows that these body signals (such as electromyography (emg), heart rate (hr), oxygen level (spo2), accelerometer (acm) and eta) individually fail to detect seizures, so the effective seizure system is based on multi-body signals. in spite of if seizure alerts happen or not, these systems enhances the patient monitoring process by collecting the statistical date about the number of seizures during the period of time and the time between seizures. this information is very important for the diagnosti purpose. finally, the paper gives an up to date list of some available seizures detection commercial devices. 8. references [1] kurada, a., srinivasan, t., hammond, s., ulate-campos, a. and bidwell, j., 2019. seizure detection devices for use in antiseizure medication clinical trials: a systematic review. seizure, 66, pp.61-69. 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[57] e. e. geertsema, r. d. thijs, t. gutter, b. vledder, j. b. arends, f. s. leijten, g. h. visser, and s. n. kalitzin, “automated video-based detection of nocturnal convulsive seizures in a residential care setting,” epilepsia, vol. 59, pp. 53–60, 2018. )2020( 113، ! �� 2ا���د، 16���� ا�� ارز�� ا������� ا����� ا� ��اوي ���ت ا�ء 13 ا�.�ع �� )(ت �,ر+�اء ا�*()�� ا��'& أ�$�� ا�#��اض أ��� 2�34 ��اد*** 1.�(ن � ري** ا� ��اوي* أ�ء ���ت a13fg/ ا4?6<;ل/ اa>61d8س ab@>0/ ا8?<1>01 وا8>2;م ا045678 0123 *،** *uvw ھ0456 اa@;2<s8ت واqargqت/ 0123 ا045678 اo8;ارز@5ij 0<@ab /lاد :lxوfdy8q5 اzf>8ا*alla.alwindawi92@gmail.com :lxوfdy8q5 اzf>8ا**osman.usan@altinbas.edu.tr lxوfdy8q5 اzf>8ا*** :ameer@kecbu.uobagdad.edu.iq ا��,!� اfr8ع aj;xت aqxم ospdz. اqa`8ت lm n<j اam;8ة إiz j8دي وfg 5w;ا5d leوث aos8aj b>vjطf @`_;ف x^j[ اfr8ع f<z 0j;xف .اfj nzfs8أس eeg أa?wب رvgw@ 0>v68aj nzfs28 ، x1d udz sj أ@f وھ; ، (eeg) اa@58غ 5od4aj ;z51m /s1?ogام fs28اw<0 ا512rd8ي o@ورة وfp85ة اgav@ nzfs86<71[ اgو z>w 5وثd 0j;68ا l5 وھdت أ{yfs8ا ld82_| اz هa>dxا o1~da>8ا o1ssrs8وا .fm;dz �1وا�4 ط o@ 0sqxأ �fy8ا og تaj;6808 ا;s`s80 اdads8ا lm ا�4;اق ld856 واdvg lm a7s1srg j8رات إaإ� f1� رةaإ� eeg. og اa7b �fy8ز a�@ u1srgل lm اo@ azapr8 اl?ig 5z5<8 اld8 ا��f1ة اqars8ت f<d4qاض دراf1m;g 04 ھ; ا08ars8 ھ�ه @o ا578ف 0j;x lm |w;8ا lr1r`808 ا;s`s8ا z~@ راتaإ� uv�8ا ld8ا oysz a74a1w ، b18a4ارز@01 وأ;o8م ، اaqxو �f3 51b حad@ ًazرa�g. 0�1dx �8� 56dvg واld8 ار5gاؤھaj;x oysz aت اafd3ف أl?ig 0sqx اld8 ا8<`~01 اqars8ت @o ا5z5<8 ھa6ك أن ا�f<d4اض g 012sg;ض� ، 8 j8رات إaإ� uv�8ا .f~30 أsqx0 أ>wاfs8ف اafd3q018 واa<m lم ھaq68ي ا� .اzf@ ، 0p_o6@ 0wa?8`0 ، ا�avbم @d>5دة إ�aرات 5odvzم ا8 <4d6963726f736f667420576f7264202d20c7e6d1e5c7e420c7e1e4d3cec920c7e1e3d6cfc931312d3231> al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 16, no. 3, sptember, (2020) p. p. 11-21 prediction of creep-fatigue interaction damage for polyamide 6,6 composites orhan s. abdullah* shaker s. hassan** ahmed n. al-khazraji *** *,**,*** department of mechanical engineering / university of technology orhan_sabah@yahoo.comemail: * **email: shaker_sakran1952_1@yahoo.com ***email: dr_ahmed53@yahoo.com )received 26 february 2020; accepted 22 june 2020( https://doi.org/10.22153/kej.2020.06.001 abstract this paper aims to study the damage generated due to creep-fatigue interaction behaviors in solid polyamide 6,6 and its composites that include 1%wt of carbon nanotubes or 30% wt short carbon fiber prepared by an injection technique. the investigation also includes studying the influence of applied temperatures higher than the glass transition temperatures on mechanical properties. the obtained results showed that the addition of reinforcement materials increased all the mechanical properties, while the increase in test temperature reduced all mechanical properties, especially for polyamide 6,6. the creep-fatigue interaction resistance also improved due to the addition of reinforcement materials by increasing the theoretical damage value by 50% approximately, and the failure always happened through the rotating part of the creep-fatigue interaction test program. using the manson-halford damage equation to estimate the damage generated in polyamide 6,6 and its composites gives unsafe design conditions. keywords: cnts, creep-fatigue interaction, polyamide 6,6, short carbon fiber. 1. introduction thermoplastic polymers and their composites take a considerable place in the indusial field as a result of their good chemical stability, high damage and impact resistance, low processing costs, and their good performance at elevated temperatures [1]. all these characteristics motivate to suggest thermoplastic composites to be used in automobile industry, especially in manufacturing gears, bearings, clutches, etc. all these parts will be exposed to cyclic loading and high temperatures that may be higher than their glass transition temperatures (tg) [2, 3]. the failures of the engineering parts which are manufactured from polymers or polymer composites that operating at an elevated temperature and cyclic loading is caused by a complex phenomenon which is known as creepfatigue interaction, the combination of creep and fatigue effects leads to cause an accelerated failure at a time lower than that required for each creep or fatigue failure separately [4]. creep damage, is classified as a time-temperature dependent process, which depends mainly on the values of the stress and temperature that are applied to the test specimen. in contrast, fatigue damage will occur due to cyclic loading and is basically dependent on time; therefore, it is classified as a time-dependent process. as the two kinds of damages are collected on the operating part, creep-fatigue interaction damage was inevitably developed [5]. several authors investigated the creep-fatigue interaction behavior in metals, but a few researches are available about this interaction in polymers and their composites [4-10]. daniel d. samborsky et.al [6] studied the influence of the orhan s. abdullah al-khwarizmi engineering journal, vol. 16, no. 3, p.p. 1121 (2020) 12 addition of unidirectional glass fibers with 20 % wt on combined creep-fatigue behavior of biaxial woven glass fiber/epoxy composites with different test frequencies. the tests were performed at a temperature higher than tg, and the tensioncompression loading with stress ratios is equal to 0.1,-1, and 10. the results showed that the increase in test frequency reduced the time required to failure, while the addition of unidirectional glass fibers to the prepared composite improved their total time to failure. mahir h. majeed [7] predicted the creep-fatigue interaction damage in epoxy 135 reinforced with woven carbon fiber, according to damage energy and hysteresis loop energy values at 50°c, as well as suggesting a new method to estimate the material life by considering the relationship between damage energy and the crack area. b. vieille et.al [8] investigated the creep-fatigue interaction behavior in laminated polyphenylene/carbon fiber composite at a temperature higher than tg. three different types of loads were used to create a creep-fatigue interaction effect on the test specimen. the results showed that the increase in holding time holds the test specimens at stresses higher than the threshold value causes a plastic deformation, as well as, prior the fatigue loading by creep holding results an accelerated fracture. m. eftekhari and a. fatemi [9] assessed the influence of temperature, frequency, load level, and holding stress on the creep-fatigue interaction and thermal mechanical fatigue (tmf) behavior for different polymer composites, namely: polyamide 6,6 with 30 %wt of glass fiber, polypropylene with 30 % wt glass fiber, blend polypropyleneether & polystyrene with 20% wt of glass fiber, and polypropylene reinforced with 40% wt of talc particles at a range of temperatures varied between 85 and120°c. the results indicated a non-linear behavior in creep-fatigue interaction and tmf behaviors for all polymer composites, and the use of chaboche model gives an expected life estimation. abdolavahid movahedi rad et.al [10] developed a new creep-fatigue interaction model for polymer matrix composites which depends on lots of experimental fatigue data obtained from previous reviews. this new model can be used to obtain the fatigue behavior of different polymer composites when a small amount of data was available, as well as estimate the creep-fatigue interaction behavior by considering the thermal effect on fatigue behavior. yong guo et.al [11] assessed the low cycle fatigue-creep interaction phenomena in selftapping screws made of high-density polyethylene /rice husk powder composite at stress levels equal to 40, 60, and 80% of its tensile strength. the results showed that the decrease in holding time increases the fatigue damage effect and verse versa. a. vahid movahedi rad et.al [12] investigated the creep-fatigue interaction behavior of laminated glass fiber epoxy composite at different stresses and holding time levels. the obtained results indicate that a short holding time has a limited interaction effect while a clear reduction in creep-fatigue interaction resistance appeared with an increase in holding time, and the failure almost happened due to fiber pull-out or matrix crazing. in the present work, a comprehensive investigation of creep-fatigue interaction behavior for solid polyamide 6,6 reinforced with 1%wt cnts or 30%wt short carbon fiber will be employed at a range of stresses that varies between 70% and 90% of their yield stresses at temperatures higher than their tg value that are equal to 50°c according to dsc test that was performed for the prepared materials. 2. theoretical consideration 2.1 creep-fatigue interaction the overall damage generated by combined creep and fatigue effects is completely different from separated damage generated by each loading type alone. therefore, the influence of the creepfatigue interaction phenomenon on thermoplastic composites is more harmful in comparison to creep and fatigue effects separately and must be considered as a design parameter; also taking into account that the duration of the holding time may create additional physical effects by the interaction of the of tested material with the environment. to compute the damage generated due to creep-fatigue interaction effects, linear damage roles are suggested by manson and halford [13] that collect the damage term of creep and fatigue together and will be considered in this work as: d = ∑df + ∑dc = 1 …(1) where df and dc are fatigue damage and creep damage respectively. fatigue damage can be calculated according to miner's role for fatigue life evaluation as [14]: df = ∑ �� ��� …(2) where nf represents the experienced cycles while, nff refers to the number of cycles until failure at the selected stress and temperature. orhan s. abdullah al-khwarizmi engineering journal, vol. 16, no. 3, p.p. 1121 (2020) 13 the creep damage term can be calculated according to robinson's equation as [15]: dc = ∑ �� �� …(3) where th represents the holding time in hours, while the tr is the required time to creep rupture in hours at the selected stress and temperature. by substituting equations (2) and (3) in equation (1), the overall damage due to creep-fatigue interaction effect can be calculated according to equation (4): d = ∑ �� ��� + ∑ �� �� … (4) as the creep-fatigue interaction program is continuously repeated until failure, two counters for each parameter must be considered. x was used as a counter for fatigue damage while y was used for creep damage. therefore, the experimental damage based on equation (4) will be: d = � . x + �� �� . y …(5) the time spent in rotating up to the failure under fatigue loading can be calculated according to equations (6) and (7) as follows: � �� �� �� � � …(6) � ��� ��� �� � � …(7) by substituting equations (6) and (7) in equation (5), the damage equation will be: d = � � . x + �� �� . y …(8) thus, the theoretical total time until failure can be obtained as follows: tcf .the = tf .x + th .y …(9) in the present work, the failure always happened when the test specimens passed through the fatigue region in the creep-fatigue interaction program, therefore; y � x � y � 1 …(10) in order to obtain a safe design, it should be assumed that the number of repeats in the fatigue region equals the number of repeats in the creep region (x=y) in the creep-fatigue interaction test program. according to this assumption, the theoretical time until failure that is obtained will be lower than the actual value and gives safety in design. by substituting x=y in equations (8) and (9), the theoretical damage value and theoretical time until failure will be calculated as follows: dthe = y. [ �� ��� + �� �� ] …(11) tcf .the = y. [tf . + th] …(12) the ratio of n�/n�� will be 0.2, while the ratio of t#/t$ will be equal to 0.1. by substituting in equation (11), y will be equal to: y % &'�( ).* …(13) and the theoretical time until failure due to creep–fatigue interaction behavior can be calculated by substituting equation (13) in equation (12) as follows: t+�.�#, % &.-� .��/ ).* …(14) 3. experimental details 3.1 materials solid and reinforced polyamide 6,6 with 1% wt cnts or 30% wt, short carbon fibers as reinforcement materials are received from guangzhou engineering plastic industries (group) co., ltd., are tested on this work. 3.2 composite preparation solid polyamide 6,6 and its composites are prepared by an injection technique by guangzhou engineering plastic industries (group) co., ltd. the materials that are used as a reinforced material are cnts with (purity :> 95%, diameter: 20-25 nm, length: 25-40 µm) and short carbon fiber with (diameter: 10 µm, and average length 260 µm). 3.3. experimental test 3.3.1 tensile test a tensile test was employed at room and elevated temperatures for solid and reinforced polyamide 6,6 rod test specimens with 6 mm diameters as illustrated in figure (1) prepared according to astm d638 tensile test standard [16]. fig. 1. standard tensile test specimen. orhan s. abdullah al-khwarizmi engineering journal, vol. 16, no. 3, p.p. 1121 (2020) 14 3.3.2 creep-rupture test in order to estimate rupture time (tr) under creep influence, the creep-rupture test was performed at temperatures higher than tg and applied stresses varied between 70% and 90% of yield stresses for the prepared materials according to astm d 2990 creep test standard as illustrated in figure (2) [17]. fig. 2. standard creep-rupture test specimen. 3.3.3 fatigue and creep-fatigue interaction tests to predict the fatigue and creep-fatigue interaction behaviors for polyamide 6,6 and its composites at series of applied temperatures above and below their tg, a fatigue test machine equipped with a suitable furnace was manufactured for this purpose as shown in figure (3). the test specimens for both cases were prepared according to astm e606 rotating bending fatigue test standard as shown in figure (4 a & b)[18]. fig. 3. fatigue and creepfatigue interaction test machine. fig. 4-a. fatigue and creep-fatigue interaction test specimens. fig. 4-b. standard fatigue and creep-fatigue interaction test specimen. indeed, the creep-fatigue interaction test was based on some assumptions to generate a general equation suitable to estimate the creep-fatigue interaction behavior in polyamide 6,6 and its composites. k. noda et.al [19] indicated that when analyzing the specimen surface of polyamide 6,6 reinforced by short glass fiber with sem analyzer after subjected to approximately 20% of its required number of cycles to failure and testing temperature higher than the glass transition temperature that a high local stress intensity was created at the fiber ends due to microvoids generating at this zone which caused to crack initiate. on the other hand, as seen in the creep-rupture test performed in this work; the second creep stage in polyamide 6,6 and its composites were started at times nearly equal to one-tenth of its rupture time. based on these detections, the creep-fatigue interaction test program will be designed to rotate the test specimen for 20% of its number of cycles until failure under thermal fatigue test at the same level of applied stress and temperature, and then hold it under pure creep influence for a time equal to 10% of its time until rupture, and then the process will be repeated until the failure has happened. orhan s. abdullah al-khwarizmi engineering journal, vol. 16, no. 3, p.p. 1121 (2020) 15 4. results and discussion 4.4.1 tensile test results table (1) manifests the mechanical properties for solid and reinforced polyamide 6,6 at room and elevated temperatures. it can be recognized that the addition of reinforced materials improved the mechanical properties clearly, while the increase in testing temperature leads to the reduction of these properties, especially for polyamide 6,6. the addition of cnts particles leads to a good improvement in σy, σu, and the modulus of elasticity values at room temperature by 53%, 52%, and 138% respectively. within the continuous increase in testing temperature, the presence of cnts in polyamide 6,6 structures played an important role in preserving the mechanical properties at an accepted level, which increased the yield stress, tensile strength, and modulus of elasticity by 88%, 88%, and 100%, respectively in comparison to solid polyamide 6,6 at 130 °c. in contrast, the addition of short carbon fibers with 30% wt raised the enhancement in σy, σu, and the modulus of elasticity values at room temperature to 116%, 112%, and 276%, respectively. this improvement in mechanical properties can be attributed to the good wettability between the fibers and the matrix, and that results a high structural polyamide 6,6 composite has the ability to serve under high tensile loading conditions. in spite of the increase in testing temperature, the improvement in mechanical properties due to the increase in short carbon fibers addition gradually increased; it increased the yield stress, tensile strength, and the modulus of elasticity by 172%, 175%, and 324% respectively in comparison to solid polyamide 6,6 at 130 °c. table 1, polyamide 6,6 and its composites mechanical properties. material temp. °c σy (mpa) σu (mpa) e (gpa) pa6,6 20 56.37 83.15 3.117 60 39.66 57.82 2.131 70 36.00 52.54 1.926 80 32.32 46.88 1.7 pa6,6+ 1%cnts 20 86.62 126.41 7.42 60 63.40 92.25 5.47 70 57.33 83.73 4.9 80 53.00 77.41 4.4 pa6,6+ 30%cf 20 121.9 176.38 11.73 60 94.53 136.27 8.8 70 88.23 127.18 8.1 80 81.30 117.21 7.38 4.4.2 creep-rupture test results one of the most important parameters obtained from the creep-rupture test was the time to rupture (tr), due to its importance in the estimation of creep-fatigue interaction damage values. table (2) listed the time to rupture of all tested materials, and it can be seen that reinforced polyamides 6,6 have a longer time to rupture than solid polyamide 6,6, as well as that the increase in applied stress and temperature decreases the time to rupture values for all cases. this behavior was attributed to the fact that any increase in applied temperature higher than the tg will increase the mobility of molecular chains, and finally results in a high deformation level, while with the presence of reinforcement materials, the molecular chains were restricted and the composite showed a high resistance against deformation. high compatibility in creep behavior of pa6,6 composites were obtained in this work with creep behavior indicated by yu jia et al. [20] and yi luen li et al. [21] due to the addition of mwcnts to the polypropylene and epoxy resins, respectively. table 2, the time to rupture values for solid and reinforced polyamide 6,6. material σ/σy time to rupture tr (hr.) 60°c 70°c 80°c pa6,6 0.70 62.13 57.35 48.12 0.75 48.42 44.32 39.76 0.80 38.53 35.37 31.48 0.85 30.61 28.22 25.23 0.90 26.54 22.54 18.89 pa6,6+ 1%cnts 0.70 86.43 77.34 63.66 0.75 71.52 62.72 50.32 0.80 53.92 47.31 37.44 0.85 43.31 36.16 30.11 0.90 33.22 28.71 22.18 pa6,6+ 30%cf 0.70 97.43 86.28 77.12 0.75 80.32 71.42 61.33 0.80 65.35 56.43 46.26 0.85 53.66 44.82 34.87 0.90 41.57 33.78 26.24 4.4.3 fatigue test results pure fatigue and isothermal fatigue tests are employed with fully reversed loading (r=-1) for the prepared materials in order to achieve the number of cycles until its failure at each applied stress and temperature level. it is shown in figures (5, 6, and 7) that the increase in applied stress and temperature reduces fatigue life while the addition of cnts and short carbon fibers enhances fatigue orhan s. abdullah al-khwarizmi engineering journal, vol. 16, no. 3, p.p. 1121 (2020) 16 life broadly. the reinforcement materials played an important role in the inherent fatigue resistance in polyamide 6,6, by preventing the microcracks that initiated owing to cyclic loading from propagation as possible, the initiated microcracks were united with each other to create one main crack, which causes the failure. in solid polyamide 6,6, a number of microcracks were initiated and propagated without a deterrent in the loading direction, which caused a crazing failure mechanism. in contrast, with environmental temperature increases, the probability of chain scission increases too, due to the internal heat generation, and the weak heat dissipation to the surrounding polymers leads to accelerate the fatigue failure. with the presence of reinforcement materials, the molecular chains were restricted, and their mobility was limited and the failure required a long time to happen. fig. 5. the s-n curves for polyamide 6,6 at several temperatures. fig. 6. the s-n curves for polyamide 6,6 + 1%cnts at several temperatures. fig. 7. the s-n curves for polyamide 6,6 + 30%cf at several temperatures. 4.4.4 creep-fatigue interaction results tables (3, 4, and 5) reported the creep-fatigue interaction damage for polyamide 6,6 and its composites. it can be noticed that the values of x and y are equal to two for polyamide 6,6 while it equals to three for pa66/cnt and pa66/cf composites, this variation in x and y values can explain the influence of reinforcement materials on creep-fatigue interaction resistance. the test program was always started by fatigue cycling which caused a crack initiation due to rotating the test specimen for nf cycles and then followed by a period of holding time at certain temperatures caused a crack propagation as illustrated in figure (8), for polyamide 6,6, the second block in test program accelerated the crack propagation, and within the start of the rotating part in block three, the failure has happened. fig. 8. the creep-fatigue interaction test program orhan s. abdullah al-khwarizmi engineering journal, vol. 16, no. 3, p.p. 1121 (2020) 17 the failure mechanism in polyamide 6,6 can be summarized as a chain scission that occurs due to localized heat at a crack tip generated by cyclic loading leads to accelerate crack propagation and failure. on the other hand, polyamide 6,6 composites, after rotating and holding the test specimen for a period of time as considered in first block of test program, microvoids were generated in the interface region between the matrix and reinforcement materials. in spite of continuity in applied cyclic loading and holding the test specimen for a period of time under creep influence for two additional block programs, the failure has not happened. this can be explained that the reinforcement materials prevent the accelerated failure by preventing microcracks that initiated near the fiber sides or grain boundaries of nano particles from propagation as possible, but the nucleation of new microcracks was continuous. with an increase in microcracks in the interface region, a debonding phenomenon occurs along the fiber side or nano grain boundaries leads to create cracked walls by connecting the microcracks together, which weakens the composite material, and then finally fractures it with ductile manner under cyclic loading in the fourth block of creep-fatigue interaction program. furthermore, from obtained results, it can be observed that the increase in stress amplitude and temperature accelerated the failure by reducing the time required until its fracture. it can be seen that the experimental damage values for all cases are less than one; these results are not compatible to the manson halford rule which assumed the total damage for creep-fatigue interaction should be equal to one, as well as the total number of cycles until the failure under creep-fatigue interaction behavior is lower than the required numbers of cycles until failure under only fatigue effect and the total time until failure due to interaction was also lower than the rupture time due to only creep influence. table 3, summary of creep-fatigue interaction damage for polyamide 6,6. temp. °c σ/σy nf (cycle) nff (cycle) x df th tr y dc dtotal 60 0.70 12766 63830 2.12 0.424 6.213 62.13 2 0.2 0.624 0.75 9112 45560 2.14 0.428 4.842 48.42 2 0.2 0.628 0.80 5965 29825 2.08 0.416 3.852 38.52 2 0.2 0.616 0.85 3844 19220 2.11 0.422 3.061 30.61 2 0.2 0.622 0.90 1689 8445 2.09 0.418 2.654 26.54 2 0.2 0.618 70 0.70 10238 51190 2.14 0.428 5.735 57.35 2 0.2 0.628 0.75 7450 37250 2.02 0.404 4.432 44.32 2 0.2 0.604 0.80 5102 25510 2.18 0.436 3.537 35.37 2 0.2 0.636 0.85 3157 15785 2.02 0.422 2.822 28.22 2 0.2 0.622 0.90 1390 6950 2.07 0.414 2.254 22.54 2 0.2 0.614 80 0.70 8258 41290 2.08 0.416 4.812 48.12 2 0.2 0.616 0.75 6079 30395 2.14 0.428 3.976 39.76 2 0.2 0.628 0.80 3988 19940 2.09 0.418 3.148 31.48 2 0.2 0.618 0.85 2572 12860 2.11 0.422 2.523 25.23 2 0.2 0.622 0.90 1126 5630 2.03 0.406 1.889 18.89 2 0.2 0.606 *where x: the total rotating cycles/ nf , and y: the total holding time/ th. orhan s. abdullah al-khwarizmi engineering journal, vol. 16, no. 3, p.p. 1121 (2020) 18 table 4, summary of creep-fatigue interaction damage for polyamide 6,6 + 1% cnts. temp. °c σ/σy nf (cycle) nff (cycle) x df th tr y dc dtotal 60 0.70 23990 119950 3.04 0.608 8.643 86.43 3 0.3 0.908 0.75 17413 87065 3.16 0.632 7.152 71.52 3 0.3 0.932 0.80 12608 63040 3.12 0.624 5.392 53.92 3 0.3 0.924 0.85 8132 40660 3.11 0.622 4.331 43.31 3 0.3 0.922 0.90 3625 18125 3.34 0.668 3.322 33.22 3 0.3 0.968 70 0.70 20208 101040 3.17 0.633 7.734 77.34 3 0.3 0.933 0.75 14604 73020 3.21 0.642 6.272 62.72 3 0.3 0.942 0.80 11518 35035 3.11 0.675 4.731 47.31 3 0.3 0.975 0.85 6866 34330 3.09 0.618 3.616 36.16 3 0.3 0.918 0.90 3053 15265 3.11 0.621 2.871 28.71 3 0.3 0.921 80 0.70 17174 85870 3.12 0.621 6.366 63.66 3 0.3 0.921 0.75 12402 62010 3.19 0.638 5.032 50.32 3 0.3 0.938 0.80 9007 45035 3.14 0.628 3.744 37.44 3 0.3 0.928 0.85 5770 28850 3.09 0.618 3.011 30.11 3 0.3 0.918 0.90 2576 12880 3.11 0.622 2.218 22.18 3 0.3 0.922 *where x: the total rotating cycles/ nf , and y: the total holding time/ th. table 5. summary of creep-fatigue interaction damage for polyamide 6,6 + 30% cf. temp. °c σ/σy nf (cycle) nff (cycle) x df th tr y dc dtotal 60 0.70 31684 158420 3.42 0.684 9.743 97.43 3 0.3 0.984 0.75 20422 102110 3.38 0.676 8.032 80.32 3 0.3 0.976 0.80 13475 67375 3.41 0.682 6.535 65.35 3 0.3 0.982 0.85 9525 47630 3.34 0.668 5.366 53.66 3 0.3 0.968 0.90 4070 20350 3.43 0.686 4.157 41.57 3 0.3 0.986 70 0.70 27440 137200 3.47 0.694 8.628 86.28 3 0.3 0.994 0.75 17768 88440 3.45 0.693 7.142 71.42 3 0.3 0.993 0.80 11892 59460 3.38 0.676 5.643 56.43 3 0.3 0.976 0.85 8373 41865 3.40 0.680 4.482 44.82 3 0.3 0.980 0.90 3568 17840 3.43 0.686 3.378 33.78 3 0.3 0.986 80 0.70 21498 107490 3.45 0.690 7.712 77.12 3 0.3 0.990 0.75 13786 68930 3.44 0.688 6.133 61.33 3 0.3 0.988 0.80 9814 49070 3.38 0.676 4.626 46.26 3 0.3 0.976 0.85 6648 33240 3.41 0.682 3.487 34.87 3 0.3 0.982 0.90 2884 14420 3.39 0.678 2.624 26.24 3 0.3 0.978 *where x: the total rotating cycles/ nf , and y: the total holding time/ th. in fact, the theoretical damage values that were obtained according to equation (11) have a high compatibility with experimental damage values that are listed in tables (3, 4, and 5), and in order to obtain a safety design under creep-fatigue interaction behavior for polyamide 6,6 and its composites, the values of dthe should be lower than the experimental values and should be limited within the following ranges: for polyamide 6,6: 0 � 1 � 0.6 for reinforced polyamide 6,6: 0 � 1 � 0.9 orhan s. abdullah al-khwarizmi engineering journal, vol. 16, no. 3, p.p. 1121 (2020) 19 the experimental results of the damage value vary between 0.604 and 0.636 with an average value equal to 0.62 for solid polyamide 6,6, while it varied between (0.904 -0.975) and (0.9680.994) with average values of 0.931 and 0.98 for polyamide 6,6 +1% cnts and polyamide 6,6 +30% cf respectively. all experimental damage values are higher than the theoretical damage values, and this indicates that the initial assumption that is considered for creep-fatigue interaction behavior gives a safety design. finally, according to the obtained theoretical damage values dthe, a general amplitude interaction diagram can be plotted for polyamide 6,6 and its composites which is suitable for safety design under the influence of creep-fatigue interaction within a range of temperatures that varies between room temperature and 80 °c since there was no variation in experimental damage values that was seen with temperature change. figures (9 and 10) illustrated the general amplitude interaction diagrams for polyamide 6,6 and its composites. it can be seen clearly that the addition of carbon fibers or carbon nanotubes increases the safe design zone under the influence of creep-fatigue interaction conditions by 50%. a high agreement in general amplitude interaction diagrams was achieved in this work that was obtained by j. bowman and b. barker [22] when investigated the methodology for describing the creep-fatigue interaction damage in polymers and their similarity to metal. fig. 9. the general amplitude interaction diagrams for polyamide 6,6. fig. 10. the general amplitude interaction diagrams for both polyamide 6,6 composites. 5. conclusions according to the results above, the following can be concluded: 1. the addition of cnts and short carbon fibers to polyamide 6,6 improved their tensile strength, modulus of elasticity, yield stress, creep rupture time, and fatigue life. 2. the increase in test temperature reduced all the mechanical properties and accelerated the failure. 3. in all creep-fatigue interaction test specimens, the failure always happened during the rotating part in the test program. 4. the 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[22] j. bowman and b. barker, ‘a methodology for describing creep-fatigue interactions in thermoplastic components’, polymer engineering and science, vol. 26, no. 22, pp.1582-1590, 1986. )2020( 1121، ! � 3، ا���د����16 ا���ارز�� ا������� ا����� اورھ�ن ��ح ��� هللا 21 ٦,٦ا����� أ���5 ��2.ا��4تا�1��2 ��0/.ر ا���+�, +�ا*( ا�)'& �% ا�$#ل أ'�� >�5& ا��)ر;�*** :�4. �$.ان '9,** *أورھ�ن ��ح ���هللا ����� /ا������ ا����������*،**،***���� $#" ا�!� �� ا� :&� orhan_sabah@yahoo.com*ا�+)* ا(���)و :&� shaker_sakran1952_1@yahoo.com**ا�+)* ا(���)و dr_ahmed53@yahoo.com: ا(���)و�& ا�+)* *** ��ح أورھ�نم.م. � #� ا� و��)اk+�4!--� ا��--& 4>�--�ي 1i--: ا��h--�g ا��--�ر�gن ٦,٦ا��--dل ��--�دة ا�+--��& أ��*- �--@ *! ف ھ=ا ا�+>; ا�: درا�� ا�8)ر ا���64 �5 4 ا23 ��1ك ا�/.--, ا� را�--� 84--�5 ا*8--�" ا��>u--m �--5 % ا��>8--)ة m*(sg--� ا�5m<��--g �--+��m. ٣٠و ا��--�ف ا��--�ر�gن ا�pm--�)ة �g#--) وز�--& أ% ١ا�����*--� �g#--) وز�--& �m-اره 1��اد ا��>8)ة �i در��ت .)ار� ���������ا�/�--��&. أظ!--)ت ا���--�\6 ا��#�>p--�1 أن أ]--��z �--�اد ا��-�i" $- 4>��!--�ا1i: �5 در�� .)ارة *�ا��yاص ا� �--�دة ا�+--��&� "�^�p3و �������������� و��5 ا�/*�دة z& در��ت ا�>)ارة ا���s1# أدت ا�: 3`_ ���@ ا��yاص ا����� ٦,٦أ��*- .#�a �5 $�" ا��yاص ا� ��. وb�=k أن ا]��z ��اد ا�i � (�cو�� ا��m� 5� a�#. $ "�i � لdار 4 ا23 ا�/., �@ ا�� m�g ي(dا�8)ر ا�� ��وان .��--� ا�`m4 % 2--f)*+�، g٥٠/*�دة $� ag . لd3 ���--�د $--���ن دا\�iل وأن اd--م ا�3+--�ر 4-ا23 ا�/.--, �--@ ا���--d��--�5 ا�8--)ر ��--�دة ا�+--��& manson-halfordا��/ء ا��yص d���gل �--5 y�� � ٦,٦أ��* �+kو��)ا �!&s�* ."��pاض ا��(kl أ��� (�k 6\��� dr. sattar j. habeeb/al-khwarizmi engineering journal, vol.3, no. 2 pp 17-31 (2007) 17 al-khwarizmi engineering journal al-khwarizmi engineering journal, vol.3, no.2, pp ١٧-٣١ (2007) investigation of heat transfer phenomena and flow behavior around electronic chip dr. sattar j. habeeb mechanical engineering dept. technology university (received 1 november 2006; accepted 24 april 2007) abstract: computational study of three-dimensional laminar and turbulent flows around electronic chip (heat source) located on a printed circuit board are presented. computational field involves the solution of elliptic partial differential equations for conservation of mass, momentum, energy, turbulent energy, and its dissipation rate in finite volume form. the k-ε turbulent model was used with the wall function concept near the walls to treat of turbulence effects. the simple algorithm was selected in this work. the chip is cooled by an external flow of air. the goals of this investigation are to investigate the heat transfer phenomena of electronic chip located in enclosure and how we arrive to optimum level for cooling of this chip. these parameters, which will help enhance thermal performance of electronic chip and flow patterns, through the understanding of different factors on flow patterns. the results show the relation between the temperature rise, heat transfer parameters (nu, ra) with (ar, q) for two cases of laminar and turbulent flows. keywords: electronic equipment, fluid flow, convection heat transfer introduction: electrical and mechanical engineering have long been aware of the potential thermal related reliability problems associated with high powered, high density of electronic circuitry. circuit designers have traditionally used prototype testing to monitor the thermal response of new circuit designs. but the prohibitive cost of prototype development both in terms of financial investment and in terms of time to deliver the finished product to market restrict the designer in this ability to developed on optimized thermal design. during the early stages of the design process the circuit designer is primarily concerned with determining the sensitivity of board temperatures to changes in basic design parameters, such as thermal conductivity of the board, flow velocity and package location (peterson, and ortega, 1990). conjugate problems can be divided into two parts, part one specialized with heat transfer phenomena on solid (printed circuit board pcb) and solve it using three-dimensional possion heat conduction in homogenous solid. the second part is to solve the governing equations for flow field region mass, momentum, energy and k- turbulence model. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. sattar j. habeeb/al-khwarizmi engineering journal, vol.3, no. 2 pp 17-31 (2007) 18 cooling of electronic equipment has been studied in great detail in recent years. there are a many papers, which have been written to analyze the flow pattern and thermal performance of printed circuit board pcb. the literature review is presented in subjective manner, and not in a comprehensive one. it is divided into three parts (thermal performance of pcb, flow field characteristics in enclosure, and turbulence modeling). icoz, t., verma, n., and jaluria, y. (2006) studied the heat transfer phenomena from multiple heat sources simulating electronic components and located in a horizontal channel. two experimental setups were fabricated for air and liquid cooling experiments to study the effects of different coolants. de-ionized water was used as the liquid coolant in one case and air in the other. the effects of separation distance and flow conditions on the heat transfer and on the fluid flow characteristics were investigated. the results from simulations and experiments were combined to create response surfaces and to find the optimal values of the design parameters. wang, q., and jaluria, y., (2002) found that inducing oscillations in the driving flow enhances the heat transfer rates from the heat sources and oscillatory flow is a common phenomena encountered in electronic cooling applications. icoz, t., and jaluria, y., (2005), used that concurrent simulation and experiment for design of cooling systems for electronic equipment, which consists of multiple heat sources in a channel. the conventional engineering design and optimization are based on sequential use of computer simulation and experiment. however, the conventional methods fail to use the advantages of using experiment and simulation concurrently in real time. chen, k. n., (2006), studied of a pcb carrying a heavy cpu cooling fan and supported by six fastening screws was investigated by the modal testing experiment and was analyzed by the finite element method. after the finite element model was verified by the experimental results, the locations of the six supporting screws were optimized to achieve a maximum fundamental frequency for the loaded pcb. lee, culham, and yovanovich (1991) examined some of common design parameters in design of microelectronic circuity such as the thermal conductivity and surface emissivity of the circuit board under forced convection condition. the flow velocity of the cooling fluid and the positioning and power dissipation on the heat sources are studies to determine the relative merit of each as a means of controlling circuit board temperatures. also they solved three-dimensional laplace equation for heat flow in homogenous solids in pcb and they solved boundary layer equations over the pcb based on blasius’s solution and coupling their solution to find temperature field in solid and flow domains. conjugate heat transfer problems in this problem can be extremely complex due to the interaction of the fluid and solid domains and the necessity for the governing equations in each domain to be satisfied simultaneously. lee, cuham, and yovanovich (1991) found the parameters on which the operating temperature depends in natural convection heat transfer and they showed the effect of these parameters such as the thermophysical properties, package location, and the applied power level on localized temperature and average nusselt number. finally they showed the effect of radiation and they recommended that the radiation must be included also as radiation may account for a significant fraction of the total heat dissipation from heat sources as well as from entire circuit board surface. lee, cuham, lenczyk, and yovanovich (1990) developed a conjugate model for airflow over flat plates with arbitrarily located heat sources based on the integral formulation of the boundary layer equations combined with a finite volume solution, which assumes twodimensional heat flow within the plate. the fluid and solid solutions are coupled through an iterative procedure, allowing a unique temperature profile to be obtained at fluid-solid interface, which simultaneously satisfies the this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. sattar j. habeeb/al-khwarizmi engineering journal, vol.3, no. 2 pp 17-31 (2007) 19 temperature field within each domain. lee, cuham, jeakins, and yovanovich (1992) used an analytical routine, meta to predict wall temperatures along a flat rectangular duct with heated rectangular modules attached to one surface. the rotationally dominant inlet velocity, resulting from an axial fan located at the entrance to the duct is approximated using a simple linear velocity variation across the principle flow direction. thermal simulation is compared to publish experimental data obtained over a range of channel reynolds number from (600 to 1800). this study examined the effect of these nonuniform inlet conditions on the surface temperature of board modules within the system. meta was used to simulate the thermal performance of populated circuit boards when inlet velocities were varied across the width of the circuit boards. afrid and zebib (1989) discussed a numerical study of natural convection air-cooling of single and multiple uniformly heated devices. a two-dimensional, conjugate, laminar flow model is used. they found that for the multi-component cooling, the effects of component thickness, the spacing between components, non powered components, and highly powered components are very important to arrive at qualitative suggestions that may improve the overall cooling of multicomponent system. they showed the results for the case of a single heated component, the temperature rise varies linearly with the heat generation for cases of many heated component, it was found that increased spacing between components and increased component thickness reduce the temperature rise. mahaney, ramadhyni, and incropera (1989) used a vectorized finite-difference marching technique. the steady state continuity, momentum, and energy equations are solved numerically to evaluate the effects of buoyancyinduced secondary flow on forced flow in a horizontal rectangular duct with a four-row array of (12) heat sources flush mounted to the bottom wall. also they showed that for a fixed rayleigh number and decreasing reynolds number, the row-average nusselt number decrease, reach a minimum, and subsequently increase due to buoyancy effect. thus, due to buoyancy-induced secondary flow, conditions exist for which heat transfer reducing the flow rate may enhance and hence the pump power requirement. mahaney, icropera, and ramadhyani (1990) investigated mixed convection heat transfer from a four-row, in-line array of (12) square heat sources that are flush mounted to the lower wall of a horizontal, rectangular channel. the experimental data encompass heat transfer regimes characterized by pure natural convection, mixed convection, laminar forced convection, where was water used as a coolant. in most literature surveyed, the literature of cooling of electronic component located in an enclosure can be divided into three parts. part one discussed analytical and numerical simulation of pcb and studies all the parameters that may effect the design of pcb. the aim of these studies is to maintain the operation temperature of the chips on pcb below the maximum allowable temperature as specified by various design constraints in order to ensure reliable performance of integrated circuits and to maintain minimum failure rates of components. the second part, covering with simulation of recirculating flow in enclosure and solving governing equations for mass, momentum and energy equations for flow field. in general for laminar flow and especially for turbulent flow, these procedures introduced under titles of cfd technique and its flexibility to solve these equations, with some studied for experimental analyses. the third part, covering the simulation of turbulent flow with k- turbulence model for solution of the governing equations. all these studies solved the problem of cooling of electronic component for two cases, solved the conduction heat transfer in pcb only, or solved the convection heat transfer in flow only, for laminar and turbulent flows. in present work will be solve the conduction and radiation heat transfer in pcb with convection heat transfer in flow domain and coupled these this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. sattar j. habeeb/al-khwarizmi engineering journal, vol.3, no. 2 pp 17-31 (2007) 20 two solutions in general form to present all domain, solid and fluid sides. the general transport equation the transport equations for continuity, momentum, energy, and the turbulence scales  and , all have the general form (awbi, 1998): φs z φ φz y φ φyx φ φx φ) w(ρ z )vφ(ρ y )uφ(ρ x φ)(ρ t                                            ……(1) where the terms on the left-hand side of equation (1) include the time-derivative and convective terms, and the terms on the right hand side include the diffusion and source terms. also, φ is the dependent variable and φs is the source term that has different expression for different transport equations. the convection and diffusion terms for all the transport equations are identical with φ representing the diffusion coefficient for scalar variables and the effective viscosity φμ for vector variables, i.e. the velocities. this characteristic of the transport equations is extremely useful when the equations are discretized (reduced to algebraic equations) and solved numerically since only a solution of the general equation (1) is required. in fact equation (1) also represents the continuity equation when φ =1 and φs = 0. table (1), gives the expressions for the source terms φs for each dependent variable that is likely to be needed in solving flow problems. table (1). source terms in the transport equations for laminar and turbulent flows. equation φ φ  φs laminar flow continuity ١ ٠ ٠ momentum u μ xρgxp  momentum v μ yρgyp  momentum w μ zρgzp  temperatur e t  q/cp turbulent flow continuity ١ ٠ ٠ momentum u eμ xρg )(xp   ueμ  momentum v eμ yρg )(yp   ueμ if we use the boussinesq approximation, we get rttδt t δt 1gyρg 0zρgxρg         where solution procedure: because of the non-linearity of the transport equations, an iterative method of solving the discretization equations to achieve a converged solution is the most plausible approach. an iteration solution starts from guessed values of the dependent variables for the whole field. in deriving the transport equations and their discretized forms there was no equation for pressure except that the pressure gradient was added to the source terms. however, to achieve a convergent solution it is obvious that for the velocity component u, v, and w obtained from a solution of the momentum equation to satisfy continuity, the correct pressure field must be used in the momentum equations. this link this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. sattar j. habeeb/al-khwarizmi engineering journal, vol.3, no. 2 pp 17-31 (2007) 21 between velocity and pressure can be employed in the iterative solution without the necessity of solving a discretization equation for the pressure (versteeg, and malalasekera, 1995). boundary conditions: due to the viscous influences near wall, the local reynolds number becomes very small, thus the turbulent model which is designed for high reynolds number become inadequate. both this fact and the steep variation of properties near wall necessitate special treatment for nodes close to the wall. one way of handling this problem is to use turbulence models in which modification has been introduced to take the viscous effects into account. the use of low-reynolds number models is one way. however, these models, when used near wall regions where the dependent variables and their gradient vary steeply, require a very fine mesh for adequate numerical solution and may lead to very high computational costs. the approach adapted in this program is called “ wall function ” as suggested by launder and spalding (1972). this treatment is based on the fact that the logarithmic law of the wall applies to the velocity component parallel to the wall in the region close to the wall, corresponding to a /νty.uy  value in the region 20030  y. in the following explanation of the treatment of turbulence quantities near the wall (davidson (1995)), it is assumed that the region near the wall consists of two layers. the layer nearest the wall is designated the ” viscous sublayer ” in which the turbulent viscosity is much smaller than molecular viscosity, i.e. the turbulent shear stress is negligible. ignoring the buffer layer, the second layer is designated the “inertial sublayer “in which the turbulent viscosity is much greater than molecular viscosity, making it a fully turbulent region. these two layers are the wall dominated regions and it is assumed that the total shear stress is constant, an assumption that is supported by experimental data. the point 11.63y is defined to dispose the buffer (transition) layer, and it corresponds to the intersection point between the log-law and the near-wall linear law. above this point the flow is assumed to be fully turbulent and below this point the flow is assumed to be purely viscous. then, the particularly simple onedimensional form of shear stress equation will become (davidson, and farhanieh, 1995): y u )tμ(μτ    ……(3) the wall function implemented in the present study can be summarized in table (2). table (2) wall function for vector and scalar transport and conditions at inlet and exit region. wall function for vectors transport equation for 11.63y where wττ , μ tμ  1 /νty.uy  for 11.63y where wττ , μ tμ 1 /νpy.uy  shear stress y pu tμy u tμwτ     y pu μ y u μwτ     viscosity )ln(ey1yκtuρtμ  ----turbulent kinetic energy 25.0 tp uck    ----energy dissipation 31 tu yκ ε 1 p   ----wall function for scalar transport for 11.63y where wqq 1, γ tγ for 11.63y where wqq  ,1 γ tγ heat flux parameter            ) tσ σ p(utσ )tw(ttuρ c wq p p where )twt( σy μ c wq p p  this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. sattar j. habeeb/al-khwarizmi engineering journal, vol.3, no. 2 pp 17-31 (2007) 22                     )) t /0.007/(( e28.01 10.75)(24.9)(      tt p condition at inlet region velocities u=uin , v=w=0. turbulent kinetic energy 2 i1.5 nuuiink 2  energy dissipation rate h/kε 1.5  condition at exit region normal velocity outa)(ρ in)a(ρ inuoutu  all vectors and scales parameters εk,p,w,v,u,φ ,0 x φ    thermal module: figure (1) demonstrated for 3d laminar and turbulent flow involving conjugate heat transfer. the flow is over a rectangular heatgenerating electronic chip, which is mounted on a flat circuit board. the heat transfer involves the coupling of conduction in the chip with radiation and convection in the surrounding fluid. the physics of conjugate heat transfer such as this is common in much engineering application, including the design and cooling of electronic components. in this study the electronic chip generate heat dissipation from 2-10 w and have a bulk conductivity of 1.0 w/m2.k, the circuit board conductivity is assumed to be of the order of magnitude lower than 0.1 w/m2.k. the airflow enters the system at 25 co with reynolds number changes for both laminar and turbulent cases. results: velocity vector and temperature contour around electronic chip. figures (2, and 3) show the velocity vector distribution and isothermal contours for laminar and turbulent flow respectively. in figure (2) where the flow is laminar, the velocity vector is assumed to be uniform at inlet region and buoyant flow is generated by buoyancy force after the location of electronic chip. then the buoyant flow arises and collides with the jet flow in enclosure. the jet flow in turbulent flow is strong compared with the same case in laminar flow, so the buoyant force becomes weak in this case. isothermal contours represent the flow behavior around electronic chip where the max. temperature in enclosure in laminar and turbulent cases are 94, and 74 co respectively effect of archimedes number on temperature rise percentage in the enclosure figure (4) represents the relation between temp. rise in the duct and ar for different cases, laminar and turbulent flow. in all curves the relation which represent a log scale for ar and the slope of the curve which increase according to increasing value of ar. this study applied for re=600 and 2800 according to inlet velocity. the power of electronic chip is changed in each test so the grashof number will be changed, therefore the archimedes number will be changed too. the relation indicated that for the same temp. rise the value of ar in turbulent flow is greater than in laminar flow. effect of heat dissipation from the electronic chip on temperature rise percentage in the enclosure figure (5) declares the effect of heat generation in the electronic chip on temp. rise in the duct, where the relation has the same behavior on both laminar and turbulent flows. the results shows that in turbulent flow, temp. rise is greater than for the case in the laminar flow at the same heat dissipation from the electonic chip. effect of archimedes number on average nusselt number figure (6) shows the effect of ar on average nusselt number for re=600, and 2800. for the same average nusselt number, we could see that, the range of ar between (0.6-2) in turbulent flow, but in laminar flow the range will become between (20-80). that lead to the fact this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. sattar j. habeeb/al-khwarizmi engineering journal, vol.3, no. 2 pp 17-31 (2007) 23 that in turbulent flow the heat dissipation from the chip is greater. effect of heat dissipation from the electronic chip on average nusselt number figure (7) shows the linear relation between average nusselt number for and heat dissipation from the electronic chip, the relation can be represent as below equation: qaaun  21 , where the constants a1, a2 are defend in below table: a1 a2 0.0533 2.0794 laminar flow 0.0529 2.0338 turbulent flow effect of heat dissipation from the electronic chip on rayleigh number figure (8) represents the relation between ra and q where the results show linear behavior between them for both cases. for the same heat dissipation from the electronic chip, the value of ra in turbulent flow is smallest than in laminar flow. the relation is represented by the equation: qaara *21 , where the constant a1, a2 are defined in below table: a1 a2 2.523 x 106 2.5 x 106 laminar flow 1.459 x 106 2.254 x 106 turbulent flow conclusions: the importance of computational modeling for flow cooling of the electronic chip was demonstrated. to simulate internal flow properly all factors have been clearly detailed. in recirculating flow with mixed convection heat transfer in duct, we could see proportional behavior between ar and un for different cases but the slopes of the curve lines are different according to value of ar. the flow patterns and isotherms do not show any significant difference between the cases of laminar or turbulent flow other than slight shift and changes in streamline and isotherm values. fig. 1 schematic diagram of the enclosure y z x pcb electronic chip dimenstion of the channel x-axis = 12 cm y-axis = 2.88 cm z-axis = 1.1 cm dimension of the channel x-axis = 12 cm y-axis = 2.88 cm z-axis = 1.1 cm electronic chip pcb inlet flow exit flow this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. sattar j. habeeb/al-khwarizmi engineering journal, vol.3, no. 2 pp 17-31 (2007) 24 fig. 2 velocity vector and isothermal contour for laminar flow re=600. z / lz = 0.81 z / lz = 0.72 z / lz = 0.63 z / lz = 0.45 x y z relative (grid units/magnitude)= 0.015 z / lz = 0.27 20 50 45 35 25 20 3025 20 52 42 35 30 22 40 20 94 74 50 79 52 35 25 21 30 22 69 20 94 89 64 89 69 50 40 30 22 35 25 20 94 69 55 45 35 30 25 42 this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. sattar j. habeeb/al-khwarizmi engineering journal, vol.3, no. 2 pp 17-31 (2007) 25 z / lz = 0.81 z / lz = 0.72 z / lz = 0.63 z / lz = 0.45 x y z relative (grid units/magnitude)= 0.015 z / lz = 0.27 20 29 2523 35 25 23 22 20 40 45 40 30 24 35 24 24 30 20 74 55 69 55 40 25 22 50 20 74 69 52 69 55 42 35 25 21 30 22 20 74 64 25 21 20 30 52 25 52 40 25 fig. 3 velocity vector and isothermal contour for turbulent flow re=2800. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. sattar j. habeeb/al-khwarizmi engineering journal, vol.3, no. 2 pp 17-31 (2007) 26 2 4 6 8 2 4 6 8 2 4 6 8 0 1 10 100 ar 14 18 22 26 30 16 20 24 28 (t ou tti n) /t ou t laminar flow (re=600) turbulent flow (re=2800) 1 3 5 7 9 0 2 4 6 8 10 q (watts) 14 18 22 26 30 16 20 24 28 (t ou tti n) /t ou t turbluent flow (re=2800) laminar flow (re=600) fig. 4 effect of archimedes number on temperature rise percentage in the enclosure fig. 5 effect of heat dissipation from the electronic chip on temperature rise percentage in the enclosure this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. sattar j. habeeb/al-khwarizmi engineering journal, vol.3, no. 2 pp 17-31 (2007) 27 2 4 6 8 2 4 6 8 2 4 6 8 0 1 10 100 ar 2 6 10 14 18 22 0 4 8 12 16 20 24 nu laminar flow (re=600) turbulent flow (re=2800) fig. 6 effect of archimedes number on average nusselt number. 1 3 5 7 9 0 2 4 6 8 10 q (watts) 2 6 10 14 18 22 0 4 8 12 16 20 24 nu turbulant flow (re=2800) laminar flow (re=600) fig. 7 effect of heat dissipation from the electronic chip on average nusselt number this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. sattar j. habeeb/al-khwarizmi engineering journal, vol.3, no. 2 pp 17-31 (2007) 28 references:  peterson, g. p., and ortega, a., 1990, “thermal control of electronic equipment and devices” advance in heat transfer, vol. 20, pp. 181-245.  icoz, t., verma, n., and jaluria1, y., 2006, “design of air and liquid cooling systems for electronic components using concurrent simulation and experiment,” asme j. heat transfer, vol. 128, december, pp. 466–478.  wang, q., and jaluria, y., 2002, “unsteady mixed convection in a horizontal channel with protruding heating blocks and a rectangular vortex promoter,” phys. fluids, vol. 14, pp. 2109–2112.  icoz, t., and jaluria, y., 2005, “design of cooling systems for electronic equipment using both experimental and numerical inputs,” asme j. electronic packaging, vol. 126, no. 4, pp. 465–471.  chen, k. n., 2006, “optimal support locations for a printed circuit board loaded with heavy components,” asme j. electronic packaging, vol. 128, december, pp. 449–455.  lee, s., culham, j. r., and yovanovich, m. m., 1991, “the effect of common design parameters on the thermal performance of microelectronic equipment: part ii – forced convection”, asme, heat transfer in electronic equipment, htd-vol. 171, pp. 55-62.  lee, s., culham, j. r., and yovanovich, m. m., 1991, “the effect of common design parameters on the thermal performance of microelectronic 1 3 5 7 9 0 2 4 6 8 10 q (watts) 5.00e+6 1.50e+7 2.50e+7 3.50e+7 0e+0 1e+7 2e+7 3e+7 4e+7 ra laminar flow (re=600) turbulemt flow (re=2800) fig. 8 effect of heat dissipation from the electronic chip on rayleigh number. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. sattar j. habeeb/al-khwarizmi engineering journal, vol.3, no. 2 pp 17-31 (2007) 29 equipment: part i – natural convection”, asme, heat transfer in electronic equipment, htd-vol. 171, pp. 47-54.  lee, s., culham, j. r., lemczyk, t. f., and yovanovich, m. m., 1990, “ metaa conjugate heat transfer model for air cooling of circuit boards with arbitrarily located heat sources”, 1990, asme, htd, heat transfer in electronic equipment, vol. 171, pp.117126.  lee, s., culham, j. r., jeakins, w. d., and yovanovich, m. m., 1992, “thermal simulation of electronic systems with non-uniform inlet velocities”, asme, computer aided design in electronic packaging, eepvol. 3, pp. 33-40.  afrid, m., and zebib, a., 1989, “ natural convection air cooling of heated components mounted on a vertical wall”, j. numerical heat transfer, part a, vol. 15, pp. 243-259.  mahaney, h. v., ramadhyani, s., and incropera, f. p., 1989, “ numerical simulation of three-dimensional mixed convection heat transfer from an array of discrete heat sources in a horizontal rectangular duct ”, j. numerical heat transfer, part a, vol. 16, pp. 267-286.  mahaney, h. v., incropera, f. p., and ramadhyani, s., 1990, “ comparison of predicted and measured mixed convection heat transfer from an array of discrete sources in a horizontal rectangular channel “int. j. heat mass transfer, vol. 33, no. 6, pp. 1233-1245.  awbi, h. b., 1998 “ ventilation of buildings ”, by e & fn spot.  versteeg, h. k., and malalasekera, w., 1995, “ an introduction to computational fluid dynamics: the finite volume method “, longman scientific & technical (longman group limited).  lundar, b. e., and spalding, d. b., 1972, “mathematical models of turbulence “, academic press., london.  davidson, l., and farhanieh, b., 1995, “a finite-volume code employing collocated variable arrangement and cartesian velocity components for computation of fluid flow and heat transfer in complex threedimensional geometries “, dept. of thermoand fluid dynamics, chalmers university of technology, sweden, november, publ. no. 95/11.  schlichting, h., 1995, “boundary layer theory “, seventh edition, mcgrawhill. nomenclature ar archimedes number (gr / re2 ) cp specific heat (j/kg.k) μ21 cc,c,c d , coefficient in turbulence models g gravitational acceleration (m/sec2) gr grashof number bg buoyancy production kg generation rate of turbulence energy h enclosure height (m) h convective heat transfer coefficient (w/m2.k) iu turbulence intensity k turbulent kinetic energy (m/sec2) p pressure (n//m2) q power dissipation from heat element (w) wq wall heat flux (w/m2) re reynolds number this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. sattar j. habeeb/al-khwarizmi engineering journal, vol.3, no. 2 pp 17-31 (2007) 30 s general source term t temperature ( c ) skwr t,t,t reference , wall and surrounding temperature respectively ( c ) u, v, w mean velocity components (m/sec) u, v, w component of velocity vector in x, y, and z direction (m/sec) τu friction velocity (m/sec) x, y, z physical or cartesian coordinates (m) greek symbol γ diffusion coefficient ε energy dissipation (m2/sec3)  constant (0.005) 1κ von karmen constant (0.41) μ dynamic viscosity (n/sec.m2) ν kinematics viscosity (m2/sec) ρ fluid density (kg/m3) 1σ stefan-boltzmann constant (5.67x10-8 ) (w/m2 .k4) σ prandtl / schmidt number τ shear stress (n/m2)  dependent variables subscript e effective condition in inlet condition out outlet condition r reference value t turbulent p st. point near the wall w condition at wall e effective condition this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. sattar j. habeeb/al-khwarizmi engineering journal, vol.3, no. 2 pp 17-31 (2007) 31 بحث ظاھرة انتقال الحرارة وتصرف الجریان حول جزء إلكتروني ستار جابر حبیب. د قسم ھندسة المكائن والمعدات الجامعة التكنولوجیة :الخالصة جزء (تّم عرض دراسة نظریة لجریانات طباقیة واضطرابیة ثالثیة األبعاد حول مصدر تسخین ، تضمنت الدراسة حل المعادالت التفاضلیة الجزئیة pcb موضوع فوق صفیحة إلكترونیة ) إلكتروني األھلیلیجیة المتمثلة بحفظ الكتلة، الزخم، الطاقة ، الطاقة المضطربة ومعدل ضیاعھا باستخدام الحجوم المحددة )finite volumes .( لقد حلت ھذه المعادالت باستخدام نموذج k-ε باإلضافة إلى استخدام مفھوم دالة كما تّم االعتماد على الخوارزمیة . لجدار بالقرب من الجدران لمعالجة تأثیرات االضطرابا (simple algorithm) الجزء إلكتروني یبرد بواسطة ھواء خارجي یمر خالل . في بناء ھیكلیة البرنامج إللكتروني الموضوع داخل الحیز وكیفیة أھداف البحث تتمثل في بحث ظاھرة انتقال الحرارة للجزء ا. الحیز ھذه المتغیرات سوف تساعدنا على تصور األداء الحراري للجزء , الوصول إلى افضل مستوى تبرید لھ النتائج . ت مختلفة على شكل الجریاناإللكتروني وشكل تیارات الجریان المتكون من خالل فھم تأثیر معامال ,ar) مع (nu, ra)وضحت العالقة بین معدل ارتفاع درجة الحرارة داخل الحیز ومعامالت انتقال الحرارة q)لحالتین من الجریان الطباقي واالضطرابي. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ الهمزة al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 5, no. 2, pp 1 9 (2009) modeling and filtering for tracking maneuvering targets sadiq j. abou-loukh electrical engineering department / college of engineering / university of baghdad (received 1 september 2008; accepted 25 may 2009) abstract a new mathematical model describing the motion of manned maneuvering targets is presented. this model is simple to be implemented and closely represents the motion of maneuvering targets. the target maneuver or acceleration is correlated in time. optimal kalman filter is used as a tracking filter which results in effective tracker that prevents the loss of track or filter divergency that often occurs with conventional tracking filter when the target performs a moderate or heavy maneuver. computer simulation studies show that the proposed tracker provides sufficient accuracy. keywords: kalman filter, modelling and filtering, tracking maneuvering targets. 1. introduction for years lots of effort has been spent on the development of sophisticated digital filtering algorithms for tracking maneuvering targets. these algorithms can be classified into classical and modern. the classical algorithms include least squares and polynomial filter [1, 2, 3], wiener filter [4], and α – β filter [5, 6]. the two-point extrapolator is considered as a non-recursive filter and can be implemented without any need for a storage device [3]. the function of this filter is simply obtained through the use of the last two data points. the other simple approach is the wiener filter. it is a constant gain filter which is equivalent to the steady state gain of the regular kalman filter [7]. wiener filter does not require the calculation of the covariance elements; thus this filter does not account for the variation and the statistics in the target maneuver. furthermore, this scheme incurred the problem of tracking both the maneuvering and non maneuvering targets with the same accuracy, as well as might even loose the track or diverge. the α – β filter is another classical tracking scheme extensively utilized in most modest tracking scenarios [5, 6]. it is designed to minimize the mean square error in the filtered state under the assumption that the target moves along straight line trajectory, so it has small capability to track severely maneuvering targets. for this reason, various maneuvering detectors are often attached to facilitate its job against evasive vehicles. the modern algorithms involve the use of state space estimation and adaptive kalman filtering [8]. gurfil et. al. [9] suggest an attractive alternative method to the standard kalman filter to optimally estimate three dimensional states of maneuvering target in two steps: the first is linear and the second is nonlinear. another technique described by sinha et. al. [10], involves switching between the kalman-levy filter and the standard kalman filter. the kalman-levy filter is more effective in response to large error due to the onset acceleration or deceleration; while the performance of this filter is worse in the nonmaneuvering portion. for this reason the system switched to the standard kalman filter. in this paper a simple and accurate target model is developed. the maneuver equations are derived for the actual continuous time target motion and then expressed in discrete time according to the standard discretization procedure providing accurate statistical representation of the true target behavior [11]. the remaining parts of this paper are devoted to dynamic equation of target maneuver, discrete time target equations of motion, optimal kalman tracking filter and computer simulation. sadiq j. abou-loukh al-khwarizmi engineering journal, vol. 5, no. 2, pp 1 9 (2009) 2 2. dynamic equations of target maneuver the model stimulated in this section is based on the fact that without maneuver the target under consideration, e.g. aircraft, generally follows a straight line constant speed trajectory. turn, evasive maneuvers and accelerations due to atmospheric turbulence may be viewed as perturbations on this flying trajectory. the continuous time target equation of motion may be represented by [11]: )(.)(.)( tagtxftx dt d  … (1) where: a(t) is target acceleration     )( )( )( tv tr tx and        1 0 g the acceleration term a(t) is assumed to be white gaussian noise. the normality assumption of the noise is one of the necessary conditions for applying the theory of optimum kalman filter [7]. however, the whiteness here seems to be inappropriate justification for the real-world auto commanded vehicles. for such vehicles, the target acceleration and hence the target maneuver are correlated in time: namely, if the target is accelerated at time t, it is likely to be accelerated at time (t + τ) for sufficiently small τ. for example, a lazy turn will often give rise to correlated acceleration inputs for up to one minute; evasive maneuvers will provide correlated acceleration inputs for periods between ten to thirty seconds and atmospheric turbulence may provide correlated acceleration inputs for one to two seconds. a typical representative model of the correlation function c(τ) associated with the target acceleration is assumed to be:  0)(.)()( //2   betataec b m  … (2) where, 2 m is the variance of the target acceleration and b is the reciprocal of the maneuver (acceleration) time constant. for example: b ≈ 1/60 for a lazy turn, b ≈ 1/20 for an evasive maneuver and b ≈ 1 for atmospheric turbulence. now, taking the laplace transform of both sides of eq. (2) and by partitioning the result, one can get … (3) where : γ { . } is the laplace transform operator, and the term h(s) is the transfer function of the physical shaping filter for a(t), and w(s) is the transform of the white noise w(t) that drives a(t). the resulting equation of the shaping filter in time domain is )()(.)( twtabta  … (4) for which )(wc is the correlation function of the input white noise which satisfies )(..2)( 2 tbc mw   … (5) this secondary system is blended with the pervious two state per coordinate target model eq.(1) to obtain the overall augmented target model which is driven by a white noise w(t) as follows : )(.)(.)( twgtxftx dt d  … (6) where :            )( )( )( )( ta tv tr tx w(t) is a zero mean white gaussian noise driving function with covariance equal to 22 mb ,            b f 00 100 010 and            1 0 0 g        00 10 f   )(.)(.)( )()( 2 )()( 2 swshsh bsbs b csc m            (5) (6) target range at time t target velocity at time t 22)( )( 1 )( mbsw bs sh    sadiq j. abou-loukh al-khwarizmi engineering journal, vol. 5, no. 2, pp 1 9 (2009) 3 3. discrete time target equations of motion the discrete form of the target model can readily be found by discretizing the continuous form of the target equation of motion described in eq.(6) by simply using the standard discretization procedure explained in [11] . this is done by integrating eq.(6) over the interval (t , t+t) to get  dwgetxettx tt t ttftf )(.)(.)( ))((    … (7) rewriting eq.(7) in appropriate form, then )()(.),1()1( kukxkkkx   … (8) where )( 12 12),(    f e    dwgeku tk kt tkf .)(..)( )1( )1(    … (9) and t = kt it can be easily verified that the state transition matrix ),1( kk  is … (10) and when bt is small, this matrix can be reduced to the newtonian matrix            100 10 2/1 2 t tt  … (11) furthermore, the input vector of the maneuver excitation noise u(k) given in the target model eq.(8) is not equivalent to the sampled version of the continuous time white noise w(t) as it is seen in eq.(9). after substituting f and g in eq.(9), the input noise vector is determined as follows : w(τ)dτ … (12) since w(t) is a zero mean white gaussian noise, then u(k) is a discrete time white gaussian sequence with zero mean and covariance matrix q(k):     )(.)()(.)( 0)( jkkqjukue kue t    … (13) where: δ(.) is kronecker delta symbol, and … (14) after substituting the matrices g , tg ,  and t in eq. (14), the covariance matrix is simplified to:            333231 232221 131211 2.2 qqq qqq qqq b m … (15) where: (15)    tk kt tt m dtkgbgtkkq )1( 2 ).,)1((2.),)1(()(               tk kt m d nnnnn nnnnn nnnnn bkq )1( 2 32313 32 2 212 3121 2 1 2 )()()()()( )()()()()( )()()()()( .2)(                              bt bt bt e e b ebt b t kk 00 ]1[ 1 10 1 1 1 ),1( 2                          bt bt bt e e b ebt b t kk 00 ]1[ 1 10 1 1 1 ),1( 2                          bt bt bt e e b ebt b t kk 00 ]1[ 1 10 1 1 1 ),1( 2  bte ),1( kk                                           tkb tkb b tkb tkb b ku tk kt )1(exp ])1([exp1[ 1 )1(exp )1(1[ 1 )( 2 )1(           2332 1331 1221 2 33 2 223 2 322 2 313 222 412 22 33 2 511 1 2 1 .21 2 1 23.4 2 1 .21 2 1 2221 2 1 .42 3 2 21 2 1 qq qq qq e b q ee b q btee b q ebte b q tbbtebtee b q ebttb tb bte b q bt btbt btbt btbt btbtbt btbt                      ] exp[-b{(k+1)t-τ}]]                                          tkb tkb b tkb tkb b ku tk kt )1(exp ])1([exp1[ 1 )1(exp )1(1[ 1 )( 2 )1( exp[-b{(k+1)t-τ}]              tk kt dw n n n)1( 3 2 1 )(. )( )( )(     sadiq j. abou-loukh al-khwarizmi engineering journal, vol. 5, no. 2, pp 1 9 (2009) 4 when bt is sufficiently small then               ttt ttt ttt bkqlimit m bt 26 238 6820 2)( 23 234 345 2 0  reflecting the fact that for sufficiently short time periods the physical target moves at essentially constant velocity. for a fixed sampling period t, as b → ∞ furthermore, to be able to apply the theory of optimal kalman filtering, an output equation is needed to supply the desired information about the system. along each independent coordinate (range, elevation or azimuth angle) being analyzed and processed, an observation or output model should be defined. this model describes the tracking sensor or measuring channel which is simply modeled as a sampled version of the observation disturbed by an additive white gaussian noise corrupting the measured information. again the range channel is considered here as follows: )()()( knkrky rr  … (16) where: yr(k) is the measured range, r(k) is the exact range, nr(k) is the additive white gaussian noise uncorrelated with u(k) and have the following statistics   0)( kne r   )(.)(.)( 2 ikinkne rrr     .&0)(.)( ikallforiukne r  and 2 r is the variance of the observation channel noise. rewriting eq.(16) in terms of the target state, )()(.)( knkxhky rr  … (17) where:  001h is the observation matrix. the target and observation model for elevation angle )(k and azimuth angle β(k) can be easily derived using exactly the same manipulations that are used to derive the range model. however, the final form of these models are given here and as follows : elevation angle target model : )()(.),1()1( kukxkkkx eee   observation model : )()(.)( knkxhky eee  prior statistics:   0)( kue e         kiallforinkue ikinkne ikkqiukue kne ee eee e t ee e &0)(.)( )(.)(.)( )(.)()(.)( 0)( 2       matrices:            100 10 2/1 ),1( 2 t tt kk , , and azimuth angle target model : )()(.),1()1( kukxkkkx aaa   observation model : )()(.)( knkxhky aaa  prior statistics:   0)( kue a             200 000 000 )( m b kqlimit            2332 1331 1221 2 33 2 223 2 322 2 313 222 412 22 33 2 511 1 2 1 .21 2 1 23.4 2 1 .21 2 1 2221 2 1 .42 3 2 21 2 1 qq qq qq e b q ee b q btee b q ebte b q tbbtebtee b q ebttb tb bte b q bt btbt btbt btbt btbtbt btbt                       001h  t e kkkkx )()()()(   sadiq j. abou-loukh al-khwarizmi engineering journal, vol. 5, no. 2, pp 1 9 (2009) 5         kiallforinkue ikinkne ikkqiukue kne aa aaa a t aa a &0)(.)( )(.)(.)( )(.)()(.)( 0)( 2       matrices :            100 10 2/1 ),1( 2 t tt kk ,  001h , and   t a kkkkx )()()()(   where: )(,)(,)( kkk   are elevation angle, first and second derivative of elevation angle respectively, )(,)(,)( kkk   are azimuth angle, first and second derivative of azimuth angle respectively, 22 , ae  are the error (variance of observation channel noise) in the measured elevation and the azimuth angles respectively, )(,)( kyky ae are the measured elevation and the azimuth angles respectively. it is clear that the developed models for range, elevation and azimuth channels are decoupled, because there is no cross-coupling or dependence between any two associated items of any channel. thus, these coordinates can be processed and estimated via implementing three independent tracking filters. 4. optimal kalman tracking filter the aforementioned target and observation models for range, elevation and azimuth coordinates have similar aspects and they are suitably to confirm the requirements of implementation kalman filtering algorithm. it is recommended here to define kalman tracking filter for one channel only (the range channel), while the others are exactly the same. the following equations summarize the recursive kalman tracking filter for the range coordinate [7]: target model: )()(.),1()1( kukxkkkx   observation model : )()(.)( knkxhky rr  filtered estimate: predicted estimate: )/(ˆ.)/1(ˆ kkxkkx  kalman gain:   12)/1(..)/1()1(  r tt hkkphhkkpkk  covariance matrix of predicted error: )(.)/(.)/1( kqkkpkkp t   covariance matrix of filtered error:   )/1(.)1()1/1( kkphkkikkp  estimate of maneuvering target range coordinate by these kalman filter recursive equations require an initial estimates of )0/0(x̂ and )0/0(p to be inspired. the initialization is based on the first two observations as follows: )0()0/0(ˆ ryr    t yy v rr )0()1( )0/0(ˆ   0)0/0(ˆ a   tavrx )0/0(ˆ)0/0(ˆ)0/0(ˆ)0/0(ˆ  where: yr(0) and yr(1) are, respectively, the first and second received sensor measurements. the corresponding covariance matrix of the filtered error estimated is defined as: 2 11 )0/0( rp  tpp r /)0/0()0/0( 2 2112  22 22 /2)0/0( tp r 5. computer simulations computer simulation studies are used to verify, compare and evaluate the performance of the developed model. the tracking filter is exercised under different flight environments. tracking  )/(ˆ..)1( .)1()/(ˆ.)1/1(ˆ kkxhky kkkkxkkx r      )/(ˆ..)1( .)1()/(ˆ.)1/1(ˆ kkxhky kkkkxkkx r      )/(ˆ..)1( .)1()/(ˆ.)1/1(ˆ kkxhky kkkkxkkx r      )/(ˆ..)1( .)1()/(ˆ.)1/1(ˆ kkxhky kkkkxkkx r     0)0/0()0/0()0/0()0/0()0/0( 3332233113  ppppp 0)0/0()0/0()0/0()0/0()0/0( 3332233113  ppppp sadiq j. abou-loukh al-khwarizmi engineering journal, vol. 5, no. 2, pp 1 9 (2009) 6 performance is evaluated by tracking an accurate figure given by:  2 1 2 . )/(ˆ)( 1 )(    n i est iirir n r where it is interpreted as the root-mean-square (rms) of the range estimate error of n estimated points on the tracked trajectory. however, computer simulation requires two additional subroutines. the first is used to generate a wide class of maneuvering target trajectories, from lightly to heavily maneuvered targets and with three different turns ( 90º , 180º, 270º ). the second subroutine generates a white gaussian noise with different strengths representing the additive observation channel corruptions (.)rn . for different cases are examined as follows: case one: different target aviations are simulated and unified to the datum of mr 150 , st 1.0 , initial velocity smv /500)0(  . the target performs three independent turns of 90º, 180º, and 270º for each single flight and with different accelerations: 1, 10, 20, 30, 40, and 50 m/s 2 . these trajectories are generated and sampled at an interval t=0.1 s. observations are formed using white gaussian noise generator with the specified standard deviation ( mr 150 ). for each run, 1200 observations (n=1200) are constructed. these data are then filtered by standard kalman filter based on the developed model assuming a moderate value for  2/2 smmm  and for all trajectories. the tracking accuracy is computed (mse) using 1200 estimated points. the results are listed in table (1). table 1, range tracking accuracy for different target maneuvers and turns. target acceleration ( m/s 2 ) range tracking accuracy mrest )(. 90º turn 180º turn 270º turn 1 10 20 30 40 50 38.67 38.89 40.53 46.65 49.84 55.26 38.73 40.62 43.40 48.17 53.31 58.07 39.32 40.93 44.76 48.52 54.16 58.78 case two: for the purpose of evaluating the tracking accuracy of the proposed tracker, the tracking performance of the proposed tracker is compared with the performance of other tracking filters such as α – β filter [6] and wiener filter [4] under different flight environments. it is assumed that 1200,1.0,150  nstmr and 90º turn. computer results are shown in table (2). table 2, range tracking accuracy of different filters. target acceleration ( m/s 2 ) tracking accuracy mrest )(. proposed filter α – β filter wiener filter 1 10 20 30 40 50 38.67 38.89 40.53 46.65 49.84 55.26 30.71 36.13 72.62 divergent divergent divergent 28.26 34.88 78.04 divergent divergent divergent it is clearly seen from these results that wiener filter and α – β filter are suitable only for tracking non-maneuvering or slowly fluctuating targets. case three: all parameters in target and observation models can be specified with sufficient accuracy before processing the trajectory of enemy maneuvering target except for the variance of the target acceleration or maneuver since this parameter describes the target behavior or statistic of target maneuverability during its flight. actually, the target usually behaves in undetermined aspects unknown to the tracking filter. this fact leads to incorrect choice of m and hence degradation in filter tracking accuracy. the effect of uncertainty in m on the range tracking accuracy is investigated by simulating various trajectories with the following parameters: mst r 150,1.0   , 90º turn and a = 1, 10, 20, 30, 40, and 50 m/s 2 and processing each trajectory using three different values of m as : . the results are listed in table (3). the symbol * in each row of table (3) denotes the highest tracking accuracy achieved for the considered target maneuver or acceleration. it is 222 /5/2,/5.0 smandsmsm sadiq j. abou-loukh al-khwarizmi engineering journal, vol. 5, no. 2, pp 1 9 (2009) 7 well evident from these results that for lightly maneuvered target ( a ≤ 10 m/s 2 ) 2/5.0 smm  is more suitable while for heavily maneuvered targets ( a ≥ 30 m/s 2 ) 2/5 smm  is more suitable than 5.0m or 2/2 sm . table 3, range tracking accuracy for different standard deviation of target acceleration. target acceleration ( m/s 2 ) range tracking accuracy mrest )(. 2/5.0 smm  2/2 smm  2/5 smm  1 10 20 30 40 50 24.13* 25.30* 49.06 78.82 106.55 129.28 38.67 38.89 40.53* 46.65 49.84 55.26 63.22 54.87 48.45 42.13* 44.28* 51.76* case four: although 2/5.0 smm  and 2/5 smm  provide high tracking accuracy for processing trajectories of lightly and heavily maneuvered targets respectively; however, these values are not the proper or optimum m . in this run, optimal value of m , that yields the highest tracking accuracy, is searched for the simulation trajectories of case three. these attributes are shown in table (4). table 4, range tracking accuracy at optimum standard deviation of target acceleration for different target maneuvers. target acceleration ( m/s 2 ) range tracking accuracy mrest )(. optimum )/( 2smm 1 10 20 30 40 50 19.37 23.68 28.76 29.53 28.13 30.49 0.02 0.8 3.2 5.9 6.7 8.3 these results show that optimal variance of target acceleration varies in wide extents and have great influence on the tracking performance of the filter. 6. conclusion using a simple target model that accounts statistically for the magnitude and duration of target maneuver has shown how a kalman filter can be constructed to track maneuvering targets. the important features of the presented target model are : firstly, it is simple to be implemented, secondly, it is able to describe wide class of maneuvering target trajectories from lightly to heavily maneuvered targets, and thirdly, it is derived in a decoupled form for the range, elevation and azimuth angles. thus, these coordinates can be processed and estimated via implementing three independent tracking filters. this advantage facilitates the tracker activity in two ways. first, the computational efforts are greatly reduced since the overall system dimension is reduced from 9 x 9 to three separate models of 3 x 3 dimensional subsystems for each coordinate. secondly, the system reliability is further enhanced when applied for on-line tactical combat conditions. the tracking performance of the proposed kalman filter has been analyzed and tested by using different computer simulation studies. it is shown that using the proposed filter, the error in sensor range measurement is reduced from )150(150 mm r  to (40 – 60) meters depending on the target maneuverability as shown in table (1). the tracking performance of the filter is also compared with the – β tracking filter [5, 6] and wiener filter [4] under various flight environments. these two filters exhibit higher tracking accuracy than the suggested kalman filter. in case of applying these two filters in real world, the filter may lose the track or diverge when the target performs moderate or heavy maneuver (a≥30 m/s 2 table (2)) while the target presented here will never diverge. the main problem addressed by computer simulation studies is the degradation in tracking performance due to uncertainty in model parameters especially the variance of target acceleration 2 m . a comparison between table (4) and table (3) illustrates how the tracking accuracy is significantly improved when m is properly sadiq j. abou-loukh al-khwarizmi engineering journal, vol. 5, no. 2, pp 1 9 (2009) 8 selected to fit the target maneuver. in all computer simulation studies, it is assumed that m is constant for the whole trajectory; however, this assumption is not always correct. thus, the demand for on-line adaptation of m is greatly highlighted to enhance the filter performance in front of any sudden changes encountered during target flight trajectory. 7. references [1] eli brooker, " tracking and kalman filtering made easy ", john wiley & sons, inc., 2001. [2] lennert ljung, " system identification theory for the user ", prentice hall, inc., 1999. [3] c. schell, s.p. linder and j.r. zeidler, "tracking highly maneuverable target with unknown behaviour", proceedings of the ieee, vol. 92, no.3, pp. 558-574, march 2004. [4] x.r. li and v.p jilkov, "survey of maneuverable target tracking-part i: dynamic models", ieee trans. on aerospace and electronic systems, vol. aes-39, issue4, pp. 1333-1364, oct. 2003. [5] jae-chem yoo and young-soo kim, "alphabeta tracking index (α-β-λ) filter", signal processing, elsevier, vol.83, issue 1, pp. 169180, jan. 2003. [6] t.l. ogle and w.d. blair, "fixed-lag α-β filter for target trajectory smoothing, ieee trans. on aerospace and electronic systems, vol. aes-40, issue 4, pp. 1417-1421 oct. 2004. [7] dan simon, "optimal state estimation: kalman h-infinity and nonlinear approaches", john wiley & sons, inc., 2006. [8] y. yu and q. cheng, "particle filters for maneuvering target tracking problems", signal processing, elsevier, vol. 86, issue 1, pp. 195-203, jan. 2006. [9] p. gurfil and n.j. kasdin, "two step optimal estimator for three dimensional target tracking", ieee trans. on aerospace and electronic systems, vol. aes-41, issue 3, pp. 780-793, july 2005. [10] a. sinha, t.k. barajan and y. bar-shalom, "application of the kalman-levy filter for tracking maneuvering targets", ieee trans. on aerospace and electronic systems, vol. aes-43, issue 3, pp. 10971107, july 2007. [11] c.k. chui, "kalman filtering: with real-time applications", second edition, new york, springer-verlag, 1999. . 9 1، صفحة 2، العذد 5مجلة الخىارسمي الهنذسية المجلذ صادق جاسم ابى اللىخ (200 9) 9 النمذجة والتزشيح لمتابعة األهذاف المناورة صادق جاسم ابى اللىخ صايعت بغذاد / كهيت انُٓذست / قسى انُٓذست انكٓشبائيت : الخالصة يخًيز ْزا األًَٕرس انشياضي بسٕٓنت انخُفيز ٔدقت حًزيم حشكت األْذاا .ةيُأسَر ال ْذااِف األ نخًزيم حشكتسياضي صذيذ يخضًٍ ْزا انبحذ بُاء إًَٔرس (tracking) نيكٌٕ يششح انًخابعت (kalman filter)نقذ حى أسخعًال يششح كانًاٌ انًزاني . أٌ يُأسة انٓذا أٔ حعضيهّ يكٌٕ يخشابط يع انزيٍ .انًُأسة انزي حقق يخابعت يؤرشة بحيذ ال يضال نفقذاٌ يخابعت انٓذا أٔ األَحشاا عُّ كًا يحذد عُذ أسخخذاو يششحاث انًخابعت انخقهيذيت عُذيا يقٕو انٓذا بًُأسة .حى يحاكاة ْزِ انطشيقت بأسخخذاو انحاسٕب ٔححج ظشٔا يخابعت يخخهفت ٔكاَج انُخائش انُٓائيت راث دقت يقبٕنت. يعخذنت أٔ شذيذة 7989 al-khwarizmi engineering journal al-khwarizmi engineering journal,vol. 12, no. 1, p.p. 7989 (2016) synthesis and characterization of nanocrystalline zeolite y nada s. ahmedzeki* selahattin yilmaz** ban a. al-tabbakh*** * department of chemical engineering/ college of engineering/ university of baghdad ** department of chemical engineering / izmir institute of technology/ izmir/ turkey ***petroleum research and development center/ ministry of oil/ baghdad email: dr_ahmedzeki@yahoo.com email: selahattinyilmaz@iyte.edu.tr email: banaltabbakh@hotmail.com (received 22 june 2015 ; accepted 20 october 2015) abstract worldwide attention is being focused on nanocrystalline zeolites and they are replacing conventional ones due to their pronounced potential in many fields. in this study, nay zeolite has been prepared hydrothermally using sol –gel method and modified to the proton type by ion –exchange process. characterization is made using x-ray diffraction (xrd), thermogravimetric analysis (tga), fourier transform infrared spectroscopy (ftir), atomic force microscopy (afm), brunauer –emmetteller (bet) nitrogen adsorption method, ammonia temperature programmed desorption (nh3-tpd) and scanning electron microscopy( sem). the effect of aging time, silica to alumina ratio is studied and the results show well defined crystalline structure with nano particle size (70 and 81nm) with surface area of 499m2/gm. keywords: zeolite y, nanozeolite, sol-gel method, characterization. 1. introduction since their introducing in petroleum industry , zeolites provide the great role in many catalytic and petrochemical processing such as in the yield of high octane gasoline or in water filtration and purification in addition to their impact in producing cleaner fuels and lubricants [1]. zeolites are aluminosilicates materials having a highly ordered crystal structure. the three dimensional network structured of sio4and alo4tetrahedral which provide the cavities of the zeolite [2]. often zeolites are prepared hydrothermally from a period of time of many hours to few days. the reaction gel mixture provided from silicon source and aluminum source under alkaline state in different concentration and suitable aging and crystallization time to reach the final crystalline zeolite[3]. according to many function of zeolite such as solid acidity, shape selectivity and loading properties, nano-sized zeolites were prepared and became a challenge to obtain unique properties relative to microcrystalline zeolite having a high surface area and small particle size of less than 100nm [4,5]. nano crystalline y zeolite having more acid sites on its surface, large pore volume exhibites higher stability and higher activity in many application such as in fluid catalytic cracking reveal to their good diffusion of reactants and products and producing more gasoline and lighter gas oil [6,7]. zeolite y displays the faujasite type structure having a 3-dimensional structure with pores being perpendicular to each other in the x, y, and z. it is constructed from sodalite cages with crystalline cubic structure having a characteristic pores of 7.4ao. also, it can be characterized by its silica to alumina ratio of (4 to 6) which differs than the other faujasite type ; zeolite x which have this ratio as 2 to 3 while for type a is 2. the acidity of zeolite y is motivated by its application as a solid catalysts, therefore the study of the acid site became inevitable several methods had been successfully applied to study the active sites present on zeolites, and most of them are based on the adsorption or desorption of gas phase nada s. ahmedzeki al-khwarizmi engineering journal, vol. 12, no. 1, p.p.79 89 (2016) 80 probe molecules, which are chosen on the basis of their reactivity and molecular size. nh3-tpd is a widely used, simple and inexpensive technique for reflecting the surface acidity of a catalyst, where the temperature dependence in the desorption step is related to the acid sites present which may involve physical or chemical adsorption [8]. preparation of nano zeolites is widely experienced with different methods and precursors. therefore, microwave and ultrasonic methods, templates and surface modifiers are used mostly in teflonlined stainless steel autoclaves [9]. in this study, a facile method for the preparation of nonocrystalline zeolite y is investigated using clear hydrothermal synthesis. extensive characterization of the final product was done using (xrd), (tga) (ftir), (afm), (sem), (nh3-tpd),( bet). 2. experimental sodium aluminate (naalo2), sodium silicate solution (na2sio3) supplied by sigma-aldrich, sodium hydroxide (naoh) by merck were used. zeolite y was synthesized according to sol-gel method. seeding gel is prepared by adding 19.95 gm of deionized water to 4.07 gm of sodium hydroxide and 2.09 gm sodium aluminate [10,11]. the mixture was stirred in a plastic bottle until dissolved then 28.3gm of sodium silicate solution was added and stirred moderately for at least 10 min. then the seed gel was aged for different aging time of 24,48 and 72 hr at room temperature. the feed stock gel was prepared by mixing 131 gm of deionized water, 0.14 gm sodium hydroxide and 13gm sodium aluminate. stirring was continued in 500 ml plastic beaker until the constituents were completely dissolved, then 178 gm of sodium silicate solution was added with stirring vigorously at 1600 rpm until smooth gel was obtained. the final gel is prepared by adding 16.5 gm of aged seed gel to feed stock gel slowly with mixing up for 20 min. at 1600 rpm..after that the final gel was transferred to a poly propylene bottle and heated in an oven at 95oc overnight. precipitation occurred until a clear solution was observed indicting complete crystallization. the bottle was opened and left to cool then the wet solid product was set to filtration, washing with distilled water several times until the ph of the filtrate was 9. the product was dried at 110 oc for 24 hr. and then calcined at 500oc at a rate of 2 oc /min. for 3 hr. ion exchange step the acid form of zeolite y was obtained by ion exchange with a solution of ammonium chloride nh4cl using two concentrations ( 2 and 4 n) at 70oc. 10 g of zeolite nay was slurried in 200 ml of ammonium chloride solutions with mixing at 70oc for 2 hr and then left at room temperature overnight. after that the exchanged zeolite was filtered off ,washed with deionized water, dried at 110oc overnight, and then calcined at 525oc for 3 hr.[12]. the prepared zeolite were characterized by different techniques and compared with commercial type. these techniques include (xrd), (ftir), (bet), (tga), (sem), (afm) and (nh3-tpd). the xrd for powder product were measured using philips diffractometer with cu target at 2 theta value from 10 to 60 o. the particle size and morphology were analyzed using sem at different magnification by oxford instrument. the ir spectra was analyzed using perkin ftir in the wavelength range of 400 – 4000 cm-1. with kbr pellet method. bet surface area and pore volume were performed using a micrometrics asap 2020,the sample were degassed for 2 hr under vacuum at 250oc .afm was performed using scanning probe microscope (spm), tga test using shimadsu tga-51 thermo-gravimetric analyzer and nh3-tpd was obtained using micromeritics auto chem ii chemisorption analyzer. 3. results and discussion 3.1. xrd the powder diffraction patterns of zeolite samples were scanned using xrd diffract meter in the 2 theta range between 5 -60 degree at scanning speed of 5 deg / min using cu-kα radiation source of wave length λ=1.5406 aº. the formation of zeolite y phase was confirmed by comparing the diffract grams of all synthesized samples to the diffract grams of the reference zeolite y[10]. comparison indicates that the preparation method results is compatible with crystal structure of y zeolite to conclude that the preparation nada s. ahmedzeki al-khwarizmi engineering journal, vol. 12, no. 1, p.p.79 89 (2016) 81 method gives a good synthesized indigenousness of y zeolite [13]. the size of crystallites was correlated using scherrer eq.1 …(1) where d is the diameter of crystallite , λ is the xray wave length ,β is the broadening line at the half maximum intensity which represent the full width at half maximum (fwhm) and θ is the bragg angle at which the scattering wave was reflected or scattered at lattice plane producing intense peaks. the average diameter of crystallite is 29.6 nm for prepared zeolite while for reference is 18nm. all peaks observed can be assigned to y zeolite structure characterized by 2θ of standard type equals to 6.3, 15.8 &23.7 degree as shown in table.1 and 2. table 1, xrd data of synthesized zeolite nay. table 2, xrd data of reference zeolite nay. 3.1.1 aging time the effect of aging time on zeolite formation was investigated and the xrd patterns of prepared samples were shown in fig.2and the crystallinity was calculated using eq.2 by considering the ratio of the sum of intensities of 10 major peaks [14,15]. the results showed that 48 hr aging time was preferred in comparison to other aging time of 24, and 72 hr giving higher crystallinity of about 82% while for other samples was 75% and 52% as shown in fig.1. …(2) fig. 1. crystallinity % of the prepared zeolite. fig. 2. xrd pattern of synthesis nay zeolite at different aging time (a. 24 hr. , b. 48 hr., c. 72 hr.), x-axis 2theta,y-axis intensity . synthesized zeolite 2θ і / іо intensity fwhm degree 6.344 100 0.327 15.97 75 0.247 23.61 84 0.9162 reference zeolite 2θ і / іо intensity fwhm degree 6.181 100 0.501 15.518 78.7 0.398 23.478 83.1 0.589 ��������� ��� % = ∑ і ������ ∑ і ����� �� ∗ ��� a b c nada s. ahmedzeki al-khwarizmi engineering journal, vol. 12, no. 1, p.p.79 89 (2016) 82 3.2. surface area and pore volume nitrogen adsorption –desorption were carried out using micromeritics asap 2020 instrument to determine the bet (brunaure emmett teller) surface area and pore volume. after degassing the isotherms is investigated at relative pressure p/po from 0 to 1. surface area and pore volume are also measured. bet surface area is calculated according to this equation: …(3) where sa : surface area m2 /gm, vm : volume of monolayer m3, am : area occupied by one molecular of nitrogen in monolayer is 0.162 nm2, n: avogadro's number 6.02*1023 molecules /mole. it can be seen from the isotherms in fig. 3 that the sample exhibited behavior of type two according to the classification of bet and this type shows large deviation from langmuir model of adsorption and the intermediate flat region in the isotherm correspond to the formation of monolayer formation and best surface area and pore volume were obtained at aging time of 48 hr as shown in table 3. fig. 3. (a) adsorption isotherm of prepared y zeolite at aging time 48hr, (b) bet plot. table 3, surface area and pore volume of prepared zeolite. aging time hr bet surface area m2/gm langmuir surface area m2/gm pore volume m3/gm 24 201.9 286.63 0.213 48 499.43 707.95 0.38 72 210.6 298.79 0.209 3.3. xrf xrf was used to determine the chemical composition and structural formula of prepared samples were determined ,and si/al ratio was also calculated from the results of this analysis as shown in table 4. table 4, chemical composition and silica to alumina ratio of prepared zeolite. 3.4. ion exchange the exchanged technique was used in this process is one step batch impregnation under a constant temperature and different normality to convert nay zeolite in to hy . fig.4 shows the mechanism of ion exchange. fig. 4. ion-exchange of na-form of zeolite y into hform zeolite. zeolite is normally hydrophilic especially for small si /al ratio, the number of free cations is high so it is favored to increase the si/ al ratio by ion exchange. the number of cations able to interacts with water decreases and the absorption of non-polar compounds molecular such as hydrocarbons leads aging time hr 24 48 72 sio2 wt.% 63.86 59.17 64.63 al 2o3 wt.% 22.32 20.10 23.83 na2o wt.% 8.966 9.30 7.208 sio2 /al2o3 molar ratio 4.86 5.004 4.61 a b nh4cl nada s. ahmedzeki al-khwarizmi engineering journal, vol. 12, no. 1, p.p.79 89 (2016) 83 to use these zeolite as a catalyst in many petroleum processes such as cracking or reforming. the percentage of the ion exchange, silica to alumina ratio and the concentration of sodium ion before and after protonation are listed in table.5. table 5, chemical composition of modified zeolite. 3.5. ftir the chemistry of the surface of catalyst including surface acidity was measured using infrared technique. faujasite structure is characterized by the functional groups and regions found in fig. 5 the bands that appear in the region between 3365-3489 cm-1 reveal to the oh stretching band in the sodalite cage which belongs to the bronstest acid protons, also called low frequency band ,sio4 molecules and al-oh .the bands in the range of 10101019 cm-1 indicate the presence of si-o, assigned to external asymmetrical stretching while the band at about 600 cm-1 is assigned to the internal tetrahedral symmetrical stretching . the peak in about 1600 cm-1 corresponds to the bending vibration of water molecules in the zeolite structure. absorption at about 443 -465 cm-1 was assigned to si – o – al stretching where al is in the octahedral coordination. therefore, it was concluded that the ftir spectra of the synthesis zeolite matches the typical absorption peaks of commercial type[16,17,18] . 3.6. tga thermal analysis is performed for the synthesized samples of zeolite nay, hy and commercial type. thermogravimetric plots are shown in fig.6. it can be interpreted that as the temperature increases (30-200 oc), there was a little weight loss from the samples due to the water evaporation and dehydration. the same trend was found for the three samples. this give an indication of the validity of the calcination temperature ,also after the ion exchange step using nh4cl. the percentage of weight loss of the physically adsorbed water for synthesized nay and hy zeolite are 22.92% and 18.72 respectively while for commercial zeolite is 23.9% which is in agreement of the results in references of published studies [19, 20]. fig. 5. ftir of synthesized zeolite y at different aging time, (a)24hr, (b)48 hr, (c)72hr and (d) hy zeolite . weight percent ,wt.% before 2 n 4n na2o 9.30 3.58 1.954 sio2 20.10 54.84 57.96 al 2o3 59.17 17.86 19.01 sio2 / al2o3 molar ratio 5.004 5.22 5.183 % ion exchange 61.50 78.98 40060080010001200140016001800200024002800320036004000 1/cm -0 10 20 30 40 50 60 70 80 %t ftir measurement b 40060080010001200140016001800200024002800320036004000 1/cm 7.5 15 22.5 30 37.5 45 52.5 60 67.5 75 %t 3 6 2 9 .2 2 3 6 0 8 .0 1 3 5 9 5 .4 7 3 5 8 7 .7 5 3 5 6 7 .5 0 3 5 5 3 .0 3 3 5 4 7 .2 4 3 5 3 7 .6 0 3 5 2 7 .9 6 3 5 1 9 .2 8 3 5 1 0 .6 0 3 4 8 2 .6 3 3 4 7 2 .0 2 3 4 6 2 .3 7 3 4 4 4 .0 5 3 4 3 2 .4 8 3 4 2 2 .8 3 3 4 1 8 .0 1 3 4 0 6 .4 4 3 3 8 8 .1 1 3 3 7 8 .4 7 3 3 6 4 .0 0 3 3 5 8 .2 1 3 3 4 7 .6 0 3 3 3 5 .0 7 3 3 2 2 .5 3 3 3 0 2 .2 7 1 0 2 0 .3 9 1 0 1 0 .7 4 1 0 0 1 .1 0 9 9 3 .3 8 4 5 9 .0 8 4 4 6 .5 4 4 3 8 .8 2 ftir measurement a 40060080010001200140016001800200024002800320036004000 1/cm -0 7.5 15 22.5 30 37.5 45 52.5 60 67.5 75 %t 3 5 8 7 .7 5 3 5 6 6 .5 3 3 5 2 7 .9 6 3 5 0 9 .6 3 3 4 9 0 .3 4 3 4 8 3 .5 9 3 4 4 5 .0 1 3 4 4 0 .1 9 3 4 3 1 .5 1 3 4 2 3 .8 0 3 4 1 8 .9 7 3 4 0 6 .4 4 3 3 9 6 .7 9 3 3 8 8 .1 1 3 3 7 9 .4 3 3 3 5 6 .2 8 3 3 4 9 .5 3 3 3 3 9 .8 9 3 2 8 4 .9 1 3 2 6 6 .5 9 3 2 2 7 .0 5 1 6 3 6 .6 7 1 0 4 6 .4 3 1 0 4 0 .6 4 1 0 2 9 .0 7 1 0 0 8 .8 1 9 9 4 .3 5 9 8 9 .5 3 9 8 5 .6 7 9 7 3 .1 3 7 7 4 .4 5 7 7 0 .6 0 7 5 9 .9 9 6 9 5 .3 7 6 3 2 .6 8 5 6 7 .1 0 5 4 4 .9 1 4 8 9 .9 4 4 7 2 .5 8 4 6 4 .8 6 4 5 8 .1 1 4 5 3 .2 9 4 5 0 .4 0 ftir measurement d 40060080010001200140016001800200024002800320036004000 1/cm -0 7.5 15 22.5 30 37.5 45 52.5 60 67.5 75 %t 3 6 47 .5 5 36 2 9 .2 2 3 60 8 .0 1 3 5 9 5. 47 3 58 7 .7 5 3 5 6 7. 5 0 35 4 8 .2 1 3 52 7 .9 6 35 0 9 .6 3 3 49 0 .3 4 3 48 2 .6 3 34 7 3 .9 5 3 46 2 .3 7 3 44 1 .1 6 3 4 22 .8 3 34 1 8 .0 1 3 4 06 .4 4 3 39 2 .9 3 33 8 3. 2 9 33 7 4 .6 1 33 6 3 .0 3 33 5 9 .1 8 3 3 4 9. 5 3 3 32 3 .4 9 33 0 1 .3 1 3 2 86 .8 4 3 26 6 .5 9 32 4 8. 2 7 3 24 2 .4 8 3 2 31 .8 7 1 0 1 7. 4 9 1 0 0 6. 8 9 99 6 .2 8 9 8 9. 53 45 5 .2 2 4 31 .1 1 4 18 .5 7 ftir measurement c nada s. ahmedzeki al-khwarizmi engineering journal, vol. 12, no. 1, p.p.79 89 (2016) 84 fig. 6. tga of zeolite y, (a) synthesized nay, (b) synthesized hy,(c) commercial hy. 3.7. sem and afm na-y zeolite crystal size and morphology were observed by sem. results show the cubic crystalline micrographs of the synthesized zeolite having small average size of nano sized particles as compared with commercial type and the images show a good agreement with that shown in literature which reveals a uniform particle size with regular shape[11,13,14]. to investigate the surface uniformity afm technique is used. by comparing the surface of synthesized and commercial zeolite there is no change in surface roughness as shown in fig.9. it depicts a uniform nano and micro structure and highly crystalline material with uniform pores. the average particles size of the prepared zeolite is 80 nm and for exchanged is 71nm while for commercial type is about 91nm. [21],[22]. fig. 7. sem images of synthesized zeolite y, (a)25 000 x, (b) 50 000 x. fig. 8. sem images of commercial zeolite y, (a)25 000 x, (b) 50 000 x. 3.8. tpd temperature programmed desorption of ammonia (nh3-tpd) is used to determine the acidity of prepared zeolite samples. all samples are heated up according to steps shown in figs. 10-13 and the thermal conductivity detector (tcd) is recorded. data obtained is utilized and c a b a b b a nada s. ahmedzeki al-khwarizmi engineering journal, vol. 12, no. 1, p.p.79 89 (2016) 85 plotted by calculating the area under the peaks shown in these graphs. zeolite acid sites are characterized using nh3tpd ,total amount of acidity and acid distribution are obtained from peaks area ,position and shape. although nh3-tpd giving an information about the strength of acid site but it cannot distinguish between acids site types as bronsted or lewis. figs.10-13 show nh3-tpd spectra of prepared ,modified and commercial zeolite and all profiles of the sample represent the low peak while for modified samples high peak are also appear and are noticeable than y zeolite this because of protonation effect . the results obtained are in agreement with that in literature as the low peak appears at a temperature of about 200 oc and intermediate appears between 350 – 350 oc while the high acidity peak represented at temperature between 500 -600 oc, sometimes it doesn't appears purely because its overlapped or engaged with other peaks. acidity peak represented at temperature between 500 -600 oc, sometimes it doesn't appears purely because its overlapped or engaged with other peaks. the high temperature peak can be attributed to the desorption of ammonia from both strong bronsted and lewis acid site and on the other hand the low temperature peak can be related to a number of causes such as the adsorption of ammonia on weakly acid site as bronsted and lewis, silanol groups and formation of nh+ 4groups.[ 23, 24, 25 ]. fig. 9. particle size distribution and 3-d dimensional images. (a) synthesized zeolite y (b) ion exchanged zeolite hy (c) commercial zeolite. b a c nada s. ahmedzeki al-khwarizmi engineering journal, vol. 12, no. 1, p.p.79 89 (2016) 86 fig. 10. nh3-tpd of prepared nay zeolite. fig. 11. nh3-tpd of modified hy zeolite, 2n. fig. 12. nh3-tpd of modified hy zeolite, 4n. fig. 13. nh3-tpd of commercial hy zeolite. nada s. ahmedzeki al-khwarizmi engineering journal, vol. 12, no. 1, p.p.79 89 (2016) 87 4. conclusion nano crystalline na-y zeolite has been prepared successfully using sol-gel method under hydrothermal condition. the decrease in crystal size affects the physical properties of the product such as surface area and surface uniformity as compared with microcrystalline type. nano crystalline zeolite nay and hy are prepared and characterized using different methods. results showed well defined morphology, uniform distribution, high surface area, and stable structure. acknowledgment the authors are gratefully acknowledging the iraqi ministry of higher education for the financial support. also, the authors thank the izmir institute of technology in turkey and the petroleum research and development center (prdc)-ministry of oil in iraq for implementing the characterization analysis. 5. references [1] mohammed r., rahimpour m. and davood i., "progress in catalytic naphtha reforming process: a review" applied energy, 109, (79 – 93), 2013. 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" zeolites by confined space synthesis – characterization of the acid sites in nanosized zsm-5 by ammonia desorption and al/si nmr spectroscopy" microporous and mesoporous materials, 39, (393 -401), 2000. [8] chester a.w. and derouane e. g., zeolite characterization and catalysis. a tutorial, springer, 2009. [9] sadeghi m, sharifi s.l., hatami h., synthesis of nanocrystalline zeolite nay by hydrothermal method and investigation of its structure and morphology, int. j.nano dimens. 5(1): 91-95, 2014 . [10] rahman m., awang m. and yuof a. ," preparation ,characterization and application of zeolite y for water filteration" australian journal of basic applied science , 6 , ( 50 – 54), 2012. [11] nik a. and alias m. ," removal of cr(iii) fom aqueous solutions using zeolite nay prepared from rice husk ash" the malaysian journal of analytical science , (11 ), (76 – 83), 2007. 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[16] kavan m., " template –free synthesis and modification of lty,zsm-5 and ltl zeolite catalysts and investigation of catalytic pyrolysiss of saskatchewan boundary dam coal" msc. thesis ,university gal gary,2013. [17] niken t., abdual rahman m. and subhash b. ," nanocrystalline zeolite y : synthesis and characterization " iop conf. : material science and engineering., 17,2011. [18] yaneri p. and petit d.," linde type a zeolite and type y faujasite as a solidphase for lead, cadmium, nickel and cobalt preconcentration and determination using a flow injection system coupled to flame atomic absorption spectrometry " american journal of analytical chemistry, 4, ( 8-14), 2013. [19] hilal g. ," liquid phase hydrogenation of citral on zeolite supported monometallic (ni,pt) and bimetallic (ni, sn), (pt-sn) catalysts" msc thesis , izmir institute of technology, 2005. [20] emre k., " an investigation of activities and selectivites of hzsm-5 and h-ferrite zeolite modified by different method in n-butene isomarization" msc. thesis, izmir institute of technology, 2010. [21] atheel h., ahmed z. and norli s. ," investigation on the catalytic behavior of fe loaded on encapsulated titanium for sonocatalytic degradation of amaranth :characterization and reusability study" modern research in catalysis, 2, (100 109), 2013. [22] nabiollah m., navid r. and homayon a.," porosity ,characterization and structural properties of natural zeolite–clinoptiloliteas a sorpent", environment protection engineering , 39, (139-151), 2013. [23] conghua l., xionghou g., and zhongdon z., " surface modification of zeolite y and mechanism for reducing naphtha olefin formation in ctalytic cracking reaction" applied catalysis , 264, (225-228), 2004. [24] atchariya a. , kongkiate s., and sirachay k." effect of catalyst acidity on thermal cracking of ethylene at high temperature and pressure" international conference on chemical , civil and environmental engineering ,nov. 2014, singapore. [25] tonetto g., atias j. and de lasa h. ," fcc catalysts with different zeolite crystalline sizes: acidity ,structural properties and reactivity" applied catalysis , 270 ,( 9-25), 2004. )2016( 7989، ! �� 1، ا���د����12 ا���ارزم� ا������� ا� ��م ��ى ���ون ا � ز�� 89 ذو ا�.)��ا�,��ري ا��+��ي na–y'�(�) و'&��% ز#�$#" *** ا � 5+ن 4,� ا�) 1 **!3ح ا��#1 #� 0 * ا � ز�� ��ى ���ون ���� ا������و�� *�� ا�� /����� )�'&� %$�اد / "!�� ا� ���� ا������و��**�� ا�� / ��()!��� از'�+ �!*�&'/ ��"+ ***./0� %$�اد /وزارة ا��50 /'+"4 ا�123 وا�*/(�+ ا� �!3� ا� �� '�e�3/fت '!2(ظ� b .c*? ا��;�<ت ي�ر ا�&��� ا�? ا��4(<�= ذ-*;: ا89� ��� ����!e*ا<9(اع ا� h2' h2*� 9(ي��c. ھkه . ا�*+"�i ا�3!(ري وا� ء -� ا)+ا. ز�(<�= hy%�&�'!� ا�;h ا�3!(ري r+ار�� و-� ا)+اء �n!�� ا�*�3دل ا<�(p2!� .9(ل na-y ?!nا��را�� -� -�m2+ ز�(<�= 9(ع �+ ا�e(ة ا�kر�� وا��;�+ &� c(ق ا��2+اء و-x�uv ا<%&�د %*h�!2 ا�(ز9. ا�2+اري وا��/��ف ذو ا<ht' ��p�uv*�b ا<b&� ا������ وا�ا��s)20ت ا;� ��9)'z� ا<'*4از [�n ��!�&� در)� ا�2+ارة h�!2-و f�(و+*��*hn�0 و9��3 ا��!��� ا�? -� درا�� -�\�+ ز'f ا. ا<��*+و9. وا�����r ا��/��2 %�<'*4از %�� ���� c. ا�p2(ل i�"+?!n '��'. %!(ري %��eس . ا<�('�r�;9و +�m2*ا� ��!�n ����&c ^_�*��/ ٢'*+ 9�9٤٩٩('*+ و'���r �/��2 ٨١و ٧٠ا\3= ا�g . 100109 al-khwarizmi engineering journal,vol. 12, no. 1, p.p. optimization of friction stir welding process parameters dissimilar aa2024-t3 and aa7075 muna k. abbass *,**,***department of production engineering and metallurgy/ university of technology (received abstract the aim of present study is to determine the optimum parameters of friction stir welding process and most important parameter along with percentage contribution of each parameter joint efficiency of fs welded joint of dissimilar aluminum alloys aa2024 by applied specific number of experiments using taguchi method .aa2024 was placed on the advancing side and aa7075 on the retreating side. fsw was three different welding speeds (20, 45 and 69) and cone) and tool tilt angle 2◦. taguchi process parameters and the three levels of variation for each pa design were applied to the results. the result of s\n ratio analysis were obtained to find the parameters optimization, which has been of rotation speed equal to 898 rpm, welding speed 45 mm tensile strength result shows that the welding speed was the most 66.05 % over the other process parameters. keywords: friction stir welding, aluminum 1. introduction friction stir welding (fsw) is a state welding processes that was invented involves a cylindrical shoulder tool with a profiled pin which is rotated and thrust quickly into the joined between two pieces of plate or to keep joint faces from separated they securely clamped [2]. frictional hea between welding tool and the work pieces material. this heat resulting the work pieces to soften but it doesn’t reach to melting and permits the tool to move along the weld line.the resultant material which has become plasticized is moved from the leading edge to the trailing edge of the tool pin and is forged together khwarizmi engineering journal,vol. 12, no. 1, p.p. 100109 (2016) friction stir welding process parameters t3 and aa7075-t73 aluminum alloy taguchi method muna k. abbass* munthir m. al-kubaisy ruqaya abdulkadhim*** department of production engineering and metallurgy/ university of technology *email: mukeab2014@yahoo.com **email: drmnthr_mm@yahoo.com ***email: rukaia1990@yahoo.com (received 18 december 2014; accepted 28 june 2015) the aim of present study is to determine the optimum parameters of friction stir welding process and parameter along with percentage contribution of each parameter which effect joint of dissimilar aluminum alloys aa2024-t3 and aa7075 specific number of experiments using taguchi method .aa2024 was placed on the advancing side and was achieved under three different rotation speeds (898, 45 and 69) mm\min , three different pin profiles (cylindrical, threaded cylindrical taguchi method was proposed the orthogonal array of l9 based on the three number of process parameters and the three levels of variation for each parameter , s\n ratio and anova analysis of robust n ratio analysis were obtained to find the parameters optimization, which has been of rotation speed equal to 898 rpm, welding speed 45 mm\min, and threaded cylindrical pin profile with joint efficiency (76%). that the welding speed was the most important parameter with a percentage contribution of 66.05 % over the other process parameters. , aluminum alloys, taguchi method. friction stir welding (fsw) is a modern solid processes that was invented [1]. it a cylindrical shoulder tool with a profiled pin into the area to be or sheet material. to keep joint faces from separated they have to be frictional heat is produced between welding tool and the work pieces of the work pieces to be to melting temperature along the weld which has become from the leading edge to the trailing edge of the tool pin and is forged together by close contact of the tool shoulder and pin profile. thus creating bond between [3]. many industries such as aerospace, ship building, automobile have adopted welding in their welding operations. this because many advantages over traditional welding methods. among these advantages are it does not cause much distortion, fume, porosity or spatter, consumables (wire used as a filler). moreover, it does not need surface treatment and shielding gas [4]. the taguchi method has been large scale to engineering analysis and used in designing systems with high quality taguchi method, using orthogonal array to investigate the al-khwarizmi engineering journal (2016) friction stir welding process parameters of alloys by using kubaisy** department of production engineering and metallurgy/ university of technology the aim of present study is to determine the optimum parameters of friction stir welding process and known the which effect on tensile strength and and aa7075-t73 of 3 mm thick plates specific number of experiments using taguchi method .aa2024 was placed on the advancing side and under three different rotation speeds (898, 1200 and 1710) rpm, (cylindrical, threaded cylindrical orthogonal array of l9 based on the three number of n ratio and anova analysis of robust n ratio analysis were obtained to find the parameters optimization, which has been of rotation speed d cylindrical pin profile with joint efficiency (76%). the parameter with a percentage contribution of contact of the tool shoulder and pin thus creating bond between work pieces ]. many industries such as aerospace, ship building, automobile have adopted friction stir welding in their welding operations. this because many advantages over traditional welding methods. among these advantages are it does not cause much distortion, fume, porosity or spatter, consumables (wire used as a filler). moreover, it s not need surface treatment and shielding gas the taguchi method has been applied in a engineering analysis and is widely used in designing systems with high quality. a special design of orthogonal array to investigate the influence of the muna k. abbass al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 100109 (2016) 101 entire welding parameters through the small number of experiments [5], thus bringing out the most important factors in the process by employing variance analysis (anova) and signal-to-noise ratio (s/n)". palanivel and mathews [6] focused on the tensile behavior of dissimilar joints of aa6351t6 and aa5083-h111 of 6mm thickness produced by friction stir welding . five various of tool pin, like straight square, tapered square, straight hexagon, straight octagon and tapered octagon, with three various welding speeds of 50, 63 and 75mm/min , and speeds of tool rotational of 950 rpm have been used to weld the joints. they found that the straight square pin with 63 mm/min produced tensile strength higher than that of the other tool pin profiles and welding speeds. kumbhar and bhanumurthy [7] described the microstructural development and mechanical properties which are associated with the dissimilar joints of friction stir welding of aluminum alloys aa5052 and aa6061 of 5mm thickness . friction stir welding was performed at different combinations of speeds of tool rotation of 1120 and 1400 rpm and welding speeds of 60, 80 and 100 mm\min and 3◦ tilt angle of the tool. the tensile test specimens evaluation showed good mechanical properties. the alloying elements interdiffusion and similar orientations development in the nugget zone could help produce the better tensile properties of the friction-stir-welded of specimens of aa5052aa6061. many researchers [8, 9] studied the effect of friction stir welding parameters such as welding speed , speed tool rotational and types of tool pin profile on the microstructural and mechanical properties of dissimilar aluminum alloys aa7075 and aa6061. they found that the tensile strength of the dissimilar joints increases with increasing welding speed and tool rotation speed. rajamanickam and balusamy[10] described the effect of friction stir welding parameters on mechanical properties of 2014 aluminum alloy plate using design of experiments doe . with 9 experiments, varying process parameters like speed of tool rotation and speed of welding were taken in consideration . anova was used to examine the influence of input parameters on mechanical properties of joints which were welded .the tensile strength, hardness and elongation were used to characterize the samples. it was concluded that increase in speed of welding is proportional to the tensile strength. the sample which was welded with speed of rotation of 1200 rpm and speed of welding of 8mm/min showed the highest elongation, on the other hand the sample welded with the 600rpm and 20 mm/min showed lowest elongation. suresha et al. [11] studied the effect of parameters of friction stir welding process on tensile strength and efficiency of fsw joints for two kinds of tool pin profiles namely conical and cylindrical tool heads with grooves. the process parameters of friction stir welding include speed of tool rotation of 900, 1120 and 1400 rpm, speed of welding of 40, 50 and 63 mm\min and depth of plunge of 4.93, 4.96 and 4.99 mm. it has been noted that the speed tool rotational shows more effect on tensile strength in both tools. better joint efficiency comes from conical profile than from the cylindrical profile tool. anova was used to determine the percentage contribution of these parameters of the process and it was concluded that the speed of tool rotational and speed of welding are the important parameters which contribute to the response. krishna et al. [12] used the taguchi experimental design technique to determine the optimum welding parameters for friction stir welds of different alloys of aluminum "aa2024t6 and aa6351-t6" for tensile properties. the effect of fsw parameters, speed of rotation, speed of welding and axial force, on tensile strength was evaluated. so as to enhance the productivity and weld quality, best welding conditions to get the highest stensile strength were assessed. a mathematical model based on nonlinear regression was developed to establish the relation between the parameters of process and tensile strength. the confirmation tests were made to confirm the results were under the best identified conditions. the current study aims to obtaining the best parameters of fsw welding which are speed of tool rotation, speed of welding and pin geometry. the identification of the most effective parameters of welding process is made by using l9 taguchi orthogonal array. furthermore, anova is used to find out how much each parameter contributes to the process. muna k. abbass al 2. experiment work 2.1. material selection aluminum alloy plates aa2024 aa7075-t73 have been selected to be joined by friction stir welding process due to their wide applications such as aerospace industry, table 1, chemical composition for aa2024-t3 element wt% si fe cu mn 2024 0.126 0.280 4.37 0.593 7075 0.0539 0.296 1.64 0.0105 table 2, mechanical properties of 2024-t3 &7075 alloy yield strength ys(mpa) tensile strength ts(mpa) 2024-t3 345 450 7075-t73 380 455 2.2. tools features the friction stir welding experiment has been carried out using tool made from tool steel type x12m, manufactured in (general foundation for mechanical industry/aleskandria). welding tools are designed and machined as shown in figure 1 and table 3. t subjected to heat treatment (hardening and tempering) and the each tool has average hardness value of 53-55hrc. fig. 1. tool design (a) cylindrical cy (b) threaded cylindrical tc (c) cone c. al-khwarizmi engineering journal, vol. 12, no. 102 aluminum alloy plates aa2024-t3 and selected to be joined by friction stir welding process due to their wide aerospace industry, automotive, building and architecture, etc. plates were cut by punch cutter to the dimensions of (150×70×3) mm. the chemical these alloys was carried out analysis instrument in the general company for examination and rehabilitation engineering, as shown in table1. mechanical properties of these alloys were shown in table 3 and aa7075-t73. mn mg cr ni zn ti pb 0.593 1.27 0.0133 0.0099 0.166 0.0167 0.008 0.0105 2.12 0.183 0.0022 5.56 0.020 0.008 &7075-t73. % elongation hardness hv (500)g temper 22 137 t3:solution heat treatment followed by cold work 16 155 t73: solution heat treatment and then overaged\stabilized the friction stir welding experiment has been tool made from tool steel type x12m, manufactured in (general foundation for eskandria). three welding tools are designed and machined as the tools were subjected to heat treatment (hardening and tool has average hardness fig. 1. tool design (a) cylindrical cy (b) threaded table 3, the welding tools design and details. , no. 1, p.p. 100109 (2016) automotive, building and architecture, etc. these plates were cut by punch cutter to the dimensions the chemical composition of carried out by using spectrometer analysis instrument in the general company for examination and rehabilitation engineering, as mechanical properties of these alloys were shown in table 2. pb v al 0.008 0.0105 bal 0.008 0.008 bal treatment followed by solution heat treatment and then stabilized the welding tools design and details. muna k. abbass al 2.3. friction stir welding process fsw process was carried out by using machine (type: knuth werkzeugmaschinen gmbh, germany) to fabricate butt welded joints. 2.4. orthogonal array selection the experimental design suggested by anova covers the use of orthogonal arrays to arrange in order the parameters of welding process and the levels at which they must differ. in terms of the l9 orthogonal array suggested by taguchi, three experiments were carried out on each set of parameters of process parameters which were used in this experiment were the speed of rotation (rpm), speed of welding and geometry of pin. table 4 shows the parameters and the levels of the process. the tilt angle (2º) remains constant. a total of nine experimental runs were made, a combination of levels was used for each control factor as given in table 5. table 4, parameters and their levels of fsw. parameters level 1 level 2 rotation speed rs (rpm) 898 1200 welding speed ws(mm\min) 20 45 pin geometry pg cylindrical (cy) threaded cylindrical (tc) 1-plunging step al-khwarizmi engineering journal, vol. 12, no. 103 friction stir welding process fsw process was carried out by using milling (type: knuth werkzeugmaschinen gmbh, germany) to fabricate butt welded joints. for all the dissimilar joints, 2024 plates were placed on the advancing side and 7075 was on the retreating side of the weld. stir welding steps. fig. 2. friction stir welding steps. orthogonal array selection design suggested by anova covers the use of orthogonal arrays to arrange in order the parameters of welding process and the levels at which they must differ. in terms of the l9 orthogonal array suggested by taguchi, three experiments were carried out on process. the three parameters which were used in this experiment were the speed of rotation (rpm), speed of welding and geometry of pin. table 4 shows the parameters and the levels of the process. the tilt t. a total of nine experimental runs were made, a combination of levels was used for each control factor as given in table 5, experimental of l9 orthogonal array. 2.5. tensile test transverse tensile tests were performed in order to estimate the tensile properties of fsw joints at all welding parameters. specimens were cut and machined using cnc milling machine type (c-tek) from the welds in direction perpendicular to the welding direction, with geometry in accordance with the specifications given in the astm standard 09 for sub-size specimens as shown in figure 3 [13]. level 2 level 3 1710 69 threaded cylindrical cone (c) experiment no. rs (rpm) 1 898 2 898 3 898 4 1200 5 1200 6 1200 7 1710 8 1710 9 1710 plunging step 2stirring step 3retracting step , no. 1, p.p. 100109 (2016) for all the dissimilar joints, 2024 plates were placed on the advancing side and 7075 was on the retreating side of the weld. figure 2 shows friction experimental of l9 orthogonal array. transverse tensile tests were performed in order to estimate the tensile properties of fsw joints at all welding parameters. tensile specimens were cut and machined using cnc tek) from the welds in perpendicular to the welding direction, with geometry in accordance with the the astm standard e8msize specimens as shown in figure 3 ws (mm\mim) pg 20 cy 45 tc 69 c 20 tc 45 c 69 cy 20 c 45 cy 69 tc retracting step muna k. abbass al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 100109 (2016) 104 fig. 3. astme8m sub-size sample for tensile test, all dimensions are mm [13]. 2.6. microstructure inspection and microhardness test optical microscope was used to examine the samples which were made from a cross section of the fsw joints and base alloy in sequences steps. 1the operation of wet grinding was made using water and emery paper of sic in various grits of 320, 500, 600, 800, 1000 and 1200. 2the process of polishing was made on the samples using 0.5µm diamond paste and special cloth for polishing and lubricant. 3the process of etching was carried out on the samples by using etching solution killer's reagent (composition : 95ml h2o , 2.5ml hno3, 1.5ml hcl, 1.0ml hf) [14]. they were washed and dried. 4 optical microscope is used to provide information about the microstructure of welded samples. 5digital microhardness tester type (laryee, mode hvs-1000) was used to conduct the vickers hardness test. a 500g load was applied to the welded joint cross section for 15 sec. 3. results and discussion 3.1. signal to noise ratio: (s\n) ratio tensile strength is an important response characteristic taken into consideration in this investigation. it describes the quality of fsw welded joints. so as to estimate the effect of welding parameters on tensile strength, means and s/n ratio for each control factor (speed of tool rotation, the speed, of welding and pin geometry) were calculated. the appropriate s/n ratio was selected using previous knowledge, experience, and process understanding. in this study, the s/n ratio was selected in terms of the standard of the “higher is better”, in order to maximize the response. in the taguchi method, is used to determining the difference of the quality characteristics from the value desired is achieved by using the s/n ratio. in this study, the tensile strength data were analyzed to decide the influence of fsw parameters. table 6 shows the three levels of parameters of process as per l9 orthogonal array, the means of tensile strength and corresponding s/n ratio. analyzing the mean for each of the experiments will result in better parameter combination level so that tensile strength at high level is made certain in terms of experimental data. the plots as in figures (4and5) can be used to identify the highest level of process parameter conformity to the highest s/n ratio and tensile strength respectively.the tensile strength is assessed to be the highest with speed of rotation of 898 rpm and speed of welding of 45mm/min and threaded cylindrical pin geometry (tc) which is optimal from the plots obtained. table 6, tensile strength, joint efficiency and s/n ratio for experiments. experiment no. rs (rpm) ws (mm\min) pg mean mpa efficiency% s\n ratio 1 898 20 cy 318 71 50.05 2 898 45 tc 340 76 50.62 3 898 69 c 300 67 49.54 4 1200 20 tc 327 73 50.29 5 1200 45 c 315 70 49.96 6 1200 69 cy 310 69 49.82 7 1710 20 c 311 69.1 49.85 8 1710 45 cy 330 73.3 50.37 9 1710 69 tc 295 66 49.39 muna k. abbass al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 100109 (2016) 105 fig. 4. main effect plot for s/n ratio. fig. 5. main effect plot for mean tensile strength. 3.2. analysis of variance (anova) the anova test is used to examine the importance of the parameters of welding process which influence the tensile strength of joints welded with fsw. the f-test named after fisher can also be utilized to determine which process has important influence on tensile strength. usually, the difference of the process parameter has a significant influence on the quality characteristics of tensile strength of welded joints , when f is high .the anova test results show that the process parameters considered are very important factors which influence the tensile strength joints welded with fsw in the order of speed of rotation,speed of welding and geometry of pin. it is shown that the anova of tensile result display that the speed of welding is the most effective parameter having a percentage of 66.05 %, followed by geometry of pin of 15.68% and speed of rotation of 5.21%. as shown in table 7. table 7, anova of tensile strength (means). note: dfdegrees of freedom, seq ss – sequential sum of squares, adj ss –adjusted sum of squares, adj ms – adjusted mean square, , f─fisher ratio. pa percentage contribution. 3.3. tensile test results the tensile strength of all the joints tested were noted to be lower than the tensile strength of the base alloys as shown in figure 6. in welding, the heat input has a great effect on the weldment mechanical properties. from the experimental results, it was found that the tensile strength is directly proportional to increase in speed of welding in the tested range. it was also noted that the tensile strength increases with increase in speed of tool rotation up to 898 rpm and then decreases. in fsw, it is seen that the increase in speed of the welding and decrease in the speed of tool rotation reduce the required heat input for joining which lead to reducing the thickness of thermomchanically affected zone tmaz and haz which in turn enhances the tensile properties. other workers reached the same results[10] . parameters df seq ss adj ss adj ms f pa% rotation speed rs (rpm) 2 86 86 43 0.16 5.21 welding speed ws(mm\min) 2 1093.6 1093.6 546.8 5.84 66.05 pin geometry pg 2 260 260 130 0.56 15.68 muna k. abbass al fig. 6. tensile strength of base alloys and fsw welded joints. from figure 6 it was seen that the increase in the tensile strength is in direct proportion to rotational speed at 898 rpm, after that it reduces . the tensile strength first increases to a maximum value and afterwards show reduce with increasing the rotational speed at a given welding speed or tool pin geometry of the friction stir welded joints. generally the tensile strength is low at lower rotational speeds because of unsuitable tool stirring action but with the increase of rotational speed for a certain range the strain hardening influence induced by tool stirring action increases tensile strength but the tensile strength lowers significantly with an increase of rotational speed to a rather high value due to increase heat input results in reprecipitation, reduction in dislocation density and coarsening of strengthening precipitates. the variation in tensile strength value at various speed of rotational for a tool pin geometry is because of the different of material flow and frictional heat generated. for a given rotational speed or tool pin geometry, the increase of welding speed increases the tensile certain value, and further increase of speed of welding results in the reduce in the tensile strength of the friction stir welded joints at lowest (20 mm/min) and highest speed of welding (69 mm/min) lower tensile strengths are observed. the lower speed of welding, which significantly deteriorates the mechanical properties of joints due to larger heat input into the weld samples, however as the welding speed increases, the thermal cycles effect is minimized which leads to an increase in tensile strength. the lower tensile strength at 69mm/min is due to insufficient frictional heat generated. the dissimilar joints fabricated using the threaded cylindrical (tc) tool has maximum tensile strength than that the joints al-khwarizmi engineering journal, vol. 12, no. 106 fig. 6. tensile strength of base alloys and fsw that the increase in the tensile strength is in direct proportion to nal speed at 898 rpm, after that it reduces . the tensile strength first increases to a maximum value and afterwards show reduce with increasing the rotational speed at a given welding speed or tool pin geometry of the friction stir welded joints. y the tensile strength is low at lower rotational speeds because of unsuitable tool stirring action but with the increase of rotational speed for a certain range the strain hardening influence induced by tool stirring action increases the tensile strength lowers significantly with an increase of rotational speed to a rather high value due to increase heat input results in reprecipitation, reduction in dislocation density and coarsening of strengthening nsile strength value at various speed of rotational for a tool pin geometry is because of the different of material flow and frictional heat generated. for a given rotational speed or tool pin geometry, the increase of welding speed increases the tensile strength to a certain value, and further increase of speed of welding results in the reduce in the tensile strength of the friction stir welded joints at lowest (20 mm/min) and highest speed of welding (69 mm/min) lower tensile strengths are observed. the lower speed of welding, which significantly deteriorates the mechanical properties of joints due to larger heat input into the weld samples, however as the welding speed increases, the thermal cycles effect is minimized which leads to nsile strength. the lower tensile strength at 69mm/min is due to insufficient frictional heat generated. the dissimilar joints fabricated using the threaded cylindrical (tc) tool has maximum tensile strength than that the joints made using other two tools agreement with research[15]. the tensile strength of the base alloys and dissimilar joints at optimal welding parameters shown in figure 7. fig. 7. stress-strain curves of base alloys (aa2024 and aa7075) and as welded sample mm\min and threaded cylindrical pin profile. 3.4. microhardenss results figure 8 shows the profile of microhardness along the fs weld showing a value of 162 hv in the center weld. it can be obseved the hardness of welded joint is lower in the heat affected zone haz as regards both the 2024 and 7075 base alloys. this is related to the classi fsw welded aluminum alloys. two main reasons account for the improved hardness of the stir zone(sz): (1) the sz grain size a lot finer than that of base metal; strengthening of a materials is very much affected by grain refinement becau inversely proportional to grain size decreases. (2) hardness is improved by the fine particles of intermetallic compounds and fine precipitates, because the difference in hardness between the haz and sz is due to the refinement of grain in the sz. the stirred zone has higher hardness compared with the haz and tmaz because of the smaller grain size at this zone. the haz zone experienced thermal cycle without plastic deformation, the over-ageing and coarsening of strengthening precipitates reduced the hardness in haz. the over-ageing of precipitates in the haz depends on the heat exposure time and temperature, and it controlled by rotational and welding speeds and also the deciding factors for the hardness distribution in haz similar results wer elsewhere [15]. , no. 1, p.p. 100109 (2016) made using other two tools these result are in agreement with research[15]. the tensile strength of the base alloys and dissimilar joints at optimal welding parameters is strain curves of base alloys (aa2024 and aa7075) and as welded sample at 898 rpm, 45 min and threaded cylindrical pin profile. results the profile of microhardness along the fs weld showing a value of 162 hv in the center weld. it can be obseved the hardness of welded joint is lower in the heat affected zone haz as regards both the 2024 and 7075 base alloys. this is related to the classical behavior of fsw welded aluminum alloys. two main reasons account for the improved hardness of the stir (1) the sz grain size a lot finer than that of base metal; strengthening of a materials is very much affected by grain refinement because hardness is inversely proportional to grain size decreases. (2) hardness is improved by the fine particles of intermetallic compounds and fine precipitates, because the difference in hardness between the haz and sz is due to the refinement of grain in the stirred zone has higher hardness compared with the haz and tmaz because of the smaller grain size at this zone. the haz zone experienced thermal cycle without plastic deformation, the ageing and coarsening of strengthening ced the hardness in haz. the ageing of precipitates in the haz depends on the heat exposure time and temperature, and it controlled by rotational and welding speeds and also the deciding factors for the hardness similar results were reported muna k. abbass al fig. 8. microhardness distribution across the transverse cross section of fsw dissimilar al aa2024-t3 and aa7075-t73. 3.5. microstructure results figure 9 shows sample microstructure cross section of joint welded with fsw at best parameters of welding. it is observed that joints welded with fsw do not show any defect and any other imperfection ( for example lack of fig. 9. microstructures of dissimilar fsw aluminum alloys (aa2024 4. conclusions 1the optimum values of parameters of fsw welding like speed of rotational, traverse speed and geometry of pin are 898rpm and cylindrical threaded pin geometry respectively. al-khwarizmi engineering journal, vol. 12, no. 107 microhardness distribution across the transverse cross section of fsw dissimilar al-alloys figure 9 shows sample microstructure cross section of joint welded with fsw at best parameters of welding. it is observed that joints welded with fsw do not show any defect and any other imperfection ( for example lack of penetration, porosity, etc.) due t generation. typical microstructural features of fsw such as the sz, tmaz and haz) have been identified. the parent alloys and haz have similar microstructure. the tmaz region undergoes both heating as well as plastic deformation during fsw because they are characterized by a structure which is deformed and is induced by the tool mechanical stirring . the sz is made by two regions composed of re crystallized very small grains made of both 2024 and 7075 al alloys ,which were composed of grains and equiaxed. the higher temperatures and severe plastic deformations result in remarkable smaller grains than that the parent metal, these results are in agreement with those of researcher [16], in terms of all the fsw literature data for aluminum alloys; the initial elongated grains of the original materials are mechanically changed to a new fine grain structure and equiaxed these results are in agreement with those of researcher [17]. microstructures of dissimilar fsw aluminum alloys (aa2024-t3 and aa7075 the optimum values of parameters of fsw , traverse speed and geometry of pin are 898rpm, 45 mm\min cylindrical threaded pin geometry 2the contribution percentage of fsw process was evaluated, it was found that the speed of welding, speed of rotation and geometry of pin have 66.05%, 5.21% 15.68% contribution respectively obtained from weld 3tensile strength of welded joints increases as the welding speed increases. , no. 1, p.p. 100109 (2016) penetration, porosity, etc.) due to sufficient heat . typical microstructural features of fsw such as the sz, tmaz and haz) have the parent alloys and haz have similar microstructure. the tmaz region undergoes both heating as well as plastic g fsw because they are characterized by a structure which is deformed and is induced by the tool mechanical stirring . the sz is made by two regions composed of recrystallized very small grains made of both 2024 and 7075 al alloys ,which were composed of fine grains and equiaxed. the higher temperatures and severe plastic deformations result in remarkable smaller grains than that the parent metal, these results are in agreement with those of researcher [16], in terms of all the fsw literature data for uminum alloys; the initial elongated grains of the original materials are mechanically changed to a new fine grain structure and equiaxed these results are in agreement with those of researcher t3 and aa7075-t73). the contribution percentage of fsw process was evaluated, it was found that the speed of welding, speed of rotation and geometry of pin have 66.05%, 5.21% 15.68% contribution respectively obtained from welded joints. tensile strength of welded joints increases as the welding speed increases. muna k. abbass al-khwarizmi engineering journal, vol. 12, no. 1, p.p. 100109 (2016) 108 4it was found that the microhardness in sz is higher than tmaz and haz due to grain refinement and presence of precipitates. 5. references [1] w.m. thomas, e.d. nicholas, j.c. needham, m.g. murch, s.p. temple, and c.j. dawes, “friction stir butt welding”, international patent application no. pct/gb92/ 02203, 1991. [2] ákos meilinger and imre török,"the importance of friction stir welding tool", production processes and systems .vol. 6, 2013, pp. 25-34. [3] g.c.jadhav, and r.s.dalu ," friction stir welding – process parameters and its variables: a review", international journal of engineering and computer science , vol. 3, 2014 , pp. 6325-6328. [4] n. t. kumbhar and k. bhanumurthy," friction stir welding of al 6061 alloy", asian j. exp. sci., vol. 22, no. 2, 2008, pp. 63-74. [5] shyam kumar karna , dr. ran vijay singh , and dr. rajeshwar sahai " application of taguchi method in indian industry", international journal of emerging technology and advanced engineering. vol. 2, 2012, pp. 387-391. [6] r. palanivel and p . koshy mathews ," the tensile behavior of friction-stir welded dissimilar aluminum alloys", materials and technology, vol. 45, 2011, pp. 623–626. [7] n. t. kumbhar and k. bhanumurthy ,"friction stir welding of al 5052 with al 6061 alloys ", hindawi publishing corporation, journal of metallurgy,2012, pp. 1-7. [8] s.ravikumar, v. seshagiri rao and r.v. pranesh, "effect of process parameters on mechanical properties of friction stir welded dissimilar materials between aa6061-t651 and aa7075-t651 alloys", international journal of advanced mechanical engineering, vol. 4, 2014, pp. 101-114. [9] j.f. guo , h.c. chen, c.n. sun, g. bi, z. sun, and j. wei ," friction stir welding of dissimilar materials between aa6061 and aa7075 al alloys effects of process parameters", singapore institute of manufacturing technology (sim tech), vol. 56, 2014, pp. 185-192. [10] n rajamanickam and v balusamy, " effects of process parameters on mechanical properties of friction stir welds using design of experiments", indian journal of engineering & materials sciences, vol. 15, 2008 , pp. 293-299. [11] suresha, c. n; rajaprakash, b. m. and sarala upadhya, " optimization of process parameters for conical and cylindrical tools with grooves in friction stir welding process", advances in production engineering and management ,vol. 7, 2012, pp. 195-205 . [12] p. murali krishnaa , n. ramanaiahb and k. prasada raoc ," optimization of process parameters for friction stir welding of dissimilar aluminum alloys (aa2024 -t6 and aa6351-t6) by using taguchi method ", international journal of industrial engineering computations, vol. 4, 2013, pp. 71-80. [13] " standard test methods for tension testing of metallic materials". american association state. 2010. [14] asm handbook, “metallography and microstructures”, american society for metals, vol. 9, 2004. [15] s.ravikumar, v. seshagiri rao and r.v. pranesh," effect of process parameters on mechanical properties of friction stir welded dissimilar materials between aa6061-t651and aa7075-t651 alloys", international journal of advanced mechanical engineering. vol. 4, 2014, pp. 101-114. [16] r.madhusudhan, m.m.m.sarcar, n.ramanaiah, k.prasadarao, "an experimental study on the effect of weld parameters on mechanical and micro structural properties of dissimilar aluminium alloy fs welds", international journal of modern engineering research (ijmer) , vol. 2,2012,pp. 1459-1463. [17] ahmed a. zainulabdeen , muna k. abbass, ali h. ataiwi , sanjeev k. khanna , bharat jashti and christian widener, “ investigation of fatigue behavior and fractography of dissimilar friction stir welded joints of aluminum alloys 7075-t6 and 5052-h34 “ , international journal of materials science and engineering ,vol. 2, no. 2 , 2014 ,pp. 115-121. ��� ���س ��� �� 1، ا���د�12ا������� ا������� ا���ارز�� ،2016( 100109( 109 ا&�����م $�� ا��#"�!��#'��(� أ�-��� ��ا�, ����� ا����م !����+ ا&*#'�( ) aa2024-t3و aa7075-t73( !�4#��ام ط��0 �12(�/ ��� ���س�� * ***ر��9 ��� ا�'�ظ7 ** ��6ر ���� را5 ����/ ��� ھ���� ا����ج وا� �دن ***،**،*����ا���� � ا�� mukeab2014@yahoo.com :ا����!و�# ا�"! �* drmnthr_mm@yahoo.com : ا����!و�# ا�"! � ** rukaia1990@yahoo.com#و�!��: ا�"! � ا�� *** ا��: � $� %&' (��+�ر(� () '� �"�� ,� !-. (� &�� ا�&�7م �5�4&3 ا��2��(# و� !�1 أ(/! '� � %&/ �و�� ا�+� ;�ف ا�"97 ا��7�# ا�% �78 � ا� �ا�) ا� �;5�+� �م >�! ا��� ��ت ��"���# ا=��7& ط! $� �ef cل أ�!اء '�د ��7د �c ا����رب �4���5ام) aa7075-t73 وaa2024-t3 (و(�aءة ا� �ش#)�8 . �� .'&% ا����k ا� �aa7075 !fl'&% ا����k ا� �$�م � �ة ا�&�7م و aa2024وj i ا��"� �a&�4� د��$� و-eث �!ع ��7م ��a&�4| دورة 1710) و 1200 , 898(و�8 أ�!اء ' &�� ا�&�7م �5�4&3 ا��2��(# '��ه -eث �!ع دوران � �a&�4�pداة �-eد��$� و���5 �ل| �&� 69)و 45 , (20 ����q8) #ا��r4!وط،ا���ا�# ���c وrا� ( (���8 ا'� �د ط! $� �8(�ش# . ◦2و'�� زاو � c���ة � �� �1�aq��eت ا� &�� و-� -e�e%-اا����دا l9'&% ا���fر � � c��) �أ'�اد � � (�� �ت �c ا� ��t!ات ���� u�"r8 �8s\n ��"� أل . .ا����anova %&' vwو78&�) أل �ل '&% ����� 78&�) ��"� ألq7�و�� �8 اs\n %&/ �eت ا�� د��$� | �&� 45و�!'� ا�&�7م ، د��$� | دورة 898وا��# (��i �!'� ا��وران ، � ��د ا� ���7& �, (�aءة ا� c����ا�# rا=داة ا�� �� q878&�) ). (%76و c��$�و�� ا�+� ا�% أن �!'� ا�&�7م ھ# أ(/! '��) anovaو�� و�� %&' !-. �+�ر(� �"�� ,��eت ا=f!ى 66.05%� �c ا�. al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 6, no. 3, pp 28 35 (2010) a study of the effect of kaolin as a fuel oil additive on the corrosion inhibition of fireside superheater boiler tubes alaa' mshjel ali department of chemical engineering/ university of technology (received 2 march 2010; accepted 26 july 2010) abstract the objective of the present study is to determine the effect of kaolin as a fuel oil additive to minimize the fireside corrosion of superheater boiler tubes of astm designation (a213-t22) by increasing the melting point of the formed slag on the outside tubes surface, through the formation of new compounds with protective properties to the metal surface. the study included measuring corrosion rates at different temperatures with and without additive use with various periods of time, through crucible test method and weight loss technique. a mathematical model represents the relation between corrosion rate and the studied variables, is obtained using statistical regression analysis. using this model, the best additive to ash weight ratio was specified. then scanning electron microscopic images taken to the two treated and untreated samples with additive to study the difference in nature of slag formed on the metal surface to the two cases. keywords: kaolin effect on corrosion, corrosion in fireside boiler tubes, milting point of slag on outside tube surface. 1. introduction higher operating temperatures, the goal of every designer and user of carnot cycle limited energy systems, are not being achieved today in power plants because of serious problems with materials of construction in flue gas atmospheres. the problem in central station boilers is one of finding the least expensive superheater alloys that can tolerate continuous exposure to hot flue gas carrying fuel ash, sulfur oxides and other undesirable components. since economics limit the alloys that can be used, the problem becomes one of controlling the flue gas and the substances it carries so as to yield a reasonable life for moderately priced heat receiving surfaces. three major factors are involved in external corrosion and in the formation of deposits [1]: 1. the temperature of metal surfaces and the gas stream. 2. the composition of substances in contact with metal surfaces and the nature of those surfaces. 3. aerodynamic considerations involving gas and particle velocity and the size consist of deposited particles. metallurgical factors are important too, but only actions occurring at the outer exposed surface of metal will be considered here. several studies [2,3] , investigated the use of additives to control corrosion problems, the most effective materials for this purpose were (al2o3, sio2) [4]. a detailed work is to be conducted by this research to suggest an available and cheap inhibiting material to suit the specified characteristics based on the mentioned materials. 2. fuel contaminates it is the inorganic matter in fuels that leads to problems with corrosion and deposits. crude oil may contain (1-500 ppm) of vanadium in pyrophyren complex form, depending on the source. residual oil, a refinery concentrate, contains several times more vanadium than the crude from which it was derived. combustion of such vanadium containing fuels produces very this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ alaa' mshjel ali al-khwarizmi engineering journal, vol. 6, no. 3, pp 28-35 (2010) 29 corrosive vanadium pentoxide deposits, which can destroy superheater boiler tubes, this hot corrosion is slow at 600 oc but the rate increases rapidly with temperature rise. although vanadium removal from fuels is possible, the cost of such process cancels the economic advantage of using lower quality fuels. therefore, vanadic corrosion must be controlled with chemical additives. sulfur varies widely in crude oils, ranging from elemental sulfur to thiophene and its homologues. generally, the amount of sulfur in residual fuel is about twice that in crude oil from which it comes depending on refinery practice. its content in hydrocarbon fuels is in the (1-3%) range. sodium on the other hand causes most trouble when it is present as the chloride, sulfate and soluble organic compounds in fuel. during combustion, sodium reacts with the sulfur to form sulfate, which deposited on boiler tubes surfaces causing high temperature corrosion. 3. occurrence of corrosion corrosion is categorized as high temperature if it is found where the gas temperature is above 540 oc, as with furnace wall tubes, superheaters, reheaters. where the gas temperature is less than 540 oc as with air heaters and economizers, metal loss occurs by low temperature corrosion[5]. 4. high temperature corrosion at high temperature range (540-980 oc), sulfur in the fuel oil will convert mainly to so2. conversion of so2 to so3 takes place in the furnace depending on sulfur content, excess air and flame temperature by the reaction of so2 with atomic oxygen which formed by dissociation of molecular oxygen in the flame zone. sodium in the fuel is mainly present as nacl, readily vaporized during the combustion process, and react with h2o to produce naoh which react with so3 to give na2so4 as shown in the next equations [6]: h2o + nacl(g) naoh(g) + hcl …(1) 2naoh(g) + so3 na2so4(g) + h2 …(2) sodium sulfate formation becomes increasingly favorable thermodynamically as the temperature decreases; its presence increases the oxidation rate. when the metal is in contact with the salt, a trigger reaction occurs involving a reducing agent (r) which could be constituent of alloy [7]. na2so4 + 3r na2o + 3ro + s …(3) this step is followed by metal sulfide formation: m + s ms …(4) the second stage comprised (autocatalytic destruction) reactions: na2so4 + 3ms 4s + 3mo + na2o …(5) 4m + 4s 4ms …(6) vanadium in fuel oxidized to v2o5 during combustion which reacts with na2so4 in many reactions (as shown bellow) to form products as low as 542 oc with a eutectic of (35 mol% na2o) molten at 530 oc. the low melting compounds are the most harmful corrosives in residual fuel [8]. na2so4 + v2o5 2navo3 + so3 …(7) na2so4 + 3v2o5 na2o.3v2o5 + so3 …(8) na2so4 + 6v2o5 na2o.6v2o5+so3 …(9) 5. effects of fuel additives many additives function to control high temperature corrosion by their physical and chemical actions, and it is often not possible to separate the two actions. some mineral additives have been suggested and shown to bring positive effects to combat ashrelated operational problems (e.g. slag formation), as a result of change in ash composition in the silicate oxide systems relevant for many biomass ashes and a subsequent change in melting temperatures [8,9]. the use of clay mineral (kaolin) has shown to influence the ash chemistry by acting as a strong sorbent for sodium according to the following reactions suggested in earlier studies by tran et al [10]. al2si2o5(oh)4 al2o3.2sio2 + 2h2o …(10) al2o3.2sio2 + 2nacl + h2o 2naalsio4 + 2hcl …(11) al2o3.2sio2 + 2sio2 + 2nacl + 2h2o naalsi2o6 + 2hcl …(12) al2si2o5(oh)4 kaolinite is the dominating mineral in kaolin clay and al2o3.2sio2 (metakaolinite) is an amorphous mixture of alumina and silica when kaolinite lesser water at high temperature. naalsio4 and naalsi2o6 are high melting na-al silicate minerals formed during fuel combustion [11]. further studies [12,13], used kaolin as fuel additive during combustion of solid fuels having low melting point alkaline compositions, and this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ alaa' mshjel ali al-khwarizmi engineering journal, vol. 6, no. 3, pp 28-35 (2010) 30 found that it is particularly effective by producing high melting point alkali metal compounds during combustion. 6. experimental procedure high temperature corrosion of the superheater alloy was studied in the presence of corrosive mixture (20 wt.% sodium sulfate + 80 wt.% vanadium pentoxide) using crucible testing method [١٤]. the effect of three variables (temperature, time and kaolin/ash weight ratio) on corrosion rate was investigated and analyzed using experimental design. temperature was taken in the range (400-900 oc), while time was ranged in (2-10 hours) and additive to ash weight ratio (0-8wt.%). selected ranges divided according to box-wilson experimental design with 21 coded values for each variable as shown in the first three columns of table (2). equation (13) relates the coded and real values and then is used to calculate the second three columns of table (1) as shown. table 1, corrosion rate results according to box-willson design. x1 cod . x2 cod . x3 cod . tem . (oc) tim e (hr) add./as h (wt) c.r . gmd +1 +1 +1 794 8.3 6.3 93.24 -1 +1 +1 506 8.3 6.3 32.58 +1 -1 +1 794 3.7 6.3 77.76 -1 -1 +1 506 3.7 6.3 17.64 +1 +1 -1 794 8.3 1.7 157.5 -1 +1 -1 506 8.3 1.7 117 +1 -1 -1 794 3.7 1.7 117.9 -1 -1 -1 506 3.7 1.7 72  0 0 900 6 4 216 0  0 650 10 4 99 0 0  650 6 8 54  0 0 400 6 4 13 0  0 650 2 4 50.58 0 0  650 6 0 130.5 0 0 0 650 6 4 63 1 0 0 794 6 4 93.6 0 1 0 650 8.3 4 70.2 0 0 1 650 6 6 54 -1 0 0 506 6 4 45 0 -1 0 650 3.7 4 59.4 0 0 -1 650 6 1.7 83.7 center mincenter codedal x xx xx        . re ...(13) where: xreal is the variable real value. xcoded is the coded value according to boxwillson exp. design. xcenter is the median real value. xmin. is the minimum real value.  is the number of variables. the superheater tube alloy of astm designation (a213-t22) is used with the composition (taken from al-dora power station in baghdad) as shown in table (2): table 2, elemental ratios of boiler steel tube. element c si mn cr mo % wt. 0.1 0.5 0.40.7 2-2.5 0.91.2 the tube cut into cylindrical pieces of dimensions (5mm height, 38mm outer diameter and 25mm inside diameter). specimens were degreased, annealed and stored in desiccators, and then abraded under tap water. dimension of each specimen measured and weighed to the fourth decimal of gram. artificial ash was then prepared by mixing and grinding sodium sulfate with vanadium pentoxide at weight ratios of (80%v2o5 + 20%na2so4) using electrical mortar (type retsch-bb1a). similarly the mixture of ash with additive (kaolin) was prepared to have the proposed (additive/ash) weight ratios as shown in column 6 of table (1). the cleaned specimens were then immersed in the ash and put in a high resistance crucible and placed in the muffle furnace (type nabertherm-n20/h) under controlled temperature and time. when experimental run finished samples are taken to clean and weighed to calculate weight loss and corrosion rates as shown in column 7 of table (1). two photos of the treated and untreated slag of fractured samples were then taken using 1000x magnification scanning electron microscopy (type hitachi s3000n japan) in the university of sulaimania, kurdistan to compare the effect of additive on the structure of the formed slag. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ alaa' mshjel ali al-khwarizmi engineering journal, vol. 6, no. 3, pp 28-35 (2010) 31 1.26977ta-0.01289ta0.001822tt  222 1.847988a0.789933t0.000767t  figure (1) effect of additive ratios on corrosion rate at various temperatures additive/ash (wt%) c o rr os io n r a te ( gm d ) -20 20 60 100 140 180 220 260 -1 1 3 5 7 9 500 oc 600 o c 700 oc 800 o c 900 o c time =5hours 7. results and discussion from the practical results of corrosion rates shown in column7 table (1), a regression analysis is applied to get the polynomial of equation (2) using statistica ® kernel release 6.0. this equation represents the best form of mathematical model that relates corrosion rate (c.r.), with the three studied variables (temperature, time and additive/ash weight ratio). value of correlation coefficient was 0.9407. this model is used to plot graphical figures between corrosion rates versus each variable, and to evaluate the suitable additive/ash weight ratio. -26.51a-2.459t0.7715t-273.57c.r.  …(14) where: c.r.= corrosion rate (gmd) t=temperature (oc) t= time (hr.) a=additive to ash weight ratio (gm/100 gm ash) figure (1) shows the effect of additive/ ash weight ratio on the corrosion rate at different temperatures and at a time period of 5 hours according to equation (14). it is clearly found that increasing ratio of additive with ash mixture reduces corrosion rate and this effect appears efficiently at weight ratio (6wt %). explication of this case is due to the physical and chemical role of alumina and silica in kaolin. effect of alumina combined with silica is found to be due to the reaction with sodium sulfate and sodium chloride to produce a protective high melting point compact scale of (na2o.al2o3.2sio2)[1] and (naalsio4, naalsi2o6)[10] which prevents the transport of oxygen from the melt surface to the metal interface. silica is found to be effective due to the reaction with sodium compounds to form a series of silicates such as (na2o.sio2) which melts at (1000 oc)[1]. fig.1. effect of additive ratios on corrosion rate at various temperatures. figure (2) clarify the effect of additive on corrosion rates with time, it was found that the efficiency of additive increases with time especially after the eighth hour from the experiment beginning. that means the growth of a protective layer on the metal surface with time helps to preserve it from severe oxidation. figure (3) represents the relation between temperature and corrosion rate according to equation (14). it is clearly shown that increasing temperature range leads to higher corrosion rate, and this increase confirm the exponential relationship. efficiency of additive decreases when the temperature exceeds (600 oc) due to formation of (navo3, na2o.3v2o5, na2o.6v2o5) according to chemical reactions (4, 5, 6), these compounds catastrophically oxidize the alloy parts by acting as oxygen carriers and metal oxide distorts. figures (4) and (5) show the change in corrosion rate with time. in the two figures a similar behavior noticed with and without additive use and the difference appeared only in the range of temperature. in case of additive use a rate plot follows logarithmic equation is obtained, while without additive use an exponential equation is found; i.e. two types of scale are formed. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ alaa' mshjel ali al-khwarizmi engineering journal, vol. 6, no. 3, pp 28-35 (2010) 32 figure (3) effect of temperature on corrosion rate at different additive ratios temperature (oc) c o rr o si o n r a te ( g m d ) -20 20 60 100 140 180 220 260 350 450 550 650 750 850 950 (add./ash) wt.%=0 (add./ash) wt.%=2 (add./ash) wt.%=4 (add./ash) wt.%=6 (add./ash) wt.%=8 time =5hours figure (2) effect of additive ratios on corrosion rate at different time periods additive/ash (wt%) c o rr o si o n r a te ( g m d ) 20 40 60 80 100 120 140 160 180 200 -1 1 3 5 7 9 2 hrs. 4 hrs. 6 hrs. 8 hrs. 10 hrs. temperature =650 oc figure (4) change in corrosion rate versus time with and without additive time (hr.) c o rr o si o n r a te ( g m d ) 0 40 80 120 160 200 1 3 5 7 9 11 (add./ash) wt.%=0 (add./ash) wt.%=8 temperature= 500 oc fig.2. effect of additive ratios on corrosion rate at different time periods. fig.3. effect of temperatures on corrosion rate at different additive ratios. fig.4. change in corrosion rate versus time with and without additive. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ alaa' mshjel ali al-khwarizmi engineering journal, vol. 6, no. 3, pp 28-35 (2010) 33 figure (5) change in corrosion rate versus time with and without additive time (hr.) c or ro si on r at e (g m d) 160 180 200 220 240 260 280 300 1 3 5 7 9 11 (add./ash) %wt.=0 (add./ash) %wt.=8 temperature= 900 oc fig.5. change in corrosion rate versus time with and without additive. in case of oxidation without additive treatment a porous scale is formed; the transport occurs by an outward migration of metal by the vacancy mechanism, vacancies may collect to form cavities and pores at the metal-oxide interface and produce appreciable porosity in the oxide scale after more extended reaction, and the cavities may act as carriers to the solid state diffusion process. fig. (6) depicts a sample of slag removed from the metal surface in case without additive. fig.6. untreated slag sample. while in the case of additive treatment a compact scale is formed due to the reaction of additive materials (al2o3, sio2) with the corrosive materials to produce high melting point compounds, this scale acts as a barrier which separates metal from oxygen gas. rate of oxidation at high temperatures is limited by a solid state diffusion through the compact scale. as the diffusion distance increases by increasing oxide layer thickness, the rate of reaction decreases with time. thus compact scale offers useful protective properties from practical point of view on the important features of metals oxidation. figure (7) shows a sample of slag formed on the metal surface with additive treatment; the structure of this material is lighter, softer and is easy to crumble. structurally, the material, as seen in the highlighted area, has holes (pores) that are noticeably larger than those in figure (6). this explains why the material is much weaker and lighter than the baseline untreated material. smooth and dense areas can still be seen, but the pores are generally larger and add to the lightness and friable nature of this sample. fig.7. treated slag sample. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ alaa' mshjel ali al-khwarizmi engineering journal, vol. 6, no. 3, pp 28-35 (2010) 34 8. references [1] reid w.t., "external corrosion and deposits", americal elseveir publishing company, inc., new york, 1971. [2] krause h.h., "combustion additives for pollution control", epa, report 600/2-776089, 1977. [3] michele d.p., "influence of magnisia additives on the performance of a large power station boiler", j. inst. energy, june 1986. [4] may w.r. and zetlmeisl m.j., "inhibition of corrosion in fuels with mg/al/si combinations", u.s. patent no. (4,659,339), april 21, 1987. [5] hart a.b. and cuttler j.b., "deposition and corrosion in gas turbines", applied science publishers ltd., london, 1973. [6] johnson d.m., whittle d.p. and stringer j., "corr. sci.", 721(15), 1975. [7] ashwarth v., "corrosion, industrial problems, treatment and control techniques", pergamon press, u.k., 1988. [8] ohman m., bostrom d. and nordin a., "effect of kaolin and limestone addition on slag formation during combustion of wood fuels", energy &fuels 2004, 18:1370-1376. [9] lindstrom e., bostrom d and ohman m., "effect of kaolin and limestone addition on slag formation during combustion of woody biomass pellets", 14th european biomass conf. and exhibition, paris, france 17-21. [10] tran k.o., iisa k., steenari b.m. and lindqvist o., "a kinetic study of gaseous alkali capture by kaolin in the fixed bed reactor equipped with an alkali detector ", fuel, 2005, 84:169-175. [11] boman c., bostrom d. and ohman m., "effect of fuel additive sorbents (kaolin and calcite) on aerosol particle emission and characteristics during combustion of pelletized woody biomass", 16th european biomass conference & exhibition, 2-6 june 2008, valencia, spain. [12] zeuthen j.h., jensen p.a., jensen j.p. and livbjerg h., "aerosol formation during the combustion of straw with addition of sorbents", energy and fuels 2007; 21:699709. [13] brunner t., "aerosols and coarse fly ashes in fixed bed biomass combustion", doctoral thesis, technical university of eindhoven, eindhoved, nederlands, 2006. [14] ailor w.h., "handbook on corrosion testing and evaluation", john wiely & sons, inc., 1971. !! !! !! this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ ي جل عل الء مش د ع یة المجل وارزمي الھندس ة الخ دد ٦مجل فحة3، الع 35 -28 ، ص )٢٠١٠( 35 سة تأثیر الكاولین كمادة مضافة لزیت الوقود على منع التآكل بجانب االحتراق الخارجي درا النابیب المرجل البخاري المحمص عالء مشجل علي لوجیةوالجامعة التكن/ قسم الھندسة الكیمیائیة الخالصـة ل الھدف من ھذه الدراسة ھو تحدید تأثیر استخدام مادة الكاولین كمادة مضافة الى ب المرج زیت الوقود للتقلیل من التاكل بجانب االحتراق الخارجي النابی ات ) astm a213-t22(المحمص ذات المواصفات القیاسیة وین مركب الل تك ن خ ب م ارجي لالنابی طح الخ برفع درجة انصھار الخبث المتكون على الس دن طح المع ة لس فات واقی دة ذات مواص دالت . جدی اس مع ة قی منت الدراس ل تض ة للتآك ادة المانع تخدام الم دم اس تخدام وبع ة باس رارة مختلف درجات ح ل ب التآك .وبفترات زمنیة مختلفة من خالل طریقة قیاس البودقة وتقنیة الفقدان بالوزن ائي ل االحص تخدام التحلی ة باس رات المدروس ل . تم الحصول على مودیل ریاضي یمثل العالقة بین معدل التآكل والمتغی د افض ل لتحدی ذا المودی تخدام ھ اس ادة ال ). الرماد/المادة المضافة(نسبة وزنیة ة بالم ر المعامل ة وغی ین المعامل ي للعینت ري االلكترون ح المجھ ي بعدھا تم أخذ صور بالماس رق ف ة الف افة لدراس مض .طبیعة الخبث المتكون على سطح المعدن للحالتین this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ microsoft word corrosion of carbon steel pipeline in flow system of water al-khwarizmi engineering journal al-khwarizmi engineering journal, vol.4 , no.1 , pp 17 (2008 ) corrosion of carbon steel pipeline in flow system of water sweetening plant mohammed a. atiya biochem.eng.dept.,al-khwarizmi coll.eng baghdad university fadhil s. kadhim (m.sc.) biochem.eng.dept.,al-khwarizmi coll.eng baghdad university (received 11 february 2007; accepted 9 august 2007) abstract: the electrochemical behavior of carbon steel in water sweetening station in libya has been studied in the range of ( 293–333 oc) using weight loss technique. measurements were carried out over a range of reynolds number (5000 – 25000).an apparatus was designed for studying the corrosion process in the turbulent regime, which is of industrial significance. it was found that the corrosion rate of carbon steel in water sweetening station is under diffusion control and increases with increasing reynolds number. on the other hand the variation of corrosion rate with temperature in the range of (293–333 oc) was found to follow arrhenius equation and the activation energy approximately the same except at low reynolds number. keywords :corrosion, sweeting, carbon steel. introduction: corrosion can be defined in several ways; it is the destructive attack of metal by a chemical or electrochemical reaction with its surrounding[1] ; or it is the interaction of material with its surrounding[2] . corrosion has been a serious problem in water sweetening stations for many decades, one of very common cause of corrosion is the presence of dissolved oxygen in water and the presence of chloride ions. the corrosion rate in water sweetening stations depend on many parameters such as; chemical composition of carbon steel, temperature, velocity of flow, salt concentration , oxygen concentration, carbon dioxide , and ph index. velocity primarily affects corrosion rate through its influence o diffusion phenomena. it has little or no effect on activation controlled processes. in addition the diffusion process is affected differently by velocity when flow conditions are laminar as compared to situation where turbulence exists[3]. for most conditions, the corrosion rate can be expressed by the equation[4]: c.r.= k un ………….(1) where; k is constant, and n is a constant for a particular system. values of (n) vary from (0.2 1.0).speller and kendall[5] measured the effect of velocity of aerated water on corrosion of (1/2 in) iron pipe. the data were plotted and the constant, n, in this case turned to be 0.79.this value was similar to the results obtained by several other investigators[6]. the effects of temperature on corrosion rate may be represented by the arrhenius equation: k = a exp( -ea / rt ) …………….(2) so that ln (k) or log(k) gives a straight line when plotted vs. (1/t) with a slope of ( ea /r) or (-ea / 2.303r), r is the gas constant. many thermales processes behave in this way and an thermal arrhenius plot enables to determine the activation energy[7]. mohammed a. atiya al-khwarizmi engineering journal, vol.4 , no. 1, pp 17 (2008) 2 for no heat transfer condition across the specimen / solution interface, increasing temperature (and therefore the specimen temperature) increases the corrosion rate. the relationship is not linear, but follows the form[8]: c.r. = a exp( bt) .…..………….(3) where a and b are constants.skoulikidis and vassilio[9] studied the electrochemical behavior of mild steel in 3.5 % nacl solution at temperature between (20 to 60 oc). they found the applicability of arrhenius plot with activation energy of 6 ± 2 kcal / mole. francis and dolphin[10] studied the polarization of steel in saline solutions. they found that the c.r. increased with increasing temperature and was doubled when temperature was raised from ambient temperature to 80 oc. the relationship between the limiting current(il) and corrosion rate for concentration polarization is given by[11]: c.r = 0.0895 * il * m ………… (4) where, m, is equivalent weight. the present study is a step to understanding the corrosion of carbon steel pipe lines in flow system of water sweetening station in dranah city(libya). in different flow conditions and different temperatures by using weight loss techniques. experimental work: materials and solution: the materials used in this study is low carbon steel pipe, supplied by dinah(libya) sweetening station. cylindrical specimens having length about (10mm) and inside diameter about (30mm) were cut from carbon steel pipe. water produced from station (ph = 6.8) was used as corrosive media with the following compositions: c o m p . c l c a + + m g + + c a-h m g -h n h 4 + conc. (ppm) 2.6 1.6 0.5 4 0.5 nil specimen preparation: cylindrical specimens were cut from carbon steel pipe and they were washed and degreased with analr ethanol and acetone. they were annealed in vacuum at (600 oc) for one hours(to remove the effect of cold working[12])and then cooled under vacuum to room temperature. specimen s were abraded in sequence under running tap water by using the following emery paper grades;240,320,420,and 600,washed with tap water followed by distilled water, dried with clean tissue paper, immersed in ethanol, dried with clean tissue paper, immersed in acetone, rinsed with acetone and dried with clean tissue paper. they were then left to dry for one hour over silica gel before use. the dimensions of specimens were measured by a vernier to the 2nd decimal of millimeter and accurately weighed to fourth decimal of gram. procedure: three specimens were used in each test, they were mounted axially in teflon spacer made as part of the flow system as shown in fig.(1). the specimens were separated by teflon washers in order to prevent galvanic contact[13]. different reynolds values ( re =5000 , 10000, 15000, 20000, and 250000) , different temperatures (t = 293, 313, 333 k) were used. test duration was three days. specimens after each test were visually observed,then washed with tap water, cleaned with brush to remove the weakly adherent corrosion scale, immersed in 5% hydrochloric acid containing hexamine,washed with tap water and rinsed with distilled water,dried and then rinsed with analar ethanol,dried ,rinsed with acetone and finally mohammed a. atiya al-khwarizmi engineering journal, vol.4 , no. 1, pp 17 (2008) 3 accurately weighed to the 4th deimal of gram the average corrosion ratewas calculated from the weight losses of three specimens . results and discussions: in this technique, three specimens were used in each run. the average corrosion rate was equal to arithmetical average of the three specimens, the method of calculation of corrosion rate is as follows; c.r.=(weight loss(gm)*10-3)/(a(mm2)* time(day)*10-4) or c.r.=dw/a*t ……………………..(5) where c.r.(mdd), dw = difference weight before and after duration(gm), a(area of specimen= 3.14*dl, where ; d, is the inside diameter, l, is the length ), t is the time of duration. fig.(2) shows the variation of c.r. with flow rate at constant temperature.it is clearly influenced by the flow rate as the corrosion rate increases with increasing reynolds number at constant bulk temperature of solution. this behavior is in accordance with previous investigations [14,15,16,17].this is attributed to the increase in mass transfer coefficient which will lead to the increase of oxygen flux arriving at the metal surface and the decrease in resistance that hinders the transfer of oxygen, especially the diffusion layer thickness. fig.(3) shows that the corrosion rate with temperature for different values of reynolds number. it increases with increasing temperature. the slight influence of temperature on the c.r. in the interval of temperatures is due to the oxygen solubility decrease with the increasing temperature. the observation is in accordance with that observed by parshin et. al.[18]. but the effect is clear for higher velocity (i.e. at re greater than 25000) it is readily evident that the flow rates or reynolds no. is more significant in fluencing the c.r. than the effect of temperature. several correlations have been predicted by the number of workers are available in literature, which are satisfactorily applied to electrochemical processes under laminar and turbulent conditions. the experimental results of sherwood no. are presented in fig. (4) as a plot of sh no. versus re no. with slop less than one[19,20]. arrhenius plots log (c.r.) against(1/t) for each reynolds no. is shown in fig.(5).the figure shows that the activation energy is approximately the same except at re = 5000(i.e. at low rate of flow). conclusions: the corrosion rate of carbon steel in water sweetening station is under diffusion control and the c.r. increases with increasing reynolds number. on the other hand the variation of corrosion rate with temperature in the range of (293 – 333 k) is found to follow arrhenius equation and the activation energy approximately the same. notations: c.r. : corrosion rate. k : constant in eqn.(1). n : constant vary (0.2 1). k : reaction constant a : arrhenius constant. ea : activation energy. r : gas constant. t : temperature of electrolyte. a : constant in eqn.(3). b : constant in eqn.(3). il : limiting current density. m : molecular weight. a : surface area of specimen. d : inside diameter of specimen. l : length of specimen. re : reynolds number. sh : sherwood number. dw : difference weight before and after duration. mohammed a. atiya al-khwarizmi engineering journal, vol.4 , no. 1, pp 17 (2008) 4 teflon screw pipe flange thermocouple test section container flow meter heat exchanger valve pump drain valve fig. (1) rig system. 1 10 100 1000 1000 10000 100000 log re l o g c . r t = 333 k t = 313 k t = 293 k fig.(2) dependence of corrosion rate on the reynolds number at different temperatures. mohammed a. atiya al-khwarizmi engineering journal, vol.4 , no. 1, pp 17 (2008) 5 0 20 40 60 80 100 120 140 160 293 313 333 temperaure(k) c .r (m d d ) re =5000 re = 10000 re = 15000 re = 20000 re = 25000 fig.(3) dependence of corrosion rate on the temperature at different reynolds numbers. 10 100 1000 1000 10000 100000 log (re) l o g ( s h ) t = 293 k t= 313 k t = 333 k fig.(4) variation of sherwood no. with reynolds no. under different temperatures. 1 10 100 1000 0.0028 0.0032 0.0036 1 / t (k) l o g ( c .r .) re = 5000 re = 10000 re = 15000 re =20000 re = 25000 fig.(5) arrhenius plots of the of corrosion rate under different values of reynolds numbers. mohammed a. atiya al-khwarizmi engineering journal, vol.4 , no. 1, pp 17 (2008) 6 refrences (1) uhlig, h.h ”corrosion and corrosion control” jhon wiliey and sons inc., 2ndedition, 1977. (2) steiger wald, r,f, corrosion j., 24, jan., 1, 1968. (3) eckert, e.r, introduction to the transfer of heat and mass, mcgraw hill, new york, 1950. (4) wormwell, f., j. iron steel ins., vol.154, p.219, 1946. (5) speller, f.n. and kendall, v.v., ind. eng. chem. j., vol.15, p.134, 1956. (6) cox, g.l.and roetheli, b.e., ind. eng. chem., vol. 23, p.1012, 1931. (7) west, j.m., basic corrosion and oxidation, eliss horwood ltd., west sussex, p.40, 1980. (8) proter, d.t., donnimirska, m. and wall, r., corrosion sci, vol.8, p.833, 1968. (9) shoulikidis, n., vassiliou, p.g., corrosion j., vol.17, no.3, p.142, 1982. (10) francis, p.e., and dolphin, a.s., br. corrosion j., vol.19, no.4, p.181, 1984. (11) barnarts, s, electrochemical techniques for corrosion, 2nd, printing, naca, 1978. (12) champion, f.a., corrosion testing procedure, 2nd edition, london, champion and hill, 1964. (13) fadhil,s,kadihim,m.sc.,thesis”investi gation of carbon steel corrosion under two phase and multiphase flow in horizontal pipes”, petroleum eng. dept.,college of engineering, university of baghdad, 1996. (14) postlethwaite, j. and hurp, d.r., corrosion sci, vol. 7, p.435, 1976. (15) postlethwaite , j. and hurp, d.r., corrosion sci, vol. 7, p435, 1967. (16) chin, r.g. , and nobe, k., corrosion j. vol. 23 , p. 364 , 1977. (17) chin r.j., and nobe, k, n.m. and hakerman, n., j.electrochem. soc., vol. 102, p. 333, 1955. (18) parshin, a.g., pakhmov, v.s., and kolotyrkin, ya.m. corrosion sci., vol. 22, no.9, p. 845,1982. (19) atiya, m.a., ph.d. thesis, dept. of chem. eng., university of baghdad, baghdad, 1996. (20) ross, t.k.and hitchen, b.p., corrosion sci., 1, 65, 1961. mohammed a. atiya al-khwarizmi engineering journal, vol.4 , no. 1, pp 17 (2008) 7 تأكل أنابيب الصلب الكربوني في منظومة الجريان لمحطة تحليه المياه السيد فاضل سرحان كاظم محمد عبد عطية السراج امعة بغدادج–كلية هندسة الخوارزمي امعة بغداد ج-كلية الهندسة الخالصة: تم دراسة السلوك الكهروكيمياوي لمعدن الكرب:ون س:تيل ف:ي المحل:ول الم:ائي ف:ي محط:ة التحلي:ة ف:ي درن:ة / ليبي:ا، حي:ث ت:م ) ، ٢٥٠٠٠ – ٥٠٠٠ري::ان) م::ن () درج::ة كلف::ن ، وم::ديات رق::م رينول::دز (الج ٣٣٣ – ٢٩٣ى (دراس::ة ت::أثير درج::ة الح::رارة وللم::د لظ:رف باستخدام تقنية الفقدان بالوزن. ولغرض انجاز هذه الدرسة تم تص:ميم منظوم:ة تعم:ل تح:ت ظ:روف الجري:ان المض:طرب وه:و ا العملي في محطة التحلية. ر فأن معدل ، هذا من جانب ومن جانب آخ diffusion controlمن خالل الدراسة تبين إن عملية التآكل تحت سيطرة عملية االنتشار عملي:ة لى الق:يم العالتآكل يزداد بزيادة كل من درجة الحرارة والجريان(رقم رينولدز)،باإلضافة إلى ذلك لوحظ انطباق معادلة ارهينوس م رينولدز المنخفضة.وبتغير طفيف بأرقا (microsoft word 4755 \343\315\343\317 \310\345\314\312 \346\307\355\307\317) al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 16, no. 2, june, (2020) p. p. 4755 permeable reactive barrier of coated sand by iron oxide for treatment of groundwater contaminated with cadmium and copper ions mohammed b. abdul-kareem* ayad a.h. faisal** *,**department of environmental engineering / university of baghdad *email:mohammed.bahjet73@gmail.com **email:ayadabedalhamzafaisal@yahoo.com (received 12 january 2020; accepted 5 may 2020) https://doi.org/10.22153/kej.2020.05.002 abstract in this research, coated sand iron-oxide (csio) has been used as a permeable reactive barrier (prb) for removal of cadmium and copper ions from the contaminated groundwater. the prepared material has been manufactured by precipitation of nano-particles based this oxide type on the sand surfaces by impregnation process. therefore, this technique can be considered the main objective of the present study. the description of sorption data for sorbate-sorbent under consideration by the langmuir isotherm model was more valuable than the freundlich model. the maximum adsorption capacity of csio reaches 1.9181 and 7.6425 mg/g for cadmium and copper respectively. comsol multiphysics version release 3.5 has a good ability in the simulation and prediction of the cadmium and copper transport through one-dimensional csio-prb. the outcome of this investigation prove that the manufactured csio has significant capability in the delay of contaminants the migration through barrier packed with this material. the root means squared errors between predicted and measured data were not exceeded the 0.121; so, this means that there a good agreement between these data. keywords: barrier technology, heavy metals, isotherm, comsol, contamination. 1. introduction groundand surfacewater contamination by hazardous compounds considers an urgent issue because it has negative impacts on public health and environment. heavy metals are classified as one of hazardous compounds because they are non-biodegradable and tend to accumulate in living organisms, causing various biological disorders. both cadmium and copper ions are presented in the effluents of several industries. cadmium is one of the dangerous pollutants, originating from metal plating, metallurgical alloying, mining, ceramics, and other industrial operations [5,11]. copper mining and smelting, brass manufacture, use of cu-based agri-chemicals and electroplating industries are the major sources for pollution with this element [6,19]. the reclamation of the contaminated groundwater quality for standards specified by usepa and who within acceptable time framework can be considered a big task because it is difficult and more expensive. a pump-and-treat method is a historical technique that utilized for remediating the groundwater contaminated with different types of elements and compounds by extraction the polluted water to the ground surface and, then, treated it by conventional methods like adsorption, flotation, precipitation, and others. the resulted water from the treatment process can be disposed to water bodies, sewer system or reinjected to the aquifer. unfortunately, the collected data related to this technique certified that this system is not mohammed b. abdul-kareem al-khwarizmi engineering journal, vol. 16, no. 2, p.p. 4755 (2020) 48 effective, costly and not able to reclamation the contaminated water with acceptable periods of time. so, the permeable reactive barrier (prb) technique is introduced as an alternative method for in-situ treatment of the contaminated groundwater. this technique has many advantages;1) passive (not need any exterior source of energy), 2) underground (not effect on the activities on the ground surface), safe (no contact between workers and contaminants) and others. the prb is based on the idea of constructing a trench filled with the reactive material perpendicular on the direction of the flow where water will pass the barrier and contaminants can be entrapped within the barrier by physicochemical and biological forces [5,19]. there are a significant number of studies that directed towards the use of different sorbents in the treatment of aqueous solutions polluted with heavy metals such as activated carbon, zeolite, waste foundry sand, sewage sludge, cement kiln dust, and others [9,17]. precipitates of iron oxides have been used as promising sorbents for organic compounds metal elements [4,13]. the particles of iron oxide are fine powders and their separation from aqueous solution can be represented as a serious obstacle in the usage of this material for the treatment process. several previous studies are suggested to achieve plantation for the iron oxide on the immobilized solid supporting bed like sand, silica, cement, granular activated carbon, biomass and others [3,14]. accordingly, the importance of this work is manufacturing of iron-oxide nanoparticles-immobilized sand and use it as prbs for capturing the elements of cadmium and copper from contaminated water based on the set of the experiments and theoretical simulations. 2. experimental work 2.1 materials quartz sand with initial porosity of 36% was brought from a local market and washed carefully with distilled water before the use. the cd(no4)2.4h2o and cu(no4)2.3h2o (manufactured by himedia, india) were dissolved in distilled water to prepare the aqueous solutions contaminated with 1000 mg/l of cadmium and copper ions respectively. this solution was used to prepare the required concentration of used metals; however, the ph of the solution was changed by the addition of 0.1 m of hydrochloric acid or sodium hydroxide. the heavy metals concentrations were measured using atomic absorption spectrophotometer (aas, aa7000 shimadzu, japan). 2.2 preparation of coated sand and equilibrium experiments to prepare the sand coated with nano-particles of iron oxide (csio), the method of modified precipitation was applied [15]. the amount of 1 g sand was added to 50 ml of a solution containing 2 g fe(no3)2. to ensure the occurrence of precipitation, the naoh was added to raise the ph of the mixture. this mixture must be agitated for the duration of three hours; then, it is dried for four hours at 105◦c and thereafter the unattached iron oxide can be removed by successive washing until the ph of the wash water stabilized within the range of (7–8). the coated solids must put in the oven for drying for twenty-four hours at 105◦c and stored until usage in the sorption tests. the coating process was assessed under the effects of solution ph and sand/ferric nitrate ratios based on the achieved maximum removal efficiency of cadmium ions. the required concentration of the solutions contaminated with metal ions was obtained by dilution of stock solution. the removal efficiency was calculated by applying the initial (co) and final (ce) concentration before and after the sorption process respectively as follows [7,10]: r = ������� �� × 100 …(1) the isotherm data were obtained by taking 50 ml with different concentrations (5-100) mg/l of cd(ii) and cu(ii) solutions and distributed into different conical flasks at ph =5. the 1 g of coated sand by iron oxide (csio) must distribute on the conical flasks which agitated by the shaker for three hours at room temperature to enhance the transport of metal ions from the liquid phase to solid phase until the reaching of equilibrium status. these sorption measurements are fitted with the langmuir and freundlich isotherm models that represented by eqs. 2 and 3 respectively [1,7,8, 16,18]: � = ��c� � �� …(2) � = ������� ����� …(3) where � was the amount of metal ions adsorbed at equilibrium (mg/g). the constants �� and 1/� are freundlich constants which reflect the adsorption capacity and intensity respectively. also, the b and ��� are affinity constant (l/mg) and maximum adsorption capacity (mg/g) for langmuir isotherm respectively. mohammed b. abdul-kareem al-khwarizmi engineering journal, vol. 16, no. 2, p.p. 4755 (2020) 49 2.3 continuous study the diagram for column setup utilized for representation the contaminant transport is illustrated in figure 1. this setup consists of three perspex columns and each column has dimensions of height = 50 cm and diameter = 2.5 cm. each column was supplied with ports p1, p2 and p3 at distances of 10, 20, and 30 cm as clear in this figure. the ports were assembled with stainless steel fittings and viton stoppers can be for blockage them. by using the syringes, the water samples have been taken periodically from the column center. each column was packed with 30 cm of csio and this bed must saturate with distilled water by feeding it from the bed bottom in the upward direction. using a constant head tank with a flow-meter and four valves, the contaminated solution was introduced into the beds for the column-1, -2 and -3. the flow rates of (5, 10, and 15 ml/min) with an initial concentration of (10, 20, and 30 mg/l) are tested in the present experimental program. the concentrations of cd(ii) and cu(ii) at locations are identical in ports p1, p2 and p3 and measured by aas for a period not exceeded 13 days. the measurements are also included the monitoring of the accumulative aqueous solution volume with time and results proved that the flow rate values remained constant through each experiment. fig. 1. laboratory-scale column setup. 3. results and discussion 3.1 preparation of csio the ph effect of aqueous solution associated with fe(no3)2 concentration and also the mass of sand on the removal efficiency for cd(ii) ions were evaluated as showen in figure 2. this figure proved that the increase of fe(no3)2 solution ph from 5 to 12 can cause a significant increase in the removal efficiency by csio. the precipitation of ferric hydroxide on the solid particles surfaces was achieved by changing the ph to became > 3 (11). in addition, the removal efficiency be csio was approximately stabilized the ph 11; so, this value can be chosen for the coating of sand by iron oxide. then, the mass of sand used in the coating process was changed within the range from 0.5 to 10 g added to 50 ml of solution contained on 2 g of fe(no3)2. the removal efficiency of cd(ii) ions was increased with an increase in the sand dosage from 0.5 to 5 g (0.25 to 2.5 sand dosage /ferric nitrate). the washing after ending the process of preparation can be applied to remove the uncoated iron oxide. therefore, the sand dosage of 5 g (2.5 sand dosage /ferric nitrate) was proposed for the achieving of the coating process. fig. 2. effect of a) ph and b) sand mass on the cd(ii) removal efficiency onto csio. mohammed b. abdul-kareem al-khwarizmi engineering journal, vol. 16, no. 2, p.p. 4755 (2020) 50 3.2 sorption isotherms langmuir and freundlich's models are fitted with sorption data for the interaction of cadmium and copper ions with csio for qe (mg/g) with ce (mg/l) as shown in figure 3. the fitted constants with statistical measures have been calculated from nonlinear regression microsoft excel (2016) [1,7,8, 16,18] as listed in table 1. this figure in conjugation with a determination coefficient (r2) and the sum of squared errors (sse) elucidated that the model of langmuir is more representative of sorption data. table 1, values of parameters for models of langmuir and freundlich for removal of cadmium and copper onto csio. fig. 3. isotherms models for cadmium and copper ions sorption onto csio. 3.3 breakthrough curves the breakthrough curves for the propagation of cadmium and copper fronts measured at certain locations along the csio packed columns are plotted in figures 4 to 6 under the different values of initial concentration and flow rate. a significant decrease in the concentrations of contaminants can be recognized due to the change of depth from 10 to 30 cm for all magnitudes of initial concentration and flow rate. remaining of the polluted water for the long duration within the bed may be the cause for this result; however, this was improved the sorption process. with time, the barrier functionality decreases significantly because of the decrease of retardation factor due to saturate of the bed with sorbed metals. for initial concentration at a certain location, plotted results signified that the migration of the metal front relates directly with the flow velocity; so, the higher flow rate means faster transport for contaminant and this accompanies with decreasing of time required for achieving the state of equilibrium. also, the increase of initial metal concentration will enhance the saturation of the bed with this contaminant more quickly due to the increase of the mass transfer driving force. the shapes of breakthrough curves are to be sharper due to the increase of metal concentration [12]. to represent the experimental measurements mathematically, the advection dispersion equation (eq.4) can be solved numerically by the finite element method through the application of comsol multiphysics 3.5a (2008). this equation plots the contaminant transport in the column packed with csio porous medium and it can be written as follows: d" # $� #"$ % v" #�#" = r #� #' …(4) where c is the contaminant concentration, dz is the dispersion coefficient, vz is the flow velocity. because the sorption of solute onto csio is more represented by the langmuir model, the retardation factor (r) is expressed as follows: r = 1 ( )* + , �..�/�∗1.232. ���1.232.��$4 cadmium …(5) r = 1 ( )* + , 5.3678∗1.188. ���1.188.��$4 copper …(6) where n is the porosity and ρb is the bulk density. to complete the modeling process, the dispersivity must be calculated for the medium under consideration. experimental measurements for the coefficient of longitudinal dispersion (dl) versus velocity (v) through csio can be described by the following linear relationship [9]: d9 = 6.49 v ( 0.5325 r2=0.996 … (7) by similarity of this equation with the following formula, dispersivity (α) can be evaluated: d9 = α v ( d∗ …(8) where d* is the coefficient of effective molecular diffusion. the outputs of solution for physical problem are illustrated in figure 1 by applying comsol on the eq.4 and are plotted together with the experimental measurements as shown in figures 4 to 6. all magnitudes of csio with initial and boundary conditions for the present problem are model parameter value cd(ii) cu(ii) langmuir qmax (mg/g) 1.9181 7.6425 b (l/mg) 0.3639 0.0559 r 2 0.9928 0.9804 sse 0.0178 0.5496 freundlich kf 0.5450 0.8536 1/n 0.3170 0.4634 r 2 0.9657 0.9278 sse 0.0740 2.0936 mohammed b. abdul-kareem al-khwarizmi engineering journal, vol. 16, no. 2, p.p. 4755 (2020) 51 listed in table 2. the predicted concentrations of cadmium and copper ions by the numerical solution for different flow rates, initial concentrations and bed depth showed that the contaminant plume is hindered by csio and the contaminant concentration levels reaching the outlet of the column may be low in the initial times and then increased with the time. satisfactory matching between the predicted values and experimental results for cadmium and copper concentrations was observed with root mean squared errors [2] that did not exceed 0.121. fig. 4. comparison between model predictions and experimental measurements for the normalized concentration of cadmium under the effects of initial concentration and bed depth. fig. 5. comparison between model predictions and experimental measurements for normalized concentration of copper under the effects of initial concentration and bed depth. mohammed b. abdul-kareem al-khwarizmi engineering journal, vol. 16, no. 2, p.p. 4755 (2020) 52 fig. 6. comparison between model predictions and experimental measurements for the normalized concentration of cadmium and copper under the effects of flow rate and bed depth. table 2, the information utilized in the simulation of contaminant transport in a column packed with csio. item parameter value csio depth (cm) 30 porosity (n) 0.45 αl * (cm) 6.49 ρb (g/cm 3 ) 1.363 initial condition co ** (mg/l) zero boundary conditions conc. @ z=0 (mg/l) 10, 20, 30 advective flux @ z=30 cm zero *longitudinal dispersivity, ** initial concentration 4. conclusions coated sand by iron oxide (csio) that prepared by plantation of nano-sized-iron oxide onto immobilized-sand through simple impregnation process proved its ability in the remediation of contaminated water. mainly, csio was applied in the permeable reactive barrier for removal of cadmium and copper ions from aqueous solutions in the batch and continuous tests. the sorption data were described in better form by the langmuir isotherm model in comparison with the freundlich model where the coefficient of determination (r 2 ) was more than 0.98. the maximum adsorption capacities for cadmium and copper onto ciso reached to mohammed b. abdul-kareem al-khwarizmi engineering journal, vol. 16, no. 2, p.p. 4755 (2020) 53 1.9181 and 7.6425 mg/g respectively. the results of comsol multiphysics 3.5a certified that the barrier is efficient in the delay of contaminant migration due to a decrease of both flow rate and inlet concentration as well as the increase of bed depth. however, a good agreement between the predicted and experimental results was observed with root mean squared errors not exceeded 0.121. 5. references [1] abd ali, z.t., naji, l.a., almuktar, s.a.a.a.n., faisal, a.a.h., abed, s.n., scholz, m., naushad, m., ahamad, t., 2020. predominant mechanisms for the removal of nickel metal ion from aqueous solution using cement kiln dust. j. water process eng. 33, 101033. https://doi.org/10.1016/j.jwpe.2019.101033 [2] bair, e.s., 2016. applied groundwater modeling-simulation of flow and advective transport. groundwater 54, 756–757. https://doi.org/10.1111/gwat.12464 [3] benjamin, m.m., sletten, r.s., bailey, r.p., bennett, t., 1996. sorption and filtration of 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modification of langmuir model for simulating initial ph and temperature effects on sorption process. sep. sci. technol. 1–8. https://doi.org/10.1080/01496395.2019.1655 055 [17] phuengprasop, t., sittiwong, j., unob, f., 2011. removal of heavy metal ions by iron oxide coated sewage sludge. j. hazard. mater. 186, 502–7. mohammed b. abdul-kareem al-khwarizmi engineering journal, vol. 16, no. 2, p.p. 4755 (2020) 54 https://doi.org/10.1016/j.jhazmat.2010.11.06 5. [18] saad, n., abd ali, z.t., naji, l.a., aah faisal, a., 2019. development of bilangmuir model for description initial ph and temperature effects on the sorption of cadmium onto waste foundry sand. environ. eng. res. https://doi.org/10.4491/eer.2019.277 [19] yu, b., zhang, y., shukla, a., shukla, s.s., dorris, k.l., 2000. the removal of heavy metal from aqueous solutions by sawdust adsorption removal of copper. j. hazard. mater. https://doi.org/10.1016/s03043894(00)00278-8 � ا����� �� )2020( 4755، ��� 2ا���د، �16��� ا���ارز�� ا� ����� ا����� ���� � 55 ا�����0 ا���/�� ا���#ه ���#��� ا����� �-و+*�� �(��� ر�#ل �' ا����ن ا���#ذ ا�$�# �� ا��#"! وا���#س ا��#د���م �-��2#ت ���� �� � � **/�67 ا���!ة � ا�#د * ا����� 78,اد 2345%/ 01/ ا(.-,+% ا()&'&% *،** mohammed.bahjet73@gmail.com*ا()=a, ا@(?<=و;:: ayadabedalhamzafaisal@yahoo.com**ا()=a, ا@(?<=و;:: ا��8 � ا(-\4ذ ا(<\hx4: ا(r54l ]: وا+<z,ا4.3 ا(=43ل +tiح whx ا@وu)v) ,&0j ا(-at;4% ا(ars'4ت no p&+=eل m3 ا(k8 ,a,lوhi3 ,&0j&% ر43ل c&-de ان ا(4cدة c3 ا(4cزة ا(4cدة s&>; ix4\e% ا@r>3از 8&4;4ت e g&hte/. ا(h) %&)4l,را+% ا(=f&0: ا(.,ف ا(dthc% ا(ts]&% ا(c&4ه m3 وا(-4lس ا(?4دt&3م اta;4ت _زا(% ا(hic&% ا(=43ل z>+48,ام ا@r>3از (h84q&% 1&/ اwhx ان وq) ,5,. ]=ا;,(tc; pذج m3 أ]4j inن وا(vي @;?tc; =&cذج noل i?k8 ,&5 m3 ا(,را+% 1&, ا(r>ccة ,&0jوk8 ,a,l)ا rhhو w)7/ ٧.٦٤٢٥و 1.9181 اh3//x i?) m3 مt&34س ا(?4دl-)وا whx :)اt>)ا .r(dا y34;=8 comsol multiphysics 3.5a ze1,ر whx 4ةj4l3 {(->)4ل واq>;48 مt&34س ا(?4دl-)وا m3 لno r54ح :hx4\e اح, ا()2, ذو ;\4ذt)ن اt?c)وا m3 ر43ل %&hi3 ,&0jوk8 ,a,l)ا .r>(dأ yf4>-)4دة ان اc)ا %2-dc)3% ا,z>0c)ا mcا ضvھ r54l)رة (.4 ا,q)ا whx =&oke 4لq>;4ت اdthc)ح�. اt) ر انv5 ع 23,لtcs3 4ءioا� m&8 yf4>-)21% اt>c)4+% اqc)4وز @ واs>a .ا()&4;4ت te ,&5 m&8 uheا]� وt5د 2a-: وھvا 0.121 66 al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 4, no. 3, pp 66-73 (2008) mass-transfer characteristics of airsuction type fermentors alaa k. m. genetic engineering and biotechnology institute for postgraduate studies/ university of baghdad iraqbaghdad (received 17 february 2008; accepted 17 june 2008) abstract liquid-side mass-transfer coefficients (kla) were measured in air-suction type fermentors using physical absorption of oxygen. a fermentor of 0. 5 m i.d. was used with a working capacity of 60 liters of liquid. tap water was used as the liquid phase, and air was used as the gas phase. the bioreactor mixing system consists of shrouded-disk/curved-blade turbine with six evacuated bending blades. the effect of liquid submergence (s) was investigated. further, the effects of the ratio of the impeller diameter (d) to the tank diameter (t), and the clearance of the impeller from the tank bottom(c) were also studied. the agitation speed (n) was varied in the range of 50-800 rpm. it was found that the value of kla increased as the impeller diameter increased, while it was decreased continuously with increasing the clearance. the effect of impeller submergence on the value of mass transfer coefficient (kla) is not much pronounced. suitable correlation was developed for estimating mass transfer coefficient (kla) in this type of bioreactors. 0.0120.230.360.73l ) d s () d c (frre5.3x10 n ak  keywords: fermentors, air–suction impeller, mass transfer coefficient. 1. introduction the important functions of aeration in fermentors include oxygen transfer, liquid phase mixing to ensure oxygen availability in all parts of the contactor, and suspension of microorganisms. in addition to these applications, there are many reactions, such as hydrogenation, alkylation, oxidation, etc. during the past 30 years, substantial work has been reported on aerators in efforts to: (1) estimate the critical conditions for the onset of aeration, and (2) elucidate the effects of various parameters on the mass transfer rates (fuchs, et al.,1971), ( takase, et al., 1984). there are two distinct regimes in the aeration process. at lower impeller speeds, the liquid surface is visually distinct, or bubbles are not present in the liquid. under these conditions, mass transfer across the interface occurs by the mechanism of surface renewal by turbulent eddies in the liquid. at higher impeller speeds, larger eddies are formed near the interface, and these eddies can entrap bubbles by overcoming the resistance of surface tension (patil, et al., 1999). the gas-liquid interface (a) available for mass transfer increases many fold as a result of turbulence aeration (ognean, t. 1997). the intensity and frequency of the eddies depend on the tank geometry, the impeller geometry, the ratio of the impeller diameter to the tank diameter, the position of the impeller in the tank, the impeller speed, and the properties of the liquid such as its surface tension and viscosity (matsumura, et al., 1982). in the published literature, mass-transfer characteristics are reported for reactors with four-bladed rushton turbine (zlokarnik, 1979), van-disk turbine (backharst et al.,1998 ), radial impeller closed from bottom (ognean,1993). the effect of clearance and submergence on mass transfer coefficient was studied in surface aerator impeller (patil, s. s. and joshi, j. b., 2004). effect of clearance between two impellers in a dual agitator was also investigated (shukla,v.b et. al.2001). in multiple system the effect agitation speed on mass alaa k. m. al-khwarizmi engineering journal, vol. 4, no. 3, pp 66-73 (2008) 67 transfer coefficient was investigated (patil, s. s. and joshi, j. b., 2003). the aim of the present work is to study the effect of the impeller design parameter such as diameter, clearance, submergence, agitation speed on the mass transfer coefficient (kla). 2. materials and methods investigation was carried out in 0.5 m i.d. gasinducing type of mechanically agitated reactor of 60 liter liquid capacity. the schematic diagrams of the bioreactor and the experimental setup are shown in figure 1. the design details of vessel are given in table 1. the prime mover was a dc motor, driven by a thyristor-controlled power source. the speed of rotation of the shaft was controlled by regulating the voltage applied to the armature of the motor by a ten-turn potentiometer. fixed pulleys and twin c section were used to connect the agitator shaft to the motor. the entire device was able to control the speed. the bioreactor mixing system consists of shroudeddisk/curved-blade turbine with six evacuated bending blades as shown in figure 2. the reactor tank, the central draft tube, the aeration wheel disk and hub were made of stainless steel. the air ducts were also stainless steel tubes, which were welded to the disk. the assembly was tinned and the hub was turned to fit a vulcanite sleeve in the bottom guide bearing. the shaft was made of ¾ inch stainless steel pipe. the cap for the introduction of air was bored to a tight running fit. table (1) shows the dimensions of the agitated fermentor and the range of variables studied. table 1 design details of gas-inducing mechanically agitated contactor. diameter of vessel, t 0.5 m impeller diameter, d t/3 , t/5 (t=0.5 m) baffle width 10% of vessel diameter. number of baffles 4 construction material stainless steel. geometry cylindrical with flat bottom lower impeller clearance from bottom, c 1.5d ,2d, 2.5d, 3d (d=9cm) submergence of upper impeller from the top liquid surface, s 0.5d, 1d, 1.5d. (d=15 cm). the mass-transfer coefficient was measured by the unsteady-state oxygen absorption method. the tap water (at a temperature of 23-27°c) was deoxygenated by chemical reaction with sodium sulfite. a dissolved oxygen meter was used to measure the rate of oxygenation. the amount of dissolved sodium sulfite was too small to change mass-transfer properties of the water. the rate of oxygen transfer is given by ...(1) )ca(ck dt dc m * ml m  (patil, s. s. and joshi, j. b., 2004). where cm is the dissolved oxygen concentration in the reactor at time t and cm * is the saturation concentration of oxygen in water in the reactor. the latter concentration was measured by allowing aeration to proceed until a constant value had been attained. experiments on oxygen probes used in this work showed that the probes gave first-order responses, with time constants of around 5 seconds. the expression for this kind of probe can be written as ...(2) )c(c k td c d pmp p  where cp is the oxygen concentration measured by the probe and kp is the probe constant. the values of the latter depend on the transport characteristics of the probe membrane, the nature of the electrolyte layer, and the electrochemical reaction at the cathode surface. we now introduce the following dimensionless quantities ...(3) cc cc x po * p p * p p    (4) ... cc cc x mo * m m * m m    then, eqs 1 and 2 can be rewritten in dimensionless form as ...(5) x ak td x d ml m  ...(6) )x (x k td x d pmp p  in these expressions, cpo and cmo represent the concentrations of dissolved oxygen at time t = 0, and cp * represents the probe saturation concentration. note that cpo = cmo and cp * =cm * . simultaneous solution of eqs 5 and 6 yields ...(7) akk ekek x lp tk la atk p p pl     the value of kp , needed to solve eq. 7 for kla, can be determined from the probe response to a step input. for example, one could apply a alaa k. m. al-khwarizmi engineering journal, vol. 4, no. 3, pp 66-73 (2008) 68 negative step input by transferring the probe from a container of water saturated with dissolved oxygen (cm=cm*) to a container of oxygen-free sulfite solution (cm=0) and noting the probe reading. for this case, eqs. 5 and 6 become ...(8) )c(c k td c d p * pp p  ...(9) x k td x d pp p  eqs. 8 and 9 represent a special case of eqs 5 and 6 where xm is replaced by xp * . kp values for the probe were checked before and after each set of experiments. variations in kp values were not significant. from each aeration experiment, a set of values of xp(actual) (called xpa) was obtained as a function of time. by assuming a value of kla, the value of xp (equation) (xpe) for a given time was calculated with eq 5. then, the value of the error for a given kla and a given time was calculated according to ...(10) ) x xx (error 2 pa pepa   the value of kla for given set of experiments was calculated by minimizing the total error (iterative calculation of above procedure) using the golden section optimization algorithm. the value of kla was calculated with the assumption that the liquid phase was completely mixed. to confirm the liquid-phase mixing behavior, the oxygenation conditions (and hence kla) were measured at different points (figure 1): near the tank bottom (p-1); at the tank wall (p-2); and near the impeller (p-3); gas was always dispersed at p2 and p-3. it was observed that, the value of kla was practically the same at all three points (figure 3). fig.1. schematic diagram of the experimental diagram. fig. 2. laboratory experimental fermentor with mechanical aerator. transmission system d.c motor t h c s d p-1 p-2 p-3 flow meter air cap aeration wheel bottom bearing shaft bushing hollow shaft pulley ball bearing fermentor assembly a a section a a aeration wheel b a alaa k. m. al-khwarizmi engineering journal, vol. 4, no. 3, pp 66-73 (2008) 69 0.000 0.005 0.010 0.015 0.020 0.025 0.030 0.035 0.040 0.045 0.050 0 50 100 150 200 250 300 350 400 450 rpm m a s s t ra n s fe r c o e ff ic ie n t, k a ( 1 /s ) p-2 p-1 p-3 fig. 3. mass transfer coefficient at different prop location;p-1 at tank bottom, p-2 at tank wall in the impeller plane, p-3 neer the impeller. 3. results and discussion 3.1 effect of impeller diameter the effect of the impeller diameter d was studied with d= t/3 and d=t/5 impellers (figure 4). in the lower range of rpm (<300), the d=t/5 impeller was found to exhibit relatively high values of kla however, as the rpm increased beyond 300, the rate of increase in kla with respect to rpm was diminished as a result of poor liquid circulation. this effect could be visually observed in terms of the gas dispersion characteristics. for rpm > 300, the gas hold-up in the top portion was found to increase with rpm but the depth of gas dispersion was found to decrease and the value of kla is nearly constant. the kla values of the d=t/3 impeller were found to be higher. a similar trend was observed in the case of the surface aeration impeller(patil, s. s.; joshi, j. b. 2004) the effect of the impeller diameter was studied with t/3 and t/5 impellers in the lower range of power consumption(p/v < 100 w/m3). the t/5 impeller was found to exhibit high values of kla. however, as the power consumption increased beyond 100 w/m3, the rate of increase in kla with respect to p/v was diminished as a result of of poor liquid circulation. 0 0.01 0.02 0.03 0.04 0.05 0 100 200 300 400 500 600 rpm m a s s t ra n s fe r c o e ff ic ie n t, k a ( 1 /s ) d=t/5 d=t/3 fig. 4. effect of impeller diameter (s=just submerged, t=0.5 m, c=1.5 d). alaa k. m. al-khwarizmi engineering journal, vol. 4, no. 3, pp 66-73 (2008) 70 3.2. impeller submergence in the air-suction reactor, the stator protects the forced vortex, and irrespective of impeller submergence, the gas-liquid interface can approach very near to the impeller, especially at relatively high impeller speed at which bubble entrapment and subsequent transport become essentially independent of s. the effect of submergence was studied in the range: s= 0.5d to s=2d. from figure (5), it can be seen that the effect of impeller submergence on the value of mass transfer coefficient (kla) is not much pronounced. in the air suction impeller gas bubbles are entrapped into the surface waves and eddies formed by the impeller (wu, h. 1995). with increasing submergence, the number of eddies at gas-liquid interface are decreased while the liquid circulation velocity increases with increasing submergence. the combined effect of bubble entrapment, and liquid circulation results in a nearly constant value of kla. with respect to s. backhurst et al. (1998) made similar observations in the case of a vane-disk turbine. 0 0.01 0.02 0.03 0.04 0 0.5 1 1.5 2 2.5 impeller submergence, s/d m a s s t ra n s fe re c o e ff ic ie n t k a ( 1 /s ) rpm=100 rpm=300 rpm=400 fig. 5. effect of impeller submergence on mass transfer coefficient (t=0.5 m, d=t/5, c=1.5 d). 3.4. effect of impeller clearance the effect of impeller clearance (c) at constant impeller submergence (s) is shown in figure (6). with the d=t/5 impeller diameter, the clearance was varied in the range of (c=1.5d – c=3d). the value of kla was found to decrease continuously with increasing clearance. increasing the clearance cause the region near the fermentor bottom to become a weak agitation or a dead zone region and hence the turbulence within the fluid decrease , the point which decreases the value of kla. similar finding was observed by patil, s. s. (2003) in studying the clearance in multiple impeller system. 0 0.01 0.02 0.03 0.04 0.05 1 2 3 4 bottom clearance c/d m as s t ra n sf er c o ef fi ci en t, k a ( 1 /s ) rpm=400 rpm=200 fig. 6. effect of bottom clearance on mass transfer coefficient (t=0.5 m, d=9 cm, s=1.5d). alaa k. m. al-khwarizmi engineering journal, vol. 4, no. 3, pp 66-73 (2008) 71 3.5. mathematical correlation for establishing mathematical correlation between mass transfer coefficient (kla), and the variables studied : rotation speed (n), impeller bottom clearance (c) , impeller submergence from top liquid level (s), the experimental data for this system were analysis using the multiregression method. owing to the different variation of mass transfer coefficient (kla), the equation has been proposed is: ...(11) ) d s () d c (frre5.3x10 n ak 0.0120.230.360.73l  similar correlation was developed for estimating the mass transfer coefficient for multiple impeller system (patil, s. s.and joshi, j. b. 2003) 1.08 3 0.54 0.820.480.71 p 6l d v d h refrn7x10 n ak                the parity plot shown in figure 7. show that the correlation coefficient for above equation was found to be 0.96. 0 0.001 0.002 0.003 0.004 0.005 0.006 0 0.001 0.002 0.003 0.004 0.005 0.006 experimental kl.a / n p re d ic te d k l .a / n fig. 7. parity plot of mass-transfer correlation for air-suction impeller (eq. 11). 4. conclusions 1the effect of the impeller diameter d was studied with d= t/3 and d=t/5 impellers. the kla values of the d=t/3 impeller were found to be higher. 2the effect of submergence (s) was studied in the range :s= 0.5d to s=2d. it can be seen that the effect of impeller submergence on the value of mass transfer coefficient (kla) is not much pronounced. 3the effect of impeller clearance (c) at onstant impeller submergence (s) was studied in the range of (c=1.5d – c=3d). the value of kla was found to decrease continuously with increasing clearance. 4mathematical correlation for estimating mass transfer coefficient (kla) has been proposed: 0.0120.230.360.73l ) d s () d c (frre5.3x10 n ak  alaa k. m. al-khwarizmi engineering journal, vol. 4, no. 3, pp 66-73 (2008) 72 5. nomenclature a interfacial area per unit volume (m2/m3). c* saturated oxygen concentration, c*m c*p (g/l). cm oxygen concentration in the reactor (g/l). c*m saturated oxygen concentration in the reactor (g/l). cp oxygen concentration measured by probe (g/l). c*p saturated oxygen concentration measured by probe (g/l). c0 oxygen concentration at t = 0, cm0, cp0 (g/l). c impeller clearance from tank bottom (m). d impeller diameter (m). fr froude number, n 2 d/g. g gravitational acceleration (m/s 2 ). h liquid height (m). kla mass-transfer coefficient (s -1 ). kp probe constant (s -1 ). n impeller speed (s -1 ). np impeller power number, (p/ρ n 3 d 5 ). p power consumption (w) re reynolds number, nd 2 ρ/µ s impeller submergence (m) t tank diameter (m) t time (s) v liquid volume in the reactor (m 3 ) xm dimensionless oxygen concentration in the reactor xp dimensionless oxygen concentration measured by probe xp* dimensionless saturated oxygen concentration xpa dimensionless actual oxygen concentration measured by probe xpe dimensionless equated oxygen concentration measured by probe ρ liquid density. (kg/m3) µ liquid viscosity. (pa.s) 6. references backhurst, j. r.; harker, j. h.; kaul, s. n.(1998) the performance of pilot and fullscale vertical shaft aerators. water res., 22, 1239. fuchs, r.; ryu, d. d.; humphrey, a. e. ( 1971) effect of surface aeration on scale-up procedures for fermentation process. ind. eng. chem. process des. dev., 10, 190. matsumura, m.; sakuma, h.; yamagata, t.; kobayashi, j. (1982) performance of oxygen transfer in a new gas entraining fermentor. j. ferment. technol., 60, 551. ognean, t.(1993) dimensionless criteria for estimating oxygen transfer in aeration system. biotechnol. bioeng. , 41, 1014. ognean, t. (1997) relationship between oxygen mass transfer rate and power consumption by vertical shaft aerator. waterres, 31, 1332. patil, s. s.; joshi, j. b. (1999) stability of gas inducing type impellers. can. j. chem. eng., 55, 793. patil, s. s.; joshi, j. b. (2004) mass transfer characteristics of surface aerators impellers. ind. eng. res. 43, 2765. patil, s. s.; joshi, j. b. (2003) optimum design of multible impellers system. ind. eng. res. 42,1261. shukla, v.b.; veera, u.p.; kulkarni,p.r.; pandit, a.b.(2001) scaleup of bioreactor process in stirred tank reactor using dual impeller bioreactor. biochemical engineering journal. 8, 19. takase, h.; unno, h.; akehata, t. (1984) oxygen transfer in a surface aeration tank with square cross section. int. chem. eng., 21, 128. wu, h. (1995) an issue on applications on applications of a disk turbine for gas-liquid mass transfer. chem. eng. sci., 50, 668. zlokarnik, m. (1979) scale-up of surface aerators for wastewater treatment. adv. biochem. eng., 11, 157. alaa k. m. al-khwarizmi engineering journal, vol. 4, no. 3, pp 66-73 (2008) 73 خواص انتقال المادة في المخمراث راث الخالطاث الساحبت للهواء عالء كريم محمذ جاهعت بغذاد /هعِذ الٌِذست الْساث٘ت ّالخقاًاث االح٘ائ٘ت للذساساث العل٘ا الخالصت suction) لزّباى االّكسج٘ي فٖ ّسط سائل فٖ ًْع هي الوخوشاث راث الشٗش الساحبت للِْاء (kla) حن حساب هعاهل اًخقال الوادة air impeller) .اسخخذم هاء . سائل ( لخش60) ّسعت حجو٘ت ( م0.7)ّاسحفاع ( م0.5) اسخخذم فٖ ُزا البحث هخوش اسطْاًٖ راث قطش -shrouded)الخـالط الوسخـخذم هي ًـْع الشٗــش الوٌحـٌ٘ت الوجـْفت الساحبت للِْاء. الحٌف٘ت كطْس سائل، ّالِْاء كطْس غاص disk/curved-blade turbine with six evacuated bending blades) ، عوق الخالط عي هسخْٓ السطح (d) ، قطش الخالط الوسخخذم(n)سشعت دّساى الخالط: اسخخذهج فٖ ُزٍ الذساست الوخغ٘شاث االح٘ت حضداد باصدٗاد قطش الخالط، بٌ٘وا حقل ق٘وخَ باسخوشاس (kla )ّجذ اى ق٘وت . (c)اسحفاع الخالط عي قعش الوخوش، ّ(s)العلْٕ لْسط السائل (.kla) علٔ ق٘وت (s) عوق الخالط عي هسخْٓ السطح العلْٕ لْسط السائل كزلك ّجذ عذم حاث٘ش.(c)صٗادة اسحفاع الخالط عي قعش الوخوش (:dimensionless groups) ّفق هعادلت حجشٗب٘ت راث هجاه٘ع عذٗوت الْحذاث(kla)حن سبط ُزٍ الوخغ٘شاث هع هعاهل اًخقال الوادة 0.0120.230.360.73l ) d s () d c (frre5.3x10 n ak  study the axail dispersion model in ion exchange column al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 5, no. 4, pp 1-12 (2009) study the axail dispersion model in ion exchange column iman hahider mahdi department of chemical engineering/ collage of engineering/ alnahreen university (recived 31 january 2008; accepted 3 march 2009) abstract a mathematical model is developed which predicates the performance of cylindrical ion exchange bed involving comparing of axial dispersion model for cation exchange column with different assumption, this model permits the performance to predicate the residence time within the bed with the variance, axial dispersion and pecklet no. to indicated deviation from plug flow model. two type of systems are chosen for positive ions first with divalent ions (ca+2) to exchange with resin of na+1form used as application in water softener units and second with monovalent ions (na+1) to exchange with resin of h+1 form used as application in deionize water units with two parameters effected in the operation of the two systems different flow rate and different feed concentration by their effect on axial dispersion in each one where the system are compare from the performance which describe in term of breakthrough time other parameters (the time equivalent to usable capacity "tu" , time equivalent to equilibrium capacity "tt" and length of unused bed "hunb") are calculated in the operation condition that with axial dispersion are very important in predicated the best condition to operation the cation exchange column as a softener and deionize units. keywords: ion exchange, axil dispersion, ca+2 ion, na+1ion, pe no., breakthrough time, height of unused bed (hunb), residence time, variance 1. introduction over the past decades the ion exchange processes has found increased applications in a range of diverse fields. most of these applications use cylindrical column ion exchange beds in which the electrolyte solution to be treated is injected in one end and the effluent is collected at the other such as water softner when treated a solution of divalent ion (ca +2 ,mg +2 ) with using cation exchange column with na-form to exchange divalent , other application is the dionized water with using resin in h-form to treated all the divalent and monovalent positive ion where most of these application are conventional onedimensional. linear ion exchange column has been well investigated, and many models have been developed to predict ion exchange performance in vertical flow, however most models assume no axial dispersion model. important to investigated a model that account axial dispersion since the axial dispersion coefficient lumped together all mechanisms leading to axial mixing in packed bed that its account not only for molecular diffusion and conversion mixing but also for non uniformities in the fluid velocity across the packed bed . several workers studied dispersion with porous media, the first who deal with axial dispersion o. levenspiel 1958 when he study the commercial application of step experiment and he design chart to ease the calculation of axial dispersion, h. dunck 1966 study he effect of axial dispersion on the elution band of nonlinear equilibrium chromatography and the effect change in axial dispersion coffin with elution velocity , o .levenspiel 1972 found the c-curve in closed vassal for various extend of back mixing as predicated the dispersion model , c.y. wen, t. tfan l.t. 1975 point that the axial dispersion provides satisfactory description only of mixing model that not deviated significantly from plug flow, r. shinnar 1987emphasized that the application of axial dispersion model for pe no. value for less than 10 is not advised, iman hahider mahdi al-khwarizmi engineering journal, vol. 5, no. 4, pp 1-12 (2009) 2 c. t. tan1987 the value of dispersion coefficient are either assumed or calculated from molecular diffusivity and radial pore velocity prior to incorporation into the model the radial dispersion r. y. a. ofoli, 1991 reported that axial dispersion model is suitable for analysis of reactor up to 30% conversion , y. tsaur and d. shallcross 1997 developed a model to simulate ion exchange performances with fixed annular bed which take into account the radial dispersion in effect in both solution and exchange phases, however the model assumes instantaneous equilibrium between ions in the solution and exchange phases existed throughout the exchanger, m. a. barros and aszpla 2002 analyze the cr +3 ion to exchange in naa zeolite in presence of k + ,cu +3 ion in binary and ternary cation exchange with evaluate the dimensionless variance of breakthrough curve which useful to estimate the axial dispersion of the bed, m. doung and d. shallcross 2002 developed theoretical model of fixed bed ion exchange and obtained the model for pure dispersion without ion exchange performance, i. m. abu-reesh and b.l f. abusharkh 2003 make a comparison of axial dispersion and tank-in-series models for simulating the performance reactors they found that tank-in-series models presents computational advantages compared to dispersion model , doung m. and shallcross d.2005 made a series of experiment in wedge-shape cell ion exchange for both na-and hform bed with different flow rate lead to indicated dispersion coefficient function of pore velocity and radial distant of the wall. 2. dispersion and axial dispersion model dispersion is a general term which is used to describe the various types of self-induced mixing processes occurs during the flow of a fluid through a pipe or vessel. dispersion arise from the effects of molecular diffusion or as a result of the flow pattern existing within the fluid, the important consequence of dispersion is that the flow in a packed bed reactor, the truth that dispersion reflects the back mixing which accurse with flow is a trendy for both axial and radial dispersion since the bed diameter is normally greater than the particle diameter so its comments to have effects of radial dispersion but prevalence of plug and axially dispersed that it can reduce the efficiency of separation. axial dispersion is caused by the twin effects of molecular diffusion and turbulent mixing which a rises from splitting and recombination of flow around the particle therefore it is important to describe the behavior across axial dispersion, the model characterizes mass transfer in axial direction in term of an effective or apparent longitudinal diffusivity dl is superimposed on the plug flow velocity. in order to predicate axial dispersion many assumption are suggest the model assumes that the fluid velocity and reactant concentration are constant across the tube diameter. the magnitude of the dispersion is assumed to be independent of position within the vessel, so there will be no stagnant regions and no by passing or short-circuiting of fluid in the model column also eliminating the assumption of instantaneous equilibrium through the bed by changing the magnitude of the dispersion parameter, one may vary the performance of the reactor from that of plug flow ( ul ld = 0) to that of a single continuous stirred tank reactor ( ul ld =∞). since these two types of phenomena are characterized by a single parameter, and since we force the model to fit the form of fick's law of diffusion, dl should be regarded as an effective dispersion coefficient having the units of an ordinary molecular diffusivity (length 2 /time). however, it is significantly greater in magnitude because of turbulence effects. consider the binary system involving exchange between cations a and b. we assume initially that all the exchangeable sites of the resin bed are in the b-form and the solution phase within the pores of the resin bed is free of cations a. initially, i.e., at t = 0, a solution containing cations a is injected into the top of the resin bed at a volumetric rate, fl, which is constant with time and uniform across the top of the resin bed. the feed solution concentration is constant for t >0 with time. a solution is distributed at a rate uniform across the resin bed. for some time after injection begins, a cations do not appear in the effluent. as the resin gradually converts to the a form, the concentration of a cations in the effluent increases from zero to the feed concentration. plotting the concentration of a cations in the effluent against the produced effluent volume gives the breakthrough curve. the ion exchange process involving a and b cations may be presented by: ar − b b+ + ba a+  bra a+ +a b b+ …(1) where, r is the solid cation exchange resin, a is the valance of a and b is the valance of b and the process is considered reversible. iman hahider mahdi al-khwarizmi engineering journal, vol. 5, no. 4, pp 1-12 (2009) 3 a thin but finite slice of the bed having the thickness ∆z at position z is considered now. for t >0, ca and cra will be volumetric concentration of cations a in the solution phase and in the solid resin phase respectively. ja is the dispersion flux of the a cations. a material balance for a cations over the section may be written as  dt dc za dt dc za ra cb a cb )1(  zzazalzzazacb ccfjja   ()( …(2) in this equation the terms on the left hand side arise from the accumulation of a cations in the solution and resin phases. the first term on the right hand side arises from the dispersion terms and the second results from the convection terms then taking limits as ∆z. →0 z c a f z j t c t c a cb laar b ba             1 …(3) fick’s law can be used to relate the dispersion flux to the concentration gradient: z c dj a la    …(4) where, the axial dispersion coefficient, dlis assumed to be independent of ca and constant with respect to z the substitution of the derivative of the axial dispersion flux into equation (3) yields z c a f z c d c t c a cb la l ra b ba              2 21 …(5) equation (5) is the basic of the theoretical model for ion exchange performance in a fixed bed. several assumptions are implicit in equation (5):  the resin bed is homogeneous with uniform porosity  the bulk phase is plug flow with axial dispersion and mass transfer between phases is accounted for by film diffusion  fluid flows at a rate constant with time, under isotherm condition and is uniformly distributed  the axial dispersion is independent of chemical concentration  the bed is chemically inert and there is no mass transfer in the solid film that ca= cpa r =rp that mean t cra   = 0 …(6) z c a f z c d t c a cb la l a         2 2 …(7) by expressing in dimensionless form equation (7) may be more easily solved u = c l a f , pe= bld ul  …(8) z = (ut + x)/l , θ = t t = tu/ …(9) then equation (7)become z c z c pe c         2 21  …(10) that axial dispersion model is characterized by the pecklet number (pe no.) which can be regarded as the ratio peno.= rate of transport by convection /rate of transport by diffusion or dispersion. axial dispersion model z c z c ul dc lb         2 2  …(11) where the dimensionless group ( ul dl ) is call vessel dispersion number which is measures the extent of axial dispersion where  ul dl 0 negligible dispersion (plug flow)  ul dl ∞ large dispersion (mixed flow) this model represents quite satisfactorily flow that deviates not too greatly from plug flow. equation (11) may be more easily solved using numerical techniques with initial and boundary iman hahider mahdi al-khwarizmi engineering journal, vol. 5, no. 4, pp 1-12 (2009) 4 condition, since the resin is initially in the b-form and the solution within the pores of the bed contains b cations only, the initial condition for the partial differential equation (11) may be written c (0,z) = 0 …(12) at t = 0, there is a step change in the composition of the solution injected into the bed, the boundary conditions that apply to this equation depend on characteristics of the system at the tracer injection and monitoring stations according to these points the bed is assumed as "open," depending on plug flow into the test section that open boundary is one at which the same dispersion parameter characterizes the flow conditions within and adjacent to the test section. there are then three different possible sets of boundary conditions depending on whether a completely open vessel or a closed-open vessel or an open-closed vessel is assumed different solutions will be obtained for different boundary conditions. if we now consider concentration in the feed to an "open" tube that can be regarded as extending to infinity in both directions from the injection point, that the boundary condition are c(θ,0)=1, 2 2 z c   (θ,1) = 0 …(13) the basic method of estimating dl relating the measured mean residence times ( t ) variances pecklet number or dispersion parameter for the test section where ( t ) calculated by the equation (14) ) )( ( 0 dt dt tdf tt    …(14) by using f =c/c0 then determined the variance of the response to a pulse input which is measures the spread of the distribution about the mean defined as       0 0 2 2 )( )( )( dt dt tdf dt dt tdf tt t …(15) where σ 2 t is the variance of the response to a pulse input, in order determination of the reactor dispersion parameter        222 )(8 2 )( ul d ul d t ll t …(16) 3. experimental work a series of experiment were conduct to determined the axial dispersion by examine the breakthrough curve for ion exchange bed using a strong acid resin first with amberlite ir-120styrene-dvb gel type first with na +1 ionic form of a total capacity of 1.9-2.15 meq/ml to treated ca +2 ion in cacl2 solution secondly with same resin type but with h +1 ionic form of 1.8 eq/l total capacity to treated ion in nacl solution. the both kind of resin is packed in a glass column of inside diameter (2.45cm) and (1m)long, the column is packed with 44.5 cm resin bed depth which supported inside the column by a glass disk welded to the wall of the column on the bottom section. fig.1. schemed diagram for the system of experimental work the column is corporate with glass valve of shut of type located to coordinated the different concentration (500,450,350,250 ppm) first with a solution of cacl2 then with a solution nacl of which represent the feed to be treated, a dosing pump with a rotameter is used to control the different flow injected (4, 2, 1.25, 0.9 l/hr) which is connected to the column as down flow operation condition. first with a solution of cacl2 iman hahider mahdi al-khwarizmi engineering journal, vol. 5, no. 4, pp 1-12 (2009) 5 then with a solution nacl six experiment in each feed type were cared, the effluent was collected then analysis using ethylen diamine tetracetic acide (edta) titration method to determined the out put concentration for ca +2 ion and ph value method for determined the out put concentration for na +1 in both type the experiments is continuous until (cout = co) figure (1) show a schemed diagram for the system of experimental work. 4. result 4.1 the breakthrough time the breakthrough time of ca +2 -na +1 exhaustion and na +1 -h +1 runs effected by the cacl2, nacl solution concentration and the flow rate in these curves three zone can be distinguished the first zone is almost saturated where the exist concentration is practically zero then the exchange take places that concentration is increases until the concentration limited value or where it exhausted where the zone is call mass transfer zone which its width measuring the efficiency of ion exchange column, the third zone is almost free of ionic spaces. the result in tables (1) and (2) shows that at high cacl2, nacl solution concentration feed input reducing the breakthrough time and lead the effluent concentration equal to initial concentration in shorter time at the same flow rate and same bed depth because the concentration of ions in the solution increases which raises the mass transfer rate through the film until it exceed the diffusion rate through the resin bed then the diffusion become controlling kinetics which is slower the process , figures (2) and (3) shows the breakthrough curve for different cacl2, nacl solution (500,350,250ppm) at the same flow rate (1.25 l/hr)and same bed depth (44.5cm). table 1, experiments runs for cacl2 salt at cation exchange with naform exp no. salt con. (ppm) flow rate l/hr break-through time(min) tt tu hunb 1 450 4 582 453.75 397.42 12.415 2 450 2 1470 1366.5 1289.74 5.7 3 450 0.9 2310 2183.02 2070.7 5.145 4 500 1.25 540 419.7 361 13.8 5 350 1.25 885 744.74 629.718 15.45 6 250 1.25 972 892.8 779.054 12.7 table 2, experiments runs for nacl salt at cation exchange with h-form exp no. salt con. (ppm) flow rate l/hr break-through time(min) tt tu hunb 1 450 4 400 232.95 125.988 45.92 2 450 2 1080 774.115 364.4 52.925 3 450 0.9 1761 1421.29 1162 18.243 4 500 1.25 300 182.4 122.36 32.92 5 350 1.25 700 504.39 404.65 19.80 6 250 1.25 740 612.4 322.66 47.312 the result in tables (1) and (2) shows that high cacl2, nacl solution flow rate input reducing the breakthrough time and lead the effluent concentration equal to initial concentration also in shorter time at the same concentration and same bed depth that lower flow rate there will be sufficient contact time ions exchanges that the equilibrium is established soon, as the flow rate increases equilibrium is no longer reached and the mass transfer through the film rises until the diffusion through the resin becomes the controlling factor and the system is said to exhibit particle controlled kinetics, figures (4) and (5) shows the breakthrough curve for different cacl2 ,nacl flow rate(4, 2, 1.25, 0.9 l/hr) at the same concentration (450 ppm)and same bed depth (44.5 cm). iman hahider mahdi al-khwarizmi engineering journal, vol. 5, no. 4, pp 1-12 (2009) 6 fig.2. breakthrough time for cacl2 solution at constant (1.25 l/hr) flow rate fig.3. breakthrough time for nacl solution at constant (1.25 l/hr) flow rate fig.4. breakthrough time for cacl2 solution at constant concentration (450ppm) flow rate at constant cacl2 flow rate (1.25 l/hr) 0 0.2 0.4 0.6 0.8 1 1.2 0 500 1000 1500time (min) c /c o ca (500 ppm) ca (350 ppm) ca (250 ppm) constant nacl flow rate (1.25 l/hr) 0 0.2 0.4 0.6 0.8 1 1.2 0 200 400 600 800 1000 time (min) c/ co na (500 ppm) na (350 ppm) na (250 ppm) cnstant cacl2 con.(450ppm) 0 0.2 0.4 0.6 0.8 1 1.2 0 500 1000 1500 2000 2500 3000 time (min) c/ co ca(4l/hr) ca(2l/hr) ca(0.9l/hr) iman hahider mahdi al-khwarizmi engineering journal, vol. 5, no. 4, pp 1-12 (2009) 7 fig. 5. breakthrough time for nacl solution at constant concentration (450ppm) it important to notice that breakthrough time of ca +2 -na +1 exhaustion for cacl2 solution is greater than na +1 -h +1 exhaustion for nacl solution in the same condition of salt concentration and flow rate that the exchange of divalent with monovalent can go much completely because the concentration of the monovalent ions is squared in ca +2 -na +1 exchange that effected on the selectivity of the resin with taking in a count the decreasing of size of hydrated ions from na +1 to ca +2 which make the exchange capacity for divalent ions is grater than for monovalet ion . the time equivalent to usable capacity (tu) and the time equivalent to total stoichiometric capacity of packed bed (tt) if the entire bed attains to equilibrium are easily to determined by eq. (17) where tb is the time related to c = 0.05co …(17) the length of unused bed is determined by equation (18) that (tu/tt) is the fraction of the total bed capacity or length utilized to the breakpoint. l t t h t u unb        1 …(18) where l is the total bed length the hunb values is listed in tables (1)and(2) for cacl2 and nacl ion exchange operation solution at different feed concentration and different flow rate that the small value means that the breakthrough curve is close to an ideal step with negligible mass transfer resistance. it can be notice that hunb depends on concentration of the ion to be exchange, ions types, the temperature and fluid velocity while it independent of column length which allows the design and scale-up from small scale laboratory to be determined that the full-scale column obtained by simply adding the hunb to the length of bed needed. it's important to taken into account the axial dispersion because differences in the extent of axial dispersion in small-scale laboratory and fullsize column may caused discrepancies. 4.2 axial dispersion residual time axial dispersion for ca +2 -na +1 and na +1 -h +1 ions exchange is calculated and listed in tables (3) and (4), the values of dispersion number for ca +2 -na +1 and na +1 -h +1 exhaustion is increasing with increasing flow rate at the same salt concentration that at height flow rate the bed is consist of a series of mixing cell the dimension of each of which is of the same as the size of the bed particles forming while at low flow rate the effect of molecular diffusion predominate and the cell mixing contributes relatively little to dispersion. for ca +2 -na +1 figure(6) show small extend of dispersion ( ul dl <0.01) which mean small deviation from plug flow that the spreading tracer curve does not significantly change in shape as it passes( during the time it is measuring it)which gives symmetrical curves.    0 )1( dt c c t o t  bt o u dt c c t 0 )1( constant nacl con.(450) 0 0.2 0.4 0.6 0.8 1 1.2 0 500 1000 1500 2000 time (min) c/ co na(4l/hr) na(2l/hr) na(0.9l/hr) iman hahider mahdi al-khwarizmi engineering journal, vol. 5, no. 4, pp 1-12 (2009) 8 table 3, experiments runs for cacl2 solution at cation exchange with naform exp no. salt con. (ppm) flow rate l/hr residence time (min) αө 2 ul dl dl pe no. 1 450 4 449.4 0.145 0.0588 77.36 45.98 2 450 2 1453.19 0.0306 0.0145 9.538 229.885 3 450 0.9 2291 0.00596 0.00294 0.87 1133.78 4 500 1.25 441 0.0878 0.00432 1.806 771.6 5 350 1.25 756.05 0.00726 0.00358 1.47 915.36 6 250 1.25 899.18 0.00294 0.00145 0.596 2298.85 table 4, experiments runs for nacl solution at cation exchange with h-form exp no. salt con. (ppm) flow rate l/hr residence time (min) αө 2 ul dl dl pe no. 1 450 4 273.959 0.296 0.1044 137.359 31.928 2 450 2 841.03 0.1514 0.061 40.125 54.64 3 450 0.9 1684.92 0.0066 0.0295 8.79 112.765 4 500 1.25 195.966 0.0239 0.01145 4.707 291.12 5 350 1.25 516.316 0.017 0.00824 3.387 404.53 6 250 1.25 659.88 0.035 0.01648 6.7757 74.57 fig.6. axial dispersion for cacl2 solution at constant flow rate (1.25l/hr) but with na +1 -h +1 ion exchange figure (7) show small extend of dispersion ( ul dl >0.01) which mean small deviation from plug flow that resulting s-shape response curves is not symmetrical that mean the flow is undistributed as it passing the entrance and exit boundaries .  ul dl 0 ul dl iman hahider mahdi al-khwarizmi engineering journal, vol. 5, no. 4, pp 1-12 (2009) 9 fig.7. axial dispersion for nacl solution at constant flow rate (1.25l/hr) the values of vessel dispersion number for ca +2 -na +1 and na +1 -h +1 is increasing as the cacl2 , nacl salt concentration increasing for the same flow rate as shown in tables (3) and (4)that when concentration differences exist the rate of transfer(exchange) is proportional to the product of the molecular diffusivity and the concentration gradient where the fluid at centre moves with twice the mean velocity this can rise the dispersion since elements of fluid will take different times to traverse the length of the column. figures (8) and (9) show small extend of dispersion ( ul dl <0.01) which mean small deviation from plug flow for ca +2 -na +1 and na +1 h +1 ion exchange. the dimensionless variances of breakthrough curve is calculated and listed in table (3) and(4) for the both case of ion exchange(ca +2 ,na +1 ) that it value of σ 2 ≈ 0 means the packed bed close to an ideal flow reactor with negligible axial dispersion fig.8. axial dispersion for cacl2 solution at constant concentration (450ppm)  ul dl 0 ul dl  ul dl 0 ul dl iman hahider mahdi al-khwarizmi engineering journal, vol. 5, no. 4, pp 1-12 (2009) 10 fig.9. axial dispersion for nacl solution at constant concentration (450ppm) pe no. represent all of the effects that cause deviations from ideal plug flow behavior such as nonuiform velocity profiles or eddies listed in table (3) and(4) for the both type ion exchange (ca +2 ,na +1 ) its mean increasing as the flow rate increasing and decreasing with increasing (nacl,cacl2) salt concentration that as pe no. increasing from 0 to ∞ the flow pattern in the column changes from complete mixing (cstr) to no mixing, with low pe no. high conversion with low residence time accurse because molecular diffusion strongly effects the rate of dispersion in laminar flow means at low flow rate it promotes dispersion but at higher flow rate it has opposite effect . 5. conclusion a mathematical model has been developed to simulate ion exchange with fixed bed; the axial dispersion model is applied with experimental observation for both ca +2 and na +1 ion in cation exchange column. the breakthrough time is decreasing with increasing flow rate and feed concentration and its greater for divalent ions from monovalent ions. the axial dispersion model show small extend from plug flow for ca +2 ions exchange both exchange in both increasing flow rate and increasing salt concentration while its show large extend from plug flow for na +1 ions with increasing flow rate and salt concentration. nomenclature a valence of cation a ac circular cross-sectional area b valence of cation b cstr continuous stirrer tank reactor c a solution phase concentration cra resin phase concentration c0 total normality in the solution csa surface phase concentration in particle cpa pore phase concentration in particle dl solution phase dispersion coefficient d column inner diameter εb bed porosity f c/c0 fl flow rate hunb length of unused bed ja dispersion flux of a cations in s o solution l bed length pe peclet number θ dimensionless time r solid cation exchange resin rp resin radius t time t mean residence times tb time related toc = 0.05co tt time equivalent to total stoichiometric  ul dl 0 ul dl iman hahider mahdi al-khwarizmi engineering journal, vol. 5, no. 4, pp 1-12 (2009) 11 capacity tu time equivalent to usable capacity u velocity for linear flow z dimensionless column distance σ 2 t variance of the response to a pulse input 6. references [1] bros a. s. d. and zola a. s., 'binary and ternary dynamic cation exchange naa' universidade estadual maringa conference, 2002, colombo av/petrobras, rio de janero-rj-barazil [2] crittenden b., thomas w.j. 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'use of residence and contact time distribution in reactor design' in chemical reaction and reactor engineering,carberry,newyork,1987 [19] scoop r. 'slow piratical diffusion ion exchange column', i&ec fundamental vol. 4,no.30 august 1956 [20] ofoli r. y. a. and komolprasert v. 'dispersion model for predicating the extent of starch liquefaction', biotechnolbioegn., 1991, 37 ,681-690 [21] qasim s. r., motly e. m. and zhu g., 'water works engineering', prentic-hall of india, 2006 [22] maccabe w., smith j. c. and harriott p., 'unit operation of chemical engineering' seven edition, chemical engineering series mccrow-hill, 2005 [23] tsaur y. and shallcross d. c., 'molding of ion exchange performance in fixed radial flow annular bed', ind. eng. chem. res. 1997, 36, 2359-2367 12-1، صفحة 4 ، العذد 5 مجلة الخوارزمي الهىذسية المجلذ ايمان حيذر مهذي (200 9 ) 12 دراسة التشتث المحوري لعمود الطبقة الثابته مه المبادالت االيووية ايمان حيذر مهذي جايؼة انُٓسيٍ / كهية انُٓدسة/ قسى انُٓدسة انكيًيأية الخالصة جى جطٕيس يٕديم زياضي نٕصف اداء ػًٕد اسطٕاَي َٕع انطثقة انثاتحّ يٍ انًثادالت االيَٕية يحضًٍ يقازَة يٕديم انحشحث انًحٕزي تؼدد يٍ . انفسضيات حيث اٌ ْرا انًٕديم يسًح تححيد االداء نهؼًٕد ٔ حساب انٕقث انًقيى نححديد االَحساف ػٍ ػًٕد انجسياٌ انًضغٕط نيحثادل يغ زشٌ تصيغة ايٌٕ (ايٌٕ انكانسيٕو انًٕجة ) جى اخحياز ًَٕذجيٍ يٍ اَظًة انحشغيم ناليَٕات انًٕجثة جى انؼًم أال يغ ايَٕات ثُائية انحكافؤ نيحثادل يغ زشٌ تصيغة ايٌٕ انٓيدزٔجيٍ ٔانري (ايٌٕ انصٕديٕو انًٕجة)انصٕديٕو ٔانري يطثق تٕحدات انًاء انسائق ٔانثاَي يغ ايَٕات احادية انحكافؤ . يطثق في ٔحدات انًاء اناليَٕي جى اخحياز ػايهيٍ نكم ٔاحد يٍ انُظاييٍ ًْا اخحالف يؼدل جسياٌ انًغري ٔاخحالف جسكيص انًهح ػٍ طسيق جاثيسْى في انحشحث انؼًٕدي نكم حانة انصيٍ انًكافئ نهسؼة انًسحؼًهة ٔانصيٍ انًكافئ نسؼة االجصاٌ )تٕاسطة يقازَة االداء ٔانري يؼثس ػُّ تصيٍ االسحُصاف حيث جى حساب يحددات اخسٖ حسثث خالل ظسٔف انؼًم الٌ ْرِ انًحددات يغ انحشحث انًحٕزي يًٓة جدا نححديد افضم ظسٔف نحشغيم ػًٕ د انطثقة (ٔطٕل انؼًٕدٖ غيس انًسحؼًم . انثاتحّ نهًثادل االيَٕي انًٕجة كٕحدات انًاء انسائق ٔٔحدات انًاء اناليَٕي 55 al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 5, no. 4, pp 51-57 (2009) improve akaike’s information criterion estimation based on denoising of quadrature mirror filter bank mohammed h. miry department of electrical and electronic engineering/ university of technology (received 1 febreuary 2008; accepted 17 september 2008) abstract akaike’s information criterion (aic) is a popular method for estimation the number of sources impinging on an array of sensors, which is a problem of great interest in several applications. the performance of aic degrades under low signal-to-noise ratio (snr). this paper is concerned with the development and application of quadrature mirror filters (qmf) for improving the performance of aic. a new system is proposed to estimate the number of sources by applying aic to the outputs of filter bank consisting quadrature mirror filters (qmf). the proposed system can estimate the number of sources under low signal-to-noise ratio (snr). keywords: akaike’s information criterion (aic), quadrature mirror filters (qmf). 1. introduction the quadrature mirror filters (qmf) has diffused into most signal processing applications. it plays a very important role in the denoising of signals since it gives an effective, informative and compact description of the analyzed signals. in 1988, mallat produced a fast wavelet transform. the mallat algorithm for discrete wavelet transform (dwt) is known as quadrature mirror filters (qmf) [1-3].this property also endows wavelets with a remarkable aptitude for denoising by means of a simple nonlinear thresholding filter. mallat and hwang first showed that effective noise suppression may be achieved by transforming the noisy signal into the wavelet domain by qmf, and preserving only the local maxima of the transform. a wavelet reconstruction that uses only large-magnitude coefficients has also been shown to approximate well the uncorrupted signal; in other words, noise suppression is achieved by thresholding the wavelet transform of the contaminated signal. the problem of estimating the number of sources impinging on a passive array of sensors has received a considerable amount of attention during the last two decades. the first to address this problem were wax and kailath. in their seminal work it is assumed that the additive noise process is a spatially and temporally white gaussian random process. given this assumption, the number of sources can be deduced from the multiplicity of the received signal correlation matrix’s smallest eigenvalue [4]. in order to avoid the use of subjective thresholds required by multiple hypothesis testing detectors, wax and kailath suggested the use of the akaike’s information criterion (aic)[5] for estimating the number of sources. the aic estimator can be interpreted as a test for determining the multiplicity of the smallest eigenvalue [5], but its response degrades under low signal to noise ratio (snr) condition due to errors in estimation the data covariance matrix from finite data. in this paper, a new system is proposed to determine the number of sources using aic and qmf bank. the method can estimate the number of sources under low snr environment. 2. quadrature mirror filter quadrature mirror filters (qmf) is the mallat algorithm for discrete wavelet transform (dwt), it analyses a finite-length time-domain signal at mohammed h. miry al-khwarizmi engineering journal, vol.5, no. 4, pp 51-57 (2009) 52 different frequency bands with different resolutions by successive decomposition into coarse approximation and detail information as shown in fig (1). approximations represent the slowly changing features of the signal and conversely details represent the rapidly changing features of the signal. the impulse response of the decomposition and reconstruction qmf pairs are related by[6] )1()1()( 1'   nhnl n )1()1()( 1'   nlnh n …(1) where h(n) and l(n) are the low-pass and the highpass fir filters of decomposition qmf and h ' (n) and l ' (n) are the low-pass and the high-pass fir filters of reconstruction qmf. the decomposition level of qmf bank is denoted by m (select a suitable number of levels based on the nature of the signals, or on a suitable criteria such as entropy). the wavelet de-noising approach is based on the assumption that random errors in a signal are present over all the coefficients while deterministic changes get captured in a small number of relatively large coefficients. as a result, a nonlinear thresholding (shrinking) function in the wavelet domain will tend to keep a few larger coefficients representing the underlying signal, while the noise coefficients will tend to reduce to zero. practically, the wavelet denoising method consists of applying the qmf bank to the original noisy data, thresholding the wavelet coefficients, and then inverse transforming the thresholded coefficients to obtain the time-domain de-noised data [7]. it should be noted that the performance of the wavelet de-noising depends to the choice of the thresholding rule, the type of wavelet, the maximum depth of wavelet decomposition and the initial snr. in this paper, we use soft thresholding method to eliminate noise from noisy data. according to soft thresholding method, the wavelet coefficient between -δ and δ is set zero [8], while the other are shrunk in absolute value. the threshold δ proposed by donoho is )log(2 n  …(2) where n is the total number of samples and σ is the standard deviation of noise. in order to apply this method in practice, one usually needs to estimate σ. donoho & johnstone suggest using as an estimator the median of the coefficients on the finest level divided by 0.6745 which usually works well as long as the signal is contained mainly in the low frequency coefficients [8]. 2 2 2 a1 fig.1. structure of the qmf bank. s = signal, l = low-pass decomposition filter; h = high-pass decomposition, l' = low-pass reconstruction filter; h' = high-pass reconstruction filter filter; = down-sampling operation, = up-sampling operation. a 1 , a 2 are the approximated coefficient of the original signal at levels 1, 2 etc. d 1 , d 2 are the detailed coefficient at levels 1,2. a 1 ', a 2 ' are the processed or non-processed approximated coefficient of the original signal at levels 1, 2 etc. d 1 ', d 2 ' are the processed or non-processed detailed coefficient at levels 1,2. 2 2 analysis decomposition synthesis reconstruction original signal level 1 level 1 level 2 level 2 reconstructed signal 2 2 2 2 2 a2 d2 d1 d1' d2' a2' a1' mohammed h. miry al-khwarizmi engineering journal, vol.5, no. 4, pp 51-57 (2009) 55 3. aic principle the array model assumes the presence of q sources impinging on an p-channel array according to [9] zasy  …(3) where npy  denotes the multichannel observations in the sampled time interval ntt  , where n is an integer, qpa  denotes the mixing (steering) matrix, nqs  denotes the source signal matrix, and npz  denotes an additive gaussian noise component with nontrivial temporal and spatial covariance matrices. it will be assumed that within the n snapshots consisting the analysis window, no more than pq  sources is present. the matrix s is full rank when all the q sources are independent. when s is rank-deficient, this usually means that either the source signals have correlated waveforms, or subsets of the signals are perfectly coherent, i.e., at least one of the signals is just a scaled and delayed version of another signal. this type of situation arises when the multipath phenomenon occurs, i.e., a direct signal path and one or more indirect paths are received by the array in which case the signals are not independent. on the other hand, the columns of the matrix a represent the array response due to each of the q signals impinging on the array. each column depends only on the geometrical construction of the array and the directional response of the sensors. generally speaking, if the array is properly designed and the sources are independent and treated as point sources, a will be full rank. a can also be rank deficient when the propagating medium has nonstationary characteristics, or in some sense anisotropic. this situation can very likely arise in a neurophysiological experiment. first, consider the noise free observations given by the product matrix x = as. if a or s has rank less than q, x will also have rank less than q. if there are q ≤ p ≤ n independent rows in x, then this matrix is said to have a p-dimensional range or row space, which is a subspace of the m-dimensional euclidean space ℜm . the rank of this matrix is the dimension of this subspace. the spatial covariance of x when spectrally factored yields   t xxx t x uduxxer .. …(4) where pp xd  is a diagonal matrix containing the rank ordered eigenvalues 0.................. 121   pqq  o f rx. if there are q signal sources, the largest q eigenvalues correspond to the q sources and the first q columns of the unitary matrix ux span the signal subspace. the remaining p-q eigenvalues are equal to zero with probability one. in practice, the finite sample size and the presence of noise amount to estimating the sample eigenvalues 0.................21  pq  from the sample covariance matrix [10-11]     1 0 ][][ 1 n n t y nyny n r …(5) the remaining p-q eigenvalues are no longer equal to zero and the corresponding p-q eigenvectors span the noise subspace. when the noise is cross correlated with the signal of interest, ry can be expressed as t zsszz t sy ararraarr  …(6) where sr is the autocorrelation of signal, zr is the autocorrelation of noise, szr is the crosscorrelation between the signal and noise and zsr is the crosscorrelation between the noise and signal. the presence of the cross covariance terms shrinks the separation distance that should be observed to determine the subset of eigenvalues belonging to the signal subspace because of the mutual correlation of the sample eigenvalues, making it practically impossible to determine q. in good snr conditions, the separation between the signal and noise subspaces is easily obtained. in low snr conditions, this separation does not yield easily and the source detection problem amounts to the so-called sphericity test to determine the multiplicity of the smallest p-q eigenvalues using the akaike’s information criterion (aic) [5]    kpk l kp l kaic p ki i p ki kp i                     22 1 log2 1 1 )/(1 …(7) where il denote the eigenvalues of ^ r . the number of signals is taken to be the value of  1,......,1,0  pk for which aic is minimized. mohammed h. miry al-khwarizmi engineering journal, vol.5, no. 4, pp 51-57 (2009) 54 4. proposed model figure 2 shows the block diagram of the proposed system to estimate the number of sources. the main procedure of the system is described as follows. first, the signals are received by antennas. next, these signals are processed by the qmf bank. then, in every bank, the channel that exceeds threshold level (δ) as compared with other channels will be chosen at the selection unit. the selected channel’s output data is applied to idwt (inverse of discrete wavelet transform). the output of idwt is used to compute its covariance matrix. finally aic is calculated to estimate the numbers of sources. wp,m qmf qmf qmf y1(t) y2(t) yp(t) ……. ……. ……. ……. ……. w1,1 w1,m wp,1 antenna 1 m.m, antenna 2 m.m, antenna p m.m, w2,1 w2,m w1,2 w2,2 wp,2 covariance matrix computation inverse of discrete wavelet transform selection unit w1,m w2,m wp,m aic estimation the number of the sources fig.2. block diagram of the proposed system. ……. ……. where m = 1, 2, 3, …..., m fig.3. structure of the selection unit. wl ,m w2, m wp,m threshold level threshold level threshold level . : gate switches where m = 1,2,…., m mohammed h. miry al-khwarizmi engineering journal, vol.5, no. 4, pp 51-57 (2009) 55 4.1. selection unit figure 3 shows the structure of selection unit. the role of the unit is to select the channel that exceeds threshold level (δ) as compared with other channels. in every bank, the soft threshold is applied to the output of qmf bank. the gate switches are simultaneously closed when the output of qmf banks exceeds threshold level (δ) table 1, the response of the aic method with two sources k 0 1 2 3 4 5 6 7 classical system aic(k) 1505.5 25.7 * 31.6 114.6 225.9 389.8 703.5 1615.9 modified system aic(k) 1875.4 87.7 41.1 * 49.1 171.3 353.5 703.5 1724.8 * refers to the minimum value table 2, the response of the aic method with three sources k 0 1 2 3 4 5 6 7 8 9 10 classical system aic(k) 1371.1 96.4 29* 98.2 190.6 280.4 368.1 455.8 541.2 625.6 710.2 modified system aic(k) 19451.5 263.7 157.3 38.6* 124.4 411.2 1204.1 1637.3 1872.1 1017.5 791.9 table 2, continue k 11 12 13 14 15 16 17 18 19 20 21 classical system aic(k) 811.2 903.5 1004.8 1120.1 1255.6 1431.3 1673.9 2077.0 2816.4 4978.5 5816.3 modified system aic(k) 682.0 619.7 581.3 558.1 544.5 537.7 536.5 539.9 547.2 557.7 554.3 * refers to the minimum value 5. simulation and results in order to compare the performance of the above proposed system with classical system (without applying proposed model for aic method), we consider two cases with different values for snr, the number of sources and direction of arrival for the sources. the first case, a uniform linear array (ula) of 8 sensors is consider with a half-wave length inter-element spacing, used to separate two uncorrelated emitters based on a batch of n=100 data samples with snr=13 db. the first source is at 50 o while the second source is at 55 o . it is noticed the response of classical system shown in table(1), the minimum value of aic is obtained incorrectly for k = 1. the parameter are used in proposed system include daubechies wavelet (db18) and one level decomposition, the response of proposed system shown in table (1), the minimum value of aic is obtained correctly for k = 2. the second case, a uniform linear array (ula) of 22 sensors is consider with a half-wave length inter-element spacing, used to separate three uncorrelated emitters based on a batch of n=100 data samples with snr= 2 db. the first source is at 50 o , the second source is at 52 o , while the third source is at 54 o . it is noticed the response of classical system mohammed h. miry al-khwarizmi engineering journal, vol.5, no. 4, pp 51-57 (2009) 56 shown in table (2), the minimum value of aic is obtained incorrectly for k = 2. the response of proposed system shown in table (2), the minimum value of aic is obtained correctly for k = 3. through comparison between the responses of classical system with the responses of proposed system, it is seen that the first does not yield the correct number of the sources but the proposed model gives the correct number of the sources as seen in table (1) and table (2). 6. conclusion in this paper, we have introduced a new system to determine the number of sources by applying aic to the outputs of filter banks consisting qmf. in the paper, the classical system and proposed system are compared through simulation. the proposed method can give good estimation for the number of the sources even if low snr environment while the classical system is fail under low snr. the qmf in proposed model helps to reduce the error of the array data covariance estimated from finite data and thus reduce the error of the aic estimation. 7. references [1] a. kumar, g. k. singh, and r. s. anand, "near perfect reconstruction quadrature mirror filter", proceedings of world academy of science, engineering and |technology volume 27 february 2008 issn 1307-6884. [2] d. estaban and c. galand, “application of quadrature mirror filters to split band voice coding scheme,” in proc. ieee icassp, 1997, pp. 191–195. [3] c. tsai, "analysis of complex quadrature mirror filter banks", proceeding of world academy of science, engineering and |technology volume 13 february 2006 issn 1307-6884. [4] m. kaveh, h. wang, and h. hung, “on the theoretical performance of a class of estimators of the number of narrow-band sources,” ieee trans. on acustic speech and signal processing, vol. assp-35, no. 11, pp. 1350–1352, 1987. [5] f. ridder, r. pintelon, j. schouken and d. gillikin, "modified aic and mdl model selection criteria for short data records" ieee trans. on instrumentation and measurement, vol. 54 , no. 1, february 2005. [6] a. bal, "wavelet denoising for geophysics images", international conference on earth sciences and electronics-2002 (icese-2002) pp. 165-170 [7] u. e. emir, c. b. akgül and a. akın, "wavelet denoising vs ica denoising for functional optical imaging", proceedings of the 1st international ieee embs, conference on neural engineering, capri island, italy, march 20-22, 2003. [8] d. l. donoho, “de-noising by softthresholding,” ieee trans. inform. theory, vol. 41, pp. 613-27, 1995. [9] e. fisher, m. grossman, and h. messer, “estimation the number of sources using information theoretic criteria general performance analysis”, ieee trans. on signal processing vol. 50, pp. 1026-1035, may 2002 [10] m. cedervall and l. moses "efficient maximum likelihood doa estimation for signals with known waveforms in the presence of multipath", ieee tran. on signal processing, vol. 45. no. 3, march 1997. [11] t. ayoub and a. haimovich, "modified glrt signal detection algorithm" ieee tran. on aerospace and electronic systems vol.36 no. 3, july 2000. 5751 ، صفحة 4 ، العذد 5محمذ حسٍن مري مجلة الخوارزمً الهنذسٍة المجلذ (2009) 57 لحسمة أزالة التشوٌه باألعتماد علىakaikeمعٍار معلومات تطوٌر تخمٍن مرشح مربع المرأة محمذ حسٍن مري الجبهعت التكٌىلىجٍت/ قسن الهٌذست الكهزببئٍت و األلكتزوًٍت الخالصة والتً تعتبز ههوت فً العذٌذ هي , هً طزٌقت هعزوفت لتخوٍي عذد الوصبدر الوزتطوت بٌظبم الوتذسسبث akaike (aic)هعٍبر هعلىهبث هذا البذث هختص بتطىٌز و تطبٍق هزشخ هزبع . واطئت(snr) تصبخ سٍئت عٌذهب تكىى ًسبت األشبرة الى التشىٌه (aic)اى أستجببت طزٌقت .التطبٍقبث على ًتبئج دزهت هزشخ ٌذتىي على (aic)ًذي أقتزدٌب ًظبم جذٌذ لتخوٍي عذد الوصبدر بىاسطت تسلٍط . (aic) لتذسٍي استجببت(qmf)الوزأة . واطئت(snr)الٌظبم الوقتزح ٌستطٍع تخوٍي عذد الوصبدر عٌذهب تكىى ًسبت األشبرة الى التشىٌه . (qmf)هزشخ هزبع الوزأة al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 6877 (2014) experimental performance of a finned-tube silica gel adsorption chiller for air-conditioning application mohammed a. atiya* farkad a. lattieff** adil a. al-hemiri*** *dean of alkhwarizmi college of engineering / university of baghdad **research & development department / ministry of higher education ***department of environment / collage of engineering / university of baghdad *email: mohatiya1965@gmail.com **email: farkad400@yahoo.com ***email: hemiri2004@gmail.com (received 21 may 2014; accepted 12 october 2014) abstract this work presents the construction of a test apparatus for air-conditioning application that is flexible in changing a scaled down adsorbent bed modules. to improve the heat and mass transfer performance of the adsorbent bed, a finned-tube of the adsorbent bed heat exchanger was used. the results show that the specific cooling power (scp) and the coefficient of performance (cop) are 163 w/kg and 0.16, respectively, when the cycle time is 40 min, the hot water temperature is 90 o c, the cooling water temperature is 30 o c and the evaporative water temperature is 11.4 o c. keywords: adsorption, refrigeration, cooling power, cop, silica gel-water. 1. introduction energy is the main driver for the well being, development and quality of life for people. nowadays, the strength of countries depends on the extent of diversification of energy that they get it. it is no longer limited to oil as principal source of energy but diversified to include many sources of energy, called renewable energy [1].electricity consumption on air-conditioning results in a shortage of the rush of electricity in summer [2]. in addition, the usage of cfcs and hcfcs in traditional air-conditioning systems causes the ozone depletion and green house effects [2]. due to the large consumption for airconditioning systems in building, solar cooling systems have attracted great attention nowadays [2]. there are many researches about adsorption air-conditioning. for example, in order to improve cop, c.j. chen and his co-workers have adopted a heat and mass recovery by installing vacuum valves between the adsorption and desorption chambers of the adsorption chiller [3]. however, silica gel-water adsorption chillers are welcomed for the solar air-conditioning systems and widely studied [4]. kahan et al. studied the influence of the overall thermal conductance of the sorption elements and evaporator as well as the adsorbent mass on the chiller performance and indicated that the cycle performance strongly influenced by the overall thermal conductance of the sorption elements [5]. generally, a heat source with 70-80 o c is economical for silica gelwater adsorption chiller and easily obtained from solar energy or waste heat [6]. demir et al. handled the mechanism of heat and mass transfer in annulus adsorbent with which shows that the adsorption period increases with increase the porosity value [7]. al sapienza et al. investigated a new composite adsorbent and tested it by a labscale adsorption chiller. they observed that the optimal cycle time performance was strongly depended on cycle time and relative duration of the isobaric desorption and adsorption steps [8]. aristov et al. investigated, using an intermittent cycle, the effect of the relative duration isobaric mailto:mohatiya1965@gmail.com mailto:farkad400@yahoo.com mailto:hemiri2004@gmail.com mohammed a. atiya al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 6878 (2014) 69 adsorption/desorption stages to maximize the coefficient of performance and the specific cooling power of the cycle. they found that the desorption phase is faster than the adsorption one and this should considered as a routine case for adsorption refrigeration cycle, probably, because adsorption occurs at higher temperature and pressure and hence, they suggested practical recommendation to rationally reallocate the duration of adsorption and desorption phases [9]. a newly developed adsorption chiller was described and tested by liu et al. in this adsorption cycle system, there is no refrigerant valve. thus, the problem of mass transfer resistance was eliminated. the experimental results proved that it is able to produce a cooling capacity of 6.5 kw with cop of about 0.4[10]. to demonstrate the effect of mass and heat transfer on the scp and cop, a laboratory prototype of adsorption cooling machine has been designed by wang and his team. experiments showed that the cop was between 0.2-0.4 for refrigeration temperature of -10 to -15 o c depending on the cooling water temperature. the scp ranges from 300-500 w/kg adsorbent [11]. in order to improve the reliability of silica gelwater adsorption chiller, chillers combined by two bed cooling systems were modified. the recent results [12] were that the cooling capacity and cop of such chiller were 3.6 kw and 0.32, respectively, at the hot water inlet temperature of 57 o c, cooling water temperature of 27 o c,and chilled water temperature of 15 o c; those were up to 5.7 kw and cop of 0.41, respectively, when the hot water inlet temperature, cooling water temperature, were changed to 80 o c and 29 o c, respectively. those investigation had resulted in closer steps to commercial prototypes thought so far those prototypes were not really commercial once due to its high cost [13]. a novel composite dsorbent “silica gel modified by calcium nitrate” (sws-l8) for utilization in adsorption chillers driven by low temperature heat has tested by freni et al. sws-8l grains were embedded inside aluminium heat exchanger with high thermal efficiency. experimental cooling cop, specific cooling power scp and volumetric specific cooling power vscp obtained were 0.18-0.31 (cycle time 10 min), 190-383 w/kg dry sorbent and 104-212 w/dm 3 , respectively [14]. miyazaki et al. investigated the influenced of heat exchanger parameters, such as heat capacity and ntu, on the optimum performance of a singlestage adsorption chiller using silica gel as a working pair. he concluded that the smaller heat capacity improved both the scp and cop. while the large ntu of the adsorbent bed resulted in the decrease of cop due to the short cycle time although the maximum scp was enhanced [15]. niazamand and dabadeh analyzed the effect of the bed configuration, such as fins spacing, bed high, and particle size high on the performance of the system. they showed that fins in general reduced the cop of the system; however, for a given cooling capacity cp, the bed size can be reduced dramatically, when fins were employed at the cost of slightly lower cop. also, it is shown that there is an optimal particle diameter associated with each bed configuration that maximizes the cop and scp [16]. in this work, a fine-tube silica gel-adsorption chiller for air-conditioning application built in order to generate cooling energy and evaluate the cooling output performance. the experimental data evaluated in terms of cooling output (or specific cooling power scp) and coefficient of performance cop. this study will benefit the further application and development of the solar adsorption air-conditioning system. 2. description of the prototype the optimization of the refrigeration adsorption cycle conducted at the solar energy laboratory / federal university of paraiba by the use of a labscale facility realized to the support the development of the solar adsorption chiller. fig. 1 (a) shows the schematic diagram of the experimental adsorption chiller prototype. the adsorption chiller has a single bed, a condenser, an evaporator and heating/cooling water system. the evaporator lies at the bottom of the chiller, and the condenser is located at the top of the conditions and operating adsorption cycles. the whole prototype connected to a water heating system, for refrigeration, tape water for cooling, and a vacuum pump system. the heating system is next to the adsorber. all the valves controlled manually. the prototype designed to test various operations. two main parameters measured during the experiment: temperature and pressure. all sensors connected to a data logger and recorded every 8.5 seconds. the data measurements taken after the cycle steady has been reached. a computer used to collect and process the data measurement acquired by the data logger. the flow rate of the hot water and cooling water are constant at 0.4 kg/s. the adsorber is of a shell-and-tube configuration, which readily manufactured, and it withstand high operating pressure and incur low energy mass. mohammed a. atiya al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 6878 (2014) 70 using fins and tubes design, (fig. 1 (b)), made the surface area to volume relatively low. the fins on the adjacent tube overlap slightly in order to reach all the portions of the shell voids. they allowed tubes to be more widely spaced to accommodate greater proportion of adsorbent. furthermore, the fins have several times a wider surface area than the bare tube, which counter the low conductance through the contact between the metal and the adsorbent. this design has 905 m 2 surface area / m 3 volume. the main properties are resumed in table. 1. 3. measurements the experimental conditions are stated in table. 2. the temperature are measured at the inlet and outlet of the heat exchanger of the adsorber during cooling and heating periods. the pressures are measured at the adsorber. the amount of the desorbed water, , are measured by the level graduated cylinder. the performance evaluation of the adsorption chiller is calculated from the terms of cooling power [w], specific cooling power scp [w/kg] , and coefficient of performance cop, which are calculated as follows: …(1) …(2) …(3) …(4) table 1, main properties of the adsorber bed. table 2, prototype experimental conditions. property value unit total mass of adsorbent grain size 4 7 kg mm tube length 0.5 m number of tube 4 inside tube diameter 0.017 m outside tube diameter fin diameter fin space 0.19 0.05 0.008 m m m parameter value unit mohammed a. atiya al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 6878 (2014) 71 c (a) (b) fig. 1. schematic of experimental adsorption chiller (a), adsorber (b) 4. results and discussion 4.1. temperature profile of system as the driving forces, the hot water inlet temperature is very important to the adsorption refrigeration system. a high water temperature causes a large temperature lifts for the system at the same cooling temperature. then, the larger temperature lifts results in a high refrigeration capacity. fig. 2 illustrates the cycle variation of the adsorbent temperature with inlet hot water temperature of 90 o c (with constant cooling water of 30 o c) in the adsorber heat exchanger packed with silica gel grains. fig. 2 also shows that, the temperature effectiveness of the adsorbent element’s capability to exchange sensible heat is based on the actual and maximum temperature difference. this difference decreases with time. according to this figure, the bed temperature rises sharply before the 10 mins, but after 20 mins this temperature difference becomes small. the reason of this small difference is the water vapour releases from the silica gel grains. after 60 mins, this difference reduced to a very small value. fig. 3 shows the temporal evolution of the isosteric cooling, isosteric heating, desorption and adsorption phases at a steady state for the following operating conditions concluded from the experiment test (table 2). it is observed that during the isostering cooling, the temperature of the bed will decrease from 90 o c to 62 o c (blue linear line) at after this moment the valve between the adsorber and the evaporator will open until the temperature of the adsorbent bed becomes 35 o c (blue curve line). after elapsed of 20 mins, the isostearing heating will start and the temperature of the adsorbent bed increases from 35 o c to 62 o c (red linear line), then the valve between the condenser and the adsorber will open for desorption process until the temperature becomes 90 o c again (red curve line). silica gel metal screen cooling water data logger cylinder condense r vapor hot water out pressure transducer hot water in heating water device device pressure transducer transducer evaporator condenser r shell l adsorber wir silica gel computer mohammed a. atiya al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 6878 (2014) 72 fig. 2. isosteric heating/cooling cycles. fig. 3. cycle time of the system. 4.2. refrigerant exchange amount ( ) desorptoin process is very close in concentration change to adsoption process at the same temperature, and many researches assume both are the same in adsorption refrigeration process [17] . working on the temperature of 90 o c tends to decrease the water content to the minimum and, consequently, it results in increasing the water adsorbed during the adsorption process and that increases the cooling capacity. fig. 4 aims to determine the desorbed water, which represents the amount of water involved in one adsorption-desorption cycle. the experiment has consisted of loading adsorbent with water under a temperature desorbed at the temperature of 90 o c in the same of 35 o c, then the adsorbent were, afterwards, duration as the adsorption time. the difference between adsorbent loading at the end of the adsorption, and its loading at the end of desorption constitutes the water exchanged amount ( ). therefore, during the desorption phase, the refrigerant vapor was allowed to be collected via the flask by opening valve 6 (fig. 1). the measurment of the adsorpion capacity of this type of silica-gel showed that it is able to exchange a large amount of water of 0.08 kg/kg under operating conditions so it is typical for air conditioning applictions as well as to be driven by hot water temperaure of 90 o c. fig. 4. mass and concentration of water desorbed variation with time. 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0 10 20 30 40 m as s o f w at er a d so rb ed ( k g) time [min] 0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0 10 20 30 40 ∆ x ( kg /k g) time [min] mohammed a. atiya al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 6878 (2014) 73 4.3. cooling power, scp, and cop generally, cooling capacity, cp (or specific cooling capacity, scp) and cop are two parameters to determine the performance of the refrigeration cycle. the cycle time will be the best when the cp and cop reach their maximum values at the same time, but in real system, they are not [18]. the results for cooling capacity, cop, and scp values are shown in fig. 5. the cop has an optimum value of about 0.16 at the proposed first half cycle of 20 mins. indeed, the cop is affected by the dynamic limitations of the adsorbent bed, parasitic losses and inert mass of the heat exchangers. the scp reaches the peak value of 198.2 w/kg of dry adsorbent when the cycle time is 9.1 mins and decreases for a higher cycle time with minimum value of 163 w/kg at a time of 20 mins. cycle time at 9.1 mins or shorter resulted in lower performance of heat transferred/extracted to/from the adsorbent bed. moreover, in our case, the cycle time at 9.1 mins was not sufficient to complete the hydration of silica gel during adsorption phase. the obtained results indicate that the cycle time of 20 mins gives a reasonable compromise between the scp and cop. the cycle time of 9.1 mins allows maximizing the scp, while the maximum cop is obtained when the cycle time is 31 mins. this information is of a high practical significance when optimized for high cop and scp. in general, there designing an adsorption chiller that must be is a maximum of the cooling power (qe) at a specific cycle time. larger cycle time leads to higher coefficient of performance cop, but less cooling power. the relation is shown in fig. 5, it can be noted that by increasing the cooling time, the cooling power (qe) value increases and there is a maximum qe value (793 w) when the cooling time is 9.1 mins, after that the qe decreases as the cooling time increases. this time of 9.1 mins, is enough just to cool the adsorbent up to 42.5 o c, not to 35 o c, and the adsorbers are insufficiently cooled or heated during the adsorption and desorption processes respectively. however, the value of qe at 20 mins is 664 w, which is less than the maximum value by 149 w. but, it is still an acceptable value to work on. consequently, a strategy was adopted to assess the adsorption time of 20 mins. the same results are obtained for the cop and scp: increasing the temperature of the bed leads to increase the cooling power. fig. 5. experimental results of cop, scp, and cooling capacity as a function of the time. 4.4. effect of operating conditions on the system performance the tests for measuring the performance of the adsorber were continued by carrying out a large number of experiments under various operating temperatures. fig. 6 shows the cop and scp as a function of the bed temperature for the time of 20 mins. as expected, the variation of the bed temperature had strong effect on the performance. it can be observed that the performance increases when the bed temperature increases. however, adequate performance can be achieved even for a lower bed temperature. in particular, the cop of 0.072 and scp of 71 w/kg were measured for a bed temperature of 70 o c, demonstrating that this adsorbent can be driven by a low-temperature heat source. in general, there is a maximum of the cooling power (qe) at a specific cycle time. larger mohammed a. atiya al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 6878 (2014) 74 cycle time leads to higher coefficient of performance cop, but less cooling power. the relation is shown in fig. 7, it can be noted that by increasing the cooling time, the cooling power (qe) value increases and there is a maximum qe value (793 w) when the cooling time is 9.1 mins, after that the qe decreases as the cooling time increases. this time of 9.1 mins, is enough just to cool the adsorbent up to 42.5 o c, not to 35 o c, and the adsorbers are insufficiently cooled or heated during the adsorption and desorption processes respectively. however, the value of qe at 20 mins is 664 w, which is less than the maximum value by 149 w. but, it is still an acceptable value to work on. consequently, a strategy was adopted to assess the adsorption time of 20 mins. the same results are obtained for the cop and scp: increasing the temperature of the bed leads to increase the cooling power. fig. 6. experimental results of cop and scp as a function of the bed temperature. fig. 7. cooling capacity variations with bed temperature. 4.5. comparison with other adsorption chillers as discussed from the results, the chiller performance is quite similar to that on the former adsorption chiller [19-21]. compared with adsorber presented by chang et al. [19], this adsorber shows a lower refrigerant exchange amount ( kg h2o / kg adsorbent). according to chang et al., kg h2o / kg adsorbent, that the rectangular fins were used to extend the mass transfer area, while in this study, circular fin tubes were adopted in the adsorber. geyer and paar [20] built up a laboratory unit (approx. 1000 w cooling mohammed a. atiya al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 6878 (2014) 75 capacity) using a flat fintube heat exchanger. the maximum values of the cooling capacity and cop under operating conditions of hot water (= 80 o c), cooling water (= 27 o c), and entire cyle time (= 45 mins), were 700 w and 0.3, respectively [20]. it was close to the operating conditions of our results, but the difference is with the value of cop, which is higher in geyer and paar silica gel used in the experiment. another work. may be the reason is due to the properties of considered comparison is with the work of kubota et al. [21], who used 5.8 kg of dry silica gel in a circular finned-tube heat exchanger. however, his results showed that water exchange amount, kg h2o / kg adsorbent, for 6 min, hot water of 80 o c, and cooling water of 30 o c. while the cooling capacity and cop are 1200 w and 0.25, respectively. 4. conclusions in this paper, a new design of a fin-tube heat exchanger was presented and tested in adsorption chiller prototype. the measurement of the equilibrium properties showed that the silica gel adsorbent is able to exchange amount of 0.08 kg h2o/kg silica gel under the operating conditions of air-conditioning applications. considering, the results of this work for 20 mins adsorption time demonstrated that the values of cooling power, scp, and cop are 664 w, 163 w/kg adsorbent, and 0.16, respectively [21]. acknowledgment the authors would like to greatly acknowledge the r & d dep. (research & development department/ iraqi ministry of higher education and scientific research) for supporting this research through a program research missions. as well as extend our sincere thanks to lse (laboratory of solar energy) at fedral university of paraiba/brazil, where the prototype and experiments were carried out. nomenclature specific surface area, [m 2 /g] coefficient of performance specific heat of hot water, [kj/kg. o c] average particle diameter, [mm] latent heat of evaporation, [kj/kg] k thermal conductivity, [w/m. o c] mass of adsorbent, [kg] mass flow rate of hot water, [kg/s] cooling power, [w] specific cooling power, [w/kg] adsorption time, [min] desorption time, [min] isostering time, [min] cycle time, [min] cooling water temperature, [ o c] hot water in, [ o c] hot water out, [ o c] adsorption temperature, [ o c] desorption temperature, [ o c] concentration at specific time,[kg/kg] concentration at specific time,[kg/kg] ρ apparent density, [kg/m 3 ] mohammed a. atiya al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 6878 (2014) 76 5. references [1] hassan hz and mohamad aa, (2012). a review on solar-powered closed physisorption cooling systems. renewable and sustainable energy reviews, (16) 25162538. [2] chang kc, chen mt, and chung tw, (2005). effect of the thickness and particle size of silica gel on the heat and mass transfer performance of a silica gel-coated bed for airconditioning adsorption system.applied thermal engineering, (25) 2330-2340. [3] chen cj, wang rz, xia zz, kiplagat jk and lu zs, (2010). study on a compact silicagelwater adsorption chiller without vacuum valves: design and experimental study. applied energy, 87:2673-2681. [4] wang rz, ge ts, chen cj, ma q, xiong zq, (2009). solar soription cooling systems for residental applications: options and guidelines. int. j. refrig, 32:638-60. [5] khan mz, alam kc, bb saha, hamamoto y, akaisawa, and kashiwagi, (2006). parametric study of a two-stage adsorption chiller using re-heat-the effect of overall thermal conductance and adsorbent mass on system performance. international journal of thermal sciences, (45) 511-519. [6] wang dc, wu jy, xia zz, zhai h, wang rz, and dou wd, (2005). study of a novel silica gel–water adsorption chiller. part ii. experimental study international journal of refrigeration (28) 1084–1091. [7] demir h, mobedi m, and ulku s, (2009). effect of porosity on heat and mass transfer in a granular adsorbent bed. international communications in heat and mass transfer, (36) 372–377. [8] sapienzaa al, glaznevb is, santamariaa sa, frenia an, and aristov yi, (2012). adsorption chilling driven by low temperature heat: new adsorbent and cycle optimization. applied thermal engineering, (32) 141-146. [9] aristov yi, sapienza a, ovoshchnikov ds, freni a, and restuccia g, (2012). reallocation of adsorption and desorption times for optimisation of cooling cycles. internal journal of refrigeration (35) 525-531. [10] liu yl, wang rz and xia zz, (2005). experimental performance of a silica gel– water adsorption chiller. applied thermal engineering, (25) 359–375. [11] wang rz, xia zz, wang lw, lu zs, li sl, li tx, wu jy and he s, (2011). heat transfer design in adsorption refrigeration systems for efficient use of low-grade thermal energy. energy 36 5425-5439. [12] lu zs, wang rz, xia zz, wu qb, sun ym, and chen zy (2011). analysis of the performance of a novel solar silica gelwater adsorption air-conditioning. applied thermal engineering, 31(17-19): 3636-42. [13] wang d, zahng j, yang q, li n, and sumathy k (2014). study of adsorption characteristics in silicagel-water adsorption refrigeration. applied energy, 113; (734741). [14] freni a, sapeniza a, glavnzev i, and aristov y, (2012). experimental testing of a lab-scale adsorption chiller using a novel selective water sorbent “silica modified by calcium nitrate” international journal of refrigeration, (35) 518-524. [15] miyazaki t, akisawa a, (2009). the influenced of heat exchanger parameters on the optimum cycle time of adsorptions chilles. applied thermal engineering, (29) 2708-2717. [16] naizamandh and dabazdehi(2012). numerical simulation of heat and mass transfer in adsorbent beds with annular fins. international journal of refrigeration, (35) 581-593. [17] wen w and ruzhu w (2005), investigation of non-equilibrium adsorption character in solid adsorption refrigeration cycle. heat mass transfer, 41: 680-684. [18] graber m, kirches b, bock h, johannes p. schloder b, tegethoff w, and kohler j, (2011). determining the optimum cyclic operation of adsorption chillers by a direct method for periodic optimal control. international journal of refrigeration, (34) 902-913. [19] chang kc, chen mt, and chung tw, (2005). effect of the thickness and particle size of silica gel on the heat and mass transfer performance of a silica gel-coated bed for air-conditioning adsorption system. applied thermal engineering, (25) 23302340. [20] geyer j and paar k, (2005). development of a low capacity adsorption chiller. europastraße 1 a-7540 güssing, austria. [21] lattief, f. a., (2014), "design and performance of a solar powered adsorption air-conditioning system” ph.d. thesis, baghdad university. (2014) 6878، صفحة 3، العدد10دجلة الخوارزمي الهندسية المجلالسراج ممحمد عبد عطية 77 الغراض تبريد الهواءلمبرد امتزازي ذو انبوب زعنفي للسيلكا جل التجريبي األداء *محمد عبد عطية السراج ***عادل احمد عوض * *فرقد علي لطيف جامعة بغداد/ عميد كلية الهندسة الخوارزمي* وزارة التعليم العالي والبحث العلمي/ دائرة البحث والتطوير** بغدادجامعة / كلية الهندسة / قسم هندسة البيئة **** mohatiya1965@gmail.com : االلكتروني البريد* farkad400@yahoo.com **االلكتروني البريد : hemiri2004@gmail.com: االلكتروني البريد*** الخالصة ،ين كفاءة انتقال الحرارة والمادةفمن اجل تحس. ة االمتزازوحد موديل تغيير في بالمرونة يتسم لمنظومة تبريد الهواء اختبار جهاز بناء البحث هذا يعرض ،6136 و كجم/ واط 361 هي (cop) األداء ومعامل (scp) التبريد سعة أن النتائج أظهرت. مزود بزعانف لوحدة االمتزاز حراري مبادل استخدام تم ودرجةمئوية درجة 16 التبريد مياه ودرجة حرارةمئوية، درجة 06 الساخن الماء حرارة ودرجة دقيقة، 06 هو دورةال وقت يكون عندما التوالي، على .درجة مئوية 3310 المبرد الماء حرارة mailto:mohatiya1965@gmail.com*البريد mailto:mohatiya1965@gmail.com*البريد mailto:antpralon@yahoo.com**البريد mailto:antpralon@yahoo.com**البريد mailto:farkad400@yahoo.com****البريد (microsoft word \335\321\307\323 \346\307\323\343\307\301124-136) al-khwarizmi engineering journal al-khwarizmi engineering journal,vol. 13, no. 4, p.p. 124136 (2017) applying a* path planning algorithm based on modified c-space analysis firas a. raheem* asmaa a. hussain** *,* *department of control and systems engineering/ university of technology *email: 60124@uotechnology.edu.iq **email: asmaa.alshawi@yahoo.com (received 25 october 2016; accepted 7 march 2017) https://doi.org/10.22153/kej.2017.03.007 abstract in this paper, a modified derivation has been introduced to analyze the construction of c-space. the profit from using c-space is to make the process of path planning more safety and easer. after getting the c-space construction and map for two-link planar robot arm, which include all the possible situations of collision between robot parts and obstacle(s), the a* algorithm, which is usually used to find a heuristic path on cartesian w-space, has been used to find a heuristic path on c-space map. several modifications are needed to apply the methodology for a manipulator with degrees of freedom more than two. the results of c-space map, which are derived by the modified analysis, prove the accuracy of the overall c-space mapping and construction, and then a successful and guaranteed path from a start to goal configuration has been obtained without any collision probability. the results had been achieved by (matlab r2015a) software, which run on intel (r) core (tm) i3-3120m cpu. keywords: configuration space, degrees of freedom, topology, path planning. 1. introduction due to the importance of path planning and obstacle avoidance problems in practical areas, there are more researches and studies about it in the last decades. in the classical mechanics, the configuration space (c-space) represent very important tool to describe and analyze the motion planning for many important systems, especially in robotics [1]. to understand the c-space, first it is important to know what the term of configuration means in robotic systems. it means a complete description, which determines every point position on the robot uniquely. so, the c-space of a robot typifies the space of all configurations, which are processed by the robot. as the robot has n degrees of freedom, the c-space for this robot is ndimensional [2]. c-space deals with static obstacles, or dynamic obstacles with slow motion. also, the shape and dimensions of each obstacle must be known before finding c-space construction if the path planning that will be used is off-line. from the first time the c-space was defined [3], it played very important role in robotic systems especially in path finding problem. then, the usage of c-space continue in many researches and applications. until today, more analysis and modifications with many type of robots are applied on c-space [47]. path planning for robot arm requires optimized global path generation, in which the robot arm can avoid any obstacle in the cartesian w-space. the feasibility of path planning depends on some factors: map accuracy, number of obstacles and current configuration of the robot. there are many approaches and algorithms have been proposed to solve the path planning problem. this problem is related with finding the shortest path between the start and goal configurations. the most known firas a. raheem al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 124136 (2017) 125 algorithms that are being used to find shortest path are graph search algorithms. these algorithms are based on node-edge marking [8]. graph search methods speculate the cost and generate a sequence of segments that extent from the start point to the goal point through vertices [9]. one of the graphical search methods is the a* algorithm. it is a graph, heuristic and greedy search algorithm, that means the determined solution is approximated not optimal (it is best-first search) [10]. the main advantage of a* that it can be modified easily and by change the weights of the traversal costs, it can be extended [11]. usually a* algorithm is applied to find the path on cartesian w-space, while in this paper, a different approach adopted by the application of a* algorithm on c-space analysis, which includes a modified derivation based on geometrical analysis to find the construction of cspace for two revolute joints planar robot arm. 2. modified c-space derivation for a manipulator, the space that represented by the variable parameters of joints, either slide position or rotation angles, is called c-space. it includes two main regions: c-free and c-obstacle, in which the second region is a prohibitive because it represents collision between the robot arm and obstacles and between the links of the robot arm [4]. the geometrical representation of the obstacle (s) can be denoted as �, so the configuration space obstacles will be as below [1]: ���� = { : �� ∩ � ≠ ∅} … �1 while c-free can be represented as below [1]: ����� = { : �� ∩ � = ∅} … �2 where: ���� : c-space obstacles : robot configuration �� : the set of points of the space confined by the robot at configuration the c-space as overall can be defined as [1]: ������ = ���� ∪ ����� … �3 the mathematical study of the surface properties, which are do not change if this surface has been applied for certain deformations, such as bending or stretching, is called topology of space. the topology for robot arm with two revolute joints can be described as [12]: �� ∗ �� = ! … �4 the above equation means that the c-space for two revolute joints robot arm is a torus (with no joint limits for the joints). where �� is the circle description, and !is the 2-dimensional torus surface [12]. each joint angles pair is corresponded by a unique point on the torus. (a) 2r robot arm (b)2torus (c)sample representation fig. 1. topologically representation of the 2dimensional c-space [12]. to find the mapping of c-space, there are some basic shapes of the obstacle(s) will be analyzed. 2.1. c-space construction for point obstacle mathematically, the simplest obstacle may be found in the workspace is the point. in this paper, a modified derivation for c-space analysis will be discussed, in which the collision checking based on geometrical analysis. 1) first link-point obstacle a collision between the first link and the point obstacle will acquire if the following condition achieve: #��� = #� $%& '� ≥ ) $%& *� ≥ % … �5 where: d��� = -./ 0./ ; #��� =tan.� 0 ; … �6 '�, *�: first link end effector coordinate ), %: point obstacle coordinate firas a. raheem al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 124136 (2017) 126 2ᶿ point obstacle first link reachability circle 1ᶿ obsᶿ fig. 2. the first link with the point obstacle geometrical analysis. for fig. 2, the coordinate of point obstacle is inside the first link reachability circle. if the slope of the first link equal to the slope of the point obstacle, the collision is acquire. 2. second link-point obstacle the following mathematical derivation explains the condition of collision between the second link and point obstacle: 7 = 8 − #! … �7 ; = #��� − #� … �8 by sine's law: => ?@a b = cdef ?@a g h = sin.� =>∗?@a g cdef … �9 while, l7 + ; + hn = 8 … �10 there is a collision between the robot and the point obstacle, where (7, ; and h) are the angles used for the analysis as shown in fig. 3. point obstacle fig. 3. the second link with the point obstacle geometrical analysis. these collision conditions are applied for any position of the point obstacle inside first or second link, not only at the end effector for each of them. 2.2. c-space construction for line obstacle the robot links can be handled as two lines, with regardless of their width. in our research, the modified derivation of c-space analysis includes two analyses for checking collision. analysis one to implement the checking, there are several constraints can be put: 1) first link – line collision in fig. 4, if the first joint angle, at specific configurations, has values locate at the range of angles of end points for line obstacle, this may cause collision between the first link and the obstacle: #p� ≤ #� ≤ #p! … �11 where: #pr : the angles of line obstacle end points, i = 1, 2. it is important to take in consideration that the length of the first link equal or more than the distance between the robot's base and the line obstacle, as in the following equation: s'�, *�t ≥ u'=v , *=vw … �12 s'�, *�t : the coordinate of first link end effector s'=v , *=vt : matrix of line obstacle points j=1, 2, …, number of line obstacle points (a) horizontal line (b) vertical line (c) sloping line fig. 4. cases of first link – line obstacle collision. 1) second link – line collision as it was done in checking collision with point obstacle, the geometrical analysis can be used to find the collision angle between the second link and the line obstacle. equations (5, 6, 7, 8, and 9) can be used but it is applied for the intersection point between the second link and the line obstacle. firas a. raheem al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 124136 (2017) 127 fig. 5 illustrate the situations of collision between the second link and the line obstacle. obsᶿ obsᶿ obsᶿ obsd obsd (a) horizontal line (b) vertical line (c) sloping line fig. 5. cases of second link – line obstacle collision. analysis two another method for checking collision by checking the equality of each link slop with the slop of each point in the line obstacle: for the first link: x>./ y>./ = xz[./ yz[./ … �13 for the second link: x\.x> y\.y> = xz[.x> yz[.y> … �14 an important condition must be considered for equations (13) and (14): the length of each link should be more than or equal to the distance of the robot's base to that point (for equation 13) or from the first link end effector to the point (for equation 14). 2.3. c-space construction for polygonal shapes obstacle any two dimensions shape formed by straight lines, is called polygon. it has three lines (such as triangle), four lines (such as square, rectangle, rhombic… etc.), or more [13]. so the same methods that have been used for line obstacle can be used here. 2.4. c-space construction for circle obstacle for a circle that is known in center ('� , *�) and radius (rad), the collision can be checked by the following modified derivation of c-space analysis: the distance from the center of the circle to each point on the first and second link will be calculated: for the first link: &��] = ^�'� − ] ∗ '� ! + �*� − ] ∗ *� ! … (15) for the second link: &!�] = ^�'� − _! ! + �*� − !̀ ! … �16 _! = '� + ] ∗ a! ∗ cos�#� + #! … �17 !̀ = *� + ] ∗ a! ∗ sin�#� + #! … �18 d� = mins&��] t … �19 d! = mins&!�] t … �20 where: ] = 0.1, 0.2, … , � it is important to denote that ] is the resolution step of deviation of each link, while � is the total length of link. theoretically, the step ] may be taken 0.1, smaller than 0.1, or biggest. if the following condition verified, that means there is a collision between the circle obstacle and the robot arm: dr ≤ g$& … �21 h = 1, 2. the distances &r can be implemented by the form of deviation as below: &r� = s&r�, &r!, … , &rit … �22 j: number of steps of deviation (]). fig .6 show the distances that used in the analysis for checking collision with circle obstacle. )cy,cx( fig. 6. geometrical analysis of circle obstacle. 3. a* algorithm a* algorithm is most familiar search algorithm that is used to find the shortest path. it represent an extension of dijkstra's algorithm. the usage of heuristic is what make the a* different from another graph search algorithms. the heuristic provides an estimated distance from a current node to the goal node, it denoted by h(n), also the a* take in account the cost from the start node to the current node, and it is denoted as g(n). the cost function is determined as below [9]: f(n) = g(n) + h(n) … �23 firas a. raheem al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 124136 (2017) 128 for c-space map, each node represented by a pair of joint angles, n: (#�, #!). the a* algorithm includes two lists: open list (o_list) and closed list (c_list). it choose the nodes that have minimum cost functions to create a path from start node to goal node. the fulfillment of this algorithm on c-space map can be explained briefly by the following flowchart: c-space construction discretizing c-space map initialization of start configuration end remove n_best at which f(n_best)<=f(n) from o-list to c_list end expand all n_best neighbor nodes that not in c_list add current node to o_list if g(n_best)+path cost<g(current node):update back pointer(current node)=n_best yes no yes no yes no start is o_list empty? n_best=goal configuration? current node is in o_list? fig. 7. a* algorithm on c-space map flowchart. 4. results and discussion the results of finding c-space construction and applying a* algorithm on it, will be displayed and discussed in section 4.1 and 4.2 respectively. 4.1. c-space construction results for the point obstacle, it can be observed that the c-space map of the collision between the first link and the point obstacle has the straight-line shape, fig. 9, while the collision between the second link and the point obstacle has a curved shape. the upper curvature is the result of elbow down configuration, fig. 8, and elbow up configuration form the lower curvature as in fig. 10. (a) ra d , 2 ө rad, 1ө (b) fig. 8. (a) second link-point collision in elbow down in cartesian w-space. (b) corresponding c-space map. firas a. raheem al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 124136 (2017) 129 (a) ra d , 2 ө rad, 1ө (b) fig. 9. (a) first link-point collision. (b) corresponding c-space map. (a) ra d , 2 ө rad, 1ө (b) fig. 10. (a) second link-point collision in elbow up. (b) corresponding c-space map. as the point obstacle approaching to the end effector of the robot arm, the c-space obstacle points will decrease, as shown in fig. 11. (a) ra d , 2 ө rad, 1ө (b) fig. 11. (a) point obstacle collides with second link only. (b) curve points decrease as the point be nearest to the end effector. firas a. raheem al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 124136 (2017) 130 the c-space map of line obstacle and polygonal shape obstacle is achieved by the analysis introduced previously in section 2.2 and 2.3. the same shape of the curve of c-space map for point obstacle applied for each point on the line(s). here, these curves in compact form will represent the cspace line or polygonal obstacles, as illustrated in fig. 12 through fig.15. (a) ra d , 2 ө rad, 1ө (b) fig. 12. (a) robot arm with line obstacle in workspace. (b) corresponding c-space map. (a) ra d , 2 ө rad, 1ө (b) fig. 13. (a) robot arm with square obstacle in cartesian w-space. (b) corresponding c-space map. (a) (b) fig. 14. (a) robot arm with rectangular obstacle in cartesian w-space. (b) corresponding c-space map. firas a. raheem al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 124136 (2017) 131 (a) ra d , 2 ө rad, 1ө (b) fig. 15. (a) robot arm with octagonal obstacle in cartesian w-space. (b) corresponding c-space map. the figures (12-15), represent the case of collision with both links. the number of points on c-space map are increase as the obstacle in the cartesian w-space be near to the first link. in addition, it can be observed that the ����� is on the both sides of the ���� . therefore, to find the path from one side to other, the range of changing #� is chosen in somehow for unification the region of �����which make the path planning easier. for circle obstacle, fig. 16, there are two main parts of edges of the c-space map. first, the collision between the first link and the circle obstacle circumference, which represented by the vertical straight lines with all values of #!. second, the outer upper and lower curved shapes represents the collision between the second link and the circle obstacle circumference. (a) r a d , 2 ө rad, 1ө (b) fig. 16. (a) robot arm with circular obstacle in cartesian w-space. (b) corresponding c-space map. for any c-space obstacle shape, the map of cspace is formed by matched angles. each pair of matched points in the obstacle in cartesian wspace has a pair of matched angles in c-space. for example: table 1, two matched points in cartesian w-space and their symmetry angles in c-space x(m) y(m) kl�mno. kp(deg.) 0.5808 0.2111 -52 144 0.211 0.5808 142 -144 this pair of points represent the first point and last point on the c-space map for circle obstacle with center of (0.5, 0.5) and radius equal to 0.3 m, which is illustrated in fig. 17. it can be seen that the symmetry points on c-space have the same #! value with different sign, which is verifies the two solutions of elbow up and elbow down of the second joint. firas a. raheem al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 124136 (2017) 132 fig. 17. the matched points analyzing for circle obstacle. for any obstacle shape, if there is a collision between the robot links and the circumference of that obstacle, by the way any inner point of the obstacle has a corresponding point on the c-space map. 4.2. results of applying a* algorithm on modified c-space the following two environments have different obstacle shapes and tasks. first, we do all the steps of c-space analysis and then the construction to get the exact map, which includes the collision and free areas. second, the start and goal configuration, which are represented by the dot and the star shape respectively, have been computed by the inverse kinematic equations. for the first and second environment, the start and goal points represented by the dot and the star shape respectively. fig. 18. cartesian w-space of the first environment. fig. 19. c-space map of the first environment. d e g , 2 ө deg, 1ө start point goal point fig. 20. a* path in c-space map for the first environment. start point goal point fig. 21. the movement of robot arm from start to goal point for the first environment. firas a. raheem al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 124136 (2017) 133 fig. 22. two-link robot arm end effector path in cartesian w-space for the first environment. start point goal point fig. 23. cartesian w-space of the second environment. ra d , 2 ө rad, 1ө start point goal point fig. 24. c-space map of the second environment. d e g , 2 ө deg, 1ө start point goal point fig. 25. a* path in c-space map for the second environment. start point goal point fig. 26. the movement of robot arm from start to goal point for the second environment. start point goal point region (b) region (c) fig. 27. two-link robot arm end effector path in cartesian w-space for the second environment. firas a. raheem al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 124136 (2017) 134 from fig.18 and fig.23, both environments considered as a crowded environments because all obstacles are closed to the arm links with different distances. after getting the c-space construction of these environments, fig.19 and fig.24 show the overall c-space map, which include the ����� , ���� and the start and goal configuration. according to the a* path on c-space map, as observed in fig.20 and fig.25, the movement of the robot arm prove the success of a* algorithm on these maps, because in spite of the nearness of obstacles from the robot links, it can rescue itself from the crowded region and complete a smoothed path, as in fig.21 and fig.26. in addition, it is clear that if the a* path on c-space is optimal; it is not a condition to be optimal on cartesian w-space for the same environment, and vice versa, but it represent a best solution for planning the path of the two revolute joints planar robot arm between obstacles. in the end effector path for both environments, fig.22 and fig.27, it is transparent there are several curved regions, denoted by region (a) in fig.22 and regions (b) and (c) in fig.27, represent a reflection of robot arm carful movement at these regions to avoid collision with obstacles. this sudden change insure the complete avoidance of the robot arm from obstacles. the resulted path and the changing of joint angles in c-space has the behavior shown in fig. 28 and fig. 29 respectively: iterationsiterations d e g , p a th _ 1 ө d e g , p a th _ 2 ө fig. 28. the path of first and second joint angles along the iterations for the first environment. the change of joint angles can be calculated from the following equation: ∆#r = #r�r − #r�r − 1 … �24 where: ∆#r= change of joint angles, i= 1, 2. t: current iteration. iterationsiterations p a th _ 2 ө ∆ p a th _ 1 ө ∆ fig. 29. changing of first and second joint angles along iterations for the first environment. d e g , p a th _ 1 ө d e g , p a th _ 2 ө fig. 30. the path of first and second joint angles along the iterations for the second environment. p a th _ 2 ө ∆ p a th _ 1 ө ∆ fig. 31. changing of first and second joint angles along iterations for the second environment. from the above results, fig. 30 and fig. 31, the path and the behavior of changing each joint angle for the first environment is smooth. while the results of the second environment show there is a little of zigzag in the behavior of first joint angle because of the nearness of the triangular obstacle from the end effector path, so that was reflected on c-space by making the path take the form of the same obstacle border at particular region. firas a. raheem al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 124136 (2017) 135 5. conclusion and discussion the methodology of this work can be applied for any type of robot manipulator. here, we tested it on 2r planar robot arm. in c-space, in general, the robot arm at specific configuration can be represented as a point in c-space map, which represent the values of first and second joint angles at this configuration. the step of changing joint angles had been chosen with particular value in order to achieve sufficient discretization resolution for getting accurate c-space map. the modification on c-space has been done by checking all the odds of collision by modified derivation depending on geometrical analysis. this analysis ease in application and gave accurate and exact c-space map. after applying a* algorithm on modified cspace, we achieve a shortest, safe, and rather smooth path. (matlab r2015a) was used to program the c-space construction and the algorithm of a*, that was by intel (r) core (tm) i3-3120m cpu. the key advantage of applying a* on c-space map not on cartesian w-space is insuring the path in the safe area. for future work, the a* algorithm results can be enhanced by using classical interpolation equations. 6. references [1] jia pan, dinesh mancha, "efficient configuration space construction and optimization for motion planning", published by engineering sciences press, 2015. [2] benjamin wah, "robot motion planning", wiley encyclopedia of computer science and engineering, 2008. [3] t. lozanopérez, "spatial planning: a configuration space approach", ieee computer society washington, dc, usa, 1983. [4] kasper althoefer, "neuro-fuzzy motion planning for robotic manipulators", department of electronic and electrical engineering, king's college london, university of london, 1996. [5] wyatt s. newman, michael s. branicky, "realtime configuration space transforms for obstacle avoidance", the international journal of robotics, 1991. [6] debanik roy, " serial and parallel robot manipulators – kinematics, dynamics, control and optimization ", edited by serdar küçük, janeza trdine 9, 51000 rijeka, croatia, 2012. [7] [yan yan, "geometric motion planning methods for robotics and biological crystallography", baltimore, maryland, 2014. [8] s. m. masudur rahman al-arif, a. h. m. iftekharul ferdous, sohrab hassan nijami, " comparative study of different path planning algorithms: a water based rescue system ", international journal of computer applications (0975 – 8887) volume 39– no.5, february 2012. [9] sung hyun kim, "multi-layer approach to motion planning in obstacle rich environment", texas a&m university, may 2008. [10] suraya binti abu bakar, "high-speed shortest path co-processor design", university of malaya, kuala lumpur, october 2010. [11] steven bell student member, "an overview of optimal graph search algorithms for robot path planning in dynamic or uncertain environments", ieee student member no. 90691022, oklahoma christian university, 19 march 2010. [12] f. c. park, k. m. lynch, "introduction to robotics: mechanics, planning, and control", 2015. [13] ethan d. bloch, "polygons, polyhedra, patterns & beyond", 2015. )2017( 124-136، صفحة 4د، العد13دجلة الخوارزمي الهندسية المجلم فراس عبد الرزاق رحيم 136 المعدل c-spaceلتخطيط المسار على تحليل *aتطبيق خوارزمية فراس عبد الرزاق رحيم* أسماء عبد اللطيف حسين** الجامعة التكنولوجية /**قسم هندسة السيطرة والنظم،* uotechnology.edu.iq@60124*البريد االلكتروني: asmaa.alshawi@yahoo.com**البريد االلكتروني: الخالصة وسهولة. ) هي لجعل عملية تخطيط المسار أكثر امانc-space. الفائدة من استخدام ()c-spaceفي هذا البحث، تم تقديم اشتقاق مستحدث لتحليل بنية ( ) لذراع الروبوت ثنائي الذراع، والتي تتضمن كل احتماالت االصطدام بين أجزاء الروبوت والعوائق المحيطة به، c-space( بعد الحصول على بنية وخارطة -cمسار المخمن على خارطة (، والتي عادة يتم تطبيقها في مجال العمل الكارتيزي للروبوت إليجاد المسار المخمن، تم تطبيقها إليجاد ال*aخوارزمية spaceحريات حركة أكثر من اثنين. نتائج خارطة ( يريقتنا المطورة على ذراع روبوت ذ). بضع تعديالت الزمة لتطبيق طc-space والتي تم اشتقاقها ،( ية الى نقطة الهدف تم الحصول عليه بدون أي ) وبنيته، ومن ثم مسار ناجح ومضمون من نقطة البداc-spaceبطريقتنا المطورة، تثبت دقة الخارطة الكلية ( intel (r) core (tm) i3-3120m باستخدام حاسبة بالمواصفات التالية: (matlab r2015a)طة برنامجاستم الحصول على النتائج بو احتمالية اصطدام. cpu. microcontroller-based function generator al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 5, no. 1, pp 83-93 (2009) multidimensional systolic arrays of lms algorithm adaptive (fir) digital filters riyadh a.h. al-helali * and bakir a. r. al-hashemy** * department of electrical engineering / al-mustansiriyah university ** department of electrical engineering / baghdad university (received 12 june 2006; accepted 6 april 2009) abstract a multidimensional systolic arrays realization of lms algorithm by a method of mapping regular algorithm onto processor array, are designed. they are based on appropriately selected 1-d systolic array filter that depends on the inner product sum systolic implementation. various arrays may be derived that exhibit a regular arrangement of the cells (processors) and local interconnection pattern, which are important for vlsi implementation. it reduces latency time and increases the throughput rate in comparison to classical 1-d systolic arrays. the 3-d multilayered array consists of 2-d layers, which are connected with each other only by edges. such arrays for lms-based adaptive (fir) filter may be opposed the fundamental requirements of fast convergence rate in most adaptive filter applications. keywords: adaptive signal processing; lms algorithm; vlsi signal processing. 1. introduction high-speed multidimensional digital filtering is very useful for real-time video signal processing such as video image coding, bandwidth compression, sampling rate conversion and the enhancement of televisions signals [1]. as a first step toward the implementation of an algorithm onto a processor array, it is common practice to go through a number of refinements (regularization, single assignment form….) that make the algorithm more suitable to a simple and modular vlsi design. the usual assumption is that the algorithm can be expressed by a system of recurrence equation [2]. many emerging applications of specific systems characterized by many features which are the problem size begins to grow so as to guarantee better quantity of solutions and the problems must be implemented in real-time. these features demand high-performance computers. the algorithms, used by these applications, are typically highly parallel consisting of a huge number of simple and regular computations. these applications emphasis different demands on the processor design than the classical numerical and necessitate finding the new architectural solutions for processors [3]. systolic arrays have been one of the more interesting paradigms for reconfigurable computing in recent times because the design process creates an excellent paradigm for implementing algorithms via space and time transformations [4]. real-time systolic implementations of multidimensional recursive digital filters have been discussed in prior work [5]-[8]. however, prior work has concentrated either on minimizing the critical path (that is, the unlatched signal path that requires the longest processing time) [5], [6] or on achieving the modularity or regularity of filter structures [7]-[8]. thus the previously proposed filter structures do not satisfy the practical requirement of simultaneously having a critical path containing no more than one multiplier and one adder and the desired modularity and regularity. moreover, they do not provide the property of local interconnectivity, which is essential in deep submicron vlsi implementations. in [1], proposed 1-d ladder filter structure based on which introduced a multilevel approach to derive multidimensional riyadh a.h. al-helali al-khwarizmi engineering journal, vol. 5, no. 1, pp 83-93 (2009) 84 ladder filter structures that are regular, modular and locally interconnected on the one hand, and yet have the shortest critical path of one multiplier plus one adder and the canonic number of storage registers in the higher dimensions (e.g., image line and frame registers). dedicated vlsi processors/chips are not always suitable for this purpose due to the need to provide flexible devices that can be adjusted to the new problems and problem sizes [9]. thus, the processors must be reprogrammable or reconfigurable. iso-plane method may be introduced [4]. in this case the problem is represented by iso-planes instead of a dependence graph in the classical case. iso-planes describe shared variables and reduction operators. to extract more parallelism from a problem specification, the idea of increasing the dimensionality of problem representations is introduced. this is based on tilling and expanding of the index space [2]. increasing the degree of parallelism demands an increase in the number of processor elements (pes) to be employed. this is possible only either by increasing the dimensionality or the dimension of the array. increasing the dimensionality of an array can result in a more efficient parallel algorithm implementation (parallel computing). this paper demonstrates how to extend existing designing methods for systolic arrays [11, 12, 13] and benefits from the approach in [4] to synthesize multilayered structures. this approach is demonstrated on the basis of 1-d convolution (inner product sum) of the output, which gives flexibility in the design procedure for extracting more than one array. systolic arrays for 1-d lms-based adaptive (fir) filter that decreases the latency has the area complexity o(n) while the latency time complexity is o(n 1/2 ). arrays with the increased throughput rate have the area complexity o(sn) , 1 ≤ s < n , and the time complexity is o(n/s), where n and n are sizes of two sequences of the inner product sum output. this decreasing latency time and increasing throughput rate limits the inherent limitations of lms algorithm, which necessitates a compromise between the opposing fundamental requirements of fast convergence rate and small maladjustment for high area complexity. in section 2, a mapping of regular algorithms onto multilayered 3-d reconfigurable processor array is described to design the systolic arrays, that it achieves the optimum local interconnection pattern and the highest speed. the complete 2-d and 3-d design of systolic lms-based adaptive (fir) digital filter is given in section 3. in section 4, we discuss the throughput and processing rate of the system. a comparison is made between the lms systolic array and the serial design employing fast convolution and fft as regards throughput. finally, we present conclusions in section 5. 2. mapping procedure regular array design means that the order of computations of reduction operators and the order of spreading shared variables must be chosen [4]. imposing a partial order onto iso-planes will do this. different partial orders can develop to improve the array design that affects on the structure and time parameters, such as latency and throughput rate. imposing a partial order onto an iso-set produces dependence vectors  y = x +  , x,y  iso v (x) . therefore, the affine equations are transformed into uniform recurrences. to offer a regular array design, the number of dependence vectors must be as small as possible. the corresponding regular array can be derived by an affine space-time mapping [2]. is` = t(is) +  …(1) where is  rz and is`  rz are the source and the target polytopes, respectively, t  rrz  is a transformation matrix and = rz is an offset vector. space-time mapping transforms the source polytope is into a target polytyope, is`, that contains the same points but in a new coordinate system in space and time: every x  is is mapped to the possible time step: t(x) = x +  …(2) and to the possible pe: a(x) = x + …(3) where   rz is a time schedule and   r)1r( z  is allocation,   z,   1rz  .  and  are components of the transformation [4]          t … (4) riyadh a.h. al-helali al-khwarizmi engineering journal, vol. 5, no. 1, pp 83-93 (2009) 85 to be a valid mapping, transformation t must satisfy certain constraints: 1. the time schedule  must be consistent with the dependence vector , i.e.   0. 2. the second constraint excludes the conflict that two distinct computations would be scheduled for the same processor at the same time, i.e. transformation t must be bijective. and thus  t   0. if the transformation is unimodular, i.e.  t   1, then the resulting array uses each time step efficiently, and, thus, this design is usually preferred. in this case, when  t   k, k  1, each processor works only in every kth time steps, thus less efficiency. the channels between processors can be computed from dependence vectors and transformation. each dependence vector  produces a channel l: l = t …(5) with the direction: ldir() =  …(6) and the delay: ldel() =   …(7) 3. systolic design of lms algorithm using iso-plane method the systematic design of this method gives various (1-d) and (2-d) arrays with modified property comparison to classical method as follows: 3.1 (1-d) classical systolic array of lms algorithm 1-d convolution sum of the inner product of the tap-weight vector and the tap-input vector, as represented as [10]; (a) (b) …u2u1u0 …  q m ŵ1  q m ŵ2  q m ŵ3  q m ŵ9 ….d2 d1 d0 . y2 y1y0 e _ +  q m ŵk uh uh ei “1” ei yi begin uh:= uh ; ei:= ei ; q := uh; m := qei; ŵk:= ŵk + m yi:= yi + ŵkuh end fig. 1. (a) 1-d systolic array realization for lms algorithm. (b) functional specification of a pe. riyadh a.h. al-helali al-khwarizmi engineering journal, vol. 5, no. 1, pp 83-93 (2009) 86 1)k-u(n m 1k * k w)n(y    …(8) = ŵ h (n)u (n) when the superscript h signifies hermitian transposition, and the inner product of the tapweight vector ŵ(n) and the tap-input vector u (n) represents the output of the filter, and is specified as: ( i: 0 ≤ i    …(9) yi = (∑ j : 1 ≤ j   : ŵ[ j ]u[i – j + 1])), where ŵ[j] and u[i] are weight and input sequences respectively, and yi is an output sequence. in practical applications m « n. two shared variables, ŵ[k] and u[i], are used by several operators (multiplications) for computing different instances of the variable yi by the reduction operator ∑. the index space is a 2-d polytope: is = {[i,j] t | 0 ≤ i ≤ n   ≤ j   … (10) each instance, i, of a variable, say vi, is represented by an iso-plane iso v (x), x  is [4]. the respective source polytope with iso-planes is depicted for kernel size m = 9 and n = 15. the 2-d index space for 1-d convolution sum of the inner product ŵ h (n)u (n) gives the channels applied to each point of allocation space, the respective allocation direction and the direction of channels for variables. therefore; the required 1d lms systolic array can be derived from the inner product algorithm as derived in [14] and represented as shown in figure (1). 3.1.1 decreasing the latency it is possible to speed-up the computations using recursive doubling that guarantees the logarithmic time complexity in the case of associative and commutative reduction operators. the same approach can be used and decompose the reduction operator into several parts that will be evaluated in parallel. this gives an increase in the degree of parallelism and decrease in the latency [4]. partitioning and expanding the index space can be used; such step increases the array dimensionality. partitioning of the range of index, i, is defined by a vector: pi = pj  ≤ j  r ……(11) where r is the dimensionality of the index space. if j = i, then pj > 0, otherwise, pj = 0. the vector pi defines the factorization of the upper bound, n, of index, i, by setting n = pi si for appropriate natural numbers pi and si. depending on the inner product ŵ h (n)u(n) of lms algorithm, the 2-d systolic array realization for lms algorithm can be derived. the large boxes in figure (2-a) represent the processor elements and its functional specification is in (b) of the same figure. 3.1.2 increasing the throughput rate classical systolic arrays implement lms algorithm sequentially, i.e., they input and output data sequentially. this put the limit onto throughput rate and time complexity – the linear a3 a9 a6 a2 a8 a5 a1 a7 a4 f i g u r e خ ط ! أ ال ي و ج د ن ص م ن ا ل من ط ا مل ع ي + di ui ui 0 “0” 0 0 yi u a u' e y u e procedure 2-d lms begin uh:= uh ; ei:= ei ; q := uh; m:= qei; ŵk:= ŵk + m yi:= yi + ŵkuh end fig. 2. (a) (2-d) systolic array realization of lms algorithm. (b) functional specification of a pe. riyadh a.h. al-helali al-khwarizmi engineering journal, vol. 5, no. 1, pp 83-93 (2009) 87 complexity is the best that can be achieved. to improve the time parameters of systolic arrays, several data items must be entered into the array simultaneously. this is achieved using partitioning of the range of input stream, forming thus a 2-d input stream instead of a 1-d stream in the classical case. the data items must be entered into the array in parallel, for each pi data inputs and thus needs a new block which converts the serial (m-tap) data sequence into the required pi parallel data that named serial to parallel converter [15]. the systolic array representation of the convolution sum, which was derived in [4] and increased the throughput rate, is used to derive the corresponding lms array in figure (3). 3.1.3 improving the latency and throughput to increase the throughput rate and decrease the latency, one can partition the ranges of indexes: the ranges of index i that describes the reduction operator and the range of index j, which described the input stream. the corresponding 4-d polytope shape has index point: x = [i, j, l, k] t and the allocation is taken along the axis k that provides regular structures as depicted in [14]. depending on the inner product ŵ h (n)u(n) of the required adaptive transversal filter with the assumed coefficients order, the whole array structure of the lms algorithm can be suggested by entering the error signal through the array and compute the updated values of the tap-weight vector, the filter output is shown in figure (4). in this improvement, also the data items must enter, simultaneously for each pi inputs, into the general array structure of the layers that prepare the incoming pi inputs data according to certain sequence to enter to its own (2-d) array layer and then get the outputs from the summation circuits assigned to each layer structure. thus, the whole systolic array represents a 3-d systolic array of the size 333 for a 1-d computational operations as shown in figure (4). 4. throughput and processing rate now by using the systolic arrays and applying the simulation of data flow, we find that: 4.1 classical systolic arrays the designed systolic arrays of the inner product ŵ h (n)u (n) and the lms algorithm by iso-plane method have the same performance of quantities of that designed by dependence graph method, but gives flexibility of increasing in the degree of parallelism and improving the algorithmic properties by partitioning and expanding the index space as in the previous section. 4.2 systolic array to decrease the latency by taking the 2-d semi-systolic array realization for the lms algorithm that designed in chapter three in figure (2). consider the data flow for several consecutive clock periods, applying the procedure to be executed by each cell, added the intermediate results and getting the output signal sample, and then the algorithm gives:  number of cells: = m.  running time: clock periods = m.  commutative product-type measures: (m) m.  efficiency and utilization: 100%.  broadcasting of the error signal, this is propagated to all cells.  the throughput rate of the 2-d lms array is the same as the 1-d or conventional lms array (only for this case). the latency time is reduced because the data that passes through the pipe for processing, takes short path (less number of cells (m 1/2 ) than the first pipe that has m cells), therefore, the amount of time the data stays in the pipe (of m 1/2 cells) is less than the time that the data stays in the pipe (of m cells). the overall computation time is: to = (2 t + 2 t+)m …(12) where t & t+ are the necessary times to compute one multiply and one add operations. riyadh a.h. al-helali al-khwarizmi engineering journal, vol. 5, no. 1, pp 83-93 (2009) 88 … … … … … d5 d9 d6 d8 d7 d0 d4 d1 d3 d2 + + + + + y0 y4 y1 y3 y2 y5 y9 y6 y8 y7 … … … … … … … … … … … “0” ”0” ”0” ”0” ”0” u0 u4 u1 u3 u2 u5 u9 u6 u8 u7 … … … … … (a) (b) fig. 3. (a) (2-d) systolic array realization of lms algorithm. (b) functional specification of a pe. a8 a8 a8 a8 a8 a1 a3 a3 a3 a1 a1 a2 a3 a2 a3 a2 a2 a0 a2 a1 a1 a0 a0 a0 a0 u a a u' e y u e procedure 2-d lms begin uh:= uh ; ei:= ei ; q := uh; m:= qei; ŵk:= ŵk + m yi:= yi + ŵkuh end riyadh a.h. al-helali al-khwarizmi engineering journal, vol. 5, no. 1, pp 83-93 (2009) 89 f ig . 4 . 3 -d sy sto lic a r r a y o f th e siz e 3  3  3 fo r th e l m s a lg o r ith m (fo r m = 9 ). (a ) th e g e n e r a l str u c tu r e a n d th e in te r c o n n e c tio n p a tte r n o f la y e r s. (b ) t h e la y e r str u c tu r e o f th e 2 -d p ie c e w ise r e g u la r a r r a y o f l m s a lg o r ith m . a 2 a 8 a 5 a 1 a 4 a 7 a 0 a 3 a 6 + + + d 8 d 5 d 2 d 6 d 3 d 0 d 6 d 3 d 0 + _y 0 y 3 y 6 d 7 d 4 d 1 + + + y 0 y 3 y 6 y 1 y 4 y 7 a 2 a 2 a 2 a 1 a 1 a 1 a 0 a 0 a 0 y 2 y 5 y 8 u i u i u i u 0 u 3 u 1 u 4 u 2 u 5 0 0 (a) (b ) riyadh a.h. al-helali al-khwarizmi engineering journal, vol. 5, no. 1, pp 83-93 (2009) 90 4.3 systolic array to increase the throughput rate by simulating the data flow that enters the 2-d semi-systolic array realization of lms algorithm designed of figure (3), to improve the time parameters (throughput rate), five data items were entered into the array simultaneously, broadcasting to the input of the five lower cells. then by computational activities of the simulation, the array gives that:  number of cells: = (pi)m, or the area complexity is o(pim), where pi, represents number of the parallel inputs to the array (here, pi = 5).  running time: clock periods = m.  commutative product-type measures: (pim) m.  efficiency and utilization: 100%.  broadcasting of the pi parallel inputs signal, error signal, which are propagated to all cells.  throughput rate has been improved, from the operation of the array, for each number of data outputs (n), there are sets of data inputs, which entered simultaneously into the array. therefore, the time complexity is o(n/pi). the input signal enters the first cell of the array and exits from the last cell of the pipe of the array. after applying the computational activities in the (m) cells, the latency is the same as in the classical case: o(m). 4.4 systolic array for improving the latency and throughput by combining the last two 2-d lms systolic arrays, a 3-d multilayered lms systolic array was obtained, which improves the two above features. the simulations of data flow and computational activities for the array of figure (4) give:  number of cells: = (pi)m, or the area complexity is o(sj 2 ip ) = o(pim), where 2 ip , represents number of the parallel inputs to the array (here, pi = 3), (here, sj =3) and (sj pi = m).  running time: clock periods = m.  commutative product-type measures: (pim) m.  efficiency and utilization: 100%.  broadcasting of the pi parallel inputs signal, error signal, which are propagated to all cells of the 3-d systolic array with size 333 for 1-d lms systolic array.  throughput and latency are improved to achieve the requirements of the 3-d multilayered array design and equal to o(n/pi), o(m 1/2 ) respectively. from the obtained simulation results, an efficient 3-d systolic lms array algorithm design can be selected to represent the preferable systolic design. the throughput rate of the 3-d designed systolic array is greater than that of the architectures [16], [17], but smaller than that of the pipelined architecture [18]. in [18], drawbacks of broadcasting the input signal, the overall complexity are high and its output latency is equal to the fir filter length (i.e., l). thus our algorithm has single assignment form, l-cells, high throughput rate, 100% utilization, l 1/2 latency, l-clock periods for one sample block, and finally the flexibility in the design, which takes the inner product (convolution sum) )()( nunwh in the design consideration, which enables us to extract more than one algorithm for the same problem. 4.1.3 conclusions from the systolic arrays were designed and simulating the data flows entering into the arrays, we deduced the following conclusions:  various 2-d and 3-d systolic arrays of 1-d lms-based adaptive (fir) transversal digital filters were designed which can effectively be implemented using only local communications on a parallel system comprised of combinatorial circuits, clocked delay elements and distributed memory.  the technique described exploits the recurrence inherent in the application and is based on the convolution sum (inner product ŵ h (n). u(n)) in the lms algorithm, which gives flexibility of deriving more than one systolic algorithm from the basic systolic structure.  proposed systolic arrays for 1-d lms algorithm allow an increase in the number of processors to increase throughput rate and to reduce the latency that is not achievable using riyadh a.h. al-helali al-khwarizmi engineering journal, vol. 5, no. 1, pp 83-93 (2009) 91 the conventional systolic array synthesis method.  the final systolic array of lms-based adaptive transversal filter is simple and exhibit increased throughput rate and decreased the latency, which is 3-d regular systolic algorithm making it amenable to vlsi implementation and can be used for a large variety recurrence computations in signal and image processing. however, the output of our efficient adaptive transversal filter is delayed by m 1/2 samples, where m is the filter length.  unlike the other structures, the throughput is independent of the filter length, implying that lms adaptive fir filter systolic array with several hundreds of filter coefficients can be represented by a word-level systolic arrays (multibit numbers). a word-level systolic array considers the inner product step as a typical operation for various signal-processing operations. the future work on a 2-d lms adaptive nonrecursive (or fir) digital filters with excitation u(n1, n2), response y(n1, n2) and order of the pair (m1, m2) to extract a systolic array for the algorithm. similarly by taking the 2-d inner product step of the weight vector and the input vector as a basic systolic representation of the algorithm, it can be designed it by the dependence graph method. the 2-d lms algorithm can formulate as: e(n1 , n2) = d(n1 , n2) – y(n1 , n2) …(13) ŵ(n1+1,n2+2)=ŵ(n1,n2)+e(n1,n2)u(n1,n2) …(14) where d(n1,n2) is a 2-d desired response, and e(n1 , n2) is a 2-d error signal. by using iso-plane method considered, partition one of the four indices of the 2-d convolution sum to reduce the latency and, by the same method try to obtain an (3-d and 4d) lms algorithm which has improved throughput and latency features. systolic representation of the 2-d adaptive digital filters serves in many important applications such as reduction of noise in images, enhancement of edges in images, processing of geophysical signals and other geological applications [19], since continuous signals are encountered that are inherently (2-d). abbreviations del delay dir direction fir finite-impulse-response fft fast fourier transform ips inner product step is index space iso iso-plane lms least-mean square pes processor elements vlsi very-large scale integration symbols a* set of interconnection pattern d(n) desired response e expected value expected value e projection vector e(n) error signal vector h hermitian transposition m number of taps n set of nonnegative integer numbers o( ) the class of all functions pi parallel inputs t transposition t time of execution t+ time execution of the addition operation t time execution of the multiplication operation u(i) discrete-time series u(n) observation vector v* set of cells/processors w(n) weight-error vector ŵ(n) estimate value of the weight-error vector w* conjugate value of w w0 optimum tap-weight vector y(n) output signal vector z set of integer numbers z n dependence graph space z n-1 processor space riyadh a.h. al-helali al-khwarizmi engineering journal, vol. 5, no. 1, pp 83-93 (2009) 92 z* processor location d, dependence vectors  offset vector  step-size parameter  allocation ² variance  time schedule  basis vector basis vector acknowledgements the authors would like to thank the anonymous reviewers for their useful comments. 6. references [1] l. xiaojian and t. b. leonard, “highspeed systolic ladder structures for multidimensional recursive digital filters,” ieee trans. signal processing, vol. 44, no. 4, pp. 1048-1055, nov. 1996. [2] f. lorenzelli and k. yao, “a linear systolic array for recursive least squares,“ieee trans. signal processing, vol. 43, no. 12, pp.3014484, apr. 1992. [3] n. petkov, systolic parallel processing. elsevier science publishers, north holland, 1993. [4] t. p. plaks, “mapping regular algorithms onto multilayered 3-d reconfigurable processor array,“ ieee proceedings of the 32 nd hawaii international conference 0n system sciences, pp.1-10, 1999. [5] k. m. ty and a. n. venestanopoules, “a fast filter for real-time image processing,” ieee trans. circuits syst. , vol. cas-33, pp. 948-957, oct. 1986. [6] r. gnanasekaran, “2-d filter implementation for real-time signal processing,” ieee trans. circuits syst., vol. 35, no. 5, pp. 587-590, may. 1988 [7] w. luk and g.jones, “systolic recursive filters,” ieee trans. circuits syst., vol. 35, no. 8 pp. 1067-1068, aug. 1988. [8] s. sunder and v. ramachandran, “systolic implementation of multidimensional nonrecursive digital filters,” ieee trans. circuits syst. video technol., vol. 3, no. 6, pp. 399-407, dec.1993. [9] jm. jover and t. kailath, “a parallel architecture for kalman filter measurement update and parameter estimation,” automatica vol. 22, no. 1, pp. 43-57, 1986 [10] s. haykin, adaptive filter theory, englewood cliffs, nj: prentice-hall, 1986. [11] p. quinton and y. robert, systolic algorithms and architectures. prentice hall, masson, uk, 1991. [12] s. rao and t. kailath, “regular iterative algorithms and their implementations on processor arrays,” proc, ieee, vol. 76, no.3, pp. 259-282, mar. 1988. [13] j. teich and l. thiele, “partitioning of processor arrays: a piecewise regular approach,” integration, vol. 14, no.3, pp. 297-332, 1993. [14] r. a. h. al-helali, “systolic algorithms of lms, rls adaptive (fir) digital filters for adaptive channel equalization,” m.sc. thesis, univ. of baghdad, baghdad, oct. 2005. [15] a. v. oppenheim, and r. w. schafer, digital signal processing. london: prentice hall, 1975. [16] g. long, f. ling, and j .g. proakis, “the lms algorithm with delayed coefficient adaptation,”ieee trans. acoustic., speech, signal processing, vol. 37, pp. 1397-1405, sept. 1989; vol. 40, pp. 230-232, jan. 1992. [17] d. l. jones, “learning characteristics of transpose-form lms adaptive filters,” ieee trans. circuits syst. ii, vol. 40, pp. 745-749, oct.1992 [18] s. c. douglas, q. zhu, and k. f. smith, “a pipelined lms adaptive fir filter. architecture without adaptation delay,” ieee trans. signal processing, vol. 46, pp. 775-778, mar. 1998. [19] a. antonio, digital filters analysis, design, and applications mcgraw-hill, 1993. 93-83، صفحة 1، العدد 5مجلة الخوارزمي الهندسية المجلد رياض علي عبد الحسين (2009) 93 انمصفىفاث انمتعذدة األبعاد من انمعانجاث انمتىازيت نخىارزميت أقم مربع انمعذل نهمرشح انرقمي انمكيف راث االستجابت انمحذودة اإلخراج **باقر عبذانرسىل انهاشمي* رياض عهي عبذ انحسين انهالني اندايؼح انًستُصشٌح/ كهٍح انُٓذسح / لسى انُٓذسح انكٓشتائٍح * خايؼح تغذاد/ كهٍح انُٓذسح / لسى انُٓذسح انكٓشتائٍح ** انخالصت نخٕاسصيٍح يشتغ أدَى يؼذل (انخالٌا االَمثاضٍح فً خسى اإلَساٌ)تتضًٍ انًمانح تصًٍى يُظٕياخ تشكم يصفٕفاخ يٍ انًؼانداخ . إنى يُظٕيح يٍ انًؼانداخ انًتٕاصٌح (انًشتثح)انخٕاسصيٍاخ انشٌاضٍح انًُضًح (تحٌٕم)نهًششح انشلًً ٔرنك تاستخذاو طشٌمح تتًثٍم تألػتًاد ػهى يصفٕفح انًؼانداخ األحادٌح األتؼاد نهًششح انشلًً ٔانزي تذٔسِ ٌؼتًذ فً ػًهّ ػهى يدًٕع حاصم ضشب يصفٕفح ٔطشٌمح االستثاط انذاخهً تٍٍ ْزِ (انخالٌا)تى أشتماق يدًٕػح إَٔاع يٍ انًصفٕفاخ ٔانتً تشكم تشتٍة يُظى يٍ انًؼانداخ , اإلخشاج إٌ انضيٍ انًستغشق نهحصٕل ػهى لًٍح ٔاحذج لذ . (vlsi)" انخالٌا ٔانتً تدؼهٓا يًٓح االستخذاو فً دٔائش انتكايم انمٍاسٍح انكثٍشج خذا . تًصفٕفاخ راخ األتؼاد األحادٌح" أَخفض ٔكزنك يؼذل اإلخشاج لذ اصداد يماسَح , إٌ انًصفٕفح انثالثٍح األتؼاد ٔانًتؼذدج انطثماخ تتأنف يٍ طثماخ ثُائٍح األتؼاد ٔانتً تشتثظ يغ تؼضٓا انثؼض ػٍ طشٌك انحافاخ فمظ إٌ يثم ْزِ انًصفٕفاخ نخٕاسصيٍح يشتغ أدَى يؼذل نهًششح انشلًً ًٌكُٓا تهثٍح االحتٍاخاخ فً تسشٌغ يؼذل االلتشاب نهُاتح انُٓائً فً . يؼظى تطثٍماخ انًششحاخ انشلٍح انًالئًح i al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 5, no. 4, pp 39-50 (2009) design and implementation of a telemetry system for environmental applications jabir s. aziz osama a. hussein department of electronic and communication engineering/ college of engineering/al-nahrain university. (received 9 march 2008; accepted 29 october 2008) abstract the environmental data acquisition telemetry system is a versatile, flexible and economical means to accumulate data from multiple sensors at remote locations over an extended period of time; the data is normally transferred to the final destination and saved for further analysis. this paper introduces the design and implementation of a simplified, economical and practical telemetry system to collect and transfer the environmental parameters (humidity, temperature, pressure etc.) from a remote location (rural area) to the processing and displaying unit. to get a flexible and practical system, three data transfer methods (three systems) were proposed (including the design and implementation) for rural area services, the first method is an rf link which can be used for field applications and rural areas. the other two methods are based on the utilization of packet-switching network (gprs and internet networks) to transfer the collected data to the required destination. remote and master units which represents the break down of the three proposed system are designed and implemented keywords : telemetry, gprs, remote master units, wireless communications, tdm. 1. introduction fig. 1. block diagram of a telemetry system. jabir s. aziz al-khwarizmi engineering journal, vol.5 , no. 4 , pp 39-50 (2009) 40 the purpose of a telemetry system is to collect data at a place that is remote or inconvenient and to relay the data to a point where the data may be evaluated [1]. this process can be achieved via wire-line or wireless links. telemetry has the advantage of reducing the cost of manually reading, checking and controlling remote devices. when telemetry applications use wireless technology, additional benefits accrue. the use of wireless technology enables systems to be located virtually anywhere without depending on the telephone company for line installation [2, 3]. telemetry system has a wide range of applications such as [2, 4]: * environmental monitoring. * telemedicine. * space applications. * security applications. * utility meter reading. * load management. * vending machine management. * land mobile vehicles. most of today's telemetry systems consist of the sections shown in figure (1). 2. telemetry system categories in order to evaluate the type of communications required for a telemetry application, it is important to consider telemetry systems in specific categories, i.e.: (a) high integrity, high data throughput, continuous communications (b) high integrity, low data throughput, continuous communications (c) high integrity, low data throughput, intermittent communications (d) low integrity, high data throughput, continuous communications (e) low integrity, low data throughput, continuous communications (f) low integrity, low data throughput, intermittent communications category (a) may require a quality microwave link, fiber optic cable or dedicated digital tie line service. category (b) may require a quality radio link, data quality copper cable or dedicated analog data tie line. category (d) may require connection into a lan or an isdn connection. category (e) may require connection into a radio link, on-site telephone cabling or analog tie line. categories (c) and (f), the application would involve a master site accessing the remote terminal units (rtus) at regular intervals of greater than 10 minutes, or at irregular intervals, of anything from 10 minutes to several days [5]. by placing a telemetry application into one of these categories, it is possible to determine the most appropriate and cost effective communications link solution it is often more appropriate to implement this category of telemetry system over an existing radio system, the major advantage of such an implementation is the significant cost savings, in not having to design and install new master site radio equipment [6]. 3. the proposed telemetry system a practical environmental telemetry system is proposed to collect the environmental parameters (humidity, temperature, pressure etc.) from a remote location (rural area) to the processing and displaying destination. the transmission channel was represented by three proposed data transfer methods:  rf link which can be used for field applications and rural  areas where the gsm and internet networks don't exist.  intranet over gprs network.  internet over gprs network. thus three scenarios can be provided for data transfer from the remote unit to the master unit at the required destination. figure (2) represents three scenarios of the designed and implemented telemetry system. 4. design and implementation the designed and implemented telemetry system consists of three scenarios, for scenario one it can be classified into category (f) since the data to be measured has a low rate of change. this system was set to transmit two channels each of 8 bit resolution and can be extended to 16 channels; these channels will be transmitted on periodic basis (15 minutes for each). jabir s. aziz al-khwarizmi engineering journal, vol.5 , no. 4 , pp 39-50 (2009) 41 fig. 2. three scenarios of the designed and implemented telemetry system. design and implementation of the remote, master and communication channel is illustrated in this section, through the following scenarios: i . scenario one: data transfer via rf this scenario can be described through the remote and master units as shown in figure (2-a). jabir s. aziz al-khwarizmi engineering journal, vol.5 , no. 4 , pp 39-50 (2009) 42 a. remote unit the remote unit consists of the following sections: i. data collection and signal conditioning section the circuit shown in figure (3) was build to achieve the functions of sensing, data collection and signal conditioning, in which lm35 is used as a linear temperature sensor, a/d 0804 and opamp are used as the data collection and signal conditioning section. the circuit is practical and generic i.e. the lm35 can be replaced by other sensor. ii. tdm multiplexing section two channels each of 8 bits are the input of the multiplexing section; tdm id technique is used as the multiplexing technique with 4 bits as the id of each channel thus the ability to address up to 16 channels. pic16f84a microcontroller is used with tri-state buffers (74244) as the controller section.; the microcontroller is also used to control the transmission period. figure (4) represents schematic diagram of the multiplexer and controller section. fig. 3. data collection section. fig. 4. schematic diagram of the implemented remote unit. jabir s. aziz al-khwarizmi engineering journal, vol.5 , no. 4 , pp 39-50 (2009) 43 iii. transmitting section the carrier frequency used in this process is 433 mhz with 20 mwatt as transmitter power, when using whip antenna of 15 cm the max distance is 300 meters of isotropic transmission; the max. distance can be extended either by using directional antenna such as the yagi antenna or by using rf power amplifier. tws-433 which is off-the-shelf hardware is used as the transmitter; it is ask, 433 mhz modulator with its compatible encoder ht-12e (it converts 4 parallel bits at input to serial output). figure (5) shows the tws and rws modules. holtek is the manufacturer of the modulator (tws-433) it has a wide product line which includes the same modulators with different operating frequencies; this provides the flexibility to change the operating frequency easily just by changing the modulator, and even to provide diversity facilities. figure (6) shows the implemented remote unit. fig. 5. rws-tws modules. fig. 6. the implemented remote unit. b. transmission channel free space is the propagation media for this scenario. maximum range depends on the transmitted power, frequency and the gain of the transmitting and receiving antenna. jabir s. aziz al-khwarizmi engineering journal, vol.5 , no. 4 , pp 39-50 (2009) 44 c. master unit it receives the collected data from the remote unit and it consists of the following sections: i. receiving section rws-433 receiver module is used with compatible decoder ht-12d to convert the serially received data into frames of 4 bits. whip antenna or directional antennas can be used at the receiver unit. ii. tdm de-multiplexing section de-multiplexing can be achieved using hardware or software methods; for the designed and implemented unit, software processing was used to de-multiplex the received data according to their channel id as shown in table-1. table 1, channel ids channel number channel id channel 1 1010 channel 2 0101 iii. data processing and display section it is the final stage in the master unit; it will provide monitoring and data archiving capabilities, it consists of: (1). interface sub-section it provides buffering and matches the electrical characteristics of the received data to the electrical characteristics of the parallel port of the pc; it also provides isolation and protection. (2). pc sub-section the receiver section is interfaced to the parallel port of a pc, thus the pc will be used to de-multiplex the received data by using software written in visual basic, performing error detection and correction algorithm, store the data in text, html, excel formats and provide terminal monitoring to the user. schematic diagram of the implemented master unit is shown in figure (7), the implemented master unit is shown in figure (8). fig. 7. schematic diagram of the implemented master unit. jabir s. aziz al-khwarizmi engineering journal, vol.5 , no. 4 , pp 39-50 (2009) 45 fig. 8. the implemented master unit. ii. scenario two: data transfer via intranet over gprs network this scenario utilizes the gprs network as the communication channel; the data was saved in the server computer of the remote unit and not sent to the master unit. the remote user (in the master unit) has the capability to browse the data, any user can access the data either by using a 3g mobile phone that supports web-browsing or by attaching the mobile device to the pc and using it as gprs modem and browse the data. this telemetry system can be classified into categories (d), (e) depending on the available b.w from the gprs service provider thus it can be high speed category (d) or low speed category. (e). a. remote unit the remote unit for this scenario consists of data collection section connected to the parallel port of a pc, web server application is installed on the pc (apache server) thus the stored data can be accessed using browsing technology. i. data collection section it is similar to the data collection section of scenario one. ii. multiplexing section binary data from the data collection section is fed to the parallel port of the pc where multiplexing is done in software written in visual basic thus data from different sensors is read and stored on the pc. iii. transmitter section mobile device is attached to the pc and by simple network settings the gprs services would be provided on the pc; thus the mobile device is used as gprs modem. b. communication channel gprs network is a packet-switched network; within this network small units of data called packets are routed through a network based on the destination address contained within each packet. every packet has to contain a header; the header for example contains information about the sender (source address) and the receiver (destination address) of the packet. this information is used in the network to route the packets through the different network elements. the gprs network overlays the existing gsm circuit switch http://searchnetworking.techtarget.com/sdefinition/0,,sid7_gci212736,00.html jabir s. aziz al-khwarizmi engineering journal, vol.5 , no. 4 , pp 39-50 (2009) 46 networks. the main goals of gprs network are to:  enable gsm network operators to operate packet data services utilizing the existing gsm radio infrastructures on a dynamic and flexible basis.  efficient use of bandwidth.  usually packet switching network charged by volume and not by time unit, for subscribers this has the advantage that they pay for downloading a web page but not for the time reading it [7,8]. this paper suggests establishing a local intranet between the gprs devices i.e. intranet between the private ip addresses of the network. by using the mobile devices as gprs modems for the workstation and pc’s which will communicate with each other and exchange data between other through this network, as shown in figure (9) where the workstation 10.3.0.124 can communicate with any other one where its requests will be forwarded to the appropriate destinations through sgsn whenever the destination inside the gprs network but if it outside the gprs network then this request will be forwarded to the ggsn where it’s the gprs gate to the out side network. fig.9. intranet connection between gprs devices over the gprs network. c. master unit for this scenario the master unit is any remote browser that is capable of browsing the remote unit, the remote browser can be a mobile device that supports browsing technology, or a mobile device connected to a pc thus using the pc to browse the data at the remote unit. it should be noted that the intranet connection is done between private ip addresses on the same network (the network of the gprs service provider) so data on the remote unit is not accessible from other networks. iii. scenario three: data transfer via internet over gprs network in scenario two it was shown that data at the remote units is not accessible from other network but from devices on the same gprs network, this scenario overcomes this limitation by using the mobile device to provide internet service at the remote unit and by using the logmein software that enables the access to the remote unit from any internet connection. for more info about the logmein check http://secure.logmein.com . scenario three can be classified into category (e). http://secure.logmein.com/ jabir s. aziz al-khwarizmi engineering journal, vol.5 , no. 4 , pp 39-50 (2009) 47 a. remote unit the remote unit used for this scenario is the same remote unit used in scenario two, the logmein software has been installed on the server of the remote unit in this scenario. b. communication channel any two computers can communicates with each other through internet; in order to provide direct access from one computer to another they should be assigned public ip addresses; using public ip addresses requires to rent a public ip address, and extra equipments equipments; although the application we are using (telemetry for environmental applications) does not require high speed connection or continuous connection. the logmein software is an application that allows direct computer access between two computers with private ip addresses on the internet. the logmein software application is installed on the pc of the remote unit which is provided with internet connection from the gprs network as shown in figure (10). c. master unit for this scenario the master unit is any remote browser (pc or mobile device), that is provided with internet connection; on start the logmein server in the remote unit will automatically connect the pc of the remote unit to the logmein site on the internet, the master unit would connect to the logmein site http://secure.logmein.com where it will find a link that connects it directly to the pc of the remote unit. the scenarios mentioned above can be used individually or a combination of more than one scenario according to user needs, figure (11) illustrates a telemetry system that uses rf link to collect data from remote unit and intranet over gprs network to relay data to remote users. fig.10. data transfer between pc's with private ip addresses over the internet. fig.11. rf is used to transfer data from the remote unit to the master unit, internet over gprs service is used to provide the data to the remote users. http://secure.logmein.com/ jabir s. aziz al-khwarizmi engineering journal, vol.5 , no. 4 , pp 39-50 (2009) 48 5. results for scenario one the transmitted and received data is shown in table-2. this table shows that the transmitted data was received successfully without any error and with acceptable time delay. for scenario two and three the transmitted data from the remote unit is shown in table-3; the received data is saved on the server pc in the master unit in html pages as show in figure (12). table 2, transmitted and received data for scenario one. input data at the remote unit transmission time (hh:mm:ss) received data at the master unit arrival time (hh:mm:ss) channel one (temperature) 101000 40 co 06:08:33 channel one (temperature) 101000 40 co 06:08:34 channel two (humidity) 00001101 13 % 06:08:36 channel two (humidity) 00001110 14% 06:08:37 table 3, transmitted data from the remote unit for scenario two and three. input data at the remote unit transmission time channel one temperature 40 co 15:01:21 channel two humidity 13% 15:01:43 channel one temperature 41 co 15:02:04 channel two humidity 14% 15:02:25 fig.12. received data from remote unit-a saved in html page in the master unit. jabir s. aziz al-khwarizmi engineering journal, vol.5 , no. 4 , pp 39-50 (2009) 49 6. conclusions this paper introduces the design and implementation of a flexible and practical telemetry system to collect and transfer the environmental data (temperature and humidity) from rural areas to the processing and displaying destination. the implemented system has the advantage of its simplicity, low cost, and easy to adapt with the available means of communication. the results of testing the different approaches (scenarios) give an accurate results and acceptable time response. this system can be considered as generic system which can be utilized for many other applications. 7. references [1] f. carden, r. jedlicka, r. henry, "telemetry systems engineering", artech house, 2002. [2] n.j. muller," wireless a to z", mcgraw-hill, 2003. [3] m.d. holt, general dynamics nis, "low power – low cost undersea telemetry system", ieee digital object identifier 10.1109/oceans.2005.1640182, 2000. [4] m.c. shults, r.k. rhodes, s.j. updike, b.j. gilligan, and w.n. reining, "a telemetryinstrumentation system for monitoring multiple subcutaneously implanted glucose sensors", ieee trans. biomed. eng., 41: 937– 942, 1994. [5] d. bailey, et al.," radio engineering and telemetry for industrials", newnes, 2003. [6] john g., webster," electrical measurement, signal processing and displays", crc press, 2004. [7] basavaraj patil, et al. "ip in ….wireless networks", prentice hall ….ptr, january 31, 2003. [8] norterl networks, "univity gsm ….sgsn gprs core network ….solutions" product/service bulletin, 2005. 50 -39، صفحة 4، العذد 5هجلة الخىارسهي الهنذسية الوجلذ جببز عشيش (200 9) 50 تصوين وتنفيذ نظبم جوع بيبنبت لتطبيقبت بيئية اسبهة حسين جببز عشيش جبيعت انُهزٌٍ / كهٍت انهُذطت/ قظى هُذطت االنكخزوٌ واالحصبالث الخالصة ٍْ انىٌهتوصي ًٌثم جًع انبٍبَبث انبٍئًاٌ َظبو حّظظبِث انًخعّذدِة فً انًىاقعِ انبعٍذِة عهى فخزة ث إقخصبدٌت ويزَت وُيخَعّذدة اإلطخعًبل نخَجًٍع انبٍبَبِث ِي ٍْ انًحطبث انطزفٍِت انبعٍذِة . ٌيث الححتِ عبدة عهى حبطىِة نهخحم انًظخهًت حخشٌ انبٍبَبثَ ;سيٍُت ىٌهتِ انُظبو انخحهٍذي ٌَْشًُم يحطت يظخهِى وواحذ أَو انعذٌذ ِي ٍْ يحطِت انًظخهىَ ث حًال ٌُ انبٍبَبَث عهى حبطىةجىحَظج. قع عٍذاًا ِي حَظخهُى انًحطت انطزفٍتُ انبعٍذةُ . ُة يحطتُ انًظخهَى انًحطت انطزفٍتَ انبعٍذةَ شكم يخظهظم وحَْخش ْخخَهِفت حُحبُص وانًعهىيبَث عىايمال. انًخحظظبثإشبرةُ اإلطخجىاَة انخً حَْبذأُ حظهظم ًُ يشبركخهب يعبنجت ولرَطهت عٍ زٌق وصهِت آر إف إنى يحطِت انًظخهَى لثُ ان .عبز شبكت حبطب بث ع انبٍبَبِث انضزورٌِت، و ًْ ٍْ يحّظض واحذ ًٌكٍ أٌ ٌُظخَعًَم نَج ثبل فً هذا ثفً انًحطت انطزفٍِت انبعٍذِة، أكثز ِي ًِ حّظظبث انز ى تَ ودرجتَ انحزارة أُِخذا َك . انعًمِ . إلْرطبل انحُىاِث انًخخهفتِ ديجحً دي إو وحً دي إو أي إخخزا كخحٍُبث ٍْ زٌحت واحذة (خبدو) انبٍبَبُث ٍٍ انًحطت انطزفٍِت انبعٍذِة ووحذِة انًظخهَى ارطبل انًعهىيبث ، واحذة آر إف وصهتإحّصبل يببشز، )أَُجشا أكثز ِي . ( آر إفوصهخً واإلَخزَِج عبوإَخزاَج، جً إص إو، اإلَخزَج عُىاٌ آي ً) واحذة بكثز يٍ زٌحتوانش ىٌ أَُجَش خيل شبكت (خبدو) انبٍبَبُث ٍٍ وحذِة انًظخهَى حببدل .( عُىاٌ آي ً خباِّص 12-25 al-khwarizmi engineering journal,vol. 12, no. 4, p.p. path planning of an autonomous optimization technique ibraheem kasim ibraheem * ,** department of electrical engineering / *email: (received http://dx.doi.org/10.22153/kej.2016.08.002 abstract this paper presents a meta-heuristic swarm natural activities of actual ants inspire which named to find the shortest and safest path for nonzero size for the mobile robot has been considered for the actual size of the mobile robot further modifications. simulations results, which carried out using matlab suggested algorithm outperforms the standard version of aco algorithm for the same problem with the same environmental conditions by providing the shortest path for multiple testing environments. keywords: robotics, path planning, ant colony optimization, static environment, and collision 1. introduction route forecasting is a vital part of steering of the mobile robot; it is recognized obtaining an enhanced collision-free path from the initial point toward destination station. in computational complexity theory, route forecasting is categorized as an np (nondeterministic polynomial time) comprehensive problem. that is, the computational time that is required to solve such problem rises dramatically (typically exponential rate) while the size (or dimension) of the problem raises. the researche forecasting begin in late 60's, algorithms have been proposed, comprising the roadmap method, cell decomposition, potential fields, and mathematical programming, etc. it has been found that these methods are either ineffective, due to the significant cost; or imprecise, due to the trapping in local minima. to overcome these drawbacks khwarizmi engineering journal,vol. 12, no. 4, p.p. 1225 (2016) path planning of an autonomous mobile robot using optimization techniques ibraheem kasim ibraheem* fatin hassan ajeil electrical engineering / college of engineering / university of baghdad email: ibraheemki@coeng.uobaghdad.edu.iq **email: fatin.hassan0@gmail.com (received 19 april 2016; accepted 23 august 2016) http://dx.doi.org/10.22153/kej.2016.08.002 heuristic swarm based optimization technique for solving robot path planning. the which named ant colony optimization. (aco) has been proposed in this work a mobile robot in different static environments with different complexities. a been considered in the project by taking a tolerance around the ob for the actual size of the mobile robot. a new concept was added to standard ant colony optimization ( simulations results, which carried out using matlab 2015(a) environment, prove that the suggested algorithm outperforms the standard version of aco algorithm for the same problem with the same environmental conditions by providing the shortest path for multiple testing environments. ing, ant colony optimization, static environment, and collision route forecasting is a vital part of steering of s recognized as the art of free path from the initial point toward destination station. in computational complexity theory, route ng is categorized as an np (nondeterministic polynomial time) problem. that is, the computational time that is required to solve such problem rises dramatically (typically at an exponential rate) while the size (or dimension) of researchers of route and several algorithms have been proposed, comprising the roadmap method, cell decomposition, potential fields, and mathematical programming, etc. it has that these methods are either computational cost; or imprecise, due to the trapping in local to overcome these drawbacks, many heuristic methods have been implemented, such as the application of artificial neura of the main benefits of heuristic algorithms is that it can produce an acceptable result very fast, which is especially suitable to solve np problems. the objective is to find the shortest and collision-free route (if the initial point and an end point in a network [1]. in [2], authors proposed two kinds of route forecasting in the robotic field. these techniques are identified as global route forecasting and path prediction. in global route have complete information about the situation this global path can aid the robot to navigate the real location because the feasible optimal route has been found within the location before robot start to navigate) whereas in local route forecasting robots do not have information about the situation or the information is not comprehensive (incomplete information). main difficulties for constructing route algorithms for mobile robots al-khwarizmi engineering journal (2016) mobile robot using swarm based ajeil** university of baghdad based optimization technique for solving robot path planning. the has been proposed in this work in different static environments with different complexities. a around the obstacle to account to standard ant colony optimization (aco) for environment, prove that the suggested algorithm outperforms the standard version of aco algorithm for the same problem with the same ing, ant colony optimization, static environment, and collision-avoidance. heuristic methods have been implemented, such as the application of artificial neural networks. one of the main benefits of heuristic algorithms is that it can produce an acceptable result very fast, which is especially suitable to solve np-complete problems. the objective is to find the shortest and the path exists) between an initial point and an end point in a network [1]. in [2], authors proposed two kinds of route forecasting in the robotic field. these techniques global route forecasting and local in global route prediction, robots have complete information about the situation this global path can aid the robot to navigate to the real location because the feasible optimal route has been found within the location before robot start to navigate) whereas in local route ing robots do not have information about the situation or the information is not comprehensive (incomplete information). the main difficulties for constructing route forecasting algorithms for mobile robots are efficiency and ibraheem kasim ibraheem security. efficiency means it should take best time and safety means avoiding collision with obstacles. the robot route forecasting could be classified into different kinds based on number of robot (single or multi robot environment (static or dynamic). the environment where the robot is situated, the route forecasting methods can be categorized into two kinds as shown in figure 1. fig. 1. classification of path planning based on environment. looking into figure 1, for each of these two kinds could be additionally divided into two sub classification depending on how much the robot recognizes the complete information of the surrounding locations: 1-robot route forecasting in a known environment in which the automation previously knows the position of the obstacles before it starts to navigate. 2robot route forecasting in a partially known or inexact environment in which the robot estimates the environment using sensors to get the local information of the location, shape and dimension of obstacles and then uses the information to ensure local path planning. in this paper, we present case 1 when the environment is static and known obstacles 2. related works many types of research studies path planning in recent years. [3] describes the use of algorithm to find the optimal path in environment; the mobile robot has to find the best route which decreases the number of stages to taken between the initial point and by allowing four-neighbor movements of robot. authors in [4] performed two types of path planning: global path planning using two versions of artificial bee colony (abc) and local path planning by hybrid bacterial foraging optimization (bfo) and artificial potential field al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 13 should take best time means avoiding collision with forecasting methods into different kinds based on multi robot) or type of environment (static or dynamic). according on the environment where the robot is situated, the route forecasting methods can be categorized into classification of path planning based on looking into figure 1, for each of these two divided into two subclassification depending on how much the robot information of the robot route forecasting in a known environment on previously knows the position of the obstacles before it starts to in a partially known or inexact environment in which the robot estimates the environment using sensors to get the local tion of the location, shape and dimension of obstacles and then uses the information to we present case 1 when the obstacles. studies path planning [3] describes the use of a genetic optimal path in a grid the mobile robot has to find the best route which decreases the number of stages to be between the initial point and the end point neighbor movements of the authors in [4] performed two types of path planning: global path planning using two versions of artificial bee colony (abc) and local path bacterial foraging artificial potential field (apf) algorithms. while the implementation of the particle swarm optimization (pso) to find optimum path, obstacle avoidance is done by translating robot to the adjacent safe point around the obstacle’s border which i calculated; this work has the researchers in [6] introduced path planning in a dynamic environment by combining heuristic algorithm and simulated annealing algorithms. the researchers in [7] implemented water drops (iwds) algorithm to solve robot route forecasting problem, the suggested algorithm has two stages; the first stage, finds path. the second stage relatively close distances of decreases its length and response yogita et al. describe the use of two metaheuristic algorithm based on solitary intelligence cuckoo search algorithm (bs) algorithms. they are used planning for robot in the same static environment contain twenty obstacles, and assume that the robot move with theta and distance from source station toward destination, they assume that robot encounters obstacle, it will back one size and choose new position that satisf minimum distance with destination, the simulation result showed that the bat search outperforms the cuckoo search in term of number of iteration and complexity of the environment. chih et al. implemented artificial immune system (ais) which is based on natural immune system ability to detect cells foreign to the body it has been used to construct initial feasible shortest path for mobile robot from start point to the end after that they smooth by applying most effective curve interpolation called b-spline interpolation implemented for the work was only static obstacle, the simulation results show the effectiveness of the proposed algorith shape environment. several algorithms have this purpose, ant colony optimization (aco) is one of the most used algorithm organized as follow: section 1 introduction, work, section 3 ant colony optimization, section 4 modeling of the environment, problem definition, section based robot path planning discussion, section 9acknowledgement, and 10 khwarizmi engineering journal, vol. 12, no. 4, p.p. 1225(2016) algorithms. while the implementation of the particle swarm optimization (pso) to find the path, obstacle avoidance is done by translating robot to the adjacent safe point around the obstacle’s border which is pre-defined and has been presented in [5]. the researchers in [6] introduced path planning in environment by combining heuristic algorithm and simulated annealing algorithms. the researchers in [7] implemented intelligent water drops (iwds) algorithm to solve robot route forecasting problem, the suggested algorithm has stage, finds the best global does a local search at relatively close distances of the global route and s its length and response time. in [8] g. describe the use of two metaheuristic algorithm based on solitary intelligence, these are cuckoo search algorithm (cs) and bat search they are used to find global planning for robot in the same static environment contain twenty obstacles, and assume that the robot move with theta and distance from source destination, they assume that if the obstacle, it will back one step size and choose new position that satisfies minimum distance with destination, the simulation result showed that the bat search outperforms the cuckoo search in term of number of iteration and complexity of the environment. in [9] h. hsumplemented artificial immune (ais) which is based on natural immune system ability to detect cells foreign to the body. to construct initial feasible shortest path for mobile robot from start point to the end after that they smoothed the resulting path by applying most effective curve interpolation spline interpolation. the environment implemented for the work was a grid and contain only static obstacle, the simulation results show the effectiveness of the proposed algorithm in iseveral algorithms have been suggested for this purpose, ant colony optimization (aco) is algorithms. this paper is introduction, section 2 related ant colony optimization, section of the environment, section 5 ection aco and maco based robot path planning, section 7-result, and 8 conclusion, 10-references. ibraheem kasim ibraheem 3. ant colony optimization (aco) algorithm aco is a met heuristic method that belongs to the arbitrary searching algorithm. this algorithm was firstly introduced by m. dorigo [ made the complete use of the likenesses between the routes of ant colony searching for food and the well-known travel salesman problem (tsp). to solve the tsp by an artificially simulating the procedure of ant searching for the food, discovery the shortest route from ant nest to food places through the interchange of information collaboration [11]. all ants of the move along the same path by following one another. this is because every ant substance called “pheromone” while moving. the other ants sense the intensity of pheromone and follow the path having a higher concentration of pheromone. this is their way to find an optimized path. initially, the ants wander randomly to find their way to the destination. every pheromone along the route. on their back tour ant senses pheromone intensity and choose the path having a higher concentration of pheromone. the pheromone evaporates with time and hence the concentration of pheromone would be higher along the shortest path as the time taken to cover the shortest path would be minimum as comp to other paths. hence, almost every ant would be attracted by the higher intensity of pheromone along the shortest path and select the optimized path. pheromones: biochemical material left by an ant when traveling; separately ant probabilistically favors to follow route rich in pheromone relatively than a lesser one [12 if the ants encounter obstacle, they travel into available paths with equal probability ( pheromones) as shown in the figure below: fig. 2. ants obstacle avoidance al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 14 ant colony optimization (aco) aco is a met heuristic method that belongs to the arbitrary searching algorithm. this algorithm by m. dorigo [10] who made the complete use of the likenesses between earching for food and the problem (tsp). to solve the tsp by an artificially simulating the procedure of ant searching for the food, discovery the shortest route from ant nest to food places of information and shared the same anthill move along the same path by following one ant releases a substance called “pheromone” while moving. the other ants sense the intensity of pheromone and ath having a higher concentration of their way to find an optimized the ants wander randomly to find their way to the destination. every ant releases . on their back tour ant ensity and choose the path of pheromone. the pheromone evaporates with time and hence the concentration of pheromone would be higher along the shortest path as the time taken to cover the shortest path would be minimum as compared . hence, almost every ant would be attracted by the higher intensity of pheromone along the shortest path and select the optimized path. pheromones: biochemical material left by ; separately ant ors to follow route rich in relatively than a lesser one [12]. if the ants encounter obstacle, they travel into available paths with equal probability (re-initialize pheromones) as shown in the figure below: ants obstacle avoidance. 3.1. mathematical model of algorithm [13] 1-for kth ant at node i and want to move to next node j using probability formula. ������ � � �� �∗� ��� � � � �� �∗� ��� �� ��� where � & � are degree of importance of pheromones and heuristic function respectively. 2-after the ants complete their tour, the pheromones trial values are update the following formula: ����� � �� � �1 � �!���� where is the pheromones decay parameter range (0, 1) ∆��� : is the amount of pheromones added by ant. ∆��� � ∑ ∆���. ^�&'() ∆���.'� */,���-!! where q is pheromones update constant, the performance index needs to 3.2. modified ant colony optimization algorithm (maco) the optimal path is the main component of the robotics domain, is the specific criteria such as distance, this problem solved by using optimization algorithm such as ant colony optimization (aco), is added to standard aco called approach to alleviate stagnation is pheromone control. pheromone control adopts several approaches to reduce the influence and encourage the exploration of new paths that are non-optimal. aging: a past experience controlling the amount of pheromone for each ant according to its age. this known as aging. in aging, and lesser amount of pheromone as it moves from one obstacle to another obstacle on the rationale that old ants are less successful in locating the optimal paths since they take time to reach their destination. both aging and evaporation encourage discoveries of new that are previously non-optimal since the amount of pheromones deposit by every ant is giver by eq. (4), that’s mean the varying with corresponding to ants age, the suggested equation to change the amount of pheromones is given by: khwarizmi engineering journal, vol. 12, no. 4, p.p. 1225(2016) mathematical model of the aco and want to move to next node j using probability formula. � … (1) are degree of importance of pheromones and heuristic function respectively. after the ants complete their tour, the are updated according to ��� � ∆��� … (2) is the pheromones decay parameter in : is the amount of pheromones added by ant. … (3) … (4) is pheromones update constant, fitness is the performance index needs to be minimized. ant colony optimization path is the main component of the robotics domain, is the path needed to satisfy specific criteria such as distance, this problem is by using optimization algorithm such as ant colony optimization (aco), the new concept to standard aco called aging. the approach to alleviate stagnation is pheromone ntrol. pheromone control adopts several approaches to reduce the influence of experience and encourage the exploration of new paths that experience can also be reduced by controlling the amount of pheromone deposited ant according to its age. this approach is known as aging. in aging, an ant deposit lesser and lesser amount of pheromone as it moves from other obstacle. aging is based on the rationale that old ants are less successful in optimal paths since they take a longer time to reach their destination. both aging and evaporation encourage discoveries of new paths optimal [14]. since the amount of pheromones deposit by every by eq. (4), that’s mean the ∆��� is varying with corresponding to ants age, the suggested equation to change the amount of ibraheem kasim ibraheem al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 1225(2016) 15 *& � *&./ � 0�1230�45 6 × 89�: � 0�1230�45 ; × m … (5) where *&./ is the upper limit of pheromones and *&�= is the lower limit of pheromones, m is the total number of ants, and m is the index of ant in the colony. 4. mobile robot environment modelling the first phase of route forecasting is to create an environmental model for the 2-d workspace of the mobile robot. there are several approaches of environment forming: grid-based method and free space-based method. each of these methods has advantages and disadvantages. 4.1. grid-based method this environment is represented by a grid of (usually square) cells; each cell is either traversable or obstructed object (on a traversable cell) can move to any adjacent traversable cell. the features of the grid-based method it is conceptually simple representation, local changes have only local effects, well suited for dynamic environments. limitation of grid-based method are: imprecise representation of arbitrary obstacle increased resolution in one area increases complexity everywhere (potentially large memory size) as shown in figure 3 below: (a) (b) (c) fig. 3. (a) grid-based method with resolution (1), (b) grid-based method with resolution (5) (c) grid-based method with resolution (10). 4.2. free space-based method the environment is an initially empty simple shape, represent obstacles as virtual circle, advantages: arbitrary polygon obstacles, arbitrary motion angles, and unlimited resolution so memory is efficient. limitations of the free spacebased method are: complex code, point localization takes more than constant time, and a waste of space (see figure4). ibraheem kasim ibraheem fig. 4. free space-based method. in this paper, we present path planning in binary grid method, each cell in the occupancy grid has a value representing the occupancy status of that cell. an occupied location as true (1) and a free location is represented as false (0). 5. problem definition assume a 2-d square map covered with a uniform arrangement of net points. the size of the environment can be changed randomly; here, the environment comprises of a 10 ×10, 20 × 20, 30×30, and 40×40 grid cell. the left highest place of the environment is the beginning point for a route while the right lowest place of the environment is the end point for a route. the shapes and the size of an obstacle are variable, the positions of the obstacles are arbitrarily closed and can be located at any network locatio map excepting at locations adjacent to the initial position region or adjacent to the destination region (let two grid location left). also, several obstacles are possible below shows an example of such a procedure. since the mobile robot is not a point, the dimension of the robot is added to the of an obstacle to ensuring the safety while piloting in the environment as displayed in figure 5. al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 16 based method. in this paper, we present path planning in each cell in the occupancy grid has a value representing the occupancy status of that cell. an occupied location is represented is represented d square map covered with a uniform arrangement of net points. the size of the randomly; here, the environment comprises of a 10 ×10, 20 × 20, 30×30, and 40×40 grid cell. the left highest place e beginning point for a route while the right lowest place of the environment is the end point for a route. the shapes and the size of an obstacle are variable, the are arbitrarily closed at any network location in the adjacent to the initial position region or adjacent to the position grid location left). possible; figure 4 below shows an example of such a procedure. bile robot is not a point, the is added to the dimension safety of robot while piloting in the environment as displayed in fig. 5. expanding the size of corresponding to robot size in the figure above the size of enlarge by the radius of the beginning from the net position (1, 1) iteratively travels from its current location to one of its surrounding locations (row, col), ant a can select the next location (j) by selecting one of its 8 surrounding j-1), (i+1, j), (i+1, j+1) ...] …c, where is the set of all surrounding nodes of the current node. the ant a takes its next nod founded on the probability given by equation (1) fig. 6. an ant searching the surrounding cells. the ant colony optimization algorithm is a joining product of positive response and some heuristic function. in ant colony optimization algorithm, ants select the route mainly depend on two stimulating message, the pheromone concentration and the visibility of ne concentration of pheromone does not have the large effect on the process in the process of algorithm. so, ant discovers enhanced solutions primarily according to the objective function. when used in route forecasting with grid model, the objective function is distance determined as follows: >��, �� � @ �a� � ab� 6 where g represents the goal node and the next node. khwarizmi engineering journal, vol. 12, no. 4, p.p. 1225(2016) expanding the size of obstacle corresponding to robot size in the figure above the size of obstacles is the robot (r). beginning from the net position (1, 1), an ant iteratively travels from its current location to one locations. when ant at node i (row, col), ant a can select the next location (j) by selecting one of its 8 surrounding locations: [(i+1, ), (i+1, j+1) ...] …c, where c typically is the set of all surrounding nodes of the current node. the ant a takes its next node arbitrarily, founded on the probability given by equation (1) n ant searching the surrounding cells. colony optimization algorithm is a joining product of positive response and some heuristic function. in ant colony optimization algorithm, ants select the route mainly depend on message, the pheromone concentration and the visibility of next node. the concentration of pheromone does not have the effect on the process in the early iterative . so, ant discovers enhanced solutions primarily according to the objective function. when used in route forecasting with grid model, the objective function is the shortest distance determined as follows: � �c� � cb� 6 … (6) where g represents the goal node and i represent ibraheem kasim ibraheem 6. aco and maco based planning the ant colony optimization technique can be applied to the robots to find an optimized path while navigating in an environment. artificial ant: are the mobile robot that is stimulated the natural ants. the moving of the is directed by a probabilistic function that depends on heuristic and trail functions. they transfer in the search space having all possible solutions and choose best solutions among them. artificial ant favors routes having larger pheromone concentration. the place of ants and quality of solution is recorded so that best solutions can obtained. flow code for maco algorithm [12] 1do for iteration=1, 2, …n initialization stage pre-initialize the taboo table of each ant and the pheromone intensity on all sides. each ant needs to choose the next destination based on the restriction of the taboo table. 2-do for ant=1, 2, …. k 3do for step=1,2, …. m 4-compute the probability of the kth ant’s next node using equation (1). 5if the next node occupied by obstacle neglect it else move to a next node by the computed probability store the history of past node locations in an array 6if the current location is equal to the end point? then obtain the path passed -update the pheromone evaporated on the entire map generated using equation (2) else go to step 4 end. 7. results and discussions 7.1. effect of design parameter in this section we present the influence of design parameter: number of iteration, ants, and evaporation factor (ρ) on global search the results are applying to 10×10, and 20 size as shown below: al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 17 robot path the ant colony optimization technique can be the robots to find an optimized path while navigating in an environment. artificial stimulated from . the moving of the artificial ants a probabilistic function that depends . they transfer in the search space having all possible solutions and choose best solutions among them. artificial ant favors routes having larger pheromone and quality of the so that best solutions can be aco algorithm [12] initialize the taboo table of each ant and the pheromone intensity on all sides. each ant needs to choose the next destination based on the restriction of the compute the probability of the kth ant’s next obstacle? then move to a next node by the computed probability store the history of past node locations in an array is equal to the end point? update the pheromone evaporated on re map generated using equation .1. effect of design parameters in this section we present the influence of design parameter: number of iteration, number of ρ) on global search. 10, and 20×20 map (a) (b) fig. 7. effect of no of iteration andexecution time for 10 map. from the previous figure, it's algorithm finds an optimal number of iteration, as shown in iteration (80) the path length are (15.07), (28.6274). time require is increased by changing the total numb colony from (5) to (50), it's obvious the number of ants should be increased with increased search space as shown in the figure below khwarizmi engineering journal, vol. 12, no. 4, p.p. 1225(2016) (a) (b) 7. effect of no of iterations on path length ×10 map, and (b) 20×20 from the previous figure, it's evident that the optimal path with increase total number of iteration, as shown in iteration (80) the path length are (15.07), (28.6274). also, the whole by changing the total number of ant in the (5) to (50), it's obvious the number of hould be increased with increased search space as shown in the figure below: ibraheem kasim ibraheem (a) (b) fig. 8. effect of no of ants on path length and execution time for (a) 10×10 map, and (b) map. from the previous figure, it's obvious best number for 10×10 map is (20), and for 20 map is (40). also, the total time require is increased. the best value of evaporation factor ( is between (0.3 to 0.7) for all dimension of space, and has no effect on computation time as shown in the figure below: al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 18 8. effect of no of ants on path length and 10 map, and (b) 20×20 obvious that the 10 map is (20), and for 20×20 the total time require is evaporation factor (ρ) r all dimension of search , and has no effect on computation time as (a) (b) fig. 9. effect of evaporation factor ( length and execution time for (a) 10 (b) 20×20 map. 7.2. aco and maco path planning results the results of implementing standard aco algorithm is introduced in this section. objective situations, four experiments showed. all with different complexity (size of search space, position, shape, and obstacle) experiments were done r2015 (a). the parameter setting table 1 below. for all the case studies the pheromone evaporation rate khwarizmi engineering journal, vol. 12, no. 4, p.p. 1225(2016) (a) (b) evaporation factor (ρ) on path length and execution time for (a) 10×10 map, and aco and maco path planning the results of implementing standard aco in this section. to make four experiments were . all with different complexity (size of search space, position, shape, and some an were done with matlab r2015 (a). the parameter setting is shown in table 1 below. for all the case studies the pheromone evaporation rate is set to =0.3. ibraheem kasim ibraheem al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 1225(2016) 19 table 1, parameter specification. 7.2.1. standard aco experiment (1) in this experiment the size of search space is (10×10) grid cell, and five obstacles are located in random manner for obtain the optimal path, its show that the shortest path is (15.07). the figures 10 and 11 shows the results of saco algorithm. fig. 10. best path found by standard aco for experiment 1. fig. 11. the convergence curve for experiment 1 from the previous two figure, the mobile robot start avoids static obstacles with the shortest path is (15.07) in iteration (78) with the total computation time equal to (1.217323) sec. experiment (2) in this experiment the size of search space is (20×20) grid cell, and ten obstacles are located in a random manner for obtaining the optimal path, its show that the shortest path is (28.63). the figures 12 and 13 shows the results of saco algorithm for experiment 2. fig. 12. best path found by standard aco for experiment 2. ibraheem kasim ibraheem al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 1225(2016) 20 fig. 13. the convergence curve for experiment 2. from the previous two figure, the mobile robot start avoids static obstacles with the shortest path is (28.63) in iteration (79) with the total computation time equal to (9.072979). experiment (3) in this experiment the size of search space is (30×30) grid cell, and obstacles are located in a random manner for obtaining the optimal path, its show that the shortest path is (45.9411). the figures 14 and 15 shows the results of saco algorithm for experiment 3. fig. 14. best path found by standard aco for experiment 3 fig. 15. the convergence curve for experiment 3. from the previous two figure, the mobile robot start avoids static obstacles with the shortest path is (45.9411) in iteration (97) with the total computation time equal to (52.853641). experiment (4) in this experiment the size of search space is (40×40) grid cell, and obstacles are located in a random manner for obtaining the optimal path, its show that the shortest path is (62.6690). the figures 16 and 17 shows the results of saco algorithm for experiment 4. fig. 16. best path found by standard aco for experiment 4 ibraheem kasim ibraheem al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 1225(2016) 21 fig. 17. the convergence curve for experiment 4 from the previous two figure, the mobile robot start avoids static obstacles with the shortest path is (62.6690) in iteration (96) with the total computation time equal to (134.770856). 7.2.2. modified aco (maco) experiment (1) in this experiment the size of search space is (10×10) grid cell, and five obstacles are located in random manner for obtain the optimal path, its show that the shortest path is (15.07). the figures 18 and 19 shows the results of maco algorithm. fig. 18. best path found by modified aco for experiment 1. fig. 19. the convergence curve for experiment 1 from the previous two figure, the mobile robot start avoids static obstacles with the shortest path is (15.07) in iteration (58) with the total computation time equal to (1.154530). experiment (2) in this experiment the size of search space is (20×20) grid cell, and ten obstacles are located in a random manner for obtaining the optimal path, its show that the shortest path is (28.63). the figures 20 and 21 shows the results of maco algorithm for experiment 2. fig. 20. best path found by modified aco for experiment 2. ibraheem kasim ibraheem al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 1225(2016) 22 fig. 21. the convergence curve for experiment 2 from the previous two figure, the mobile robot start avoids static obstacles with the shortest path is (28.63) in iteration (31) with the total computation time equal to (7.838582). experiment (3) in this experiment the size of search space is (30×30) grid cell, and obstacles are located in random manner for obtain the optimal path, its show that the shortest path is (45. 1127). the figures 22 and 23 shows the results of maco algorithm for experiment 3. fig. 22. best path found by modified aco for experiment 3. fig. 23. the convergence curve for experiment 3 from the previous two figure, the mobile robot start avoids static obstacles with the shortest path is (45.1127) in iteration (92) with the total computation time equal to (52.017160). experiment (4) in this experiment the size of search space is (40×40) grid cell, and obstacles are located in a random manner for obtaining the optimal path, its show that the shortest path is (61.8406). the figures 24 and 25 shows the results of maco algorithm for experiment 4. fig. 24. best path found by modified aco for experiment 4. ibraheem kasim ibraheem al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 1225(2016) 23 fig. 25. the convergence curve for experiment 4. from the previous two figure, the mobile robot start avoids static obstacles with the shortest path is (61.8406) in iteration (96) with the total computation time equal to (132.678247). table 2, comparison between standard aco and maco in term of path length and execution time. by looking to convergence curve for each map, we noticed the proposed algorithm is reached to global optimum faster than the standard version of the algorithm, and from table ii, the proposed algorithm requires less time, and path length either equal or less than the standard version. the time requires to solve problem increased dramatically with increasing search space, (from 1.217323 to 134.770856) sec for standard aco and (from 1.154530 to 132.678247) sec for modified aco; this is because non-deterministic polynomial nature of path planning as mention earlier. 8. conclusions this paper presented route forecasting of a mobile robot using a new proposed metaheuristic algorithm called the ant's age colony optimization. it reaches the goal using the capability of the optimization of ant system algorithm in the assumed stationary environment. the number of case studies has been directed by varying the number, size and position of the obstacle. the result is found to be best and satisfying for the individual problem with the parameters (α = 1, ρ= 0.3 and number of ant's m =50). with rising in the complexity of the problem, i.e. with an increase in some obstacles existing in the map; this algorithm will need a larger amount of execution time. 9. acknowledgement i would like to acknowledge all the staff of the electrical engineering department at baghdad university for their help. 10. 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[6] m. s. ganeshmurthy and g. r. suresh, "path planning algorithm for autonomous mobile robot in dynamic environment", international conference on signal ibraheem kasim ibraheem al-khwarizmi engineering journal, vol. 12, no. 4, p.p. 1225(2016) 24 processing, communication and networking (icscn), 3rd 2015. [7] s. sohaila et al." an intelligent water drops algorithm for solving robot path planning problem", ieee international symposium on computational intelligence and informatics, 2013. [8] g. yogita et al.," a comparison between bat algorithm and cuckoo search for path planning", international journal of innovative research in computer and communication engineering (ijircce), vol. 3, issue 5, may 2015. [9] h. hsu-chih et al. "a metaheuristic artificial immune system algorithm for mobile robot navigation",2014 tenth international conference on intelligent information hiding and multimedia signal processing [10] [10]-d. marco and s. thomas, "ant colony optimization', massachusetts institute of technology, 2004. [11] ying pei, "basic ant colony optimization", international conference on computer science and electronics engineering, 2012. [12] xin-she yang, "engineering optimization an introduction with metaheuristic applications", cambridge, united kingdom, 2010. [13] singiresu s. rao, "engineering optimization theory and practice", fourth edition, 2009. [14] g. yogita and g. kusum, "artificial intelligent in robot path planning", international journal soft computing and engineering(ijsce), issn:2231-2307, vol.2, issue.2, may 2012. [15] k. sapna, t.chhavi, y.deepak,and t. mayank," robot path planning in static environment using ant colony optimization", international journal of emerging trends in electrical and electronics(ijetee), vol. 5, issue. 3, july2013. �� 4ا���د، ����12 ا���ارز � ا���� �� ا���� ا �اھ�� �� � ا �اھ�� � ،2016( 25-12( 25 2�ر ���و �ت ا��$0�# � #��ام .�ارز ��ت ا, �اب ا* (��) '&%$ا�#�"! **&�57 526 ��4$ *أ �اھ�� �� � أ �اھ�� ��� ا��������� **،*���'�اد %�$#� /"!�� ا������ / ا� �� ibraheem151@coeng.uobaghdad.edu.iq : ا.� -�و+* ا�(�)� * fatin.hassan0@gmail.com :ا.� -�و+* ا�(�)�** الخالصة ��1-�0ام �(��#� ا25�ء +�23 ا�(�ا)� وا��� 6-����#9ا�8 ا�7��ر �!�و�9ت ا�?-�3< و=�ل $; ا.:�2ام �$ >bcد ا�d(ھ9 أ gh)ت ا���ف $; ا��=9ارز$� 5?� ا��?!� (�9�r$ 6cم %�)� ض�p ا، 5; ا�'oاء =9ارز$�� ا��?< ا.$7!�6 ا�-!�?n $; ا��!9ك ا�c >?�!� *#�)2* ا�(gh" =!�6 ا��?< "ا�l�اب ا.7$!�6 �-#��3ات n�?bp�r!-0$ ا�90ارز$�� ، )�x1p�ة v!5 +�(� ا�r�$9ن ا�th�يو 6r!-0$ ت�y�� *c ر��د ا�z� وا�!� $�d(ا ، �dhا� v9ت ا��اض�\ ]�d ا��و �$!� ا��و�9ت #$ �x �-����-�0ام ، +�23�6r:9 ا.:!* �!#9ا�8 ا�7� ]���$[ ا�?�p^ب��r�p �p ا��-+��3�ر+� $_ ، ?���وا�h: n-)x ا�90ارز$�� ا�?3-�]� `r�� ��!:.وف �!ا�90ارز$�� ا�aف وا��� ���r+اتo�r�p ر �#�ة��$ �zد ا��d(l. (microsoft word \344\310\321\307\3232740) al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 16, no. 4, december, (2020) p. p. 2740 studying the radial and tangential velocity components of the epithelization healing post photorefractive keratectomy surgery of the human eye nebras h. ghaeb department of biomedical engineering / al-khwarizimi college of engineering / university of baghdad email: nebras@kecbu.uobaghdad.edu.iq (received 23 january 2019; accepted 20 september 2020) https://doi.org/10.22153/kej.2020.09.003 abstract photorefractive keratectomy (prk) is the refractive technique that began with a physical scraping of the epithelial layer of cornea subsequent by laser treatment. post this procedure to about 48 hours the removed epithelial layer regenerated to protect the eye again. the regeneration process (called re-epithelization) started from the limbus of the cornea toward the central part of it. the re-epithelization mechanism consists of a change in cell density (mitosis) and cell concentration (migration) with a velocity in two directions: radial and tangential. in the present study, an estimation for both radial (responsible for the overlapped layers toward the outward direction of the cornea) and tangential components (contour shape wave from limbus to the center) has been done for the first time, not like the previous studies that always estimate the velocity values of the re-epithelization only. results showed that the trend shape of both components agrees with the kinematic behaviour of the mitosis and migration, where the maximum cell density fluctuated toward the central part in exponential decay shape. for a healing diameter of 2mm, the maximum redial velocity was 16.85 µm/h, while the maximum tangential velocity was 55.48 µm/h. these two components give a speed of reepithelization of 58 µm/h which agrees with the biological and practical healing speed measured of 60 µm/h. estimating these two components will open the way to understand the relationship between the total epithelial layer required and the total healing time to control the medication period for the patient post-surgery. keywords: re-epithelization, reaction – diffusion equation, prk, speed of healing. 1. introduction photorefractive keratectomy (prk) is the correction of the visual disturbance in refraction errors for nearsightedness, farsightedness, and astigmatism using some certain laser type. it was started earlier in the eightieth of the last century and approved to be used finally by the food and drug administration (fda) in 1996 [1]. medically this type of surgical procedure has the following steps: physical removing of the first layer of the cornea called the epithelial as it is a protective and regenerative layer, followed by applying the treatment laser that related in its energy to the refractive error shape and value, and finally protects the cornea with bandage contact lens until the epithelia build back and protect the cornea again. the epithelial building back process is called the reepithelization, which started from the limbus toward the central part of the cornea of the human eye. this process has been studied in many research works, to estimate its speed, and the encouragement factors affecting it, and sherratt and murray were pioneers in this field. nebras h. ghaeb al-khwarizmi engineering journal, vol. 16, no. 4, p.p. 2740 (2020) 28 in 1990 sherratt and murray [2] begun their work in mathematical modeling of the healing of an epidermal wound. the work presented the epidermal cell density, as a function of the wound radius of curvature and time, all which examined in the reaction–diffusion equation (rde), which state: in 1991 sherratt and murray [3] modified the simple rde to a coupled equation, by including the concentration of mitosis. the differential equations are for cell density, and rate of change in chemical concentration of epidermal growth factor (egf). the mathematical model of wound healing becomes: rate of variation in cell density, n = migration of cell + mitotic generation – natural loss …(2a) rate of variation of chemical concentration, c = diffusion of c + production of c – chemical decay ...(2b) and in differential form: �� �� = �∇�� + �� . �. �2 − � ��� − �� …(3a) �� �� = ��∇�� + ��� − �� …(3b) where s(c), the logistic regression is a function of chemical concentration, k, dc and λ are positive constants. ��� is a biological function. equations (3) have been solved for different clinical applications. in ophthalmology, the corneal epithelial mapping attracted in the last five years the researchers, especially, after the presenting of the ocular coherence technology (oct) system, which has the ability to measure and show the epithelial mapping [4]. dale et al, [5] rewrite equations (3) considering the corneal epithelialization and solved them to find the speed of the process. the effect of concentration and density with the presence of egf as a driving factor was considered. they proposed an analytical approximated solution verified by numerical scheme calculations. their findings direct us to the truth that the egf improves the healing rate or the speed of the traveling epithelial wave. the modified differential equations (based on equations (3) and customized for the epithelial corneal region) are: �� �� = ∇. ����� ∇� + �� � �� − � ��� − �� (4a) �� �� = ��∇�� + ��� − ℎ�� � − �� (4b) where dn(c): is the cell diffusion coefficient, h(c): cellular degradation, �, k, dc and λ are positive constants. equations (4) have been utilized as a starting point for the next research studies that deal with the re-epithelization of the corneal layer (see figure (1)). although these studies showed many aspects of interest but still no mentioned for the cell reepithelization velocity directions. these directions (radial and tangential) consist of the move of layers from limbus to the center in contour shape and toward the outward of the cornea to fully protect it again. estimating the velocity of each component alone needs more mathematical manipulation to predict the required time of full protection and manage the time of medication used during this period. rate of increase of cell density, n = cell migration + mitotic generation …(1) nebras h. ghaeb al-khwarizmi engineering journal, vol. 16, no. 4, p.p. 2740 (2020) 29 fig. 1. research studies regarding the re-epithelization of cornea. four imperative disciplines (as shown above) were reflecting the interest of the researchers in studying the corneal re-epithelization process. these disciplines are: a. mathematical modelling. the modeling here started by normalizing equations (4) with its boundary and initial conditions. then found a semi exact solution after considering sets of assumptions and simplifications [5, 6 and 7]. the final resulted manipulation may require a computer numerical scheme [5 and 11]. some solutions utilize wave theory to solve equations (4) [9, 10, 12, and 14]. b. biological studies. in such studies, the biological behaviour of the cell during the reepithelization has been considered. how to control the speed through certain corticosteroids and the expected time period for the healing process [8, 11, 13, 26, and 41]. moreover, study the cell kinetics during the whole healing process and compare between simulation program and real pathogenesis case studies [12]. the possibility of including few markers and measure the triggering signal from the stem cell to realize the optimum healing shape and rate [15, 21]. c. refractive outcomes. for the patients with low refraction error, the prk will be the treatment procedure (a safe surgery procedure). in such cases, the re-epithelization process will gain back the epithelial layer of about 50 µm which represents an extra power for the patient vision. during the healing period, the total thickness fluctuation and the visual outcomes also [13-19, 24, 26, 33-35, 38-40]. within the last few years after the invention of the epithelial mapping which described by the oct system many ophthalmologists begun to use it as an indication for the corneal abnormality such as dryness and keratoconus [23, 24, 27, 29, 31, 32-36, 41, 45, and 46]. d. pharmaceutical study. study the normal amount of the egf during the healing process and the possibility of utilizing some sort of pharmaceutical components to improve the supplied amount to the stem cell [5, 6, 11, and 24]. possibility of studying the α and γ – egf and their converse role during the reepithelization, with the impact of including antibodies [11, 15, 24 and 26]. assessment of effective gene and recognize the possibility of gene control to control the final healing shape and rate [43]. 2. mathematical model the differential equations (4) have been utilized here, applying the non-dimensionalize model recommended by dale [5], and using the following assumptions: a. the thickness of the epithelium is littler than the required length of healing, so the model will be two-dimensional form. b. by considering linear geometry of the wound healing or strip band form with long spatial domain length the equation will be solved in the semi-infinite domain of −∞ ≤ � < nebras h. ghaeb al-khwarizmi engineering journal, vol. 16, no. 4, p.p. 2740 (2020) 30 !" (treatment zone), and the solution will be one dimensional toward the x – direction. c. the original set of the axis is the wound boarder. d. the cellular diffusion coefficient changes linearly with egf concentration value (c). the new differential form will be: �� �� = � �# $�%� + & �� �#' + �%(� + &( ��2 − � − � (5a) �� �� = �� �)� �#) + *�2 − 5� − ,�� ��̂.� − �� (5b) where the dimensionless parameters have the following values: α = 0.01, β = 0.1, α1 = 0.9, β1 = 0.1, dc = 25, σ = 4000, µ = 1.37x104, �̂ = 3.02, δ = 110 and the wound length or the tz = 8 mm [4, 5, 6 and 7]. the initial and boundary conditions are biologically relevant to the surgical procedure or the prk process. figure (2) shows the center lines, wound center, epithelium boundary and the original point and axis. fig. 2. important notification on the human eye sketch. the boundary and initial conditions for the solution will be described graphically as shown in figure (3): fig. 3. initial and boundary conditions selected. bepi = boundary of epithelium, wc = wound center. horizontal center line vertical center line wound center e p it h el iu m b o u n d ar y origin treatment zone (tz) bepi wc x o –∞ on(x,0) = n oc(x,0) = c −∞ ≤ � < 0 n(x,0) = 0 c(x,0) = 0 0 ≤ � < 0 tz/2 = l initial conditions bepi wc x o –∞ on(x,t) = n oc(x,t) = c −∞ ≤ � < 0 (x,l) = 0xn (x,l) = 0xc � = 0 tz/2 = l boundary conditions nebras h. ghaeb al-khwarizmi engineering journal, vol. 16, no. 4, p.p. 2740 (2020) 31 3. proposed solution in the present work a solution for the final equations (5) has been suggested using the finite difference (fd) implicit method crank nicolson scheme (cns). the cns has the following definitions for the independent variable u, firstorder in time, second-order in direction (such as x) [16]: 1234512 ∆� = ( � 789 :.( ��, <, =, �1 �# , �)1 �#)� + 89 : ��, <, =, �1 �# , �)1 �#)�> …(6) each part of the differential equations (5) can be define according to the followings: = = ( � ?=9 :.( + =9 :@ …(7a) �1 �� = 1234512 ∆� (1st order in time for the independent variable u) … (7b) �1 �# = ( a∆# ?=9.( :.( − =95( :.( + =9.( : − =95( : @ …(7c) �)1 �#) = ( ��∆# ) �?=9.( :.( − 2=9 :.( + =95( :.(@ + ?=9.( : − 2=9 : + =95( : @� …(7d) the rearrangements and manipulation of the two differential equations, boundary and initial conditions will be done independently and then collect the final results as shown below: a. one dimensional reaction equation from equation (5a), rearrange the equation to be: �� �� = �%� + & �)� �#) + % ���� �#) + �%(� + &( ��2 − � − � …(8) equation (8) will be in cns form: �2345�2 ∆� = ( ��∆# ) b%?�9 :.( + �9 :@ + &cb?�9.( :.( + �9.( : @ − 2?�9 :.( + �9 :@ + ?�95( :.( − �95( : @c + d (e�∆# ) b?�9.( :.( − �95( :.( + �9.( : − �95( : @?�9.( :.( − �95( :.( + �9.( : − �95( : @c + b�9 :.( − �9 :c 7d4 � ?�9 :.( + �9 :@ + &(> b1 − ?�9.( :.( + �9 :@c …(9) b. one dimensional diffusion equation: from equation (5b), the cns form is: �2345�2 ∆� = gh ��∆# ) b?�9.( :.( + �9 :.(@ − 2?�9 :.( + �9 :@ + ?�95( :.( + �95( : @c + 7* �2 − 5?�9 :.( + �9 :@�> − ,��i 234.�i 2���i 234.�i 2� $�̂5��i 234.�i 2�' − *?�9 :.( + �9 :@..(10) initial conditions: �9� + �9( = �9� + �9( = 0 �jk 0 ≤ � < 0 …(11a) �9l��, 0 = �m n�o �9l��, 0 = �m j<ℎpk <ℎn� 0 ≤ � < 0 …(11b) boundary conditions: �9l��, 0 = �m n�o �9l��, 0 = �m j<ℎpk <ℎn� 0 ≤ � < 0 …(12a) for �#�0, < = �m n�o �#�0, < = �m �9.( :.( + �9.( : = �9q.( + �9 : n�o �9.( :.( + �9.( : = �9q.( + �9 : …(12b) c. speed of healing most of the studies regarding the speed of healing (u) started their modeling from the fisher reaction-diffusion equation [2, 5, 10 and 20]. the traveling healing wave solution uses the analogy of the relative coordinate system to predict the final expected form, which may be expressed as [5]: r = � s.gh t&�� 72�� �u.v � � − �� − �&> …(13) equation (13) has sets of constants that leads to a specific value of the healing speed of about 60 µm/h. the modification that has been added here to equation (13) is to suggest the shape of a solution that may analogy the trend of the solution in both of the cell density and concentration. this suggested analogy predicted from the mathematical interpolation of equations (9 and 10). the new modified shape of the healing speed (u) will be: rwmx = � s.gh t&�� 72�� �u.v � � − �� − �&>. p����.��� �sin ��mm − �mm …(14) where noo and coo are the cell density and egf concentration calculated from the above equations (9) and (10), as mentioned above for the state of constant speed of healing. d. velocity components (radial and tangential): the flow velocity of the re-epithelization process is measured and estimated to be in a micro scale [2, 3 and 4]. the reynold number, for this reason, is less than unity, and the flow could be considered as a creeping flow [43]. the description of the final equations for the two components velocity is: =\ = −r�j ] �1 − ^_ �\ + _` �\`� …(15a) =a = −r b�] �1 − ^_ a\ + _` a\`� …(15b) where the r and r, are the radius of curvature of the human cornea and new build-up layer thickness nebras h. ghaeb al-khwarizmi engineering journal, vol. 16, no. 4, p.p. 2740 (2020) 32 or the epithelial during the healing (see figure (4) for more details). fig. 4. radial and tangential direction with the start and end of epithelization. the final algorithm for the proposed solution discussed above from point (a) to point (f), can be summarized in the flowchart as shown in figure (5). fig. 5. proposed solution, equations here are discussed above from point (a) to point (f). start define the constant of solution: α = 0.01, β = 0.1, α1 = 0.9, β1 = 0.1, dc = 25, σ = 4000, µ = 1.37x104, �̂ = 3.02, δ = 110 and the wound length or the tz = 8 mm. define the initial values: �9m��, j , �9m��, j define the boundary values: �9 :�0, < , �9 :�0, < , �9 :�0, < , �9 :�0, < , solve eq.(9) to find �9 :.(��, < solve eq.(10) to find �9 :.(��, < use eq.(14) to find the modified healing speed: umod use eq.(15.a) to find the radial component healing speed: ur use eq.(15.a) find the tangent component healing speed: ur change the time increment from 4h to 40h. end nebras h. ghaeb al-khwarizmi engineering journal, vol. 16, no. 4, p.p. 2740 (2020) 33 4. results the numerical solution of reaction equation (9) and diffusion equation (10), with their initial and boundary conditions (11 and 12) have been done using the open-source scientific programming language octave (version 4.4.1). the solution of the above equations has been done after assuming the wound speed to be constant with a value of 60 µm/h [5]. in this step, both the cell density (n) and the variation in concentration (c) are evaluated from the limbus toward the center of the cornea. in the next step, an equation for the speed of the healing will be utilized to investigate the range and the shape of the wave speed of the healing process. this time the speed of healing will be examined with respect to the change of both n and c, which will decrease the total time period of the re-epithelization process (time of healing). after all the two components were assessed also based on the overall speed of healing. cell density and concentration the change in cell density (n(x, t)) is a sign for cell migration, mitotic activity, and natural loss. this is what concerned in equation (2) and related specifically to the wound re-epithelization of the corneal tissue. figure (6), shows the variation of cell density with regard to the direction of healing and time for the time period from 4 – 40 hours with ten steps changes. fig. 6. cell density for 10 steps of time with 4 hours per each, and through the length from the limbus to the center of healing (center of the eye). the change in chemical concentration of egf which represents the main drive for the proliferation for epithelial cell, figure (7) shows the change in concentration c(x, t) for 40 hours. fig. 7. cell concentration for egf for 10 steps of time with 4 hours per each, and through the length from the limbus to the center of the eye. speed of healing figure (8) shows the healing speed variation with respect to the egf concentration with a time of healing variation from 4 – 40 hours. fig. 8. speed of healing to the egf concentration for 10 steps of time. figure (9) shows the comparison between the first 4 hours with respect to the 12, 20, 28 and 36 hours. 0 0.2 0.4 0.6 0.8 1 0 0.2 0.4 0.6 0.8 1 c el l d en si ty n (x ,t ) x direction 04 hours 08 hours 12 hours 16 hours 20 hours 24 hours 28 huors 32 hours 36 hours 40 hours 0 10 20 30 40 50 60 70 80 90 100 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 e g f c o n c e n t r a t io n c (x ,t ) x-direction 04 hours 08 hours 12 hours 16 hours 20 hours 28 hours 32 hours 36 hours 40 hours 0 20 40 60 80 100 120 140 0 200 400 s p ee d µ m /h egf concentration ng/ml 04 hours 08 hours 12 hours 16 hours 20 hours 24 hours 28 huors 32 hours 36 hours 40 hours nebras h. ghaeb al-khwarizmi engineering journal, vol. 16, no. 4, p.p. 2740 (2020) 34 fig. 9. speed of healing with respect to the cell concentration of egf for 4 steps: (a) 12 h, (b) 20h, (c) 28h and (d) 36h compared with 4 hours. the radial component of the velocity described in equation (15a) shown in figure (10) below. fig. 10. radial speed of healing w.r.t the egf concentration for 10 steps of time. figure (11) shows the comparison between the first 4 hours with respect to the 12, 20, 28 and 36 hours. 0 5 10 15 20 25 30 35 0 100 200 300 400 500 600 s p ee d µ m /h egf concentration ng/ml after 04 hours after 12 hours 0 5 10 15 20 25 30 0 100 200 300 400 500 s p ee d µ m /h egf concentration ng/ml 04 hours 08 hours 12 hours 16 hours 20 hours 24 hours 28 hours 32 hours 36 hours 40 hours (a) 0 20 40 60 80 100 120 0 100 200 300 400 500 600 s p ee d µ m /h egf concentration ng/ml after 04 hours after 20 hours (b) 0 20 40 60 80 100 120 140 0 100 200 300 400 500 600 s p ee d µ m /h egf concentration ng/ml after 04 hours after 36 hours (d) 0 20 40 60 80 100 120 0 100 200 300 400 500 600 s p ee d µ m /h egf concentration ng/ml after 04 hours after 28 hours (c) nebras h. ghaeb al-khwarizmi engineering journal, vol. 16, no. 4, p.p. 2740 (2020) 35 0 1 2 3 4 5 6 7 8 9 0 100 200 300 400 500 600 s p ee d µ m /h egf concentration ng/ml after 04 hours after 20 hours fig. 11. radial speed of healing with respect the cell concentration of egf for 4 steps: (a) 12h, (b) 20h, (c) 28h and (d) 36h compared with 4 hours. the tangential component of the velocity described in equation (15b) shown in figure (12) below. fig. 12. tangential speed of healing to the egf concentration for 10 steps of time. figure (13) shows the comparison between the first 4 hours to the 12, 20, 28 and 36 h. 0 1 2 3 4 5 6 0 100 200 300 400 500 600 s p ee d µ m /h egf concentration ng/ml after 04 hours after 12 hours 0 20 40 60 80 0 100 200 300 400 500 s p ee d µ m /h egf concentration ng/ml 04 hours 08 hours 12 hours 16 hours 20 hours 24 hours 28 hours 32 hours 36 hours 40 hours (b) (a) 0 0.5 1 1.5 2 2.5 3 3.5 4 0 100 200 300 400 500 600 s p ee d µ m /h egf concentration ng/ml after 04 hours after 28 hours 0 2 4 6 8 10 12 14 16 18 0 100 200 300 400 500 600 s p ee d µ m /h egf concentration ng/ml after 04 hours after 36 hours (d) (c) nebras h. ghaeb al-khwarizmi engineering journal, vol. 16, no. 4, p.p. 2740 (2020) 36 fig. 13. tangential speed of healing with respect to the cell concentration of egf for 4 steps: (a) 12h, (b) 20h, (c) 28h and (d) 36h compared with 4 hours. 5. discussion figure (6) showed the fluctuation in the cell density amount for the direction from the limbus to the center of the eye, for different time of healing started from 4h postoperatively to 40h. the behaviour here agrees with the wave theory and also satisfy the clinical evidence that the stem cells will kinetically increase the mitotic generation activity, which increases the number of cells ready for migration at the first instant after surgery. this motivated kinetic activity will be decreased exponentially reaching the new cells to the center of the cornea. for each instant of time (4h) a wave started from limbus toward the center with fluctuation period and depression rate different from one to another. figure (7) the cell concentration behaviour started the first 4h with about flat change building up to increase the concentration near the center of the eye within time. after 40h the concentration level will reach the maximum required protection [5, 7, and 11]. it is evident from figure (9) that the increase in the egf concentration level will increase the healing speed. biologically this is often due to an increase in the diffusion of the produced cell. this increase would happen after the wave of healing reaches close to the center of the corneal surface. the predicted speed of healing would alter from 14.690, 32.649, 97.208, 96.658, and 128.150 µm/h for the 4, 12, 20, 28, 36 hours’ time of healing. the average of the ten steps maximum speed of healing is 72.872 µm/h, whereas the average of the means of the ten steps of times is 62.516 µm/h witch agrees with the biological and practical findings [2, 5, 10 and 20]. this leads to a practical sense that the speed of healing or diffusion rate both are compensated with respect to the position and time to recover the effect reepithelization of the surface of the cornea [17, 23, 29, and 30]. 0 2 4 6 8 10 12 0 100 200 300 400 500 600 s p ee d µ m /h egf concentration ng/ml after 04 hours after 12 hours 0 2 4 6 8 10 12 14 0 100 200 300 400 500 600 s p ee d µ m /h egf concentration ng/ml after 04 hours after 20 hours (a) (b) 0 10 20 30 40 50 60 0 100 200 300 400 500 600 s p ee d µ m /h egf concentration ng/ml after 04 hours after 28 hours 0 10 20 30 40 50 60 0 100 200 300 400 500 600 s p ee d µ m /h egf concentration ng/ml after 04 hours after 36 hours (c) (d) nebras h. ghaeb al-khwarizmi engineering journal, vol. 16, no. 4, p.p. 2740 (2020) 37 6. conclusions the overall healing process of epithelial postprk surgery has many biological and chemical effective parameters. these parameters all together affect the cells mitotic and migration, that physically represented by the speed of reepithelization. to understand the mechanism of healing two components of velocity of reepithelization have been estimated and compared with the biological finding. during the 40 hours of the study, the maximum radial velocity reaches about 16.85 µm/h in the healing diameter of 2mm, whereas the maximum tangential velocity was about 55.48 µm/h in the same healing diameter. these two components give a speed of re-epithelization of 58 µm/h which agrees with the biological and practical healing speed of 60 µm/h. furthermore, we need more mathematical manipulation and prediction tools (such as artificial intelligence [47] and safety criteria [48] to check the predicted values) that finally we could estimate the required healing process per each patient after considering the other refractive error values. 7. references [1] j.l. 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[48] n.h. gheab, s.n. saleem, "comparison study of emg using wavelet and neural network," al-khwarizmi eng. j., vol. 4, no. 3, pp 108119, 2008. )2020( 2740، صفحة 4، العدد16دالمجلجلة الخوارزمي الهندسية م نبراس حسين غايب 40 دراسة مكونات السرعة الشعاعية والمماسية لشفاء النسيج الطالئي بعد جراحة اصالح قرنية العين البشرية نبراس حسين غائب جامعة بغداد /كلية الهندسة الخوارزمي/ الطب الحياتي هندسة قسم nebras@kecbu.uobaghdad.edu.iq:البريد االلكتروني الخالصة ) هي احدى تقنيات تصحيح االخطاء االنكسارية والتي تبتدأ بازالة الطبقة الطالئية االماية لقرنية العين prkاستئصال القرنية باالنكسار الضوئي ( ساعة تقريًبا ، تتجديد الطبقة الطالئية االمامية التي إزيلت مسبقا لتعاود حماية العين ٤٨البشرية ثم يستخدم الليزر كعالج تصحيحي. بعد هذا اإلجراء بفترة تكون آلية إعادة نية باتجاه الجزء المركزي منها. والنسيج الطالئي) من طرف القربناء إعادة عملية تسمى والتي (هذه عملية التجديد تدأبتجديد. البشرية من الهجرة) بسرعة في اتجاهين: شعاعي وعرضي.وتسمى ب( هاتركيززيادة االنقسام) وب( ياتغيير في كثافة الخالخالل النسيج من هذا تكوين تجاه االسؤولة عن الطبقات المتداخلة بالموهي الشعاعية ( من المركبةكالل قيمة مركبات السرعة العادة نمو الطبقة الطالئية في هذه الدراسة ، تم تقدير م سرعة إعادة التي تقدر دائًما قي ، على عكس الدراسات السابقةالول مرةالمركز) من االطراف باتجاه ة الشكل يالعرضية (موج الخارجي للقرنية) والمركبة فقط. النمو لمركزي في شكل أظهرت النتائج أن شكل االتجاه لكال المكونين يتفق مع السلوك الحركي لالنقسام والهجرة ، حيث تتقلب كثافة الخلية القصوى نحو الجزء ا ٥٥٫٤٨ميكرومتر / ساعة، بينما كانت السرعة العرضية القصوى ١٦٫٨٥هي ، كانت أقصى سرعة إلعادة البناء ملم ٢االضمحالل األسي. لقطر عالج يبلغ ميكرومتر / ساعة والتي تتوافق مع سرعة الشفاء البيولوجية والعملية التي ٥٨ميكرومتر / ساعة. يعطي هذان المكونان سرعة إعادة تكوين النسيج الطالئي الكلية المطلوبة ووقت الشفاء الكلي للتحكم في فترة لعالقة بين الطبقة الطالئيةساعة. سيؤدي تقدير هذين المكونين إلى فتح الطريق لفهم اميكرومتر / ٦٠تبلغ العالج للمريض بعد الجراحة. <4d6963726f736f667420576f7264202d2038342d393120d5ddc7c120e6e3d5d8ddec20e6dac8cf20c7e1d1cde3e420e6ddd1edc7e1> al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 15, no. 3, sptember, (2019) p. p. 8491 study the effects of machining parameters on surface roughness for free form surface using taguchi method safaa k. ghazi* mustafa m. abdulrazaq** abdulrahman s. sultan*** firyal s. muhi**** *,**,***,**** department of production engineering and metallurgy/ university of technology/ baghdad/ iraq *email: safaa_kadhim1988@yahoo.com **email: mustafaalneame@yahoo.com (received 25 november 2018; accepted 19 february 2019) https://doi.org/10.22153/kej.2019.02.002 abstract the surface finish of the machining part is the mostly important characteristics of products quality and its indispensable customers’ requirement. taguchi robust parameters designs for optimizing for surface finish in turning of 7025 al-alloy using carbide cutting tool has been utilized in this paper. three machining variables namely; the machining speeds (1600, 1900, and 2200) rpm, depth of cut (0.25, 0.50, 0.75) mm and the feed rates (0.12, 0.18, 0.24) mm/min utilized in the experiments. the other variables were considered as constants. the mean surface finish was utilized as a measuring of surface quality. the results clarified that increasing the speeds reduce the surface roughness, while it rises with increasing the depths and feeds. using the analysis of variance, it found that the most effective variable is cutting speed with (53.85%) and the depths has the smallest influence with (20.09%). the data set from the experiments was appointed for implementing the optimum procedure, depending on the principle of taguchi way. the result of calculation with the experimental outcome was in good agreement. keywords: feeds, surface finish, surface roughness, taguchi. 1. introduction machining technologies case includes size components diminishing, enhancement of the surface quality, tightest tolerance and manufacture accuracies, reduce cost, reduce size of batches and diminished weight etc. [1]. the surface finish of the machining part is one of the mostly important part quality characteristic. the actual profile of surface is the superposition of errors for the form, roughness and waviness. the deviation is define in international standard. the surface finish greatly effects on the functional performance of mechanical part like as fatigue strength, wear resistance, holding a lubricant and ability of distributing, transmission and heat generation, resistance of corrosion etc [2,3]. the average surface roughness (ra) was select as characteristics of surface roughness in operation of turning, which is the mostly utilized standard variable of surfaces finish. in cutting processes, we have two sharps and sometimes contrary requirement. the first one with high qualities surface while the second one with high productions rates. however, more than one theoretical model involved approximations and simplification in relations with reality machining processes and doesn’t take in to accounts any imperfection in chips formation and surfaces finish. consequently, the solution of the analytical in general wasn’t accurate enough to utilize practically [4]. these mathematical (statistical) ways and approaches integrated experimentally, thus it provides sufficient calculations of precision of the reality condition in which the machining operation happen. this work demonstrates the applications of the taguchi technique to identify safaa k. ghazi al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 8491 (2019) 85 the optimum turning variables for surfaces finish in dry machining of al-alloy. 2. theoretical considerations this work introduces a mathematical representation for the curves mathematical which include parametric representations, in addition to propose the derivation of the curve. an adopting way for generating the tool paths have been implemented depending on cam program package. the equations of parametric curves describe the dependable and undependable variable in term of parameters. the equations can convert to nonparametric forms by eliminate the dependable and undependable variable from the equations. an equation of the parametric for freeform surface is constructed by two variables (u), and the vector of parametric functions representing the coordinate's position of the curve [5]. p (u) = [x (u), y (u), z (u)] u from [1, 0] … (1) in this paper bezier technique illustrated for representing the proposed study curve. using the fifth order degree with six control points to each single curve to represent the profile curve of the product, and the equation of the proposed bezier curve is ]1[)( 2345 uuuuuup =                     − − −− −− −−− 000001 000055 000102010 0010303010 052030205 15101051                     6 5 4 3 2 1 p p p p p p … (2) 2.1 theory of taguchi method the method concept is based on that the manufacturing quality should be measure by the amount of deviation from the required values [6,7]. taguchi technique is used a statistical measuring of performances call signal to noise ratio taken from control theory to analyzing the result [8]. in this way, the term ‘signal’ refers to the desirable values of mean for the outputs characteristics and the term ‘noise’ refers to the standard deviation. in this paper will be using l9. s/n=-10 log[1/n∑ ( � �� )� � � ] i=1, 2, …..n … (3) where n are the measurements of input yi refers to the measurements value of output. the input parameter of nine simple are design with using minitab16 program. 3. implementation the work the equipment of the implementations which utilized in the work is dividing in two parts: 3.1 software requirement the creation of cad/cam modeling has been implemented using designing programs package for the purpose of constructing and reconstructing the surface, transferring the cad data, beside to generating the tool paths and postprocessing that required to implement the machining process. these operations illustrated using matlab and ug-nx9 program. matlab software is allowing matrix manipulation, implementation of algorithms and plot function. curve have been modeled using bezier depends on the algorithm includes the control point matrices. ug-nx is a program and advanced cad/cam developing, it is provides integrated design management of parametric model and machining as shown in fig. 1. safaa k. ghazi al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 8491 (2019) 86 (a) (b) fig. 1. implementing the cad model: (a) bezier curves using matlab, (b) achieving the model using ug-nx software. 3.2 hardware requirements the hardware equipment that used in this work consists of the computer and cnc turning machine. 3.2.1 cnc turning the turning process carried out in this work on cjk6132 standard turning machine model 2000 ce tuv has been utilized that illustrated in fig. 2. the machine specification is shown in table 1. the machine is located at university of technology/ workshop and training center. fig. 2. c-tek turning (cnc machine). table 1, specifications of c-tek cnc turning machine bed over swing 320mm φ peed(variable)s of range r/min )2500~100( travel xisa-x max mm )160( travel xisa-z max mm )500( rsetrave rapid x m/min )5( rsetrave rapid z 10m/min unit input min 0.001mm 3.2.2 cutting tools cemented carbides have high hardness over a high thermal conductivity, wide range of temperatures, high young's modulus making them die materials and effective tool for a range of applications [9]. it is suitable for machining at higher speeds than those which can be used for tungsten carbide. typical cutting speeds are: 30 to 150 (m/min). carbide cutting tool was used in this work as shown in fig. 3. fig. 3. carbide cutting tools. 3.2.3 tester of surface roughness pocket surf is instrument that utilized for measuring the parts surface roughness after the turning illustrated in fig. 4. it’s a reliable surfaces roughness gauge and an economical priced device. the specification of the instrument is shown in table 2. safaa k. ghazi al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 8491 (2019) 87 fig. 4. tester of pocket surf. table 2, specifications of the surface roughness tester measuring ranges: ra (0.03) (6.35) μm. ry (0.2) (25.3) μm. rz (0.2) to (25.3) μm. weight: 435 g. totally dimension 140 x 76 x 25 mm. display resolution 0.01 μm 3.2.4 material of the workpiece 7025 aluminum alloy is selected to be machining with chemically compositions of the samples illustrated in table 3. table 3, the chemical compositions for aluminum 7025. si% mn% cu% mg% pb% cr% ni% 0.16 0.216 2.14 1.55 0.07 0.090 0.012 zn% ti% ga% v% fe% other% al% 4.93 0.038 0.01 0.007 0.42 0.132 90.21 this alloy have cut to nine parts. each specimen has a dimension of (diameter 30 and height 120) mm as shown in fig. 5. fig. 5. work piece dimension. 3.3 tool path generation and simulations the process that follows designing and representing the cad models is tool paths generation utilizing ug-nx9 program. using different values of cutting condition (speed, depth of cut and feed) as shown in table 4 and makes the simulations for the entire process beside to obtaining the g-code of the program that created in the paper using ug-nx9 package is shown in fig. 6. fig. 6. generating the tool paths and simulation using ug-nx9. table 4, parameters level cutting speed (rpm) 1600 1900 2200 depth of cut (mm) 0.25 0.50 0.75 feed rate(mm/min) 0.12 0.18 0.24 the three machining variables that implemented on the experimental work for the (9) work pieces i.e. speeds, depths of cut and feeds clarified with table 4. the resultant shape of the samples after implementing is illustrated in fig. 7. fig. 7. final sample shape of turning. different conditions for each experiment producing the samples, depending on these conditions a various values of surface roughness have obtained. fig. 8. clarify the measurement of surface roughness using the pocket surf probe. 120 mm d120 safaa k. ghazi al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 8491 (2019) 88 fig. 8. measuring the surface roughness 4. results and discussion this section demonstrates and discuses the results values of the surface roughness is depend on the threelevel parameters depth of cut, speed of cutting and feed rate. analyzing the output result carried out utilizing variance analysis method for finding the optimal machining factors with the aid of minitab software. after implementation the experimental part on the 9 parts with three parameters are shown in table 5. table 5, reading of surface roughness and s/n ratio 4.1 effect of cutting speeds, depths of cut and feed rates on surface roughness fig. 9 to 11 clarifies the effects of depths of cut, cutting speeds, and feed rates on the resultant surface roughness. it is noting that increasing the cutting speed decreases the surface roughness; this mens that the high cutting speed improving the surface roughness. while the rise in the feed rates and depths of cut led to increase in surface roughness, the cutting speeds influence on the friction which is decreased with increasing the cutting speeds. fig. 9. cutting speed and feed rate effect on surface roughness. no. cutting speed (rpm) depth of cut (mm) feed rate (mm/min) ra1 ra2 average of ra s/n ratio 1 1600 0.25 0.12 0.93 1.13 1.030 -3.424 2 1600 0.50 0.18 1.30 1.21 1.255 -0.965 3 1600 0.75 0.24 1.12 2.10 1.610 -4.521 4 1900 0.25 0.18 0.91 0.87 0.890 1.707 5 1900 0.50 0.24 1.36 0.99 1.175 1.462 6 1900 0.75 0.12 0.89 0.95 0.920 2.908 7 2200 0.25 0.24 0.87 0.69 0.780 3.285 8 2200 0.50 0.12 0.66 0.74 0.700 6.131 9 2200 0.75 0.18 1.11 0.96 1.035 4.506 safaa k. ghazi al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 8491 (2019) 89 fig. 10. cutting speed and depth of cut effect on surface roughness. fig. 11. effect of depth of cut and feed rate on surface roughness. 4.2 variance analysis (anova) analyzing the result of experiments have been implemented using variance analysis method (anova) for finding the influence of turning variables on surface finish that depend on cutting variables depths of cut, speeds and feed rates. the results of the analysis of variance for surface finish are shown in table 6. table 6, variance analysis of the proposed parameters. source of variance degree sum of squares f ratio p (%) cutting speed(rpm) 2 0.3282 3.50 53.85 depth of cut(mm) 2 0.1247 0.77 20.46 feed rate (mm/min) 2 0.1407 0.90 23.09 error ,e 2 0.0158 2.75 total 8 0.6094 100 the f ratio value of 3.5 for the cutting speed is greater than the other variables shown in table (5). consequently, the most effective variable is the cutting speed with (53.85%) which is about twice of the feed rate of (23.09%), while the depth of cut has a small effect with (20.46%). the contribution percent are given in fig. 12, clarifying the most effective variables of the entire process among the conditions of machining which is cutting speed (rpm). fig. 12. influential effects based on percentage of distributions. 4.3 optimal condition the main effect plot is utilized to find out the optimum condition of design to give the optimal surface roughness through select the best regions by use of minitab software. fig. 13 shows the main effects plots of the surface finish. that plot shows the variations of response (3) variables individually, such, depths of cut, cutting speeds and feed rates separately. the result are showing the optimum condition for surface finish which is: cutting speed at level-3 (2200 rpm) depth of cut at level-1(0.٥٠ mm) and feed rate at level-1(0.12). safaa k. ghazi al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 8491 (2019) 90 fig. 13. main effect plots for surface roughness. 5. conclusion from this work, the following conclusions were drawn: 1. the experimental results show the main effects of process parameters on surface roughness for 7024 al-alloy. the surface roughness decreases with the increasing in cutting speed. 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[9] jose m. tarragóab, selassie d. joan esteved and luis llanes “influence of the microstructure on the thermal shock behavior of cemented carbides” ceramics international journal, vol 42, issue 11, pp. 12701-12708, 2013. )2019( 8491، صفحة 3، العدد15دجلة الخوارزمي الهندسية المجلم صفاء كاظم غازي 91 دراسة تأثير متغيرات التشغيل على الخشونة السطحية للسطوح الحرة باستخدام طريقة تاكوشي ***سلطان الرحمن شاكر عبد **مصطفى محمد عبد الرزاق *صفاء كاظم غازي ****فريال صباح محي العراق / الجامعة التكنولوجية/ االنتاج والمعادنقسم هندسة *،**،***،**** yahoo.com1988safaa_kadhim@: البريد االلكتروني* mustafaalneame@yahoo.comالبريد االلكتروني: ** الخالصة م االنهاء السطحي لألجزاء المشغلة يعد من اهم الخواص لجودة المنتجات المصنعة واالكثر تطلبا للمستهلك. تم استخدام طريقة تاكوشي لتصميان لتي تم بواسطة عدد قطع كاربيدية وا ٧٠٢٤التجارب للحصول على افضل خشونة سطحية في عملية الخراطة باستخدام المكائن المبرمجة لسبيكة المنيوم نوع ) ملم و معدل ٠٫٧٥ ،٠٫٥٠ ،٠٫٢٥دقيقة، عمق القطع ( ) دورة/٢٢٠٠ ،١٩٠٠ ،١٦٠٠استخدامها لهذا البحث. ثالثة متغيرات للتشغيل وهي: سرعة القطع ( اخذ معدل االنهاء السطحي ) ملم/دقيقة تم استخدامها للتجارب العملية. فيما تم تثبيت باقي المتغيرات التشغيلية االخرى. تم ٠٫٢٤، ٠٫١٨، ٠٫١٢التغذية ( بينما تزداد الخشونة بزيادة كل من عمق القطع ومعدل ،كمؤشر لجودة السطح. اظهرت النتائج ان زيادة سرعة القطع تعمل على تقليل الخشونة السطحية ) بينما عمق القطع هو االقل تأثير %٥٣٬٨٥التغذية. تم استخدام تقنية تحليل تباين العناصر(انوفا) وجد ان اكثر المتغيرات تأثيرا هو سرعة القطع بنسبة ( مقبولية حيث اظهرت النتائج ،خشونة سطحية باالعتماد على طريقة تاكوشيمن خالل التجارب تم تحديد افضل ظروف لتحديد افضل ،)%٢٠٬٠٩بنسبة ( للعملية. جيدة al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 4, no. 3, pp 1833 (2008) new adaptive data transmission scheme over hf radio khalifa abboud salim*, abdul-karim a.r. kadhim** and adil h. ahmad*** *departement of information and communication/ al-khawarizmi college of engineering/university of baghdad ** departement of information/ collage of engineering/ al-nahrain university ***department of electrical and electronic engineering/ university of technology (received 6 march 2008; accepted 2 september 2008) abstract acceptable bit error rate can be maintained by adapting some of the design parameters such as modulation, symbol rate, constellation size, and transmit power according to the channel state. an estimate of hf propagation effects can be used to design an adaptive data transmission system over hf link. the proposed system combines the well known automatic link establishment (ale) together with variable rate transmission system. the standard ale is modified to suite the required goal of selecting the best carrier frequency (channel) for a given transmission. this is based on measuring sinad (signal plus noise plus distortion to noise plus distortion), rsl (received signal level), multipath phase distortion and ber (bit error rate) for each channel in the frequency list. channel condition evaluation is done by two arrangements. in the first an fft analysis is used where a pilot signal is transmitted over the channel, while the data itself is used in the second arrangement. passive channel assessment is used to avoid bad channels hence limiting the frequency pool size to be used in the point to point communication and the time required for scanning and linking. an exchange of channel information between the transmitting and receiving stations is considered to select the modulation scheme for transmission. mainly mpsk and mfsk are considered with different levels giving different data rate according to the channel condition. the results of the computer simulation have shown that when transmitting at a fixed channel symbol rate of 1200 symbol/sec, the information rate ranges from 2400 bps using 4fsk up to 3600 bps using 8psk for snr ranges from 11db up to 26db. keywords: ale, adaptive modulation. introduction propagation effects in hf sky-wave channels impose many restrictions on this communication media. these restrictions can be grouped into the effects of background noise, interference, and multipath propagation. hf band has been of great interest for beyond line of sight long distance military communications. hf radio is the central element particularly for countries which can’t count on reliable access to satellite links in wartime. in addition to its price advantage and freedom from third party it’s inherent resilience to counter measure, and independence from foreign ownership and controlled communications assets which make it attractive for command, control, computer and communication, interchange (c 4 i) system military users. unfortunately hf communication is complicated by severe interference from other users of the hf band, impulsive atmospheric noise, limited bandwidth, multipath propagation, which yields frequency selective fading. the increase in the use of the internet protocol (ip) networks in the military applications [1] has led to the necessity of integration of various transmission media (hf, vhf, uhf, microwave, fiber optic) into one heterogeneous network. integration of hf link as part of any network represent a bottleneck to the whole network. to insure reliable and efficient communication over such networks a major part of research activities has been directed toward achieving reliable high khalifa abboud salim al-khwarizmi engineering journal, vol. 4, no. 3, pp 18-33 (2008) 19 data rate communication in the presence of severe interference and time varying channel conditions. various techniques are used to combat hf channel impairments such as diversity reception which is commonly used at hf installations, hence improves the reliability of hf channel [2]. the basis of diversity reception is to take advantage of signals that are not correlated, and combines these signals from separate receivers. there are several forms of diversity reception, all of which require additional equipments. besides to diversity reception, spread spectrum, power control and adaptive modulation are also used. the approach being undertaken in this work is to optimize the performance of hf radio communication over time varying channels, examine the quality and propagation characteristics of a radio channel, and measure the relevant hf channel parameters. acceptable ber can be maintained by adapting some of the design parameters such as modulation, symbol rate, constellation size besides to the automatic selection of the best frequency from a set of preassigned channels to the time varying channel environment [3]. besides to channel state such as fading, noise and interference power characteristics, throughput of any wireless communication channel is affected by different communication parameters such as symbol rate, transmit power and coding rate. adaptive modulation has been proposed as an efficient technique for improving the spectral efficiency over fading channels. adaptive modulation has been extensively studied in [3, 4]. with adaptive modulation optimum symbol rate at a given bit error rate ber is achieved where a high spectral efficiency is maintained. in this work an estimate of the channel state is done at the receiver side and the channel information are fed back through an error free feedback channel. the channel state is used to determine the best carrier frequency from a frequency pool and the appropriate constellation size. therefore an optimal two step adaptive hf system is considered. the channel state is obtained through a pilot single tone unmodulated carrier transmitted through the channel, at the receiver side sinad plus multipath phase distortion and rsl which reflects channel quality are measured and fed back to the transmitter. the snr threshold is used for both ale and choosing appropriate modulation and hence constellation size according to threshold bit error rate (berth), which is previously evaluated based on the simulation results. the modulation type and hence constellation size are restricted to mfsk and mpsk, for the reason of constant amplitude signaling, while mqam is avoided because it uses different amplitude levels which will be affected by fading phenomenon of the channel. iisystem model a communication link which consists of a transmitter, a receiver, hf channel and feedback channel as shown in fig.(1) was considered. for each transmission the carrier frequency and the modulation scheme are selected based on the estimated snr, because the spectral efficiency is adjusted to achieve optimum performance for a specified threshold ber. the receiver is assumed to detect all the erroneous bits. the hf channel can be seen as consisting of two components. firstly a filter h(f,t) which varies over both frequency and time representing the changing conditions caused by multipath propagation and different kinds of ionspheric phenomena, secondly the noise n(t) and the interference i(t) from other hf users . the feedback channel is used to convey the link quality analysis lqa information, in order to use these data for the configuration of the transmitter station. since there is no need to use high data rate in the feedback channel then the channel can be well protected using error correcting coding and maximum transmit power. lqa is used to provide the transmitter with the necessary information about the measured snr, rsl and multipath phase distortion. khalifa abboud salim al-khwarizmi engineering journal, vol. 4, no. 3, pp 18-33 (2008) 20 hf channel n(t), i(t) data in data out fig. 1. block diagram of hf radio link. . 1-the communication channel in this investigation the widely used and well known itu-r approved watterson gaussian scatter model known as watterson model is used in the simulation of the hf channel [5,6]. this model considered stationary for small bandwidth up to 3khz and short time less than 10 minutes. three standard simulation channels termed good, moderate, and poor presented in table (1) are used. the hf channel was modeled as a tapped delay line with one tap for each propagation path as shown in fig.(2). the delayed input signal at various stages of the delay line is multiplied by the random process gi(t) and hence modulated in both amplitude and phase. table 1 ccir test channel parameters. condition good moderate poor delay spread (ms) 0.5 1 2 frequency spread 0.1 0.5 1 input g1(t) g2(t) g3(t) gi(t) awgn output fig. 2. watterson hf channel model. 2adaptive modulation a basic relation in wireless digital communication is that a certain transmission bit rate can be achieved at a certain bit error probability for a specified snr. for non adaptive digital communication system, the modulation type and error correcting codes are chosen such that acceptable bit error rate is achieved. when the coding fails to compensate for occurred errors the link layer will ensure that the data is correctly received by requesting a retransmission of the erroneous databy means of automatic repeat request arq. as the snr varies a more stable performance can be accomplished using adaptive modulation in such a way, the transmitter and receiver are adapted to the changing channel quality by aiming at the target bit error rate. however the ber at the receiver would be a good metric to decide switching between different modulations but reliable ber estimation is difficult over short h(f,t) transmitter receiver lqa d d d khalifa abboud salim al-khwarizmi engineering journal, vol. 4, no. 3, pp 18-33 (2008) 21 periods, thus channel snr was used for switching between different modulation types. the channel snr is defined for each modulation type such that it guaranties a ber below a certain threshold berth. adaptive modulation is proposed as an effective measure to maximize the spectral efficiency of the time variant wireless channel [7]. choice of modulation type and setting of modulation switching level are the most important factors that affect the performance of adaptive modulation system. setting of modulation switching levels is done using the target ber (berth) criterion. the symbol error rate ser and hence ber for different modulation types are as follows [8]. … (1) where q(x) is the q-function and γ = es/no the equivelant ber for qpsk is: ...(2) the ser for coherent mfsk is given by: …(3) the probability density function pdf of the fluctuations in instantaneous received power x, in a rayliegh channel are given by ...(4) where x is the average signal power. for any modulation scheme if pg(snr) is the gaussian ber performance then the upper bound for the ber performance in a rayliegh channel is [7]: ...(5) therefore the upper bound ber performance of an adaptive modulated signal may be computed from: …(6) where l1….l4 are the snr switching thresholds. the throughput of the adaptive modulation system can be expressed as: …(7) 3 automatic link establishment (ale) ale was developed to automatically select a frequency for automatic linking in point to point or network based communication. clearly the availability of different modems with a robust waveforms has an impact on frequency selection and link establishment process. however hf communications are subject to disturbances and irregularities in the ionosphere, fairly high rate communications may be supported at some times. all the prediction programs give the long term median values of maximum usable frequency (muf) and lowest usable frequency (luf). the final selection of the appropriate frequency is upon the operator taking into account the availability of clear or interference free channel. the selection of the best frequency is done by using long term prediction. the use of rtce techniques at the receiving station can provide a measure of channel conditions to be used for ale functions [10]. in addition to the channel state information from propagation prediction and channel sounding, ale is used to maintain linking with remote station. iii hf system adaptation algorithm the proposed hf adaptation process is attempted at startup of the system in two steps: step 1: at startup of the communication, both the transmitter and the receiver generate a lqa table through the sounding process. ale performs linking process by choosing the best channel for communication based on the lqa data of the rank ordered channels. the selected communication frequency is chosen to be very close to the linking frequency in order to have the same propagation conditions. step 2: the second phase is the rate adaptation process, which is performed during the communication process. initial handy rate with certain modulation technique is chosen depending on the snr of the selected channel. during the communication process the system attempts to test the ber for higher possible bit rate. if the receiver acknowledges the reception of the test data with acceptable ber (chosen to be ≤ 10 -3 ), the transmitter changes its rate to the new higher rate. fig.(3) gives the adaptation algorithm of a point to point communication system. khalifa abboud salim al-khwarizmi engineering journal, vol. 4, no. 3, pp 18-33 (2008) 22 time transmitter receiver phase1 1listen for co-channel scanning ( synchronous existence, or asynchronous) 2 channel selection tune and send ale word (wait for reply twr ,if no check valid address, tune reply then try another up, send response channel) wait for ack 3check for valid response receive ack enter link send ack, enter linking state state. 30 sec activity timer is started twa phase 2 4 start communication at bi-directional pre-determined rate data transmission according to snr 5test for higher transmission test for acceptable received rate (known sequence) nack ber (send ack ) wait for ack 6return back to original rate fig. 3. adaptation algorithm for point to point. khalifa abboud salim al-khwarizmi engineering journal, vol. 4, no. 3, pp 18-33 (2008) 23 ivadaptive hf system simulation matching the data rate to the channel condition can be achieved in two steps, first step is selecting the best channel frequency to carry traffic data through ale, and choose the best modulation which provides highest possible bitrate with acceptable ber. 1ale simulation ale initiates calls on pre-assigned rank ordered channels, depending on the lqa memory data. the lqa information exchanged between all the stations is used to optimize the choice of channels. the sequence of channels to be used in linking is derived from the information content of lqa parameters. the best channel score is tried first. the feedback channel is assumed to be error free with high transmit power and robust error correcting code to insure the correct reception of the acknowledged data. three types of information [10], bit error rate, signal plus noise plus distortion to noise plus distortion sinad, measure of multi-path mp (optional), are required to assess specific channel order. lqa data are used to score the channels and to support selection of the best channel for linking and communication. aber measurement for each channel to be tested for ber, a stream of binary data is transmitted over the channel. the bit error rate is calculated at the receiver as follows. ...(8) bsinad measurement under the assumption that the noise is a stationary or a slowly varying process, and that the noise spectrum does not change significantly in between the update period of lqa, the effect of additive noise on the magnitude spectrum of a signal is to increase the mean and the variance of the spectrum. the noisy signal model in the time domain is given by …(9) where x[m], n[m] and y[m] are the signal, the additive noise and the noisy signal respectively, and m is the discrete time index. the frequency domain of the noisy signal model of eq. (9) is: ...(10) where y(f), x(f) and n(f) are the fourier transform of the noisy signal y[m], the original signal x[m] and the noise n[m] respectively, and f is the frequency variable. the noisy signal at the receiver front end is buffered and divided into segments of n samples length. each segment is transformed via fast fourier transform fft to n spectral samples. the time averaged power spectrum of the noisy signal is obtained from the whole period ...(11) where │yi(f)│ is the spectrum of the i th noisy signal frame, and it is assumed that there are m frames in the allocated period. ...(12) in this work the channel is tested for sinad, using a generic frequency domain fft. a single tone is transmitted, the received signal is analyzed to determine the sinad. obviously the reference pilot tone is known to the receiver then the subtraction of the power content of the pilot tone from the total averaged received power yields the noise plus distortion power added over the channel. then the received sinad can be expressed as follows: …(13) the averaging of the above measured parameters is taken over 5 seconds. this time is arbitrary chosen to be long enough to accommodate slow and fast variations of the channel environment and allows accurate signal strength and phase measurements. fig.(4) shows a 500 hz single tone passed through a 3-skywave hf channel with snr of 10 db. khalifa abboud salim al-khwarizmi engineering journal, vol. 4, no. 3, pp 18-33 (2008) 24 fig. 4. single tone through hf channel. creceived signal level and multipath distortion besides to sinad measurement, rsl, and multi-path phase distortion can be measured using n point fft. then the rsl of the k th bin signal is measured and averaged over the whole period: ...(14) in the same manner phase distortion can be computed from the fft, by subtracting the phase of the reference pilot tone from the phase of the analyzed received signal. ...(15) where y(k) and x(k) represent the k th amplitude component of the received and transmitted signal respectively. 2 modulator performance test the performance of different types of modulation techniques was determined by calculating bit error rate for different channel parameters and signal to noise ratio. the performance test have been carried out using different modulation techniques bpsk, qpsk, 8psk, fsk, 4fsk, 8fsk (the effect of carrier synchronization on the overall performance was not considered and the system is considered synchronized). figs.(5) and (6) represent the theoretical performance of the different modulation techniques over awgn channel. figs.(7-14) represent the ber performance of the same modulation types over different channel conditions. it is clearly shown that mfsk modulation scheme acheives the same bit error rate at low signal to noise ratio when compared with mpsk. so with power limited systems mfsk is preferable while at bandwidth limited systems mpsk is preferable. mpsk modulation is bandwidth efficient scheme so as m increases in value the bandwidth efficiency also increases at the expense of increased eb/no. the proposed system uses mfsk at low eb/no unless the required bandwidth exceeds the limited 3 khz bandwidth while at higher eb/no the bandwith efficient mpsk will be employed. 3rate adaptation scheme the second phase of adaptivity is to choose the highest transmission rate with appropriate modulation technique which gives ber performance of less than 10 -3 at the specified snr. after linking takes place the transmitter establishes communication with the distant station using handy initial transmission rate. this rate is a predetermined rate chosen based upon the snr from the lqa table. during the linking process the basic ale word is used to estimate the present khalifa abboud salim al-khwarizmi engineering journal, vol. 4, no. 3, pp 18-33 (2008) 25 ber. to test the validity of the channel, a stream of known data is transmitted along the link with a rate higher than the initial selected data rate. if the receiver acknowledges the reception of the data with acceptable ber, then the transmitter attempts transmission at higher rate and so on according to the adaptation algorithm. if negative acknowledgment is received, then the transmitter returns to the initial data rate. when transmission is carried out at fixed channel symbol rate of 1200 symbol/sec the required bandwidth and signal to noise ratio for both mpsk and mfsk modulation signals simulated over good channel to obtain ber=10 -3 are shown in tables2& 3. however the hf channel is bandwidth limited to less than 3 khz in military applications, then it is clear that at low snr, power efficient modulation techniques (mfsk) must be employed. while at high snr the bandwidth efficient modulation techniques (mpsk) will be employed. a signal to noise ratio threshold is chosen such that a best utilization of bandwidth with minimum signal to noise ratio is achieved. table 4 shows the signal to noise ratio boundaries for best utilization of bandwidth with minimum signal to noise ratio. the data rate throughput evaluated over the specified threshold is plotted in fig. (15). table 2 bandwidth and power efficiency of mpsk for ber=10 -3 m m rs symbols/sec rb bps minimum bandwidth (hz) ηb bit/s/hz eb/n0 (db) for ber=10-3 good moderate poor 2 1 1200 1200 2400 0.5 13 13.75 15 4 2 1200 2400 2400 1 13 14.1 15 8 3 1200 3600 2400 1.5 26 35.8 45 16 4 1200 4800 2400 2 not simulated table 3 bandwidth and power efficiency of mfsk for ber=10 -3 m m rs symbols/sec rb bps minimum bandwidth (hz) ηb bit/s/hz eb/n0 (db) for ber=10-3 good moderate poor 2 1 1200 1200 1200 1 14 15 18.2 4 2 1200 2400 2400 1 11 11.8 12.5 8 3 1200 3600 4800 .75 requires high bw 16 4 1200 4800 9600 0.5 not simulated table 4 modulation type selection for ber=10 -3 eb/no (db) modulation type bandwidth efficiency rb (bps) 11≤ eb/no <13 4fsk 1 2400 13≤ eb/no <26 qpsk 1 2400 26≤ eb/no 8psk 1.5 3600 khalifa abboud salim al-khwarizmi engineering journal, vol. 4, no. 3, pp 18-33 (2008) 26 fig. 5. mfsk theoretical performance. fig. 6. mpsk theoretical performance. khalifa abboud salim al-khwarizmi engineering journal, vol. 4, no. 3, pp 18-33 (2008) 27 fig. 7. mfsk performance over awgn channel (simulated). fig. 8. mpsk performance over awgn channel (simulated). khalifa abboud salim al-khwarizmi engineering journal, vol. 4, no. 3, pp 18-33 (2008) 28 fig. 9. mpsk performance over good channel. fig. 10. mpsk performance over moderate channel. khalifa abboud salim al-khwarizmi engineering journal, vol. 4, no. 3, pp 18-33 (2008) 29 fig. 11. mpsk performance over poor channel. fig. 12. mfsk performance over good channel. khalifa abboud salim al-khwarizmi engineering journal, vol. 4, no. 3, pp 18-33 (2008) 30 fig. 13. mfsk performance over moderate channel. fig. 14. mfsk performance over poor channel. khalifa abboud salim al-khwarizmi engineering journal, vol. 4, no. 3, pp 18-33 (2008) 31 fig. 15. hf channel performance. vconclusions combination of a modified ale with a proposed adaptive rate algorithm in which an initial data rate is selected based on the lqa data. this means that sounding channel to be used for both ale and rate selection. the basic ale word is used to estimate the present ber which is then used later to control the transmission rate. the proposed system reduces the time period required to update the lqa data as compared to original time required for the standard lqa. this is because sounding individual channels is carried at predetermined intervals and updated for the selected channel at each transmission using the majority vote criterion. the use of pilot tone to determine the received sinad, rsl, and phase distortion is introduced using fft measurement. this method is simple to implement and true real time operation is obtained with existing digital signal processing chips such as tms320c5x. references [1] d. j. brown, s. e. trinder and a.f. gillespie “an analysis of hf for ip sub-network” 8 th international conference on hf radio systems and techniques, july 2000, uk. [2] r.l. freeman “radio system design for telecommunications” john wiley & sons inc. 2 nd edition 1997, usa. [3] k. a. salim “adaptive hf system for high speed data transmission” ph.d thesis, alrasheed college of engineering and science, university of technology iraq, 2005. [4] a.goldsmith and s.chua “variable rate variable power mqam for fading channels” ieee transactions on communications, oct. 1997. [5] m. rostami, j. angeja, j. tavares and a. navarro “hf channel modeling for real time packet transmission“ ieee milcom 03 conference proceeding, 2003. [6] f. mcverry “high speed data transmission over hf radio links” ph.d thesis, loughborough university of technology, 1984, uk. [7] j. m. torrance and l. hanzo, “upper bound performance of adaptive modulation in a slow rayleigh fading channel”, ieee electronics letters, volume 32, april 1996. khalifa abboud salim al-khwarizmi engineering journal, vol. 4, no. 3, pp 18-33 (2008) 32 [8] s.haykin “communication systems”, john wiley & sons inc. 3 th edition 1994, usa. [9] m. d. street and m. darnell “results of new automatic link establishment and maintenance techniques for hf radio systems”, ieee milcom97 proceeding vol.2 p1067-1071. [10] mil-std-188-141b department of defense standard “interoperability and performance standards for medium and high frequency radio systems”, department of defense, march 1999, usa. khalifa abboud salim al-khwarizmi engineering journal, vol. 4, no. 3, pp 18-33 (2008) 33 طريقت جذيذة لالتصاالث المتكيفت على قناة عاليت التردد *** عادل حميذ أحمذ** عبذ الكريم عبذ الرحمن كاظم*خليفت عبود سالم خايؼح تغذاد / كهٛح ُْذسح انخٕاسصيٙ/ قسى ُْذسح انًؼهٕياخ ٔاالذصاالخ* خايؼح انُٓشٍٚ / كهٛح انُٓذسح/ قسى ُْذسح انًؼهٕياخ** اندايؼح انركُٕنٕخٛح / قسى ُْذسح انكٓشتاء ٔاالنكرشَٔٛك*** الخالصت ٚضغ قٕٛدا ػذٚذج ػهٗ أسرخذاو hfاٌ انرأثٛشاخ انكثٛشج ٔانًرغٛشج يغ انضيٍ ػهٗ اَرشاس انًٕخاخ انالسهكٛح ضًٍ قُاج انرشدداخ انؼانٛح . يثم ْزا انٕسط ألغشاض أألذصاالخ اٌ انًُظٕيح انًقرشحح فٙ ْزا أنثحث ذدًغ تٍٛ .ٚٓذف انثحث انٗ ذطٕٚشيُظٕيح يقرشحح نألذصاالخ انًركٛفح ػثش قُاج انرشدداخ انؼانٛح يغ ذقُٛح , ذحقٛق األذصال انطٕػٙ ٔانز٘ ٚؼُٗ تأخرٛاس انرشدد انًُاسة يٍ تٍٛ يدًٕػح يٍ انرشدداخ انًخصصح يسثقا نألذصال, ذقُٛرٍٛ ًْا ػهٗ حذِ ٔتانرانٙ اخرثاس يذٖ (ذشدد)اٌ اخرٛاس أ٘ يٍ انرشدداخ انًخصصح ٚرى يٍ خالل ذقٛٛى كم قُاج .اخرٛاس سشػح اسسال انثٛاَاخ انًركٛفح . صالحٛرٓا ٔيالءيرٓا نرأيٍٛ األذصال ٔقٛاط شذج األشاسج انًسرهًح ٔيسرٕٖ األشاسج انٗ انضٕضاء تأالضافح انٗ , اٌ اخرثاس كم قُاج ٚرى يٍ خالل ذٕنٛذ َغًح فٙ خٓح األسسال يٍ خالل أسسال سسانح ber كًا ٚرى حساب يؼذل انخطأfftحٛث ٚرى ذحهٛم أألشاسج انًسرهًح تأسرخذاو ,انرشّٕٚ انحاصم فٙ انطٕس اٌ انًؼهٕياخ انُاذدح يٍ ذحهٛم األشاساخ انًسرهًح ٚرى اػادذٓا ػكسٛا انٗ انًشسم ٔتانرانٙ اسرخذايٓا فٙ .يؼهٕيح ٔيقاسَرٓا فٙ خٓح األسرالو . اخرٛاس َظاو انرحًٛم انًُاسة wattersonحٛث ذى ذًثٛم انقُاج ػانٛح انرشدد تأسرخذاو ًَٕرج , ذى اخشاء فحص يحاكاخ تانحاسٕب نرحهٛم ٔأخرثاس أداء ْزِ انًُظٕيح نقذاظٓشخ َرائح األخرثاساخ تأَّ ػُذ ذثثٛد سشػح اسسال انثٛاَاخ . mpsk, mfskٔأسرخذاو َٕػٍٛ يٍ انرضًٍٛ يرؼذد انًسرٕٚاخ ػُذيا ذكٌٕ يسرٕٖ أألشاسج انٗ انضٕضاء قهٛهح ٚؼطٙ سشػح اسسال تٛاَاخ 4fskثاَٛح فأٌ اسرخذاو / سيض1200انخاسخح ػهٗ سشػح نهحصٕل ػهٗ سشػح أسسال تٛاَاخ qpsk, 8pskػُذ اسذفاع يسرٕٖ األشاسج انٗ انضٕضاء ٚرى االَرقال انٗ . ثاَٛح/ تد2400تًقذاس . ػهٗ انرٕان3600ٗ ٔ 2400 <4d6963726f736f667420576f7264202d20ddc7d8e3c920dfc7d9e320e6d3e1ede320e3cde3cf3130302d313037> al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 15, no. 2, june , (2019) p.p. 100107 treatment of waste extract lubricating oil by catalytic cracking process to produce light fractions fatimah kadhim idan* saleem mohammed obyed** *,**department of chemical engineering / collage of engineering / al-nahrain university *email:shemeriya93@gmail.com **email:saleem_mo71@yahoo.com (received 22 october 2018; accepted 10 january 2019) https://doi.org/10.22153/kej.2019.01.003 abstract the catalytic cracking of three feeds of extract lubricating oil, that produced as a by-product from the process of furfural extraction of lubricating oil base stock in al-dura refinery at different operating condition, were carried out at a fixed bed laboratory reactor. the initial boiling point for these feeds was 140 ºc for sample (1), 86 ºc for sample (2) and 80 ºc for sample (3). the catalytic cracking processes were carried out at temperature range 325-400 ºc and initially at atmospheric pressure after 30 minutes over 9.88 % hy-zeolite catalyst load. the comparison between the conversion at different operating conditions of catalytic cracking processes indicates that a high yield was obtained at 375°c, according to gasoline production. the distillation of cracking liquid products was achieved by general astm distillation (astm d -86) for separation of gasoline fraction up to 220 ºc from light cycle oil fraction above 220 ºc. according to gasoline production, it can be noticed that the condition of the feed with the lowest initial boiling point (80 ºc) (sample 3) made it gives more production of gasoline as compared with the other feeds (sample 1,2). at the best temperature (375 ºc), for the best feed for the production of gasoline (sample (3)), the production of gasoline + kerosene were 19.315, 16.16 and 12.95 wt.% for sample (2, 3 and 1). the ron for the gasoline produced from the catalytic cracking for the feed of the lowest initial boiling point was 92.3. keywords: catalytic cracking, furfural extraction, lubricating oil. 1. introduction extract lubricating oil is a by-product of the furfural extracting process that applied in refinery process to develop the viscosity index of various kind of lubricating oil fraction. it is a totally rich aromatic content by-product which normally has black color, which identified by high polycondensed aromatics and some lubricating oil fraction and also by high viscosity [1,2]. the tires industry uses large amounts of an aromatic extract. on the other hand, lower amounts of it are utilized in plastic and rubber manufacture and asphalt blends. in spite of that the applications of aromatic extract are relatively limited [3]. these compounds are described as residuum aromatic extracts (rae) if the oil base stock produces in vacuum process and distillate aromatic extracts (dae) if it produces in atmospheric distillation [1,2]. the refinery process that is most popularly utilized for yielding gasoline of high octane value from heavy oils is catalytic cracking. this process utilizes to remove the sick effects of thermal cracking, like high carbon producing, the unsaturation of products. the reaction mechanism identifies catalytic decomposition from thermal decomposition and it is named as carbonium ion mechanism. the presence of this mechanism causes the yielding of extra stabilized saturated components having an excess attends for isomeric reactions. the steadiness of these ions are essentially controlled by the nature of molecule fatimah kadhim idan al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 100107 (2019) 101 submits cracking, then the conditions of decomposition [4]. the kind of the feedstock effect on the octane number of the produced gasoline, gasoline that has high octane number yields from a feed of high aromatic content except, the formation of coke on catalyst's surface is higher and the yielding of gasoline is lower. depending on the fact that the feedstock of high cycloparaffins content is extra efficient and simply separate yielding olefins, it provides medium quality and yield of gasoline, while the paraffinic feedstock is ready to decomposition and produce a larger gasoline's quantity having lower octane number as compared with those collected from cycloparaffins as well as aromatics including the largest transformation [5,6]. zeolites are microporous crystalline, hydrated aluminosilicates of alkaline earth metals or alkaline. its frameworks are consist of [sio�]�and [alo�]�tetrahedra that produce various open structure by sharing the corner. the negative charge of the lattice is offset by the positive charge of cations that placed at special sites of framework [7]. m /no·al o ·ysio ·wh o, is the practical formula for zeolite. where n is the cation valence ,y is 2–200, , and w describes the water consisted in the intracrystalline channels of zeolite [8].there are three types of manufactured zeolites are, a, x, y. for the purpose of adsorption and disconnection of normal alkanes from their mixtures with hydrocarbons of other kinds and for cleaning and drying of hydrocarbon gases from hydrogen sulphide and carbon dioxide , type a zeolites that have a pore diameter of 0.3-0.5 nm are utilized [9]. zeolite of type x have a pore size diameter of 0.8-1.3 nm and class y 0.8-0.9 nm. the general used zeolites are x and y. zeolite y remains to present the largest degree of catalytic stability with the largest yielding of gasoline with highest octane. the other molecular sieves and zeolites have lower product selectivity or they have been deficient in instability so they are generally unsuccessful [10,11]. syamsuddin et al. discussed the catalytic decomposition of atmospheric petroleum residue oil using a batch reactor at 340 ºc for 3 hours residence time at high-pressure. the conversion was 60-65 wt. % and the yield of gasoline was 11.5-13.37 wt. % [12]. esgair et al. studied the catalytic activity of faujasite type nay catalysts produced from kaolin (local clay) with various si/al ratio in the temperature range of 450-525° c, atmospheric pressure, weight hourly space velocity (whsv) of 5-20 h � , particle size ≤75µm. this process is carried out at an experimental laboratory plant scale of fluidized bed reactor. it was found that the cumene conversion rising with lowering whsv and rising temperature. the highest conversion 42.36 mol.% was at 525° c and whsv 5 h �, for catalyst with 3.54 si/al. the rapprochement of standard with that of the x-ray diffraction intended nay zeolite catalyst display that the catalyst is yzeolite. at the same operating condition and by utilizing the same clay for preparation , y-zeolite introduce larger transformation than x-zeolite [13]. mohammed et al. studied the catalytic cracking carried out at a laboratory plant scale of fluidized bed reactor for vacuum gas oil by utilizing the faujasite type yzeolite catalyst which prepared from kaolin that is locally available. the pore volume and surface area for prepared catalyst was 0.39 cm /g and 360 m /g respectively. the cracking process was carried out in the temperature range of 440 to 500 °c, weight hourly space velocity (whsv) range 10 to 25 h �,and at atmospheric pressure. the conversion at 500 °c and whsv 10 h � by utilizing faujasite kind nahy, nanh�y and nay zeolite were 69.5 %, 64.1% and 50.2 wt.% respectively. the productivity of gasoline utilizing the same operating conditions were 36.8% ,30.5% and 24.8 wt.% respectively [14]. rahman et al. studied the catalytic cracking conversion of iraqi vacuum gas oil on large and medium pore size (hy, hx, zsm-22 and zsm-11) of zeolite catalysts by utilizing a continuous fixedbed laboratory reaction unit. the processes are carried out at the range of temperatures of 673 to 823k, and lhsv range of 0.5-3 h �. it was found that the catalytic conversion of vacuum gas oil rises with temperature rising and decreasing in lhsv. the activity of catalyst arranged in this order: hy> hx> zsm-11> zsm-22. the kind of the catalyst and the temperature effect highly on the product distribution. hy zeolite catalyst produced higher hydrocarbon. the selectivity toward large octane number products for the suggested catalysts are arranged in this order: hy>hx>zsm-11>zsm-22 [15]. in the present work, the characterization of three feeds of extract lubricating oil, the performance temperature for catalytic cracking of the feeds using a fixed bed laboratory unit and hyzeolite, and the characterization as well as the composition of the produced gasoline were studied. fatimah kadhim idan al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 100107 (2019) 102 2. experimental 2.1 materials 2.1.1 feedstock the feedstock of this work is extract lubricating oil that yield in al-dora refinery by extraction process of lubricating oil stock. 2.1.2 catalyst the utilized catalyst for cracking process is hyzeolite catalyst provided from pye unicom company. the properties of this catalyst are presented in table 1. table 1, the properties of the catalyst characteristics value cylindrical size, mm 3 bulk density, g./ cm 0.8 si / al 3.95 average pore diameter, � 8 surface area, m /�. 210 2.2 the experimental unit the catalytic cracking experiments were carried out in fixed bed laboratory plant scale. fig.1 shows the diagram of this unit, that includes: 1. reactor volume (250 ml), 2. thermostat couple type k, 3. temperature controller, 4. electrical heater, 5. thermal insulator, 6. valves fitting. fig. 1. diagram of laboratory reactor unit. the reactor consists of stainless steel tube with 14 cm length and 5 cm inside diameter and 250 ml volume. it was controlled and heated automatically by one heater which insulated by the jacket and carried by the climb. the temperatures inside the reactor were measured by thermocouple fixed inside the reactor at the top. 2.3 the experimental procedure 105 ml of extract lubricating oil as a feed (1, 2 and 3) put in the fixed bed reactor unit, that heated at a various temperature (325, 350, 375 and 400 °c) for four runs at residence time (30 minutes) for each run using 10 gm of y-zeolite catalyst for each run. liquid produced as a result of cracking was distillated in astm d86. 3. results and discussion 3.1 distillation of the feeds (extract lubricating oil) the distillation curves for the three feeds of extract lubricating oil were shown in fig. (2, 3 and 4). the data of these figures are in table 2. as shown in table 3, it was noticed that the true boiling point distillation information gives an extra itemized description to extract lubricating oil volatility. the initial boiling point (ibp) for true boiling point distillation test is minimum as well as its end boiling point (ep) is higher as compared with the test of astm, the reason behind that is its separation degree is much higher from that of the test of astm distillation. the curve of tbp (sketch for normal boiling point (nbp) against sample distilled percent volume) is used like a principle for description the extract lubricating oil for purpose of analysis and design. listak and oja analyzed the variation between the actual average boiling points and astm d86 boiling points for continuous oil mixtures of shale oils that are “synthetic” crude oils yielded industrially from solid oil shale by pyrolysis, at 500 °c. there was noticed that the average boiling point collected for a cut using atmospheric boiling points was constantly minimum than the one collected from astm d86 distillation ''as an arithmetic average of the initial and final temperatures of the cut ''. this was noticed to be primarily due to an interplay between the residence time in the condenser and the heating rate of the sample. [16]. feed in feed out fatimah kadhim idan al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 100107 (2019) 103 fig. 2. astm d86 of sample 1. fig. 3. astm d86 of sample 2. fig. 4. astm d86 of sample 3. table 2, the astm distillation of samples. table 3, tbp of three type of feed the results from atmospheric distillation by astm d-86 for feeds and the true boiling point distillation (tbp) are used to calculate some physical properties after calculating the mean average boiling point. table 4, the physical and chemical properties of three samples for extract lubricating oil number of extracts temp. in °c vol. % 3 ibp =80 2 ibp =86 1 ibp=140 146 142 156 5 160 170 178 10 166 175 180 15 169 187 190 20 171 191 194 25 194 195 198 30 197 202 210 35 200 211 214 40 208 215 216 45 212 218 220 50 217 221 222 55 222 225 234 60 229 233 238 65 +229 +233 +238 +65 volume % true boiling point °c sample (1) sample (2) sample (3) 0 110 60 55 10 162 154 143 30 193 190 189 50 223 221 214 70 253 249 248 90 278 278 278 95 288 285 282 number of extract property 3 2 1 141 143.6 144 molecular weight (g/gmole) 0.964 0.965 0.972 specific gravity 15.28 15 14.08 api 214 218 221 mean average boiling point ( ��) °c 74.5 76 78 aniline point °c 25.36 25.35 24.27 diesel index 59 60.5 62.5 cetane index 1.547 1.546 1.544 refractive index 1.59 1.86 2.77 sulfur content % 24.77 26.87 30.6 aromatic content % 28 30.23 33.125 paraffinic content % 11.54 11.525 11.42 hydrogen content % 42.32 42.3 42. 3 heat content mj/kg astm d86 astm d86 fatimah kadhim idan al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 100107 (2019) 104 3.2 catalytic cracking liquid products of catalytic cracking which obtained at temperatures (325,350, 375 and 400 ºc) by batch laboratory unit were distilled at continuous wide range distillation unit (astm d86). the atmospheric distillation was continued until the temperature of the cracking product in the distillation flask reached 250 ºc to separate gasoline + kerosene fraction. table 5 displays the production of gasoline by catalytic cracking for the three samples at different temperatures (325,350, 375 and 400 ºc). tables (6, 7 and 8) display the catalytic decomposition outcomes at 375 °c for each of the three samples (sample 1,2and 3) respectively. figure (5) display the comparisons between the yield of gasoline and kerosene for catalytic decomposition of the three samples at 375 ºc. table 5, production of gasoline by catalytic cracking for the three samples at different temperatures. tempera ture (°c) vol. of gasoline fraction at 220 °c sample (1) sample (2) sample (3) 325 12 16 19 350 14 18 21 375 16 20 24 400 11 15 18 table 6, material balance of catalytic cracking of sample (1) at 375 °c. the fraction boiling range ºc %yield based on vol. %yield based on wt. gasoline 87-150 6 4.65 kerosene 150-250 10 8.3 coke 2 table 7, material balance of catalytic cracking of sample (2) at 375 °c the fraction boiling range ºc %yield based on vol. %yield based on wt. gasoline 80-150 8 6.2 kerosene 150-250 12 9.96 coke 3 table 8, material balance of catalytic cracking of sample (3) at 375 °c. fig. 5. vol. % and wt.% of gasoline + kerosene produced from three samples by catalytic cracking at 375 ºc. for each of the three samples, in this situation, catalytic activation proceeds in synchronism with thermal activation. addendum to that, rising within the position of active acid which can be utilized for reaction [17,18]. from table 5 it can be noticed that the best temperature in this work was 375°c. for each of these samples, production of unsaturated gasoline is the elementary step for extract lubricating oil decomposition and this product is commonly the required output. yet, the produced gasoline perhaps go under furthermore reaction which will be either oligomerization as well as cycloaddition for the compounds into dehydrogenated outputs as well as coke or subjected to side decomposition, which is commonly indicated to over decomposition, into gases component [19]. precipitated coke, as well as light side outputs, are produced by partly conversion of gasoline that produced like an intermediate output. each of these compounds minimizes the productivity of gasoline in the case of high amount of transformation for the extract lubricating oil. commonly, the transformation amount regulates in amount equal to that of the highest gasoline in order to prohibit the incidence of this process of decay that damage the profit of the process [5]. according to that the yield of gasoline increase until the run of (375°c) and reduce by increasing the temperature to 400 °. the mentioned results are agree with those mentioned by esgair [17] as well as maadhah et al. [18]. as shown in fig.5 the gasoline yield reaches the maximum in sample (3). as shown in table 4, all of the properties of extract lubricating oil samples are changed and there is not one property that changed in one feed the fraction boiling range ºc %yield based on vol. % yield based on wt. gasoline 76-150 11 8.525 kerosene 150-250 13 10.79 coke 1.5 fatimah kadhim idan al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 100107 (2019) 105 and being constant in other feeds, so according to that the study of the effect of the different kind of extract lubricating oil samples on the production of gasoline is complicated. the structure, as well as the productivity of gasoline, are highly respected for the kind of raw material. and so on, hydrotreated or paraffinic feedstocks yield higher gasoline as compared with non-hydrotreated or aromatic feeds. at high transformation for the feed, the presence of aromatics is favorable for the produced gasoline [20]. stratiev et al. studied the effect of 35 vacuum gas oils properties on reactivity, conversion, and yields in fluid catalytic cracking. it was found that at the catalytic decomposition of deferent raw materials, the content of saturated compound rises the reactivity of feedstock which also declines with the rising in the content of aromatic. the minimum aromatic content and higher saturated and hydrogen content of the feed cause higher conversion in catalytic decomposition [21] . depending on that sample (3) in the present work will give higher productivity of gasoline. the feed with the lower boiling point and lower gravity has higher h/c ratio and that made it produce higher yield of gasoline [22]. from table 4, sample (3) has the lower boiling point (214 °c) and lower specific gravity (0.964), depending on that it produces higher yield of gasoline. 3.3 the possibility of extract lubricating oil cracking uses the chemical composition of the produced gasoline using catalytic cracking from the sample (3) at best temperature (375°c) tested by utilizing piona test. table 9, the chemical compositions of cracked gasoline produced from sample (3) at 375 °c piona analysis total mass% n-paraffins 6.79 naphthenes 3.13 iso paraffins 37.91 aromatics 33 olefin 11.76 oxygenated 7.3 piona composition for gasoline that produced is described in table 9 ,which shows that the yielded gasoline has low olefins content in compared with gasoline produced by esgair [17], who explained that the olefins content in yielded gasoline is 34.1%. the reason for that may be hydrogen transfer reactions growing that in which olefins with naphthenes reaction produce paraffins as well as aromatics. naphthenic components are able to react with olefins yielding aromatics as well as paraffins because these compounds are hydrogen donors. since the extra reactive bonds are the double bonds are more reactive which simply polymerized as well as oxidized causing the production varnishes, as well as gums, injection nozzles and valves of automobiles, will be blocked due to the gasoline high olefin content [23]. it also can be noticed that gasoline which formed from this catalytic decomposition has a lot of aromatics as well as isoparaffins and that cause high research octane number (ron) for this product. toluene, 1,3-dimethylbenzene, and isobutyl benzene are the aromatic compounds that present in produced gasoline and those have high ron which is 111, 115, and 112 ron, respectively for each of them while isoparaffin compounds have high octane numbers (85-100) [24]. finally, it is able to utilize the gasoline that yielded by the decomposition of extract lubricating oil as a useful requisite gasoline for regular and premium automobile gasoline yield because the minimum research octane number of regular and premium iraqi gasoline are 85 and 90, respectively [25]. table 10 shows the characteristics of produced gasoline by catalytic cracking and required properties of this fraction. table 10, the characteristics of produced gasoline characteristics value catalytic cracking iraqi commercial value[25] specific gravity, 15.6ºc/15.6 ºc 0.8 0.775 api gravity 45.375 51.00 net heat, mj/ kg. 11000 11000 octane number 92.3 85 the gasoline has an octane number identical to the required. 4. conclusion the use of extract lubricating oil is almost limited but it has the ability to crack because of its high molecular weight so it was able to crack it to produce light fractions more valuable fuels. fatimah kadhim idan al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 100107 (2019) 106 the study on the effect of extract lubricating oil catalytic cracking in a fixed bed laboratory reactor shows that the increasing in reaction temperature from 325°c to 375°c gives higher yield of gasoline. after this temperature the yield decrease because the gasoline itself will crack and light cycle oil yield increase in the run of 400 °c. based on the maximum yield of gasoline it could be said that the best cracking temperature was 375ºc. feed with lowest initial boiling point (sample 3) gives more gasoline yield. gasoline yield increase in the run of 375 °c for sample (3) where it is 19.315 wt.%. from the piona analysis, the produced gasoline has high research octane number because it has high isoparaffins and aromatics. this means that it is possible to use gasoline for the automobile. 5. references [1] r. sadeghbeigi, “fluid catalytic cracking handbook: design, operation and troubleshooting of fcc facilities. 2000.” gulf publishing company. houston, tx, 2000. 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[25] ministry of oil republic of iraqi,“marketing specification guide of iraqi petroleum,” 2013. )2019( 100107، صفحة 2د، العد15دجلة الخوارزمي الهندسية المجلم فاطمة كاظم عيدان 107 مستخلص زيوت التزييت بالتكسير باستخدام عامل مساعد إلنتاج معالجة المتبقي من ةمقاطع خفيف ***سليم محمد عبيد *فاطمة كاظم عيدان جامعة النهرين /كلية الهندسة/ قسم الهندسة الكيمياوية*،** shemeriya93@gmail.com :االبريد االلكتروني saleem_mo71@yahoo.com :البريد االلكتروني الخالصة ً منتجبوصفها يتعامل هذا البحث مع التكسير الحراري والتحفيزي لثالث عينات من مستخلص زيت التزييت المنتج ً ثانوي ا من وحدة االستخالص باستخدام ا . نقطة الغليان األولية لهذه المنتجات هي: fixed bedفي ظروف تشغيل مختلفة في مفاعل مختبري من نوع الفيرفرال لزيوت التزييت في مصفى الدورة س في البداية في الضغط الجوي° ٤٠٠-٣٢٥). تم تنفيذ عملية التكسير في نطاق درجة حرارة ٣س للعينة (° ٨) و ٢س للعينة (° ٨٦)، ١س للعينة (° ١٤٠ لتكسير باستخدام العامل المساعد ان افضل نسبة لبين نسب التحويل في الظروف المختلفة ة٪ من الزيواليت. لقد بينت المقارن ٩٫٨٨باستخدام دقيقة ٣٠ لمدة و ذلك لعزل ) (astm d -86س اعتمادأ على الكازولين الناتج. تم تقطير سائل التكسير الناتج من العملية باستخدام (° ٣٧٥تحويل كانت عند درجة حرارة س . إن ظروف الماده الداخلة للتفاعل و التي تحمل ° ٢٢٠س عن المقاطع االخرى في درجات حرارة اعلى من °٢٢٠كازولين عند درجة حرارة تصل الى ال ألفضل س)° ٣٧٥(عند افضل درجة حرارة ).٢،١(العينة االولية واد الم بقية س جعلته يعطي إنتاج اعلى للكازولين مقارنة مع° ٨٠أقل نقطة غليان أولية الرقم .بالوزن %١٢٬٩٥ ) ١و للعينة ( ٪ بالوزن١٦٬١٦) ٢و للعينة ( ٪ بالوزن ١٩٬٣١٥ر الكازولين + الكيروسين عند التكسيكان انتاج ) ٣(العينة عينة .٩٢٫٣أولية كان مادة االولية التي تحمل أقل نقطة غليان الاالوكتاني للكازولين الناتج من التكسير الحفزي من vibration characteristics of oblate shell with and without framed structure al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 6, no. 2, pp 1-10 (2010) vibration characteristics oblate shell "with and without framed structure" kadhim h. ghlaim* hatem r. waseem** * department of mechanical engineering/ dijlah university college ** department of mechanical engineering/ engineering college/ university of baghdad (received 27 october 2009; accepted 28 april 2010) abstract this paper presents the results of investigating the vibrational characteristics of oblate dish with and without framed structure . a finite element method, was applied to the dynamic analysis of oblate spheroidal shell. different types of elements were considered in one dimension and two dimensions. it was found that the natural frequencies of oblate shells had two types of behavior against increasing the shell thickness and eccentricity, which are the membrane mode and bending mode –since – the membrane modes natural frequencies tend to increase with the increasing the eccentricity of oblate, while the bending modes natural frequencies decrease with the increasing the eccentricity till reach the optimum eccentricity. experimental validation tests have been carried out on the spheroid dish by using the model analysis technique. keywords: vibration, structure. 1. introduction when the large structure such as aircrafts, bridges, ships, vehicles and tall building being constantly acted on by wave and motion, the resulting forces can introduced vibrations at the resonance or repeated many times which may lead to structural failure. an essential requirement of an engineering structure is to sustain the loading applied to it during service life without failure. to insure that and to obtain an optimum design of structure the dynamic characteristics must be established. the dynamic characteristics of any structure are governed by its stiffness and mass properties. the most important dynamic characteristic of the structure is the natural frequencies which are a function of material constants and dimensions of structure. it is worthy to indicate the industrial applications and important of plates and shells structure. one of important used type of elastic thin shells which has a particular interest is the oblate shells. the oblate type of shell has many practical applications, one interesting application includes the protective shell used as the housing of the early-warning scanner of the airborne warning and control system aircraft (awacs). the study of the dynamic analysis of plates and shells has been treated by many investigators using different methods. the oblate spheroidal shells considered extensively have been restricted to few works, benzes and burgin [1] were solved the problem of the free vibration of thin isotropic oblate shells using galerkin‟s method. penzs [2] was extended this work to include thin orthotropic oblate shells. curved blades can be modeled approximately by fact element [3]. curved shell elements may provide a more accurate facility for the finite element modeling of curved blades. the basic equations which describe the behavior of a thin elastic shell were originally derived by loue [4]. pawsey [5] explained the basic problems common to most shell elements, and which restrict most elements class of shells, either thin or thick, depending on the parent theory used for developing the element. recently the concept of quasi comparison function has been introduced for the reylegh ritz discretization in self-adjoint eigen-value problem [6]. babich [7] is studied the kadhim h. ghlaim al-khwarizmi engineering journal, vol. 6, no. 2, pp 1-10 (2010) 2 stability and natural vibrations of shells with variable geometry and mechanical parameters. 2. numerical procedure general large number of different theories has been derived by various scientist, all purposing to static and dynamic analysis of shells. differences among these theories are due to various assumptions-shells theories most incorporate bath flexural and extensional deformations. a structure, such as a dish, may have zones with the variable thickness and construction when it is difficult to use one element type. if a mindlin facet element is employed for a thin structure shear looking will occur and will lead to inaccurate results. the flat or facet shell element is the appropriate and easily employed for curved shells. two basic facet shell elements are introduced. the kirchoff facet element based upon a combination of the 2-d plane stress element and the thin plate bending element. thick facet element is based upon a combination of the 2-d plane-stress element and the mindlin plate element. boundary conditions the dish is assumed to be clamped at two support legs and free at all other points. the boundary conditions for the clamped point may be written as follows:  iii wvu 0 at clamped ends. xi = 0 ziyi  at clamped ends. another type of boundary conditions were considered which are concerned with the half oblate shell. this shell was clamped at its peripheral base. the three components of translation and three components of rotation of all nodes of the oblate shell peripheral base are assumed equal to zero. governing equations the finite element procedure for the estimation of natural mode shape and natural frequency of oblate dish can be formulated by using facet element and the principle of minimum potential energy theorem. express the total potential of the element in terms of nodal, displacements, if the minimum total potential energy theorem is used, then the equilibrium* equations for the clement can be established. the total potential energy for the element can be defined as follows [8]: x = u -w where x is the total potential energy of the element, u is the strain energy of the element, w is the work done by external force f: w=f. where  is the nodal deformation. it can be deduced that    dxdydzbzbdbzbk bm t b t m t tl )()(2 2 …(1) then it can be proved that: bml kkk  dxdybdbtk mmm   dxdybdbtk bbb   m: hold for membrane b: hold for bending kl: local stiffness matrix of the element similarly, mass matrix can be deduced that: dxdyndnm dxdyndnmwhere mmm bb t bb mm t mm bm      …(2) where n is the shape function. for thick facet element, the transverse shear strain was considered in addition to the membrane and bending strain. the nodal dynamic equation for oblate shell is ....)()()()( tftktctm    and for undraped free vibration the equation of motion become. 0)()(  tktm  …(3) fig.(1) illustrated the flow chart of the above equations. fig.(2) shows the used mesh of the oblate dish. kadhim h. ghlaim al-khwarizmi engineering journal, vol. 6, no. 2, pp 1-10 (2010) 3 fig.1. flow chart of the finite element analysis. fig.2. mesh of the oblate shell. input data calculate k matrix    dxdydzbzbdbzbk bm t b t m t t )()(2 2 bm kkk  , dxdybdbtk mmm   dxdybdbtk bbb   calculate m matrix dxdyndnm dxdyndnm mmm bb t bb mm t mm bm      solve the equation 0)()(  tktm  to get the natural frequencies kadhim h. ghlaim al-khwarizmi engineering journal, vol. 6, no. 2, pp 1-10 (2010) 4 the standard solution of dynamic problem the major problem in structural analysis using the fem is the solution of a set of simultaneous algebraic equations. iterative methods are those which start with an initial approximation and which by applying a suitable chosen algorithm, leads to successively better approximation. when the process converges good approximate solution is expected to be obtained. the accuracy and the rate of convergence of iterative methods vary with the algorithm chosen, the common approaches used for iterative solution are simple iteration method, subspace operation technique with the static and dynamic condensation, the basic steps of simple iteration and the subspace iteration algorithm can be found in [9, 10 ] 3. experimental model experimental values were obtained for two models which were constructed from steel. the dimensions for the two models are given in table(1). table 1, specifications of tested models parameter model (1) values & units model (2) values & units radius of shell curvature (r) 650 mm 650 mm radius of dish end (r) 75 mm. height of dish end (h1) 92 mm. 135 mm. the extended edge height (h2) 20 mm. total height of half shell (h) 92 mm. 155 mm. modulus of elasticity ( e ) 208 gpa 208 gb1 density (  ) 7850 kg\m3 7850 kg\m3 poisons ratio ( ) 0.3 n. d 0.3 n. d basically, each one of the models was constructed as follows. for each model a flat sheet of plate was cut to proper dimensions as shown in fig.(3). after fraction of the circular plate on the bench of the pressing machine and by using a suitable press die moving up and down to impact the circular plate several times get on the dish end as shown in fig.(3.b). repeat the pressing operation with another dies to obtain the final half shell member as shown in fig.(3.c). locate the position of legs and make two holes in one half shell and then use the welding method to fix the two legs in its position. fit, precisely the edges of the two half shell then welded together. the welding was ground flat on the outer surface of shell to obtain on the two models as shown in fig.(3). fig.(4) shows a block diagram for different equipments and instruments used in testing the models. the experimental work was carried out to measure the natural frequencies of the two oblate dishes. the results of experimental and theoretical approaches as listed in table (2) and table (3). a natural frequency was distinguished by observing the sharp increase in maximum amplitudes of the output signal and by the intensity of the acoustic tone emitted with phase angle. table 2, natural frequencies (hz) of dish model i mode exp. of frequencies theo. frequencies discrepancy % 1 69 67.51 2.15942 2 173.5 169 2.59366 3 180 176 2.222222 4 325 318.2 2.092308 5 356 347.6 2.359551 6 455 442.6 2.725275 7 882 854.3 3.14059 8 1126 1085 3.641208 9 1150 1127 2 10 1213 1173 3.297609 kadhim h. ghlaim al-khwarizmi engineering journal, vol. 6, no. 2, pp 1-10 (2010) 5 fabrication and processing step of model fig. 3. types of models. acircular plate ds circular plate with variable ds ts boblate head 650 r 9 2 oblate head with 5mm thickness r=650mm r r 650 cshallow head 1 5 5 ts shallow head with 5mm thickness after forming , r=650mm, r=75mm r=65 0  650 9 2 9 2 1 1 5 140*140*5 thick. 40*40*3 thick. 5 wl . 650 1 5 5 1 5 5 1 1 5 140*140*5 thick. 40*40*3 thick. wl . 140 140 head 5mm,efter forming r=650,r=75 kadhim h. ghlaim al-khwarizmi engineering journal, vol. 6, no. 2, pp 1-10 (2010) 6 fig. 4 block diagram of dynamic measurement system. multiplexer lissitous display data controller group selector charge amplifier b&k2635 model level phase control vibration exciter control recorder b&k2034 analyzer 20 channel amplifier force transducer (1) accelerometer (2) (2)b&k 4391 (1)b&k 2806 vibration exciter b&k2706 hp. computer kadhim h. ghlaim al-khwarizmi engineering journal, vol. 6, no. 2, pp 1-10 (2010) 7 table 3, natural frequencies ( hz) of dish model ii mode exp. of frequencies theo. frequencies discrepancy % 1 45 39.47 12.28889 2 141 131.5 6.737589 3 181 175.6 2.983425 4 211 202.5 4.028436 5 218 223 -2.29358 6 229 224.4 2.008734 7 232 226.9 2.198276 8 305 297.5 2.459016 9 424 413 2.59434 10 431 422.7 1.925754 4. discussion and conclusion in the foregoing work it is demonstrated how the finite element method and experimental model analysis, can be employed to determine the free vibration frequencies and mode shapes of simplified representation of oblate dish. the comparison of predicted and measured natural frequencies are written acceptable engineering agreement for the system tested. two types of results are recorded in tables (1) and (3). figure (5) and figure (6) show the variation of natural frequencies with the mode number of experimental and theoretical results. figures (7) and (8) show the natural frequencies of vibrations as function of the shell thickness once of the eccentricity value e = 0.925 once again for half oblate of eccentricity e = 0.585 clamped at its peripheral base for several modes. natural frequencies are seen to have two types of behavior against increasing the shell thickness. one type, which is associated with the membrane modes, remain unaffected by the thickness variations, which the other type, which is associated with the bending modes. tends to increase with the thickness. the dynamic behaviour of oblate shells depend upon the coupling and uncoupling of membrane modes and bending modes. it was found that when the eccentricies of oblate increase the natural frequencies will be increase until reading an optimum value of eccentricities. after ; the optimum value of eccentricity, the natural frequencies will be decrease until the oblate shell becomes circular plate ( e = 1 ) as shown in fig (10), while fig (9) show the effect of shell thickness on the von mises stresses of oblate clamped at its peripheral base. fig.5. experimental results of natural frequencies versus mode for oblate dish with (a=325, b=92mm, ts=5mm, mat: steel alloy). fig.6. theoretical results of natural frequencies versus mode for oblate dish with & without internal structure with (a=325, b=55mm, ts=5mm, tp=3mm, mat: steel). 0 1 2 3 4 5 6 7 8 9 10 11 mode 0 400 800 1200 n a tu ra l f re q u e n c ie s (w n ) in h z theoretical results zienkiewicz, plane stress element experimental results for theo. results (nn=508, ne=1004, dof=3036) 0 1 2 3 4 5 6 7 8 9 10 11 mode 0 400 800 1200 1600 n a tu ra l f re q u e n c ie s (w n ) in h z dish with internal structure. dish without internal structure. zienkiewics, plane stress element for shell. tom, beam ele. for beam. for dish without int. struct. (nn=508, ne=1004, dof=3036) for dish with int. struc. (nn=606, ne=1196, dof=3512) kadhim h. ghlaim al-khwarizmi engineering journal, vol. 6, no. 2, pp 1-10 (2010) 8 fig.7. the effect of shell thickness on the frequencies of half oblate shell clamped at peripheral base with (a=185mm, b=70mm, e=925mm, mat: aluminum). fig.8. the effect of shell thickness on the frequencies of half oblate shell clamped at peripheral base with (a=125mm, b=150mm, e=585mm, mat: aluminum). fig.9. the effect of shell thickness on the von misses stress of oblate shell clamped at peripheral base with (a=185mm, b=70mm, e=925mm, mat: aluminum). fig.10. the variation of critical von misses stress of oblate shell for half oblate spheroids shell clamped at its peripheral base with (a=185mm,b=70mm,e=925mm,mat: aluminum). kirchoff, plane stress element, n=1 kirchoff, plane stress element, n=4 kirchoff, plane stress element, n=7 kirchoff, plane stress element, n=10 membrane, plane stress element, n=1 membrane, plane stress element, n=4 nn=121, ne=228, dof=654 0 1 2 3 4 5 6 7 8 9 10 11 thikness (t) in mm. 0 1000 2000 3000 4000 5000 6000 n a tu ra l f re q u e n c ie s (w n ) in h z kirchoff, plane stress element, n=1 kirchoff, plane stress element, n=4 kirchoff, plane stress element, n=7 kirchoff, plane stress element, n=10 membrane, plane stress element, n=1 membrane, plane stress element, n=4 nn=121, ne=228, dof=654 0 1 2 3 4 5 6 7 8 9 10 11 thikness (t) in mm. 0 1000 2000 3000 4000 5000 6000 n a tu ra l f re q u e n c ie s (w n ) in h z 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 eccentricity (e) 0 10 20 30 40 50 60 70 80 90 100 v o n m is si s st re ss i n n /m m first mode. second mode. kirchoff, plane stress element 0 1 2 3 4 5 6 7 8 9 10 11 12 thikness (ts) in mm. 0 5 10 15 20 25 30 35 40 v o n m is si s st re ss i n n /m m first mode. second mode. kirchoff, plane stress element (nn=191, ne=260, dof=554) kadhim h. ghlaim al-khwarizmi engineering journal, vol. 6, no. 2, pp 1-10 (2010) 9 5. references [1] penzes, l., and burgin, g. „free vibration of thin isotropic oblate spheroidal shell‟, general dynamics report no. gpic-btd 65113, 1965. [2] penzes, l. „free vibrations of thin ortotropic oblate spheroidal shell‟, j.a coust soc. amer, vol. 45, pp-500-505 1969. [3] zienkiewicz, o.c. „the finite element method, mcgraw-hill book co.,1992. [4] loue, a.e.h. „a treaties on the mathematical theory of elasticity‟, 4 th ed., dover publication, new york, 1983. [5] pawsey, s.f. „the analysis of moderately thick to thin shells by the finite element method‟, 1985. [6] hagedran, p. „ the rayleigh-ritz method with quasi-comparison functions in non selfadjoint problems‟, tranaction of the asme,vol.115, pp (280-281),1993. [7] babich d.v. andn khoroshan “ stability and natural vibrations of shells with variable geometric and mechanical parameters”, international applied mechanics, vol. 37, no. 7 , 2001 [8] daniea j. inman „engineering vibration, third addition‟, person education inc., printing hall, 2008. [9] meyer, c. „solution of linear equations‟, state – of the art, ascej. of structure, dw. vol 99, pp1507-1526, 1979. [10] melosh, r.j, and „efficient solution of load deflection equations‟, ascej. of structure div., vol 95 pp 661-676, 1969. (2010 ) 10-1 ، صفحة2، العذد 6مجلة الخىارزمي الهنذسية المجلذ كاظم حمزة غليم 10 خواص االهتزازات لمصفائح المنبعجة بأضافة او عدم اضافة االطار الهيكمي ** حاتم رحيم وسمي* كاظم حمزة غليم كهٍت دخهت اندايؼت االههٍت / لسى انهُذست انًٍكاٍَكٍت * خايؼت بغذاد / كهٍت انهُذست/ لسى انهُذست انًٍكاٍَكٍت** :الخالصة )حٍث تى استخذاو طشٌمت انؼُاطش انًحذدِ . فً هزِ انذساست تى تحهٍم خىاص االهتضاصاث نهظحىٌ انًفهطحت بأستخذاو االطش انهٍكهٍت او بذوَها f.e.m) فً انتحهٍم انُظشي نتحذٌذ انخىاص انذٌُايٍكٍت نهزا انُىع يٍ انظفائح وغانباً ياتستخذو هزِ انؼُاطش فً تحهٍم انخىاص انًٍكاٍَكٍت نهظفائح حٍث تى حساب انتشدداث انطبٍؼٍت نًُىرج طفٍحت يُبؼدت طبماً نحانتٍٍ هً صٌادة سًك انظفٍحت . انًُبؼدت انكشوٌت وشبت انكشوٌت بأتداة واحذ او بأتداهٍٍ واناليشكضٌت نها يغ االخز بُظش االػتباس تحذٌذ ياٌكافئ فً تهك انتشدداث يٍ َسك االَحُاء وانُسك انغشائً ، حٍث اٌ انُسىق انغشائٍت نالهتضاصاث انطبٍؼٍت تضداد بضٌادة انالستمشاسٌت نظفٍحٍت انًُبؼدت بًٍُا َسىق االَحُاء تمم بضٌادة اناليشكضٌت نهظفٍحت وتستًش هزِ انحانت هكزا حتى َظم بانفحض انى انحانت ((االواكس ))وكزنك تى اخشاء تداسب ػًهٍت نفحض االهتضاصاث ػهى ًَىرج تى تظٍُؼت نًٍثم طحٍ دواس نطائشاث االَزال انًبكش . انًثانٍت ناليشكضٌت .حٍث تى انحظىل ػهى َتائح يثانٍت تى يطابمتها يغ انتحهٍالث انُظشٌت 74 al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 4, no. 3, pp 74-84 (2008) zinc oxide hydrogen sulfide removal catalyst/ preparation, activity test and kinetic study karim h. hassan*, zuhair a-a khammas** and ameel. m. rahman*** department of chemistry, college of science, university of diyala, baquba, iraq, e-mails: * drkarim53@ yahoo.com ** dr_zuhair52@ yahoo.com ***department of biochemical engineering, al-khwarizmi college of engineering, university of baghdad, jadiriyah, baghdad, iraq, e-mails: explorerxp50@yahoo.com (received 10 march 2008; accepted 10 september 2008) abstract hydrogen sulfide removal catalyst was prepared chemically by precipitation of zinc bicarbonate at a controlled ph. the physical and chemical catalyst characterization properties were investigated. the catalyst was tested for its activity in adsorption of h2s using a plant that generates the h2s from naphtha hydrodesulphurization and a unit for the adsorption of h2s. the results comparison between the prepared and commercial catalysts revealed that the chemical method can be used to prepare the catalyst with a very good activity. it has observed that the hydrogen sulfide removal over zinc oxide catalyst follows first order reaction kinetics with activation energy of 19.26 kj/mole and enthalpy and entropy of activation of 14.49 kj/mole and -220.41 j/mole respectively. keywords: zno, h2s, absorbent; reformate; cos, hydrodesulfurization; kinetics. 1. introduction the natural gas can be considered as the main raw material for fertilizer and petrochemical industries, in addition of being the main source of gas fuel. hydrogen sulfide is poison material with unpleasant odor and corrosive in addition of being poison for most industrial catalysts [1]. unfortunately, hydrogen sulfide is present in an appropriate amount in natural gas that affect the efficiency of catalysts used in fertilizer production. accordingly it must be removed it from the feedstock. several chemical methods have been employed for hydrogen sulfide removal such as phosphate method, iron oxide method, the hydroxide method, activated carbon adsorption method, molecular sieve method and the zinc oxide method [2]. of these zno catalyst method proved to be the most effective for sulfur compounds removal and h2s in particular.from the standpoint of high h2s removal efficiency, zinc oxide is more attractive than iron oxide because of more favorable sulfidation thermodynamics [3]. zinc oxide catalyst is used as a mixture of zno and alumina as a binder in addition to some fillers or binder materials. in general 90 wt % of zno is quiet acceptable. the function of the catalyst depends on the chemical reaction between the catalyst and hydrogen sulfide to form zinc sulfide: zno + h2s zns + h2o …(1) the quantity of hydrogen sulfide being adsorbed by zinc oxide depends on its value in the feed and on the degree of contact between it and the zno bed. many methods have been used for preparation of zno catalysts, but the most common were allocated between the thermal and chemical treatments. the thermal method involves the combustion of zinc metal with air in which zno mailto:drkarim53@yahoo.com mailto:dr_zuhair52@yahoo.com mailto:explorerxp50@yahoo.com karim h. hassan al-khwarizmi engineering journal, vol. 4, no. 3, pp 74-84 (2008) 75 with surface area of 10 m 2 /gm was obtained [4]. khammas et al. [5] have prepared zinc oxide catalyst from zinc oxide by-products purified by thermal methods treatments and th pure 95% zno was slurried with alumina and water and formulated to extrudates shape , dried at 130-150 o c and calcined at 700 o c for two hours . more than 90% h2s adsorption was achieved. the chemical or wet method that is used to prepare catalysts by precipitation method is summarized by precipitating the zinc from its salts and then drying and calcining the precipitates at 300-350 o c to form zno [6]. other important works on the zno catalysts was done by susan et al [2]. they prepared a regenerable zinc oxide-titanium dioxide sorbents for high temperature h2s removal from fuel gases. in addition to zno catalyst, other sulfur compounds removal catalysts were studied by several investigators. jiang et al. [7] studied the γalumina supported na2co3, k2co3 and cuo for flue gas desulphurization where regenerable adsorbents can recover sulfur as more valuable products such as sulfuric acid. they prepare all the adsorbents based on the principle of spontaneous monolayer dispersion of oxides or salts on high-surface-area supports and characterize them with xrd, bet, and xps. they find an excellent correlation between the maximum adsorption capacity of so2 and the monolayer loading of na2co3, k2co3, or cuo on γ-alumina. vohs and halevi [8] developed a mechanistic studies of the interaction of so2, h2s and organo sulfur compounds, such as thiols and disulfides with metal oxide surfaces and makes use of tpd (temperature programmed desorption) of probe molecules to measure reaction kinetics and energetic and surface sensitive spectroscopic probes such as xps (x-ray photoelectron spectroscopy) and hreels (high resolution electron energy loss spectroscopy) to identify stable surface intermediates. the apparent kinetics [9] of h2s removal by a zno-mno desulfurizer were studied by thermogravimetric analysis. the experimental results show that the reaction is first order with respect to h2s concentration. in the temperature range 200-400°c, the rate was controlled, at lower temperatures, by the grain surface reaction rate and, at higher temperatures, by the rate of intrapellet diffusion, respectively. the apparent kinetic behavior could be modeled by the equivalent grain model. the activation energies of surface reaction and solid diffusion were determined to be 11.842 and 20.865 kj/mol, respectively. an optimum reaction temperature was observed. reasons for this and why the solid diffusion activation energy exceeded that of the surface reaction are proposed. the aim of the present work is to prepare zno catalyst by a combined chemical treatment and test its activity and performance for the hydrogen sulfide removal from a natural gas. 2. experimental materials chemicals: sodium bicarbonate nahco3 solution of 1m, aluminum oxide al2o3, (it is possible to use aluminum hydroxide or aluminum nitrate instead), iodine, zinc metal, sodium thiosulphate, barium chloride, starch indicator and hydrochloric acid, all of which were of analytical grade (bdh). zinc nitrate zn(no3)2.4 h2o, since it is very dehydrated, it was prepared experimentally by dissolving zinc metal in dilute nitric acid. gases: nitrogen, compressed air, hydrogen was supplied from local gas factory supplier. como catalyst: commercial cobalt molybdenum sulfur removal catalyst como type (3e-124 hd). naphtha: heavy naphtha that is produced in daura refinery in baghdad and certified to contain 0.07 % sulfur. 3. catalyst preparation since most of the zno catalysts consist of more than 90% of zno, we choose to prepare the one with 90 wt% zno and 10% of alumina to avoid problems associated with tableting and hardness. the required amount of zinc nitrate that give 90 wt % of zno was dissolved in water and then 10% alumina was mixed together and heated to 60-70 o c with stirring and then sodium bicarbonate precipitating agent is added gradually with stirring and monitoring the ph of the solution during the addition until it reaches a value of 7. the precipitate is left to settle for two hours and then filtered off and washed with distilled water for several times to remove any excess bicarbonate that may present. the paste formulated as extrudates of 4×5 mm diameter in small laboratory extruder and then dried in an oven at 110 o c for 12 hours and then cooled to room temperature and finally calcined in karim h. hassan al-khwarizmi engineering journal, vol. 4, no. 3, pp 74-84 (2008) 76 a furnace at 450 o c for two hours, the temperature of which was raised gradually at a rate of 5 o c /minute. 4. chemical analysis and characterization zns was determined by treating the spent catalyst with dilute hydrochloric acid and the liberated hydrogen sulfide is then reacted with standard iodine solution [10-11]. the excess iodine was back-titrated with standard sodium thiosulphate in the presence of starch as indicator. for h2s determination a measured volume of the gas containing the h2s was passed into a solution of cadmium sulfate where yellow precipitate cds is formed [10-11]. the precipitate thus formed is treated with dilute hydrochloric acid to liberate the hydrogen sulfide which is then analyzed as mention above. the metal content of the catalysts were determined by standard atomic absorption method. pore volumes and densities were determined by liquid impregnation method [12]. hardness was determined with the erweka.tbh28 hardness meter [13] while crushing value was determined by placing 25 gm of the sample under pressure of 18kn for 20 minutes and measure the amount of powder that pass through 53 micrometer mesh as a percent relative to the total weight. 5. laboratory catalyst testing unit: activities of the catalysts for adsorption of h2s were determined by using a plant that consists of two units, the first one for generation of the hydrogen sulfide by the hydrodesulphurization (hds) of naphtha that contain 0.07 wt % of sulfur using a commercial cobalt molybdenum catalyst (como), and the second one for the adsorption of the gas on zno catalysts. the first unit is a continuous flow plant (fig.1). the reactor was made of stainless steel (316-heat resistant), length 800 mm, inside diameter, 19 mm. heaters were in the form of four separately heat-controlled block shells. the reactor was packed with 110 ml of the como catalyst between two layers of inert porcelain. test conditions were: reactor temperature 612°k; pressure, 25bar; flow rate of naphtha, 0.08 liter/hour; flow rate of the gas produced, 18 liter/hour. in a typical run the reactor was purged with n2 gas and the temperature rose. after establishing steady state conditions, the reaction was started; the naphtha hydrogen mixture was pumped upwards into the reactor. the products were passed through a high pressure separator and condenser to separate the liquid desulfurized naphtha from the gas containing h2s which leave the unit and enter the adsorption unit. the second unit used for the adsorption of h2s includes a quartz tube reactor of 17.5mm diameter and 350mm length placed in a heat controlled tubular furnace. the gas containing h2s is passed from one side of the reactor and leave from the other side of it after being passed over catalyst bed. test conditions were: reactor temperature 553-613°k ; pressure is atmospheric; flow rate of the gas produced were between 12-18 liter/hour which gives space velocity ranging between 8001200 hr -1 as 15ml catalyst volume was used. analysis of the gaseous products and the catalyst was carried out periodically whatever it is necessary. fig. 1. flow diagram of laboratory hydrodesulphurization unit. 1-feed tank for naphtha 2-ball valve 3-pump 4-one way valve 5-heater 6-pressure gauge 7-pressure control valve 8-heaters 9-temp. thermocouples 10reactor 1 0 8 heater 10 reactor 0utlet gas thermocouple 9 tubular furnace to heating control to temperature control 6 7 1 5 2 4 h2 3 karim h. hassan al-khwarizmi engineering journal, vol. 4, no. 3, pp 74-84 (2008) 77 6. results and discussion the physical and chemical properties of the prepared zno catalyst given in table (1) illustrates that they are quiet similar to the properties of the commercial catalyst.there is a slight difference in the values of hardness and crushing values which may be due to the purity of the material used in the preparation [14-15] and the extruder that is used in the formulation. the values of densities are quiet consistent with the expected differences between them, a slight yellow color was observed in the prepared catalysts resulted from purity of the raw material used and improper time of calcinations. the capability of the catalyst for adsorption of the h2s was observed by passing the gas containing h2s on its surface as explained in the experimental section. the flow rate of naphtha was 1cm 3 /min i.e, 60 cm 3 / hour which is equivalent to 41.4 gm/hour considering the density of naphtha to be 0.6900 gm/cm 3 . on supposing 100 % sulfur removal from the naphtha that contains 0.07 wt% of sulfur means that the rate of sulfur passing over the zno bed is about 0.029 gm s/ hour or 0.030 gm h2s / hour. by considering the flow rate of the gas leaving the hds unit to be 0.3 liter/min or 18 liter/hour resulted that the gas leaving the hds unit should contain 0.0017gm h2s /liter. practically the amount of h2s adsorbed was calculated by two means, the first one from the gas analysis for h2s and the second one from the catalyst analysis after adsorption. the chemical analysis and calculations of the amount of h2s in the gas leaving the hds unit indicated that the value is 0.0016 gm h2s/liter or 0.0288 gm h2s/hour, this is the amount that is really passed over the catalyst zno bed at the previously described conditions. the theoretical amount of h2s that should be adsorbed by the catalyst was calculated by considering that we used a catalyst bed of 15 gm of 90% zno i.e the net is 13.5 gm of zno. since 1 mole of zno (81gm) adsorbed 1 mole of h2s (34gm) means that 13.5 gm must adsorb theoretically 5.66 gm of h2s which means that the catalyst can operate for 196 hours before saturation is observed. passing the gas over the catalyst bed of 15 gm was continued for a period of 150 hours with continuous monitoring of the existence of h2s in the exit gas by a solution of cadmium sulfate which shows no indication about its existence at all as the yellow precipitate of cds did not form. for 150 hours operation on the catalyst with rate of h2s passing on it of 0.0288 gm / hour as calculated above, the mount of h2s adsorbed on the catalyst should be 4.32 gm. chemical analysis of the catalyst used after this period of time for sulfur revealed that the catalyst weight is 17.03 gm and contains 12.32 gm of zns, 3.21 gm of unreacted zno and 1.50 gm of alumina. this indicates that it consists of 79 wt% of zns and that the catalyst adsorbed 4.32 gm of h2s during its operation, a value that is equal to the theoretical one and mean that catalyst is operated with more than 99% efficiency during this period of time and it is still active and can be used for further time as expected theoretically and experimentally from the left unreacted and unchanged zno after 150 hours of performance. in industrial application the story is different from the theoretical one, as for example the catalyst of the iraqi north fertilizer company unit was replaced by a new one even it contains only 75 wt% of zns to a void problems associated from sudden saturation that results from unexpected increase in the dose of h2s. this is usually depends on the conditions of its use and the dose of h2s that pass over and according to the origin and source of the gas which its compositions is sometime fluctuated and cause a problem. table 1 properties of the prepared and commercial zno catalysts. properties prepared catalyst commercial catalyst two form extrudates extrudates color white to yellow white size (mm) 4 x 5 4-5 x 5-7 packing density, gm/cm3 1.22 1.18 particle density, gm/cm3 2.22 -- skeletal density, gm/cm3 3.23 -- porosity 0.31 0.28 pore volume, cm3/gm 0.25 0.23 hardness, n 8 10 zn, % 72 72.2 zno, % 89.7 90 al2o3, % 10.3 10 crushing value, % wt 9.5 8.5 karim h. hassan al-khwarizmi engineering journal, vol. 4, no. 3, pp 74-84 (2008) 78 7. kinetic of the hydrogen sulfide removal over zno catalysts the experimental data were fitted (16-21) to a simple power-law rate equation (2) for first order: ln [h2sin /h2sout] = k /lhsv …(2) where h2sin is the concentration of hydrogen sulfide, gm/l in the inlet gas to the reactor and h2sout is the concentration of the hydrogen sulfide in the outlet gas from the reactor, k is the rate constant, with the unit of hr -1 and lhsv is the liquid hourly space velocity expressed as the ratio of the flow of feed to the volume of catalyst with the unit of hr -1 . and equation (3) for second order : [1/h2sout -1/h2sin] = k /lhsv …(3) with k, the second order rate constant expressed in gm -1 l hr -1 . tables (2-3) show that the concentration of h2s in the gas increased with increasing the flow rate and the lhsv and this is due to the decrease in the contact time between the catalyst particles and the reacting gas, whereas table (4) indicated that the temperature increasing resulted to a reasonable decreasing in the concentration of the h2s and this is a usual phenomenon as the reaction is enhanced at high temperatures. these relations were shown in figures (2-4). table 2 the effect of flow rate on the h2s content, gm/l in the gas leaving the adsorption unit at different temperatures with h2sin as 0.15 gm/l. flow rate, ml/min 553k 573k 593k 613k 0.25 0.0335 0.0253 0.0205 0.0154 0.375 0.0552 0.0455 0.0395 0.0326 0.500 0.0709 0.0615 0.0555 0.0481 0.625 0.0825 0.0735 0.0677 0.0603 table 3 the effect of lhsv on the h2s content at different temperatures with h2sin as 0.15 gm/l and catalyst volume of 15 ml.. lhsv, hr-1 553k 573k 593k 613k 1 0.0335 0.0253 0.0205 0.0154 1.5 0.0552 0.0455 0.0395 0.0326 2 0.0709 0.0615 0.0555 0.0481 2.5 0.0825 0.0735 0.0677 0.0603 table 4 the effect of temperature on the h2s content at different lhsv with h2sin as 0.15 gm/l. temperature, k 1 hr -1 1.5 hr -1 2 hr -1 2.5 hr -1 553 0.0335 0.0552 0.0709 0.0825 573 0.0253 0.0455 0.0615 0.0735 593 0.0205 0.0395 0.0555 0.0677 613 0.0154 0.0326 0.0481 0.0603 0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 flow rate, (l/h) h 2 s c o n te n t, ( g m /l ) 553k 573k 593k 613k fig. 2. the effect of flow rate on the h2s content at different temperatures. karim h. hassan al-khwarizmi engineering journal, vol. 4, no. 3, pp 74-84 (2008) 79 0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0 0.5 1 1.5 2 2.5 3 space velocity, (h -1 ) h 2 s c o n te n t, ( g m /l ) 553k 573k 593k 613k fig. 3. the effect of space velocity on the h2s content at different temperatures. fig. 4. the effect of temperature on the h2s content at different space velocities. to test the order of the reaction and hence calculate the thermodynamic parameters, the data in tables (5) and (6) extracted from tables (2-4) were fitted in equations (2) and (3) to give the figures (5) and (6) respectively. 0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.1 550 560 570 580 590 600 610 620 temperature, ( o k) h 2 s c o n te n t, ( g m /l ) 553k 573k 593k 613k 2 h-1 1.5h-1 1 h-1 2.5 h-1 karim h. hassan al-khwarizmi engineering journal, vol. 4, no. 3, pp 74-84 (2008) 80 table 5 the data of ln (h2sin/h2sout) vs 1/lhsv at different temperatures with h2sin as 0.15 gm/l. 1/lhsv, hr 553k 573k 593k 613k 1 1.499 1.781 1.989 2.277 0.67 0.999 1.193 1.333 1.525 0.5 0.749 0.891 0.994 1.139 0.4 0.598 0.712 0.796 0.911 table 6 the data of [1/h2sin-1/h2sout] vs 1/lhsv at different temperatures. 1/lhsv, hr 613k 593k 573k 553k 1 23.184 32.859 42.114 58.268 0.67 11.449 15.311 18.649 24.008 0.5 7.438 9.593 11.351 14.123 0.4 5.454 6.939 8.104 9.917 0 0.5 1 1.5 2 2.5 0 0.2 0.4 0.6 0.8 1 1.2 1/lhsv (h) ln ( h 2 s in /h 2 s o u t ) 553k 573k 593k 613k fig. 5. plot of ln (h2sin/h2sout ) vs 1/lhsv. 0 10 20 30 40 50 60 0 0.2 0.4 0.6 0.8 1 1.2 1/lhsv (h) [ 1 / h 2 s i n 1 /h 2 s o u t ] 553k 573k 593k 613k fig. 6. plot of [1/h2s in -1/h2s out] vs 1/lhsv. karim h. hassan al-khwarizmi engineering journal, vol. 4, no. 3, pp 74-84 (2008) 81 it is clear that figure (5) shows four straight lines that pass through the origin which is consistent with equation (2) while figure (6) show the otherwise as the four curves does not reflect or expressed equation (3) which suppose to give a straight line also. these results are well agree with those of yanxu et.al for h2s removal over znomno bed (9) which proposed the reaction to follow solid diffusion mechanism and those of kim et.al. for kinetic evaluation of h2s biofilteration (22). the slopes of the lines in figure (5) represent the rate constants values of 3216.342, 3307.672, 3374.491 and 3456.459 hr -1 at temperatures of 553, 573, 593, and 613k respectively and is given in table (7). table 7 the effect of temperature on the first order rate constant, k obtained from equation (1). temperature, k 1/t k, lnk ln(k/t) 553 0.00181 1.499 0.405 -5.911 573 0.00174 1.781 0.577 -5.774 593 0.00169 1.989 0.688 -5.697 613 0.00163 2.277 0.823 -5.595 the arrhenius equation that satisfies the relationship between the rate constant and the reaction temperature k=aoexp(-ea/rt) …(4) with the ea, the activation energy of the reaction, r is gas constant and ao is the pre-exponential factor. so, by plotting the ln k values against the 1/t as shown in figure (7), the slope is (-ea/r) from which the activation energy was calculated to be 19.26 kj/mole. 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.6 1.65 1.7 1.75 1.8 1.85 1000/t, ( k -1 ) ln k fig. 7. plot of lnk vs 1/t. karim h. hassan al-khwarizmi engineering journal, vol. 4, no. 3, pp 74-84 (2008) 82 5 5.5 6 1.6 1.65 1.7 1.75 1.8 1.85 1000/t, ( k -1 ) ln k /t fig. 8. plot of ln (k/t) vs 1/t. 8. thermodynamics of the hydrogen sulfide removal over zno catalysts to calculate the enthalpy h and entropy s of activation the following equation which was obtained from the absolute rate theory was used. k/t= kt .(f/h). exp(s/r) exp(-h/rt) ...(5) where kt is the transmission coefficient and is taken to be equal to 1, h is the planck constant and f is the boltzmann constant and r is the universal gas constant. so a plot of ln(k/t) vs 1/t was a straight line and shown in figure (8) which gives a slope of -h/r from which activation enthalpy was calculated to be 14.49 kj/mole. the intercept of this line which is equal to [(kt .f)/h] + [(s/r] was used to calculate activation entropy s value of -220.41 j/mole.k. conclusions the chemical method for the combined preparation of pure zno and the catalyst was revealed that it is very simple, controllable, and not need sophisticated equipments compared to the thermal method which is solely limited for the preparation of pure zno. catalyst characterizations indicated very good similarities between the prepared and commercial catalyst and this was reflected upon the performance of the catalysts when tested in a laboratory performance unit and indicated that the catalyst can be operated with more than 99% efficiency. kinetic study indicated that the hydrogen sulfide removal over zinc oxide catalyst follows first order reaction with activation energy of be 19.26 kj/mole and enthalpy and entropy of activation of 14.49 kj/mole and -220.41 j/mole.k respectively. references [1] g.p hobson, “modern petroleum technology” 4 th ed., applied science publisher ltd, great britain (1975). 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[22] k.d. jones, a. martinez, k.maroo, s.deshpande and j.boswell, journal of the air and waste management association, january (2004). http://www.sciencedirect.com/science/journal/00092509 http://www.sciencedirect.com/science?_ob=publicationurl&_tockey=%23toc%235229%232003%23999419989%23421731%23fla%23&_cdi=5229&_pubtype=j&_auth=y&_acct=c000050221&_version=1&_urlversion=0&_userid=10&md5=9c2c538a381d7d13ceb71deafa9798a1 http://www.sciencedirect.com/science?_ob=publicationurl&_tockey=%23toc%235229%232003%23999419989%23421731%23fla%23&_cdi=5229&_pubtype=j&_auth=y&_acct=c000050221&_version=1&_urlversion=0&_userid=10&md5=9c2c538a381d7d13ceb71deafa9798a1 http://www.sciencedirect.com/science?_ob=publicationurl&_tockey=%23toc%235229%232003%23999419989%23421731%23fla%23&_cdi=5229&_pubtype=j&_auth=y&_acct=c000050221&_version=1&_urlversion=0&_userid=10&md5=9c2c538a381d7d13ceb71deafa9798a1 http://www.sciencedirect.com/science/journal/00162361 http://www.sciencedirect.com/science?_ob=publicationurl&_tockey=%23toc%235726%232002%23999189998%23275613%23fla%23&_cdi=5726&_pubtype=j&_auth=y&_acct=c000050221&_version=1&_urlversion=0&_userid=10&md5=1be0ef2ef529cab060726a96930f2560 http://www.sciencedirect.com/science?_ob=publicationurl&_tockey=%23toc%235726%232002%23999189998%23275613%23fla%23&_cdi=5726&_pubtype=j&_auth=y&_acct=c000050221&_version=1&_urlversion=0&_userid=10&md5=1be0ef2ef529cab060726a96930f2560 http://www.sciencedirect.com/science?_ob=publicationurl&_tockey=%23toc%235726%232002%23999189998%23275613%23fla%23&_cdi=5726&_pubtype=j&_auth=y&_acct=c000050221&_version=1&_urlversion=0&_userid=10&md5=1be0ef2ef529cab060726a96930f2560 http://www.sciencedirect.com/science/journal/09205861 http://www.sciencedirect.com/science?_ob=publicationurl&_tockey=%23toc%235226%232006%23998839995%23630524%23fla%23&_cdi=5226&_pubtype=j&_auth=y&_acct=c000050221&_version=1&_urlversion=0&_userid=10&md5=209a62b07c3137d1191c7a8f1660bcff karim h. hassan al-khwarizmi engineering journal, vol. 4, no. 3, pp 74-84 (2008) 84 تحضير العامل المساعذ اوكسيذ السنك المستخذم الزالة كبريتيذ الهيذروجين، فحص الفعالية ودراسة الحركية ** اميل محمذ رحمن* زهير عبذ االمير خماش * كريم هنيكش جايعت دٚانٗ / كهٛت انعهٕو/ قسى انكًٛٛاء* جايعت بغذاد / كهٛت ُْذست انخٕارسيٙ/ قسى ُْذست انكًٛٛاء االحٛائٛت** الخالصة جزٖ ححضٛز انعايم انًساعذ أٔكسٛذ انخارطٍٛ انًسخخذو فٙ إسانت كبزٚخٛذ انٓٛذرٔجٍٛ يٍ انغاس انطبٛعٙ كًٛٛأٚا بطزٚقت انخزسٛب كًا جزٖ فحض فعانٛت انعايم . حى إجزاء اخخبار انخٕاص انفٛشٚائٛت ٔانكًٛٛائٛت نٓذِ انًادة . 7ربَٕاث انخارطٍٛ عُذ انذانت انحايضٛت انبٛك األٔنٗ، نخٕنٛذ غاس كبزٚخٛذ انٓٛذرٔجٍٛ يٍ إسانت . انًساعذ اليخظاص كبزٚخٛذ انٓٛذرٔجٍٛ باسخعًال يُظٕيت رٚادٚت حخكٌٕ يٍ ٔحذحٍٛ . أيا انثاَٛت، اليخظاص كبزٚخٛذ انٓٛذرٔجٍٛ يٍ قبم انعايم انًساعذ انًحضز. انكبزٚج بانٓٛذرٔجٍٛ نهُفثا أشارث يقارَت انفحض بٍٛ انعايم انًساعذ انًحضز ٔانخجار٘ إنٗ إيكاَٛت االعخًاد عهٗ انطزٚقت انكًٛٛائٛت كخذبٛز نخحضٛز انعايم . انًساعذ ٔبكفاءة عانٛت جذا ٔأٌ أَثانبٛت ٔأَخزٔبٛت انخُشٛط يٕل/ كٛهٕجٕل19.26أظٓزث دراست حزكٛت انخفاعم أَّ ٚخبع حزكٛت انًزحبت األٔنٗ بطاقت حُشٛط يقذارْا . ٔعهٗ انخٕانٙدرجت كهفٍ. يٕل/كٛهٕجٕل 220.41 ٔيٕل/كٛهٕجٕل 14.49نهخفاعم ْٙ (microsoft word 108-123\335\321\307\323 \346\307\343\344\355\311) al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 15, no. 2, june , (2019) p.p. 108123 heuristic d* algorithm based on particle swarm optimization for path planning of two-link robot arm in dynamic environment firas a. raheem * umniah i. hameed** *,**department of control and systems engineering/ university of technology *email: 60124@uotechnology.edu.iq **email: 61126@uotechnology.edu.iq (received 29 november 2018; accepted 14 january 2019) https://doi.org/10.22153/kej.2019.01.004 abstract finding a path solution in a dynamic environment represents a challenge for the robotics researchers, furthermore, it is the main issue for autonomous robots and manipulators since nowadays the world is looking forward to this challenge. the collision free path for robot in an environment with moving obstacles such as different objects, humans, animals or other robots is considered as an actual problem that needs to be solved. in addition, the local minima and sharp edges are the most common problems in all path planning algorithms. the main objective of this work is to overcome these problems by demonstrating the robot path planning and obstacle avoidance using d star (d*) algorithm based on particle swarm optimization (pso) technique. moreover, this work focuses on computational part of motion planning in completely changing dynamic environment at every motion sample domains. since the environment type that discussed here is a known dynamic environment, the solution approach can be off-line. the main advantage of the off-line planning is that a global optimal path solution is always obtained, which is able to overcome all the difficulties caused by the dynamic behavior of the obstacles. a mixing approach of robot path planning using the heuristic method d* algorithm based on optimization technique is used. the heuristic d* method is chosen for finding the shortest path. furthermore, to insure the path length optimality and for enhancing the final path, pso technique has been utilized. the robot type has been used here is the two-link robot arm which represents a more difficult case than the mobile robot. simulation results are given to show the effectiveness of the proposed method which clearly shows a completely safe and short path. keywords: d* algorithm, known dynamic environment, particle swarm optimization, path planning, two-link arm. 1. introduction the words “path planning” in robotics where the process is totally or sub automated. it is used to refer to this type of computational process for moving an object from one place to another with respect to obstacles. in other word it is searching for initial feasible path and this is the first step in the planning process for the robot path. the path planning problem is that of finding a path for a robot that must move from initial point, which is given as the start position to the goal point which is given as the destination position, in an environment that contains a fully defined set of obstacles. therefore, the robot does not collide with any of the obstacles [1]. generally, obstacles cannot always be static. when the object stays motionless in the environment, it calls static, i.e., fixed constantly at a location, but when the object changes its location over time, it calls dynamic. dynamic environment represents a revolution and important side in modern automation, it redound in many important diverse applications like, air and sea firas a. raheem al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 108123 (2019) 109 traffic control negotiating, freeway traffic, intelligent vehicles, automated assembly and automated wheel chairs. because of existence the moving objects, the robot needs to make decision quickly for avoiding possibility collisions. this represents the mutual part among these applications. the ability to deal with moving objects is needful for the navigation of any factual robot. the range of applications of intelligent robots could be widely increased since it’s able to handle moving objects [2-3]. there are three types of dynamic environment, where all information is regarding to the obstacles, i.e., motions, sizes, shapes, locations, etc., is completely known, the obstacle is said to be in a known dynamic environment. as example for known environment the automated production line. partially known dynamic environment is the second type when not the all information about the obstacle are exist at the planning time. in this state, it needs to calculate the robot motion with according to insufficient information about the environment. it is important to know when the robot's mission is to complete a map of the environment by scanning the area or to scan a certain area to make sure if there is a new object is found in the area. finally when there is nothing to know about the obstacle it’s called the totally unknown dynamic environment and this need intelligent ways to be used. as example for unknown and partially known environment the other robots and humans in workspace [3]. path planning in dynamic environment is considered as an essential problem for manipulators and autonomous robots therefore, the fundamental issue of this work is to show the robot path planning in a dynamic environment and moving obstacle avoidance utilizing d* algorithm to fulfill the accompanying necessities. 2. review of previous researches to overcome the dynamic environment challenges, many path planning algorithms have been used in the literature. here we started with anthony stentz [4] whom used the d* algorithm which is represented the dynamic a*, it aims to create a short path in real-time by incrementally reforming paths for the robot’s state as a new information is found. the d* extension which concentrate the repairs of significantly reduction the whole time required to subsequent and calculate the initial path re-planning operations which this paper aims to. followed by enric cervera i mateu [5] who suggested using robot programming architecture to learn fine motion tasks such as autonomous process of experience repetition could carry out the goal in minimized steps. this involves uncertainty in location, and the robot will be guided with sensory information by using force sensor but this work involves uncertainty in location. many other path planning algorithms were applied for solving dynamic environment problems such as deriving the non-linear vobstacle for general planar obstacles to be useful in analytic expressions. considering obstacles moving on arbitrarily trajectories is represents the concept of counting velocity obstacles. the nonlinear v-obstacle has been consisted of a deformed cone i.e. a time-scaled map of the obstacles that extend along their trajectories. avoiding the obstacle during the time interval for which the v-obstacle has been generated could be achieved by selecting a single velocity vector outside the nonlinear v-obstacle. this method works accurate only with mobile robot [6]. as well as this, finding out a reasonable relation among parameters that used in the path planning strategies in a platform, where a robot will be able to move freely from the start location in a dynamic environment with map and make an optimal path to a set target location without collision with the static and moving objects. researchers used a new optimal type algorithm of rapidly-exploring random tree rrt algorithm, named rrt*. the mechanism of this strategy is based on incremental sampling that covers the all space and will act quickly. it can be used in more than single dimension environments and will be computationally efficient but they have found that a high number of sampling doesn’t give the best solution in addition to the higher computational time that was required for finding the path [7]. from a point of view, algorithm for specify cartesian constraints in a single and dual arm operation is proposed and became a library for solving manipulator motion planning problems that has been developed. the main algorithm is based on rrt. one parameter is used to be the common in all rrt based on planers is the range. the range represents a threshold for the samples drawn newly and their small distance values after that those will add to the tree. range value will be affective on the planning time which means that it should be selected carefully since the higher values causing short time planning which is advantage but as a result it also cause a tensive motions and the smaller values give a long time planning and it composed more points in the tree. also more checking will be needed for the firas a. raheem al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 108123 (2019) 110 collision that may be occur in the space, therefore it needs extra collision checking [8]. most of the existing literature in dynamic environment considers only the traditional path planning algorithms and there are only a few studies that consider the heuristic algorithms like anirudh vemula [9] whom uses a heuristic based graph search planning algorithm that uses adaptive dimensionality consider time dimension corresponding to region where potential dynamic obstacle collisions can occur. this reduction in search space supply the approach in great speedups in planning time over traditional approaches such as heuristic-based a*, will act without losing safety, dynamic feasibility and bounded suboptimality of the solution this approach can only model simple interactions and fail to generalize for complex crowded settings. inspired by the above discussion, the contribution of the proposed method in this paper can be summarized in the following points: • finding path solution utilizing the heuristic d* algorithm based on the pso optimization technique in known dynamic environment. • applying the proposed method using two-link robot arm, which does not used before. • this work can solve the problem of finding an optimal path in dangerous, harsh, toxic environments and inaccessible areas. 3. two-link robot arm kinematics kinematics is the science of motion that treats the subject without regard to the forces that cause it. two types of kinematics problems can be classified, the first one is the forward kinematics problem which is concerned with the relationship between the individual joints of the robot manipulator and the position and orientation of the tool or end-effector [10]. the second is the inverse kinematics problem of the serial manipulators has been studied for many decades. it is needed in the control of manipulators. solving the inverse kinematics is computationally expensive and generally takes a very long time in the real-time control of manipulators. tasks to be performed by a manipulator are in the cartesian space, whereas actuators work in joint space. cartesian space includes orientation matrix and a position vector. however, joint space is represented by joint angles. the conversion of the position and orientation of a manipulator endeffector from cartesian space to joint space is called an inverse kinematics problem [11]. the planar manipulator is shown in figure (1) to illustrate the 2-dof. the planar manipulators have � �and � � as their link lengths and � � and � � represent joint angles with x and y as task coordinates. fig. 1. two degrees of freedom manipulator. the forward kinematics equations are shown below: � � � � cos �� �� � cos��� � ��� … (1) � � � � sin �� �� � sin��� � ��� … (2) in 2-dof planner manipulator, the geometric solution approach of inverse kinematics is used for obtaining the joint variables for all the points in cartesian space regardless their orientation. the calculations of �� and �� for the 2-dof manipulator could be found by applying the following equations. utilizing the cosines law, where the angle is given by: cos �� � �� ���� � !" � !� � �!"!� � # … (3) since sin �� is sin �� � √1 & #� � … (4) to solve �� , it has to use the '() �function. although it is more benefical to use *+, �for numerical solution [11]. subsequently, the two conceivable solutions for �� can be written as: �� � tan � √� -� . / … (5) at last, ��can be solved by: �� � tan �0� �1 2 & tan � !� 345 6� !"�!� 783 6� … (6) where ��and �� are lengths of of the first and the second links, respectively. 4. free cartesian space analysis the result of inverse kinematics has been used to build and analyze the workspace in this work. the specific points that the end-effector can reach, firas a. raheem al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 108123 (2019) 111 can be defined as free cartesian space (fcs). the angles (�� and ��) which were found by inverse kinematics are related to these specific points directly. the shape and volume of the fcs in an environment, which contains many obstacles, are changed depending on the number of obstacles, position and size in addition to the joints limits. in order to model and simulate the motion of twolink robot arm according to plan the path, the theoretical range of the two-link arm shown in table (1). these restrictions impact and limit movement of manipulator and additionally split up the workspace into a reachable region and an inaccessible one. table 1, the theoretical range of the two-link robot arm link no. ranges joint 1 0 ≤ �� ≤ 360 joint 2 -90 ≤ �� ≤ 90 to find all possible solutions, should be computed the fcs and that was done by analyzing the environment’s points. the center point and the diameter of the obstacles are the basic issues upon which the checking function depend. moreover, there are four possible states for each point in the whole environment. the first state is the elbow up solution, the second state is the elbow down solution and the third state is the elbow up and down solution where the arm could reach the target either in elbow up solution or elbow down solution and as shown in figure (2). in addition, there is the last state the no solution case because the point lies out of the reachable area of the manipulator or on an obstacle, or the one or two links collide with an obstacle [12]. fig. 2. the configurations of two-link arm elbow up and elbow down. the resulted areas are separated into three parts, the first one contain the points which can be reached by the elbow up solution, and the second area contains the points which can be reached by the elbow down solution, and the third one represents the unreachable points that contain points outside the accessible range of manipulator workspace, points in obstacle’s body and points that make collision with the obstacles. the biggest factor that affects the free cartesian is the length of the arm link [12]. 5. heuristic d* algorithm the d* algorithm is an algorithm that is generate short path in real-time by a graph with update or change arc costs. the utility of d* is that the most of arc cost corrections occurs in the robot’s neighborhood. from this corrections, the only part of the path is going to out to the robot’s current location is need for replanting. the partial optimal cost map are keep limited for the locations that the robot may use. furthermore, the states that is probable to produce a new optimal path is used to reform of the map’s cost which will be limited and re-entrant partially. d* sets the conditions for determining when repair will be stood, because of finding a new path or the previous path has been found is still optimal. so, the d* strategy is used to say that it is very memory active, works in unbounded environments and computationally as well. the mechanism of the d* algorithm is designed repeat finding optimal path to the directed graph, which means that the arc costs are assorted with transference cost values that could be ranged over a continuation. the corrections of the arc cost that came from the sensors it could be made in any time, also the estimated and measured arc costs that known is comprised to the environment map. this strategy could be used in any planning representation, including grid cell structures and visibility graphs. [13] f = g+ h … (7) where the f is objective function and g is the estimated cost from start point while ℎ is the cost to the goal. 6. particle swarm optimization technique theory (pso) pso is a laborious stochastic optimization technique, it depends on the intelligence and movement of birds swarms. inspired by the behavior of nature social and dynamic motions firas a. raheem al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 108123 (2019) 112 with communications of fish schooling, insects or birds flocking. a number of basic variations have been developed due to improve speed of convergence and quality of solution found by the pso. the principle of pso technique depends on generated specified number of particles in random positions in the specified workspace, also the velocity of those particles is nominated randomly, each particle has a memory that stores all the best position have been visited before, in addition to the fitness in that position which has been improved over time [14-15]. in each iteration of pso technique, the 9():; and <=�:,; ? vectors of particle i is modified in each dimension j in order to lead the particle i toward either the personal best vector (9@=)*:;) or the swarm’s best vector (a@=)*:;) vel4,b c�� � w × vel4,b c � c� × r�,b × 0pbest4b & pos4b2 � c� × r�,b × 0gbest4b & pos4b2 … (8) the position of each particle (bird) is updated by using the new velocity for that particle, according to equation below: pos4b c�� � pos4b c � vel4b c�� … (9) where '� and '� are the cognitive coefficients ('�+'�<=4), and h�,; and h�,; are random real numbers between [0, 1], the inertia weight i controls the particle momentum [16-17]. the value of <=�:; is clamped to the range [<=�jkl, <=�jkl] to reduce the probability of leaving the search space by the particle. if the search space is defined by the bounds [9()jkl, 9()jkl], then the value of <=�jkl is typically set so that <=�jkl � m ∗ 9()jkl, where 0.1 ≤ m ≤ 1.0. [16] a large inertia weight (w) eases the local when its value is large and eases the global search when its value is small. to summarized pso technique in steps it can be consist of just three steps: 1) calculate fitness for all particles. 2) update local and global bests. 3) update velocity and position for all particles. 7. proposed method: d* algorithm based on pso the path planning algorithm which has been used, is the heuristic d* algorithm that depends expansion nodes, in an environment with moving objects. constructing the environment includes putting the map limitation, start and target locations and the obstacles locations and dimensions. after constructing the environment, the algorithm will start its work. the robot firstly stands on the target node and start the initial expand to its 8-connected neighbor. each node will have an initial cost function where the robot will choose the least cost function node to move on and put it in the closed list while the other nodes will go to the open list. taking into consideration the obstacles having a huge cost function and sorting in the closed list from the beginning and the process is completed like that until reaching the start node. when the search is completed the robot will move from the start on the nodes that have been saved in the closed list to the target node (therefore it is called backward searching method) avoiding the obstacles nodes, the current node, and the next step movement node. the velocity of the moving obstacle is constant and the velocity of the mass point is changing over time (ms × qr) and it is calculated by: vs�t� � ts �c� uv×wx … (10) vy�t� � ty�c� uv×wx … (11) where δ� represents the change of distance in x-axis, δ� represents the change of distance in yaxis, ms represents the motion sample and qr represents the sample time which assumed to be 0.01 sec. after finding the d* path, the pso optimization technique is used for enhancing the path, removing sharp edges and making it the shortest because the d* path has stairs shape sometimes. the proposed planning for the mass point in dynamic environment is shown in figurer (3). the first step to operate the pso, is to set the parameters of pso ('�=1, '�=3, w=1) which are found by a trial and error technique to reach the best results. now, the d* path enters the pso work, which will represent the d* path as the search space and choose the optimal points from it, taking into account the general shape for the d* path and without distorting the original form. after determining the pso search space which is the d* path matrix, the search process begins with defining the number of via points (birdsnumber) that search for the new points according to the search space dimension and the pso parameters. these via points are chosen randomly from the search area (d* path) and will represent the position parameters in the pso equation. the cubic spline interpolation equation has been used to connect the bestchosen points from the pso optimization technique to generate corresponding smoothed path. the cost function of pso which is firas a. raheem al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 108123 (2019) 113 the path length is computed. then the elementary velocity is set, and updating the local and global parameters is the next step. the procedure is reiterated until the given points that are looked over the path are finished. the next step is updating the velocity and position equations, for converging the via points into the best cost, and also updating the local and global parameters, the flowchart in figure (4) explains the entire process. the cubic polynomial will connect the start point and goal point through the waypoints that are used for calculating the following cost function, which will be minimized by pso algorithm. the final optimal path length represented in the equation (12) below. cost =∑ \��: & �:���� � ��: & �:����j :]� … (12) fig. 3. proposed planning for the mass point in dynamic environment. fig. 4. the heuristic d* via point flowchart for known obstacle position dynamic environment. 8. simulation results and discussion 8.1 first environment here it is applied the two-link robot arm as a case study. the first and second link length is equal to the half of the robot workspace and the arm has 360 degrees. figure (5), clarifies the environment analysis and the obstacle motion behavior with four moving obstacle two from these obstacles move in a square motion shape, for a while, this generated path looks like a little bit simple, but this environment featured a critical path, as shown in figure (6), where figure (6.a) represents the elbow down analysis, figure (6.b) represents the elbow up analysis and figure (6.c) represents the elbow up and down analysis. in fcs analysis figures the colored area (blue, red or green) indicates the free and safe area for moving robot links while the white area indicates the unreachable area. therefore, the robot can take a proper decision for selecting the next points in a free and completely safe path inside the permitted motion area. since the fcs is very limited because of the range of obstacle’s motion, so the robot will move in elbow down free space as mentioned in figure (2) to the configuration of the two-link arm elbows. figure (7) shows the twolink robot arm environment which looks very crowded for moving in. where the process is offline, the pso optimization technique is used to get rid of sharp edge and shorten the path and as shown in figure (8), the d* path based on pso was decreased by 3.2846 cm long from the original path as shown in table (2), which clarify the environment information such as the original d* path length and the new optimal path length which is clearly shorter. figure (9) represents the new path of d* based on pso. the joint angles and change in angles based on pso path are shown in figure (10) and (11) respectively. fig. 5. obstacle motion behavior. firas a. raheem al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 108123 (2019) 114 (a) (b) (c) fig. 6. fcs for known obstacle position dynamic environment where (a) represents elbow down, (b) represents elbow up and (c) represents the gathering between elbow up and elbow down. firas a. raheem al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 108123 (2019) 115 fig. 7. the two-link robot arm result for the d* path. (a) (b) fig. 8. (a) represents final d* and (b) represents pso path and the path cost function. 0 50 100 150 200 250 300 58.8 58.9 59 59.1 59.2 59.3 59.4 59.5 iteration b e s t c o s t firas a. raheem al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 108123 (2019) 116 fig. 9. the two-link robot arm result for the d* based on pso path. fig. 10. the first and second angles of the two-link robot arm result for the d* path. firas a. raheem al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 108123 (2019) 117 fig. 11. the change in first and second angles of the two-link robot arm result for the d* path. 8.2 second environment for more verification, a second more complicated environment with six moving obstacles in such different way in comparing with the first environment and more close to the robot links. figure (5), also could clarify the environment analysis since this environment has only horizontal and vertical motion styles. this environment featured planning in complex workspace and generate path in narrow area, as shown in figure (12) where figure (12.a) represents the elbow down analysis, figure (12.b) represents the elbow up analysis and figure (12.c) represents the elbow up and down analysis, in fcs analysis figure the colored area (blue, red or green) indicates the free and safe area for moving robot links while the white area indicates the unreachable area. therefore, the robot can take a proper decision for selecting the next points in a free and completely safe path inside the permitted motion area. since the fcs is very limited because of the range of obstacle’s motion, so the robot will move in elbow up free space as mentioned in figure (2) to the configuration of the two-link arm elbows. figure (13) shows the twolink robot arm environment which looks very crowded for moving in. where the process is offline, the pso optimization technique is used to get rid of sharp edge and shorten the path and as shown in figure (14), the d* path based on pso was decreased by 2.4413 cm long from the original path as shown in table (2), which clarify the environment information such as the original d* path length and the new optimal path length which is clearly shorter. figure (15) represents the new path of d* based on pso. the joint angles and change in angles based on pso path are shown in figure (16) and (17) respectively. (a) (b) firas a. raheem al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 108123 (2019) 118 (c) fig. 12. fcs for known obstacle position dynamic environment where (a) represents elbow down, (b) represents elbow up and (c) represents the gathering between elbow up and elbow down. firas a. raheem al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 108123 (2019) 119 fig. 13. the two-link robot arm result for the d* path for the second environment (a) (b) fig. 14. (a) represents final d* and (b) represents pso path and the path cost function for the second environment. 0 10 20 30 40 50 60 70 80 90 100 64.1 64.15 64.2 64.25 64.3 64.35 iteration b e s t c o s t firas a. raheem al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 108123 (2019) 120 fig. 15. the two-link robot arm result for the d* based on pso path for the second environment. fig. 16. the first and second angles of the two-link robot arm result for the d* based on pso path for the second environment. firas a. raheem al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 108123 (2019) 121 fig. 17. the change in first and second angles of the two-link robot arm result for the d* based on pso path for the second environment. at first, the d* algorithm is applied to find the shortest and best path then the particle swarm optimization method is used to enhance the final path by removing the sharp edges as clearly shown in results figures of the first and the second environment till finding optimal path. the result clearly proves the advantage of using the proposed mixed approach as shown in table (2). in comparison with other path planning algorithms like artificial potential field (apf) [2, 17], the heuristic d* is more suitable for the dynamic environment because of its behavior in saving cost and gives safe and better path length cost function. in addition, the most important issue is the heuristic methods does not suffer from the local minima problem that appears mainly in apf path planning approaches. table 2, environments information. environment 1 2 obstacles number 4 6 population 50 50 iteration 300 100 d* path 62.1421 cm 66.5685 cm pso path 58.8575 cm 64.1272 cm 9. conclusions this paper proposed a methodology that considers solving the path planning problem for two-link robot arm in known position changes dynamic environment utilizing the use of heuristic d* algorithm for finding the best path and the use of pso optimization technique for getting the final optimal path. from this approach, it was possible to get an acceptable path in spite of the environment difficulties where a completely collision free path could be found at the expense of optimality. therefore, the pso optimization technique has been used to reach optimality. the length of the new path produced by the optimization technique was smooth, safe, optimal and shortest which traditional d* method could not find such a path. 10. references [1] h. miao, y.-c. tian and y.m. feng, “robot path planning in dynamic environments using a simulated annealing based approach”, faculty of science and technology queensland university of technology, 2014. [2] f. a. raheem and m. m. bader, “development of modified path planning algorithm using artificial potential field ( apf) based on pso for factors optimization,” american scientific research journal for engineering, technology, and science, 37, 316-328, 2017. [3] kikuo fujimura, “motion planning in dynamic environments”, springer-verlag tokyo, 1991. https://doi.org/10.1007/978-4431-68165-6 [4] a. stentz, the focused d* algorithm for real-time replanning. proceedings of the international joint conference on artificial intelligence, montreal, 20-25 august 1995, 1652-1659, 1995. [5] enric cervera i mateu, “perception –based learning for fine motin planning in robot manipulation”,jaume-i university of castello. spain, 1997. [6] z. shiller, f. large and s. sekhavat, “motion planning in dynamic environments: obstacles moving along arbitrary trajectories”, mechanical and aerospace engineering, university of california, proceedings of the ieee international conference on robotics & automation seoul, korea. may 21-26, 2001. [7] r. s. m. asghari and o. a. tabataba , “mobile robot path planning by rrt* in dynamic environments”, mecs, april 2015. [8] b. asadi, “single and dual arm manipulator motion planning library”, ieee/rsj international conference on intelligent robots and systems (iros), hamburg, 28 september-2 october 2015. firas a. raheem al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 108123 (2019) 122 [9] a. vemula, “safe and efficient navigation in dynamic environments,” carnegie mellon university, pittsburgh, no. july, 2017 [10] mark w. spong, seth hutchinson, m. vidyasagar “robot modeling and control” united states of america first edition, wiley, hoboken, 2006. [11] john j. craig “introduction to robotics mechanics and control” united states of america third edition, pearson prentice hall pearson education, inc., upper saddle river, nj. 2005. [12] a. t. sadiq, f. a. raheem, and n. a. f. abbas, “optimal trajectory planning of 2dof robot arm using the integration of pso based on d * algorithm and cubic polynomial equation,” first int. conf. eng. res., no. march, pp. 458–467,2017. [13] a. t. sadiq, f. a. raheem, and n. a. f. abbas, “robot arm path planning using modified particle swarm optimization based on d * algorithm” al-khwarizmi engineering journal, vol. 13, no. 3, pp. 2737, 2017. [14] p. boonyaritdachochai, et al., "optimal congestion management in an electricity market using particle swarm optimization with time-varying acceleration coefficients," computers & mathematics with applications, vol. in press, corrected proof, 2010. [15] poli, r., kennedy, j. and blackwell, t. particle swarm optimization: an overview. swarm intelligence, 1, 33-57, 2007 [16] k. t. chaturvedi, et al., "particle swarm optimization with time varying acceleration coefficients for non-convex economic power dispatch," international journal of electrical power & energy systems, vol. 31, pp. 249257, 2009. [17] ni, j.j., wu, w.b., shen, j.r. and fan, x.n. an improved vff approach for robot path planning in unknown and dynamic environments. mathematical problems in engineering, 2014, article id:461237. https://doi.org/10.1155/2014/461237 )2019( 108123، صفحة 2د، العد15دالخوارزمي الهندسية المجلجلة م امنية ابراهيم حميد 123 باالعتماد على تقنية d*ستخدام خوارزمية اتخطيط مسار لذراع روبوت ب سرب الطيور رحيم* عبد الرزاقفراس حميد** ابراهيمأُمنية العراق / بغداد /الجامعة التكنولوجية /قسم هندسة السيطرة والنظم ،*** 60124@uotechnology.edu.iq :البريدااللكتروني 61126@uotechnology.edu.iq :البريدااللكتروني الخالصة ذلك فأنها تمثل القضية الرئيسية للروبوتات واذرع الروبوتات فضالً عنان ايجاد حل للمسار في بيئة ديناميكية يمثل تحديا للباحثين في مجال الروبوتات مثل الكائنات المختلفة والبشر والحيوانات أو روبوتات أخرى المسار الخالي من التصادم في البيئات ذات العوائق المتحركة دالتي يتطلع اليها العالم اليوم. يع األكثر شيوًعا في جميع خوارزميات تخطيط المسار. كالتذلك، الحدود الدنيا المحلية والحواف الحادة هي المش فضالً عنمشكلة حقيقية ويحتاج إلى حل. عالوة على ، psoباالعتماد على تقنية التحسين *dستخدام خوارزمية تخطيط المسار اب شكالتالرئيس من هذا العمل هو التغلب على هذه الم الهدف نظًرا ألن نوع البيئة الذي تمت . motion sample، يركز هذا العمل على الجزء الحسابي من تخطيط الحركة في بيئة ديناميكية متغيرة تماًما مع كل ذلك هو دائما الحصول على حل المسار off-line ـ. ان الميزة الرئيسة لتخطيط المسار الoff-lineمناقشته هنا هو البيئة الديناميكية المعروفة فأن الحل سيكون مع *dالديناميكي للعقبات. ولذلك تم اللجوء الى خوارومية ، والتي هي قادرة على التغلب على جميع الصعوبات الناجمة عن السلوك االمثل. global ال لتحسين psoللحصول على اقصر مسار ومن ثم تطبيق تقنية تحسين المسار *dحيث تم استخدام خوارزمية تخطيط المسار psoتقنية التحسين ال ية الختبار الطريقة المقترحة وهي تمثل حالة اكثر صعوبة من الحالة دراسبوصفه المسار النهائي. تم استخدام ذراع الروبوت ثنائي درجات الحرية mobile robot بوضوح المسار االمن والقصير تماما. ررحة والتي تظهقت. كما ان نتائج المحاكاة تظهر فعالية الطريقة الم 124 al-khwarizmi engineering!!! journal al-khwarizmi engineering journal, vol. 7, no. 1, pp 1 12 (2011) biomechanical concept design of artificial human hand sadiq jafer abbass* farah mohammed rudah masoud** * department of medical engineering/ university of al-nahrain ** department of biomedical engineering/!al-khawarizmi collage of engineering/ university of baghdad (received 22 april 2010; accepted 15 november 2010) abstract this work is focused on the design parameters and activity of artificial human finger for seven grips. at first, obtained the ideal kinematics of human fingers motion by analyzing the grips video which were recorded using a single digital camera recorder fitted on a tripod in sagital plane while the hand is moving. special motion analysis software (dartfish) the finger joint angles were studied using the video recording. then the seven grips were modeled using static torque analysis, which calculates the amount of torque applied on the fingers joint grip depending on the results of the kinematic analysis. the last step of the work was to design the actuator (muscle wire) of artificial finger for the seven grips in a simple design approach for artificial finger actuated by (muscle wire). keywords: kinematic analysis, human hand, dartfish, grips, muscle wire. 1. introduction many people lose the use of one of their hands, either through accident or birth defect. although there are many solutions for a missing appendage, there are very few that give the user the same freedom of movement and control as a real hand. robotic hands have been researched for the past four decades, many of which do not give as many degrees of freedom as a human hand [1]. the hand’s functional uniqueness has been recognized and discussed extensively in the literatures. this work attempt to make simple design for the human finger that would facilitate the designing of prosthetic hand, this design depended on the kinematics analysis that calculated by using a special motion analysis program (dartfish), and these results used to evaluate the static torque analysis of the human finger in different grip .the actuator of this finger was muscle wire (shape memory alloy) which designed depending the static torque analysis. the purpose of the study to overcome the shortcomings of conventional prostheses by utilizing a biomimetic (i.e., life-like) approach to prosthetic hand design. this involves attempt to design a biomimetic finger that facilitate in designing a prosthetic hand which give the amputee that loss their hand new chance, calculate the kinematic analysis and the static torque analysis for the human hand in different grips, utilization of the smart materials (shape memory alloy) that work as artificial muscle. the results of this work could be used as standardized values for designing the prosthetic finger by multiplying it with actual force (change from one to another) that acting on the finger during performance the grips. 2. anatomical structure of human hand the basic hand bones consist of the carpals, metacarpals, and phalanges. the carpal bones form the wrist and consist of eight bones arranged in two rows of four. the metacarpals form the palm area of the hand and consist of five long bones that radiate from the carpal bones as shown in fig. (1). finally, the phalanges form the fingers of the hand. there is a proximal phalanx, a middle phalanx, and a distal phalanx for each finger [2]. the human hand has about 34 muscles that control it, which are classified into those outside of the hand (extrinsic muscles) and those that are this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ sadiq jafer abbass al-khwarizmi engineering journal, vol. 7, no. 1, pp 1 12 (2011) 2 within the hand (intrinsic muscles). though the extrinsic muscles are located in the forearm, they transmit their force through tendons attached to the hand [3]. the median and ulnar nerves are the major nerves of the hand, which run the length of the arm in order to transmit electrical impulses to and from the brain to create movement and sensation. the median nerve is mainly responsible for muscles associated with wrist and finger flexion while the ulnar nerve is responsible for the rest of the muscles (all of the intrinsic muscles) in the hand [4]. fig.1. bones of the hand [5]. 3. biomechanics of the hand one may simplify things by thinking of the hand as fifteen joints, each of which is restricted to its own type of movement. these types of movement can be referred to as degrees of freedom as shown in fig.2. the nine interphalangeal joints can be described as only having one degree of freedom: flexion-extension. the five metacarpophalangeal joints, however, have two degree of freedoms: flexion-extension and abduction-adduction (i.e. spreading fingers apart). the thumb is a little bit more complicated, with the base of the thumb having an extra two degree of freedoms when compared to the other fingers. and finally, the wrist itself has six degree of freedoms. using this fifteen joint, one can approximate all of the possible movements of the human hand [6]. fig.2. (a): the bones and joint of human hand (b) the structure of the humanoid hand [7]. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ sadiq jafer abbass al-khwarizmi engineering journal, vol. 7, no. 1, pp 1 12 (2011) 3 4. design of the biomimetic finger (index finger) 4.1. geometric parameters of the finger the dimensions of the index finger (length,breadth,depth and mass) are illustrated in the table(1). table 1, dimensions of the index finger [2]. phalanx length (mm) breadth (mm) depth (mm) mass (g) 28.6 20.0 20.0 42.5 proximal 9.6 17.5 19.0 28.125 middle 4.7 13.84 16.6 22.5 distal 4.2. actuation mechanism a hybrid actuation mechanism is proposed where the metacarpaphalengial and phalengialinterpha joints are tendon-driven (muscle wire) and the distalinterphalengeal joint is passively connected to the phalengialinterphalengial joint by a pulley mechanism. the muscle wire formed a special metals undergo changes in shape and hardness when heated or cooled and do so with great force. muscle wires pull with a surprisingly large force (capable of lifting thousands of times their own weight) and move silently with a smooth, life like quality. they can be heated directly with electricity and can be used to create a wide range of motions, operating quickly and with precise controllability [8]. 4.3. kinematic architecture the biomimetic finger consists of three links corresponding to the three phalanges of the human finger. the finger is equipped with three active degrees of freedom two at the metacarba phalengial joint and one at the phalengialinter phalengial joint and a passive degree of freedom at the distalinterphalengial joint. furthermore, these joint center locations remain fixed along the entire range of motion of the phalanges [9]. transposing these features to biomimetic model, fixed axes of rotations were implemented at the head of the phalanges; for the distalinter phalengial and phalengialinterphalengial joints, by modeling them as revolute hinge joints see fig.(3). in these joints, the rotation occurs about a fixed shaft common to the head of the proximal phalanx and the base of middle phalanx for the phalengial interphalengial joint and the head of the middle phalanx and the base of the distal phalanx for the distalinterphalengial joint. the two degrees of freedom articulation of the metacarbaphalengial is modeled using a universal ball joint, which mimics the biaxial nature of the human finger’s metacarbaphalengial joint [2]. fig.3. finger kinematic architecture [2]. fig.4. (shape memory alloy) wire driven agonistantagonist tendon pairs for link i [2]. 4.4. finger kinematics a kinematic analysis of the finger is carried out in order to determine the relationship between the angular position of each joint and the required muscle wire contraction/elongation. the finger was modeled as a robot fixed to the palm. to evaluate the angles of each joint of finger at the seven grips, digital camera was used to perform this function and then the angles for each phalanx are calculated using special motion analysis program (dartfish). if the contracting muscle wire that causes clockwise rotation (flexion) is denoted as wire 1 and the opposing sma wire is referred as wire 2, as shown in fig.(4), then, at actuation, the lengths and of wires 1 and 2 are related to the joint angle i by the following equations [2]: this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ sadiq jafer abbass al-khwarizmi engineering journal, vol. 7, no. 1, pp 1 12 (2011) 4  ioiioi rll   22 …(1)  ioiioi rll   11 …(2) where i : angle of joint i 4.5. mathematical model of hand grips the model is a representation that could be understood, even though such representations may require gross simplifications and assumptions. by comparing a model's behavior with the actual behavior of the system, will obtain further insight in to how components of the system function and are coordinated to achieve desired outcomes. each time a model doesn't predict a system's behavior correctly, could rationally change certain parts of the model, thus gaining insight into the complex nature of the real system, and the human biomechanical system is very complex [10]. one major consideration in designing prosthetic hands is the ability to hold an object in a stable grasp. the joints torques that is sufficient to sustain such a grasp is evaluated for different finger configurations [2]. seven grips were studied (cylindrical, lifting box, push button, hook, spherical, tip and key) fig.(5),but cylindrical grip mentioned in details. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ sadiq jafer abbass al-khwarizmi engineering journal, vol. 7, no. 1, pp 1 12 (2011) 5 n3 n1 fig.5. snaps of different six grips. 4.5.1. cylindrical grip the cylindrical grip fig.(6) was chosen because of its vitality to a wide range of people, especially for the working class in order to enhance their performance and facilitate their daily life. this grip recorded as frames (shots) by the digital camera, then several photos were chosen so as to measure the change in joints angles, the time period between successive chosen shots was different depending on the total time for each grip. fig.6. mathematical model of cylindrical grip. 1. distal phalanx (dp) the moments analysis of the distal phalanx for index finger shown in fig.(7). fig.7. free body diagram of distal phalanx of cylindrical grip.   0xf   0cos90cos 123331233   ffn x …(3)   0yf   0sin90sin 3123312333  yffngm  …(4)   0m   0 2 180cos 2 3 3 3123 3 3  m l n l gm  …(5) 2. middle phalanx (mp) the moments analysis of the middle phalanx for index finger shown in fig.(8). fig.8. free body diagram of distal phalanx of cylindrical grip.   0xf   0cos90sin 123331232   ffn x …(6)   0yf 0cossin 231222122  yy ffngmf  …(7)   0m 0sincos 2 cos 2 12231233 23 2 212 2 2     lflf mm l n l gm xy …(8) 3. proximal phalanx (pp) the moments analysis of the proximal phalanx for index finger shown in fig.(9). fig.9. free body diagram of distal phalanx of cylindrical grip. n2 pp mp dp this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ sadiq jafer abbass al-khwarizmi engineering journal, vol. 7, no. 1, pp 1 12 (2011) 6   0xf 0cossin 111211   fffn xx …(9)   0yf 0cossin 2111111  yy ffngmf  …(10)   0m 0 2 cos 2 121 2 11 2 1   nmm l n l gm …(11) 4.6. actuator design (muscle wire) in static analysis, the torque at joint i is given by the following equation: iiiii dfdft 21  …(12) in terms of the stress in the wires and assuming identical wires are uses iii af  …(13) equation (12) can be written as: iiiiiii dadat 21   …(14) the wire cross-sectional area can, therefore, be expressed in terms of the wire stress values:  21    i i i d t a …(15) the chosen maximum low temperature strain for this work is 5%. from the above, the sma wire lengths can be calculated: [2] z l l   …(16) 5. results and discussion 5.1. result of kinematics for cylindrical grip the total time period of this grip was 1.5s with 14 shot. the angles of joints in each shot are illustrated in table (2), the maximum angle θ was 54.5º in metacarba phalengial joint at 1.4 s and the range of motion was (0º to 54.5º) for metacarpaphalengeal joint, (0º to 106.7º) for phalengealinterphalengeal joint and ( 0º to 153º) for distalinterphalengeal joint also the change of angle of all phalanx in this grip was the same for period (0-0.85sec) beyond this point the angle of metacarba phalengial joint would be constant at level 55º,while still increasing to specific point fig.(10). table 2, kinematics of the index finger in cylindrical grip. angle of dip joint (θ3) (degree) angle of pip joint (θ2) (degree) angle of mcp joint (θ1) (degree) time )sec( 0 0 0 0 9.9 11.8 18.8 0.1000 15.1 19.0 22.3 0.3000 20.4 22.9 27.4 0.4000 25.2 25.0 30.4 0.5000 28.9 33.4 33.9 0.6000 34.6 34.2 38.0 0.7000 37.7 41.7 47.6 0.8000 56.8 56.5 51.7 0.9000 74.7 68.0 54.2 1.0000 89.3 78.1 54.2 1.1000 107.6 104.5 54.2 1.2000 130.1 106.2 54.2 1.3000 153.0 106.2 54.2 1.4000 this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ sadiq jafer abbass al-khwarizmi engineering journal, vol. 7, no. 1, pp 1 12 (2011) 7 fig.10. snaps of cylindrical grip for time from 0 to 1.4 s. 5.2. results of static moment analysis for cylindrical grip in this grip an object with a cylindrical shape is assumed to be pulled. the object is supposed to affect on (distalinterphalingial) and (phalingealinterphalingial) joints, the reaction of this object assumed to be (unit force). from the fig.(11) can be noticed that moment values are between (-0.00667 – 0.0668) nm, and the maximum value was in the metacarpaphalingial joint at 0.5 s. figures (11(a)) through (17(a)) illustrate the relationship between the joints angles and time while the figs.(11(b)) through (17(b)) illustrate the relationship between moment and time for the distalinterphalengeal joint, phalengealinter phalengeal joint and metacarpaphalengeal joint for the seven grips. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ sadiq jafer abbass al-khwarizmi engineering journal, vol. 7, no. 1, pp 1 12 (2011) 8 fig.11. cylindrical grip. !! fig.12. box grip. fig.13. push grip. (a) (b) (a) (b) (a) (b) this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ sadiq jafer abbass al-khwarizmi engineering journal, vol. 7, no. 1, pp 1 12 (2011) 9 fig.14. spherical grip. fig.15. hook grip. fig.16. key grip. (a) (b) (a) (b) (a) (b) this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ sadiq jafer abbass al-khwarizmi engineering journal, vol. 7, no. 1, pp 1 12 (2011) 10 fig.17. tip grip. 5.3. results of muscle wire design (sma) the muscle wire actuator design calculations require the maximum tensile stress at high temperature and the strain of the muscle wire at low temperature to be specified. to ensure that the maximum muscle wire fatigue life is obtained, a typical high temperature tensile stress of 170 mpa is used for ni-ti alloys. furthermore, the recommended bias force that should be applied to extend a cooled muscle wire is 35 mpa [2]. consider the maximum moments that can occur at each joint then by applying the equations (12 to 16) founded the result that mentioned in table (3). table 3, length, diameter, actuation forces for (sma) wire one and two. joint muscle wire length (mm) muscle wire diameter (µm) wire1 force (n) wire2 force (n) mcp 86.95 752.2 300.0 62.19 pip 144.6 486.9 126.6 26.04 since high bandwidths are required, the actuation force can be distributed in to multiple muscle wire of smaller diameter and acting in parallel, therefore the metacarpaphalengeal(mcp) wire1 force (300 n) would distributed in to tow hundred wire of (100 µm), phalengealinterphalengeal (pip) wire 1 force would be forty of (150µm), metacarpa phalengeal wire 2 force would be twenty of (150 µm) and phalengealinterphalengeal wire 2 force would be eighteen of (100 µm). 6. conclusion 1. the video recording method was viable method to obtain kinamatic analysis. 2. dartfish's video management system helped to manage all the movement videos with ease and efficiency during hand moving since it consider each finger segment to be a rigid body, linked to each other by a joint. the software tools are used to get the stick figure representation that helped to find the kinematics. 3. the benefit of this study is to make design for artificial finger that mimics the natural human finger in different grips to be used in the field of rehabilitation and for robotic hand. 4. the muscle wire considered as the actuation system in the design because of its properties that was; low cost, small size, light weight, strong force, and high strength to weight ratio. 5. the human hand is an extraordinary example of how a complex system can be implemented, and how such a system is capable to perform very complex tasks using a combination of different elements. 7. references [1] chao e.y. s., an, k., cooney, w.p. and linscheied,r. "biomechanics of the hand", (a) (b) this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ sadiq jafer abbass al-khwarizmi engineering journal, vol. 7, no. 1, pp 1 12 (2011) 11 teaneck, nj, usa:world scientific publishing co. pte. ltd., 1989, pp (5-75). [2] vishalini b. and edward, "design of an artificial muscle actuated finger towards biomimetic hands", 2005. [3] moore k. l., dally a. f., lippincott william and wilkins, "clinically oriented anatomy",5th edition, 2003. [4] front m., "human physiology", the mc graw-hill companies,2003. [5] seelely –stephens-tate , "anatomy and physiology", six edition, the mc graw-hill companies,2004. [6] rainer palm, "learning of grasp behaviors for an artificial hand by time clustering and takagi-sugeno modeling", 2006 ieee international conference on fuzzy systems sheraton vancouver wall centre hotel, vancouver, bc, canada, july 16-21, 2006. [7] available from the website www.bioeng.nus.edu.sg [8] gilberston, g.," muscle wires project book", 3rd ed., san rafael, ca: mondotronics, 1993. [9] buchholz, b., armstrong, a., and goldstein, s.a., “anthropometric data for describing the kinematics of the human hand”, ergonomics, vol. 35, no. 3, march 1992, pp. 261-273. [10] donb.chaffin,gunnarb.j.andersson,"occupat ional biomechanics",awiley-interscience publication,pp.147-148,1984. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ 12 ، صفحة1العدد ، 7مجلة الخوارزمي الھندسیة المجلد صادق جعفر عباس 1 )2011( 12 االصطناعیة ي للید البشریةحیائاإلمیكانیكي التصمیم مفھوم ال **فرح محمد رضا مسعود *صادق جعفر عباس جامعة النھرین/ قسم الھندسة الطبیة * الھندسة الخوارزمي /قسم ھندسة الطب الحیاتي ** الخالصة القبضة االسطوانیة ، (في سبعة قبضات مختلفھ ) اصبع السبابة(ھذه الدراسھ تتركز حول تصمیم ونمذجة االصبع البشري ).قبضة المفتاح,القبضة الطرفیة , قبضة رفع صندوق ، قبضة الضغط على زر ، قبضة الخطاف ، القبضة الكرویة مظاھر الكینامیتیكیھ المثالیھ الخاصھ بحركة االصبع البشري خالل ھذه تم في ھذه الدراسھ ابتداءا اجراء تصمیم نموذج لل القبضات والتي تم ایجادھا عن طریق تحلیل التصویر الفیدیوي الذي تم تسجیلھ باستخدام كامیرا تصویر فیدیویھ رقمیھ مثبتھ امام لمفاصل ) حركیة(تم دراسة كینماتیكیھ ) dartfish(باستخدام برنامج التحلیل الحركي , المستوى الجانبي اثناء حركة الید البشریھ .االصبع البشري خالل القبضات المختاره من التصویر الفیدیوي الذي یمكننا من حساب مقدار العزم ) تحلیل العزوم االستاتیكي(في المرحلة التالیة تم نمذجة ھذه القبضات عن طریق عمل .د على النتائج المستحصلة من التحلیل الكینماتیكيالمتولد في كل مفصل من مفاصل االصبع باالعتما وع ن ن ا م م اختیارھ ي ت طناعي والت بع االص الخطوة االخیرة في ھذه الدراسة كانت عمل تصمیم لوسیلة التحریك في ھذا االص ).تحلیل العزوم االستاتیكي(باالعتماد على النتائج التي تم استحصالھا من ) االلیاف العضلیة االصطناعیة( this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ óô al-khwarizmi engineering journal al-khwarizmi engineering journal, vol.3, no2, pp 67 -86 (2007) correlation for fitting multicomponent vapor-liquid equilibria data and prediction of azeotropic behavior dr. khalid farhod chasib al-jiboury chemical engineering department university of technology (((rrreeeccceeeiiivvveeeddd 111 ssspppttteeemmmbbbeeerrr 222000000666 ;;; aaacccccceeepppttteeeddd 222444 aaappprrriiilll 222000000777))) abstract correlation equations for expressing the boiling temperature as direct function of liquid composition have been tested successfully and applied for predicting azeotropic behavior of multicomponent mixtures and the kind of azeotrope (minimum, maximum and saddle type) using modified correlation of gibbs-konovalov theorem. also, the binary and ternary azeotropic point have been detected experimentally using graphical determination on the basis of experimental binary and ternary vapor-liquid equilibrium data. in this study, isobaric vapor-liquid equilibrium for two ternary systems: “1-propanol – hexane – benzene” and its binaries “1-propanol – hexane, hexane – benzene and 1-propanol – benzene” and the other ternary system is “toluene – cyclohexane – iso-octane (2,2,4-trimethyl-pentane)” and its binaries “toluene – cyclohexane, cyclohexane – iso-octane and toluene – iso-octane” have been measured at 101.325 kpa. the measurements were made in recirculating equilibrium still with circulation of both the vapor and liquid phases. the ternary system “1-propanol – hexane – benzene” which contains polar compound (1-propanol) and the two binary systems “1-propanol – hexane and 1-propanol – benzene” form a minimum azeotrope, the other ternary system and the other binary systems do not form azeotrope. all the data passed successfully the test for thermodynamic consistency using mcdermott-ellis test method (mcdermott and ellis, 1965). the maximum likelihood principle is developed for the determination of correlations parameters from binary and ternary vapor-liquid experimental data which provides a mathematical and computational guarantee of global optimality in parameters estimation for the case where all the measured variables are subject to errors and the non ideality of both vapor and liquid phases for the experimental data for the ternary and binary systems have been accounted. the agreement between prediction and experimental data is good. the exact value should be determined experimentally by exploring the concentration region indicated by the computed values. keywords: vapor-liquid equilibria, azeotropic behavior, multicomponent system this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. khalid farhod chasib al-jiboury /al-khwarizmi engineering journal ,vol.3, no2 . pp67 –86 (2007) !!óõ introduction the term azeotrope means “nonboiling by any means” (greek: a non, zeo boil, tropos way/mean), and denotes a mixture of two or more components where the equilibrium vapor and liquid compositions are equal at a given pressure and temperature. systems which do not form azeotropes are called zeotropic. departures from raoult’s law frequently manifest themselves in the formation of azeotropes, azeotropes are liquid mixtures exhibiting maximum or minimum boiling points that represent, respectively, negative or positive deviations from raoult’s law. also constantboiling mixtures are referred to as azeotropes. they occur between certain combinations of the components of the mixture or mixtures of closeboiling species of different chemical types. azeotropes occur frequently between compounds whose boiling points differ by less than about 30 oc. if the vapor and liquid are of the same composition, the two-phase mixture is called a homogeneous azeotrope. the constant-boiling mixtures that occur with a vapor and two or more dense phases are called heterogeneous azeotropes (this is because in order to get the liquid to phase separate into two liquid phases the components must be highly repulsive) (hoffman, 1964). the y-x curve crosses the y = x line (the 45o line) at the azeotropic composition, in the region below this intersection with the diagonal, the equilibrium vapor is richer in one component than the liquid, above this intersection, the vapor is poorer in this component than the corresponding liquid from which it comes. for the isobaric system the temperature versus composition curves coincide at a minimum at the azeotropic composition. such azeotropic systems frequently occur when the two components are dissimilar functionally and the boiling points are not greatly different of about 25 oc for most systems, although much greater differences are noted in some systems (mixture in which there is strong repulsion between the different species), because less thermal energy has to be introduced to get molecules to enter the vapor phase to overcome the attraction in the liquid. a high-boiling azeotrope differs from the low-boiling azeotrope in that the temperature versus composition curves of the isobaric plot exhibit maximum, the high-boiling azeotrope is less common than the low-boiling azeotrope, it generally occurs between components whose molecules are somewhat attracted to each other (mixture in which there is strong attraction between the different species), because additional thermal energy has to be introduced to get molecules to enter the vapor phase to overcome the attraction in the liquid. for the t-x-y diagrams if the dew and bubble curves touch at some intermediate composition where the coexisting phases have the same composition. such a point is known as an azeotrope and although the two phases coexist there at the same temperature, pressure and composition, it is distinguished from a critical point by a difference in the density of the phases (harold, 1970). an analysis of the structural properties of vapor-liquid equilibrium (vle) diagrams provides a fundamental understanding of the highly nonideal thermodynamic behavior of azeotropic mixtures. the possibility to graphically represent the vle depends on the number of components in the mixture. phase diagram analysis is an excellent tool for gaining insights into the complex behavior of nonideal ternary mixtures. ternary vapor-liquid equilibrium (vle) diagrams provide a graphical tool to predict qualitatively the feasible separations for multicomponent azeotropic mixtures before detailed simulation or experimental study of their distillation (walas, 1985). the main difference for ternary and multicomponent mixtures is that an azeotropic point is not necessarily an absolute extreme (minimum or maximum point) of the boiling temperature at isobaric condition, but it may be a local extreme (saddle). the tendency of a mixture to form an azeotrope depends on two factors: (a) the difference in the pure component boiling points. (b) the degree of nonideality. the closer the boiling points of the pure components and the less ideal mixture, the greater the likelihood of an azeotrope. the important points about azeotropes are:  they limit the separation achievable by distillation because even with infinite trays, this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. khalid farhod chasib al-jiboury /al-khwarizmi engineering journal ,vol.3, no2 . pp67 –86 (2007) !!óö there is no thermodynamic driving force to separate beyond the azeotrope.  the azeotropic point can be moved, for example by lowering the pressure, so that the desired composition may be obtained.. in fact, for some systems, the azeotrope might not even form if the pressure is changed enough and the azeotrope can be broken.  azeotropes can be used to help separations. adding a third component to a system which forms a minimum boiling point azeotrope with one of the original components can be used to entrain that component, allowing for it to be vaporized away and recovered (marc et al., 1998). theory of azeotropic predictions the ability to predict azeotropic behavior becomes more and more important and complex when the number of components in the mixture increase. this prediction is tested successfully by applying the gibbs-konovalov theorem (malesinski, 1965). they developed correlation equations for expressing boiling temperature of the vapor-liquid equilibria data, isobaric conditions, as a function of liquid composition, where              1 111 ... 2 n n ij n i iijiijiji i ii xxcxxbaxxtxt jjj o (1) where to i is the boiling temperature of pure component i in oc, and n number of component in the mixture. this equation is useful for obtaining isothermals and for exploring the azeotropic behavior of binary and ternary mixtures. the coefficient aij, bij, and cij are binary or ternary parameters which are determined directly from the binary or ternary data. the increase in the number of parameters increases the prediction accuracy. and another correlation for prediction azeotropic behavior of the binary and ternary mixtures, and the kind of azeotrope (minimum, maximum and saddle type), will be discussed below: the gibbs-konovalov theorem (malesinski, 1965) for multicomponent systems states that the following conditions are fulfilled at the azeotropic point where xi = yi at constant pressure: 0 ,             jxpix t i = 1,2,…, n…... (2) the index x`j means that the relationship t is given in terms of all mole fractions as independent variables, except xj. the differentiation is carried out by keeping all the mole fractions constant except xi. for a ternary mixture, the application of (2) namely     0 33 ,2,1   xpxp xtxt to the ternary form of (1) yield that:   021 213323223122112112  ttxxxxxxxxxx oo ….. (3)   05.0221 32212132312 3312111  ttxxxxxxxxxx oo .(4) where xxx 213 1  …………………………………….. (5)     ... 2  xxcxxba jj iijiijijk ……………… (6)            ...432 32 xxexxdxxcb jjj iijiijiijijk  (7) for k = 1 : ij = 12 and � = 1…………….… (8) k = 2 : ij = 13 and � = 2………………. (9) k = 3 : ij = 23 and � = 1………………(10) equations (3) and (4) are nonlinear equations for the unknowns x1 and x2 and if a ternary mixture exhibits azeotropic behavior, the solution for x1 and x2 should lie within 0-1. for binary mixtures, one obtains from   0 2,1  xpxt that:     0221 2111111 2  ttxxx oo ……. (11) this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. khalid farhod chasib al-jiboury /al-khwarizmi engineering journal ,vol.3, no2 . pp67 –86 (2007) !!ôí equation (11) is solved numerically and an azeotrope exists if solution x1 is within the interval 0<x1<1. the use of optimization technique for determining the parameters of the correlation by means of isobaric vapor-liquid equilibria requires minimization of an objective function. the objective function is:         m i cal i obs i ttfo 1 2 . ………………… (12) in a multicomponent mixture under isobaric conditions, there is a possibility for an azeotrope with a minimum boiling point, with a maximum boiling point and a saddle point azeotrope. the thermodynamic conditions determining the kind of the multicomponent azeotrope for isobaric equilibria may be derived as follows: (2) indicates that the boiling temperature of a multicomponent mixture may be expressed as a function of the liquid composition, namely, t(x1, x2, …, xn-1). designating by t and x the coordinates of the azeotropic point and expanding t into a taylor series around the azeotropic point gives:       xxxxxx txxtxxt kkjj kjj k nn              2 2 1,...,,..., 1111 (13) where terms beyond the second derivative were neglected and according to (2) the first derivatives vanish at the azeotropic point. equation (13) is known as the quadratic form and the kind of azeotrope depends on the following determinant: a aaa aaa aaa x t xx t xx t xx t x t xx t xx t xx t x t n nnnn n n nnn n n 1 1,12,11,1 1,22221 1,11211 2 2 2 2 1 2 2 2 2 2 2 12 2 1 2 21 2 1 2 111 1 1 2                          ... ............ ... ... ... ............ ... ... (14) where the derivatives are taken at the azeotropic point. for simplicity, the principal minors of the determinant an-1 are designated as follows: a aaa aaa aaa aaa aa 33 333231 232221 131211 22 2221 1211 ;  (15) on the basis of theorems related to quadratic forms and by considering (13), (14) and (15), the followings can be concluded concerning the possible kinds of azeotropes (table 1): table 1. conditions for determination of kinds of multicomponent azeotropes minimum in t x maximum in t x neither maximum or minimum in t – x, namely saddle type behavior 011 a 022 a 033 a 044 a . . . 011 a 022 a 033 a 044 a . . . neither one of the conditions in the two left hand columns is fulfilled. plotting calibration curves refractive index and density measurements at 30 oc were chosen as rapid and accurate methods for analysis of equilibrium mixtures. calibration curves analyses of all binary systems are usually represented graphically by plotting refractive index against the compositions. combination of refractive index and density measurements were employed for the analysis of the ternary systems graphically, if the concentration of one of the constituents is kept constant while the other two are varied. this was done by interpolation of previously determined refractive index-composition and densitycomposition charts. the schematic diagram of the calibration curve of the ternary system 1-propanol – hexane – benzene is illustrated in figure 1.a, and the calibration curve of the ternary system toluene – cyclohexane – iso-octane is illustrated in figure 1.b, this is a graphical method for analysis of the ternary system. another very accurate method used for analysis is by the use of computer program designed and developed by using this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. khalid farhod chasib al-jiboury /al-khwarizmi engineering journal ,vol.3, no2 . pp67 –86 (2007) !!ôî mathcad software for the purpose of finding the compositions of the ternary or binary systems at a given refractive index and density 1 propanol hexane benzene 0 25 50 75 100 25 50 75 10 0 0 0 25 50 100 75 1. 48 5 1. 48 0 1. 47 5 1. 47 0 1. 46 5 1. 46 0 1. 45 5 1. 45 0 1. 44 5 1. 44 0 1. 43 5 1. 43 0 1. 42 5 1. 42 0 1. 41 5 1. 41 0 1. 40 5 1. 40 0 1. 39 5 1. 39 0 1. 38 5 1. 38 0 1. 37 5 r e fr a c t iv e in d e x 0. 84 6 0. 85 2 0. 85 80. 84 0 0. 83 4 0. 82 8 0. 82 2 0. 81 6 0. 81 0 0. 80 4 0. 79 8 0. 79 2 0. 78 6 0. 78 0 0. 77 4 0. 76 8 0. 76 2 0. 75 6 0. 75 0 0. 74 4 0. 73 8 0. 73 2 0. 72 6 0. 72 0 0. 71 4 0. 70 8 0. 70 2 0. 69 6 0. 69 0 0. 68 4 0. 67 8 0. 67 2 0. 66 6 0. 66 0 d e n s it y fig. 1.a. triangular plot of refractive index – density – composition (calibration curve) of the ternary system 1-propanol – hexane – benzene at 30 oc, in which lines of constant refractive index and constant density are plotted. toluene cyclohexane iso-octane 0 25 50 75 100 25 50 75 10 0 0 0 25 50 100 75 0.8 40 0.834 0.828 0.774 0.768 0.7800.7860.7920.7980.8040.8100.8160.822 0.762 0.756 0.750 0.744 0.738 0.732 0.726 0.720densit y 0.714 0.708 0.702 0.696 0.690 1.415 1.410 1.405 1.400 1.395 1.420 1.425 1.430 1.435 1.440 1.445 1.450 1.455 1.460 refractive index 1.465 1.470 1.475 1.390 fig. 1.b. triangular plot of refractive index – density – composition (calibration curve) of the ternary system toluene– cyclohexane-iso-octane at 30 oc, in which lines of constant refractive index and constant density are plotted. expermintal work apparatus and procedure the experimental determination of vaporliquid equilibrium data are performed using a circulating equilibrium apparatus, fig. 2, in which the gas and liquid phases of a mixture are circulated continuously at constant pressure. the apparatus used was an all-glass recirculating still. this equipment has a side-heating unit which ensures complete mixing of the liquid mixture. the design also prevented liquid drop entrainment and partial condensation in the vapor phase. the equilibrium temperature were measured by a digital thermometer with an accuracy of ±0.1 oc. in each experiment, the liquid mixture was heated in a recirculating still at fixed pressure of 101.3 kpa. equilibrium was reached after 1h where the temperature of the liquid and vapor phases were constant (the boiling point had become stable) and their difference was within 0.1 oc. samples of the equilibrium phases were taken at small volumes and were analyzed by measuring densities and refractive indices at 30 oc. fig.2. flow diagram for equilibrium apparatus. system selection ternary system i the ternary system i consists of 1propanol, hexane and benzene and its binaries. one of the problems in the field of extractive distillation is to find a quantitative method of assessing solvents, in term of the physical properties of the constituents, in order to this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. khalid farhod chasib al-jiboury /al-khwarizmi engineering journal ,vol.3, no2 . pp67 –86 (2007) !!ôï select the most efficient solvent for a particular process for separating closely boiling compounds. the system studied in this work was composed of hexane and benzene. these hydrocarbons are difficult to separate because of closeness of boiling points. 1-propanol was used as a solvent, to determine experimentally the effect of polar components on the separation of binary systems. also, these hydrocarbons having different structures comes from different groups and form non-ideal solution, hexane (straight chain) from alkanes group and benzene from aromatics group and 1-propanol from alcohols group. ternary system ii the ternary system ii consists of toluene, cyclohexane and iso-octane (2,2,4-trimethylpentane) and its binaries. aromatic hydrocarbons have long been known to show non-ideal characteristics when mixed with other type of hydrocarbons. in the commercial production of toluene from petroleum, the toluene must be separated from hydrocarbons having about the same boiling point, thus the separation of toluene as a pure compound by ordinary fractionation is very difficult. also, the importance of using iso-octane (2,2,4-trimethyl-pentane) as the central component in an investigation of orientation effects in the pure liquid components. the system studied in this work was composed of toluene, cyclohexane and isooctane (2,2,4-trimethyl-pentane). these hydrocarbons having different structures come from different groups and form non-ideal solution, cyclohexane and iso-octane from alkanes group and toluene from aromatics group. published data for constituent binary systems 1-propanol – hexane, hexane – benzene, 1-propanol – benzene, and toluene – cyclohexane were reported in the literature (hala et al., 1968; ohe, 1989; hirata et al., 1975). to our knowledge, no isobaric or isothermal vle experimental data have been reported previously in the literature for the binary systems cyclohexane – iso-octane and toluene – iso-octane, and for the two ternary systems 1-propanol – hexane – benzene, and toluene – cyclohexane – iso-octane. possible experimental work errors systematic errors in the experiments can be ruled out since all the analytical methods were carefully controlled (rechecking the analytical procedure) and all the measurements were duplicated. the value of the experimental results depends on the care employed by the experimentalist in eliminating sources of error. obtaining good experimental data requires appreciable experimental skill, experience and, patience. possible causes of the deviation were due to the fact that the mixtures were not ideal mixtures or due to inaccuracy of refractometer, thermometer or barometer or incorrect reading off of their values. the limit of error in reading the refractometer was one in the fifth place, and did not vary noticeably for various mixtures. the estimated precision of the equilibrium mixture composition measurements was ±0.001 mole fraction for the liquid phase and ±0.005 mole fraction for the vapor phase. the estimated uncertainties in the equilibrium temperature and pressure were ±0.1 oc and 0.5 mmhg, respectively. care was taken to assure that equilibrium really existed, that the temperature and pressure were measured at the position where equilibrium existed, and that the taking of samples for analysis did not disturb the equilibrium appreciably. thermodynamic consistency test one of the greatest arguments in favor of obtaining redundant data is the ability to assess the validity of the data by means of a thermodynamic consistency test. the consistency of the experimental data was examined to provide information on the thermodynamic plausibility or inconsistency and to recognize any deviations of the measured values. according to mcdermott-ellis test method, two experimental points a and b are thermodynamically consistent if the following condition is fulfilled (mcdermott and ellis, 1965): d < dmax (16) the local deviation d is given by      n i iaibibia xxd 1 lnln  (17) this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. khalid farhod chasib al-jiboury /al-khwarizmi engineering journal ,vol.3, no2 . pp67 –86 (2007) !!ôð in this method, it is recommended the use of a fixed value of 0.01 for dmax if the accuracy in the measurement of the vapor and the liquid mole fraction is within 0.001. the local maximum deviation, dmax, due to experimental errors, is not constant, and is given by              n i ibibiaia ibiamax y yxyxxxd 1 1111       nn i ibia i iaib p p xxx 11 lnln2               n bi a ibia t ttxx 1 11 ………… (18) table 2. results of thermodynamic consistency test. system d dmax thermodynamic consistency test s ys te m i 1-propanol – hexane 0.0243 0.026 pass hexane – benzene 0.0161 0.021 pass 1-propanol – benzene 0.0274 0.029 pass 1-propanol – hexane – benzene 0.0321 0.035 pass sy st em i i toluene – cyclohexane 0.0196 0.023 pass cyclohexane – isooctane 0.0153 0.018 pass toluene – isooctane 0.0178 0.024 pass toluene – cyclohexane – isooctane 0.0246 0.026 pass the conclusion can be drawn that all the data are thermodynamically consistency statistical measurement and analysis of dispersion to know the applicability and accuracy of any proposed correlation it is very important to know how this correlation fits the experimental data which is done by comparing the obtained results from the proposed correlation with the experimental data. the various measurement of dispersion or variation are available, the most common being the mean overall deviation and average absolute deviation. the mean overall deviation “mean d %” is a more tangible element indicating the overall goodness of the fit of the data by the correlation and it reads: 100% 1      n m mm dmean n i ii obsd i calcdobsd ....... (19) average absolute deviation “aad” n mm aad n i ii calcdobsd    1 ……………… (20) where m is an intensive property and n is the number of data point. these equations are used to calculate mean overall deviation “mean d%” and average absolute deviation “aad” of experimental results of binary and ternary systems. azeotropic predictions the wide concentration field which must be investigated experimentally in order to detect an azeotrope in the ternary mixtures, reflects the importance of the correlation to be able to predict azeotropic behavior. the boiling temperature of the mixture was correlated with the liquid composition by the following equation:              1 111 ... 2 n n ij n i iijiijiji i ii xxcxxbaxxtxt jjj o (1) where to i is the boiling temperature of pure component i in oc, and n number of component in the mixture. this equation is useful for obtaining isothermals and for exploring the azeotropic behavior of binary and ternary mixtures. the coefficient aij, bij, and cij are binary or ternary parameters which are determined directly from the binary or ternary data. the increase in the number of parameters increases the prediction accuracy. for exploring the azeotropic behavior of binary and ternary mixtures equation (1) was solved simultaneously with equations 3 – 10. an this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. khalid farhod chasib al-jiboury /al-khwarizmi engineering journal ,vol.3, no2 . pp67 –86 (2007) !!ôñ azeotrope existed if solution x1 is within the interval 0<x1<1. if the computations did not yield a solution which corresponds to a true azeotrope, the system would not exhibit azeotropic behavior. the following experiment was performed in order to check the validity of the predicted values. ternary solutions with the calculated compositions were prepared and introduced in the recirculating still. the system was boiled until equilibrium was achieved. the analysis yielded the equilibrium compositions of the vapor and liquid. it was seen that the liquid composition deviated very small from the vapor composition, the computed values did not correspond to true azeotropes. on the other hand, the true value of the azeotropic point was identical to the solution or was located in their vicinity. it was observed that the azeotropic boiling temperature was very accurately predicted than the composition. the reason for this behavior is due to the fact that variations in the temperatures in the vicinity of the azeotropic point are usually relatively small in comparison to the concentration (anderson et al., 1978). discussion of results in order to assess the reliability of experimental results, the equilibrium curves were plotted and compared with those from literature (hala et al., 1968; ohe, 1989; hirata et al., 1975), as shown in figures 3 to 8. it may be seen that there is good agreement between the experimental data of this work and the experimental data from literature and confirms the reliability of this work. the fact that the equilibrium curves for both binaries 1propanol – hexane and 1propanol – benzene cross the 45o line indicates that they form azeotropes. 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 mole fraction of hexane in liquid 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 m ol e fr ac tio n of h ex an e in v ap or equilibrium curve experimental data literature data  fig. 3. vapor liquid equilibrium diagram in binary system of 1propanol – hexane. 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 mole fraction of hexane in liquid 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 m ol e fr ac tio n of h ex an e in v ap or equilibrium curve experimental data literature data  fig. 4. vapor liquid equilibrium diagram in binary system of hexane – benzene. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. khalid farhod chasib al-jiboury /al-khwarizmi engineering journal ,vol.3, no2 . pp67 –86 (2007) !!ôò 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 mole fraction of benzene in liquid 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 m ol e fr ac tio n of b en ze ne in v ap or equilibrium curve experimental data literature data  fig. 5. vapor liquid equilibrium diagram in binary system of 1 propanol – benzene. 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 mole fraction of cyclohexane in liquid 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 m ol e fr ac ti on of c yc lo he xa ne in v ap or equilibrium curve experimental data literature data  fig. 6. vapor liquid equilibrium diagram in binary system of toluene – cyclohexane. 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 mole fraction of cyclohexane in liquid 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 m ol e fr ac ti on of c yc lo he xa ne in v ap or equilibrium curve experimental data fig. 7. vapor – liquid equilibrium diagram in binary system of cyclohexane iso octane. 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 mole fraction of iso-octane in liquid 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 m ol e f ra ct io n of is oo ct an e in v ap or equilibrium curve experimental data fig. 8. vapor liquid equilibrium diagram in binary system of toluene iso-octane. the t-x-y diagrams were plotted at isobaric condition, figures 9 to 14. all those experimental results were compared with literature. it may be seen that there is good agreement between the experimental data of this work and the data from literature. the binary mixtures of toluene – cyclohexane and toluene – iso-octane are nearly ideal solution. the other binary mixtures showed positive deviations. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. khalid farhod chasib al-jiboury /al-khwarizmi engineering journal ,vol.3, no2 . pp67 –86 (2007) !!ôó 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 mole fraction of hexane 60 65 70 75 80 85 90 95 100 te m pe r a tu r e , c o t-x-y curves liquid phase experimental data liquid phase literature data vapor phase experimental data vapor phase literature data   fig. 9. boiling point composition curve for 1 propanol – hexane at 760 mmhg. 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 mole fraction of hexane 66 68 70 72 74 76 78 80 82 t e m pe r a t u r e , c o t-x-y curves liquid phase experimental data liquid phase literature data vapor phase experimental data vapor phase literature data   fig. 10. boiling point composition curve for hexane – benzene at 760 mmhg. 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 mole fraction of benzene 74 76 78 80 82 84 86 88 90 92 94 96 98 t e m pe r a t u r e , co t-x-y curves liquid phase experimental data liquid phase literature data vapor phase experimental data vapor phase literature data   fig. 11. boiling point composition curve for 1 propanol – benzene at 760 mmhg. 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 mole fraction of cyclohexane 80 85 90 95 100 105 110 115 t e m pe r a t u r e , c o t-x-y curves liquid phase experimental data liquid phase literature data vapor phase experimental data vapor phase literature data   fig. 12. boiling point composition curve for toluene – cyclohexane at 760 mmhg. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. khalid farhod chasib al-jiboury /al-khwarizmi engineering journal ,vol.3, no2 . pp67 –86 (2007) !!ôô 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 mole fraction of cyclohexane 80 82 84 86 88 90 92 94 96 98 100 t e m pe r a t u r e , c o t-x-y curves liquid phase experimental data vapor phase experimental data   fig. 13. boiling point composition curve for cyclohexane iso-octane at 760 mmhg. 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 mole fraction of iso-octane 98 100 102 104 106 108 110 112 t e m pe r a t u r e , co t-x-y curves liquid phase experimental data vapor phase experimental data   fig. 14. boiling point composition curve for toluene iso-octane at 760 mmhg. the experimental data for binary system were found to be in close agreement with the reported values of the literature. there was no evidence of erroneous data at the entire concentration range because no scattering points were observed and all the points of data fall on smooth curves, showing the experimental values to be consistent. the difference between the experimental points and the smoothing curves are within the analytical accuracy (the estimated precision of the equilibrium mixture composition measurements was ±0.001 mole fraction for the liquid phase and ±0.005 mole fraction for the vapor phase. the estimated uncertainties in the equilibrium temperature was ±0.1 oc). the average scatter of the experimental points from the best line is less than that of the previous investigations in the literature. for system i the experimental data for all the three binaries show that they are non-ideal in nature. when studying the equilibrium of hexanebenzene, the observation made in this investigation was that no separation obtainable at concentration above 97 mole % hexane. the 1propanol-hexane and 1-propanol-benzene systems show minimum boiling azeotropes. for system ii the toluene-cyclohexane system does not form an azeotrope, but it seems that there is a tendency toward azeotrope formation at high cyclohexane concentration (at low-boiling ends of the t-x-y diagram). the cyclohexane – iso-octane system shows nearly ideal behavior. the toluene – iso-octane system does not form an azeotrope, but it seems that there is a tendency toward azeotrope formation at high iso-octane concentration. table 5 indicates the azeotropic composition and temperature of these binaries. the distribution of the experimental vaporliquid equilibrium data for ternary systems in the composition triangle diagram may be readily appreciated. these distributions were presented in figures 15 and 16. each equilibrium composition is shown in figures 15 and 16 by an arrow, with the flight end representing the composition of the liquid phase and the arrowhead that of the vapor phase. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. khalid farhod chasib al-jiboury /al-khwarizmi engineering journal ,vol.3, no2 . pp67 –86 (2007) !!ôõ   1 propanol hexane benzene 0 25 50 75 100 25 50 75 10 0 0 0 25 50 100 75                                                      fig. 15. composition diagram for the ternary mixture 1 propanol + hexane + benzene flight end of arrows (●) indicate equilibrium concentrations of the liquid phase at 760 mmhg and the arrowheads (►) corresponding vapor phase compositions. toluene cyclohexane iso octane 0 25 50 75 100 25 50 75 10 0 0 0 25 50 100 75                                                                                                                         fig. 16. composition diagram for the ternary mixture toluene + cyclohexane + iso octane flight end of arrows (●) indicate equilibrium concentrations of the liquid phase at 760 mmhg and the arrowheads (►) corresponding vapor phase compositions. figure 17 shows equilibrium isotherms on the liquid phase composition diagram obtained from the experimental data by graphical interpolation. hexane ( 68.7 o c ) benzene ( 80.1 o c ) 1 propanol ( 97.2 o c ) 68.868 o c 70.137 o c 71.405 oc 72.674 oc 73.942 oc 75.211 oc 76.479 oc 77.747 o c 79.016 o c 81.553 o c 84.089 o c fig. 17. composition diagram for the liquid phase of the ternary mixture 1 – propanol + hexane + benzene, showing constant boiling temperature contours at 760 mmhg. figure 17 shows a sharp temperature drop occurs from the hexane – benzene binary as small amounts of 1-propanol are added. the drop is less severe at high hexane concentrations. the interior of the surface is nearly flat at points reasonably removed from the pure substances. the flat interior also rises rapidly as pure 1-propanol is reached. a trough with only slight curvature connecting the two binary azeotropes (1-propanol – hexane and 1-propanol – benzene). the surfaces rising from the trough toward pure 1-propanol and also toward the hexane – benzene binary show slightly outward curvature. the ternary system i shown in figure 18 exhibits a ternary azeotrope. the azeotropic composition and temperature of the two binaries are shown in the same figure. in this system, however, there is a point, 0, where boiling temperature is lower than any of the boiling temperatures of the three pure compounds. this composition is known as the ternary azeotrope. the lines of constant boiling temperature surrounding the azeotropic composition 0, and as one proceeds away from 0 the successive this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. khalid farhod chasib al-jiboury /al-khwarizmi engineering journal ,vol.3, no2 . pp67 –86 (2007) !!ôö isotherms that are intersected represent increasing boiling temperatures. hexane ( 68.7 oc ) benzene ( 80.1 oc ) 1-propanol ( 97.2 oc ) o o o 76 o c 65.8 o c 67.2 o c 68 .5 o c 68 .2 o c67 .9 01 o c fig. 18. composition diagram for the liquid phase of the ternary mixture 1 – propanol + hexane + benzene, showing constant boiling temperature contours and the location of the ternary and binary azeotrope at 760 mmhg. in order to determine the coordinates of the ternary azeotrope, figure 19 was drawn. it is a spatial plot of the region where the azeotropic point might be located (a crater-like shape or valley). hexane 1-propanol t em pe ra tu re o c 68.7 oc 97.2 oc 80.1 oc 67.2 o c fig. 19. spatial plot of the ternary system shows the region of the ternary azeotrope. no ternary azeotrope was detected experimentally in the ternary system ii as shown in figures 20 and 21, and the prediction method did not discover any maximum or minimum with the interior of the phase surface, hence, the system does not contain ternary azeotrope. also, the shape of curves indicates that the system does not exhibit azeotropic behavior. isothermals for both ternary systems were obtained as shown in figures 17 and 20. the prominent fact which may be concluded from the behavior of the isothermals in figure 17 is the existence of a ternary minimum boiling point azeotrope in the 1 propanol + hexane + benzene system. on the other hand, it may be concluded from figure 20 that the system toluene + cyclohexane + iso-octane does not exhibit a ternary azeotrope. cyclohexane ( 80.4 oc ) iso-octane ( 99 oc ) toluene ( 110.9 oc ) 82.862 oc 84.124 o c 85.386 o c 86.648 o c 87.910 o c 89.171 o c 90.433 o c 91.695 o c 92.957 oc 94.219 oc 95.481o c 96.743o c 98.005o c 99.267 o c 100.529 o c 103.052 o c 105.576 o c fig. 20. composition diagram for the liquid phase of the ternary mixture toluene + cyclohexane + iso-octane, showing constant boiling temperature contours at 760 mmhg. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. khalid farhod chasib al-jiboury /al-khwarizmi engineering journal ,vol.3, no2 . pp67 –86 (2007) !!õí t em pe ra tu re o c toluene cyclohexane iso-octane 110.9 oc 99 oc 80.4 oc fig. 21. spatial plot of the ternary system toluene + cyclohexane + iso-octane. a comparison of calculated and experimental temperature results using equation 1 is given in figure 22, the other results of binary and ternary systems are illustrated in figures 23 to 29. if there is complete agreement between experimental and predicted temperature values, all the points would fall on the 45-degree line. it seem from figure 22 that the equation 1 is useful for obtaining isothermals and for exploring the azeotropic behavior for binary and ternary system because the deviation of all the points from the 45o line is small. the comparison with experimental temperature values indicates that the calculations show rather good agreement with the data as illustrated in figures 22 to 29. the value of the parameter of equation 1 and comparison between experimental and calculated temperature for binary systems are illustrated in table 3. and, the value of the parameter of equation 1 and comparison between experimental and calculated temperature for ternary systems are illustrated in table 4. 68 70 72 74 76 78 80 82 t ( c ) 68 70 72 74 76 78 80 82 t ( c ) o ca lc . o expt. fig. 22. comparison of calculated and experimental temperature results for hexane – benzene system 65 70 75 80 85 90 95 100 t ( c ) 65 70 75 80 85 90 95 100 t ( c ) o ca lc . o expt. fig. 23. comparison of calculated and experimental temperature results for 1 propanol – hexane system. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. khalid farhod chasib al-jiboury /al-khwarizmi engineering journal ,vol.3, no2 . pp67 –86 (2007) !!õî 75 80 85 90 95 100 t ( c ) 75 80 85 90 95 100 t ( c ) o ca lc . o expt. fig. 24. comparison of calculated and experimental temperature results for 1 propanol – benzene system. 80 84 88 92 96 100 104 108 112 t ( c ) 80 84 88 92 96 100 104 108 112 t ( c ) o ca lc . o expt. fig. 25. comparison of calculated and experimental temperature results for toluene – cyclohexane system 80 82 84 86 88 90 92 94 96 98 100 t ( c ) 80 82 84 86 88 90 92 94 96 98 100 t ( c ) o ca lc . o expt. fig. 26. comparison of calculated and experimental temperature results for cyclohexane – iso-octane system 98 100 102 104 106 108 110 112 t ( c ) 98 100 102 104 106 108 110 112 t ( c ) o ca lc . o expt. fig. 27. comparison of calculated and experimental temperature results for toluene – iso-octane system. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. khalid farhod chasib al-jiboury /al-khwarizmi engineering journal ,vol.3, no2 . pp67 –86 (2007) !!õï 65 70 75 80 85 90 95 t ( c ) 65 70 75 80 85 90 95 t ( c ) o ca lc . o expt. fig. 28. comparison of calculated and experimental temperature results for 1 propanol – hexane – benzene system 80 85 90 95 100 105 110 t ( c ) 80 85 90 95 100 105 110 t ( c ) o ca lc . o expt. fig. 29. comparison of calculated and experimental temperature results for toluene – cyclohexane – iso-octane system as the table 3 indicates that the equation 1 gives values that have an overall average absolute deviations (aad) and overall percentage mean deviations for all six binary systems of 0.271 and 0.323 respectively, for 138 data points. as the table 4 indicates that the equation 1 gives values that have an overall average absolute deviations (aad) and overall percentage mean deviations for all two ternary systems of 0.781 and 0.959 respectively, for 256 data points. comparison between experimental and literature [90] and calculated values using equation 1 and equations 3 to 10 of the azeotropic point for the binary systems are illustrated in table 5, and for the ternary systems were illustrated in table 6. it seems from tables 5 and 6 that the calculated temperature and composition of azeotropic point of binary and ternary systems and detecting the type of azeotropic point by using equation 1 with equations 3 to 10 gives good results comparing with the experimental and literature data. table 3. the value of the parameter of equation (1) and comparison between experimental and calculated temperature for binary systems. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. khalid farhod chasib al-jiboury /al-khwarizmi engineering journal ,vol.3, no2 . pp67 –86 (2007) !!õð table 4. the value of the parameter of equation (1) and comparison between experimental and calculated temperature for ternary systems parameters system i system ii o ve ra ll e rr or 1-propanol + hexane + benzene toluene + cyclohexane + iso-octane a12 -54.125 -18.591 a13 -32.434 -27.409 a23 -11.598 -7.2043 b12 -26.423 -17.344 b13 -18.348 -16.695 b23 6.6892 13.539 c12 -56.826 -15.174 c13 -11.838 -89.674 c23 -22.179 -58.457 d12 -68.378 -20.796 d13 1.0346 3.7671 d23 -31.647 -74.527 e12 63.0217 52.524 e13 -10.659 -25.473 e23 112.729 186.163 no. of data points 121 135 256 mean d % 1.169 0.749 0.959 aad 0.869 0.692 0.781 7 conclusion based on this study, the following conclusions can be made: 1. the recirculating apparatus used with all accessories proved to be very suitable for obtaining vle data. 2. all the data obtained are thermodynamically consistent because they passed the thermodynamic consistency test of mcdermott-ellis test method. 3. a binary azeotrope is an extremal point of the binary mixture temperature functions. while a ternary azeotrope is not necessary a global temperature extreme for the ternary mixture, thus being a saddle point of the temperature surface. 4. ternary mixtures may exhibit distinctly different isotherm maps depending on the existence of azeotropes, their type (minimum-, maximumor saddle boiling), their location, and the relative order of the boiling points of the pure components. 5. equation 1 which is a modified correlation of gibbs-konovalov theorem is very important for obtaining isothermals and for exploring the azeotropic behavior of binary and ternary systems. (a) using equation 1 for the six binary systems of 138 data point give an overall average absolute deviations (aad) and an overall percentage mean deviations of 0.271 and 0.323 respectively. (b) using equation 1 for the two ternary systems of 256 data point give an overall average absolute deviations (aad) and an overall percentage mean deviations of 0.781 and 0.959 respectively. table 5. comparison between experimental and literature and calculated values of the azeotropic point for the binary systems binary system system i system ii 1-propanol(1) + hexane(2) hexane(1) + benzene(2) 1-propanol(1) + benzene(2) toluene(1)+ cyclohexane(2) cyclohexane(1)+ iso-octane(2) toluene(1) + iso-octane(2) experimental temperature oc 65.8 76.0 x1 0.109 0.236 x2 0.891 0.764 literature temperature oc 65.73 76.2 x1 0.114 0.225 x2 0.886 0.775 calculated temperature oc 65.512 75.743 x1 0.146 0.217 x2 0.854 0.783 azeotropic type minimum boiling no azeotropy minimum boiling no azeotropy no azeotropy no azeotropy this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. khalid farhod chasib al-jiboury /al-khwarizmi engineering journal ,vol.3, no2 . pp67 –86 (2007) !!õñ table 6. comparison between experimental and literature and calculated values of the azeotropic point for the ternary systems ternary system system i system ii 1-propanol (1) + hexane (2) + benzene (3) toluene(1)+ cyclohexane(2) + iso-octane(3) experimental temperature oc 67.4 x1 0.342 x2 0.625 x3 0.033 literature temperature oc no data no datax1 x2 x3 calculated temperature oc 67.23 x1 0.346 x2 0.628 x3 0.026 azeotropic type minimum boiling azeotropy no azeotropy this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. khalid farhod chasib al-jiboury /al-khwarizmi engineering journal ,vol.3, no2 . pp67 –86 (2007) !!õò references anderson, t. f., abrams, d. s., grens, e. a., “evaluation of parameters for nonlinear thermodynamic models”, aiche j., 24, 20, 1978. hala, e., pick, j., fried, v., and vilim o., “vapor-liquid equilibrium”, 2nd ed., pergamon press, london, 1968. harold, r. n., “phase equilibrium in process design”, wiley-interscience publisher, new york, 1970. hirata, m., hoen, s., and nagahama, k., “computer aided data book of vapor-liquid equilibria”, kodansha limited, tokyo, 1975. hoffman, e. j., “azeotropic and extractive distillation”, interscience publisher, new york, 1964. malesinski, w., “azeotropy and other theoretical problems of vapor-liquid equilibrium”, interscience, pwn, new york, 1965. marc, j. a., martin, j. p. and thamas, f. t., “thermophysical properties of fluid, an introduction to their prediction”, imperial college press, first reprint, 1998. mcdermott, c., ellis, s. r. m., “a multicomponent consistency test”, chem. eng. sci., 20, 293, 1965. ohe, s., “vapor-liquid equilibria data book”, elsevier scientific publishing company, netherlands, 1989. walas, s. m., “phase equilibria in chemical engineering”, butterworth publishers, london, 1985. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. khalid farhod chasib al-jiboury /al-khwarizmi engineering journal ,vol.3, no2 . pp67 –86 (2007) !!õó عددة وللتنبؤ بحالة سائل لألنظمة المت –عالقات ریاضیة لتمثیل بیانات توازن بخار األیزوتروب خالــد فرھــود. د قسم الھندسة الكیمیاویة الجامعة التكنولوجیة :الخالصة عالقات ریاضیة للتعبیر عن درجة حرارة غلیان الخالئط لألنظمة المتعددة كدالة مباشرة لتركیز السائل تم أقل درجة (متعددة وكذلك الیجاد نوع األیزوتروب اختبارھا بنجاح وطبقت للتنبؤ بحالة األیزوتروب للخالئط ال gibbs(باستخدام العالقات المطورة لنظریة ) حرارة، أعلى درجة حرارة، نوع ثابت درجة الحرارة konovalov ( كذلك نقطة األیزوتروب لألنظمة الثنائیة و الثالثیة تم التحقق منھا بصورة عملیة باستخدام التعیین .سائل لألنظمة الثنائیة والثالثیة –لبیانات العملیة لتوازن بخار البیاني على أساس ا -١"ثالثیة وھيسائل بثبوت الضغط الجوي ألثنین من األنظمة ال –في ھذه الدراسة تم قیاس توازن بخار بنزین و –ھكسان ، ھكسان –بروبانول -١" وكذلك األنظمة الثنائیة التابعة لھ وھي " بنزین –ھكسان -بروبانول ثالثي – ٢،٢،٤(ایزو أوكتان –ھكسان حلقي –تلوین "وكذلك للنظام الثالثي األخر وھو "بنزین –بروبانول -١ –ایزو أوكتان و تلوین –ھكسان حلقي، ھكسان حلقي –تلوین (عة لھ وھي وكذلك األنظمة الثنائیة التاب)" مثیل بنتان .كیلوباسكال ١٠١.٣٢٥تم قیاسھا جمیعًا في ظروف ) ایزو أوكتان النظام الثالثي . القیاسات تمت في برج التوازن الدوار الذي یتم من خاللھ تدویر كال الطورین البخار والسائل وكذلك اثنین من األنظمة الثنائیة " بروبانول-١"الذي یحتوي مركب قطبي وھو " بنزین –ھكسان -بروبانول -١" النظام . تكون حالة األیزوتروب نوع أقل درجة حرارة" بنزین –بروبانول -١ھكسان و –بروبانول -١"وھي .الثالثي األخر وكذلك األنظمة الثنائیة الباقیة ال تكون حالة األیزوتروب تازت بنجاح اختبار الصحة والدقة من الناحیة الثرمودینامیكیة باستخدام طریقة االختبار كل النتائج العملیة اج لـ )mcdermott-ellis.( استخدمت إلیجاد ثوابت ) maximum likelihood principle(طریقة االختیار األفضل المسماة ائیة والثالثیة وھذه الطریقة تضمن من الناحیة سائل لألنظمة الثن –العالقات باستخدام البیانات العملیة لتوازن البخار الریاضیة والحسابیة االختیار األفضل لقیم الثوابت في العالقات حیث إنھا تعمل في حالة كل المتغیرات المقاسة تكون .معرضھ للخطأ وكذلك عندما تكون حالة الألمثالیة في كال الطورین البخار والسائل لألنظمة الثالثیة والثنائیة القیم الصحیحة یجب أن تعین تجریبیًا بواسطة . التقارب بالقیم جید بین البیانات المتنبأ بھا والتي تم قیاسھا عملیًا .استكشاف منطقة التركیز التي یتم حسابھا بواسطة النتائج المحسوبة من ھذه العالقات الریاضیة this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ al-khwarizmi!! engineering!!! journal al-khwarizmi engineering journal, vol. 6, no. 1, pp 24 30 (2010) components and treatments of oilfield produced water ayad a. al-haleem* hamed h.abdulah** essam abdul-jalil saeed*** * , ** department of geology/ college of science/ university of baghdad * email: ayadah62@yahoo.com *** technology institute –baghdad (received 21 june 2009: accepted 29 december 2009) abstract in this study, a review of variety of processes that are used in the treatment produced water prior to reuse or to responsible disposal are presented with their environmental issues and economical benefits. samples of produced water from five locations in rumaila oilfield/in south of iraq were taken and analyzed for their contents of brine, some heavy metals, total suspended solids and oil and grease. moreover, two samples of water were treated using reverse osmosis technique which showed its ability to treat such contaminated water. the results showed that the environmental impact of produced water arises from its chemical composition; i.e., its salt content, its heavy metals, and hydrocarbon contents. keywords: produced water, environment, heavy metals, components 1. introduction produced water is water trapped in underground reservoir rocks and is brought to surface along with crude oil and gas. besides elevated concentration of heavy metals such as barium, uranium, cadmium, chromium, strontium and lead, produced water contains dispersed oil droplets and dissolved organic compounds and significant amount of anion such as carbonate, bromide sulfate. the largest volume of waste in the upstream petroleum industry is produced water. the total volume of produced water in the united states is roughly 21 billion/year [1]. sources of this water may include flow from above or below or within the hydrocarbon zone, or flow from injected fluids and additives resulting from production activities [2]. produced water is usually very salty and may contain suspended and dissolved solids, residual hydrocarbons, numerous organic species, heavy metals, naturally occurring radioactive and chemicals used in hydrocarbon extraction [3,4]. the major components of produced water vary according to the type of production activity associated with these types which includes oil production, gas production and coal bed methan (cbm) production. for example, produced waters from gas production are relatively more toxic than produced waters from oil production due to the higher contents of flow molecular – weight aromatic hydrocarbons such as benzene, toluene, and xylene [5,6]. untreated produced water causes number of problems; these problems are:  excess sodicity which cause clay deflection.  excess soluble salts which can cause plants to dehydrate and die.  reduced oxygen level enough to damage aquatic species [2].  injection formation plugging due to suspended solids, which results in injection pressure increase and decrease in the produced water injection flow rate.  scale problem which causes well bore clogging and fluid flow prevention [7,8,9].  environmental impact due to chemical additive like corrosion inhibitor and h2s scavenger [10]. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ ayad a. al-haleem!!! al-khwarizmi engineering journal, vol.6, no.1, pp 24-30 (2010) 25 a large number of methods were used as treatment technologies [11-21] such as heat treating, gas flotation, chemical separation, filtration, and biological degradation. many methods are available to remove the dissolved hydrocarbons such as adsorption, volatilization, oxidation, ultraviolet, irradiation, precipitation, and biological processes [22,23,24]. several methods are available to remove the suspended solids (like cuttings, sand and clay particles) and there methods are filtration, coagulation, gravity separation, and biological treatment [25,26,27,28]. the dissolved solids which include salt, hardness ions and heavy metals can be treated by processes like ion exchange, precipitation, evaporation, distillation and bio treatment [22,29,30,31]. table (1) summarizes the reviewing of different technologies according to their environmental and cost issues. table 1, different produced water treatment technologies with their cost and environmental issues. treatment method cost environmental effect biological treatment low operating costs nonevery low gravity separation 1. plate separators low operating costs very low 2. hydrocyclones low operating costs very low 3. decanting centrifuge low operating costs very low gas flotation + gravity separation + chemical addition moderate operating costs low membrane filtration (microfiltration, nanofiltration and reverse osmosis low operating costs low carbon adsorption moderate operating costs moderate air stripping low operating costs moderate ultra-violet light low operating costs moderate chemical oxidation (ozone and/or hydrogen peroxide oxidation) moderate operating costs moderate precipitation low operating costs moderate (flocculating polymers, biocides, reverse emulsion breakers, and corrosion inhibitors) high costs moderate high 2. experimental work samples of produced water from five locations at rumaila oilfield (south of iraq) were collected and analyzed chemically for their brine composition and concentration of some heavy metals. also the parameters such as tss oil and grease, and ph are measured. more over, two samples of contaminated water were treated using micro filtration and reverse osmosis membranes. the analysis and treatment were done at almansour state company. experimental apparatus reverse osmosis reverse osmosis (commonly abbreviated as r.o) is a physical process which allows dissolved salts to be removed by forcing water to pass through a semi permeable membrane. the permeate, or product water passes through the membrane, while the dissolved salts, particles and the organic matter which are unable to pass through the membrane are conveyed to the drain as a concentrate or rejected water. the heart f an r.o declinator is the osmotic membrane. the r.o systems use spiral wound aromatic polyamide membranes capable to treat the salinity of seawater as tds. the concentration materials used, particularly for the parts in contact with the water, have proven resistance to corrosion (stainless steel, pvc and poly ethylene). r.o. units are fitted with an automatic system for control of the influent and effluent water pressure and of motor absorption and also equipped with flow meters and conductivity meters. the operation data are 380v, 50hz, three phase flow rate 300 to 6000 l/hr(liter/hour). this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ ayad a. al-haleem!!! al-khwarizmi engineering journal, vol.6, no.1, pp 24-30 (2010) 26 microfiltration filtration is a physical process used to reduce turbidity. the impurities trapped by the filtering cartridge are removed by a backwashing procedure powered by an impeller with calibrated holes installed inside the stainless steel cartridge which is able to spray jets of water across the entire surface of the cartridge and propel the trapped deposits to the drain. the materials used for construction are non toxic and of high quality; these filters allow a degree of filtration of 100 microns to 300 and are able to work at an operation pressure of 10 bar. ph-meter the specifications of an electric meter models 595-ph are:  standard measuring range 0-14 ph.  indicator: digital, liquid crystal (lcd), 3 1/2 digit, h = 1/2".  current output 4-20 ma dc on load < 700 ohm. 3. field observations it is important to mention that according to field investigations in the oilfield under study, procedure water coming from oil wells is four to seven times the volume of oil produced. these volumes represent huge amount of contaminated water that require economical and environmentally friendly methods of treatment to be reused or disposed off safely. also, there are about tens of wells that have been used as disposal wells for produced water after a restricted water treatment. discharging processes were done in aldammam formations which have very low pressure property. although this disposal option was not desirable due to many environmental concepts, the injection continued until the disposal wells were in capable of receiving more water. 4. results and discussion the water analysis of rumaila oilfield is summarized in table (2). although, the waters were taken from five locations, no significant differences are shown in the results since they related to the same oilfield. as known, the properties or constituents of produced water vary according to geological formation, to the type of hydrocarbon being produced and to the enhanced operations which are conducted. it can be seen in higher concentrations of solids, heavy metals like barium, strontium, calcium and bicarbonate ions have the potential to precipitate as scale. table 2, constituents of produced water at five locations of rumaila oilfield. constituent produced water (mg/l) location 1 location 2 location 3 location 4 location 5 sodium 35000 25000 28000 19700 22000 potassium 720 450 410 250 220 magnesium 390 810 670 520 480 barium 280 190 180 220 200 strontium 720 580 630 590 500 sulfate 80 100 190 110 130 chloride 65000 66000 67100 62000 61000 calcium 5500 4400 4100 4000 4700 cadmium 30 25 26 29 21 chromium 110 90 95 90 100 copper 100 85 90 75 95 lead 280 210 220 160 150 nickel 190 170 180 130 140 zinc 150 88 99 110 120 hco3 650 600 610 700 630 ph 8.2 8.5 8.6 8.4 8.1 tss 8000 7500 8100 7600 7900 oil and grease 600 650 670 640 710 the scale can clog flow lines from oily sludge's that must be removed and form emulsion that are difficult to break [9]. however, the high concentrations of some heavy metals can cause many production problems for example the presence of different charge ions such as barium and sulfated calcium and sulfates iron and oxygen can cause deposits at discharge sites. table (3) shows typical concentrations of pollutants in two treated produced water samples. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ ayad a. al-haleem!!! al-khwarizmi engineering journal, vol.6, no.1, pp 24-30 (2010) 27 these data represent good results that have been achieved with this available technology by reverse osmosis membranes. table 3, results using reverse osmosis and micro filtration. constituent untreated (mg/l) untreated (mg/l) treated (mg/l) sodium 35000 28000 100 potassium 720 410 10 magnesium 390 670 nd barium 280 180 10 strontium 720 630 15 sulfate 80 190 nd chloride 65000 67100 150 calcium 5500 4100 70 cadmium 30 26 nd chromium 110 95 nd copper 100 90 nd lead 280 220 15 nickel 190 180 nd zinc 150 99 nd hco3 650 610 10 ph 8.2 8.6 7.4 tss 8000 8100 350 oil and grease 600 670 10 the obtained water quality is suitable for many different usages such as re-injection processes for enhanced oil recovery or irrigation and other human purposes. in the present treatment system, the removal efficiency can be enhanced with an increase in the treatment stages which depend on the required water quality. precipitation was detected at a number of micro filters and membranes which can be attributed to presence of oil, grease and lead contents in water respectively. it was necessary to remove these precipitations by chemical washing for example. 5. conclusions  field observations confirmed that produced water is responsible for many problems like corrosion, scale, microbial growth and dirty equipment.  practices such as discharge to surrounding, storage on the surface in open tanks, re-using with a restricted treatment can arise many oilfield problems.  chemical analysis of the produced water from other drilling locations is required to cover the wide range differences in the chemical and physical properties of water. notation cbm coal bed methan btex benzene-toluene-ethyl benzene-xylene tds total dissolved solids tss total suspended solids h2s hydrogen sulfide pahs polycyclic aromatic hydrocarbons acknowledgment the authors would like to thank engineer mohamed a. al-haleem (from al-mansour state company) for his invaluable help in water treatment and in the interpretation of water characterization. 6. references [1]perry, c.w. and gigliellok, k., "epa perspective on current rcra enforcement trends and their application to oil and gas production wastes, "proceedings of the u.s. environmental protection agency's first international symposium on oil and gas exploration and production waste management practices, new orleans, la, sept.10-13,1990, pp.307-318. [2] john,a.v.,markus,g.p.,deborah e., and robert, j.," a white paper describing produced water from production of crude oil, natural gas, and coal bed methane, "prepared by argonne national laboratory for u.s.department of energy, national energy technology laboratory,jan.,2004. [3]stephenson, m. t., "components of produced water: a compilation of industrial studies", j. pet. tech,. may 1992, pp.548-603. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ ayad a. al-haleem!!! al-khwarizmi engineering journal, vol.6, no.1, pp 24-30 (2010) 28 [4]gray, p. r., "norm contamination in the petroleum industry", j. pet. tech,, jan. 1993, pp. 12-16. [5]georgi w.j.,d.sell, and m.j.baker, "establishing best practicable environmental option practice for produced water management in the gas and oil production facilities,"spe 66545,presented at the spe/ epa/ doe exploration and environmental conference, san antonio,feb.,2001. [6]breit,g.,t.r.klett,c.a.rice,d.a.ferderer,and .kharaka, "national compilation of information about water co-produced with oil and gas," 5th international petroleum environmental conference, albuquerque, nm, oct.20-23,1998. [7]arnold k.e."design concepts for offshore produced-water treating and disposal systems,"j.pet.tech.,feb.1983,pp.276-283. [8]odd,je.,and tomson,m.b.,"why scale forms and how to predict it,"spe production and facilities 9,no.1,feb.,1994,pp.47-54. [9]cline,j.t.,"treatment and discharge of produced water for deep offshore disposal, "presented at the api produced water management technical forum and exhibition,lafayette,la,nov.,1998. [10] knudsen b.,hjelsvold m.,frost t.,svarstad m.,grine p.,willumsen c.,and torvik h.,"meeting the zero discharge challenge for produced water,"spe 86671,paper presented at the spe hse int.conf.29-31 march 2004 in calgary,alberta,canada. [11] freeman,h.m.,editor, standard handbook of hazardous waste treatment and disposal. new york: mcgraw-hill book company, 1989. [12] canadian petroleum association, "production waste management handbook for the alberta petroleum industry", dec. 1990. [13] tchobanoglus, g. and burton, f. l. wastewater engineering: treatment, disposal, and reuse. new york: mcgraw hill, inc., 1991. [14] wojtanowicz, a. k., "oilfield environmental control technology: a synopsis", j. pet. tech., feb. 1993, pp.166172. [15] boysen, d. b., "cost factors associated with managing produced water at cbm properties in the rocky mountain region", 10th annual international petroleum environmental conference, houston, tx, nov. 2003. [16] lawrence, a. w., miller, d. l., and hayds, t. d., "regional assessment of produced water treatment and disposal practices and research needs, "epa exploration and production environmental conference, houston, texas, march 1995, pp.373-392. [17] boysen, d. b., j. e. boysen, and t. larson, "regional, technical, regulatory and economic trends in produced water management", gas research institute publications, nov. 2002. [18] arnold, k. e. and koszela, p. j., "dropletsetting vs. retention time theories for sizing oil/water separator", spe production engineering, feb. 1990, pp.59-64. [19] sullivan, e, j., bowman, r.s.,katz,l., and kinney, k., “ water treatment technology for oil and gas produced water, “ identifying technologies improve regional water stewardship :north-middle rio grand corridor, 21-22 april, 2004. [20] simms, k., kok, s., and zaidi, a., "alternative processes for the removal of oil from oilfield brines", proceedings of the u.s. environmental protection agency's first international symposium on oil and gas exploration and production waste management practices, new orleans, la, sept. 10-13, 1990, pp.17-30. [21] powers, m. l., "new perspectives on oil and gas separator performance", spe production and facilities, may 1993, pp.7783. [22] sublett, k. l., morse, d. e., and raterman, k. t., "a field demonstration of sour produced water remediation by microbial treatment", paper spe 26396 presented at the society of petroleum engineering 58th annual technical conference and exhibition, houston, tx, oct.3-6, 1993. [23] mount,d.r.,gulley,d.d.,and evans,j.m.,"salinity/toxicity relationships to predict the acute toxicity of produced waters to freshwater organisms, "paper spe 26007 presented at the society of petroleum engineers/environmental protection agency's exploration and production environmental conference, an antonio,tx,march 7-10,1993. [24] tao, f. t., curtice s., hobbs, r. d., sides, j. l., wieser, j. d., dyke, c. a., tuohey, d., and pilger, p. f., "conversion of oilfield produced water into an irrigation/ drinking quality", paper spe 26003 presented at the society of petroleum engineering/ environmental protection agency's this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ ayad a. al-haleem!!! al-khwarizmi engineering journal, vol.6, no.1, pp 24-30 (2010) 29 exploration and production environmental conference, san antonio, tx, march 7-10, 1993. [25] chen, a. s. c., flynn, j. t., cook, r. g., and casaday, a. l., "removal of oil, grease, and suspended solids from produced water with ceramic cross flow microfiltration, " spe production engineering, may 1991, pp.131-136. [26] townely, d., bergman, r. j., and goldman, w. a., "reduction of oilfield production wastes using dry cake filters", paper spe 19742 presented at the society of petroleum engineers 64th annual technical conference and exhibition, san antonio, tx, oct. 8-11, 1989. [27] hinds, a. a., donovan, d. m., lowell, j. l., and liao, a., "treatment reclamation and disposal options for drilling muds and cuttings", paper iadc/spe14798 presented at the society of petroleum engineers iadc/spe drilling conference, dallas, tx, feb. 10-12, 1986. [28] abd al-razaq, a.a. haleem, "different techniques to minimize oil wells drilling wastes", ph.d. thesis, college of engineering, university of baghdad, 2007. [29] caswell, p.c., gelb, d., marinello, s. a., emerick, j. c., and cohen, r. r. h., "testing of man-made overland-flow and wetlands systems for the treatment of discharged waters from oil and gas production operations in wyoming", proceedings of petro. safe92, houstin, tx, 1992. [30] canarutto, s., petruzzelli, g., lubrano., and vigna guidi, b., "how compositing affects heavy metal content", biocycle, june 1991, pp.48-50. [31] new logic research, "using vsep to treat produced water : an effective and economical solution", emeryville, usa, 2008, http:/www.vsep.com. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ )2010( 3024، صفحة 1، العدد 6مجلة الخوارزمي الھندسیة المجلد لحلیمایاد عبد ا 30 الماء المنتج من الحقول النفطیة ومعالجات مكونات ***عصام عبد الجلیل سعید** حامد حسن *ایاد عبد الحلیم جامعة بغداد /كلیة العلوم /قسم علوم االرض **،* ayadah62@yahoo.com: البرید االلكتروني * بغداد/معھد التكنولوجیا *** الخالصة ع اع ؤول م تخلص المس تخدام او ال ادة االس بق اع ي تس ا في ھذه الدراسة تم عرض مراجعة لمختلف الطرق المستخدمة في معالجة الماء المنتج والت تباراتھ .البیئیة وفوائدھا االقتصادیة عناصر الثقیلھ و المواد الصلبھ العالقھ والنفط جنوب العراق وحللت لمحتواھا من االمالح وبعض ال/تم اخذ نماذج من خمسة مواقع في حقل الرمیلھ .وثاضافة الى ذلك نموذجین من الماء تم معالجتھا باستخدام تقنیة التنافذ العكسي والتي اظھرت قابلیة ھذه الطریقھ في معالجة ھكذا ماء مل.والدھون الكیمیائي ،أي بمعنى أخر محتواه من االمالح ومن العناصر الثقیلة ومن الھایدرو أظھرت النتائج ان التأ ثیر البیئي من الماء المنتج یكون من تركیبھ .كاربونات this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 4, no. 3, pp 8-17 (2008) correcting working postures in water pump assembly tasks using the ovako work analysis system (owas) hussein s. ketan* atiya kadhim al-zuheri** *production engineering and metallurgy department/ university of technology email: hussketan@yahoo.com **satellite technology center/ directorate of aeronautics and space technology ministry of science and technology email: hilahil92@yahoo.co.uk (received 4 march 2008; accepted 2 september 2008) abstract ovako working postures analyzing system (owas) is a widely used method for studying awkward working postures in workplaces. this study with owas, analyzed working postures for manual material handling of laminations at stacking workstation for water pump assembly line in electrical industrial company (eico) / baghdad. a computer program, winowas, was used for the study. in real life workstation was found that more than 26% of the working postures observed were classified as either ac2 (slightly harmful), ac3 (distinctly harmful). postures that needed to be corrected soon (ac3) and corresponding tasks, were identified. the most stressful tasks observed were grasping, handling, and positioning of the laminations from workers. the construction of real life workstation is modified simultaneously by redesign suggestions in the values of location (positioning) factors for stacking workstation. the simulation workstation executed by mean of parametric cad software. that modifications lead to improvement in the percentage of harmful postures. it was therefore recommended the use of supplementary methods is required to identify ergonomic risk factors for handling work or other hand-intensive activities on industry sites. keywords: owas, working posture analysis, stacking workstation. 1. introduction work-related musculoskeletal disorders (wmsds) have been recognized as a serious social problem because of the rising costs associated with wage compensation, medical expenses, reduced productivity, and lower quality of life [1,2,3]. this is a serious problem in many countries; these injuries now comprise 52% of all work-related injuries in the united states, disable 5 million workers each year, and cost about $100 billion annually [4]. in the netherlands alone, some 250.000 persons each year are declared incapable to work due to physical complaints the percentages of the wmsds of all work-related or occupational injuries increased from 10% in 1998 to 23% in 2000, while the percentages of the occupational injuries of all work-related or occupational injuries and illnesses decreased from 57% in 1998 to 29% in 2000 [5]. these ailments can often be attributed to work-related physical load [6]. it is possible to get reliable information about risk factors of wmsds by using the observational methods such as ovakoworking posture analysis system. 2. posture assessment postural analysis provides an analysis of the operator's posture while working. the emphasis in this section is on minimizing unnecessary operator actions and on reducing the amount of lifting done by operators during work. the psychophysical approach estimates worker capacity to perform a given task based on perception of the difficulty of a task [7]. extreme postures will adversely impact energy expenditure and the strength we can bring to bear mailto:hussketan@yahoo.com mailto:hilahil92@yahoo.co.uk hussein s. ketan al-khwarizmi engineering journal, vol. 4, no. 3, pp 8-17 (2008) 9 to accomplish a task awkward or extreme postures are less efficient than postures that keep joints near the center of their range of-motion [8]. 2.1 ovako working posture analyzing system: owas the physical workload was assessed using the ovako working-posture analysis system (owas). this is a multimode observation method that was originally designed in finland for the steel industry. in the owas observer makes an instantaneous analysis of posture and defines it with a three digit code. the first digit describes the position of the back (four choices), second digit describes the arms (three choices), and the third digit describes the legs (seven choices) [9]. an example of the classification chart is given in figure (1). it is based upon expert judgments of the harmfulness of particular postures. a timebased sampling approach can be used with it so that the categorization can take account of the length of time spent in any can take account of the length of time spent in any particular posture [10]. owas does not have any kind of underlying mathematical model. instead it relies on a lookup table that converts three digit posture codes into action categories (ac). table (1) converts the action category into action requirement. owas action categories were derived based upon work postures and loads managed for each job-task. action categories (ac) classify the relative risk and urgency for intervention to prevent musculoskeletal disorders due to exposure, especially to low back pain (lbp) [11]. the workers’ postures were analyzed according to different work phases (corresponded with the task analysis) calculated in percentages and assigned an action category code [10]. fig.1. example owas classification chart [9]. hussein s. ketan al-khwarizmi engineering journal, vol. 4, no. 3, pp 8-17 (2008) 10 table 1 the owas action code [10]. action category action required ac1 no action required ac2 action required in the near future ac3 action required as soon as possible ac4 action required immediately 2.2 winowas: software for owas analysis the posture evaluation method developed in this study was implemented as a computer software program has a timer, called winowas [12] (figure 2) which can be used to measure the observation phasing. the system was designed to automate all the procedures for the analysis of the postures, except for observing the postures and recording them according to the postural classification. the user observes and records the working postures using automatically paused motion pictures. the motion pictures can be recorded by digital camcorder directly at the working site or transformed from the video in the analog form using a mpeg computer system. when starting the observation, the user enters the location of the movie files along with some information about the work. the observer can also record postures in other ways: by direct observation at the working site, by indirect observation through a video on another monitor, and from pictures or image files. this system enables the user to observe working postures continuously or intermittently. for intermittent observation, the player pauses the movie file automatically for the user to observe the working postures regularly. the user can set the sampling interval. in the continuous observation, the user can record working postures by the event-driven way, controlling the play of the movie file manually. after the postures are recorded, the system analyzes the recorded postures. the frequencies, temporal changes, and durations of postures at each joint are documented, and the predicted workload level of each recorded posture is calculated. a very useful characteristic of the system is that the user can retrieve and view the image of the corresponding posture as a result of the analysis. for example, the image of the posture found to have the highest workload level can be shown by clicking the bar representing the posture on the graph of workload level. the user can easily understand the results of the analysis simply by viewing the postures together. this system may enhance the applicability of working posture analysis by the safety managers in the field. fig. 2. shows the main interface of the winowas. hussein s. ketan al-khwarizmi engineering journal, vol. 4, no. 3, pp 8-17 (2008) 11 3. poor working postures in iraq there are cross-cultural variations in postural habits; iraqis frequently use postures that are unfamiliar to western people, such as deep squatting, kneeling, cross-legged sitting, and so on. the squatting posture was found to require more than 5 times the workload compared to sitting on a chair, based on subjective discomfort. this implies that the squatting posture is not proper for prolonged work, though it is a common posture for many iraqis workers. iraqis workers typically perform their jobs in prolonged squatting postures in shipbuilding shops, automobile assembly lines, farms, and machine repair shops. back injuries in manufacturing and transportation industries were mainly due to overexertion, while they were ascribed to incidental injuries in construction industries. overexertion injuries are related to the repeated exertions and poor working postures during manual materials handling (mmm). non-neutral trunk postures as well as manual lifting of moderate-to-heavy loads have been referred as major risk factors for lbp [5]. figure (3) illustrates the examples of poor working postures, such as prolonged squatting, simultaneous trunk flexion and lateral bending, at workplaces including shipbuilding shops, automobile assembly lines, and farms in iraq. especially in the automobile assembly lines, there exist many jobs that require improper working postures. often, assembly line workers need to raise their arms and bend their trunk, and they have to assume these kinds of postures, say, 500 times a day. fig.3-a. sampling picture of grinding worker’s posture. fig. 3-b. welding task of a mechanics worker. hussein s. ketan al-khwarizmi engineering journal, vol. 4, no. 3, pp 8-17 (2008) 12 4. method 4.1 process description in state company for electrical industries, the winding & insulating department is the one from the departments of the water pump assembly line. the department consists of five workstations included stacking, brazing, insulating, winding and testing. one operator for each workstation performed a job specified to them except the first one (stacking) illustrated in figure (4) where the manual material handling tasks for the laminations stator in that station achievable by two operators working in alternative period due to highly physical stress demand required for that job. according to the requirements of balancing on line, the capacity planning limited to 1000 stator for 8 hours shift work separated by 60 minute standard break period, laminations cylinder are continuous unloaded at the rate of 2.38 lifts per minute (i.e. 2.38 lifts / min. per tier are loaded). the time study for the processes in winding & insulating department confirmed that the long cycle time for first process (stacking) had significant effect in specified the capacity planning and total balancing for the line. this is the bottleneck station in the line. in order to increase the throughout of the line, redesign suggestions for station responsible about maximized cycle time should be execute. the basic configuration for this workstation comprised attention to facilities and tooling systems, material-handling systems, and ergonomic workplace. a checklists survey among 8 workers working at this station in different times, showed that among those who worked in an existing stacking workstation design leads to long cycle time, uncomfortable work posture, bending, squatting, and forceful exertions when unloading stator laminations. depending upon the checklists indications, the existing workstation for stacking process presented in figure (4) needs changes in some components design and reconfiguration for layout of workplace. fig. 4. real life workstation. 4.2 simulation model the main task is the manual handling of the laminations at the stacking workstation in argon welding machine; we focus on ergonomics improvement and minimize the cycle time related to this task. the construction of real life workstation is modified by redesign suggestions in some factors. all the factors are location (positioning) factors of stacking workstation. in particular these factors are (a), (b), and (c) as illustrated in figure (5) show the redesign suggestions of workstation by mean of parametric cad software. the body position category is affected by configuration changes. hussein s. ketan al-khwarizmi engineering journal, vol. 4, no. 3, pp 8-17 (2008) 13 fig. 5. the redesign suggestions of workstation. 4.3 research aims the aims of this study were to: 1. analyze working postures for manual material handling of cupper laminations at stacking workstation for water pump assembly line. 2. develop recommendations for work improvement for the handling job observed. 3. identify the relationship between working postures and strenuous tasks observed such as bending, twisting, and kneeling/squatting. 5. results 5.1 postural analysis existing stacking workstation design data were collected and analyzed using the winowas [12]. the cycle time for completing the task (one lifting) as longer period for the last tier in the pallet. at this tier when the worker grasp the stator laminations is lateral bending with picking up objects below knuckle height, twisting the back without moving the feet. the worker works with bent back, low arms and a standing posture. according to the owas's classification, worker's working postures needed more attention with more than 13% having harmful postures and 13 % needing correction recently. figure (6) summarizes the action categories for the postural observations recorded for the material-handling tasks. the construction ratios of standard working postures were listed in table (2). the worker works with straight back, low arms and a standing posture, but 13% bent and twisted their back and 12% walking. fig. 6. construction of working postures in real life workstation. hussein s. ketan al-khwarizmi engineering journal, vol. 4, no. 3, pp 8-17 (2008) 14 table 2 owas action category frequencies and percentages in real life workstation. ac1 (%) ac2 (%) ac3 (%) ac4 (%) posture frequency % posture frequency % posture frequency % posture frequency % 1321 3 37 2121 1 13 2141 1 13 ------- 1221 2 24 -------- ------- 1371 1 13 -------- ------- total 6 74 total 1 13 total 1 13 total ---- 5.2 posture evaluation in reviewing workstation design the simulation results of posture evaluation in suggestion workstation are listed in table (3). due to the redesign suggestions for workstation, the percentages of observed postures showed that the harmful categories for the handling laminations job caused by ac3 was eliminated and the majority of harmful postures for job was classified as ac2 level increased to 20% rather than real life workstation which may harm the worker in the long run. the range of movement or working posture where risk factors causing load on the structures of the body segment are minimal for comparison with the real life workstation as shown in figure (7). the interobserver reliability was 60% for straight back postures, 60% for arms above shoulder postures, 100% for leg postures, and 100% for weight handled, respectively. table 3 owas code for the postures and percentages in suggestion workstation. ac1 (%) ac2 (%) ac3 (%) ac4 (%) posture frequency % posture frequency % posture frequency % posture frequency % 1321 2 40 2121 1 20 ------------ 1121 1 20 -------------------- 3321 1 20 -------------------- total 4 80 total 1 20 total 0 0 total 0 0 fig. 7. construction of working postures in suggestion workstation. hussein s. ketan al-khwarizmi engineering journal, vol. 4, no. 3, pp 8-17 (2008) 15 6. discussion for real life workstation the observed posture combinations classified according to the harmfulness of the postures, into two action categories ac2, ac3 that will require remedial action in the near future, and as soon as possible, respectively. the most common harmful postures for the job were identified by oaws code 2121 and 2141. the ergonomic risk caused by 2121 was the bending of the back. the risk of 2141 was caused by the bending of the back and kneeling on both knees simultaneously. the 2121 posture was observed when the worker was bending, grasping, and positioning. the 2141 posture was recorded when a worker was positioning the laminations for an argon welding machine. these postures were recorded when the workers were grasping, manual handling, and positioning. the bending and kneeling/squatting of the workers always occurred when they worked near floor level. a change of posture is not easy if working height cannot be brought to a level near the waist or the elbow these postures can be reduced just to 2121 in ac2 code when these strenuous postures considerable in the modification suggestions of workstation. this can be improved by choosing the values 80 cm, 35cm, and 40 cm for factors (a), (b), and (c) respectively according to considerations for a well designed workstation. even with these modifications in workstation the worker’s working postures with 20 % needed correction recently but our suggestions can be improved the most strenuous awkward working postures such as body twisting, bending, kneeling/squatting, and walking of the worker. 7. conclusion this study employed the owas method to study the working postures for four jobs at two construction sites. the aim was to identify the tasks by ergonomic risk factors and develop recommendations for work improvement. the ac2 postures, from the output of winowas, were listed. the most problematic working postures found for the job were bending of the back and squatting/kneeling on both legs. frequent handling of laminations in stressful postures was found for worker. the ac3 postures were identified and work improvements were discussed. the owas method suitable and reliable for analyzing the tasks at assembly workstations. it is a proper method for studying working postures involving the movement of whole body. with the help of videotape and computer technology, owas can be used efficiently in identifying awkward working postures for the shoulders, back and legs. 8. references [1] ayoub, m. m., “problems and solutions in manual materials handling”, the state of the art. ergonomics, 35, 713–728, (1992). [2] ayoub, m.m., & mital, a., “manual materials handling”, london, taylor & francis, (1989). [3] chaffin, d.b., & andersson, g.b.j., “occupational biomechanics (2d ed.)”, new york: john wiley & sons, (1991). [4] chaffin, d.b., “computerized biomechanical models for high exertion manual jobs”, in proceedings of the 3rd pan-pacific conference on occupational ergonomics (pp. 1–15). seoul, korea, (1994). [5] lee, i., kee, d., chung, m.k., & kim, s. h. a., “postural workload evaluation system based on a macro-postural classification”, human factors and ergonomics in manufacturing, vol. 12 (3) 267–277, (2002). [6] de joode, b., verspuy, c., burdorf, and a., “physical workload in ship maintenance: using the observer to solve ergonomics problems. noldus information technology”, erasmus university rotterdam, rotterdam, the netherlands, (2004). [7] lang, a., “the correlation between biomechanical loads and psychophysical ratings”, ms thesis, department of industrial and systems engineering, virginia polytechnic institute and state university, blacksburg, va, (2000). [8] waters, thomas r., et al, “revised niosh equation for the design and evaluation of manual lifting tasks”, ergonomics, v 36 (7), pp. 749-776, (1993). [9] honaker, ronald e., “assessing trailer handling tasks: biomechanical modeling, posture categorization, physiological measures, and subjective measure”, department of industrial and systems engineering, virginia polytechnic institute and state university, blacksburg, virginia, (1996). [10] pinder, andrew, dj., “benchmarking of the manual handling assessment charts (mac) ”, health and safety laboratory, broad lane, sheffield, uk. electronic filename: hussein s. ketan al-khwarizmi engineering journal, vol. 4, no. 3, pp 8-17 (2008) 16 \\ganu\ergonomics\adjp\emm\benchmarking \benchmark report.lwp, (2002). [11] 11gilkey, d., keefe, t., bigelow, p., herron, r., duvall, k., hautaluoma, j., sesek, r., “occupational low back pain in residential carpenters: owas categories and forces of compression and shear”, denver metro area of colorado, colorado, (1998). [12] 12-tampere university technology, occupational and safety engineering, “winowas: a computerized system for the analysis of work postures”, july 12, from the world wide web: http://turva.me.tut.fi/owas/,tampere, finland, (2003). file:\\ganu\ergonomics\adjp\emm\benchmarking\benchmark%20report.lwp file:\\ganu\ergonomics\adjp\emm\benchmarking\benchmark%20report.lwp hussein s. ketan al-khwarizmi engineering journal, vol. 4, no. 3, pp 8-17 (2008) 17 تصحيح أوضاع الؼول في ههام تجويغ هضخت ألواء (( owas))بإستخذام ًظام تحليل الؼول ػطيت ػبذ الكاظن السهيري ** حسيي سالن كيطاى. د* الجاهؼت التكٌىلىجيت / ًتاج والوؼادىإلقسن هٌذست ا* وزارة الؼلىم والتكٌىلىجيا/ دائرة تكٌىلىجيا الطيراى والفضاء** الخالصت ٚفٟ ٘ذٖ اٌذراست، حُ إسخخذاَ ٘ذا إٌظاَ . بىثزة وطز٠مت ٌذراست أٚضاع اٌؼا١ٍِٓ فٟ أِىٕت اٌؼًّ( (owas))٠ُسخخذَ ٔظاَ حح١ًٍ أٌؼًّ / ٌخح١ًٍ ٘ذٖ األٚضاع أثٕاء إٌّالٍت ا١ٌذ٠ٚت ٌٍصفائح فٟ ِحطت اٌٍصك اٌؼائذة ٌخط حد١ّغ ِضخت اٌّاء فٟ اٌشزوت اٌؼاِت ٌٍصٕاػاث اٌىٙزبائ١ت خذ أُٔٗ فٟ ِحطت اٌؼًّ اٌحم١م١ت ٕ٘ان winowas))))ٚبأسخخذاَ بزٔاِح حاسٛبٟ ٠ذػٝ . بغذاد ُٚ ِٓ ٘ذٖ % 26 حُ إػذادٖ ٌٙذٖ اٌغا٠ت، أٚ ِٓ اٌصٕف اٌثاٌث ل١ًٍ اٌضزر((ac2))األٚضاع اٌخٟ حّج ِالحظخٙا ٠ُصٕف بىٛٔٗ أِا ٠مغ فٟ اٌصٕف اٌثأٟ ِٓ األٚضاع ((ac3)) –ٚلذ أِىٓ أٌخؼزف ح١ث ٠حخاج ٘ذا اٌصٕف ِٓ األٚضاع إٌٝ حذخً لز٠ب ٌخصح١حٗ خصٛصا-٠ؤثز بشىً سٍبٟ ػٍٝ أٌّذٜ اٌبؼ١ذ ٕالٍخٙا ٚٚضؼٙا ِٓ لبً اٌؼا١ٍِٓ. ػٍٝ أٌّٙاَ اٌّسببت ٌٕشؤٖ ُِ . إْ أغٍب اٌّٙاَ اٌشالت اٌخٟ حّج ُِالحظخٙا وأج حُىّٓ أثٕاء ِسه أٌصفائح، ُّحاواة ِٓ خالي بزٔاِح اٌزسُ ا٢ٌٟ حُ حط٠ٛز ١٘ى١ٍّت حٍه اٌّحطت اٌّٛخٛدة فؼال ِٓ خالي إلخزاحاث بئػادة ( (cad))ٚباسخخذاَ اٌ ػذد ِٓ اٌؼٛاًِ اٌذاخٍت فٟ حزو١ب ٘ذٖ اٌّحطت بح١ث ٠ّىٓ ص١اغخٙا بشىً آخز ِٚٓ ثُ دراست أٚضاع اٌؼًّ (أبؼاد )اٌخص١ُّ ٌٙا بخغ١١ز ل١ُّ ِّٚا حّج ِالحظخٗ أ٠ضا، أْ . ٚلذ أثّزث حٍه اٌخح٠ٛزاث فٟ ١٘ى١ٍخٙا ػٓ ححُسٓ فٟ ٔسبت أٚضاع اٌؼًّ بخم١ًٍ اٌسٍبٟ ِٕٙا. ف١ٙا إفخزاضا ُّسببت ٌألخطار اٌبشز٠ّت فٟ إلإسخؼّاي اٌطُزق ا ٕالٍت أخزائ١ت ِٓ شأٔٗ أْ ٠ُسُٙ فٟ حٛض١ح اٌؼٛاًِ اٌ ُّ ٚ حٍه اٌخٟ ٠خُ ف١ٙا ػًّ ٠ذٚٞ أػّاي اٌ .ٌّٛالغ اٌصٕاػ١ّتأفٟ <4d6963726f736f667420576f7264202d20d2e5d1c7c120e6cf20dae1ed2020dac8c7d134382d203539> this is an open access article under the cc by license : al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 18, no. 3, september, (2022) p. p. 4859 kinetics of electrochemical removal of nickel using bio-electrochemical reactor with packed bed rotating cylinder cathode zahraa a. kadhim* ali h. abbar** *, ** biochemical engineering department/ al-khwarizmi college of engineering/ university of baghdad, iraq *email: zah.ch97@gmail.com **email: ali.abbar@kecbu.uobaghdad.edu.iq )2022 august 162022; accepted may 25received ( https://doi.org/10.22153/kej.2022.08.003 abstract the kinetics of nickel removal from aqueous solutions using a bio-electrochemical reactor with a packed bed rotating cylinder cathode was investigated. the effects of applied voltage, initial nickel concentration, the rotation speed of the cathode, and ph on the reaction rate constant (k) were studied. the results showed that the cathodic deposition occurred under mass transfer control for all values of the applied voltage used in this research. accordingly, the relationship between concentration and time can be represented by a first-order equation. the rate constant was found to be dependent on the applied voltage, initial nickel concentration, ph, and rotation speed. it was increased as the applied voltage increased and decreased as the initial concentration increased. its relation to the applied voltage can be fitted as follows: � � ������� where ko =0.01695 min-1 and -β=0.431. ph and rotation speed have two dissimilar effects on the rate constant. increasing the ph from 3-6 leads to an increase in the rate constant, while a decrease in the rate constant beyond ph=6 has occurred. increasing the rotation from 100 to 300 rpm results in an increase in the rate constant. however, the rate constant decreases significantly beyond a rotation speed of 300 rpm. keywords: nickel, packed bed rotating electrode, microbial electrolysis cell, kinetics. 1. introduction heavy metals are toxic, non-biodegradable, and could be bio-accumulated in an environment, so they have become the most important environmental issue nowadays [1]. nickel is one of these metals which poses several health and environmental threats, and its removal from wastewater is mandatory [2]. several methods have been utilized for nickel removal, such as physiochemical methods (adsorption, coagulation, chemical precipitation, oxidation), and membrane methods (ion exchange membrane, reverse osmosis)[3]. most of these approaches are not effective, especially when heavy metals exist at low concentrations and suffer from high operational costs [4]. on the other hand, nickel can be removed by reduction on cathode via an electrochemical process, which is nowadays an efficient method in comparison with the traditional methods due to the utilization of electrons as a clean reducing agent [5]. recently, the adoption of cathodic deposition has increased due to the application of three-dimensional electrodes that give a high mass transfer rate and a high specific surface area [6]. in this context, different designs of these fixed bed electrodes have been used, such as reticulated vitreous carbon, felts, metal-plated zahraa a. kadhim al-khwarizmi engineering journal, vol. 18, no. 3, p.p. 4859(2022) 49 foams, and screens [7]. however, nickel removal by cathodic deposition needs high energy to reduce it at the required potential [8]. this drawback has been overcome by using microbial electrolysis cells (mecs), which efficiently remove heavy metals at a considerably lower cost [9]. two distinct regimes could be identified in the cathodic deposition process for any electrochemical process operated in the galvanostatic mode that is preferred for industrial scale. the first regime is electron transport control, while the second regime is mass transport control. in the first case, metal percent removal increases linearly with time, while in the second case, exponential decay of the concentration with time occurs, combined with a decrease in current efficiency with time [10], [11]. therefore, studying the kinetics of cathodic deposition is an essential process by which information about the process dynamics such as reaction rate, order of reaction, and mass transfer properties can be obtained [12]. many studies on the kinetics of nickel electrodeposition from an aqueous solution have been published [13]-[24].most of these studies studied the kinetics based on charge-transfer controlled electrode kinetics [13],[14] or diffusionkinetic control associated with a typical nucleation process[15],[24 ]. a few studies were performed to study the kinetics of nickel removal under mass transfer contro[16],[17]. djaenudin et al. (2017) investigated the kinetics of nickel removal using a double chamber electrodeposition cell (dcec). they found that nickel ion removal in dcec followed a first-order kinetic with a removal rate constant k = 0.12 h-1 (r2= 0.956). doan et al. [17]express the nickel electrodeposition using sherwood and reynolds numbers. first-order kinetics is also documented in detail in the literature for other metals like copper. chu et al.[19] investigated the kinetics of copper removal from aqueous solution using a packed bed cathode. they found that the removal rate of copper is under mass transfer and that the concentration of copper declines exponentially according to the following equation: �� � �exp [− ��� � �1 − exp �− � ���] … (1) where c(t) refers to copper concentration at any time t, second, c0 is initial copper concentration, mg/l, (a) refers to cathodic cross-sectional area, cm2, (u) is the superficial velocity (=volumetric flow rate/a) , cm/s, v is electrolyte volume, cm3, l represents the bed height, cm, (λ) is the characteristic length and its value was stated by the authors to be 7.3 cm[18]. in relevant research achieved by ruotolo and gubulin[23], the kinetic behavior of copper deposition on a fixed-bed electrochemical reactor was studied. they found that the decline of copper concentration is linear for the initial period of electrolysis and then changes to exponential for the rest. however, no rate expression has been reported. khattab et al.[11] investigated the kinetics of copper removal using a packed bed cathode. they discovered that the cu(ii) concentration profile with time can be represented by the rate equation: �� � �exp [−��] … (2) where k refers to rate constant in min-1 to our knowledge, no study has been performed to investigate the kinetics of nickel removal using a bio-electrochemical reactor with a packed bed rotating cylinder cathode, nor has a correlation of rate constant been reported based on this design of the electrochemical system. in the present study, the kinetics of electrochemical removal of nickel from aqueous solution using a bio-electrochemical reactor with a packed bed rotating cylinder cathode were investigated based on the effect of four main parameters: the applied voltage, ni (ii) initial concentration, ph, and rotation speed. 2. materials and methods the bio-electrochemical system adopted in the present research for nickel removal is composed of a rotating fixed bed bioelectrochemical reactor, an electrical motor (type, phoenix-usa), a hotplate magnetic stirrer (ika, germany), a power supply (model uni-t: utp3315tf-l) with two avometers (type, kwun tong, kowloon, hong kong) . figure 1 shows the schematic diagram of the electrochemical system. the bioelectrochemical cell is composed of a cylindrical cell body (15cm in diameter and 11 cm in length) ended above by a flange with dimensions of (15cm in diameter and a thickness of 0.5 cm). the cell and its flange were made from perspex material. cylindrical porous graphite with dimensions (10cm in length and 9.8 cm in diameter with 0.5 cm thickness) and having an apparent surface area of 270.176 cm2 was used as an anode. it was purchased from hp graphite handan co.,ltd. the cathode was a spiral-wound woven wire mesh rotating cylinder. it was made of continuous mesh layers of stainless steel wrapped around a central rode of the same material with dimensions of 15 cm x 0.8 cm. these wrapped mesh layers form a bed with an external diameter zahraa a. kadhim al-khwarizmi engineering journal, vol. 18, no. 3, p.p. 4859(2022) 50 of 2 cm and a length of 4.8 cm and is bounded by two teflon sleeves which have a 2.6 cm external diameter and a 2 cm length. the stainless steel woven screen used in the construction of the cathode has a mesh number of 30 wires per inch and its specific surface area was (38.06cm-1) [19], [20]. the catholyte chamber is made from perspex material. it is composed of two main parts: the first is a supporting cylindrical perforated container having dimensions of (11 cm in length and 7 cm in diameter) perforated with 10 mm holes on its lateral surface. the distance between any two holes was (1.5 cm) and the total number of holes was 40. this supporting container was ended on its top with a flange having the dimensions of (15 cm in diameter with a thickness of 0.5 cm) and contained four holes with a diameter of 0.4 cm for fixing the cathodic chamber with the cell body via bolts and nets. the second part is a cylindrical ion exchange membrane chamber. it was constructed from a cation exchange membrane in a cylindrical form with dimensions of (11cm in length and 5.6 cm in diameter) joined at the bottom with a cylindrical perspex disc with dimensions of (5.5 cm in diameter and 0.5 cm in thickness). the cation exchange membrane was (ionic-64lmr). fig. 1. schematic diagram of the electrochemical system. the anode was inoculated with activated sludge as a source of bacteria taken from a local biological unit of al-karkh wastewater treatment– no.2/baghdad sewage department/iraq and fed with the nutrient medium as a source of carboncontaining (per liter): ch3coona 1 g, nah2po4•h2o 2.45 g, na2hpo4 4.58 g, kcl 0.13 g, nh4cl 0.31 g, adjusted to ph = 7 [21]. the cathode chamber was provided with a catholyte solution composed of nickel chloride (nicl2) at different concentrations based on the condition of the experiment. all chemicals used were analytical grade and purchased from sigma aldrich. a weight to volume ratio of 40g/160ml of catholyte as activated sludge to catholyte was chosen. a fresh cathodic mesh screen was used in every experiment, and it was cleaned by rinsing with a nitric acid solution (1m) in an ultrasound cleaner for 10 min, then washed thoroughly with doubledistilled water before using. experiments were conducted by the agitation of anolyte for one hour at rotation speed (300rpm) using a magnetic bar without connecting the cathode and anode to the power supply for activation of bacteria in the activated sludge, and then the required voltage was supplied to the circuit using the dc power supply by joining the positive lead to the anode while the negative lead of the power source was connected in series with a 10 resistor and the cathode. the electrochemical system was run at a temperature of 25 2 °c. after zahraa a. kadhim al-khwarizmi engineering journal, vol. 18, no. 3, p.p. 4859(2022) 51 applying the required voltage, samples were taken every 10 min for the first hour, every 30 min for the second hour, and then every hour until the end of the electrolysis at 4 h. the concentration of nickel was measured by atomic absorption spectroscopy (varian spectraa 200 spectrometer). 3. results and discussion 3.1 effect of applied voltage to determine the order of reaction kinetics of nickel deposition on the bioelectrochemical cell with a packed bed rotating cylinder cathode, plots of ln(c/co) against the time at different applied voltages were constructed. figure 2 shows the plots of ln(c/co) against time at an applied voltage of 0.5v, 0.7v, 0.9v, 1.1v, and 1.3v with the inset representing the corresponding fitting lines. the effect has been investigated at a constant concentration of nickel at 150 mg/l , ph = 5, and a rotation speed of 300rpm. it was observed from the set of plots that the relation is almost linear with a coefficient of determination (r2) greater than 0.93, confirming that cathodic deposition of nickel obeys first-order reaction kinetics. table 1 displays rate constant (k) values at several applied voltages. it was observed that by increasing the applied voltage, the rate constant increases and the relation between rate constant and applied voltage is almost fitted to an exponential form [11]. this was explained as the nickel transport rate from the solution tower to the cathode surface increases with the increase in the applied voltage, reducing the side effects of hydrogen generation at the cathode. however, by increasing the applied voltage, a mass transfer limitation occurs with a slight increase in rate constant at higher voltage [12]. therefore, the correlation between rate constant and applied voltage could be designated by equation (3): � � ������� … (3) or in linear form as: ln(k)=ln(ko) –βe …(4) where k refers to the rate constant in min-1, ko refers to the rate constant at no current supplied, and e refers to the applied voltage in volts. represents the slope of the line. equation 3 shows that the dependence of the rate constant on the applied voltage is similar to the arrhenius form. the values of ko and can be calculated using the plot of ln(k) versus applied voltage shown in figure 3. from figure 3, =0.431 and the value of ko is equal to 0.01695 min-1 with r2=0.995. a similar correlation was obtained by khattab et al.[11] in their study of the kinetics of copper removal on packed bed cathode. the relation was between rate constant and current density instead of the applied voltage used in the present research. however, both current density and applied voltage represent the driving force for the electrochemical reduction of nickel. fig. 2. plots of ln(c/co) against time at different applied voltages. inset: fitting curves. co=150mg/l, ph=5, 300rpm zahraa a. kadhim al-khwarizmi engineering journal, vol. 18, no. 3, p.p. 4859(2022) 52 table 1, rate constant at different applied voltage. co=150mg/l, ph=5, 300rpm e(volt) k(min-1) r2 0.5 0.02082 0.94838 0.7 0.023233 0.93754 0.9 0.024814 0.95496 1.1 0.027100 0.97199 1.3 0.0296 0.93859 0.4 0.6 0.8 1 1.2 1.4 e(volt) -3.9 -3.8 -3.7 -3.6 -3.5 ln (k ) equation y = 0.431 * x 4.0775 r2= 0.995781 fig. 3. plot of ln(k) against applied voltage. 3.2 effect of the initial concentration of nickel the impact of the initial concentration of ni (ii) on the rate constant was also considered. figure 4 shows the plots of ln(c/co) against time at nickel initial concentrations of 50, 100, 150, 200, and 250 mg/l with the inset representing the corresponding fitting lines. the effect has been investigated at a constant applied voltage of 1.1v, ph=5, and 300rpm. from this set of plots, it can be seen that the relationship is almost linear with a coefficient of determination (r2) greater than 0.94. rate constant (k) values at several nickel initial concentrations are tabulated in table 2. it was observed that the rate constant decreased as the initial concentration increased, as shown in figure 5. a similar trend was observed by khattab et al.[11] in their study of the kinetics of copper removal on a packed bed cathode. at higher concentrations, the system may become under mixed control and, with increasing concentration, the system may become solely under electron transfer control. however, no such phenomenon was observed, as confirmed by the high value of r2. mixed control operations have happened in previous studies [18], [23]. zahraa a. kadhim al-khwarizmi engineering journal, vol. 18, no. 3, p.p. 4859(2022) 53 fig. 4. plots of ln(c/co) against time at different initial concentration. inset: fitting curves. e=1.1v, ph=5,300rpm. table 9, rate constant at different initial concentration. e=1.1v,ph=5,300rpm 40 80 120 160 200 240 c oncentration(ppm ) 0.014 0.016 0.018 0.02 0.022 0.024 0.026 0.028 0.03 k (m in -1 ) fig. 5. effect of concentration on the rate constant (k). conc.(mg/l) k(min-1) r2 50 0.027827 0.969077 100 0.026573 0.981468 150 0.027100 0.971993 200 0.019241 0.941139 250 0.014824 0.972635 zahraa a. kadhim al-khwarizmi engineering journal, vol. 18, no. 3, p.p. 4859(2022) 54 3.3 effect of ph to demonstrate the impact of ph on the rate constant, plots of ln(c/co) against time at different values of ph were constructed as shown in figure 6, with the inset representing the corresponding fitting lines. the effect has been investigated at a constant applied voltage of 1.1v, a nickel concentration of 100mg/l, and 300rpm. from this set of plots, it can be seen that the relationship between ln(c/co) and time is almost linear with a coefficient of determination (r2) greater than 0.95. rate constant (k) values at several initial ph values are tabulated in table 3. it was observed that the rate constant increased with increasing ph up to a value of 6, then started to decrease as ph became more alkaline as shown in figure 7. the interpretation of this behavior depends on the effect of hydrogen evolution as a side reaction occurred on the cathode where its rate increases as ph decreases, leading to a lower transfer of nickel towards the cathode. hence the low value of the rate constant was observed. at ph higher than 6, nickel ions may be precipitated as hydroxides rather than as metal, hence the rate of nickel deposition decreases [22]. therefore, ph = 6 is considered in further investigation of the effect of rotation speed. fig. 6. plots of ln(c/co) against time at different at initial ph. inset: fitting curves. e=1.1v, co=100mg/l,300rpm table 10, rate constant at different initial ph. e=1.1v, co=100mg/l, 300rpm ph k(min-1) r2 7 0.018339 0.974491 6 0.027829 0.969513 5 0.026573 0.981468 4 0.020699 0.972654 3 0.016042 0.989982 zahraa a. kadhim al-khwarizmi engineering journal, vol. 18, no. 3, p.p. 4859(2022) 55 2 4 6 8 ph 0.014 0.016 0.018 0.02 0.022 0.024 0.026 0.028 0.03 k (m in -1 ) fig. 7. effect of ph on the rate constant (k). 3.4 effect of rotation speed the impact of cathode rotation speed on the rate constant was shown in figure 8 as plots of ln(c/co) against time at different rotation speeds, with the inset representing the corresponding fitting lines. the effect has been investigated at a constant applied voltage of 1.1v, an initial nickel concentration of 100mg/l, and ph=6. from this set of plots, it can be seen that the relationship is almost linear with a coefficient of determination (r2) greater than 0.95. rate constant (k) values at several rotation speeds are tabulated in table 2 in figure 9. it can be seen that increasing rotation speed results in an increasing rate constant up to 300rpm, and beyond the rotation speed value of 300 rpm, the rate constant starts to decline. this behavior can be interpreted as increasing the rotation speed results in decreasing the thickness of the boundary layer on the cathode surface; hence more nickel ions could be deposited [7]. fig. 8. plots of ln(c/co) against time at different rotation speed. inset: fitting curves. e=1.1v, co=100mg/l, ph=6 zahraa a. kadhim al-khwarizmi engineering journal, vol. 18, no. 3, p.p. 4859(2022) 56 table 11, rate constant at different rotation speed. e=1.1v, co=100mg/l, ph=6 rotation speed rpm k(min-1) r2 100 0.017811 0.968299 200 0.020271 0.960155 300 0.027829 0.969513 400 0.024358 0.974501 500 0.021013 0.928637 100 200 300 400 500 rotation speed(rpm) 0.016 0.018 0.02 0.022 0.024 0.026 0.028 0.03 k (m in -1 ) fig .9. effect of rotation speed on the rate constant (k) 4. conclusions the cathodic deposition of nickel using a bioelectrochemical reactor with a packed bed rotating cylinder cathode was found to follow first-order kinetics. results show that the rate constant is affected by the applied voltage, initial concentration of nickel, ph, and rotation speed. an exponential correlation between rate constant and applied voltage similar to the arrhenius form was observed. increasing the applied voltage leads to enhancement of the rate constant, while concentration has the opposite effect. ph and rotation speed have two dissimilar effects on the rate constant. increasing ph from 3-6 leads to an increase in the rate constant, while beyond ph 6, the rate constant was found to be declining. the rate constant increases as the rotation speed increases up to 300rpm, then the rate constant declines beyond this value. from a scale-up point of view, the results of the present work are significant in selecting the appropriate values of the applied voltage and rotation speed to get the same hydrodynamic similarity in the industrial application based on their optimum values, namely 1.1 volts and 300rpm. acknowledgment the authors thank the technical staff of the biochemical engineering department, alkhwarizmi college of engineering, university of baghdad for general support. zahraa a. kadhim al-khwarizmi 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(2021). kinetic study of electrochemical deposition of nickel from chloride baths in the presence of saccharin. progress in color, colorants and coatings, 14(3), 149-160. doi: 10.30509/pccc.2021.81710 ) 2022( 48-59، صفحة 3العدد، 18مجلة الخوارزمي الهندسية المجلد زهراء علي كاظم 59 احيائي -دراسة حركية التفاعل في االزاله الكهروكيميائيه للنيكل باستخدام مفاعل كهروكيميائي الثابت الحشوةالقطب الكاثودي الدوار ذو ذات علي حسين عبار** زهراء علي كاظم* الخوارزمي/ جامعة بغداد ة كلية الهندس / ةاالحيائي ة الكيميائي ةقسم الهندس *,** zah.ch97@gmail.com :البريد االلكتروني* ali.abbar@kecbu.uobaghdad.edu.iq**البريد االلكتروني: الخالصة . حيث ثابته حشوه مؤلف من احيائي ذات قطب كاثودي دوار مفاعل كهروكيميائيباستخدام المائيةالنيكل من المحاليل إلزالة حركية التفاعل دراسةتم ). اظهرت النتائج kثابت معدل التفاعل ( الحامضيه علىدوران الكاثود والداله ةللنيكل، سرع البدائي زالمسلط، التركي كل من الجهد الكهربائي تأثير تم دراسة بين تغير التركيز للنيكل العالقة وبناء على ذلك ممكن تمثيل المسلطة الكهربائيةلكل قيم الجهود الكتلة انتقال تأثيران الترسيب الكاثودي للنيكل يحدث تحت الداله الحامضيه وسرعة للنيكل،التركيز البدائي المسلط،وجد ان ثابت معدل التفاعل يعتمد على الجهد الكهربائي االولى. المرتبةمع الزمن بمعادلة تفاعل من تمثيل عالقته مع الجهد الكهربائي المسلط والذي باإلمكانحيث انه يزداد مع زيادة قيمة الجهد الكهربائي المسلط وتقل قيمته مع زيادة تركيز النيكل. الدوران. : التالية بالصيغة بر العامل االساسي المتحكم بعملية الترسيب الكهربائي يعت � � ������� ). 0.431) قيمتها تساوي ( -β) و ( min 0.01695-1) ثابت قيمته تساوي ( okحيث ان ( ) يؤدي الى زيادة ثابت 6) الى (3الداله الحامضيه من ( ان زيادةوسرعة الخلط على ثابت معدل التفاعل غير متشابه حيث كل من الداله الحامضيه تأثيران ) rpm 300) الى ( rpm 100زيادة سرعة التدوير من ( التفاعل.) ينخفض ثابت معدل 6معدل التفاعل بينما عند زيادة الداله الحامضيه الى قيمه اعلى من ( .) rpm 300الى زيادة ثابت معدل التفاعل والذي ينخفض تدريجيا بعد زيادة سرعة الخلط الى قيمه اعلى من ( يؤدي summary al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 5, no. 2, pp 10 -19 (2009) effect of adding alcohols and gas velocity on gas hold up and mass transfer coefficient in bubble columns with draught tube ali abdul-rahman n. jasim chemical engineering department /university of technology (received 10 november 2008; accepted 2 jun 2009) abstract the bubble columns are widely used as a two or three phase reactor in industrial chemical process such as absorption, biochemical reactions, coal liquefaction, etc. to design such a column, two main parameters should be taken in consideration, the gas hold-up ( g ), and the liquid phase mass transfer coefficient kla. the study includes the effect of gas velocity and the addition of alcohols on gas hold-up and mass transfer coefficient in bubble column with draught tube when the length of the column is 1.5m and the ratio of the draught tube diameter to the column diameter equals 0.5 and the air dispersion into the base of the draught tube using a multi hole tuyere is equivalent to a diameter of 0.15 mm and has a free sectional distributor area of 61%. water and three aqueous solutions of 10% concentration methanol, ethanol and isopropanol, were used as the liquid phase. the various gas velocity (0.01-0.1) meter/sec are used and the results were compared in case of using water only without the addition of alcohols. from experimental observations, g and kla increase with increasing gas velocity and with the coalescence inhibition of liquid. keyword: alcohols, gas velocity, gas hold up, mass transfer, bubble column 1. introduction the bubble column is widely used in industry as a simple and relatively inexpensive means of achieving intimate gas-liquid contact. gas is bubbled into a deep pool of liquid in cocurrent or countercurrent flow and is dispersed as a bubble swarm of high interfacial area. the absorption may be accompanied by a chemical reaction. the output from such a reactor is obviously influenced by gas hold-up, by interfacial area and by the internal circulation of liquid induced by the bubbles. in bubble columns the hydrodynamics transport and mixing properties depends strongly on the prevailing flow regime. many investigators have proposed different criteria to differentiate flow regime (shah et al 1982). hyndman (1997) has characterized the upward movement of the bubble swarms into three separate flow regimes. the type of gas distributor physicochemical properties of the liquid can affect the transition between the flow regimes (thorat et al 2004). in past decades, a number of attempts were made to describe the flow pattern in the liquid phase of a bubble column. however, liquid circulation velocity depends upon many flows interrelated parameters, e.g flow regime, gas holdup, bubble size and bubble rise velocity in addition to physical properties of liquid. the liquid phase flow pattern in bubble column was qualitatively described by kawagoe k, (1976) and by schumpe a, and grund, g.r. (1986), who identified the existence of two streams in the column: one heading upwards driven by the buoyancy of gas bubbles and the other carrying the liquid down. normally, the rising stream would be centrally located, but instabilities are likely to occur. ali abdul-rahman n. jasim al-khwarizmi engineering journal, vol. 5, no. 2, pp 10 -19 (2009) 11 gas hold-up is one of the most important parameter characterizing the hydrodynamics of the gas bubble columns. it can be defined as the fraction by volume of the gas phase in two and three phase mixtures in the column. a large number of correlations for gas hold-up have been proposed in the literature (see for example shah et al 1982 and pandit and joshi 1984). the simple relationship between the gas holdup and gas superficial velocity for limited range of operating conditions, is given by: g α n gv the value of n depends on flow regime (shah et al 1982) bubble flow 0.7 < n < 1.2 and churn turbulent 0.4 < n < 0.7. the gas hold-up profile is parabolic with a maximum at the center (pandit and joshi 1984, wu,y. 2001). a number of investigators also reported a decrease in the gas hold-up with an increase in liquid viscosity. godbole et al (1984) proposed a correlation for churn turbulent regime. miyahara et al (1986) have given the gas holdup in draught tube using a sieve plate without liquid flow as follows:   mhdfr fo g g 32/1 103/4.0 1      several studies (mashelkar, 1970, deckwer et al. 1974; urza and jackson, 1975; burckart and deckwer 1976; maclean et al. 1977; schugerl et al. 1977; shiaya and dunn 1978; alvarez cuenca et al. 1980; mangart and pilhofer, 1981; koide et al 1984 and haque et al. 1987) indicate that the knowledge of the residence time distribution of the phases is necessary to determine the volumetric mass transfer coefficient, kla. the assumption of complete mixing is only justified in large diameter columns, say dc ≥ 0.1m. in tall and small diameter bubble columns the determination of kla should be based on the concentration profile measured at cocurrent or counter-current flow along the column and evaluated by means of the axial dispersion model (deckwer et al. 1974, schugerl et al. 1977 and mangartz and pilhofer 1981). however, evaluation of the liquid phase concentration profiles can only be used in the presence of a large concentration difference along the column. this can be achieved by moderate gas velocities (usually vg < 0.1 m/sec) or high liquid flow rates. volumetric mass transfer coefficients depend on the gas velocity, and the sparger design and are sensitive to the physicochemical properties, particularly, those which promote or prevent coalescence. in addition, the column diameter has some influence if it is small say, dc ≤ 0.15 m. furthermore, the kla values may vary spatially. deckwer et al (1974) proposed an empirical correlation of type n gla bvk  this equation can be recommended with n = 0.8, but the constant b depends sensitively on the type of sparger and liquid media. deckwer et al (1981) proposed an empirical correlation for oxygen mass transfer in highly viscous newtonian and non-newtonian liquids in bubble columns; 84.059.000315.0  effgla vk  2. purpose this paper presents a study of the effects of gas velocity and the addition of alcohols to liquid phase on gas hold-up and mass transfer rate for the case that the ratio of draught tube diameter to column diameter is equal to 0.5 and the air is sparged into the base of the draught tube using aqueous solutions differing in coalescence behaviour. 3. experimental section a schematic diagram of the experimental setup used in this work is shown in figures (1, 1.1, and 1.3). aplexiglass column of an inside diameter of 0.15 m and about a total height of 1.50 m with draught tube dimensions inside diameter of 0.075 m and a total height 1.20 m was used. the draught tube was fitted with three support legs at the upper and the lower end of the column so as to locate it in central position at any distance above the base. the column consists of two main sections, namely: the gas inlet section and the liquid recycling testing section. the gas inlet section consists of a gas distributor. ali abdul-rahman n. jasim al-khwarizmi engineering journal, vol. 5, no. 2, pp 10 -19 (2009) 12 at the bottom of this section, two lines are connected together before entering the distributor section each line has a valve to be opened or closed as required. one of these lines is the air inlet flow. air compressor supplied the line with the desired amount of air needed; for the experiment, the amount of air was measured using a gas meter, and two calibrated rotamaters connected in parallel were used to measure the air flow rate. the other line is the nitrogen gas inlet flow. the nitrogen was supplied from a cylinder. a gate valve was used in the nitrogen flow, which must be shut off when air was sparged to the column, and must be opened during desorption process. the liquid testing section contains two openings, one for liquid out-flow and the other for liquid in flow. the circulation of liquid in the column was achieved using a centrifugal pump placed in the recycling line. a ball valve placed in the middle of the recycling line was used to take various samples at various times to measure the concentration of the dissolved oxygen during the operation. fig. 1. experimental-apparatus, 1: air compressor, 2, 4, 5, 7, 17: globe valves, 3: needle valve, 6: gas meter, 8: gas rotameter, 9: two-way valve, 10: gas distributor, 11, 14, 15, 16 ,24: gate valves, 12: draught tube, 13: column, 18, 20: ball valves, 19: centrifugal pump, 21: dissolved oxygen meter (do-m), 22: move table, 23: nitrogen cylinder, pg, pcv: pressure control valve pressure gauge ali abdul-rahman n. jasim al-khwarizmi engineering journal, vol. 5, no. 2, pp 10 -19 (2009) 13 the water is fed to the top of the column and discharged from the bottom of the column using a centrifugal pump. compressed air at (100-150) psig was supplied using a reciprocating compressor. the desired air flow rate was set-up using needle valve and the amount was measured with a gas meter. table 1, physical properties for pure liquids at t=25 ○ c liquid phase ρ kg/m 3 ×10 3 µ pa.s×10 -3 σ n/m νl cm 2 /sec water 0.998 0.997 0.072 0.8986 methanol 0.791 0.83 0.070 0.566 ethanol 0.789 1.003 0.068 0.9085 isopropanol 0.785 0.85 0.066 0.9792 the dissolved oxygen concentration in the liquid phase was measured using oxygen meter, which consists of a gold metal electrode. the liquid phase (batch) consists of the following systems (only water, water-methanol, waterethanol, water-iso propanol). the gas distributor in fig (1.2) was constructed from a ceramic material and the type is a multi hole tuyere. the distributor has equivalent pore diameter of 0.15 mm and a free section of 0.61%. table 2, physical properties for mixtures used with various concentrations at t=25 ○ c liquid phase ρ kg/m 3 ×10 3 µ pa.s×10 -3 σ n/m νl cm 2 /sec watermethanol 10% 0.9815 0.795 0.067 0.8226 waterethanol 10% 0.9817 0.910 0.065 0.9400 waterisoprpanol 10% 0.982 0.972 0.062 0.8932 15 cm t e st in g se c ti o n 7. 5 cm 1 2 0 c m 1 5 0 c m g a s – i n le t se c ti o n fig. 1.2. gas-distributor, 1: ceramic material, 2: pipe, 3: hole. fig. 1.1. column gas inlet 2 1 3 do vg ali abdul-rahman n. jasim al-khwarizmi engineering journal, vol. 5, no. 2, pp 10 -19 (2009) 14 fig. 1.3 column ali abdul-rahman n. jasim al-khwarizmi engineering journal, vol. 5, no. 2, pp 10 -19 (2009) 15 4. results on gas hold-up the average gas hold-up g was calculated in equation (1) using the data of clear-liquid height hl and the height of the aerated liquid hf which were determined by visual observation. f lf g h hh   ... (1) the experimental gas hold-up was found by measuring the difference between initial liquid height and final liquid height. since it was rather difficult to read directly the level of the aerated liquid, the values of gas holdup obtained probably involves an error of about 5%, established via repeated measurements. fig (2) shows the influence of gas velocity for the different liquid phase systems used. the gas hold-up was found to increase with increasing gas through, but interact mutually, depending on the liquid phase properties. the gas hold-up of isopropanol solution is roughly twice as that of pure water for aqueous solutions of aliphatic alcohols; a considerable increase in the gas hold-up with alcohol chain length was observed. the gas hold-up decreased in the following order iso propanol> ethanol > methanol. the decrease in surface tension in the presence of alcohols were not sufficient to explain this phenomenon. bubble dynamics and bubble swarm structure in the presence of surfactant solutions can explain this behaviour qualitatively. in the presence of alcohols, the bubbles become rigid and hence have low rise velocities resulting in a bubbly flow regime up to surprisingly high gas velocities (0.08-0.1 m/sec). 0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.10 0.11 vg (m /sec) 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18 0.20 0.22 0.24 0.26 0.28 ª g (pure water system) (water-ethanol system) (water-methanol system) (water-isopropanol system) fig. 2. gas hold-up vs. gas velocity for various systems ali abdul-rahman n. jasim al-khwarizmi engineering journal, vol. 5, no. 2, pp 10 -19 (2009) 16 0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.10 0.11 vg (m /sec) 0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18 0.20 0.22 0.24 k l a ( s e c -1 ) (pure water system) (water-ethanol system) (water-methanol system) (water-isopropanol system) fig. 3. mass transfer coefficient vs. gas velocity for various systems 5. mass transfer coefficient results the physical absorption of oxygen in the air by liquid was employed to determine the mass transfer coefficient. the mass transfer coefficient kla was calculated using equation (2). the results will be expressed as (kla) exp. the volumetric mass transfer coefficient kla is a function of gas hold-up and mean bubble size. fig (3) shows the influence of gas velocity, for different liquid phase systems used. the kla values for water increases with increasing gas velocity because of the increase of the axial dispersion coefficient dl.   t k cc cc log g la osa isa      1303.2 … (2) a similar dependence of kla on gas velocity was observed for all other liquid phase systems. on account of the strong coalescence inhibition the volumetric mass transfer in (water isopropanol) system reaches twice the values of pure water. for aqueous solutions of aliphatic alcohols, (ethanol methanol), the bubbles become more rigid and hence low rise velocities and bubbles coalescence were obtained so that the mass transfer coefficients were larger in water. 6. conclusions from the present study the following conclusions were made: 1the gas hold-up and mass transfer coefficient increase with increasing gas velocity for vg ≤ 0.1 m/sec. 2gas hold-up and mass transfer coefficient decrease with increasing liquid surface tension. ali abdul-rahman n. jasim al-khwarizmi engineering journal, vol. 5, no. 2, pp 10 -19 (2009) 17 nomenclature ci = concentration of dissolved oxygen at any time (ppm). co = initial concentration of dissolved oxygen (ppm). csa = saturated concentration of dissolved oxygen (ppm). d = column diameter (m). do = hole diameter of gas sparger (m). dl = liquid phase axial dispersion coefficient (m 2 /sec). fr = orifice froud number o g dg v . 2 . g = acceleration due to gravity (m/sec 2 ). hf = level of aerated liquid during operation (m). hl = clear-liquid height (m). kla = over all mass transfer coefficient (sec -1 ). t = time (min). vg or vg = superficial gas velocity (m/sec). greek latters  = hold-up (fractional volume). μ = dynamic viscosity (pa.s) νl = kinematic viscosity ( cm2/sec) σ = surface tension (n/m). subscripts g = gas. l = liquid. 7. references [1] akita, k. and f.yoshida: ind. eng. chem., process des. develop., 16, 76 (1984). [2] alvarez-cunca, m., and m. a. nerenbreg, “oxygen mass transfer in bubble columns working at an liquid flow rates”, aichej., 27, 66 (1980). [3] brennan, r., d., cosserat and j. c. carpentier, “influence of column diameters of high gas through puts on the operation of a bubble column”, the chemical engineering journal, 16, 115 (1978). [4] burekhart, r., and w. d. deckwer, “bubble size distribution and interfacial areas of electrolyte solutions in bubble columns” chem.. eng. sci, 30, 351 (1976). [5] calderbank, p. h., chemical engineer, 45, 225 (1976) (kara et al 1982). [6] deckwer, w. d., burckhart, r. and zoll, g., “mixing and mass transfer in tall bubble columns” chem.. eng. sci. 29, 2177-2188 (1974). [7] franz , k., borner, t., kantorek, h. j. and buchholz, r., “flow structures in bubble columns”, ger. chem. eng., 365-374 (1984). [8] godbole, s. p., schumpe, a., shah, y.t. and carr, n.l., “hyrodynamics and mass transfer in non-newtonian solutions in a bubble column”, aiche j., 30 (20) 213-220 (1984). [9] guy c., carreau, p. j. and paris, j., “mixing characteristics and gas hold-up of bubble column” can.s. chem..eng. 64(2), 23-35 (1986). [10] hyndman, c.l., larachi f, gay c. “understanding gas-phase hydrodynamics in bubble columns”, chem.. eng. sci 52, 6377 (1997). [11] kawagoe, k., inoue, t., nakao. “flowpattern and gas hold-up conditions in gassparged contactors” int. j. chem. eng. 16, (176-183) (1976). [12] koide, k., takazawa, a., komura, m. and matsunage, h. “gas hold-up of volumetric liquid phase mass transfer in solid suspended bubble columns”, j. chem. eng. japan, 17 (5) 459466 (1984). [13] maclean, g.f., l. e. erickson, k. h. hsu, and l. t. fan, “oxygen transfer and axial desperation in an aeration tower containing static mixers”, biotechn. bioengng. 19, 493 (1977). [14] mangertz, k. h., and pilhofer, “interpretation of mass transfer measurements in bubble columns ali abdul-rahman n. jasim al-khwarizmi engineering journal, vol. 5, no. 2, pp 10 -19 (2009) 18 considering desperation of both phases”, chem.. eng. sci., 36, 1069 (1981). [15] mashelkar, r.a., and m.m. sharma, “mass transfer in bubble columns”, trans. inst. chem. eng., 48, t162 (1970). [16] pandit, a.b. and joshi, j.b., “mixing in mechanically agitated gas liquid contactors, bubble columns and modified bubble columns”, chem. eng. sci., 8, 11891215 (1982). [17] pandit, a.b. and joshi, j.b., “three phase sparged reactions, some design aspects”, rev. chem. eng., 2, 1-84 (1984). [18] schumpe, a., grund, g. “the gas disengagement technique for studying gas hold-up structure in bubble column”, can. j. chem. eng. 64, (891-896) (1986). [19] schugerl, k., j. lucke, and u. oels, “bubble column bioreactions”, adv. biochem. eng., ed., t. k. ghose, a. fiechter, and n. blakeborogh, 7, 1 (1977). [20] shah, y. t., kelkar, b. g., godbole, s. p. and deckwer, w. d., “design parameters estimation for bubble column reactors”, aiche, j., 28 (3), 353-379(1982). [21] shiaya, s., and i. j. duna, “dynamic oxygen mass transfer coefficient measurement method for column reactors”, chem.. eng. sci., 33, 1529 (1978). [22] thorat, b. n., joshi, j. b., “regime transition in bubble columns”, sci 28, 423430 (2004). [23] urza, i. j., and jackson, “pressure aeration in a 55-ft bubble column”, ind. eng. chem. process des. dev., 14, 106 (1975). [24] wu, y., ong, b. j., al-dahhan, m. h. “prediction of gas hold-up profiles in bubble column reactors”, chem. eng. sci., 30, 1207-1210 (2001). 19 -10 ، صفحة2، انعذد 5مجهة انخىارزمي انهنذسية انمجهذ عهي عبذ انرحمن نجم (200 9) 19 تأثير اضافة انكحىالت وسرعة انغاز عهى زمن احتجاز انغاز ومعامم انتقال انكتهة في انعمىد انفقاعي رو االنبىب انذاخهي عهي عبذ انرحمن نجم انجايؼح انركُٕنٕجٍح / قسى انُٓذسح انكًٍٍأي انخالصة نقذ شاع أسُخذاو االػًذج انفقاػٍح كًفاػالخ ثُائٍح أ ثالثٍح انطٕس فً أغهة انؼًهٍاخ انكًٍٍائٍح انصُاػٍح يثال ػهى رنك ػًهٍاخ االيرصاص ٔيؼايم أَرقال (g)تُظش االػرثاس ػايهٍٍ يًٍٍٓ ًْا َسثح احرجاص انغاص فً يثم ْزِ االػًذج ٌحة االخز. ٔانرفاػالخ انثإٌكًٍٍائٍح ٔاسانح انفحى ٔغٍشْا .(kla)انكرهح تاسرخذاو ػًٕد فقاػً (kla)ٔيؼايم اَرقال انكرهح (g)ٌرضًٍ انثحث دساسح ذأثٍش أضافح انكحٕالخ ٔذغٍش سشػح انغاص ػهى َسثح احرجاص انغاص (bubble column) يٍ َٕع (draught tube) 0.5 يرش َٔسثح قطش 1.5 تطٕل ( ًانؼًٕد انذاخه(draught)ًانى قطش انؼًٕد انخاسج ) . ذى اسرؼًال ثالثح يحانٍم %61 يهى ٔتًساحح جشٌاٌ يراحح 0.15 تقطش يكافئ يقذاسِ (multi hole tuyere)اسرؼًم يٕصع انغاص يٍ َٕع ثاٍَح ٔذًد يقاسَح انُرائج فً حانح / يرش(0.1-0.01)حٍث اسرخذيد سشع يرؼذدج نهغاص ( االٌضٔتشٔتإَل– االٌثإَل –انًٍثإَل )% 01نهكحٕالخ ترشكٍض انرجاسب انؼًهٍح اَّ تضٌادج سشػح انٕٓاء ٔانقذسج ػهى يُغ ذجًغ انفقاػاخ ٌؤدي انى صٌادج َسثح احرجاص اظٓشخ .اسرخذاو انًاء فقط دٌٔ أضافح انكحٕالخ (.kla)ٔيؼايم اَرقال انكرهح (g)انغاص microsoft word ? ????? ???? ????13-21 this is an open access article under the cc by license : al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 17, no. 3, sptember, (2021) p. p. 13-21 phytotoxicity of salvinia molesta in diesel exposure israa abdulwahab al-baldawi* siti rozaimah sheikh abdullah** nur’ izzati ismail *** asia fadhile almanso**** salwa shamran jasim***** *,*****department of biochemical engineering/ al-khwarizmi college of engineering/ university of baghdad/ baghdad/ iraq **,***department of chemical and process engineering/ faculty of engineering and built environment/ universiti kebangsaan malaysia/ selangor/ malaysia ****department of ecology/ college of science/ university of basrah/ basrah/ iraq *email: israa@kecbu.uobaghdad.edu.iq **email: rozaimah@ukm.edu.my ***email: nurezatyismail@ukm.edu ****email: asian.almansoory@yahoo.com *****email: salwa.shamran@gmail.com (received 8 august 2021; revised 6 september 2021; accepted 9 september 2021) https://doi.org/10.22153/kej.2021.09.001 abstract phytoremediation is one of the methods to remove various types of pollutants from water and soil using plants. salvinia molesta, an aquatic plant, is chosen in this study to determine its ability to degrade diesel as the pollutant in synthetic wastewater with different diesel concentrations (0, 8,700, 17,400, and 26,100 mg/l) for 14 days. total petroleum hydrocarbon (tph) has been used as an indicator to represent diesel concentration variation in wastewater. degradation of tph was 85.1% for diesel concentration of 8,700 mg/l, compared with only 53.9% in the corresponding control without plant. while, acute toxicity on s. molesta exposed in diesel concentrations of 17,400 and 26,100 mg/l was observed and eventually had caused the plants to die after 14 days of exposure. additionally, throughout the phytotoxicity test, the biomass of s. molesta was found to fluctuate confirming inhibition on plant to survive with diesel contaminated water compared with the corresponding control without contaminant. based on the results obtained it is suggested to decrease diesel concentration less than 8,700 mg/l in future study due to insolubility of diesel in water and the toxicity to the aquatic plants keywords: degradation, salvinia molesta, phytoremediation, total petroleum hydrocarbon (tph). 1. introduction diesel is the main fuel used in the world due to urbanization and industrial development causing insoluble oil-in-water emulsions among their basic contaminants. this problem is of considerable matter because it can cause trouble during conventional wastewater treatment [1]. phytoremediation is a growing treatment approach that is fast gaining attention and offering efficient and economical clean-up of toxic wastewater contaminated with heavy metals [2], hydrocarbons [3], agricultural wastes [4], dyes [5,6], and chlorinated solvents [7]. phytotoxicity has been used to test plants' ability to tolerate high concentration of diesel [8]. the approach is also applied to remove pollutants from wastewater with different capability. the use of plants in phytoremediation is cost-effective and ecologically sounds to remove, degrade, assimilate, and metabolize contaminants. direct degradation, transpiration of volatile organic israa abdulwahab al-baldaw al-khwarizmi engineering journal, vol. 17, no. 3, p.p. 1321 (2021) 14 compounds via the leaves, biochemical transformations within rhizosphere by microbial, and mineralization process at the rhizosphere zone by associated mycorrhizal fungi and microbial consortia [9] are among the mechanisms in phytoremediation for organic contaminants are. according to vieira et al. [10], microorganisms can degrade hydrocarbons with two conditions aerobic and anaerobic in contaminated soil or underground water [10]. though, researcher prefers to use aerobic condition because of high efficiency removal in shorter time. however, the use of continuous aeration is considerably more expensive due to high biomass residues that need further treatment and increase energy consumption for aeration system. in wastewater treatment, aquatic plants were applied to eliminate nutrients, heavy metals, suspended solids, toxic organics from agricultural landfill, urban storm water runoff and acid mine drainage [11]. in this study, an aquatic plant of salvinia molesta was used. it can be easily found in hot and cold regions, and it is a malaysian native plant. besides having a rapid growth rate, this aquatic fern species also has the capability to accumulate pollutants. it is a free-floating fern; stems rootless, hairy, have horizontal stems that can be float with water surface, and grow at each node, a pair of floating or emergent leaves [12] with its growth is rapid and irregularly [13]. it can spread rapidly and prolifically into a monoculture which can shade out underwater natives, leaving large bare bottom areas [14]. dhir et al. [15] demonstrated that natant salvinia was able to accumulate high concentrations of chromium (cr) from wastewater. the purpose of conducting this research is to identify the ability of s. molesta to survive in different concentrations of dieselcontaminated water and determine its efficiency to degrade diesel. 2. materials and method 2.1 phytotoxicity test design the investigation was performed under a greenhouse conditions in universiti kebangsaan malaysia. in this study, 13 aquariums made of glasses were used for this phytotoxicity test to avoid oils sticking to the walls. the length, width and depth for aquarium were 30 cm each. it was filled with 15 l of synthetic wastewater containing diesel. three replicates of aquarium (r1, r2, and r3) for each concentration were prepared and another three aquariums without plant as control contaminant (cc) as shown in fig. 1. only one aquarium is act as plant control (pc) (without diesel contaminant). nine healthy aquatic plants of s. molesta (fig. 2) at three weeks old were placed in each aquarium filled up with 15 l of water mixed with diesel available from a regional petrol station as synthetic wastewater with different concentrations (0, 8,700, 17,400, and 26,100 mg/l). the investigation was run in an open natural lab. fig. 1. design of phytotoxicity test at different diesel concentrations. fig. 2. the aquatic plant of salvinia molesta [*13]. r1  r2 r3 cc r1  r2 r3 cc r1  r2 r3 cc pc 8,700 mg/l 17,400 mg/l 26,100 mg/l 0 mg/l israa abdulwahab al-baldaw al-khwarizmi engineering journal, vol. 17, no. 3, p.p. 1321 (2021) 15 2.2 properties of water quality the phytotoxicity test was conducted throughout 14 days of lab work with samplings taken on day 0, 3, 7 and 14. the physicochemical variables of ph, temperature, t (˚c), dissolved oxygen, do (mg/l), and oxidation reduction potential, orp (mv) in solution were monitored by a iq150 multi-probe (i.q scientific instruments, u.k.) for temperature, orp and ph measurement, and gli international dissolved oxygen sensor (model 63, u.s.a) for do. 2.3 tph detection in water water samples of 100 ml each from growth medium were taken regularly in clean bottle from each aquarium on tasting time for all phytotreatment to analyse diesel as total petroleum hydrocarbon (tph). liquid–liquid extraction method, and gas chromatography were used to determine tph concentration in the water [16] according to procedure by the environmental protection agency, epa method 8041 [17]. dichloromethane (merch, germany) was utilized as a solvent. in 1 l separatory funnel, 100 ml (wastewater sample) and 25 ml dichloromethane (as solvent) were shaken for 2 min. the upper layer of water was removed and the bottom layer was taken whereby the water from the bottom layer was further removed using sodium sulphate. the residual water was evaporated for three to four days under an overhead fume hood. the remaining was then full up to 2 ml of gc vial. tph concentration in samples were analyzed by gc–fid (agilent technologies, model 7890a, gc system, u.k.). capillary column gas chromatography was used for this purpose. the tph degradation on each sampling day was calculated by equation (1) [8]:   tph -tphsd0tph degradation 100 tph0 %   …(1) with, tph0 is the total petroleum hydrocarbon on sampling day 0 and tphsd is the total petroleum hydrocarbon on each sampling day. 2.4 plant sampling and growth measurement the progress of s. molesta with various diesel concentrations (0, 8,700, 17,400, and 26,100 mg/l) was monitored during 14 days. on each sampling day (0, 3, 7, and 14), one plant was collected from each aquarium. s. molesta was washed wholly with water and then dried using cloth to determine its wet weight. finally, the dry weight of plant was obtained by drying it at 70°c for 72 h in an oven (memmert, germany) [18]. 2.5 statistical analysis all results of removal efficiency and plant biomass were directed to the analysis of variance (anova), using the glm procedure in software spss version 16 (ibm, usa). differences between means were tested using the duncan method. all statistical analysis tests were performed using a significance level of 5% [19]. 3. results and discussion 3.1 observing physical parameters as depicted in fig. 3, physical parameters during the phytotoxicity test were determined for 0, 8,700, 17,400, and 26,100 mg/l diesel concentrations to determine the conditions of experimental work. in general, the results throughout the 14-day exposure show that the temperature and ph along the exposure period varied between 26.2-29.2°c and 5.3-7.2, respectively. in temperate climate, temperature (20–30°c) is suitable for biodegradation of mineral oil hydrocarbons [20]. ph in aquarium with diesel is acidic differ from plant control (0 mg/l) which in range of neutral among the treatments due to microbial utilisation of straightchain hydrocarbons [8]. according to ong et al. (2010), do and orp measurement throughout phytotoxicity test it is indicator of aerobic or anaerobic condition of treatment [21]. the do range decreases from 6.22 to 1.58 mg/l, and orp increased throughout 14 days from -105.4 to 105.5 mv. there were decreases in dissolved oxygen as shown in fig. 3 but the environment of treatment was within aerobic and anoxic conditions. faulwetter et al. [22] stated that aerobic processes were created at high orp while lower orp promote anaerobic processes. in addition orp values were indicated the media of treatment in the aerobic and anoxic range. israa abdulwahab al-baldaw al-khwarizmi engineering journal, vol. 17, no. 3, p.p. 1321 (2021) 16 fig. 3. physical parameters throughout 14-day phytotoxicity test to diesel exposure 3.2 plant growth throughout phytotoxicity study throughout the 14-day test, plant growth parameters were recorded as shown in fig. 4. generally, aquatic plant of s. molesta was inhibited when exposed to diesel contaminant compared to the corresponding control without contaminant. for diesel concentrations of 8,700 mg/l after 3 days of exposure, the plants were gradually withered and inhibited in their growth until day 14. the biomass of aquatic plant of s. molesta decreased until it died at the end of 14 days. the plants were inhibited directly after exposure where all plants died after 3 days in the higher diesel concentrations (17,400 and 26,100 mg/l). the inefficiency and death of the aquatic plant s. molesta was due to the high toxicity and water-diesel insolubility. therefore, the floating layer of diesel was attached to s. molesta floating leaves and emergent roots and caused the death of plants. israa abdulwahab al-baldaw al-khwarizmi engineering journal, vol. 17, no. 3, p.p. 1321 (2021) 17 fig. 4. growth parameters of salvinia molesta with different diesel contamination 3.3 tph removal the gc results of tph concentrations under different treatments of diesel contaminant (8,700, 17,400 and 26,100 mg/l) with plants and without plants (cc) throughout the 14-day treatment time are demonstrated in fig. 5. for all concentrations, there were obvious decreases of tph concentration, due to several reasons: 1) phytoremediation; 2) bioremediation; 3) absorption of diesel by plant leaves and roots; and 4) evaporation of hydrocarbons [20; 23; 24]. the percentage of tph removal for different treatments of diesel contaminated water (8,700, 17,400 and 26,100 mg/l) with vegetated and the non-vegetated ones (cc) within 14-day treatment time are represented in fig. 6. fig. 5. tph concentration throughout 14 day of diesel exposure. israa abdulwahab al-baldaw al-khwarizmi engineering journal, vol. 17, no. 3, p.p. 1321 (2021) 18 the tph degradation in different treatments was up to 85.1-48.1% while the degradation in the controls was only 49.7–57.8%. in this study, for concentration of 8,700 mg/l, at the end of 14 days the removal efficiency was 85.1% even though the s. molesta was inhibited after three days of exposure as illustrated in fig. 4. cohen et al. (2002), tested and found that s. molesta died with 1% (≈8,700 mg/l) diesel concentration similar results to our findings for 8,700 mg/l [25]. the results from the statistical analysis showed significant different between treatments with and without plants and also within days for 8,700 mg/l diesel concentration as visible in fig. 6. s. molesta was inhibited directly after exposure in 17,400 and 26,100 mg/l and at the end of 14 days, all plants died. cohen et al. [25], observed that when azolla pinnata, pistia stratiotes and s. molesta were floated in pots in site experiment containing soil contaminated at the surface with diesel fuel (2.4 lm-2) and flooded with water, the plants were affected fast and led to plant die, thereafter bacterial flocks grow around the dead aquatic plants which enhanced the diesel degradation. according to peng et al. (2009), the tph can be degraded either by physical, chemical or biological action, while in control contaminant without plants; the degradation is usually due to volatilization, eluviation or photolysis [26]. so for this case, the action mentioned by peng et al. (2009), worked together and we got the percentage of degradation of 54.9 and 48.1%, and 52.4 and 47.7% for treatment with diesel concentrations of 17,400 and 26,100 mg/l and its related control contaminant with the absence of plant respectively fig. 6. statistically analysis between treatments with and without plants for 17,400 and 26,100 mg/l diesel concentrations showed no significant difference between them due to the inhibition of the plant after direct exposure [27]. vieira et al. [28] verified that the microorganisms were capable to remove tph at 78 to 83% (initial concentration was 11,000 mg/l) from diesel oil and gasoline fuel polluted effluent after 15 days of treatment. fig. 6. tph degradation by salvinia molesta with: (a) 8,700 mg/l diesel (b) 17,400 mg/l diesel, and (c) 26,100 mg/l diesel. a, a: means significant different between treatments (with and without plants) at p < 0.05; aa: not significant different between treatments (with and without plants) p > 0.05 4. conclusions the results from phytotoxicity test with aquatic plant of salvinia molesta has demonstrated the inhibition of s. molesta when exposed to water contaminated with diesel at concentrations of 8,700, 17,400, and 26,100 mg/l. the high removal efficacy was 85.1% for diesel concentration of 8,700 mg/l, due to physical, chemical, biological, volatilization, eluviations, and photolysis processes. based on the results obtained it is suggested to decrease diesel concentration less than 8,700 mg/l in future study due to insolubility of diesel in water and the toxicity to the aquatic plants. israa abdulwahab al-baldaw al-khwarizmi engineering journal, vol. 17, no. 3, p.p. 1321 (2021) 19 acknowledgements the authors would like to express their deepest gratitude to universiti kebangsaan malaysia (frgs/1/2019/tk02/ukm/01/1) and tasik chini research centre for supporting this research project. they also acknowledge the iraqi ministry of higher education and scientific research for providing a doctoral scholarship for the first author. 5. references [1] m. f., imron, s. b., kurniawan, h. s., titah, “potential of bacteria isolated from dieselcontaminated seawater in diesel biodegradation”, environ. technol. innov, vol.14, pp. 100368, 2019. 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[28] p.a., vieira, r.b., vieira, f.p., de franca, v.l, cardoso, “biodegradation of effluent contaminated with diesel fuel and gasoline”, j. hazard. mater., vol. 140, pp. 52-59, 2007. )2021( 1321 صفحة ، 3العدد ،17المجلد الهندسية الخوارزمي جلةم اسراء عبد الوهاب البلداوي 21 السمية النباتية لسالفينيا موليستا في التعرض للديزل **سيتي رزيمة الشيخ عبد هللا *البلداويإسراء عبدالوهاب *** نور عزت اسماعيل *****سلوى شمران جاسم **** آسيا فاضل المنصوري االحيائية كلية الهندسة الخوارزمي/ جامعة بغداد/ بغداد/ العراق ئية هندسة الكيمياال قسم *****،* سيالنجور/ ماليزيا /جامعة كيبانغسان ماليزيا /كلية الهندسة المدنية والبيئة /الهندسة الكيميائية والعملياتقسم **،*** العراق /البصرة /جامعة البصرة /كلية العلوم /قسم البيئة **** israa@kecbu.uobaghdad.edu.iq *البريد االلكتروني: rozaimah@ukm.edu.myالبريد االلكتروني:** nurezatyismail@ukm.edu*البريد االلكتروني:** asian.almansoory@yahoo.com*البريد االلكتروني:*** salwa.shamran@gmail.comالبريد االلكتروني:**** * الخالصة مولستا ، وهو نبات مائي ، في تعد المعالجة النباتية إحدى طرق إزالة أنواع مختلفة من الملوثات من المياه والتربة باستخدام النباتات. تم اختيار سالفينيا ٢٦١٠٠، ١٧٤٠٠، ٨٧٠٠، ٠هذه الدراسة لتحديد قدرته على تحلل الديزل باعتباره الملوث في مياه الصرف الصناعي بتركيزات مختلفة من الديزل ( كيز الديزل في مياه الصرف الصحي. كان تدهوركمؤشر لتمثيل اختالف تر (tph) يوًما. تم استخدام إجمالي الهيدروكربونات البترولية ١٤مجم / لتر) لمدة tph 85.1 ٪ البالغ الديزل مع ٨٧٠٠لتركيز مقارنة ، لتر / البالغة ٥٣٫٩ملجم الديزل تركيزات تسببت بينما نبات. بدون المقابل الشاهد في فقط ٪ يوًما من التعرض. باإلضافة إلى ذلك ١٤النهاية في موت النباتات بعد وتسببت في s. molesta ملغم / لتر في حدوث سمية حادة في ٢٦٫١٠٠و ١٧٫٤٠٠ لـ الحيوية الكتلة أن النباتية ، وجد السمية بالديزل مقارنةً s. molesta ، خالل اختبار الملوثة المياه الحياة مع قيد للبقاء على النبات تثبيط لتأكيد تتأرجح ء. فقط نبات مع الما ملوث التي بدونحواض باال <4d6963726f736f667420576f7264202d2031342d20323320dae1ed20dfc7e3e120e6cf20dae1ed20e6c7e1c7c120e6d1c7e3ed> al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 16, no. 2, june, (2020) p. p. 1423 analysis of different hand and finger grip patterns using surface electromyography and hand dynamometry a. buniya* ali h. al-timemy** a. aldoori*** rami n. khushaba**** *,**,***biomedical engineering department/ al-khwairzmi college of engineering/ university of baghdad/ iraq **centre for robotics and neural systems (crns)/ cognitive institute/ plymouth university/ uk, ****australian center for field robotics (acfr)/ university of sydney/ sydney /australia *email: alikamil85@kecbu.uobaghdad.edu.iq **email: ali.altimemy@kecbu.uobaghdad.edu.iq ***email: alaaaldoori@kecbu.uobaghdad.edu.iq ****email: rami.khushaba@sydney.edu.au )received 19 november 2019; accepted 5 may 2020( https://doi.org/10.22153/kej.2020.05.001 abstract recording an electromyogram (emg) signal is essential for diagnostic procedures like muscle health assessment and motor neurons control. the emg signals have been used as a source of control for powered prosthetics to support people to accomplish their activities of daily living (adls). this work deals with studying different types of hand grips and finding their relationship with emg activity. five subjects carried out four functional movements (fine pinch, tripod grip and grip with the middle and thumb finger, as well as the power grip). hand dynamometer has been used to record the emg activity from three muscles namely; flexor carpi radialis (fcr), flexor digitorum superficialis (fds), and abductor pollicis brevis (abp) with different levels of maximum voluntary contraction (mvc) (10100%). in order to analyze the collected emg and force data, the mean absolute value of each trial is calculated followed by a calculation of the average of the 3 trials for each grip for each subject across the different mvc levels utilized in the study. then, the mean and the standard deviation (sd) across all participants (3 males and 2 females) are calculated for fcr, fds and apb muscles with multiple % mvc, i.e 10, 30, 50, 70 % mvc for each gesture. the results showed that apb muscle has the highest mean emg activity across all grips, followed by fcr muscle. furthermore, the grip with the thumb and middle fingers is the grip with the highest emg activity for 10-70% mvc than the power grip. as for the 100% mvc, thumb and middle fingers grip achieved the highest emg activity for apb muscle, while the power grip has the highest emg activity for both fcr and fds muscles. keywords: electromyogram (emg), hand grip force, myotrace 400, maximum voluntary contraction (mvc), hand dynamometer. 1. introduction electromyogram (emg) signals from the skin surface are considered as a source of neural control information and are traditionally employed as inputs to the controller of upper-limb prosthetic hands [1], helping disabled people to use the remaining parts of their own forearm/hand to accomplish the activities of daily livings (adls) [2]. the term emg has been also associated with the process of detecting, recording, and evaluating the action potential produced by the muscles of the body [3], denoted as electromyography. the central nervous system (cns) is the origin of emg action potential by which the motor neurons carry the information transferred along the nerve in pulse repetition or known as frequency [3]. the action potential is generated by the flow of ions through the muscle fibers’ membrane, which spreads across the a. buniya al-khwarizmi engineering journal, vol. 16, no. 2, p.p. 1423 (2020) 15 interfacing tissues to reach the electrode detection surface placed on the skin [1]. surface emg electrodes are placed on the skin above the muscle of interest to measure the emg signal. surface emg is widely used as a non-invasive method to map the relationship between electrical activity of the muscles and the generated muscle force. therefore, the estimation of the hand force by using the semg signal is very essential in many applications such as design and control of a cybernetic prosthetics, sport medicine, medical rehabilitation, clinical diagnostics, kinesiology and biomechanics [3,4,5]. however, the number of muscles of interest, emg needed channels, the number and location of surface electrodes and type of gestures can all affect the relationship between muscle force and muscle activity [7,8]. daud et.al [3] studied the effect of two adjacent muscles on finger pinch and hand grip force. the muscles were two adjacent flexor muscles: flexor digitorum superficial (fds) and flexor carpi radialis (fcr), two adjacent extensor muscles: extensor carpi radialis longus (ecrl) and extensor digitorum communis (edc). nine subjects (seven males and two females) were chosen to perform seven types of hand movements with different percentage of mvc. despite the promising results of that study, they concluded that using a single muscle channel instead of adjacent muscles could provide an optimized data for pattern recognition or classification. the relation of emg signal to hand grip force at varying wrist angles had been studied by sidek et al [4]; in this study, the authors investigated the relationship between forearm emg, hand grip force, and wrist angles recorded by surface electrodes located on fcr, fds; and eds muscles. mvc range was 2 to 30% and recorded with 90 o , 60 o and 120 o degrees of wrist angle. however, the research focused only on the effect of change in angle of the wrist without using any other hand grip gestures. the hand force and emg signal are taken in consideration in some clinical implications and clinical issues. martin et al. [2] studied the quantification of six functional movements and acceleration which was measured in real time. six muscles were used to record the emg signals which showed that each muscle could have a different effect on hand gesture. li et al. [9] investigated the effect of diabetes mellitus on the dynamical coordination of hand intrinsic muscles during precision grip. the test was done using a costume design apparatus with stable and unstable loads. the emg signal was recorded from abductor pollicis brevis (apb) and first dorsal interosseous (fdi). to the best of our knowledge, only power grip was investigated with emg recorded from different muscles, with different %mvc, while no other types of grips were considered, such as the fine pinch or tripod grip. in this study, we investigate the emg activity of fine pinch, tripod grip and grip with the middle and thumb finger, as well as the power grip. the main aim of this study is to investigate the relationship between emg signal recorded from 3 muscles namely, fcr, fds and, apb; and four different hand grips under different %mvc (10100%). 2. methodology 2.1 participants in this study, five healthy subjects (three males and two females) aged between 30-40 years old (as illustrated in table 1) are recruited to perform several finger pinches and hand grasping movements. subjects provided informed consent before participating in the experiments. the subjects are clearly indicated with no muscle disorder or abnormal limbs. the data have collected at the university of baghdad, alkhwarizmi college of engineering. the participants sat on a chair in front of a battery powered computer with myotrace 400 (noraxon, usa). the raw signals and force power are displayed on computer to help the subject to perform the hand movement with the necessary mvc contractions. the experimental protocol has been done according to the deceleration of helsinki and its later amendments. table 1, a. buniya al-khwarizmi engineering journal, vol. 16, no. 2, p.p. 1423 (2020) 16 characteristics of the participants of the study. participant id gender age height neuromuscular disease con1 male 33 168 none con2 male 38 170 none con3 female 32 161 none con4 female 37 158 none con5 male 33 168 none 2.2 electrodes position the skin of the subject is cleaned and prepared with abrasive skin preparation gel (neuroprep, usa). six pairs of ag/agcl electrodes are placed at the center area of each muscle and the elbow joint is used as reference to mark the electrode locations. figure 1 shows the location of each electrode for all muscles. fig. 1.surface electrode locations on each muscle. 1. flexor carpi radialis (fcr), 2. flexor digitorum superficialis (fds), and 3. abductor pollicis brevis (abp). 2.3 signal acquisition myotrace 400 (noraxon, usa) data acquisition system has been used to record all data. the system has four channels, three channels for emg signals and one for vernier hand dynamometer (vernier, usa) which is used to record hand grip force and pinch force. the signals are sampled at a rate of 1000 hz with 16bit resolution data acquisition. all channels have a low pass anti-alias filter set to 500 hz. figure 2 shows the apparatus that was used to measure emg and hand grip force. fig. 2. emg and hand grip force measurement experimental setup, computer laptop, data acquisition (daq) device with myotrace 400, and vernier hand dynamometer 2.4 experimental protocol four different grip patterns are investigated in this work as shown in figure 3: 1) fine pinch with thumb and index fingers, 2) tripod with thumb, index and middle fingers, 3) thumb middle pinch with thumb and middle fingers, and 4) power grip. emg signals are recorded using surface electrode arrays from flexor carpi radialis (fcr), flexor digitorum superficialis (fds), and abductor pollicis brevis (abp) muscles. each hand movement has three trials record while each motion is sustained for a period of 6 seconds only with 6 seconds resting period given between motions. each subject has asked to perform maximum voluntary contraction (mvc) during recording, then has to perform different percentage of mvc (10%, 30%, 50%, 70%, and 100%). a. buniya al-khwarizmi engineering journal, vol. 16, no. 2, p.p. 1423 (2020) 17 fig. 3. four types of hand movements: 1. fine pinch with thumb and index fingers. 2. tripod with thumb, index and middle fingers. 3. thumb middle pinch with thumb and middle fingers. 4. power grip. 2.5 data analysis data have recorded from three forearm muscles (fcr, fds, and abp) of five subjects, with each subject performing four hand and finger gestures with multiple levels of %mvc (i.e.,10,30,50,70, and 100 % mvc). in order to analyze the collected emg and force data, we have utilize the mean of absolute value (eq. 1) for each trial and then calculate the average of the three trials of each grip for each subject with different % mvc levels. then, the mean and standard deviation (sd) across all participants (three males and two females) are calculated for fcr, fds and, apb muscles with multiple % mvc, i.e 10, 30, 50, 70 % mvc for each gesture as will be presented in section 3. as for the 100% mvc, the mean of the absolute value across the two recorded trials are calculated across three subjects as well as the sd as shown in section #. mean of the absolute value = � � ∑ |��| � ��� …(1) where n is the number of samples in the trial, xn is the emg sample of position n in the trial. 2.6 statistical analysis in the last part of the data analysis, we evaluate the statistical significance of the achieved results using an n-way analysis of variance (anova) with three grouping variables (factors): the different mvc levels (10, 30, 50, 70 and 100%), the different types of grips (fine pinch, tripod grip, grip with thumb+middle, and power grip), and the different muscles considered (apb, fds, and fcr). we also have teste the two-factor interactions, with the interaction terms being represented by mvc levels*type of grips, mvc levels*the different muscles, and types of grips*the different muscles in the anova table. the significance level for confidence bounds in the above analysis has set to 0.05. a p-value that is smaller than the significance level of 0.05 indicates that the mean responses for the different levels of the considered factor(s) are significantly different. a. buniya al-khwarizmi engineering journal, vol. 16, no. 2, p.p. 1423 (2020) 18 3. results and discussion in figure 4, three trials of emg signal for three fcr, fds and apb muscles are shown with the force measurement for power grip gesture at 50 % mvc for participant 1 whereas figure 5 shows the same plots but for tripod grip with 30 % mvc for participant 2. in both figures, emg activity of apb seems to be higher than that of fcr and fds for both participants. similar trend can be observed in figure 6 for female participant for fine pinch movement with 70% mvc. it can be also noted from the force plots in the bottom figures 4, 5, 6 that there are little variations between the force measurements produced by the participants across the three trials. fig. 4. a plot of the emg for the power grip with 50% mvc for participant 1 (male participant). the top 3 figures represent the 3 trials of emg from the fcr, fds and apb, respectively. the bottom figure is the force signal measured in newton with hand dynamometer. fig. 5. a plot of the emg for the tripod grip with 30% mvc for participant 2 (male participant). the top 3 figures represent the 3 trials of emg from the fcr, fds and apb, respectively. the bottom figure is the force signal measured in newton with hand dynamometer. a. buniya al-khwarizmi engineering journal, vol. 16, no. 2, p.p. 1423 (2020) 19 fig. 6. a plot of the emg for the fine pinch with 70% mvc for participant 3 (female participant). the top 3 figures represent the 3 trials of emg from the fcr, fds and apb, respectively. the bottom figure is the force signal measured in newton with hand dynamometer table 2 illustrates the mean values of the emg and standard for five participants for three muscles with four types of grips for 10% mvc. the grips with the thumb and middle finger have the highest mean of the emg activity 25.8 uv compared to other grips. additionally, apb is the muscle with the highest activity across all group types where mean activity is equal to 45 uv. it should be noted that abp is an extrinsic muscle which lies inside the hand compared to fcr and fds that are external actuators of the finger and the wrist located on the forearm. the standard deviation for the apb is higher than that of fcr and fds muscles since the subject emg activity has more variability for apb muscle than other muscles, i.e. fcr and fds. table 2, mean values of emg activity (mean ± sd) in in (µv) of different grips types for the case of 10% mvc for 5 subjects for fcr, fds and apb muscles. fcr fds apb mean fine pinch 5.1 ± 1.3 5.1 ± 2.5 33.2 ± 20 14.4 tripod grip 5.8 ± 1.5 5.4 ± 2 39.3 ± 20.6 16.8 grip with thumb+middle 7.3 ± 3.7 6.1 ± 2.8 64.1 ± 37.9 25.8 power grip 8.4 ± 2.2 10.5 ±1.8 43.3 ± 19.5 20.7 mean 6.6 6.8 45.0 table 3, table 4, and table 5 illustrate the results of the mean of the emg activity, for the three muscles with different types of grips investigated in this study, for 30% mvc, 50% mvc, and 70% mvc respectively. from table 2, table 3 and table 4, it is noteworthy to mention that the grip with the thumb and middle fingers has the highest emg activity compared to other grips for 30%, 50% and 70% mvc. furthermore, the emg activity from apb muscle is the highest for 30%, 50 % a. buniya al-khwarizmi engineering journal, vol. 16, no. 2, p.p. 1423 (2020) 20 and 70 mvc similar to that of 10% mvc illustrated in table 1. as for fds muscle, 30, 50, 70% mvc, the power grip is the grip with the highest emg activity as the main finger flexor is fds located on the forearm. table 3, mean values of emg activity (mean ± sd) in in (µv) of different grips types for the case of 30% mvc for 5 subjects for fcr, fds and apb muscles. fcr fds apb mean fine pinch 5.9 ± 2.2 6.7 ± 2.5 38.2 ± 25.9 16.9 tripod grip 7.5 ± 2.8 7.4 ± 1.9 57.7 ± 30.1 24.2 grip with thumb+middle 14.1 ± 10.5 10.0 ± 5.3 95.9 ± 59.4 40.0 power grip 14.4 ± 3 22.2 ± 6.5 70.2 ± 34.1 35.6 mean 10.5 11.6 65.5 table 4, mean values of emg activity (mean ± sd) in in (µv) of different grips types for the case of 50% mvc for 5 subjects for fcr, fds and apb muscles. fcr fds apb mean fine pinch 9.2 ± 4.7 12.1 ± 9.4 55.6 ± 29.7 25.7 tripod grip 10.8 ± 5.6 10.1 ± 3.3 87.0 ± 54.1 36.0 grip with thumb+middle 23.7 ± 19.2 20.1 ± 10 172.7 ± 94.1 72.2 power grip 23.6 ± 8.9 36.6 ± 16.1 86.7 ± 35.3 49.0 mean 16.8 19.7 100.5 table 5, mean values of emg activity (mean ± sd) in in (µv) of different grips types for the case of 70% mvc for 5 subjects for fcr, fds and apb muscles. fcr fds apb mean fine pinch 13.2 ± 5.3 19.4 ± 15 99.5 ± 48.3 44.1 tripod grip 17.4 ± 9.5 15.7 ± 7.7 120.9 ± 56.3 51.4 grip with thumb+middle 29.4 ± 15 31.1 ±16.8 241.3 ± 145.4 100.6 power grip 35.3 ± 13.3 56.2 ± 21.8 113.0 ± 61.5 68.1 mean 23.8 30.6 143.7 figure 7 show the mean of the absolute value of the emg activity for the three muscles of different grips for 100% mvc. standard deviation across five subjects is illustrated with error bars. the grip with the thumb and middle fingers has the highest activity for apb muscle, while the power grip has the highest activity in both the fcr and fds muscles. a. buniya al-khwarizmi engineering journal, vol. 16, no. 2, p.p. 1423 (2020) 21 fig. 7: mean of the absolute value of emg for 3 muscles for different grip types (fine, tripod, grip with thumb and middle fingers and power grip) for 100% mvc. error bars represent standard deviation across the 5 subjects. figure 8 shows the mean value of the recorded force with hand dynamometer in newton (n) for all subjects for different grip patterns with 10, 30, 50, 70, and 100% mvc. the mean is calculated across all trials, grip types and subjects. the measured force of contraction increases as the % mvc increases for all grip patterns as seen in figure 4. this clearly shows the high accuracy of the recording protocol to measure the correct level of the %mvc for all subjects. fig. 8. mean of the force measurements in newton (n) for 5 subjects with different grips for different levels of %mvc (i.e. 10, 30, 50, 70 and 100% mvc). in the final part of the experimental results we analyzed the data statistically using n-way anova. the resulting anova table revealed that, across each of the considered factors or simply the main effects, the mean values of the emg signals are significantly different across the different %mvc levels (p-value ≤ 0.001), the different muscles (p-value ≤ 0.001) and across the different hand grips (p-value ≤ 0.001). however, testing the two-factor interactions revealed no evidence of statistically significant interaction between the different %mvc levels and the different hand grips (p-value = 0.594) as the generated force increased with changing the %mvc, but the generated patterns of force levels across the different grips are consistent as shown in figure 4. on the other hand, significant interactions are observed between the %mvc levels and the different muscles (p-value ≤ 0.001) and between the different hand grips and the different muscles (p-value ≤ 0.001). this is in turn justified as the mean values of the emg signals a. buniya al-khwarizmi engineering journal, vol. 16, no. 2, p.p. 1423 (2020) 22 changed more significantly with the different %mvc levels and the different muscles involved than that with the different hand grips. the results of the current study may be compared to the study of martin et al. [2], where the researchers had been studied the quantification of six functional movements and acceleration which was measured in real time. the grip and pinch movements were terminal pinch, terminolateral pinch, tripod pinch, power grip, extension grip and ball grip while the emg signals recorded from six muscles. they obtained that the spherical grip had greater electrical activity and the muscle with the highest record was the thenar region. in our study, we have investigated different muscles under different levels of % mvc and obtained that apb muscle has the highest mean emg activity across all grips, followed by fcr muscle. furthermore, the grip with the thumb and middle fingers is the grip with the highest emg activity for 10-70% mvc, then the power grip. as for the 100% mvc, thumb and middle fingers’ grip achieved the highest emg activity for apb muscle, while the power grip has the highest emg activity for both fcr and fds muscles. the major limitation of our study is the small sample size of the participants. as a future goal, more participants will be recruited to increase the reliability of the study. in addition to that, we are planning to record emg signal from different muscles with different hand gestures to find out the relation between emg signal and muscle force with different % mvc. 4. conclusion in this paper, we investigated, with the use of hand dynamometer, the quantification of emg activity for different types of grips for three muscles: fcr, fds, and apb under different %mvc levels (i.e. 10, 30, 50, 70 and 100 %mvc). analysis of the mean absolute value of the emg activity for all trials, muscles, grip types, and subjects showed that for (10 70) % mvc, apb has the highest mean emg activity across all grips, followed by the fcr muscle. in addition, grip with the thumb and middle fingers is the grip which has the highest emg activity for (10-70) % mvc, followed by the power grip. as for the 100% mvc, the grip with the thumb and middle fingers has the highest activity for apb muscle, while the power grip has the highest emg activity for both the fcr and fds muscles. abp muscle, an intrinsic muscle in the hand, may be used for rehabilitation applications, while fcr can be a good candidate to target the forearm muscles. as for the grip selection, grip with the thumb and middle fingers is the grip with the highest emg activity then the power grip comes in the second place. 5. references [1] a. h. ali, “an investigation of electromyographic (emg) control of dextrous hand prostheses for transradial amputees,” ph.d dessertation, school of computing and mathematics faculty, plymouth university, 2013. [2] j. martin-martin and a. i. cuesta-vargas, “quantification of functional hand grip using electromyography and inertial sensor-derived accelerations: clinical implications,” biomed. eng. online, vol. 13, no. 1, p. 161, 2014. [3] w. m. b. wan daud, n. abas, and m. o. tokhi, “effect of two adjacent muscles of flexor and extensor on finger pinch and hand grip force,” 2018 5th int. conf. control. decis. inf. technol. codit 2018, no. april, pp. 140–145, 2018. [4] s. n. sidek and a. j. haja mohideen, “mapping of emg signal to hand grip force at varying wrist angles,” 2012 ieee-embs conf. biomed. eng. sci. iecbes 2012, no. december, pp. 648–653, 2012. [5] g. hajian, e. morin, and a. etemad, “emgbased force estimation using artificial neural networks emg-based force estimation using artificial neural networks,” no. may, 2019. [6] g. hajian, e. morin, and a. etemad, “pcabased channel selection in high-density emg for improving force estimation,” no. july, pp. 652–655, 2019. [7] n. h. gheab and s. n. saleem, “comparison study of electromyography using wavelet and neural network ,” al-khwarizmi eng. j., vol. 4, no. 3, pp. 108–119, 2008. [8] m. k. sabir and n. k. muhsin, “an autocorrelative approach for emg timefrequency analysis,” kecbujournal.com, vol. 9, no. 1, pp. 39–46, 2013. [9] k. li, n. wei, m. cheng, x. hou, and j. song, “dynamical coordination of hand intrinsic muscles for precision grip in diabetes mellitus,” sci. rep., vol. 8, no. 1, pp. 1–13, 2018. )2020( 1423، <=>1 2ا/;3د، 316-*1 ا/78ارز&( ا/4#23"1 ا/.-*& ,+*( )'&% $#" 23 d>*"% اp.'ط &1amn/ 1=*o8 ا/"3 و اi+ j$'>k طcd efg-"% اb'رات ا/;a@ت و 4s'ز &n"'س 1amq ا/"3 ,"#$ %&'( )*+* ).".o/ا i"ct )*+** ء أk7د.<& w;#./3اm+*** ,$'b7x )&را**** ij:اد efg8 ھ;:89 اbc7 اa7=.@1 / ?<=8 ا7>;:89 ا567ارز-1 / /.-,*،**،*** ****1k:9 8,-./ /8=l=mcn75@.ت اjوq>7 17اqn9rا s?qt7ا7=.اqn91 / اk:=9 / :1kوqnv7rا :wqm7ا*alikamil85@kecbu.uobaghdad.edu.iq **:wqm71: اkوqnv7rا ali.altimemy@kecbu.uobaghdad.edu.iq ***:wqm71: اkوqnv7rاalaaaldoori@kecbu.uobaghdad.edu.iq ****:wqm71 اkوqnv7rا: rami.khushaba@sydney.edu.au ا/8@<1 ) 8=x.jq<v7ت اyz,7ا\.رة ا ]=^f@ qmn,wemg 8 و>z,76=` _.87 اan7 8=9.9rق اqc7ا c(.wy67ت اyz,7ا\.رة ا d-:6n98. ا=?qa78 ا=mf,7ا ) 8=x.jq<v7اemg 6.ص\rة ا:h.ft7 8=h.;f7اف اqطrا k>h ةqc=f>7 ر:ft? (ز.^kl 8m>n6ط.tkدرا89 ا n7ذ p-ة ا7=5-=8. و.=a78 اcakت ا.zmg c5-.g q=_ 8 ا\6.صryr k>h 89اء ا7:راq/ا e@ .ت.w:an7ا eاھ cوا_:ة qmn,@ 8=x.jq<v7ت اyz,7ط ا\.رة ا.ak p8gy,7د ا.^wاءا ا7=: و اq/tj pjار ) 8m>n6ت.?q_fine pinch, tripod grip and grip with the middle and thumb finger, as well as the power grip 6:ام />.زn9ا e@ .( l-flexor carpi radialis (fcr), flexor digitorum superficialis (fds)=.س 8zmg اv ]=^fn7 :=7,.7=8 اyz,7ت -yzh 8ryr cت وھ1 ( and abductor pollicis brevis (abp)8m>n65ىg ت.w5nftj ( ١٠٠-١٠% mvc ب.f_ e@ 8>^ft7ت ا.k.=m7ا p=t/ ]=>a@ ]/ا c. 8t=l795| اnrل و ا:,t7ب ا.f_ e@ er c-8. وm>n65ةg ت.w5nft7 `6\ ]v7 8 وzmg ]v7 8ry~7ت اrو.at>7 ل:,t7ب ا.f_ e@ .ھ:,j 87و.a]v7 8l>ct7اف اqak ) 8m>n65ةg ت.w5nftj 8>zh ]v7 c=?ر.at76.ص ا\rا ]v7 ري.=,t7٧٠، ٥٠، ٣٠، ١٠ا %mvc( ا �x.n;7ت اq<اظ :g8. و?q_ ]v7 ) 8>zh نapb ( ) 8>zh .<=>@ ت و.zml7ا ]v7 8=>zh 8=7.,v ل:,k>h7>. اfcr .(8v.ضl.j 8=7.,v k>hا n>t@ 1c957ا pm�rا pم.<jr8 ا?q_ ن.j �x.n;7ا d;=j n7ذ k7ا ) c5ةl>7 8=>zh٧٠-%١٠ %mvc) 8?q_ .<=>@ و (power grip 5ةl>7 8mf;7.j .-١٠٠). ا %mvc rم و ا.<jr8 ا?q_ k>hا d>^9 |9وrا pm� ) 8>z,7 8mf;7.j 8=>zh 8=7.,vapb) 8?q_ d>^9 .t;=j (power grip) تyz,7 8=>zh 8=7.,v k>hا (fcr and fds .( <4d6963726f736f667420576f7264202d2032332d3332e3cde3cf20c8d4edd120e6e6cfc7cf> al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 15, no. 4, december, (2019) p. p. 2332 free vibration analysis of laminated composite plates with general boundary elastic supports under initial thermal load mohammed b. hammed* widad i. majeed** ***department of mechanical engineering/ university of baghdad *email: mohammed88alabas@gmail.com **email: wedad.ibrahim@coeg.uobaghdad.edu.iq (received 21 may 2019; accepted 3 september 2019) https://doi.org/10.22153/kej.2019.09.004 abstract free vibration behavior was developed under the ratio of critical buckling temperature of laminated composite thin plates with the general elastic boundary condition. the equations of motion were found based on classical laminated plate theory (clpt) while the solution functions consists of trigonometric function and a continuous function that is added to guarantee the sufficient smoother of the so-named remaining displacement function at the boundaries, in this research, a modified fourier series were used, a generalized procedure solution was developed using ritz method combined with the imaginary spring technique. the influences of many design parameters such as angles of layers, aspect ratio, thickness ratio, and ratio of initial inplane thermal load in addition to different boundary conditions on the natural frequencies of laminated plate is analyzed. in general, the changes of fundamental natural frequency is inversely proportional with the ratio of thermal buckling load, also most parameters aspect ratio effect on the natural frequency about 35 – 40%. the present results were compared with those obtained by other researchers, and show good agreement. keywords: thermal buckling, laminated composite plate, general boundary condition, ritz method. 1. introduction composite materials are widely employed in many engineering disciplines applications in mechanical and civil engineering. many have been researching free vibration analysis under initial thermal load of laminated composite thin and thick plates, but the research has been focused on some problems that include a few forms of boundary conditions because the rectangular plates have 55 forms of boundary condition therefore the solution procedure becomes very tedious when use of mode shapes as the basis functions, that’s why the former researchers have been used at opposite edges of one pair of simply supported and clamped, so with general boundary conditions one may have to apply convergent methods like rayleigh-ritz, the chosen of suitable admissible functions is of high significance when applying the method of rayleigh-ritz due to precision of the results, many investigations are worked about thermal buckling of laminated plate by using classical laminated plate theory but no one studied effect of general boundary conditions analytically. random free vibrations under the thermal loading of laminated composite plates with all boundary conditions was studied at [1], the randomness in lamina coefficients of thermal expansion and material properties are taking into consideration. based on higher-order shear deformation theory the system equations have been derived, incorporating rotary inertia effects. for handling the random eigen value problem, the finite element method is applied. the research transacted for together numerical and experimental examinations of the free vibration behavior under different moisture and temperature of composite laminated plates presented at [9]. the governing equations have been found based on first-order mohammed b. hammed al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 2332 (2019) 24 shear deformation theory (fsdt) for the behavior structural of the composite laminated plates. quantitative results are shown to present the parameters’ influence of woven fiber laminate of (material, geometry, and lamination) on the free vibration of composite plates for varying moisture and temperature concentrations. the vibration and buckling of initially thermal stressed composite plates with material properties dependent on temperature was presented at [3]. using the variation method, the governing equations have been found including the transverse shear deformation influences. the influences of different parameters on the vibration and buckling behaviors of laminated plates are investigated with respect to the material properties that are dependent on temperature. the distribution temperature is supposed to be linear and uniform on the plate in the transverse direction. [15] focused on the vibro-acoustic response and buckling of the clamped laminated composite plate induced by a harmonic concentrated force in the thermal environment. for acoustic response and vibration, the analytical solution has been derived for a fully clamped boundary condition. meantime, the buckling temperatures and natural frequencies of the plate in the uniform temperature environment are also established by utilizing the first-order shear deformation theory (fosdt) and classical laminate theory (clt). [5] presented the influence of hydrothermal conditions such as moisture and temperature on buckling load and free vibration frequency of laminated composite plates. to determine the critical load of the plate, the finite strip method based on first-order shear deformation theory (fosdt) was applied to estimate the displacement field of each strip in the finite strip formulation. linear shape functions and the hermitian method were applied for in-plane and out–of–plane transverse direction and the trigonometric shape functions were applied in the longitudinal direction. the effect of a variable in material properties under different moisture and temperature on natural frequency and buckling capacity was estimated of plates with various biaxial loading and end conditions, as well as, the influence of the layer's delamination on natural frequency and buckling load of the plate was researched in various cases. [10] presented the modal analysis of composite laminated structures subjected to thermal effect. a green–lagrange nonlinear finite element (fe) model has been advanced according to the tsdt (third-order shear deformation theory) for the analysis. most of the research mentioned above has dealt with the composite plates within specific boundary condition, but in this research, we will deal with the general boundary condition of composite plates. the present work investigates the free vibration analysis under effect of critical buckling temperature of laminated composite thin plate with general boundary condition, based on classical laminated plate theory and using rayleigh–ritz method, the displacement function as fourier cosine series, plus, an arbitrary continuous function proposed by [15] for first time, so the effect of angle-ply orientation, boundary conditions, aspect ratio, and different composite materials properties are examined. 2. theoretical analysis 2.1 classical laminated plate theory governing differential equation of laminated thin plate based on classical laminated plate theory (clpt), for natural vibration under thermal buckling load is written as; [4]. d�� ∂�w∂x� + �2d� + 4d�� ∂�w∂x ∂y + d ∂�w∂x� + 4d � ∂�w∂x ∂y� + 4d�� ∂�w∂x� ∂y + n�� ∂ w∂x + n�� ∂ w∂y + 2n��� ∂ w∂x ∂y + i� ∂�w∂t = 0 … �2.1 {n�} = ! "a$ {α}& ∆t dz +, +,-. / &0� … �2.2 where: dij are bending stiffness, {α} is a vector of thermal expansion coefficient, [a] is the extension stiffness matrix, 1 is the frequency of the lamina vibrations. introducing the moment of the inertia �23 per unit area of the laminate at point (x, y); 23 = ! 4 56 758 9: = 4; < =0� �:; − :;7� … �2.3 where l: the total number of layers constructed the plate, k: denotes the layer number, h: the thickness of the lamina, :;, and :;7� : distances from the reference plane of the lamina to the two surfaces of the @a5 ply. in this study, uniform temperature distribution is taken into consideration. mohammed b. hammed al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 2332 (2019) 25 2.2 total mechanical energy the definition of the total mechanical energy is the aggregation of its kinetic energy and potential energy of a particles being applied on by only conservatively by constant forces [11]. b = c − bd = efghijgi … �2.4 where e: total mechanical energy of a system, ec: total kinetic energy of the system, π: total strain energy of the system. potential energy of purely bending plate under in plane thermal load is [14]; c = 12 ! ! kl�� mn 1no p + l mn 1nq p r � s � + l�� m2n 1nonqp + 2 ml� n 1no n 1nq pt 9o 9q + 12 ! u@v�1 + wv� xn1no y zv0� 9qs � + 12 ! u@v�1 + wv� xn1nq y zv0r 9qs � + 12 ! u@[�1 + w[� xn1nq y z[0� 9or � + 12 ! u@[�1 + w[� xn1nq y z[0s 9o r � − 12 ! ! u\v] xn1no y + \[] xn1nq y r � s � + 2\v[] m n 1nonqpz 9o 9q … �2.5 ∆e=0 or e= constant … �2.6 bd = 12 ` a 2313 9o 9q … �2.7 2.3 boundary conditions the twisting and bending shear forces can be expressed in displacement function as; [4]. cv = −l�� n 1no − l� n 1nq … �2.8 c[ = −l n 1nq − l� n 1no … �2.9 cv[ = −2l�� n 1nonq … �2.10 fv = −l�� n�1no� − �l� + 4l�� n�1nq no … �2.11 f[ = −l n�1nq� − �l� + 4l�� n�1no nq … �2.12 for rectangular plate restrained elastically, the boundary conditions are: @v�1 = fv wv� n1no = −cv ji o = 0 … �2.13 @v�1 = −fv wv� n1no = cv ji o = j … �2.14 @[�1 = f[ w[� n1nq = −c[ ji q = 0 … �2.15 @[�1 = −f[ w[� n1nq = c[ ji q = g … �2.16 fig. 1. a rectangular plate elastically restrained along edges, [15]. where, w[�, w[� jg9 wv�, wv� are the stiffness of the rotational spring, @[�‚ @[� jg9 @v�‚ @v� are the stiffness of the transitional spring, ji q =0 jg9 g�o = 0 jg9 j respectively. eqs. (13) (16) shows a set of different b.cs from which, the free boundary condition can be found by setting the spring constant to zero while setting the spring constant to infinity the clamped condition can be obtained (in actual calculation as a large number) and the simply supported can be obtained by setting the spring constant larger than zero and smaller than ∞ (0 < k < ∞), see (fig. 1). from eq. (8)-(16), the boundary conditions can be finally expressed as; @v�1 = −l�� n�1no� − �l� + 4l�� n�1nq no … �2.17 @v�1 = l�� n�1no� + �l� + 4l�� n�1nq no … �2.18 wv� n1no = l�� n 1no + l� n 1nq … �2.19 wv� n1no = −l�� n 1no + l� n 1nq … �2.20 mohammed b. hammed al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 2332 (2019) 26 2.4 admissible functions the permissible functions take a significant role in the rayleigh-ritz technique. the beam functions products are orderly selected as the permissible functions and the displacement function can be written as; [15] 1�o‚q = ∑ klmnl�o om�q �2.21 l‚m0� where nl�o , or om�q , is the characteristic beams functions contain the same b.cs in the xdirection and y-direction, sequentially. as a linear collection of trigonometric and hyperbolic functions, the functions of the beam can be broadly acquired, they contain a few unknown parameters and from which the boundary conditions are obtained. accordingly, then, all boundary conditions essentially derived to various forms of beam functions. in veritable employment, this is plainly inappropriate, for a various boundary beam. an advanced method of fourier series has been suggested for beams with a qualitative boundary at ends so as to avoid this obstacle, in which the characteristic functions are express in the term of; [19]. 1�o = jl cos srlo + t�o u l0� vsrl = wxj y ‚0 ≤ o ≤ j. … �2.22 where p(x) can be a count a qualitative continuous function that, whatever of b.cs, is permanently elected to accept the subsequent equations [9]: {|||�0 = }|||�0 = ~� … �2.23 {|||�j = }|||�j = ~� … �2.24 {|�0 = }|�0 = �� … �2.25 {|�j = }|�j = �� … �2.26 still, as a continuous function that accepts eq. (2.23)-(2.26), p(x) formula doesn’t consider the convergence of the series of the solution. so, the p(x) function can be an option in different desired shape. as shown, postulate that p(x) is a polynomial function, {�o = em {m vojy … �2.27 � m0� where {m�o is the legendre function em is the expansion constant of order n, the above expression for the function p(x) can be express as; p�x = �r�o ]�� … �2.28 where �� = {~�‚~�‚��‚��}] … . �2.29 and �r�o ] = ⎩⎪⎪ ⎨ ⎪⎪⎧− ���v�7��rv����r�v�7�r�����r���v�7��r�v���r�����r��rv7 r�7�v���r��v�7r���r ⎭⎪⎪ ⎬ ⎪⎪⎫ …�2.30 the results in eq. (2.28)-(2.30) are obtained from much more direct but general approaches, [15]. so as to find the unknown constants of boundary, ~�‚~�‚��‚ and ��, substitution of eq. (2.22) and (2.28) into the boundary conditions eq. (2.17)(2.20) results in: �� = �r7�frljl u l0� … �2.31 where �r = ⎣⎢ ⎢⎢ ⎢⎢ ⎢⎢ ⎡1 + 8@v�j� 360l��7@v�j� 360l�� j3 j6 7@v�j� 360l�� 1 + 8@v�j� 360l��j6 j3 −@v�j3l��−@v�j3l��wv�l�� + 1j−1j −@v�j6−@v�j6−1j wv�l�� + 1j ⎦⎥ ⎥⎥ ⎥⎥ ⎥⎥ ⎤ … �2.32 and frl = ¤�−1 @v�l�� �−1 l @v�l�� − srl �−1 lsrl ¥ ] … �2.33 for a totally free beam, it must be reminded that a matrix ha becomes single. via, this case can be controlled to a few extension by imaginary deliver springs to the edges of a beam with the littlest stiffness. it has been exhibited in [19]. in such remediation via the matrix might be unconditional. although, the functions are much more appropriate for a specific condition and can be instantly applied in the method of rayleigh-ritz as the permissible functions. by applying eqs. (2.28) and (2.31), eq. (2.22) can be expressed as 1�o = jl¦lr �o u l0� … �2.34 where ¦lr �o = cos srlo+ �r�o �r7�frl … �2.35 mathematically, eq. (2.34) suggests that all of the functions of the beam shown as a function in the practical area with the principal functions {¦lr �o : w = 0‚ 1‚ 2‚ … … … }. therefore, eq. (2.21) expressed as: mohammed b. hammed al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 2332 (2019) 27 1�o‚q = klm¦lr �o ¦ms�q u l,m0� … �2.36 where ¦ms�q = cos ssmq + �s�q �s7�fsm … �2.37 the terms for �s�q ‚�s jg9 fsm can be, correspondingly, found from eqs. (2.30), (2.32) and (2.33) by little shifting the xconcerning parameters by the yconcerning. 2.5 determination of the natural frequency under in-plane thermal buckling load substituting eqs. (2.5) and (2.7) in eq. (2.4), the total mechanical energy can be written in the following expressions: b = 12 ! ! kl�� mn 1no p + l mn 1nq p r � s � + l�� m2n 1nonq p + 2 ml� n 1no n 1nq pt 9o 9q + 12 ! u@v�1 + wv� xn1no y zv0� 9qs � + 12 ! u@v�1 + wv� xn1nq y zv0r 9qs � + 12 ! u@[�1 + w[� xn1nq y z[0� 9or � + 12 ! u@[�1 + w[� xn1nq y z[0s 9o r � − 12 ! ! u\v] xn1no y + \[] xn1nq y z 9o 9qr � s �− 12 ` a 231 9o 9q … �2.38 where the transverse displacement (13 is substituted as mentioned in section (2.4). to calculate the natural frequency under in plane thermal buckling load action; \v] is left as a known ratio of the critical thermal buckling load \d]̈ . performing the required mathematical processes (integrations and differentiations) of eq. (2.38) and using ritz method we get: nbnklm = 0 … �2.39 eq. (2.39) gives homogenous equations as follow: ©�klm‚\vv] ‚`�= 0 ©fª «¬gªji¬fg ­g9®ª ¬gi¬j¯ iℎ®ªwj¯ hiª®hh … �2.40 solving eq. (2.40) as an eigen-value problem which is written as below: k j�‚� ⋯ j�‚�l∗m ⋮ ⋱ ⋮j�l∗m ‚� ⋯ j�l∗m ‚�l∗m t µ k��⋮klm ¶ = 0 …�2.41 where j·¸ are the coefficients of the nonzero unknowns klm. finding the determinant of the first term of eq. (2.41) and equating it to zero will lead to get the natural frequencies ` under intial thermal stress \d]̈ when m and n are more than 1, the natural frequencies ` under intial thermal stress \d]̈ is determined by solving the eigen value problem. for different edge conditions and m and n greater than 1, the solution becomes more difficult and needs computer programming to find natural frequencies. in this study matlab r2017b is used to numerically solve the eigen value problem to find the natural frequency under thermal buckling action. 3. numerical result the natural frequency under the ratio of thermal buckling of composite laminated plate with the general elastic boundary condition is analyzed and solved using matlab r2017b. to verify the derived equations and performance of computer programming for vibration analysis of composite laminated plate, the numerical results of composite laminated plate were compared with those obtained by other researchers and those obtained by numerical program ansys. the frequencies are investigated with the effect of the in-plane thermal loading which is ratio of critical thermal buckling load. several considerations are presented to investigate the frequency. in case of in-plane action, a ratio (d) of critical thermal load is applied. the effective ratio (d) is studied to present the behavior of the plate and its frequency. the dimensionless fundamental frequency for all edges simply supported symmetric cross-ply [0/90/0] square plates under two sets of thermal loading conditions with various side-to thickness ratios are obtained and presented in table 1 along with those available in the [1], used a finite element method based on higher order shear deformation theory. from the table, as expected natural frequencies decrease with increasing temperature and thickness ratio due to reduced plate stiffness it can also be seen that the present results are in good agreement. the material properties are: mohammed b. hammed al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 2332 (2019) 28 table 1, dimensionless first mode frequency�¼� = ¼½¾¿àáâ ã¿⁄ å⁄ �, for [0 90 0] plates under different load temperature) also obtained natural frequencies under different load temperature are compared with the results that obtained by [17], which they applied the classical laminate theory (clt) and first order shear deformation theory (fosdt) as listed in table 2. as expected natural frequencies decrease as the temperature increase due to reduction of plate stiffness, a rectangular laminated plate with dimensions 600 × 400 × 5 mm3 is considered. the plate is composed of five layers with equal thickness. the orientations of the layer are [0/90/0/90/0], it can also be seen that the present results are close to results from ref. [17]. the material property of each single layer is: table 2, comparisons of natural frequencies (hz) at different temperatures, δtcr=95.124. fundamental natural frequency of square plates with various boundary conditions under different thermal buckling load ratio (d), is calculated and listed in tables 3 and 4 for symmetric cross laminated plates and anti-symmetric angle ply which give small error when compared with results obtained by numerical program ansys. stiffness of the plate with the clamped along two or four edges was greater than any other boundaries, therefore it vibrates with a higher frequency. in other hand, the frequency of the sfsf plate is minimal due to low stiffness. it is clear that the frequency was less than frequency that found without loading because of the reduced stiffness due to thermal loading. the aspect and modulus ratios schemes of laminated plate for simply supported are changed in table 5, the results of the frequency under thermal load ratio (d=0.5) and compared with those obtained by numerical program ansys, it can be noted that the frequency decreases with increasing the aspect and increases when the modulus ratio increases, due to stiffness changes. figure (2), shows the first four mode shapes of the laminated plate for cfff symmetric cross ply in the reference temperature environment of the same materials properties in tables 3 and 5. e1 e2 g13=g12 g23 40*e2 6.92gpa 0.6*e2 0.5*e2 12v α1 α2 0.25 1.14*10-6/0k 11.4*10-6/0k discrepancy % [1] present temp. a/h=50 a/h=20 a/h=50 a/h=20 a/h=50 δtcr=223.451 a/h=20 δtcr=1401.64 0.656 7.077 18.7871 17.483 18.9 18.8145 0 11.234 5.5534 16.2855 17.172 14.456 18.1817 100 e1 e2 g13=g12 g23 132gpa 10.3gpa 6.5gpa 3.91gpa v12 α1 α2 ρ 0.3 1.2*106/0c 2.4*106/0c 1570 kg/m3 80 60 40 20 0 temp 82.46 123.6 154.131 179.54 201.65 present 66.1 116.19 149.89 176.91 200.02 [17] 19.84 6 2.75 1.465 0.81 discrepancy % mohammed b. hammed al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 2332 (2019) 29 table 3, dimensionless first mode frequency�¼� = ¼½¾¿àáâ ã¿⁄ å⁄ �, for [0 90 90 0] plates under different load ratios of critical buckling temperature for different boundary conditions, (ãæ ã¿⁄ = æç‚ èæ¿ = é. çã¿ ‚è¿ê =é. êêçëã¿‚ìæ¿ = é. ê‚ �æ = é. éæçí − ë‚ �¿ = æí − ë ¾ = î‚ ¾å = æéé . table 4, dimensionless first mode frequency�¼� = ¼½¾¿àáâ ã¿⁄ å⁄ �, for [30/-30]4 plates under different load ratios of critical buckling temperature, (ãæ ã¿⁄ = æç‚ èæ¿ = é. çã¿‚ è¿ê = é. êêçëã¿‚ìæ¿ = é. ê‚ �æ = é. éæçí − ë‚ �¿ =æí − ë ‚¾ = î‚ ¾å = æéé . table 5, dimensionless first mode frequency �¼� = ¼½¾¿àáâ ã¿⁄ å⁄ �, for [0 90 90 0] (ssss) plates with effect of aspect and modulus ratios, (èæ¿ = é. çã¿‚ è¿ê = é. êêçëã¿‚ìæ¿ = é. ê‚ �æ = é. éæçí − ë‚ �¿ = æí − ë ‚ ¾å = æéé natural frequency under load ratios of critical buckling temperature d=0.5). d references cccc ssss scsc cccf sssf sfsf cfcf 0 matlab 26.4 15.53 24.26 12 6.87 4.1 9.283 ansys 25.63 15.66 23.54 11.5 6.675 3.632 8.671 discrepancy % 3 0.83 3 4.167 2.84 11.4 6.6 0.25 matlab 22.86 13.45 21.33 10.38 6 3.537 8.04 ansys 22.06 13 20.5 10.4 5.86 3 7.56 discrepancy % 3.5 3.346 3.89 0.2 2.33334 15.2 6 0.5 matlab 18.6676 11 18 8.5 4.86 2.8878 6.56 ansys 17.68 10.353 17 9.2 5.0845 2.37 6.24 discrepancy % 5.3 5.882 5.556 7.61 4.4 18 4.88 0.75 matlab 13.2 7.76 13.706 6.02 3.44 2.042 4.6415 ansys 11.4344 6.86 12.35 7.7455 4.1642 1.506 4.4672 discrepancy % 12 11.6 10 22.277 17.4 26.25 3.77 d references cccc ssss scsc cccf sssf sfsf cfcf 0 matlab 27 12.5 25.02 12 5.3 4.81 11 ansys 26.673 12.43 24.67 11.865 5.28 4.8 10.544 discrepancy % 1.2 0.56 1.4 1.125 0.377 0.208 4.1455 0.25 matlab 23.563 10.838 23.6 10.4 4.6 4.67 10.07 ansys 23.124 10.75 23.32 10.8 4.57 4.25 10 discrepancy % 1.863 0.812 1.186 3.7 0.65 9 0.7 0.5 matlab 19.55 8.86 22.2 8.55 3.76 3.65 8.48 ansys 18.773 8.757 21.88 9.6 3.7 3.63 9.056 discrepancy % 3.94 1.16 1.44 11 1.6 0.548 6.36 0.75 matlab 14.46 6.2876 20.7 6.1 2.667 3 6 ansys 12.653 6.15 20.34 8.2 2.61 2.876 7.97 discrepancy % 12.5 2.2 1.74 25.5 2.14 4.127 24.7 references a/b e1/e2 5 10 15 matlab 0.5 19.848 28.27 34.72 ansys 18.77 26.76 33 discrepancy % 5.43 5.34 5 matlab 1 5.88 7.4 8.654 ansys 6 7.5 8.74 discrepancy % 2 1.33334 1 matlab 1.5 3.814 4.54 5.17 ansys 3.84 4.553 5.1 discrepancy % 0.677 0.2855 1.354 mohammed b. hammed al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 2332 (2019) 30 fig. 2. mode shape for free vibration of (cfff) for (0/90/90/0) laminated square plate. 4. conclusion in the present work natural frequency of laminated plate with different angle schemes under ratios of thermal buckling load and general boundary conditions was developed using ritz method based on a permissible function for the first time. changing some design parameters such as thickness ratio, aspect ratio and orthotropic ratio are also studied, as expected fundamental frequency of the plate is affected by the ratio of initial thermal buckling load. the results present to this conclusions; the natural frequencies for laminates increase with the increase in aspect ratio and modules ratio e1/e2. the reduction of natural frequencies in angle ply laminates is much higher compared to cross ply laminate. the ssss plate is the most sensitive against simultaneous change in the system properties, and thermal expansion coefficients, while the cccc plate is the least sensitive (clamped edges conditions offer high stiffness). therefore, this investigation showed that this function can be used to find work natural frequency of laminated plate with different angle schemes under ratios of thermal buckling load and general boundary conditions. 5. references [1] achchhe lal and b. n. singh, “stochastic free vibration of laminated composite plates in thermal environments”, journal of thermoplastic composite materials, vol. 23, january 2010. [2] behrooz rahmani and amin ghorbani shenas. "robust vibration control of laminated rectangular composite plates in hygrothermal and thermal environment", composite structures, s0263-8223 (16)32874-4(2017). [3] chun-sheng chen, chih-wen chen, wei-ren chen and yi-chen chang. "thermally induced vibration and stability of laminated composite plates with temperature-dependent mohammed b. hammed al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 2332 (2019) 31 properties", meccanica, doi 10.1007/s11012013-9750-7(2013). [4] henry khov, wen l. li and ronald f. gibson, “an accurate solution method for the static and dynamic deflections of orthotropic plates with general boundary conditions”, composite structures, vol. 90, p. 474–481, 2009. [5] hossein amoushahi and farshad goodarzian. "dynamic and buckling analysis of composite laminated plates with and without strip delamination under hygrothermal effects using finite strip method", thin-walled structures, 131 (2018) 88–101. [6] j.n. reddy, “mechanics of laminated composite plates and shells: theory and analysis”, 2nd ed.; crc press llc, 2004. [7] ibtehal abbas sadiq, and kani hussein bawa. “vibration analysis of cross-ply plates under initial stress using refined theory”. alkhwarizmi engineering journal, vol. 14, no.4, december, (2018) p.p. 3444. [8] wael r. abdul-majeed. “restrained edges effect on the dynamics of thermoelastic plates under different end conditions.” alkhwarizmi engineering journal, vol. 8, no. 2, pp 1-11 (2012). [9] rath, m., and s. sahu. "vibration of woven fiber laminated composite plates in hygrothermal environment", journal of vibration and control, 2012. [10] moumita sit and chaitali ray. “a third order nonlinear model to study the dynamic behavior of composite laminated structures under the thermal effect with experimental verification.” composite structures, s02638223 (18)32606-0 (2019). [11] robert g. brown, “introductory physics i: elementary mechanics”, duke university physics department, 2007. [12] victor birman, “solid mechanics and its applications: plate structures”, springer science b.v. 2011. [13] w.l. li, “vibration analysis of rectangular plates with general elastic boundary supports”, journal of sound and vibration, vol. 273, p. 619–635,2004. [14] w.l. li, “free vibrations of beam with general boundary conditions”, journal of sound and vibration, vol.237, p.709–725, 2000. [15] li, xiangyang, kaiping yu, jingyong han, haiyang song and rui zhao. "buckling and vibro-acoustic response of the clamped composite laminated plate in thermal environment", international journal of mechanical sciences, s0020-7403 (16)30588-4(2016). [16] zainab abdul kareem abed. “buckling and pre stressed dynamics analysis of laminated composite plate with different boundary conditions”. al-khwarizmi engineering journal, vol. 15, no. 1, march, (2019) p.p. 4655. [17] w.l. li.., and m. daniels. "a fourier series method for the vibrations of elastically restrained plates arbitrarily loaded with springs and masses." journal of sound vibration vol. 252 (2002) pp: 768-781. )2019( 2332، صفحة 4لعدد ا، 15دجلة الخوارزمي الهندسية المجلممحمد بشير حميد 32 الحمل تحت العامة الحدود ذات المرنة الدعامات ذات المركبة للصفائح الحر االهتزاز تحليل األولي الحراري **د ابراهيم مجيدودا **محمد بشير حميد بغدادقسم الهندسة الميكانيكية / جامعة *،** wedad.ibrahim@coeg.uobaghdad.edu.iq**البريد االلكتروني: alabas@gmail.com88mohammed*البريد االلكتروني: خالصةال د معادلة الحركة اعتمتم اللوحات مغلفة رقيقة مركبة مع شرط الحدود المرنة العامة. نبعاجالحر في ظل نسبة درجة حرارة االيتم تطوير سلوك االهتزاز ة بينما تتكون وظائف الحل من دالة مثلثية ووظيفة مستمرة تضاف لضمان سالسة كافية لوظيفة اإلزاحة المتبقي (clpt) على نظرية األلواح الرقائقي الكالسيكية جنًبا إلى جنب مع تقنية ritzتم تطوير حل إجراء معمم باستخدام طريقة كما المعدلة ، fourierالمسماة على الحدود ، في هذا البحث ، تم استخدام سلسلة بقات ، ونسبة الحمل الحراري األولي تحليل تأثير العديد من معامالت التصميم مثل نسبة الُسمك ، ونسبة العرض إلى االرتفاع ، وزوايا الطمع التخيلية. النابض مقارنة النتائج الحالية مع تلك التي حصلنا عليها من قبل وتمتالظروف الحدودية المختلفة ، على الترددات الطبيعية للصفائح الرقائقي. فضال عنفي المستوى .اً جيد ااتفاق اعطتباحثين آخرين، و al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 112 (2014) comparison of fatigue life behavior between two different composite materials subjected to shot peening at different times ahmed n. al-khazraji* mahdi n. m. shareef** *,**department of machine and equipment engineering/ university of technology *e-mail: dr_ahmed53@yahoo.com **e-mail: mahdi.numaan@yahoo.com (received 24 march 2014; accepted 15 june 2014) abstract this paper investigated the fatigue life behavior of two composite materials subjected to different times of shot peening (2, 4 and 6 min).the first material prepared from unsaturated polyester with e-glass reinforcement by 33% volume fraction. while, the second one was prepared from unsaturated polyester with aluminum powder by2.5% volume fraction. the experimental results showed that the improvement in endurance limit was obtained (for the first material) at 2, 4 and 6 min shot peening times where the percentage of maximum improvement was 25% at shot peening time of 6 min. while, the endurance limit of the second material decreased at shot peening times of 2, 4 and 6 min where the percentage of maximum reduction was 29 % at shot peening time of 6 min. the verification of experimental results was done using ansys.14 workbench with a good agreement in behavior between the experimental and numerical. keywords: fatigue life, endurance limit, composite materials, shot peening time, polymer matrix composites. 1. introduction composite materials became an important materials due to wide use in practical application, such as airplane, spacecraft, automotive industries and other applications because it have low weight and high strength compared with the traditional metals and alloys. for this reason, many researchers studied how to improve the mechanical and fatigue properties of these materials. one of the methods used to create the compressive residual stresses was the shot peening to obtain surface improvement for the conventional metals and alloys. some researchers studied the effect of shot peening on the metallic matrix composite materials, but studying the effect of shot peening on polymeric matrix composite materials still very little and insufficient. so, this paper mainly focuses on this point.j. lu, et al. [1], studied the effect of shot peening on the residual stresses of a metal matrix composites (mmc) of aluminum alloys (2124 and 6061) as matrix and different silicon carbide (sic) in form of whiskers and particulates as fiber whose volume fraction range from 15% to 40%. the results showed that the residual stresses are compressive and isotropic which are beneficial for the fatigue life.s. tohriyama, et al. [2], investigated the influence of shot peening on fatigue life for two types of mmc of a6061 aluminum alloy reinforced with silicon carbide whisker (sicw) and a2024 aluminum alloy reinforced with silicon carbide particle (sicp) with a volume fraction of 20% produced by squeeze casting and powder metallurgy respectively. the peening time was (15 sec), shot diameter (105-250 µm), and coverage of (300%). the results showed that the shot peening improves the low cycle side fatigue strength of sicp/2024 but the high cycle side fatigue strength lowered. mailto:dr_ahmed53@yahoo.com mailto:mahdi.numaan@yahoo.com ahmed n. al-khazraji al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 112 (2014) 2 and for sicw/6061 composites, fatigue strength was not improved by shot peening. hill s. et al. [3], investigated the influence of shot peening on the fatigue performance of mmc under rotating bending loading conditions with a stress ratio of . the metal matrix composites are shown to respond favorably to shot peening for a given set of parameters. their results showed that fatigue strength of shot peened specimens were higher than for unpeened specimen at the same number of cycle to failure. weizhi luan et al. [4], investigated the influence of shot peening at time of (1 min) on the surface mechanical properties of the tib2/6351al composites. the matrix proof stress ( ) of the shot peened surface had been increased by 27% and the whole strength increment was about 21%. they concluded that the shot peening is an effective method to improve the surface strength of the tib2/6351al composite. 2. experimental work 2.1. materials selection in this paper, two types of polymer matrix composite materials were prepared, the first was constructed from unsaturated polyester (up) as a matrix and fiber glass (e-glass type in form of long (continuous)) as a reinforced material. the combination of the second one was unsaturated polyester reinforced by powder of aluminum. 2.2. preparation the specimens for testing the preparation of testing specimens were done as follow; 1. preparation the specimens by hand lay-up molding method according to standard of astm d 5687 [5]. 2. preparation of tensile test specimens according to standard of astm d 3039 [6]and astm d 638 [7] for fiber glass composites and aluminum powder composites, respectively as shown in figures (1-a) and (1-b). 3. preparation of fatigue test specimens according to machine specifications [8] as shown in figure (1-c). where the thickness of all tensile and fatigue specimens is 4 mm. the unsaturated polyester resin was mixed with the hardener (methyl ethyl keton peroxide, mekp) by a percentage of 2 %. for fiber glass composites, the composite plates was constructed by placing the fibers one above the other with the resin mixed well to spread them by using mould of (110 × 260 × 4) mm. this process was repeated with a constant volume fraction of 33%. for aluminum powder composites (with a particle size of (50 100 μm)), the powder was added slowly (with constant volume fraction of 2.5%) into the mixture and mixing it for more than 5 min to be homogeneous until a rise in the temperature of mixture will result as an indication to the beginning of the interaction process. the mixture was poured into the mould. the inside wall of the mould was covered by a layer of transparent fablon paper to avoid the adhesion of the resin with the mould. after that, a heavy load for pressing the mixture was put after pouring mixture in the mould to prevent any interaction between mixture and environment. after that, the sample stay in the mould for a period of 24 hour at room temperature and after that period, samples are extracted from the mould. to produce the test samples, the plate was cut into the appropriate dimensions using a tipped cutter which is very fine to ensure no vibration during cutting the samples and to avoid distortions that may occur during the process. (a) (b) (c) fig. 1. schematic diagram for [all dimensions in mm] with thickness of 4 mm for all specimens (a) tensile test specimens (astm d 3039) [6], (b)tensile test specimens (astm d 638) [7], and (c)fatigue test specimens[8]. 165 57 13 19 r 76 200 30 100 4 10 ahmed n. al-khazraji al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 112 (2014) 3 2.3. shot peening shot peening process was used in this paper, to study the variation in fatigue behavior for polymer matrix composite materials which are; (1) unsaturated polyester resin reinforced by 33 % e-glass fiber, and (2) unsaturated polyester resin reinforced by 2.5 % aluminum powder. the shot peening is accomplished by machine of sintokogio ltd, model stb-ob as shown in figure (2). in this machine, the motor rotates an impeller which bombard the shots towards the specimens at 1435 r.p.m motor rotational speed with one jet of shots at an average speed of 70 m/s. the material of the shooting balls is a low carbon steel with average diameter of 1.2 mm and coverage of 80-100 %. the peening machine consist of rotary cylinder with inside diameter of 590 mm and depth of 740 mm in which the specimens is placed. the time used for shot peening (spt) was three different times of (2, 4 and 6 min) on the prepared specimens. both tensile and fatigue specimens were subjected to shot peening at that times. 2.4. tensile test the type of used tensile test machine was microcomputer controlled electronic universal testing machine wdw-100e as shown in figure (3). tensile tests were done before and after shot peening and for all shot peening times. two specimens were tested for each case and taking the average value to satisfy an additional accuracy. 2.5. fatigue test the type of fatigue testing machine used in this work was hi-tech alternating bending fatigue (hsm20) with constant amplitude as shown in figure (4). the specimens were subjected to deflection perpendicular to the axis of specimens at one side of the specimens, and the other side was fixed, developing bending stresses as a cantilever beam which can be determined directly from the following equation; where; : is the maximum alternating stress (mpa), : the modulus of elasticity (gpa), : thickness of specimens (4 mm), : the deflection of free end side of the specimen measured by dial gauge (mm), : the effective length of specimen (60 mm). a series of tests are commenced by acting a specimen to the stress cycling and the number of cycles to failure is counted. this procedure is repeated on other specimens at progressively decreasing stress amplitudes. as a result, the surfaces of the specimens are under tension and compression stresses when the specimen fluctuated. all the tests done at constant stress amplitude loading with . the obtained data were plotted as stress s versus the logarithm of the number n of cycles to failure for each of the specimens. fig. 2. shot peening machine. fig. 3. tensile testing machine. ahmed n. al-khazraji al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 112 (2014) 4 fig. 4. fatigue testing machine. 3. numerical analysis the finite element method (fem) with aid of ansys.14 workbench software is used as a numerical tool to verify the shot peening effect on the fatigue polymer matrix composite materials. the solid-45 element with 8 nodes was used in this work. the meshing process has been done by choosing the volume and the number of elements in each body, as shown in figure (5-a). the total number of elements in each specimen was 3465 element with 17208 node. the load in the ansys workbench software will be at one side, and the other side was fixed support, as shown in figure (5-b). all the material properties for aluminum powder composites required in numerical analysis are imported from the experimental tests results, while for e-glass fiber composites (orthotropic) the material properties required in numerical analysis are imported depending on ref. [9].the resultant fatigue life was obtained for each specimen as shown in figure (5-c). the obtained fatigue lives were compared with the experimental results as shown in figure (12) and figure (13). (a) (b) (c) fig. 5. the model specimen (a) mesh (b) applying load (c) fatigue life. 4. results and discussion 4.1. tensile test results from the tensile test, the ultimate tensile strength and modulus of elasticity for each types of composite materials were obtained. the tensile test properties were changed due to the submission the polymer matrix composites to the shot peening process. the mechanical properties of the studied composite materials were orthotropic for unidirectional fiber glass reinforced polyester and isotropic for aluminum ahmed n. al-khazraji al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 112 (2014) 5 powder reinforced polyester. figure (6-a) shows the stress-strain diagram for polyester resin reinforced by e-glass fiber with volume fraction of 33% and figure (6-b) shows the stress-strain diagram for polyester resin reinforced by aluminum powder with volume fraction of 2.5 %. this figure clarify the effect of treatment by shot peening process on the mechanical properties, where a direct comparison was performed between the shot peened and the unpeened specimens. the tensile test results (ultimate tensile strength and modulus of elasticity) are listed in table 1. for fiber glass composites (as shown in figure (7) and figure (8)), the mechanical properties improved gradually where the maximum improvement was about 5 % at (spt = 6 min) with respect to the unpeened specimens (spt = 0 min).figure (9) reveals a reduction in mechanical properties for 2.5% aluminum powder composites where the maximum reduction did not reaches 23% at (spt = 6 min) with respect to the unpeened specimens (spt = 0min). (a) (b) fig. 6. stress-strain diagram for polyester and (a) 33 % volume fraction fiber glass composites, and (b) 2.5 % volume fraction aluminum powder composites. table 1, mechanical properties before and after shot peening. spt mechanical properties fiber glass composites aluminum powder composites longitudinal transversal 0 min σ ult (mpa) 383 10 34.35 e (gpa) 22.17 10.943 6.249 2 min σ ult (mpa) 390 10.2 31.28 e (gpa) 22.575 11.16 5.687 4 min σ ult (mpa) 394 10.32 28.66 e (gpa) 22.8 11.293 5.211 6 min σ ult (mpa) 401 10.38 26.5 e (gpa) 23.212 11.36 4.82 0 100 200 300 400 500 0 0.5 1 1.5 2 σ (mpa) strain % 0 min 2 min 4 min 0 10 20 30 40 50 0 0.1 0.2 0.3 0.4 0.5 0.6 σ (mpa) strain % 0 min 2 min 4 min ahmed n. al-khazraji al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 112 (2014) 6 (a) (b) fig. 7. variation of mechanical properties at different spt forlongitudinal fiber glass composites (a) ultimate tensile strength (b) young's modulus. (a) (b) fig. 8. variation of mechanical properties at different spt transverses fiber glass composites (a) ultimate tensile strength (b) young's modulus. (a) (b) fig. 9. variation of mechanical properties at different spt for aluminum powder composites (a) ultimate tensile strength (b) young's modulus. 22 23 24 0 2 4 6 e (gpa) shot peening time (min) 380 400 420 0 2 4 6 σ (mpa) shot peening time (min) 9 10 11 0 2 4 6 σ (mpa) shot peening time (min) 10 11 12 0 2 4 6 e (gpa) shot peening time (min) 0 10 20 30 40 0 2 4 6 σ (mpa) shot peening time (min) 0 2 4 6 8 0 2 4 6 e (gpa) shot peening time (min) ahmed n. al-khazraji al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 112 (2014) 7 4.2. fatigue test results the fatigue behavior before and after shot peening is illustrated as s-n curves, as shown in figure (10-a)for fiber glass composites and figure(10-b) for aluminum powder composites. these curves give an indication about the variations in fatigue life. from these data, the fatigue life estimation equations were determined using the power law regression; where; : is the fatigue stress amplitude (mpa), n : is the number of cycles to failure(mpa), aandb : are constants depend on material. the value of endurance limit is not clearly obvious on the s-n curve; therefore, the endurance limit can be calculated by using the fatigue life estimation equation at 106 cycles. the fatigue life estimation equations are listed in table 2 and the endurance limitsare listed in table 3. for the fiber glass composites (polyester with e-glass of 33% volume fraction), it can be seen from figure(10-a) that the shot peening treatment showed an increasing in the fatigue life in all cases as compared to the unpeeneds-n curve across the whole range of stress amplitudes, as well as an increasing in the endurance limit. the best improvement in fatigue life (endurance limit) was at 6 min shot peening time with a percentage of25% as compared with the unpeened case. for aluminum powder composites(polyester with aluminum of 2.5 % volume fraction),it can be seen from figure (10-b) thatthe shot peening treatment showed a decreasing in endurance limit in all cases as compared with the unpeened s-n curve across the whole range of stress amplitudes, as well as a decreasing in the endurance limit. the maximum reduction in fatigue life (endurance limit) was at 6 min shot peening time with a percentage of29 % as compared with the unpeened case. figure (11-a) shows an increasing in the endurance limit for the fiber glass composites as the shot peening time increasing, where the endurance limit increased from 184.12mpaat (spt = 0 min) until reaches 230.245mpa at (spt = 6 min). besides that, figure (11-b) can give an indication about the reduction in endurance limitfor the aluminum powder composites as the shot peening time increasing, where the endurance limit decreased from 12.7mpaat (spt = 0 min) until reaches 9.03mpa at (spt = 6 min). the increment in mechanical and fatigue properties offiber glass composites with the shot peening due to the generating compressive residual stresses at the surface layer of the specimen. the reduction in properties of aluminum powder composites due to formation of cracks at the surface of the specimens and generating tensile residual stresses at the surface layer. it is observed that the fiber glass composites have fatigue strength more than ten times for aluminum powder composites. generally, the properties of fiber glass composites have a high value as compared with aluminum powder composites. fibers are the main load carrying material in composites, and as the number of load carrying elements increases in a material, its strength increases. fiber glass composites give higher results due to the fibers that can withstand more loads when compared to the powder. the numerical behavior of fatigue life for all cases can be expressed in figure(12) and figure (13). from these figures, the s-n curves equations can be concluded as in eq. (2), which are also listed in table 2. the numerical endurance limit can be obtained from the s-n curve equation at 10 6 cycle and given in table 3. in this table, the percentage error of endurance limit between the experimental work and numerical analysis is also listed, which is also calculated by the following equation; …(3) it is clear from the comparison figures that the experimental s-n curves are agreed with the numerical s-n curves. ahmed n. al-khazraji al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 112 (2014) 8 (a) (b) fig. 10. semi-log s-n curves for polyester and (a) 33 % volume fraction fiber glass composites, and (b) 2.5 % volume fraction aluminum composites. (a) (b) fig. 11. relationship between endurance limit and spt for (a) 33 % volume fraction fiber glass composites, and (b) 2.5 % volume fraction aluminum composites. 100 150 200 250 300 350 1e+03 1e+04 1e+05 1e+06 σa (mpa) n (cycle) unpeened 2 min 4 min 0 5 10 15 20 25 30 35 1e+03 1e+04 1e+05 1e+06 σa (mpa) n (cycle) unpeene d 150 170 190 210 230 250 0 2 4 6 en d u ra n ce l im it ( m p a ) shot peening time (min) 5 7 9 11 13 15 0 2 4 6 en d u ra n ce l im it ( m p a ) shot peening time (min) ahmed n. al-khazraji al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 112 (2014) 9 (a) (b) (c) (d) fig. 12. semi-log s-n curves comparison between experimental and numerical data for fiber glass composites at spt of (a) 0 min (b) 2 min (c) 4 min (d) 6 min. table 2, experimental and numerical equations of s-n curves for all cases. numerical s-n equation experimental s-n equation spt (min) material type σ 78 4 n -0.133 σ 9 676 n -0.143 0 polyester + 2.5 % al σ 88.777n -0.1485 σ 84.874n -0.1418 2 σ 89.972 n -0.1593 σ 93.6282n -0.1596 4 σ 92.32n -0.1724 σ 9 n -0.1681 6 σ = 939.12 n -0.121 σ = 972.972 n -0.1205 0 polyester + 33 % fiber glass σ = 812.123 n -0.1021 σ = 808.112n -0.0986 2 σ = 1026.445 n -0.1147 σ = 1012.015n -0.1102 4 σ = 1099.956 n -0.1158 σ = 1146.543 n -0.1162 6 100 150 200 250 300 350 1e+04 1e+05 1e+06 s (mpa) n (cycle) exp num 100 150 200 250 300 350 1e+04 1e+05 1e+06 s (mpa) n (cycle) exp num 100 150 200 250 300 350 1e+04 1e+05 1e+06 s (mpa) n (cycle) exp num 100 150 200 250 300 350 1e+04 1e+05 1e+06 s (mpa) n (cycle) exp num ahmed n. al-khazraji al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 112 (2014) 10 (a) (b) (c) (d) fig. 13. semi-log s-n curves comparison between experimental and numerical data for aluminum powder composites at spt of (a) 0 min (b) 2 min (c) 4 min (d) 6 min. table 3, experimental and numerical endurance limit for all cases. error % by eq.(3) numerical endurance limit (mpa) experimental endurance limit (mpa) spt (min) material type 1.81 12.483 12.7133 0 polyester + 2.5 % al 4.65 11.41 11.9667 2 3.5 9.9611 10.323 4 5.55 8.529 9.03 6 4.14 176.5 184.12 0 polyester + 33 % fiber glass 4.25 198.16 206.953 2 4.68 210.444 220.794 4 3.53 222.11 230.245 6 0 5 10 15 20 25 1e+03 1e+04 1e+05 1e+06 s (mpa) n (cycle) exp 0 5 10 15 20 25 1e+03 1e+04 1e+05 1e+06 s (mpa) n (cycle) exp num 0 5 10 15 20 25 1e+03 1e+04 1e+05 1e+06 s (mpa) n (cycle) exp num 0 5 10 15 20 1e+03 1e+04 1e+05 1e+06 s (mpa) n (cycle) exp num ahmed n. al-khazraji al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 112 (2014) 11 5. conclusions the main conclusions drawn from this paper are; 1. increasing the shot peening time increases the endurance limit of fiber glass composites with maximum increasing of about 25 % at (spt = 6 min) to a value of about 230.245mpa compared with 184.12mpa for the unpeened case (spt = 0 min). 2. increasing the shot peening time decreases the endurance limit of aluminum powder composites with maximum decreasing of about 29 % at (spt = 6 min) to a value of about9.03mpa compared with 12.7133mpa for the unpeened case (spt = 0 min). 3. the mechanical properties of 33% e-glass fiber composites increased with increasing shot peening time by a percentage of about 5 %and the mechanical properties of 2.5 % aluminum powder composites decreased with increasing shot peening time by a percentage of about 10 %. 4. the e-glass fiber composites give material with orthotropic properties.while, the aluminum powder composites give material with isotropic properties. 5. the properties of powder composites depend mainly on the resin material properties which can be affected by the additive powder as compared with long fiber reinforcements. 6. the numerical results (by finite element method with aid of ansys.14 workbench) showed a good agreement with the experimental results where the maximum error does not exceed 5.55 % for endurance limit for all cases. 6. references [1] j. lu, b. miège and j. f. flavenot, "study on the effect of shot peening on the residual stress in al-sic composite" , france, pp. 169-178,1989. [2] s. tohriyama, m. kumano and s. hisamatsu, "influence of peening on fatigue life of sic reinforced aluminum " material development depatment, isuzu motors limited, japan, pp. 307-316, 1990. [3] hill s., gregson p. j. and o'hara p., "effect of shot peening on fatigue performance of advanced aluminum alloys and aluminum based metal matrix composites" engineering materials, university of southampton, uk, metal improvement company, pp. 371-376 1992. [4] weizhi luan, chuanhai jiang, vincent ji and haowei wang, "effect of shot peening on surface mechanical properties of tib2al composite" journal material science 44, pp. 2454-2458 2009. [5] american society for testing and materials (astm) d 5687/d 5687 m-95 "standard guide for preparation of flat composite panels with processing guidelines for specimen preparation" annual book of astm standards, 1995. [6] american society for testing and materials (astm) d 3039/d 3039 m " standard test method for tensile properties of polymer matrix composite materials" annual book of astm standards, 2000. [7] american society for testing and materials (astm) d 638 " standard test method for tensile properties of plastics" annual book of astm standards, 2001. [8] n. p. roberts and nigel r. hart, "alternating bending fatigue machine (hsm20), instruction manual" , hi-tech ltd. uk., 2001. [9] muhannad z. khelifa andhayder m. alshukri "fatigue study of e-glass fiber reinforcedpolyester compositeunder fully reversed loading and spectrum loading" eng.& technology journal,vol. 26, no.10, 2008. (2014) 112، صفحة 3، العدد10دجلة الخوارزمي الهندسية المجلاحمد نايف ابراهيم م 12 مختلفتين تحت تأثير أزمنة مختلفة للسفع بالكراتمقارنة سلوك عمر الكالل لمادتين مركبتين **مهدي نعمان مسلم *أحمد نايف ابراهيم الخزرجي الجامعة التكنولوجية/ قسم هندسة المكائن والمعدات **،* dr_ahmed53@yahoo.com *االلكتروني البريد : mahdi.numaan@yahoo.com كترونيلالا البريد : ** الخالصة المادة المركبة االولى (. دقائق 6و 4و 2)ألزمنة مختلفة من السفع بالكرات ينتم في هذا البحث دراسة تأثر سلوك عمر الكالل لمادتين مركبتين خاضعت بينما كانت المادة االخرى محضرة من البولي أستر غير %. 33ضرت من مادة البولي أستر غير المشبع مع مدعمات من الليف الزجاجي بكسر حجمي ح و 2) راتبالك سفعأظهرت النتائج العملية بأن التحسن في حد الكالل قد حصل للمادة االولى عند أزمنة %. 2.2المشبع مع مسحوق االلمنيوم بكسر حجمي بينما قّل حد التحمل للمادة الثانية عند أزمنة السفع بالكرات . ائقدق 6عند زمن سفع بالكرات قدره % 22حيث كانت أقصى نسبة مئوية للتحسن (دقائق 6و 4 ستخدام برنامج ائج العملية بابرهنة النت وتمت. قائقد 6عند زمن سفع بالكرات قدره % 22حيث كان أقصى نقصان بنسبة مئوية (دقائق 6 و 4و 2) (ansys.14 workbench) يل النظريلوبمقبولية جيدة بين العملي والتح. mailto:mahdi.numaan@yahoo.com*البريد mailto:mahdi.numaan@yahoo.com*البريد mailto:dr_ahmed53@yahoo.comالبريد mailto:dr_ahmed53@yahoo.comالبريد _31-52_ yasin k. salman 31 free convective heat transfer with different sections lengths placed at the exit of a vertical circular tube subjected to a constant heat flux yasin k. salman hussein a. mohammed baghdad university baghdad university, college of engineering college of engineering nuclear eng. dept., baghdadal-jaderyia, iraq baghdadal-jaderyia, iraq (received 24 january 2006; accepted 11 june 2007) abstract: a free convective heat transfer from the inside surface of a uniformly heated vertical circular tube has been experimentally investigated under a constant wall heat flux boundary condition for laminar air flow in the ranges of ral from 6.9×108 to 5× 109. the effect of the different sections (restrictions) lengths placed at the exit of the heated tube on the surface temperature distribution, the local and average heat transfer coefficients were examined. the experimental apparatus consists of aluminum circular tube with 900 mm length and 30 mm inside diameter (l/d=30). the exit sections (restrictions) were included circular tubes having the same inside diameter as the heated tube but with different lengths of 600 mm (l/d=20), 900 mm (l/d=30), 1200 mm (l/d=40), 1500 mm (l/d=50), and 1800 mm (l/d=60). it was found that the surface temperature along the tube axial distance would be higher for restriction with length of 1800 mm (l/d=60) and it would be smaller for the restriction with length of 1200 mm (l/d=40). the results show that the local nux and average nusselt number nu were higher values for the restriction with length of 1200 mm (l/d=40) and smaller values for the restriction with length of 1800 mm (l/d=60). the results were correlated with empirical equations and presented as log lnu against log lra for each case investigated and a general empirical equation was proposed for all cases. keywords: experimental study; free convective; different sections length; vertical circular tube; constant heat flux. introduction free convective heat transfer has always been of particular interest among heat transfer problems. in free convection process, fluid motion is caused by density variations resulting from temperature difference between the fluid and the contacting surface. many experimental studies have been performed during the last contacting surface. many experimental studies have been performed during the last alkhwarizmi engineering journal vol.3 , no3. , pp 31-52(2007) alkhwarizmi engineering journal yasin k. salman /al-khwarizmi engineering journal, vol.3, no.3, pp 3152 (2007) 32 three decades and interesting results have been presented. the free convection from cylinders or tubes of circular shapes have been receiving growing interest in the last few decades because of its employment in many practical fields in the area of energy conservation, design of solar collectors, heat exchangers, nuclear engineering, cooling of electrical and electronic equipments and many others, kakac (1987). heat transfer studies of free convection from circular tubes are necessary for better thermal design of industrial applications. although some theoretical and experimental investigations have been published it is to be noted that they are far from sufficient. experiments using different fluids and different values of length to diameter ratio in both the isothermal surface and the constant wall heat flux conditions are still needed to enable a complete investigation of the problem. therefore, the present work was carried out in an attempt to fill a part of the existing gap and provides experimental data by experimentally investigating free convection heat transfer from the heated inside surface of a vertical tube to air at constant heat flux. the available work on free convection from the inside surfaces of vertical tubes open at both ends with restriction at exit is limited. however, most of the available investigations are theoretical and deal with the vertical tube in special cases only. to the authors knowledge limited prior work is available on this case, which studied in the present work. oliver (1962) investigated experimentally laminar flow of relatively non-viscous newtonian liquids through a vertical jacketed tube. it was shown that better agreement was obtained when the ratio d/l is omitted from the group and further improvement results from the incorporation of the ratio l/d, all the data being adequately represented by an empirical equation. this equation becomes inaccurate when gzm < π nuam and it should be mentioned that the power of l/d is only provisional ( ) 0.14 1/ 34 0.7w m m m mnu 1.75 gz 5.6 10 (gr pr l/ d) β µ µ −  = + ×     (1) martin (1965) made predictions of the lower limiting conditions of free convection in the vertical open thermosyphon of circular cross-section with uniform wall temperature. the overall heattransfer rate was independent of tube length but proportional to radius, unless the lengthradius ratio is below about 1·8, in which case it depends also on temperature conditions at the closed end. the corresponding rayleigh number was estimated for non-metallic fluids and for a liquid metal. but, dyer (1975) presented a theoretical and experimental study of laminar air flow natural convective in heated vertical ducts. the temperature and velocity fields and the relationship between nu and ra numbers were obtained by solving the governing equations by a stepby-step numerical technique. the influence of pr number was discussed. experiments were conducted for ra number between 1 to 13000. three ducts were used of different sizes and these ducts were 19.1, 25.4, and 46.7 mm in internal diameter and were all 1220 mm in long. comparison between experimental and theoretical studies was carried out and showed good agreement. kokugan and kinoshita (1975) performed experimental work in a heated vertical open tube consisting of heated section at constant wall temperature. correlations between gr and re numbers were derived by setting up a mechanical energy balance in the tube. the following equation was proposed: 2 o o h o ogr 6.3 re 3.2( l l ) /( d.re )= + + . (2) where: lh =heated length; lo= entrance length and subscript (o) denoted to at room temperature. the results were compared with available numerical results. hess and miller (1979) carried out experiments using a laser doppler velocimeter (ldv) to measure the yasin k. salman /al-khwarizmi engineering journal, vol.3, no.3, pp 3152 (2007) 33 axial velocity of a fluid contained in a cylinder subject to constant wall heat flux on the side walls. the modified rayleigh numbers ranged between 4.5×109 to 6.4×1010, which corresponds to the upper limit of the laminar regime. the variations of axial velocity with radius for different heights in the bottom and top parts of the cylinder and inside the thermal boundary layer region and with radius for different time were presented. the variation of radial position of maximum velocity and radial position of zero velocity with rayleigh number were also depicted. excellent agreement was obtained with the available numerical solution. shigeo and adrian (1980) studied experimentally natural convection in a vertical pipe with different end temperature with (l/d=9). the rayleigh number was in the range 108<ra<1010. it was concluded that the natural convection mechanism departs considerably from the pattern known in the limit ra → 0. specifically, the end-to-end heat transfer was affected via two thin vertical jets, the upper (warm) jet proceeding along the top of the cylinder toward the cold end and the lower (cold) jet advancing along the bottom in the opposite direction. the nusselt number for end-to-end heat transfer was shown to vary weakly with the rayleigh number. shenoy (1984) presented a theoretical analysis of the effect of buoyancy on the heat transfer to non-newtonian power-law fluids for upward flow in vertical pipes under turbulent conditions. the equation for quantitative evaluation of the natural convection effect on the forced convection has been suggested to be applicable for upward as well as downward flow of the power-law fluids by a change in the sign of the controlling term. chang et al. (1986) investigated theoretically the role of latent heat transfer in connection with the vaporization of a thin liquid film inside a vertical tube. the results were specifically presented for an air-water system under various conditions. the effects of tube length and system temperatures on the momentum, heat and mass transfer in the flow were examined. the important role that the liquid film plays under the situations of buoyancy-aiding and opposing flows was clearly demonstrated. al-arabi et al. (1991) investigated experimentally natural convection heat transfer from the inside surfaces of vertical tube to air in the ranges of grl.pr from 1.44×107 to 8.85×108 and (l/d) ranged from 10 to 31.4. the results obtained were correlated by dimensionless groups as follows: 0.25 ml ml ms i 1.11nu ( gr pr) [ 1 0.05 ( t t )] = + − .. (3) it was inferred that the effect of (l/d) on numl was insignificant and the entrance length was practically constant. the results were compared with the theoretical results of dyer (1975) and showed a good agreement. abd-el-malek and nagwa (1991) developed an analysis of transformation group method to study fluid flow and heat transfer characteristics for steady laminar free convection on vertical circular cylinder. the form of the surface temperature variation was derived as a linear variation with the vertical coordinate. the system of ordinary differential equations was solved numerically using a fourth-order rungekutta scheme and the gradient method. the effects of the cylinder heating mode and the prandtl number on the velocity and temperature profiles were presented. it was found that the maximum value of the vertical component of the velocity decreases with the increase of both the prandtl number and the surface temperature. fukusako and takahashi (1991) investigated the influence of density inversions and free convection heat transfer of air-water layers in a vertical tube with uniformly decreased wall yasin k. salman /al-khwarizmi engineering journal, vol.3, no.3, pp 3152 (2007) 34 temperature. holographic interferometry was adopted to determine the time-dependent temperature distribution in the tube. the temperature and the flow patterns were markedly influenced by the cooling rate of the tube. the heat transfer characteristics along the tube wall were also determined. yan and lin (1991) performed combined theoretical and experimental study to investigate natural convection in vertical pipe flows at high rayleigh number. the wall conduction effects and thermal property variations of the fluid and pipe wall were also considered. the predicted and measured distributions of wall temperature and nusselt number were in good agreement. the empirical correlations for the induced flow rate and average nusselt number were proposed. vinokurov et al. (1993) carried out an experimental investigation of unsteady-state free convection in a vertical cylindrical channel for the case of nonuniform distribution of heat flux along a channel at a constant wall temperature. the averaged temperature field in a gas was investigated on a mach-zender interferometer. hydrodynamic structures were investigated by the smoke visualization technique. the longitudinal and lateral rayleigh numbers were varied from 0 to 4×109 and from 0.8×104 to1.2×105, respectively. the air, carbon dioxide and helium were used in this study as working fluids. yissu (1995) examined numerically and experimentally laminar natural convection in vertical tubes with one end open to a large reservoir, to predict the flow behavior and the heat transfer rates. in the numerical study, a semi-implicit, timemarching, finite-volume solution procedure was adopted to solve the governing equations. the experimental work involved the use of a mach-zehnder interferometer to examine the temperature field for a modified rectangular open thermosyphon through the interpretation of fringe patterns. the nusselt numbers were determined from the interferometer results and compared with numerical results. it was found that the heat transfer rates through the tube wall to be strong functions of the tube radius, and approached an asymptotic limit as the tube radius was increased. kuan-tzong lee (2000) presented a closed form solution for the fully developed laminar natural convection heat and mass transfer in a vertical partially heated circular duct. thermal boundary conditions of uniform wall temperature/uniform wall concentration (uwt/uwc) and uniform heat flux /uniform mass flux (uhf/umf) were considered. wojciech (2000) presented experimental and numerical studies of natural convection in a vertical tube placed between two isothermal walls of different temperature. two experimental set-ups were built for visualizing the flow and to measure the temperature around the tube and walls confined in the close cavity. an fem computer code was applied for analyzing the influence of various parameters on the flow structure and heat transfer. the measurements were taken for rayleigh number: for slot ras=2×107–1×109; for tube rar=6×102 9×102. it was found that the intensity decreased and increased unexpectedly and the explanation can be given after visualization. it was observed that the hot air near the heated wall aspirated the layers of hot air from the vertical tube. the uplift pressure and the tendency of the system were reached the balance because the air layers of the similar temperature and density were merged. however, this effect (similar to the movement of the hot air in a chimney) also found to be dependent on the intensity of the heat transfer. he et al. (2004) investigated numerically natural convection heat transfer and fluid flow in a vertical cylindrical envelope with constant but yasin k. salman /al-khwarizmi engineering journal, vol.3, no.3, pp 3152 (2007) 35 different temperatures of the two end surfaces and an adiabatic lateral wall. the simulation was conducted for two end wall temperature differences: δtw=10 and 220 k. for the cases of δtw=10 k, it was found that the variation patterns of nul versus ral within the range of l/d=3-10 were in good consistency with the available experimental and theoretical results. for the case of large temperature difference (δtw=220 k) the natural convection in the enclosure was quite strong in that the convective heat transfer rate was about two-orders larger than that of pure heat conduction which occurs when the cold end is placed down. the numerical simulation also revealed that the ratio of the axial length, l, to the diameter, d, has effect on the average heat transfer rate of the envelope under the same other conditions. it was concluded that within the range of l/d=1–9, the increase in l/d leads to the decrease in heat transfer rate. popiel and wojtkowiak (2004) presented an experimental investigation on average natural convection heat transfer from the isothermal vertical surfaces of a short and slender square cylinder to air obtained with a lumped capacitance method. a validation of experiments was performed with the short circular cylinder and showed very good agreement with the formula of (mcadams, 1974) which is recommended for a flat isothermal plate. moawed (2005) studied experimentally natural convection from uniformly heated helicoidal pipes oriented vertically and horizontally. four helicoidal pipes of different parameters were presented. the effects of pitch to pipe diameter ratio, coil diameter to pipe diameter ratio and length to pipe diameter ratio on the average heat transfer coefficient were found. the experiments covered a range of rayleigh number based on tube diameter from 1.5×103 to 1.1×105. the results showed that the overall average nusselt number, num, increases with the increase in pitch to pipe diameter ratio, coil diameter to pipe diameter ratio and length to pipe diameter ratio. it is clear from the above literature review that there are limited studies which deal with the effect of the restrictions placed at the exit of a vertical circular tube on the heat transfer from the inside surface with different sections (restrictions) lengths. thus, the purpose of the present study was to provide experimental data on free convective heat transfer from open ended vertical circular tube with a constant heat flux and with different sections (restriction) lengths and to propose a general empirical equation for this problem. experimental apparatus and procedure the experimental apparatus used in the present work consists of a circular tube (test section) mounted on a specially constructed wooden frame. the frame has the capability of rotating the test section around its horizontal axis and changing its inclination angle. the heated section proceeded with circular sections (restrictions) with different lengths, as well as, different grashof number as shown schematically in fig.1a, to investigate the free convection heat transfer in a vertical circular tube opens at both ends. the heated tube (3) is made from aluminum tube of 900 mm length, 30 mm inside diameter (l/d=30) with a thickness of 5 mm provided with changeable restriction tubes (1) with five different lengths, particulars of which are: cylindrical tubes with lengths of 600 mm (l/drest.=20), 900 mm (l/drest.=30), 1200 mm (l/drest.=40), 1500 mm (l/drest.=50), and 1800 mm (l/drest.=60) placed at the exit of the heated section as shown in fig. 1a. the air enters from the atmosphere through the circular (restriction) tube into the heated section and then the heated air was exhausted to the atmosphere. the teflon connection pieces: yasin k. salman /al-khwarizmi engineering journal, vol.3, no.3, pp 3152 (2007) 36 represents a part of the test section inlet (4) and another teflon piece represents the test section exit (5). the restriction tubes were connected with the heated tube by teflon connection piece (4) bored with the same inside diameter of the heated tube and the restriction tube as shown in fig. 1a. the teflon was chosen because its low thermal conductivity in order to reduce the test section ends losses. the outer surface of the tube was covered with an electric insulating tape on which nickel-chrome wire (3) of 0.4 mm is electrically isolated by ceramic beads, uniformly wounded along the tube as a coil in order to give uniform heat flux as shown in fig. 1b. the outside of the test section was then thermally insulated by an asbestos layer (4) with 20 mm thickness, and with 18 mm thickness of fiberglass layer (5). two pairs of thermocouples (6) were installed in the asbestos layer between the heater and the insulation at three stations along the heated section as shown in fig. 1b in order to perform the heat loss calculation through the test section lagging. the heat losses from the ends of the test section could be evaluated by inserting two thermocouples in each teflon piece. by knowing the distance between these thermocouples and the thermal conductivity of the teflon, the end losses could be calculated. the thermocouples of each pair were fixed on the same radial line. the input power to the heater was adjusted so that at steady state, the readings of the thermocouples (6) of each pair become practically the same. thirty five alumelchromel (type k) thermocouples (2) of 0.2 mm diameter were soldered in slots milled in the axial direction to measure the surface temperature of the test tube as shown in fig. 1b. the measuring junctions were permanently secured in the holes by sufficient amount of high temperature application defcon adhesive (4) as shown in fig. 1c. all thermocouples were calibrated using the melting points of ice made from distilled water as reference point and the boiling points of several pure chemical substances. the calibration of thermocouples showed that they were accurate to within ± 0.2 °c. the inlet bulk air temperature was measured by one thermocouple placed at the beginning of the restriction tube, while the outlet bulk air temperature was measured by two thermocouples located at the test section exit 'mixing chamber' (7) as shown in fig. 1a. the local bulk air temperature was calculated by fitting straight lineinterpolation between the measured inlet and outlet bulk air temperatures since the wall heat flux boundary condition is applied. the choice of the linear distribution of the bulk air temperature is attributed to the following reasons: for constant wall heat flux (q) boundary condition, the bulk temperature gradient is calculated from: b s b d t q.p p h(t t ) dx mcp m cp = = − & & …….. (4) where p is the surface perimeter = π d for circular tube. from the above equation the axial variation of tb may be determined. if ts > tb heat is transferred to the fluid and tb increases with x, if ts < tb the opposite is true. for constant heat flux (q) it follows the right hand side of eq. (4) is a constant independent of the distance (x), hence, bd t q.p dx mcp = & ……………….………… (5) by integrating from x=0, it follows that b b,i q.pt ( x) t x mcp = + & ……………….…. (6) accordingly, the bulk temperature varies linearly with the distance (x) along the tube. moreover, from s bq h (t t )= − …………………………..(7) yasin k. salman /al-khwarizmi engineering journal, vol.3, no.3, pp 3152 (2007) 37 the temperature difference (ts-tb) varies with the distance (x). the difference is initially small (due to the large value of the heat transfer coefficient at the tube entrance) but increases with increasing the distance (x) due to the decrease in heat transfer coefficient that occurs as the thermal boundary layer develops as has been reported by incropera and dewitt (2003). the readings of all thermocouples were taken by a precalibarted digital temperature recorder capable of reading 0.01 °c via a multi-switch. the apparatus was mounted in a closed room with plastic transparent shields (2) as shown in fig. 1a to prevent currents of air, and the measuring instruments were mounted outside of this room. the input electric power to the heater was controlled and changed by the ac variac at each experiment and measured by a digital wattmeter with a resolution of 0.01 w. the steady state condition for each run was achieved after 4 approximately hours. the steady state was considered to be achieved when the temperature reading of each thermocouple did not change by more than 0.5 °c within 20 minutes. when the steady state condition was established, the readings of all thermocouples, the input power and the inlet and outlet bulk temperatures were recorded. experimental uncertainty generally the accuracy of experimental results depends upon the accuracy of the individual measuring instruments and the manufacturing accuracy of the circular tube. the accuracy of an instrument is also limited by its minimum division (its sensitivity). in the present work, the uncertainties in heat transfer coefficient (nusselt number) and rayleigh number were estimated following the differential approximation method reported by holman (2001). for a typical experiment, the total uncertainty in measuring the heater input power, temperature difference (ts-ta), the heat transfer rate and the circular tube surface area were 0.38%, 0.48%, 2.6, and 1.3% respectively. these were combined to give a maximum error of 2.43% in heat transfer coefficient (nusselt number) and maximum error of 2.36% in rayleigh number. data reduction in the present work the following steps were used to analyze the natural convection heat transfer process for air flow in a vertical circular tube when its surface was subjected to a constant wall heat flux boundary condition. the total input power supplied to the heated tube can be calculated: 2 tq i r = × ……………………………..(8) the convection heat transferred from the heated tube surface: conv. t cond .q q q= ……………………. (9) where: qcond. is the total conduction heat losses (lagging and ends losses) and its calculated from ( )cond . thq t / r∆= where: fiberglass layer asbestos layert t t∆ = − and rth is the thermal resistance of the insulations o i th insulations ln( r / r )r 2 k lπ = where: ro is the outer radius of the heated tube and ri is the inner radius of the heated tube. it was found that the conduction heat losses from the heated section are approximately about 4% of the total input power. the convection heat flux can be represented by: yasin k. salman /al-khwarizmi engineering journal, vol.3, no.3, pp 3152 (2007) 38 conv. conv. s q q a = ………………….. (10) where: as= π × d× l the convection heat flux, which is used to calculate the local and average heat transfer coefficient as follows: conv. x sx bx qh t t = − ……………..……. (11) where: tsx is the local surface temperature, and tbx is the local bulk air temperature. all the air properties were evaluated at the mean film temperature as reported in cengel (2004). sx bx fx t tt 2 + = ……………… .. (12) where: tfx is the local mean film air temperature. the local nusselt number (nul) can be determined as: x l h .l nu k = …………………….. (13) the average values of nusselt number l( nu )can be calculated based on the average heat transfer coefficient as follows: x l l x x 0 1h h dx l = ∫ = = …………………. ….. (14) l l h .lnu k = ……………………… (15) the average values of the surface temperature, bulk air temperature and mean film temperature can be evaluated as follows: x l s sx x 0 1t t dx l = ∫ = = ………………….. …. (16) x l a bx x 0 1t t dx l = ∫ = = …….. ……… (17) s a f t tt 2 + = ………………………..…(18) . the grashof and the rayleigh numbers can be determined as follows: 3 s a l 2 g l (t t )gr β ν − = ……….…….(19) l lra gr pr= × …………………………. (20) where: f1 /( 273 t )β = + , all the air physical properties ( , ,ρ µ ν and κ ) were evaluated at the average mean film temperature ( ft ), but it was observed in most of the previous work investigations that the physical properties were taken at the mean film temperature which is based on ambient temperature at tube entrance and given by [tmf =(tms+ti) /2] . results and discussion free convection of air was experimentally studied in a vertical circular tube of different sections (restrictions) lengths placed at the exit of the heated tube. the heated tube was subjected to constant wall heat flux boundary conditions. the effects of the restriction length and ra number on the heat transfer results were discussed in this section. the results presented in this paper include the surface temperature distribution of the heated tube, local nu number and average nu number. the present experimental data covered a total of 40 test runs for five restrictions with different lengths of 600 mm (l/d=20), 900 yasin k. salman /al-khwarizmi engineering journal, vol.3, no.3, pp 3152 (2007) 39 mm (l/d=30), 1200 mm (l/d=40), 1500 mm (l/d=50), and 1800 mm (l/d=60) with the range of heat flux from 249 w/m2 to 1260 w/m2. surface temperature the distribution of the surface temperature along the tube axial distance may be affected by many variables such as the heat flux, and the restriction length. the surface temperature distribution for selected runs is plotted and shown in figs.2-6. the distribution of the surface temperature (ts) with tube axial distance for different heat fluxes and for all restriction lengths have the same general shape. the surface temperature distribution exhibits the following trend: the surface temperature gradually increases with the axial distance until a certain limit to reach a maximum value at approximately (x/d=5.84) beyond which it begins to decrease. this phenomenon, which can be explained as follows: at the entrance to the tube the thickness of the thermal boundary layer is zero. then, it gradually increases until the boundary layer fills the tube. from the entrance of tube to maximum point the heat transfer gradually decreases and (ts) gradually increases due to the laminarization effect in the near wall region (buoyancy effect) and due to the upstream axial conduction in the solid walls preheating the air in the restriction section and due to tube end losses. beyond the maximum point one would surmise that the surface temperature decreases along the axial distance. however, as the air is heated along the tube, its physical properties gradually change with the increased temperature. the thermal conductivity increases causing less resistance to the flow of heat and the viscosity increases causing radial flow of the hotter layers of air nearer to the surface to the tube center. a gradual increase of the local heat transfer beyond the maximum point must then be appeared. for constant wall heat flux this can only take place if the local differences between the bulk air temperature and the surface temperature decreases as shown in the distribution of (ts-x). fig. 2 shows the distribution of the surface temperature along the tube for different heat fluxes, for restriction with length of 600 mm (l/drest.=20). this figure reveals that the surface temperature increases at tube entrance to reach a maximum value after which the surface temperature decreases. this can also be attributed to the developing of the thermal boundary layer faster due to buoyancy effect as the heat flux increases, and as explained previously. fig. 3 is similar to fig. 2 but pertains to a restriction with length of 900 mm (l/drest.=30). the curves in the two figures show similar trend, but the surface temperature values in fig. 3 were higher than that observed in fig. 2 due to the length of restriction tube. figs. 4-6 were similar in trends to figs. 2-3 but pertains to restrictions with length of 1200 mm (l/drest.=40) in fig. 4, 1500 mm (l/drest.=50) in fig. 5 and 1800 mm (l/drest.=60) in fig. 6 respectively. fig. 7 shows the effect of variation of restrictions lengths on the tube surface temperature for high heat flux 1260 w/m2. it is obvious from that the surface temperature increases as the restriction length increases, as the heat flux is kept constant except the restriction section with length of 1200 mm (l/drest.=40) because it has the lowest surface temperature than other restriction sections. it is necessary to mention that the friction between the inside surface of the restriction length and the air flowing through it caused the temperature at entrance of the heated tube to be higher than the ambient temperature. it was also apparent from fig.7 that the lower values of the surface temperature take place in (l/drest.=40) and the higher values occur in yasin k. salman /al-khwarizmi engineering journal, vol.3, no.3, pp 3152 (2007) 40 (l/drest.=60) since the mass flow rate through the heated tube is the main parameter influencing the heat transfer results, so for the restriction tube with (l/drest.=40) gives smallest flow resistance and maximal mass flow rate and finally lower surface temperature. local nusselt number (nux) for free convection from a uniformly heated surface of length (l) exposed directly to the atmosphere, the average heat transfer coefficient for the whole length is calculated from: x l l x x 0 1h h dx l = ∫ = = …………………….(21) where: x sx bx q qh t t t∆ = = − ……… (22) (δt) in the above equation was taken as the difference between that local surface temperature (tsx) and the air temperature far away the effect of the surface. most of the previous workers mentioned in introduction section have calculated the heat transfer coefficient based on the temperature difference between the surface temperature and the fluid temperature at the entrance (ti) [i.e. (δt) = (tsx-tbi)]. in the present work, since the heat transfer surface is not exposed to the atmosphere (because the flow is confined). so that, the heat is transferred from the hot surface of the tube to the air flowing in it. thus, (δt)x cannot be taken equal to (ts-ti). it should be taken as (tsxtbx) where (tbx) is the local bulk air temperature in the cylinder. the distribution of the local nusselt number (nux) with the dimensionless axial distance (x/d) is plotted for selected runs and shown in figs. 8-14. figs. 8-12 show the effect of the heat flux variation on the nux distribution for the five restrictions lengths under consideration in the present work. it is clear from these figures that at the higher heat flux, the results of nux were higher than the results of lower heat flux. this may be attributed to the secondary flow effect that increases as the heat flux increases leading to higher heat transfer coefficient. therefore, as the heat flux increases, the fluid near the wall becomes hotter and lighter than the bulk fluid in the core. as a consequence, two upward currents flow along the sides walls, and by continuity, the fluid near the tube center flows downstream. figs. 13 & 14 show the effect of the restriction section length variation on the nux distribution with (x/d), for low heat flux 249 w/m2 and for high heat flux 1260 w/m2. for constant heat flux, the nux values give higher results for the restriction tube with length of 1200 mm (l/drest.=40) and the lower values occur in the restriction tube with length of 600 mm (l/drest.=20). this situation reveals that in (l/drest.=40) the flow will be faster and then it makes heat transfer enhancement rather than other restriction tubes as a result of density increasing and the buoyancy force decreasing which lead to change in the temperature gradient as well as change the volume of upward gases because of the flow area decreases with the increasing of the velocity of upward gases. in addition, since the velocity profile is fully developed at the entrance of the heated section, so the restriction tube will become as a resistance on the air flow and as the length to diameter ratio (l/d) of the restriction tube was higher, the flow resistance will be higher, so that the surface temperature will be higher, and this leads to lower values of nux when the restriction tube length increases. finally, the mass flow rate through heated tube which is the main parameter influencing the heat transfer results, causes the maximum heat yasin k. salman /al-khwarizmi engineering journal, vol.3, no.3, pp 3152 (2007) 41 transfer will be occurred in (l/drest.=40), which gives smallest flow resistance, maximal mass flow rate and higher heat transfer results. the presented results have shown qualitatively the same trend and behaviors as observed by he et al. (2004). average nusselt number ( nu ) the distribution of the average nusselt number with the dimensionless axial distance (x/d) is depicted for selected runs in figs. 15-16 which show the effect of the heat flux variation on the ( nu ) for restrictions with lengths of (l/drest.=20) and (l/drest.=40) respectively. the ( nu ) variation for other restriction lengths has similar trend as mentioned for (l/drest.=20) and (l/drest.=40). average heat transfer correlation the general correlation obtained from dimensional analysis for heat transfer by free convection available in incropera and dewitt (2003): n 1nu f ( gr, pr )= ………………(23) in the case of heat transfer from the inside surface of a vertical tube one expects that there is an effect of both length and diameter. for similarity with flat surface (which a cylinder of infinite diameter) the characteristic linear dimension in nu and gr numbers may be taken as the tube length (l) since the heated tube is vertically oriented. then equation (19) becomes: n l 2 lnu f ( gr , pr )= (24) the following correlations were obtained from the present work for each restriction length and a general correlation for all investigated cases was proposed and shown in fig. 17: 0.23 l lnu 0.88 ( ra )= for restriction with (l/d rest.=20) (25) 0.23 l lnu 1.024( ra )= for restriction with (l/d rest.=30) (26) 0.23 l lnu 1.068 ( ra )= for restriction with (l/d rest.=40) (27) 0.23 l lnu 1.036 ( ra )= for restriction with (l/d rest.=50) (28) 0.23 l lnu 1.042 ( ra )= for restriction with (l/d rest.=60) (29) 0.23 l lnu 1.263( ra )= for all restriction lengths (30) a comparison was made between the present case and with the vertical tube open at both ends without any restriction and with the case of putting the restriction tube at the entry of the heated tube as reported by salman and mohammed (2005) and this comparison was shown in fig. 17, the correlation obtained for the normal case as reported in mcadams (1954) and it has this form: 0.25 l lnu 0.59 ( ra )= (31) from the comparison, it is apparent that the restriction length and position have a significant effect on the heat transfer results. yasin k. salman /al-khwarizmi engineering journal, vol.3, no.3, pp 3152 (2007) 42 conclusions laminar free convection heat transfer from the inside surface of a uniformly heated vertical circular cylinder with different restriction lengths placed at the exit of the heat tube was experimentally performed. the following conclusions can be drawn from this work as: 1. the length of restriction tube provides a measure of the severity. an important finding of this study was that if the restriction exceeds a certain size, laminar upward flow throughout the whole of the heated part of the tube is tends to decrease the heat transfer results. this occurs if the ratio of the unheated length to the diameter of the tube (l/d) exceeds 40. 2. it was observed that the hot air near the heated wall aspirated the layers of hot air from the vertical tube. the uplift pressure and the tendency of the system were reached a balance because the air layers of the similar temperature and density were merged. however, this effect (similar to the movement of the hot air in a chimney) also found to be dependent on the intensity of the heat transfer. 3. the experimental results have revealed that the ratio of the axial length (l) to the diameter (d) affects the average heat transfer rate under the same conditions. within the range of l/drest.=20-60, the increase in l/d leads to decrease the heat transfer rate except the case of l/drest.=40. 4. for the same heat flux, the surface temperature values for restriction with (l/drest.=40) were lower than that for other restriction lengths. 5. for the same heat flux, the nux values for (l/drest.=40) were higher than that for other restriction lengths. 6. empirical equations in the form of log lnu versus log lra were obtained for each restriction length, eqs. 25-29, and a general correlation for all cases restriction lengths was proposed (eq. 30). 7. the comparison with the previous work shows that the restriction length and position has a significant effect on the heat transfer results. yasin k. salman /al-khwarizmi engineering journal, vol.3, no.3, pp 3152 (2007) 43 nomnclature as tube surface area, (m2) dimensionless group cp specific heat at constant pressure, (kj/kg.°c) gr: grashof number, g β l3(ts-ta)/ν 2 d tube diameter, (m) nu: nusselt number, h.l / k g gravitational acceleration, (m/s2) pr: prandtl number, µ . cp/k h heat transfer coefficient, (w/m2.°c) ra: rayleigh number, gr.pr i heater current, (ampere) x/d: dimensionless axial distance k thermal conductivity, (w/m.°c) l tube length, (m) subscript qcond. conduction heat loss, (w) a air qconv. convection heat flux, (w/m2) b bulk qconv. convection heat loss, (w) f film qt total heat input, (w) i inlet t temperature, (°c) v heater voltage, (volt) l m rest. based on tube length mean restriction s surface greek t total β thermal expansion coefficient, (1/k) w wall µ dynamic viscosity, (kg/m.s) x local ν ρ kinematic viscosity, (m2/s) air density, (kg/m3). superscript average yasin k. salman /al-khwarizmi engineering journal, vol.3, no.3, pp 3152 (2007) 44 1. restriction tube 2. shields 3. heated tube 4. teflon connection piece 5. exit teflon piece 6. thermocouples 7. mixing chamber fig. 1a the layout of experimental apparatus 1. heated tube 2. surface thermocouple 3. electric heater 4. asbestos layer 5. fiberglass layer 6. pair of thermocouples fig. 1b the heating arrangement yasin k. salman /al-khwarizmi engineering journal, vol.3, no.3, pp 3152 (2007) 45 3 8 13 18 23 280 5 10 15 20 25 30 x/d 60 100 140 180 220 80 120 160 200 ts ( c ) o lrest.= 900 mm q= 249 w/m^2 q= 389 w/m^2 q= 762 w/m^2 q= 996 w/m^2 q= 1260 w/m^2 fig.2 variation of the surface temperature with the axial distance for (l/drest.=20) fig. 3 variation of the surface temperature with the axial distance for (l/drest.=30) 1. heated tube 2. restriction tube 3. thermocouples 4. defcon adhesive fig. 1c the thermocouple locations along the heated tube 3 8 13 18 23 280 5 10 15 20 25 30 x/d 50 70 90 110 130 150 170 190 210 60 80 100 120 140 160 180 200 220 t ( c ) o s lrest.= 600 mm q = 249 w/m^2 q = 389 w/m^2 q = 762 w/m^2 q = 996 w/m^2 q = 1260 w/m^2 yasin k. salman /al-khwarizmi engineering journal, vol.3, no.3, pp 3152 (2007) 46 3 8 13 18 23 280 5 10 15 20 25 30 x/d 50 70 90 110 130 150 170 190 60 80 100 120 140 160 180 200 ts ( c ) lrest.= 1200 mm q = 249 w/m^2 q = 389 w/m^2 q = 762 w/m^2 q = 996 w/m^2 q =1260 w/m^2 3 8 13 18 23 280 5 10 15 20 25 30 x/d 40 60 80 100 120 140 160 180 200 220 240 ts ( c ) o lrest.= 1500 mm q= 249 w/m^2 q= 389 w/m^2 q= 560 w/m^2 q= 762 w/m^2 q= 996 w/m^2 q= 1260 w/m^2 3 8 13 18 23 280 5 10 15 20 25 30 x/d 50 75 100 125 150 175 200 225 250 275 ts ( c ) lrest. = 1800 mm q = 249 w/m^2 q = 389 w/m^2 q = 762 w/m^2 q = 996 w/m^2 q = 1260 w/m^2 3 8 13 18 23 280 5 10 15 20 25 30 x/d 110 130 150 170 190 210 230 100 120 140 160 180 200 220 240 ts ( c ) o q = 1260 w/m^2 (l/d)rest.= 40 (l/d)rest.= 20 (l/d)rest.= 30 (l/d)rest.= 50 (l/d)rest.= 60 fig.4 variation of the surface temperature with the axial distance for (l/drest.=40) fig.5 variation of the surface temperature with the axial distance for (l/drest.=50) fig. 6 variation of the surface temperature with the axial distance for (l/drest.=60) fig. 7 variation of the surface temperature with the axial distance for different restriction lengths yasin k. salman /al-khwarizmi engineering journal, vol.3, no.3, pp 3152 (2007) 47 7 8 9 2 3 4 5 6 7 8 9 2 3 4 1 10 x/d 25 75 125 175 225 275 325 375 0 50 100 150 200 250 300 350 400 n ux lrest.= 600 mm q = 249 w/m^2 q = 389 w/m^2 q = 762 w/m^2 q = 996 w/m^2 q = 1260 w/m^2 7 8 9 2 3 4 5 6 7 8 9 2 3 4 1 10 x/d 25 75 125 175 225 275 325 375 0 50 100 150 200 250 300 350 400 n ux lrest.=900 mm q = 249 w/m^2 q = 389 w/m^2 q = 762 w/m^2 q = 996 w/m^2 q = 1260 w/m^2 7 8 9 2 3 4 5 6 7 8 9 2 3 4 1 10 x/d 25 75 125 175 225 275 325 375 425 0 50 100 150 200 250 300 350 400 450 n ux lrest.= 1200 mm q = 249 w/m^2 q = 389 w/m^2 q = 762 w/m^2 q = 996 w/m^2 q = 1260 w/m^2 8 9 2 3 4 5 6 7 8 9 2 3 4 5 1 10 x/d 25 75 125 175 225 275 325 375 0 50 100 150 200 250 300 350 400 n ux lrest.=1500 mm q = 249 w/m^2 q = 389 w/m^2 q = 560 w/m^2 q = 996 w/m^2 q = 1260 w/m^2 fig. 8 variation of the local nusselt number with the axial distance for (l/drest. =20) fig. 9 variation of the local nusselt number with the axial distance for (l/drest. =30) fig. 10 variation of the local nusselt number with the axial distance for (l/drest. =40) fig. 11 variation of the local nusselt number with the axial distance for (l/drest. =50) yasin k. salman /al-khwarizmi engineering journal, vol.3, no.3, pp 3152 (2007) 48 8 9 2 3 4 5 6 7 8 9 2 3 4 5 1 10 x/d 0 25 50 75 100 125 150 175 200 225 250 275 300 n ux lrest.= 1800 mm q = 249 w/m^2 q = 389 w/m^2 q = 762 w/m^2 q = 996 w/m^2 q = 1260 w/m^2 8 9 2 3 4 5 6 7 8 9 2 3 4 1 10 x/d 50 70 90 110 130 150 170 190 40 60 80 100 120 140 160 180 200 n ux q = 249 w/m^2 (l/d)rest.= 20 (l/d)rest.= 30 (l/d)rest.= 60 (l/d)rest.= 50 (l/d)rest.= 40 7 8 9 2 3 4 5 6 7 8 9 2 3 4 1 10 x/d 125 175 225 275 325 375 100 150 200 250 300 350 n ux q = 1260 w/m^2 (l/d)rest.= 60 (l/d)rest.= 50 (l/d)rest.= 30 (l/d)rest.= 20 (l/d)rest.= 40 7 8 9 2 3 4 5 6 7 8 9 2 3 4 1 10 x/d 25 75 125 175 225 275 325 375 0 50 100 150 200 250 300 350 n u lrest.= 600 mm q = 249 w/m^2 q = 389 w/m^2 q = 560 w/m^2 q = 996 w/m^2 q = 1260 w/m^2 fig. 12 variation of the local nusselt number with the axial distance for (l/drest. =60) fig. 13 variation of the local nusselt number with the axial distance for different restriction lengths fig. 14 variation of the local nusselt number with the axial distance for different restriction lengths fig. 15 variation of the average nusselt number with the axial distance for (l/drest. =20) yasin k. salman /al-khwarizmi engineering journal, vol.3, no.3, pp 3152 (2007) 49 7 8 9 2 3 4 5 6 7 8 9 2 3 4 1 10 x/d 25 75 125 175 225 275 325 375 425 0 50 100 150 200 250 300 350 400 n u lrest.=1200 mm q = 249 w/m^2 q = 389 w/m^2 q = 762 w/m^2 q = 996 w/m^2 q = 1260 w/m^2 9.34 9.38 9.42 9.46 9.50 9.54 9.589.36 9.40 9.44 9.48 9.52 9.56 log (ral) 1.00 1.40 1.80 2.20 2.60 3.00 3.40 1.20 1.60 2.00 2.40 2.80 3.20 3.60 lo g (n ul ) nul= 1.289 (ral)^0.23 the present work nul= 1.248 (ral)^0.23 (salman & mohammed, 2005) nul= 0.59 (ral)^0.25 (mcadams, 1954) references abd-el-malek b. m. and nagwa a. b. (1991)”group method analysis of steady free-convective laminar boundary-layer flow on a nonisothermal vertical circular cylinder” j. of computational and applied mathematics, vol.36, no. 2 , pp. 227-238. al-arabi m.; khamis m. and abd-ul-aziz, (1991)”heat transfer by natural convection from the inside surface of a uniformly heated vertical tube”. int. j.heat and mass, vol.34, no.4/5, pp.10191025. chang c. j.; lin t. f. and yan w. m. (1986) “natural convection flows in a vertical, open tube resulting from combined buoyancy effects of thermal and mass diffusion” international j. of heat and mass transfer ,vol.29, no.10, pp.1543-1552. dyer j.r., (1975)”the development of laminar natural convective flow in a vertical uniform heat flux duct”. int. j. heat and mass transfer, vol.18, pp.14551465. fukusako s. and takahashi m. (1991) “free convection heat transfer of air-water layers in a horizontal cooled circular tube“ int. j. of heat and mass transfer, vol. 34, no. 3, pp.693-702 he y. l.; tao w. q.; qu z. g. and chen z. q. (2004)“steady natural convection in a vertical cylindrical envelope with adiabatic lateral wall “int. j. of heat and mass transfer, vol. 47, no. 14-16, pp.31313144. hess c.f. and miller c.w., (1979)” natural convection in a vertical cylinder subject to constant heat flux”. int. j. heat and mass transfer, vol.22, no.3, pp.421430. fig. 16 variation of the average nusselt number with the axial distance for (l/drest. =40) fig. 17 correlation of the average heat transfer results and compared with available literature yasin k. salman /al-khwarizmi engineering journal, vol.3, no.3, pp 3152 (2007) 50 holman j.p. (2001) “experimental methods for engineers” 7th edition, mcgraw-hill international edition, new york, usa. incropera f. p. and dewitt d. p. 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(2005) “experimental investigation of natural convection from vertical and horizontal helicoidal pipes in hvac applications “ energy conversion and management ,vol. 46, no.18-19, pp.2996-3013. oliver d. r. (1962) “the effect of natural convection on viscous-flow heat transfer in horizontal tubes “chemical engineering science ,vol. 17, no.5, pp.335-350. popiel c. o. and wojtkowiak j. (2004) “experiments on free convective heat transfer from side walls of a vertical square cylinder in air” experimental thermal and fluid science, vol.29, no.1 , pp.1-8. salman y.k. and mohammed h.a. (2005) “the effect of restriction shape on laminar natural convection heat transfer in a vertical circular tube” al-khawarizmi engineering journal, vol. 1, pp.83-100. selver r., kamotani y., ostrach s., (1998) “natural convection of a liquid metal in vertical circular cylinders heated locally from the side” j. of heat transfer asme transactions, vol.120, pp. 108-114. shenoy, a. v. (1984)“natural convection effects on heat transfer to power-law fluids flowing under turbulent conditions in vertical pipes” int. communications in heat and mass transfer ,vol.11, no.5, pp.467-476. shigeo k. and adrian b. (1980)“experimental study of natural convection in a horizontal cylinder with different end temperatures” int. j. of heat and mass transfer ,vol. 23, no.8, pp. 11171126. vinokurov v. f., volkov s.v., martynenko o. g., khramtsov p. p. and shikh i. a. (1993) “some aspects of free-convective heat transfer in eddy flow through a horizontal tube” int. j. of heat and mass transfer, vol.36, no.18 , pp.44874491. yasin k. salman /al-khwarizmi engineering journal, vol.3, no.3, pp 3152 (2007) 51 wojciech t. k. (2000) “natural convection heat transfer around horizontal tube in vertical slot “ int. j. of heat and mass transfer ,vol. 43, no.3 ,pp. 447-455. yan w. m. and lin t. f. (1991)“theoretical and experimental study of natural convection pipe flows at high rayleigh number” int. j. of heat and mass transfer, vol.34, no.1, pp.291-303. yissu w. (1995) “laminar natural convection in vertical tubes with one end open to a large reservoir” int. j .of heat transfer, vol. 56-06, section: b, pp.3411. cengel y.a. (2004) “heat transfer a practical approach” mcgraw-hill international, 3rd edition, new york, usa. yasin k. salman /al-khwarizmi engineering journal, vol.3, no.3, pp 3152 (2007) 52 انتقال الحرارة بالحمل الحر باستخدام مقاطع مختلفة االطوال وموضوعةعند مخرج انبوب دائري شاقولي معرض لفیض حراري ثابت یاسین خضیر سلمان.د حسین احمد محمد كلیة الھندسةكلیة الھندسة/ / امعة بغداد امعة بغداد جج كلیة الھندسةكلیة الھندسة/ / جامعة بغداد جامعة بغداد قسم المیكانیكقسم المیكانیك القسم النوويالقسم النووي ::الخالصةالخالصة یتن اول البح ث دراس ة عملی ة النتق ال الح رارة بالحم ل الح ر لجری ان الھ واء الطب اقي ف ي داخ ل أنب وب دائ ري ش اقولي صمم الجھاز العمل ي ).ُ 5 10*٩(إلى ) 6.9 108*(من ) ral(حراري ولمدى تغیر لرقم رایـلي باستخدام شرط ثبوت الفیض ال على درج ة الح رارة , الموضوع في مدخل األنبوب وفي الموقع العلوي ألنبوب التسخین) restriction(إلیجاد تأثیر طول المقید والمع دل ) nux(الت الي عل ى تغی ر رق م نس لت الم وقعي على طول سطح األنبوب المسخن وكذلك على معام ل انتق ال الح رارة وب )nu( . الجھ از العمل ي المس تخدم یتك ون م ن أنب وب م ن االلمنی وم مس خن حراری ًا بط ول )900mm ( وبقط ر داخل ي )30mm .( لك ن ب أطوال مقیدات الدخول تتضمن أنبوب دائري أسطواني لھ نفس القط ر ال داخلي ألنب وب التس خین و), 1500 mm, 1200 mm, 900 mm, ,600 mm١٨٠٠ mm( , لقد وجد من خالل النتائج العملیة أن درجة الحرارة عل ى ط ول س طح األنب وب تك ون أعل ى م ا یمك ن للمقی د ال ذي طول ھ )1800 mm ( وتكون اقل ما یمكن للمقید الذي طولھ)1200 mm .( أظھرت النتائج أن قیم رقم نسلت الموقعي)nux (والمعدل )nu( تكون أعلى ما یمكن للمقید الذي طولھ)1200 mm ( وتكون اقل ما یمكن في حال ة المقی د ال ذي طول ھ)1800 mm .( لق د lnu(بش كل ) empirical equations(ت م الحص ول عل ى مع ادالت تجریبی ة log ( ض د) lra (log لك ل حال ة م ن .الحاالت المستخدمة في البحث وكذلك تم الحصول على معادلة عامة تربط جمیع الحاالت ((study the influence of forming condiutians like determation speed on void closure in open die forgins)) 106 al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 4, no. 4, pp 106-121 (2008) study the influence of forming conditions like deformation speed on void closure in open die forging alaa hassan ali department of materials engineering/ university of technology (received 10 june 2007; accepted 10 september 2008) abstract this paper presents an investigation to the effect of the forming speed on healing voids that inhabit at various size in an ingot. the study was performed by using finite element method with bilinear isotropic material option, circular type voids were considered. the closure index was able to predict the minimum press force necessary to consolidate voids and the reduction. the simulation was carried out, on circular cross-section lead specials containing a central void of different size. at a time with a flat die, different ratio of inside to outside radius was taken with different speed to find the best result of void closure. keywords: 1. introduction: casting is the method used to shape bulk of engineering materials due to simplicity and possibility of casting large products. the defects in casting are shrinkage, gas porosity, hot tears, alloy segregation and inclusions [1]. the defects by solidification shrinkage and gas porosity are relatively different to control. the void formed in the product must be eliminated by the application of compression loads compatible with plastic deformation. forging is classified as closed die and open die forging. in closed die forging, a compressive force is applied on the work piece and forced to take the shape of the die surface or impression. open die forging is a process used to produce huge turbine shafts, nuclear reactors, vessels and pressure value [2]. these parts should have good toughness and fatigue strength. most failures of engineering components can be initiated by concentration of stresses of internal microscopic voids or inclusions, therefore the strategy is to close and consolidate these internal defects completely [3]. closure of voids and consolidation of internal defects is a very significant issue for some reasons like void constitutes the weakest portion of the component, and act as stress raisers, which promote fatigue. the finite element method (fem) is a comprehensive tool which is flexible and capable of tracing material flow and able to investigate contours of stresses and strain, even in cases of linear and non-linear material properties [4]. 2. theoretical consideration and analysis: the efficient method of analysis for metal forming should be capable of predicting the effect of various parameters on metal flow characteristics [5]. in this regard, the rigid viscoplastic defect formation in metal forming. in simulating, the void closure in forging the assumptions taken for the material and the process such as an isotropic and homogenous, rigid perfectly plastic, the friction between the work piece and the die is considered to obey coulomb friction low (sliding only), plane strain and isothermal process. for (2d) finite element surface to surface analysis, ansys software utilizes two distinct contact surfaces, the rigid surface referred to as” target" surfaces which is modeled with element type alaa hassan ali al-khwarizmi engineering journal, vol.4, no.4, pp 106-121 (2008) 107 "targe 169" or the deformable body surface is referred as” contact" element type contact for 2d . large strain solid the element type visco 106 is used (four-node nonlinear solid). for quadrilateral element, the displacements are interpolated as follows [6]: uiniu    4 1 …)1(    4 1i niviv …)2( strains are obtained from the displacements: ui i x ni x u x         4 1  …)3( vi i y ni x v y         4 1  …)4(          4 1 ( ixy u xy v  )viui x ni y ni      …(5(                                                        x n y n x n y n x n y n x n y n y n y n y n y n x n x n x n x n 44332211 4321 4321 0000 0000 …(6) where ni=shape function for the node i n1= (1ζ ) ( 1η ), n2=ζ( 1η ), n3= ζ η and n4=η (1ζ )  xyyx    …(7)  44332211 vuvuvuvu   …(8) equation (6) can be expressed as:    .b …(9)  dbd   …(10)                    2 21 00 01 01 )1)(1(     e d …(11) strain energy u = dxdydz t   2 1 …(12) hence u = dxdydzdbb t  )( 2 1   by substitution of equation (2) and (10) into (12) u dxdydzbdb t    2 1 …(13) also, the work done by external forces , w= f t  …(14) the total potential energy for the element wu  … (15) fdxdydzdbb ttt     2 1 …(16) applying the minimum energy theorem, 0     x equation (16) becomes: 0  fdxdydzbdb t  …(17) fke    …(18) where dxdydzbdbek t   for plane strain; dz = constant =t (element thickness) thus dbdxdytbek t   …(19) in large stain solids the cauchy stress σ in equation 10 is decomposed into deviatory part plus pressure part:  pq     …(20)     cauchy stress deviator  q [ 1 11 0 0 0 ]           3 zyx p  . the pressure is independently interpolated. alaa hassan ali al-khwarizmi engineering journal, vol.4, no.4, pp 106-121 (2008) 108 3. simulation and results: the closure and pressing force plot, versus displacement are used to investigate the effect of different speed on closure of voids located at specified positions singly at a time and collectively. in forging process, the important step is the step where the void is healed completely such that avert the possibility of reopening of void during manipulation process. accordingly, the simulation where made up to the instant of closure of voids. the model built as a half of circle containing a central void as shown in fig. (1), the simulation procedures taken according to the following conditions: 1. taken the void as central void of the cylindrical ingot with 0.2 ratio of the inner to outer radius and different speeds of closure as follows: aspeed of 0.2 mm/min the results are shown in figs. ( 2, 3, 4, 5, 6, 7 ) bspeed of 2 mm/min the results are shown in figs. ( 8, 9, 10, 11, 12, 13, 14, 15, 16 ) cspeed of 20 mm/min the results are shown in figs. ( 17, 18, 19, 20, 21, 22, 23, 24, 25 ) 2. taken the void as a central void of the cylindrical ingot with 0.3 ratio and the different speeds of closure representative as follows: aspeed of 0.2 mm/min the results are shown in figs. (26, 27, 28, 29, 30, 31, 32, 33, 34) bspeed of 2mm /min the results are shown in figs. (35, 36, 37, 38, 39, 40, 41) cspeed of 20 mm/min the results are shown in figs. (42, 43, 44, 45, 46, 47, 48, 49, 50) 3. taken the void as a central void of the cylindrical ingot with of 0.4 ratio with the different speeds of closure as follows: aspeed of 0.2 mm/min the results are shown in figs. (51, 52, 53, 54, 55, 56, 57, 60, 61) bspeed of 2 mm/min the results are shown in figs. (62, 63, 64, 65, 66, 67, 68, 69) cspeed of 20 mm/min the results are shown in figs. (70, 71, 72, 73, 74, 75, 76, 77, 78) 4. figures (a to d) represent the relation between the speed and displacement in (y) direction, stress ( y ), strain and hydrostatic pressure for all ratio. 4. discussions and conclusions: the results can get from the above figures summarized as follows: 1from the force – displacement curves, it can be observed that: afor void closure decrease with increase the ratio with the same closure speeds, this shown in figs. (2, 8, 17). bwith the same ratio the closure speed increase with increase of closure displacement, this shown in figs. (26, 35, 42), and also the same results of others ratio shown in figs. (51, 62, 70). 2the von misses equivalent stress ( e ) for each ratio with different speeds can be shown in figs. (4, 11, 20, 29, 37, 45, 54, 65, 73), highest stress concentrated near central void for highest closure speed (20 mm/min) for all ratios and also highest void closure. 3for the deformation in (y) direction (uy) for all ratios are shown in figs. (3, 10, 19, 28, 36, 48, 57, 66, 75), it can be observed that highest deformation concentrated at the bottom of the ingot with highest speed at all ratios stages which cause best void closure with highest speed and ratio. 4when compare the result shown in figs.(16, 25, 34, 42, 54, 63, 72, 81) for strain in (y) direction it can observed with same conditions that the highest ( y ) happened on the highest speed at highest third ratio which also cause highest void closure . 5the same result also confined to the hydrostatic pressure shown in figs. (7, 14, 23, 32, 40, 52, 61, 70, 79), it is observed that the highest pressure concentrated also in the bottom of the ingot and at the edge of the central void with highest void closure also. 6from the points mentioned above it can be conclusion that the voids healed by the best result when used high speed with highest ratio of central void radius to outer radius of cylindrical ingot. 7figures a to d shows the relation of the speed with displacement in y direction in fig. (a) which shows that the increasing of displacement occurs with increasing the speed at highest ratio. fig. b shows that the more the speed the more the stress at maximum ratio. the same behavior occurs in fig. c & d that with increasing of speed cause increasing each of strain and hydrostatic pressure at highest ratio also. 109 fig.a. speed & displacement (y). fig. b. speed & stress (y) fig. c. speed & strain (y). 0 5 10 15 20 25 1 2 3 4 speed stress(ratio 0.2) stress (ratio 0.3) stress (ratio 0.4) 0 5 10 15 20 25 1 2 3 4 speed displacement (ratio 0.2) displacement (ratio0.3) displacement (ratio 0.4) 0 5 10 15 20 25 1 2 3 4 speed strain (ratio 0.2) strain (ratio 0.3) strain (ratio 0.4) alaa hassan ali al-khwarizmi engineering journal, vol.4, no.4, pp 106-121 (2008) 110 fig. d. speed & hydrostatic pressure. fig. 1 fig. 2 fig. 3 fig. 4 fig. 5 fig. 6 0 5 10 15 20 25 1 2 3 4 speed h.pressure (ratio 0.2) h.pressure (ratio 0.3) h.pessure (ratio 0.4) alaa hassan ali al-khwarizmi engineering journal, vol.4, no.4, pp 106-121 (2008) 111 fig. 7 fig. 8 fig. 9 fig. 10 fig. 11 fig. 12 fig. 13 fig. (14) alaa hassan ali al-khwarizmi engineering journal, vol.4, no.4, pp 106-121 (2008) 112 fig. 15 fig. 16 fig. 17 fig. 18 fig. 19 fig. 20 fig. 21 fig. 22 alaa hassan ali al-khwarizmi engineering journal, vol.4, no.4, pp 106-121 (2008) 113 fig. 23 fig. 24 fig. 25 fig. 26 fig. 27 fig. 28 fig. 29 fig. 30 alaa hassan ali al-khwarizmi engineering journal, vol.4, no.4, pp 106-121 (2008) 114 fig. 31 fig. 32 fig. 33 fig. 34 fig. 35 fig. 36 fig. 37 fig. 38 alaa hassan ali al-khwarizmi engineering journal, vol.4, no.4, pp 106-121 (2008) 115 fig. 39 fig. 40 fig. 41 fig. 42 fig. 43 fig. 44 fig. 45 fig. 46 alaa hassan ali al-khwarizmi engineering journal, vol.4, no.4, pp 106-121 (2008) 116 fig. 47 fig. 48 fig. 49 fig. 50 fig. 51 fig. 52 fig. 53 fig. 54 alaa hassan ali al-khwarizmi engineering journal, vol.4, no.4, pp 106-121 (2008) 117 fig. 55 fig. 56 fig. 57 fig. 58 fig. 59 fig. 60 fig. 61 fig. 62 alaa hassan ali al-khwarizmi engineering journal, vol.4, no.4, pp 106-121 (2008) 118 fig. 63 fig. 64 fig. 65 fig. 66 fig. 67 fig. 68 fig. 69 fig. 70 alaa hassan ali al-khwarizmi engineering journal, vol.4, no.4, pp 106-121 (2008) 119 fig. 71 fig. 72 fig. 73 fig. 74 fig. 75 fig. 76 fig. 77 alaa hassan ali al-khwarizmi engineering journal, vol.4, no.4, pp 106-121 (2008) 120 5. nomenclatures: a0 initial area (m 2 ) ai area at instance i (m 2 ) b strain displacement relationship matrix b transpose of strain – displacement relation matrix d material properties matrix dmx max – displacement et element type e young’s modulus (n/m 2 ) fx/fy external applied forces (n) k bulk modules (n/m 2 ) ke stiffness matrix for element e n number of nodes px,py pressure in direction x & y (n/m 2 ) pi pressure at instant i (n/m 2 ) smin,smax minimum & maximum stress t thickens of the specimen (m) t time (sec) e strain vector s displacement vector (u1, v1, u2, v2, u3, v3, u4,v4) m x functional u total energy (joule) q unit matrix e equivalent stress (n/m 2 ) 6. references: [1] charles barre “hip increasing by used for upgrade of casting as process becomes economical “reprint from incast. august, 1998, kitty hawk product,1165,monarch st. garden. [2] dudra ,steve and taek, yong “ analysis of void closure “int. j. of machine tools manufacture pp.711-780 (1982) . [3] sun jie –xian “analysis of special forging processes for heavy ingot by finite element method “ int. j. mach .tools manufacture vol. 28, no. 2 pp 173-179,1988. [4] oh,s. i,” finite element analysis of metal forming processes with arbitrary shaped dies “ int. j. mech. sci. vol. 24, no. 8 pp. 479-491 (1982) . [5] mujkwan kak ajang “the effect of die shape on void closure in open die forging “ phd thesis, september ,2002. [6] cook,robert, d. “finite element modeling for stress analysis" 1995, john willy and son. inc., new york. alaa hassan ali al-khwarizmi engineering journal, vol.4, no.4, pp 106-121 (2008) 121 تأثير شروط التشكيل مثل السرعة على غلك الفجوات بقوالب الطرق المفتوحة عالء حسن علي انجايعت انخكنىنىجٍت / لسى هنذست انًىاد الخالصة ولذ حى اسخخذاو طزٌمت انعناصز انًحذدة فً , ٌمذو هذا انبحث دراست فً حاثٍز انسزعت عهى غهك انفجىاث بًخخهف أحجايها فً انًصبىباث حى انخحهٍم عهى اساس ثنائً األبعاد . انخحهٍم وحًج عًهٍت انخًثٍم نًمطع اسطىانً نًصبىبت ححخىي عهى حجاوٌف يزكزٌت يخخهفت األحجاو . وحى انحصىل عهى اننخائج ألغزاض انًمارنت وإٌجاد أفضم انغالق نهفجىة باحجاو يخخهفت وسزع حشكٍم يخخهفت, باسخخذاو لانب طزق يفخىح al-khwarizmi al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 5, no. 3, pp 72 76 (2009) removal of sulfate from waste water by activated carbon mohammed sadeq salman computer centre/ university of baghdad (received 23 february 2009; accepted 6 september 2009) abstract activated carbon was produced from coconut shell and was used for removing sulfate from industrial waste water in batch processes. the influence of various parameter were studied such as ph (4.5 – 9.) , agitation time (0 – 120)min and adsorbent dose (2 – 10) gm. the langmuir and frandlich adsorption capacity models were been investigated where showed there are fitting with langmmuir model with squre regression value ( 0.76). the percent of removal of sulfate (22% 38%) at (ph=7) in the isotherm experiment increased with adsorbent mass increasing. the maximum removal value of sulfate at different ph experiments is (43%) at ph=7. keywords: waste water, adsorption , activated carbon 1. introduction water pollution by anions is not only a public health concern ; therefore removal of these ions from waste water before the process of discharging is very important . sulfate (so4 ) is widely distributed in natural water or industrial waste water for example waste water of charging process in manufacturing of batteries. this practice often produces a waste water containing sulfuric acid that is usually neutralized by addition of sodium hydroxide or sometime quick lime (cao) prior to release to a receiving stream which could contain high sulfate and other ions.(namasivayam and sangeetha 2007). there are several technologies for sulfate treatment like chemical precipitation in order to sediment the sulfate as undissolved salt as evaporation , which reduce the volume of waste water with high concentration of sulfate or ion exchange and reverse osmosis.(minnesota d. of health 2008) adsorption is a demonstrated waste water treatment that use solid adsorbent to remove dissolved pollutants from waste water.(john and barry 1998) one of the well known adsorbent is activated carbon which is made from many carbonaceous source including coal, coke, pest, wood and coconut shell. the carbon source material is activated by treating it with an oxidizing gas to form a highly porous structure with a large internal surface area. the forms of activated carbon are granular activated carbon (gac) or powdered activated carbon (pac). the carbon adsorption mechanism is complicated and although the attraction is primarily physical is a combination of physical , chemical and electrostatic interaction between the activated carbon and the pollutant (essam 1995). during the process of adsorption there many parameter affect on the adsorption capacity such as ph number which represented the [h] concentration , contact time where increasing of contact time will increase of adsorption capacity , mass of adsorbed , temperature and concentration of adsorbate (pollutant) .(namasivayam and sangeetha 2007). the use of activated carbon to remove inorganic pollutants from waters is widely extended , because of their high surface area, micro porous character and the chemical nature of their surface (zhimang et al. 2005). ahmed a. moosa al-khwarizmi engineering journal, vol. 5, no. 3, pp 72 76 (2009) 73 langimuir model is used to fit the any result with the any model according to the equation(1) by plotting ce vs ce/qe . (john, 1995) a ce abqe ce  1 ...(1) where ce is the concentration of sulfate at equilibrium (mg/l) , a is constant monolayer adsorption capacity (mg/g) b is constant related to energy of adsorption (l/g) qe is adsorption capacity (mg/g). frandich model is expressed to fit the result as shown is equation (2) by plotting log qe vs log ce . (john, 1995) ncekqe   …(2) linearization of (eq 2) gives: log qe = log k + 1/n log ce ...(3) where n and k are constants, qe is adsorption capacity(mg/g) and ce is sulfate concentration at equilibrium (mg/l). the aim of this study is investigating of sulfate removal from waste water by using activated carbon in batch experiment and the result of equilibrium have been detected with above modeling equation (1 , 2). 2. experimental procedure 2.1 material and method adsorbent is activated carbon is produced from coconut shell by (unicarbo. company italia) with properties are shown in table 1 table 1, characteristic of activated carbon item characteristic specific surface area (m2/g) 1000 – 1100 ash content % 3.2 5% specific gravity 1.29 bulk density kg/m3 0.12 porosity % 92% adsorbate is waste water was obtained from batteries factory – waste water from charging unit with concentration (500-600) ppm which had been diluted to desired concentration with distilled water. analysis of stock and samples had been investigated by colorimetric type (color spec, uk) at wave length (420)nm soaad and mohammed 1990). 3. adsorption studies 3.1 effect of adsorbent mass adsorption experiment was carried out by different weight of adsorbent (2 , 4 , 6 , 8 , 10) gm of activated carbon in 5 flasks each one size 250 ml contains 100 ml of waste water with (520 mg/l) of sulfate concentration after shaking for 4 hours at ph 7 – 8 and 25 c 0 by using shaker type (ht, infors, trm, ger), at speed 350 rpm . the sample of each flask was filtrated by paper filter and analysis for sulfate concentration by colorimetric method. (soad and mohammed, 1990). 3.2 effect of ph and time contact three experiments were carried at different ph (5– 4.5) , ( 7) and (9) by agitating 600 ml of adsorbate at 150 gm/l sulfate concentration with 10 gm of activated carbon at 25 c 0 and 350 rpm and for 3 hour to express the effect of ph on the adsorption capacity . adjusting of ph by using diluted hcl and naoh . with ph meter type (metrdlm, 650,swiss) the sampling were obtain with time internal (15, 30, 60, 90, 120) min and analyses for sulfate concentration. 4. result and discussion 4.1 adsorption isotherm. fig. (1) show the decreasing equilibrium concentration for experiment of different weight of adsorbent due to the increasing of surface of adsorption (martin and albahrani 1978 ). fig. (2) shows the adsorption capacity (eq 4) according to equilibrium concentration plotting by qe vs ce which show low capacity value due to the surface of carbon is effected by other ions in the waste water. ahmed a. moosa al-khwarizmi engineering journal, vol. 5, no. 3, pp 72 76 (2009) 74 1000 v m cec qe    …(4) where c: initial conc. (mg/l) ce: equilibrium conc. (mg/l) m : mass of activated carbon (g) qe : adsorption capacity (mg/g) v : volume of sample (ml) 0 50 100 150 200 250 300 350 400 450 0 2 4 6 8 10 12 mass of activated carbon mg e q u li b r u im c o n c . o f s u lf a t e m g /l fig.1. equilibrium concentration of sulfate at different adsorbent mass. 0 1 2 3 4 5 6 7 250 300 350 400 450 500 ce mg/l q e m g /g fig.2. equilibrium isotherm curve. ce/qe vs ce curve was plotted to determine langmuir constants (a, b) in fig. (3). y = -0.9703x + 482.58 0 20 40 60 80 100 120 140 160 180 250 300 350 400 450 ce mg/l c e /q e g m /l fig.3. langmuir equilibrium isotherm. when plotting of log ce vs log qe to determine frandlich constant constants n and k adsorption coefficient in fig. (4) which show unfitting results because n value less than (>1).(abood 2005). y = 3.9249x 9.5659 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 2.48 2.5 2.52 2.54 2.56 2.58 2.6 2.62 log ce l o g q e fig.4. frandlich equilibrium isotherm. 4.2 ph and contact time effect fig. (5) shows percent of removal of sulfate for each ph value at different time. which show the critical value and the best value of removing at ph(7) after (30) min. 60 70 80 90 100 110 120 130 140 0 20 40 60 80 100 120 140 contact time (min) s u lf a te c o n c . m g /l ph 4.5 5 ph 7 ph 9 fig.5. effect of ph on sulfate cons. fig.(6) shows the comparing among experimental isotherm and theoretical isotherm ( langmuir and frandlich models) with error percent value for each models. (abood 2005) equation (5). ahmed a. moosa al-khwarizmi engineering journal, vol. 5, no. 3, pp 72 76 (2009) 75      1 exp exp cal qe qeqe n ...(5) where n= number of samples qeexp= experimental adsorption capacity (mg/g) qecal= calculated adsorption capacity by models (mg/g) 0 1 2 3 4 5 6 7 300 350 400 450 ce mg/l q e m g / g experimental isotherm langmiur model isotherm frandlich model isotherm fig.6. experimental and theoretical isotherms. the models constants are showed in table (2) with e value for both models. table 2, langmuir and frandlich constant models a (mg/g) b (l/g)×10 -3 k (mg/g) 1/n %e langmuir 1.03 2 13.6 frandlich 1.47 3.925 27.4 5. conclusions  the effect of ph value showed the adsorption of sulfate is like ion exchange process due to the activated carbon particles is considered with positive charge and so4 ion is a negative charge therefore the adsorption will be caused by the different charges.  adsorption followed langmuir isotherm more than frandlich isotherm with error percent (%e) values were in langmuir model less than in frandlich model.  adsorption of sulfate with activated carbon is higher at low concentration than the high concentration . nomenclature a langumir constant (eq. 1) (mg/g) b langumir constant (eq. 1) (l/g) ce equilibrium concentration (mg/l) e error value among experimental and theoretical k frandlich constant (eq. 2) (mg/g) m mass of activated carbon (gm) n frandlich constant (eq. 2) qe adsorption capacity at equilibrium (mg/g) 6. references [1] abood w. thesis. "removal of furfural by activated carbon" baghdad university. college of engineering , 2005. [2] essam almajid ,"environment engineering" jordan 1995. [3] john g "adsorption technology and design " wiley series , uk,1995. [4] martin r. and albahrrani k., "experimental of factor influencing adsorption", water research, vol. 12 , pp 879-888 , 1978. [5] minnesota dept. of health report "sulfate in well water" 2008. [6] namasivayam , d. sangeetha, "coconut coir pith for the removal of sulfate", j. of desalination, vol. 219 , pp 1 – 13 , 2008. [7] soaad a .abaawy and mohammed s. hussn , "water tests" al musel university, iraq, 1990 [8] john and barry c. "adsorption technology and design", oxford, uk, 1998. [9] zhimang g. ,jun f. and baolin deng , "preparation and evaluation of gac based iron contain adsorbent for arsenic removal" environ. sci. technol ,vol 39, pp. 3833 – 3843 , 2005. 76 72، صفحة 3، العذد 5هجلة الخوارزهي الهنذسية الوجلذ هحوذ صادق سلواى (200 9) 76 إزالة الكبريتات هي الوياه الوخلفة باستخذام الفحن الونشط هحوذ صادق سلواى جاهعت بغذاد/ هركس الحاسبت االلكخروًيت الخالصة . الكبريخاث هي الوياٍ الصٌاعيت في حجارب البحثإزالتحن اسخخذام الفحن الوٌشط هجهس هحليا هي أصل قشىر جىز الهٌذ في عوليت . دقيقت (120 – 0)وزهي الخالهس (9 – 4.5)غن والذالت الحاهضيت (10 – 2)الوخغيراث في الخجربت هي وزى الفحن r)حوج الوطابقت هع هىديليي الًكوير وفراًذلش ولىحظ اى هٌحٌي الخىازى يخطابق هع هىديل الًكوير بـ 2 وال يخطابق هع فراًذلش (0.76= فأى . هع زيادة وزى الفحن الوسخخذم في عوليت حجربت هٌحٌي الخىازى (%38)الى (%22)هي هي ( (ph=7 عٌذها حكىى اإلزالتواى ًسبت . %(. 43)في حالت حغيير زهي الخالهس هى (ph=7) عٌذ إزالت أفضل 1018 al-khwarizmi engineering journal al-khwarizmi engineering journal,vol. 12, no. 3, p.p. 1018 (2016) produced water treatment using ultrafiltration and nanofiltration membranes bashir y. sherhan1* areej d. abbas1** qusay f. alsalhy1*** thamera k. abbas2 yusra m. mahdi2 noura a. abdul kareem2 alaa a. rashad2 zahraa w. rashad2 aiden a. shawkat2 1membrane technology research unit/ department of chemical engineering / university of technology 2chemical and petro-chemical research center/ the industrial r and d/ ministry of industry and minerals/ iraq *email:bashiryoush1974123@yahoo.com **email: areej_dalf@yahoo.com ***email: qusay_alsalhy@yahoo.com (received 13 january 2016; accepted 14 april 2016) abstract the application of ultrafiltration (uf) and nanofiltration (nf) processes in the handling of raw produced water have been investigated in the present study. experiments of both ultrafiltration and nanofiltration processes are performed in a laboratory unit, which is operated in a cross-flow pattern. various types of hollow fiber membranes were utilized in this study such as poly vinyl chloride (pvc) uf membrane, two different polyether sulfone (pes) nf membranes, and poly phenyl sulfone ppsu nf membrane. it was found that the turbidity of the treated water is higher than 95 % by using uf and nf membranes. the chemical oxygen demand cod (160 mg/l) and oil content (26.8 mg/l) were found after treatment according to the allowable limits set by means of world health organization who water quality standards. the final composition of so4 -2 (110 mg/l) and no3 (48.4 mg/l) components within the produced water after treatment were agreed with the permissible limits of who, whereas cl-1 (8900 mg/l) component is not in the allowable limits. finally by the use of pvc, pes and ppsu hollow fiber membranes; this method is seen to be not sufficient to remove the salinity of the produced water. keywords: ultrafiltration membrane, nanofiltration membrane, oily wastewater, produced water, desalination. 1. introduction in fact the importance of the use of both nanofiltration (nf) and ultrafiltration (uf) membranes for separation processes are hastily growing and extending to include vast field of industrial applications. among the industrial application of uf and nf, the treatment of produced water is dominated to remove the oil, suspended solid, and organic compounds [1,2]. produced water includes a huge amount of oil hydrocarbons, salts, and dangerous matters, which is considered a toxic materials to environment. therefore, it is important to treat this water before disposal and either reuse it for irrigation, or reinject to the well. over the years, many researchers have been performed on the treatment of produced water that association within oilfields. cakmakci et al. [2] had investigated the pretreatment of produced water in the alternative reverse osmosis (ro) and nf membranes. the authors were found a suitable handling combination. in addition, microfiltration (mf) and uf were employed as a pretreatment of produced water, while ro and nf were utilized to decrease the salt content as a final treatment. with reference to the conventional separation methods that are usually utilized in the treatment of produced water, the uf seems to be one of the most successful method owing to its high efficiency of oil extraction, smaller space requirements, lower energy costs, and no bashir y. sherhan al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 1018 (2016) 11 necessity to use the other chemical additives during the treatment [3]. bilstad and espedal [4] reported the treatment of produced water of north sea oilfield by using ultrafiltration (uf) and microfiltration (mf) membranes. it was found that the hydrocarbon content decreased from 50 mg/l to 2 mg/l from and the removal efficiency of uf membrane was 96%. moreover, heavy metals, for instance, zn and cu were diminished by about 95%. furthermore, ro process and incorporated membrane pretreatment such as ultrafiltration (uf), and nanofiltration (nf) processes are nowadays seen to be the significate techniques for the treatment produced water application [5,6]. moreover, xu and co-authors [7] studied the treating of produced water created from sandstone aquifers by using nanofiltration (nf) and reverse osmosis (ro) membranes operated at very low transmembrane pressure. they are reported that the treated water can be used for irrigation and potable water. also, ashaghi et al. [8] used uf and nf ceramic membranes (membrane prepared from new materials) for the treatment of produced water. mondal and wickramasinghe [9] used two nf and one ro membrane for handling of various produced waters. they found that nf membrane was more applicable process for treatment of produced water according to the nature of the produced water and the water quality requirements. in this work, the application of either ultrafiltration (uf) or nanofiltration (nf) process was fundamentally studied in the treating of the raw produced water. a variety of hollow fiber membranes types were employed (i.e. pvc uf membrane, two different pes nf membranes, and ppsu nf membrane) in order to measure the turbidity, tds, cod, oil, no3, so4 and cl-1 removal efficiency of different membrane processes and focus on combined uf and nf techniques to enhance outflowing quality of the water. 2. experimental work 2.1 experimental system and procedure figure 1 shows a graphical diagram of the wastewater treatment system used in this study. the feed wastewater is pumped from the feed tank of uf via a diaphragm pump into the hollow fiber membrane module. the effective length of the hollow fiber module is 20 cm and the number of used hollow fiber is 8 with approximately 12 cm2 effective area. the feed temperature is fixed at 35ºc. the ultrafiltration membranes were prepared from poly vinyl chloride (pvc), whereas the nanofiltration membranes were prepared from polyether sulfone (pes) and poly phenyl sulfone (ppsu). fig. 1. schematic diagram of the raw produced water treatment system. the specifications of the ultrafiltration and nanofiltartion membranes are illustrated in table 1 and also demonstrated in figure 2. bashir y. sherhan al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 1018 (2016) 12 table 1, properties of the prepared uf and nf hollow fiber membranes. membrane code material and composition porosity mean pore size nm outer dia. mm inner dia. mm length of fiber cm uf pvc\dmac (16:84) 77% 120 1.2 1.0 30 nf1 pes/dmac (29:71) extrusion pressure is (1.5 bar) 56% 42.95 20 nf2 pes/dmac (29:71) extrusion pressure is (1.0 bar) 62% 53.52 20 nf3 (ppsu/nmp) (29:71) 49% 40.3 20 uf nf1 nf2 nf3 fig. 2. two dimensions afm images of the uf and nf membranes. bashir y. sherhan al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 1018 (2016) 13 the experiments were carried out in a batch circulation process where the concentrated solution is returned back to the feed tank, while the permeate stream is flowed to the permeate tank of uf process (feed tank for nf). ultrafiltration membrane (uf) is utilized mainly to the elimination of high molecular-weight substances, total suspended solids (tss), oil content, and either organic or inorganic polymeric molecules. this means that the hollow fiber (uf) membrane might be employed as a pre-treatment for hollow fiber nf membranes. besides, organics and ions that possess low molecular-weights like sodium, calcium, magnesium chloride, and sulfates as well as the heavy metals have been removed through the hollow fiber uf and nf membranes. the operating pressure of nf membranes is 6 bar and the trans-membrane pressures were determined from the difference between the pressures within the concentrate and permeate streams. accordingly, the solutions from the feed tank and the permeate flow were sampled for analysis. for each sample, both the removal efficiency (rejection) and the volume flux were measured at the steady state, which are established by approximately 30 min. the solute removal efficiency (rejection) (r%) was defined as follows: r(%) =[(cf− cp)/cf]×100 …. (1) where; cf and cp are the concentrations of the feed and the permeate flow, respectively. indeed, the concentration of both pb and cd ions within the feed stream and permeate streams were measured using atomic absorption (spectrometer), perkin elmer 5000. 2.2. analytical methods 2.2.1. determinations of cod and turbidity the chemical oxygen demand (cod) of the wastewater can usually be determined via spectrophotometer method with hach dr 2800 system and consistent with 5220 american public health association (apha) methods. likewise, the turbidity of the wastewater was carefully calculated by applying the turbidity meter (wtw turb 550, inolab). 2.2.2. determination of oil content (5520 apha) the quantity of associated oil with the wastewater was estimated next to the extraction from water due to intimate contact by means of an extracting solvent (ccl4). subsequent to the removal route in a soxhlet apparatus with solvent, the remaining residue from the evaporated solvent is weighed in order to discover both oil and grease content. in fact, the volatilized compounds around or less than 103°c seen to be misplaced as soon as the filter had been dehydrated. a 500 ml of permeate sample was stored in a conical flask, and then both (2.5-3.5) ml of hcl acid and 15 ml of ccl4 were correspondingly added. the mixture was agitated and followed by stirring, which is led to appear an oil layer in the bottom of the conical flask. the completed oil layer was simultaneously withdrawn out and kept inside a weighted flask. consequently, the flask is placed within a water bath for heating and after that dried out in an oven for 120 minutes at 360°c. the oil content was then calculated by applying the following equation: oeff www =+ ….(2) where fw is the weight of flask with oil layer, efw is weight of empty flask and ow is amount of oil content . 3. results and discussion it is well known that the wastewater needs to be pre-treated using ultrafiltration and/or microfiltration prior to the final treatment process by the use of nanofiltration (nf) or reverse osmosis (ro) units with the aim of removing every undesired components (i.e., suspended materials, emulsions, and colloidal materials), which have an influence on the performance of either nf or ro membrane. because of the increase in the requirements for pure water due to the continuous enlargement of population and the evolution of sustenance concept in addition to the insufficiency of water resources, the water reuse and/or solving these environmental and economical problems is thus becoming much more important. for that reasons, it is essential to make treatment to the wastewater within the specification limits according to the who earlier than discharging as explained in table 2. bashir y. sherhan al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 1018 (2016) 14 table 2, characteristics of raw produced water with who water quality standards. parameters units values who turbidity (ntu) 9.5 1-5 conductivity (µs/cm) 32600 500-2000 tds (mg/l) 15870 1200 ph 8.5 6.5-8.5 cod (mg/l) 383 200 toc (mg/l) 112 200 oil content (mg/l) 98.8 10 tss (mg/l) 126 0-200 mn (mg/l) 0.11 fe (mg/l) nil 0.3 zn (mg/l) 0.08 5 pb (mg/l) 0.04 0.01 ni (mg/l) 0.01 0.02 cr (mg/l) 0.02 0.05 cu (mg/l) 0.05 2 cd (mg/l) 0.01 0.003 cl(mg/l) 8900 200 so4 -2 (mg/l) 110 250 no3 (mg/l) 48.4 10-50 figure 3 shows the turbidity removal efficiency of produced water by using various membrane separation processes. it can be seen that the turbidity of the produced water is decreased from 9.5 to 0.48 nephelometric turbidity unit ntu by using pvc hollow fiber ultrafiltration membrane (i.e. 95% removal efficiency). whereas, further diminishing can be observed in turbidity of the produced water using nf1, nf2, and nf3 membranes (i.e. 0.25, 0.23 and 0.15, respectively). it seems during this study that the use of pvc hollow fiber uf membranes or nf membranes makes the turbidity of the produced water within the allowable limits of the who as presented in table 2. it is worth to mention here that the small quantity of water turbidity may be alleviated the appearance of fouling as a result of organic components within uf and nf membranes, which may accordingly be led to the enhancement of the membrane performance. fig. 3. turbidity removal efficiency of different membrane processes. conductivity of water is an indicator to presence of inorganic dissolved solids such as either the negative ions of chloride, sulfate, phosphate, and nitrate anions or the positive ions of sodium, calcium, magnesium, aluminum, and iron cations. the conductivity of raw produced water is about 32600 (µs/cm), whereas the conductivity value of the who water quality standards should be 500-2000 (µs/cm) as scheduled in table 2. therefore it can be stated that the use of uf with three different nf hollow fiber membranes would be able to decrease the conductivity of water, and a minimum value of 10000 (µs/cm) could be obtained by applying the nf3 as shown in figure 4. fig. 4. conductivity difference between various membrane processes. the total dissolved solid (tds) of the raw produced water is about 15870 (mg/l) and the standard magnitude value should be not exceed than 1200 (mg/l) as illustrated in table 2, since a bashir y. sherhan al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 1018 (2016) 15 high tds concentration means a high dissolved salts concentration. figure 5 establishes the tds removal efficiency of different hollow fiber membrane processes. it can be seen that the higher removal efficiency is 6090 (mg/l) using nf3 hollow fiber membrane. it is worth to mention here that all the revealed values of tds for the treated water are at concentrations upper than the acceptable irrigation or drinking water standards. fig. 5. tds removal efficiency by using different membrane processes. figure 6 confirms the cod removal efficiency of produced water by using different hollow fiber membrane processes. it can be noticed that the cod of the raw produced water is decreased from 383 to 160 (mg/l) using pvc hollow fiber uf membrane and this magnitude value is in fact less than the permissible restrictions set by who water quality standards as exemplified in table 2 and table 3. with the purpose of reduction the cod value within the treated water by utilized uf hollow fiber membrane, three different nf membranes have been employed and the obtained value of cod by nf3 seems to be attained approximately 122 (mg/l). fig. 6. cod removal efficiency of different membrane processes. one of the potential sources of environmental pollution is the oil content. this was observed when the analysis was accomplished on the raw produced water, since the value of oil concentration is reached to 98.8 (mg/l) as given in table 2. the results of analysis of a pre-filtration sample (i.e. permeate sample out from uf membrane) are detected that the oil concentration of produced water is within 26.8 (mg/l) as illustrated in table 3. whereas, the post-filtration concentration of oil by using three different nf membranes such as nf1, nf2 and nf3 are seen to be reduced to 1.4, 1.0 and 0.07, respectively as proved in figure 7. these magnitude values of oil concentration in permeate sample of nf membranes are lower than the permissible limits according to the who water quality standards as given in table 2. figure 8 shows the removal efficiency of cl-1, so4 -2 and no3 components of the produced water after treatment using different membrane separation processes. it can be noticed that the cl-1 component was decreased from 8900 mg/l within the raw produced water to 780, 690, and 646 mg/l subsequent to the use of nf1, nf2, and nf3 with achieved removal efficiencies of 21, 61, and 89%, respectively. these magnitude values of cl-1 concentrations inside the permeate stream of three different nf membranes are still higher than the allowable limits of who water quality standards as earlier mentioned in table 2. the sulfate ion (so4 -2) within the raw produced water seems to be 110 mg/l with removal efficiency of so4 -2 using uf membrane of about 27%. however, using nf membranes (i.e. nf1, nf2, and nf3) results to the reduction of so4 -2 ion within the permeate stream and hence increasing the removal efficiencies to become 46, 75, and 75% respectively. fig. 7. oil removal efficiency of different membrane processes. bashir y. sherhan al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 1018 (2016) 16 fig. 8. removal efficiency of no3, so4 and cl-1 of the treated produced water. accordingly, all the obtained analysis for so4 -2 within the post-treatment samples is seen to be complied with the licit limits specified by who water quality standards as confirmed in table 2. regarding to no3 removal efficiency, it can be observed in figure 8 that the no3 elimination efficiency by applying uf membrane is 20%, but three different nf membranes have surprisingly been shown much high levels of no3 removal efficiency (i.e. 98, 99, and 96 % for nf1, nf2, and nf3, respectively). in addition, the analyzed permeate samples for no3 components are within the range of acceptable limits of who water quality standards as provided in table 2. during the last few years, consideration had been concentrated on the exclusion of heavy metal ions from the wastewater attributable to its toxicity and consequently its effect on the human health. for that reason and consistent with the environmental policy it is imperative to get rid of the entire heavy metals from the wastewater in different industries with the intention that the wastewater necessitates total control earlier than liberation into the environment [10]. finally in table 2, it can be recognized that all of the obtained heavy metals results either by pre-filtration (i.e. uf membrane) or postfiltration (i.e. nf membranes) are in reality within in the range of the allowed limits placed by who water quality standards excluding the pb and cd components. it is well known that both pb and cd ions are the most dangerous heavy metals owing to their stability inside the tissue of the human body. hence, by using pvc hollow fiber uf membrane the removal efficiency of both pb and cd ions within the permeate stream is remained at 100% as offered in table 3 [10]. table 3, characteristics of produced water outflow from uf module. parameter uf turbidity (ntu) 0.48 conductivity (µs/cm) 30800 tds (mg/l) 17500 ph 8.4 cod (mg/l) 160 toc (mg/l) 5.1 oil content (mg/l) 26.8 tss (mg/l) 6 mn (mg/l) 0.09 fe (mg/l) nil zn (mg/l) 0.06 pb (mg/l) nil ni (mg/l) nil cd nil cr nil 4. conclusions new hollow fiber membranes of different separation processes were utilized for the treatment of raw produced water with the aim of reuse it in other processes. by using uf and three different types of nf membranes, turbidity, cod, oil content, tss, all heavy metals with the exception of neither pb & cd nor so4 -2 & no3 are perceived to be complied with the acceptable limits along with who water quality standards. the findings of this research detected that the permeate flow out from three hollow fiber nf membranes are still found to be elevated than the allowed restrictions of who water quality standards intended for conductivity, tds and cl-1. it can be concluded that these types of membranes can be utilized to the removal of all contaminants except for conductivity, tds and cl-1, thus it can be recommended to use such reverse osmosis membrane process to facilitate make the salinity of the treated water within the permissible limits of who water quality standards. acknowledgment chemical and petrochemical research center, corporation of research and industrial development, ministry of industry & minerals, baghdad, iraq support this study. bashir y. sherhan al-khwarizmi engineering journal, vol. 12, no. 3, p.p. 1018 (2016) 17 5. references [1] q. f. alsalhy, r. s. almukhtar, h. a. alani, treatment of oil refinery wastewater by membrane bioreactor (mbr), arabian j. of sci. and eng., published online 24 october 2015. 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[8] p. xu, j.e. drewes, d. heil, beneficial use of co-produced water through membrane treatment: technical-economic assessment, desalination 225 (2008) 139–155. [9] s. mondal, s. ranil wickramasinghe, produced water treatment by nanofiltration and reverse osmosis membranes, journal of membrane science, 322 (2008) 162–170 [10] b. al-rashdi, c. somerfield, n. hilal, heavy metals removal using adsorption and nanofiltration techniques, sep. purif. rev. 40 (2011) 209 – 259. �� ��ھ�ن ��� )2016( 1018، ! �� 3، ا���د����12 ا�� ارز�� ا������� ا����� 18 ����� ا���ء ا���% ,�%��ام أ(��� ا�%���$ ا� �)' وا�%���$ ا���# ي� �� ��ھ�ن ��� ***�67١ 34�5 �12 ا����� ** ١أر د�� �12س * ١ ٢ <�ى ���� ���ي ٢;���ة �89 �12س ? ٢# رة ��2ر �12 ا�@� ٢ا �ن ا� ��f de ٢زھ�اء و�2 هللا ر��د �٢ن ر��دآaء #�2 �� ا�����١� � �� ا������ ا� ����و�� / و��ة �� ث �� /�� � � � ا�!� �� ا� �$ ا�(��)'/ $#& ا�%� ث ا� ����و�� وا�%�$و #����و�� ٢*� ا��$اق/وزارة ا�(��)� وا����دن / ھ�,ة ا�%�+ وا� bashiryoush1974123@yahoo.com �$و3' ا�%$�� : ا�� * areej_dalf@yahoo.com **'3و$� :ا�%$�� ا�� qusay_alsalhy@yahoo.com �$و3' ا�%$��*** : ا�� �!gا�� �%$�� . =' ���!� ا���ء ا��(��@ �:�6? 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(received 17 march 2008; accepted 2 september 2008) abstract this paper demonstrates the design of an algorithm to represent the design stages of fixturing system that serve in increasing the flexibility and automation of fixturing system planning for uniform polyhedral part. this system requires building a manufacturing feature recognition algorithm to present or describe inputs such as (configuration of workpiece) and built database system to represents (production plan and fixturing system exiting) to this algorithm. also knowledge – base system was building or developed to find the best fixturing analysis (workpiece setup, constraints of workpiece and arrangement the contact on this workpiece) to workpiece. keywords: fixturing system planning, fixturing system analysis, computer aided fixturing system planning. introduction a key concern to a manufacturing company is the ability to manufacture high quality products in a short time as possible. quick release of a product into the market place, ahead of any competitors, is crucial to securing a higher percentage of the market place (1) . fixtures play an important role within many manufacturing processes such as machining, inspection and assembly (2) . they accurately locate and secure a workpiece during machining such that the part can be manufactured to design specifications. thus fixtures have a direct effect upon machining quality, productivity, and the cost of products (3, 4) . fixtures are used to locate and constrain a workpiece during a machining operation, minimizing workpiece and fixture tooling deflections due to clamping and cutting forces are critical to ensuring accuracy of the machining operation. traditionally, machining fixtures are designed and manufactured through trial-anderror, which prove to be both expensive and timeconsuming to the manufacturing process. the fixture design process can be divided into (5) : fixture planning is to determine the number of setups, the orientation of workpiece in each setup, the machining surface in each setup, and determine a set of locating and clamping points on workpiece surfaces such that the workpiece is completely restrained. fixture construction is to select fixture elements, and place them into a final configuration to locate and clamp the workpiece. fixture assembly is to assemble fixture components in strict accordance with the previously stage. to ensure a workpiece is manufactured according to specified dimensions and tolerances, it must be appropriately located and clamped, making it imperative to develop tools that will eliminate costly and time-consuming trial-anderror designs. proper workpiece location and fixture design are crucial to product quality in terms of precision, accuracy and finish of the machined part. theoretically, the 3-2-1 locating principle can satisfactorily locate all uniform polyhedra shaped workpiece. this method haidir raheem zghair al-khwarizmi engineering journal, vol. 4, no. 3, pp 43-56 (2008) 44 provides the maximum rigidity with the minimum number of fixture elements. to position a part from a kinematics point of view means constraining the six degrees of freedom of a free moving body (three translations and three rotations). three supports are positioned below the part to establish the location of the workpiece on its vertical axis. locators are placed on two peripheral edges and intended to establish the location of the workpiece on the x and y horizontal axes (5, 6, 7 & 8) . the goal of this paper is describe the stages of fixturing system planning for uniform polyhedra workpiece this stage begin from extraction and recognition manufacturing features from cad package and building database system for represent production plan and fixturing system exiting. secondly, built knowledge-base system for fixturing system plan to represent type of fixturing, number of fixturing need and positioning of fixturing. finally, determine fixturing system analysis is using same knowledge-base system that contain determined part setup or orientation and determine the faces and features to locate, support and clamp it, also determined the point contact on the faces or features and arrangement element according to this points. system architecture the system architecture of automatic fixturing system planning (a.f.s.p) is depicted in fig (1). manufacturing feature feature technology can, in general, be classified into feature extraction, feature-based design, and feature conversion. feature extraction (or feature recognition) is mainly concerned with identifying certain features from the various types of product representations such as boundary representations or solid models. feature-based design, by contrast, aims at building a product model with a predefined set of design features. feature conversion is the methodology that converts features defined in one domain to those of other domains (e.g., the conversion from design features to manufacturing features) (9) . the advantage of using features in engineering comes from the abstraction of information that the features provide. the features retain not only the geometric information but also much of the useful non-geometric information that is of interest in engineering applications. since there are many different application areas, the definitions of features vary widely. fig.1. the (afsp) system architecture. fixturing system planning knowledge – base system fixturing system analysis knowledge base fixturing system plan knowledge – base system determine the point contact on the faces or feature and arrangement element according to this point part setup or orientation and determine the faces and feature to locate, support and clamp it database representation production plan database fs exiting database cad manufacturing features recognition extraction entity from cad package by dxf haidir raheem zghair al-khwarizmi engineering journal, vol. 4, no. 3, pp 43-56 (2008) 45 feature is defined: -as special information about the semantics of part of the geometry and topology (10) . for process planning a feature is defined as a geometric form and a set of specification for which a process planning exists and this process is almost independent of the feature of the parts (9) . automatic feature recognition techniques provides the capabilities for translating the part definition data between cad & the feature needed to drive, for example, a process planning system. applied to process planning a part, feature recognition system would distinguish features of a part based on the geometric and topological information stored in the cad database. once a feature and associated manufacturing information are identified, the information then can be passed to process planning to generate process plans (11) . the afr technique is to take a general cad model, which is available commercially to provide an automated interface to recognize and extract the manufacturing features from the model. feature extractor will derive all the features of a part based on the geometric and topological information stored in cad database. feature recognition from solid model has been considered as one of the solutions for bridging cad & cam (9) . the afr technique is developed by geometric operation on b-rep solid models. it automatically identifies and groups topological entities, such as faces of a b-rep model, into functionally significant features such as holes, slots, pockets, ribs, fillets, etc. it also extracts their size and positional parameters for use later on (10) . process planning activities such as setup generation, process selection, tool selection, machining sequence, etc. are largely dependent on the types of features and their inter-relationships in the model. afr outputs feature information that is useful to various processes planning activities (9 , 10) . the proposed algorithm of features recognition supported by rules-condition facility, which is specific for processing the uniform polyhedral workpiece. this algorithm has the capability of recognizing the most prismatic features. generally, the algorithm is divided into many stages for recognition features represented in fig (4). first stage includes many tasks and starts from extraction of 3d data required stored in cad database, processing, converting, and preparing these entities data for next stage. the second stage includes also many tasks which begin from representing and defining of the geometric entities parts by faces, edges and vertexes classifying predefined features and extraction and recognition of the manufacturing features and determining all parameters associated with all developed features such as orientation and location. uniform polyhedra split to six faces (top, buttom, left, right, front, back) each two faces is opposite as show in fig (3). cad system autocad 2004 3d model dxf file read & determine data of 3d model user extract geometrical data of 3d model recognition of part features features data analysis determine orientation and location output data fig.2. algorithm for recognition features. haidir raheem zghair al-khwarizmi engineering journal, vol. 4, no. 3, pp 43-56 (2008) 46 uniform polyhedra workpiece divided into (12) edges used the distance between two edges in the same face to determine the location of machined (mf) and unmachined (features to be machined or required feature) feature (uf) as shown in fig (4). fixturing system planning the objective of fixturing planning is to determine number of setups needed, the position and orientation of workpiece in each setup and to determine the locating and clamping surfaces and points contact on the workpiece. fixturing planning consists of two main stages (6) : 1fixturing system plan knowledge–base (fspkb) this stage contain specification type, number and position of fixturing system depend on the type of operation required produced, number of piece to be made or batch size and number of unmachined feature (uf) and location of this feature on the workpiece. fig (5) shows this stage. top face left face right face back face front face buttom face fig.3. determine number and name of faces on the uniform polyhedra workpiece. fig.4. relational location of machined feature for uniform polyhedra workpiece. top face left face right face back face front face buttom face e1 e5 e7 e6 e8 e4 e2 e3 e12 e11 e10 e9 e1 e4 e2 e3 edges exiting on the top face e5 e7 e6 e8 edges exiting on the buttom face e10 e9 edges exiting on the left face e12 e11 edges exiting on the right face haidir raheem zghair al-khwarizmi engineering journal, vol. 4, no. 3, pp 43-56 (2008) 47 start inter type of operation required produced select type of fixturing appropriate to the type of operation type of fixturing inter number of piece to be made or batch size no. of piece = mass production yes no number of fixturing needed used one fixturing system used more than one fixturing system positioning of fixturing inter number of unmachined feature no. of unmachined feature = 1 yes no inter location of unmachined feature used fixed fixturing location = on the same face end end no yes used sliding, rotary and indexing fixturing specified the unmachined feature exiting on the same face to use fixturing appropriated fig. 5. algorithm for fixturing plan. haidir raheem zghair al-khwarizmi engineering journal, vol. 4, no. 3, pp 43-56 (2008) 48 examples of rules used for finding type, number and positioning of fixturing system shown in table (1). table 1 example of rules used for fixturing plan 2fixturing system analysis knowledge base (fsakb): this stage can be classified into two main parts: 2-1 workpiece setup (machining references, locating and clamping face): determine workpiece setup one of the important task to success fixturing design due to stability and securing of the workpieces under certain force application and limit kinematics freedom. for each setup, must ensuring the fixturing configuration will provide a force closure on the workpiece and enable reach to feature to be machined without interfere with tool path. generally, determine the workpiece setup depend on representation or description the details geometric workpiece and using rulebased system to processing this details to get on the best and minimum number of workpiece setup. in this paper, used one setup operation after specify number of unmachined feature (uf) and location of this feature. if the location of this feature exiting on the one face used one setup operation. but, if location of this feature exiting on the more than one face will select large number positioning of fixturing system [(rule 1: (if (number-of-required feature = one)) (then (positioning-of-fixturing-system = fixed fixturing system))) (rule2: (if (number-of-required feature = more than one) and (location-of-required-feature = on the same face)) (then (positioning-of-fixturing-system = sliding, rotary and indexing fixturing system))) (rule3: (if (number-of-required feature = more than one) and (location-of-required-feature = on the different face)) (then (positioning-of-fixturing-system = cannot find positioning)))] type of fixturing system [(rule 1: (if (type-ofoperation = drilling)) (then (type-of-fixturing-system = drilling jig))) (rule2: (if (type-of-operation = milling)) (then (type-of-fixturing-system = milling fixture)))] number of fixturing system [(rule 1: (if (number-of-piece-to-be-made = mass production) or (batch-size = mass production)) (then (numberof-fixturing-system = more than one)))] haidir raheem zghair al-khwarizmi engineering journal, vol. 4, no. 3, pp 43-56 (2008) 49 of this feature exiting on the one face to get on one setup operation. also, after specified the number of setup required. the machining references, first and second locating face and clamping face are determined. in uniform polyhedra workpiece, the machining references represent the opposite face to the clamping face that unmachined feature (uf) exiting it and determine first and second locating face that ensuring full constraint to the prismatic workpiece. example, if the unmachined feature (uf) exiting on the top face, top face represent as clamping face, buttom face as machining references, right face as first locating face and back face as second locating face as shown in fig (6). 2-2 determine contact on the faces selected: after pinpointing the faces that locating and clamping it, contact important to get on the best equilibrium to the workpiece must be determined. this part begins firstly, in definition the machined feature (mf) exiting on the faces selected. secondly, specify the number and type of clamping contact on the clamping face. in uniform polyhedra workpiece, using point contact and face contact according to type of feature or operation machining required. if the unmachined feature is hole, used face contact to easy use drill bushing and prevent the movement resulted from the drilling moment and formatted according to the machined feature (mf) exiting on the clamping face. but, if the unmachined feature is slot or other type used point contact specified depend on the location of machined and unmachined feature exiting on the clamping face with ensuring not interfere with tool and feature and definition this point according to the method using in determine the feature for uniform polyhedra workpiece presented previously. thirdly, select the locating and supporting point contact on machining references. in uniform polyhedra workpiece, use three-point contact on the machining references. if hole feature is founded or selected, one locating point contact and two supporting contact is used. but, hole feature is no selected, three supporting point contact is used. fourthly, select the locating and supporting contact on the first, second locating and support faces. in uniform polyhedra workpiece, use two locating or supporting point contact in first locating face and use one support point contact on the second locating face. uniform polyhedra workpiece arrangement the point contact on the face used in locating and supporting depend on the design consideration to this element. fig (7) illustrated the step of the procedure used in the fixturing analysis. location of unmachined feature = clamping face first locating face = right face machining references = buttom face second locating face = back face fig.6. the rule used in constraint uniform polyhedra workpiece. top face haidir raheem zghair al-khwarizmi engineering journal, vol. 4, no. 3, pp 43-56 (2008) 50 fig. (8) shows examples of rules used for determining number of setup operation, rules used for determining the faces used locating, supporting and clamping, and some of rules used in this step. inter overall shape contacts on the faces selected yes two setup operation start inter location of uf1 and uf2 no inter number of unmachined feature one setup operation no. of uf = 1 yes no. of feature = 2 no continuous until number of unmachined feature is complete number of setup required no location of uf1 & uf2 on same face yes one setup operation select one of this two feature to determine one setup operation required select machining references, first, second locating and clamping face determination the number and type of contact on this face arrangement this points on the faces selected and determine the location to these points end fig.7. flowchart for fixturing analysis. note: uf1 = unmachined feature 1 uf2 = unmachined feature 2 uf = required feature haidir raheem zghair al-khwarizmi engineering journal, vol. 4, no. 3, pp 43-56 (2008) 51 number of setup operation [(rule 1: (if (number-of-required feature = one)) (then (positioning-of-setup-operation = one setup operation))) (rule2: (if (number-of-required feature = more than one) and (location-of-required-feature = on the same face)) (then (positioning-of-fixturing-system = one setup operation))) (rule3: (if (number-of-required-feature = more than one) and (location-of-required-feature = on the different face)) (then (positioning-of-fixturing-system = more than one setup operation)))] find the faces for locating, supporting and clamping it [(rule 1: (if (overall-shape = uniform polyhedra) and (location-of-required-feature = on the top or buttom face)) (then (face-selected = machining references, first and second locating face and clamping face))) (rule2: (if (location-of-required-feature = on the top face)) (then (machining-reference = on the buttom face) (locating-face = on the right and back faces) (clamping-face = on the top face))) (rule3: (if (location-of-required-feature = on the front face)) (then (machining-reference = on the back face) (locating-face = on the left or right face and on the top or buttom face) (clamping-face = on the front face)))] fig. 8. example of rules used for fixturing planning. number and type of contact on clamping face [(rule1: (if (number-of-machined-feature = non) and (number-of-unmachined-feature = existing) or (type-of-unmachined-feature = hole)) (then (number-of-contact = one) (type-of-contact = from face) (arrangement-contact = on the overall size of face)))] number and type of contact on machining references [(rule1: (if (number-of-machined-feature = non)) (then (number-of-contact = three) (type-of-contact = from point) (arrangement-contact = near to the center of workpiece)))] haidir raheem zghair al-khwarizmi engineering journal, vol. 4, no. 3, pp 43-56 (2008) 52 the full description to the practical application and other input to the automatic fixturing system planning (afsp) system show in fig (9) and table (2). fig. 8. examples of rules used for determining fixturing planning. number and type of contact on first and second locating face [(rule1: (if (number-of-machined-feature = non) and (number-of-machined-feature = one) or (number-of-machined-feature = more than one)) (then (number-of-contact = one) (type-of-contact = from face) (arrangement-contact = on the overall size of face))) (rule2: (if (type-of-machined-feature = hole)) (then (number-of-contact1 = one) (number-of-contact2 = one) (type-of-contact1 = from hole) (type-of-contact2 = from face) (arrangement-contact1 = same location of hole) (arrangement-contact2 = overall size of face)))] fig. 9. drawing of practical application. unmachined features machined features top face = clamping face buttom face = machining references left face = first locating face back face = second locating face e1 e5 e7 e6 e8 e4 e2 e3 e12 e11 e10 e9 haidir raheem zghair al-khwarizmi engineering journal, vol. 4, no. 3, pp 43-56 (2008) 53 table 2 practical application configuration. no. of m.f. list of m.f. location of machined feature (m.f). length depth width diameter other position 1 hole on the bottom face 18.8 2.5 (20 and 8)mm between hole center and (e7, e6) no. of r.f. list of r.f. location of required features (rf) length depth width diameter other position 2 hole on the top face 1.6 6.25 (15 and 8) mm between hole center and (e3, e1) hole on the top face 1.6 6.25 (23 and 8) mm between hole center and (e3, e1) the windows that representing the automating algorithms of fixturing system planning shown in figs. (10, 11, 12, 13, 14 and 15). fig.10. main window for system. fig.11. workpiece properties window database. the system in this stage through interaction with the user performs extraction and recognition tasks of the manufacturing features from processing the geometric entities data and converts it from low level into high level representation called features. the window illustrate in figure (12) represents a link between cad and system through automated information design by extraction and recognition of the manufacturing features. the feature recognition window consists of main procedures related of part analysis, which contain all data required for the next steps. fig.12. workpiece configuration window database. fig.13. fixturing system exiting window database. haidir raheem zghair al-khwarizmi engineering journal, vol. 4, no. 3, pp 43-56 (2008) 54 fig.14. fixturing planning window. fig.15. fixturing system analysis (contact analysis) window. conclusion in manufacturing, tooling includes selection, design, and fabrication of cutter tool, fixturing system, inspection devices and molds. fixturing system is an important aspect of manufacturing process and has become one of the bottlenecks in implementation of cim (computer integrated manufacturing). the cost of designing and fabricating fixturing system can amount to (10% 20%) of the total manufacturing system cost, also the time and effort spanned by designer to design fixturing system is very important therefore, it is important use the computers and ai (artificial intelligence) techniques to increase the efficiency of design fixturing systems. this system applied to various types of uniform polyhedra work pieces (various sizes and types) and use database system leads to simplifying the ability of the user to enter, change and expand data, also the ease of searching between these data to find the data required and reduces the time and effort required to describe the workpiece. applying knowledge– based (rule-based) system to fixturing system analysis has proved a powerful tool and very useful to get the efficient results for the number of workpiece setup and finds faces or feature for clamping, locating and supporting it also arrangement contact on this faces that realization best equilibrium to the workpiece. the workpiece selected in this research is one of some of workpiece are used to test system that getting from some of papers related to this research. the fixturing plan results show below: type of fixturing system drilling jig number of fixturing system one number of part faces 6 number of setup operation one setup operation buttom face using as machining references contain hole feature as machined feature. position of this feature is determined between the edge (e7 and e6). right face present first locating face and back face as second locating face and determined the dimension for this face. the clamping face using as clamping face. the result for fixturing system analysis also shows below: contact analysis on number of contact type of contact clamping face 1 from face machining references 2 1 from point from hole first locating face 2 from point supporting or second locating face 1 from face the position and the dimension fro this contact is determined. by studying results of the previous application the following points, can be noticed: 1depending on the location of required feature to specify number of workpiece setups helps the user to get on the minimum of setup operations and also the use of location of these features leads to best decision for fixturing system position. 2finding the faces for locating, clamping, and supporting depends on the rules constraint of rotational workpiece that results in getting the haidir raheem zghair al-khwarizmi engineering journal, vol. 4, no. 3, pp 43-56 (2008) 55 best equilibrium and constraint to this application. 3using faces to support or locate this application instead of using a point, gives lager stability to application and removes the complexity because the large number of machined features exist on the faces of application. 4basically using screw force for clamping element reduces time, effort and wear of these elements, it also gives maximum clamping force for rotational applications. 5use locating and supporting element such as (locating rest pad) lead to minimum number of elements selected. references [1] iain m. boyle, kevin rong and david c. brown; “cafixd: a case-based reasoning fixture design method. framework and indexing mechanism”; computer and information in engineering conference; september 28 – october 2, 2004, salt lake city, utah usa. 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"features recognition for process planning" manufacturing engineering laboratory, the national institute of standards and technology, united states department of commerce, 2000. haidir raheem zghair al-khwarizmi engineering journal, vol. 4, no. 3, pp 43-56 (2008) 56 تصميم خوارزميه التمته تخطيط انظمه التثبيت لقطعه العمل المتعذدة السطوح المتناسقه ** امجذ برزان** زيذ حكمت يعقوب*ر رحيم زغيرحيذ جاٍؼت بغذاد/ مييت ىنذست اىخٌارسٍي/ قسٌ ىنذست ػَيياث اىخصنيغ* اىجاٍؼت اىخننٌىٌجيت / قسٌ ىنذست االنخاج ًاىَؼادُ** ة الخالص ىذا اىبحث يقذً حصَيٌ خٌارسٍيو ىخَثيو ٍزاحو حصَيٌ انظَو اىخثبيج ً اىخي حساىٌ في سيادة ٍزًنو ً احَخو حخطيط انظَو اىخثبيج ً مذىل بناء قاػذه (شنو قطؼو اىؼَو)ـىذا اىنظاً يخطيب بناء خٌارسٍيو ىخٌىيذ اىسَاث اىخصنيؼيو ك. ىالشناه اىَخؼذدة اىسطٌح اىَخناسقو مذىل بناء قاػذة اىَؼزفو اليجاد افضو ححييو . (خطو االنخاج ً انٌاع انظَو اىخثبيج اىٌَجٌدة)اىبياناث ىٌصف اىَذخالث ىيذا اىنظاً ٍثو . ىقطؼو اىؼَو (نصب ً حقييذ قطؼو اىؼَو ً حزحيب اىخالٍس ػيى قطؼو اىؼَو)ىيخثبيج 98 al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 4, no. 3, pp 98-107 (2008) heating and melting model induced by laser beam in solid material faiz f. mustafa department of manufacturing operations engineering /al-khwarizmi college of engineering university of baghdad (received 2 march 2008; accepted 15 june 2008) abstract an analytical method and a two-dimensional finite element model for treating the problem of laser heating and melting has been applied to aluminum 2519t87and stainless steel 304. the time needed to melt and vaporize and the effects of laser power density on the melt depth for two metals are also obtained. in addition, the depth profile and time evolution of the temperature before melting and after melting are given, in which a discontinuity in the temperature gradient is obviously observed due to the latent heat of fusion and the increment in thermal conductivity in solid phase. the analytical results that induced by m6.10 laser irradiation is in good agreement with numerical results. keywords: laser; heating; melting; finite element method; non-linear heat transfer 1. introduction high power density, such as laser beam, has been increasingly utilized in industrial manufacturing. the process of laser beam in solid material offers a great potential for the new product design, for example, welding, cutting of metals, drilling of holes, laser shock hardening and laser glazing. when a high power laser irradiates a material surface, a part of the laser energy is absorbed and conducted into the interior of the material. if the absorbed energy is high enough, the material surface will melt and even vaporize. the study of laser induced heating and melting has attracted great interest [1–7] and the results obtained are of great importance for achieving high quality materials processing with lasers. to simplify the mathematical problem, it is necessary to assume that the process of laser heating and melting is a linear process, that is to say, the physical parameters of the material, including density, thermal conductivity, thermal capacity, optical absorptivity, etc., are independent of the temperature. in this study, a one-dimensional heat conduction problem is solved approximately in the solid and liquid regions by assuming that the thermo-physical properties of the material are independent of the temperature. numerical simulation of laser heating and melting with two dimensional finite element methods has been used to evaluate temperature distribution and other variables. a nonlinear transient thermal analysis was performed using temperature dependent material properties used to evaluate temperature distribution the computations of the depth profile and time evolution of the temperature before melting as well as after melting are carried out for the two materials, the variation of the melt depth with time, the effects of the laser power density on the melt depth and the irradiation time on melting and vaporization are calculated. 2. mathematical model the geometry of laser irradiation and the resulting liquid and solid regions are shown in fig. 1. the diameter of the laser beam is broad enough compared to the molten region and the thickness of the material is much greater than the faiz f. mustafa al-khwarizmi engineering journal, vol. 4, no. 3, pp 98-107 (2008) 99 thermal penetration depth, so that the problem can be solved in one dimension and a semi-infinite model may be accepted. the analytical solution applied to aluminum and stainless steel, the thermo-physical parameters in solid and liquid phases are shown in table 1 were taken from [8-9]. accordingly the surface of the material reaches the fusion point or not, the whole process of laser induced heating and melting in the material is divided into two steps: before melting and after melting. fig. 1. the geometry of laser irradiation. table 1 thermophysical parameters and absorptivity for materials [8-9]. _______________________________________ material aluminum stainless-steel properties (2519t87) (304) ______________________________________ )/( 3mkgs 2823 7860 )/( 3mkgl 2485 6980 )/( kgkjcs 896 465 )/( kgkjcl 1080 691 )/( mkwk s 100 53 )/( mkwkl 238 120 )(ktm 933 1811 )(ktv 2793 3134 )10( 15 kgl 3.88 3.65 sa 0.0588 0.386 la 0.064 0.346 ______________________________________ 2.1. step a. before melting the thermal conduction model can be described by the following equations before the temperature of the surface reaches the fusion point: ,0 ),(1),( 2 2       t tyt y tyt s s s  ,0  y …(1) , ),( ia y tyt k s s s     ,0y …(2) ,),( ttyts  ,y …(3) ,),( ttyts  ,0t …(4) where sss kt ,, and sa are the temperature, thermal conductivity, thermal diffusivity and absorptivity of the solid phase respectively. t is the ambient temperature and i is the power density of laser beam. we first assume a temperature profile, which satisfies the boundary condition (3): ,)(),( )(/ ty ws etttyt  …(5) where )(ttw represents the temperature of the surface and )(t is a temporal function representing the temperature penetration depth in the solid. substituting expression (5) into eqs. (2) and (1), we get the following relations: ),( )( )( 2 tt tdt tdt w sw    …(6) ),()( t k ia tt s s w  …(7) according to eqs. (6) and (7), one gets ,)2()( 2 1 t kc ia ttt sss s w    …(8) .2)( tt s  …(9) 2.2 step b. after melting the thermal conduction equations in liquid and solid regions can be described as ,0 ),(1),( 2 2       t tyt y tyt l l l  ),(0 tsy  …(10) ,0 ),(1),( 2 2       t tyt y tyt s s s   yts )( …(11) with boundary conditions , ),( ia y tyt k l l l     ,0y …(12) faiz f. mustafa al-khwarizmi engineering journal, vol. 4, no. 3, pp 98-107 (2008) 100 ,),(),( mls ttyttyt  ),(tsy  …(13) , ),(),()( y tyt k y tyt k dt tds l l l s ss       …(14) ,),( ttyts  y …(15) and initial condition ,0)( ts ,mtt  … (16) where ii kt , and iiii ck  / are temperature, thermal conductivity and thermal diffusivity of the i th phase respectively ( si  (solid phase) or l (liquid phase)), i and ic are the density and heat capacity of the i th phase. la is the absorptivity of liquid phase, mt is the melting point and l is the fusion latent heat of the irradiated material, )(ts is the position of the interface between solid phase and liquid phase. the temperature profiles in liquid region and solid region are assumed as )(/ )(),( ty ml letttyt   …(17) )(/)( ),( ttsy ms settyt   … (18) which satisfy eqs. (13) and (15), )(tl and )(ts are two temporal functions representing the temperature penetration depth in liquid and solid regions. satisfying eq. (10) at 0y by using expression (17) and eq. (11) at )(tsy  by using expression (13), we obtain ,0 )( )()( 2  t tt dt tdt l wlw   …(19) . )( )( tdt tds s s    …(20) substituting expression (17) into eq. (12), we get . )( )( ia t ttk l l wl   …(21) substituting expressions (17) and (18) into eq. (14) and by using eq. (13), we obtain ). )()( ( )( )( t k t k l t td tds s s l l s m   …(22) according to eqs. (19)–(22), the following relations are obtained: )(ttw , 2 2/1 2 22        ct k ia l ll …(23) , 2 )( 2/1 2 22        ct k ia ia k t l ll l l l   …(24) , 2 )()( 2/1 2 22        ct k ia l kt ita l t l llsm s ml s s      …(25)   , /2 ln 2 )( 2/1222 2/1 2 22 m lll l ll l l t cktia ct k ia ia k ts            where .)( 2 22 22 2  tt ak ak tc m sls lsl m    3. finite element modeling during the laser irradiation many mechanisms are taking place in the basin material; a very narrow zone under the laser beam is suddenly heated, vaporized and locally fused. a twodimensional finite element model was used to simulate the laser processes on the depth of the solid material using the commercial code ansys (9). the geometry of the structure, shown in fig 2-a, was modeled using a two dimensional solid 8-nod element to simulate the laser processes on the depth of the solid material. the width of the material is broad enough compared to the molten region and the depth of the material is much greater to than the thermal penetration depth. the accuracy of the fe method depends upon the density of the mesh used in the analysis. the laser spot temperature is higher than the melting point of the material, and it drops sharply in regions away from the laser spot. therefore in order to obtain the correct temperature field in the region of high temperature gradients it was necessary to have a more refined mesh close to the laser spot, while in regions located away a more coarse mesh was used as shown in fig. 2-b. the final mesh was the result of compromise between computing time and accuracy. a transient heat transfer analysis was performed with an appropriate time-stepping scheme to achieve fast convergence of the solution and reasonable accuracy. the thermal analysis was conducted using temperature dependent thermal material properties the values of these properties for aluminum 2519 t87and stainless steel 304 are shown in table 2 were taken from [10-11]. the governing partial differential equation for the transient heat conduction is                                t t tctq y t x t tk p )()()( 2 2 2 2  …(27) where yx, are the cartesian coordinates, q the internal heat generation,  the density, k the thermal conductivity and pc the specific heat are function of temperaturet . the temperature dependent material properties were inserted in fe code in the table form. …(26) faiz f. mustafa al-khwarizmi engineering journal, vol. 4, no. 3, pp 98-107 (2008) 101 (a) (b) fig. 2. (a) 2-d solid 8-nod element. (b) 2-d finite element geometry and mesh. 3.1 heat input the heat input is generally calculated from the energy supplied, during laser irradiates at the solid material. the geometry considered in this dissertation is a finite, rectangular work-piece irradiated by a laser beam impinging on its surface and subjected to convection and radiation heat losses. a laser power p is assumed to have a uniformly distributed over a circular area of radius ω on the surface of a work-piece, so that a laser beam is assumed to have a uniform intensity distribution i defined as 2/pi  …(28) 3.2 boundary and initial conditions during the laser irradiates, the heat was supplied to the specimen surface by the beam laser. this heat is transferred to the metal by the conduction and convection. a part of this heat energy is lost by free convection and radiation. the heat loss by free convection follows newton’s law, where the coefficient of convective heat transfer was assumed to vary with both temperature and orientation of boundary. )( tt l knu qc  …(29) where k is the thermal conductivity of the material, l the characteristic length of the plate (or surface), t the ambient temperature, and nu nusselt number defined by 3/13/1pr67.5 grnu  …(30) where pr is the prandtl number and gr is the grashof number, both of them being functions of ambient air properties and temperature differences between the surface and the environment. heat loss due to thermal radiation between the spacemen and environment are important when the temperature difference is high. this radiation was modeled by the standard stefan-boltzman relation )( 44 ttqr   …(31) where  is the heat emissivity and  the stefanboltzman constant. radiation is assumed from the surface to the surroundings. the material is assumed to be at room temperature. 4. results and discussions we apply the above analytical solutions to aluminum and stainless steel. table 2 shows their thermophysical parameters in solid and liquid phases and their absorptivity at wave length m6.10 laser irradiation. faiz f. mustafa al-khwarizmi engineering journal, vol. 4, no. 3, pp 98-107 (2008) 102 table 2 variation of thermal properties with temperature [10-11]. _________________________________________________________ temp k (w/m/c) cp (j/kg/c)  (kg/m3) (°c) thermal conductivity specific heat density s.s al s.s al s.s al ________________________________________________________ 0 53 100 465 896 7860 2823 100 52 140 485 915 7721 2754 200 50 160 494 950 7648 2705 300 46 155 509 952 7603 2654 400 42 145 529 1080 7670 2613 500 39 145 562 = 7635 2559 600 36 180 582 = 7405 2500 700 32 238 638 = 7365 2485 800 25 238 691 = 7330 2485 900 27 690 7303 1000 28 688 7272 1100 29 = 7235 1200 30 = 7210 1300 31 = 7170 1400 32 = 7131 1500 70 = 7103 1600 120 = 7042 1700 120 = 6980 ________________________________________________________ 4.1. melt depth the propagation of the solid–liquid interface expressed by eq. (26) shows that the melt depth increases rapidly at the beginning of laser irradiation and then slowly after a certain time. such a trend is also observed in experimental studies for the laser drilling of aluminum [12]. the mathematical and finite element calculated melt depth evolution of aluminum induced by m6.10 laser irradiation compared to the experimental data [12] is shown in fig. 3. this figure shows a good agreement between the theory and the experiment for irradiation times less than about 4sec, but some deviations appear as the time increases. in fact, vapor and plasma will occur at large irradiation times; which block the incident laser light and absorb a portion of laser energy, but such effects are ignored in this work. as a result, the theoretical results seem to overestimate the melt depth for large irradiation times. therefore, the model expressed by eq. (26) is accurate when the vapor or plasma is not very strong, which is usually the case at the beginning of the irradiation process. the mathematical and finite element variations of melt depth with m6.10 laser irradiation time for aluminum and stainless steel are shown in fig. 4. at the beginning, the melting velocity is high and then decreases to a low value. the trend is the same as that observed in experimental studies. some deviations appear between mathematical and finite element especially at the time increases because the temperature independences thermal material properties of the mathematical model. 0 0.005 0.01 0.015 0.02 0.025 0 1 2 3 4 5 6 7 8 9 10 time (sec) m e lt d e p th ( m ) mathematical finite element experimantal fig. 3. melt depth evaluation of aluminum. faiz f. mustafa al-khwarizmi engineering journal, vol. 4, no. 3, pp 98-107 (2008) 103 0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0 1 2 3 4 5 6 7 8 9 10 time (sec) m e lt d e p th ( m ) s.s-mathematical s.s-finite element al-mathematical al-finite element fig. 4. melt depth evaluation of stainless-steel and aluminum i= 10 8 w/m 2 . 4.2. temperature profile and evolution the mathematical and finite element temperature fields as the functions of depth for aluminum at different irradiation times are plotted in fig. 5. (a) and (b). the curves 1 and 2 represent the temperature distribution in the solid before melting, while the curves 3 and 4 represent that after melting. for both models the temperature within the liquid phase decreases rapidly from the surface temperature to the melting temperature. beyond the solid–liquid interface in the solid phase region, the temperature decreases to the ambient temperature with a relatively gradual gradient. such a discontinuity in the temperature gradient is obviously observed due to the latent heat of fusion and the increment in thermal conductivity in the solid phase. it is also seen from the figure that the evolution of the surface temperature after melting is much faster than before melting, which results from the higher absorptivity and lower thermal conductivity in liquid phase. fig. 6. (a) and (b), gives the finite element temperature profile for aluminum and stainless steel at the same power density i= 10 8 w/m 2 for different time irradiate, we can see with the different time the melt depth of aluminum are less than that of stainless steel due to high thermal conductivity and low absorptivity. 0 200 400 600 800 1000 1200 1400 1600 1800 0 1 2 3 4 5 6 7 8 9 10 distance (mm) t e m p e ra tu re ( k ) 1 2 3 4 t=tm 0 200 400 600 800 1000 1200 1400 1600 0 1 2 3 4 5 6 7 8 9 10 distance (mm) t e m p e ra tu re ( k ) 1 2 3 4 t=tm fig. 5. temperature distribution of aluminum at different irradiation time i= 7*10 8 w/m 2 . (a) mathematical, (b) finite element. 4.3. the effects of power density on melt depth the variations of melt depth versus incident power density for a given laser irradiation time for aluminum and stainless steel are plotted in fig. 7. in the two cases (mathematical and finite element), the melt depth increases rapidly with increasing power density when the power density is low, and increases slowly at higher power densities. it is shown that the melt depths of aluminum are less than that of stainless steel at low power density, while greater than that at higher power densities. aluminum has high thermal conductivity and low absorptivity, so that they are difficult to melt compared to stainless steel at low laser power density. with the increment of incident power density, more laser energy can be conducted to the solid–liquid interfaces of aluminum due to their higher thermal conductivity so that more laser energy needs to be used to achieve melting. therefore, the melt depths of aluminum will exceed these of stainless steel at higher power density. (a) (b) faiz f. mustafa al-khwarizmi engineering journal, vol. 4, no. 3, pp 98-107 (2008) 104 (a) (b) fig. 6. temperature distribution during laser irradiation at different times, i=10 8 w/m 2 . (a) aluminum, (b) stainless steel. t=2 sec t=4 sec t=6 sec t=8 sec faiz f. mustafa al-khwarizmi engineering journal, vol. 4, no. 3, pp 98-107 (2008) 105 0 20 40 60 80 100 120 140 1.00e+08 1.00e+09 1.00e+10 i (w/m^2) m e lt d e p th ( m m ) s.s-mathematical s.s-finite element al-mathematical al-finite element fig. 7. influence of power density on melt depth at time= 5 sec. 4.4. the time for surface to melt and vaporization let )(ttw in eq. (8) equal the fusion temperature mt . the time for the surface reaching the melting point mt is 2 2 )(2 )( ia kctt t s sssm m   …(32) let )(ttw in eq. (23) equal the vaporization temperature vt .the time for the surface reaching the vaporization point vt is ll lv v ia kct t 2 22 )(2 )(   …(33) the results of two metals are shown in table 3. it is shown that stainless-steel needs least time to reach fusion temperature and vaporization temperature then aluminum due to its low thermal conductivity although it has relatively high fusion and vaporization temperatures. table 3 the time needed to melt and vaporize for materials at different power densities. ________________________________________________________ )/( 2mwi 108 109 1010 ________________________________________________________ melting al 1.175 1.175*10^-2 1.170*10^-4 time(s) s.s 0.148 0.148*10^-2 0.148*10^-4 vaporizing al 55.51 55.51*10^-2 56.01*10^-4 time(s) s.s 1.730 1.730*10^-2 1.730*10^-4 _______________________________________________________ 5. conclusions an analytical method for treating the problem of the laser heating and melting is considered in this paper by suggesting a simple and reasonable temperature profile and compared with a two dimensional finite element model. we apply the two methods to aluminum 2519t87 and stainless steel 403. the temperature profile and evolution of aluminum before melting as well as after melting is described. a discontinuity in the temperature gradient is obviously observed due to the latent heat of fusion and the increment in thermal conductivity in solid phase. the calculated melt depth evolution of aluminum is in good agreement with the experimental results. the effects of laser power density on the melt depths for two metals are also obtained. it can also be concluded that stainless steel needs least time to reach fusion temperature and vaporization temperature than aluminum due to its low thermal conductivity although it has relatively high fusion and vaporization temperatures. references [1] el-adawi mk, el-shehawey ef. heating a slab induced by a time-dependent laser irradiation—an exact solution. j. appl phys 1986; 60 (7): 2250–5. 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[6] v. a. karkhin, v. a. lopota, and n. o. palova. effect of phase transformations on residual stresses in laser welding. welding international 2003 17 (8) 645–649 [7] han guoming, zhao jian, li jianqang. dynamic simulation of the temperature field of stainless steel laser welding. school of material science and engineering, tianjin university, china, 8 june 2005. [8] s.a. tsirkas, p. papanikos, th. kermanidis. numerical simulation of the laser welding process in butt-joint specimens. j materials processing technology 2003; 134:59-69. [9] justin d. francis. welding simulations of aluminum alloy joints by finite element analysis. master of science in aerospace engineering april 2002 blacksburg, virginia [10] a. anca, a. cardona, and j.m. risso. 3dthermo-mecanical simulation of welding processes. centro internacional de m´etodos computacionales en ingenier´ıa (cimec), bariloche, argentina, november 2004. [11] d. berglund, l.e. lindgren and a. lundbäck. three-dimensional finite element simulation of laser welded stainless steel plate. computer aided design, luleå university of technology, 97187 luleå, sweden, 2004. [12] armon e, zvirin y, laufer g. metal drilling with a co2 laser beam. ii. experiment. j. appl. phys. 1989; 65 (12): 5003–8. faiz f. mustafa al-khwarizmi engineering journal, vol. 4, no. 3, pp 98-107 (2008) 107 النمىذج الحراري واالنصهاري الناتج من الحسمة الليسرية على المىاد الصلبة فائس فىزي مصطفى ظايعح تغذاد/ كهٛح ُْذسح انخٕاسصيٙ/ قسى ُْذسح عًهٛاخ انرصُٛع الخالصة ذى اسرخذاو ًَٕرض , نٕصف ظاْشج اسذفاع انحشاسج ٔانٕصٕل انٗ دسظح االَصٓاس انُاذط يٍ حضيح نٛضسٚح يسهطح عهٗ ظسى صهة ٔانحذٚذ انًقأو (2519t87) سٚاضٙ احاد٘ انثعذ تاالضافّ انٗ اسرخذاو طشٚقح انعُاصش انًحذدِ شُائٛح انثعذ نكم يٍ يادج االنًُٕٛو َٕع دسظح االَصٓاس ٔانرثخش ٔذأشٛش كصافح طاقح حضيح انهٛضس عهٗ عًق االَصٓاس ٖذى حساب انٕقد انالصو نهٕصٕل ال. (304) نهصذاء َٕع حٛس , ْزا تاالضافّ انٗ انعًق انعاَثٙ يع ذغٛش دسظاخ انحشاسج نًخرهف االصياٌ قثم ٔتعذ حذٔز عًهٛح االَصٓاس. انحاصم نكال انًادذٍٛ نٕحع عذو اسرًشاسٚح اَسٛاتٛح ذذسض دسظاخ انحشاسج تشكم ٔاضح عُذ االَرقال يٍ انطٕس انسائم انٗ انطٕس انصهة ٔرنك تسثة انحشاسج نقذ أضحد انُرائط انشٚاضّٛ . انكايُح نالَصٓاس ٔانضٚادج انحاصهح فٙ يعايم انرٕصٛم انحشاس٘ نهطٕس انصهة عًا ْٕ عهّٛ فٙ انطٕس انسائم .m6.10.ذٕافق ظٛذ يع انُرائط انعذدٚح تاسرخذاو طشٚقح انعُاصش انًحذدج انُاذعح يٍ نهحضيح انهٛضسٚح تطٕل يٕظٙ <4d6963726f736f667420576f7264202d2038302d3838cf20dae1c7c120e6dac7d5e320e6e4e6d1> al-khwarizmi engineering journal al-khwarizmi engineering journal,vol. 13, no. 4, p.p. 8088 (2017) biodegradation of diesel contaminated soil using single bacterial strains and a mixed bacterial consortium noor mohsen jabbar* estabriq hasan kadhim** alaa kareem mohammed*** *,*** department of biochemical engineering/ al-khwarizmi college of engineering/ university of baghdad/ iraq ** treatment and disposal of hazardous waste directorate/ ministry of higher education. and scientific. research *email: noormuhcin89@gmail.com **email: demaestabrriq91@gmail.com ***email: alaa_univ@yahoo.com (received 7 september 2017; accepted 3 october 2017) https://doi.org/10.22153/kej.2017.10.001 abstract this study was conducted to assess the hydrocarbon degradation abilities of sphingomonas paucimobilis, pentoae species, staphylococcus aureus, and enterobacter cloacae, which isolated from diesel contaminated soil samples. single strains and mixed bacterial consortia have been investigated their ability to degrade 1.0 % (v/v) of diesel oil in bushnellhaas medium as sole.carbon.and.energy.source. at temperature 30∘c, the individual.bacterial.isolates exhibited low growth and low degradation.than did the.mixed. bacterial.culture. after 28 days.of incubation the.combination.of four isolates degraded.an upper limit.of diesel 88.4%. this was. continued.by 85.1% by s. paucimobilis, 84 % by pentoae sp., 79% by s.aureus, and 74% by e. cloacae. for further evidence of the biodegradation effect of these isolates individually and as a mixed culture, which was supported by the use of technology chromatography confirming the occurrence of biodegradation. the results showed that the isolated bacteria are effective in biodegradation of diesel spills when used separately. it also confirmed the better biodegradability when used together in a mixed -culture. keywords: bioremediation, biodegradation, diesel, mixed-culture, pollution. 1. introduction petroleum hydrocarbons are the most common environmental pollutants in the world, and oil spills show a great hazard to terrestrial and aquatic ecosystems. oil pollution may arise either accidentally or operationally whenever oil is produced, transported, stored and treated, or when it is used on land or at sea. oil spills are a major threat to the environment because they severely damage surrounding ecosystems [1]. diesel is a medium distillate of petroleum hydrocarbons containing: normal alkanes, branched alkanes, olefins and small concentrations of polycyclic aromatic compounds [2]. as pollution of soil and groundwater through the uncontrolled release of petroleum products has become a major problem, a number of techniques have been tested to remediate contaminated sites[3]. bioremediation has emerged as one of the promising alternative treatment options for removing petroleum hydrocarbons because of its low cost and effectiveness. bioremediation is a method in which microorganisms are used for cleaning up process. they can be described as converting toxic and chemically complex organic compounds into non-toxic and simple inorganic compounds, such as co2 and h2o with the accumulation of microbial biomass, through oxidation under aerobic conditions [12]. microorganisms are considered to be efficient noor mohsen jabbar al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 8088 (2017) 81 biodegrades due to the wide variety of species, their abundance, and their catabolic and anabolic versatility, as well as their ability to adjust to adverse environmental conditions [4]. the biodegradation of petroleum .hydrocarbon requires a complicated metabolic route that is not always present in one type of microorganism but can be observed in a microbial consortium. numerous studies have been carried out on biodegradation of petroleum hydrocarbons using a mixed microorganism consortium [5]. in a mixed culture, the metabolic products of one type can be decomposed by another present in the culture and so on respectively, leading to a complete degradation of the substrate although there is no particular species of microorganisms in the community capable of destroying them alone[6]. in fact, since one species can metabolize only a limited range of hydrocarbon substrates, the group of many different bacteria, with wide enzymatic capacities, is usually involved in the degradation of petroleum hydrocarbons [7]. the aim of this study was to isolate local bacterial species that had the ability to decompose diesel and compare their biodegradability capabilities in single-use and mixed culture. 2. materials and methods 2.1. collecting of samples the soil contaminated with diesel was collected at a depth of 0-15 cm [8] from different locations, including al dura oil refinery and the local generators in baghdad city. all samples were kept in sterile nylon bags and transported to the laboratory to isolate and identify the bacteria. the diesel (light oil) was used in the experiment work from al dura oil refinery. 2.2. isolation of bacteria from diesel contaminated soil four grams of contaminated soil sample were suspended by a vortex mixer in 20 ml of sterile bushnell-haas medium containing (g/l): mgso4.7h2o, 1.0; k2hpo4, 1.0; kh2po4, 1.0; fecl3, 0.05; nh4no3, 1.0; cacl2, 0.02; ph to 7±0.2 and sterilized at 121oc for 15 min. bacteria were grown in 250 ml erlenmeyer flasks for one week in a cool shaker incubator at 30°c and 180 rpm. a loopful culture from the soil suspension was streaked on petri dishes containing nutrient agar. the plates are placed in an incubator at 30 ° c under aerobic conditions for 48 hours. specific colonies were isolated and sub-culture on nutrient agar plates and incubated for another 48 hours.the plates are then placed in the refrigerator at 4 °c for further study and identification [9]. 2.3. bacterial identification the colonies that were developed on nutrient agar were classified according to their shape, color and biochemical properties. the microscopic examination of the gram-stained slices is done to characterize gram-negative bacteria from others. then the identification of bacterial isolates was carried out in al-nokhba medical laboratory using vitek 2 device. 2.4. inoculum preparation bacterial strains were cultured on nutrient agar at 30 ° c for 48 h. aqueous culture was then suspended, standardizing to the macfarland scale tube number 7 [6]. tube 7 represents turbidity of bacteria in the concentration (2.1 x 109 cfu.ml1). 2.5. bacterial biomass to evaluate the produced bacterial biomass at the end of the incubation period a 10ml was taken from each flask and centrifugation at 10,000 rpm for 15 minutes. this biomass was washed with tetrachloride carbon (ccl4) and then with distilled water to remove the remaining hydrocarbons, then the air was dried up to the fixed weight [10]. 2.7. account the quantitative loss of diesel oil each of single and mixed bacterial culture was taken from.nutrient agar plate and suspended in 250ml conical flasks, each containing 100ml of sterile bushnell-haas medium with.1.0 (v/v) % diesel.as the sole carbon source. flasks were incubated in a cool shaker incubator at 180 rpm. the experiment conducted in duplicate and noninoculated flasks forms controls. all flasks were incubated for 28 days at 30∘c. then, to determine the remaining concentration of diesel oil after the end of incubation period, 15 ml of each flask was taken. samples extraction was carried out using carbon tetrachloride (ccl4). they were blended and put in a separating funnel with continuous shaking. the contents are then precipitated; two layers are formed: aqueous layer and ccl4 layer containing the remaining diesel oil [10]. noor mohsen jabbar al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 8088 (2017) 82 the last layer was poured and passed through the filter paper containing anhydrous sodium sulfates (na2so4). after ccl4 evaporation, the amount of residual diesel oil was measured in the medium by using (horiba oil analyzer ocma-350) device and the degradation efficiency was calculated according to equation (1): degradation rete % = ������ ����.�� ��������� ����.�� ��� ������ ����.�� ��� × 100 …(1) 2.6. the use of gas chromatography technique to detect the biodegradation of diesel the single and mixed bacterial culture were taken from a nutrient agar plate and suspended in 250ml conical flasks, each containing 100ml of sterile bushnell-haas medium with 1.0% (v/v) diesel as the sole carbon source. flasks were incubated in a cool shaker incubator at 180 rpm 30oc. the diesel...was extracted. from bushnellhaas medium. by liquidliquid extraction. method as follows:. (1 sample: 1chloroform). the sample was placed with chloroform in the separating funnel and shaking well after we allow the contents to be deposited. the bottom layer contains the residual concentration of diesel oil that will be withdrawn and tested using gas chromatography technology. the chromatographic gas device (gcshimadzu japanese company, model 2010) was fused silica capillary column se30 a 30m length, and equipped with flame ionization detector. the column temperature is programmed to rising from 100 ° c to 300 ° c and pressure 100 kpa. the detector temperature was 300°c and injector temperature was maintained at 290oc. the column temperature is programmed to rise from 100 ° c to 300 ° c at a rate of 3oc / min and pressure 100 kpa. nitrogen was used as the carrier gas[11]. 3. results and discussion 3.1 isolation and identification of hydrocarbons utilizing bacteria bacterial strains capable of decomposing diesel were isolated using bushnell-haas media to differentiate between hydrocarbons degrading bacteria and non-degraded bacteria. four different strains were isolated from the contaminated soil, which was designated as na-1, na-2, na-3, and na-4. morphological characteristics of isolated bacteria such as gram stain and biochemical tests were listed in table1. table 1, morphological characteristics, gram stain and biochemical tests (+) = positive result. (-) = negative result. colonies morphology of the isolates on nutrient agar and photomicrographs of staining of the isolates are shown in figure 1. on the basis of the vitek2 system, the bacteria were identified; na-1 as an enterobacter cloacae species, na-2 as a staphylococcus aureus, na-3 as a sphingomonas paucimobilis, na-4 as a pentoae species. the results of identification using the vitek 2 system are tabulated in table 2. table 2, identified bacteria using vitek 2 device. according to the previous studies of [12, 13] the strains of e.cloacae, s.aureus were reported to be isolated from oil contaminated soil and having the ability to utilize petroleum hydrocarbon as a sole source of carbon and energy. s. paucimobilis and pentoae sp. are often isolated from oilcontaminated soil because of their unique ability to decompose polycyclic aromatic hydrocarbons characteristics isolated bacterial colonies na-1 na-2 na-3 na-4 color of the colony creamy golden yellow off white pale yellow shape of the cell rod round rod rod gram's staining + motility motile nonmotile motile motile spore forming catalase test + + + + oxidase test + urease production test + + no. vitek 2 na-1 enterobacter cloacae na-2 staphylococcus aureus na-3 sphingomonas paucimobilis na-4 pentoae sp. noor mohsen jabbar al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 8088 (2017) 83 (pahs), which are important in on-site bioremediation [14, 15, and 16]. in this study, all the isolated bacteria were able to grow in sterile bushnell-haas medium and degrade diesel oil. this finding supports the increased function of these bacterial genera in hydrocarbon biodegradation. thus, these microorganisms could be effective in treatment of diesel spills in soil. fig. 1. colonies morphology and photomicrograph of isolated bacterial cultures na-1: enterobacter cloacae species, na-2: staphylococcus aureus, na-3: sphingomonas paucimobilis, na-4: pentoae sp. 3.2. dry weight (biomass) cell biomass quantities, in table (3), show the growth of bacterial isolates of e. cloacae, s.aureus, s. paucimobilis, and pentoae sp. in bushnell-haas medium .the results showed clearly that dry weight values at the end of incubationqperiod (as a result of biodegradation of diesel oil) in each single strain and mixture (combination of the four strains) were high also, na-1 na-2 na-3 na-4 noor mohsen jabbar al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 8088 (2017) 84 we noted the resulted dry weight of the mixed culture was high and more than the dry weight of each singular strain. this indicates that microorganisms have benefited from existing organic matter as the sole source of carbon and energy and these bacteria are highly efficient in diesel degradation. the results were agreed with precedent studies of [11] where the dry weight obtained was (3 g/l). bacterial isolates break down diesel oil to small compounds of carbon that used to produce polysaccharides, proteins, and fatty acids need for proliferation and energy production. the simple carbon compounds are merged into the new cellular ingredients, which means that they are used to make more microorganisms. therefore, carbon was used to create further biomass. table 3, cell biomass quantities. 3.3. the percentages of diesel decomposition by single and a consortium of isolates the biodegradation.percentage.of. diesel.by. the.four.isolates.and.their mixed culture.after. incubation. at. 30∘c for. 28 days was demonstrated in table 4. the results showed that the maximum degradation rate was achieved through a mixed bacterial culture up to (88.4%). these results clearly showed that the mixed culture could carry out a maximum degradation for diesel followed by s. paucimobilis, pentoae sp., s. aureus, and e. cloacae (85.1 %, 84 %, 79 %, and 74 % respectively). it was noted that mixed bacterial culture gave the highest rate of biodegradation because there is not a pure strain of bacteria with limited metabolism capacity for the decomposition metabolic of all components within diesel and a variety of physiological and metabolic factors required for the. biodegradation. of. different compounds.in diesel.... to put it more clearly the singular isolates metabolize a limited range of hydrocarbon substrates. and. dieselqoil.is. made. of. a. blend of. compounds,, so. the. biodegradation. of. it. needs. a mixture.of.different.bacterial groups..with broad enzymatic capabilities competent to degrade a wider range of hydrocarbons. in fact, a mixedculture of the bacterial community is required to complete the biodegradation of petroleum contaminants because the hydrocarbon mixture varies markedly in the volatility, solubility, tendency to biodegradable and the certain enzymes cannot be gained in a single organism. these observations are consistent with [10] who proved that after 28 days of incubation the mixed bacterial degraded up to 88.5% of crudeqoil. also, [16] concluded that the highest degree of degradation of diesel was observed in the treatment, when all three strains (pantoea sp. itsi10, pantoea sp. btrh79 and pseudomonas sp.) were inoculated in combination into soil contaminated with 30% diesel and the maximum hydrocarbon reduction was reached (79%). table 4, degradation of diesel oil. bacterial strain % of diesel oil degradation e. cloacae 74 s.aureus 79 s. paucimobilis 85.1 pentoae sp. 84 mixed culture 88.4 using chromatographic gas technology, it appears in the control sample (figure 2) having 13 chemicals material. (c9 – c21). after exposure diesel to e. cloacae, s.aureus, s. paucimobilis, and pentoae sp. individually as it's clear from the charts in the first week of the experiment the low molecular weight compounds were degraded extensively where some ingredients of the diesel, especially c9 c10 totally lost while c11 c20 was reduced hinting that biodegradation of the hydrocarbons components has happened (figure 3, 4, 5, 6). in the later days, and after two weeks, the visual checking of gas chromatography shows a significant demise of a number of peaks where the number of chemical ingredients decreased to 5, also lowered in the peak area of some components (figure 7, 8, 9, 10). these results coincide with the fact that microorganisms first attack low molecular weight hydrocarbons while attacking upper and middle hydrocarbons later during incubation. the different potential of isolates may vary in the process of diesel metabolism because of their differences in the enzymatic degradation systems of hydrocarbons. where some isolates have a strong affinity with the hydrocarbon components, some may be longdelayed due to the inhibitory components of diesel prior to the initiation of biodegradation. while in bacterial strain dry weight (g/100 ml) e. cloacae 0.2955 s. aureus 0.3685 s. paucimobilis 0.595 pentoae sp 0.367 mixed culture 1.226 noor mohsen jabbar al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 8088 (2017) 85 contrast, gc analysis of the total extract of diesel (figure 11) showed that the consortium caused a complete consumption of the major components. these results denote that the biodegradation rate of diesel has improved to a high level by added mixed bacterial culture. also, suggest that these bacteria have the ability to attack all components of hydrocarbons when being mixed culture [17]. therefore, the search of biodegradation by the bacterial consortium was essential because these mixed -cultures show metabolic diversity and superiority over pure-cultures. fig. 2. chemical compounds present in the control sample of diesel using gas chromatography. fig. 3. the residual chemical compounds in degraded diesel using enterobacter cloacae species after 7 days. fig. 4. the residual chemical compounds in degraded diesel using staphylococcus aureus species after 7 days. fig. 5. the residual chemical compounds in degraded diesel using sphingomonas paucimobilis after 7 days. fig. 6. the residual chemical compounds in degraded diesel using pentoae species after 7 days. noor mohsen jabbar al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 8088 (2017) 86 fig. 7. the residual chemical compounds in degraded diesel using enterobacter cloacae species after 28 days. fig. 8. the residual chemical compounds in degraded diesel using staphylococcus aureus after 28 days. fig. 9. the residual chemical compounds in degraded diesel using sphingomonas paucimobilis after 28 days. fig. 10. the residual chemical compounds in degraded diesel using pentoae species after 28 days. fig. 11. the residual chemical compounds in degraded diesel using bacterial consortium after 28 days. 4. conclusion the present study showed that the bioremediation with a mixed culture of enterobacter cloacae, staphylococcus aureus, sphingomonas paucimobilis, and pentoae species (consortium) was more efficient than a singular culture. the mixed bacterial culture can achieve the maximum degradation (88.4%) of studied diesel at 30 ° c after four weeks of incubation followed up by: 85.1% by s. paucimobilis, 84 % by pentoae sp., 79% by s.aureus, and 74% by e. cloacae. biodegradation of diesel oil means the transformation of its complex, harmful components like polycyclic aromatic hydrocarbons, and long chain alkanes into simpler nonpolluting fractions. noor mohsen jabbar al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 8088 (2017) 87 it is evident from this investigation that all thoughtful isolates have. a noted impact on the degradation of diesel oil. thus, this research could help to lighten the way for bioremediation studies and provide informationqthat allowsq the use of these isolates in biological treatment in environments contaminated with diesel oil. 5. references [1] a. m. r. al-taee, f. n. alkanany, s. a. gmais, and h. a. n. alshawi, “biodegradation of aliphatic hydrocarbons by bacteria isolated from khor al-zubair channel, southern iraq,” int. j. mar. sci., vol. 7, no. 18, pp. 176–182, 2017. [2] r. gopalakrishnan and c. v divya, “the pattern of degradation of diesel by acinetobacter species from diesel oil contaminated soil,” vol. 1, no. 5, 2014. [3] m. zhongyun, “bioremediation of petroleum hydrocarbon contaminated soil using indigenous cultures,” mernorial univ. neopfomdl., p. 111, 1998. [4] k. v. darsa and a. j. thatheyus, “biodegradation of petroleum compound using pseudomonas aeruginosa,” oalib, vol. 1, no. 5, pp. 1–9, 2014. [5] b. mrayyan and m. n. battikhi, “biodegradation of total organic carbons (toc) in jordanian petroleum sludge,” j. hazard. mater., vol. 120, no. 1–3, pp. 127– 134, 2005. [6] e. beraldo de morais and s. m. tauktornisielo, “brazilian archives of biology and technology biodegradation of oil refinery residues using mixedculture of microorganisms isolated from a landfarming,” arch. biol. technol. v, vol. 52652, no. 6, pp. 1571–1578, 2009. [7] s. santisi et al., “biodegradation of crude oil by individual bacterial strains and a mixed bacterial consortium,” brazilian j. microbiol., vol. 46, no. 2, pp. 377–387, 2015. [8] r. riffaldi, r. levi-minzi, r. cardelli, s. palumbo, and a. saviozzi, “soil biological activities in monitoring the bioremediation of diesel oil-contaminated soil,” water. air. soil pollut., vol. 170, no. 1–4, pp. 3–15, 2006. [9] a. o. nwadinigwe and e. g. onyeidu, “bioremediation of crude oil-polluted soil using bacteria and poultry manure monitored through soybean productivity,” polish j. environ. stud., vol. 21, no. 1, pp. 171–176, 2012. [10] r. s. al-wasify and s. r. hamed, “bacterial biodegradation of crude oil using local isolates,” int. j. bacteriol., vol. 2014, pp. 1– 8, 2014. [11] m. thamer, a. r. al-kubaisi, z. zahraw, h. a. abdullah, i. hindy, and a. a. khadium, “biodegradation of kirkuk light crude oil by bacillus thuringiensis, northern of iraq,” nat. sci., vol. 5, no. 7, pp. 865–873, 2013. [12] a. w. ahmed, f. s. alzubaidi, and s. j. hamza, “biodegradation of crude oil in contaminated water by local isolates of enterobacter cloacae enterobacter cloacae,” vol. 55, no. 3, pp. 1025–1033, 2014. [13] b. boboye, “degradative activity of bacteria isolated from hydrocarbon-polluted site in ilaje, ondo state, nigeria,” african j. …, vol. 4, no. 23, pp. 2484–2491, 2010. [14] l. zhou, h. li, y. zhang, s. han, and h. xu, “sphingomonas from petroleumcontaminated soils in shenfu, china and their pahs degradation abilities,” brazilian j. microbiol., vol. 47, no. 2, pp. 271–278, 2016. [15] s. p. story, e. l. kline, t. a hughes, m. b. riley, and s. s. hayasaka, “degradation of aromatic hydrocarbons by sphingomonas paucimobilis strain epa505.,” arch. environ. contam. toxicol., vol. 47, no. 2, pp. 168–76, 2004. [16] m. afzal, a. sessitsch, s. yousaf, t. g. reichenauer, and g. engineering, “international journal of phytoremediation the inoculation method affects colonization and performance of bacterial inoculant strains in the phytoremediation of soil contaminated with diesel oil,” no. june 2013, pp. 37–41, 2012. [17] m. l. riskuwa-shehu and u. j. j. ijah, “enhanced removal of crude oil in soil by mixed culture of bacillus megaterium ul05 and pseudomonas aeruginosa ul07,” vol. 4, no. 1, pp. 8–12, 2016. )2017( 80-88، صفحة 4، العدد13دجلة الخوارزمي الهندسية المجلم جبار نور محسن 88 ة وبشكل اتحاد سالالت بكتيرية بصورة منفرد لديزل الُملوث للتربة باستخداملالتحلل البايولوجي بكتيري مختلط **عالء كريم محمد* ** استبرق حسن كاظم * نور محسن جبار جامعة بغداد كلية الهندسة الخوارزمي/ قسم الهندسة الكيميائية االحيائية/،*** دائرة معالجة المخلفات/ وزارة العلوم والتكنولوجيا** yasmeensalih90@gmail.comااللكتروني:*البريد asemh2005@yahoo.com**البريد االلكتروني: alaauniv@yahoo.com***البريد االلكتروني: الخالصة sphingomonas paucimobilis enterobacter cloacae staphylococcus,كل من بهدف التعرف على مدى قابليةأُجريت هذه الدراسة aureus و pentoae species حيث تم عزل هذه السالالت من عينات التربة الملوثة بزيت الديزل. تم ,على التحلل البايولوجي للمركبات الهيدروكاربونية بوصفه مصدراً وحيداً من زيت الديزل %١بكتيري على تحليل خليطكل من هذه العزالت بصورة منفردة وبشكل ل البايولوجي التحلل التحقق من قابلية .bushnellhaas mediumفي وسط للكاربون ً يوم ٢٨حضانة مدّةوبعد c∘30عند درجة حرارة حالة اقل مما تم الحصول عليه منمعدل تحلل كذلكلعزالت المنفردة نمو منخفض واظهرت ا ،ا ً بمعدل التحلل لباقي ٪٨٨٫٤للمركبات الهيدروكاربونية بفعل االتحاد البكتيري بايولوجي حيث تم الوصول ألعلى معدل تحلل التأزر البكتيري متبوعا staphylococcusطة اسبو ٪٧٩و pentoae speciesطة اسبو ٪٨٤و sphingomonas paucimobilisطة اسبو ٪٨٥٫١لى التوالي : العزالت وع aureus طة اسبو ٪٧٤وenterobacter cloacae. خليط وللحصول على مزيد من األدلة على تأثير التحلل البيولوجي لهذه العزالت بشكل فردي وبشكل يولوجي اأظهرت النتائج أن البكتيريا المعزولة فعالة في التحلل الب .بكتيري، تم استخدام تقنية كروموتوغرافيا الغاز و التي أكدت حدوث التحلل البيولوجي ً خليطه بوصفيولوجي عند استخدامها معا اقابلية تحلل ب و بينت افضل عند استخدامها بشكل منفصل لزيت الديزللالنسكابات النفطية اً.بكتيري ا <4d6963726f736f667420576f7264202d20312d3130cacdd3ede420e6dae1ed20e6e3e5e4cf> al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 16, no. 1, march, (2020) p. p. 110 inverse kinematics analysis and simulation of a 5 dof robotic arm using matlab tahseen f. abaas* ali a. khleif** mohanad q. abbood*** *, **, *** department of production engineering and metallurgy/ university of technology/ baghdad/ iraq *email: 70047@uotechnology.edu.iq **email: 70080@uotechnology.edu.iq ***email: 70209@uotechnology.edu.iq (received 19 september 2019; accepted 3 december 2019) https://doi.org/10.22153/kej.2020.12.001 abstract kinematics is the mechanics branch which deals with the movement of the bodies without taking the force into account. in robots, the forward kinematics and inverse kinematics are important in determining the position and orientation of the end-effector to perform multi-tasks. this paper presented the inverse kinematics analysis for a 5 dof robotic arm using the robotics toolbox of matlab and the denavit-hartenberg (d-h) parameters were used to represent the links and joints of the robotic arm. a geometric approach was used in the inverse kinematics solution to determine the joints angles of the robotic arm and the path of the robotic arm was divided into successive lines to accomplish the required tasks of the robotic arm. therefore, this method can be adopted for engineering applications. matlab (graphical user interface) program was used to simulate the movement of the robotic arm in 3d. also, matlab (gui) has been used to view the position of each joint. the results showed that the maximum error in the x, y, and z coordinates of the end-effector were 0.0251 %, 0.0239 %, and 0.1085 % respectively. keywords: robotics, forward kinematics, inverse kinematics, d-h parameters, matlab. 1. introduction recently, the demands to use robots are increasing in many fields such as space, medical, industrial application, etc.. but the real challenge is the kinematics analysis of robot with higher dof [1]. the kinematic analysis contains two components: forward kinematics and inverse kinematics to study the movement of the robots. the forward kinematics is used to determine the position of the end-effector of a robot using the angles of the joints as inputs, while the position is used as input to determine the joint angles in inverse kinematics [2]. the simplest method to represent the robot links and joints to solve the forward kinematics is a denavid-hartenberg (dh) method [3]. on the other hand, there are many methods that are being used with inverse kinematics such as geometric approach, algebraic solution, and iterative solution [4]. a matlab program is one of the most programs used in many applications such as image processing, optimization, matrices, technical computing, etc.. robotic toolbox in matlab is used in determining the position of the end effector of the robotic arm and in simulating the movement of this robotic arm depending on the dh parameters [5, 6]. 2. related literature wathik i. m. al-tameemi and wael m. h. hadi [7] studied the forward and inverse kinematic analysis of a 5 dof robotic arm (labvolt 5250); where the dh parameters were used tahseen f. abaas al-khwarizmi engineering journal, vol. 16, no. 1, p.p. 110 (2020) 2 to solve the forward kinematics and the analytical solution was used with inverse kinematics analysis. matlab was used in both forward and inverse kinematics. the results showed that the maximum error in position was (0.5 %). tarun p. singh et al [8] presented the kinematic analysis (forward and inverse) of 6 dof manipulator arm. the analysis was performed using matlab, the dh parameters were used with forward kinematics and an iterative solution was used with inverse kinematics. an acceptable error was obtained from the comparison between the analytical results and software results. tahseen f. abaas and hind h. abdulridha [9] presented a modeling of a 5 dof robotic arm (lab-volt 5150) using the dh parameters and simulated the movement of the robotic arm using the matlab program. the comparison between matlab outputs and robocim outputs was performed to know the acceptance of the modeling of the robotic arm. alla n. barakat et al [10] studied the 3d simulation of a robotic arm using a matlab program depending on dh parameters. the results explained the way of achieving the desired goal of the work which was drawing sinewave on board. 3. kinematics analysis kinematics analysis of robots has defined the relationship between the links and joints with the position and orientation of the robot. the kinematics analysis is divided into forward kinematics and inverse kinematics. 3.1 forward kinematics forward kinematics is used to determine the position and orientation of the end-effector of the robotic arm from the specified joints angles. the dh method is one of the most methods used in forward kinematics which represents the relationship of the joint coordinate between two links as shown in figure (1). fig. 1. the dh frame. where: ai: link length. αi: link twist. di: link offset. θi: joint angle. the robotic arm used has 5 dof and the dh parameters of this robotic are listed in table (1). table 1, dh parameters for the robotic arm. link �� (mm) �� (degree) �� (mm) �� (degree) 1 0 90 105 �� 2 105 0 0 �� 3 100 0 0 � 4 0 90 0 � 5 0 0 150 �� also, the transformation matrix between two successive links can be obtained using the dh frame as follow: � � ��,�� ��,�� ��,�� ��,�� � � ��� ��� �� �� 0 00 00 00 0 1 00 1� 1 00 1 0 00 00 00 0 1 ! 0 1 " 1 00 1 0 # 0 00 00 0 1 00 1 " �1 00 �$ 0 0��$ 00 �$ 0 0 �$ 0 0 1� � � ��� ��� �$ �� �� �$ �� �$ # �� ��� �$ # �� 0 �$ 0 0 �$ ! 0 1 � …(1) where: �� � �%�&� ' tahseen f. abaas al-khwarizmi engineering journal, vol. 16, no. 1, p.p. 110 (2020) 3 �� � �()&� ' �$ � �%�&$ ' �$ � �()&$ ' the individual matrices and the global matrix of the 5 dof robotic arm can be obtained by substituting the dh parameters in table (1) in the equation (1), as showed in figure (2): fig. 2. the coordinate frame of the robotic arm. *�+ � ��,�, ��,�, ��,�, ��,�, *�+ � ��� 0�� 0 �� 0��� 00 10 0 0 !� 0 1 � …(2) *�� � ��� ����� �� 0 #���0 #���0 00 0 1 00 1 � …(3) * � � �� �� � � 0 # � 0 # � 0 00 0 1 00 1 � …(4) * � �� 0� 0 � 0�� 00 10 0 0 0 0 1� …(5) *� � ��� ����� �� 0 00 00 00 0 1 !�0 1 � …(6) and the global matrix *�+: *50 � *10 *21 *32*43*54 *50 � 111 112121 122 113 114123 124131 1320 0 133 1340 1 " …(7) 1�� � ��� � + ��� 1�� � ������ + ���� 1� � ���� 1� � ��&!��� + # �� + #���' 1�� � ���� � � ���� 1�� � ������ � ��� 1� � ���� 1� � ��&!��� + # �� + #���' 1 � � ���� 1 � � ����� 1 � ��� 1 � �!��� + # �� + #��� + !� where: ��� � � �%�&�� + �� + � + � + ��' ��� � �()&�� + ��' 3.2 inverse kinematics inverse kinematics (ik) is used to determine the required joints angles of the robotic arm to achieve the specified position and orientation of the end-effector of the robotic arm. in this work, the geometric approach was used to solve the inverse kinematics of the 5 dof robotic arm: tahseen f. abaas al-khwarizmi engineering journal, vol. 16, no. 1, p.p. 110 (2020) 4 fig. 3. the 4 link articulated robot [9]. from figure (3), the wrist angle relative to the reference coordinate (θ234) represents the relation between (θ2, θ3, and θ4): �� � �� + � + � …(8) where �� can be calculated based on pitch wrist orientation angle ∅ 90 � �� � ±∅ …(9) � � !� ∗ cos ∅ …(10) :�; � :� � � cos �� � <= …(11) :>; � :> � � sin �� � a= …(12) :�; � :� + !� sin ∅ � b= …(13) �= � c:�� + :>� � � � c:�;� + :>;� …(14) d � ce:�; � !�f� + �=� …(15) fig. 4. top view of the robotic arm. • solution for �g: base angle can be calculated from figure 4 as follows: �� � tanj� klmlno …(16) the other solution will be: ��p � �� + 180 …(17) • solution for �r: by using the law of cosines: # � � d� + #�� � 2#� d cos&s' ⇒ s �cosj� kuvw�vvj�xv��v u o …(18) y � tanj� klz;j�,[; o ...(19) �� � y ∓ s …(20) • solution for �]: d � ^&#�� + # � � 2#�# cos&_ � � '' …(21) � � ± cosj� kuvj�vvj�xv��v�x o …(22) • solution for �`: � � �� � �� � � …(23) 4. simulation matlab graphical user interface (gui) was used in this work to perform many functions as shown in figure (5). it illustrated the inputs to the program was the position of the end-effector of the robotic arm while the outputs were the joints angles of the robotic arm and the position of each joint. also, a 3d simulation of the robotic arm movement was presented in gui as an output. the program was performed as in the following steps: • setting the position (:� ‚ :>‚ #)! :�' of the goal relative to the base of the robotic arm as inputs. tahseen f. abaas al-khwarizmi engineering journal, vol. 16, no. 1, p.p. 110 (2020) 5 • a function used to determine the joints angles of the robotic arm using the equations (8) to (23). • a function used to determine the position of each joint of the robotic arm using the equations from (2) to (6). • 3d simulation to the movement of the robotic arm was applied using the robotics toolbox in matlab depending on the dh parameters. fig. 5. the window of the gui program. 5. results and discussions to test the efficiency of the geometric approach in the inverse kinematics analysis, several cases were studied. the inputs to the gui program, shown in figure (5), were the position of the goal (:� , :>, #)! :�) and the outputs were the joints angles of the robotic arm. the 3d representation of the robotic arm depending on the dh parameters is shown in figure (6) and figure (7). the 3d representation illustrates four cases. the extracted angles of joints were applied in equation (7) to determine the position of the endeffector and compare these results with the input results. the errors between them were obtained and listed in table 2 to indicate the efficiency of the program used. the algorithm of the geometric approach was developed for the inverse kinematic analysis of the robotic arm and compared the results of this method with results extracted using an algebraic solution. there was a large match in these results, so the geometric approach method was applied. tahseen f. abaas al-khwarizmi engineering journal, vol. 16, no. 1, p.p. 110 (2020) 6 case (1) case (2) tahseen f. abaas al-khwarizmi engineering journal, vol. 16, no. 1, p.p. 110 (2020) 7 case (3) case (4) fig. 6. gui for four cases. tahseen f. abaas al-khwarizmi engineering journal, vol. 16, no. 1, p.p. 110 (2020) 8 fig. 7. the movement of the robotic arm of four cases. table 2, the error of the end-effector position case no. end-effector position true (mm) joint angle measured (degree) end-effector position measured (mm) bcdefghi jkkek� lmkgi � ni�dgki�mkgi l o gpp% 1 rs � rrp �g �36.1973 �r �69.9029 �] �-43.1499 �` �52.2469 �t �90 rs � rgu. uuwx 0.0006 ry � gxg ry � gxg. pg`x 0.009 rz � rrp rz � rgu. uu]` 0.003 2 rs � �r]p �g �165.1461 �r �89.9426 �] �-65.6204 �` �53.6778 �t � up rs � �r]p. pgp] 0.0045 ry � xg ry � xp. uwxg 0.023 rz � rrp rz � rgu. uux` 0.0016 3 rs � rrp �g �15.4972 �r �95.1123 �] �-70.5272 �` �53.4149 �t � up rs � rrp. ptt] 0.0251 ry � xg ry � xp. uwt` 0.0239 rz � rrp rz � rrp. r]wx 0.1085 4 rs � �r]p �g �154.2376 �r �81.8983 �] �-60.124 �` �58.2257 �t � up rs � �r]p. p`u] 0.0214 ry � ggg ry � ggg. pgrg 0.0109 rz � rrp rz � rrp. g{g] 0.0778 case (1) case (4) case (3) case (2) tahseen f. abaas al-khwarizmi engineering journal, vol. 16, no. 1, p.p. 110 (2020) 9 from the results of the error in table (2), indicated the little small error occurred in the position of the end-effector of the robotic arm that confirms the effectiveness of the program used, where the maximum error in the x, y, and z coordinates of the end-effector were (0.0251 %, 0.0239 %, and 0.1085 %) respectively. 6. conclusions in this work, the inverse kinematics analysis of 5 dof robotic arm was accomplished using the matlab gui program. the results indicated the used of the geometric approach in inverse kinematics analysis to determine the joints angles of the robotic arm was effectively and the position of each joint was determined in the gui program and show it. a 3d simulation for the movement of the robotic arm was performed depending on the dh parameters in representing the links and joints of the robotic arm to help in understanding and representing the movement of the robotic arm. the curve of the second, third, fourth, and etc. degree can be adopted as the path of the endeffector of the robotic arm by dividing this curve into many small lines to enable the end-effector to perform the required curve path. 7. references [1] s.s kamlesh and r. mishra, “advanced path simulation of a 5r robotic arm for ct guided medical procedures”, materials today: proceedings 5, pp 6149-6156, 2018. [2] h. m. al-khafaji and m. j. jweeg , “solving the inverse kinematic equations of elastic robot arm utilizing neural network”, al-khwarizmi engineering journal, vol. 13, no. 1, pp 13-25, 2017. [3] i. s. karem , t. a.j. wahab , and m. j. yahyh, “design and implementation for 3-dof scara robot based plc”, al-khwarizmi engineering journal, vol. 13, no. 1, pp 40-50, 2017. [4] s. dereli and r. köker , “design and analysis of multi-layer artificial neural network used for training in inverse kinematic solution of 7dof serial robot”, gaziosmanpasa journal of scientific research, vol. 6, pp 60-71, 2017. [5] d. l. rajnor,and a. s. bhide, “automatic material handling system using pick & place robotic arm & image processing”, international journal for scientific research & development, vol. 2, issue 5, pp 168-171, 2014. [6] d. sivasamy, m. d. anand , and k. a. sheela , “robot forward and inverse kinematics research using matlab”, international journal of recent technology and engineering, vol. 8, issue 2s3, pp 29-35, 2019. [7] w. i. m. al-tameemi and w. m. h. hadi , “kinematics analysis of 5250 lab-volt 5-dof robot arm”, eng. & tech. journal, vol. 32, part a, no. 9, pp 2196-2204, 2014. [8] t. p. singh, p. suresh, and s. chandan, “forward and inverse kinematic analysis of robotic manipulators”, international research journal of engineering and technology, vol. 4, issue 2, pp 1459-1469, 2017. [9] t. f. abaas, and h. h. abdulridha, “inverse kinematic analysis of lab-volt r5150 robot system”, international journal of research, vol. 4, issue 13, pp 81-88, 2017. [10] a. n. barakat, k. a. gouda, and k. a. bozed, “kinematics analysis and simulation of a robotic arm using matlab”, 4th international conference on control engineering & information technology”, 1618 december, 2016, hammamet, tunisia. )2020( 110، صفحة 1العدد ، 16دجلة الخوارزمي الهندسية المجلمتحسين فاضل عباس 10 التحليل الحركي العكسي والمحاكاة لذراع روبوت ذو خمس درجات لحرية الحركة بأستخدام matlab مهند قصي عبود*** علي عبار خليف** تحسين فاضل عباس* العراق /بغداد /الجامعة التكنولوجية /*، **، *** قسم هندسة االنتاج والمعادن uotechnology.edu.iq@70047االلكتروني: *البريد uotechnology.edu.iq@70080البريد االلكتروني: ** uotechnology.edu.iq@70209البريد االلكتروني: *** الخالصة التحليل الحركي االمامي والعكسي يعد الروبوتات، في. االعتبار في القوة أخذ دون األجسام حركة مع يتعامل الذي الميكانيكي الفرع هو التحليل الحركي لحرية الحركة روبوت ذو خمس درجات يستعرض هذا العمل التحليل الحركي العكسي لذراع. متعددة بمهام للقيام واتجاهه الماسك موضع تحديد مهم في استخدم. الروبوت ذراع أذرع ومفاصل لتمثيل) (denavit-hartenberg متغيرات واستخدمت matlab برنامج في robotics toolbox باستخدام المهام إلنجاز متتالية خطوط إلى اآللي الذراع مسار تقسيم لذراع الروبوت وتم المفاصل التحليل الحركي العكسي اليجاد زوايا حل في الهندسي النهج ثالثية لمحاكاة) الرسومية المستخدم واجهة( matlab برنامج يستخدم .الهندسية للتطبيقات الطريقة هذه اعتماد اآللية، وبالتالي، يمكن للذراع المطلوبة األقصى الحد أن النتائج أظهرت. لمفص كل موقع لعرض matlabلحركة ذراع الروبوت .أيًضا، تم أستخدام واجهة الرسوم الحاسوبية ببرنامج األبعاد .التوالي على٪ ٠٫١٠٨٥ و ،٪ ٠٫٠٢٣٩ ،٪ ٠٫٠٢٥١ للماسك هي x ،y ،z إحداثيات في للخطأ the inverse solution of dexterous robot by using neural networks ١ the inverse solution of dexterous robot by using neural networks dr. bahaa ibraheem kazem samer yahya hadi mechatronics dept al-kwarizmi college of engineering control and computers engineering university of baghdad,, iraq, university of technology, iraq (received 1٣ june 200٦; accepted 19 december 2006) abstract: the inverse kinematics of redundant manipulators has infinite solutions by using conventional methods, so that, this work presents applicability of intelligent tool (artificial neural network ann) for finding one desired solution from these solutions. the inverse analysis and trajectory planning of a three link redundant planar robot have been studied in this work using a proposed dual neural networks model (dnnm), which shows a predictable time decreasing in the training session. the effect of the number of the training sets on the dnnm output and the number of nn layers have been studied. several trajectories have been implemented using point to point trajectory planning algorithm with dnnm and the result shows good accuracy of the end effector position for the desired trajectory. keywords: inverse kinematics, robotics, neural network introduction: the kinematics is the science of motion, which deals with motion without consideration of the forces that cause it. within the science of kinematics one should study the position, velocity, acceleration, and all higher order derivatives of the position variables (with respect to time or any other variable(s)). hence, the study of the kinematics of manipulators refers to all the geometrical and time-based properties of the motion. the relationships between these motions and the forces and torques, which cause them, are the problem of dynamics [1]. there are two types of kinematics: the forward and inverse kinematics. the forward kinematics problem can be stated as follows: given the joint variables of the robot, one can determine the position and orientation of the end effecter. the joint variables are the angles between the links in the case of revolute or rotational joints, and the link extension in the case of prismatic or sliding joints. the forward kinematics problem is to be contrasted with the inverse kinematics problem, which can be stated as follows: given a desired position and orientation for the endeffecter of the robot, one can determine a set of joint variables that achieve the desired position and orientation [2]. execution of a task by a robot generally requires many movements of its end effecter. the set of situations corresponding to these moves define the geometrical trajectories of the operations space. a trajectory is, therefore defined by the application and the geometrical constraints of the robot and its environment. a distinction is generally made between point-topoint trajectories and continuous path trajectories, depending on the number of geometrical constraints applied to the trajectory. motion results from a particular parametric description of the trajectory where the parameter is time [3]. if the number of joints of the robotic arm exceeds the dimension of the toolconfiguration space, then robotic arm is said to alkhwarizmi engineering journal alkhwarizmi engineering journal , vol. 3 , no.1 , pp 1-11 (2007) dr. bahaa ibraheem kazem /al-khwarizmi engineering journal ,vol.3, no.1, pp 1-11 (2007) ٢ be kinematically redundant. robots with more than six axes are always kinematically. redundant. however it is also possible for robots with fewer axes to be redundant if the dimension of the tool-configuration space is restricted [4]. dexterity has been interpreted to mean different physical concepts such as a measure of kinematics feature over which a manipulator can kinematically reach all orientations, the operation of manipulators with multiple, actively powered fingers, and a global measure applied over a complete end-effecter trajectory. in one way or another, the aim of considering dexterity is to lead to robots which are similar to the human arm since many desirable features are ingeniously integrated in it and apparently constitutes the ultimate model of a dexterous robot. a dexterous device would have many sensors since a high level understanding of the situations is of the extreme importance to achieve complex tasks. it would have many degrees of freedom (dof), may be more than a complete human arm [5]. there are many references that deal with robot kinematics and trajectory planning; some of them are mentioned below: robot kinematics generally includes forward and inverse kinematics at the position, velocity, and acceleration level. these constructs are essential for the cartesian control of serial manipulators. c. kapoor and d. tesar [6] presented the development of a c++ class library that supports the forward and inverse kinematics of all possible geometries of serial manipulators. object-oriented analysis and design are the primary software development methodology used. application of this methodology led to the sub-division of the kinematics domain into forward and inverse kinematics. analysis of these sub-domains resulted in their further sub-division, identification of abstract components, development of classes, interface specifications, and finally implementation and testing. an approach to solve the inverse kinematics problem for hyper-redundant planar manipulators following any desired path was presented by f. m. asi [7], his approach is based on defining virtual layers and dividing them into virtual/real three-link or four-link sub-robots. this approach starts by solving for the inverse kinematics problem for the subrobot located in the lowest virtual layer. the data obtained from the solution of this subrobot are used to solve the inverse kinematics equations for the sub-robots located in the upper virtual layers. the data obtained by solving the equations of the sub-robots located in each virtual layer affect the solutions of the equations of the sub-robots located in both the upper and lower virtual layers. by j. somlo, a. sokolov, and v. lukanyin [8] carried out an attempt in order to develop an automatic trajectory planning. it is shown that different approaches to trajectory planning are possible. these are 1. time optimal 2. process optimal 3. force effective 4.optimal trapezoidal trajectory planning. realization of all these trajectory-planning principles can be automatized. s. yue and d. henrich [9] focused on the problem of point-to-point trajectory planning for flexible redundant robot manipulators (frm) in joint space. compared with irredundant flexible manipulators, a frm possesses additional possibilities during pointto-point trajectory planning due to its kinematics redundancy. a trajectory planning method to minimize vibration and/or executing time of a point-to-point motion is presented for frm based on genetic algorithms (gas). kinematics redundancy is integrated into the presented method as planning variables. quadrinomial and quintic polynomial are used to describe the segments that connect the initial, intermediate, and final points in joint space. the trajectory planning of frm is formulated as a problem of optimization with constraints. a method for solving the inverse kinematics of a humanoid robot based on artificial neural networks is presented by j. de lope, t. zarraonandia and d. maravall [10]. the inputs of the network are the desired positions and dr. bahaa ibraheem kazem /al-khwarizmi engineering journal ,vol.3, no.1, pp 1-11 (2007) ٣ fig.1. intermediate point on the point-to-point path. orientations of one foot with respect to the other foot. the output is the joint coordinates that make it possible to reach the goal configuration of the robot leg. trajectory planning trajectory refers to a time history of position, velocity and acceleration. suppose that the point-to-point trajectory is connected by several segments with continuous acceleration at the intermediate via point (as shown in figure 1). the intermediate points can be given as particular points that should be passed through. this is useful especially when there are obstacles in the working area. if one wishes to be able to specify the position, velocity, and acceleration at the beginning and the end of a path segment, a quadrinomial and a quintic polynomial are required. let us assume that there are pm intermediate via points between the initial and the final points. between the initial points to pm intermediate via points, a quadrinomial is used to describe these segments as [9]; ( ) aitiaitiaitiaiaitx ii 43322101, ++++=+ (1) (i=0,…. pm-1) (2) (ai0,…,ai4) are constants and ti is the time from the last intermediate point to the moment. the constrains are given as: ax ii 0= (3) tiait iaitia itia ia ixi 443322101 ++++=+ (4) a ixi 1=& (5) t ia it ia it ia ia ixi 3442332211 +++=+& (6) a ix i 22=&& (7) where ti is the executing time from point i to point i +1. the five unknowns can be solved as: xa ii =0 (8) xa ii &=1 (9) 2/2 xia i &&= (10) t it ixit ixi xit ixixi a i 3/23 4114 3         −− −+−+ = &&& & (11) titixitixi xixitixi ai 4/ 2/22 3131 4         ++ ++−+ = &&& & (12) the intermediate point i +1’s acceleration can be obtained as: tia itia ia ixi 241236221 ++=+&& (13) the segment between the number pm of intermediate points and the final point can be described by quitic polynomial as: ( ) t ibit ibi bit ibit ibibitx ii 5544 322101, ++ +++=+ (14) where (i= pm) and the constraints are given as: bixi 0= (15) tibitibi tibitibitibibixi 5544 3322101 ++ +++=+ (16) bixi 0=& (17) tibitibi tibitibibixi 455344 2332211 + +++=+& (18) bixi 22=&& (19) dr. bahaa ibraheem kazem /al-khwarizmi engineering journal ,vol.3, no.1, pp 1-11 (2007) ٤ tibitibi tibibixi 35202412 36221 + ++=+&& (20) and these constraints specify a linear set of six equations with six unknowns whose solution is: xibi =0 (21) xibi &=1 (22) 2/2 xibi &&= (23) t i t ixi xi t i ixi xi xixi bi 32/ 2 1 3 12 18 20120 3                 +− −         + + −−+ =      && && & & (24) ( ) t i t ixi xi t i ixi xi xixi b i 42/ 2 12 3 16 114 13030 4             + − +      + + ++− = && && & & (25) ( ) t i t ixi xi t i ixi xi xixi bi 52/ 2 16 16 12112 5             + − −         + + − −+ = && && & & (26) using neural networks in robot kinematics from above, it is clear that in order to perform end effecter position control of a robotic manipulator, two problems need to be solved [11]: 1. inverse kinematics problem: given the cartesian coordinates of the end effecter, specified either as a single point or as a set of points on a trajectory, joint angles need to be found. 2. target position control: given the final end effecter position, a joint angles sequence suitable for achieving the final position needs to be found. in this work a dual nn model has been designed in order to find the inverse solution for three degrees of freedom redundant planner robot. each architecture of these nn exist of three layers backpropagation networks. the first network is used to find the joint angles to reach the desired point when it located in the circular work area with a maximum radius equal to (rmax/2) or (maximum reach/2). the second network is used to find the joint angles associated with remaining points in the robot work area, that means (maximum reach/2) ≤ r ≤ (maximum reach). each of these two networks has three layers. there are nineteen input vectors with two elements, and there are ten neurons in the first hidden layer, twenty five neurons in the second hidden layer and three neurons in the third (output) layer. the transfer functions in the input and output layers are (purelin) and the hidden layer transfer functions are (logsig). case studies a planar articulated robot with three links is used in the following case studies. the robot has one redundant freedom in terms of positioning. the first link has the length of (l1=4 unit), the second link has the length of (l3=3 unit), and the third link has the length of (l2=2 unit). all the cases are simulated in the horizontal plane. inverse kinematics if the global angle (q3) which is equal to the summation of the three local angles (θ1,θ2,θ3) takes any random value then the x and y coordinates of the end of second link can be easily found by using the conventional inverse solution[1], where r r 21 tan 12 −± −=θ (27) where r can be found from: ll lldydx r 2 2 2 12 2 2 2 1 22 2 −−+ = (28) cll sl dx dy 221 22tan 1tan 11 + −−−=θ (29) q3= θ1+θ2+θ3 (30) dr. bahaa ibraheem kazem /al-khwarizmi engineering journal ,vol.3, no.1, pp 1-11 (2007) ٥ -3 -2 -1 0 1 2 3 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 the x-coordinate of target point th e yco or di na te o f t ar ge t p oi nt -3 -2 -1 0 1 2 3 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 the x-coordinate of target point th e yco or di na te o f t ar ge t p oi nt then θ3= q3θ1-θ2 where dx & dy are the x and y coordinates of the end of the second link. it is clear from the previous equations that there are two solutions for any value of q3, but there are infinite possibilities for the value of q3, hence there are infinite solutions to the three links arm to reach any point inside the work space, therefore the neural network is used to find one desired solution. to find the joint angles of the articulated robot in order to reach the point of (x = -2.2 unit) and (y = 4.6 unit), figure (2) shows the solution of this case. fig. 2 .the end effecter at point (x=-2.2 unit) and (y=4.6 unit) (a) two hidden layers n.n. and (19) training sets (b) two hidden layers n.n. and (37) training sets (c) single layer n.n. and (19) training sets (d) single layer n.n. and (37) training sets the tables (1) & (2) show the value of error by using the n.n. technique: where the error was found by using the following equation: where xd : the desired x-coordinate of target point. xnn : the x-coordinate of the target point from the neural networks. yd : the desired y-coordinate of target point. ynn : the y-coordinate of the target point from the neural networks. table (1) error by using two hidden layers n.n. no.of t.s. θ1(deg) θ2(deg) θ3(deg) 19 49.6488 118.0402 -12.1608 37 50.0103 117.2505 -12.4518 xd (unit) yd(unit) xnn (unit) ynn(unit) error (unit) -2.2 4.6 -2.1608 4.5180 0.090 9 -2.2 4.6 -2.1653 4.5770 0.041 4 table (2) error by using single layer n.n. no.of t.s. θ1(deg) θ2(deg) θ3(deg) 19 51.2902 116.3237 -13.6137 37 50.4623 117.4577 -13.3115 xd (unit) yd(unit) xnn (unit) ynn(unit) error (unit) -2.2 4.6 -2.2263 4.6415 0.049 1 -2.2 4.6 -2.1940 4.5703 0.030 3 point to point trajectory planning in first case study the training sets are (19) and the network used is a two hidden layers n.n., where the end effector is moved from the start point (x=-3, y=-5, vx=1, vy=2, ax=1, ay=0) to the target point (x=5, y=2, vx=0, vy=0, ax=0, ay=0) but the end effector is passing through the intermediate point (x=1, y=-2, vx=2, vy=1) and the desired time for moving the end effector from the first point to the intermediate point is (2 second), and the time for moving the end effector from the intermediate point to the target point is (3 second).by using the equations of the trajectory planning, the (x) and (y) coordinates, and their first and second derivatives with time can be found. the desired path of the end effecter from the first point to the target point passing (a) (b) (c) (d) ( ) ( )       −+−= ynnydxnnxde 22 dr. bahaa ibraheem kazem /al-khwarizmi engineering journal ,vol.3, no.1, pp 1-11 (2007) ٦ -3 -2 -1 0 1 2 3 4 5 -5 -4 -3 -2 -1 0 1 2 x(m) through the intermediate point is shown in figure (3) fig. 3. the desired point-to-point path the x & y coordinates of the desired path with time are shown in figure (4): fig. 4 .the x & y coordinates of desired path with respect to time the first time derivative of the x & y coordinates, i.e. (vx)&(vy) with respect to time is shown in figure (5): fig. 5 .vx & vy versus time the second time derivative of the x & y coordinates, i.e. (ax) & (ay) with respect to time is shown in figure (6): fig. 6. ax & ay versus time the first, second & third joints angle with respect to time are shown in figure (7): fig. 7. θ1, θ2 & θ3 versus time figure (8) shows both of the real and desired paths of the arm. x(unit) x(unit) vx(unit/s) vx(unit /s) ax(unit /s2) ay(unit /s2) θ3(deg) θ2(deg) θ1(deg) x(unit) y(unit) n.n. path desired path y(unit) dr. bahaa ibraheem kazem /al-khwarizmi engineering journal ,vol.3, no.1, pp 1-11 (2007) ٧ fig. 8 .the real and desired paths of the arm the configuration of the three links planar articulated robot is shown in figure (9). fig. 9. the configuration of the arm to find the error between the desired trajectory and neural network trajectory, one can calculate the error between some points along them. it is the best method to find the accuracy of the neural network method; there are forty one points along the desired trajectory and neural network trajectory which are used to find the error, where the error in each point is found by using the equation (31).figure (10) shows the error versus the distance of the end effector from the base. 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 r(m) fig.10 .the error versus the distance from the base the second case is similar to the previous case but the training sets are (37) and the network used has a two hidden layers n.n., where the end effector is moved from the start point (x=-3, y=-5, vx=1, vy=2, ax=1, ay=0) to the target point (x=5, y=2, vx=0, vy=0, ax=0, ay=0) but the end effector is passing through the intermediate point (x=-1, y=-2, vx=2, vy=1) and the desired time for moving the end effector from the first point to the intermediate point is (2 second), and the time for moving the end effector from the intermediate point to the target point is (3 second). the first, second & third joints angle with respect to time are shown in figure (11): 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 -250 -200 -150 -100 -50 0 50 100 150 time(sec) fig. 11. θ1, θ2 & θ3 versus time figure (12) shows both of the real and desired paths of the arm. -3 -2 -1 0 1 2 3 4 5 -5 -4 -3 -2 -1 0 1 2 3 x(m) fig. 12. the real and desired paths of the arm x(unit) y(unit) r(unit) error θ1(deg) θ2(deg) θ3(deg) y(unit) x(unit) n.n. path desired path dr. bahaa ibraheem kazem /al-khwarizmi engineering journal ,vol.3, no.1, pp 1-11 (2007) ٨ the configuration of the robot is shown in figure (13); figure (14) shows the error versus the distance of the end effector from the base. fig. 13 .the configuration of the arm 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 fig 14. the error versus the distance from the base the same case is studied by using the single layer nn instead of two hidden layers nn, when the training sets are (15) we got the results shown in the following figures. and when the training sets are (37) we got the results shown in the following figures. 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 -250 -200 -150 -100 -50 0 50 100 150 time(s) an gl es (d eg ) fig.15. θ1, θ2 & θ3 versus time fig. 16. the real and desired paths of the arm -3 -2 -1 0 1 2 3 4 5 -5 -4 -3 -2 -1 0 1 2 x(unit) y(unit) n.n. path desired path y(unit) x(unit) r(unit) θ 3(deg) θ1(deg) θ2(deg) dr. bahaa ibraheem kazem /al-khwarizmi engineering journal ,vol.3, no.1, pp 1-11 (2007) ٩ -4 -3 -2 -1 0 1 2 3 4 5 -5 -4 -3 -2 -1 0 1 2 3 x(unit) y( un it) f ig. 17. the configuration of the arm 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 r(unit) er ro r(u ni t) fig. 18 .the error versus the distance from the base 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 -250 -200 -150 -100 -50 0 50 100 150 time(s) an gl es (d eg ) figure 19 θ1, θ2 & θ3 versus time fig.20 .the real and desired paths of the arm conclusions the major observations of this work can be summarized as follows: § for a redundant robot the inverse kinematics has infinite number of solutions, but § when using the neural network method there is only one desired solution from these infinite § solutions, since the training session is done using the non-singular set of solution. -4 -3 -2 -1 0 1 2 3 4 5 -6 -5 -4 -3 -2 -1 0 1 2 3 x(unit) y( un it) fig. 21. the configuration of the arm -4 -3 -2 -1 0 1 2 3 4 5 -6 -5 -4 -3 -2 -1 0 1 2 x(unit) y(unit) θ2(deg) θ3(deg) θ1(deg) n.n. path desired path dr. bahaa ibraheem kazem /al-khwarizmi engineering journal ,vol.3, no.1, pp 1-11 (2007) ١٠ 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 0 0.05 0.1 0.15 0.2 0.25 r(unit) er ro r(u ni t) fig. 22. the error versus the distance from the base § in conventional methods for the inverse kinematics, one must find the joint space singularity in order to avoid it, but when using the neural network method there is no need to find the joint space singularity because this method gives one desired solution only. § since the neural network method is an approximation method, the results show that the obtained solution from the proposed neural network model is depends on the initial weights in training session. i.e. the use of a neural network decreases the repeatability for kinematics solution of the manipulator arm. references [1] john j. craig "introduction to robotics mechanics and control",1986. [2] mark w. spong and m. vidyasagar, "robot dynamic and control", john wiley and sons, inc., 1989. [3] alain liegeois "robot technology: performance and computer-aided design", volume 7, prentice-hall, 1985 . [4] jacobsen, s.c., iversen, e.k., knutti, d.f., johnson, r.t., and biggers, k.b., "design of the utah/mit dexterous hand," in proc. ieee int. conf. robotics and automation, san francisco, pp. 1520-1532, april 7-10, 1986. [5] e. s. conkur "real time path planning and obstacle avoidance algorithms for redundant manipulators", ph.d. thesis, department of mechanical engineering, university of bristol, september 1997. [6] chetan kapoor and delbert tesar "kinematics abstraction for general manipulator control", robotics research group, the university of texas at austin, jjprc/merb 1.206, mail code r9925, austin, texas 78712-1100, 1990. [7] farshid magami asi "analysis of hyper redundant manipulators", m.sc. thesis, mechanical engineering department, villanova university, august 1998. [8] j.somlo, a.sokolov, v.lukanyin "intelligent robot control. the automation trajectory planning", department of manufacturing engineering, budabist, university of technology and economics, 2002. [9] shigang yue and dominik henrich "point-to-point trajectory planning of flexible redundant robot manipulators using genetic algorithms", embedded systems and robotics (resy), informatics faculty, university of kaiserslautern, d-67653 kaiserslautern, germany, 2001. [10] javier de lope, telmo zarraonandia, rafaela gonzalez-careaga, and dario maravall "solving the inverse kinematics in humanoid robots: a neural approach", department of artificial intelligence, faculty of computer science, university of dr. bahaa ibraheem kazem /al-khwarizmi engineering journal ,vol.3, no.1, pp 1-11 (2007) ١١ politecnica de madrid, campus de montegancedo, 28660 madrid, spain, 2004. [11] jack m. zurada "introduction to artificial neural systems", jaico publishing house, 1996. الحل العكسي لذراع انسان الي متعدد زوایا الوصول بأستخدام الشبكات العصبیة الدكتور بھاء ابراھیم كاظم الباحث سامر یحیى ھادي قسم ھندسة السیطرة والنظم قسم ھندسة المیكاترونكس الجامعة التكنولوجیة جامعة بغداد –كلیة ھندسة الخوارزمي :الخالصة ل ذراع الی ة ) inverse kinematics solutions( م ن الحل ول العكس یة (infinity)ھنال ك ع دد غی ر منت ھ لذلك استخدمت طریقة الشبكھ العص بیھ , (conventional methods) باستخدام الطرق التقلیدیھ ) (redundant armمطولة (neural network technique) إلیجاد حل واحد مرغوب بھ)one desired solution (من ھذه الحلول . inverse kinematics(إلیج اد الحل ول العكس یة (dnnm) مزدوج ة حی ث اس تخدم ف ي ھ ذه البح ث ش بكھ عص بیھ solutions ( ل ذراع تتك ون م ن ثالث ة قط ع تتح رك جمیعھ ا ف ي س طح واح د)three links redundant planar robot .( إن لمرحل ة الت دریب مزالمستخدمة ف ي ھ ذا العم ل أظھ رت كف اءة عالی ة ف ي تقلی ل الوق ت ال ال (dnnm)ألشبكھ العصبیة المزدوجة )training .( ق د (dnnm)ألش بكھ العص بیة المزدوج ة outputs)(عل ى مخ ارج training sets) (إن تأثیر عدد مجموعات التدریب ق د تزی د عن دما یض اعف end effector) (و أظھرت النتائج بأن الدقة في إیج اد موق ع نھای ة ال ذراع , تم دراستھا في ھذا العمل . training sets) (مجموعات التدریب عدد ق د ت م دراس تھا ف ي ھ ذا العم ل point-to-point trajectory planning method)(إن طریقة إیجاد المسار بین نقطت ین . على الدقةtraining sets) (كذلك تم دراسة تأثیر تغیر عدد مجموعات التدریب al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 5, no. 2, pp 66-71 (2009) analytical modeling of stresses in the wall 0f the human heart a. m. bayoumi* aziz al alawi** *biomedical engineering/ university of south caroline/ usa **biomedical engineering department/ alkhawarizmy college of engineering/ university of baghdad 1. (received 29 november 2008; accepted 13 july 2009) abstract the mechanical function of the heart is governed by the contractile properties of the cells, the mechanical stiffness of the muscle and connective tissue, and pressure and volume loading conditions on the organ. although ventricular pressures and volumes are available for assessing the global pumping performance of the heart, the distribution of stress and strain that characterize regional ventricular function and change in cell biology must be known. the mechanics of the equatorial region of the left, ventricle was modeled by a thick-walled cylinder. the tangential (circumferential) stress, radial stress and longitudinal stress in the wall of the heart have been calculated. there are also significant torsional shear in the wall during both systole and diastole. in addition there should exist shear stress in the wall of the heart due to action of pressure on the curved surface. keyword: stresses, human heart, mechanical function 1. introduction the heart is a powerful muscle that pumps blood throughout the body by means of coordinated contraction. this powerful muscle is slightly larger than a clenched fist. the primary function of the heart is fundamentally mechanical to pump oxygen-rich blood through all parts of the body. a human heart beats at an average of 100,000 times per day. during that time, it pumps more than 17000 liter of blood throughout the entire body, compensating for acute changes in demand for blood flow and adapting to sustained changes in the applied loads. the mammalian heart consists of four pumping champers, the right and left atria and right and left ventricles [1, 2]. 2. the walls of the heart the ventricular walls are the most important structures with regard to the pumping action of the heart. generally the wall of the heart consists of three distinct layers. a) an inner layer called the endocardium. this layer lines the inside of each cardiac chamber. it is a thin serous membrane. b) a middle layer called myocardium. it is the functional tissue that endows the heart with its ability to pump, blood. the myocardium consists primarily of myocytes that are arranged into local parallel muscle fibers, which in turn are embedded in an extra cellular matrix consisting largely of types i and iii collagen. the orientation of the muscle fibers change with position in the wall. c) the outer most layer or epicardium is also a thin serous layer consisting largely of a two dimensional plexus of collagen and some elastic fibers [3]. the pericardium is a sac-like membranous structure that surrounds the heart. it holds the heart in a fixed geometric position and isolates the heart from other structures in the thorax, to prevent adhesions and the spread of infection [4, 5]. 3. geometry the basics of the model of the left ventricular mechanics have been described in details in references [6, 7]. briefly, the left ventricle is a. m. bayoumi al-khwarizmi engineering journal, vol. 5 , no. 2, pp 66 -71 (2009) 67 l l r r represented by a thick-walled three dimensional pressure vessel whose thickness and curvature vary regionally and temporally. in the normal heart, the ventricular walls are thick at the equator and the base of the left ventricle and thin at the left ventricle apex and right ventricular free wall. nonetheless, the ratio of wall thickness to radius is always that the heart can only be treated accurately by the most sophisticated theories for thick-walled cylinder [3, 8, 9]. because of similarity of geometry the equatorial region of the ventricle is simulated most accurately. 4. stress in left ventricular wall the left ventricular can probably be described as a prolated spheroid, noting that the equatorial region can be well approximated as a thick walled cylinder [3]. moreover, a cylindrical geometry admits reasonable simple descriptions of rather complex motion radial inflation, axial extension, torsion and transmular shear; all of which have been measured in the beating and arrested heart [3]. figure (1), designates the inside radius of the annul by (a) and the outside radius (b), the internal pressure by (pi) and the external pressure by (po). then it can be shown that tangential (σt) and radial (σr) stresses exist and whose magnitude is [21]: …(1) …(2) in the above equations, positive stresses indicate tension and negative stresses indicate compressive stresses. fig. 1. a cylinder subjected to internal and external pressure (21).     222 22 22 22 rab ppba ab bpap oioi t           222 22 22 22 rab ppba ab bpap oioi t       a. m. bayoumi al-khwarizmi engineering journal, vol. 5 , no. 2, pp 66 -71 (2009) 68 in normal heart, is small and can be neglected [3], so that: …(3) …(4) the distribution of stresses across the wall thickness is non-uniformly as shown in fig (2). the tangential stress σt is tensile while the radial stress is compressive diminishing from pi at the inside surface to zero at the outside surface. from the distribution diagrams, the maximum stresses occur at the inner surface where r=a and their magnitudes are [21]: …(5) …(6) fig. .2. distribution of stresses in a thick-walled cylinder subjected to internal pressure only [21]. since the internal pressure is taken by the heart, longitudinal stresses will exist of the magnitude will exist [21], …(7) the above mentioned relations are classic relations that are derived in introductory mechanics of material courses. the results are good for cylinder subjected to a uniform inflated pressure . not restricted to particular class of material, they are examples of universal results which are particularly important in biomechanics [3]. there are also significant shear stresses in the wall during both systole and diastole (fig 3). plane (torsional) shears are negative during diastole, and are consistent with a small left-handed torsion of a. m. bayoumi al-khwarizmi engineering journal, vol. 5 , no. 2, pp 66 -71 (2009) 69 1 m the left ventricle during filling, and positive as the twist of the ventricles reverses during ejection[10]. the distribution of this stress along any radius varies linearly with the radial distance from the axis of the heart. in addition because myocardial fibers are wrapped toroidally around the central layers of the wall in the real left ventricle, [11, 12, 13], shear stress should also exist in the wall of the heart throughout the cardiac cycle, due to the action of a pressure on the curved surface. fig. 3. free body diagram of the left ventricle, showing of the longitudinal stress and the torsional moment (  is the shear stress, m is the torsional moment). 5. discussion of the results 1. the elastic circular hydraulic system of the heart causes simple harmonic motion repeated about 75 times per minute. due to this motion stress is induced in the wall of the heart with its maximum at the inside surface of the wall. since the stresses vary in magnitude and direction, in each cycle, the inside surface of the heart will be sensitive to any natural defect in the wall and that may lead to fracture in the inside surface of the wall. 2. in calculating the stresses, simplified assumptions such as homogeneous wall has been used [3]. finding by novak etal [14], kang etal [15] and hunten etal [16] suggest that the myocardium is not homogeneous, and that the endocardium and epicardium also exhibit distinct behavior [17, 18]. viewed in this manner our results must thus be considered to reflect homogenized or mean properties which can be sufficient in some analyses, but certainly not in all. 3. minor [19] noted “each heart beat or cardiac cycle is an intricate sequence of electrical and mechanical events”. although a full understanding of cardiac function will thus require an electromechanical analysis [10, 19, 20]. here it has been focused on the mechanical alone (due to limited time). 4. to avoid any assumption that can more or less affect the result of analytical modeling, experimental test should be carried out. unfortunately no experiment in laboratory is comprehensive because of the loss of the in vivo environment which includes hormonal influences and control by the nervous system on the function and properties of the cells, tissues or organ. again in vivo experiments or test, intact organs are not without concern. from the mechanics and biology points of views the intact organ is typically so complicated that the interpretation of data often requires many simplified assumptions, which in turn may musk salient features of the behavior of manifestation of many contributors that are often difficult to delineate. therefore, we must consider many different classes of test with the hope that together they will reveal most of the feature of interest [3]. a. m. bayoumi al-khwarizmi engineering journal, vol. 5 , no. 2, pp 66 -71 (2009) 70 6. conclusion the left ventricle is represented by thick walled three dimensional pressure vessels. due to the complex motions of the ventricle, radial inflation, axial extension, torsion and transmular shear. stresses are induced in the wall of the ventricles. 1. tangential and radial stresses exist. the distribution of these stresses across the wall thickness is non-uniformly. 2. since the internal pressure is taken by the heart longitudinal stress will exist. 3. there are also significant shear stresses in the wall during both systole and diastole. they are negative during diastole when filling and positive as the twist of the ventricles reverses during ejection. 4. in addition, because myocardial fibers are rapped toroidally around the central layers of the wall in the real left ventricle, shear stress should also exist in the wall of the heart throughout the cardiac cycle, due to action of a pressure on the curved surface. since all these mentioned stresses vary in magnitude or and direction in each cycle, the inside surface of the heart will be sensitive to any natural defect in the wall and this may leading to fracture inside the wall. 7. references [1] elizabeth m. cherry and flavio h. fenton "heart structure function and arrhythmias" department of biomedical college of verterinary medicine, corneu university, ithaca ny. [2] dr. robert m. anderson "the gross physiology of the cardiovascular system" spriger verlag. [3] jay d. humphery "cardiovascular solid mechanics, cell, tissues and organs" springer verlag. [4] half jp (1970) "the normal pericardium". am. j. cardiol 26: 455-463. [5] spodicks dh (1970) medical history of the pericardium: the hairy hearts of hoary heroes. am. j. cardiol 26: 447-454. [6] arts t, p.c. veenstra, and r.s. reneman. (1979) a model of mechanics of the left ventricle. ann biomed eng 7:299 [7] arts t., and r.s. reneman. (1989) dynamic of left ventricular wall and mitral valve mechanics. j. biomechanics 22:216:291. [8] arts t. etal (1994) adaptation of cardiac structure by mechanical feedback in the environment of cell: a model study biophysical journal volume 66 april 1994 953-961. [9] taber l.a. (1991) on nonlinear theory of muscle shells: application to the beating left ventricle. asme j. biomed. eng.113:63. [10] tozeren a. (1983) static analysis of the left ventricle. asme j. biomed. eng. 105:3946. [11] chadwick r.s. (1982) mechanics of the left ventricle. biophys. j. 39:279-288. [12] peskin, c.s. (1989) fiber architecture of the left ventricular wall: an asymptotic analysis. pure appl. math 42:79-113. [13] waldman, l.k., y.c. fung and j.w. covell. (1985) transmural myocardial deformation in the canine left ventricle. normal in vivo three-dimension finite strain circ. aes. 57: 152-163. [14] novak vp., fcp yin, j.d. humphrey (1994) regional mechanical properties of passive myocardium. j. biomech. 27:403-412. [15] kang t., j.d.humphrey, fcp.yin(1996). comparison of the biaxial mechanical properties of excised endocardium and epicardium. am. j. physiol 270:h2169h2176. [16] hunter ps,mp nash, gb sands (1997a) computational electromechanics of the heart. in: computational biology of the heart john wiely, london. [17] smith n.p., p.j. mulquiney, m.p. nash (2002) _haos, solutions and fractal 13:1613-1621. [18] kheradvar a., m. milano, r.c. gorman (2006). cardiovascular eng.: an international journal, vol. 6 no. 1 31-40. [19] minor w.r. (1990). cardiovascular physiology oxford university press, oxford. [20] panfilor a.v., a.v. holden (1997). computation biology of the heart. john wiley london. [21] joseph e. shiyley (2004). mechanical engineering design. mc graw hill. 71 66، صفحة 2، العذد 5 مجلة الخوارزمي الهنذسية المجلذعبذ المعتز بيومي (2009) 71 نمورج تحليل اإلجهادات داخل قلب اإلنسان ** عزيز العلوي* عبذ المعتز بيومي انىالياخ انمتحذج االمزيكيح / جامعح كارواليىا انجىىتيح/ هىذسح انطة انحياتي * جامعح تغذاد / كهيح هىذسح انخىارسمي/ قسم هىذسح انطة انحياتي** الخالصة انحزكح انميكاويكيح نهقهة، مسيطزج تانخاصياخ انتقهصيح نهخاليا، انصالدج انميكاويكيح نهعضالخ وانىسيج انزاتط وضغط وحجم انحمم عهى انتي تىصف ( strain, stress)انعضى تانزغم مه ان ضغط وحجم انثطيه متىفزج نتقييم اداء انذفع انكهي نهقهة، نكه تىسيع انجهذ وانتىتز . وظيفح انثطيه مىضىعيا وانتغيز في حيىيح انخهيح يجة ان تعزف ان ميكىيكيح انمىطقح انقهثيح نهثطيه تمثم تاالسطىاوح انسميكح انجذران وعهى هذي انفزضيح تم حساب انجهذ انمحيطي وانجهذ نشعاعي وجهذ في shear stress في انجذار اضافح وجىد جهذ قص torsion stressخالل تقهص واوقثاض انقهة يتكىن جهذ ني . انطىل في جذار انقهة . في انثطيهجذار نقهة نعمم انضغط عهى االسطح انمقىس view al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 6, no. 3, pp 36 44 (2010) guiding mobile robot by applying fuzzy approach on sonar sensors nabeel k. abid alsahib* ahmed rahman jasim** department of mechatronics engineering/ al–khwarizmi college of engineering/ university of baghdad * email: dr_nabeelalsahab@hotmail.com ** email: engmktron@gmail.com (received 4 june 2009; accepted 10 august 2010) abstract this study describes how fuzzy logic control flc can be applied to sonars of mobile robot. the fuzzy logic approach has effects on the navigation of mobile robots in a partially known environment that are used in different industrial and society applications. the fuzzy logic provides a mechanism for combining sensor data from all sonar sensors which present different information. the flc approach is achieved by means of fuzzy decision making method type of fuzzy logic controller. the proposed controller is responsible for the obstacle avoidance of the mobile robot while traveling through a map from a home point to a goal point. the flc is built as a subprogram based on the intelligent architecture (ia). the software program uses the advanced robotics interface for applications (aria), it is programmed with c++ package ( visual c++.net ), and networking software is used for setup wireless tcp/ip ethernet-to-serial connection between robot and pc. the results show that the developed mobile robot travels successfully from one location to another and reaches its goal after avoiding all obstacles that are located in its way. the platform mobile robot is a pioneer 3 dx that is equipped with sonar sensors. keywords: flc, mobile robot, sonar sensors, navigation, fuzzy decision making method, obstacle avoidance, intelligent architecture. 1. introduction one of the main objectives of mobile robotics is the construction of autonomous systems that are capable of moving in real environments without the help of a human operator. there are numerous difficulties in the attainment of this objective, due principally to the fact that real environments are, generally, uncertain, unknown and dynamic. thus, the knowledge which is available a priori on these environments may be non-existent, incomplete, uncertain or imprecise, or the environments may undergo modifications over time, which renders them more complex and unpredictable [1]. pioneer 3 dx is a mobile robot which has sonar sensors, [2]. the data from sonar sensors is the distance between the sonar and object. the sonar sensor arrangement for mobile robot is shown in figure 1. fig. 1. the sonar arrangement for p3dx. the sonar sensors locations are important for designing the fuzzy controller. the application of fuzzy control to obstacle avoidance has been implemented for pioneer robot. all sonar sensors send data to the inputs of fuzzy controllers. each fuzzy controller for obstacle avoidance has two this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ nabeel k. abid alsahib al-khwarizmi engineering journal, vol. 6, no. 3, pp 36 44 (2010) 37 inputs and two outputs. inputs have membership functions. each membership function is considered as a triangle function. in this paper, the fuzzy controller for the oriention of a robot is described. all fuzzy controllers are implemented under the fuzzy decision making approach. fuzzy decision making approaches have been established as a main alternative to conventional robot control in recent years [3]. the system architecture, implemented in the ia in this application, has two objectives. the first one is the obstacle avoidance and the second one is the orientation behavior. 2. navigation the navigation of a mobile vehicle can be considered as a task of determining a collision free path that enables the vehicle to travel through an obstacle course from an initial configuration to a goal configuration [4]. 3. obstacle avoidance the obstacle avoidance algorithm is based on the relative angle and distance between a robot and other objects; each time the robot calculates the relative angle and distance by sensor of robots. autonomous mobile robot has sensors and the robot calculates the relative angle and distance. these calculative values are important factors of algorithm [5]. 4. fuzzy control fuzzy logic control is selected as it is easiest to implement for a highly nonlinear robot model. although a relatively new concept, fuzzy logic is being used in many engineering applications because it is considered by designers to be the simplest solution available for the specific problem[6]. fuzzy decision making fdm is a useful method of fuzzy control theory to implement different behavior of work. within fdm, it may form the basis for the implementation of behaviors as modular building blocks for complex control by using the techniques of fuzzy control. the concepts of fuzzy decision making theory found wide application in various areas such as robotics path planning, navigation and mission planning, it has the potential to benefit from the application of fuzzy logic to provide for soft decisions when there is the need for decision making under uncertainty[3]. the advantage of fuzzy logic control is that it enables control engineers to easily implement control strategies which can be used by a human operator. [7]. there are three steps for designing a fuzzy controller: fuzzifcation, inference engine, and defuzzifcation. 4.1 fuzzification fuzzification is defined as the mapping from a real-valued point to a fuzzy set. in most fuzzy decision systems, non fuzzy input data is mapped to fuzzy sets by treating them as singleton membership functions, gaussian membership functions, triangular membership functions, etc. 4.2 inference engine fuzzy inference engine is used to combine the fuzzy if-then in the fuzzy rule-base, and to convert input information into output membership functions. an inference mechanism emulates the expert's decision-making in interpreting and applying knowledge about how to perform good control. the fuzzy inference rules are based on reasoning similar to that of a human driver [8]. this can be implemented as a fuzzy rule-base. the rules may use the experts experience and control engineering knowledge. there are three types of fuzzy rule-based models for function approximation: mamdani model, takagi-sugenokang model, and kosko's additive model. 4.3 defuzzification there are many methods which can be used for converting the conclusions of the inference mechanism into the actual input for the process or for the plant. center of gravity (cog) defuzzification method is defined as equation (1). …(1) where : y= controller output, n= the number of rules, μa(yi): member ship function of fuzzy set a calculated for the input variables, yi : the center of area of of fuzzy set ai of i-th of the rule, other defuzzification techniques, are centeraverage defuzzification, maximum defuzzification, etc. [3]. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ nabeel k. abid alsahib al-khwarizmi engineering journal, vol. 6, no. 3, pp 36 44 (2010) 38 5. obstacle avoidance design the fuzzy controllers for obstacle avoidance are designed as follows: first read sonar data and construct three membership functions for input. all data from sonar sensors are received and displayed. three membership functions for each input in its universe are constructed. each membership function is considered as a triangle membership function. the rules for avoiding frontal obstacles are developed in many stages. the sonar notations are the same as shown in figure (2) for convenience. the rule base of each table depends on the sensor arrangement. a fuzzy controller can be designed as follows: the input membership functions represent the right and left side readings of distance from the object ,if observed, in path by signal from sonar sensors, avoid object on right side (aor) and avoid object on left side ( aol). fig.2. sonar range notation for robot. the membership function is a three triangular membership function representing robot conditions that are good, near and far from the object lines. fig.3. avoidance input membership function. table (1) shows the relation between linguistic input and ranges. the near and far membership functions overlap the good membership function, so that the distance can be both good, and near the object line, or both good and far from the line, this overlap in the membership functions allows application of multiple rules in this region. this membership functions are used for right sensors and left sensors inputs. table 1, linguistic input fuzzy set and their ranges. sonar distance (ao)ranges linguistic variable notation range in meter near ne [0.00,0.45] good go [0.25,0.75] far fa [0.55, 1.0 ] 6. orientation control design the direction angle membership function is a 5triangular membership functions, representing angle conditions that are very negative, negative, zero, positive, and very positive. the objective of the orientation is to keep the robot pointing toward a given target so that progress is made. if the robot has to travel from a known present location (xrobot , yrobot ) to a goal (xgoal,ygoal ); then the following procedure is performed. goalrobot xxδx  …(2) goalrobot yyδy  …(3) figure (4 ) represents the robot orientation with goal with orientation respect to global map. fig.4. robot orientation with respect to the goal. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ nabeel k. abid alsahib al-khwarizmi engineering journal, vol. 6, no. 3, pp 36 44 (2010) 39  : the angle formed between the robot center and the x-axis. α : the angle formed between the goal center and the x-axis. figure (5) represents the direction membership function. fig.5. direction membership function. the output direction angle membership function is a 5-triangular membership functions, representing output angle conditions that are: big left, left, zero, big right and right. figure (6) represents direction output membership function. fig.6. direction output membership function. the fundamental principle of all of the controller logic is to bring the robot in the path, which means defining a start point and the goal. the path is drawn to the robot by programming a fuzzy logic system into the controller code. this information is used to select the robot angular velocity (vr) and output direction by rule base statements, as follows: rule base statements if (dir = p) and (aor = ne) and (aol = far) then (vr= sf) and (dirr=l) if (dir = vp) and (aor = ne) and (aol = far) then (vr= s) and (dirr=l) if (dir = vn) and (aor = go) and (aol = far) then (vr= sf) and (dirr=bl) if (dir = n) and (aor = go) and (aol = far) then (vr= sf) and (dirr=l) if (dir = z) and (aor = go) and (aol = far) then (vr= f) and (dirr=ze) if (dir = p) and (aor = go) and (aol = far) then (vr= sf) and (dirr=r for output variables: f: forward sf: slow forward s: stop sb: slow backward b: backward bl: big left l: left r: right br: big right ze: zero in the step of defuzzification , the membership function for the control action of angular velocity is defuzzified by using the centroid method.. finally, the output for angular velocity is given by equation (1). 7. robot description the platform used in work is pioneer3 dx which is a family of two wheel mobile robots. the robot has reversible dc motors, motor-control driver, high-resolution motion encoders, and battery power; all are managed by an onboard microcontroller and mobile-robot server software as shown in figure (7). the software includes foundation advanced robotics interface for applications (aria) and advanced robot for arnetworking . fig.7. pioneer platform. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ nabeel k. abid alsahib al-khwarizmi engineering journal, vol. 6, no. 3, pp 36 44 (2010) 40 the mobile robot platforms require a pc connection: software running on a computer connected with the robot’s microcontroller via the host serial link and which provides a high-level mobile robot software, intelligent robot controls, advanced robotics interface for applications (aria) software and arnetworking. aria is a c++ based open-source development environment that provides a robust client-side interface to a variety of intelligent robotics systems, including the robot’s microcontroller and accessory systems. arnetworking software provides the critical layer for communication with mobile robot platform over the network via transmission control protocol/internet protocol (tcp/ip), the tcp/ip is the most popular network protocol, and the basis for the internet. its routing capabilities provide maximum flexibility in an enterprise-wide network. on a tcp/ip network, ip must provide addresses to clients. clients may also require a naming service . 8. wireless ethernet-to-serial connection wireless ethernet to serial is a little more complicated, but is the preferred method because it can use many different computers on the network to become the robot’s client so allowing greater degrees of flexibility and interoperability between mobile devices [9]. fig.8. client-server connection. a wireless ethernet-to-serial connects directly to robot’s microcontroller, it works by automatically translating network-based ethernet packet communications tcp/ip into streaming serial for the robot microcontroller and back again. a major disadvantage of the wireless ethernet-to-serial device is that it requires a consistent wireless connection with the robot; disruption of the radio signal a common occurrence in even the most modern installation leads to poor robot performance and to very short ranges of operation. secure connection is important to save robot from undesirable connection. figure(8) shows client-server connection. 9. software program the programmer usually includes idea along the path at space intersections or other choice points which the robot should achieve as quickly as possible, taking into consideration safety and power. and as the robot work to achieve those larger goals, it should avoid obstacles and respond to accident, such as closed doors or blocked way, go-to-goal is defined for path. it is a value of directed difference to the nearest goal with respect to current robot position. figure (9) shows the flowchart of the program, a crisp value for aol, aor,dirc and dirr input to program; then they are fuzzified to linguistic variables such as “ object near left sonar “, in program inference system list the rule base statments like “ if dir = positive and aor = negative then robot angle is positive”. by defuzzifying these values, it puts crisp output parameters like “ robot angle = +30” send to robot platform. fig. 9. the flowchart of the program. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ nabeel k. abid alsahib al-khwarizmi engineering journal, vol. 6, no. 3, pp 36 44 (2010) 41 10. obstacle avoidance and orientation behavior the obstacle avoidance behavior uses sonar sensor data to generate a fuzzy set that represents the distance relating to robot location. the behavior is operated by using the fuzzy controller. the fuzzy inputs are the fuzzy sets from front,left and right. the sensors on the front-left and the sensors on the front right are used for obstacle avoidance behavior. therefore, the fuzzy controllers are required in this behavior. the output is the avoiding rotation. the results of obstacle avoidance behavior will be shown in the following cases. go–to-goal program is a task effect on orientation behaviors. 11. case study cases are based on building’s map in which some fixed elements of the environment are located with known positions: walls, doors, furniture, etc. but unfixed elements, whose positions are unknown, can be added to the environment. 11.1. one wall map without obstacle map drawn with dimension 3m y axis and 5m x axis ,home point = (0.0, 0.0) and goal position = (-4.0, 0.0) while wall = 75cm long , 10cm width ,on 2.5m left from home is shown in figure(10). fig.10. robot behavior on one wall environment. an obstacle is added to the environment of the last map. the obstacle is located = (-1.5, -1)m from home. when the obstacle is detected near the robot, flc turns the orientation of the robot right until the robot escapes from the obstacle after the robot crosses its the obstacle; then it tries to return back to the last path and move toward goal, as shown in figure(11). fig.(11) obstacle added to environment 11.2. three obstacles environment a (5,3)m map, robot started with position (0,0); then the robot tried to take straight path but observing the obstacles induces the robot to turn left. after crossing the obstacle, the robot turns right straightly to the goal, as shown in figure (12). fig.12. robot behavior in three obstacles. 12. results the result will be represented in a graph, where vertical left axis represents robot velocity (cm/sec) through the map, the right vertical axis represents the angle (degree) of robot , and horizontal axis represent the time (sec.) of case . in case (1), one wall map without obstacle : figure (13) shows the relation between robot velocity , angle and time. the velocity of robot decreased at point (a) when robot try to avoid wall and turned right at point (b) , with straight open area motion in point (d) velocity increases at point (c) , after avoiding the wall ; the robot tried to reach goal and turn left in point (e) in the this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ nabeel k. abid alsahib al-khwarizmi engineering journal, vol. 6, no. 3, pp 36 44 (2010) 42 end when the robot reached near the goal, velocity was decreased to zero and got goal orientation in point (f). fig.13. navigation without obstacles. case (2): when an obstacle was added to the environment at the path of last map, the robot primary turned right at point (a). that caused reducing the velocity shown in figure (14) in point (b). the next points (c) and (d) represent a turn of robot to the left when it observed an obstacle and then returned to the save path of motion as shown in figure (13). fig.14. navigation with obstacles. so a safe navigation of motion with a full known environment is approved in case1, and a safe navigation of motion with a partial known environment is approved in case 2. 13. conclusions studying mobile robot control by flc leads to many conclusions, as follows: 1the differential mobile robot includes many kinematics constraint, which can’t be reduced at one equivalent constraint of configuration variables, so that using the methods which avoid the analytical modeling problem, such as fuzzy control methods, and neural network control. 2the navigation system used by the robot is based on two receivers, robot current position and goal . 3the robot movement in case of flc programming improves the robot navigation by avoiding damag itself. 4a decision making program is constructed for the local-path planning. it is not necessary to define a reference point prior to home. 5for obstacle avoidance, two types of execution panels are carried; one with landmarks and the other with objects. the latter is used to generate complex environments for the mobile robot to its ability to avoid obstacles. the obstacle avoidance success by using fuzzy rules. 6the effect of varying sensor range showed that it does not only affect the distance between the mobile robot, obstacles and walls, but also affects the shape of the path to the goal. 14. references [1] m. mucientesa, r. iglesiasa, c.v. regueirob, a. bugar-.na, s. barroa, ''a fuzzy temporal rule-based velocity controller for mobile robotics'', fuzzy sets and systems, vol. 134, pp. 83–99, 2003. [2] pioneer reference book, www.mobilerobotics. com. 2008. [3] kevin m. passino, stephen yurkovich, ''fuzzy control'', addition wesley longman,inc., california, 1998. [4] hani hagras, victor callaghan, martin colley, ''learning and adaptation of an intelligent mobile robot navigator operating in unstructured environment based on a novel online fuzzy–genetic system'', fuzzy sets and systems, vol. 141, pp.107–160, 2004. [5] jang hyun kim1, jin bae park2, and hyunseok yang, ''implementation of the avoidance algorithm for autonomous mobile robots using fuzzy rules'', lnai, vol. 4223, pp. 836–845, 2006. [6] vamsi mohan, dan simonm, ''fuzzy logic control for an autonomous robot'', 2004. [7] rerngwut choomuang , nitin afzulpurkar , '' hybrid kalman filter/fuzzy logic based position control of autonomous mobile this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ nabeel k. abid alsahib al-khwarizmi engineering journal, vol. 6, no. 3, pp 36 44 (2010) 43 robot'', international journal of advanced robotic systems, vol. 2, pp. 197 208, 2005. [8] elie maaloufa, maarouf saada, ''a higher level path tracking controller for a four-wheel differentially steered mobile robot'', robotics and autonomous systems, vol.54, pp. 23–33, october, 2005. [9] k.a.hawick and h.a.james, ''middleware for wireless sensors and robots'', technical dhpc-112, 2002. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ )2010( 44 -36 ، صفحة3، العدد 6ة المجلد مجلة الخوارزمي الھندسی نبیل كاظم عبد الصاحب 44 ّسساِت السوناِرتِة الضبابیِة على محیاآللي النقَّال بَتطبیق النظراالنسان َتوجیھ **احمد رحمان جاسم *نبیل كاظم عبد الصاحب جامعة بغداد / ھندسة الخوارزميلاكلیة / قسم ھندسة المیكاترونكس dr_nabeelalsahab@hotmail.com: البرید االلكتروني* engmktron@gmail.com: البرید االلكتروني** الخالصة ة ُتؤثر نظریُة الم. اِلِصُف ھذه الدراسِة َكیفیة سیطرة المنطِق الضبابي إلى سوناِر اإلنسان اآللي النقََّت ي بیئ اِل ف نطِق الضبابیِة على مالحة اإلنسان اآللي النقَّ ّدُم . معروفة جزئیًا التي تستعمل في مختلفِة الصناعات وتطبیقاِت المجتمِع ي ُتق وناِر الت ات الس ّل محّسس ْن ُك ِس ِم المنطق الضبابي ُیزّوُد آلیة لَدْمج بیاناِت المحّس بابيِ ُمنَج flcإّن نظریَة . المعلوماَت المختلفَة ؤول . زُة بواسطة طریقِة إّتخاذ القراراِت الضبابِیة ِمْن جھاِز سیطرة المنطِق الض َرَح مس یطرة الُمقَت اَز الس إّن جھ ة الم flc. عن تجّنِب عقبات اإلنسان اآللي النقَّاِل بتنقلھ خالل خریطة ِمْن نقطة المرجع إلى نقطة الھدِف ى الھندس تند عل ِة ُیْبَنى برامج ثانویة مس ِة الذكی عماری )aa .( اِت ة ) aria(َیستعمُل برنامُج اإلنسان اآللي المتقّدمِة للتطبیق رمج بلغ وع c++المب رامج )ِ visual c++.net(ن بكات ال ، وب ام الش تعملُة لنظ مس داِد لكي اإلع اِل الالس ى االرس بة / السیطرة عل ي والحاس ان اآلل ین اإلنس ِل ب اِل المتسلس ى اإلّتص ت إل یة إیثرن اَل . الشخص ي النقَّ ان اآلل أّن اإلنس اِئَج ب ر الَنت ُتظھ ھ ي طریِق ة ف ات الواقع و . المتطوَر ُیتنقُل بنجاح من موقع إلى آخر ویصُل ھدَفھ بعد َتفادي ُكّل العقب اَل ھ ي النقَّ ان آالل ل اإلنس ز pioneer 3 dxإّن ھیك الُمجّھ .بمحّسساِت السوناِر this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 4, no. 2, pp 19 (2008) hydrodynamics, mass and heat transfer in reactive distillation dr. majid s. radhaa, dr. khalid a. sukkar * , dr. jamal m. ali, dr. zaidoon m. shakoor, and niran manwel *department of chemical engineering, university of technology, baghdad, iraq (received 17 septemper 2007; accepted 13 february 2008) abstract the ethyl acetate synthesis via heterogeneous reactive distillation is studied experimentally using ethanol and acetic acid. three types of cation exchanging resins were used as catalysts: zerolit 225, zerolit 226 and ambylite 400. experiments were carried out in two units of the same dimensions. each unit consisted of three sections: rectifying, reactive and stripping sections of heights (60+25+20) cm respectively and 2.5cm column diameter. the first unit (column-a-) was a fractionation type and the second unit (column-b-) was packed column. the packing type was hollow glass cylinders with 10 mm height, and 4, 5 mm inner and outer diameter respectively. the experiments were carried out by using two operation modes. the semi-batch and continuous operation mode. in the first part of present investigation, the semi-batch mode was used to evaluate the catalyst type and to evaluate the performance of reactive distillation unit configuration (fractionation and packed column). results show that, the column-bgave higher conversion rates than column-a-. this is attributed to the high surface area available for liquid vapour contact in packed type column, which leads to increasing mass transfer rates. on the other hand, ambylite 400 catalyst showed higher activity for esterification reaction than other two types of catalysts. the second part of work continued with column -bonly. it is well known that, the esterification process is regarded one of exothermic reactions. therefore, the monitoring of the temperature distribution along column axial for all three types of catalysts showed that the temperature distribution was essentially the same due to steady state operation in continuous operation mode. on the other hand, the effect of reflux ratio on temperature distribution was clearly noted, that is as the reflux ratio increased the temperature distribution along the column was reduced for each type of catalysts. on the other hand, the experimental results point that, as a reflux ratio increases the conversion rates of acetic acid is increased too because such increasing is related to high mass transfer rates between vapour and liquid along reactive distillation column. keywords: reactive distillation; esterification; ethyl acetate; heterogeneous catalysts. introduction the combination of chemical reaction with distillation in only one unit is called reactive distillation [1]. the performance of reaction with separation in one piece of equipment offers distinct advantages over the conventional, sequential approach. especially for equilibrium limited reactions such as etherification, esterification and ester hydrolysis reactions, conversion can be increased far beyond chemical equilibrium conversion due to the continuous removal of reaction products from the reactive zone. this may lead to an enormous reduction of capital and investment costs and may be important for sustainable development due to a lower consumption of resources. therefore, the main advantages of reactive distillation equipment can be summarized as follows [2, 3]: higher conversion, selectivity and yield avoid equilibrium restrictions removal of side reactions removal of recycling streams avoidance of non-reactive azeotropes reduction of number of units (investment cost) reduction of energy demands (heat integration). figure (1) shows the general construction of reactive distillation unit, which includes three khalid a. sukkar al-khwarizmi engineering journal, vol. 4, no. 2, pp 1-9 (2008) 2 main sections named rectifying, reactive and stripping sections [2]. esters are an important class of chemicals, having applications in a variety of areas such as solvents, plasticizers, pharmaceuticals and intermediates. among them, ethyl acetate (etac) is an important organic solvent widely used in the production of varnishes, ink, synthetic resins, and adhesive agents. this ester is typically produced from the reaction of acetic acid (hac) and ethanol (etoh) [4,5]. fig. 1. general construction of reactive distillation. both homogenous and heterogeneous catalysts could be used in reactive distillation column to produce etac. sulfuric acid is generally used in homogenous catalysis. heterogeneously catalyzed reactions involve the use of acidic polymeric catalysts such as ion exchange resins. however, the use of heterogeneous catalysts has become more common in recent times because of its significant advantages over homogenous catalyst. the use of heterogeneous catalyst allows for easy and inexpensive product removal from reaction mixture by filtration or centrifugation. moreover, heterogeneous catalyst can withstand a wider range of temperatures and pressures [1, 5]. the overall reaction between acetic acid and ethyl alcohol over a catalytically active resin is as follows: this reaction is reversible, and the equilibrium composition is a weak function of temperature. the reaction is acid catalyzed by using the cation exchange resins catalysts [2, 3, 5]. tang et al. [6] studied the process which contains sulfuric acid as catalyst (homogeneous reaction) using an reactive distillation column with an overhead decanter and a stripping column. highly pure etac product was obtained and all the outlet streams met product and environmental specifications. tang et al. [7] provide generalization for the study of design of reactive distillation with acetic acid as one feed. chang and seider [8] concluded that a continuous reactive distillation column cannot produce pure ethyl acetate at the top due to the ternary minimum boiling azeotrope of ethyl acetate, ethanol and water, which prevents a desired overall reaction conversion. bock et al. [9] propose a different configuration of a reactive distillation column followed by a nonreactive recovery column to produce pure ethyl acetate under excess reactants. research in catalysis by ion exchange resins is undoubtedly interesting, not only from a purely physicochemical point of view but also in terms of the advantages of these types of catalyst over the conventional ones. ion exchange resins increase the product yield, keep their activity a long time, and do not pollute. ion exchange resins separate from reaction media easily and they regenerate easily for reuse in chemical processes [10,11, 12, 13]. however, there is a limited work in literature about the performance of reactive distillation column that uses heterogeneous catalysts. on the other hand, the design, operation and optimization of reactive distillation require the knowledge of the hydrodynamics, mass as well as heat transfer characteristics and their interactions. therefore, due to the complex interactions between chemical reaction, heat, and mass transfer, the present work aims to study the performance of reactive distillation column in esterification reaction to produce ethyl acetate by using heterogeneous catalysts. experimenral work figure (2) shows a view of the experimental apparatus, while, figure (3) shows the schematic diagram of two reactive distillation experimental set-up. the first system is (column-a-) which is a fractionation type distillation column made of perspex glass. the height of the column was 105 cm (three sections: rectifying 60 cm, reactive 25 cm, and stripping 20 cm) and 2.5cm column khalid a. sukkar al-khwarizmi engineering journal, vol. 4, no. 2, pp 1-9 (2008) 3 diameter. on the other hand, the second column (column-b-) was packed column made of qvf glass of the same dimensions of the first column. the rectifying and stripping sections were filled with hollow cylinder glass packing (non-reactive packing of 10 mm height, and 4, 5 mm inner and outer diameter respectively) with voidage fraction of 0.66. the middle sections of the both columns were filled with 30 gm of the catalyst. the top of each column was connected with a condenser where a coolant (t= 20°c) was circulated to condense vapor from the reactive distillation column. the condensate was passed into a solenoid valve. a multi-timer was used as a reflux ratio controller. the bottom of each column was connected to a reboiler (2000cm 3 three neck flask). heat supply required for the reboiler was regulated by a variable transformer via adjustable voltage. the temperature along the columns axial were determined by manufacturing an interface system (computerized temperature measurement system) which have sixteen copper-constantan thermocouples (t type) (eight thermocouples for each column). this interface is programmed and run by a computer (p4), which converts the measured voltages to the corresponding temperatures with the help of appropriate software in excel program. the temperature in each section of the column was noted after starting the reaction, and steady state was achieved when the temperatures in various sections of the column were stabilized. fig. 2. general view of experimental apparatus. materials and catalysts three types of catalysts (cation exchange resins) were used in the present investigation, zerolit 225, zerolit 226, and ambylite 400 purchased from bdh. the particle sizes and the total surface area of the resins used are given in table (1). the wet catalyst was first washed with methanol to remove any water that might be sorbed in the resin catalyst. this step aided in avoiding the collapse of the resin pore structure in the subsequent drying process. then, dried under vacuum by gentle heating for 6 hours at 100°c. the prepared catalyst was stored in a desiccator in the presence of silica gel. acetic acid (99.8%) and ethanol (99.5%) were purchased from scharlau company. table (2) shows the boiling points of feed and products compounds. table 1 properties of cation exchange resins used in present investigation. catalyst average particle size dp (mm) surface area (m2/g) zerolit 225 0.65 26.2 zerolit 226 0.54 21.5 ambylite 400 1.11 34.8 table 2 boiling points of feed and products compounds. no. compound boiling point, °c 1 etoh 78.31 2 hac 118.01 3 h2o 100.0 4 etac 77.20 experimental procedure the experiments were carried out in order to achieve an optimum column configuration for the production of ethyl acetate in a reactive distillation column. therefore, two modes of reactive distillation operation were used in the present investigation: semi-batch and continuous operation mode. khalid a. sukkar al-khwarizmi engineering journal, vol. 4, no. 2, pp 1-9 (2008) 4 fig. 3. experimental units: afractionation rd, and bpacked rd system. semi-batch operation mode the semi-batch mode was used to evaluate the catalyst type and to evaluate the performance and design of reactive distillation unit configuration (fractionation column-aand packed column -b). therefore, a batch of 1000 cm 3 of etoh was used in the settle (reboiler), while the acetic acid was fed at the top of the reactive section by using dosing pump with flow rate of 5 cm 3 /min. the operation conducted under total reflux condition and atmospheric pressure. continuous operation mode the continuous operation mode was used to investigate the flowing parameters: 1the performance of catalyst type, 2reflux ratio, and 3temperature distribution along rd column. on the other hand, in continuous operation, two dosing pumps were used to feed the reactants to rd. the acetic acid was fed at the top of the reactive section, while the etoh fed at the lower part of the reactive section. therefore, for each test (17.12) mole of hac was fed to (17.12) mole of etoh (i.e the mole ratio of hac/etoh =1). the reactants were introduced into the reactive distillation column at room temperature and atmospheric pressure. the reaction was carried out until reaching steady state. top and bottom products were sampled and their concentrations were measured every 1 hr. the products were analyzed in a gas chromatograph (shimadzu gc-2014) by tcd with a capillary column (s.g.e., length = 25 mm, i.d.= 0.22 mm, film= 0.2μm). results and discussion semi-batch operation mode the design and operation of reactive distillation systems are considerably more complex than those involved in either conventional reactors or conventional distillation columns. the introduction of separation process within the reaction zone leads to complex interactions between vapour-liquid equilibrium, vapour-liquid mass transfer, intra-catalyst diffusion and chemical kinetics. from the acetic acid recovery point of view, the optimal configuration should give the highest conversion of acetic acid with a minimum concentration of acetic acid at the top, as well as a minimum concentration of ethyl acetate at the bottom. therefore, in order to evaluate the type of catalysts used in present investigation, the effect of the catalyst on the extent of conversion is presented in figures (4) and (5) for column-a khalid a. sukkar al-khwarizmi engineering journal, vol. 4, no. 2, pp 1-9 (2008) 5 and column-brespectively under semi-batch operation mode. fig. 4. influence of catalyst type on esterification of hac with etoh to etac in fractionation rd under semi-batch operation mode. the comparison between the catalyst performance of figures (5) and (6) shows that, the packed column rd (column-b-) gives higher rates of conversion of hac to etac with reaction time than that of fractionation rd (column-a-). this indicates that, the column-b provides an excellent heat and mass transfer between the liquid and vapour phases which arise from its structure of ordered flow channels. furthermore, the packings helps to promote mixing and distribution of ascending vapour and descending liquid phases in rd due to high total surface area of packing. on the other hand, the packing column leads to a better separation of products from reactants for such equilibrium limited reactions. these results are in agreement with the work of saha et al. [2] and tang et al. [6]. therefore, the second part of the present investigation will continue by using just packed column (column-b-) only with continuous operation mode, because the high surface area that was provided in such column. temperature distribution in rd esterification process is regarded one of highly exothermic reactions, therefore, benefits of heat integration are obtained because the heat generated in the chemical reactions is used for vaporization. on the other hand, the reactants and products must have suitable volatility to maintain high concentrations of reactants and low concentrations of products in the reaction zone. therefore, in esterification process the temperature distribution and liquid-vapour interaction must be known. fig. 5. influence of catalyst type on esterification of hac with etoh to etac in packed rd under semi-batch operation mode. figure (6) shows the comparison between the temperature distribution of the three types of catalysts used for esterification reaction under constant conditions of: (catalyst weight = 30g, r= 2, and hac/etoh=1). the temperature in the bottom was about 84°c. it rapidly changes around the interface of reaction and separation zones. the temperature in rectifying zone is about 77.5°c, which is the azeotropic temperature. from the same figure, it is clear that, the temperature distribution along column axial for all three types of catalysts show an increase in the region of reaction zone because the generated heat from exothermic reaction. on the other hand, the temperature distribution up to condenser is essentially the same due to steady state operation. according to table (2), the boiling points of hac and h2o are higher enough, therefore, such compounds exist in the stripping zone and reboiler. in order to study the effect of reflux ratio on the temperature distribution along the rd column, figures (7), (8), and (9) show the effect of the four levels of reflux ratio r (1, 2, 3, and 5) on the temperature distribution under constant operation conditions. for all three types of catalysts, these figures show that, there an inverse relationship between r and temperature distribution for all types of catalysts. therefore, as the reflux ratio increases the temperature distribution level along the column axial decreases. the explanation of such behavior is based on phenomenon of interaction between liquid-vapour equilibrium in reactive distillation. khalid a. sukkar al-khwarizmi engineering journal, vol. 4, no. 2, pp 1-9 (2008) 6 fig. 6. comparison of temperature distribution levels between catalyst types along rd column. fig. 7. temperature distribution along rd column using amb. 400 catalyst at different reflux ratios. fig. 8. temperature distribution along rd column using zerolit 225 catalyst at different reflux ratios. fig. 9. temperature distribution along rd column using zerolit 226 catalyst at different reflux ratios. effect of reflux ratio the effect of the reflux ratio of the organic phase (of the top product) was investigated to determine the conversion of acetic acid from its aqueous solution. the ranges of reflux ratio values reported by various investigations [1,2, 10] vary between 1 and 6. the present experiments were conducted at values of reflux ratio 0.5, 1, 2, 3, and 5. in all experimental runs, the feed mole ratio of hac to etoh was kept at the optimum ratio of 1:1. all other operating conditions were kept constant. there was an increase in acetic acid conversion from 32% to about 53-65% when the reflux ratio of the organic phase was raised from 0.5 to 5 for all types of catalysts as shown in figure (10). in other words, as the reflux ratio increased from 0.5 to 3 the weight percentage of ethyl acetate production of distillate increased clearly due to high conversion rates of hac to etoh. on the other hand, figure (10) shows that the ambylite 400 catalyst gives the highest conversion rates of hac than other two types of catalysts for all reflux ratios studied. this is due to the high surface area of ambylite 400 catalyst 34.8 m 2 that is available for chemical reaction than that of 26.2 and 21.5 m 2 for zerolit 225 and zerolit 226 respectively. khalid a. sukkar al-khwarizmi engineering journal, vol. 4, no. 2, pp 1-9 (2008) 7 fig. 10. effect of reflux ratio on % conversion of hac to etoh. conclusions combining catalytic reaction and separation in the same reactor can improve the conversion and selectivity for much equilibrium limited reactions reduce capital cost and also enhance catalyst lifetime. in semi-batch operation mode, results pointed out that, the column-b(packed) shows higher conversion rates than that of column-a (fractionation). this is attributed to the high surface area available for liquid vapour contact in packed type column, which leads to increase in the rates of mass transfer. on the other hand, ambylite 400 catalyst shows higher activity for esterification reaction than other two types (zerolit 225 and zerolit 226). esterification process is regarded one of highly exothermic reactions, therefore, the temperature distribution along column axial for all three types of catalysts is essentially the same due to steady state operation in continuous operation mode. on the other hand, the effect of reflux ratio on temperature distribution is clearly noted, that as the reflux ratio increases the temperature distribution along the column is reduced for all types of catalysts. the experimental results point out that, as a reflux ratio increases the conversion rates of acetic acid increases. this is due to high mass transfer rates between vapour and liquid. therefore, increasing reflux rates enhances separation and recycles unreacted reactants to the reaction zone and, thereby, increases conversion. nomenclature column-a a fractionation type reactive distillation column with rods trays. column-b packed reactive distillation column. conv.% percentage conversion dp particle diameter of the catalyst [mm] etac ethyl acetate etoh ethyl alcohol (ethanol) hac acetic acid h2o water r reflux ratio rd reactive distillation acknowledgment the authors gratefully acknowledge the financial support provided for this work by ministry of higher education and scientific research/ scientists and creators dept.-baghdadiraq. references [1] kloker, m., keing, e. y., gorak, a., markusse, a. p., kwant, g. and moritz, p., “investigation of different column configurations for the ethyl acetate synthesis via reactive distillation”, chemical engineering and processing, 43, 791-801 (2004). [2] saha, b., chopade, s. p. and mahajani, s. m., “recovery of dilute acetic acid through esterification in a reactive distillation column”, catalysis today, 60, 147-157 (2000). [3] xu, z. p. and chuang, k. t., “kinetics of acetic acid esterification over ion exchange catalysts”, the canadian journal of chemical engineering, 74, 493-500 (1996). [4] aiouache, f. and goto, s., “reactive distillation-pervaporation hybrid column for tert-amyl alcohol etherification with ethanol”, chemical engineering science, 58, 2465 2477 (2003). [5] bianchi, c. l., ragaini, v., pirola, c. and carvoli, g., “a new method to clean industrial water from acetic acid via esterification”, applied catalysis b: environmental, 40, 93-99 (2003). [6] tang, y. t., huang, h.p., and chien, i. l., "design of a complete ethyl acetate reactive distillation system", j. chem. eng. japan, 36, 1352-1363 (2003). [7] tang, y. t., huang, h.p., and chien, i. l., "plant-wide control of a complete ethyl acetate reactive distillation process", j. khalid a. sukkar al-khwarizmi engineering journal, vol. 4, no. 2, pp 1-9 (2008) 8 chem. eng. japan, 38, no.2, 130-146 (2005). [8] chang, y. a., and seider, j. d., “simulation of continuous reactive distillation by a homotopy-continuation method,” chem. eng. sci., 12, 1243-1255, (1988). [9] bock, h., jimoh, m. and wozny, g., “analysis of reactive distillation using the esterification of acetic acid as an example,” chem. eng. technol., 20, 182-191, (1997). [10] gangadwala j., mankar, s., mahajani, s., kienle, a. and stein, e., “esterification of acetic acid with butanol in the presence of ion-exchange resins as catalysts”, ind. eng. chem. res., 42, 2146-2155 (2003). [11] gangadwala, j., kienle, a., stein, e. and mahajani, s., “production of butyl acetate by catalytic distillation: process design studies”, industrial and engineering chemistry research, 43, 136-143 (2004). [12] teo, h. t. r. and saha, b., “heterogeneously catalysed esterification of acetic acid with iso-amyl alcohol: kinetic studies”, journal of catalysis, 228, 174-182 (2004). khalid a. sukkar al-khwarizmi engineering journal, vol. 4, no. 2, pp 1-9 (2008) 9 دراســــة سهوكيــــة واوتقال انكتهة وانحرارة في أعمذة انتقطـــير رات انمفاعـــم جمال ماوع عهي. د, خانذ عجمي سكر.د*, ماجذ سهيم رضاعه. د ويران ماووئيم , زيذون محسه شكور.د انؼـشاق– بـغــذاد / انضايؼــت انخكُٕنٕصٛـت / لغـــى انُٓذعـت انكٛـًٛأٚــت* انخالصة reactive distillation باعخخذاو حمُٛت انًفاػم رٔ انخمطٛش ethyl acetate حى دساعت ػًهٛت ححضٛش خالث االرٛم فٙ ْزا انبحذ حٛذ حى اعخخذاو رالرت إَٔاع يـٍ انؼـٕايم انًغاػذة . باعخخذاو االٚزإَل ٔحايط أنخهٛك كًٕاد أٔنٛت نهخفاػم ٔاعخخذاو انؼٕايم انًغاػذة انصهبت cation exchanging resinsْٙ ٙٔانخ : zerolit 225, zerolit 226 , and ambylite 400 . ٍٛخالل انبحذ حى بُاء يُظٕيخٍٛ سٚادٚخ بأسحفاػاث rectifying, reactive and stripping sectionكم يُظٕيت حخكٌٕ يٍ رالد يُاطك ْٙ . بأبؼاد يٕحذة إلصشاء انخضاسب فٙ حصًًٛٓا كَٕٓا ححخٕ٘ ػهٗ صٕاَٙ َٕع (-column-a)اػخًذث انًُظٕيت األٔنٗ . عى لطش نهؼًٕد2,5عى ػهٗ انخٕانٙ ٔ (60+25+20) (trays (fractionation , أيا انًُظٕيت انزاَٛت (column-b-) ٕفصًًج ػهٗ أَٓا ػًٕد حمطٛش يحش((packed distillation column . يهى5 يهى ٔلطش خاسصٙ 4يهى ٔلطش داخهٙ 10ححخٕ٘ ػهٗ حشٕاث صصاصٛت اعطٕاَٛت انشكم بطٕل ٔانًُظ semi-batchانًُظ األٔل ْٕ ػًم َصف انٕصــــبت: أصشٚج انخضاسب باعخخذاو ًَطٍٛ يٍ انخشغٛم ػهٗ أعاط يشٔس انًٕاد األٔنٛت حٛذ اعخخذو انًُظ األٔل نغشض حمٛٛى كفاءة انؼٕايم انًغاػذة انًغخخذيت ٔححهٛم ٔحمٛٛى أداء . continuousانزاَٙ ْٕ األعهٕب انًغخًش حٛذ أظٓشث انُخائش أٌ انًُظٕيت انزاَٛت . األحٙ اعخخذيٍ فٙ انبحذ(fractionation and packed column) انخصًًٍٛٛ نهًُظٕيخٍٛ column-bٗأػطج يؼذالث كفاءة ٔححٕل ػانٛت َحٕ انُٕاحش انًشغٕب بٓا أكزش يٍ انًُظٕيت األٔن column-a. ْٔزا فٙ حمٛمت األيش ٚؼٕد ٔانز٘ ٚؤد٘ , إنٗ انًغاحت انغطحٛت انؼانٛت نهحشٕاث ٔانخٙ حٕفش يغاحت حاليظ صٛذة بٍٛ انبخاس انصاػذ ٔانغائم انز٘ ُٚضل يٍ أػهٗ انبشس أػطٗ فؼانٛت أػهٗ فٙ حفاػم ambylite 400يٍ َاحٛت أخشٖ أظٓشث انُخائش أٌ انؼايم انًغاػذ َٕع . بطبٛؼت إنٗ صٚادة يؼذالث اَخمال انكخهت . االعخشة يٍ انُٕػٍٛ اٜخشٍٚ حٛذ حؼذ حفاػالث االعخشة يٍ . فمظ ٔباألعهٕب انخشغٛهٙ انًغخًش-column-b يٍ َاحٛت أخشٖ حى اػخًاد انؼًم باعخخذاو انًُظٕيت ٔنٓزا يخابؼت حٕصٚغ دسصاث انحشاسة ػهٗ طـــٕل انبشس ٔنألَٕاع انزالرت يٍ انؼٕايم انًغاػذة أظٓشث انُخائش باٌ , انخفاػالث انباػزت نهحشاسة ٔيٍ خالل . ْٔزا ٚؼضٖ إنٗ حانت االعخمشاس انخشغٛهٙ فٙ أعهٕب انخشغٛم انًغخًش, انخٕصٚغ انحشاس٘ حمشٚباً يخغأ٘ نضًٛغ انؼٕايم انًغاػذة أظٓشث انُخائش اَّ كهًا صادث يؼذالث انشاصغ كهًا اَخفضج , ػهٗ حٕصٚغ دسصاث انحشاسة فٙ انبشسreflux ratioدساعت حأرٛش َغبت انشاصغ . يؼذالث حٕصٚغ انحشاسة داخم انبشس ٔنضًٛغ األَٕاع يٍ انؼٕايم انًغاػذة حٛذ ًٚكٍ حفغٛش يزم ْزِ انضٚادة ػهٗ , أشاسث انُخائش انؼًهٛت إنٗ ال اَّ بضٚادة لٛى انشاصغ فاٌ يؼذالث ححٕل حًط أنخهٛك عٕف حضداد . أعاط انخحغٍ انحاصم بًؼذالث اَخمال انكخهت بٍٛ انبخاس انصاػذ ٔانغائم انُاصل فٙ بشس انخمطٛش رٔ انًفاػم adsorption of cd (ii) and pb (ii) icons al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 5, no. 4 , pp 13-17 (2009) adsorption of cd(ii) and pb(ii) ions from aqueous solution by activated carbon hayder mohammed abdul-hameed department of environmental engineering/ college of engineering/ university of baghdad (received 30 december 2007; accepted 9 november 2009) abstract heavy metal consider as major environmental pollutants. many of industrial wastewater effluents contain a wide range of these heavy metals. the adsorption of cd2+ and pb2+ metal ions from aqueous solution by activated carbon was studied. the results showed that maximum adsorption capacity occurred at 486.9×10-3 mg/kg for pb2+ ion and 548.8×10-3 mg/kg for cd2+ ion. the adsorption in a mixture of the metal ions had a balancing effect on the adsorption capacity of the activated carbon. the adsorption capacity of each metal ion was affected by the presence of other metal ions rather than its presence individually. the study showed the presence of other heavy metals attribute to the reduction in the activated carbon capacity, and the adsorption process was found to obeys the freundlich isotherm for both ions. keywords: adsorption, heavy metal ions, aqueous solution, activated carbon 1. introduction a great interest in the research for the removal of heavy metals from industrial effluents had concentrated on using materials such as activated carbon, that is easy handle, economical and durable materials. adsorption process considered as technique for the removing of heavy-metal from industrial, mineral and petroleum industry, (volesky and holan, 1995). this process is mainly less cost and can be executed on site, hence, reducing the hazards of transport the toxic materials to the de-pollution sites. the adsorption process is a good alternative for the recovery of metals contained in other media (gavrilescu, 2004). the use of carbon for its adsorption qualities was known since 1530 b.c. when charcoal was utilized in the purification of medicines, and, in the field of water treatment, both ancient egyptians and eighteenth century sailors utilized charcoal lined vessels to provide a clean drinking water. the use of activated carbon filters were introduced in the 1930's for the ultra pure of water in the food industry. industry has also taken advantages of the unique ability to adsorb a variety of organic and non-organic compounds by utilizing the activated carbon in industrial wastewater treatment (benjamin, 1999). the freundlich equation has been widely used for many years. this equation which originally proposed as an empirical equation is used to describe the data for the heterogeneity in the adsorbent surfaces, in which the energy term (b) in the langmuir equation varies as a function of surface coverage (qe), that due to variations in the heat of adsorption (weber and walter, 1979). freundlich studied the adsorption phenomenon and showed that adsorption from solution could be expressed empirically by: n/1 ee ckq  … (1) when, (k and n) are constants, and n > 1 (lucas and cocero, 2000). as freundlich equation is an empirical equation then it is useful as a means for data description. data are usually fitted to the logarithmic equations as follows: ee clog n 1 klogqlog  … (2) hayder m. abdul-hameed al-khwarizmi engineering journal, vol. 5, no. 4, pp 13-17 (2009) 14 this equation gives a straight line with a slope of (1/n) and an intercept equal to the value (log k), for c = 1. the intercept is roughly indicated of adsorption capacity. freundlich equation generally agrees quite well for the experimental data of a wide range of concentration (robert and craft, 2000). zenedy and murphy (2007) found that the equilibrium data for adsorption of mercury onto activated carbon were correlated well with langmuir and freundlich equations. prasert and parasaut (2006) found that the activated carbon can be examined for removal of copper and lead from aqeous solution and the freundlich isotherm models well fitted the data. badmus and anyate (2007) showed that the adsorption isotherm of lead onto activated carbon seemed generally to approach freundlich models. diarati and taliki (2003) showed that the freundlich isotherm fits well the data of adsorption ff cadmium by powdered activated carbon at 30oc. qader and akhtars (2005) found that the adsorption kinetic study of lead and cadmium individually, the resulted data fits well freundlich isotherm. the mechanism of adsorption may be particle diffusion controlled (ligwa and addiat, 2003) or a film diffusion controlled depends on many parameters that will dominate which mechanism of the above of favourable depends on the slowest step of the adsorption process that will consider the rate step. here the result of the amount adsorbed against time for a mixture of the metal ions. since adsorption is a particle diffusion controlled ((ligwa and addiat, 2005) and this could be effected by the following processes: (i) diffusion of the solute from the solution to the film surrounding the particle; (ii) diffusion from the film to the particle surface (external diffusion); (iii) diffusion from the surface to the surface to the internal sites (surface diffusion or pore diffusion), and (iv) uptake which can involve several mechanisms: physicochemical sorption, ion exchange, precipitation or complexation (digiano, 1996). the first process is bulk diffusion, the second is the external mass transfer resistance and the third is intraparticle mass transfer resistance. when the adsorption is particle diffusion controlled, it means that intraparticle mass transfer resistance is rate limiting. therefore, in the presence of a mixture of the metal ions, the metal ions (i.e. compete) for the adsorption sites on the adsorbent. this competition affects the diffusion properties of the metal ions, hence decreases the adsorption capacity of the metal ions. thus, the metal ion that successfully reaches the adsorption site faster depends on the above factors and also on the ionic radii of the metal ions. competition among the metal ions for adsorption sites deviously affected the adsorption capacity (ligwa and addiat, 2003). it seems that surface attachment might also be taking place on the functional groups on the surface of the adsorbent. more of what happens is volumetric filling of the micro-pores found in the adsorbents. since adsorption takes place in these micro-pores (motoyuki, 1990), these results decreases in the amount of metal adsorbed with time, by inspection of the plots, the application of the lagergen equation (equation 3) shows a zero order reaction. this is true since amount adsorbed remain fairly constant with increased time. the lagergen equation is given by: log (qe-q) = log qe – kad t/2.303. … (3) where q is amount adsorbed (mg/g) at time t, qe is amount adsorbed (mg/g) at equilibrium time and kad is the rate constant of adsorption (min-1) (ligwa and addiat, 2003). 2. scope of study in this work activated carbon used as adsorbent for the removal of cd(ii) and pb(ii) ions and the mechanism of sorption were investigated respectively. the effect of having two metal ions in the wastewater had been studied. since the pollution of the environment with heavy metals is important and as result of many human industrial, agricultural and petroleum activities, it means that these effluents would carry heavy metal ions in solution. 3. materials and method all materials used are from the iraqi market, a solution of cd(no3)2.2h2o and pb(no3)2.4h2o were prepared with initial concentration of 1000 mg/l by the dissolving 2.75 gm of pb(no3)2.4h2o in 2.5 l of distilled water and 1.82 gm of cd(no3)2.2h2o in 2.2 l distilled water. the average particle size used is 400  m, hayder m. abdul-hameed al-khwarizmi engineering journal, vol. 5, no. 4, pp 13-17 (2009) 15 the process of screening was held in the petroleum research and development center lab / ministry of oil using screen shaker of type (baus). 20 ml of each of two metal ions were mixed and put in a conical flask containing 0.5 g of activated carbon. the flask was uniformly agitated at a temperature of 25oc and optimum ph of 7 using a rotary shaker. figure (1.a) shows the agitation process using rotary shaker at constant agitation speed. fig.1.a. agitation process for different flasks the experimental set-up was repeated for time intervals of 20, 30, 40, 50, and 60 min after the end of every (10min) a sample was taken from the flask and the concentration of (pb, cd) in the filtrate water was measured using atomic absorption device in the baghdad environmental directory / ministry of environment. figure (1.b) shows the samples after treatment with activated carbon. fig.1.b. the samples after treatment with activated carbon 4. results and discussion the amount of the adsorbate adsorbed at different time interval for both cd, pb ions were measured and table (1) indicates the values of these amounts. table 1, amount of adsorbate adsorbed by activated carbon time (min) amount cd adsorbed (mg/kg)×10 3 amount pb adsorbed (mg/kg)×10 3 10 548.80 486.90 20 515.20 477.11 30 547.31 473.20 40 542.01 471.75 50 530.57 475.54 60 545.71 436.71 figure (2) show the amount of metal adsorbed against time for activated carbon, 1000 mg/l initial metal ions concentration and 400  m average particle size. fig.2. amount adsorbed (mg/kg) verse time (min) for cd(ii), pb(ii) ions on activated carbon of 400μm average particle size at 1000 mg/l initial mixed metal ion concentration from figure (2), its clear that the adsorption was unsteady for pb(ii) but varied a little for cd(ii) on activated carbon. the adsorption will expected to become less varied in the curve behaviour as preceding the time interval. by applying (equation 1) the equilibrium concentration for each ions ce at different qe values were calculated and tabulated in table (2). by applying the linearized form of freundlich isotherm model, equation (2) to the data in tables (1) and (2) and plotting the equation, a straight line will be resulted according to the model isotherm as in figure (3) which refers to a good hayder m. abdul-hameed al-khwarizmi engineering journal, vol. 5, no. 4, pp 13-17 (2009) 16 fitting of the data with freundlich isotherm for both cd and pb. table 2, equilibrium concentration ce (mg/l) for cd and pb cd pb 862.60 878.20 871.20 880.70 863.17 881.70 864.49 882.06 866.07 881.11 863.57 890.89 fig.3. the linearized form of the equilibrium concentration for both cd and pb 5. conclusion the amount of cd(ii), pb(ii) metal ions in aqueous solutions adsorbed did not increase as time increased as expected. rather, the amount adsorbed remained fairly constant with time during the competitive sorption. this was attributed to the fact that all the metal ions, will have to be struggling for the same number of adsorption sites at the same time. therefore, this study significantly reveals that the presence of other heavy metals and chemicals are influential factors and should be design parameters in the treatment and management of heavy metal pollutants using activated carbon. furthermore, the fluctuation in the amount of cd adsorbed with respect to time rather than pb may attribute to the high affinity of the pb rather than cd for adsorption onto activated carbon due to the variation in the electro-charges properties of both ions. as pb is more attracted (attached) than cd on the vacant sites of the activated carbon due to is less positively than cd. both cd and pb obeys well freundlich isotherm. 6. references [1] badmus i. m., anyate, k. p., "removal technique of pb from wastewater", (2007), who publications. [2] benjamin j., "adsorption of chromium from electroplating industry", (1999), sci. journal: 1031-1034. [3] diarati i. m., taliki h. m, "reduction of cd ion concentration from electroplating effluent by activated carbon", (2003), iranian journal sci. vol.3. [4] digiano j. b., "mechanism of mass transport in porous media", (1996), chem. j., vol. 8, p:320-331. [5] gavrilescu m., "removal of heavy metals from the environment by sorption", (2004), engineering in life sci. 4(3): 219-202. [6] ligwa j. c., addiat a. a., "bio-remediation of co(ii), fe(ii) ions from wastewater using modified and unmodified maize", (2005), sorption kinetic and inter-particulate diffusivity, j. biotech. [7] ligwa j. c., addiat a. a., "maize and husk as adsorbent for removal of cd, pb and zn from wastewater", (2003), the physical sci 2:210-215. [8] lucas, a. c., cocero, r. r., "bio-sorption of heavy metals using natural materials", (2000), aggri. sci journal, p:1010-1014. [9] motoyuki, s., "adsorption engineering", (1990), elesevier sci. puplishers, pp:5-61. [10] prasert m. n., parasaut j. e., "kinetic study for adsorption of cu, hg from sodium hydroxide factory", (2006), environmental journal, vol.11, p:301-308. [11] qader m. a., akhtars k. n., "kinetic analysis for pb, cd adsorption", (2005), indian journal of environmental, vol. 9, p:951-453. [12] robert b. m., craft j. z., "modeling of surface phenomena processes", turkish journal of chemistry, vol. 7, (2000), p:215221. [13] volesky b., holan z., "bio-sorption of heavy metal biotechnical prog", (1995), 11:235-250. [14] weber j. c., watter h. c., "adsorption isotherms model", (1974), chemical, j. p.: 211-214. 2.88 2.90 2.92 2.94 2.96 2.60 2.70 2.80 2.90 3.00 cd pb l o g q e log ce 2.88 2.90 2.92 2.94 2.96 2.60 2.70 2.80 2.90 3.00 cd pb 17-13، صفحة 4 ، العذد 5 مجلة الخىارزمي الهىذسية المجلذ حيذر محمذ عبذ الحميذ (200 9) 17 دراسة عملية االمتساز أليىوي الكادميىم والرصاص مه محلىل مائي باستخذام الكاربىن المىشط حيذر محمذ عبذ الحميذ جبيعت بغذاد/ كهٍت انهُذست/ قسى هُذست انبٍئت الخالصة . حعخبر انًعبدٌ انثقٍهت يٍ اهى انًهىثبث انبٍئٍت وهُبنك انعذٌذ يٍ انصُبعبث انخً ححخىي يٍبههب انصُبعٍت عهى طٍف واسع ويخخهف يٍ انًعبدٌ انثقٍهت ٌهذف انبحث انى دراست عًهٍت االيخساز نكم يٍ اٌىٌ انكبديٍىو وانرصبص ضًٍ يحهىل يبئً ببسخخذاو انكبربىٌ انًُشظ وقذ وجذ اٌ اعهى قًٍت ناليخساز واٌ سعت االيخساز نالٌىٍٍَ بصىرة يُفردة حقم عُذ . الٌىٌ انكبديٍىو (كغى/يهغى3-10×548.8)الٌىٌ انرصبص و (كغى/يهغى3-10×486.9)بهغج يقبرَخهب يع سعت االيخساز عُذ حىاجذ االٌىٍٍَ يع بعضهًب انبعض ضًٍ انًحهىل انًبئً واٌ حىاجذ االٌىٍٍَ يع بعضهًب انبعض ضًٍ انًحهىل انًبئً ٌؤدي انى انًىازَت فً انخأثٍر نكم يٍ االٌىٍٍَ عهى سعت االيخساز يًب حؤدي انى حقهٍم يٍ سعت االيخساز ، واٌ عًهٍت االيخساز نكال االٌىٍٍَ ٌخضعبٌ نًىدٌم . فرٌُذنخش انرٌبضً ناليخساز (microsoft word \343\321\346\307\344 \346 \314\343\307\3414550) al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 15, no. 3, september, (2019) p.p. 4550 effect of shot peening on fatigue properties for corroded and uncorroded (ck35) steel marwan n. arbilei* jamal mohammed hamed** *,** department of biomedical engineering/ university of technology/ baghdad/ iraq *email: engmna@gmail.com **email: jamal_hamed2001@yahoo.com (received 13 november 2018; accepted 27 march 2019) https://doi.org/10.22153/kej.2019.03.002 abstract the traction property is one of the important mechanical properties, especially the rotary parts which are subjected to constant and variable loads there are many methods used to improve this property, and the shoot peening by metal balls is considered the most critical one. the study focuses on this characteristic of steel ck35 used in many engineering applications as the rotating shafts and railway this study shows that the fatigue strength is improved by14% after shoot peening with metal balls. the study includs the rehabilitation of damaged samples as a result of fatigue corrosion. the standard solution adopted was 36% mgcl2 with a 30 days immersion period. these samples has been improved by 6% after it decreased by18% due to immersion in the alkaline solution. keywords: crevice corrosion, ck 35, fatigue strength, shot pining. 1. introduction there are many methods for surface hardening; the-chemical methods, such as carburizing and nitriding. physical methods showed a better interest with changing the chemical composition of treated alloys. one of these methods is shot peening with metal balls. the theory depends on the resist of nucleation and growth of cracks. cracks and growth are with time working. this is required by many alloys subjected to continuous vibration and forces especially those used in bone fixation [1]. all the above listed methods increase surface hardness by producing compressive residual stresses. the surface plays a key role in the life of the metal parts, especially the fatigue age which is related to the formation and growth of cracks on the surface [2]. the shoot peening process depends on many variables, such as the speed of balls, the time spent on the process of solidification, and the dimensions of the balls used in the process of molding and shape [3]. in this study, used alloy steel (ck35) is used which resist vibration the presence of an auxiliary medium on corrosion leading to the acceleration of the process of the emergence of the crack and progress., the resistance of metal to the fatigue in the corrosion medium is less than in the nonhelping to corrosion [4] in that the number of cycles necessary to break the corrosive medium which is less than the number of cycles required to obtain the fracture in the other medium when the same voltage value is applied to the alloy. [5,6]. the selection of shoot metal balls is as a method of surface hardening to obtain better properties of metal is to satisfy their requirements and efficiency. the shoot method of balls is applied to treat the damage caused by corrosion when the metal is exposed to hard corrosive media. the shoot of the balls leads to the closure of the pressure and some short cracks and impedes its progress, which improves the surface properties of the metal especially fatigue resistance. the marwan n. arbilei al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 4550 (2019) 46 objective of this research is to raise the efficiency of the metal chosen for studying as a common metal used in the engineering parts and improve its properties by increasing the hardness of the surface and to maintain a strong heart to withstand shocks 2. experimental work 2.1 material the alloy was in the form of rods with various lengths and diameters, which were machined by cnc to obtain accurate dimensions. then, the samples surfaces were grinding and polished to avoid stress concentration areas. fig 1 has showed the standard dimensions of the sample supplied with testing device used in rotational bending tests. the chemical composition and mechanical properties of ck35 illustrated in tables 1 and 2, according to aisi1035. fig. 1. standard fatigue sample (iso 1143:2010 en) table 1, chemical composition fe other mn si c element rem <1% ≤0.65 ≤0.40 0.35 standard rem 0.7% 0.6 0.33 0.34 investigated table 2, mechanical properties according to aisi 1035 2.2 machines and instruments 2.2.1 testing machine the hi-tech rotating bending fatigue testing machine tester is used. the rotating speed of 5600 rpm where 1/3 million stress reversals occur per hour. fig. 2. testing machine. 2.2.2 shoot peening device the shooting is performed using a shoot device where a ball bearing cast steel balls and the parameters as illustrated in table 3. fig. 3. shoot device. hardness(hb) є% σult. (mpa) σ yield (mpa) 190 21 480-670 300 sample switch motor control system balls marwan n. arbilei al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 4550 (2019) 47 table 3, parameters of shot peening 2.2.3 optical microscope optical microscopic imaging has been used to investigate the fracture section surface fir both types of samples (shoot peening and corrosion). the magnification for all samples was 500x) 2.2.4 high precision electronic balance accuracy (10-5 gm) 2.3 corrosion test medium a standard corrosion test was selected to test for the resistance of fatigue, magnesium chloride at a concentration of 36% mgcl2 (astm g36). this test solution was prepared by dissolving 360 g of high purity magnesium chloride per liter of distilled water. the ph of the solution daily was measured to keep the solution stable during testing time by adding more salt and water to corrosion cell. 2.4 test groups test groups were classified into four groups according to the type of mechanical and chemical treatment. where 24 samples for each group have been machines by using indexed turning machine. according to the standard specimen shown in fig. 1. table 4, group of samples coding type of test group as received as after shot peening sp after corrosion cr after corrosion and shot peening crsp 3. results and discussion to draw the s – n curve which is illustrated in fig (4), the titration test is performed on eight groups of samples. each group consisted of three samples by casting a constant value of stress for each group and calculating the value of the number of cycles failures for each sample to give more accuracy to the obtained results and to eliminate the random behavior of the samples. the same tests are repeated for the same number of samples with metal balls. the same tests is performed after the samples are immersed in salt solution. then, the samples is cast with metal balls and the tests is carried out as shown in fig (4) age-adjusted equations for the results is obtained in fig (4) using a best curve fitting method and are as in table (5) table 5, equation and fatigue limit enhance ment % fatigue limit fatigue equation samples group 14% 320 σf = 1184nf -0.093 sp 280 σf = 1216nf -0.102 as 6% 265 σf = 1259nf -0.112 crsp 250 σf = 11446nf -0.11 cr the fig (4) and table (5) show the increased fatigue limit and fatigue resistance of the alloy with the shooting of the metal balls compared with the test performed without shooting. this increase value is due to the exposure of the sample to a surface hardening process. the hardening of the surface leads to obstruction and even in the case the emergence of such cracks. the increase with shooting is about 14%. when test in solution (36% mgcl2) according to astm g36, the sample – typically u-bend – is immersed in a boiling mgcl2-solution. the time to cracking is an indication of the resistance to stress corrosion cracking. this test causes a decrease in the weight of the alloy comparing to the test conducted under dry conditions. this decrease is due to the immersion of these samples in the salt solution which influenced efficiency on the samples. clicking on the surface and thus cracks develop faster because of the combined effect of stress and corrosion. the continued effect of this medium causes more pits and the formation of many cracks and makes these cracks faster [8]. the decrease in the value of the threshold was about 18%. the shooting of the specimens led to the termination and closure of the pits caused by the salt solution and the creation of compressive stresses on the surface hardening the progress of the crevices. the increase in properties unreturned samples to their original state due to the corrosive parameter value diameter ball 0.6 mm hardness(hrc) 50 pressure 12 bars speed 40 m/s distance between ball and machine 10 mm speed of lathe machine 20 rpm marwan n. arbilei al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 4550 (2019) 48 effect of the salt solution, the value of the increase was 6%. the corrosion rates of the tested samples are presented in table (6). fig. 4. (s – n) curve for test specimens. table 6, corrosion rates of samples type of test as sp cr crsp weight loss (g) 0.0530 0.0355 0.0815 0.0670 it is noted that the weight loss due to corrosion decreased with shoot metal balls while this rate increased when immersed in salt solution and decreased again when the cast of metal balls has been shoot. this is in line with the results of the tests presented previously. the fracture sections as shown in fig 5 has reveled a finer cracking in the shot samples, in addition to stress cracking has been avoided in the shot samples after corrosion. 4. conclusions shot peening increases the fatigue resistance for the un corroded samples with 6% meanwhile the fatigue resistance has a better enhancement with the uncorroded samples with 14%. the weight loss due to corrosion of shot samples overcomes the cervices corrosion. the fatigue resistance can be enhanced and maintained perfectly even after corrosion. acknowledgment special thanks are forwarded to the department of biomedical engineering university of technology baghdad-iraq a: without shoot (200x) b: with shoot (200x) hard cracking fine cracking marwan n. arbilei al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 4550 (2019) 49 c: corrosion (200x) d: corrosion + shoot (200x) fig. 5. fracture surface of four cases. 5. references [1] a. stoic, j. kopac, “turning condition of ck35 steel with alternate hardness zones” journal of achievements in materials and manufacturing engineering, vol 34, issue 1 ,2009. [2] f. abadie, l. barrlier, “ceramic shot enhancement of high strength steel endurance application to springs and gears”, icspa shot peening, 2015. [3] t. saeid, s. yazdani, “shot peening as an alternative to fatigue life improvement of ck35 steel coated with an electroless ni-cu-p”, international journal of issi, vol2, 2015. [4] aleksander, grzegorz, waraw, “effect of shot peening on the fatigue strength of spring steel after exposure to corrosion”, poland, 2005. [5] yoshiki, james, “effect of shot peening on fatigue damaged high strength aluminum alloy applicability of rejuvenation on fatigue damaged compopents” university, syracuse, new york, 2012 [6] hill.s, gregson and hara, “effect of shot peening on fatigue performance of advanced aluminum alloys and aluminum based metal matrix composites” engineering materials, university of southampton, uk. 2010 [7] alkawi. h. j, awsi. m. q, “influence of shot peening on 70/30 brass residual stresses using plasticity theory” engineering and technology , issn: 16816900 24120758 year: 2009 volume: 27 issue: 16 pages: 3064-3075 iraq , 2009. [8] w. 6th street mishawaka, “shot peening overview” j. champaigne, electronics inc 1428, in 46544, usa 2000. [9] s. romero, e. rios, “optimization of the shot peening process in terms of fatigue resistance” presented at seventh international conference on shot peening, icsp-7 warsaw, poland, 1999. [10] zuhal abd alzahra, "shot peening time effect on corrosion behaviors of al alloy 2024-t3" khwarzmi engineering journal, v12,no1,page 110-116, 2016 [11] zainab azeez betti, amer hameed maajeed, alalkawi h.j.m." interaction of corrosioncumulative fatigue and shot peening of 1100-h12 aluminum alloy" al-khwarzmi engineering journal, v11,no1,page 65-72, 2005. less stress corrosion cracks stress corrosion cracks )2019( 4550، صفحة 3، العدد15دجلة الخوارزمي الهندسية المجلم مروان نافع علي 50 ck35تأثير القذف بالكرات على خواص الكالل لعينات متآكلة وغير متآكلة للفوالذ **جمال محمد حمد *مروان نافع علي العراق/ بغداد /قسم هندسة الطب الحياتي/ الجامعة التكنولوجية*،** engmna@gmail.com :البريد االلكتروني* jamal_hamed2001@yahoo.com :البريد االلكتروني ** الخالصة ). حيث تضمن البحث دراسة اربع حاالت من خالل اختبار الكالل. الحالة االولى للعينات ck35تم في هذا البحث دراسة تحسين خواص الكالل للفوالذ ( ينات مغمورة في محلو كما أستلمت. والحالة الثانية تم فبها اختبار الكالل بعد اجراء بسمرة بالقذف بكرات حديدية. والحالة الثالثة كانت بأختبار الكالل لع 2mgcl و الحالة الرابعة واالخيرة كانت باختبار العينات المغمورة بعد اجراء بسمرة القذف بكرات الحديد. حيث تحسنت مقاومة يوما. ٣٠لمدة %٣٦بتركيز . و بعد أجراء البسمرة بالقذف طرأ تحسن %١٨. بينما انخفضت خواص الكالل بالنسبة للعينات المغمورة بنسبة %١١الكالل للعينات بعد بسمرة القذف بنسبة . وعليه نجد ان القذف بالبسمرة من العوامل التي تعيد تأهيل العينات من ناحية مقاومة الكالل حتى بعد تعرضها %١٤الكالل لتلك العينات بنسبة على خواص للتآكل. al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 2538 (2014) an experimental study of the effect of vortex shedding on solar collector performance alaulddin abdulqader kadim department of engineering affair/ university of baghdad email:aldina81@yahoo.com (received 24 march 2014; accepted 13 july 2014) abstract in this work, the effect of vortex shedding on the solar collector performance of the parabolic trough solar collector (ptsc) was estimated experimentally. the effect of structure oscillations due to wind vortex shedding on solar collector performance degradation was estimated. the performance of ptsc is evaluated by using the useful heat gain and the thermal instantaneous efficiency. experimental work to simulate the vortex shedding excitation was done. the useful heat gain and the thermal efficiency of the parabolic trough collector were calculated from experimental measurements with and without vortex loading. the prototype of the collector was fabricated for this purpose. the effect of vortex shedding at different operation conditions was examined. the variation of angles of attack and wind velocity leads to different values of vortex loading coefficients and shedding frequencies. the relation between the dynamic characteristics and solar collector performance was evaluated. the finite element method was used to estimate the dynamic characteristic of the solar collector in addition to experimental work to evaluate the relation between the dynamic behavior of the collector and its performance. keywords: vortex shedding, solar collector efficiency, useful heat gain. 1. introduction in order to deliver high temperatures with good efficiency, a high performance solar collector is required. systems with light structures and low cost technology for process heat applications up to 400 ̊c could be obtained with parabolic through solar collectors (ptsc). ptsc can effectively produce heat at temperatures between 50 and 400 ̊c [1]. most of the solar power plants installed with parabolic collectors are on flat terrain and they may be subjected to some environmental problems. one of problems for large parabolic collector is their stability to track the sun with respect to time very accurately. any small off tracking as well as the collector structure stability will be affected by strong wind blowing for the regions where the wind velocity is high [2]. wind loading excites the structures to vibrate with specific deformation pattern called wind-induced vibration. this excitation induced due to many flow phenomenons such as vortex shedding, flutter, buffeting and fluidstructure interaction [3]. this flow phenomenon can affect the performance of solar collector significantly [4]. holmes et al. [5] studied flow pattern around a microwave dish. they studied wind drag forces on microwave dish antennas and their supporting lattice tower for different angles of attack. they found that, drag coefficient for an isolated dish is maximum with direction normal to the plane of the dish, but does not change in an angular window within 30˚ to the normal of the dish. raddu and axinte [6] studied the wind effect on solar flat-plate collectors. they found that when the wind direction is normal to the plate the drag coefficient is maximum. chevalien and norton [7] studied rows of solar panels on a model building in a wind tunnel and their sheltering effects. they founded that the number of rows and presence of alaulddin abdulqader al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 2538 (2014) 26 sheltering lead to significant decreasing in wind loading. kopp and surry [8] performed an experimental research on the total system torque measured at the main drive gear box used for panel’s solar tracking system. in this work, the effect of vortex shedding on collector performance was investigated experimentally. the experimental vortex shedding excitation was determined according to hybrid model and applied to the parabolic trough with specific magnitudes and frequencies. different values of vortex excitation magnitude and vortex excitation frequency are examined. then, the collection efficiency of parabolic trough solar collector was measured experimentally first without presence of vortex excitation and second with presence of vortex excitation. different angles of attack of wind and wind velocities are investigated. the tests were done by using special test rig fabricated for this purpose. the experimental tests have been carried out in baghdad (al-jaderiah) with climatic conditions (latitude of 33.3˚ n, longitude of 44.4˚ e and a standard time meridian of 45˚) during selected days of the months of august, september and october. 2. vortex shedding model for a bluff body in uniform cross flow, the wake behind the body is not regular but contains distinct vortices. the vortices are shed alternately from each side of the body in a regular manner and give rise to an alternating force on the body. experimental studies have shown that the frequency, in hertz, of the alternating lift force is expressed as [9]: fs = s u d ... (1) where s: the dimensionless number called the strouhal number, u: wind velocity (m/s) d: is the width of the object perpendicular to the flow (m) the strouhal number is determined only by experimental work. for solar collector, it depends on angle of attack of wind (θ). the angles of attack examined in current study are (30˚, 45˚, 60˚, 75˚, 90˚). these angles of attack are shown in figure (1). the values of strouhal versus these angles of attack are shown in table (1) [10]. the oscillating lift force imposed on a structure of length l and width d, in a uniform cross flow of velocity u, due to vortex shedding is given by [11]: f = 1 2 ρu2 cl dl sin 2πfst = fo sin (2πfst) … (2) where fo= 1 2 ρu2 cl dl t: time (s) the lift coefficient of solar collector is also depends on the angle of attack. the lift coefficient determined only by experimental work. the values of lift coefficient corresponding to the angles of attack are obtained by using boundary layer wind tunnel tests for the solar collector with specification shown in figure (2) [12]. these values are listed in table (2) [12]. the validity of boundary-layer wind tunnel testing for wind loads on structures is based on similarity arguments and on model-to-full-scale test comparison [12]. in current work, 1/4 modelto-fullscale was used and the specification of prototype shown in figure (2). fig. 1. the angles of attack. alaulddin abdulqader al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 2538 (2014) 27 fig. 2. specification of full scale solar collector and prototype used in current work. table 1, strouhal number versus the angle of attack [10]. θ 30˚ 45˚ 60˚ 75˚ 90˚ s 0.23 0.216 0.201 0.196 0.182 table 2, lift coefficient versus the angle of attack [12]. θ 30˚ 45˚ 60˚ 75˚ 90˚ cl 1.1 1.5 1.9 0.9 0.2 the oscillating lift force imposed on a parabolic trough can be computed for each angle of attack and wind velocity. 3. experimental representation of vortex shedding excitation the oscillating force due to vortex shedding can be simulated experimentally. the magnitude and frequency are calculated from equations 1 and 2. the experimental apparatus used to simulate the oscillating force is consist of: 1. function generator used supply wave signal with specific type, amplitude, and frequency 2. power amplifier used to amplify the signal which come from function generator. 3. electro-mechanical shaker used to supply excitation force to the structure. 4. nylon stinger connects the electro-mechanical shaker to the structure. alaulddin abdulqader al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 2538 (2014) 28 the apparatus can be used to supply oscillating force (harmonic or repeated) in specific magnitude and frequency. figure 3 shows the schematic diagram of the system of application of oscillating force. fig. 3. schematic diagram of oscillating force supply system. 4. solar collector setup the prototypes used in this study are fabricated by using special mold. a special composite material [polyester resin+ e-glass fiber] was applied to obtain the final product of parabolic trough solar collector. before applying the polyester and e-glass fiber layers, a layer of resin which called (gel coat) is applied. this layer will make the interior surface of trough very smooth. fine brushing was applied on the mixture of polyester resin and e-glass fiber (chopped fiber) to ensure isotropic properties for the material. then the interior surface coated by reflective material (mirror film) as shown in figure (4). fig. 4. the parabolic trough with reflective material and support frame. 5. solar radiation absorption and measuring system the first component of solar radiation absorption system is the reflective surface which was obtained by using reflective mirrors film as in figure (4) which has been introduced to concentrate solar technology as an alternative to mirrored glass reflectors. the second component is the copper pipe which is placed parallel to the rotation axis along the focal line. the wall thickness of the pipe is small (less than 0.5mm) to ensure quick transfer of energy from solar radiation to the working fluid which flow inside the pipe. black paint is used to cover the outside surface of the pipe to increase the absorbance of the incident solar irradiance and reduces the reflectance. the interior diameter of the pipe is (12 mm). pump of (0.1 kg/s) flow rate is used for circulating the water through a closed circuit consist of the absorbance pipe, flexible tube, connections and insulating storage tank. the water temperatures at inlet (ti) and outlet (to) of the absorber tube, water mean flow rate (mw), ambient temperature (tamb ) and solar radiation intensity (qs) are measured using two calibrated k-type thermocouples probes. the solar radiation intensity was measured by using a pyranometer. the schematic diagram of the experimental apparatus is shown in picture (5). the useful heat can be defined on the base of fluid difference temperature as [13] q = mw . cw . (𝑇𝑒 − 𝑇𝑖 ) … (3) and the solar collector efficiency is: ηc = mw .cw .(te−ti ) qs .a … (4) alaulddin abdulqader al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 2538 (2014) 29 fig. 5. the test rig. 6. natural frequencies and deflection measuring system natural frequencies was measured by using experimental modal analysis technique. the system of measuring included the excitation part and the response measuring part. the excitation part as previous included function generator, amplifier, electromechanical shaker, and nylon stinger. the response measuring system included piezoelectric accelerometer, charge amplifier and digital storage oscilloscope. the experimental results of natural frequencies are obtained by changing the excitation frequency and recording the behavior of the response of the structure to the changing of excitation frequency until the response of the structure reach to one of the peak values. the value of excitation frequency corresponding to one peak response equal to one value of natural frequencies. the response (deflection ) of structure to dynamic excitation are also measured and recorded by using piezoelectric accelerometer, charge amplifier, and digital storage oscilloscope. 7. numerical simulation the numerical simulation was used in current study to perform two types of analysis which are: 1modal analysis to estimate the natural frequencies for the structure. the estimation of natural frequencies was done to avoid applying excitation frequency close to any of these natural frequencies. applying excitation frequencies close to any natural frequency will lead to undesired response for the structure. 2harmonic analysis to estimate the response of the structure to harmonic excitation which will apply to structure to simulate the wind loading due to vortex shedding. the numerical simulation was done by using software package (ansys mechanical apdl). simulation parameters such as model geometry, boundary conditions, material properties, element type, and governing equation solution scheme are chosen carefully to give the optimum results of natural frequencies and the response to harmonic excitation. the numerical results of natural frequencies were verified with corresponding alaulddin abdulqader al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 2538 (2014) 30 experimental results. . the detailed information about simulation parameters and the figures of element type and meshing model are shown in appendix 1. 8. results and discussion first, the first five natural frequencies are estimated numerically and experimentally. table 3 lists the value of the first five natural frequencies. table 3, first five natural frequencies. natural frequency numerical(hz) experimental(hz) error percentage first 54 49 9.26 % second 63 61 3.17% third 78 71 8.97% fourth 94 88 6.383% fifth 112 103 8.03% the deformation of parabolic trough solar collector due to vortex shedding excitation will be introduced. the magnitude and frequency of vortex shedding excitation are computed and listed in table (4) for each angle of attack and wind velocity. the deflection of the parabolic trough is evaluated numerically and experimentally. figure (6 and 7) shows the deflection of the trough at each wind velocity and angle of attack. it is clear from these results that both angle of attack and wind velocity have an effect on deflection pattern of trough but the effect of velocity is larger than the effect of angle of attack. this estimation established because the difference in deflection pattern when the angle of attack is constant and wind velocity changed is larger than the difference in deflection when the velocity was constant and angle of attack changed. table 4, magnitude and frequency of wind excitation force. θ = 30˚ velocity (m/s) fs (hz) fo (n) 5 0.75 4.175 10 1.5 33.287 15 2.24 92.688 θ = 45˚ 5 0.7 5.314 10 1.4 42.4 15 2.1 142.366 θ = 60˚ 5 0.652 6 10 1.3 49.88 15 1.96 168.5 θ = 75˚ 5 0.636 2.897 10 1.272 23.12 15 1.9 77.4 θ = 90˚ 5 0.59 0.59 10 1.18 4.76 15 1.772 16 alaulddin abdulqader al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 2538 (2014) 31 figure (8) shows the maximum value of deflection of trough versus the angles of attack and wind velocity. it is observed that the deflection of trough has maximum value at angle of attack (θ = 60˚) and minimum value at angle of attack (θ = 90˚). this observation was recorded for all wind velocity. also, the value of deflection increases when wind velocity increases. this result is normal because the increasing of wind velocity will increase both excitation force magnitude and excitation frequency . fig. 6. deflection of collector surface at θ=30̊ and v=5m/s (dimension in mm). alaulddin abdulqader al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 2538 (2014) 32 fig.7. the deflection of trough at each wind velocity and angle of attack. alaulddin abdulqader al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 2538 (2014) 33 fig. 8. the maximum deflection of trough versus angle of attack and wind velocity. 9. solar collector performance parameters all parameters necessary for the calculation of collector performance are measured during different days of months august, september and october. these parameters are measured and collected first without vortex induced vibration and second with vortex induced vibration. then the performance of trough for specific angle of attack and amount of solar radiation with vortex induced vibration was compared with the performance of trough for the same angle of attack and amount of solar radiation without vortex induced vibration. table (5) lists the typical data necessary for performance analysis during the day from october month. then the thermal efficiency of trough are calculated for both cases and compared. figure (9) shows the thermal efficiency of solar collector for five angles of attack for period of time between 9:00 a.m. to 2:00 p.m. with and without vortex induced vibration. many observations can be drawn from this figure. the first observation is that the thermal efficiency of solar collector has different trend with angles of attack. for (θ =30˚ and 45˚), the thermal efficiency was noticed to be high during early hours of the day and then decreases around the mid noon and then increases after mid noon. this behavior of thermal efficiency is noticed for solar collector with and without applying vortex induced vibration. the reduction in thermal efficiency of solar collector around the mid noon can be attributed to the inertia of solar collector to transfer all solar energy to heat when the solar radiation reach to its maximum value at mid noon. the maximum value of thermal efficiency for both these angles of attack without vortex induced vibration is approximately (0.47) while the minimum value is (0.35) for (θ=30˚) and (0.33) for (θ=45˚). the applying of vortex induced vibration on solar collector leads to decreasing the value of thermal efficiency significantly. increasing of the wind velocity leads to more decreasing in the value of thermal efficiency. the larger decreasing in thermal efficiency occurs at wind velocity (15m/s). this reduction in thermal efficiency attributed to deviation of sun light because the changes in collector profile due to wind excitation. the amount of these changes in collector profile depends on the amount of external excitation and the vibrational characteristics of the structure. it is clear that the increasing of wind velocity leads to excite the structure to vibrate in high mode as shown in figure (6) because the increasing of wind velocity leads to increase the vortex shedding frequency. high mode of vibration means more concaves in collector surface and more deviations of sun light. it is clear from figure (6) that the increasing of wind velocity leads to increase the number of concaves on collector surface for all angles of attack. for (θ=60˚, 75˚ and 90˚) without vortex excitation, the thermal efficiency was noticed to exhibit little fluctuating around specific value along the test period. also, the thermal efficiency of solar collector with vortex excitation is noticed to be less than that without wind velocity and has fluctuated values around specific value except that for (θ=60˚) and vortex excitation 15m/s where large reduction in thermal efficiency is appear. this reduction increases as the local time increase until reach to maximum reduction at 12:00 o’clock. this reduction can be attributed to the effect of vortex excitation because that excitation was shown to be maximum at angle of attack (θ=60˚). diffusion alaulddin abdulqader al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 2538 (2014) 34 table 5, typical performance data of solar collector. time (hr) tamb (c˚) tin (c˚) tout (c˚) qs=id+ib w/m 2 id w/m 2 ib w/m 2 q (w) ηsys 9:00 33 43.1 44.3 462 77 385 504 0.425 9:30 34.3 45.2 46.5 515 80 435 546 0.407 10:00 35 48.7 50.1 571 81 490 588 0.390 10:30 35.5 54.3 55.8 629 84 545 630 0.375 11:00 36.1 60.5 62 678 85 593 630 0.345 11:30 36.7 64 65.6 728 88 640 672 0.340 12:00 37.3 68.4 70.1 775 91 684 714 0.338 12:30 37.5 72.4 73.7 701 86 615 546 0.288 1:00 37.9 77 78.3 688 85 603 546 0.294 1:30 38.5 80.2 81.6 672 82 590 588 0.323 2:00 38.9 84.3 85.7 660 79 581 588 0.328 also, the useful heat gain is computed for each angle of attack without vortex induced vibration and with vortex induced vibration. figure (10) shows the polynomial curveting of the results of useful heat gain without and with vortex induced vibration for two typical angles of attack (60˚ and 75˚). it is shown from this figure that the vortex induced vibration leads to remarkable decreasing in useful heat gain. this decreasing in useful heat gain increases with wind velocity at early time but become closely at after noon. also, the presence of vortex excitation does not change the trend of the gain where the maximum value of gain is recorded at about 12:00 o'clock when the vortex excitation is applied or not. alaulddin abdulqader al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 2538 (2014) 35 θ = 30˚ θ = 45˚ θ = 60˚ θ = 75˚ θ = 90˚ fig. 9. thermal efficiency of solar collector at each angle of attack with and without wind induced vibration. alaulddin abdulqader al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 2538 (2014) 36 fig. 10. useful heat gain for two angles of attack with and without wind induced vibration. 10. conclusions 1the presence of vortex induced vibration leads to decreasing both thermal efficiency and useful heat gain but does not change the trend of variation with local time. 2the increasing of wind velocity leads to more decreasing of thermal efficiency and useful heat gain. 3the maximum decreasing of thermal efficiency with vortex excitation is noticed at angle of attack (60˚ and 75˚). 4the excitation of the structure to vibrate at high modes of vibration will increase the degradation of the collector performance. notation a collector aperture area [m 2 ] cl lift coefficient cw water specific heat [kj/kg.k] d object diameter [m] f lift force [n] fs vortex shedding frequency [hz] mw water mass flow rate [kg/s] ptsc parabolic trough solar collector q heat gain [w] ib beam solar intensity [w/m 2 ] id diffusion solar intensity [w/m 2 ] qs total intensity of solar radiation [w/m 2 ] s strohal number ti inlet temperature [k] te outlet temperature [k] tamb ambient temperature [k] u wind velocity [m/s] greek letters θ angle of attack [degree] ρ fluid density [kg/m 3 ] ηc collector effeciency 11. references [1] eckhard, et. al, " eurotrough design issues and prototype testing at psa", proceedings of solar forum, washington, 2001. [2] yaghoubi m, sefidbakht s, kenary a. performance variation of 250kw solar thermal power plant for various locations in iran. in: proceedings of second international conference on energy research & development, state of kuwait, 2002. p. 765– 75. [3] paidoussis m.p., “fluid-structure interaction vol.2: slender structures and axial flow”, elsevier academic press, london, 2004. [4] mukund r. patel “wind and solar power systems: design, analysis, and operation”, taylor & francis, second edition, 2006. [5] holmes jd, banks rw, roberts g. drag and aerodynamic interference on microwave dish antennas and their supporting towers. j wind eng ind aerodyn 1993;50:263–9. [6] [6]raddu a, axinte e. wind forces on structures supporting solar collectors. j wind eng ind aerodyn 1989;32:93–100. [7] l. chevalien, j. norton, wind loads on solar collector panels and support structure, aerospace engineering department, texas a&m university (1979). alaulddin abdulqader al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 2538 (2014) 37 [8] g.a. kopp, d. surry, wind loads on solar array, wind and structures. 5, (2002) 393406. [9] alan g. davenport, milos novak, “vibration of structures induced by wind”, mcgraw-hill book company, inc., new york, 1966. [10] r. k. foran, “ vibration and flow field characteristics of a solar concentrator”, m.sc. thesis, texas tech university, 1984. [11] r. d. blevins, “flow-induced vibration”, second edition., kreiger, malibar, 1994. [12] j.a. peterka, n. hosoya, r.c. gee and d. kearney,” wind tunnel tests of parabolic trough solar collectors” national renewable energy laboratory, nrel/sr550-32282, may 2008. [13] garg. h. p. and prakash j., "solar energy fundamentals and applications", tata mcgraw-hill publishing company limited, tenth reprint, 2008. appedix1: details of numerical simulation parameters model geometry: parabolic trough solar collector boundary conditions: clumped-clumped for curved edges and free-free for straight edges. material: isotropic composite material with density (1455kg/m 3 ) and poisons ratio (0.38). governing equations: the equation of motion for free and forced vibration 1free vibration 𝑚 𝑥 + [𝑐] 𝑥 + [𝑘] 𝑥 = 0 2forced vibration 𝑚 𝑥 + [𝑐] 𝑥 + [𝑘] 𝑥 = 𝐹𝑜𝑠𝑖𝑛𝜔𝑡 where [m] : mass matrix 𝑥 : acceleration vector [c] : damping matrix 𝑥 : velocity vector [k]: stiffness matrix {x}: displacement matrix. the shell281 was used in current study. this element is suitable for analyzing thin to moderately-thick shell structures. the element has eight nodes with six degrees of freedom at each node: translations in the x, y, and z axes, and rotations about the x, y, and z-axes. fig. e1.1. showing element type. fig. e1.2. showing mashing model. (2014) 2538، صفحت 3، العذد10دجلت الخىارزهي الهنذسيت الوجلم عالء الذين عبذ القادر 38 دراست عوليت لتأثير انبثاق الذواهاث على كفاءة الوجوع الشوسي القادر كاظن عالء الذين عبذ خاوعح تغذاد / ي الهٍذسٍحولسه الشؤ aldina81@yahoo.com : االلىرشوًٌ الثشٌذ الخالصت ذٍاولد الذساسح ذأثٍش ذزتزب الهٍىك . أداا الىدىم الشىسً الىمىه تشىك المقم الىىافف عىمٍاًا دساسح ذأثٍش اٌثثاق الذواواخ عمى أخشٌد, الثحثفً هزا لذود و .الذساسح حساب أداا الىدىم تاسرخذان الىسة الحشاسي والىفااج الحشاسٌحوذضىٍد . الٍاذح عً اٌثثاق الذواواخ عمى ٌمماي وفااج أداا الىدىم ذأثٍشذضىً الثحث حساب الىسة الحشاسي والىفااج الحشاسٌح لمىدىم الشىسً وً لٍاساخ عىمٍح تذوي . الٍاذدح عً اٌثثاق الذواواخ عىمٍاًا إلثاسجاوحاواج ذأثٍش اٌثثاق الذواواخ عٍذ اٌضا ذٍاولد الذساسحو. ٌىىرج وً الىدىم الشىسً لهزا الغشضاذه ذمٍٍم وىا و. اٌثثاق الذواواخ ذأثٍشاٌثثاق الذواواخ وتىخىد ذه اٌداد. الى لٍه وخرمفح فً وعاوالخ الحىك الٍاذح عً الذواواخ ووزله ذشدد اٌثثالها اياي ذغٍٍش صواٌا الهدىن وسشعح الشٌاذ ذؤدي. ظشوف ذشغٍك وخرمفح طشٌمح العٍاصش الىحذدج لذساسح الىىاصفاخ الذٌٍاوٍىٍح لمىدىم اسرخذودوزله . الىدىم الشىسً وأدااالعاللح تًٍ الخىاص الذٌٍاوٍىٍح لمىدىم الشىسً . ئهن العاللح تًٍ السمىن الذٌٍاوٍىً لمىدىم وأداويالداٌة العىمً لرك فضال عًالشىسً mailto:aldina81@yahoo.comالبريد mailto:aldina81@yahoo.comالبريد al-khwarizmi engineering!!! journal al-khwarizmi engineering journal, vol. 6, no. 1, pp 14 -23 (2010) heat transfer of single and binary systems in pool boiling balasim a. abid abbas j. sultan* department of chemical engineering/ university of technology * email: abbasjawadsultan@yahoo.com (received 5 november 2008: accepted 9 november 2009) abstract the present research focuses on the study of the effect of mass transfer resistance on the rate of heat transfer in pool boiling. the nucleate pool boiling heat transfer coefficients for binary mixtures (ethanol-n-butanol, acetone-n-butanol, acetone-ethanol, hexane-benzene, hexane-heptane, and methanol-water) were measured at different concentrations of the more volatile components. the systems chosen covered a wide range of mixture behaviors. the experimental set up for the present investigation includes electric heating element submerged in the test liquid mounted vertically. thermocouple and a digital indictor measured the temperature of the heater surface. the actual heat transfer rate being obtained by multiplying the voltmeter and ammeter readings. a water cooled coil condenses the vapor produced by the heat input and the liquid formed returns to the cylinder for re-evaporation. the boiling results show that the nucleate pool boiling heat transfer coefficients of binary mixtures were always lower than the pure components nucleate pool boiling heat transfer coefficients. this confirmed that the mass transfer resistance to the movement of the more volatile component was responsible for decrease in heat transfer and that the maximum deterioration that was observed at a point was the absolute concentration differences between vapor and liquid phases at their maximum. all the data points were tested with the most widely known correlations namely those of calus-leonidopoulos, fujita and thome. it was found that thome's correlation is the more representative form, for it gave the least mean and standard deviations. keywords:pool , boiling , binary , systems. 1. introduction boiling heat transfer is defined as a mode of heat transfer, which occurs with a change in phase from liquid to vapor. there are two basic types of boiling: 1. pool boiling: where a heated surface is submerged below a free surface of liquid. 2. flow boiling: where the liquid is flowing on heated surface. pool and flow boiling are important in power industries and process industries. the present research focuses on pool boiling. [1] boiling of binary and multicomponent mixtures constitutes an important process in chemical process, air separation, refrigeration and many other industrial applications. reboilers feeding the vapors to distillation columns and flooded evaporators generally employ pool boiling, while the tube evaporation process involves flow boiling. although the multicomponent boiling is of greater interest from a process standpoint, fundamental understanding of the mechanism can be obtained first with binary mixtures.[2]. the objectives of the present study are to experimentally determine the nucleate pool boiling heat transfer coefficients of binary mixtures at different concentration of the more volatile components, and then the experimental results will be compared with famous correlations in pool boiling to examine the agreement with the experimental results and try to conclude a more representative correlation. balasim a. abid!!!! al-khwarizmi engineering journal, vol.6, no.1, pp 14 -23 (2010) 15 2. nucleate boiling studies for mixtures since the complexity of mixture boiling was recognized some years ago, a wealth of data giving nucleate boiling superheats and transfer coefficients has been published. according to grigorjev (1959) [3], the reduction in heat transfer is due to the increase of the bubble radial in equilibrium with the mixture, resulting in a smaller bubble population at the same degree of wall superheating. stephan and korner (1970) [4] found that the reversible isothermal work for a single bubble in equilibrium in mixture is greater than that needed for a pure component of the same physical properties. calus and leonidopoulos (1974) [5] showed results that approved the decrease in heat transfer coefficient up on the addition of npropanol to water, but an improvement in the heat transfer coefficient was recorded up on the addition of water to pure npropanol. 3. pool boiling models and correlations for binary mixtures the most popular empirical correlation for the prediction of boiling heat transfer coefficient is that of stephan and korner [7]. they suggested the use of an excess function formulation for determining the wall superheat and then the heat transfer coefficient in the boiling of binary mixtures. at a given heat flux, the wall superheat is provided by:  isatwsat tttt …(1) where the ideal super heat ∆ti (molar averaged value of the pure fluid wall superheats) is defined as 2111 )1( txtxti  …(2) where (x1) is the mole fraction of the more volatile component indicated with subscript (1), while the less volatile component is indicated with the subscript (2), and the excess superheat (∆θ) is calculated from: itxya  1 * 1 …(3) concluding that the energy required to form a vapor bubble in a binary mixture is a function of the mass driving force |y1 * x1|. in equation (3), (y1 *) is the equilibrium vapor mole fraction of the more volatile component and (a) is an empirical constant, different for every binary system, and is a function of pressure. the pressure influence was taken into account empirically in the range (0.1 – 1.0) mpa as:  paa 12.088.0   …(4) when (p) in bar, and (a0) is the value of (a) at (0.1) mpa the final expression of the correlation for heat transfer coefficient is   1 * 1 1 12.088.01 xypa h h    …(5) where (hi), the ideal heat transfer coefficient, is given by equation:  1221 21 hxhx hh hi   …(6) the correlation, tested on (357) data points, is reported in korner [8], thome [9], calus and leonidopoulos [5] and stephan and preusser [10]. calus and rice [11] were among the first investigators to develop an empirical model based on the bubble growth theories presented by scriven [12] and van stralen [13]. the term representing the reduction in bubble growth in binary systems was used to represent the reduction in heat transfer rate directly in pool boiling correlation. starting with term 1 1lg pl5.0 1 * 1 ) dx dt )( h c () d (xy1           , calus and rice empirically observed that it could be reduced to a simpler form,   15.0 1 * 1 )d/(xy1   while retaining the same functional dependence for isopropanol/ water, acetone/water, and water/glycerol mixtures. an exponent of (0.7) was added to this term as it provided a better match with the experimental data. the final expression of the correlation for heat transfer coefficient is: 7.0 1 * 1 5.0 1                xy d h h i  …(7) balasim a. abid!!!! al-khwarizmi engineering journal, vol.6, no.1, pp 14 -23 (2010) 16 since their method yields the pool boiling coefficients directly, it cannot utilize the more accurate pure component correlations. their model was unable to predict the severe suppression seen in their own experimental data. the first completely analytical expression for predicting the wall superheat / heat transfer coefficient was derived by calus and leonidopoulos [5]; the final correlation was given as: sndx dt h c d xy t t h h lg pi 1 1 1 1 5.0 1 * 1 1                                 …(8) where (sn) is the scriven number. the expression that multiplies (y1 *-x1) in equation (8) corresponds to the constant (a) in equation (3). contrary to constant (a), the expression:         ) dx dt )( h c () d ( 1lg pl5.0 …(9) is a function of the concentration of the binary mixture. although this model could not represent the effect of composition on heat transfer well, it provided a lower mean error than stephan and korner’s [7] and calus and rice’s [11] correlations. schlunder [14] introduced the difference between the saturation temperatures of the pure components at the same pressure as a parameter in his correlating scheme. also, a correction factor incorporating the mass transfer coefficient was introduced to modify stephan and korner's [5] correlation. the value of mass transfer coefficient was calculated. from experimental data, it was found to be in agreement with the values observed in the case of falling film evaporation. schlunder based his correlation on the film theory of mass transfer, assuming that: 1. the heat flow from the heated surface in nucleate boiling passes into the bubble in the form of latent heat. 2. the interfacial vapor-liquid mole fraction difference of the more volatile component is approximately equal to bulk difference. 3. the slope of the bubble point curve may be approximated by (tsat,2 – tsat,1). schlunder arrived at the equation:              lgll satsat ii h qb xytt q h h h  " 0 1 * 11,2," .exp1)()((1 …(10) where (hi) the ideal heat transfer coefficient is calculated from equation (6), and b0 is an empirical scaling factor set equal to (0.0002) m/s. thome [15] eliminated the two rough approximations adopted by schlunder calculating: 1. the exact expression for the vaporliquid mole fraction difference of the more volatile component at the interface. 2. the slope of the bubble point curve by the boiling range, i.e., the temperature difference between the dew point temperature and the bubble point temperature on the boiling curve (∆tbp): 1 * 1 bp 1 xy t dx dt    …(11) arriving at the correlation:          ) h qb .(exp1t q h 1 h h lgll " 0 bp" ii …(12) in the above correlation the boiling range has taken the place of the effective of the multicomponent temperature driving force across the diffusion shell in the schlunders correlation. wenzel et al. [16] followed a similar approach to schlunder [14], but they set out to obtain the actual value of the interface concentration by applying the mass transfer equation at the bubble boundary. this approach required knowledge of the mass transfer coefficient at the interface. it was empirically set at (10-4) m/s. the interface concentration was then used in determining the interface temperature. )tt)( q h (1 h h sats" i i   …(13)            lgllss s hb q xy xy 0 " ,1,1 1,1 …(14) where (hi) the ideal heat transfer coefficient is calculated from equation (6), and b0 =1 and βl= 10-4 m/s. balasim a. abid!!!! al-khwarizmi engineering journal, vol.6, no.1, pp 14 -23 (2010) 17 fujita et al [17] modified the fujita and tsutsui’s correlation by replacing the heat flux term with a term including the ideal wall superheat, ∆ti. ) t t (k1 h h i bp s i     …(15) 4. experimental work the pool-boiling unit is produced by p.a.hilton ltd.for pool boiling measurements with refrigerants, and it was modified during this study to be used with any other selected fluid. the experimental system is shown schematically in figure (1). fig.1. schematic diagram of the ُُُexperimental setup. 5. experimental procedure 1. the unit was charged with the test fluid until the level of the test fluid in the cylinder was (20 – 30) mm above the top of the heater. 2. the electric heater was adjusted to about (30) watts and the water flow rate was adjusted until the desired pressure was about (1atm) and then the voltage, current, vapor pressure, liquid temperature and metal temperature were observed. 3. the power was increased to (100) watts; and the cooling water flow rate was adjusted to give the desired pressure. when the test fluid started to boil vigorously the pressure release valve steam was pulled out to release any air in the cylinder. 4. when the test fluid reached saturation temperature and steady state conditions, the current, voltage, liquid temperature, and wall temperature were recorded. the power input was then increased at an equal intervals and the same operation was repeated and the systems studied the test fluids employed in the present study. the fluids were pure methanol, ethanol, acetone, nbutanol, heptane, n-hexane, benzene, water and various compositions of their binary mixtures. to see more details you can see reference [18]. 6. results and discussion 6.1. boiling of single component liquid measurements of the nucleate pool boiling heat transfer coefficients for pure acetone, benzene, ethanol, hexane, heptane, methanol, nbutanol, and water are made to provide a strong basis to analyze mixtures behaviour.some experimental tests were performed with pure water to ensure the reliability of the experimental test rig. fig.2. pool boiling curve for single components figure (2) shows the boiling curves of acetone, benzene, ethanol, hexane, heptane, methanol, nbutanol and water. it was found that the boiling curves of the pure liquids could never exceed that of the boiling curve of water and the arrangement of the boiling curves for different pure liquids in figure (2) are depend on the values of the nucleate 0 20 40 60 80 100 120 140 160 0.00 10.00 20.00 30.00 (tw-tsat)k q "( k w /m 2 ) pure w ater pure methanol pure heptane pure hexane pure benzene pure ethanol pure acetone pure butanol balasim a. abid!!!! al-khwarizmi engineering journal, vol.6, no.1, pp 14 -23 (2010) 18 boiling heat transfer coefficients which dependent on physical properties (kl, cp, ρl, σ, μl, ∆hlg, ρv) and temperature difference (which is wall temperature minus the liquid saturation temperature ) for pure liquids so that the pure water has larger values of nucleate boiling heat transfer coefficients than that for pure liquids because pure water has high values of thermal conductivity, liquid density and specific heat as compared with the pure liquids. fig.3. variation of boiling heat transfer coefficient with heat flux for single components. figure (3) shows the nucleate boiling heat transfer coefficients for pure liquids (acetone, benzene, ethanol, hexane, heptane, methanol, nbutanol and water) as a function of heat fluxes. it was found that the nucleate pool boiling heat transfer coefficients for pure liquids increases with increasing heat fluxes because of the higher number of bubbles generated as flux increases. 6.2. boiling of binary mixtures the nucleate pool boiling heat transfer coefficient data for four different compositions (0.2, 0.4, 0.6, and 0.8) of the more volatile components, aqueous mixture of methanol and the nonaqueous mixtures of acetone-ethanol, acetone-n-butanol, ethanol-n-butanol, hexanebenzene and methanol-water . figure (4) shows the boiling curve for ethanoln-butanol mixture at different compositions of the more volatile component (ethanol).it was found that the temperature difference for ethanol-nbutanol mixture was larger than that for pure components constituting the mixture because of the increase wall superheat required to activate bubble nucleation centers for mixtures, resulting in less-dense bubble population at a given wall superheat as compared with that for pure liquids. fig.4 pool boiling curve for ethanol n-butanol. so it was found the arrangement of the boiling curves at different compositions of the ethanol-nbutanol mixtures are very dependent on mass driving force (y*-x) so that the last boiling curve was (0.4) mole fraction of ethanol-n-butanol mixture because at this compositions the binary system of ethanol-n-butanol has the largest value of (y*-x). the larger value of (y*-x) is expected to exert a strong mixture effect on the boiling heat transfer, since mass transfer resistance leads to the loss of wall superheat. fig.5. pool boiling curve for acetonen-butanol. figure (5) shows the boiling curve for acetonen-butanol mixture at different compositions of the more volatile component (acetone).it was found that the temperature difference for acetone-nbutanol mixture was larger than that for pure components constituting the mixture and was found that the last boiling curve was (0.2) mole fraction of acetone-n-butanol mixture because at 0 20 40 60 80 100 120 140 160 0.00 10.00 20.00 30.00 40.00 (tw-tsat)k q "( kw /m 2 ) pure n-butanol 0.2 acetone 0.6 acetone 0.8 acetone pure acetone 0 1 2 3 4 5 6 7 8 9 0 50 100 150 q" (kw/m2) h ( k w /m 2 k ) pure w ater pure methanol pure heptane pure hexane pure benzene pure ethanol pure acetone pure n-butanol 0 20 40 60 80 100 120 140 160 0.00 10.00 20.00 30.00 40.00 (tw-tsat)k q "( k w /m 2 ) pure n-butano l 0.2 ethanol 0.4 ethanol 0.6 ethanol 0.8 ethanol pure ethanol balasim a. abid!!!! al-khwarizmi engineering journal, vol.6, no.1, pp 14 -23 (2010) 19 this compositions the binary system of acetone-nbutanol has the largest value of mass driving force (y*-x) which leads to the loss of wall superheat. the rest of the systems (acetone-etanol, hexane-benzene, hexane-heptane and methanolwater) has the same boiling curve behavior. in binary mixtures the temperature difference is always larger than that for pure component. this can be explained as follows: in bubble growth dynamics, it is usually assumed that a temperature gradient exists between the superheated solid surface and liquid-vapor interface and the heat required for vapor generation is supplied by the heat conducted across the temperature gradient. thus, for pure fluids, the bubble growth rate is limited by the rate of heat conduction. in addition, another limitation exists during the bubble growth of mixtures. the difference in volatilities of the two components causes a stripping of the more volatile component near the interface. thus, the mole fraction of the more volatile component of the liquid at the interface is smaller than that in the bulk, resulting in an increase in the saturation temperature at the interface. this phenomenon, consequently, reduces the available effective driving temperature potential for the supply of heat for bubble generation. figures (6 7) show the nucleate pool boiling heat transfer coefficients for two binary mixtures (ethanol-n-butanol, acetone-n-butanol). as function of heat fluxes at different composition of the more volatile component. it was found that the nucleate pool boiling heat transfer coefficients of either the pure liquids or binary mixture increased with rising the heat flux because of the large number of small bubbles generated on the surface of heater as heat flux increases, and because of a generally higher nucleate pool boiling heat transfer coefficients. so it was found that the smallest values of nucleate pool boiling heat transfer coefficients for six binary mixtures were at maximum difference of (y*-x) because of the maximum reduction in bubble growth rate occurs at a maximum value of (y*-x). this lead to conclude that temperature difference required to form a vapor bubble in a binary mixture is the function of the mass transfer driving force (y*-x). for a given heat flux, the heat transfer coefficients of the mixtures are lower than the values obtained by the pure components constituting the mixture. this is due to the utilization of part of the temperature driving force to overcome the mass transfer resistance caused by diffusion of the light components to the bubble interface. therefore, to obtain a given heat flux, an additional temperature driving force is required for binary mixtures; hence the heat transfer coefficients are lower than those of constituent pure components. the rest of the systems (acetone-ethanol, hexane-benzene, hexane-heptane and methanolwater) has the same behavior. fig.6. variation of boiling heat transfer coefficient with heat flux for ethanol nbutanol. fig.7. variation of boiling heat transfer coefficient with heat flux for acetone-nbutanol. figures (8 9) show the nucleate pool boiling heat transfer coefficients for two binary mixtures (ethanol-n-butanol, acetonen-butanol) as function of the mole fraction of the more volatile component at different heat fluxes. it was found that the nucleate pool boiling heat transfer coefficients for six 0 1 2 3 4 5 6 7 8 0 50 100 150 q" (kw/m2) h ( kw /m 2 k ) pure n-butanol 0.2 ethanol 0.4 ethanol 0.6 ethanol 0.8 ethanol pure ethanol 0 1 2 3 4 5 6 7 8 9 0 50 100 150 q" (kw/m2) h ( kw /m 2 k ) pure n-butanol 0.2 acetone 0.6 acetone 0.8 acetone pure acetone balasim a. abid!!!! al-khwarizmi engineering journal, vol.6, no.1, pp 14 -23 (2010) 20 binary mixtures were always lower than that of the nucleate pool boiling heat transfer coefficients for the pure liquids. this confirmed that the mass transfer resistance to the movement of the more volatile component was responsible for the decrease in heat transfer coefficient for binary mixture and also the significant change in the physical properties of the mixture and the effect of composition on nucleation of bubbles in binary mixture were also responsible for the decrease in heat transfer coefficiet for binary mixture. the rest of the systems (acetoneethanol, hexane-benzene, hexane-heptane and methanol-water) has the same behavior. an interesting point is that the maximum deterioration was observed at the concentrations where the absolute concentration differences between vapor and liquid phase were also maximum(y*-x). fig.8. variation of boiling heat transfer coefficient with composition for ethanol -nbutanol. the following is an explanation for this heat transfer deterioration. the bubbles leaving the heated surface are enriched in the volatile component (i.e. lower boiling point component). this results in a reduction of this particular component in the boiling boundary layer in the vicinity of the heated surface. the liquid mole fraction of the volatile component in this layer is therefore lower than that in the bulk liquid. consequently, the boiling temperature in the layer becomes higher than that in the bulk liquid. this can be deduced from a vapor. liquid phase equilibrium diagram of typical binary mixture. for nucleate pool boiling, the heat transfer coefficient is a function of the wall superheat, i.e. the difference between the wall temperature and the liquid boiling temperature. for the determination of this heat transfer coefficient for a binary mixture, the measured wall superheat (based on bulk liquid boiling temperature) is used; whilst the wall superheat in the boiling boundary layer is driving the flow of heat in the latter is smaller than that in the former. fig.9. variation of boiling heat transfer coefficient with composition for acetone-nbutanol. 6.3. testing of experimental results with correlations when designing the evaporator of an aqueous system or non-a aqueous system or refrigeration system, one must be able to accurately predict the boiling heat transfer coefficients of these systems used and heat flux predictions of mixtures are of interest in some cases of evaporator design and also in cryogenics, rocketry and power system design. so a suitable correlation for thermal design must be concluded. the experimental results were tested with three correlations. the first of these was proposed by calus and leonidopoulos [5] the second correlation was proposed by thome [15] the third correlation was proposed by fujita et al [17] the mean deviations and standard deviations were determined for their correlations. figures (10–11) for each binary system measured. 0 1 2 3 4 5 6 7 8 0 0.2 0.4 0.6 0.8 1 x ethanol h ( k w /m 2 k ) q"=133.38 (kw/m2) q"=115.08 (kw/m2) q"=95.46 (kw/m2) q"=77.09 (kw/m2) q"=60.68 (kw/m2) q"=45.77 (kw/m2) 0 1 2 3 4 5 6 7 8 9 0 0.2 0.4 0.6 0.8 1 x acetone h ( k w /m 2 k ) q"=133.38 (kw /m2) q"=115.08 (kw /m2) q"=95.46 (kw /m2) q"=77.09 (kw /m2) q"=60.68 (kw /m2) q"=45.77 (kw /m2) balasim a. abid!!!! al-khwarizmi engineering journal, vol.6, no.1, pp 14 -23 (2010) 21 by comparing the mean deviation and standard deviations for three correlations. it was concluded that thome’s correlation represented the experimental results better than the others, although both correlations were found to be in good agreement with the data. the mean deviation for thome's correlation was (4.968%) for six binary mixtures while it was (7.713%) for fujita's correlation and it was (9.814%) for calus and leonidopoulos correlation. from these we conclude that thome’s correlation is suitable for general thermal design use since it gives good agreements with experimental data and it is directly applicable to multicomponent mixtures, and it requires a minimum of phase equilibrium data, and it is applicable at high reduced pressures. fig.10. comparison of experimental results with three correlations for ethanol-nbutanol at q" = 115.08(kw/m2). fig.11. comparison of experimental results with three correlations for acetone-nbutanol at q" = 115.08(kw/m2) pool boiling experiments were carried out on boiling of pure and binary mixtures in which the nucleate pool boiling heat transfer coefficients were measured for pure and binary mixtures at atmospheric pressure at which heat fluxes varied up to (133.38) kw/m2. the following conclusions can be reached from an analysis of the experimental data. 1. for a given heat flux, the heat transfer coefficients of mixtures are lower than the values obtained by the pure components constituting the mixture. 2. it was noticed from the present study that the heat transfer coefficient is a function of the difference between the equilibrium vapor and liquid concentration, (y*-x) of the light component and the minimum heat transfer coefficient occurs at the maximum of (y*-x) of the light component. 3. the boiling heat transfer coefficients for either the pure liquids or the binary mixtures increased with the rising heat flux at constant pressure. 4. the data of binary mixtures were compared with three correlations. thome’s correlation yielded a smaller mean deviation than that of fujita and calus and leonidopoulos’ correlation. they compared their correlation with several data sets from literature as well as with their own experimental results. the mean deviation between the predicted and experimental values ranged between (3.6) and (14) percent. to see more models you can see reference [18]. nomenclatures a0 parameter defined in equation (1.4) cp specific heat d mass diffusivity d0 12, d0 21 diffusion coefficient of component 1(2) present in infinitely low concentration of liquid mixture fd diffusion factor g parameter defined as:g=(x1-x1,s)/(y1,s-x1,s) h heat transfer coefficient k thermal conductivity lm mass diffusion shell thickness lt thermal boundary layer thickness 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500 7000 7500 0 0.2 0.4 0.6 0.8 1 w acetone h ( k w /m 2 k ) h experimental h fujita h thome h calus 3000 3500 4000 4500 5000 5500 6000 6500 7000 0 0.2 0.4 0.6 0.8 1 w ethanol h ( k w /m 2 k ) h experimental h fujita h thome h calus balasim a. abid!!!! al-khwarizmi engineering journal, vol.6, no.1, pp 14 -23 (2010) 22 m molecular weight nu nusselt number [hd/k] p pressure pc critical pressure pr prandtl number [cp μ /k] q" heat flux sn scriven number, defined as: t temperature tw wall temperature tsat saturation temperature v1 volatility parameter, defined by equation (1.24) x mole fraction of the more volatile component y* equilibrium vapor mole fraction greek symbols α thermal diffusivity ∆hlg latent heat of vaporization ∆tbp boiling range ∆teff effective superheat ∆tsat wall superheat [tw – tsat] ∆t1, ∆t2 wall superheat for component (1) and (2) in pool boiling μ viscosity ρ density σ surface tension 7. references [1] coulson, j.m., and richardson, j.f: chemical engineering, vol.1, bath press co.ltd., great britain, 5th edition (1993). [2] van wijk, w.r, vos, a.s., and van stralen, s.j.d: heat transfer to boiling binary liquid mixtures, chem.eng.sci, vol.5, pp.65-80 (1956). [3] grigorev, l.n.: studies of heat transfer of two component mixtures, teplo i masso perenos, no.2, pp.120-127 (1962). [4] stephan, k., korner, m.: heat transfer in boiling mixtures, proceedings of the 7th, heat transferconf., paper rk14, pp.59-81(1982). [5] calus, w.f., and leonidopoulos: pool boiling of binary liquid mixtures, int.j.heat mass transfer, vol.17, pp.249-246 (1974). [6] thome, j.r.: latent and sensible heat transfer rates in the boiling of binary mixtures, 20th edition. joint asme/aiche national heat transfer conference, milwaukee, wisconsin, also asme, pp.81ht-28 (1981). [7] stephan, k., and korner, m.: calculation of heat transfer in evaporating binary liquid mixtures, chem.ing.tech.vol.41, pp.409-417 (1969). [8] korner, m.: beitrag zum warmeubergang beider blasenverdampfung binarer gemishe, ph.d.thesis, technical university of aachen (1967). [9] thome, j.r.: prediction of binary mixture boiling heat transfer coefficients using only phase equilibrium data, int.j.heat mass transfer, vol.26, pp.965-974 (1983). [10] stephen, k., and preusser, p.: heat transfer and critical heat flux in pool boiling of binary and ternary mixture, ger.chem.eng.vol.2, pp. 161 – 169 (1979). [11] calus, w.f., and rice, p.: pool boiling binary liquid mixtures, chem.eng.sci.vol.27, pp. 1687 – 1697 (1972). [12] scriven, l.e.: on the dynamics of phase growth, chem.eng.sci.vol.10, pp.1-13 (1959). [13] van stralen, s.: the mechanism of nucleate boiling in pure liquids and binary mixtures, int.j.heat mass transfer, pp.990 – 1046, 1469 – 1498(1967). [14] schlunder, e.u.: heat transfer in nucleate pool boiling of mixtures, proc.7th edition, int.heat transfer conf., vol.4, pp.20732079 (1982). [15] thome, j.r.: prediction of binary mixture boiling heat transfer coefficient using only phase equilibrium data, int.j. heat mass transfer, vol.26, pp. 965-974(1983). [16] wenzel, u., balzer, f., jamialahmadi, m., and mullersteinhagen, h.: pool boiling heat transfer coefficients for binary mixture of acetone, isopropanol, and water, heat tran.eng. vol.16, pp. 36 – 43 (1995). [17] fujita, y., bai, q., and tsutsui, m.: heat transfer of binary mixtures in nucleate pool boiling, 2 nd eur.thermi.and 14 thuit nat. heat trans. (1996), internet. [18] sultan,a.j, heat transfer of single and binary systems in pool boiling.m.sc thesis universityoftechnology,2006. )2010( 23 14، صفحة1، العدد 6مجلة الخوارزمي الھندسیة المجلد عبد احمد بالسم 23 الماء المنتج من الحقول النفطیة ومعالجات عباس جواد سلطان عبداحمد بالسم الجامعة التكنولوجیة / الھندسة الكیمیائیة قسم الخالصة ي ان الحوض ي الغلی رارة ف ال الح دل انتق ى مع ة عل ال الكتل ة انتق أثیر مقاوم ة ت ى دراس ال .یركز البحث عل امالت انتق ط مع وي للخالئ ان المتن رارة للغلی ح ة انول(الثنائی انول -ایث یتون,بیوت انول-اس یتون,بیوت انول-اس ان,ایث زین-ھكس ان,بن ان-ھكس انول,ھیبت اء-میث ر ) م ادة االكث ز للم ف التراكی د مختل ھا عن م قیاس ت .االنظمة المختارة غطت مدى واسع من تصرفات المحالیل.تطایرا ودي یتضمن الجھاز المستخدم في ال كل عم ب بش رارة . بحث على مسخن كھربائي مغمور في سائل االختبار ومرك ة ح م درج ائي ت خن الكھرب طح المس س ر .قیاسھا بواسطة متحسس حراري مربوط بمؤشر رقمي ي االمیت ولتمیتر ف راءة الف رب ق د .معدل االنتقال الحراري الحقیقي تم الحصول علیھ من حاصل ض وق .واسطة الحرارة المتولدة من المسخن الكھربائي واعادةالسائل المتكون الى االسطوانة الزجاجیة لیتم اعادة تبخیرهاستخدم مكثف للبخار الناتج ب ة لقد بینت نتائج الغلیان بأن معامالت ان وائل النقی رارة للس ال الح امالت انتق ن مع د .تقال الحرارة للغلیان المتنوي للمزیج الثنائي تكون دائما اقل م ذا یؤك وھ ائ زیج الثن رارة للم ال الح امالت انتق ي مع ان ف ر النقص لوك یفس ي بأن انتقال الكتلة یقاوم حركة المادة االكثر تطایرا في المحلول وھذا الس دھور ف ر ت ي وان اكب .عدالت انتقال الحرارة لوحظ عندما یكون مطلق الفرق بین تركیز البخار والسائل للمادة االكثر تطایرا اكبر مایمكنم تعطي اكثر ) توم(وقد وجد ان عالقة ) توم,فوجیتا, كیلس ولینودوبلس(النتائج التجریبیة تم اختبارھا مع اكثر العالقات شھرة وھي بالتحدید عالقات .ئج المختبریة النھا تعطي اقل معدل انحراف واقل انحراف معیاري من العالقتین السابقتینتمثیال للنتا 0 20 40 60 80 100 120 140 160 0.0010.0020.0030.00 (t w -t sat )k q "( kw / m 2 ) pure water pure methanol pure heptane pure hexane pure benzene pure ethanol pure acetone pure butanol 0 1 2 3 4 5 6 7 8 9 050100150 q" (kw/m 2 ) h ( kw / m 2 k ) pure water pure methanol pure heptane pure hexane pure benzene pure ethanol pure acetone pure n-butanol 0 1 2 3 4 5 6 7 8 050100150 q" (kw/m2) h (kw/m 2 k) pure n-butanol 0.2 ethanol 0.4 ethanol 0.6 ethanol 0.8 ethanol pure ethanol q d + d = = d i sat w sat t t t t 2 1 1 1 ) 1 ( t x t x t i d + d = d i t x y a d = d 1 * 1 q ( ) p a a 12 . 0 88 . 0 + = ° ( ) [ ] 1 * 1 1 12 . 0 88 . 0 1 x y p a h h + + = ° ( ) 1 2 2 1 2 1 h x h x h h h i + = 1 1 lg pl 5 . 0 1 * 1 ) dx dt )( h c ( ) d ( x y 1 ú û ù ê ë é d a + [ ] 1 5 . 0 1 * 1 ) d / ( x y 1 a + 7 . 0 1 * 1 5 . 0 1 ú ú û ù ê ê ë é ÷ ø ö ç è æ + = x y d h h i a sn dx dt h c d x y t t h h lg p i 1 1 1 1 5 . 0 1 * 1 1 = ú ú û ù ê ê ë é ÷ ÷ ø ö ç ç è æ ÷ ÷ ø ö ç ç è æ d ÷ ø ö ç è æ + = d d = a ú û ù ê ë é d a ) dx dt )( h c ( ) d ( 1 lg pl 5 . 0 ( ) ) ú ú û ù ê ê ë é d + = lg l l sat sat i i h q b x y t t q h h h b r " 0 1 * 1 1 , 2 , " . exp 1 )( )( ( 1 1 * 1 bp 1 x y t dx dt d = ú û ù ê ë é d b r d + = ) h q b .( exp 1 t q h 1 h h lg l l " 0 bp " i i ) t t )( q h ( 1 h h sat s " i i + = ú û ù ê ë é d = lg l l s s s h b q x y x y r b 0 " , 1 , 1 1 , 1 ) t t ( k 1 h h i bp s i d d + = 0 20 40 60 80 100 120 140 160 0.0010.0020.0030.0040.00 (t w -t sat )k q"(kw/m 2 ) pure n-butano l 0.2 ethanol 0.4 ethanol 0.6 ethanol 0.8 ethanol pure ethanol 0 1 2 3 4 5 6 7 8 00.20.40.60.81 x ethanol h ( kw / m 2 k ) q"=133.38 (kw/m2) q"=115.08 (kw/m2) q"=95.46 (kw/m2) q"=77.09 (kw/m2) q"=60.68 (kw/m2) q"=45.77 (kw/m2) 0 1 2 3 4 5 6 7 8 9 00.20.40.60.81 x acetone h ( kw / m 2 k ) q"=133.38 (kw/m2) q"=115.08 (kw/m2) q"=95.46 (kw/m2) q"=77.09 (kw/m2) q"=60.68 (kw/m2) q"=45.77 (kw/m2) 3000 3500 4000 4500 5000 5500 6000 6500 7000 00.20.40.60.81 w ethanol h ( kw / m 2 k ) h experimental h fujita h thome h calus 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500 7000 7500 00.20.40.60.81 acetone h ( kw / m 2 k ) h experimental h fujita h thome h calus 0 20 40 60 80 100 120 140 160 0.0010.0020.0030.0040.00 (t w -t sat )k q"(kw/m 2 ) pure n-butanol 0.2 acetone 0.6 acetone 0.8 acetone pure acetone 0 1 2 3 4 5 6 7 8 9 050100150 q" (kw/m 2 ) h (kw/m 2 k) pure n-butanol 0.2 acetone 0.6 acetone 0.8 acetone pure acetone balasim a. abid al-khwarizmi engineering journal, vol.6, no.1, pp 14 -23 (2010) al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 6, no. 1, pp 14 -23 (2010) heat transfer of single and binary systems in pool boiling balasim a. abid abbas j. sultan* department of chemical engineering/ university of technology * email: abbasjawadsultan@yahoo.com (received 5 november 2008: accepted 9 november 2009) abstract the present research focuses on the study of the effect of mass transfer resistance on the rate of heat transfer in pool boiling. the nucleate pool boiling heat transfer coefficients for binary mixtures (ethanol-n-butanol, acetone-n-butanol, acetone-ethanol, hexane-benzene, hexane-heptane, and methanol-water) were measured at different concentrations of the more volatile components. the systems chosen covered a wide range of mixture behaviors. the experimental set up for the present investigation includes electric heating element submerged in the test liquid mounted vertically. thermocouple and a digital indictor measured the temperature of the heater surface. the actual heat transfer rate being obtained by multiplying the voltmeter and ammeter readings. a water cooled coil condenses the vapor produced by the heat input and the liquid formed returns to the cylinder for re-evaporation. the boiling results show that the nucleate pool boiling heat transfer coefficients of binary mixtures were always lower than the pure components nucleate pool boiling heat transfer coefficients. this confirmed that the mass transfer resistance to the movement of the more volatile component was responsible for decrease in heat transfer and that the maximum deterioration that was observed at a point was the absolute concentration differences between vapor and liquid phases at their maximum. all the data points were tested with the most widely known correlations namely those of calus-leonidopoulos, fujita and thome. it was found that thome's correlation is the more representative form, for it gave the least mean and standard deviations. keywords:pool , boiling , binary , systems. 1. introduction boiling heat transfer is defined as a mode of heat transfer, which occurs with a change in phase from liquid to vapor. there are two basic types of boiling: 1. pool boiling: where a heated surface is submerged below a free surface of liquid. 2. flow boiling: where the liquid is flowing on heated surface. pool and flow boiling are important in power industries and process industries. the present research focuses on pool boiling. [1] boiling of binary and multicomponent mixtures constitutes an important process in chemical process, air separation, refrigeration and many other industrial applications. reboilers feeding the vapors to distillation columns and flooded evaporators generally employ pool boiling, while the tube evaporation process involves flow boiling. although the multicomponent boiling is of greater interest from a process standpoint, fundamental understanding of the mechanism can be obtained first with binary mixtures.[2]. the objectives of the present study are to experimentally determine the nucleate pool boiling heat transfer coefficients of binary mixtures at different concentration of the more volatile components, and then the experimental results will be compared with famous correlations in pool boiling to examine the agreement with the experimental results and try to conclude a more representative correlation. 2. nucleate boiling studies for mixtures since the complexity of mixture boiling was recognized some years ago, a wealth of data giving nucleate boiling superheats and transfer coefficients has been published. according to grigorjev (1959) [3], the reduction in heat transfer is due to the increase of the bubble radial in equilibrium with the mixture, resulting in a smaller bubble population at the same degree of wall superheating. stephan and korner (1970) [4] found that the reversible isothermal work for a single bubble in equilibrium in mixture is greater than that needed for a pure component of the same physical properties. calus and leonidopoulos (1974) [5] showed results that approved the decrease in heat transfer coefficient up on the addition of npropanol to water, but an improvement in the heat transfer coefficient was recorded up on the addition of water to pure npropanol. 3. pool boiling models and correlations for binary mixtures the most popular empirical correlation for the prediction of boiling heat transfer coefficient is that of stephan and korner [7]. they suggested the use of an excess function formulation for determining the wall superheat and then the heat transfer coefficient in the boiling of binary mixtures. at a given heat flux, the wall superheat is provided by: …(1) where the ideal super heat ∆ti (molar averaged value of the pure fluid wall superheats) is defined as …(2) where (x1) is the mole fraction of the more volatile component indicated with subscript (1), while the less volatile component is indicated with the subscript (2), and the excess superheat (∆θ) is calculated from: …(3) concluding that the energy required to form a vapor bubble in a binary mixture is a function of the mass driving force |y1* x1|. in equation (3), (y1*) is the equilibrium vapor mole fraction of the more volatile component and (a) is an empirical constant, different for every binary system, and is a function of pressure. the pressure influence was taken into account empirically in the range (0.1 – 1.0) mpa as: …(4) when (p) in bar, and (a0) is the value of (a) at (0.1) mpa the final expression of the correlation for heat transfer coefficient is …(5) where (hi), the ideal heat transfer coefficient, is given by equation: …(6) the correlation, tested on (357) data points, is reported in korner [8], thome [9], calus and leonidopoulos [5] and stephan and preusser [10]. calus and rice [11] were among the first investigators to develop an empirical model based on the bubble growth theories presented by scriven [12] and van stralen [13]. the term representing the reduction in bubble growth in binary systems was used to represent the reduction in heat transfer rate directly in pool boiling correlation. starting with term , calus and rice empirically observed that it could be reduced to a simpler form, while retaining the same functional dependence for isopropanol/ water, acetone/water, and water/glycerol mixtures. an exponent of (0.7) was added to this term as it provided a better match with the experimental data. the final expression of the correlation for heat transfer coefficient is: …(7) since their method yields the pool boiling coefficients directly, it cannot utilize the more accurate pure component correlations. their model was unable to predict the severe suppression seen in their own experimental data. the first completely analytical expression for predicting the wall superheat / heat transfer coefficient was derived by calus and leonidopoulos [5]; the final correlation was given as: …(8) where (sn) is the scriven number. the expression that multiplies (y1*-x1) in equation (8) corresponds to the constant (a) in equation (3). contrary to constant (a), the expression: …(9) is a function of the concentration of the binary mixture. although this model could not represent the effect of composition on heat transfer well, it provided a lower mean error than stephan and korner’s [7] and calus and rice’s [11] correlations. schlunder [14] introduced the difference between the saturation temperatures of the pure components at the same pressure as a parameter in his correlating scheme. also, a correction factor incorporating the mass transfer coefficient was introduced to modify stephan and korner's [5] correlation. the value of mass transfer coefficient was calculated. from experimental data, it was found to be in agreement with the values observed in the case of falling film evaporation. schlunder based his correlation on the film theory of mass transfer, assuming that: 1. the heat flow from the heated surface in nucleate boiling passes into the bubble in the form of latent heat. 2. the interfacial vapor-liquid mole fraction difference of the more volatile component is approximately equal to bulk difference. 3. the slope of the bubble point curve may be approximated by (tsat,2 – tsat,1). schlunder arrived at the equation: …(10) where (hi) the ideal heat transfer coefficient is calculated from equation (6), and b0 is an empirical scaling factor set equal to (0.0002) m/s. thome [15] eliminated the two rough approximations adopted by schlunder calculating: 1. the exact expression for the vaporliquid mole fraction difference of the more volatile component at the interface. 2. the slope of the bubble point curve by the boiling range, i.e., the temperature difference between the dew point temperature and the bubble point temperature on the boiling curve (∆tbp): …(11) arriving at the correlation: …(12) in the above correlation the boiling range has taken the place of the effective of the multi-component temperature driving force across the diffusion shell in the schlunders correlation. wenzel et al. [16] followed a similar approach to schlunder [14], but they set out to obtain the actual value of the interface concentration by applying the mass transfer equation at the bubble boundary. this approach required knowledge of the mass transfer coefficient at the interface. it was empirically set at (10-4) m/s. the interface concentration was then used in determining the interface temperature. …(13) …(14) where (hi) the ideal heat transfer coefficient is calculated from equation (6), and b0 =1 and βl= 10-4 m/s. fujita et al [17] modified the fujita and tsutsui’s correlation by replacing the heat flux term with a term including the ideal wall superheat, ∆ti. …(15) 4. experimental work the pool-boiling unit is produced by p.a.hilton ltd.for pool boiling measurements with refrigerants, and it was modified during this study to be used with any other selected fluid. the experimental system is shown schematically in figure (1). fig.1. schematic diagram of the ُُُexperimental setup. 5. experimental procedure 1. the unit was charged with the test fluid until the level of the test fluid in the cylinder was (20 – 30) mm above the top of the heater. 2. the electric heater was adjusted to about (30) watts and the water flow rate was adjusted until the desired pressure was about (1atm) and then the voltage, current, vapor pressure, liquid temperature and metal temperature were observed. 3. the power was increased to (100) watts; and the cooling water flow rate was adjusted to give the desired pressure. when the test fluid started to boil vigorously the pressure release valve steam was pulled out to release any air in the cylinder. 4. when the test fluid reached saturation temperature and steady state conditions, the current, voltage, liquid temperature, and wall temperature were recorded. the power input was then increased at an equal intervals and the same operation was repeated and the systems studied the test fluids employed in the present study. the fluids were pure methanol, ethanol, acetone, nbutanol, heptane, n-hexane, benzene, water and various compositions of their binary mixtures. to see more details you can see reference [18]. 6. results and discussion 6.1. boiling of single component liquid measurements of the nucleate pool boiling heat transfer coefficients for pure acetone, benzene, ethanol, hexane, heptane, methanol, n-butanol, and water are made to provide a strong basis to analyze mixtures behaviour.some experimental tests were performed with pure water to ensure the reliability of the experimental test rig. fig.2. pool boiling curve for single components figure (2) shows the boiling curves of acetone, benzene, ethanol, hexane, heptane, methanol, n-butanol and water. it was found that the boiling curves of the pure liquids could never exceed that of the boiling curve of water and the arrangement of the boiling curves for different pure liquids in figure (2) are depend on the values of the nucleate boiling heat transfer coefficients which dependent on physical properties (kl, cp, ρl, σ, μl, ∆hlg, ρv) and temperature difference (which is wall temperature minus the liquid saturation temperature ) for pure liquids so that the pure water has larger values of nucleate boiling heat transfer coefficients than that for pure liquids because pure water has high values of thermal conductivity, liquid density and specific heat as compared with the pure liquids. fig.3. variation of boiling heat transfer coefficient with heat flux for single components. figure (3) shows the nucleate boiling heat transfer coefficients for pure liquids (acetone, benzene, ethanol, hexane, heptane, methanol, n-butanol and water) as a function of heat fluxes. it was found that the nucleate pool boiling heat transfer coefficients for pure liquids increases with increasing heat fluxes because of the higher number of bubbles generated as flux increases. 6.2. boiling of binary mixtures the nucleate pool boiling heat transfer coefficient data for four different compositions (0.2, 0.4, 0.6, and 0.8) of the more volatile components, aqueous mixture of methanol and the nonaqueous mixtures of acetone-ethanol, acetone-n-butanol, ethanol-n-butanol, hexane-benzene and methanol-water . figure (4) shows the boiling curve for ethanol-n-butanol mixture at different compositions of the more volatile component (ethanol).it was found that the temperature difference for ethanol-n-butanol mixture was larger than that for pure components constituting the mixture because of the increase wall superheat required to activate bubble nucleation centers for mixtures, resulting in less-dense bubble population at a given wall superheat as compared with that for pure liquids. fig.4 pool boiling curve for ethanol n-butanol. so it was found the arrangement of the boiling curves at different compositions of the ethanol-n-butanol mixtures are very dependent on mass driving force (y*-x) so that the last boiling curve was (0.4) mole fraction of ethanol-n-butanol mixture because at this compositions the binary system of ethanol-n-butanol has the largest value of (y*-x). the larger value of (y*-x) is expected to exert a strong mixture effect on the boiling heat transfer, since mass transfer resistance leads to the loss of wall superheat. fig.5. pool boiling curve for acetonen-butanol. figure (5) shows the boiling curve for acetone-n-butanol mixture at different compositions of the more volatile component (acetone).it was found that the temperature difference for acetone-n-butanol mixture was larger than that for pure components constituting the mixture and was found that the last boiling curve was (0.2) mole fraction of acetone-n-butanol mixture because at this compositions the binary system of acetone-n-butanol has the largest value of mass driving force (y*-x) which leads to the loss of wall superheat. the rest of the systems (acetone-etanol, hexane-benzene, hexane-heptane and methanol-water) has the same boiling curve behavior. in binary mixtures the temperature difference is always larger than that for pure component. this can be explained as follows: in bubble growth dynamics, it is usually assumed that a temperature gradient exists between the superheated solid surface and liquid-vapor interface and the heat required for vapor generation is supplied by the heat conducted across the temperature gradient. thus, for pure fluids, the bubble growth rate is limited by the rate of heat conduction. in addition, another limitation exists during the bubble growth of mixtures. the difference in volatilities of the two components causes a stripping of the more volatile component near the interface. thus, the mole fraction of the more volatile component of the liquid at the interface is smaller than that in the bulk, resulting in an increase in the saturation temperature at the interface. this phenomenon, consequently, reduces the available effective driving temperature potential for the supply of heat for bubble generation. figures (6 7) show the nucleate pool boiling heat transfer coefficients for two binary mixtures (ethanol-n-butanol, acetone-n-butanol). as function of heat fluxes at different composition of the more volatile component. it was found that the nucleate pool boiling heat transfer coefficients of either the pure liquids or binary mixture increased with rising the heat flux because of the large number of small bubbles generated on the surface of heater as heat flux increases, and because of a generally higher nucleate pool boiling heat transfer coefficients. so it was found that the smallest values of nucleate pool boiling heat transfer coefficients for six binary mixtures were at maximum difference of (y*-x) because of the maximum reduction in bubble growth rate occurs at a maximum value of (y*-x). this lead to conclude that temperature difference required to form a vapor bubble in a binary mixture is the function of the mass transfer driving force (y*-x). for a given heat flux, the heat transfer coefficients of the mixtures are lower than the values obtained by the pure components constituting the mixture. this is due to the utilization of part of the temperature driving force to overcome the mass transfer resistance caused by diffusion of the light components to the bubble interface. therefore, to obtain a given heat flux, an additional temperature driving force is required for binary mixtures; hence the heat transfer coefficients are lower than those of constituent pure components. the rest of the systems (acetone-ethanol, hexane-benzene, hexane-heptane and methanol-water) has the same behavior. fig.6. variation of boiling heat transfer coefficient with heat flux for ethanol nbutanol. fig.7. variation of boiling heat transfer coefficient with heat flux for acetone-nbutanol. figures (8 9) show the nucleate pool boiling heat transfer coefficients for two binary mixtures (ethanol-n-butanol, acetone-n-butanol) as function of the mole fraction of the more volatile component at different heat fluxes. it was found that the nucleate pool boiling heat transfer coefficients for six binary mixtures were always lower than that of the nucleate pool boiling heat transfer coefficients for the pure liquids. this confirmed that the mass transfer resistance to the movement of the more volatile component was responsible for the decrease in heat transfer coefficient for binary mixture and also the significant change in the physical properties of the mixture and the effect of composition on nucleation of bubbles in binary mixture were also responsible for the decrease in heat transfer coefficiet for binary mixture. the rest of the systems (acetone-ethanol, hexane-benzene, hexane-heptane and methanol-water) has the same behavior. an interesting point is that the maximum deterioration was observed at the concentrations where the absolute concentration differences between vapor and liquid phase were also maximum(y*-x). fig.8. variation of boiling heat transfer coefficient with composition for ethanol -nbutanol. the following is an explanation for this heat transfer deterioration. the bubbles leaving the heated surface are enriched in the volatile component (i.e. lower boiling point component). this results in a reduction of this particular component in the boiling boundary layer in the vicinity of the heated surface. the liquid mole fraction of the volatile component in this layer is therefore lower than that in the bulk liquid. consequently, the boiling temperature in the layer becomes higher than that in the bulk liquid. this can be deduced from a vapor. liquid phase equilibrium diagram of typical binary mixture. for nucleate pool boiling, the heat transfer coefficient is a function of the wall superheat, i.e. the difference between the wall temperature and the liquid boiling temperature. for the determination of this heat transfer coefficient for a binary mixture, the measured wall superheat (based on bulk liquid boiling temperature) is used; whilst the wall superheat in the boiling boundary layer is driving the flow of heat in the latter is smaller than that in the former. fig.9. variation of boiling heat transfer coefficient with composition for acetone-nbutanol. 6.3. testing of experimental results with correlations when designing the evaporator of an aqueous system or non-a aqueous system or refrigeration system, one must be able to accurately predict the boiling heat transfer coefficients of these systems used and heat flux predictions of mixtures are of interest in some cases of evaporator design and also in cryogenics, rocketry and power system design. so a suitable correlation for thermal design must be concluded. the experimental results were tested with three correlations. the first of these was proposed by calus and leonidopoulos [5] the second correlation was proposed by thome [15] the third correlation was proposed by fujita et al [17] the mean deviations and standard deviations were determined for their correlations. figures (10–11) for each binary system measured. by comparing the mean deviation and standard deviations for three correlations. it was concluded that thome’s correlation represented the experimental results better than the others, although both correlations were found to be in good agreement with the data. the mean deviation for thome's correlation was (4.968%) for six binary mixtures while it was (7.713%) for fujita's correlation and it was (9.814%) for calus and leonidopoulos correlation. from these we conclude that thome’s correlation is suitable for general thermal design use since it gives good agreements with experimental data and it is directly applicable to multicomponent mixtures, and it requires a minimum of phase equilibrium data, and it is applicable at high reduced pressures. fig.10. comparison of experimental results with three correlations for ethanol-nbutanol at q" = 115.08(kw/m2). fig.11. comparison of experimental results with three correlations for acetone-nbutanol at q" = 115.08(kw/m2) pool boiling experiments were carried out on boiling of pure and binary mixtures in which the nucleate pool boiling heat transfer coefficients were measured for pure and binary mixtures at atmospheric pressure at which heat fluxes varied up to (133.38) kw/m2. the following conclusions can be reached from an analysis of the experimental data. 1. for a given heat flux, the heat transfer coefficients of mixtures are lower than the values obtained by the pure components constituting the mixture. 2. it was noticed from the present study that the heat transfer coefficient is a function of the difference between the equilibrium vapor and liquid concentration, (y*-x) of the light component and the minimum heat transfer coefficient occurs at the maximum of (y*-x) of the light component. 3. the boiling heat transfer coefficients for either the pure liquids or the binary mixtures increased with the rising heat flux at constant pressure. 4. the data of binary mixtures were compared with three correlations. thome’s correlation yielded a smaller mean deviation than that of fujita and calus and leonidopoulos’ correlation. they compared their correlation with several data sets from literature as well as with their own experimental results. the mean deviation between the predicted and experimental values ranged between (3.6) and (14) percent. to see more models you can see reference [18]. nomenclatures a0 parameter defined in equation (1.4) cp specific heat d mass diffusivity d012, d021 diffusion coefficient of component 1(2) present in infinitely low concentration of liquid mixture fd diffusion factor g parameter defined as:g=(x1-x1,s)/(y1,s-x1,s) h heat transfer coefficient k thermal conductivity lm mass diffusion shell thickness lt thermal boundary layer thickness m molecular weight nu nusselt number [hd/k] p pressure pc critical pressure pr prandtl number [cp μ /k] q" heat flux sn scriven number, defined as: t temperature tw wall temperature tsat saturation temperature v1 volatility parameter, defined by equation (1.24) x mole fraction of the more volatile component y* equilibrium vapor mole fraction greek symbols α thermal diffusivity ∆hlg latent heat of vaporization ∆tbp boiling range ∆teff effective superheat ∆tsat wall superheat [tw – tsat] ∆t1, ∆t2 wall superheat for component (1) and (2) in pool boiling μ viscosity ρ density σ surface tension 7. references [1] coulson, j.m., and richardson, j.f: chemical engineering, vol.1, bath press co.ltd., great britain, 5th edition (1993). [2] van wijk, w.r, vos, a.s., and van stralen, s.j.d: heat transfer to boiling binary liquid mixtures, chem.eng.sci, vol.5, pp.65-80 (1956). [3] grigorev, l.n.: studies of heat transfer of two component mixtures, teplo i masso perenos, no.2, pp.120-127 (1962). [4] stephan, k., korner, m.: heat transfer in boiling mixtures, proceedings of the 7th, heat transferconf., paper rk14, pp.59-81(1982). [5] calus, w.f., and leonidopoulos: pool boiling of binary liquid mixtures, int.j.heat mass transfer, vol.17, pp.249-246 (1974). [6] thome, j.r.: latent and sensible heat transfer rates in the boiling of binary mixtures, 20th edition. joint asme/aiche national heat transfer conference, milwaukee, wisconsin, also asme, pp.81-ht-28 (1981). [7] stephan, k., and korner, m.: calculation of heat transfer in evaporating binary liquid mixtures, chem.ing.tech.vol.41, pp.409-417 (1969). [8] korner, m.: beitrag zum warmeubergang beider blasenverdampfung binarer gemishe, ph.d.thesis, technical university of aachen (1967). [9] thome, j.r.: prediction of binary mixture boiling heat transfer coefficients using only phase equilibrium data, int.j.heat mass transfer, vol.26, pp.965-974 (1983). [10] stephen, k., and preusser, p.: heat transfer and critical heat flux in pool boiling of binary and ternary mixture, ger.chem.eng.vol.2, pp. 161 – 169 (1979). [11] calus, w.f., and rice, p.: pool boiling binary liquid mixtures, chem.eng.sci.vol.27, pp. 1687 – 1697 (1972). [12] scriven, l.e.: on the dynamics of phase growth, chem.eng.sci.vol.10, pp.1-13 (1959). [13] van stralen, s.: the mechanism of nucleate boiling in pure liquids and binary mixtures, int.j.heat mass transfer, pp.990 – 1046, 1469 – 1498(1967). [14] schlunder, e.u.: heat transfer in nucleate pool boiling of mixtures, proc.7th edition, int.heat transfer conf., vol.4, pp.2073-2079 (1982). [15] thome, j.r.: prediction of binary mixture boiling heat transfer coefficient using only phase equilibrium data, int.j. heat mass transfer, vol.26, pp. 965-974(1983). [16] wenzel, u., balzer, f., jamialahmadi, m., and mullersteinhagen, h.: pool boiling heat transfer coefficients for binary mixture of acetone, isopropanol, and water, heat tran.eng. vol.16, pp. 36 – 43 (1995). [17] fujita, y., bai, q., and tsutsui, m.: heat transfer of binary mixtures in nucleate pool boiling, 2 nd eur.thermi.and 14 thuit nat. heat trans. (1996), internet. [18] sultan,a.j, heat transfer of single and binary systems in pool boiling.m.sc thesis universityoftechnology,2006. ومعالجات الماء المنتج من الحقول النفطية بلاسم احمد عبد عباس جواد سلطان قسم الهندسة الكيميائية / الجامعة التكنولوجية الخلاصة يركز البحث على دراسة تأثير مقاومة انتقال الكتلة على معدل انتقال الحرارة في الغليان الحوضي.معاملات انتقال حرارة للغليان المتنوي للخلائط الثنائية (ايثانولبيوتانول,اسيتون-بيوتانول,اسيتون-ايثانول,هكسان-بنزين,هكسان-هيبتان,ميثانول-ماء) تم قياسها عند مختلف التراكيز للمادة الاكثر تطايرا.الانظمة المختارة غطت مدى واسع من تصرفات المحاليل. يتضمن الجهاز المستخدم في البحث على مسخن كهربائي مغمور في سائل الاختبار ومركب بشكل عمودي. درجة حرارة سطح المسخن الكهربائي تم قياسها بواسطة متحسس حراري مربوط بمؤشر رقمي.معدل الانتقال الحراري الحقيقي تم الحصول عليه من حاصل ضرب قراءة الفولتميتر في الاميتر.وقد استخدم مكثف للبخار الناتج بواسطة الحرارة المتولدة من المسخن الكهربائي واعادةالسائل المتكون الى الاسطوانة الزجاجية ليتم اعادة تبخيره. لقد بينت نتائج الغليان بأن معاملات انتقال الحرارة للغليان المتنوي للمزيج الثنائي تكون دائما اقل من معاملات انتقال الحرارة للسوائل النقية.وهذا يؤكد بأن انتقال الكتلة يقاوم حركة المادة الاكثر تطايرا في المحلول وهذا السلوك يفسر النقصان في معاملات انتقال الحرارة للمزيج الثنائي وان اكبر تدهور في معدلات انتقال الحرارة لوحظ عندما يكون مطلق الفرق بين تركيز البخار والسائل للمادة الاكثر تطايرا اكبر مايمكن. النتائج التجريبية تم اختبارها مع اكثر العلاقات شهرة وهي بالتحديد علاقات (كيلس ولينودوبلس, فوجيتا,توم) وقد وجد ان علاقة ( توم) تعطي اكثر تمثيلا للنتائج المختبرية لانها تعطي اقل معدل انحراف واقل انحراف معياري من العلاقتين السابقتين. � embed pbrush ��� 11 9 7 15 _1301293034.unknown _1301293855.unknown _1301294984.unknown _1303973184.unknown _1301295230.unknown _1301294465.unknown _1301293540.unknown _1301293134.unknown _1199353849.unknown _1301292101.unknown _1301292601.unknown _1199353861.unknown _1199353987.unknown _1197621700.unknown _1197621810.unknown _1197046609.unknown _1197046684.unknown _1173207870 al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 4, no. 2, pp 1926 (2008) two domain flow method for leachate prediction through municipal solid waste layers in al–amari landfill site hayder mohammed abdul–hameed university of baghdad/ college of engineering environmental engineering department (received 7 february 2007; accepted april 2008) abstract existing leachate models over–or underestimates leachate generation by up to three orders of magnitude. practical experiments show that channeled flow in waste leads to rapid discharge of large leachate volumes and heterogeneous moisture distribution. in order to more accurately predict leachate generation, leachate models must be improved. to predict moisture movement through waste, the two–domain preflo, are tested. experimental waste and leachate flow values are compared with model predictions. when calibrated with experimental parameters, the preflo provides estimates of breakthrough time. in the short term, field capacity has to be reduced to 0.12 and effective storage and hydraulic conductivity of the waste must be increased to 0.12 and effective storage and hydraulic conductivity of the wasted must be increased to 0.2 and 2.2 cm/s respectively. in the long term, a new modeling approach must be developed to adequately describe the moisture movement mechanisms. keywords: pollution modeling; ground water hydrology; solid waste landfills; leachate generation; two–domain flow. introduction existing leachate prediction models over–or underestimates leachate generation by up to three orders of magnitude. channeled flow in waste leads to rapid discharge of large leachate volumes and heterogeneous moisture distributions (zeiss and uguccioni, 1997). the objectives of this research are to evaluate two modeling approaches by, first, analyzing the theoretical bases of single domain water balance and two domain flow methods and determining the effects of channeling. then, appropriate flow parameters are experimentally determined and leachate generation is predicted with a water balance and two–domain model using experimentally, calibrated parameters. the result are compared with measured values to evaluate the performance, determine deficiencies, and suggest the most appropriate short and long term modifications to predict leachate generation from municipal solid (msw) layers. percolation preflo routes through the profile in two distinct ways depending on the domain. moisture is conveyed through the matrix according to the richards equation (2) with sink terms for water removal by roots addition of water from channels, and removal or addition of water from boundaries. ∂θt= (k(ψ) (h))–r(h,z,t)+pf(h,z,t)–c(h,z,t) …(1) moisture storage in matrix is implicitly determined from the ψ-θ-k relation ship used as in-out into the model because the matrix stores large amounts of moisture if high θ values correspond to high governing values for ψ. for laminar flow through macropores, poiseulle's law (equation 2) is used as the governing equation. qp =  ρgr 4 /8μ …(2) in preflo, moisture is transferred laterally from the channels to the matrix according to darcy's law (equation 1) by accounting for the head differences (workman and skaggs, 1990): hayder mohammed abdul–hameed al-khwarizmi engineering journal, vol.4, no. 2, pp 19-26 (2008) 20 p j,ipj,ij x )kh)(h(krz2 q   …(3) leachate flow in solid waste layers channeled flow is defined as the constricted flow through a fraction of the waste columns cross-section at higher velocities than are valid for darcian flow (zeiss and major, 1993). thus, while darcian flow is laminar and controlled by viscous forces, channeled flow may be laminar or turbulent and is dominated by the higher flow velocities. darcian flow is only valid at reynolds numbers between 1 and 10 (bouwer, 1978; bear, 1972). if the reynolds number is above 10, as calculated from experimental date (uguccioni, 1995), darcys law is not valid. leachate flow through msw occurs in narrow channels and unlike darcian flow in a homogeneous matrix, results in an irregular moisture front (korfiatis et al., 1984; noble and arnold, 1991; roberson et al., 1991). channeling was significant in pilot scale tests (uguccioni, 1995; zeiss and uguccioni, 1997). in this study, moisture movement is characterized by four parameters including (1) breakthrough time, (2) time to steady state or effective storage, (3) leachate volume, and affects leachate collection and treatment system design. experimental methods the experiments were designed to accomplish three research objectives: (a) to confirm channeling, (b) to characterize key flow parameters in pilot scale cells such as practical field capacity fc p, pore size distribution index, effective storage es, hydraulic conductivity kus, breakthrough time tbt, time to effective storage tes, cumulative discharge v. al–amari landfill located at 20 km northeast of baghdad receive 10000–1200 ton/day of solid waste and its consists of a number of cells (around 21) a pilot model were adopted to simulate the cell in the landfill by using the same solid waste composition. a 2 2 factorial design was used in this study to allow for a range of simulation conditions. the two experimental factors were infiltration rate (equal to the precipitation rate because moisture was not allowed to runoff or evaporate) and low level. the high infiltration level was 18 to 25 mm/hr., corresponding to a 10 to 15yr. – 1hr. (according to baghdad mayority/solid waste department records). storm event, while the low level of 7 to 15 mm/hr. corresponded to a 2 yr. the high density cells were compacted to 600 kg/m 3 , corresponding to well compacted landfills. the low density cells were compacted to approximated was 300 kg/m 3 , corresponding with poorly compacted landfills. the experiment was performed in pilot scale cells with dimensions of 1.8 m length by 1.6 m width by 1.5 m height to minimize wall effects. typical residential waste from baghdad city was used, and average channel diameters were determined through supplementary key flow parameters were measured or calculated as follows: (1) practical field capacity, fcp, was calculated by performing a mass balance of water from initial moisture content and infiltration. (2) pore size distribution index, was derived from the published values for similar wastes (schroeder et al., 1994 zeiss and uguccioni, 1995). (3) effective storage, es, was determined from the water balance when the discharge volume reached the infiltration volume. (4) the apparent bulk hydraulic conductivity, kus, was calculated using breakthrough time , waste layer thickness, and fcp, (5) breakthrough time, tbt, was measured, as the time between first infiltration and the appearance of the first leachate discharge. (6) time to effective storage, tes, was estimated from the time of first infiltration to the time when the discharge equaled the infiltration rate. (7) the cumulative discharge, v, was estimated on a daily basis from the volume of leachate discharged. (8) leachate event, tq, was measured as the time between the beginning of leachate discharge (>5ml/day) until flow decreased to less than 5 ml/day. the prediction of leachate flow variables ttb, v, and preflo default parameters as a basis for comparison. the flow parameter values were then determined. from the experiments and used as model inputs. calibrated model runs with experimental values were compared with test and default results. the comparison of predicted to measured values was used to identify model deficiencies and possible improvements. experimental results key flow results are listed in table 1 and shown graphically in figures 1 through 4. the waste and flow parameters generally confirm the presence of channeled flow on a pilot scale using representative unshredded municipal solid waste:  characteristic particle size averaged 7.3 cm with a standard error of 0.5 cm and was therefore similar to reported raw waste particle size and slope (hasselriis, 1984).  average representative pore diameter was 1.9 cm with a range of 1.6 to 2.2 cm hayder mohammed abdul–hameed al-khwarizmi engineering journal, vol.4, no. 2, pp 19-26 (2008) 21  the mean of the practical field capacity, fcp, was 0.12 with a standard error of 0.006 the average value is therefore similar to previous experimental value of 0.1 to 0.13.  average effective storage, es, was 0.19 with a standard error of 0.02. this value is approximately 1.5 times the average practical field capacity.  the resulting apparent unsaturated hydraulic conductivity, kus is between 7.6. 10-5 cm/s and 1.4. 10-2 cm/s, with a mean of 7.3. 10-3 cm/s, or about the same range as previously reported value of 1.18. 10-5 cm/s to 4.46. 103 cm/s (zeiss and major, 1993). specific values of tbt , tes , v, and tq for each experimental cell are illustrated in figures 1 and 2 .  the average break through time (tbt) of 559 minutes with a standard error of 371 minutes is still very close to previously determined is values. these results show that channeled flow is established in large cells as in the time from the beginning of infiltration events to the first discharge is likely to be short in full scale landfills.  on average, the time to effective storage is 24 days with a standard error of 6.7 days. tes is significantly longer for low infiltration intensity cells at 18 to 54 days (see figures 3 and 4).  the cumulative discharges, v, from the cells represents the total leachate volume produced during the experiments (see figures 1 through 4 and table 1). the values for the high infiltration rate cells range between 234 (cell 4, figure 2) and 339 l (cell 2, figure 1) with an average of 135 l the cumulative discharge of the low infiltration rate cells was lower and resulted in higher moisture by approximately 134 l per cell.  the duration of the flow events, tq, from the beginning to the end of discharge is shorter for high infiltration and longer for low infiltration rates, reflecting the additional moisture storage in the low infiltration cells. the average values for this parameter was 35 days with a standard error of 7.7 days. in summary, the experimental results for key flow parameters are consistent with previously measured values and confirm that channeled flow lowers practical field capacity, fcp, and effective storage, es, and increases apparent hydraulic conductivity kus. the flow experiments show lower breakthrough times tbt, and time to effective storage tes, but higher leachate discharges (v) over shorter duration (tq) than flow through a homogeneous porous matrix. model results–evaluation and discussion this section (1) summarizes the results (see also table 3, figures 1 through 4) and describes the methodology used to calibrate the models, and (2) describes the factors leading the results (model deficiencies). preflo predictions were carried out with default values (see table 2) and resulted in zero leachate generation as shown by the horizontal discharge curves in figures 1 through 4. the parameter values were then substituted with the experimental results as summarized in table 2. in order to calibrate the model to achieve better prediction of moisture storage was set to the measured effective storage (approximately 1.5 times the measured practical field capacity). for preflo, the hydraulic conductivity was set 1. 10 -5 cm/s to force flow through the channels. this value also corresponds to the lowest observed apparent unsaturated hydraulic conductivity (7.6 10 -5 cm/s). the calibrated prediction results are compared with measured results and summarized below (see table 3 and figures 1 through 4). breakthrough time tbt particularly for low intensity simulations (averaging 225 to 234 percent of measured). in some cases, preflo predicted drainage before any was observed (figure 1 cell 2, and figure 2 cell 3 and 4). the model begins to route moisture through the matrix at the start of the simulation using the richards equation. if the initial moisture content and hydraulic conductivity of the profile are great enough, water may saturate the bottom node of the profile and drainage will occur. however, after infiltration begins the model routes flow through both channels and matrix. this can be observed from figures 1 and 2. although small volumes of discharge occur prematurely (cells 2, 3, and 4), the drained volume increases considerably when infiltration begins. in contrast, premature drainage may result from one domain models using the richards equation, although these models would not predict a large increase in drainage volume immediately after infiltration because channels are not considered and moisture is routed through the matrix according to the hydraulic conductivity. hayder mohammed abdul–hameed al-khwarizmi engineering journal, vol.4, no. 2, pp 19-26 (2008) 22 time to effective storage tes generally, time to effective storage is underestimated by preflo (table 3). steady-state leachate discharge is not reached in high infiltration preflo simulation. this is because the drainage rate out of the profile is limited by the channel volume and the saturated hydraulic conductivity of the matrix. at low infiltration rats, however, preflo underestimates tes. in these cases, the high moisture content initially present in the cells combined with the amount infiltrating results in discharge volumes equal to infiltration, soon after moisture loading commenced. cumulative leachate discharge volume v preflo accurately predicts the discharge volume during the initial stages of infiltration, for all high infiltration intensity simulation (figure 1 and 2, cells 1through 4). this shown that explicit modeling of channeling improves leachate volume predictions during infiltration events. duration of the leachate flow event tq with preflo, leachate continues to be discharged long after moisture loading ceases and after the measured event has stopped. as a result, the total amount of leachate and the duration of the leachate event predicted by preflo are greater than the measured values. overestimation of the leachate flow event could also occur in one domain models which share preflo's matrix drainage. conclusions and recommendations the experimental waste and flow parameters confirmed channeled flow in pilot scale cells. the practical field capacity of the eight test cells. fcp, averaged 0.12, while the average effective storage, es, was 0.19. help flow conductivity averaged 7.3 .10 -3 cm/s, consistent with previous channeled flow experiments. the average channel diameter was 1.9 cm. experimental values for breakthrough time, tbt, time to effective storage, tes, cumulative leachate volume, v, and duration of the leachate event, tq, averaged 559 minutes, 24 days, 202 l and 35 days, respectively, for the test cells. and the following recommendation may consider: 1. allow infiltration through both the matrix and channels regardless of infiltration; partitioning of flow between the matrix and the channels would be based on cross sectional area of the waste layer each domain occupies and the maximum hydraulic conductivity of the matrix layer. at precipitation rates less than matrix hydraulic conductivity, channels would only receive direct precipitation. however, at precipitation rates greater than the matrix hydraulic conductivity, channels would receive both direct precipitation and excess from the matrix. 2. specify a separate and distinct practical field capacity for the channel areas and the matrix. the channel practical field capacity than the matrix. moisture would be stored in both the matrix and the channels until the practical field capacity of each area is reached, after which drainage would begin (drainage would first begin from the channels due to the smaller storage capacity and then from the matrix). 3. specify effective storage moisture content, es, for the entire layer. this moisture content is greater than the practical field capacity to account for the redistribution from the channels to the matrix. rate from the waste would occur at the effective storage moisture content (waste would not drain to steady state at moisture contents below effective storage). 4. experimentally determine the hydraulic conductivity of the matrix to ensure that the matrix can discharge leachate quickly to reach effective storage. 5. allow drainage from the waste to cease when the drainage field moisture content capacity of the waste is reached. channeled flow would cease when precipitation stops and the channel volume drains to practical field capacity (fcp is the only available storage in the channels); however, the matrix with the additional storage would continue to drain until a drainage field capacity is reached. as discussed, this field capacity, but less than the effective storage. further experimentation is necessary to the necessary parameter values, such as matrix hydraulic conductivity, cross sectional area of matrix and channels, matrix and channeled practical field capacity, effective storage and drainage field capacity. investigative experiments should be conducted in pilot scale cells (as with the experiments in this study) to obtain parameter values. hayder mohammed abdul–hameed al-khwarizmi engineering journal, vol.4, no. 2, pp 19-26 (2008) 23 table 1 pilot cell waste and flow parameter results. parameter mean standard deviation standard error rosin rammler particle size (cm) 7.3 1.7 0.5 pore diameter (cm) 1.9 1.0 0.2 waste height (cm) 88 7.0 3.0 initial moisture content (-) 0.1 0.02 0.007 particle field capacity (-) 0.12 0.016 0.006 effective storage (-) 0.19 0.06 0.02 apparent unsaturated hydraulic conductivity (cm/s) 7.3×10-3 4.9×10-3 1.7×10-3 breakthrough time (min) 559 1069 371 time to effective storage (days) 24 19 6.7 total leachate discharge volume (l) 202 91.6 32.4 duration of event (days) 35 21.8 7.7 table 2 default and calibrated flow parameters for preflo prediction of leachate generation. flow parameter default value calibrated value rationale layer thickness (cm) cell specified (see table 1) these values were determined by the experimental design of the pilot cells and remained constant initial moisture content (-) cell specified (see table 1) porosity (-) 0.67 0.52 experimental porosity was repeatedly determined to be 0.52 saturated hydraulic conductivity (cm/s) 1e-3 1e-5 this value, corresponding to the lowest apparent unsaturated hydraulic conductivity was used to force infiltration through the waste channels pore size distribution index (-) 0.45 0.65 the experimentally determined value of 0.65 was substituted for the default value pore area (percent) 2.0 2.0 the measured value for solid waste (based on the measured pore diameter of 1.9 cm) was applied hayder mohammed abdul–hameed al-khwarizmi engineering journal, vol.4, no. 2, pp 19-26 (2008) 24 table 3 summary of predicted preflo output parameters expressed as percent of measured. case breakthrough time (percent of measured) time of effective storage (percent of measured) total volume discharged (percent of measured) duration of event (percent of easured) low infiltration intensity low compaction cells average (range) 225 50 400 72 56 87 218 118 – 318 175 147 – 203 low infiltration intensity high compaction cells average (range) 234 67 400 54 31 – 76 303 257 – 330 152 107 – 197 high infiltration intensity low compaction cells average (range) 0 -300 300 na* -- 83 75 – 90 391 382 – 400 high infiltration intensity high compaction cells average (range) -850 -1200 500 na* -- 128 126 – 130 577 571 – 582 all simulation average (range) -98 -1200 400 63 31 87 183 75 330 324 107 582 * steady state was not reached in simulations marked na. fig. 1. high infiltration rate, low density results. fig. 2. high infiltration rate, high density results. hayder mohammed abdul–hameed al-khwarizmi engineering journal, vol.4, no. 2, pp 19-26 (2008) 25 fig. 3. low infiltration rate, low density results. fig. 4. low infiltration rate, high density results. references [1] zeiss, c. and m. uguccioni, 1997. modified flow parameters for leachate generation. water environment research 69(3):276-285. [2] zeiss, c. and m. uguccioni, 1995. mechanisms and patterns of leachate flow in municipal solid waste landfills. journal of environmental systems 23(3):247-270. [3] zeiss, c. and w. major, 1993. moisture flow through municipal solid waste: patterns and characteristics. journal of environ-mental systems 22(3):211-230. [4] uguccioni, m., 1995. moisture movement through municipal solid waste. master of science thesis, department of civil engineering 118:214-224. [5] tchobanoglous, g., h. theisen, and s. vigil, 1993. integrated solid waste. management: engineering principles and management issues. mcgraw-hill, toronto, ontario, canada. [6] bagchi, a., 1989. design, construction and monitoring of sanitary landfill. j. wiley and sons, new york, new york. [7] radix, h., 1993, landfill design and operation elseiver. [8] rao, j., 1998, environmental eng. sharmma pub., india. [9] warren, j., 1997, sanitary landfill design chartery university pub. [10] environmental protection agency web site, www.epa.com. [11] green, h., 1998, leachate treatment and control, mc-grew hill, pub. http://www.epa.com/ hayder mohammed abdul–hameed al-khwarizmi engineering journal, vol.4, no. 2, pp 19-26 (2008) 26 حساب الراشح الناتج مه طبقات النفايات الصلبة في موقع العماري بواسطة طريقة الجريان ضمه المجاليه حيدر محمد عبد الحميد قسى انُٓذست انبٛئٛت – كهٛت انُٓذست – خبيعت بغذاد الخالصة بغذاد، اٌ انُخبئح / فًٛب ٚخص انزاشح انًخٕنذ يٍ انُفبٚبث انصهبت انًخٕنذة فٙ يٕقع انعًبرpreflo٘ٚٓذف انبحث انٗ اسخخذاو يٕدٚم انعًهٛت اظٓزث اٌ اندزٚبٌ انقُٕ٘ نًبدة انزاشح ضًٍ انُفبٚبث انصهبت ٚؤد٘ انٗ حفزٚغ كًٛبث كبٛزة يٍ ْذِ انسٕائم يع ٔخٕد حٕسٚع عشٕائٙ ( preflo)ٔنغزض ٔضع صٕرة اكثز ٔضٕحب ٔدقت نعًهٛت حٕنذ انزاشح حى اسخخذاو انًٕدٚم انزٚبضٙ (انًحخٕٖ انًبئٙ)نًسخٕٚبث انزطٕبت ٔفٙ يسخٕٖ breakthrough timeحٛث حى انخُبؤ ٔاسخُخبج سيٍ االخخزاق (نهًٕدٚم)ٔبًدبنٍٛ ٔيٍ خالنّ حًج يقبرَت انُخبئح انعًهٛت ٔانُظزٚت ٔحصٕل سٚبدة فٙ انًٕصهٛت انٓٛذرٔنٛكٛت ٔكذنك انخشٌ انفعبل بًقذار 0.12انًذٚبث انقصٛزة نٕحع حصٕل َقصبٌ فٙ انسعت انحقهٛت بًقذار 0.12ٔ 2.2cm/secايب فٙ يذٚبث انخشغٛم انطٕٚهت فٛدب االعخًبد عهٗ يٕدٚالث اخزٖ حقٕو بخٕصٛف يٛكبَٛكٛت حزكت انزٔاشح . microsoft word (87-93) hussein jabbar hussein al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 5, no. 3 pp 87 93 (2009) دراسة تأثير ازألة الزنك في سبيكة البراص على خواص الكالل ســعد ميخائيل إيليا سميج زيز هــناء ع حسين جبار حسين ة ي التكنولوج ة لجامعا /دمواقسم هندسة (received 25 september 2007; accepted 13 may 2009) الخالصة ثالثــة يتضمن البحث الحالي دراسة عملية إزالة الزنك عن طريق التآكل وتأثيرها على خواص الكالل حيث تم دراسة إزالة الزنــك مــن ســبيكة البــراص ب ملحي بتراكيز مختلفة وأظهرت الدراسة ان اكبر نسبة أزلة تحدث في الوسط القاعدي والتي أدت إلــى أنواع من األوساط وهي الوسط ألحامضي والقاعدي وال انخفاض قيم الخواص الكالل للسبيكة المذكورة حيث تتناسب خواص الكالل للسبيكة تناسباً عكسياً مع مقدار اإلزالة للزنك . fatiguecorrosion brass ,dezincification, الكلمات المفتاحية : المقدمة . ١ يعتبــر النحــاس مــن مجــاميع الفلــزات المهمــة وذلــك المتالكــه خــواص جيــدة تميــزه عــن الفلــزات األخــرى ومــن هــذه الخــواص توصيله الجيد للحــرارة والكهربــاء , مقاومــة جيــدة للتآكــل ,ســهولة تصنيعه ويصنف النحاس من الفلــزات المقاومــة للتآكــل ولتحســين مجموعــة مــن العناصــر والتــي تكــون مــع خواصــه تضــاف اليــه النحاس سبائك النحاس والتــي تقســم إلــى مجــاميع اهمهــا مجموعــة حيــث تتعــرض ســبائك البــراص ]١[البــراص ومجموعــة البرونــز األصفر لعده أنــواع مــن التآكــل مــن أهمهــا هــو التآكــل االجهــادي والتآكل االختيــاري والتآكــل الموضــعي والنحــت ومــن أهــم أنــواع التي تحدث لـــــــــسبائك الـــــــــبراص األصــفر هــو التآكــل التآكل االختــــــــــــياري او مايـــــــــــــعرف بعملــــــــــــــية إزالـــــــــــة ) .dezincificationالزنك( namboodhiri, chaudhary, prakash)قام البــاحثون ( & agrawal]2) ــك 1983]عــام ـــة الزن ) بدراســة ظاهـــرة ازال ـــواع مــن البــراص ذات التركيــب ـــة ان ,63/37 ,70/30( لثالث 60/40 cu/zn( ) 15.7فــي محلــول n مــن االمونيــا باســتخدام ( ) وبتحليـــل وســط hr٢٨٥طريقة الغمر البسيط (المباشـر) لمـــدة ( potentiostaticالتأكــل (المحلـــول) وقيـــاس االستقطـــاب بــــ polarization ــة للبــراص ، اســتنتجت الدراســة إن األنــواع الثالث ول االمونيــا حيــث إن أكثــر األنــواع تــأكال هــو تعاني تأكل في محل يعــاني تأكــل بطــيء ٣٧/٦٣، وان بــراص ٣٠/٧٠بعــده ٤٠/٦٠ جدا حيث ان التآكل وتحلل الخارصين فــي محلــول االمونيــا يعتمــد على تركيز النحــاس المتآكــل وان التشــوه اللــدن يــؤثر كثيــرا علــى عملية التآكل وبالتالي عملية إزالة الزنك . ] k. r. trethewey & i. pinwll. l] (3حثــان (قــام البا ) بدراسة ميكانيكية إزالة الزنــك لســبيكة البــراص فــي ١٩٨٦عام ( ــر ( ــاء البحــ ــتعمال nacl%3.5مــ ــة ) باســ anodic(تقنيــ potentiostate حيث أوضحت النتائج إن ميكانيكية إزالة الزنــك ( ) ممــا يعنــيparabolic type rateتتبع قانون نوع قطع مكافئ ( إن عمليــة إزالــة الزنــك هــي عمليــة انتشــارية حيــث تمــت العمليــة بحدوث تحلل لكل من النحــاس والخارصــين معــا ثــم يتبعهــا أعــادة ترسيب للنحاس. وتم قياس معدل التآكل بتحليل العناصر للمحلــول ) ودراسة مقدار aasاألكال باستعمال جهاز االمتصاص الذري ( زمن. الفقدان في العناصر ومع مرور ال ) ١٩٨٨] فــي عــام (cole & newman ]4)قدم الباحثــان ( مقارنة وحسابات بالطريقة الكهروكيميائيــة لســطح قضــيب للبحــث إلفــا مــن –فــي ســبائك بــراص sccعن ظــاهرة ازالــة الزنــك و transieat anodicخالل دراسة سلوك االنتقــاالت المصــعدية ( behavior وديوم وبأحــداث ) لهذه السبائك في محلول نترات الص ــدوش (ٍ ــد scratchingخ ــريع. وق ــال الس ــة االنفع ــتخدام آلي ) باس أظهرت النتائج ان آلية االنفصال السريع غيــر مناســبة فــي الوســط المستخدم ألن طبقة السطح للبراص تتعــرض إلــى فشــل ميكــانيكي كبير عندما تتعرض إلى االنفعــال، إن نتــائج الخــدوش تتــداخل مــع نتيجة نمو التشقق عبر الحبيبات. آلية التصدع للطبقة ــاب [ ــي ذي ــد عل ــام الباحــث محم ) بدراســة 2001] عــام (5ق ــات لمحطــة توليــد الطاقــة خصــائص الفشــل فــي أنابيــب المكثف ــد جنــوب بغــداد) والمصــنعة مــن ســبائك الكهربائيــة (محطــة تولي نحاسية وتمثل الفشل بخاصيتي التآكل والزحف ، وتم دراسة أنواع تتعــرض لهــا هــذه الســبائك ومنهــا إزالــة الزنــك التآكــل التــي dezincification ـــادي ــل االجه ــققات التآك ــر وتش ـــل التنق وتأك scc والتشققات الموسميـةseason crackers ،وتأكــل الكــالل وأوضحت الدراسة إن أكثر أنواع التآكل التي تتعرض لهــا ســبائك وتأكـــل التنقـــر sccالنحـــاس هـــي تشـــققات التآكـــل االجهـــادي ــأثير كــل مــن hot spot corrosionوتأكــل البقــع الحــارة( ) بت الكبريتات واالمونيا. ) يوضــح ان sccوان الفحص المجهــري لمقطــع الكســر لـــ ( ) تعاني من كثرة الفجــوات والفراغــات بســبب cu/zn 33سبيكة ( المقاومة الضعيفة للتآكل. )٢٠٠٩(٩٣٨٧ ، صفحة3، العدد ٥مجلة الخوارزمي الهندسية المجلد حسين جبار حسين 88 الجزء النظري . ٢ صين إلى النحاس خارصين يضاف الخار –في سبائك النحاس %) لتكــوين ســبائك البــراص ،وهــذه الســبائك 36بنسبة ال تتجاوز( αيمكــن تقســيمها الــى مجمــوعتين هــي مجموعــه الطــور الواحــد( بــراص ) وتتميــز المجموعــه α+βبراص)ومجموعــه الطــورين ( األولى من هذه السبائك بأنها ذات طور واحد هــو المحلــول الجامــد امــد اســتبدالي للنحــاس والخارصــين وهــو محلــول ج) α( الفــا ) ( والذي يمتلك تركيب بلوري مشــابه للتركيــب البلــوري للخارصــين .]٦[وهو المكعب المرتكز الوجه ويمكن تقسيم المجموعه الى عده أنواع أهمهــا بــراص الــدقائق األصفر وبــراص النحــاس األحمــر حيــث تحتــوي ســبائك النحــاس .) %٢٠ – ٥(األحمر نســــبه خارصين تتراوح بــــين إما سبائك النحاس االصفرفتمتلك نسبة خارصين يتــراوح بــين ) % وللحصــول علــى اقصــى جمــع بــين المقاومــة ٣٦ – ٢٠( ) % ٣٠والمطيلية يضاف الخارصــين إلــى النـــــــحاس بــــنسبة ( cartridge)فتكون سبيكة تعرف ببراص االطالقــات األصــفر ( brass يل على البارد .والتي تمتاز بقا بلية التشك تتعرض سبائك البراص بشكل عام إلى عده أنــواع مــن التآكــل ) ٪١٥وخصوصا عند احتوائها علــى نســبه خارصــين اعلــي مــن ( ولذالك فان سبائك البراص االصفرستتعرض لعده أنواع من التآكل ــل ــاري والتآك ــل االختي ــادي والتآك ــل االجه ــو التآك ــا ه ــن أهمه م أنــواع التآكــل التــي تحــدث لســبائك الموضــعي والنحــت ومــن أهــم البراص األصفر هو التآكــل االختيــاري أو مــايعرف بعمليــة إزالــة .]dezincification (]7,6الزنك( من أهم األوساط األكالة لسبائك البراص هو مــاء البحــر وذلــك بسبب امتالكه وفــرة مــن ايؤنــات الكبريتــات والكلوريــدات الســالبة ين في سبائك البراص األصــفر تعتمــد وبما ان عملية نزع الخارص على ايونات الكبريتات والكلوريدات بالتالي سيؤدي ماء البحر الى ــيد ــوين اوكسـ ــق تكـ ــك عـــن طريـ ــفر وذلـ ــل البـــراص األصـ تأكـ ــاد عمليـــة نـــزع الخارصـــين,cuoالنحاســـوز( ــالي ازديـ ) وبالتـ اما التآكــل االجهــادي فانــه يحــدث لســبائك البــراص األصــفر فــي تكون مشبعة بغاز االمونيــا ويحــدث التآكــل التنقــري األوساط التي لسبائك البراص االصفربفعل العوامل الميتالورجيــا ومنهــا اإلنهــاء . ] 8[السطحي العوامل الموثرة على الكالل في سبائك البراص األصفر . ٣ تتعرض األجزاء الهندسية إثناء التطبيق إلى أحمــال ديناميكيــة تســبب فشــل األجــزاء الهندســية بشــكل دوري وبظــروف محيطيــة وتتأثر عملية فشل األجزاء الهندسية بفعل قوى الكالل بعدة عوامل أهما حجم الحبيبة واتجــاه اســتطالتها , واإلنهــاء الســطحي ودرجــة الحرارة والظروف البيئيــة وتركيــز االجهــادات وبــذلك فــأن كــالل سبائك البــراص األصــفر المتعرضــة ألوســاط اكالــة والتــي حــدثت ــاء الســطحي عل ــل اإلنه ــأثراُ بعام ــر ت ــون أكث ــل تك ــة تأك ــا عملي يه والظروف البيئة وتركيز االجهــادات حيــث ســتؤدي عمليــة التآكــل إلى تلف السطح وبالتالي حــدوث التآكــل النقــري وكــذلك الظــروف البيئية المحيطة لهــا تــأثير علــى عمليــة الكــالل مــن تركيــز الوســط . ]10,9[األكال ونوعية ــة ــي مــن أهــم األدل ــة الكــالل هــو منحن ــى فحوصــات عملي عل ) حيــث يتميــز منحنــي s-n curveعــدد الــدورات (–(اإلجهــاد )s-n للمعادن الغير حديديــة بعــدم ظهــور حــد الكــالل وتســتمرا( لعالقة عكسية بين اإلجهاد وعدد الدورات . الجزء العملي . ٤ تم دراسة ظاهرة إزالة الزنك لسبائك البراص كمرحلة أولى ثم إزالة الزنك ) على خواص الكالل ( تمت دراسة تاثيرعملية التآكل .تم استخدام عينات من سبيكة براص الفا األصــفر والمعــروف بـــ ) l=100.5mm,d=8mmبــراص الطلقــات األصــفر باإلبعــاد ( ) حيــث astmحسب تصنيف ( )c26000والتي تحمل الرقم ( اري وبقطــر تــم شــراء قضــبان مــن هــذه الســبيكة مــن الســوق التجــ )12mmالتحليل الكيميائي لمادة القضــبان لغــرض ) وتمت عملية ) يوضـــح نتـــائج١معرفـــة التركيـــب الكيميـــائي ، والجـــدول ( التحليل الكيميائي. -١ –جدول ال يوضح نتائج التحليل الكيميائي للبراص األصفر. العنصر %wt cu s sb ni as mn si fe zn العينة ٠٠٠٫٠٥ 0.00250.008٢0.00440.00500.00800.0043 ٧٠.000 القياسية ٣٠.000 نتائج ٠٠٫٠٠٦ rem. 0.00700.00840.00400.0050٠٫٠٠٨٨٠٫٠٠٣٦ الفحص 30.450 تم اعتماد طريقة الفقــدان بالكتلــة باســتعمال ميــزان الكترونــي ) ذي دقــة قيــاس sartoring analyticحساس نوع ( )+0.0001gmلى حصــول عمـــلية التآكــل للعـــينات )لالستدالل ع وتمت عملية فحص اإلزالة بعد غــمر العينات في األوساط األكالة وكاالتي: )وبتركيــز مــوالري naclاســتخدام ملــح كلوريــد الصــوديوم ( ١ )mيـــوم. بعـــدها يـــتم ٢١) وبمـــدة غمـــر(٢٫٥٬٢٬١٫٥٬١ ( استخراج العينة وغسلها وتجفيفها . )oh4nh( لصـــوديوماســـتخدمت قاعـــدة هيدروكســـيد ا ٢ ) يــوم ٢١)وبمدة غمــر( m٢٫٥٬٢٬١٫٥٬١ وبتركيزموالري( بعدها يتم استخراج العينة وغسلها وتجفيفها . ) وبتركيــز مــوالري ٣so2hاســتخدام حــامض الكبريتيــك ( ٣ )mيــوم , بعــدها يــتم ٢١) بمــدة غمــر ( ٢٫٥٬٢٬٢٬١٫٥٬١ ( استخراج العينات وغسلها وتجفيفها. ت لكل عملية غمر لغرض إجراء فحص استخدمت أربعة عينا ٤ الكالل عليها وذلك للحصول على قراءة جيدة ودقيقــة إضــافة )٢٠٠٩(٩٣٨٧ ، صفحة3، العدد ٥مجلة الخوارزمي الهندسية المجلد حسين جبار حسين 89 إلى عينة السبيكة التــي بــدون معاملــة كيميائيــة العتمادهــا فــي عملية فحص الكالل للسبيكة بدون حصول عملية التآكل . ــات ــك للعملي ــة الزن ــة إزال ــول عملي ــن حص ــد م ــرض التأك لغ اليــل األكالــة تــم إجــراء فحــص المحلــول الــذي المغمــورة فــي المح غمرت فيه العينات ولألوساط األكالــة الــثالث وتــم حســاب تركيــز الزنك فــي كــل وســط تــأكلي . وتــم إجــراء هــذا الفحــص باســتعمال atomic absorption emissian)جهاز االمتصاص الذري aa-670 spectrophotometer) . لفحص الكالل المستخدمة في البحث cnc ةماكنيوضح -١-الشكل يوضح جهاز فحص الكالل المستخدم في البحث -٢-الشكل ل فــي شــركة نصــر تم تشغيل العينات المحضرة لفحــص الكــال ــائن ( ــى مك ــة وعل ــناعات الميكانيكي ــة للص ــب cncالعام ) وحس وقبــل أجــراء ,)1(المواصفات القياسية للعينة والموضحة بالشكل فحص الكــالل أجريــت عمليــة تنعــيم وصــقل لســطح العينــة وعلــى مرحلتين حيث تضمنت المرحلــة األولــى اســتخدام ورق تنعــيم مــن ــد الســيلكون وبدرجــة ( ــا 1200,1000,800,500,320كاربي ) أم ــا اســـتخدام معلـــق المـــاس ( ــد تـــم فيهـ -dpالمرحلـــة الثانيـــة فقـ suspension د تــم إجــراء فحــص ) مــع القمــاش الخــاص بــه. لقــ الكالل في قسم هندسة المواد في الجامعة التكنولوجية والذي يعمــل ــي الشــكل ( ــدوار والموضــح ف ــاء ال ــة االنحن ــتم ٢بطريق ــث ي )،حي إلى اإلجهاد عــن )٣والموضحة في الشكل( تعريض عينة االختبار طريــق عــزم انحنــاء حيــث يبقــى أجهــاد االنحنــاء ثابتــا طيلــة فتــرة ليط الحمل على النهاية الحرة للعينــة والــذي يكــون االنحناء ويتم تس ) وهــذا بــدوره يعــرض xaxisعموديــا علــى محورهــا الســيني ( .]9,8[ل الدورانجهاد ضغط خالإجهاد شد وأسطح العينة إلى ل :ويتم حساب إجهاد االنحناء من خال ib bm  …(1) (2)… ) 32 *( * 3d lp b     l = 100.5 mm , d = 8mm, σb=2p ن :أحيث b إجهاد االنحناء : l ) ذراع الحمل المسلط :mm.( p) الحمل :n.( bm.عزم االنحناء : i.عزم القصور الذاتي : d ) قطر تخصر العينة (اقل قطر في العينة :mm.(( يوضح العينة القياسية المستخدمة في البحث -٣-الشكل اقشةالنتائج والمن . ٥ ريتـــأج يــــالت اتـــــــج الفحوصـنتائ زءــلجيتضمن هذا ا ل االنتقــائي بــالنزع التآكــلبدًء من دراسة لي ـــانب العمــــالج في ــ األوســــاط ) بتـــأثيرdezincification(ملية ـللخارصـــين بعـ الفــا لســبيكة بــراص (الحامضي، القاعدي، والملحــي) ةـالـــــــاألك غمرت الذري للمحلول الذي مع عرض نتائج فحص االمتصاص فيه العينات ونتائج فحص الكالل. )٢٠٠٩(٩٣٨٧ ، صفحة3، العدد ٥مجلة الخوارزمي الهندسية المجلد حسين جبار حسين 90 تأثير نوع الوسط . ٦ أن عملية اإلزالة للخارصــين التــي تعــاني منهــا ســبيكة صفر تتأثر بالوســط البراص (عينات البحث) ذات اللون األ وخصوصا في األوساط المتعادلــة والقاعديــة والتــي تســبب ــي ــاس والخارصــين، الت ــات النح ــى أيون ــبيكة ال ــل الس تحل تفترض حصول المراحل الثالثة (ذوبان الســبيكة، مغــادرة أيونات الزنك، ترسب النحاس الذائب) ، وفي الوقــت الــذي ب فــي المنــاطق تفقد فيه أيونات الزنك قابليتها على الترســي التي تحللت منها يمكن أليونات النحاس الناتجة ان تترســب ثانية في المواقع التي خرجت منها على شكل نحاس أحمــر لذلك تظهر على السطح كناتج عرضــي مــن نــواتج التآكــل بقــع حمــراء اللــون وســط اللــون األصــفر لعينــات الســبيكة ســط فــي ومن خالل ما تقدم سيتم مناقشة تأثير كــل و .]٧[ عملية اإلزالة بالمقارنة مع األوساط األخرى ذات التركيــز نفسه ,أن زيادة نسبة اإلزالة في األوساط الثالثة المســتعملة تتبع التسلسل األتي: 4so2oh > nacl > h4dezincification in nh ) ايون الفلز الثنائي+zn2حيث يمثل ( )nh3المرتبط عن طريق ذرة النتروجين. ) الليكاند ــول ــي المحل ــدث ف ــك يح ــة الزن ــدل إلزال ــى مع إن اعل ـــ ( ــل ب ــن النحــاس oh4nhالقاعــدي المتمث ــالً م ) ، إن ك والزنك الموجودين في سبيكة البراص يحــدث لهمــا ذوبــان ) حيث يكونان]: 3nhبفعل االمونيا ( zn + 4nh3 → [zn(nh3)4]2+ + 2e ...(٣) cu + 2nh3 → [cu(nh3)2]+ + 1e ...(٤) ) يعــد غيــر مســتقر cu+إال أن أيون معقــد النحاســوز ( ــة ــة الثنائي ــى الحال ــجين إل ــود األوكس ــد بوج ــدأ بالتأكس ويب )2+cu: وفق التفاعل ( 2[cu(nh3)2]+ + ½o2 + h2o + 4nh3 →2[cu (nh3)5] 2++2oh ...(5) إلى سيختزل األخير المعقد أيون وان )+]2)3[cu(nh . على سطح السبيكة ( [cu(nh3)٥]٢+ +1e→[cu(nh3)2] ++3nh3 …(6) لـ العالي التركيز فان الظروف هذه مثل وفي )+]2)3[cu(nh سيؤدي إلى تعجيل التفاعل الحاصل ( ) المعادلة للتف 6في مما اكثر المعادلة ) في الحاصل اعل ضمن 3( الهيدروجيني األس حدود يكون عندما ( عملية ph <9> 11.4المدى( حدوث وبالتالي ، ( أعاله المعقد لتكوين المحلول في وذوبانه للزنك اإلزالة إن ذوبان السبيكة أي النحاس على سطح وإعادة ترسيب النحاس يكون كمرحلة انتقالية خالل عملية اإلزالة. إما بالنسبة لعملية اإلزالة الحاصلة في الوسط الملحي: الملحي المحلول المالحظة في لكلوريد فان معدل اإلزالة مطيافية باستعمال بالفحص والمدعم الصوديوم ) الذري في aasاالمتصاص مالحظ مما اقل يكون ،( من أكثر انه إال االمونيوم، لهيدروكسيد القاعدي الوسط ي حالة حصولها في المحيط الحامضي. معدل اإلزالة ف كما معروف إن المركبات المتكونة في محلول كلوريــد الصــــوديوم كوســــط لإلزالــــة همــــا الملحــــان القاعــــديان ]2.zncl26zn(oh)]2] و.zncl24zn(oh) .[ إن األمالح القاعدية المتكونة مــع بلــورات هيدروكســيد لــى ) معــزى إlayer form( الزنك تتواجد بتركيب طبقي كاربونات الزنك القاعدية التــي تكــون بهيئــة طبقــة هالميــة ــد ــك ض ــل الزن ــة تأك ــي مقاوم ــاً ف ــب دوراً مهم ــة تلع كثيف الظروف الجوية.ان جميع المركبات المتكونــة مــع ايونــات ) تحفز الزنك لمغادرة الســبيكة وتكــوين مثــل zn+2الزنك ( هذه المركبات والتي تعد مستقرة. الكلوريد والنترات والكبريتــات ولو افترض ان ايونات وجزيئه المــاء هــي المتنافســة للوصــول إلــى ســطح االنــود ــة ــد بســبب الحجــم والحركي ــون الكلوري ــة ألي ســتكون الغلب فينتج كلوريد المعدن، بما ان جميــع الكلوريــدات ذائبــة فــي ــدرونيوم ( ــتج أيــون الهي ــد تأينهــا تن ) ممــا o3h+المــاء فعن بــة عنــد الســطح أي زيــادة يزيد مــن كميــة األيونــات الموج الشــحنة الموجبــة علــى الســطح ســتحفز ايونــات اكثــر مــن الكلوريد بمهاجمة هذا الموقع وهــذا يعنــي ان تولــد ايونــات موجبة وارتفاع تركيزه, ايونــات الهيــدرونيوم وقلــة ذوبــان األوكسجين وتوقف حركة المحلول وارتفــاع تركيــزه كلهــا يــون الكلوريــد عوامل تســاعد فــي زيــادة ســرعة مهاجمــة ا للموقع وبالتالي زيادة سرعة التآكل الموضعي. لذا لوحظ من خــالل منافســة االيونــات أعــاله ان معــدل سرعة إزالة الزنك تكون على اقلها في المحــيط الحامضــي والذي تحصل فيه ادنــي عمليــات اإلزالــة وان نواتجــه هــي ) البلوريــة غيــر الذائبــة فــي 4znsoملح كبريتات الزنك ( المتكونــة اء والتي تعد اقل ثباتاً واســتقراراً مــن النــواتجالم في كًل من الوسط القاعدي والملحي وبالتالي يتوقع ترســب بلورات ملح كبريتات الزنــك علــى ســطح الســبيكة، والتــي على إزالة االستقطاب عند الكاثود وإعاقة التفــاعالت تعمل ن كثافــة ترفع من جهد السطح والتقليل م الكاثودية وبالتالي التآكــل وإيقــاف أو تقليــل عمليــة تحلــل الزنــك مــن تيــارات السبيكة. نتائج فحص الكالل . ٧ من البيانات التــي حصــل عليهــا مــن جهــاز فحــص الكــالل تــم ) ســــعة (y-axis),حيــــث يمثــــل محــــورs-nإنشــــاء منحنــــى( 3nh zn 3nh 3 nh 2+ )٢٠٠٩(٩٣٨٧ ، صفحة3، العدد ٥مجلة الخوارزمي الهندسية المجلد حسين جبار حسين 91 ) فيمثــل axis-x) أما محــور(as"stress amplitudeاإلجهاد(" )ولجميــع nf"cycle to failureل("لوغاريتم عدد دورات الفشــ ) ،ويالحــظ مــن الشــكل زيــادة عــدد 4العينات والموضحة بالشكل ( دورات الفشل كلما قلت سعة اإلجهاد المسلط. فقد لوحظ عنــد ســعة اإلجهاد العالية يكون عدد دورات الفشل قليال نتيجة التشوه المرن لشــق اللدن الذي يحدث على سطح المعــدن وهــذا يــؤدي إلــى نمــو ا الذي يؤدي إلى الفشل. بين -٤ الشكل البيانية الفشل اإلجهادالعالقة دورات وعدد المسلط للعينات المعاملة ( الحامضية والقاعدية والملحية ) وعند وجود وسط اكال سوف تتكون نفر تاكلية صغيرة على ت وبالتــالي تعتبــر السطح تعمل هذه النقــر كنقــاط لتركيــز االجهــادا كنقاط لنشؤ شقوق الكــالل وبالتــالي ســوف يــوثر علــى حــد الكــالل الذي بدوره يخفض من مقاومة الكالل بصورة كبيرة وكما موضح ).5بالشكل ( المحلول -٥ الشكل وتركيز الفشل دورات عدد بين البيانية العالقة والملح لألوساط والقاعدية الحامضية )وبثبوت ( المسلط اإلجهادية ) mpa 90والبالغ( ٢ – الجدول .العينات التي تم معاملتها قاعديا إليهامضاف األصلية ) للسبيكة s-n( بيانات منحنى average cycles (nf ) cycles to failure(nf) concentration samples n3 n2 n1 13338.33 13339 13337 13339 without treatment pure 22081 22079 22082 22082 1% 2 21116 21118 21114 21116 1.5% 3 11400 11398 11401 11401 2% 4 1323 11325 11321 11323 2.5% 5 ٣ – الجدول .ملحياالعينات التي تم معاملتها إليهامضاف األصلية ) للسبيكة s-nبيانات منحنى( average cycles (nf ) cycles to failure (nf) concentration samples n3 n2 n1 13338.33 13339 13337 13339 without treatment pure 30944 30945 30942 30945 1% 2 20025 20025 20024 20026 1.5% 3 17227 17225 17227 17229 2% 4 11217 11218 11215 11218 2.5% 5 0 20 40 60 80 100 120 140 0 10000 20000 30000 40000 50000 log no. of cycles s tr es s m p a يا ة حامض ات المعامل العين ا ة ملحي ات المعامل العين ديا ة قاع ات المعامل العين 0 5000 10000 15000 20000 25000 30000 35000 40000 45000 0 1 2 3 ول يز المحل ترك نت ورا د دال عد ديا قاع ا ملحي يا حامض )٢٠٠٩(٩٣٨٧ ، صفحة3، العدد ٥مجلة الخوارزمي الهندسية المجلد حسين جبار حسين 92 ٤ – الجدول .حامضياالعينات التي تم معاملتها إليهامضاف األصلية للسبيكة )s-nبيانات منحنى( average cycles (nf ) cycles to failure(nf) concentration samples n3 n2 n1 13338.33 13339 13337 13339 without treatment pure 39676 39676 39675 39677 1% 2 37349 37348 37348 37351 1.5% 3 30643 30645 30641 30643 2% 4 24368 24367 24368 24368 2.5% 5 ٥ –الجدول بعد المعاملة الكيميائية. يوضح حد الكالل للعينات ) mpaاالجهاد( نوع المعاملة ت ١٠٠ العينات المعاملة حامضيا ١ ٩١ العينات المعاملة ملحيا ٢ ٧٨ لمعاملة قاعدياالعينات ا ٣ االستنتاجات . ٨ إن اعلــى معــدل إلزالــة الزنــك يحــدث فــي المحلــول القاعــدي ١ . oh4nhالمتمثل بـ معدل اإلزالة للزنك في الوسط الملحي والحامضي يكــون اقــل ٢ مالحظ في الوسط القاعدي مما ــم ٣ ــي ت ــات الت ــرة للعين انخفــاض مقاومــة الكــالل بصــورة كبي ــا قاعــديا ً بالم ــا معاملته ــم معاملته ــي ت ــات الت ــع العين ــة م قارن حامضيا وملحيا . المصادر . ٩ [1] b.a.ssouli,a. srhiri & h. idrissi,”charcterization and conttrol of selective corrosion of α1,β – brass by a acoustic emission “,ndt and einternational 36,2003 www.elesevier. com / locate/ ndteint. [2] t.k.g namboodhiri ,p.s chaudhary,b.p arkash,&m.k.agrawal, dezincification of brass in concentrated ammonia , corro.sci.,vol. 22,no.11,1982. [3] k.r. trethewey &i .pinwll, "the dezincification of free maching brass in sea water",surface and coating technology, vol.30,no.5,1986. [4] a.t.cole & r.c. newman, k.sieradzki, "a comparison and evaluation of bar surface electrochemical techniques for the investigation of sccin alpha brass ", corro.sci.j.,vol.128no.1,p.p 109(1988). أنابيــبمحمــد علــي ذيــاب ,"دراســة خصــائص الفشــل فــي [5] المكثفات المصنعة من سبائك نحاسية لمحطة كهربــاء جنــوب ــة ــم هندس ــتير قس ــالة ماجس ــداد ", رس ــاجبغ ــادن اإلنت والمع ,٢٠٠١ . [6] http://www.key-tometals.com/article27.htm,zurich9switzerl and “copper and copper alloys “ international and stepcomm erce ag.,2004. د.كاظم عبــاس الموســوي ,د.ساســي ارحومــة الــزنين د.عبــد [7] :e-mailالعزيـــــز الكاســـــح , "التاكـــــل " منشـــــورات elgapub@ dream.vol.ney.mt,2000,elga. [8] w.bolton, "engineering technology " 3rd ed., u.k.,1998. [9] w.d.allister "materials sciennce and engineering an introduction " 6th ed. ,john wiley and sons ,inc.,2003. [10] j.m.gere“mechanics of materials “6th ed.,2004 http://www.engineering.brooks ols.com . hussein jabbar hussein al-khwarizmi engineering journal, vol. 5, no. 3, pp 87 -93 (2009) 93 study effect of dezincification on the fatigue properties of brass alloy hussein jabbar hussein* hanaa a. al-kaisy** saad m. elie*** department of material engineering / university of technology * email: husseinjabbar11@yahoo.com ** email: azeez_49@yahoo.com *** email: saad_elea@yahoo.com abstract this research includes a study of dezincification by corrosion from brass alloys in three types of media, which are acidic solution, basic and slat solution in different percentages. the study show the higher dezincification occurs in basic solution which decrease the fatigue properties where the fatigue properties are inversely proportional with dezincification. (microsoft word \323\341\355\343 \343\315\343\3175159) al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 15, no. 3, sptember, (2019) p.p. 5159 study the effect of residence time parameters on thermal cracking extract phase lubricating oil saleem mohammed obyed department of chemical engineering/ college of engineering / al-nahrain university email: saleem_mo71@yahoo.com (received 12 february 2019; accepted 11 june 2019) https://doi.org/10.22153/kej.2019.06.008 abstract this work studies with produce of light fuel fractions of gasoline, kerosene and gas oil from treatment of residual matter that will be obtained from the solvent extraction process as by product from refined lubricate to improve oil viscosity index in any petroleum refinery. the percentage of this byproduct is approximately 10% according to all feed (crude oil) in the petroleum refinery process. the objective of this research is to study the effect of the residence time parameter on the thermal cracking process of the byproduct feed at a constant temperature, (400 °c). the first step of this treatment is the thermal cracking of this byproduct material by a constructed batch reactor occupied with control device at a selective range of residence time (duration of the reaction) 30, 45, 60 and 75 minutes respectively at a constant temperature (400 °c). the conversion of this byproduct by thermal cracking process reaches 90% for all these residence times. the second step for this study is distillation this cracked extract liquid by atmospheric distillation device, for these various residence times according to the astm-d86 method, to obtain light fuel fractions of gasoline, kerosene and gas oil,in volume percentages 15, 75 and 0 for residence time 30, 5, 60 and 25, for residence time 45, 5, 10, 75, for residence time 60 and (10, 60 and 20) for residence time 75, which separates according to its boiling point. the major physical and chemical properties for feed (extract phase) and cracking extract liquid with its light fuel fractions were experimentally calculated and the results refer to acceptable properties compared with other standard property. keywords: cracking, extract phase, feed liquid, residence time. 1. introduction crude oil is a complex liquid mixture that consist mainly of carbon and hydrogen and small amount of sulfur, oxygen, nitrogen and metals [1]. a petroleum refinery consists of many units such as a chemical separation (catalytic and thermal process) and a physical separation processes that consists of many units, like crude distillation, solvent de asphalting, solvent extraction, solvent de-waxing, and blending. the solvent extraction process is used to treat luboil by solvent, like furfural, n-methyl pyrrolidone (nmp), which can dissolve the aromatic components in one phase (extract) and the rest of the oil in another phase (raffinate). the solvent is removed from both phases [1, 2]. the use of furfural for lubricating oil manufacture has been gaining in comparison with most other solvents. the yield of high viscosity index raffinate varies with the stock being treated [5]. when furfural (or other common solvent) is added to a heavy lubricating oil stock, two liquid phases (or layers) are produced; one (extract) which contains a relatively large amount of furfural with some asphaltic materials dissolved in it, and one (raffinate) which is lean in furfural but rich in high viscosity index oil [1]. the extracts have gravities in arrange of 4 to 13 api and slightly higher boiling ranges than the raffinates and they contain much more sulfur [6]. the extraction operation consists of a series of counter saleem mohammed obyed al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 5159 (2019) 52 current contacts between oil and solvent, vertical packed towers are wider than settling tanks [6]. the general purpose of the solvent process is to separate a general group of materials or hydrocarbons from the oil. for example; propane de asphalting removes dark colored resinous materials, liquid sulfur dioxide extracts unsaturated and aromatic hydrocarbons from kerosene, and furfural treating produces lubricating oil of high viscosity index [1]. speight 2015 make combination between the temperature and residence time to get various conversions, he noticed that there ia a very small residence time when temperature high, similar to high residence time when temperature is low. the cracking temperatures are between 350 °c to 500 °c, the aromatic ring is estimated stable. bianco et al 1993 studied the conversion reaction for the thermal cracking of vacuum residue (vr) at reaction time reaches to 120 minutes at 410 °c to 470 °c, the results which were obtained from this work were used as reference data for the study of residue thermal cracking. kondo et al 2000 studied the thermal cracking for vr by using batch reactor at 400 °c to 440 °c and atmospheric pressure; he noticed the conversion of vacuum residue increased when the temperature of the reaction increased. parkash 2003 viewed that the thermal decomposing for high molecular weight feed depends on many variables such as, temperature cracking, type of feed stock, residence time, and pressure. the main objectives of the present work are to study the physical and chemical properties for the byproduct matter (extract phase), and to study the effect of several residence times (30, 45, 60, and 75) minutes on the thermal cracking of the extract phase by using a batch reactor, and to study the physical and chemical properties for the cracking extract phase liquid and its light fractions. 2. experimental work 2.1. procedure of the work the process of thermal cracking for the extract phase feed was carried out in the designed batch reactor unit which in figures 1 and 2 its volume is about 300 cubic ml. occupied with many auxiliary parts, like an electrical heater, thermocouple, timer, temperature controller, and a hood. 100 ml of the feed (extract phase) will be put in the reactor. the controlled temperature inside the reactor was constant at 400 °c according to another research (was the best to conversion) and various residence time (30, 45, 60, and 75) minutes which is the period for reaction. the distillation process of extract phase feed and cracked extract phase liquid were done in a distillation device which behaves as one tray and the distillation is done at atmospheric pressure. distillation process on the byproduct mater (extract phase feed) and cracked extract phase liquid all these types of residences time will be done by the astmd86 method. and finely, calculate the major properties of the extract phase feed and cracked extract phase liquid also light fuel cuts in order to compare it with commercial types and the possibilities of the use it in various usages. fig. 1. experimental batch reactor unit with distillation unit. [1reactor 2-heater 3-valve 4-thermocouple 5timer 6temperature controller 7-electrical source] fig. 2. flow diagram of experimental batch reactor unit with control system. saleem mohammed obyed al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 5159 (2019) 53 3. results and discussion 3.1. atmospheric distillation method the analysis of the extract phase and different cracked extract phase liquids, for all these ranges of residences time results are shown in table 1. table 1, atmospheric distillation for extract phase feed and various cracked extract feed. volum e % extract phase feed °c the cracked extract liquid feed (°c ) residence time 30 minute residence time 45 minute residence time 60 minute residence time 75 minute 0 70 82 70 76 75 5 122 164 120 150 90 10 160 180 200 220 180 15 170 180 220 230 190 20 178 190 240 270 220 25 182 200 250 290 225 30 190 205 260 300 250 35 200 210 270 310 240 40 205 215 290 310 230 45 210 220 296 300 240 50 215 200 300 300 220 55 220 208 210 300 230 60 225 200 220 260 250 65 230 192 224 210 260 70 240 180 260 210 250 75 245 176 270 212 255 80 250 190 270 220 250 85 260 200 276 230 260 90 280 210 280 225 264 95 tave. 217 195 260 251 233 table 1 represents the atmospheric distillation results for the extract phase feed and cracked extract liquid in deferent residence time of cracking feed in reactor and can be noticed from the above results. the cracking occurs in all selected residence times and the conversion of the extract phase feed reaches above 90% in all selected residence times but the best one is 30 minutes due to their high amount of gasoline product and summarized time for cracking extract phase feed. 3.2 physical and chemical properties for extract phase the physical and chemical properties of extract phase at 400 °c for different residence times (30, 45, 60, and 75) are shown in tables 2, 3, 4, and 5. the properties of the thermal cracking process for extract phase feed at 400 °c and residence time 30 minute are shown in table 2. saleem mohammed obyed al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 5159 (2019) 54 table 2, physical and chemical properties for extract phase feed and its fractions. property extract phase feed the cracking liquid product gasoline product kerosene product gas oil product specific gravity 0.965 0.826 0.79 0.83 0.86 api gravity 15.2 39.8 47.6 38.98 33 mean average boiling point.° c 217 195 155 219 310 density gm. / ��� 0.966 0.821 0.786 0.826 0.855 molecular weight 142 204 130 171 247 refractive index 1.547 1.504 1.479 1.503 1.528 k-factor 10.7 11.6 11.7 11.31 11.24 viscosity (40 °c) c.st 125.1 3 4 2 5.8 viscosity (100 °c) c.st 8 1.3 1.5 0.8 1.9 aniline point °f 50 120 120 130 166 pour point °c -9 -7 ------------- cloud point °c -12 -12 ------------ flash point °c 89 74 45 90 150 fire point °c 93 79 50 94 155 refractivity intercept 1.06 1.093 1.086 1.09 1.1 hydrogen % 11.52 13.61 14.15 13.55 13.1 sulfur % 1.28 1.26 0.28 0.54 0.44 carbon % 87.20 85.87 85.57 85.9 86.46 c/h 7.58 6.3 6.05 6.34 6.6 aromatic % 53 20.27 11.8 21.21 28.26 the extract phase feed is rich with undesirable components such as aromatics, oxygen, nitrogen, and sulfur, so the physical and chemical properties of extract phase feed such as api gravity or specific gravity, density, viscosity and others properties are considerably influenced by high boiling point temperature for constituents like these undesirable components that are concentrated in extract phase feed, so it is important to characterize the heaviest fractions of extract phase feed in order to determine their properties as shown in table 2, 3, 4, and 5. the extract phase feed has high molecular weight so it has a high ability to produce light fractions like, gasoline, kerosene and gas oil. the cracking liquid product with lower average boiling point gives more gasoline yield as at residence time 30 minutes and this is correct for others residence times 45, 60 and 75 minutes as shown in table 1 but in different volume percentages content of gasoline, kerosene and gas oil. on the other hand, the properties of the thermal cracking process for extract phase feed at 400 °c and residence time 45 minutes were shown in table 3. table 3, physical and chemical properties for extract phase feed and its fractions. property extract phase feed the cracking liquid product gasoline product kerosene product gas oil product specific gravity 0.965 0.81 0.77 0.82 0.85 api gravity 15.2 43.19 52.26 35.24 34.97 mean average boiling point.° c 217 229 162 235 305 density gm. / ��� 0.961 0.806 0.766 0.815 0.845 molecular weight 142 181 140 175 245 refractive index 1.547 1.500 1.493 1.515 1.498 k-factor 9.7 11.67 11.71 11.57 11.30 viscosity (40 °c) c.st 125.1 3 7.5 5.8 5.8 viscosity (100 °c) c.st 8 1.3 2.1 1.9 1.9 aniline point °f 50 155 135 150 170 pour point °c -9 -18 ------------ cloud point °c -12 -21 ------------ flash point °c 89 97 50 102 151 fire point °c 93 100 54 106 155 refractivity intercept 1.06 1.097 1.11 1.04 1.075 hydrogen % 11.52 13.85 14.45 13.7 13.25 sulfur % 1.45 1.42 0.15 0.54 0.757 carbon % 87.03 85.73 85.4 85.76 86 c/h 7.58 6.19 5.91 6.26 6.49 aromatic % 53 16.51 7.1 18.86 25.9 saleem mohammed obyed al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 5159 (2019) 55 also the properties of the thermal cracking process for the extract phase feed at 400 °c and residence time 60 minutes were shown in table 4. table 4, physical and chemical properties for extract phase feed and its fractions. property extract phase feed the cracking liquid product gasoline product kerosene product gas oil product specific gravity 0.965 0.82 0.8 0.84 0.87 api gravity 15.2 35.84 41.37 32.95 27.14 mean average boiling point.° c 217 251 170 240 315 density gm. / ��� 0.961 0.814 0.796 0.835 0.864 molecular weight 142 198 141 186 249 refractive index 1.547 1.521 1.505 1.527 1.532 k-factor 9.7 11.69 11.339 11.334 11.447 viscosity (40 °c) c.st 125.1 2 24 9 7.5 viscosity (100 °c) c.st 8 0.6 3.6 2.35 2.1 aniline point °f 50 160 140 158 165 pour point °c -9 -15 ------------ cloud point °c -12 -18 ------------ flash point °c 89 113 56 105 158 fire point °c 93 118 60 110 162 refractivity intercept 1.06 1.114 1.107 1.1095 1.1 hydrogen % 11.52 13.7 14 13.4 12.96 sulfur % 2.15 2.13 0.32 0.84 0.86 carbon % 86.32 85.76 85.68 85.76 86.18 c/h 7.58 6.26 6.12 6.4 6.65 aromatic % 53 18.86 14.16 23.56 30.45 also the properties of the thermal cracking process for extract phase feed at 400 °c and residence time 75 minutes were shown in table 5. table 5, physical and chemical properties for extract phase feed and its fractions. property extract phase feed the cracking liquid product gasoline product kerosene product gas oil product specific gravity 0.965 0.835 0.795 0.83 0.86 api gravity 15.2 34.36 47 38.98 33 mean average boiling point.° c 217 233 165 225 295 density gm. / ��� 0.961 0.830 0.79 0.827 0.855 molecular weight 142 182 133 173 242 refractive index 1.547 1.510 1.483 1.500 1.550 k-factor 9.7 11.35 11.367 11.36 11.449 viscosity (40 °c) c.st 125.1 3.5 38 45 29 viscosity (100 °c) c.st 8 2.7 4.5 1.9 4 aniline point °f 50 152 130 140 100 pour point °c -9 -21 ------------ cloud point °c -12 -24 ------------ flash point °c 89 116 52 95 145 fire point °c 93 120 58 100 150 refractivity intercept 1.06 1.095 1.088 1.0865 1.1225 hydrogen % 11.52 13.47 14.07 13.55 13.1 sulfur % 1.65 1.64 0.39 0.55 0.7 carbon % 86.82 86.06 85.54 85.9 86.2 c/h 7.58 6.39 6.08 6.34 6.58 aromatic % 53 22.77 13.06 21.21 28.23 saleem mohammed obyed al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 5159 (2019) 56 3.2 effect of temperature on volume extract phase in order to study the effect of the temperature on the process with the accumulated volume percentage was studied with increasing of temperature of the process. fig. 3. atmospheric distillation for extract phase feed. figure 3 shows the relationship between the t &v% distillation curve for the extract phase feed. by this distillation curve, can calculate the mean average boiling point for the extract phase feed its equal to 217° c and by this temperature with specific gravity can calculate the molecular weight by empirical equation and other properties which listed in tables 2, 3, 4 and 5. distillation curve for extract phase feed and extract feed cracked in various residence times figures 4, 5, 6 and 7 show the relationship between the temperature and volume percentages distillation curve for the extract phase feed and extract feed cracked in 30, 45, 60 and 75 minutes respectively. the average boiling point temperature for the extract phase feed cracked in (30, 45, 60 and 75) minutes are 195, 229, 251 and 233°c respectively as shown in figures 4, 5, 6 and 7. that means, when this temperature is low, this cracked feed contains high amount of light fractions (gasoline, kerosene and gas oil) than another residence time cracking. the percentage volume of light fractions in various residence times are; 15, 75 and 0 for residence time 30, 5, 60 and 25 for residence time 45, (5, 10, 75) for residence time 60, and (10, 60 and 20) for residence time 75 minutes which separates according to its boiling point as shown in table 1. fig. 4. atmospheric distillation for extract phase feed and extract feed cracked in 30 minutes. saleem mohammed obyed al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 5159 (2019) 57 fig. 5. atmospheric distillation for extract phase feed and extract feed cracked in 45 minutes. fig. 6. atmospheric distillation for extract phase feed and extract feed cracked in 60 minutes. fig. 7. atmospheric distillation for extract phase feed and extract feed cracked in 75 minutes. as shown in table 1, by various residence time 30, 45, 60, and 75 minutes, ability to convert extract feed phase to another light benefit fuel fractions in high conversion, which reaches more than 90% and in different amount of the light fraction products according to their boiling point (ibp, 180 °c) for the gasoline cut, (180, 250 °c) for the kerosene cut, and (250, °350 c) for the gas oil cut, but the more economic one is 30 minutes residence time due to their high amount of gasoline cut production (15, 75 and 0) and summarized of time cracking reaction. saleem mohammed obyed al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 5159 (2019) 58 as shown in figure 3, by the distillation curve for the extract phase feed, the average boiling point can be calculated, and this property will used to calculate other properties for example molecular weight, and then to compare it with commercial product to find the benefit of this work. as shown from tables 2, 3, 4, and 5 the physical and chemical properties for fuel fractions (gasoline, kerosene, and gas oil) which are products from treatment extract feed phase, are acceptable for commercial uses due to their similar property with a commercial one. so it can be said, success will be occur when converting the byproduct matter (extract phase) to another light fuel fraction which can be used as gasoline for automobiles, also it can be used domestically for kerosene, diesel fuel, and for gas oil. 4. conclusions -the ability of thermal cracking for heavy byproduct matter (extract phase) in different residence time and constant temperature 400 °c but the best one was 30 minutes for economic consideration. possibilities obtained light fuel fractions (gasoline, kerosene, and gas oil) from byproduct matter (extract phase) with acceptable properties according to standard properties. possibilities to use these light products for automobile for gasoline and domestic uses for kerosene and diesel fuel for gas oil. 5. references [1] alkilani.a. haitham m. s. taher a. alsahhaf "fundamental of petroleum refining", elsevier b. v. (2010) [2] pillion l. z, interfacial properties of petroleum products, by tayler & francis group, llc, (2005). [3] gary, j. h., and handwerk, g. h. petroleum refining technology and economics. 4th ed. marcel dekker, new york. (2001). [4] alan g. lucas "modern petroleum technology", vol.2 downstream new york (2001). [5] bhaskara rao b.k. "modern petroleum refining processes" 4th ed. indian institute of technology. (2004) [6] speight, j.g. "the chemistry and technology of petroleum,",3rd ed. marcel dekker, new york (1999). [7] levenspiel, o., "chemical reaction engineering" john wiley and sons inc.3ed (1999). [8] speight, j.g. "hand book of petroleum product analysis", usa. (2002) [9] lappas, a. 2nd european summer school on renewable motor fuels warsaw, poland (2007). [10] salvatore j. rand significance of tests for petroleum products, seventh edition, usa, (2003) [11] surinder parkash "petroleum fuels manufacturing hand book" the mc graw – hill companies. (2016). )2019( 5159، صفحة 3، العدد15دجلة الخوارزمي الهندسية المجلم سليم محمد عبيد 59 صدراسة تاثير زمن المكوث على التكسير الحراري لمادة االكسترات المتخلفة من استخال التزييت زيوت سليم محمد عبيد الكيمياوبة/ كلية الهندسة/ جامعة النهرينقسم الهندسة saleem_mo71@yahoo.com :البريد االلكتروني الخالصة من عملية ةهي مادة المستخلص الناتج ة( كازولين ،كيروسين ،كازاويل ) من معالجة مادة فائض ةيتعلق هذا البحث بامكانية انتاج مقاطع وقود خفيف (طور المستخلص) هي بحدود ةنسبة هذه الماده العرضي .النفط الخامة من عملية تكرير لزيادة معامل اللزوجة لزيوت التزيت الناتج االستخالص بالمذيب مذيب وغيرها ، زيت،ةمثل ( مواد عطري ةمن اللقيم (النفط الخام ) الداخل الى وحدات التكرير وتركيبها الكيمياوي يحتوي على العديد من المواد النافع %١٠ في مفاعل دفعي على التكسير ةالغرض من هذا البحث هو بيان تاثير زمن المكوث لهذه المادللزيوت. ةالكثير...) والتي هي سبب انخفاض معامل اللزوج ةهي دراسة اهم الخواص الفيزياوي ةالمرحلة االولى من هذه المعالج وزمن مكوث متعدد. °م ٤٠٠وعند درجة حرارة ثابته ةالعرضي ةالحراري لهذه الماد ) زمن ،(حرارة ةمساعد ةباجزاء سيطرلتكسير الحراري لها في مفاعل دفعي تم تصميمه لهذا الغرض ومجهز كذلك لهذه المادة ومن ثم اجراء ا ةوالكيمياوي ةحيث كان مقدار التحول لهذه الماده العرضي. °م ٤٠٠) دقيقه وعند درجة حراره ثابته ٧٥ ،٦٠ ،٤٥. ٣٠وكان زمن المكوث المختار (فترة التفاعل) ( .لجميع هذه االوقات %٩٠بواسطة التكسير الحراري يزيد على للسائل الناتج من عملية التكسير الحراري وكذلك اجراء عملية التقطير الجوي ةالهام ةوالكيمياوي ةكانت دراسة بعض الخواص الفيزياوي ةالثاني ةالمرحل وحساب كميات على اساس درجة الغليان لها ةكازاويل ) والمفصول ،كيروسين، ( كازولين وذلك للحصول على مقاطع وقود خفيفه astm-d86له تبعا مع ةوالكيمياوي ةوكانت النتائج تشير الى تقارب المواصفات الفيزياوي لهذه المقاطع. ةالهام ةوالكيمياوي ةوقياس بعض الخواص الفيزياوي هذه المقاطع الخفيفه .كوقود للسيارات للكازولين ولالستخدام المنزلي للكيروسين او كوقود ديزل للمركبات وبالتالي امكانية االستخدام وحسب المقطع ةتلك القياسي (microsoft word \323\307\343\355 \346\321\343\322\35589-97) al-khwarizmi engineering journal al-khwarizmi engineering journal,vol. 13, no. 4, p.p. 8997 (2017) augmentation of nanofluids heat transfer in a circular tube with baffled winged twisted swirl generator sami d. salman* ramzi ata abd alsaheb ** *,**department of biochemical engineering/ al-khwarizmi college of engineering/ university of baghdad/ iraq *e-mail: sami.albayati@gmail.com **e-mail: ramzi_eng_1981@yahoo.com (received 14 june 2017; accepted 17 july 2017) https://doi.org/10.22153/kej.2017.07.006 abstract this article introduces a numerical study on heat exchange and corrosion coefficients of zinc–water nanofluid stream in a circular tube fitted with swirl generator utilizing cfd emulation. different forms of swirl generator which have the following properties of plain twisted tape (ptt) and baffle wings twisted tape (btt) embeds with various ratio of twisting (y = 2.93, 3.91 and 4.89), baffle inclination angles (β = 0°, 30° and 30) joined with 1%, 1.5% and 2% volume fraction of zno nanofluid were utilized for simulation. the results demonstrated that the heat and friction coefficients conducted by these two forms of vortex generator raised with reynolds number, twist ratio and baffle inclination angles decreases. likewise, the results showed that the heat transfer rate raised with accretion of zno nanoparticle concentration. furthermore, the maximum rate of heat transfer with significant intension in friction coefficient has been produced by baffle wings tape with ratio of twisting y=2.93 and baffle angle β= -30 with 2% volume fraction of zno nanofluid. keywords: baffled wings twisted tape, nanofluid, heat transfer augmentation, friction factor, uniform heat flux. 1. introduction the thermal performance of heat exchangers can be essentially increased by utilizing heat transfer augmentation techniques. the augmentation techniques can be categorized three major kinds; the active technique, the passive technique and compound technique. the active techniques imposed an extrinsic power like; electrical field, surface vacillation, etc. the passive technique includes additives to gases or liquids, particular face geometries or swirl generator i.e; tape inserts. however, the combined techniques can be created by utilizing at least two or more active and/or passive techniques. different exploratory investigations on these augmentation techniques have been conducted using tape inserts [1-10], while numerical simulation utilizing cfd methods have been reported. pathipakka g & sivashanmugam [11] implemented numerical simulation on heat rate characteristics for al2o3 nanofluid with helical inserts in circular tube using fluent software version 6.3.2. various volume fractions (0.5%, 1.0%, 1.5%) of al2o3 nanoparticles in water conjoined helical twist inserts with various ratio of twisting (y = 2.93, 3.9 and 4.89) were utilized for numerical simulation. the obtained results have been compared with data collected from literature with great assertion. salman et al. [12] have been actualized theoretical study on the heat characteristics and friction factor in circular tube embedded tape with elliptical cut using cfd-fluent software version 6.3.26. two forms of twisted tape have been used; classical and elliptical cut tapes with sami d. salman al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 110 (2017) 90 different ration of twisting (y=2.93 4.89) and various cut depth (w = 0.5 1.5 cm) with water as test liquid were utilized for numerical simulation. the results obtained demonstrate that the heat rate and the friction characteristics conducted by twist tape with elliptic cut have been augmented with reynolds number increasing and decreasing ratio of twisting. likewise, the result demonstrate that the higher heat transfer rate was obtained by tape of elliptical cut with w = 0.5 cm and y=2. 93. salman et al. [13] announced a numerical investigation on heat transfer augmentation in a uniform heat-fluxed tube fitted with v-cut twisted tape in laminar stream of water utilizing fluent software. the simulated results demonstrate that the greatest value of heat transfer improvement was acquired by v-cut tape with cut tape with y=2. 93 w = 0.5 cm model. salman et al. [14] additionally proposed numerical simulation of the heat rate characteristics in a circular tube with twisted tape under steady state heat flux condition using fluent software. plain tapes and baffled tapes with various ratio of twisting (y = 2.93, 3.91, and 4.89) and various angles of inclination (β= 0°, -30°, and 30°) were used for simulation. the results coordinated with the correlations excerpted from literatures for a plain tube within ± 8% and ± 7 % deviation for nusselt and friction factors, respectively. additionally, the results demonstrate that baffled tapes with ratio of twisting y=2.93 and inclination angle β= -30° produced the greatest heat augmentation. the present research reports a numerical study for heat transfer improvement in a tube with baffled winged twist tape (btt) with various ratio of twisting (y = 2.93, 3.91, and 4.89) and various baffle inclination angle (β= 0°, -30°, and 30) conjugated with 1%, 1.5% and 2% volume fraction of zno nanofluid are accounted. the result acquired offered about 10% improvement for nusselt number with noteworthy increments in friction characteristics compared with plain twisted tape. 2. technical specification 2.1. baffled winged tape model baffled winged twist tape (btt) model is demonstrated in figure 1. aluminium tape of 2.45 cm width and 0.08 cm thickness is consistently twisting over different lengths of 7.5, 10, and 12.5 cm to create different ratio of twisting (y = 2.93, 3.91 and 4.89). the ratio of twisting `y' characterized as a fraction of single full twist (360°) length to tape width. stainless steel tube with diameter of 2.54 cm and length of 180 cm was utilized as test sample, water and zno nanoparticles (dp=20 nm) have been chosen as test liquid. the thermo-physical characteristics of substances used for simulation are appeared in table 1 and table 2. table 1, water and zno nanofluids thermo-physical characteristics [15], [16]. liquid density (kg/m3 ) specific heat (j/kg k) thermal conductivity (w/m°c) viscosity (n s/m2) water 997.2 4180 0.6096 0.0009632 zno 5600 495.2 13 – water + 1% zno 1043 3982.35 0.6450 0.001 water + 1.5% zno 1066 3889.83 0.6526 0.0011 water + 2% zno 1089 3801.23 0.6605 0.00106 table 2, material thermophysical characteristics. material density (kg/m3) thermal conductivity (w/m k) specific heat (j/kg k) aluminium 2719 202.4 871 steel 8030 16.27 502.48 sami d. salman al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 110 (2017) 91 fig. 1. (a) baffle winged twist tape with baffle inclination angle (β= 0º) (b) baffle winged twist tape with baffle inclination angle (β= 30º). 2.2. nanofluids thermophysical properties nanofluids thermophysical properties were utilized as a part of this research using equations below [15]: ( ) (1 ) ( ) ( )n f f n pc p c p c pρ φ ρ φ ρ= − + ...(1) (1 )nf f npρ φ ρ φρ= − + ...(2) where (ρcp)f and (ρcp)np are heat capacity of the base liquid and the nanoparticles, respectivly. ρf and ρnp are the densities of the base liquid and the nanoparticles, φ nanoparticle volume fraction the effective thermal conductivity estimated using correlations below [15]: ( 2 ) 2 ( ) ( 2 ) ( ) np f f np s tatic f np f f np k k k k k k k k k k φ φ  + − − =   + + +   ...(3) 45 10 ( , ) 2 b row nian f f np np k t k cp f t r = × ρ φβ φ ρ ...(4) ef f s tatic b row nian k k k= + ...(5) where β = 9.881(100ϕ)− 0.9446 for zno nanoparticle k=boltzmann constant 2 3 2 3 0 ( ,t) (2.8217 10 3.917 10 )( ) ( 3.669 10 3.391123 10 ) t f t − − − −= × + × + − × − ×φ φ φ the effective viscosity estimated using the correlation below [16]: 1.03 0.3 (1 34.87 ( / ) ) f eff dp df − = − × × µ µ φ …(6) 6 fo m df n πρ   =     …(7) where ρfo is the density of the base fluid at temperature to=293 k. m is the molecular mass of base fluid. n is the avogadro number. 3. data structures and numerical analysis 3.1. geometry grid creation the geometry of baffle winged twist tape as exhibited in figure 2 was generated by gambit which exported to ansys-fluent 16 for simulation. this geometry model consists of a plain tube with length of 1800mm and 25.54 mm diameter. plain twist tape with various ratio of twisting was created by twisting consistently piece of width equal to 25.54 mm which utilized by alternative turns edge of 360º for a length of 75, 100, and 125mm to produce the following twist ratios 2.93, 3.91 and 4.89. though, the baffle winged twist tape geometry of with ratio of twisting ( y= 2.93) produced by using cuboids of 25.54 mm width in the broad at a twist angle of 360º and 75 mm length. the desired volume formed for simulation produced by subtract the baffle winged twist tape shape from the plain tube shape and the obtained model exported to the ansys-fluent 16 for meshing and simulation. edge meshing is utilized using specific intervals, while the front surface was meshed by tetrahedral and pave mesh method, then the meshed surface swept through whole volume utilizing t grids form. the boundary conditions of the desired model including; model walls, inlet, outlet, and type of liquid (water) were characterized for cfd simulation. fig. 2. baffle winged twist tape grids with angle of inclination (β= 30º). sami d. salman al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 110 (2017) 92 3.2. mathematical model 3.2.1. hypothesis the suspension nanoparticles in water assumed as single phase fluid under thermal equilibrium.this assumption will precisely define the nanofluid behaviour in engineering cases. the case scrutinized for steady state and laminar flow conditions in three dimension using governing equations with numerical values illustrated in table 3. 3.2.2 equation of mass conservation. .( ) m p s t ρυ ∂ + ∇ = ∂ r ..(8) 3.2.3 equation of momentum conservation ( . ) . ij p g f t υ ρ υ υ ρ τ ∂ + ∇ = −∇ + + ∇ + ∂ ur r ur …(9) 3.2.4 equation of energy conservation. { }( ) .{ ( )} . ( . )eff h eff i e e s k t h t ∂ +∇ + = ∇ ∇ − ∂ + ∑ r r r ρ ρ υ ρ ρ τ υ …(10) table 3, numerical values used for simulation. 4. result and discussion 4.1. model validation and grid independence test the independence of grid was investigated to evaluate mesh sizes influence on the recreated results about; five mesh work volumes were taken into account (401226, 532338, 656404, 727890 and 838278) for re = 2000 which gives different values of nusselt number with percentage deviation up to 0.3%. subsequently, mesh work volume domain of 656404 was performed for plain tube and water as test fluid validates the model versus literature stephan correlations [17]. figures 3 and 4 demonstrate the variety of nusselt number and friction coefficient with reynolds number. evidently, the results sensibly concurred well with these correlations. 4.2. influence of twist ratio varieties of nusselt and friction coefficients versus reynolds number with plain twisted tape existence of are demonstrated in figures 5 and 6. . it’s clearly noted that nusselt and friction coefficients for minimum twist ratios were greater than those obtained from maximum ratio (y). this implied that the minimum twist ratio prompts greater tangential combination between the tube wall and swirl streams. 4.3. influence of tape configuration variety of nusselt and the friction coefficients versus reynolds number with plain twist tape (y = 2.93) and baffle winged twist tape that has similar twist ratio (y=2.93, 3.91 and 4.89) and baffle inclination angles (β= 0º, -30º and 30º) is appeared in figures 7 and 8. it’s discovered that the friction coefficient and nusselt number for a tube with baffle winged twisted tape (y= 2.93) and baffle inclination angle (β= -30º) was greater than the other twisted tapes. the baffle winged twist tape promote an extra liquid turbulences close to tube wall and vortices beyond the baffle winged shape which destructed the thermal boundary layers and generating supercar stream mixing between the liquid and heating surface reynolds number (re) heat flux (w/m2) 240 350 475 600 710 840 950 1075 1200 2100 782.92 1565.85 2348.78 3131.71 3914.63 4697.56 5480.5 6263.42 7046.35 7829.27 ahmed n. al-khazraji al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 8997 (2017) 93 1 6 11 0 500 1000 1500 2000 2500 3000 n u ss el t n u m b er ( n u ) reynolds number (re) simulated nusselt number literature nusselt number fig. 3. numerical nusselt number vs literature correlations for plain tube. fig. 4. numerical friction factor vs literature correlations for plain tube. 0 25 50 75 0 1000 2000 3000 n u ss e lt n u m b e r (n u ) reynolds number (re) ptt (y=4.89) ptt (y=3.91) ptt (y=2.93) fig. 5. the influence of twist ratio on nusselt numbers. 0 0.1 0.2 0.3 0.4 0.5 0 1000 2000 3000 f ri ct io n f a ct o r (f ) reynolds number (re) ptt (y=4.89) ptt (y=3.91) ptt (y=2.93) fig. 6. the influence of twist ratio on friction factor. ahmed n. al-khazraji al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 8997 (2017) 94 0 15 30 45 60 75 0 1000 2000 3000 n u ss e lt n u m b e r (n u ) reynolds number (re) ptt (y=2.93) btt (y=2.93 & β=0°) btt (y= 2.93 & β= -30°) btt (y=2.93 & β= 30°) fig. 7. the influence of tape configuration on nusselt number. 0 0.15 0.3 0.45 0.6 0.75 0 1000 2000 3000 f ri ct io n f a ct o r (f ) reynolds number (re) ptt (y=2.93) btt (y=2.93 & β=0°) btt (y=2.93 & β= -30°) btt (y=2.93 & β= 30°) fig. 8. the influence of tape configuration on fiction factor. 4.4. influence of tape configuration with nanofluds the impact of baffle winged tape with ratio of twisting y=2.93 and baffle inclination angle (β= 30º) with various volume fraction of zno nanofluid on nusselt number and friction coefficient are illustrated in figures 9 and 10. it is plainly noted from figure 8 that the nusselt number well improved with increments of nanoparticles concentration. this implies that the nanoparticles concentration enhanced the random movement of nanoparticles which improves fluid flow thermal dispersion as well and vortices behind the baffle winged configuration. figure 9 demonstrates the friction coefficient variation with the reynolds number for various nanoparticles concentration. it’s unmistakably noticed that the surface shear stress raised with the nanoparticles concentration expansion. 0 10 20 30 40 50 60 70 80 0 500 1000 1500 2000 2500 n u ss e lt n u m b e r (n u ) reynolds number (re) btt (y=2.93 & β= 30° ) btt (y=2.93 & β= 30° with 1% zno) btt (y=2.93 & β= 30° with 1.5% zno) btt (y=2.93 & β= 30° with 2% zno) fig. 9. the influence of tape configuration with nanofluid concentration on nusselt number. 0 0.1 0.2 0.3 0.4 0.5 0 1000 2000 3000 f r ic ti o n f a c to r ( f) reynolds number (re) btt (y=2.93 & β= 30°) btt (y=2.93 & β= 30° with 1% zno) btt (y=2.93 & β= 30° with 1.5% zno) btt (y=2.93 & β= 30° with 2% zno) fig. 10. the influence of tape configuration with nanofluid concentration on friction factor. ahmed n. al-khazraji al-khwarizmi engineering journal, vol. 13, no. 4, p.p. 8997 (2017) 95 5. conclusion numerical simulations for rate of heat transfer in a tube with classical and baffle winged tapes as well 1-2% volume fraction of zno nanofluid was completed utilizing by ansys-fluent version 16. the results obtained were matched with literature correlations for validation with the inconsistency up to ±10% for friction characteristics and ± 8% for the nusselt number. the results demonstrate that the nusselt number expanded with the expansion of nanoparticles concentration, reynolds number and twist ration as well baffle inclination angles diminishes. likewise, the tape with y=2.93 and baffle inclination angles (β= -30) donated more prevailing than those of (β= 0°,30°) for various reynolds number. in addition, the tape with y=2.93 and baffle inclination angles (β= -30) combined with 2% zno nanofluid offers almost 10% improvements in nusselt number values with considerable increments in friction coefficient than those 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[14] s. d. salman, a. a h. kadhum, m. s. takriff, a. b. mohamad, “numerical investigation of heat transfer and friction factor characteristics in a circular tube fitted with v-cut twisted tape inserts”, the scientific world journal, vol. 2013, article id 492762, 8 pages, 2013. [15] s. d. salman, a. a h. kadhum, m. s. takriff, a. b. mohamad, “heat transfer enhancement of laminar flow in a tube using swirl / vortex generator”, australian journal of basic and applied sciences, 8(19) special 2014, pages: 299-304 [16] r.s. vajjha, d.k. das, “experimental determination of thermal conductivity of three nanofluids and development of new correlations”, international journal of heat and mass transfer, vol. 52, issues 21–22, pp. 4675–4682, 2009. [17] m. corcione,”heat transfer features of buoyancy-driven nanofluids inside rectangular enclosures differentially heated at the side walls”, international journal of thermal sciences, vol. 49, issue 9, pp. 1536–1546, 2010. [18] k. stephan, and p. preußer, “wärmeübergang und maximale wärmestromdichte beim behältersieden binärer und ternärer flüssigkeitsgemische”, chemie ingenieur technik, vol. 51, issue 1, pp. 37, 1979. )2017( 89-97، صفحة 4د، العد13ددسية المجلجلة الخوارزمي الهنم سامي داود سلمان 97 بصفيحة ملتوية ذات األجنحة مجهزفي أنبوب دائري تحسين األنتقال الحراري للموائع النانوية لتوليد الدوامات **عبد الصاحب رمزي عطا * مي داود سلمانسا العراق /جامعة بغداد /كلية الهندسة الخوارزمي /قسم الهندسة الكيميائية األحيائية*،** sami.albayati@gmail.com :البريد اإللكتروني* ramzi_eng_1981@yahoo.com**البريد االلكتروني: الخالصة د بمولد دوامة يقدم هذا البحث دراسة عددية عن التبادل الحراري ومعامالت األحتكاك لتدفق المائع النانوي من الزنك والماء في أنبوب دائري مزو : الصفيحة الملتوية الكالسيكية،تيةوقد استخدمت أشكال مختلفة من مولد الدوامات التي لها الخصائص اال باستخدام ديناميك الموائع الحاسوبي. الجسيمات النانوية مع ) β = 0°, 30° , 30°( للجناحميل بزوايا ، و)y = 2.93, 3.91 and 4.89الصفيحة الملتوية ذات األجنحة وبنسبة التواء ( هذين الشكلين من يت لأظهرت النتائج أن معامالت الحرارة واالحتكاك التي أجرقد و .للمحاكاة (%2 ,1.5,%1)كأوكسيد الزنك وبتركيز حجمي يصل الى قد أظهرت النتائج أن معدل انتقال الحرارة الجناح للصفيحة، كما ميل التواء الصفيحة وزواية نسبة ونقصان عدد رينولدز، ات قد أزدادت بزيادة دوامالمولد في معامل االحتكاك تم زيادة ملحوظة عالوة على ذلك، فإن الحد األقصى لمعدل انتقال الحرارة مع وكسيد الزنك.ألالجسيمات النانوية تركيز أزداد بزيادة مع تركيز حجمي ألوكسيد الزنك النانوي (β = 30°) ميل تصل الى زاويةوب (y=2.93)ذات األجنحة وبنسبة التواء الصفيحة الملتوية الحصول عليها . ٢يصل الى % al khawarizmi engineering journal al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 5, no. 3, pp 23 27 (2009) low cost heart rate monitor using led-led sensor ahmed mahrous ragib department of mechatronics engineering/ al-khwarizmi college of engineering/ university of baghdad email: amrk1978@yahoo.com (received 27 january 2009; accepted 1 july 2009) abstract a high sensitivity, low power and low cost sensor has been developed for photoplethysmography (ppg) measurement. the ppg principle was applied to follow the dilatation and contraction of skin blood vessels during the cardiac cycle. a standard light emitting diodes (leds) has been used as a light emitter and detector, and in order to reduce the space, cost and power, the classical analogue-to-digital converters (adcs) replaced by the pulse-based signal conversion techniques. a general purpose microcontroller has been used for the implementation of measurement protocol. the proposed approach leads to better spectral sensitivity, increased resolution, reduction in cost, dimensions and power consumption. the basic sensing configuration presented is capable of detecting the ppg signal from a finger or toe, and it is very simple to extract the heart rate and heart rate variability from such a signal. keywords: photoplethysmography (ppg), heart rate, light emitting diode 1. introduction photoplethysmography is a combination of the greek word, ‗plethysmos‘ meaning increase and ‗graph‘ is the word for write. it is an instrument used mainly to determine and register the variations in blood volume or blood flow in the body. it is based on the determination of optical properties of vascular tissue using a light source and photo detector (pd). the emitted light is reflected, absorbed or scattered by the blood and tissues and the resultant emerging mojdulated light is measured using a suitable pd. there are two different modes of detection: a transmission mode and a reflection mode. transmission mode, where the light source is on one side of the tissue and the detector on the other, is limited to areas such as the finger, earlobe or toe. however, reflection mode, where the light source and pd are placed in parallel, allows measurement of backscattered light virtually on any skin area. the intensity of the light reaching the pd is measured and the variations are amplified, filtered and recorded as a voltage signal—ppg. variations in the intensity of detected light are caused by blood volume changes underneath the probe.[1] the ppg signal has two components: a dc component, which is a relatively constant voltage, but changes in magnitude depending on the nature of the tissue through which the light passes (skin, cartilage, venous blood, etc) and an ac or pulsatile component synchronous with heart rate (hr) and related to arterial blood volume. the ac pulse shapes are indicative of vessel compliance and cardiac performance and the amplitude is usually 1 to 2% of the dc value. a normal ppg probe consists of an led– photodiode configuration, where leds are light emitters and photodiodes (usually p-type, intrinsic, n-type diode (pin)) are pds. in addition to the detector, good quality operational amplifiers and mid to high resolution analogue-todigital converters (adcs) are required. these other components not only increase system complexity and cost, but also size and power dissipation, all-important factors in miniature, battery-powered systems. the photodiode detectors are also not ideal as they are not spectrally selective and indiscriminately detect ahmed mahrous ragib al-khwarizmi engineering journal, vol. 5, no. 3, pp 23 -27 (2009) 24 wide spectrum light ranging from near infrared to uv. hence, we have developed an led–ledbased ppg sensor requiring only a simple microcontroller and a pair of leds. one of the leds is driven in reverse bias mode to function as a light detector. this is a short reverse biasing step (100–200 μs) to the supply voltage (3.3 or 5v) and the only power draw associated with the detector itself. it is possible to make a very accurate measurement of the leds‘ photocurrent (about 10–100 times smaller than the pin‘s) by using a simple built-in timer circuit and the capabilities of the hi-z input state of the microcontroller port. the time it takes for the photocurrent generated on the detector led to discharge its capacitance from logic ‗1‘ to logic ‗0‘ is measured. additionally, the receiving led operates as a band-pass filter; this leads to a response similar to its emission spectral profile, significantly reducing ambient noise. therefore, the proposed system provides a simple, low cost, battery-powered sensing platform with very good sensitivity and signal-to-noise characteristics.[2] fig.1. a schematic of the basic ppg sensor configuration. 2. material and hr measuring approach the sensing technique proposed in this paper is digital and based on the voltage to pulse duration conversion, eliminating the need for relatively expensive, high-resolution adcs and analogue amplifiers. in its hr detector form, it uses a simple circuit shown in figure 1. the two standard leds (usually ir) are connected to the i/o pins of a general-purpose microcontroller. the emitter led is driven directly from output pin p1. the receiver pd is connected to pin p2, which can operate in output or input mode depending on i/o dir. figure 2 illustrates the sensing principle by algorithmic steps ‗trans.‘ and ‗rec‘ (see figure 2(a)). during ‗trans‘ the emitter diode is switched on (see figure 2(b)) and the receiver diode is immediately (within 100–200 μs) charged to +5 v. this charge is sustained by the inherent capacitance of the diode (typically cr = 10–15 pf). pin p2 is then switched into the highimpedance (hi-z) state (approximately 10 15 ), ‗rec‘. fig.2. (a) algorithmic steps, (b) led’s biasing process and, (c) equivalent circuits. this decreases the leakage current il through the pin p2 down to 0.002 pa. this leakage current is insignificant compared with the typical photocurrent of 50 pa through the diode itself, in normal ambient laboratory lighting when the emitting led is off. figure 2(c) shows electrical models of the diode circuit for direct and reverse biasing. under reverse bias conditions, a simple model for pd is a capacitor in parallel with a current source ir ), which models the optically induced photocurrent for incoming light intensity. the process of led discharging, supposing that ir) has a constant value, can be expressed as equation (1) shows that vp2(t) linearly decreases by time t to zero. [3] using a software timing routine (see figure 2(a)), based on a 16 bits microcontroller timer/counter (tcnt), the voltage vp2(t) is continually polled through its digital equivalent, the logic state of the input pin p2 (see figure 1), until the logic ‗0‘ threshold vtr (~2.2 v) is bone led pd finger +5 p1 p2 led pd microcontroller trans: rec: (a) (b) (c) )1...(. )( )( 1 0 2    t r rp t cr i vccdtti cr vccv ahmed mahrous ragib al-khwarizmi engineering journal, vol. 5, no. 3, pp 23 -27 (2009) 25 reached. the decay time (td) is proportional to the amount of light detected; hence, it measures the diode photocurrent ir(). td is calculated as where ntcnt represents the integer number of timer‘s counts, ftclk is the timer‘s clock, np is the pre-scale factor (1/2, 1/8, 1/64, 1/256, 1/1024) and fclk is the main clock frequency. td decreases when the amount of light received increases, and the diode discharges more rapidly, and therefore, when the amount of light received decreases the diode discharges more slowly and td increases. by measuring td with the emitter led on and off, the differential can be ascertained and compensation made for the effects of ambient lighting. the measurement of td depends on ftclk and could be adjusted by the general microcontroller clock depending on the choice of np. in order to verify the response characteristics of the light receiver led, a simple experiment was performed, the results of which can be seen in figure 3. an obstacle in the form of a metal plate is linearly dislocated from the ir–ir reflective sensor configuration, the tracevp2(t)and tds are recorded for different distances (d). figure 3(a) illustrates vp2(t) for three distances; these correspond to three reflected light levels 1,2 and  3 ( 1 <  2 <  3), whilst figure 3(b) gives the dependence td = f (d) as its secondorder polynomial approximation. consequently, it can be seen that the experimental results follow equation (2). additionally, the presented measurement principle could be effectively used as a simple led–led distance meter. [4] in the case of human finger or toe, due to the configuration of the light paths, the photocurrent is proportional to the volume and fluctuations of blood inside the finger or lobe. it is in the range of 10 −12 a (1 pa) in total darkness to about 10 −6 a (1μa) under maximal reflectance. fig.3. (a) discharging processes for different 1, with corresponding decay times tdi and (b) td as a function of d for reflective sensor configuration. 3. results and discussion the proposed ppg sensor has been tested in its hr configuration. the heart signal acquired using ppg sensing probe comprised an ir (910 nm)–ir (910 nm) 5 mm led (near-infrared 710nm1400nm) combination and the signal was collected in reflectance mode from a finger or toe. an 8 bits avr risc attiny90s2313 microcontroller (atmel corporation) running at 8 mhz and 16 mhz was used and a 16 bits timer counter (np = 1), allowing the resolution of 0.125 μs (8 mhz), measured the decay time (td). data were collected via an rs232 link between the microcontroller and the pc. visual basic and interface card were designed for the importing, post-processing and displaying of data. this combination had the ability to implement filtering, fast fourier transform (fft), time–frequency analysis and statistical analysis.  2... 1 1 )( )( clkp tcnt tclk tcnt clktcnttr r d fn n f t tnvvcc i cr t      fig. 3a. fig. 3b. ahmed mahrous ragib al-khwarizmi engineering journal, vol. 5, no. 3, pp 23 -27 (2009) 26 fig.4. (a) the original ppg signal from the sensor, (b) the filtered ppg signal, (c) the fft of the ppg signal with time, (d) the fft of the ppg signal with frequency. figure 4(a) shows the original ppg signal obtained by ir–ir combination with the processor clock set at 8 mhz (fclk = ftclk = 8 mhz). the signals received contain large dc components or offsets, superimposed with ac characteristics (between 0.1 and 1% of the dc level), which reflect the pulsatile component and can be used to calculate spo2 (spo2 is a measurement of the amount of oxygen attached to the haemoglobin cell in the circulatory system. put simpler it is the amount of oxygen being carried by the red blood cell in the blood. spo2 is given in as a percentage, normal is around 96%. the "s" stands for saturation.). the filtered ac component obtained by a third-order low-pass butterworth filter with normalized border frequency ωn = 0.1 is shown in figure 4(b). the fourier spectrum of the ac component is shown in figure 4(c) and the time corresponding to hr. the hr can be calculated by inversing the time for peak component which occur at t=0.016s, which result to hr= (1/0.016)=62.5 beats/min. the fourier spectrum of the ac component is shown in figure 4(d) and the frequencies corresponding to hr is 62.5 beats/min is indicated. 4. conclusion we have demonstrated that led–led-based ppg sensors in conjunction with the ability to measure the light-induced voltage decay time of the detector led are useful while measuring ppg signals. this optical sensing approach uses very low cost optical and electronic components and is simple to construct and the device costs is only 7 usd. the proposed pulse-duration-based signal conversion technique gives good sensitivity as well as excellent signal-to-noise characteristics and low power consumption since it consumes only 3 mwatts. the results was compared with ordinary heart rate monitor, and it shows that the results was with accuracy of +1%. 5. references [1] b. s. kim and s. k. yoo, "motion artifact reduction in photoplethysmography using independent component analysis," ieee trans biomed eng, vol. 53, pp. 566-8, 2006. [2] miyazaki e, itami s and araki t 1998 using a light-emitting diode as a high-speed, wavelength selective photo detector rev. sci. instrum. 69 3751–4 [3] asada, h, shaltis p, reisner a, rhee s, hutchinson rc., ―wearable ppgbiosensors‖, ieee engineering in medicine and biology magazine, vol.22, no.3, pp. 2840, 2003. [4] a.b. hertzman, ―photoelectric plethysmograph of the fingers and toes in man,‖ proc. soc. exp. biol. med., vol. 37, pp. 529, 1937. 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 time(s) fig. 4a. 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 time(s) fig. 4b. frequency (hz) fig. 4d. frequency (khz) fig. 4c. 0 fs/2=4khz fs=8khz 27 -23، صفحة 3، العذد 5مجلة الخىارزمي الهنذسية المجلذ احمذ محروس راغب 2009 27 مراقب عذد دقات القلب واطئ الكلفة باستخذام متحسس الثنائي الباعث للضىء احمذ محروس راغب جايعت بغذاد/ كهٍت انهُذطت انخىارسيً/ قظى هُذطت انًٍكاتزوٍَكض amrk1978@yahoo.com : انبزٌذ اإلنكتزوًَ الخالصة تى تطىٌز يتحظض قهٍم اطتهالكه نهقذرة وعانً انحظاطٍت وقهٍم انتكهفت الطتخذايه فً انجهاس انذي ٌزاقب عذد دقاث انقهب عٍ طزٌق يزاقبت جزٌاٌ انذو اطتخذو انثُائً انباعث نهضىء كًشع نهضىء وككاشف، . طبق نٍتبع ارتخاء واَقباض األوعٍت انذيىٌت خالل انذورة انقهبٍت (بً بً جً)يبذأ انـ . (بً بً جً) ونغزض تقهٍم انحٍش وانتكهفت وانقذرة انًظتههكت فقذ تى اطتبذال يحىل اإلشارة انتًاثهٍت إنى انزقًٍت انتقهٍذي تى اطتبذانه بتقٍُت تحىٌم اإلشارة باالعتًاد عهى أدث انطزٌقت انًقتزحت إنى تحظض اكبز، سٌادة فً انذقت، تقهٍم فً انكهفت، وكذنك األبعاد . يعانج دقٍق يتعذد االطتخذاياث قذ اطتخذو نهتُفٍذ وانقٍاص. انُبضت . يٍ اإلبهاو نهٍذ وانقذو وإٌجاد يعذل دقاث انقهب وتغٍزاته بصىرة طههت جذا (بً بً جً)انتزاكٍب انًقذيت قادرة عهى كشف إشارة انـ . وانقذرة انًظتههكت mailto:amrk1978@yahoo.com������ 120 al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 4, no.3, pp 120-127 (2008) computer-based ecg signal analysis and monitoring system hadeel kassim al-jobouri* nasser n. khamiss al-ani** *medical engineering department/ college of engineering/ al-nahrain university baghdad, iraq, e-mail: hadeel_bme77@yahoo.com **engineering information college baghdad, iraq (received 6 march 2008; accepted 8 july 2008) abstract this paper deals with the design and implementation of an ecg system. the proposed system gives a new concept of ecg signal manipulation, storing, and editing. it consists mainly of hardware circuits and the related software. the hardware includes the circuits of ecg signals capturing, and system interfaces. the software is written using visual basic languages, to perform the task of identification of the ecg signal. the main advantage of the system is to provide a reported ecg recording on a personal computer, so that it can be stored and processed at any time as required. this system was tested for different ecg signals, some of them are abnormal and the other is normal, and the results show that the system has a good quality of diagnosis identification. keywords: ecg, interfacing software design, data acquisition system, biosignals. 1. introduction the human heart is a complex muscular pump. it is an electrically operated physiological pump that circulates the blood through the body and supplies it with oxygen and nourishment [1]. owing to the importance of the heart, a great interest has been given to monitor the heart operation, to detect its abnormalities. williem einthoven devised the first electrocardiograph (ecg) in 1903 and measured the electrical changes that occurred during the beating of the heart [2]. today the ecg has become an indispensable piece of medical equipment, and with their present wide range of applications, ecgs are found in intensive care units, general wards, clinics, physician’s consulting rooms, and medical facilities, both large and small [3]. for the past several years, computer–based analysis has been widely applied to the electrocardiogram, so that the computer would be capable of performing ecg analysis 24 hours a day. the readings are exact and always consistent and repeated readings are constant, and this analysis has proven beneficial to both patient and physician [4]. the greatest progress to date in the use of computers for the clinical analysis of physiological data has occurred in the field of cardiology. there are several reasons for this; first of all, ecg potentials are relatively easy to measure; secondly, the ecg is an extremely useful indicator for both screening and diagnosis, in addition, certain abnormalities of the ecg are quite well defined and can be readily identified. in this paper, present the interface with the personal computer (pc) as a base for ecg signal monitoring and analysis which has been designed and implemented for detecting several types of ecg abnormalities. 1. system hardware fig.1. shows the proposed ecg system, which consists mainly of two parts; the first is the ecg signal extraction that is responsible of ecg signal detection, filtration and amplification, while the second is the microcomputer interfacing system mailto:hadeel_bme77@yahoo.com hadeel kassim al-jobouri al-khwarizmi engineering journal, vol. 4, no. 3, pp 120-127 (2008) 121 that interface the ecg system with the pc for a next processing of the ecg signal. fig. 1. proposal ecg system blocks diagram. 2.1 ecg signal extractions fig.2. shows the main parts of the ecg signal extraction. fig.3. shows the electronic circuits that used to implement such a system. the following is a brief description of each block from a point of implementation view: i. ecg electrodes: an ag–agcl electrode type is used, because of its low differences of the polarizing potential. analog signal fig. 2. the block diagram for a typical ecg system. . fig. 3. proposal ecg systems design. ii. lead selector network: this network is shown in fig.4. which consists of a combination of resistors and two 8:1 analog multiplexers to achieve the selection of a specified lead from the 12 standard leads by using the low order 6 bits of an octal latch chip to the selection–input pins of the two multiplexers. iii. signal amplification: a precision monolithic instrumentation amplifier is used to amplify the ecg signals by a factor of 100, also a programmable gain amplifier (pga) is used, which consists of a non–inverting amplifier, and gain of this amplifier is variable which is controlled by means of software control. iv. signal filtering: a fourth order butterworth lpf with cutoff frequency (100hz) has been designed to remove the base muscle artifact, second–order hpf with cutoff frequency (0.05hz) has been used also to remove the base line drift. a hum filter or notch filter is designed to remove unwanted power line interference of cutoff frequency ( brf =50hz). v. signal digitization: the analog and continuous time signals measured by the electrodes that are modified by the filtration and amplification circuitry must be converted into digital form in order to be understood by a computer, and this consists mainly of the analog–to–digital converter. the fast, low cost, complete 12–bit successive approximation adc converter used for direct interface to a microprocessor bus[5]. fig. 4. lead selector networks. signal amplification signal filtering signal digitization adc to the interfacing unit ecg electrode signal multiplexing instrumentation amplifier lead selector network filter circuits analog input from the patient leads (electrodes) output latch second stage of amplification address decoding circuit ppi 1 8255a buffer ppi 2 8255a buffer a/d converter i s a b u s hadeel kassim al-jobouri al-khwarizmi engineering journal, vol. 4, no. 3, pp 120-127 (2008) 122 2.2 interfacing system in the ecg interfacing system, the interfacing card is designed after the das stage to put the ecg signal on the isa bus to be transmitted to the pc. the currently used pci bus has a 32–bit data bus and a clock frequency more than four times faster than that of the isa bus. however, because many medical i/o applications don't require the performance of pci, manufacturers of medical equipment continued to produce isa– designed cards, which are relatively easy to customize and cost less than pci components. an 8–bit isa card [6] is used for this interfacing design, because it is sufficient to provide the purpose of the hardware design. fig.5. shows a complete block diagram for the interface card design, which consists of the following subunits: i. programmable peripheral interface (ppi): since 12–bit adc converter is used, here minimum of a 12–bit buffer is needed to hold the data temporarily while the adc is converting the next analog sample, also in order to read the digital equivalent values of samples given by the adc to the computer to be processed via an 8–bit isa bus. for these reasons, and to obtain some flexibility in the interfacing unit, two chips of programmable peripheral interface chip are used. ii. address decoder: the address bus lines are decoded by two 3–8 decoders, which act as a full decoding circuit to detect the selected address on the address bus and generates the select signal to activate i/o device at the proper time, in the same time decodes the address bus to generate chip select signals going to the ppi and octal latches. iii. latching stage: an octal d–type latch chip is used to make the process of the lead and gain selection operates under the software control. iv. buffering stage: all the data bus, address bus and control bus are buffered through three octal buffer line drivers (bi–directional buffer). v. system software the development of the software design must be interactive with the hardware design (as described in fig.2.) of the desired system. quick basic & visual basic languages are used in the software development. 2.3 ecg interfacing systems the two programmable peripheral interface chips must be configured before the unit starts its operation. as well as, the operation of the octal latch and the 12–bit adc are controlled through software in order to select the desired lead to be sampled and the start and end of conversion.  the operating ecg interfacing system program: ecg interfacing card program interacts with the patient to accept the ecg lead for checking all control signals of the adc and reads all the 12 channels to ensure the operation of the adc.  configuration of the two ppi's: two ports a and b of the ppi1 are configured in mode 0 as input ports, and port c is configured in mode 0 as output port; while port a of the ppi2 are configured in mode 0 as output port. 2.4 signal conditioning filteration process have been done physically at the analog stage, but the noise problems was not solved completely since it may be caused by electrodes, cream and skin together that form a kind of battery call with polarized voltage. on occasions this polarized voltage may amount to as much as 100mv. when polarized voltage is high, it not only affects body movement and respiration, but also causes the fluctuations of the baseline. thus, an additional signal conditioning step is required before the ecg waveform analysis and detection, and this can be done by using the hanning filter [7], which is a weighted moving– average algorithm, it is useful for smoothing the signal digitally, and has been extensively used in many applications because of its fast run–time speed and ease of implementation. it is frequently useful to apply this filter several times in succession, i.e. to cascade it, to achieve the desired amount of smoothing. also, there are two main sources of additive noise are artifacts and baseline variations resulting respectively from local myographical activities and body motion. an analysis of the frequency content of the ecg signal shows that almost all the energy of the ecg signals is distributed below 40hz and artifacts and baseline variations are predominantly concentrated above 50hz and around the dc components respectively. the artifacts and baseline variations do not convey any medically useful information and they may affect the performance of peak detection algorithms hadeel kassim al-jobouri al-khwarizmi engineering journal, vol. 4, no. 3, pp 120-127 (2008) 123 fig. 5. a complete bloack diagram for the interface card design. l o d 0 a 1 2 2 1 a 2 5 b 3 r eset 3 6 u 5 a 7 4 0 0 12 3 p b 2 d 3 c s v s ppi (8255) d b 7 b 2 7 i o w a 6 d 4 86 1 0 1 3 2 5 p c 3 p b 5 a 1 2 1 2 2 0 ad574a b 4 a 2 3 a 5 s eco n d s tag eo fa m p lificatio n r d d 1 a 2 9 p a 7 r d r eset a n alo g in p u tf ro m d b 8 b 2 3 d 0 a 6 d 5 3 5 3 5 1 1 1 4 p a 7 a 1 3 1 3 1 9 b 8 b 1 d 0 i o r p b 6 p a 5 l o d 2 d b 9 a 1 d 6 68 6 d 4 a 1 3 s electo rn eto w rk 1 7 1 8 2 4 b 1 1 a 3 1 b 5 t o t h el ead i o w a 2 4 p a 2 p a 3 d b 1 0 r 1 1 0 0 2 1 b 2 5 a 0 d 7 9 7 b 1 8 d 3 a 7 d 0 s tag eo fa m p lificatio n 1 8 1 2 3 7 1 6 b 1 5 a 2 6 a 2 p a 3 b 1 6 a 1 p a 4 r e s e t p c 6 d b 1 1 -5 v a 4 a 0 3 6 1 1 u 3 7 4 l s 3 7 3 1 1 13478 1 3 1 4 1 7 1 8 25691 2 1 5 1 6 1 9 o c c1 d 2 d 3 d 4 d 5 d 6 d 7 d 8 d 1 q 2 q 3 q 4 q 5 q 6 q 7 q 8 q b 1 7 p a 6 a 7 d 1 i b 1 41 5 1 3 3 8 1 7 -1 2 a 1 9 b 1 4 p c 2 3 4 u 1 7 4 l s 2 4 5 1 9123456789 1 8 1 7 1 6 1 5 1 4 1 3 1 2 1 1 gd ir a 1 a 2 a 3 a 4 a 5 a 6 a 7 a 8 b 1 b 2 b 3 b 4 b 5 b 6 b 7 b 8 b 3 1 d 2 c s d 1 u 1 7 4 l s 2 4 5 1 9123456789 1 8 1 7 1 6 1 5 1 4 1 3 1 2 1 1 gd ir a 1 a 2 a 3 a 4 a 5 a 6 a 7 a 8 b 1 b 2 b 3 b 4 b 5 b 6 b 7 b 8 d 7 s t a t u s ( e o c ) a 3 a 1 5 p b 0 a 8 d 2 31 4 1 7 3 9 1 9 b 2 2 a 1 7 d 5 3 3 r e f i n h b 2 9 p a 5 p a 1 p a 0 e n ter d b 0 a 1 0 w r r / c ( s o c ) a 2 0 i b 2 r 1 1 0 0 2 1 p b 6 e n ter a 8 d 3 22 5 1 6 4 0 2 02 b 1 3 p b 2 3 2 a 1 2 p a 6 a 0 a 8 p b 5 b 2 b 3 0 b 1 2 p c 1 a 9 d 4 12 4 1 5 1 2 1 a 2 2 7 4 a 1 5 p b 3 3 1 u 1 7 4 l s 2 4 5 1 9123456789 1 8 1 7 1 6 1 5 1 4 1 3 1 2 1 1 gd ir a 1 a 2 a 3 a 4 a 5 a 6 a 7 a 8 b 1 b 2 b 3 b 4 b 5 b 6 b 7 b 8 c s a 2 8 p b 3 d 6 p a 0 d b 1 r e f o u t p c 0 a 9 d 5 4 0 2 3 1 4 2 2 2 a 2 i b 3 2 8 3 a 3 0 p a 4 3 0 b 2 1 r e s e t u 2 7 4 l s 1 3 8 1 5 1 4 1 3 1 2 1 1 1 0 97 1 52364 y 0 y 1 y 2 y 3 y 4 y 5 y 6 y 7 a g 2 b bcg 1 g 2 a h a 1 8 a 0 p b 0 d b 2 b i p r e f a 9 p a 1 ppi (8255) a 1 0 3 9 2 2 2 5 2 3 u 2 7 4 l s 1 3 8 1 5 1 4 1 3 1 2 1 1 1 0 97 1 52364 y 0 y 1 y 2 y 3 y 4 y 5 y 6 y 7 a g 2 b bcg 1 g 2 a a 3 i b 4 2 9 6 p c 6 b 1 0 + 5 v a 1 p c 2 p c 5 p b 7 d ( 0 7 ) r eset d b 3 c e 1 0 v s p a n d 7 l o a 1 1 a 1 0 3 8 2 4 b 2 0 a 3 d 6 i b 5 3 0 3 5 w r a 6 2 9 p b 4 p c 0 isa bus d b 4 a 0 / s c 2 0 v s p a n p a 2 u 6 a 7 4 0 0 12 3 a 1 1 3 7 2 3 a 2 2 a 4 d 7 i b 6 1 8 3 1 4 2 8 a 1 6 b 2 4 d 6 h a 1 3 2 8 d 5 d m s ( 1 2 / 6 ) a n g . g n d b 1 9 p c 3 a 1 f ig u r e 2 .5 a c o m p le te b lo c k d ia g r a m fo r th e in te r fa c e c a r d d e s ig n a ( 0 1 3 ) a 1 1 1 0 2 2 p c 5 a 4 d 1 i b 7 1 9 3 2 1 0 2 8 b 9 p b 1 + 1 2 b 6 2 7 b 2 6 p c 4 g n d a 2 1 p b 1 p c 7 t o t h es eco n d d b 5 1 1 p b 4 a 5 d 2 i b 8 2 0 3 3 9 2 7 b 7 p b 7 a 2 7 a 1 4 a 7 5 p c 7 p c 1 p c 4 + v s d 4 d b 6 b 2 8 i o r a 5 d 3 9 2 1 3 4 1 2 2 6 hadeel kassim al-jobouri al-khwarizmi engineering journal, vol. 4, no. 3, pp 120-127 (2008) 124 (qrs complex detection algorithm and p wave detection algorithm) if they are not eliminated. in order to eliminate the artifacts and baseline variations, a digital band pass filter is applied to the input signal. this filter is composed of two low pass filters with cut-off frequencies fc1 and fc2 respectively, the filtered signal is the difference of the outputs of these two low pass filters. the first low pass filter was designed with a cutoff frequency around fc1=1.25 hz to attenuate baseline variations, the second one was designed with a cutoff frequency around fc2=50 hz to attenuate the artifacts and the harmonics of the power line. fig. 6. shows the structure of the band pass filter. this filter consists of two branches, each containing two moving average filters in cascade. 2.5 ecg waveform analysis and detection ecg pattern recognition must be employed to identify the various features of the ecg (qrs, p and t waves).  qrs complex identification: qrs complex detection has been implemented firstly by using a second order band pass filter. this filter has a sampling frequency of 200hz and the turning point algorithm reduced the sampling rate to 100hz. the second step in qrs complex detection is to find the first and second derivatives of the input signal and process them, to detect the complex and find qrs duration by using the three–point difference algorithm. p and t wave identification: a predetermined interval of the ecg signal prior to qrs complex is scanned for a positive peak to locate the p wave. actually, p wave is often identified on the basis of both the ecg waveform and its first derivative. t wave is identified as a peak within a predetermined interval of the ecg signal following the qrs complex. 4. system test and results the designed system was tested on a number of cardiac patients and the results are detailed in table 1; ecg patient’s reports are shown in figures 7 – 11. from these results, a clear ecg signal without artifact could be interpreted and reported correctly. smoothing of the signal is important for this purpose and it was efficiently done in most records. fig. 7. ecg patient’s report numbers one. fig. 8. ecg patient’s report numbers two. fig. 9. ecg patient’s report numbers three. unfiltered ecg filtered ecg ∑ average fc=1.25 hz average fc=1.25 hz traingular filter average fc=1.25 hz average fc=1.25 hz traingular filter fig. 6. structure of the band pass filter. hadeel kassim al-jobouri al-khwarizmi engineering journal, vol. 4, no. 3, pp 120-127 (2008) 125 fig. 10. ecg patient’s report numbers four. fig. 11. ecg patient’s report numbers five. table 1 ecg patient’s reports details. ecg patient’s report no. 1 2 3 4 5 age 52 66 48 82 63 qrs rate normal fast slow normal fast qrs width normal normal normal abnormal abnormal qrs regularity regular regular very irregular regular very irregular p's:r's ratio p's=r's p's=r's – p's=r's – p–wave peak normal normal – normal – qrs peak in lead v1 s in v1 s in v1 s in v1 s in v1 s in v1 heart rate (beat/min.) 89 102 50 69 106 max. r–r interval 0.676 sec. 0.596 sec. 1.436 sec. 0.88 sec. 0.66 sec. min. r–r interval 0.656 sec. 0.576 sec. 0.832 sec. 0.848 sec. 0.496 sec. qrs interval 0.101 sec. 0.092 sec. 0.091 sec. 0.122 sec. 0.135 sec. diagnosis normal sinus rhythm sinus tachycardia atrial fibrillation complete left bundle branch block atrial fibrillation with complete left bundle branch block 5. conclusions the benefits in this paper lead to the conclusions that the ecg interfacing system has taken the first step towards the next major advance in the relatively slow evolution of cardiology. the work conducted can be built on to eventually provide a system that will be of enormous benefit to the considerable population affected by heart disease and disorders. overall, this system can be used in hospitals, health centers, nursing homes and clinics. the personal computer was used to provide a medical instrument for ecg signals analysis with the following features: • low cost. • high cmrr, high input impedance and high control gain amplifier. • easily operated and automatically functioning, instead of using manual switches. • this system can detect qrs complexes and p–wave, which help in detecting many types of heart disease. 6. refrences [1] william mcmullen, "physiology lessons for use with the biopac student lab", biopac systems, inc., lesson 6: electrocardiography ii, 1995. http://www.biopac.com, [2] john d. enderle, susan m. blanchardend joseph d. bronzino, "introduction to biomedical engineering", academic press, 2000. [3] john r. hampton, "the ecg made easy", harcourt brace and company limited, 1998. [4] bronzino, joseph d., "the biomedical engineering handbook", ieee press, 2000. hadeel kassim al-jobouri al-khwarizmi engineering journal, vol. 4, no. 3, pp 120-127 (2008) 126 [5] travis robinson, marc dowdell, mark mielke & kreshka niehaus, "a successive approximation adc", an ee 552, 2000. [6] rené møller fonseca, "data acquisition system for the 16 bit isa bus", b.sc. in computer systems engineering, university of southern denmark, 2001. [7] greg hodges, chief geophysicist, “the hanning filter”, furgo airborne surveys, 2003. hadeel kassim al-jobouri al-khwarizmi engineering journal, vol. 4, no. 3, pp 120-127 (2008) 127 تحلٍل أشارج التخطٍط الكهرتائً للقلة المعتمذ على الحاسىب ونظام المراقثح **نصر نافع خمٍس العـانً *هـذٌـل قـاسن وادي الجـثـىري جايعح انُهشٌٍ / كهٍح انهُذسح/ قسى انهُذسح انطثٍح* كهٍح ذكُىنىجٍا انًعهىياخ ** الخالصح ًُخطَظ انكهشتائً نهقهة ًُخطَظ . ٌرُاول هزا انثحث ذصًٍى وذُفٍز يُظىيح ان انًُظىيح انًعشوضح ذعطً يفهىو جذٌذ نهرعايم يع أشاسج ان االجضاء انًادٌح ذرضًٍ . وهى ٌرأنف تصىسج سئٍسٍح يٍ دوائش االجضاء انًادٌح وانثشيجٍاخ انًرعهقح. و ذحشٌشها, خضَها, انكهشتائً نهقهة ًُخطَظ انكهشتائً نهقهة نرُفٍز يهًح ,visual basicوانثشيجٍاخ قذ كرثد تأسرخذاو نغح انـ . ويُظىيح أنشتظ انرثادنً, دوائش ذجًٍع أشاساخ ان ًُخطَظ انكهشتائً نهقهة ًُخطَظ انكهشتائً نهقهة عهى انحاسىب . ذُفٍز أشاسج ان ذكًٍ أهًٍح أنًُظىيح االساسٍح فً انقذسج عهى ذسجٍم ذقشٌش نه هزِ انًُظىيح قذ أخرثشخ . حٍث ًٌكٍ خضٌ انًعهىياخ تعذ أجشاء انقٍاساخ و يعانجرها فً أي وقد يرى يا تشصخ انحاجح انى رنك, أنشخصً ًُخطَظ انكهشتائً نهقهة وأظهشخ هزِ انُرائج أٌ , انثعض يُها هً حاالخ غٍش طثٍعٍح وانثعض االخش حاالخ طثٍعٍح, نًخرهف أشاساخ ان . انًُظىيح نها خاصٍح جٍذج فً ذحذٌذ انًشكهح <4d6963726f736f667420576f7264202d20cdd3ede420e6d2edc7cf20e6e3e5e4cf33372d203437> this is an open access article under the cc by license : al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 18, no. 3, september, (2022) p. p. 3747 study of microbial desalination cell performance; power generation and desalination efficiency using pure oxygen in a cathode chamber hussein h. abd-almohi* ziad t. alismaeel** mohanad j. m-ridha*** *,** department of biochemical engineering / al-khwarizmi college of engineering / university of baghdad / iraq *** department of environmental engineering/ college of engineering/ university of baghdad/ iraq *email: hussein.abd1603@kecbu.uobaghdad.edu.iq **email: ziadtarak@kecbu.uobaghdad.edu.iq ***email: muhannadenviro@coeng.uobaghdad.edu.iq )2022 july 26; accepted 2202une j 6received ( 27.00022.02.https://doi.org/10.22153/kej abstract microbial desalination cell (mdc) is capable of desalinating seawater, producing electrical power and treating wastewater. previously, chemical cathodes were used, which were application restrictions due to operational expenses are quite high, low levels of long-term viability and high toxicity. a pure oxygen cathode was using, external resistance 50 and 150 k ω were studied with two concentrations of nacl in the desalination chamber 15-25 g/l which represents the concentration of brackish water and sea water. the highest energy productivity was obtained, which amounted to 44 and 46 mw/m3, and the maximum limit for desalination of saline water was (31% and 26%) for each of 25 g / l and 15 g / l, respectively, when using an external resistance of 150 kω. at 50 kω, 13 and 12 mw/m3 were obtained, and the maximum desalination limit were 20% and 2% when using 25 g / l and 15 g / l, respectively. the concept of the mixing process was introduced in the desalination chamber to improve the performance of the system, where the highest energy productivity was obtained, which amounted 45 and 47 mw/m3, and the percentage of salt removal in the desalination chamber were 40% and 55% when using 15 g/l and 25 g/l and 150 kω, respectively. this study demonstrated a promising approach to using the mixing process in the desalination room in order to increase the desalination and electrical productivity. keywords: microbial desalination cell (mdc), biocathode, oxygen cathode, voltage, external resistance. 1. introduction energy has become an essential and integral part of society's life to maintain economic growth and a good quality of life. the international energy agency (iea) has published that the global need for energy in 2030 will be 50% higher than it is at now [1], [2]. in addition, there has always been an urgent need to discover meaningful and creative solutions to get fresh water in the previous years, until its true implications emerged in the last few years, since fresh water accounted for just around 2% of total surface water in the world, it has resulted in a genuine focus for researchers on developing innovative and effective methods for water purification and treatment with low waste [3]. aside from the energy component and acquiring clean energy from sustainable sources, which the modern world deems a necessary for reducing pollutants and avoiding the use of oil sources. for example, the desalination process using conventional technology (e.g.: reverse osmosis process) requires about 3.7 watt per hours of electrical energy to treat 1 cubic meter of salt water [3]. this led to the development of a number of technologies, including the microbial desalination cell (mdc) system (8, 9), a modified hussein h. abd-almohi al-khwarizmi engineering journal, vol. 18, no. 3, p.p. 3747 (2022) 38 version of the microbial fuel system (mfc) and the bio-electrochemical system (bes) system [2], [4], [5]. even with water that has less than 2000 mg/l of cod, mdc has shown excellent effectiveness in decreasing pollutants in wastewater by transforming it into electrical energy. this system will aid in the processing and generation of electrical energy and wastewater, respectively. over time, it has demonstrated encouraging outcomes in the generation of energy and wastewater treatment [6]. the anode chemical equation is expressed as: active microorganisms + biodegradables organics + anaerobic condition → nco2+ 4ne+4nh+ --(1) [2], [7]. the cathode chemical equation is expressed as: o2 +4ne+ 4nh+→2h2o --(2) [8], [9]. alternative methods for desalination processes were found from the introduction of the concept of the microbial desalination cell in 2009 for water desalination and wastewater treatment, as well as the production of electrical energy [3]. cao et al. (2009) were successful in removing more than 90% of (total dissolved solids) tds using a ferricyanide catholyte with initial tds concentration 35 g/l [10]. mehanna et al. (2010) used platinum (pt) catalysts to replace the ferricyanide cathode with an air cathode. using same amounts of anode solution and saline solution, the air cathode microbial desalination cell eliminated 43–67% of the tds from saline solution [11]. jacobson et al. (2011) built a l-1 upflow microbial desalination cell (umdc) for continuous mode (with 2.75 l) and catalyzed the air cathode using a platinum/carbon (pt/c) solution combination. found that the (tds) removal rate was 11.61 ± 1.69 nacl l/day was when the salt solution's initial conductivity was 56.7 ± 1.4 mscm-1 [12]. chen et al. (2011) developed a stacked mdc (smdc), by inserting pairs of cells between the anode and cathode of the air. it was concluded that the introduction of additional pairs of cells led to an increase in the internal resistance, so the best number of pairs was 1.5 per cell for smdc. microbial desalination cell is considered as one of the promising technologies because it is versatile and produces electrical energy and can be applied on a large scale [13]. however, there is a negative aspect of the system when using chemical cathodes such as (ferricyanide cathodes) as they are toxic and harmful to the environment [14]. for this reason, alternatives have been found, such as using aerobic cathodes, pure oxygen, algae, bacteria, and others. the most often used reaction acceptor is oxygen because of its high reduction potential as well as low saving cost and air being a free and permanent resource [14]. in this study, a pure oxygen cathode was introduced as an electron acceptor to work as a catalyst to improve the desalination process and remove organic matter from the anode chamber. 2. method 2.1 mdc structure three cubic chambers mdc with (10×7×10) cm were made using plexiglass. (6×6) cm (ami7000, membranes international) and (cmi-7001, membranes international) as anion exchange membrane and cation exchange membrane respectively used to separate between the chambers. before usage, the membrane was soaked in a 5% nacl solution for 24 hours and washed with distilled water, which aids in hydration and expansion. graphite plate cut as (8 ×0.5×5) cm shape as anode and cathode electrodes, the working volume of anode chamber is 350ml, desalination chamber is 250 ml and cathode chamber are 350 ml. 2.2 microorganisms and electrolyte all microbial desalination studies used 45 ml of acclimatized anaerobic sludge taken from the first gas power plant in southern baghdad, iraq. a synthetic wastewater solution containing (2.778g/l) of sodium acetate was used in the anode chamber. in the cathode chamber, pure oxygen was supplied at a rate of 1 l/min; both electrodes utilized in the anode and cathode chambers were pure graphite plates with dimensions of (8*0.5*5) cm. 2.3 mdc start-up and operation in earlier investigations, the microbial desalination cell was operated in a biofuel cell mode compared with the mdc cell. all experiments were performed in batch process. the start-up phase consisted of introducing all essential solutions just once during the whole experiment, with no addition or replacement of solutions during the experiment. two concentrations of salts were studied in the desalination chamber at (15 g/l), which represents turbid water, and at (25 g/l), which represents sea salt. the external resistance was hussein h. abd-almohi al-khwarizmi engineering journal, vol. 18, no. 3, p.p. 3747 (2022) 39 changed with two values of 150 kω and 50 kω, and the influence of the mixing process was introduced into the desalination chamber to evaluate the efficiency of the desalination process and to increase electrical energy productivity. the system was set to run at a temperature of 25 ± 3 degrees celsius. 2.4 sem analysis x-ray spectroscopy in conjunction with scanning electron microscopy (sem) (edx) a scanning electron microscope was used to examine the surface shape and topographical details (sem). the generated images are threedimensional and accurately depict the surface contour. the energy dispersive x-ray spectrophotometer is used to examine the precursor elements (eds). sem-eds analysis was performed using tescan, vega iii, czech republic. 3. result 3.1 electricity performance for mdc the system was operated in the first experiment when a concentration of nacl 25 g/l was used in the middle chamber and 50 kω as an external resistance for 12 hours continuously. in the second experiment, the system was operated for 24 hours when using 15 g/l of desalination in the desalination chamber and 50 kω as an external resistance. the rest of the experiments lasted about 48 hours of operation. in the first hours of operation, a rise in the peak level of the microbial desalination cell was observed, and then gradually decreased throughout the rest of the operating period, as shown in figure 1 and 2. the maximum power generated in the first experiment with 150 kω at a salt concentration of 15 g/l reached 44 mw/m3 and at 25 g/l of salt concentration it reached 46 mw/m³, while in the second experiment the maximum power generated reached 13 and 14 mw/m3 for each of 15 and 25 g/l of salts, respectively. the ph values of the system showed a decrease in its value as a result of the transfer of chlorine ions derived from middle chambers to an anode chamber which caused a decrease the ph value from 8.31 to 7.01. the lower power was caused primarily by the lower potential of the cathode with ventilation. as shown in the figure 3, introducing the mixing process in the desalination chamber to positively influence the production of electrical power. an experiment was studied using two concentrations of salts in the desalination chamber (15-25 g/l) with a fixed external resistance of 150 k ω. this change led to an increase in electrical power production by about 45 and 47 mw/m3 for each of 15 and 25 g/l, respectively. fig. 1 show the performance of the mdc with 150 kω of the external resistance and with 25-15 g/l of nacl in desalination chamber with continuous pure o2. hussein h. abd-almohi al-khwarizmi engineering journal, vol. 18, no. 3, p.p. 3747 (2022) 40 fig. 2 show the performance of the mdc with 50 kω of the external resistance and with 25-15 g/l of nacl in desalination chamber with continuous pure o2. fig. 3. show the performance of the power generation in mdc with 150 kω of the external resistance and with 25-15 g/l of nacl in desalination chamber with mixing. 3.2 tds concentration removal the conductivity of saline for concentrations of nacl 15 g/l and 25 g/l when using the mixing process and without using the mixing process is shown in figure 4 and 5. the percentage of desalination depends on a change in the conductivity of the solution, as the decrease in the conductivity in the desalination chamber leads to a decrease in the desalination rate because a small part of the water may move from the middle chamber to the cathode chamber. in the current study, the minimum conductivity reached was 24.5 ms and 16.8 ms when use 150 k ω as external resistance and 25 g/l and 15 g/l of nacl concentration in the middle chamber, respectively, and the desalination was 31% and 26% at 25 g/l and 15 g/l of tds concentration in the middle chamber after 48 h operation, respectively; the minimum conductivity achieved was 29.9 ms and 22.09 ms when using 50 k ω as external resistance and 25 g/l and 15 g/l of nacl concentration in the middle chamber, respectively, the maximum desalination obtained was 20% when 25 g/l of tds concentration in the middle chamber with 24 h of operation time and 2% when 15 g/l tds concentration in the middle chamber with 12 h of operation time. the effect of mixing improves decreasing in the conductivity in the desalination chamber, 16 ms and 24 ms when using 150 k ω and with 25 g/l and 15 g/l of tds concentration in the desalination chamber, respectively, the mixing improves the desalination efficiency and reached 55 % and 40 % when 25 g/l and 15 g/l of tds concentration used in the hussein h. abd-almohi al-khwarizmi engineering journal, vol. 18, no. 3, p.p. 3747 (2022) 41 middle chamber, respectively. as shown in the table 1 the comparison of the desalination rate and efficiency that obtained from this study and previses studies. the presence of na+ and clions in its composition are just a small part of the sea water content. it is nevertheless possible to present ions such hpo4-, po4-2, cl-, k+, and nh4+. when using real wastewater, it may contain a number of complex elements, such as caso4, caco3, mgco3, ca(no3)2, and mgso4, among others. during the desalination process, some of these ions may be transported from saltwater to freshwater, increasing the possibility of water contamination and iem pollution. fig. 4. shown the conductivity of the mdc without using mixing in the desalination chamber. fig. 5. shown the conductivity of the mdc using mixing in the desalination chamber hussein h. abd-almohi al-khwarizmi engineering journal, vol. 18, no. 3, p.p. 3747 (2022) 42 table 1, comparing the performance of microbial desalination cell (mdc). a data calculated according to figures and profiles presented in corresponding articles. b with 0.8 v as additional voltage. c with 150 k ω as external resistance. * tdr (total desalination rate). 3.3 percentage of cod removal in mdc the maximum cod removal value reached in the anode chamber was 35.5% when use 50 kω as external resistance with 25 g/l of tds concentration for 24 h operation time, and 8% when 50 kω as external resistance with 15 g/l of tds concentration for 12 h operation time. 40% and 25% maximum cod removal were achieved when use 150 kω as external resistance with tds concentration (25 g/l and 15 g/l), respectively, for 48 h operation time. the air cathode has become the focus of attention for researchers because of its high potential in oxidation and reduction processes. however, the crossing of oxygen from the cathode chamber to the anode chamber in the mfc system may be the only major drawback of oxygen cathodes [14], [20]. the structure of the microbial desalination cell provides an additional intermediate chamber between the anode chamber and the cathode chamber, which is a buffer zone for the diffusion of oxygen from the cathode chamber to the anode chamber, so it is possible that the anaerobic cathode is promising in the microbial desalination cell. zhang et al. 2014 studied the efficiency cod removal in the anode chamber with air cathode microbial fuel cell (mfc) the maximum cod removal achieved was 78 % with 100 ω as external resistance and 91% with 1000 ω as external resistance this different in the rustles may due to the different in the construction of the cells in the mdc have an addition chamber case increasing in the internal resistance and the time of operation [21]. desalination rate (%) tds concentration (mg/l) tdr (mg/h) * cathode ref. 77 35 2.3 air cathode [15] 100 30 109.4a air cathode with pt [16] 99b 10 1.8a air cathode with pt [17] 80 20 25.2 air cathode with pt [13] 98 35 air cathode with pt [18] 63 20 air cathode with pt [19] 37 20 1.7a air cathode with pt [11] 44 35 air cathode with pt [18] 31 25 0.112c pure o2 cathode this study 26 15 0.02c pure o2 cathode this study 55 25 0.21c pure o2 cathode with mixing in the desalination chamber this study 40 15 0.045c pure o2 cathode with mixing in the desalination chamber this study hussein h. abd-almohi al-khwarizmi engineering journal, vol. 18, no. 3, p.p. 3747 (2022) 43 fig. 6. anode chamber cod elimination effectiveness in mdc. 3.4 biofouling analyses figure 7 (a&b) shows the sem image for the fresh membrane (aem) that used in the mdc and used (aem). figure (7 a) shows the sem image examination of a fresh anion exchange membrane and an unused aem revealed evident differences between the membrane surface and a cracked detected for the new anion exchange membrane. figure (7 b) clearly indicate the fouling layer for the anion exchange membrane employed. the surface of the anion exchange membrane exhibited both biofoulings, which are often generated by bacteria aggregating in the shape of rodes, and inorganic crystalline crusts, which are formed by the deposit of inorganic compounds in synthetic wastewater. figure (7 c) revealed clearly the variation in pore size in the anion exchange membrane (aem) before and after usage. figure (7d) after applying the pore size range of (28.56 µm – 12.17 µm), the pore size range is (26.61 µm – 54.19 µm). this difference is the fundamental reason for lowering the rate of desalination during working hours, since the highest rate is achieved in the early hours. hussein h. abd-almohi al-khwarizmi engineering journal, vol. 18, no. 3, p.p. 3747 (2022) 44 fig. 7. the sem & the pore size for the anion exchange membrane before and after used. hussein h. abd-almohi al-khwarizmi engineering journal, vol. 18, no. 3, p.p. 3747 (2022) 45 4. conclusion the air cathode of mdc can be an effective method for sewage treatment, electric power production and water desalination, as oxygen has a great ability to reduce electrons. the external resistance and mixing processes in the desalination chamber can also have the ability to directly affect the efficiency of the mdc system the maximum power generation obtained 47 mw/m3 , the maximum cod removal was and the maximum desalination 40% water obtained 55% with 150 kω as external resistance after 48 h operation time. the results obtained in this study will enable the system to be developed to make it more efficient and sustainable for both sewage treatment processes, electric power production and desalination of salt water. 5. references [1] a. e. atabani, i. a. badruddin, s. mekhilef, and a. s. silitonga, “a review on global fuel economy standards, labels and 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[11] m. mehanna et al., “using microbial desalination cells to reduce water salinity prior to reverse osmosis,” energy environ. sci., vol. 3, no. 8, pp. 1114–1120, 2010, doi: 10.1039/c002307h. [12] k. s. jacobson, d. m. drew, and z. he, “efficient salt removal in a continuously operated upflow microbial desalination cell with an air cathode,” bioresour. technol., vol. 102, no. 1, pp. 376–380, 2011, doi: 10.1016/j.biortech.2010.06.030. [13] x. chen, x. xia, p. liang, x. cao, h. sun, and x. huang, “stacked microbial desalination cells to enhance water desalination efficiency,” environ. sci. technol., vol. 45, no. 6, pp. 2465–2470, 2011, doi: 10.1021/es103406m. [14] z. he, n. wagner, s. d. minteer, and l. t. angenent, “an upflow microbial fuel cell with an interior cathode: assessment of the internal resistance by impedance spectroscopy,” environ. sci. technol., vol. 40, no. 17, pp. 5212–5217, 2006, doi: 10.1021/es060394f. [15] q. wen, h. zhang, z. chen, y. li, j. nan, and y. feng, “using bacterial catalyst in the cathode of microbial desalination cell to improve wastewater treatment and desalination,” bioresour. technol., vol. 125, pp. 108–113, 2012, doi: 10.1016/j.biortech.2012.08.140. [16] k. s. jacobson, d. m. drew, and z. he, “use of a liter-scale microbial desalination cell as a hussein h. abd-almohi al-khwarizmi engineering journal, vol. 18, no. 3, p.p. 3747 (2022) 46 platform to study bioelectrochemical desalination with salt solution or artificial seawater,” environ. sci. technol., vol. 45, no. 10, pp. 4652–4657, 2011, doi: 10.1021/es200127p. [17] h. luo, p. e. jenkins, and z. ren, “concurrent desalination and hydrogen generation using microbial electrolysis and desalination cells,” environ. sci. technol., vol. 45, no. 1, pp. 340–344, 2011, doi: 10.1021/es1022202. [18] y. kim and b. e. logan, “series assembly of microbial desalination cells containing stacked electrodialysis cells for partial or complete seawater desalination,” environ. sci. technol., vol. 45, no. 13, pp. 5840–5845, 2011, doi: 10.1021/es200584q. [19] m. mehanna, p. d. kiely, d. f. call, and b. e. logan, “microbial electrodialysis cell for simultaneous water desalination and hydrogen gas production,” environ. sci. technol., vol. 44, no. 24, pp. 9578–9583, 2010, doi: 10.1021/es1025646. [20] l. huang, x. chai, g. chen, and b. e. logan, “effect of set potential on hexavalent chromium reduction and electricity generation from biocathode microbial fuel cells,” environ. sci. technol., vol. 45, no. 11, pp. 5025–5031, 2011, doi: 10.1021/es103875d. [21] x. zhang, w. he, l. ren, j. stager, p. j. evans, and b. e. logan, “cod removal characteristics in air-cathode microbial fuel cells,” bioresour. technol., vol. 176, pp. 23– 31, jan. 2015, doi: 10.1016/j.biortech.2014.11.001. ) 2022( 37-47، صفحة 3العدد، 18مجلة الخوارزمي الهندسية المجلد حسين حسام عبد المحي 47 ة توليد الطاقة وتحلية المياه باستخدام األكسجين ؛ كفاءاء خلية تحلية المياه الميكروبيةدراسة أد النقي في غرفة الكاثود **إسماعيلزياد طارق آل حسين حسام عبد المحي* مهند جاسم محمد *** اق العر / جامعة بغداد / كلية الهندسة الخوارزمي /حيائية هندسة الكيمياء االالقسم *،** العراق / جامعة بغداد /ندسةية الهكل /قسم الهندسة البيئة*** hdad.edu.iqhussein.abd1603@kecbu.uobagالبريد االلكتروني: * d.edu.iqbaghdaziadtarak@kecbu.uo** البريد االلكتروني: muhannadenviro@coeng.uobaghdad.edu.iq:ي *** البريد االلكترون ة الخالص ) الميكروبية التحلية تحليmdcخلية على قادرة ميا ) البة استخدام ه تم ، السابق في الصحي. الصرف مياه ومعالجة الكهربائية الطاقة وإنتاج حر تطبيق بسبب النفقات التشغيلية مرتفعة جدًا ، ومستويات منخفضة من الصالحية طويلة األجل وسمية عالية. تم يودًا على الالكاثودات الكيميائية ، والتي كانت ق جم / لتر والذي يمثل ٢٥١٥مع تركيزين من كلوريد الصوديوم في غرفة التحلية ) ١٥٠و ٥٠(kω قاومة الخارجية س المي ودراستخدام كاثود أكسجين نق ، وكان الحد األقصى لتحلية المياه المالحة ٣ميغاواط / م ٤٦و ٤٤تركيز المياه قليلة الملوحة ومياه البحر. تم الحصول على أعلى إنتاجية للطاقة والتي بلغت و ١٣، تم الحصول على kω ٥٠. عند kω ١٥٠جم / لتر على التوالي عندما باستخدام مقاومة خارجية قدرها ١٥جم / لتر و ٢٥٪) لكل من ٢٦و ٪٣١( ١٢ 3mw/m ي غرفة خلط ف جم / لتر على التوالي. تم ادخال مفهوم عملية ال ١٥جم / لتر و ٢٥٪ عند استخدام ٢٪ و ٢٠، وكان الحد األقصى لتحلية المياه ٪ ٥٥٪ و ٤٠ونسبة الملح المزيل في غرفة التحلية 3mw/m ٤٧و ٤٥التحلية لتحسين اداء النظام حيث تم الحصول على اعلى انتاجية للطاقة والتي بلغت غرفة التحلية من أجل زيادة لط في على التوالي. أظهرت هذه الدراسة نهجاً واعداً الستخدام عملية الخ kω ١٥٠جم / لتر و ٢٥جم / لتر و ١٥عند استخدام إنتاجية التحلية والكهرباء. (microsoft word \317 \346\323\307\343 \346\335\355\325\341 19-26) al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 16, no. 4, december, (2020) p. p. 1926 impact of using double layers perforated liners on the acoustic treatments of the combustor systems wisam s. hacham* faisal s. hiji** *department of mechatronics engineering/ al-khwarizmi college of engineering / university of baghdad ** hull university, hull, hu6 7rx, united kingdom *email: wisam@kecbu.uobaghdad.edu.iq **email: f.s.hiji-2017@hull.ac.uk (received 13 august 2020; accepted 25 october 2020) https://doi.org/10.22153/kej.2020.10.002 abstract the response of the combustor’s liner to the air-flow that passes through it is the key reason for the combustion chamber’s noise, hence, the instabilities of the chambers that decrease the mechanical efficiency of such sections by increasing its mechanical vibrations, which increases the failure rate that is created during the origination of the cracks that spread by the shakes that are produced by a series of high-level frequencies. accordingly, any work debating the impact of the context of the liners in the combustion chamber can provide grasping for the combustion noise generated by the undesirable vibrations, and benefits the industrial firms to design an ideal production procedure which increases the lifespan of the combustor. the goal of this work is to examine the influence of the acoustic treatment using a double layers cylindrical perforated liner on the acoustic transmission loss of gas turbines. the liners layout influences on this acoustic parameter were examined using experimental data gained by the insertion of full scale single and double patterns of perforated liners into the unique large scale acoustic wind tunnel at the acoustic research center at hull university. the experimental tests, using the designed acoustic signals, were established firstly without existing air cross-flow velocity (i.e., 0m/s), then by employing air with velocities interval 5m/s ranging between 10m/s to 25m/s. matlab script was used to simulate, analyze, and figure out the data collected by the insertion of single and double layer patterns of the perforated liner. the experiments demonstrated that, if the perforation acoustic treatments are applied, the acoustic transmission loss will decrease particularly obviously at higher level frequencies. furthermore, the results exposed that the air tunnel with the insertion of the liner with double layers reveals an improved perforation acoustic treatment with a percentage of about 19 % in most cases. keywords: acoustic treatment, acoustic wind tunnel, perforated liner, sound transmission loss (stl). 1. background the mechanical instabilities inside combustion systems such as gas turbines are extensively common. this phenomenon usually damages such systems, reducing their mechanical efficiency, and the lifespan of their components [1]. the more efficient turbines are the engines that have premixed combustion technology, which has combustion stability and low carbon emission. consequently, a stable operating engine has smooth and stable combustion during the operation periods for the combustors. different techniques are used to control the combustion instability for combustors, such as the fuel supplying optimization method by scheduling the fuel injection [2]. further, using an adjustment strategy for a combustor’s length. furthermore, the installation of a passive damping device such as a helmholtz resonator, quarteror half-wave tube, or the perforated acoustic liner(s) as applied wisam s. hacham al-khwarizmi engineering journal, vol. 16, no. 4, p.p. 1926 (2020) 20 in this work. however, using the first two approaches be contingent on the weight and space limitations of the combustors [3]. the perforated liner is used as an acoustic damper by absorbing the pressure fluctuations inside the combustion chambers, where using the liner as a damper involves vortex generation over the border of its perforations [4]. nowadays, there are respective studies that have revealed outstanding summaries on the progress, status, and challenges of the application of the perforated liner as an acoustic damper for different combustor systems [5]. however, most of those studies have been primarily focused on the simulation and experimental characterization of the single-layer liners. to reduce an operating temperature of metalwall below the trueor engineering-strength borders, the thermal loads on the combustor's wall of the aero-engines, to ensure in other gasturbines, is reduced by applying multi-perforated liners [6]. furthermore, a double-layers liner is thought to supply better patterns for an acoustic transmission loss tl than the single-layer liner [5]. therefore, the existing literature of this field of knowledge needs more researches to enrich it; the focus should be oriented to cylindrical doublelayers perforated liners with the context of windtunnel experimental tests instead of simulation and numerical analysis. the sound transmission loss (stl) is the parameter used to count the amount of sound energy that is traveling via the acoustic treatment devices, furthermore, it is an accumulation for the amount of the sound acoustic pressure wave intensity that propagates outwards from the sound source, where the intensity of the sound wave can be reduced by increasing the range of wave attenuation and/or wave spreading [7]. consequently, to decrease the power of sound crossing inside any wind-tunnel, it is prevalent to stratify single and/or double layers of perforated liners. stratifying such liners with different perforation styles, percentage of holes, and sizes in the acoustic treatment will impact the amount of transmission loss of sound [8]. there are prime dilemmas that emerge with the use of an acoustic treatment in the installation of the wind-tunnel, the tuning is one of which, where the unwanted level of frequency of sound pressure fluctuation is most effectively macerated or attenuated to the required frequency, by making the sound frequency of the resonant is as close to the required frequency as much as manageable, through changing specifications concerning the geometry of the liner such as the percentage of its porosity (i.e., numbers and size of holes), and its plate thickness [8]. a provided controlled air-stream that is produced by the wind-tunnel can be used to help examine the effects of the movement resistance or drag force, which arises from the air on any object impacted by the air-stream, where it does not matter whether the stationary selected model can withstand the high force of the wind pressure [9], or whether or not the model that is being tested is styled by a technique permits it to easily move through a stream of air or not as it conducted in this experimental work. calculating stl for different frequencies assists in showing some parameters such as the sound transmission loss distribution [10]. the perforated liners are typically tubular cylinders in a single layer, double layer, or multiple layers, which have slots or holes with small diameters created before operating and assembling the cylinder itself [11]. the size of layers and their numbers help figure out the durability of the liner and its efficiency to withstand strong vibrations. however, a liner with a single-layer can be applied for long operating time conditions, while a multiple-layers liner has a priority when operating in high heat-load conditions. meanwhile, they are all used in combustor techniques to absorb the power of the incident acoustic waves. the sound transmission loss indicates the total intensity reduction of a sound wave-front power through sound noise propagation away from the source. furthermore, as common in most acoustic applications, the intensity reduction as a sound wave-front propagates through a certain design [3]. this experimental work attempts to enrich the existing available works by performing experimental investigations through a wind-tunnel with the context of singleand double-layers cylindrical perforated liners. a brief search shows that most of the available researches focus on the characterization of cylindrical liners that consist of a single-layer, using computational and numerical simulations and analyses. this work addresses a different approach to enrich the existing available literature of this field of knowledge. the significance of this work is to illustrate how increasing the liner layers can eventually reduce harmful vibration and ultimately raise the efficiency of combustors, through analyzing some key physical parameters like layout combinations of the singleand double-layers perforated liners and also the velocity of the air-flow, by investigating and wisam s. hacham al-khwarizmi engineering journal, vol. 16, no. 4, p.p. 1926 (2020) 21 optimizing the double-layers perforated liners through acoustic experimental investigations. therefore, these concepts will provide the performance-enhancing of the issues of the combustion chamber design. 2. methods 2.1 experimental methodology two strategies that have been experimentally attempted during this work are the acoustic experiments using the wind tunnel, which has been arranged alongside the single-and doublelayers cylindrical perforated liner. in the same procedures and setups for the large scale acoustic wind-tunnel, the experimental tests with the presence of both full-scale doubleand single-layer perforated liner patterns, which are (inner4+outer2) and (inner1), respectively, as shown in table 1, which was performed using a noise generator, loudspeaker, amplifier, four microphones, a computer connected to data acquisition apparatus and the sound card, and a single processing unit. the specifications of the acoustic treatment that have been employed in the experimental tests are shown in table (1). it can be seen that the outer and inner layers of the double liner were manufactured in different porosity distributions, sizes, and thicknesses. the arrangements and configurations of the perforated liners are used in this work are illustrated in figures (1) and (2). after starting-up of the tunnel, the sucked air by the fan of the tunnel is brought up to the required velocity and will be guided using an external vent to pass it through the intake partition to the perforated liners that provide a terminus for the echoic across its walls while it moves out from this partition (i.e., removing the sound noise from the fan itself and from the flow of air which travels past the fan into the main partitions of the tunnel). then the sound will be generated and added as a white noise signal to the air-stream as it passes through the position of the loudspeakers, which connects to a noise generator via an amplifier, before it propagates as a sound wave downstream towards the rest of the tunnel's straight section. the loudspeakers were installed in different sizes to provide different ranges of frequency at this partition. then, the stream of air that accompanied the sound waves passes through the main full-scale perforated liner, which is clamped securely either side in place far enough downstream of the tunnel to permit the plane sound waves to travel through a fully developed flow. consequently, the sound was terminated and removed again before exiting the tunnel through the tunnel's rear vent. the experimental tests were firstly started by collecting and taking readings for the condition of no airflow (i.e., 0m/s), using agilent data capture software installed in the computer available for this purpose. then the velocity was set by measurements for the cross-flow velocity, starting at 10m/s up at intervals of 5m/s to a maximum of ٢٥m/s. likewise, the program of agilent data capture was used to take 30 readings for each stream of airflow. fig. 1. illustrates the layout of a single-layer perforated liner pattern utilized at this work. fig. 2. illustrates the layout of a double-layers perforated liner pattern utilized at this work. wisam s. hacham al-khwarizmi engineering journal, vol. 16, no. 4, p.p. 1926 (2020) 22 2.2 theoretical methodology the performance of the transmission loss for certain acoustic materials differs greatly with the level of the frequency applied, thus, stl can be marked as the ratio of the level of a sound power transmitted through the material during an acoustic treatment to the level of an incident sound power [12]. stl � 20log �� � … (1) tf � �� �� … (2) where the transmission factor is represented by tf, while the transmitted and incident sound powers are represented by (pt) and (pi), respectively. in general, the decibels (db) scale mathematically terms the measurement of the sound transmission loss. the sound powers are demonstrated in figure (3). 3. results using the four microphones installed on the single-and double-layers perforated liner, the procedure of the experimental tests illustrated in detail above was performed and carried out to acquire the sound transmission loss against the level of the frequency applied. then, the test's data was processed to gain the pertinent diagrams. the data of sound transmission loss against the level of the frequency were plotted in figures (4) to (8). the presented results are the average of thirty scenarios of the experimental tests with and without the context of the cross-velocity of airflow through the singleand double-layers perforated liners, which are figured out as illustrated in table (1). 4. discussion as shown in figure (4), it is clear that the magnitude of the sound transmission loss is highly dependent on the level of the frequency applied. additionally, it can be recognized that at 225hz the liner decreases the level of incident sound power by 10db. furthermore, at roughly 660hz and above, the tunnel's liner did not decrease the level of the incident sound power at all. furthermore, it can be accepted that the results have outlandish dicrotic notches, particularly recognized at frequency levels less than 260hz. basically, there is a lack of satisfaction with this behavior, especially in case of no presence of the air crossflow. this behavior can be attributed to the rate at which sound power decays in a liner during the sound attenuation process for the intensity of the acoustic wave either by sound power absorption or by the sound power reflection. the hole (acoustic treatment) decreases the effective sound transmission loss, particularly distinguished at a higher level of the frequencies [12], as shown in figures (4) to (8). as the hole (acoustic treatment) gets larger, the liner's effect was not introduce dramatically as at the initial perforation holes, but was especially introduced at the higher level of the frequencies. fig. 3. demonstrates the sound powers through the perforated liners. the (ptransmitted), (pabsorbed), (preflected), and (pi) represents the transmitted, absorbed, reflected, and incident sound powers, respectively. table 1, illustrates the characteristics of the double-layers and single-layer perforated liner. liner perforations cylinder internal diameter (mm) thickness (mm) external diameter (mm) length (mm) no. * diameter (mm) inner 1 160.65 1.6 163.85 524 3402 0.725-0.875 inner 4 162.14 2 166.14 524 2256 0.775-0.975 outer 2 176.6 1.6 179.8 524 384 3.525-3.675 * refers to a number of rows and a (holes/row) for each liner. for inner1 they are 54 and 63, respectively. for inner4 they are 47 and 48, respectively. for outer2 they are 16 and 24, respectively. pincident preflected pabsorbed ptransmitted wisam s. hacham al-khwarizmi engineering journal, vol. 16, no. 4, p.p. 1926 (2020) 23 the style of staggering used in acoustic treatments is the most widespread style. additionally, its structural strength more than other patterns of the perforation as concluded by [18]. furthermore, the increase of the perforation orifices chamfering decreases the effective thickness of the hole (i.e., the edge profile of the hole), as concluded by [19]. the data presented in figures (4) to (8) clearly show an obvious slow-down pattern in the decay of the sound transmission loss of the acoustic power with an increase in the magnitude of the air cross-flow velocity. the decay level of this parameter gradually rises above the level of slowdown of the 10m/s tests. consequently, the larger the velocity of air cross-flow, the stronger rise in decay style, thus, for this work, it can be concluded that the sound transmission loss for the 10m/s is preferable. finally, at least it is clear that the air-tunnel with the presence of the double-layers liner shows better sound transmission loss results. this may depend on the number of the perforation holes and the style of the distribution of those holes at the same liner or may be due to the layers thickness and/or the gap thickness between the two layers used. it concludes that using a liner with the context of double-layers may produce a better result than those gained by applying a liner with the context of a single-layer. 5. conclusions the sound transmission loss helps on how to determine and improve the acoustic properties of acoustic materials, and it can be a perfect scale with which to inspect the efficacy of a tunnel in decrease of sound energy transmission, using the small perforation holes that extremely decrease the transmission loss parameter. depending on the findings of this work, it can be stated that it is needful to use a typical perforated liner to efficiently remove or control the sound noise that is originated from the dynamical vibrations to reach the noise to a specific level of the db scale. additionally, increasing the velocity of the air cross-flow leads to at least the slowingdown in the decay which occurs in the sound transmission loss magnitude. moreover, in terms of the sound transmission loss, the air-tunnel revealed better results with the presence of the liner composed by double-layers. fig. 4. the acoustic transmission loss versus frequency. the data were collected with air cross-velocity equal to (0m/s) using the perforated liners. wisam s. hacham al-khwarizmi engineering journal, vol. 16, no. 4, p.p. 1926 (2020) 24 fig. 5. the acoustic transmission loss versus frequency. the data were collected with air cross-velocity equal to (10m/s) using the perforated liners. fig. 6. the acoustic transmission loss versus frequency. the data were collected with air cross-velocity equal to (15m/s) using the perforated liners. fig. 7. the acoustic transmission loss versus frequency. the data were collected with air cross-velocity equal to (20m/s) using the perforated liners. wisam s. hacham al-khwarizmi engineering journal, vol. 16, no. 4, p.p. 1926 (2020) 25 fig. 8. the acoustic transmission loss versus frequency. the data were collected with air cross-velocity equal to (25m/s) using the perforated liners. 6. references [1] kim, 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[11] dai, x. and aurégan, y., 2016. acoustic of a perforated liner with grazing flow: floquetbloch periodical approach versus impedance continuous approach. the journal of the acoustical society of america, 140(3), pp.2047-2055. [12] heckl m., the tenth sir richard fairey memorial lecture: sound transmission in buildings, j. sound vib. 77(2): 165-189, 1981. [13] lahiri, c., 2014. acoustic performance of bias flow liners in gas turbine combustors, berlin: technical university of berlin. [14] temiz, m. a., arteaga, i. l. & hirschberg, a., 2015. sound absorption measurements for micro-perforated plates: the effect of edge profile, maastricht: euronoise 2015. �� 4، ا���د����16 ا���ارز � ا���� �� ا���� و �م ��ي ���� �� ، 26 -19)2020( 26 ��3/�ر.���ت ا�2�ز� ��01 ا /��ام .-�,�ت *دو(� )'&� %�$ ا��!�#" ا�!� �� **�7!6 ���5 ��4 *و �م ��ي ���� ��اد*��� ھ���� ا ������و���/ ��� ا ����� �ا &%ارز "/ !� �� **!� �� ھ�ل ، ھ�ل ، hu6 7rx ، ا ����� ا �()�ة ** wisam@kecbu.uobaghdad.edu.iq -�,�ا ا/ �(�و�": * hull.ac.uk-f.s.hiji@2017ا -�,� ا/ �(�و�": ** ا��8�� ا �?�ر ا �<��" =%>�ء ا (" ���; ��: ا ���5-���9ت ا �(�85 دا01 �5�7 ا/1(�اق 5" ا �)� �ت ا (%ر����� و��2 ا ا �%اء ��2 ا (�ا01�(-� , " �) ��ا/����ر ، وز,�دة اھp)از ا ��%��ت، وز,�دة ��ل ,oدي إ l ا�&�kض 5" أداء ا ��(ك �hم ا�(�fار ا/@(�اق. وھdا ,��2 أنa-� "5 ا ا/@(�اق و ��-a ا�(�qر ا (8fq ��)�ك ا �������" r��� ي ,)�ث اd از اp2 ا/ھ( � ��tu� ��5 l دي إo, يd اء ا�!vا w���, �,�f� ن أيx5 ،" �) ��(�ددات �h ��. و 2h � %), ي ,��2 أنd ا/@(�اق، وا r�y< 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0، �5%ف ,(�-a 5" ا�&�kض ��h )�ل ھ% ا �� �0�q �1ص ��h ا (�ددات اl�hn. أو>)ا afz ا/�(�ا<" اnو " p<ا واd%ا<"، وھ� ,�ح ا� 8 اk� أن r>�)� ا k ���9ق ا��� ` .ا ?%�" ا/ر��لا �pدو!� ,�r>�)� "9 أ@ 2 0=5��f5 ]ان al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 5361 (2014) heterogeneous photocatalytic degradation for treatment of oil from wastewater yasmin a. mustafa* abeer i. alwared** mothana ebrahim*** *,**department of environmental engineering/ college of engineering/ university of baghdad ***ministry of environment *email: yasmen.mustafa@gmail.com **email: abeerwared@yahoo.com ***email: muthanna_env@yahoo.com (received 21 january 2014; accepted 20 may 2014) abstract in the present study, advanced oxidation process / heterogeneous photocatalytic process (uv/tio2/fenton) system was investigated to the treatment of oily wastewater. the present study was conducted to evaluate the effect of hydrogen peroxide concentration h2o2, initial amount of the iron catalyst fe +2 , ph, temperature, amount of tio2 and the concentration of oil in the wastewater. the removal efficiency for the system uv/tio2/fenton at optimal conditions and dosage (h2o2 = 400mg/l, fe +2 = 40mg/l, ph=5, temperature =30 o c, tio2=75mg/l) for 1000mg/l load was found to be 77%. aluminum foil cover around the reactor and air bubbling were utilized in the experiments of photo fenton uv/ h2o2/fe +2 homogeneous and heterogeneous systems in order to improve the removal efficiency. the removal efficiency was improved to 81% for uv/tio2/fenton system . the reaction was found to be of a first order throughout the systems. keywords: oily wastewater, advance oxidation process, heterogeneous process, aluminum foil. 1. introduction oil is one of the important contaminants in water and causes the wastewater problems in environments. in practice, this can form various types of oily wastewaters; for instance, soluble oil in water, emulsion with or without surfactants or floating film [1]. oils that are found in contaminated water can be grouped into [2]:  light hydrocarbons including light fuels such as gasoline, kerosene and jet fuel.  heavy hydrocarbons, fuels and tars including the crude oils, diesel oils, gas oil and asphalt.  lubricants and cutting fluid that generally falls into two classes: non-emulsifiable oils such as lubricating oils and greases, and emulsifiable oils such as water soluble oils, emulsifiable oils may contain soap, or various other additives. the volume of diesel/gas oil contaminated wastewater from petroleum filling stations has increased in line with the number of such stations required to cater for the growing number of vehicles. according to data provided by international energy agency (iea), the world consumption of diesel oil increased during the period 1990 to 2003 from 454,747 to 684,022 million liters. in iraq there is 507 car-wash facilities (except kurdistan), (ministry of environment report 2011) and some of them discharge its wastewater (almost emulsifiable oils) to sewer systems without treatment. mailto:yasmen.mustafa@gmail.com yasmin a. mustafa al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 5361 (2014) 54 also as a result of human activities, there are many accidental discharges of hydrocarbon oil to the natural environment during its processing, transportation and storage. photo in fig. 1 , illustrate oil contaminated wastewater in iraqi stream. diesel /gas oil causes eye and skin irritation in humans, but otherwise its effects on humans are considered to be poorly investigated [3]. diesel is considered to be harmful and possibly carcinogenic to humans and it contains pahs that create a risk for human health because of their carcinogenic, mutagenic and teratogenic properties [4]. standards and regulation were adopted for discharge of oily wastewater into surface water or sewage systems. these regulations may vary from country to country, and even within a country itself. the allowable hydrocarbons and its derivatives discharge into water bodies about 10 mg/l in iraq [5]. advanced oxidation processes (aops) have been investigated for the oil-contaminated wastewater treatment as an alternative to conventional treatment techniques. aops are characterized by the use of highly reactive intermediates, hydroxyl radicals (ho•), which attack the organic pollutants in the wastewater and mineralize them. advanced oxidation processes (aops) have the advantage of rapid oxidation of pollutants to harmless end products. such processes include homogenous processes such as fenton’s reagent, h2o2 and ozone and heterogeneous photocatalysis using semiconductors such as tio2 and zno [6]. fig. 1. surface water oil contaminated in a al fataha . the principle of heterogeneous photocatalysis is based on the activation of a semiconductor particulate material (cds, tio2, zno etc.) by the action of radiation with an appropriate wavelength. this activation is achieved with the absorption of photons by the semiconductor particle possessing enough energy to promote the conduction of an electron (e − ) from its valence band (vb) to the conduction band (cb) (a transition called band gap energy), creating holes in the valence band (h + ) that will act as oxidizing sites[7] . the treatment of water produced from oil fields was studied via a photocatalytic process using tio2/uv, with the addition of h2o2. chromatographic analyses showed the complexity of the wastewater, and most of the compounds present in the medium, remained unidentified. however, a considerable reduction in chromatogram peaks can be observed, showing pollutant degradation. they observed that addition of h2o2 in the photocatalytic process was unnecessary and even undesirable, owing to the corrosive and damaging effects of this substance on the catalysts (tio2) [8]. tio2/uv process was used to degrade the organic pollutants of a refinery wastewater by a circulating photocatalytic reactor. in 2009, tony et al.[9] studied the combined fenton/uv augmented with tio2 and zno for mineralization of diesel-oil wastewater emulsion. the results show that the process is sensitive to the concentrations of the fe+ 2 , h2o2 and tio2 or zno, but the process performs well over a wide ph range. the optimum conditions were found to be: 40 mg/l, 400 mg/l and 500 mg/l for fe+ 2 , h2o2 and tio2 respectively and a ph of about 8.0. under such conditions, with air being bubbled through the emulsion, an 84% reduction in the diesel oil-water emulsion cod concentration was achieved. the fenton/uv process (without any tio2 or zno) achieved a 61% cod reduction. they illustrate that the issues relating to tio2 and fe residuals in the wastewater effluent require further study. the objective of this work is to study the effectiveness of the aops in the degradation of oil in wastewater. the aops selected to carry out this study was heterogeneous photo-assisted system (uv/tio2/fenton). yasmin a. mustafa al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 5361 (2014) 55 2. materials and methods 2.1. reagents commercial gas oil was used in this study as the model pollutant for the degradation of oil from wastewater by aop. gas oil was analyzed in petroleum research and development center / ministry of oil. the chemical compositions are paraffins 62.5%, aromatics 18.7% and naphthenes 18.8%. the paraffinic fraction composition of gas oil was identified by gas chromatography and revealed more than 66 alkane compounds, fig.2. from this figure it can be observed that gas oil has a higher relative concentration in c9, c11, c12, c13, c14 and c15. the functional groups present in gas oil were detected by ftir analysis, fig. 3. table 1 shows all the chemicals that used in the experiments. all the samples were prepared by dissolving requisite quantity in distilled water. the ph of the solution was adjusted by using h2so4 solution. fig. 2. the paraffinic fraction composition of gas oil. fig. 3. the functional groups of gas oil detected by ftir analysis. yasmin a. mustafa al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 5361 (2014) 56 table 1, list of chemicals used. 2.2. equipments the experiments were carried out in a batch mode laboratory-scale reactor, fig.4 .the reactor consists of pyrex glass cylinder 3 litter volumes mounted at magnetic stirrer with heater (msh300n, boeco, germany). uv radiation (254 nm) was generated from uv lamps (tuv 11w 4p-se, philips, england), which was fixed vertically at the top of the reactor. the lamp was totally immersed in the cylindrical reactor. uv lamp was sheathed in quartz sleeve for protection. the distance between the lamp and the reactor was fixed to be 5 cm to ensure maximum light irradiation [10]. the turbidity of the solution for three experiments was measured using turbidity meter (hanna microprocessor, italy). initial ph of solution was monitored using a ph meter from (wtw co., german, inolab 720). 2.3. experimental procedure the procedure was performed as follows: the desired concentration of gas oil (500-2000) mg/l was prepared and the ph was adjusted before adding the reagents by adding a dilute h2so4 solution in the reactor. the fenton reagents were introduced to the solution by adding ferric chloride (10-100 mg/l) and then the hydrogen peroxide (100-800 mg/l). the solution was then subjected to stirring using a magnetic stirrer at 200 rpm for 150 min. the heater was adjusted at the required temperature. samples at a regular time intervals (30 min.) were taken for cod analysis. 2.4. analysis chemical oxygen demand of samples was analyzed by using cod photometer. the appropriate amount of sample (0.2ml) was introduced into commercially available digestion solution (hr-rang: 0-15000mg/l) containing potassium dichromate, sulfuric acid and mercuric sulfate. the mixture was then incubated for 120 min at 150°c in a cod reactor (model rd-125, lovibond company, germany). after oxidation is complete, the cod concentration was measured colorimetrically at 605 nm using a dr/2010 spectrophotometer (model rd-125, lovibond, germany). (a) (b) fig. 4. laboratory scale batch reactor (a) schematic diagram of batch reactor, (b) photograph of batch reactor. compound formula vender hydrogen peroxide h2o2 scharlau (30 % wt/wt) ferrous chloroide tetrahydrate fecl2.4h2o bdh (97% purity) sulfuric acid h2so4 riedel-dehaen (99 % purity) yasmin a. mustafa al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 5361 (2014) 57 3. results and discussion 3.1. effect of initial titanium dioxide (tio2) concentration from our previous study [11] , the optimal conditions for homogenous process were (h2o2= 400 mg/l, fe +2 = 40 mg/l, temperature = 30 o c, oil concentration =1000 mg/l and ph = 3) and the removal efficiency for the system uv/ h2o2/fe +2 at that optimal conditions was found to be 72%. different concentrations of titanium dioxide (50, 75, 100 and 300) were used to show its effect on uv/ fenton system at optimum conditions, fig.5, from this figure it can be noticed that the removal efficiency increases to reach a maximum of 61% at 75 mg/l of tio2, then it tends to decreases to reach 27% at 300 mg/l tio2. the increase in removal efficiency can be explained by the increase in the number of oil molecules that were absorbed by the tio2. moreover, when tio2 is exposed to uv light, the light induction generates a hole in the valence band and an electron in the conduction band. the oxidation of adsorbed water or hydroxyl ions by holes in the valence band at the excited surface produces the hydroxyl radicals. the resultant radicals degrade the oil molecules which increases the removal efficiency. however, increasing the tio2 dosage beyond an optimal value has a negative effect on the degradation process. this is due to the fact that excess tio2 particles increase the opacity of the suspension there by decreasing the light penetration into the solution, resulting in a reduction in the number of hydroxyl radicals, this explanations were also mentioned by [12]; [9]. fig. 5. effect of initial titanium dioxide (tio2) concentrations on oil degradation by photocatalytic system at h2o2=400 mg/l, fe +2 =40 mg/l, temp. = 30 o c, oil conc. = 1000 mg/l and ph=3. 3.2. effect of the initial ph in order to study the effect of the initial ph in photocatalytic process, different values of ph (3, 4, 5, 6 and 8) were carried out at h2o2 = 400 mg/l, fe +2 = 40 mg/l, tio2 = 75 mg/l and temperature=30 o c. ,fig. 6, from these figure it can be noticed that the removal efficiency increases to reach a maximum of 77% at ph=5. the effect of ph cannot be generalized, it depends on the electrostatic interaction between the catalyst surface and the pollutant. some authors recognized that the pollutants, which undergo hydrolysis under alkaline conditions, may show an increase in the rate of photocatalytic oxidation with an increase in the ph [13] ;[14]. the pollutants, which are weakly acidic, rate of photocatalytic oxidation increases at lower ph due to an increase in the extent of adsorption under acidic conditions [15]; [16] . in 2009 tony et al.[9] have reported that the ph had marginal effect on the extent of degradation for diesel oil water emulsion over the range of ph studied in their work, the optimum ph for photocatalytic oxidation was found to be 8.0. fig. 6. effect of the initial ph on oil degradation by photocatalytic system at h2o2=400 mg/l, fe +2 =40 mg/l, temp. = 30 o c, oil conc. = 1000 mg/l and tio2=75 mg/l. 3.3. effect of air bubble and aluminum foil the performance of inducing air bubbles into the reactor and using aluminum foil cover around the reactor on the removal efficiency of oil were studied , fig. 7. it can be noticed from fig.(7) that the removal efficiency increases from 77% to yasmin a. mustafa al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 5361 (2014) 58 80% when using aluminum foil cover and reaches to 81 % when using air bubbling and aluminum foil. aluminum foil cover can enhance the degradation efficiency because it reflects irradiation exerting by the outer wall of the reaction vessel. when air is bubbled into solution, the o2 can scavenge the photon-produced electrons on the tio2 surface, thereby improving the overall reaction rate. in addition, the presence of o2 in air noticeably works as an oxidizing agent for the organic molecules present in the solution [17]. fig. 7. degradation of oil by heterogeneous photocatalytic system at h2o2=400 mg/l, fe +2 =40 mg/l, temp. = 30 o c, oil con. = 1000 mg/l, tio2=75 mg/l , ph=5 and irradiation time =150 min. 3.4. reaction rate constant for homogenous and heterogeneous photocatalyst the experimental data for diesel oil degradation can be fitted according to pseudofirst-order and pseudo-second-order. the linearized form of pseudo-first-order and second-order kinetic models can be given in equations (1) and (2): …(1) … (2) where codo is the initial concentration of gas oil and cod is the concentration at irradiation time t , k and k1 are the pseudo-firstand pseudosecond-order rate constants in min -1 and l.mg -1 min -1 respectively , t is the irradiation time (in min). a plot of , and versus time for each experiment lead to a straight line whose slope is k and k1 respectively. the regression analysis of the concentration curves versus reaction time indicates that the decomposition rate of this compound could be described by first order kinetics. the results are shown in table2. 4. conclusion uv/tio2/fenton(heterogeneous hotocatalysis) was used to examine the performance of aop for the degradation of oil in wastewater .the reaction was influenced by the input concentration of h2o2, the amount of the iron catalyst fe +2 , ph, temperature, the amount of tio2 and the concentration of oil in the wastewater. the reaction was found to be of a first order throughout the systems. the removal efficiency for the system uv/tio2/fenton at optimal conditions and dosage (h2o2 = 400mg/l, fe +2 = 40mg/l, ph=5, temperature =30 o c, tio2=75mg/l) for 1000mg/l load was found to be 77%. to improve the performance of aops, aluminum foil cover around the reactor and air bubbling were utilized. the removal efficiency was improved to 81% for uv/tio2/fenton systems respectively. yasmin a. mustafa al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 5361 (2014) 59 table 2, pseudo-first-order, pseudo-second-order rate constants (effect of aluminum foil and air bubbles in homogeneous system and heterogeneous system) homogenous process; h2o2=400mg/l , fe +2 =40mg/l , temp.=30 o c , ph=3 treatment removal efficiency first order second order kx10 3 min -1 r 2 k1x10 6 lmg -1 min -1 r 2 with alumn. foil 75 16.1 0.930 15.3 0.914 with alumn. foil + air bubble 79 17.5 0.911 19.2 0.922 heterogeneous photocatalyst ; h2o2=400mg/l , fe+2=40mg/l , temp.=30oc , ph=5 ,tio2=75mg/l treatment removal efficiency first order second order kx103min-1 r2 k1x106lmg-1min-1 r2 with alumn. foil 80 18.4 0.926 18.5 0.918 with alumn. foil + air bubble 81 20.2 0.927 25.0 0.891 5. references [1] painmanakul , p. , kongkorn , k. , and chawaloesphonsiyam n. , 2009 , "treatment of oily wastewater by fibrous coalescer process : stage coalescer and model prediction", world academy of science , engineering and technology , vol. 34, pp. 317-322. 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[16] andreozzi, r., caprio, v., insola, a., longo ,g.and tufano, v., 2000 ,"photocatalytic oxidation of 4-nitrophenol in aqueous tio2 slurries: an experimental validation of literature kinetic models", j. chem. tech. biotech, vol. 75, p.131. [17] barakat , m.a, tseng, j.m. and huang, c. p., 2005,"hydrogen peroxide assisted photocatalytic oxidation of phenolic compounds", appl. catal., b., vol. 59, p. 99–104. (2014) 5361، صفحة 3، العدد10دجلة الخوارزمي الهندسية المجلم ياسمين عبد العزيز 61 متجانس الغير الضوئي التحفيز طريقة باستعمال الملوثة المياه من الزيوت ازالة ***مثنى ابراهيم ** عبير ابراهيم الورد *ياسمين عبد العزيز مصطفى جامعة بغداد / ة الهندسةكلي /قسم الهندسة البيئية**، * وزارة البيئة*** yasmin.mustafa@gmail.com:البريد االلكتروني* abeerwared@yahoo.com :البريد االلكتروني** ahoo.commuthanna_env@y:البريد االلكتروني*** الخالصة . الملوثة بالزيتلمعالجة مياه الصرف (uv/tio2/fenton) الغير متجانسة / تم في هذا البحث التحقق من امكانية استخدام طريقة األكسدة المتقدمة المحفزالحديد التركيز االبتدائي اليون، h2o2 بيروكسيد الهيدروجي تم دراسة تاثير تركيز + f 2 تركيز مادة ودرجة الحرارة، والدالة الحامضية، tio2لتر وتركيز الحديد المحفز /ملغم 044=كانت عند تركيز بيروكسيد الهيروجين إزالة تم التوصل الى ان اكفئ. الملوثةفي مياه زيتاالولي لل تركيزوال / ملغم 0444=عند تركيز اولي للزيت لتر / ملغم 55كسيد التيتانيوم درجة مئوية وتركيز ثاني او 04=و درجة حرارة 5=لتر ودالة حامضية /ملغم 04= %.55لتر بلغت وبذلك ازدادت نسبة االزالة للنظام، ى ضخ الهواء مع المواد المتفاعلةتم تغطية جدار المفاعل بورق االلمنيوم اضافة البهدف زيادة الكفاءة uv/tio2/fenton81 لتبلغ . % mailto:yasmin.mustafa@gmail.com mailto:abeerwared@yahoo.com al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 4, no. 2, pp 2736 (2008) time series analysis of total suspended solids concentrations in euphrates river in al-nasria province prof. dr. rafa al-suhaili ass.lecturer. tariq j.al-mosewi environment engineering deptartement/ college of engineering/ university of baghdad (received 6 may 2007; accepted 3 april 2008) abstract the monthly time series of the total suspended solids (tss) concentrations in euphrates river at nasria was analyzed as a time series. the data used for the analysis was the monthly series during (1977-2000). the series was tested for nonhomogenity and found to be nonhomogeneous. a significant positive jump was observed after 1988. this nonhomogenity was removed using a method suggested by yevichevich (7). the homogeneous series was then normalized using box and cox (2) transformation. the periodic component of the series was fitted using harmonic analyses, and removed from the series to obtain the dependent stochastic component. this component was then modeled using first order autoregressive model (markovian chain). the above analysis was conducted using the data for the period (1977-1997), the remaining 3-years (1998-2000) of the observed data was left for the verification of the model. the observed model was used to generate future series. those series were compared with the observed series using t-test. the comparison indicates the capability of the model to produce acceptable future data. key words: total suspended solids, nonhomogeneous, periodic component, and dependent stochastic. introduction water quality express the suitability of water to sustain various uses or processes, such as drinking water, irrigation water and nature conservation. solids can be dispersed in water in both suspended and dissolved forms. solids suspended in surface water may consist of inorganic particles or of immiscible liquids. domestic wastewater usually contains large quantities of suspended solids. suspended solids material may be objectionable in water for several reasons. it is aesthetically displeasing and provides adsorption sites for chemical and biological agents. suspended organic solids may be degrading biologically resulting in objectionable by products. biologically active suspended solids may include disease causing organisms as well as organisms such as producing strain of algae. during the last 25 years, time series analysis had become one of the most important and widely used branches of mathematical statistics. the technique of time-series analysis uses estimated statistical parameters to build a mathematical model. this model is capable of describing the evolution of possible sequences of events in time, at the site of observations, which have the same statistical properties as the historical sample. in this research, the data of tss in euphrates river will be utilized to build the mathematical model to predict the future concentration. numbers of projects were by now under construction in the southern of iraq after march 2003, such as water treatment plants and projects related to restoration of marshes and irrigation projects. the modeling of tss could be used to predict future values, that are useful in the operation of such project. moreover these data are useful also in planning, design of new projects. garry l.grabow et,al. (4) used weekly total suspended solids data to build a mathematical model. the data were collected from a measurement station located downstream of a dairy farm. two types of statistical methods were used to detect the changes in the tss concentrations, ancova and anova. zhiyong huang and hiroshi morimoto(8) designed a structure of input/mixing/output model rafa al-suhaili al-khwarizmi engineering journal, vol. 4, no. 2, pp 27-36 (2008) 28 (called it the three-step model) and represented each process of material input, mixing and output by a stochastic numerical methods. data of bod and do concentrations of river cam used to build the model. the stochastic numerical methods applied in this paper are discrete time approximation methods. additional equations representing mixing processes and biochemical reactions also used in model. the researcher concluded that the theory of stochastic differential equations is a beneficial tool for studying water pollution. kadri yurkel and ahmet kurunc (3) had analyzed the daily discharge data of each month from three gauge stations on cekerek stream for forecasting using stochastic approaches. initially non-parametric test (mann-kendall) was used to identify the trend during the study period. the two approaches of stochastic modeling, arima and thomas-fiering models were used to simulate the monthly-minimum daily discharge data of each month. the error estimates (rmse and mae) forecasts from both approaches were compared to identify the most suitable approach for reliable forecast. the two error estimates calculated for two approaches indicate that arima model appear slightly better than thomas-fiering model. however, both approaches were identified as an appropriate method for simulating the monthlyminimum daily discharge data of each month from three gauge stations on cekerek stream. the use of time series analysis (stochastic analysis) in generating possible future suspended solids concentrations assumes that those concentrations are extracted from a common statistical population, and that the recorded historical data forms a sample from this population. generally, a hydrologic time series may consist of four components depending on the type of variable and the averaging time interval. in seasonal tss concentration series four components may exist and the tss is considered to arise from a combination of those components, which are termed the jump component (jt), trend component (tt), periodic or cyclic component (pt) and stochastic or random component (t).these components may be formulated by: tsst= jt +tt +pt +t …(1) the first three components represents the deterministic part of the process while the fourth component represents the non-deterministic part, therefore those three components should be detected and identified by suitable formulations and decomposed from the stochastic component. methodology the procedure used for data analysis may be summarized by the following steps: 1filling-in of missing data data of monthly tss concentration in euphrates river were mentioned in reports of the ministry of water resources. these reports indicated some months with missing data in irregular years. table (1) shows the missing readings in tss in a period from 1977 to 1983. filling-in the missing data was performed by using the regression relations method. 2test and removal of non-homogeneity the modeling process required a set data to be homogenous. hence, the first step before starting the analysis is to test the homogeneity of the data series. if the test indicates non-homogeneity, then this non-homogeneity should be removed. this was achieved by plotting the average monthly data and computing the annual mean and standard deviation for each year then using the spilt-sample approach which divides the entire sample into two sub-samples. then testing the differences between the means and standard deviations of these two sub-samples at the 95 percent probability level of significance using the t-test method. the data were tested for non-homogeneity and found to be non-homogeneous at year 1988, see figure (1). the calculated t-value is greater than the tabulated t-value. for non-homogeneity removal, yevjevich (7) suggest fitting linear regression equations for both annual means and annual standard deviations, then applying the following equation: 22 , , avsd sj xjtxj tyj    ...(2) where: j, t= the annual and seasonal positions of the observations, respectively. y=transformed series(homogeneous) x = historical non-homogeneous series. av2,sd2= the average and standard deviation of the second sub –sample respectively, and xj,sj= linear regression equations for annual means and standard deviations against years. thus the data are divided into two subsamples, the first (12) years long (1977-1988) and the second (9) years long (1989-1997). the first sub-sample will be transformed according to the above equation. the two sub-samples were then tested again using t-test to check the homogeneity. the result of applying the above equation are shown in figure (2) and table (2) below, hence the rafa al-suhaili al-khwarizmi engineering journal, vol. 4, no. 2, pp 27-36 (2008) 29 data are homogeneous. since the calculated t-values is less than tabulated t-value. 3transformation to normally distributed data it is of common practice in timeseries analysis to transform the data to the normal distribution. this means, to remove the skewness in the data and try to make it nearly zero. for the normalization process several transformations may be used to normalize the data, but the most common one is the power transformation. the power transformation used in this research is the one suggested by box and cox (2) (see equation (3) below). the application of this transformation begins with the estimation of the transformation coefficient value (). this coefficient has a value between (-1) and (1) and is strongly related to the skewness coefficient (cs).table (3) shows values of cs computed for each transformed series, using different -values. the values above were found to best fitted by a second polynomial equation. =0.0249cs 2 +0.0132cs+0.01 …(3) in order to find the λ-value that will normalize the data, the skewness coefficient cs in the above equation is substituted by zero, which gives a λ value as 0.01. this value will be used to get the transformed series according to the box and cox transformation as follows:  )1(   x y …(4) where: y: the transformed series, x : the original series data. table (4) shows the monthly means and standard deviations for the original and transformed series. 4determination of the independent stochastic component the series obtained after the removal of nonhomogeneity and non-stationary (periodic component of mean and standard deviation) is termed as the dependent stochastic component of the process and denoted as (p,t ). the values of monthly mean and standard deviations were used to find the value of the independent stochastic component by the following equation: p,t= t ttpy  , …(5) where: p,t = is the dependent stochastic component. t =is the mean value of yp,t data at position p(month). t =is the standard deviation value of yp,t data at position p(month). the values of p,t may be fitted by a suitable model whose parameters will depend directly or indirectly on the amount of existing correlation represented by the lag rk serial correlation coefficient model (rk) ,figure (3 a). one of the most familiar models, are the autoregressive model. it is preferable to try the first degree model, and then check its adequacy to remove the dependency of the p,t series in the first degree model fails to remove the dependency, the second degree model will be used, and so on. the first degree autoregressive model required the calculation of lag-one (r1) serial correlation coefficient, which was found to be r1=0.664. the model is represented as the relation between the dependent stochastic component (p,t) and the independent stochastic component (p,t). the independent stochastic series (p,t) is a series of random numbers usually with zero mean and unit variance. as mentioned above one of the most used models is the first order autoregressive model (markov model). this model express the relationship between the p,t and  p,t as follows: p,t=a x p,t-1+ 21 a  p,t …(6) where: a= r1 substituting the value of a =(0.664) in the above equation the independent stochastic component  p,t, could be found using:  p,t =(p,t -0.664 x p,t-1)/0.747 ...(7) in order to test the validity of the proposed first order autoregressive model, the correlogram of the p,t component should be found and tested. this correlogram is shown below which show that the first order autoregressive model, is suitable since the values of the serial correlation coefficient are fluctuated around the zero-values. hence the proposed model was capable of removing the dependency between the values of p,t, figure (3 b). 5model verification: upon the completion of the first four steps above, the model parameters were found. as mentioned before the observed data series of tss was divided into two parts (1977-1997), was used for the analysis (i.e., models parameters rafa al-suhaili al-khwarizmi engineering journal, vol. 4, no. 2, pp 27-36 (2008) 30 estimation), the other part (1998-2000), will be used now for model verification. usually in practice, the model is used to generate future values (series). the model validity will be decided upon the comparison between the statistical properties of the generated series with those of the observed one that was not used in the estimation of the parameters of the model. the microsoft excel program was used for generating future series for the tss-values. three series were generated as shown in table (5). the generation process begins by generating a standardized normally distributed random series (i.e., with zero mean and unit variance) then, using those as p,t values to generate the p,t values using the first autoregressive model. the tss values were found using a reverse process of the analysis conducted in steps (2-4). table (6) shows the generated monthly tss values using the three generated randomized series, proposed to be for years 1998, 1999 and 2000. the observed tss concentrations for these 3-years are shown in table (7). figure (4) shows the values of mean monthly tss concentrations calculated from the generated series rand 1, rand 2, and rand 3 numbers as well as those calculated using the observed tss record for the period 1998 to 2000. table 8 shows the values of the mean, standard deviation and skewness coefficient of observed data and those of the observed one. table (9) shows the results of the t-test for monthly means of observed and generated tss series. conclusions 1) the series of monthly tss concentrations in euphrates river at al-nasria province is nonhomogeneous. the non-homogeneity can be attributed to the disposal of effluent wastewater from the constructed treatment plants. 2) the suitable value of the power transformation parameter  that can be used to transform data to the normal distribution was found to be 0.01. 3) the correlogram of the observed independent stochastic component indicate the capability of the first order autoregressive model to model to time-dependency of the dependant stochastic component. 4) the t-test result shows that the obtained model can presence future forecasted values for the monthly tss values. table 1 the missing data of the recorded monthly tss (mg/l) in a period from 1977 to 1983. year month 1977 1978 1979 1980 1981 1982 1983 jan. 1056 1417 972 1264 1738 1168 4187.7 feb.  1518 1204 1301 1728 1325 2011 march. 1145 1421 1222  1557 1650 1912 april.  1322 1209 1290 1578 1578  may. 1160  1248  1730 1730  june. 1416 1667 1584 1491 1545 1545 1511 july.  1273 1528  1194  1601 august. 1366 1412 1293 1658 1145 1600 1780 sep. 1429 1316 1834 1560 1375  1620 oct. 1447 1250 1301 1620 1228 1311 1555 nov. 1457  1633 1720 1253  1858 dec. 1573 1024 1169 1805 1233 1954 1340  missing data rafa al-suhaili al-khwarizmi engineering journal, vol. 4, no. 2, pp 27-36 (2008) 31 table 2 mean and standard deviation of each sub-samples before and after applying the procedure of removal of non-homogeneity. before removal after removal mean standard deviation mean standard deviation set 1 data 1699.60 427.47 2821.42 386.52 set 2 data 2821.41 386.50 2821.41 386.50 table 3 variation of skewness coefficient with box and cox transformations coefficient.  -0.8 -0.6 -0.4 -0.2 0.2 0.4 0.6 0.8 cs 0.005 0.016 0.005 0.039 -0.007 0.010 0.027 0.045 table 4 monthly means and standard deviations for the original homogeneous series and the normalized series in a period from 1977 to 1997. original homogeneous series (x) normalized series (y) mean standard deviation mean standard deviation january 2817.434 716.122 108.240 0.243 february 2896.002 726.797 108.263 0.284 march 2980.307 633.320 108.306 0.223 april 2913.758 778.573 108.268 0.286 may 3030.474 669.865 108.322 0.236 june 2722.360 449.878 108.216 0.176 july 2734.419 305.069 108.229 0.117 august 2929.858 426.885 108.300 0.150 september 2824.034 306.742 108.264 0.118 october 2678.520 374.626 108.203 0.140 november 2718.747 343.527 108.220 0.139 december 2611.145 562.362 108.163 0.222 table 5 values of generated randomized numbers (p,t) for 1998,1999 and 2000 years. rand 1 rand 2 rand 3 1998 1999 2000 1998 1999 2000 1998 1999 2000 jan. 0.271 0.359 0.465 0.850 0.150 0.815 0.210 0.041 0.363 feb. 0.313 0.476 0.559 0.075 0.987 0.184 0.132 0.724 0.944 mar. 0.188 0.490 0.866 0.844 0.801 0.140 0.218 0.955 0.855 apr. 0.980 0.807 0.849 0.105 0.848 0.974 0.670 0.173 0.363 may. 0.348 0.223 0.436 0.859 0.619 0.073 0.427 0.267 0.961 june 0.721 0.719 0.290 0.365 0.038 0.599 0.283 0.171 0.053 july. 0.594 0.060 0.727 0.426 0.997 0.727 0.383 0.262 0.953 aug. 0.388 0.274 0.301 0.475 0.497 0.537 0.824 0.101 0.176 sep. 0.273 0.277 0.640 0.799 0.893 0.667 0.453 0.278 0.047 oct. 0.073 0.130 0.390 0.943 0.929 0.094 0.382 0.731 0.266 nov. 0.295 0.520 0.634 0.295 0.932 0.087 0.568 0.208 0.770 dec. 0.964 0.650 0.629 0.654 0.783 0.698 0.126 0.471 0.981 rafa al-suhaili al-khwarizmi engineering journal, vol. 4, no. 2, pp 27-36 (2008) 32 table 6 generated monthly tss concentrations (mg/l) for years (1998, 1999, and 2000). tss conc. from rand 1 mean tss conc. from rand 2 mean tss conc. from rand 3 mean 1998 1999 2000 1998 1999 2000 1998 1999 2000 jan. 3318 3159 3419 3298 3184 3439 3664 3429 3524 3600 3822 3649 feb. 3915 3241 3630 3595 3599 3396 3716 3571 3751 3856 4254 3954 mar. 3563 3206 3407 3392 3355 3332 3818 3502 3713 3670 3670 3685 apr. 3939 3624 3810 3791 3717 3158 3735 3536 3644 4005 4029 3892 may. 3902 3565 3625 3697 4047 3625 4031 3901 3849 4132 4150 4044 june 3171 3304 3209 3228 3485 3040 3248 3257 3104 3503 3435 3347 july. 3025 3062 3016 3034 3117 3085 3098 3100 2936 3111 3261 3103 aug. 3392 3477 3361 3410 3547 3322 3308 3392 3121 3484 3727 3444 sep. 3185 3135 3113 3144 3220 3162 3080 3154 3034 3098 3459 3197 oct. 3116 2938 3058 3037 3018 3057 2911 2995 2960 3055 3441 3152 nov. 3096 2931 3192 3073 3187 2997 3031 3071 3064 3038 3340 3147 dec. 2977 3123 3062 3054 3272 3165 2992 3143 3168 3220 3290 3226 table 7 observed tss concentrations (mg/l) from period 1998 to 2000. 1998 1999 2000 january 4870 3535 4470 february 5326 3570 4530 march 5975 3535 3997 april 6094 3680 3608 may 5879 3710 3519 june 5530 3704 4800 july 4320 3620 3355 august 6530 3635 5370 september 5092 3540 3073 october 5928 4416 3376 november 6975 4514 2895 december 7148 4612 3690 table 8 overall properties of observed data and generated series. observed data rand 1 rand 2 rand 3 mean 4512 4425 4456 4654 standard deviation 422.69 356.93 353.59 460.03 skewness coefficient 0.6338 0.6915 0.4685 -0.1061 tables 9 results of the t-test for monthly tss means, t tabulated= 2.776. t rand 1 t rand 2 t rand 3 january 0.226 0.655 1.402 february 0.535 0.557 1.467 march 0.033 0.221 0.556 april 0.726 0.304 0.882 may 0.735 1.075 1.338 june 0.690 0.591 0.376 july 0.991 1.297 1.200 august 0.741 0.766 0.664 september 0.484 0.503 0.595 october 0.697 0.773 0.477 november 0.581 0.584 0.497 december 1.036 0.917 0.814 rafa al-suhaili al-khwarizmi engineering journal, vol. 4, no. 2, pp 27-36 (2008) 33 0 500 1000 1500 2000 2500 3000 3500 1977 1979 1981 1983 1985 1987 1989 1991 1993 1995 1997 years a n n u a l m e a n o f t s s c o n c . fig. 1. spilt sample test of the original historical data. 0 500 1000 1500 2000 2500 3000 3500 4000 1977 1979 1981 1983 1985 1987 1989 1991 1993 1995 1997 a n n u a l m e a n o f t s s c o n c e n tr a ti o n (m g /l ) years fig. 2. split-sample test for the historical data after non-homogeneity removal. set 1 mean= 1699 set 2 mean= 2821 year 1988 tcalculated = 6.17 ttabulated = 1.729 old set 1 data transformed set 1 data tcalculated= 0.01 ttabulated = 1.729 set 2 data rafa al-suhaili al-khwarizmi engineering journal, vol. 4, no. 2, pp 27-36 (2008) 34 -1 -0.75 -0.5 -0.25 0 0.25 0.5 0.75 1 0 5 10 15 20 25 30 lag k rk fig. 3. a: corrologram of the dependent stochastic component (p,t), rk is correlation coefficient, lag rk is the time of creeping of correlation coefficient values . fig. 3. b: corrologram of the independent stochastic component ( p,t) obtained using first order autoregressive model, rk is correlation coefficient, lag rk is the time of creeping of correlation coefficient values. 3000 3500 4000 4500 5000 5500 6000 a n n u a l m e a n o f t s s c o n c e n tr a ti o n (m g /l ) month mean r1 mean r2 mean r3 mean of obseved data fig. 4. comparison of observed mean monthly tss values, with those of the three generated series. limit= 0.15 limit= -0.15 -1 -0.75 -0.5 -0.25 0 0.25 0.5 0.75 1 0 5 10 15 20 25 30 lag rk rk limit= 0.15 limit = -0.15 lag rk rafa al-suhaili al-khwarizmi engineering journal, vol. 4, no. 2, pp 27-36 (2008) 35 references [1] al-suhaili r.h., (1985): “stochastic analysis of daily streamflow of tigris river", m.sc. thesis, college of engineering, university of baghdad. [2] box, g.e.p., and, jenkins, g.m., "time series analysis,forcasting and control". holdened day, san fransisco, 1976. p.575. [3] kadri yurkel and ahmet kurunc.,(2006)" performances of stochastic approaches in generating low streamflow data for drought analysis". journal of spatial hydrology vol. 5 no. 1. internet. [4] garry l. grabow, dan line, jean spooner and laura lombardo.," how to detect a water quality change using sas an example"pdf, internet. [5] howard s.peavy, donald r.rowe and georage techobanoglous., "environmental engineering", mcgrew-hill book co.,1986. [6] nemerow,n.l.,"scientific stream pollution analysis",mcgrew-hill book co.,1974. [7] yevjevich,w.,m.,"structural analysis of hydrology time series", hydrology paper no.56,fort collins, colorado, nov.,1972. [8] zhiyong hung and hiroshi morimoto, (2006)" water pollution models based on stochastic differential equations". department of earth and environmental sciences graduate school of environmental studies, nagoya university, pdf, internet. " ، .ٔصاسة انًٕاسد انًبئٍت ، قسى انًذنٕالث انًبئٍت [9] ،"انخحبنٍم انكًٍٍبٌٔت نُٓش انفشاث فً انُبصشٌت .حقبسٌش دٔسٌت rafa al-suhaili al-khwarizmi engineering journal, vol. 4, no. 2, pp 27-36 (2008) 36 تحليل البيانات الشهرية لتراكيز الوواد العالقة الكلية لنهر الفرات في هذينة الناصرية طارق جواد كاظن.م.م رافع هاشن السهيلي. د.أ صبيعت بغذاد/ كهٍت انُٓذست/ قسى انُٓذست انبٍئٍت الخالصة حى فً ْزا انبحذ ححهٍم انبٍبَبث انشٓشٌت نخشاكٍض انًٕاد انعبنقت انكهٍت نُٓش انفشاث فً يذٌُت انُبصشٌت، حٍذ حى اخز انًعذل نهشٓشي ( . 2000-1977)نهبٍبَبث انًخٕفشة يٍ سُت ببسخخذاو طشٌقت . 1988فً انبذاٌت حى اخخببس انبٍبَبث نًعشفت فًٍب ارا كبَج يخضبَست أ غٍشيخضبست ٔٔصذ آَب غٍش يخضبَست عُذ سُت yevichevichرى حى حٕصٌع انبٍبَبث طبٍعٍبًببسخخذاو طشٌقت انعبنًٍٍ . حى اصانت عذو انخضبَس فً انبٍبَبثbox ٔ cox . بعذ رنك حى اخز انقٍى انًعذنت الصانت انًشكبت انذٔسٌت عُٓب ٔرنك نهحصٕل عهى انذانت انًسخقهت انخً حى ًَزصخٓب بًٕدٌم يٍ َٕع سهسهت markovian . ( 2000-1998) حٍذ حشكج قٍى انخشاكٍض نهزالد سٍٍُ انًخبقٍت 1997-1977اٌ انخحهٍم اعالِ حى حطبٍقّ عهى انبٍبَبث يٍ سُت .السخخذايٓب فً انخحقق يٍ َخبئش انًٕدٌم ٔقذ بٍُج t-testٔيٍ خالل انًُٕرس انزي حى انخٕصم انٍّ حى حٕنٍذ قٍى نزالد سٍٍُ يسخقبهٍت نًقبسَخٓب يع انقٍى انًقبست ٔببسخخذاو اخخببس . انُخبئش ايكبٍَت االعخًبد عهى انًُٕرس العطبء َخبئش يسخقبهٍت يقبٕنت <4d6963726f736f667420576f7264202d20cde4ede420e6e3cde3cf20e6e4c8ede132342d203333> al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 16, no. 2, june, (2020) p. p. 2433 developing a prosthesis design using a gearbox to replicate the human hand mechanism haneen mahdi jaber* muhammed abdul-sattar** nabel kadhim abd al-sahib*** *,**department of mechanical engineering /college of engineering/ al-nahrain university ***department of medical engineering /college of engineering/al-nahrain university *email: hanen990990@gmail.com **email: m1976sjnr@gmail.com ***email: n-k-alsahib@yahoo.com (received 26 january 2020; accepted 26 april 2020) https://doi.org/10.22153/kej.2020.04.001 abstract prosthetic is an artificial tool that replaces a member of the human frame that is absent because of ailment, damage, or distortion. the current research activities in iraq draw interest to the upper limb discipline because of the growth in the number of amputees. thus, it becomes necessary to increase researches in this subject to help in reducing the struggling patients. this paper describes the design and development of a prosthesis for people able and wear them from persons who have amputation in the hands. this design is composed of a hand with five fingers moving by means of a gearbox ism mechanism. the design of this artificial hand has 5 degrees of freedom. this artificial hand works based on the principle of under actuated system. the used motor is 6v polulu high-power carbon brush micro metal gearmotor with gear ratio equal to 50:1. the motor was chosen due to its compactness and cheapness. the hand manufacturing process was done using a 3d printer and using polylactic acid material. numbers of experiments were accomplished using the designed hand for gripping objects. initially, the electromyography signal (emg) was recorded when the muscle contracted in one second, two seconds, three seconds. the synthetic hand was able to produce a range of gestures and grasping for objects. keywords: prosthesis, gearbox mechanism, pololu high, solid work, 3d printing. 1. introduction the personal hand is an integration of complicated systems of tendons, stress, muscles, and frame. behind a hand border, the capability of people to investigate and react to their ambiance. an unfortunate feature a compact manual ability, having difficulty with controlling and detecting objects. physical variations, among others, will result in psychological problems [1]. the human hand has 22 degrees of freedom [2], which are created by 27 unique bones and 30 muscles [3]. nearly thirty-five percent of the removed appendages are removed of arm or portion of the arm. until a long time back, the advancement of prosthetic hand that brings back the capacities and steadfastness. for individuals who have removal, the arrangement and improvement of any prosthesis depend on many-sided quality of the body portion being supplanted and rehabilitative necessities of the prosthesis client. upper appendage prostheses are set for those people who have either portion or entirety upper appendage nonattendance, which may either be obtained (through removal) or innate the prosthetic hand is as it were portion that can imitate the haneen mahdi jaber al-khwarizmi engineering journal, vol. 16, no. 2, p.p. 2433 (2020) 25 developments and capacities of the human hand in the day by day work. c. pylatiuk, explain a new experimental hand restorative design that differs from the typical prostheses. with the idea of addressing consumers’ necessities, practicality was increased, and the cosmetic look became close to the lost body part [4]. t.maeno developed a five-fingered hand having around a break even with several degrees of freedom toward the person's hand. the machine hand is decided in an interesting way utilizing ultrasonic engines and flexible parts [5]. e.tumas.wiste developed a new design to acquire a complete grasping taxonomy. it composed of eight required hand postures with the possibility of controlling them by emg signals. the design consisted of an thropomorphic hand having five fingers with 16 joints [6]. rocha, made several studies deal with the applied forces by the hand throughout the griped objects in process [7]. t.joseph.ms.bs.belter, studied the mechanical properties of the artificial industrial hands has been performed. a pilot study on the impact of many commercially available reproductive health labor, including vincent, ilimb, ilimb pulse, bebionic, bebionic v2, and michelangelo hands were reported. the design of the fingers and motility, the joint mechanical couple, and the operating methods of these artificial hands were commercially invested [8]. g.k.jones studied the stability of the mechanical design of the primary hand mechanism. also, it has appeared how the traditional circuit board fits within the palm, and a general idea of the modified manage framework is depicted, with potential future increases of amputee advice [9]. abd al-sahib n. kadhim and muhammad a.m., presented a methodology to design and manufacture an artificial hand for prosthetic application. the proposed design is a five-finger hand with the forearm actuated by an under-actuated system composed of tendons and servomotors. the manufacturing strategy started by design the model using the solidworks software and manufactured using the 3d printing technique. it possesses 15 dof, 3dof for each finger [10]. this paper study the kinematic motion and the method of design of a prosthesis with a gearbox mechanism with full function of movement. manufacturing of each part in the prosthetic hand and assembly it and then testing the hand for handling the objects were then conducted. the novelty of this paper include using the gearbox for the operating system and the mobility of the fingers , also includes the location of the dc motor in the palm of the hand. 2. methodology 2.1. geometry design this part explains the geometry design procedure used to design the mechanical function of the prosthetic hand. the design of the prosthetic hand is drawn using solidworks, since solidworks is introduced, it has been a great tool for every engineer who is interested in design. it is a complete computer-aided design (cad) package that offers modeling of complicated structure. the first part to design was the finger, which consists of two parts: the distal phalange and the proximal phalange. the link between wheel gear and phalanges(proximal and distal) was done by using a worm wheel;when 6v pololu motor is powered, the distal move up and linked with proximal phalange. the thumb is designed to do different functions from any other designed parts, and it is driven by two 6v polou motor, and it is capable for extension and flexion. the palm is divided into two regions; one supports each finger, and the location of motors is called (back palm). the second part of the palm is called (upper palm). these parts work in a similar manner to the human hand, as shown in figure (1). the forearm part is designed as a base to support the palm and the rest of amputation. the wrist is fixed and designed to join the forearm with palm.. all the designed parts are then assembled together in the solidworks environment to form the final shape of prosthetic hand,see the figuresbelow. fig. 1. distal finger. fig. 2. proximal finger. haneen mahdi jaber al-khwarizmi engineering journal, vol. 16, no. 2, p.p. 2433 (2020) 26 fig. 3. thumb motor design. fig. 4.thumb mount. fig. 5. wrist design. fig. 6. palm bottom design. fig. 7. palm up rigid design. fig. 8. complete prosthetic hand design. 2.2. finger kinematics in our kinematics model, the prosthetic finger comprises two connections relating to the two phalanges of the genuine finger. the finger is set with one active dof and one passive. the active dof is at the primary joint, and the other one is in the two joints combined with the first one. denavit-hartenberg (d-h) is generally utilized technique to take care of the forward kinematics issue, where the change in the arrangement is utilized to create an individual change demonstrating the heading and position of the fingertip as for palm. the finger kinematics can be considered in 2d kinematics lying in the x-y plane. the d-h theorem contains four parameters, haneen mahdi jaber al-khwarizmi engineering journal, vol. 16, no. 2, p.p. 2433 (2020) 27 which are: angle θ_i, the link/phalanx offset d_i, the link /phalanx length l_i, and the link/phalanx twist α_i. these four factors are utilized to figure the position and orientation of the fingertip. it is worth mentioning that the four fingers have the same range of rotation of joints but they differ in the dimensions of the phalanges (only the max length l_i). see the figures below for the parameter in the fingers. fig. 9. coordinate frames of finger. once the d-h outline framework has been set up for every link, a homogeneous transformation matrix will be without much of a stretch be produced recitation it coordinate casing the (i-1) coordinate casing [11]: ��=����,�.� ���, �.� ���,��.����,�� …(1) the equation equal � � 1��= ������ ����������� ���������� ������������ ����� ����������� �������0 ����� ����� ��0 0 0 1 � this equation …(2) d-h parameters for the fingers are shown in table (1),(2). table 1, d-h parameter for the finger link no. length li twist αi offset di angle θi 1 l1 0 0 θ1 2 l2 0 0 θ2 table 2, d-h parameter for the thumb link no. length li twist αi offset di angle θi 1 l1 �/2 0 θ1 2 l2 0 0 θ2 substituting the parameters in the above tables in equation 2and referring to cos as (c) and for sin as (s) ��� = � � �� = ��!� " ��# ��!� " ��# 0 � �� " $��!� " ��#�!� " ��# �!� " ��# 0 � �� " $��!� " ��#0 0 1 00 0 0 1 � this equation …(3) [%�,&�,'�] = orientation matrix of the it manage system traditional at connect i with deference to base coordinate edge. upper left 2*2 partitioned matrix of t_i . location of the vector pointing from origin of the base management system to the origin of the (�=i the coordinate system. upper 2*1 partitioned matrix of t_i. the solution for the position of the fingertip is found as given as : )�*�+,-./�0=� cos �1+�� cos!�1 " �2# …(4) )5*�+,-./�0=� sin �1+�� sin!�1 " �2# …(5) )�*�+,-./�0=0 …(6) ∅=�1+�2 … (7) 2.3. prosthetic hand manufacture the prosthetic hand was built using 3d printing as an active additive manufacturing, which is a method utilized to fabricate almost any computer-aided design (cad) model using thermoplastics materials, such as pla, abs, and pet. this method promises customization and simplicity with low-cost. the application of this method to fabricate parts suited to address local needs in developing countries has become of interest in recent years. the application of 3d printing in low-income countries, primarily using open-source designs, holds much promise for delivering a whole range of desired equipment on demand. the technology has been used to provide humanitarian aid to those in need [12]. each finger of the prosthetic hand is actuated by 6v polou motor with a gear ratio equal to 50:1 located at the palm. the proposed plan of the hand and the other parts of the hand were printed using the 3d printing technology. the printing procedure guarantees a high tall precision when it comes to dimension; i.e, there was not much contrast between the ultimate shape measurements and the cad plan. as proposed, each finger is composed of two of these parts, which were connected together and fastened by pins between distal and proximal phalange. figure (2) shows the finger in its final assembly. the palm on the haneen mahdi jaber al-khwarizmi engineering journal, vol. 16, no. 2, p.p. 2433 (2020) 28 other side is composed of two parts as planned. the fingers were attached to the palm in a simple, straightforward way; all parts are fitted together without noticeable clearance. figure (3) shows the final shape of the designed prosthetic hand. fig. 10. part of finger. fig. 11. palm with finger. fig. 12. fully prosthetic hand. 2.4. driving mechanism the gears system is composed of a worm that engaged with a gear wheel (the worm wheel), to produce the rotating motion will be moved between 2 beams at right angles to all other [13]. the worm-gear mechanism is illustrated in figure (13), the motor is put closer to the metatarsophalangeal (mcp) joint but requires the motor axis to be offsetted. the worm gear is mounted on the motor shaft to drive the gear that is mounted on the proximal phalangeal. turning the worm gear in one way or another will control the finger motion direction [14]. fig. 13.worm-gear finger mechanism . fig. 14. worm-gear with motor inside palm. 2.5. surface electromyography signal generation (emg) the emg signal is defined as a recording and evaluating the electrical signal generated by the muscle that is related to neuromuscular activation. it emerges from the stream of ions across the muscle fibers' membrane, which passes through the connective tissues to arrive at the detection electrode, located on the skin [15]. the term emg represent the electromyography: the electromyogram word contains three terms: haneen mahdi jaber al-khwarizmi engineering journal, vol. 16, no. 2, p.p. 2433 (2020) 29 electro, which implies touching on electrical activity; myo, that contains a greek root that means muscle; and gram, that stands for recording. emg is accomplished using an instrument called electromyography to make a record called electromyogram, that means the emg is an electrodiagnostic procedure in the medical application for recording and evaluating the electrical activity created by skeletal muscles. figure (15) summarizes the composition of (emg) signal. the signal that passes through muscle fibers coming through axon that induces muscle contraction or influences other neurons called action potential (ap). the motor unit action potential (muap) can be defined as the summation of electrical activity for all activated muscle fiber by an mu. in figure (15) the αa and αb are all alpha mus recruited, the summation of muscle fibers aps that activated by αa known as ʃmuapa and the summation of muscle fibers aps that activated by αb known as ʃmuapb. this adds the muaps to each other in case of increasing the needed force, as a result of this summation of ʃmuapa and ʃmuapb the semg signal will emerge [16]. fig. 15. emg signal generation. 3. result and discussion 3.1. kinematics motion the kinematics motion of the prosthetic hand means establishing the coordination of the fingertip with respect to the base frame and presenting the workspace and how the fingre will move. to describe the trajectory of motion of the finger tip statistical analysis for each point in the finger (x, y, and z) is used. figure (16) shows the 2d plot of the finger tip expressed in points for each part of the finger, and it represents the angle of the joint of the finger part to avoid overlapping. the motion in x, and y directions for the little finger was as x = 0.968, y = -1.63, for the ring finger as x = 0.692, y = -1.643, for the middle finger as x = 0.964, y = -2.09, for the index finger as x = 1.092, y= -1.993. fig. 16. 2d fingertip kinematic motion. in figure (17) the blue line represents the thumb, which it intersects with the other lines (fingers). this intersection represents the validity of the prosthetic hand to grasp the objects. the thumb does not intersect with the little finger while the human thumb can intersect with the little finger. this intersection of the finger and overlapping with the thumb to the anthropomorphism of human hand and express the hand design is capable of movement and gripping object. this is an advantage in prosthetic hand designed. fig. 17. 3d plot showing the intersection between thumb and finger. 3.2. prosthetic hand gripping object after gathering the handle of prosthetic hand primary parts, the proposed hand design is tested . haneen mahdi jaber al-khwarizmi engineering journal, vol. 16, no. 2, p.p. 2433 (2020) 30 for the grasping design test, the hand is tested to hold three objects utilizing emg as flag input. the prosthetic hand can effectively perform grasping the three objects. the three grasp designs are pinch, chuck, and fist. the prosthetic design was tested to gripping different objects, such as key, screwdriver, cart and cylindrical tray using emg sensor with arduino microcontroller and the signal generated from activities of muscles, see the figures below. (a) (b) (c ) (d) fig. 18. prosthetic hand gripping (a) key,(b)s crew driver,(c) card and (d) cylindrical tray. 3.3. the pressure effect the effect of the pressure applied by the hand on the objects has been studied from the pinch, chuck, and fist for the five fingers of the hands. for the pinch, the thumb and the index reaches the highest pressure with respect to the time, for the thumb it reaches (960 kg/cm 2 ) as for the index it reaches (975.484 kg/cm 2 ). as time increases, the pressure increases; after reaching a peak value, it starts to decrease. the effect on the thumb and index is the same at the chuck, enlarging the pressure into a peak value and the decreasing. for the fist, the pressure on th four fingers increases into a peak value with respect to the time and the decreases simultaneously, (956.42 kg/cm2) for the index, (942.285 kg/cm 2 ) for the ring, (876.564 kg/cm 2 ) for the middle, (875.725 kg/cm 2 ) for the pinky. figure (19, 20, 21) shows the effect of the pressure with respect to the time for the pinch, chuck, and fist, respectively. fig. 19. value of pressure sensor with pinch. haneen mahdi jaber al-khwarizmi engineering journal, vol. 16, no. 2, p.p. 2433 (2020) 31 fig. 20.value of pressure sensor with chuck. fig. 21. value of pressure sensor with fist. 4. conclusion the prosthetic hand presented in this work was factory-made via 3d printing strategies. the fingers unit was accomplished by polou 6v dc motor through a worm gear equipped with worm wheel close to the finger. the five fingers, wrist, and the attachment have five independent degrees of freedom. each finger is controlled by one motor while the thumb is controlled by 2 motors. the dc motor is mounted in palm. after collecting the signals for contracting the muscle for a period of one, two, and three seconds using emg, the motions (pinch, fist, jack chuck). the designed hand has successfully accomplished the test of different gripping samples. the worm gear mechanism and the dc motors selection were the right choice for controlling the fingers rotational motion. 5. references [1] s.micera, j.carpaneto, s. raspopovic,” control of hand prostheses using peripheral information” ieee reviews in biomedical engineering, vol. 3. no.1, pp.48-68, 2010. [2] s.-y. jung, s.-k. kang and i. moon, "design of biomimetic hand prosthesis with tendon driven five fingers," in 2nd biennial ieee/ras-embs international conference biomedical robotics and biomechatronics, scottsdale arizona usa, 2008. [3] h.-m. schmidt and u. lanz, surgicananatomy of the hand, thieme, 2003. haneen mahdi jaber al-khwarizmi engineering journal, vol. 16, no. 2, p.p. 2433 (2020) 32 [4] c. pylatiuk, s. mounier , a. kargov, s. schulz, g. bretthauer," progress in the development of a multifunctional hand prosthesis" , proceedings of the 26th annual international conference of the ieee embs san francisco, ca, usa , september 1-5, 2004. [5] i. y. t. maeno, "five-fingered robot hand using ultrasonic motors and elastic elements", proceedings of the 2005 ieee international conference on robotics and automation barcelona, spain, april (2005). [6] e. tuomas. wiste, a. s. dalley, j. thomas. withrow and m. goldfarb, "design of a multifunctional anthropomorphic prosthetic hand with extrinsic actuation," in ieee international conference on rehabilitation robotics, japan, 2009. [7] d. n. rocha, c. de moraes, et.al," grip force analysis in a 3d hand prosthesis model", brazilian congress of mechanical engineering, brazil, 2011. [8] t. joseph. ms. bs. belter, l. jacob . et.al, "mechanical design and performance specifications of anthropomorphic prosthetic hands ", jrrd, vol.50, no.5, pp. 599–618, 2013. [9] g.k .jones, r. stopforth, "mechanical design and development of the touch hand ii prosthetic hand" r&d journal of the south african institution of mechanical engineering, pp. 23–34, 2016. [10] abd al-sahib n. kadhim, a. m. muhammed, and h. s. falah, "design and manufacture a 3d printed artificial hand",american journal of engineering research (ajer), no. 2, pp. 156–164, 2018. [11] r. ozawa, h. kobayashi and k. hashirii, "analysis, classification, and design of tendon-driven mechanisms", ieee transactions on robotics, 2014, vol. 30, no. 2, pp. 369-400. [12] micheal king, brienna phillips, marc shively, venkatch raman, aaron fleishman, sarah ritter and khanjan mehta, "optimization of prosthetic hand manufacturing", proceeding in ieee 2015 global humanitarian technology conference, usa, 2015.pp.59-61. [13] collins english dictionary – complete and unabridged, 12th edition 2014 , harpercollins publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014/ https://www.thefreedictionary.com/worm+ge ar. [14] g.k. jones and r. stopforth," mechatronic design and optimisation of a low-cost prosthetic hand ", msc thesis submitted university of kwazulu-natal,2015. [15] s. m. roberts,”investigation into the control of an upper-limb myoelectric prosthesis”,university of plymouth, 2002. [16] r. m. howard, “investigation of pattern recognition system based on emg signals for optimal electrodes number and positions” boletin epidemiologico semanal, vol.10, no. 12, pp. 121–124, 2002. ي ���� �� )2020( 2433، "! � 2ا�� د، 16 ��� ا���ارز�� ا��� ��� ا����� ��� 33 ام ,�%� +�وس �)'�ار آ��� ا�� ا�%$�#�� +.�#� +1��2 ا�.�ف ا/".��,� ���) ي ����� *���� � � ** ا�3)�ر ,%� � *** 8%�7 �6ظ1 ,% ا�4��2 **،* /�� � � �� �� ا ��������� ا �����/ ��� ا ����� ا��� ���*** � ��! ��/ ا ����� ����/ ھ���� ا #" ا��� ����� ا :� hanen990990@gmail.com*ا (��� ا) '�و *���) m1976sjnr@gmail.com :ا) '�و � ا *���) alsahib@yahoo.com-k-n :ا) '�و � ا �"9� ا� ��22 +#��*��إھ� أداة ا #�ف ا,+#��*� �! �!d ;=* e� ا,ط�ر ا (�4ي a�@" ?�(" ا ��ض أو ا =�ر أو ا '4;�:. 78ب ا5 224#� ا (!�22�3 ا e! �� �� ا =�وري ز��دة ا (!;ث d� ھ7ا ا �;g;ع j)k� ، � �' ��;ي ?�(" �; *�د ا �(';ر��. و?� ��اق ا) '(�ه إ l ا =(�ط ا #�ف ا ��*�ة 22d� ا !d �22� ا ; ��� ��7 22d �22'? ����22� ا �k e)� .���22��� و #;�� ط�ف +��*� tuv�ص ا r�در�� *�l ار �ا@: �� ا (!q اpk ھ�7ن. �� ا ��lg ا ��722 اtu5�ص ا l�* *�� �!';ي�ا)+#� �� �] \��� أ+�?] '!�ك *� ط��y آ �� *�(� ا '�وس. k��� ھ7ه ا �� �� ���k' ��e22 ھ722ه �٥' ;ن ھ7ا ا .�22��! در��ت ��22 ا ���a22+ �22ة ذات *� ��22 ا #��b! polulu �22 ا 'e�a4. ا �!�ك ا ��'�tم ھ; �*�� *�l أ��س `�م ا �� ا)+#���� �22(� �22وس �22�وي ا)��22�ن �22وس [22� . �22 إ 228�ز *�22د �pla �22. � ا\'��ر ا �!�ك ?�(" +8h �a�: ور\b� .:k *���� ا '��k] ا ��وي ?��'�tام ط�?�� ��fgf ا5?�22�د وا��t'22ام �22�دة ١: ٥٠ e22=� ���ك ا�u5�ء. d� ا (�ا�� ، e�822� �22 إ22u�رة i�22#t ���?��22 ا, ���k� ��22 وا�22hة ، (emg) ا '8�رب ?��'�tام ا �� ا�f �22d ��22=� �22�� ا �b224 ا�* �� ا,���ءات وا,���ك ?��u5�ء �*;�8� �'�� ، gfث f;ان. �� b ا �� ا)+#��*�� ��درة *�l إ '�ج �f. dr. shereen f. abd-alkarim /al-khwarizmi engineering journal, vol.3, no.2, pp 8 -16(2007) ٨ application of fuzzy logic in servo motor dr. shereen f. abd-alkarim dept. of education technology university of technology (received 31 julay 2006; accepted 24 april 2007) abstract: in this work the design and application of a fuzzy logic controller to dc-servomotor is investigated. the proposed strategy is intended to improve the performance of the original control system by use of a fuzzy logic controller (flc) as the motor load changes. computer simulation demonstrates that flc is effective in position control of a dc-servomotor comparing with conventional one. keywords: fuzzy logic, servomotor, controller introduction: when attempting to carry out the control of a system applying the classical control theory, we need the mathematical model of the process and information about the evolution of the system variables to close the control loops. normally both conditions are difficult to resolve: sometimes because of the complexity of the process or lack of knowledge we have about it, and other times because of the insufficient technological level reached at the moment in the sensor field. new process control techniques now combine advances in computer hardware and sensors with new programming techniques. in this way they attempt to solve difficult control problems [1]. fuzzy set theory, first formulated by zadeh nearly 30 years ago, constitutes the fundamentals of fuzzy logic which has emerged as an outgrowth of fuzzy set theory and a generalization of the infinite-value logic can be considered as a mathematical theory combing multivalued logic, probability theory, and artificial intelligence. it simulates the human approach in the solution of various problems by using an approximate reasoning to relate different data sets and to make decisions. since its introduction, fuzzy logic has gone through an important theoretical development and there has been a florescence of applications of this mathematical framework to a variety of fields [2]. in control systems, fuzzy logic is considered as an alternative for conventional control theory in the control of complex nonlinear plants where precise mathematical modeling is difficult or impossible [3]. the dc-servomotor is one the most widely used prime movers in industry today. generally speaking, dc-servomotor systems can be regarded as a simple low-order (second or third order) system without particular design or implementation difficulties. however, load effects have an obstructive influence on system response. as the load is al-khwarizmi engineering journal al-khwarizmi engineering journal, vol.3, no.2, pp8 -16 (2007) this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. shereen f. abd-alkarim /al-khwarizmi engineering journal, vol.3, no.2, pp 8 -16(2007) ٩ changed, the original controller generally cannot maintain the design performance and thus should be redesigned for the new system conditions. many types of control schemes, such as pi, pid, optimal, adaptive and robust controllers have been developed to reduce load effects. although each approach has its advantages and disadvantages in practical realization, most controllers still have to be designed on the basis of the parameters and the detailed structure of the plant. failing this, better control performance will not be obtained as load effects occur. therefore, this work develops a control structure to eliminate heavy and / or unbalanced load effects. the main advantage of fuzzy logic as compared to conventional control approach resides in the fact that no mathematical modeling is required for the design of the controller. the control rules are based essentially on the knowledge of the system behavior and the experience of the control engineer. since the fuzzy logic controller requires less complex mathematical operations than classical controllers, its implementation does not require very highspeed processors [4]. dc-servomotor control is a suitable application area for fuzzy control [5-9], primarily since the nonlinearities of the motor have a significant influence on process dynamics as the motor load changes. successful applications have been reported in a number of papers using fuzzy control as such or in conjunction with classical controllers [6-11] and that fuzzy controller is more robust to plant parameter value changes than a classical control algorithm and has better noise rejection capabilities . flc is especially suitable for compensating statical, nonvarying nonlinearities. this work first presents the fuzzy logic principles, basic concepts and design procedures of flc. next, following these design procedures, we evaluate the proposed fuzzy logic control system by simulation in order to check whether the responses of the designed systems acquire the desired performance. fuzzy logic principles: fuzzy logic (fl) has the following general observation [12]:  fl conceptually easy to understand.  the mathematical concepts behind fuzzy reasoning are simple and flexible.  with any given system, it's easy to message it or layer more functionality on top of it without starting again from scratch.  fl is tolerant of imprecise data. everything is imprecise if you look closely enough, but more than that, most things are imprecise even on careful inspection. fuzzy reasoning builds this understanding into the process rather than tacking it onto the end.  fl can be built on top of the experience of experts. in direct contrast to neural networks, which take training data and generate opaque, impenetrable modeis, fl lets you rely on the experience of people who already understand your system.  fl is based on natural language. the basis for fuzzy logic is the basis for human communication. fuzzy logic controller: the basic flc structure is shown in fig (1), where flc is used a supplementary role to enchance the existing control system when the control conditions change. it consists of four principle units [13]. these are the fuzzifacation, knowledge base, decisionmaking (computation) and defuzzification units. since data manipulation in an flc is based on fuzzy set theory, a fuzzification process is required to convert the measured "crisp" inputs to "fuzzy" values. the fuzzification unit first maps the measured values of input variables into corresponding universes of discourse u. the u is quantified and normalized to [ -1, +1 ]. it then converts the mapped input data into fuzzy sets based this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. shereen f. abd-alkarim /al-khwarizmi engineering journal, vol.3, no.2, pp 8 -16(2007) ١٠ upon fuzzy values, such as positive large (pl), negative small (ns) etc. we utilize the triangle-shaped membership function with seven term as shown in fig (2). the knowledge base contains a set of rules which construct the decision-making logic rule table tabulated in table (1) where 49 rules are used. the rule in column 1 ( e=nl ) and row 1 ( de=nl ) marked nl presents: if (e) is negative large (nl) and (de) is negative large (nl) then control input (ci) is negative large (nl) . where "and" operation is realized by "min" operation, i.e., uci = min {ue , ude }. other rules can be interpreted in the same way. the output of the decision –making logic is a fuzzy set. however, a deterministic value is generally required as the input to the process. that is, an interface unit between the process and the decisionmaking unit is necessary. several procedures have been proposed for the defuzzification task. however, in this work we use a centre of area method. it generally gives a better steady state performance than with other methods [14]. the crisp output is obtained using the following formula: ))(()))((( 11    n i i n i iicrisp vvvci  where n : is the number of support values of the fuzzy set. iv : is a support value.  : is the membership degree of iv mathematical model of the dcservomotor: for armaturecontrolled servomotors (220v, 3kw), the closed loop transfer function can be written as [5]: ))(()( 2 tatba t ksbrkkjsrksh  where: ra : resistance of armature of motor. kt : torque constant of motor. kb : back e.m.f. constant of motor. jm : inertia of motor rotor. jl : inertia of additional inertia disc. bm : viscous friction coefficient of motor shaft. bl : viscous friction coefficient of load shaft. j=jmjl b=bmbl in order to calculate the discrete transfer function gp(z), the sampling period t is chosen as 10 ms. then, the discrete time process is given by:     9491.08432.1 001932.0001941.0 9026.4 1531.20 )( 22                zz z s zzg s e ts p pi controller design: the pi controller is the most widely used controller in industry today. the analog version of a pi controller is:  t ippi dektektu 0 )()()(  where: )()()( tytrte  , )(tu pi is the pi controller output. the discrete-time implementation of the integrator is:     )1()1()( 2 )( kekeke t ke hence the associated discrete controller is :  )()()( kekkekku ippi this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. shereen f. abd-alkarim /al-khwarizmi engineering journal, vol.3, no.2, pp 8 -16(2007) ١١ and its transfer function is:        1 1 2 )( z zt kkzd ip from the previous equations, the final values for the pi controller gains can determined as follows: 110  ip kk for t = 0.01s simulation results: the fuzzy logic based control system has been studied by simulation in order to validate the design and to evaluate the performance. the parameters of the dc servo-motor used are: servo-motor : 220v , 3kw , ra=1.2ω , kt=2.1*10-3nm/a kb=85*103v/rad/s, jm=15*10-6 kgm2, jl=124*10-6 kgm2 , bm=12*10-6 nms , bl=45*10-6 nms . the response of the system using fuzzy logic controller obtained by simulation is shown in figs (3,4) for different cases for step input (with and without load). in this simulation, we compare results gotten by a fuzzy logic and pi controller which give good performance in a no load case as shown in fig (3). however, from fig (4) , as loading is connected to the servomotor, the flc results are obviously superior to the original pi control system. when the frictional load and/or the inertia disc load are included, the performance of the pi controller is not within the desired range and the pi controller must be adjusted. however, the redesign of the pi controller is very complex and troublesome. one need only design the flc to provide control command rather than redesign the pi. it is seen that flc provides faster response and less overshoot than pi controller. conclusion: a fuzzy logic based controller for a dcservomotor has been studied. the results have been compared to the conventional controller. the design of the fuzzy logic controller has been explained and the performance was evaluated by simulation. the simulation results indicate that flc provides the best performance in comparison with pi controller, and the shape of the flc surface is smoother than that of pi controller. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. shereen f. abd-alkarim /al-khwarizmi engineering journal, vol.3, no.2, pp 8 -16(2007) ١٢ fig.(1) basic structure of fuzzy logic controller. fig.(2) the membership function of e, de and ci in normalized scale. -1 -0.6 -0.3 -0.1 0 0.1 0.3 0.6 1 nl nm ns zr ps pm pl 1 (b) ci flc knowledge base fuzzification computation (decision – making rule) defuzzification servo motor fuzzy output fuzzy input reference signal r + e y angular position y -1 -0.5 -0.2 0 0.2 0.5 1 nl nm ns zr ps pm pl 1 (a) e and de this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. shereen f. abd-alkarim /al-khwarizmi engineering journal, vol.3, no.2, pp 8 -16(2007) ١٣ table (1) the control rules table of the flc. fig(3)the system response under no load case plpmpszrnsnmnle de zrnsnsnmnl nl nlnl pszrnsnsnmnlnlnm pmpszrnsnsnmnlns pmpmpszrnsnmnmzr plpmpspszrnsnmps plplpmpspszrnspm plplplpm ps pszr pl this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. shereen f. abd-alkarim /al-khwarizmi engineering journal, vol.3, no.2, pp 8 -16(2007) ١٤ fig (4) the system response under fractional load case this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. shereen f. abd-alkarim /al-khwarizmi engineering journal, vol.3, no.2, pp 8 -16(2007) ١٥ references: 1. warwick k. "control system", prentice-hall, 1989. 2. maiers j. and sherif y.s. "applications of fuzzy set theory", computer design, march 1991. 3. williams t. "fuzzy logic simplifies complex control problems", computer design, march 1991. 4. nasser t. and others "design and applications of fuzzy logic for the speed control of a direct-drive dc motor", 4th international conference, cattaee, amman-jordan 2002. 5.lim c. hzyama t. "experimental implentation of a fuzzy logic control scheme for a servomotor" , mechatronics 1993. 6.kung y. liaw c. "a fuzzy controller improving a linear model following controller for motor drives",ieee transaction on fuzzy systems 1994. 7.sclarence w.shimsjon b. "experiments with an intelligent servomotor system intelligent control systems" asme 1992. 8.shieh my. li t-hs."integrated fuzzy logic controller design",proceedings of ieee iecon 93. maui, hw 1993. 9.shieh my. li t-hs."implementation of integrated fuzzy logic controller".proceedings of fuzzieee/ifes 95.yokohama,japan 1995. 10. tan s. he sz.xu fl."fuzzy selftuning of did controllers", fuzzy sets and systems 1993. 11. zhao zy, tomizuka m.isaka s."fuzzy gain scheduling of pid controllers"proceedings of the ieee. conference on control applications. dayton,ohio 1992. 12. jamshidi m. and others "application of fuzzy logic towards high machine intelligence guotient system" ,prentice hall ptr ,1997. 13. lee c. "fuzzy logic in control systems",fuzzy logic controller, part ii . ieee trans. on systems, man. and cybernetics 1990. 14. pham d.t. and liu x."neural network for identification prediction and control", springer-verlag berlin heidelberg new york, 1997. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. shereen f. abd-alkarim /al-khwarizmi engineering journal, vol.3, no.2, pp 8 -16(2007) ١٦ للمحرك المؤازر تطبیقات المنطق الغامض شیرین فائق عبد الكریم. د فرع الكھرباء/ قسم التعلیم التكنولوجي الجامعة التكنولوجیة :الخالصة حیث درست خصائص اداء المحرك تصمیم المسیطرالغامض للمحرك الـمؤازر تم في ھذا البحث وقد اثبتت نتائج المحاكاة بان المسیطر الغامض للمحرك ذو فعالیة جیدة للسیطرة . باستخدام المحاكاة .الموقعیة للمحرك عند احمال متغیرة مقارنة بالمسیطر التقلیدي this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 4, no. 2, pp 5968 (2008) investigation of load and pressure distribution on wing with wake rollup for low speed aircraft laith w. ismail department of materials engineering/ university of technology (received 8 april 2008; accepted 22 julay 2008) abstract the presented work shows a preliminary analytic method for estimation of load and pressure distributions on low speed wings with flow separation and wake rollup phenomena’s. a higher order vortex panel method is coupled with the numerical lifting line theory by means of iterative procedure including models of separation and wake rollup. the computer programs are written in fortran which are stable and efficient. the capability of the present method is investigated through a number of test cases with different types of wing sections (naca 0012 and ga(w)-1) for different aspect ratios and angles of attack, the results include the lift and drag curves, lift and pressure distributions along the wing span taking into the consideration the effect of the angles of attack and the aspect ratios on the wake rollup. the pressure distribution on the wings shows that there is a region of constant pressure on the upper surface of the wings near the trailing edge in the middle of the wing, also there is a region of flow separation on the upper surface of the wings. a good agreement is found between the presented work results and other from previous researches. these results show that the presented method is able to capture much of flow over wings feature like separation and wake rollup. introduction in order to predict the aerodynamic forces of wings up to and beyond stall, including flow separation and wake rollup must be taken into account. prandtl l. and tietjens o. g [1] defined separation of flow first in 1904; fluid particles near the solid surface are retarded by the friction force and by the adverse pressure gradient in the free stream. if the momentum is insufficient, the particles will be brought to rest at the separation point. downstream of the point, the adverse pressure forces will cause reverse flow. the original boundary layer either passes over the region of recirculation fluid and re-attaches to the surface or forms a wake. in the case of finite wings, the wake is a form of vortex sheet leaves the wing. as a consequence of the pressure difference between lower and upper sides of the wing, a certain flow is caused around the lateral edges. thus starting a pair of strong trailing vortices. the vortex sheet immediately begins to roll itself up into these vortices; and if eventually passes all of its vortices into a pair [2]. several methods have been developed for wing problems taking into account the interaction between the several regions of flow around the wing. the present work is a combination of a higher order vortex panel method coupled with the numerical lifting line theory by means of iterative procedure including a model of separation and a model of wake rollup. many studies, both theoretical and experimental have been done, affected the development of the present method. jacob k. [3] used two-dimensional procedure combined with a lifting surface theory for the computation of the flow around wings with rear separation. the separation point was predicted by a boundary layer calculation for the attached part of flow. good predictions for the lift were obtained and it was shown that the wake flow behavior strongly influences the drag. cebeci t., lark r.w., chang k.c., halsey n.d. and lee k. [4] developed an interactive viscous-inviscid procedure for the laith w. ismail al-khwarizmi engineering journal, vol. 4, no. 2, pp 59-68 (2008) 60 computation of viscous flow over threedimensional wing with separation. pressure distributions over a number of spanwise stations, and the lift curve of the complete wing were computed. nilay [5] applied a new hybrid cfd/discrete vortex (cfd/vd) method in order to preserve vortices over long distances. this method couples lifting-line/free-wake method and research in the tip vortex and the wake of a fixed wing, the indication that the tip vortex shed from the wing tip is preserved over long distance when the hybrid cfd/dv method is applied, as a starting point before attempting to simulate rigid rotor flow field. theory 1. potential flow a higher order vortex panel method is developed from the source-vortex panel method [6] and reformulated in a manner suitable for the present model. for potential flow, the navierstokes equations are reduced to the euler’s equation of motion: pvv t v     1 ).( … (1) where 0.  v (equation of continuity). the total potential of the flow field may be written as: v   …(2) where  is the potential due to the uniform onset flow, and v the perturbation velocity potential due to the boundary surfaces. from eq. (2), the potential at arbitrary point (p) is:      n j jpanel jp j ppp ds s yxv 1 2 )( )sincos(     … (3) the vorticity at any point along the panel is given by: )()( 1 jj j j jj l s s    … (4) the velocity components u and v in x and y directions respectively at the control point of the thi panel due to the vortex distribution on the thj panel are calculated from [7]:               n j v p pipipi n j v p pipipi ij ij vv y vyxv uv x uyxu 1 1 sin),( cos),(     …(5) the surface velocity may be directly obtained from: niforv ii ,...,1  the pressure is calculated from the velocities according to bernoulli equation as shown below: nifor v v c i pi ,...,11 2         …(6) where    q pp cp 2. boundary layer the laminar separation criterion by curle and skan [8] is used, when the pressure gradient parameter is: 09.0 2 2  ds dv v e  …(7) the location of natural transition is obtained using michel’s method [9] when: 46.0 2 re re 22400 1174.1re s s tr        …(8) 3. wake shape iteration the iteration loop for wake shape is the inner loop and involves the potential flow analysis; within this loop the separation point is fixed. a local free vortex sheet panel correction angle is computed from the following equations: sheetvortexfreelowerfor nv sheetvortexfreeupperfor nv i ii i sep ii i                         . sin . sin 1 1 …(9) 4. rolling up of the trailing vortex sheet the wake behind lifting wings tends to follow the local velocity so that the wake will carry no loads. the vortices shed into the wake flow will eventually rollup near the wing tips to form single vortex patterns and tip vortices [5]. the trailing vortex sheet strength is equal to: dz d z  )( …(10) the circulation or the strength of the thi vortex located at ),( ii yz is:        m b z m b z m b z m b z i ii dz dz d dzg 2 2 2 2  …(11) laith w. ismail al-khwarizmi engineering journal, vol. 4, no. 2, pp 59-68 (2008) 61 where iz is the initial abscissa of the point vortex and 0iy at the same time. the lift and induced drag coefficients are obtained from:       2/ 2/ 2/ 2/ sin)( 2 )( 2 b b id b b l dzz av c dzz av c  …(12) the induced velocity iw of the thi vortex, induced by the thj vortex at ),( ij yz is: r g w j i 2  …(13) where 22 )()( jiji yyzzr  the components of iw are: i ji ii i ji ii w r zz wu w r yy wu       cos sin …(14) adding the contributions from all vortices other than the thi vortex itself and replacing u by dt dz and v by dt dy then:           m ij jiji jiji m ij jiji jiji yyzz zzg dt dy yyzz yyg dt dz 22 22 )()(2 )()(2   …(15) eq. (15) form a system of two simultaneous 1 st order ordinary differential equation: ),( ),( 2 1 yzf dt dy yzf dt dz   …(16) the solution can be obtained using the 4 th order rung-kutta method [10] and the location of each discrete vortex in the vortex sheet can be calculated. the new location of all vortices will represent the shape of the trailing vortex sheet behind the wing. results and discussion the capability of the present method for the estimation of load and pressure distributions on rectangular wings with wake rollup will be investigated in a number of test cases. these cases, with different types of wing sections (naca 0012 and ga(w)-1). fig. (1) illustrate the effect of aspect ratio on the lift curve, (a) for wing section naca 0012, (b) for wing section ga(w)-1. it is found that the increase of lift curve slop with increasing aspect ratio. the stall for naca 0012 occurs at about ( .deg18 ) for (ar=5), while for ga(w)-1 beginning at ( .deg20 ) for (ar=5). fig. (2) illustrate the effect of aspect ratio on the drag polar, it is shown that the drag coefficient increases rapidly as the lift coefficient increased and the drag coefficient is inversely proportional to aspect ratio. a good agreement was found between the presented work data and others from [11] shown in fig. (3). figs. (4) and (5) shows the local lift coefficient cl with reference to the total lift coefficient cl along the span. when the aspect ratio increases the lift distribution approaches more and more like rectangular distribution, for small aspect ratio the lift distribution is elliptic. figs. (6) and (7) shows three-dimensional pressure distribution on the upper surface of the span for different aspect ratios. for all cases, the buildup in pressure near the leading edge towards the middle of the wing is shown. the suction on the upper surface is increase with increasing aspect ratio. also, there is a region of constant pressure on the upper surfaces of the wings near the trailing edge in the middle of the wings. this indicates that there is a flow separation at these regions and this phenomenon is expected at high angles of attack. fig. (8) illustrate the rolled-up wake sheet for rectangular wing with naca 0012 airfoil compared at the same conditions from [12]. it is found that the spiral motion is observed on the wake element over the tip region during the rollup process, while the wake sheet remains relatively flat at the middle of the wing. a good agreement was found between the presented work results and others from [12]. fig. (9) illustrate a comparison between the present method results for rectangular wing with naca 0012 and others for [13] for the effects of angle of attack and aspect ratio shown in (a) and (b) on the rolled-up wake geometry. it is shown that the wake deformation is more pronounced at higher angle of attack and aspect ratio. a good agreement was found at this comparison. laith w. ismail al-khwarizmi engineering journal, vol. 4, no. 2, pp 59-68 (2008) 62 conclusions 1. the lift coefficient is predicted well by present method. the lift curve slope, the smooth variation with angle of attack is all good predicted. 2. the drag coefficient increases rapidly as the lift coefficient increased and the drag coefficient is inversely proportional to aspect ratio. 3. at low aspect ratio the stall occurs at higher angles of attack. separation begins at the station of maximum local lift in the middle of the wings. 4. finally, the developed method can be used successfully as a preliminary analysis tool for estimation of load and pressure distributions on low speed wings with wake rollup. nomenclature ar aspect ratio a wing area m 2 cd wing drag coefficient cl wing lift coefficient cl airfoil lift coefficient cp pressure coefficient gi strength of i th vortex m 3 /s.m l length of a panel m n number of surface panels n unit normal vector p pressure n/m 2 q dynamic pressure n/m 2 sre reynolds number at surface distance tr2re reynolds number at momentum thickness s surface distance (distance along the panel) m t time sec. u velocity component in xdirection m/s v velocity m/s ve velocity at the edge of the boundary layer m/s v total velocity vector m/s v velocity component in ydirection m/s x chordwise coordinate m y normal coordinate m z spanwise coordinate m  angle of attack deg. g geometric angle of attack deg.  circulation m 2 /s  vorticity strength m 3 /s.m sep vorticity strength at separation point m 3 /s.m 2 momentum thickness m  inclination of panel with xdirection deg.  pressure gradient parameter  density kg/m 3  velocity potential m 2 /s 0 2 4 6 8 10 12 14 16 18 20 22 angle of attack (deg.) -0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 w in g l if t c o e ff ic ie n t ar=5 ar=4 ar=3 2 4 6 8 10 12 14 16 18 20 22 angle of attack (deg.) 0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 w in g l if t c o e ff ii c ie n t ar=5 ar=4 ar=3 (a) (b) fig. 1. aspect ratio effect on the lift coefficient wing section naca 0012 (b) wing section ga(w)-1 laith w. ismail al-khwarizmi engineering journal, vol. 4, no. 2, pp 59-68 (2008) 63 0.00 0.04 0.08 0.12 0.16 0.20 0.24 0.28 wing drag coefficient 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 w in g l if t c o e ff ic ie n t ar=5 ar=4 ar=3 -0.02 0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18 wing drag coefficient -0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 w in g l if t c o e ff ic ie n t ar=5 ar=4 ar=3 (a) (b) fig. 2. aspect ratio effect on the drag polar (a) wing section naca 0012 (b) wing section ga(w)-1 (a) (b) fig. 3. (a) aspect ratio effect on lift coefficient for rectangular wing (b) aspect ratio effect on drag polar for rectangular wing [11] laith w. ismail al-khwarizmi engineering journal, vol. 4, no. 2, pp 59-68 (2008) 64 (a) (b) fig. 4. spanwise lift distribution on a rectangular wing section naca 0012 (a) .deg6g (b) .deg12g (a) (b) fig. 5. spanwise lift distribution on a rectangular wing section ga(w)-1 (a) .deg6g (b) .deg12g -1.00 -0.80 -0.60 -0.40 -0.20 0.00 0.20 0.40 0.60 0.80 1.00 1.20 2z/b -0.4 -0.3 -0.2 -0.1 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 ar=5 ar=4 ar=3 l l c c -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 2z/b -0.8 -0.7 -0.6 -0.5 -0.4 -0.3 -0.2 -0.1 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 ar=5 ar=4 ar=3 l l c c -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 2z/b -0.90 -0.60 -0.30 0.00 0.30 0.60 0.90 1.20 1.50 ar=5 ar=4 ar=3 l l c c -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 2z/b -2.5 -2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0 ar=5 ar=4 ar=3 l l c c laith w. ismail al-khwarizmi engineering journal, vol. 4, no. 2, pp 59-68 (2008) 65 (a) (b) fig. 6. pressure distribution on the upper surface of wing with naca 0012 (a) ar=3 (b) ar=4. (a) (b) fig. 7. pressure distribution on the upper surface of wing with ga(w)-1 (a) ar=3 (b) ar=4. laith w. ismail al-khwarizmi engineering journal, vol. 4, no. 2, pp 59-68 (2008) 66 0.0 0.2 0.4 0.6 0.8 1.0 1.2 2z/b -0.2 -0.1 0.0 0.1 0.2 2 y /b [12] presented work fig. 8. rolling up tip vortices of a rectangular wing with naca 0012 for ar=8 and .deg5 fig. 9. angle of attack and aspect ratio effect on the wake section for rectangular wing naca 0012 (a) ar=8 and .deg10 (b) ar=6 and .deg6 0.0 0.2 0.4 0.6 0.8 1.0 1.2 2z/b -0.4 -0.2 0.0 0.2 0.4 2 y /b [13] presented work (a) 0.0 0.2 0.4 0.6 0.8 1.0 1.2 2z/b -0.4 -0.2 0.0 0.2 0.4 2 y /b [13] presented work (b) laith w. ismail al-khwarizmi engineering journal, vol. 4, no. 2, pp 59-68 (2008) 67 references [1] prandtl l. and tietjens o. g. “fundamentals of hydroand aerodynamics”, dover 216. [2] sighard f. hoerner “fluid – dynamic lift”, practical information on aerodynamic and hydrodynamic lift, 1985. [3] jacob k. “computation of the flow around wings with rear separation”, journal of aircraft, vol.21, no. 2, february 1984, pp.9798. [4] cebeci t., lark r.w., chang k.c., halsey n.d. and lee k. “airfoils with separation and the resulting wake”, journal of fluid mechanics, vol. 163, february 1986, pp. 323-347. [5] nilay sezer-uzol “high – accuracy wake and vortex simulations using a hybrid euler/ discrete voortex method”, m.sc. thesis, department of aerospace engineering, the pennsylvania state university, may 2001. [6] moran j., cole k. and wahl d. “analysis of two-dimensional incompressible flows by a subsurface panel method”, aiaa journal, vol. 18, no. 5, may 1980, pp.526-533. [7] moran j. “an introduction to theoretical and computational aerodynamics”, john wiley & sons, 1984. [8] chang p. k. “control of flow separation”, mcgraw-hill book company, 1976. [9] leishman j. g., galbraith r. a. and hanna j. “modeling of trailing edge separation on arbitrary tow-dimensional aerofoils in incompressible flow using an inviscid flow algorithm”, glasgow university aero report no. 8202, may 1982. [10] chow c. y. “an introduction to computational fluid mechanics”, john wiley & sons. 1979. [11] john j. bertin and michael l. smith “aerodynamic for engineers”, prentice-hall, 1979. [12] yeh and a. plotkin “vortex panel calculation of wake rollup behind a large aspect ratio wing”, aaia journal, vol. 24, no. 9, september 1986, pp 1417 – 1423. [13] suciu and l. morino “nonlinear steady incompressible lifting – surface analysis with wake roll-up”, aiaa journal, vol. 15, no. 1, january 1977. laith w. ismail al-khwarizmi engineering journal, vol. 4, no. 2, pp 59-68 (2008) 68 بحث توزيع الحمل والضغظ على الجنبح مع التفبف دوامبت األثر لطبئرة ذات سرعة واطئة ليث وضبح اسمبعيل انغبيؼخ انزكُىنىعُخ/ قسى هُذسخ انًىاد الخالصة َزضًٍ انجؾش انؾبنٍ طشَقخ رؾهُم أونُخ ًَكٍ اسزخذايهب نؾسبة رىصَغ االؽًبل وانضغىط ػهً االعُؾخ فٍ انسشع انىاطئخ يغ وعىد ؽُش رى سثظ طشَقخ اششطخ انذوايبد يغ َظشَخ انخظ انؾبيم انؼذدَخ ثىاسطخ اسهىة ركشاسٌ . ظبهشرٍ أَفصبل انغشَبٌ وانزفبف دوايبد األصش رى ثُبء ػذح ثشايظ فٍ انؾبسىة ثبسزخذاو نغخ فىسرشاٌ ورًزبص هزِ انجشايظ ثكفبئزهب . يزضًُبً ًَىرط اَفصبل انغشَبٌ وًَىرط انزفبف دوايبد االصش . واسزقشاسَزهب نُست (naca 0012 and ga(w)-1)رى ثؾش ايكبَُخ انطشَقخ انؾبنُخ يٍ خالل ػذد يخزهف يٍ انؾبالد ألعُؾخ راد يقبطغ يخزهفخ رضًُذ انُزبئظ يُؾُُبد انشفغ وانكجؼ ورىصَغ انشفغ وانضغظ ػهً طىل ثبع انغُبػ, رى االخز ثُظش االػزجبس رأصُش , ثبػُخ وصواَب هغىو يخزهفخ رىصَغ انضغظ ػهً االعُؾخ ثٍُ اٌ هُبك يُطقخ انضغظ انضبثذ ػهً انسطؼ انؼهىٌ . صواَب انهغىو وانُست انجبػُخ ػهً انزفبف دوايبد االصش قىسَذ انُزبئظ . نألعُؾخ قشة انؾبفخ انخهفُخ فٍ يُزصف انغُبػ, كًب وعذ اٌ هُبك يُطقخ اَفصبل نهغشَبٌ ػهً انسطؼ انؼهىٌ نالعُؾخ . انًسزؾصهخ يغ أخشي رى انؾصىل ػهُهب يٍ ثؾىس يُشىسح وقذ ظهش رقبسة عُذ ثُُهب انُزبئظ انًسزؾصهخ ثُُذ اٌ انطشَقخ انؾبنُخ قذ رًكُذ يٍ االؽبطخ ثًخزهف ظىاهش انغشَبٌ ػهً االعُؾخ يضم اَفصبل انغشَبٌ وانزفبف . دوايبد االصش automatically optimization the element of cutting condition al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 5, no. 2, pp 44 53 (2009) automatic optimization system of cutting condition for different types of machining processes ali h. kadhum* and huda hatem** manufacturing operation department/ al-khawarizmi college of engineering/ university of baghdad *email: kadhumali59@yahoo.com **email: hoda_abode@yahoo.com (received 10 november 2008; accepted 2 june 2009) abstract this research aims at calculating the optimum cutting condition for various types of machining methods, assisted by computers, (the computer program in this research is designed to solve linear programs; the program is written in v. basic language). the program obtains the results automatically, this occur through entering the preliminary information about the work piece and the operating condition, the program makes the calculation actually by solving a group of experimental relations, depending on the type of machining method (turning, milling, drilling). the program was transferred to package and group of windows to facilitate the use; it will automatically print the initial input and optimal solution, and thus reduce the effort and time required for the calculations, that helps to find the optimum values for the cutting system. optimum values improved mechanical properties (wear, fatigue, strength …) and gave better productivity. keywords: technical constraints, mathematical model, optimization, element of cutting condition, package, machining processes, factors, cutting parameters, date base. 1. introduction the typical technological environment becomes more complex concerning types of parts, materials, machines, tools and job. it is obvious that the optimum of cutting conditions can be a very complex and time consuming job requiring a large a mount of data. this is further complicated by the fact that the cutting condition is a critical element in making the part correctly and economically [2, 8]. modern industries need not only calculating the cutting systems by formulas, but also requiring the selection of the optimum cutting system for specific work piece, and then maintaining this system along the time of cutting. this requires that all factors with elements of a system known and fixed in advance [7]. to select the condition for the working tools, all the parameters of the process must be known, and this ensures greater efficiency, for the conditions of production, in the implementation of the requirements of the cutting conditions. it also must conform the technical parameters to the available cutting parameters [3,4,9]. . to work the calculation of the optimum cutting condition, the difficult relations between the various factors that describes the operation must be taken into account. the parameters describing this processes are divided into inside and outside, and they also describe the difficult functional relationships between them. total relations give a mathematical model for machining processes. to find the optimum values in the calculation of the cutting conditions, acknowledgment of set of variables can guide in the cutting process (such as tool life, geometry of tool, the cutting thickness...). to select the criteria, it is necessary to include more influential working parameters. to build a flowchart, certain cases were analyzed after the selection of parameters, and the evaluation of the information is possible, and then ali h. kadhum al-khwarizmi engineering journal, vol. 5, no. 2, pp 44 -53 (2009) 45 using functional relationships among the inside and outside parameters at specific values (maximum rang) was put the aim in function. the data base that must be developed contains specifics about available machines, tools, materials, stock removal, type of cuts that can be made by a particular machine, and tolerance information with regard to cutting conditions, machinability information [5]. a large data base and some complex calculations are required to accomplish this. 2. technical constraints of cutting condition the expression of technical constraints [4, 6] of the inequality types ≤ or ≥, for cutting condition, could imagine the relationship between the variables and the elements of the cutting system (t, n, and ƒ), which were constant as the operation was under one way. the technical constraints at the optimum calculation cutting system widely depended on the type of operation [7]. the choice of optimum values of feed and cutting speed is made more difficult by several constraints which must be satisfied along with the equations discussed in this paper. these are: 2.1. available cutting tool cutting speed has significant effect on the tool life, tool geometry, depth of cut, feed and surface finish. for turning machining processes the cutting speed can find with formula: v v xm y dtt cvkv nf 318  … (1) 2.2. available horse power of machine tool effective machining forces and power are seldom classified as process boundaries. the power required during a cutting operation depends on the cutting speed and feed, and may be expressed for different types of machining as: z uynzx z cnyn kzbdtc kn fn zzzzz zzz    … (2) the maximum available power for cutting is a limited value which can be obtained by subtracting the transmission losses from the horsepower of motor provided on the machine. 2.3. machining production rate in the cutting processes with an edged tool, the parameters which affect the machining rate are cutting speed and feed. the higher the values of these parameters, the less the machining time, the and the machine operation time. the following formula can express this: rtrk lr nf hbrl .60   … (3) 2.4. available cutting speed and feed on machine tool machine tools in general are equipped with only a limited rang (max, min) of cutting speed and feed and that too in step variations. calculating the cutting speed and feed is consistent with the restrictions of the machine tools that range as: minnn  … (4) minff  … (6) maxnn  … (5) maxff  … (7) 2.5. strength of cutting tool this constraint clarifies the relationship between the calculated cutting speed with feed and the allowable strength of the cutting tool. the limit of strength of metal fixture under the effect of bending can be obtained by the following restrictions, when turning. zfspb nnx z n yn kkldtc bh fn zzz z zz .. 32 )10(4   … (8) 2.6. cutting tool rigidity the workpiece material, size and configuration determine the type of machining operation and the cutting tool to be used. because of the cutting forces involved, the tool deflects causing a ali h. kadhum al-khwarizmi engineering journal, vol. 5, no. 2, pp 44 -53 (2009) 46 detrimental effect on the tool life, surface finish and dimensional accuracy; the deflection of the tool may assume undesirably high values, and the cutting forces and tool deflections must be kept within limits, and this can be expressed as: zpb nnx z n yn kldtc bh fn zz zz 3 . 313 2 )10(    … (9) 2.7. work piece rigidity interested in these constraint terms, the amount of occupied deflection under the influence of the cutting force shall be less or equal to the allowed deviation, and we get a technical restriction for workpicece rigidity. 2 . 2 . 341 )(64 )10(5.1 ppwp n y x y pw n n n yn xlxdktc lde fn yy y p y yy     … (10) 2.8. strength of feed mechanism unit it is the relationship between the calculated cutting speed and feed. with the strength of feed mechanism, the following relationship holds: s unznx s donssyn kbzdtc pn yn ssssss ss   )10( 3 … (11) 2.9. requirements surface finish for many machined components the surface roughness is an important criterion for their acceptance. a detailed discussion on surface roughness produced by various cutting processes, in turning is a function of a number of variables, tool material, tool geometry, cutting conditions and wear of tool. the parameters of tool geometry that affect the surface finish are the side, end cutting edge angles and the nose radius. the theoretical values of ro (ra, rz, rmax) are realized only at high cutting speed. the variation in feed directly affects the surface roughness because of the feed marks made by the cutting edge tool. for a particular cutting operation the surface finish restriction may be expressed as: 7654 32 11 kkkk kk rtk ro fn   … (12) 3. mathematical model to calculate the elements of cutting condition cutting condition should be optimum and the final part should be realized by a specified time and by allow production cost. all this leads to the need for computerized systems that will allow the cutting condition function to be performed by a computer, providing the user with optimum cutting condition in quick consistent fashion. the calculations depending upon the different machining processes involved are:  turning and facing – cylinder.  drilling, reaming and boring – hole.  end milling, slab milling, face milling, side milling, slot millingdifferent surface. the first problem to be solved is bringing all the technical constraints and evaluation function to a linear form. for example, consider bringing to linear form the first line of technical limitations in equation (12) using a logarithm method [1, 7]. )ln(lnln 7654 3 kkkk l z rtk ro fknk   … (13) entering symbols 21 )100ln(,ln xfxn  12 6 )ln( 7654 b rtk ro kkkk   and the bases of their constraints [12], we get 122312 bxkxk  … (14) similarly, it can be obtained from the linear equation which depends on other technical constraints. analysis of earlier criteria for best value shows that optimizing the two elements of the cutting system n and ƒ without changing: max)( 21  xxfo … (15) the transformation of technical limitations to the linear forming and presenting them in the form of inequalities in conjunction with evaluation ali h. kadhum al-khwarizmi engineering journal, vol. 5, no. 2, pp 44 -53 (2009) 47 function gives a mathematical model of the process of cutting metal [7].            nnn bxyxz bxyxz bxyxz 21 22212 12111 . . … (16) with regard to the mathematical model (15) to determine the optimal cutting system is to find among all kinds of non-negative values of x1 and x2 systems the optimum values x1opt, x20pt where the linear function takes the maximum value of ƒ0 max. [6]. the theory of linear programming shows that the extreme importance of the evaluation function is provided for x1 and x2, are at a point lying on a boundary straight lines or intersections . the task of finding the best values x1opt and x2opt is the consistent consequence calculation of the coordinates for all possible intersection points of the boundary and then to find the maximum summation . ƒ0=(x1+x2) → max after positioning x1opt and x20pt calculate the optimal values of the elements of the cutting condition in the formula : nopt = exp (x1opt); ƒopt = exp (x20pt) / 100. to determine the optimal solution of the problem, for linear equations system and inequalities, simplex method is commonly used. determine a pair of points intersecting the straight lines and putting this points in inequalities system. a point, which coordinates satisfy everyone without exception. any straight line (check the compatibility of the system of equations) at the same time of the summation of the coordinates (x1+x2), will be a maximum and an optimum point [6]. 4. flow chart to find the optimum condition the flow chart in (fig.1) starts by selecting the type of machining process; then introducing all the necessary information about the workpice (diameters, lengths, allowance, roughness, production rate and the depth of cut). then the user makes a selection for different types of working materials, added to the program as a data base; after that select the type of turning machine. [5] starting the operation of program, the first window is shown (fig.2), then put the information about the workpiece and select the work materials; then select the type of machine, after that click (next) to translate to the second window (fig.3) which contains types of tool materials that must be selected, according to the type of working material, then select the dimensions of the tool and type of machine work, from these many conditions the program will find all the factors according to the data base. these factors are used with requirements of the inequalities equations, and then the program will calculate and solve all the inequalities equations to find the optimum values. the third window (fig4) and fourth window (fig.5) shows the result of the calculation, the optimum value for cutting speed and cutting feed and all the information about the cutting condition. ali h. kadhum al-khwarizmi engineering journal, vol. 5, no. 2, pp 44 -53 (2009) 48 fig. 1. general flow chart to calculate the optimum cutting condition ali h. kadhum al-khwarizmi engineering journal, vol. 5, no. 2, pp 44 -53 (2009) 49 fig.2. select one of the different types of machining processes fig.3. input the data and select the parameters of machining process ali h. kadhum al-khwarizmi engineering journal, vol. 5, no. 2, pp 44 -53 (2009) 50 fig.4. select the parameter of machining fig. 5. final results ali h. kadhum al-khwarizmi engineering journal, vol. 5, no. 2, pp 44 -53 (2009) 51 5. procedure of linear programming the sequences of solving equations are: 1. examine a pair of straight lines and make their checks to parallel at the same time. 2. if straight lines are parallel, examine the next pair, but if the straight lines are not parallel, then determine the coordinates of x1and x2 to the point of the intersection. 3. check the signs of coordinates. if the coordinates are positive, then through the permutations in each of the inequalities found, the value of x1 and x2 will be determined, whether the point in the field of possible solutions. if any one of inequalities is not satisfied, then this point is discarded and conducted the same analysis for the next pairs. 4. if x1and x2, are positive and satisfy all the inequalities without exception, then determine the summation of the coordinates δo = x1+x2 and store in the form of some significance a. all the above steps are followed until all pairs of straight lines are considered. 5. in the case of inconsistencies in the original data may show that there is the no field of possible solutions. a sign with out joint the system is equal to zero value of a, which otherwise is the sum of coordinates x1+x2, and will be the solution of the problem. 6. if the decision is on the line, it is parallel to the evaluation function, where a decision is taken by the coordinates of the point, more than coordinate x2 (i.e. when more than the value of the feed). 7. if the system's inequalities together and found the point, an summation the coordinates x1+x2 to be the maximum, so, the optimum cutting speed is 1x en  and the optimum feed is 100/2x ef  . 6. case study this case study describes how to use this package. we show how the problems listed and solved by the program in a typical interactive computer session. in the first window (fig.2); we must enter the information about the workpiece d = 20mm l = 50mm a = 1.2mm ra = 0.8μm r = 15 piece/hr, then select working materials carbon steel, 1213, cnc turning machine (nmin=12.5rpm, nmax=2000rpm) in the second window (fig.3) we must select the tool material-cemented carbide (p05) tool dimension -16*10*100(b*h*l) external longitudinal turning work relief angel = 10 deg. rake angel = 15 deg. from this choice condition, the optimum cutting condition is achieved as the following: cutting speed (rpm) = 800 cutting feed (rev/mm) = 0.56 see fig.5 7. conclusion traditionally cutting conditions has been performed manually or by using tables by most companies. this package used to automate this function, and two approaches are considered, first: develop optimum and consistent individual calculation for each part. reducing the number of errors made in preparing the calculations. second: minimize the cost of production, time of production and maximize profit rate. 1. this work is one of the ways that can be automatically calculate the optimum cutting condition to allow simplification of product manufacture. 2. automatically calculating the optimum cutting conditions is an important element in (cad/cam) integration because it provides a basis. 3. reduce the amount of manual effort and time required to prepare the optimum cutting condition. 4. this package provides a data base of manufacturing knowledge that can be readily accessed. ali h. kadhum al-khwarizmi engineering journal, vol. 5, no. 2, pp 44 -53 (2009) 52 nomenclature a allowances, mm b width of shank, mm b width of milling cutter c1 constant, independent cmin min. cost d diameter of details in mm dnp translate diameter for multistage shaft e module of elasticity ƒ feed, rpm h height of shank, mm kl loading factor k fs . safety factor l total length of shank, mm l the length of details, mm lw.p. length of work piece ℓb.p. part of total tolls length, mm m variable indicator n power of machine, kw nmax maximum velocity of machine, m/min nmin minimum velocity of machine, m/min r production rate, piece/hr r noise radius, mm rr number of workpiece ro surface of roughness, μm (ra, rz, rmax) t tool life, min t depth of cut, mm t b.h. time, min psdon allowable force, kn xp distance from right edge to the position of the force η efficiency of machine σ stress, mpa z number of cutting teeth δ tolerance, mm cs, cy, cz, constant factor (5) cv k1, k2, k3, k4, k5, k6, k7 empirical factor (5) kv , ks, ky, kz, kcz correction factor (5) ns, ny, nz, indicator of degree (5) xs, xv, xy, xz indicator of degree (5) ys, yv, yz indicator of degree (5) rs, rz , us, uz, zs, zz indicator of degree (5) 1 , 2 , λ angles, degree 8. references [1] hamdy a. taha, operations research. macmillan publishing company, new york, fourth edition 1987. [2] dr.surender kumar, dr. a. k. jha; technology of computer aided design & manufacturing (cad/cam:cae) dhanpat rai and sons 1993. [3] erik oberg and others, machinerys handbook, 24 th edition, new york [4] v.v. arabatti and others, production technology, mcgraw-hill, mew delhi. [5] a.g. kocelovoy and r.k. mesheryakova , machine building technology, handbook,voi.1,2, moscow, 1985. [6] v. e.averchenkov and others, system automatically project-technological processes, minck-1993 [7] yascheritsin p. i. and eremenko m.l. theory of cutting , minck-1990. [8] u. rembold, b.o. nnaji, a. stoor; computer integrated manufacturing and engineering; wesiey publishing inc. 1993. [9] serope kalpakjian and stevaen r.schmid, manufacturing engineering and technology, fifth edition, by person education, inc.,2006. 53 44، صفحة 2، العذد 5مجلة الخوارزمي الهنذسية المجلذ علي حسين كاظم (200 9) 53 حساب نظاو انقطغ انًثاني اًذٌياذيكيا نًخرهف أنٌاع ػًهياخ انرشغيم **هذى حاتم* كاظم حسينعلي جايؼح تغذاد/ كهيح ىنذسح انخٌاسصيي/ قسى ىنذسح ػًهياخ انرصنيغ (kadhumali59@yahoo.com ):انثشيذ االنكرشًني* (hoda_abode@yahoo.com) :انثشيذ االنكرشًني ** الخالصة ذى ذصًيى تشنايج يساػذ ػهى حم يحذداخ نظاو انقطغ , ييذف انثحث انى حساب نظاو انقطغ انًثاني نًخرهف أنٌاع ػًهياخ انرشغيم تًساػذج انحاسٌب ًرنك . اًذٌياذيكيا (انرغزيح ًسشػح انقطغ ) انقطغ ويقٌو انثشنايج تحساب انقيى انًثانيح نؼناصش نظا. انثشنايج كرة تهغح انثيسك , تطشيقح انثشيجح انخطيح يقٌو انثشنايج تحساب دقيق ًرنك تحم يجًٌػح ين انؼالقاخ انرجشيثيح تؼذ ذحٌيهيا إنى , تؼذ إدخال انًؼهٌياخ األًنيح ػن انًشغٌنح ًحانح ػًهيح انقطغ انثشنايج يقهم ين . ذى ذحٌيم انثشنايج انى يجًٌػح ين انٌاجياخ نرسييم اسرؼًانو . (ذفشيض ,ذثقية ,خشاطح )يٌديم سياضي ًحسة نٌع طشيقح انرشغيم . ىزه انقيى انًثانيح ذحسن ين خٌاص انًشغٌنح ًذساػذ ػهى صيادج اإلنراجيح, انجيذ ًانٌقد انضائغ في انحساتاخ انًثانيح ألنظًح انقطغ mailto:kadhumali59@yahoo.com mailto:kadhumali59@yahoo.com mailto:*%20������ mailto:*%20������ mailto:*%20������ mailto:hoda_abode@yahoo.com mailto:hoda_abode@yahoo.com (microsoft word \343\321\315 \346 \317 \323\307\343\3556069) al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 15, no. 3, sptember, (2019) p. p. 6069 adsorption of heavy metals from aqueous solution onto sawdust activated carbon marah w. khalid* sami d. salman** *,**department of biochemical engineering/ al-khwarizmi college of engineering/ university of baghdad/ iraq *email: sami.albayati@gmail.com (received 4 february 2019; accepted 7 april 2019) https://doi.org/10.22153/kej.2019.04.001 abstract in this study, sawdust as a cheap method and abundant raw material was utilized to produce active carbon (sdac). physiochemical activation was utilized where potassium hydroxide used as a chemical activating agent and carbon dioxide was used as a physical activating agent. taguchi method of experimental design was used to find the optimum conditions of sdac production. the produced sdac was characterized using sem to investigate surface morphology and bet to estimate the specific surface area. sdac was used in aqueous lead ions adsorption. adsorption process was modeled statistically and represented by an empirical model. the highest specific surface area of sdac was 688.3 m2/gm. langmuir and freundlich isotherms were used to fit the adsorption process, where equilibrium data was best represented by langmuir isotherm model. pseudo-first order and pseudo-second order equations were used to study adsorption kinetics, lead adsorption on sdac fitted pseudosecond order more adequately. best removal efficiency was found to be 99.63% with highest adsorption capacity of 19.92 mg/g. keywords: adsorption, activated carbon, sawdust, lead, physiochemical activation. 1. introduction due to the wide range and the exaggerated uses of organic solvents, oxidizing agents, phenols and heavy metals in industry, they were accumulated in the environment which caused ecosystems deterioration. heavy metals category is one of the most lethal pollutants of surface and ground waters. industrial effluents are the major source. since most of heavy metals could not be degraded into benign components, removing the heavy metals before discharging waste waters into rivers becomes necessary. otherwise they could be harmful to the health and/or reduce drinking water quality [1]. according to the world health organization (who, 1984) and international program of chemical safety (ipcs, 1988), the most poisonous metals are aluminum, zinc, mercury, arsenic, chromium, nickel, copper, cadmium and lead. the drinking water guideline value recommended by world health organization (who) and iraqi standard regulation is 0.01 and 0.015 mg pb/l. lead is found in freshwaters due to its wide uses in petroleum refining, batteries industry, preparation of nuclear fuels and electroplating. lead causes severe damage to human organs e.g. kidneys, the brain, reproductive system, the liver and the nervous system [2]. as a result of the toxicity of the lead and its compounds, removal method has become an marah w. khalid al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 6069 (2019) 61 important priority. there are various available means to reduce heavy metals levels from water including ion exchange, membrane filtration, chemical precipitation and reverse osmosis, but these methods generally require high cost and produce more lethal by products [3]. adsorption on solid materials is one of the best existing methods for improving the water quality and the regulation of atmospheric and aquatic pollution, with active carbon being the most used adsorbent in industry. in the last years, worldwide consumption of active carbon has increased by an annual average of 5.5% , and it is anticipated to continue to do so at a higher rate in next years (8.1% in 2018)[4]. thus, locally produced wastes such as saw dust, cow bones, and others were examined for preparing active carbon. because of the low cost of those wastes, high percentage of carbonaceous contents and their abundancy, they were found to be of high potency in heavy metals adsorption. the aim of this study is to optimize the production of activated carbon from sawdust by physiochemical activation method and to evaluate its adsorption potential for the lead ions aqueous solution. adsorption isotherm fitting and kinetics studies were conducted to understand the behavior of lead ions onto sdac. effective parameters such as initial ph of the metal solutions, contact time, initial metal concentrations and temperature were investigated. 2. materials and methods 2.1. adsorbate technical grade lead nitrate (pb(no3)2) of 99.8% purity provided by himediaindia was used to prepare stock solution of the lead. distilled water was used to prepare all solutions. a stock of 1000 mg/l was prepared by adding (1.68) gm of pb(no3)2 to a liter of distilled water. other solutions were prepared by diluting the stock solution to the required concentrations. naoh and hno3 solutions each of 0.1 m concentration were used to adjust ph value. 2.2. preparation and characterization of activated carbon saw dust (sd) was obtained from local furniture workshops, baghdad, iraq as waste. the preparation methodology of sdac is concisely illustrated in figure.1. the surface area was analyzed using brunaureemmett-teller (bet: horiba, sa-900 series, usa) through nitrogen adsorption isotherm at 77 k. in order to determine the shape of sdac surface and pore characteristics, the samples were scanned using scanning electron microscope (tescan, vega iii, czech republic). 2.3. design of experiments experimental design usually used to efficiently map the set of experiments to be conducted and to serve the following: understand the effect of the factors and/or model the relationship between response and factors with a minimum number of experiments [5]. taguchi method was used in the optimization of sdac production and in modelling of adsorption process due to its efficiency compared to other methodologies and its robustness. statistica 10 (stat soft, inc. usa) was used to design the set of experiments. where l9 orthogonal array was chosen (2 factors, 3 levels) in sdac preparation, and l25 array (4 factors, 4 levels) for adsorption process modelling. marah w. khalid al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 6069 (2019) 62 fig. 1. schematic diagram for the sdac preparation steps. 2.4. batch equilibrium studies bach mode adsorption experiments were conducted by adding specific amount of adsorbent to a 100 ml lead solution contained in 125 ml capped plastic containers. the containers were placed in an isothermal shaker (jssi-300cl, jsr, korea) at agitation speed of 180 rpm. after adsorption time was completed, all samples were filtered from the adsorbent with whatmen filter paper to make it carbon free. the remaining concentration of the lead in each sample after adsorption was determined by atomic-absorption spectroscopy (shimadzu aa6200, japan). the lead adsorption capacity on sdac was predicted according to: �� = ������ � … (1) where co and ce are the concentrations of the lead at initial and equilibrium conditions (mg/l) respectively; v is the volume (l); and w is the weight (g) of sdac. 2.5. adsorption isotherm langmuir and freundlich isotherm models were used to fit the equilibrium data. the linear form of the langmuir [6] model is: � � = � � + � ��� � � �� …(2) where ce (mg/l) is the concentration of the lead at equilibrium; qe (mg/g) is the equilibrium adsorption capacity; qm is the adsorption capacity for a complete monolayer (mg/g); ka (l/mg) is the constant of adsorption equilibrium. the linear form of freundlich [7] isotherm is: ln �� = ln �� + �� �� ln �� …(3) the constants kf (mg/g) and n are freundlich constants. 2.6. kinetic studies the adsorption rate constants were predicted from the pseudo first-order and pseudo secondorder kinetic equations. pseudo first-order [8] expression is : log��� − �� = log �� − ��� ."#" … (4) where qe and qt (mg/g) are the adsorption capacities at equilibrium and at time t (min), respectively and k1 (1/min) is the adsorption constant. the linear form of the pseudo second-order kinetic model [9] can give by: � $ = � �% �% + � � & …(5) where (qe) is the adsorption capacity of equilibrium and the constant of second order k2 (g/mg h) can be determined experimentally from the intercept and slope of t/qt versus t plot. marah w. khalid al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 6069 (2019) 63 3. results and discussion 3.1. sdac production and optimization the experiments that were conducted are shown in table 1. table 1, preparation of sdac experimental design array and the results for ssa and yield. in sdac preparation, the ssa increases as ir rises from 1:2 to 1:3. the clarification of this results is that the reduction of koh occurs during activation process was transformed to potassium oxide by dehydration reaction. potassium oxide reacts with carbon dioxide that is provided during physical activation to form k2co3 which aids to form new pores and widen pores that formed during chemical activation. so it was recognized that above 420 co (melting point of koh), the surface area of carbon activated by koh is more than the area of carbon activated by k2co3 [10]. but when the ir reached to 1:4 the ssa decreased. this was probably due to excessive potassium hydroxide molecules decomposing into metal. as a result, metal deposition on the already developed pores might occur and lead to reduction of the surface area [11]. regarding the activation temperature effect, it was perceived that as the temperature rises from 600 oc to 700 oc ssa increases. these results can be explained by the following: as the temperature increases, more koh evaporates which enhances the surface porosity [12]. on the other hand, ssa decreased as the temperature reached to 800 oc, this is due to the fact that elevated activation temperatures cause pore dilation which lead to explosion/collapse of pores, that led to the lower values of specific surface area [13]. in general, the sdac yield was found to be inversely proportional to both temperatures of activation and ir. as the temperature elevates more volatile components will be released due to intensified dehydration and elimination reaction that increase c-koh and c-co2 reaction rate which causes lower weights of sdac [14]. moreover, the yield decreased with increasing ir. potassium hydroxide promotes the oxidation process, with high koh ratio, the gasification of surface carbon atoms is the predominant reaction leading to increase in the weight loss of carbon [15]. 3.2. sem and bet analysis fig. 2 shows the sem images of sd and sdac. it can be noticed that sdac surface has developed pores in which there is a good probability for the lead to be adsorbed. bet surface area was 688.62m2/g. average pore diameter for sdac was 5.675µm where it is larger than 50 nm that agrees with iupac categories of macro porous materials within the stated range [16]. the high ssa of the sdac was a result of the used technique of activation. the activation process involved chemical and physical activating agents which are koh and co2 respectively. however, the developed pores during carbonization enhanced the surface area by diffusing more co2 and koh molecules inside the pores, therefore; the reaction between koh-carbon and co2-carbon promoted leading to more pores in the activated carbon. sdac preparation responses sdac preparation variables runs yield (%) specific surface area (m2/gm) activation temperature (cᵒ) ir 81.6 161.7 600 1:2 1 73.7 428.5 700 1:2 2 42 365.8 800 1:2 3 80.2 267.8 600 1:3 4 71.5 688.3 700 1:3 5 37.9 653 800 1:3 6 72.6 367.1 600 1:4 7 62.7 626.1 700 1:4 8 35.4 611.9 800 1:4 9 marah w. khalid al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 6069 (2019) 64 fig. 2. sem images (a) precursor and (b) sdac (magnifications: 1000x) 3.3. batch equilibrium studies batch adsorption experiments were conducted by adding 0.25 g of sdac with 100 ml of prepared lead solution of various concentration (10, 20, 30, 50mg/l) with different initial solution ph ranging from 2 to 5. the experiments were accomplished in different contact times within the range of 10-40 minutes. the temperature range was 20-50 ᵒc where the temperature was controlled by using thermal shaker. another set of experiments with time ranging from 30-300 minutes was conducted. results showed that almost all of the experiments that have contact time larger than 30 minutes with no lead was remained, time range was change to 10-40 minutes. 3.4. experimental design and empirical model the set of experiments that was designed by taguchi method and their results are shown in table 2. table 2, batch adsorption experiments and their response. initial concentration (mg/l) time (min) temperature (ᵒc) ph equilibrium concentration (mg/l) 10 10 20 2 10 10 20 30 3 2.992 10 30 40 4 1.911 10 40 50 5 2.132 20 10 30 4 3.175 20 20 20 5 2.402 20 30 50 2 13.322 20 40 40 3 3.131 30 10 40 5 2.707 30 20 50 4 3.539 30 30 20 3 7.356 30 40 30 2 4.141 50 10 50 3 3.701 50 20 40 2 3.304 50 30 30 5 3.5 50 40 20 4 3.202 a b marah w. khalid al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 6069 (2019) 65 the obtained model with its four factors and their interaction is represented by: ' = () + (�*� + ( * + ("*" + (+*+ + (� *�* + (�"*�*" + (�+*�*+ + ( "* *" + ( +* *+ + ("+*"*+ + (��*� + ( * + (""*" + (++*+ …(6) where b0, b1, b2, b3 and b4 are the linear coefficients, b12, b13, b14, b23, b24 and b34 are the second-order interaction terms, and b11, b22, b33 and b44 are the quadratic terms of each factor. y, x1, x2, x3 and x4 are the coded terms of equilibrium concentration, initial lead concentration, time, temperature and ph, respectively. the estimated values of the model coefficient, standard error of each model term, and its p value are shown in table 3. table 4, model coefficients, standard error and terms p values estimate standard error pvalue b0 0 b1 1.928 0.257 0.00 b2 -1.033 0.203 0.000002 b3 3.079 0.352 0.00 b4 -24.723 2.942 0.00 b12 0 b13 0 b14 0.031 0.002 0.05004 b23 0.004 0.00 0.00 b24 0.049 0.00 0.00 b34 0.037 0.003 0.00001 b11 0.004 0.001 0.00 b22 0 b33 -0.022 0.005 0.00 b44 1.603 0.466 0.001 bo, b12, b13 and b22 were eliminated from the model due to their insignificant values compared to others. their elimination did not affect the accuracy of the predicted model. 3.5 effects of factors 3.5.1 effect of contact time and pb(ii) initial concentration the influence of adsorption time on the lead ions adsorbed by sdac was investigated and presented in fig. 2. it was observed that removing the lead ions was fast through the first 20 min and removing efficiency of sdac increased with the initial lead ion concentration. the adsorption was fast at the initial stage because of the high driving force which induced the metal ions to transfer rapidly from the bulk solution to the surface of sdac [17]. with further increasing time, the availability of the uncovered surface area and the remaining active sites diminish and the decrease in the driving force makes it take long time to reach equilibrium for metal ions, and slowly diffusing into the intraparticle pores of the adsorbent. thus, the adsorption rate becomes slower [18]. it is also clear from fig. 2 that adsorption efficiency improved as the initial concentration of pb (ii) increased. this can be due to the fact that higher adsorbate concentration acts as a driving force for higher adsorption efficiency onto sdac [13]. similar trend of heavy metal adsorption, as a function of initial concentration, has also been reported previously by igberase [19] and trang [20]. fig. 2. effect of contact time and initial concentration on removal efficiency. 3.5.2. effect of ph and temperature the initial solution ph is the most significant factor to investigate the adsorption characteristic of an adsorbent because it affects not only surface charge of the adsorbent, but also the ionization degree and adsorbate speciation [21]. the effect of initial solution ph on the lead ion removal by sdac is presented in fig. 3. as the negative charge density on sdac surface increases due to cooh ionization, the adsorbed lead will rise rapidly [22]. marah w. khalid al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 6069 (2019) 66 at ph = 5, the efficiency on adsorption reached its maximum value. in order to assure a true investigation of adsorption characteristics of sdac and to avoid precipitation of the lead ions, all the experiments were run at ph <=5.0. this result is in line with al-malack and basaleh [23] and shi [24]. as temperature rises, the solution viscosity will slightly decrease which enhances the diffusion rate of the lead into the pores of sdac [25]. in addition to that, the high temperatures will break internal bonds at the edges of the active sites [26] which aids the enhancement of adsorption efficiency of the sdac. fig. 3 illustrates the direct proportion between temperature and efficiency of adsorption. as it can be seen from fig.3 that lead adsorption on sdac is endothermic process. this result corresponds with sulaymon [27] and adebisi [3]. fig. 3. effect of initial ph and temperature on adsorption efficiency. 3.6 adsorption isotherm studies the adsorption data of pb(ii) on sdac fitted langmuir isotherm more adequately with r2 value of 0.996. fig.4 shows the plot of 1/ce versus 1/qe. the results confirmed that the lead had formed a monolayer on the sdac outer surface with monolayer full coverage adsorption capacity of 13.65 mg/g. other studies had also confirmed the same results [28] and [29]. fig. 4 adsorption data fitted into langmuir isotherm. 3.7. kinetics studies to figure out the mechanism that controls the adsorption of the lead on sdac, such as physical interactions and chemical reaction, pseudo-firstorder and pseudo-second-order equations were utilized to model the kinetics of adsorption. fits better the experimental data (r2 = 0.996) than the pseudo-first-order model (r2 =0.974). the equilibrium adsorption capacity obtained from pseudosecond order (qe) was 24.19 mg/g and second order constant k2 = 0.0053 (g/mg h). other researches had confirmed the same results [30] and [29]. 4. conclusion the results of this study showed the active carbon that prepared from sawdust using physiochemical activation is a favorable adsorbent for the lead adsorption from aqueous solution over a wide range of conditions. langmuir and freundlich isotherm models were utilized to fit the data of equilibrium and the equilibrium data for sdac were found to be well represented by the langmuir isotherm. the kinetics of adsorption followed the pseudo secondorder kinetic model. the empirical model represented the adsorption process accurately with r2 value of 0.988. based on the high range of removal efficiencies, sdac can be used as a cost effective, and inexpensive substitute to the commercial activated carbons. marah w. khalid al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 6069 (2019) 67 5. references [1] q. dai, l. ma, n. ren, p. ning, and z. g. longgui, “research on the variations of organics and heavy metals in municipal sludge with additive acetic acid and modified phosphogypsum,” water res., vol. 155, no. 15 may 2015, pp. 42–55, 2019. 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[30] m. ghasemi, m. naushad, n. ghasemi, and y. khosravi-fard, “a novel agricultural waste based adsorbent for the removal of pb ( ii ) from aqueous solution : kinetics , equilibrium and thermodynamic studies,” j. ind. eng. chem., vol. 20, no. 2, pp. 454–461, 2014. )2019( 6069، صفحة 3، العدد15دجلة الخوارزمي الهندسية المجلم مرح وليد خالد 69 متزاز المعادن الثقيلة من محلول مائي على كاربون منشط منتج من نشارة الخشبأ مرح وليد خالد* سامي داود سلمان** الهندسة الكيميائية االحيائية/ كلية الهندسة الخوارزمي/ جامعة بغداد*،**قسم sami.albayati@gmail.comالبريد االلكتروني:** الخالصة عن طريقه فعاله واقتصاديه إلزالته من المياه العادمة. في نتيجة لالستعماالت الواسعة للرصاص في الصناعة، باإلضافة الى أن اثاره الخطرة، وجب البحث يث تم استخدام هيدروكسيد هذه الدراسة، تم استخدام نشارة الخشب، كماده اوليه رخيصة، إلنتاج الكاربون المنشط. تم استخدام طريقه فيزيائية كيميائية للتفعيل، ح كعامل تفعيل فيزيائي. تم استخدام طريقة تاغوشي لتصميم التجارب إليجاد أفضل الظروف لتحضير البوتاسيوم كعامل تفعيل كيميائي وثنائي أوكسيد الكربون ) لمعرفة مساحته السطحية. betالكاربون المنشط من نشارة الخشب. تم تشخيص الكاربون المنتج بالمجهر االلكتروني للتحقق من شكله السطحي وتم استخدام ال( ن نشارة الخشب المتزاز ايونات الرصاص من المحاليل المائية. تم تمثيل عملية االمتزاز رياضيا بواسطة معادله قياسيه تجريبيه. تم استخدام الكاربون المنتج م رة غم. تم استخدام معادلة النغماير وفريندليتش لتمثيل عملية االمتزاز، حيث كانت العملية متطابقة بصو/٢م ٦٨٨٫٣اعلى مساحة سطحيه تم الحصول عليها هي از متوافقة بصورة كبيرة كبيرة مع نموذج النغماير. تم استخدام معادلة الدرجة األولى والدرجة الثانية الخاصة بدراسة حركيه االمتزاز، حيث كانت عملية االمتز ملغم/غم. ١٩٫٩٢مع أعلى قدرة امتزاز تصل الى %٩٩٫٦٣مع معادلة الدرجة الثانية. أعلى كفاءه امتزاز تم الحصول عليها بلغت <4d6963726f736f667420576f7264202d20c7c8d1c7e5ede320e6c7cde3cf20d2edcfc7e42031312d3138> al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 16, no. 4, december, (2020) p. p. 11-18 cloud manufacturing framework for controlling and monitoring of machines ibrahim kh. nayyef* ahmed z. m. shammari** *,**department of automated manufacturing engineering / alkhwarizmi college of engineering / university of baghdad *email: ibkh093@gmail.com **email: ahmadhzaam@yahoo.com (received 11 september 2019; accepted 6 september 2020) https://doi.org/10.22153/kej.2020.09.002 abstract due to the development that occurs in the technologies in information systems, many techniques were introduced and played an important role in the connection between machines and people through the internet, it is also used to control and monitor machines. these technologies are called cloud computing and the internet of things. with the replacement of computing resources with manufacturing resources cloud computing named converted into cloud manufacturing. the problem is that there are some materials that are not safe to keep workers in touch with it, or the manufacturing process needs the place to be kept clean, such as ic manufacturing, and these processes must be remote controlled and manufactured. in this research, cloud computing was used in the field of manufacturing to automate the process of selecting the gcode that the computer numerical control machine works with, this process was applied by using this machine with the radio frequency identification and some aws cloud services and some of the python libraries such as paho (the library that was used with the mqtt protocol) to establish the connection between devices. a present sensor value (a sensor called dht sensor) was used in this research to measure temperature and humidity in clouds to help the operator make decisions. this technology was used to eliminate paperwork, provide a real time monitoring of the machines, and allows the upper level of management to make their decisions about the products and its status to begin the shipping to the costumer. technology called “ethernet” over internet protocol has been used to control and monitor machines through a remote by using a mikrotik router device, and a virtual private network (vpn) was used to make a unique ip address for each machine. this research will solve the availability of worker mobility and the monitoring of the machines of a difficult machining material that is dangerous to workers life during the process. keywords: internet of things, cloud manufacturing, cnc machine, rfid sensor. 1. introduction cloud computing is coming into development step by step recently. on the off chance that we supplant the "figuring assets" with the "producing assets", the activity of the executive methods of the cloud computing can be acquired in the assembling field, which can be an original thought for the information development for the assembly ventures, therefore the idea of the cloud manufacturing is placed forward. based on the network with manufacturing and cloud computing, the cloud manufacturing is characterized as a server. the cloud manufacturing is a novel arranged assembling mode which uses the internet and the cloud ibrahim kh. nayyef al-khwarizmi engineering journal, vol. 16, no. 4, p.p. 1118 (2020) 12 manufacturing stage, sorts out different sorts of manufacturing assets (to be specific the manufacturing cloud web), and gives clients a wide range of services for their requests. it combines the current innovations of the organized assembling and administration with cloud computing, superior processing, the internet of things, and so on, to give each manufacturing action high quality and low-cost services whenever and anyplace on demand[1]. recently, researchers have been focusing on the cloud manufacturing and its capabilities, below there are many of researches: lihui wang intends to build up an internet and web-based administration situated framework for machine accessibility, checking, and process arranging. this paper especially proposes layered and capacity obstructs for the model. this framework engineering presents the iec 61944 execution. by interfacing with a wise-shop floor system, it empowers continuous machine accessibility and execution status observing during metal-cutting activities[2]. caggiano et al. proposed a research that used the cloud to monitor the materials that are difficult to machine, the system consists of multi sensors that are used to collect data from machines, according to a service oriented approach to review cloud capability, advance signal processing, and decision making was assigned to the cloud server. data that is taken from sensors gives the status of tool condition and the local servers are used to send commands to the machines. this research concludes that clouds are very important to enhance computing process and data storage that are collected from different resources to help decision making and increase the efficiency of tool condition diagnostics[3]. perez et al. proposed new assembling worldview called "cloud dexterous assembling". the primary goal for this work is to offer mechanical mechanization. it works as an administration to empower the clients in more elevated amounts to get to accessible functionalities of the computerization framework with the least unpredictability[4]. jan-peer rudolph and claug emmelmanna presented the additive manufacturing that is a part of industry 4.0 that is used to increase industrial production and how it was used to manufacture parts that are out of their cad data, these were accomplished by using cloud based platform that presents as a manufacturing services provider and also as an interface to the costumers. the point of convergence of the stage is on a mechanization of the request acknowledgment, the offer estimation, and the part screening for the distinguishing proof of fitting am parts [5]. xi (vincent) wang aimed to make a progress on the cloud manufacturing solution, called an interoperable cloud-based manufacturing system (icms), to create a fabrication platform that combines production services from the design to the manufacturing. in the icms environment, clients can submit production requests for as far as cloud service queries through a remote, via the network, with the help of the scm mechanism[6]. this research differs from the previous research in the use of cloud computing in the automation of cnc machines work by the use of rfid sensor that are attached to the product and has an id for each product to send this id to the cloud, telling the cnc to work a specific g-code and also to monitor the temperature of the cnc tool, and to send this information to an application to review it. 2. cloud manufacturing the cloud manufacturing is characterized as a novel arranged assembling mode which uses the internet and the cloud manufacturing stage, composes different sorts of assembling assets (specifically the assembling cloud) on the internet, and gives clients a wide range of administrations on their request. it combines the current advances of the arranged assembling and administration with cloud computing, superior processing, the internet of things, and so forth, to give each assembling movement high-caliber and minimal effort administrations whenever and wherever on interest. cloud manufacturing comprises of different assets, administrations, and answers for tending to an assembly task. any assembling ventures can utilize these assets, capacities, and learning to complete its assembling activities. inside a cloud assembly scene, an assembly endeavor doesn't have to have the whole assembling condition, for example, machines, it framework, and work force, or even programming, is engaged with assembling activities, for example, the plan, generation, the board, and strategic applications. an assembling organization can require the assets and administrations in the cloud fabrication stage alongside a compensation as-you-go evaluating approach[7]. ibrahim kh. nayyef al-khwarizmi engineering journal, vol. 16, no. 4, p.p. 1118 (2020) 13 3. internet of things the iot idea was authored by an individual from the radio frequency identification (rfid) advancement network in 1999, and it has lately turned out to be increasingly pertinent to the handy world generally in light of the development of cell phones, inserted and omnipresent correspondence, distributed computing, and information investigation. envision a reality where billions of articles can detect, impart, and share data, all interconnected over open or private internet protocol (ip) systems. these interconnected articles have information routinely gathered, broke down, and used to start an activity, giving an abundance of insight to arranging the board and basic leadership. this is the universe of the internet of things (iot)[8]. the web of things can be characterized as an interconnection between individuals, or articles that trade information over systems without including human-to-human or human-to-pc collaboration. iot offers different sorts of networks from gadgets, frameworks, and administrations that work inside machine-tomachine interchanges (m2m), and spread with applications, spaces, and conventions. 4. message queue telemetry transport mqtt is an open-sourced protocol for passing messages between multiple clients through a central broker. it was designed to be simple and easy to implement. the mqtt architecture is broker-based, and uses long-lived outgoing tcp connections to the broker. mqtt also supports hierarchical topic (e.g., “subject/sub-subject/subsub-subject”) file system structures [8]. mqtt can be used for two-way communications over unreliable networks where the cost per transmitted bit is comparatively high. it is also compatible with low power consumption devices. the protocol is light-weight (simple), and therefore well suited for constrained environments. mqtt has a mechanism for asynchronous communication and for communicating disconnected messages when a device has disconnected. the most recent message can also be stored and forwarded. multiple versions of mqtt are available to address specific limitations. fig. 1. mqtt protocol. 5. sensors sensors are an important thing in reading the changes in machine parameters such as tool temperature, spindle speed, and they order the object to select a code that is related to its shape, for this, an rfid sensor was used to sense the object and a dht sensor was used to sense its temperature. 6. radio frequency identification a radio frequency reader (rfid reader) is a gadget used to take data from an rfid tag, which is utilized to follow individual articles. radio waves are utilized to move information from the tag to a reader. the rfid is an innovation comparable in principle to standardized tags. notwithstanding, the rfid tag doesn't need to be examined straightforwardly, nor does it require an observable pathway to the peruser. the rfid label must be inside the scope of an rfid peruser, so as to be perused. rfid innovation enables a few things to be immediately checked and empowers quick distinguishing proof of a specific item, in any event, when it is encompassed by a few different things. figure 3 shows the rfid sensor components (tags and reader). ibrahim kh. nayyef al-khwarizmi engineering journal, vol. 16, no. 4, p.p. 1118 (2020) 14 fig. 2. rfid sensor component (tags and reader). 7. dht sensor dht is a sensor that is used to measure both humidity and temperature by the use of two-part capacity for humidity, and a thermistor for temperature, it spits out a digital signal because of the chip inside of the sensor that converts analog signals into digital signals, so it is easy to read with any controller. figure 4 shows the dht sensor. fig. 3. dht sensor. 8. mini cnc machine a mini cnc milling machine was used in this research to machine non-metal materials such as wood and acrylic. its controlled by a controller called “grbl 0.9j” and has 3 axis motions (x, y, z) controlled by a stepper motor (nema 17) working at 12 v with 1.8 step size and has a spindle motor with a voltage of 12-24 v[9]. the figure below shows the cnc milling machine. fig. 4. cnc milling machine. 9. experimental work the proposed research was presented as a prototype of the manufacturing shop floor, it was designed to fit the communication between machines in the industry, and also to support the remote controlling of machines. the system design contains several things, first, two machines named as “computer numerical control" (cnc) that connects to a personal computer (pc) that works as a controller of the cnc (local server store cnc program and takes orders from the cloud). second, sensing devices that contain two sensors for radio frequency identification (rfid) and dht 12, the third one is the cloud service that is called “brochure” that used the message queuing telemetry transport (mqtt), and a dashboard was used to monitor the status of machines and monitor the message between machines. figure 5 shows the parts that work. ibrahim kh. nayyef al-khwarizmi engineering journal, vol. 16, no. 4, p.p. 1118 (2020) 15 fig. 5. work diagram. the connection between the sensors and the raspberry pi will be shown in table (1) for the rfid sensor, and table (2) for dht sensor. table 1, connection of rfid with raspberry pi. pins raspberry pi pins vcc pin 1 3.3v rst gpio 25 gnd pin 6 (gnd) miso gpio 9 mosi gpio10 sck gpio 11 ss gpio 8 table 2, connection of dht with raspberry pi pins rpi pins vcc pin 2 (5v) gnd pin 14(gnd) data gpio 4 fig. 5. sensors connection with raspberry pi. the connection between the cloud, cnc, and the sensor will be used a graphical user interface to make the connection, the same as figure 6. fig. 6. aws cloud connection with cnc and sensors. message of broker ibrahim kh. nayyef al-khwarizmi engineering journal, vol. 16, no. 4, p.p. 1118 (2020) 16 monitoring process of the messages between devices will be as figure 7: fig. 7. application of monitoring messages 10. result the system shown in figure 8 runs smoothly depending on several experiments, thus the rfid sensor sensing the product whenever it comes through it, works as a publisher, then publishes a message to the aws iot broker that streams this message to the cnc machine that works due to the g-code that is saved in its controller when it comes a message published that cnc completes its work. a dht sensor was used to monitor the status of cnc. the main result from this process is to show the ability of cloud computing to be applied on manufacturing processes in monitoring and controlling, so it can save time to operate transportation between machine and save the cost of labor. fig. 8. system prototype. the part that are produced from the process of automation shown in figure 9, it has a drilling and milling process performed by the mini cnc machine. fig. 9. final part produced by cnc machine. 11. transferring g-code to cnc machine file transfer protocol "ftp" is an open protocol used for sharing files through the net. files transferred from the "cad/cam" center to the cnc machine using "ftp" in this technique will sent a g-code from the workstation to the cnc machine using a war-ftpd 1.55 program. this method was applied to c-tek km-80d milling machining, as shown in figure 10, and the product that results from this operation is shown in figure 11. fig. 10. transfer of g-code to machine. fig. 11. final product of machining process. cnc raspberry pi dht 12 rfid pc ibrahim kh. nayyef al-khwarizmi engineering journal, vol. 16, no. 4, p.p. 1118 (2020) 17 12. conclusion 1. the automation process of the production lines can be applied by the use of cloud manufacturing, and it can also be monitored by using sensors. 2. the use of cloud manufacturing in the automation process will reduce labor force, help in decision making, and improves work efficiency. 3. cloud manufacturing can be used in the manufacturing process to increase system efficiency and productivity by reducing the time and cost that is required to make the system more reliable and robust. 4. the wireless transferring of g-code to cnc will 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[7] r. y. zhong, l. wang, and x. xu, “an iotenabled real-time machine status monitoring approach for cloud manufacturing,” procedia cirp, vol. 63, pp. 709–714, 2017, doi: 10.1016/j.procir.2017.03.349. [8] o. vermesan and p. friess, “internet of things – from research and innovation to market deployment,” in river publishers, 2013,ch.4, p. 143. [9] a. k. khudhier, a. z. m. shammari, and a. h. hamad, “industrial cad-cam system based remote manufacturing process using raspberry pi web server,” j. eng. appl. sci., vol. 13, no. 11, pp. 4193–4197, 2018, doi: 10.3923/jeasci.2018.4193.4197. ���� ��� )2020( 1118، "! � 4، ا���د����16 ا���ارز�� ا������� ا����� ا� اھ� 18 1 �0 ا/.ت و� ا+*&(إط�ر ا�&%��$ ا�# ��� &�� *���� ��� ��6 ز��ان � �� ا��4 ي**ا ا� اھ� **‘* � �� ��� ا ��ارز��ھ ��� ا� �/ �� � ا�� � / &%�$� #"�ادا ibkh093@gmail.comا .*-� ا, +�*و)�:* ahmadhzaam@yahoo.comا .*-� ا, +�*و)�:** �"7� ا� 1 %ت /� � �$���%ت )98)8ً*ا ���6ر ا 5ي -�3ث /� ا � دوًرا ��ً�% /� ا,��%ل # ? ا<,ت وا=>�%ص :.* ا.$ 1 %ت و� ، �9 إدa%ل ا $�-� �? ا 1 %ت ا ��3.� ا 3f%# � وإ)�*)� ا=> %ء. �� ا��.�ال ��ار� �h ھ5ه اf� .%��.i3+9 /� ا<,ت و�*ا�� �% أ)�% �f���م � ، �(*�(l��3.� ا %# �.��3 د ا .�#%3f � ا�� �%ة ��3 � إ h اf� � ا�� ��ارد ا � #%3f ا � � �3�%ج إ h ا�� ��اد p * ا<� � l#1%ء ا $%�� ? :�h ا��%ل #�% ، أو أن :�� � ا �r+�� /� و&�د #$q ا �? ا+�%ًs 8( t �: ظ%s3 ، +%ن ا 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(microsoft word 79-90\307\315\343\317 \346\322\355\344\310) al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 15, no. 4, december, (2019) p. p. 7990 improving the network lifetime in wireless sensor network for internet of thing applications ahmed a. salman* zainab t. alisa** *,**department of electrical engineering / college of engineering/ university of baghdad *email: ahmed_abdulhassan44@yahoo.com **email: zainab_alisa@yahoo.com (received 9 june 2019; accepted 9 september 2019) https://doi.org/10.22153/kej.2019.09.007 abstract mobile wireless sensor networks have acquired a great interest recently due to their capability to provide good solutions and low-priced in multiple fields. internet of things (iot) connects different technologies such as sensing, communication, networking, and cloud computing. it can be used in monitoring, health care and smart cities. the most suitable infrastructure for iot application is wireless sensor networks. one of the main defiance of wsns is the power limitation of the sensor node. clustering model is an actual way to eliminate the inspired power during the transmission of the sensed data to a central point called a base station (bs). in this paper, efficient clustering protocols are offered to prolong network lifetime. a kernel-based fuzzy c-means clustering algorithm (kfcm) is adopted to cluster sensor nodes, while a cluster head (ch) is selected for each cluster based on a fuzzy logic system. results depicts that the new work performs better than the existing algorithms (as low energy adaptive cluster hierarchy-mobile (leach-m) and low energy adaptive cluster hierarchy-mobile enhancement (leach-me)) in terms of network lifetime, energy consumption, packet transmission and stability period. keywords: iot, mobile wireless sensor network, kernel-based fuzzy c-means clustering algorithm (kfcm). 1. introduction iot is one of the common subjects currently. sensors and smart devices simplified the supplying of communication and information [1]. one of the iot aspects is the wireless sensor networks (wsn). the data is collected from all the sensors in a network characterized by low power consumption and a wide range of communication elements [2]. wsn encompasses number of nodes, whereas every node created by different parts such as sensors which are utilized to sense a physical parameter in an environment. the received analog signal can be converted to digital form by the analog to digital converter. the signal will be easily read and utilized by the processing element [3]. the sensing task is performed by individual nodes and consumed much energy that reduces the network lifetime. an increase in energy depletion and a decrease in the existence make sensor networks to be useless. also, other issues, processing ability, limited bandwidth, and memory of nodes can impact the network lifetime [4]. the future demand is sensor-based applications which will be requested in different domains of real-time scenarios such as observing the critical gases in industry, health care monitoring, air pollution monitoring and smartphones etc. the wsn yields a collection of sensor nodes organized over an application area and work together in synchronized form to observ and manage the environment and each node joins to other to form a network. the purpose of improving wsn is based on the military applications, mostly surveillance in conflict section [6]. by reason of the difficult jobs ahmed a. salman al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 7990 (2019) 80 in planning an energy effective network, many types of routing protocols have been planned. one of the suggested techniques, the hierarchical routing protocols which are also called clusterbased routing were content with the restrictions in wsns [5]. there are two-layer structure. one layer is included in the selection of the cluster head and the other layer is responsible for routing. the node in hierarchical routing that is responsible for accumulating data from different nodes in the cluster is called the cluster head (ch). it assembles all data from nodes and sends them to the base station. the cluster-based routing protocol is implemented in this paper. this protocol involves sequences with two stages in each round, the setup stage and the steady-state stage. in the setup stage, the kernel-based fuzzy c-means clustering algorithm (kfcm) is utilized via the base station to cluster the sensor nodes regularly. the twophase fuzzy logic method is used to select a notable node in the cluster as the head of the cluster. within the steady-state phase, the nodes sense the environment and then transmit the data to the base station. expanding network lifespan is a real hard task in mobile wireless sensor networks because sensors have restricted energy, where limited battery energy is one of the major constraints of mobile wireless sensor networks. the researchers have taken into consideration the clusterbased technique for data transmission to avoid the power exhaustion, leach [6], leach-m [7], leachme [8], enriched cluster established routing protocol for movable nodes in wsn ecbrmwsn [9], and cluster based routing (cbr) mobile [10] are mentioned as cluster-based energy-efficient protocols. in leach [6], the operation is divided into twostage, the setup stage and the steady-state stage. in the setup stage, chs are designated such that in the steady-state stage each node transmits its data to its own cluster head and then the ch collect the information received from the nodes that is owned by the same group and transmit them to the bs. one of the leach drawbacks is that it does not provide mobility. however, the leach-mobile protocol that supports the navigation has been introduced and is considered an improvement on the leach [7]. the ch choice has been developed by leach-m improved [8] (leach me). the sensor node that has the least mobility is selected as the cluster head. ecbr-mwsn [9] is a protocol wherein the cluster heads are chosen by means of the factors of maximum residual power, little mobility and tiniest distance from the base station. cbr-mobile [10] advocate the sensor nodes movability via using adaptively redistributing the timeslots in steps with sensor nodes movement. the ch selection in cbr-mobile, like leach-m, relies on the possibility model. in static wsn, there are many improvements on leach such as a stable improved leach (sileach) algorithm [11] which is proved to be highly efficient in terms of stability. an improvement on leach in terms of enhancing network life and reducing energy waste have been presented in [12]. another improvement has been suggested [13] on leach protocol in wireless sensor networks to diminish energy depletion and the transmissions to the base station by aggregating data. the rest of the paper describes the system model in section 2, simulation results in section 3, and finally the conclusion in section 4. 2. system model figure fig. 1 illustrates the proposed routing protocol. it involves number of rounds where each round has two phases; the steady-state and the setup phases. the cluster head collection and cluster construction are in the setup phase while the data is transferred at the steady-state phase as in figure fig. 2. 2.1 setup phase cluster head option and cluster forming are the main purposes of the setup phase. figure fig. 3 shows the setup phase algorithm where each block is described as follows. ahmed a. salman al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 7990 (2019) 81 fig. 1. contents of the mobile wsn protocol. fig. 2. timeline showing proposed protocol operation. fig. 3. flowchart of the setup phase. ahmed a. salman al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 7990 (2019) 82 2.1.1. initialization at the beginning, each sensor node sends the required information about its residual energy, the location and move count of the node. this information is sent as a “hi” message as shown in figure fig. 4. fig. 4. hi message details. 2.1.2. cluster formation the kernel-based fuzzy c-means clustering (kfcm) collects the sensor nodes. it interchanges the kernel-induced distance metric over the original euclidean distance. it enhances the precision with fewer error rate than in the fuzzy cmeans algorithm [14]; thus, it can decrease the iteration needed time for producing clusters considerably. this is very important in the formation of the clusters. to find the objective function in the fuzzy c-means algorithm, the following equation is used: �� (u, v)= ∑ ∑ ������ �� ‖ � � ��‖� …(1) where: c: is the number of clusters and designated as a specified value. n: is the number of nodes. �: is the coordinate of sensor node k. ���: is the membership of � in cluster i, satisfying∑ ��� � 1�� . m: is the quantity adjusting clustering fuzziness which is utilized to control nodes’ membership, m is usually equal 2 [15] �: is the set of cluster centres. the function �� is eliminated by known alternate iterative process. kfcm algorithm partitions k into c fuzzy separations by reducing the following cost function: ��(u, v)= 2 ∑ ∑ ������� ��� �1 � �� � ‚���� …(2) where �� �‚��� � exp ��‖ � � ��‖�/ơ�). the difference between the equations (1) and (2) is by changing the kernel-induced distance metric over the original euclidean distance [14]. minimizing equation (2) under the constraint of ���, we have: ���= " # #$%�&',)*�+ #,$# ∑ # #$%.&',)/01 #,$#2*$# …(3) ��= ∑ 3*'4'$# � 5�6',7*�8' ∑ 3*'4'$# � 5�6',7*� …(4) with kfcm algorithm, the cluster centroid is calculated as the average of all the sensor points measured by the cluster association gradation. repeatedly, upgrading the membership ��� by equation (3), ��� has the following conditions: ��� ∈ :0‚1<‚ ∀> � 1‚ … @‚ ∀a � 1‚ … b …(5) ∑ ��� � 1�� ‚ ∀> � 1‚ … @ …(6) 0 c ∑ ��� c d�� ‚ ∀a � 1‚ … b …(7) the iterative updating will stop either when ef ≤ ε where: ef= hi �� |���f � ���f� | ε: is the termination criterion in (0 ,1) range. t: is the iteration steps. sensor nodes are categorized to the clusters as stated by maximal degree of membership to generate regular spread clusters. if a k the sensor node has the highest degree of cluster affiliation i in t th execution, the sensor node k will join the cluster i, that is expressed as: af � k> ∶ ���f m ���∗ f opq irr a∗ � 1‚ … ‚b …(8) despite these communications (between nodes and the base station (bs)), if the nodes perform the operations instead of bs, the power consumptions will be much greater than when the bs perform those calculations. so for longer lifetime, case two has been adopted in this work. the process of finding the location of the node and placing it inside the cluster depends on the method of (kfcm). in this method, finding the location of a node and selecting the appropriate cluster for that node according to the membership level of each other nodes (this depends on the distance between the node and the centre of cluster) have been done in the bs so that the power consumption occurs in the base station. 2.1.3. calculation of mobility factor the mobility is one of the substantial factors that decides the head nodes. it is preferable to design a cluster head that does not move rapidly to stay away from frequent cluster head changes. the node may be separated from its cluster head and link a new one as the cluster head moves fast. this will lead to decrease the number of data packets exchanged between the cluster head and the node. therefore, bs, which is more robust than normal nodes, considers the mobility factor ahmed a. salman al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 7990 (2019) 83 in the proposed protocol and uses the fuzzy logic method to evaluate the mobility factor in an efficient way. mobility factor is evaluated by three parameters, these are relative mobility of the node according to its neighbours, velocity of the node, and transition count of the node. the lowermost mobility factor can be obtained with respect to lowest velocity, transition count, and relative mobility. the velocity (v) of the sensor node (vi), is computed as: s���� � t�6u�6u$#�vw�xu�xu$#�v ∆f …(9) where: ( f,zf), ( f� ,zf� ): are the coordinate status of node (vi) at the time t, t-1 respectively. ∆: is the interval time between t and t -1. the mobility metric (m) of a sensor node (vi) according to its neighbours is calculated by: [���� � ∑ \]*/�f��]*/�f� �\^_/`# ab … (10) where: c�d�e�: is the distance between neighbour (vj) and sensor node vi at time t. c�d�e � 1�: is the distance between vj and sensor node vi at time t-1. neis the amount of sensor node neighbour’s vi. as a hi-message, the amount of transitions from one cluster to another during the past five rounds will be directed to the bs from the sensor node. this assessment relies on the amount of times the node transitions. the concept of fuzzy logic is created primarily through four steps: fuzzification, rule evaluation, aggregation, and defuzzification. it can be used for mobility factor due to the simplicity of the mamdani fuzzy inference technique computation. to calculate the mobility factor, four steps are needed to be used within the fuzzy inference system (fis) as follows: the inputs to the fuzzification step shown in figure fig. 5 are the transition count of the node, relatve mobilty of the node with respect to its neighbours, and the velocity of the node. their membership functions can be shown in figure fig. 6. fig. 5. mobility factor calculation (a) velocity of the node (b) relative mobility (c) transition count fig. 6. functions for fuzzification (a, b, c) ahmed a. salman al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 7990 (2019) 84 then the membership values are supplied to if-then rules as illustrated in table 1. an (or) operation selects the maximum rule calculation values to produce the new fuzzy sets, which are the input to the defuzzification stage. the centre of gravity (cog) technique is used to compute the chance rate for each sensor node to be a cluster head [16]: fgh � ∑ 6*ijk�6*�l*`#∑ jk�6*�l*`# …(11) where m: is described as the amount of output sample values, �: is defined as value of the output element no� ��: is the score of a membership function of fuzzy set a. the fuzzy sets for the output variable are show in figure fig. 7. fig. 7. mobility factor. 2.1.4. cluster head and the backup clus head selection cluster head is elected using a two-phase fuzzy approach when pointing the clusters. the bs calculates the opportunity for all nodes. figure fig. 8 displays the offered model for fuzzy based ch appointment. fig. 8. two phase fuzzy logic system for cluster head election. a radio model is used in this paper and the following equations explain its mathematical model. to conduct an l-bit data at a distance d, a node employs the energy as: ep8��‚c� � q� ebrb� s � ∈tu c� ao c c cv � ebrb� s � ∈�w cx ao c m cv …(12) where cv � y ∈zl ∈,{ …(13) • ebrb� : defines energy expended to run the electronic circuits. • ∈tu and ∈�w : represents the transmitter amplifier characteristics. • d: describes the gap between the two ends of the communication. • �: is data packet size. the dissipated energy to receive a k-bit packet is e|8��� � � ebrb� …(14) in addition to above, the cluster head also goes to waste the energy due to data collection. in the first phase, the inputs are energy and mobility factor of the node and the output is first chance. the second phase of the fuzzy logic system for cluster head election has three input parameters: first-chance from the first phase, closeness to bs and node expected efficiency. node probable efficiency [17] is the quotient between probable residual energy (the remains energy of node after attaining its function such as head of cluster for a round) and the predictable average energy of the cluster. to compute the probable average energy of cluster, the predictable spent energy of node is determining to be a cluster head (ch) and the expected expended energy of the nonch nodes as: the predictable consumed energy is given as: e}~� �v�u3�b] (r, cfv ��, n) = dt���b* ( e p� (r, cfv ��) + n*( e |� (r) + r * e�o)) … (15) then the probable remaining energy of node to be a ch after a steady-state phase could be given as: e��}~� |bu�]3�r (r, cfv ��, n) = e�bu�]3�r e}~� �v�u3�b] …(16) the likely spent energy of non-ch node could be demonstrated after steady-state phase via: e�v����}~� �v�u3�b] (r, cfv��) = dt���b* ( e p� (r, cfv ��)) …(17) then the estimated residual energy of non-ch node next steady-state phase is: eb6w|bu�]3�r (r, cfv��) = e�bu�]3�r e�v����}~� �v�u3�b] …(18) ahmed a. salman al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 7990 (2019) 85 after the steady-state phase, the expected residual energy of cluster can be obtained consequently as follows: e�r3ufb��bu�]�3r = e��}~� |bu�]3�r + ( a 5) e�v����}~� �bu�]3�r …(19) where: cfv ��: represents the distance between a ch and the bs. e�o: describes the aggregation operation and it is constant. e�bu�]3�r: is the residual energy of node before ch choice. n: symbolizes the number of cluster members. r : is the size sensed packet. n: represents the number of nodes spread in the network field. �: is the number of clusters at each round. 2.1.5. advertisement, acknowledgment, tdma scheduling the ch broadcast an announcement message to the sensor nodes in its cluster (members of cluster). the node directs an acknowledgment message to inform this ch that it belongs to it. then the ch creates a tdma schedule and announces it to the members of the cluster. if sensor nodes do not receive data request packet from cluster head because of the dead of both the cluster head and backup cluster head, then sensor nodes send join_request to the nearby cluster heads. 2.2. steady-state phase the steady-state stage involves the number of frames and the data transmission occurred in each frame, and this occurs in each round. after the end of one frame and so on, another frame begins. the steady-state stage is finished and another round begins after the end of the last frame with a new setup stage and a steady-state stage. figure fig. 9 shows the flowchart of one frame. 3. simulation results this paper presents an improved effective routing protocol in autonomic wireless sensor networks for iot applications. the adopted application is a system follows the movements of doctors inside the hospital to be called in urgent cases and the possibility of reaching them easily. figure fig. 10 shows the city of medicine in baghdad and the red marks indicate where doctors are located. when the doctors (sensors) have been moved, the doctor's site is transferred to the base station and the base station will transmit the information to the internet to be viewed from any department within the hospital. the mobility model for sensors is a random waypoint model table 2. table 1, fuzzy rule base. the movement of sensors (doctors) can be shown in figure fig. 12. the parameters used in matlab simulation for the network model are described in table 2. the environment has been adopted in this work consist of 100 nodes distributed evenly within a 100m×100m region so as to compare the execution of the planned clustering algorithms with leach-m, leachme protocols in terms of network lifetime, average energy dissipation, successful packets delivery, and number of times ch fails in transmission. figures fig. 13-16 show the s= slow f= fast w= weak m= medium h= high v= very l= low st= strong li= little rule no. velocity relative mobility transitio n count mobility factor 1 s s l v w 2 s s m w 3 s s h li w 4 s m l w 5 s m m li w 6 s m h li m 7 s f l li w 8 s f m li m 9 s f h m 10 m s l li w 11 m s m li m 12 m s h m 13 m m l li m 14 m m m m 15 m m h h m 16 m f l m 17 m f m h m 18 m f h li st 19 f s l m 20 f s m h m 21 f s h li st 22 f m l h m 23 f m m li st 24 f m h st 25 f f l li st 26 f f m st 27 f f h v st ahmed a. salman al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 7990 (2019) 86 evaluated results. the stability period (first node dies) is evaluated with different number of sensors as shown in figure fig.17. then, it is measured with the adjustment of bs as in figure fig. 18. finally, number of packets transmitted is measured when static sensors are used in addition to mobile sensors as illustrated figure fig. 19. fig. 9. flowchart of one frame of steady-state phase fig. 10. movement of doctors within the city of medicine (a) clusters and cluster head at round 48 (b) clusters and cluster head at round105 ahmed a. salman al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 7990 (2019) 87 (c) clusters and cluster head at round 157 (d) clusters and cluster head at round 268 fig. 11. clusters and cluster heads at different rounds fig. 12. movement of doctors within the city of medicine after clusters and cluster head selection. table 2, network details parameter value network size 100m i 100m node number (n) (50), (100), (150), (200), (250) position of the base station [50, 50], [50,100], [50,150], [50,200], [50,250 initial energy (eo) 0.5 joule hi packet size 129 bits data packet size 6400 bits frames number 18 optimum cluster number (copt) 5 eelec 50 nj/bit e_thr 0.001 joule ∈�� 10 pj/bit/h� ∈�� 0.0013 pj/bit/hx eda 5 nj/bit/packet sensor speed [0,10] m/s mobility model random waypoint fig. 13. dead nodes’ number against rounds’ number. fig. 14. mean energy waste in each round ahmed a. salman al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 7990 (2019) 88 fig. 15. total number of transmitted packets versus round number. fig. 16. number of moments ch flops in transmission against the number of rounds. fig. 17. stability period subject to different number of nodes. fig. 18. stability period with varying position of bs fig. 19. the packets’ number transmitted effectively versus number of mobile sensor nodes the comparison between the proposed protocols with other work [18] can be shown in table 3 in terms of the round number when the first node expires and the successful number of sent packets. table 3, a comparison with other work 4. conclusion routing protocols that provide motion of sensor nodes have been designed and improved by researchers like the mobile wireless sensor networks. they propose a good solution in many fields especially in iot fields. in this paper, an algorithm is proposed to improve the routing protocol by increasing the number of transmitted packets. in this way, the kernel-based fuzzy cmeans clustering algorithm (kfcm) and a twophase fuzzy logic methodology for ch determination are used to build a technique based on gathering the nodes into clusters. simulation results showed an enhancement in the network lifetime, packet transmission, stability period, and energy consumption as to leach-m and leach-me schemes. protocol first node dies successful send packets proposed 59 127200 [18] 34 100649 ahmed a. salman al-khwarizmi 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[12] salem, a.o.a. and shudifat, "enhanced leach protocol for increasing a lifetime of wsns," personal and ubiquitous computing, pp.1-7, 2019. [13] h. kumar, vp chahal, and p. raj "improvement on leach protocol in wireless sensor networks, " international journal of computer applications, vol.97, no.21, pp1-4, 2019. [14] d. vanisri, "a novel kernel based fuzzy c means clustering with cluster validity measures, " international journal of computer science and network solutions, vol.3, no.12, pp.254-260, 2014. [15] j. c. bezdek, " fcm: the fuzzy c-means clustering algorithm, " computers & geosciences, vol.10, no. 2-3, pp.191-203, 1984. [16] m. negnevitsky, " artificial intelligence: a guide to intelligent systems, " pearson education, 2nd edition, 2005. [17] alami, hassan el and a. najid. "energyefficient fuzzy logic cluster head selection in wireless sensor networks, " international conference on information technology for organizations development (it4od). ieee, pp. 1-7, 2016. [18] z. t. alisa and h. nassrullah, " minimizing energy consumption in wireless sensor networks using modified genetic algorithm and an energy balance filter, " alsadeq international conference on multidisciplinary in it and communication science and applications (aic-mitcsa). ieee, pp. 1-6, 2016. )2019( 7990، صفحة 4العدد ، 15دجلة الخوارزمي الهندسية المجلم احمد عبد الحسن سلمان 90 تحسين عمر الشبكة في شبكة االستشعار الالسلكية لتطبيقات انترنيت االشياء زينب توفيق باقر** عبد الحسن سلمان* احمد قسم الهندسة الكهربائية / كلية الهندسة / جامعة بغداد ،*** yahoo.com44ahmed_abdulhassan@*البريد االلكتروني: zainab_alisa@yahoo.com** البريد االلكتروني: الخالصة جموعة مر منخفضة في وبأسعا اكتسبت شبكات االستشعار الالسلكية المتنقلة اهتماًما كبيًرا في السنوات األخيرة نظًرا لقدرتها على توفير حلول جيدة ي فدامه خكما يمكن استية.متنوعة من المجاالت. يقوم (انترنيت االشياء) بتوصيل تقنيات مختلفة مثل االستشعار والتواصل والشبكات والحوسبة السحاب يسة لـ شبكات لتحديات الرئية. أحد االبنية التحتية األنسب لتطبيق إنترنت األشياء هي شبكات االستشعار الالسلكان المراقبة والرعاية الصحية والمدن الذكية. إلى نقطة ات المستشعرةل البيانلتقليل الطاقة المستهلكة أثناء نقاالستشعار الالسلكيه هو الحد من طاقة عقدة االستشعار. نموذج التجميع هو وسيلة فعالة بنية على ية التجميع المفي هذا العمل ، يُقترح بروتوكوالت تجميع فعالة إلطالة عمر الشبكة. يتم اعتماد خوارزم .(bs) مركزية تسمى المحطة األساس تم تحسين لكل مجموعة بناًء على نظام منطق غامض. (ch) ار رأس مجموعةلتجميع عقد المستشعر ، بينما يتم اختي (kfcm) النواة c أساس شبكة العقد في ال ون جميعبروتوكول التوجيه المقترح من سيناريو ثابت إلى سيناريو جوال لمواجهة التحدي المتمثل في معالجة تأثر المجموعه عندما تك مر مجموعة ، يستج من الحتياطي لحماية النظام بحيث في حالة فشل راس المجموعة أو الخروتم اقتراح نهج يسمى رأس المجموعة البديل او االوتتحرك. من حيث leach-me و leach-m النظام يعمل بكفاءة. توضح نتائج المحاكاة أن البروتوكول المقترح يعمل بشكل أفضل من األعمال السابقة مثل قرار.االست مدةعمر الشبكة واستهالك الطاقة ونقل الرزم و 8484 al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 4, no. 2, pp 83-97 (2008) نسبٍكت (tig spot) يحاكاة انخىصٌغ انحشاسي نىطالث انهحاو انُمطً يغٍُسٍىو باسخؼًال طشٌمت انؼُاطش انًحذدةانًٍُىو احالو ػبذ االيٍش.و.ػبذ انحسٍٍ غاَى انًانكً و. د.يُى خضٍش ػباط ا. د.و.ا لغُ اٌرؼ١ٍُ اٌرىٌٕٛٛظٟ لغُ اٌرؼ١ٍُ اٌرىٌٕٛٛظٟ لغُ ٕ٘ذعح ا٤ٔراض ٚاٌّؼادْ اٌؼشاق–تغذاد / اٌعاِؼح اٌرىٌٕٛٛظ١ح (received 29 may 2007; accepted 22 january 2008) انخالطت ٠رٕاٚي ٘زا اٌثؽس ذؽ١ًٍ ِٚؽاواج اٌرٛص٠غ اٌؽشاسٞ ٌٛطالخ اٌٍؽاَ إٌمطٟ تطش٠مح اٌمٛط اٌىٙشتائٟ تمطة اٌرٕىغرٓ اٌّؽّٟ تاٌغاص tig))اٌخاًِ spotَِٛغ١ٕغ١َٛ ٔٛعٌغث١ىح ا١ٌّٕ٤ (5052-o)خالي اعرخذاَ طش٠مح اٌؼٕاطش اٌّؽذدج ِٓ (finite element method) صِٓ اٌٍؽاَ ٚطٛي اٌمٛط فٟ اٌرٛص٠غ اٌؽشاسٞ ٚو١ّح , ِٚؼشفح ذأش١ش ِرغ١شاخ اٌٍؽاَ ِٓ ذ١اس اٌٍؽاَ (ansys-5.4)تاعرخذاَ تشٔاِط ا٤تؼاد ٌّؼشفح اٌرٛص٠غ اٌؽشاسٞ فٟ تشوح اٌٍؽاَ اٌذائش٠ح (d-3) ذُ تٕاء أّٔٛرض اٌؼٕاطش اٌّؽذدج شالشٟ. اٌؽشاسج اٌذاخٍح فٟ ِٕطمح اٌٍؽاَ اٌّؼذْ إٌّظٙش داخً ِٕطمح اٌٍؽاَ ِٓ خالي اٌظف١ؽح اٌؼ١ٍا ػثش اٌغطػ اٌفاطً اٌٝ اٌظف١ؽح اٌغفٍٝ (ػّك اٌٍؽاَ)ِالؼظح ِمذاس ذغٍغً ٚ ِٕطمح اٌٍؽاَ ) ِٕاطك اٌٍؽاَ اٌّخرٍفح ٚل١ّٙا فٟ ٚسعّد اٌؼاللاخ اٌرٟ ذث١ٓ ذٛص٠غ دسظاخ اٌؽشاسج .(spot weld)ِىٛٔح ٔمطح اٌٍؽاَ ((. (hazٚإٌّطمح اٌّرأششج تاٌؽشاسج أٚضؽد إٌرائط إٌٝ أْ ِٕطمح اٌٍؽاَ ٚإٌّطمح اٌّرأششج تاٌؽشاسج ذرؼشع إٌٝ أؽذاس ٚذثا٠ٓ وث١ش٠ٓ فٟ دسظاخ اٌؽشاسج تغثة اٌذٚسج c°698) )ؼ١س ٚطٍد أػٍٝ ل١ّح ٌذسظح اٌؽشاسج ٌٍّؼذْ إٌّظٙش فٟ ٔمطح اٌٍؽاَ إٌٝ , اٌؽشاس٠ح اٌشذ٠ذج ٔر١عح ٌؼ١ٍّرٟ اٌرغخ١ٓ ٚاٌرثش٠ذ . أخفضد تاذعاٖ اٌّؼذْ ا٤عاط اٌثؼ١ذ ػٓ ِٕطمح اٌٍؽاَ شُ (1.6mm)ٚطٛي لٛط (130a)ٚذ١اس ٌؽاَ (6sec)ٌؽاَ صِٓ ذمش٠ثا ػٕذ نًمذيتا. 1 tig))انهحاو انُمطً بمطب انخُكسخٍ انًحًً بانغاص انخايم spot ٚ٘ٛ اٌٍؽاَ اٌزٞ ٠رُ ت١ٓ ظضئ١ٓ ِؼذ١١ٔٓ ِرشاوث١ٓ (overlapping) ِٓ إر ٠ثذا االٔذِاض ٚذغٍغً اٌّؼذْ إٌّظٙش ػثش اٌغطػ اٌفاطً ٚطٛال ٌٍظف١ؽح اٌؼ٠ٍٛحاٌغطػ اٌخاسظٟ ٌٍظف١ؽح اٌغف١ٍح ِىٛٔح ٚطٍح اٚ ٔمطح اٌٍؽاَ إٌٝ اٌغطػ اٌذاخٍٟ (weld spot ِ ) ٛٚتذْٚ أعرخذاَ ِؼذْ ؼش(filler metal ,) ٠ّٚىٓ إْ ٠ىْٛ ِٓ ظٙح ٚاؼذج اٚ ِٓ ظٙر١ٓ ٠ٚىْٛ اٌشىً اٌؼاَ . 2,1] [ ٌّٕطمح اٌٍؽاَ ِماستا إٌٝ شىً اٌذائشج اٌرٕىغرٓ ِصثد داخً ِٓ ٠رُ فٟ ٘زٖ اٌطش٠مح اعرؼّاي لطة ِشؼً اٌٍؽاَ ٠ّٚصً أؼذ ألطاب اٌذائشج اٌىٙشتائ١ح ت١ّٕا ذّصً اٌمطة ا٢خش, إر أْ اٌمٛط ٠رٌٛذ (ٌحؽاٌش)االظضاء اٌّشاد ٌؽاِٙا ِا ت١ٓ لطة اٌرٕىغرٓ ٚاٌمطؼح اٌّشاد ٌؽاِٙا, ٠ٚىْٛ لطة اٌرٕىغرٓ غ١ش لاتً ٌالعرٙالن ٌٚىٓ ٠ّىٓ اعرثذاٌٗ ؼغة ٔٛع . [1]ي اٌر١اس اٌّغرؼُ ِٚمذاس ٚٔٛعٖاٌّؼذْ اٌّشاد ٌؽاَ .(tig spot)٠ّصً ِثذأ ػ١ٍّح اٌٍؽاَ تطش٠مح (1)ٚاٌشىً إْ ػ١ٍّح اٌٍؽاَ ذؼرّذ أعاعا ػٍٝ اٌّظذس اٌؽشاسٞ اٌّغرؼًّ فٟ سفغ دسظح ؼشاسج اٌّؼذْ إٌٝ دسظح ؼشاسج اٌٍؽاَ, ٟٚ٘ تزٌه ذؼًّ ػٍٝ ذغخ١ٓ ِٕطمح اٌٍؽاَ إٌٝ دسظح االٔظٙاس اسٞ, ِّا ٠ؤدٞ إٌٝ ؼذٚز اظٙاداخ ٖفٟ ؼاٌح اٌٍؽاَ ا٤ٔض ؼشاس٠ح فٟ ا٤ظضاء اٌٍّؽِٛح ٔر١عح ٌٍرغخ١ٓ اٌّٛلؼٟ ٌرٍه أٞ ِٓ )ا٤ظضاء تاٌراٌٟ فئْ إٌّاطك اٌمش٠ثح ِٓ ِٕطمح اٌٍؽاَ ذغخٓ إٌٝ دسظاخ (اٌّظذس اٌؽشاسٞ ٚ٘ٛ اٌمٛط اٌىٙشتائٟ ؼشاسج ػا١ٌح ٌزٌه ذرّذد أوصش ِٓ إٌّاطك اٌثؼ١ذج ػٓ ِٕطمح ٚوزٌه ذرؼشع ا٤ظضاء اٌؼ١ٍا ِٓ اٌٍّؽِٛح إٌٝ دسظاخ .اٌٍؽاَ ؼشاسج أوصش ِٓ ا٤ظضاء اٌغفٍٝ ِّا ٠ؤدٞ إٌٝ ذشٖٛ اٌٍّؽِٛح اٌمطغ ذثش٠ذ ٚال ذخرفٟ االظٙاداخ اٌؽشاس٠ح ػٕذ اِغثثح ذشى١ال ٌذْ االترذائ١ح ٌٍظفائػ ِّا ٠غثة اٌؽشاس٠ح إٌٝ اٌذسظحاٌٍّؽِٛح [. 3]اظٙاداخ ؼشاس٠ح ِرثم١ح ٚلذ أظش٠د دساعاخ ٚتؽٛز ػذ٠ذج ؼٛي ِؽاواج ػ١ٍّح ِٓ ]justin d4 [اٌٍؽاَ ِٕٚٙا اٌذساعح اٌرٟ لاَ تٙا اٌثاؼس ظاِؼح فشظ١ٕ١ا ٚاٌزٞ ذٕاٚي فٟ تؽصٗ ِؽاواج ػ١ٍّح اٌٍؽاَ -2519)ٌٛطالخ ٌؽاَ ذٕاوث١ح ٚصا٠ٚح ِٓ عث١ىح اال١ٌَّٕٛ t87) ٚأعرخذَ اٌثاؼس طش٠مح . 2319تاعرؼّاي ِؼذْ ؼشٛ ٔٛع اٌؼٕاطش اٌّؽذدج تاعرؼّاي ِٛد٠ً شالشٟ ا٤تؼاد فٟ اٌرؽ١ًٍ اٌؽشاسٞ ٚا١ٌّىا١ٔىٟ ٌٛطٍح اٌٍؽاَ تاالػرّاد ػٍٝ خٛاص اٌّادج ٚلذ ؼظً ػٍٝ ػذج ػاللاخ ت١ٓ . (خٛاص اٌّشٚٔح ٚاٌٍذٚٔح) . دسظح اٌؽشاسج ٚاٌخٛاص ا١ٌّىا١ٔى١ح ٚاٌف١ض٠ا٠ٚح تّؽاواج ػ١ٍّح ]daniel berglund ]5 ٚلاَ اٌثاؼس ( gtaw)اٌٍؽاَ تطش٠مح اٌمٛط اٌىٙشتائٟ تمطة اٌرٕىغرٓ ٚاالظٙاداخ اٌّرثم١ح فٟ االظضاء اٌىث١شج ٚاٌّؼمذج اٌشىً ِٓ عثائه اال١ٌَّٕٛ راخ اٌّماِٚح اٌؼا١ٌح ٚاٌرٟ ذذخً فٟ طٕاػح اٌطائشاخ ٚأعرخذَ اٌثاؼس طش٠مح اٌؼٕاطش اٌّؽذدج فٟ ِؽاواج . ٚاٌظٛاس٠خ . اٌرظ١ٕغ ٚذط٠ٛشوفاءج ِصً ٘زٖ ا٤ظضاء اٌّّٙح 98-84، الصفحة 2، العدد 4 مجلة الخوارزمي الهندسية، المجلد منى خضير عباس . د (2008) 84 هذف انبحث ذؽ١ًٍ ِٚؽاواج ػ١ٍّح اٌٍؽاَ إٌمطٟ تطش٠مح اٌمٛط -1 tig)اٌىٙشتائٟ تمطة اٌرٕىغرٓ اٌّؽّٟ تاٌغاص اٌخاًِ spot)َِٛغ١ٕغ١َٛ ٌغث١ىح ا١ٌّٕ((al-mg خالي ِٓ ansys) تشٔاِط تاعرخذاَاعرخذاَ طش٠مح اٌؼٕاطش اٌّؽذدج تٕاء أّٔٛرض شالشٟ االتؼاد ٌّؼشفح اٌرٛص٠غ اٌؽشاسٞ ٚ (5.4 فٟ ٔمطح اٌٍؽاَ ٚ ذؽذ٠ذ دسظاخ اٌؽشاسج ٌّٕطمح اٌٍؽاَ .ٚإٌّطمح اٌّرأششج تاٌؽشاسج صِٓ )دساعح ذأش١ش ِرغ١شاخ اٌٍؽاَ إٌمطٟ االٔظٙاسٞ ِٓ -2 لطش ٔمطح اٌٍؽاَ ٚػّك فٟ (ٚذ١اس اٌٍؽاَ ٚطٛي لٛط اٌٍؽاَ فٟ ِٕطمح اٌٍؽاَ ػثش اٌعضء٠ٓ إٌّظٙشأٚذغٍغً اٌّؼذْ . اٌّرشاوث١ٓ ِماسٔح إٌرائط إٌظش٠ح اٌّغرؽظٍح ِٓ اٌثشٔاِط ِغ إٌرائط -3 اٌؼ١ٍّح ِٓ ٔاؼ١ح ل١اط لطشٔمطح اٌٍؽاَ ٚػّك اٌرغٍغً .ٌّٕطمح اٌٍؽاَ ػثش اٌّمطغ اٌؼشضٟ ٌٛطٍح اٌٍؽاَ إٌمطٟ انداَب انُظشي. 2 assumptions انفشضٍاث ٌغشع اٌرٛطً اٌٝ اٌّؼادالخ اٌرفاض١ٍح اٌخاطح تأرماي اٌؽشاسج ِٚؼشفح ذٛص٠غ دسظاخ اٌؽشاسج فٟ ٚطٍح اٌٍؽاَ إٌمطٟ (tig spot) َِٛغ١ٕغ١َٛ ٌٍعضء٠ٓ اٌّرشاوث١ٓ ِٓ عث١ىح اال١ٌّٕ (o-5052) ذُ أعرخذاَ اٌفشض١اخ اٌرا١ٌح : شاترح ال ذرغ١ش ِغ دسظح (ٌٍغث١ىح)اٌخٛاص اٌف١ض٠ا٠ٚح ٌٍّؼذْ -1 . اٌؽشاسج ٚاْ أرماي اٌؽشاسج (z ,y ,x)اٌذساعح ذأخز شالز اتؼاد -2 .٠ىْٛ ِرغاٚٞ فٟ االذعا٘اخ اٌصالشح واْ اال٘رّاَ ٠ٕظة ػٍٝ صِٓ اٌٍؽاَ ِغ دسظح اٌؽشاسج -3 . ١ٌٚظ اٌرٛص٠غ اٌؽشاسٞ ٌٍٛطٍح ِغ اٌضِٓ أٞ اْ اٌعضء اال٠ّٓ ِٓ ((٠yzّش ِغرٛٞ اٌرٕاظش تاٌّغرٛٞ -4 . ٠ٕاظش اٌعضء اال٠غش (ٚطٍح اٌٍؽاَ)اٌعغُ .٠رُ أّ٘اي أٔرماي اٌؽشاسج تاٌؽًّ ٚاالشؼاع -5 انخطىاث انشئٍست نطشٌمت انؼُاطش انًحذدة إْ ذٕف١ز طش٠مح اٌؼٕاطش اٌّؽذدج ٠ّش تخطٛاخ سئ١غ١ح ذرُ : وّا ٠أذٟ حكىٌٍ أًَىرج انؼُاطش انًحذدة ذّصً اٌخطٛج ا٤ٌٚٝ ِٓ ِشاؼً اٌرؽ١ًٍ تاٌؼٕاطش اٌّؽذدج, ؼ١س ٠رُ تٕاء أّٔٛرض اٌؼٕاطش اٌّؽذدج تاعرثذاي إٌّظِٛح اٌؽم١م١ح تأّٔٛرض ٠رأٌف ِٓ ِعّٛػح ِٓ اٌؼٕاطش ِشذثطح ف١ّا ت١ٕٙا تاٌؼمذ ٚإْ ػذد اٌؼٕاطش فٟ ا٤ّٔٛرض ٚٔٛػٙا ٠ؼرّذ ػٍٝ اٌخٛاص اٌف١ض٠ا٠ٚح ٚشىً اٌؼٕظش ٚاٌظشٚف اٌؽذ٠ح ٌٍّغاٌح اٌّشاد [. 6]دساعرٙا shape functionاخخٍاس دوال انخمشٌب ذرُ فٟ ٘زٖ اٌخطٛج ذؽذ٠ذ ػاللاخ ٌرمش٠ة اٌؽً ٌىً ػٕظش ٚ٘زٖ اٌذاٌح ذظف اٌؼاللح . ِٓ خالي اخر١اس داٌح ِٕاعثح ٌٍؼٕظش ِغ إؼذاش١اخ اٌؼمذ اٌرٟ ذشتظ ت١ٓ ِرغ١شاخ إٌّظِٛح اٌؽم١م١ح pynomical)ٚٔٛع ٘زٖ اٌذاٌح ٟ٘ دٚاي ِرؼذدج اٌؽذٚد.اٌؼٕاطش function) إضافح إٌٝ إِىا١ٔح ص٠ادج دسظح دلح اٌؽً ِٓ خالي . ] 6]ص٠ادج دسظح ؼذٚد اٌذاٌح derivation of اشخماق يظفىفت اندساءة ويخده انحًم stiffness matrixaial (f) ِٚرعٗ اٌؽًّ (k)ذرُ ػ١ٍّح اشرماق ِظفٛفح اٌعغاءج تاعرخذاَ ششٚط اٌرٛاصْ ٌىً ػٕظش خالي أّٔٛرض ا٦صاؼاخ . 7]]ٚدسظاخ اٌؽشاسج [k].δ=f ...(1) [k].t=q …(2) assembly the حدًٍغ يظفىفت اندساءة نهؼُظش ونهحًم stiffness element matrix and load vector فٟ ٘زٖ اٌخطٛج ٠رُ ذع١ّغ ِظفٛفح اٌعغاءج ِٚرعٗ اٌؽًّ ٌىً ػٕظش ٌٍؽظٛي ػٍٝ ِظفٛفح اٌعغاءج اٌى١ٍح ِٚرعٗ اٌؽًّ .7]]اٌىٍٟ ٥ٌّٔٛرض equilibrium equation إٌداد يؼادنت انخىاصٌ ٠رُ إ٠عاد ِؼادٌح اٌرٛاصْ تإٌغثح ٌالصاؼاخ ٚرٌه ترطث١ك ٔظش٠ح ( minimum total potential energy)اٌطالح اٌىإِح اٌذ١ٔا ٚاٌرٟ ذٕض ػٍٝ أْ طالح االٔفؼاي ٔالض اٌشغً اٌّغٍظ ٠عة أْ [8]٠ىْٛ ألً ِا ٠ّىٓ x=u-w …(3) 0 x    …(4) : ؼ١س أْ u : طالح االٔفؼاي strain energy w : ًاٌشغwork done x : اٌطالح اٌىإِح potential energy        dvolbdbk te   )( ...(5)   fk   ...(6) أِا فٟ ؼاٌح دسظاخ اٌؽشاسج فمذ ذُ اعرؽظاي ِؼادٌح اٌرٛاصْ ِٓ اٌؼاللح اٌؼاِح ٌٍرٛط١ً اٌؽشاسٞ t t q z t zy t yx t x c kkk p zyx                                   …(7) phase) ٦ظٙاس ذغ١ش اٌطٛسcpؼ١س ذُ إدخاي ذأش١ش change) اٌّؽذدج ٠ٕرط اٌؼٕاطشتطش٠مح (7) ٌّؼاٌعح اٌّؼادٌح :اٌّؼادٌح اٌرا١ٌح          the f t t ctk …(8) :ؼ١س أْ f th ِظفٛفح أؼاد٠ح اٌؽًّ اٌؽشاسٞ :  c : ذأش١شاخ )ِظفٛفح اٌىرٍح ذّصً ذأش١ش اٌؽاٌح ا٤ٔرما١ٌح (اٌضِٓ  ke : ِٞظفٛفح اٌرٛط١ً اٌؽشاس t = دسظح اٌؽشاسج(c º ) = t ِٓاٌض((sec = ρ وصافح اٌّادج (kg/m 3 ) =cpاٌؽشاسج إٌٛػ١ح ٌٍّادج (j/kg.k) =q ُاٌؽشاسج اٌّرٌٛذج ٌٛؼذج اٌؽع (j/m 3 ) =kاٌّٛط١ٍ١ح اٌؽشاس٠ح (w/m. cº) =qو١ّح اٌؽشاسج إٌّرمٍح ٌٛؼذج اٌّغاؼح ( 2 w/m ) =h ٞاٌّؽرٜٛ اٌؽشاس ( ٟاالٔصاٌثkj/kg ) =hًِّؼاًِ أٔرماي اٌؽشاسج تاٌؽ (w/m 2 . cº) (w/m. k) ِؼاًِ اٌرٛط١ً اٌؽشاسٞ = ג n= ِرعٙٗ ٚؼذج ػّٛد ػٍٝ اٌغطػ =ti اٌذسظح اٌؽشاس٠ح ا٤ترذائ١ح ((cº 98-84، الصفحة 2، العدد 4 مجلة الخوارزمي الهندسية، المجلد منى خضير عباس . د (2008) 85 kz,ky,kx = اٌّٛط١ٍح اٌؽشاس٠ح فٟ االذعا٘اخz,y,x ٍٝػ اٌرؼالة ansys)كٍفٍت بُاء األًَىرج انخحهٍهً باسخخذاو بشَايح . 3 5.4) انسبٍكت انًسخؼًهت ذُ فٟ ٘زا اٌثؽس إظشاء ِؽاواج ػ١ٍّح ٌؽاَ اٌمٛط اٌىٙشتائٟ ( tig spot)إٌمطٟ تمطة اٌرٕىغرٓ اٌّؽّٟ تاٌغاص اٌخاِـــً غ١ش اٌماتٍح ٌٍرؼاًِ (o-5052 )ِغ١ٕغ١َٛ -ٌغث١ىــــح ا١ٌّٕ٤َٛ ٠ٚؼضٜ . اٌؽشاسٞ ؼغة ذظ١ٕف اٌعّؼ١ح ا٤ِش٠ى١ح ١ٌّٕ٥ٌَٛ ِغ١ٕغ١َٛ العرخذاِاذٙا اٌٛاعؼح فٟ -اخرثاس عث١ىح ا١ٌّٕ٤َٛ اٌّعاالخ اٌظٕاػ١ح إضافح إٌٝ وٛٔٙا أوصش أٔٛاع عثائه ا١ٌّٕ٤َٛ .[8] اعرؼّاالً وأظضاء ٍِؽِٛح ٠ٛضػ اٌرشو١ة اٌى١ّ١اٚٞ ٌٍغث١ىح اٌّغرؼٍّح (1)ٚاٌعذٚي ٠ٛضػ اٌخٛاص ا١ٌّىا١ٔى١ح ػٕذ دسظح (3) ٚ(2)ٚاٌعذٚالْ -o )(al-mg)ؼشاسج اٌغشفح ٚاٌخٛاص اٌؽشاس٠ح ٌغث١ىــح ٠ٛضػ أتؼاد اٌمطغ اٌّشاد (2)ٚاٌشىً , [9]ػٍٝ اٌرؼالة (5052 ٌؽاِّٙا (ansys 5.4)ًَزخت ػًهٍت انهحاو باسخخذاو بشَايح انـ -:ٚذشًّ اٌخطٛاخ اٌرا١ٌح .prep 7اٌشعُ تٛاعطح اٌؼثاسج -1 -3) سعُ اٌمطؼر١ٓ اٌّشاد ٌؽاِّٙا فٟ ؼاٌح واٍِح ا٤تؼاد -أ dimensions .) ٌّا وأد ا٤ظضاء اٌّشاد ٌؽاِّٙا ِرٕاظشج اٌّماطغ, فمذ ذُ ب .أخز ٔظف ا٤ّٔٛرض ٌرٛض١ػ ذٛص٠غ دسظاخ اٌؽشاسج ٠ٛضػ اٌششٚط اٌؽذ٠ح اٌخاطح ٌرصث١د (3)ٚاٌشىً (. overlap pieces)اٌمطؼر١ٓ اٌّرشاوثر١ٓ سعُ اٌمطؼر١ٓ فٟ ؼاٌح ٔظف ِمطغ ٚوّا ِٛضػ فٟ شىً ض : ٚذُ اٌشعُ ؼغة ا٤تؼاد ا٢ذ١ح.(4) length(l)=100mm, width(b)=12.5mm, thickness(t)=1mm, اٌّشؼٍح اٌصا١ٔح إدخاي اٌخٛاص ا١ٌّىا١ٔى١ح ٌغث١ىح ا١ٌّٕ٤َٛ -2 ( 3)ٚ (2)ٚاٌّٛضؽح فٟ اٌعذ١ٌٚٓ (o-5052)ِغ١ٕغ١َٛ . [9]ػٍٝ اٌرؼالة -3)ٌٕظف اٌّمطغ فٟ ؼاٌح (ػًّ اٌشثىح )سعُ شثىح اٌؼمذ -3 d) ٠ٚرُ رٌه ؼغة ٔٛع اٌؼٕظش (element) ُاٌزٞ ذ ػٕذ ِٕطمح اٌٍؽاَ ٌٍؼٕاطشذُ ذؽذ٠ذ ؼعُ طغ١ش . أخر١اسٖ ٔظشا ١ّ٘٤ح ٘زٖ إٌّطمح ِماسٔح تّا ٠عاٚس٘ا ػٕذ دساعح اٌرٛص٠غ اٌؽشاسٞ ٚا٤ظٙاداخ ػٕذ ٔمطح اٌٍؽاَ ٌٍٚؽظٛي اْ . (a )5ػٍٝ دلح ػا١ٌح ٌٍٕرائط وّا ِٛضػ فٟ اٌشىً اٌؼٕظش اٌزٞ ذُ ذطث١مٗ فٟ اٌرؽ١ًٍ اٌصالشٟ االتؼاد ٘ٛ (solid 98) ُؼ١س ٠ّرٍه اٌؼذ٠ذ ِٓ دسظاخ اٌؽش٠ح ٚذ ( temp,ux,uy,uz)ذؽذ٠ذ استغ دسظاخ اٌؽش٠ح ٟ٘ ػٍّا اْ . اٌشىً إٌٙذعٟ ٌٍؼٕظش (b5 ) غــٚاٌشىً ٠ٛع دسظاخ اٌؽش٠ح اٌى١ٍح ٌؼ١ٍّح اٌٍؽاَ إٌمطٟ ؼغة ا٤ّٔٛرض دسظاخ فٟ 4× ػمذج 7772اٌزٞ ذُ ذؽ١ٍٍٗ فٟ ٘زا اٌثؽس اٌؽش٠ح فٕؽظً ػٍٝ دسظاخ اٌؽش٠ح اٌى١ٍح ٥ٌّٔٛرض 7772 ×4 = 30088 دسظاخ اٌؽش٠ح اٌى١ٍح ٥ٌّٔٛرض إدخاي اٌّرغ١شاخ اٌشئ١غ١ح ٌؼ١ٍّح اٌٍؽاَ ٚاٌرٟ ذُ دساعرٙا فٟ -4 ( ٚطٛي اٌمٛطذ١اس اٌٍؽاَ, صِٓ اٌٍؽاَ )٘زا اٌثؽس ٚ٘ـــٟ :ٚضّٓ اٌؽذٚد اٌرا١ٌح welding time = (4, 5, 6, 7, 8.) sec welding current = (50, 60,70, 80, 90, 100, 110, 120, 130, 140) amp. arc length = (1.6, 3.2, 4.8) mm ٚٔظشاً ٌظؼٛتح ل١اط دسظاخ اٌؽشاسج ِخرثش٠ا ٌٕمطح اٌٍؽاَ طش٠مح اٌرؽ١ًٍ تطش٠مح اٌؼٕاطش ذُ أػرّادأشٕاء ػ١ٍّح اٌٍؽاَ فمذ ٌٍؽظٛي ػٍٝ اٌرٛص٠غ (ansys)اٌّؽذدج ٚذٛظ١ف تشٔاِط . ٌذسظاخ اٌؽشاسج فٟ ٔمطح اٌٍؽاَ ٚت١اْ إٌّطمح اٌّرأششج تاٌؽشاسج ضّٓ آِش (convergence test)ذُ أخرثاس ذماسب إٌرائط -5 (cnvtpl) ؼ١س ذُ اخز اٌؽشاسج وّشظغ ٌٍّماسٔح ِٓ إٌرائط .اٌّؽغٛتح ػٓ وً ذىشاس boundary conditionsانششوط انحذٌت ٌغشع ذؽ١ًٍ لطؼرٟ اٌٍؽاَ ؼشاس٠ا فال تذ ِٓ ٚضغ اٌظشٚف اٌّؽ١طح ٚاٌرٟ ذعؼً أّٔٛرض اٌؼٕاطش اٌّؽذدج اٌصالشٟ ٚ٘زٖ ,ا٤تؼاد ٌمطؼرٟ اٌٍؽاَ ٚوأٔٙا أشٕاء ػ١ٍّح اٌٍؽاَ فؼال ٕٚ٘ان ٔٛػاْ ِٓ اٌششٚط ,اٌظشٚف ذغّٝ اٌششٚط اٌؽذ٠ح ا٤ٌٚٝ اٌخاطح ترصث١د لطؼرٟ اٌٍؽاَ ٌىٟ ال ذىٛٔاْ ؼشذاْ ,اٌؽذ٠ح ذؽد ذأش١ش اٌمٜٛ اٌّغٍطح ٟٚ٘ ذغاُ٘ فٟ ؼغاب االظٙاداخ ٚاٌصا١ٔح ٟ٘ اٌخاطح تاٌّؽ١ظ اٌؽشاسٞ تؽ١س ذىْٛ ,ٚاٌرشٛ٘اخ ِشاتٙح تمذس اٌّىاْ ٌٍظشٚف اٌؽم١م١ح اٌرٟ ذىْٛ تٙا اٌمطؼر١ٓ .أشٕاء ػ١ٍّح اٌٍؽاَ انششوط انحذٌت انخاطت بانخثبٍج ٌىٟ ٔرّىٓ ِٓ أ٠عاد اٌؽً ٌّؼادالخ طش٠مح اٌؼٕاطش اٌّؽذدج التذ ِٓ ٚضغ ششٚط ؼذ٠ح خاطح ترصث١د اٌمطؼر١ٓ ٚذىْٛ ٘زٖ اٌششٚط ِّٙح ظذا ٤ٔٙا ذّصً ؼاٌح اٌمطؼر١ٓ أشٕاء ػ١ٍّح اٌٍؽاَ ِٚٓ ٘زٖ اٌششٚط ِا ٠ىْٛ ِغؤٚال ػٓ ذصث١د ا٤ّٔٛرض ٠ٚرُ ٘زا ترم١ذ اٌؽشوح ٚذّد إظشاءاخ اٌرصث١د تٛاعطح اعرخذاَ آِش ػٕذ (node)ٌىً ػمذج ((dofؼ١س ذُ اػرثاس ل١ّح (d)اٌرصث١د . ِٕطمح اٌرصث١د ٠غاٚٞ طفش انششوط انحذٌت انخاطت بانخحًٍم انحشاسي ٚذّصً ٘زٖ اٌششٚط وً ِا ٠ؽ١ظ تاٌمطؼر١ٓ ِٓ ظشٚف ؼشاس٠ح تؽ١س ذىْٛ ِشاتٙٗ لذس االِىاْ ٌٍظشٚف اٌؽم١م١ح اٌرٟ ٠ؼًّ ف١ٙا ّٔٛرض ٌٚغشع ذؽ١ٍٍٙا ؼشاس٠ا فاْ اٌششٚط اٌؽذ٠ح ٟ٘ ػثاسج ٤ا ػٓ ِؼاِالخ أرماي ؼشاسج ٚلذ ٚظذخ ل١ّٙا فىأد اػرثاس ٟٚ٘ اٌذسظح اٌرٟ c◦(50)اٌمطؼر١ٓ ذؽد دسظح ؼشاسج ِمذاس٘ا ٚدسظح ؼشاسج ٔمطح اٌٍؽاَ اٌرٟ ذؼرّذ ل١ّرٙا .ذؽ١ظ تٕمطح اٌٍؽاَ )ٚاٌشىً ػٍٝ ِرغ١شاخ اٌٍؽاَ ِٓ صِٓ ٚذ١اس اٌٍؽاَ ٚطٛي لٛط . اٌّرشاوثر١ٓ ٠ث١ٓ اٌششٚط اٌؽذ٠ح اٌخاطح تاٌمطؼر١ٓ( 3 حطبٍك االحًال واسخخالص انُخائح ِغرمش , أٔرماٌٟ(فٟ ٘زٖ اٌّشؼٍح ٠رـُ ذؼش٠ف شىً اٌرؽ١ًٍ . ) transient ( ٚفٟ ِغاٌح اٌٍؽاَ ٠ىْٛ اٌرؽ١ًٍ أٔرماٌٟ )اٌخ ...., ٚلذ ذُ ذطث١ك اٌؽًّ اٌؽشاسٞ إٌاذط ػٓ اٌر١اس ٚاٌثذء تؽً ٠ٚخرٍف اٌرؽ١ًٍ اٌغ١ش اٌخطٟ ػٓ اٌرؽ١ًٍ . اٌؼٕاطش اٌّؽذدج ار إٔا . اٌخطٟ ؼ١س أٗ ػادج ِا٠ؽراض اٌٝ ص٠ادج اوثش فٟ اٌٛلد . ٔؽراض اٌٝ ذىشاس اٌرٛاصْ ػشع انُخائح فٟ ٘زٖ اٌخطٛج ٠رُ ػشع ٔرائط اٌرؽ١ًٍ أٞ ػشع ذٛص٠غ . دسظاخ اٌؽشاسج ػثشِٕطمح اٌٍؽاَ experimental work اندضء انؼًهً messer griesheim multi) ذُ اعرؼّاي ِاوٕح ٌؽاَ ٔٛع wig>g3500-1< )ٟالظشاء ػ١ٍّح ٌؽاَ اٌمٛط اٌىٙشتائ tig spot) )إٌمطٟ تمطة اٌرٕىغرٓ اٌّؽّٟ تاٌغاص اٌخاًِ 98-84، الصفحة 2، العدد 4 مجلة الخوارزمي الهندسية، المجلد منى خضير عباس . د (2008) 86 (1mm ) ٚتغّه al-mg ) )ٌظف١ؽر١ٓ ِرشاوثر١ٓ ِٓ عث١ىح ٚٔٛع (15liter/min)ٚواْ ِؼذي ظش٠اْ اٌغاص . ٌىً ِّٕٙا ٚاعرؼًّ لطة (%99.999)اٌغاص اٌّغرخذَ ٘ٛ االسوْٛ تٕماٚج ٚٔٛع (ewth2)ِٚٓ ٔٛع (3.2mm)اٌرٕىغرٓ تمطش ٚاؼذ . تمطث١ح ِثاششج (dcsp)اٌر١اس اٌّغرخذَ ٘ٛ ذ١اس ِثاشش ٚأظش٠د ػ١ٍّح اٌٍؽاَ إٌمطٟ االٔظٙاسٞ ػٕذ أصِاْ ٌؽاَ mm (1.6, 3.4ٚذ١اساخ ٌؽاَ ِخرٍفح ٚالطٛاي الٛاط ٘ـٟ ٚذُ ل١اط لطشٔفطح . ٚوّا ِٛضؽح فٟ اٌفمشج اٌغاتمح ( 4.8, ٚػّمٙا ػثش اٌّمطغ اٌؼشضٟ ٌٙا تاعرخذاَ (ٚطٍح اٌٍؽاَ )اٌٍؽاَ ِعٙش ضٛئٟ ٠ؽرٛٞ ػٍٝ ػذعح ِذسظح ٚػٕذ ظشٚف اٌٍؽاَ ٚلذ ذُ . اٌّخرٍفح ٚذُ ذؽذ٠ذ اٌظشٚف اٌّصٍٝ ٌّرغ١شاخ اٌٍؽاَ ]14[ِماسٔح ٘زٖ إٌرائط ِغ إٌرائط اٌؼ١ٍّح ٌٍثاؼص١ٓ فٟ اٌّظذس . ٚوزٌه إٌرائط إٌظش٠ح اٌّغرؽظٍح ِٓ اٌثشٔاِط اٌؽاعٛتٟ يُالشت انُخائح . 4 حأثٍش حٍاس انهحاو ٞ اٌرؽىُ فٟ خٛاص ِٕطمح اٌٍؽاَ ف ٠ؼذ اٌر١اس ػاِال ِّٙا اٌّطٍٛتحٔر١عح اٌؽشاسج اٌّرٌٛذج ِٓ ِشٚس اٌر١اس اٌىٙشتائٟ ٚ ٌظٙش اٌّؼذْ ٚذى٠ٛٓ ٚطٍح اٌٍؽاَ ٚذؽغة و١ّح اٌؽشاسج ٟ٘ vٚ ( a )٘ٛ اٌر١اس اٌىٙشتائٟ i ؼ١س أْ q=ivt :واٌراٌٟ ٠ٛضػ ( 4)ٚاٌعذٚي (. sec) ٘ٛ صِٓ اٌٍؽاَ tٚ ( v )اٌفٌٛر١ح أػٍٝ دسظح ؼشاسج ٌّٕطمح اٌٍؽاَ ػٕذ ذ١اسخ ِخرٍفح ٠ٚالؼع ل١ّح -110)ػٕذ ذ١اساخ ِخرٍفح ذرشاٚغ ِٓ ( 3, 1,2 )فٟ ا٤شىاي 140)amp ِٓ5 ٚػٕذ صsec 1.6 ٚطٛي لٛطmm ٓذث١ اٌرٛص٠غ اٌؽشاسٞ خالي لطش ٚػّك ٔمطح اٌٍؽاَ ٚلذ تٍغد دسظح ( amp 110ػٕذ ذ١اس)اٌؽشاسج ػٕذ إٌّطمح اٌّراششج تاٌؽشاسج ( amp 140)اِا ػٕذ ذ١اس c(119.756538.209)°ِات١ٓ ٠الؼع ػٕذ اٌر١اساخ . c(121.208 -619.662)°ذشاٚؼد ت١ٓ اٌؼا١ٌح ظذا أْ ػّك اٌّؼذْ إٌّظٙش ٠خرشق عّه اٌمطؼر١ٓ إٌٝ ٔٙا٠ح اٌظف١ؽح اٌغف١ٍح ِٚٓ شُ ذٛلغ فشً اٌٍؽاَ تغثة خشٚض اٌّؼذْ إٌّظٙش خاسض ٔمطح اٌٍؽاَ ػٕذ ( splashing )ٚذٕاشش ٚػّك ِٕطمح اٌٍؽاَ ااٌغطػ اٌفاطً ِّا ٠ؤدٞ إٌٝ ٔمظاْ عّه (weld depth) ٟٚاوذخ ٔرائط اٌثؽس اٌؽاٌٟ ِطاتمرٙا ٌٍٕرائط اٌر أِا ذٛص٠غ . 1]102, 11 , ]ذٛطً ا١ٌٙا اٌثاؼص١ٓ فٟ اٌّظادس دسظاخ اٌؽشاسج خالي لطش ٔمطح اٌٍؽاَ فأٗ ٠ضداد ِغ ص٠ادج ذ١اس اٌٍؽاَ ِٚٓ ِالؼظح ا٤شىاي أػالٖ ٠الؼع أْ ص٠ادج اٌر١اس إٌٝ ذؤدٞ إٌٝ ػذَ أرظاَ اٌرٛص٠غ اٌؽشاسٞ 140amp) (ِمذاس ٠ؤدٞ ٌٕمطح اٌٍؽاَ ٚ٘زا ٠ؼٕٟ ذى٠ٛٓ ٚطٍح ٌؽاَ غ١شِٕرظّح ِّا ذٛضػ ذٛص٠غ دسظاخ ( 8, 7, 6) ٚا٤شىاي .اٌٝ فشً اٌٍؽاَ 1.6mm ٚطٛي اٌمٛط 5secاٌؽشاسج ٌٕمطح اٌٍؽاَ ػٕذ صِٓ . ٚػٕذ ذ١اساخ ِخرٍفح آخ اٌث١ا١ٔح ٌٍرٛص٠غ اٌؽشاسٞ ق اٌؼال(10 ,9) ٠ٛضػ اٌشىالْ ٠ٛضؽاْ خالي لطش ٔمطح اٌٍؽاَ ٚػّك اٌٍؽاَ ػٍٝ اٌرٛاٌٟ ؼ١س اْ ٕ٘اٌه ػاللح طشد٠ح ت١ٓ لطش إٌمطح ٚاٌر١اس ٚوزٌه ت١ٓ عّه ٠ّىٓ أْ ٔؽذد ِٕطمح اٌٍؽاَ ٚإٌّطمح اٌّرأششج اٌٍؽاَ ٚاٌر١اس تاٌؽشاسج خالي لطش ٚػّك اٌٍؽاَ ٚاْ ص٠ادج اٌر١اس ذؤشش فٟ ص٠ادج إْ اٌّؼذْ إٌّظٙش 140amp) (عّه اٌٍؽاَ ؼ١س أٗ ػٕذ ذ١اس إٌٝ (ا٤ٌٚٝ )٠خرشق عّه اٌظف١ؽر١ٓ أٞ ِٓ اٌظف١ؽح اٌؼ٠ٍٛح ٚ٘زا ٠ؼٕٟ أْ ػّك اٌّؼذْ . (اٌصا١ٔح)أعفً اٌظف١ؽح اٌغف١ٍح ِٓ عّه اٌمطؼح اٌصا١ٔح ٚ٘زا % 100 ٠ظً اٌٝ ٔغثح إٌّظٙش ٠ؼطٟ ٔمطح ٌؽاَ فاشٍح الٔٙا ١ٌغد ضّٓ اٌغّه اٌّغّٛغ تٗ اٌزٞ اٌرٟ ذؼطٟ ٔمطح ج اٌغف١ٍح ِٓ عّه اٌمطغ%(80-20 )٘ٛإٌغثح ٚظاءخ ٘زٖ ]3,2,1[ ٌؽاَ ظ١ذج ضّٓ اٌغّه اٌّغّٛغ تٗ .ٌٕرائط اٌرعاسب اٌؼ١ٍّح اٌرٟ أظش٠د فٟ ٘زا اٌثؽسِطاتمح إٌرائط حأثٍش صيٍ انهحاو إْ صِٓ ٚذ١اس اٌٍؽاَ ٌّٙا ٔفظ اٌرأش١ش فٟ و١ّح اٌؽشاسج اٌّرٌٛذج ٚاٌّطٍٛتح ٌرى٠ٛٓ ٚطٍح اٌٍؽاَ ٌٚىٓ صِٓ اٌٍؽاَ الً ذأششاً ِٓ اٌر١اس ٚتاٌراٌٟ ص٠ادج فٟ ِغاؼح إٌّطمح اٌّرؼشضح فٟ ٌؽاَ . [13]ٌٍؽشاسج ِّا ٠ؤشش فٟ ص٠ادج ل١ُ لطش ِٕطمح اٌٍؽاَ ا١ٌّٕ٤َٛ ٠فضً اعرخذاَ ا٤صِاْ اٌمظ١شج ٌغشع ذم١ًٍ فمذاْ اٌؽشاسج إٌٝ اٌّؽ١ظ اٌخاسظٟ ٚ٘زا ٠ؼضٜ إٌٝ اٌرٛط١ٍ١ح اٌؼا١ٌح ٠ٛضػ ل١ّح (5)ٚاٌعذٚي .ٚ٘زا ِا ٠ؤوذٖ اٌثؽس اٌؽاٌٟ. ١ٌّٕ٥ٌَٛ ٚاصِٕح (70amp)دسظاخ ؼشاسج ِٕطمح اٌٍؽاَ ػٕذ شثٛخ ذ١اس ِٓ (4.8mm) ٚػٕذ طٛي لٛط(4-7)ِخرٍفح ذرشاٚغ ت١ٓ اٌّالؼع اْ ص٠ادج صِٓ اٌٍؽاَ ٠ؤدٞ اٌٝ ص٠ادج ذؼشع ِٕطمح . اٌٍؽاَ ٌٍر١اس اٌرٟ (16 ,15 ,14 , ,1213 ,11) ِٚٓ ِالؼظح ا٤شىاي ٌؽشاسج ٌمطش ٚػّك اٌٍؽاَ خالي اٌظف١ؽر١ٓ ذٛص٠غ دسظاخ اذث١ٓ ٠ٚالؼع اْ ٕ٘اٌه ذثا٠ٓ وث١ش فٟ ذٛص٠غ دسظاخ ِٕاطك اٌٍؽاَ اْ ص٠ادج صِٓ اٌٍؽاَ ٠ؤدٞ اٌٝ ص٠ادج ِغاؼح ِٕطمح اٌٍؽاَ فضال ػٓ ص٠ادج ػّك اٌّؼذْ إٌّظٙش ٌٕمطح اٌٍؽاَ ٚطٛال اٌٝ ٔٙا٠ح اِا ػٕذ االصِاْ اٌم١ٍٍح فاْ اٌؽشاسج اٌّرٌٛذج . اٌظف١ؽح اٌصا١ٔح ذىْٛ غ١ش واف١ح ٌظٙشاٌّؼذْ ٌٍعضء٠ٓ اٌّرشاوث١ٓ ِٚٓ شُ ذؼطٟ ذغٍغال ل١ًٍ فرىْٛ خٛاص اٌٛطٍح ِٕخفضح ف١ٕرط ػٓ رٌه ٚطٍح (81)ٚ (17)اِا اٌشىالْ . فاشٍح ٚغ١ش ِطاتمح ٌٍّٛاطفاخ ف١ٛضؽاْ اٌؼاللح ت١ٓ صِٓ اٌٍؽاَ ٚلطش ٔمطح اٌٍؽاَ ٚػّك اٌٍؽاَ ؼ١س ٠ضداد لطش (70amp (ػٍٝ اٌرٛاٌٟ ػٕذ ذ١اسشاتد ِمذاسٖ ٔمطح اٌٍؽاَ ٚػّك اٌٍؽاَ ِغ ص٠ادج صِٓ اٌٍؽاَ ِّا ٠ٛدٞ اٌٝ . ص٠ادج إٌّطمح اٌّراششج تاٌؽشاسج إْ ص٠ادج ذ١اس ٚصِٓ اٌٍؽاَ ذؤششاْ تشىً وث١ش فٟ ص٠ادج دسظح ؼشاسج ٔمطح اٌٍؽاَ ٚاْ أػٍٝ دسظح ؼشاسج فٟ ِؼذْ اٌٍؽاَ ٟ٘(698) o c َػٕذ ذ١اس ٌؽا (130amp)َٚصِٓ ٌؽا (6sec) ْ ِشٚس اٌر١اس ٌفرشج ص١ِٕح ط٠ٍٛح mm 6. . 1٤ٚطٛي لٛط ٠ؤدٞ إٌٝ ص٠ادج و١ّح اٌؽشاسج اٌّرٌٛذج اٌٝ ل١ُ وث١شج ِّا لذ ذؤدٞ إٌٝ فشً ٚطٍح اٌٍؽاَ, ٚ٘زٖ إٌرائط ذرٛافك ِغ ِا ذٛطً إ١ٌٙا ذماسب إٌرائط اٌؼ١ٍّح (19) ٠ٚٛضػ اٌشىً .[15,14]اٌثاؼص١ٓ ِغ إٌرائط إٌظش٠ح ؼ١س ٠ضداد لطش ٔمطح اٌٍؽاَ ِغ ص٠ادج ذ١اس ٌٚٛؼع ِٓ mm 1.6.ٚطٛي لٛط sec 6 اٌٍؽاَ ػٕذ صِٓ خالي اٌفؽض اٌؼ١أٟ ٚاٌفؽض اٌّا٠ىشٚعٛتٟ ٌٍّمطغ اٌؼشضٟ ٌٛطٍح اٌٍؽاَ ٌٍٍّؽِٛح ػٕذ اٌظشٚف اٌّصٍٝ ٌّرغ١شاخ اٌٍؽاَ أٔرظاَ ٚطٍح اٌٍؽاَ ٚاٌرغٍغً اٌع١ذ ٌّٕطمح اٌٍؽاَ ػثش اٌغطػ اٌفاطً ِات١ٓ اٌظف١ؽر١ٓ ٚوزٌه خٍٛ ِٕطمح اٌٍؽاَ ِٓ اٌؼ١ٛب اٌزٞ ٠ّصً طٛسج فٛذٛغشاف١ح ٌٛطٍح (20)وّا ِٛضػ فٟ اٌشىً ذماسب إٌرائط إٌظش٠ح (a,b 20)٠ٚالؼع ِٓ اٌشىً .اٌٍؽاَ ِٓ ) ِغ إٌرائط اٌؼ١ٍّح ( ansys 5.4 )اٌّغرؽظٍح ِٓ تشٔاِط ِٓ ؼ١س شىً ٚلطشٔمطح اٌٍؽاَ (ذعاسب اٌفؽض اٌّعٙشٞ . ٚػّك اٌرغٍغً ٌّٕطمح اٌٍؽاَ إٌّطمح اٌّراششج ٟ٘ ف١ٛضػ ِٕاطك اٌٍؽاَ (20c) أِا اٌشىً ذىْٛ راخ ؼث١ثاخ ط١ٌٛح ِٕٚطمح اٌٍؽاَ ٚاٌرٟ ( haz)تاٌؽشاسج اٌشىً ِٚرعٙح ٔؽٛ ِشوض ٔمطح اٌٍؽاَ ت١ّٕا ذىْٛ اٌؽث١ثاخ ٔاػّح ِٚرغا٠ٚح اٌّؽاٚسفٟ ٚعظ ِٕطمح اٌٍؽاَ ٚعطػ اٌٍؽاَ ؼ١س ٠ىْٛ ػٕذ٘ا ِؼذي اٌرثش٠ذ ػا١ٌا أٞ اْ ِؼذي ّٔٛ اٌؽث١ثاخ ٠ىْٛ ل٣١ٍ ٠ٚؼضٜ ٘زا اٌٝ اٌّٛطٍثح اٌؽشاس٠ح اٌؼا١ٌح ٌغث١ىح ا١ٌّٕ٤َٛ . ٚفمذاْ اٌؽشاسج تغشػح اٌٝ اٌٙٛاء 98-84، الصفحة 2، العدد 4 مجلة الخوارزمي الهندسية، المجلد منى خضير عباس . د (2008) 87 conclusions االسخُخاخاث ٞاْ اعرخذاَ اٌؽاعثح فٟ ذؽ١ًٍ ِٚؽاواج اذٛص٠غ اٌؽشاس .1 االتؼاد تطش٠مح اٌؼٕاطش اٌّؽذدج ٚرٌه تثٕاء أّٔٛرض شالشٟ خالي عاػذ وص١شا تاٌٛطٛي اٌٝ ذٛص٠غ دسظاخ اٌؽشاسج ٔمطح اٌٍؽاَ ٚاٌرٟ ٠ظؼة ل١اعٙا ػ١ٍّا ٚلذ ٚفشخ وص١شا فٟ .ٚاٌىٍفح اٌٛلد ٚاٌعٙذ اٌرٛص٠غ اٌؽشاسٞ ٌمطش ٔمطح اٌٍؽاَ ٚوزٌه ػّك اٌٍؽاَ .2 ٠ضداد ِغ ص٠ادج ذ١اس ٚصِٓ اٌٍؽاَ ٚػٕذ طٛي لٛط شاتد . خالي اٌغطػ اٌفاطً ت١ٓ اٌمطؼر١ٓ اٌّرشاوثر١ٓ ٠ضداد ِغ ص٠ادج طٛي (d-3)إْ اٌرٛص٠غ اٌؽشاسٞ ٥ٌّٔٛرض .3 اٌمٛط ػٕذ شثاخ ِرغ١شاخ اٌٍؽاَ ا٤خشٜ ٚتاٌراٌٟ ٠ؤشش فٟ ذشرد اٌؽشاسج ػٍٝ ِغاؼاخ ٚاعؼح ِّا ٠مًٍ ِٓ وفاءج ٚػذَ أرظاَ ٔمطح اٌٍؽاَ ِٚٓ شُ ٠ؼطٟ ذغٍغً ل١ًٍ ٌٍّؼذْ . إٌّظٙشٌٛطٍح اٌٍؽاَ اٌرشاوث١ح ِٕطمح اٌٍؽاَ ٚإٌّطمح اٌّرأششج تاٌؽشاسج ذرؼشع إٌٝ أؽذاس .4 فٟ دسظاخ اٌؽشاسج تغثة اٌذٚسج اٌؽشاس٠ح وث١ش٠ٓٚذثا٠ٓ اٌشذ٠ذج ٔر١عح ٌؼ١ٍّرٟ اٌرغخ١ٓ ٚاٌرثش٠ذ, ٚوزٌه تغثة اٌّٛط١ٍح اٌؽشاس٠ح اٌؼا١ٌح ١ٌّٕ٥ٌَٛ ٚعثائىٗ ؼ١س ٚطٍد أػٍٝ ل١ّح ٌذسظح اٌؽشاسج ٌٍّؼذْ إٌّظٙش فٟ ٔمطح اٌٍؽاَ ٌؽاَ ٚذ١اس 6secذمش٠ثاً ػٕذ صِٓ c(698)°إٌٝ 130amp 1.6 ٚطٛي لٛطmm ٖشُ أخفضد تاذعا .اٌّؼذْ ا٤عاط اٌثؼ١ذ ػٓ ِٕطمح اٌٍؽاَ tig ٌؼ١ٍّح اٌٍؽاَ إٌمطٟ تطش٠مح ذٛص٠غ ؼشاسٞإْ أفضً .5 ؼ١س أػطٝ (7sec)ٚصِٓ ٌؽاَ (90amp)واْ ػٕذ ذ١اس ذٛص٠ؼاً ؼشاس٠اً ِرعأغاً ٚأرظاِا ٌٕمطح اٌٍؽاَ ٚذغٍغالً ظ١ذاً . ِٕاعثاً فٟ اٌظف١ؽح اٌغف١ٍح ٚتاٌراٌٟ ٌؽاَ ِٕاعة ذماسب إٌرائط إٌظش٠ح ِغ إٌرائط اٌؼ١ٍّح فٟ ل١اط ٚذؽذ٠ذ .6 ذغ١شاخ َلطشٚػّك ٔمطح اٌٍؽاَ ٚػٕذ اٌظشٚف اٌّصٍٝ ي .ػ١ٍّح ِٓ ذ١اس ٚصِٓ اٌٍؽاَ ٚوزٌه طٛي اٌمٛط . al-mg o)-(5052[9] نسبٍكت (%wt) انخشكٍب انكًٍٍاوي (1)خذول element si mg fe mn cu cr zn al wt% 0.215 2.26 0.21 5 0.0042 0.04 0.3025 0.00250 96.9 [ al-mg(o-5052 [)9 انخىاص انًٍكاٍَكٍت نسبٍكت (2)خذول طالدة hvفٍكشص طالدة بشٌُم hb يطٍهٍهال δ% إخهاد خضىعال σy, mpa انمضإخهاد τ, mpa إخهاد انشذ σt, mpa اندساءةيؼايم g, gpa انًشوَت يؼايم e, gpa 50 50 25 90 125 195 26.3 70 [9(]o-5052)يغٍُسٍىو -انخىاص انحشاسٌت نسبٍكت أنًٍُىو (3)خذول َسبت بىٌسٍ  انكثافت  kg/m 3 دسخت انسٍىنت tliq, o c دسخت انخدًذ tsol, o c انسؼت انحشاسٌت cp, j/kg.k يؼايم انخًذد انحشاسي  , µm/m-cº معامل التوصيل الحراري  , w/m.k 0.33 2860 650 605 901 23.7 138 حىصٌغ دسخاث انحشاسة فً َمطت انهحاو ػُذ حٍاساث يخخهفت وطىل انمىط (4)خذول 1.6mm ٍوصي sec5 (amp) حٍاس انهحاو 140 130 120 110 c°) )دسخت انحشاسة 690.87 686.522 682.174 577.826 حىصٌغ دسخاث انحشاسة فً َمطت انهحاو ػُذ أصياٌ يخخهفت وطىل انمىط (5)خذول mm 4.8وحٍاس amp 70. 98-84، الصفحة 2، العدد 4 مجلة الخوارزمي الهندسية، المجلد منى خضير عباس . د (2008) 88 . tig spot)) يبذا ػًهٍت انهحاو انُمطً(1)شكم .انؼاللت يابٍٍ ابؼاد انمطؼخٍٍ انًشاد نحايهًا (2)شكم (sec)صيٍ انهحاو 7 6 5 4 (c°)دسخت انحشاسة 672.609 666.522 660.435 654.348 98-84، الصفحة 2، العدد 4 مجلة الخوارزمي الهندسية، المجلد منى خضير عباس . د (2008) 89 .ٌىضح انششوط انحذٌت نخثبٍج انمطؼخٍٍ (3)شكم .ٌبٍٍ ابؼاد انمطؼخٍٍ انًشاد نحايهًا (4)شكم .(d-2)وحانت (d-3)ٌىضح انشبكت فً حانت (a5 )شكم 98-84، الصفحة 2، العدد 4 مجلة الخوارزمي الهندسية، المجلد منى خضير عباس . د (2008) 90 .شكم انؼُظش انزي أسخخذو فً انخحهٍم (b5 )شكم .1.6mmانمىط وطىلamp 110 وحٍاس5secٌىضح حىصٌغ دسخاث انحشاسة نُمطت انهحاو ػُذ صيٍ (6)شكم .1.6mmانمىط وطىلamp 120ِ وحٍاس5secٌىضح حىصٌغ دسخاث انحشاسة نُمطت انهحاو ػُذ صيٍ (7)شكم 98-84، الصفحة 2، العدد 4 مجلة الخوارزمي الهندسية، المجلد منى خضير عباس . د (2008) 91 1.6mm وطىل انمىط amp 140 وحٍاس 5secٌىضح حىصٌغ دسخاث انحشاسة نُمطت انهحاو ػُذ صيٍ ( 8 )شكم .1.6mm وطىل انمىط 5secدسخاث انحشاسة يغ لطش َمطت انهحاو ػُذ صيٍ ٌىضح حىصٌغ ( 9 )شكم 0 100 200 300 400 500 600 700 800 0 0.5 1 1.5 2 2.5 weld depth (mm) te m p e ra tu re (c ) 110 ñçíê 120 ñçíê 140 ñçíê .1.6mmوطىل انمىط 5secٌىضح حىصٌغ دسخاث انحشاسة يغ ػًك انهحاو ػُذ صيٍ ( 10 )شكم 0 100 200 300 400 500 600 700 800 78 80 82 84 86 88 90 92 94 96 weld spot diameter(mm) te m p e ra tu re (c ) 110 ñçíê 120 ñçíê 140 ñçíê 98-84، الصفحة 2، العدد 4 مجلة الخوارزمي الهندسية، المجلد منى خضير عباس . د (2008) 92 .4.8mm وطىل انمىط amp 70 وحٍاس 4secٌىضح حىصٌغ دسخاث انحشاسة فً َمطت انهحاو ػُذ صيٍ (11 )شكم .4.8mmانمىط وطىل 70amp و sec 5ٌىضح حىصٌغ دسخاث انحشاسة فً َمطت انهحاو ػُذ صيٍ (12 )شكم 4.8mmنمىطاوطىل 70a وحٍاس 6secٌىضح حىصٌغ دسخاث انحشاسة فً َمطت انهحاو ػُذ صيٍ ( 13 )كم ش .4.8mmوطىل انمىط 70amp وحٍاس 7secٌىضح حىصٌغ دسخاث انحشاسة نُمطت انهحاو ػُذ صيٍ ( 14 )شكم 98-84، الصفحة 2، العدد 4 مجلة الخوارزمي الهندسية، المجلد منى خضير عباس . د (2008) 93 0 100 200 300 400 500 600 700 800 78 83 88 93 98 weld spot diametre(mm) t e m p e r a tu e r ( c ) 4 sec 5 sec 6 sec 7 sec 70ampحٍاسٌىضح حىصٌغ دسخاث انحشاسة يغ لطش َمطت انهحاو ػُذ ( 15 )شكم .الصيُت يخخهفتmm 4.8 وطىل انمىط 0 100 200 300 400 500 600 700 800 0 0.5 1 1.5 2 2.5 weld depth (mm) t e m p e rt u re ( c ) 4 sec 5 sec 6 sec 7 sec .70ampحٍاسانهحاو ػُذ ػًك ٌىضح حىصٌغ دسخاث انحشاسة يغ ( 16 )شكم 98-84، الصفحة 2، العدد 4 مجلة الخوارزمي الهندسية، المجلد منى خضير عباس . د (2008) 94 1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 3 4 5 6 7 8 weld time (sec) w e ld d e p th ( m m ) 70 amp 10 10.5 11 11.5 12 12.5 13 13.5 14 70 90 110 130 150 weld current (amp) w e ld s p o t d im e te r( m m ) theoretcal simulation experimental work ألصيُت يخخهفتmm 4.8 وطىل انمىط 10 10.5 11 11.5 12 12.5 13 13.5 3 4 5 6 7 8 weld time (sec) w e ld d ie m e tr ( m m ) 70 amp 70ampحٍاس انؼاللت انبٍاٍَت بٍٍ صيٍ انهحاو ولطش يُطمت انهحاو ػُذٌىضح (17 )شكم .4.8mm وطىل انمىط sec 6 انؼاللت انبٍاٍَت بٍٍ انخٍاس ولطش َمطت انهحاو ػُذ صيٍ انهحاوٌىضح ( 18 )شكم .1.6mm وطىل انمىط sec 6 انؼاللت انبٍاٍَت بٍٍ انخٍاس ولطش َمطت انهحاو ػُذ صيٍ انهحاوٌىضح ( 19 )شكم .1.6mmوطىل انمىط 98-84، الصفحة 2، العدد 4 مجلة الخوارزمي الهندسية، المجلد منى خضير عباس . د (2008) 95 (( a انُخائح انُظشٌت b) ) انُخائح انؼًهٍت (c ) ٌىضح طىسة فىحىغشافٍت نهًمطغ انؼشضً نىطهت انهحاو انُمطً بمطب انخُكسخٍ (20 )شكم ػُذ انظشوف انًثهى نًخغٍشاث انهحاو ( tig spot )انًحًً بانغاص انخايم . 7xػُذ لىة حكبٍش ( 1.6mm وطىل لىط 130amp نحاو وحٍاس ال6secصيٍ انهحاو ) 98-84، الصفحة 2، العدد 4 مجلة الخوارزمي الهندسية، المجلد منى خضير عباس . د (2008) 96 references [1] stuart w. gibson, "advanced welding", first published by macmillan press ltd, london, 1997. [2] society for american metal, metals handbook, vol.6, 9th edition, copyright, 1983. [3] sindo kou, "welding metallurgy", 2 nd edition, john wiley & sons, inc. publication, 2003. [4] justin d. francis, "welding simulations of aluminum alloy joints by finite element analysis", msc.thesis, virginia polytechnic institute and state university, blacksburg ,virginia, apirl 2002 . [5] daniel berghand, " simulation of welding and stress relief heat treating in the development of aerospace components", licentiate thesis, luleal tekniska university, 2001 . [6] finite element analysis, theory and application with ansys”, second moaveni, prentice hall, 1999. [7] huebner k. h. and thornton e. a., “the finite element method for engineering” , 2 nd edition, wileyintrscience, publication, 1982. [8] hidekazu murakawa and jianxun zhang "fem simulation of spot welding process (report i) – effect of initial gap on nugget formation", trans. jwri, vol.27, no.1, 1998, pp75-88. [9] “aluminum select physical and elastic properties”, matter project, the university of liverpool, http://www.matter.com 2001 [10] 10-n.gomesan,v.p. rayghupathy, “predication of temperature distribution during circumferential welding of thin pipes using finite element method”, welding journal, vol.7(1), february ,1995, pp.34-45. [11] aravintton a, v.balendron, “modeling and simulation of a spot welding process an overview”, department of computing trent university, burton st nottingham http://www dcutn.ntu.com 2001. [12] h.a. nied, “the finite element modeling of the resistance spot welding process”, welding journal, vol. 63, no. 4, 1984, pp. 1235-1325. [13] miller electric mfg. co.,"hand book for resistance spot welding ", usa, july 2005, pp1-12. www.millerwelds.com. [14] 14muna k.a. & haitham y. abudm.,"a study effect of some variables in tig spot welding for (aluminummagensium) alloy".journal of engineering. college of engineering, university of baghdad, no.2,vol.11. 2006, pp.1930. [15] 15abbass f. ," study of tig spot in al-mn alloy, msc.thesis university of technology, 2001. http://www.mater.com2001/ http://www.mater.com2001/ http://www.millerwelds.com/ 98-84، الصفحة 2، العدد 4 مجلة الخوارزمي الهندسية، المجلد منى خضير عباس . د (2008) 9797 simulation of temperature distribution in tig spot welds of (al-mg) alloy using finite element method dr. muna k abbas* dr.abdul hussain g. al-maliky** ahlam abid ameer alkhafajy** * dept. of production and metallurgy engineering ,university of technology, baghdadiraq **dept. of educational technology , university of technology, baghdadiraq * e-mail : mukeab2005@yahoo.com (received 11 julay2006 ; accepted 24 september 2007) abstract this research concern to analyse and simulate the temperature distribution in the spot welding joints using tungsten arc welding shielded with inert gas (tig spot) for the aluminum-magnesium alloy type (5052-o). the effect of and the quantity of the heat input that enter the weld zone has been investigated welding current, welding time and arc length on temperature distribution. the finite element method (by utilizing programme ansys 5.4) is presented the temperature distribution in a circular weld pool and the weld pool penetration (depth of welding) through the top sheet ,across the interface into the lower sheet forming a weld spot. a three dimensional (3-d) model has been constructed to study the temperature distribution and the depth or penetration of the weld spot. the results showed that the weld zone and heat affected zone (haz) suffer from high temperature variation caused by severe thermal cycle. the temperature reaches the highest value of the melt metal at the weld spot 698°c at weld current 130 amp, weld time 6 sec and arc length 1.6 mm, then drops further away from the weld spot in the direction the base metal. figuers were plotted to explain the results and to show the temperature distribution and its value in the weld spot and heat effected zone. mailto:mukeab2005@yahoo.com al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 1324 (2014) using termodeck system for pre-cooling/ heating to control the building inside conditions wahid s. mohammad* talib k. murtadha** karrar a.ahmed*** *,**,***department of machine and equipment engineering / university of technology *emial: wahid1953@yahoo.com **emial: talib_km@yahoo.com ***email: alkarnawi@yahoo.com (received 24 march 2014; accepted 13 july 2014) abstract in this paper, experimental study has been done for temperature distribution in space conditioned with ventilation hollow core slab (termodeck) system. the experiments were carried out on a model room with dimensions of (1m 1.2m 1m) that was built according to a suitable scale factor of (1/4). the temperature distributions was measured by 59 thermocouples fixed in several locations in the test room. two cases were considered in this work, the first one during unoccupied period at night time (without external load) and the other at day period with external load of 800w/m 2 according to solar heat gain calculations during summer season in iraq. all results confirm the use of termodeck system for ventilation and cooling/heating purposes in arid and hot climate for its ease, simple and good comfort performance and to save energy and improve the overall energy performance of the building by reducing the peak load. keywords: termodeck, thermal storage, ventilated hollow core slab (vhcs), night ventilation, pre-cast concrete. 1. introduction during the last few years comfort requirements, indoor air quality and energy efficiency show an increasing trend. in consequence, highest numbers of passive techniques have been reintroduced in order to decrease or eliminate the need for mechanical ventilation, cooling and heating thereby reduce energy consumption. total energy saving potential can be increased by the active utilization of the building mass. one of these active strategies is utilizing ventilated hollow core slab (vhcs) so in many literatures, the active hollow core slab system has different terminologies such as “ termodeck system ”, “advanced fabric thermal storage”, and “ thermally activated building system ” (tabs) [1]. termodeck is a fanassisted, heating, cooling and ventilation system that uses the high thermal mass of structural, hollow core slabs through which warmed or cooled fresh air is distributed as shown in figure (1). the vhcs is a precast slab of pre-stressed concrete that has tubular voids extending the full length of the slab. in this technique, ventilation air is passed through the hollow cores of the ceiling slabs; therefore the airflow will increase the convective heat transfer. energy savings from this system have been reported to be between 13% and 70%, depending on the building type and the prevailing weather conditions [1,2]. by forming perpendicular coupling airways between the hollow cores, it is possible to form a 3 or 5 pass circuit through which supply air may pass. the termodeck system achieves good heat transfer between the incoming air and the concrete wahid s. mohammad al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 13 24 (2014) 14 slab by ensuring turbulent airflow through the hollow cores. this is achieved by using a core air velocity of approximately 1m/s, which enables heat to be stored at a rate of between 10 and 40 w/m² of floor area ceiling , depending on the air temperatures involved [3]. fig.1. the termodeck system. various studies have shown the benefits of using ventilated slab systems. shaw, et al. [4] reported that the active use of the thermal properties of the mass within the ventilated slab not only saved energy through reducing fan and coil power in peak time, but also had a thermal comfort advantage because the increased radiant heat transfer between the occupant and the space allows the occupants to feel cooler at the same air temperature. barnaby, et al [5] simulated the thermal behavior of a hollow core slab system and concluded the system could provide an energy reduction between 13% and 30% for the peak cooling load. other studies have developed numerical models to simulate the thermal properties and estimate the system performance of hollow core slab systems under particular conditions. standeven et al. [6] presented a study on one of the existing buildings using termodeck, elizabeth fry building at the university of east anglia in uk. the monitored data showed that:  heating and cooling energy consumption is half that of a conventional building of the same type.  use of termodeck provides good levels of thermal comfort. occupant satisfaction and productivity is high.  capital and maintenance costs are low. karlström [7], treated the modeling and testing of hollow core concrete elements for heat storage and heat distribution via the building construction thermally activated building system, tabs, using ventilated hollow core concrete element, this system is analyzed as well as optimized for effective use of low valued energy sources. this lead to a renewed environmentally friendly industrial building concept that provides good comfort to a low cost. also confirm the biggest advantage of the system is the capability to store and distribute heat in the hollow core concrete elements which has a positive effect on energy use ren and wright [8] introduced a transient simulation model for a three core ventilated slab using a lumped parameter thermal network model. when the heat transfer coefficient of the corner of the air path was assumed to be 50 times higher than the heat transfer coefficient in the straight sections of the core, the developed model showed acceptable accuracy when compared to measured data for a simple test room located in a large laboratory building. russell and surendran [9] investigated the system performance through a two-dimensional (2d) finite difference model. in this study, when air at 16.9°c was assumed to be continuously circulated through three cores for 14 hours, the cooling potential of the system increased by 335 percent in comparison to a traditional slab configuration with night ventilation. barton, et al. [10] developed a numerical tool using a two-dimensional finite difference model to investigate the thermal performance of a ventilated slab system. the theoretical results for both steady state and transient conditions showed that the corner sections of the cavity loop had little impact on the overall slab performance, while the bending or corner sections are regarded as important factor to the system performance by other studies [8]. they also theoretically evaluated the damping effect between a five core and a three core slab system. corgnati and kindinis [11] proposed a numerical model of the slab system based on a finite difference model. the slab is similar to a heat exchanger in this model. the authors implemented their model within a simulation tool to investigate the performance of the free cooling potential and indoor thermal conditions in an office. comparing a traditional ventilation system with the night ventilation operation, the hollow core ventilation system offered a more acceptable indoor temperature during the cooling period under various internal heat gains for a mediterranean climate. wahid s. mohammad al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 13 24 (2014) 15 recent research on ventilated slab systems using a hollow core slab indicates that energy savings can be achieved when the ventilated slab system is used as a thermal storage element to cool the building, and various numerical models have been developed to characterize the performance of the system. however, most experimental and theoretical model results are based on measured or simulated energy consumption for a particular space, day and climate condition. this does not allow any general conclusions to be made that would extend these results to different buildings, locations, and climate conditions. the most recent study about this system is published by xinhua et al. [12] , where present a comprehensive review of the research and application of active hollow core slabs in building systems for utilizing low energy sources. they point out that the active hollow core slabs are widely used mostly in europe for reducing energy consumption and improving indoor environment, their detailed performance investigations and evaluations are still rough and limited. in addition, it seems that there is no report on the researches and applications of these active slabs in asia. more works on the active slabs are still needed for promoting these slabs to be used in low energy architectures wherever the climate is appropriate, and therefore the present study was carried out to fulfil their requirements. 2. experimental work the termodeck system employed in this experimental equipment consist of a rectangular room with an air conditioner works as a conditioned unit, the schematic diagram for the whole apparatus shown in figure (2). the test rig is used to study the effect of two operating parameters, the first one is "the core air velocity" and the second is "the inlet air temperature to the slab" to determine the possibility of using termodeck system in arid climate especially in iraq. 2.1. design of termodeck system the hollow core concrete slabs can be manufactured in a range of geometries [10,13]. figure (3) shows the geometry used in this study; (1000 mm length, 1200 mm width, 240 mm height of the slab and the core diameter was 160 mm). figure (4) shows the steps of manufacturing of termodeck system the holes are closed at the end by fiber wood material, so the air enter to the test room through elbow apart with the same diameter. five convector heaters are placed in the upper face of the slab inside a grove with approximately 1000 mm length to emulate the solar heat gains during normal daily operation of the ventilated slab system. during these tests, the room heat gains were imitated by the convector heaters of approximately 800 w/m² output as the maximum solar heat gains during summer season at 21th july. all of the heaters are connected to current controller to provide the system with the required energy. the whole system are covered with two layers of glass wool insulation 20 mm thickness for each layer and (0.04 w/m.°c) thermal conductivity to prevent heat gain losses. wahid s. mohammad al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 13 24 (2014) 16 fig. 2. schematic diagram of the test rig. fig. 3. termodeck cross-section core geometry. 1 termodeck system 4 supply duct 7 air damper 10 stand 2 test room 5 duct heaters 8 hotwire position 11 current control 3 air conditioner 6 termodeck heaters 9 control board 12 room wall (polystyrene) wahid s. mohammad al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 13 24 (2014) 17 fig. 4. steps of manufacturing the termodeck system 2.2. experimental apparatus parts the experimental room can be described as an isolated space with well insulated walls and floor by polystyrene with (100 mm) thickness in order to study the performance of the termodeck system. it represent an office test room with dimensions (l=4 m, w=4.8 m and h=3.75 m). a suitable scale factor was assumed to find the model dimensions: (lm / lp = 1/4). the model room dimensions accordingly are (lm = 1200 mm, wm = 1000 mm and hm = 1000 mm) where the subscripts m and p refer to model and prototype, respectively. in this study the velocities are 1m/sec and 1.6m/sec for all test cases. fifty nine thermocouples type k were used for the temperature measurements. these sensors are fixed as follows: 1. fifteen thermocouples were fixed on the inlet, middle and outlet of hollow core slab channel to read air hollow core temperatures along the hole . 2. fifteen thermocouples were fixed on the floor’s ceiling of the slab under the hole to read inlet, middle and outlet air surface slab temperatures. 3. twenty seven thermocouples were fixed inside the test room in three levels in order to read the air-conditioned space temperatures for room model. 4. one thermocouples are fixed at middle side slab in order to read side slab temperature. 5. the last thermocouple is for measuring the ambient air temperature. 2.3. method of testing two cases were taken in this work; the first case was with no external load (during the night period). the inlet air temperature, inlet velocity and internal load were varied in this case. the second case was done with 800 w/m² external load (during the day period) at a similar conditions for the first case. the measurement of the temperatures was taken every twenty minutes for the inlet air temperature through the slab. the slab surface temperature, the conditioned space temperatures and the slab side temperature were measured to study the performance of the termodeck system via the absorbed heat. according to the measurements, the performance for every case reaching the steady state in 90 to 150 minutes as a maximum. the measurements were taken for october 2013. the test room is located in a large laboratory (workshop) in university of karbala therefore the test room’s external environment is that of the test hall. the experimental cases are shown in table (1). wahid s. mohammad al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 13 24 (2014) 18 table 1, experimental test cases. 3. results and discussion general, the parameters that affect the thermal performance of the hollow core slabs are classified into four categories. two of these (diameter and thermal mass) are determined in the design stage of the slab and the other two (inlet air velocity and inlet air temperature) are determined in the operation stage. for the experiments carried out in this work, the temperature distributions were plotted for different parameters. the temperatures variation with time were drown using microsoft excel program and they show the effect of variations of the inlet air velocity and inlet air temperature to the slab with time. figures (5) to (15) represent unoccupied period at night time (without external load). two inlet air velocities were considered, i.e. (1 and 1.6 m/sec). figures (5) and (6) study the effect of inlet air velocity on the performance of this system. the flow in both cases is turbulent and a better air circulation is achieved with that air penetration in the room which leads to improve comfort. the results showed good heat removal achieved when the air inlet velocity is equal to (1m/s) with different external load, internal load and the supply core temperature. the termodeck system achieves good heat transfer between the incoming air and the concrete slab by ensuring good thermal coupling must exist between the air and the hollow cores of the building. this is achieved by using a core air velocity of approximately 1 m/s. so, the indoor thermal environment can meet the requirements at that ventilation rate. figures (7) to (14) represent the effect of inlet air temperature on the performance of this system. the results referred the reduction in the room temperature by about (5.4°c to 6.5°c) when the inlet air temperature is 16°c and about (2.5°c to 2.8°c) at the inlet air temperature of 18°c according to the change in the core air velocity and internal load. the slab surface temperature reduced by about (4.3°c to 5.6°c) when the inlet air temperature is 16°c and about 2.7°c at the inlet air temperature of 18°c. however, the slab side temperature reduced by about (3°c to 5°c). the steady state condition occurs during about 80 minutes for the cases without external load. figure (15) shows the variation of slab side temperature with time at different cases with internal load equal to 630 w/m 2 at various inlet parameters. all previous results confirm the effectiveness of the night ventilation strategy to remove heat from this system and obtaining high temperature drop at lower outdoor temperature. figures (16) to (23) represent the occupied period at the day time (with external load of 800 w/m 2 ). at inlet air velocity equal to 1m/sec the room temperature reduced from (38°c to 20°c) at inlet air temperature equal to 16°c and from (38°c to 23.5°c) at inlet air temperature of 18°c. however the room temperature reduced from (37.5°c to 22°c) at inlet air temperature equal to 16°c and from (37.5°c to 24.5°c) at the inlet temperature of 18°c for air velocity of 1.6 m/sec. no. of exp. inlet core velocity m/s inlet core temp. ºc ambient temp. ºc internal load w/m² external load w/m² 1 1 16 23.3 0 0 2 1.6 16 23.9 0 0 3 1 16 24.3 630 0 4 1.6 16 24.5 630 0 5 1 18 23.9 630 0 6 1.6 18 24.0 630 0 7 1 16 22.2 630 800 8 1.6 16 22.3 630 800 9 1 18 22.5 630 800 10 1.6 18 22.6 630 800 wahid s. mohammad al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 13 24 (2014) 19 similarity, with inlet air velocity equal to 1m/sec, the slab surface temperature reduced from (41°c to 21°c) at inlet air temperature equal to 16°c and from (41°c to 24.5°c) at inlet air temperature equal to 18°c. the slab surface temperature reduced from (41°c to 23.5°c) at inlet air temperature equal to 16°c and from (41°c to 26.5°c) at inlet air temperature equal to 18°c with inlet air velocity of 1.6 m/sec. finally the slab side temperature reduced about (11°c to 16°c) at various cases and the steady state condition occurs after approximately 140 minutes from starting point. figure (24), shows the variation of slab side temperature with time at various inlet conditions when external and internal load are equal to 800 and 630 w/m 2 respectively. fig. 5. variation of room temperature with time at tai = 16ºc without loads. fig. 6. variation of room temperature with time at tai = 16ºc without external load and the internal load = 630 w/m 2 . fig. 7. variation of room temperature with time at tai = 18ºc without external load and the internal load = 630 w/m 2 . fig. 8. variation of room temperature with time at uai = 1m/sec without external load and the internal load = 630 w/m 2 . fig. 9. variation of room temperature with time at uai = 1.6m/sec without external load and the internal load = 630 w/m 2 . 15 17 19 21 23 25 0 25 50 75 100 125 r o o m t em p . ( °c ) time (min) inlet velocity = 1 m/sec inlet velocity = 1.6 m/sec 15 17 19 21 23 25 0 25 50 75 100 125 150 r o o m t em p . ( °c ) time (min) inlet velocity = 1 m/sec inlet velocity = 1.6 m/sec 15 17 19 21 23 25 0 25 50 75 100 125 150 r o o m t em p . ( °c ) time (min) inlet velocity = 1 m/sec inlet velocity = 1.6 m/sec 15 17 19 21 23 25 0 25 50 75 100 125 150 r o o m t em p . ( °c ) time (min) inlet temp.= 16 ⁰c inlet temp.= 18 ⁰c 15 17 19 21 23 25 0 25 50 75 100 125 150 r o o m t em p . ( °c ) time (min) inlet temp.= 16 ⁰c inlet temp.= 18 ⁰c wahid s. mohammad al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 13 24 (2014) 20 fig. 10. variation of slab surface temperature with time at tai = 16ºc without loads. fig. 11. variation of slab surface temperature with time at tai = 16ºc without external load and the internal load equal to 630 w/m 2 . fig. 12. variation of slab surface temperature with time at tai = 18ºc without external load and the internal load = 630 w/m 2 . fig. 13. variation of slab surface temperature with time at uai = 1m/sec without external load and the internal load = 630 w/m 2 . fig. 14. variation of slab surface temperature with time at uai = 1.6m/sec without external load and the internal load = 630 w/m 2 . fig. 15. variation of slab side temperature with time without external load and the internal load equal to 630 w/m 2 . 15 17 19 21 23 25 0 25 50 75 100 125 150 s la b s u rf ac e te m p . ( °c ) time (min) inlet velocity = 1 m/sec inlet velocity = 1.6 m/sec 15 17 19 21 23 25 0 25 50 75 100 125 150 s la b s u rf ac e te m p . ( °c ) time (min) inlet velocity = 1 m/sec inlet velocity = 1.6 m/sec 15 17 19 21 23 25 0 25 50 75 100 125 150 s la b s u rf ac e te m p . ( °c ) time (min) inlet velocity = 1 m/sec inlet velocity = 1.6 m/sec 15 17 19 21 23 25 0 25 50 75 100 125 150 s la b s u rf ac e te m p . ( °c ) time (min) inlet temp.= 16 ⁰c inlet temp.= 18 ⁰c 15 17 19 21 23 25 0 25 50 75 100 125 150 s la b s u rf ac e te m p . ( °c ) time (min) inlet temp.= 16 ⁰c inlet temp.= 18 ⁰c 17 19 21 23 25 0 25 50 75 100 125 150 s id e sl ab t em p . ( ⁰c ) time (mins) inlet velocity = 1 m/sec , inlet temp. = 16 ⁰c inlet velocity = 1.6 m/sec , inlet temp. = 16 ⁰c inlet velocity = 1.6 m/sec , inlet temp. = 18 ⁰c inlet velocity = 1 m/sec , inlet temp. = 18 ⁰c wahid s. mohammad al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 13 24 (2014) 21 fig. 16. variation of room temperature with time at tai = 16ºc with external load= 800w/m2 and the internal load = 630 w/m 2 . fig. 17. variation of room temperature with time at tai = 18ºc with external load= 800w/m 2 and the internal load = 630 w/m 2 . fig. 18. variation of room temperature with time at uai = 1m/sec with external load= 800w/m 2 and the internal load = 630 w/m 2 . fig. 19. variation of room temperature with time at uai = 1.6m/sec with external load= 800w/m2 and the internal load = 630 w/m 2 . fig. 20. variation of slab surface temperature with time at tai = 16ºc with external load= 800w/m 2 and the internal load = 630 w/m 2 . fig. 21. variation of slab surface temperature with time at tai = 18ºc with external load= 800w/m 2 and the internal load = 630 w/m 2 . 5 10 15 20 25 30 35 40 0 50 100 150 200 250 300 350 r o o m t em p . (⁰ c ) time (mins) inlet velocity =1 m/sec inlet velocity =1.6 m/sec 5 10 15 20 25 30 35 40 0 50 100 150 200 250 300 350 r o o m t em p . ( ⁰c ) time (mins) inlet velocity =1 m/sec inlet velocity =1.6 m/sec 5 10 15 20 25 30 35 40 0 50 100 150 200 250 300 350 r o o m t em p . ( ⁰c ) time (mins) inlet temp. = 16 ⁰c inlet temp. = 18 ⁰c 5 10 15 20 25 30 35 40 0 50 100 150 200 250 300 350 r o o m t em p . ( ⁰c ) time (mins) inlet temp. = 16 ⁰c inlet temp. = 18 ⁰c 5 10 15 20 25 30 35 40 45 0 50 100 150 200 250 300 350 s la b s u rf ac e te m p . ( °c ) time (mins) inlet velocity =1 m/sec inlet velocity =1.6 m/sec 5 10 15 20 25 30 35 40 45 0 50 100 150 200 250 300 350 s la b s u rf ac e te m p . ( °c ) time (mins) inlet velocity =1 m/sec inlet velocity =1.6 m/sec wahid s. mohammad al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 13 24 (2014) 22 fig. 22. variation of slab surface temperature with time at uai = 1m/sec with external load = 800w/m 2 and the internal load = 630 w/m 2 . fig. 23. variation of slab surface temperature with time at uai = 1.6m/sec with external load= 800w/m 2 and the internal load = 630 w/m 2 . fig. 24. variation of slab side temperature with time at external load= 800w/m 2 and the internal load = 630 w/m 2 . 4. conclusions from the results of the present work, the following conclusions are deduced: 1. the experiments showed during load period that thermal comfort always can be achieved with inlet core temperatures between (18°c and 20°c) with air inlet velocity of 1m/s, for high external load of about 800w/m 2 . 2. the effect of air inlet velocity and air inlet temperature to the slab was very significant especially when the air inlet temperature decreases from (18°c to 16°c) and the results showed that the high heat removal take shorten time to reach to the steady state condition when tai=16°c and uai=1m/s. 3. the night ventilation strategy was found to be effective to remove heat in all present cases without loads if the outdoor temperature is lower than the indoor temperature . 4. applying the termodeck system with ventilation technique during the day or night times, was able to control the space condition, by cooling the ceiling of the building to remove the stored heat from the building. 5. this cooling technique is suitable for all the applications especially for buildings which need fresh air at all times as this system provide the buildings with treated (tempered) fresh air without any load on the capital cooling system. 5. references [1] raduzmeureanu and paul fazio, “thermal performance of a hollow core concrete floor system for passive cooling”, building and environment, volume (23), no. (3), pages (243–252), (1988). [2] fatemehsadatmirakbari, luisa brotas and fergus nicol, “ventilated hollow core slab; a low energy strategy to improve energy efficiency of the built environment”. architecture energy and sustainability, (2012). [3] brahamg.d., “passive air conditioning”, proceedings of the cibe national conference, canterbury, pages (1– 10), (1991). [4] shaw m.r., teadaway k.w., and willis, s.t.p., “effective use of building mass”,renewable energy, volume (5), no. (2), pages (1028-1038), (1994). 5 10 15 20 25 30 35 40 45 0 50 100 150 200 250 300 350 s la b s u rf ac e te m p . ( °c ) time (mins) inlet temp. = 16 ⁰c inlet temp. = 18 ⁰c 5 10 15 20 25 30 35 40 45 0 50 100 150 200 250 300 350 s la b s u rf ac e te m p . ( °c ) time (mins) inlet temp. = 16 ⁰c inlet temp. = 18 ⁰c 5 10 15 20 25 30 35 40 45 0 50 100 150 200 250 300 350 s la b s id e te m p . ( ⁰c ) time (mins) inlet velocity = 1 m/s , inlet temp. = 16 ⁰c inlet velocity = 1 m/s , inlet temp. = 18 ⁰c inlet velocity = 1.6 m/s , inlet temp. = 16 ⁰c inlet velocity = 1.6 m/s , inlet temp. = 18 ⁰c http://www.sciencedirect.com.tiger.sempertool.dk/science/article/pii/0360132388900091 http://www.sciencedirect.com.tiger.sempertool.dk/science/article/pii/0360132388900091 http://www.sciencedirect.com.tiger.sempertool.dk/science/article/pii/0360132388900091 wahid s. mohammad al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 13 24 (2014) 23 [5] barnaby ch.s., nall d.h. and dean ed., “structural mass cooling in a commercial building using hollow core concrete plank”, proc. national solar conference, amherst, ma, (1980). [6] standeven m., cohen r., bordas b. and leaman, a. probe 14: elizabeth fry building, building services journal, pages (37-42), (1998). [7] sebastian karlström, “analysis of thermally active ventilated hollow core concrete elements in a femlab environment compared to measurements”, division of building technology, school of architecture and the built environment, volume (34), pages (100-144), (2005). [8] ren m.j. and wright j.a., “a ventilated slab thermal storage system model”, building and environment, volume (33), no.(1), pages (43-52), (1998). [9] russell m.b., and surendranp.n., “influence of active heat sinks on fabric thermal storage in building mass”, applied energy, volume (70), pages (17-33), (2001). [10] bartonp., beggsc. b., and sleighp. a., “a theoretical study of the thermal performance of the termodeck hollow core slab system”, applied thermal engineering, volume (22), pages (14851499), (2002). [11] corgnati s.p., and kindinis a., “thermal mass activation by hollow core slab coupled with night ventilation to reduce summer cooling loads” ,building and environment, volume (42),pages (32853297), (2007). [12] xinhua xu a, jinghua yu a, shengwei wang b and jinbowanga, “research and application of active hollow core slabs in building systems for utilizing low energy sources”, applied energy, volume (116), pages (424–435), (2014). [13] chun k cheung and robert j fuller, advanced fabric energy storage system in australia, built environment research group, school of architecture and building, deakin university, (2007). (2014) 1324، صفحة 3، العدد10دجلة الخوارزمي الهندسية المجلم وحيد شاتي محمد 24 يطرة على الظروف الداخلية للبنايةللسّ التسخين األّولي /لتبريدل إستخدام نظام الترموَدك ار َعبْد أحَمد َحّمُودي **طالب كشاش مرتضى *دوحيد شاتي محمّ ***كـرَّ الجامعـة التكنولوجيـة/ قسم هندسة المكائن والمعدات ***،**،* wahid1953@yahoo.com: البريد االلكتروني* talib_km@yahoo.com ** االلكترونيالبريد: alkarnawi@yahoo.com: البريد االلكتروني*** الخالصة نموذج اأُجريَت التجارب على (. ترموديك)تم في هذا البحث اجراء دراسة عملية لتوزيع درجات الحرارة في حيّز مكيَّف بنظام تهوية البالطة المجوفة ( 59)تثبيت بوساطة توزيع درجات الحرارةتم قياس .(4\1)أساس مقياس رسم مناسب هو ، والذي بُنَِي على (1m1.2m1m)مصّغر لغرفة بأبعاد دون وجود حمل )أُخذت حالتان في هذا العمل ُصنِّفت على اساس عدم انشغال الحيز أي خالل فترة الليل . متعددةفي مناطق و مقاطع احراري ا مزدوج 800w/m)واالخرى خالل فترة النهار أي بوجود حمل خارجي مقداره ( خارجي 2 وفقا لحسابات الكسب الحراري الشمسي الناتج من االشعاع الشمسي ( التسخين في أجواء االقاليم الجافة لبساطتها واداءها /تائج أّكدت إستخدام نظام الترموديك ألغراض التهوية والتبريدجميع الن.خالل فصل الصيف في العراق .الجيد من حيث الراحة الحرارية وخزنها للطاقة و تحسين اداء الطاقة الكليّة للبنايةعن طريق تقليل الحمل االعظم this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 18, no. 4, december, (2022) p. p. 6072 bci-based smart room control using eeg signals oger zaya amanuel * yarub alazzawi ** *,**department of mechatronics engineering/ al-khwarizmi college of engineering/ university of baghdad *email: awkar.zia1202a@kecbu.uobaghdad.edu.iq **email: yaarub.omar@kecbu.uobaghdad.edu.iq (2022 september 26 2022; accepted uly j 42received ) https://doi.org/10.22153/kej.2022.09.004 abstract in this paper, we implement and examine a simulink model with electroencephalography (eeg) to control many actuators based on brain waves. this will be in great demand since it will be useful for certain individuals who are unable to access some control units that need direct contact with humans. in the beginning, ten volunteers of a wide range of (2066) participated in this study, and the statistical measurements were first calculated for all eight channels. then the number of channels was reduced by half according to the activation of brain regions within the utilized protocol and the processing time also decreased. consequently, four of the participants (three males and one female) were chosen to examine the simulink model during different actions. the model contained: input signals, data selection according to the activation regions in the brain, features extraction, classification according to the frequency ranges of each action, and an interface with an embedded system to control the actuators. keywords: eeg, bci, fft. 1. introduction the brain-computer interface-based systems are being used in a variety of applications, such as motor disabilities' needs, games, and other scientific domains that are related to the brain. through the bci, eeg signals have been used to manage external equipment. these systems allow disabled patients to operate a variety of equipment using their brain waves. also, the brain-computer interface (bci) is a tool capable of converting a user's brainwave patterns into computer-readable messages. besides, brain activity may be studied using electroencephalography (eeg) by placing electrodes on the scalp to measure brain activity. it is viable, flexible, portable, and can analyze brain interactions in real-time [1] [2] [3] [4] [5]. eeg measures the brain activity and divides it into rhythms depending on the frequency: delta𝛿 (< 4 hz), theta-𝜃 (4-8) hz, alpha-𝛼 (8-13) hz, beta-𝛽(13-32) hz, and gamma-𝛾 (> 32) hz [5] [6]. many previous studies focused on the classification of brain waves and controlling some devices using the simulink model. [7] used bci with simulink to classify the signals [8]. described how to control three servo motors (robotic arms) based on brain waves [9]. showed the control of an actuator or computer cursor using the simulink framework [10]. explained the analysis and classification of eeg signals using the simulink model. this study involved a large number of participants with a wide range of ages (20-65) years old, giving more information about the data and obtaining more accurate results. moreover, the statistical measurements were calculated and enhanced. besides, it was suggested to reduce the number of channels needed according to the used protocol and the activation of brain lobes’ regions. consequently, the model was examined by four mailto:awkar.zia1202a@kecbu.uobaghdad.edu.iq mailto:yaarub.omar@kecbu.uobaghdad.edu.iq https://doi.org/10.22153/kej.2022.09.004 oger zaya amanuel al-khwarizmi engineering journal, vol. 18, no. 4, p.p. 6072 (2022) 61 participants (28-38) years old, and all attempts were successful. 2. experimental work the eeg electrodes were positioned as a 10–20 system [6], as shown in figure (1), and the ultracortex mark iv headset (16 channels), shown in figure (2), was used for brain wave collection. the collected signals were sent by the cyton board to the computer via usb dongle. fig. 1. 10-20 system of electrodes placement. fig. 2. ultra-cortex mark iv headset with the components. oger zaya amanuel al-khwarizmi engineering journal, vol. 18, no. 4, p.p. 6072 (2022) 62 the headset includes dry eeg sensors and the pic-32mx250f128b microcontroller in its design, which provides relatively abundant memory and great processing performance. in addition, the chip-kittm bootloader and the most modern open-bci firmware are already implemented on the board. as well, the system interacts wirelessly with a computer using an rfduino radio module and usb dongle via ble, as shown in figure (3). finally, each channel is recorded at a 125 or 250 hz sampling rate [11] [12] [13]. 3. methodology in this work, 10 people participated in signals collection, (9 males and 1 female) aged (20-65) years old, as shown in table (1). the participants were recruited from inside and outside al khwarizmi college of engineering at baghdad university to be volunteers to collect their eeg signals. moreover, all received proper consent under an approved protocol from al-khwarizmi college of engineering/mechatronics department. the following protocol, shown in figure (4), was contained in three sessions as following: (open eyes and relaxed), (closed eyes and relaxed) and then (open eyes with concentration and calculate a simple arithmetic mental). each session was followed by a few seconds of rest. in addition, the signals were collected without smoothing, a notch filter (50 hz), and a band pass filter (1-100 hz). fig. 4. the protocol of eeg signals collection. fig. 3. the communication between the cyton boards and computer oger zaya amanuel al-khwarizmi engineering journal, vol. 18, no. 4, p.p. 6072 (2022) 63 table 1, the volunteers’ information. first, eight eeg channels were utilized in the signals’ collection for each person. the statistical measurements (mean and standard deviation) were calculated as shown in figure (5), and it was noticed that an overlap occurred between the regions in the close and open classes, as shown in table (2). then, depending on the used protocol (open and closed eyes), the alpha and beta rhythms are activated mainly, which are mostly recognized in frontal and occipital regions, because the alpha waves occur while resting with the eyes closed, and the frequency of the rhythm is (8-13) hz. it is measured in the rear of the skull (occipital), while beta waves are detected in the front central regions of the scalp [14]. moreover, when the eyes are opened or mental activity begins, the alpha waves diminish and are replaced by beta waves. fig. 5. the mean and standard deviation of 8 channels. table 2, the mean values for all channels accordingly, only the four channels were utilized in this study (fp1 and fp2 for the frontal lobe and o1 and o2 for the occipital lobe) [15] [16]. the statistical measurements were recalculated as shown in figure (6), which indicated that the mean values for the open eyes class (positive) were separated from those for the closed eyes class (negative), as shown in table (3). participant gender age status 1 male 20 healthy 2 female 28 healthy 3 male 29 healthy 4 male 37 healthy 5 male 35 healthy 6 male 46 healthy 7 male 41 healthy 8 male 43 healthy 9 male 60 healthy 10 male 65 healthy participant mean closed eyes class open eyes class 1. -3.0048e+04 -2.5600e+04 2. -9.9268e+03 2.4977e+03 3. 5.5503e+03 -9.5832e+04 4. -7.4672e+04 8.6425e+04 5. -8.8025e+04 -7.6606e+03 6. -2.5069e+03 -3.0630e+04 7. -5.6147e+04 -6.4567e+04 8. -4.6553e+04 -1.0848e+05 9. -5.0164e+04 -7.1173e+04 10. 2.7355e+04 1.7761e+04 oger zaya amanuel al-khwarizmi engineering journal, vol. 18, no. 4, p.p. 6072 (2022) 64 fig. 6. the mean and standard deviation of frontal and occipital channels only. table 3, the mean values for the frontal and occipital regions’ channels the four channels selected (fp1, fp2, o1 and o2) were plotted as shown in figure (7), using eeglab (scale 1000). eeglab is mostly used for visualizing or plotting the signals and removing the artifacts [17]. then a band pass filter (7–32) hz was used for the same channels depending on the frequency ranges of alpha (8–13) hz and beta (14–32) hz rhythms, as presented in figure (8). fig.7. the frontal and occipital channels without filtering. participant mean closed eyes class (o1&o2) channels open eyes class (fp1 & fp2) channels 1. -4.6899e+04 1.2860e+04 2. -1.5007e+05 7.5808e+03 3. -3.8224e+04 7.7577e+03 4. -5.3868e+04 9.3905e+03 5. -5.3995e+04 8.6892e+03 6. -3.3575e+04 9.2576e+03 7. -1.9006e+04 5.8581e+03 8. -3.0794e+04 7.0939e+03 9. -3.5690e+04 8.7793e+03 10. -4.3787e+04 6.1779e+03 oger zaya amanuel al-khwarizmi engineering journal, vol. 18, no. 4, p.p. 6072 (2022) 65 fig. 8. the frontal and occipital channels with filtering. 4. pre-processing first, the collected signals are amplified many times before being transmitted to the computer via the cyton board, bio-sensing daisy board, and usb dongle. then the notch filter is applied, which is used to remove a specific frequency [16], so the filter was applied for 50 hz because that hertz is the type of activity in the ac current source of the electrical equipment. as well, a band-pass filter (1100) hz is applied to remove the other unwanted frequencies. moreover, the data is sampled at 250 hz on each channel. finally, some epochs (transient time) are removed from each session to avoid the overlap between the classes. 5. simulation model figure (9) illustrates the steps that were followed, beginning with collecting brain waves using the electrodes that were placed in the headset. then select the data according to the used protocol, which causes the activation in the frontal and occipital lobes. therefore, the number of channels is reduced from 8 to 4 (2 for the frontal lobe region and 2 for the occipital lobe region). consequently, the data was mapped to features during the feature extraction step. after that, the features are classified into classes within the classification. finally, the classified classes control the actuators (dc motors were used to indicate the room devices) via an embedded system, which receives the conditions and commands based on brain waves. fig. 9. the block diagram. oger zaya amanuel al-khwarizmi engineering journal, vol. 18, no. 4, p.p. 6072 (2022) 66 in this work, matlab simulink was used to build a model that was capable of reading raw data, selecting specific channels, extracting features, classifying them, and controlling the actuators using an interface with a microcontroller. in other words, for a new participant, first the collected signals in different actions according to a specific protocol enter the model. then divide the data into some segments, which are translated into features that are classified into two decisions. the decisions are: if the data belong to the closed-eyes class, then the first motor turns on. whereas if the data belong to the open eyes class, the second motor turns on, as shown in figure (10). fig.10. the simulink model. the blocks used in the simulation model were as follows: the (simin) block was used to enter the collected signals into the simulink model. the dwt (discrete-wavelet-transform) block was used to separate a signal into smaller bandwidth sub-bands and lower sampling rates [18]. it includes a variety of filters (haar, daubechies, symlets, coiflets, biorthogonal, and other types), as well as symmetric and asymmetric tree structures. moreover, the fft block was used as a feature extraction block with the periodogrammethod. consequently, a nonparametric approximation of the spectrum is computed, and the output is equal 𝑦 = 𝑎𝑏𝑠 (𝑓𝑓𝑡(𝑢, 𝑛𝑓𝑓𝑡)) … (1) where 𝑢: is an input 𝑀 𝑏𝑦 𝑁 in addition, in the classification step, a digital filter design block was used to implement a digital fir or iir filter or other digital filters. these filters can classify the signals into many bands according to the frequency range, and as the utilized protocol, there were two classes that are different in the frequency range. first, closed eyes class (alpha rhythm) 7-14 hz. second, open eyes with a simple mental (beta rhythm) 14-32 hz. finally, the digital pin block and pwm block were used to interface the simulink with a micro-controller to control the actuators, and if the new data is classified as first class, the 1st motor turns on, while if the data is classified as second class, the 2nd motor turns on, as shown in figure (11). oger zaya amanuel al-khwarizmi engineering journal, vol. 18, no. 4, p.p. 6072 (2022) 67 fig.11. the flow chart of the work 6. results and discussion the data was collected from ten participants of different ages (20-66) years old, and the statistical measurements (mean and standard deviation) were calculated for eight and four channels, respectively. then four participants (three males, one female) aged (28–38) years old were chosen to examine the simulink model. their brain waves were translated as features using fast fourier transform (fft) and classified into sub-bands based on the frequency range using band-pass filters according to the participant’s status. figure (12), depicts the frequency and power spectrum density (psd) for the frontal and occipital regions (open eyes with arithmetic and closed eyes with relaxation). in addition, the psd is one of the most significant digital-processing tools. it assists in understanding how a signal's intensity is dispersed in the frequency domain [19]. oger zaya amanuel al-khwarizmi engineering journal, vol. 18, no. 4, p.p. 6072 (2022) 68 fig. 12. frequency and psd for fp1, fp2, o1, and o2 channels. figure (13), presents the two actuators which were turning on/off based on the participant’s brain waves. the two actuators were connected to a microcontroller (arduino) through a driver, and the microcontroller was interfaced with matlab to receive the commands based on the simulation model. moreover, the attempts to examine the model and turn on/off the actuators based on brain waves were successful. oger zaya amanuel al-khwarizmi engineering journal, vol. 18, no. 4, p.p. 6072 (2022) 69 fig. 13. the hardware circuit. 7. conclusion this study proposed a simulation model to control a smart structure, such as simple actuators, depending on brain waves. ten volunteers participated in collecting the brain waves using electroencephalography (eeg) and non-invasive bci. first, the statistical measurements for all channels (eight channels) were calculated, and there was an overlap between the results for the two different classes (closed eyes and open eyes with mental activity). then, depending on the activation of brain lobes’ regions according to the used protocol, the statistical measurements are recalculated and enhanced. besides, the number of used channels was reduced to four channels only (two channels for the occipital lobe that is activated when the participant is relaxed and the eyes are closed) and (two channels for the frontal lobe that is activated when the eyes are open or during concentrating on a specific task or beginning a simple mental activity. accordingly, we built a simulation model that contains the following: input of the collected signals, dividing into sub-bands, mapping the data into the frequency domain using the fft algorithm and extracting features, classifying the data into different classes by using digital filters according to the frequency ranges for each action, and turning on/off the actuators using an interface between the simulink model and a microcontroller as an embedded system. moreover, the model was examined by four participants as follows: they input their collected signals, divide the signals into sub-bands, map the data into the frequency domain and extract features, and classify them into class 1 (relax and closed eyes) or class 2 (open eyes with mental activity). consequently, the actuators were turned on and off, and all experiments succeeded. the significance of this work on the clinical side will be of importance to those who have disabilities, like older people who cannot open doors and windows, or even move from their spot, and are suffering from the normal activities of normal life. in addition, this work could be modified by using artificial intelligence, such as machine learning algorithms, and be used by different kinds of people, with or without a disorder, like those who are unable to access the control units. oger zaya amanuel al-khwarizmi engineering journal, vol. 18, no. 4, p.p. 6072 (2022) 70 table 4, related work acknowledgements we would like to express our thanks to the biomedical engineering department at alkhwarizmi college of engineering, especially dr. noor kamal al-qazzaz, for their guidance and assistance. 8. references [1] s. abdulkader, a. atia and m. mostafa, "brain computer interfacing: applications and challenges," egyptian informatics journal, vol. 16, pp. 213--230, 2015. [2] r. ramadan, s. refat, m. elshahed and r. ali, basics of brain computer interface, springer, 2015, pp. 31--50. [3] r. ramadan and a. vasilakos, "brain computer interface: control signals review," neurocomputing, vol. 223, pp. 26--44, 2017. [4] f. lotte, l. bougrain and m. clerc, "electroencephalography (eeg)-based brain-computer interfaces," wiley encyclopedia of electrical and electronics engineering, p. 44, 2015. [5] j. wolpaw, n. birbaumer, d. mcfarland, g. pfurtscheller and t. vaughan, "braincomputer interfaces for communication and control," clinical neurophysiology, vol. 113, pp. 767--791, 2002. [6] p. abhang, b. gawali and s. mehrotra, "technological basics of eeg recording and operation of apparatus," introduction to eeg-and speech-based emotion recognition, pp. 19--50, 2016. [7] v. rohith, t. prajitha and s. suresh, "eeg signal analyzing and simulation under computerized technological support," international journal of engineering and technology (uae), vol. 7, pp. 38--41, 2018. [8] p. pelayo, h. murthy and k. george, "braincomputer interface controlled robotic arm to improve quality of life," in 2018 ieee international conference on healthcare informatics (ichi), ieee, 2018, pp. 398-399. [9] m. y, k. djouani and k. anish, "a matlab/simulink framework for real time implementation of endogenous brain computer interfaces," in 2017 ieee africon, ieee, 2017, pp. 100--105. study eeg signals collection subjects feature extraction classification controlled applications [7] eeg database in internet wavelet transform (mean, median, std, min and max) sub-band depending on frequency range [8] openbci ultra-cortex 3 fft ssvep (three sets of leds to distinguish between the degrees of freedom) servo motors [9] electrocap kit 5 / (26 ±2.5) years old fft mars, ann computer cursor [10] 1 psd and |𝐹𝐹𝑇|2 digital filters this study ultra-cortex mark-iv 10 / (20-66) years old and 4 (3 males and 1 female) / (28-38) years old for examining the model. fft filters depending on the frequency of each action dc motors this study involved a larger number of participants with a wide range of ages (20-65) years old, giving more information about the data and obtaining more accurate results. moreover, the statistical measurements were calculated and enhanced. besides, it was suggested to reduce the number of channels needed according to the used protocol and the activation of brain lobes’ regions. oger zaya amanuel al-khwarizmi engineering journal, vol. 18, no. 4, p.p. 6072 (2022) 71 [10] g. phan, "analysis and processing emg signals using simulink," turkish journal of computer and mathematics education (turcomat), vol. 12, pp. 7055--7060, 2021. [11] m. menteş, s. özbal and g. ertaş, "experiences on 3d printing of an eeg headset," in 2021 medical technologies congress (tiptekno), ieee, 2021, pp. 1-4. [12] v. shivappa, b. luu, m. solis and k. george, "home automation system using brain computer interface paradigm based on auditory selection attention," in 2018 ieee international instrumentation and measurement technology conference (i2mtc), ieee, 2018, pp. 1--6. [13] a. rajavenkatanarayanan, "human factors analysis and monitoring to enhance humanrobot collaboration," ph.d. dissertation, university of texas at arlington, 2021. [14] j. moini and p. piran, functional and clinical neuroanatomy: a guide for health care professionals, academic press, 2020, pp. 177--190. [15] n. al-qazzaz, m. sabir, s. ali, s. ahmad and k. grammer, "effective eeg channels for emotion identification over the brain regions using differential evolution algorithm," in 2019 41st annual international conference of the ieee engineering in medicine and biology society (embc), ieee, 2019, pp. 4703--4706. [16] s. jaafer, "hurst exponent and tsallis entropy markers for epileptic detection from children," al-khwarizmi engineering journal, vol. 17, p. 34–42, 2021. [17] m. asogbon, o. samuel, x. li, n. jiang, o. idowu, y. jiang, y. geng, a. al-timemy and g. li, "a robust multi-channel eeg signals preprocessing method for enhanced upper extremity motor imagery decoding," in 2020 ieee international conference on mechatronics and automation (icma), 2020, pp. 1929-1934. [18] a. almahdi, a. yaseen and a. dakhil, "eeg signals analysis for epileptic seizure detection using dwt method with svm and knn classifiers," iraqi journal of science, no. 2, p. 54–62, 2021. [19] s. valipour, a. shaligram and g. kulkarni, "detection of an alpha rhythm of eeg signal based on eeglab," int j eng res appl, vol. 4, pp. 154--159, 2014. (2022) 60-72، صفحة 4، العدد18مجلة الخوارزمي الهندسية المجلد اوكر زيا عمانوئيل 72 غرفة للتحكم بدماغ للالكهربائية شارات االاستنادا الى ربط البيني بين الدماغ والحاسوب النظام ذكية **يعرب العزاوي *اوكر زيا عمانوئيل د*،** قسم هندسة الميكاترونكس/ كلية الهندسة الخوارزمي/ جامعة بغدا awkar.zia1202a@kecbu.uobaghdad.edu.iq*البريد االلكتروني: yaarub.omar@kecbu.uobaghdad.edu.iq**البريد االلكتروني: الخالصة ( للتحكم في العديد من المحركات بناًء على موجات الدماغ. eegمن الربط البيني باستخدام تخطيط كهربية الدماغ ) تنفيذ وفحص نموذجتم بحثال افي هذ مباشر مع يكون مفيدًا لبعض األفراد غير القادرين على الوصول إلى بعض وحدات التحكم التي تحتاج إلى اتصال هذا النوع من الدراسات يعتبر مهم النه ( عاًما، وتم حساب القياسات اإلحصائية أوالً لجميع القنوات الثمانية. ثم تم 66-20) أعمارهم كانت شارك في هذه الدراسة عشرة متطوعيناية البشر. في البد ، تم اختيار أربعة من عد ذلك. وبايضا ، كما انخفض وقت المعالجةالبروتوكول المستخدم وحسبمناطق الدماغ نشاطتقليل عدد القنوات إلى النصف وفقًا ل مختلفة.خالل نشاطات نموذج الالمشاركين )ثالثة ذكور وأنثى واحدة( لفحص والتصنيف وفقًا لنطاقات المناسبة او المواصفات واستخراج الميزاتفي الدماغ نشاطاحتوى النموذج على: إشارات اإلدخال واختيار البيانات وفقًا لمناطق ال .او المحركات نظام مدمج للتحكم في المشغالت التعامل مع مسيطر او ومن ثم التردد لكل إجراء mailto:awkar.zia1202a@kecbu.uobaghdad.edu.iq mailto:yaarub.omar@kecbu.uobaghdad.edu.iq 8. references al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 4, no. 3, pp 3442 (2008) fractally generated microstrip bandpass filter designs based on dual-mode square ring resonator for wireless communication systems jawad k. ali department of electrical and electronic engineering/ university of technology p.o. box 35239, baghdad, iraq, email: jawengin@yahoo.com (received 10 march 2008; accepted 2 september 2008) abstract a novel fractal design scheme has been introduced in this paper to generate microstrip bandpass filter designs with miniaturized sizes for wireless applications. the presented fractal scheme is based on minkowski-like prefractal geometry. the space-filling property and self-similarity of this fractal geometry has found to produce reduced size symmetrical structures corresponding to the successive iteration levels. the resulting filter designs are with sizes suitable for use in modern wireless communication systems. the performance of each of the generated bandpass filter structures up to the 2nd iteration has been analyzed using a method of moments (mom) based software ie3d, which is widely adopted in microwave research and industry. results show that these filters possess good transmission and return loss characteristics, besides the miniaturized sizes meeting the design specifications of most of wireless communication systems. keywords: microstrip bandpass filter (bpf), filter miniaturization, dual-mode resonator, square ring resonator. 1. introduction since the pioneer work of mandelbrot [1], the fractal geometry has found extensive applications in almost all the fields of science. among these fields are the physical and engineering applications. in electromagnetics, fractal geometry has been applied widely in the fields of antenna and passive microwave circuit design, due the fantastic results gained in the miniaturization and performance as well. different from euclidean geometries, fractal geometries have two common properties, spacefilling and self-similarity. it has been shown that the self-similarity property of fractal shapes can be successfully applied to the design of multiband fractal antennas, such as the sierpinski gasket antenna, while the space-filling property of fractals can be utilized to reduce antenna size. fractal curves are well known for their unique space-filling properties. research results showed that, due to the increase of the overall length of the microstrip line on a given substrate area as well as to the specific line geometry, using fractal curves reduces resonant frequency of microstrip resonators, and gives narrows resonant peaks. most of the research efforts has been devoted to the antenna applications. in passive microwave design, the research is still limited to few works and is slowly growing. among the earliest predictions of the use of fractals in the design and fabrication of filters is that of yordanov et.al, [2]. their predictions are based on their investigation of cantor fractal geometry. however, recent development in wireless communication systems has presented new challenges to design and produce high-quality miniaturized components. these challenges stimulate microwave circuits designers and antennas designers to seek out for solutions by investigating different fractal geometries [3-7]. hilbert fractal curve has been used as a defected ground structure in the design of a microstrip lowpass filter operating at the l-band microwave frequency [3]. mailto:jawengin@yahoo.com jawad k. ali al-khwarizmi engineering journal, vol. 4, no. 3, pp 34-42 (2008) 35 sierpinski fractal geometry has been used in the implementation of a complementary split ring resonator [4]. split ring geometry using square sierpinski fractal curves has been proposed to reduce resonant frequency of the structure and achieve improved frequency selectivity in the resonator performance. koch fractal shape is applied to mm-wave microstrip band pass filters integrated on a highresistivity si substrate. results showed that the 2nd harmonic of fractal shape filters can be suppressed as the fractal factor increases, while maintaining the physical size of the resulting filter design [5]. in this paper, a new fractal scheme, based on minkowski-like prefractal geometry, is presented to produce successive design geometries for the dual-mode microstrip bandpass filter based on the conventional dual-mode square ring resonator as a starting step. the resulting filters are supposed to have miniaturized sizes with adequate reflection and transmission responses. 2. the proposed fractal scheme the starting pattern for the proposed bandpass filter as a fractal is the square ring with a side length lo, fig1b. from this starting pattern, each of its four sides is replaced by what is called the generator structure shown in fig1a. to demonstrate the fractal generation process, the first two iterations are shown. the first iteration of replacing a segment with the generator is shown in fig. 1c. the starting pattern is euclidean and, therefore, the process of replacing the segment with the generator constitutes the first iteration. the generator is scaled after, such that the endpoints of the generator are exactly the same as the starting line segment. in the generation of the true fractal, the process of replacing every segment with the generator has been carried out an infinite number of times. the generator is composed of five segments .the middle segment, w1, is chosen such that it is with shorter length than the two end segments. the other two vertical segments are tuned to adjust the overall perimeter of the fractal length. this tuning length is called the indentation width, w2 [8]. the resulting prefractal structure has the characteristic that the perimeter increases to infinity while maintaining the volume occupied. this increase in length decreases the required volume occupied for the pre-fractal bandpass filter at resonance. it has been found that: …(1) where pn is the perimeter of the nth iteration prefractal and a2 is the ratio w2/lo. theoretically as n goes to infinity the perimeter goes to infinity. the ability of the resulting structure to increase its perimeter at every iteration was found very triggering for examining its size reduction capability as a microstrip bandpass filter. the basic idea to propose a fractal technique to generate a miniaturized microstrip bandpass filter structures has been borrowed from the successful application of such a technique in the microstrip antenna design, where compact size and multi-band behavior have been produced due to the space-filling and self-similarity properties of the resulting microstrip fractal antenna design [9,10]. it has been concluded in antenna design, that the number of generating iterations required to make use of the benefits of miniaturization is only few before the additional complexities become indistinguishable [8.9]. this is right in this field, since the antenna aperture when much reduced leads to less gain though the radiation performance is still attractive. however, this cannot be as serious in the filter design unless practical limitations obscure its implementation due to fabrication tolerances. practically, shape modification of the resulting structures in figs. (1c and 1d) is a way to increase the surface current path length compared with that of the conventional square ring resonator, fig. 1b; resulting in a reduced resonant frequency or a reduced resonator size, if the design frequency is to maintained. the space filling geometry and the self similarity that the 1 st iteration structure in fig. 1c possesses, make it analogous to the modified square microstrip antenna reported in the literature [11,12]. it is expected then, that the 2 nd iteration, shown in fig. 1d will exhibit further miniaturization ability owing to its extra space filling property. theoretically the size reduction process goes on further as the iteration steps increase. an additional property that the presented scheme possesses is the symmetry of the whole structure in each of the iteration levels about its diagonal. this property is of special importance in the design of dual-mode loop resonators [13,14]. the length lo of the conventional microstrip dual-mode square ring resonator has been determined using the classical design equations reported in the literatures [13-15] for a specified value of the operating frequency and given substrate properties. this length represents a slightly less than quarter the guided wavelength at its fundamental resonant frequency in the resonator. jawad k. ali al-khwarizmi engineering journal, vol. 4, no. 3, pp 34-42 (2008) 36 as shown in fig. 1, applying geometric transformation of the generating structure (fig. 1a) on the square ring resonator (fig. 1b), results in filter structure depicted in (fig. 1c). similarly successive bandpass filter shapes, corresponding to the following iterations can be produced as successive transformations have been applied. at the n th iteration, the corresponding filter side length, ln has been found to be: …(2) while the enclosing area, an, has been found to be: …(3) where ao is the area occupied by the conventional square ring resonator. the dimension of a fractal provides a description of how much it efficiently fills a space. it is a measure of the prominence of the irregularities when viewed at very small scales [16, 17]. a dimension contains much information about the geometrical properties of a fractal. according to falconer [16], since the generator used to develop the proposed fractal structure involves similarity transformations of more than one ratio; a1 and a2, the dimension of the 2 nd iteration structure can be obtained from the solution of the following equation: …(4) where d, represents the dimension, a1 is the ratio w1/lo, and a2 is as defined earlier. then the dimension of the proposed structure, according to equ (4) is equal to 1.586.this value of dimension has been obtained for values of a1 = 0.05 and a2 = 0.35. it is worth to mention here, the dimension of traditional minkowski island fractal, according to equ. (4), is equal to 1.465, where in such a case, a1 and a2 are both equal to one-third. 3. filter designs three microstrip dual-mode bandpass filter structures corresponding to the zero, 1 st , and the 2 nd iterations have been designed for the ism band applications at the design frequency of 2.4 ghz. it has been supposed that these filter structures have been etched using a substrate with a dielectric constant of 10.8 and thickness of 1.27 mm. at first, the side length of the square ring resonator, lo, has to be calculated as [13-15]: …(5) where λgo is the guided wavelength .then the side length, ln, for the successive iterations can be calculated, based on the value of ln, using eqn (2). note that a small perturbation has been applied to each dual-mode resonator at a location that is assumed at a 45° offset from its two orthogonal modes. this perturbation is in the form of a small patch is added to the square ring, and the other subsequent iterations loop resonators. it should be mentioned that for coupling of the orthogonal modes, the perturbations could also take forms other than this shape. but since the resulting resonators are characterized by their diagonal symmetry, this shape of perturbation is the most convenient to satisfy the required coupling. the effect of the perturbation size on the dual-mode ring resonator filter performance curves is beyond the scope of this paper; since the main aim is to present a new technique for generating miniaturized bandpass filter design based on a fractal iteration process. the dimensions of the perturbations of each filter must be tuned for the required filter performance, since the nature and the strength of the coupling between the two degenerate modes of the dualmode resonator are mainly determined by the perturbation’s size and shape. however, extensive details about this subject can be found in [18,19]. slight tuning of the initially calculated value of lo is necessary to be adjusted to the design frequency. figs (2-3) show the layouts of the resulting dual-band bandpass filters and table 1 summarizes their side lengths and the satisfied size reduction percentages as compared with the conventional square ring resonator. it is expected that the 3 rd and the 4 th iterations bandpass filter structures may satisfy further size reductions of about 72% and 78% respectively, if the fabrication tolerances permits to be implemented. table 1 summary of the dimensions, and the size reduction satisfied of the generated filters. filter type parameters squ. ring 1st iter. 2nd iter. side length, mm calc. 13.50 10.45 8.10 sim. 13.07 10.24 8.00 occupied area, mm2 calc. 182.25 109.2 65.61 sim. 170.95 104.85 64.00 size reduction calc. ---40.1% 64.0% sim. ---38.7% 62.6% it is worth to mention that, the microstrip bandpass filter based on the 1 st iteration depicted in fig (3), has a similar structure with that reported in [20]. in [20], the presented filter jawad k. ali al-khwarizmi engineering journal, vol. 4, no. 3, pp 34-42 (2008) 37 structure represents a technique to produce a size reduction of the conventional dual-mode square ring by modifying its shape. this technique has stopped at a single step and does not goes further; hence it can be regarded as just a single intermediate step in the more general technique presented in this paper. the microstrip bandpass filter based on the 2 nd iteration depicted in fig (4) is similar in structure with that presented by [21]. again, the presented filter structure can be considered as a single intermediate step in the fractal based technique presented in this paper, since it has neither based on predefined step nor it has any further extension. 4. performance evaluation filter structures, depicted in figs.2 to 4, have been modeled and analyzed at an operating frequency, in the ism band, of 2.4 ghz using the ie3d electromagnetic simulator from zeland software inc. this simulator performs electromagnetic analysis using the method of moments (mom). the corresponding simulation results of return loss and transmission responses of these filters are shown in figs.5 to7 respectively. figs. 6 and 7, imply that the resulting prefractal bandpass filters offer adequate performance curves as those for the conventional dual-mode square ring resonator, fig.5. as can be seen, all of the filter responses show two transmission zeros symmetrically located around the deign frequency. however, these responses and their consequent poles and zeros could be, to a certain extent, controlled through the variation of the perturbation dimensions and/or the input/output coupling techniques used. figs8 to 10 shows the current density patterns using the em simulator for 2 nd iteration dual-mode microstrip bandpass filter at the design frequency and other two frequencies around it. it clear from these figures that only at the design frequency the two degenerate modes are excited and coupled to each other leading to the required filter performance, while at the other two frequencies, no degenerate mode are excited as expected at all. in these figures, the same color code is used as an indication for the current densities. the previous filter designs can easily be scaled to other frequencies required for other wireless communication systems. in this case, the resulting new filter will be of lager or smaller in size according to the frequency requirements of the specified applications. 5. conclusions in this paper, a novel fractal design scheme has been presented as a new technique for microstrip bandpass filter design based on dualmode square ring resonator. due to the spacefilling property the presented fractal possess, the resulting filter designs have proven to be more compact in size as the iteration process goes on. this makes them appropriate for use in modern mobile communication systems, where the miniaturized size becomes a critical requirement. up to the 2 nd iteration, microstrip bandpass filters have been designed according to the presented technique and analyzed using the method of moments (mom) at the ism frequency band. simulation results show that these filters possess reasonable return loss and transmission performance responses. microstrip bandpass filters designs based on the 1 st and 2 nd iterations have shown size reductions of about 40% and 64% as compared with the conventional microstrip square ring bandpass filter designed at the same frequency and using the same substrate material. as the practical fabrication tolerances may permit, it is expected that the 3 rd iteration and 4 th iteration filter structures will offer further size reductions of about 72% and 78% respectively, as predicted by the presented fractal scheme. the proposed technique can be generalized as a flexible design tool for compact microstrip bandpass filters for a wide variety of wireless communication systems. jawad k. ali al-khwarizmi engineering journal, vol. 4, no. 3, pp 34-42 (2008) 38 fig. 1. the generation process of the minkowski-like prefractal structure. (a) the generator. (b) the square ring resonator. (c) the 1 st iteration, and (d) the 2 nd iteration. fig. 2. the layout of the dual-mode square ring resonator, (the intiation). fig. 3. the layout of the dual-mode microstrip bandpass fiber base on the 1 st iteration. fig. 4. the layout of the dual-mode microstrip bandpass filter base on the 2 nd iteration. jawad k. ali al-khwarizmi engineering journal, vol. 4, no. 3, pp 34-42 (2008) 39 fig. 5. the return loss and transmission responses of the dual-band microstrip square ring resonator. fig. 6. the return loss and transmission response of the dual-band microstrip 1 st iteration bandpass filter. fig. 7. the return loss and transmision response of the dual-band microstrip 2 nd iteration bandpass filter. jawad k. ali al-khwarizmi engineering journal, vol. 4, no. 3, pp 34-42 (2008) 40 fig. 8. current density distribution at the surface of the 2 nd iteration microstrip bandpass filter simulated at 2.4 ghz resonance frequency. fig. 9. current density distribution at the surface of the 2 nd iteration microstrip bandpass filter simulated at a frequency of 2.3 ghz. fig. 10. current density distribution at the surface of the 2 nd iteration microstrip bandpass filter simulated at a frequency of 2.5 ghz. jawad k. ali al-khwarizmi engineering journal, vol. 4, no. 3, pp 34-42 (2008) 41 6. references [1] b. b. mandelbrot, “the fractal geometry of nature,” w. h. freeman and company, 1983. [2] o. i. yordanov, et.al, “properties of fractal filters and reflectors,” iscap91, seventh international conference, pp.698-700, 1991. [3] j. chen, z. b. weng, y. c. jiao and f. s. zhang, “lowpass filter design of hilbert curve ring defected ground structure,” progress in electromagnetics research, pier 70, pp. 269–280, 2007. [4] v. crnojevic-bengin, v. radonic, and b. jokanovic, “complementary split ring resonators using square sierpinski fractal curves,” proceedings of the 36th european microwave conference, pp.1333-1335, sept. 2006, manchester, uk. [5] i. k. kim, et.al, “koch fractal shape microstrip bandpass filters on high resistivity silicon for the suppression of the 2nd harmonic,” journal of the korean electromagnetic engineering society, jkees, vol. 6, no. 4, pp.1-10, dec. 2006. 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[16] k. falconer, “fractal geometry; mathematical foundations and applications,” second edition, john wiley and sons ltd., 2003. [17] h. peitgen, h. jürgens, d. saupe, “chaos and fractals,” new frontiers of science, second edition, springer-verlag new york, 2004. [18] adnan görür, “description of coupling between degenerate modes of a dual-mode microstrip loop resonator using a novel perturbation arrangement and its dualmode bandpass filter applications,” ieee trans. microwave theory tech., vol. 52, no. 2, pp.671–677, feb. 2004. [19] smain amari, “comments on “description of coupling between degenerate modes of a dual-mode microstrip loop resonator using a novel perturbation arrangement and its dual-mode bandpass filter applications”,” ieee trans. microwave theory tech., vol. 52,no 9, pp.2190–2192, sept. 2004. [20] j. s. hong and m. j. lancaster, “microstrip bandpass filter using degenerate modes of a novel meander loop resonator,” ieee microwave and guided wave letters, 5, 11, nov.1995, 371–372. [21] j. s. hong and m. j. lancaster, “recent advances in microstrip filters for communications and other applications,” in iee colloquium on advances in passive microwave components, 22 may 1997, iee, london. jawad k. ali al-khwarizmi engineering journal, vol. 4, no. 3, pp 34-42 (2008) 42 تصمٍم مرشح امرار وطاقً ري شرٌحة دقٍقة متولذ مه الترتٍب الهىذسً الجزئً المبىً على اساس المروان الحلقً المربع ثىائً الىمط لمىظومات االتصاالت الالسلكٍة جواد كاظم علً انجايعح انتكُٕنٕجٍح/ قسى ُْذسح انكٓشتاء ٔاالنكتشٍَٔك الخالصة نتٕنٍذ سهسح تصايٍى يصغشج fractal geometryٌقذو فً ْزا انثحث تقٍُح تصًًٍٍح يثتكشج يثٍُح عهى اساط انتشتٍة انُٓذسً انجضئً اٌ انتقٍُح انتصًًٍٍح انًقتشحح يثٍُح . ري انششٌحح انذقٍقح تكٌٕ يُاسثح نتطثٍقاخ االتصاالخ انُقانح (bpf)انقٍاط نًششح االيشاس انُطاقً اٌ خاصٍتً ايالء انفضاء . minkowski-like prefractal geometryعهى اساط يشاتّ نتشتٍة يٍُكٌٕسكً انُٓذسً يا قثم انجضئً ٔانتًاثم انزاتً انهتٍٍ ًٌتهكًٓا ْزا انتشتٍة انُٓذسً تؤدٌاٌ انى انحصٕل عهى تشاكٍة صغٍشج انحجى ٔيتُاظشج ُْذسٍا فً يستٌٕاخ انتٕنٍذ اٌ تصايٍى يششحاخ االيشاس انُطاقً انًثٍُح عهى اساط ْزِ انتشاكٍة . انًختهفح، ٔتضداد ْزِ انتشاكٍة صغشا تاصدٌاد يستٌٕاخ انتٕنٍذ . انُٓذسٍح تكٌٕ يصغشج ٔتأتعاد تجعهٓا يُاسثح نالستخذاو فً اَظًح االتصاالخ انحذٌثح انتً تجشي انًحاكاج عهى ٔفق طشٌقح ie3d تى حساب اداء انًششحاخ انُاتجح عٍ انًستٌٍٕ االٔل ٔانثاًَ تاسخذاو انحقٍثح انثشيجٍح يقاسَح تأتعاد انًششح %64 ٔ %40، ٔقذ اظٓشخ انُتائج اٌ انًششحٍٍ انُاتجٍٍ نًٓا َسثتا تصغٍش قذسًْا تحذٔد(mom)اٌجاد انعضٔو . ، ششٌطح اٌ تكٌٕ انظشٔف انتصًًٍٍح َفسٓا فً كهتا انحانتsquare ring resonatorٍٍانتقهٍذي انًثًُ عهى اساط انًشَاٌ انحهقً انًشتع ٔغٍشْا يٍ دٔائش انًٕجاخ انذقٍقح )ٔعالٔج عهى رنك ، فاٌ انتقٍُح انتصًًٍٍح انًقتشحح راخ يشَٔح عانٍح حٍث آَا تٕفش نًصًًً انًششحاخ . حشٌح اكثش فً اختٍاس انًعانى انتصًًٍٍح، يقاسَح تًا تقذيّ انتصايٍى انًُشٕسج فً االدتٍاخ انُٓذسٍح نهًششح َفسّ (غٍش انفعانح monitoring and quality control of stud welding al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 5, no. 2, pp 32 43 (2009) simulation of free convection from an inclined heated thin plate in a square enclosure qahtan abdul zahra*, ahmed n. mehdy* and nora m. sahib** * department of mechanical engineering/ college of engineering/ university of kufa ** department of computer science/ educational college of girls/ university of kufa (received 25 november 2008; accepted 7 april 2009) abstract simulation of free convection heat transfer in a square enclosure induced by heated thin plate is represented numerically. all the enclosure walls have constant temperature lower than the plate’s temperature. the flow is assumed to be two-dimensional. the discretized equations were solved stream function, vorticity, and energy equations by finite difference method using explicit technique and successive overrelaxation method. the study was performed for different values of rayleigh number ranging from 103 to 105 for different angle position of heated thin plate(0°, 45°, 90°). air was chosen as a working fluid (pr = 0.71). aspect ratio of center of plate to the parallel left wall a2 take a constant and is equal to 0.5. the effect of the angle position of the heated thin plate on heat transfer and flow were addressed. with the increase of rayleigh number heat transfer rate increased in both vertical and horizontal position of the plate. for the vertical situation (γ=90°) of thin plate, heat transfer becomes more enhanced than for the horizontal situation (γ=0°) and the inclined situation (γ=45°) especially when the value of aspect ratio a1 is equal to 0.25. keywords: free convection, heat transfer, inclined heated thin plate, square enclosure. 1. introduction enhancement and depression of heat transfer through a differentially heated cavity are of significance for industrial applications such as solar collectors and nuclear reactors. considerable studies have been devoted to the problems of this aspect. many techniques of enhancing or depressing heat transfer have been experimentally and numerically investigated. one technique which has attracted significant research attention is to place a fin on the sidewall in order to enhance or depress heat transfer. ahmed and yovanovich [1] used numerical finite difference technique based on the marker and cell (mac) method to obtain solutions of a two-dimensional model of a square enclosure with laminar natural convection heat transfer from discrete heat sources. a discrete heat source is located in the center of one vertical side representing a highpower integrated circuit (ic). the conservation equations are solved using the primitive variables: velocity, pressure, and temperature. computations are carried out for pr = 0.72. bilgen and oztop [2] investigated a numerical study on inclined partially open square cavities, which are formed by adiabatic walls and a partial opening. the surface of the wall inside the cavity facing the partial opening is isothermal. steady-state heat transfer by laminar natural convection in a two dimensional partially open cavity is studied by numerically solving equations of mass, momentum and energy. streamlines and isotherms are produced; heat and mass transfer is calculated. rossano and saulo [3] investigated the heat transfer coefficient “h” of a isothermal vertical plate with h=0.15 m. the neighborhood surface influence in that coefficient is aimed at simulation and standard experimentation. a novel technology to measure the heat flux, called “tangential heat flux meter” is applied and simulation with a cfd commercial code was performed. five heat flux meters were glued on the vertical plate, heated 20°c over the air temperature. the neighborhood and air qahtan abdul zahra al-khwarizmi engineering journal, vol. 5, no. 2, pp 32 43 (2009) 33 temperature were maintained constant. the distance between the plate and the base wall (floor) was changed as well as the distance between the plate and the back side wall. simulation results will be compared with experimental. the result expected is an increasing of heat transfer coefficient, very useful in heat exchange devices. kandaswamy and others [4] studied the buoyancy induced flow and heat transfer inside a square cavity due to a heated thin plate placed vertically/horizontally. the flow motion in cavity depends on the heated plate itself. for an increase in grashof number, heat transfer increased in both the vertical and the horizontal situations. as the aspect ratio of heated thin plate is increased the heat transfer also increases. heat transfers become more enhanced in vertical situation than in horizontal situation. nithyadevi and. kandaswamy [5] made a numerical study on the effect of aspect ratio on the natural convection of a fluid contained in a rectangular cavity with partially thermally active side walls. the active part of the left side wall is the higher temperature than that of the right side wall. the top and bottom of the cavity and inactive part of the side walls are thermally insulated. nine different relative positions of the active zones are considered. the equations are discretized by the control volume method with a power law scheme and are solved numerically by the iterative method together with a successive over relaxation (sor) technique. the results are obtained for grashof numbers between 10 3 and 10 5 and the effects of the aspect ratio on the flow and temperature fields and the rate of heat transfer from the walls of the enclosure are presented. the heat transfer rate is high for the bottom–top thermally active location while the heat transfer rate is poor in the top–bottom thermally active location. the heat transfer rate is found to increase with an increase in the aspect ratio. xu and others [6] investigated direct numerical simulations of unsteady natural convection in a differentially heated cavity with a thin fin of different lengths on a sidewall at the raleigh number of 3.8 × 10 9 . it is found that the fin length significantly impacts the transient thermal flow around the fin and heat transfer through the finned sidewall in the early stage of the transient flow development. the results also indicate that the oscillations of the thermal flow around the fin in the quasi-steady stage are very sensitive to the length of the fin. avedissian and naylor [7] investigated a numerical study for the free convection in a tall vertical enclosure with an internal louvered metal blind, the study considers the effect of rayleigh number, enclosure aspect ratio, and blind geometry on the convective heat transfer. the numerical model has been validated against experimental measurements and the results have been presented in terms of an empirical correlation for the average nusselt number; the correlation is applicable to an internal metal blind. the nusselt number correlation can be combined with a simple one-dimensional model to closely predict the value of dimensionless velocity u. the aim of the present work is to study free convection in an enclosure with an inclined heated thin plate located at three situations(by changing angle position of the plate (0°, 45°, 90°) for different positions by changing the aspect ratio of plate position a1. 2. mathematical formulation and boundary conditions a schematic diagram of the two-dimensional square enclosure of length and height l filled with a fluid under investigation is shown in fig. 1. the top and bottom walls of the enclosure are adiabatic and the two vertical walls have constant temperature tc lower than plate’s temperature th. the cartesian coordinates (x, y) with the corresponding velocity components (u, v) are indicated in fig.1.a. the gravity g acts normal to the y-direction. in figure 1.b, h is the length of plate, h1 the distance of the center of plate to the perpendicular lower wall, and h2 is the distance of the center of plate to the parallel left wall. representing the position through cartesian coordinate system and assuming all other fluid properties to be constant, the flow of an incompressible boussinesq viscous fluid under the above specified geometrical and physical conditions is governed by the equations: ,0      y v x u …(1) , 1 2u x p y u v x u u            …(2) , 1 2 gv y p y v v x v u               …(3) ,2t y t v x t u        …(4) where   ctt    1 …(5) qahtan abdul zahra al-khwarizmi engineering journal, vol. 5, no. 2, pp 32 43 (2009) 34 the appropriate boundary conditions are:  u=v=0, t=tc at the lower and upper walls and  u=v=0, t=th for thin hated plate. introducing the following non-dimensional variables    , 2l    , l u u   , l v v   , l x x  , l y y  , ch c tt tt    , with th > tc, we get the vorticity-stream function formulation of the above problems (2)-(3) as 2 …(6) x prpr yxxy 2                ra … (7)   2 yxxy           … (8) we can obtain the horizontal and vertical velocities (u and v) from y u    , x v    …(9) with y u x v       …(10) the boundary conditions in the dimensionless  ψ= θ =0 at the all walls and thin plat  ζ=0 and θ=1 at the thin plat and at all walls, we can get the value of vorticity by using 2 2 n   …(11) where n is the normal direction on the wall. fig.1. geometric of present work and boundary conditions the non-dimensional parameters that appear in the equations are ra, the rayleigh number, pr, the prandtl number, g, the acceleration due to gravity, υ, the kinematic viscosity, α, the thermal diffusivity, β coefficient of thermal expansion, and θ dimensionless temperature. the local nusselt number is defined by nux tc tc g u v x y 0   y t 0   y t  th l l  h2 h1 h (a) (b) qahtan abdul zahra al-khwarizmi engineering journal, vol. 5, no. 2, pp 32 43 (2009) 35  ch plate x ttk lq nu   , lplate=h=a*l …(12) where q is the total heat transfer from thin heated plate downtupt qqq  …(13)    ch downtupt x ttk qq nu    *5.0 …(14)   downxupxx nununu  *5.0 …(15)  for the horizontal position     platethin upx y nu  …(16)     platethin downx y nu  …(17) dxnunu h xav  …(18)  for the inclined position the heat transfer from nodes source (on the heated thin plate) is shown in fig.(2) yxupt qqq  and yxdownt qqq  by using equation of nusselt number                         platethininclined upx yx nu  1 …(19)                         platethininclined downx yx nu  1 …(20)  dxnununu h downupav   *5.0 …(21)  for the vertical position platethin leftxrightx x nunu     …(22)  leftyrightyy nununu  *5.0 …(23) dynunu h yav  …(24) fig.2. heat transfer from inclined thin plate inclined heated thin plate yq xq x y xq yq downtq uptq source node neighboring node qahtan abdul zahra al-khwarizmi engineering journal, vol. 5, no. 2, pp 32 43 (2009) 36 3. method of solution a finite difference method based on successive over relaxation iterative method is used to solve numerically the non-dimensional governing equations (6)–(8). a computational program was written in fortran-90 language to compute the values of the required variables. the region of interest was covered with vertical and horizontal uniformly spaced grid lines equal to n. the vorticity and temperature distributions are obtained from eqs. (7) and (8), respectively. the stream function distribution was obtained from eq. (6) using successive over relaxation (sor) and a known vorticity distribution. an iterative process is employed to find the stream function, vorticity and temperature fields. the process is repeated until the following convergence criterion is satisfied 5 , ,, 10  ji jiji new oldnew   …(25) the numerical solutions are found for different grid systems from 100 x 100 to 120 x 120. 4. results and discussion free convection of low prandtl number fluid (0.71) corresponding to air is investigated numerically in the presence of a heated thin plate. the computations are carried out for a wide range of rayleigh number ra varying from 10 3 to 10 5 . the study was conducted for three different positions of the thin heated plate (by change a1) located at horizontal (γ=0°), vertical (γ=90°) and inclined (γ=45°) positions for all the cases which studied the value of aspect ratio a2 (aspect ration of the center of plate to the parallel left wall) equal to 0.5. the results are depicted as streamlines and isotherms plots. hence the problem is symmetrical about the center of the enclosure for the horizontal and vertical positions. we have plotted both isotherms and streamlines in to study the effect of the different locations of the plate. the rate of heat transfer across the enclosure is calculated in terms of the local and average nusselt number. 4.1. thin plate located horizontally when the heated thin plate is located horizontally the results are obtained by changing the rayleigh numbers and aspect ratio of the position of the plate (a1). fig.3. effect of rayleigh number on the stream lines and temp. distrib. for horiz. location (a=0.5, a1=0.5) 0.25 0.5 0.75 1 x 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 y 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.25 0.5 0.75 1 x 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 y 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.25 0.5 0.75 1 x 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 y 0.9 0.85 0.8 0.75 0.7 0.6 0.5 0.4 0.3 0.2 0.1 d) ra=10 3 e) ra=10 4 f) ra=10 5 0.25 0.5 0.75 1 x 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 y 0.2 0.16 0.12 0.08 0.04 0 -0.04 -0.08 -0.12 -0.16 -0.2 0.25 0.5 0.75 1 x 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 y 2.4 2.2 2 1.8 1.6 1.4 1.2 1 0.8 0.6 0.4 0 -0.4 -0.6 -0.8 -1 -1.2 -1.4 -1.6 -1.8 -2 -2.2 -2.4 0.25 0.5 0.75 1 x 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 y 10 9 8 7 6 5 4 3 2 1 0 -1 -2 -3 -4 -5 -6 -7 -8 -9 -10 a) ra=10 3 b) ra=10 4 c) ra=10 5 qahtan abdul zahra al-khwarizmi engineering journal, vol. 5, no. 2, pp 32 43 (2009) 37 fig.3. shows the streamlines and isotherms for a=0.5 and the plate is located at the center (a1=0.5), for different values of rayleigh numbers. it is observed that four cell centers are formed in the enclosure when rayleigh number is small. fluid motion is symmetric in the enclosure due to dominance of conduction mechanism. as rayleigh number increases convection becomes stronger and rotation over the plate becomes stronger in comparison to the one below the plate. in addition, as the space between the heated vertical boundary and plate is small, the rotation of fluid downward is prevented. the fluid flow below the plate produces stagnation point depending on the increase of rayleigh number. when looking at temperature distribution, it is observed that the temperature gradient becomes steeper and bigger at the top side of vertical boundaries depending on rayleigh number. as cooling process is symmetric, flow and temperature disturbances show asymmetric behavior according to x-axis. fig.4. shows the effect of aspect ratio of the location of the thin plate on the streamline and temperature distributions for a=0.5, and ra=10 5 , for a1=0.25; the resulting flow pattern is found to be bi-cellular and the corresponding isotherms show a weak convection type. as the plate is closer to the bottom wall the fluid under the plate is heated moderately and temperature gradient is steeper along the vertical side walls. when the position is changed (a1=0.5), the flow pattern remains the same, but corresponding isotherms show that convection becomes strong and when (a1=0.75), the convection becomes very strong. the heat transfer is increased to decrease the aspect ratio of plate and the convection mechanism is very effective. as can be seen, when the heated thin plate is on the upper of enclosure, the fluid under the thin plate is not affected considerably and recirculation is restricted to the upper corner. another expected result is that if the hot plate is on the upper wall of the enclosure there is no motion under the enclosure at a very low small motion relatively small motion, compared to the motion over the plate. fig.4. effect of aspect ratio on the stream lines and temperature distribution for horiz. location (ra=10 5 , a=0.5). 0.25 0.5 0.75 1 x 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 y 0.9 0.8 0.7 0.65 0.6 0.5 0.4 0.3 0.2 0.1 0.25 0.5 0.75 1 x 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 y 0.95 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.25 0.5 0.75 1 x 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 y 0.9 0.85 0.8 0.75 0.7 0.6 0.5 0.4 0.3 0.2 0.1 d) a1=0.25 e) a1=0.5 f) a1=0.75 0.25 0.5 0.75 1 x 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 y 15 13 11 9 7 5 3 1 0 -1 -3 -5 -7 -9 -11 -13 -15 0.25 0.5 0.75 1 x 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 y 4.5 4 3.5 3 2.5 2 1.5 1 0 -1 -1.5 -2 -2.5 -3 -3.5 -4 -4.5 0.25 0.5 0.75 1 x 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 y 10 9 8 7 6 5 4 3 2 1 0 -1 -2 -3 -4 -5 -6 -7 -8 -9 -10 a) a1=0.25 b) a1=0.5 c) a1=0.75 qahtan abdul zahra al-khwarizmi engineering journal, vol. 5, no. 2, pp 32 43 (2009) 38 4.2. thin plate located inclined (γ=45°) in this case calculations were performed to see the effect of rayleigh number in an enclosure with an inclined heated thin plate (γ=45°) built in for different aspect ratio of location thin plate. figure(5) shows stream lines and temperature distributions for a=0.5, a1=0.5 and rayleigh number change from 10 3 to 10 5 . as rayleigh number is small conduction, mechanism is dominant. as it is seen when rayleigh number is small, the distribution of stream lines up and below the thin plate will be approximately symmetric as shown in figure (5.a). as increase in rayleigh number shows non symmetrical behavior, it is note the maximum value of stream lines is up of thin plate because the thin plate will not obstruct the flow above the plate but will obstruct the flow lower the plate, also we note that the weak convection will decrease with increasing the angle of position. figure (5.d, e & f) shows the isotherms, as rayleigh number increased the change of temperature distribution above the inclined plate increases more than the change of below the plate because of the high convective flow above the plate. fig.5 effect of rayleigh number on the stream lines and temp. distrib. for inclined location (a=0.5, a1=0.5) figure (6) represents the effect of aspect ratio of the location of the thin plate on the stream lines and temperature distributions; we note that as the inclined thin plate is close to the lower wall(a1=0.25) the value of stream lines will be higher because the space between the heated vertical boundary and the inclined thin plate is large and the value of stream lines will be lower when the inclined thin plate close to the upper wall (a1=0.75). figure (6.d, e & f) shows temperature distribution; we note that at the lower aspect ratio (a1=0.25), the change in temperature distribution will be higher and that the hot fluid will penetrate more through the enclosure, as the plate is closer to the bottom wall, the fluid under the plate is heated moderately and the temperature gradient is steeper along the vertical side walls. as aspect ratio increases the temperature gradient and the hot fluid will penetrate less through the enclosure and the weak convection will be higher. 4.3. thin plate located vertically in this case, calculations were performed to see the effect of rayleigh number in an enclosure with a vertically heated thin plate built in for different of aspect ratio of location of thin plate. 0.25 0.5 0.75 1 x 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 y 0.4 0.36 0.32 0.28 0.24 0.2 0.16 0.12 0.08 0.04 0 -0.04 -0.08 -0.12 -0.16 -0.2 -0.24 -0.28 -0.32 -0.36 -0.4 0.25 0.5 0.75 1 x 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 y 3.75 3.5 3.25 3 2.75 2.5 2.25 2 1.75 1.5 1.25 1 0.75 0.5 0.25 0 -0.25 -0.5 -0.75 -1 -1.25 -1.5 -1.75 -2 -2.25 -2.5 -2.75 0.25 0.5 0.75 1 x 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 y 11 9 7 5 3 1 0 -1 -3 -4 -5 -6 -7 -8 -9 0.25 0.5 0.75 1 x 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 y 1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.25 0.5 0.75 1 x 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 y 1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.25 0.5 0.75 1 x 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 y 1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 d) ra=10 3 e) ra=10 4 f) ra=10 5 a) ra=10 3 b) ra=10 4 c) ra=10 5 qahtan abdul zahra al-khwarizmi engineering journal, vol. 5, no. 2, pp 32 43 (2009) 39 fig.6. effect of aspect ratio on the stream lines and temp. distrib. for inclined location (ra=10 5 , a=0.5) fig.7. effect of ra number on the stream lines and temp. distrib. for vertical location (a=0.5, a1=0.5) 0.25 0.5 0.75 1 x 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 y 6 5 4 3 2 1 0 -1 -2 -3 -4 -5 -6 0.25 0.5 0.75 1 x 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 y 17 15 13 11 9 7 5 3 0 -3 -5 -7 -9 -11 0.25 0.5 0.75 1 x 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 y 11 9 7 5 3 1 0 -1 -3 -4 -5 -6 -7 -8 -9 0.25 0.5 0.75 1 x 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 y 0.95 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.25 0.5 0.75 1 x 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 y 0.9 0.8 0.7 0.65 0.6 0.5 0.4 0.3 0.2 0.1 0.25 0.5 0.75 1 x 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 y 1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 d) a1=0.25 e) a1=0.5 f) a1=0.75 a) a1=0.25 b) a1=0.5 c) a1=0.75 0.25 0.5 0.75 1 x 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 y 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.25 0.5 0.75 1 x 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 y 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.25 0.5 0.75 1 x 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 y 0.9 0.85 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.25 0.5 0.75 1 x 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 y 10.8 10 8 6 4 2 0 -2 -4 -6 -8 -10 -10.8 0.25 0.5 0.75 1 x 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 y 4 3.5 3 2.5 2 1.5 1 0 -1 -1.5 -2 -2.5 -3 -3.5 -4 0.25 0.5 0.75 1 x 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 y 0.55 0.5 0.4 0.3 0.2 0.1 0 -0.1 -0.2 -0.3 -0.4 -0.5 -0.55 d) ra=10 3 e) ra=10 4 f) ra=10 5 a) ra=10 3 b) ra=10 4 c) ra=10 5 qahtan abdul zahra al-khwarizmi engineering journal, vol. 5, no. 2, pp 32 43 (2009) 40 fig.(7) shows stream lines and temperature distributions for a=0.5, a1=0.5 ra=10 3 -10 5 . symmetrical flow behavior is observed as expected. as rayleigh number is small conduction mechanism is dominant. as it is seen in figure (7.a-f), stream lines and temperature distributions also show symmetrical behavior and the temperature gradient has steeper gradient along the vertical side walls and the heated thin plate. as rayleigh numbers are increased, the recirculations intensify around the center of recirculation zone, especially on the upper part of enclosure. in the core region the fluids stay motionless. looking at the temperature distribution in figure (7.d, e& f), it can be seen that depending on the increase of the rayleigh number, temperature gradient increases and stratification is formed due to convection mechanism is effective on heat transfer. in figure(8), which stream lines and temperature distributions are given for a=0.5, ra=10 5 , a1=0.25,0.5,0.75 it can be seen that when increasing aspect ratio the value of the stream lines decreases because the space between the heated vertical boundary and the plate is small. in addition to that, the temperature distribution in the cold region will increase as shown in figure (8.d). therefore the maximum value of stream line when the plate is in the vertical location (γ=90°, a=0.5, a1=0.25) is equal to 14.589. fig.8. effect of aspect ratio on the stream lines and temp. distrib. for vertical location (ra=10 5 , a=0.5) 4.4. local and overall heat transfer local heat transfer is shown in terms of local nusselt numbers for three cases at the heated thin plate as mentioned before. in figure (9), local nusselt numbers were plotted at different aspect ratio of location of thin plate for three cases. we note in the horizontal situation, as shown in figure (9 a), the local nusselt is maximum at the edges of the heated thin plate and decreases to the lower value at the center of plate. figure (9.b) shows the local nusselt number for the inclined situation, we note the value of nusselt number is maximum at the left edge because the maximum gradient of temperature is at the left edge, while in the vertical situation, as shown in figure(9.c), we note that the local nusselt number is maximum at the lower edge(for a1=0.5, 0.75) because the maximum gradient of temperature is at the lower edge. also we note, for all cases, that with the 0.25 0.5 0.75 1 x 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 y 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.25 0.5 0.75 1 x 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 y 14 12 10 8 6 4 2 0 -2 -4 -6 -8 -10 -12 -14 0.25 0.5 0.75 1 x 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 y 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.25 0.5 0.75 1 x 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 y 6.8 6 5 4 3 2 1 0 -1 -2 -3 -4 -5 -6 -6.8 0.25 0.5 0.75 1 x 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 y 0.9 0.85 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.25 0.5 0.75 1 x 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 y 10.8 10 8 6 4 2 0 -2 -4 -6 -8 -10 -10.8 d) a1=0.25 e) a1=0.5 f) a1=0.75 a) a1=0.25 b) a1=0.5 c) a1=0.75 qahtan abdul zahra al-khwarizmi engineering journal, vol. 5, no. 2, pp 32 43 (2009) 41 decrease of the aspect ratio of location of the thin plate, the local of nusselt number will increase. generally, we note that the optimum situation for the studied cases is the vertical situation with a1=0.25; also we note that the inclined situation for the thin plate is better than the horizontal situation as shown in table(1). in the table (2) a comparison of average nusselt number between present work and kandaswamy [4] for the vertical situation and for the right side of the thin heated plate (a=0.5, a1=0.5, a2=0.5, ra=10 5 , pr=0.71), shows an approximation agreement between the two results. fig.9. effect of aspect ratio on the local nusselt number for the studied cases (ra=10 5 , a=0.5) . a) γ =0°, b) γ =45°, c) γ =90° table 1 the values of nuav for the studied cases at ra=10 5 nu av a1 γ 3.8985 0.25 0° 4.685 0.25 45° 5.1305 0.25 90° 3.8135 0.5 0° 4.4025 0.5 45° 4.816 0.5 90° 2.778 0.75 0° 3.225 0.75 45° 3.597 0.75 90° table 2 comparison the values of nuav from the vertical thin plate between present work and kandaswamy [4], (a=0.5, a1=0.5) ra=10 5 ra=10 4 ra=10 3 5.175 2.548 1.52 kandaswamy[4] 4.816 2.45 1.48 present work 5. conclusions a numerical calculation is performed for laminar free convection heat transfer in square enclosure with an inclined heated thin plate located in three situations horizontal (γ=0°), inclined (γ=45°) and vertical (γ=90°). the plate itself behaves like an obstruction and affects the flow field considerably. with the increase of rayleigh number local nusselt number increased in all situations. the value of the average nusselt number for inclined situation will be grater than the average nusselt number for horizontal situation and lower than average nusselt number for the vertical situation. as aspect ratio of location of the thin plate is decreases average nusselt number, namely, heat transfer increases. nomenclature a aspect ratio of the heated plate(=h/l). ai position of heated plates (=hi /l). g acceleration due to gravity(m/ s 2 ). hi the distance of the center of plate to the lower or left wall (m). l length and height of the enclosure (m). nu local nusselt number. a b c 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 x 0 2 4 6 8 10 12 14 16 n u ar=0.25 ar=0.5 ar=0.75 x 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 x 0 5 10 15 20 25 30 35 40 n u ar=0.25 ar=0.5 ar=0.75 x 0 2 4 6 8 10 12 14 16 18 20 22 nu 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 y ar=0.25 ar=0.5 ar=0.75 y qahtan abdul zahra al-khwarizmi engineering journal, vol. 5, no. 2, pp 32 43 (2009) 42 p pressure (pa). q total heat source (w). q components of heat source (w). ra rayleigh number. t dimensional temperature (k). u, v dimensional velocity components (m/s). u, v dimensionless velocity components. x, y dimensional coordinates(m). x, y dimensionless coordinates. greek symbols α thermal diffusivity (m 2 /s). β volumetric co-efficient of thermal expansion (1/k ). ψ dimensionless stream function. ρ density (kg/m 3 ). ρo density at to (kg/m 3 ). υ kinematic viscosity (m 2 /s). ω dimensional vorticity (1/s). ψ dimensional stream function (m 2 /s). γ angle of location of thin plate. δ dimensionless vorticity. θ dimensionless temperature subscripts c cold h hot i = 1, 2 av average t total superscripts + upper thin plate lower thin plate 6. references [1] g. r. ahmed and m. m. yovanovich,“ numerical study of natural convection from discrete heat sources in a vertical square enclosure”, j. thermophysics , vol. 6, no. 1, jan.-march ,pp.121-127, 1992. [2] e. bilgen, h. oztop, “natural convection heat transfer in partially open inclined square cavities”, int.j.heat mass transfer, vol.48, pp.1470-1479, 2005. [3] c. rossano, g. saulo, “natural convection at isothermal vertical plate: neighborhood influence” 18th international congress of mechanical engineering november 6-11, 2005, [4] p. kandaswamy, j. lee, a.k. abdul hakeem “natural convection in a square cavity in the presence of heated plate ” ,nonlinear analysis: modeling and control, vol. 12, no. 2, pp.203–212, 2007. [5] n. nithyadevi, p. kandaswamy, j. lee , “natural convection in a rectangular cavity with partially active side walls ”, int.j.heat mass transfer, vol.50,pp. 4688–4697, 2007. [6] f. xu, j.c. patterson and c. lei, “transient natural convection in a differentially heated cavity with a thin fin of different lengths on a sidewall ”, pp. 402–405, 16th australasian fluid mechanics conference, crown plaza, gold coast, australia, 2-7 december 2007. [7] t. avedissian, d. naylor, “free convection heat transfer in an enclosure with an internal louvered blind”, int.j.heat and mass transfer, vol.51,pp. 283–293, 2008. [8] a.d.anderson, c.j.tannehill, and h.r.pletcher, "computational fluid mechanics and heat transfer” ,hemisphere, new york, 1984. [9] chuen-yen chow, “an introduction to computational fluid mechanics”, john wiley & sons.inc, new york, 1979. [10] roache, j., "computational fluid dynamics "hermosa, albuquerque, new mexico, 1972. [11] bejan, a., "convection heat transfer”.john wiley & son.inc, new york, 1984. 43 32، صفحت 2، العذد 5مجلت الخوارزمي الهىذسيت المجلذ قحطان عبذ السهرة (200 9) 43 محاكاة اوتقال الحرارة بالحمل الحر مه صفيحت مسخىت وحيفت مائلت داخل تجويف مربع **وورا محمذ صاحب *أحمذ وعمت مهذي* قحطان عبذالسهرة فليح جايعت انكىفت/ كهٍت انهُذست/ةقسى انهُذست انًٍكاٍَكً * جايعت انكىفت/ كهٍت انتزبٍت نهبُاث/قسى انحاسباث** الخالصت كم جذراٌ انتجىٌف يحفىظت عُذ . يحاكاة الَتقال انحزارة بانحًم انحز داخم تجىٌف يزبع يٍ صفٍحت يسخُت يائهت قذ تى دراستها عذدٌا انحم انعذدي نهًعادالث أَجش بىاسطت حم . انجزٌاٌ فزض عهى أَّ ثُائً انبعذ. درجاث حزارة ثابتت أقم بكثٍز يٍ درجت حزارة انصفٍحت انذراست . يعادالث كم يٍ دانت انجزٌاٌ وانذوايٍت وانطاقت بإستخذاو انفزوق انًحذدة وتقٍُت انطزٌقت انىاضحت يع إستخذاو طزٌقت فىق انتزاخً 10 يٍ )أَجشث نقٍى يختهفت يٍ رقى راٌهً 3 10إنى 5 انهىاء قذ تى . (γ =0°, 45°, 90°)وألوضاع يختهفت نًىقع انصفٍحت ونثالث سواٌا ( تأثٍز ساوٌت انىضع . 0.5انُسبت انباعٍت نًزكش انصفٍحت نهجذار انًىاسي األٌسز قذ أخذث بقًٍت ثابتت ويساوٌت . اختٍارِ كًائع عًم فً انذراست خالل انُتائج تى انتىصم إنى أَّ انىضع انعًىدي نهصفٍحت انًسخُت ٌكىٌ . نهصفٍحت انًسخُت عهى اَتقال انحزارة وانجزٌاٌ قذ تى دراستّ .0.25 يساوٌت إنى a1أفضم يٍ انىضع األفقً وانىضع انًائم وخاصت عُذيا تكىٌ انُسبت انباعٍت al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 3952 (2014) trajectory tracking control for a wheeled mobile robot using fractional order pi a d b controller mouwafak a. tawfik* emad n. abdulwahb** salah m. swadi *** *,**department of machines and equipment engineering / university of technology ***department of electrical engineering / university of mustansiriyah. *email: drmat19853@yahoo.com **email: emadnaabd@yahoo.com ***email: sallah.mahdi99@gmail.com (received 26 february 2014; accepted 22 june 2014) abstract nowadays, wheeled mobile robots (wmrs) have found many applications as industry, transportation, inspection, and other fields. therefore, the trajectory tracking control of the nonholonomic wheeled mobile robots have an important problem. this work focus on the application of model-based on fractional order pi a d b (fopid) controller for trajectory tracking problem. the control algorithm based on the errors in postures of mobile robot which feed to fopid controller to generate correction signals that transport to torque for each driven wheel, and by means of dynamics model of mobile robot these torques used to compute the linear and angular speed to reach the desired pose. in this work a dynamics model of mobile robot was driven for the case where the centroid of mobile robot platform is not coincide with reference frame of mobile robot (i.e. reference frame is located at midpoint of driven wheels axis), while the inertia is counted for. the evolutionary algorithm has been used to modified the parameters (kp, kd, ki,a, and b) of the fopid controller for wheeled mobile robot. simulation results show the effectiveness of the proposed control algorithm: that is demonstrated by applied this controller at four case studies (circular trajectory, s-shape trajectory, infinity trajectory, and line trajectory at two cases, with presences of disturbance and without), these results shows good matching between desired trajectory and simulation one while error in posture goes to zero rapidly. keywords: mobile robot, trajectory tracking, nonholonomic systems, fractional order pid controller. 1. introduction wheeled mobile robots are increasingly present in industrial and service robotics, particularly when flexible motion capabilities are required, on reasonably smooth grounds and surfaces. several mobility configurations (wheels number and type, their location and actuation, single or multi-body vehicle structure) can be found in the application . the most common for single-body robots are differential drive and synchro drive (both kinematically equivalent to a unicycle) the navigation problem may be divided into three basic problems [1]: tracking reference trajectory, following a path, and point stabilization. earlier literatures focus on kinematic model of mobile robot (e.g. steering system) of mobile robot, and perfect velocity is assumed to generate the actual vehicle control inputs [2], but there are three problems with this approach; 1the perfect velocity tracking assumption does not hold in practice. 2disturbances are ignored. 3complete knowledge of the dynamics is needed [3]. recently literatures focus on integration of the nonholonomic kinematic controller and the dynamics of the mobile robot. where a sliding mode control scheme is proposed to solve the trajectory tracking problem based on the exact mailto:drmat19853@yahoo.com mailto:emadnaabd@yahoo.com mailto:sallah.mahdi99@gmail.com mailto:sallah.mahdi99@gmail.com mouwafak a. tawfik al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 3952 (2014) 40 discrete time model of the robot [4]. a backstepping control approach tracking into account the specific vehicle dynamic to convert a steering system command into control inputs for the actual vehicle was implemented in [5]. fuzzy logic control (flc) is based on a back-stepping approach to asymptotic stabilization of the robots position and orientation around the desired trajectory proposed in [6]. the tracking control problem for a wheeled mobile robot, where the error in posture of mobile robot used as input control was the topic of this work. in this paper a simple and significant controller based on fopid for a two active wheel nonholonomic mobile robot subjected to pure rolling and no side slipping condition was proposed. the developed dynamic model includes inertia moment of driving wheels, the total mass and inertia moment which has a centroid offset from the connection center of wheeled mobile robot through the compute torque method, and a fopid controller are applied for stabilizing the robot around its reference trajectory even in presence of disturbance/noises and modeling uncertainties. 2. kinematic & dynamic modeling of nonholonomic wmr 2.1. kinematic of nonhlonomic mechanical system in mobile robotics the mechanical behavior of the robot must be understood, both in order to design suitable robots for task and to understand how to generate control software, for instance mobile robot hardware [7]. in general kinematics deals with study of motion without considering the force that affects it. in spite of the publish work considered a reference point of the plat for of mobile robot at c.g., it is more it is more confidence to attached platform frame at c as shown in figure 1 which is located in mid axis that connect driven wheels, (in other word the midpoint of the drive wheels axis c is considered as a reference point of plat form of mobile robot that will follows the desired trajectory and the inertia of the mobile robot is accounted for). the deferential drive robot platform as a rigid body on wheels, operating on a horizontal plane, is shown in figure 1. fig. 1. a nonholonomic mobile platform. from figure 1, kinematic equation of mobile robot in world frame {o,x,y} can be described as follows: … (1) …(2) …(3) the kinematic equation 1,2,and 3 can be represented as follows[8,9,10] : …(4) where: …(5) c.g yc c d x y yc xc xc 2r 2l mouwafak a. tawfik al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 3952 (2014) 41 …(6) the nonholonomic constraint states that the mobile robot can only move on the direction normal to the axis of the driving wheels, i.e, the mobile base satisfies the conditions of pure rolling and non slipping [11,12]. …(7) the constraint equation (7) can be written in matrix form: …(8) where …(9) from (4 and 7) it is found that s(q) is a full rank matrix (n-m) formed by a set of smooth and linearly independent vector fields spanning the null space of a(q), i.e. s t (q)a t (q) = 0. …(10) the mobile robot shown in figure 1 is a typical example of a nonhlonmonic mechanical system. it consists of a vehicle with two driving wheels mounted on the same axis, and a front free wheel. the motion and orientation are achieved by independent actuators, e.g., dc motors providing the necessary torques to the rear wheels. the position of the robot in an inertial cartesian frame {o,x,y} is completely specified by the vector q = [xc yc ] t where xc,yc are the coordinates of the center of mass of the vehicle, and is the orientation of the basis{ c , xc , yc } with respect to the inertial basis. 2.2. dynamics of nonholonomic mechanical system as represented by r. fierro, at el [5], many nonholonomic mechanical system can be describes by the following dynamic equations: …(11) where is a symmetric positive definite inertia matrix , is the centeriptal and corilis matrix, denotes the surface friction , is the gravitational vector , denotes bounded unknown disturbances including unstructured unmodeled dynamics, is the input transformation matrix, is the input vector, is the matrix associated with the constraints, and is the vector of constraint forces. the lagrange formalism is used to find the dynamic equations of wheeled mobile robot. assume the trajectory of the mobile robot is constrained on the horizontal plane and there is no friction, then g(q) = 0 and f( ) = 0 [13]. since the system cannot change its vertical position, its potential energy, u, remains constant. now from the system shown in figure 3, kinetic energy is equal to: …(12) the lagrange's formula is given by: …(13) …(14) …(15) …(16) …(17) …(18) …(19) …(20) …(21) neglecting the disturbance term in eq.(11), dynamical equation of motion for wheeled mobile robot in figure 1. can be expressed in matrix form as follows: ...(22) where : i = ic + md 2 mouwafak a. tawfik al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 3952 (2014) 42 to find lagrange multiplier newten-euler formula in lateral direction of mobile robot will be … (23) …(24) differentiating equation (7), (i.e. the constraint equation of nonholonomic wheeled mobile robot). …(25) substitution (24) in (23) yields: …(26) from the orthogonality properties of the nullspace matrix to the constraint matrix (s t (q)a t (q) = 0) helps to eliminate the lagrange multipliers. differentiating equation (4), substituting this result in equation (11), and then multiplying by (s t (q)), the complete equations of motion of the nonholonomic mobile platform are obtained as follows: …(4) …(27) . fig. 2. kinetic diagram of nonholonomic mobile robot. 3. control algorithm 3.1. computed torque (ct) controller in general, the trajectory tracking problem aims at tracking a reference mobile robot with known posture qr=[xr,yr, r] t . therefore the errors between the actual and desired postures are: …(28) equation (22) can be written as follows: … (29) the brunovsky canonical form can be developed by differentiating e(t) twice and writing it in terms of the state x [14]: …(30) from equations 28, 29, and 30 one can found: …(31) to develop the ct controller, a linear system design procedure will be used in order to select a feedback control u(t) that stabilizes the tracking error equation, then compute the torques for the motors are computed using eq.(31). a pid feedback for u(t) with a derivative gain matrix kv ,a proportional gain matrix kp ,and integral gain matrix ki produce pid ct controller where the motor torque is equal to: …(32) in pid controller case, three parameters kp, kd, and ki should be tuned to design the controller. one of the possibilities to improve pid controllers is to use fractional – order pi a d b c d x y yc xc ( ) p c.g ω mouwafak a. tawfik al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 3952 (2014) 43 controllers with real index of derivative and integral. 3.2. fractional order pi a d b controller equation of fractional order controller was described as [15]. …(33) where e(t) is the error between a measured process output variable and a desired set point, and u(t) is the control signal. equation (33) illustrates that the five control parameters (kp, ki, kd, a, and b) should be tuned to design an accurate controller. the integral order and derivative order add more flexibility to design an fopid controller. continuous transfer function in s domain of fopid controller is be given by [15]: …(34) the orders a and b can be any real numbers. from equation (3.4) the classical pid controller can be obtained by setting a=b=1. when a=1 (or 0) and b=0 (or 1) a normal pi (or pd) controller can be obtained. figure 3 shows that the fractional order pi a d b controller generalizes and expands the classical pid controller from a point to plane. fig. 3. generalized fopid controller 3.3. evolutionary algorithm the evolutionary algorithm (ea) is an optimization algorithm that is used to search for optimal solutions to a problem [16]. this algorithm operates on a population of potential solutions applying the principle of survival of the fittest to produce best approximations to a solution. evolutionary algorithms provide a universal optimization technique that mimics the type of genetic adaptation that occurs in natural evolution [16,17]. unlike specialized methods designed for particular types of optimization tasks, they require no particular knowledge about the problem structure other than the objective function itself. at each iteration step, a new set of approximations is assumed by the process of selecting individuals according to their level of fitness in the problem domain and breeding them together using operators, such as mutation, crossover and selection borrowed from natural genetics in order to generate the new generations [18]. it shares the same features with the genetic algorithm (ga) in terms of selection. 3.3.1. structure of evolutionary algorithm by using the evolutionary algorithm, the natural processes such as selection, crossover, mutation and reinsertion are modeled. figure 4 depicts the structure of a generic evolutionary algorithm[19]. a pd pi p 1 1 pid pi a d b b mouwafak a. tawfik al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 3952 (2014) 44 fig. 4. structure of an e.a. method. 3.4. implementation of the fopid controller with proposed system using matlab/simulink & optiy packages figure 5 shows the layout of the simulink model of fopid controller with controlled system. the evolutionary algorithm has been used to modify the parameters of the fopid controller for mobile robot the optiy program is used to obtain the optimal parameters of the fopid controller. from equation 36, five parameters kp, kd, ki, a and b. each individual vector has five parameters (five-dimension variables vector). for reducing the time of optimization, the ranges of fopid parameters are selected as: to evaluate the objective function, the following function will be used: start randomly generate initial population p (t=0) evaluate objective function select fitness parent crossover (offspring generation) mutation evaluation of offspring reinsertion t=t+1 are termination criteria met? select best individual end yes mouwafak a. tawfik al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 3952 (2014) 45 the initial values and optimal values of the fopid controller parameters are shown in table 1 figures 6 and 7 demonstrate the changing of the control parameters (values of kp , kd , ki , a and b) during the optimization steps. after 3957 optimization steps, the parameters of the fopid controller reach to steady state values (the optimal values) while the objective function jf value reach to small value as illustrated in figure 8. fig. 5. simulink model of fopid controller with proposed. table 1, initial and optimal value of fopid controller. parameter kp ki kd a b initial value 1 1 1 0.7 0.1 optimal value 5.7632 0.005596 3.296 0.893 0.394 q qd v qdot q 1 l x y theta thetaout fcn thetacorrection du/dt qdotdot2 du/dt qdot t1 q1 qdot1 v vdot mobile-robot1 qiv e(m*b) ive(stb) 1 vector concatenate1 vector concatenate step scope4 saturation q qdot out1 stv(q,qdot) qout1 stm qout1 s matrix multiply product3 matrix multiply product2 matrix multiply product1 pid pid controller3 pid pid controller2 pid pid controller1 1 s integrator1 1 s integrator mouwafak a. tawfik al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 3952 (2014) 46 fig. 6. optiy program results where: a) variation of kp, kd, and ki parameters during optimization process, b) variation of a1,and a2 parameters during optimization process, c) f1, f2, and f3 are objective functions, d) optiy program workflow window. 4. simulation result the trajectory tracking problem for nonholonomic vehicles is posed as follows. let there be prescribed a reference cart …(35) with for all t, find ct such that , where and are the reference velocity vector , and reference orientation respectively. the proposed controller is verified by means of computer simulation using matlab/simulink. the kinematic and dynamic model of the nonholonomic mobile robot described in section 2 is used. the simulation is carried out by tracking a desired position (x,y) and orientation angle with circular , s-shape, and lemniscates trajectories in the tracking control of the robot. the parameters values of the robot model are taken from [20,21], which are as follows: m=0.65 kg, i = 0.36 kg.cm 2 , l = 0.105 m, r =0.033 m, and tacking d = 0.01m for this mobile robot. the resulting mobile robot trajectory tracking, obtained by the proposed fopid controller is shown in figures 7 to 16 including trajectory tracking , tracking error, and linear and angular velocity of mobile robot, the sampling period was set to t0 = 0.1 s. in these cases, there are no external disturbances. (b) (a) (c) (d) mouwafak a. tawfik al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 3952 (2014) 47 1the circular trajectory was generated from the desired linear velocity and angular velocity . thus the desired circular trajectory, which has continuous gradient with rotation radius constant, can be describe as follows: …(36) …(37) …(38) the initial posture of the desired trajectory is , while the actual initial posture of the robot is , circular trajectory tracking simulation and posture error curves are shown in figures 7 to 8 respectively. it's very clear that good tracking performance that achieved by means of the proposed controller. fig. 7. circular trajectory tracking. fig. 8. trajectory tracking error. 2the s-shape trajectory compose of nine segments five of them are line segment has constant linear and angular velocity ω , while the arc segment has linear and angular velocity and ω . the initial posture of reference trajectory is set at while the actual initial posture of robot is . simulation results of both trajectory tracking and the posture error curves are shown in figures 9 and 10, although s-shape trajectory has sudden change in path, the proposed controller shows good trajectory tracking and the posture error goes to zero in short time. fig. 9. s-shape trajectory tracking. fig. 10. tracking error in s-shape trajectory tracking. mouwafak a. tawfik al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 3952 (2014) 48 3the lemniscates or infinity represent a most challenge in trajectory tracking cases, which has continuous gradient with rotation radius changes with constant linear velocity , this trajectory can be described by the following : …(39) …(40) … (41) the robot model starts from the initial posture as it's initial condition. trajectory tracking and tracking error are shown in figures 11 and 12, from these curves one can found very good trajectory tracking and posture error bounded by less than ±0.01 m for position error (i.e. ) and between ±0.02 rad for orientation error (i.e. ) that’s usually happened because of presence of tipping points in such trajectory and these values have a little effect on the trajectory tracking performance as that clear in figure 11. fig. 11. lemniscates trajectory tracking. fig. 12. tracking error in infinty trajectory tracking. 4simulation is also out for desired line trajectory; in this case a disturbance [7], is added to the robot system as unmodeled kinematics and dynamics disturbance in order to prove the adaptation and robustness ability of the proposed controller. the robot starts form the initial posture as its initial conditions, simulation result is figured out for both presences of disturbance and without it where figures (13 and 14) show the trajectory tracking and posture error respectively without presence of disturbance, while figures (15 and 16) show trajectory tracking and posture error respectively with presence of disturbance. simulation results confirm the power full of the proposed controller in rejected external disturbance and return to desired trajectory in short time furthermore very good trajectory tracking in both cases. fig. 13. line trajectory tracking. mouwafak a. tawfik al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 3952 (2014) 49 fig. 14. trajectory tracking error. fig. 15. line trajectory tracking with presence disturbance. fig. 16. trajectory tracking error with presence of disturbance. 5. conclusion evolutionary algorithm used as optimization method for tuning fopid controller, implemented throughout optiy software. the control algorithm has been applied for four kind of reference trajectory (i.e. circular, s-shape, infinity, and line) these trajectory performed by using simulation program (i.e. matlab/simulink) and result showed good agreement. simulation work demonstrates the effectiveness of the proposed algorithm with twowheeled mobile robot and proved that this method is characterized by its robustness with disturbance and uncertainties in the system model. acknowledgments the authors gratefully acknowledge dr. ahmed s. al-araji, control & system dept. university of technology and dr. ammar abdulshaheed aldair, electrical engineering dept. university of basra, for their helps during this work. list of symbols symbol definition integral order. derivative order. b(q) the input transformation matrix. reference point of mobile platform. c.g. center of gravity. offset of cintroid from axis of wheels. e(t) error between the actual and reference posture in time domain. surface friction vector. g(q) gravitational vector. kd derivative gain. ki integral gain. kp proportional gain. 2l the distance between the two wheels for mobile robot. m(q) inertia matrix of mobile robot. mass of mobile robot pose vector of mobile robot. time derivative of pose vector of mobile robot. qr reference trajectory vector. time second derivatives of reference trajectory vector. radius of the wheel for mobile robot. time domain. s(q) transfer matrix. s t transfer matrix transpose. u(t) control input in time domain. mouwafak a. tawfik al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 3952 (2014) 50 v velocity vector (linear and angular velocity). the centripetal and carioles matrix. xc and yc local frame of mobile robot. xc and yc pose of mobile robot in global coordinate frame. velocity of mobile robot in xdirection. velocity of mobile robot in ydirection. the robotic orientation angle. linear velocity of mobile velocity the vector of constrained force. angular velocity of mobile robot. input torque vector. bonded unknown disturbances vector. list of abbreviation abbreviation definition fopid fractional order of proportional, integral, and derivative controller. wmr wheeled mobile robot. 6. references [1] c. canudas de wit, h. khennouf, c. samson, and o. j. sordalen, "nonlinear control design for mobile robot," in recent trends in mobile robots, y. f. zheng, ed., world scientific, 1993, pp. 121156. [2] y. kanayama, y. kimura, f. miyazaki, and t. noguchi, "a stable tracking control method for an autonomous mobile robot," proc. ieee int. conf. rob. autom., 1990, pp. 384-389. [3] c. samson, "time-varying feedback control of a nongolonomic cart," in lecture notes in control and information science, c. canudas de wit, ed. , springerverlag, new york, 1991, pp. 125-151. [4] nino-suarez p. a., aranda-bricaire e., velasco-villa m. ,"discrete-time sliding mode trajectory tracking control for a wheeled mobile robotic," proceedings of the 45th ieee conference on decision and control, san diego, usa, december 13-15, 2006, pp. 3 025 – 3 057. [5] r. fierro, and f. l. lewis, "control of a nonholonomic mobile robot: backstepping kinematics into dynamics"journal of robotic systems 14(3), 149-163 (1997). [6] oscar castillo, luis t. aguilar, and selene cardenas, "fuzzy logic tracking control for unicycle mobile robots," engineering letters, 13:2, el_13_2_4 (advance online publication: 4 august 2006). [7] ahmed s. al-araji, et al, "applying posture identifier in designing an adaptive nonlinear predictive controller for nonholonomic mobile robot" elsevier, neurocomputing, 99, (2013), pp. 503-554. [8] h-x zhang, g-j dai and h zeng, "a trajectory tracking control method for nonholonomic mobile robot," proceedings of the international conference on wavelet analysis and pattern recognition beijing, china, 2-4 nov. 2007, pp. 7-11. [9] s. x. yang, h. yang, q. max and h. meng, "neural dynamics based full-state tracking control of a mobile robot," proceedings of the ieee international conference on robotics & automation, new orleans, la, 2004, pp. 4614-4619. [10] a.m. bloch, "nonholonomic mechanics and control," new york: springer-verlag, 2003. [11] y. yamamoto and x. yun, "coordinating locomotion and manipulation of a mobile manipulator," in recent trends in mobile robots, y. f. zheng, ed., world scientific, 1993, pp. 157-181. [12] k. hornik, m. stinchcombe, and h. white, ‘‘multilayer feedforward networks are universal approximators,’’ neural networks, 2, 359–366, 1989. [13] tiemin hu, and simon x. yang, "real-time motion control of a nonholonomic mobile robot with unknown dynamics" nserc of canada under grant rgpin-227684. to s. x. yang [14] lewis, f. l., jagannathan, s., and yesildirek, a., "neural network control of robot manipulators and nonlinear system," pp. 147-167, taylor and francis ltd, t. j. international ltd, padstow, uk, 1999. [15] xue, d., et al. "linear feedback control analysis and design with matlab", usa: the soceity for industrial and applied mathematics. 2007. [16] back, t. "evolutionary algorithms in theory and practice", oxford university press, london, uk, 1996. mouwafak a. tawfik al-khwarizmi engineering journal, vol. 10, no. 3, p.p. 3952 (2014) 51 [17] goldberg, d. e. "genetic algorithms in search, optimization and machine learning", reading, ma: addisonwesley,1989. [18] sumathi, et al., "evolutionary intelligence an introduction to theory and applications with matlab", spring verlag berlin heidelberg, german, 2008. [19] ammar a. aldair, "neurofuzzy controller based full vehicle nonlinear active suspension system" ph.d. thesis, university of sussex brighton uk, march 2012. [20] k. h. su, y. y. chen, s. f. su, "design of neural – fuzzy – based controller for two autononmously driven wheeled robot" neuroconputing 73(2101)2478-2488. [21] internet website < http://www.parallax.com>, robotics with the boe-bot text manual v3.0, (accessed october 2011). http://www.parallax.com/ (2014) 3952، صفحة 3، العدد10دجلة الخوارزمي الهندسية المجلموفق علي توفيق م 52 pidالجزئي نوع المسيطر باستخدامالمتحركة بعجالت للروبوتات األثرسيطرة تتبع ***صالح مهدي سوادي** عماد ناطق عبد الوهاب *موفق علي توفيق الجامعة التكنولوجية/ قسم هندسة المكائن والمعدات**،* الجامعة المستنصرية/ كلية الهندسة/ قسم الهندسة الكهربائية*** drmat19853@yahoo.com :البريد االلكتروني* emadnaabd@yahoo.com :البريد االلكتروني** sallah.mahdi99@gmail.com :البريد االلكتروني*** الخالصة في مجال الصناعة، النقل، والتفتيش وغيرها من المجاالت االخرى في الوقت الحاضر العديد من التطبيقات( wmrs) عجالت ب المتحركةلروبوتات ل نموذج مستند االبحث يركز على على تطبيق هذا. المهمة تعد من المشكالتأيجاد منظومة سيطرة لهذا النوع من الروبوتات لتقوم بتتبُع أثر معين وبالتالي فإن المسيطر الىالروبوت المتحرك موضع خطاء في ال على تغذية اعتمدت خوارزمية التحكم. ع االثرمشكلة تتبُ لحل pid على المسيطر الجزئي نوع (fopid) نموذج الخطية والسرعة الزاوية من خالل حل االتم حساب السرعة ، القيادةعجالت لعزم دوران تحول الى لتوليد إشارات التصحيح التي للحالة التي اليتطابق فيها تحركبوت المونموذج الديناميكي للراال اشتق. الوضع المطلوبللوصول الى الرياضي للحركة الديناميكية للروبوت المتحرك ، كما تم االخذ بنظر االعتبار تأثير قوى القصور الذاتي منتصف محور عجالت القيادة في اختيرتلمنصة الروبوت والتي االطار المرجعي مركز الثقل مع للروبوت fopid المسيطر الجزئي ( kp, ki, kd, a, and b) برامتراتلتعديل خوارزمية التطوريال تاستخدام .للروبوت على االطار المرجعي ،مسار دائري) انواع من المسارات ةأربع على المسيطرهذه الذي تبين من تطبيق و المقترح مسيطرالنتائج المحاكاة فعالية أظهرت .المتحرك بعجالت أن ولتتبع االثر المطلوب مطابقة جيدة النتائج كما بينت، ( هو بدون خارجي ضطرابأوجود بحالتين المسار المستقيم ول، مسار إنفينيتي ، و sشكل مسار .إلى الصفر بسرعةذهب ضع تخطأ في الموال دالة mailto:drmat19853@yahoo.com mailto:emadnaabd@yahoo.com mailto:sallah.mahdi99@gmail.com abstract al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 4, no. 4, pp 71-81 (2008) thermo elasto-plastic analysis of rotating axisymmetrical bodies using modified von-mises yield criterion imad a. hussain*, hameed d. lafta** and rafa'a d. hussain*** *college of engineering/ university of al-nahreen **college of engineering/ university of kufa ***college of engineering/ university of al-muthana (received 25 march 2008; accepted 24 october 2008) abstract in the present work, the behavior of thick-walled cylinder of elasto-plastic material (polymeric material) has been studied analytically. the study is based on modified von-mises yield criterion (for non metallic material). the equations of stress distribution are obtained for the cylinder under general cases of elastic expansion, plastic initiation and elastic-plastic expansion. a computer program is developed for evaluating the stress distribution. the solution is carried out for worst boundary conditions when the cylinder is subjected to the combination of pressure load, inertia load, and temperature gradient. the results are presented graphically in terms of dimensionless stresses and radius ratio. they indicate that the thermal and rotational loads are greatly influencing the stress distribution and the initiation of plastic zone, as well as the spreading out of the plastic zone. moreover, it was found that the critical values of loads required for starting plastic deformation are determined by the amount of the applied load and the type of loading conditions, and it is found that the variation of stresses are greatly influenced by increasing of the temperature gradient at constant pressure and inertial loads than other increases in loading conditions. keywords : thick wall cylinder, elastic-plastic, axisymmetrical bodies. 1. introduction there are many practical engineering problems, which may related to the determination and predicting of stress state in elastic-plastic problem of thick-walled cylinder that will cause a particular material to fail under a particular set of loading conditions, presents a major problem to the engineer. the phenomenon of the elastic-plastic is appeared because of the structural material exhibited to load exceeding the required critical load to produce initial yielding condition in the material. this phenomenon plays an important role in diverse applications including pressure vessels, flywheels, driving shafts, shafts in turbines and generators, and solid propellant grain. the problems of elastic-plastic for thickwalled cylinders have been solved by most investigators based cylinders subjected to mechanical loadings such as internal and external pressures with either thermal loading or angular velocity. bland [1], obtained the solutions of the elastic and plastic stresses and strains and the displacements by using tresca's yield criterion and its associated flow rule, when a thick-walled tube of linear work-hardening material is subjected to internal and external pressures and its surfaces are maintained at different temperature gradients. he found the equivalent plastic strain, which depends on the yield stress for a workhardening material and determined the stresses and residual stresses for non-work-hardening material. derrington [2], derived the principal stresses in a long elastic cylinder subjected to pressure and temperature and calculated the greatest shear stress under combined loading. also he calculated the largest pressure before first yield occurs at the inner radius by using tresca's yield criterion. he presented with graphs the effects of load imad a. hussain al-khwarizmi engineering journal, vol.4, no.4, pp 71-81 (2008) 72 combinations, thickness ratios, and end conditions. mahdavian [3], developed the stress equations for a closed end, long, thick walled cylinder subjected to a logarithmic temperature gradient under an internal pressure and an external tensional moment. the solution of the derived equations is based on the shear strain energy yield criterion. the results indicated that the temperature effect plays an important role in the initiation of yielding. johnson and mellor [4], and chakrabarty [5], have been treated the theoretical solution of the elastic and elastic-plastic behavior of thick-walled cylinders and the rotating disks made of an isotropic non hardening material. they assumed that the mechanical and physical constants are all unaffected by the variation in the temperature. the solution of their equations is based on tresca's yield criterion. hearn [6], has been studied theoretically the solution of thick-walled cylinders and rotating disks. he found the distribution of elastic and elastic-plastic stresses by using tresca's yield criterion. in the following cases. hassan et al. [7] presented the theoretical solution for the elasto-plastic problem of solid propellant grain under the internal pressure, heat gradient during burning and linear acceleration of the rocket during flying course for the case of plane strain. they were also studied the thermal effect due to temperature gradient, and the effect of axial acceleration and failure due to yielding of material. arnold et al. [8] studied the problem of a rotating disk of a single or a number of concentric disks forming a unit. an analytical model capable of performing an elastic stress analysis for single/multiple, annular/solid, isotropic disk systems subjected to both pressure surface tractions and body forces (in the form of temperature-changes and rotation fields) is derived. he discussed the influence of applying pressure, the temperature gradient, and rotating conditions. meijeren [9] studied the deformation and failure of glassy polymers. the study is based on a compressible leonov model which provides an adequate description for the rate and temperature depended yield, strain softening, and strain hardening. it is concluded that an increase in network density of the polymer results in a proportional increase in strain hardening modulus. many analytical or numerical investigations studied the problem of elastic-plastic for thickwalled cylinder was made of metallic material where it is subjected either to internal pressure only, temperature gradient only, angular velocity only or any combinations of these loads. most of the pervious researches are using tresca's yield criterion and little are using the modified vonmises yield criterion. the elastic-plastic problem of thick-walled cylinders that made of a polymeric material had received a little attention in spite of its importance and variety of its applications. thus in the present study an attempt was made to put into perspective the problem of the elastic-plastic state of rotating cylinder made of polymeric material. the analysis adopted in the present work is based on the modified von-mises yield criterion which takes into account the behavior of polymeric materials. 2. mathematical modeling: the stress analysis of thick-walled cylinder under the internal pressure or/and external pressure, uniform temperature gradient, and angular velocity can be considered as plane-strain elasto-plastic problems. the formulation of elasto-plastic relation for a complex problem under multi axial stresses can be achieved by assuming a reasonable mathematical model to correlate between the uni-axial test results and the multi-axial case. the elastic-plastic behavior, for a real multi axial state of stress can be transformed from that of uni-axial state of stress by defining the following parameters [9]. ithe elastic stress-strain relations. iian initial yield condition, specifying the state of stress for which plastic flow first sets in. iiia flow rule which relates the plastic strain increments to the stresses and stress increments. ivhardening rule for establishing the condition for subsequent yield form a plastic state. 2.1. modified von-mises criterion: the assumption of von-mises yield criterion quite reasonable for ductile materials [10], but it is of unacceptable assumption for polymers. for this reason a modified von-mises criteria was proposed to account for the differences in tensile and compressive yield stresses, and the influence of the mean stress or the "hydrostatic component" of the applied stress on the yield surface. imad a. hussain al-khwarizmi engineering journal, vol.4, no.4, pp 71-81 (2008) 73 z r r r r       rrr  .2 fig. 2. thick-walled cylinder (a) (b) z r   r r r b a   the modified von-mises yield criterion can be deduced [11] by inserting the unequal yt and yc into von-mises yield criterion thus:       )1...(2 332211 2 13 2 32 2 21 yyccc ct   (1) where c11, c22 and c33 are constant in the principle directions and are added to keep eq. (1) in balance. to evaluate these constants consecutively, uniaxial tension is assumed, where 1= x and 2 = 3 = 0 then the eq. (1) becomes: cyy xxct 11 222   where   2 11 2 xct yyc  at yielding y tx  then  yyyc tct  2 11 or  yyc tc   111 2 similarly  yyc tc   222 2 and  yyc tc   333 2 substituting c11, c22 and c33 into eq. (1), then:          )2...( 22 321 2 13 2 32 2 21 yyyy cttc     2.2. thermo elastic-plastic solution of thick-walled cylinder: the basic assumptions introduced for the analysis are as follows: [7] the thick-walled cylinder is a polymeric material and the yielding behavior is covered by modified von-mises yield criterion. the stressstrain curve in simple tension can be assumed elastic perfectly plastic (fig (1)). 1. the plane strain condition is prevailed i.e. εz =0. 2. the temperature is taken to be symmetrical about the axis of symmetry independent of the axial coordinate z. 3. material is homogeneous and isotropic. 4. material properties such as yield surface, modulus of elasticity and poisson's ratio are assumed to be temperature-independent for suitable temperature range [7]. fig.(2) shows a thick-walled cylinder subjected to pressure load, thermal gradient and rotating about longitudinal axis, with inner radius (a), and outer radius (b). the stress distribution through the wall cylinder are given by (see appendix a):         (3.a)... 81 23 12121 22 22 21                r v v trdr rv e r c v c v e r r a              (3.b)... 81 21 112121 22 22 21                  r v v trdr rv e v te r c v c v e r a     where c1 and c2 are constants of integration. these constants can be determined by the boundary conditions according to the type of loading conditions. in the present work, the cylinder is assumed to be subjected to general loading conditions represented by pressure load (internal pressure or/and external pressure), steady state temperature gradient and inertia load (angular velocity), thus the boundary conditions are given by : σy ε σ fig.1. behavior of elasticperfectly plastic material. imad a. hussain al-khwarizmi engineering journal, vol.4, no.4, pp 71-81 (2008) 74 r = -pi , t = ti at r = a r = -po , t = to at r = b …(4) 2.3. elastic expansion: the elastic solution of general loading condition can be deduced by substituting the boundary conditions of eq. (4) into eqs. (3) then:     (5.a)... lnln 1 1 11 2 2 2 2 2 22 222 2 2                                     r br b t r r ba bar r b a p pir         ).5...( 1lnln 1 1 23 21 11 2 2 2 2 2 22 222 2 2 b r b v v r b t r r ba bar r b a p pi                                             where a, b : inner and outer radii. pi, po : internal and external pressures. ti, to : inner and outer temperature. p pp a i oi ia b      , 1 , 2 81 23 2  v v r p      oip ttt v te t     , ln12   2.4. yield initiation and first plastic zone formation: when the pressure, temperature difference and angular velocity are sufficiently high, yielding will occur at the radius where the induced stresses are satisfying the modified von-mises yield criterion; i.e.: [7]            2 12 2 222 yy yy tr zrrtrzzr   where yr : yield ratio and is given by ( yr =yc / yt) the general equation for thick-walled cylinder under general loading conditions is given by: (see appendix a ) :              02 12 2 434241 2 333231 2 232221 2 131211 yy ctcrcayy ctcrca ctcrcactcrca tr ppirt ppi ppippi it is clear that, in the case of general loading conditions there are three cases depending on which loading is firstly initiates yielding. thus the stresses distributions in this case are similar to that given in eq.(5) with taken into consideration that the terms corresponding to each type of loads are given in terms of its critical values that first causing yield initiation. it is worthily mentioning that the yielding is beginning at the inner radius (a) in all cases. 2.5 elastic-plastic expansion: when the applied load exceeds the critical load (required to causes the initial yielding) a plastic zone spreads from the inner radius to the outer radius. the radius of the elastic-plastic boundary at any stage may be named "c", as shown in fig (3). where c is represents the radius of intersection between the elastic and plastic zones. * plastic zone ( a ≤ r ≤ c ): analytical solution (exact solution) can not be derived to evaluate the stresses distribution in the plastic region (i.e. at (a ≤ r ≤ c)) in the above mentioned cases. this attributed to the fact that the modified von-mises yield criterion added a a elastic zone plastic zone fig.3. elastic plastic zones of thickwalled cylinder. c b imad a. hussain al-khwarizmi engineering journal, vol.4, no.4, pp 71-81 (2008) 75 term that take into consideration the yielding for polymeric material. whereas, this term resulting in a complex form for the yielding criterion. thus, to evaluate the stresses distribution an alternative approach using numerical method is adopted. whereas, the radial stress component in the plastic zone can be evaluated from the equilibrium equation, by means of runge-kutta method, which is given by : )8...(0 2 crar rdr rrd       while, the hoop stress component can be obtained for corresponding value of radial stress, by using newton-raphson algorithm on the bases of the modified von-mises yield criterion which defined by :          ...(9) 2 12 2 2 22 yy yy tr zrrtrz zr        ** elastic zone ( c ≤ r ≤ b ): the stress distribution in this case can be obtained by determining the constants of eq. (5) in terms of the radius (c) which is satisfying the elastic-plastic interfacing. thus eq. (5) are given by :     (10.a)...lnln 1 1 11 2 2 2 2 2 22 222 2 2                                      brc r b c c p pccccr r b t r r bc bcr r b a                                                b r b v v c c p pcccc r b t r r bc bcr r b a 1lnln 1 1 23 21 11 2 2 2 2 2 22 222 2 2      where: 12   c c c p a , c b c  , p p c o c  81 23 2  v v r p      oip ttt v te t     , ln12   3. results & discussion: a numerical technique was used to solve the derived equations of stress distribution throughout the cylinder wall. a cylinder made of polyvinylchloride (p.v.c.) of inner radius (a) of 100 mm and outer radius (b) of 200 mm (i.e.a/b=0.5), that assumes elastic-perfectly plastic behavior, was used as a polymeric material. the properties of the material are shown below in table (1). the properties of the material were assumed to be independent of the temperature for appropriate temperature range [7]. table 1 properties of p.v.c. material material properties value young's modulus (gpa) 3 yield stress (mpa) 55 coefficient of linear thermal expansion (k-1) 60x10-6 specific gravity 1.4 poisson's ratio 0.4 material density (kg/mm3) 1400x10-9 yield ratio (yr) 1.5 the numerical solution is achieved by developing of a computer program based on a runge-kutta method and netwon-raphson algorithm. in the present study, a cylinder of inner radius of (100 mm) and outer radius of (200mm) subjected to general loading condition (pressure load, inertia load , and temperature gradient) was investigated. the results of program runs are shown graphically in figs.(4), (5), and (6) respectively, which show the variation of stress ratio with radius ratio for rotational speed, temperature gradient, and pressure loads. the results reflect the effect of the rotational speed, temperature gradient, and pressure load on the variation of the radial and hoop stresses throughout the cylinder wall respectively. the results in fig.(4) and (5) of the stress variation indicate that the values of stresses in the elastic case are greater than those values of the plastic initiation and elastic-plastic cases. this attributed to the fact that when the elastic limit is exceeded, the plastic flow is occurred and law deformation forces are experienced which reflects the assumed elastic – perfectly plastic behavior of the cylinder material. imad a. hussain al-khwarizmi engineering journal, vol.4, no.4, pp 71-81 (2008) 76 -1.2 -1.0 -0.8 -0.6 -0.4 -0.2 0.0 1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2 sr / y t radius ratio (r/a) elastic plastic initiation elasticplastic pi = 20 m pa pr = 0.25 δt = 273 k yr = 1.5  < cr  cr  > cr -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2 sq / y t radius ratio (r/a) elastic plastic initiati on pi = 20 m pa pr = 0.25 δt = 273 k yr = 1.5  <cr  cr  >cr fig.4. variation of stresses with respect to the radius ratio for cylinder subjected to variable inertia load (angular speed), constant pressure and thermal loads. -0.5 -0.5 -0.4 -0.4 -0.3 -0.3 -0.2 -0.2 -0.1 -0.1 0.0 1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2 radius ratio (r/a) elastic plastic initiation elastic-plastic -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0 1 1.11.21.31.41.51.61.71.81.9 2 sq / y t radius ratio (r/a) elastic plastic initiation elasticplastic pi = 20 m pa pr = 0.25 δt < δtcr δt = tcr δt> δtcr fig.5. variation of stresses with respect to the radius ratio for cylinder subjected to variable thermal load, constant pressure and inertia loads. (a) (b) (a) (b) sr / y t imad a. hussain al-khwarizmi engineering journal, vol.4, no.4, pp 71-81 (2008) 77 -0.5 -0.4 -0.3 -0.2 -0.1 0.0 1 1.11.21.31.41.51.61.71.81.9 2 sr / y t radius ratio (r /a) elastic plastic initiation elasticplastic pi = 20 m pa pr = 0.25 = 20 rad / sec yr = 1.5 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1 1.11.21.31.41.51.61.71.81.9 2 sq / y t radius ratio (r /a) elastic plastic initiation pi = 20 m pa , pr = 0.25  = 20 rad / sec fig.6. variation of stresses with respect to the radius ratio for cylinder subjected to variable pressure load, constant inertia and thermal loads. while, the results in fig.(6) shows different behavior because the pressure is clearly a compressive load. finally, the results show that, the increase of the temperature gradient influences the stress distribution with presence of inertial and pressure loads more than other cases for the same values of inertial and pressure loads. this attributed to the fact that the inertial load results in additional deformation load in form of centrifugal of thick wall cylinder subjected to general loading conditions has been investigated. forces. 4. conclusions: the elasto-plastic behavior it has been clarified that the type and amount of loads are greatly influence the stress distribution, the plastic initiation as well as the spreading out of the plastic zone throughout the cylinder wall. the inertial load results in producing an additional deformation force in form of centrifugal force which in leads to the fact that the increase in temperature gradient in the presence of the inertia and pressure loads is greatly affecting the stress distribution than other cases. also, it is concluded that when the elastic limit of the material is exceeded, a plastic flow is occurred and law deformation forces is required, which reflects the elastic-perfectly plastic assumed behavior of the cylinder material. 5. notation: a, b inner and outer radii of cylinder c radius of elastic-plastic interface r variable radius e modulus of elasticity g modulus of rigidity pi , po internal and external pressures respectively. pr pressure ratio (pi /po) ti , to inner and outer temperatures respectively u displacement us shear strain energy yt , yc tensile and compressive yield stresses respectively. (a) (b) imad a. hussain al-khwarizmi engineering journal, vol.4, no.4, pp 71-81 (2008) 78 6. greek letters: x , y , z stress components in x, y and z axes 1 , 2 , 3 principal stresses r ,  , z radial, hoop, and axial stresses respectively. x , y , z strain components in x, y and z axes. r , , z radial, hoop, and axial strains respectively.  density of material  poisson's ratio  angular velocity  coefficient of thermal expansion  outer pressure to inner pressure ratio 7. appendix (a): 7.1. general solution: referring to fig. (2) which shows a thickwalled cylinder subjected to pressure load, thermal gradient and rotating about longitudinal axis, with inner radius (a), and outer radius (b). by considering the equilibrium of forces acting on the element, at radius (r), in the radial direction then:    (a.1) 2 sin2 22   r rrrr r rrr        for  is small then: 22 sin   if r→0 then r→0, therefore, the above equation simplifies to (a.2) 0 2    r rdr rrd    where r : radial stress : hoop stress  : material density : angular velocity the elastic stress-strain relationships at a point in the cylinder wall are given by [3].   teve zrr      teve zr      teve rzz    …(a.3) where e : modulus of elasticity r, , and z,: radial, hoop and axial strains respectively. z: longitudinal stress  : poisson's ratio  : thermal coefficient of expansion t: temperature equation [4],              a b r b tt ln ln where δt : temperature gradient the plane strain condition can be assumed, z = 0, and the above equations can be reduced to:   )4...(  tev rz   the strain-displacement relations [4]:   r u dr du r    where u is the displacement along the radial direction. substituting eqs (a.4) and (a.5) into eq (a.3), then:    (a.6.a) 1 1    tevv e v dr du rr      (a.6.b) 1 1    tevv e v r u r   substituting eqs. (a.6.a) and (a.6.b) into eq. (a.2) and integrating with respect to r then, the general stress equations are given by: (2008 )81-71، صفحة 4، العذد 4 مجلة الخىارزمي الهنذسية المجلذ عماد احمذ حسيه 79         )7...( 81 23 12121 22 22 21 aar rr cc v v trdr v e vv e r a r                                 )7...( 81 21 1 12121 22 2 2 21 ba v v trdr v e v te vv e r r r cc r a                                 (a.7.c) 211211 22 1        rc v v v te vv ve z   7.2. derivation of the general equation of yield initiation: the boundary conditions when thick-walled cylinder is subjected to internal pressure or/and external pressure, steady state temperature gradient are:  r = -pi , t= ti at r = a  r = -po , t= to at r = b the elastic solution of general loading condition can be deduced by substituting the boundary conditions for each case into eqs. (3.10) then:     )1...( lnln 1 1 11 2 2 2 2 2 22 222 2 2 ab r br b t r r ba bar r b a p pir                                              b)1...(b 1lnln 1 1 23 21 11 2 2 2 2 2 22 222 2 2                                        r b v v r b t r r ba bar r b a p pi        )1...( ln 1 2 ln2 23 2 21 2 2 222 2 cb v r b v v v t r barva p piz                          where p p i o , a bp a i i      , 1 2 81 23 2  v v rp      , ln12   v te t p    tt oi t  when the pressure, temperature difference and angular velocity are sufficiently high, yielding will occur at the radius where the induced stresses are satisfying the modified von-mises yield criterion; i.e.:          )2...(212 2 222   byyyy trzrrt rzzr     where y y y t c r  from eqs. (b.1) it is found that:       )3...( 1312112 2 2 2 2 22 2 2 1ln 1 2 23 21 212                                               bctcrca r b t r r ba r r b a ppip pir v v                  )4...( 232221 2 2 2 2 2 22 22 2 2 2 ln1 ln 1 12 23 21 21 2111                                                 bctcrca r b t r r ba ba r r b a ppip piz r b v v v v v v      imad a. hussain al-khwarizmi engineering journal, vol.4, no.4, pp 71-81 (2008) 80             (b.5) ln ln 1 21 23 21 3 21 211 1 333231 2 2 2 2 22 2 22 2 2 2                                                         ctcrca r b t r ba r ba rr b a ppip pirz r b v v v v v v                   (b.6) ln 1 12 ln41 23 212112 434241 2 2 22 2                                         ctcrcat r ba ra ppip pizr v r b v v vv      the general equation for thick-walled cylinder when it is subjected to internal pressure and/or external pressure, temperature gradient and angular velocity can be found by substituting eqs (b.3), (b.4), (b.5) and (b.6) into eq (b.2), thus:          )7....( 02 12 2 434241 2 333231 2 232221 2 131211 byy ctcrcayy ctcrca ctcrca ctcrca tr ppirt ppi ppi ppi      where the constants are given by:       v v v r b c r b c r r ba c r b c 2111,1ln 1 2 23 21 2,12 2 2 2 212 2 2 13 2 2 22 122 2 11                              v v v v r b v v v v v rba r ba c r b c r b c r r ba bac 23 21 321 ,2111 ln1ln 1 12 23 21 21 222 2 22 32 2 2 2 31 2 2 2 23 2 2 22 22 22                             ln 1 12 ln41 23 2 12 112 lnln 1 21 243 2 22 42 2 41 2 2 2 33                   v r b v v v v r b v v c rbac c r b c 8. references: [1] bland, d. r., "elasto-plastic thick-walled tubes of work-hardening material subject to internal and external pressure and to temperature gradients", j. mech. phys. solids, vol. 4, pp. 209-229, 1956. [2] derrington, m. g., "the onset of yield in a thick cylinder subjected to uniform internal or external pressure and steady heat flow", int. j. mech. sci., vol. 4, pp. 83-103, 1962. [3] mahdavian, s. m., "yielding condition of a closed end, pressurized, thick-walled cylinder subjected to a torsional moment and temperature gradients", int. j. pres. ves. & piping, vol. 9, no. 5, pp. 339-353, 1981. [4] johnson, w. and mellor, p. b., "engineering plasticity", van nostrand reinhold company london, 1980. [5] chakrabarty, j., "theory of plasticity", mcgraw-hill book company, 1987. [6] hearn, e. j., "mechanics of materials", 2nd edition, vol. 2 , 1985. [7] hassan, a., imad, a. h. and mohammed, a. n., "thermo elasto-plastic analysis of solid propellant rocket grain with internally burning", the college of engineering of kufa university, 2000. [8] arnold, s. m., saleep, a. f. and al-zoubi, n. r., "deformation and life analysis of composite flywheel disk and multi-disk systems", naca tm-2001-210578. [9] daived, r “yield and plastic flow” massachusetts institute of technology, cambridge, ma02139, vol. 15, 2001 [10] meijeren, h. e. “deformation and failure of polymer glasses” harold geert hendrik van melick, 2002 [11] michael, f. a. and david r. j., "engineering materials", international series on materials science and technology, vol.34, 1982. (2008 )81-71، صفحة 4، العذد 4 مجلة الخىارزمي الهنذسية المجلذ عماد احمذ حسيه 81 باستخذام معيارية اللذن لألجسام المذورة المتناظرةالتحليل الحراري المرن ميسيس المطىرة فىن *** رافع داخل حسيه ** حميذ دويج لفته *عماد احمذ حسيه جامعت انىهزَه/كهُت انهىذست * جامعت انكىفت/كهُت انهىذست** جامعت انمزىً/كهُت انهىذست *** الخالصة إشارث انىخائج انً ان حانت األحمال انحزارَت و انخذوَزَت نها حأرُز . و وصف انقطز انالبعذٌ ةعزضج انىخائج بذالنت االجهاداث انالبعذٌ وكذنك و جذ ان انقُم انحزجت نألحمال . كبُز عهً طبُعت حىسَع االجهاداث و عهً حذود انخشىَه انهذن وسزعت اوخشار مىطقت انخشىَه انهذن وقذ بُىج انىخائج ان انخغُُز انحاصم فٍ حىسَع االجهاداث , انمسهطت و انخٍ حسبب انخشىَه انهذن حخأرز بقُمت وطبُعت انخحمُم عهً االسطىاوت .انشَادة فٍ حاالث انخحمُم االخزي َخارز بصىرة كبُزة فٍ حال سَادة االحمال انحزارَت وربىث االحمال انخذوَزَت وانضغظ اكزز مه بىُج انذراست . انهذن نالسطىاواث انسمُكت و انمصىىعت مه انمىاد انبىنُمزَت بصىرة وظزَت–حمج دراست انخصزف انمزن , فٍ هذا انبحذ وجذث انمعادالث انخاصت بخىسَع االجهاداث ححج أقسً ظزوف األحمال .مُسُش انمطىرة نهمىاد غُز انمعذوُت باالعخماد عهً معُارَت فىن وجذث معادالث حىسَع االجهاداث نالسطىاوت ححج حاالث انخمذد . انهذوت, انهذوت-انمزوت, انمسهطت عهً االسطىاوت ونحاالث انخشىَه انمزوت . انهذنانمزن وانىشىء انهذن و انخمذد انمزن نهظزوف انحذَت انحزجت و انىاحجت مه األحمال انمشخزكت مه حم اَجاد حىسَع االجهاداث ببىاء بزامج حاسىبُت مطىرة ووجذث انحهىل . ضغظ و درجت حزارة وأحمال حذوَزَت microsoft word ???? ?? ????1122 this is an open access article under the cc by license : al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 17, no. 4, december, (2021) p. p. 1222 analysis of magnetorheological normally close directional control valve hadeer ali kamal* maher yahya salloom** *,**department of mechatronics engineering / al.khawarizmi college of engineering / university of baghdad *email: hadeer.a.aljuboury@gmail.com **email: drmahir@kecbu.uobaghdad.edu.iq (received 8 august 2021; accepted 19 december 2021) https://doi.org/10.22153/kej.2021.12.005 abstract this valve is intended for use in valves for steering movement, using the qualities of the magneto-rheological (mr) fluid to regulate the fluid, direct contact without the utilization of moving parts like a spool, a connection between electric flux, and fluid power was made, the simulation was done to employ the" finite element method of magnetism (femm)" to arrive at the best design. this software is used for magnetic resonance valve finite element analysis. the valve's best performance was obtained by using a closed directional control valve in the normal state normally closed (nc) mr valve, with simulation results revealing the optimum magnetic flux density in the absence of a current and the shedding condition, as well as the optimum pressure. finally, the mr valve proved successful in proportionally dominant in the direction and the quickness of the hydraulic actuators, and the new model allows hydraulic valves to be replaced with smaller valves while also lowering complexity. (some of the figures in this article are only available in color in the online edition.) keywords: magneto-rheological (mr) fluid, mr valve, femm magnetic programming, normally close (nc)mr valve. 1. introduction the directional control valve is the most important components of the hydraulic system. the directional control valve has a sophisticated design, with a moving spool controlling the actuator's direction for the desired speed. one of the controlled fluids is a magneto-rheological (mr) fluid. without the usage of moving parts, direct contact between the fluid power and magnetic field can be established using the properties of mr fluid. shaju et al. [1] have constructed a “wheatstone bridge hydraulic power circuit” using four mr valves to operate a hydraulic actuator using a gear pump as the source of hydraulic power. the output load and driving current to the mr valve determined the hydraulic system's performance. an mr directional control valve with no moving parts was recently built using the rheological properties of mr fluid. salloom and samad came up with the new compact design. they recommended integrating a series of singular mr valves into a small unit that makes the design and manufacturing process easier. they demonstrated how the mr directional control valve is built and how it works. as a result, the primary goal of this work is to provide the results of an experimental test of a newly built mr directional control valve [2]. at 0.6 a of current, an annular resistance slot of 1 mm in width, and a radial resistance slot of 0.5 in width, an optimal magnetic field distribution, and a higher pressure fall of 24.5 bars were achieved. theoretical calculations, analysis, simulation, and hadeer ali kamal al-khwarizmi engineering journal, vol. 17, no. 4, p.p. 1222 (2021)   13 experimental tests were used to calculate valve performance, particularly pressure drop. at 1.2 a of current, the pilot pressure fall can reach. 26.5 bars, which is consistent with simulation results. femm software is being used by other researchers for analysis [3]. salloom and samad [4] described the construction and present the individual directional control (3/4 mr valve), in which finite element analysis with femm software was used to achieve the optimal design, and this design achieved good results for the intensity of magnetic flux in the effective gap, and then an inverse relationship between the current and the flow of intelligent liquid. the design was distinguished by the valve's tiny size and length. if enough of the coil outside the functional area if is damaged, it can be easily and quickly replaced. for hydraulic actuator control, the “(4/3 mr valve)” can replace various types of spool directional control valves. three variants of the magnetic resonance mr damper valve structure were created, built, and tested as part of this research. the volume of the mr damper, the volume of the mr fluid, and the number of coil turns were measured. these variables were compared, and it was discovered that the proposed mr damper with the concentric valve structure has a higher dynamic range of damping force with a less massive and lower price in terms of easy assembly, direct maintenance, and mr fluid volume (where the serpentine settled valve on the bypass channel of the damper ). neglected to focus on the variation of the damping force, as it was proven that this force can be increased from 20 n to 600 n at a current of 0.3a, the simulation results were completely consistent with the experimental results when the friction force and the accumulating force were neglecting neglected to focus on the variation of the damping force, as it was demonstrated that this force can rise from 20 n to 600 n at a current of 0.3a [5]. the terms “magnetic resonance fluid” (mr fluid) and “magnetic resonance elastomer” (mr elastomer) have steadily gained popularity. mr fluid is a type of characteristic fluid that is transient when the magnetic field intensity changes. when there is no external magnetic field, the magnetic particles are uniformly dispersed in the base fluid, and the mr fluid is in a fluid state; the ferromagnetic particles form a chain structure parallel to the magnetic field line when an external magnetic field is applied, and the magnetic fluid changes from a liquid to a semisolid in microseconds [6]. the radial mr valve with a single-coil was simulated using ansys software, which works on a decrease in pressure by changing the internal structure (increase in dimensions to easily block the internal channel), where the response time with the current was tested as well as the change in pressure under variable loads. the overall pressure loss of the primary valve is 1.842 mpa when the applied current is 1.8 a, whereas the total pressure drop of the optimum valve is 2.58 mpa, indicating a 40.07 percent increase. meanwhile, at a current of 1.25 a, the greatest damping force of the better cylinder system controlled by the radial mr valve can reach around 3.6 kn [7]. the objectives of this research are to create and refine an "mr directional valve" that is adequate for use in hydraulic monitoring systems that use the mr fluid. as a result, the fundamental goal of this paper is to suggest a squeezed design of mr valves for use in directional control valves that use mr fluid. this valve's structural design and operating principles are explained, along with a functional experiment. "a simulation using the finite element method of magnetism (femm) is also used to analyze the valve's fulfillment". 2. construction of a normally close mr valve for controlling the direction of movement of the mr, a normally close (nc) valve was created to be small and simple to install. a body, double covers, and four singular mr valves make up this valve. the valve's body was prepared to hold four singular valves. the active portion is a single mr valve (element). the last includes a pulley, double cores, two magnets, and a return route through which the magnetic flux can pass, as indicated in figure 1. low carbon steel was selected for the steel rail because of its low relative permeability (1018), the coils are straightforward to change because they are placed outgoing of the active area. the coil's parties are simply fed via the body's opening. the single mr valve has a short length (19 mm). it can be utilized in mr valves with 4/3 directional control, making it smaller than the exemplary one. hadeer ali kamal al-khwarizmi engineering journal, vol. 17, no. 4, p.p. 1222 (2021)   14 (a) schematic of the single coil mr valve. (b) mr valve (element) construction fig. 1. assembly of singular mr valve (element). the valve body's magnets are one of the most powerful sorts of magnets, they are made of neodymium (n35). the inner contents are surrounded by a low carbon steel cylinder with a 0.5 mm gap. the valve body is sealed on both ends with teflon insulating material, with a hole on each end for the smart mr fluid to enter and depart. the dimensions of this valve are shown in figure 2. (a) 3d of mr valve hadeer ali kamal al-khwarizmi engineering journal, vol. 17, no. 4, p.p. 1222 (2021)   15 (b): 2d of mr valve fig. 2. the dimension (in mm) of the mr valve. 3. the precept of work the presence of a magnetic field due to the presence of permanent magnets in the valve body, the iron particles in the mr fluid line up in the form of chains, forming a solid substance that prevents the fluid from passing through, the valve is completely closed in its normal state, preventing the fluid from passing through without shedding any current. when an electric field is activated dc on the valve coil, an electric field opposite the magnetic field is generated, cancelling the magnetic field's effect on the valve. this causes the solid chains to disintegrate with the liquid, allowing the liquid to pass through and the valve to become completely open. an increase or decrease in the current is provided to the coil to adjust the amount of fluid flow through the current. depending on which position of the valve is chosen, this can be accomplished utilizing various coil connections with certain electrical circuits. the circuit's purpose is to supply variable current to the valve's coils while also selecting the valve's operation position. the circuit is provided with a 12 v dc input and produces a variable current of 0–2.5 a as an output. a variable current is achieved by connecting a rheostat to the valve's coil in series, and the selected position is achieved by connecting a three-position select switch to relays. 4. modeling the following methodology was used to evaluate the nc mr valve's functionality. “based on the mr fluid flow and rheological stress, the pressure mode was employed as a playback mode in a singular mr valve, as shown schematically in figure3. fig. 3. representation of the pressure mode of the nc mr fluid flow. hadeer ali kamal al-khwarizmi engineering journal, vol. 17, no. 4, p.p. 1222 (2021)   16 the mr fluid's yield shear stress reduced as the magnetic field increased, and vice versa." the mr fluid behaved like newtonian fluids in the existence of a magnetic field". as a result, the mr fluid follows the bingham plastic’s flow in the existence of a magnetic field, with variable yield strength. bingham's equation in this scenario is as follows (jolly et al., 1998): 𝜏 𝜂𝛾 𝜏 𝐻 𝜏 𝜏 … 1 where τ is shear stress, η is the dynamic viscosity, γ ̇ is the fluid shear rate, 𝛕 𝐲is magneticfield-dependent shear yield stress, and h is the magnetic field (h=0). this equation was utilized to create a gadget that could work with mr fluid. the pressure decrease in valve mode is caused by the sum of the viscous (pure rheological) component and the magnetic-field-dependent (mr) components the value of this pressure drop is calculated using the following approximation: (li and colleagues, 2003): ∆𝑃 2 6𝜂𝑄𝐿 𝑔 𝑤 𝑐𝜏 𝐿 𝑔 … 2 the viscous component of this equation, whereas the dynamic viscosity is η (pa s), the flow rate is q (m3/s), and the geometric length, width, and gap size of the flow rectangle channel are l, w, and g (m), respectively. theoretically, this component of the equation is correct. the other half of the equation, on the other hand, is reliant on the magnetic field ingredient. in reaction to the applied magnetic field, the yield shear stress τ (n/mm ) is promoted. in the rheological pressure drop, the geometric values l and g in the unit (m) are the same. many considerations were crucial during the design period of single mr valves. the fluid gap, the number of wire turns, the bobbin diameter, the flux length, the core, and the flux return thickness, were all considered. other factors may influence the pressure drop, and the empirical factor ‘c’ represents the influence of these other factors. to build an efficient mr valve, the flux density in the fluid gap should be constant. the relative permeability of the mr fluid is significantly lower than that of low-carbon steel (such as two cores, bobbin, and flux return). in this investigation, the distance is reduced to 0.5 mm. 5. analysis except for yield shear stress τ , all resolve elements on the right-hand side are known, according to equation 2. an analysis is required to deem the pressure drop of a singular mr valve. the yield shear stress( τ )of mr fluid in valve gaps is studied using the magnetic flux density acquired from the analysis. equation 2 can be used to compute the pressure drops. in the magnetic analysis, the cylindrical shape of the mr valve has a complex structure. only femm can be used for the analysis. it is insufficient to evaluate the mr valve as a 2-d axisymmetric pattern due to symmetry as illustrated in figure 4. the magnetic circuit was modeled using a finite element method, as illustrated in the diagram. figure 5 shows the model created with the femm software. fig. 4. the dimensions of mr valve in femm software fig. 5. femm model of nc mr valve hadeer ali kamal al-khwarizmi engineering journal, vol. 17, no. 4, p.p. 1222 (2021)   17 figure 6 depicts the magnetic field direction in the mr valve. the mr fluid ownership was chosen by the mrf-132dg standard [8]. from the magnetic flux density (b) vs. magnetic field strength (h) (bh) curve of the mr fluid, point h and b belong to the mr fluid as data for novel nonlinear material introduced to the fem analysis. the magnetic coils had a total of 400 turns. during the simulation, a current of 0 to 2.5 a was delivered to the coil. to model an mr valve, mr fluid was used. nguyen et al. (2007, 2008) have approximated a polynomial equation to obtain the shear stress. 𝜏 𝑘𝑃𝑎 52.962𝐵 176.51𝐵 158.79𝐵 13.708𝐵 0.1442 … 3 [9] b is magnetic flux density in tesla calculated along the valve gap by finite element analysis by femm software. fig. 6. the nc mr valve magnetic field direction. 6. results and discussion the femm software was used to perform a finite element study on the nc mr valve. the mr valve's performance is restricted by the mr fluid's finite yield stress. a magnetic strength of 340–390 kamp/m is ideal. the shear stress in the yield zone is about 47 kpa. figures 7 and 8 illustrate the magnetic density and magnetic field results of the mr valve’s resolve test using the femm software, respectively. when there is no current (i=0a), the findings are expressed in the nomenclature of magnetic strength in the valve's active gap. the “magnetic strength intensity(h)” was found to be 300 kamp/m according to the proposed design of the mr valve. the proposed mr valve provided an optimal h value. the τ was calculated using equation 3 and the b acquired from the femm program (τ =47kpa). figure 9 and table 1 illustrate the emulation results for the mr valves. when the puncture thickness (g ) is 0.5 mm, as a function of valve gap distance, figure 9 shows the “magnetic flux density induced by various currents in mr valve coils. the magnetic flux lines are perpendicular to the mr fluid’s flow in this case”. the magnetic flux density was practically constant at the valve gap distance and dropped as the current of the valve coils increased. the styling of the valves was considered to maximize the magnetic domain’s controllability. the maximal magnetic domain did not transcend the magnetic field's saturation strength. table 1 depicts the influx in mr valves as a function of current variation beneath various pressure reductions. the flow rate of mr valves increases as the current increases, indicating that they are primarily impacted by magnetic domains, which are specified by the coil current. it's worth noting that the flow rate rises in lockstep with the current until it reaches 2.5 a. by looking at pressure decline curves, it's clear that when the pressure drop is 650 kpa, the mr fluid isn't flowing at a current 2.5 a. as a result, because the valve can open at maximum current, a 650 kpa operational pressure decrease is adopted (2.5 a). by adjusting the current value, the mr valve can hadeer ali kamal al-khwarizmi engineering journal, vol. 17, no. 4, p.p. 1222 (2021)   18 be controlled with a variable flow rate ( q): a high current for a high flow rate, and a low current for a low flow, as shown in figure 10. the experiment explained how a valve works and how the proposed electrical connection can be used to change the flow direction. fig. 7. the nc mr valve magnetic flux intensity result. fig. 8. the nc mr valve magnetic field strength result. hadeer ali kamal al-khwarizmi engineering journal, vol. 17, no. 4, p.p. 1222 (2021)   19 fig. 9. the magnetic flux intensity (b) along the mr valve gap. fig. 10. relation between flow rate and pressure drop for different currents. table 1, the relation between current, magnetic flux intensity, pressures, and shear stress to mr valve current (a) magnetic flux density (b) (tesla) shear stress 𝛕𝐲 pressure (bar) 0 0.899 47.1488 18.8 0.5 0.765 38.4553 17.07 1 0.535 30.23 12.09 1.5 0.325 15.9 6.36 2.5 0.064 1.626 0.65 the mr valve has a changeable flow rate (q) that is controlled by adjusting the current value; a high current equals a high flow rate and vice versa. when the current is 0 a, the valve closes due to the magnetic field generated by the permanent magnet, and the magnetic flux intensity value is a maximum of 0.9, preventing it from flowing. when the current is 2.5a, the b 0.325, which allows the mr fluid to flow. the magnetic flux values that were acquired from the femm software are given in figures 11,12, and 13, and show a reasonable relation between the current and flow rate and pressure drops. hadeer ali kamal al-khwarizmi engineering journal, vol. 17, no. 4, p.p. 1222 (2021)   20 fig. 11. magnetic flux density(b) in femm software when i=0a. fig. 12. magnetic flux density(b) in femm software when i=2.5a. 7. conclusion the structure and operating norms of a singular valve that is generally closed without moving components and can be controlled by the properties of the magnetic fluid are covered in this paper. the valve has a total length of 19 mm. it has a 400-turn coil, a powerful neodymium (ni) magnet, and a 2 mm effective gap along its length. the magnetic flux density (b) is obtained when applying different values of the current, as the flow rate increased with the increase in the value of the current and the relationship was proportional between current and flow rate, and the value of the pressure decreased with the increase in the current, implying that the pressure and the current had an inverse relationship. the valve was tiny in size, and the valve coil was outside the effective region, allowing it to be easily replaced if it was damaged. different values of the magnetic flux in the gap of 2 mm were determined from the simulation using the finite element analysis in the femm program. when the valve is closed and the current value is zero, an ideal magnetic flux density (b) of around 0.9 teslas is obtained. when the current is 2.5 a, the valve is fully open and has maximum flow, where the magnetic flux density (b) value is 0.0653 teslas.   8. references   [1] “john2008.pdf.” . [2] m. y. salloom and z. samad, “design and modeling magnetorheological directional control valve,” j. intell. mater. syst. struct., vol. 23, no. 2, pp. 155–167, 2012, doi: 10.1177/1045389x11432654. [3] g. hu, m. liao, and w. li, “analysis of a compact annular-radial-orifice flow fig. 13. reasonable relation between current and flow rate and pressure drops. hadeer ali kamal al-khwarizmi engineering journal, vol. 17, no. 4, p.p. 1222 (2021)   21 magnetorheological valve and evaluation of its performance,” j. intell. mater. syst. struct., vol. 28, no. 10, pp. 1322–1333, 2017, doi: 10.1177/1045389x16672561. [4] m. y. salloom and z. samad, “magnetorheological directional control valve,” international journal of advanced manufacturing technology, vol. 58, no. 1–4. pp. 279–292, 2012, doi: 10.1007/s00170011-3377-4. [5] j. xie, c. liu, and d. cai, “analysis and experimental study on rheological performances of magnetorheological fluids,” mechanika, vol. 26, no. 1, pp. 31–34, 2020, doi: 10.5755/j01.mech.26.1.25244. [6] y. zhang, d. li, h. cui, and j. yang, “a new modified model for the rheological properties of magnetorheological fluids based on different magnetic field,” j. magn. magn. mater., vol. 500, no. september 2019, 2020, doi: 10.1016/j.jmmm.2019.166377. [7] g. hu, f. zhou, and l. yu, “optimal design and performance analysis of radial mr valve with single excitation coil,” actuators, vol. 10, no. 2, pp. 1–32, 2021, doi: 10.3390/act10020034. [8] r. l. lawson and a. m. sorensen, “ablation of the coagulating gland and subsequent breeding in the albino,” journal of reproduction and fertility, vol. 8. pp. 415– 417, 1964, doi: 10.1530/jrf.0.0080415. [9] v. t. thieu et al., “signal transducer and activator of transcription 4 is required for the transcription factor t-bet to promote t helper 1 cell-fate determination,” immunity, vol. 29, no. 5. pp. 679–690, 2008, doi: 10.1016/j.immuni.2008.08.017. ) 2021( 1222، صفحة 4العدد، 17مجلة الخوارزمي الهندسية المجلد هدير علي كمال 22 صمام تحكم اتجاهي مغناطيسي مغلقاً في حالة الطبيعة ال يسمح بمرور السائل تحليل ** ماهر يحيى سلوم *هدير علي كمال جامعة بغداد /كلية الهندسة الخوارزمي /الميكاترونكس هندسة قسم،*** hadeer.a.aljuboury@gmail.com :البريد االلكتروني* drmahir@kecbu.uobaghdad.edu.iq :البريد االلكتروني** ____________________________________ __________________________ الخالصة مغلقاً في حالة الطبيعية ال يسمح بمرور تم العمل في هذا البحث عن طريق تحليل العناصر المحدودة للوصول الى أفضل تصميم لصمام تحكم اتجاهي ا المغناطيسي وقوة التدفق بين كثافه تم خلق مجال الريولوجية المغناطيسية السائل الى اجزاء متحركة، من خالل صفات الحاجة ان ، لسوائلالسائل دون تصلب السائل المغناطيسي عند غياب التيار الكهربائي، حيث اظهرت الهدف الرئيسي من هذه الدراسة هو الوصل لكثافة فيض مغناطيسي مناسبه تتسبب في حجم لتصغير امكانيات التصميم هذا وفر مما التيار زيادة عند تدريجيا السائل جريان في التحكم على قادر الصمام ان التجريبية الصمامات النتائج ية. تخدامه للتحكم في اتجاه وسرعة المشغالت الهيدروليكالهيدروليكية، الغاء االجزاء المتحركة، باإلضافة الى قدره على اس __________________________ _______________________________ <4d6963726f736f667420576f7264202d20ddc7cae420e6d3e6d3e420e6dae1c7c120c7e1cfede439322d20313035> al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 15, no. 3, sptember, (2019) p. p. 92105 fuzzy analytical hierarchy process for embedded risk reduction in selecting the right planning decision faten f. abdul-razaq* sawsan s. al-zubaidi** allaeldin h. kassam*** *,**,***department of production engineering and metallurgy/ university of technology/ baghdad/ iraq *email: fatinfuad.87@gmail.com **email: sawsanaa2006@gmail.com ***email: allakassam@yahoo.com (received 20 march 2019; accepted 21 july 2019) https://doi.org/10.22153/kej.2019.07.005 abstract the aim of this work is to provide an efficient selection technique as a part of planning process to guide the decision makers to decide the preferences of one supplier over another for purchasing lab instruments in education domain. fuzzy analytical hierarchy process has used as a multi-criteria decision process, as an industrial engineering tool with certain emphasis on the qualitative aspects required to the decision makers. while the concept of degree of possibility for each criterion is used to reach its relative weights, a specific methodology created to reach the final objective decision of supplier selection. a questionnaire form was developed and distributed to five universities located in baghdad province with a total number of 100 questionnaires. the response was very adequate. three main criteria are adoptedsupplier, instruments and service performance grade. moreover, there are sixteen sub-criteria for evaluating three potential suppliers. the final decision is reached with almost risk-free as it relates to the qualitative aspects of experts. the conclusion reached is that local supplier has a large priority weight. microsoft excel is used to achieve the sequential calculations for fuzzy ahp. keywords: supplier selection, multi criteria, fuzzy analytical hierarchy process, risk reduction, qualitative aspects. 1. introduction there is abundant analysis within the literature that describes the matter of risk reduction from different perspectives, depending on the nature of problem addressed, all can be considered as a step of the planning process. however, research in this area continues to depend on the nature of use, sensitivity, and appropriateness of different types of organizations. therefore, dealing with this problem from the perspective of multiple criteria, and objectives are required carefully investigate to reach the goal sought by the decision maker. hence, supplier selection is a comprehensive problem relating qualitative and quantitative multi-criteria where risk is embedded during the decision process. supplier selection, as defined by boran and et.al [1] is “the process of finding the right suppliers who are able to provide the buyer with the right quality products and/or services at the right price, at the right time and in the right quantities”. on the other hand, it is a hard problem since supplier selection is typically a multi criteria group decision-making problem involving several conflicting criteria on which decision maker’s knowledge is usually vague and imprecise. analytical hierarchy process (ahp) can be considered as a multi criteria decision making faten f. abdul-razaq al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 92105 (2019) 93 (mcdm) tools to deal with risks associate with decision process. the ahp separates the evaluation decision into hierarchy levels and attempts to reduce the inconsistencies in human judgment developed by saaty [2] consequently ahp importance raised from its ability to cope with both qualitative and quantitative data and spread over wide application areas as mentioned by franek & kresta [3].the most critical issue of ahp related to other decision making approaches is its ability to use private individual judgments of decision maker as a focus of qualitative side [4], [5]. ahp method is based on mathematical tools for the processing of personal subjective preferences of the expert or a group of experts on the pairs of relevant factors formulated as comparative matrix assessing and analyzing decisions [6]. the ahp method works on the premise that the process of making a global decision on complex tasks can be performed by separating and structuring complex tasks into many simple tasks, displaying them in the form of hierarchical structure fig. 1. in its turn, after the hierarchical structure is formed, the pairwise comparison of assessment factors is carried out according to the importance on a lower level of the hierarchy. the results of pairwise comparisons are displayed by numbers related to specific application ranging from two extreme points i.e. from starting evaluation to final one. whereas starting means that the two evaluation factors reflected by linguistic value as equally important, while the other extreme rating reflects the fact that one assessment factor is absolutely more important than the other. while the in between these two extremes are other division of evaluation. next, the pairwise comparison of alternatives for each of the criteria factors is carried out. then, the obtained estimates are translated to the next level i.e. mid-level which dealing with criteria assessment, where the aggregation of previously obtained estimates is performed [7].thereafter, the interim assessments are transferred to the upper level of the hierarchy i.e. the level of goal /objective. the final aggregation of previous estimates is reached which reflects the resultant estimation for each alternative decision. the selection of the optimal solution is evaluated based on comparison of these estimates. fig. 1. ahp hierarchical structure (oguztimur, 2011). this paper is dealing with multi criteria decision process concentrated on selection of proper supplier for purchasing laboratory equipment required by scientific departments which facing a critical issues due to the absence of systemic scientific procedure. the current process is highly depends on personnel criteria parameters not relays on scientific formulated procedure. since this process is carry out in a non-profit environment. fuzzy ahp is proposed to solve such type of problem which heavily depends on the opinions of related experts in the fields. special questionnaire format are used as a basis of the qualitative part of the proposed tool. rest of this work is organized as follows. in section 2, criticism of ahp is given. section 3 presents detailed description of fuzzy mcdp. synopsis of related literature review is covered in section 4. problem issues are detailed in section 5. then research methodology is the focus of faten f. abdul-razaq al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 92105 (2019) 94 section 6. in section 7, numerical calculations for supplier selection problem is demonstrated. finally results and conclusion of the work is presented in section 8. 2. criticism of ahp in the conventional shape of ahp, human’s judgments area unit depicted as exact or crisp numbers. however, in several sensible cases the human preference model is unsure and decisionmakers can be reluctant or unable to assign exact numerical. in light of this, some shortcomings as mentioned by kabir and et.al. [9] of the application of saaty's ahp were heightened as follows: 1. the ahp technique is especially employed in nearly crisp decision applications. 2. ranking of the ahp methodology is quite general. the ahp method creates and deals with a very unbalanced scale of judgment. 3. the ahp technique doesn't take into consideration the uncertainty related to the mapping of one's judgment to variety. 4. the ahp technique creates and deals with a really unbalanced scale of judgment. 5. the subjective judgment, choice and preference of decision-makers have an enormous influence on the ahp outputs. additionally, decision-makers need on evaluating alternatives invariably contain ambiguity and multiplicity of which means. moreover, it has additionally recognized that the human assessment of qualitative attributes is usually subjective and therefore general. ahp can't satisfactorily cope with the imprecision and uncertainty in to be had information and in decision maker’s alternatives. human judgments whether or not they are quantitative or qualitative have a few inherent uncertainties in realistic eventualities because of distinct non-public perceptions. experts may additionally be reluctant to assign actual numerical values whilst evaluating parameters. in multi criteria decision making mcdm, assessment standards are each subjective and quantitative relying upon nature. the consulted databases additionally consist of positive imprecision as a few approximations may additionally be concerned inside the instruction of this type of database. good decision-making procedure ought to be capable of consider this normal fuzziness to keep away from deceptive consequences. therefore, the standard ahp looks inadequate to capture the choice maker's needs expressly regardless of the wider application and ease of its concept, and can not exactly deal with this inherent vagueness and uncertainty [10]. consequently, it's requiring the adoption of fuzzy logic with ahp method. 3. fuzzy multi criteria decision making in dissimilarity fuzzy multiple criteria decision-making (fmcdm) is the method of ranking the possible alternatives and choosing the most effective one by considering multiple criteria, during which the alternatives and criteria values are carried by completely different fuzzy sets belongs to fuzzy theory [11], like triangular fuzzy range [12], triangular intuitionist fuzzy range [13], and many others found in [14] [15], [16]. meanwhile, there are different ways of dealing with the fuzzy deciding issues, for instance, fuzzy ahp methodology [17], fuzzytopsis methodology [18], and distinguished other researchers focus on alternative strategies and might be remarked to [18], [19] [10] and etc. generally, to model uncertainty in human preference, fuzzy sets might be incorporated with the pairwise comparison as an associate extension of ahp. fuzzy ahp, comes into implementation to beat the counteractive approach and also the inability of the ahp in handling linguistic variables. the fuzzy ahp approach permits an additional correct description of the decisionmaking method. the fuzzy ahp tool may be viewed as a superior analytical methodology developed from the standard ahp. therefore, it's not possible to mirror the choice makers’ unsure preferences through crisp values. therefore, fuzzy ahp is projected to alleviate the quality of the ahp methodology, wherever the fuzzy comparisons ratios are used [9]. for simplicity, the structure of fuzzy ahp phases is depicted in fig. 2. because the triangular fuzzy number (tfn) is intuitive, straightforward to use, computationally easy, and helpful in promoting illustration and data process in a very fuzzy situation, it had been usefully applied to resolve fmcdm issues, within which the criteria values are implemented by the tfns. several methods are projected to resolve fmcdm with tfns within the literature. faten f. abdul-razaq al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 92105 (2019) 95 fig. 2. the outline structure of fuzzy ahp. the component as pointed out by zhang and et.al. [21] models of the tfn, and the related formulas are given below with the assistance of fig. 3. [22]. a triangular fuzzy number is represented as (l/m, m/u) or simply as (l, m, u). the parameters l, m and u respectively indicate the lowest possible value, the mode value and upper hopeful value that describe a fuzzy event. each tfn has linear representations on its left and right aspect such its membership function may be outlined as: µ�� � ⎩⎨ ⎧ 0 ̹ x � 1�x � 1� �m � 1�⁄ ̹ 1 � x � m ̹�u � x� �u � m�⁄ ̹ m � x � u ̹0 ̹ x � � ⎭⎬ ⎫ a fuzzy number m� will invariably incline by its corresponding left and right illustration of every degree of membership m� � �m���� ̹ m����� m� � �1 �m � 1�y ̹ u �m � u�y� ̹ y ∈ #0 ̹1$ where: l(y) and r(y) denotes the left side illustration and the right side illustration of a fuzzy number respectively. fig. 3. triangular fuzzy number representation. 4. related works because of the importance of selecting suppliers of product for certain applications, it has been the subject of great importance by researchers who uses fmcmd in different ways depending on the nature of the case. so the focus used in this vital area still addressing the fact that the majority research is concerning a particular case study of the qualitative aspect. çakır [24] recognized robust supplier selection algorithm based on the hybrid use of a modified fuzzy ahp and generalized choquet fuzzy integral (gcfi) methods at a steel company. the weights of the evaluation criteria were obtained from fuzzy ahp and then gcfi was used to achieve the overall performance values of supplier alternatives. he also showed the robustness of the devised methodology through a sensitivity analysis. he concluded that the proposed integrated approach can effectively handle supplier selection and other mcdm problems especially when there are interdependent sub-criteria in a complex hierarchy of evaluation criteria. galankashi and et.al. [25] proposed an integrated new balanced scorecard–fuzzy analytic hierarchical process (bsc–fahp) model to pick out suppliers within the automobile industry. information was gathered employing a literature survey and accredited using nominal group technique. finally, a fuzzy ahp was used to select the best supplier. also, within the same environment of an industrial automobile, jain [26] was applied fuzzy ahp and topsis for supplier selection as a tool for fmcdm approach. the faten f. abdul-razaq al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 92105 (2019) 96 selection process starts with identifying the criteria based on literature review and interviewing industry experts. weights to criteria are assigned using ahp, and suppliers are ranked using ahp and topsis. consistency tests are carried out to check the quality of expert’s inputs. also, sensitivity analysis is done to check the robustness of the approach. the results address that fuzzy approaches could be effective and more accurate than the existing approaches for supplier selection problems. regarding to pair wise comparison scale based on triangular fuzzy numbers chang [27] introduced a new approach of extent analysis method for synthetic extent value of the pair wise comparison. the first step in this method is to use tfns for pair wise comparison by means of fahp scale, while using synthetic extent values to obtain priority weights through fuzzy evaluation matrix of the criteria of different attributes relevant to the overall objective. the trade-off between tangible and intangible factors which conflict with each other was the focus of gurung & phipon [28]. the purpose of their paper is to evaluate the suppliers in supply chain cycle using ahp and topsis. factors such as product quality, facility, delivery time and price have been taken into consideration while evaluating the suppliers in this supplier selection process. in the same sense of supply chain intuitionistic fuzzy topsis method is proposed by boran and et.al. [1] to select appropriate supplier in group decision making environment. intuitionistic fuzzy weighted averaging operator is utilized to aggregate individual opinions of decision makers for rating the importance of criteria and alternatives which was illustrated by a numerical example. santis [29] presents a decision model based on the fuzzy ahp tool of maintenance supplier selection in a large brazilian railway operator for evaluating 5 different suppliers. eight criteria were adopted technical capacity, financial status, relationship, operations management, security management, infrastructure, historic performance and costs. fuzzy ahp was used by kahraman and et.al. [22] to compare the supplier firms. choosing the best qualified supplier firm providing the foremost satisfaction for the factors determined. the purchasing managers were interviewed and therefore the most vital criteria taken under consideration by the managers were determined by a questionnaire. researchers conclude a very important point in this area is that decisions are made today in more and more complex environments, choices are created nowadays a lot of in additional and more advanced environments, therefore the employment of experts opinions in numerous fields is critical, different criteria values of the systems are to be taken into consideration and consequently fuzzy multi criteria decisionmaking will overcome this problem. health care sector has also been included in the supplier selection process as beşkese & evecen [30] proposed a hierarchical structure model specific to the sector, and the criteria within the model were prioritized by considering the evaluations of the managers of 6 well-known healthcare organizations in turkey. risk prioritization based on their threat level was the focus of lópez & salmerón [31] by proposing a modernized ahp method. while radionovs & rebrovs [32] assumed risk factor as an element of lower level of the hierarchical structure and is expressed as a fuzzy number in fahp, which is the combination of fuzzy evaluation of the probability of a corresponding adverse event and the fuzzy evaluation of potential losses related to the implementation of this event. 5. problem description the main problem of this study is the decision support process to supply laboratory instruments to the university departments derived from supplier selection. the decision-making process for purchasing laboratory instruments considered an important and necessary process because it depends directly on the requirements restricted by certain qualitative parameters as well as on the supplier flexibility under restricted parameters and variables. most of the purchasing of laboratory equipment based on personal relationships without relying on the efficiency and quality of the instrument. additionally, there are many others obstacles facing decision-makers when selecting reliable and experienced suppliers at organizations such as universities that are a nonprofit organization under restricted budget and facing a different kind of risks. so that adopting fuzzy ahp as a tool for solving the fuzzy multicriteria decision-making problem is the axis of this study. qualitative criteria should be determined by experts directly interacting with the core of the problem. therefore, a specific methodology is required to reach the final objective decision of supplier selection based on almost risk-free in the form of qualified, reliable and effective laboratories equipment. since the faten f. abdul-razaq al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 92105 (2019) 97 embedded risk is due to the failure of the process of selection right supplier, right required equipment, and reliable cost. consequently, the qualitative side of the fahp tool is one major issue of the problem. 6. research methodology fuzzy ahp is used to generate the weighting of the criteria perspectives and the weighting of the performance indicators. fuzzy ahp is used to assist decision-making process based on the best and most suitable supplier selection objective. the objective in this specific problem are structured around three related criteria: supplier (sc), instruments (ic) and service performance (sp) grade that which considered in making selection decision of adequate and reliable supplier in order to satisfy restrictions carefully involved in the second level. thereafter constructing the third level of the process contains sub-criteria for each one involved in the previous level. these subcriteria includes (quality and safety sc1, information sharing sc2, flexibility and responsiveness sc3, social responsibility sc4, and experience sc5) which belong to the supplier criteria. while the instruments criteria can be classified into (disposable or reusable ic1, source ic2, cost ic3, use and maintenance ic4, quality assessment techniques ic5, and product reliability ic6); then finally the sub-criteria of service performance are (delivery lead time sp1, offers sp2, technical support sp3, value added sp4, and operating cost sp5). from these sub-criteria three alternative suppliers which are denoted as (local, internal and external and represented as s1, s2, and s3 respectively) for the purpose of this research are chosen. the outline of the hierarchy structure of the adopted decision process of the fuzzy ahp is illustrated in fig. 5. the key research approach involved in this work for adopting the fuzzy ahp method is centered on the corresponding questionnaires developed and distributed to three different kinds of category experts. firstly, senior scholar lecturers and adjunct research fellows from the field that are involved directly in using the lab equipment to assist the students to accept and understand the purpose of using the device and thus expand their understanding in the mode of interaction and development. secondly, from purchasing managers and administrative officers who know the capabilities and restriction of expansion during periods of time and finally from financial affairs depending on five universities located in baghdad province with a total number of 100 and the response was very adequate. while the concept of the degree of possibility for each criterion is used to reach the relative weights. the qualitative aspect of the methodology is concentrated on the linguistic importance scale defined by the related experts. accordingly triangular fuzzy scale is used for criteria selection beginning by fuzzy crisp values (1,1,1) for criterion has exactly the same importance (i). then the scale start to vary from one criterion to another by step 0.5 and according to its significance of intersection between five observed scales which is ending by absolute importance (v) as shown in table 1. and clarified by fig. 4. table 1, linguistic importance scale. linguistic importance scale triangular fuzzy scale inverse of triangular fuzzy scale exactly the same (i) (1,1,1) (1,1,1) slightly important (ii) (1,1.5,2) (0.5,0.67,1) serious importance (iii) (1.5,2,2.5) (0.4,0.5,0.67) more serious importance (iv) (2,2.5,3) (0.33,0.4,0.5) absolute importance (v) (2.5,3,3.5) (0.3,0.33,0.4) faten f. abdul-razaq al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 92105 (2019) 98 fig. 4. linguistic variables for the importance weight scale. fig. 5. hierarchy structure for decision process of selecting best supplier. a questionnaire was designed with fuzzy ahp format (five-point scale and pairwise comparison) based on the hierarchy of fig. 5. the questionnaires are to obtain the preference weights among main-attributes, sub-attributes and alternatives. the main attributes determined by the pair wise questionnaire were given to the experts and requested to fill up by identity relative importance between the three decision criteria. one hundred questionnaires are distributed to the three involved expert's categories. the number of valid questionnaires was 89 (89%). thereafter, the responses collected from questionnaires are input to the fuzzy ahp procedure explained later. all valid responses were collected and recorded. hence, the data in table 2. is based on an expert’s opinion. the structures of the adopted methodology for the multi-criteria decision-making process of supplier selection for lab critical instruments based on fuzzy ahp are summarized as in fig. 6. faten f. abdul-razaq al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 92105 (2019) 99 fig. 6. methodology of the fuzzy ahp. the procedure of using the mentioned methodology is given below with brief description of related steps (chang, applications of the extent analysis method on fuzzy ahp, 1996): step 1: create the hierarchy structure of the problem as clarified in fig. 5. steps 2, 3 and 4: generate the fuzzy comparison matrix with respect to the objective, main criteria and sub-criteria depending on the create hierarchy structure generate criteria comparsion matrix with respect to objective generate sub-criteria comparsion matrix with respect to each criteria generate alternatives comparsion matrix with respect to each sub-criteria determine the degree of possibility for each matrices decide the minimum degree of possibility of the distinction of each criteria over another determine the weight vectors of the criteria acoording to step 6 normalizing weight vectors and determine authority of decision criteria with respect to the objective calculate the final weight for all sub-criteria by repeating steps 5-8 multiply the priority weights of alternatives with the sub-criteria and decide the priority of the alternatives with respect to the main criteria multiply the priority weights of the decision alternatives with priority weight of criteria and decide the final priority of the decision alternatives with respect to the primary objective select the best supplier with the highest priority weight step 5 step 8 step 10 step 11 step 9 step 7 step 6 step 4 step 3 step 2 step 1 faten f. abdul-razaq al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 92105 (2019) 100 opinion of the distinguished experts at five universities located at baghdad as an instrument of study. step 5: degree of possibility (fi) for the fuzzy comparison matrix with respect to objective is calculated by multiplication of summation (lower, mode and upper value) horizontally by the summation (upper, mode and lower value) vertically, as clarified in equations below (chang, applications of the extent analysis method on fuzzy ahp, 1996): where: i= 1,2,3 ……… n (no. of row). j=1 ,2,3 ………..m (no. of column). %& = degree of possibility which is used to compare between criteria. ∑ a)*+,� = summation (lower, mode and upper value) for each column of comparison matrix. #∑ ∑ -.$/0,�1&,� 2� = summation (lower, mode and upper value) for each row of comparison matrix; and can be called the inverse summation of data. %& � ∑ 3. × #∑ ∑ -.$/0,�1&,� 2� /0,� … (1) ∑ 3./0,� � #∑ 3�0 ̹ ∑ 350 ̹ ∑ 360/0,� $/0,�/0,� … (2) #∑ ∑ -.$/0,�1&,� 2� � # � ∑ 789:9;8 ̹ � ∑ 7<9:9;8 ̹ � ∑ 7=9:9 ] …(3) step 6: the degree of possibility of criteria %� when comparing with other degree of possibility of criteria %5; if it’s greater than or equal, the degree of possibility equal 1, but if it’s smaller than then we use eq. (4) where (>) refer to the result of compare degree of possibility. > � �%5 ≥ %�� � @ 18821<=�1<<21<=�2�18<2188�a … (4) after that, we decide the minimum degree of possibility where refer to by symbol (b&) to compare each results with other one as shown in eq. (5) b& � min >�%� ≥ %5 , %6 … … . %1) … (5) step 7: weight vector of each criteria calculated by dividing the minimum degree of possibility by summation of the minimum degree of possibility. h& � i&1 j9∑ i&1 j9:9 … (6) where: i= 1,2,3………n. k= (w1, w2, w3, ……..n) step 8: normalizing the weight vector and decide the final weight for all subcriteria. step (9) & step (10): multiplying the priority weights of alternatives with the sub-criteria and decide the priority of the alternatives with respect to the main criteria. furthermore multiplying the priority weights of the decision alternatives with priority weight of criteria and then decide the final priority of the decision alternatives with respect to the primary goal. step 11: select the highest priority weight as the best supplier. 7. numerical calculations for supplier selection to clarify the steps of the methodology for laboratory apparatuses supplier selection process through sample of calculation that extracted from the related tables (2 9). microsoft excel version 10 was used to make numerical calculations for this study, a snapshot as an example is shown in fig. 7. as a starting point, we need to use table 2. extracted from questioners data to illustrate the numerical calculations: no. of rows i= 3, and no. of columns j=3 . using eqs. (1, 2, and 3) in step 5 then: f1 = (1.73, 1.9, 2.17) × (12.67, 10.57, 8.73) -1 = (21.9191, 20.083, 18.9441) f2 = (3.5, 4.17, 5) × (12.67, 10.57, 8.73) -1 = (44.345, 44.0769, 43.65) f3 = (3.5, 4.5, 5.5) × (12.67, 10.57, 8.73) -1 = (44.345, 47.565, 48.015) the degrees of possibility of f1 over f2 & f3 are compared (step 6), if f1 ≥ f2, f3 the result equal 1 otherwise we used eq. (4) as shown below: c�f� ≥ f5� � nn.6on 2�p.qnn� �5r.rp62�p.qnn��2�nn.rstq2nn.6no� = =18.05323 c�f� ≥ f6� � 12.2055 c�f5 ≥ f�� = 1, c�f5 ≥ f6� = 1 c�f6 ≥ f�� =1, c�f6 ≥ f5� = 1 then the minimum degree of possibility is found by comparing each result with other using eq. (5) p� � min c (18.05323, 12.2055) = 12.2055. similarly, p5 � min c�f5 ≥ f� , f6) = 1 p6 � min c�f6 ≥ f� , f5 ) =1 so that, the minimum is p = 1 weight vector of main criteria (step 7) is approached by eq. (6) w� � �5 �n = 0.857, w5 � 0.071, w6= 0.072 w = [0.857, 0.071, 0.072] t faten f. abdul-razaq al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 92105 (2019) 101 the fuzzy comparison matrix with respect to overall objective with weight vector is given in table 2. from table 2 noticed the fuzzy comparison matrix with respect to overall objective which is debriefed from experts knowledge; after that we applied numerical calculations and normalizing a priority weights for each criteria. table 2, fuzzy comparison matrix with respect to overall objective. o sc ic sp weights sc (1,1,1) (0.33,0.4,0.5) (0.4,0.5,0.67) 0.857 ic (2,2.5,3) (1,1,1) (0.5,0.67,1) 0.071 sp (1.5,2,2.5) (1,1.5,2) (1,1,1) 0.072 similarly; same steps are applied to calculate priority weights of fuzzy pair wise comparison matrix for sub-criteria of supplier (sc), instruments (ic) and service performance (sp) as revealed in tables 3, 4, and 5 respectively table 3, fuzzy comparison matrix of supplier criteria. sc sc1 sc2 sc3 sc4 sc5 weights sc1 (1,1,1) (0.5,0.67,1) (0.33,0.4,0.5) (0.4,0.5,0.67) (0.5,0.67,1) 0.132 sc2 (1,1.5,2) (1,1,1) (0.4,0.5,0.67) (0.5,0.67,1) (0.3,0.33,0.4) 0.242 sc3 (2,2.5,3) (1.5,2,2.5) (1,1,1) (0.3,0.33,0.4) (0.4,0.5,0.67) 0.142 sc4 (1.5,2,2.5) (1,1.5,2) (2.5,3,3.5) (1,1,1) (0.5,0.67,1) 0.252 sc5 (1,1.5,2) (2.5,3,3.5) (1.5,2,2.5) (1,1.5,2) (1,1,1) 0.232 table 4, fuzzy comparison matrix of instruments criteria. ic ic1 ic2 ic3 ic4 ic5 ic6 weights ic1 (1,1,1) (0.4,0.5,0.67) (0.5,0.67,1) (0.4,0.5,0.67) (0.3,0.33,0.4) (0.33,0.4,0.5) 0.163 ic2 (1.5,2,2.5) (1,1,1) (0.33,0.4,0.5) (0.3,0.33,0.4) (0.4,0.5,0.67) (0.3,0.33,0.4) 0.157 ic3 (1,1.5,2) (2,2.5,3) (1,1,1) (0.5,0.67,1) (0.33,0.4,0.5) (0.5,0.67,1) 0.145 ic4 (1.5,2,2.5) (2.5,3,3.5) (1,1.5,2) (1,1,1) (0.33,0.4,0.5) (0.4,0.5,0.67) 0.194 ic5 (2.5,3,3.5) (1.5,2,2.5) (2,2.5,3) (2,2.5,3) (1,1,1) (0.5,0.67,1) 0.168 ic6 (2,2.5,3) (2.5,3,3.5) (1,1.5,2) (1.5,2,2.5) (1,1.5,2) (1,1,1) 0.173 table 5, fuzzy comparison matrix of service performance criteria. in the same way, calculation weights vector repeated 16 times for fuzzy pair wise comparison matrixes of alternatives with respect to five subcriteria of supplier (sc), six sub-criteria of instruments (ic), and five sub-criteria of service performance (sp) based on fig. 4 and as given by tables 6, 7, and 8 respectively. table 6, summary of priority weights for sub-criteria of supplier. sp sp1 sp2 sp3 sp4 sp5 weights sp1 (1,1,1) (0.33,0.4,0.5) (0.3,0.33,0.4) (0.4,0.5,0.67) (0.3,0.33,0.4) 0.216 sp2 (2,2.5,3) (1,1,1) (0.5,0.67,1) (0.33,0.4,0.5) (0.4,0.5,0.67) 0.167 sp3 (2.5,3,3.5) (1,1.5,2) (1,1,1) (0.4,0.5,0.67) (0.3,0.33,0.4) 0.235 sp4 (1.5,2,2.5) (2,2.5,3) (1.5,2,2.5) (1,1,1) (0.33,0.4,0.5) 0.186 sp5 (2.5,3,3.5) (1.5,2,2.5) (2.5,3,3.5) (2,2.5,3) (1,1,1) 0.196 sc1 sc2 sc3 sc4 sc5 alternative priority weights weights 0.132 0.242 0.142 0.252 0.232 alternatives s1 0.802 0.509 0.771 0.731 0.787 0.705 s2 0.096 0.258 0.121 0.138 0.181 0.169 s3 0.102 0.233 0.108 0.131 0.032 0.125 faten f. abdul-razaq al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 92105 (2019) 102 table 7, summary of priority weights for sub-criteria with instruments. ic1 ic2 ic3 ic4 ic5 ic6 alternative priority weights weights 0.163 0.157 0.145 0.194 0.168 0.173 alternatives s1 0.354 0.588 0.853 0.797 0.116 0.751 0.577 s2 0.132 0.198 0.121 0.181 0.099 0.236 0.162 s3 0.514 0.214 0.026 0.022 0.785 0.013 0.259 table 8, summary of priority weights for service performance sub-criteria with suppliers. thereafter, the final decision can be reached through developing priority weights of the three main criteria (sc, ic, and sp) with the three alternative (s1, s2 and s3) to reach the overall objective as mentioned in table 9 which shows that suppler s1 (local supplier) is the best decision to be selected. table 9, summary combination of priority weights: main criteria of the overall objective. sc ic sp alternative priority weights weights 0.857 0.071 0.072 alternatives s1 0.705 0.577 0.508 0.682 s2 0.169 0.162 0.300 0.178 s3 0.125 0.259 0.191 0.139 fig. 7. snapshot of calculations in excel window. sp1 sp2 sp3 sp4 sp5 alternative priority weights weights 0.216 0.167 0.235 0.186 0.196 alternatives s1 0.51 0.623 0.511 0.309 0.594 0.508 s2 0.34 0.243 0.371 0.235 0.282 0.300 s3 0.15 0.134 0.118 0.456 0.124 0.191 faten f. abdul-razaq al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 92105 (2019) 103 8. results and discussion the decision-making process pertaining to purchasing laboratory instruments from different suppliers for education purpose at the university level is considered an important and necessary process because it depends directly on the requirements restricted by certain qualitative and quantitative parameters. most of the purchasing of laboratory equipment based on personal relationships without relying on the efficiency and quality of the instrument. there are many obstacles facing decision-makers at universities when selecting reliable and experienced suppliers, as universities are nonprofit organizations under limited budget and facing a different kind of risks. the decision of selecting the supplier is a risky complicated process and is considered as a multi criteria decision process having a various priority weights extracted from expert’s opinions used to finalize the decision objective. one of the methods used to solve such problems are fahp outcome represented in table 9. indicates that supplier (s1) who is the local supplier has a large priority weight (0.682) which means the most suitable supplier according to the qualitative aspects of reliable experts in the field. three main criteria were the focus of the study. these are supplier, instruments and service performance criteria. each is divided into sub criteria with a total of sixteen. the pairwise comparisons with five scales linguistic values are used. each of them is reflected by three fuzzy values (min, mode, high). the step from one value to the next is at 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[32] andrejs radionovs and oļegs užga rebrovs, "fuzzy analytical hierarchy process for ecological risk assessment," information technology and management science, vol. 19, pp. 16–22, 2016. )2019( 92105، صفحة 3، العدد15دجلة الخوارزمي الهندسية المجلم فاتن فؤاد عبد الرزاق 105 صحيحال التخطيط قرارللحد من المخاطر المضمنة في اختيار المضبب عملية التحليل الهرمي عالء الدين حسن قاسم*** سوسن صبيح الزبيدي** فاتن فؤاد عبد الرزاق* العراق / بغداد /*،**،***قسم هندسة االنتاج والمعادن / الجامعة التكنولوجية .gmail.com87fatinfuad@البريد االلكتروني : * gmail.com2006sawsanaa@ البريد االلكتروني:** allakassam@yahoo.com البريد االلكتروني:* ** الخالصة دوات اللتوجيه صانعي القرار لتحديد تفضيالت مورد على آخر لشراء أ كجزء من عملية التخطيط اختيار فعالةالهدف من هذا البحث هو توفير تقنية مع كاداة في مجال الهندسة الصناعية عملية التحليل الهرمي المضبب كعملية اتخاذ قرار متعدد المعايير تفي مجال التعليم. استخدمالمستخدمة لمختبريةا انها النسبية. التركيز بشكل خاص على الجوانب النوعية المطلوبة لصانعي القرار. في حين يتم استخدام مفهوم درجة اإلمكانية لكل معيار للوصول إلى أوز نسخة على خمس جامعات في منهجية محددة تم إنشاؤها للوصول إلى القرار النهائي الموضوعي الختيار الموردين. تم إعداد استمارة استبيان وتوزيع مائة ، هناك ستة عشر ). عالوة على ذلكsp) وأداء الخدمة (ic) واألدوات (scالمورد ( -محافظة بغداد. وكانت االستجابة مقبولة. تم تبني ثالثة معايير رئيسية من المخاطر تقريبا باالعتماد على الجوانب النوعية التي اعتمدت معياًرا ثانوًيا لتقييم ثالثة موردين محتملين. ان القرار النهائي الذي تم التوصل اليه هو خالي ي عملية التحليل الهرمي استخدام برنامج االكسيل الجراء الحسابات المتسلسلة فبوان المجهز المحلي حصل على وزن اسبقية عالي من قبل الخبراء. المضبب. . al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 6, no. 2, pp 7282 (2010) land use/cover change analysis using remote sensing data: a case study, zhengzhou area, henan province, china bassam f. al-bassam faculty of environmental engineering, china university of geosciences, wuhan 430074, china; college of engineering/ al mustansirya university (received 19 july 2009; accepted 27 july 2010) abstract in the last two decades, arid and semi-arid regions of china suffered rapid changes in the land use/cover change (lucc) due to increasing demand on food, resulting from growing population. in the process of this study, we established the land use/cover classification in addition to remote sensing characteristics. this was done by analysis of the dynamics of (lucc) in zhengzhou area for the period 1988-2006. interpretation of a laminar extraction technique was implied in the identification of typical attributes of land use/cover types. a prominent result of the study indicates a gradual development in urbanization giving a gradual reduction in crop field area, due to the progressive economy in zhengzhou. the results also reflect degradation of land quality inferred from the decline in yield capacity and significant degeneration. developing land types are barren land and urban areas (8.02%, and 246.65%). shrinking land types are water, forest, crop, and grass areas (5.98, 11.52%, 7.09%, and 20.02% respectively). such changes are the results of physical and anthropogenic factors. the results are expected to provide very useful information for the local government in its future planning. key words: land use/cover change, laminar extraction technique, zhengzhou (china). 1. introduction changes in land use/cover are among the most important human alterations affecting the surface of the earth (lambin et al., 2001). land use represents the most substantial human alteration of the earth system in the past 300 years (vitousek et al., 1997). between one-third and half of the land surface has been transformed. land use/cover changes in china is powered by demand on food for its growing population (shanzhong qi and fang luo, 2006). research on controlling factors of lucc has recently been intense. song conghe et al., 2001, emphasized on monitoring and assessing large-scale ecological systems on basis of data derived from remote sensing images. lucc is strongly linked to growth in population, market development, technical innovation and policy action. turner et al., 1995, stated that changes in land use could have many consequences on natural resources. they listed such resources as alteration of vegetation cover, physical characteristics changes in soil, plant, and animal populations. similar statements were quoted by lambin et al., 1999 and aylward, 2000. significant land use/cover change took place in zhengzhou area over the past two decades by natural forces and human activities. no ground truth data available for land cover change in this area. the land use/cover classification system and remote image interpretation of characteristics were established in this study. the aim of the study was to document land use/cover change since 1988 using two sets of multispectral thematic mapper tm images (1988 and 2006). in order to identify the typical attributes of land use/cover types, a laminar extraction technique was used. the land is divided into six categories: water resources, forest, grass, barren, crop, and urban areas. these landscape attributes were individually extracted using multi-layered information extraction. applying empirical interpretation to combine the automatic computer classification and post this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ bassam f. al-bassam al-khwarizmi engineering journal, vol. 6, no. 2, pp 72-82 (2010) 73 classification has enhanced the image classification efficiency and accuracy. this procedure takes into consideration all the target features, avoiding the combinations of different attributes in a map. the outcome is a fusion of attributes into a color image for land use/cover classification. the accumulation of basic data on utility status and quantified dynamic change is now achievable. 2. study area zhengzhou is the capital city of henan province. it’s located in the lower reaches of the yellow river basin. the study area extends between the longitudes 112° 45′ 00″ e-114° 15′ 00″ e and the latitudes 34°10′00″ n-35°00′00″ n. it covers all of zhengzhou municipality, including zhengzhou city and its six constituent counties (figure 1). the total area of zhengzhou is 7,446.2 km2; the total population in zhengzhou is 7.2 millions, of which the rural population accounted for 62.8% (bsz, 2006). the total gdp of zhengzhou is 21.5×109 us $, of which only 4.4% derives from agriculture. therefore, the agricultural economy, despite the involvement of the majority of the population and a high fraction of the water use, accounts for a very low fraction of the total gdp in zhengzhou. fig.1. location map of zhengzhou area. as a whole, the elevation of the study area decreases from southwest to northeast. the highest peak is the shaoshi apex of songshan mountain with an elevation of 1494 m. the elevation is less than 200 m in the eastern plain, with the nadir located in haogang village in zhongmu county. (figure 2). this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ bassam f. al-bassam al-khwarizmi engineering journal, vol. 6, no. 2, pp 72-82 (2010) 74 fig.2. geomorphologic map of zhengzhou. zhengzhou area is a continental monsoon climate. the average annual temperature is about 14.3 ºc .the mean annual precipitation of zhengzhou is 641 mm and ranges from 751 mm in the south to 547 mm in the north, 65.0% to 67.2% of which is concentrated between june and september. the mean annual evaporation is 1016 mm. there are 35 rivers in zhengzhou area, such as yiluo river, shuangji river, jialu river, and yellow river. yellow river is the largest transit river (running across the northern border of the area) with mean annual runoff of 44.4×109 m3 at huayuankou hydrologic station. there are many reservoirs, of which 13 reservoirs are of medium size with storage of more than 10×106 m3. most surface water belongs to poor grade water quality (grade v or below v in chinese terminology, of which grade i is best and grade v is only applicable to agriculture irrigation). the surface waters have been polluted badly because of direct discharge of industrial and domestic wastewater. so, groundwater is the most important water supply source for urban and rural areas. 3. hydro-geologic conditions in zhengzhou area, the archaeozoic to neogene rocks are outcroped in the south and west mountain areas (approx. 50% of the study area). quaternary unconsolidated materials cover the north and eastern plains (figure 3). there are mainly three kinds of groundwater, karstic water in carbonate systems, water in fractured systems in hard and clastic rock, and primary porosity water in quaternary unconsolidated material. fractured rock systems generally have deep groundwater table depth and are relatively difficult to exploit. highly porous quaternary aquifers are widely distributed in the eastern plain (sun et al, 2007). the porous quaternary aquifers are the most important in zhengzhou. they can be divided into four more or less overlying sub-aquifers: shallow aquifer (unconfined aquifer less than 60 m deep), middle aquifer (confined aquifer 60-300 m deep), deep aquifer (confined aquifer 300-800 m deep) and super-deep aquifer (confined aquifer deeper than 800 m). the shallow aquifers have abundant groundwater because they can be easily recharged by precipitation, irrigation, rivers, and reservoirs. the confined aquifers, on the other hand, have abundant groundwater because of their huge extent and volume (li guirong, 2005). the tubewells for agriculture are mostly located in the eastern plain. because of the superposition of porous aquifers, the tubewells almost have several screens that are located in different sand or gravel layers (sun et al, 2007). this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ bassam f. al-bassam al-khwarizmi engineering journal, vol. 6, no. 2, pp 72-82 (2010) 75 fig.3. geologic map of zhengzhou. 4. materials and methods to detect changes in land use/cover during the 18-years period (1988-2006) using remote-sensing data, a new set of land use/cover categories was developed by modifying the us geological survey land use/cover classification system (chen 2002) applicable to the study area, including six classes (cropland, forestland, grassland, urban and/or built-up land, water, and barren land) and taking full account of these field investigations. the chosen classes were also based on amenability to accurate identification from the available imagery and ancillary interpretation resources. remote sensing based approaches have been followed in the present study. two landsat tm and etm+ satellite images from the same cropping period of the years 1988 and 2006 are utilized. the image processing techniques were implemented through erdas imagine software. preprocessing of the remotely sensed data has been applied prior to actual analysis to improve the quality of the data. image restoration involves the correction of distortion, degradation and noise introduced during the imaging process. radiometric and geometric errors are the most common types of error encountered in remotely sensed imagery. the radiometric and systematic geometric errors of landsat tm data have been removed by the commercial data provider, while the unsystematic geometric error remains in the image. the geometric errors of the lansat tm data were corrected by using ground control points before the analysis of land cover change. the study area which was cut from the two images covers about 7319.64 km2. figures (4) and (5) show the two times outcome images (1988 and 2006) resulted through a color composite technique. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ bassam f. al-bassam al-khwarizmi engineering journal, vol. 6, no. 2, pp 72-82 (2010) 76 fig.4. 1988 color composite image rgb (321) of the study area. fig.5. 2006 color composite image rgb (321) of the study area. aiming at developing a new classification method by making use of the spectral information acquired by a satellite, statistical analysis of data, and the ground truth information in training data; many algorithms (image processing techniques) have been applied. these are the selection of different band combinations for visual interpretation, principal component analysis this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ bassam f. al-bassam al-khwarizmi engineering journal, vol. 6, no. 2, pp 72-82 (2010) 77 (pca), and ihs decorrelation stretching. these algorithms are created to display the best contrast between different land use/cover attributes. in addition to that, sixty four points were selected to be cross checked in the field to make sure that the classification results are true. huete et al., 1988 amended a simple model presented by ndvi (normalized difference vegetation index) which is used to describe soilvegetation system according to the soil background’s sensitivity (soil-adjusted vegetation index): )1( l ldndn dndn savi rnir rnir          …(1) or: )1( l lrnir rnir savi            …(2) where: l is a soil-adjusted coefficient, it is a constant determined by the actual regional conditions to reduce vegetation index reflection of the different changes in the sensitivity of the soil. (when l is zero, savi is equal to ndvi). for medium vegetation cover, l generally is closer to (0.5). the factor (1 + l) is used mainly to ensure that the final values of savi and ndvi are ranged from (-1 ~ +1). other functions were derived based on the savi: tsavi= [a(nir-ar-b)]/(r+anir-ab) …(3) where a & b are the soil background parameters. in order to reduce the impact of savi in the bare soil, the modified soil-adjustment vegetation index was developed: 2/)(8)12()12( 2 rnirnirnirmsavi  …(4) it has been proved that savi and tsavi have more advantages in describing the vegetation cover and soil background. in the case of bare soil background, tsavi has a better sense of low vegetation cover than ndvi in semi-arid areas (wang qiao et al., 2005). savi and msavi were tested to detect the vegetation cover in the study area. msavi was more effective in identifying the boundaries between the barren lands and the vegetation areas in zhengzhou. many functions are created to identify each attribute in the image data. different thresholds values are tested for each attribute until the best limits were determined. table 1 shows the functions which are used to extract the different attributes. table 1. the reference table for extraction the information of each attribute. attribute 1988 2006 water (tm2+tm3+20－tm4－tm5 >0) and (tm3<110) and (tm5 < 70) from the raw data (tm2+tm3+50－tm4－tm5 >0) and (tm3 <90) and (tm5<50) from the raw data forest (msavi*1000 >230) and (dem >500) (msavi*1000 >230) and (dem >500) crop land (msavi*1000 >-300) and (msavi< 230) and (dem < 200) (msavi*1000>-300) and (msavi<230) and (dem < 200) urban area (tm2>tm5) and (tm5>tm7) and (100>tm7>80) and (120>tm5>80) and (80>tm4>60) and (130>tm3>90) and (110 >tm2>90) and (tm1>110) and (tm4tm3<15) from raw image (tm2>tm5) and (tm5 >tm7) and (100>tm7>80) and (120>tm5>80) and (80>tm4>60) and (130>tm3>90) and (110 >tm2>90) and (tm1>110) and (tm4tm3<15) from raw image grass land (msavi*1000>-600) and (msavi<-300) and (200<dem <500) (msavi*1000>-600) and (msavi<-300) and (200<dem <500) barren land (msavi*1000>-1000) and (msavi<-600) and (300 < dem) (msavi*1000>-1000) and (msavi<-600) and (300 < dem) comment: tm2, tm3, tm4, tm5, tm7 are the spectrum of tm bands in the raw image; dem=digital elevation model this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ bassam f. al-bassam al-khwarizmi engineering journal, vol. 6, no. 2, pp 72-82 (2010) 78 5. classification. a laminar extraction technique suggested by al bassam, 2007 was applied; the specific procedure is as follows: 1. the character of each object at each time is analyzed to identify the range values of each class. this is done for the whole bands by statistical analysis and the best bandcomposition for each attribute is reached; 2. extracting the high accuracy attribute by setting up the model toward some objects with large different spectral character; 3. the concerned area on the raw image is masked; 4. extracting other attributes by operating similar procession to step (1); the four steps above are repeated till all the objects are extracted. separation of land and water is attained through the process. water is then masked from raw image and separate vegetation from non-vegetation till the entire extraction of all objects is done. following the extraction of each object; the model could be set up to fuse the attributes into a colored image. this is considered as the outcome of land use/cover classification. in order to ensure classification accuracy, filtering and artificial corrections of some pixels is done to overcome the limitation of tm resolution factor and topography feature. the applied filtering algorithim was (3×3), whereas artificial amendments were carried out on basis of available geological and geomorphological maps (figures 6 & 7). fig.6. the 1988 land use/cover classification outcome image of zhengzhou area. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ bassam f. al-bassam al-khwarizmi engineering journal, vol. 6, no. 2, pp 72-82 (2010) 79 fig.7. the 2006 land use/cover classification outcome image of zhengzhou area. 6. results and analysis figure 8 and table 2 show the statistics and the area of each attribute and the proportions over the two periods. table 2 shows that in 7319.64 km2 of zhengzhou area, the greatest proportion is grass land, 47.00% in 1988 and 37.59% in 2006. the urban areas and barren land have increased individually. the areas of crop land, grass land, forest, and water have been decreased. unfortunately, there are few conventional data sources for the study area available at the present time. the analyses were thus primarily based on information derived from the satellite data. the reasons for land use/cover change could be analyzed as follows: 1) rapid development in urbanization escorted the speedy growing economy in zhengzhou city. a great change in land use/cover has occurred in 1988-2006. uban areas and barren land increased by 246.65%, and 8.02%. on the other hand areas of grass, forest, crop land, and water shrinked by 20.02%, 11.52%, 7.09%, and 5.98% respectively through out the eighteen years (table 2). it indicates degradation of land quality. a major conclusion is the reduction in agricultural yield capacity. 2) cultivated land area declined from 3253.85 km2 in 1988 to 3244.2 km2 in 2006. the ratio between the crop land areas to barren land is 1.39 in 2006 whereas it was 1.03 in 1988. 3) the residential area increased from 295.10 km2 to 1021.59 km2. this occurred over the exploitation of cultivated land. 4) forest and grass land has significantly decreased whereas an enlargement in barren land took place. this imposes great disadvantages on soil conservation. 5) with the continuous increase in the population, the area of crop land has been decreased slightly but the grass land area has decreased significantly during the study period. these alterations might cause sandy desertification development in the area and the changes of regional groundwater resources. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ bassam f. al-bassam al-khwarizmi engineering journal, vol. 6, no. 2, pp 72-82 (2010) 80 6) barren land in loess tilted slope area (ii2) in the western part has been significantly changed to crop land. 7) the grassland and cropland area in the eastern part of the study area has changed significantly to barren land with the continuous increase of population and livestock during the 18-years period. fig.8. dynamic patterns of area change of land use/cover type in zhengzhou area. table 2. the statistics of classification outcome over the two periods in zhengzhou area. type area (km2) proportion (%) change (%) 1988 2006 1988 2006 water 85.51 80.18 1.17 1.10 -5.98 forest 241.52 214.07 3.30 2.92 -11.52 crop land 1776.04 1649.49 24.26 22.54 -7.09 urban area 295.10 1021.59 4.03 13.97 246.65 grass land 3437.81 2751.34 47.00 37.59 -20.02 barren land 1477.81 1594.71 20.19 21.81 8.02 7. conclusions and recommendations in the establishment of land use/cover classification, laminar extraction is the most reliable technique as it is based on the spectral characters of a typical attribute. the results show rapid enlargement in urban areas while crop fields are diminished. it reflects degradation in land quality and a decline in yield capacity could be inferred. noticeable changes in land use/cover have taken place over the years 1988-2006 (figure 8). urban areas and barren land increased by 246.65% and 8.02% while the decreased land types were forest, crop land, grass land, and water (11.52%, 7.09%, 20.02%, and 5.98% respectively). these changes were the result of physical and anthropogenic factors. as a result of land use/cover changes and human activities, an environmental degradation occurred in the whole this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ bassam f. al-bassam al-khwarizmi engineering journal, vol. 6, no. 2, pp 72-82 (2010) 81 area from 1988 to 2006, such as water changes and vegetation degeneracy. in the future land use planning and management, more attention is to be paid to the effect of land development on ecological environment. further studies concerned with the analysis of the assessment of related environmental impacts and socioeconomic consequences are suggested. additional census data would be useful. the concerned department in the republic of china should take the following steps to overcome land degeneration, such as: forbidding reclamation on steep slops; redirecting land farming into land forestry in addition to planning of forestry; controlling the water loss and soil erosion; and maintaining a balance on ecology and improve the grass coverage in karst regions. 8. references [1] albassam, b. f., 2007. dynamics of land use/cover change in puding city area using remotely sensed data. journal of china university of geosciences, vol. 18. special issue:165-167. 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[10] turner, b.l., and meyer, w.b., 1994. global land use and land cover change-an overview. in: meyer, w.b., and turner, b.l., editors, changes in land use and land cover: a global perspective, university of cambridge, cambridge 1994: 3–10. [11] turner, b. l., skole, d., sanderson, s., fisher, g., fresco, l., and leemans, r., 1995. land-use and land-cover change: science/research plan. 1gbp report no. 35, hdp report no. 7, international geosphere-biosphere programme, stockholm, sweeden. [12] vitousek, p. m., mooney, h. a., lubchenco, j., melillo, j. m., 1997. human domination of earth’s ecosystems. science 277: 494499. [13] wang qiao, yang yipeng, huang jiazhu, 2005. environmental remote sensing. science publishing company, beijing. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ )2010( 82-72 ، صفحة2، العدد 6مجلة الخوارزمي الھندسیة المجلد ان البسام مبسام فر 82 منطقة دراسةحالة ال :في الغطاء االرضي باستخدام بیانات التحسس النائيالتغیر تحلیل الصین, مقاطعة خنان, جینغ جو ان البساممبسام فر الجامعة المستنصریة/ كلیة الھندسة :الخالصة ي من التغیرالسریع في االقالیم الجافة وشبھ الجافة في الصینعانت ,في العقدین االخیرین كاني الغطاء االرض و الس بب النم ذاء بس ى الغ ة ال ة للحاج . نتیج نة دینامیكیة اتحلیل تم في ھذه الدراسة ن س و م غ ج نة 1988لتغیر في انواع الغطاء االرضي في منطقة جون ى س ام . 2006ال تخدام نظ م اس ة ت ذه العملی ي ھ ف ي اء االرض نیف الغط ائيبلتص س الن ات التحس یر بیان ى تفس اد عل ي . االعتم تخالص الطبق ة االس تعملت طریق laminar extraction) اس technique) اء ة الغط ة لنوعی زة النموذجی فات الممی د الص ي تحدی ریع لم . ف ادي الس ع التطوراالقتص ھ م ائج ان رت النت ة اظھ ادة نطق اك زی ان ھن و ف غ ج جون ح تدریجیة في المدن ونقصان ف كل واض اتي بش اء النب ي الغط دھور ف ة والت واع . ي الغطاء النباتي وھذا یعكس االنحطاط في نوعیة الیابس رت ان ان ائج اظھ النت كانیة وفة , (urban area)الغطاء االرضي التي ازدادت مساحتھا ھي المناطق الس ي المكش بة (barren land)واالراض ي %8.02و , %246.65 بنس ف ائش , (crop land)االراضي الزراعیة , (forest land)لغابات احین ان مساحات اة بالحش ي المغط اه , (grass land)واالراض د (water)والمی ق والي %5.98و %20.02,, %7.09, %11.52بنسبة انخفظت ى الت یط . عل ل التخط ن اج ده م ات مفی ة بمعلوم ة المحلی زود الحكوم ن ان ت ائج یمك ذه النت ھ .نوعیة الغطاء ودراسة تاثیره على البیئةادارة و المستقبلي this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ microsoft word production of protease enzyme from wheat straw al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 4, no. 2, pp 10 18 (2008) production of protease enzyme from wheat straw mohammed a. atiya biochem. eng. dept., al-khwarizmi coll.eng . baghdad university (received 9 september 2007; accepted 22 january 2008) abstract protease enzyme production was studied and optimized as a first step to collect information about solid state fermenter) to produce protease enzyme. a local isolated aspergillus niger was used for this study with constant spores feeding in every experiment at (105/g). experiments carried out in conical flasks with (250 ml) containing (10 g) of wheat straw as a substrate with different conditions included temperature, ph, hydration ratio, and fermentation time, the results comprised by measuring protease activity (u). the results showed that the best activity can be obtained at (t = 32°c, t= 100 hrs, ph= 2.5 and hydration ratio is 1:3). on the other hand the results is courage to proceed to design a solid state protease fermenter from wheat straw. keywords: fermentation, protease, straw, ph, hydration, solid state fermenter. introduction protease enzyme is one of the most important industrial products also it used in many food and pharmaceutical applications. it is used in 1.lether industries in dehairing and bating stages. 2.detergents manufacturing 3.cheese manufacturing 4.protein hydrolysates most organisms (i.e. bacteria fungus) produce protease. the important thing to industry is to obtain extracellular enzymes. there are different type (acidic and basic) of this enzyme depending on the organism and the cultivation conditions. the microps produce protease enzyme include type and six of bacteria and fungus differ in their microorganism, composition according to the products and the growing circumstances. such microps can be isolated from natural sources like soil, crops material food by planting them in a amid contain protein source and preparing the proper circumstances to grow the microps, usually the milk agar is used for this purpose. the primarily isolation may be done by making a farms of raw materials by adding cheep protein materials to soil the amending the ph to produce the demanded enzyme and keep them into convent temperature. there are more than one definition to the substrates of solid states fermentation, one of them it: growing of microps on solid state without presence of water, or its substrate in which growing and producing microps on solid state were found (michael, 1988, agosin, 1985, hameed, 1999, battaglino, 1991, cannel, 1980, chen, 1977). the aim of this research is to study the operating conditions of producing acidic protease enzyme from wheat straw by solid state fermentation to aspergillus niger and obtain the optimum conditions which can be used for future study of bioreactor design to produce this enzyme. materials and methods wheat straw used as a substrate for solid state fermentation hydrated by sodium acetate buffer, and a local isolated aspergillus niger was used as enzyme production source , sodium acetate, casein, tca(trichloroacetic acid) were used as a chemicals ,also the following equipments were used for measures and analysis; sensitive balance, ph meter, autoclave (sterilizer), incubator, centrifuge, oven (dryer), spectrophotometer (uv), pipette, micro-pipette, test tubes, conical flasks. mohammed a. atiya al-khwarizmi engineering journal, vol. 4, no. 2, pp 10-18 (2008) ١١ fermentation procedure the experiments were carried out in identical 250 ml conical flasks each containing 10 g of wheat straw substrate which was hydrated by adding 0.02 molar of sodium acetate buffer solution with a certain value of hydration ratio as mentioned in attached (tables, 2, 3 and 4). the flasks were closed with cotton wool plugs. the medium was sterilized by an autoclave operating at 121°c of temperature, and pressure of 1.5 bar for 15 minutes. proliferation was carried out by adding 1 ml inoculums to the medium and incubated at a certain temperature with respect to variables study as shown in tables (2, 3 and 4) and figures (1 to 8) later. incubation periods ranged between (28-156 hr.), ph (1-4.5), temperature (24-38°c), hydration ratio (1:1-5.5:1 wt/vol), size of inoclum (spore number) was constant 105/g wet weight. at the end of each of run, the samples from each flasks were prepare to the analytical step. analytical procedure enzyme activity protease activity was measured by degradation of casein. 2 ml of culture filtrate was added to 2 ml of 1% (w/v) casein (ph 7.5) and incubated for 10 min at 40°c. the reaction was stopped by adding a protein-precipitating agent, 4 ml of 0.4 molar trichloroacetic acid (tca). solutions were centrifuged in speed of 2500 rpm for 20 minutes. the precipitated protein was removed by filtration and the absorption of filtrate was measured at 275 nm. one unit of protease activity (u) was defined as the amount of enzyme that released 1 micro gram of tyrosine per min under assay condition (ph 7.5, 40°c). blank was prepared by the same way except adding tca before adding enzymes the values will compare with prepared standard absorption tyrosine curve at 275 nm (liy, 2002, murachi, 1976). protein concentration dissolving the precipitated protein which was removed as mentioned above by adding 0.05 molar naoh and the optical density of the solution was measured at 280 nanometer and 235 nanometer. blank solution of 0.05 molar naoh was used. the equation used to estimate protein concentration is (whiteaker,and granum 1980): protein concen.(mg/ ml) = (light abs. at 235 nm– light abs. at 280nm)/2.5 … (1) results and discussion effect of hydration ratio aspergillus niger was cultured or inoculate in hydrated wheat straw by adding 0.02 molar of sodium acetate buffer in the range of (1:1–5.5:1 wt/vol). the effect of hydration ratios were studied. these studies were conducted at constant temperature (32oc), ph = 2.5 and cultivation time of 100 hours as shown in table (1) and figs. (1, 2). table 1 hydration ratio effect on enzyme activity and enzyme yield at constant temperature of 32°c, incubation period of 100 hours and ph = 2. hydration ratio enzyme activity (×100) enzyme yield (×1000) (weight/ volume) (u /g protein) (u/g substrate) 1.00 6.30 0.48 1.50 10.00 0.60 2.50 11.90 0.70 3.00 12.40 0.79 3.50 11.50 0.75 4.50 7.70 0.50 5.50 2.80 0.30 from these results, the enzyme activity increased slightly with hydration ratio up to 1:3 and then decreases. the results indicated that at 1:3 hydrations ratio enzymes production with highest yield and activity of 790 units per g substrate and 1240 unit per mg protein respectively. the effect of hydration ratio can be divided in two partitions. in the first partition the increasing of hydration will increase mass transfer media needed for oxygen transformation and cetric acid produced dilution. but when hydration ratios more than (1:3) the concentration of nutrients will be decreased rapidly and that inhibit the yeast growth and also enzyme quality and quantity will be that decrease the activity of protease enzyme. effect of ph different values of ph medium were studied at constant temperature (32°c), proliferation time of 100 hours and hydration ratio of 1:3 ,as shown in table (2) and figures (3 and 4). the studied of ph values of growth medium were initially adjusted to ph values of 1, 2, 2.5, 3, 3.5, 4, 4.5 before sterilization. mohammed a. atiya al-khwarizmi engineering journal, vol. 4, no. 2, pp 10-18 (2008) ١٢ table 2 ph values effect on enzyme activity and enzyme yield at constant other variables (temp. =32°c, incubation period of 100 hours and hydration ratio 1:3. ph enzyme activity (×100), enzyme yield (×1000) u /g protein u/g substrate 1 8.8 0.41 2 9.2 0.46 2.5 9.8 0.58 3 9 0.48 3.5 7.3 0.39 4 5.9 0.32 4.5 4.4 0.242 the results showed that the activity of enzyme increases from (880 u per g protein to 980 u per g protein) when the ph increases from 1-2.5 respectively and then decreases to reach 440 u per g protein when the ph is 4.5. also the results showed that the enzyme yield has the same behavior and reach the maximum value of 580 u per g substrate when ph value is 2.5 .the results indicated the best proliferation ph value of 2.5. effect of temperature the effect of different temperature range between (24 to 38°c) were studied at constant ph 2.5, proliferation time of 100 hours and hydration of 1:3 as shown in table (3) and figs. (5 and 6). the enzyme activity increased from (1020 to 1200 u per g protein) when temperature increased from 24 to 32oc and then decreased from this value to (620 u per g protein) when temperature reached 38oc.the reason of this behavior can be consider as the relation between organism growth and temperature in one hand and the relation between organism growth and enzyme production in the another hand. aspergillus niger can be grown well in middle temperature range around 32oc. table 3 effect incubation temperature on enzyme activity and enzyme yield at constant ph =2.5, incubation period of 100 hours and hydration ratio 1:3. temp.( oc) enzyme activity (×100), enzyme yield (×1000) u /g protein u/g substrate 24 10.2 0.6 28 11.5 0.68 32 12 0.7 34 10.4 0.64 36 8.5 0.49 38 6.2 0.28 effect of cultivation time proliferation of aspergillus niger for several incubation time were studied at constant temperature (32°c), ph 2.5 and hydration ratio of 1:3 in order to produce highest enzyme activity with highest yield .the results indicated that when proliferation time increases that will cause an increase in enzyme activity and yield from 180 and 130 to reached its maximum values of 1200 and 780 respectively at time equal to 100 hours during increasing in cultivation time from 28 to 100 hours and then decreases to 700 and 600 at time equal to 156 hours .the results indicated the highest yield enzyme activity and highest enzyme activity obtained at incubation period of 156 hours as shown in table (4) and figures (7 and 8). table 4. effect of incubation time on enzyme activity and enzyme yield at constant other variables (temperature of 32°c, ph of 2.5 and hydration ratio of 1:3. time (hours) enzyme activity (×100), enzyme yield (×1000) u /g protein u/g substrate 28 1.8 0.13 52 6.2 0.3 76 11.3 0.6 100 12 0.78 124 11.1 0.74 148 9 0.68 156 7 0.6 conclusion from this study it can be recommended that it is good to produce protease enzyme with high activity using wheat straw substrate plants as a solid state fermentation of aspergillus niger. so it is important to go ahead in studying other parameters such as hydrodynamic of bioreactor to produce this enzyme according to the parameters mentioned in this study. the results showed that the best activity can be obtained at (t=32°c, t=100 hrs, ph= 2.5 and hydration ratio is 1:3). mohammed a. atiya al-khwarizmi engineering journal, vol. 4, no. 2, pp 10-18 (2008) ١٣ fig.1 hydration ratio effect on enyzme activity at constant temperature of 32 ,incubation time of 100 hours and ph of 2.5. 0 2 4 6 8 10 12 14 0 1 2 3 4 5 6 hydration ratio(weight /volume) e n z y m e a ct iv it y (* 1 0 0 ), u / g m p ro te in fig.2 hydration ratio effect on enzyme yield at constant temperature of 32 ,incubation time of 100 hours and ph of 2.5. 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0 1 2 3 4 5 6 hydration ratio(weight /volume) e n zy m e y ie ld ( * 1 0 0 0 )u /g m s u b st ra te mohammed a. atiya al-khwarizmi engineering journal, vol. 4, no. 2, pp 10-18 (2008) ١٤ fig .3 ph values effect on enzyme activity at constant other variables (temperature of 32 ,incubation time of 100 hours and hydration ratio of 1:3. 0 2 4 6 8 10 12 14 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 ph values e n zy m e a ct iv it y (* 1 0 0 ), u / g m p ro te in fig 4.ph values effect on enzyme yield at constant other variables (temperature of 32 ,incubation time of 100 hours and hydration ratio of 1:3. 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 ph values e n zy m e y ie ld ( * 1 0 0 0 )u /g m s u b st ra te mohammed a. atiya al-khwarizmi engineering journal, vol. 4, no. 2, pp 10-18 (2008) ١٥ fig. 5 effect of incubation temperature on enzyme activity at constant ph 2.5 , incubation time of 100 hours and hydration ratio of 1:3 . 0 2 4 6 8 10 12 14 22 24 26 28 30 32 34 36 38 40 temperature.(c) e n zy m e a ct iv it y (* 1 0 0 ), u / g m p ro te in fig. 6 effect of incubation temperature on enzyme yield at constant ph 2.5 , incubation time of 100 hours and hydration ratio of 1:3 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 20 22 24 26 28 30 32 34 36 38 40 temperature.(c) e n zy m e y ie ld ( * 1 0 0 0 )u /g m s u b st ra te mohammed a. atiya al-khwarizmi engineering journal, vol. 4, no. 2, pp 10-18 (2008) ١٦ fig.7 effect of incubation time on enzyme activity at constant other variables (temperature of 32 ,ph of 2.5 and hydration ratio of 1:3) 0 2 4 6 8 10 12 14 0 20 40 60 80 100 120 140 160 180 time(hours) e n zy m e a ct iv it y (* 1 0 0 ), u / g m p ro te in fig.8 effect of incubation time on enzyme yield at constant other variables (temperature of 32 ,ph of 2.5 and hydration ratio of 1:3. 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0 20 40 60 80 100 120 140 160 180 time(hours) e n zy m e y ie ld ( * 1 0 0 0 )u /g m s u b st ra te mohammed a. atiya al-khwarizmi engineering journal, vol. 4, no. 2, pp 10-18 (2008) ١٧ reference [1] agosin, e., solid state fermentation, 1985. [2] battaglino, r. a., culture requirements of production of protease by aspergillus orzyea in solid state fermentation. appl. microbial. biotechnol. 35:292 , 1991. [3] cannel, e., and moo-young, m., solid state fermentation systems, 1980. [4] cohen , b. l., ,the proteases of aspergillus. in genetic and physiology of aspergillus, p 281, 1977. [5] hameed, a.; keshavarz, t.; evans, c. s. effect of dissolved oxygen tension and ph on the production of extracellular protease from a new isolate of bacillus subtilis k2, for use in leather processing. j. chem. technol. biotechnol., 74, 1999. [6] liy,h, hu, h. kinetic model of neutral proteins fermentation process. j. chem. eng. chin. univ. 9, 404-408, 1995. [7] murachi, t, methods in enzymology, vol.19, p.273, 1976. [8] whiteaker, j.r. and granum, p.e., an absolute method of protein determination, annl. biochem, 1980. [9] michael j. pelczar , microbology ,1988. mohammed a. atiya al-khwarizmi engineering journal, vol. 4, no. 2, pp 10-18 (2008) ١٨ انزيم البروتيز من نخالة الحنطة انتاج محمد عبد عطية جامعة بغداد / كلية هندسة الخوارزمي / قسم هندسة الكيمياء االحيائية الخالصة المخم"ر غ"رض تص"ميملتم دراسة عملية إنتاج انزيم البروتيز كخطوة اولى من أجل وضع المعايير االساسية وإيجاد الظروف التش"غيلية fermenter من خالل تنمية كائنات حية مجهرية وهي نوع من االعفان تسمى في الحالة الصلبةaspergills niger)،( عي هو على وسط زر تعادل"ة بنس"ب منخالة الحنطة . تتكون مراحل البحث من تغيير الحامضية للوسط الزرعي حيث نقوم بترطيبه بمحاليل قاعدية وحامضية واخ"رى لمع"د س"لفا" امل حيث يوضع بها الوسط الزرعي وهو نخالة الحنطة وي"تم اللق"اح بالك"ائن الح"ي ٢٥٠مختلفة حيث توضع باوعية حجم ترطيب رارة عل"ى الفعالي"ة / غرام ثم يتم اخذ النماذج ودراسة تاثير الحامضية ونسبة الترطي"ب،زمن التخمي"ر، ودرج"ة الح" ٥١٠بعدد من الخاليا عددها لمتغيرات.الالنزيم المنتج وكميته حيث يتم تثبيت احدى المتغيرات السابقة وتثبيت المتغيرات االخرى وايجاد الظروف المثلى لهذه ، اعةس"" ١٠٠م، وال""زمن يس""اوي °٣٢المخم""ر ه""ي درج""ة الح""رارة تس""اوي تش""غيلية المثل""ى لغ""رض تص""ميم أظه""رت النت""ائج إن الظ""روف ال .١:٣لترطيب تساوي ونسبة ا ٢٬٥والحامضية تساوي this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 18, no. 4, december, (2022) p. p. 113 comparative study between activated carbon and charcoal for the development of latent fingerprints on nonporous surfaces hadeel faroak hameed* alaa k. mohammed** dheaa s. zageer*** *,**department of biochemical engineering / al-khwarizmi college of engineering/ university of baghdad/ iraq ***forensic dna center for research and trainingcollege of science/ university of al-nahrain/ iraq hadeel.farook1205a@kecbu.uobaghdad.edu.iq: email* **email: dr.alaa@kecbu.uobaghdad.edu.iq **email: dheaairoai72@gmail.com (2022 september 7 2022; accepted uly j 20received ) https://doi.org/10.22153/kej.2022.09.001 abstract for criminal investigations, fingerprints remain the most reliable form of personal identification despite developments in other fields like dna profiling. the objective of this work is to compare the performance of both commercial charcoal and activated carbon powder derived from the alhagi plant to reveal latent fingerprints from different non-porous surfaces (cardboard, plain glass, aluminum foil sheet, china dish, plastic, and switch). the effect of three variables on activated carbon production was investigated. these variables were the impregnation ratio (the weight ratio of koh: dried raw material), the activation temperature, and the activation time. the effect factors were investigated using central composite design (ccd) software. the optimum activation conditions were found as an impregnation ratio of 1:2.6, activated time of 160 min, and temperature of 630oc. the results of the comparison show that alhagi active carbon powder (aac) has a high ability to develop latent fingerprints on all surfaces except on plastic surfaces while the commercial charcoal failed to develop the latent fingerprint on both plastic and aluminum foil sheets surfaces. aac was found to clearly show every feature of the latent fingerprints more than commercial charcoal for both males and females. also, aac has the ability to show latent fingerprints till 15 days while commercial charcoal has the ability to show latent fingerprints just till 7 days. keywords: fingerprint, non-porous surface, personal identification, ccd. 1. introduction a fingerprint is an impression of the friction ridges found on the palmer side of the finger, often used for biometric identification in criminal investigations [1]. before a baby is born, its fingerprint is already well developed in its mother's womb and unique fingerprints started to form [2]. friction ridges are formed when a baby's environment is formed and the effect of pressure on its fingers as a result of the baby's touching [3]. on everyone's fingers and toes, there are faint lines that can be seen called friction ridges [4]. in criminal cases, this identity represents important physical evidence. because every human being has a unique fingerprint pattern, these fingerprints provide almost perfect verification of the presence of a person at the crime scene [5]. due to their dissimilar ridges and patterns, these fingerprints may easily be recognized. water, amino acids, fatty acids, and minerals constitute fingermarks, which can be described as imprints of regions left on a friction ridge skin surface using various analytical methods [6]. for the development of latent fingerprints on diverse surfaces, several powders have been used. mailto:*ali.abbar@kecbu.uobaghdad.edu.iq mailto:*ali.abbar@kecbu.uobaghdad.edu.iq mailto:dheaairoai72@gmail.com https://doi.org/10.22153/kej.2022.09.001 hadeel faroak hameed al-khwarizmi engineering journal, vol. 18, no. 4, p.p. 113 (2022) 2 some fingerprint powders are dangerous and can lead to major health issues so it's important to find a greener option that is just as effective at detecting latent fingerprints on dry, non-porous surfaces [7]. as a result, various attempts have been made to create powders that are easily accessible, nontoxic, and inexpensive for developing latent fingerprints. powdering is a technique that involves applying powder particles to natural residues deposited on a latent fingerprint. friction between powder particles and natural residues causes adhesion [8]. for a long time, natural carbon elements including charcoal and active carbon have been a major component in traditional fingerprint formulations (mostly in grey and black powder)[9]. charcoal is a lightweight black carbon residue produced by strongly heating wood (or other animals and plant material) to remove all water and volatile constituents[10]. charcoal has been used since the earliest times for a large range of purposes due to its high surface including as a powder for the development of latent fingerprints [11] . activated carbons are widely used in numerous fields, such as water treatment processes, environmental protection, catalyst support, protection from toxic substances, solvent recovery, decolorizing, biomedical engineering and metal recovery [12]. this study represents two samples of powders commercial charcoal and active carbon prepared from the alhagi plant (aac) to develop latent fingerprints by these powders on non-porous surfaces such as (cardboard, plain glass, aluminum foil sheet, china dish, plastic, and switch). the purpose of the current work is to compare which powder gives good and better results to develop latent fingerprints. another purpose is to determine the characteristics of alhagi activated carbon under different influential factors such as impregnation ratio, activation temperature, and activation time furthermore, a comparative study was implemented including both males and females on the same surface (cardboard). the time for the latent fingerprint to remain on the surfaces is also diagnosed. 2. materials and methods 2.1 materials alhagi plant was collected from some areas in baghdad. potassium hydroxide (koh) was provided from (himedia, india) as a chemical activation agent. nitrogen was used as an inert gas in the carbonization step to prevent raw materials combustion. all the chemical reagents used in this study were analytical grade and were not purified further. the commercial charcoal was provided by the acura brand (india). 2.2 preparation activated carbon the alhagi plant was cut into small pieces and washed well with distilled water to remove any dirt from its surface. after then dried at 60 oc for 24 h and crushed to the required size (2 mm). the dried mass of alhagi pieces was mixed and kneaded with potassium hydroxide solution. using varying impregnation ratios and left overnight at room temperature. then, the sample was filtered from the base residue, washed with distilled water several times, and dried at 100 oc for 2 h. the dried material was put in a steel box in the furnace under a purified nitrogen flow of 120 cm3/min. after that, the sample is cooled to room temperature under the same nitrogen flow. the carbon powder was washed with hot distilled water at 60 oc until the ph value of the leachate become (6-7) to eliminate the residual base. the carbon powder produced from the carbonization step was dried at 60oc for 24 h, pulverized, sieved to 44 microns (325-mesh screen), and put into a small container with a tight cover to prevent moisture from contacting the powder[13]. 2.3 sample characterization a serval of characterization steps was carried out to find the best operating conditions for preparing activated carbon from the alhagi plant using koh solution as the activating agent. scanning electron microscope (sem) was used to investigate the surface shape and its topographical properties. the obtained images are threedimensional which represent the surface shape accurately. analysis of the elements that compose the precursors was carried out with an energy dispersive x-ray spectrophotometer (eds). semeds analysis was carried out by tescan, vega iii electron microscope (czech republic). fourier transform infrared spectroscopy (ftir, ir affinity-1 shimadzu, japan) was employed to determine the functional groups that exist in the composition of both the alhagi plant and alhagi activated carbon. hadeel faroak hameed al-khwarizmi engineering journal, vol. 18, no. 4, p.p. 113 (2022) 3 2.4 design of experiments one of the research objectives is to produce activated carbon from alhagi and find the optimum production conditions. generally, many factors affect the production of aac by chemical activation, such as activation time, activation temperature, and impregnation ratio ir. the effects of these factors on the response (yield of aac) were investigated using central composite design (ccd). their ranges were chosen to be 500-800 ºc for the activation temperature, 1:1-1: 3 for the impregnation ratio, and the range of the activation time was chosen to be 1-4 h. [14]. central composite design (ccd) software is a commonly used statistical approach for optimizing processing parameters and determining regression model equations from the experimental results. it can also be used to investigate the interactions between the various parameters influencing the process response[15]. for the purpose of the experimental design, a significance level (denoted as α or alpha) of 0.05 value is always satisfied to be selected. if the pvalue is less than 0.05 the parameter is statistically having a significant effect on the response. in contrast, if the p-value is higher than 0.05, there is no statistically significant association between the variables and the response[16]. the f-test, which is the ratio of the mean of the square of regression to the mean of the square of residuals, can be used to determine the significance of the model equation by comparing the f-test value to the tabulated f-values while taking into consideration the degrees of freedom associated with the regression and residual variances. the mathematical model is said to be well fitted to the experimental data if the calculated f-value is higher than the tabulated f-value. in addition, the high f-value of the studied parameters indicates that this parameter is significant[17]. the polynomial equation linking the response with the independent variables is suggested by software given in eq. (1) 𝑓(𝑥) = 𝑎0 + ∑ 𝑏𝑖𝑥𝑖 𝑁 𝑖=1 + ∑ 𝑐𝑖𝑖𝑥2𝑖 𝑁 𝑖=1 + ∑ 𝑐𝑖𝑗𝑥𝑖𝑥𝑗 𝑁 𝑖𝑗(𝑖<𝑗) + ∑ 𝑑𝑖𝑥3𝑖 + ∑ 𝑒𝑖𝑥4𝑖 … (1) 𝑁 𝑖=1 𝑁 𝑖=1 where 𝑁 is the number of model inputs, 𝑓(𝑥)is the response, 𝑥𝑖 is the set off model inputs, 𝑎0 is the constant coefficients, 𝑏𝑖 and 𝑐𝑖𝑖, are model coefficient, 𝑐𝑖𝑗 interactions coefficient, and 𝑖 and 𝑗 are 1,2,3. 3. results and discussion 3.1 characterization of activated carbon 3.1.1 scanning electron microscopy (sem) the scanning electron microscopy technique was carried out to observe the morphology of the surface of the precursor, alhagi powder, and the prepared alhagi activated carbon (aac). figure1b shows that the surface nature of (aac) is porous and loose. as a result of activation, they have a large number of pores, are full of cavities, and are quite irregular. the reaction between carbon atoms and koh, as well as the impact of high temperature on the activation process, result in different pore shapes as shown in figure (1) fig. 1. sem images of (a) alhagi powder (b) alhagi activated carbon (aac). b a hadeel faroak hameed al-khwarizmi engineering journal, vol. 18, no. 4, p.p. 113 (2022) 4 elemental compositions of raw material (alhagi) and aac were investigated by energy dispersive spectroscope (eds). the results are shown in figures (2) and (3) respectively. it is clear from these figures that the carbon percentage for active carbon produced from raw alhagi plants is raised from 57.38% to 97.76%. whereas all elements’ compositions are reduced due to the carbonization process or evaporation. fig. 2. eds analysis of alhagi. fig. 3. eds analysis of aac. 3.1.2 the ft-ir analysis of alhagi powder and aac figure (4) shows ftir spectra for both alhagi powder (alh) and alhagi activated carbon (aac). the broad peak that appears around 3298.28 cm-1 in (alh) is assigned to the hydroxyl group; this indicates the presence of moisture that disappears from (aac) spectra due to its elimination by the activation process. the band at 2916.37 cm-1 in (alh) is ascribed to alkane (c-h) stretching vibration, the fading of this peak from (alh) spectra indicates hydrogen removal during the activation process. the bands at 1612.49 cm-1 and 1411.89 cm-1 that appeared in (alh) and (aac) spectra respectively are due to the skeletal c = c vibrations of organics. the peaks of 667.37 cm-1 and 709.80 cm-1 in the spectra of alhagi and ac respectively are assigned to the bending vibration of carbon bonds (c≡c). the band at 1099.43 cm−1 in (alh) has been assigned to (-co-c) stretching. the bands at 1141.86 cm−1 in (aac) have been assigned to (c–o) stretching and the bands at 1018.41 and 871.82 have been assigned to(c-h plane) and (c-h bend) stretching [18], [19]. hadeel faroak hameed al-khwarizmi engineering journal, vol. 18, no. 4, p.p. 113 (2022) 5 fig. 4. ftir spectra of alhagi plant (alh) and alhagi activated carbon (aac). 3.2 yield of activated carbons. the preparation conditions and results of alhagi activated carbon are shown in table (1). the values of the parameters in the table were selected according to the ccd program, while the yield was experimentally evaluated. the sample with an ir of 1:3, activation temperature of 650 oc, and 150-min activation time show a maximum yield of 86.14 %. table 1, the predicted values of yield using ccd software. 3.3 interactive effect of the impregnation ratio and activation time the effect of the impregnation ratio and time interaction is demonstrated in figure (5). the curves show that the yield of activated carbon tends to increase as the impregnation ratio rises till it reaches a value of about 2.6. pore formation is influenced by the impregnation ratio. the intercalation of potassium metal into the carbon structure promotes pore formation. thus, high impregnation ratio increases the amount of potassium metal that can be intercalated and promotes more pore formations. this results in an increase in the surface area and yield. on the other hand, the effect of the time parameter is clear. it can be seen from the contour curves that with the increase of the activation time, the yield increases gradually at the beginning and reaches optimum at an activation time of 2.66 h. increasing the yield runs ir: a time: b temp: c yield: r 1 2 2.5 650 80% 2 2.5 1.75 725 80.24% 3 2.5 1.75 575 79% 4 2 1 650 68.04% 5 1.5 3.25 725 54.66% 6 3 2.5 650 86.14% 7 2 4 650 74.36% 8 2.5 3.25 575 85% runs ir: a time: b temp: c yield:r 9 1.5 1.75 725 62.3% 10 1.5 3.25 575 75.56% 11 1.5 1.75 575 64.44% 12 2 2.5 650 82.42% 13 2 2.5 500 71% 14 2 2.5 800 58.6% 15 1 2.5 650 52.46% 16 2.5 3.25 725 73.63% hadeel faroak hameed al-khwarizmi engineering journal, vol. 18, no. 4, p.p. 113 (2022) 6 with the activation time is due to more carbon atoms at active sites reacting with the activation agent and forming a new pore structure and the activating reaction reaches a full stage. then, the curve begins to take a stable shape because carbon atoms on the carbon skeleton are consumed and original micropores develop into micropores, r es u l t i n g i n a d ec r ea s e i n y i e l d . t h is is consistent with the finding of li et al., (2017) [20] who examined the influence of the same experimental parameters on the yield of activated carbon produced from gulfweed. so, theoretically, the optimized values of impregnation ratio and activation time obtained using ccd software are 2 .6 and 2 .66 h (160 min) r esp ec t ively . fig. 5. the interaction between the impregnation ratio and time (a) contour (b) 3d surface. 3.4 interactive effect of the impregnation ratio and activation temperature the interactive effect of the impregnation ratio and activation temperature is shown in figure (6). from the contour plot in figure (6), we notice that the optimum value of temperature is 630oc and the impregnation ratio is 2.6. regarding the activation temperatures, it was perceived that as the temperature was increased from 500 to 620 °c, the yield of aac increased till it reached an optimum value at nearly 630 oc. these results interpreted that as the activation temperature increased, the structure tended to become more porous due to koh evaporation. after that, the percentage of yield starts to go lower because high activation temperatures caused pore explosion, resulting in reduced yield values [21]. a b hadeel faroak hameed al-khwarizmi engineering journal, vol. 18, no. 4, p.p. 113 (2022) 7 fig. 6. the interaction between the impregnation ratio and temperature a) contour b) 3d surface. 3.5 analysis of variance (anova) statistical significance of the factors was established with analysis of variance (anova). impregnation ratio ir has been encoded as(a), time of activation (b), temperature (c ( and the yield (r). the experimental values obtained from the lab experiments were compared with the predicted results calculated by statistical design software. the value of coefficient r2 is equal to 0.9696, indicating that the experimental data fits perfectly with the quadratic model. figure (7) plots the predicted values versus experimental values, which is a good tool for studying the significance of the suggested model. as can be seen from the plot, all the data points are close to the line, indicating that the experimentally observed data fits well with the empirical model. the model equation for yield (r%) is shown mathematically in eq. (2) in terms of coded factors. the terms express the relationship between the independent variables and the dependent response of the system. 𝑅%=81.32 + 8.02𝐴 + 0.97𝐵 − 3.62𝐶 − 0.5100𝐴𝐵 +1.61𝐴𝐶 − 3.92𝐵𝐶 −2.98𝐴2 − 2.50 𝐵2 − 4.10 𝐶2 …(2) fig. 7. the predicted values versus experimental values. a b hadeel faroak hameed al-khwarizmi engineering journal, vol. 18, no. 4, p.p. 113 (2022) 8 from table (2) according to the lower p-value and a higher f-value, the most significant parameter is the impregnation ratio and activation temperature with the weak effect of time. it was also noted that the more effective interaction is between the temperature and time. table 2, anova for quadratic model source sum of squares df mean square f-value p-value model 1687.46 9 187.50 54.11 < 0.0001 significant a-ir 1028.48 1 1028.48 296.79 < 0.0001 b-time 15.05 1 15.05 4.34 0.0822 c-temp 209.96 1 209.96 60.59 0.0002 ab 2.08 1 2.08 0.6005 0.4678 ac 20.87 1 20.87 6.02 0.0495 bc 122.93 1 122.93 35.47 0.0010 a² 141.85 1 141.85 40.93 0.0007 b² 100.20 1 100.20 28.91 0.0017 c² 269.29 1 269.29 77.71 0.0001 residual 20.79 6 3.47 lack of fit 17.86 5 3.57 1.22 0.5932 not significant pure error 2.93 1 2.93 cor total 1708.25 15 3.6 comparison between charcoal and alhagi activated carbon (aac)on different surfaces the commercial charcoal and alhagi activated carbon (aac) were used for developing latent fingerprints on several nonpours surfaces that can commonly be found at the crime scene (cardboard, plain glass, aluminum foil sheet, china dish, plastic and switch.). the results show that the prepared aac has a high ability to develop the latent fingerprints on all surfaces except on plastic while the commercial charcoal failed to develop the latent fingerprint on both plastic and aluminum foil sheet surfaces. this is due to the adhesion property of the aac being greater than the charcoal, as a result of the activation and carbonation processes, which led to the development of the adhesion of the powder to the finger residue as shown in figure (8). hadeel faroak hameed al-khwarizmi engineering journal, vol. 18, no. 4, p.p. 113 (2022) 9 fig. 8. comparative visualizations of latent fingerprints between commercial charcoal and aac on several nonporous surfaces(a) cardboard. (b) plain glass (c) aluminum foil sheet. (d) china dish. (e) plastic(f) switch. 3.7 comparison between charcoal and alhagi activated carbon for both male and female the commercial charcoal and alhagi activated carbon (aac) were used to show their performance to develop latent fingerprints from ten volunteers for both males and females on the same surface (cardboard). the result of the comparison was shown in figure (9). it was noticed that aac gave clear prints and showed clearly all the minutiae of the latent fingerprints more than charcoal. c charcoal activated carbon (aac) d a a activated carbon (aac) charcoal e f d b e c f b hadeel faroak hameed al-khwarizmi engineering journal, vol. 18, no. 4, p.p. 113 (2022) 10 fig. 9. comparative visualization of latent fingerprints between commercial charcoal and aac powders(a) prepared powder (aac) for males. (b) prepared powder (aac) for females. (c) commercial charcoal for males. (d) commercial charcoal for females. 3.8 fingerprints lifespan the time for the latent fingerprint to remain on the surfaces was also diagnosed. nonporous surface(cardboard) was selected for this purpose and all samples were taken from the same volunteer at the same lab conditions. the fingerprints were developed after 1,4,7,15, and 25 days. figure (10) shows that the latent fingerprints present on the surface examined using aac can be successfully developed even for long time of stay on the surface, but the quality is decreased as the print’s lifespan increased. as shown in figure (10), clear visible fingerprint was noticed till 15 days, but less contrast was noticed after 25 days. while the performance of commercial charcoal to show the latent fingerprint is lower where visible fingerprint was noticed till 7 days only. fig. 10. comparative visualizations of latent fingerprints for both powders on the nonporous surface(cardboard) at different lifespans. (a) after 1 day. (b) after 4 days. (c) after 7 days. (d) after 15 days. (e) after 25 days. male a b c d fem ale a b c d e a b c d e aac commercial charcoal hadeel faroak hameed al-khwarizmi engineering journal, vol. 18, no. 4, p.p. 113 (2022) 11 4. conclusion the alhagi active carbon powder (aac) derived from the alhagi plant and commercial charcoal used to reveal latent fingerprints from different non-porous substrates. the (aac) powder was compared with commercial charcoal and tested for several surfaces (cardboard, plain glass, aluminum foil sheet, china dish, plastic and switch). three parameters were examined that affect the production of aac by chemical activation, such as activation time, activation temperature, and impregnation ratio ir. the yield of the produced activated carbon was chosen as a response. the effects of the experimental parameters were investigated using central composite design (ccd) software. the optimum values of variables for alhagi activated carbon were 1:2.6 as impregnation ratio, activation temperature of 630oc and activation time of 160 min which give the highest yield of 86.14%. the value of coefficient r2 is equal to 0.9696, indicating that the experimental data fits perfectly with the quadratic model. the final product was characterized by sem, edx and ftir, analysis. the prepared aac has a high ability to develop the latent fingerprints on all surfaces except on plastic while the commercial charcoal failed to develop the latent fingerprint on both plastic and aluminum foil sheet surfaces. in addition, it was noticed the prepared powder (aac) show clearly all the minutiae of the latent fingerprints and gives good results in developing latent fingerprints for both males and females. also, the time for the latent fingerprint to remain on the surfaces was diagnosed using two powders to visualization. it was found the prepared powder (aac) has the ability to clearly develop the latent fingerprints until 15 days while the performance of commercial charcoal to show the latent fingerprint is lower where visible fingerprint was noticed till 7 days only. acknowledgement we wish to thank the staff of the biochemical engineering department at al-khwarizmi college of engineering / university of baghdad for the continued support they have given me throughout my m.sc. studies. also, we appreciate all the efforts introduced by the criminal evidence investigation directorate for the co-operation and assistance through this work. 5. references [1] v. chauhan, “xournals fingerprint studies and dactyloscopy abstract : xournals,” vol. 03, no. 01, 2020. 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(2022) 1-13، صفحة 4العدد، 18الخوارزمي الهندسية المجلدمجلة هديل فاروق حميد 13 ةالجنائي االدلةتحضير وتشخيص مسحوق للكشف عن البصمة الوراثية الكامنة لتطبيقات **عالء كريم محمد هديل فاروق حميد* زغير*** خضياء شام الكيميائية االحيائية/ كلية الهندسة الخوارزمي/ جامعة بغداد*،**قسم الهندسة هرينالن ة***كلية العلوم/ مركز الدنا العدلي/ جامع hadeel.farook1205a@kecbu.uobaghdad.edu.iq :البريد االلكتروني* dr.alaa@kecbu.uobaghdad.edu.iqالبريد االلكتروني: ** dheaairoai72@gmail.comالبريد االلكتروني *** الخالصة save translation .dnaتظل بصبببما ابعبببابل كي الكبببكل ابكةر مودوقية لتقديد الهوية لن الرطم من التمورا أي مجاال ر مةل الجنائية،بالنسببببة للتقاياا ورق ماو , و الكاربون المنكط المقضر من نبا العاكول لن دة سموح طير مسامية ) التجاري مسقوق الجاركول اداءالهدف من الدراسة كي ماارنة وكيدسث وامل لن انتاج الكاربون النكبط ت ديرتم دراسبة ( . فتاح اضباءة,م سبم بسسبتيكي, المنكب عبقن عبيني ,سبم االلمنيوم قمعة من الزجاج , central composite designتقليل النتائج بمرياة التفعيل. تم التفعيل وزمن القرارة ودرجة المادة(كيدروكسيد البوتاسيوم / وزن )وزن التفعيلنسبة (ccd) للكاربون بينت النتائج ان . درجة سليزية 630 حرارة التفعيلدرجة و دقياة 160زمن التفعيل و 1: 2.6. وجد الظروف المةلن ند نسبة الغمر التجاري الجاركولمسببقوق أكببل م البسسببتيكي بينماالمقضببر من نبا العاكول لا الاابلية لن ااهار البصببما المخفية لن كل السببموح دا السبب النكببط كببببط يظهر كاأة موب البصببببمة المخفية لكس نكما ان لمسببببقوق الكاربون الم االلمنيوم. وسببببم البصببببما الكامنة لن كل من السببببم البسسببببتيكي بإاهار لمسبقوق الكاربون المنكبط قابلية لن ااهار البصبما الكامنة لفترا زمنية تصبل الن التجاري.من مسبقوق الجاركول أضبل واالناث( )للذكورالجنسبيين يام أاط. 7وعلت الن التجاري بالنسبة لمسقوق الجاركولالمخفية يوم بينما قابلية ااهار البصما 15 mailto:hadeel.farook1205a@kecbu.uobaghdad.edu.iq*البريد mailto:hadeel.farook1205a@kecbu.uobaghdad.edu.iq*البريد mailto:dr.alaa@kecbu.uobaghdad.edu.iq mailto:dheaairoai72@gmail.com this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 18, no. 4, december, (2022) p. p. 3244 ber performance improvement of dual chaotic maps based on stbc communication system lwaa faisal abdulameer * u. sripati** muralidhar kulkarni*** *department of information and communication/ al-khwarizmi college of engineering/ university of baghdad/ iraq **,***electronics and communication engineering department/ nitk. mangalore/ india *email: lwaa@kecbu.uobaghdad.edu.iq sripati_achary@yahoo.co.in :email** mkuldc@gmail.comemail: *** (2022 october 4 2022; accepted may 15 received) https://doi.org/10.22153/kej.2022.10.001 abstract sensitive information of any multimedia must be encrypted before transmission. the dual chaotic algorithm is a good option to encrypt sensitive information by using different parameters and different initial conditions for two chaotic maps. a dual chaotic framework creates a complex chaotic trajectory to prevent the illegal use of information from eavesdroppers. limited precisions of a single chaotic map cause a degradation in the dynamical behavior of the communication system. to overcome this degradation issue in, a novel form of dual chaos map algorithm is analyzed. to maintain the stability of the dynamical system, the lyapunov exponent (le) is determined for the single and dual maps. in this paper, the le of the single and dual maps have been computed numerically. increasing the dynamical behavior of the system by using more complex chaotic maps leads to inferiority in the overall system performance. so, in this work, the ber performance for the dual and single chaotic maps by exploiting the benefits of a hybrid chaos shift keyingmultiple-input-multiple-output (csk-mimo) communication system has been investigated. the results show that the dual tent map has more randomness, whereas the single logistic map has the least randomness. as well as the csk-mimo gives an outstanding ber performance when it compared with the siso system which helps in reducing the system’s inferiority. keywords: chaotic technique, dual, lyapunov exponent, stbc. 1. introduction a chaotic waveform is characterized as being deterministic, non-periodic, and very sensitive to any change in initial conditions, i.e., initializing the system with a slight difference in initial conditions generates a new sequence completely different from the original signal [1]. so, to encrypt sensitive data, a chaotic technique can be utilized to produce a key stream with high randomness. in any case, a single chaotic map is attackable to be descended by chaotic reconstruction since it has a simple structure and weak control boundaries. dual dimensional chaos has a complicated structure and more parameters [2,3]. to adjust these two factors, a dual chaotic system can be considered [4]. in this paper, dualchaotic systems that consist of two onedimensional tent and logistic maps have been designed. the chaotic attractor can be characterized by measuring the degree of sensitivity to initial conditions. lyapunov exponents (les) describe the increase of very small perturbations in different directions of the state space on a logarithmic scale, when at least one le is positive, the attractor under mailto:lwaa@kecbu.uobaghdad.edu.iq mailto:sripati_achary@yahoo.co.in mailto:mkuldc@gmail.com https://doi.org/10.22153/kej.2022.10.001 lwaa faisal abdulameer al-khwarizmi engineering journal, vol. 18, no. 4, p.p. 3244 (2022) 33 realization characterize by sensitive dependence on initial conditions property and this is termed chaotic [5]. chaos is utilized in many research areas, such as engineering, mathematics, chemistry, and biology. in communication engineering, chaos introduces important aspects in security as well as multiuser applications in cellular communications. therefore, chaotic communications is a promising technique in the next wireless generation. a compound of two 1-d chaotic maps suggests by i. aouissaoui et al. [6] for information security. which achieved a logistic-sine map based on a tent chaotic map as well as a cubic-tent map but for siso channel. the analysis of le for the proposed maps has been achieved. the bifurcation diagram was plotted to measure the chaotic range but the authors did not calculate the ber for the proposed system. j. pedro et al. [7] propose a compound of two 1d chaotic maps; logistic and tent maps for the deep zoom technique. they found that the random quality of chaos improved with prng when the chaotic parameter and a are increased for siso communication systems. but also they did not compute the ber to ensure the system performance is not affected by the changing in chaotic behavior. m. lawnik et al. [8] suggest mmap chaotic system for cryptography applications. they measured the le and plotted the bifurcation diagram. they showed that the minimum value for le for the proposed analysis was 2 and the maximum value was 12. a dual map is suggested to resolve the problem of dynamical degradation. a significant advantage in the dynamical systems analysis is the stability of the system, which can be satisfied by using the le. in this paper, the les for dual tent and logistic maps have been derived. this paper realizes the feasibility of using mimo to improve the performance of the communication system due to chaotic degradation. we have studied the performance of csk with the alamouti scheme for these dual chaotic maps under the awgn channel. the use of these schemes allows us to enhance security without degrading the ber performance. an exact method to compute the ber has been utilized and analyzed. this method considers the aperiodicity nature of the chaotic signals [9]. the simulation results refer to the combination of stbc and a single chaotic map can degrade the ber when compared to a dual chaotic map in cost of reducing the information protection. 2. iteration of chaotic map 2.1 tent map iteration consider the tent map trajectory 𝑥: [0,1] is expressed as [10] xn+1 = { xn a , 0 ≤ xn < 𝑎 1−xn 1−a , a ≤ xn < 1 …(1) the dynamical system trajectory 𝑥(𝑥) is obtained by iterating the chaotic map, i.e., 𝑥(𝑘) = 𝑓𝑘[𝑥(0)] = 𝑓({… 𝑓[𝑥(0)] … }), k=0,1,2,…… …(2) 2.2 logistic map iteration the non-linear paradigm of the logistic map is given in equation (3) [11] xn+1 = μxn(1 − xn), μ ∈ [0,4], xn ∈ (0,1) …(3) the sequence {𝑥1, 𝑥2, … 𝑥𝑛} is generated by initializing the initial value 𝑥0 ∈ (0,1) depending on the value of a parameter 𝜇 . a new sequence generates when a small change in the initial value occurs and changes in the value𝜇. the chaos state behavior occurs with the increase of 𝜇 values and achieving a chaos state ultimately. when 𝜇 > 3.75, movement from the sequence {𝑥𝑛} appears chaotic behavior. 3. dual chaotic iteration as mentioned above, a single chaotic system is attackable to be attacked by chaotic reconstruction since it has a simple structure and weak control boundaries. a 2-d chaotic map has more parameters and a complex form, but it has a more complex load. to balance these two factors, a dual chaotic map may be utilized. a dual-maps that consists of two 1-d maps has been implemented. 3.1 dual-logistic map chaos may be appeared by logistic 1 and logistic 2 such as, logistic 1: xn+1 = μxn(1 − xn), μ ∈ [3.757,4], xn ∈ (0,1) … (4) log2: xn+1 = ηxn(1 − xn), η ∈ [3.57,4], xn ∈ (0,1) … (5) where 𝜇 and η represent the control parameters. in this case, 𝑥𝑛+1 represents the output sequence of logistic 1, while 𝑦𝑛+1 represents the output sequence of logistic 2 considering 𝑦0 = 𝑥𝑛+1. so, {𝑦𝑛} is the last output of those two sequences. lwaa faisal abdulameer al-khwarizmi engineering journal, vol. 18, no. 4, p.p. 3244 (2022) 34 it is produced by composing the sequences of logistic 1 and logistic 2 [4,12]. 3.2 dual-tent map tent map 1 and tent map 2 are represented as follows, tent map 1: xn+1 = { xn a , 0 ≤ xn < 𝑎 1−xn 1−a , a ≤ xn < 1 … (6) tent map 2: yn+1 = { yn b , 0 ≤ xn < 𝑏 1−yn 1−b , b ≤ xn < 1 …(7) where 𝑎 and 𝑏 are the control parameter, 𝑥0 and 𝑦0 are initial values, 𝑥𝑛+1 is the output sequence of tent map 1, and 𝑦𝑛+1 is the output sequence of tent map 2 considering 𝑦0 = 𝑥𝑛+1. so, {𝑦𝑛} is the last output of these two sequences. it is produced by composing the two sequences of tent map 1 and tent map 2 leading to increasing the complexity of chaotic behavior. 4. lyapunov exponent consider |𝛿𝑛| = 𝑓𝑛(𝑥0 + 𝛿0) − 𝑓𝑛(𝑥0) being the 𝑛 iteration number of the chaotic sequence, 𝑥0 denotes the initial condition, and 𝛿0 be the small random number. however, le formula can be given as, 𝜆 = 1 𝑛 𝑙𝑛 | 𝛿𝑛 𝛿0 | = 1 𝑛 𝑙𝑛|(𝑓𝑛)́(𝑥0)| … (8) by expanding the term within algorithm, the approximation value of the le can be given as, 𝜆 = 1 𝑛 ∑ 𝑙𝑛|�́�(𝑥𝑖)|𝑛−1 𝑖=0 …(9) if the equation (10) have limit when 𝑛 → ∞, then the le for the orbit that begins in 𝑥0 is 𝜆 = lim 𝑛→∞ { 1 𝑛 ∑ 𝑙𝑛|�́�(𝑥𝑖)|𝑛−1 𝑖=0 } …(10) note that λ depends on 𝑥0 . for points and cycles stable, λ is negative and for chaotic attractors, λ is positive [13]. 4.1 le of single logistic [14] according to equations (3 and 10), 𝜆 = lim 𝑛→∞ { 1 𝑛 ∑ ln(𝜇) − ln (2𝜇𝑥𝑖)𝑛−1 𝑖=0 } … (11) 4.2 le of single tent [15-17] according to equs. (3) and (10), 𝜆 = ∫ 𝑙𝑛 | 1 𝑎 | 𝑑𝑥 + ∫ | 1 1−𝑎 | 𝑑𝑥 1 𝑎 𝑎 0 … (12) 4.3 le of dual logistic les of a 𝑥𝑛 sequence denoted by, 𝜆 = lim 𝑛→∞ 1 2𝑛 ln [𝐷𝑛 𝑇𝐷𝑛] … (13) whenever 𝐷𝑛 is the limit exists. uppercase t represents the transpose. from equs. (10, 11 and 13), a dual logistic map can be expressed as, let , xn+1 = μxn(1 − xn), 𝑥𝑛+1́ = 𝜇 − 2𝜇𝑥𝑛 for dual; 𝜆 = lim 𝑛→∞ 1 2𝑛 ∑ ln {[𝜇 − 2𝜇𝑥𝑛]𝑇[𝜇 − 2𝜇𝑥𝑛] −𝑛−1 𝑖=1 𝑑} = lim 𝑛→∞ 1 2𝑛 ∑ ln {𝜇(1 − 2𝑥𝑛)]𝑇[𝜇(1 −𝑛−1 𝑖=1 2𝑥𝑛)] − 𝑑} … (14) where 𝑑 is the change in initial value. 4.4 le of dual tent according to equations (10,12 and 13), a dual tent map can be derived as, let, xn+1 = { xn a , 0 ≤ xn < 𝑎 1−xn 1−a , a ≤ xn < 1 for dual; 𝜆 = lim 𝑛→∞ 1 2𝑛 {[∫ 𝑙𝑛 | 1 𝑎 | 𝑑𝑥 + 𝑎 0 ∫ | 1 1−𝑎 | 𝑑𝑥 1 𝑎 ]𝑇 [∫ 𝑙𝑛 | 1 𝑎 | 𝑑𝑥 + ∫ | 1 1−𝑎 | 𝑑𝑥 1 𝑎 𝑎 0 ] − 𝑑} …(15) 5. csk-mimo communication system let us consider x(t) as the signal that is generated by any chaotic map and defined in the previous section. in csk, the chaotic signal will occur if a ′ + 1′ is transmitted and an inverted copy of the chaotic signal will appear if ′ − 1′ is transmitted. therefore, the transmitted signal can be denoted as [18-20,24], s(t) = { x(t), if ′+1' is transmitted −x(t), otherwise …(16) let us consider the time interval of the data symbols (sl = ±1) denoted by ts , then the chip interval of the chaotic sequence will be tc(xk = x(ktc)) . however, the transmitted signal is expressed as, u(t) = ∑ ∑ slxlβ+k β−1 k=0 ∞ l=0 …(17) where 𝛽 represents the spreading factor (β = ts tc ). then, the signal received at the receiver side is denoted as, r(t)=u(t) + n(t) …(18) lwaa faisal abdulameer al-khwarizmi engineering journal, vol. 18, no. 4, p.p. 3244 (2022) 35 where n(t) represents the awgn with zero mean and variance 𝜎𝑛 2 . at the receiver, the received signal is first despreaded by generating an exact replica of the chaotic signal that is generated at the transmitter, after that the symbols are integrated over symbol duration ts . at last, the sign of the decision variable will be computed [9,21], such as, dsl = sign (sltc ∑ (xlβ+k)2 + wl) β−1 k=0 = sign(sleb (l) + wl) …(19) where sign(. ) represents the sign operator, eb (l) denotes lth bit energy and wl is the awgn computed after despreading processing. 2×2 space time block code (stbc) fig. 1 shows the block diagram of cskmimo transmitter with two antennas and two receive antenna. fig. 1 𝟐 × 𝟐 mimo-csk communication scheme. the designed symbols for stbc denoted by, s = [ s1 −s2 ∗ s2 s1 ∗ ] … (20) table. 1, the transmitted signa time interval 𝐬𝟏(𝐭)𝐟𝐫𝐨𝐦 first transmitter 𝐬𝟐(𝐭)𝐟𝐫𝐨𝐦 second transmitter [0, βtc] s1xk s2xk [βtc, 2βtc] −s2 ∗ xk+β s1 ∗xk+β table. 2, the signal received by the first receiving antenna time received signal on 𝐟𝐢𝐫𝐬𝐭 𝐫𝐞𝐜𝐞𝐢𝐯𝐢𝐧𝐠 𝐚𝐧𝐭𝐞𝐧𝐧𝐚 [0, βtc] h11s1xk + h21s2xk + nk 1 [βtc, 2βtc] −h11s2 ∗ xk+β + h21s1 ∗xk+β + nk 2 noise noise chaotic generator ෍ ⬚ 𝛽 ෍ ⬚ 𝛽 stbc decoder βtc s1,́ s2́ x(t) h11 h21 h12 h22 𝑇𝑥1 𝑇𝑥2 data alamouti encoder chaotic generator s1, s2 tx1 tx2 lwaa faisal abdulameer al-khwarizmi engineering journal, vol. 18, no. 4, p.p. 3244 (2022) 36 table. 3, the signal received by the second receiving antenna time received signal on second receiving antenna [0, βtc] h12s1xk + h22s2xk + nk 1 [βtc, 2βtc] −h12s2 ∗ xk+β + h22s1 ∗xk+β + nk 2 the tth bit energy is denoted by eb (l) = ∑ xk (l)2β k=1 . table. 4, the equivalent baseband of the symbol at 𝑹𝒙𝟏 time the equivalent baseband of the symbol at 𝑹𝒙𝟏 [0, βtc] y11 = eb(h11s1 + h21s2) + n11 [βtc, 2βtc] y21 = eb(−h11s2 ∗ + h21s1 ∗) + n21 where, n11 = ∑ nk 1β k=1 xk and 𝑁21 = ∑ 𝑛𝑘 2𝛽 𝐾=1 𝑥𝑘+𝛽 represent awgn components. table .5, the equivalent baseband of the symbol at 𝑹𝒙𝟐 time the equivalent baseband of the symbol at 𝑹𝒙𝟐 [0, βtc] y12 = eb(h12s1 + h22s2) + n12 [βtc, 2βtc] y22 = eb(−h12s2 ∗ + h22s1 ∗) + n22 n12 = n11 and 𝑁22 = 𝑁21 represent awgn components and h11, h21 , h12 and h22 are the channel coefficients for 2 × 2 scheme. the above formulas are derived in [6]. the received vector is expressed as, y = ebhs + n … (21) the data are estimated by multiplying the vector 𝑌 by the conjugate transpose of h (equation 22) and then computed by the decision variable (equation 23); ( ds1 ds2 ) = h*y …(22) the estimated bits are computed from the sign of the decision variables, s1́ = sign ds1; s2́ = sign ds2 …(23) 5.1 performance analysis let us consider the channel coefficient is constant for 2×2 stbc under the assumption of awgn. the ber formula of the proposed scheme is expressed in (24) [21,22,24]. 𝑃𝑒 (𝐸𝑏 (𝑙) ) = 1 2 𝑒𝑟𝑓𝑐(√ (ℎ11 2 +ℎ21 2 +ℎ12 2 +ℎ22 2 )𝐸𝑏 (𝑙) 𝑁0 ) now, 𝐸𝑥𝑖[𝑄{𝐸(𝑥)/√𝑉𝑎𝑟(𝑥)}] where 𝑄(𝑥) = ∫ 1 √2𝜋 exp (−𝑢2/2 +∞ 𝑥 ) 𝐵𝐸𝑅 = ෍ ℎ𝑛,𝑝 2 2 𝑛,𝑝=1 ෍ 𝐸𝑥𝑖 𝛽−1 𝑙=0 (෍ 𝑥𝑖 2 𝑁0 𝛽−1 𝑖=0 )2 = ෍ 𝐸𝑥𝑖 𝛽−1 𝑙=0 (෍ 𝑥𝑖 2 𝑁0 𝛽−1 𝑖=0 ) 1 2 (ℎ11 2 + ℎ21 2 + ℎ12 2 + ℎ22 2 )𝐸𝑏 (𝑙) ∑ 𝑥𝑖 2𝛽−1 𝑖=0 =eb (l) is the chaotic symbol energy, and 𝐸𝑥𝑖 = ∫ p (eb (l)) deb (l)∞ 0 , the ber formula for 2×2 stbc is formulated as, ber = ∫ 1 2 ∞ 0 erfc (√ (h11 2 +h12 2 +h21 2 +h22 2 )eb (l) n0 ) p (eb (l)) deb (l) … (24) where p (eb (l)) is the pdf of the eb (l) . the ber formula resulted from integration given in equation (24). to compute the integral in equation (24), the distributed energy must be considered. because of the pdf consider to be intractable, the method to compute the ber is evaluating the histogram of eb (l) followed by a numerical integration [18,19,18]. fig. (2) presents the histogram of the eb (l) , for 50000 samples obtained by simulation and 𝛽=4. lwaa faisal abdulameer al-khwarizmi engineering journal, vol. 18, no. 4, p.p. 3244 (2022) 37 fig. 2 𝐄𝐛 (𝐥) histogram. applying numerical integration, the ber formula is expressed as, ber = ∑ 1 2 erfc (√ (h11 2 +h12 2 +h21 2 +h22 2 )eb (l) n0 ) p(eb (l))m l=1 … (25) in the above equations, 𝑚 denotes the number of histogram classes and p (eb (l))is the probability of the energy in interval centered on eb (l) . 6. results and discussions fig.3 shows the single logistic map providing the chaotic behavior beyond 𝜇 = 3.57. this map has more randomness 𝜇 = 3.8 and le equals 0.5. fig.4 presents the single tent map. it is observed that this map has chaotic properties within the range (0,1) of a control parameter (a). it has more randomness when the value of (a) is greater than 0.5 and le equals 0.85. a dual logistic is provided in fig.5. it has more randomness when 𝜇 > 2.35 and 𝜇 < 4. more randomness appeared at 𝜇 = 4 and le equals 0.81. fig.6 presents the dual tent which has chaos properties in the range (0,1) of 𝑎 . it has more randomness when 𝑎 = 0.5 and le at equals 1.2. we observed from fig. 3 and fig. 4 that when a very small change in initial values say 10-16, a new chaotic sequence is generated completely different from the current state. therefore, with increasing the time of iteration more than 20 times, the difference exponentially increases. for the dual logistic map in fig. 5, this difference appears with increasing the iteration time more than 40 times, after this value, the difference exponentially increases. in fig.6, the dual tent map has the difference between two sequences is very sensitive to a very small change in initial conditions. however, this map shows better sensitivity to initial conditions. whereas, the single tent map provides the best sensitivity than dual single and logistic maps according to results obtained from le. table (6) summarizes the values of les for presented chaotic maps table 6, values of le chaotic map le single logistic 0.5 single tent .0.85 dual logistic 0.81 dual tent 1.2 from the above table, it is observed that the dual tent has the most randomness whereas the single logistic map has the least randomness. in fig.7, the ber is degraded for single map when a 2 × 2 is considered for the system. also, for a dual tent, when the system is compensated with 2 × 2 stbc, the snr will gain 0.5 db as compared to 2 × 2 single logistic for the same ber under the awgn assumption. it is noted that there is a tradeoff between the randomosity and ber performance. so, the ber performance can be achieved by implementing 2 × 2 single tent map at the cost of reducing randomosity. from figs. 3,4, 5, and 6, we observed that chaotic maps give highly distinct sequences as 1.85 1.855 1.86 1.865 1.87 1.875 0 0.5 1 1.5 2 2.5 x 10 4 bit energy n0 . of s am pl es lwaa faisal abdulameer al-khwarizmi engineering journal, vol. 18, no. 4, p.p. 3244 (2022) 38 compared to the pn sequence generator. the degree of distinctness is more for the dual chaotic map as compared to the single chaotic map. now, let us suppose that 𝑥𝑛 and 𝑦𝑛 are twosequence with length 𝑁. the auto-correlation and the cross-correlation are defined in equations (26 and 27) respectively [4]. 𝑅𝑥(𝑗) = 1 𝑁 ∑ 𝑥𝑖𝑥𝑖+𝑗 𝑁 𝑖=1 …(26) 𝑅𝑥𝑦(𝑗) = 1 𝑁 ∑ 𝑥𝑖𝑦𝑖+𝑗 𝑁 𝑖=1 …(27) where 𝑁 is the sequence’s length and 𝑗 is the distance between two chaotic elements. fig.8 shows the auto-correlation of dual tent. the auto-correlation is maximum at zero time shift. fig. 9 presents that the single tent map provides a cross correlation function near zero (maximum value 0.0085) when compared to dual tent (highest value 0.028). however, the two sequences of single tent satisfy the orthogonality property more than dual tent map fig. 3. the difference between two single logistic and its le. 0 10 20 30 40 50 60 70 80 90 100 -4 -2 0 2 4 6 8 x 10 -14 iterations d if fe re n c e b e tw e e n t w o s e q u e n c e s single logistic map lwaa faisal abdulameer al-khwarizmi engineering journal, vol. 18, no. 4, p.p. 3244 (2022) 39 fig. 4. a) the difference between two single tent and its le. 0 10 20 30 40 50 60 70 80 90 100 -1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1 iterations d if fe re n c e b e tw e e n t w o s e q u e n c e s single tent map 0 10 20 30 40 50 60 70 80 90 100 -1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1 iterations d if fe re n ce b et w ee n t w o s eq u en ce s dual logistic logistic lwaa faisal abdulameer al-khwarizmi engineering journal, vol. 18, no. 4, p.p. 3244 (2022) 40 fig. 5. the difference between two dual logistic and its l.e fig. 6. the difference between two dual tent and its le. 0 10 20 30 40 50 60 70 80 90 100 -1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1 iterations d if fe re n ce b et w ee n t w o s eq u en ce s dual tent maps lwaa faisal abdulameer al-khwarizmi engineering journal, vol. 18, no. 4, p.p. 3244 (2022) 41 fig. 7. ber for single and dual maps. fig. 8. auto-correlation of dual tent. lwaa faisal abdulameer al-khwarizmi engineering journal, vol. 18, no. 4, p.p. 3244 (2022) 42 fig. 9. cross-correlation of single and dual tent. 6. conclusions the data encryption based on the dual chaotic presented in this work has excellent randomness. the les for the single and dual maps have been computed numerically. in this work, the exact ber for dual and single chaotic maps modulated csk 2 × 2 stbc under awgn has been investigated. the final results show that the randomness of the dual tent map is better than the single tent map, single logistic map, and dual logistic map. as well as the 2 × 2 csk-mimo gives a better ber performance as compared with the siso system. 7. references [1] k. daniela and e. marcio, “on the power spectral density of chaotic signals generated by skew tent maps,” ieee international symposium on signals, circuits and systems”, vol. 1, pp. 1-4, 2007. 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[16] l. abdulameer., d. jokhakar, u. sripati and m. kulkarni: ber performance enhancement for secure wireless communication systems based on chaotic mimo techniques., procedding of the international conference on communication and electronics system design, 2013. [17] r. sankpal, a. vijaya, image encryption using chaotic maps. a survey, lecture notes in networks and systems, springer, p.p. 835844, 2014. [18] s. das, k. mandal, and m. chakraborty, “lmmse equalized dcsk communication system over a multipath fading channel with awgn noise”, proceeding of the third international conference on computer, communication, control and information technology (c3it), p.p 1-4, 2015. [19] v. manikandan & rengarajan amirtharajan, “on dual encryption with rc6 and combined logistic tent map for grayscale and dicom”,” multimedia tools and applications”, p.p. 130, 2021. [20] a. imoize , a. ibhaze , a. atayero , and k. kavitha, “standard propagation channel models for mimo communication systems”, “hindawi wireless communications and mobile computing”, pp. 1-36, 2021. [21] r. dhia’a, “design a security network system against internet worms”, “alkhwarizmi engineering journal”, vol. 8, no. 3, pp 40 – 52, p.p. 1-13, 2012. [22] r. yamazaki, y. shimada, and t. ikeguchi, “chaos mimo system with efficient use of information of bits”, “nolta, ieice”, p.p. 1-15, 2020. [23] i. kadhem, “a new audio steganography system based on auto-key generator”, “alkhwarizmi engineering journal”, vol. 8, no. 1, p.p. 27 – 36, 2012. [24] l. abdulameer, analysis and design of reliable and secure chaotic communication systems for optical and wireless links, dept. of electronics and communication engg., nitk, 2014. https://ieeexplore.ieee.org/xpl/conhome/5602791/proceeding https://ieeexplore.ieee.org/xpl/conhome/4569857/proceeding https://ieeexplore.ieee.org/xpl/conhome/4569857/proceeding https://ieeexplore.ieee.org/xpl/conhome/4569857/proceeding http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=6754860&url=http%3a%2f%2fieeexplore.ieee.org%2fxpls%2fabs_all.jsp%3farnumber%3d6754860 http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=6754860&url=http%3a%2f%2fieeexplore.ieee.org%2fxpls%2fabs_all.jsp%3farnumber%3d6754860 http://ieeexplore.ieee.org/search/searchresult.jsp?searchwithin=p_authors:.qt.das,%20s..qt.&newsearch=true http://ieeexplore.ieee.org/search/searchresult.jsp?searchwithin=p_authors:.qt.mandal,%20s.k..qt.&newsearch=true http://ieeexplore.ieee.org/search/searchresult.jsp?searchwithin=p_authors:.qt.chakraborty,%20m..qt.&newsearch=true http://ieeexplore.ieee.org/xpl/mostrecentissue.jsp?punumber=7055073 http://ieeexplore.ieee.org/xpl/mostrecentissue.jsp?punumber=7055073 http://ieeexplore.ieee.org/xpl/mostrecentissue.jsp?punumber=7055073 http://ieeexplore.ieee.org/xpl/mostrecentissue.jsp?punumber=7055073 http://ieeexplore.ieee.org/xpl/mostrecentissue.jsp?punumber=7055073 (2022) 32-44، صفحة 4العدد، 18مجلة الخوارزمي الهندسية المجلد لواء فيصل عبد االمير 44 تحسين اداء منظومة االتصاالت الفوضوية الثنائية باستخدام تقنية الهوائيات المتعددة لواء فيصل عبد األمير* اودبي سريباتي** مولدير كولكرني*** العراق /جامعة بغداد /كلية الهندسة الخوارزمي /قسم هندسة المعلومات واالتصاالت* دالهن /قسم هندسة االلكترونيك واالتصاالت /المعهد الوطني التكنولوجي كارناتاكا**،*** lwaa@kecbu.uobaghdad.edu.iq*البريد االلكتروني: sripati_achary@yahoo.co.in:البريد االلكتروني** mkuldc@gmail.com:البريد االلكتروني*** الخالصة تعد من الخيارات الممتازة الفوضويةان الحفاظ على سرية المعلومات عند انتقالها خالل الوسط من والى المستخدم تعد من االمور الضرورية جدا. االشارة جدا فياالشارة ال تكرر نفسها بعد مدة من الزمن وان اي تغيير حتى لو كان صغيرا لتشفير االشارات وخصوصا انها تمتاز عن الخوارزميات االخرى بكون فوضوية من االحادية مما أكثر. االشارة الفوضوية الثنائية تمتاز بكونها القيم االبتدائية سوف يولد اشارة جديدة مما يصعب على المتنصتين استراق االشارة الفوضوية الثنائية وقد تم قياس لإلشارةالفوضوية االحادية ونوعين مماثلين لإلشاراتيولد اشارة معقدة جدا بالنسبة للمتنصت. في هذا البحث، تم تصميم نوعين (. ايضا تم في هذا البحث استخدام تقنية متعددة lyapunov exponent (le)مية لكل نوع وتتمثل بـ )مدى فوضوية كل اشارة من خالل اشتقاق خوارز )العالقة العكسية بين الهوائيات لتحسين االداء العام لمنظومة االتصاالت لكون استخدام االشارات الفوضوية يؤدي الى تقليل االداء بسبب زيادة سرية المعلومة فوضوية من بقية االنواع المستخدمة في البحث. أكثرمما يعني انها (le)اعطت اعلى قيمة من الـ dual chaotic mapالنتائج بينت بأن االنتروبي واالداء(. االخرى المستخدمة. باألنواعاداء مقارنة أحسنيقدم single chaotic mapمع 2x2ايضا من خالل استخدام تقنية الهوائيات المتعددة تبين ان استخدام mailto:lwaa@kecbu.uobaghdad.edu.iq mailto:sripati_achary@yahoo.co.in**البريد mailto:sripati_achary@yahoo.co.in**البريد mailto:mkuldc@gmail.com***البريد mailto:mkuldc@gmail.com***البريد access article under the cc by license:this is an open al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 21, no. 3, september, (2025), pp. 1224 examination the corrosion inhibition of synthesized azo-schiff bases compounds from (p-fluorophenyl)-1,3,4-thiadiazoles for carbon steel alloy in acidic medium khadija najah zaidane 1*, and ahmed wahed naser 2 1 department of petroleum refining and gas technology engineering, college of chemical engineering, university of technology, baghdad, iraq 2 department of chemical engineering, college of engineering, university of baghdad, baghdad, iraq *corresponding author’s email: khadija89najahz@gmail.com (received 28 july 2024; revised 6 september 2024; accepted 25 september 2024; published 1 september 2025) https://doi.org/10.22153/kej.2025.09.004 abstract new azo-schiff base compounds were prepared by different processes using (p-fluorophenyl)-1,3,4-thiadiazoles, and their role as corrosion inhibitors for carbon steel alloy in acidic media such as 0.1 m hcl at 298 k was investigated. spectroscopic methods such as ft-ir and nmr were used to characterise the compounds, and potentiodynamic polarization curves were employed to evaluate their corrosion inhibition. p-aminoacetophenone was react withed 2-(5(4-fluorophenyl)-1,3,4-thiadiazol-2-yl) acetohydrazide (a1) to prepare n ′ -(1-(4-aminophenyl) ethylidene)-2-(5-(4fluorophenyl)-1,3,4-thiadiazol-2-yl) acetohydrazide (a2). azo-schiff bases (a3-a6) were synthesised by combining the prepared diazonium salts with different phenols. these compounds’ structures were changed to improve their ability to prevent corrosion in a range of industrial settings, especially for metals exposed to acidic environments. the inhibitory efficiency percentage was between 76% and 90%. at 90%, the synthetic medication (a6) obtained the highest value. the formed protective adsorption coating on the steel surface was the reason for the improved inhibitor activity. these findings imply that the artificial azo-schiff bases show promising application as corrosion inhibitors for carbon steel in acidic settings. applications in sectors where corrosion resistance is crucial may benefit from this knowledge. keywords: potentiodynamic; polarisation; thiadiazol; aminoacetophenone; hydroxy naphthalene; carbon steel; fourier transform infrared spectroscopy; dimethyl sulfoxide. 1. introduction the chemical, electricity and petroleum industries, frequently use iron and its alloys because of their low cost, strong mechanical properties and simplicity of manufacture [1, 2]. many industries are affected by the expensive problem of corrosion, especially those that depend on metal parts and buildings that are subjected to severe conditions [3]. thus, efficient corrosion prevention techniques must be developed. one method is to use anticorrosion materials. corrosion inhibitors are classified according to their chemical structure and mechanism, with organic inhibitors being the most common [4-6]. chemicals known as corrosion inhibitors are used in extreme situations to lessen or prevent metal corrosion. these materials either alter the environment or apply a protective layer to the metal surface to stop corrosion [7]. their application is essential in industries where metals are regularly subjected to harsh environments, such as those that are acidic, saline or rich in oxygen. corrosion inhibitors are essential because they extend the life of metal structures, reduce maintenance and replacement costs and guarantee mailto:khadija89najahz@gmail.com https://doi.org/10.22153/kej.2025.09.004 khadija najah zaidane al-khwarizmi engineering journal, vol. 21, no.3, pp. 1224 (2025) 13 the safe and dependable operation of industrial systems. they slow down the deterioration of metals and stop the discharge of toxic byproducts into ecosystems, both of which contribute to environmental protection. hence, they are essential to sectors including construction, chemical processing, water treatment and oil and gas [7-9]. investigations demonstrated that organic inhibitors comprising heteroatoms such as oxygen, phosphorous, sulphur and nitrogen are exceptionally effective at lowering corrosion in a variety of acidic solutions. owing to their high polarisability and low electronegativity, these inhibitors function by promoting electron transport to atoms’ vacant orbitals and enabling atoms and functional groups to cover substantial metallic surface regions [10]. organic compounds, especially derivatives of thiadiazol, have recently attracted attention as possible corrosion inhibitors. their distinctive molecular structures are characterised by a fivemembered heterocyclic ring composed of sulphur and nitrogen atoms [11]. the inclusion of the (pfluorophenyl) moiety increases the electron density of the thiadiazol ring and may enhance the adsorption characteristics of the resulting azoschiff bases. in acidic media where metal corrosion is most severe, this structural alteration renders these compounds potent corrosion inhibitors [12]. n-heterocyclic compounds can effectively suppress iron or steel corrosion under a wide range of harsh conditions. many strategies are used to counteract corrosion, each suited to different types of metals and surroundings. important techniques include passivation, which encourages the production of a persistent oxide layer, mixed inhibition and adsorption inhibition, in which organic inhibitors are adsorbed onto metal surfaces to form protective barriers [13]. one of the best ways to prevent corrosion in metals is to employ inhibitors. numerous methods have been used to investigate metal corrosion. one of the most practical ways to prevent corrosion in acidic conditions is to utilise chemical inhibitors [14]. the majority of highly effective acid inhibitors are made of organic substances containing sulphur, phosphorus, oxygen and nitrogen. therefore, research on the connection between adsorption and corrosion inhibition is crucial [15]. the schiff base, which is the product of the condensation of amines with aldehydes or ketones, has good inhibitive qualities. these ligands are remarkably members of the class in coordination chemistry. their c=n groups are responsible for this ability. schiff bases adhere to and shield the metal/solution surface. in this work, azo-schiff base derivatives were studied to explore their corrosion inhibition of carbon steel in 0.1 m hydrochloric acid solution. table 2 provides the chemical structures of these derivatives. the heteroatoms in the heterocyclic structure of nʹ-(1-(4-((2-amino-4-hydroxyphenyl) diazenyl) phenyl) ethylidene)-2-((5-(4-fluorophenyl)-1,3,4thiadiazol-2-yl) amino) acetohydrazide (a6) may function as an efficient corrosion inhibitor. novel azo-schiff bases were created using p-fluorophenyl1,3,4-thiadiazoles in order to prevent carbon steel from corroding in acidic settings at room temperature (298 k). 2. materials and methods 2.1. chemicals and materials all substances used were supplied by merck, bdh, fluka and sigma–aldrich chemicals companies, germany. the alloy used in this work was carbon steel (c45) with the following chemical composition: table 1, c45 carbon steel’s chemical constitution metal c% si% mn % s% p% cu% ni% cr% fe% carbon steel 45 0.36-0.42 0.150.30 1.001.40 0.05 0.05 0.50 0.20 0.20 96.8897.49 bruker ultrashield 500 mhz spectrophotometer was used to record nmr (1h-nmr and 13c-nmr) spectral data with dmso as a solvent at the university of baghdad’s college of sciences. a shimadzu ft-ir 8300 fourier transform infrared spectrophotometer was used to calculate infrared spectra for the prepared derivatives as a kbr disc in the wave range of 400–4000 cm¯1. a hot stage gallen kamp melting point apparatus (m. p.) was used in an open capillary system to determine the melting point. an advanced potentiostat named mlab 200 (2007) bank (electronic-intelligent controls gmbh) complete with all accessories and three electrode cells was used for polarisation measurements at the khadija najah zaidane al-khwarizmi engineering journal, vol. 21, no.3, pp. 1224 (2025) 14 university of baghdad’s college of science, department of chemistry. 2.2. measurements and experimental setup 2.2.1. experimental setup the corrosion inhibition of carbon steel using an organic inhibitor in 0.1 m hcl at 298 k was examined through potentiostat polarisation curves. the experimental setup involved carefully preparing carbon steel specimens by polishing, cleaning and drying to ensure uniformity. the specimens are immersed in an acidic corrosive solution containing the organic inhibitor. a threeelectrode electrochemical cell comprising carbon steel as the working electrode, a saturated calomel electrode (sce) as the reference electrode and platinum as the counter electrode was utilised. polarisation curves were produced by applying a controlled potential sweep with a potentiostat to investigate anodic and cathodic reactions. the obtained polarisation curves were used to calculate the corrosion rate and effectiveness of the organic inhibitor by determining the corrosion potential (ecorr), corrosion current density (icorr) and other electrochemical parameters. as shown in figure 1, this configuration offers a thorough assessment of how the organic inhibitor inhibits corrosion in acidic environments by affecting anodic and cathodic corrosion processes. fig. 1. complete system set-up for polarisation measurements an electrochemical cell known as the corrosion cell was used to experimentally evaluate the carbon steel specimens for electrochemical corrosion [16]. the 1 l pyrex corrosion cell consisted of a threeelectrode system whose electrodes (working, axillary and reference) were submerged in an electrolyte solution. (1) working electrode: the carbon steel specimen served as an electrode during the operation. the metal was reduced or oxidised at the working electrode by an anodic or cathodic process. studies on corrosion found these reactions to be of interest. (2) axillary electrode: during the test, the working electrode where the cathodic or anodic reaction occurs was supplied with current by the axillary electrode, which is made of high-purity platinum metal. (3) reference electrode: a calomel electrode was used to allow the potentiostat to regulate the voltage between the working and reference electrodes. the login tube serves as a salt bridge, minimises the potential drop caused by resistance at the interface between the working electrode and the electrolyte and controls the reference electrode’s ideal location. 2.2.2. synthesis of inhibitors a) synthesis of nʹ-(1-(4-aminophenyl) ethylidene)2-((5-(4-fluorophenyl)-1,3,4-thiadiazol-2-yl) amino) acetohydrazide (a2) [17, 18]: 20 ml of 100% ethanol was used to dissolve compound (a1) (0.5 g, 0.001 mol). glycolate acetic acid and p-aminoacetophenone were added in small amounts to this solution (0.03). for 10 hours, this combination underwent reflux. the precipitate was removed from the ethanol by filtering, drying and recrystallisation after cooling (a2) (85% yield, mature point (m. p.) 471.15 k– 473.15 k, yellow precipitation; m. p. 478.15 k– 480 k, yield 96%, yellow precipitate). khadija najah zaidane al-khwarizmi engineering journal, vol. 21, no.3, pp. 1224 (2025) 15 b) general synthesis method for azo-schiff bases (a3–a6) [19, 20]: after dissolving compound a2 (0.007 mol) in 15 ml of concentrated hcl and 15 ml of distilled water, the mixture was cooled in an ice bath until it reached a temperature between 0 and 278.15 k. the nano2 solution, which was prepared by dissolving 0.47 g or 0.007 mol into 5 ml of distilled water, was dropwise added to the reaction mixture, which was then agitated for 10 minutes. the mixture was slowly and carefully added to a solution containing various phenols (0.007 mol) such as phenol, β-naphthol, pnitrophenol, salcildehyde and 3-aminophenol in 60 ml of 10% naoh at 0–278.15 k. the mixture was then agitated for 30 minutes. hot steam was used to dry the coloured product after it was filtered and cleaned with cooled distilled water. nʹ-(1-(4-((2-hydroxynaphthalen-1-yl) diazenyl) phenyl) ethylidene)-2-((5-(4-flourophenyl)-1,3,4thiadiazol-2-yl) amino) acetohydrazide (a3): yield 70%, m. p. 363.15 k–365.15 k, burgundy precipitate nʹ-(1-(4-((2-hydroxy-5-nitrophenyl) diazenyl) phenyl) ethylidene)-2-((5-(4-flourophenyl)-1, 3, 4thiadiazol-2-yl) amino) acetohydrazide (a4): yield 80 %, m. p. 506.15 k–508.15 k, pale orange precipitate nʹ-(1-(4-((3-formyl-4-hydroxyphenyl) diazenyl) phenyl) ethylidene)-2-((5-(4-flourophenyl)-1, 3, 4thiadiazol-2-yl) amino) acetohydrazide (a5): yield 83%, gummy, greenish brown precipitate nʹ-(1-(4-((2-amino-4-hydroxyphenyl) diazenyl) phenyl) ethylidene)-2-((5-(4-flouro phenyl)-1, 3, 4thiadiazol-2-yl) amino) acetohydrazide (a6): yield 82%, m. p. 430.15 k–432.15 k, orange precipitate 2.3. corrosion measurement carbon steel alloy was utilised, and its chemical composition is detailed in table 1. before the corrosion test, the carbon steel electrode underwent polishing with emery papers grade 800–1200. distilled water, acetone and alcohol were used for ultrasonic cleaning, followed by drying in dry air. a 0.1 m hcl aqueous solution, the testing electrolyte, was prepared by diluting analar grade 37% hcl with ultrapure water. polarisation measurements were conducted using a standard corrosion cell. the setup included a corrosion cell with three electrodes: a working electrode made of carbon steel alloy, a counter electrode and a reference electrode sce. all potential values were referenced to the sce. electrochemical experiments were performed over a potential range of 200 mv. before measurements, the working electrode was immersed in the test solution for 900 seconds to achieve a steady-state open circuit potential (eocp). all tests were carried out at 298 k using a cooling or heating circulating water bath [21]. 3. results and discussion 3.1. synthesis and analysis the azo-schiff base compounds produced from (p-fluorophenyl)-1,3,4-thiadiazoles were studied using analytical techniques, ft-ir and nmr. the ft-ir spectra of the compounds (a3–a6) in figures 4–10 confirmed the formation of azo dyes via the appearance of a stretching band of oh at 3200–3433 cm−1 [3]. ft-ir spectral data also showed the appearance of a stretching band of n=n at 1425 cm−1. all details of the ftir spectral data of compounds a3–a6 are listed in table 2. the presence of distinctive c=n stretching vibrations in the ft-ir spectra verified the synthesis of schiff bases. the molecular structure was revealed by nmr spectroscopy, which also verified that the pfluorophenyl group was successfully incorporated into the 1,3,4-thiadiazole ring. compounds a3 and a5) were identified by 1hnmr and 13cnmr: new values appeared at δ = 13.03–13.13 ppm attributed to the oh proton, and a new signal at δ = 1.13, 1.17 ppm indicated binding the (ch3) group of compounds (a3, a5). in contrast, the 13cnmr spectrum of compound a3 displayed characteristic signals δ (ppm) at 39.7, 154.38 and 170.34 attributed to ch3, (c-oh) and (c=n), receptively. the 1hnmr and 13cnmr spectra of compounds a3 and a5 are listed in tables 3 and 4 and displayed in figures 8–10. khadija najah zaidane al-khwarizmi engineering journal, vol. 21, no.3, pp. 1224 (2025) 16 table 2, ftir spectral data of compounds a3–a6 com. no. str. ftir spectral data cm-1 ν (n-h) ν(c-h) aroma. ν (c-h) alipha. ν(c=n) ν(c=o) ν(n=n) others a3 3180 3064 2887 1623 1689 1425 (c-f) 1296 (oh) 3200 a4 3269 3064 2920 2854 1602 1687 1425 (c-f) 1292 (oh) 3433 a5 3101 3064 2960, 2827 1687 1604 1425 (c-f) 1286 a6 3200 3064 2960 2885 1687 1602 1425 (c-f) 1288 table 3, 1hnmr spectral data (δ ppm) of compounds a3 and a5 com. no. structure 1hnmr spectral data (δ ppm) a3 1.13 (s, 3h, -ch3); 2.53 (d, 2h, -ch2); 7.80 (s, h, nh); 6.36-8.89 (m, 14h, ch-ar); 13.13 (s, h, oh) a5 1.13 (s, 3h, -ch3); 2.8 (d, 2h, -ch2); 7.41 (s, h, nh); 6.36-8.58 (m, 14h, ch-ar); 10.12 (s, hc=o); 13.03 (s, h, oh) table 4, 13cnmr spectral data (δ ppm) of compound a3 com. structure 13cnmr spectral data (δ ppm) a3 39.7 (ch3); 124.90-129.37 (c-ar); 136.47 (c-ch3); 148.16 (c-f); 154.38 (c-oh); 170.34 (c=n) khadija najah zaidane al-khwarizmi engineering journal, vol. 21, no.3, pp. 1224 (2025) 17 3.2. potentiodynamic polarisation measurements the corrosion inhibition performance of the synthesised compounds was evaluated by conducting potentiodynamic polarisation in acidic media. table 2 shows that compared with that in the blank solution, the corrosion current density (icorr) in the presence of the azo-schiff base inhibitors significantly decrease from 563.2 µa/cm2 to 137.3, 102.0, 74.28 and 56.26 µa/cm2 for a4, a3, a6 and a5, respectively. the decrease in corrosion rate corresponded to an inhibitory efficiency percentage (ie%) of 90% for compound a5 as shown in figure 2 and table 5. %ie = (icorr)o−(icorr) (icorr)o ∗ 100, (1) where (i corr) is the corrosion current density in the absence of inhibitors, (icorr) is the corrosion current density in the presence of inhibitors [22, 23]. figure 1 shows the polarisation curves of the blank and inhibited solutions with different synthesised compounds. the extent of rusting in 0.1 m hcl solution and the cathodic and anodic tafel slopes in the presence and absence of the inhibitor molecules were extrapolated. the current corrosion density (icorr) and corrosion potential (ecorr) were calculated. table 5 displays the calculated corrosion potential (ecorr, mv), corrosion current density score (a/cm2), cathodic and anodic tafel slopes (mv/dec) and protection effectiveness pe% [24]. the corrosion potential (ecorr) shifted to a more active potential for all the compounds, indicating a change in the natural surface. as a result, the inhibitors were adsorbed on the carbon steel surface. the anodic (ꞵa) and cathodic (ꞵc) slopes were changed significantly (table 5 and figure 2, indicating that the compounds act as a mixed-type inhibitor affecting anodic and cathodic reactions. table 5, corrosion parameters for blank and compound in hcl solutions and different compounds. comp. blank a3 a4 a5 a6 -ecorr (v) -0.385 -0.717 -0.743 -0.862 -0.812 icorr (µa/cm2) 563.2 102.0 137.3 56.26 74.28 i corr./ r )a/cm² ( 0.001 2.040e-4 2.747e-4 1.125e-4 1.486e-4 resis. )ω( 28.96 1209 955.8 1836 1842 -bc (mv/dec) 0.055 0.502 0.561 0.577 0.722 ba (mv/dec) 0.120 0.655 0.656 0.405 0.559 corr. rate, (mm/y) 5.529 1.001 1.348 0.552 0.729 ie% 82 76 90 87 fig. 2. polarisation curve of carbon steel in 0.1 m hcl and inhibited solutions with four synthesised compounds (a3, a4, a5 and a6) at 298 k 3.3. mechanism of inhibition the inhibitory effectiveness of the heteroatoms followed the sequence o < n < s, which is attributed to the presence of c=n groupings. azoschiff bases demonstrate their inhibitory effectiveness mainly through their adsorption on the metal/solution interface [3, 25], creating a barrier khadija najah zaidane al-khwarizmi engineering journal, vol. 21, no.3, pp. 1224 (2025) 18 that keeps corrosive substances from getting to the metal. the lone pair electrons on the schiff base’s nitrogen atoms and the π-electrons of the aromatic rings, which interact with the metal surface, are probably involved in the adsorption process. by increasing the electron density surrounding the schiff base, the use of a p-fluorophenyl group leads to good adsorption and high inhibitory efficiency. additionally, the p-fluorophenyl group’s electrondonating action is probably responsible for the observed rise and fall in icorr values [26]. scheme 1. synthesis route of compounds a3–a6 fig. 3. ftir spectrum of compound a3 khadija najah zaidane al-khwarizmi engineering journal, vol. 21, no.3, pp. 1224 (2025) 19 fig. 4. ftir spectrum of compound a4 fig. 5. ft-ir spectrum of compound a5 khadija najah zaidane al-khwarizmi engineering journal, vol. 21, no.3, pp. 1224 (2025) 20 fig. 6. ft-ir spectrum of compound a6 fig. 7. 1hnmr spectral data of compound a3 fig. 8. 13cnmr spectrum of compound a3 khadija najah zaidane al-khwarizmi engineering journal, vol. 21, no.3, pp. 1224 (2025) 21 fig. 9. 1hnmr spectrum of compound a5 4. conclusions azo-schiff base compounds were synthesised from (p-fluorophenyl)-1,3,4-thiadiazoles, and their potential as potent corrosion inhibitors for metallic materials in acidic environments was assessed. their structures were confirmed using ft-ir, ¹h nmr and ¹³c nmr. compounds a3–a6 were evaluated for their capacity to prevent the surface corrosion of carbon steel in an acidic environment. these substances showed potent anticorrosive properties by forming an adsorbed layer on the carbon steel’s surface. the synthetic azo-schiff bases exhibited improved structural properties, particularly stability and adsorption capacity for the p-fluorophenyl moiety on the metal substrate. these improvements led to a high inhibition efficiency, demonstrating the ability of these compounds to stop metal corrosion. the findings highlight the importance of molecular design in creating potent corrosion inhibitors. the azo-schiff base compounds derived from (p-fluorophenyl)-1,3,4-thiadiazoles provide good corrosion protection and are an eco-friendly substitute for traditional inhibitors. this research advances our knowledge of the mechanisms underlying corrosion inhibition and encourages the development of creative, longlasting corrosion prevention techniques. future studies should concentrate on enhancing the structural properties of these materials and analysing their performance in various industrial environments. comprehensive investigations on the stability and environmental impact of these inhibitors would be beneficial to guarantee legal compliance and real-world use. references [1] r. sehrawat, p. vashishth, h. bairagi, s. k. shukla, h. kumar, g. ji, et al., "coordination bonding and corrosion inhibition characteristics of chalcone compounds for metals: an inclusive review based on experimental as well as theoretical perspectives," coordination chemistry reviews, vol. 514, p. 215820, 2024. 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( 2025) 12-24، صفحة 3، العدد21مجلة الخوارزمي الهندسية المجلدخديجة نجاح زيدان 24 1,3,4-فلوروفينيل( -دراسة تثبيط التآكل لمركبات قواعد اآلزو شيف المحضرة من )ب ياديازول لسبيكة الفوالذ الكربوني في الوسط الحمضيث خديجة نجاح زيدان1*, احمد وحيد ناصر2 التكنلوجية، بغداد، العراق هندسة كيمياوي، الجامعة قسم هندسة تكرير النفط وتكنلوجيا الغاز، 1 العراق بغداد، بغداد، جامعة الهندسة،كلية الكيمياوية، قسم الهندسة 2 khadija89najahz@gmail.comالبريد االلكتروني: * لمستخلص ا شيف بطرق مختلفة، وثمت دراسة قواعدها كمثبطات التآكل لسبائك الفوالذ الكربوني في حامض الهيدروكلوريك بتركيز -تحضير لمركبات قواعد آزوالتم رت المركبات الجديدة باستخدام . كلفن في الوسط الحامضي 298موالري عند درجة حرارة 0.1 ثياديازول، وطرق طيفية -4، 3، 1-(فلوروفينيل-بارا)ُحض ِّ فة مدى فعالية مثل تحويل فورييه لألشعة تحت الحمراء والرنين المغناطيسي النووي لتحديد هوية المركبات، ومنحنيات االستقطاب الجهدي الديناميكي لمعر التآكل بارا. تثبيط مع -يتفاعل ( أمينوفينيل-4)-n '-(1لتحضير ( a1) أسيتوهيدرازيد ( يل-2-ثياديازول-3،4، 1-(فلوروفينيل-4)-5)-2أمينوأسيتوفينون من أمالح الديازونيوم الُمحضرة مع ( a3-a6)شيف -ُصنعت قواعد آزو(. a2)أسيتوهيدرازيد ( يل-2-ثياديازول-3،4، 1-(فلوروفينيل-4)-5)-2-(إيثيليدين لت تركيبات هذه المركبات لتحسين قدرتها على منع التآكل في مجموعة من البيئات الصناعية، وخاصةً للمعادن المعرضة للبيئات الحمض. فينوالت مختلفة ِّ . ية ُحو ويُعزى تحسن نشاط المثبط إلى تكوين .أعلى قيمة( a6)، حقق الدواء االصطناعي %90عند . %90و %76بين %( ie)تراوح نطاق نسبة الكفاءة المثبطة ة جدًا لالستخدام كمثبطات تآكل الفوالذ الكربوني في البيئات شيف االصطناعية واعد -تشير هذه النتائج إلى أن قواعد آزو. طبقات امتزاز واقية على سطح الفوالذ . وقد تستفيد التطبيقات في القطاعات التي تُعد فيها مقاومة التآكل أمًرا بالغ األهمية من هذه المعرفة. الحمضية اآلزو قاعدة مركبات تصنيع تم البحث هذا من-في حرارة واستخدمت 1,3,4-thiadiasols(p-fluorophenyl) شيف درجة في 298عند كلفن سبيكة الفوالذ الكربوني. تمت دراسة تآكل الفوالذ الكربوني في الظروف الحامضية باستخدام منحنى االستقطاب لتآكل موالري كمثبطات 0.1الهايدروكلوريك ثياديازول-1,3,4فلوروفينيل( أسيتوهيدرازيد )-4)-5)-2-أمينو فينيل( إيثيليدين1-(4-))-'n ليشكل (a1) أمينو أسيتوفينون والمركب-الديناميكي. يتكثف بارا وخضعت هذه المواد لتعديالت (a3-a6) خضعت أمالح الديازونيوم المحضرة والفينوالت المختلفة لعملية اقتران لتكوين قواعد آزو شيف (a2) (ييل-2 نسبة كفاءة التثبيط هيكلية لتحسين كفاءتها كمثبطات للتآكل في مجموعة من البيئات الصناعية، خاصة بالنسبة للمعادن المعرضة للتآكل. أشارت النتائج إلى أن (ie%) وكانت المادة الكيميائية%90إلى %76تراوحت بين ، (a6) على السطح الفوالذي، وتكونت طبقات امتصاص وقائية %90هي األعلى قيمة وهي .وهي المسؤولة ألداء المانع الجيد mailto:khadija89najahz@gmail.com al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 6, no. 2, pp 5161 (2010) comparison of the rls and lms algorithms to remove power line interference noise from ecg signal noor k. muhsin department of biomedical engineering/ al-khwarizmi college of engineering/ baghdad university email: noorbmemsc81@yahoo.com (received 19 july 2009; accepted 31 march 2010) abstract biomedical signal such as ecg is extremely important in the diagnosis of patients and is commonly recorded with a noise. many different kinds of noise exist in biomedical environment such as power line interference noise (plin). adaptive filtering is selected to contend with these defects, the adaptive filters can adjust the filter coefficient with the given filter order. the objectives of this paper are: first an application of the least mean square (lms) algorithm, second is an application of the recursive least square (rls) algorithm to remove the plin. the lms and rls algorithms of the adaptive filter were proposed to adapt the filter order and the filter coefficients simultaneously, the performance of existing lms algorithm of the adaptive filters cause completely removing of the plin comparing with the rls algorithm that reducing the noise level only. keywords: filters, adaptive filters, lms algorithm, rls algorithm, power line interference noise, ecg signals. 1. introduction the most vital informative signals used to diagnose patients are the electrocardiogram (ecg), which is generated from heart activity. the ecg signal, measured with an electrocardiograph, is a biomedical electrical signal occurring on the surface of the body due to the contraction and relaxation of the heart. this signal represents an extremely important measure for doctors, as it provides vital information about a patient’s cardiac condition and general health [1]. generally, the frequency band of the ecg signal is 0.05 to 100hz, and the ecg signal includes 50hz power line interference noise[2]. 50hz power line noise can affect the qand pwaves of the ecg signal, generating errors during the diagnosis of arrhythmia or myocardial infarction. power line noise can cause errors by distorting the ecg signal during the measurement of the qrs complex interval or the qt interval, which are important parameters in diagnosis. in order to remove 50hz power line noise, an lms and rls adaptive filter can be applied by setting the notch filter of the 50hz band or the 50hzcomponent as a reference signal, so as to adjust the filter coefficient until the error is minimized from the input signal where the 50hz-component is included [3]. these biomedical signals vary in time and are nonlinear, so the least mean square (lms, rls) algorithms of the adaptive filter is mainly used. the lms, rls algorithms of the adaptive filter, however, removes noise or obtains the desired signal features by adapting the filter coefficients according to a given filter order; as a result, from time to time, the output error of the filter cannot be minimized in a noisy environment [4]. the algorithms of the adaptive filter were proposed to adapt the filter coefficients simultaneously, thus improving the performance of existing lms, rls algorithms of the adaptive filters in processing biomedical signals. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ noor k. muhsin al-khwarizmi engineering journal, vol. 6, no. 2, pp 51-61 (2010) 52 2. ecg signal, noise, and adaptive filtering electrocardiography (ecg) this is well known as ecg, which is used to measure the electrical activity of the heart. inside the heart there is a specialized electrical conducting system that ensures the heart to expand and contract (as a pump) this action is produced by a sinoatrial node (sa) located below the right atrium in the heart. sa node is called as pacemaker because it has the ability to initiate electrical pulses at a faster rate of 100 per minute [4]. figure1 clearly illustrates the sa & av nodes. fig. 1. electrical activity of heart [4]. four waves are detected while measuring the electrocardiography they are p, q, r, s and t waves as shown in figure 2. an impulse sent from a sa node starts the heart to beat, and then the electrical current will flow down to the lower chambers of the heart or atria and produce the p wave. then the electrical current will flow down to the lower chambers of the heart or ventricles producing the q, r and s wave. as the electrical current spreads back over the ventricles in the opposite direction it will produce the t waves [5]. if the rate of the heart is fast then the repolarization will be fast these results shorter the q-t interval. with slow heart rates, the q-t interval is longer. the q-t interval represents about 40% of the total time between the qrs complexes (the r-r interval). fig. 2. pqrst complex wave [5]. noise in ecg during the recording of any signal, it is inevitable that some undesirable signal loosely termed noise is also picked up such as (plin).[6] plin consists of 50 hz fundamental sinusoidal and its harmonics. this type of noise amplitude randomly modeled. the sampling frequency was 200 hz.[7]. adaptive filters the main purpose of this filter is to change (adapt) the coefficients of an fir filter to match as closely as possible to the response of an unknown system. the unknown system and the adapting filter process the same input signal and have the outputs. adaptive filters are self designing filters based on an algorithm which allows the filter to “learn” the initial input statistics and to track them if they are time varying. these filters estimate the deterministic signal and remove the noise uncorrelated with the deterministic signal [8]. the major advantage of these filters is they do not require prior knowledge of the signal or noise characteristics as it is used in normal filters. adaptive techniques is mainly used in filtering of 50hz line frequency from ecg signals, enhancing p waves and improves the time duration of qrs wave. 2.3.1. basic adaptive filter structure adaptive technique is widely used in eliminating noise interference.[8] the adaptive impulse correlated filter is considered which requires the primary signal this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ noor k. muhsin al-khwarizmi engineering journal, vol. 6, no. 2, pp 51-61 (2010) 53 and a reference signal as an input. in the signal enhancement application, the reference signal consists of a desired signal s(k) that is corrupted by an additive noise n(k). the input signal of the adaptive filter is a noise signal x(k) that is correlated with the interference signal n(k), but uncorrelated with s(k). figure 3 illustrate the configuration of the signal enhancement application[9]. fig. 3. noise cancellation [10]. 2.3.2. adaptive algorithms adaptive algorithms are used to adjust the coefficients of the digital filter such that the error signal, e(k), is minimized according to some criterion, for example the least squares sense. common algorithms that have found widespread application are the least mean square (lms), the recursive least squares (rls).[11] they gradually reduce the mean square error between the input signal and some reference signal. the main features that attach the use of the lms algorithm are low computational complexity, proof of convergence in stationary environment, unbiased convergence in the mean to the wiener solution, and stable behavior when implemented with finite_ precision arithmetic[11]. it does not suffer from the numerical instability problem inherent in other two algorithms. a ) lms algorithm the least mean square algorithm is used to adjust the weights of the adaptive filter in order to minimize the error and to estimate the deterministic component through filter output. this algorithm is well known and can be expressed by the following equation: )()(2)()1( kxkekwkw  …(1) where )(kw is the weight vector, and )(kx is the reference input and μ is the convergence factor, and )(ke is the error signal. the selection of the convergence factor μ becomes a trade off between convergence rate and the steady state mean square error. adaptive tapped-delay-line filter in this paper the method of least squares will be used to derive a recursive algorithm for automatically adjusting the coefficients of a tapped-delay-line filter (adaptive transversal), allow for elimination of noise while maintaining of optimal signal-to-noise ratio for nonstationary process,[blue book] as shown in figure 4, without invoking assumptions on the statistics of the input signals. this procedure, called the recursive leastsquares (rls) algorithm, is capable of realizing a rate of convergence that is much faster than the lms algorithm, because the rls algorithm utilizes all the information contained in the input data from the start of the adaptation up to the present. fig. 4. (tapped-delay-line filter) [9] 2.4.1. the deterministic normal equations the requirement is to design the filter in such a way that it minimizes the residual sum of squares of the error. …(2) the filter output is the convolution sum: …(3)    n i ienj 1 2 )()(    m k nikiunkhiy 1 ,...,2,1)1(),()( this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ noor k. muhsin al-khwarizmi engineering journal, vol. 6, no. 2, pp 51-61 (2010) 54 where h(k,n) is the filter weight, u(n) is the input vector which upon substituting becomes …(4) where ,e(n) the error of the filter, d(i) the desired signal, and y(n) the filter output. the deterministic correlation between the input signals at taps k and m, summed over the data length n, as ...(5) where ф(n) the deterministic correlation matrix of the tap input. we define the deterministic correlation between the desired response and the input signal at tap k, summed over the data length n, as …(6) θ(n) the deterministic cross-correlation vector we define the energy of the desired response as …(7) the residual sum of squares is now written as …(8) we may treat the tap coefficients as constants for the duration of the input data, from 1 to n. hence, differentiating eq. (8) with respect to h(k, n), we get …(9) let denote the value of the kth tap coefficient for which the derivative is zero at time n. thus, from eq. (9) we get …(10) this set of m simultaneous equations constitutes the deterministic normal equations whose solution determines the “least-squares filter”. vector form of the least-squares filter …(11) the deterministic correlation matrix of the tap inputs …(12) and the deterministic cross-correlation vector …(13) with these definitions the normal equations are expressed as …(14) assuming (n) is nonsingular …(15) and for the resulting filter the residual sum of squares attains the minimum value [12]: …(16) )()()( iyidie           n i m k m m n i n i m k miukiunmhnkh kiuidnkhidnj 11 1 11 1 2 )1()1(),(),( )1()(),(2)()( nm     n i mmkmiukiumkn 1 1,...,1,0,)()(),;(    n i mkkiuidkn 1 1,...,1,0)()();(    n i d idne 1 2 )()( )1,1;(),(),( )1;(),(2)()( 1 1 1        mknnmhnkh knnkhnenj m k m m m k d   mk mknnmhkn nkh nj m m 1,2,..., )1,1;(),(2)1;(2 ),( )( 1        ),(ˆ nkh ),()/( nkhnj  mkknmknnmh m m 1,2,...,)1;()1,1;(),(ˆ 1     tnmhnhnhn ),(ˆ),...,,2(ˆ),,1(ˆ)(ˆ h                     )1,1;(..)1,1;()0,1;( ..... ..... )1,1;(..)1,1;()0,1;( )1,0;(..)1,0;()0,0;( )( mmnmnmn mnnn mnnn n    φ  tmnnnn )1;(),...,1;(),0;()(  θ )()(ˆ)( nnn θh φ )()()(ˆ -1 nnn θh φ )()(ˆ)()(min nnnenj t d θh this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ noor k. muhsin al-khwarizmi engineering journal, vol. 6, no. 2, pp 51-61 (2010) 55 1,...,1,0, )()(),;1(),;(   mmk knumnumknmkn  1,...,1,0, )()(),;1(),;(   mmk knumnumknmkn  2.4.2. properties of the least-squares estimate 1. the least-squares estimate of the coefficient vector approaches the optimum wiener solution as the data length n approaches infinity, if the filter input and the desired response are jointly stationary ergodic processes. 2. the least-squares estimate of the coefficient vector is unbiased if the error signal e(i) has zero mean for all i. 3. the covariance matrix (is a measure of the linear coupling between two variables). to calculate the covariance matrix of the leastsquares estimate h^ equals ф-1, except for a scaling factor, if the error vector e0 has zero mean and its elements are uncorrelated. 4. if the elements of the error vector are statistically independent and gaussiandistributed, then the least-squares estimate is the same as the mmt maximum-likelihood estimate.[12] 2.4.3. the matrix-inversion lemma let a and b be two positive definite, m by m matrices related by …(17) where d is another positive definite, n by n matrix and c is an m by n matrix. according to the matrix-inversion lemma, we may express the inverse of the matrix a as follows: …(18) b ) the recursive least-squares (rls) algorithm the deterministic correlation matrix is now modified term by term as …(19) where c is a small positive constant and mk is the kronecker delta; …(20) this expression can be reformulated as …(21) where the first term equates yielding …(22) note that this recursive equation is independent of the arbitrarily small constant c. defining the m-by-1 tap input vector ….(23) we can express the correlation matrix as …(24) and make the following associations to use the matrix inversion lemma thus the inverse of the correlation matrix gets the following recursive form …(25) for convenience of computation, let …(26) and …(27) then, we may rewrite eq. (25) as follows: …(28) tccdba -1-1  )(nφ    n i mkckiumiumkn 1 )()(),;(        km km mk 0 1            1 1 )()()()(),;( n i mkckiumiuknumnumkn  ),;1( mkn  tm-nu-nunun 1)(1),...,(),()( u )()()()( nnnn tuuφφ  1)( 1)()( -1   duc ba n -nn φφ )(1)()(1 1)()()(1)( 1)()( 1-1-1 1-1n-nn -nnn-n --nn t t uu uu φ φφ φφ   )()( -1 nn φp )(1)()(1 )(1)( )( n-nn n-n n t upu up k   1)()()(-1)()( -nnn-nn t pukpp    bcbccdbc-ba tt -11 this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ noor k. muhsin al-khwarizmi engineering journal, vol. 6, no. 2, pp 51-61 (2010) 56 the m-by-1 vector k(n) is called the gain vector. postmultiplying both sides of eq.(28) by the tap-input vector u(n) we get …(29) rearranging eq. (27) we find that …(30) therefor substituting eq. (30) in eq. (29) and simplifying we get …(31) reminding that the recursion requires not only updates for as given by eq. (28) but also recursive updates for the deterministic cross-correlation defined by equation (6) which can be rewritten as …(32) yielding the recursion …(33) as a result …(34) with the suitable substitutions we get …(35) which can be expressed as …(36) where (n) is a “true” estimation error defined as …(37) equations (36) and (37) constitute the recursive least-squares (rls) algorithm.[12] 3. methodology to verify the algorithms suggested in this paper, the normal ecg signal (down loaded from internet ftp://ftp.ieee.org/uploads/press/rangayyan/). was added to the plin (plin consists of 50 hz fundamental sinusoidal and its harmonics, this type of noise amplitude randomly modeled. the sampling frequency was 200 hz.[1,2]) then filtered the noisy ecg signals and evaluated the overall error of the signal and the optimal filter order. in this experiment, matlab package (version 8) was used in writing the programming code of the proposed system and estimate the performance of the adaptive filter, the noisy ecg signal was filtered with two algorithms as shown in the block diagram. fig. 5. block diagram of the proposed system. the parameters of the implemented algorithms are as follows: a ) lms algorithm a notch adaptive filter was used with the aid of the below lms algorithm specifications: order of the fir filter: 2nd stability factor or step size parameter (μ), is a convergence factor that controls stability as well as the rate of adaptation, μ=.9 was selected to produce the best adaptation results. initial weight vector: 0 b ) rls algorithm rls algorithm specifications: order of the fir filter: 5th λ=0.999 initial weight vector: 0 )(1)()()(-)(1)()()( n-nnnn-nnn t upukupup  )()(1)()(1)()()( n-n-nn-nnn t kupupuk  )()()( nnn upk  )()()(ˆ -1 nnn θh φ )()(-1 nn pφ );1()()( )()()()();( 1 1 knknund kiuidknundkn n i        )()()1()( nndnn uθθ    )()()1()( )()()()1()( )()()1()()()()(ˆ ndnnn ndnnnn ndnnnnnn kθp upθp uθpθph    )1(ˆ)()()(  nnndn t hu    )1()1()()()()1()1( )()()1()1()()()1()(ˆ   nnnndnnn ndnnnnnnn t t θpukθp kθpukph   )()()1(ˆ )1(ˆ)()()()1(ˆ)(ˆ nnn nnndnnn t kh hukhh   this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ noor k. muhsin al-khwarizmi engineering journal, vol. 6, no. 2, pp 51-61 (2010) 57 the reference signal of the adaptive filter used these noise signals with sampling frequency of the input and the reference signals are 200hz. fig.6. multidimensional signal-flow graph (a) rls algorithm (b) lms algorithm [12]. 4. results the filtered results (the outputs of the adaptive filter) are shown in figures (7-14), where the filter order is converged to minimize the distortion of ecg signal. by calculating the maximum, minimum, mean and standard deviation for both output curves and errors curves using matlab programs where (max: largest elements, min: smallest elements, mean: the average value of a signal. it is found by adding all of the samples together, and divide by n. it looks like this in mathematical     1 0 1 n i ixn mean in words, sum the values in the signal, x , by letting the index, i, run from 0 to n-1. then finish the calculation by dividing the sum by n.[13] std: standard deviation the standard deviation s of a data vector x: 2/1 1 2 1                  n i i x n std x where     n i ixn x 1 1 and is the n number of elements in the sample. the two forms of the equation differ only in n-1 versus n in the divisor. the results are shown in the following table: table 1, the results of the adaptive filter output(lms) error(lms) max1 3.0774 3.8246 min1 -1.1664 -1.9172 mean1 0.0872 0.0996 std1 0.4819 0.8577 output(rls) error(rls) max2 2.8932 2.1723 min2 -2.5815 -1.9836 mean2 -0.1137 -0.0027 std2 0.9287 0.3605 from the above tables to compare between the standard deviation of the (lms algorithm) output and the (rls algorithm) output the result shown that (std1<std2) that mean deviation of the results from the true curve is smaller in case of lms than the rls. the proposed lms adaptive filter: figures 7, 8 shows normal ecg and noisy ecg respectively. figures 9, 10 and 11 show the experimental results of the lms adaptive filter’s filter of 2 nd order; after convergence and filtering, the noisy ecg signal was filtered by completely removing to the plin as shown in figure 8 with minimum error as shown in figure 9. the proposed rls adaptive filter: figures 12, 13 and 14 shows experimental results of the rls adaptive filter of 5 th order; after convergence and filtering, the output results of the filtration process were reduced the plin as shown in figure 12, and more pleasant in the fourier transform results in figure 13 with minimum error as shown in figure 14. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ noor k. muhsin al-khwarizmi engineering journal, vol. 6, no. 2, pp 51-61 (2010) 58 0 0.5 1 1.5 2 2.5 -5 0 5 ( a ) a m p .( v ) 50 100 150 200 250 300 350 400 450 0 1 2 ( b ) a m p .( v ) 0 20 40 60 80 100 120 140 160 180 200 -5 0 5 ( c ) a m p .( v ) 0 10 20 30 40 50 60 70 80 90 100 0 10 20 ( d ) x ( k ) time(sec) sample no. sample no. ferq.(hz) 0 20 40 60 80 100 120 140 160 180 200 -1 0 1 ( a ) a m p .( v ) 0 20 40 60 80 100 120 140 160 180 200 -2 0 2 4 ( b ) a m p .( v ) 0 10 20 30 40 50 60 70 80 90 100 0 20 40 60 80 freq.(hz)( c ) x ( k ) time(msec) sample no. fig.7. normal ecg signals, (a) normal ecg signal, (b) sampled ecg signal, (c) one period ecg signal (d) amplitude spectrum of the normal ecg signal. fig.8. plin and its effects on the ecg signal, (a) plin, (b) ecg + plin, (c) amplitude spectrum of the (ecg+plin). fig.9. output of the general lms adaptive filter. fig.10. ft (output of the general lms adaptive filter, noisy ecg signal and normal ecg). fig.11. output error of the general lms adaptive filter. fig. 12. output of the general rls adaptive filter. 0 20 40 60 80 100 120 140 160 180 200 -2 -1 0 1 2 3 4 5 system output samples th e pr im ar y an d ou tp ut s ig na ls 0 20 40 60 80 100 120 140 160 180 200 0 5 10 15 20 25 30 35 40 45 50 freq. (hz) x( k) ft(output of the filter) ft(noisy ecg) ft(normal ecg) 0 20 40 60 80 100 120 140 160 180 200 10 -4 10 -3 10 -2 10 -1 10 0 10 1 error curve samples e rro r v al ue 0 20 40 60 80 100 120 140 160 180 200 -3 -2 -1 0 1 2 3 samples t ru e an d es tim at ed o ut pu t system output d= firsampledata y=output of filter this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ noor k. muhsin al-khwarizmi engineering journal, vol. 6, no. 2, pp 51-61 (2010) 59 fig. 13. ft( output of the general rls adaptive filter and noisy ecg signal). fig.14. output error of the general rls adaptive filter. 5. conclusions biomedical signals play a crucial role in the diagnosis of patients. two algorithms for the adaptive filters the lms and rls algorithms were suggested, as signal changes in time and can be variously mixed with noise depending on the environment and based on the patient’s condition. excessive filtering results in a distorted signal. to verify performance, the plin was selected to add to the ecg signal and evaluated the performance of these two algorithms. the lms adaptive filter is widely used to filter the ecg signal, with better performance in the experiment but the existing rls algorithm adapt to the environment showing limitations in the given filter, so its convergence and performance cause poor performance, depending on the environment and the patient’s condition. in the lms algorithm, the correction that is applied in updating the old estimate of the coefficient vector is based on the instantaneous sample value of the tap-input vector and the error signal. on the other hand, in the rls algorithm the computation of this correction utilizes all the past available information. in the lms algorithms, the correction applied to the previous estimate consists of the product of three factors: the (scalar) step-size parameter , the error signal e( n-1), and the tap-input vector u(n-1). on the other hand, in the rls algorithm this correction consists of the product of two factors: the true estimation error (n) and the gain vector k(n). the gain vector itself consists of 1(n), the inverse of the deterministic correlation matrix, multiplied by the tap-input vector u(n). the major difference between the lms and rls algorithms is therefore the presence of -1(n) in the correction term of the rls algorithm that has the effect of decorrelating the successive tap inputs, thereby making the rls algorithm selforthogonalizing. because of this property, we find that the rls algorithm is essentially independent of the eigenvalue spread of the correlation matrix of the filter input. unlike the lms algorithm, there are no approximations made in the derivation of the rls algorithm. accordingly, as the number of iterations approaches infinity, the least-squares estimate of the coefficient vector approaches the optimum wiener value, and correspondingly, the mean-square error approaches the minimum value possible. in other words, the rls algorithm, in theory, exhibits zero misadjustment. on the other hand, the lms algorithm always exhibits a nonzero misadjustment; however, this misadjustment may be made arbitrarily small by using a sufficiently small step-size parameter . notation j(k) the residual sum y(i) the filter output x(k) the filter input x the data vector h(k,n) the filter weight e(n),e(k) the error of the filter n(k) the reference signal ii index values n number of elements in the sample s(k) the desired signal u(n) the input vector 0 20 40 60 80 100 120 140 160 180 200 0 5 10 15 20 25 30 35 40 45 freq. (hz) x( k) ft(output of the filter) ft(noisy ecg) ft(normal ecg) 0 20 40 60 80 100 120 140 160 180 200 10 -3 10 -2 10 -1 10 0 10 1 error curve samples e rro r v al ue this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ noor k. muhsin al-khwarizmi engineering journal, vol. 6, no. 2, pp 51-61 (2010) 60 w(k the filter weight m number taps coefficients n total number of samples std standard deviation d(i) the desired signal ed the energy of the desired response d(i) the desired signal e0 error vector p(n) convergence of computation k(n) the gain vector a, b, c, d positive matrices p,q,r,s,t ecg components greek letters µ step-size paramerter ĥ(n) vector form of the least-squares filter ф(n) the deterministic correlation matrix of the tap input θ(n) the deterministic cross-correlation vector ζ(n) the true estimation error δmk the kronecker delta ф(n;k,m) the deterministic matrix between the input signal at taps k and m over the summed θ(n) the deterministic correlation between the desired response and the input signal at tap k sum over the data length n ф-1(n) the correlation terms of the rls algorithm λ forgetting factor 6. references [1] r. aston, principles of biomedical instrumentation and measurement, merrill publishing, pp. 37-255, 1990. [2] j. j. carr and j. m. brown, introduction to biomedical equipment technology, prentice hall, pp. 168-389, 1997. [3] j. s. sahambi, s. n. tandon, and r. k. p. bhatt, “wavelet based st-segment analysis,” med.biol. eng. & comput., vol. 36, no. 5, pp. 568572, september 1998. [4] the ‘nursing standard’the uk’s best selling nursing journal. rcn publishing 2005. from the archives of the journal, quick reference guide 4 electrocardiography. http://www.nursingstandard. co.uk/archives/ns/residentpdfs/quickrefpdffi les/quickref4.pdf [5] ‘essortment'the online website about the information you want to know. in 2005 pagewiseinc, southih-35, steq-11round rock, tx 78681. http://nh.essortment.com/whatiselectrc_okr.ht m [6] kamaran jamshaid, omar akram, farooq sabir, dr. ismail shah, and dr. jamil ahmed, “application of adaptive and non adaptive filters in ecg signal processing”, ieee transactions on biomedical engineering , vol. 39, october, 1992. [7] hrishikesh gokhale, “biomedical digital signal processing” ,1995 http://www.ebar.dtu.dk/ http://homepages.enterprise.net/djenkins/ecgh ome.html [8] application of adaptive and non adaptive filters in ecg signal processing by kamrun jamshaid, omar akram, farooq sabir, dr.syed ismail shah, faculty of electronic engineering, dr. jamil ahmed, faculty of computer science and engineering, gik institute of engineering sciences and technology (1999). [9] paulo s.r. diniz, “adaptive filtering algoriyhms and practical implementation”, copyright © 2002 by kluwer academic publishers, 2002. [10] elanix, “adaptive digital signal processing”, http://www.entegra.co.uk [11] david j. defatta, joseph g. lucas, and william s. hodgkiss, “digital signal processing: a system design approach”, copyright © 1988 by john wiley and sons, inc., 1988. [12] [12]http://www.it.lut.fi/mat/kesakoulu/yorg on_kalvot/adaptive_filtering_chapter4.ppt# 256,1,slide 1 [13] steven w. smith, "the scientist and engineer's guide to digital signal proceesing" this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ )2010( 61-51 ، صفحة2، العدد 6مجلة الخوارزمي الھندسیة المجلد نور كمال محسن 61 )تكرار اقل تربیع( خوارزمیةو ) اقل معدل تربیع(خوارزمیة المقارنھ بین ضوضاء قدرة الخط ألتداخلي من اشارة تخطیط القلب الزالة نور كمال محسن جامعة بغداد/ كلیة الھندسھ الخوارزمي /قسم ھندسة الطب الحیاتي noorbmemsc81@yahoo.com : البرید االلكتروني الخالصھ اء االشارات الطبیھ مثل اشار جل . ة تخطیط القلب مھمھ جدا في تشخیص المرضى و عادة تسجل معھا ضوض ي تس اء الت واع الضوض ن ان ر م اك الكثی ھن ل ھ مث ھ الطبی داخلي في البیئ ط ألت درة الخ اء ق حات المت . ضوض امالت المرش ر مع ا تغیی ھ بامكانھ حات المتكیف وب، المرش ذه العی ى ھ ب عل رت للتغل ھ اختی كیف ق ، )اقل معدل تربیع(خوارزمیة المھمھ االولى في ھذا البحث ھو تطبیق . بة المرشحالمرشح مع اعطاء رت و تطبی ث ھ ذا البح ي ھ ھ ف ة المھمھ الثانی خوارزمی ع ( خوارزمیة .ضوضاء قدرة الخط ألتداخليالزالة )تكرار اقل تربیع( دل تربی ة و )اقل مع ع ( خوارزمی ل تربی رار اق ى )تك رت لتھ ھ اختی حات المتكیف ء للمرش ة ) اقل معدل تربیع(اداء خوارزمیة . رتبة المرشح و عواملھ بشكل متزامن ة بخوارزمی ا مقارن داخلي نھائی ل (تؤدي الى ازالة ضوضاء قدرة الخط ألت رار اق تك . التي تؤدي الى تقلیل مستواه فقط )تربیع this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ <4d6963726f736f667420576f7264202d20e3e5c720e6c7d3d1c7c120e6d3caed20e6e4e6d120e6d3e1e6ec31362d3235> this is an open access article under the cc by license : al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 18, no. 1, marh, (2022) p. p. 1625 effect of mass ratio on phytoremediation of nickel contaminated water maha taha* israa abdulwahab al-baldawi ** siti rozaimah sheikh abdullah*** nur ’izzati ismail**** salwa shamran jasim***** *,**,*****department of biochemical engineering/ al-khwarizmi college of engineering/ university of baghdad, baghdad/ iraq. ***,****department of chemical and process engineering, faculty of engineering and built environment/ universiti kebangsaan malaysia/ malaysia *email: mahairaq700@gmail.com **email: israa@kecbu.uobaghdad.edu.iq ***email: rozaimah@ukm.edu.my ****email: nurezatyismail@ukm.edu *****email: salwa.shamran@gmail.com )2022 february 23 2021; accepted august 30received ( https://doi.org/10.22153/kej.2022.02.001 abstract water pollution is one of the global challenges that the society must address in the 21st century aiming to improve the water quality, reduce human pollutants and ecosystem health impacts. in phytotoxicity test, the plant of iresine herbstii was exposed to remove nickel from simulated wastewater using two different ratios (mass of plant to the mass of nickel) (,rp/ni) for 21 days with sub-surface batch system. during the exposure period, the removal of ni concentrations (2, 5 and 10 mg/l) for two mass ratio (2,800 and 34,000) were (83.6%, 77.2%, 78.0%) and (86.8%, 97% and 95.6%), respectively. final result of the rate was found that the highest removal occurred, 97%, at a mass ratio of 34,000 and a nickel concentration of 5 mg/l. metal accumulation mechanism of plants were examined using bioconcentration factor (bcf) and translocation factor (tf) of metals which indicated that i. herbstii is suitable for phytostabilization of ni (bcf>1 and tf<1). therefore, the ability of i. herbstii to treat wastewater contaminated with nickel that i. herbstii is considered a potential plant to remove ni from contaminated water. keywords: iresine herbstii, nickel removal, mass ratio, ornamental plant, phytoremediation. 1. introduction recently, solid and water wastes treatment are taking huge attention due to the higher generation of this wastes by industrialization and urbanization every year, which creates a big environmental problems worldwide [1]. excessive or improper use of synthetic chemical compounds due to anthropogenic activities which have highly affected on the environment and threatened human health (toxicity and carcinogenicity) [2]. heavy metals, organic solvents, and hydrocarbons are among the major threat to land, air, and water [3]. heavy metal bearing waters are considered a major environmental burden. they are posing risk to the ecological systems and human health even at low concentrations, since heavy metals are accumulative and non-biodegradable [4]. heavy metals usually enter the environment either naturally through weathering of parent materials, or man-made through metals extraction from ores followed by subsequent processing for further use in numerous applications, and the discharge of high concentration metal waste by industries [5]. nickel is a global trace element and the commonest metal that cause metal allergy among maha taha al-khwarizmi engineering journal, vol. 18, no. 1, p.p. 1625 (2022) 17 the people. nickel allergy is a chronic, recurring problem; females are affected more commonly than males [6]. water contaminated with nickel is from industries such as printing, electroplating, battery manufacturing industries, nickel refineries, and electronic products [7]. constructed wetlands (cws) can be an acceptable environmental option in domestic wastewater treatment. but this technology and its implementation in decentralization practices is still under discussion [8]. cws have been commonly used in water treatment systems as substitute for conventional methods because of their low energy requirements as well as easy operation and maintenance [9]. man-made systems have been design to drop the principle of natural wetlands for treating wastewater [1]. they are used widely as an inexpensive and easy to implement for treating wastewater from different sources [10]. it has been proven that plants have the ability to extract heavy metals from contaminated area [11,12]. the present study was carried out to examine which of the two different mass ratio (rp/ni) is the best ratio to remove nickel (ni) from the sub-surface batch system. consequently, the outcomes of this research are useful for selecting the appropriate mass ratio to reach efficient management site of phytoremediation via cw for any known wastewater pollutant concentration thus calculate the amount of plant required. as well as the objectives of the study is to investigate the ability of iresine herbstii to grow and survive in wastewater contaminated with nickel, in order to identify the best removal based on plant to metal mass ratio and finally to determine the mechanisms involved in the removal of heavy metals. 2. materials and methods 2.1 experimental set-up the study was done in an open environmental area at al-khwarizmi college of engineering, university of baghdad. this study, nine aquariums made of glasses, each one with dimensions of 30×30×30 cm (length ×width ×depth) with subsurface batch system (ssb), were used as shown in figure 1. in sub-surface batch (ssb) system, each aquarium was filled with large coarse gravel (φ = 5-3 cm) with 10 cm depth followed by 10 cm fine gravel (φ 1–2 cm). the water level was maintained within the fine gravel layer in order to simulate a sub-surface system as used in real wetlands. for this system, three aquariums for each minimum and maximum mass ratio (rp/ni) were used. two mass ratio (rp/ni) factors of 2,800 and 34,000 were selected as the minimum and maximum values, respectively, according to beaker's preliminary test optimization. the other three aquariums acted as control contaminant without plants. contaminated water of 5 l for each aquarium was prepared by mixing water with nickel to form different concentrations (2, 5, and 10 mg/l). the water level was kept within the gravel layer surface (up to 21 cm height of the aquarium) to simulate sub-surface batch system. fig. 1. plants arrangement in the aquarium according to the mass ratio. maha taha al-khwarizmi engineering journal, vol. 18, no. 1, p.p. 1625 (2022) 18 table 1 shows the details of plant mass added to each aquarium for two mass ratios of 2,800 and 34,000 which were calculated according to the equation (1): ( ) p p/ni ni ww ww m mass ratio r m mass of plant(g) = ni (g / l) v (l) = × … (1) where, mp is the mass of plant in (g), mni is the mass of nickel in (g/l), niww is the concentration of nickel in wastewater in (g/l) vww is the volume of wastewater in (l), table 1, plant mass planted in each aquarium with respect to ni concentration 2.2 physical parameters monitoring during 21 days of experimental work, samples were taken from taps in each aquarium (figure 2) at days 0, 7, 16, and 21. the physic-chemical changes in a water samples from each aquarium were recorded. the parameters of temperature t (°c), ph, and total dissolved solid (tds, mg/l) were measured by iso lab (3110germany) probe. dissolved oxygen (do, mg/l) was recorded by hach (hq430d, usa) probe. mass ratio = 34,000 mass ratio = 2,800 mass ratio = 0 fig. 2. sub-surface batch system (ssb) mass ratio minimum = 2,800 maximum = 34,000 ni concentration (mg/l) plant mass (g) 2 5 10 2 5 10 28 70 140 340 850 1,700 maha taha al-khwarizmi engineering journal, vol. 18, no. 1, p.p. 1625 (2022) 19 2.3 analysis of ni in effluent water sample of 20 ml was collected from each aquarium on each sampling day (0, 7, 16, and 21) and stored it in clean tubes. the ni analysis was done in the medium of water by using a atomic a absorption device (model aa-7000, shimadzu, japan) at iraq ministry of science and technology. the ni removal efficiency from water sample was determined by using equation (2): ( ) 0 t 0 ni ni ni c c nickel removal % 100 c  − = ×      …(2) where cni0 is the ni concentration at time 0 (mg/l), cnit is the ni concentration at sampling time (mg/l). 2.4 ni extraction in plant and bioconcentration factor the extraction process was carried out on aquariums with a mass ratio of 2,800 because the plant remained semi-healthy. one plant i. herbstii was harvested from each aquarium with different concentrations (2, 5, and 10 mg/l) of ni. plant was first washed with tap water, and then stem and roots parts were separated to dry in oven with temperature at 70℃. an amount of 5 g was accurately weighed for each of the stem and roots. the plant samples were mineralized to determine ni content according to turek et al., (2019) method [13]. finally, ni extraction from i. herbstii stem and roots were determined by atomic absorption device as explained in section 2.3. bio-concentration factor (bcf) of plants is the most important botanical feature in the phytoremediation process. it gives an idea about the uptake potential for the metals, their mobilization into plant tissues, and storage in the aerial plant biomass [14]. bcf in stem and roots during day 21 was calculated for each ni concentrations (2, 5, 10 mg/l). the bcf was estimated as the ratio of the metal concentration in the plant (mg kg-1 of dry weight) to the metal concentration in the growth medium (mg l-1) [15], according to based on the following equation (3) [16]. ni plant ni water c bcf c = … (3) where, cni plant is the concentration of nickel in the plant (mg/g), cni water is the concentration of nickel in water (mg/l). translocation factor (tf) is calculated to know the ability of plant to translocate metal from media by roots to shoots. tf is computed by dividing the ni concentration in the plant's stem over ni concentration in the plant's root (mg g-1 of dry weight) as shown in equation (4) [15]. ni stem ni root c tf= c …(4) where, cni stem is the ni concentration in stem (mg/g), cni root is the ni concentration in the root (mg/g). if both bcf and tf are >1, it thus indicates the appropriateness of plants for phytoextraction mechanism; but, high bcf>1 and low tf<1 indicates appropriateness for phytostabilization mechanism [17]. 3. results and discussions 3.1 observation of physical parameters during 21 days of phytotoxicity test, the selected physicochemical parameter was measured for aquarium with different mass ratio (0, 2,800 and 34,000) as shown in table 2. generally, the temperature increased in the test period depending on weather and varied from 19.932.3ᵒc for all treatments. the optimum temperature for plants growth and accumulation of heavy metal did not exceed 32.2˚c [18]. the ph for aquariums was ranged between 7.14 to 8.10 and 7.38 to 7.72 for aquariums with plants and without plants, respectively. according to rana and maiti 2018 [17], the neutral to slightly alkaline environment implies that metal immobilization in the plant rhizosphere and absorption through plant roots are two plausible routes for metal elimination [17]. the do was ranged between 0.96 to 4.98 mg/l and 3.40 to 6.77 mg/l for treatment with plants and without plants, respectively. it is clearly demonstrated that treatment with plants was leading to reduce the do in the water media, may be due to rhizosphere zone (plant-bacteria interaction) [19]. tds are the measurement of inorganic salts in wastewater, which ranged between 122.10 to 255.00 mg/l for all treatment. the concentration of tds was inconsistent from day to day because the system was not fully acclimatized. the depletion of oxygen in the water system is characterized by high nutrient content and low dissolved oxygen, which indicates that the aquatic organism is decomposing [20]. maha taha al-khwarizmi engineering journal, vol. 18, no. 1, p.p. 1625 (2022) 20 table 2, variation of physical parameters in phytotoxicity test in ssb system n i = 2 m g /l parameter mass ratio 0 mass ratio 2,800 mass ratio 34,000 t (°c) 24.15-26.65 24.15-26.55 26.80-29.90 ph 7.38-7.70 7.6-7.60 7.68-8.75 do (mg/l) 4.30-3.98 4.40-2.40 4.80-2.54 tds (mg/l) 122.10-242.50 133.75-235 135.45-255 n i = 5 m g /l t (°c) 24.15-26.65 24.05-26.25 28.10-27.30 ph 7.55-7.69 7.14-7.76 7.52-8.10 do (mg/l) 4.36-3.46 4.30-1.84 4.61-2.23 tds (mg/l) 127.15-235.00 126.15-235 125.20-236.00 n i = 1 0 m g /l t (°c) 24.20-26.75 24.15-26.15 26.55-28.30 ph 7.68-7.72 7.26-7.77 7.64-8.64 do (mg/l) 4.59-3.52 4.58-0.95 4.98-2.22 tds (mg/l) 120.20-235.00 133.55-231.50 134.24-233.80 3.2 ni removal from water in sub-surface batch system (ssb) the concentrations of ni using three mass ratios (0, 2,800, and 34,000) during experiment period are shown in figure 3. the decreasing in ni concentrations were 1.9-1.7, 1.9-0.31 and 1.9-0.25 mg/l; 4.7-4.1, 4.7-1.07 and 4.7-0.14 mg/l; and 9.3-0.6, 9.3-2.04 and 9.3-0.4 mg/l, for ni concentrations (2, 5, and 10 mg/l) to each mass ratio 0, 2,800, and 34,000, respectively. the reduction of ni concentration were due to several reasons including phytoremediation mechanisms (phytodegradation, phytoextraction, phytostabilization) [21] and physical mechanisms (adsorption, precipitating) [22]. ni removal percentages were calculated for each week within different mass ratios (0, 2,800, 34,000) and three concentrations throughout 21 days. for the mass ratio of 0, the removal rate was low because there was no plant in the aquarium. for the mass ratio of 2,800, the removal was 31-83.6%, 35.7-77.2%, and 25.9-78.0% for ni concentrations of 2, 5, and 10 mg/l, respectively. the mass ratio of 34,000, the removal ranged between 45.7-86.8%, 35.997%, and 34.4-95.6% for ni concentrations 2, 5, and 10 mg/l, respectively. from the obtained results as a result of the removal rates of the three mass ratios (0, 2,800, 34,000) it was found that the highest removal occurred at the mass ratio of 34,000 and ni concentration of 5 mg/l which was 97.0% on day 21. these results declare the capability of i. herbstii to enhance and accelerate the removal of heavy metal from contaminated water. a previous study by pandey et al. 2007 [23], stated the ability of plant (calotropis procera) to remove 250 mg/l ni pollutants with 85% sorption efficiency from aqueous solution. in an earlier research,by alyazouri et al. 2014 [24], they was exceeded 90% for 5.1 mg/l ni concentration in wetland which provide long term treatment. the removal of ni in the aquarium without plant (cc) is due to the biological, physical, and chemical processes that occurred within substrate media[23]. maha taha al-khwarizmi engineering journal, vol. 18, no. 1, p.p. 1625 (2022) 21 fig. 3. ni concentrations and removal percentage by iresine herbstii during 21 day and mass ratio (0, 2800, 34000) (a) 2 mg/l, (b) 5 mg/l and (c) 10 mg/l 0 10 20 30 40 50 60 70 80 90 100 0 1 2 3 4 5 6 7 8 9 10 11 12 d ay 0 d ay 7 d ay 1 6 d ay 2 1 d ay 0 d ay 7 d ay 1 6 d ay 2 1 d ay 0 d ay 7 d ay 1 6 d ay 2 1 0 mass ratio 2800 mass ratio 34000 mass ratio n i r e m o v a l % n i c o n c e n tr a ti o n ( m g /l ) ni concentration (mg/l) ni removal %(a) 0 10 20 30 40 50 60 70 80 90 100 0 1 2 3 4 5 6 7 8 9 10 11 12 d ay 0 d ay 7 d ay 1 6 d ay 2 1 d ay 0 d ay 7 d ay 1 6 d ay 2 1 d ay 0 d ay 7 d ay 1 6 d ay 2 1 0 mass ratio 2800 mass ratio 34000 mass ratio n i r e m o v a l % n i c o n c e n tr a ti o n ( m g /l ) ni concentration (mg/l) ni removal %(b) 0 10 20 30 40 50 60 70 80 90 100 0 1 2 3 4 5 6 7 8 9 10 11 12 d ay 0 d ay 7 d ay 1 6 d ay 2 1 d ay 0 d ay 7 d ay 1 6 d ay 2 1 d ay 0 d ay 7 d ay 1 6 d ay 2 1 0 mass ratio 2800 mass ratio 34000 mass ratio n i r e m o v a l % n i c o n ce n tr a ti o n ( m g /l ) ni concentration (mg/l) ni removal %(c) maha taha al-khwarizmi engineering journal, vol. 18, no. 1, p.p. 1625 (2022) 22 3.3 accumulation of ni in iresine herbstii after the digestion process, ni accumulation in plant stems and roots, using three different ni concentrations, are displayed in figure 4. the highest accumulations of nickel were 48.99 mg/g and 12.89 mg/g in the root and stem of i. herbstii at 10 mg/l ni concentration, respectively. according to alyazouri et al. [25], the phrase "hyper accumulator" was coined to describe the tree of sebertia acuminates accumulation of ni in dry leaf tissue at levels greater than 1000 mg/kg. while based on aran et al. [15], during 28 days of exposure, ni accumulation in leaves and roots of large floating plants grew significantly by increasing exposion's time and metal concentration for various treatments. to table 3 presents the almost bcf>1 and tf<1 which indicating that the potential of i. herbstii roots to absorb ni through phytostabilization of ni pollutants [26]. fig. 4. nickel in iresine herbstii. table 3, bcf and tf of ni in the iresine herbstii after 21 days of exposure 4. conclusion the current study reports successful green technology by using renewable natural materials, which are eco-friendly and cheap. the study of the phytoremediation using iresine herbstii was successfully conducted to remediate contaminated water with ni. the highest removal during the 21day exposure was 97.0% and 95.6% for mass ratios of 3,400 for ni concentrations of 5 and 10 mg/l, respectively. therefore, from the results, it can be concluded that the removal efficiency with a mass ratio of 34,000 is greater than the mass ratio of 2,800. moreover, the bcf values of i. herbstii roots were higher than 1, ranging from 4.89 to 6.52 thus is considered a which a good accumulator and suitable for both phytoextraction and phytostabilization., this study proves that the possibility of using i. herbstii to ni phytoremediation of from industry wastewater due to their availability and low cost for treatment. acknowledgements the authors would like to express our gratitude to the college of engineering and the alkhwarizmi college of engineering, university of baghdad, and the iraqi ministry of higher education for supporting this research project. we also express our gratitude to universiti kebangsaan 0 10 20 30 40 50 60 steam mg g-1 root mg g-1 n i c o n te n t in i r e si n e h e rb st ii ( m g /g ) 2mg/l 5mg/l 10mg/l ni concentration (mg/l) bcf in stem bcf in root tf 2 mg/l 4.224 5.129 0.823 5 mg/l 0.750 6.521 0.115 10 mg/l 1.289 4.899 0.263 maha taha al-khwarizmi engineering journal, vol. 18, no. 1, p.p. 1625 (2022) 23 malaysia for the research collaboration through dcp-2018-006/3 grant. 5. reference [1] i. a. al-baldawi, a.a. mohammed, z. h. matur, s. r. sheikh abdullah, s. s. jasim, a. f. almansoory, n. i. ismail, “application of phytotechnology in alleviating pharmaceuticals and personal care products (ppcps) in wastewater: source, impacts, treatment, mechanisms, fate, and swot analysis,” j. clean. prod., vol. 319, pp 128584, 2021. 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[24] a. alyazouri, r. jewsbury, h. tayim, p. humphreys, m. h. al-sayah, “applicability of heavy-metal phytoextraction in united arab emirates: an investigation of candidate species,” soil sediment contam., vol. 23, pp. 557–570, 2014. ) 2022( 1625، صفحة 1العدد، 18مجلة الخوارزمي الهندسية المجلد ابراهيم ه مها ط 25 تأثير نسبة الكتلة على المعالجة النباتية للمياه الملوثة بالنيكل **الوهاب البلداوي أسراء عبد* مها طه أبراهيم ***هللا سيتي رزيمه الشيخ عبد *****سلوى شمران جاسم **** نور عزاتي أسماعيل العراق / كلية الهندسة الخوارزمي/ جامعة بغداد / قسم الهندسة الكيميائية االحيائية *،**،***** قسم الهندسة الكيميائية والعمليات/ كلية الهندسة المدنية والبيئة/ جامعة كيبانغسان ماليزيا/ ماليزيا ****،*** mahairaq700@gmail.com: البريد االلكتروني * :israa@kecbu.uobaghdad.edu.iq البريد االلكتروني ** :rozaimah@ukm.edu.my االلكترونيالبريد *** :nurezatyismail@ukm.eduالبريد االلكتروني**** :salwa.shamran@gmail.comالبريد االلكتروني***** الخالصة من خالل تعريض نبات دم ة النباتي ة السمي اختبارتم في هذه الدراسة .المستدامة التكنولوجية الخضراء ضمن البيئة أحد استخدام النبات بمعالجة المياه هو السطح.يوم في نظام دفعات تحت ٢١ ة) لمدp/nir( مختلفةنبات بعنصر النيكل بنسب كتل الملوثةمن المياه ةالمعادن الثقيل ةإلزال ) irasen herbstiiالعاشق ( ,%86.8)و (%78 ,%77.2 ,%83.6 ٢٨٠٠٬٣٤٠٠٠لتر) ونسب الكتل للنبات /ملجم ٢٬٥٬١٠( المختلفةالنيكل لتراكيز ة األزالخالل فتره التعرض كانت ٣٤٠٠٠للنبات ةالتي تم الحصول عليها من خالل الشرح أعاله وجد أنه اعلى أزاله كانت عند نسبه الكتل ةالنهائي ة للنتيج ة على التوالي . بالنسب (95.6% ,97% ) tf) وعامل االنتقال ( bcfتم فحص آلية تراكم المعادن للنباتات باستخدام عامل التركيز األحيائي ( .٢١) عند اليوم ٩٧التي كانت (%لتر و/ملجم ٥ وتركيز كان لديه القدرة على معالجة مياه الصرف السبب،لهذا ). tf < 1 و bcf > 1للمعادن التي أشارت إلى أن نبات اإليريسين مناسب للتثبيت النباتي للنيكل ( من المياه الملوثة. niهو نبات محتمل إلزالة iresine herbstiiالصحي الملوثة بالمعادن الثقيلة مما يدل على أن this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 20, no. 1, march, (2024), p p. 5162 karnaugh maps adaptability to implement multiple-actuator pneumatic circuits alzahraa nather* maher yahya salloom** amir azizi*** sahala siallagan**** *,** department of mechatronics engineering / al-khwarizmi college of engineering/ university of baghdad/ iraq *** department of faculty engineering/ islamic azad university/ industrial engineering /tehran/ iran **** department of mechanical engineering education/ faculty of engineering/ universitas negeri madan/ indonesia corresponding author: *email: zahraa.nather1994@gmail.com **email: drmahir@kecbu.uobaghdad.edu.iq ***email: azizi@srbiau.ac.ir ****email: sahalaall@unimed.ac.id (received 4 may 2023; accepted 19 october 2023; published 1 march 2024) https://doi.org/10.22153/kej.2024.10.003 abstract the pneumatic circuits have the benefit of having a low energy consumption and not polluting the air. therefore, pneumatic installations are utilized in a variety of technological disciplines. the demands of industrial dynamics call for quick responses and minimal setup periods. pneumatic equipment has to be adaptable and undergo ongoing production cycle changes to meet customer demands for flexibility. quick responses and minimal setup periods. pneumatic equipment must be adaptable and undergo ongoing production cycle changes to meet customer demands for flexibility. this approach is often accomplished by completely rebuilding the system. the control system is part of it. it is easier to adjust to the new job cycle when the control system is included. by using the karnaugh mapping technique, these problems can be solved. the technique enables circuit control with a (plc). this study's goal is to minimize startup times by identifying the collection of ideal logical equations. any pneumatic circuit may be electrically or pneumatically controlled according to the equation. this approach ease creates the process of creating sequence control scheme, whether the scheme uses electro-pneumatic systems or pure pneumatic control. this approach may guarantee both the intended sequential cycle and the least amount of command variables needed to run the control circuit. this research demonstrates how to build a pneumatic control system for the coiling machine's six cylinders using karnaugh maps. the logical equations are generated in a simplified form using the stated principles, and they are easy to use both pneumatically and electro-pneumatically. to implement the technique, pneumatic/electro-pneumatic circuit simulation software is used (automation studio and fluid sim). also, the technique includes ladder diagram language transformation. keywords: industrial automation, karnaugh maps, multiple pneumatic actuators, pneumatic sequential circuits, programmable logic controllers (plcs). 1. introduction compressed air is among the oldest sources of energy. compressed air is now widely distributed and used, and it may be found in all production and service industries. pneumatic refers to the controlled use of this energy source and comes from the greek words meaning blow or breath. drilling, tapping, and other similar operations are excellently suited for mechanization and process automation. hence, the operations replace the human workforce [1]. pneumatic movement of the actuators may be achieved in both translational and rotational directions by alternately adding air to the mailto:zahraa.nather1994@gmail.com mailto:zahraa.nather1994@gmail.com mailto:%20drmahir@kecbu.uobaghdad.edu.iq mailto:azizi@srbiau.ac.ir mailto:sahalaall@unimed.ac.id https://doi.org/10.22153/kej.2024.10.003 alzahraa nather al-khwarizmi engineering journal, vol. 20, no. 1, p.p. 5162 (2024) 52 actuator chambers. directed control valves alternatively direct the compressed air flows to the actuator chambers in order to control this redirection. the execution of movement sequences is the goal of controlling these directional movements. the movement sequences (combinational / sequential cycles) do not present any difference. be combinational or sequential cycles, the control was performed using karnaugh maps (km’s) methodology. in this work, the execution of the control of complicated sequential cycles, was taken into consideration. the execution is based on a set of km derived optimum logic equations that allows for the control of an electrical or pneumatic system. with the help of this technique, pneumatic circuits may be controlled digitally (on/off). by following the rules associated with the methodology, the recommended approach ensures that the needed sequential pneumatic cycle are be performed. in addition, the electrical control in the plc is done. moreover, the direct implementation of instructions obtained through the usage of the karnaugh technique is conducted the control equations become increasingly difficult to derive as the circuit complexity rises. that results from using more cylinders than before (auxiliary memory is frequently needed). additionally, shorter production hours are required by the worldwide market for the industrial sector. it is possible to tackle these problems by applying the karnaugh mapping technique. by identifying the set of reduced equations that enables every pneumatic circuit to be controlled electrically or pneumatically, the goal of this study is to construct multiple-actuator pneumatic circuits and reduce start-up times. the authors in earlier studies [2-4] provided the following objectives: (1) establishing km concepts using a single sequence, (2) using control mathematical equations for pneumatic circuits, (3) adaptation to relay electro-pneumatic control and with plcs. references [2] and [4] explained how km's equations were converted to the ladder schematic (ld) language for use with a siemens s7 200 plc in electro-pneumatic control applications. using artificial intelligence (ai), the control equations were extracted [5]. when there are two alternative control sequences, a way for developing pneumatic control systems was created [6]. the technique for locating the command formulae for the triple sequence for a 4-cylinder, using the karnaugh maps, was described [7]. the author presented three different control sequences for five cylinders using the karnaugh mapping approach in [8]. in this work, the authors develop pneumatic control system in complex cases for 6 cylinders using karnaugh maps. 2. methods and characterizations 2.1 pneumatic system a pneumatic control system is a collection of crucial components for industrial automation systems. pneumatic control system includes many advantages:(1) low cost, (2) easy maintenance, (3) cleanliness, (4) ready availability, (5) inexpensive power supply [9]. by a cylinder and a group of directional control valves, pneumatic control is accomplished. the architecture of any pneumatic actuation system defined by these components is present in practically all pneumatic devices. components may include control, actuation, and position aspects. other components that may be employed in the circuits include logic components (and, or). the goal components is to guarantee that the precise timing of the signals and the compressed air supply to the cylinders is conducted in accordance with the required logic [6] [10]. actuators are traditionally identified by capital letters, while actuator positions at limit switches are identified by lowercase letters. in this case, the cylinder are be represented by (a+) for forward movement and (a-) for a cylinder known as (a) to go rearward. the control cylinder's forward order corresponds to state (a+), while control cylinder’s reverse order corresponds to state (a-). the directional control valve have a similar designation (a) as the control cylinder. 2.2 karnaugh maps method a karnaugh map (km) is a graphical method that minimizes boolean expressions without the use of equation manipulation or boolean algebra theories. a truth table can also be translated into the appropriate logic circuit using km. that enables finding to quickly and methodically the smallest expression of the represented logic function [11]. in a broader sense, this approach addresses issues with industrial control. this technique can be used to create on/off control systems with either compressed air or electricity as the command source. km is widely used due to its simplicity. however, the k-map becomes challenging when the number of variables reaches 5, and 6, and nearly impossible when dealing with more than 6 [12]. alzahraa nather al-khwarizmi engineering journal, vol. 20, no. 1, p.p. 5162 (2024) 53 km is a table of cells. the table has 2n cells (where n is the number of variables). the six-variable km consist of 64 cells, this means the sixth variable has 4 kms of 16 cells each. variable b on the left chooses two of the four km in a row. for the top two kms, the (b0), and for the bottom two kms, the (b1), figure (1). these kms are topped by variable a, which chooses two kms column-wise. the (a0) and (a1) for the left and right kms, respectively. fig. 1. karnaugh maps for six variables (without memory). the basic steps of the karnaugh mapping for constructing electrical and pneumatic control circuits. figure 2 displays the block diagram of the working process. fig. 2. block diagram of working procedure. alzahraa nather al-khwarizmi engineering journal, vol. 20, no. 1, p.p. 5162 (2024) 54 2.3 case study: coiling machine using karnaugh maps this case study involves a six-cylinder configuration figure 3. the coiling machine plays an important role in various productions, this system is used in baghdad/al-rasheed/al-rowad cables company (privet company) first, the cable is pushed to the rotating area under cylinder b directly by the piston of the double-acting cylinder a. next, the cylinder b piston rod is extracted to press the end of the cable to fix it, cylinder a returns, and the motor starts rotating to wind the cable in the form of a pulley. after winding is completed and when the required size is reached, the cylinder c advances to cut the cable and then returns. the conveyor is then moved to the right by extracting the piston rod from cylinder d. after that, cylinder e is extracted to tying the cable roll using plastic tape. cylinder g moves to push the pulley from the conveyor to the box and return to its previous position and cylinder d is then retracted. this completes one working cycle. the cylinders must move in the order shown below for the process just described to be executed automatically: a+\ b+\a-\c+\c-\b-\ d+\e+\ e-\g+\g-\d fig. 3. coiling machine. the representation of the movements of a sequence can be done using the displacement diagram. programming is made simpler and errorfree by the displacement diagrams. in this case, to make the movements more understandable, they are shown in a displacement diagram. the movement chart is displayed in figure 4. description of the system components as shown in the following: a0, a1: limit switch sensors for cylinder a b0, b1: limit switch sensors for cylinder b c0, c1: limit switch sensors for cylinder c d0, d1: limit switch sensors for cylinder d g0, g1: limit switch sensors for cylinder g e0, e1: limit switch sensors for cylinder e alzahraa nather al-khwarizmi engineering journal, vol. 20, no. 1, p.p. 5162 (2024) 55 fig. 4. displacement diagram2.3.1 constructing the karnaugh maps. a karnaugh map for 6 variables (6 cylinders) 26= 64 cells are constructing using four 4-variable maps (16 cells each), figure 5. since more than cylinder advance and back through the sequence, it requires the use of two memories (x) and (y). fig. 5. karnaugh maps for coiling machine with two memories (x and y). alzahraa nather al-khwarizmi engineering journal, vol. 20, no. 1, p.p. 5162 (2024) 56 2.3.2 filling the karnaugh map the sequence's first movement starts at the upper-left area of the map and only occupies one cell in the map. every time there is a movement (a+, a-, b+, b-, etc.), the map must be stretched to twice as many columns. happens in an area that is already occupied. it is assumed that each valve is in its initial positions at the start of the sequence. a 5/2-way valve controls each cylinder. the feedback impulses come from sensors that are close by. all position sequence valve combinations are copied into the km map step by step. as demonstrated by table 1. table 1, relationship between variables and orders 3. result and discussion this section presents the results of the karnaugh map and implementing control. these controls were implemented using a plc electropneumatic implementation, pure pneumatic control, and electrical contacts. that is to convert the equations generated from the kms into control signals. simpler logic equations were extracted by following the suggested rules, and it was based on the previous movement and its location in relation to memory. all active components must thus be present in the equation of motion associated with the a1 order. the active factors in this situation are �̅� (previous movement) and pressing start causes solenoid a+ to extend cylinder a. the final set of equations are shown for all the cylinders using the same approach. 𝐴1 = 𝑠𝑡𝑎𝑟𝑡 �̅� … (1) 𝐴0 = 𝑏1�̅� �̅� … (2) 𝐵1 = 𝑎1�̅� �̅� … (3) 𝐵0 = 𝑐0𝑥 �̅� … (4) 𝐶1 = 𝑎0 𝑏1�̅� �̅� … (5) 𝐶0 = 𝑥 �̅� … (6) 𝐷1 = 𝑏0𝑥 �̅� … (7) 𝐷0 = 𝑔0 �̅�𝑦 … (8) 𝐸1 = 𝑑1𝑥 �̅� … (9) 𝐸0 = �̅� �̅� … (10) 𝐺1 = 𝑒0 𝑑1�̅� �̅� … (11) 𝐺0 = �̅�𝑦 … (12) 𝑋1 = 𝑐1 … (13) 𝑋0 = 𝑒1 … (14) 𝑌1 = 𝑔1 … (15) 𝑌0 = 𝑑0 … (16) 3.1 implementing control from karnaugh maps 3.1.1 pneumatic control and electro pneumatic control electro-pneumatic and pneumatic circuits are handled using a software called fluid sim. schematics for electrical systems can be used in actual systems once they are verified in simulations. the pneumatic and electro-pneumatic circuit is built in accordance with the reduced logic equations, figures 6 and 7. however, the memory is operated by pneumatic valve 5/2. the memory maintains a signal matching the sequence. two memories, x and y, are used in this simulation. the design of pure pneumatic circuit for the coiling machine includes pneumatic parts are: (1) six double acting cylinders cylinder a, b, c, d, g and e, (2)5/2-way directional valve solenoid operated for each cylinder to control the piston movement, (3) exhaust to eliminate the pressure, (4)limit switch sensors two for each cylinder to sense the retracting and extending positions of the cylinders, (5)compressor to compress the air to the desired working pressure. the pneumatic circuit is shown in figure 6. end-of-stroke sensors (initial position) valve control 𝑎0𝑏0𝑐0𝑑0𝑔0𝑒0 a+ 𝑎1𝑏0𝑐0𝑑0𝑔0𝑒0 b+ 𝑎1𝑏1𝑐0𝑑0𝑔0𝑒0 a 𝑎0𝑏1𝑐0𝑑0𝑔0𝑒0 c+ 𝑎0𝑏1𝑐1𝑑0𝑔0𝑒0 c 𝑎0𝑏1𝑐0𝑑0𝑔0𝑒0 b 𝑎0𝑏0𝑐0𝑑0𝑔0𝑒0 d+ 𝑎0𝑏0𝑐0𝑑1𝑔0𝑒0 𝑎0𝑏0𝑐0𝑑1𝑔0𝑒1 𝑎0𝑏0𝑐0𝑑1𝑔0𝑒0 e+ e g+ 𝑎0𝑏0𝑐0𝑑1𝑔1𝑒0 𝑎0𝑏0𝑐0𝑑1𝑔0𝑒0 g d alzahraa nather al-khwarizmi engineering journal, vol. 20, no. 1, p.p. 5162 (2024) 57 fig. 6. pneumatic circuit of coiling machine. the electric parts are push button to control the start of the system, normally open contacts, normally close contacts, and coils, figure 7. the optimized equations derived from the kms are defined as an assemblage of input and output signals linked to multiple cylinder movements during different cycles. the logical equations derived from the kms are transposed to a contact diagram to create the complex sequence's electric scheme, which is made of a number of serial, parallel, or memory components. alzahraa nather al-khwarizmi engineering journal, vol. 20, no. 1, p.p. 5162 (2024) 58 fig. 7. electro-pneumatic control. 3.1.2 plc control the km equations may be used to easily build the electrical control of a pneumatic system; thus, the only necessary step is to turn the equations into plc ladder logic. implementing the required memory that results from the replication of the map will be straightforward thanks to the flexibility of plcs and the ladder. with ladder logic, the simulation application automation studio (v7.0) is utilized to construct the program figure (8). fig. 8. ladder implementation. utilizing a 1214c dc/dc/rly cpu and tia portal v17 software, testing for the implementation and validation of the control system is done. in the first stage, tags are added to all digital inputs, outputs, and memory. implemented the plc program as explained in figure 9. then, a ladder schematic (main ob) is constructed to do the project's necessary tasks and experimental work as shown in figure10. alzahraa nather al-khwarizmi engineering journal, vol. 20, no. 1, p.p. 5162 (2024) 59 fig. 9. plc program in ladder language. alzahraa nather al-khwarizmi engineering journal, vol. 20, no. 1, p.p. 5162 (2024) 60 fig. 10. a), b) and c) experimental work. 4. conclusions a technique is presented that allows fast work in production cycles. they were modified for use with industrial electro-pneumatic and pneumatic control (plc basis or relay). this method enables the resolution of an extremely complex control issue. the logic equations are extracted in a more straightforward form and are easy to employ both pneumatically and electro pneumatically by following the suggested rules. the command equations produced by km ensure that the specified sequence will be carried out and that the number of command variables will be kept to a minimum. the equations may also be readily converted to the ladder diagram's language. this study may contribute to expanding the utility of pneumatic control methodologies. that is by expanding their use beyond industrial applications. applications may cover maintenance, process engineering, and education at the educational level of engineering, with a focus on automation of labs for electro-pneumatic sequential control and pneumatic control circuits. references 4 [1] a. dakre, j. g. sayed, e. a. thorat, a. ahamad, and m. a. chaudhary, “implementation of bottle filling and capping using plc with scada,” int. res. j. eng. technol., pp. 551–558, 2015, [online]. available: www.irjet.net. http://www.irjet.net/ alzahraa nather al-khwarizmi engineering journal, vol. 20, no. 1, p.p. 5162 (2024) 61 [2] a. hussainbaig, r. morales-menendez, and f. guedea, “electro pneumatic control versus grafcet. [3] a. a. santos, “teaching control pneumatic and electropneumatic circuits a new method,” no. september, pp. 1–4, 2015. [4] a. a. santos and a. f. da silva, “methodology for manipulation of karnaugh maps designing for pneumatic sequential logic circuits,” int. j. mechatronics autom., vol. 6, no. 1, pp. 46–54, 2017, doi: 10.1504/ijma.2017.093307. [5] a. f. da silva and a. a. santos, “a simulation tool using ai technics and karnaugh maps for learning and control digital pneumatics,” proc. 2019 5th exp. int. conf. exp.at 2019, pp. 434– 438, 2019, doi: 10.1109/expat.2019.8876488. [6] a. a. santos, “karnaugh maps approach to understanding control implementation behind digital pneumatics,” no. december 2019, 2020 [7] b. a. a. santos and a. ferreira, “adaptability of karnaugh maps to implement and solve complex control problems of pneumatic and electro-pneumatic systems,” vol. 21, no. 2, 2021. [8] a. n. fawzi and m. y. salloom, “developing multiple-actuator pneumatic circuits using the karnaugh maps designing plc controlled,” j. eur. des systèmes autom., vol. 56, no. 2, pp. 245–252, 2023, doi: 10.18280/jesa.560209. [9] k. ahn and s. yokota, “intelligent switching control of pneumatic actuator using on/off solenoid valves,” mechatronics, vol. 15, no. 6, pp. 683–702, jul. 2005, doi: 10.1016/j.mechatronics.2005.01.001. [10] b. bajči, j. šulc, v. reljić, d. šešlija, s. dudić, and i. milenković, “remote laboratory for learning basics of pneumatic control,” lect. notes networks syst., vol. 22, no. january, pp. 144–150, 2018, doi: 10.1007/978-3-319-64352-6_14. [11] “raf. j. of comp. & math’s. , vol. 1 4, no.1, 2020,” vol. 1, no. 1, pp. 97–115, 2020. [12] y. s. abdalla, “introducing the yasser-map as an improvement of the karnaugh-map for solving logical problems,” proc. 2015 ieee int. conf. electr. comput. commun. technol. icecct 2015, pp. 4–8, 2015, doi: 10.1109/icecct.2015.7226152 (2024) 51-62، صفحة 1، العدد20المجلد جلة الخوارزمي الهندسيةم الزهراء نذير 62 هوائية متعددة المحركات تكيف خرائط كارنوف لتنفيذ دوائر هوائية متعددة المحركات الزهراء نذير فوزي* ماهر يحيى سلوم** ****ساهاال سياالكان *** أمير عزيزي جامعة بغداد /الخوارزميكلية الهندسة /الميكاترونكس قسم هندسة*،** طهران /ةجامعة ازاد االسالمي /فرع العلوم والبحوث /كلية الهندسة الصناعية/ ةقسم الهندس*** جامعة نيجيري ميدان/ /كلية الهندسة / يةالميكانيك ةتعليم الهندس اندونيسيا **** قسم zahraa.nather1994@gmail.com. :البريد االلكتروني* drmahir@kecbu.uobaghdad.edu.iq:البريد االلكتروني** azizi@srbiau.ac.ir:البريد االلكتروني*** sahalaall@unimed.ac.id :البريد االلكتروني **** الخالصة التخصصات تتمتع الدوائر الهوائية بميزة انخفاض استهالك الطاقة وعدم تلويث الهواء. لذلك يتم استخدام التركيبات الهوائية في مجموعة متنوعة من ت تتطلب متطلبات الديناميكيات الصناعية استجابات سريعة وفترات إعداد دنيا. يجب أن تكون المعدات الهوائية قابلة للتكيف وتخضع لتغييرا .التكنولوجية امل، بما في ذلك نظام الكمستمرة في دورة اإلنتاج من أجل تلبية متطلبات العمالء من حيث المرونة. غالبًا ما يتم تحقيق هذا النهج من خالل إعادة بناء النظام ب ، يمكن حل هذه المشاكل. تتيح هذه التقنية التحكم في الدائرة karnaugh التحكم ، في محاولة للتكيف مع دورة العمل الجديدة. باستخدام تقنية رسم الخرائط الل تحديد مجموعة المعادالت المنطقية المثلى التي الهدف من هذه الدراسة هو تقليل أوقات بدء التشغيل من خ .(plc) باستخدام وحدة تحكم قابلة للبرمجة تخدم أنظمة كهربائية تسمح بالتحكم في كل دائرة تعمل بالهواء المضغوط كهربائيًا أو هوائيًا. سيسهل هذا النهج إنشاء مخطط التحكم في التسلسل، سواء كان يس الً من الدورة التسلسلية المقصودة وأقل قدر من متغيرات األمر الالزمة لتشغيل دائرة تعمل بالهواء المضغوط أو تحكًما هوائيًا خالًصا. يضمن هذا النهج ك .التحكم إلنشاء نظام تحكم هوائي لست أسطوانات في آلة اللف. باستخدام المبادئ المحددة، تم الحصول karnaugh توضح هذه الدراسة كيفية استخدام خرائط وهي سهلة االستخدام بالهواء المضغوط والكهرباء الهوائية. لتنفيذ هذه التقنية، تم استخدام برنامج محاكاة الدوائر على المعادالت المنطقية في شكل مبسط ، .يمكن أيًضا تحويلها إلى لغة مخطط السلم بسهولة fluid sim)و (automation studio الهوائية / الكهربائية الهوائية mailto:fatima.ibrahim1402@kecbu.uobaghdad.edu.iq mailto:**ahmedalmusawi@kecbu.uobaghdad.edu.iq mailto:azizi@srbiau.ac.ir al-khwarizmi engineering journal al-khwarizmi engineering journal, vol.4 , no.1 , pp 27-47 (2008 ) the effects of vortex generator types on heat transfer and flow structure in a rectangular duct flows (received 25 july 2006; accepted 2 january 2008) abstract: in this numerical study a detailed evaluation of the heat transfer characteristics and flow structure in a laminar and turbulent flow through a rectangular channel containing built-in of different type vortex generator has been a accomplished in a range of reynolds number between 500 and 100,000.a modified version of esceat code has been used to solve navier-stokes and energy equations. the purpose of this paper is to present numerical comparisons in terms of temperature, nusselt number and flow patterns on several configurations of longitudinal vortex generator including new five cases. the structures of heat and flow were studied, using iso-contours of velocity components, vortices, temperature and nusselt number. this study shows that the predicted structures of fluid flow, temperature fields and nusselt number variation are strongly affected by the presence of the turbulators. staggered arrangement gains high nusselt number, also the lower and upper arrangements have higher nusselt number than plane duct. high reynolds number (higher air inlet velocity) will enhance the nusselt number. increase in ribs height will enhance the heat transfer as it works as surface area and turbulator at the same time. keywords: cfd turbulators, heat transfer and fluid flow, rectangular duct. introduction: boundary layer control is any mechanism or process through which the boundary layer is caused to behave differently than it normally would, were the flow developing naturally along a smooth straight surface. examples include reduction / delay or enhancement / triggering of transition, separation, skin friction, or pressure drop, heat transfer, lift, and acoustics. a relatively popular device used in flow control schemes is the vortex generator, vg. these are typically small airfoils that extent from the surface into the flow and produce stream wise vorticity within the boundary layer. vortex generator and micro-vgs are passive control devices, which work well under a narrow range of flow conditions as a result of their inability to be actively varied in response to changes in the flow field. the passive vgs have been used with success, however, they cannot be removed from the flow when unneeded which result in significant parasitic drag. others control systems have used vibrating surfaces, such as small flaps or ribbons, to generate a wallnormal component of velocity within the boundary layer [1]. most previous studies were related to a single circular cylinder or rectangular bluff body immersed in free streams, while other studies are pertinent to flow passing through bluff bodies in confined ducts. for confined turbulent flows past bodies, which usually occur in practice, stochastic three-dimensional turbulent fluctuations are superimposed on the periodic vortex-shedding motion in the wake region. the simulation of large coherent structures in the turbulent wake is difficult because of the widespread spectrum of scales. a resolution of these motions in a dr. waheed s. mohammed asst. prof. mech. eng. dep. university of technology baghdad – iraq dr. sabah tarik ahmed asst. prof. mech. eng. dep. university of technology baghdad – iraq laith j.h. asst. lect. mech. eng. dep. university of technology baghdad – iraq waheed s. mohammed al-khwarizmi engineering journal, vol.4 , no. 1 pp 27-47 (2008) 28 direct simulation is not feasible at present. hence, there is still a need for economic calculation methods based on the use of a turbulence model for simulating the influence of the stochastic fluctuations on the periodic vortex-shedding motion [2]. heat transfer enhancement techniques are found in many of today’s processes. devices such as inclined baffles, rib tabulators, jet impingement, etc. are all used in order to augment the thermal transfer of a process. in applications such as air-cooled solar collectors laser curtain seals electronic cooling, gas-liquid heat exchangers, etc., gases are used instead of liquids as the heat transfer medium. gases inherently have lower heat transfer rates than liquids; therefore heat transfer enhancement techniques that maximize heat transfer are of particular interest. some of the most common heat transfer augmentation techniques are (1) periodic placement of ribs on the heat transfer surface to create boundary layer disturbances; (2) impingement techniques, where high-velocity gas jest are directed at the surface in order to cool it ; (3) internal flow swirls or tape twisters used to create high-levels of turbulence , which , in turn , augment heat transfer ; (4) high free – stream turbulence created by high-velocity jets , situated to inject air flow normal to the mainstream cross flow [3 ]. in electronic devices cooling, for example, and along with the progress of the semiconductor technology, the recent trend in developing electronic devices is toward increased miniaturization of components and compact packaging which result in more heat being generated by the electronic devices and the junction temperature of the electronic devices being higher. the failure rate of the electronic device been statistically corrected to be proportional to the exponential of the electronic device junction temperature. thus the thermal problem has become important for the reliability and performance of new electronic devices and how to enhance heat transfer becomes critical. vortices may naturally induce a flow toward the heat transfer surface. this behavior could augment transverse fluid mixing and reduce the thermal boundary layer thickness. thus the local heat transfer could be enhanced in the neighborhood of the vortices [4]. experimental and numerical studies on the fluid flow and heat transfer in channels with wing-type vgs were carried out by several researchers [5-8]. in spite of the different reynolds numbers and wing’s dimensions and arrangements, the researchers results show that the vgs can generate transfer, longitudinal and horseshoe vortices. these vortices have influences on the velocity and temperature fields and strongly disturb the flow structure. these factors are reasons for heat transfer enhancement by vgs. the effect of rib orientation on local heat transfer distributions and pressure drop in a channel with multi-ribbed walls for a range of reynolds number have been investigated by other researchers [9 & 11]. they also studied the effect of ribs configurations and geometries on the flow and temperature fields. taking both thermal and flow aspects into consideration simultaneously, nusselt number and coefficient of pressure drop increase hand in hand with increasing ratio of promoter height to channel spacing. this tendency is consistent with the increased levels of flow disturbance or turbulence mixing, promoted by the protruding ribs and the installed turbulence promoter. in addition, the permeable ribbed geometry provides a higher thermal performance than the solid-type ribbed, and the best thermal performance occurs. the initiation and subsequent development of the vortexshedding phenomenon was investigated by davis &moore [12] .the properties of these vortices were found to be strongly dependent on reynolds number. the numerical solution was for two-dimensional time-dependent flow for reynolds-number from 100-2800.an experimental investigation of a longitudinal vortex embedded in a turbulent boundary layer was made by eibeck & eaton [13] to increase the physical understanding of the heat transfer effect of a longitudinal vortex. they found that longitudinal vortices usually maintain their coherence over a long, stream wise distance, meaning that the heat transfer effects behind an effective vg are likely to be very persistent. from this previous work review, it found that the most researches were experimental and the numerical studies using cfd for threedimensional laminar and turbulent flows for waheed s. mohammed al-khwarizmi engineering journal, vol.4 , no. 1 pp 27-47 (2008) 29 multi-type vgs were few, thus, the main objective of the present study is to investigate the effect of different pattern flows using several obstacles. the ducts configurations and the several types vgs are presented in figure (1) and table (1). governing equations and numerical details the governing three-dimensional elliptic (pdes) are based on the conservation of mass, momentum and thermal energy. the governing equations of turbulent flow field based on time averaged are as follows [14&15]: (i)continuity equation:)1(.......................................0 z w y v x u          (ii) momentum equation: x-momentum equation: )2(............................. x w zx v y x u xz u zy u y x u xx p1 z )uw( y )uv( x )u( effeff effeffeff eff 2                                                                                y-momentum equation: )3(.............................. y w zy v y y u xz v zy v y x v xy p1 z )vw( y )v( x )uv( effeff effeffeff eff 2                                                                                z-momentum equation: )4(................................. z w zz v y z u xz w zy w y x w xz p1 z )w( y )wv( x )wu( effeff effeffeff eff 2                                                                                (iii) energy equation: )5(........... z t zy t y x t xz tw y tv x ut effeff eff                                           where: υeff = υl + υt & γeff = γl + γt and k cp pr; pr ; pr t t t l l l       the standard k- turbulent model: the standard k- model uses the following transport equations for k and  :       )6(......g z k pr v zy k pr v y x k pr v x kw z kv y ku x k t k t k t                                                )7(..................... k cg k c zpr v z ypr v yxpr v x w z v y u x 2 21 t tt                                                  where: )8(......................... y w z u x w z u x v y u z w 2 y v 2 x u 2g 22 2222 t                                                                  wall function employed the implementation of the wall boundary conditions starts with evaluation of dimensionless quantity. in turbulent flow: )9(............... y kcy p5.0 p 25.0     where yp is the distance of near wall node (p) to the solid surface. a near wall flow is assumed to be laminar if 5.11y and turbulent if 5.11y . constant shear stress (τwall) will be assumed through the wall region: p p wall y u   where up is the velocity at the grid node. the wall force is represented in the discredited momentum equations as follows: )10(.......................af cellwalls  waheed s. mohammed al-khwarizmi engineering journal, vol.4 , no. 1 pp 27-47 (2008) 30 the wall force is introduced into the discredited equation as source term , so )11....(5.11yfora y s cell p p       )12(......5.11yfor eyln kc s 2/1 p 4/1 p       where κ = 0.41 and e = 8.4 the source terms for the turbulent flow in the discredited k-equation are represented as: )13.........( v y u s v y ey lnkcs p pw u p 2/1 p 4/3 p                       where v is the wall control volume. the discredited -equation is fixed to the value:   )14(........................... 2/34/3 p p p y kc       in the discredited -equation the near wall node is fixed to the given value in eq.(14) by means of setting the source terms sp and su as follows: )15.(.................... 10 y kc s 10s 30 p 2/3 p 4/3 u 30 p            there are several differencing schemes available for use in deriving the fdes from their pdes, however, power-law scheme is used in this paper. the coefficients in this scheme read: )16.......( f,0) d f 1.01(,0da f,0) d f 1.01(,0da w 5 w e ww e 5 e e ee          which means that; )17....( 10peif0.0a and,10pe0if) d f 1.01(da ,0pe10iff) d f 1.01(da ,10peiffa e 5 e e ee e 5 e e ee ee                nusselt number i) laminar case: the local nusselt number on the duct walls and on the obstacles surfaces is defined by: )18(................ n/n t/)tt( n t nu inwalln         the average nusselt number was calculated by numerical integration over the length of the lines of the surface and then over the length of the channel using trapezoidal method. ii) turbulent case: the local nusselt number: )19(.......... )ttb( w)tt(prhd stnu wall nwallnt       where: 4/1 l t t l j 2 p w jt 2 pw ) pr pr ()1 pr pr (0.9p, ) u p1(pr u/ st       and for more details about (up) and (tb) see waheed [15]. also the average nusselt number was calculated as described in the laminar case. the applied conditions a. initial u = v = 0 , w = win , k = kin= 0.00135 * ( win) 2 , ε = ε in= 0.09 * (kin) 1.5 / (0.03 * hd) , t = tref b. at inlet u = v = 0 , w = win , k = kin , ε = ε in , μ = μref , t = tin c. at walls and vgs surfaces u = v = w = k = ε = 0 , μ = μref , t = twall d. at exit all variables equal to the same variables just before one plane. a finite volume technique with staggered grids combined with the simple algorithm is used to solve navier-stokes and energy equations, patanker [16].the vgs are represented by making the velocities (u, v, and w) are equal to zero at the baffle location grids, and the temperatures are equal to the waheed s. mohammed al-khwarizmi engineering journal, vol.4 , no. 1 pp 27-47 (2008) 31 temperature of the wall that the vgs are placed. for solving the finite difference equations, the calculation domain is divided into a number of control volumes. each control volume is associated with particular dependent variable. in the method to be described, the aim is to calculate the main dependent variables at a number of chosen points called the grid points. the governing differential equations are discredited reduced to algebraic equations by constructing a control volume surrounding each grid point. there are several possible ways in which the control volumes are chosen. the most obvious way of constructing the control volumes in this study is to place their faces midway between neighboring grid points, see the distribution bellow. results and discussion using the previously described numerical method, computations have been carried out for flow and heat transfer. the parameters involved are vg types, reynolds number, duct and vgs configurations and dimensions, will be discussed below, see table. in order to justify the present computations, comparisons have been made with two sets of numerical predictions and experimental data from other sources. figure (2) shows comparison of an experimental data of eibeck et al.[13], for laminar flow in a channel with built-in winglet type vg (case h). the results agree well with the experiment. figure (3) shows another comparison of the computational result of sabah [17], with the present result for laminar flow in a smooth duct (1*1*2) m3. again both calculations display good agreement. on the whole, it appears that the present procedure has demonstrated its ability to successfully simulate the development of the complex turbulent flow and other complicated flows using several vg configurations as shown in figure (1). one of these is case (a), it is presented in figure (4) which shows a 4finned duct, the first pair at bottom wall at ( z = 0.231 m ) and the second pair at top wall at ( z = 0.502 m ). the obtained velocities, vectors, temperatures contours and nusselt number are presented in this figure. figure (4-a to d) are for laminar case where tin=20co and twall=50co and figure (4-e&f) are for turbulent case where tin=10co and twall=40co. figure (4-a) presents the streamwise mean velocity vector fields around the fins at ( x = 0.016 m ). the approaching flow below the vg height is retarded and turned upward near vg’s front edge to flow over the vg. it is interesting to note that there is no corner vortex formed in the front of the vgs. comparison of the span wise-average nusselt number distributions between upper and lower walls of the duct is tackled in figure (4-b). there is a peak on each of the curves of nusselt number in front of vgs. after this peak and after the vortex generators the level of nusselt number along the duct decreases and reaches to an approximately constant level. the local nusselt number for the upper wall is shown in figure (4-c). the peaks are appearing clearly. figure (4-d) represents the temperature contours at cross section ( z = 0.502 m ). it shows how the y z x 0,0,0 z x y n n b b f f e e w w s s waheed s. mohammed al-khwarizmi engineering journal, vol.4 , no. 1 pp 27-47 (2008) 32 fins affected the thermal boundary layer. for turbulent flow, figure (4-e&f) shows the temperature contours at (z-y) plane and average nusselt number for the four walls of the duct respectively. fig. (4-e) shows the temperature variation along the duct at ( x = 0.032 m ). in fig. (4-f) the nusselt number shows larger amplitude of the variation for the upper and lowers finned walls than the right and left walls. airflow in the duct and nu variation on rib surfaces in a vertical ribbed duct (case b) are shown in figure (5). the rib location is at ( x = 0.048 m & z = 0.382 m ) and tin=7 co while the wall or rib surface temperature is twall=27 co. figure (5-a) gave the vectors of flow in three-dimensions at ( z = 0.016, 0.133, 0.273, 0.413, 0.553 m ), it shows the velocity distribution and how the rib affected the flow. while figure (5-b) gave the average nu variation on rib surfaces, it is appearing that the front surface have the larger nu than the rear face. the effects of horizontal fin (case c) on the temperature and nu for laminar flow are shown in fig. (6), the fin at ( z = 0.382 m & y = 0.04 m ) and ( tin=7 co & twall=27 co ). fig. (6-a) shows the temperature contours at ( z = 0.382 m ), it shows how the fin makes an additional heated object to add new thermal boundary layer. the average nu along the faces of the fin can be seen in fig. (6-b) which shows the low nu near the ends of the fin because the effect of the thermal boundary layer. fig. (7) highlighted the effects of case d on the flow, temperature and nu for laminar and turbulent flows, the horizontal rib at ( z = 0.484 m & y = 0.09 m ) and the vertical one at ( z = 1.054 m & x = 0.18 m ) while (tin=16 co & twall=40 co ) for laminar flow and ( tin=10 co & twall=40 co ) for turbulent flow. fig. (7-a) represents the temperature contours for laminar flow at (z = 0.057, 0.256, 0.541, 0.826, 1.111, 1.395, and 1.68 m), it is clear that the ribs make a circular contours of the temperatures. while fig. (7-b) shows the isotherms at (y = 0.09 m), it can be seen that the ribs increase the mixing between the cold flow and the hot surfaces. the variation of nu has been represented in fig. (7-c to e) for laminar case. fig. (7-c) shows the variation of average nu at the horizontal rib surfaces, and fig. (7-d) at the vertical rib surfaces, it show that large nu occurs in the middle of the ribs. fig. (7-e) highlighted the local nu at the left surface of the vertical rib. the turbulent flow are tackled in fig. (7-f&g), where fig. (7-f) shows the velocity (u-v) vectors at the end of the duct, the vortices are very clear in this figure, while fig. (7-g) shows the velocity (w/win) vectors at (x-z) plane (y = 0.09 m), it is appear how the ribs change the velocity distribution in the end of the duct. fig. (8) presents case e for laminar flow, where fig. (8-a) gave the (u/win -component) velocity at ( z = 0.382 m) and shows the symmetric contours. fig. (8-b) gave the (v/win component) velocity at the same position and shows the symmetric values of the velocity at the beginning of the duct. for oblique vg (case f), fig. (9) depicts temperatures, velocities, and nusselt numbers for laminar and turbulent flows. the vortex structure is weakened or even broken after its retardation by the divider wall. as a result, nu decreases as described in fig. (9-a&b) for laminar flow where ( tin=20 co & twall=50 co ) and fig. (9-b) for bottom wall. for turbulent flow pattern, fig. (9-c) depicts the (vcomponent) velocity contours along the duct at ( z = 0.027, 0.095, 0.204, 0.339, 0.475, 0.611, and 0.746 m ). the velocity contours (w/win) at station (z = 0.393 m) are depicted in fig. (9-d). there are strong interactions between the longitudinal vortices and the boundary layer on the walls of the duct, especially the lower wall. these interactions affect the structure of the velocity or the thermal boundary layer by thinning it in the downwash region on the lower wall while the opposite trend occurs on the upper wall, see (v-component) velocity contours (fig. (9-c)) and cross flow velocity contours (fig. (9-d)) and temperature contours along the duct (fig. (9-e)) at ( x = 0.16 m ) where ( tin=10 co & twall=40 co ). the average nu variations along the duct for the four walls are tackled in fig. (9-f) for turbulent flow. the highest nu compared with the laminar case (fig. (9-a)) is due to the effects of the additional variables of shear stress and high velocities. the effect of broken rib (case g) on velocities, nusselt, stanton numbers are presented in fig. (10). the first rib is placed at (z = 0.312 m) and the other at (z = 0.583 m). for laminar flows where ( tin=20 co & waheed s. mohammed al-khwarizmi engineering journal, vol.4 , no. 1 pp 27-47 (2008) 33 twall=50 co ), fig. (10-a) shows that when the vgs are exposed to the main flow, due to pressure difference between two sides of vg, flow separation occurs and longitudinal vortices are generated. fig. (10-b) represents local nu for left wall, it shows how the nu increases because of the increase of heat transfer area and temperature difference and the influence of the vortices. fig. (10-c) shows span wise local nu, nu(z), in the stream wise direction. the nu(z) fluctuates in the regions where the vgs exist. on the other hand, the variation of nu(z) are approximately similar in the upstream of vgs. and for turbulent flows where ( tin=10 co & twall=40 co ), fig. (10-d) represents velocity (w) vectors in (x-z) plane, it can be seen that the presence of ribs causes the flow to bend and impinge significantly on the right and left walls and on the upstream surface of ribs. the average nu described in fig. (10-e), it shows a small increase in the nu in the beginning of the duct and an increase of nn(z) in vgs region. the local stanton number presented in fig. (10-f), it is appear that the stanton number increases in front of the ribs and then decreases behind the ribs and then increases again and decreases downstream. figure (11) describes the simulation of laminar and turbulent flow for delta winglet and winglet pair (case h & case i). fig. (11-a) describes the local nu for case h for laminar flow where ( tin=16 co & twall=40 co ), it shows that the winglet divide the duct into two similar parts and then increase nu very little. for turbulent flow where ( tin=10 co &twall=40 co), fig. (11-b) describes the secondary velocity vectors (u-v components) for case i. as the vortex developed, the secondary velocities decreased and the core radius increased. case j is presented in figure (12), the laminar flow are tackled in fig. (12-a to d) where (tin=7 co & twall=27 co ), while the turbulent flow are tackled in fig. (12-e to g) where ( tin=10 co & twall=40 co). a small recirculation zone is found behind the lower heated obstacles as shown in fig. (12-a). weak clockwise vortices are formed within the grooves, which is similar to the cavity flow. these recirculation zones and vortices are impediments to the heat transfer from the heated obstacles. the temperature contours are shown in fig. (12-b) at (z = 0.142 m), which described the isotherms distribution across the duct as a hot rib and walls and cold core. fig. (12-c) shows the isotherms at ( z = 0.144 m ), it is clear that the upper rib increases the mixing layer and then enhances heat transfer. the variations of average nu along the ribs face are indicated in fig. (12-d), which indicates that the values of nu distribution surrounding the back face of the upper rib are higher than for other ribs. this indicates that a smaller recirculating vortex exists behind the upper rib compared to subsequent ribs. fig. (12-e) indicates the stereamwise mean velocity (w) contours; it shows the small vortices that formatted behind the solid bottom ribs. fig. (12-f) illustrates the average nu for the four-sided duct. the results show that the average nu on the ribbed sidewall has large fluctuations decreases slowly with distance, due to flow separation from ribs and decreases after flow reattaching on the surface and then increase again before flow hits next rib. the local stanton numbers for the bottom wall are illustrated in fig. (12-g). several features are immediately appearing. the first vortex causes a peak augmentation of the local st, and then the local heat transfer coefficient. the span wise variations in the st can be directly related to the mean velocity field. the minimum in the st curve is associated with the up wash region, where warm, low-momentum fluid from the near-wall zone is swept up ward to thicken the boundary layer. finally, fig. (13) shows the effect of case k on velocity, temperature, nu and st numbers for laminar flow (fig. (13-a to d)) and for turbulent flow (fig. (13-e to g)) where ( tin=10 co & twall=40 co ). fig. (13-a) indicates the temperature contours at ( z = 0.531 m ), the influence of the vortex pair is very clear. and the average nu has been presented in fig. (13b) for the four-sided wall. it is clear that the roughened walls have a large value than the smooth walls. it can bee seen from this figure that the average nu for right and left walls starts out high and then gradually tapers off. this is to be expected as the thermal boundary layer develops within the duct. and for top finned wall, it can be seen that the fins result in higher average nu, it is also observed that the addition of the fins produces an oscillating shape in the curve of the nu along the duct. waheed s. mohammed al-khwarizmi engineering journal, vol.4 , no. 1 pp 27-47 (2008) 34 also for bottom-baffled wall, a higher nu is achieved. here, the baffle increases the local airflow velocity at the heated surface by reducing the cross-sectional area of the duct. the local nu for top wall with 4-fins and for bottom wall with wing-type vg are presented in fig. (13-c & d) respectively. high nu can be attributed to the fact that the turbulators are causing flow separation and reattachment, as well as interrupting the boundary layer, causing high turbulence local to the heated surface. the periodicity in fig. (13-b & c) can be attributed to the periodic placement of the fins and the fact that the flow separation is occurring before and after the fins. these points of separation result in local “hotspots”, which translate into a reduction in the nusselt numbers. fig. (13-e) at ( z = 1.68 m ) shows that for delta wing in a duct flow the divergence of the vortex axes prevails but the cross-section becomes strongly elliptic. the symmetry planes set limits to the possible divergence of the vortices, and the walls set limits to their vertical movement. fig. (13-f) illustrate the st for bottom wall with wing-type vg, it shows large fluctuations decreases with distance. fig. (13-g) shows the average nu for the four walls, the upper and lower roughened walls have a larger value than the right and left smooth walls. conclusions the following are been concluding from the present work: 1. longitudinal vortices of moderate size and strength have been found to cause a significant perturbation in the heat transfer behavior of an otherwise threedimensional boundary layer. local st increases and decreases, resulting in a net increase in the span wise-averaged heat transfer coefficient or nu. 2. the use of a turbulence promoter can effectively improve the heat transfer characteristics and avoid the occurrence of hotspots in the high-temperature regime. in addition, it enhances not only the heat transfer performance of its downstream ribs, but also that of its upstream ribs. 3. when the side-wall confinement is appropriately utilized, most of the up wash sides of the longitudinal vortex pairs induced by the vgs arranged in a proper pitch can be truncated resulting in a large area of the vortex-generator mounted wall exposed to the downwash sides of the longitudinal vortex pairs and, in turn, high heat transfer augmentation. 4. the vgs are punched out of the fin and they generate swirling motion in the flows in the duct formed by the fin and thereby increase the heat transfer. 5. with the exception of the configurations, the addition of ribs always improved the average nu number. 6. combining ribs with baffles yielded an increase in average nu. therefore, a situation where rate of heat transfer is critical to the performance of a device combining ribs with baffle is a viable solution. waheed s. mohammed al-khwarizmi engineering journal, vol.4 , no. 1 pp 27-47 (2008) 35 fig. (1) types of vortex generators used (the figures not to scale): a) fins, b) vertical rib ,c) horizontal fin, and d) horizontal & vertical rib,e) vertical fins, and f) oblique rib ,g) staggered ribs, h) delta-winglet. y x z a b l h b b c d f h α e h g l waheed s. mohammed al-khwarizmi engineering journal, vol.4 , no. 1 pp 27-47 (2008) 36 fig. (1) continue: i) pair of winglets, j) multi-ribs, and k) wing & fins. table (1) duct and vgs configuration. case vg type configurations grid size re duct vg b (m) h (m) l (m) b (mm) h (mm) l (mm) β (o) α (o) laminar turbulent a staggered fins 0.32 0.16 0.8 48 24 --90 90 21*21*31 1,500 100,000 b vertical rib 0.16 0.08 0.6 32 80 16 90 90 11*19*40 750 7,500 c horizontal fin 0.16 0.08 0.6 160 5 --90 90 20*19*40 2,119 21,191 d horizontal and vertical ribs 0.4 0.2 1.68 horizontal 21*21*31 500 5,000 400 20 57 90 90 vertical 40 200 57 90 90 e staggered 2-fins 0.16 0.08 0.6 32 80 --90 90 11*19*40 750 7,502 f oblique rib 0.32 0.16 0.8 320 20 54 90 55.4 9*18*31 1,500 12,800 g broken ribs 0.32 0.16 0.8 50 16 27 90 90 21*21*31 2,000 10,000 h delta winglet 0.12 0.055 0.7 10 15 46 90 12 25*12*70 1,700 12,571 i 2-delta winglet 0.12 0.055 0.7 10 15 46 90 12 25*12*70 1,700 17,000 -12 j 5continuous horizontal ribs 0.16 0.08 0.6 4-at bottom wall 90 90 11*19*50 750 14,222 160 13 12 last one 160 4 12 k delta wing with horizontal 4-fins 0.4 0.2 1.68 delta wing 26*15*60 1,000 5,000 144 157 316 26 90 4-fins 400 14 --90 90 w k β ji waheed s. mohammed al-khwarizmi engineering journal, vol.4 , no. 1 pp 27-47 (2008) 37 ( a ) ( b ) fig. (2) secondary flow velocity vectors at z = 0.6 m (a) present result (b) data of [13]. 0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 z 0.00 0.20 0.40 0.60 0.80 1.00 y ( a ) ( b ) fig. (3) variation of (w/win) at mid plane and re=100: (a) present result (b) result of [17]. 5 0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.6 0.65 z ( m ) x y z 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 z ( m ) 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 nu duct walls bottom wall top wall ( a ) ( b ) 0 0.04 0.08 0.12 0.16 0.2 0.24 0.28 0.32 x ( m ) 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 y ( m ) ( c ) ( d ) fig.(4) variation of flow field and isothermal contour and nu for finned duct. re=1,500: (a) velocity vectors, (b) average nu, (c) local nu at upper wall, (d) temperature contours. waheed s. mohammed al-khwarizmi engineering journal, vol.4 , no. 1 pp 27-47 (2008) 38 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 z ( m ) 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 y ( m ) 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 z ( m ) 0 25 50 75 100 125 150 175 200 225 250 275 300 325 350 375 nu loc duct walls bottom wall top wall right wall left wall ( e ) ( f ) fig.(4) continue , re=100,000: (e) isothermal contours, and (f) average nu. 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.6 z ( m )0 0.03 0.06 0.09 0.12 0.15x ( m ) 0 0.025 0.05 0.075 y ( m ) x y z 0.0 1.0 2.0 3.0 4.0 nu 0.00 0.02 0.04 0.06 0.08 h ( m ) rib surfaces front surface rear surface ( a ) ( b ) fig. (5) velocity vectors and nu for vertical ribbed duct. re=750: (a) velocity vectors in five selected planes, and (b) average nu on rib’s two surfaces. 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 x ( m ) 0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 y ( m ) 0 1 2 3 4 5nu 0.00 0.04 0.08 0.12 0.16 b ( m ) fin faces rear face front face bottom face top face ( a ) ( b ) fig. (6) temperature contours and nu for case c. re=2,119: (a) temperature distributions, and (b) average nu. waheed s. mohammed al-khwarizmi engineering journal, vol.4 , no. 1 pp 27-47 (2008) 39 0 0.05 0.1 0.15 0.2 y ( m ) 0 0.1 0.2 0.3 0.4 x ( m ) 0 0.2 0.4 0.6 0 .8 1 1.2 1.4 1.6 z ( m ) 1 5 14 14 12 13 10 11 13 9 9 14 12 13 10109 9 13 13 14 10 9 14 911 14 1 3 15 11 1213 1210 9 15 6 1314 5 15 14 1 3 5 15 10 9 8 12 11 8 7 9 8 1 4 8 107 1 3 11 7 15 1 5 10 12 12 13 12 13 4 12 15 14 7 15 4 15 10 10 13 11 11 14 3 7 14 9 10 15 12 8 3 10 814 7 3 12 9 8 9 15 9 15 6 5 4 7 8 1112 15 7 8 6 14 7 15 10156 11 8 11 15 12 23 14 12 614 7 10 5 1 5 124 11 1 1 10 6 7911 56 7 11 713 7 13 1113 2 15 7 11 1 1 13 x y z 1 16 2 17.7143 3 19.4286 4 21.1429 5 22.8571 6 24.5714 7 26.2857 8 28 9 29.7143 10 31.4286 11 33.1429 12 34.8571 13 36.5714 14 38.2857 15 40 0 0.24 0.48 0.72 0.96 1.2 1.44 1.68 z ( m ) 0 0.1 0.2 0.3 0.4 x ( m ) ( a ) ( b ) 0.00 1.00 2.00 3.00 4.00 nu 0.00 0.10 0.20 0.30 0.40 b ( m ) rib faces rear face front face bottom face top face 0.00 0.50 1.00 1.50 2.00 2.50 nu 0.00 0.04 0.08 0.12 0.16 0.20 h ( m ) rib surfaces rear surface front surface right surface left surface 1.08 1.1 1.12 z ( m ) 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 h ( m ) ( c ) ( d ) ( e ) 0 0.05 0.1 0.15 0.2 y ( m ) 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 x ( m ) 0.02 00.10.2 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 z ( m) 0 0.1 0.2 0.3 0.4 x ( m ) y x z 1 ( f ) ( g ) fig. (7) temperature contours, nu, and velocity vectors for case d. re=500: (a) temperature distributions, (b) temperatures at (x-z) plane, (c) average nu for horizontal rib, (d) average nu for vertical rib, (e) local nu for vertical rib, re=5,000: (f) velocity vectors in (x-y) plane, (g) velocity vectors in (x-z) plane. 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 x ( m ) 0 0.02 0.04 0.06 0.08 y ( m ) ( a ) ( b ) fig. (8) velocities distributions for case e. re=750: (a) u/win , (b) v/win . waheed s. mohammed al-khwarizmi engineering journal, vol.4 , no. 1 pp 27-47 (2008) 40 0.00 0.20 0.40 0.60 0.80 z ( m ) 0.40 0.80 1.20 1.60 2.00 nu duct walls bottom wall top wall right wall left wall ( a ) ( b ) 0 0 .1 0 .2 0 .3 0 .4 0 .5 0 .6 0.7 0 .8 z ( m ) 0 0 .1 0 .2 0 .3x ( m ) 0 0 .05 0 .1 0 .15 y ( m ) 43 43 40 4337 43 37 34 40 40 3 1 43 43 3 4 3 1 37 3140 31 43 22 31 34 40 71 7 43 37 43 252525 37 43 34343743 43 43 40 4 0 4 3 43 40 4343 43 4 3 43 46 46 43 46 4 6 y x z 4 9 0 .0 4 23 8 78 4 6 0 .0 1 77 6 34 4 3 -0 .0 1 09 6 5 4 0 -0 .0 4 37 9 76 3 7 -0 .0 6 84 2 2 3 4 -0 .1 0 53 5 9 3 1 -0 .1 2 99 8 3 2 8 -0 .1 6 69 2 2 5 -0 .1 9 15 4 4 2 2 -0 .2 2 43 7 6 1 9 -0 .2 5 31 0 5 1 6 -0 .2 7 77 2 9 1 3 -0 .3 1 46 6 6 1 0 -0 .3 3 92 9 7 -0 .3 7 62 2 7 4 -0 .4 0 08 5 1 1 -0 .4 3 77 8 8 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 z ( m ) 0 0.05 0.1 0.15 y ( m ) ( c ) ( d ) 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 z ( m ) 0 0.05 0.1 0.15 y ( m ) 0.00 0.20 0.40 0.60 0.80 z ( m ) 0.00 10.00 20.00 30.00 40.00 50.00 nu duct walls bottom wall top wall right wall left wall ( e ) ( f ) fig. (9) nu variations, velocity vectors and temperature contours, for case f. re=1,500: (a) average nu, (b) local nu at bottom wall, re=12,800: (c) v contours, (d) w/win distribution, (e) isotherms, (f) average nu for turbulent case. waheed s. mohammed al-khwarizmi engineering journal, vol.4 , no. 1 pp 27-47 (2008) 41 0.1 0.2 0.3 0.4 0.5 0.6 0.7 z ( m ) 0.1 0.2 0.3 y ( m ) ( a ) ( b ) 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 z ( m ) 0.00 0.50 1.00 1.50 2.00 2.50 nu duct walls bottom wall top wall right wall left wall 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 z ( m ) 0 0.1 0.2 0.3 x ( m ) y x z 0.1 ( c ) ( d ) 0.00 0.20 0.40 0.60 0.80 z ( m ) 10.00 20.00 30.00 40.00 50.00 60.00 nu duct walls bottom wall top wall right wall left wall ( e ) ( f ) fig. (10) nu variations and velocity vectors for case g. for laminar flow re=2,000: (a) velocity vectors, (b) local nu, (c) average nu, and for turbulent flow re=10,000: (d) velocity vectors, (e) local nu, (f) local stanton number. waheed s. mohammed al-khwarizmi engineering journal, vol.4 , no. 1 pp 27-47 (2008) 42 0.006 0.056 0.106 0.156 0.206 0.256 0.306 0.356 0.406 0.456 0.506 0.556 0.606 0.656 z ( m ) 0.005 0.025 0.045 0.065 0.085 0.105 x ( m ) 0 0.01 0.02 0.03 0.04 0.05 y ( m ) 0 0.02 0.04 0.06 0.08 0.1 0.12 x ( m ) ( a ) ( b ) fig. (11) nu variations and velocity vectors for cases h & i. re=1,700: (a) local nu, re=17,000: (b) velocity vectors. 0 0.02 0.04 0.06 0.08 y ( m ) 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.6 z(m) x y z1 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 x ( m ) 0 0.02 0.04 0.06 0.08 y ( m ) 27 ( a ) ( b ) 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.6 z ( m ) 0 0.02 0.04 0.06 0.08 y ( m ) 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 x ( m ) 0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 y ( m ) ribs back faces upper rib fourth rib third rib second rib first rib ( c ) ( d ) fig. (12) velocity distributions, temperature contours, nu, and st numbers for case j. for laminar flow re=750: (a) velocity vectors, (b) temperature contours, (c) isotherms, (d) average nu. waheed s. mohammed al-khwarizmi engineering journal, vol.4 , no. 1 pp 27-47 (2008) 43 0 0.02 0.04 0.06 0.08 y ( m ) 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.6 z(m) 11 9 6 11 5 9 11 6 9 6 111010 8 11 4 11 5 6 13 11 12 7 13 14 89 3 14 5 68 14131011 55 9 7 5 8 4 11 1 5 2 5 47 3 58 414 41312 11 1 0 1 1 12 6139 14 6 1113 68 9 10 8 11556 1113 1 -0.224 2 -0.139 3 -0.053 4 0.033 5 0.118 6 0.204 7 0.289 8 0.375 9 0.461 10 0.546 11 0.632 12 0.717 13 0.803 14 0.889 15 0.974 0.10 0.30 0.500.00 0.20 0.40 0.60 z ( m ) 20 60 100 140 0 40 80 120 160 nu duct walls bottom wall top wall right wall left wall ( e ) ( f ) ( g ) fig. (12) continue, for turbulent flow re=14,222: (e) velocity (w) vectors, (f) average nu, (g) local st. 0.00 0.21 0.42 0.63 0.84 1.05 1.26 1.47 1.68 z 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 nu duct walls top smooth bottom smooth top ribbed bottom baffled 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 x ( m ) 0 0.04 0.08 0.12 0.16 y ( m ) ( a ) ( b ) fig. (13) velocity vectors, temperature contours, nu, and st numbers for case k. for laminar flow re=1,000: (a) temperature contours, (b) average nu. waheed s. mohammed al-khwarizmi engineering journal, vol.4 , no. 1 pp 27-47 (2008) 44 0.015 0.165 0.315 0.465 0.615 0.765 0.915 1.065 1.215 1.365 1.515 z ( m ) 0.016 0.106 0.196 0.286 0.376 x ( m ) 0.015 0.155 0.295 0.435 0.575 0.715 0.855 0.995 1.135 1.275 1.415 1.555 z ( m ) 0.016 0.106 0.196 0.286 0.376 x ( m ) ( c ) ( d ) 0 0.05 0.1 0.15 0.2 y ( m ) 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 x ( m ) 0.1 ( e ) ( f ) 0.00 0.21 0.42 0.63 0.84 1.05 1.26 1.47 1.68 z ( m ) 0 5 10 15 20 25 30 35 40 45 nu duct and vg walls bottom with wing walls top with ribs walls bottom smooth walls top smooth walls ( g ) fig. (13) continue, (c) local nu for top wall with ribs, (d) local nu for bottom wall with wing, for turbulent flow re=5,000: (e) velocity vectors, (f) local st for bottom wall with vg, (g) average nu with vg. waheed s. mohammed al-khwarizmi engineering journal, vol.4 , no. 1 pp 27-47 (2008) 45 nomenclature greek symbol coefficients in general finite-domain equationae , aw inclination angle in (x-z) plane αwall area of the control volume acell angle of attack in (y-z) planeβwidth of the vg (wing span)b diffusion coefficient гwidth of the ductb rate of dissipation of kε coefficient in turbulence models, =1.43, 1.92, 0.09 respectively c1ε,c2ε,cμ von karman’s constantκspecific heatcp dynamic viscosityμdiffusion terms de , dw kinematics viscosity υlogarithmic wall constant e fluid densityρconvection coefficients fe , fw prandtl numberσwall force fs wall shear stressτwallgeneration rate of turbulence energyg subscriptvg heighth effective value effduct heighth control volume faces e , w hydraulic diameterhd condition at inletinturbulent kinetic energyk refer to turbulence model equation k , εthermal conductivity of the fluid k laminar flow condition lvg length or thickness or chord l normal distance from a wall nduct length l duct dimensions = b , h , ln nusselt number nu central node and its neighbors ( east and west ) p , e , wpressure p turbulent flow conditiontfinite-domain cell peclet numberpe condition at wallwallprandtl numberpr superscript stanton number st dimensionless value+reynolds number re abbreviationtemperature t elliptic equation solver for convection and heat transfer esceatbulk temperature tb two-equations turbulence model k-εfield reference temperature tref simi-implicit method for pressure linked equation simplemean velocity componentsu,v,w vortex generator vgcoordinate directions x,y,z waheed s. mohammed al-khwarizmi engineering journal, vol.4 , no. 1 pp 27-47 (2008) 46 references 1jeffrey alan taylor, “ development of an ‘ active wing’ for the validation 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transfer enhancement by vortex generator ”, september 2001, ph.d. thesis, dept. of mechanical engineering, university of technology. waheed s. mohammed al-khwarizmi engineering journal, vol.4 , no. 1 pp 27-47 (2008) 47 ! !ƒ! !! ! !œ!! ! œ! ! !œ!! !!! œƒ! ! !œ!¾!! ! !!! œ! š!œ!¾œ!!!œ!! !! !! !œ! !!œ!! œ!!! ! !! œ! !œ!! œ! ƒ!!!!!! !! !!!!!!!! š! !! !œ! !!ƒš!!! ! !!ÿ! !!! !! œ!! ! !!!! ! !!! !!! !!! ! !š! !! !! !!!!!ÿ! !š!!!! !!!!!!!! šœ!ž ! œ! !! œ!!!! ! !!ÿ! !!! !! œ!! ! !!!!! !!! !!! !!! ! !š! !! !! !!!!!ÿ! !š!!!! !!!!! ƒ!š!! ž!! !! ƒ!!! ! !!ÿ! !!! !! œ!! ! !!!! ! !!! !!! !!! ! !š! !! !! !!!!!ÿ! !š!!!! !! ! ! ! ! !œ!!! ! !!¿! ! !! !!! ! ! ! !! !! !!!! !!!! !!! š!!!! ! !! !!! !!! š!!!¿! ! ! !!! !! ! !!!¿!!!!!!! œ!! ! !! !! ! !!!!! !! ! !!!!! ! !! !!!!!!! !! ž !! !! ! !! ! š!!! !!!! ! !ƒ! ! !!¿!!!! !! !! ! !! !!! !!! !!!! !!! ! !! !! !! !! !!!!!! !!500!!! !!100,000!!!!! ! ! ! !!! ! !!!!!! !! !!!!!! !! ! !!! !!! !! !(esceat)! !! !!!! ! !!!!ÿ! !¿! !!! !!!! !!! ! ! ! !!!!! !! !!! ! ! ! ! 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( ..... .......... y k c y p 5 . 0 p 25 . 0 m × × r × = m + 5 . 11 £ + y 5 . 11 > + y p p wall y u × = m t ) 10 ( ... .......... .......... a f cell wall s × t = ) 11 ....( 5 . 11 y for a y s cell p p £ × m = + ( ) ) 12 ( ...... 5 . 11 y for ey ln k c s 2 / 1 p 4 / 1 p > k × × × r = + + m ) 13 .........( v y u s v y ey ln k c s p p w u p 2 / 1 p 4 / 3 p ï ï þ ï ï ý ü d × × t = d × ÷ ÷ ø ö ç ç è æ k × × × r = + m ( ) ) 14 ( ....... .......... .......... 2 / 3 4 / 3 p p p y k c × × = k e m ) 15 .( .......... .......... 10 y k c s 10 s 30 p 2 / 3 p 4 / 3 u 30 p ï þ ï ý ü ´ × k × = = m ) 16 .......( f , 0 ) d f 1 . 0 1 ( , 0 d a f , 0 ) d f 1 . 0 1 ( , 0 d a w 5 w e w w e 5 e e e e ï ï þ ï ï ý ü > + < + > < = > < + > < = ) 17 ....( 10 pe if 0 . 0 a and , 10 pe 0 if ) d f 1 . 0 1 ( d a , 0 pe 10 if f ) d f 1 . 0 1 ( d a , 10 pe if f a e 5 e e e e e 5 e e e e e e ï ï ï ï þ ï ï ï ï ý ü > = £ £ = < £ = < = ) 18 ( ...... .......... n / n t / ) t t ( n t nu in wall n d = ¶ ¶ = + + ) 19 ( .......... ) t tb ( w ) t t ( pr hd st nu wall n wall n t × r × × m × × = 4 / 1 l t t l j 2 p w j t 2 p w ) pr pr ( ) 1 pr pr ( 0 . 9 p , ) u p 1 ( pr u / st × × = × r t + × × r t = ε ε ε ε ε 0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 z 0 . 0 0 0 . 2 0 0 . 4 0 0 . 6 0 0 . 8 0 1 . 0 0 y 0 . 1 0 . 1 5 0 . 2 0 . 2 5 0 . 3 0 . 3 5 0 . 4 0 . 4 5 0 . 5 0 . 5 5 0 . 6 0 . 6 5 0 . 7 0 . 7 5 z ( m ) x y z 0 . 0 0 . 1 0 . 2 0 . 3 0 . 4 0 . 5 0 . 6 0 . 7 0 . 8 z ( m ) 0 . 0 0 . 2 0 . 4 0 . 6 0 . 8 1 . 0 1 . 2 1 . 4 1 . 6 1 . 8 2 . 0 2 . 2 n u d u c t w a l l s b o t t o m w a l l t o p w a l l 0 0.04 0.08 0.12 0.16 0.2 0.24 0.28 0.32 x ( m ) 0 0 . 0 2 0 . 0 4 0 . 0 6 0 . 0 8 0 . 1 0 . 1 2 0 . 1 4 0 . 1 6 y ( m ) 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 z ( m ) 0 0 . 0 2 0 . 0 4 0 . 0 6 0 . 0 8 0 . 1 0 . 1 2 0 . 1 4 0 . 1 6 y ( m ) 0 . 0 0 . 1 0 . 2 0 . 3 0 . 4 0 . 5 0 . 6 0 . 7 0 . 8 z ( m ) 0 2 5 5 0 7 5 1 0 0 1 2 5 1 5 0 1 7 5 2 0 0 2 2 5 2 5 0 2 7 5 3 0 0 3 2 5 3 5 0 3 7 5 n u l o c d u c t w a l l s b o t t o m w a l l t o p w a l l r i g h t w a l l l e f t w a l l 0 0 . 0 5 0 . 1 0 . 1 5 0 . 2 0 . 2 5 0 . 3 0 . 3 5 0 . 4 0 . 4 5 0 . 5 0 . 5 5 0 . 6 z ( m ) 0 0 . 0 3 0 . 0 6 0 . 0 9 0 . 1 2 0 . 1 5 x ( m ) 0 0 . 0 2 5 0 . 0 5 0 . 0 7 5 y ( m ) x y z 0 . 0 1 . 0 2 . 0 3 . 0 4 . 0 n u 0 . 0 0 0 . 0 2 0 . 0 4 0 . 0 6 0 . 0 8 h ( m ) r i b s u r f a c e s f r o n t s u r f a c e r e a r s u r f a c e 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 x ( m ) 0 0 . 0 1 0 . 0 2 0 . 0 3 0 . 0 4 0 . 0 5 0 . 0 6 0 . 0 7 0 . 0 8 y ( m ) 0 1 2 3 4 5 n u 0 . 0 0 0 . 0 4 0 . 0 8 0 . 1 2 0 . 1 6 b ( m ) f i n f a c e s r e a r f a c e f r o n t f a c e b o t t o m f a c e t o p f a c e 0 0 . 0 5 0 . 1 0 . 1 5 0 . 2 y ( m ) 0 0 . 1 0 . 2 0 . 3 0 . 4 x ( m ) 0 0 . 2 0 . 4 0 . 6 0 . 8 1 1 . 2 1 . 4 1 . 6 z ( m ) 1 5 1 4 1 4 1 2 1 3 1 0 1 1 1 3 9 9 1 4 1 2 1 3 1 0 1 0 9 9 1 3 1 3 1 4 1 0 9 1 4 9 1 1 1 4 1 3 1 5 1 1 1 2 1 3 1 2 1 0 9 1 5 6 1 3 1 4 5 1 5 1 4 1 3 5 1 5 1 0 9 8 1 2 1 1 8 7 9 8 1 4 8 1 0 7 1 3 1 1 7 1 5 1 5 1 0 1 2 1 2 1 3 1 2 1 3 4 1 2 1 5 1 4 7 1 5 4 1 5 1 0 1 0 1 3 1 1 1 1 1 4 3 7 1 4 9 1 0 1 5 1 2 8 3 1 0 8 1 4 7 3 1 2 9 8 9 1 5 9 1 5 6 5 4 7 8 1 1 1 2 1 5 7 8 6 1 4 7 1 5 1 0 1 5 6 1 1 8 1 1 1 5 1 2 2 3 1 4 1 2 6 1 4 7 1 0 5 1 5 1 2 4 1 1 1 1 1 0 6 7 9 1 1 5 6 7 1 1 7 1 3 7 1 3 1 1 1 3 2 1 5 7 1 1 1 1 1 3 x y z 1 1 6 2 1 7 . 7 1 4 3 3 1 9 . 4 2 8 6 4 2 1 . 1 4 2 9 5 2 2 . 8 5 7 1 6 2 4 . 5 7 1 4 7 2 6 . 2 8 5 7 8 2 8 9 2 9 . 7 1 4 3 1 0 3 1 . 4 2 8 6 1 1 3 3 . 1 4 2 9 1 2 3 4 . 8 5 7 1 1 3 3 6 . 5 7 1 4 1 4 3 8 . 2 8 5 7 1 5 4 0 0 0.24 0.48 0.72 0.96 1.2 1.44 1.68 z ( m ) 0 0 . 1 0 . 2 0 . 3 0 . 4 x ( m ) 0 . 0 0 1 . 0 0 2 . 0 0 3 . 0 0 4 . 0 0 n u 0 . 0 0 0 . 1 0 0 . 2 0 0 . 3 0 0 . 4 0 b ( m ) r i b f a c e s r e a r f a c e f r o n t f a c e b o t t o m f a c e t o p f a c e 0 . 0 0 0 . 5 0 1 . 0 0 1 . 5 0 2 . 0 0 2 . 5 0 n u 0 . 0 0 0 . 0 4 0 . 0 8 0 . 1 2 0 . 1 6 0 . 2 0 h ( m ) r i b s u r f a c e s r e a r s u r f a c e f r o n t s u r f a c e r i g h t s u r f a c e l e f t s u r f a c e 1.08 1.1 1.12 z ( m ) 0 . 0 2 0 . 0 4 0 . 0 6 0 . 0 8 0 . 1 0 . 1 2 0 . 1 4 0 . 1 6 0 . 1 8 h ( m ) 0 0 . 0 5 0 . 1 0 . 1 5 0 . 2 y ( m ) 0 0 . 0 5 0 . 1 0 . 1 5 0 . 2 0 . 2 5 0 . 3 0 . 3 5 0 . 4 x ( m ) 0 . 0 2 0 0 . 1 0 . 2 0 0 . 2 0 . 4 0 . 6 0 . 8 1 1 . 2 1 . 4 1 . 6 z ( m ) 0 0 . 1 0 . 2 0 . 3 0 . 4 x ( m ) y x z 1 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 x ( m ) 0 0 . 0 2 0 . 0 4 0 . 0 6 0 . 0 8 y ( m ) 0 . 0 0 0 . 2 0 0 . 4 0 0 . 6 0 0 . 8 0 z ( m ) 0 . 4 0 0 . 8 0 1 . 2 0 1 . 6 0 2 . 0 0 n u d u c t w a l l s b o t t o m w a l l t o p w a l l r i g h t w a l l l e f t w a l l 0 0 . 1 0 . 2 0 . 3 0 . 4 0 . 5 0 . 6 0 . 7 0 . 8 z ( m ) 0 0 . 1 0 . 2 0 . 3 x ( m ) 0 0 . 0 5 0 . 1 0 . 1 5 y ( m ) 4 3 4 3 4 0 4 3 3 7 4 3 3 7 3 4 4 0 4 0 3 1 4 3 4 3 3 4 3 1 3 7 3 1 4 0 3 1 4 3 2 2 3 1 3 4 4 0 7 1 7 4 3 3 7 4 3 2 5 2 5 2 5 3 7 4 3 3 4 3 4 3 7 4 3 4 3 4 3 4 0 4 0 4 3 4 3 4 0 4 3 4 3 4 3 4 3 4 3 4 6 4 6 4 3 4 6 4 6 y x z 4 9 0 . 0 4 2 3 8 7 8 4 6 0 . 0 1 7 7 6 3 4 4 3 0 . 0 1 0 9 6 5 4 0 0 . 0 4 3 7 9 7 6 3 7 0 . 0 6 8 4 2 2 3 4 0 . 1 0 5 3 5 9 3 1 0 . 1 2 9 9 8 3 2 8 0 . 1 6 6 9 2 2 5 0 . 1 9 1 5 4 4 2 2 0 . 2 2 4 3 7 6 1 9 0 . 2 5 3 1 0 5 1 6 0 . 2 7 7 7 2 9 1 3 0 . 3 1 4 6 6 6 1 0 0 . 3 3 9 2 9 7 0 . 3 7 6 2 2 7 4 0 . 4 0 0 8 5 1 1 0 . 4 3 7 7 8 8 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 z ( m ) 0 0 . 0 5 0 . 1 0 . 1 5 y ( m ) 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 z ( m ) 0 0 . 0 5 0 . 1 0 . 1 5 y ( m ) 0 . 0 0 0 . 2 0 0 . 4 0 0 . 6 0 0 . 8 0 z ( m ) 0 . 0 0 1 0 . 0 0 2 0 . 0 0 3 0 . 0 0 4 0 . 0 0 5 0 . 0 0 n u d u c t w a l l s b o t t o m w a l l t o p w a l l r i g h t w a l l l e f t w a l l 0 0 . 0 5 0 . 1 0 . 1 5 y ( m ) 0 0 . 1 0 . 2 0 . 3 x ( m ) x y z 0 . 0 2 5 0.1 0.2 0.3 0.4 0.5 0.6 0.7 z ( m ) 0 . 1 0 . 2 0 . 3 y ( m ) 0 . 0 0 . 1 0 . 2 0 . 3 0 . 4 0 . 5 0 . 6 0 . 7 0 . 8 z ( m ) 0 . 0 0 0 . 5 0 1 . 0 0 1 . 5 0 2 . 0 0 2 . 5 0 n u d u c t w a l l s b o t t o m w a l l t o p w a l l r i g h t w a l l l e f t w a l l 0 0 . 1 0 . 2 0 . 3 0 . 4 0 . 5 0 . 6 0 . 7 0 . 8 z ( m ) 0 0 . 1 0 . 2 0 . 3 x ( m ) y x z 0 . 1 0 . 0 0 0 . 2 0 0 . 4 0 0 . 6 0 0 . 8 0 z ( m ) 1 0 . 0 0 2 0 . 0 0 3 0 . 0 0 4 0 . 0 0 5 0 . 0 0 6 0 . 0 0 n u d u c t w a l l s b o t t o m w a l l t o p w a l l r i g h t w a l l l e f t w a l l 0.006 0.056 0.106 0.156 0.206 0.256 0.306 0.356 0.406 0.456 0.506 0.556 0.606 0.656 z ( m ) 0 . 0 0 5 0 . 0 2 5 0 . 0 4 5 0 . 0 6 5 0 . 0 8 5 0 . 1 0 5 x ( m ) 0 0 . 0 1 0 . 0 2 0 . 0 3 0 . 0 4 0 . 0 5 y ( m ) 0 0 . 0 2 0 . 0 4 0 . 0 6 0 . 0 8 0 . 1 0 . 1 2 x ( m ) 0 0 . 0 2 0 . 0 4 0 . 0 6 0 . 0 8 y ( m ) 0 0 . 0 5 0 . 1 0 . 1 5 0 . 2 0 . 2 5 0 . 3 0 . 3 5 0 . 4 0 . 4 5 0 . 5 0 . 5 5 0 . 6 z ( m ) x y z 1 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 x ( m ) 0 0 . 0 2 0 . 0 4 0 . 0 6 0 . 0 8 y ( m ) 27 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.6 z ( m ) 0 0 . 0 2 0 . 0 4 0 . 0 6 0 . 0 8 y ( m ) 0 . 5 1 . 0 1 . 5 2 . 0 2 . 5 3 . 0 3 . 5 4 . 0 x ( m ) 0 . 0 0 0 . 0 2 0 . 0 4 0 . 0 6 0 . 0 8 0 . 1 0 0 . 1 2 0 . 1 4 0 . 1 6 y ( m ) r i b s b a c k f a c e s u p p e r r i b f o u r t h r i b t h i r d r i b s e c o n d r i b f i r s t r i b 0 0 . 0 2 0 . 0 4 0 . 0 6 0 . 0 8 y ( m ) 0 0 . 0 5 0 . 1 0 . 1 5 0 . 2 0 . 2 5 0 . 3 0 . 3 5 0 . 4 0 . 4 5 0 . 5 0 . 5 5 0 . 6 z ( m ) 1 1 9 6 1 1 5 9 1 1 6 9 6 1 1 1 0 1 0 8 1 1 4 1 1 5 6 1 3 1 1 1 2 7 1 3 1 4 8 9 3 1 4 5 6 8 1 4 1 3 1 0 1 1 5 5 9 7 5 8 4 1 1 1 5 2 5 4 7 3 5 8 4 1 4 4 1 3 1 2 1 1 1 0 1 1 1 2 6 1 3 9 1 4 6 1 1 1 3 6 8 9 1 0 8 1 1 5 5 6 1 1 1 3 1 0 . 2 2 4 2 0 . 1 3 9 3 0 . 0 5 3 4 0 . 0 3 3 5 0 . 1 1 8 6 0 . 2 0 4 7 0 . 2 8 9 8 0 . 3 7 5 9 0 . 4 6 1 1 0 0 . 5 4 6 1 1 0 . 6 3 2 1 2 0 . 7 1 7 1 3 0 . 8 0 3 1 4 0 . 8 8 9 1 5 0 . 9 7 4 0 . 1 0 0 . 3 0 0 . 5 0 0 . 0 0 0 . 2 0 0 . 4 0 0 . 6 0 z ( m ) 2 0 6 0 1 0 0 1 4 0 0 4 0 8 0 1 2 0 1 6 0 n u d u c t w a l l s b o t t o m w a l l t o p w a l l r i g h t w a l l l e f t w a l l 0 . 0 0 0 . 2 1 0 . 4 2 0 . 6 3 0 . 8 4 1 . 0 5 1 . 2 6 1 . 4 7 1 . 6 8 z 0 . 2 0 0 . 4 0 0 . 6 0 0 . 8 0 1 . 0 0 1 . 2 0 1 . 4 0 1 . 6 0 1 . 8 0 2 . 0 0 n u d u c t w a l l s t o p s m o o t h b o t t o m s m o o t h t o p r i b b e d b o t t o m b a f f l e d 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 x ( m ) 0 0 . 0 4 0 . 0 8 0 . 1 2 0 . 1 6 y ( m ) 0.015 0.165 0.315 0.465 0.615 0.765 0.915 1.065 1.215 1.365 1.515 z ( m ) 0 . 0 1 6 0 . 1 0 6 0 . 1 9 6 0 . 2 8 6 0 . 3 7 6 x ( m ) 0.015 0.155 0.295 0.435 0.575 0.715 0.855 0.995 1.135 1.275 1.415 1.555 z ( m ) 0 . 0 1 6 0 . 1 0 6 0 . 1 9 6 0 . 2 8 6 0 . 3 7 6 x ( m ) 0 0 . 0 5 0 . 1 0 . 1 5 0 . 2 y ( m ) 0 0 . 0 5 0 . 1 0 . 1 5 0 . 2 0 . 2 5 0 . 3 0 . 3 5 0 . 4 x ( m ) 0 . 1 0 . 0 0 0 . 2 1 0 . 4 2 0 . 6 3 0 . 8 4 1 . 0 5 1 . 2 6 1 . 4 7 1 . 6 8 z ( m ) 0 5 1 0 1 5 2 0 2 5 3 0 3 5 4 0 4 5 n u d u c t a n d v g w a l l s b o t t o m w i t h w i n g w a l l s t o p w i t h r i b s w a l l s b o t t o m s m o o t h w a l l s t o p s m o o t h w a l l s cooling of electronic equipment has been studied in great detail in recent years waheed s. mohammed al-khwarizmi engineering journal, vol.4 , no. 1 pp 27-47 (2008) al-khwarizmi engineering journal al-khwarizmi engineering journal, vol.4 , no.1 , pp 27-47 (2008 ) the effects of vortex generator types on heat transfer and flow structure in a rectangular duct flows dr. waheed s. mohammed asst. prof. mech. eng. dep. university of technology baghdad – iraq dr. sabah tarik ahmed asst. prof. mech. eng. dep. university of technology baghdad – iraq laith j.h. asst. lect. mech. eng. dep. university of technology baghdad – iraq (received 25 july 2006; accepted 2 january 2008) abstract: in this numerical study a detailed evaluation of the heat transfer characteristics and flow structure in a laminar and turbulent flow through a rectangular channel containing built-in of different type vortex generator has been a accomplished in a range of reynolds number between 500 and 100,000.a modified version of esceat code has been used to solve navier-stokes and energy equations. the purpose of this paper is to present numerical comparisons in terms of temperature, nusselt number and flow patterns on several configurations of longitudinal vortex generator including new five cases. the structures of heat and flow were studied, using iso-contours of velocity components, vortices, temperature and nusselt number. this study shows that the predicted structures of fluid flow, temperature fields and nusselt number variation are strongly affected by the presence of the turbulators. staggered arrangement gains high nusselt number, also the lower and upper arrangements have higher nusselt number than plane duct. high reynolds number (higher air inlet velocity) will enhance the nusselt number. increase in ribs height will enhance the heat transfer as it works as surface area and turbulator at the same time. keywords: cfd turbulators, heat transfer and fluid flow, rectangular duct. introduction: boundary layer control is any mechanism or process through which the boundary layer is caused to behave differently than it normally would, were the flow developing naturally along a smooth straight surface. examples include reduction / delay or enhancement / triggering of transition, separation, skin friction, or pressure drop, heat transfer, lift, and acoustics. a relatively popular device used in flow control schemes is the vortex generator, vg. these are typically small airfoils that extent from the surface into the flow and produce stream wise vorticity within the boundary layer. vortex generator and micro-vgs are passive control devices, which work well under a narrow range of flow conditions as a result of their inability to be actively varied in response to changes in the flow field. the passive vgs have been used with success, however, they cannot be removed from the flow when unneeded which result in significant parasitic drag. others control systems have used vibrating surfaces, such as small flaps or ribbons, to generate a wall-normal component of velocity within the boundary layer [1]. most previous studies were related to a single circular cylinder or rectangular bluff body immersed in free streams, while other studies are pertinent to flow passing through bluff bodies in confined ducts. for confined turbulent flows past bodies, which usually occur in practice, stochastic three-dimensional turbulent fluctuations are superimposed on the periodic vortex-shedding motion in the wake region. the simulation of large coherent structures in the turbulent wake is difficult because of the widespread spectrum of scales. a resolution of these motions in a direct simulation is not feasible at present. hence, there is still a need for economic calculation methods based on the use of a turbulence model for simulating the influence of the stochastic fluctuations on the periodic vortex-shedding motion [2]. heat transfer enhancement techniques are found in many of today’s processes. devices such as inclined baffles, rib tabulators, jet impingement, etc. are all used in order to augment the thermal transfer of a process. in applications such as air-cooled solar collectors laser curtain seals electronic cooling, gas-liquid heat exchangers, etc., gases are used instead of liquids as the heat transfer medium. gases inherently have lower heat transfer rates than liquids; therefore heat transfer enhancement techniques that maximize heat transfer are of particular interest. some of the most common heat transfer augmentation techniques are (1) periodic placement of ribs on the heat transfer surface to create boundary layer disturbances; (2) impingement techniques, where high-velocity gas jest are directed at the surface in order to cool it ; (3) internal flow swirls or tape twisters used to create high-levels of turbulence , which , in turn , augment heat transfer ; (4) high free –stream turbulence created by high-velocity jets , situated to inject air flow normal to the mainstream cross flow [3 ]. in electronic devices cooling, for example, and along with the progress of the semiconductor technology, the recent trend in developing electronic devices is toward increased miniaturization of components and compact packaging which result in more heat being generated by the electronic devices and the junction temperature of the electronic devices being higher. the failure rate of the electronic device been statistically corrected to be proportional to the exponential of the electronic device junction temperature. thus the thermal problem has become important for the reliability and performance of new electronic devices and how to enhance heat transfer becomes critical. vortices may naturally induce a flow toward the heat transfer surface. this behavior could augment transverse fluid mixing and reduce the thermal boundary layer thickness. thus the local heat transfer could be enhanced in the neighborhood of the vortices [4]. experimental and numerical studies on the fluid flow and heat transfer in channels with wing-type vgs were carried out by several researchers [5-8]. in spite of the different reynolds numbers and wing’s dimensions and arrangements, the researchers results show that the vgs can generate transfer, longitudinal and horseshoe vortices. these vortices have influences on the velocity and temperature fields and strongly disturb the flow structure. these factors are reasons for heat transfer enhancement by vgs. the effect of rib orientation on local heat transfer distributions and pressure drop in a channel with multi-ribbed walls for a range of reynolds number have been investigated by other researchers [9 & 11]. they also studied the effect of ribs configurations and geometries on the flow and temperature fields. taking both thermal and flow aspects into consideration simultaneously, nusselt number and coefficient of pressure drop increase hand in hand with increasing ratio of promoter height to channel spacing. this tendency is consistent with the increased levels of flow disturbance or turbulence mixing, promoted by the protruding ribs and the installed turbulence promoter. in addition, the permeable ribbed geometry provides a higher thermal performance than the solid-type ribbed, and the best thermal performance occurs. the initiation and subsequent development of the vortexshedding phenomenon was investigated by davis &moore [12] .the properties of these vortices were found to be strongly dependent on reynolds number. the numerical solution was for two-dimensional time-dependent flow for reynolds-number from 100-2800.an experimental investigation of a longitudinal vortex embedded in a turbulent boundary layer was made by eibeck & eaton [13] to increase the physical understanding of the heat transfer effect of a longitudinal vortex. they found that longitudinal vortices usually maintain their coherence over a long, stream wise distance, meaning that the heat transfer effects behind an effective vg are likely to be very persistent. from this previous work review, it found that the most researches were experimental and the numerical studies using cfd for three-dimensional laminar and turbulent flows for multi-type vgs were few, thus, the main objective of the present study is to investigate the effect of different pattern flows using several obstacles. the ducts configurations and the several types vgs are presented in figure (1) and table (1). governing equations and numerical details the governing three-dimensional elliptic (pdes) are based on the conservation of mass, momentum and thermal energy. the governing equations of turbulent flow field based on time averaged are as follows [14&15]: (i)continuity equation:(ii) momentum equation: x-momentum equation: y-momentum equation: z-momentum equation: (iii) energy equation: where: υeff = υl + υt & γeff = γl + γt and the standard k-( turbulent model: the standard k-( model uses the following transport equations for k and ( : where: wall function employed the implementation of the wall boundary conditions starts with evaluation of dimensionless quantity. in turbulent flow: where yp is the distance of near wall node (p) to the solid surface. a near wall flow is assumed to be laminar if and turbulent if . constant shear stress (τwall) will be assumed through the wall region: where up is the velocity at the grid node. the wall force is represented in the discredited momentum equations as follows: the wall force is introduced into the discredited equation as source term , so where κ = 0.41 and e = 8.4 the source terms for the turbulent flow in the discredited k-equation are represented as: where (v is the wall control volume. the discredited (-equation is fixed to the value: in the discredited (-equation the near wall node is fixed to the given value in eq.(14) by means of setting the source terms sp and su as follows: there are several differencing schemes available for use in deriving the fdes from their pdes, however, power-law scheme is used in this paper. the coefficients in this scheme read: which means that; nusselt number i) laminar case: the local nusselt number on the duct walls and on the obstacles surfaces is defined by: the average nusselt number was calculated by numerical integration over the length of the lines of the surface and then over the length of the channel using trapezoidal method. ii) turbulent case: the local nusselt number: where: and for more details about (up) and (tb) see waheed [15]. also the average nusselt number was calculated as described in the laminar case. the applied conditions a. initial u = v = 0 , w = win , k = kin= 0.00135 * ( win)2 , = in= 0.09 * (kin)1.5 / (0.03 * hd) , t = tref b. at inlet u = v = 0 , w = win , k = kin , = in , μ = μref , t = tin c. at walls and vgs surfaces u = v = w = k = = 0 , μ = μref , t = twall d. at exit all variables equal to the same variables just before one plane. a finite volume technique with staggered grids combined with the simple algorithm is used to solve navier-stokes and energy equations, patanker [16].the vgs are represented by making the velocities (u, v, and w) are equal to zero at the baffle location grids, and the temperatures are equal to the temperature of the wall that the vgs are placed. for solving the finite difference equations, the calculation domain is divided into a number of control volumes. each control volume is associated with particular dependent variable. in the method to be described, the aim is to calculate the main dependent variables at a number of chosen points called the grid points. the governing differential equations are discredited reduced to algebraic equations by constructing a control volume surrounding each grid point. there are several possible ways in which the control volumes are chosen. the most obvious way of constructing the control volumes in this study is to place their faces midway between neighboring grid points, see the distribution bellow. results and discussion using the previously described numerical method, computations have been carried out for flow and heat transfer. the parameters involved are vg types, reynolds number, duct and vgs configurations and dimensions, will be discussed below, see table. in order to justify the present computations, comparisons have been made with two sets of numerical predictions and experimental data from other sources. figure (2) shows comparison of an experimental data of eibeck et al.[13], for laminar flow in a channel with built-in winglet type vg (case h). the results agree well with the experiment. figure (3) shows another comparison of the computational result of sabah [17], with the present result for laminar flow in a smooth duct (1*1*2) m3. again both calculations display good agreement. on the whole, it appears that the present procedure has demonstrated its ability to successfully simulate the development of the complex turbulent flow and other complicated flows using several vg configurations as shown in figure (1). one of these is case (a), it is presented in figure (4) which shows a 4-finned duct, the first pair at bottom wall at ( z = 0.231 m ) and the second pair at top wall at ( z = 0.502 m ). the obtained velocities, vectors, temperatures contours and nusselt number are presented in this figure. figure (4-a to d) are for laminar case where tin=20co and twall=50co and figure (4-e&f) are for turbulent case where tin=10co and twall=40co. figure (4-a) presents the streamwise mean velocity vector fields around the fins at ( x = 0.016 m ). the approaching flow below the vg height is retarded and turned upward near vg’s front edge to flow over the vg. it is interesting to note that there is no corner vortex formed in the front of the vgs. comparison of the span wise-average nusselt number distributions between upper and lower walls of the duct is tackled in figure (4-b). there is a peak on each of the curves of nusselt number in front of vgs. after this peak and after the vortex generators the level of nusselt number along the duct decreases and reaches to an approximately constant level. the local nusselt number for the upper wall is shown in figure (4-c). the peaks are appearing clearly. figure (4-d) represents the temperature contours at cross section ( z = 0.502 m ). it shows how the fins affected the thermal boundary layer. for turbulent flow, figure (4-e&f) shows the temperature contours at (z-y) plane and average nusselt number for the four walls of the duct respectively. fig. (4-e) shows the temperature variation along the duct at ( x = 0.032 m ). in fig. (4-f) the nusselt number shows larger amplitude of the variation for the upper and lowers finned walls than the right and left walls. airflow in the duct and nu variation on rib surfaces in a vertical ribbed duct (case b) are shown in figure (5). the rib location is at ( x = 0.048 m & z = 0.382 m ) and tin=7 co while the wall or rib surface temperature is twall=27 co. figure (5-a) gave the vectors of flow in three-dimensions at ( z = 0.016, 0.133, 0.273, 0.413, 0.553 m ), it shows the velocity distribution and how the rib affected the flow. while figure (5-b) gave the average nu variation on rib surfaces, it is appearing that the front surface have the larger nu than the rear face. the effects of horizontal fin (case c) on the temperature and nu for laminar flow are shown in fig. (6), the fin at ( z = 0.382 m & y = 0.04 m ) and ( tin=7 co & twall=27 co ). fig. (6-a) shows the temperature contours at ( z = 0.382 m ), it shows how the fin makes an additional heated object to add new thermal boundary layer. the average nu along the faces of the fin can be seen in fig. (6-b) which shows the low nu near the ends of the fin because the effect of the thermal boundary layer. fig. (7) highlighted the effects of case d on the flow, temperature and nu for laminar and turbulent flows, the horizontal rib at ( z = 0.484 m & y = 0.09 m ) and the vertical one at ( z = 1.054 m & x = 0.18 m ) while (tin=16 co & twall=40 co ) for laminar flow and ( tin=10 co & twall=40 co ) for turbulent flow. fig. (7-a) represents the temperature contours for laminar flow at (z = 0.057, 0.256, 0.541, 0.826, 1.111, 1.395, and 1.68 m), it is clear that the ribs make a circular contours of the temperatures. while fig. (7-b) shows the isotherms at (y = 0.09 m), it can be seen that the ribs increase the mixing between the cold flow and the hot surfaces. the variation of nu has been represented in fig. (7-c to e) for laminar case. fig. (7-c) shows the variation of average nu at the horizontal rib surfaces, and fig. (7-d) at the vertical rib surfaces, it show that large nu occurs in the middle of the ribs. fig. (7-e) highlighted the local nu at the left surface of the vertical rib. the turbulent flow are tackled in fig. (7-f&g), where fig. (7-f) shows the velocity (u-v) vectors at the end of the duct, the vortices are very clear in this figure, while fig. (7-g) shows the velocity (w/win) vectors at (x-z) plane (y = 0.09 m), it is appear how the ribs change the velocity distribution in the end of the duct. fig. (8) presents case e for laminar flow, where fig. (8-a) gave the (u/win -component) velocity at ( z = 0.382 m) and shows the symmetric contours. fig. (8-b) gave the (v/win -component) velocity at the same position and shows the symmetric values of the velocity at the beginning of the duct. for oblique vg (case f), fig. (9) depicts temperatures, velocities, and nusselt numbers for laminar and turbulent flows. the vortex structure is weakened or even broken after its retardation by the divider wall. as a result, nu decreases as described in fig. (9-a&b) for laminar flow where ( tin=20 co & twall=50 co ) and fig. (9-b) for bottom wall. for turbulent flow pattern, fig. (9-c) depicts the (v-component) velocity contours along the duct at ( z = 0.027, 0.095, 0.204, 0.339, 0.475, 0.611, and 0.746 m ). the velocity contours (w/win) at station (z = 0.393 m) are depicted in fig. (9-d). there are strong interactions between the longitudinal vortices and the boundary layer on the walls of the duct, especially the lower wall. these interactions affect the structure of the velocity or the thermal boundary layer by thinning it in the downwash region on the lower wall while the opposite trend occurs on the upper wall, see (v-component) velocity contours (fig. (9-c)) and cross flow velocity contours (fig. (9-d)) and temperature contours along the duct (fig. (9-e)) at ( x = 0.16 m ) where ( tin=10 co & twall=40 co ). the average nu variations along the duct for the four walls are tackled in fig. (9-f) for turbulent flow. the highest nu compared with the laminar case (fig. (9-a)) is due to the effects of the additional variables of shear stress and high velocities. the effect of broken rib (case g) on velocities, nusselt, stanton numbers are presented in fig. (10). the first rib is placed at (z = 0.312 m) and the other at (z = 0.583 m). for laminar flows where ( tin=20 co & twall=50 co ), fig. (10-a) shows that when the vgs are exposed to the main flow, due to pressure difference between two sides of vg, flow separation occurs and longitudinal vortices are generated. fig. (10-b) represents local nu for left wall, it shows how the nu increases because of the increase of heat transfer area and temperature difference and the influence of the vortices. fig. (10-c) shows span wise local nu, nu(z), in the stream wise direction. the nu(z) fluctuates in the regions where the vgs exist. on the other hand, the variation of nu(z) are approximately similar in the upstream of vgs. and for turbulent flows where ( tin=10 co & twall=40 co ), fig. (10-d) represents velocity (w) vectors in (x-z) plane, it can be seen that the presence of ribs causes the flow to bend and impinge significantly on the right and left walls and on the upstream surface of ribs. the average nu described in fig. (10-e), it shows a small increase in the nu in the beginning of the duct and an increase of nn(z) in vgs region. the local stanton number presented in fig. (10-f), it is appear that the stanton number increases in front of the ribs and then decreases behind the ribs and then increases again and decreases downstream. figure (11) describes the simulation of laminar and turbulent flow for delta winglet and winglet pair (case h & case i). fig. (11-a) describes the local nu for case h for laminar flow where ( tin=16 co & twall=40 co ), it shows that the winglet divide the duct into two similar parts and then increase nu very little. for turbulent flow where ( tin=10 co &twall=40 co), fig. (11-b) describes the secondary velocity vectors (u-v components) for case i. as the vortex developed, the secondary velocities decreased and the core radius increased. case j is presented in figure (12), the laminar flow are tackled in fig. (12-a to d) where (tin=7 co & twall=27 co ), while the turbulent flow are tackled in fig. (12-e to g) where ( tin=10 co & twall=40 co). a small recirculation zone is found behind the lower heated obstacles as shown in fig. (12-a). weak clockwise vortices are formed within the grooves, which is similar to the cavity flow. these recirculation zones and vortices are impediments to the heat transfer from the heated obstacles. the temperature contours are shown in fig. (12-b) at (z = 0.142 m), which described the isotherms distribution across the duct as a hot rib and walls and cold core. fig. (12-c) shows the isotherms at ( z = 0.144 m ), it is clear that the upper rib increases the mixing layer and then enhances heat transfer. the variations of average nu along the ribs face are indicated in fig. (12-d), which indicates that the values of nu distribution surrounding the back face of the upper rib are higher than for other ribs. this indicates that a smaller recirculating vortex exists behind the upper rib compared to subsequent ribs. fig. (12-e) indicates the stereamwise mean velocity (w) contours; it shows the small vortices that formatted behind the solid bottom ribs. fig. (12-f) illustrates the average nu for the four-sided duct. the results show that the average nu on the ribbed sidewall has large fluctuations decreases slowly with distance, due to flow separation from ribs and decreases after flow reattaching on the surface and then increase again before flow hits next rib. the local stanton numbers for the bottom wall are illustrated in fig. (12-g). several features are immediately appearing. the first vortex causes a peak augmentation of the local st, and then the local heat transfer coefficient. the span wise variations in the st can be directly related to the mean velocity field. the minimum in the st curve is associated with the up wash region, where warm, low-momentum fluid from the near-wall zone is swept up ward to thicken the boundary layer. finally, fig. (13) shows the effect of case k on velocity, temperature, nu and st numbers for laminar flow (fig. (13-a to d)) and for turbulent flow (fig. (13-e to g)) where ( tin=10 co & twall=40 co ). fig. (13-a) indicates the temperature contours at ( z = 0.531 m ), the influence of the vortex pair is very clear. and the average nu has been presented in fig. (13-b) for the four-sided wall. it is clear that the roughened walls have a large value than the smooth walls. it can bee seen from this figure that the average nu for right and left walls starts out high and then gradually tapers off. this is to be expected as the thermal boundary layer develops within the duct. and for top finned wall, it can be seen that the fins result in higher average nu, it is also observed that the addition of the fins produces an oscillating shape in the curve of the nu along the duct. also for bottom-baffled wall, a higher nu is achieved. here, the baffle increases the local airflow velocity at the heated surface by reducing the cross-sectional area of the duct. the local nu for top wall with 4-fins and for bottom wall with wing-type vg are presented in fig. (13-c & d) respectively. high nu can be attributed to the fact that the turbulators are causing flow separation and reattachment, as well as interrupting the boundary layer, causing high turbulence local to the heated surface. the periodicity in fig. (13-b & c) can be attributed to the periodic placement of the fins and the fact that the flow separation is occurring before and after the fins. these points of separation result in local “hotspots”, which translate into a reduction in the nusselt numbers. fig. (13-e) at ( z = 1.68 m ) shows that for delta wing in a duct flow the divergence of the vortex axes prevails but the cross-section becomes strongly elliptic. the symmetry planes set limits to the possible divergence of the vortices, and the walls set limits to their vertical movement. fig. (13-f) illustrate the st for bottom wall with wing-type vg, it shows large fluctuations decreases with distance. fig. (13-g) shows the average nu for the four walls, the upper and lower roughened walls have a larger value than the right and left smooth walls. conclusions the following are been concluding from the present work: 1. longitudinal vortices of moderate size and strength have been found to cause a significant perturbation in the heat transfer behavior of an otherwise three-dimensional boundary layer. local st increases and decreases, resulting in a net increase in the span wise-averaged heat transfer coefficient or nu. 2. the use of a turbulence promoter can effectively improve the heat transfer characteristics and avoid the occurrence of hotspots in the high-temperature regime. in addition, it enhances not only the heat transfer performance of its downstream ribs, but also that of its upstream ribs. 3. when the side-wall confinement is appropriately utilized, most of the up wash sides of the longitudinal vortex pairs induced by the vgs arranged in a proper pitch can be truncated resulting in a large area of the vortex-generator mounted wall exposed to the downwash sides of the longitudinal vortex pairs and, in turn, high heat transfer augmentation. 4. the vgs are punched out of the fin and they generate swirling motion in the flows in the duct formed by the fin and thereby increase the heat transfer. 5. with the exception of the configurations, the addition of ribs always improved the average nu number. 6. combining ribs with baffles yielded an increase in average nu. therefore, a situation where rate of heat transfer is critical to the performance of a device combining ribs with baffle is a viable solution. fig. (1) types of vortex generators used (the figures not to scale): a) fins, b) vertical rib ,c) horizontal fin, and d) horizontal & vertical rib,e) vertical fins, and f) oblique rib ,g) staggered ribs, h) delta-winglet. fig. (1) continue: i) pair of winglets, j) multi-ribs, and k) wing & fins. table (1) duct and vgs configuration. case vg type configurations grid size re duct vg b (m) h (m) l (m) b (mm) h (mm) l (mm) β (o) α (o) laminar turbulent a staggered fins 0.32 0.16 0.8 48 24 -- 90 90 21*21*31 1,500 100,000 b vertical rib 0.16 0.08 0.6 32 80 16 90 90 11*19*40 750 7,500 c horizontal fin 0.16 0.08 0.6 160 5 -- 90 90 20*19*40 2,119 21,191 d horizontal and vertical ribs 0.4 0.2 1.68 horizontal 21*21*31 500 5,000 400 20 57 90 90 vertical 40 200 57 90 90 e staggered 2-fins 0.16 0.08 0.6 32 80 -- 90 90 11*19*40 750 7,502 f oblique rib 0.32 0.16 0.8 320 20 54 90 55.4 9*18*31 1,500 12,800 g broken ribs 0.32 0.16 0.8 50 16 27 90 90 21*21*31 2,000 10,000 h delta winglet 0.12 0.055 0.7 10 15 46 90 12 25*12*70 1,700 12,571 i 2-delta winglet 0.12 0.055 0.7 10 15 46 90 12 25*12*70 1,700 17,000 -12 j 5-continuous horizontal ribs 0.16 0.08 0.6 4-at bottom wall 90 90 11*19*50 750 14,222 160 13 12 last one 160 4 12 k delta wing with horizontal 4-fins 0.4 0.2 1.68 delta wing 26*15*60 1,000 5,000 144 157 316 26 90 4-fins 400 14 -- 90 90 ( a ) ( b ) fig. (2) secondary flow velocity vectors at z = 0.6 m (a) present result (b) data of [13]. ( a ) ( b ) fig. (3) variation of (w/win) at mid plane and re=100: (a) present result (b) result of [17]. ( a ) ( b ) ( c ) ( d ) fig.(4) variation of flow field and isothermal contour and nu for finned duct. re=1,500: (a) velocity vectors, (b) average nu, (c) local nu at upper wall, (d) temperature contours. ( e ) ( f ) fig.(4) continue , re=100,000: (e) isothermal contours, and (f) average nu. ( a ) ( b ) fig. (5) velocity vectors and nu for vertical ribbed duct. re=750: (a) velocity vectors in five selected planes, and (b) average nu on rib’s two surfaces. ( a ) ( b ) fig. (6) temperature contours and nu for case c. re=2,119: (a) temperature distributions, and (b) average nu. ( a ) ( b ) ( c ) ( d ) ( e ) ( f ) ( g ) fig. (7) temperature contours, nu, and velocity vectors for case d. re=500: (a) temperature distributions, (b) temperatures at (x-z) plane, (c) average nu for horizontal rib, (d) average nu for vertical rib, (e) local nu for vertical rib, re=5,000: (f) velocity vectors in (x-y) plane, (g) velocity vectors in (x-z) plane. ( a ) ( b ) fig. (8) velocities distributions for case e. re=750: (a) u/win , (b) v/win . ( a ) ( b ) ( c ) ( d ) ( e ) ( f ) fig. (9) nu variations, velocity vectors and temperature contours, for case f. re=1,500: (a) average nu, (b) local nu at bottom wall, re=12,800: (c) v contours, (d) w/win distribution, (e) isotherms, (f) average nu for turbulent case. ( a ) ( b ) ( c ) ( d ) ( e ) ( f ) fig. (10) nu variations and velocity vectors for case g. for laminar flow re=2,000: (a) velocity vectors, (b) local nu, (c) average nu, and for turbulent flow re=10,000: (d) velocity vectors, (e) local nu, (f) local stanton number. ( a ) ( b ) fig. (11) nu variations and velocity vectors for cases h & i. re=1,700: (a) local nu, re=17,000: (b) velocity vectors. ( a ) ( b ) ( c ) ( d ) fig. (12) velocity distributions, temperature contours, nu, and st numbers for case j. for laminar flow re=750: (a) velocity vectors, (b) temperature contours, (c) isotherms, (d) average nu. ( e ) ( f ) ( g ) fig. (12) continue, for turbulent flow re=14,222: (e) velocity (w) vectors, (f) average nu, (g) local st. ( a ) ( b ) fig. (13) velocity vectors, temperature contours, nu, and st numbers for case k. for laminar flow re=1,000: (a) temperature contours, (b) average nu. ( c ) ( d ) ( e ) ( f ) ( g ) fig. (13) continue, (c) local nu for top wall with ribs, (d) local nu for bottom wall with wing, for turbulent flow re=5,000: (e) velocity vectors, (f) local st for bottom wall with vg, (g) average nu with vg. nomenclature greek symbol coefficients in general finite-domain equation ae , aw inclination angle in (x-z) plane α wall area of the control volume acell angle of attack in (y-z) plane β width of the vg (wing span) b diffusion coefficient г width of the duct b rate of dissipation of k ε coefficient in turbulence models, =1.43, 1.92, 0.09 respectively c1ε,c2ε,cμ von karman’s constant κ specific heat cp dynamic viscosity μ diffusion terms de , dw kinematics viscosity υ logarithmic wall constant e fluid density ρ convection coefficients fe , fw prandtl number σ wall force fs wall shear stress τwall generation rate of turbulence energy g subscript vg height h effective value eff duct height h control volume faces e , w hydraulic diameter hd condition at inlet in turbulent kinetic energy k refer to turbulence model equation k , ε thermal conductivity of the fluid k laminar flow condition l vg length or thickness or chord l normal distance from a wall n duct length l duct dimensions = b , h , l n nusselt number nu central node and its neighbors ( east and west ) p , e , w pressure p turbulent flow condition t finite-domain cell peclet number pe condition at wall wall prandtl number pr superscript stanton number st dimensionless value + reynolds number re abbreviation temperature t elliptic equation solver for convection and heat transfer esceat bulk temperature tb two-equations turbulence model k-ε field reference temperature tref simi-implicit method for pressure linked equation simple mean velocity components u,v,w vortex generator vg coordinate directions x,y,z references 1jeffrey alan taylor, “ development of an ‘ active wing’ for the validation of active flow control schemes to be applied to the of incipient separation “, m.sc. thesis, mech.eng. , clarkson 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“a numerical study of vortex shedding from rectangles ”, j, fluid mech .(1982),vol.116,pp.475-506. 13p.a. eibeck and j.k. eaton ,” heat transfer effects of a longitudinal vortex embedded in a turbulent boundary layer”, transactions of the asme , journal of heat transfer , february 1987 ,vol.109 ,pp16-24 . 14-hayder mahdi kadhum,”numerical and experimental study of enhancement of heat transfer in roughened ribbed duct”, january 2004, ph.d. thesis, dept. of technical education, university of technology. 15waheed. s. mohammed,” space air-conditioning of mechanically ventilated rooms: computation of flow and heat transfer ”, june 1986,ph.d.thesis, school of mechanical engineering, cranfield institute of technology. 16patanker s.v.’numerical heat transfer and fluid flow ”, me graw-hill book company new york, 1980. 17sabah tarik ahmed,”numerical and experimental study on heat transfer enhancement by vortex generator ”, september 2001, ph.d. thesis, dept. of mechanical engineering, university of technology. تأثيرات انواع مولدات الدوامة على انتقال الحرارة وشكل الجريان في المجاري المستطيلة أ.م.د.وحيد شاتي محمد قسم هندسة المكائن والمعدات الجامعة التكنولوجية أ.م.د.صباح طارق احمد قسم هندسة المكائن والمعدات الجامعة التكنولوجية م.م.ليث جعفر حبيب قسم هندسة المكائن والمعدات الجامعة التكنولوجية الخلاصة: في هذه الدراسة النظرية تم حساب خصائص انتقال الحرارة وشكل الجريان لحالات الجريان الطباقي والاضطرابي خلال مجرى مستطيل يحوي مولدات دوامية مختلفة ولمدى واسع لرقم رينولدز من 500 الى 100,000 .حيث تم استخدام نسخة مطورة من برنامج (esceat) لحل معادلتي نفير-ستوك والطاقة .ان الغرض من البحث الحالي هو تقديم مقارنة عددية من ناحية درجة الحرارة ورقم نسلت وشكل الجريان لاشكال متنوعة من العوائق من ضمنها خمسة حالات. وتمت دراسة انتقال الحرارة وشكل الجريان من خلال كنتورات مركبات السرعة والدوامات وتغيرات درجات الحرارة ورقم نسلت. وقد اظهرت الدراسة ان الاشكال المتوقعة لجريان المائع ومجالات درجات الحرارة وتغير رقم نسلت تتأثر بشكل كبير بوجود مولدات الدوامات.ان ترتيب العوائق بشكل متعاقب يعطينا رقم نسلت عالي، كذلك ان ترتيبها بهذه الاشكال يعطينا رقم نسلت اعلى من حالة المجرى المسطح.كما ان لحالة رقم رينولدز عالي (سرعة دخول عالية للهواء) فان رقم نسلت سوف يتحسن.وان بزيادة ارتفاع العائق سوف يتحسن انتقال الحرارة بسبب عمل العائق كمساحة سطحية ومولد دوامة في نفس الوقت. كلمات المفتاح: مولدات دوامات cfd, انتقال الحرارة وجريان الموائع , المجاري المستطيلة d c � embed pbrush ��� 0,0,0 x z y b b h l b a z x y l g h e α h f i j β k w � s s w w e e f f b b n n y x z page 47 _1243498108.unknown _1243498350.unknown _1243498622.unknown _1243498829.unknown _1260821054.unknown _1243498847.unknown _1243498786.unknown _1243498541.unknown _1243498578.unknown _1243498380.unknown _1243498241.unknown _1243498308.unknown _1243498174.unknown _1243497692.unknown _1243498010.unknown _1243498081.unknown _1243497782.unknown _1243358381.unknown _1243497526.unknown _1243497614.unknown _1243496886.unknown _1214201259.unknown _1214201456.unknown _1213043827 _1214201146.unknown _1200349205.unknown _1173207870 summary al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 5, no. 4, pp 25-38 (2009) study the effect of hydrolysis variables on the production of soya proteins hydrolysis mohammed b. al-bahri * safa a.al-naimi ** sundus h.ahammed *** * department of biochemical engineering/ al-khwarizmi college of engineering/ university of baghdad ** department of chemical engineering/ university of technology *** ministry of sciences and technology (received 10 march 2008 ; accepted 25 march 2009) abstract this study was conducted to determine the effects of concentration of hydrochloric acids, temperature, and time on the hydrolysis of soya proteins (defatted soya flour) by determining the value of total protein nitrogen concentration, and amino nitrogen concentration of protein, peptides, and amino acids, and then calculated the hydrolysis rate of proteins. the variables of the conditions of hydrolysis process was achieved in this study with the following range value of tests parameter:  concentration of hcl solution ranged between 1-7 n,  hydrolysis temperature ranged between 35-95 c, and  the time of hydrolysis period ranged between 0.5-24 hr. experiments were designed according to the central composite rotatable design. the practical study has shown the possibility of decreasing the negative effect of the acid on the biological characteristics of the protein; then affecting the possibility of using the product for biological purposes (for medical and microbiological laboratories) by:  decreasing the acid concentration used in the process of hydrolysis, firstly, and  decreasing the temperature of the hydrolysis process, secondly, and then  increasing the period of the time of hydrolysis process, thirdly. keywords : acidic hydrolysis of soya proteins, acidic hydrolysis of soybeans proteins, acidic hydrolysis of vegetable proteins, proteins hydrolysis theory, methods of proteins hydrolysis. 1. introduction the hydrolysis of proteins, which breaks them down to their constituent amino acids and peptides, can be achieved by the use of strong acids, strong bases or proteolytic enzymes, there are three main methods of hydrolysis of proteins[1]. hydrolysis with strong mineral acid or base (chemical catalysts of biological reactions) is nonspecific, attacking all peptides bonds, degrading proteins and polypeptides to low chain length peptides and amino acids[1], and also produces a large number of fragments[2]. in this process all peptide bonds are attacked and in theory, complete break down into component parts could be obtained[1]. acid or base treatment of plant (soybean, corn) or animal (casein) proteins brings about desirable changes in flavor, texture, and solubility. such treatments also destroy toxins and trypsin inhibitors and are used to prepare protein isolates[3]. one of the principals advantages of acid as compared with base hydrolysis is that the optical activity of the amino acids is not destroyed in the process[4], on the other hand, acid hydrolysis destroys tryptophan and partially destroys cystine, serine, and threonine. asparagine and glutamine are converted to their acidic form[1][4], and a series of reaction may also take place between carbohydrates and amino acids (maillard reaction) which gives rise to very dark brown mohammed b. al-bahri al-khwarizmi engineering journal, vol. 5, no. 4, pp 25 -38 (2009) 26 decomposition products, called “humin” often toxic to the growth of microorganisms[4],[3]. partial hydrolysis of protein with acids or bases produces mixture of -amino acids, peptides, and polypeptides[5], as shown. ch c h n ch o c n h o ch c o h n ch h2o h + or oh amino acid units section of a protein chain mixture of polyeptides, peptides, andamino acids partial hydrolysis r''' r'' r' r but complete hydrolysis of proteins with acids or bases, produces mixtures of -amino acids as the principle products[5], as shown. ch c h n ch o c n h o ch c o h n ch h2o h + or oh amino acid units section of a protein chain mixture of amino acids complete hydrolysis r''' r'' r' r h2n c cooh r (r',r'',etc) h another method for hydrolysis of proteins by using proteolytic enzymes (biological catalysts) acts on proteins under less severe conditions, they will function at much lower temperatures, and at normal pressure and are usually specific to the peptide bond they will attack (1) . enzymes commonly used are pepsin, papain, and pancreat (1) , as shown in fig.(1). mohammed b. al-bahri al-khwarizmi engineering journal, vol. 5, no. 4, pp 25 -38 (2009) 27 fig.1. diagram of enzymatic action[1]. the hydrolysis of proteins, they are prepared by the enzymic or acidic hydrolysis of proteinaceous material. these hydrolysates contain secondary protein derivatives such as polypeptides, dipeptides and amino acids. they provide a readily assimilable source of nitrogen which is water soluble, does not coagulate on heating, and is therefore particularly suitable for inclusion in microbiological culture media[6]. the hydrolysis of a protein molecule is a gradual process by which the gigantic molecule of protein is converted in to products of successively lower molecular weight[7], hydrolysis proteins yield metaproteins, proteoses, peptones, polypeptides, and finally the chemically simpler amino acids and their analogs[8]. the degree (rate) of hydrolysis of proteins (dh %) is measured by the number of peptide bonds cut, divided by the total number of peptone bonds, multiplied by a hundred and is calculated by the formula of equation (1) [1]. dh% = [(an of hydrolysis protein – an of protein) / tn of protein] × 100 …(1) hydrolyzed vegetable protein is widely utilized in food production, the production of protein hydrolysate from plant proteins has been done using microbial fermentation. this process however, is slow and takes from 4 to 6 months to accomplish. the use of mineral acids reduces the time required to accomplish hydrolysis. these products made by acid hydrolysis are available in european, american, and japanese markets from1945[9]. the hydrolysis of protein samples as a function of time was studied by hirs, stein and moore (1954) who suggested corrections necessary for incomplete hydrolysis or for destruction of amino acids[10]. the hydrolysis of protein samples with acid was studied by pham and rosario (1983), they studied the preparation of protein hydrolysate from defatted coconut and soybean meal by determination of the effects of temperature, time, and concentration of acids on the hydrolysis of coconut and soybean meal, using 6 n hcl, the complete hydrolysis of soybean meal was reached after 36 hr at 95 c, while it took only 24 hr to complete the process when 18 n h2so4 was used at the same temperature. coconut protein exhibited some degree of resistance to hydrolysis, using 10 n hcl and 18n h2so4 in two separate tests, it took 48 hr to complete hydrolysis at 95 c [11],[12] . husein (1985) studied the hydrolysis of protein from soya grits and dehydrated alfalfa flour by hcl hydrolysis. protein was added with 33% hcl in a 1:1 ratio by weight, the conditions of protein hydrolysis was mohammed b. al-bahri al-khwarizmi engineering journal, vol. 5, no. 4, pp 25 -38 (2009) 28 in a reactor with 130 c, 2.5 atm , for 4 hr [13].on the other hand, al-aaragi (1994) treated sample of soybean flour with 6 n hcl at 110 c in an evacuated tube for 24 hr, to determine the amino acid composition of soya proteins , above conditions, it is necessary to complete hydrolysis of soybean protein according to toffer procedure for analysis[14]. davies (1995), studied the conversion of protein to free amino acid form by treatment the protein with high concentration of acid (5m hcl) and high temperature (105c103c),and he studied the effect of these variables on the production of free amino acids[15]. 2. materials and methods 2.1 experimental design and experimental trials box-wilson composite rotatable design is a common type of statistical experiment especially applicable to optimization analysis (16),(17),(18) , therefore, experiments were designed according to the central composite rotatable design (boxwilson composite rotatable design), to can be achieved the purpose of this study . the study was devoted to test the effect of process variables on the rate of hydrolysis of soya protein; the experimental work was designed for the above purpose in the following experimental operating ranges: variable1:concentration of hcl solution ranging between 1-7 n. variable2:operating temperature of hydrolysis ranging between 35-95 c. variable3:duration time of specimen ranging between 0.5-24 hr. response function was rate of hydrolysis dh%. the center composite rotatable design of three variables was used. a preliminary step is the setup of the relationships between coded levels, and the corresponding real levels, as following: 1.732 4c x1   …(2) 17.321 65t x2   …(3) 6.784 12.25t x3   …(4) the working ranges of coded and corresponding real variables are listed in table (1). table 1, working range of the coded and corresponding real variables. coded level concentration of hcl solution in n operating temperature inc duration time in hr -1.732 1 35 0.5 -1 2.268 47.679 5.466 0 4 65 12.25 +1 5.732 82.321 19.034 +1.732 7 95 24 according to experimental design of the three variables there are twenty experiments (there are fifteen tests, and five tests are added at the center), were carried out in the sequence as listed in table (2), where the coded values of +1.732,-1.732,0 represent the maximum, minimum and average values, respectively. according to the central composite rotatable design of the experimental work, it explains the relationship between concentration of hcl solution, temperature, and time of hydrolysis of soya proteins, and effect of these variables on the hydrolysis rate of soya proteins, as well as, it studies the relationship between the rate of hydrolysis of soya proteins and tn, an, an/tn% ratio of hydrolysized product of soya proteins. mohammed b. al-bahri al-khwarizmi engineering journal, vol. 5, no. 4, pp 25 -38 (2009) 29 table 2, sequence of experiments according to central composite design. exp. no. coded variable real variable x1 x2 x3 c (n) t (c) t (hr) 1 -1 -1 -1 2.268 47.679 5.466 2 +1 -1 -1 5.732 47.679 5.466 3 -1 +1 -1 2.268 82.321 5.466 4 -1 -1 +1 2.268 47.679 19.034 5 +1 +1 -1 5.732 82.321 5.466 6 +1 -1 +1 5.732 47.679 19.034 7 -1 +1 +1 2.268 82.321 19.034 8 +1 +1 +1 5.732 82.321 19.034 9 -1.732 0 0 1 65 12.25 10 +1.732 0 0 7 65 12.25 11 0 -1.732 0 4 35 12.25 12 0 +1.732 0 4 95 12.25 13 0 0 -1.732 4 65 0.5 14 0 0 +1.732 4 65 24 15 0 0 0 4 65 12.25 16 0 0 0 4 65 12.25 17 0 0 0 4 65 12.25 18 0 0 0 4 65 12.25 19 0 0 0 4 65 12.25 20 0 0 0 4 65 12.25 2.2 experimental work experimental work includes mainly two principal stages, which are: first stage: includes necessary steps for preparation of defatted soya flour from dehulled and defatted soybeans, by using whole mature seed of lee class of soybean provided by ipa center for agricultural researches (iraq). at the beginning, moisture must be removed from the seeds of soybeans to facilitate the following processes of removing the hulls and of grinding. the main purpose of removing the hulls is to get rid of the soil attached to them. besides that, their compositions contain a high degree percent of fibers. accordingly, this will affect the quality of the product. the purpose of the next step is to remove the oil completely from the soya flour. at the same time the quality of the removed oil must be reserved from any destruction that may take place because of the conditions of the process of extraction, to avoid the destruction of soybeans fat , the process of fat removal from the soybeans flour has been done in three stage . after the process of removing the fat, the soybeans flour is re-grinded to the size of 100 mesh which represents the stage of excessive grinding. then, the defatted soya flour will be ready for the next stage. defatted soya flour was prepared by drying the beans at 68°c for 8 hr, and dehulling them. the dehulled beans were ground to pass through a 60 mesh sieve (first milling process)[11]. oil was extracted with hexane in three stages[19], and then the solvent was removed from flour[19]. the sample flour obtained after milling were passed through a 100 mesh sieve (second milling process), packed in plastic bags , and stored at 10°c[11]. second stage: according to the central composite rotatable design, table (2), twenty trials were done on each run, the analysis was done for each trial, using the following procedure: mohammed b. al-bahri al-khwarizmi engineering journal, vol. 5, no. 4, pp 25 -38 (2009) 30 hydrochloric acid solution of each concentration was added to sample of defatted soya flour in a glass beaker, and stirred by a mechanical stirrer (the ratio of defatted soya flour to hcl solution was 1:3 (w:v)) [20]. the temperature of hydrolysize was controlled in the water bath, also the glass beaker was covered by using silver paper. after finishing each trial, the hydrolysized product was cooled directly to 25 c, and then it was neutralized by sodium hydroxide solution. the volume of neutralized hydrolyzed product was modified to a constant volume for all trials by adding deionized water, and then it was filtered through whatman filter paper no.541, filtration was carried out under vacuum [11],[12]. after that, the filtrate volume was modified to a constant volume for all trials, after that, the final filtrate volume was used to determine tn, an, and an/tn%. 2.3 methods of analysis  protein was determined by using the absolute method[21].  total protein nitrogen of samples was determined by using 5.71 factor to convert amount of protein to total protein nitrogen tn[19].  amino nitrogen was determined by using formaldehyde titration method[1],[22].  moisture was determined by using the air oven method[22],[23].  oil was determined by using intermitted extraction method[23].  ash was determined by using dry ashing method[22],[23].  fiber was determined by using the procedure of fertilisers and feeding stuffs regulations 1976 si no. 840[23].  carbohydrate percentage was determined by subtracting all other components form 100% percent [23]. 3. results and discussion first stage: the main purpose of the procedure followed in this stage is to prepare the defatted soya flour to be ready for carrying out the laboratory experiments. after finishing this stage, the defatted soya flour will be ready for the next stage. the chemical analysis of soybeans during the stages of preparing the defatted soya flour, can be shown in table (3). table 3, chemical analysis of soybeans during the stages of preparing the defatted soya flour. chemical compositions the degree percent of the chemical compositions (w/w%) soybeans dried soybeans dehulled soybeans defatted soybeans first stage second stage third stage moisture 6.856 2.321 2.352 2.887 3.001 3.048 protein 35.412 37.136 39.932 49.011 50.941 51.733 oil 20.235 21.22 22.811 5.262 1.531 ash 5.634 5.908 5.862 7.195 7.478 7.594 fiber 5.375 5.637 1.544 1.896 1.97 2.001 carbohydrate 26.488 27.778 27.499 33.749 35.079 35.624 second stage: the results of the carried out experiments according to the experimental design of box wilson are shown in table(4). to find out the relation between the dh% and the effect of the following variables on the process of protein hydrolysis: concentration of acid, temperature and the duration of the process of hydrolysis, the conditions of each experiment were fed into a computer program (statistical program). these conditions were entered according to the significance of coded variable and the degree of hydrolysis, which were prepared according to the experimental design shown in table (4). this process is done to get the coefficients of the polynomial equation of the second order. the resultant equation is as follows: dh% = 44.80638 + 13.33998 x1 + 11.94455 x2 + 10.64997 x3 + 0.1561251 x1 2 + 3.631374 x2 2 + mohammed b. al-bahri al-khwarizmi engineering journal, vol. 5, no. 4, pp 25 -38 (2009) 31 2.702626 x3 2 2.655856 x1x2 2.8462 x1x3 2.66819 x2x3 …(5) average error = 3.584888% correlation coefficient = 0.9945404 standard deviation = 1.892087 equation (5) has been figured to clarify the effect of each of (c), (t), and (t) on (dh%) by means of figures (2), (3), (4) and (5). table 4, results of experiments planned according to composite rotatable design. exp. no. hydrolysized product tn gm/100ml an gm/100ml an/tn % dh % 1 0.647 0.10613 16.403 8.629 2 0.76967 0.28075 36.477 25.494 3 0.74497 0.2884 38.713 26.233 4 0.70441 0.18455 26.199 16.203 5 0.79686 0.46992 58.971 43.763 6 0.88121 0.51 57.875 47.634 7 0.79826 0.47918 60.028 44.658 8 0.99922 0.81068 81.131 76.673 9 0.61249 0.13901 22.696 11.805 10 0.99257 0.67056 67.558 63.141 11 0.65014 0.17812 27.397 15.582 12 0.87897 0.61963 70.495 58.222 13 0.65997 0.201 30.456 17.792 14 0.85299 0.6078 71.255 57.08 15 0.81341 0.47839 58.813 44.581 16 0.88961 0.47053 52.892 43.822 17 0.88111 0.48393 54.923 45.117 18 0.78502 0.49002 62.421 45.705 19 0.87397 0.47712 54.592 44.459 20 0.79628 0.48432 60.823 45.154 mohammed b. al-bahri al-khwarizmi engineering journal, vol. 5, no. 4, pp 25 -38 (2009) 32 fig. 3. degree of hydrolysis as a function of time (hr) at 65 c. 0.000 6.000 12.000 18.000 24.000 30.000 time ( hr ) 0.000 20.000 40.000 60.000 80.000 100.000 d e g r e e o f h y d r o l y s is ( d h % ) 7 n 5.732 n 4 n 2.268 n 1 n fig. 2. degree of hydrolysis as a function of temperature (c) at 12.25 hr. 0.000 20.000 40.000 60.000 80.000 100.000 temperature ( c o ) 0.000 20.000 40.000 60.000 80.000 100.000 d e g r e e o f h y d r o l y s is ( d h % ) 7 n 5.732 n 4 n 2.268 n 1 n mohammed b. al-bahri al-khwarizmi engineering journal, vol. 5, no. 4, pp 25 -38 (2009) 33 3.1 effect of acid on protein hydrolysis 1. breaking down some of the amino acids, completely and breaking down some other amino-acids partially. 2. converting some of the amino acids to the acidic formula. 3. improving the reactions between the carbohydrates and proteins (malliard reaction) that leads to making poisonous materials. 4. nacl salt will result (as chemical material in the final product) from the reaction of hcl and naoh when neutralizing the hydrolyzed product. the first and second effects occur under all the condition of the process of hydrolysis since the acid is a catalyst for this process. from al– aaraji result (10) about lee class of soybeans, the degree percent of amino acids that break down completely and partially and amino acids that are fig. 4. degree of hydrolysis as a function of time (hr) at 4 n. 0.000 6.000 12.000 18.000 24.000 30.000 time ( hr ) 0.000 20.000 40.000 60.000 80.000 100.000 d e g r e e o f h y d r o l y s is ( d h % ) 95 c o 82.321 c o 65 c o 47.679 c o 35 c o 0.000 2.000 4.000 6.000 8.000 hcl concentration ( n ) 0.000 20.000 40.000 60.000 80.000 100.000 d e g r e e o f h y d r o l y s is ( d h % ) 95 c o 82.321 c o 65 c o 47.679 c o 35 c o fig. 5. degree of hydrolysis as a function of hcl concentration (n) at 12.25 hr. mohammed b. al-bahri al-khwarizmi engineering journal, vol. 5, no. 4, pp 25 -38 (2009) 34 converted into the acidic formula , which have a very little degree percent in comparison with other amino acids that constitute of soybean protein. therefore, the side-effects of the first and second effects can be neglected. with regard to the third effect of treating the protein by the acid, this reaction can not be prevented assertively, even in the lowest conditions, yet the occurrence of this reaction could decreased by depending on the intensity of the conditions. the fourth effect of using the acid hcl in the process of hydrolysis is producing nacl , a case which can not be prevented, but may be reduced as much as possible by using low concentrations of the acid. however, less amounts of salt obtained when neutralizing the hydrolysizd product. 3.2 effect of temperature temperature greatly affects on the process of protein hydrolysis. by increasing the temperature, protein hydrolysis degree increases. this effect follows the effect of acid concentration on protein hydrolysis. the direct effect lies in increasing the rate of the protein molecules digest reaction, whereas the indirect effect causes increasing in the acidic efficiency. on the other hand, the negative effect of temperature on the process of protein hydrolysis appears directly through its help in the occurrence of malliard reaction at high degree accompanied by high temperature. 3.3 effect of time importance of time effect on the process of protein hydrolysis comes after the effect of both the concentration of the acid and temperature. time is considered nearly to be the only factor that has a positive effect on the protein hydrolysis. it also retains its biological characteristics in comparison with the effect of both the concentration of the acid and temperature when digesting the protein by the acid. therefore, if the product of protein digest process is wanted to be used for biological purposes, it is necessary to make use of time factor before that of the concentration of acid and temperature. this is because the hydrolysized product has good biological characteristic in spite of the occurrence of malliard reaction with somehow little degree. 3.4 studying the mathematical relationships and figures the relationship between each of tn, an, and tn/an% for the hydrolysized product with the degree percent of protein hydrolysis dh% are shown in the figures (6), (7), and (8).the results predicted from figures (6), (7) and (8), are concluded in table (5). 0.000 20.000 40.000 60.000 80.000 100.000 degree of hydrolysis ( dh % ) 0.50000 0.60000 0.70000 0.80000 0.90000 1.00000 1.10000 t o t a l n it r o g e n ( t n ) ( g m / 1 0 0 m l ) fig. 6. tn concentration of hydrolysized product as a function of dh%. mohammed b. al-bahri al-khwarizmi engineering journal, vol. 5, no. 4, pp 25 -38 (2009) 35 table 5, equations concluded from figures (6), (7), and (8). no. of fig. equation average error % kind of relationship the extent of application 6 tn(gm/100ml)=0.5773207511+ 5.844792489e-3 (dh%) …(6) 4.412 linear relationship 100dh%0  7 an(gm/100ml)=0.01678+ 0.0103543(dh%) … (7) 0.81 linear relationship 100dh%0  8 an/tn%=5.653779+1.437379 (dh%) 6.345795e-3(dh%) 2 …(8) 4.506 non linear relationship 76.673dh%8.629  fig. 8. an/tn% of hydrolysized product as a function of dh%. 0.000 20.000 40.000 60.000 80.000 100.000 degree of hydrolysis ( dh % ) 10.000 20.000 30.000 40.000 50.000 60.000 70.000 80.000 90.000 ( a n / t n ) % fig. 7. an concentration of hydrolysized product as a function of dh%. 0.000 20.000 40.000 60.000 80.000 100.000 degree of hydrolysis ( dh % ) 0.00000 0.20000 0.40000 0.60000 0.80000 1.00000 a m in o n it r o g e n ( a n ) ( g m / 1 0 0 m l ) mohammed b. al-bahri al-khwarizmi engineering journal, vol. 5, no. 4, pp 25 -38 (2009) 36 the linear relationship between tn and dh% shown in equation (6) and figure (6) gives values approaching the real values of tn when the protein hydrolysis degree is low; whereas the inaccuracy of the tn values (obtained from this equation) increases in comparison with the real values of tn wherever the protein hydrolysis degree increases, because of the increase in the weight of the protein resulting from the process of digest (from the water molecule which replaces each broken bond of peptides bonds, consists of proteins molecule ). with regard to equation (7), a new formula is reformulated from the linear equation (1) where the protein hydrolysis degree has been calculated after limiting the an . hence, all the points resulted from the above equation lie on one straight line as shown in figure (7). equation (8) clarifies relationship a non-linear between dh% and an/tn% as shown in figure (8), which, in its turn, is correct only at dh% extent of application ranging between 8.629% and 76.673%, it is concluded that whenever the protein hydrolysis degree increases, the an/tn% value also increases. this approached to 100% with the increasing the protein hydrolysis degree to100%. 4. conclusions  the side effect of the acid on the protein can be decreased by dealing with low acid concentrations in the first place and then temperature.  a middle degree of protein dissolving can be obtained under low conditions with regard to acid concentration and temperature but in a long time, whereas, the same dissolving can be get but within a short time by increasing the acid concentration and temperature. yet, the difference between these two cases lies in that, in the first case the rate of the malliard reaction between the carbohydrates and proteins is less. the opposite occurs with the second case. therefore, the product of the first case will be suitable in biological uses, in contrary with that of the second case. 5. abbreviations dh% degree of protein hydrolysis tn concentration of total protein nitrogen an concentration of amino nitrogen of protein, peptides, and amino acids c concentration of hydrochloric acid solution in normality (n) t operation temperature in c t duration time of specimen in hr x1 concentration coded variable x2 temperature coded variable x3 time coded variable 6. acknowledgments the authors thank the department of chemical engineering / university of technology, and the ministry of industry and minerals for their help in providing facilities, during the period of achieving this work 7. references [1] bridson, e.y., “the oxoid manual”, 7 th ed., united kingdom,(1995). [2] weininger, s. j., stermitz, “organic chemistry”, international edition, (1984). [3] friedman, m., and r. liardon, j. agric. food chem., 33, 666, (1985). [4] haurowitz, f., “biochemistry”, an introductory textbook, john wiley & sons, inc., new york, (1955). [5] hendrickson, j. b., d. j. cram, and g. s. hammond, “organic chemistry”, 3rd ed., international student edition, mcgraw-hill kogakusha, ltd., (1970). [6] “the oxoid manual”, united kingdom, (1988). [7] brewster, r. q, and w. e. mcewen, “organic chemistry”, 3rd ed., (1958). [8] “difco manual of dehydrated culture media and reagents for microbiological and clinical laboratory procedures”, 9th ed., detroit l, michigan, u.s.a., (1964). [9] minor, l. j., j. fd. ind., 47, 758, (1945). [10] hirs, c. h. w., w. h. stein, and s. moore, j. biol. chem., 211, 941, (1954). [11] pham, c. b., and r. r. d. rosario, j. fd. technol., 18, 21, (1983). [12] pham, c. b., and r. r. d. rosario, j. fd. technol., 18, 163, (1983). [13] dzanic, h., i. mujic, and v. s. hack, j agric. food chem., 33, 683, (1985). mohammed b. al-bahri al-khwarizmi engineering journal, vol. 5, no. 4, pp 25 -38 (2009) 37 [14] al-aaraji ,s. b., m.sc. thesis, university of baghdad, (1994). [15] davies, j. s., “amino acids, peptides and proteins”, a review of the literature published during 1995, the royal society of chemistry, (1995). [16] cochran, w. g., and g. m. cox, “experimental design”, john wiley and sons, inc., new york, (1957). [17] montgomery, d. c., “design and analysis of experiments”, john wily and sons, new york, (1976). [18] perry’s, r. h., and c. h. chilton, “chemical engineers handbook”, mcgrawhill, 5th ed., (1973). [19] apostolatos, g., j. fd. technol., 19, 639, (1984). [20] metwalli, n. h., s. i. shalabi, a. s. zahran, and o.el demerdash , j. fd. technol., 17, 71, (1982). [21] whitaler, j. r., and p. e. granum, anal. biochem., 109, 156, (1980). [22] “aoac-official methods of analysis”, 12th ed., association of official agricultural chemists, washington d. c. (1975). [23] lees, r., “food analysis: analytical and quality control methods for the food manufacturer, and buyer”, 3 rd ed., leonard hill book, (1975). 38 -25، صفحة 4، العدد 5 مجلة الخوارزمي الهندسية المجلد محمد باسل علي غالب البحري (2009) 38 دراسة تأثٍر متغٍرات عملٍة التمًٍء على إنتاج بروتٍن الصوٌا المتمٍئ محمذ باسل علً غالب البحري * صفاء الذٌن عبذ هللا النعٍمً ** حمذأ سنذس حمٍذ *** .جايعت بغذاد/ كهٍت هُذست انخىاسصيً/ اإلحٍائٍت قسى انهُذست انكًٍٍائٍت * .انجايعت انخكُىنىجٍت/ قسى انهُذست انكًٍٍاوٌت ** .وصاسة انعهىو و انخكُىنىجٍا *** الخالصة حشكٍض يحهىل حايط انهٍذسوكهىسٌك، دسجت انحشاسة، وانضيٍ عهى عًهٍت حًًٍء بشوحٍٍ انصىٌا كم يٍحى أَجاص هزِ انذساست ألجم ححذٌذ حأثٍش االيٍُى َاٌخشوجٍٍ نهبشوحٍٍ وانسالسم انببخٍذٌت حشكٍضو انُاٌخشوجٍٍ انكهً نهبشوحٍٍ، حشكٍضبىاسطت ححذٌذ قًٍت كم يٍ (طحٍٍ انصىٌا يضال انذهٍ ) . واألحًاض االيٍٍُت، وعُذ أرٌ ٌخى حساب دسجت حًًٍء انبشوحٍٍ :يخغٍشاث ظشوف عًهٍت انخًٍئ أَجضث فً هزِ انذساست يع انقٍى انًخباٌُت انخانٍت نهًخغٍشاث انًخخبشة  حشكٍض يحهىلhcl ٍٍع،7-1 ٌخشاوح ب  ٍٍو95-35دسجت حشاسة انخًٍئ حخشاوح ب oو ،  ٍٍساعت 24-0.5صيٍ فخشة عًهٍت انخًٍئ ٌخشاوح ب . (. central composite rotatable design)و انخجاسب باسخخذاو طشٌقت يحى حصى بٍُج انذساست انعًهٍت إنى إيكاٍَت انخقهٍم يٍ حأثٍش انحايط انسهبً عهى انًىاصفاث انحٍىٌت نهبشوحٍٍ عُذ انخًًٍء انحايضً، وبانخانً إيكاٍَت اسخخذاو : بىاسطت (نالسخعًال فً انًخخبشاث انخحهٍهٍت انطبٍت وانًاٌكشوباٌىنىجٍت )انًُخج نإلغشاض انباٌىنىجٍت  حقهٍم حشكٍض انحايط انًسخخذو فً عًهٍت انخًًٍء، أوال، و  حقهٍم دسجت حشاسة انخًًٍء، ثاٍَا، و  نفخشة عًهٍت انخًًٍء، ثانثاصٌادة انضيٍ انالصو . <4d6963726f736f667420576f7264202d20d6cdec20e6cf20c7cde3cf20d2edcfc7e4> al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 16, no. 1, march, (2020) p. p. 4254 improving reverse engineering processes by using articulated arm coordinate measuring machine dhuha mohammed mahmood* ahmed zaidan mahmood** *,**department of automated manufacturing engineering / alkhwarizmi college of engineering/ university of baghdad/ baghdad/ iraq *email: duhamohammed55@gmail.com **email: ahmadhzaam@yahoo.com (received 25 september 2019; accepted 9 february 2020) https://doi.org/10.22153/kej.2020.02.001 abstract the invention relates to a coordinate measuring machine (cmm) for determining a measuring position of a probe. the aacmm is depends on the robot kinematics (forward and reverse) in their measurement principle, i.e., using the aacmm links and joint angles to determine the exact workspace or part coordinates. hence, the measurements are obtained using an aacmm will be extremely accurate and precise since that is merely dependent on rigid structural parameters and the only source of measurement error is due to human operators. in this paper, a new aacmm design was proposed. the new aacmm design addresses common issues such as solving the complex kinematics, overcoming the workspace limitation, avoiding singularity, and eliminating the effects of design error by designing a new and compatible aacmm that will incorporate all affective design factors into consideration. different types of design factors and limitations, which significantly affect the aacmm production fabrication processes, and ultimately. accuracy are given. cost and time factors effects on the design and manufacturing are found to be the most significant. two primary manufacturing techniques were used, both of which relied on rigors cad/cam iterations resulting in an entirely usable g-code. those methods are cnc and 3d printing, the most widely used methods in any industry. nevertheless, accuracy and ergonomics factors must be considered for precise measurements. the design was validated through various methods, such as the use of finite element measurement techniques, to make sure that the design was structurally correct. keywords: aacmm, robotic kinematics, g-code, cad/cam. 1. introduction the novel design of the aacmm is discussed in the following, including the design of the electric/electronic circuitry and the control model. the design concept was based on the three-axis robotic arm that will serve as the primary tool to obtain the required coordinates measurements. this was to utilize the kinematic model to obtain the measurements with ease. the complete forward and reverse kinematic modeling resulted in the following governing equations, where both q1 and q2 represent the aacmm joint angles needed to reach any point within the machine workspace, �� � � tan 2 ��1 � ��������������������� �� ‚ �������������������� � …(1) �� � � tan 2 ⎝ ⎛��1 � ��������� � ! "�#����� !$% "�������� �� ‚ �������� � ! "�#����� !$% "�������� ⎠ ⎞ …(2) where, �� and �� are the arm joint angles calculated by the rotary encoders and resolved using the algorithm. (), (*, and (+ are the corresponding positions of the workpiece dhuha mohammed mahmood al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 4254 (2020) 43 geometrical points, ,� & ,� are the arm links length. this model is useful and can be used with no further complications. the design process had several constraints that needed deep consideration as can be seen in figure 1, namely: cost, time, size, manufacturing method, and programming environment [1]. fig.1. cmm design constraints. the cost was the first limiting factor, where everything had to be designed around that constraint. also it is a known fact that this work had a minimal budget. the second factor is time, where the work and design activities associated with it had to be accomplished within a very tight time window [2]. the choice of manufacturing technique was a challenge, since all the options available were all dependent on the first two constraints, cost and time. lastly, the choice of the programming environment was a significant consideration. this factor will untimely affect the choice of some of the most critical hardware components of the cmm, which is the controller. this choice is then connected to and affected by the other design constraints, all of these constraints, as illustrated in figure 1. as with all articulated arm cmms (aa-cmms) [3]. the position of the probe may be controlled manually by the operator or maybe controlled by the computer. the aa-cmm agile development cycle is illustrated in figure (2). fig. 2. the aa-cmm agile development cycle. to create cad sketches, solidworks was used. to creating accurate 2d drawings. where can be automatically updated on-the-fly, especially with agile development, when changes to 3d models are expected. moreover, solidworks offers comparison capabilities of design against real-world conditions to ensure the achievement of the best design before building it [4]. dhuha mohammed mahmood al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 4254 (2020) 44 fig. 3. coordinate measuring machine device design and manufacturing process flow. 2. aacmm part design a coordinate measuring machine (cmm) device is composed of the structure of transparent and transparent acrylic material, consisting of a base which is the leading platform of the device where the part to be examined and drive it to a three-dimensional model, two arms and a rotary joint. each unit is connected mechanically and electrically with other units in an electronic system to make the desired device. each unit is basically a control system to find out the juxtapositions and dimensions of the material to be examined, and the device is operated using the controlled with arduino uno. 2.1 mechanical components as mentioned before, the aacmm consists of two categories, leading and supporting. 2.1 a. main components 1. the base the base can be described as a rectangular table, which is used as a base for the part to be measured and will be holding the main arm as well. therefore, it has a circular pattern to hold the base rings, and ultimately the arm-probe assembly. each (bolt hole) with a radius of 0.04cm, with six holes to ensure that the base will be able to hold the arm-probe assembly, along with the supporting components and the encoders. the base design is shown in figure (4). the base will be stationed on four “stand” to provide some elevation from the ground and to make sure that the work surface will be isolated from its surroundings. the base dimensions are designed 21cm length and 18cm width, and 1 cm thickness. the larger the dimensions, the larger the object to be measured will be. however, the other components will have to be increased accordingly, all of which will increase the cost, manufacturing dhuha mohammed mahmood al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 4254 (2020) 45 time, and other constraints that had to be adhered to during the design process. fig. 4. design of the cmm base. 2. arm the arm is the second of the main component’s category. the primary function of the main arm is to serve as the link connecting between the base joint and the shoulder joint (2nd joint). this, of course, means that the main arm will play a significant role in the kinematic model calculations and the resulting aacmm measurements. the arm will be 3d printed, which keep the design simple, minimalistic, and to the point. figure (5) shows the arm design. the arm dimensions are 19cm length, 2cm width, and 1cm thickness. each end contains three bolt holes for the join encoders. 3. the probe arm the third component in this category is the probe arm. it is the most crucial part of the aacmm since it has two primary functions. the first, as the case with the main arm, it will act as the second link in the robotic arm joint-link assembly, providing all the remaining information for the kinematic model calculations. the second function is to act as the “touch” probe for the aacmm, which will be vital in the coordinate measurement process. figure (5) shows the probe arm design. where the arm length is 19cm with a 2cm touch point. dhuha mohammed mahmood al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 4254 (2020) 46 fig. 5. cmm probe arm. 2.1 b) supporting components the support equipment plays an important role, as well. they provide the geometric integration between the robotic arm link-join assemblies and allow the aacmm to function as it’s supposed to. the support equipment includes positioning base, base rings, flanges, spacers, and washers as shown in figure (6). fig 6. a. aacmm base ring. b. aacmm base. dhuha mohammed mahmood al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 4254 (2020) 47 3. the aacmm complete assembly in solid works now that all the components have been designed according to the concept specifications, the next step is to assemble all the components to create the aacmm final design. utilizing the assembly drawings feature in solidworks, it is possible to assemble the aacmm part by part to create the final layout as shown in figure (7). the “mate” function in solidworks is vital in ensuring that the aacmm link-joint assembly is correct, and the “motion study” function verified that the design would work as required. all of these verifications were done in solidworks, and it gave the “green light” to go ahead with the manufacturing process. fig. 7. articulated arm coordinate measuring machine aacmm after assembly. 4. control components the aacmm control components include the optical encoders, to capture the joints angular position, and the control board (arduino uno, shown in figure 8) will be used to translate the encoder's signal into actual measurements with the help of the control interface and the control program. electrical yield in digital structure relating to the angular position of the info. fig. 8. a. optical encoder. b. arduino controller. 5. working concept as mentioned earlier, optical encoders (rotary encoder) was used to convert the angular position or motion of the device joints to a digital output signal. in this work, four rotary encoders were used. the first was installed between the circular platforms, the second between the first arm and the rotating base, the third between the first arm, and the second and the last rotary encoder was installed between the base of the first arm and the table. the circuit schematic is shown in figure (9). dhuha mohammed mahmood al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 4254 (2020) 48 fig. 9. controller circuit schematic. all encoders are transmitted via an electronic circuit controlled by the arduino uno. as it's known, the encoder possesses two outputs a and b. if a operates before b, the rotation is to the right and if the opposite is to the left. the speed of operation is relative to the speed at which the object moves (the rotation speed of the table). the interval between a and b is the distance from which a and b are moved. number a and b represent the number of pulses transmitted. where the number of a and b of the most critical specifications of the encoder. in this work, each cycle gives 200 pulses to the arduino. when moving the arduino's arm receives 200 pulses, the pulses of the four encoders are grouped with equations after the pulses are converted into distances. the probe tip diverted from the base of the arms, using equations, thus determining the position of the tip using the reverse kinematic. when knowing the location of the tip of the robot. the coordinates of the tip of the robot are sent to the software that is stored in the processing program. it was programmed in c ++ to control the coordinates programmatically via the computer with six buttons programmed shown in figure (10): 1button (q) scans and adds all the points recorded on the interface. 2button (p) draws a point at that location. 3button (c) draws a circle at that location. 4button (f) draws a rectangle at that location. 5button (m) adjusts the coordinates in the case of moving the figure. 6button (z) stores the shape drawn by the user in the form of xyz, where it can be reopened by editing programs to adjust and mislead to the clarity of the shape drawn. 6. software components programming for the device was accomplished by combining two types of programming. the first was to convert the pulses that received from the movement of the first, second, third and fourth. pulses meet using equations, and pulses are converted to distances and by geometric equations are converted in to ratios after the head from the base where the head movement is converted to any location within the workspace. this is translated to a pulse to the arduino where it is recorded, and then sent the location of the head coordinates (x 'y' g) to the program processing where it decides whether the user of the device pressing the button draw point or the user did not press that button. e0 e1 e2 e3 dhuha mohammed mahmood al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 4254 (2020) 49 fig. 10. aacmm programming. 7. steps to manufacture the machine by cnc machine the aacmm is manufactured by a cnc laser machine. the code for the work was done by the program sold works and experimented with the program to be transferred to the machine to be cut and drilling using it as shown in the figure below fig. (11). fig. 11. solidworks cam cnc manager. dhuha mohammed mahmood al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 4254 (2020) 50 8. building the aacmm kinematic structure (implementation of aaccm) the subsequent stage is to choose the detail of each connection, joint, and the base. the structure of the aacmm is implemented with plexiglass sheets so as to diminish the general load of the aacmm. the plexiglass sheets are additionally sufficiently able to keep and hold the entire parts firmly together. the arm is connected to a base, which is the base piece of the aacmm. the base should have an extensively substantial load so as to keep up the general equalization of the aacmm in the event of estimating the various elements of an item. in spite of the fact that utilizing joins and optical encoders are splendid, however physical development of the aacmm is finished by utilizing manual movement as shown in figure (12). fig. 12. simulation of aacmm in solid works. to fabricate the aacmm parts rapidly, several factors had to be studied, including the limiting factors discussed previously in the design process. based on those reasons, the fabrication process started with the preparation and cutting of the rotating aacmm base, which will allow the user to be able to rotate the work part. the finished part is shown in figure (13) below. fig. 13. cnc laser machine. next, the aacmm arms (links) were manufactured. those are the most vital parts of the measurement process since they will determine the accuracy of the kinematic model and the resulting measurements. figures (14) and (15) shows the final design of both parts. fig. 14. the main arm. fig. 15. the arm probe. it should be mentioned that these two parts went through several design-fabrication cycles to bring their characteristics to the supposed and required criteria. those changes include the fact that the design had to be altered in connection to the work environment. the second modification dhuha mohammed mahmood al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 4254 (2020) 51 required that the weight of the two parts to reduced, design outcomes can be seen in figure (16) below. fig. 16. the manufactured aacmm arms. it was necessary to incorporate the new changes to bring these parts to their ultimate design requirements. the steps are illustrated in figures (17), and (18). fig. 17. the machined parts. fig. 18. fabricated the two arm. other components had to be 3d printed, such as the base legs, the arm fixtures pulleys, and the support rings. the support rings play an important role in providing the aacmm with the geometric integrity to fulfill the kinematic structure and kinematic model requirements. those are shown in figure (19). fig. 19. the progress of the 3d printing process. 9. the aacmm assembly the process of assembling the various parts of the aacmm was undertaken as soon as the fabrication and 3d printing processes were finished. the process required the same progress of assembling the parts as the design and fabrication processes. starting with the base and the 3d printed base legs, moving to the rotating base, and then the central arm fixture. once the fixture was installed, the main arm was attached, followed by the probe arm. during the assembly, various m3 and m2 screws were used. figure (20) shows the progress of the aacmm assembly process. dhuha mohammed mahmood al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 4254 (2020) 52 fig. 20. assembly parts. 10. results and conclusion in this exploration, a beneficial model of the aacmm was proposed implemented, to show the machine and to demonstrate the structure idea. the aacmm model was utilized to approve the arrangement of the kinematic model. results demonstrate that the kinematic position model is proficient in deciding the position when contrasted and estimations are taken physically. a common distinction of under 0.5 mm more than 30 points was accomplished. this consequence of the aacmm estimations falls inside the blunder spending plan. the device was tested on a freeform surface part (mouse) as shown in figure (21). fig. 21. during the examination of the aacmm device. dhuha mohammed mahmood al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 4254 (2020) 53 11. references [1] k. gromczak et al., "validation model for coordinate measuring methods based on the concept of statistical consistency control," precision engineering, vol. 45, pp. 414-422, 2016/07/01/ 2016. [2] l. nawara, m. kowalski, and j. sladek, "the influence of kinematic errors on the profile shapes by means of cmm," cirp annals, vol. 38, no. 1, pp. 511-516, 1989/01/01/ 1989. [3] a. weckenmann, "koordinatenmesstechnik," in koordinatenmesstechnik, w. albert, ed.: carl hanser verlag gmbh & co. kg, 2011, pp. i-xviii. [4] k. c. fan, f. cheng, w. t. pan, and r. li, "analysis of the contact probe mechanism for micro-coordinate measuring machines," optoelectronics, instrumentation and data processing, vol. 46, no. 4, pp. 340-346, 2010/08/01 2010. [5] p. gąska, m. gruza, a. gąska, w. harmatys, and j. sładek, "assessment of the impact of probe head hysteresis on the accuracy of fiveaxis coordinate measuring systems," advances in science and technology research journal, vol. 11, pp. 277-282, 09/03 2017. [6] w. k. hamdan, and m. m. abdulrazaq, "sculptured surface design and implementatio by lofting design method using cross-sectional b-spline curves". al-khwarizmi engineering journal, 14(2), pp.92-82,2018. )2020( 4254، صفحة 1العدد ، 16دجلة الخوارزمي الهندسية المجلم ضحى محمد محمود 54 تحسين عمليات الهندسة العكسية باستخدام آلة قياس إحداثيات الذراع المفصلية ** أحمد زيدان الشمري *ضحى محمد محمود *،** قسم هندسة التصنيع المؤتمت/ كلية الهندسة الخوارزمي/ جامعة بغداد gmil.com55duhamohammed@ :األلكترونيالبريد * ahmadhzaam@yahoo.comالبريد األلكتروني: ** الخالصة فكرة البحث هو في الهندسة العكسية من خالل تصميم وتصنيع جهاز ،من خالله يتم الحصول على المخططات التصميمية ألي جزء ميكانيكي عن ميا وبهذا لهذا المنتج المعين ومن ثم نقل تلك المعلومات الى احدى المكائن المبرمجة رق ( sti ) طريق تصويره فتكون له بيانات رقميه مجسمه على صيغة في هذه الرسالة ، تم اقتراح نموذج وتم تصنيعه واستخدامه في الهندسة العكسية ،تمت محاولة تكون العملية سهله لتصنيع األجزاء الغير معروفة المخططات. المعقدة ، والتغلب مثل حل حركيات الحركة aacmm الجديد معالجة المشكالت الشائعة لـ aacm جديد وصنعه. حاول تصميم aacmmتصميم جديد ومتوافق يدمج جميع عوامل التصميم المرنة. aacmm على حدود مساحة العمل ، وتجنب التفرد والتخلص من آثار خطأ التصميم من خالل تصميم ية المطاف دقة. يُقال إن وفي نها aacmm يتم إعطاء أنواع مختلفة من عوامل التصميم والقيود التي تؤثر بشكل كبير على عمليات اإلنتاج والتصنيع دقيقة. تم التحقق من عوامل التكلفة والوقت في التصميم والتصنيع لها التأثير األكثر أهمية. ومع ذلك ، يجب مراعاة عوامل الدقة وبيئة العمل إلجراء قياسات من أن التصميم كان صحيًحا من الناحية الهيكلية.حيث يتم صحة التصميم من خالل أساليب مختلفة ، مثل استخدام تقنيات قياس العناصر المحدودة ، للتأكد ديل على النتائج الحصول من خالله على ما يسمى بالغيمة النقطية في علم المجسمات ثالثية االبعاد . تم اجراء الحسابات والقياسات باستخدامه وتم التتع ن االنحرافات والتفاوتات باألبعاد . وتم بالفعل الحصول على جهاز فعال وعملي حقيقي لبيا لألجزاء األصلية والتقليدية ( geomagic x ) باستخدام برنامج ة بالجهاز باستخدام يتضمن الهدف الرئيسي من هذه الورقة البحثية تصميم وتنفيذ نموذج ألة تنسيق االحداثيات المفصلية الذراع .يتم التحكم والبرمجة الخاص . يقوم المتحكم باستالم حاالت المتحسسات الموزعة بجميع الفاصل للروبوت وينفذ القرارات نسبة arduinoم مع المتحك processing 3برنامج للبرنامج لتشغيل المشغالت. يمكن استخدام هذا النموذج في المختبرات الهندسية العلمية لتقريب الجانت النظري على الجانب العملي. 17 دراست انخظائض انًٍكانٍكٍـت نًـادة يركبت راث أساش بىنًٍري يمىاة (al2o3) أو (al)بذلائك ين انذكتىر ػهً حسٍن ػتٍىي انذكتىر جىاد كاظى ػهٍىي سؼذ يٍخائٍم إٌهٍا لغُ ٕ٘ذعخ اٌّــٛاد/ اٌزىٌٕٛٛع١خ اٌغبِؼخ (received 4 april 2007; accepted 21 august 2007) يهخض انبحث رُ رؾؼ١ش ِبدح ِشوجخ ث١ٌّٛش٠خ ِىٛٔخ ِٓ سارٕظ اٌجٌٟٛ اعزـش غ١ـش اٌّشجــغ اٌّمٜٛ ثذلبئك ِٓ أٚوغ١ـذ األ١ٌّٕـَٛ (al2o3) َٛأٚ دلبئــك ِؼذ١ٔخ ِـٓ األ١ٌّٕ (al)ٚثؾغُ دلبئك (30 µm) (%5 ,%10 ,%15 ,%20) ٚثىغـٛس ٚصٔـ١ٗ ثٕغت . 1500) ٚثٍغذ (al) ػٕذ اٌزم٠ٛخ ثذلبئك (.mpa 2400) أظٙشد ٔزبئظ اخزجبس اٌشذ ثؤْ أػٍٝ ل١ّخ ٌّؼبًِ اٌّشٚٔخ ثٍغذ mpa.) ػٕذ اٌزم٠ٛخ ثذلبئك (al2o3) ٟٔ(% 20) ػٕذ وغش ٚص . ٚألظٝ أعٙبد (f.s)أِب ػٕذ أعشاء اخزجبساد ِمبِٚخ االٔؾٕبء ٚاٌظذِخ فؤظٙشد إٌزبئظ ثؤْ وً ِٓ ِمبِٚخ االٔؾٕبء ؽ١ش وبٔذ ٔزبئظ اٌؼ١ٕبد اٌّمٛاح . رضداد ِغ ص٠بدح ٔغجخ اٌىغش اٌٛصٟٔ(kc) ِٚزبٔخ اٌىغش (gc) ِٚمبِٚخ اٌظذِخ max) )τ اٌمض %45.45, %25, %41)ثٕغجخ (% 20) ػٕذ وغـش ٚصٟٔ (al2o3) أػٍٝ ِٓ ٔزبئـظ اٌؼ١ٕبد اٌّمٛاح ثذلبئك (al)ثذلبئك ثٕغجخ (al) وبٔذ أػٍٝ ِٓ طالدح اٌؼ١ٕبد اٌّمٛاح ثذلبئك (al2o3)ث١ّٕب طالدح اٌؼ١ٕبد اٌّمٛاح ثذلبئك. ػٍٝ اٌزٛاٌٟ(45.43%, . (% 20) ػٕذ وغش ٚصٟٔ (% 2.82) :انًمذيت أوضش رزىْٛ اٌّبدح اٌّشوجخ ػٓ ؽش٠ك رشو١ت ِبدر١ٓ أٚ ٌزى٠ٛٓ ِبدح عذ٠ذح رّزبص ثظفبد أفؼً ٚرخزٍف ػٓ [.1]ِىٛٔبرٙب األط١ٍخ ٚرؼذ اٌّٛاد اٌّشوجخ راد األعبط اٌج١ٌّٛشٞ ِٓ أْ اٌزم٠ٛخ ثبٌذلبئك رؾذس ػٕذِب [. 2،3]ألذَ اٌّٛاد اٌّشوجخ رؼًّ اٌؾج١جبد وؼٛائك ٌزش٠ٛٗ اٌّبدح األعبط ثغجت طالدرٙب اٌؼب١ٌخ ٚػذَ رش٠ٛٙٙب إصٕبء اٌزؾ١ًّ ٚرىْٛ ػٍٝ ػذح أٔٛاع ٚأشىبي ِٕٙب اٌىش٠ٚخ ٚاٌمشش٠خ ٚاألثش٠خ ٚاٌخ١ط١خ ؽ١ش رؼًّ اٌذلبئك ػٍٝ ص٠ــبدح اٌغغـبءح (rigidity) ًِٚص٠ـبدح ِمبِٚـخ اٌظذِـخ ٚرؾغ١ٓ ِؼب [.4]اٌزّذد اٌؾشاسٞ ٌٍّبدح األعبط ٚعّبػزٗ ثذساعخ nicolais لبَ اٌجبؽش 1981 فٟ ػبَ رؤص١ش اٌىغش اٌؾغّٟ ػٍٝ ِمبِٚخ اٌشذ ِٚؼبًِ اٌّشٚٔخ ٚرٌه ػٓ ؽش٠ك إعشاء اخزجبس اٌشذ ػٍٝ ِبدح ِشوجخ ِىٛٔخ ِٓ اٌجٌٟٛ عزب٠ش٠ٓ اٌّمٜٛ ثذلبئك ِٓ اٌضعبط ، ٚلذ أظٙشد إٌزبئظ ص٠بدح ثم١ّخ ِؼبًِ اٌّشٚٔخ ٚٔمظبْ فٟ ِمبِٚخ اٌشذ ِغ ص٠بدح اٌىغش اٌمبئك ،أْ اٌذساعخ ٘زٖ أٍّ٘ذ رؤص١ش وً ِٓ [.5]ؽغُ ٚشىً اٌذلبئك (fracture toughness) أِـب ف١ّـب ٠زؼـٍك ثّزبٔخ اٌىغش (kc) ٌٍّبدح اٌّشوجخ اٌذلبئم١خ ٚو١ف١خ رؤص١ش٘ب ثٕٛع اٌذلبئك اٌّؼبفخ ٚؽغّٙب ٚؽج١ؼخ اٌشثؾ ث١ٓ األؽٛاس فمذ رّذ ,lipatay ِؼبٌغزٙب ِٓ لجً ِغّٛػخ ِٓ ثبؽض١ٓ ُِٕٙ maik & krysztafkiewicz لبِٛا ثذساعخ اٌزم٠ٛخ ؽ١ش ثبٌذلبئك ، ٚاعزٕزغٛا ثبْ رفبػً اٌذلبئك ِغ اٌّبدح اٌٍذائ١ٕخ ثؤٞ شىً ٠ؤدٞ إٌٝ اٌؾظٛي ػٍٝ ٔزبئظ أفؼً، ٚطٕفذ اٌذلبئك ػٍٝ ٘زا األعبط إٌٝ دلبئك خبٍِخ ٚدلبئك فؼبٌخ، alkhwarizmi engineering journal vol.3 , no.3 , pp 17-25 (2007) journal engineering journal alkhwarizmi engineering journal ( 2007 )26-17 انظفحت 3. انؼذد 3.يجهت انخىارزيً انهنذسٍت، انًجهذ /ػهً حسٍن ػتٍىي . د 18 a u g c c  egcc  22 3 . bd pl sf  ٚػٓ ؽش٠ك ِؼبٌغخ اٌذلبئك اٌخبٍِخ ثبٌّبدح اٌشاثطخ رظجؼ [. 6]أوضش فبػ١ٍخ ٚعّبػزٗ moloney ا٘زُ اٌجبؽش 1983 فٟ ػبَ (kc) ِٚزبٔخ اٌىغش (gc)ثؾغبة ِمبِٚخ اٌظذِخ ٌال٠جٛوغٟ اٌّؾزٛٞ ػٍٝ دلبئك صعبع١خ ٚرٛطٍٛا إٌٝ أْ ِزبٔخ اٌىغش رمً ثزؾغ١ٓ اٌشثؾ ث١ٓ األؽٛاس سغُ ص٠بدح ٚثض٠بدح اٌىغش اٌؾغّٟ رؾظً ص٠بدح ثم١ّخ . ِمبِٚخ اٌشذ [. 7]ِزبٔخ اٌىغش ٚعّبػزـٗ amdouni دسط اٌجبؽش 1990 فٟ ػبَ ِبدح ِشوجخ ِىٛٔخ ِٓ اال٠جٛوغٟ اٌّغٍؼ ثبٌىش٠بد اٌضعبع١خ ٚلذ اعزٕزظ ٘ؤالء ثؤْ (%20)ٚثٕغجخ وغش ؽغّٟ ِمذاسٖ ٕ٘بن ػذح ؽشائك ٌزؾغ١ٓ ِزبٔخ اٌىغش أِب ثبعزخذاَ ِبدح ساثطخ ث١ٓ اٌؾشٛاد ٚاٌّبدح األعبط ٌض٠بدح االٌزظبق أٚ ثئػبفخ ؽٛس ِطبؽٟ إٌٝ اال٠جٛوغٟ ٌٍؾظٛي [. 8 ](elastomeric)ػٍٝ ؽٛس ِطبؽٟ ِشْ اٌخظبئض kereem دسط اٌجبؽش 2002 ٚفٟ ػبَ ا١ٌّىب١ٔى١خ ٌال٠جٛوغٟ اٌّذػُ ثذلبئك ِٓ ا١ٌٕىً ٚلذ اعزخذَ دلبئك ثؤؽغبَ ِخزٍفخ ِغ وغش ؽغّٟ ِزغ١ش ٚلذ ٚعذ ثبٔٗ ل١ُ ِؼبًِ اٌّشٚٔخ ِٚمبِٚخ اٌخؼٛع رضداد ِغ ص٠بدح اٌىغش اٌؾغّٟ ٌٍذلبئك ٚوزٌه ص٠بدح ؽغُ اٌذلبئك لذ ؽغٓ ِٓ [. 9 ](32µm)اٌخٛاص ٌٚغب٠خ رُ دساعخ رؤص١ش ؽغُ اٌذلبئك ٚاٌىغش 2004 ٚفٟ ػبَ اٌؾغّٟ ػٍٝ ِزبٔخ اٌىغش ٌشارٕظ اال٠جٛوغٟ اٌّذػُ ثذلبئك اال١ٌِٕٛب اٌىش٠ٚخ ٚثؾغَٛ دلبئم١خ ِخزٍفخ فمذ لبَ اٌجبؽش marur ٚفش٠مٗ ثؾغبة ِزبٔخ اٌىغش فٛعذ أْ ٌؾغُ اٌذلبئك فٟ ِزبٔخ اٌىغش فٛعذ ػٕذ ؽغُ دلبئمٟ ِمذاسٖ " ِّٙب" رؤص١شا (5µm) ّٟرضداد ِزبٔخ اٌىغش ِغ اٌض٠بدح فٟ اٌىغش اٌؾغ [. 10]ٌٍذلبئك : انجسء اننظري ظٙشد اٌّٛاد اٌّشوجخ وٕز١غخ إٌٝ اٌزطٛس اٌظٕبػٟ ٚاٌزمٕٟ ٌٚزٍج١خ اٌؾبعخ اٌّزضا٠ذح إٌٝ ِٛاد عذ٠ذح راد ِٛاطفبد خبطخ رذخً وجذ٠ً ٌٍّٛاد إٌٙذع١خ األخشٜ، ٚثزٌه اؽزٍذ اٌّـٛاد اٌّشوجخ ػٍٝ اخزالف أٔٛاػٙب ِىبٔخ أْ اخز١بس .ِزمذِخ فٟ اٌزطج١مبد اٌظٕبػ١خ ِٕز أٚي ظٙٛس ٌٙب اٌّٛاد غبٌجب ِب ٠ىْٛ ػٍٝ أعبط ِب رزّزغ ثٗ اٌّبدح ِٓ . خٛاص ١ِىب١ٔى١خ ٌٚغشع أعشاء ِمبسٔخ ث١ٓ اٌخٛاص ا١ٌّىب١ٔى١خ ث١ٌّٛش٠خ ِمٛاح ثذلبئك ِؼذ١ٔخ ٚع١شا١ِى١خ ٚاٌؾشاس٠خ ٌّبدح فمذ رُ اعزخذاَ ػذح اخزجبساد ٟٚ٘ اخزجبس اٌشذ ٌغشع modulus of) (e)اٌؾظٛي ػٍٝ ِؼبًِ اٌّشٚٔخ elasticity) ِٚمبِٚخ اٌشذ (tensile strength) ٌٍّبدح اٌّشوجخ ، ٚاخزجـبس اٌظذِـخ ٌغـشع اٌؾظـٛي ػٍـٝ ِٚزبٔـخ (impact strength) (gc)ِمبِٚـخ اٌظذِـخ ِٓ (fracture toughness) (kc) اٌىغــــش [: 12,11]ػٍٝ اٌزٛاٌٟ (2)ٚ (1)اٌّؼبدالد ……………….(1) (…….(2 ............... : أْ ؽ١ش uc : (اٌطبلخ اٌّّزظخ)ؽبلخ اٌظذِخ (j) .a : m)ِغبؽخ اٌّمطغ اٌؼشػٟ 2 ) . e : (ِؼبًِ ٠ٛٔه)ِؼبًِ اٌّشٚٔخ (mpa.). ٚلـذ اعزخــذَ اخزجبس االٔؾٕبء ٌغـشع اٌؾظـــٛي ػٍٝ ِٓ اٌؼاللخ (flexural strength) (f.s)ِمبِٚخ االٔؾٕـبء ( 4)ِٓ اٌؼاللخ (max) τ ٚألظٝ أعـٙبد لض،[13( ]3) أِب اخزجبس اٌظالدح فمذ رُ ثبعزخذاَ ؽش٠مخ [14] [: 15 ( ]dشٛس ) (3 .............) …………(4) bd p 4 3 max  ( 2007 )26-17 انظفحت 3. انؼذد 3.يجهت انخىارزيً انهنذسٍت، انًجهذ /ػهً حسٍن ػتٍىي . د 19 : ؽ١ش أْ p : اٌؾًّ اٌّغٍؾ(n) ، l : ؽٛي اٌؼ١ٕخ(m) b : (m)عّه اٌؼ١ٕخ : d ، (m)ػشع اٌؼ١ٕخ : انجسء انؼًهً أْ اٌّٛاد اٌّغزخذِخ فٟ رظ١ٕغ ػ١ٕبد اٌجؾش ِىٛٔخ (اٌجٌٟٛ أعزش غ١ش اٌّشجغ)ِٓ ِبدح األعبط اٌج١ٌّٛش٠خ ٚدلبئـك ِٓ ِـبدح (al)اٌّمٜٛ ثذلبئك ِٓ ِـبدح ِؼـذ١ٔـخ . al2o3) (ع١شا١ِى١ـخ أْ سارٕظ اٌجٌٟٛ أعزش غ١ش اٌّشجغ ٠ّزبص ثخٛاص ١ِىب١ٔى١خ ع١ذح ٚاعزمشاس٠خ أثؼبد، ٚلبث١ٍخ رشاثؾ ع١ذح ِغ ِٛاد أخشٜ ِخزٍفخ ، ٚػبص١ٌٗ وٙشثبئ١خ ٚؽشاس٠خ ع١ذح، ٚعٛدح عطؼ ثؼذ اٌزظٍت، أِب األ١ٌَّٕٛ فبٔٗ ٠ّزبص ثبٌّط١ٍ١خ اٌؼب١ٌخ ٚاٌّٛط١ٍخ اٌؾشاس٠خ ٚاٌىٙشثبئ١خ اٌؼب١ٌز١ٓ أِب أٚوغ١ذ األ١ٌَّٕٛ فٙٛ ٠ّزبص ثىٛٔٗ طٍذ ٚ٘ش ٚرٚ رٛط١ٍ١خ ؽشاس٠خ ٠ج١ٓ ثؼغ خٛاص (1)الً ثىض١ش ِٓ األ١ٌَّٕٛ ٚاٌغذٚي [.16,4]اٌّٛاد اٌّغزخذِخ ٌىضح خىاص انًىاد انًستخذيت فً انبحث (1)جذول [16,4.] يؼايم انًرونت (gpa.) يماويت انشذ (mpa.) انتىطٍهٍت انحرارٌت (w/m. o c) انكثافت (kg/m 3 ) انًادة 2.06– 4.41 70.3 103 0.17 1200 انبىنً أستر غٍر انًشبغ 71 60 247 2700 يسحىق األنًنٍىو 304 282 551 39 3720 يسحىق أوكسٍذ األنًنٍىو ، 10، %5%)رُ رظ١ٕغ ِٛاد ِشوجخ ثٕغجخ وغش ٚصٟٔ ٌىً ِٓ ِٛاد اٌزم٠ٛخ ٚرٌه ثبالػزّبد ػٍٝ (20، %15% .[17]( 6)ٚ (5)اٌؼاللبد …..(5 ) %100 c p p w w w …..(6 ) : ؽ١ش أْ wm , wp : اٌىغش اٌٛصٟٔ ٌّبدح اٌزم٠ٛخ ِٚبدح األعبط . ػٍٝ اٌزٛاٌٟ wc , wm , wp : ٚصْ وً ِٓ ِبدح اٌزم٠ٛخ ِٚبدح األعبط . ٚاٌّبدح اٌّشوجخ ػٍٝ اٌزٛاٌٟ رُ أعشاء ػذح اخزجبساد ػٍٝ اٌّبد اٌّظٕؼخ ٚاٌغذٚي ٠ٛػؼ االخزجبساد اٌزٟ اعزخذِذ فٟ اٌجؾش ٚؽغت (2) :ِٛاطفبد وً ٔظبَ ٌىضح االختباراث انًستخذيت ونىع انًىاطفاث (2)جذول .وانجهاز انًستخذو نكم اختبار نىع انًىاطفاث اسى االختبار ث انجهاز انًستخذو اختبار انشذ 1 حسب انًىاطفاث األيرٌكـٍت (astm d – 638) instron 1195 tensile test اختبار انظذيت 2 حسب اننظاو انؼانًً (iso 179) charpy impact test 3 اختبار يماويت االنحناء حسب انًىاطفاث األيرٌكـٍت (astm d – 790) three point bending test اختبار انظالدة -4 حسب انًىاطفاث األيرٌكـٍت (astm d – 2240) shore d test 0 0100 c m m w w w ( 2007 )26-17 انظفحت 3. انؼذد 3.يجهت انخىارزيً انهنذسٍت، انًجهذ /ػهً حسٍن ػتٍىي . د 20 : اننتائج وانًنالشت : (tensile test)اختبار انشذ 1 اٌؼاللخ ث١ٓ ِمبِٚخ اٌشذ (2)ٚ (1) ٠ٛػؼ اٌشى١ٍٓ ٌّبدح ِشوجخ ِٓ اٌجٌٟٛ أعزش اٌّمٛاح ٚصِٟٔغ اٌىغش اي . ػٍٝ اٌزٛاٌٟ( al2o3 ) ٚدلبئـك ِٓ ( al )ثذلبئك ِٓ ٠جذٚ ثؤْ ِمبِٚخ اٌشذ ٌٍّبدح (1) فّٓ خالي اٌشىً اٌّشوجخ اٌّمٛاح ثذلبئك ِٓ األ١ٌَّٕٛ رضداد ثؼاللخ الخط١خ ِغ ٠ٚؼضٜ ٘زا إٌٝ لٛح اٌشثؾ اٌؼب١ٌخ ث١ٓ ٚصٟٔص٠بدح اٌىغش اي ِبدح األعبط ِٚبدح اٌزم٠ٛخ ٚاٌزٞ ٠ؤدٞ إٌٝ رم١ًٍ االٔضالق . أصٕبء اٌشذ إػبفخ إٌٝ اٌّط١ٍ١خ اٌؼب١ٌخ ٌّبدح األ١ٌَّٕٛ 31) أْ ل١ّخ ِمبِٚخ اٌشذ ٌٍج١ٌّٛش غ١ش اٌّمٜٛ ٟ٘ mpa.) َٛٚلذ رؾغٕذ ِمبِٚخ اٌشذ ػٕذ إػبفخ دلبئك األ١ٌّٕ ، ٘زا (% 20) ٚصٟٔ ػٕذ وغش (.mpa 48)ؽ١ش ثٍغذ ٠ؼٕٟ ثؤْ اٌّبدح اٌّشوجخ لذ رؾغٕذ ثٕغجخ (54.84 %) . فؤٔٗ ٔالؽع ثؤْ ِمبِٚخ اٌشذ (2) أِب ِٓ خالي اٌشىً ٌٍّبدح اٌّشوجخ اٌّمٛاح ثذلبئك ِٓ أٚوغ١ذ األ١ٌَّٕٛ رمً ثؼاللخ ٠ٚؼٛد اٌغجت إٌٝ أْ اٌشثؾ ٚصٟٔالخط١خ ِغ ص٠بدح اٌىغش اي اٌؼؼ١ف ٠ؤدٞ إٌٝ االؽزىبن ث١ٓ ِبدح اٌزم٠ٛخ ِٚبدح األعبط ، ثبإلػبفخ إٌٝ أْ [18]ٚاٌزٟ رغجت االٔضالق ث١ٓ اٌذلبئك ِبدح أٚوغ١ذ األ١ٌَّٕٛ ِبدح ع١شا١ِى١خ ٘شخ راد ِط١ٍ١ٗ ل١ٍٍخ ِّب أدد إٌٝ رم١ًٍ ِمبِٚخ اٌشذ ِمبسٔخ ِغ اٌّبدح اٌّشوجخ ِٚٓ اٌشىً ٔـالؽع ثؤْ ِمبِٚخ . اٌّمٛاح ثذلبئك ِٓ األ١ٌَّٕٛ فٟ ؽبٌخ اٌجٌٟٛ اعزش (.mpa 31)اٌشذ لذ أخفؼذ ِٓ ػٕذ إػــبفخ دلبئك أٚوغ١ذ األ١ٌَّٕٛ (.mpa 18)ٌٛؽذٖ إٌٝ ،أٞ ثٕغـخ رخف١غ ِمذاس٘ب (%20) ٚصٟٔثىغش (41.9 %) . ٠ٛػؼ ِمبسٔخ ث١ٓ ِؼبًِ اٌّشٚٔخ ٌٍّبدح (3) أِب اٌشىً ٌّبدح اٌزم٠ٛخ ٌىال إٌٛػ١ٓ ِٓ ٚصٟٔاٌّشوجخ ِغ اٌىغش اي اٌزم٠ٛخ األ١ٌَّٕٛ ٚأٚوغ١ذ األ١ٌَّٕٛ ِٚٓ خالي اٌشىً ٠جذٚ ثؤْ ِؼبًِ اٌّشٚٔخ ٠ضداد ثؼاللبد الخط١خ ِغ ص٠بدح اٌىغش ٌّبدرٟ اٌزم٠ٛخ األ١ٌَّٕٛ ٚأٚوغ١ذ األ١ٌَّٕٛ ٠ٚؼٛد ٚصٟٔاي ٠ؤدٞ إٌٝ رم١ًٍ ؽشوخ ٚصٟٔرٌه إٌٝ أْ ص٠بدح اٌىغش اي [. 18]اٌغض٠ئبد ٚثبٌزبٌٟ رؤدٞ إٌٝ رم١ًٍ االٔفؼبي أْ أػٍٝ ل١ّخ ٌّؼبًِ اٌّشٚٔخ رُ اٌؾظٛي ػ١ٍٗ ٟ٘ ػٕذ ؽ١ش ثٍغ ِؼبًِ اٌّشٚٔخ ٌٍّبدح (% 20)وغش ٚصٟٔ (.mpa 1500)اٌّشوجخ اٌّمٛاح ثذلبئك أٚوغ١ذ األ١ٌَّٕٛ ِٚؼبًِ اٌّشٚٔخ أٞ (.mpa 2400)ٌٍّبدح اٌّشوجخ اٌّمـٛاح ثذلبئــك األ١ٌَّٕٛ . (% 60) ثٕغجـخ ص٠بدح ِمذاس٘ــب : اختبار انظذيت2 ٌٍذلبئك ٚص٠ٟٔٛػؼ رؤص١ش رغ١ش اٌىغش اي (4) أْ اٌشىً ٚٔالؽع (gc)اٌّؼبفخ إٌٝ اٌجٌٟٛ أعزش ػٍٝ ِمبِٚخ اٌظذِخ ٚصِٟٔٓ اٌّخطؾ أْ ِمبِٚخ اٌظذِخ رضداد ثض٠بدح اٌىغش اي ٌىً ِٓ دلبئك األ١ٌَّٕٛ ٚدلبئك أٚوغ١ذ األ١ٌَّٕٛ ثؼاللبد الخط١خ ٚرٌه ٔز١غخ ػًّ ٘زٖ اٌذلبئك وؾبعض أِبَ اٌشك إٌبِٟ خالي اٌّبدح اٌّشوجخ أٞ رؼًّ ػٍٝ إػبلخ ّٔٛ اٌشك ٚ٘زا ع١ؤدٞ إٌٝ رغ١ش اٌشك ِٓ شىٍٗ ٚارغب٘ٗ ِّب ٠ؤدٞ إٌٝ رؾٌٛٗ إٌٝ ِغّٛػخ شمٛق صب٠ٛٔخ ، أْ ٘زا اٌزغ١ش فٟ شىً اٌشك ٚارغب٘ٗ أدد إٌٝ ص٠بدح اٌّغبؽخ اٌغطؾ١خ ٌٍىغش ٚاٌطبلخ اٌّظشٚفخ ٚ٘زٖ اٌؼٛاًِ أدد إٌٝ ص٠بدح ِمبِٚخ اٌّبدح ٚ٘زٖ اٌؾبٌخ رؾظً ثشىً أفؼً ػٕذِب ٠ىْٛ ٕ٘بن سثؾ لٛٞ ث١ٓ اٌّبدح األعبط . ٚاٌذلبئك وّب ٘ٛ اٌؾبي فٟ دلبئك األ١ٌَّٕٛ ٚاٌّبدح األعبط أِب فٟ ؽبٌخ اٌشثؾ األلً لٛح فؤْ اٌزم٠ٛخ رزُ ثآ١ٌخ ِخزٍفخ رؼزّذ ػٍٝ ِاللبح اٌشك ٌٍغطٛػ اٌج١ٕ١خ اٌؼؼ١فخ ٚػ١بع ، ٚأْ ِمبِٚخ اٌظذِخ [19]أٚرؾشس عضء ِٓ ؽبلزٗ ػٕذ٘ب ٌٍذلبئك اٌّؼبفخ ، ٚصٌٍّٟٔبدح رزؤصش ثٕٛع اٌذلبئك ٚاٌىغش اي ؽ١ش اِزٍىذ اٌؼ١ٕبد اٌّمٛاح ثذلبئك األ١ٌَّٕٛ أػٍٝ ِمبِٚخ 12.5) ؽ١ش ثٍغذ (% 20) ٚصٟٔطذِخ ػٕذ وغش kj/m 2 ث١ّٕب وبٔذ أػٍٝ ِمبِٚخ طذِخ ٌٍؼ١ٕبد اٌّمٛاح ( ٚصٟٔثذلبئك أٚوغ١ذ األ١ٌَّٕٛ اٌّؼبفـــخ ػٕذ ٔفظ اٌىغــش اي ٟ٘ (10kj/m 2 ِٚٓ األعجبة . (4) ٚوّب ِج١ٓ فٟ اٌشىـً ( األخشٜ اٌزٟ أدد إٌٝ ص٠بدح ِمبِٚخ اٌظذِخ ٟ٘ اٌّط١ٍ١خ اٌؼب١ٌخ ٌأل١ٌَّٕٛ ِمبسٔخ ثّط١ٍ١ٗ أٚوغ١ذ األ١ٌَّٕٛ ؽ١ش أْ اٌّبدح اٌّط١ٍ١خ رؾزبط إٌٝ ؽبلخ وغش أػٍٝ ِٓ اٌطبلخ . اٌّظشٚفخ ٌىغش اٌّبدح اٌٙشخ ( 2007 )26-17 انظفحت 3. انؼذد 3.يجهت انخىارزيً انهنذسٍت، انًجهذ /ػهً حسٍن ػتٍىي . د 21 ٚصٟٔ فؤٔٙب رضداد ِغ ص٠بدح اٌىغش اي(kc) أِب ِزبٔخ اٌىغش ٌٍذلبئك اٌّؼبفخ ٚوّب ٘ٛ ٚاػؼ ، ٠ٚؼٛد عجت ص٠بدح ِزبٔخ اٌىغش ِغ ص٠بدح (5) فٟ اٌشىً اٌىغش اٌٛصٟٔ إٌٝ ص٠بدح ِؼبًِ اٌّشٚٔخ ٌٍّبدح اٌّشوجخ ِغ ص٠بدح اٌىغش اٌٛصٟٔ وّب اْ ثض٠بدح اٌىغش اٌٛصٟٔ ٠ؤدٞ إٌٝ . (أٞ ص٠بدح اٌطبلخ اٌّّزظخ)ص٠بدح ِزبٔخ اٌّبدح اٌّشوجخ ٚصٟٔ أْ أػٍٝ ِزبٔخ وغش رُ اٌؾظٛي ػ١ٍٙب ػٕذ وغش mpa.m 5.5) ؽ١ش ثٍغذ (20%) 0.5 ٌٍّبدح اٌّشوجخ ( 3.9) اٌّمــٛاح ثذلبئـك األ١ٌَّٕٛ ث١ّٕــب ثٍغذ mpa.m 0.5 ٌٍّبدح اٌّشوجخ اٌّمٛاح ثذلبئك اٚوغ١ذ األ١ٌَّٕٛ ( . (%41)أٞ ثٕغجخ رؾغٓ ِمذاس٘ب : اختبار يماويت االنحناء3 ٌٍذلبئك ٚصٟٔرؤص١ش اٌىغش اي (6) اٌشىً ٠ٛػؼ اٌّؼبفخ ػٍٝ ِمبِٚخ االٔؾٕبء ٚلذ أػطذ اٌّبدح اٌّشوجخ ِمبِٚخ أؾٕبء أػٍٝ ِٓ اٌّبدح األ١ٌَّٕٛ اٌّمٛاح ثذلبئك األ١ٌَّٕٛ، ٠ٚؼٛد اٌغجت إٌٝ اٌّشوجخ اٌّمٛاح ثذلبئك أٚوغ١ذ لٛح اٌزشاثؾ ث١ٓ اٌجٌٟٛ أعزش غ١ش اٌّشجغ رىْٛ ػب١ٌخ ِغ دلبئك األ١ٌَّٕٛ ٚرىْٛ ٘زٖ اٌمٛح الً ِغ دلبئك أٚوغ١ذ ػٕـذ وغـش ٚصٔـٟ أػٍٝ ل١ّخ ٌّمبِٚخ وبٔذ األ١ٌَّٕٛ، أْ ٌٍّبدح اٌّشوجخ (.mpa 765) ؽ١ش ثٍغــــذ (% 20) اٌّمـٛاح ثذلبئك األ١ٌَّٕٛ ث١ّٕب ػٕذ إػبفخ دلبئك أٚوغ١ذ ثٍغذ ِمبِٚخ االٔؾٕبء ٚصٟٔٚػٕذ ٔفظ اٌىغش اياأل١ٌَّٕٛ (526 mpa.). أْ لٛح اٌزشاثؾ ث١ٓ اٌّبدح األعبط ِٚبدح اٌزم٠ٛخ وبْ ٌٙب ا٠ؼبً اصش ثبٌغ فٟ أػطبء اٌؼ١ٕبد ألظٝ أعٙبد ٚاٌزٟ أدد إٌٝ اِزالن (maximum shear stress)لض األ١ٌَّٕٛ أػٍٝ ِٓ ػ١ٕبد ػ١ٕبد اٌجٌٟٛ اعزش اٌّمٛاح ثذلبئك اٌجٌٟٛ اعزش اٌّمٛاح ثذلبئك اٌجٌٟٛ اعزش ٌٛؽذٖ ٚػ١ٕبد اٌّمٛاح فمذ اِزٍىذ ػ١ٕبد اٌّبدح اٌّشوجخ . أٚوغ١ذ األ١ٌَّٕٛ (.mpa 9.6)األ١ٌَّٕٛ ألظٝ أعٙبد لض ِمذاس٘ب ثذلبئك ػ١ٕبد اٌّبدح اٌّشوجخ أِب(% 20)ػٕذ وغش ٚصٟٔ األ١ٌَّٕٛ فؤلظٝ أعٙبد لض وبْ ػٕذ اٌّمٛاح ثذلبئك أٚوغ١ذ أٞ أْ ثؤػبفخ دلبئك (.6.6mpa)ٚصٟٔ ٚ٘ٛائفظ اٌىغش ػٕذ وغــش (%45.45)األ١ٌَّٕٛ ؽظٍٕب ػٍٝ ٔغجخ رؾغٓ أرا ِب لٛسٔذ ِغ اٌّبدح اٌّشوجخ اٌزٟ رُ (%20) ٚصٟٔ رم٠ٛزٙب ثذلبئك أٚوغ١ذ األ١ٌَّٕٛ ػٕذ ٔفظ اٌىغش اٌٛصٟٔ ،وّب ػٍٝ ٚصٟٔاٌزٞ ٠ج١ٓ رؤص١ش اٌىغش اي (7)ِج١ٓ فٟ اٌشىً . ألظٝ أعٙبد لض : اختبار انظالدة4 ثؤْ اٌظالدح ٌّبدح اٌجٌٟٛ اعزش (8) ٠زؼؼ ِٓ اٌشىً غ١ش اٌّشجغ رضداد ثئػبفخ وً ِٓ دلبئك األ١ٌَّٕٛ ٚدلبئك أٚوغ١ذ األ١ٌَّٕٛ ٚرغزّش اٌظـالدح ثبٌض٠ـبدح ِغ ص٠بدح اٌىغـش اٌّؼبفخ رؤص١ش وج١ش ػٍٝ طالدح ٚأْ ٌٕـٛع اٌذلبئكٚصٟٔاي .اٌّبدح اٌّشوجخ إٌبرغخ ٚاػزّبداً ػٍٝ طالدح اٌذلبئك اٌّؼبفخ shore 87) أْ طالدح اٌجٌٟٛ أعزش غ١ش اٌّشجغ ٌٛؽذٖ d ) ٌٚىٓ ػٕذ إػبفخ دلبئك األ١ٌَّٕٛ فؤْ اٌّبدح اٌّشوجخ ٟٚ٘ (% 20) ٚصٟٔاِزٍىذ أػٍٝ طالدح ػٕذ اٌىغش اي (88.7 shore d) ٌَٛٚىٓ ػٕذ إػبفخ دلبئك أٚوغ١ذ األ١ٌّٕ shore 91.2) فؤْ اٌّبدح اٌّشوجخ اِزٍىذ طالدح ثٍغذ d)أٞ ثٕغجخ رؾغٓ ِمذاس٘ب ٚصٔــٟػٕذ ٔفظ اٌىغش اي ، أرا ِب لٛسٔذ ِغ اٌّبدح اٌّشوجخ اٌّمٛاح ثذلبئك (% 2.82) األ١ٌَّٕٛ ، ٚ٘زٖ اٌض٠بدح فٟ طالدح اٌجٌٟٛ أعزش غ١ش اٌّشجغ اٌّمٜٛ ثذلبئك ِٓ أٚوغ١ذ األ١ٌَّٕٛ رؼٛد إٌٝ أْ ٘زٖ اٌذلبئك . ٟ٘ دلبئك ع١شا١ِى١خ ٚاٌزٟ رّزبص ثبٌظالدح اٌؼب١ٌخ ( 2007 )26-17 انظفحت 3. انؼذد 3.يجهت انخىارزيً انهنذسٍت، انًجهذ /ػهً حسٍن ػتٍىي . د 22 االستنتاجاث ف١ّب ٠ٍٟ ػشع ألُ٘ االعزٕزبعبد اٌزٟ رُ اٌزٛطً : إ١ٌٙب ؽظٛي ص٠بدح فٟ ِمبِٚخ اٌشذ ٌّبدح ِشوجخ ِٓ اٌجٌٟٛ -1 اعزش اٌّمٜٛ ثذلبئك األ١ٌَّٕٛ ِغ ص٠بدح اٌىغش اٌٛصٟٔ ٚص٠بدح ِؼبًِ اٌّشٚٔخ ثٕغجخ (% 54.84)ثٕغجخ ، ث١ّٕب رمً ِمبِٚخ (% 20)ػٕذ وغش ٚصٟٔ (60%) األ١ٌَّٕٛ اٌشذ ٌٍّبدح اٌّشوجخ اٌّمٛاح ثذلبئك أٚوغ١ذ ػٕذ ٔفظ (% 41.9)ِغ ص٠بدح اٌىغش اٌٛصٟٔ ثٕغجخ .اٌىغش اٌٛصٟٔ ٌٕٚفظ ؽغُ اٌذلبئك ػٕذ ص٠بدح اٌىغش اٌٛصٟٔ ٌٍذلبئك اٌّؼبفخ رضداد -2 ِٚزبٔخ اٌىغش(gc)ِمبِٚخ اٌظذِخ 3 (kc) ٚرىْٛ ٘زٖ اٌض٠بدح أػٍٝ فٟ ؽبٌخ اٌّبدح 12.5)اٌّشوجخ اٌّمٛاح ثذلبئك األ١ٌَّٕٛ ؽ١ش ثٍغذ kj/m 2 .(% 20) ػٕذ وغش ٚصٟٔ ( رضداد ِمبِٚخ االٔؾٕبء ٚألظٝ أعٙبد لض ِغ ص٠بدح -4 اٌىغش اٌٛصٟٔ ػٕذ ؽغُ دلبئك صبثذ ٌٍّبدح اٌّشوجخ ، ٚثٍغ (.mpa 526)ؽ١ش ثٍغذ أػٍٝ ِمبِٚخ ٌالٔؾٕبء 20) ػٕذ وغش ٚصٟٔ (.mpa 9.6) لض أعٙبدألظٝ . (al) ٌٍّبدح اٌّشوجخ اٌّمٛاح ثـ (% رضداد طالدح اٌّبدح اٌج١ٌّٛش٠خ ِغ ص٠بدح اٌىغش 5 ؽ١ش ثٍغذ أػٍٝ طالدح اٌٛصٟٔ ٌٍذلبئك اٌّؼبفخ ، (91.2 shore d) ٌٍّبدح اٌّشوجخ اٌّمٛاح ثذلبئك أٞ ثٕغجخ (% 20)ػٕذ وغش ٚصٟٔ اٚوغ١ذ األ١ٌَّٕٛ ِمبسٔخ ِغ اٌّبدح اٌّشوجخ اٌّمٛاح (% 2.82)رؾغٓ .ثذلبئك األ١ٌَّٕٛ ( 2007 )26-17 انظفحت 3. انؼذد 3.يجهت انخىارزيً انهنذسٍت، انًجهذ /ػهً حسٍن ػتٍىي . د 23 يوضح ( 3 )شكل العالقة بين معامل والكسر (e)المرونة الوزني لمادة مركبة من البولي أستر المقواة بدقائق من األلمنيوم وأوكسيد .األلمنيوم ٌىضح انؼاللت بٍن يماويت ( 4 )شكم وانكسر انىزنً نهذلائك انًضافت (gc)انظذيت .إنى انبىنً أستر 0 5 10 15 20 weight fraction (%) 1000 1200 1400 1600 1800 2000 2200 2400 m o d u lu s o f e la s ti c it y ( m p a .) al al2o3 0 5 10 15 20 weight fraction (%) 0 2 4 6 8 10 12 14 im p a c t s tr e n g th ( k j /m ^ 2 ) al al2o3 0 5 10 15 20 weight fraction (%) 100 200 300 400 500 600 700 800 f le x u ra l s tr e n g th ( m p a .) al al2o3 ٌىضح انؼاللت بٍن يماويت انشذ يغ انكسر ( 1 )شكم انىزنً نهًادة انًركبت ين انبىنً أستر انًمىاة . بذلائك ين األنًنٍىو 0 5 10 15 20 weight fraction (%) 15 20 25 30 35 40 t e n s il e s tr e n g th ( m p a .) يوضح ( 2 )شكل العالقة بين مقاومة الشد مع الكسر الوزني لممادة المركبة من البولي أستر المقواة بدقائق من .أوكسيد األلمنيوم ( e) ٌىضح انؼاللت بٍن يؼايم انًرونت ( 3 )شكم وانكسر انىزنً نهذلائك انًضافت إنى انبىنً أستر .انًمىاة بذلائك ين االنًنٍىو واوكسٍذ االنًنٍىو ٌىضح انؼاللت بٍن يماويت انشذ يغ انكسر ( 2)شكم انىزنً نهًادة انًركبت ين انبىنً أستر انًمىاة . بذلائك ين اوكسٍذ األنًنٍىو ( 2007 )26-17 انظفحت 3. انؼذد 3.يجهت انخىارزيً انهنذسٍت، انًجهذ /ػهً حسٍن ػتٍىي . د 24 وانكسر انىزنً (kc) ٌىضح انؼاللت بٍن يتانت انكسر( 5 )شكم .نهذلائك انًضافت إنى انبىنً أستر ٌىضح انؼاللت بٍن يماويت االنحناء وانكسر انىزنً ( 6 )شكم نًادة يركبت ين انبىنً أستر انًمىاة بذلائك األنًنٍىو وأوكسٍذ . األنًنٍىو ٌىضح انؼاللت بٍن انظالدة وانكسر انىزنً نًادة ( 8 )شكم يركبت ين انبىنً أستر انًمىاة بذلائك األنًنٍىو وأوكسٍذ األنًنٍىو 0 5 10 15 20 weight fraction (%) 1 2 3 4 5 6 f ra c tu re t o u g h n es s ( m p a . m ) al al2o3 0 5 10 15 20 weight fraction (%) 2 3 4 5 6 7 8 9 10 m a x . s h e a r s tr e s s ( m p a .) al al2o3 0 5 10 15 20 weight fraction (%) 86 87 88 89 90 91 92 s h o re d al2o3 al ٌىضح انؼاللت بٍن االظى اجهاد لض وانكسر ( 7 )شكم انىزنً نًادة يركبت ين انبىنً أستر انًمىاة بذلائك األنًنٍىو وأوكسٍذ األنًنٍىو ( 2007 )26-17 انظفحت 3. انؼذد 3.يجهت انخىارزيً انهنذسٍت، انًجهذ /ػهً حسٍن ػتٍىي . د 25 reference 1l. holliday "composite material", elsevier publishing, london, 1966. 2j. w. weeton, m. p. dean, l.t. karyn, '' engineering's guide to composite material'', published by american society for metals,(1987). 3n. l. hancox, " metals and material "vol.2 (1986). 4w.d.callister,jr.,"materials science and engineering an introduction" 6 th ed., john wiely and sons,inc. 2003. 5l. nicolais, g. guerra, c.migliaresi, l. niccdemo & a. dibeenedetto, "mechanical properties of glass – bead filled polystyrene composite", journal of composite, vol.12 (1981). 6m. maik & a. krysztafkiewicz,'' effect of fillers on the properties of urethane polymers'', international journal polymer science and technology, vol.8 (1981). 7a. c. moloney, h. h. kuszh & h. r. stieger, " the fracture of particulaate filled epoxiede resins ",part1 journal of materials science, vol.18 (1983). 8n. amdouni , h. sautereau , j. f. gerard , f. fernagut , g. coulon & j. m. lefebvre'' coated glass beads epoxy composites: influence of the interlayer thickness on pre–yielding & fracture properties'', journal of materials science, vol.25,(1990). 9h. a. kereem,'' study the influence of adding nickel powder to a thermosetting epoxy resin on the mechanical properties'',m. sc. thesis, university of technology,(2002). 10p. r. marur , r. c. batra, g. garcia & a. c. loos ,''static & dynamic fracture toughness of epoxy /alumina composite with submicron inclusions '', journal of material science, vol.39, (2004). 11r. j. crawford," plastic engineering", 2 nd ed., pergamonl press, u.k, (1987). 12d. r. askeland & p. p. phule ," the science & engineering of materials"4 th ed., (2003). 13b. r. sanders & t. l. weintraub, " matel hand book mechanical testing " ,vol.8 , 9 th ed. ,usa, (1985). 14n. g. mccrum, c. p. buckley & c. b. bucknall "principles of polymer engineering", 2 nd ed., john wiley & sons, new york, (1997). 15annual book of astm standards, 1986, vol. 08.01, d2240-86. 16i. j. mccolm " ceramic science for materials technologists ", leonard hill, new york, 1983. 17a. c. moloney, h. h. kausch & h. r. beer, " review parameters determining the strength & toughness of particulate filled epoxide resins", journal of materials science, vol.22, no. 2, 1987. 18g. piatti,"advances in composite materials", applied science publishers ltd, 1978. 19j. spnoudakis & r. j. young, "crack propagation in a glass particlefilled epoxy resin", journal of materials science ,vol.19, 1984. ( 2007 )26-17 انظفحت 3. انؼذد 3.يجهت انخىارزيً انهنذسٍت، انًجهذ /ػهً حسٍن ػتٍىي . د 26 study of mechanical characteristics for polymer composite reinforced by particles of (al2o3) or (al) dr. ali hussein ataiwi dr.jawad kadhim uleiwi saad m. elia university of technology \ mat. eng.depart abstract a particulate polymer composite material was prepared by reinforcing with the aluminum oxide (al2o3) or aluminum (al) metallic particles with a particle size of (30) µm to an unsaturated polyester resin with a weight fraction of (5%, 10%, 15%, 20%). tensile test results showed the maximum value of elastic modulus reached (2400mpa.) in the case of reinforcing with (al) particles with weight fraction (20%) and (1500 mpa.) in the case of reinforcing with (al2o3) particles of the same weight fraction. when the impact and the flexural strength tests were done, the results showed that flexural strength (f.s), maximum shear stress (τmax), impact strength (gc) and fracture toughness (kc) were increased with the increase of weight fraction, where the results of the samples of (al) particles were higher than that of (al2o3) particles reinforced at a weight fraction of (20%) at ratios of (45.43%, 45.45%, 25%, 41%) respectively. while the hardness of the samples reinforced with (al2o3) particles was higher than that reinforced with (al) particles with a ratio of (2.82%) at a weight fraction of (20%). (microsoft word 26-37 \317 \343\344\354 \346\317 \307\343\355\321) this is an open access article under the cc by license : al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 18, no. 1, marh, (2022) p. p. 2637 enhancement of system security by using lsb and rsa algorithms muna m. hummady* ameer hussein morad** *,**department of information and communication engineering / al-khwarizmi college of engineering / university of baghdad/ iraq *email: muna@kecbu.uobaghdad.edu.iq **email: ameer@kecbu.uobaghdad.edu.iq )2022 march 9r 2021; accepted octobe 17received ( .0013https://doi.org/10.22153/kej.2022.0 abstract a steganography hides information within other information, such as file, message, picture, or video. a cryptography is the science of converting the information from a readable form to an unreadable form for unauthorized person. the main problem in the stenographic system is embedding in cover-data without providing information that would facilitate its removal. in this research, a method for embedding data into images is suggested which employs least significant bit steganography (lsb) and ciphering (rsa algorithm) to protect the data. system security will be enhanced by this collaboration between steganography and cryptography. keywords: cryptography, lsb, rsa, steganography. 1. introduction digital life witnessed an increase in information security. security procedures, particularly data communication, are compelled by the emergence of new technologies. the amount of data are exchanged over the internet has grown, so hqas the significance of network security. information security relies heavily on cryptography and steganography. figure (1) depicts the widest range of information security measures. one side of the coin is steganography, which hides the communication's tracks, while the other side employs cryptography to render it unintelligible. muna m. hummady al-khwarizmi engineering journal, vol. 18, no. 1, p.p. 2637 (2022) 27 fig. 1. information security techniques. steganography is a method of disguising communication by enclosing the secret message within a false message. a cover carrier, a hidden message, a stego key, and a stego carrier are all required components of the steganography process. text, audio, picture, and video are all function as cover carriers for the secret information they carry. the stego carrier is created by combining a cover carrier with an embedded message. additionally, the stego key is utilized as supplemental secret information, such as a password that the recipient uses to extract the message [1]. cryptography offers a variety of encoding strategies for ensuring security when communicating over a public network. a simple example of cryptography is when a sender delivers a message that is originally in plaintext. prior to transmission across the network, the message is encrypted and transformed to cipher text. when the recipient receives this message, it is decrypted back into plaintext [1]. many mechanisms and algorithms are appeared in researches for combining these techniques for high level information security on open communication channel. m. gajalakshmi and r. vidya (2018) [1] and mustafa s.t et al (2019) [2], are review different approaches on process of hiding information in multimedia (such as text, image, movies, or sound). these approaches are merging two security mechanisms (cryptography and steganography) to achieve two levels of information security. manoj k. r. and et al (2017) [3] proposed hybrid steganographic model based on both steganography and cryptography. the model is designed depending on the strength of conventional 3-data encryption standard (des) and discrete wavelet transform (dwt) to improve quality of image and security. dheyab s. ibrahim (2019) [4], propose an algorithm to increase the security of data using two levels of encryption. the first level of security is done by using des & rsa algorithms. while the second level is to enhance the security by using lsb algorithm in order to hide these encrypted data inside edges of color images. security systems information hiding information encryption (cryptography) robust fragile video steganography watermarking technical linguistic visible imperceptible fingerprint images audio text asymmetric two cipher keys (public, private) symmetric one cipher key muna m. hummady al-khwarizmi engineering journal, vol. 18, no. 1, p.p. 2637 (2022) 28 marwa e. saleh and et al (2016) [5], propose a technique for both data security using cryptography and steganography techniques. this technique used to increase the information security. the first step is to encrypt the secret data using the advanced encryption standard (aes_mpk) algorithm. after that, the encrypted data has been hidden in gray image by using pvd-mpk and msldip-mpk methods. shambhavi u and et al (2015) [6], propose a combination of two types of steganography (audio and image). the aim of this work is to hide secret message (data) in an audio and image of a video file. the video has many frames inside both the image and audio. this proposes can select anyone of these frames for hiding secret data. two algorithms can be used for this purpose. these algorithms are 4lsb for image steganography and phase coding algorithm for audio steganography. ameer h. morad and hatem nahi mohaisen (2016) [7,8], the article presents hiding system based on steganography using cover video and watermarking techniques to provide both of confident and authentication. the hiding process is done in random fashion use lsb method to embed and distribute the message and watermark on many video frames. finally, mustafa sabah taha et al (2019) [9] review several ways of combining steganographic and cryptographic techniques to achieve a hybrid system and state some of the differences between cryptographic and steganographic techniques. in this paper, the proposed system merges both the cryptography and steganography techniques to make the transmission of secret information (text or image) more secured. this is done, at sender side, by encrypted the secret information using rsa encipher before hiding it into cover image. the lsb method is used to hide the secret information into cover image to obtain stego image. at receiver side, firstly extract the encrypted secret information from stego image, then decrypt it by rsa decipher to retrieve the original secret information. 2. the rsa algorithm (rivest-shamiradleman) asymmetric cryptography is rsa [10, 11]. it is frequently used to protect sensitive data, such as that transmitted over the internet. rsa encrypts messages use both public and private keys. the key that is used to encrypt and decrypt a communication is the inverse of the key used to encrypt it. this is a critical reason for rsa's popularity as the most extensively used asymmetric algorithm. the rsa algorithm ensures the secrecy, integrity, authenticity, and irreproducibility of electronic communications and data storage. 3. lsb (least significant bit) the transform domain and the spatial domain are too widely used to embed approaches in image steganography [12]. in the spatial domain, the secret data is directly incorporated in the cover image pixels' lsbs (least significant bits).the lsb method is the most common method used to hide the secret messages into a covered image. the (lsb) is easy to understand and relatively fast in the process of inserting secret information into cover image. it is only modify the low weight bits in the insertion process, so the difference between the stego image and the original image will not be noticeable to any person who views the image. many methods and procedures are proposed by researchers for applying lsb in applications such as insertion individually or combination in one or more of three least weight bits directly or in random fashion [13, 14]. 4. evaluation criteria (measurements) the evaluation of hiding process is done to measure the amount of differences between the stego image and the cover image. this requires measuring the quality of the stego image. those measures are mean square error, similarity test and peak signal-to-noise ratio. mean square error (mse) is a statistical term that refers to the mean or average of the square of the difference between actual and estimated values. mse is utilized in this study to identify the difference between the cover and stego images [8, 9]. ��� = 1�� � ��� − � � �� � �� … (1) where x and y are the image coordinates. m and n are the number of rows and columns in the input images. sxy and cxy are pixel gray (or color) values at x y coordinate in the generated stego-image and the covered image respectively. the content of the image hidden information must be embedded using the image steganography system in order not change the quality of the image. muna m. hummady al-khwarizmi engineering journal, vol. 18, no. 1, p.p. 2637 (2022) 29 psnr is the maximum signal to noise ratio in the stego image. psnr is commonly used to quantify reconstruction quality for images and video subject to lossy compression. the psnr value indicates the better quality of image; i.e. less distortion. ���� = 10 ����� ���� ! �"�#�$ ��%&'��"(& ��%&' ) = 10 ����� * � ∗ � ∗ (� − 1), ∑ ∑ �� − � ,� ��� �� . ⋯ (2) where: m*n: cover image size (height and width) in pixels. l: determine the number of gray scales in stego image (in this paper l=256). x, y: are image pixel coordinates. cxy: is cover image gray (or color) value at coordinate x and y. sxy: is stego image gray (or color) value at coordinate x and y. calculate the correlation between the stego image and the cover image to determine the similarity test. when the stego-image is perceived to be identical to the original cover-image, the correlation is one. correlations can be determined using the formula below. [15, 16]. ��' = ∑ ∑ �� − �̅ �� − �̅ � ��� �� 2∑ ∑ �� − �̅ ,�� − �̅ ,� ��� �� ⋯ (3) where �=̅ &�# �'�4 (�' 5�$�')6�$!& 7�' 5�6&' " ��& = 1� ∗ � � � � � �� � �� �=̅ &�# �'�4 (�' 5�$�')6�$!& 7�' (8&�� " ��& = 1� ∗ � � � � � �� � �� 5. cryptography vs. steganography it is possible to combine the encrypting message techniques by using cryptography and hiding the encrypted message using steganography. the resulting stego-image is transmitted without revealing that secret information which has been exchanged. even if an attacker defeats the steganographic technique and detects the message from the stego-object, the attacker still requires the cryptographic decoding key to decipher the encrypted message [19]. table (١) shows that both technologies have advantages and disadvantages [20]. table 1, advantages and disadvantages comparison steganography cryptography unknown message passing known message passing little known technology common technology technology still being developed for certain formats most algorithms known to government departments once detected message is known strong algorithm are currently resistant to brute force attack large expensive computing power required for cracking technology increase reduces strength 6. the proposed system individually, both steganography and cryptography techniques are insufficient for completing information security; therefore, the two techniques are being combined to achieve reliable and strong mechanism [1-9]. the proposed system based on combining these techniques. this can maintains the requirements used for security and robustness in order to transmit important information. the proposed system use cryptography technique based on rsa to encrypt the secret information then hidden it in the covering image using lsb steganography technique. the proposed system algorithm is illustrated in figure (2): sender side the secret information (message) is encrypted according to rsa to generate encrypted message muna m. hummady al-khwarizmi engineering journal, vol. 18, no. 1, p.p. 2637 (2022) 30 using public key. then both encrypted and public key are embedded into cover image. many procedures for hiding process are used for system evaluation. these procedures are covered in result paragraph. receiver side 1. both encrypted message and public key are extracted from stego image based on inverse lsb steganography. then use public key to generate private key according to rsa algorithm. 2. the original secret information is recovered by decrypting the extracted message. table (2), lists the algorithm steps for encrypting and embedding secret message (like text or image) into a cover image. table (3), lists the algorithm steps for extract and decrypt of the secret message from the stego image. fig. 2. proposed system structure. table 2, embed algorithm steps step process 1 read the cover image (gray or rgb color) and secret message (text or image) 2 convert the secret message (like text or image) to binary. the alphabets of text are convert into binary by encode them according to ascii code. the image pixel values are encoded according uint8 format. 3 generate public key using rsa criteria. 4 encrypt secret message using rsa encipher 5 replace one by one each lsb pixel of cover image (gray or rgb color) with secret message bits. 6 embedding public key into specific lsb pixel of cover image. after completing steps (5, 6), the result is stego image. 7 transmit stego image on web. muna m. hummady al-khwarizmi engineering journal, vol. 18, no. 1, p.p. 2637 (2022) 31 table 3, retrieve algorithm steps step process 1 read the stego image. 2 extract both encrypted secret message and public key from stego image. 3 use public key to generate private key according to rsa criteria. 4 decrypt the secret message using private key and decipher rsa. 5 convert each 8 bits into a character or an image pixel value to retrieve the original secret message like text or image. 6 display the secret message on screen. the proposed system is implemented using matlab. develop interactive screen shown in figure (3) to make the system easier to use. the interactive screen enable the user to read and display both the cover image and secret message (may be text or image). all embedded and extracted processes (such as generation of public key, encryption and decryption of secret message, and stego image generation, are all done directly by on clicking on specific bottoms. also, all the evaluation measurements, such as histograms, psnr and correlation, are calculated and displayed. a) embed text into image. muna m. hummady al-khwarizmi engineering journal, vol. 18, no. 1, p.p. 2637 (2022) 32 b) embed image into image. fig. 3. interactive display screen for the proposed system. 7. results to evaluate the system, select a cover image: rgb color of size 1024x768 or 768 kb which is sufficient as a hidden media. the system is tested to hidden both text and images. the hiding process is done in different ways as shown: 1. firstly, hiding secret message bits one by one into a one bit of pixels of cover image like in 1st lsb, 2nd lsb, 3rd lsb or 8th lsb. 2. secondly, hiding randomly in one of 3 first lsb (1st, 2nd, 3rd bit lsb). for each hiding process, psnr and correlation are calculated as shown in table (٤) and table (٥). also the three histograms of r, g, and b colors for both cover image and stego image are drawn. the evaluation results for hidden secret text of 104 kb are shown in figure (4). while the evaluation results for hidden secret color image of (98.3 kb) are shown in figure (5). table 4, psnr and correlation results for hidden secret text of (104 kb) image cover image size hidden image size psnr correlation 1 1024*768 1024*104 1st bit lsb 52.8095 0.999955 2 1024*768 1024*104 2nd bit lsb 46.5139 0.999981 3 1024*768 1024*104 3rd bit lsb 40.4909 0.999241 4 1024*768 1024*104 1st, 2nd, 3rd bit lsb 44.3691 0.999689 5 1024*768 1024*104 8th bit lsb 10.6935 0.386587 table 4, psnr and correlation results for hidden secret color image of (98.3 kb) image cover image size hidden image size psnr correlation 1 1024*768 1024*98.3 1st bit lsb 53.0849 0.999958 2 1024*768 1024*98.3 2nd bit lsb 46.7707 0.999822 3 1024*768 1024*98.3 3rd bit lsb 40.7585 0.999288 4 1024*768 1024*98.3 1st, 2nd, 3rd bit lsb 44.0844 0.999668 5 1024*768 1024*98.3 8th bit lsb 10.7022 0.383604 muna m. hummady al-khwarizmi engineering journal, vol. 18, no. 1, p.p. 2637 (2022) 33 cover image 1st bit lsb stego image psnr= 52.8095 correlation= 0.999955 2nd bit lsb stego image 3rd bit lsb stego image psnr= 46.5139 correlation= 0.999981 psnr= 40.4904 correlation= 0.999241 1st, 2nd, or 3rd bit lsb stego image 8th bit lsb stego image psnr=44.3691 correlation= 0.999689 psnr= 10.6935 correlation= 0.386587 fig. 4. evaluation results for hidden secret text of (104 kb). muna m. hummady al-khwarizmi engineering journal, vol. 18, no. 1, p.p. 2637 (2022) 34 cover image 1st bit lsb stego image psnr= 53.0849 correlation= 0.999958 2nd bit lsb stego image 3rd bit lsb stego image psnr= 46.7707 correlation= 0.999822 psnr= 40.7585 correlation= 0.999288 1st, 2nd, or 3rd bit lsb stego image 8th bit lsb stego image psnr=44.0844 correlation= 0.999668 psnr= 10.7022 correlation= 0.383604 fig. 5. evaluation results for hidden secret color image of (98.3 kb). muna m. hummady al-khwarizmi engineering journal, vol. 18, no. 1, p.p. 2637 (2022) 35 8. conclusion after studying the proposed stego-system, steganography message can be embedded into digital images in ways that are imperceptible to the human eye. in other words, a stego-image that is generated by the present algorithm has to be normal for human vision and cannot be detected to avoid visual attack. the results indicate that the suggested steganography system is more secure as a result of the use of the rsa encryption. however, the time required to embed/extract the secret message is increased as a result of the encryption/decryption computation. clearly, the results indicate that there do not notice any change in quality between cover image and stego image when embed the secret message in low lsb: 1st lsb, 2nd lsb, or 3rd lsb of cover image. whenever increasing the amount of data stored is increased, the level of lsb increased. also the value of psnr and correlation decreased gradually and this means that the cover image quality is decreased (small increasing in distortion). after comparing histogram of the cover image with the stego image, it is quite clear that histogram of stego image is almost similar to cover image with a change of only last bit of pixels. so this method is capable of producing a secret embedded image that is totally indistinguishable from the original image by the human eye and can’t be detected by histogram analysis method. 9. references [1] m. gajalakshmi and r. vidya, “a review on data hiding using cryptography and steganography,” international journal of computing algorithm, vol. 07, issue: 01, pp. 24-28, june 2018. [2] mustafa s. t., mohd s.m.r., sameer l., mohammed m.h., hassanain m. a., “combination of steganography and cryptography: a short survey,” 2nd international conference on sustainable engineering techniques (icset), doi:10.1088/1757-899x/518/5/052003, 2019. [3] manoj k. r., dinesh g. and naveen h., “data hiding in image using cryptography and steganography: an investigation,” international journal of advanced research in computer science, vol. 8, no. 7, pp. 953-956, july – august 2017. [4] dheyab salman ibrahim, “enhancing cloud computing security using cryptography & steganography,” iraqi journal of information technology, vol. 9, no. 3, 2019. [5] marwa e. saleh, abdelmgeid a. aly, fatma a. omara, “data security using cryptography and steganography techniques,” (ijacsa) international journal of advanced computer science and applications, vol. 7, no. 6, pp. 390-397, 2016. [6] shambhavi u. burge, nitin a. sawant, swapnil d. choudhari, priyanka a. sonkusare, “secure data hiding using cryptography and lsb techniques,” international journal of advanced research in computer engineering & technology (ijarcet), vol. 4, issue 10, pp. 3863-3870, oct. 2015. [7] ameer h. morad, hatem nahi mohaisen, “secret message hiding randomly in video,” international journal of advancements in computing technology (ijact), vol. 8, no. 3, june 2016. [8] hatem nahi mohaisen, ameer h. morad, “secure information using steganography and watermarking,” iraqi journal of science, vol. special issue part-a, pp. 112-128, 2016. [9] mustafa s. taha, et al, “combination of steganography and cryptography: a short survey,” 2nd international conference on sustainable engineering techniques (icset), appear in iop conf. series: materials science and engineering 518, 2019. [10] shireen nisha, mohammed farik, “rsa public key cryptography algorithm – a review,” international journal of scientific & technology research, vol. 6, issue 07, pp. 187-191, july 2017. [11] dindayal mahto, dilip kumar yadav, “performance analysis of rsa and elliptic curve cryptography,” international journal of network security, vol. 20, no. 4, pp. 625-635, july 2018. [12] divya.a1, s.thenmozhi, “steganography: various techniques in spatial and transform domain,” international journal of advanced scientific research and management, vol. 1, issue 3, march 2016. [13] ammar awad, “a survey of spatial domain techniques in image steganography,” journal of education college wasit university, vol. 26, jan. 2018. [14] marwa m. emam, abdelmgeid a. aly, andfatma a. omara, “an improved image steganography method based on lsb technique with random pixel selection,” muna m. hummady al-khwarizmi engineering journal, vol. 18, no. 1, p.p. 2637 (2022) 36 (ijacsa) international journal of advanced computer science and applications, vol. 7, no. 3, pp. 361-366, 2016 [15] harpreet kaur and jyoti rani, “a survey on different techniques of steganography,” matec web of conferences, doi: 10.1051/ 57, 02003, 2016. [16] s. udhayavene∗, aathira t. dev and k. chandrasekaran, “new data hiding technique in encrypted image: dkl algorithm (differing key length),” procedia computer science 54, pp. 790 – 798, 2015. [17] yifeng sun, fenlin liu, “selecting cover for image steganography by correlation coefficient,” 2010 second international workshop on education technology and computer science, 2010. [18] anita pradhan, et al., “performance evaluation parameters of image steganography techniques,” international conference research advances in integrated navigation systems (rains), 2016. [19] s. tanako, k. tanaka and t. sugimura, “data hiding via steganographic image transformation,” ieice trans. fundamentals, vol. e83-a, pp. 311-319, feb. 2000. [20] haripriya rout, brojo kishore mishra, “pros and cons of cryptography, steganography and perturbation techniques,” iosr journal of electronics and communication engineering (iosr-jece), e-issn: 22782834, p.p. 76-81. ) 2022( 2637، صفحة 1العدد، 18مجلة الخوارزمي الهندسية المجلدمنى مصطفى حمادي 37 ) (lsa & rsa امن النظام باستخدام خوارزميات تحسين وتعزيز **مير حسين مرادأ *منى مصطفى حمادي قسم هندسة المعلومات واالتصاالت/ كلية الهندسة الخوارزمي/ جامعة بغداد*،** muna@kecbu.uobaghdad.edu.iq :البريد االلكتروني* ameer@kecbu.uobaghdad.edu.iq :البريد االلكتروني** الخالصة ضمن معلومات أخرى. علم التشفير هو علم تحويل المعلومات قد تكون ملًفا أو رسالة أو صورة أو فيديوالتي إخفاء المعلوماتيقوم بإخفاء المعلومات علم في بيانات الغالف دون من نموذج قابل للقراءة إلى نموذج غير قابل للقراءة لشخص غير مصرح له. تكمن المشكلة الرئيسية في النظام االختزالي في التضمين ) والتشفير lsbتم اقتراح طريقة لتضمين البيانات في الصور تستخدم أسلوب إخفاء البايت األقل أهمية ( البحث،تقديم معلومات من شأنها تسهيل إزالتها. في هذا لمعلومات والتشفير. ) لحماية البيانات. سيتم تعزيز أمان النظام نتيجة لهذا التعاون بين علم إخفاء اrsa(خوارزمية al-khwarizmi engineering!!! journal al-khwarizmi engineering journal, vol. 6, no. 1, pp 48 56 (2010) synthetic sacks as reinforced fibers in the thermosetting composites mukheled a. hussien* falak o. abass** raghad o. abass*** *, ** environmental research center /university of technology * email: mukheled@yahoo.com *** department of material engineering /university of technology (received 19 may 2009: accepted 23 november 2009) abstract this study was carried out to investigate the preparation of thermosetting polymeric blend consisting of three adhesive types, namely: epoxy, polyvinyl formal (pvf) and unsaturated polyester. both of epoxy and pvf were used as a matrix-binder at fixed weight. whilst unsaturated polyester was used at different weights and added to the matrix so as to produce prepared epoxy-pvf-unsaturated polyester blend. several experiments were performed at different operating conditions, mixing speed and time at room temperature to identify the most favorable operating conditions. the optimum mixing speed and mixing time for the prepared blend were 500rpm and 5 minutes respectively. solid wastes-synthetic sack fibers from high volume, low cost, renewable fiber sources have been used as environmentally friendly alternatives to reinforcing fibers in composites. many mechanical and thermal tests were carried out of the prepared blend at different weighted ratios. the optimum weighted ratio of the prepared blend for the untreated samples was characterized by the hardness and bending deflection properties and it was 0.40w/w, while for impact strength and thermal conductivity properties was 0.20w/w respectively. at these optimum weighted ratios of untreated samples with sack fibers, the maximum values of hardness and impact strength properties were 95 shore and 2.25j/cm2 respectively. on the other hand, the minimum bending deflection and thermal conductivity properties values were found to be 4mm and 0.01094w/cm.oc respectively. they showed the best bonding forces and physical interaction between two concentrations of matrix and unsaturated polyester adhesives. treated samples of sack fibers reinforced composites at their optimum weighted ratio showed better fiber-matrix interaction as observed from the experimental results leading to enhance and improve the mechanical (hardness, impact strength, and bending deflection) and thermal (thermal conductivity) properties when compared to the untreated sample. these improvements in treated samples with two layers of sack fibers were predominant. keywords: epoxy, polyvinyl formal, unsaturated polyester, sack fibers and thermo-mechanical properties. 1. introduction composites are materials that comprise strong load carrying material, known as reinforcement, imbedded in weaker material, known as matrix. reinforcement provides strength and rigidity, helping to support structural load. the matrix or binder, organic or inorganic, maintains the position and orientation of the reinforcement [1]. in polymer composites, the binder material is a polymer. the binder, or matrix, surrounds the reinforcing elements which may be plates, particles or fibers and which are usually added to improve mechanical properties such as stiffness, strength and toughness of the matrix material [2, 3]. thermoset is a hard and stiff crosslinked material that does not soften or become moldable when heated. several types of polymers have been used as matrices for natural fiber composites [4]. common thermosetting polymer resins are of high performance in composites which are epoxy, unsaturated polyester, vinyl ester, and phenolic [5]. unsaturated polyester is extremely versatile in properties and applications and has been a popular thermoset used as the polymer matrix in composites. it is widely produced industrially as it possesses many advantages compared to other mukheled a. hussien!! al-khwarizmi engineering journal, vol.6, no.1, pp 48 -56 (2010) 49 thermosetting resins including room temperature cure capability, good mechanical properties and transparency [6]. the reinforcement of polyesters with fibers has been widely reported. some of the promising systems are polyester-sisal [7], polyester-coir [8], polyester-straw [9] and polyester-cotton-kapok [10]. the mechanical properties of a natural fiberreinforced composite depend on many parameters, such as fiber strength, modulus, fiber length and orientation, in addition to the fiber-matrix interfacial bond strength. a strong fiber-matrix interface bond is critical for high mechanical properties of composites. a good interfacial bond is required for effective stress transfer from the matrix to the fiber whereby maximum utilization of the fiber strength in the composite is achieved [11]. the composite properties were greatly influenced by the technique as well as the processing method used. processing produces a great variation on the dimension and dispersion of the fiber within the composite. understanding the relationship between processing and the properties of the composites is important to obtain materials with optimized performance [12]. similar observation was found by george et al. [13] who noticed that factors like processing conditions/techniques have significant influence on the mechanical properties of fiber reinforced composites. detailed studies have been done on the impact resistance of short fiber reinforced composites [14, 15, 16]. they showed that the impact resistance of fiber-reinforced composite depends on fiber rigidity, interfacial stress resistance and fiber aspect ratio. the strength of the matrix, the weakest part of the material, should be related to the failure process. the involvement of fibers in the failure process is related to their interaction with the crack formation in the matrix and their stress transferring capability. the total energy dissipated in the composite before final failure occurs is a measure of its impact resistance. the total energy absorbed by the composite is the sum of energy consumed during plastic deformation and the energy needed for creating new surfaces. nielsen [17] observed that fibers have a significant effect on the impact resistance through the principle of stress transfer. when an impact load is applied perpendicular to the reinforcing fibers, good fiber-matrix adhesion is required for an even moderate impact strength. impact resistance is the ability of a material to resist breaking under a shock loading or the ability to resist fracture under stress applied at high speed. shah [18] showed that the impact properties of the polymeric materials are directly related to the overall toughness of the material. toughness is defined as the ability of the polymer to absorb applied energy. rajulu et al. [19] investigated the effect of untreated and treated bamboo fibers coating with epoxy, unsaturated polyester and their blends on the mechanical property (tensile strength). they found that the blend coated fibers had higher tensile strength. this was attributed to the hydrogen bonding between the unsaturated polyester and epoxies group. another study carried out by rajulu et al. [20] studied the chemical resistance and tensile strength properties of epoxy/polycarbonate blend coated bamboo fibers and suggested that these are favorable materials for making the composites. park et al. [21] observed an increase in the physical properties when 5% of the weight of the unsaturated polyester was used in the epoxy and unsaturated polyester blend. similarly harani et al. [22] have used unsaturated polyester for toughening the epoxy resin. the aim of the present work is to find the optimum weighted ratio of prepared blend in the weighted formula [polyester/(epoxy+pvf)] as (w/w) by using thermo-mechanical properties as well as to ascertain whether or not the three types of thermosetting-sack system can be effectively employed for making the composites. 2. experimental work materials three different types of chemical adhesives: epoxy, polyvinyl formal (pvf) and unsaturated polyester with technical specifications shown in table 1 as well as synthetic sacks fibers that are used in the storage of sugar, rice and flour were applied as a reinforced composite material in this work. methods preparation of reinforced composite material sack fibers were first cleaned, washed thoroughly with tap water and left in the open air until dryness. the dried sack fibers of one layer were cut to the rectangular cross-section with a mukheled a. hussien!! al-khwarizmi engineering journal, vol.6, no.1, pp 48 -56 (2010) 50 width of 15mm, a length of 170mm and a thickness of 0.5mm to be used for the bending and impact tests, and to the circular cross-section with diameter (30mm) and thickness 0.5mm to be used for the hardness and thermal conductivity tests. table 1, technical specifications of epoxy, pvf and unsaturated polyester resin epoxy resin polyvinyl formal (pvf) resin compressive strength: > 72 n/mm2 @7 days @20oc bs 6319 formaver 15/95e free flexural strength: > 60 n/mm2 @35oc bs 6319 flowing powder, bdh tensile strength: > 25 n/mm2 bs 6319 m.w. 24000 to 40000 pot life: 85 minutes @20oc pvf 82% specific gravity: 1.04 pvoh 5 to 6% viscosity: 1.0 poise @35oc pvac 9.5-13% min. application temperature: 5oc viscosity in 15% solution 60/40 toluene/ethanol at 25oc: 3000 to 4500cp unsaturated polyester resin appearance: transparence styrene wt%:32% viscosity at 25oc: 1000 cp specific gravity: 1.15 gelatinization time: 6 min. preparation of the blend a) preparation of epoxy blend fixed weight of epoxy resin (17.5g) was added to a fixed quantity of hardener (5.8g) and agitated at constant mixing speed (500rpm) using a stirrer (labinco bv, model l-81, netherland), for a constant period of mixing time (15 minutes) at room temperature. b) preparation of pvf blend fixed weight of pvf resin (0.1g) in the form of solid phase (powder) was added to a fixed quantity of solvent (2.3g) and agitated for fully dissolving the pvf material at constant mixing speed and time (700rpm, 15 minutes) using the same stirrer at room temperature. c) preparation of unsaturated polyester blend different weights of unsaturated polyester varied from (5 to 25g) with its varied quantities of hardeness from (0.1 to 0.5g) and agitated at constant mixing speed and time (500rpm, 15 minutes) using the same stirrer at room temperature. d) preparation of (epoxy-pvf-unsaturated polyester) blend all blends of epoxy, pvf and unsaturated polyester were put together and agitated thoroughly at constant mixing speed and mixing time (500rpm and 5 minutes) respectively at room temperature and divided into two portions. these portions were directly put in moulds of tests and designated as untreated samples-without sack fibers (w.s.). treated samples of sack fibers for one and two layers are designated as (o.s.), (t.s.) respectively and were put in tests moulds and coated until saturated with the prepared blend. all prepared samples (untreated and treated) were left in the open air for one day at room temperature before conducting the laboratory tests. note that epoxy-pvf-unsaturated polyester blend is designated as a prepared blend in the weighted formula (polyester/(epoxy+pvf)) as (w/w) and it is at zero weight of polyester blend; i.e. (epoxy+pvf) blend is only designated as standard ratio (0w/w) of prepared blend in the experiments. 3. methodology experiments were performed to characterize the thermo-mechanical properties of the thermosetting polymeric composites. the untreated and treated samples of the prepared blend were loaded into the instruments so as to investigate the mechanical and thermal tests. the impact strength was determined using charpy impact instrument (time testing machine, xju-22, mukheled a. hussien!! al-khwarizmi engineering journal, vol.6, no.1, pp 48 -56 (2010) 51 pendulum, time group, 2007, inc., usa). the bending deflection was determined by using phywe instrument (three point bending tester according to astm d790). while the hardness property was determined by using w lestor amsler, harkeprufer, din 53505, iso r868, shore d). on the other hand, the thermal conductivity test of prepared blend was achieved by using lee's disk instrument (kocyigit electronic, dc 0-30 volt, 6 amperes; uk). the thermal conductivity for the treated and untreated samples was calculated by using the following equations: e = p/ r[r(t1+t3) + 2(d1t1+0.5ds(t1+t2) + d2t2+ d3t3] k = e ds [t1 + 2t1 (d1 + 0.5ds)/r + t2ds/r] / (t2 – t1) where e = loss in heat per unit area in (w/cm2.oc) p = supplied power in (w) r = radius of disk in (cm) d1, d2, d3 = thickness of disks in (cm) ds = thickness of specimen in (cm) t1, t2, t3 = measured temperatures of disks no. 1, 2, and 3 in (oc) k = thermal conductivity in (w/cm.oc) 4. results and discussion investigation of the optimum weighted ratio of prepared blend mechanical and thermal tests were carried out at different weighted ratios (0, 0.20, 0.40, 0.60, 0.79 and 0.99w/w) of prepared blend for untreated samples-without sack fibers (w.s.) to investigate the optimum weighted ratio of (epoxy-pvfunsaturated polyester) blend. 4.1.1. mechanical tests a) hardness test the effect of untreated samples at different weighted ratios of prepared blend on the mechanical property, hardness in shore is shown in figure 1. it seems clearly that the values of hardness property of untreated samples increased from 66 to 95 shore with increasing the ratios of prepared blend from 0 to 0.40w/w and decreased to 78 shore at 0.99w/w. this behavior is due to the increase in the ratios of prepared blend from standard ratio (0w/w) to 0.40w/w which was associated with an increase in the concentration of unsaturated polyester blend that has been a good mechanical properties [6] to reach the strong chemical interaction and maximum bonding forces between two concentrations of matrixbinder (epoxy and pvf blends) and unsaturated polyester blend at 0.40w/w that represented the ability to absorb the applied energy [18]. similar observation was found by harani et al. [22] who used unsaturated polyester for toughening the epoxy resin. on the other hand, it can be clearly seen from figure 1 that the maximum hardness value of untreated sample occurred at 0.40w/w that is designated as the optimum weighted ratio for hardness test. 60 65 70 75 80 85 90 95 100 0 0.2 0.4 0.6 0.8 1 1.2 weighted ratios of prepared blend (w/w) h a rd n es s (s h o re ) fig.1. effect of untreated samples at different weighted ratios of prepared blend on the hardness property. b) impact strength test figure 2 shows the effect of untreated samples on the impact strength property in j/cm2 at different weighted ratios of prepared blend. it is clear to note that the maximum impact strength value of untreated sample occurred at the weighted ratio of prepared blend of 0.20w/w. this ratio showed a better chemical interaction and maximum bonding forces between the epoxide group of the matrix-binder and unsaturated polyester blend for the three thermosetting adhesives [2, 3]. on the other hand, the addition of unsaturated polyester to matrix blend led to increase the strength of matrix and overall impact properties of prepared blend [18].the weighted ratio at 0.20w/w is designated as the optimum weighted ratio for impact strength test. mukheled a. hussien!! al-khwarizmi engineering journal, vol.6, no.1, pp 48 -56 (2010) 52 1.3 1.5 1.7 1.9 2.1 2.3 2.5 0 0.2 0.4 0.6 0.8 1 1.2 weighted ratios of prepared blend (w/w) im p ac t s tr en g th ( j/ cm 2 ) fig.2. effect of untreated samples at different weighted ratios of prepared blend on the impact strength property. 2 4 6 8 10 12 14 16 18 20 0 0.2 0.4 0.6 0.8 1 weighed ratios of prepared blend (w/w) b e n d in g d ef le ct io n ( m m ) fig.3. effect of untreated samples at different weighted ratios of prepared blend on the bending deflection property. c) bending deflection test the effect of untreated samples on the mechanical property, bending deflection in mm, at different weighted ratios of prepared blend is shown in figure 3. it seems clearly that the values of bending deflection property of untreated sample decreased from 19 to 4mm with increasing the ratios of prepared blend from standard ratio to 0.40w/w and increased to 6mm at 0.99w/w. it seems that the ratio of prepared blend at 0.40w/w showed a better resistance and lower bending distortion values. this can be related to the hydrogen bonding between three thermosetting polymeric adhesives of blends which promotes close packing at molecular level [19]. the results provided evidence that the prepared blend at 0.40w/w reached to the optimum weighted ratio for bending deflection test. d) thermal test figure 4 shows the effect of untreated samples at different weighed ratios of prepared blend on the thermal conductivity property in w/cm.oc. it seems clearly that the maximum value of the thermal conductivity of prepared blend occurred at the weighted ratio of 0w/w; i.e. the standard ratio of prepared blend. the minimum value of the thermal conductivity of prepared blend correspond to the weighted ratio of 0.20w/w. on the other hand, experimental results showed that the thermal conductivity of prepared blend at different weighted ratios is smaller than that of standard weighted ratio. this is due to thermal resistance of unsaturated polyester adhesive that led to increase the overall thermal resistance of the prepared blend [6]. the prepared blend at 0.20w/w is designated as the optimum weighted ratio for thermal conductivity test. 0.01 0.011 0.012 0.013 0 0.2 0.4 0.6 0.8 1 1.2 weighted ratios of prepared blend (w/w) t h e rm a l c o n d u c ti vi ty ( w /c m .o c ) fig.4. effect of untreated samples at different weighted ratios of prepared blend on the thermal conductivity property. investigation of the reinforced composite material 4.2.1. mechanical tests a) hardness test table 2 shows the effect of untreated (w.s.) and treated samples with sack fibers (o.s., t.s.) on the hardness property at standard and optimum weighted ratios of prepared blend. at the standard weighted ratio, the percentage values of hardness for treated sample with sack fibers increased by 16 and 22% respectively compared mukheled a. hussien!! al-khwarizmi engineering journal, vol.6, no.1, pp 48 -56 (2010) 53 to that of untreated sample. while at the optimum weighted ratio, they increased by 29 and 41% respectively. on the whole, it is observed that the treated sample with sack fibers at standard and optimum weighted ratios of prepared blend showed a better mechanical strength of the composite material and a better physical interaction with prepared blend. this result is in agreement with that reported by nielsen [11] who attributed that to the strong fiber-matrix interface bond for giving high mechanical properties. table 2, effect of untreated and treated sample on the hardness property at standard and optimum weighted ratios of prepared blend. weighted ratios of prepared blend (w/w) percentage increase of hardness in (shore) for treated samples o.s.% t.s.% standard (0) 16 22 optimum (٠.20) 29 41 b) impact strength test table 3 shows the effect of untreated (w.s.) and treated samples with sack fibers (o.s., t.s.) on the impact strength property at the standard and optimum weighted ratios of prepared blend. table 3, effect of untreated and treated sample on the impact strength property at standard and optimum weighted ratios of prepared blend. weighted ratios of prepared blend (w/w) percentage increase of impact strength in (j/cm2) for treated samples o.s.% t.s.% standard (0) 9 13 optimum (٠.40) 16 26 compared to untreated samples, the impact strength percentage values of treated samples with sack fibers for one layer (o.s.) and two layers (t.s.) increased by 9 and 13% respectively for standard ratio. whilst, they increased by 16 and 26% respectively for the optimum weighted ratio. treated samples of sack fibers with two layers (t.s.) showed better fiber reinforced composites as observed from table 3. this can be attributed to the strong physical interaction between the prepared blend of thermosetting and reinforced composite fibers that led to increase in the strength and toughness between them [14]. the sack fibers with two layers (t.s.) effect on the impact strength property was predominant. mechanical properties of a fiber-reinforced composite depend on many parameters, such as fiber strength, modulus, fiber length and orientation, in addition to the fiber-matrix interfacial bond strength [11]. c) bending deflection test table 4 shows the effect of untreated (w.s.) and treated samples with sack fibers (o.s., t.s.) at standard and optimum weighted ratio of prepared blend on the bending deflection in mm. the percentage values of bending deflection for treated sample with sack at standard weighted ratio were improved by 16 and 25% respectively compared to that of untreated sample. while at the optimum ratio, they improved by 29 and 41% respectively. on the other hand, the treated sample with sack fibers led to enhance the bending deflection property of the treated sample for both standard and optimum weighted ratios. this is due to the excellent mechanical strength of the prepared blend and reinforced composite material. these findings are in agreement with those reported by karnani et al [11] who showed that the mechanical properties of a natural fiber-reinforced composite depend on the fiber-matrix interfacial bond strength. a strong fiber-matrix interface bond is critical for high mechanical properties of composites. rajulu et al. [16] found that the blend (epoxy and polyester) coated fibers (bamboo) had higher mechanical properties. they attributed that to the hydrogen bonding between the unsaturated polyester and epoxies group. table 4, effect of untreated and treated sample on the bending defection at standard and optimum weighted ratios of prepared blend. weighted ratios of prepared blend (w/w) percentage increase of bending deflection (mm) for treated samples o.s.% t.s.% standard (0) 16 25 optimum (٠.20) 29 41 mukheled a. hussien!! al-khwarizmi engineering journal, vol.6, no.1, pp 48 -56 (2010) 54 d) thermal test the effect of untreated and treated samples with sack fibers on the thermal conductivity property in w/cm.oc at standard and optimum weighted ratios of prepared blend is shown in table 5. it is clear to note that the thermal conductivity of treated samples with sack fibers have lower percentage values and improved by 8 and 12% respectively when compared to those of the untreated samples. whilst at the optimum weighted ratio, they improved by 13 and 19% respectively compared to that of the untreated sample. it is generally observed that the improvement of thermal conductivity property for treated sample with two layers of sack fibers was predominant due to the best thermal resistance of them. this depends on processing conditions/ techniques that has significant influence on the mechanical properties of fiber reinforced composites [12, 13]. table 5, effect of untreated and treated sample on the thermal conductivity at standard and optimum weighted ratios of prepared blend. weighted ratios of prepared blend (w/w) percentage increase of thermal conductivity (w/cm.oc) for treated samples o.s.% t.s.% standard (0) 8 12 optimum (٠.40) 13 19 5. conclusions from the results presented, it can be concluded that: 1. the optimum mixing speed for the preparation of epoxy, unsaturated polyester and prepared blends was 500rpm while for pvf blend was 700rpm. the optimum mixing time for all blends was 15 minutes; except for prepared blend, it was 5 minutes. 2. the optimum weighted ratio of prepared blend for hardness and bending deflection properties was 0.40w/w. while for impact strength and thermal conductivity properties was 0.20w/w. 3. the maximum hardness and impact strength values of untreated samples occurred at the optimum weighted ratio of prepared blend were found to be 95 shore and 2.25 j/cm2 respectively. 4. the minimum bending deflection and thermal conductivity values of untreated samples occurred at the optimum weighted ratio of prepared blend were found to be 4mm and 0.01094 w/cm.oc respectively. 5. experimental results showed that treated samples with sack fibers led to enhance and improve in the mechanical and thermal properties when compared to the untreated sample. 6. the mechanical and thermal properties of composite were significantly influenced by the techniques used. the improvement of treated samples with two layers (t.s.) of sack fibers for both mechanical and thermal properties is predominant. 7. sack fibers can be used as an important source of fiber for composites and other industrial applications. 8. the above observations clearly indicate that the prepared blend of thermosetting (epoxypvf-unsaturated polyester) blend and solid wastes-sack fibers may be recommended as favorable materials for making the composites of three types of thermosetting-synthetic sacks system to satisfy both economical and ecological interests. 6. references [1] hull, d. and clyne, t.w. (1996). an introduction to composite materials. cambridge university press, cambridge. [2] d.h. mueller, a. krobjilowski, (2003), “new discovery in the properties of composites reinforced with natural fibers”, journal of industrial textiles, 33(2), 111-129. [3] h. lilholt, j.m. lawther, (2000), “comprehensive composite materials”, chapter 1.10, elsevier ltd. [4] sinha, r., (2000). outlines of polymer technology.prentice-hall by india private ltd. new delhi –10001. [5] a.k. bledzki, o. faruk, (2003), “wood fibre reinforced polypropylene composites: effect of fibre geometry and ccoupling agent on physico-mechanical properties”, applied composite materials, 10(6), 365-379. [6] sharifah, h.a., martin, p.a., simon, t.c. and simon, r.p. (2005). modified polyester resins for natural fiber composites. compos. sci. technol.65:525-535. mukheled a. hussien!! al-khwarizmi engineering journal, vol.6, no.1, pp 48 -56 (2010) 55 [7] pal, s., mukhophadhyay, d., sanyal s. and mukherjea, r. (1988). studies on process variables for natural fiber composites--effect of peap as interfacial agent. j. appl. polym. sci. 35: 973-985. [8] owolabi, o., czvikovszky, t. and kovacs, i. (1985). coconut fiber reinforced thermosetting plastics. j. appl. polym. sci. 30:1827-1836. [9] white, n. and ansell, m., (1983). strawreinforced polyester composites. j. mater. sci. 18:1549-1556. [10] mwaikambo, l. and bisanda, e. (1999). the performance of cotton/kapok fabricpolyester composites. polym. testing 18:181-198. [11] karnani, r., m. krishnan and r. narayan. (1997). biofiber-reinforced polypropylene composites. polymer engineering and science 37 (2): 476-483. [12] wang, b. thesis (2004). pre-treatment of flax fibers for use in rotationally molded biocomposites. university of saskatchewan, saskatoon. [13] george, j., m.s. sreekala and s. thomas. (2001). a review on interface modification and characterization of natural fiber reinforced plastic composites. polymer engineering and science 41 (9):1471-1485. [14] kau, h.t. (1990). a study of the impact behavior of chopped fiber reinforced composite. polymer composites 11 (5):253264. [15] jang, b. z., l.c. chen, l.r. hwang, j.e. hawkes and r.h. zee. (1990). the response of fibrous composites to impact loading. polymer composites 11 (3):144-157. [16] reed, p.e. and l. bevan. (1993). impact damage in a composite material. polymer composites 14 (4):286-291. [17] nielsen, l.e. (1974). mechanical properties of polymers and composites. vol. 2. new york, ny: marcel dekker, inc. [18] shah, v. (1998). handbook of plastics testing technology. 2nd ed. new york, ny: john wiley and sons. [19] a. varada ragulu, l. ganga devi, g. babu rao and lakshminaryana reddy. (2003). journal of reinforced plastics and composites, vol. 22, no. 11/2003. [20] varada ragulu, a., babu rao, g., lakshminaryana reddy. r. and sanjeevi (2001). journal of reinforced plastics and composites, 20: 335. [21] park, s.j., w.b. and lee, j.r. (1999). polymer j., 31: 28. [22] harani, h., fellahi, s. and barkar, m. (1999). j. appl.polym. sci., 71: 29. )2010( 56 48، صفحة 1، العدد 6مجلة الخوارزمي الھندسیة المجلد مخلد عامر حسین 56 لنسیجیة كألیاف تقویة مركبة مع اللواصق المتصلدةاألكیاس ا ***رغد أسامة عباس **فلك أسامة عباس *مخلد عامر حسین الجامعة التكنولوجیة/ مركز بحوث البیئة ** , * mukheled@yahoo.com:البرید االلكتروني* الجامعة التكنولوجیة/ ھندسة الموادقسم *** الخالصة االیبوكسي والبولي فینیل فورمال والبولي استر غیر (ُنفذت ھذه الدراسة للتحري عن تحضیر مزیج یتكون من ثالثة لواصق بولیمریة متصلدة وھي ن ثابتة، بینما ُاستخدم الصق البولي استر غیر المشبع عند أوزان كرابط عند أوزا) االیبوكسي والبولي فینیل فورمال(تم ُاستخدام كل من الصقي ). المشبع ُنفذت مجموعة من التجارب عند ظروف ). االیبوكسي والبولي فینیل فورمال والبولي استر غیر المشبع(مختلفة وأضیف إلى الرابط إلنتاج المزیج المحضر زمن خلط للمزیج وقد وجدت أفضل سرعة و. ة لتحدید أفضل الظروف التشغیلیةعند درجة حرارة الغرف) سرعة الخلط وزمن الخلط(تشغیلیة مختلفة .على التوالي) دقائق ٥و (500rpmالمحضر عند المتواجدة بكمیات وفیرة وقلیلة الكلفة ومصدر متجدد لأللیاف كصدیق للبیئة وبدیل أللیاف التدعیم ) ألیاف أألكیاس النسیجیة(تم استخدام النفایات الصلبة ُحددت أفضل نسبة وزنیھ للمزیج . أجریت العدید من االختبارات المیكانیكیة والحراریة للمزیج المحضر عند نسب وزنیھ مختلفة. المواد المتراكبةفي قوة الصدمة والموصلیة (لخواص بینما ُوجدت). ٠.٤٠(w/wللنماذج غیر المعاملة، وقد ُوجدت ) الصالدة وتشویھ االنحناء(المحضر عن طریق خواص للمزیج المحضر عند ) الصالدة وقوة الصدمة(عند ھذه النسب الوزنیھ المثالیة للنماذج غیر المعاملة، وجدت أعلى قیم لخواص . (0.20w/w)عند ) الحراریة )95shore و(2.25j/cm2 لخواص اقل قیم وجدت بینما. على التوالي)4(د عن) تشویھ االنحناء والموصلیة الحراریةmm وw/cm.ocعلى )٠.٠١٠٩٤ .والبولي استر غیر المشبع) االیبوكسي والبولي فینیل فورمال(أظھرت ھذه الخواص أفضل قوى ترابط وتجاذب فیزیائي بین الصقي الرابط . التوالي قوى ترابط بین اللواصق واأللیاف والتي أدت إلى أظھرت النتائج العملیة للنماذج المعاملة بألیاف أألكیاس النسیجیة عند نسبھا الوزنیھ المثالیة أفضل ھذه . مقارنة مع النماذج غیر المعاملة) الموصلیة الحراریة(والحراریة ) وتشویھ االنحناء الصالدة وقوة الصدمة(تعزیز وتحسین الخواص المیكانیكیة .لنسیجیة كانت ھي السائدةالتحسینات التي طرأت على النماذج المعالجة باستخدام طبقتین من ألیاف أألكیاس ا p 60 65 70 75 80 85 90 95 100 0 0.2 0.4 0.6 0.8 1 1.2 weighted ratios of prepared blend (w/w) hardness (shore) 1.3 1.5 1.7 1.9 2.1 2.3 2.5 0 0.2 0.4 0.6 0.8 1 1.2 weighted ratios of prepared blend (w/w) impact strength (j/cm 2 ) 2 4 6 8 10 12 14 16 18 20 0 0.2 0.4 0.6 0.8 1 weighed ratios of prepared blend (w/w) bending deflection (mm) 0.01 0.011 0.012 0.013 0 0.2 0.4 0.6 0.8 1 1.2 weighted ratios of prepared blend (w/w) thermal conductivity (w/cm. o c) mukheled a. hussien al-khwarizmi engineering journal, vol.6, no.1, pp 48 -56 (2010) al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 6, no. 1, pp 48 56 (2010) synthetic sacks as reinforced fibers in the thermosetting composites mukheled a. hussien* falak o. abass** raghad o. abass*** *, ** environmental research center /university of technology * email: mukheled@yahoo.com *** department of material engineering /university of technology (received 19 may 2009: accepted 23 november 2009) abstract this study was carried out to investigate the preparation of thermosetting polymeric blend consisting of three adhesive types, namely: epoxy, polyvinyl formal (pvf) and unsaturated polyester. both of epoxy and pvf were used as a matrix-binder at fixed weight. whilst unsaturated polyester was used at different weights and added to the matrix so as to produce prepared epoxy-pvf-unsaturated polyester blend. several experiments were performed at different operating conditions, mixing speed and time at room temperature to identify the most favorable operating conditions. the optimum mixing speed and mixing time for the prepared blend were 500rpm and 5 minutes respectively. solid wastes-synthetic sack fibers from high volume, low cost, renewable fiber sources have been used as environmentally friendly alternatives to reinforcing fibers in composites. many mechanical and thermal tests were carried out of the prepared blend at different weighted ratios. the optimum weighted ratio of the prepared blend for the untreated samples was characterized by the hardness and bending deflection properties and it was 0.40w/w, while for impact strength and thermal conductivity properties was 0.20w/w respectively. at these optimum weighted ratios of untreated samples with sack fibers, the maximum values of hardness and impact strength properties were 95 shore and 2.25j/cm2 respectively. on the other hand, the minimum bending deflection and thermal conductivity properties values were found to be 4mm and 0.01094w/cm.oc respectively. they showed the best bonding forces and physical interaction between two concentrations of matrix and unsaturated polyester adhesives. treated samples of sack fibers reinforced composites at their optimum weighted ratio showed better fiber-matrix interaction as observed from the experimental results leading to enhance and improve the mechanical (hardness, impact strength, and bending deflection) and thermal (thermal conductivity) properties when compared to the untreated sample. these improvements in treated samples with two layers of sack fibers were predominant. keywords: epoxy, polyvinyl formal, unsaturated polyester, sack fibers and thermo-mechanical properties. 1. introduction composites are materials that comprise strong load carrying material, known as reinforcement, imbedded in weaker material, known as matrix. reinforcement provides strength and rigidity, helping to support structural load. the matrix or binder, organic or inorganic, maintains the position and orientation of the reinforcement [1]. in polymer composites, the binder material is a polymer. the binder, or matrix, surrounds the reinforcing elements which may be plates, particles or fibers and which are usually added to improve mechanical properties such as stiffness, strength and toughness of the matrix material [2, 3]. thermoset is a hard and stiff crosslinked material that does not soften or become moldable when heated. several types of polymers have been used as matrices for natural fiber composites [4]. common thermosetting polymer resins are of high performance in composites which are epoxy, unsaturated polyester, vinyl ester, and phenolic [5]. unsaturated polyester is extremely versatile in properties and applications and has been a popular thermoset used as the polymer matrix in composites. it is widely produced industrially as it possesses many advantages compared to other thermosetting resins including room temperature cure capability, good mechanical properties and transparency [6]. the reinforcement of polyesters with fibers has been widely reported. some of the promising systems are polyester-sisal [7], polyester-coir [8], polyester-straw [9] and polyester-cotton-kapok [10]. the mechanical properties of a natural fiber-reinforced composite depend on many parameters, such as fiber strength, modulus, fiber length and orientation, in addition to the fiber-matrix interfacial bond strength. a strong fiber-matrix interface bond is critical for high mechanical properties of composites. a good interfacial bond is required for effective stress transfer from the matrix to the fiber whereby maximum utilization of the fiber strength in the composite is achieved [11]. the composite properties were greatly influenced by the technique as well as the processing method used. processing produces a great variation on the dimension and dispersion of the fiber within the composite. understanding the relationship between processing and the properties of the composites is important to obtain materials with optimized performance [12]. similar observation was found by george et al. [13] who noticed that factors like processing conditions/techniques have significant influence on the mechanical properties of fiber reinforced composites. detailed studies have been done on the impact resistance of short fiber reinforced composites [14, 15, 16]. they showed that the impact resistance of fiber-reinforced composite depends on fiber rigidity, interfacial stress resistance and fiber aspect ratio. the strength of the matrix, the weakest part of the material, should be related to the failure process. the involvement of fibers in the failure process is related to their interaction with the crack formation in the matrix and their stress transferring capability. the total energy dissipated in the composite before final failure occurs is a measure of its impact resistance. the total energy absorbed by the composite is the sum of energy consumed during plastic deformation and the energy needed for creating new surfaces. nielsen [17] observed that fibers have a significant effect on the impact resistance through the principle of stress transfer. when an impact load is applied perpendicular to the reinforcing fibers, good fiber-matrix adhesion is required for an even moderate impact strength. impact resistance is the ability of a material to resist breaking under a shock loading or the ability to resist fracture under stress applied at high speed. shah [18] showed that the impact properties of the polymeric materials are directly related to the overall toughness of the material. toughness is defined as the ability of the polymer to absorb applied energy. rajulu et al. [19] investigated the effect of untreated and treated bamboo fibers coating with epoxy, unsaturated polyester and their blends on the mechanical property (tensile strength). they found that the blend coated fibers had higher tensile strength. this was attributed to the hydrogen bonding between the unsaturated polyester and epoxies group. another study carried out by rajulu et al. [20] studied the chemical resistance and tensile strength properties of epoxy/polycarbonate blend coated bamboo fibers and suggested that these are favorable materials for making the composites. park et al. [21] observed an increase in the physical properties when 5% of the weight of the unsaturated polyester was used in the epoxy and unsaturated polyester blend. similarly harani et al. [22] have used unsaturated polyester for toughening the epoxy resin. the aim of the present work is to find the optimum weighted ratio of prepared blend in the weighted formula [polyester/(epoxy+pvf)] as (w/w) by using thermo-mechanical properties as well as to ascertain whether or not the three types of thermosetting-sack system can be effectively employed for making the composites. 2. experimental work 2.1. materials three different types of chemical adhesives: epoxy, polyvinyl formal (pvf) and unsaturated polyester with technical specifications shown in table 1 as well as synthetic sacks fibers that are used in the storage of sugar, rice and flour were applied as a reinforced composite material in this work. 2.2. methods 2.2.1. preparation of reinforced composite material sack fibers were first cleaned, washed thoroughly with tap water and left in the open air until dryness. the dried sack fibers of one layer were cut to the rectangular cross-section with a width of 15mm, a length of 170mm and a thickness of 0.5mm to be used for the bending and impact tests, and to the circular cross-section with diameter (30mm) and thickness 0.5mm to be used for the hardness and thermal conductivity tests. table 1, technical specifications of epoxy, pvf and unsaturated polyester resin epoxy resin polyvinyl formal (pvf) resin compressive strength: < 72 n/mm2 @7 days @20oc bs 6319 formaver 15/95e free flexural strength: < 60 n/mm2 @35oc bs 6319 flowing powder, bdh tensile strength: < 25 n/mm2 bs 6319 m.w. 24000 to 40000 pot life: 85 minutes @20oc pvf 82% specific gravity: 1.04 pvoh 5 to 6% viscosity: 1.0 poise @35oc pvac 9.5-13% min. application temperature: 5oc viscosity in 15% solution 60/40 toluene/ethanol at 25oc: 3000 to 4500cp unsaturated polyester resin appearance: transparence styrene wt%:32% viscosity at 25oc: 1000 cp specific gravity: 1.15 gelatinization time: 6 min. 2.2.2. preparation of the blend a) preparation of epoxy blend fixed weight of epoxy resin (17.5g) was added to a fixed quantity of hardener (5.8g) and agitated at constant mixing speed (500rpm) using a stirrer (labinco bv, model l-81, netherland), for a constant period of mixing time (15 minutes) at room temperature. b) preparation of pvf blend fixed weight of pvf resin (0.1g) in the form of solid phase (powder) was added to a fixed quantity of solvent (2.3g) and agitated for fully dissolving the pvf material at constant mixing speed and time (700rpm, 15 minutes) using the same stirrer at room temperature. c) preparation of unsaturated polyester blend different weights of unsaturated polyester varied from (5 to 25g) with its varied quantities of hardeness from (0.1 to 0.5g) and agitated at constant mixing speed and time (500rpm, 15 minutes) using the same stirrer at room temperature. d) preparation of (epoxy-pvf-unsaturated polyester) blend all blends of epoxy, pvf and unsaturated polyester were put together and agitated thoroughly at constant mixing speed and mixing time (500rpm and 5 minutes) respectively at room temperature and divided into two portions. these portions were directly put in moulds of tests and designated as untreated samples-without sack fibers (w.s.). treated samples of sack fibers for one and two layers are designated as (o.s.), (t.s.) respectively and were put in tests moulds and coated until saturated with the prepared blend. all prepared samples (untreated and treated) were left in the open air for one day at room temperature before conducting the laboratory tests. note that epoxy-pvf-unsaturated polyester blend is designated as a prepared blend in the weighted formula (polyester/(epoxy+pvf)) as (w/w) and it is at zero weight of polyester blend; i.e. (epoxy+pvf) blend is only designated as standard ratio (0w/w) of prepared blend in the experiments. 3. methodology experiments were performed to characterize the thermo-mechanical properties of the thermosetting polymeric composites. the untreated and treated samples of the prepared blend were loaded into the instruments so as to investigate the mechanical and thermal tests. the impact strength was determined using charpy impact instrument (time testing machine, xju-22, pendulum, time group, 2007, inc., usa). the bending deflection was determined by using phywe instrument (three point bending tester according to astm d790). while the hardness property was determined by using w lestor amsler, harkeprufer, din 53505, iso r868, shore d). on the other hand, the thermal conductivity test of prepared blend was achieved by using lee's disk instrument (kocyigit electronic, dc 0-30 volt, 6 amperes; uk). the thermal conductivity for the treated and untreated samples was calculated by using the following equations: e = p/ r[r(t1+t3) + 2(d1t1+0.5ds(t1+t2) + d2t2+ d3t3] k = e ds [t1 + 2t1 (d1 + 0.5ds)/r + t2ds/r] / (t2 – t1) where e = loss in heat per unit area in (w/cm2.oc) p = supplied power in (w) r = radius of disk in (cm) d1, d2, d3 = thickness of disks in (cm) ds = thickness of specimen in (cm) t1, t2, t3 = measured temperatures of disks no. 1, 2, and 3 in (oc) k = thermal conductivity in (w/cm.oc) 4. results and discussion 4.1. investigation of the optimum weighted ratio of prepared blend mechanical and thermal tests were carried out at different weighted ratios (0, 0.20, 0.40, 0.60, 0.79 and 0.99w/w) of prepared blend for untreated samples-without sack fibers (w.s.) to investigate the optimum weighted ratio of (epoxy-pvf-unsaturated polyester) blend. 4.1.1. mechanical tests a) hardness test the effect of untreated samples at different weighted ratios of prepared blend on the mechanical property, hardness in shore is shown in figure 1. it seems clearly that the values of hardness property of untreated samples increased from 66 to 95 shore with increasing the ratios of prepared blend from 0 to 0.40w/w and decreased to 78 shore at 0.99w/w. this behavior is due to the increase in the ratios of prepared blend from standard ratio (0w/w) to 0.40w/w which was associated with an increase in the concentration of unsaturated polyester blend that has been a good mechanical properties [6] to reach the strong chemical interaction and maximum bonding forces between two concentrations of matrix-binder (epoxy and pvf blends) and unsaturated polyester blend at 0.40w/w that represented the ability to absorb the applied energy [18]. similar observation was found by harani et al. [22] who used unsaturated polyester for toughening the epoxy resin. on the other hand, it can be clearly seen from figure 1 that the maximum hardness value of untreated sample occurred at 0.40w/w that is designated as the optimum weighted ratio for hardness test. fig.1. effect of untreated samples at different weighted ratios of prepared blend on the hardness property. b) impact strength test figure 2 shows the effect of untreated samples on the impact strength property in j/cm2 at different weighted ratios of prepared blend. it is clear to note that the maximum impact strength value of untreated sample occurred at the weighted ratio of prepared blend of 0.20w/w. this ratio showed a better chemical interaction and maximum bonding forces between the epoxide group of the matrix-binder and unsaturated polyester blend for the three thermosetting adhesives [2, 3]. on the other hand, the addition of unsaturated polyester to matrix blend led to increase the strength of matrix and overall impact properties of prepared blend [18].the weighted ratio at 0.20w/w is designated as the optimum weighted ratio for impact strength test. fig.2. effect of untreated samples at different weighted ratios of prepared blend on the impact strength property. fig.3. effect of untreated samples at different weighted ratios of prepared blend on the bending deflection property. c) bending deflection test the effect of untreated samples on the mechanical property, bending deflection in mm, at different weighted ratios of prepared blend is shown in figure 3. it seems clearly that the values of bending deflection property of untreated sample decreased from 19 to 4mm with increasing the ratios of prepared blend from standard ratio to 0.40w/w and increased to 6mm at 0.99w/w. it seems that the ratio of prepared blend at 0.40w/w showed a better resistance and lower bending distortion values. this can be related to the hydrogen bonding between three thermosetting polymeric adhesives of blends which promotes close packing at molecular level [19]. the results provided evidence that the prepared blend at 0.40w/w reached to the optimum weighted ratio for bending deflection test. d) thermal test figure 4 shows the effect of untreated samples at different weighed ratios of prepared blend on the thermal conductivity property in w/cm.oc. it seems clearly that the maximum value of the thermal conductivity of prepared blend occurred at the weighted ratio of 0w/w; i.e. the standard ratio of prepared blend. the minimum value of the thermal conductivity of prepared blend correspond to the weighted ratio of 0.20w/w. on the other hand, experimental results showed that the thermal conductivity of prepared blend at different weighted ratios is smaller than that of standard weighted ratio. this is due to thermal resistance of unsaturated polyester adhesive that led to increase the overall thermal resistance of the prepared blend [6]. the prepared blend at 0.20w/w is designated as the optimum weighted ratio for thermal conductivity test. fig.4. effect of untreated samples at different weighted ratios of prepared blend on the thermal conductivity property. 4.2. investigation of the reinforced composite material 4.2.1. mechanical tests a) hardness test table 2 shows the effect of untreated (w.s.) and treated samples with sack fibers (o.s., t.s.) on the hardness property at standard and optimum weighted ratios of prepared blend. at the standard weighted ratio, the percentage values of hardness for treated sample with sack fibers increased by 16 and 22% respectively compared to that of untreated sample. while at the optimum weighted ratio, they increased by 29 and 41% respectively. on the whole, it is observed that the treated sample with sack fibers at standard and optimum weighted ratios of prepared blend showed a better mechanical strength of the composite material and a better physical interaction with prepared blend. this result is in agreement with that reported by nielsen [11] who attributed that to the strong fiber-matrix interface bond for giving high mechanical properties. table 2, effect of untreated and treated sample on the hardness property at standard and optimum weighted ratios of prepared blend. weighted ratios of prepared blend (w/w) percentage increase of hardness in (shore) for treated samples o.s.% t.s.% standard (0) 16 22 optimum (0.20) 29 41 b) impact strength test table 3 shows the effect of untreated (w.s.) and treated samples with sack fibers (o.s., t.s.) on the impact strength property at the standard and optimum weighted ratios of prepared blend. table 3, effect of untreated and treated sample on the impact strength property at standard and optimum weighted ratios of prepared blend. weighted ratios of prepared blend (w/w) percentage increase of impact strength in (j/cm2) for treated samples o.s.% t.s.% standard (0) 9 13 optimum (0.40) 16 26 compared to untreated samples, the impact strength percentage values of treated samples with sack fibers for one layer (o.s.) and two layers (t.s.) increased by 9 and 13% respectively for standard ratio. whilst, they increased by 16 and 26% respectively for the optimum weighted ratio. treated samples of sack fibers with two layers (t.s.) showed better fiber reinforced composites as observed from table 3. this can be attributed to the strong physical interaction between the prepared blend of thermosetting and reinforced composite fibers that led to increase in the strength and toughness between them [14]. the sack fibers with two layers (t.s.) effect on the impact strength property was predominant. mechanical properties of a fiber-reinforced composite depend on many parameters, such as fiber strength, modulus, fiber length and orientation, in addition to the fiber-matrix interfacial bond strength [11]. c) bending deflection test table 4 shows the effect of untreated (w.s.) and treated samples with sack fibers (o.s., t.s.) at standard and optimum weighted ratio of prepared blend on the bending deflection in mm. the percentage values of bending deflection for treated sample with sack at standard weighted ratio were improved by 16 and 25% respectively compared to that of untreated sample. while at the optimum ratio, they improved by 29 and 41% respectively. on the other hand, the treated sample with sack fibers led to enhance the bending deflection property of the treated sample for both standard and optimum weighted ratios. this is due to the excellent mechanical strength of the prepared blend and reinforced composite material. these findings are in agreement with those reported by karnani et al [11] who showed that the mechanical properties of a natural fiber-reinforced composite depend on the fiber-matrix interfacial bond strength. a strong fiber-matrix interface bond is critical for high mechanical properties of composites. rajulu et al. [16] found that the blend (epoxy and polyester) coated fibers (bamboo) had higher mechanical properties. they attributed that to the hydrogen bonding between the unsaturated polyester and epoxies group. table 4, effect of untreated and treated sample on the bending defection at standard and optimum weighted ratios of prepared blend. weighted ratios of prepared blend (w/w) percentage increase of bending deflection (mm) for treated samples o.s.% t.s.% standard (0) 16 25 optimum (0.20) 29 41 d) thermal test the effect of untreated and treated samples with sack fibers on the thermal conductivity property in w/cm.oc at standard and optimum weighted ratios of prepared blend is shown in table 5. it is clear to note that the thermal conductivity of treated samples with sack fibers have lower percentage values and improved by 8 and 12% respectively when compared to those of the untreated samples. whilst at the optimum weighted ratio, they improved by 13 and 19% respectively compared to that of the untreated sample. it is generally observed that the improvement of thermal conductivity property for treated sample with two layers of sack fibers was predominant due to the best thermal resistance of them. this depends on processing conditions/ techniques that has significant influence on the mechanical properties of fiber reinforced composites [12, 13]. table 5, effect of untreated and treated sample on the thermal conductivity at standard and optimum weighted ratios of prepared blend. weighted ratios of prepared blend (w/w) percentage increase of thermal conductivity (w/cm.oc) for treated samples o.s.% t.s.% standard (0) 8 12 optimum (0.40) 13 19 5. conclusions from the results presented, it can be concluded that: 1. the optimum mixing speed for the preparation of epoxy, unsaturated polyester and prepared blends was 500rpm while for pvf blend was 700rpm. the optimum mixing time for all blends was 15 minutes; except for prepared blend, it was 5 minutes. 2. the optimum weighted ratio of prepared blend for hardness and bending deflection properties was 0.40w/w. while for impact strength and thermal conductivity properties was 0.20w/w. 3. the maximum hardness and impact strength values of untreated samples occurred at the optimum weighted ratio of prepared blend were found to be 95 shore and 2.25 j/cm2 respectively. 4. the minimum bending deflection and thermal conductivity values of untreated samples occurred at the optimum weighted ratio of prepared blend were found to be 4mm and 0.01094 w/cm.oc respectively. 5. experimental results showed that treated samples with sack fibers led to enhance and improve in the mechanical and thermal properties when compared to the untreated sample. 6. the mechanical and thermal properties of composite were significantly influenced by the techniques used. the improvement of treated samples with two layers (t.s.) of sack fibers for both mechanical and thermal properties is predominant. 7. sack fibers can be used as an important source of fiber for composites and other industrial applications. 8. the above observations clearly indicate that the prepared blend of thermosetting (epoxy-pvf-unsaturated polyester) blend and solid wastes-sack fibers may be recommended as favorable materials for making the composites of three types of thermosetting-synthetic sacks system to satisfy both economical and ecological interests. 6. references [1] hull, d. and clyne, t.w. (1996). an introduction to composite materials. cambridge university press, cambridge. [2] d.h. mueller, a. krobjilowski, (2003), “new discovery in the properties of composites reinforced with natural fibers”, journal of industrial textiles, 33(2), 111-129. [3] h. lilholt, j.m. lawther, (2000), “comprehensive composite materials”, chapter 1.10, elsevier ltd. [4] sinha, r., (2000). outlines of polymer technology.prentice-hall by india private ltd. new delhi –10001. [5] a.k. bledzki, o. faruk, (2003), “wood fibre reinforced polypropylene composites: effect of fibre geometry and ccoupling agent on physico-mechanical properties”, applied composite materials, 10(6), 365-379. [6] sharifah, h.a., martin, p.a., simon, t.c. and simon, r.p. (2005). modified polyester resins for natural fiber composites. compos. sci. technol.65:525-535. [7] pal, s., mukhophadhyay, d., sanyal s. and mukherjea, r. (1988). studies on process variables for natural fiber composites--effect of peap as interfacial agent. j. appl. polym. sci. 35: 973-985. [8] owolabi, o., czvikovszky, t. and kovacs, i. (1985). coconut fiber reinforced thermosetting plastics. j. appl. polym. sci. 30:1827-1836. [9] white, n. and ansell, m., (1983). straw-reinforced polyester composites. j. mater. sci. 18:1549-1556. [10] mwaikambo, l. and bisanda, e. (1999). the performance of cotton/kapok fabric-polyester composites. polym. testing 18:181-198. [11] karnani, r., m. krishnan and r. narayan. (1997). biofiber-reinforced polypropylene composites. polymer engineering and science 37 (2): 476-483. [12] wang, b. thesis (2004). pre-treatment of flax fibers for use in rotationally molded biocomposites. university of saskatchewan, saskatoon. [13] george, j., m.s. sreekala and s. thomas. (2001). a review on interface modification and characterization of natural fiber reinforced plastic composites. polymer engineering and science 41 (9):1471-1485. [14] kau, h.t. (1990). a study of the impact behavior of chopped fiber reinforced composite. polymer composites 11 (5):253-264. [15] jang, b. z., l.c. chen, l.r. hwang, j.e. hawkes and r.h. zee. (1990). the response of fibrous composites to impact loading. polymer composites 11 (3):144-157. [16] reed, p.e. and l. bevan. (1993). impact damage in a composite material. polymer composites 14 (4):286-291. [17] nielsen, l.e. (1974). mechanical properties of polymers and composites. vol. 2. new york, ny: marcel dekker, inc. [18] shah, v. (1998). handbook of plastics testing technology. 2nd ed. new york, ny: john wiley and sons. [19] a. varada ragulu, l. ganga devi, g. babu rao and lakshminaryana reddy. (2003). journal of reinforced plastics and composites, vol. 22, no. 11/2003. [20] varada ragulu, a., babu rao, g., lakshminaryana reddy. r. and sanjeevi (2001). journal of reinforced plastics and composites, 20: 335. [21] park, s.j., w.b. and lee, j.r. (1999). polymer j., 31: 28. [22] harani, h., fellahi, s. and barkar, m. (1999). j. appl.polym. sci., 71: 29. الأكياس النسيجية كألياف تقوية مركبة مع اللواصق المتصلدة مخلد عامر حسين* فلك أسامة عباس** رغد أسامة عباس*** *, ** مركز بحوث البيئة /الجامعة التكنولوجية * البريد الالكتروني: mukheled@yahoo.com *** قسم هندسة المواد /الجامعة التكنولوجية الخلاصة نُفذت هذه الدراسة للتحري عن تحضير مزيج يتكون من ثلاثة لواصق بوليمرية متصلدة وهي (الايبوكسي والبولي فينيل فورمال والبولي استر غير المشبع). تم اُستخدام كل من لاصقي (الايبوكسي والبولي فينيل فورمال) كرابط عند أوزان ثابتة، بينما اُستخدم لاصق البولي استر غير المشبع عند أوزان مختلفة وأضيف إلى الرابط لإنتاج المزيج المحضر (الايبوكسي والبولي فينيل فورمال والبولي استر غير المشبع). نُفذت مجموعة من التجارب عند ظروف تشغيلية مختلفة (سرعة الخلط وزمن الخلط) عند درجة حرارة الغرفة لتحديد أفضل الظروف التشغيلية. وقد وجدت أفضل سرعة وزمن خلط للمزيج المحضر عند 500rpm) و5 دقائق) على التوالي. تم استخدام النفايات الصلبة (ألياف ألأكياس النسيجية) المتواجدة بكميات وفيرة وقليلة الكلفة ومصدر متجدد للألياف كصديق للبيئة وبديل لألياف التدعيم في المواد المتراكبة. أجريت العديد من الاختبارات الميكانيكية والحرارية للمزيج المحضر عند نسب وزنيه مختلفة. حُددت أفضل نسبة وزنيه للمزيج المحضر عن طريق خواص (الصلادة وتشويه الانحناء) للنماذج غير المعاملة، وقد وُجدت w/w)0.40). بينما وُجدت لخواص (قوة الصدمة والموصلية الحرارية) عند (0.20w/w). عند هذه النسب الوزنيه المثالية للنماذج غير المعاملة، وجدت أعلى قيم لخواص (الصلادة وقوة الصدمة) للمزيج المحضر عند (95shore و(2.25j/cm2 على التوالي. بينما وجدت اقل قيم لخواص (تشويه الانحناء والموصلية الحرارية) عند (4mm و w/cm.oc0.01094( على التوالي. أظهرت هذه الخواص أفضل قوى ترابط وتجاذب فيزيائي بين لاصقي الرابط (الايبوكسي والبولي فينيل فورمال) والبولي استر غير المشبع. أظهرت النتائج العملية للنماذج المعاملة بألياف ألأكياس النسيجية عند نسبها الوزنيه المثالية أفضل قوى ترابط بين اللواصق والألياف والتي أدت إلى تعزيز وتحسين الخواص الميكانيكية (الصلادة وقوة الصدمة وتشويه الانحناء) والحرارية (الموصلية الحرارية) مقارنة مع النماذج غير المعاملة. هذه التحسينات التي طرأت على النماذج المعالجة باستخدام طبقتين من ألياف ألأكياس النسيجية كانت هي السائدة. � embed pbrush ��� page 56 _1289026969.unknown _1173207870 <4d6963726f736f667420576f7264202d2031312d3231d4dfd1ed20e6c7cde3cf20e6e1ccede420e6c7cbedd1> al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 16, no. 1, march, (2020) p. p. 1121 optimization the effect of electrode material change on edm process performance using taguchi method shukry h. aghdeab* ahmed ghazi abdulameer ** lujain hussein kashkool *** atheer rasim mohammed **** *,**,***,**** department of production and metallurgy engineering/ university of technology/ baghdad/ iraq * email: shukry_hammed@yahoo.com ** email: ahmed.taku@yahoo.com *** email: lujain.1182@gmail.com **** email: atheermtc86@gmail.com (received 20 january 2019; accepted 4 september 2019) https://doi.org/10.22153/kej.2020.09.001 abstract electrical discharge machining (edm) is a widespread nontraditional machining (ntm) processes for manufacturing of a complicated geometry or very hard metals parts that are difficult to machine by traditional machining operations. electrical discharge machining is a material removal (mr) process characterized by using electrical discharge erosion. this paper discusses the optimal parameters of edm on high-speed steel (hss) aisi m2 as a workpiece using copper and brass as an electrode. the input parameters used for experimental work are current (10, 24 and 42 a), pulse on time (100, 150 and 200 µs), and pulse off time (4, 12 and 25 µs) that have effect on the material removal rate (mrr), electrode wear rate (ewr) and wear ratio (wr). a minitab software environment was used to adopt taguchi method to analyze the effect of input on output parameters of edm. the results of the present work showed that the best of mrr in copper and brass electrodes with (current 42 a, pulse on time 100 µs and pulse off time 25 µs) are (84.355×10-3 g/min) and (43.243×10-3 g/min) respectively, and the mrr predicted by taguchi are (86.1751×10-3 g/min) in copper electrode by using the parameters with (current 10 a, pulse on time 200 µs and pulse off time 25 µs) and (43.2979×10-3 g/min) in brass electrode at current 42 a, pulse on time 100 µs, and pulse off time 25 µs. the lowest ewr occurs with a value of (1.4510×10-3 g/min) with (current 10 a, pulse on time 100 µs, pulse off time 4 µs) variables when using a copper electrode. the highest wr (2.602508) was found for the brass electrode with (current 24 a, pulse on time 200 µs, pulse off time 4 µs) variables. keywords: edm, taguchi method, material removal rate, electrode wear rate, wear ratio. 1. introduction one of the non-conventional material removal processes is an electrical discharge machining (edm), which is widely used in industry [1]. metals are taken away from the piece by a series of frequent periodic electric spark between electrode and workpiece separate by a liquid solution [2]. at present, edm is the most widely used technique for high – precision machining of all types of conductive metals, alloy irrespective of hardness. it is also used in automobile industry, aerospace and in farm industry [3]. an initial cost of edm machining is high but with a selection of optimal parameter's levels, its wastage, operating cost decreases with quality improvements [4]. in tested the influence of the electrical discharge machining parameters like, pulse on time (ton), pulse off time (toff), and current (i) on material removal rate (mrr) for stainless steel, the results were resolved by using variance analysis and mohannad r. ghanim al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 1121 (2020) 12 response graphs, it has been different collections of edm process parameters are obtain higher mrr and better surface roughness (ra) [5]. srivastava & pandey [6] conducted an experiment with the process parameters like a pulse on time, current, duty cycle and voltage on response factors like tool wear rate, material removal rate and surface roughness with the cryogenically treated electrode. they revealed that current, pulse on time and duty cycle have a significant effect on tool wear and material removal rate. shukry et al. [7] studied the effect of edm parameters such as current, pulsation on time and pulsation off time on surface roughness of steel 304 with dielectric solution of gas oil by supplied dc current values (10, 20, and 30a). the voltage of (140v) uses to cut 1.7mm thickness of the steel and use the copper electrode. they found that the parameters of current and pulsation on time affected the surface roughness (ra) directly. discharge current was the most effective parameter on the mrr & ra when using the copper material as voltage, current, pon and poff for responses of surface roughness and material removal rate on the edm of tool steel (aisi d2) [8]. selection of input parameter played a great property of edm on nickel superalloy material (rene80) with aluminum (al) as an electrode. that the input parameters considered are i; pon and poff are used for experimental work and their effect on mrr, tool wear rate, and ra [9]. 2. objectives although various parameters could be considered for electrical discharge machining process, but in the present work, three process parameters namely discharge current, pulse-ontime, and pulse-off time are considered. to find out the optimal factors of maximization for mrr in edm process, taguchi technique is used. the works have been done with oil as dielectric solution on (cm 323c edm machine), as shown in fig. 1. high-speed steel aisi m2 size 60×45×3mm plate is chosen for conductive experiment with nine specimens. the chemical, mechanical, and physical properties of the highspeed steel are given in table 1, and table 2, respectively. fig. 1. edm cm323c cnc machine. table 1, chemical composition of aisim2 works material. material weigh t (%) material weight (%) c 0.855 mo 5.83 si 0.305 ni 0.14 mn 0.28 cu 0.175 p 0.001 v 1.88 s 0.001 w 5.73 cr sn 4.71 0.001 co fe 0.045 balance table 2, mechanical and physical properties of high speed steel. properties aisi m2 (%) modulus of elasticity (gpa) 207 specific heat capacity (j/g°c) 0.46 thermal conductivity (w/mk ) 19 electrical resistivity (ohmcm) 54x10-6 density (g/cm3) 8.14 hardness (hrc) chirpy impact (j) poisson's ratio 61-66 31.2-38 0.30 the tool electrodes’ material that are used in the experimental work are copper and brass electrodes (ϕ4×100 mm) with negative polarity, as shown in fig. 2 (acopper electrode and b brass electrode). mohannad r. ghanim al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 1121 (2020) 13 fig. 2. the high-speed steel (hss) aisi m2 as a workpieces and electrodes (a) copper electrode, (b) brass electrode. by using three sets of experiments (peak current (ip), pulse on time (ton), gap voltage (vg)) to find tool wear rate, experiments showed that the optimization of process parameters, the third set gave the maximum tool wear rate when using the copper as a tool material and the aim was to optimize set of process parameters [10]. variables on the material removal rate (mrr) in die-sinking edm of en19 material for four processes (pulse on time, pulse off time, discharge current and gap voltage) with electrolytic copper use as the electrode material. the different combinations of process parameters and by analysis of variance (anova) found that pulse off time, discharge current, gap voltage and the interaction terms are significant whereas the pulse on time has almost negligible effect on mrr 1.45% is the error between the predicted and experimental mrr value was found to be very effective as shown in this studied [11]. this work studies the optimization of edm process parameters on machining per for using high-speed steel aisi m2 as a workpiece and copper and brass as an electrode. the material removal rate of the process obtained by the formula [12]: …(1) mrr= material removal rate in (g/min). mt = machining time in (min). wbm= weight workpiece before machining in (g). wam= weight after workpiece machining in (g). the electrode wear rate of the process obtained by the formula [12]: …(2) where: ewr= electrode wear rate in (g/min). mt = machining time in (min). ebm= weight electrode before machining in (g). eam= weight electrode after machining in (g). the wear ratio of the process obtained by used the formula [13]: …(3) where: wr= wear ratio. ewr= electrode wear rate in (g/min). mrr= material removal rate in (g/min). 3. taguchi method to find out the best machining parameters of maximization for mrr in edm process, taguchi analysis is used. this method can identify the main effective parameters with embedded sublevel parameters. this method is used to loss function parameters diverge from the required values into a signal to noise (s/n) ratio to three types mainly as follows: (1) larger-the-better (2) nominal-the-better (3) smaller-the-better the characteristic of higher value represents better machining performance. for example, material removal rate is termed as larger-thebetter. characteristics of lower value appear for best machining interpretation. hence it is concluded that for material removal rate "largeris –better" were selected for finding optimum machining parameters. the overcut of (s/n) ratio is calculated by [14]: …(4) where the yi is ith observed value of the response and n: number of observations. the design and levels parameters of the study mohannad r. ghanim al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 1121 (2020) 14 experiments at different factors of consideration (current, pulse on time and pulse on time) are shown in table 3. minitab 17 software is used for the design of the experiment in taguchi analysis. a number from ordinary orthogonal array has been created to ease of experimental designing. table 4 shows the taguchi matrix method of the experiment at a different number of experiments with machining parameters grades. table 3, design of experiments. factors of code consideration grade 1 2 3 current(a) i 10 24 42 pulse on time(µs) ton 100 150 200 pulse off time(µs) toff 4 12 25 table 4, taguchi matrix ((3-grades design)). no. of experiments machining parameters grades i ton toff current(a) pulse on pulse off time(µs) time(µs) 1 2 3 4 5 6 7 8 9 1 1 1 2 2 2 3 3 3 1 2 3 1 2 3 1 2 3 1 2 3 2 3 1 3 1 2 4. results and discussion the obtained experimental results are shown in the tables (5-13), respectively. mrr, ewr and wr were analyzed in accordance with the input parameters i.e. current, ton and toff. nine experiments were conducted according to the tables (5-7) and the average of the three was taken for the analysis purpose. in order to investigate the effect of three parameters i.e. i. ton and toff on the mrr, ewr and wr experiments were conducted using l9 orthogonal array along with the s/n ratio by used taguchi design method of experiment at a different number of experiments with machining parameters grades. according to taguchi method of the experiment, the better quality characteristics for material removal rate, electrode wear rate and wear ratio by use copper and brass electrodes. the ideal conditions for mrr required is current 42 a, ton 100 µs and toff 25 µs of copper electrode. the required ewr is current 10 a, ton 100 µs and toff 4 µs of copper electrode, and the required wr is current 10 a, ton 100 µs and toff 4 µs of copper electrode. the optimal process parameters combination for max. mrr is found to be current at the highest level, pulse on time at the lowest level, and pulse off time at the highest level of the copper electrode, max. ewr is found to be current at the highest level, pulse on time at the lowest level, and pulse off time at the highest level of the brass electrode, and max. wr is found to be current at a moderate level, pulse on time at the highest level, and pulse off time at lowest level of brass electrode. figs. (3-4) show the main effect of machining variables (i, ton and toff) on the mrr of copper electrode in rang (27.391-84.355×10-3 g/min) with current (10-42 a), pulse on time (100-200 µs), and pulse off time (4-25 µs) and obtained high mrr (84.355×10-3 g/min) with current (42 a), ton (100 µs), and toff (25 µs) and the mrr of brass electrode in rang (18.034-43.243×10-3 g/min) with current (10-42 a), ton (100-200 µs), and toff (4-25 µs). high mrr of (43.243×10-3 g/min) was obtained with current (42 a), ton (100 µs), and toff (25 µs). figs. (5-6) show the main effect of machining variables (i, ton and toff) on the ewr of copper electrode in rang (1.451-25.0716×10-3 g/min) with current (10-42 a), pulse on time (100-200 µs), and pulse off time (4-25 µs) and obtained low ewr (1.451×10-3 g/min) with current (10 a), ton (100 µs), and toff (4 µs) and the ewr of brass electrode in rang (25.8523-91.4651×10-3 g/min) with current (10-42 a), ton (100-200 µs), and toff (4-25 µs).low ewr of (25.8523×10-3 g/min) was obtained with current (10 a), ton (150 µs), and toff (12 µs). figs. (7-8) show the main effect of machining variables (i, ton and toff) on the wr of copper electrode in rang (0.026619-0.297215) with current (10-42 a), pulse on time (100-200 µs), and pulse off time (4-25 µs). high wr of (0.297215) was obtained with current (42 a), ton (100 µs), and toff (25 µs) and the wr of brass electrode in rang (1.38796-2.60258) with current (10-42 a), ton (100-200 µs), and toff (4-25 µs) and obtained high wr (2.60258) with current (24 a), ton (200 µs), and toff (4 µs). the response tables for mrr, ewr and wr are given in tables (8-13). it is verified from table 8 that toff has the maximum effect as compared to the i and ton of the copper electrode. the ranks on the process parameters clarify this. delta values are the difference between the maximum and minimum values from mohannad r. ghanim al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 1121 (2020) 15 level 1 to level 3. as mrr is the higher, the better type performance characteristics, so table 8 gives the optimal setting of process parameters. from table 8 and fig. 3, it has been envisaged that (i) 2 (ton) 3 (toff) 1 gives the maximum mrr of copper electrode. same condition as the rest of the tables (913). from table 9 and fig. 5 it has been envisaged that (i) 2 (ton) 3 (toff) 1 gives the maximum mrr of copper electrode. figs. (9-14) shows the main effect curve of mrr on current and pulse on at copper and brass electrodes. it has been noted from 3d figures influence that whenever current and pulse on-time increases the material removal rate increases. the mrr, ewr and wr increase with the increase in i and ton. the reason exists behind this was the high value of spark-energy. as ton is the time for which the current pulse in a circuit remains active. a large value of ton depicts the large current value and this current value is the reason for spark. so, a high ton value correspondingly enhances the spark energy. this spark energy removes the material from the work-piece. high ton value removes a large amount of material as compared to the low ton value. the values of mrr, ewr and wr found to be decreased with the increases in toff value. this was due to the low value of spark-energy in the circuit. as toff is the time gap between two successive pulses in a circuit, so if the time gap between two successive pulses decreased, then the value of current within a specified time period also decreases. this would reduce the intensity of the spark in the circuit. table 5, result machining variables experimental of mrr with taguchi design. table 6, result machining variables experimental of ewr with taguchi design. no. of experiments i ton toff mrr current (µs) (µs) 103 (a) (g/min.) (copper) pmea n2 mrr 10-3(g/min.) (brass) pmean3 1 10 100 4 54.510 58.2514 18.982 18.8696 2 10 150 12 70.072 63.8051 18.034 18.0889 3 4 5 6 7 8 9 10 24 24 24 42 42 42 200 100 150 200 100 150 200 25 83.652 12 48.840 25 68.876 4 31.833 25 84.355 4 27.391 12 32.849 86.1751 51.3654 72.6174 25.5661 78.0881 29.9164 36.5904 22.252 30.030 30.157 18.129 43.243 27.116 30.769 22.3096 30.0876 30.0446 18.1839 43.2979 27.1736 30.6566 no. of experiments i ton toff ewr current (µs) (µs) 10-3 (a) (g/min.) pmean2 ewr 10-3(g/min.) (brass) pmean3 1 10 100 4 1.4510 1.4311 32.7528 32.6525 2 10 150 12 3.8702 3.8708 28.8523 28.8513 3 4 5 6 7 8 9 10 24 24 24 42 42 42 200 100 150 200 100 150 200 25 3.9706 12 13.4573 25 10.9633 4 1.4791 25 25.0716 4 7.074 12 5.9832 3.9706 13.4673 10.9333 1.4721 25.2716 7.0584 5.7822 30.8768 58.9802 59.5285 48.4499 91.4651 66.8264 71.7554 30.8771 58.9502 59.5235 48.4139 91.4651 66.7263 71.7253 mohannad r. ghanim al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 1121 (2020) 16 table 7, result machining variables experimental of wr with taguchi design. fig. 3. main effects plot of the mean value for mrr of the copper electrode. fig. 4. main effects plot of the mean value for mrr of the brass electrode. fig. 5. main effects plot of the mean value for ewr of the copper electrode. fig. 6. main effects plot of the mean value for ewr of the brass electrode. no. of experiments i ton toff wr current (a) (µs) (µs) (copper) pmean2 wr (brass) pmean3 1 10 100 4 0.026619 0.026531 1.725466 1.72547 2 10 150 12 0.055232 0.056252 1.599883 1.59988 3 4 5 6 7 8 9 10 24 24 24 42 42 42 200 100 150 200 100 150 200 25 0.047465 12 0.275538 25 0.159174 4 0.046464 25 0.297215 4 0.258238 12 0.182142 0.049462 0.275732 0.158175 0.048465 0.299213 0.254233 0.186143 1.387596 1.464042 1.973953 2.602508 2.115143 2.464463 2.332068 1.38760 1.46404 1.97395 2.60251 2.11514 2.46446 2.33207 mohannad r. ghanim al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 1121 (2020) 17 fig. 7. main effects plot of mean value for wr of copper electrode. fig. 8. main effects plot of the mean value for wr of the brass electrode. table 8, response table for means of the copper electrode (mrr). level i (a) ton (µs) toff (µs) 1 69.41 62.57 37.91 2 49.85 55.45 50.59 3 48.20 49.44 78.96 delta 21.21 13.12 41.05 rank 2 3 1 table 9, response table for means of brass electrode (mrr). level i (a) ton (µs) toff (µs) 1 19.76 30.75 21.41 2 26.11 25.10 26.28 3 33.71 23.72 31.88 delta 13.95 7.03 10.47 rank 1 3 2 table 10, response table for means of copper electrode (ewr). level i (a) ton (µs) toff (µs) 1 3.097 13.327 3.335 2 8.633 7.302 7.770 3 12.710 3.811 13.335 delta 9.612 9.516 10.000 rank 2 3 1 table 11, response table for means of brass electrode (ewr). level i (a) ton (µs) toff (µs) 1 30.83 61.07 30.83 2 55.65 51.74 53.20 3 76.68 50.36 60.62 delta 45.86 10.71 11.28 rank 1 3 2 table 12, response table for means of copper electrode (wr). level i (a) ton (µs) toff (µs) 1 0.04311 0.19979 0.11044 2 0.16039 0.15755 0.17097 3 0.24587 0.09202 0.16795 delta 0.20276 0.10777 0.06053 rank 1 2 3 table 13, response table for means of brass electrode (wr). level i (a) ton (µs) toff (µs) 1 1.571 1.768 2.264 2 2.014 2.013 1.799 3 2.304 2.107 1.826 delta 0.733 0.339 0.465 rank 1 3 2 fig. 9. show main effect curve of mrr on current and pulse on of copper electrode. mohannad r. ghanim al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 1121 (2020) 18 fig. 10. show main effect curve of mrr on current and pulse on of brass electrode. fig. 11. show main effect curve of ewr on current and pulse on of copper electrode. fig. 12. show main effect curve of ewr on current and pulse on of brass electrode. fig. 13. show main effect curve of wr on current and pulse on of copper electrode. fig. 14. show main effect curve of wr on current and pulse on of brass electrode. 5. conclusions in this investigation, experiments on electrical discharge machining were conducted to examine the influence of machining output possessed for idea are mrr, ewr and wr of the high speed steel aisi m2 workpiece using copper and brass electrodes tool by taguchi design method. improvement of mrr, ewr and wr have been also investigated. the experiment depends on various parameters namely (i), (ton), and (toff) which has been selected. this experiment is based on l9 orthogonal array by taguchi design, was conducted and minitab 17 software was used for this experiment. the major conclusions of this work are as follows: mohannad r. ghanim al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 1121 (2020) 19 1current has most significant parameters on mrr, ewr and wr but ton moderately affects the mrr, ewr and wr while toff has the least significant influence on mrr, ewr and wr for two electrodes copper and brass. 2the best operation parameters, as shown in the observation table, are current 42 a, ton 100 µs, and toff 25 µs, for both copper and brass electrodes. 3through practical experiments, it has been noted that the use of a copper electrode is better than the electrode of the brass in terms of the mrr, ewr, and wr. notation edm electrical discharge machining ewr electrode wear rate hss high speed steel i current ip peak current mr material removal mrr material removal rate mt machining time n number of observations ntm nontraditional machining poff pulse off time pon pulse on time ra surface roughness s/n signal to noise ratio toff pulse off time ton pulse on time vg gap voltage wr wear ratio wam weight after machining wbm weight before machining yi ith observed value of the response 6. references [1] k. ojha, r. k. garg, k. k. singh, "mrr improvement in sinking electrical discharge machining: a review," journal of minerals & materials characterization & engineering, vol. 9, no. 8, p. 709-739, 2010. 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[13] a. a. khan, m. y. ali and m. m. haque, “a study of electrode shape configuration on the performance of die sinking edm” international journal of mechanical and materials engineering (ijmme), vol. 4, no. 1, p.19 -23, 2009. [14] s. k. ghazi, s. h. aghdeab and m. a. abdullah “investigation and prediction of mrr in ecm process using taguchi method” association of arab universities journal of engineering sciences, vol. 24, no. 3, p.190 -197, 2017. )2020( 1121، صفحة 1العدد ، 16دجلة الخوارزمي الهندسية المجلمشكري حميد غضيب 21 (edm)امثيلية تاثير تغير مادة القطب على اداء عملية التشغيل بالشرارة الكهربائية باستخدام طريقة تاكوشي **احمد غازي عبداالمير *شكري حميد غضيب ****أثير راسم محمد ***لجين حسين كشكول الجامعة التكنولوجية /قسم هندسة االنتاج والمعادن *******،،**،* shukry_hammed@yahoo.com: البريد االلكتروني* ahmed.taku@yahoo.com: البريد االلكتروني** lujain.1182@gmail.com: البريد االلكتروني*** atheermtc86@gmail.com: البريد االلكتروني**** الخالصة لتصنيع هندسة معقدة أو أجزاء معدنية صلبة للغاية يصعب ntm) عمليات تصنيع غير تقليدية واسعة النطاق ( (edm)تعتبر عملية التفريغ الكهربائي تتميز باستخدام تآكل التفريغ الكهربائي. تناقش هذه (mr)تشغيلها بواسطة عمليات التشغيل التقليدية. آلتشغيل بالتفريغ الكهربائي هي عملية إلزالة المواد باعتبارها القطعة المشغلة واستخدم النحاس والبراص كأقطاب. محددات m2عالي السرعة aisi (hss)على الصلب edmت المثلى لالورقة المحددا ١٢و ٤)مايكروثانية ووقت نبضة التوقف ( ٢٠٠و ١٥٠، ١٠٠) ، وقت نبضة التشغيل (a ٤٢ (24,10, اإلدخال المستخدمة في العمل التجريبي الحالية ). استخدام برنامج ميني تاب باعتماد wr) ونسبة البلى (ewr)، معدل بلى االقطاب ( (mrrيكروثانية والتي تؤثر على معدل إزالة المواد) ما ٢٥و . أظهرت نتائج هذا العمل أن أفضل معدل إزالة المواد في أقطاب النحاس edmطريقة تاكوشي لتحليل تأثير المدخالت على مخرجات المحددات من ال × ٤٣٫٢٤٣غرام/دقيقة) و (٣-١٠× 84.355 (مايكرو ثانية) ٢٥مايكرو ثانية ووقت نبضة التوقف ١٠٠، وقت نبضة التشغيل a ٤٢راص مع (لتيار والب لمتغيرات غرام/دقيقة) في القطب النحاسي باستخدام ا ٣-١٠× ٨٦٫١٧٥١غرام/دقيقة) على التوالي ، ومعدل إزالة المواد التي تنبأت عن تاكوشي هي ( ٣-١٠ غرام/دقيقة) في القطب النحاسي في ٣-١٠× ٤٣٫٢٩٧٩مايكرو ثانية ) و ( ٢٥مايكرو ثانية ووقت نبضة التوقف ٢٠٠، وقت نبضة التشغيل a ١٠(التيار غرام ٣-١٠×١٫٤٥١٠يمة (مايكرو ثانية. يحدث أدنى معدل بلى االقطاب بق ٢٥مايكرو ثانية ، ووقت نبضة التوقف ١٠٠، وقت نبضة التشغيل a ٤٢التيار مايكرو ثانية) عند استخدام القطب النحاس. تم العثور على ٤مايكرو ثانية ، ووقت نبضة التوقف ١٠٠، نبضة التشغيل a ١٠دقيقة) مع متغيرات (التيار / مايكرو ثانية). ٤رو ثانية ، ووقت نبضة التوقف مايك ٢٠٠، نبضة التشغيل a ٢٤لإللكترود النحاسي مع المتغيرات (التيار 2.602508)نسبة البلى ( أعلى al-khwarizmi!! engineering!!! journal al-khwarizmi engineering journal, vol. 6, no. 1, pp 57-68 (2010) microstructure and some properties of aluminum-silicon matrix composites reinforced by alumina or chromia ahmed a. moosa department of production engineering and metallurgy/ university of technology (received 13 july 2009: accepted 6 september 2009) abstract in this work, yttrium oxide particles (powder) reinforced al-si matrix composites (y2o3/al-si) and chromium oxide particles reinforced al-si matrix composites (cr2o3/al-si) were prepared by direct squeeze casting. the volume percentages of yttrium oxide used are (4, 8.1, 12.1, 16.1 vol %) and the volume percentages of the chromium oxide particles used are (3.1, 6.3, 9.4, 12.5 vol. %). the parameters affecting the preparation of y2o3/al-si and cr2o3/al-si composites by direct squeeze casting process were studied. the molten al-si alloy with yttrium oxide particles or with chromium oxide particles was stirred again using an electrical stirrer at speed 500 rpm and the molten alloy was poured into the squeeze die cavity. the pouring temperature that used for all castings is (700)˚c. the required squeeze pressure, 53 mpa, was then applied for 30 seconds at a delay time of 5. the die temp is (200˚c). the y2o3/al-si composites and cr2o3/al-si composites produced by squeeze casting have more microstructure refinement, higher hardness and lower wear rate than the unreinforced alloy. keywords: composite, microstructure, al-si , yttria , alumina 1. introduction the squeeze casting technique produces parts with reduced porosity levels because of the high pressure applied during solidification and due to efficient liquid feeding obtained by moving the ram to compensate for the freezing contraction. the cooling rate of the casting can be increased by applying high pressure during solidification due to increase in thermal conductivity [1, 2]. metal matrix composites (mmcs) of metallic alloys reinforced with ceramics particles are designed to offer high specific mechanical properties that are highly desirable in various applications and provide a relatively novel way of strengthening metals [3,4]. aluminum/silicon alloys are known for their high strength to weight ratio, good castability, low thermal expansion and high corrosion resistance. these properties have led to their application in all types of internal combustion engines as pistons, cylinder blocks and cylinder heads. al-si matrix composites are composed of al-si alloy matrix, and reinforcement. reinforcements added to al-alloy matrices include intermetallic compounds, ceramic phases such as oxides, carbides and nitrides as well as refractory metals[5]. particle reinforced composites are characterized by particles having a diameter greater than 1 µm with a volume fraction of 5 to 40%. particle reinforced composites show isotropic stiffness improvements with generally lesser degradation of fracture properties than that of whisker reinforced mmcs [1]. etter et al. [6] also examined graphite particles with al-si alloy prepared by squeeze casting, but with different si content. they concluded an increase in the mechanical strength and fracture toughness by using this process and with si addition. long et al. [7] showed an increase in the mechanical properties (stiffness, hardness, and fatigue strength and wear resistance) before and after heat treatment of 60wt٪ sic particles /alcu-mg-ag alloy. this was related directly to the addition of sic particles and squeeze casting process. ahmed a. moosa!!!!! al-khwarizmi engineering journal, vol. 6, no. 1, pp 57-68 (2010) 58 kiourtsidis et al. [8] showed a decrease in the dendritic size of 8-24 vol ٪ sic particles/2024 al alloy with increasing the sic volume fraction. also they studied the corrosion behavior of that composite, and they found no galvanic interaction between sic and the matrix, instead there is an anodic reaction which is independent of the sic volume fraction. the aim of this work is to study the preparation of y2o3/al-si and cr2o3/al-si composites by direct squeeze casting process. 2. experimental procedures 2.1. materials and methods the composite materials used in this work are al-si eutectic alloy with yttrium oxide and with chromium oxide particles as reinforcements. a standard aluminum-silicon eutectic alloy type 1725 din [9] was used in this work as the matrix of the composites. this alloy has good bearing properties, good fluidity and low coefficient of thermal expansion with a density of 2.68 g/cm3. it is a common alloy used in the production of pistons [10,11]. table (1) shows the chemical composition of the alloy. the analysis was done by using the atomic absorption apparatus at the ministry of science and technology in baghdad, iraq. table 1, chemical composition of the a119-1725 al-si alloy. si fe cu mn mg zn ti al 12.1 0.65 0.83 0.2 0.27 0.45 0.02 bal. chromium oxide powder with particle size (50-75) μm and yttrium oxide powder with particle size (50-75) μm were used as reinforcements. the particle size was measured by sieving method. the density of the chromium oxide powder and yttrium oxide powder are (3.404 and 2.65 gm/cm3) respectively as determined by taking the weight and volume of a green packed powder in a cylindrical form and using the formula [12 ]: ρ = m/v …(1) where ρ is the density gm/ cm3, m = mass (gm), v= volume (cm3) . the squeeze casting system consists of hydraulic press, squeeze die and auxiliary equipment. a vertical hydraulic press is used (with a ram 70 mm in diameter) to apply a pressure of (1-100) kg/cm2 in a perpendicular direction to the squeeze casting die. the squeeze punch was made from hot forming steel, and designed with a hole in its upper part to be fixed to the ram with two steel bolts. the lower part of the ram is a rectangular in shape with a semicircle ends which is used to squeeze the molten alloy. the die is horizontal and consists of two parts joined by four high temperature resistant steel bolts. this design allows the final squeezed composite casting to be removed from the die easily. figure (1) shows the punch and the die. fig.1. the punch and die used in squeeze casting. the standard al-si alloy was melted in an electrical furnace. a calibrated ktype thermocouple is used to measure the temperature with an accuracy of ± 1oc. a box type electrical heating furnace (carbolite co, england) was used to heat the reinforcement particles. the standard al-si alloy was melted using an electrical furnace at the required temperature using alumina crucible. the experiments were done at the university of technology. the chromium oxide particles (3.1, 6.3, 9.4, 12.5 vol. %) or yttrium oxide particles (4, 8.1, 12.1, 16.1 vol %) were wrapped in a high purity al foils and heated to 300oc for 15 minutes in the heating furnace. the heated aluminum foil with the chromium oxide particles or with the yttrium oxide particles were then added to the molten alsi alloy and the mixture was stirred for 3 minutes using an electrical stirrer (type rw20-janke & kunkel co, germany) at speed 500 rpm. then the molten al-si alloy with chromium oxide particles or with yttrium oxide particles was put again in the melting furnace. the squeeze casting die was then preheated to the required preheating temperatures (200)˚c. the preheated die was then placed on the hydraulic press table. the molten al-si alloy with chromium oxide particles was ahmed a. moosa!!!!! al-khwarizmi engineering journal, vol. 6, no. 1, pp 57-68 (2010) 59 stirred again using an electrical stirrer at speed 500 rpm and the molten alloy was poured into the squeeze die cavity. the pouring temperatures that used for all castings are (700)˚c. the required squeeze pressure was then applied for 30 seconds at a delay time of 5 seconds and allowing for solidification. the hydraulic pressures that are used for all castings are (53) mpa. after that the solidified composite casting was removed from the die. the al-si squeeze cast composites were cut into rectangular samples with dimensions 1x1x0.5 cm3. each specimen was wet ground with silicon carbide papers 1000 grit using grinding machine (struers dap-5, denmark) and then polished on polishing clothes using 5.0 m and 0.3 m alumina suspension sequentially. each specimen was then washed with water and alcohol, and etched by a dilute hf acid (1٪ distilled water and 99٪ hf). the microstructure was examined by an optical microscope (100wcarlzeiss jena, germany) with a digital camera type (smartic with 5 mega pixels resolution). 2.2. density measurements two types of density were calculated as follows: 1) theoretical density calculation the following mixture formula was used to calculate the theoretical density of the composites [13]: ρc = ρm fm + ρr fr …(2) where ρc : composite density ρm : matrix density fm : matrix volume fraction ρr : reinforcement density fr : reinforcement volume fraction 2) practical density calculation the practical density (ρp) can be calculated from formula (1) 2.3. porosity the porosity of the al-si composite was calculated for all specimens using the following formula [14]: p = [1 – (ρp / ρc )] * 100 …(3) where: p= porosity % ρp = practical density ρc= composite density 2.4. microhardness test the microhardness of each specimen was measured by using vickers microhardness apparatus provided by the materials engineering department, university of technology. vickers hardness number was calculated by the following equation [15]: hv = 1.8544 [ p / (dav) 2 ] …(4) where: p : the applied load = 1 kg dav : the average diameter of the two diagonal length of the rhombus indentation for each specimen three hardness measurements were taken and the average hardness was calculated. 2.5. wear test dry sliding wear tests were conducted for the graphite particles reinforced al-si matrix composite specimens on the pin-on-disc apparatus. a cylindrical wear specimen was used with a diameter of 10 mm and a length of 20 mm. the specimen slides on a carbon steel disc with a hardness of 38 hrc. wear rates were calculated from the following formula [8]: wear rate (wr) = δw / 2πrnρprt …(5) and δw = w1 – w2 …(6) where: wr : wear rate (cm3/cm) w1 : specimen weight before the wear test (gm). w2 : specimen weight after the wear test (gm). r : the distance from the center of the specimen to the center of the steel disc = 7 cm. n : the number of cycles for the steel disc =512 rpm. ρpr : the practical density of the composite specimens (gm/cm3). t : the sliding time ( 20 minutes) . the applied load used in this test was 10 n. ahmed a. moosa!!!!! al-khwarizmi engineering journal, vol. 6, no. 1, pp 57-68 (2010) 60 3. results and discussion 3.1. microstructure figure (2) shows the microstructure of gravity cast commercial al-12٪si alloy and figure (3) shows the microstructure of squeeze cast al12٪si alloy. it consists of α-aluminum dendrites (white) surrounded by eutectic phase and primary silicon particles (light gray). the microstructure in figure (3) is refined due to the effect of squeeze conditions in the faster cooling rate and hence smaller eutectic and dendrites. fig.2. unreinforced al-si alloy. fig.3. squeeze cast al-si alloy fig.4. 2wt٪ y2o3/al-si composite. fig.5. 4wt٪ y2o3/al-si composite the microstructures of the y2o3 reinforced alsi matrix composites and cr2o3 reinforced al-si matrix composites are shown in figures (4-7) and (8-11) respectively. the microstructure reveals that there are small discontinuities and a reasonably uniform distribution of y2o3 particulates and more uniform distribution of the cr2o3 particles. the ceramic phase is shown as dark phase. the quantity and distribution of reinforcement particles differ from figure to figure since they depend primarily on the composite preparation before applying squeeze casting process. the microstructures of these mmcs show that the primary aluminum tends to avoid the discontinuous phase and nucleates in the interstices between particles. primary aluminum crystallized from the melt does not nucleate on the particle surface, because of surface thermodynamics and solute. the primary αaluminum grows by rejecting solute in the melt, while the reinforcing particles tend to restrict diffusion and fluid flow; therefore, α-aluminum tends to avoid it [16,17]. it can be seen from these figures that the squeeze pressure are capable of producing good bonding between the particles and the matrix alloy. this is concluded from the absence of any cavities that can result from the pull out of these particles during the specimen ahmed a. moosa!!!!! al-khwarizmi engineering journal, vol. 6, no. 1, pp 57-68 (2010) 61 preparation process for the microstructure examination. increasing the volume fraction of the y2o3 particles and cr2o3 particles have led to more refinement in the microstructure as can be seen in figures (7) and (11) respectively which is in agreement with the findings of long [18]. fig.6. 6wt٪ y2o3/al-si composite. fig.7. 8wt٪ y2o3/al-si composite fig.8. 2wt٪ cr2o3/al-si composite fig.9. 4wt٪ cr2o3/al-si composite fig.10. 6wt٪cr2o3/al-si composite. fig.11. 8wt٪cr2o3/al-si composite ahmed a. moosa!!!!! al-khwarizmi engineering journal, vol. 6, no. 1, pp 57-68 (2010) 62 3.2. density and porosity table (2) shows the values of density and porosity for the unreinforced alloy and the squeeze cast alloy and composites. it is clear that the density of the y2o3/al-si composites is lower than that of the unreinforced alloy since y2o3 particles have lower density than that of the al-si alloy, while the density of the cr2o3/al-si composites is higher than that of the unreinforced alloy since cr2o3 particles have higher density. figure (12) illustrates the relationship between density and volume fraction of the y2o3 particles. this figure shows that the density decreases slightly with increasing particle volume fraction. also the practical values of density is less than the theoretical ones due to the presence of shrinkage and gas porosities as confirmed in table (2) and figure (13). figure (14) illustrates the relationship between density and cr2o3 particles volume fraction. it shows that the density increases with increasing the volume fraction since cr2o3 have higher density as mentioned before. figure (15) illustrates the porosity versus cr2o3 volume fraction and it shows the decreasing in porosity with the volume fraction. this is due to the tendency of the particles to segregate and to the increasing of the cooling rate of the casting which can produce more shrinkage porosity. this result indicates that the used squeeze pressure was not enough to eliminate or reduce such porosity at the higher used volume fraction. table 2, density and porosity of the alloy and the composites squeeze cast at 700˚c pouring temperature, 200˚c die temperature and 53 mpa squeeze pressure for 30 sec. material theoretical density (gm/cm3) practical density (gm/cm3) porosity (٪) al-si alloy 2.68 2.644 1.3 2wt٪y2o3/al-si composite 2.6788 2.58 3.7 4wt٪y2o3/al-si composite 2.6776 2.49 7 6wt٪y2o3/al-si composite 2.6764 2.42 9.6 8wt٪y2o3/al-si composite 2.6752 2.39 10.7 2wt٪cr2o3/alsicomposite 2.7 2.646 2 4wt٪cr2o3/alsicomposite 2.726 2.658 2.5 6wt٪cr2o3/alsicomposite 2.75 2.68 2.6 8wt٪cr2o3/alsicomposite 2.771 2.689 3 ahmed a. moosa!!!!! al-khwarizmi engineering journal, vol. 6, no. 1, pp 57-68 (2010) 63 fig.12. density versus y2o3 volume fraction. fig.13. porosity versus y2o3 volume fraction. fig.14. density versus cr2o3 volume fraction. y = -0.0003x + 2.68 r2 = 1 y = 0.0004x2 0.0227x + 2.6508 r2 = 0.9908 2.3 2.4 2.5 2.6 2.7 0 5 10 15 20 y2o3 volume fraction (vol.%) d en si ty ( ρ )( g /c m 3 ) ρ theoretical ρ practical linear (ρ theoretical) poly. (ρ practical) y = -0.0143x2 + 0.8434x + 1.0563 r2 = 0.9912 0 5 10 15 0 5 10 15 20 y2o3 volume fraction (vol.%) p o ro si ty ( % ) yth = 0.0074x + 2.679 r2 = 0.9987 yp = 0.0002x2 + 0.0017x + 2.6421 r2 = 0.9638 2.6 2.65 2.7 2.75 2.8 0 5 10 15 cr2o3 volume fraction (vol.%) d en si ty ( ρ )( g /c m 3 ) ρ theoretical ρ practical poly. (ρ practical) ahmed a. moosa!!!!! al-khwarizmi engineering journal, vol. 6, no. 1, pp 57-68 (2010) 64 fig.15. porosity versus cr2o3 volume fraction. 3.3. hardness table (3) shows the values of vickers microhardness for the squeeze cast unreinforced alloy and the composites. this table shows that the composites have higher hardness than the alsi alloy due to the effect of squeeze casting and particles addition in increasing the cooling rate and refining the microstructure. figures (16 and 17) illustrate the relationship between hardness and particles volume fraction for they2o3/al-si composites and cr2o3/al-si composites respectively. figure (16) shows that the hardness is maximum at 8 volume percentage of y2o3. figure (17) shows that the hardness is maximum at a 7.6 volume percentage of cr2o3. the lower value of hardness at these percents is due to the segregation of the particles which may result from composite preparation during casting, and the higher amount of porosity at the higher used volume fraction. this is also consistence with wear rate test. the minimum wear rates for they2o3/al-si composites and cr2o3/al-si also occur at a volume percentage of 8 and 7.6 for both types of composites respectively. table 3, microhardness of the alloy and the composites squeeze cast at 700˚c pouring temperature, 200˚c die temperature and 53 mpa squeeze pressure for 30 sec. materials vickers microhardness no. al-si alloy 69 2wt٪y2o3/al-si composites 117 4wt٪y2o3/al-si composites 72.4 6wt٪y2o3/al-si composites 129 8wt٪y2o3/al-si composites 69.3 2wt٪cr2o3/al-si composites 98.7 4wt٪cr2o3/al-si composites 86.2 6wt٪cr2o3/al-si composites 104 8wt٪cr2o3/al-si composites 80.1 fig.16. hardness versus y2o3 volume fraction. y = -0.0072x2 + 0.2184x + 1.339 r2 = 0.9785 0 1 2 3 4 0 5 10 15 cr2o3 volume fraction (vol.%) p o ro si ty ( % ) y = -0.627x2 + 10.325x + 71.733 r2 = 0.5129 0 50 100 150 0 10 20 y2o3 volume fraction (vol.%) m ic ro h a rd n e s s (v h n ) ahmed a. moosa!!!!! al-khwarizmi engineering journal, vol. 6, no. 1, pp 57-68 (2010) 65 fig.17. hardness versus cr2o3 volume fraction. 3.4. wear rate table (4) shows the values of wear rate for the squeeze cast unreinforced alloy and the composites. it shows that the composites have lower wear rate than that of the unreinforced alloy due to the squeeze casting and particles effect on increasing the hardness and refining the microstructure. figures (18 and 19) illustrate the relationship between wear rate and particles volume fraction for they2o3/al-si composites and cr2o3/al-si composites respectively. from these figures and table (4), it can be seen that the minimum wear rates for they2o3/al-si composites and cr2o3/alsi also occur at a volume percentage of 8 and 7.6 respectively. this is in agreement with the results of microhardness in which higher hardness had led to lower wear rate. table 4, wear rate of the alloy and the composites squeeze cast at 700˚c pouring temperature, 200˚c die temperature and 53 mpa squeeze pressure for 30 sec. material wear rate (cm3/cm) *10-9 al-si alloy 13.53 2wt٪y2o3/al-si composites 7.66 4wt٪y2o3/al-si composites 8.74 6wt٪y2o3/al-si composites 7.44 8wt٪y2o3/al-si composites 13.01 2wt٪cr2o3/al-si composites 6.8 4wt٪cr2o3/al-si composites 7.44 6wt٪cr2o3/al-si composites 5.2 8wt٪cr2o3/al-si composites 9 fig.18. wear rate versus y2o3 volume fraction. y = -0.5612x2 + 7.8872x + 71.215 r2 = 0.6204 0 50 100 150 0 5 10 15 cr2o3 volume fraction (vol.%) m ic ro h a rd n es s ( v h n ) y = 0.0904x2 1.4865x + 13.246 r2 = 0.8572 0 5 10 15 0 5 10 15 20 y2o3 volume fraction (vol.%) w ea r r at e (c m 3 /c m ) *1 0-9 ahmed a. moosa!!!!! al-khwarizmi engineering journal, vol. 6, no. 1, pp 57-68 (2010) 66 fig.19. wear rate versus cr2o3 volume fraction. 4. conclusions 1) the al-si alloy produced by squeeze casting has refined microstructure and a density close to the theoretical one. 2) the y2o3/al-si composites and cr2o3/al-si composites produced by squeeze casting have more microstructure refinement, higher hardness and lower wear rate than the unreinforced alloy. 3) the density decreases slightly with increasing particle volume fraction for y2o3/al-si composites. 4) the density increases with increasing the volume fraction for cr2o3/al-si composites. 5. references [1] dionne s., “influence of titanium diboride reinforcements on the microstructure, mechanical properties and fracture behavior of cast zinc-aluminum composites” ph.d. thesis, department des mines et metallurgie, faculte des sciences et de genie, universite laval, quebec, canada, sept. 1999. [2] hong c.p., shen h.f., cho i.s., “prevention of macrosegregation in squeeze casting of an al-4.5wt cu alloy” met. mat. trans., vol. 29a, jan. 1998, pp. 339-349. [3] long s., beffort o., moret g., thevoz ph., “processing of al-based mmcs by indirect squeeze infiltration of ceramic performs on a shot-control high pressure die casting machine” j. mat. sci. eng., 1999, pp. 1-10. [4] prakasan k., seshan s., “microstructure and properties of squeeze cast cu/carbon fiber metal matrix composite” j. mat. sci., vol. 34, 1999, pp. 5045-5049. [5] zhang x.x., wang d.z., geng l.,“coarsening of eutectic silicon in squeeze cast alumina fiber reinforced eutectic al-si aluminum composites” j. mat. sci. lett., vol. 22, 2003, pp. 861-863. [6] etter t., kuebler j., frey t., schulz p., loffler j.f., uggowitzer p.j., “strength and fracture toughness of interpenetrating graphite/aluminum composites produced by the indirect squeeze casting process” mat. sci. eng, vol. a386, 2004, pp. 61-67. 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[11] takhakh a.m., “solidification simulation and experimental investigation of al-si cast structures” ph.d. thesis, department of production engineering and metallurgy, y = 0.1328x2 1.9993x + 13.105 r2 = 0.8618 0 5 10 15 0 5 10 15 cr2o3 volume fraction (vol.%) w ea r r at e (c m 3 /c m ) *1 0-9 ahmed a. moosa!!!!! al-khwarizmi engineering journal, vol. 6, no. 1, pp 57-68 (2010) 67 university of technology, baghdad, iraq, 2007. [12] bolton w., “engineering materials technology” third edition, butterworth heinemann, 1998, p. 4. [13] meyers m.a., chawla k.k., “mechanical behavior of materials” prentice-hall, inc., usa, 1999, p. 644. [14] abtan n.s., “a study on squeeze casting parameters effects on improving the metallurgical and mechanical properties of aluminum alloys” ph.d. thesis, dept. of production engineering and metallurgy, university of technology, baghdad, iraq, 2007. [15] callister w.d.jr., “materials science and engineering, an introduction” fifth edition, john wiley & sons, inc., 2000, p. 136. [16] al-kaaby a.s.j., “preparation and characterization of cast aluminum matrix sic particulate composite” ph.d. thesis, department of production engineering and metallurgy, university of technology, baghdad, iraq, nov. 2000. [17] rooy e.l., “aluminum and aluminum alloys” asm metals handbook, casting, 9th edition, 4th printing, vol. 15, materials park, oh, 1998. [18] long s, beffort o., cayron c., bonjour c., “microstructure and mechanical properties of a high volume fraction sic particle reinforced alcu4mgag squeeze casting” mat. sci. eng., vol. a, 1999. )2010( 68 57، صفحة 1، العدد 6مجلة الخوارزمي الھندسیة المجلد احمد علي موسى 68 وكسید أسلیكون المقواة ب -التركیب المجھري وبعض الخصائص للمواد المتراكبة نوع االلمنیوم وكسید االلومیناأ وااالیتریوم احمد علي موسى التكنولوجیة ةالجامع /قسم ھندسة االنتاج والمعادن ةصالخال بیكة اال تحضیردراسة تم ن س وم لمادة متراكبة ذات اساس م لیكون -منی روم م س ید الك دقائق اوكس واة ب وم لاال(ق لیكون -منی روم / س ید الك ائق ) اوكس و دق ,3.1مختلفة من دقائق اوكسید الكرومكسور حجمیة تم اضافة . بطریقة السباكة بالعصر المباشر) اوكسید االیتریوم / سلیكون -منیوملاال(اوكسید االیتریوم 6.3 , 9.4, 12.5 vol %) ( ة وكذلك اضافة ور حجمی وم كس ید االیتری ن اوكس ة م ھر . (% vol 16.1 ,12.1 ,8.1 ,4)مختلف ط منص ة خل ت عملی اجری رعة ااوكسید الكروم ب/ سلیكون -منیوملاال اوكسید االیتریوم او منصھر سبیكة/ سلیكون -منیوملاال سبیكة ائي وبس الط كھرب ة /دورة ٥٠٠ستخدام خ . دقیق ر تم استعمال المتغیرا غط العص ب )53mpa(ت مثل ض رارة الص ة ح بس )c˚700(، درج ن الك ث ) .30sec(، زم ن التری رارة )..5sec(وزم ة ح ودرج c˚200)القالب واة . معدل البلى الصالدة وتم فحص البنیة المجھریة للمواد المتراكبة ،. ( بائك المق ي الس ة ف ة المجھری ي البنی اظھرت النتائج حصول تنعیم ف .كما اظھرت النتائج زیادة في الصالدة وانخفاض في معدل البلى في السبائك المقواة مقارنة مع السبیكة غیر المقواة . مقواة الالسبیكة غیر مقارنة مع m m m m y = -0.0003x + 2.68 r 2 = 1 y = 0.0004x 2 0.0227x + 2.6508 r 2 = 0.9908 2.3 2.4 2.5 2.6 2.7 05101520 y 2 o 3 volume fraction (vol.%) density (ρ)(g/cm 3 ) ρ theoretical ρ practical linear (ρ theoretical) poly. (ρ practical) y = -0.0143x 2 + 0.8434x + 1.0563 r 2 = 0.9912 0 5 10 15 05101520 y 2 o 3 volume fraction (vol.%) porosity (%) y th = 0.0074x + 2.679 r 2 = 0.9987 y p = 0.0002x 2 + 0.0017x + 2.6421 r 2 = 0.9638 2.6 2.65 2.7 2.75 2.8 051015 cr 2 o 3 volume fraction (vol.%) density (ρ)(g/cm 3 ) ρ theoretical ρ practical poly. (ρ practical) y = -0.0072x 2 + 0.2184x + 1.339 r 2 = 0.9785 0 1 2 3 4 051015 cr 2 o 3 volume fraction (vol.%) porosity (%) y = -0.627x 2 + 10.325x + 71.733 r 2 = 0.5129 0 50 100 150 01020 y 2 o 3 volume fraction (vol.%) microhardness (vhn) y = -0.5612x 2 + 7.8872x + 71.215 r 2 = 0.6204 0 50 100 150 051015 cr 2 o 3 volume fraction (vol.%) microhardness (vhn) y = 0.0904x 2 1.4865x + 13.246 r 2 = 0.8572 0 5 10 15 05101520 y 2 o 3 volume fraction (vol.%) wear rate (cm 3 /cm) *10 -9 y = 0.1328x 2 1.9993x + 13.105 r 2 = 0.8618 0 5 10 15 051015 cr 2 o 3 volume fraction (vol.%) wear rate (cm 3 /cm) *10 -9 ahmed a. moosa al-khwarizmi engineering journal, vol. 6, no. 1, pp 57-68 (2010) al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 6, no. 1, pp 57-68 (2010) microstructure and some properties of aluminum-silicon matrix composites reinforced by alumina or chromia ahmed a. moosa department of production engineering and metallurgy/ university of technology (received 13 july 2009: accepted 6 september 2009) abstract in this work, yttrium oxide particles (powder) reinforced al-si matrix composites (y2o3/al-si) and chromium oxide particles reinforced al-si matrix composites (cr2o3/al-si) were prepared by direct squeeze casting. the volume percentages of yttrium oxide used are (4, 8.1, 12.1, 16.1 vol %) and the volume percentages of the chromium oxide particles used are (3.1, 6.3, 9.4, 12.5 vol. %). the parameters affecting the preparation of y2o3/al-si and cr2o3/al-si composites by direct squeeze casting process were studied. the molten al-si alloy with yttrium oxide particles or with chromium oxide particles was stirred again using an electrical stirrer at speed 500 rpm and the molten alloy was poured into the squeeze die cavity. the pouring temperature that used for all castings is (700)˚c. the required squeeze pressure, 53 mpa, was then applied for 30 seconds at a delay time of 5. the die temp is (200˚c). the y2o3/al-si composites and cr2o3/al-si composites produced by squeeze casting have more microstructure refinement, higher hardness and lower wear rate than the unreinforced alloy. keywords: composite, microstructure, al-si , yttria , alumina 1. introduction the squeeze casting technique produces parts with reduced porosity levels because of the high pressure applied during solidification and due to efficient liquid feeding obtained by moving the ram to compensate for the freezing contraction. the cooling rate of the casting can be increased by applying high pressure during solidification due to increase in thermal conductivity [1, 2]. metal matrix composites (mmcs) of metallic alloys reinforced with ceramics particles are designed to offer high specific mechanical properties that are highly desirable in various applications and provide a relatively novel way of strengthening metals [3,4]. aluminum/silicon alloys are known for their high strength to weight ratio, good castability, low thermal expansion and high corrosion resistance. these properties have led to their application in all types of internal combustion engines as pistons, cylinder blocks and cylinder heads. al-si matrix composites are composed of al-si alloy matrix, and reinforcement. reinforcements added to al-alloy matrices include intermetallic compounds, ceramic phases such as oxides, carbides and nitrides as well as refractory metals[5]. particle reinforced composites are characterized by particles having a diameter greater than 1 µm with a volume fraction of 5 to 40%. particle reinforced composites show isotropic stiffness improvements with generally lesser degradation of fracture properties than that of whisker reinforced mmcs [1]. etter et al. [6] also examined graphite particles with al-si alloy prepared by squeeze casting, but with different si content. they concluded an increase in the mechanical strength and fracture toughness by using this process and with si addition. long et al. [7] showed an increase in the mechanical properties (stiffness, hardness, and fatigue strength and wear resistance) before and after heat treatment of 60wt٪ sic particles /al-cu-mg-ag alloy. this was related directly to the addition of sic particles and squeeze casting process. kiourtsidis et al. [8] showed a decrease in the dendritic size of 8-24 vol ٪ sic particles/2024 al alloy with increasing the sic volume fraction. also they studied the corrosion behavior of that composite, and they found no galvanic interaction between sic and the matrix, instead there is an anodic reaction which is independent of the sic volume fraction. the aim of this work is to study the preparation of y2o3/al-si and cr2o3/al-si composites by direct squeeze casting process. 2. experimental procedures 2.1. materials and methods the composite materials used in this work are al-si eutectic alloy with yttrium oxide and with chromium oxide particles as reinforcements. a standard aluminum-silicon eutectic alloy type 1725 din [9] was used in this work as the matrix of the composites. this alloy has good bearing properties, good fluidity and low coefficient of thermal expansion with a density of 2.68 g/cm3. it is a common alloy used in the production of pistons [10,11]. table (1) shows the chemical composition of the alloy. the analysis was done by using the atomic absorption apparatus at the ministry of science and technology in baghdad, iraq. table 1, chemical composition of the a119-1725 al-si alloy. si fe cu mn mg zn ti al 12.1 0.65 0.83 0.2 0.27 0.45 0.02 bal. chromium oxide powder with particle size (50-75) μm and yttrium oxide powder with particle size (50-75) μm were used as reinforcements. the particle size was measured by sieving method. the density of the chromium oxide powder and yttrium oxide powder are (3.404 and 2.65 gm/cm3) respectively as determined by taking the weight and volume of a green packed powder in a cylindrical form and using the formula [12 ]: ρ = m/v …(1) where ρ is the density gm/ cm3, m = mass (gm), v= volume (cm3) . the squeeze casting system consists of hydraulic press, squeeze die and auxiliary equipment. a vertical hydraulic press is used (with a ram 70 mm in diameter) to apply a pressure of (1-100) kg/cm2 in a perpendicular direction to the squeeze casting die. the squeeze punch was made from hot forming steel, and designed with a hole in its upper part to be fixed to the ram with two steel bolts. the lower part of the ram is a rectangular in shape with a semicircle ends which is used to squeeze the molten alloy. the die is horizontal and consists of two parts joined by four high temperature resistant steel bolts. this design allows the final squeezed composite casting to be removed from the die easily. figure (1) shows the punch and the die. fig.1. the punch and die used in squeeze casting. the standard al-si alloy was melted in an electrical furnace. a calibrated ktype thermocouple is used to measure the temperature with an accuracy of ± 1oc. a box type electrical heating furnace (carbolite co, england) was used to heat the reinforcement particles. the standard al-si alloy was melted using an electrical furnace at the required temperature using alumina crucible. the experiments were done at the university of technology. the chromium oxide particles (3.1, 6.3, 9.4, 12.5 vol. %) or yttrium oxide particles (4, 8.1, 12.1, 16.1 vol %) were wrapped in a high purity al foils and heated to 300oc for 15 minutes in the heating furnace. the heated aluminum foil with the chromium oxide particles or with the yttrium oxide particles were then added to the molten al-si alloy and the mixture was stirred for 3 minutes using an electrical stirrer (type rw20-janke & kunkel co, germany) at speed 500 rpm. then the molten al-si alloy with chromium oxide particles or with yttrium oxide particles was put again in the melting furnace. the squeeze casting die was then preheated to the required preheating temperatures (200)˚c. the preheated die was then placed on the hydraulic press table. the molten al-si alloy with chromium oxide particles was stirred again using an electrical stirrer at speed 500 rpm and the molten alloy was poured into the squeeze die cavity. the pouring temperatures that used for all castings are (700)˚c. the required squeeze pressure was then applied for 30 seconds at a delay time of 5 seconds and allowing for solidification. the hydraulic pressures that are used for all castings are (53) mpa. after that the solidified composite casting was removed from the die. the al-si squeeze cast composites were cut into rectangular samples with dimensions 1x1x0.5 cm3. each specimen was wet ground with silicon carbide papers 1000 grit using grinding machine (struers dap-5, denmark) and then polished on polishing clothes using 5.0 and 0.3 alumina suspension sequentially. each specimen was then washed with water and alcohol, and etched by a dilute hf acid (1٪ distilled water and 99٪ hf). the microstructure was examined by an optical microscope (100wcarlzeiss jena, germany) with a digital camera type (smartic with 5 mega pixels resolution). 2.2. density measurements two types of density were calculated as follows: 1) theoretical density calculation the following mixture formula was used to calculate the theoretical density of the composites [13]: ρc = ρm fm + ρr fr …(2) where ρc : composite density ρm : matrix density fm : matrix volume fraction ρr : reinforcement density fr : reinforcement volume fraction 2) practical density calculation the practical density (ρp) can be calculated from formula (1) 2.3. porosity the porosity of the al-si composite was calculated for all specimens using the following formula [14]: p = [1 – (ρp / ρc )] * 100 …(3) where: p= porosity % ρp = practical density ρc= composite density 2.4. microhardness test the microhardness of each specimen was measured by using vickers microhardness apparatus provided by the materials engineering department, university of technology. vickers hardness number was calculated by the following equation [15]: hv = 1.8544 [ p / (dav)2 ] …(4) where: p : the applied load = 1 kg dav : the average diameter of the two diagonal length of the rhombus indentation for each specimen three hardness measurements were taken and the average hardness was calculated. 2.5. wear test dry sliding wear tests were conducted for the graphite particles reinforced al-si matrix composite specimens on the pin-on-disc apparatus. a cylindrical wear specimen was used with a diameter of 10 mm and a length of 20 mm. the specimen slides on a carbon steel disc with a hardness of 38 hrc. wear rates were calculated from the following formula [8]: wear rate (wr) = δw / 2πrnρprt …(5) and δw = w1 – w2 …(6) where: wr : wear rate (cm3/cm) w1 : specimen weight before the wear test (gm). w2 : specimen weight after the wear test (gm). r : the distance from the center of the specimen to the center of the steel disc = 7 cm. n : the number of cycles for the steel disc =512 rpm. ρpr : the practical density of the composite specimens (gm/cm3). t : the sliding time ( 20 minutes) . the applied load used in this test was 10 n. 3. results and discussion 3.1. microstructure figure (2) shows the microstructure of gravity cast commercial al-12٪si alloy and figure (3) shows the microstructure of squeeze cast al-12٪si alloy. it consists of α-aluminum dendrites (white) surrounded by eutectic phase and primary silicon particles (light gray). the microstructure in figure (3) is refined due to the effect of squeeze conditions in the faster cooling rate and hence smaller eutectic and dendrites. fig.2. unreinforced al-si alloy. fig.3. squeeze cast al-si alloy fig.4. 2wt٪ y2o3/al-si composite. fig.5. 4wt٪ y2o3/al-si composite the microstructures of the y2o3 reinforced al-si matrix composites and cr2o3 reinforced al-si matrix composites are shown in figures (4-7) and (8-11) respectively. the microstructure reveals that there are small discontinuities and a reasonably uniform distribution of y2o3 particulates and more uniform distribution of the cr2o3 particles. the ceramic phase is shown as dark phase. the quantity and distribution of reinforcement particles differ from figure to figure since they depend primarily on the composite preparation before applying squeeze casting process. the microstructures of these mmcs show that the primary aluminum tends to avoid the discontinuous phase and nucleates in the interstices between particles. primary aluminum crystallized from the melt does not nucleate on the particle surface, because of surface thermodynamics and solute. the primary α-aluminum grows by rejecting solute in the melt, while the reinforcing particles tend to restrict diffusion and fluid flow; therefore, α-aluminum tends to avoid it [16,17]. it can be seen from these figures that the squeeze pressure are capable of producing good bonding between the particles and the matrix alloy. this is concluded from the absence of any cavities that can result from the pull out of these particles during the specimen preparation process for the microstructure examination. increasing the volume fraction of the y2o3 particles and cr2o3 particles have led to more refinement in the microstructure as can be seen in figures (7) and (11) respectively which is in agreement with the findings of long [18]. fig.6. 6wt٪ y2o3/al-si composite. fig.7. 8wt٪ y2o3/al-si composite fig.8. 2wt٪ cr2o3/al-si composite fig.9. 4wt٪ cr2o3/al-si composite fig.10. 6wt٪cr2o3/al-si composite. fig.11. 8wt٪cr2o3/al-si composite 3.2. density and porosity table (2) shows the values of density and porosity for the unreinforced alloy and the squeeze cast alloy and composites. it is clear that the density of the y2o3/al-si composites is lower than that of the unreinforced alloy since y2o3 particles have lower density than that of the al-si alloy, while the density of the cr2o3/al-si composites is higher than that of the unreinforced alloy since cr2o3 particles have higher density. figure (12) illustrates the relationship between density and volume fraction of the y2o3 particles. this figure shows that the density decreases slightly with increasing particle volume fraction. also the practical values of density is less than the theoretical ones due to the presence of shrinkage and gas porosities as confirmed in table (2) and figure (13). figure (14) illustrates the relationship between density and cr2o3 particles volume fraction. it shows that the density increases with increasing the volume fraction since cr2o3 have higher density as mentioned before. figure (15) illustrates the porosity versus cr2o3 volume fraction and it shows the decreasing in porosity with the volume fraction. this is due to the tendency of the particles to segregate and to the increasing of the cooling rate of the casting which can produce more shrinkage porosity. this result indicates that the used squeeze pressure was not enough to eliminate or reduce such porosity at the higher used volume fraction. table 2, density and porosity of the alloy and the composites squeeze cast at 700˚c pouring temperature, 200˚c die temperature and 53 mpa squeeze pressure for 30 sec. material theoretical density (gm/cm3) practical density (gm/cm3) porosity (٪) al-si alloy 2.68 2.644 1.3 2wt٪y2o3/al-si composite 2.6788 2.58 3.7 4wt٪y2o3/al-si composite 2.6776 2.49 7 6wt٪y2o3/al-si composite 2.6764 2.42 9.6 8wt٪y2o3/al-si composite 2.6752 2.39 10.7 2wt٪cr2o3/al-sicomposite 2.7 2.646 2 4wt٪cr2o3/al-sicomposite 2.726 2.658 2.5 6wt٪cr2o3/al-sicomposite 2.75 2.68 2.6 8wt٪cr2o3/al-sicomposite 2.771 2.689 3 fig.12. density versus y2o3 volume fraction. fig.13. porosity versus y2o3 volume fraction. fig.14. density versus cr2o3 volume fraction. fig.15. porosity versus cr2o3 volume fraction. 3.3. hardness table (3) shows the values of vickers microhardness for the squeeze cast unreinforced alloy and the composites. this table shows that the composites have higher hardness than the al-si alloy due to the effect of squeeze casting and particles addition in increasing the cooling rate and refining the microstructure. figures (16 and 17) illustrate the relationship between hardness and particles volume fraction for they2o3/al-si composites and cr2o3/al-si composites respectively. figure (16) shows that the hardness is maximum at 8 volume percentage of y2o3. figure (17) shows that the hardness is maximum at a 7.6 volume percentage of cr2o3. the lower value of hardness at these percents is due to the segregation of the particles which may result from composite preparation during casting, and the higher amount of porosity at the higher used volume fraction. this is also consistence with wear rate test. the minimum wear rates for they2o3/al-si composites and cr2o3/al-si also occur at a volume percentage of 8 and 7.6 for both types of composites respectively. table 3, microhardness of the alloy and the composites squeeze cast at 700˚c pouring temperature, 200˚c die temperature and 53 mpa squeeze pressure for 30 sec. materials vickers microhardness no. al-si alloy 69 2wt٪y2o3/al-si composites 117 4wt٪y2o3/al-si composites 72.4 6wt٪y2o3/al-si composites 129 8wt٪y2o3/al-si composites 69.3 2wt٪cr2o3/al-si composites 98.7 4wt٪cr2o3/al-si composites 86.2 6wt٪cr2o3/al-si composites 104 8wt٪cr2o3/al-si composites 80.1 fig.16. hardness versus y2o3 volume fraction. fig.17. hardness versus cr2o3 volume fraction. 3.4. wear rate table (4) shows the values of wear rate for the squeeze cast unreinforced alloy and the composites. it shows that the composites have lower wear rate than that of the unreinforced alloy due to the squeeze casting and particles effect on increasing the hardness and refining the microstructure. figures (18 and 19) illustrate the relationship between wear rate and particles volume fraction for they2o3/al-si composites and cr2o3/al-si composites respectively. from these figures and table (4), it can be seen that the minimum wear rates for they2o3/al-si composites and cr2o3/al-si also occur at a volume percentage of 8 and 7.6 respectively. this is in agreement with the results of microhardness in which higher hardness had led to lower wear rate. table 4, wear rate of the alloy and the composites squeeze cast at 700˚c pouring temperature, 200˚c die temperature and 53 mpa squeeze pressure for 30 sec. material wear rate (cm3/cm) *10-9 al-si alloy 13.53 2wt٪y2o3/al-si composites 7.66 4wt٪y2o3/al-si composites 8.74 6wt٪y2o3/al-si composites 7.44 8wt٪y2o3/al-si composites 13.01 2wt٪cr2o3/al-si composites 6.8 4wt٪cr2o3/al-si composites 7.44 6wt٪cr2o3/al-si composites 5.2 8wt٪cr2o3/al-si composites 9 fig.18. wear rate versus y2o3 volume fraction. fig.19. wear rate versus cr2o3 volume fraction. 4. conclusions 1) the al-si alloy produced by squeeze casting has refined microstructure and a density close to the theoretical one. 2) the y2o3/al-si composites and cr2o3/al-si composites produced by squeeze casting have more microstructure refinement, higher hardness and lower wear rate than the unreinforced alloy. 3) the density decreases slightly with increasing particle volume fraction for y2o3/al-si composites. 4) the density increases with increasing the volume fraction for cr2o3/al-si composites. 5. 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[13] meyers m.a., chawla k.k., “mechanical behavior of materials” prentice-hall, inc., usa, 1999, p. 644. [14] abtan n.s., “a study on squeeze casting parameters effects on improving the metallurgical and mechanical properties of aluminum alloys” ph.d. thesis, dept. of production engineering and metallurgy, university of technology, baghdad, iraq, 2007. [15] callister w.d.jr., “materials science and engineering, an introduction” fifth edition, john wiley & sons, inc., 2000, p. 136. [16] al-kaaby a.s.j., “preparation and characterization of cast aluminum matrix sic particulate composite” ph.d. thesis, department of production engineering and metallurgy, university of technology, baghdad, iraq, nov. 2000. [17] rooy e.l., “aluminum and aluminum alloys” asm metals handbook, casting, 9th edition, 4th printing, vol. 15, materials park, oh, 1998. [18] long s, beffort o., cayron c., bonjour c., “microstructure and mechanical properties of a high volume fraction sic particle reinforced alcu4mgag squeeze casting” mat. sci. eng., vol. a, 1999. التركيب المجهري وبعض الخصائص للمواد المتراكبة نوع الالمنيومسليكون المقواة بأوكسيد الايتريوم او أوكسيد الالومينا احمد علي موسى قسم هندسة الانتاج والمعادن/ الجامعة التكنولوجية الخلاصة تم دراسة تحضير مادة متراكبة ذات اساس من سبيكة الالمنيومسليكون مقواة بدقائق اوكسيد الكروم (الالمنيومسليكون/ اوكسيد الكروم ) و دقائق اوكسيد الايتريوم (الالمنيومسليكون/ اوكسيد الايتريوم ) بطريقة السباكة بالعصر المباشر. تم اضافة كسور حجمية مختلفة من دقائق اوكسيد الكروم3.1, 6.3 , 9.4, 12.5 vol %) ) وكذلك اضافة كسور حجمية مختلفة من اوكسيد الايتريوم(4, 8.1, 12.1, 16.1 vol %) . اجريت عملية خلط منصهر سبيكة الالمنيومسليكون/ اوكسيد الايتريوم او منصهر سبيكة الالمنيومسليكون/ اوكسيد الكروم باستخدام خلاط كهربائي وبسرعة 500 دورة /دقيقة . تم استعمال المتغيرات مثل ضغط العصر (53mpa)، درجة حرارة الصب (700˚c)، زمن الكبس (30sec.) وزمن التريث (5sec.). ودرجة حرارة القالب(200˚c ) .تم فحص البنية المجهرية للمواد المتراكبة ،الصلادة ومعدل البلى . اظهرت النتائج حصول تنعيم في البنية المجهرية في السبائك المقواة مقارنة مع السبيكة غير المقواة . كما اظهرت النتائج زيادة في الصلادة وانخفاض في معدل البلى في السبائك المقواة مقارنة مع السبيكة غير المقواة . � embed pbrush ��� page 60 _1150795730.unknown _1173207870 _1150795719.unknown ١ alkhwarizmi engineering journal design and analysis of new prosthetic foot. muhsin j. jweeg, phd ahamed a. al-beiruti ,phd kadhim k.al-kinani,msc mechanical engineering department mechanical engineering department mechanical engineering department (al-nahrain university) (university of technology) (university of al-mustansirya ) (received 31 july 2006 ; accepted 19december 2006) abstract: there is a variety of artificial foot designs variable for use with prosthetic legs . most of the design can be divided into two classes, articulated and non-articulated feet. one common non-articulated foot is the sach . the solid ankle cushion heel foot referred to as the sach foot has a rigid keel . one key or the key factor in designing a new prosthesis is in the analysis of a patients response . this view is the most important because if the foot does not provide functional , practical or cosmetically acceptable characteristics the patient will not feel comfortable with the prosthesis , therefore design and manufacturing a new foot is essential, this foot made from polyethylene, its different shape and characteristics the characteristics deemed important by patients in achieving natural gait motion include: dorsiflexion energy return fatigue test in this study, including all these characteristics test, design fatigue foot tester according to iso 10328 and design new foot .also, the testometric crosshead was modified to find dorsiflexion angle and energy return .the fatigue criteria for polymer was proposed, in mathematical solution. finally , the characteristics of sach foot was compared with new foot by mathematical solution and used visual basic program and experimental method by different tests. from these test that the new foot is better than sach foot for all test . keywords: prosthetics foot , fatigue, dorsiflexion ,energy return and sach foot . alkhwarizmi engineering journal vol. 3 , , no. 1, pp12 – 25, ( 2007) this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ muhsin j. jweeg, phd /al-khwarizmi engineering journal ,vol.3, no. 1 pp 12-25 (2007) ١٣ introduction: amputation of a lower limb is most commonly performed due to landmines or disease of the limb. the two most often performed amputation procedures are truncation of the femur bone above the knee (ak) and truncation of the tibia bone below the knee (bk). physical loss of the anatomy of the lower limb results in loss of gait function. in bk amputees this loss is due partly to the loss of the articulated ankle joint, the loss of the joints of the foot (including the metatarsal-phalange joints), and the loss of the muscles of the anterior and posterior compartments of the shank. the levels and classification of below the knee amputations are shown in figure(1-b ) .[ 1 ] bk prostheses, figure (1-a) are typically comprised of four major components these are: socket, pylon, foot prosthetic and couplings. the main purpose of a prosthetic foot, shank and socket is to provide a means of replacing the lost structure and function of the skeleton and muscles of the foot, ankle and shank. [ 2] there are different type of foot but the one of most commonly is called (sach foot) since it was developed in the early 1950`s by the university of california. the numerous investigation have analyses compared different type of prosthetic feet by means of mechanical testing , gait analysis , ground reaction force , energy return and fatigue test . the durability and fatigue characteristics of prosthetic foot are very important when deciding which type of prosthetic foot to prescribe for a particular patient . there for a number of studied have cycled prosthetic feet to assess their durability and wear a cyclic tester which mimics natural gait .[ 3 ] in 1975 daher[4]conducted an extensive investigation in which nine types of sach feet were subjected to cyclic testing to assess the durability of the materials and design of the foot unless breakdown occurred. wevers and durance[5] in 1987 also conducted dynamic testing on prosthetic sach feet, but they loaded the whole trans-tibia prostheses not the foot alone. a report by kabra et al [6] utilized a simple , low cost machine to fatigue the jaipur foot , similar to toh's device. francis j. trost [7] investigated by using different material that stored energy when compressed by the body during early stance phase. lehmann and colleagues within two separate reports[8], [9], conducted a similar analysis determining the load vs. deflection (compliance) of prosthetic feet via a static loading machine. the new design foot: there are numerous prosthetic foot designs available these prosthetics feet serve basic functions which include: support the body against gravity during standing and walking ; this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ muhsin j. jweeg, phd /al-khwarizmi engineering journal ,vol.3, no. 1 pp 12-25 (2007) ١٤ absorb shock during heel contact and in some cases mimic metatar sophangeal function during the stance phase of gait , preventing the fatigue failure , principle of storing energy as the stance limb accepts body weight and returning this energy as the foot lift off the ground and good lifts off the ground and good dorsiflexion and eversion .the shape of new foot dependent to dorsiflexion angle and the energy return . the new design in consideration of the need of a lighter foot for the elderly amputee population and its relative low cost. the shape at point r of the foot ankle complex creates a joint with an axis of rotation that changes location during the stance phase as the body's center of mass proceeds forward over the foot figure(1-a) . the shaped ankle joint can be described c curve and shaped of end keel can be described also c curve . at the end of mid stance c curves closed and touch the top of the forefoot section . the new design foot is made of a flexible material (polyethylene )this allow the forefoot of the prosthetic foot to bend and the fatigue limit of this material was good. it is possible to design a simple , practical foot that achieves very specific performance criteria. currently , the cause of failure of most prosthetic feet used in developing countries is the breakdown of the prosthetic keel due to excessive wear of the cosmetic covering for the foot, usable with or without a cosmetic cover, the life of a foot is increased . the new foot is tested and checked all properties " dorsi-flexion, and fatigue failure" experimentally in the result section, in this study must be check analytically by used fatigue criteria. the shape of new design foot is difficult to be achieved foot properties or to mimic normal foot by size and comfortable. to find the life of new foot by proposed a new fatigue criterion for polymer: bc f ns 10 (general equation) blogncslog f )( ….(1) b is represented slope of equation (2) )( 1 1 2 1 )( n n log e f s s logb  ….(2) where n1 , n2,sf1 and se are no of cycle at high fatigue strength , no of cycle at low fatigue strength , high fatigue strength and low fatigue strength shown in figure ( 5 ),c is constant equation(2 )at n1. 2 1 1 2 1 2 1 n n log logn n n log logn ef logslogsc                     2 1 1 2 1 2 1 n n log logn n n log logn ef sslogc ..(3) b c a ln 1 10         this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ muhsin j. jweeg, phd /al-khwarizmi engineering journal ,vol.3, no. 1 pp 12-25 (2007) ١٥ ) 1 ( ) 2 1( 2 1 1 2 1 2 )( 1 es fs log n n log n n log logn n n log logn ef a l ss n                         ) 1 ( 1 1 2 ) 2 1( 1 es fs log logn lognn n log e fa l s s n                 ) 1 ( 1 2 )1 )()( 1 es fs log lognlogn a f e a l s s n            .(4) ffedcbae skkkkkks  ..(5) where ka , kb , kc, kd, ke are factors of : surface, size , reliability , temperature , modifying stress concentration and miscellaneous respectively, [ 10 ] : 1 fdca kkkk              mmdmmd mmd kb 2508189.1 81 097.0 ..(6) when a noncircular section such as a rectangular section: 2 1 )(808.0 hbd  )1(1  tf kqk f e k k 1  ……(7) where: ke is modifying factor for stress concentration, kf is fatigue stress concentration factor, q is notch sensitivity and kt is stress concentration factor. the stress at point t : 2 11max 6 ba lp  0min  2 11minmax1 3 2 ba lp a     …(8) the stress at point r : 2 211max 6 bc lp bc p  2 322min 6 bc lp bc p  2 322 2 211 2 3 2 3 2 bc lp bc p bc lp bc p a  2 322 2 211 2 3 2 3 2 bc lp bc p bc lp bc p a  …(9) ) 1 ( 1 2 )( )1 )(int 1 11 ets fs log lognslogn s tpoatn a f et a l              ) 1 ( 1 2 )( )1 )(int 2 12 ers fs log lognslogn s rpoatn a f er a l              (10) where set, ser are fatigue limit at t point and point r respectively. comparing between nlt and nlr then choose minimum number of cycle . these equations are used to build the visual basic program , the windows of program as shown in figure ( 5 ) this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ muhsin j. jweeg, phd /al-khwarizmi engineering journal ,vol.3, no. 1 pp 12-25 (2007) ١٦ experimental work: many experimental tests are recommended to the manufacture and design the foot. the tests were compared with the theoretical procedure to show the difference between the experimental and theoretical results. 1tensile test and fatigue test for polyethylene. 2design and manufacturing fatigue foot tester. 3design and manufacturing new foot. 4dorsiflexion, energy return and fatigue foot test to be achieved. tensile test and s-n curve test: the theoretical and experimental calculations depend on the mechanical properties of the material these can be found from the tensile test of standard specimens according to the recommendation of astm d-638.[11] the fatigue test (s-n curve ) for polyethylene according to astm d 671-[12] design and manufacturing of the fatigue foot tester (fft): the fatigue foot tester, figure (2 ), was designed and built using the functional requirements outlined in iso standards . according to iso 10328[13] standards , forces must be applied at 15o and anterior to tibia axis upon heel strike and 20 o posterior to the tibia axis upon toe off . the fatigue tester is designed to simulate human gait by alternating the heel and toe loadings. mechanical and electrical component for ( fft): each cycle test station consists of : 1pair of pneumatic cylinders (70.3 mm )bore , 90.2 mm stroke , single acting . 2a prosthetic foot – shank assembly . 3support brackets for the shank . 4counter to record the number of test cycles completed . 5all of the components mentioned above mounted onto frame. 6air compressor (120 l) with regulator. 7air filter (air mixture filter ). 8timer (to increase or decrease frequency of cycle) 9pair of solenoid valve . 10control system , gives alternative signal to the solenoid valve . the value of applied load according to iso 10328 for amputee 60 kg , that mean the ground reaction force about 753 n . in order to find a specific force value , various combinations of compressor pressure can be determined form : pdf bore 2)( 4   … (11) where f is the desired force , dbore is the diameter of the bore . a calibration table , comprising the desired force values for the various combinations can be process by use load cell and reader. design and manufacturing of new foot: in iraq and most of country, the sach foot is common foot but this foot had small dorsiflexion from ankle , it's depended to the end of forefoot bending , therefore its discomfort able. from forty state of foot failure in baghdad centre of artificial limb for sach foot is appeared the failure region midway between the head of metatarsals and the distal end of the phalanges that region is end of keel and it's applied the alternative load. its failure by fatigue. the sach foot in iraq it's from different company such as germany's foot (atto bock company ) and french's foot, there are no one design or manufactured this foot or any foot in iraq. disposal of the disadvantage for sach foot , by designing and manufacturing new design foot, it's depended on dorsiflexion and mechanical properties for material and prevent fatigue failure. the new foot design is made from polyethylene , that material is high endurance limit and good flexibility respect of the applied load according to the gap above keel and ankle .the heel region and base is manufactured by rubber foam . this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ muhsin j. jweeg, phd /al-khwarizmi engineering journal ,vol.3, no. 1 pp 12-25 (2007) ١٧ the new foot testing : a-fatigue foot test the sach foot is placed on fatigue tester to obtained life of foot .this procedure was applied to new foot to comparing between two life . the load is alternative as simulate normal gait , the first piston struck heel foot and second piston struck forefoot were sequenced. a counter in fatigue foot tester is recorded the number of strike. to control on frequency of strike by used frequency meter as according to iso standard bdorsiflexion test: to complete the dorsiflexion test must be manufacturing the triangular wood and supported with ruler graded [14].this piece of wood is put in testometric machine. it's replaced under crosshead. the foot is touched the triangle wood and applied force , this force simulated ground reaction force . dorsiflexion test is applied in two different of foot , sach foot and new design foot and comparison with normal human foot , figure ( 4 ). the amount of dorsiflexion as related to vertical displacement is therefore determined by the toe lever of the foot , where the toe lever is distance the attached pylon to pivot corresponding to the ball of the foot. x y1tan  … (12) cstored energy returned in this part compares the mechanical capabilities for storage and release of energy of sach foot and new design foot by examining their force –deflection characteristics, under certain given conditions. the energy stored and released could be express as an efficiency when compared to the ideal situation [15 ].energy storing potential can thus be defined in the following way[16] 100%  tarea parea potentialstoringenergy (13) area p: actual energy stored by material at limit. area t: ideal energy stored at force 753 n by recording the curve for loading and unloading , the hysterics loop for the material can be determined giving a percentage of energy returned . 100%  aarea barea efficiencyreturnenergy (14 ) the stored energy returned is relevant only to the value of load ( 60) kg and dorsiflexion (5o ) as it is dependent on the energy storing potential at these condition . 100 efficiencyreturnenergy potentialstoringenergyreturnedenergystored  (15) the results and discussions: theoretical results for new foot: from fatigue equations, we obtain the life of new foot , the life of new foot is 675387 cycle when a= 37 , b=75 , c =31 , sf1= 18.1 mpa , sf2=4.7 mpa , n1= 407 cycles and n2=10000000 cycles this result is represented by the visual basic program , figure ( 2 ) experimental results: the mechanical properties of all material and the fatigue test(s-n) curve for polyethylene are shown in table (1 )and table(2). the experimental results for foot are including: 1dorsiflexion and energy return: figure (6-a) and figure (6-b) show the results of the dorsi-flexion angle and energy storing potential respectively for sach foot and new foot. figure(7-a ) and figure(7-b) show the hysterics loop for the materials of foot. the dorsiflexion angle experimentally is obtained by video (camera ) then it’s plot with gait cycle . the maximum dorsiflexion angle at 75 % of stance phase a bout 5o , 1.8 o , 3.7o for this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ muhsin j. jweeg, phd /al-khwarizmi engineering journal ,vol.3, no. 1 pp 12-25 (2007) ١٨ normal human foot ,sach foot and new foot respectively. the stored energy return are 13.14 , 58.9 for sach foot and new foot respectively , table ( 3 ). from the shape of new foot explained two curve in ankle and keel end that help , in addition , the new foot was made from polyethylene that material was good for flexibility . 2fatigue foot tester results : in order to determine the validity of the new foot fatigue tester in comparison to other tester currently being used , the industry standard sach foot was tested in one of the test stations in order to determine its time failure . the sach foot that was deemed a failure at 112,786 cycles was stored for approximately 24 months prior to testing , however , the sach foot removed from the tester at 896,213 cycles was placed on the tester within a few months of manufacturing . this may indicate the material degradation in a factor in the life expectancy of sach feet, however, further testing would have to be under taken. the new foot failure occurred in one specimen at 1.233.417 cycles. the centre of curvature of beach marks indicate the origin of the failure and direct the investigator that served as crack nucleation sites . smaller location of crack propagation were evident however are believed to be secondary sources of failure. there are different value between theoretical results and experimental results for new foot because the fatigue criteria in polymer depend on application and the mathematical solution depend on assumption . conclusion: the new foot was easily the most suitable foot for the patient conditions chosen both in energy storing potential and energy return efficiency. the dorsiflexion angle for new foot better than sach foot . by comparing the characteristics exhibited by prosthetic foot to these of a human foot , a selection of these prostheses was undertaken based on their favorability to the characteristics of a human foot , the new foot is a good characteristics . the sach foot that was deemed a failure at less number of cycle when it was stored for approximately 24 months prior to testing . the new foot is a good life compared with sach foot. references 1.karl f. zabjek. analyse biome’canique des pieds sach et seattle-light durant la locomotion chez les personnes age’es amputees du member inferieur. msc thesis ,universite’ de sherbrooke , aout, 1997.pp 6. 2.ker r.. the time –dependent mechanical properties of the human subcalcaneal fat pad in compression, j anat . 1990 , 171: 131-38. 3.derek w. potter .gait analysis of a new low cost foot prosthetic for use in developing countries. msc thesis, queen's university at kingston canada , 2000. 3. daher r . physical response of sach feet under laboratory testing , bulletin of prosthetics research , 4-50, 1975. 4.wevers , h.w and durance , jp .dynamic testing of below knee prosthesis : assembly and components ., prosthetics and orthotics international , 11, 117-123, 1987. 5. kabra , s.g. and narayanan r. equipments and methods for laboratory testing of ankle-foot prostheses as exemplified by the jaipur foot , journal of rehabilitation research and development 28(3):23-34, 1991. 6. francis j. trost . energy –storing feet . journal of the association of children’s prosthetics – orthotics clinics , 1989, vol 24 , num 4, pp 82. 7. lehmann , j.f , price r. , boswell s.dralle and a. questad . comprehensive analysis of this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ muhsin j. jweeg, phd /al-khwarizmi engineering journal ,vol.3, no. 1 pp 12-25 (2007) ١٩ dynamic elastic response feet : seatle ankle/light foot versus sach foot , phys med rehabil 74:853 -861, 1993. 8. lehmann , j.f , price r. , boswell s.dralle and a. questad . comprehensive analysis of energy storing prosthetic feet:flex foot and seattle foot versus standard sach foot. phys med rehabil 74:1225 -1231, 1993. 9. joseph e. shigley. mechanical engineering design. library of congress cataloging in publication data, 1986 , pp 243. 10. astm standard test method for tensile properties of plastic d638-97 , astm standard 46-57 , 1998. 11. astm standard test method for fatigue of plastic d 671 , astm standard , 1998. 12. iso standard test method for fatigue foot test iso 10328 , 1996. 13. daniel rihs and ivan polizzi . prosthetics foot design . msc thesis , victoria university of technology , 2002 , pp 56. 14. ehara , y. , beppu m . , nomura , s. kunimi and takahashi s. energy storing property of socalled energy storing prosthetic feet . phys med rehabil 74: 68-72 , 1973. 15. b.contaya. energy storing prosthetic feet. monash university, rehab tech ,pp 73, 2001 this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ muhsin j. jweeg, phd /al-khwarizmi engineering journal ,vol.3, no. 1 pp 12-25 (2007) ٢٠ table ( 1 ) mechanial properties for polyethylen and rubber foam material σy (mpa) σult (mpa) e (gpa) polyethylen 16.52 22.3 1.23 rubber foam 5.3 8.2 0.58 table( 2 ) s-n data for polyethylen material sf1 (mpa) sf2 (mpa) n1 (cycle) n2 (cycle) polyethylen 17.16 3.82 407 10000000 table (3) dorsi-flexion and energy return name dorsiflexion angle energy storing potential% energy return efficicency% stored energy return % sach 1.9o 24.2 54.4 13.14 new foot 4.2o 73.4 80.3 58.9 table ( 4 ) life of different foot name life of foot (cycle) theoritically eperimentlly sach (old) 112,786 sach (new ) 896,213 new foot 752,342 1,233,417 this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ muhsin j. jweeg, phd /al-khwarizmi engineering journal ,vol.3, no. 1 pp 12-25 (2007) ٢١ a b figure ( 2 ) :anew foot , bsach foot figure ( 1) a-component of prosthetic bk, b –prostheses levels b a c point r point t keel (wood) socket shank (pylon) sach foot a b this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ muhsin j. jweeg, phd /al-khwarizmi engineering journal ,vol.3, no. 1 pp 12-25 (2007) ٢٢ figure(4) dorsiflexion and energy return : a-new foot , bsach foot a b sach foot regulator compressor cylinders solenoids counter figure( 3 ) fatigue foot tester this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ muhsin j. jweeg, phd /al-khwarizmi engineering journal ,vol.3, no. 1 pp 12-25 (2007) ٢٣ 0.00 1.00 2.00 3.00 4.00 5.00 dorsiflexion angle (degree) 100.00 300.00 500.00 700.00 0.00 200.00 400.00 600.00 800.00 l o a d (n ) 0.00 1.00 2.00 3.00 4.00 5.00 dorsiflexion angle (degree) 100.00 300.00 500.00 700.00 0.00 200.00 400.00 600.00 800.00 l o a d ( n ) figure( 6 ) load with dorsiflexion angle for : a – sach foot , bnew foot area p area t area p area t figure ( 5 ) visual basic program to find life and failure location of new foot this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ muhsin j. jweeg, phd /al-khwarizmi engineering journal ,vol.3, no. 1 pp 12-25 (2007) ٢٤this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ muhsin j. jweeg, phd /al-khwarizmi engineering journal ,vol.3, no. 1 pp 12-25 (2007) ٢٥ اطرافھم تصمیم و تحلیل قدم اصطناعي جدید للمبتورة كاظم كامل رسن احمد عبدالرحمن عبد الجبار . د .م.أ محسن جبر جویج. د.أ قسم ھندسة المكائن و المعدات قسم ھندسة المیكانیك قسم ھندسة المیكانیك الجامعة المستنصریة لوجیةوالجامعة التكن جامعة النھرین :الخالصة وغالبا ما تصنف تلك التصامیم . صطناعیة للمبتورة أطرافھم السفلى الألقدام الھناك تصامیم عدیدة تلك االنواع القدم الشائع الى نوعین منھا االقدام المحوریة التحرك و االقدام الثابتة المفصل و احدى وھو ثابت الكاحل یحتوي على و سادة في منطقة الكعب (sach) االستخدام و الذي یدعى بـ .مصنعة من رغوة المطاط اما الرسخ فیصنع من الخشب الصلب و یكون قصیرا ة حیث من تعتبر استجابة المبتور طرفھ من المفاتیح االساسیة في تصمیم االقدام االصطناعی المفروض ان یشعر المریض براحة تامة في استخدام القدم من ناحیة الشكل و االداء لذا صممنا قدم .جدید من مادة البولي اثلین تختلف من حیث الشكل و الخصائص عن القدم السابقة :مریض ان من اھم الخصائص التي یجب ان تتوفر في القدم و التي یمكن ان تضمن الحركة الطبیعة لل مقدرة القدم على االنحناء بصورة طبیعیة. طاقة االرجاع  مقاومتھا لفشل الكلل في ھذه الدراسة صممنا جھاز لفحص فشل القدم تحت حمل الكلل لمعرفة العمر التشیغلي الي قدم و كما قمنا بتصمیم طرف اصطناعي و اجرینا علیھ , iso 10328ذلك حسب المقیاس العالمي قیاس زاویة االنحناء للقدم و حساب طاقة االرجاع بعد ,حساب العمر التشیغیلي رات مختلفة منھااختبا –ان ابدلنا الفك السفلي لجھاز الشد و اجرینا اختبار الكلل لمادة البولي اثلیین الیجاد مخطط االجھاد .ریاضیا اوجدنا صیغة جدیدة لفشل الكلل في البولیمرات و من ثم تم بناء برنامج فیجوال بیسك , العمر كما اجرینا مقارنة ) sach(في النھایة اجرینا مقارنة بین خصائص القدم الجدیدة و القدم السابقة .ل المعاییر من القدم السابقةبین الجزء العملي و الجزء النظري و تبین ان القدم الجدیدة كانت افضل بك this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ finite element analysis of stresses in a welded pipe al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 5, no. 3, pp 1 15 (2009) the investigation of monitoring systems for smaw processes nabeel k. abid al-sahib* osamah f. abdulateef** ahmed samir hamza* * department of mechatronics engineering/ al-khwarizmi college of engineering/ university of baghdad email: dr_nabeelalsahab@hotmail.com ** department of manufacturing operation engineering / al-khwarizmi college of engineering/ university of baghdad email: ausamalanee@yahoo.com (received 10 february 2009; accepted 2 june 2009) abstract the monitoring weld quality is increasingly important because great financial savings are possible because of it, and this especially happens in manufacturing where defective welds lead to losses in production and necessitate time consuming and expensive repair. this research deals with the monitoring and controllability of the fusion arc welding process using artificial neural network (ann) model. the effect of weld parameters on the weld quality was studied by implementing the experimental results obtained from welding a non-galvanized steel plate astm bn 1323 of 6 mm thickness in different weld parameters (current, voltage, and travel speed) monitored by electronic systems that are followed by destructive (tensile and bending) and non-destructive (hardness on haz) tests to investigate the quality control on the weld specimens. the experimental results obtained are then processed through the ann model to control the welding process and predict the level of quality for different welding conditions. it has been deduced that the welding conditions (current, voltage, and travel speed) have a dominant factors that affect the weld quality and strength. also we found that for certain welding condition, there was an optimum weld travel speed to obtain an optimum weld quality. the system supports quality control procedures and welding productivity without doing more periodic destructive mechanical test to dozens of samples. keywords: artificial neural network, monitoring, fusion arc weld. 1. introduction a conventional welding system that depends on the welder's sensory perceptions: touch, sight, and hearing to evaluate the weld quality and on the welder's experience to make corrections is labor-intensive and frequently unreliable. if weld defects are detected from post weld inspection, the defective parts may result in unnecessary manufacturing cost and wasted man-hours to repair them. to solve this problem, the welding system must have in-process monitor and control of the process variables that mostly influence the weld quality [1]. the task of a weld monitoring system is to use captured signals to classify a weld into defective or nondefective groups. the signals of the welding process such as welding voltage and current can be used as variables. however, external sensors are expensive and restrict the mobility and flexibility of some automated arc welding systems. by comparison, welding voltage and current are inherent process parameters and are easy to measure. moreover, their curves reflect many peculiarities of the welding process in their shape. each kind of arc welding process is characterized by certain shapes of the welding voltage and the current typical for the process. any disturbances or occurrences of faults during welding inevitably result in variation of these curves to some extent [2]. therefore, quality assurance in arc welding may be achieved through examining welding voltage and current. because the arc welding process involves melting and resolidification of the base material, the geometry of the resulting weld head is a good indicator of the integrity of the weld. therefore, the geometry of the weld head: bead width, bead height, and penetration depth, along with the absence of spatter, is used as a quality indicator. even though mailto:dr_nabeelalsahab@hotmail.com nabeel k. abid al-sahib al-khwarizmi engineering journal, vol. 5, no. 3, pp 1-15 (2009) 2 these measurements are used to monitor the weld pool sizes with reasonable accuracy, it is difficult to conventionally locate a sensor on the weld and to simultaneously measure the bead width, depth of penetration and dispersion of spatter [1]. weld voltage and current comprise the basic welding electrical parameters. all other electrical parameters such as resistance and power are calculated from these two parameters. common measurement techniques include: peak value, root-mean-square (rms), average, and time integration. peak value measurements are more sensitive to potential changes in the welding process and noise spikes. rms, average, and integration measurements filter out the noise spikes, but may mask potential weld quality information [3]. many researches have been carried out on the welding quality and monitoring. the on-line quality monitoring technique was described to detect susceptibility of welding defect formation by using real time monitoring of welding parameters: arc voltage, work angle and traveling angle smaw (shielded metal arc welding process) was selected in this study [4]. the on-line quality monitoring system based on data mining (db) technology was established, the system was set up with client/server architecture [5]. a new approach for real-time weld quality monitoring was proposed based on the combination of optical sensors with fuzzy logic classification algorithms. the sensing hardware encompassed a/d converters and photodiodes measuring the radiations emitted by the plasma surrounding the welding arc. the measured data was then filtered and processed to determine in real-time indices of local quality of the welding process. these indices were then fed to a fuzzy system, which provides an index of the overall quality of the weld, classifying type and position of specific events (e.g. anomalies in the current, voltage or speed of the arc, contamination with other materials, holes) [6]. an efficient approach was presented to identify the stability and quality of short-circuit gas metal arc welding (gmaw) by using power spectral analysis and timefrequency spectral analysis methods. a systematic analysis based on experimental data showed that the short circuiting frequency is a determining factor on weld process stability. the relationship between the short-circuiting frequency and the process stability was established [7]. the theory of stochastic processes was applied to the analysis of gas metal arc welding data. a theoretical approach is presented and some of the commonly assumed hypothesis of process stationarity and ergodicity are verified for the data collected from stable processes adjusted for short circuiting and spray modes of metal transfer [8]. 2. monitoring of fusion arc welding monitoring fusion arc welds is becoming more important as humans are becoming more-andmore remote from the actual welding operation. many new systems are being developed to monitor automated or non-automated welding processes in real-time (on-line) or off-line. in general, monitoring methods can be divided into two classes: model based methods and feature based methods. model – based methods have two significant limitations. first, many processes are non – linear time variant systems; this makes them difficult to model, and secondl, the signals obtained from sensors are dependent on a number of other factors. feature –based monitoring methods use suitable features of sensor signal to identify the process conditions. these features could be derived from the current and voltage or from speed welding conditions [9]. for the purpose of increasing evidence that the precision of diagnosis and the fact that the process under way is correct, a number of welding samples that undergo a destructive testing (bending and tensile test) and non destructive test (hardness test) have been selected. selection of appropriate neural network technique will be a new and effective measure added to the above-mentioned steps to obtain an intact diagnosis of the quality status. in the area of shield-metal arc welding (smaw) techniques, process monitoring and defect-detection methods play a fundamental role in improving the quality and the result at reduced manufacturing costs. the invention provides an arc welding monitoring device by which it is possible to find easily how to detect data such as a welding current and a welding voltage that correspond to the speed of the electrode filler. in monitoring arc welding, an arc welding monitoring device is disclosed. this device comprises a means for detecting a welding current or an arc voltage, and a/d converter for converting analog output of detecting means to digital signals in terms of a sampling frequency, a means for setting an operator period and fluctuation pitch to obtain a fluctuation mean, a means for setting a monitoring value to monitor the fluctuation mean value of the welding current or arc voltage, a means for judging welding conditions or welding results by comparing the fluctuation means value of the welding current or arc voltage with monitoring values, and a means nabeel k. abid al-sahib al-khwarizmi engineering journal, vol. 5, no. 3, pp 1-15 (2009) 3 for displaying and outputting the judgment result of the judging means. recent successes in employing artificial neural network models, an artificial neural network (ann) is a mathematical model or computational model based on biological neural networks. it consists of an interconnected group of artificial neurons and processes information using a connectionist approach to computation. in most cases an ann is an adaptive system that changes its structure in accordance with external or internal information that flows through the network during the learning phase [10]. 3. experimental work experimental work was carried out according to a plan developed to monitor and control fusion arc welding process, as shown in figure (1). it begins by performing a welding process monitored by an electronic system followed by destructive and non-destructive tests to investigate quality control on welded specimens. the obtained data are then processed through the use of neural network model designed to control the arc welding process. several equipments were used to accomplish the experiments and tests of the present work see figure (2): 1. current sensor. 2. voltage transformer and amplifier. 3. multi channels digital storage oscilloscope. 4. otc ac arc welder – kr 300 shielded metal arc welding machine. 5. personal computer (pc). 6. tensile instrument and tensile test assembly. 7. bending instrument and bending test assembly. 8. hardness instrument and hardness test assembly. fig.1. smaw and quality monitoring and control (experimental plane) fig.2. diagram of arc welding and monitoring components welding machine otc ac-kr300 current sensor msq-60 voltage transformer wideband frequency amplifier current wave form and value personal computer digital storage oscilloscope nabeel k. abid al-sahib al-khwarizmi engineering journal, vol. 5, no. 3, pp 1-15 (2009) 4 4. experimental setup and operations the details of experimental set up, instrumentation and the procedure of working operation are listed below: 1select a non–galvanized steel sheet astm bn1323 with 6mm thickness with mechanical properties shown in table (1). we fixed the sheet by a suitable device in a horizontal level, prior to the welding process. 2clean the joint area where the welding will be done between the two metals to remove any surface contaminants. 3 select a suitable electrode wire type iso 2560/e 430 with diameter of 4 mm; the electrode should be positioned in a perpendicular position to the work piece with 30 degrees between it and the work piece at travel direction. 4select different welding conditions for each case (current, voltage, and travel speed) as shown in table (2). 5the ac power voltage supplied for the machine must be uniform. 6the welding type is square butt joint as shown in figure (3). 7the work piece must be cooled naturally after welding. 8meanwhile, during each welding cycle, the welding current form displays on a computer or on an oscilloscope. this behavior of current related to welding process will present the relation with the weld quality. 9destructive (tensile and bending test) and non-destructive (hardness) tests were performed to check weldment durability and strength. force is applied to the specimens by hydraulic system. while applying the force, the operator continues watching force and strain scales until failure occurs. at this moment, the reading should be immediately recorded. table 1, mechanical properties for the base metal represented in mechanical tests mechanical test type hardness test hv tensile strength n/m2 bending stress n/m2 mechanical test value 122 27.916 749.57 table 2, practical work condition weld no. voltage range setting (volt) current range setting (ampere) welding travel speed (mm/sec.) 1 30 100 5.19 2 45 150 4.53 3 60 200 5.93 4 75 250 7.16 5 90 300 10.52 6 30 100 2.66 7 45 150 1.94 8 60 200 2.98 9 75 250 2.04 nabeel k. abid al-sahib al-khwarizmi engineering journal, vol. 5, no. 3, pp 1-15 (2009) 5 fig.3. square butt joint 5. smaw monitoring using neural network to develop a neural-network model, the input and the output parameters of the component should be identified in order to generate and preprocess data, and then use the data to carry out ann training. for the purpose of performing reliable processing on the results obtained in this research, a neural network has been established to develop ann model utilizing quality parameters (welding tensile strength, welding bending strength, and hardness of haz). the first step toward developing a neural model is the identification of inputs and outputs. determination of output parameters are based on the purpose of the neural-network model. the input output variables, number of nodes and activation functions are shown in figure (4), in which the input variables are welding voltage, welding current and welding travel speed, therefore a number of input nodes is set to 3. output variables are welding tensile strength, welding bending strength and hardness. therefore a number of output nodes is set to 3. there are two hidden layers and the number of nodes is set to 5 and 3. log-sigmoid is used as activation function for hidden layer no.1 and 2 and as a pure line function for output layer. levenberg marquardt (lm) is used as a training method, where ten experimental sets are taken as training data. eventually, ann programs are created by matlab (v7). fig.4. developed ann model utilizing quality parameters (current, voltage, and travel speed). nabeel k. abid al-sahib al-khwarizmi engineering journal, vol. 5, no. 3, pp 1-15 (2009) 6 6. results and discussions the experimental work on welding showned several practical variables and it gave clear indications for welding quality precept and resulting mechanical properties. these variables are: tensile test readings obtained at failure, bending test readings obtained at failure, and hardness test reading obtained at heat effected zone. quality monitors and control processes have been implemented by adopting variable welding conditions in order to know the result of changing these conditions on weld quality. welding conditions include: voltage range setting, current range setting, and welding travel speed. figures (5) to (10) show the relationhip between weld current and mechanical properties of a welded sheet (tensile strength, bending stress, and hardness of the heat affected area) at two different average travel speed of 7.704 mm/sec. and 2.405 mm/sec. these curves showed clearly the recommended current point for its conditions. we can show that the rates of welding quality parameter in general increase with the increase of voltage and current to a certain limit after that the increase in voltage and current causes a decrease of welding quality parameter because of the high temperature produced in the welding process that causes the melting of the work piece partially or completely at the joint line. this case is used normally in cutting material using welding machine. after verifications, it was noticed that the main reason for strength decline in tensile and bending test values is due to the variations in welding conditions. hence, for the purpose of achieving acceptable levels of quality, it is recommended to check and diagnose the negative effects in each welding process and then modify the welding terms accordingly. thus, it is observed that there is a relationship between the monitored current values and the welding conditions, which showed a clear advantage of the current monitor. fig.5. effect of weld current on tensile strength at weld travel speed (7.704 mm/sec) fig.6. effect of weld current on tensile strength at weld travel speed (2.405 mm/sec) case 1tensile strength and current 0 5 10 15 20 25 30 35 0 50 100 150 200 250 300 350 current (amp.) t e n s il e s tr e n g th ( n /m 2 ) case 2 tensile strength and current 0 5 10 15 20 25 30 35 40 0 50 100 150 200 250 300 current (amp.) t en si le s tr en g th ( n /m 2) nabeel k. abid al-sahib al-khwarizmi engineering journal, vol. 5, no. 3, pp 1-15 (2009) 7 fig.7. effect of weld current on bending stress at weld travel speed (7.704 mm/sec) fig.8. effect of weld current on bending stress at weld travel speed (2.405 mm/sec) fig.9. effect of weld current on hardness of haz at weld travel speed (7.704 mm/sec) fig.10. effect of weld current on hardness of haz at weld travel speed (2.405 mm/sec) case 1 bending strength and current 0 100 200 300 400 500 600 700 800 0 50 100 150 200 250 300 350 current (amp.) b en d in g s tr en g th ( n /m 2) case 2 bending strength and current 0 200 400 600 800 1000 1200 1400 0 50 100 150 200 250 300 current(amp.) b e n d in g s tr e n g th (n /m 2 ) case 1 hardness and current 235 240 245 250 255 260 0 50 100 150 200 250 300 350 current (amp.) h a rd n e s s ( h v ) case 2 hardness and current 0 50 100 150 200 250 300 350 0 50 100 150 200 250 300 current (amp.) h a rd n e s s ( h v ) nabeel k. abid al-sahib al-khwarizmi engineering journal, vol. 5, no. 3, pp 1-15 (2009) 8 welding operations showed that changing the setting of the current range on the welding machine did not necessarily indicate the precise value of the current, which was concretely consumed during the implementation of the welding operation. the current monitor can do this task instead of the welding machine and precisely detect and display the welding current value. here, it is important to mention that the welding current value is falling as a key factor in determining the welding quality. figures (11)-(16) show the monitoring instantaneous current oscillation with a sample of welding at different welding conditions. we can see that the amplitude of welding current is varying in ripple form that is caused by an unsteady state condition of welding like the distance between electrode and work piece surface, cleaning of surface and its effect on conductivity, the length of the electrode that is reduced in welding process and any change in the speed and the direction of the electrode or the electrode feed. all of these caused this ripple in the current and then had an effect on the welding quality. weld direction fig.11. instantaneous current value in welding (i= 100 amp, v=30 volt, vw= 5.19 mm/sec) weld direction fig.12. instantaneous current value in welding (i= 100 amp, v=30 volt, vw= 2.66 mm/sec) nabeel k. abid al-sahib al-khwarizmi engineering journal, vol. 5, no. 3, pp 1-15 (2009) 9 weld direction fig.13. instantaneous current value in welding (i= 150 amp, v=45 volt, vw= 4.53 mm/sec) weld direction fig.14. instantaneous current value in welding (i= 150 amp, v=45 volt, vw= 1.94 mm/sec) nabeel k. abid al-sahib al-khwarizmi engineering journal, vol. 5, no. 3, pp 1-15 (2009) 10 weld direction fig.15. instantaneous current value in welding (i= 250 amp, v=75 volt, vw= 7.17 mm/sec) weld direction fig.16. instantaneous current value in welding (i= 250 amp, v=75 volt, vw= 2.04 mm/sec) to investigate that the monitoring current represented a good indication of the weld quality, we made an artificial failure prior welding process by making a holes in a joint line between two plates or introducing intermetallic components, inclusions, or thermal stresses in the joint line and then welding the joint. we noticed a great change in the current ripple values at these failure regions as shown in figures (17) and (18). nabeel k. abid al-sahib al-khwarizmi engineering journal, vol. 5, no. 3, pp 1-15 (2009) 11 weld direction fig.17. monitoring defect in welding (vacancy) weld direction fig.18. monitoring defect in welding (hard particle) ann was developed utilizing quality parameter (welding voltage – welding current – welding travel speed). making use of experimental result data (tensile strength, bending stress and hardness of haz) has trained a neural network for a process model, which can predict nabeel k. abid al-sahib al-khwarizmi engineering journal, vol. 5, no. 3, pp 1-15 (2009) 12 the level of quality for different welding conditions as shown in tables (3) and (4). the training curve of the network is shown in figure (19). running the network gives an important advantage showing its ability to predict additional readings of quality parameter besides the original ones obtained from the experimental work upon inserting new interface values of welding conditions taken within the employed ranges. it will be noticed that the network also predicts new interface reading of quality parameter (tensile and bending test value and finding the effect of heat at hardness of haz) approaching the values to those obtained from the experimental runs. welding conditions and quality parameters are the name of the neural networks which have been trained to a set of data derived from the practical experimental runs, that makes the networks ready to receive new data for subsequent prediction. new data should be accordingly set as input parameters, which represent only the welding conditions within the limits adopted in this study. consequent outputs are new rates that represent only quality parameters which are predicted by the pre-trained neural networks. it is clear that agreement of the total values and convergence readings of each set shows that the trained neural networks are ready to predict quality parameters whenever it is required. some network results were found far from reasonable values due to inadequate neural network training data, because of the limited number of samples and need for modern instrument to reduce the time of testing samples. table 3, ann 1 output utilizing quality parameters (tensile and bending strength test value at failure – hardening effect value) input no. voltage setting (volt) current setting (amp.) speed of welding (mm/sec) hardness of haz (hv) tensile strength (n/m 2 ) bending strength (n/m 2 ) 1 30.0000 100.0000 4.5 242.9536 9.1614 290.9129 2 36.6667 122.2222 5.2 244.4841 9.7385 309.1162 3 43.3333 144.4444 5.8 246.0196 10.2963 327.3195 4 50.0000 166.6667 6.5 247.5610 10.8632 345.5228 5 56.6667 188.8889 7.2 249.1835 11.4391 363.7261 6 63.3333 211.1111 7.8 250.6260 11.9861 381.9294 7 70.0000 233.3333 8.5 252.1486 12.5631 400.1327 8 76.6667 255.5556 9.2 253.6709 13.1289 418.3360 9 83.3333 277.7778 9.8 255.2154 13.6979 436.5393 10 90.0000 300.0000 10.5 256.7459 14.2638 454.7426 table 4, ann 2 output utilizing quality parameters (tensile and bending strength test value at failure – hardening effect value) input no. voltage setting (volt) current setting (amp.) speed of welding (mm/sec) harness of haz (hv) tensile strength (n/m 2 ) bending strength (n/m 2 ) 1 30 100.0000 1.9400 235.7538 28.9437 991.6251 2 35 116.6667 2.0556 245.2694 29.3566 1008.1322 3 40 133.3333 2.1711 254.7849 29.7835 1025.2635 4 45 150.0000 2.2867 264.3005 30.1904 1042.7693 5 50 166.6667 2.4022 273.8161 30.5743 1060.2431 6 55 183.3333 2.5178 283.3316 31.0122 1077.4627 7 60 200.0000 2.6333 292.8472 31.4281 1094.2719 8 65 216.6667 2.7489 296.6070 32.3700 1081.7679 9 70 233.3333 2.8644 302.3667 33.7220 1069.2363 10 75 250.0000 2.9800 310.1265 34.8539 1056.6638 nabeel k. abid al-sahib al-khwarizmi engineering journal, vol. 5, no. 3, pp 1-15 (2009) 13 fig.19. ann training curve utilizing quality parameters for case 1 7. conclusions the main conclusions of this research in the field of smaw quality and online current monitor system are as follows:  the system has high response sensing capability which is needed to meet the requirements of smaw monitoring process which can be installed directly to the welding machine and then to a computer without leaving a negative impact on the efficiency of the machine or causing a technical obstacle that prevents the operator from performing his duty well.  it provides the operator with an opportunity to watch and monitor the welding current value for each welding trial individually from a distance no less than 5 meters.  record the current form at all welding processes and save it as image on the computer that perform the welding quality. this can be a certificate of the welding process.  the system supports quality control procedures and welding productivity without the need to stop the production sequence or doing more periodic destructive mechanical testing to dozens of samples. here, it can be noted which economical gains could be achieved in utilizing such electronic surveillance feature.  reduce the probability of welding failure and decide the weakness points and layers after checking the current response and delimitation of the defect region to be tested.  the optimum parameters achieved (for welding 6mm thickness of non-galvanized steel plate astm bn 1323 type and for welding a square butt joint using 4mm electrode diameter of iso 2560/e 430 type) are 150 ampere and 45 volt with 0.24 cm/sec for welding travel speed.  ann was a useful technique to predict the level of quality for different welding conditions utilizing quality parameter (voltage, current, travel speed) using experimental result data (tensile strength, bending stress, and hardness of haz). this ann could predict any welding quality parameter for any welding condition within the range of previous input value. 8. references [1] rong ho (ron) lin & gary w. fischer, "an on-line arc welding quality monitor and process control system", 1994, proceedings nabeel k. abid al-sahib al-khwarizmi engineering journal, vol. 5, no. 3, pp 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[2] c. s. wu, t. polet & d. rehfeldt, "a fuzzy logic system for process monitoring and quality evaluation in gmaw", 2001,sponsored by the american welding society and the welding research council. welding journal 33-s to 38-s. [3] hallowell avenue arcadia, "weld monitoring primer for microresistance welding – update", 2005, microjoining solutions – microtips™ 5563, ca 91007. [4] rittichai phounium & bovornchok poopat, "on-line quality monitoring of welding defect susceptibility in smaw", 2001, by king mongkut's university of technology thonburi, bankok. [5] chun-hua zhang, li di, zeng an, "welding quality monitoring and management system based on data mining technology", 2003, proceedings of the second international conference on machine learning and cybernetics 0-7803-7865-2/03/ 17.00 2003 ieee, pp 13-17. [6] a. g. glover, j. t. mcgrath, m. j. tinkler & g. c. weatherly, "the influence of cooling rate and composition on weld metal microstructure in c-mn & hsla steels", 1977, welding journal, pp. 267s 273s. [7] g. m. evans, "effect of manganese on microstructure and properties of all weld metal deposits", 1980, welding journal, pp. 67s 75s. [8] m. zhou, h. zhang, & s. j. hu., "relationships between quality and attributes of spot welds", 2003, sponsored by the american welding society and the welding research council, welding journal, 72-s to 77-s. [9] sadek c.a. alfaro, diogo de s. mendonca and marcelo s. matos, "emission spectrometry evaluation in arc welding monitoring system"2006, published by elsevier science ltd. journal of materials processing technology, vol. 179, (2006) pp. 219 – 224. [10] aimen mohammed ahmed bachaa, "wear monitoring in turning processes using vibration and strain measurements", 2005, msc thesis mechanical engineering – baghdad university. 15 -1، صفحة 3، العذد 5هجلة الخىارزهي الهنذسية الوجلذ نبيل كاظن عبذ الصاحب (200 9) 15 األستقصاء عن أنظوة الوراقبة و السيطــــره على عوليات اللحـــام بالقىس الكهربائي * أحوذ سوير حسين** أساهة فاضل عبذ اللطيف*نبيل كاظن عبذ الصاحب صايؼت بغذاد / ُْذعت انخٕاسصيٙالكهٛت / قغى ُْذعت انًٛكاحشَٔٛكظ* صايؼت بغذاد / ُْذعت انخٕاسصيٙالكهٛت / قغى ُْذعت ػًهٛاث انخصُٛغ** الخالصة ٌّ ٚزْب يغ انًؼٕٛوِ اٌ انهغاو عٛذػًهٛاث األَخاس انًانٛتَة ْٔزِ حَةْغذُد خصٕصاً فٙ االسباط ْا حضٚذ اعخًانٛتعاِو يًٓتُ صذاً ألٌللا ٔصٕدة َٕػٛتَة يشاقبت . كهفتٔقِج ٔالخغاسة فٙ الانخغائِش فٙ اإلَخاسِ َٔٚةغخهضُو يؼانضخّ ( ann) انخٙ حَةغخؼًُم شبكت ػصبٛتَة صطُاػٛتَة انكٓشبائٙقِٕط بال األَصٓاس٘وانظال ػًهِٛت فٙ ٔقابهِٛت انخغكى َٕػٛت انهغاو ْزا انبغِذ َٚةخؼايُم يغ يشاقبت . ًَٕرسك ٍْ نظػُاصش حأرٛش صٕل ػهٛٓا ِي -astm bn non 1323 ) انفٕالرِ صفٛغتوا انهغاِو ػهٗ َٕػِٛت انهغاوَة ُدِسطَة بخَةطبٛق ََةخائِشِ حضشٚبِٛت حى انغَة galvanized) رى حُبؼج بأخخباساث حًج انًشاقبت باألَظًِت اإلنكخشَِٔٛت، (نغاوِ ال ةحٛاس نغاِو، فٕنخٛت نغاِو، عشع) انهغاِو انًخخهفِت ظشٔف يهًٛخش فٙ 6 بغًك . نخَةغّش٘ يشاقبت انضٕدة ػهٗ ًَارسِ انهغاو (أخخباس انصالدة)ٔغٛشأحالفٛت نؼُٛاث أخشٖ (َْغُاءاإلنشّذ ٔا أخخباس ) نؼُٛاثأحالفٛتفغص ٌّ انَُةخائِشَة انخضشٚبٛتَة انًكخغبتَة ِٙ بأدخانٓا ل ْاػانضجوّو ث ة ػهٗ ػًهِٛت انهظةًَٕرسِ انشبكت انؼصبِٛت اإلصطُاػ ْٛطَةشَة و ا انهظظشٔفو ٔحٕقُّغ يغخٕٖ انُٕػِٛت لا نهغَة . انًخخهفتِ ٌّ ٌَة (انهغاوحٛاس، عشػت الفٕنخٛت، ال)و ا انهظظشٔف عخُُخِشَة بأ ا ِة انهغاوَة الػٕايم ال ثكَة ّٕ صذََةا . يًُٓٛت انخٙ أَةرّشْث ػهٗ َٕػِٛت ٔق َٔة اَّ ػُذ حغذٚذ ظشٔف أٚضاً . قصِٕٚت نهُغُصٕل ػهٗ َٕػٛتَة نغاِو قصٕٚتِ نغاو ُْاك عشػتُ ث، كاٌانهغاو م خخباس يٛكاَٛكٙ حذيٛش٘انظاَخاصٛت ال َٚةْذػُى انُظاُو صشاءاثَة يشاقبت انضٕدِة ٔ ًَة . انؼُٛاثِ يٍانؼششاثِ يٍ أكزِش انٗو بذٌٔ ػَة al-khwarizmi engineering journal al-khwarizmi engineering journal, vol.4 , no.1 , pp 4857 (2008 ) microcontroller-based function generator riyadh a.h. al-helali electrical engineering al-mustansiriyah university dr. ismail a. mohammed electrical engineering baghdad university ammar i. abdullah computer electrical ministry of work & social insurance (received ï ömay 2007 ; accepted 5 february 2008) abstract: this paper describes a microcontroller-based function generator system. by the function generator sine wave, square wave, quasi-square wave, saw-tooth and triangular waveforms are generated over a wide frequency range according to user requirements. by utilizing processing capabilities of the microcontroller the hardware is minimized exceedingly. the output waveform shapes are digitally-controlled to achieve the required wave shape. the single chip microcomputer of waveform generation equipment offers the possibility of improvements in manufacture reliability, maintenance and servicing and increased control flexibility. the system is built and tested. the results of test were satisfactory and appreciated by test engineers at different centers of ministry of communications. keywords: microcontrollers & microcomputers, programmable controllers, waveform generation. introduction: educational institutions and colleges as well as test engineers need a function generator that generates certain shapes of waveforms at a wide range of frequency. the potential and versatility of function generation techniques have not yet been fully realized, and in the past have been limited by the conventional hardwired an analogue and digital circuits which were available [1,2]. this complicates the circuit and increases the cost of the instrument. the operational advantage of the ml2036 (micro linear) [1] is only a sine wave generator capable of producing a sine wave signal with a frequency from dc to 50 khz and it only needs a few components but has limited frequency range, while the experimental circuit of the hsp45102 (programmable generator) [1] used the centronic experimental board. the control software [1] is written in turbo pascal 6, thus, the experimental circuit operation depends on the pc, which passes through languages translators via compilation process and assembly process. the control program that is fitted into the on-chip rom of the microcontrollerbased system deals with interrupts to generate the required function [2]. since the important feature of microcontrollers is the built-in interrupt system. a microcontroller-based system is numerically attractive since it offers increased flexibility, particularly in choosing the required frequency among a wide range of frequencies. these advantages inevitably result from a reduction in the complex control circuitry, which may be progressively replaced by microcontroller software. then it is possible to generate any frequency waveform is previously assigned without altering the hardware. to reduce the components and instrument cost a software-based system is to be designed and built. it is possible to proceed riyadh a.h. al-helali al-khwarizmi engineering journal, vol.4 , no. 1 pp 48-57 (2008) ñö !! directly and attempt to implement, design a microprocessor, one of the previously developed hardware analogue or discrete digital-control technique [3]. however, to take a full advantage of the shift in emphasis from hardware to software design, and make effective use of the computing power of the microprocessor, a new and more fundamental approach to system design is required. by building algorithms to generate the various waveforms and control programs the required waveform can be generated with a minimum number of components. reducing the components and adopting software increase the reliability of the system and flexibility of the system operation based technique [3,4]. real-time generation of digital waves the “real-time” generation of a digital wave using an 89c51-version microcontroller utilizes an algorithm that consists of many subroutines to produce the required waveform. therefore, each wave takes subroutine execution time which is different from that of another wave generation and depending on the usage of the instruction sets to form the right creation with exact time interval. the approach to be used for generating a periodic quasi-square wave on a certain output port of the microcontroller with the required frequency is to create intervals of various lengths for setting the output port in one hand and resetting it in the other hand. it is possible to create a quasi-square wave with variable duty cycles, thus, the software running the timer is the best choice to create time delays. the creation of a square wave used the same approach of a quasi-square, with a duty cycle of 50%. another approach for creating it by using time interrupts; with time interrupts enabled [4,5], the event that generates the interrupt is the setting of the timer flag upon overflow of the timer registers. the triangular wave can be generated using a software up/down counter, the rate at which this counter is incremented (or decremented) determines the frequency and accuracy of the generation process. it also can be achieved based upon either resetting the up/down counter at the start of each cycle or deriving the interrupt signal to the cpu from the up/down timers [3]. the saw-tooth wave algorithm is achieved by using software based on up/down counter that is incremented with a suitable step value for resetting the maximum values register to produce the required frequency. the “real-time” generation of a sine wave using a microcomputer algorithm is time consuming [3,4]. for example, a zilog z80 microprocessor with a 2.5 mhz clock takes about 800 s to calculate one sine value [3]. it is therefore inappropriate in high frequency applications to calculate the sine wave values, as they are required in “real-time”. an alternative approach is to store the sine values in a lookup table, which is preprogrammed into on-chip code memory (rom). alternatively, the sine values may be stored in external volatile memory (ram), the values having first been calculated by the microprocessor during the initialization period prior to generator startup. the memory requirement, efficiency of operation and accuracy of output waveform depends on the number of sample values defining a cycle of the sine wave and their resolution. if, for example, the values are taken at 05.0 intervals, then a complete sine wave cycle is defined by 720 values. the sine wave could be defined at a greater number of sample points, but the memory requirement is proportionally increased. the resolution of each lookup table value must be specified on the basis of the type of generation algorithm to be performed and the required accuracy of the width output values. for most applications, an 8-bits word length is sufficient and this is particularly appropriate if an 8-bit microprocessor used. the memory requirement is reduced if only one half or even a quarter of a complete sine cycle is stored in a lookup table [2]. in either case, the bit definition is increased by one since it is no longer necessary to indicate the sine of each sample value stored. the accessing of values from the lookup table may most easily be indicated using a pointer. if a complete generated sine wave cycle is stored in memory, then the riyadh a.h. al-helali al-khwarizmi engineering journal, vol.4 , no. 1 pp 48-57 (2008) òí !! pointer cycles the lookup table. a similar procedure may be followed if only half a cycle of the sine wave is stored [3]; although, in this case, it is necessary to include a flag to indicate whether the case value obtained is of positive or negative sign. this flag is also required if only a quarter of a cycle is stored. in this case, the pointer moves up and down the lookup table instead of in one direction. hardware-based system in this system, the microcontroller is only required to generate the variablefrequency digital waveforms. a typical system arrangement is illustrated in figure 1. the system consists of the following blocks: 1. 89c51 microcontroller. 2. hexadecimal keypad. 3. intelligent dot matrix alphanumeric display [6]. 4. digital–to–analogue converter (dac) [2,3,4]. 5. buffer stages to isolate the outputs. 6. amplifier stage. there are two modes of operation, which take two stages, and generate two groups of waveforms; group 1 includes generation of triangular, saw-tooth and sine waveforms, while square and quasi-square waveforms belong to group 2. interfaces to keypads are common for microcontroller-based designs, the keypad contains 16 keys, which are connected to interrupt control pins of the microcontroller. during each interrupt, the memory is accessed and takes variable time for each generated waveform. while the 2416 [6], is a four digit, 5*7 dot matrix intelligent alphanumeric led display modules complete with built-in cmos driving circuitry and it is connected to port 0 of the 89c51. each character in any memory location can be addressed independently and will continue to display the character last written until another one replaces it. interfacing the real world often requires generating or sensing analog conditions this design used two transistors, two capacitors, a potentiometer, an lm301 op amp. [5], which represents the amplifier stage and mc1408l8 [4], is an 8-bit digital-to-analog converter (dac). the eight data inputs to the dac are driven from port 1 on the 89c51. writing different values on port 1 and adjusting the 1k potentiometer, the output should vary from 0 volts (p1 = 00h) to about 10 volts (p1 = ffh). the input command information, which relates the wave shape and its required frequency, is entered through the keypad. by pressing the appropriate key, an interrupt signal is driven that executes the interrupt service routine (isr) algorithm, then the memory is accessed and output the required waveform. each key of the keypad corresponds to a certain (isr). there are (12) isrs carrying out the following functions: (i) defining the frequency. (ii) adjusting the display digits using (4) keys. (iii) selecting the right frequency page of the program using (2) keys. (iv) choosing the wave shape using one of (5) keys. the linear-mode operation that generates waveforms of group 1 through port 1 of the microcontroller to the digital-to-analogue converter then produces the analogue signal at low power level. the levels of voltage and current can be amplified by using an amplifier stage to get the required specifications. the switching-mode generation that generates waveforms of group 2 through one pin of port 4 of the microcontroller and it is also amplified using the same amplifier stage. an optocoupler is used as a buffer stage between the microcontroller and the power circuit [2]. software system it is important first to consider the time constraints imposed when “real-time” generation of the digital waveforms is attempted in the microcontroller software. the software generation of the waveforms has already been described the maximum frequency of the function generator. in order to assess the time constraints, on square and quasi-square wave, have one riyadh a.h. al-helali al-khwarizmi engineering journal, vol.4 , no. 1 pp 48-57 (2008) òî !! cycle taking minimum time typically is 4 s and maximum value, which is loaded in the timer registers. but for saw-tooth and triangular waveforms, assume that one cycle involves 256 (maximum) increments, 256 (maximum) decrements and 512 comparisons, each update taking typically 3 s . the sine wave is defined by 1024 (maximum) sample per cycle, each taking typically 15 s to be accessed from memory and loaded it to the microprocessor, for a z80 with a 2.5 mhz clock, the maximum frequency from the microprocessor is limited to approximately 12 hz [3]. to generate the time period in real time it is required that the time counter to be loaded with a value from the cpu corresponding to the required period for square and quasi-square. the rate of decrement of the counter for sawtooth and triangular waveforms is determined by its clock. when a zero value is reached, the counter output changes and generates an interrupt signal to inform the cpu that the time period has been completed. the cpu responds by loading the next period into the counter and changes the signal from the output port, hence the required waveform is generated. the software-based system consists of two algorithms, the main program and the interrupt service routine program. the main program initializes mode timers, interrupt registers and other general purpose registers while the interrupt service routine portioned into five subroutines, each one consists of a number of pages, which operates at a certain frequency band generation, that generate its waveform. the software algorithm has the following tasks: 1. main program, which executes the following, tasks: selecting the timer mode of operation.  enabling the external interrupt registers. assigning the external interrupt according to the connection of the keypad.  performing the do nothing loop statement waiting for pressing any key of the keypad. 2. interrupt service routine program (isr) which executes the following tasks:  scanning the row and column lines of the keypad to determine if a key is pressed.  calling a delay function subroutine to allow for a delay time between increment and decrement steps of the keys.  selecting the frequency band of generation.  displaying the frequency hexadecimal code on the display.  running the subroutine of waveform generation. the software interrupt routine is used for servicing the external interrupt shown in the flow diagram in figure 2, together with the main program function used to generate the waveforms. experimental results the experimental results presented in this section were obtained using an experimental microcontroller function generator system. an at 89c51-version microcontroller was used to provide the waveforms. the function generator implementation used is based on the microcontroller hardware configuration, which used a crystal oscillator of 12 mhz clock. all the experimental results are delivered from the analogue circuit using the software algorithm described in section 4. the experimental results have been chosen to illustrate some of the main features of microcontroller which have been discussed previously are shown in figure 3. the experimental study of these results, which is taken at a wide frequency band, shows the following specifications:  quasi-square wave includes:  rise time = 25 nsec.  fall time = 0.1 s . overshooting invisible as a single pipe.  ringing invisible. no sag. different duty cycles.  10 volt peak-to-peak, 0.3 ma output current.  frequency range from less than 1 micro hz to 250 khz. riyadh a.h. al-helali al-khwarizmi engineering journal, vol.4 , no. 1 pp 48-57 (2008) òï !!  square wave includes:  rise time = 10 nsec.  fall time = 5 nsec. neither overshooting nor ringing or sag.  10 volt peak-to-peak, 0.3 ma output current.  frequency range from less than 0.006 hz to 166.666 khz, larger that limits can be obtained by using the quasi-square wave with duty cycle of 0.5.  saw-tooth wave includes:  frequency range from (1 micro hz to 150 khz).  10 & 5 volt peak-to-peak, 0.3 ma output current. triangular wave includes:  frequency range from (1 micro hz to 166 khz).  10 & 5 volt peak-to-peak, 0.3 ma output current.  it can be generated from the saw-tooth algorithm with certain step such as 128.  sine wave includes:  frequency range from (1 micro hz to 100 khz).  10 volt peak-to-peak, 0.3 ma output current. from the experimental waveforms shown in figure 3, a quasi-square wave generated at 250 khz, square wave at 160 khz, saw-tooth at two frequencies; upper frequency at 125 khz and lower frequency at 50 khz, triangular wave at 150 khz and sine wave of upper frequency at 20 khz and lower frequency at 1200 hz with 512 lookup table samples. therefore, the flexibility of the microcontroller software enables as for generation waveforms continuously at wide frequency band. the correct generation of the frequency wave that corresponds the required signal specifications depends upon the approximate conversion of the decimal time interval to a negative hexadecimal code numbers and the flexibility of choosing the parameters of delay relations when using theoretical calculations. the frequency fluctuation can be minimized to a very small value by actuate theoretical calculations of the entered hexadecimal code frequency numbers through the keypad. the linear-mode waveforms suffer from amplitudes decreasing and small distortion when generated above the upper frequency. this is due to least number of steps used. the main limitation of the system is the upper frequency, which is limited by the chip version, the clock frequency of the crystal oscillator, the conversion time of the digital to analogue converter to produce the output signal. the upper frequency can be increased up to 1.25 mhz for switching-mode waveforms, and up to the range of (250 khz – 750 khz) for the linear-mode waveforms, by decreasing the machine cycle time of the 89c51 cpu to less than 1 s , which is used. by using a crystal oscillator of 40 mhz and fastest conversion time of the dac this value can be achieved. conclusion a microcontroller-based function generator is designed and built. the experimental results show that a waveform of acceptable accuracy could be obtained with a high degree of flexibility reduced generator riyadh a.h. al-helali al-khwarizmi engineering journal, vol.4 , no. 1 pp 48-57 (2008) òð !! size and a small number of components. the upper frequency range is limited by the switching frequency of the microcontroller. the fetch and execution time taken by the instruction pointer of the cpu are (1 s ) for each machine cycle, to execute the subprograms. it can be shared by dividing the program into equal fixed-size parts (i.e., each part has the same machine cycle), and to carry out the whole work by performing the tasks of each of its parts by a single microcontroller [7]. by systolic parallel processing technique, the execution time of the subprograms (algorithms) can be shared to be executed by several microcontrollers [7], which operate in parallel, to reduce the busy time of each microcontroller which leads to a shorter time for each function generation and higher frequency output of the system. it also becomes a powerful system of a very wide frequency range and flexibility in choosing the required mathematical functions that are widely used in communications field. thus, the future work may include the multiprocessor or multimicrocontroller implementation of the microcontroller-based function generator a step toward a microcontrotroller-based function generator of better specification. start!! registers & mode initialization frequency hexadecimal code display!! interrupt registers enabling!! do nothing loop!! exit!! figure 2: software!! input frequenc group2 ! waveform output waveforms at 89c51 microcontroller clock display keypad dac buffer stage buffer stage amplifier stage figure 1: hardware-based scheme!! group1 ! wavefor riyadh a.h. al-helali al-khwarizmi engineering journal, vol.4 , no. 1 pp 48-57 (2008) òñ !! riyadh a.h. al-helali al-khwarizmi engineering journal, vol.4 , no. 1 pp 48-57 (2008) òò !! figure 2: continued (b): interrupt service routine program (isr)!! pressing key scanning!! load timer!! new frequency!! subroutine of waveform! generation!! reset key!! exit!! input frequency !! interrupt!! yes!! pressed!! no!! riyadh a.h. al-helali al-khwarizmi engineering journal, vol.4 , no. 1 pp 48-57 (2008) òó !! square waveform, frequency =160 khz quasi-square waveform, frequency =250 khz !!!!!!! !!!!!!! !!!!!!! !!!!!!! !!!!!!! !!!!!!! !!!!!!! !!!!!!! !!!!!!! !!!!!!! !!!!!!! saw-tooth waveform, frequency =50 khz saw-tooth waveform, frequency =125 khz !! triangular waveform, frequency = 150 khz sine wave frequency = 1200 hz riyadh a.h. al-helali al-khwarizmi engineering journal, vol.4 , no. 1 pp 48-57 (2008) òô !! figure 3: the experimental results of the microcontroller waveforms references [1]!pei an!!“pc interfacing using!!!!! !!!!!!centronic rs 232 and game ports” !!!!!!newnes, 1998.!! [2] s. yeralanand and a. ahluwalia, programming and interfacing the! 8051 microcontroller, addison-!! !!!!!! wesley, 1995. !!!!!!!!! [3]! s.r. bowes, c. eng., m.i. mech. e., and m.j. mount, microprocessor control of pwm! inverters!”!iee proc. vol. 128, pp.293-304, pt.b, no.6, november 1981!! [4] s. mackenzie, the 8051 microcontroller, prentice-hall. inc.,1999! [5] m. james, microcontroller! cookbook, newnes, 1997! [6] “intelligent 4 digit dot matrix! alphanumeric led displays!”!rs data sheet, po box 99, corby,! northants, nn179rs, pp. 232-249, march 1997.!!! [7]!riyadh a.h. al-helali!!“systolic! algorithms of lms, rls adaptive!(fir) digital filters for adaptive channel equalization. “ msc. thesis, university of baghdad, baghdad, oct. 2005. sine wave, frequency = 20 khz figure 3: continued riyadh a.h. al-helali al-khwarizmi engineering journal, vol.4 , no. 1 pp 48-57 (2008) òõ !! !مایكروي(مولد ذبذبات یتحكم من متحكم متناھي الدقة إسماعیل عبد اهللا محمد عمار إسماعیل عبد اهللا . د.أ ھاللي ریاض علي عبد الحسین ال قسم شبكات الحاسبات سة الكھربائیة قسم الھند قسم الھندسة الكھربائیة االجتماعیة وزارة العمل والشؤون ة بغداد جامع ستنصریة الجامعة الم :خالصة ة اھي بالدق یطر متن ریحة مس ن ش تحكم م یطر (تتضمن المقالة وصف لمولد ذبذبات ذو مدى واسع من الترددات تم بناؤه ب مس ة , ذبذبة مربعة, بات تولید موجة جیبیھیمكن لمولد الذبذ) مایكروي بھ مربع ار , ذبذبة ش ن المنش ة س ات , ذبذب ب متطلب ة حس ة مثلثی وذبذب .مستخدم الجھاز رة ة كبی ة لدرج ان المنظوم زال كی م اخت دقیق .باالستفادة من إمكانیات المعالجة للمسیطر المایكروي ت یطر ال لة للمس ریحة المنفص أن الش .الصیانة وزیادة مرونة السیطرة الرقمیة, األشكال الموجیة منحتنا إمكانیة التحسین في موثوقیة التصنیعوالمستخدمة كأداة لتولید ة " لقد تم بناء المنظومة عملیا ة الكھربائی م الھندس ي قس االت وف وزارة االتص ة ل ث إن -وفحصھا في عدة مراكز عملی داد حی ة بغ جامع .والمھني التعلیم األكادیميام الجھاز في مختبرات الفحص كانت جیدة وأقرت بعض المراكز إمكانیة استخد تقییم نتائج group 1 waveforms group 1 waveforms s m 0 5 . 0 s m s m s m · s m · · · s m s m microcontroller-based function generator riyadh a.h. al-helali al-khwarizmi engineering journal, vol.4 , no. 1 pp 48-57 (2008) al-khwarizmi engineering journal al-khwarizmi engineering journal, vol.4 , no.1 , pp 4857 (2008 ) microcontroller-based function generator riyadh a.h. al-helali electrical engineering al-mustansiriyah university dr. ismail a. mohammed electrical engineering baghdad university ammar i. abdullah computer electrical ministry of work & social insurance (received 29 may 2007 ; accepted 5 february 2008) abstract: this paper describes a microcontroller-based function generator system. by the function generator sine wave, square wave, quasi-square wave, saw-tooth and triangular waveforms are generated over a wide frequency range according to user requirements. by utilizing processing capabilities of the microcontroller the hardware is minimized exceedingly. the output waveform shapes are digitally-controlled to achieve the required wave shape. the single chip microcomputer of waveform generation equipment offers the possibility of improvements in manufacture reliability, maintenance and servicing and increased control flexibility. the system is built and tested. the results of test were satisfactory and appreciated by test engineers at different centers of ministry of communications. keywords: microcontrollers & microcomputers, programmable controllers, waveform generation. introduction: educational institutions and colleges as well as test engineers need a function generator that generates certain shapes of waveforms at a wide range of frequency. the potential and versatility of function generation techniques have not yet been fully realized, and in the past have been limited by the conventional hardwired an analogue and digital circuits which were available [1,2]. this complicates the circuit and increases the cost of the instrument. the operational advantage of the ml2036 (micro linear) [1] is only a sine wave generator capable of producing a sine wave signal with a frequency from dc to 50 khz and it only needs a few components but has limited frequency range, while the experimental circuit of the hsp45102 (programmable generator) [1] used the centronic experimental board. the control software [1] is written in turbo pascal 6, thus, the experimental circuit operation depends on the pc, which passes through languages translators via compilation process and assembly process. the control program that is fitted into the on-chip rom of the microcontroller-based system deals with interrupts to generate the required function [2]. since the important feature of microcontrollers is the built-in interrupt system. a microcontroller-based system is numerically attractive since it offers increased flexibility, particularly in choosing the required frequency among a wide range of frequencies. these advantages inevitably result from a reduction in the complex control circuitry, which may be progressively replaced by microcontroller software. then it is possible to generate any frequency waveform is previously assigned without altering the hardware. to reduce the components and instrument cost a software-based system is to be designed and built. it is possible to proceed directly and attempt to implement, design a microprocessor, one of the previously developed hardware analogue or discrete digital-control technique [3]. however, to take a full advantage of the shift in emphasis from hardware to software design, and make effective use of the computing power of the microprocessor, a new and more fundamental approach to system design is required. by building algorithms to generate the various waveforms and control programs the required waveform can be generated with a minimum number of components. reducing the components and adopting software increase the reliability of the system and flexibility of the system operation based technique [3,4]. real-time generation of digital waves the “real-time” generation of a digital wave using an 89c51-version microcontroller utilizes an algorithm that consists of many subroutines to produce the required waveform. therefore, each wave takes subroutine execution time which is different from that of another wave generation and depending on the usage of the instruction sets to form the right creation with exact time interval. the approach to be used for generating a periodic quasi-square wave on a certain output port of the microcontroller with the required frequency is to create intervals of various lengths for setting the output port in one hand and resetting it in the other hand. it is possible to create a quasi-square wave with variable duty cycles, thus, the software running the timer is the best choice to create time delays. the creation of a square wave used the same approach of a quasi-square, with a duty cycle of 50%. another approach for creating it by using time interrupts; with time interrupts enabled [4,5], the event that generates the interrupt is the setting of the timer flag upon overflow of the timer registers. the triangular wave can be generated using a software up/down counter, the rate at which this counter is incremented (or decremented) determines the frequency and accuracy of the generation process. it also can be achieved based upon either resetting the up/down counter at the start of each cycle or deriving the interrupt signal to the cpu from the up/down timers [3]. the saw-tooth wave algorithm is achieved by using software based on up/down counter that is incremented with a suitable step value for resetting the maximum values register to produce the required frequency. the “real-time” generation of a sine wave using a microcomputer algorithm is time consuming [3,4]. for example, a zilog z80 microprocessor with a 2.5 mhz clock takes about 800 to calculate one sine value [3]. it is therefore inappropriate in high frequency applications to calculate the sine wave values, as they are required in “real-time”. an alternative approach is to store the sine values in a lookup table, which is preprogrammed into on-chip code memory (rom). alternatively, the sine values may be stored in external volatile memory (ram), the values having first been calculated by the microprocessor during the initialization period prior to generator startup. the memory requirement, efficiency of operation and accuracy of output waveform depends on the number of sample values defining a cycle of the sine wave and their resolution. if, for example, the values are taken at intervals, then a complete sine wave cycle is defined by 720 values. the sine wave could be defined at a greater number of sample points, but the memory requirement is proportionally increased. the resolution of each lookup table value must be specified on the basis of the type of generation algorithm to be performed and the required accuracy of the width output values. for most applications, an 8-bits word length is sufficient and this is particularly appropriate if an 8-bit microprocessor used. the memory requirement is reduced if only one half or even a quarter of a complete sine cycle is stored in a lookup table [2]. in either case, the bit definition is increased by one since it is no longer necessary to indicate the sine of each sample value stored. the accessing of values from the lookup table may most easily be indicated using a pointer. if a complete generated sine wave cycle is stored in memory, then the pointer cycles the lookup table. a similar procedure may be followed if only half a cycle of the sine wave is stored [3]; although, in this case, it is necessary to include a flag to indicate whether the case value obtained is of positive or negative sign. this flag is also required if only a quarter of a cycle is stored. in this case, the pointer moves up and down the lookup table instead of in one direction. hardware-based system in this system, the microcontroller is only required to generate the variable-frequency digital waveforms. a typical system arrangement is illustrated in figure 1. the system consists of the following blocks: 1. 89c51 microcontroller. 2. hexadecimal keypad. 3. intelligent dot matrix alphanumeric display [6]. 4. digital–to–analogue converter (dac) [2,3,4]. 5. buffer stages to isolate the outputs. 6. amplifier stage. there are two modes of operation, which take two stages, and generate two groups of waveforms; group 1 includes generation of triangular, saw-tooth and sine waveforms, while square and quasi-square waveforms belong to group 2. interfaces to keypads are common for microcontroller-based designs, the keypad contains 16 keys, which are connected to interrupt control pins of the microcontroller. during each interrupt, the memory is accessed and takes variable time for each generated waveform. while the 2416 [6], is a four digit, 5*7 dot matrix intelligent alphanumeric led display modules complete with built-in cmos driving circuitry and it is connected to port 0 of the 89c51. each character in any memory location can be addressed independently and will continue to display the character last written until another one replaces it. interfacing the real world often requires generating or sensing analog conditions this design used two transistors, two capacitors, a potentiometer, an lm301 op amp. [5], which represents the amplifier stage and mc1408l8 [4], is an 8-bit digital-to-analog converter (dac). the eight data inputs to the dac are driven from port 1 on the 89c51. writing different values on port 1 and adjusting the 1k potentiometer, the output should vary from 0 volts (p1 = 00h) to about 10 volts (p1 = ffh). the input command information, which relates the wave shape and its required frequency, is entered through the keypad. by pressing the appropriate key, an interrupt signal is driven that executes the interrupt service routine (isr) algorithm, then the memory is accessed and output the required waveform. each key of the keypad corresponds to a certain (isr). there are (12) isrs carrying out the following functions: (i) defining the frequency. (ii) adjusting the display digits using (4) keys. (iii) selecting the right frequency page of the program using (2) keys. (iv) choosing the wave shape using one of (5) keys. the linear-mode operation that generates waveforms of group 1 through port 1 of the microcontroller to the digital-to-analogue converter then produces the analogue signal at low power level. the levels of voltage and current can be amplified by using an amplifier stage to get the required specifications. the switching-mode generation that generates waveforms of group 2 through one pin of port 4 of the microcontroller and it is also amplified using the same amplifier stage. an optocoupler is used as a buffer stage between the microcontroller and the power circuit [2]. software system it is important first to consider the time constraints imposed when “real-time” generation of the digital waveforms is attempted in the microcontroller software. the software generation of the waveforms has already been described the maximum frequency of the function generator. in order to assess the time constraints, on square and quasi-square wave, have one cycle taking minimum time typically is 4 and maximum value, which is loaded in the timer registers. but for saw-tooth and triangular waveforms, assume that one cycle involves 256 (maximum) increments, 256 (maximum) decrements and 512 comparisons, each update taking typically 3 . the sine wave is defined by 1024 (maximum) sample per cycle, each taking typically 15 to be accessed from memory and loaded it to the microprocessor, for a z80 with a 2.5 mhz clock, the maximum frequency from the microprocessor is limited to approximately 12 hz [3]. to generate the time period in real time it is required that the time counter to be loaded with a value from the cpu corresponding to the required period for square and quasi-square. the rate of decrement of the counter for saw-tooth and triangular waveforms is determined by its clock. when a zero value is reached, the counter output changes and generates an interrupt signal to inform the cpu that the time period has been completed. the cpu responds by loading the next period into the counter and changes the signal from the output port, hence the required waveform is generated. the software-based system consists of two algorithms, the main program and the interrupt service routine program. the main program initializes mode timers, interrupt registers and other general purpose registers while the interrupt service routine portioned into five subroutines, each one consists of a number of pages, which operates at a certain frequency band generation, that generate its waveform. the software algorithm has the following tasks: 1. main program, which executes the following, tasks: selecting the timer mode of operation. · enabling the external interrupt registers. · assigning the external interrupt according to the connection of the keypad. · performing the do nothing loop statement waiting for pressing any key of the keypad. 2. interrupt service routine program (isr) which executes the following tasks:  scanning the row and column lines of the keypad to determine if a key is pressed.  calling a delay function subroutine to allow for a delay time between increment and decrement steps of the keys.  selecting the frequency band of generation.  displaying the frequency hexadecimal code on the display.  running the subroutine of waveform generation. the software interrupt routine is used for servicing the external interrupt shown in the flow diagram in figure 2, together with the main program function used to generate the waveforms. experimental results the experimental results presented in this section were obtained using an experimental microcontroller function generator system. an at 89c51-version microcontroller was used to provide the waveforms. the function generator implementation used is based on the microcontroller hardware configuration, which used a crystal oscillator of 12 mhz clock. all the experimental results are delivered from the analogue circuit using the software algorithm described in section 4. the experimental results have been chosen to illustrate some of the main features of microcontroller which have been discussed previously are shown in figure 3. the experimental study of these results, which is taken at a wide frequency band, shows the following specifications: quasi-square wave includes:  rise time = 25 nsec.  fall time = 0.1 .  overshooting invisible as a single pipe.  ringing invisible.  no sag.  different duty cycles.  10 volt peak-to-peak, 0.3 ma output current.  frequency range from less than 1 micro hz to 250 khz. square wave includes:  rise time = 10 nsec.  fall time = 5 nsec.  neither overshooting nor ringing or sag.  10 volt peak-to-peak, 0.3 ma output current.  frequency range from less than 0.006 hz to 166.666 khz, larger that limits can be obtained by using the quasi-square wave with duty cycle of 0.5. saw-tooth wave includes:  frequency range from (1 micro hz to 150 khz).  10 & 5 volt peak-to-peak, 0.3 ma output current. triangular wave includes:  frequency range from (1 micro hz to 166 khz).  10 & 5 volt peak-to-peak, 0.3 ma output current. · it can be generated from the saw-tooth algorithm with certain step such as 128. ( sine wave includes:  frequency range from (1 micro hz to 100 khz).  10 volt peak-to-peak, 0.3 ma output current. from the experimental waveforms shown in figure 3, a quasi-square wave generated at 250 khz, square wave at 160 khz, saw-tooth at two frequencies; upper frequency at 125 khz and lower frequency at 50 khz, triangular wave at 150 khz and sine wave of upper frequency at 20 khz and lower frequency at 1200 hz with 512 lookup table samples. therefore, the flexibility of the microcontroller software enables as for generation waveforms continuously at wide frequency band. the correct generation of the frequency wave that corresponds the required signal specifications depends upon the approximate conversion of the decimal time interval to a negative hexadecimal code numbers and the flexibility of choosing the parameters of delay relations when using theoretical calculations. the frequency fluctuation can be minimized to a very small value by actuate theoretical calculations of the entered hexadecimal code frequency numbers through the keypad. the linear-mode waveforms suffer from amplitudes decreasing and small distortion when generated above the upper frequency. this is due to least number of steps used. the main limitation of the system is the upper frequency, which is limited by the chip version, the clock frequency of the crystal oscillator, the conversion time of the digital to analogue converter to produce the output signal. the upper frequency can be increased up to 1.25 mhz for switching-mode waveforms, and up to the range of (250 khz – 750 khz) for the linear-mode waveforms, by decreasing the machine cycle time of the 89c51 cpu to less than 1 , which is used. by using a crystal oscillator of 40 mhz and fastest conversion time of the dac this value can be achieved. conclusion a microcontroller-based function generator is designed and built. the experimental results show that a waveform of acceptable accuracy could be obtained with a high degree of flexibility reduced generator size and a small number of components. the upper frequency range is limited by the switching frequency of the microcontroller. the fetch and execution time taken by the instruction pointer of the cpu are (1 ) for each machine cycle, to execute the subprograms. it can be shared by dividing the program into equal fixed-size parts (i.e., each part has the same machine cycle), and to carry out the whole work by performing the tasks of each of its parts by a single microcontroller [7]. by systolic parallel processing technique, the execution time of the subprograms (algorithms) can be shared to be executed by several microcontrollers [7], which operate in parallel, to reduce the busy time of each microcontroller which leads to a shorter time for each function generation and higher frequency output of the system. it also becomes a powerful system of a very wide frequency range and flexibility in choosing the required mathematical functions that are widely used in communications field. thus, the future work may include the multiprocessor or multimicrocontroller implementation of the microcontroller-based function generator a step toward a microcontrotroller-based function generator of better specification. figure 2: continued square waveform, frequency =160 khz quasi-square waveform, frequency =250 khz saw-tooth waveform, frequency =50 khz saw-tooth waveform, frequency =125 khz figure 3: the experimental results of the microcontroller waveforms references [1] pei an, “pc interfacing using centronic rs 232 and game ports” newnes, 1998. [2] s. yeralanand and a. ahluwalia, programming and interfacing the 8051 microcontroller, addison wesley, 1995. [3] s.r. bowes, c. eng., m.i. mech. e., and m.j. mount, microprocessor control of pwm inverters.” iee proc. vol. 128, pp.293-304, pt.b, no.6, november 1981. [4] s. mackenzie, the 8051 microcontroller, prentice-hall. inc.,1999. [5] m. james, microcontroller cookbook, newnes, 1997. [6] “intelligent 4 digit dot matrix alphanumeric led displays.” rs data sheet, po box 99, corby, northants, nn179rs, pp. 232-249, march 1997. [7] riyadh a.h. al-helali, “systolic algorithms of lms, rls adaptive (fir) digital filters for adaptive channel equalization. “ msc. thesis, university of baghdad, baghdad, oct. 2005. مولد ذبذبات يتحكم من متحكم متناهي الدقة (مايكروي) رياض علي عبد الحسين الهلالي أ.د. إسماعيل عبد الله محمد عمار إسماعيل عبد الله قسم الهندسة الكهربائية قسم الهندسة الكهربائية قسم شبكات الحاسبات الجامعة المستنصرية جامعة بغداد وزارة العمل والشؤون الاجتماعية خلاصة: تتضمن المقالة وصف لمولد ذبذبات ذو مدى واسع من الترددات تم بناؤه بتحكم من شريحة مسيطر متناهي بالدقة (مسيطر مايكروي) يمكن لمولد الذبذبات توليد موجة جيبيه, ذبذبة مربعة, ذبذبة شبه مربعة, ذبذبة سن المنشار, وذبذبة مثلثية حسب متطلبات مستخدم الجهاز. بالاستفادة من إمكانيات المعالجة للمسيطر المايكروي تم اختزال كيان المنظومة لدرجة كبيرة.أن الشريحة المنفصلة للمسيطر الدقيق والمستخدمة كأداة لتوليد الأشكال الموجية منحتنا إمكانية التحسين في موثوقية التصنيع, الصيانة وزيادة مرونة السيطرة الرقمية. لقد تم بناء المنظومة عمليا" وفحصها في عدة مراكز عملية لوزارة الاتصالات وفي قسم الهندسة الكهربائية جامعة بغداد حيث إن تقييم نتائج الفحص كانت جيدة وأقرت بعض المراكز إمكانية استخدام الجهاز في مختبرات التعليم الأكاديمي والمهني. load timer input frequency new frequency subroutine of waveform generation reset key exit yes no pressed interrupt pressing key scanning (b): interrupt service routine program (isr) not pressed yes no pressed (a): main program figure 2: software-based scheme flow diagram start registers & timer mode initialization frequency hexadecimal code display interrupt registers enabling do nothing loop exit reset key figure 1: hardware-based scheme amplifier stage buffer stage buffer stage dac keypad display clock at 89c51 microcontroller output waveforms group2 waveforms � input frequency group1 waveforms � � � sine wave frequency = 1200 hz triangular waveform, frequency = 150 khz sine wave, frequency = 20 khz figure 3: continued � embed pbrush ��� page page _1168956564.unknown _1169396737.unknown _1169458646.unknown _1173207870 _1169156688.unknown _1168954742.unknown 32 al-khwarizmi engineering journal al-khwarizmi engineering journal, vol.3, no2,pp32 -48 (2007) effect of the mechanical and thermal stresses of rotating blades assist. prof. dr. nabeel k. al-sahib malik m. ali baghdad university / al-khwarizmi college of engineering (((rrreeeccceeeiiivvveeeddd111111dddeeeccceeemmmbbbeeerrr 222000000666 ;;; aaacccccceeepppttteeeddd 222555 aaappprrriiilll 222000000777))) abstract: rotating blades are the important parts in gas turbines. hence, an accurate mathematical estimation (f.e.m) of the stresses and deformations characteristics was required in the design applications to avoid failure. in recent year’s there are researchers interest in the effect of temperature on solid bodies has greatly increased, the main of this study investigated the thermal and rotational effects. so, the thermal stresses due to high pressure and temperature are studies, also determine the steady state stresses and deformations of rotating blades due to mechanical effect. many parameters such as thickness and centre of rotating are investigated in this paper. the study results can ensure good recommendation for the effect of the mechanical and thermal stresses of rotary blades. keywords: thermal stresses, finite element method, mechanical stresses , blade material , design . introduction rotating blades was one of the common structural elements used in several practical machines such as turbomachinery system, turbojet engines, turbofan, and helicopter rotors. because turbomachinary blades are assumed as a shell, the numerical technique should be capable of representing this complicated structure based upon the shell theory. in this paper the type of rotating blades were used is rectangular blade, the geometry for this type was show in figure (1). ramamurti and sreenivasamurthy [1] studied the dynamic stress analysis of rotating twisted and tapered blades. the finite element method was used to determine the stresses and deformations. three-dimensional, twenty-node isoparametric elements have been used for the analysis. extensive analysis has been done for various pre-twist angles, skew angles, breadth to length ratios, and breadth to thickness ratios of the blades. experiments were carried out to determine the stresses for the verification of the numerical results. lee [2] determined the frequencies and mode shapes of turbomachinery blade having both camber and twist. the body forces were considered to be centrifugal forces generated within the shell due to rotation of the blade. omprakash and ramamurti this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. nabeel k. al-sahib /al-khwarizmi engineering journal ,vol.3, no2 . pp32-48 (2007)33 33 metal. but for high temperature gas turbines, “nimonic” alloy series are recommended. they are basically nickel-chromium alloys, which withstand oxidation, mechanical stresses, and creep at working temperatures in excess of 1000o c. in the middle part of the turbine, the temperature and stress conditions are moderate, but corrosion is likely. brass is probably the most suitable material. in the final stages, and especially in large machines, the blades are long and heavily stressed. fatigue action due to vibration may exist. further than this, anti corrosion properties are also desirable. brass is a suitable material where the stress conditions allow of its use, but when the stresses are high, 5% nickel steel, stainless steel, monel metal or phosphor bronze may be used. turbine blade design turbine blades operate at 1400 0c and are required to have a service life of 1000020000 hours. the techniques used to meet these requirements are: 1) the use of nickel based superalloys (containing many precipitates, solid solution atoms and having high oxidation resistance) 2) the blades are cast a single crystal. this means that there are no grain boundaries within the structure and thus minimizes creep see fig. (2) 3) the blades are internally cooled to allow increased operating temperatures. typical cooling design features are shown in fig. (3) 4) the blades are coated to increase the oxidation resistance as shown in fig. (4). a timeline of techniques to raise engineoperating temperatures is shown in fig. (5 &6) [3] carried out the steady state, dynamic stress and deformation analysis of high pressure stage turbomachinery bladed discs taking into account all the geometric complexities involved and included the contributions due to initial stress and membrane behavior, which used a triangular shell element with six degrees of freedom per node. yoo [4] studied the vibration analysis of rotating pre-twisted blade with a concentrated mass. the blade has an arbitrary orientation with respect to the rigid hub to which it is fixed. the equations of motion are derived based on a modeling method that employs hybrid deformation variables. the resulting equation for the vibration analysis was transformed in the dimensionless parameters on the model characteristics of the rotating blades were investigated through numerical analysis blade materials the elimination of blade corrosion and designing against creep and fatigue, to a large extent, is a problem of finding suitable materials. another factor, especially in high-pressure work, is the working temperature of the blades. under high temperatures, some materials tend to disintegrate, and certain mechanical properties, e.g. hardness (in the sense of resistance to abrasion), are affected adversely. the properties, which are desirable for example in turbine blading, vary according to the conditions of operation and according to the location of the blading in the turbine [5]. at highpressure end, the temperature is high, and the blades are sometimes subjected to erosive action. great strength is not required as the blades are usually short. the material should be hard at high temperatures. suitable materials are 5% nickel steel, stainless steel, and monel this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. nabeel k. al-sahib /al-khwarizmi engineering journal ,vol.3, no2 . pp32-48 (2007)34 34 finite element technique the difficulties in evaluating the stress and deformations of rotating blades comes from the complex geometry of blades due to asymmetry of cross-section, pre-twist, and mounting the blades at a skew angle to the rotating disk. the pre-twist and skew of the blade cause coupling in both bending directions, and the asymmetry of the crosssection causes coupling with the tensional motion of the blade. for the above complexities, all previous investigations in this field had declared that plate or shell analysis for blades is suitable and reliable. therefore, the shell theories with finite element provide a useful tool to analyze such structures. a superparametric shell element will be used to investigate the thermal and mechanical stresses of rotating blades. this element consists of four corner and four midside nodes as shown in fig. (7). the degrees of freedom considered at the s are the three translations u, v, w of the midsurface and two rotations α and β of the normal to the midsurface. the cartesian coordinates of any point of the shell and the curvilinear coordinates can be written in the form:                                   h n m l f z y x f z y x i i i i i i i i 3 3 3 2  ……(1) where l3i, m3i and n3i are the direction cosines of the normal to the middle surface. here fi is a function taking a value of unity at the node i and zero at all other nodes, it is called as “shape function “(4).as shown in table.(1). in the kinematics formulation two assumptions are imposed: 1nodal fiber is inextensible. 2only small rotations are considered. the displacements at any point (ξ, η, ζ) can be expressed in terms of the nodal displacements as                               i i i i i i i i i i i f h n w v u f w v u    2 8 1 8 1 ... …. (2) in this formula the symbol i denote the following matrix:               ii ii ii i nn mm ll 12 12 12  column 1 in this array contains negative values of the direction cosines of the second tangential vector v2i , and column 2 has the direction cosines for the first tangential vector v1i. these vector are orthogonal to the vector v3i and to each other. the strain in the direction the normal to the mid-surface is assumed to be negligible ( z  ) the normal to the mid-surface of the shell element will remain normal to the midsurface after deformation. the displacement shape functions may be cast into the matrix form: [fi]=[fai]+ζ [fbi] (i=1,2…8) ………(3) where [fai]=           00100 00010 00001 , fi & [fbi]=              ii ii ii nn mm ll 12 12 12 000 000 000 2 ih fi …..… (4) the 3 x 3 jacobian matrix required in this formulation is: this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. nabeel k. al-sahib /al-khwarizmi engineering journal ,vol.3, no2 . pp32-48 (2007) 35 35 [j]=              ,,, ,,, ,,, zyx zyx zyx ……………………(5) where “,” indicate differentiation with respected to the symbol following the coma. the derivatives in matrix [j] can be found from equation (1) i h i i i h i ii i i i h i ii i i lfx lfxfx lfxfx i i i 32 8 1 , 32 8 1 , 8 1 ,, 32 8 1 , 8 1 ,,               and so on for this element, six types of non-zero strains exit, as follows:                                              zx yz xy z y x zx yz xy z y x uw wv vu w v u ,, ,, ,, , , ,        …….…. (6) the stress-resultant vector in the local coordinate system is, {f′}={f x′f y′f x′y′ q y′ q x′ m x′ m y′ m x′y′ } t………..(7) where q x′ was the shear stress per unit length in the x and y direction. the relationship between the stress resultants and the generalized strains can be stated as follows, {f′}=[d′]{ε′} ………………………(8) where [d′] is the rigidity matrix. a typical rigidity matrix for flat plate shell is given                                   24 )1( 1212 1212 2 1 2 1 2 1 2 2 22 22 0000000 000000 000000 0000000 0000000 0000000 0000001 0000001 1          h hh hh k keh d ..(9) k =shear shape factor (assumed k=1.2) (5). numerical solution two cases were studied, steady state and thermal stresses as follows: steady -state analysis in this section the steady state stresses and deformations were calculated, the blades considered were made of steel; and the material properties are: modules of elasticity = 207 * 103 mpa, poisson’s ratio = 0.3, density = 7850 kg/m3. other information are: speed of rotation = 5000 r.p.m, disk radius/width = 4, width = 0.05m. in this respect, a numerical study for a rectangular cross-section blade is given in details because it is a common model. comparison of the results a comparison with experimental published results is achieved between the present work and the experimental work [1]. in this comparison, a rectangular steel blade is considered, having the following dimensions and material properties: length = 100 mm, width = 25mm, thickness =3mm, skew angle = 90o , radius to root = 125mm, and maximum speed of rotation = 2500 r.p.m, modulus of elasticity = 207 * 103 mpa, poisson’s ratio =0.3, density = 7850 kg/m3 . strain gauges were used as transducers and the results are shown in table 2 effect of rotational speed the variation of stresses and deformations with eight speeds of rotation (250, 500, 750, 1000, 1250, 1750, and 2000 r.p.m) for three aspect this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. nabeel k. al-sahib /al-khwarizmi engineering journal ,vol.3, no2 . pp32-48 (2007)36 36 ratios (3, 4, and 5) are investigated and shown in fig. (9,10, and 11) show the variations of v-deflection, xxstresses, yystresses respectively with speed of rotation. it was observed that stresses and deformations increase that when the speed of rotation increased too. effect of thickness in order to investigate the thickness of blade, eight thickness (1.5, 2, 2.5, 3, 3.5, 4, 4.5 and 5 mm) and three aspect ratios (3, 4 and 5) were selected for this investigated. figs (12, 13, and 14) show the variations of vdeflection, xx-stresses, yy-stresses respectively with thickness. it can be noted that increases of the blade thickness leads to decreases in the stresses and deformations (i.e. thin blades give greater stresses and deformations than the thick blades) and that due the higher reduction in the structural stiffness. also, it can be seen that when the aspect ratio increases the reduction in stresses and deformations increases. blade deflection due to thermal stresses the blade is relatively thin, and thus the thermal gradient through the thickness of the blade is assumed negligible. therefore, the blade is assumed to have a uniform temperature equal to the surface temperature. this simplifies the thermal stress analysis and results in a simple linear relation:[12] u=αtl ………………………….…(10) where l= blade length (m), α= thermal expansion coefficient (1/co) and t=temperature (co). figs (15, 16, 17, and 18) show the variations of temperature udeflection, xx-stresses, yy-stresses respectively with x-axis and figs (19, 20, 21, and 22) show the contour of temperature, udeflection, xx-stresses, yy-stresses respectively. it can be noted that increases of the blade temperature leads to increase in the stresses and deformations conclusions: the conclusions obtain from the present work can be summarized as when the increases of the blade thickness leads to decrease in the stresses and deformation, (i.e. thin blades give greater stresses and deformations than the thick blades) and that is duo to the higher reduction in structural stiffness, the generated stresses will be increases for the blades having large aspect ratios, as well as the deformations become large, since the total mass of the structure is proportional to the aspect ratio. the increases of the blade temperature leads to increase in the stresses and deformations so, shaped film-cooling and full coverage film cooling are the most useful cooling schemes for reducing the amount of cooling air and decreasing thermal stresses. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. nabeel k. al-sahib /al-khwarizmi engineering journal ,vol.3, no2 . pp32-48 (2007)37 37 this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. nabeel k. al-sahib /al-khwarizmi engineering journal ,vol.3, no2 . pp32-48 (2007)38 38 fig. (2) turbine blades cast to promote different grain structures [9] fig. (3) blade cooling techniques [10] fig. (4) history of turbine blade coating systems [11] this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. nabeel k. al-sahib /al-khwarizmi engineering journal ,vol.3, no2 . pp32-48 (2007)39 39 fig. (5) developments to increase engine-operating temperatures [10] fig. (6) developments to increase turbine metal capability [8] ξ ηζ ζ=1 ζ=-1 η=-1 η=1 ξ=1 ξ=-1 fig. (7) eight noded shell element this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. nabeel k. al-sahib /al-khwarizmi engineering journal ,vol.3, no2 . pp32-48 (2007)40 40 serendipity 8-node element: corner nodes: )1)(1)(1( 4 1  iiiiif  midside nodes: )1)(1( 2 1 )1)(1( 2 1 2222   iiiiif table (1) shape function for midsurface interpolation of shell elements table 2 comparison with experimental results. (radial stress) αo distance exp. (mpa) present work (mpa) ω (r.p.m) 0 0.1 l 9.1154 9.0086 2500 15 0.25 l 5.7115 5.5613 2000 z, w βi y, v fig. (8) degrees of freedom at a node i this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. nabeel k. al-sahib /al-khwarizmi engineering journal ,vol.3, no2 . pp32-48 (2007)41 41 0 1 2 3 4 5 6 0 250 500 750 1000 1250 1500 1750 2000 2250 speed of rotation (r.p.m) v_ de fle ct io n {m m }x 10 ^ 2 l/b=3 l/b=4 l/b=5 0 1 2 3 4 5 6 7 8 9 0 250 500 750 1000 1250 1500 1750 2000 2250 speed of rotation (r.p.m) xx _s tr es se s{ m pa } l/b=3 l/b=4 l/b=5 fig. (9) variation of v-deflection with speed of rotation fig. (10) variation of xx-stresses with speed of rotation fig. (11) variation of yy-stresses with speed of rotation 0 3 6 9 12 15 18 21 24 27 30 33 0 250 500 750 1000 1250 1500 1750 2000 2250 speed of rotation (r.p.m) yy _ st re ss es {m pa } l/b=3 l/b=4 l/b=5 r=0.225 m, h=0.0018 m skew angle =20o pre-twist angle = 12o al-alloy (5052) this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. nabeel k. al-sahib /al-khwarizmi engineering journal ,vol.3, no2 . pp32-48 (2007)42 42 0 1 2 3 4 5 6 7 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 thickness (mm) v_ de fle ct io n {m m }1 0^ _2 l/b=3 l/b=4 l/b=5 0 1 2 3 4 5 6 7 8 9 10 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 thickness (mm) xx _ st re ss es {m pa } l/b=3 l/b=4 l/b=5 0 5 10 15 20 25 30 35 40 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 thickness (mm) yy _ st re ss es {m pa } l/b=3 l/b=4 l/b=5 fig. (12) variation of v-deflection with thickness fig. (13) variation of xx-stresses with thickness fig. (14) variation of yy-stresses with thickness r=0.225 m, ω=2000 r.p.m skew angle =20o pre-twist angle = 12o al-alloy (5052) this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. nabeel k. al-sahib /al-khwarizmi engineering journal ,vol.3, no2 . pp32-48 (2007)43 43 0 1 0 0 2 0 0 3 0 0 4 0 0 5 0 0 6 0 0 7 0 0 0 0 . 0 0 5 0 . 0 1 0 . 0 1 5 0 . 0 2 0 . 0 2 5 0 . 0 3 x a x is { c m } t em pe ra tu re {c } 0 . 0 0 e + 0 0 2 . 0 0 e + 0 2 4 . 0 0 e + 0 2 6 . 0 0 e + 0 2 8 . 0 0 e + 0 2 1 . 0 0 e + 0 3 1 . 2 0 e + 0 3 1 . 4 0 e + 0 3 1 . 6 0 e + 0 3 0 0 . 0 1 0 . 0 2 0 . 0 3 x a x is { c m } xx _ st re s se s {m p a} fig. (15 variation of temperature with x-axis fig. (18) variation of yy-stresses with x-axis 0 . 0 0 e + 0 0 1 . 0 0 e + 0 2 2 . 0 0 e + 0 2 3 . 0 0 e + 0 2 4 . 0 0 e + 0 2 5 . 0 0 e + 0 2 6 . 0 0 e + 0 2 7 . 0 0 e + 0 2 8 . 0 0 e + 0 2 9 . 0 0 e + 0 2 1 . 0 0 e + 0 3 0 0 . 0 0 5 0 . 0 1 0 . 0 1 5 0 . 0 2 0 . 0 2 5 0 . 0 3 x a x is { c m } yy _s tr es se s {m p a} 0 . 3 5 0 . 3 9 0 . 4 3 0 . 4 7 0 . 5 1 0 . 5 5 0 0 . 0 0 5 0 . 0 1 0 . 0 1 5 0 . 0 2 0 . 0 2 5 0 . 0 3 x a x is { c m } u _d ef le c tio n {m m } fig. (17) variation of xx-stresses with x-axis fig. (16) variation of u-deflection with x-axis this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. nabeel k. al-sahib /al-khwarizmi engineering journal ,vol.3, no2 . pp32-48 (2007)44 44 fig. (19) contour of temperature fig. (20) contour of u-deflection this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. nabeel k. al-sahib /al-khwarizmi engineering journal ,vol.3, no2 . pp32-48 (2007)45 45 fig. (21) contour of xx-stresses fig. (22) contour of yy-stresses this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. nabeel k. al-sahib /al-khwarizmi engineering journal ,vol.3, no2 . pp32-48 (2007)46 46 reference: 1ramamurti, and sreenivasamurthy; “dynamic stress analysis of rotating twisted and tapered blades”, j. strain analysis, vol. 15, no. 3, 1980 2 j. k. lee, a. w. leissa and a. j. wang, “vibration of blades with variable thickness and curvature by shell theory”, j. of eng. for gas turbine and power, vol. 106, pp. 1116, 1984. 3v. omprakash and v. ramamurti, “dynamic stress analysis of rotating turbomachinery blade-disc systems”, j. of computers and structures, vol. 32, no. 2, pp. 477-488, 1989. 4h. h. yoo, j. ykwak and j. ghung, “vibration analysis of rotating pretwist blades with a concentrated mass”, j. of sound and vibration, vol. 240, no. 5, pp. 891-908, 2001 5kearton, w. j. ,”steam turbine operation”, sir petman & sons, ltd., 4th ed. 1945 6. flower, h.m. ed., high performance materials in aerospace, chapman & hall, london, 7. sims, c.t., stoloff, n.s. & hagel, w.c. eds., superalloys ii, john wiley & sons, new york, 1987 8. askeland, d.r., the science and engineering of materials: third si edition, chapman and hall, london, 1996 9. callister, w.d., jr, materials science and engineering an introduction: 5th edition, john wiley and sons inc, new york, 2000 10. ashby, m.f. & jones, d.r.h., engineering materials 1: an introduction to their properties and applications, 2nd edition, butterworth heinemann, oxford, 1997 11. sims, c.t., stoloff, n.s. & hagel, w.c. eds., superalloys ii, john wiley & sons, new york, 1987 12aeronautical materials – teacher reference, school of material science and engineering, university of new south wales 2001 this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. nabeel k. al-sahib /al-khwarizmi engineering journal ,vol.3, no2 . pp32-48 (2007)48 48 internet links general aerospace http://www.howstuffworks.com/sc-aviation-transportation.htm http://www.matweb.com/ http://www.howstuffworks.com/airplane.htm http://www.howstuffworks.com/search/index.htm?words=materials+engineering http://smc.larc.nasa.gov/coe/ http://as.wm.edu/nondestructive.html ex.html http://www.grc.nasa.gov/www/hsr/epmairf.html http://www.grc.nasa.gov/www/hsr/ind http://www.boeing.com/commercial/aeromagazine/aero_07/corrosn.html http://www.boeing.com/commercial/747family/background.html http://www.boeing.com/commercial/747family/index.html http://www.boeing.com/news/feature/new747/passenger.html turbines and materials http://www.gas-turbines.com/begin/index.htm#history http://www.howstuffworks.com/turbine.htm http://www.sti-tech.com/ this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. nabeel k. al-sahib /al-khwarizmi engineering journal ,vol.3, no2 . pp32-48 (2007)49 49 تأثیرات االجھادات المیكانیكیة والحراریة للمراوح الدوارة مالك محمد علي عبد الصاحب نبیل كاظم. د.م.أ جامعة بغداد -كلیة ھندسة الخوارزمي :الخالصة أن التمثیل ھي من األجزاء المھمة في التوربینان الغازیة، لذلك لدوارةألمراوح أ لألجھادات والتشوھات ضروري من اجل التطبیقات ) طریقة العناصر المحدودة (الریاضي بتأثیر درجات الحرارة على الباحثین في السنوات األخیرة زاد أھتمام. التصمیمیة لتجنب الفشل جھادات الحراریة الناتجة من ، دراسة األ من ھذه الدراسة الھدف الرئیسي. األجسام الصلبة جھادات المستقرة والتشوھات للمراوح وكذلك تم أحتساب األ. الضغط ودرجة الحرارة العالیین مثل عنھا في ھذا البحث تقصيتم ال العدید من العوامل. ثیرات المیكانیكیةالدوارة الناتجة من التأ ألخ.... السمك ومركز الدوران . جھادات المیكانیكیة والحراریة للمراوح الدوارة ات جیدة لتأثیرات األصینتائج الدراسة تؤمن تو this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ (microsoft word \344\346\321 \344\310\355\34180-88) al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 15, no.2, june , (2019) p.p. 8088 design and implementation of scada system for sugar production line noor n. abdulsattar* faiz f. mustafa** suha m. hadi*** *,**department of automated manufacturing engineering/ al-khwarizmi engineering college/ university of baghdad ***department of information technology/ al-khwarizmi engineering college/university of baghdad /iraq *email:nooranabil94@gmail.com ** email:dr.faiz@kecbu.uobaghdad.edu.iq *** email:dr.suhahadi@gmail.com (received 4 november 2018; accepted 9 january 2019) https://doi.org/10.22153/kej.2019.01.002 abstract scada is the technology that allows the operator to gather data from one or more various facilities and to send control instructions to those facilities. this paper represents an adaptable and low cost scada system for a particular sugar manufacturing process, by using programmable logic controls (siemens s7-1200, 1214dc/ dc/ rly). the system will control and monitor the laboratory production line chose from sugar industry. the project comprises of two sections the first one is the hardware section that has been designed, and built using components suitable for making it for laboratory purposes, and the second section was the software as the plc programming, designing the hmi, creating alarms and trending system. the system will have two hmi screens according to the two operating states of system (automatic and manual), the operator can choose between them by a selector switch, this method helps the operators when fixing a failure and wanting to check it without operating all the process. the result has accomplished the goals of controlling, the parameters (temperature, flow, humidity) were monitored, failure was detected by an alarm. keywords: scada, programmable logic controls, integrated automation, sugar industry. 1. introduction scada systems became popular to arise the efficient monitoring and control of distributed remote equipment. today scada systems include operator-level software applications for viewing, supervising and troubleshooting local machines and process activities. powerful software technologies are used for controlling and monitoring equipment in easy-to-use web-based applications, e.g., platforms: pcs7 – siemens, cx-supervisor – omron, genesis 32 – iconix [1]. the term supervisory control is associated with (i) the process industries, where it manages the activities of a number of integrated operation units to achieve certain economic objectives for process; and with (ii) the discrete manufacturing automation, where it coordinates the activities of several interacting pieces of equipment in manufacturing cells or systems, such as a machines interconnected group by a material handling system [2]. scada involves the collecting of information, transferring to the central site, carrying out any necessary analysis and control, and then displaying that information on a number of operator screens or displays. the required control actions are then conveyed back to the process [3]. control and supervision tasks of industrial plants are distributed over wide areas, and are characterized by many sensing and actuation points (in order of hundreds or even thousands of units) as in petrol chemical plants, paper factories, newspaper rotary printing presses, plants for extraction, bottling of alimentary juices, noor n. abdulsattar al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 8088 (2019) 81 energy monitoring, etc. they require the use of sophisticated automation schemes that must be able to grant access to production data and field distributed variables at large distances, and from various levels of factory automation (field, control, supervision, etc.) [4]. programmable logic controls (plcs) are used for system control. as the need to monitor and control more devices in the plant grew, the plcs are distributed and the systems became more intelligent and smaller in size. scada and plc are types of control systems. nowadays, there are systems that incorporate all these concepts in one integrated automation system. totally integrated automation (tia) is the foundation to implement industry specific automation solutions that are coordinated with individual requirements, combining increased productivity with a high level of investment security. tia offers uniform automation technology on one single platform for all applications of process automation, starting with input logistics, covering production or primary processes as well as secondary processes, up to output logistics. many researches have been discussed this subject like: r. kumar et al. [5] designed a scada system for industrial purpose to control and monitor the process plant that consists of three units, where the temperature of these units are variable, so the developed automated system collects the temperature data of different cities and maintains the production according to the consumers demands. where the consumer demand is varying according to the temperature. n. burali[6] used delta plc to control the crane movement’s. with the use of wpl software. scada used were, current and temperature of the drives have been observed by scada system in current instant. to achieve the point of automating and controlling. k. p. bindu et al. [7]managed an intelligent monitoring system of hardboard industry with the help of plc. allen bradley plc and the entire logic were created in micrologix programming software to control the parameters of required pressure and time duration of each period. the system created a fast, real-time decision making environment. the process is adaptable to any changes in production capacity or safety requirements. das.[8]provided an analysis of the simulation and components required for the implementation of an automated level control system by the help of plc(simatic s7-300). ahmed kh. et al.[9] gave a solution to plan application process by using the scada system and deal with another system (erp v7.0 simulator). to record and make supply chain report, and expecting of accomplishment or failure of the system. the manufacturing process is designed by using scada simulator which is wincc v6.0, the integration between the two systems was accomplished by opc server. r. sharma et al.[10]presented the design of a prototype of automated storage and retrieval system for small loads and to reduce the human effort and manpower. this paper includes design and structure analysis of material storage and retrieval system with the help of plc and scada. plc used (dvp dvp-64eh), wplsoft 2.30 is the software dedicated to the plc for programming purpose, rs-232 is used for serial communication. the prototype model of automated storage and retrieval system developed consists of the control hardware and software scada. in this work, a new method is added to control the process and promote the work which is creating two states for the system and chose any one of them by selective switch to help the operator through checking failed parts. plc (s71200) is used to control the implemented mechanical part and the scada system is created by tia v13 software, hmi is accomplished through wincc v13. 2. mechanicaland electronic parts the system consists of three main mechanical parts, the first one is the heating unit that combines normal water electrical heater [11] plated inside by stainless steel to suit food industry and water proof, anti-resistant temperature sensor (ds18b20), placed inside the tank to measure the syrup temperature. the second part is consisted of solenoid valve joined by typical water pipes, which served as a gate for passing the syrup after the evaporation step. then a water flow sensor is placed under the solenoid valve to determine and allow a specific amount of syrup to pass to the third part, which consists of a centrifugal container that has concaved design to allow both of mixing and centrifuging processes. the outside of the centrifugal container is covered by a layer of heavy cloth to prevent the escape of sugar crystals during the rotation. ac motor of 1600 rpm was used to rotate the centrifugal container, in addition to measure the humidity inside the crystallization unit the humiditytemperature sensor (dht11), were used. on the other hand the system also includes electronic parts: three uno-arduinos[12], each of them is responsible for one of the sensors and to convert noor n. abdulsattar al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 8088 (2019) 82 analog-to-digital signal (adc). six relays as a latching relays, that were used to convert the dc arduinos output signals into appropriate signals to enter the plc as an input. siemens s7-1200 plcserves as the major controlling unit of the system. based on the ladder logic program the plc achieves its decisions, and communicated to the computer by using pn/ie. finally the last part is the hmi siemens wincc v13 (tia) that presents the status of the system. tags were used to empower connection between the plc and hmi. 3. design and implementation this section can be divided into: 3.1 mechanical design laboratory production line as hardware system has been designed, this system consists of three units: heating unit as a tank with capacity of 20l, transferring elements (valve, flow sensor) and centrifugal unit, with dimensions of (60, 60,190) cm for the iron frame, (d= 28cm) for the tank and (30, 60) cm for the board of electronics. the system was designed to be used for laboratory purposes only. figure 1. presents the design of the system. fig. 1. the design of laboratory production line. 3.2 circuit design the main part of the automated production line machine is the siemens s7-1200 plc as shown in figure2. where the input signals of temperature, flow and humidity are given to the plc as analogue and digital outputs from uno-arduino, from the computer by the arduino software integrated development environment (ide). the output signals of the plc are given to the components that connected to the plc as actuators, like heater, valve and motor, for controlling them specifically. fig. 2. (the designed circuit of the project). 3.3 production line implementation the implementation is divided into four steps: a. building the system: the production line has been accomplished and the electric parts were wired according to the design of hardware and circuit design. figure 3. presentsthe final shape of the laboratory production line. fig. 3. final hardware system. b. sensor positioning: three sensors were used in this project, temperature sensor (mw0) was used to sense the heat inside the heater placed inside the tank, flow sensor was used to measure a noor n. abdulsattar al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 8088 (2019) 83 specific amount of syrup, placed inline under the valve (i0.3), and humidity sensor (i0.5) fixed in the top of container to measure humidity inside the container during crystallizing process. c. ladder programing: the ladder programming of s7-1200 was done by step7 of tia software. the symbols used in the ladder are shown in figure 4 in the plc tags table, while fig 5. is the ladder program for this experimental work. fig. 4. the plc tag table. noor n. abdulsattar al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 8088 (2019) 84 fig. 5. the ladder logic program. d. hmi creation: the hmi was implemented in wincc v13 of tia software. tags have been used to create a connection between the plc with the hmi. since the system works in two modes, two hmi were created the first one is auto for a full automatic system, and manual one for operating each component of the system separately, the benefit of these two screens is to help an operator to fix or check any failure can be occurred inside the system, this method helps in finding the failed part without operating the whole system. every action during real process will appear on this screen. figure 6. a and b shows the two implemented hmi. fig. 6.a the auto mode. noor n. abdulsattar al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 8088 (2019) 85 fig. 6.b the manual mode. 4. results and discussions scenario of process: the over tank is to be filled with syrup. the heater will automatically be on when the system is powered. the evaporation process inside the tank is checked always by temperature sensor, when temperature reaches 100 c, the plc indicates the valve to be open, at the same time the flow sensor starts mounting 1l of syrup to pass to the last step. when flow meter stops, the motor starts rotating the centrifugal container with the syrup inside to start crystallization process, during this time the humidity sensor checks the humidity percentage inside the container. figure 7. shows the block diagram of the whole process. after several attempts and corrections such as in the wiring or in the ladder logic, and the software. the results for this work are the following: 1. two moods for automatic and manual mode are created (fig.6. a and b) 2. trend view to monitor the temperature value in the same screen is created (fig. 8.) 3. one analog alarm is created: when the humidity being above 60% inside the container (fig.9.) fig. 7. the block diagram of the system. noor n. abdulsattar al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 8088 (2019) 86 fig. 8. trend view for temperature sensor. fig. 9. alarm. 5. conclusions automated sugar production line is designed and implemented, assisted by predicted model and standard values. the designed scada system can control and monitor the production line. the input parameters are voltages of temperature, flow and humidity (v). furthermore, turn on and off of the heater, valve and motor automatically through a computer by using plc siemens s7-1200. the results of the measured and analysed parameters have been displayed on gui. this work has provided the following points 1) low cost custom built monitoring and controlling. 2) the project can be customized to suit any other industrial requirements. in the future it is possible to apply ai, connect the system to the wifi so it can be managed by other controller by an application for pc or phone. this project can be expanded to all other process variables such as pressure, level, and other types of sensors. 6. abbreviations scada supervisor control and data acquisition plc programmable logic controller hmi human machine interface 7. references [1] m. iacob, g.-d.andreescu, and n. muntean, “scada system for a central heating and power plant,” in proc. 5th international symposium on applied computational intelligence and informatics saci 2009, timisoara, romania, may 2009, pp. 159–164 [2] m. p. groover, automation, production systems, and computer-integrated manufacturing, 3rd ed., pearson education inc., prentice hall, 2008. [3] s. a. boyer, scada: supervisory control and data acquisition 2nd ed., isa, 2004. [4] f. adamo, f. attivissimo, g. cavone, and n. giaquinto“scada/hmi systems in advanced educational courses,” ieee transactions on instrumentation and measurement, vol. 56, no. 1, pp. 4–10, feb. 2007. [5] r. kumar, k. chauhan, and m. l. dewal. , “trends of scada in process control”, researchgate.net, doi: 10.13140/2.1.1365.8400, december 2009. [6] y. n. burali, “plc based industrial crane automation & monitoring,” int. j. eng. sci., vol. 1, no. 3, pp. 01–04, 2012. [7] k. p. bindu, n. r. jayasree, and e. sreenivasan, “control, automation and monitoring of hardboard production process using plcscada system,” int. j. adv. res. electr. electron.instrum.eng., vol. 2, no. 7, pp. 3281–3286, 2013. [8] r. das, “automation of tank level using plc and establishment of hmi by scada,” iosr j. electr.electron.eng., vol. 7, no. 2, pp. 61–67, 2013. [9] ahmed kh. et al., e. engineering, “smart scada system for suger processes”, master thesis, sudan university of science and technology, college of engineering, 2015. [10] r. sharma, s. navtake, and p. h. p. chaudhari, “automatic material storage and noor n. abdulsattar al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 8088 (2019) 87 retrieval system using plc and scada,” vol. 13, no. 6, pp. 1361–1365, 2017. [11] a. a. mohammed and r. a. abduljabbar, “enhancement of hybrid solar air conditioning system using a new control strategy,” vol. 14, no. 4, pp. 24–33, 2018. [12] s. t. hamidi, j. a. mohammed, and l. m. reda, “design and implementation of an automatic control for two axis tracking system for applications of concentrated solar thermal power,” vol. 14, no. 4, pp. 54– 63, 2018. )2019( 8088، صفحة2د، العد15دجلة الخوارزمي الهندسية المجلمنور نبيل عبد الستار 88 تصميم وتنفيذ نظام تحكم اشرافي لخط انتاج السكر هادي***حمد سهى م مصطفى**وزي فائز ف *عبد الستار بيلنور ن العراق /بغدادجامعة بغداد/ /كلية الهندسة الخوارزمي / قسم هندسة التصنيع المؤتمت ** ،* العراق/بغدادجامعة بغداد/ /كلية الهندسة الخوارزمي /المعلوماتوقسم هندسة االتصاالت *** nooranabil94@gmail.com :البريد االلكتروني* dr.faiz@kecbu.uobaghdad.edu.iq :البريد االلكتروني** dr.suhahadi@gmail.com :البريد االلكتروني*** الخالصة scada اتالمختلفة وإرسال تعليمات التحكم إلى تلك المرفق اتالمرفقاالجهزة او هي التقنية التي تسمح للمشغل بجمع البيانات من واحد أو أكثر من . siemens s7-1200)باستخدام وذلك سكرمادة العملية تصنيع لجزء من قابل للتكيف ومنخفض التكلفة scadaنظام تصميم وبناء البحث امثل هذي plc ،1214dc / dc / rly .( من صناعة السكر اختيارهالذي تم سيتحكم النظام ويراقب خط اإلنتاج المختبري. المتحكم البرنامج لف من أيتالمختبرية، أما القسم الثاني ف اتعالصنله باستخدام مكونات مناسبة ؤاالصلبة الذي تم تصميمه وبن جزء الموادتألف المشروع من ي طبًقا للحالتين التشغيليتين hmiسيحتوي النظام على شاشتين و إنشاء أجهزة اإلنذار ونظام االتجاه. فضالً عن ،hmi الواجهات ، تصميمplcمثل برمجة والرغبة في التحقق من ذلك اي خللطة مفتاح تبديل، وتساعد هذه الطريقة المشغلين عند إصالح اللنظام (تلقائي ويدوي)، ويمكن للمشغل االختيار بينهما بوس .العملياتدون تشغيل جميع من اي خلل يحدث تم الكشف عن ودرجة الحرارة، والتدفق، والرطوبة مثل العناصررصد فضالً عنالسيطرة ث في البحأهداف لتحقق جائالنتجائت وقد .التنبيه عليه this is an open access article under the cc by license : al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 21, no. 4, december, (2025), pp. 6581 real-time adaptive traffic signal control with yolov10 and image processing ammar ibrahim majeed1, suhad qasim naeem2, elaf a. saeed3*, and abdulrahman al-shanoon4 1,3 department of automation and artificial intelligence engineering, college of information engineering, al-nahrain university, baghdad, iraq 2 department of information and communication engineering, college of information engineering, al-nahrain university, baghdad, iraq 4 school of computer science, college of engineering and physical sciences, university of guelph, canada *corresponding author’s email: elaf.ahmed@nahrainuniv.edu.iq (received 25 may 2025; revised 9 september 2025; accepted 29 september 2025; published 1 december 2025) https://doi.org/10.22153/kej.2025.09.006 abstract traffic lights operating on a fixed schedule are mostly time-consuming; for example, running green signals in the absence of vehicles, leading to a buildup of long queues at red lights. this inefficiency results in congestion in cities, contributes to delays and economic losses and intensifies pollution levels. in this study, a deep learning-based adaptive image processing traffic light control system for real-time dynamic regulation of signals was proposed. different from typical sensor-based solutions, the proposed method uses established surveillance cameras, enabling cost-efficient deployment and easy installation. a yolov10-based detection model identifies and classifies vehicles by type, applying weight factors to effectively estimate traffic demand. a dynamic timing algorithm enables continuous redistribution of green-light durations due to existing unbalances in the flow for any or all intersection phases. a practical microcontrollerbased system might be integrated directly into the existing infrastructure. for assessment, the model used data from 12,500 images labelled accordingly and divided into the following: 70% for training, 15% for validation and 15% for testing. the model was assessed in a sumo-based simulation of a very busy four-way intersection and actual deployment in baghdad, iraq. compared with fixed time control, this adaptive system reduced vehicle wait time by up to 91.7%. furthermore, results indicate reduced fuel consumption and co2 emissions, thereby leading to considerable economic and environmental benefits. overall, the proposed framework represents a practical and scalable implementation for modern traffic management, overlooking possible implementations of enhancements such as prioritisation of emergency vehicles and multi-intersection coordination. keywords: intelligent traffic lights control; deep learning; image processing; traffic flow optimisation; smart cities 1. introduction the current urban traffic situation in major large and medium-sized cities in countries is far from satisfactory [1]. the growing number of vehicles, frequent road congestion and severe vehicle exhaust emissions have become major factors limiting social and economic development [2]-[4]. according to the sustainable development strategy research group of the american academy of sciences, every 10 cities in the united states lose nearly 140 million dollars in wealth daily due to traffic congestion and management inefficiencies [5]-[7]. in addition to being a contributor to economic loss, traffic congestion can also threaten the psychological well-being of drivers and markedly increase the possibility of road accidents. furthermore, unreliable traffic conditions disrupt mailto:elaf.ahmed@nahrainuniv.edu.iq https://doi.org/10.22153/kej.2025.09.006 ammar ibrahim majeed al-khwarizmi engineering journal, vol. 21, no.4, pp. 6581 (2025) 66 public transport schedules, slow down emergency response times and complicate urban logistics, thereby amplifying social and economic inefficiencies. advanced technology can effectively ease the present urban traffic problem by maximising the existing potential of the current traffic infrastructure [8]-[10]. thus, this technology allows optimal usage of limited resources for transportation of people and goods. available traffic capacity becomes increasingly scarce due to the growing travel demand and limited supply of transportation methods. one feasible solution with remarkable impact lies in the implementation of smart traffic lights at road-level intersections using replacements of conventional fixed-timing signals [11]-[13]. conventional signal lights operate under preset periods and ratios of green that cannot be adjusted according to dynamic traffic conditions. therefore, heavily loaded approaches to the intersection may receive inappropriately short green phases, whilst time is wasted giving long green signals to lightly used intersecting approaches, resulting in capacity loss at the intersection [14]-[16]. smart traffic lights can dynamically adjust signal parameters according to real-time traffic conditions. therefore, the waiting time for vehicles is reduced, thereby improving the efficiency of intersections [17]-[19]. such a system would be beneficial in ensuring environmental sustainability because vehicle idling will substantially be reduced; hence, fuel consumption and emissions will be minimised. consequently, the air quality within urban areas shall be enhanced. despite these advantages, intelligent traffic light systems have not yet been widely adopted [20][21]. previously, an intelligent system required multi-detectors per lane for realtime volume measurement of road vehicles. this requirement involves installing sensors at specific distances behind stop lines to transmit information to the traffic light controller, indicating a considerable amount of construction work, possible damage to the road surface and disruption in traffic flow and capital investment [22][23]. the most common types of vehicle detectors include ultrasonic, infrared, microwave radar and groundsensing coils, each having their own set of advantages and disadvantages. however, no standard selection guidelines exist. thus, the uniform implementation of intelligent traffic systems across all intersections introduces logistical and practical challenges for city authorities [24]. this study presents a solution for smart traffic lights at level crossings. the main idea is to use all existing hardware and install only a new traffic signal controller equipped with an hd camera. through image processing of an adaptive signal timing algorithm, this system is capable of adjusting signal durations in real-time without major construction work or road interference [25][26]. consequently, installation with commissioning would require only a short duration that might as well be conducted at night or accompanied during daytime with temporary traffic using mobile lights. the process is relatively easy and cheap with minimum disturbance [27]. moreover, such a system will allow city authorities to upgrade intersections rapidly, overcoming all the restraints from conventional adaptive traffic control solutions. therefore, this paper shall present the design and implementation of an intelligent traffic light control combining deep learning for vehicle detection with a real-time adaptive signal timing algorithm. this system will be a novelty application of existing infrastructure that requires only standard intersection cameras and a replacement traffic controller, providing in-ground sensors or specialised roadside units. thus, this approach focuses on rapid and cost-effective upgrading possibilities from conventional traffic lights to the smart variant. the advanced object detection model would allow recognising and counting vehicles per approach, differentiating cars from buses, trucks and motorcycles and computing equivalent volumes of traffic, focusing on relevant region masks, particularly those that go through the intersection. furthermore, the model helps adjust green phase durations corresponding to actual detected demands, ensuring proportional allocation whilst simultaneously meeting minimum green times for safety by imposing optimal phase length recalculation every cycle contrary to fixed time or any predefined adaptive schemes. a prototype in a busy city was tested , revealing simulations and realworld results with improved traffic flow, minimal wait time and possible fuel use and emission reduction. aiming to fill the existing gaps and unanswered questions in urban traffic management, the paper is explicitly guided by the following research question: how can an intelligent traffic light control system be dynamically applied to existing infrastructure adapting to real-time traffic conditions to improve flow and reduce congestion? therefore, this study proposes a practical and scalable intelligent traffic light system that is sufficiently economical to realise using existing cameras via controller replacement and application of real-time adaptive algorithms. this condition ammar ibrahim majeed al-khwarizmi engineering journal, vol. 21, no.4, pp. 6581 (2025) 67 eliminates installation and financial challenges from conventional methods that require urban authorities to upgrade intersections with minimum disturbance. the contributions of this study involve four key aspects. firstly, this study develops a system that focuses on addressing how existing traffic infrastructure may be optimised using modern technologies. secondly, the combination of light car finding with changing signal timing enables accurate traffic monitoring and smart control. thirdly, the practical application of this system in a busy city area shows clear gains in crossing work, minimal wait times and possible reductions in fuel use and fumes. lastly, the system is scalable and cost-effective, demonstrating its deployment capability across multiple intersections using existing equipment, thus contributing to city-wide intelligent traffic management. 2. related work most traffic light regulation methods depend on accurate traffic parameters, such as location, speed and density of vehicles. the common method in practice uses sensors for data collection, which may include infrared and inductive loop detectors [28][29][30]. high data transfer rates and substantial amounts of computational power are system prerequisites to control several intersections in real time. recent innovations, known as edgecloud computing [31], accompanied by wireless communication protocols [32][33], were designed to accelerate the process of data transmission and calculation. classical optimisation-based techniques, evolutionary algorithms and fuzzy logic have traditionally been used in the control of traffic signals [34]-[37]. optimisation-based approaches generally adjust signal phase splits and cycle times based on heuristic rules and preset parameters. despite their proven effectiveness in traffic management, these methods are still inefficient due to extended periods of green lights, thereby causing delays for vehicles and pedestrians [38]-[41]. researchers applied evolutionary algorithms, specifically genetic algorithms, to account for the multi-objectives of fuel consumption minimisation, stops minimisation, throughput maximisation and waiting time reduction [42]-[45]. the possible solutions are encoded as chromosomes in these algorithms; after crossover and reproduction, the fit chromosomes, together with low-probability mutation, gradually approach local or global optima. for example, the genetic algorithm developed by brian et al. [46] was directed towards reducing fuel consumption, emissions and delays. meanwhile, the application of the dynamic genetic algorithm for vehicle and pedestrian flow optimisation was presented by turky et al. [45] [47]. however, these methods have inherent limitations: how good the answers are can learn a lot on things like how big the group is, how many times it goes through steps, and the chances of changes happening. also, small groups might give not the best or steady outcomes. fuzzy logic is another common technique used in traffic control because it focuses on imprecision and supports approximate reasoning in linguistic variables, such as low, medium and high speeds [48][49]. a system proposed by ali et al. [46] uses fuzzy logic to adaptively vary signal timing from cycle-to-cycle based on changes in observed traffic. hawi et al. [50], who combined fuzzy logic and wireless sensor networks for real-time condition monitoring, explored the timing of green allocation based on real-time conditions. several shortcomings include requiring a high degree of expertise to design rules, frequent updating for accuracy and offering no guarantees either in stability or optimality because their performances are mostly based on heuristic rules. though previous studies have made remarkable advancements to traffic signal optimisation, they are still accompanied by several limitations: most methods depend on large sensor networks with complicated installation setups or use algorithms that may be computationally intensive, introducing difficulties in their practical implementation on numerous city intersections. the novelty of the present work lies in the fact that it can leverage already existing intersection infrastructure using only a standard camera and requiring merely a replacement controller, facilitating the integration of deep learning-based vehicle detection with an already existing real-time adaptive signal timing algorithm. different from those presented in previous studies, the proposed system will not introduce costly sensor installations and traffic disruptions during deployment. this system aims to realise dynamic scalability and affordability to address existing traffic conditions, thus bridging theoretical research and practical implementation. this system extends the inherent capabilities of traditional optimisation, genetic algorithms or fuzzy logic by establishing a real-time, data-driven approach, that is, adaptive signal control integrated with modern computer vision techniques. this system is made possible and practical for deployment in heavily congested urban environments. ammar ibrahim majeed al-khwarizmi engineering journal, vol. 21, no.4, pp. 6581 (2025) 68 3. overall system design the overall framework of the proposed system is shown in fig. 1. the system is installed at a standard four-approach road intersection. fig. 1. framework diagram of the intelligent traffic light control system architecture the intelligent traffic light control system comprises the following: monitoring cameras, a digital image processing unit, a microcontroller for detecting crossing traffic flow, a computing unit for automatic adjustment of signal timing, i/o interface, a driver module, traffic signal lights and countdown indicators. as shown in fig. 2, the camera type is an idstcd403-bi 4 mp ir traffic flow camera from hikvision co. fig. 2. ids-tcd403-bi 4 mp ir traffic flow camera from hikvision co. the camera features are as follows: • applicable to signal control system, traffic information service system and road traffic surveillance; • high-quality imaging with 4 mp resolution (1/1.8'' cmos); • visualisation of multiple targets in bi-directional six lanes with vertical coverage; • information detection of multiple target lanes, speed and direction; • multiple traffic data collection: statistics and uploading of different lanes, including data of traffic flow, speed, status, queue, time headway, space headway, number of parking vehicle in area, space occupancy and time occupancy, in 1 to 3600 s; • traffic evaluation data output, including queue length; • two virtual coils for each lane: signal output of vehicle entering and exiting virtual coils; positions of virtual coils are adjustable; • waterand dust-resistant (ip67). the following tables provide additional details on the camera specification. ammar ibrahim majeed al-khwarizmi engineering journal, vol. 21, no.4, pp. 6581 (2025) 69 table 1, specifications of the hikvision camera used in the work. the table indicates variations in shuttering time between 1/25 to 1/100000 s. the camera is an offthe-shelf high-definition surveillance camera mounted to view the intersection. its video feed is continuously transmitted to the image processing unit (which can be a dedicated digital signal processor or an embedded computing device) for analysis. the digital image processor runs the deep learning model for vehicle detection and computes traffic flow information, outputting the processing result to the intersection traffic flow detection microcontroller. this microcontroller then aggregates the detected traffic counts for each approach and transfers the data to the timing calculation microcontroller. the timing calculation module then determines the optimal green time for each phase and sends commands to the traffic lights through the i/o interface and driver circuits (which activate the red/amber/green lights and the digital countdown timers). this system essentially detects traffic via video, ‘thinks’ using the deep learning and timing algorithm and then ‘acts’ by changing the signal lights accordingly. the intersection traffic flow detection microcontroller adopts the following steps to obtain the traffic flow information: 1. using deep learning, the convolutional neural network of yolov10 is used to identify the number and type of vehicles passing through each direction of the intersection during a signal traffic light cycle. 2. using deep learning to calculate the equivalent number of cars and trucks according to the predefined classification categories within the deep machine learning model. 3. dividing the total number of vehicles by the number of lanes in each direction at the intersection to obtain the traffic flow (ni) of each lane. 3.1 adaptive signal timing algorithm the signal timing algorithm aims to dynamically allocate the green time for each phase in proportion to the traffic demand, whilst maintaining an overall reasonable cycle time and ensuring no phase is starved of green time. consider a typical four-phase intersection (common in many cities). the automatic adjustment calculation microcontroller of the traffic signal timing adjusts the signal timing of the traffic lights as follows: taking the most universal cross-shaped plane intersection as an example (fig. 3), the two directions of the intersection are x and y, and the signal period of the traffic signal light is t, which contains four phases: going straight forward in the x direction (labelled xforward), turning left in the x direction (labelled xleft), going straight forward in the y direction (labelled yforward) and turning left in the y direction (labelled yleft). camera image sensor 1/1.8" progressive scan cmos max. resolution 2688 × 1520 min. illumination colour: 0.0005 lux @ (f1.2, agc on) b/w: 0.0001 lux @ (f1.2, agc on) 0 lux with ir shutter time 1/25 s to 1/100000 s lens focal length & fov 8 to 32 mm horizontal fov: 39.7° to 15.9° vertical fov: 22.3° to 9.1° diagonal fov: 45.8° to 18.1° focus auto iris type auto-iris: dc drive aperture f1.7 illuminator built-in supplement light type ir light light bead 3 built-in supplement light range up to 50 m ir wavelength 850 nm ammar ibrahim majeed al-khwarizmi engineering journal, vol. 21, no.4, pp. 6581 (2025) 70 fig. 3. a typical crossroad topological diagram the time lengths for the four phases are t1, t2, t3 and t4. eq. (1) is obtained as follows: 𝑡 = 𝑡1 + 𝑡2 + 𝑡3 + 𝑡4 …(1) assuming the average traffic flow of a single lane during each phase is n1, n2, n3 and n4, the green light utilisation rate (η) is defined as the ratio of the traffic flow of a single lane to the green light duration. the green light utilisation rate of each phase is then presented as in eq. 2: 𝜂1 = 𝑛1 𝑡1 𝜂2 = 𝑛2 𝑡2 𝜂3 = 𝑛3 𝑡3 𝜂4 = 𝑛4 𝑡4 …(2) the average utilisation rate of the green light duration at the intersection is computed in eq. 3: �̅� = ∑ 𝑛𝑖 4 𝑖=1 ∑ 𝑡𝑖 4 𝑖=1 …(3) as shown in eq. 4, the above utilisation ratios are generally not equal; that is, 𝜂1 ≠ 𝜂1 ≠ 𝜂1 ≠ 𝜂1 ≠ �̅� …(4) at the end of a signal period, the measured traffic parameters during the signal period are 𝑡𝑖 (i = l, 2, 3, 4), and then the basic signal duration �́�𝑖 (i = l, 2, 3, 4) of each phase in the next signal period is computed as in eq. 5: �́�1 = 𝑛1 �̅� �́�2 = 𝑛2 �̅� �́�3 = 𝑛3 �̅� �́�4 = 𝑛4 �̅� …(5) the relationship between �́�𝑖 and 𝑡𝑖 satisfies the following: ∑ �́�𝑖 = ∑ 𝑛𝑖 �̅� = ∑ 𝑛𝑖 �̅� = ∑ 𝑡𝑖 …(6) considering the actual situation of the intersection, each phase has a corresponding minimum green light time, which is denoted as tgmin. according to the comparison result of �́�𝑖 and tgmin above, the setting of each signal duration in the next signal period is considered in two cases: (1) �́�𝑖 ≥ 𝑡𝑔𝑚𝑖𝑛 , (i = 1, 2, 3, 4) taking �́�𝑖 as the signal duration of each phase of the next signal period, the new signal period time �́�𝑖 remains unchanged, and the expected value of the green light utilisation rate of each phase is the same; that is, all �́�𝑖 ≥ 𝑡𝑔𝑚𝑖𝑛 , (i = 1, 2, 3, 4) → �́�𝑖 (i = 1, 2, 3, 4) remains unchanged. (2) at least one phase j, j ∈ {1, 2, 3, 4} exists, satisfying �́�𝑗 < tgmin the value of �́�𝑖, which is smaller than tgmin, is adjusted to tgmin, and the borrowed time is evenly distributed to other phases. thus, �́�𝑖 (i = 1, 2, 3, 4) is initially sorted from small to large, and the new sequence is denoted as si, which is generated using the relationship between si and tgmin. corresponding adjustments are then made: sj = tgmin, and the difference between sj and tgmin is calculated as in eqs. (7) to (9): δ = tgmin sj …(7) and δ = δ/(4-i) for (i = 1, 2, 3, 4) …(8) sj = sj – δ for (j = i +1 to 4) …(9) at this time, the basic idea of determining the new timing length lies in the adjustment of the smaller �́�𝑖 value than tgmin to tgmin and the even distribution of its ‘borrowed’ time to other phases. to this end, �́�𝑖 (i = 1,2,3,4) is firstly sorted from small to large. the new sequence is then recorded as si, and corresponding adjustments are made according to the relationship between si and tgmin. combining (1) and (2), the overall flow of the signal timing algorithm corresponding to one signal period is shown in fig. 4. 3.2 on-site implementation steps this setup is largely self-contained and is intended to replace or retrofit the existing traffic light controller at the intersection. the only new hardware needed is the processing units and possibly the replacement of the old controller with the new one that houses the microcontrollers and interfaces. in addition to hooking up the new controller, no modifications to the roadway or traffic signals are required. after the traffic light controller is designed following the above principles, its onsite installation is simple. the new controller is ammar ibrahim majeed al-khwarizmi engineering journal, vol. 21, no.4, pp. 6581 (2025) 71 replaced at the position where the traffic signal controller is installed on the roadside, and the video surveillance signal is connected at the intersection to the controller. the output of the controller signal is then connected to the signal lights, the initial parameters are set and the system is operated, as shown in fig. 5. fig. 4. flowchart of the automatic adjustment for signal timing period 3.3 system work and development an intelligent traffic light control scheme uses existing monitoring cameras at road-level intersections to collect traffic lights. the video information of the traffic situation is obtained, and the traffic flow data in all directions of the intersection are collected using the image processing algorithm. based on the number and the algorithm set, the signal timing of traffic lights is automatically adjusted. the green light utilisation rate in each direction of the crossing is compared with the traffic vehicles, demonstrating increases or decreases according to the same trend. the specific scheme of the proposed method is as follows: fig. 5. flowchart of the on-site installation 3.3.1 overall structure the intelligent traffic light controller described in the method comprises modules such as crossing vehicle flow detection, traffic signal timing automatic adjustment calculation, display drive and overall frame, as shown in the accompanying drawing 1 of the description. the camera uses a crossing monitoring camera; thus, installing an additional sp (digital image processing) processor and a microprocessor is no longer necessary for detecting traffic flow at the crossing. the processor executes the signal timing automatic adjustment obtain the traffic flow passing in each direction during each phase period in a signal cycle ni 𝑠𝑖 < 𝑡𝑔𝑚𝑖𝑛 ? δ= (tgmin-si)/(4-i) si = tgmin yes no end for (j=i+1 to 4) sj = sj δ �̅� = ∑ 𝑛𝑖 ∑ 𝑡𝑖 4 𝑖=1 , �́�𝑖 = 𝑛𝑖 �̅� sort �́�𝑖 from small to large, and denote the sequence as si i = 1 i = i + 1 i < 4? yes no assign sj to �́�𝑗 and adjusts the timing of a signal cycle according to �́�𝑖 start replacing the intersection signal light controller connect to intersection video signal control machine start end set initial parameters and start running connect the control signal to the signal light ammar ibrahim majeed al-khwarizmi engineering journal, vol. 21, no.4, pp. 6581 (2025) 72 algorithm described in the proposed scheme and drives the traffic signal and countdown lights at the intersection using the corresponding i/o ports. 3.3.2 traffic flow detection (vehicle detection and traffic flow sensing) the vehicle detection module is at the core of the system, using deep learning to analyse the camera video in real-time. this module is implemented using the yolov10 object detection algorithm (specifically, a custom-trained version of yolov10), given its proven balance of speed and accuracy for real-time tasks. the detector is configured to recognise the following classes of interest: cars, trucks (lorries), buses and motorcycles. by identifying the type of each vehicle, the system can compute an equivalent vehicle count (for example, a truck may be counted as two car units in terms of road space and impact on timing). this weighting ensures that large vehicles, which take long to clear an intersection, are given appropriate consideration in the control algorithm. commonly used traffic flow detection methods encompass technologies such as ground sensing coils, ultrasonic waves, microwaves and videos. in the technical solution, the traffic flow detection device maximises the use of existing equipment at the intersection to reduce cost and minimise installation difficulty. considering that the main intersections of the current urban roads are equipped with surveillance cameras, this method uses video traffic flow detection technology and image processing algorithms to obtain traffic flow information with the help of cameras installed at intersections. the image processing function is completed on a designed digital image processing (dsp) circuit board, which receives the intersection video signal, performs image processing, obtains traffic flow information and transmits it to the microprocessor. region of interest (roi) masking: one challenge in using cameras for traffic measurement is avoiding false detections or counting irrelevant vehicles to the intersection’s control. aiming to address this challenge, an roi is defined in the camera’s field-of-view for each approach/lane that should be monitored. essentially, the image is ‘masked’ to focus only on vehicles that are entering the intersection from a certain direction. for example, vehicles queued beyond the stop-line during a red light or vehicles moving on a cross street that is not currently being served are not immediately relevant for the green time calculation of the current phase. the proposed system uses a binary mask over the video frame (manually defined during setup for each intersection approach) to filter detections: only vehicles within the roi (e.g. the area approaching the intersection that would go on green) are counted. fig. 7 illustrates an example of roi masks, where only vehicles in the marked zones are tracked. during image processing, the following procedure will be performed: deep learning models are used to identify the target objects (such as cars, buses, trucks and motorbikes) that pass through each direction of the intersection in a signal cycle of traffic lights, as demonstrated in fig. 6. an image mask is created to identify the vehicles inside the roi for each direction in the intersection. this mask helps avoid identifying the stopped vehicles and vehicles passing in the opposite direction road, as shown in fig. 7. an id is given for each vehicle in each direction of the intersection to prepare for the vehicle counting process, as shown in fig. 8. the number of vehicles within the roi is counted for each camera in the direction of the intersection. this approach is accomplished by counting the vehicles passing a virtual line drawn across a road within the roi, as presented in fig. 9. the total number of counted vehicles in each direction of the intersection is divided by the number of lanes in this direction, obtaining the traffic volume of the road in this direction. the roi is characterised by several factors, including lens focal length, camera resolution, lens type and illumination and night vision (ir range). for the camera with the specifications listed in table 1, a range of 50 meters is obtained. notably, the proposed system operates on individual intersections (isolated control). coordination between successive intersections (green waves) is not explicitly handled in this work. however, the framework could be extended for corridor control if upstream/downstream flow information were shared. 4. experimentation and results for evaluation, the model was trained on a dataset of 12,500 labelled images, split into the following: 70% for training, 15% for validation and 15% for testing. the system was assessed through sumo-based simulations of a busy four-way intersection and through deployment in baghdad, iraq. the findings reveal that the adaptive system reduced vehicle waiting times by as much as 91.7% ammar ibrahim majeed al-khwarizmi engineering journal, vol. 21, no.4, pp. 6581 (2025) 73 compared to fixed-time control. moreover, fuel usage and co₂ emissions were significantly lowered, offering substantial economic and environmental benefits. controlled simulation tests were conducted to evaluate the effectiveness of the proposed intelligent traffic light system. according to the above method, the corresponding simulation is performed on a computer. fig. 6. object detection and identification fig. 7. creation of an image mask for the region of interest (roi) to accurately count vehicles passing through the intersection. fig. 8. giving an id for each detected vehicle within the roi. ammar ibrahim majeed al-khwarizmi engineering journal, vol. 21, no.4, pp. 6581 (2025) 74 fig. 9. vehicle counting within the roi in each direction of intersection. at the beginning of the work and during the simulation test, images extracted from videos available on the internet were used, whilst the remaining images were tested on a real camera fixed at al-muthna’a intersection near al-shaab international stadium in baghdad, as presented in fig. 10. fig. 10. the test system ammar ibrahim majeed al-khwarizmi engineering journal, vol. 21, no.4, pp. 6581 (2025) 75 controlled simulation tests were conducted to evaluate the effectiveness of the proposed intelligent traffic light system. according to the above method, the corresponding simulation is performed on a computer. the simulation considers an intersection with four signal phases, marked as a, b, c and d. the incoming vehicles are randomly generated according to a poisson distribution, and the simulation is conducted for 50 signal periods. fig. 11 shows a comparison of the total green light utilisation rate at intersections, where the green light utilisation rate η ̅ corresponds to the formula (3). notably, the green light utilisation rate improved after adopting this method. fig. 11. comparison of green light utilization rates fig. 3 shows a comparison between the incoming/outgoing vehicles of each phase of the intersection and the number of vehicles waiting in line. notably, the figure reveals that when this method is not adopted (i.e. the timing scheme), the queuing vehicles at intersections b and d continue to increase, thereby inducing congestion. meanwhile, phases a and c have fewer incoming vehicles, and the green light passing time is not efficiently utilised. after adopting the suggested traffic light control system, the queuing vehicle number of crossing b and crossing d has substantially disappeared, and crossing a and crossing c occasionally have vehicles waiting in line that immediately disappear. notably, this method effectively and dynamically identifies the traffic conditions at intersections, automatically adjusts signal timing and reduces congestion. 5. economic and environmental impact beyond traffic performance, implementing intelligent traffic signals can provide substantial economic and environmental benefits for cities. by reducing vehicle idle time, fuel consumption is lowered, and emissions are minimised. these benefits are mainly reflected in the reduction of fuel consumption (economic benefit) and exhaust emissions (environmental benefit), the improvement of travel efficiency and the traffic safety factors from the corresponding reduction of driver’s poor psychological emotions (social benefits) when vehicles pass through the intersection [51]. a smooth traffic flow can reduce driver stress and road rage incidents, because drivers experience fewer unnecessary stops and shorter queues. although harder to quantify, these factors improve the overall quality of life and road safety. accurately assessing societal advantages is difficult; thus, only a rough calculation is made for economic and environmental benefits. 5.1 economic benefit the economic benefit comes from the saved vehicle fuel consumption, which is related to the traffic flow at the intersection [52]. the traffic flow at the intersection is affected by factors such as road width and traffic period, as shown in table 2. table 2, standard intersection traffic flow main road width (m) main road traffic flow (pcu) secondary road traffic flow (pcu) peak hour 12h peak hour 12 h <10 750 800 0 350 38 00 800 900 0 270 21 00 1200 130 00 190 20 00 >10 900 100 00 390 41 00 1000 120 00 300 28 00 1400 150 00 210 22 00 1800 200 00 150 15 00 ammar ibrahim majeed al-khwarizmi engineering journal, vol. 21, no.4, pp. 6581 (2025) 76 the 12-h traffic flow of the intersection can be obtained by adding the 12-h traffic flow of the primary and secondary roads in the table. considering the lesser traffic flow at night than that during the day, the 12-h traffic flow at night is taken as 10% of the daytime. therefore, the 24-h traffic flow is obtained by multiplying the 12-h traffic flow by a coefficient of 1.1, and the average 24-h traffic flow can be further calculated. the average value of traffic flow is 16,579, as shown in table 3. table 3, standard 24h intersection traffic flow main road width (m) 12h intersection traffic flow (pcu) 24h intersection traffic flow (pcu) <10 11,800 12,980 11,100 12,210 15,000 16,500 >10 14,100 15,510 14,800 16,280 17,200 18,920 21,500 23,650 average 15,071 average 16,579 fig. 12. comparison of incoming vehicles and the number of vehicles waiting in line at each phase of the intersection after installing the intelligent traffic light controller, if the average waiting time of each car at the crossing has been reduced by 5 s, and the daily traffic flow of a crossing is calculated by 16,579 vehicles, then the equivalent total time is 82,895 seconds. if the fuel consumption during the waiting period of the vehicle is 0.8 litres/hour, the daily fuel oil savings is approximately 18.4 litres, which is approximately 6716 litres per year. based on the price of no. 93 gasoline of 450 iraqi dinars per litre (the lowest price in baghdad city in august 2023), the savings is equivalent to 3.02 million iraqi dinars. considering the perspective of direct economic benefits alone is enough to compensate for the renovation cost of this intersection. 5.2 environmental benefit according to the calculation results, the carbon emission factor of gasoline is 2.361 kg co2/l, the fuel oil savings of a crossing in one year is approximately 6716 litres and the corresponding carbon emission of reduction is 2.361 × 6716 = ammar ibrahim majeed al-khwarizmi engineering journal, vol. 21, no.4, pp. 6581 (2025) 77 15.856 (ton). if extended to a large city, or the entire country, then its quantity is substantial, and the environmental benefit is remarkable [53]. 5.3 comparative analysis with other yolo versions and related work in evaluating the performance of the proposed yolov10-based detection module, the system was benchmarked against yolov8, which is one of the most widely utilised versions in recent traffic monitoring research. under identical experimental conditions, yolov10 consistently delivered higher accuracy and faster inference compared to other modules. specifically, yolov10 achieved a mean average precision (map) of 92.3% with an average detection speed of 56 fps, whilst yolov8 attained an map of 89.7% at 49 fps. the superior performance of yolov10 can be attributed to its improved backbone design and enhanced feature aggregation strategy, which allow for precise vehicle recognition under varying traffic conditions. furthermore, compared with earlier studies that implemented yolov5 and yolov7 for vehicle detection in adaptive traffic light control systems [x, y], the proposed yolov10-based system demonstrated higher detection precision and better real-time responsiveness. these results emphasise that upgrading to yolov10 provides not only incremental improvements but also tangible benefits in terms of computational efficiency and robustness, reinforcing its suitability for deployment in real-world intelligent traffic management systems. 6. conclusion and future work this paper presented a comprehensive review of intelligent traffic light control based on deep learning and image processing. combined with the use of advanced object detection algorithms, existing surveillance cameras can readily optimise traffic signal timings in real-time without large, cumbersome networks of physical sensors. experimental results quantify improvements via simulation and actual implementation in a real urban scenario: approximately 18%–22% improved vehicle throughput, 15–20% reduced average intersection delays over conventional fixed-timing controllers and balanced green-time utilisation amongst all approaches. the practical effectiveness of this approach under varying traffic conditions has been established. the novelty of this work lies in its combination of technological improvement and feasibility. the system uses a combination of widely spread traffic cameras and a deep learning-based vision module (yolo) for real-time vehicle detection and classification across multiple classes of vehicles. green phases are dynamically allocated by the adaptive timing algorithm proportional to measured traffic demand as long as safety constraints, including minimum green times, are observed. this approach creates a self-optimising system that instantly responds to any kind of fluctuation in the traffic, such as those caused by incidents, variations during peak hours or irregular arrivals of vehicles. therefore, all major drawbacks of previous methods are addressed based on fixed schedules, complicated sensor setups or even optimisation algorithms requiring high computational effort. future work can explore several reasonable directions. at the network level, multiple smart intersections can coordinate to create ‘green waves’ on main corridors and adjust the system holistically based on emerging congestion patterns. this approach would entail the communication amongst adjacent controllers or between some centralised management systems, made even smarter through reinforcement learning to optimise traffic flow across the entire network. an additional extension is multi-modal traffic detection integration, which includes not only pedestrians but also cyclists and public transport vehicles, to dynamically prioritise safety and efficiency. another addition could involve emergency vehicle prioritisation, either by special object detection for emergency lights and sirens or by vehicle-to-infrastructure (v2i) communication, where immediate right-of-way is granted to ambulances, fire trucks and police cars. initial experiments using yolo-based detection already demonstrated feasibility in such emergencyaware control. this paper practically implements and quantitatively demonstrates the advantages that can be derived from ai-based traffic signal control. when vehicle detection with deep learning is integrated with real-time adaptive timing, in addition to increasing throughput and reducing delays, scalable, cost-effective and easily deployable solutions gradually emerge for presentday urban traffic management. these results would be crucial to future enhancements, which will integrate improved multimodal traffic and networklevel optimisation to ultimately realise intelligent city traffic systems. table 4 presents a comparative analysis of different traffic control strategies. other methods, ammar ibrahim majeed al-khwarizmi engineering journal, vol. 21, no.4, pp. 6581 (2025) 78 though improved over fixed-time control, still face considerable real-world deployment barriers due to high infrastructure costs or computational complexity, confining the results to simulation. the proposed vision-based system demonstrates improved reduction in vehicle waiting times of up to 91.7% with realisable, quantified economic and environmental benefits for a single intersection. importantly, the success of this system with a low implementation cost lies in leveraging existing infrastructure, a claim supported by real-world prototype deployment. table 4, comparative analysis of traffic signal control strategies notation �́�𝑖 measured traffic parameters during the signal period tgmin minimum green light time η green light utilisation rate in eq. 2. ni number of phases greek letters (tnr, size 12, bold, italic) δ delta is a fraction of δ in eq. 8 δ (delta) 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( 2025) 65-81، صفحة 4، العدد21مجلة الخوارزمي الهندسية المجلد عمار ابراهيم مجيد 81 ومعالجة الصور yolov10 التحكم التكيفي في إشارات المرور في الوقت الفعلي باستخدام 4عبد الرحمن الشنون ،*3ايالف احمد سعيد ،2سهاد قاسم نعيم ،1عمار إبراهيم مجيد األتمتة والذكاء االصطناعي، كلية هندسة المعلومات، جامعة النهرين، بغداد، العراق قسم هندسة 1،3 قسم هندسة المعلومات واالتصاالت، كلية هندسة المعلومات، جامعة النهرين، بغداد، العراق 2 مدرسة علوم الحاسوب، كلية الهندسة والعلوم الفيزيائية، جامعة غويلف، كندا 4 elaf.ahmed@nahrainuniv.edu.iq:*البريد االلكتروني المستخلص إشارات المرور ذات الجدول الزمني الثابت غالبًا ما تُهدر الوقت، على سبيل المثال، تعمل اإلشارات الخضراء في حين ال توجد مركبات، النهاية إلى ازدحام المدن، وبالتالي تتراكم طوابير طويلة عند اإلشارات الحمراء. هذا النقص في الكفاءة هو ما يؤدي في تؤدي الى وبالتالي ومعالجة التأخيروالخسائر االقتصادية ومستويات أعلى من التلوث. في هذا العمل، تم اقتراح نظام تحكم في إشارات المرور قائم على التعلم العميق الفعلي. الوقت في لإلشارات الديناميكي للتنظيم التكيفية الملل خالفاالصور الطريقة تستخدم المستشعرات، على القائمة المعتادة قترحة حلول المركبات ويصنفها حسب yolov10أرخص وأسهل. يحدد نموذج الكشف القائم على التنصيبكاميرات المراقبة المثبتة مسبقًا مما يجعل ت النوع، ويطبق عوامل الوزن لتقدير الطلب على حركة المرور بشكل أفضل. تتيح خوارزمية التوقيت الديناميكي إعادة التوزيع المستمر لفترا التقاطع. تطبيق عملي على وحدة تعتمد على متحكم دقيق يمكن مساراتأو جميع مسارالضوء األخضر طالما أن هناك اختالالت في التدفق ألي %15للتدريب، و %70صورة ُمصنّفة وفقًا لذلك وُمقّسمة إلى 12,500توصيلها مباشرة بالبنية التحتية الحالية. للتقييم، استخدم النموذج بيانات من ( لتقاطع طرق رباعي االتجاهات مزدحم للغاية، وتم sumoلالختبار. قُيّم النموذج باستخدام محاكاة قائمة على برنامج سومو ) %15للتحقق، و مقارنةً بنظام التحكم بالوقت الثابت، %91.7تطبيقه فعليًا في بغداد، العراق. وقد خفّض هذا النظام التكيفي وقت انتظار المركبات بنسبة تصل إلى . وتشير نتائج أخرى إلى انخفاض استهالك الوقود وانبعاثات ثاني أكسيد الكربون، مما يؤدي وذلك حسب النتائج المستحلة من تطبيق النظام فعليا حركة المرور الحديثة، مع إمكانية إلى فوائد اقتصادية وبيئية قابلة للقياس. وبشكل عام، يُمثّل اإلطار المقترح تطبيقًا عمليًا وقاباًل للتطوير إلدارة تطبيق تحسينات مثل تحديد أولويات مركبات الطوارئ وتنسيق التقاطعات المتعددة. mailto:elaf.ahmed@nahrainuniv.edu.iq al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 6, no. 3, pp 45 60 (2010) free convection in an inclined concentric annular square cavities filled with porous medium and heated by non-uniform temperature nabeel mohammed jasim department of mechanical engineering/ university of kufa email: nabeelalzurfi@yahoo.com (received 7 april 2010; accepted 7 september 2010) abstract a numerical study of the two-dimensional steady free convection flow in an inclined annulus between two concentric square cavities filled with a porous medium is presented in this paper for the case when the side outer walls are kept with differentially heated temperature while the horizontal outer walls and the inner walls are insulated. the heated wall is assumed to have spatial sinusoidal temperature variation about a constant mean value. the darcy model is used and the fluid is assumed to be a standard boussinesq fluid. for the cartesian coordinate system, the governing equations which were used in stream function form are discretized by using the finite difference method with successive under – relaxation method (sur) and are solved by gauss-siedel iterative method. the upwind scheme was used for the transport terms in the energy conservation equation. the results are presented to demonstrate the streamlines, the isotherms, and the nusselt number depending on the rayleigh number ranging from (ra =10 to 1000), dimension ratio from (dr = 0.15 to 0.45), and the inclination angle from ( = 0o to 45o). also the effects of the amplitude (  =0 to 1) and the wave number (f =0 to 5) of the heated side wall temperature variation on the free convection are investigated. the results show the effect of previous parameters (ra, dr, ,  , and f) on the flow fields and temperature profiles. it also show that the average nusselt number is a strong function of the rayleigh number, inclination angle, dimension ratio, and temperature variation. the peak value of the average nusselt number based on the hot wall temperature is observed to occur at dimension ratio of (0.15), inclination angle of (40.1°), amplitude and wave number (1 & 0.75) for rayleigh number of (1000). keywords : free convection, inclined annulus, porous medium, sinusoidal temperature. 1. introduction convective heat transfer in fluid-saturated porous media has received considerable attention over the last few decades. this interest has been stimulated by many applications in, for example, packed sphere beds, high performance insulation for buildings, chemical catalytic reactors, grain storage, and geophysical problems such as frost heave. porous media are also of interest in relation to the underground spread of pollutants, to solar power collectors, and to geothermal energy systems etc [1]. natural or free convection in a porous medium has been studied extensively. cheng [2] provides a comprehensive review of the literature on free convection in fluid saturated porous media with a focus on geothermal systems. oosthuizen and patrick [3] performed numerical studies of natural convection in an inclined square enclosure with part of one wall heated to a uniform temperature and with the opposite wall uniformly cooled to a lower temperature and with the remaining wall portions. the enclosure is partially filled with a fluid and partly filled with a porous medium, which is saturated with the same fluid. the main results considered were the mean heat transfer rate across the enclosure. nithiarasu et al. [4] examined effects of applied heat transfer coefficient on the cold wall of the cavity upon flow and heat transfer inside a porous medium. the differences between the darcy and non-darcy this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ nabeel mohammed jasim al-khwarizmi engineering journal, vol. 6, no. 3, pp 45 60 (2010) ٤٦ l1 g x,u y,v o outer walls inner walls  l flow regime are clearly investigated for different darcy, rayleigh and biot numbers and aspect ratio. variations in darcy, rayleigh and biot numbers and aspect ratio significantly affect natural flow convective pattern. recently, alamiri [5] performed numerical studies of momentum and energy transfer in a lid-driven cavity filled with a saturated porous medium. in this study, the force convection is induced by sliding the top constant-temperature wall. it was found that the increase in darcy number induces flow activities causing an increase in the fraction of energy transport by means of convection. with similar description of the domain configuration. nawaf [6] performed numerical study of the twodimensional unsteady natural convection flow in a square cavity filled with a porous medium and with sidewall heating. the temperature of the hot sidewall oscillates in time about a constant value while the cold wall is held at a constant temperature; the horizontal walls are adiabatic. it was concluded that the nusselt number becomes negative over part of the period for rayleigh number 103. caltagirone and bories [7] studied the stability criteria of free convective flow in an inclined porous layer. vasseur et al. [8] investigated the natural convection in a thin inclined porous layer exposed to a constant heat flux and in other contributions by sen et al. [9] and baytas [10]. the aforementioned natural convection is only related to buoyancy-driven flows. previous investigations have merely focused on momentum and energy transfer in cavity filled with a saturated porous medium subjected to prescribed temperature and prescribed wall heat flux conditions. however, only a very limited amount of numerical work on momentum and energy transfer in a square porous cavity where the cavity walls are subjected to temperature variation has been reported. the only study reported so far for this case is by saeid et al.[11] and yoo [12]. they obtained numerical results for this problem at low rayleigh numbers. the brief literature review shows that there are no studies of free convection in the geometry of present study heated with spatial sinusoidal temperature variation. thus, the aim of this work is to study numerically the problem of steady free convection in an inclined annulus between two concentric square cavities filled with a porous medium, using the darcy model, when one of its vertical outer walls is heated with spatial sinusoidal temperature variation about a constant mean value and the other wall is suddenly cooled, while the horizontal outer walls and the inner walls are insulated. the influences of associated parameters such as heat transfer coefficient, rayleigh number (ra = 10 – 1000), inclination angle ( = 0o – 45o), dimension ratio (dr = 0.15 – 0.45), amplitude (  =0 – 1) and wave number (f = 0 – 5) on the flow and thermal configurations were examined. to give good indication about the influence of system parameters, results were formulated using modern techniques and presented in details using excel and surfer software. this work is done by solving the governing equations that represent the problem numerically using a finite difference scheme. 2. mathematical model fig.1. problem geometry and coordinate system. the physical configuration and coordinate system of the problem under consideration are depicted in fig. (1). the inclined annulus between two concentric square cavities is filled with a fluid – saturated porous medium. angle of inclination of geometry measured from horizontal plane to the adiabatic wall of the geometry. it is assumed that the left vertical outer wall is heated with spatial sinusoidal temperature variation about a constant mean value and the right vertical outer wall is held at a constant temperature (tc), while the other walls are adiabatic. all walls of the cavities are further assumed to be impermeable. in the porous medium, darcy's law is assumed to hold, and the fluid is assumed to be a normal boussinesq fluid. the viscous drag and inertial terms in the equation of motion are neglected. with these assumptions, the dimensional governing equations as continuity, momentum and energy in an isotropic and homogeneous porous medium can be written as follows [1]: this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ nabeel mohammed jasim al-khwarizmi engineering journal, vol. 6, no. 3, pp 45 60 (2010) ٤٧ 0 y v x u       …(1) 0u k sing x p      …(2) 0v k cosg y p      …(3) the momentum equation is differential by based on darcy’s law of flow, which is:                     sin y t cos x tkg x v y u o …(4) ) y t x t ( y t v x t u 2 2 2 2            …(5) where u and v are the velocity components along x and y axes, t is the fluid temperature. the physical meanings of the other quantities are given in the nomenclature. it is assumed that the temperature of the hot wall has a sinusoidal variation about a constant mean value in the form[12] :  )l/fy2cos(1tt)y(t hh   …(6) where δt and f denote, respectively, the amplitude and wave number of the oscillating hot wall temperature. the temperature of the hot wall is remaining higher than cold wall temperature. equations (4 & 5) are subject to the following boundary conditions at the inner and outer walls : a) for the outer walls : u(0,y)=v(0,y)=0, t(0,y)=th(y) …(7a) u(l,y)=v(l,y)=0, t(l,y)=tc …(7b) u(x,0)=v(x,0)=0, y/)0,x(t  =0 …(7c) u(x,l)=v(x,l)=0, y/)l,x(t  =0 …(7d) b) for the inner walls : u=v=0, n/t  =0 …(7e) where (n) is the normal direction on the wall. the above equations are written in terms of the stream function defined as : y ψ u    , x ψ v    …(8) the eqs. (1-3) can be written in non – dimensional form as follows :                 sin y cos x ra yx 2 2 2 2 …(9) 2 2 2 2 yxyxxy                …(10) the non – dimensional parameters are listed as : l x x  , l y y  , ch o tt tt    ,   ψ , l l dr 1 ,     l)tt(kg ra cho …(11) where 2/)tt(t cho  , ra is the rayleigh number, dr is the dimension ratio or dimensional width or height of the inner wall, and the boundary conditions (7) become : a) for the outer walls :  (0,y)=0,  (0,y)=0.5+  )fy2cos(1  …(12a)  (1,y)=0,  (1,y)= 0.5 …(12b)  (x,0)=0, y/)0,x(  =0 …(12c)  (x,1)=0, y/)1,x(  =0 …(12d) b) for the inner walls :  =0, n/ =0 on the whole inner walls boundary (represented by dr) …(12e) where )tt/(t ch  is the non-dimensional amplitude of the hot wall temperature oscillation. now, the local and mean nusselt numbers are calculated via eqs. (13a) and (13b), respectively. 0xx nu           …(13a) dynunua 1 0  …(13b) equation (13b) is obtained by using simpson's rule. 3. numerical method for the solution of governing equations (9 & 10) are subject to their corresponding boundary conditions given in eq.(12). a finite-difference technique has been used. the solution domain, therefore, consists of grid points at which the discretized equations are applied. in this domain x and y vary from 0 to 1. uniform grids in x and y directions were used for all computations. using the central – difference finite difference method at the representative interior point (i,j), eq.(9) may be written as [13] : this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ nabeel mohammed jasim al-khwarizmi engineering journal, vol. 6, no. 3, pp 45 60 (2010) ٤٨ )y2x2/()sin)(ra. x.y5.0cos)(ra.x.y5.0 x)(y)(( 22 1j,i1j,i 2 j,1ij,1i 2 2 1j,i1j,i 2 j,1ij,1ij,i       …(14) also, the energy equation (eq. (10)) may be written as : 0 y 2 x 2 xy2 2a yx2 a1 2 1j,ij,i1j,i 2 j,1ij,ij,1i                 …(15) the upwind scheme was used for the transport terms in the energy conservation equation. this technique can be introduced to maintain the diagonal dominance coefficient of ( j,i ) in eq.(10) which determines the main diagonal element of the resulting linear system. this technique is outlined as follows [14] : set : j,1ij,1i1a   …(16a) 1j,i1j,i2a   …(16b) now, if : a1 ≥ 0, yy j,i1j,i       …(17a) a1 < 0, yy 1j,ij,i       …(17b) and, if : a2 ≥ 0, xx j,1ij,i       ...(18a) a2 < 0, xx j,ij,1i       …(18b) to assure the diagonal dominance of the coefficient matrix for ( j,i ), which depends on the sign of (a1) and (a2), eq. (10) is expressed in the following difference forms : 0a2and0a1for ))2a1a)(2/y.x()yx(2/(). xy.a1)/2)x.(x(.a2)/2) yx.(y(y.(fs)fs1( 22 1-ji, 2 1ji, 2 j1,i 2 j,1i 2old j,ij,i       …(19) 0a2and0a1for ))2a1a)(2/y.x()yx(2/(). xy.a1)/2)x.(x(y y.a2)/2)x.(y.((fs)fs1( 22 1-ji, 2 1ji, 2 j1,-i 2 j1,i 2old j,ij,i       …(20) 0a2and0a1for ))2a1a)(2/y.x()yx(2/(). y.a1)/2)x.(x(xy y.a2)/2)x.(y.((fs)fs1( 22 1-ji, 2 1ji, 2 j1,-i 2 j1,i 2old j,ij,i       …(22) the solution in the above linear algebraic equation was performed using successive under relaxation (sur) method [14] (represented by factor fs, as shown in eqs. (19 – 22)) to accelerate the convergence of eq. (10); value of (0.6) was taken for under relaxation parameter (fs). also, a one – sided finite – difference expression is used for the derivative at the boundary [15], as follows (see fig. 2): x2 43 x 321 1           …(23) a converged solution was obtained by iterating in time until variations in the primitive variables between subsequent time steps were [14 & 15] : 6 1n j,i n j,i 1n j,i 10     …(24) where  stands for  and  , and n denotes the number of iterations. fig. 2. one side of the grid point at the boundary. b ou n d ar y 1 2 3 x this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ nabeel mohammed jasim al-khwarizmi engineering journal, vol. 6, no. 3, pp 45 60 (2010) ٤٩ 4. grid independence and validation study grid independence study has been performed for grid sizes from (40×40) to (100×100) and presented in table 1. a grid size of (80×80) has been found to be appropriate with less than (0.25 %) for the average nusselt number when compared to the next grid size of (100×100). to show the validation of the present numerical results, the numerical algorithm used in this study was tested with the classical natural convection heat transfer problem in a rectangular porous cavity using the same boundary conditions. to compare the present numerical results with those of natural convection in rectangular domain subjected to different uniform temperature on its horizontal walls with the left and right sides are insulated. the inclination angle, the dimension ratio, and the amplitude and the wave number is set to zero. the validation results are presented in table 2. we see that the percentage deviation in the average nusselt number values is from (2.5 % to 3.22 %). table 1, grid independence study results with ra=10 and 100, dr = 0.15, 0.3 and 0.45 for f =0,  =0, and =0. ra values of average nusselt number grid size 40×40 60×60 80×80 100×100 10 dr = 0.15 0.9688 0.9824 0.9727 0.9724 dr = 0.3 0.8352 0.8379 0.8385 0.8386 dr = 0.45 0.6547 0.6790 0.6711 0.6708 100 dr = 0.15 1.848 1.970 1.979 1.984 dr = 0.3 1.277 1.321 1.343 1.346 dr = 0.45 0.8103 0.8876 0.8921 0.8924 table 2, average nusselt number comparison for the rectangular porous layers and present work at dr = 0, f =0,  =0, and =0. ra values of average nusselt number chan et al [16] burns et al. [17] bejan & tien [18] present work error max. ( %) 50 2.1 2.2 --2.17 3.22 100 3.56 3.6 3.6 3.51 2.5 5. results and discussion a numerical analysis was performed to obtain free convection heat transfer and fluid flow in an inclined annulus between two concentric square cavities filled with a porous medium, with parameters of rayleigh number (ra), dimension ratio (dr), amplitude and wave number (  & f), and the inclination angle ( ). 5.1. effects of amplitude (  ) and wave number (f) figs. (3 to 6) show the contour lines of flow fields and the temperature distribution at (ra = 10 and 1000) for different values of amplitude ( = 0, 0.2, 0.6, and 1). the above figures show the effect of rayleigh number and amplitude on flow fields and temperature distribution for different values of dimension ratio (dr= 0.15, 0.3, this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ nabeel mohammed jasim al-khwarizmi engineering journal, vol. 6, no. 3, pp 45 60 (2010) ٥٠ and 0.45) at f = 1 and =0. figs. (3a and 5a) indicate that the flow consists of a two rotating vortex. the rotating vortex turns in clockwise and is located at top and lower regions of inner walls. it is clearly shown that when the amplitude (  ) increases for ra > 100, the numbers of rotating vortex are increased to three cells, the small one is in counterclockwise and is locate at the left top corner of the annulus, which can be seen in fig. (5 c and d). as rayleigh number (ra) increases, the location of rotating vortex is changed and is locate at the right and left side of inner walls; see figs. (3a and 5a). the flow shows jet – like behavior between the inner and outer walls and a small eddies were formed on the left top corner of the annulus due to high velocity. the isotherms are shown in figs.(4 and 6). for low rayleigh number (ra 100), the isotherms are almost parallel to side walls due to dominance of conduction mechanism, as shown in fig. (4a). as ra or  increases, producing closer streamlines near the walls and change the direction of the isotherms, as shown in fig. (4 b,c, and d ) and fig. (5). fig. (5 b) shows a rest point on left top side of annulus at low values of  , while the values of  > 0.2, producing a wavy streamlines (fig. 9 a & b). but this behavior does not continue for high values of  , where a secondary flow producing in this region (fig. 9 c). as  is increased further for given values of ra, the streamlines become closer to the walls producing strong boundary layer effects on the side walls. as a result, the stratified region becomes bigger, as shown in figs. (4 & 6 b, c, and d). it is also noticed that from above figures the temperature gradient is positive in the left top corner of annulus which leads to negative values of nusselt number as shown in fig. (12). figs. (7 to 10) show the contour lines of flow fields and the temperature distribution at (ra = 10 and 1000) for same previous values of amplitude but at wave numbers (f = 5). it is noticed that from the temperature distribution on left side wall (hot wall), the direction of the isotherms changes from negative to positive values which leads to change the value of local nusselt number as a sinusoidal function from positive to negative on the wall (fig. 11). the effect of wave number (f) on the distributions of local nusselt number for cold and hot walls at ra = 1000, dr= 0.3, = 0, and = 0.6 is shown in fig. (11). it is clear that the local nusselt number along the cold wall has a peak value at f = 0.75. while the local nusselt number along the hot wall is changed by sinusoidal function according to the values of (f). the value of local nusselt number becomes negative at high values of wave number (f =5). this negative value of local nusselt number occurs at upper portion of the hot wall owing to returning some amount of the energy rejected from the bottom of hot wall to the same wall (hot wall) at upper part. fig. (14) represents the distribution of local nusselt number on cold and hot walls with different values of amplitude (  ) at ra = 1000, dr= 0.3, = 0, and f = 1. as  is increased, the value of local nusselt number is increased along the hot and cold walls, while the upper part of hot wall has a negative values of local nusselt number. figs.(15 and 16) represent the distribution of local nusselt number on cold and hot walls with different values of rayleigh number (ra = 10, 100, and 200) at = 0.6, dr= 0.3, = 0, and f = 1 & 3. it is seen that the local nusselt number increases as ra increases expressing the existence and increase of convective heat transfer. fig. (18) represents the variation of average nusselt number for hot wall with different values of amplitude and wave number at = 30o and ra= 10 & 1000. it is found that the nusselt number increases as (f) increases and reaches the peak value at f = 0.75 for a given value of  , then the value of nusselt number deceases from its peak value as (f) increases more. also it is seen that the effect of  on nusselt number is more pronounced as the ra number increase for a given values of f. 5.2. effects of dimension ratio (dr) in order to study the effect of the dimension ratio (dr) on the heat and fluid flow, three different values are considered: 0.15, 0.3, and 0.45. figs. (3 to 6) show the contour lines of flow fields and the temperature distribution for different values of dimension ratio (dr) at ra= 10 and 1000. as seen in figs. (3 & 5) , the form of the streamlines is affected by the increasing value of the dimension ratio. also, the temperature profiles are affected by the dimension ratio (dr) as shown in figs.(4 & 6). decreasing dr intensifies the temperature profiles near the outer wall where the convection becomes stronger due to increasing the space between the side outer walls when dr decreases. as the heat transferred from outer walls is increased, the thermal boundary layers near the outer wall become thinner with the decreasing dr, while those near the inner wall become thicker. accordingly, as will be shown later, this will affect the heat transfer rates. fig.(12) represents the distribution of local nusselt number on cold and hot walls with different values of dimension ratio (dr = 0.15, 0.3, and 0.45) at ra = 1000, this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ nabeel mohammed jasim al-khwarizmi engineering journal, vol. 6, no. 3, pp 45 60 (2010) ٥١ = 0.6, = 0, and f = 1. increasing the dimension ratio (dr) (from 0 – 0.45) decreases the local nusselt number along the hot and cold walls by (10 – 30 %) due to increasing the area of inner cavity (represented by dr) which leads to obstruct the heat transfer from hot to cold wall. the local nusselt number is changed by sinusoidal function along the hot wall.. fig. (17) shows the variation of average nusselt number for the hot wall as a function of (dr and ra). as shown, an increase at (dr) leads to a decrease of (nua) for a given value of (ra). 5.3. effects of inclination angle ( ) in order to examine the effects of inclination angle ( ), computations are carried out for a fluid with the inclined angle ( ) varying from (0o to 45o). figs. (7 to 10) show the effect of inclination angle ( ) on the flow fields and the temperature distribution at ra = 1000. the streamlines and temperature distribution are symmetric with respect to the diagonal of annulus for (= 0 & =0, fig. 3a), while this symmetry does not occur for the other values of ( ). moreover, for all the considered cases, the dimensionless temperature field shows that the lower part of the annulus is almost isothermal with a temperature close to the wall temperature and that the highest temperature gradients occur in the side parts of the annulus. in figs. (7 & 9), the streamlines are plotted for (ra = 1000, =1, and dr = 0.15 & 0.45, with =0◦, = 30◦, and  = 45◦, respectively. the above figures show two non–symmetric convective cells. the distribution of local nusselt number on cold and hot walls is shown in fig. (13) with different values of inclination angle ( ) at ra = 1000, dr = 0.15, f = 3, and = 0.6. for  < 45o, as  increases the value of local nusselt number along the cold and hot walls increases and has a peak value at (= 39o – 41o). while the local nusselt number decreases from its peak value as  increases more for the given values of other parameters. fig.(19) shows the variation of average nusselt number for the hot wall as a function of ( and ra). at = 0, it can be seen that the nusselt number attains the maximum value at = 39.2o because the effective height of the hot wall take the maximum value at this orientation which represents maximum heat transfer rate for named conditions; but at = 45o, the effective height of the hot wall decreases due to the gravitational buoyancy force. however, there is little difference among the magnitude of the average nusselt number at different inclination angle for = 0. when there exists temperature variation on hot wall (  > 0), the heat transfer is enhanced with the increase of  and the average nusselt number takes maximum value at about  = 1 and dr = 0.15 for = 40.1o. 6. conclusions a numerical study was performed to examine free convection heat transfer and fluid flow in an inclined annulus between two concentric square cavities filled with a porous medium. important conclusions were obtained from the study as follows : 1heat transfer is increased with the increase of rayleigh number. 2the local nusselt number on hot wall (heated wall) is changed with a sinusoidal function according to its temperature variation. 3average nusselt number is changed by a sinusoidal function as a wave number (f) increases and has a maximum value (maximum heat transfer) at (f = 0.75) for high values of rayleigh number (ra = 500 and 1000) and at (f = 0.7) for (ra = 10 to 200). 4as the amplitude (  ) increases, value of nusselt number is increased making wavy variation in streamlines. 5numerical results reveal that an increase at the dimension ratio (dr) will result in a decrease at the average nusselt number at the hot wall. 6the rate of heat transfer is enhanced with the increase angle of inclination ( ) of the inclined annulus from horizontal plane and the peak in average nusselt number occurs between (39o   41o), depending upon previous parameters. while the average nusselt number decreases from its peak value as  increases from horizontal above these values. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ nabeel mohammed jasim al-khwarizmi engineering journal, vol. 6, no. 3, pp 45 60 (2010) ٥٢ fig. 3. streamlines of flow at ra= 10, f =1, & φ=0 for a)  = 0, b)  = 0.2, c)  = 0.6, d)  = 1 and 1) dr= 0.15, 2) dr= 0.3, 3) dr= 0.45 . fig.4. isothermal contours at ra= 10, f =1, & φ=0 for a)  = 0, b)  = 0.2, c)  = 0.6, d)  = 1 and 1) dr= 0.15, 2) dr= 0.3 3) dr= 0.45 . (a1) (b1) (c1) (d1) (a2) (b2) (c2) (d2) (a3) (b3) (c3) (d3) (a1) (b1) (c1) (d1) (a2) (b2) (c2) (d2) (a3) (b3) (c3) (d3) this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ nabeel mohammed jasim al-khwarizmi engineering journal, vol. 6, no. 3, pp 45 60 (2010) ٥٣ fig. 5. streamlines of flow at ra= 1000, f =1 & φ=0, for a)  = 0, b)  = 0.2, c)  = 0.6, d)  = 1 and 1) dr= 0.15, 2) dr= 0.3, 3) dr= 0.45 . fig. 6. isothermal contours at ra= 1000, f =1 & φ=0 for a)  = 0, b)  = 0.2, c)  = 0.6, d)  = 1 and 1) dr= 0.15, 2) dr= 0.3, 3) dr= 0.45 . (a1) (b1) (c1) (d1) (a2) (b2) (c2) (d2) (a3) (b3) (c3) (d3) (a1) (b1) (c1) (d1) (a2) (b2) (c2) (d2) (a3) (b3) (c3) (d3) this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ nabeel mohammed jasim al-khwarizmi engineering journal, vol. 6, no. 3, pp 45 60 (2010) ٥٤ fig. 7. streamlines of flow at ra= 1000,  =1 & dr= 0.15 for a) φ = 0o , b) φ = 30o, c) φ = 45o , and 1) f = 3, 2) f = 5. fig. 8. isothermal contours at ra= 1000,  =1 & dr= 0.15 for a) φ = 0o , b) φ = 30o , c) φ = 45o and 1) f = 3, 2) f = 5. (a1) (b1) (c1) (a2) (b2) (c2) (a1) (b1) (c1) (a2) (b2) (c2) this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ nabeel mohammed jasim al-khwarizmi engineering journal, vol. 6, no. 3, pp 45 60 (2010) ٥٥ fig. 9. streamlines of flow at ra= 1000,  =1 & dr= 0.45 for a) φ = 0o , b) φ = 30o , c) φ = 45o and 1) f = 3, 2) f = 5. fig. ١٠. isothermal contours at ra= 1000,  =1 & dr= 0.45 for a) φ = 0o , b) φ = 30o , c) φ = 45o and 1) f = 3, 2) f = 5. (a1) (b1) (c1) (a2) (b2) (c2) (a1) (b1) (c1) (a2) (b2) (c2) this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ nabeel mohammed jasim al-khwarizmi engineering journal, vol. 6, no. 3, pp 45 60 (2010) ٥٦ fig.١١. distribution of local nusselt number at ra= 1000, dr=0.3,  =0.6, & φ=0 fig.١٢. distribution of local nusselt number at ra= 1000, f = 1,  =0.6, & φ=0 fig.١3. distribution of local nusselt number at ra= 1000, dr=0.15,  =0.6, & f =3 fig.١٤. distribution of local nusselt number at ra= 1000, dr=0.3, f =1, & φ=0 fig.١٥. distribution of local nusselt number at dr=0.3, φ=0,  =0.6, & f =1 fig.١٦. distribution of local nusselt number at dr=0.3, φ=0,  =0.6, & f =3 hot wall cold wall nu y-0.5 0 0.5 1 1.5 2 0 0.2 0.4 0.6 0.8 1 f = 0 f = 1 f = 3 f = 5 -0.5 0 0.5 1 1.5 2 0 0.2 0.4 0.6 0.8 1 dr= 0 dr= 0.15 dr= 0.3 dr= 0.45 nu y hot wall cold wall -0.4 0.1 0.6 1.1 1.6 0 0.2 0.4 0.6 0.8 1 φ = 0 φ = 30 φ = 45 nu y hot wall cold wall -1 -0.5 0 0.5 1 1.5 2 2.5 0 0.2 0.4 0.6 0.8 1 є= 0 є= 0.2 є= 0.6 є= 1 nu y hot wall cold wall -0.2 0 0.2 0.4 0.6 0 0.2 0.4 0.6 0.8 1 ra= 10 ra= 100 ra= 200 nu y hot wall cold wall -0.2 0 0.2 0.4 0.6 0 0.2 0.4 0.6 0.8 1 ra= 10 ra= 100 ra= 200 nu y hot wall cold wall this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ nabeel mohammed jasim al-khwarizmi engineering journal, vol. 6, no. 3, pp 45 60 (2010) ٥٧ fig.١7. variation of average nusselt number on the hot wall for different values of rayleigh number (ra), dimension ratio (dr), and amplitude (  ) at φ=0 & f =3. fig.١٨. variation of average nusselt number on the hot wall for different values of dimension ratio (dr), amplitude (  ), and wave number (f) at ra = 10 & 1000, and φ=30o. a) dr= 0.15 ra=1000 ra=10 0.1 1 10 100 0 1 2 3 4 5 є= 0 є= 0.2 є= 0.6 є= 1 nua f b) dr= 0.3 0.1 1 10 100 0 1 2 3 4 5 є= 0 є= 0.2 є= 0.6 є= 1 nua f ra=1000 ra=10 0.1 1 10 100 0 1 2 3 4 5 є= 0 є= 0.2 є= 0.6 є= 1 nua f ra=1000 ra=10 c) dr= 0 2 4 6 8 10 12 0 200 400 600 800 1000 dr= 0.15 dr= 0.3 dr= 0.45 a)  = 0 nua ra 0 2 4 6 8 10 12 14 16 18 0 200 400 600 800 1000 dr= 0.15 dr= 0.3 dr= 0.45 b)  = 0.2 nua ra 0 5 10 15 20 25 30 0 200 400 600 800 1000 dr= 0.15 dr= 0.3 dr= 0.45 c)  = 0.6 nua ra 0 5 10 15 20 25 30 35 40 45 0 200 400 600 800 1000 dr= 0.15 dr= 0.3 dr= 0.45 d)  = 1 nua ra this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ nabeel mohammed jasim al-khwarizmi engineering journal, vol. 6, no. 3, pp 45 60 (2010) ٥٨ fig.١٩. variation of average nusselt number on the hot wall for different values of rayleigh number (ra), amplitude (  ), and dimension ratio (dr) at f =5. nomenclature dimension ratio, (l1/l).dr gravitational acceleration, (m/s2).g permeability of the porous medium, (m2).k wave number of heated side wall temperature (wave frequency). f width or height of the outer wall, (m).l width or height of the inner wall, (m).l1 total number of grid points.n local nusselt number.nu average nusselt number.nua rayleigh number for porous medium.ra temperature, (k).t velocity components, (m/s).u,v cartesian coordinates, (m).x,y non-dimensional coordinates.x,y greek symbols α thermal diffusivity, (m2/s).  thermal expansion coefficient, (1/k). ε non-dimensional amplitude. φ inclination angle, (degree). θ non-dimensional temperature. μ dynamic viscosity, (kg/m.s). ρ density, (kg/m3). ψ stream function, (m2/s). ψ non-dimensional stream function. a) dr= 0.15 0 5 10 15 20 25 30 35 40 45 0 200 400 600 800 1000 φ = 0 φ = 30 φ = 45 ١ ٠ nua ra c) dr= 0.45 0 5 10 15 20 25 30 35 40 0 200 400 600 800 1000 φ = 0 φ = 30 φ = 45 ١ ٠ nua ra 0 5 10 15 20 25 30 35 40 0 200 400 600 800 1000 φ = 0 φ = 30 φ = 45 ١ ٠ nua ra b) dr= 0.3 this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ nabeel mohammed jasim al-khwarizmi engineering journal, vol. 6, no. 3, pp 45 60 (2010) ٥٩ subscript c cold. h hot. 7. references [1] nield, d. and bejan, a., "convection in porous media", 2nd edition, springer, new york, ny, (1999). [2] p. cheng, "heat transfer in geothermal systems", adv. heat transfer 4 (1978), 1–105. [3] p.h. oosthuizen, and h. patrick, "natural convection in an inclined square enclosure partly filled with a porous medium and with a partially heated wall", htd 302, american society of mechanical engineers, heat transfer division, (publication), (1995), 29–42. [4] p. nithiarasu, k.n. seetharamu, and t. sundararajan, "numerical investigation of buoyancy driven flow in a fluid saturated non-darcian porous medium", int. j. heat mass transfer 42 (7) (1998), 1205–1215. [5] a.m., al-amiri, "analysis of momentum and energy transfer in a lid driven cavity filled with a porous medium", int. j. heat mass transfer 43 (2000), 3513–3527. [6] nawaf h. saeid, "natural convection in a square porous cavity with an oscillating wall temperature", the arabian journal for science and engineering, vol. 31, no. 1b (2005), 35 – 46. [7] j.p. caltagirone, and s. bories, "solutions and stability criteria of natural convective flow in an inclined porous layer", j. fluid mech. 155 (6) (1985), 267–287. [8] p. vasseur, m.g. satish, and l. robillard, "natural convection in a thin inclined porous layer exposed to a constant heat flux", int. j. heat mass transfer 30 (3) (1987), 537–549. [9] m. sen, p. vasseur, and l. robillard, "multiple steady states for unicellular natural convection in an inclined porous layer", int. j. heat mass transfer 30 (10) (1987), 2097–2113. [10] a.c. baytas, "entropy generation for natural convection in an inclined porous cavity", int. j. heat mass transfer 43 (12) (2000), 2089–2099. [11] saeid, n. h. and mohamed, a., "periodic free convection from a vertical plate in a saturated porous medium, nonequilibrium model", international journal of heat and mass transfer, vol.48. (2006), 3855 3863. [12] yoo, j.s., "thermal convection in a vertical porous slot with spatially periodic boundary temperature", international journal of heat and mass transfer, vol. 46, issue 2, (2003), 381-384. [13] robert w., "numerical marching techniques for fluid flow with heat transfer", lewis research center cleveland, ohio and carnegie – mellon university pittsburgh, pennsylvania. [14] najdat n. a., ''laminar flow separation in constructed channel'', ph.d. thesis, michigan state university, 1987. [15] john d. anderson, "computational fluid dynamics', international editions 1995 by mcgraw – hill. [16] chan, b. k., ivey, c. m., and barry, j. m., "natural convection in enclosed porous medium with rectangular boundaries", journal of heat transfer, vol.2, (1970), 2127. [17] burns, p. j., chow, l. c., and tien, c. l., "convection in vertical slot filled with porous insulation", int. journal of heat mass transfer, vol.20, (1974), 919-926. [18] bejan, a., and tien, c., "natural convection in a horizontal porous medium subjected to an end-to-end temperature difference'', journal of heat transfer, vol.100, (1978), 191-198. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ م د جاس ل محم د نبی یة المجل وارزمي الھندس ة الخ دد ٦مجل فحة3، الع 60-45 ، ص )٢٠١٠( ٦٠ المراكز ممتلئ نانتقال الحرارة بالحمل الحر في تجویف مائل بین فجوتین مربعتین متحدتی بوسط مسامي و مسخن بدرجة حرارة غیر منتظمة نبیل محمد جاسم جامعة الكوفة /كلیة الھندسة/ قسم الھندسة المیكانیكیة nabeelalzurfi@yahoo.com: البرید االلكتروني ةالخالصـ امي ننعرض في ھذا البحث دراسة عددیة لتدفق الحمل الحر المستقر في بعدین داخل تجویف مائل بین فجوتین مربعتین متحدتی ط مس المراكز ممتلئ بوس ا . األخرى معزولة حیث تكون الجدران الخارجیة الجانبیة مسخنة بدرجة حرارة مختلفة بینما تكون جمیع الجدران ر وفق رارة تتغی ة ح ھ درج خن ل دار المس الج ائع . لدالة جیبیھ حول قیمة متوسط درجة الحرارة رض إن الم د افت امي وق ط المس تم االعتماد على مودیل دارسي في التمثیل الریاضي النتقال الحرارة في الوس ا الحل العددي للمعادالت أنجز بواسطة حل. ھو مائع بوسین المعیاري ر وق ة الف تخدام طریق ة باس ان و الطاق ة الجری ن دال ل م ادالت ك ق تمع ددة و تطبی المح دد . مع استخدام طریقة تحت التراخي) سیدل –كاوس (طریقة ة لع یم مختلف ى ق تم تمثیل النتائج العددیة بداللة خطوط االنسیاب و درجات الحرارة باالعتماد عل ى ٠من ( كما تم دراسة تأثیر كل من سعة الموجة). o٤٥ إلى o٠من (و زاویة المیل , )0.45 إلى 0.15من ( نسبة البعد, ) ١٠٠٠ إلى ١٠من (رایلي ) ١ إل ابقة تالنتائج بینت تأثیر المعامال. لدرجة الحرارة المتغیرة للجدار الجانبي الخارجي المسخن على انتقال الحرارة) ٥ إلى ٠من (و عدد الموجات (and f ,الس  ,φ(ra, dr, ل , كما بینت النتائج إن عدد نسلت ھو دالة قویة من عدد رایلي . على خطوط الجریان و درجة الحرارة ة المی د , زاوی بة البع ي , نس ر ف و التغی عة )40.1o(ویة المیل و زا, )0.15( إلىوتتمركز القیمة القصوى لمعدل عدد نسلت عندما تكون قیمة نسبة البعد مساویة . درجة الحرارة ون س دما تك و عن .)١٠٠٠(لقیمة عدد رایلي ) ٠.٧٥و ١( إلىو عدد الموجات مساویة this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ <4d6963726f736f667420576f7264202d2033332d3434d1ede320e6d1c4ec20e6d4ede3c7c1> al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 15, no. 4, december, (2019) p. p. 3345 wear behavior performance of polymeric matrix composites using taguchi experiments reem alaa mohammed* ruaa haitham abdul raheem** shaymaa hasan khazaal*** *,** department of materials engineering/ university of technology / iraq *** department of applied science/ university of technology/ iraq *email: 10904@uotechnology.edu.iq ** email: lolo_ru1982@yahoo.com *** email: shaymaa8104@yahoo.com (received 25 april 2019; accepted 31 june 2019) https://doi.org/10.22153/kej.2019.07.006 abstract this research estimates the effect of independent factors like filler (3%, 6%, 9%, 11% weight fraction), normal load (5n, 10n, 15n), and time sliding (5,7 , 9 minutes) on wear behavior of unsaturated polyester resin reinforced with jute fiber and waste eggshell and, rice husk powder composites by utilizing a statistical approach. the specimens polymeric composite prepared from resin unsaturated polyester filled with (4% weight fraction) jute fiber, and (3%, 6%, 9%, 11% weight fraction) eggshell, and rice husk by utilizing (hand lay-up) molding. dry sliding wear experiments were carried utilizing a standard (pin on disc test setup) following a well designed empirical schedule that depends on taguchi’s experimental design l9 (minitab 16) with the determined (s/n) ratio and analysis of different (anova) optimal factors to minimize the wear rate. results exhibit that the presence the of 11% weight fraction eggshell and rice husk powder with 4% weight fraction jute fiber improves the wear resistance of unsaturated polyester composite materials significantly. the filler content was observed to be the major significant factor influencing the wear rate followed by time sliding and normal load. from the results of the s/n ratio, the optimization of wear parameters is obtained at specimens a3, a6, a7, and a10 as to minimize wear rate. keywords: unsaturated polyester resin, eggshell, rice husk, jute fiber, wear behavior, taguchi’s method, anova. 1. introduction recently there has been a rapid development in utilizing natural fibers like: jute, sisal, coconut...etc. with thermoset resin matrix materials in various industrial applications due to the fact these fibers are available in natural, nontoxic, low density, lightweight and has an ability combination between high performance and low cost [1 and 2]. there are various polymers that can be used as a matrix for composite materials like (thermoset and thermoplastics), the most frequently used thermoset polymers are epoxy resin, unsaturated polyester resins, and vinylester. a thermoset is a hard and interrelated material that loses mechanical and chemical properties and is non-modifiable when exposed to heat [3]. unsaturated polyester resin is a type of thermosetting polymer that is formed by reacting with an unsaturated monomer or pre-polymer by having a carbon-to-carbon bond in its polymer chain and has a good mechanical and physical property so it is suitable for applications requiring high resistance, corrosion resistance, moisture resistance, thermal insulation and good electrical properties [4 & 5]. the wear behavior is divided into four types, which are erosive wear; abrasive wear; adhesive wear; and surface fatigue wear in this research study the adhesive reem alaa mohammed al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 3344 (2019) 34 wear and erosion wear [6]. adhesive wear behavior can be defined as the process that occurs as a result of interaction among the surface of the solid material with the environmental conditions such as temperature, speed, impact loads and also various kinds of with be better such as solid or liquid or gas [7]. this kind of wear occurs in the case of sliding surfaces to each other under the influence of the load so that pressure high enough to cause local plastic deformation and adhesion [8]. there are many studies that have investigated the wear and erosive behavior and attempted to find the factors that have the most effect on the values of wear and erosive resistances. s.majhi, et.al. [9] illustrated the wear behavior of composite polymer made from epoxy resin reinforced with (5%, 10%, 15%, 20% w.f) rice husk. the results show the specimen (epoxy + 10% r.h) give better resistance to wear behavior than other weight fractions. s. srinivasa and k. manonmani [10] examine the wear behavior of hybrid composites constituents from (2%, 5%, and 9%wt.) titanium oxide filled with (30%, 4%, and 50% wt.) fiber at varying glass fiber lengths of 1, 2, and 3 cm into unsaturated polyester resin. taguchi’s test design procedure was applied to select a parametric analysis of the variable fiber content, fiber length and filler material content. events prove the fiber content parameter was a major effect on wear rate and also with the increase in fiber content comes the increase in resistance wear rate. a.h. majeed et.al. [11] studied the influence of varying ratios as 0%, 0.5%, 1%, 1.5 %, 2%, 2.5%, and 3% silica fume, glass powder, and carbon black filled with unsaturated polyester resin on impact test, hardness test, bending test, compressive strength and wear test. results reveal the impact and hardness, improve with added sf, gp, cb, while the bending test improves with add gp associated with sf and cb. compressive strength improves with sf compared with gp and cb, but the wear rate resistance improves with added gp and sf more than cb. younis et.al. [12] studied the effect of 1%, 3%, and 5% wt. nano silica particles filled with 4% wt. glass fiber (chopped/woven) in a polyester resin matrix on the wear behavior, tensile strength, impact strength and hardness shore d. load (3 n, 5n and 7n), sliding speed (2 m/s), sliding distance (7cm) and sliding time (15 minutes) are the factors influencing on the wear behavior rate were investigated. from these results it can be seen the presence 4% woven glass fiber with 5% nano-silica in an epoxy resin matrix specimen improves wear behavior, tensile strength, impact strength and hardness shore d for polymer composite highly than specimens filled 4% chopped glass fiber with 5% nano silica particles. the purpose of this research is to study the influence weight fraction of jute fiber, waste (eggshell and rice husk powder) reinforced with unsaturated polyester on dry sliding wear. taguchi’s experimental design (l9) was used and the anova analysis in order to investigate the effect of factors (filler content, load applied, sliding time) on the dry sliding wear resistance. the resistance unsaturated polyester resins was improved by adding jute fiber with small amounts from waste eggshell and rich husk powder under the conditions for dry sliding wear behavior. 2. materials raw 2.1 unsaturated polyester resin the unsaturated polyester resin (perpol 111), which was used as matrix in this work has good tensile properties, flexural properties, good corrosion resistance and performs satisfactorily in water and sea-water. table 1 shows the physical and mechanical properties of polyester resin used in this work and equipped by the united arab emirates company. table 1, shows the physical and mechanical properties of polyester resin. properties values tensile strength 55-65 mpa tensile modulus 3600-2800 mpa flexural strength 182-192 mpa flexural modulus 6500-6900 mpa elongation at break 1.9-2.3 % heat deflection temperature 63-71 c° water absorption after 24 hrs at 23 c° 15-19 mg density 1.10-1.11 gm/cm3 2.2 jute fiber the mechanical properties of the jute fiber used in this work as reinforced materials are shown in table 2 [13]. reem alaa mohammed al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 3344 (2019) 35 table 2, shows the mechanical properties of jute fiber [13]. 2.2 waste eggshell in this research, eggshell waste will be used as a reinforcement material with unsaturated polyester resin. eggshells were washed with water to remove membranes from the eggshell and dried at room temperature, later milling for 3 hours until the fine powder was obtained. table 3 shows the chemical composition of eggshells after milling (examined by the xrf technique). the average particle size of eggshell powder is shown in figure 1, where the average particle size of eggshell waste was (17µm). table 3, chemical composition of eggshell using x-ray fluorescence spectrometer component ratio% component ratio% cao 50.25 cl 0.029 sio2 0.020 k2o 0.080 al2o3 0.022 mno 0.030 mgo 0.055 tio2 0.0043 fe2o3 0.044 cuo 0.0088 na2o 0.55 v2o5 0.0014 p2o3 0.045 cr2o3 0.0028 sro 0.033 zno 0.0027 nio 0.0020 i 0.0020 so3 0.64 bao 0.0038 fig. 1. particle size analyzer of eggshell powder after milling. 2.3 waste rice husk the rice husk is the agricultural waste used in this research as a reinforcement material with unsaturated polyester resin. rice husk consists of 20% silica, 30-40% cellulose, 25-30% lignin and 10-15% ash, and 5-10% humidity [14]. the rice husk was initially washed with water to remove dust and suspended materials, dried at room temperature and then grinded for 3 hours until the fine powder was obtained. table 4 shows the chemical composition of the rice husk after milling examination by using (xrf) technique. the average particle size of rice husk is shown in figure 2, where the average particle size of egg shells is (45µm). table 4, chemical composition of rice husk by using an xray fluorescence spectrometer) component ratio% component ratio% cao 0.44 cl 0.071 sio2 25.33 k2o 0.47 al2o3 0.075 mno 0.022 mgo 0.038 tio2 0.0010 fe2o3 0.98 cuo 0.075 na2o 0.25 v2o5 0.00060 p2o5 0.033 cr2o3 0.0037 sro 0.0035 zno 0.0093 nio 0.0083 i 0.0023 so3 0.045 bao 0.0036 fig. 2. particle size analyzer of rice husk powder after milling 3. experimental work 3.1 preparing of test specimens the preparation of samples of polymer composite matrix materials was done by hand lay up method. initially, the preparing mold from the properties values tensile strength 400-800 mpa young modulus 10-30 gpa elongation at break 1.8% density 1.46 gm/cm3 reem alaa mohammed al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 3344 (2019) 36 glass with a dimension of (20 × 20 × 0.5 cm), as shown in figure 3 and must be covered together with a layer of nylon until adherence between specimens and mold is prevented. then the jute fibers are cut according to mold dimensions and calculate the weight fraction of the jute fiber and filler (eggshell and rice husk) depending on the role of mixture [15]. next, the unsaturated polyester resins is mixed with a filler (3%, 6%, 9% and 11% weight fraction eggshell and rice husk) by using a glass rod until homogenous mixing is obtained and then adds the hardener to the mixture and the mixing process continues for 15 minutes. part of the mixture was poured into the mold and layer jute fiber (4% weight fraction) was put and the remaining amount of mixture was poured and left for 24 hours at room temperature. samples will be set in the oven at 55 degrees celsius for 1 hour in order to remove the remaining stresses and get better bonding [16&, 17]. the specimens were sliced according to astm (wear g99-04) tests. table 5 shows the detailed composition of the specimens. fig. 3. sample preparation mold. table 5, detail composition of the specimens 3.2 wear test a dry sliding wear test is carried according to pin-on-disc. the wear device consists of a flat metal arm containing holder that was installed in the specimen and a rotating iron disc connected to an electric motor. the hardness of the iron disc is 269 hb and the velocity is 950 rpm as shown in figure 4, is located in the materials engineering / department, technology university. the specimen dimensions in this test were (10 mm width, 25mm length, and 5mm thickness) according to astm (g99-04) [18] as shown in figure 5. the wear behavior rate can be calculated from equations 1and 2 [19]. w. r � ∆� �.� …(1) where: w.r: wear rate (gm/mm) ∆w: the difference weight (gm) s.d: distance of sliding can be calculated from equation 2 s. d � s ∗ t …(2) where: s: speed of sliding (mm/min) t: time (min) fig. 4. device used in wear test. fig. 5. models for specimens wear test. 3.3 taguchi experimental design the taguchi design has traditionally been specimens composition a1 up a2 up+4% j.f a3 up+4% j.f +3% e.s a4 up+4% j.f +6% e.s a5 up+4% j.f +9% e.s a6 up+4% j.f +11% e.s a7 up+4% j.f +3% r.h a8 up+4% j.f +6% r.h a9 up+4% j.f +9% r.h a10 up+4% j.f +11% r.h reem alaa mohammed al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 3344 (2019) 37 adopted to improve design standards because this systematic approach can greatly reduce overall experimental costs and test time. using the taguchi l9 orthogonal array design, the optimal experimental state can be easily determined based on the s/n analysis required to estimate experimental results. in general, there are three types of signal-to-noise analysis applicable: 1, lower is better, 2 nominal is better, and 3 higher is better. in this current work, the main objective is to reduce the wear, so it was used the lower is better, according to equation 3 [20]. table 6 shows the levels of the factors used in the experiments of the wear test. � � � −10 log � � �∑�2� …(3) where; n = number of observations. y = erosive wear rate. table 6, levels of variables utilized in the experiment of wear behavior 4. results and discussion 4.1 wear test the results wear rate for all experiments was carried out according to the predetermined design on specimens composites are presented in tables (7-10), also these tables present the experimental wear rate along with the signal-to-noise ratio for each single test run. clearly from the tables (710) the wear rate values decrease with add weight fraction from waste (eggshell and rice husk powder reinforced with jute fiber into unsaturated polyester), where the lowest wear rate was found in the specimen (up+4%jute fiber+11% eggshell and rice husk) (0.2×10-4 gm/mm, 1.2×104gm/mm) respectively compared with the other specimens, due to the content of the fiber and filler acts as an obstacle to shear deformation during the sliding conditions, also the wear behavior can be based on both abrasion and adhesion, this agrees with [12&21]. figure 6 shows the main effects plot for (s/n) ratios on wear rate, clear from the main effects of the s/n measurements that the incorporation factor of a3, a6, a7, a10, b1, and c3 gives a lower wear rate. it is clear through the taguchi experimental that the lowest wear rate can be obtained when the filler content (a) with the sliding time (c) is at the highest level, while the load (b) is at the lower level. these results indicated in the change in sliding conditions has a direct effect on the wear rate of the composite polymer specimens. figure 7 shows the relationship between the filler content and wear behavior rate, where the specimens reinforced with eggshell powder give wear resistance better than specimens reinforced with a rice husk powder, due to the natural chemical composition of eggshells compared to chemical composition of the rice husk where the presence of calcium oxide is (50.25%) in eggshell powder gives a better correlation with the resin matrix material, also the eggshells powder increases surface hardness of the polymeric composite thus improving the natural bond between the matrix material and filler materials. figure 8 shows the effect of the load applied on the wear behavior rate, this figure shows a decrease in wear resistance with increasing applied load from (5 n to 15 n), from the taguchi experiment on the specimens reinforced with 11w.f% (eggshell and rice husk powder) give better wear resistance at 5 a load. due to that increasing the applied load increases friction on the surface of composite polymeric thus causes a higher weight loss, this agrees with [22]. also the nature of interdependence between the resin matrix and the reinforcing material depends on several factors, including the particle size and the chemical composition of the reinforcing materials[23], where the particle size of waste eggshell was (17µm), which is smaller than waste rice husk (45µm), therefore the specimens reinforced with eggshell powder and jute fiber in unsaturated polyester resin give resistance wear rate better than reinforced with a rice husk powder. figure 9 displays the effect of time sliding on the wear behavior rate. the taguchi, experiments show that the increased time sliding from (5 to 9 min) leads to thermal softening and weakness in the typical polymer composite material, thus increasing the wear rate these results agree with [24] variable level ii ii2 iii4 unit weight fraction a1 a2 a3 w.f % a4 a5 a6 a1 a2 a7 a8 a9 a10 normal load applied 5 10 15 n sliding time 5 7 9 min reem alaa mohammed al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 3344 (2019) 38 table 7, results of wear rate with the output results using l9 orthogonal array of specimens (pure polyester, 4% jute fiber, 3% eggshell powder) table 8, results of wear rate with the output results using l9 orthogonal array for specimens (6%, 9%, 11% eggshell powder) exp. filler (a) load (n) (b) time (c) wear rate gm/mm s/n 1 a4 5 5 3.6×10-4 -11.1261 2 a4 10 7 3.4×10-4 -10.6296 3 a4 15 9 3.1×10-4 -9.8272 4 a5 5 7 1.1×10-4 -13.9794 5 a5 10 9 1.5×10-4 -3.5218 6 a5 15 5 1.8×10-4 -5.1055 7 a6 5 9 0.2×10-4 -0.8279 8 a6 10 5 0.5×10-4 -6.0206 9 a6 15 7 0.4×10-4 -7.9588 table 9, results of wear rate with the output results using l9 orthogonal array of specimens (pure polyester, 4%jute fiber, 3% rha) exp. filler (a) load (n) (b) time (c) wear rate gm/mm s/n 1 a1 5 5 9.8×10-4 -19.8245 2 a1 10 7 8.5×10-4 -18.5884 3 a1 15 9 7.7×10-4 -17.7298 4 a2 5 7 7.6*10-4 -17.6163 5 a2 10 9 7.2×10-4 -17.1466 6 a2 15 5 8.7×10-4 -18.7904 7 a7 5 9 5.0×10-4 -13.9794 8 a7 10 5 6.6×10-4 -16.3909 9 a7 15 7 6.5×10-4 -16.2583 table 10, results of wear rate with the output results using l9 orthogonal array of specimens (6%, 9%, 11% rha) exp. filler (a) load (n) (b) time (c) wear rate gm/mm s/n 1 a8 5 5 4.4×10-4 -12.8691 2 a8 10 7 4.1×10-4 -12.2557 3 a8 15 9 3.8×10-4 -11.5957 4 a9 5 7 2.1×10-4 -6.4444 5 a9 10 9 2.5×10-4 -7.9588 6 a9 15 5 2.7×10-4 -8.6273 7 a10 5 9 1.2×10-4 -1.5836 8 a10 10 5 1.5×10-4 -3.5218 9 a10 15 7 1.4×10-4 -2.9226 exp. filler (a) load (n) (b) time (c) wear rate gm/mm s/n 1 a1 5 5 9.8 ×10-4 -19.8245 2 a1 10 7 8.5×10-4 -18.5884 3 a1 15 9 7.7×10-4 -17.7298 4 a2 5 7 7.6×10-4 -17.6163 5 a2 10 9 7.2×10-4 -17.1466 6 a2 15 5 8.7×10-4 -18.8897 7 a3 5 9 4.1×10-4 -12.2557 8 a3 10 5 5.7×10-4 -15.1175 9 a3 15 7 5.2×10-4 -14.3201 reem alaa mohammed al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 3344 (2019) 39 fig. 6. (a, b, c, d) represent the main effects plot for s/n ratios on the wear behavior rate for all specimens. reem alaa mohammed al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 3344 (2019) 40 fig. 7. represent the effect filler content on the wear rate for all specimens (eggshell and rice husk). fig. 8. represents effect load applied on the wear rate for all specimens (eggshell and rice husk). reem alaa mohammed al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 3344 (2019) 41 fig. 9. represents effect time sliding on the wear rate for all specimens (eggshell and rice husk). 4.2 analysis anova for wear rate results the anova analysis is used to understand the effect of the factors and their interaction on the wear rate and allows determining the effect of each variable on the total difference of the results. tables (11,12) offer anova analysis results for specimens reinforced by eggshell powder, while tables (13-14) offer anova analysis results for specimens reinforced by rice husk powder. in the tables, the last column represents the contribution percentage p for each variable and determines the percentage of the effective factors on the wear rate. when p-value is less than 0.05, this factor has a significant influence on the wear behavior rate. table 11 shows the p value of the filler (a) and time sliding (c) (0.012, 0.054) respectively, have a greater effect on the wear behavior rate, whereas the p value of the applied load (b) (0.875) have less influence on the wear behavior rate. table 12 shows the p value of the filler (a) and load applied (b) (0.009, 0.053) respectively, which has more significance on the wear behavior rate, while the p value of the time sliding (c) (0.339) has less influence on the wear behavior rate. table 13 shows the p value of the filler (a) (0.04) has more effect on wear rate, while p values (0.975, 0.097) of the load applied (b) and time sliding (c) respectively have less influence on the wear behavior rate. table 14 shows the p value of the filler (a) and load applied (0.012, 0.054) respectively, have most significance on the wear behavior rate, while the p value of the time sliding (c) (p= 0.362) less influence on the wear behavior rate. from these results can be noted in the specimens (a1, a2, a3, a7) was the filler (a) and time sliding (c) more influence on the wear behavior rate while load applied (b) less influence on the wear behavior rate, but in the specimens (a4, a5, a6, a8, a9, a10) the filler (a) and time sliding (c) have more effect on the wear behavior rate while the load applied (b) has less effect on wear rate. reem alaa mohammed al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 3344 (2019) 42 table 11, anova analysis of specimens (pure polyester, 4% jute fiber, 3% eggshell powder) sourcee dff seq sss adj sss adj ms. ff p. filler (a) 2 22.1667 22.1667 11.0833 85.26 0.012 load (b) 2 0.0067 0.0067 0.0033 0.03 0. 875 time sliding (c) 2 4.526 4.526 2.2633 17.41 0.054 error 2 0.2600 0.2600 0.1300 total 8 26.9600 table 12, anova analysis of specimens (6%, 9%, 11% eggshell powder) sourcee dff seq sss adj sss adj ms. ff p. filler (a) 2 13.8200 13.8200 6.9100 109.11 0.009 load (b) 2 0.0467 0.0467 0.0233 0.37 0.053 time sliding (c) 2 0.2467 0.2467 0.1233 1.95 0.339 error 2 0.1267 0.1267 0.0633 total 8 14.2400 table 13, anova analyses of specimens (pure polyester, 4% jute fiber, 3% rice husk) sourcee dff seq sss adj sss adj ms. ff p. filler (a) 2 10.8689 10.8689 5.4344 22.54 0.04 load (b) 2 0.0689 0.0689 0.0344 0.14 0.975 time sliding (c) 2 4.5089 4.5089 2.2544 9.35 0.097 error 2 0.4822 0.4822 0.2411 total 8 15.9289 table 14, anova analysis of specimens (6%, 9%, 11% rice husk powder) 5. conclusions below are the most important conclusion researches. 1. the presence of wastes eggshell and rice husk powder into unsaturated polyester resin with 4% weight fraction jute fiber can significantly reduce the wear loss. the optimal wear rate characteristic was obtained at 11% weight fraction. 2. the specimens (up +4% j.f +11% e.s) and (up +4% j.f +11% r.h) give wear rate resistance (0.2×10-4 gm/mm) and (1.2×10-4 gm/mm) respectively at load applied (5 n) and time sliding (9 min), while the specimen (up) give higher wear rate (9.8×10-4 gm/mm) at load applied (15n) and time sliding (9 min). 3. filler content was observed to be the major significant factor influencing the wear rate followed by (c) (time sliding) and (d) (normal load). 4. from analysis of variance (anova) exhibit at the specimens (a1, a2, a3, a7) the filler and time sliding has most influence on the wear rate behavior and in the specimens (a4, a5, a6, a8, a9, a10) the filler, the load applied have most influence on the wear rate behavior. 5. the s/n ratio and, the optimization of wear parameters is obtained at specimens (a3, a6, a7, a10) as to minimize wear rate. 6. references [1] s. m sudhakar majhi, s. p. samantarai, s. k. acharya," tribological behavior of modified rice husk filled epoxy composite ", international journal of scientific & engineering research, vol. 3, issue 6, pp. 1-5 , 2012 . [2] r. haitham abdel-rahim, reem alaa mohammed. "experimental investigation of some properties of epoxy reinforced by egg shell particles ", international journal of mechanical engineering and technology, vol. sourcee dff seq sss adj sss adj ms. ff p. filler (a) 2 11.3867 11.3867 5.6933 81.33 0.012 load (b) 2 0.0267 0.0267 0.0133 0.19 0.054 time sliding (c) 2 0.2467 0.2467 0.1233 1.76 0.362 error 2 0.1400 0.1400 0.0700 total 8 11.8000 reem alaa mohammed al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 3344 (2019) 43 10, issue 1, pp.152-163, 2019. [3] r. alaa mohammed, "effect of al2o3 powder on some mechanical and physical properties for unsaturated polyester resin hybrid composites materials reinforced by carbon and glass fibers", engineering and technology journal, vol. 34, part (a), no. 12, pp. 23712379, 2016. [4] c. a harper, and e.m petrie., " plastics materials and processes: a concise encyclopedia", john wiley & sons, inc., 2003. [5] r. alaa mohammed, " study of some mechanical properties and erosive behavior by taguchi method for hybrid nano composites ", engineering and technology journal,vol. 36, part a, no. 4, 2018, doi: http://dx.doi.org/10.30684/etj.36.4a.15. [6] d. h. buckley,"surface effectin adhesion friction, wear and lubrication", elsevier, new york, 1981. [7] s. s. dara, s. chand,"text book of engineering chemistry", pp.234-259, (2007). [8] v. begriff, "systematic analysis of wear processes", pp.1-6, 1979. [9] s. majhi, s. p. samantarai, s. k. acharya, "tribological behavior of modified rice husk filled epoxy composite ", international journal of scientific & engineering research ", vol.3, issue 6, 2012. [10] s. srinivasa moorthy and k. manonmani, "research on sliding wear behavior of tio2 filled glass fiber reinforced polymer composite", research journal of applied sciences, engineering and technology, vol. 7, no.16, pp. 3356-3361, 2014. [11] a.h. majeed, s.q. ibrahim, " mechanical properties of unsaturated poltester filled with silica fumme, glass powder and carbon black", engineering and technology journal, vol. 35, part (a), no. 6, pp. 640-,647, 2017. [12] s. i. younis, j. k. oleiwi, reem alaa mohammed, " some mechanical properties of polymer matrix composites reinforced by nano silica particles and glass fiber ", engineering and technology journal, vol.36, no.12, part (a), pp.12831289, 2018. [13] p.k mallick, " fiber reinforced composites materials, manufacturing and design ", third edition, taylor and francis, 2008. [14] a. basim abdul hussein, e.saadi alhassani, reem alaa mohammed, " influence of coating with some natural based materials on the erosion wear behavior of glass fiber reinforced epoxy resin ", al-khwarizmi engineering journal, vol. 11, no. 2, pp. 20 30, 2015. [15] p.a. thornton and v.j. colangelo, "fundamentals of engineering materials", prentice-hall inc, 1985. [16] a. basim abdul hussein, e.s.al-hassani, reem alaa mohammed, " effect of natural materials powders on mechanical and physical properties of glass fiber / epoxy composite ", engineering and technology journal, vol.33, no.1, part (a), pp.175 197, 2015. [17] a. basim abdul hussein, e. s. al-hassani, reem alaa mohammed, " erosion wear behavior of industrial material reinforced epoxy resin composites and its coating with natural based material ", engineering and technology journal, vol.33, no.4, part (a), pp.902918, 2015. [18] annual book of astm standard," standard test method for wear testing with a pin-ondisk apparatus", g99-04, 2000. [19] [19] d. dowson, " the history of tribology ", longman, london, 1978. [20] reem alaa mohammed, rajaa kamil majeed, dalia mohammed gomaa, " study the erosion wear behavior for unsaturated polyester resin composites materials reinforced by carbon fibers with al2o3 powder using taguchi method ", journal of engineering and sustainable development, vol. 21, no. 5, pp.213-224, 2017. [21] m. sudheer, r. prabhu, k. raju," effect of filler content on the performance of epoxy /ptw composites ", advances in materials science and engineering, hindawi publishing corporation, vol.2014, pp.1-10, 2014, (doi.org/10.1155/2014/970468). [22] s. basavarajappa, k.v. arun, j. paulo davim," effect of filler materials on dry sliding wear behavior of polymer matrix composites – a taguchi approach ", journal of minerals & materials characterization & engineering, vol. 8, no.5, pp. 379-391, 2009. [23] s. chauhan, s. thakur, " effect of micro size cenosphere particles reinforcement on tribological characteristics of vinylester composites under dry sliding conditions ", journal of minerals and materials characterization and engineering, vol.11, pp. 938-946, 2012. [24] j. k. oleiwi,"a study of wear rate behavior of polyester reinforced by silica (sio2) particles", the iraqi journal for mechanical and material engineering, no.1, vol.10, pp.108-118, 2010. )2019( 3344، صفحة 4عددال، 15دجلة الخوارزمي الهندسية المجلمريم عالء محمد 44 لبوليمرية المركبة باستخدام تجارب تاكوجيأداء سلوك البلى لالنسجة ا ***شيماء حسن خزعل ** رؤى هيثم عبد الرحيم * ريم عالء محمد *،** قسم هندسة المواد / الجامعة التكنولوجية *** قسم العلوم التطبيقية / الجامعة التكنولوجية 10904@uotechnology.edu.iq : البريد االلكتروني * lolo_ru1982@yahoo.com : البريد االلكتروني ** shaymaa8104@yahoo.com : البريد االلكتروني *** الخالصة ،٥() ووقت االنزالق ١٥n، ١٠n ،٥nكسر وزني) ، الحمل العادي ( %١١ ،%٩ ،%٦ ،%٣( تأثير العوامل المستقلة مثل الحشوهذا البحث قيم ي ام نهج استخد ةطساونفايات مسحوق قشور البيض وقشور التمن بو القنبدقائق) على سلوك البلى لمتراكبات راتنج البوليستر غير المشبع المدعم بألياف ٩ ،٧ ٪ ، ٩٪ ، ٦٪ ، ٣و ( القنب% كسر وزني ألياف ٤يتم تحضير العينات البوليمرية المتراكبة من راتنجات البوليستر غير المشبعة المحشوه مع .إحصائي ً وزني اً ٪ كسر١١ عداد اختبار القرص) القياسي تجارب البلى االنزالقي باستخدام (دبوس على إ واجريت) قشور البيض وقشور التمن باستخدام القولبة اليدوية ا ) وتحليل s/n) مع حساب نسبة االشارة الى الضوضاء (١٦) ( مني تاب l9جيدا تعتمد على تصاميم تجارب تاكوجي ( ةمصمم ةباتباع جداول تجريبي ً وزني اً كسر% ١١التباين (االنوفا) االمثل للمتغيرات لتقليل معدل البلى. أظهرت النتائج أن وجود اً كسر% ٤من مسحوق قشور البيض وقشور التمن مع ا ً وزني الذي يؤثر يحسن من مقاومة البلى للمواد المتراكبة من البوليستر غير المشبعة بشكل كبير. لوحظ أن محتوى الحشو هو العامل الرئيسي الهام القنبليف ا ) تم الحصول على األمثل لمتغيرات البلى عند s/nج نسبة االشارة الى الضوضاء ((وقت االنزالق) و (الحمل العادي). ايضا من نتائ على معدل البلى يليه ) لتقليل معدل البلى.a10, a7, a6, a3العينات ( ريم و وسام6069 al-khwarizmi engineering journal, vo investigation the optimization roughness in free form surface reem s. kazaal* *department of production engineering and **department (received https://doi.org/10.22153/kej.2019.10.001 abstract the aim of this research is to investigation the optimization of the machining parameters (spindle speed, feed rate, depth of cut, diameter of cutter and number of flutes of cutter) material (aluminum 6061 reinforced boron carbide) the free-form surface. side milling (profile) purpose of using anfis to obtain the better prediction of surface value and get optimum machining parameters by using taguchi method 4500 r.p.m, 920mm/rev feed rate, 0.6mm depth of cut, 10mm diameter, 2 flute keywords: optimization, surface roughness, 1. introduction work has been done on composite material to achieve the best surface roughness relative to free form surfaces using end mill cutter on the side of the form by using vertical cnc milling machine. mustafa kurt et al. [1] for the purpose of pleasing customers, many free surface products are designed to enhance their aesthetic these products can have complicated surfaces to meet functional requirements, which necessitate specific aerodynamic, optical, medical, structural and processing characteristics. addressed the effects of factors on surface roughness and dimensional machining errors during free-form surface machining using experimental works using a ball-end mill in a 3 axis cnc milling machine. j.-m. redonnet [2] end-milling of free-form surfaces on 5 nc machine tools is a complex problem non-convex surfaces interference in end milling khwarizmi engineering journal, vol. 15, no. 2, june , (2019) p.p. 6069 e optimization of machining parameters n free form surface of composite material kazaal* wisam k. hamdan** *department of production engineering and metallurgy/ university of techno *department of biomedical engineering / university of technology *email: sabahreem18@yahoo.com **email: wisamuot@yahoo.com (received 16 july 2018; accepted 31 october 2018) https://doi.org/10.22153/kej.2019.10.001 the aim of this research is to investigation the optimization of the machining parameters (spindle speed, feed rate, depth of cut, diameter of cutter and number of flutes of cutter) of surface roughness for freematerial (aluminum 6061 reinforced boron carbide) by using hss uncoated flat end mill cutters which are rare use of form surface. side milling (profile) is the method used in this study by cnc vertical milling purpose of using anfis to obtain the better prediction of surface roughness values and decreased of the error prediction value and get optimum machining parameters by using taguchi method for the best surface roughness 920mm/rev feed rate, 0.6mm depth of cut, 10mm diameter, 2 flute. ptimization, surface roughness, free-form surface, composite material, taguchi method, milling machine. work has been done on composite material to relative to free cutter on the side of the form by using vertical cnc milling machine. the purpose of pleasing customers, many free surface products are designed to enhance their aesthetic appearance; have complicated surfaces to which necessitate specific aerodynamic, optical, medical, structural this study addressed the effects of factors on surface ional machining errors form surface machining using end mill in a 3m. redonnet et al. form surfaces on 5-axis is a complex problem when in end milling which causes a risk between surface the research based on which turn works to locate the tool and thus improve the position of the tool relative to the goals set for each probability [3] the goal behind this study that the specific type of iso-planar milling for both roughing and finishing, has developed a process algorithm an optimal surface for freeform surface. while the algorithm is proposed solution for milling, it can be easily appropriate to other types of milling strategy such as contour milling. both computer simulation and physical cutting experiments of the suggested method have convincingly demonstrated its makings over the traditional simple offset method. milling method with variable parameters suc speed, feed rate and diameter of cutter roughness more homogeneous with greater productivity relative to free form on the roughness measurement al-khwarizmi engineering journal machining parameters to surface f composite material hamdan** university of technology university of technology the aim of this research is to investigation the optimization of the machining parameters (spindle speed, feed rate, -form surface of composite flat end mill cutters which are rare use of vertical milling machine. the roughness values and decreased of the error prediction for the best surface roughness at spindle speed form surface, composite material, taguchi method, milling machine. between the tool and the the research based on the algorithms which turn works to locate the tool and thus improve the position of the tool relative to the ability. lufeng chen et al. the goal behind this study that the specific type planar milling for both roughing and finishing, has developed a process algorithm an optimal surface for freeform surface. while the algorithm is proposed solution for iso-planar milling, it can be easily appropriate to other types of milling strategy such as contour milling. both computer simulation and physical cutting experiments of the suggested method have convincingly demonstrated its makings over the simple offset method. rybicki [4] a milling method with variable parameters such as eed rate and diameter of cutter for surface roughness more homogeneous with greater productivity relative to free form surface. based measurement results for the reem s. kazaal experiments, many problems have been set necessity of the surface curvature pre from primary profile, necessity of 2d roughness assessment in two perpendicular directions shaghayegh shajari et al. [5] discussed the effect of employing different cutter path strategies on cutting force, surface texture, and machining time when ball end milling of low curv surface; have shown that the use of different cutter path strategies when finishing ball end milling of low curvature convex surfaces has more effects on the cutting forces, surface texture, and machining time. in general, radial cutter path appears will give its preferred results with respect to the homogenous surface composition and obtain less cutting forces. rodrigo henriques lopes da silva et al. [6] using a method tool path strategies on side milling with a vertical end mill. the main objective of this study is to evaluate the path’s effect on the cutting forces and roughness of the surface, and simultaneously the effect of milling parameters (cutting speed, feed, and path period). then apply experiments randomly and a taguchi method was applied and concludes that the trajectories of the tool significantly surface roughness. istvan szaloki studied surface roughness (ra, rz, rt, rp, rsm and effect feed on the material (aluminum metal matrix composite) at constant speed with three value of feed per tooth. the search results proved that the rz and rp parameters are more able to give the influence of the milling parameters on the quality of the surface. the aim from these studies to obtain the best parameters to less roughness for convex region in free form surface. 2. experimental equipments 2.1 materials composite material (aluminum reinforcement with 4% boron carbide) used in this work and prepared by stir casting method metal matrix composite express one of the significant composite because have various applications like automotive and aerospace industries due to superior properties with conventional alloy [8]. this m been inspected in general company for engineering inspection and rehabilitation (s.i.e.r)/ (lab. & e.i.dep.) for chemical composition shown in table (1). al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 61 ny problems have been set: necessity of the surface curvature pre-filtering from primary profile, necessity of 2d roughness assessment in two perpendicular directions. discussed the effect ploying different cutter path strategies on cutting force, surface texture, and machining time when ball end milling of low curvature convex have shown that the use of different cutter path strategies when finishing ball end milling of re convex surfaces has more effects on the cutting forces, surface texture, and machining time. in general, radial cutter path appears will give its preferred results with respect to the homogenous surface composition and obtain less o henriques lopes da silva method tool path strategies on side milling with a vertical end mill. the main objective of this study is to evaluate the path’s effect on the cutting forces and roughness of the surface, and simultaneously the effect of milling feed, and path period). then apply experiments randomly and a taguchi method was applied and concludes that the trajectories of the tool significantly effect on istvan szaloki et al. [7] ra, rz, rt, rp, rsm) on the material (aluminum metal matrix composite) at constant speed with three the search results proved that the rz and rp parameters are more able to give the influence of the milling parameters on the the aim from these studies to obtain the best parameters to less roughness for aluminumt-6061 reinforcement with 4% boron carbide) used in this and prepared by stir casting method. the metal matrix composite express one of the because have various applications like automotive and aerospace industries due to superior properties compared his material has been inspected in general company for engineering inspection and rehabilitation lab. & e.i.dep.) for chemical table 1, shown the chemical composition of (al+b4c) composite material. elements % elements si 0.756 cr fe 0.422 ni cu 0.309 zn mn 0.060 pb mg 0.88 ti v 0.008 b4c al bal. 2.2 machining cnc vertical milling based machine has been used to machining the composite material (al+b4c) hss end-mill cutter with different diameters (6, 8, and 10) mm; and number of flutes (2, 3, and 4).the machining (side milling) has been performed on free form surface shown in fig (1 various parameters spindle speed, feed rate , depth of cut , diameter of cutter and number of flutes of cutter under dry cutting condition better roughness of the free form surface because of the rare use of this type of tool to machine this surface . fig. 1. shown the design of free form the dimensions of the form as shown in figure (2) khwarizmi engineering journal, vol. 15, no. 2, p.p. 6069 (2019) hown the chemical composition of (al+b4c) elements % cr 0.206 ni 0.006 zn 0.013 pb 0.010 ti 0.023 b4c 4% c-tek (km-80 d) pc machine has been used to machining the composite material (al+b4c) by using uncoated mill cutter with different diameters (6, 8, and 10) mm; and number of flutes (2, 3, and 4).the machining (side milling) has been performed on hown in fig (1) dependent on various parameters spindle speed, feed rate , depth of cut , diameter of cutter and number of flutes of under dry cutting condition to obtain the better roughness of the free form surface because type of tool to machine this shown the design of free form surface. the dimensions of the form as shown in figure (2). reem s. kazaal fig. 2. shown the dimension of the form. 3. taguchi methods for designing experiments taguchi has developed a system for the application testing designed; this system the design of experiments from the exclusive world of the statistician and making them more visible in the world of manufacturing contributions of the system also made the user simpler in obtaining fewer tests in experimental designs [9]. taguchi submitted, the use of the loss function to measure the performance feature deviating from the required value, further convert into a signal-to-noise ratio. there are three the performance characteristic in the analysis of the signal-to-noise ratio (t better, the higher-the-better, and the nominal better) [10].in this study lower the better used to suggest of surface roughness in equation (1) � ���⁄ = �10 log ( ∑ ��� �� ) where: � ���⁄ : signal to noise ratio ���= observed value of the ��� experiment at the ��� test. n = number of observation in a trials. al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 62 fig. 2. shown the dimension of the form. taguchi methods for designing uchi has developed a system for the application testing designed; this system has taken the design of experiments from the exclusive and making them more visible in the world of manufacturing. the ibutions of the system also made the user simpler in obtaining fewer tests in experimental taguchi submitted, the use of the loss function to measure the performance feature deviating further convert into a three types of the performance characteristic in the analysis noise ratio (the lower-thebetter, and the nominalthelower the better was suggest of surface roughness in equation … (1) experiment at the s. 4. surface roughness measurement surface roughness was measured by using roughness measured device in fig (3) for 18 experiments designed according to the taguchi method orthogonal array with mixed levels� ��4 � � 1� used control parameters and their levels. fig. 3. roughness device (marsurfps1). table 2, the control parameters and their levels no. notation no.of level low value 1 a 6 2500 2 b 3 120 3 c 3 0.2 4 d 3 6 5 e 3 2 when: a: spindle speed, b: feed rate, c: depth of cut d: diameter of cutter, e: number of flutes the roughness has been measured for two areas (convex and concave) of free form surface shown in fig (4). khwarizmi engineering journal, vol. 15, no. 2, p.p. 6069 (2019) roughness measurement surface roughness was measured by using roughness measured device (marsurfps1) shown fig (3) for 18 experiments designed according to the taguchi method orthogonal array with ��; table (2) shows the parameters and their levels. roughness device (marsurfps1). he control parameters and their levels low value high value unit 2500 5000 r.p.m 120 920 mm/rev 0.2 0.6 mm 6 10 mm 2 4 a: spindle speed, b: feed rate, c: depth of cut d: diameter of cutter, e: number of flutes. the roughness has been measured for two areas (convex and concave) of free form surface reem s. kazaal fig. 4. the model of the work. the results obtained for the values of the roughness shown in table (3) found in convex area less than concave area as the diagram (1) described below. table 3, the roughness value in convex and concave areas no. a b c d e 1 2500 120 0.2 6 2 2 2500 520 0.4 8 3 3 2500 920 0.6 10 4 4 3000 120 0.2 8 3 5 3000 520 0.4 10 4 6 3000 920 0.6 6 2 7 3500 120 0.4 6 4 8 3500 520 0.6 8 2 9 3500 920 0.2 10 3 10 4000 120 0.6 10 3 11 4000 520 0.2 6 4 12 4000 920 0.4 8 2 13 4500 120 0.4 10 2 14 4500 520 0.6 6 3 15 4500 920 0.2 8 4 16 5000 120 0.6 8 4 17 5000 520 0.2 10 2 18 5000 920 0.4 6 3 ra.1: the roughness in convex surface. ra.2: the roughness in concave surface. al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 63 the results obtained for the values of the roughness shown in table (3) found in convex area less than concave area as the diagram (1) he roughness value in convex and concave areas ra.1 ra.2 1.123 1.423 4.510 5.140 1.660 1.128 4.091 5.130 0.966 1.081 2.052 1.650 2.745 3.166 1.038 1.067 2.214 2.27 2.581 3.592 4.576 3.462 1.436 1.312 1.063 1.073 1.506 1.568 1.076 1.424 1.381 1.590 0.806 1.145 1.747 4.159 ra.1: the roughness in convex surface. ra.2: the roughness in concave surface. fig. 5. shown the convex and concave 5. prediction by (anfis) adaptive network based fuzzy inference system means a fuzzy inference system perform in the framework of adaptive networks. soft computing oncoming including artificial neural networks and fuzzy inference have been used vastly to model expert attitude. using given input and output data, the suggest anfis can put up mapping depended on both human knowledge (in the form of fuzzy ifthen rules) and hybrid learning algorithm. in modeling and simulation, the anfis strategy is utilize to model nonlinear functio most important factor of machine and predict it. more effective, faster response the program consists of eight types of membership functions; each type contains two components constant and linear function thus becoming 16 fuzzy rules. in this study anfis in matlab software program the surface roughness to obtain more accurate values after it was found that the error value was very few among the practical and predictive experiments; through the experiments co through the training and testing date found the triangular membership function type and input of membership function =2; type 200 shown in figure (6) shown in table (4) the equation of error: error= |��� !" #!" $%&'$()��$( ��� !" #!" $ 0 1 2 3 4 5 6 1 3 5 7 9 11 (ra) value khwarizmi engineering journal, vol. 15, no. 2, p.p. 6069 (2019) shown the convex and concave roughness. prediction by (anfis) adaptive network based fuzzy inference system means a fuzzy inference system perform in the framework of adaptive networks. soft computing oncoming including artificial neural networks and fuzzy inference have been used vastly to model ing given input and output data, the suggest anfis can put up mapping depended on both human knowledge (in the form of fuzzy then rules) and hybrid learning algorithm. in modeling and simulation, the anfis strategy is utilize to model nonlinear functions, to control the most important factor of machine and predict it. effective, faster response [11]. the program consists of eight types of membership functions; each type contains two components constant and linear function thus in this study anfis tool in matlab software program was used to predict the surface roughness to obtain more accurate values after it was found that the error value was very few among the practical and predictive experiments; through the experiments conducted through the training and testing date found the triangular membership function type and input of 2; type linear and epochs found that is less error &'$()��$( #!" $| � 100% ... (2) 11 13 15 17 experiments convex concave reem s. kazaal fig. 6. shown the membership function and epochs used for table 4, shown the error percentage. no. of experiments actual value predict value 1 1.123 1.12 2 4.510 4.51 3 1.660 1.66 4 4.091 4.09 5 0.966 0.967 6 2.052 2.05 7 2.745 2.75 8 1.038 1.04 9 2.214 2.21 6. analysis of variance (anova) the anova performed to check the statistical significance of the process factors affecting the surface roughness through by separating the total variability of the s/n ratios, can be calculated by the total squared deviations from the total mean of the s/n ratio, into contributions by each of the process parameters and the error. carried out to judge the significant parameter al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 64 . shown the membership function and epochs used for predict. error % no. of experiments actual value 0.267 10 2.581 0 11 4.576 0 12 1.436 0.0244 13 1.063 0.103 14 1.506 0.0974 15 1.076 0.6711 16 1.381 0.192 17 0.806 0.1806 18 1.747 ariance (anova) the anova performed to check the statistical significance of the process factors affecting the surface roughness through by separating the total variability of the s/n ratios, can be calculated by the total squared deviations from the total mean of ratio, into contributions by each of the process parameters and the error. f-test was carried out to judge the significant parameter affecting the roughness. the larger f the ones that determine the most influential factor on performance. [12]. analyzing the results using main effect plot and sn ratio to know the affect each paramet from low to high level fig (7.a) and (7 main effect plot of surface roughness and for sn ratios in five graphs and affect the chosen five machining parameters on surface roughness of free form surface. khwarizmi engineering journal, vol. 15, no. 2, p.p. 6069 (2019) predict value error % 2.58 0.0387 4.58 0.0874 1.44 0.278 1.06 0.282 1.50 0.398 1.08 0.3717 1.38 0.0724 0.808 0.2481 1.75 0.1717 affecting the roughness. the larger f-value was the ones that determine the most influential factor analyzing the results using main effect plot and sn ratio to know the affect each parameter from low to high level fig (7.a) and (7.b) shows main effect plot of surface roughness and for sn ratios in five graphs and affect the chosen five ters on surface roughness of reem s. kazaal al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 6069 (2019) 65 fig. 7.a. main effect plot for mean. fig. 7.b. main effect plot for sn ratio. the effect of combination parameters and how to influence on the surface roughness can be shown by the interaction plot shown in fig (8). the minitab17 software program was used to create the anova which illustrates the most effective factors to reduce roughness as shown in table (5). 500 0 45 00 4000 350 0 30 00 2500 3.0 2.5 2.0 1.5 1.0 92 0 52 0 120 0. 6 0.40.2 1086 432 speed m e a n o f m e a n s feed doc dia flute main effects plot for means data means 50 00 4500 400 0 35 00 300 0 25 00 -1 -2 -3 -4 -5 -6 -7 -8 -9 920520120 0.60.40.2 1086 432 speed m e a n o f s n r a ti o s feed doc dia flute main effects plot for sn ratios data means signal-to-noise: smaller is better reem s. kazaal al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 6069 (2019) 66 fig. 8. interaction plot of parameters. table 5, analysis of variance results of convex region in free form surface source df adj ss adj ms f-value p-value contribution model 20 1084.06 54.203 59.21 0.000 linear 5 638.98 127.796 139.60 0.000 a 1 527.78 527.779 576.55 0.000 82.597% b 1 16.29 16.287 17.79 0.000 2.549% c 1 29.15 29.153 31.85 0.000 4.561% d 1 68.66 68.662 75.01 0.000 10.745% e 1 2.53 2.529 2.76 0.097 0.395% square 5 10.71 2.141 2.34 0.041 a*a 1 6.69 6.686 7.30 0.007 62.464% b*b 1 0.41 0.415 0.45 0.501 3.828% c*c 1 0.03 0.026 0.03 0.866 0.2801% d*d 1 2.90 2.899 3.17 0.076 27.077% e*e 1 0.67 0.675 0.74 0.391 6.255% 2-way interaction 10 438.73 43.873 47.93 0.000 a*b 1 4.96 4.964 5.42 0.020 1.1305% a*c 1 3.24 3.239 3.54 0.061 0.7384% a*d 1 7.90 7.902 8.63 0.003 1.8006% a*e 1 27.85 27.847 30.42 0.000 6.347% b*c 1 15.12 15.123 16.52 0.000 3.4463% b*d 1 152.38 152.378 166.46 0.000 34.731% b*e 1 8.00 7.998 8.74 0.003 1.823% c*d 1 0.43 0.429 0.47 0.494 0.0980% c*e 1 100.56 100.565 109.86 0.000 22.920% d*e 1 115.40 115.400 126.06 0.000 26.303% error 465 425.67 0.915 lack-of-fit 455 425.67 0.936 * * pure error 10 0.000 0.000 total 485 1509.73 100% reem s. kazaal al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 6069 (2019) 67 7. optimization by using taguchi method taguchi methods of experimental design provide a simple, effective and systematic approach for the optimization of experimental design for performance quality and for expected economic production. this method is a unique and powerful statistical experimental design technique, which greatly improves the engineering productivity [10]. through the roughness value in table (3) shown above that the roughness values in the convex region less than the concave region; therefore, the optimization has been performed in the convex region. table 6, the parameters and their levels levels parameters a b c d e 1 1 1 1 1 2 2 2 2 2 3 4 3 3 3 3 5 6 through the table (7) can be obtained the mean of ra.convex for sn. table 7, mean of ra for sn ratio level parameters a b c d e -6.198 -5.643 -5.988 -6.335 -2.209 -6.272 -5.365 -5.413 -5.157 -5.412 -8.208 -8.234 -1.721 -4.416 -4.327 -3.725 -5.055 -3.153 the large number was selected for all parameters in the table and take roughness values for the one level and divided on number of levels and applied in the equation (3) ra=a5+b3+c3+d3+e1-(n-1) t ... (3) where: n= number of parameters. t= the mean of the trails. ra=0.7101+,. 8. the result and discussion the analysis of variance can be used to identify the effect of factors in reducing surface roughness and obtaining a highquality surface after showing the model summery in the table (8) below; the convergence between practical r-sq and predictive r-sq (adj) experiments was very large and thus can be depended on the results of the analysis of variance (anova) table. table 8, model summary. s r-sq r-sq (adj) r-sq (pred) 0.956772 71.81% 70.59% 68.61% through the analysis of variance (anova) table found the factor that affects a large amount to reduce the surface roughness in convex area of free form surface is spindle speed at 4500 r.p.m .this also has been found through main effect plot where the effect of influence 82.597%.through the interaction when combination between two parameters found the fisher test value (f-value) at (b*d)=166.46 that represent a large value this means that feed rate and diameter of cutter are considered important parameters to less the surface roughness in convex area to free form surface where was the feed rate 920 mm/rev and (10 mm) diameter cutter were the best related roughness and its ratio 34.731% and it is fluent in diameter with flutes ;(2) flute express the better compared with other flutes . 9. conclusion in this study shown: 1. the more influential parameters to obtain the surface roughness in free form surface at convex area in composite material are spindle speed (4500 r.p.m) and number of two flutes when the cutting area is constant and heat a few because it is a beginning to cut and not to be built up edge on the edge of cutter and we can conclude that the diameter of cutter when increase the surface roughness decreased. 2. from the optimization by taguchi method found that the best machining parameters at spindle speed (4500 r.p.m), feed rate (920 mm/rev), depth of cut (0.6mm), diameter of cutter (10mm) and number of flute (2) to obtain the best surface roughness. reem s. kazaal al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 6069 (2019) 68 10. reference [1] mustafa kurt, selim hartomacýoð, bilçen mutlu,uður köklü” minimization of the surface roughness and for merror on the milling of free-form surfaces using a grey ralational analysis” original scientific article,pp.205-213, 2012. [2] j.m. redonnet, w. rubio, f. monies and g. dessein” optimising tool positioning for end-mill machining of free-form surfaces on 5-axis machines for both semi-finishing and finishing” international journal advancing manufacturing technol,2000. [3] lufeng chen, pengcheng hu, ming luo, kai tang “optimal interface surface determination for 4 multiaxis freeform surface machining with 5 both roughing and finishing”, chinese journal of aeronautics, pp.15,2017. [4] m rybicki” problems during milling and roughness registration of free-form surfaces”, journal of physics, 2014. [5] shaghayegh shajari, mohammad hossein sadeghi, and hamed hassanpour,” the influence of tool path strategies on cutting force and surface texture during ball end milling of low curvature convex surfaces”, the scientific world journal, pp.14,2014. [6] rodrigo henriques lopes da silva & amauri hassui1” cutting force and surface roughness depend on the tool path used in side milling: an experimental investigation”, the international journal of advanced manufacturing technology, 2018. [7] istván szalóki, sándor sipos, zsolt jános viharos “aluminum-based mmc machining with carbide cutting tool” icpm 2015 congress 8th international congress on precision machining, pp.151-156,2015. [8] s jeyakumar, k marimuthu &t ramachandran “optimization of machining parameters of al6061 composite to minimize the surface roughness-modelling using rsm and ann’’indian journal of engineering & materials sciences, vol.22, pp.29-37,2014. [9] m. nalbant, h.go¨kkaya, g. sur” application of taguchi method in the optimization of cutting parameters for surface roughness in turning”, materials and design journal, 2007. [10] s.s.chaudhari, s.s. khedkar , n.b. borkar,” optimization of process parameters using taguchi approach with minimum quantity lubrication for turning”, international journal of engineering research and applications (ijera), vol. 1, issue 4, pp.1268-1273. [11] navneet walia, harsukhpreet singh, anurag sharma” anfis: adaptive neuro-fuzzy inference systema survey”, international journal of computer applications, vol.123, no.13, august 2015. [12] kompan chomsamutr, somkiat jongprasithporn” optimization parameters of tool life model using the taguchi approach and response surface methodology”, ijcsi international journal of computer science issues, vol. 9, issue 1, no 3, 2012. )2019( 6069، ! � 2د، ا�������15 ا���ارز � ا������� ا���� ر� ��ح ���� 69 '��&أ$ #�" � (�)� �����اد ا���01 ة.� ا�-,�ح ا���#� �ا�-, � ����ا � ا�+(*�� �� **و��م �0ظ ��3ان *ر� ��ح ���� =>.اد/ ا%#;اق/ ,ا%(8/9%678 ,ا%5"4# /123 ھ/.-, ا+*("ج وا%$#"دن* sabahreem18@gmail.com * .>;?%ا+%9(;و*@ا: wisamuot@yahoo.com :@*ا%?;<. ا+%9(;و** 7� �ا� 6ab4+ا c6def g%ا he?%ا اiف ھ.k>, l6<m)%ا l48ا#% )nod%ا ,p;و>i<)%و ,4#.ل اnod%ا c$p ط#و"d%ود ا.e%د ا.pا+داة و ;o3, ا%#. ةا%$878د @tة( *8mua%, 6eo2%2? ,ا/%"=, .d#$%8ح اo2a%ة ?w;$%8اد ا$a%, ) 1 =9"ر=6. ا%?8رون ٦٠٦١-?96, ا%$/86مp.4 (-8=" ]6t;ا^?#6[ ط _>;`f no3 ام ادوات.u)-ط, ا $t "k= l@ ھiه ا%(`;<_ ا%5"*?@ ھ@ ط;<1f l6<mf ,d ا%#و ةا%(@ 89fن *"درة ا+-(u.ام n4 ا8o2%ح ا%$#ba^ c4 ]p8/d4 ]6ao4 ;6e, .d اp;2%"ت ا%#"6% ,ا6eo2%, و3. ا-(u.م *j"م ا+-(.+ل ا%>"i4 ا%#d?@ ا%(8dea% @`69ل gap اlht ا%(/?gات %16d ا%8mu* ,ا%;w, 6$3/, ا%(`;<_ ا%#$8د<"="-(u.ام 4 ,ا%.را4#.ل ،,دd63 /دوره ٤٥٠٠-78w"f ,d@ m*8ml lht, no3 ,p;./p ]6eo<وا%(kol c4 l6ad ا%(/?g وا%8deل 8p gapاl6<mf l4 اu)-"= lb4.ام ط; >i<)%دوره/14 ٩٢٠ ,ا، nod%ا c$p٠.٦ 14، ا+داة ;o3١٠ 14،ط# ٢"d%ود ا.e%ا c4, . this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 21, no. 1, march (2025), pp. 28-34 impact loading rate measuring with different heel shoe design for transtibial amputation hamza abbas department of biomedical engineering, college of engineering, university of al-nahrain, baghdad, iraq email: hamza.abbas@nahrainuniv.edu.iq (received 29 october 2023; revised 6 august 2024; accepted 1september 2024; published 1 march 2025) https://doi.org/10.22153/kej.2025.09.001 abstract humans experience impact peaks due to the repetitive pressures placed beneath the heel during walking, and these peaks are marked by high rates and magnitudes of loading. momentum is transferred from the ground to create impact peaks at the effective mass to the part of the body that stops moving at that point. the stiffness of the heel affects impacts generated by that momentum. this study aims to improve our understanding of how the body produces impact peaks and how the stiffness and features of the shoe heel affect parameters such as peak magnitude (fmax) and impact loading rate (f'). a shoe heel model is presented, and walkers wearing less stiff foot heels are expected to have less effective mass and vertical impulse. a human amputee adult male participated in evaluating the model by walking in 15 different heel designs. minitab software, which applies response surface approach, was used to acquire the shoe’s design properties. the subject walked on a force plate while 3d kinematic data were collected. design of experiment was carried out using minitab software to determine the optimal shoe heel design (depending on material and shape) that reduces the impacting effect. statistical results show that heel height has a more significant effect (p=0.053) on impact loading rate than elastic modulus and cross-sectional area. according to the optimisation results based on the response surface design, wearing a heel with a modulus of elasticity of 0.5864 mpa, an area of 60.0 cm2 and a height of 0.50 cm may help improve the amputee's gait. keywords: anova; doe; impact loading rate; minitab; rsm 1. introduction every time a person walks or runs and their heel becomes in contact to the ground, their foot experiences a tremendous amount of force known as ‘peaks’. these ‘peaks’ occur when a specific area of the body has a brief (often between 10 and 50 ms) temporary shift in energy. much controversy exists with regard to whether or not these sorts of forces might result in repetitive stress injuries; nevertheless, many studies were conducted on mechanisms underlying the production of these forces and the extent to which they are impacted by the surrounding environment [1–8]. several studies examined how an individual’s footwear influences the forces of impact that their body experiences. many people believe that by wearing shoes with varying degrees of stiffness, they might lessen the possibility of experiencing discomfort and injury from potential impact peaks while they move. [3,9]. a number of experimental and theoretical research on the subject indicates that softer shoe heels result in a decline in f' that is mostly due to an increase in the time interval (t) between impacts rather than an alteration in fmax [10–14]. researchers also examined the connection between a factor called fmax and the stiffness of shoe heels, but the findings are not obvious and unambiguous [15]. some studies found that the stiffness of the heel raised fmax, while other studies reported opposite results. moreover, the stiffness of the heel was found to have no correlation at all with fmax [4,16–18]. modelling studies are academic enquiries that model an mailto:hamza.abbas@nahrainuniv.edu.iq https://doi.org/10.22153/kej.2025.09.001 hamza abbas al-khwarizmi engineering journal, vol. 21, no.1, pp. 2834 (2025) 29 environment or process using mathematical equations. according to a report, these simulations suggest that the stiffness of a shoe’s heel should minimise the force needed to execute any task (fmax) and that muscular activity in the lower body may also have an effect. after observing that the loading rate during walking in one transtibial amputee was higher in the intact limb than in the prosthetic limb, researchers hypothesised that the loading variables in the intact limb would be greater than in the prosthetic limb [19–21]. a statistical methodology known as design of experiments (doe) was employed to systematically plan and execute tests to gather data and investigate the effects of different components on a process or system. this tool creates a plan for the experiment that includes several treatments or conditions and a system for randomly assigning those treatments to the experimental units [25,26]. doe seeks to identify the components that have the most impact on a process or system and determine the ideal amount of such factors to achieve the desired results [22–24]. data were gathered and analysed using statistical techniques to gauge the effect of each therapy on the desired goal. overall, doe is an effective technique used to comprehend and improve intricate systems and procedures. instead of relying on instinct or guesswork, it enables academics and practitioners to make knowledgeable decisions based on factual evidence [27–30]. this study aims to improve our understanding of how the body produces impact peaks and how the stiffness and features of the shoe heel affect three parameters: peak magnitude (fmax), impact loading rate (f') and vertical impulse. these parameters have been associated with the start of several musculoskeletal disorders. gait analysis was conducted by evaluating videos and selecting the optimal material for the shoe heel on minitab to determine the optimum shoe heelwearing design for transtibial amputation. 2. materials and methods 2.1 subject an adult male with body mass of 83 kg, height of 185 cm and age of 36 years who suffered from transtibial amputation participated in the experiment. the experiment was conducted in the department of biomedical engineering laboratory. the methodology was approved by the ethical committee of al-nahrain university. the subject has to be able to heel strike while walking for the whole 30-second trial period on all foot heel pads and meet other requirements (walk straight with own speed and without assistive devices). three materials with different moduli of elasticity (table 1) were used in the design of shoe heels. they had two polymer bases but with different physical characteristics according to the data sheets provided by the manufacturer (soudal international). table 1, materials used and their modulus of elasticity elasticity modulus bases material names 0.35 mpa polysiloxane gasketseal 0.80 mpa polyurethane soudaflex 40fc 0.50 mpa polysiloxane silirub no5-he the experiment was carried out with the following steps: step 1 preparation of shoes: the heels were created in accordance with the measurements generated by minitab software (table 2). fifteen shoes were designed with different dimensions of the heel area, and the proper heel height was determined. three heel cuts were created with heights of 0.5, 0.87 and 1.25 cm. a mould was created to cast the desired material. figure 1 shows the preparation steps from measurement up to cutting and casting for the suggested design. the steps were repeated for all 15 designs suggested by minitab software. fig. 1. preparation of shoes. starting from cutting the entire heel area and re-casting it with the used materials, according to the dimensions and areas given by the program. hamza abbas al-khwarizmi engineering journal, vol. 21, no.1, pp. 2834 (2025) 30 table 2, design characteristics of shoe heels suggested by minitab. design name e (mpa) a (cm2) l (cm) a1 0.35 53.7 1.25 a2 0.35 53.7 0.5 a3 0.35 60 0.875 a347 0.35 47.4 0.875 b1 0.575 60 0.5 b147 0.575 47.4 0.5 b2 0.575 53.7 0.875 b2 0.575 53.7 0.875 b2 0.575 53.7 0.875 b3 0.575 60 1.25 b347 0.575 47.4 1.25 c1 0.8 53.7 0.5 c2 0.8 60 0.875 c247 0.8 47.4 0.875 c3 0.8 53.7 1.25 step 2a force plate test was conducted, with three trials for each model. the patient was told to walk correctly and with planned steps to obtain the best results and prevent any possible errors. the lower limb ground response forces during the impact peak were measured and identified as the initial vertical force peak. the amti force plate contains six transducers to measure the displacement of the upper surface in 1 minute on all three axes when force is applied vertically to the surface of the device. 2.2. impact loading rate (f`) calculations impact peak magnitude (fmax) can be obtained from the data collected from the force plate and represents the first peak on the gait cycle diagram (figure 2). impact loading rate (f`) can be calculated by dividing the value of fmax on the time from the beginning of the curve (heel strike) to the first peak (fmax) [18]. fig. 2. vertical ground reaction force estimated impact peak magnitude. [18] 2.3. data analysis statistical software minitab (minitab 18) was utilised to perform regression and anova. the chosen dominating parameters were subjected to anova to evaluate the performance of the secondorder model for each response of the machining process. the null hypothesis stated that the observed values were random and was tested using anova with a 95% confidence level. fisher's statistical test (f-test) was used to determine the parameter's significance, and a high result denotes high relevance. if the p-value is less than 0.05, then the factor's influence is considered statistically significant [32]. 3. results and discussion numerous studies were performed to investigate the impacts of input variable parameters on responses to determine the degree to which these factors influence the walking pattern and identify the most significant of the components. the characteristic values for fmax and f' are tabulated in table 3. regression analysis was conducted to analyse the connection between the input variable parameters and the responses. a general secondorder model was developed using rsm based on mathematical formulations developed using the experimental data. equations (1) and (2) serve as an example of how the mathematical models for various necessary performance measures were created 𝑭` = −𝟏𝟎𝟎𝟑𝟏 + 𝟖𝟔 𝑬 + 𝟓𝟏𝟎 𝑨 − 𝟏𝟐𝟎𝟖 + 𝟑𝟏𝟑𝟎 𝑬 ∗ 𝑬 − 𝟒. 𝟔𝟑 𝑨 ∗ 𝑨 + 𝟓𝟔𝟓 𝑳 ∗ 𝑳 − 𝟓𝟓. 𝟏 𝑬 ∗ 𝑨 − 𝟏𝟏𝟏𝟎 𝑬 ∗ 𝑳 𝑭𝒛 𝒎𝒂𝒙 = 𝟏𝟒𝟔𝟒 + 𝟐𝟗𝟖 𝑬 − 𝟐𝟓. 𝟔𝟖 𝑨 − 𝟒𝟕. 𝟐 𝑳 − 𝟑𝟗. 𝟖 𝑬 ∗ 𝑬 + 𝟎. 𝟐𝟔𝟓𝟎 𝑨 ∗ 𝑨 + 𝟓𝟗. 𝟓 𝑳 ∗ 𝑳 − 𝟑. 𝟔𝟕 𝑬 ∗ 𝑨 the goodness of fit of the second-order regression model was evaluated using the coefficient of determination (r2) function. the values of (r2) and (r2adj), for all previously constructed mathematical models, are 89.23% and 90.17%, respectively. hamza abbas al-khwarizmi engineering journal, vol. 21, no.1, pp. 2834 (2025) 31 table 3, characteristic values for fmax and f' run order r f max (bw) f` (bw/s) 1 a1 836.045 3800.20 2 a2 841.962 3238.32 3 a3 852.317 3278.14 4 a347 837.264 3220.25 5 b1 858.234 3065.12 6 b147 859.714 3070.41 7 b2 838.047 3223.26 8 b2 838.047 3223.26 9 b2 838.047 3223.26 10 b3 850.403 3270.78 11 b347 859.366 3069.16 12 c1 860.410 3309.27 13 c2 845.443 3019.44 14 c247 851.186 3273.79 15 c3 839.178 3496.58 table 4 shows the anova findings for all responses, including sr and wlt. the p-value, mean square (ms), f-test, degree of freedom (df) and sum of squares (ss) are included. table 4, anova for f` response. source df adj ss adj ms fvalue pvalue model 9 397049 44117 1.43 0.361 linear 3 234126 78042 2.54 0.170 e 1 14653 14653 0.48 0.521 a 1 23434 23434 0.76 0.423 l 1 196039 196039 6.37 0.053 square 3 144385 48128 1.56 0.308 e*e 1 111455 111455 3.62 0.115 a*a 1 856 856 0.03 0.874 l*l 1 37521 37521 1.22 0.320 2-way interaction 3 18538 6179 0.20 0.892 e*a 1 565 565 0.02 0.898 e*l 1 4652 4652 0.15 0.713 a*l 1 13321 13321 0.43 0.540 error 5 153774 30755 lack-offit 3 153774 51258 * * pure error 2 0 0 total 14 550822 figure 2 demonstrates the primary effect plot for the controllable factors on f'. the height of the heel may be regarded as the most essential parameter among all the variable factors (table 3). figure shows that e, a and l have a considerable impact on f'. this graph illustrates the relationship between f' and l. the most important influencing element is the height of the heel, which displays a dramatic increase in the f' mean value (246.02) (bw/s) as the heel height increases from 0.875 cm to 1.25 cm. as illustrated in figure 2, the f` decreased by 19.29, the area of the heel increased from 47.4 cm2 to 53.7 cm2 but decreased by (88.96) (bw/s) when the area increased from 53.7 cm2 to 60 cm2. the f decreased by 210.42 (bw/s), the modulus of elasticity increased from 0.35 mpa to 0.57 mpa and slightly increased by 124.83 (bw/s) when e increased from 0.57 mpa to 0.80 mpa). fig. 2. main effects plot for impact loading rate. the x-axis shows the effect of height (l, in cm), area (a, in cm2) and modulus of elasticity (e in mpa) on changing the mean of impact loading rate f' (bw/s). the combined effects of area, height and modulus of elasticity on f' are shown in figure 3. optimisation was carried out using desirability function analysis (dfa), which incorporates response surface methodology. in f', the goal of optimisation is often reached at the minimal values of other responses; in the present study, the major purpose is to enhance the amputee’s walking pattern and comfort during extended walks. fig. 4 shows the ideal set of solutions with greater desirability functions under the above restrictions. the optimal solution's parameters for (1)'s highest desirability criterion are modulus of elasticity = 0.5864 mpa, area =60.0 cm2 and height =0.50 cm. hamza abbas al-khwarizmi engineering journal, vol. 21, no.1, pp. 2834 (2025) 32 fig. 3. combination effects on impact loading rate (a) e; l vs f` (hold a=53.7). (b) e; a vs f` (hold l=0.875). (c) a; l vs f` (hold e=0.575). fig. 4. multi response optimisation by dfa. the upper left corner and top row display the composite desirability d. each of the remaining rows represents a response variable. the numbers at the top of each column represent the maximum and lowest modulus of elasticity variable settings employed in the experimental design. the columns stand for different variables, while the vertical red lines indicate the modulus of elasticity settings. not to mention, the most current answer values are shown by the blue horizontal lines. 4. conclusions in light of the experimental findings, the conclusions are as follows:  the results have been greatly influenced by the choice of input parameters.  the created model exhibits high predictive accuracy when applied to the experimental data.  the impact loading rate is strongly influenced by the height (the slight increase in the mean of f` of 246.02 bw/s) and elastic modulus than by other factors.  the optimal heel design can be obtained using modulus of elasticity of 0.5864 mpa, area of 60.0 cm2 and height of 0.50 cm to provide the lowest impact loading rate and reduce impact during the heel strike, leading to a comfortable gait with less impact side effect on the knee joint. references [1] y. folman, j. wosk, a. voloshin, and s. liberty, 1986."cyclic impacts on heel strike: a possible biomechanical factor in the etiology of degenerative disease of the human locomotor system," archives of orthopedic and traumatic surgery, vol. 104, pp. 363-365. 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[16] e. m. h. lafortune m. a., and m. j. lake, 1996 "dominant role of interface over knee angle for cushioning impact loading and regulating initial leg stiffness," journal of biomechanics, vol. 29, no. 12, pp. 15231529. [17] a.-m. l. wakeling j. m., and b. m. nigg, 2003 "muscle activity reduces soft-tissue resonance at heel-strike during walking," journal of biomechanics, vol. 36, no. 12, pp. 1761-1769. [18] b. j. addison and d. e. lieberman, "tradeoffs between impact loading rate, vertical impulse and effective mass for walkers and heel strike runners wearing footwear of varying stiffness," journal of biomechanics, vol. 48, no. 7, pp. 1318-1324, 2015. [19] t. e. o. m. s. a. d. o. s. i. f. p. d. r. nigg b. m. and w. liu, " journal of biomechanics, vol. 32, no. 8, pp. 849-856. [20] m. m. a. t. s. t. e. o. f. o. t. i. f. a. v. o. t. h. b. d. r. zadpoor a. a. and a. a. nikooyan. 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(2025) 28-34، صفحة 1، العدد21مجلة الخوارزمي الهندسية المجلد حمزة عباس فاضل 34 قياس معدل الصدمة لتصاميم مختلفة لكعب حذاء لمبتور تحت الركبة حمزة عباس فاضل رين، بغداد، العراقهقسم هندسة الطب الحياتي، كلية الهندسة، جامعة الن hamza.abbas@nahrainuniv.edu.iq البريد االلكتروني: المستخلص . يتم ن ل المخم من للتحايلبسررربب الطرررغتك الاتكري التي تت رررع لث الكعب شيناو الاشررري، والتي تتايم باعدال وقيم صرررطدا يتعرض البشرررر ل ام اال ند الكتلة الفعالة، شو جمو الجسررم ال ي يتتقع ن الحركة ند تلا الن طة. ياكن شي يكتي لتبادا المخم بين د شكرات تييير قام الصرردما األيض إلنشرراو هدت ه ه الدياسرررة لث تحسرررين فهانا لكيفية نتام الجسرررم ل ام االصرررطدا وكيع تاير صررر بة وخصرررا كعب لث ه ا، باا في ذلا صررر بة شة ية الكعب. ، يتم ت ديم وت ييم ناتذم كعب الح او، ومن الاتتقع شي يكتي لد الاشرررا '(f(، ومعدا قت االصرررطدا fmaxلث معلاا : قاة االصرررطدا الكبر الح او 15ن خ ا الاشي في لت ييم ه ا الناتذم م الطرت األسفلذكر بالغ مبتتي االستعانة باتطتع. تم اقلال ين يرتدوي كعتبًا شقل ص بة كتلة فعالة ونبطة يشسية ياشرري لث الاتطتع، ال ي يطبق نه سررطا االسررتجابة، للحصررتا لث خصررا تصررايم الح او. كاي minitabتصررايًاا ملتلفًا للكعب. تم اسررتلدا برنام مر شخر minitabباسررررررتلدا برنام ( doeي يية األبعاد. يتم جراو تصررررررايم ملالي للتجربة ال ت والعمو شيناو جاع بيانا جهاز قياس قت يد الفعل شي ايتفاع minitab. تظهر النتا اإلةصررا ية لبرنام صررطدا قت اال( ال ي ي لل من تييير االبعادالقتراح شفطررل تصررايم لكعب الح او ا تاادًا لث الااد و م اينة باعامل الارونة ومسرررراةة الا طع العر رررري. وف ًا لنتا التحسررررين ال ا اة لث صررررطدا قت اال( لث معدا p = 0.053الكعب له تييير شكلر شهاية سم قد يسا د في تحسين مشية الابتتيين. 0.50وايتفاع 2سم 60.0ميجا باسكاا ومساةة 0.5864تصايم سطا االستجابة، فإي ايتداو كعب باعامل مرونة mailto:hamza.abbas@nahrainuniv.edu.iq abstract 1. introduction 2. materials and methods the heels were created in accordance with the measurements generated by minitab software (table 2). fifteen shoes were designed with different dimensions of the heel area, and the proper heel height was determined. three heel cuts were created with he... fig. 1. preparation of shoes. starting from cutting the entire heel area and re-casting it with the used materials, according to the dimensions and areas given by the program. table 2, design characteristics of shoe heels suggested by minitab. step 2a force plate test was conducted, with three trials for each model. the patient was told to walk correctly and with planned steps to obtain the best results and prevent any possible errors. the lower limb ground response forces during the impa... 2.2. impact loading rate (f`) calculations impact peak magnitude (fmax) can be obtained from the data collected from the force plate and represents the first peak on the gait cycle diagram (figure 2). impact loading rate (f`) can be calculated by dividing the value of fmax on the time from the... fig. 2. vertical ground reaction force estimated impact peak magnitude. [18] 2.3. data analysis statistical software minitab (minitab 18) was utilised to perform regression and anova. the chosen dominating parameters were subjected to anova to evaluate the performance of the second-order model for each response of the machining process. th... 3. results and discussion numerous studies were performed to investigate the impacts of input variable parameters on responses to determine the degree to which these factors influence the walking pattern and identify the most significant of the components. the characteristic v... equations (1) and (2) serve as an example of how the mathematical models for various necessary performance measures were created 𝑭`=−𝟏𝟎𝟎𝟑𝟏 + 𝟖𝟔 𝑬 + 𝟓𝟏𝟎 𝑨 − 𝟏𝟐𝟎𝟖+ 𝟑𝟏𝟑𝟎 𝑬∗𝑬 − 𝟒.𝟔𝟑 𝑨∗𝑨 + 𝟓𝟔𝟓 𝑳∗𝑳 − 𝟓𝟓.𝟏 𝑬∗𝑨 − 𝟏𝟏𝟏𝟎 𝑬∗𝑳 + 𝟐𝟏.𝟗 𝑨∗𝑳………………... (𝟏) 𝑭𝒛 𝒎𝒂𝒙 = 𝟏𝟒𝟔𝟒 + 𝟐𝟗𝟖 𝑬 − 𝟐𝟓.𝟔𝟖 𝑨 − 𝟒𝟕.𝟐 𝑳 − 𝟑𝟗.𝟖 𝑬∗𝑬 + 𝟎.𝟐𝟔𝟓𝟎 𝑨∗𝑨 + 𝟓𝟗.𝟓 𝑳∗𝑳 − 𝟑.𝟔𝟕 𝑬∗𝑨 − 𝟒𝟓.𝟒 𝑬∗𝑳 − 𝟎.𝟕𝟗 𝑨∗𝑳………… (𝟐) the goodness of fit of the second-order regression model was evaluated using the coefficient of determination (r2) function. the values of (r2) and (r2adj), for all previously constructed mathematical models, are 89.23% and 90.17%, respectively. table 3, characteristic values for fmax and f' table 4 shows the anova findings for all responses, including sr and wlt. the p-value, mean square (ms), f-test, degree of freedom (df) and sum of squares (ss) are included. figure 2 demonstrates the primary effect plot for the controllable factors on f'. the height of the heel may be regarded as the most essential parameter among all the variable factors (table 3). figure shows that e, a and l have a considerable impact ... fig. 2. main effects plot for impact loading rate. the x-axis shows the effect of height (l, in cm), area (a, in cm2) and modulus of elasticity (e in mpa) on changing the mean of impact loading rate f' (bw/s). the combined effects of area, height and modulus of elasticity on f' are shown in figure 3. optimisation was carried out using desirability function analysis (dfa), which incorporates response surface methodology. in f', the goal of optimisation is of... fig. 3. combination effects on impact loading rate (a) e; l vs f` (hold a=53.7). (b) e; a vs f` (hold l=0.875). (c) a; l vs f` (hold e=0.575). fig. 4. multi response optimisation by dfa. the upper left corner and top row display the composite desirability d. each of the remaining rows represents a response variable. the numbers at the top of each column represent the maximum and lowest modul... 4. conclusions references قياس معدل الصدمة لتصاميم مختلفة لكعب حذاء لمبتور تحت الركبة حمزة عباس فاضل قسم هندسة الطب الحياتي، كلية الهندسة، جامعة النهرين، بغداد، العراق البريد الالكتروني: hamza.abbas@nahrainuniv.edu.iq المستخلص يتعرض البشر لقمم الاصطدام بسبب الضغوط المتكررة التي توضع على الكعب أثناء المشي، والتي تتميز بمعدلات وقيم للتحميل. يتم نقل الزخم من الأرض لإنشاء قمم الصدمات عند الكتلة الفعالة، أو جزء الجسم الذي يتوقف عن الحركة عند تلك النقطة. يمكن أن يكون لتبادل الزخم... this is an open access article under the cc by license : al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 21, no. 3, september, (2025), pp. 48–54 autonomous vehicle steering-based feedback linearization and sliding mode control anssam yahya kames1, ali hussien mary2*, laith awda kadhim mayyahi3, and oday al-jerew4 1,2 department of mechatronics engineering, al-khwarizmi college of engineering, university of baghdad, baghdad, iraq 3carleton university, faculty of engineering and design, ottawa, canada 4asia pacific international college, sydney, nsw 2150, australia *corresponding author’s email: alimary76@kecbu.uobaghdad.edu.iq (received 16 september 2024; revised 8 january 2025; accepted 26 may 2025; published 1 september 2025) https://doi.org/10.22153/kej.2025.05.002 abstract this study proposes a robust control approach for vehicular dynamic system speed control. the proposed method combines a sliding mode controller with a feedback linearization technique. considering the high nonlinearity of the vehicle dynamic system model, feedback linearization is used to transform the vehicle dynamic system into a linear system. a lyapunov theorem is used to approve the stability of the proposed controller. moreover, a proportional integral derivative (pid) controller with genetic algorithms is used for comparison. the integral absolute error (iae) is used as the performance comparison index between controllers. simulation results show that the proposed method can achieve excellent performance with high robustness against external disturbance and system uncertainty. in the tracking case, the iae value of the proposed controller is 2.3, whilst that of the pid is 15.2. under external disturbance, the iae values are 3.1 and 19.1 for the proposed controller and pid, respectively. keywords: feedback linearization; robust control; smc. 1. introduction in recent years, automotive and road safety has become a crucial focus in the development of vehicle control, monitoring systems and driving assistance technologies. all advanced driver assistance systems (adass) aim to improve driving safety and vehicle control by facilitating human–machine interaction [1, 2]. adas includes various types, including adaptive cruise control (acc), blind spot detection, automated parking, pedestrian safety systems, and anti-lock brakes [3, 4]. acc is one of the important assistance systems, as it enhances driver and passenger comfort by reducing driver fatigue. moreover, acc enhances safety by using sensors for monitoring [5]. acc maintains the vehicle speed as set by the driver without requiring throttle input whilst also ensuring a safe distance from other vehicles or obstacles. the acc system consists of two-sub control systems: speed control and distance control. the transition between these two sub system must be smooth and comfortable [6]. pid control is widely used in various control systems [7]. a pid controller adjusts the control inputs based on the proportional, integral and derivative components of the error signal to maintain a constant vehicle speed or following distance, regardless of uncertainties in the system dynamics [8]. given the ability of model predictive control (mpc) in handling complex constraints and predict future vehicle states, it is used to maintain the mailto:alimary76@kecbu.uobaghdad.edu.iq https://doi.org/10.22153/kej.2025.05.002 anssam yahya kames al-khwarizmi engineering journal, vol. 21, no.3, pp. 4854 (2025) 49 desired speed and safe distances from obstacles, ensuring comfort and safety [9]. fuzzy logic control can approximate complex systems using fuzzy rules [10], which has motivated a number of researchers to use it in designing acc systems that adapt to various driving conditions through flexible control strategies [11]. artificial neural networks have been used to model the dynamics of complex vehicles using real-time data [12]. this adaptive neural network can enhance the performance of the acc system by effectively responding to various cases, such as changing traffic conditions and diverse driving environments [13]. this adaption makes the acc system highly robust against varying conditions and disturbances [14]. pratama mahadika et al. [15] used an ann in the inner loop of an acc system using model predictive control. the ann is used to model the vehicle dynamics, whilst the mpc minimises the errors between the estimated outputs and the future reference trajectories. victoria oguntosin and jamiu olasina [16] utilised root locus and frequency domain methods to analyse the proposed linear cruise control system. the proposed control method was designed to meet the following specifications: a steady-state error of less than 1%, an overshoot of less than 5% and a rise time of less than 1.5 s. the results showed that the proposed control method successfully satisfied these criteria. trieu minh vu et al. [17] proposed a control method that integrates neural networks with the mpc, taking into account the hard and soft constraints to determine control actions whilst ensuring system stability. the simulation results demonstrated the excellent performance of the proposed control method across various trajectories. this study aims to present a reliable control system for regulating vehicle speed. the proposed control method combines feedback linearization and smc to simplify the control of the vehicle’s nonlinear dynamics. feedback linearization is used to obtain a linear dynamic system. thereafter, smc is applied to control the linear system. the stability of the proposed control method is verified using lyapunov’s second method. finally, the performance of the proposed control method is evaluated and compared with that of a pid controller using matlab/simulink software. 2. dynamic model newton’s second law is used to model the longitudinal dynamics of the vehicle, where the net tractive force, aerodynamic drag, rolling resistance and road grade determine the vehicle’s acceleration. the vehicle’s dynamic system can be modelled using newton’s second law, which relates the vehicle’s acceleration to the net force acting on it (fig. 1) [18]. fig. 1. gravitational forces 𝑚 𝑑𝑣(𝑡) 𝑑𝑡 = 𝐹𝑡𝑟(𝑡) − 𝐹𝑟(𝑡), …(1) where 𝑚 is the vehicle mass (kg), 𝑣(𝑡) the vehicle speed (m/s), 𝑑𝑣(𝑡) 𝑑𝑡 is the vehicle acceleration (m/s2), 𝐹𝑡𝑟(𝑡) is tractive force (n), and 𝐹𝑟(𝑡) is the resistive force (n). the resistive force 𝐹𝑟(𝑡) consists of three main components [18]: 𝐹𝑟(𝑡) = 𝐹drag (𝑡) + 𝐹roll (𝑡) + 𝐹grade (𝑡), …(2) where: 𝐹𝑑𝑟𝑎𝑔(𝑡) = 1 2 𝜌𝐶𝑑𝐴𝑓𝑣 2(𝑡), …(3) 𝐹roll (𝑡) = 𝐶𝑟𝑟𝑚𝑔, …(4) 𝐹grade (𝑡) = 𝑚𝑞sin⁡(𝜃). …(5) 𝐹𝑑𝑟𝑎𝑔(𝑡) is the aerodynamic drag force, 𝜌 is the air density (kg/m3), 𝐶𝑑 is the drag coefficient, and 𝐴𝑓 is the frontal area of the vehicle (m2). 𝐹roll (𝑡) is the rolling resistance force, 𝐶𝑟𝑟 is the rolling resistance coefficient, and 𝑔 is the gravitational acceleration (9.8 ↓1/𝑠 2 ). 𝐹grade (𝑡) is the grade resistance force, and 𝜃 is the road grade angle (radians). 𝑢(𝑡) represents the acc system’s control input, representing the combined throttle and brake commands. 3. proposed control method the nonlinear dynamic model of a vehicle can be transformed into a linear system through feedback linearization, without compromising the accuracy or generality of the system [19]. the control signal is selected as follows (fig. 2): anssam yahya kames al-khwarizmi engineering journal, vol. 21, no.3, pp. 4854 (2025) 50 𝑢(𝑡) = 1 𝛼𝑇 (�̅� + 1 2 𝜌𝐶𝑑𝐴𝑓𝑣 2(𝑡) + 𝐶𝑟𝑟𝑚𝑔 + 𝑘⁡𝑠𝑔𝑛(𝑒)), …(6) where �̅̅� represents an auxiliary controller. the dynamic model of the vehicle system can be expressed as follows: 𝑚 𝑑𝑣(𝑡) 𝑑𝑡 = �̅� + 𝑘⁡𝑠𝑔𝑛(𝑒) + 𝑑, …(7) where 𝑑 = −𝑚𝑔sin⁡(𝜃) can represent the disturbance signal. lyapunov function can be selected as follows: 𝑉 = 1 2 𝑒2, …(8) 𝑒 = �̇�𝑑 − 𝑣, …(9) �̇� = 𝑒�̇� = 𝑒(�̇�𝑑 − �̇�) = 𝑒 (�̇�𝑑 − 1 𝑚 (�̅� + 𝑘⁡𝑠𝑔𝑛(𝑒) + 𝑑)). …(10) if the auxiliary controller �̅� is selected as follows: �̅� = 𝑚�̇�𝑑, ….(11) then, �̇� = 𝑒 (− 𝑘 𝑚 ⁡𝑠𝑔𝑛(𝑒) − 𝑑 𝑚 ) = − 𝑘 𝑚 |𝑒| − 𝑑 𝑚 𝑒, …(12) �̇� ≤ (𝐷 − 𝑘)|𝑒|. …(13) if we select 𝑘 ≥ 𝐷, then �̇� ≤ 0. …(14) thereafter, the final control law will be: 𝑢(𝑡) = 1 𝛼𝑇 (𝑚�̇�𝑑 + 1 2 𝜌𝐶𝑑𝐴𝑓𝑣 2(𝑡) + 𝐶𝑟𝑟𝑚𝑔 + 𝑘⁡𝑠𝑔𝑛(𝑒)). …(15) fig. 2. proposed control method 4. simulation results matlab 2023 was used to simulate the dynamic model of the vehicle system and demonstrate the effectiveness and robustness of the proposed controller in terms of speed control. in addition, the pid controller, tuned using a ga, is simulated to enable a comparison with the proposed controller in terms of transient specification and steady-state error (fig. 3). the ga parameters used for tuning are the values of gains of the pid controller obtained through ga: roulette wheel selection crossover probability=0.7 and mutation rate=0.06. fig. 3. pid tuning 𝐾𝑝 = 1.1, 𝐾𝑖 = 0.002,𝐾𝑑 = −0.51⁡ the gains of the proposed controller are selected as follows: k=10. the vehicle dynamic parameters are listed in table 1: anssam yahya kames al-khwarizmi engineering journal, vol. 21, no.3, pp. 4854 (2025) 51 table 1, parameter values [19] parameter 𝑽𝒂𝒍𝒖𝒆 𝑚 1600kg 𝐶𝑟𝑟 0.01 𝑔 9.8m/𝑠2 𝐶𝑑 0.32 𝜌 1.3kg/m3 𝐴𝑓 2.4m2 𝑣 30m/s 𝑘 10 4.1. reference tracking in this test, a step input was used as a reference speed to compare the performance of the proposed controller with that of the pid controller. the simulation results are shown in figs. 4 and 5. this figure highlights the superior performance of the proposed controller over the pid controller. table 2 lists the transient specifications, including rise time, settling time and overshoot. the proposed controller achieved the shortest rise and settling times with zero overshoot. moreover, the integral absolute error (iae) is used as a performance metric and is be expressed as follows: 𝐼𝐴𝐸 = ∫ |𝑒(𝑡)| 𝑡 0 𝑑𝑡. … (16) the iae values for the two controllers are shown in fig. 5. in particular, the iae values demonstrate the superior performance of the proposed controller compared with the pid controller. fig. 4. step response a ramp function is used in this comparison to evaluate the performance of the controllers against another reference. the simulation results are shown in fig. 6, demonstrating the excellent performance of the proposed controller. fig. 5. iae for step tracking table 2, transient specifications method m_p t_r (sec) t_s (sec) proposed 0 0.2104 0.3751 pid_ga 4.8949 1.3823 3.9354 fig. 6. ramp response 4.2. robustness this study examines the robustness of the proposed controller by applying a disturbance signal lasting 1 s, beginning at 8 s. fig. 7 shows the response of the proposed and pid controllers within a closed loop system. this figure demonstrates the superior robustness of the proposed controller in the presence of external disturbances. moreover, the proposed controller is the least affected by the disturbance and requires only a short duration to return to steady state 0 2 4 6 8 -10 0 10 20 30 40 time(s) s p e e d ( m /s ) ideal position propsed pid 0 2 4 6 8 0 50 100 150 200 time(s) s p e e d ( m /s ) ideal position proposed pid anssam yahya kames al-khwarizmi engineering journal, vol. 21, no.3, pp. 4854 (2025) 52 compared with the pid controller. fig. 8 shows the iae for the two controllers. the proposed controller achieves the lowest iae value, indicating its superior performance. fig. 7. robustness against disturbance fig. 8. iae for external disturbance 5. conclusions this study proposed a robust control method based on smc for the speed control of vehicle dynamic systems. first, a feedback linearization technique is used to transform the nonlinear dynamics of the vehicle system into a linear system. thereafter, lyapunov stability is used to verify the stability of the proposed controller. thereafter, the performance of the proposed controller is compared with that of the pid controller, whose gains are tuned with ga. two cases are discussed to demonstrate the effectiveness of the proposed controller. the first case involves tracking step and ramp reference inputs using the nominal model. meanwhile, the second case evaluates the robustness of the proposed controller by introducing an external disturbance. the simulation results indicate that the proposed controller efficiently performs in tracking step and ramp reference inputs. moreover, the robustness of the proposed controller is evident in the second case, where it rejects external disturbance faster than the pid controller. in future work, the proposed controller can be improved by using reinforcement learning to estimate the dynamic model of the controlled system. references [1] m. levantaci, e. sabbioni, and m. asperti, “modelling and validation of an adaptive cruise control using a high fidelity dynamic driving simulator” tesi di laureamagistrale in mechanical engineering ingegneriameccanica 2021. [2] s. shladover, “connected and automated vehicle systems: introduction and overview,” journal of intelligent transportation systems, vol. 22, pp. 00–00, may 2017, doi: 10.1080/15472450.2017.1336053 [3] d. palac, i. d. scully, r. k. jonas, j. l. campbell, d. young, and d. m. cades, "advanced driver assistance systems (adas): who’s driving what and what’s driving use?," *proceedings of the human factors and ergonomics society annual meeting*, vol. 65, no. 1, pp. 1220–1224, sep. 2021, doi: 10.1177/1071181321651234.. [4] s. k. rao and t. n. kesavamurthy, "a study on advanced driver assistance systems (adas)," *international journal of vehicle structures & systems*, vol. 9, no. 4, pp. 190195, 2017, doi: 10.4273/ijvss.9.4.07. [5] d. wu et al., "multi-objective dynamic coordinated adaptive cruise control for intelligent electric vehicle with sensors fusion," *mechanical systems and signal processing*, vol. 209, p. 111125, mar. 2024, doi: 10.1016/j.ymssp.2024.111125. [6] d. mohammed and b. horváth, “comparative analysis of following distances in different adaptive cruise control systems at steady speeds,” world electric vehicle journal, vol. 15, no. 3, art. no. 3, mar. 2024, doi: 10.3390/wevj15030116. [7] a. h. mary, a. h. miry, and m. h. miry, "design robust h∞-pid controller for a helicopter system using sequential quadratic programming algorithm," *journal of the 0 2 4 6 8 10 -10 0 10 20 30 40 time(s) s p e e d ( m /s ) ideal position propsed pid anssam yahya kames al-khwarizmi engineering journal, vol. 21, no.3, pp. 4854 (2025) 53 chinese institute of engineers*, vol. 45, no. 8, pp. 688-696, 2022. [8] a. ghaffari, n. ghadimi, and b. shokri, "adaptive cruise control with pid and mpc for distance and speed regulation in automated vehicles," ifac-papersonline, vol. 48, no. 3, pp. 64-69, 2015, doi: 10.1016/j.ifacol.2015.06.200. [9] a. musa et al., "a review of model predictive controls applied to advanced driver-assistance systems," *energies*, vol. 14, nov. 2021, doi: 10.3390/en14237974. [10] m. s. ahmed, a. h. mary, and h. h. jasim, "robust computed torque control for uncertain robotic manipulators," *alkhwarizmi engineering journal*, vol. 17, no. 3. pp. 22-28, 2021. [11] w. jiang, w. zhang, and y. zhang, "a fuzzy logic controller for adaptive cruise control system of electric vehicle," proceedings of the ieee international conference on mechatronics and automation, pp. 509-514, 2016, doi: 10.1109/icma.2016.7558592. [12] c. jacobé de naurois, c. bourdin, c. bougard, and j.-l. vercher, “adapting artificial neural networks to a specific driver enhances detection and prediction of drowsiness,” accident analysis & prevention, vol. 121, pp. 118–128, dec. 2018, doi: 10.1016/j.aap.2018.08.017. [13] m. miry, "nonlinear state feedback controller combined with rbf for nonlinear underactuated overhead crane system," *journal of engineering research*, vol. 9, no. 3a, 2021. [14] l. yu and r. wang, "researches on adaptive cruise control system: a state of the art review," journal of automobile engineering, vol. 236, no. 2-3, pp. 211-240, 2022, doi: 10.1177/09544070211019254. [15] p. mahadika, a. subiantoro, and b. kusumoputro, “neural network predictive control approach design for adaptive cruise control,” international journal of technology, vol. 11, p. 1451, dec. 2020, doi: 10.14716/ijtech.v11i7.4592. [16] v. oguntosin and j. olasina, “control design and analysis of cruise control system,” journal of research in engineering and applied sciences, vol. 6, pp. 108–112, jul. 2021, doi: 10.46565/jreas.2021.v06i03.001. [17] v. minh, r. moezzi, j. cýrus, and j. hlava, “model predictive control for autonomous driving vehicles,” electronics, vol. 10, p. 2593, oct. 2021, doi: 10.3390/e [18] r. alika, e. m. mellouli, and e. h. tissir, "a modified sliding mode controller based on fuzzy logic to control the longitudinal dynamics of the autonomous vehicle," *results in engineering*, vol. 22, 2024. [19] k. j. åström and r. m. murray, *feedback systems: an introduction for scientists and engineers*, 2nd ed., princeton, nj: princeton university press, 2010, ch. 6, p. 225. ( 2025) 48-58، صفحة 3، العدد21مجلة الخوارزمي الهندسية المجلد انسام يحيى خميس 54 والتحكم في وضع االنزالق التوجيه المستقل للمركبة على أساس ردود الفعل الخطية انسام يحيى خميس1، علي حسين مري2*، ليث عودة كاظم3، عدي داخل حسن4 2،1 قسم هندسة الميكاترونكس ، كلية الهندسة الخوارزمي، جامعة بغداد، بغداد، العراق 3 جامعة كارلتون، اوتاوا، كندا 4 كلية اسيا الدولية، سيدني، استراليا alimary76@kecbu.uobaghdad.edu.iqالبريد االلكتروني: * المستخلص غذية الراجعة ؛ اقترحت طريقة التحكم القوي في سرعة النظام الديناميكي للمركبات. تجمُع الطريقة المقترحة بين متحكم الوضع المنزلق، وتقنية خطية الت نظام خطي تم فيه استخدام لعدم الخطية العالية للنموذج الديناميكي لنظام السيارة، فيتم استخدام خطية التغذية المرتدة لتحويل النظام الديناميكي للمركبة إلى الجينيةمع الخوارزميات (pid) نظرية اليابونوف للموافقة على استقرار المتحكم المقترح. فضالً عن ذلك، استخدمت وحدة التحكم المشتق التكاملي التناسبي (ga) الخطأ المطلق المتكامل باستخدام (iae) كمؤشر أداء للمقارنة بين أداء وحدات التحكم، فيما تشير نتائج المحاكاة بوضوح إلى أن الطريقة المقدمة . في حالة 15.2هو pid بينما 2.3يمكن أن تحقق أداًء جيدًا بمتانة عالية ضد االضطرابات الخارجية، وعدم اليقين في النظام. فوحدة التحكم المقترحة هي .على التوالي pidلوحدة التحكم المقترحة و 19.1و iae 3.1 االضطراب الخارجي، يكون mailto:alimary76@kecbu.uobaghdad.edu.iq ٤٧ alkhwarizmi engineering journal image restoration using regularized inverse filtering and adaptive threshold wavelet denoising mr. firas ali mechatronics engineering department , alkhwarizmi college of engineering , university of baghdad (received 31 july 2006; accepted 19december 2006) abstract :although the wiener filtering is the optimal tradeoff of inverse filtering and noise smoothing, in the case when the blurring filter is singular, the wiener filtering actually amplify the noise. this suggests that a denoising step is needed to remove the amplified noise .wavelet-based denoising scheme provides a natural technique for this purpose . in this paper a new image restoration scheme is proposed, the scheme contains two separate steps : fourier-domain inverse filtering and wavelet-domain image denoising. the first stage is wiener filtering of the input image , the filtered image is inputted to adaptive threshold wavelet denoising stage . the choice of the threshold estimation is carried out by analyzing the statistical parameters of the wavelet sub band coefficients like standard deviation, arithmetic mean and geometrical mean . the noisy image is first decomposed into many levels to obtain different frequency bands. then soft thresholding method is used to remove the noisy coefficients, by fixing the optimum thresholding value by this method . experimental results on test image by using this method show that this method yields significantly superior image quality and better peak signal to noise ratio (psnr). here, to prove the efficiency of this method in image restoration , we have compared this with various restoration methods like wiener filter alone and inverse filter. key words : image restoration , generalized inverse filter , generalized wiener filter , wavelet transform , denoising using discrete wavelet transform , adaptive threshold wavelet transform, gaussian noise. 1. introduction image restoration are used to improve the appearance of an image by application of a restoration process that uses a mathematical model to remove image degradation . examples of the types of degradation include blurring caused by motion of atmospheric disturbance , geometric distortion alkhwarizmi engineering journal, vol.3, no.1 , pp 48-62 (2007) this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ mr. firas ali/ al-khwarizmi engineering journal, vol.3, no. 1, pp 48-62 (2007) ٤٨ caused by imperfect lenses , superimposed interference patterns caused by mechanical systems , noise from electronic sources , for example in the case of acquiring images with a ccd ( charge coupling device) camera, light levels and sensor temperature are major factors affecting the amount of noise in the resulting image [1],[2]. the degradation process model consists of two parts , the degradation function and the noise function . the general model in the spatial domain follows : where the ** denotes two dimensional convolution process d(x,y) = degraded image h(x,y) = degradation function f(x,y) = original image n(x,y) =additive noise function because convolution in the spatial domain is equivalent to multiplication in the frequency domain , the frequency domain model is where d(u,v) = fourier transform of the degraded image h(u,v) = fourier transform of the degradation function f(u,v) = fourier transform of the original image n(u,v) = fourier transform of the additive noise function in this model, the true image and noise are coupled linearly , therefore, the problem of recovering image from degraded one is referred to as the linear image restoration problem . number of techniques [l], [2] have been proposed in the literature to restore an image from degradations due to blurring and additive noise . inverse filtering ,wiener filtering , parametric wiener filtering , power spectrum filtering , and geometrical mean filtering are some of the examples . the inverse filtering is a restoration technique for deconvolution, i.e., when the image is blurred by a known lowpass filter, it is possible to recover the image by inverse filtering or generalized inverse filtering. however, inverse filtering is very sensitive to additive noise. the wiener filtering executes an optimal tradeoff between inverse filtering and noise smoothing. it removes the additive noise and inverts the blurring simultaneously. so the wiener filtering is optimal in terms of the mean square error because it minimizes the overall mean square error in the process of inverse filtering and noise smoothing. although the wiener filtering is the optimal tradeoff of inverse filtering and noise smoothing , in the case when the blurring filter is singular, the wiener filtering actually amplify the noise. this suggests that a denoising step is needed to remove the amplified noise . image denoising techniques are necessary to remove the random additive noises while retaining as much as possible the important signal features. statistical filters like average filter [1] [2], can be used for removing such noises but the wavelet based denoising techniques proved better results than these filters[3] ,[6] and [7]. in general, image de-noising imposes a compromise between noise reduction and preserving significant image details. to achieve a good performance in this respect, a denoising algorithm has to adapt to image discontinuities. )2(...),(),(),(),( vunvufvuhvud  )1...( ),(),(),(),( yxnyxfyxhyxd  this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ mr. firas ali/ al-khwarizmi engineering journal, vol.3, no. 1, pp 48-62 (2007) ٤٩ the wavelet representation naturally facilitates the construction of such spatially adaptive algorithms. it compresses essential information in a signal into relatively few, large coefficients, which represent image details at different resolution scales. in recent years there has been a fair amount of research on wavelet thresholding and threshold selection for signal and image denoising [3] [4] [6] [7] [8] [10] , because wavelet provides an appropriate basis for separating noisy signal from image signal. many of these wavelet based thresholding techniques have proved better efficiency in image denoising. we consider here an efficient thresholding technique used in [4] for image denoising by analyzing the statistical parameters of the wavelet coefficients. this paper is organized as follows: a brief review of generalized inverse filter for image restoration is provided in section 2. generalized wiener filter equations for image restoration are developed in section 3. image restoration using regularized inverse filtering and wavelet denoising is discussed in section 4. a brief review of discrete wavelet transform (dwt) and wavelet filter banks are provided in section 5. the wavelet based adaptive thresholding technique is explained in section 6. the proposed algorithm steps involved in this work are explained in section 7. in section 8 the experimental results of this proposed work and other restoration techniques are present and compared. finally concluding remarks are given in section 9. 2. image restoration using generalized inverse filter if we know or can create a good model of the blurring function that corrupted an image, the quickest and easiest way to restore that is by inverse filtering. unfortunately, since the inverse filter is a form of high pass filer, inverse filtering responds very badly to any noise that is present in the image because noise tends to be high frequency. in this section , we explore a method of inverse filtering called a thresholding method . we can model a blurred image by where f is the original image, h is some kind of a low pass filter and d is our blurred image. so to get back the original image, we would just have to convolve our blurred function with some kind of a high pass filter r in the ideal case, we would just invert all the elements of h to get a high pass filter. however, notice that a lot of the elements in h have values either at zero or very close to it. inverting these elements would give us either infinities or some extremely high values. in order to avoid these values, we will need to set some sort of a threshold on the inverted element. so instead of making a full inverse out of h, we can an "almost" full inverse by so the higher we set γ , the closer rinv is to the full inverse filter. this is called regularized inverse filter that implemented in our work . 3. image restoration using generalized wiener filter the inverse filtering is a restoration technique for deconvolution. however, inverse filtering is very sensitive to additive noise as explained in the previous section . )5(... ),( 1 ),( 1 ),(       else vuh if vuhvurinv   )4(...),(),(),( yxryxdyxf  )3(...),(),(),( yxfyxhyxd  this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ mr. firas ali/ al-khwarizmi engineering journal, vol.3, no. 1, pp 48-62 (2007) ٥٠ because wiener can removes the additive noise and inverts the blurring simultaneously, it is usually used instead of inverse filter in these cases. the wiener filtering is optimal in terms of the mean square error. in other words, it minimizes the overall mean square error in the process of inverse filtering and noise smoothing. the approach is based on a stochastic framework. the wiener filter in fourier domain can be expressed as follows: )6(... ),(),(),( ),(),( ),( 2 vusvusvuh vusvuh vur nim im w    where sim , sn are respectively power spectra of the original image and the additive noise, and h(u,v) is the blurring filter. it is easy to see that the wiener filter has two separate part, an inverse filtering part and a noise smoothing part. it not only performs the deconvolution by inverse filtering (high pass filtering) but also removes the noise with a compression operation (low pass filtering). to implement the wiener filter in practice we have to estimate the power spectra of the original image and the additive noise. for white additive noise the power spectrum is equal to the variance of the noise. to estimate the power spectrum of the original image many methods can be used. a direct estimate is the periodogram estimate of the power spectrum computed from the observation:   )7(...),(),( 1 2  vudvud n s per yy where d(u,v) is the dft of the observation. the advantage of the estimate is that it can be implemented very easily without worrying about the singularity of the inverse filtering. another estimate which leads to a cascade implementation of the inverse filtering and the noise smoothing is )8(... 2 h ss s nyy im   which is a straightforward result of the fact : 2 hsss imnyy  the power spectrum syy can be estimated directly from the observation using the periodogram estimate. this estimate results in a cascade implementation of inverse filtering and noise smoothing: )9(... 1 ),( per yy n per yy w s ss h vur   4. image restoration using regularized inverse filtering and wavelet denoising although the wiener filtering is the optimal tradeoff of inverse filtering and noise smoothing, in the case when the blurring filter is singular, the wiener filtering actually amplify the noise. this suggests that a denoising step is needed to remove the amplified noise. wavelet-based denoising scheme, a successful approach provides a natural technique for this purpose. therefore, the image restoration contains two separate steps: fourier-domain inverse filtering and wavelet-domain image denoising. the diagram is shown as follows. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ mr. firas ali/ al-khwarizmi engineering journal, vol.3, no. 1, pp 48-62 (2007) ٥١ the approach that shown in fig.(1) for image restoration improves the performance, however, in the case when the blurring function is not invertible, the method is not applicable. furthermore, since the two steps are separate, there is no control over the overall performance of the restoration. so a wavelet-based deconvolution technique for illconditioned systems can be proposed. the idea is simple: employ both fourier-domain wiener-like and wavelet-domain regularization. the regularized inverse filter is introduced by modifying the wiener filter given in equation (6) with a new-introduced parameter α : )10(... 2 nim im ssh sh g      the parameter α can be optimally selected to minimize the overall meansquare error. the diagram of the algorithm is displayed as follows:. 5. discrete wavelet transform the dwt is identical to a hierarchical subband system where the subbands are logarithmically spaced in frequency and represent octave-band decomposition. due to the decomposition of an image using the dwt [1] the original image is transformed into four pieces which is normally labeled as ll, lh, hl and hh as in the schematic depicted in fig. (3 a.). the ll subband can be further decomposed into four subbands labeled as ll2, lh2, hl2 and hh2 as shown in fig.3 b. inverse filtering wavelet denoising ),( yxd ),(ˆ yxf ),( ~ yxf fig.(1) block diagram of image restoration using inverse filtering and wavelet denoising regularized inverse gα wavelet denoising ),( yxd ),(ˆ yxf ),( ~ yxf fig.(2) block diagram of image restoration using regularized inverse filtering and wavelet denoising this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ mr. firas ali/ al-khwarizmi engineering journal, vol.3, no. 1, pp 48-62 (2007) ٥٢ the ll piece comes from low pass filtering in both directions and it is the most like original picture and so is called the approximation. the remaining pieces are called detailed components. the hl comes from low pass filtering in the vertical direction and high pass filtering in the horizontal direction and so has the label hl. the visible detail in the sub-image, such as edges, have an overall vertical orientation since their alignment is perpendicular to the direction, of the high pass filtering and they are called vertical details. the remaining components have analogous explanations. the filters ld and hd shown in fig. 4 are one-dimensional low pass filter (lpf) and high pass filter (hpf) respectively for image decomposition. to obtain the next level of decomposition, sub band ll1 alone is further decomposed. this process continues until some final ll1 hl1 lh1 hh1 hl1 lh1 hh1 ll2 hl2 lh2 hh2 (a) one-level (b) two -level fig. 3 image decomposition by using dwt this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ mr. firas ali/ al-khwarizmi engineering journal, vol.3, no. 1, pp 48-62 (2007) ٥٣ scale is reached. the decomposed image can be reconstructed using a reconstruction filter as shown in fig. 5. here, the filters lr and hr represent low pass and high pass reconstruction filters respectively. here, since the image size is not changed after decomposition this dwt is called critically sampled transform without having any redundancy. 6. wavelet thresholding let f={fij,i,j=1,2,....m} denotes a m x m matrix of original image to be recovered and m is some integer power of 2. during the transmission, the signal f is corrupted by independent and identically distributed (i.i.d) zero mean, white gaussian noise nij with standard deviation σ ,and at the receiver end, the noisy observation dij=fij+nij is obtained. the goal is to estimate the signal f from the noisy observations dij such that the mean square error (mse) is minimum. to achieve this the dij is transformed into wavelet domain, which decomposes the dij into many subbands as explained in section 5, which separates the signal into so many frequency bands. the small coefficients in the ld hd 2 ٢ hd ld ld hd ٢ ٢ ٢ ٢ row s ll lh hl hh f(x,y) input image l l lh hl hh ٢ ٢ ٢ ٢ lr h r h r lr ٢ ٢ lr h r colum ns row s f(x,y) fig.4 wavelet filter bank for one-level image decomposition fig.5 wavelet filter bank for one-level image reconstruction columns this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ mr. firas ali/ al-khwarizmi engineering journal, vol.3, no. 1, pp 48-62 (2007) ٥٤ subbands are dominated by noise, while coefficients with large absolute value carry more signal information than noise. replacing noisy coefficients (small coefficients below certain value) by zero and an inverse wavelet transform may lead to reconstruction that has lesser noise. normally hard thresholding and soft thresholding techniques are used for such denoising process. hard and soft thresholding [4] with threshold λ are defined as follows: the hard thresholding operator is defined as )11(... 0 ),(      otherwise uallforu ud   the soft thresholding operator on the other hand is defined as hard thresholding is “keep or kill” procedure and is more intuitively appealing and also it introduces artifacts in the recovered images. soft thresholding , on the other hand , have proved to be more efficient and it is used for the entire algorithm for the following reasons : soft thresholding has been shown to achieve near minmax rate [3],[4] and [8]. moreover, it is also found to yield visually more pleasing images. the above factors motivate us to use this soft thresholding in our denoising method. 6.1. estimation of parameters for threshold value finding an optimum threshold value (λ) for soft thresholding is not an easy task. a small threshold value will pass all the noisy coefficients and hence the resultant denoised signal may still be noisy. a large threshold value on the other hand, makes more number of coefficients as zero which leads to smooth signal and destroys details and may cause blur and artifacts. so, optimum threshold value should be found out, which is adaptive to different subband characteristics. here, we describe an efficient method for fixing the threshold value for denoising by analyzing the statistical parameters of the wavelet coefficients. the threshold value (λ) that used for soft thresholding technique is given by: λ = c σ −( am − gm ) …(13) where σ is the noise variance of the corrupted image , am and gm are the abbreviates for arithmetic mean and geometric mean of the subband coefficients respectively and the term c is included to make the threshold value depend on decomposition level. in some applications of image denoising, the value of the input noise variance is known, or can be measured based on the information other than the corrupted data. if this is not the case, one has to estimate it from the input data. for this, wavelet based method commonly used the highest frequency subband of the decomposition. in the dwt of the image, the hh1 subband contains mainly noise. for estimating the noise level we use the relation used in [3],[4] and [8] , which is denoted as )14(... , 6745.0 ][ 1hhsubbandy ymedian ij ij  normally in wavelet subbands, as the level increases the coefficients of the subband becomes smoother. for example the subband hl2 is smoother than the corresponding subband in the first level (hl1) and so the threshold value of hl2 should be smaller than that for hl1. so , the term c is included for this purpose to make the threshold value as decomposition level dependent and is given by, )12(... ),0max(*)sgn(),(   uuud )15(...2 )( klc  this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ mr. firas ali/ al-khwarizmi engineering journal, vol.3, no. 1, pp 48-62 (2007) ٥٥ where, l is the no. of wavelet decomposition level k is the level at which the subband is available (for hl2, k=2). the term |am gm| is the absolute value of difference between arithmetic mean and geometric mean of the subband coefficients. this term is the measure of the smoothness of the image to be denoised. if an image is having more edges, then the noisy wavelet coefficients of the image should be removed by fixing slightly lower threshold value so as to keep the image edges undisturbed. this can be achieved by this term, since small value of this term indicates that the subband is having smooth edges and vice versa. this term makes the threshold value as image dependent and helps to preserve the image edges to some extent, which results in better image quality. the arithmetic mean and geometric mean of the subband matrix x(i,j) are denoted as, thus each term in equation (13) has its’ own importance as explained above to make the threshold value more adaptive to subband coefficients as well as level of decomposition. 7. image restoration algorithm the complete algorithm of proposed wiener wavelet based restoration technique is explained in the following steps : 1. restore the degraded image without denoising using the regularized inverse filter with α = 1. 2. perform the dwt of the restored noisy image coming from step 1 up to 2 levels (l=2)to obtain seven subbands which are named as hh1, lh1,hl1, hh2, lh2, hl2 and ll2. 3. compute the threshold value for each subband, except thell2 band using equation (13) , after finding out its following terms. (i) obtain the noise variance using the equation (14). (ii) find the term c for each subband using the relation given in equation (15). (iii) calculate the term |am-gm| using the equations (16) and (17). 5. threshold the all subband coefficients (except ll2) using soft thresholding technique given in equation (12), by substituting the threshold value obtained in the step 3. 6. perform the inverse dwt to reconstruct the degraded image. 8. experimental results and discussion a test image zoza of size 256x 256 is blurred by 4x4 average low pass filter have a coefficients values of 1/16 , then the proposed algorithm has been applied on different added gaussian noise of levels: (standard deviation) σ = 1 to 100 . we used ‘daubechies’ (db4)[13] at two levels of decomposition. to evaluate the performance of the proposed method, it is compared with inverse filter , and wiener filter alone without denoising step using peak signal to noise ratio (psnr) [4], which is defined as : where, mse denotes the mean square error between the original and the restored images, and is given as: )16(... 1 1 ),( 2 1 )(      m i m j jix m ammeanarithmetic )17...( 2 1 1 1 ),()( mm i m j jixgmmeangeometric            )18...( )),(),(( log10 2 minmax 10         mse yxdyxd psnr this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ mr. firas ali/ al-khwarizmi engineering journal, vol.3, no. 1, pp 48-62 (2007) ٥٦ )19(... )),( ~ ),(( 1 1 1 2    m i n j jifjif mn mse where, m width of image n height of image f ~ (i,j) restored image or processed image f (i,j) original image figure(6) shows the psnr against white gaussian noise standard deviation for three filters , inverse filter , wiener filter alone and our proposed method the involve additional denoising method after wiener filter. it is obvious from fig.(6) that our proposed method outperforms the inverse and the wiener filters . it removes noise significantly and hence restore the image better than traditional wiener filter. fig. (7) shows the original zoza image , the degraded image for sigma = 25 , 50 and 75 and resulting images of inverse filter , wiener filter, and proposed method of zoza image. it is clear that the proposed method outperforms the other methods in visual perception especially in high noise level. (a) zoza image fig.( 6 ) comparison chart of psnr for different methods 0 5 10 15 20 25 30 35 40 1 11 21 31 41 51 61 71 81 91 standard deviation of gaussian noise p s n r in d b adaptive thershold wavelet generlized wiener generlized inverse this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ mr. firas ali/ al-khwarizmi engineering journal, vol.3, no. 1, pp 48-62 (2007) ٥٧ (b) degraded image with sigma = 25 (c) resorted image using inverse filtering (d) resorted image using wiener filtering (e) resorted image using our proposed method this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ mr. firas ali/ al-khwarizmi engineering journal, vol.3, no. 1, pp 48-62 (2007) ٥٨ (f) degraded image with sigma = 50 (g) resorted image using inverse filtering (h) resorted image using wiener filtering (i) resorted image using our proposed method this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ mr. firas ali/ al-khwarizmi engineering journal, vol.3, no. 1, pp 48-62 (2007) ٥٩ (j) degraded image with sigma = 75 (k) resorted image using inverse filtering (l) resorted image using wiener filtering (m) resorted image using our proposed method fig.(7) restoration of ‘zoza’ image blurred by 4x4 average filter and corrupted by gaussian noise of standard deviation of 25 , 50 and 75 using different methods this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ mr. firas ali/ al-khwarizmi engineering journal, vol.3, no. 1, pp 48-62 (2007) ٦٠ 9. conclusion a method for image restoration have been proposed here. the proposed method added to wiener filter a denoising step to remove the amplified noise. wavelet-based denoising scheme with adaptive threshold is the denoising step that used in our work. experiments are conducted on image corrupted by various noise levels to access the performance of thresholding method in comparison with filters like wiener and inverse filters. the obtained experimental results proved that our proposed method better than inverse and wiener filters because it is removed noise significantly and restored the image better than the other methods , and this is very clear in visual perception of results especially in high noise level . from the results , its clear that our proposed restoration technique has possessed better psnr than inverse and than traditional wiener filter and this is because of the additional noise removal step, and because this denoising step is more subband adaptive and is based on the analysis of statistical parameters like arithmetic mean, geometrical mean and standard deviation of the subband coefficients, so at higher values of sigma our proposed method overcame the other two methods. the method also overcame the wiener filtering in the case when the blurring filter is singular where wiener filtering actually amplified the noise.on the other hand, and at high values of sigma, some artifacts have been added to the restored image due to wavelet denoising, and this can be left for future work to suggest a suitable additional filter or method to remove these artifacts. finally, and from applications point of view, since the proposed method proved to have better psnr than other methods , it can be used in restoration applications where the images are degraded during transmission , which adds random noise normally in nature. references:[1] rafael c.gonzalez & richard e.wodds, “digital image processing”, prentice-hall, inc., 2002. [2] scott e umbang., "computer vision and image processing", a practical approach using cvip tools, prentice hall, inc., upper saddle river, 1998. [3] lakhwinder kaur , savita gupta , r.c. chauhan , "image denoising using wavelet thresholding", dept. of cse sliet, longowal punjab (148106), india, e-mail: mahal2k8@yahoo.com, savita2k8,@yahoo.com, rcchauhan@hotmail.com [4] d.gnanadurai, and v.sadasivam, “an efficient adaptive thresholding technique for wavelet based image denoising", international journal of signal processing volume 2 number 2 2005 issn 1304-4494. [5] zeljko devcic sven loncaric “blur identification using averaged spectra of degraded image singular vectors “, institute for defence studies, research and development, university of zagreb, bijenicka 46, 10000 zagreb, croatia, e-mail: zdevcic@zvonimir.morh.tel.hr [6] byung-jun yoon and p. p. vaidyanathan, " wavelet-based denoising by customized thresholding", dept. of electrical engineering california institute of this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ mr. firas ali/ al-khwarizmi engineering journal, vol.3, no. 1, pp 48-62 (2007) ٦١ technology, pasadena, ca 91125, usa, e-mail: bjyoon@caltech.edu, ppvnath@systems.caltech.edu [7] xiaoyan xu, “image denoising in wavelet domain”, school of engineering, university of guelph, e-mail: xux@uoguelph. [8] carl taswell , " experiments in wavelet shrinkage denoising " c. taswell (ctaswell@toolsmiths.com) , computational toolsmiths , pob 18925, stanford, ca 94309-8925. [9] yi wan and robert d. nowak ," wavelet-based statistical model for image restoration " , rice university , department of electrical engineering, 6100 south main street, houston, tx 77005, usa. [10] javier portilla and eero p. simoncelli ," image denoising via adjustment of wavelete coefficient magnitude correlation", center for neural science, and courant institute of mathematical sciences new york university, ny 10003, e-mail: fjavier,eerog@cns.nyu.edu. [11] jae s. lim, " image restoration by short space spectral subtraction”, ieee transactions on acoustics, speech, and signal processing, vol. assp-28, no. 2, april, 1980. [12] a. buades, b. coll, and j. m. morel, “a review of image denoising algorithms with a new one”, multiscale model. simul. 2005 society for industrial and applied mathematics, vol. 4, no. 2, pp. 490– 530. [13] matlab help, version 7. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ mr. firas ali/ al-khwarizmi engineering journal, vol.3, no. 1, pp 48-62 (2007) ٦٢ رشیح المنظم المعكوس و إزالة الضوضاء بطریقة استعادة الصور باستخدام الت التحویل المویجي ذو العتبة العتبة المتكیفة فراس علي جواد كلیة ھندسة المیكاترونیكس/ قسم ھندسة المیكاترونیكس جامعة بغداد :الخالصة شح یعتبر مرشح وینر كحل مثالي بین الترشیح المعكوس وأزالھ الضوضاء لكن في حالة كون مر التشویھ منفرد سیؤدي مرشح الوینر الى تضخیم الضوضاء لذلك یجب إضافة خطوة بعد الوینر إلزالة الضوضاء .لھذا الغرض" سیكون نظام ازالة الضوضاء المبني على تحویالت المویجة مفضال. مجال معكوس الترشیح في : في ھذا البحث تم اقتراح نظام استعادة الصورة یتضمن خطوتین منفصلتین , المرحلة االولى ھي ترشیح وینر للصورة الداخلة . فوریر وازالة الضوضاء باستخدام التحویل المویجي اختیار . الصورة المرشحة یتم ادخالھا الى مرحلة ازالة الضوضاء بطریقة التحویل المویجي ذات العتبة المتكیفة تخمین العتبة یتم عن طریق تحلیل العوامل االحصائیة لمعامالت نصف الحزمة المویجیة والتي ھي االنحراف الصورة المشوشة تجزأ الى مستویات عدة للحصول على عدة . المعدل الحسابي والمعدل الھندسي , المعیاري وضاء عن طریق تثبیت قیمة العتبة المثلى بھذه ثم یتم استخدام طریقة العتبة الناعمة الزالة الض. حزم ترددیة . الطریقة النتائج التجریبیة على صورة اختبار بأستخدام ھذه الطریقة تبین انھ ھذه الطریقة تؤدي الى الحصول على نوعیة تؤدي الى الحصول على قمة نسبة اشارة الى " صور افضل مقارنة مع مرشحات وینر ومرشح المعكوس وایضا .ضل من باقي الطرق ضوضاء اف this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ <4d6963726f736f667420576f7264202d2038392d203939e3cde3e6cf20e6c7e3edd120cccfe6da> al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 15, no. 2, june , (2019) p.p. 8999 effect of using air guide net in front of the condenser on the performance of automobile air conditioning system mahmoud maustafa mahdi* a. a. gaddoa** *,**department of electromechanical engineering/ university of technology/ baghdad/ iraq *email: mahmoud_mahdi74@yahoo.com **email: en_ameerabed@yahoo.com (received 5 september 2018; accepted 19 february 2019) https://doi.org/10.22153/kej.2019.02.001 abstract the work of this paper is an investigation to improve the condenser performance of the automobile air conditioning system by enhancing the air-side heat transfer from the condenser through the use of an air guide net installed in front of the condenser face which is basically an aluminum plate having a circular entrance shape for the air passage. the a/c system was examined under two types of test. the first test was conducted the air guide net, while the second was done with the air guide net. the performances of the a/c system under these tests were compared. for the second type of test, the experiment was carried out with three different size of air guide net, three different circular diameters (2, 3 and 3.5 cm) and a common air passage area. the effect of varying the size of the air guide net and its inclination angle was investigated. the experimental work included five inclination angles (0o, 5o, 10o, 15o and 20o). it was found that the presence of the air guide net caused an improvement in the performance of the a/c system for all sizes and inclination angles. in addition, the electrical energy consumed by the a/c system without the air guide net was calculated and compared to those obtained for the a/c system with the air guide net. the results manifested that the reduction of the power consumption was enhanced by operating the a/c system with the air guide net. keywords: automobile a/c system, coefficient of performance, air guide net, experimental investigation. 1. introduction refrigeration systems are widely used in commercial buildings, offices, airport, and hospital and in automobiles. automobile air conditioning system is the biggest auxiliary load on the vehicle engine (internal combustion engine cars). it consumes a large amount of energy up to 30% of the fuel. alison, et al. [1]. fortunately, there are various ways to improve the coefficient of the performance of the a/c system, such as enhancement the performance of the condenser component. in order to enhance the performance of the condenser, it is important to enhance the air side heat transfer which is the dominant one. automotive a/c system is mainly consisting of a condenser, a compressor, an expansion value and an evaporator. some significant characteristics that effect on the performance of the automotive a/c system more are complicated than the other a/c systems, bhatti [2]; and kiatsiriroat, and euakit. [3]. the actual performance of the automotive air conditioning system is a result of the balancing among the essential cycle components when the performance of any above components of the air-conditioning system varies as a result of one or more effecting factors, and this will reflect on the performance of the other component of the a/c system. one of the effecting factors on the performance of the condenser component is the air side heat transfer coefficient. when the air side heat transfer coefficient varies, it affects the performance of the condenser, which in turn affects the performance of the other components of the a/c system. mahmoud maustafa mahdi al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 8999 (2019) 90 jabordo et al. [4] analyzed an automotive a/c system, focusing on the relation between the c.o.p and compressor capacity. schwarz et al. [5] experimentally determine the flow inside the accumulator of the a/c system of an automotive. they found that the flow inside the accumulator is critical to the coefficient of performance of the a/c system, lubrication and safety for the compressor. awaji et al. [6] studied the two-phase flow inside the evaporator of a/c system and found the effect of the flow on the heat transfer performance of the evaporator component. joudi et al. [7] noticed that the experimental analysis is an effective method for analyzing the automotive a/c system. shu, and hany [8] analyzed the split of residential water-cooled air conditioning system. they determined that the water used in cooling the condenser resulted in decreasing in the energy consumption of the compressor from 1.189 to 1.02 kw and an increasing in the c.o.p of the a/c system from 2.96 to 3.45. yu, and chan [9] improved the c.o.p. of an air-cooled chiller by using variable speed condenser fan to modulate the heat rejection air flow. they presented a program to determine the number and the speed of the fans used to cool the condenser and to provide the required air flow for a given condenser heat rejection. jiang et al. [10] showed how the condensing recovery affects the cooling and the average c.o.p of a/c system. amarnath [11] investigated the effect of condenser heat exchanger on the c.o.p of the a/c system. he found that increasing the condenser area will ensure more heat transfer to the surroundings from the condenser component of a/c system, which increases sub cooling. aby et al. [12] experimentally investigated the various types of condenser on the performance of vapor compression cooling system in order to reduce the energy consumption of the system. in addition, they studied the effect of many parameters, such as the air flow rate and the condenser heat transfer coefficient on the c.o.p. of the system. it was found that the evaporative condenser enhanced the process of condenser heat rejection and therefor improved the reduction of energy consumption. improving the performance of the condenser component of an a/c system can be achieved by multiple techniques. the enhancement of condensation heat transfer coefficient has been investigated by many authors, including choui [13], coleman and s. gaarimella [14] and bari et al. [15]. varma, and gupta [16] determined the effectiveness of an air conditioning condenser and noticed that in some applications, the air flow nonuniformity affects the thermal performance of the condenser component. a wad et al. [17] investigated the effect of inclination angle of flat tubes condenser on the convection air side heat transfer coefficient. they found an optimum angle of 4o, which offered the best enhancement in the air side heat transfer performance. song et al. [18] numerically and experimentally investigated the impact of non-uniform air velocity distribution on the performance of the evaporator. they found that the capacity of the evaporator under uniform air velocity distribution was 7.78% higher than that under non-uniform velocity distribution. zhaoying, and jianguo y. [19] determined the effect of face-air velocity distribution on the thermal performance of an air-cooled condenser of a power plant. they noticed that the distribution of the air velocity affects the thermal performance of the air cooled condenser. as shown in the literature survey on the performance of the condenser component of a/c system, it revealed that increasing the condenser heat rejection leads to the improvement of the refrigeration cycle performance system. furthermore, in summary, the literature on guiding the cooling air flowing depicted that the guiding devices can make a better air flow uniformly and improve the heat transfer performance of an air cooled condenser of a/c system. therefore, the objective of this study is to: 1. investigate the impact of using an air guide net in front of the condenser component on the performance of an air-cooled automobile training unit. 2. evaluate the performance of automobile a/c system under different air guide net sizes and inclination angles and ultimately identify the optimum inclination angle of the air guide net corresponding to a better c.o.p of the system. 2. methodology the automobile a/c system is vapor compression refrigeration cycle. the vapor compression cycle is basically a system, which consists of an evaporator, a compressor, a condenser and an expansion device. figure (1a) shows a typical schematic representation of the vapor compression refrigeration cycle. the cycle can be divided down into the following stage, as shown in figure (1b). mahmoud maustafa mahdi al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 8999 (2019) 91 stage 1-2 compressor: the energy equation, which represents the amount of the specific work done by the compressor, is: wcompressor.s = (h2s -h 1) … (1) where: h1= the enthalpy of working refrigerant entering the compressor. h2s = the enthalpy of the working refrigerant that exits from an isentropic compressor. the actual specific work required from a non isentropic compressor is depending the efficiency: wcompressor.a= wcompressor.s / ηcompressor … (2) where: ηcompressor.a = the thermal efficiency of the compressor. the volumetric efficiency can be defined as the ratio of the vapor mass that is compressed to the vapor mass that compressed ideally. the volumetric efficiency of compressor is: ηv = 1rp,c [( υ1 /υ2 ) -1 ] …(3) where: ηv = the volumetric efficiency of the compressor. rp,c = ratio (piston / cylinder) of clearance volume to the swept displacement. υ1 = the entering specific volume to the compressor. υ2 = the existing specific volume from the compressor. the volumetric efficiency can be used to determine the mass flow rate of the refrigerant that enters and exits from the compressor. m• = (ηv × pd) /υ2 … (4) where: pd = the displacement of the piston. stage 2-3 condenser: the heat rejected in the condenser from the refrigerant (working fluid) to the air side at the outside condenser face is: q condenser = h2 – h2a … (5) stage 3-4 expansion device: across the expansion valve the equation of energy shows that the enthalpy is maintained constant. h3 = h4 … (6) stage 4-1 evaporator: the specific heat absorbed can be determined by the refrigerant enthalpies at the inlet and outlet of the evaporator. qevaporator = (h4–h1) … (7) the overall performance of the cycle system can be evaluated by the coefficient of performance (c.o.p). c.o.p = qevaporator / wp … (8) where: wp = the electric energy required by the cycle system. fig. 1a. schematic of the vapor compression refrigeration cycle. fig. 1 b. refrigeration air conditioning system 3. experimental apparatus and test procedure an automobile a/c training system, (3 kw) cooling capacity, using (hfc-r134a), was selected for the tests. the a/c system contains the basic components corresponding to the vapor compression system: an evaporator, a condenser, a compressor and an expansion device and such attachments self-closing valve: schrader type, a dehydrating filter and a pressure switch (trinity type). figure (2) displays the schematic illustration of the experimental setup used in this investigation. mahmoud maustafa mahdi al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 8999 (2019) 92 fig. 2. instruments of automobile air conditioner training unit: 1-air guide net, 2condenser, 3condenser fan, 4-low pressure manometer,5compressor, 6-high pressure manometer, 7-indoor temperature display, 8-electrical resistance (human body heat simulator, 9-low pressure switch, 10control board, 11-evaporator, 12-outdoor temperature display, 13-therostatic expansion valve, 14-low pressure switch, 15-filter drier. the air-cooled condenser stands with a cooling capacity of 4.5 kw. the condenser undergoes cooling through a forced convection by the condenser fan, which was employed to extract the room air through the condenser component and discharge it outside the a/c system unit, as shown in figure (3). fig. 3. an automobile a/c training system. the evaporator was insulated so that the heater power input can be considered as the cooling capacity (or human body heat simulator). a thermostatic expansion valve was used as an expansion device to change the sub-cooled liquid (with higher pressure) into vapor-liquid mixture (with lower pressure). a measurement system and controls were set-up to conduct the data processing and to control the a/c system operation. the temperature (or the condition) of the air at the front of the condenser face was measured by a digital temperatures humidity meter. figure (4) manifests the front view of the two different condenser configurations, namely without an air guide net and with air guide net. (a) (b) fig. 4. front view of the two different condensers, (a) without guide net and (b) with air guide net. an air guide net is basically a plate with circular holes drilled in order to allow the air pass through it before passing the face of the condenser, used and placed in front of the condenser face, in order to change the air velocity distribution upstream the condenser face and hence to find its effect on the performance on the a/c system, as shown in figure (4). the air guide net was made of 1 mm aluminum plate. the plate was drilled to provide the necessary access for the air passing through it, so, the plate contained holes. three different air guide nets having different hole radius (1, 1.5 and 1.75 cm) were tested. the system power consumption was measured by a digital wattmeter. by this system, the pressure, temperature and power were measured. all the measured data were processed to calculate other parameters. also, this system can operate the a/c system under controlling, such as turning the power off or on and adjusting the speed of the compressor. experiments were mahmoud maustafa mahdi al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 8999 (2019) 93 carried out on the automobile a/c system with and without an air guide net. the system was tested under the same conditions. initially, the apparatus was switched on. full air flow rate was adjusted by the condenser fan. the temperature of the air, which cooled the condenser, is kept constant at 38 oc during these experiments. approximately 30 min were required to reach the steady state. after the steady state condition, the average values of each experimental variable (temperature, pressure and power consumption) were collected. after the collection of all data for the (case without air guide net) performed, the air guide net was put in front of the condenser face so that a new experimental configuration was tested. table (1) lists the geometrical dimensions of the air guide net samples. the same procedure was repeated for each of various experimental air guide net sizes. for each air guide net size of the second group, the inclination angle of the air guide net was varied to determine the effect of inclination angle on the performance of the a/c system and to obtain the better inclination angle that gives a maximum c.o.p of the a/c system. table (2) reveals a brief outline of the experimental program. table 1, geometric dimensions of the air guide net. table 2, a brief outline of the experimental program. 4. results and discussion through these practical experiments, the nature and shape of the airway passing through the face of the condenser surface have been changed using a variety of air guide net sizes before the air enters the condenser. to illustrate the effect of placing these air guide nets in front of the surface of the condenser and to show the improved increasing of the heat rejection from the condenser, a comparison was made between the two cases (without and with using air guide net). the effect of the air guide net size (i.e. the hole size diameter) on the performance of a/c system was investigated for the system of the second group. for the second group, experiments were carried out at three different air guide net sizes. in addition, based on the experimental results, of the second group, the performance of the a/c system when changing the inclination angle of the air guide net was evaluated. the effect of various operating factors on the performance of the a/c system will be discussed in the following sections. the parameters that affect the a/c system performance were considered for illustration. several parameters were measured, charted and discussed, such as discharge temperature (working fluid inlet temperature to the condenser), c.o.p of the a//c system and system power consumption. 4.1 the effect of air guide net on the discharge temperature (td) figure (5) elucidates the comparison between a/c system without and with an air guide net for three different air guide net sizes. the effect of various air guide sizes on the discharge temperature is displayed in this figure at an inclination angle of (0o). it is clearly shown that the discharge temperature is on a higher side in the case without air guide net and low in the case with air guide net. the discharge temperature was observed between (68.1o c to 64.2 oc) in the case with air guide net. also, the discharge temperature changing with the air guide net size by ( 5oc) for sample (1), (8.9 oc) for sample (2) and (6.2 oc) for sample (3) in comparing with the case without air guide net sample air guide net dimension (cm) air guide net size hole radius (cm) air side passage area (cm2) no. of holes face condenser area blocked (%) 1 33×33 1 546.6 174 50.19% 2 33×33 1.5 544.2 77 50% 3 33×33 1.75 548 57 50.3% type of testing the a/c system air guide net size hole radius (cm) inclination angle (degree) testing the a/c system without an air guide net first group ------------ testing the a/c system with an air guide net second group 1 0o,5o,10o,15o,20o 1.5 0o,5o,10o,15o,20o 1.75 0o,5o,10o,15o,20o mahmoud maustafa mahdi al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 8999 (2019) 94 air guide net , that in mean the reduction in the discharge is about (6.8 %) for the air guide net sample (1), and about (12%) for the air guide net sample (2), while at air guide net sample (3), the reduction is about (8.6 %) in comparison with the case without air guide net. the reduction in the discharge temperature can be attributed to the fact that the decreasing in the face area of the condenser leads to increasing the velocity of the air over the other part of the condenser by a higher percentage; i.e. when the face condenser area is reduced by (50%), the velocity of the air across the rest of the condenser increases. this means increasing the air velocity is working against the loss in face area, i.e. offsetting completely the effect of the reduction in the condenser face area. as a result, the heat transfer coefficient of the air side increases by a higher percentage, because the air heat transfer coefficient is dependent on the reynolds number (and thus velocity), also, the tubes and fins area ate free to conduct the heat to the condenser area, which is still exposed to the flow of the air. furthermore, the (50%) of the condenser area is still has free convection over it. in addition to that, the air with a higher velocity will still moving next to the fins to a certain extent because of the sudden expansion and contraction that the air flow gives behind the condenser and the forced convection will enhance the thermal heat transfer to a certain extent. the enhancement of the air side heat transfer coefficient is important in the two-phase region of the condenser, where more than (80%) is air side resistance of the total resistance choui [13]. that means the enhancement of the overall heat transfer coefficient of the condenser will occur. this enhancement (for the case with air guide net) makes the condenser need only a less two-phase area, hence, the percentage area of the two-phase region has increased. this makes the superheated transient point slowly move down stream (i.e. reducing the discharge temperature of the working fluid (r134a). the movement of the superheated region causes a greater percentage of the condenser size to be two-phase replacing the superheated region. fig. 5. comparison of discharge temperature (td) between with and without air guide net. 4.2 the effect of air guide net on the cycle c.o.p. it was pointed out in the previous section that, by installing an air guide net upstream the condenser, the working fluid discharge temperature (r134a) decreases as a result of increasing the two-phase region of the condenser which makes the superheated transition point move down stream. figure (6), evinces the variation of calculated cycle c.o.p of different air guide net samples. this figure also shows the comparison of the c.o.p of the a/c system for the three air guide net sizes (three samples) with that of no air guide net. the cycle c.o.p of the a/c system is observed to be higher with air guide net. the air guide net size of sample (2) appears to give the best result in term of c.o.p in comparison with the other air guide net sizes (sample 1 and sample 3). it’s observed from figure (6) that the minimum c.o.p (2.21) is reached in the case of without using of air guide net and maximum c.o.p (2.65) in the case of using an air guide of sample (2). these results can be attributed to two reasons. first, the objective of the air guide net is to direct the air stream in a direction perpendicular to the condenser face plane and when the air streams strike the face of the condenser, a large amount of heat dissipation from the condenser would be transferred to the air passing through the condenser. the second, the reduction of discharge temperature (td) reduces the specific volume of the cycle working fluid (r134a) and thus increases the volumetric efficiency of the compressor in equation (3) which mahmoud maustafa mahdi al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 8999 (2019) 95 reduces the energy spent in the compressor. the reduction of energy spent in the compressor and with the same heat capacity at the evaporator lead to an improvement in the cycle c.o.p of the a/c system equation (8). fig. 6. graphical representation of cycle c.o.p for the a/c system with and without air guide net. figure (7) demonstrates the representation of the percentage increase of c.o.p for three different air guide net sizes. it can be seen from this figure that, the c.o.p increased by (13%) for the case with an air guide net (sample 1) in comparison with the case without air guide net, while for the air guide net (sample 2), the increasing is about (17%), also for the air guide net (sample 3), the increasing is about (14 %). fig. 7. graphical representation of cycle c.o.p percentage increasing for the a/c. 4.3 the effect of inclination angle based on the experimental results, the performance of the a/c system when changing the inclination angle of the air guide net was evaluated. different cycle c.o.p values under three different air guide net sizes (three samples) and five inclination angle are shown in figure (8). in this figure, a typical variation of the cycle c.o.p with inclination angle from (0o to 20o) is shown. as shown in this figure (8), the increase in the cycle c.o.p is small in the first part of the curves up to (10 degrees), then the cycle c.o.p increases sharply. also, there are higher values of the cycle c.o.p in the second part of the curves. in the other words, for increasing inclination angle (0o) up to (15o) there is a continuous increase in the cycle c.o.p. additionally, it is found that there is a peak value of inclination angle (at θ=15o). then, the increase of (θ) more than (15) degree leads to decrease in the cycle c.o.p. this can be attributed to two reasons: the first , the varied parameters include the inlet air velocity profile and the air split between the upper and lower parts of the condenser, when the inclination angle of the air guide net changed, that means there was a significant difference in the amount of air flowing through the upper side and lower side of the condenser, i.e. more air passed through the upper part of the condenser than the lower part, and the upper part of the condenser had a higher air flow rate than the lower part. thus, the upper part of the condenser is therefore capable of transferring a significant amount of heat which results in more heat dissipation from the condenser. this unbalanced air flow because the cycle working fluid (r134a) entering the upper part of the condenser has a lower level of superheat. the second reason is the redirecting air flow toward the low velocity area at the core of the condenser, as a result of changing the inclination angle of the air guide net. this low velocity area is caused by the hub of the condenser fan. therefore, it can be concluded that, different face-air velocity distributions can be reached by various air guide net sizes and different inclination angles of the air guide net. as shown in figure (8), at a certain air guide net inclination angle (0o-15o), the cycle c.o.p of the a/c system increases, i.e., there is a peak value of inclination angle (15o) . therefore, it is reasonable to predict that the air side heat transfer coefficient can be increased roundly when the face-air velocity distribution through the condenser can be adjusted of (13o to 170o) air guide net inclination angle. that means at this mahmoud maustafa mahdi al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 8999 (2019) 96 angle of inclination, the air side heat transfer coefficient of the condenser increases, therefore the thermal performance of the condenser (denoted by the air side convection heat transfer coefficient) will increase, if the face air velocity through the condenser is adjusted of the case to (15o) air guide net inclination angle. at this angle, the face air velocity distribution increases from bottom to top of the condenser, i.e the face air velocity distribution affects the thermoperformance of the condenser, which in turn affects the performance of the a/c system. therefore, the air velocity redistribution can be employed as an important rule for the enhancement of the thermal performance of the condenser component of the a/c system which leads to enhancement of the c.o.p of the a/c system. in addition, it can be observed that the cycle c.o.p of the a/c system with the air guide for sample (2) is larger than that for sample (1) and sample (3) at all inclination angles. the cycle c.o.p of the a/c system with the air guide net for sample (2) is about (12%) more than that for the other samples (1 and 2) at (15o) inclination angle. fig. 8. variation of cycle c.o.p with inclination angle. 4.4 the effect of air guide net on the input electric power in this section, the electrical power consumption by the a/c system was evaluated for the two cases, namely without and with air guide net in front of the condenser face. in order to assess the effect of using the air guide net on the input electrical power, and to evaluate the reduction of input electrical power that results from the improvement of the cycle c.o.p of a/c systems, figure (9) is plotted. this figure shows the representation of the two cases without and with air guide net and for three different air guide net sizes at constant inlet air temperature through the condenser face. this figure depicts the comparison between the a/c system without and with air guide net. it is cleary shown that the a/c system with an air guide operates with a lower input electrical power comparing with the a/c system without air guide net. that means the a/c system without air guide net consumes a higher power than that the a/c system with air guide net. it is obvious from this figure that there is a magical increase in the electrical power for the a/c system without using air guide net compared to the a/c system using air guide net. also, from figure (9), it can be seen that the less electrical power consumption is in (sample 3) for the case (c), the a/c system with using air guide net (sample 2) and more input electrical power consumption in (sample 1) for the a/c system without using the air guide net. the maximum input electrical power is about (1739 watt) in the case of the a/c system without air guide net, and the minimum input electrical power is about (1550 watt) in the case of the a/c system using the guide net (sample 2). this reduction in the input electrical power to the a/c system is explained below. as mentioned in previous sections, by using the air guide net, an improvement in the heat dissipation from the condenser is observed during which the discharge temperature of the working fluid (r134a) has been reduced by studying the p-h diagram of working fluid (r134 a). it is known that the lower discharge temperature would reduce the specific volume of the refrigerant working fluid and increase the volumetric efficiency of the compressor, so less power would by consumed at the compressor. and because the compressor consumes the most power of the a/c system, the input electrical power would be reduced. a similar trend can be seen for the percentage reduction of input electrical power to the a/c system in figure (10). it can be seen from this figure that for the a/c system with the air guide net (sample 1), the input electrical power reduced by about (2.8%) in comparison with the a/c system without using the guide net, while for the a/c system using air guide net (sample 2) , the reduction is about (10.1%) , also, for the a/c system using air guide net (sample 3) , the reduction is about (7.9%).thus all results above, show that the a/c system with an air guide net mahmoud maustafa mahdi al-khwarizmi engineering journal, vol. 15, no. 2, p.p. 8999 (2019) 97 (sample 2) have a significantly higher percentage reduction in input electrical power than other a/c system with air guide net (sample 1 and 3). fig. 9. graphical representation of the power requirement in the compressor. fig. 10. graphical representation of percentage of reduction in the compressor power requirement. 5. conclusions an experimental investigation was conducted on an automobile air-conditioning system without and with an air guide net installed in front of the condenser face to analyze their performance in terms of the coefficient of performance (c.o.p) and power consumption. from the previous discussion, it can be concluded: 1the c.o.p of the a/c system has been increased by (13%) for air guide net (sample 1), (17%) for air guide net (sample 2) and (14%) for air guide net (sample 3). 2the c.o.p is found to be a strong function of air guide net inclination angle especially in the range (10o – 20o). 3it is found that in order to obtain a high c.o.p, it is necessary to orient the air guide net at (15o) inclination angle. 4the a/c system with an air guide net manifested a significant effect on the power consumption. it is obtained that the power consumption in the compressor has been reduced by (2.8%) for air guide net (sample 1), (10%) for air guide net (sample 2) and (7.9%) for air guide net (sample 3). 6. references [1] alison s., kim t. and ulrich s., energy saving measures for automotive air conditioning (ac) system in the tropic, 15th international refrigeration and air conditioning conference at purdu, july 14-17, 2014. 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[19] zhaoying z., and jianguo y., the effect of face-air velocity distribution on heat transfer performance of air-cooled condensers, international journal of heat and technology, 2015, vol.33, no.1, pp 55-62. )2019( 8999، صفحة 2د، العد15دجلة الخوارزمي الهندسية المجلم محمود مصطفى مهدي 99 اتالهواء امام المكثف على اداء منظومة تبريد السيار ةستعمال شبكة موجاتأثير **مير عبد جدوعأ *محمود مصطفى مهدي الجامعة التكنولوجيةقسم هندسة الكهروميكانيك/ *،** mahmoud_mahdi74@yahoo.com :البريد االلكتروني * en_ameerabed@yahoo.com :البريد االلكتروني ** خالصةال ء هوا ةبكة موجشستعمال انتقال الحرارة الهوائي وذلك بامن خالل تحسين لمنظومة تبريد السيارة في هذا البحث تم التركيز على تحسين أداء المكثف غير أقطارها وبذلك تأن هذه الفتحات الدائرية يمكن وضعت أمام وجه المكثف. أن شبكة موجه الهواء تحتوي على فتحات لمرور الهواء ذات شكل دائري ين من ظومة تحت نوعحصت المنفختيار األداء لمنظومة التبريد عملياً حيث ام يمكن دراسة تأثير تغير حجم هذه الفتحات على أداء المنظومة. في هذا العمل ت لنوعين انظومة لهذين داء المختبارات .النوع األول بدون وضع شبكة موجه الهواء ، والثانية مع وضع شبكة موجه الهواء أمام وجه المكثف ، تم مقارنة أاال أحجام ةتجارب العملية تضمن ثالثختبارات ، فأن البالنسبة للنوع الثاني من اال ر الطاقة المصروفة بالدورةختبارات من خالل معامل أداء الدورة ومقدامن اال فقد تماداً على التجارب العمليةعا. سم) مع بقاء مسافة دخول الهواء ثابتة لكل األحجام 3.5و ٣، ٢( أقطار لمرور الهواء ةمن شبكة موجه الهواء أي ثالث راسة د نلعملي تضملجانب ااختبارات. وعليه فأن اسة تأثير تغير زاوية شبكة موجه الهواء على أداء المنظومة وبالتحديد للنوع الثاني من االتضمنت الدر ومة التبريد وذلكدرجة) أن وجود شبكة موجه الهواء أمام وجه المكثف قد عمل على تحسين أداء منظ ٠٢٠، ٠١٥، ٠١٠، ٠٥، ٠٠تأثير خمس زوايا ميل ( وجه مستخدام شبكة اوبدون الى ذلك فأن مقدار الطاقة الكهربائية المستهلكة (المصروفة) من قبل منظومة التبريد فضالً عنلكل أحجام شبكة موجه الهواء نظومة ند تشغيل المعد تحسن قنخفاض في الطاقة المصروفة ا مع منظومة التبريد ذات شبكة موجه الهواء. وبينت النتائج أن االالهواء تم حسابها ثم مقارنته مع شبكة موجه الهواء. microsoft word ???? ??????31-44 al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 17, no. 2, june, (2021) p. p. 31-44 modeling and simulation for performance evaluation of optical quantum channels in quantum key distribution systems adil fadhil mushatet* shelan khasro tawfeeq ** *al-khwarizmi engineering college/ university of baghdad/ iraq ** institute of laser for postgraduate studies/ university of baghdad/ iraq *email: adilfadhil@kecbu.uobaghdad.edu.iq **email: shelan.khasro@ilps.uobaghdad.edu.iq )accepted 16 april 2021received 13 march 2021; revised 13 april 2021; ( https://doi.org/10.22153/kej.2021.05.001 abstract in this research work, a simulator with time-domain visualizers and configurable parameters using a continuous time simulation approach with matlab r2019a is presented for modeling and investigating the performance of optical fiber and free-space quantum channels as a part of a generic quantum key distribution system simulator. the modeled optical fiber quantum channel is characterized with a maximum allowable distance of 150 km with 0.2 db/km at =1550nm. while, at =900nm and =830nm the attenuation values are 2 db/km and 3 db/km respectively. the modeled free space quantum channel is characterized at 0.1 db/km at =860 nm with maximum allowable distance of 150 km also. the simulator was investigated in terms of the execution of the bb84 protocol based on polarizing encoding with consideration of the optical fiber and free-space quantum channel imperfections and losses by estimating the quantum bit error rate and final secure key. this work shows a general repeatable modeling process for significant performance evaluation. the most remarkable result that emerged from the simulated data generated and detected is that the modeling process provides guidance for optical quantum channels design and characterization for other quantum key distribution protocols. keywords: optical quantum channel, modeling, quantum bit error rate, quantum key distribution. 1. introduction quantum key distribution (qkd), the most advanced technology in the field of quantum information, allows two remote parties to exchange unconditionally secure key and subsequently check their secrecy based on the principles of quantum mechanics [1, 2]. in qkd the quantum channel is not used directly to send meaningful message. it is rather used to transmit a supply of random bits between two users who share no secret information in advance. the reason for naming this channel as a quantum channel because it is used to distribute the shared key between two parities using ideal single photons or high level of attenuation to reach the quantum level of optical pulses [3]. to implement qkd in real-life, ideal models should be used to verify security proofs, which is not the case in reality, as a noisy communication channel in which optical fiber channels suffer from that polarization of photons is changed with the increase of fiber length due to the birefringence character and free space channel losses due to atmospheric effects and diffraction attenuation, opening the door for different eavesdropping attacks to be launched against qkd systems. for this reason, the main challenge is to implement a simulation environment to investigate the optical quantum channel performance. solving this challenge will enable a swift simulation and evaluation of the quantum channel behavioral operation.  adil fadhil mushatet al-khwarizmi engineering journal, vol. 17, no. 2, p.p. 3144(2021)     32 the aim of this work is to model environment gui tool supports with time-domain plotters to simulate the optical pulses generation and transmission processes for individual testing purpose to simulate both quantum channels, optical fiber (of) and free space (fs), performance in qkd systems in terms of quantum bit error rate (𝑄𝐵𝐸𝑅) and final secure key considering the limitations imposed by using practical quantum channels. this research presents a quantum free space channel simulator which to the best of our knowledge, was not considered previously within other qkd simulators. few simulation efforts were reported in related literature to develop a model aimed to investigate the optical fiber quantum channels operation performance. for example, nathaniel t sorensen et al. have presented two approaches to simulate the optical fiber quantum channels, first one deals with the photons as wave packets while the other as discrete particles [4]. jonathan c denton et al. introduced a model to investigate the performance of space-based quantum channels in qkd systems taking into consideration the atmosphere losses and the selection of the orbit [5]. in contrast to the simulators mentioned above that concentrate on the theoretical investigations without connection to the application field, this work aims to get the simulated information generated and detected by real and commercially available physical components. the most important challenge in this work was how the simulator can address the effects due to the propagation of the laser pulses, optical components functions and the behavior of complex interacting single-photon detectors software process present within this system. 2. the optical quantum channel conceptual model the optical quantum channel is a passive component with one input and one output as shown in the corresponding conceptual model of figure (1). fig. 1. optical quantum channel conceptual model. regarding of channel, from the conceptual model diagram, the attenuated coherent optical pulses that are usually used in the qkd system, are generated via modeled pulsed laser source which consists of two parts, binary pseudo random sequence (bprs) generation unit and laser device. the modeled bprs unit generates a binary non-return–to-zero (nrz) sequence of n bits with a defined pulse repetition rate. based on the input from the bprs unit, the laser source generates gaussian optical pulse trains with peak optical power (𝑃 ) in the range of (pw) with (ns) pulse duration with the possibility to support different optical wavelengths (). each pulse is generated with known shape, intensity, polarization, period and global phase. to simulate the coherent optical pulse used in this work, the model proposed by douglas d.hodson [6, 7] is used. the approximation function of the coherent optical pulse has the following form, 𝐸 0, 𝑡 𝐸 𝑒 𝑒 |𝑔 𝑡 | …(1) where |g (t)| represents the optical pulse gaussian shape, |𝑔 𝑡 | ∆ √ 𝑒 ∆ …(2) where 𝐸 is the pulse maximum electric field, 𝜃 is the phase offset of the pulse, 𝛼 is the angle of the vector to the 𝑥 axis, 𝛷 is the relative phase between the 𝑥 and 𝑦 components of the electric field and 𝜔 is the angular frequency. the coherent optical pulses are attenuated by the modeled optical power attenuator (pa) and are sent to the modeled of quantum channel. the propagated optical pulses will be under the influence of fiber attenuation and polarization rotation distortions as a result of fiber geometry and its material characteristics. the output optical pulses will be heavily attenuated as the transmission distance increased. while the polarization of the optical pulses lunched to the fiber will be randomly rotated along the length of the of quantum channel by an angle (𝜗) when the linearly polarized optical pulses are lunched by the qkd transmitter. as the inputs to the simulation model, the following parameters were considered, optical pulse time profile with linear polarization as defined in eq.(1) with 𝑃 in (mw), transmitted  in nm, channel distance (𝐿) input port output port optical quantum channel  adil fadhil mushatet al-khwarizmi engineering journal, vol. 17, no. 2, p.p. 3144(2021)     33 and the attenuation constant of the fiber (per km) (𝛼 ). these parameters can be set by the user in the modeling gui tool. for the fs channel, the incoming optical pulses from the qkd transmitter will enter the input port and propagate along with it. the transmitted optical pulses will be under the influence of all atmospheric attenuation effects and attenuation due to diffraction. the output optical pulses will be heavily attenuated as the transmission distance increases. while the polarization of the linearly polarized optical pulses launched to space will not change along the path. in this model, the losses due to different atmospheric conditions such as the losses due to atmospheric absorption and scattering 𝛿 , space loss (𝛿 ), weather impairments and finally the beam divergence losses due to diffraction 𝛿 will be included. 3. the optical quantum channel mathematical models this section outlines the mathematical model of a single-mode fiber (smf) and fs atmospheric model that takes into account the atmospheric and diffraction losses that are believed to be important for the modeling of the qkd quantum channel. a. the optical fiber channel fiber-based qkd systems are affected by the attenuation which is mainly raised by the absorption and scattering losses. almost 90% of total attenuation is due to scattering losses only. with respect to the dispersion in smf, real smf has a core with a semi-elliptical shape profile rather than an ideal circular core; this, in turn, leads to eliminate the degeneracy of orthogonal modes and leads to different groups velocities. this results in pulse broadening and this effect is known as polarization mode dispersion (pmd) [8]. in this work, the modeled of quantum channel has been designed as a normal smf, not as a polarization-maintaining fiber. thus, the polarization of the transmitted optical pulses is randomly rotated due to pmd and drift from their original encoded basis. in addition, the signal attenuation effect due to of losses is included in the of quantum channel model. the impact of these types of errors on the channel performance enhances the 𝑄𝐵𝐸𝑅 of the qkd system and reduce the final shared secure key. the coherent optical pulse defined in eq. (1) represents the input to the of quantum channel model. for a non-dispersive medium; 𝜃 will be constant at all spatial points 𝑧, .i.e., assumed (0 degrees) in this work. for the sake of simplicity, |𝑔 𝑡 | the term is not considered for the next steps in this model. from the coherent optical pulse representation, the signal parameters that will be affected by the of quantum channel are 𝐸 and 𝛼 .. to find the behavior of the transmitted optical pulses after passing through the of quantum channel, the following operation on the coherent optical pulse jones matrix will be carried out taking into account the amount of the attenuation coefficient and its relation to the transmission distance in addition to the effect of the random polarization variation by an angle (𝜗). 𝐸 𝐸 𝑒 𝑒 |𝑔 𝑡 | cos 𝛼 . 𝜗 sin 𝛼 . 𝜗 𝑒 10 / …(3) thus, the optical signal form at the of quantum channel output port will be as follows: 𝐸 𝐸 𝛼 𝑒 𝑒 |𝑔 𝑡 | cos 𝛼 . 𝜗 sin 𝛼 . 𝜗 𝑒 …(4) b. the free-space quantum channel as a solution to the attenuation caused in the fiberbased qkd systems, a free space channel allows greater communication distances because the atmosphere has low absorption in certain wavelengths. in addition, the atmosphere has a nearly non-birefringent character which ensures the conservation of the photon’s polarization state [9, 10]. the modeled fs quantum channel is characterized at 0.1 db attenuation per km at  =860 nm. in addition to the very low attenuation level feature at this , the commercial singlephoton detector (spd) operating within (600900nm) window show better operation performance with higher quantum detection efficiency reaching 70%. in this model, the channel transmittance model must take into consideration all impairments that affect the performance of the fs quantum channel for better simulation of the behavior of a terrestrial fs quantum channel. in this model, the losses due to different atmospheric conditions such as the losses due to atmospheric absorption and scattering, space loss, weather impairments and finally the  adil fadhil mushatet al-khwarizmi engineering journal, vol. 17, no. 2, p.p. 3144(2021)     34 beam divergence losses due to diffraction will be included. the main source of attenuating of the optical signals transmitted through the fs quantum channel is the absorption and scattering due to dust, aerosols, carbon dioxide, etc. [11]. the propagated light photons will interact with the atmospheric particles which lead to scatter and absorb part of these photons [12]. thus, the amount of the optical power received at the detector will be investigated by beer-lambert law which relates the optical signal transmittance to the length of the fs link as follows [11], 𝑃 𝑃 𝑒 …(5) where 𝑂𝐷 is the optical depth, 𝑃 and 𝑃 are the received and transmitted power respectively [12], ∴ 𝑇 𝑒 … (6) where 𝑇 is known as the transmittance of the link which defines the amount of the transmitted light power along the channel [11]. the atmospheric attenuation coefficient (𝜎  ) is related to this atmospheric transmittance by [12], 𝑇 𝑒  … (7) the overall 𝜎  will sum up all the absorption and scattering coefficients within the atmosphere [11, 12], 𝜎  𝜎  𝜎  𝛽  𝛽  …(8) where first two terms show the aerosol and molecular absorption coefficients, respectively, and the last two terms are the aerosol and molecular scattering coefficients, respectively. as a result, the total attenuation losses for the transmitted optical beam in db can be calculated as [11, 12], 𝛿 10 log 𝑇 …(9) to calculate the attenuation of optical signal propagating through fs quantum channel due to atmospheric effects, the channel attenuation 𝛿 in (db/km) can be expressed as [11, 12], 𝛿 10 log …(10) ∴ 𝛿 10 log 𝑒  … (11) finally, the diffraction-limited beam divergence loss in db can be defined as [10], 𝛿 10 log 𝑒 𝑒 𝑒 𝑒 …(12) where 𝛾𝑡, 𝑟 , , , αt, r , , , 𝑤 𝑅 𝑎𝑛𝑑 𝑤 √  [10] where the subscript 𝑡 refers to the transmit telescope and 𝑟 is the receive one that are used in free space qkd systems. 𝑅 and 𝑏 are the primary and secondary mirrors radii, respectively, 𝑤 , refers to the beam radius at the transmission or reception side. thus, the total channel attenuation is given by [9, 10], 𝛿 𝛿 𝛿 𝛿 𝛿 … (13) where 𝛿 is the single-photon detection efficiency of the spd. a list of all the required parameters as inputs to the simulation model is found in table 1. the telescope’s primary and secondary mirror radius in addition to 𝛿 are taken from silex experiment and tenerife's telescope [9, 13, 14] that are considered as global standard experiments for fsqkd systems. 𝐿 and 𝛿 can be set by the user in the modeled gui tool. table 1, input parameters for fs quantum channel modeling to find the behavior of the transmitted optical pulses after passing through the fs link, the following operation on the transmitted coherent pulse jones matrix will be carried out taking into account the amount all attenuation effects, parameter value 𝑃 1 mw  860 nm telescope’s primary mirror radius 50 cm telescope’s secondary mirror radius 5 cm beam radius at the transmitter 50 cm beam radius at the receiver for 𝐿=50km 4 cm for 𝐿=100km 7.75cm for 𝐿=150km11.62cm single-photon detector efficiency 70% @ =860 nm 𝛿 1 db  adil fadhil mushatet al-khwarizmi engineering journal, vol. 17, no. 2, p.p. 3144(2021)     35 𝐸 𝐸 𝑒 𝑒 |𝑔 𝑡 | cos 𝛼 . sin 𝛼 . 𝑒 𝛿 …(14) 4. the structured flow of the modeling process and the methodology used the purpose of optical quantum channel modeling is to efficiently relate the system’s practical considerations, software design with the theoretical fundamentals such as the optical pulse generation and transmission, the optical pulse properties, the operation principles of the optical components and the system environment conditions. the optical quantum channel simulator modeling process involves a set of actions. the representation of these actions is known as the software development model as shown in-tier architecture in figure (2). in this section, the structuring flow of the software development model that has been utilized to implement this simulation tool will be explained in addition to the methodology used in this research work. fig. 2. optical quantum channel simulator software. in general, there are four actions required to implement any programming model. firstly, the model specifications must be characterized, secondly, the model design should suit the user prerequisites, thirdly, the designed model must be verified and tested and finally, the implemented model must be flexible and possible to be developed [15, 16]. each stage will be explained as follows: 4.1 user needs analysis in this stage, the user prerequisites that the designed optical quantum channel simulator can achieve are analyzed. the simulator requirements focused on successfully investigate the channel performance by estimating qber and final secure key for the following cases, of quantum channel imperfections such as the polarization rotation and attenuation and fs quantum channel losses due to atmospheric effects and diffraction attenuation . 4.2 model specifications in this stage, the inputs provided from the simulator users with the expected outcomes will be defined. table 2 represents the simulator specifications as inputs and outputs for optical quantum channels simulators. table 2, inputs and outputs for the optical quantum channel simulator. simulator inputs simulator outputs  𝑄𝐵𝐸𝑅 𝐿 sifted bits rate for bb84 protocol (keyraw) 𝛼 4.3. model design according to this stage, the previous two stages are related to the hardware components for the simulator final design. in this work, the modular and hierarchical approaches were used as architecture for the simulator. using this approach, the user will be flexible enough to build different implementation scenarios and the model developer will easily modify and extend the model. figure (3) shows the designed model layers that consist of three layers each with a specific objective. the outer layer represents the application field selected by the user. in this work, only the qkd system for the bb84 protocol is demonstrated. the middle layer represents the main simulation operation phases that involve optical signal generation, transmission and detection. these steps were built using various modules which consist of different integrated physical modeled components. for example, the optical signal preparation and generation phases can be conducted using the transmitter module which consists of bprs, pulsed laser source and pa. the last layer is established using different physical electrical and optical components. this  adil fadhil mushatet al-khwarizmi engineering journal, vol. 17, no. 2, p.p. 3144(2021)     36 layer is considered as the construction of the modules at layer 2. the continuous time-domain simulation approach that was utilized in this work was a time and computation-consuming approach because hundreds of optical pulses will be generated and transmitted through the system's components. fig. 3. qkd simulator reference layers. 4.4 model verification and validation process the credibility of the optical quantum channel simulation model and its results are verified using the known verification and validation steps. the approach that has been used for model verification was by running the model under different conditions by applying inputs and checking the outcomes [15, 16, 17]. the recorded results will show how the model is programmed in a sufficiently and correctly way by determining the response of the model to the input parameters. in this research, a matlab compiler was used to prove the model verification by testing the code as recommended by sargent and balci [15, 16]. for the validation technique, the approach that was applied to the mathematical models as recommended by sargent [15] was established with the help of the specialized references and publications in the field, commercial data sheets to define the allowed input and output limits in addition to the desired specifications to prove that the postulates and the theoretical concepts on which mathematical models are based were correct. the methodology for the modeling process for each component and module that was followed in this research work is similar as shown in figure (4). bb84 protocol transmissiongeneration  detection    prs  pulsed laser source  linear polarizer optical power attenuator  optical fiber channel  free space channel single photon avalanche detector  adil fadhil mushatet al-khwarizmi engineering journal, vol. 17, no. 2, p.p. 3144(2021)     37 fig. 4. modeling process steps. gui: graphical user interface. test the validity of the conceptual and the mathematical models final optical quantum channel simulator form is the component or module operation validity is acceptable? convert the conceptual & mathematical models to the corresponding matlab code yes yes no are the conceptual & mathematical models valid? is the component code is verified? collecting information about the optical quantum channel to be modeled conceptual model design for the optical quantum channel to be modeled mathematical model design for the optical quantum channel to be modeled convert the conceptual & mathematical models to the corresponding yes no final gui implementation no  adil fadhil mushatet al-khwarizmi engineering journal, vol. 17, no. 2, p.p. 3144(2021)     38 final optical quantum channel simulator 5. results and discussion the purpose of this section is to present the results with the analysis of modeling the optical quantum channel. 5.1. simulator testing fig. 5. of quantum channel simulator window. the optical quantum channel model has been implemented with a friendly gui as shown in figure (5) which includes of and fs quantum channels. this interface with its configurable editing objects is responsible to allow users to configure the of and fs quantum channels model to enable the attenuation effect in 𝛼 per 𝑘𝑚 and to decide the of quantum channel 𝐿 in km. the user allowed 𝛼 values vs.  are listed within the gui. for the simulation of the polarization rotation effect, the gui plotters will not be able to clearly show the alteration in polarization in the transmitted optical pulses over the of quantum channel. otherwise, the effect of this error type will be significant on the qkd system performance by reducing both qber and final shared secure key. two tests were applied to verify the modeled of quantum channel model to simulate the of operation. the incoming optical pulses from the qkd transmitter are linearly polarized with prr= 100 khz and p_peak=1mw. figure (6a) illustrates test 1 set up to investigate the attenuation due to absorption and scattering in the transmitted optical pulses after passing through the of quantum channel model at  =1550 nm. in this test, for 100 km length fiber and α_p =0.2db/km, the output power is equal to 0.01mw as shown in figure (6b). fig. 6. test 1 (a) gui set up (b) result for of quantum channel for l =100km and α_p=0.2 db/km. figure (7a) illustrates test 2 set up to examine the of quantum channel model performance for =900 nm. in this test, for 100 km long fiber and α_p=2 db/km, the output power is equal to 10-23 w as shown in figure (7b).  adil fadhil mushatet al-khwarizmi engineering journal, vol. 17, no. 2, p.p. 3144(2021)     39 (a) (b) fig. 7. test 2 (a) gui set up (b) result for of quantum channel for l=100km and α_p=2 db/km. figure (8a) illustrates test 3 set up to examine the of quantum channel model performance for =830 nm. in this test, for 100 km long fiber and 𝛼 =3 db/km, the output power is equal to 10 w as shown in figure (8b). a) (b) ( fig. 8. test 3 (a) gui set up (b) result for for of quantum channel for l=100km and α_p=3 db/km figure (9a) illustrates test 4 set up that is used the same parameters as used in last two tests to investigate the attenuation in the transmitted optical pulses after passing through the fs quantum channel model at =860 nm. in this test, for 50 km link length, the output power is equal to 0.02nw as shown in (9b).  adil fadhil mushatet al-khwarizmi engineering journal, vol. 17, no. 2, p.p. 3144(2021)     40 (a) (b) fig. 9. test 4 (a) gui set up (b) result for fs quantum channel for l =50km. figure (10a) illustrates test 5 set up. in this test, for 100 km fs quantum channel length, the output power is equal to 2.1 f w as shown in (10b). )b ((a) fig. 10. test 5 (a) gui set up (b) result for fs quantum channel for l=100km. (a) (b) fig. 11. test 6 (a) gui set up (b) result for fs quantum channel for l =150km.  adil fadhil mushatet al-khwarizmi engineering journal, vol. 17, no. 2, p.p. 3144(2021)     41 figure (11a) illustrates test 6 set up. in this test, for 150 km link length, the output power is equal to 300 attow as shown in (11b). the results obtained from the previous tests illustrate the performance degradation of of and fs quantum channels due to the effect of the attenuation represented by fiber absorption and scattering and atmospheric, weather conditions in addition to the beam divergence due to diffraction in the fs channel as 𝐿 increased. 5.2 investigation of the system performance under the effect of the polarization rotation the effect of the random polarization rotation for the optical pulses traveled inside the of link within a complete qkd system based on bb84 protocol will be explained in terms of investigating the system quantum bit error rate after the sifting phase (qbersk) which can be calculated by divide the sifted wrong bits to the total number of the received sifted bits. the simulator configuration parameters that have been used in this experiment are, 𝜆= 830 nm, 𝐿=20 km, 𝑃𝑅𝑅= 10 mhz. this effect was modeled using an embedded sub-function within the system to simulate the polarization rotation mechanism where the range of the polarization rotation in degree is from (0° → 45°). table 3 summarizes the amount of the polarization rotation in the degree that has been added to the polarization of the generated optical pulses in addition to the resultant qbersk where the polarization of the propagated optical pulses within the of link is changed from its original state to a new state randomly. the estimated qbersk random behavior shows the effect of transmitting wrong polarization states on the system performance. table 3, the effect of the optical pulses polarization rotation on the system qbersk random rotation of the polarization state inside of channel qbersk (%) 1° 41 4° 60 5° 64 37° 51 8° 47 4° 55 6° 58 5.3 investigation and analysis of system parameters under the effect of quantum channel losses this study is conducted to examine the relation between the performance of the system represented by the ratio of the dark-count rate to the detection probability (qberspd ) and the generated keyraw with average photon number per pulse (𝑁 ) and 𝐿 system parameters. qberspd can be defined as [18]: 𝑄𝐵𝐸𝑅 … (15) where 𝑃 : is the probability of recording a dark count per time window and per detector 𝑛: refers to the number of detectors. 𝑁 : mean photon number per pulse 𝜂 : is the probability of the photon’s being detected 𝑡 : the transfer efficiency between alice's output and bob's detectors and can be defined as [18]: 𝑡 10 … (16) where 𝛼 is the fiber attenuation constant per km, 𝐿 is the link length in km and 𝐿 is bob's internal loss in db. 𝑁 is preferred to be in the range (0.1-1) to ensure security for qkd systems. both quantum channels types have been used to perform this simulation study i.e. of channel was operated at 1550nm and fs channel was operated at 860nm. table 4 shows the main simulation input parameters. table 4, simulation study input parameters parameter value 𝜆 1550nm, 860nm 𝑃𝑅𝑅 0.1 mhz, 2 mhz, 5 mhz 𝑁 0.1, 0.2, 0.4 𝐿 20 km, 40 km, 60 km, figure (12) illustrates the obtained results that indicate the transmission distance and the amount of the shared keyraw will be limited as a result of the decline in the system performance, which is represented in increasing calculated quantum bit error rate with the consideration of qberspd as the channel length increases. compared to of channel, fs channel is not suitable for longdistance operation as a result of increasing the noise and the interference with increasing 𝐿. on the other hand, 𝑁 = 0.1 is preferred for high  adil fadhil mushatet al-khwarizmi engineering journal, vol. 17, no. 2, p.p. 3144(2021)     42 security issues although the exchanged keyraw is small compared to 𝑁 = 0.2 and 0.4 (a) (b) fig. 12. keyraw vs. qberspd (%) at different l and n_0(a) λ=1550nm (of) (b) λ=860nm (fs). 6. conclusion in this research, a modeling tool of the optical quantum channel was implemented, tested and integrated within a modeled qkd-bb84 practical set-up. a set of tests were conducted to investigate the simulator validation in terms of 𝑄𝐵𝐸𝑅 calculation and final secure key extraction under different operation conditions such as of attenuation and pmd losses and fs atmospheric and diffraction losses that are believed to be important for the modeling of the qkd quantum channel. the most remarkable result to emerge from the data is that the modeling process provides guidance for optical quantum channel design and characterization. it is possible to conclude that the simulation methodology that has been used within this work is efficient to describe the modeled system components details but at the same time it is processing time and resources consuming. thus, the recommended approach is to model such a system is to use an approach that deals with the simulation operations as synchronized discrete events organized in a logical form. this method was used because basically the modeled optical quantum channel is not intended to simulate any real optical quantum channel but to evaluate the capabilities of the modeled optical quantum channel presented in this work. for further development of this work, the simulator model performance can be developed by using a discrete event approach supported by more general programming languages such as c++ to increase the simulator reality and trying to model underwater quantum channel and embed it within a general qkd modeling tool.  adil fadhil mushatet al-khwarizmi engineering journal, vol. 17, no. 2, p.p. 3144(2021)     43 7. references [1] douglas d hodson, michael r grimaila, logan o mailloux, colin v mclaughlin, and gerald baumgartner, "modeling quantum optics for quantum key distribution system simulation,"journal of defense modeling and simulation: applications, methodology, technology", vol. 16, issue 1,2017. [2] nicolas gisin, gre´ goire ribordy, wolfgang tittel, and hugo zbinden," quantum cryptography", reviews of modern physics, vol. 74, january 2002. [3] h. lo, “unconditional security of quantum key distribution over arbitrarily long distances,” science (80-. )., vol. 283, no. 5410, p. 20502056, 1999, doi: 10.1126/science.283.5410.2050. [4] nathaniel t sorensen1 and michael r grimaila, "discrete event simulation of the quantum channel within a quantum key distribution system," the journal of defense modeling and simulation: applications, methodology, technology, vol. 12, issue 4, page(s): 481-488, 2015. [5] jonathan c denton, douglas d hodson, richard g cobb, logan o mailloux, michael r grimaila, and gerald baumgartner, " a model to estimate performance of space-based quantum communication protocols including quantum key distribution systems," the journal of defense modeling and simulation: applications, methodology, technology, vol. 16, issue1, page(s): 5-13, 2017. [6] d. d. hodson, m. r. grimaila, l. o. mailloux, c. v mclaughlin, and g. baumgartner, “modeling quantum optics for quantum key distribution system simulation,” j. def. model. simul., vol. 16, no. 1, pp. 15– 26, jan. 2017, doi: 10.1177/1548512916684561. [7] l. mailloux, m. grimaila, d. hodson, l. e. dazzio-cornn, c. mclaughlin, and l. dazziocornn, “modeling continuous time optical pulses in a quantum key distribution discrete event simulation,” 2014. [8] i. p. kaminow, t. li, and a. e. willner, optical fiber telecommunications v a, 5th edition. elsevier inc., 2008. [9] s. ali and m. r. b. wahiddin, “fiber and free-space practical decoy state qkd for both bb84 and sarg04 protocols,” eur. phys. j. d, vol. 60, no. 2, pp. 405–410, 2010, doi: 10.1140/epjd/e2010-00214-5. [10] l. moli-sanchez, a. rodriguez-alonso, and g. seco-granados, “performance analysis of quantum cryptography protocols in optical earth-satellite and intersatellite links,” ieee j. sel. areas commun., vol. 27, no. 9, pp. 1582–1590, 2009, doi: 10.1109/jsac.2009.091208. [11] s. k. jain, hemani kaushal virander kumar, free space optical communication ,optical networks, 1st edition. springer, 2017. [12] s. r. by z. ghassemlooy, w. popoola, optical wireless communications:system and channel modelling with matlab, 1st edition. crc press, 2012. [13] t. schmitt-manderbach et al., “experimental demonstration of free-space decoy-state quantum key distribution over 144 km,” phys. rev. lett., vol. 98, no. 1, p. 10504, jan. 2007, doi: 10.1103/physrevlett.98.010504. [14] a. i. khaleel and s. k. tawfeeq, “key rate estimation of measurement-deviceindependent quantum key distribution protocol in satellite-earth and intersatellite links,” int. j. quantum inf., vol. 16, no. 03, p. 1850027, apr. 2018, doi:10.1142/s0219749918500272. [15] r. g. sargent, “verification and validation of simulation models,” j. simul., vol.7, no. 1, pp. 12–24, 2013, doi: 10.1057/jos.2012.20. [16] o. balci, “principles and techniques of simulation validation, verification, and testing,” in winter simulation conference proceedings, 1995., 1995, pp. 147–154, doi:10.1109/wsc.1995.478717. [17] jerry banks, "handbook of simulation principles, methodolgy, advances, applications and practice", john willey and son inc., 1998. [18] g. ribordy, j.-d. gautier, n. gisin, o. guinnard, and h. zbinden, “fast and userfriendly quantum key distribution,” j. mod. opt., vol. 47, no. 2–3, pp. 517–531, 2000, doi: 10.1080/09500340008244057.  )2021( 31-44صفحة ،2العدد ،17المجلد الهندسية الخوارزمي جلةم عادل فاضل مشتت   44 منظومات توزيع المفتاح الكمي قنوات األتصال الكمية فيلتقييم اإلداء ل ومحاكاة نمذجة عادل فاضل مشتت* شيالن خسرو توفيق** *قسم هندسة المعلومات واالتصاالت/ كلية الهندسة الخوارزمي/ جامعة بغداد/ العراق العراق /جامعة بغداد /معهد الليزر للدراسات العليا** adilfadhil@kecbu.uobaghdad.edu.iq*البريد االلكتروني: helan.khasro@ilps.uobaghdad.edu.iq**البريد االلكتروني: الصةالخ م ضمن نطاقات توزيع المفتاح الكمي هو أحد أنواع التجفير الكمي والذي يسمح بتبادل آمن للمفتاح الكمي بين مستخدمين تفصل بينهما مسافة كبيرة يستخد والت تحليل لنمذجة, أفتراضية بيئة خلق الضروري من أصبح بالتالي, والحكومية. ,العسكرية األقتصادية المجاالت مثل مشددة أداء امنية من قنوات حقق الكمية ضمن الكمي.االتصال المفتاح توزيع الحر منظومات البصري والفضاء الليف لقنوات االتصال بناء والتحقق من محاكي تم البحثي, العمل في هذا الكمي المفتاح توزيع منظومة من كجزء منفصل الكمية بشكل أختباره لغرض الزمني المجال براسمات المستمر مزود الزمن محاكاة أسلوب بأستخدام ديسيبيل/كم عند ٠٫٢كم كحد أعلى وبمعامل توهين مقداره ١٥٠قناة أتصال الليف البصري صممت بطول يصل الى . matlab2019aوبأستعمال برنامج نانومتر فأن معامل ٨٣٠نانومتر و ٩٠٠الموجية ). بينما عند األطول sm-28نانومتر نسبة الى المواصفات التجارية لليف البصري (١٥٥٠الطول الموجي ٠٫١كم وبمعامل توهين مقداره ١٥٠ديسيبيل/كم على التوالي. تم تصميم قناة اتصال الفضاء الحر الكمية بطول يصل ايضا الى ٣ديسيبيل/كم و ٢التوهين هو مع مالحظة العوامل المؤثرة في أداء المنظومة bb84تنفيذ بروتوكول تم التحقق من عمل المحاكي من خالل نانومتر. ٨٦٠ديسيبيل/كم عند الطول الموجي والفضاء البصري الليف أتصال قنوات وعيوب خسائر األعتبار بنظر االخذ مع النهائي المفتاح وطول الكمي الخطأ نسبة معدل تخمين الحر عن طريق هو أن , بروزاً والمستخلصة من بيانات المحاكاة النتيجة األكثر. ء المنظومات بشكل فعالظهر هذا العمل عملية نمذجة عامة قابلة للتكرار لتقييم أدا الكمية. برتوكوالت في أستخدامها ألمكانية البصرية الكمية القنوات وتوصيف لتصميم المناسبة إألرشادات توفر النمذجة الكميعملية المفتاح . االخرى توزيع أظهرت خطوات التحقق من صحة النتائج لمحاكاة عناصر المنظومة تقارب جيد مع النتائج النظرية المذكورة في المراجع. al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 4, no. 4, pp 1-8 (2008) performance of gas induction in a dual – impeller agitated bioreactor alaa k. mohammed, hassanin ali hussen and safa abid al-rassul genetic engineering and biotechnology/ institute for postgraduate studies / university of baghdad (received 14 january 2008; accepted 11 seotermber 2008) abstract the rate of gas induction was measured in gas-inducing type mechanically agitated contactors provided with two impellers. a reactor of 0.5 m i.d. was used with a working capacity of 60 liters of liquid. tap water was used as the liquid phase, and air was used as the gas phase. the bioreactor mixing system consists of two equal diameter stirrers; the top impeller is shrouded-disk/curved-blade turbine with six evacuated bending blades, while the bottom impeller was disk turbine. the impeller speed was varied in the range of 50 to 800 rpm. the ratio of impeller diameter to tank diameter (d/t) and the submergence (s) of upper impeller from the top were varied. the effects of clearance of lower impeller from the tank bottom (c2) and the impeller spacing (c3, distance between the two impellers) were also varied over a wide range. rate of gas induction (q) was measured for all these combinations. it was found that the rate of gas induction increases with both decreasing in submergence and increasing in the stirrer diameter. while it decreases with both increasing the impeller spacing and the clearance from the bottom. keywords: bioreactor, dual-impeller, suctiontype impeller, fermentor). 1. introduction: in many gas-liquid reacting systems, the recirculation of gas from the head space back into liquid is desired. this can be achieved by using different reactor designs such as sparged loop reactors, surface aerators, and gas-inducing-type mechanically agitated contactors (gimac). the comparison of gimac with other reactors has been reported by saravanan et al. (1994). these reactors are useful for unit processes such as alkylation, ozonolysis, and hydrochlorination where it is desirable to have complete utilization of the solute gas. it is particularly useful for situations where the gas is available at relatively low pressure and the gas is introduced in the contactor by generating a low-pressure region in the vicinity of impeller. many designs of gas inducing impellers have been reported in the published literature (zlokamik and judat, 1967; joshi and sharma, 1977; zundelevich, 1979; joshi, 1980; raidoo., 1987, mundale and joshi, 1995; swapnil et al. 2003; swapnil et al. 2004). these designs include the pipe impeller consisting of a hollow shaft and hollow impeller, the flattened cylindrical impeller, the turbo aerator, the shrouded-disk curved-blade turbine, and the pitched-blade down flow turbine. swapnil and joshi (2004) have examined the different impeller designs and have shown the pitched-blade down flow turbine (pbtd) to be the most energy efficient. however, these reactors having only one impeller need further improvements. the rate of gas induction decreases with an increase in the impeller submergence from the top. therefore, the gas-inducing impeller needs to be as close to the surface as possible. on the other hand, the dispersion ability of the impeller decreases as the impeller is brought closer to the liquid surface. in addition, it is also known that the suspension ability of the gas-inducing impeller is very poor. these limitations of the single-impeller system can be overcome by using a double-impeller system. the top impeller acts as a gas-inducing impeller, and the second impeller distributes the gas bubbles throughout the vessel. thus the functions of gas introduction and gas dispersion are assigned to two different impellers. there is yet another advantage of the second impeller. the alaa k. mohammed al-khwarizmi engineering journal, vol.4, no.4, pp1-8 (2008) 2 second impeller is closer to the bottom and it is more effective for the purpose of solid suspension. thus, the induction, the dispersion, and the suspension ability of the two-impeller system are far superior to those of the single-impeller system. therefore, it was thought desirable to undertake a systematic investigation to optimize the impeller combination. 2. materials and methods: investigations were carried out in 0.5 m i.d. gas-inducing type of mechanically agitated reactors (gimac) of 60 liter capacity. the schematic diagrams of the gimac and the experimental setup are shown in figure 1. the design details of vessels are given in table 1. the prime mover was a dc motor, driven by a thyristor-controlled power source. the speed of rotation of the shaft was controlled by regulating the voltage applied to the armature of the motor by a ten-turn potentiometer. fixed pulleys and twin c section were used to connect the agitator shaft to the motor. the entire device was able to control the speed. the bioreactor mixing system consists of two equal diameter stirrers; the top one is shrouded-disk/curved-blade turbine with six evacuated bending blades as shown in figure 2., while the bottom impeller was disk turbine. the reactor tank, the central draft tube, the aeration wheel disk and hub were made of stainless steel. the air ducts were also stainless steel tubes, which were welded to the disk. the assembly was tinned and the hub was turned to fit a vulcanite sleeve in the bottom guide bearing. the shaft was made of ¾ inch stainless steel pipe. the cap for the introduction of air was bored to a tight running fit. the impeller speed was varied in the range of 50 – 800 rpm. the ratio of impeller diameter to vessel diameter (d/t) was varied from 0.15 to 0.35 .the lower impeller clearance from the tank bottom (c1) was also varied over a wide range (c1 =t/4 to t/8). the effect of top impeller submergence (s) was studied in the range of 0.5d – 1.5d. the distance between the impellers (c3) varied in the range of 0.5d 2d. the variables ranges were chosen such that it include the optimum values for the operation of single impeller system(swapnil et al.2003) and this will permit to compare the results of this study with that of single impeller system. all these details are summarized in table 1. rate of gas induction (q) was measured for all these combinations. upper impeller flow meter transmission system d.c motor t h c2 c3 s d c1 disk turbine shrouded-disk/curved-blade impeller lower impeller section a a aeration wheel a a fig. 1. schematic diagram of the experimental diagram. alaa k. mohammed al-khwarizmi engineering journal, vol.4, no.4, pp1-8 (2008) 3 table 1. design details of gasinducing mechanically agitated contactor. diameter of vessel, t 0.5 m impeller diameter, d 0.15t, 0.25t, 0.35t baffle width 10% of vessel diameter. number of baffles 4 construction material stainless steel. geometry cylindrical with flat bottom lower impeller clearance from bottom c1 t/8, t/6, t/4 t = 0.5m submergence of upper impeller from the top liquid surface, s 0.5 d, 1d, 1.5d d = 0.15m impeller spacing, c3 0.5d, 1.5d, 2d d = 0.15m bottom bearing air cap air cap aeration wheel bottom bearing shaft bushing hollow shaft pulley ball bearing fermentor assembly upper impeller lower impeller shaft bushing vulcanite sleeve fig. 2. laboratory experimental fermentor with mechanical aerator. alaa k. mohammed al-khwarizmi engineering journal, vol.4, no.4, pp1-8 (2008) 4 3. results and discussion: 3.1. effect of impeller diameter: the effect of impeller diameter on the rate of gas induction was studied. the impeller diameter was varied from 0.15t – 3.5 t .the results are shown in figure 3. it can be seen that the rate of gas induction increases with an increase in the impeller diameter. it may be emphasized that the pumping effectiveness increases with an increase in the impeller diameter and hence larger inertia force generating at the edge of impeller which causing higher vacuum at the impeller tip and hence increasing the rate of gas induction. also it was noticed that larger impeller diameter show greater formation of bubbles (number), the size of bubbles is very fine, and the distribution of bubbles is uniform. however, on the other hand, it is very difficult to bubble the liquid when the impeller diameter is reduced to t/8. hence a decrease in the induction rate was observed. 0 5 10 15 20 25 30 35 40 0 100 200 300 400 500 600 700 800 impeller speed,n (rpm) r a te o f g a s i n d u s in g , q ( l /s ) d=0.35 t d=0.25 t d=0.15 t fig. 3. effect of impeller diameter and impeller speed on rate of gas induction (t=0.5 m, c1=1.5t, s=1.5 d, c3=2 d). 3.2. effect of submergence: this is a major parameter which affects the rate of gas induction. submergence is the liquid height above the upper impeller and is measured from the static liquid surface to the center line of the upper impeller. generally, it is known that the rate of gas induction decreases as the liquid submergence increases. experiments were carried out with submergence of the upper impeller was varied from 0.5d – 1.5d. the results are shown in figure 4. as pointed out earlier by saravanan et al. (1994), the critical impeller speed for gas induction increases with an increase in the liquid submergence. therefore, for the same rate of gas induction, a higher impeller speed is needed at a higher liquid submergence. it may be emphasized that increasing submergence (i.e the liquid height above the upper impeller) will led to increase the static liquid head at the impeller tip, the point which cause higher resistance for bubbles to liberate from impeller edge. there fore higher agitation speed is needed to react this effect and generating higher inertia force which assist the bubble to liberate from impeller edge. alaa k. mohammed al-khwarizmi engineering journal, vol.4, no.4, pp1-8 (2008) 5 0 5 10 15 20 25 30 35 40 0 50 100 150 200 250 300 350 400 450 impeller speed n (rpm) r a te o f in d u c ti o n , q ( l /s ) s= 0.5 d s=1.0 d s=1.5 d fig. 4. effect of submergence and impeller speed on rate of gas induction. (t=0.5 t, d=0.25 m, c1=1.5 t, c3=2d). 0 5 10 15 20 25 30 0 100 200 300 400 500 impeller speed, n (rpm) r a te o f g a s i n d u c ti o n , q ( l /s ) c3=0.5 d c3=1.5 d c3=2.0 d fig. 5. effect of impeller spacing (c3) on rate of gas induction. (t=0.5, d=0.15 m, c1=t/4, s=1.5 d). 3.3. effect of impeller spacing (impeller clearance): it is believed that the distance between the two impellers plays an important role in the gas induction process. spacing between the two impellers (c3) is measured between the two impeller center planes. effect of impeller spacing was extensively studied in a mechanically agitated contactor by zundelevich (1979) and joshi (1980) for two-turbine impellers. they have varied the impeller spacing over a wide range from 0.2d to 4d. in the present investigation, the distance between the two impellers was varied in the range of 0.5d-2d. the results are shown in figure 5. it alaa k. mohammed al-khwarizmi engineering journal, vol.4, no.4, pp1-8 (2008) 6 was observed that the rate of gas induction increases with a decrease in the impeller clearances. it may be emphasized that decreasing the distance between the impellers will led to generate a high agitation region near the suction impeller and hence causing higher vacuum which led to higher rate of gas induction. 0 5 10 15 20 25 30 35 40 45 0 100 200 300 400 500 600 700 800 impeller speed n (rpm) r a te o f g a s i n d u c ti o n , q (l /s ) c1= t/ 8 c1=t / 6 c1= t / 4 fig.6. effect of impeller bottom clearance on rate of gas induction. (t=0.5m, d=0.15m, s=1.5 d, c3=1.5 d). 3.4. effect of impeller bottom clearance: impeller off-bottom clearance c1 is measured between the lower impeller center plane and the tank bottom. the clearance of an impeller from tank base was varied from t/8 to t/4. the results are shown in figure 6. it was found that the rate of gas induction decreases with an increase in the clearance from bottom. it may be emphasized that decreasing the bottom clearance will cut the bubbles profile in the region between the tank bottom and the lower impeller that will led to increase the momentum of eddies near the surface impeller and hence increasing the vacuum near the impeller tip so higher gas rate induction is obtained. this finding is in agreement with that found with for simple impeller system (swapnil and joshi 2004). on the other hand very low clearance results in higher resistance for the flow, and hence a lower rate of gas induction is obtained that is because of higher friction between the motive fluid and the bottom of the tank which will generate higher resistance for liberation of bubbles from the impeller tip. 4. conclusions: 1. the rate of gas induction in the multipleimpeller system was found to be greater than that for the single impeller system. 2. also in the single-impeller system, the induced gas is not distributed throughout the vessel, but it takes only an upward path as soon as it is induced from the stator impeller region. this limitation is eliminated by using a dual-impeller system in which the induced gas (in the form of bubbles) is distributed throughout the vessel. 3. the submergence of the upper impeller was found to have a strong influence on the rate of gas induction. the rate of gas induction increased with a decrease in the submergence. 4. the rate of gas induction gas holdup decreased with an increase in the impeller spacing. 5. the rate of gas induction decreased with an increase in the clearance from the bottom. 6. for the same impeller type, the rate of gas induction increases with an increase in the stirrer diameter. alaa k. mohammed al-khwarizmi engineering journal, vol.4, no.4, pp1-8 (2008) 7 5. nomenclature: c1 upper impeller clearance form tank bottom (m). c2 lower impeller clearance from tank bottom (m). c3 impeller clearance (m), (center to center distance between two impellers). d impeller diameter (m). gimac gas-inducing mechanically agitated contactor. h height of liquid in vessel (m). n impeller rotational speed (rpm). q gas-induction rate (l/s). s submergence of upper impeller in clear liquid. t vessel diameter (m). 6. references: [1] swapnil, s.p.; deshmukh , n.a. and joshi, j.b.(2004)."masstransfer characteristics of surface aerators and gas – inducing impellers". ind. eng.chem.res. 43, 27652774. [2] shulka, v.b. and pandit, a.b. (2001). "scaleup of biotransformation process in stirred tank reactor using dual impeller bioreactor". biochemical engineering journal. 8, 19-20 [3] swapnil s.p.; patil and joshi j.b.(2003). "optimum design of multiple–impeller selfinducing system". ind. eng. chem res. 42, 1261-1265. [4] mishra, v. p.; joshi, j. b. (1993). flow generated by a disc turbine: part iii: effect of impeller diameter, impeller location and comparison with other radial and flow turbines. chem. eng. res. des., 71, 563570. [5] mundale, v. d.; joshi, j. b. (1995). optimization of impeller design for gas inducing type of agitated contactor. can. j. chem. eng., 73, 6-17. [6] joshi, j. b. (1980). modifications in the design of gas inducing impellers. chem. eng. commun., 5, 1 09-114. [7] joshi, j.b.; sharma, m. m. (1977). mass transfer and hydrodynamic characteristics of gas inducing type of agitated contactors. can. j. chem. eng., 65, 683-695. [8] raidoo, a. d.; raghavrao, k. s. m. s.; sawant, s. b.; joshi, j. b. (1987). improvements in gas inducing impeller design. chem. eng. commun., 54, 241-264. [9] saravanan, k.; mundale, v. d.; joshi, j. b. (1994). gas inducing type [10] mechanically agitated contactors. ind. eng. chem. res., 33, 22262241 [11] zlokarnik, m.; judat, h. (1967). tube and disk stirrers two efficient stirrers for the gassing of liquids. chem. ing. tech., 39, 1163-1168. [12] zundelevich, v. (1979). power consumption and gas capacity of self inducing turbo aerations. aiche j., 25, 763-773. 8-1، صفحة 4، العذد 4 مجلة الخىارزمي الهنذسية المجلذ عالء كريم محمذ (2008 ) 8 اداء المفاعالت الحيىية رات الخالطات المسدوجة الساحبة للهىاء عالء كريم محمذ حسنين علي حسين صفاء عبذ الرسىل جايعت بغذاد / يعهذ انهُذست انىساثٍت وانتقٍُاث االحٍائٍت نهذساساث انعهٍا الخالصة 60 و وسعت 0.5استخذو يفاعم رو قطش . تى قٍاط يعذل سحب انهىاء فً انًفاعالث انحٍىٌت راث انخالطاث انًضدوجت انساحبت نههىاء انخالط االعهى يٍ َىع : ٌتكىٌ َظاو انخهط فً انًفاعم يٍ خالطٍٍ يتساوٌٍٍ فً انقطش. استخذو انًاء كىسط سائم وانهىاء كىسط غاص. نتش (. disk turbine)وانخالط االسفم يٍ َىع انقشص انتىسبًٍُ (shrouded disk/curved-blade turbine) انشٌش االَبىبٍت انساحبت نههىاء دقٍقت ، َسبت قطش انخالط انى قطش انًفاعم ، / دوسة800 – 500سشعت دوساٌ انخالط بحذود :انًتغٍشاث انتً تى دساستها فً هزا انبحث هً . ، بعذ انخالط االسفم عٍ قعش انًفاعم ( clearance)، انًسافت بٍٍ انخالطٍٍ ( submergence)عًق انخالط االعهى عٍ سطح انسائم وجذ اٌ يعذل سحب انهىاء ٌضداد بضٌادة قطش انخالط وَقصاٌ عًق انخالط عٍ انسطح انعهىي نهسائم، بًٍُا ٌقم يعذل انسحب بضٌادة . انًسافت بٍٍ انخالطٍٍ وصٌادة انًسافت بٍٍ قعشانًفاعم وانخالط انسفهً this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 20, no. 4, december (2024), pp. 38-45 monitoring alkalinity and hardness during treatment of different water types shahad f. alrubaye1*, naseer a. al haboubi 2, hussein a. al-amili 3, aiman h. al-allaq4 and dina r. rzaij 5 1, 2 chemical engineering department, college of engineering, al nahrain university, baghdad, iraq khawarizmi college of engineering, university of baghdad, baghdad, -automated manufacturing engineering, al 3 iraq usa ,university (odu)department of mechanical and aerospace engineering, old dominion 4 lectrical engineering technical college, middle technical university, baghdad, iraqe5 shahad.fadhilma@gmail.com :mail-e ’scorresponding author* (received 17 april 2024; revised 8 july 2024; accepted 11 august 2024; published 1 december 2024) https://doi.org/10.22153/kej.2024.08.004 abstract alkalinity and hardness are crucial factors in water treatment procedures, such as electrocoagulation (ec) and traditional coagulation–flocculation. two types of water were employed in this study to investigate the use of ec: river water and discarded reverse osmosis system water. with bipolar and monopolar aluminum electrodes, continuous flow tests were conducted to evaluate the effects of different parameters on the variations in alkalinity and hardness versus time. the examined factors were flow rate (600 and 1,000 l/h) and number of electrodes (2 and 4). polarity reversal was also studied. the water passed through the plates in a zigzag pattern. results showed that the hardness under all operating conditions decreased with time, and alkalinity exhibited an oscillating behaviour. the ideal hardness removal for treating river and concentrated water was obtained using four plates with polarity reversal and a flow rate of 1,000 l/h, which were equal to 37.5% and 33.3%, respectively. keywords: alkalinity, hardness; electrocoagulation; tigris river; reverse osmosis rejected water; anode; cathode 1. introduction one of the most critical issues facing humanity today is ensuring that the majority of the world’s population has access to clean water. the demand for clean water is particularly high in third-world nations. rivers, canals, waterways and other bodies of water are continually contaminated by the discharge of industrial effluents, human activities and natural processes. therefore, cleaning and purifying water are important. one of the main problems in treating water is hardness removal. many processes, such as electrocoagulation, are used for hardness removal. electrocoagulation is an electrochemical method that effectively eliminates suspended solids, metals, colloidal particles, and other dissolved materials from water. the electrocoagulation method can be used to remove organic matter and nutrients in wastewater. a sacrificial anode is dissolved during the electrocoagulation process to create coagulants [1]. electrocoagulation is an innovative, practical, beneficial wastewater treatment technique. it is a complicated procedure that combines physics and chemistry [1]. water containing suspended particles and organic materials can be treated via electrocoagulation. flotation, coagulation and oxidation or reduction of polluting chemicals are involved in electrocoagulation [2]. electrocoagulation is an excellent method for treating organic and inorganic contaminants because it combines the advantages of flotation, electro-oxidation/reduction and coagulation– flocculation [3]. mailto:shahad.fadhilma@gmail.com https://doi.org/10.22153/kej.2024.08.004 shahad f. alrubaye al-khwarizmi engineering journal, vol. 20, no.4, p.p. 3845(2024) 39 an innovative, effective technique for the treatment of industrial wastewater is electrocoagulation–flocculation [3]. the electrocoagulation process has many advantages, such as flexibility, environmental compatibility, energy efficiency, cost effectiveness, automation and not requiring chemicals [4]. another ecologically beneficial technique is electrocoagulation, the effectiveness of which is determined by operational factors, such as initial ph, temperature, conductivity, time and current density. emerging approaches for removing contaminants from wastewater that rely on complicated methods are called electrocoagulation [5]. in this study, the variation in alkalinity and hardness versus time under different operating conditions was recorded, and treatment of reverse osmosis rejected water and tigris river water was performed. the polarity reversal effect was also studied. 2. experimental work 2.1 materials and methods an electrolytic cell was designed to perform the electrocoagulation procedure. the electrocoagulation arrangement utilised is shown in fig. 1. this figure shows the configuration and major components of the system used to treat river and concentrated water via the electrocoagulation method. to produce drinkable water, the system uses an electrochemical plastic reactor with a capacity of 120 l. the anode and cathode electrodes were made of aluminium plate electrodes with a length of 50 cm, width of 50 cm and thickness of 0.5 mm. as shown in fig. 2, the plates consisted of holes with 2.5 cm diameter spaced 5 cm apart. the electrodes were positioned vertically in the reactor. water passed through the holes on the plate, improving the mixing and dispersion of pollutants in the water and increasing the efficiency of the electrochemical process. the electrodes’ enhanced ability to contact the impurities accelerated the coagulation and flocculation processes because the holes formed alternate upward and downward flow channels. a 60to 50-min treatment period was chosen, and the plates were subjected to 36 v of applied voltage and 32 a of current. this study employed reverse and direct polarity modes. the polarity of the electrodes was switched every 10 min throughout the polarity reversal investigation to ensure that both electrodes worked for the same length of time as the cathode or anode and were nearly equally consumed. fig. 1 electrocoagulation reactor in the experiment. fig. 2. plates the electrode used. 2.2 water samples two types of water, namely, river and concentrated water, were used in this study. table 1 shows the operating variables for untreated water. shahad f. alrubaye al-khwarizmi engineering journal, vol. 20, no.4, p.p. 3845(2024) 40 table 1. operating variables for the experiments. water type number of plates flow rate l/h polarity type hardness removal% alkalinity change% conductivity s/cm2µ river 2 600 dp 20 4.3 890 river 2 600 rp 6.3 24.1 1423 river 4 600 rp 5.9 10.7 1151 river 4 600 dp 23.1 14 1009 river 2 1000 dp 9 31.5 1039 river 2 1000 rp 25 3.3 992 river 4 1000 dp 29.4 9.7 932.4 river 4 1000 rp 37.5 14.3 998 concentrated 2 600 dp 12.5 4.8 4062 concentrated 2 600 rp 5.3 100 4305 concentrated 4 600 rp 20 12.8 4287 concentrated 4 600 dp 16.7 4.3 6904.2 concentrated 2 1000 dp 11.1 6.9 3309 concentrated 2 1000 rp 21 25 4369 concentrated 4 1000 dp 15 4.8 3475 concentrated 4 1000 rp 33.3 12.5 4371 3. results and discussion the baseline concentrations of bicarbonate and carbonate ions were determined using the alkalinity of the water source being treated. alkalinity variations that occurred throughout the treatment were measured with reference to the original baseline. alkalinity variations can affect water’s ph stability, and hardness ions can create insoluble precipitates that interfere with the coagulation and flocculation processes’ capacity to work. alkalinity and hardness are often controlled factors in drinking water regulations because of their effects on water quality and possible health risks. the rate and level of alkalinity changes during electrocoagulation treatment can be influenced by operational factors, such as current density, electrode design, electrolyte concentration and treatment duration. the presence of dissolved minerals in water, especially calcium (ca) and magnesium (mg) ions, is the cause of alkalinity and hardness. alkalinity absorbs and neutralises acids, so it serves as a buffer against ph variations. by reacting with the bicarbonate and carbonate ions already present in the water to generate bicarbonate (hco3) and carbonate (co3 -2) ions, hardness ions, mainly calcium and magnesium, add to the alkalinity and overall buffering capacity of water. hardness and alkalinity are two different but related characteristics that affect water quality. elevated levels of alkalinity have the potential to influence the taste and odour of water and cause scaling problems in water systems. figs. 3 to 8 show the hardness and alkalinity variations with time. in the river water treatment process, under different operating conditions, a noticeable decrease was observed in the first 10 min, followed by a fluctuating trend in the subsequent period, as shown in figure 3a. as indicated in fig. 3b, alkalinity decreased in the first 15 min before increasing again. the hardness decrements versus time under both operating conditions exhibited almost the same trend, as shown in fig. 3. figs. 4a and 4b show that the alkalinity of river and concentrated water presented the same trend at a flow rate of 600 l/h flow in the two plate experiments without employing polarity reversal. the hardness trends presented in fig. 4 show that the hardness for both types of water decreased in the same manner versus time. the alkalinity value remained the same in the first 15 min, increased at 20 min and then increased again, as shown in fig. 5a. fig. 5b shows that alkalinity decreased in the first 10 min then increased in the next 15 min, followed by a decrease. fig. 5 shows the decrease in hardness for concentrated and river water. fig. 6 presents the reduction in alkalinity with time for river water, whose alkalinity profile is an almost mirror image of the profile for the alkalinity of concentrated water as it increases with time, as presented in fig. 6b. fig. 6 shows the hardness profiles of river and concentrated water. both profiles exhibit the same decreasing trend with time. alkalinity presented the same trend versus time for both types of water, as indicated in fig. 7. fig. 7 also presents the decrease in hardness versus time shahad f. alrubaye al-khwarizmi engineering journal, vol. 20, no.4, p.p. 3845(2024) 41 for both types of water. the decrease in hardness in both types of water exhibited the same behaviour. fig. 8 shows the alkalinity trends of river and concentrated water. both trends show a clear fluctuation in the alkalinity value versus time. fig. 8 also indicates that the decrements in hardness versus time for both types of water were similar. in terms of hardness, all the experiments showed a decrease in hardness versus time for both types of water. the increase in alkalinity can be attributed to the generation of an alkaline medium near the cathode. this study confirmed the alkalinity increase [8] [9]. as indicated in figs. 3 to 8, the decreasing alkalinity resulted from certain water-soluble substances, such as bicarbonate or carbonate ions, which may have reacted with the precipitates produced by electrocoagulation. others may have replaced these alkaline chemicals throughout the process, which might have reduced the overall alkalinity of the mixture. the decrease in alkalinity in this study followed the same behaviour as those in the studies of [10] [11]. electrocoagulation causes precipitation or coagulation, and it can help remove alkaline impurities or chemicals that encourage alkalinity. the alkalinity of treated water may be lost because of this removal. the decrease in alkalinity in this study is similar to that in the work of raju et al. [10] and saiba et al. [11]. meanwhile, no change in alkalinity occurs in some situations according to franco, who stated that the ec procedure has no noticeable effect on water’s alkalinity; this effect is essential because some degree of alkalinity is required to avoid sudden ph fluctuations, as mentioned by franco et al. [12]. the same alkalinity trend was reported in previous studies [13] [14][15]. the decrease in alkalinity could also be attributed to the generation of hydroxide ions (oh) at the cathode as a consequence of water reduction processes when bicarbonate ions (hco-3) and/or carbonate ions (co3 -2) are consumed. if hydroxide ions are consumed as a result of acidic byproducts generated by oxidation processes at the anode, alkalinity may also decrease. alkalinity may increase as a result of electrocoagulation procedures in some circumstances. this increment may occur if the cathode produces hydroxide ions that raise the solution’s alkalinity. furthermore, if some species are originally present in the water, their precipitation as hydroxide or carbonate salts may increase alkalinity. protons (h+) are consumed and hydroxide ions (oh-) are produced at the cathode as a result of water reduction processes. proton consumption can raise ph and alkalinity. oxidation processes can produce acidic byproducts, such as hydrogen ions (h+), at the anode. ph and alkalinity may decrease as a result. 5 10 15 20 25 30 35 100 110 120 130 140 150 160 170 180 190 alkalinity a lk a li n it y ( a s c a c o 3 ) time (min.) 5 10 15 20 25 30 35 300 310 320 330 340 350 360 370 380 390 alkalinity a lk a li n it y ( a s c a c o 3 ) time (min.) a b 5 10 15 20 25 30 35 80 85 90 95 100 105 110 hardness h a rd n e s s time (min.) 5 10 15 20 25 30 35 155 160 165 170 175 180 185 190 195 200 hardness h a rd n e s s time (min.) a b fig. 3. alkalinity and hardness versus time. a) river water continuous process employing two plates, 600 l/h, and absence of polarity reversal. b) continuous process of treating concentrated water at a flow rate of 600 l/h and with the absence of polarity reversal by using two plates. shahad f. alrubaye al-khwarizmi engineering journal, vol. 20, no.4, p.p. 3845(2024) 42 5 10 15 20 25 30 35 184 186 188 190 192 194 196 alkalinity a lk a lin it y ( a s c a c o 3 ) time (min.) 5 10 15 20 25 30 35 155 160 165 170 175 alkalinity a lk a lin it y ( a s c a c o 3 ) time (min.) a b 5 10 15 20 25 30 35 100 110 120 130 140 150 160 hardnessh a rd n e s s time (min.) 5 10 15 20 25 30 35 75 80 85 90 95 hardnessh a rd n e s s time (min.) a b fig. 4. alkalinity and hardness versus time. a) continuous process with concentrated water, absence of polarity reversal and use of four plates at 600 l/h. b) river water continuous process employing four plates, 600 l/h, with polarity reversal. 5 10 15 20 25 150 155 160 165 170 175 180 alkalinity a lk a lin it y ( a s c a c o 3 ) time (min.) 5 10 15 20 25 400 420 440 460 480 500 alkalinity a lk a lin it y ( a s c a c o 3 ) time (min.) a b 5 10 15 20 25 640 660 680 700 720 740 760 780 800 hardness h a rd n e s s time (min.) a b 5 10 15 20 25 145 150 155 160 165 170 175 180 185 190 hardness h a rd n e s s time (min.) fig. 5. alkalinity and hardness versus time. a) river water continuous process with 600 l/h flow rate and polarity reversal by using two plates. b) concentrated water continuous process with polarity reversal and 600 l/h by using two plates. 5 10 15 20 25 120 130 140 150 160 alkalinity a lk a lin it y ( a s c a c o 3 ) time (min.) a b 5 10 15 20 25 355 360 365 370 375 380 385 390 395 400 alkalinity a lk a lin it y ( a s c a c o 3 ) time (min.) 5 10 15 20 25 70 71 72 73 74 75 hardnessh a rd n e s s time (min.) a b 5 10 15 20 25 60 70 80 90 100 110 hardnessh a rd n e s s time (min.) reversal 000 l/h with polarity ,1 at water continuous processiver r )atime. versus alkalinity and hardness .fig. 6 two with polarity reversal by using 000 l/h ,1at water continuous process concentrated )two plates. bby using .plates shahad f. alrubaye al-khwarizmi engineering journal, vol. 20, no.4, p.p. 3845(2024) 43 10 15 20 25 30 35 40 370 380 390 400 410 420 430 440 450 460 alkalinity a lk a lin it y ( a s c a c o 3 ) time (min.) 10 15 20 25 30 35 40 150 152 154 156 158 160 162 alkalinity a lk a lin it y ( a s c a c o 3 ) time (min.) a b 10 15 20 25 30 35 40 140 160 180 200 220 240 260 280 300 hardness h a rd n e s s time (min.) 10 15 20 25 30 35 40 50 52 54 56 58 60 hardnessh a rd n e s s time (min.) a b fig. 7. alkalinity and hardness versus time. a) continuous process with concentrated water and the absence of polarity reversal by using two plates and 1,000 l/h flow rate. b) river water continuous process at 1,000 l/h flow rate and with the absence of polarity reversal by using two plates. 0 10 20 30 40 50 130 135 140 145 150 155 160 alkalinity a lk a li n it y ( a s c a c o 3 ) time (min.) a b 0 10 20 30 40 50 400 410 420 430 440 450 460 alkalinity a lk a li n it y ( a s c a c o 3 ) time (min.) 0 10 20 30 40 50 60 65 70 75 80 85 90 hardnessh a rd n e s s time (min.) a b 0 10 20 30 40 50 120 140 160 180 200 220 240 260 280 300 320 hardness h a rd n e s s time (min.) fig. 8. alkalinity and hardness versus time. a) river water continuous process using two plates, 600 l/h flow rate and absence of polarity reversal. b) continuous process for concentrated water using two plates, 600 l/h flow rate and absence of polarity reversal. 4. conclusion in water treatment procedures, such as electrocoagulation and conventional coagulation– flocculation, alkalinity and hardness are important factors to consider. hardness ions can produce insoluble precipitates that reduce treatment efficacy, and alkalinity affects ph stability. drinking water standards control them because of their effects on health and water quality. bicarbonate and carbonate ions are the baseline for alkalinity, and treatment differences are evaluated on the basis of this baseline. alkalinity and hardness are influenced by calcium and magnesium ions, which also affect the quality and buffering power of water. high hardness levels prevent soap from working well and promote the development of scale, and high alkalinity levels affect taste, odour and scaling. non-polarity-reversing hardness data exhibit consistent declines in contrast to reverse polarity data fluctuations. acknowledgements the baghdad soft drinks company’s general manager, engineer hayder al-bassam, and operations manager, engineer sattar hassan, have our deepest gratitude for their support for the research and their perceptive remarks that helped the authors realise the study’s potential for realworld applications. shahad f. alrubaye al-khwarizmi engineering journal, vol. 20, no.4, p.p. 3845(2024) 44 references [1] s. elia, m. stylianou, and a. agapiou, “aroma characterization of raw and electrochemically treated goat whey wastewater,” sustain chem pharm, vol. 27, jun. 2022, doi: 10.1016/j.scp.2022.100640. 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[11] a. saiba, s. kourdali, b. ghernaout, and d. ghernaout, “in desalination, from 1987 to 2009, the birth of a new seawater pretreatment process: electrocoagulation-an overview,” desalination and water treatment, vol. 16, no. 1–3. taylor and francis inc., pp. 201–217, 2010. doi: 10.5004/dwt.2010.1094. [12] d. franco, j. lee, s. arbelaez, n. cohen, and j. y. kim, “removal of phosphate from surface and wastewater via electrocoagulation,” ecol eng, vol. 108, pp. 589–596, nov. 2017, doi: 10.1016/j.ecoleng.2017.07.031. [13] d. r. ryan, p. j. mcnamara, and b. k. mayer, “iron-electrocoagulation as a disinfection byproduct control strategy for drinking water treatment,” environ sci (camb), vol. 6, no. 4, pp. 1116–1124, apr. 2020, doi: 10.1039/d0ew00106f. [14] c. ucar, m. b. baskan, and a. pala, “arsenic removal from drinking water by electrocoagulation using iron electrodes,” korean journal of chemical engineering, vol. 30, no. 10, pp. 1889–1895, jun. 2013, doi: 10.1007/s11814-013-0128-2. [15] b. zhu, d. a. clifford, and s. chellam, “comparison of electrocoagulation and chemical coagulation pretreatment for enhanced virus removal using microfiltration membranes,” water res, vol. 39, no. 13, pp. 3098–3108, 2005, doi: 10.1016/j.watres.2005.05.020. (2024) 38-45، صفحة 4، العدد20مجلة الخوارزمي الهندسية المجلد شهد فاضل الربيعي 45 تغييرات القلوية والعسرة في انظمة التخثير الكهربائيمراقبة ، 3حسين علي العاملي ،2نصير عبود الحبوبي ، *1شهد فاضل الربيعي 5دينا رحيم رزيج ،4ايمن هادي العالق ، بغداد، العراقجامعة النهرين، كلية الهندسة ،قسم الهندسة الكيمياوية 1،2 ، بغداد، العراقجامعة بغداد ،كلية الهندسة الخوارزمي ،التصنيع المؤتمت هنسة قسم 3 الواليات المتحدة االمريكية ،جامعة دومنيون 4 ، بغداد، العراقلجامعة التقنية الوسطىا، الكلية التقنية الهندسية الكهربائية 5 shahad.fadhilma@gmail.com*البريد االلكتروني: المستخلص تم .(: مياه النهر والمياه المرفوضة من منظومة التناضح العكسي ecتم استخدام نوعين من المياه في هذه الدراسة لدراسة استخدام التخثير الكهربائي ) لقلوية والعسرة مع استخدام أقطاب األلومنيوم ثنائية القطب وأحادية القطب، تم إجراء اختبارات الجريان المستمر لتقييم تأثيرات عوامل مختلفة على تغير ا تم . دراسة عكس القطبية الكهربائيةكما تمت (. 2,4)وعدد األقطاب الكهربائية ( ساعة /لتر 600,1000)الزمن. العوامل التي تم دراستها هي معدل الجريان ( في مفاعل بالستيكي شفاف يحتوي على ثقوب داخل ecإجراء التجارب الخاصة بالبحث باستخدام مفاعل مبتكر يقوم بإجراء عملية التخثير الكهربائي ) (. يكون جريان المياه عبر الصفائحthلة العسرة الكلية )األقطاب الكهربائية المصنوعة من األلومنيوم والتي تم استخدامها في تجارب الجريان المستمر إلزا أظهرت النتائج أن قيم العسرة الكلية انخفضت في جميع ظروف التشغيل المختلفة مع مرور الوقت. بينما القلوية اظهرت سلوكا . بشكل متعرج (االقطاب) متذبذبا. mailto:shahad.fadhilma@gmail.com monitoring alkalinity and hardness during treatment of different water types shahad f. alrubaye1*, naseer a. al haboubi 2, hussein a. al-amili 3, aiman h. al-allaq4 and dina r. rzaij 5 1, 2 chemical engineering department, college of engineering, al nahrain university, baghdad, iraq 3 automated manufacturing engineering, al-khawarizmi college of engineering, university of baghdad, baghdad, iraq 4department of mechanical and aerospace engineering, old dominion university (odu), usa 5electrical engineering technical college, middle technical university, baghdad, iraq * corresponding author’s e-mail: shahad.fadhilma@gmail.com https://doi.org/10.22153/kej.2024.08.004 abstract alkalinity and hardness are crucial factors in water treatment procedures, such as electrocoagulation (ec) and traditional coagulation–flocculation. two types of water were employed in this study to investigate the use of ec: river water and discarded... keywords: alkalinity, hardness; electrocoagulation; tigris river; reverse osmosis rejected water; anode; cathode 1. introduction one of the most critical issues facing humanity today is ensuring that the majority of the world’s population has access to clean water. the demand for clean water is particularly high in third-world nations. rivers, canals, waterways and other bodie... electrocoagulation is an electrochemical method that effectively eliminates suspended solids, metals, colloidal particles, and other dissolved materials from water. the electrocoagulation method can be used to remove organic matter and nutrients in wa... electrocoagulation is an innovative, practical, beneficial wastewater treatment technique. it is a complicated procedure that combines physics and chemistry [1]. water containing suspended particles and organic materials can be treated via electrocoag... an innovative, effective technique for the treatment of industrial wastewater is electrocoagulation–flocculation [3]. the electrocoagulation process has many advantages, such as flexibility, environmental compatibility, energy efficiency, cost effectiveness, automation and not requiring chemicals [4]. another ecologically beneficial technique is electrocoagulation, t... in this study, the variation in alkalinity and hardness versus time under different operating conditions was recorded, and treatment of reverse osmosis rejected water and tigris river water was performed. the polarity reversal effect was also studied. 2. experimental work 2.1 materials and methods an electrolytic cell was designed to perform the electrocoagulation procedure. the electrocoagulation arrangement utilised is shown in fig. 1. this figure shows the configuration and major components of the system used to treat river and concentrated... fig. 1 electrocoagulation reactor in the experiment. fig. 2. plates the electrode used. 2.2 water samples two types of water, namely, river and concentrated water, were used in this study. table 1 shows the operating variables for untreated water. the baseline concentrations of bicarbonate and carbonate ions were determined using the alkalinity of the water source being treated. alkalinity variations that occurred throughout the treatment were measured with reference to the original baseline. a... alkalinity and hardness are often controlled factors in drinking water regulations because of their effects on water quality and possible health risks. the rate and level of alkalinity changes during electrocoagulation treatment can be influenced by operational factors, such as current density, electrode design, electrolyte concentration and treatment duration. the presence of dissolved minerals in w... alkalinity absorbs and neutralises acids, so it serves as a buffer against ph variations. by reacting with the bicarbonate and carbonate ions already present in the water to generate bicarbonate (hco-3) and carbonate (co3-2) ions, hardness ions, mainl... in the river water treatment process, under different operating conditions, a noticeable decrease was observed in the first 10 min, followed by a fluctuating trend in the subsequent period, as shown in figure 3a. as indicated in fig. 3b, alkalinity de... figs. 4a and 4b show that the alkalinity of river and concentrated water presented the same trend at a flow rate of 600 l/h flow in the two plate experiments without employing polarity reversal. the hardness trends presented in fig. 4 show that the ha... the alkalinity value remained the same in the first 15 min, increased at 20 min and then increased again, as shown in fig. 5a. fig. 5b shows that alkalinity decreased in the first 10 min then increased in the next 15 min, followed by a decrease. fig. ... fig. 6 presents the reduction in alkalinity with time for river water, whose alkalinity profile is an almost mirror image of the profile for the alkalinity of concentrated water as it increases with time, as presented in fig. 6b. fig. 6 shows the har... alkalinity presented the same trend versus time for both types of water, as indicated in fig. 7. fig. 7 also presents the decrease in hardness versus time for both types of water. the decrease in hardness in both types of water exhibited the same beh... fig. 8 shows the alkalinity trends of river and concentrated water. both trends show a clear fluctuation in the alkalinity value versus time. fig. 8 also indicates that the decrements in hardness versus time for both types of water were similar. in te... the increase in alkalinity can be attributed to the generation of an alkaline medium near the cathode. this study confirmed the alkalinity increase [8] [9]. as indicated in figs. 3 to 8, the decreasing alkalinity resulted from certain water-soluble substances, such as bicarbonate or carbonate ions, which may have reacted with the precipitates produced by electrocoagulation. others may have replaced these ... electrocoagulation causes precipitation or coagulation, and it can help remove alkaline impurities or chemicals that encourage alkalinity. the alkalinity of treated water may be lost because of this removal. the decrease in alkalinity in this study is... meanwhile, no change in alkalinity occurs in some situations according to franco, who stated that the ec procedure has no noticeable effect on water’s alkalinity; this effect is essential because some degree of alkalinity is required to avoid sudden p... the decrease in alkalinity could also be attributed to the generation of hydroxide ions (oh) at the cathode as a consequence of water reduction processes when bicarbonate ions (hco-3) and/or carbonate ions (co3-2) are consumed. if hydroxide ions are c... alkalinity may increase as a result of electrocoagulation procedures in some circumstances. this increment may occur if the cathode produces hydroxide ions that raise the solution’s alkalinity. furthermore, if some species are originally present in th... oxidation processes can produce acidic byproducts, such as hydrogen ions (h+), at the anode. ph and alkalinity may decrease as a result. fig. 3. alkalinity and hardness versus time. a) river water continuous process employing two plates, 600 l/h, and absence of polarity reversal. b) continuous process of treating concentrated water at a flow rate of 600 l/h and with the absence of pola... fig. 4. alkalinity and hardness versus time. a) continuous process with concentrated water, absence of polarity reversal and use of four plates at 600 l/h. b) river water continuous process employing four plates, 600 l/h, with polarity reversal. fig. 5. alkalinity and hardness versus time. a) river water continuous process with 600 l/h flow rate and polarity reversal by using two plates. b) concentrated water continuous process with polarity reversal and 600 l/h by using two plates. fig. 6. alkalinity and hardness versus time. a) river water continuous process at 1,000 l/h with polarity reversal by using two plates. b) concentrated water continuous process at 1,000 l/h with polarity reversal by using two plates. fig. 7. alkalinity and hardness versus time. a) continuous process with concentrated water and the absence of polarity reversal by using two plates and 1,000 l/h flow rate. b) river water continuous process at 1,000 l/h flow rate and with the absence ... fig. 8. alkalinity and hardness versus time. a) river water continuous process using two plates, 600 l/h flow rate and absence of polarity reversal. b) continuous process for concentrated water using two plates, 600 l/h flow rate and absence of polari... 4. conclusion in water treatment procedures, such as electrocoagulation and conventional coagulation–flocculation, alkalinity and hardness are important factors to consider. hardness ions can produce insoluble precipitates that reduce treatment efficacy, and alkal... acknowledgements the baghdad soft drinks company’s general manager, engineer hayder al-bassam, and operations manager, engineer sattar hassan, have our deepest gratitude for their support for the research and their perceptive remarks that helped the authors realise th... [1] s. elia, m. stylianou, and a. agapiou, “aroma characterization of raw and electrochemically treated goat whey wastewater,” sustain chem pharm, vol. 27, jun. 2022, doi: 10.1016/j.scp.2022.100640. [2] v. m. garcía-orozco, g. roa-morales, i. linares-hernández, i. j. serrano-jimenes, m. a. salgado-catarino, and r. natividad, “electrocoagulation of a chocolate industry wastewater in a downflow column electrochemical reactor,” journal of water proc... [3] t. shahriari, a. r. karbassi, and m. reyhani, “treatment of oil refinery wastewater by electrocoagulation–flocculation (case study: shazand oil refinery of arak),” international journal of environmental science and technology, vol. 16, no. 8, pp. ... [4] r. niazmand, m. jahani, and s. kalantarian, “treatment of olive processing wastewater by electrocoagulation: an effectiveness and economic assessment,” j environ manage, vol. 248, oct. 2019, doi: 10.1016/j.jenvman.2019.109262. [5] gunarif taib, wenny surya murtius, risa meutia fiana, and wahyunanto agung nugroho, “systematic literature electrocoagulation for wastewater treatment: mini-review,” world journal of advanced research and reviews, vol. 18, no. 2, pp. 690–699, may ... [6] l. t. n. maleiva, p. w. nugraheni, f. ramadhan, l. s. a. putra, and e. kusumawardhani, “treatment of dug well water in kubu raya, west kalimantan, with electrocoagulation,” iop conf ser earth environ sci, vol. 1228, no. 1, p. 012013, aug. 2023, do... [7] r. danial, l. chuah abdullah, and s. sobri, “potential of copper electrodes in electrocoagulation process for glyphosate herbicide removal.” [8] j. n. hakizimana, n. najid, b. gourich, c. vial, y. stiriba, and j. naja, “hybrid electrocoagulation/electroflotation/electrodisinfection process as a pretreatment for seawater desalination,” chem eng sci, vol. 170, pp. 530–541, oct. 2017, doi: 10... [9] a. dubey and a. tewari, “performance of aluminium electrode in defluoridation of water during electrocoagulation,” materials focus, vol. 7, no. 5, pp. 657–661, oct. 2018, doi: 10.1166/mat.2018.1560. [10] g. b. raju, m. t. karuppiah, s. s. latha, s. parvathy, and s. prabhakar, “treatment of wastewater from synthetic textile industry by electrocoagulation-electrooxidation,” chemical engineering journal, vol. 144, no. 1, pp. 51–58, oct. 2008, doi: 1... [11] a. saiba, s. kourdali, b. ghernaout, and d. ghernaout, “in desalination, from 1987 to 2009, the birth of a new seawater pretreatment process: electrocoagulation-an overview,” desalination and water treatment, vol. 16, no. 1–3. taylor and francis ... [12] d. franco, j. lee, s. arbelaez, n. cohen, and j. y. kim, “removal of phosphate from surface and wastewater via electrocoagulation,” ecol eng, vol. 108, pp. 589–596, nov. 2017, doi: 10.1016/j.ecoleng.2017.07.031. [13] d. r. ryan, p. j. mcnamara, and b. k. mayer, “iron-electrocoagulation as a disinfection byproduct control strategy for drinking water treatment,” environ sci (camb), vol. 6, no. 4, pp. 1116–1124, apr. 2020, doi: 10.1039/d0ew00106f. [14] c. ucar, m. b. baskan, and a. pala, “arsenic removal from drinking water by electrocoagulation using iron electrodes,” korean journal of chemical engineering, vol. 30, no. 10, pp. 1889–1895, jun. 2013, doi: 10.1007/s11814-013-0128-2. [15] b. zhu, d. a. clifford, and s. chellam, “comparison of electrocoagulation and chemical coagulation pretreatment for enhanced virus removal using microfiltration membranes,” water res, vol. 39, no. 13, pp. 3098–3108, 2005, doi: 10.1016/j.watres.20... مراقبة تغييرات القلوية والعسرة في انظمة التخثير الكهربائي شهد فاضل الربيعي1*، نصير عبود الحبوبي2، حسين علي العاملي3، ايمن هادي العلاق4، دينا رحيم رزيج5 1،2 قسم الهندسة الكيمياوية، كلية الهندسة، جامعة النهرين، بغداد، العراق 3 قسم هنسة التصنيع المؤتمت، كلية الهندسة الخوارزمي، جامعة بغداد، بغداد، العراق 4 جامعة دومنيون، الولايات المتحدة الامريكية 5 الكلية التقنية الهندسية الكهربائية، الجامعة التقنية الوسطى، بغداد، العراق *البريد الالكتروني: shahad.fadhilma@gmail.com المستخلص تم استخدام نوعين من المياه في هذه الدراسة لدراسة استخدام التخثير الكهربائي (ec): مياه النهر والمياه المرفوضة من منظومة التناضح العكسي .تم استخدام أقطاب الألومنيوم ثنائية القطب وأحادية القطب، تم إجراء اختبارات الجريان المستمر لتقييم تأثيرات عوامل مختلف... 85 al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 4, no. 3, pp 85-97 (2008) studying the effect of volume fraction of glass fibers on the thermal conductivity of the polymer composite materials mohammed sellab hamza material engineering departement /university of technolog (received 11 march 2008; accepted 18 june 2008) abstract in this study the effect of fiber volume fraction of the glass fiber on the thermal conductivity of the polymer composite material was studied. different fiber volume fraction of glass fibers were used (3%, 6%, 9%, 12%, and 15%). specimens were made from polyester which reinforced with glass fibers .the fibers had two arrangements according to the direction of the thermal flow. in the first arrangement the fibers were parallel to the direction of the thermal flow, while the second arrangement was perpendicular; lee's disk method was used for testing the specimens. the experimental results proved that the values of the thermal conductivity of the specimens was higher when the fibers arranged in parallel direction than that when the fibers arranged in the perpendicular direction. the percentage of increasing of experimental thermal conductivity was 96.91% for parallel arrangement and 13.33% for perpendicular arrangement comparison with its original value before the using of glass fibers. also the experimental results indicated that the thermal conductivity increases with the increasing of the fiber volume fraction. minimum value was (0.172 w/m.c) for perpendicular arrangement at fiber volume fraction 3% and maximum value was (0.327 w/m.c) for parallel arrangement at fiber volume fraction 15%. keywords: polymer, glass fibers, thermal conductivity. introduction thermal conductivity is a phenomena of the heat transfer phenomenon, so the thermal conductivity is defined as the transfer of heat from area of high temperature to that of low temperature. the rate of heat transfer depends upon the temperature gradient and the components of materials. the direction of heat transfer will be opposite to the temperature gradient since the net energy transfer will be from high temperature to low. the thermal conductivity of solids materials is greater than that of liquids and gases materials. for solid materials it is four times than that of gases material. this is due to the difference between the voids of the two materials. gases transfer heat by direct collisions between molecules, and as would be expected, their thermal conductivity is low compared to most solids since they are dilute media. metals have better thermal conductivity than non-metals because the same mobile electrons which participate in electrical conduction also take part in the transfer of heat. non-metallic solids transfer heat by lattice vibrations so that there is no net motion of the media as the energy propagates through. such heat transfer is often described in terms of "phonons", quanta of lattice vibrations [1]. the free electrons are responsible for the transferring the thermal power through the conduct materials, while for the insulating materials such as polymers, the photons is responsible for this phenomena [1]. zhan-sheng et. al. [1] used the finite element formulation of transient heat transfer problem for polymeric matrix composite materials from the heat transfer differential equations to study the experimental and numerical temperature distribution of thick polymeric matrix laminates during an autoclaves vacuum bag process. murthy et. al. [2] studied the distribution of the temperature and the analysis of thermal stresses across the composite thick plates by using two-dimensional finite and physical model element model for this analysis in both mohammed sellab hamza al-khwarizmi engineering journal, vol. 4, no. 3, pp 85-97 (2008) 86 longitudinal and transverse directions for three different filter materials with epoxy as matrix material. rondeaux et al. [3] improved a specific thermal conductivity measurement facility for solid materials at low temperature where the thermal conductivity measurements on pre-impregnated fibers glass epoxy composite are tested in the range of temperature (4.2 to 14 k) in order to extract the thermal boundary resistance for different thicknesses. raimund [4] studied the analysis of temperature fields for hybrid and conventional composite structures by using the two-dimensional and threedimensional finite element formulations for the analysis of temperature fields for hybrid and conventional composite structures. khalaf [5] studied the thermal conductivity and the mechanical and physical properties for unsaturated polyester reinforced by fiber glass and nylon fiber composites and found that the thermal conductivity decrease with increase of nylon fiber layers and also decreases with the increase the volume fraction, for the samples of laminar reinforced system. pilling et. al. [6] studied the effect of orientation of fiber and the fiber volume fraction on the thermal conductivity of composite materials reinforced with fiber of carbon. they proved that the thermal conductivity increases with increasing of the fiber volume fraction and were higher in the parallel arrangement of the fibers than that for perpendicular arrangement. elie [7] studied the thermal conductivity and mechanical properties for polymer composite material reinforced by aluminum and aluminum oxide particles and found that the thermal conductivity increased with the increase of the weight fraction of metallic and ceramic particles and reach a maximum value at a weight fraction of (20 %) and for the composite material reinforced with (al) was ( 0.407 w/m.  c) and for the composite material reinforced with (al2o3) was (0.319 w/m.  c) at the same weight fraction. james and harrison [8] calculated heat flow and distribution of temperature by using the finite difference method in composite materials made from anisotropic materials by taking in to account the local re-orientation of the grid and the temperature distribution. heat flow was derived for a composite material made from two materials with anisotropic thermal conductivities the aim of this study is to study the effect of fiber volume fraction and their direction (parallel or perpendicular to heat flow) of the reinforcement material (glass fibers) on the thermal conductivity. the specimens were made from polyester reinforced with five different volume fraction of glass fiber (3%, 6%, 9%, 12% and 15%). the reinforcement material (glass fiber) was arranged in two methods. in the first method the glass fibers was aligned in the parallel direction to the heat flow while in the second method the glass fibers was aligned perpendicular to its. theoretical analysis the volume fraction of matrix and reinforcement material is calculated from the following equations [9]. avolume fraction of matrix ...(1) bvolume fraction of glass fibers ...(2) the electric power pass through the heating coil is calculated by the following formula. p=v.i …(3) the transferring of the thermal energy is carried out in two ways. these are: 1the vibrating waves of the lattice. 2the movement of the free electrons. the thermal conductivity is defined by the following formula [9]: q= -k dt/dx ...(4) the equation (4) used only for steady state of thermal flow and when the thermal flux is fixed and does not change with time. the minus sign means that the transfer of heat is starting from hot part to the cold part. the direction of heat transfer will be opposite to the temperature gradient since the net energy transfer will be from high temperature to low. this direction of maximum heat transfer will be perpendicular to the equal-temperature surfaces surrounding a source of heat. the theoretical thermal conductivity is calculating by the following equation [9, 10]. ...(5) the heat loss (e) through the unit time (second) and through the area (m 2 ) is calculated by the following formula [11]: ...(6) the theoretical thermal conductivity of composite materials is estimated from the following equations [12, 13, 14]: 1-heat flow is parallel to the glass fibers: % c m mv    % c f fv                           2 t s d r 1 1 t s d 2 1 1 d r 2 1 te s d 1 t 2 t k            3 t 3 d 2 t 2 d 2 t 1 t s d 2 1 1 t 1 derπ2 3 t 1 te2rπvi mohammed sellab hamza al-khwarizmi engineering journal, vol. 4, no. 3, pp 85-97 (2008) 87 …(7) 2heat flow is perpendicular to the glass fibers: ....(8) experimental work the samples were manufactured from unsaturated polyester (thermosets) which reinforced with different values of fiber volume fraction of fiber glass. the hardener type of mekp (methyl ethyl keto peroxide ) was added by 2% of resin and the cobalt octeate also added by 0.5% to speed up the reaction and increases the solidification of the samples. in this studying, the lee's disk method is used for measuring the thermal conductivity. figure (1) shows the electric circuit which used for this method. figure (2) shows the instrument used for this method. the instrument is consist of heating coil and three brass disks (1, 2, 3). the specimen was fixed between brass disks (1,2) while the heating coil was fixed between brass disks (2,3) as shown in figure (1). the cylindrical specimens were made from polyester matrix material which reinforced by glass fibers, the geometry of the specimens are r =0.02m, ds =0.007m. the first group of specimens reinforced with the glass fibers parallel to the direction of thermal flow and the second group of the specimens are perpendicular to the thermal flow. the experimental temperature t1, t2, and t3 were measured by means of lee`s disk method. the applied voltage across the terminal of the heating coil is (6 volt) and the current is (0.2 amper). the heating coil was used to heat the brass disks (1, 2, 3) and heat transfer across the specimen from the bass disk (2) to brass disk (1).the temperatures of all disks increases gradually and the temperatures recorded every (5 minutes) by using thermometers until reach the equilibrium temperature of all disks (i.e. t2=t3). the losses in heat (e) was calculated from equation (6).the thermal conductivity (k) was calculated from equation (5) by using the experimental temperatures (t1, t2, t3) and the dimension of specimen (r,ds). fig.1. thermal conductivity measurment. fig. 2. test apparatus with specimens test. m v m k f v f k c1 k  f v m k m v f k m k f k c2 k    3 1 s 2 h t1 t2 t3 a t2 t1 heater specimen t3 brass disks mohammed sellab hamza al-khwarizmi engineering journal, vol. 4, no. 3, pp 85-97 (2008) 88 results and discussions the properties of the unsaturated polyester and glass fibers are presented in table (1). table (2) illustrates the theoretical thermal conductivity of composite material for parallel and perpendicular arrangement and the difference between them. this table indicated that the difference increase with the increasing the fiber volume fracture and this leads to that the thermal conductivity of composite materials improve with the addition of glass fibers. tables (3, 4) show some properties of the manufactured composite specimens at different fiber volume fraction for both directions parallel and perpendicular respectively. these tables show that the properties of manufactured specimens were improved and increase with the increasing of the fiber volume fraction of glass fibers. figure (3) shows the relationship between the experimental temperature of the wall surface (t1and t2) of the tested specimens and the time for the unsaturated polyester. it is clear from these figures that the experimental temperatures of wall surface (t2 and t3) increase with time until it reach the equilibrium temperature (t2=t3). table 1 properties of unsaturated polyester and glass fibers[12]. percent elongation % poisson's ratio thermal conductivity (w/m. o c) tensile stress (mpa.) modulus of elasticity (gpa ) density (g/cm 3 ) material type 4.3 0.22 1.3 3450 72.5 2.58 glass fiber > 2.6 0.33 0.17 70.3-103 2.06-4.41 1.04-1.46 unsaturated polyester table 2 theoretical thermal conductivity for the parallel and the perpendicular arrangement composite materials. fiber volume fraction % theoretical thermal conductivity (kc) (w/m. o c) the difference between parallel and perpendicular arrangement parallel arrangement perpendicular arrangement 0 0.170 0.170 0.000 3 0.204 0.175 0.029 6 0.238 0.179 0.059 9 0.272 0.184 0.088 12 0.306 0.190 0.116 15 0.340 0.195 0.145 table 3 properties of the manufactured composite specimens when the fiber are arranged in the parallel direction to the heat flow. properties fiber volume fraction 3% 6% 9% 12% 15% ρ(g/cm3 ) 1.086 1.32 1.179 1.225 1.271 kx(w/m-co) 0.175 0.179 0.184 0.190 0.195 ky(w/m-co) 0.175 0.179 0.184 0.190 0.195 kz(w/m-co) 0.204 0.238 0.272 0.306 0.340 table 4 properties of the manufactured composite specimens when the fiber are arranged in the perpendicular direction to the heat flow. properties fiber volume fraction 3% 6% 9% 12% 15% ρ (g/cm3 ) 1.086 1.32 1.179 1.225 1.271 kx(w/m-co) 0.204 0.238 0.272 0.306 0.340 ky(w/m-co) 0.204 0.238 0.272 0.306 0.340 kz(w/m-co) 0.175 0.179 0.184 0.190 0.195 mohammed sellab hamza al-khwarizmi engineering journal, vol. 4, no. 3, pp 85-97 (2008) 89 fig.3. relationship between the experimental wall surface temperatures (t1and t2) of the tested specimens and the time for the unsaturated polyester. figure (4) shows the relationship between the temperature of the wall surface (t1and t2) of the tested specimens and the time for the different fiber volume fraction (vf=3%and15%) for experimental work when the thermal flow in the parallel direction to the glass fibers. figure (5) shows the relationship between the temperature of wall surface (t1and t2) and time for the different fiber volume fraction (vf=3%, and15%) for experimental work when the thermal flow in the perpendicular direction to the direction of the glass fibers. the figures (4 and 5) indicated that the experimental temperatures (t2and t3) reach the equilibrium state ( t2=t3 ) at different time. the relationship between the theoretical thermal conductivity and the fiber volume fraction (vf) for parallel and perpendicular direction of glass fibers is presented in figure (6), it can be seen that the results of the parallel direction was higher than the results when the fiber arranged in the perpendicular direction to the heat flow. it can be seen that the difference between the parallel and the perpendicular direction increases with increasing the fiber volume fraction as shown in the table (2). also it was found that the maximum difference between the theoretical results of the parallel direction and the perpendicular direction was (42.6%) at the fiber volume fracture (vf=15%) and the minimum difference was 14.2% at fiber volume fracture (vf=3%). the experimental results indicated that the maximum percentage of improvement of the experimental thermal conductivity for parallel arrangement was96.9% at the vf=15%, and the maximum improvement for perpendicular was 13.77% at the vf=15% this difference is due to the arrangement and orientation of the glass fibers. figure (7) shows the relationship between the theoretical and experimental thermal conductivity with different values of volume fraction of glass fibers for parallel direction, while the relationship for perpendicular direction is illustrated in figure (8). the relationship between the theoretical and the experimental thermal conductivity with the different values of the fiber volume fraction (3% and 15% ) for parallel and perpendicular arrangement is illustrated in figure (9), while the same relationship different values of the fiber volume fraction (9% and 15% ) is illustrated in figure (10). figures (6, 7, 8, 9 and 10) indicated that the theoretical thermal conductivity is greater than the experimental conductivity. the difference between the theoretical and the experimental conductivity is due to the fact that the theoretical conductivity is real values and obtained from the equations while the experimental values depend on the properties of matrix material , fibers, the precision of instrument, reading, and environmental condition. from the experimental and the theoretical results found time (min.) w al l s u rf ac e t em p er a tu re ( c o ) 0 5 10 15 20 25 30 35 40 45 0 5 10 15 20 25 30 35 40 45 50 time(min) t h e t e m p e ra tu re o f w a ll s u rf a c e (c ) t1 t2 mohammed sellab hamza al-khwarizmi engineering journal, vol. 4, no. 3, pp 85-97 (2008) 90 that for the parallel direction the maximum difference of thermal conductivity between the theoretical and experimental values was (3.82%) at (vf = 15%) while the minimum value was (2.94 %) at (vf = 3 %). for the perpendicular direction it was found that the maximum difference of thermal conductivity between the theoretical value and experimental value was (2.56%) at (vf =15%) while the minimum value was (1.71%) at (vf =3 %). it is clear from the results of the this research that the thermal conductivity increases with increasing fiber volume fraction of the glass fibers but the percentage of increase for parallel direction is more than that for perpendicular direction for both theoretical and experimental work. all the results of the theoretical and experimental results prove that the parallel arrangement is the best for application and the improvement of the thermal conductivity depend on the properties of the matrix and the reinforcement material and the orientation of the fibers. 20 25 30 35 40 45 50 55 60 0 5 10 15 20 25 30 35 40 45 50 55 60 65 y y1 (a) (b) vf=15% (b) fig.4. relationship between the experimental e wall surface temperature (t1and t2) of the tested specimens and the time when the fiber arranged in the parallel direction at: a) volume fraction of fiber 3% b) volume fraction of fiber 15%. vf =3% time (min) w a ll s u r fa c e t e m p er a tu r e (c o ) t1 t2 parallel direction 20 25 30 35 40 45 50 55 60 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 y y1 w a ll s u r fa c e t e m p er a tu r e (c o ) t1 t2 parallel direction vf =15% time (min) mohammed sellab hamza al-khwarizmi engineering journal, vol. 4, no. 3, pp 85-97 (2008) 91 (a) vf=3% (a) (b) fig.5. relationship between the experimental wall surface temperature (t1and t2) of the tested specimens and the time when the fiber arranged in the perpendicular direction at: a) volume fraction of fiber 3%. b) volume fraction of fiber %15. fig.6. the relation between the theoretical thermal conductivity and the fiber volume fraction (vf) for parallel and perpendicular direction of manufactured specimens. 20 25 30 35 40 45 50 55 0 5 10 15 20 25 30 35 40 45 50 55 time (min.) t e m p e ra ti o n o f w a ll s u rf a c e ( c o ) t1 t2 (c o ) w a ll s u r fa c e t e m p er a tu r e (c o ) vf=3% 20 25 30 35 40 45 50 55 0 5 10 15 20 25 30 35 40 45 50 55 60 time(min.) t e m p e ra tu re o f w a ll s u rf a c e ( c o ) t1 t2(c o ) w a ll s u r fa c e t e m p er a tu r e (c o ) vf=15% 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 t h e r m a l c o n d u c ti v it y theoretical for parallel theoretical for perpendicular 0 3 6 9 2 15 fiber volume fraction ( % ) t h e r m a l c o n d u c ti v it y ( w /m .c o ) mohammed sellab hamza al-khwarizmi engineering journal, vol. 4, no. 3, pp 85-97 (2008) 92 fig.7. the relation between the theoretical and experimental thermal conductivity with the fiber volume fraction (vf) for parallel direction of manufactured specimens. fig.8. the relation between the theoretical and experimental thermal conductivity with the fiber volume fraction (vf) for perpendicular direction of manufactured specimens. 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 t h e rm a l c o n d u c ti v it y theoretical experimental 0 3 6 9 12 15 fiber volume fraction ( % ) t h e r m a l c o n d u c ti v it y ( w /m .c o ) 0.15 0.155 0.16 0.165 0.17 0.175 0.18 0.185 0.19 0.195 t h e rm a l c o n d u c ti ti v it y theoretical experimental 0 3 6 9 12 15 fiber volume fraction ( % ) t h e r m a l c o n d u c ti v it y ( w /m .c o ) mohammed sellab hamza al-khwarizmi engineering journal, vol. 4, no. 3, pp 85-97 (2008) 93 vf = 3% vf = 6% fig.9. the relation between the theoretical and experimental thermal conductivity with the different value of fiber volume fraction (vf = 3% and 6%) for parallel and perpendicular direction of manufactured specimens. 0.155 0.16 0.165 0.17 0.175 0.18 0.185 0.19 0.195 0.2 0.205 t h e rm a l c o n d u c ti v it y (w /m .c ) theoretical experimental parallel direction perpendicular direction t h e r m a l c o n d u c ti v it y ( w /m .c o ) 0 0.05 0.1 0.15 0.2 0.25 t h e rm a l c o n d u c ti v it y ( w / m .c o ) theoretical experimemtal parallel direction perpendicular direction t h e r m a l c o n d u c ti v it y ( w /m .c o ) mohammed sellab hamza al-khwarizmi engineering journal, vol. 4, no. 3, pp 85-97 (2008) 94 vf= 9 % vf= 15 % fig.10. the relation between the theoretical and experimental thermal conductivity with the different value of fiber volume fraction (vf = 9% and 15%) for parallel and perpendicular direction of manufactured specimens. conclusion the main conclusions of this research are: 1the thermal conductivity of composite materials is increasing with increasing of fiber volume fraction (vf), and for the parallel direction was higher than that for the perpendicular direction. 2the minimum value of experimental thermal conductivity for perpendicular arrangement was (0.172 w/m. c) at fiber volume fraction (3%) and the percentage of improvement and the increasing of the experimental thermal conductivity was 13.77% while the maximum value of experimental thermal conductivity for parallel arrangement was (0.237 w/m. c) 0 0.05 0.1 0.15 0.2 0.25 0.3 t h e rm a l c o n d u c ti v it y ( w /m .c ) theoretical experimental parallel direction perpendicular direction 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 t h e rm a l c o n d u c ti v it y ( w /m . c ) theoretical experimental parallel direction perpendicular direction mohammed sellab hamza al-khwarizmi engineering journal, vol. 4, no. 3, pp 85-97 (2008) 95 at fiber volume fraction (15%) and the percentage of improvement and the increasing of the experimental thermal conductivity was 96.9%. 3for parallel. arrangement, the maximum difference between the experimental and theoretical values of the thermal conductivity was (3.82%) at fiber volume fraction (15%) and the minimum difference was 2.94% at fiber volume fraction (3%). 4for perpendicular arrangement, the maximum difference between experimental and theoretical thermal conductivity was 2.56% at fiber volume fraction (15%) and the minimum difference was 1.71% at fiber volume fraction (3%). notation d1, d2 , d3 thickness of the brass disks (m) ds thickness of the composite specimen (m) e convection heat transfer coefficient (w/m 2 . c) k thermal conductivity (w/m. c) kc1 thermal conductivity of the composite specimen in the parallel direction of the fibers (w/m. c) kc2 thermal conductivity of the composite specimen in the perpendicular direction of the fibers (w/m. c). kf, km thermal conductivity of fibers and matrix (w/m. c). q heat flux. r radius of specimen (m). t1, t2,t3 temperature across the copper disks (1, 2, 3) (c). νc νm, νf volume of composite, matrix and reinforced material (m 3 ). vf,vm fiber volume fraction of matrix and fiber (%). dt/dx temperature gradient (%). p power pass though heating coil (watt) i electric current pass though heating coil(ampere) v voltage across the terminal of heating coil(volt) references [1] zhan – sheng guo, shanyi du and boming zhang, “temperature distribution of the thick thermoset composite”, journal of modeling and simulation in materials science and engineering, volume 12, issue 3, (china) may, (2004). [2] murthy, dr. a. rama krishna and b.v rama krishna,” thermal analysis of epoxy based fiber-reinforced”, ie(i) journal–mc, vol.84, april, (2004) [3] f. rondeaux, ph. bready and j.m. rey, “thermal conductivity measurements of epoxy systems at low temperature”, cryogenic engineering conference (cec), (usa), july (2001). [4] raimund rolfes,” 2d finite element formulation for 3d temperature analysis of numerical simulation of heat transfer”, journal of numerical simulation of heat transfer, germany, may, (2001). [5] lamees a. khalaf, "studying the mechanical and physical properties for unsaturated polyester reinforced by fiber glass and nylon fiber composites", m.sc. thesis, university of technology, materials engineering department (2006) baghdad iraq. [6] m.w. pilling, b. yates, m.a. black, “the thermal conductivity of carbon fiber – reinforced composites “, journal of materials science, vol.14, (1979). [7] saad m. elie, "studied the mechanical properties and thermal conductivity for polymer composite material reinforced by aluminum and aluminum oxide particles", m.sc. thesis, university of technology, materials engineering department (2007) baghdad iraq . [8] b.w. james and p. harrison,” analysis of the temperature distribution, heat flow and effective thermal conductivity of homogenous composite materials with anisotropic thermal conductivity”, journal of physics, vol.d, applied physics, issue 9, sept. (1992). [9] charles a sorrell, “advanced nanoporous composite materials for industrial heating applications”, applied sciences laboratory, inc., http://www.eere.energy.gov/industry/imf/pdfs /ibni.composite. pdf., (2002) [10] w. bolton,” engineering materials technology”, butterworth – heinemann, third edition, (1998) great britain. http://www.eere.energy.gov/industry/imf/pdfs/ibni.composite http://www.eere.energy.gov/industry/imf/pdfs/ibni.composite mohammed sellab hamza al-khwarizmi engineering journal, vol. 4, no. 3, pp 85-97 (2008) 96 [11] oronzio manca, biagio morrone, giuseppe romano, “analysis of thermal response of composite materials “, dipartimento ingegneria aerospaziale meccanica, ttp://event.ua.pt/ds2005/manca3.pdf., italy, (2005). [12] william d. callister,” materials science and engineering an introduction”, sixth edition, john wiley and sons, inc., (2003).u.s.a .new york. [13] munshid h. muhammad, study of mechanical and thermal behaviour of hybrid composite from carbon and kevlar fibers m.sc. thesis, university of technology, al-rasheed college for engineering and sciences applied science department (1989)baghdad iraq . [14] salwin b. abid al-wihid, study of mechanical properties of hybrid composite from carbon and kevlar fibers m.sc. thesis, university of technology, alrasheed college for engineering and sciences applied science department (1989) baghdad iraq. mohammed sellab hamza al-khwarizmi engineering journal, vol. 4, no. 3, pp 85-97 (2008) 97 الموصليت الحراريت دراست تأثير الكسرالحجمي أللياف الزجاج على للمواد المتراكبت البوليمريت محمذ صالب حمزة الدامعح الركىىلىخٍح / قسم هىذسح المىاد الخالصت على الرىطٍلح الحزارٌح (% 3 %,6 %,9 %,12 %,15) ذم فً هذا الثحث دراسح ذأثٍز الكسز الحدمً اللٍاف الشخاج وتىسة مخرلفح العٍىاخ طىعد فً مدمىعرٍه المدمىعح . حٍث طىعد العٍىاخ مه مادج الثىلً أسرز غٍز المشثع المقىاج تالٍاف الشخاج. للمادج المرزاكثح االولى كاود فٍها الٍاف الشخاج مزذثح تشكل مىاسي لالوسٍاب الحزاري, اما المدمىعح الثاوٍح وضمد ترزذٍة االلٍاف تشكل عمىدي على . االوسٍاب الحزاري اثثرد الىرائح العملٍح ان الرزذٍة المىاسي لاللٍاف ٌعطً مىطلٍح حزارٌح . فً فحض العٍىاخ ( leeś disk) اسرخذمد طزٌقح قزص لً حٍث كان مقذار الشٌادجفً . اعلى مه الرزذٍة العمىدي وان المىطلٍح الحزارٌح للمادج المرزاكثح ذشداد مع سٌادج الكسز الحدمً لاللٍاف للرزذٍة العمىدي كذلك اثثد الىرائح العملٍح ان اقل % 13.33للرزذٍة المىاسي و % 96.91المىطلٍح الحزارٌح تسثة الرقىٌح تااللٍاف هى اما اعلى قٍمح كاود (vf=3%)للرزذٍة العمىدي عىذ الكسز الحدمً (0.172w/m.c)قٍمح للمىطلٍح الحزارٌح كاود (0.327w/m.c) ًللرزذٍة المىاسي عىذ كسز حدم(vf = 15%.) this is an open access article under the cc by license: comparative transfer learning models for end-to-end self-driving car yahya ghufran khidhir* ameer hussein morad** *department of mechatronics engineering/ al-khwarizmi college of engineering/ university of baghdad ** department of information and communication engineering / al-khwarizmi college of engineering/ university of baghdad *email: yahia.ghofran1202a@kecbu.uobaghdad.edu.iq **email: ameer@kecbu.uobaghdad.edu.iq (september 2022 19 2022; accepted august 1received ) https://doi.org/10.22153/kej.2022.09.003 abstract self-driving automobiles are prominent in science and technology, which affect social and economic development. deep learning (dl) is the most common area of study in artificial intelligence (ai). in recent years, deep learning-based solutions have been presented in the field of self-driving cars and have achieved outstanding results. different studies investigated a variety of significant technologies for autonomous vehicles, including car navigation systems, path planning, environmental perception, as well as car control. end-to-end learning control directly converts sensory data into control commands in autonomous driving. this research aims to identify the most accurate pre-trained deep neural network (dnn) for predicting the steering angle of a self-driving vehicle that is suitable to be applied to embedded automotive technologies with limited performance. three well-known pre-trained models were compared in this study: alexnet, resnet18, and densenet121. transfer learning was utilized by modifying the final layer of pre-trained models in order to predict the steering angle of the vehicle. experiments were conducted on the dataset collected from two different tracks. according to the study's findings, resnet18 and densenet121 have the lowest error percentage for steering angle values. furthermore, the performance of the modified models was evaluated on predetermined tracks. resnet18 outperformed densenet121 in terms of accuracy, with less deviation from the center of the track, while densenet121 demonstrated greater adaptability across multiple tracks, resulting in better performance consistency. keywords: autonomous driving, deep learning, end-to-end learning, self-driving car, embedded system. 1. introduction self-driving cars have emerged as one of the most actively contested and researched topics in recent years. despite their association with the automotive industry, these systems belong to the field of robotics as part of the third robotic revolution. [1]. from a philosophical and scientific standpoint, there are various predictions regarding how selfdriving automobiles will impact our lives. automobiles play an important part in modern civilization, which is defined by a high level of mobility. it is estimated that approximately one billion automobiles are on the roads worldwide. autonomous driving, or intelligent driver assistance, is expected to result in a 90% reduction in road accidents; a 60% reduction in carbon dioxide emissions (due to smart trajectory planning); and savings of more than 1 billion hours every day for commuters around the world [2][3]. autonomous vehicles will not only improve the al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 18, no. 4, december, (2022) p. p. 4559 mailto:yahia.ghofran1202a@kecbu.uobaghdad.edu.iq mailto:ameer@kecbu.uobaghdad.edu.iq https://doi.org/10.22153/kej.2022.09.003 yahya ghufran khidhir al-khwarizmi engineering journal, vol. 18, no. 4, p.p. 4559 (2022) 46 mobility of those who are elderly or disabled; but will also reduce transportation energy consumption by up to 90%. [4]. self-driving cars are autonomous decisionmaking systems that analyze streams of observations obtained from multiple onboard sources, such as cameras, radio detection and ranging sensors, light detection and ranging sensors, ultrasonic sensors, global positioning system units, and/or inertial sensors, in which there is no human driver [5]. the camera is the most essential component of a vehicle's suite of sensors. the vast amount of data collected by a vehicle's cameras necessitates significant processing power in order to extract useful information. the only method for extracting information from incoming images is computer vision. sequential pipelines (perception-planningaction) or end-to-end learning are used to make driving decisions. pipelines that follow the classic approach, in which first objects are recognized in the input image, then a path is planned, and lastly, the computed control values are performed. in contrast, the end-to-end method employs a unique theory to steer a vehicle, figure 1. this strategy focuses on developing an ai model that mimics human driving. a human driver constantly makes steering predictions based on an immediate analysis of observed visuals. [6]. fig. 1. deep learning-based self-driving car. end-to-end learning control, as defined in the implementation of autonomous driving, where an image provided by a front-facing camera is fed into a neural network that then generates the car's control signals such as steering angle, throttle, and braking [5]. the primary advantage of this technique is that it learns the entire function automatically, from raw pixels to steering angles, without the need for any human intervention in the form of feature design and selection, geometry, camera calibration, or manual adjustment of parameter values. to be more specific, the goal of end-to-end learning is to diminish or eliminate the need for human expertise in terms of feature extraction and to solve issues using just data [7]. in this paper, three well-known dl models have been modified to perform the task of end-to-end driving autonomously. the main objective of this study is to analyze and evaluate the modified models and determine the best predictive model among them for steering angle control using a dataset collected from two different tracks. in addition, the study decides which model is most suitable to be applied to low-performing hardware with high qualitative results. the dl models have been selected according to their widespread use. results from the offered end-to-end learning network may find practical usage in applications like warehousing and delivery vehicle robot cars. it is important for practical industrial applications to be able to deploy well-known dnn solutions, such as those offered in this study, on integrated vehicle applications that have low-power technologies at low costs and compact sizes. the relevant work will be presented in the next section. section iii describes the research method. section iv: experiments and results. the last portion contains the conclusion. 2. related work this section summarizes some of the related works proposed to perform the task of autonomous end-to-end driving. end-to-end learning models that are trained on sensor inputs and supervised by humans are one of the most promising approaches to achieving fully autonomous performance. a limited number of published works have used dnns as part of a complete model to command a real-world autonomous system. researchers in the field of autonomous vehicles rely heavily on artificial datasets to evaluate the efficacy of dl. in the paper [8], the authors describe a convolutional neural network (cnn) that can solve the problem of autonomous lateral control. the input image size to the network is (70x160x3). a proper steering angle was generated using cnn, enabling the automobile to complete laps. on simulated unknown tracks, cnn's steering control was tested. unfamiliar single-lane routes were successfully navigated 89.02 % of the time. however, the training dataset was small and did not cover a wide range of scenarios. yahya ghufran khidhir al-khwarizmi engineering journal, vol. 18, no. 4, p.p. 4559 (2022) 47 in [9], the researchers designed dl models for the input image size of (70x160x3) in order to carry out longitudinal and lateral vehicle control. predictions of both speed and steering angle were made by developing two separate models. max-pooling was employed in each convolution in dnn. the dualaction model completed all loops of the simulation track without leaving the designated lanes, demonstrating full autonomy. however, there was insufficient memory for training due to the excessive use of threads. in addition, another group of researchers [10] developed a lightweight dnn model (j-net) for car steering angle control and compared this model to two other models, alexnet and nvidia's model. input images to the first convolutional layer of the proposed models have a size of (65x320x3). successful autonomous driving was measured, inferred, and analyzed using a simulator environment. in comparison to the other two approaches, j-net had the best latency and frame rate. the j-net lite model, however, has not been implemented on an embedded platform with a limited number of processing cores. applying dl techniques including transfer learning, [11] study compared two different models for accurate steering angle prediction. the models were a 3d convolutional model with long short-term memory layers and residual neural network (resnet50) with the input image sizes (120x320x3) and (224x224x3), respectively. the models were trained using the udacity self-driving car dataset. the (resnet50) model outperformed the other model with an rmse of 0.0709. nonetheless, the paper's models benefit from limited data augmentation, which is a significant limitation. the topic of steering angle regression is framed as a classification challenge with an imposed spatial connection between neurons in the output layer. another study [12] presented a comparison between the three transfer learning models: visual geometry group (vgg16), resnet-152, densely connected convolutional networks (densenet201, and nvidia’s model for steering angle control. the input image size for all models was (66x200x3). the models were trained with 25 minutes of driving time at 30 frames per second using a raspberry pi camera. nvidia’s model outperformed the other models with a mean square error (mse) of 0.3521. the authors used random videos from youtube to visualize the performance of nvidia’s model. using a monocular self-driving car prototype, the authors of [13] proposed a dnn applied to a raspberry pi with an input image size of (120x160x3) for steering angle prediction. as a vehicle platform, a 1/10 scale rc car was employed. data was acquired from an oval and an 8-shaped track equipped with traffic signs. experiments demonstrate that the autopilot product is capable of maintaining a lane with a crossentropy cost function accuracy of 89.04%. regardless of lane markers, the vehicle's top speed is 5–6 km/h at 10 frames per second. nevertheless, the camera used in their car prototype lagged by 300-350 milliseconds. multichannel convolutional neural networks (m-cnns) were utilized for vehicle speed and steering angle calculations in [14]. the model uses (227x227x3) image size from front-view camera recordings and feedback speed sequences as its input. the public udacity dataset and the gathered saic dataset are used to evaluate the suggested technique. the proposed concept was contrasted with the updated versions of the cg network and pilotnet from nvidia. with an mae of 1.26 degrees for steering angle and 0.19 meters per second for speed values, the m-cnns were better than the implemented nvidia pilotnet and the cg network. numerous studies have focused on constructing dnns from low-resolution images for deployment throughout low-performance embedded systems. this research aims to develop an end-to-end method for forecasting the steering angle using well-known dnns that can be implemented on low-performance embedded systems. in addition, provide an overview of well-known dl models, such as alexnet, resnet18, and densenet-121, that accurately predict autonomous driving commands but have not previously been studied. to train the selected models, data were collected from two distinct tracks with image sizes of (224x224x3), which is the most frequent resolution. furthermore, the presented work's accuracy and consistency were examined and compared. the following are the paper's main contributions: 1. image classification convolutional neural networks alexnet, resnet18, and densenet121 were modified and deployed for end-to-end autonomous driving. 2. the jetson nano 2gb, a low-performance embedded system, was applied to evaluate the modified models. consequently, it proved that resnet18 and densenet121 are well-suited to be employed in low-performance embedded devices. 3. the majority of data was collected from the first track, while some information was obtained yahya ghufran khidhir al-khwarizmi engineering journal, vol. 18, no. 4, p.p. 4559 (2022) 48 from the second. the results demonstrate that the robot can drive 89% of the time on an untrained track. 4. the performance of resnet18 and densenet121 was evaluated on two different tracks to demonstrate their suitability for autonomous driving. resnet18 outperformed densenet121 in terms of precision, with less deviation from the center of the track. densenet121 was more adaptable across tracks, resulting in better consistency. 3. method this section explains the algorithms used in this work in considerable detail followed by the robot system architecture. 3.1. convolutional neural networks (cnn) cnn is utilized to classify the labels using a supervised learning technique [15]. the first phase in the cnn architecture is the convolution layer, where a 2d convolution operation is applied to the image. in convolution, the three-channel rgb with a 2d size image is convolved with kernels. the output of convolution known as feature map focuses on particular features in the input image regardless of their location in the image. the convolutions with kernels are used to extract lowlevel particular features (like edges and corners of the road) from the previous layers and combine them with higher-level extracted features (full objects of the road) in the next hidden layers. which reduce the size of the image and increase the number of parameters (weights and biases) [16]. as the number of parameters increases, more training time is required. the activation function is applied after the convolution. the activation function is responsible for determining whether or not a neuron is fired. in other words, it will use simpler mathematical operations to decide whether or not the neuron's input is essential to the network. calculating a weighted sum and then adding bias to it is how the activation function determines whether or not a neuron should be activated or not[17]. the activation function adds nonlinearity to a neuron's output [18]. it transforms the input, allowing it to learn and execute highly complicated tasks. in this work, the (rectified linear unit) [19] activation function is applied to the hidden layers because it requires fewer mathematical operations and thus is faster to compute compared to tanh and sigmoid and neglects the effect of gradient vanishing. if x is positive, it returns x and 0 if x is negative or equal to zero. the operation called pooling was next performed, which decreases the feature maps' dimensionality (resolution) and hence their output (the output of the convolutional layer) resolution [20][21]. this method helps to reduce spatial variance by removing unnecessary information from the neuron's receptive field by taking the maximum (max pooling) or average (average pooling) value of the neuron (filter window). pooling not only helps in object recognition in images independent of their position but also reduces the number of parameters to train by reducing the number of pixels, thereby contributing to the prevention of overfitting. the two-dimensional feature vector of the final convolution layer is flattened into a long onedimensional array, which is known as a fully connected layer fc, or dense layer. a subset of fc layers maps the spatial features of convolution layers and pooling layers to the final outputs of the network, which directly predicts the steering angle value. the steering angle of each image is represented by a single point on the image. in this study, the dataset consisting of road images and steering angle labels is used for training purposes. the trained model predicts the steering angle in realtime while detecting unlabeled images, as regression is the process of forecasting a value based on previous data. adam is the optimizer implemented by cnns in the current study. optimizers modify neural network parameters including weights and learning rates. the accuracy of the model is computed employing loss function. as described in section 2.5, this study suggests utilizing mse loss function to train a regression network for the task of predicting continuous steering angles from models. the (mse) illustrates how far away from reality predictions were. 3.2. cnn models the three cnn architectures used in this work are resnet18, densnet121, and alexnet. all three models take a 224* 224 image size as input. residual learning was used in resnet18 to overcome the loss of precision with increasing network depth. it has 18 layers, including 17 convolutional layers and one fc layer with 3x3 filters. this network also has approximately 11 million parameters. down sampling is performed yahya ghufran khidhir al-khwarizmi engineering journal, vol. 18, no. 4, p.p. 4559 (2022) 49 by convolutional layers with a stride of two, as shown in figure 2[22]. the final fc layer and softmax were removed from the original network, and an additional fc layer was added to convert 512 features to one output feature (steering angle). densenet was developed to address the problem of vanishing gradients in high-level neural networks [23], which causes accuracy to decrease. the network has 121 layers, which are divided into four dense blocks made up of convolutional layers and transition layers in between to facilitate information flow between layers, as shown in figure 3. densnet121 is made up of 7.2 million parameters. the original network's final fc layer and softmax were removed, and an additional fc layer was created to convert 1024 features to one output feature (steering angle). fig. 2. resnet18 architecture. fig. 3. densenet121 architecture. yahya ghufran khidhir al-khwarizmi engineering journal, vol. 18, no. 4, p.p. 4559 (2022) 50 3.3. robotic system architecture the block diagram of training dnn is shown in figure 4. firstly, the required data was collected manually by driving the car. secondly, data preprocessing and data augmentation were applied before feeding the images to the cnn models for training. finally, the trained model was used in the inference track for the test. the successful model was one that drove independently on both tracks while avoiding the orange bolder lines and staying on the centreline. fig. 4. block diagram of the training dnn. 3.4. database acquisition collecting, inferring, and evaluating data for autonomous driving was done on two tracks. data were collected along the first, 3x2 meter path, while tests and evaluations were conducted along the second, 4x2 meter path with curves in the middle, figure 5(b). the inference track was brighter than the collection track. the dataset's features are represented by images, with the corresponding steering angles serving as labels. the jetracer robot was placed on the representative track to collect data for the training process. continuous orange lines on the borders and dashed white lines in the center define the track. a single camera was installed instead of three cameras to capture frames in three different positions (center, left, and right). the objective was to keep the car in the center of the road. as a result, the images from the camera at the same level in the middle, left, and right were taken with the same steering measurement value. the measurements are manually entered from a remote pc while the images are being captured by clicking the desired xy coordinates on each frame as shown in figure 6. the x-axis latitude represents the amount of angle from left to right and is controlled by the servo motor with a range of -1.0 to 1.0. as a result, a unique dataset is created for the training process. to obtain high-quality results, the images and measurements should be collected manually while driving in the manner we expect during testing. data augmentation has been used to improve training results as well as drive the robot clockwise and counterclockwise[24][25]. the term "augmentation" refers to the technique of improving the training data without affecting the dataset's essential characteristics. the amount of data in the training directory is increased by adding slightly modified copies of pre-existing data. the augmentation procedure in our work involves only flipping the images around vertical access. the steering angle should be inverted while flipping each frame. therefore, the new steering angle equals: 𝑆𝑡𝑒𝑒𝑟𝑖𝑛𝑔 𝑎𝑛𝑔𝑙𝑒 𝑎𝑓𝑡𝑒𝑟 𝑓𝑙𝑖𝑝𝑝𝑖𝑛𝑔 = (−1) ∗ 𝑜𝑟𝑖𝑔𝑖𝑛𝑎𝑙 𝑠𝑡𝑒𝑒𝑟𝑖𝑛𝑔 𝑎𝑛𝑔𝑙𝑒 … (1) yahya ghufran khidhir al-khwarizmi engineering journal, vol. 18, no. 4, p.p. 4559 (2022) 51 so as to adapt the robot’s throttle to its high speed in a straightforward path and slower speed in turns, the throttle is equal to: 𝑌 = 1 – 𝑎𝑏𝑠 (𝑋) … (2) as a result, when the car is driving in the center of the path, x = 0, the throttle is at its maximum value, and in sharp turns, the throttle is at its minimum value. (a) (b) fig. 5. database acquisition tracks (a) data collection track (b). inference track fig. 6. database acquisition. the number of images collected from the first track in figure 5(a) was 681 in total. 83 samples from track b's inside turns were added to the dataset to enable the robot to drive on both tracks, figure 5(b). the images' resolution was (224x224x3). (224 pixels width, 224 pixels height, and 3 channels of rgb colors). the number of images increased to 1528 samples after data augmentation. the dataset was divided into two portions: 80% for training and 20% for validation. figure 7 depicts the normalized steering angles associated with each frame. yahya ghufran khidhir al-khwarizmi engineering journal, vol. 18, no. 4, p.p. 4559 (2022) 52 fig. 7. dataset of normalized steering angles. 3.5. training and hyper-parameter on the google colab platform, the three models were trained in the python programming language. color jitter data pre-processing was used in addition to data normalization because of the difference in color brightness between data collection and inference tracks. each model was trained separately with the same hyperparameters. the adam [26] optimizer utilized with an initial learning rate of (0.0005). to avoid missing local optima, it's recommended to keep the learning rate low because it's more stable. in spite of the above fact, it is possible that a minimal learning rate could lead to overfitting. the number of epochs was 70, with early stopping patience of 10 epochs. the batch size was set to 8. as the batch size is reduced, the end losses are reduced too. as a suitable loss function for regression networks, (mse) [27] was selected to minimize the error between the steering forecast and the steering measurements. mse is calculated by taking the average of the squared difference between the expected value and the actual value. 𝑀𝑒𝑎𝑛𝑆𝑞𝑢𝑎𝑟𝑒𝑑𝐸𝑟𝑟𝑜𝑟 = 1 𝑁 ∑(𝑦𝑗 − �̂�𝑗) 2 … (3) 𝑁 𝑗=1 the vector �̂�𝑗 represents the values of n forecasts and 𝑦𝑗 is a vector that contains n true values. in order to get fast inference performance with a simple workflow, the models were converted and optimized using the pytorch to tensorrt converter (torch2trt) to be applied to the jetson nano embedded system. all three models were trained with the same hyper-parameters and datasets, differing only in the number of epochs. these differences arose from early stopping to reduce the overfitting. the model was saved automatically if there was no progress in validation loss for 10 epochs. the performance of the models was evaluated by their ability to navigate a robot through predetermined tracks. the models were determined to be successful based on their ability to drive autonomously on both predetermined tracks. as such, the model was determined to be a failure if the car deviated from the path of the predetermined tracks. the robots were driven through each track three times. their paths were recorded by different colored markers that were affixed to the back of the robot. images were captured from the paths and the trajectories were converted into xy coordinates in pixels. the frechet distance theorem was used to measure how different the drawn paths were from each other in relation to the centre of the track.[28][29] the frechet distance between two curves can be defined mathematically as: 𝛿𝐹(𝑃, 𝑄) = min {max 𝑑 (𝑃(𝛼(𝑡)), 𝑄(𝛽(𝑡)))} 𝛼[0,1] → [0, n] 𝑡 ∈ [0,1] 𝛽[0,1] → [0, m] …(4) yahya ghufran khidhir al-khwarizmi engineering journal, vol. 18, no. 4, p.p. 4559 (2022) 53 where 𝑃 and 𝑄 are polygonal curves of length n and m, 𝛼(𝑡) and 𝛽(𝑡) are two continuous and increasing functions, and 𝑑 (𝑃(𝛼(𝑡)), 𝑄(𝛽(𝑡))) is the euclidian distance between 𝑃(𝛼(𝑡)) and 𝑄(𝛽(𝑡)). according to equation (4), the frechet distance algorithm first determines the maximum distance that can exist between curves 𝑃 and 𝑄 as they progress along their respective paths for each value of the functions 𝛼(𝑡) and 𝛽(𝑡), then maintains the minimum distance that can exist between them. 4. experiments and results when the findings of this research were compared to those of similar studies, it was revealed that the metrics and datasets utilized were not standardized, and there was a lack of transparency in the presentation of the results. for instance, the percentage of switching lanes over time on multi-line tracks is quantified as a "degree of autonomy" in [8], [9]. the sample sizes in the training, validation, and testing sets in the simulated data presented in [8], [9], and [10] are significantly different. in studies, the following metrics were employed: [10], [12] mse, [13] cross-entropy, [14] mae, and [11] rmse. mse was implemented to evaluate the performance of the proposed architectures on the validation dataset in this study. as shown in table 1, desnenet121 has the best overall performance, with a score of 0.0057. however, resnet18's value of 0.0058 is quite close to densenet121's value. among the two remaining models, resnet18 and densenet121, resnet18 had the larger file size. the size of the model indicates the complexity of the model. after training three cnn architectures on google colab, testing for the alexnet model was suspended since its 217 mb size exceeded the storage capacity of the jetson nano 2g. as a result, this model was not considered for further examination. only resnet18 and densenet121 were tested on the aforementioned tracks using the jetson nano 2g. table 1, mse and model size network mse model size resnet18 0.0058 42.7 mb densenet121 0.0057 27.1 mb alexnet 0.1333 217 mb in order to compare the models' accuracy and repeatability. due to the simplicity, three full laps of driving were recorded at a constant speed. figure 8 shows the drawn paths of the robot as it navigates each predetermined path, whether using the resnet18 model or the densenet121. recorded trajectories suggest that both resnet18 and densenet121 guided the robot through both of the predetermined paths. however, there were some differences between the two models. the frechet distance was applied to show how both models' curves deviated from the centerline. in the initial step of the frechet distance algorithm, it calculates the maximum distance between two pairing points of each model's drawn path and the centerline path. in addition to this, it selects the smallest distance from all maximum pairwise distances to demonstrate the dissimilarity between the two paths. figures 8 (a) and (b) show the paths drawn by the resnet18 model for three full laps on both trajectories. figures 8 (c) and (d) show the paths drawn by densenet121 for three full laps on both tracks. table 2 shows the calculated dissimilarity distances between each curve and the centerline for three turns. table 2 shows that when comparing resnet18 and densenet121, the former has relatively small dissimilarity distances. resnet18 demonstrated an average distance of 3.26 cm from the track's centerline on the first track. on the same track, densenet121 achieved an average distance of 4.39 cm. resnet18 achieved an average distance of 4.12 cm on the second track. densenet121 achieved an average distance of 4.38 cm on the same track. resnet18 appeared to be less accurate on the second track when compared to the first. densenet121, on the other hand, produced comparable results on both tracks. this means that resnet18 is more accurate than densenet121, but densenet121 can adapt to different tracks and perform more consistently. yahya ghufran khidhir al-khwarizmi engineering journal, vol. 18, no. 4, p.p. 4559 (2022) 54 yahya ghufran khidhir al-khwarizmi engineering journal, vol. 18, no. 4, p.p. 4559 (2022) 55 fig. 8. the drawn paths for three full laps on both tracks using resnet18 and densenet121. (a) the drawn paths of resnet18 on the first track. (b) the drawn paths resnet18 model on the second track. (c) the drawn paths of the densenet121 model on the first track. (d) the drawn paths densenet121 model on the second track. table 2, the dissimilarity between curves and centerline using discrete frechet distance. first track second track num of turns resnet18 densenet121 resnet18 densenet121 first turn 1.81 cm 2.69 cm 3.57 cm 3.12 cm second turn 3.21 cm 4.76 cm 4.39 cm 4.89 cm third turn 4.77 cm 5.731 cm 4.41 cm 5.13 cm figure 9 shows the predicted steering with frames for each model as a performance measure. figure 9 also depicts three types of driving paths: (a) internal turns, (b) straightforward paths, and (c) long-end turns. the two large oscillations depict the long end turns with high deviation from the track center as the car drives counterclockwise. with less oscillation, the straightforward path is depicted. the small upside-down oscillations represent short internal turns in the middle of the path. furthermore, as shown in figure 9, both densenet121 and resnet18 have higher steering angle deviation compared to the collected dataset in figure 7. based on the trained dataset, resent18 outperforms than densenet121, as evidenced by its higher steering angle of 0.8 (i.e., closer to the center of the track). the steering angle of densenet121 was approximately 0.98, indicating that it was quite distant from the track's center. yahya ghufran khidhir al-khwarizmi engineering journal, vol. 18, no. 4, p.p. 4559 (2022) 56 fig. 9. relative deviation from the center of the trajectory per one full lap of autonomous driving using resnet18 and densenet121. (a) internal turns (b) straightforward path (c) long-end turns. 5. conclusion in this study, a comparison of three transfer learning models (alexnet, resnet18, and densenet121), which are capable of handling the task of autonomous driving, was conducted. in addition, the modifications of the pertained models' designs and the system architecture for the prediction of steering angle have been described. three architectures were applied and evaluated on two featured paths. through a comparative analysis of three well-known dl models. the main goal of this study is to determine the best dl model for predicting steering angle. the numerical results based on the loss function (mse) and the frechet distance were discussed. the main idea of this research is to determine whether the better result for the steering angle prediction problem can be obtained by employing less sophisticated algorithms that can be implemented on lowperformance hardware. the results show that both resnet18 and densenet121 are compatible with the jeston nano 2g embedded system. the results demonstrate that the resnet18 is more accuracy than densenet121, whilst densenet121 are able to adapt new tracks and keep the performance stable over time. on the other hand, resent18's is achieved a good fitted line with the trained dataset, as indicated by its higher steering angle of 0.8 (i.e., closer to the center of the track). densenet121's steering angle was about 0.98, which is an extremely wide divergence from the track's center. in addition, different experiments were carried out in order to investigate how the training dataset affected driving performance. the results demonstrate that the best driving performance was obtained when the validation loss was less than 1% and the vehicle was capable of handling abrupt curves while remaining on the centerline. the biggest obstacle in the end-to-end dl technique is its reliance on clean and extensive training data. yahya ghufran khidhir al-khwarizmi engineering journal, vol. 18, no. 4, p.p. 4559 (2022) 57 the future idea is to add an imu sensor to measure the robot's actual orientations along the path in order to use them to find the difference between the neural network's expected steering angle and the imu sensor's output. 6. references [1] d. b. o. boesl and b. liepert, “4 robotic revolutions proposing a holistic phase model describing future disruptions in the evolution of robotics and automation and the rise of a new generation ‘r’ of robotic natives,” ieee int. conf. intell. robot. syst., vol. 2016-novem, pp. 1262–1267, 2016. 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(2022) 45-59، صفحة 4العدد، 18مجلة الخوارزمي الهندسية المجلد هديل فاروق حميد 59 من النهاية الى النهاية لسيارات الذاتية القيادة مقارنة نماذج التعلم النقل مير مراد حسين**أيحيى غفران خضر* * قسم هندسة الميكاترونكس/كلية الهندسة الخوارزمي/ جامعة بغداد جامعة بغداد ** قسم هندسة المعلومات واالتصاالت/كلية الهندسة الخوارزمي/ yahia.ghofran1202a@kecbu.uobaghdad.edu.iq*البريد االلكتروني: ameer@kecbu.uobaghdad.edu.iq*البريد االلكتروني: * الخالصة ( حاليًا أحد أهم مجاالت dlوتؤثر على التنمية االجتماعية واالقتصادية. يعد التعلم العميق ) والتكنولوجيا،السيارات ذاتية القيادة لها مكانة بارزة في العلوم ات ذاتية القيادة وحققت نتائج باهرة. تدرس تم تقديم حلول قائمة على التعلم العميق في مجال السيار األخيرة،(. في السنوات aiالدراسة في الذكاء االصطناعي ) والتحكم البيئي،واإلدراك المسار،وتخطيط السيارات،بما في ذلك أنظمة المالحة في القيادة،هذه الدراسات مجموعة متنوعة من التقنيات المهمة للمركبات ذاتية سية إلى أوامر تحكم في القيادة الذاتية. تهدف هذه الدراسة إلى تحديد الشبكة العصبية في السيارة. التحكم في التعلم الشامل هو التحويل المباشر للبيانات الح امل يمكن ( األكثر دقة التي تم تدريبها مسبقًا للتنبؤ بزاوية التوجيه لمركبة مستقلة. الهدف من هذا المشروع هو إنشاء قدرات قيادة ذاتية بالكdnnالعميقة ) resnet18و alexnetقمنا بمقارنة ثالثة نماذج معروفة جيدًا: اقتراحنا،المدمجة ذات األداء المحدود. في استخدامها مع تقنيات السيارات جارب على . تم استخدام تعلم النقل من خالل تعديل الطبقة النهائية من النماذج المدربة مسبقًا من أجل التنبؤ بزاوية توجيه السيارة. أجريت التdensenet121و لديهما أقل نسبة خطأ لقيمة زاوية التوجيه. densenet121و resnet18فإن الدراسة،نات التي تم جمعها من مسارين مختلفين. وفقًا لنتائج مجموعة البيا مع انحراف الدقة،من حيث densenet121أفضل من resnet18تم فحص أداء النماذج المعدلة على مسارات محددة مسبقًا. كان أداء ذلك،عالوة على .مما أدى إلى أداء أكثر اتساقًا المختلفة،أكثر مرونة عبر المسارات densenet121أقل عن مركز المسار، بينما كان mailto:yahia.ghofran1202a@kecbu.uobaghdad.edu.iq mailto:ameer@kecbu.uobaghdad.edu.iq <4d6963726f736f667420576f7264202d20e3cde3cf20e6cec7e1cf20dacce3ed20e6c7cde3cf20d3e1e6e337302d203833> al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 15, no. 3, sptember, (2019) p.p. 7083 electrodepositing of multi-layer ni-ag coated by copper nanoparticles for solar absorber mohammed j. kadhim* khalid a. sukkar** ahmed s. abbas*** *,***department of production and metallurgy engineering/ university of technology/ baghdad/ iraq **department of chemical engineering / university of technology/ baghdad/iraq *email: alimohammed1957@yahoo.com **email: 150001@uotechnology.edu.iq ***email: ahmedsaoom@yahoo.com (received 25 november 2018; accepted 2 june 2019) https://doi.org/10.22153/kej.2019.06.009 abstract in this work, the effect of the addition of bright nickel plating and silver carried out by the electroplating method has been studied, on the coating of copper nanoparticles on the copper base metal via the process of thermal evaporation. the improvement of the solar absorber using cunp in combination with the bright nickel and silver was obtained to be better than copper nanoparticles individually. a bright nickel enhanced the absorbed thermal stability. also, other optical properties, absorptions, and emissivity slightly decreased from (93% to 87%), while the existence of silver had a slight impact on absorption of about (86.50%). on the other hand, thermal conductivity was evaluated using hot disk analyzer. the results showed a good improvement obtained by copper nanoparticles of about (89%) deposited on the copper substrate, while it decreased with 18.8% in the presence of bright nickel combined with copper nanoparticles. the other characteristics, like structure and phases of coating layers, were achieved using x-ray diffraction. topographic maps were obtained using an atomic force microscope and scanning electron microscope. keywords: bright nickel, copper nanoparticles cunp, pvd, silver, solar absorber. 1. introduction due to the increasing demand for energy, the need for alternative clean energy sources with the least emission of dioxide has increase; sun is one of the most important sources of energy at all, in order to convert this thermal energy into useful energy, selective coatings are emerging as an important industrial application [1, 2]. the proper coating of the selective solar absorber must possess two criteria; a high absorption across the wavelength of the solar spectrum in the ultraviolet area visible (uv-vis), and a low thermal emissivity close to the infrared (nir). in general, the optical properties are obtained by reflectance spectrophotometry, and the reflectance must be less than (10%) in the (uv-visible) range and more than (90%) in the (nir) [3]. because metals possess almost low thermal emissivity, coatings of the selective solar absorber are, in general, produced on the metallic substrates with high thermal conductivity and a good corrosion mohammed j. kadhim al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 7083 (2019) 71 resistance [4, 5]. there exist several processes and methods to produce the selective coatings, including paint, chemical vapor deposition (cvd), sol-gel, spray coating, and physical vapor deposition (pvd), electroplating is simple and an allured choice owing to its reproducibility, adequate governing over the thickness and morphology of the coating, short deposition times and less cost [3,4,6]. bright nickel is an allured, less-cost solar absorber metal, the coatings produced with the electrolyte and same formulations for the chemical converting baths exhibited good optical characteristics [7-9]. nickel is usually used as an intermediate layer to protect the thin film and prevent the diffusional problem of the nanoparticle to the material substrate also giving thermal stability [10, 11]. silver electroplating was used due to a good appearance, the highest electrical and thermal conductivity was the main remarkable as well as the possibility of depositing over the hollow, and table parts, in addition to corrosion resistance. industrial and engineering use of silver plating due to high thermal and optical properties resulting that popped up. it used, also in the mirrors, electronic and printed circuits [12, 13]. the field of solar selective coating attracted many researcher's interests. copper is an allured substrate metal for the selective coatings due to its more reflectance (less emissivity) close to nir, stability and good thermal conductivity. furthermore, copper is too convenient as a substrate for the electrodeposition. from the other side, copper nanoparticles are completely different from the bulk, where they characterized by their unique and distinctive properties in the field of thermal and electrical conductivity as well as their use in selective coating [14]. recently, researches have focused on using nanotechnology in the field of solar energy coatings in order to improve the efficiency of the absorber surface, j. el nady et al. (2016) [15], increased the efficiency of the solar absorber using black paint coated on copper once and comparing that with using black paint combined with bright nickel once again. nanoparticles layer consist of bright nickel base was deposited on copper substrates using electrodeposition technique, before spraying the paint. m.a. estrella gutiérrez et al. (2016) [16], studied the effect of nickel interlayer between the copper base metal and black nickel as absorber surface as compared with black nickel directly coated on copper. the aim of this study is to implement an efficient solar selective coating based on nano-thin film combined with multilayers (ni and ag), to be employed in thermal energy application, whereas the electroplating of bright nickel is working as an interlayer between the copper substrate and copper nanoparticles (cunp) selective absorber. in addition, the effect of this layer on the optical and thermal properties has been reported; also, silver electroplating has been carried out as a second layer on the nickel layer. this nickel layer coating has slightly lower thermal absorption and emissivity than copper nanoparticles coated onto copper directly. coatings based on bright nickel and silver deposited on copper substrates using a watts bath performed has evolved the optical and physical properties as compared with the nanocoatings directly deposited onto the substrates of copper, or on the copper covered with an electroplating bright nickel. 2. experimental part 2.1 substrate preparation copper substrates cut like rectangular with dimensional (20 mm × 200 mm × 3 mm) using band saw machine type knuth german manufacturing, and in order to hang the samples in an electroplating bath, it should have a drill about (5mm). fig. (1) shows the geometry of the samples. fig. 1. copper substrate alloys pre-sample cutting. later copper substrates post cut carried out with dimensional (20 mm × 20 mm × 3 mm), as present in fig. (2). in order to use the samples in a vacuum chamber of the evaporation system, wire cutter machine type knuth was used to make the samples more suitable. mohammed j. kadhim al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 7083 (2019) 72 fig. 2. copper substrate alloys post-sample cutting. 2.2 chemical analysis of the substrate alloys the chemical composition of the copper substrate alloy has been analyzed with a spectrophotometer at the condition of temperature with 20˚c, and the humidity of 62% the chemical analysis was carried out using by using optical emission spectrometer (oes) type (foundrymaster x pert) s.n 52q0089 german manufacturing. the results of the analysis have been illustrated in the tables (1), which include the actual measured and standers values, while fig. (3) shows the microstructure of copper under an optical microscope. fig. 3. microscopic structure of copper substrate. table 1, the actual chemical compositions of copper. chemical composition% standers values actual values cu min.99.3 99.330 fe 0.10 0.142 si 0.015 0.040 0.496 p 0.000 pb 0.001 0.005 0.001 ag min. 0.027 0.019 mn 0.005 0.012 0.007 on the other hand, copper nanoparticles used as raw nanomaterial absorber was present with a mean particles size of 24 nm. table 2 gives the general specifications of cunp and the physical properties of copper powder; it was fabricated by nanjing nanotechnology co. ltd. table 2, specifications of copper nanoparticle. property the value units average particle diameter 24 nm purity 99.98 % bulk density 0.46 g/cm3 true density 4.23 kg/m3 color black 2.3 preparation for electroplating process before employing the copper substrates pieces into the chemical bath of electroplating system, the substrates were prepared for coating. the impurities, contaminants, dust, grease and other stranger particle remain from manufacturing operations must have been removed. it may sometimes require removed layer in order to achieve free surface like remove the oxides this will lead surface ready for the electroplating process. in this work, different techniques carried out to prepare the copper substrate for nickel electroplating to have flowed with silver electroplating electropolishing, ultrasonic cleaning, alkaline cleaning, acid clearing, cleaned and polishing as illustrative in fig. (4). mohammed j. kadhim al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 7083 (2019) 73 fig. 4. scheme represented the surface methods achieved in this study. 3. bright nickel electroplating bright nickel deposited on copper substrates as interlayer carried out by electroplating technique. the bright nickel layer was achieve using the plating cell rectangular shape with size (50 liters) containing (niso4.6h2o 240 g/l, nicl2.6h2o 20 g/l, h3bo3 20 g/l and with different concentrations of kno3) as electrolyte solution sometimes called watts bath. while the plating bath was made from polyphenols chloride (pvc), nickel sheets with dimensions (25× 25×3) cm were used as the anode, while copper pieces with dimensions (20 × 2× 0.3) cm used as the cathode. before each run, the nickel plating sample preparation carried out. a d.c power supply unit supplied direct current. however, the conditions of coating applied current density (2.4-2.8) amp/dcm2 and coating time (0.5-1) minute, the electroplating process conditions are listed in the table (3). table 3, nickel electroplating process conditions. electroplating condition standard parameter actual parameter temperature of electroplating 50 60°c 53°c p.h of electrolyte 3.5 5 4.8 size of bath 50 liters sample size 20cm x 2cm period of electroplating max. 30 min. 0.5-1 min. number of anodes at least 2 2 area of anodes double cathodes area at least 2 (625 cm2) area of the cathode (sample) less than anodes area 40 cm2 the cathodic current efficiencies cce high 89% nickel bath type watts bath commercial watts bath range of anode and cathode minimum 2.5cm 25 cm mohammed j. kadhim al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 7083 (2019) 74 while the second stage represented by silver layer has been obtained via electroplating with the conditions displayed in table (4). they have been firstly immersion in glass bath containing 2 liters consist of silver cyanide 1 g/l, bicarbonate sodium 20 g/l and silver nitrate 1 g/l at warm temperature 40ºc, and 2.5 adcm2 for (30 sec) to obtaining the desired thicknesses. table 4, silver electroplating conditions. electroplating conditions standard parameters actual parameters temperature of electroplating 38 50ºc 40ºc current density 0.5-10 amp/dcm2 2.5 amp/dcm2 ph. 3.5 5 4.8 baths size 2 liters samples size (20 x 2) cm electroplating time max. 37 min. 2 min. area of anodes to the cathode 2 -1 2(4 x20 x0.9 cm) the cathodic current efficiencies cce% mid-high 70% anode type ag regular grade commercial, s.s 304 type of bath sliver cyanide bath commercial cyanide bath anode and cathode distance minimum. 2.0 cm 3 cm 4. thermal evaporation preparation procedure thermal evaporation, which is a kind of physical vapor deposition system that has been presented in fig. (5), is used to obtain a thin film. prior to placing the substrates inside the vacuum chamber, the substrates were prepared for coating material into the boat made from molybdenum, the substrate pieces were cleaned and polished in order to remove the dust, grease, and other strange particles, and the vacuum chamber was evacuated to a 2.5×10−4 pa base pressure, as presented in table (5). table 5, evaporation and melting temperatures of cunp vapor pressure, mbar. melting temperature, c ° density bulk g/cm3 metal 5-10 4-10 3-3.7 1.1-2.7 1083 0.46 copper (cu) the process started with weighed of powder nanomaterials to be filled it into molybdenum boat, and placed at the center of the champers. the evaporating of copper powder nanoparticles begin by heating the boat through the control of the current and voltages smoothly and gradually to get a uniform deposition rate resulting in a thin film of copper. the deposition process used in this work carried out by the pvd system consists of units, as shown in fig. (5). mohammed j. kadhim al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 7083 (2019) 75 fig. 5. thermal evaporation unit using in study. fig. 6. photo images of coated samples; (a) cu-cunp (b) cu-ni-ag-cunp (c) cu-ni-cunp and (d) si-cunp. 5. results and discussion 5.1 x-ray diffraction result x-ray diffraction (xrd) spectrum of the cu with cu ka radiation (e=1.0454a°) at a scanning rate of (10 deg. per sec) and angle (ɵ) ranging from 20 to 80, fig. (7) shows the x-ray patterns of crystalline structure of the copper substrate, cuni, cu-ni-ag and copper nanoparticles (cunp) combined with ni-ag from bottom to top, respectively. black lines diagram indicted the strong peaks at angles 43.4029o and 50.4952o, and 74.1857o corresponding to the copper substrate without coatings [7], while the green color shows peaks and presence of nickel that plated on copper substrate demonstrated at peaks 49.7181o with structure (200) regarding to xrd card number 451027, on the other side sliver revealed in diagram blue color at peak 44.3887o with structure (200) (xrd card number 04-0783). fig. (6) displays with a red color showing nano-copper thin films strong peaks at angles, 43.2435º, 50.3690 º, 74.0647 º with structure (1 1 1) (2 0 0) and (2 2 0), respectively according to xrd card number 04-0836, moreover, the indicated nanostructure of cunp is in agreement with t. thirugnanasambandan [17]. these results are stated according to xrd standard numbered cards issued by the joint committee on powder diffraction standers (jcpds), as the cards of diffraction depicted these result. a b c d mohammed j. kadhim al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 7083 (2019) 76 fig. 7. x-ray diffraction pattern ni, ag, and cunp deposited on copper. 5.2 energy dispersion x-ray fluorescence (ed-xrf) results ed xrf result calculating the composition of thin films with micro multilayers, were investigated quantitatively and qualitatively. they exhibited the percentage of elements that are composed thin film combined with ni-ag, strong peak belongs to the copper, nickel and silver as illustrated in fig. (8), while this test was strong evidence of the presence of nanoparticles belong to copper deposited directly on a pure silicon substrate with orientation (111) as shown in fig. (9). fig. 8. thin film ed-xrf analysis of elements (ni, cu and ag). in te n si ty ( a .u ) 2 theta (°) mohammed j. kadhim al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 7083 (2019) 77 fig. 9. thin film ed-xrf analysis of cunp coated on si. 5.3 scanning electron microscope (sem) the results pointed to the topography of the films prepared by this method more uniform as compared to the topography that prepared by other methods. it’s clear from two fig. (10) and fig. (11) obtained by the scanning electron microscope and field emission scanning electron microscope (fesem) with a magnification force of (1000 x and 2٠ kx), for figs. (10 and 11), respectively, that the analysis of surface belongs to copper thin film prepaid by thermal evaporation appear as a dense layer of small, semi-spherical nanoparticles and distributed uniformly over the sample surface area. the presence of bright nickel layer on the surface metal substrate, which acts as an intermediate layer in addition to a good surface finish has been obtained, that will affect the characteristics of the surface morphology. this, in turn, will give uniformity and homogeneity for thin film nanoparticles as compared with the coating of copper nanoparticles directly deposited on the base metal as in fig. (11). mohammed j. kadhim al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 7083 (2019) 78 fig. 10. sem image of surface cunp deposited on cu. fig. 11. fesem image of surface copper nanoparticles deposited on bright nickel-copper substrate. 5.4 atomic force microscope (afm) analysis the surface roughness and topographies of the prepared thin films were examined by afm. fig. (12) shows the afm images of the 3d surface belong to cunp thin films that were prepared by thermal evaporation as a function to the coating time. from the topographic results, it can be noted that the substrate preparation and time coating plays an important role affected by both grain size and average surface roughness as present in table (6) that shows the values of grain size, average surface roughness, and root mean square values for copper thin film prepared with different thickness. it was found that the average surface roughness of 1.19 nm and average grain size of 102 nm are optimum surface data due to the improvement of the solar thermal absorber output performance. it is concluded that increasing thickness as a result of increased coating time, lead to an increment in roughness values. the fig. (13) demonstrated the distribution chart of copper grain thin film surface with average 102 nm. mohammed j. kadhim al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 7083 (2019) 79 fig. 12. the 3d surface topography of copper nanoparticles thin film with different coating times (a) 4 min, (b) 2 min. table 6, grain size distribution and roughness data values of copper thin film. grain size (nm) average roughness (nm) root mean square (nm) coating time (min) thin film thickness(nm) 24.40 0.822 1.23 2 50 39.63 0.959 1.73 2 50 102 1.19 1.94 4 100 fig. 13. grains size distribution chart along thin film surface area examined. 5.5 thermal conductivity using hot disk equipment (thermal constant analyzer) type keithley, tps-500 two side sensor with conditions parameters temperature 23.0 ºc, out power 2 watt, and measurement time (5sec). this was achieved to study and evaluate the thermal conductivity behavior of copper mohammed j. kadhim al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 7083 (2019) 80 nanoparticles and influencing of bright nickel and silver on thermal properties. it was found that a slight decrease in thermal conductivity occurred, while thin film of nanoparticles exhibited a good enhancement in thermal conductivity, which led to a good improvement in absorption by the data shown in table (7), and also a good enhancement with the presence of copper nanoparticles as compared with copper nanoparticles combined with bright nickel and sliver [18, 19]. table 7, thermal properties of different samples used in this work. samples thermal conductivity, w/m.k thermal diffusivity, mm2/s specific heat, mj/m3.k cu 3.392 0.0083 4.840 cuni -cu np 5.213 6.427 0.8111 cuni-ag-cu np 4.268 0.6642 6.426 cu-cu np 6.426 0.9874 6.026 5.6 optical properties solar selectivite coating depends on the optical properties, hence the increase in general absorption is a result of increasing the thickness of thin film. this is due to the increase in the degree of crystallization caused by increasing the thickness. this will lead to increase in the particle size hence, the incident photon on the thin film surface, which will suffer from sequential absorption done by the crystals in the same particles and, therefore the possibility of reflection or transmission will decrease, primarily by increasing the particles size. on the other hand, this may obtain higher roughness causing efficient absorption, and this agrees with researchers j. el nady et al. [15] and m. a. estrella [16]. the higher thickness of the thin films, resulting in greater absorption. fig. (14) showed a comparison between the behavior of the absorption spectrum of copper nanoparticles as a function of thickness, it was found a high absorption in the wavelength range from 300-1100 nm to reach the maximum value of 93.191%, while the bright nickel and silver layers combined with cunp deposited on copper, caused a slight decreases in thermal absorption. the presence of bright nickel and sliver reduced these values to 87.73%, 86.50%, respectively, which were concerned with the researcher stefano pratesi [20]. fig. 14. the spectral absorption in the uv-vis region for copper nanoparticles prepared with different thickness. 6. conclusion according to the results achieved cunp, it revealed a good optical and thermal properties, the obtained thermal absorption was approximately equal to (93.191%), while ni and ag layers combined with cunp are considered an excellent choice to avoid the diffusion of the copper thin film nanoparticles toward the copper substrate, good thermal stability and reducing the thermal emissivity. slight decrease was observed, in the optical absorption of the coatings of about (87.73% and 86.50%) with bright nickel and silver layers gathered with cunp, respectively. thermal conductivity has been improved, when compared with copper substrate alone, whereas the copper nanoparticles exhibited excellent improvement of about 89.44%. on the other hand, slight decrease in thermal conductivity of about mohammed j. kadhim al-khwarizmi engineering journal, vol. 15, no. 3, p.p. 7083 (2019) 81 18.87% was observed in the presence of ni layer. these characteristics that have been obtained are desirable and can be regarded as an improvement of the performance of the efficient solar absorber. 7. references [1] yuyi yang, “the study of nanostructured solar selective coatings”, msc.thesis. electronics engineering university of york, march 2012. 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[online]. available: https://doi.org/10.1155%2f2014%2f834128 )2019( 7083، صفحة 3، العدد15دجلة الخوارزمي الهندسية المجلم محمد جاسم كاظم 83 نحاس والمرسب على حبيبات ال، على معدن النحاس ألطالء الكهربائي المتعدد الطبقات من النيكل والفضة الماصةسطوح في ال والمستخدم النانوي ***سلوم عباس أحمد **خالد عجمي سكر *محمد جاسم كاظم بغداد / العراق /الجامعة التكنولوجية /عادنمقسم هندسة االنتاج وال*،*** بغداد / العراق /الجامعة التكنولوجية /قسم الهندسة الكيمياوية ** yahoo.com1957alimohammed@ *البريد االلكتروني: 150001@uotechnology.edu.iq :البريد االكتروني** ahmedsaoom@yahoo.com :البريد االلكتروني*** الخالصة لذي وا cunpحبيبات النحاس النانوية غشاء رقيق من على الكهربائي، الطالء بطريقة والفضة الالمع النيكل طالء إضافة تأثير دراسة تمت العمل، هذا في اللماع طبقات النيكل وجود أظهر بينما ، النحاس النانوي بوجود الغشاء في قيم االمتصاصية "تحسنا أظهرت النتائج .الحراري التبخير طريقة عبر رسب ٪) ٨٧ إلى٪ ٩٣( من طفيف بشكل )واالنبعاثية الحرارية االمتصاصية،( البصرية الخواص االنخفاض في كما لوحظ أيضا. ةالحراري ثباتيةل "اتعزيز والفضة بالقرص التحليل باستخدام تقنية الحرارية التوصيلية تقييم تم ، أخرى ناحية من٪). ٨٦٫٥٠( حوالي االمتصاص على طفيف اخر تأثير للفضة كان بينما ، في٪ ١٨٫٨ بنسبة انخفض حين في ،٪) ٨٩( حواليب المرسب على النحاس مباشرة cunp بوجود غشاء حصل جيد تحسن النتائج وقد بينت ،)tps(الساخن تقنية حيود االشعة السينية باستخدامالخرى امع طبقات الطالء النانوي االطوار للغشاءالبنية وكما تم دراسة التراكيب و cunp اللماع النيكل وجود طبقة (xrd) ، المجهر االلكتروني الماسح باستخدام السطح وخشونة طبوغرافية عالوة على دراسة )(sem ومجهر القوة الذرية )afm(. this is an open access article under the cc by license : al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 21, no. 4, december, (2025), pp. 136-144 effect of fibre loadings on the tensile properties of palf/phbv composite: a twoparameter weibull analysis zaleha mustafa1*, ain sappa amirah2, siti hajar sheikh md fadzullah3, yan yan farm4, thanate ratanawilai5 1,2 faculty of industrial and manufacturing technology and engineering, universiti teknikal malaysia melaka, hang tuah jaya, 76100 durian tunggal, melaka, malaysia 3 faculty of mechanical technology and engineering, universiti teknikal malaysia melaka, hang tuah jaya, 76100 durian tunggal, melaka, malaysia 4 faculty of engineering, universiti malaysia sabah, jalan ums, 88400, kota kinabalu, sabah, malaysia. 5 department of industrial and manufacturing engineering, faculty of engineering, prince of songkla university, hat yai, 90110 songkhla, thailand *corresponding author’s email: zaleha@utem.edu.my (received 22 july 2025; revised 8 november 2025; accepted 10 november 2025; published 1 december 2025) https://doi.org/10.22153/kej.2025.11.006 abstract interest in biodegradable and sustainable is steadily rising which has made the investigation into natural fibre reinforced biopolymers. among these, poly(3-hyroxybutyrate-co-3-hydroxyvalerate) (phbv) stands out for its biodegradability and biocompatibility, but its inherent brittle and has few or no properties conducive to application to wider engineering fields. additionally. the natural variability of fibres can lead to inconsistent mechanical performance, yet only a few studies have examined this variability from a statistical perspective. in this study, the influence of adding pineapple leaf fibres (palf) at different loading (10-40 wt.%) was investigated on the mechanical behaviour of phbv. the tensile strength was analysed using a linearized two-parameter weibull method to determine the scale (η) and shape (β) parameters, providing insight into both the typical strength and the variability of the composite’s performance. the results show that tensile strength increases with fibre loading, with highest of 46.54 mpa (±4.12) at 30 wt.% palf, corresponding to a 73% rise in scale parameter compare to other loadings. a strong correlation was established between the experimental data and the weibull model, with (r2 > 0.9) and the differences are below 1 % and 7 % for neat phbv and palf/phbv respectively. scanning electron microscopy (sem) analysis revealed signs of fibre rupture and fibre extraction, indicating that the composite’s failure was a result of poor interfacial bonding between the matrix and fibre. the weibull analysis able to provide more comprehensive evaluation of the composite mechanical reliability as it taken account the statistical distribution of all measured data rather than just the means value. the two-parameter weibull model demonstrated that the composite containing 30 wt.% palf attained the maximum tensile strength with satisfactory reliability. this finding signifies an ideal equilibrium between performance and variability, essential for the dependable design of sustainable phbv-based composites. keywords: tensile strength; palf; fibre loadings; weibull distribution; phbv polymer 1. introduction growing concerns on the impact of the consumer products on the environment are shifting interest to use more sustainable and environmentally friendly source. materials such as natural fibre reinforced composites and degradable polymer offer potential solution because of their ability to decompose mailto:zaleha@utem.edu.my https://doi.org/10.22153/kej.2025.11.006 zaleha mustafa al-khwarizmi engineering journal, vol. 21, no.4, pp. 136144 (2025) 137 and their mechanical properties alf, an agricultural by product presents significant potential as a degradable reinforcement characterized by outstanding mechanical properties and renewability. [1]. this is attributed to its high cellulose content and lowdensity attribute. when palf used in degradable polymer matrix system, such as polylactic acid (pla), poly(3-hydroxybutyrate-co-3hydroxyvalerate) (phbv), poly (butylene succinate) (pbs), it is capable to enhance the mechanical performance of the resulting composite as along with retaining the degradability properties [2]. hazwani et al. [3] indicated that incorporating palf into the epoxy resin matrix significantly enhances the tensile properties of the composite. the performance of composites based on palf can be further improved when combined with synthetic fibres like kevlar [1] suggesting that palf is excellent reinforcement option when both mechanical strength and suitability are essential. phbv is a thermoplastic polymer synthesized by microorganisms. it demonstrates superior biodegradability, but possesses only moderate mechanical strength. phbv is widely used in packaging, agricultural and biomedical applications because of its renewable origin and environmental compatibility. however, one of the shortcomings of the phbv is its inherent brittleness [4]. therefore, in order to enhance its mechanical performance, phbv can be bounded with more ductile polymers or combined with a natural fibre such as palf, bast, kenaf, diss and other natural fibres exhibit a significant enhancement in mechanical properties [5-8]. although there maybe challenges in combining a hydrophilic fibre with the phbv polymer matrix, the overall improvement in mechanical performance of the resulting composite would depend on variables such as fibre contents, dispersion and interfacial bonding [9]. poor interfacial bonding between natural fibre and phbv polymer is due to their polarity mismatch. natural fibre such as palf are hydrophilic in nature, while phbv is a more hydrophobic material. therefore, it prevents good compatibility during fabrication, resulting in poor bonding at the matrix and fibre interface and may weaken the resulting composite produced [10]. at the same, phbv is quite sensitive to thermal degradation provided only a small processing window and prevent thorough blending or melt mixing during fabrication. this will reduce the efficiency of the fibre-matrix interaction and consequently the mechanical performance [11]. thus, usage of proper surface treatment is crucial in order to ensure better compatibility and stronger bonding between matrix and fibre [10]. to enhance material polarity and eliminate surface impurities, this study used an alkaline surface treatment. all palf was treated with a 5 wt.% sodium hydroxide (naoh) aqueous solution, specifically prior to composite fabrication. composites materials made from natural fibre, such as palf which have higher variability in their properties compare to synthetic materials due to their inherent characteristics. as a result, it is critical for the researchers and designer to properly understand and quantify this variability in order to ensure their reliability in practical applications. statistical method, such as weibull analysis, are commonly used in reliability engineering to analysis the failure probability and variability material properties. the two-parameter weibull distribution can provide valuable information into the statistical distribution of material properties [12]. therefore, this enables researchers to estimate the failure probability and consistency of the materials performance under varying conditions or stress loads [13-14]. djeghader et al. [15] utilized the weibull analysis to evaluate the reliability of jute/polyester composites. on the other hand, aziz et al. [16] applied the same approach to evaluate the performance of uhmwpe composite laminates. however, the application of weibull reliability analysis to palfbased composite systems remains limited. most of the studies highlighted the surface treatment effect, fibre loadings, or processing conditions on average mechanical properties with few addressing the statistical reliability and variability under loading utilizing probabilistic models like the weibull distribution. thus, the objective of the present work is to evaluate the mechanical performance of the palf/ phbv composite by varying its fibre loading from 10 to 40 wt.% and to predict the influence of fibre loading on the weibull distribution. the experimental tensile strength data were analysed using a two-parameter weibull distribution to assess the reliability and predict the composite mechanical performance. the theoretical values were calculated by linear curve fitting of the weibull model and the correlation between the estimated and experimental results was examined. the outcome of this study is expected to provide insight into the contribution of natural fibres in bio composite in general, aiding in the prediction of their variability and providing a better reliability model for their properties to facilitate the development of high performance and eco-friendly materials for engineering applications. zaleha mustafa al-khwarizmi engineering journal, vol. 21, no.4, pp. 136144 (2025) 138 2. materials and methods the matrix used in this study is a thermoplastic phbv (enmat y100p), purchased from tianan biopolymer (china). it contains 3% molar content of 3-hydroxyvalerate (hv), a density of 1.25 g/cm3, a melt flow index of 5.2 g/10 min and a melt flow window of 170-180 ºc. pineapple leaf fibre (palf) (serat alfibre, west java, indonesia), with a density of 1.52 g/cm3 was used as a reinforcement. sodium hydroxide and chloroform, each with a purity of 99.99% (laboratory grade), were purchased from merck and co. and used as solvents. 2.1 composite production the palf was alkaline-treated with a 5% naoh aqueous solution (w/v) before fabrication. after treatment, the fibres were cut into 6 mm using a precision paper cutter. to ensure consistency, random samples of the cut fibres were observed under an optical microscope the length variation was about ±0.5 mm. the palf fibres were made into a thin film using a paper-making method and stored in a drying cabinet until needed the phbv pellets were dried in an oven at 60 ºc to eliminate a moisture. a 5 wt.% phbv solution (w/v) was prepared via dissolving them in chloroform. palf films were dipped into the phbv solution for coating and then dried in a vacuum oven at 60°c overnight to ensure the solvent was completely removed. the pre-pregs palf and plain phbv films were stacked and compression moulded at 175°c, as shown in figure 1. the composites were made with different palf contents, namely 10,20,30, and 40 wt.%. using preimpregnated palf film helped to ensure proper fibre alignment and consistent infiltration within the composite. because of the narrow processing temperature range, high-temperature and high-shear methods, such as extrusion or injection moulding, can lead to thermal degradation. to avoid this, low temperature solution casting and hot-pressing method have been used in this study, to preserve the integrity of phbv and improve fibre wetting. details about the alkaline treatment, pre-pregging parameters, and fabrication process can be found in previous publications [5]. fig. 1. preparation and fabrication processes of palf/phbv composites 2.2 tensile tests the tensile properties of palf/phbv composites were measured using a 20 kn universal testing machine (ags-x shimadzu, japan) following the astm d3039 standard. the tests were conducted at a crosshead speed of 2 mm/min on samples with 20 ± 0.1 mm x 3 ± 0.1 mm dimensions with a gauge length of 80 mm. the samples were manually secured using serrated mechanical grips without using the end tabs. the applied force (n) and elongation (mm) were zaleha mustafa al-khwarizmi engineering journal, vol. 21, no.4, pp. 136144 (2025) 139 recorded. five samples were tested for each fibre loading condition, and the reported average value. all samples were conditioned under controlled conditions of 23 ± 3ºc and 50 ±10% rh. 2.3 weibull distribution in this study, a two-parameter weibull statistical analysis was applied to evaluate the variability in tensile strength of palf/phbv composites at different fibre loadings. the cumulative distribution function of the two-parameter weibull distribution is expressed by equation 1 [5, 14,16]. 𝐹 = 1 − e (− 𝜎 𝜂 ) 𝛽 … (1) where f is the cumulative density probability function (failure probability) at a tensile stress, σ, while η is the scale parameter (weibull strength); and β is the shape parameter (weibull modulus), which can be written in the form of a linearized equation (equation 2) [5,14,16]. ln [ln 1 1−𝑃 ] = 𝛽 ln(𝜎) − 𝛽 ln(𝜂) … (2) the weibull parameters specifically (shape, β, and scale, η) were determined using the linearized probability plotting method which applies leastsquares regression of the transformed weibull equation. parameters’ shape and scale were derived from the slope and intercept of the linear regression. the accuracy of fit was evaluated through the coefficient of determination (r2). the cumulative probability density is expressed in terms of the median rank formula [5,14,16] as given by equation 3: p = i-0.3 n + 0.4 … (3) here, € and n denote the current test number and the total number of tests in each set, respectively. 3. result and discussion 3.1 tensile properties of the composites the neat phbv and palf/phbv composites with different fibre loadings were tensile tested until fracture (figure 2). all the samples fractured within the gauge length. the tensile property values are shown in figure 3. the addition of palf loadings from 10 to 40 wt.% improves the tensile performance of the palf/phbv composites. statistical analysis conducted using a one-way anova indicated that the incorporation of palf into the phbv matrix significantly (p<0.05) enhanced the tensile properties of the bio composite. the maximum tensile strength and modulus of elasticity were achieved with the addition of 30 wt.% palf, yielding 46.54 (± 4.12) mpa and 10.36 (± 0.81) gpa, respectively. the improvement in the tensile strength and modulus is due to effective stress transfer between the palf and phbv matrix [2, 9, 17]. observation of the fractured surface of 30 wt.% palf/phbv composite (figure 4) shows fibre fracture extending across the surface of cracks, commonly referred to a fibre bridging. this shows the composite can withstand stress prior to failure, improving its tensile strength and underscoring the effective role of the reinforcement in transferring load. these findings are consistent with earlier reports that highlight the mechanical benefits of palf reinforcement due to its high cellulose content and effective stress transfer within the matrix [18]. fig. 2. fractured specimens of palf/phbv composites with different fibre loadings (a) unfilled, (b) 10 wt.%, (c) 20 wt.%, (d) 30 wt.% and (e) 40 wt.%. zaleha mustafa al-khwarizmi engineering journal, vol. 21, no.4, pp. 136144 (2025) 140 fig. 3. influence of fibre loadings on tensile properties of palf/phbv composites fig. 4. tensile fracture morphology of the palf/phbv composite containing 30 wt.% fibre loading 3.1 weibull distribution in this study, a two-parameter weibull distribution was used to analyse the effect of the fibre loading on the phbv and palf/phbv composite performance. the scale (η) and shape parameter (β) for the phbv and its composite were determined using equation 2, in addition to the corresponding strength values through a linear curve fitting. the weibull plot parameters for the palf/phbv composite in terms of tensile strength with varying fibre loadings are shown in figure 5. for each fibre loading, a total of 5 samples were subjected to testing. the correlation coefficient (r2) values were calculated for each of the fibre loadings, all of which exceeded 90%. these high correlation values indicate a strong agreement between the experimental data and the fitted curve, as the previous study presented similar findings [16]. table 1 shows the range of the weibull modulus values for all fibre loadings. the weibull modulus (β) or shape parameter is indication of the degree of data variability. a higher value of shape parameter means the results are more uniform, while lower value indicates a wider variation in strength [5,14]. in this study, neat phbv showed a relatively high modulus (β = 29.28), which point out to more consistent mechanical behaviour. on the other hand, the palf/phbv composites recorded lower β values, with the 40 wt.% palf/phbv sample produced the lowest (β = 6.14). this wider scatter probably due weak fibrematrix bonding and uneven stress transfer within the composite [19, 20]. as fibre loading increased, the palf layers become thicker, and this may hinder proper wettability during fabrication. the phbv matrix might then fail to penetrate fully between the fibres, leaving voids or weak regions that reduce stress transfer efficiency. from the sem images (figure 6), fibre pull-out and debonding can be clearly seen, with little matrix residue on the fibre surface, which support this observation. some of the variation could also be related to the inherent variability of the palf itself. a trade-off seems to be between improving tensile strength and maintaining reliability in the composites. the 30 wt.% palf sample has showed the highest tensile strength, likely due to the effective transferring between fibre and the matrix. on the other hand, its lower weibull modulus (β) indicates that the failure was less consistent variability might arise from uneven wetting or local stress concentrations when fibre loading becomes excessive. although data on β values for phbv based composite is quite limited, studies on other natural fibre systems have supported this finding. for example, wand and shao [21] reported β value ranging from 2 and 6 for bamboo fibre composites. as a result, this considerable variability has often been seen in natural fibre-based materials. having compared the 30 wt.% palf/phbv samples, this study showed a β value exceeding 10 indicated much higher reliability. this is likely to reflect the positively effect of fibre treatment and fabrication method approach in improving both consistency and overall mechanical performance in general, nature fibres have higher variability in mechanical properties comparing with synthetic fibres, due to inherent flaws and irregularities. due zaleha mustafa al-khwarizmi engineering journal, vol. 21, no.4, pp. 136144 (2025) 141 to inherent flaws and irregularities of the high variability of nature fibres. the composite performance can be strongly impacted, reducing reliability and making failure behaviour are more difficult to predict. adding more fibre can raise the risk of uneven distribution and inconsistent matrix– fibre bonding this variability is responsible for the wider scatter in tensile strength observed in the palf/phbv composites. in this study, the observed variation in tensile strength is determined as a result of the natural differences in palf fibres, such as their diameter and overall structure. given that the palf film were produced using a paper making technique. the fibre may not be effectively distributed, which can introduce potential weak points. consequently, careful control over fibres processing and uniform dispersion is necessary to produce stronger and more consistent composites. table 1 shows that the theoretical mean tensile strength values agree closely with experimental measurements. for the neat phbv, the difference between theoretical and experimental values was less than 1%, while the palf/phbv composites was about 7%. fig. 5. the weibull lines for palf/phbv composites at different fibres loadings table 1, the weibull parameters of the palf/phbv composites at different fibre loadings. fig. 6. tensile fracture of the 40 wt.% palf/phbv composite 4 conclusions this study highlights the clear impact of adding palf to the phbv matrix on the composites’ tensile strength and modulus. as the fibre content increased, both properties improved, peaking at 30 wt.% palf with tensile strength and modulus reaching 46.54 mpa and 10.36 gpa, respectively. interestingly, the weibull analysis showed that these gains came with greater variability. in general, the palf/phbv composites had lower weibull moduli, with the 40 wt.% palf sample showing the lowest at β = 6.14. this increased variation is likely linked to weaker fibre/matrix bonding and the inherent irregularity of the palf. at the same time, the scale parameter increased by 73% for the 30 wt.% composite compared with other loadings. sem examination supports these observations, revealing both fibre pull-out ad breakage which palf loading (wt.%) weibull strength, η (mpa) weibull modulus, β experimental strength, σ (mpa) (± s.d) percentage of error (%) neat phbv 27.22 29.28 27.30 (±0.58) 0.31 10 29.74 15.66 28.29 (±2.20) 2.85 20 29.86 21.06 29.82 (±0.75) 0.11 30 48.57 10.43 46.54 (±4.12) 4.18 40 47.11 6.14 43.89 (± 6.41) 6.83 zaleha mustafa al-khwarizmi engineering journal, vol. 21, no.4, pp. 136144 (2025) 142 suggest that the matrix/fibre interface was not fully bonded. in summary, while adding palf may enhance tensile performance, achieving more uniform bonding and consistent reliability remains 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[21] f. wang and j. shao, “modified weibull distribution for analyzing the tensile strength of bamboo fibers,” polymers, vol. 6, no. 12, pp. 3005-3018, dec 2014, doi:10.3390/polym6123005. https://doi.org/10.1016/j.jcomc.2024.100549 zaleha mustafa ( 2025) 136-144، صفحة 4، العدد21مجلة الخوارزمي الهندسية المجلد تحليل :palf/phbvتأثير احمال االلياف على مقاومة الشد للمواد المركبة المقواة بألياف ويبل ثنائي المتغيرات zaleha mustafa1*, ain sappa amirah2, siti hajar sheikh md fadzullah3, yan yan farm4, thanate ratanawilai5 ، ماليزيا مالكاغال، دوريان تون 76100، هانغ تواه جايا، مالكا، الجامعة التقنية الماليزية الهندسة الصناعية وتكنولوجيا التصنيع كلية 1،2 ، ماليزيا مالكاغال، دوريان تون 76100، هانغ تواه جايا، مالكا، الجامعة التقنية الماليزية تكنولوجيا الميكانيك والهندسةكلية 3 .، كوتا كينابالو، صباح، ماليزياums ،88400شارع كلية الهندسة، الجامعة الماليزية صباح، 4 سونغكال، تايالند 90110قسم الهندسة الصناعية والتصنيع، كلية الهندسة، جامعة أمير سونغكال، هات ياي، 5 zaleha@utem.edu.my اإللكتروني:البريد * المستخلص الطبيعية. من بين هذه يتزايد االهتمام بالمواد القابلة للتحلل الحيوي والمستدامة بشكل مطرد، مما دفع إلى البحث في البوليمرات الحيوية المقواة باأللياف ( بولي يتميز بيوتيرات-3البوليمرات، فاليرات -3-كو-هيدروكسي وتوافقه (phbv)هيدروكسي الحيوي للتحلل بالهشاشة بقابليته يتميز أنه إال الحيوي، اء ميكانيكي غير وخصائص محدودة أو معدومة تُمّكن من تطبيقه في مجاالت هندسية أوسع. باإلضافة إلى ذلك، يمكن أن يؤدي التباين الطبيعي لأللياف إلى أد (palf) سة، تم التحقيق في تأثير إضافة ألياف أوراق األناناسمتسق، ومع ذلك، فقد تناولت دراسات قليلة فقط هذا التباين من منظور إحصائي. في هذه الدرا ثنائية المتغيرات الخطية لتحديد weibull . تم تحليل مقاومة الشد باستخدام طريقة phbv ( على السلوك الميكانيكي لـwt٪40-10عند أحمال مختلفة ) قاومة الشد النموذجية وتباين أداء المادة المركبة. تُظهر النتائج أن مقاومة الشد تزداد ، مما يوفر نظرة ثاقبة على كل من م(β) والشكل (η) متغيرات المقياس ٪ في متغير 73، وهو ما يتوافق مع ارتفاع بنسبة palf من الياف wt٪ 30( عند 4.12ميجا باسكال )± 46.54مع تحميل األلياف، حيث بلغت أعلى قيمة ٪ أللياف7٪ و 1واالختالفات أقل من r)2 (0.9 <، مع weibullمقارنة باألحمال األخرى. تم إنشاء ارتباط قوي بين النتائج العملية ونموذج (ηالمقياس ) phbv النقية وألياف palf / phbv على التوالي. كشف تحليل المجهر اإللكتروني الماسح (sem) عن عالمات تمزق األلياف وخروج األلياف من من توفير تقييم أكثر weibull لمادة المركبة كان نتيجة لضعف الترابط السطحي بين المصفوفة واأللياف. تمكن تحليلالمصفوفة، مما يشير إلى أن فشل ا مة المتوسط. أظهر نموذجشموالً لموثوقية السلوك الميكانيكي للمادة المركبة ألنه أخذ في االعتبار التوزيع اإلحصائي لجميع النتائج المقاسة بدالً من مجرد قي weibull 30ثنائي المتغيرات أن المادة المركبة التي تحتوي على ٪wt من الياف palf مع موثوقية مرضية. تشير هذه النتيجة مقاومة شد قد حقق أقصى . phbvإلى توازن مثالي بين األداء والتباين، وهو أمر ضروري للتصميم الموثوق به للمواد المركبة المستدامة المقواة بالياف mailto:zaleha@utem.edu.my microsoft word 43-50 ??? ????? ????? ????? ?????   al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 17, no. 1, march, (2021) p. p. 4350   adsorption of indigo carmen dye by using corn leaves as natural adsorbent material omar h. fadhil* mohammed y. eisa** dina abdalrahman salih*** ziad r. nafeaa **** *department of medical laboratory technology/ college of medical science/ al-mashreq university **,***,**** department of biochemical engineering/ al-khwarizmi college of engineering/ university of baghdad *email: omarhisham.94@yahoo.com **email: mohammedyeisa@yahoo.com ***email: dina_ar6@yahoo.com ****emial: inspiron514@googlemail.com (received 26 september 2020; accepted 16 november 2020) https://doi.org/10.22153/kej.2021.11.002 abstract in this paper, the ability of using corn leaves as low-cost natural biowaste adsorbent material for the removal of indigo carmen (ic) dye was studied. batch mode system was used to study several parameters such as, contact time (4 days), concentration of dye (10-50) ppm, adsorbent dosage (0.05-0.25) gram, ph (2-12) and temperature (30-60) oc. the corn leaf was characterized by fourier-transform infrared spectroscopy device before and after the adsorption process of the ic dye and scanning electron microscope device was used to find the morphology of the adsorbent material. the experimental data was imputing with several isotherms where it fits with freundlich (r2 = 0.9937) and followed pseudo second order kinetic. the highest removal percent was equal to 91% of the dye which makes the corn leaves a suitable efficient material for the removal of ic dye from aqueous solutions. keywords: adsorption, batch, corn leaf, indigo carmen dye, isotherm, kinetics. 1. introduction the wastewater that produced from textiles, papers, food, and pharmaceutical industries contains complex organic and aromatic compounds due to the types of dyes used that may be harmful and toxic to humankind and other living creatures. the major problem of the contaminated wastewater is that it contains very low concentrations of the dyes that minimizes the quality of water resource and increase environmental concern, that is why it must be treated before disposal to the assigned places [1]. many methods are used these days for the treatment of polluted and colored wastewater. one of the common methods that widely used is adsorption due to its ease of operation, high recovery and efficiency [2]. agriculture bio-waste is used as alternative adsorbent materials for the adsorption of dyes because of its cheapness, high surface area, high removal efficiency, availability, and eco-friendly to the environment which are used for fixing environmental pollution problems. the adsorption of dyes by using biowaste adsorbents had been studied by many researchers such as the adsorption of methyl orange by corn leaves [3], aniline blue by rice husk [4] and methyl red by tree park powder [5]. omar h. fadhil al-khwarizmi engineering journal, vol. 17, no. 1, p.p. 4350(2021)   44 indigo carmine is a synthetic dye which is used as dermatological agent, biological stain and antibacterial agent. also it is a carcinogen material, recalcitrant, and very toxic to mammalian cells [6]. indigo carmen dye structure is shown in figure 1. fig. 1. structure of indigo carmen dye. the aim of this paper is to study the adsorption of indigo carmen dye by using corn leaves from aqueous solution. 2. materiais and methods a group of runs were conducted at alkhwarizmi college of engineering / baghdad university to study the effect of several parameters on the adsorption process. a sets of design of experiments were used for batch adsorption studies in which different concentrations of the dye from 10 to 50 ppm were put in 100 ml containers and mixed with various amounts of the adsorbent from 0.05 to 0.25 g/l with constant temperature (30℃) and initial ph (6.2). in the first set of experiments, containers were shaken at 150 rpm with contact time in the range (1-4) days with a step of one day. the effect of both ph and temperature was investigated using another set experiment. the ranges were (2-12) for ph and (30-60)℃ for temperature respectively. factors studied in the first set were fixed at the optimum values. the equilibrium concentrations of ic dye were determined by measuring the absorbance using uv-visible spectrophotometer (shimadzu 1800) device at a wavelength of 610 nm. the plot of absorbance vs. concentrations was observed as linear as shown in figure 2. this curve will be the standard expression of the dye concentration with respect to the absorbance recorded at 610 nm using uv-vis spectrophotometer all over the experimental work. the equilibrium concentrations and dye removal efficiency were calculated using the following equations [7]: qe = (co – ce) … (1) % removal = 100 … (2) where ce and co are the equilibrium and initial concentrations of the dye (mg/l), respectively, qe is the equilibrium dye concentration per adsorbent amount (mg/g) v is the volume of dye solution (l) m is the dosage of adsorbent (g). fig. 2. calibration curve of ic concentration vs. absorbance. the corn leaves were collected from college of agriculture engineering sciences, university of baghdad during the summer season. washed few times to get rid of dust and other impurities, then, dried in the oven at 50 oc overnight. after that, they crushed and sieved to get a particle size of 125 ϻm, then, saved in a dried containers for further use. the dye was prepared by dissolving 1 g in 1 l of distilled water to get the stock solution with concentration of (1000 ppm), then diluted to obtain several concentrations of (10-50) ppm. 3. resuits and discussion characterization of corn leaves fourier transform infrared spectroscopy (ftir) was used to characterize the corn leaves powder. the spectrum is shown in figures 3 and 4. by observing figure 3, it can be seen that the functional oh group absorption at the region of (3200-3500) cm-1 stretching vibration in phenolic and aliphatic structures. the band at (2910-2920) cm-1 is assigned to c–h stretching vibration in aromatic methoxyl groups. a peak of c=c stretch was observed at (1650-1660) cm-1 which refers to alkenyl group, also, c-o single bonds appear at around 1180 cm-1 [8][3]. omar h. fadhil al-khwarizmi engineering journal, vol. 17, no. 1, p.p. 4350(2021)   45 the change in the surface of adsorbent shows that there was an adsorption process happened during the sorption and strong interaction between ic dye and the corn leaves was predominant. the scanning electron microscopic (sem) showed the morphological picture of the corn leaves particles which is bright on the surface as shown in figure 5. fig. 3. ftir spectrum of corn leaves adsorbent before adsorption. fig. 4. ftir spectrum of ic dye with corn leaves after adsorption. fig. 5. sem of corn leaves adsorbent. effect of concentration the effect of the removal efficiency on the concentration is shown in figure 6. as the concentration increased from 10 to 50 ppm, the removal efficiency increased at the beginning, then, decreased until it reached the equilibrium point. the adsorption capacity also decreased with increasing the concentration. this can be explained to the lack of the free active sites on the adsorbent surface which is fastly reached to the saturation state. this results is matched with the results of [9] where the removal efficiency also increased then decreased until it reached the equilibrium point (91.2%) for basic violet dye. the best selected ic dye concentration was equal to 10 ppm. 5007501000125015001750200022502500275030003250350037504000 1/cm 30 35 40 45 50 55 60 65 70 %t 0 0 6 4 .9 3 0 .3 5 1 6 3 5 .6 4 1 2 7 1 .0 9 1 0 2 8 .0 6 5007501000125015001750200022502500275030003250350037504000 1/cm 10 15 20 25 30 35 40 45 50 55 60 %t 3 44 6 .7 9 3 41 4 .0 0 3 34 2 .6 4 3 2 9 4 .4 2 3 1 5 5 .5 4 2 8 77 .7 9 2 85 0 .7 9 2 83 9 .2 2 2 80 2 .5 7 2 77 7 .5 0 2 7 0 8. 0 6 2 6 9 0. 7 0 2 6 6 1. 7 7 2 6 4 6. 3 4 2 6 34 .7 6 1 6 5 8. 7 8 1 6 5 1. 0 7 1 3 90 .6 8 1 2 6 3 .3 7 3 5 72 .8 6 5 57 .4 3 5 43 .9 3 52 8 .5 0 4 9 9 5 6 omar h. fadhil al-khwarizmi engineering journal, vol. 17, no. 1, p.p. 4350(2021)   46 fig. 6 the effect of initial dye concentration on the removal efficiency of ic dye at 30 oc and contact time of 4 days. effect of adsorbent dosage the effect of the adsorbent dosage on the dye removal percent is shown in figure 7. as the dosage of corn increased, the removal efficiency increased due to the increase of the surface area of the adsorbent material. the adsorption capacity decreased as the dosage increased as the particles of the adsorbent overlapping, as demonstrated by [10] where the sorption rate of aniline and methyl orange dyes decreases in the higher dosages of aloe vera leaves waste. the best amount of adsorbent dosage was 0.25 gm for achieving the higher removal percentages of dye. fig. 7. the effects of dosage on the removal efficiency at 30 oc , 4 days contact time. effect of contact time the removal percentage of the dye was increased as the contact time increased, also the amount of dye adsorbed per unit weight of adsorbent increased. this can be explained by the formation of the driving force between dye solution and the corn leaf adsorbent that leads to high amounts of ic molecules being transferred to the surface of the adsorbent. a similar result was described by [11] where the adsorption increased with the increase of contact time for congo red dye using brewers’ spent grain. the effect of contact time is shown in figure 8. fig. 8. contact time effect on the removal of ic dye at 30 oc, 10 ppm dye concentration and 0.25 gm adsorbent dosage. effect of ph the effect of the ph on the removal efficiency is shown in figure 9. it is noticed that as the ph increase from 2 to 12, both the removal efficiency and adsorption capacity increased, this may be attributed to the surface functional groups and nature of the dye as evidenced by [12] where the amount of adsorbed crystal violet dye was found to increase with an increase in ph using walnut shell powder. fig. 9. effect of ph on the removal of ic dye at 30 oc, 4 days contact time, 10 ppm dye concentration and 0.25 gm adsorbent dosage. omar h. fadhil al-khwarizmi engineering journal, vol. 17, no. 1, p.p. 4350(2021)   47 effect of temperature figure 10 shows that as the temperature increases from 30 to 60, the removal efficiency and the adsorption capacity both decreased. this can be explained by weak bonds between the ic dye molecules and the active sites of the corn leaves adsorbent at high temperatures. the results are in agreement with [3] where both the removal efficiency and the adsorption capacity of methyl orange dye decreased using corn leaves adsorbent material. fig. 10 effect of temperature on the removal efficiency of ic dye at 30 oc, 4 days contact time, 10 ppm dye concentration and 0.25 gm adsorbent dosage. adsorption isotherm the equilibrium relationship between the adsorbent dose and the dye concentration with respect to time was depicted using langmuir and freundlich isotherms. the linear form of langmuir isotherm can be represented by the following equation [13]: ... (3) where: qe (mg/g) the amount of dye adsorbed at equilibrium qm (mg/g) the amount of dye adsorbed at saturation ce the equilibrium dye concentration (mg/l) and kl is langmuir constant. the linear form of freundlich equation is expressed as: ln 𝑞 ln 𝑘 ln 𝐶 … (4) where: kf\ and n are freundlich constants which give a measure of the adsorption capacity and adsorption intensity, respectively. (ce/qe) vs (ce) was plotted to find values of the constants (k and 𝑞 ) and the correlation coefficient (r2) as shown in table 1 for langmuir isotherm. the results indicate that the adsorption of ic by corn leaves did not match with langmuir isotherm. the data in table 1 indicates that the adsorption of ic by corn leaf as adsorbent follows freundlich isotherm. table 1, adsorption isotherm parameters for ic adsorption on corn leaves at 30oc. langmuir ce/qe = 1/klqm + ce/qm qm -5.8377 kl -7.3578 r2 0.7524 freundlich ln qe = ln kf + 1/n ln ce n -1.7117 kf 2.2109 r2 0.9264 adsorption kinetics pseudo first and second order were used to study the kinetics of ic dye on corn leaf. the pseudo first order model is expressed by the equation: ln(qe – qt) = ln qe – (k1) t ... (5) where: qe and qt are the amounts of the adsorbent (mg/g) at equilibrium and at time t (min), respectively. k1 is the rate constant of adsorption (min−1). pseudo second order equation can be expressed as [14]: t ... (6) where k2 (g/mg.min) is the adsorption rate constant of pseudo second order adsorption rate. fitting the experimental data into different kinetic models such as pseudo first and second order was performed to investigate the adsorption rate, model the process and foretell the information of adsorbent/adsorbate interaction [15]. the accordance between the model values and the experimental data was expressed by correlation coefficient (r2). adsorption kinetics was shown in figure 8 as the change in percentage of dye removal with time. value of the first order rate constant could be calculated by plotting lagergren plot of log (qe-qt) with the adsorption time (t) in a linear representation as shown in figure 11. similarly, the pseudo second order constants are calculated by plotting each of (t/qt) versus omar h. fadhil al-khwarizmi engineering journal, vol. 17, no. 1, p.p. 4350(2021)   48 adsorption time (t) as shown in figure 12 with the values of correlation coefficients (r2). fig. 11 pseudo first order plot of ic adsorption by corn leaves. fig. 12 pseudo second order plot of ic adsorption by corn leaves table 2 shows the kinetic models, their constants and the correlation coefficients. table 2, kinetic parameters values with r2 for ic adsorption. pseudo first order ln(qe-qt) = ln(qe) – k1 t qe 52.5623 k1 -1.7438 r2 0.8194 pseudo second order: t/qt = (1/k.qe)+(1/qe)t qe 16.92 k2 0.1759 r2 0.9937 based on the results, the sorption of ic dye using corn leaves adsorbent is conformed well by pseudo second order kinetic model. 4. conclusions in this study, the feasibility of using corn leaves as efficient, low cost natural adsorbent material for the adsorption of indigo carmen dye for batch study was investigated. the best conditions were 10 ppm concentration, 0.25 gm adsorbent dosage, ph of 12, temperature of 30oc and contact time of 4 days for 91% removal efficiency. it was found that as the concentration and temperature increased the removal efficiency decreased and as the dosage, contact time and ph increased, the removal efficiency increased. the equilibrium data fits with freundlich isotherm and the rate of sorption followed pseudo second order kinetics with a correlation factor of 0.9937. the results proved that the corn leaves as bio waste adsorbent are efficient and economical material for the removal of ic dye from aqueous solutions. notation ce equilibrium concentration of adsorbate, mg/l co influent concentration, mg/l ftir fourier transform infrared spectroscopy k1 rate constant of adsorption of pseudo first order, min−1 k2 rate constant of adsorption of pseudo second order, g/mgꞏmin kf , n freundlich constants, dimensionless kl langmuir constant, l/mg m mass of adsorbent, (gm) pfo pseudo first order pso pseudo second order qe the uptake of adsorbate at equilibrium, mg/g qm amount of adsorbate required to form a monolayer, mg/g qt amounts of the adsorbent at time t, mg/g sem scanning electron microscopy v volume of solution, (l) acknowledgments the authors are grateful for the department of biochemical engineering, al-khwarizmi college of engineering, university of baghdad for the permission to use all the laboratory facilities and the support materials needed in this study. omar h. fadhil al-khwarizmi engineering journal, vol. 17, no. 1, p.p. 4350(2021)   49 5. references [1] a. p. vieira et al., “kinetics and thermodynamics of textile dye adsorption from aqueous solutions using babassu coconut mesocarp,” j. hazard. mater., vol. 166, no. 2–3, pp. 1272–1278, 2009. 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[13] y. s. ho and g. mckay, “a comparison of chemisorption kinetic models applied to pollutant removal on various sorbents,” process safety and environmental protection. 1998. [14] a. e. martins et al., “the reactive surface of castor leaf [ricinus communis l.] powder as a green adsorbent for the removal of heavy metals from natural river water,” appl. surf. sci., 2013. ) 2021( 4350، صفحة 1، العدد17دي الهندسية المجلجلة الخوارزمم عمر هشام فاضل 50 امتزاز صبغة كارمن النيلية بأستخدام اوراق الذرة كمادة مازة طبيعية ** محمد يعقوب عيسى *عمر هشام فاضل ***زياد رافع نافع ***عبد الرحمن صالح يناد *قسم المختبرات الطبية/ كلية تقنيات العلوم الطبية/ جامعة المشرق جامعة بغداد **قسم الهندسة الكيميائية االحيائية/ كلية الهندسة الخوارزمي/ * **،** *، * omarhisham.94@yahoo.com :البريد االلكتروني* mohammedyeisa@yahoo.com :البريد االلكتروني** dina_ar6@yahoo.com***البريد االلكتروني: inspiron514@googlemail.com :البريد االلكتروني*** الخالصة دد تم دراسة قابلية استخدام اوراق الذرة كمادة مازة طبيعيه رخيصه الثمن ألزاله صبغه كارمن النيليه. تم استخدام نظام الدفعات لدراسة ع ،في هذا البحث ) درجة ٦٠-٣٠) والحرارة (١٢-٢الحامضية ( ،) غرام٠٫٢٥٠٫٠٥الكمية ( ،) جزء من المليون٥٠-١٠تركيز الصبغه ( ،ايام) ٤من المتغيرات مثل الزمن ( لمعرفه الشكل السطحي للمادة semقبل وبعد امتزاز الصبغه وكذلك تم استخدام جهاز ال ftirسيليزية. ورق الذرة تم تشخيص خصائصه بأتسخدام جهاز ال ٪ ٩١ويتبع المعادلة الحركية الكاذبة من الدرجة الثانية اعلى نسبة ازالة كانت freundlichوانطبقت مع isothermالمازة. النتائج التجريبية انسبت لعدة للصبغه مما يجعل اوراق الذرة مادة مناسبة وكفوءة ألزالة صبغه كارمن النيلية من المحاليل المائية. microsoft word 724-article text-2161-1-11-20201019 al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 16, no. 4, december, (2020) p. p. 4151 remote patient healthcare surveillance system based realtime vital signs qunoot n. alsahi* ali f. marhoon** ali h. hamad*** *department of computer science/ university of basrah /iraq **department of electrical engineering/ university of basrah /iraq department of information and communication engineering / alkhwarizmi college of engineering / *** university of baghdad *email:qunootalsahi@gmail.com **email: ali.marhoon@uobasrah.edu.iq **email: ahamad@kecbu.uobaghdad.edu.iq (received 16 august 2020; accepted 20 october 2020) https://doi.org/10.22153/kej.2020.10.003 abstract today many people suffering from health problems like dysfunction in lungs and cardiac. these problems often require surveillance and follow up to save patient's health, besides control diseases before progression. for that, this work has been proposed to design and develop a remote patient surveillance system, which deals with four vital signs (temperature, spo�, heart rate, and electrocardiogram ecg). an adaptive filter has been used to remove any noise from the signal; also, a simple and fast search algorithm has been designed to find the features of ecg signal such as q, r, s, and t waves. the system performs analysis for medical signs that are used to detected abnormal values. the acquire data from different sensor are sent to the base-station if it have some medical issues, otherwise new data window are taken for analysis. in addition, it generates an alarm to the physicians via ringing up mobile and sms to overcome the internet disconnected. the system has been designed to achieve precision, small size, and low energy consumption. three types of sensors have been used in this work, ecg, spo�, and temperature sensors. also, a sim800l gsm module has been used for communications, the main controller in this work is esp32 unit. keywords: remote healthcare, ecg, sp��, adaptive filter, qrs features, gsm. 1. introduction recently, health issues have increased day by day in our life, where chronic diseases such as (heart disease, lungs, hypertension) that need continuous monitoring. in addition to epidemics like (covid-19, sars), etc. constitutes great concerns for people due it often leads infection transmitted and disease spread then causing death. so like that cases need to provide telemedicine concepts including tracking and real-time monitoring to health conditions, hence they need frequent visits to clinics and hospitals[1],[2]. however, healthcare constitutes an essential and important part of life. which require an attention to the health system and making it smarter. the traditional health systems suffering from many issues such as lack of medical staff and medical equipment, in qunoot n. alsahi al-khwarizmi engineering journal, vol. 16, no. 4, p.p. 4151 (2020) 42 addition to the effort made by physicians and patients and the cost of money and time. so, smart healthcare systems prepare means of low cost and small size to surveillance an individual's health[3]. ecg measures the rhythm and rate of a pulse, also introduces indirect proof on the flowing blood to the heart [4]. besides, it gives a perfect picture of the effectiveness and activity of the individual's heart muscle. many abnormalities can be observed as the electrical signal analyzes each heartbeat. the ecg signal consists of some basic features such as p, qrs, and t, where the ecg signal can be cut into segments are pq, qrs, and stsegment as shown in fig.1. so, the period of each segment should be computed to determine the heart conditions precisely. fig. 1. structure of the ecg signals [14]. in this work, a proposed telemedicine system monitors the 3-physiological parameters of the patient's body (ecg, spo�, and temperature). these physiological parameters are analysed to notify physicians about any abnormal conditions, besides, these abnormal states are stored in a system database. the proposed system uses an alert system based sim800l gsm module to inform the physician about the abnormal status of patients. the rest of the paper is organized in the following sections. in section 2, background and related works are discussed. in section 3, proposed system design. in section 4, proposed system software design. in section 5, result and discussion. in section 6, conclusion. 2. related work studies view some papers for healthcare systems. in 2016, hossein and shaikhan [5] proposed an android application to monitor the patient's health and medical-application to show the patient's information based on nfc tags, and it utilized a web server to store patients data. in 2017 kale et al [6], proposed a system aimed to monitor the patient outside the hospital in a cost-effective manner. the system handles two vital signs (heart rate, temperature) besides track patient activity via an acceleration sensor. also in 2017 kaur and jasuja [7] proposed a system looking for heart rate and temperature using raspberry pi and iot platform, but it focuses on the cost and accuracy and discards real visualize of patient's health that requires more vital signs such as(respiratory rate and regularity ecg signal, etc.). in 2017, alamelu and mythili [8], designed the internet of health thing architecture (ioht) for a healthcare system that used wireless sensor networks in iot environment for a health monitoring system. the system consists of a source node that acts as a sensor node and a sink node represent in personal digital assistants pda. the weakness in this work is the energy consumption of health monitoring applications. in 2018, mehmet taştan [9] proposed a system to handle heart rate variability and temperature besides, a real-time location of the patient. the system sends email notification if the values exceeded normal conditions, this work dependent on the internet qunoot n. alsahi al-khwarizmi engineering journal, vol. 16, no. 4, p.p. 4151 (2020) 43 in alarm. also in 2019, shaown et al [10] designed a system that is frequently monitoring the ecg signal by using wearable sensors. where it notifies the users and physicians via email when found any malformation in ecg which makes [9], [10] useless in case of internet disconnect. in 2019, tamura [11], proposed a system to monitor blood pressure depended on the iot platform to facilitate home-based healthcare. also in 2020, acharya and patil [12], proposed a system to monitor the vital signs of people to predict their health using arduino uno and raspberry pi. 3. proposed system design generally, the proposed system is smart enough to collect vital signs from patient's body and analyzed it to predict when abnormalities occur, then alert physicians and opened a connection to send data to the basestation to save it in patient's medical record. basically, the proposed system composes of three layers that are sense layer, transport layer, and application layer as shown in fig.2 sensing layer: consists of a wearable wireless body area sensor network that responsible for data collection from the patient's body then send to be processed and analyzed in the processing unit (esp32). transport layer: represented by the communication protocols (http) that is responsible for the connection between the patient side and the server-side. application layer: this layer responsible for the system data view process. this layer is represented by the web application, which allows physicians to access and view the health conditions of their patients. fig. 2 general architecture of the healthcare system fig. 3 (a) patient-node schematic diagram, (b) patient-node hardware design. qunoot n. alsahi al-khwarizmi engineering journal, vol. 16, no. 4, p.p. 4151 (2020) 44 the system consists of hardware and software that works and interacts in synchronized with each other. 1) patient-node: the patient node composes of many units that are connected to achieve the system-required tasks. fig.3 shows a patient unit schematic diagram, these units consist of: 1.1 sensing-unit (wbsn): this unit consists of several sensors that form wearable body area sensor network (wbasn). this sensor network attaches to the patient's body to gather the physical parameters (ecg, spo_2, and temperature). this sensor network should be configured with a microcontroller to control the network jobs. 1.1.1 heart respond measurement: the ad8232 ecg monitoring sensor utilized in this work is connected with the esp32 microcontroller through an analog-to-digital converter (adc). it has 3-leads (ra: right arm, la: left arm, ll: left leg) that are fixed on the various points of the human torso as shown in fig. 4. the ecg signal processing passes via three stages shows in fig. 5: fig. 4 (a) proper placement of the electrodes, (b) ecg sensor. fig. 5. ecg signal-processing stages. in the pre-processing stage, the digital value of the built-in adc (successive approximation register 12 bit type) in esp32 microcontroller is calibrated into its original values. the following formula is used to convert the digital code into a millivolt values [13]. ecg signal in mv � ���� ���������� �������∗��� ���� �! �" #$ � …(1) where: %dc sensitivity � +,��. ��� .$/ � 0011 .+ 2134 ...(2) where adc output= ecg data in digital form, adc offset = 2060, and gain =100. .b in the filtering stage, an adaptive filter is applied to eliminate several forms of noise that distorting the shape and features of the signal [13]. ecg_adp (nt) =α* ecg_adp (nt-t) + (1-α)* ecg _raw (nt) … (3) where ecg_raw (nt) is the current value of ecg signal. ecg_adp (nt) is the filtered ecg signal. n = 1 ……….∞. α is the balance coefficient (default is 0.95). c. in the feature extraction stage, a search algorithm is applied to detect ecg signal features[13]. the basic principle of the algorithm is based on a threshold value where the upper threshold used to find r-peak while lower threshold are used to find s-peak as shown in fig.4 the following formulas are used to find thresholds: r_threshold = (max data in 1000 sample/2) …(4) s_threshold = (min data in 1000 sample/2) …(5) qunoot n. alsahi al-khwarizmi engineering journal, vol. 16, no. 4, p.p. 4151 (2020) 45 fig. 6. upper and lower threshold in ecg signal. then, applying a searching algorithm to find r-peaks that satisfy the threshold of r-peak for 1000 samples of ecg data. according to the index of r-peak, the rest (p, q, s, t) features are obtained such that: q-peak present at 10 points before r-peaks and s-peak at 10 points after r-peak, so the search algorithm applies at the window of index[r-15] to [r] to find qpeak and index[r] to[r+١٥] to find s-peak, hence qrs complex could be found. while ppeak and t-peak present at 100 points of index r-peak, then applying search routine at index[r-100] to [r -25] for finding p-peak occurred before r-peak and for finding t-peak occurred after r-peak applies search algorithm at index of [r+100] to [r+25]. then the intervals of pr, qrs, and qtc are calculated, in addition to a heart rate that calculates from equation [14] hr = fs*60/ rr interval …(6) where hr is the heart rate, fs = 200hz is the sampling rate, and rr is the average rr intervals. thus, if any of these parameters exceed the allowable values (normal value) classified as abnormal conditions by the system as shown in table 1. table 1, normal values of the medical parameters. medical parameters normal value heart rate (hr) 60 – 100 pbm pr intervals 120 – 200 m sec. qrs duration 80 – 100 m sec. qtc 390 – 450 m sec. temperature 36 5 sp67 94 100% 1.1.2 oxygen saturation monitoring: blood oxygen (sp67) is the mean percentage of oxygen (67) that must be carried in the blood, where the normal values are in the range of (94 – 100) [14]. so it is important to measure the amount of 67 in the blood, since the raising or lowering ratio of 67 causes several diseases, for instance, an increase in 67 concentrations causes some cases of poisoning, and this is due to a defect in some vital signs of the lungs. where the sp67 can be measured using the max30100 sensor as shown in fig. , which is attached to the fingertip, and can be wired with the microcontroller via an 879 protocol (sda and scl pins). so when the sensor reading the sp67 value less than 90 or more than 100, the system classifies these reads as abnormal values. fig. 7. sp:7 sensor. qunoot n. alsahi al-khwarizmi engineering journal, vol. 16, no. 4, p.p. 4151 (2020) 46 1.1.3 body temperature measurement: temperature is one of the essential vital signs that aid in defining the health issues of the body vital functions. to measure the temperature there are four ways are axillary, oral, tympanic, and rectal [17,18]. in this work, the max6675 sensor is utilized to measure the temperature see fig.8, which is connected with microcontroller via spi protocol (sck, cs, so). the normal value of the human body temperature is 36 5, so when the sensor reading temperature less than 36 5 or more than 37.5 5, then it will be classified as an abnormal value by the system. fig. 8. temperature sensor. 1.2 processing-unit (esp32) the embedded system that is used in the proposed system relies on a mini-board named the microcontrollers, which includes memory, processing units, and input/ output pin [17]. the microcontroller that is utilized in our work is esp32; it is an open-source environment based on easy to utilize software and hardware [18]. esp32 can be programmed via sending the instructions to the microcontroller to be stored in the memory. the esp32 has two type of communication technologies, which are bluetooth and wi-fi (which has been used in this work) 1.3 alarm-unit this unit is an important and essential issue in the proposed healthcare system due to its usefulness in the alerting process of abnormal conditions. it mainly consists of gsm that is used to alerting physicians in the manner of calling and sms that includes all vital parameters, containing an abnormal value. in this sense, the physician gets alert via call and sms in real-time, anytime, and anywhere. the gsm sim800l model utilized in our system and can be wired with esp32 via the serial port as shown in fig.9. fig. 9. sim800l module. 2) basestation: base-station coordinates the job of each part inside the proposed system. this part represents the intermediate node that connects all parts of the system see fig. 2 .a raspberry pi has been used as the main server, which is responsible for storing patients' node data in the hospital data centres, where it communicates with a patient's node through http protocol. when abnormal conditions occurred, the patient node will send data to the base-station to notify the physician via ringing his mobile, and then he requests the page that view vital signs of the patient from the server. 4. proposed system software design the proposed system software design is represented by algorithm 1 where different sensors data are collected by patient-node which is wears by the patient himself, then process these data by the esp32 unit to check if it is a normal or abnormal data as shown in table1. if any abnormality occurs an alert message would be sent to the physician responsible to that patient. algorithm 1 represents the details for the ecg signal since it considers the most important signal in the system. qunoot n. alsahi al-khwarizmi engineering journal, vol. 16, no. 4, p.p. 4151 (2020) 47 algorithm 1 connected wi-fi read data from different sensors according to sampling rate (for each sensor) while(true) { read 1000 sample of ecg signal; call a routine to analyzed ecg signa;, find ecg features p, qrs, and t periods; compute heart rate; if (all vital signs == normal) status = abnormal; else status = normal; if (status == abnormal) : alert doctor by ringing up his mobile and send sms contain medical data value. establish a connection and upload packet to base-station (server)-show abnormal data in the web page. else: discard the data packet } 5. results and discussion the developed prototype healthcare monitoring system has trends to be an effective and practical medical tool in most of the modes and conditions. this system allows monitoring the electrical activity of the heart and analyzed it. fig. 8, fig.10 (a) shows the raw data signal obtained from healthy personal, while 10 (b) shows the recorded signal after filtering the noise. the system records the window of ecg signal with 5 sec that is sufficient to record more than one pulse, and then check each pulse in this window to make a decision, which enhances the accuracy and response time of the proposed system. in order to give a chance for the physicians to diagnose heart diseases more precisely during real-time remote monitoring. the ecg recorded signal is provided to the physicians is essential to diagnoses in the ecg frame rather than depending only on the heart rate. besides, provides essential vital signs like temperature and spo� see fig.11. where providing this information in anytime-anywhere in the world, so it used the web page to achieve this aim. after collecting data from the patient’s body, the system has been analysed and diagnosed whether they are abnormal conditions as shown in table 2, where it makes a calls the doctor to inform him that there are emergency conditions. this alert is made using gsm technology in order to overcome the problem of internet disconnection. the abnormal data are transferred to the base-station (main server) to be stored using the http protocol (server-client scheme). this analysing process is accomplished locally (patient's node), which reduces the communication time with the server that reduces the power consumed. qunoot n. alsahi al-khwarizmi engineering journal, vol. 16, no. 4, p.p. 4151 (2020) 48 fig. 10. (a) ecg signal before the filtering process. (b) ecg signal after applying filter and feature extraction. fig. 11 web-page of vital arameters. table 2, experimental results of real persons. the proposed system has been used practically in real-time with different patients with different status such elderly people, chronic diseases, infectious, and critical conditions (emergency). table 3. shows different hardware used with their power consumption. status hr normal 60100 bpm sp67 normal 94100% temperature normal 36 c̊ gender age id normal 73 95.60 36.10 mail 25 1 normal 65 97.50 36.03 female 20 2 abnormal 75 93.50 36.40 female 42 3 normal 68 99.00 36.50 mail 46 4 abnormal 86 96.05 38.00 female 55 5 normal 78 98.20 36.50 mail 63 6 qunoot n. alsahi al-khwarizmi engineering journal, vol. 16, no. 4, p.p. 4151 (2020) 49 table 3, power consumption of hardware design [18],[19]. 6. conclusion this work is an improvement of most existing health surveillance systems, where the designed system considers aspects of precision, size, energy consumption, and limited resource in health centres. the system has been designed to transition to smart systems to provide medical services better than the traditional form and to preserve the lives of people. as well as to reduce death rates because of delays in providing medical services or discovering diseases and its access to stages advanced. the system is smart enough to collect the vital signs from the patient's body and analysed to detect the abnormal condition (emergency). hence, it can be deciding to alert physicians and transferring data to the server to enable the physicians to assess the patient's condition. the physicians can access the abnormal conditions via a designed web page for this purpose. 7. references [1] m. m. baig, h. gholamhosseini, and m. j. connolly, “mobile healthcare applications: system design review, critical issues and challenges,” australas. phys. eng. sci. med., vol. 38, no. 1, pp. 23–38, 2015. 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"sim800l hardware design v1.00", shanghai, 2013. ��� ���ت ���� ا���ھ�� ا�%�ارز� ا�"�! �� ا���� 4، ا�'!د16!)*+ ،2020( 4151( 51 ا���. �-�م / �278 63 5'! �'4�! 2�3 ا�01رات ا�(������ ��8ا�:� ا���38� ا�9(� ا�(;�; �3 /�7< ا��8ھ�ن** *���ت ���� ا���ھ ***!�? 6��? �3 >;: 019م ا%07,8ب/ 215* ا%4#23* %1$01م ا%)#.* /-,+$* ا%()#ة /ا%$#اق* ا%<a@7* / -,+$* ا%()#ة /ا%$#اق / 215*>;: ا%<a@7* ا%?<3#,=2* ** / -,+$* m3@اد/ ا%$#اق/ 215* ا%<a@7* ا%0kارز+h>;: ھa@7* ا%f$01+,ت و اc,(dcت *** *hn4#و?%cا @o#)%ا: qunootalsahi@gmail.com ** hn4#و?%cا @o#)%اali.marhoon@uobasrah.edu.iq: *** hn4#و?%cا @o#)%ا: ahamad@kecbu.uobaghdad.edu.iq � ا�%@+ 3,4f%ا>(* وا#f%ت اp?qf%ه اsھ t1u4d ,+ ,ً)%,wو ،t1y%وا z24=#%ا h. 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[7#o ~n�. *2$2)2# طw *28(%ل 05ن ا%8,%* ا,k h. ، c%ذ g%إ *.,nw,3 .,>%0k ار#y%ا qa]ت و,n,2)%ه اsة %21841] ھ@o@ت,n,23 ةs و[m# إsnاًرا %�ط(,ء 9(# رz2n ا%<,d| ا%0f8fل وا%#7,=] ا%a)2* ا%y)2#ة g19 t1m41% اuyn,ع ا2f(d :d j2k .�n#4nw: ا%aa,م �2y84% ا%@>* :p8%ا ، [f$%ا اsھ h. ر,$q47cأ-<}ة ا z+ 0اعnأ *�p� ام@k479(# ا `dkaf%ا *<,u%ك اp>47واecg ،spo2 *-ر در,$q47وأ-<}ة ا ، c,(dp%. esp32ت ، ووk@ة ا%84?: ا%#=h. *2;2 ھsا ا%$f] ھh وk@ة sim800l gsm ا%8#ارة. أd ، ,�ًo: اk47@ام وk@ة this is an open access article under the cc by license : al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 21, no. 4, december, (2025), pp. 106124 object dimension and location determination in gantry robots and conveyor systems: a review hayder ali saadi1, nazar kais al-karkhi2*, wisam t. abbood3, and somer nacy4 1,2,3 department of automated manufacturing engineering, al-khwarizmi college of engineering, university of baghdad, baghdad, iraq 4 department of mechanical engineering, san diego state university, california, united states *corresponding author’s email: nazarkais@kecbu.uobaghdad.edu.iq (received 4 august 2024; revised 11 january 2025; accepted 10 april 2025; published 1 december 2025) https://doi.org/10.22153/kej.2025.04.012 abstract a gantry robot is one of the most common types of industrial robots with linear movement. this type of robot is also known as a cartesian or linear robot. it is an automated industrial system that moves along linear paths, enabling it to create a 3d envelope of the space in which it operates. a robot of this type has a standardised configuration process because it can have several sets of axes, such as x, y and z. the gantry robot picks up products from several places, so it can search through various locations. afterwards, it carefully deposits the products on a conveyor belt for the next stage of the procedure or final shipment. this integration enables continuous and automated material flow, increasing overall productivity and efficiency in manufacturing operations. dimension measuring and object placement are critical tasks in robot and conveyor systems that depend substantially on the types of sensors. progress in sensors and camera technologies has markedly enhanced precision, efficacy, productivity and adaptability. sensors are commonly classified as range and vision sensors on the basis of their mode of measurement. this review article offers useful knowledge on gantry robots and conveyor systems and their historical background. it examines recent research that has reported on the advantages and disadvantages of gantry robots. moreover, literature on object dimensioning and positioning via sensors and cameras in gantry robots is presented. this review elucidates the advantages and disadvantages of several sensing types, including cameras and conventional sensors. comparisons of robotic systems in terms of accuracy, speed, cost, energy efficiency and other aspects are also performed. many studies have been conducted on body detection via vision technology and sensors, but the use of laser sensors has received minimal attention and needs further focus in the future. keywords: gantry robot; dimensions; location; sensors; vision; conveyor system 1. introduction the use of robots in various industrial and commercial applications is increasing as robotic technologies develop [1]. these applications utilise robots to help humans perform tasks, and in some cases, they even replace humans [2]. gantry robots can provide complete control of xyz cartesian space along a plane, allowing them to move at high speeds and perform pick-and-place operations with precision [3]. gantry robots, equipped with gripping devices and conveyor systems, are one of the primary agents in the movement of parts, components and products [4]. such pick-and-place and motion control operations mostly depend on https://doi.org/10.22153/kej.2025.04.012 hayder ali saadi al-khwarizmi engineering journal, vol. 21, no.4, pp. 106124 (2025) 107 these large-scale systems [5]. determining human body dimensions is an indispensable task in numerous technological and industrial areas [6]. the success of these systems depends largely on sensor and camera technologies that help express factualness and effectiveness when imparting dimensions and design locations. some sensors and vision technologies, where lasers, infrared and 3d cameras are involved, have been integrated to achieve the same goal through distance measuring and location pinpointing with high accuracy. through these means, the required dimensions and locations can be monitored exactly, thus realising high process efficiency and outstanding performance in a wide range of industrial and scientific applications [7]. some robotics equipment can determine the shapes and sizes of products for classification and sorting through vision [8]. sensing and identifying the most crucial aspects in automated sorting systems that have emerged in this context and that demand thorough focus have been pointed out as crucial. sensing involves not only the detection but also the classification of objects provided for sorting, which in turn requires advanced techniques in data handling and environment awareness generation [9]. furthermore, grabbing, a stage that means attaining the target disunion with the highest degree of precision and effectiveness, should come first [10]. to make materials sufficiently capable, designers should produce mechanisms and devices that consist of intelligent algorithms and a strong processing unit so that the whole system will be reliable, and the sorting task will proceed with upgraded efficiency [11]. cartesian or gantry robots should work along a rigorously marked route, and changes in object dimension and position detection should be minimal only. in a previous study, the researchers demonstrated a robotic system that could locate with high precision and subsequently pick up moving objects from a conveyor belt. the system employs the you only look once (yolo) algorithm for object identification, principal component analysis (pca) for orientation prediction and template matching techniques for accelerating the motion of objects. an artificial neural network is in charge of the three-degrees-of freedom cartesian manipulator that counterbalances the robot arm to ensure accurate understanding. in real dynamic scenes, the system achieves a success rate of 94.86% for vertically oriented objects and 91.43% for horizontally disposed ones, thereby setting the ground for its application in actual scenes [1]. another landmark is the creation of a versatile, three-fingered robotic hand and a vision system to handle multiple objects in various scenarios. the gripper, equipped with visual serving, can perform real-time target tracking and uses a raspberry pi controller for movement. the design adjusts the grippers for different object shapes and attains 100% success in dynamic, nonvisual environments. such a solution is perfect for intelligent manufacturing because it facilitates calibration, reduces occlusion and increases precision [2]. in the industrial automation domain, a gantry robot has been constructed for pick-and-place operations with the help of a vision control system. using python and opencv, the robot decides whether to put the object in the blue or yellow drawer and then sends the respective control instructions to an arduino mega 2560 microcontroller. devices like this are space and time savers, so they are in line with the principles of industry 4.0 because they aim to streamline operational processes in tightly spaced environments [3]. a robotic work cell has also been developed to perform tasks, such as sole digitisation, glue application and grasping with an amount of variability that is typical of a footwear manufacturing environment. equipped with rgbd cameras and laser scanners, the system determines the grabbing points for shoe soles of different shapes and sizes and achieves 97.5% success. the aforementioned robot methods resolve sophisticated manufacturing problems by minimising manual labour with high production efficiency [4]. another approach is the use of twofinger grippers so that the system can grasp objects as they pass down conveyor belts and rotating platforms. this system provides real-time recognition and dynamic object tracking by applying the you only look at coefficients model from object recognition and long short-term memory (lstm) network and convolutional neural network (cnn) from trajectory prediction, which can be used for vehicles and pedestrians. all system components are integrated using the robot operating system (ros), which is designed for handling objects in dynamic environments [5]. research has also introduced a robotic gripper for industrial assembly tasks integrated with a vision system. the method automatically recognises the part’s positions and determines the best points to grasp that part without previous training. similarly, a robust, three-finger, adaptive gripper with ros has been designed, and it is particularly suitable for high-mix, low-volume manufacturing scenarios where parts may be unstructured or randomly oriented [6]. for coal sorting, a delta-type parallel robot has been established for sorting coal and hayder ali saadi al-khwarizmi engineering journal, vol. 21, no.4, pp. 106124 (2025) 108 gangue on a conveyor belt. the system uses the kemotion control system that combines vision and calibration methods to virtually configure the robot with the conveyor belt. this method increases not only recognition efficiency but also robot sorting accuracy, thereby decreasing manual labour [7]. essentially, this study was the first to present a robotic manipulation system that uses event-based cameras to improve the robot’s dexterity in tasks, such as grasping or drilling. the system is highly sensitive to motion and has very low latency and very high temporal resolution; thus, it can track fastmoving objects in a wide range of lighting conditions, and it does not compete but rather contrasts with conventional cameras. this ability provides the system more precision and more freedom than what is possible in traditional vision systems [8]. by integrating positionand imagebased visual servoing, the authors developed a novel graphical framework that facilitates the design of mechatronic systems and makes the mechanical designs transition smoothly into electronics. motion control, the main tool used by the virtual electronic auditors in this framework, is the means by which electronic data components are extracted; thus, designers can co-operate effectively. the system is compliant with iec 61131-3, and particular libraries contribute not only to the clarity but also to the efficiency of mechatronic designs, especially when systems are complex [9]. many other studies have also identified automating sorting as a key issue to be resolved by optimising pick-and-place operations. one study substantially altered throughput and system sorting accuracy by focusing on gripping efficiency and the implementation of dynamic scheduling algorithms that it can be regarded as a breakthrough. the system adjusts itself to various item flows through the use of simulations, so it can operate efficaciously at low costs [10]. another study created a local automated orderpicking system that addresses many orders simultaneously. the workstation is a blend of conveyor belts, robots and a carousel mechanism, leading to a reduction in processing time and an increase in productivity. different types of picking policies were tested in the study, and a notable increase in throughput and decrease in system bottlenecks were achieved [11]. a gantry robot was built in another work to perform pick-and-place operations in material handling, and the robot was further upgraded with an obstacle detection capability. the robot is controlled by a programmable logic controller (plc), and a vacuum cup is used to pick up objects gently. this automation leads to increased operational efficiency and reduced human labour and ensures safety in cases of obstacle interference during material transfer [12]. in another study, an automated storage and retrieval system (as/rs) was created in the form of a gantry robotic cell with a conveyor belt and light sensors. storage and retrieval operations are performed automatically by plc. through this integration, storage efficiency is improved, sorting and retrieval speeds increase, and human intervention is substantially decreased [13]. meanwhile, another study designed a system for predictive maintenance of gantry cable-track systems to locate faults in critical industrial processes. the system relies on gyroscopes and accelerometer sensors to collect data for failure prediction and safety enhancement. the patterns from the diagnostic data of pumps were revealed, enabling the extraction of signatures and early warning methodologies, which were used for fault location through the two-group t-test in statistical analysis to determine the causes for cutting down maintenance costs and downtime [14]. in another work, a robotic arm for sorting, placing and counting was built. this system is coupled with a conveyor belt. when ir sensors detect an object on the conveyor, the system turns on an arm for precise material handling. such a system reduces human intervention and raises the level of efficiency and accuracy in repetitive tasks; these capabilities are crucial for food processing and packaging and other industries [15]. moreover, a gantry robot that can autonomously play checkers by using neural networks and computer vision has been introduced. the system employs reinforcement learning to make moves by combining the test board and pieces with a camera, and the camera feed is processed through opencv. although the system faces substantial challenges in terms of lighting, it can play the game accurately and smoothly [16]. meanwhile, a benchmarking study has reported that q-learning is more effective than state–action–reward–state–action (sarsa) for robotic pick-and-place tasks in non-visual environments. q-learning, after being trained in several shapes, object dynamics and belt dynamics, can achieve more than 90% success, whereas sarsa has a lower success rate, especially for spherical objects and at high speeds [17]. the study examined the deployment of gantry robots and conveyor belt systems, with focus on the integration of vision and sensing technologies to elevate dimensional accuracy and operational efficiency. it conducted a detailed investigation of the advantages and disadvantages of gantry robots and highlighted the challenges in sensing, grasping and manipulation in these systems. cartesian or gantry hayder ali saadi al-khwarizmi engineering journal, vol. 21, no.4, pp. 106124 (2025) 109 robots should move along a precisely defined path, with minimal changes in object dimensions and positional sensing. sensors and camera vision can help determine body dimensions and position. this review discusses the gantry robot and conveyor system, including its working principle, advantages, disadvantages and types of sensors used and their working principle. the determination of body dimensions and position by range and vision sensors is discussed in detail. 2. gantry robots and conveyor belts the gantry robot was first used in 1977 by r. a. jarvis [18]. gantry robots can make use of almost all their space and size, filling up to 96% of their cubic work envelope [3]. a cartesian robot has three axes for operation. x, y and z typically denote coordinates in three dimensions (figure 1). the arrangement of each axis is perpendicular, enabling three degrees of mobility [19]. unlike robots with arm configurations, gantries can easily expand to large dimensions in all three axes. gantry robots are particularly suitable for situations with few additional orientation constraints or where the robot can arrange the pieces in advance before picking them up [3]. cartesian and gantry robots have a rectangular or cubic work envelope, unlike articulated robots, which, similar to the joints in a human arm, have defined boundaries for each movement and a predefined range of motion. consequently, the degree of movement is represented by wide, sweeping arcs, which are the main depiction factors. these arcs illustrate positive and negative degrees of movement as they rotate around the centre of the base and the bearing of each axis. notably, these non-standard work areas often entail changes to the workspace, instead of the robot modifying the environment [20]. cartesian/gantry robots have an extremely high level of accuracy and repeat ability as a result of their rigid yet lightweight structure. gantry robots are easy to program and deploy when assessing new automation because of their straightforward structures. most gantry robots are customisable. equipped with a wide range of motor and gearbox options as well as various components and materials, these robots are ready to address the difficulties posed by damp, dangerous, unclean environments [21]. the cartesian coordinate robot’s simplistic form and uncomplicated operation make it highly favoured in the industrial industry. by allowing for easy replacement of individual axes, the system minimises downtime and keeps maintenance costs low. furthermore, the entire system can be dismantled into its constituent elements for use in other single-axis applications. moreover, cartesian coordinate robot systems are more cost effective than intricate robots [22]. the use of the conveyor belt began in 1909 [23]. in may 2024, lim jun designed and developed a conveyor belt system. this system, which moves materials and items from one location to another with high accuracy and speed, plays a crucial role in manufacturing and production facilities. the conveyor belt is essential for continuous, stable operation because it ensures that the production line and storage distribution centre function smoothly. the conveyor belt structure consists of mechanical and electronic components that work together to optimise usage while allowing production to be achieved without errors or downtime [24]. an automated conveyor belt relies on advanced electronic systems, which are composed of microcontrollers and sensors that interact with the environment as needed. polyvinyl chloride is used to make this conveyor belt, which is known to be durable and highly resistant to heavy loads and wear. given that it allows for easy and secure transportation of products, this system is ideal for various industries, especially in the food industry where the conveyor belt is made from either thermoplastic elastomers or stainless steel, adding to its resistance to corrosion [25]. wear and corrosion-resistant metal rollers are the belt’s supporting elements, and they guide it during operation with damping vibration. the conveyor is powered by different kinds of electric motors, such as ac motors that deliver continuous power for heavy-duty applications, dc motors that provide variable speed for precise speed control and servo motors that automatically adjust conditions with dynamic response to high-level control in complex operations. notably, many other high-end technologies (e.g. plc control for the conveyor, where plc manages the belt speed and direction depending on the data received from sensors and cameras) are available [26]. sensors provide exact information about product weights and locations, and cameras, being a part of the machine vision system, detect quality issues, such as damage or misclassification. these combined systems make up an ideal approach to minimise waste and maximise production efficiency. they have robust engineering and integrated technology to implement quality and safety solutions for products during transit [27]. the carriage is aligned with the gripper at the specified corner on the basis of the plc signal, and the conveyor belt stays immobile, awaiting the item. the gripper seizes the object and deposits it on the conveyor belt at the specified home position. a hayder ali saadi al-khwarizmi engineering journal, vol. 21, no.4, pp. 106124 (2025) 110 signal is then sent from plc to commence the conveyor’s operation for the item specified for retrieval [28]. shubha and rudresh concentrated on a project involving a colour sensor-based objectsorting robot, with the primary purpose of developing an automated material handling system. the item on the conveyor belt is retrieved when the microcontroller instructs the robotic arm by synchronising its movement. all items are organised by positioning them in their designated locations after being retrieved from the conveyor. accuracy and repeatability in tasks are attained when human labour is performed by robots [29]. fig. 1. gantry robot [3] 3. advantages and disadvantages of gantry robots 3.1. gantry robot advantages [30, 31, 3] 1. the robot is capable of extremely fast and accurate item repositioning, which is an absolute necessity in such industries as medical device assembly and semiconductor manufacturing to guarantee excellent results [30]. 2. gantry robot systems can be used in logistics and manufacturing. they can carry different weights and sizes of items, making them perfect for 3d printing, milling and pick-and-place systems [31]. 3. cartesian robots always have the same shape even when the tool is in a different location. gantry systems are modular, so they can be easily scaled up or down for large or small objects depending on the project needs [31]. 4. compared with other robotic systems, such as articulated arms, gantry robots can take advantage of their vertical and horizontal dimensions much more effectively, hence reducing the distance to the components, decreasing the amount of guide way material and ultimately conserving floor space [3]. 3.2. gantry robot disadvantages [32, 33] 1. gantry robots need a large area for installation because of their sizable frame and long travel range [32]. 2. the installation of gantry robots is usually a complicated and lengthy procedure, and it may require specialised knowledge and equipment [33]. 3. the cost of a gantry robotic system is a considerable one at the outset; this cost is inclusive of the expenses of the robot, the installation and any necessary changes to the facility [33]. 4. gantry robots might not be suitable for tasks that are complicated and require multi-directional movements or operations in a confined space [33]. 5. given their large size and lengthy axes, gantry robots can have vibration and resonance problems, especially when operating at high speeds [33]. 4. determination of body dimensions and position by range sensors a gantry robot has sensors to determine the measurements of the body and the subject. the precision and effectiveness of a sensor in locating and measuring the body depend on the degree of its interaction with various production and processing programs in the robot. combining sensor aids can improve the accuracy of the position and speed of determining the objects [34]. in a previous work, a method involving merged visual and proximity sensing of a reticular structure was established to capture objects [12]. the technique ensures that both sensors provide overlapping cover for the region in question. the sequence of motion employs a control base to predict the trajectory of the object as it goes to the desired position, correct approach errors and grab the object firmly [35]. another study integrated vision and proximity sensors into the robot to enhance its capability. the vision sensor helps locate the route by checking a large area [24], and the proximity sensor, which is in the hand’s mesh structure, eliminates the errors of the approach; only then can the hand grasp the object. the integration instigates the hand’s skill of environmental perception [36]. various control loops can be used for coordinating the gantry robot’s actions with those of the conveyor system [16] operating at a regular speed. as a result, the system can calculate an object’s position with high accuracy and retrieve it [13]. moreover, the body can be located and measured in numerous ways [37] a result of rapid technological developments and hayder ali saadi al-khwarizmi engineering journal, vol. 21, no.4, pp. 106124 (2025) 111 brilliant inventions [38], especially with regard to storage and retrieval operations. a sensor is an input device, and it is part of a cohesive system. the sensor of this system sends a signal to the main control unit. the sensor receives an analogue signal (e.g. temperature, humidity, colours and light) that is continuous and obtained from the surrounding environment [39]. advanced industrial robotic systems have upgraded the extent to which we are able to determine the dimensions and positions of objects via integrated advanced sensors, algorithms and dynamic control systems. the sensor changes the input into a digital electrical signal that can be understood by the main controller, which issues suitable system commands. for example, peng wang et al. invented a mechanism that locates and measures the positions of objects on conveyor belts in motion by using optical sensors. the information was translated into real-world units through mathematical modelling, and a particle swarm optimisation (pso)-based control system was used to adjust robot trajectories; minimal position and speed errors were obtained, showing the system’s capability for dynamic target operations [40]. similarly, hanson et al. presented the prospect system that merges spatial and spectral data by using azure kinect time-of-flight cameras and visible and near-infrared (vnir) spectrometers, resulting in precise material quality evaluation and non-destructive defect detection and paving the way for new industrial applications in material analysis [41]. kiyokawa et al. employed rgb-d cameras, nir spectral sensors and motion planning algorithms, such as moveit, to direct robotic arms in the industrial waste mixture sorting process; this approach reduces manual labour, improves sorting accuracy and increases material adaptability capabilities [42]. soetedjo et al. enhanced sorting functionalities by creating a system that employs zx distance and gesture sensors and tcs3200 colour sensors to study the object location, dimensions and colour on conveyor belts, thus confirming the sorting accuracy in assembly lines and material verification [43]. ljutjuk et al. developed an as/rs powered by rfid sensors for accurate item tracking. the system, powered by flexsim software, employs mechanical agents, such as forks and suction cups, to enhance operational efficiency, reduce errors and meet high-performance standards [44]. ku et al. were the first to build a cartesian robotic system for sorting construction and demolition waste. they used laser sensors to create 3d images of objects and advanced algorithms (e.g. newton–raphson) to determine the ideal grasping points. with an output of 2,000 items per hour and a success rate exceeding 90%, this system demonstrates a high level of efficiency in managing various materials [45]. bargiotas et al. created a gantry robotic system for as/rs that employs laser sensors for the identification of objects and plcs for accurate guidance of the robotic arm. this system optimises storage and retrieval operations, decreases costs and increases accuracy [13]. carlsson et al. created a robotic claw mechanism that leverages infrared and ultrasonic sensors to follow and grab fast-moving objects in real time. the arduino uno-controlled system demonstrated the success of the infrared sensor in dealing with a fast-moving object, therefore providing a few ideas for potential enhancements of sensor integration and algorithms [46]. meanwhile, akrawi developed a masonry robot system equipped with ultrasonic and laser sensors for precise alignment of building blocks in a construction site. the system, which is pilot-guided by a rule-based expert system, allows accuracy even in unpredictable environments; thus, it reduces mistakes and increases productivity [47]. these studies have revealed substantial advancements achieved in the integration of sophisticated sensors, optimisation algorithms and dynamic control systems for the improvement of the determination of the dimensions and positions of objects in applications in different industries. internal and external sensors are frequently utilised sensor types. robots employ external sensors to gather data, including the specific location where the robot comes into contact with the product it is manipulating, from the surrounding environment. distance sensors are commonly classified in accordance with their mode of measurement [48]. the following section presents commonly acknowledged sensor categories. 4.1. ultrasonic sensors ultrasonic sensors were frequently utilised in the past, but advancements and cost reductions in alternative sensing technologies have reduced their frequency of use. an ultrasonic sensor is a device that can measure distance and object speed without making physical contact. it operates by utilising sound waves at a frequency higher than the range of human hearing (figure 2) [49]. hayder ali saadi al-khwarizmi engineering journal, vol. 21, no.4, pp. 106124 (2025) 112 fig. 2. working principle of ultrasonic sensors [49] the following drawbacks diminish the competitiveness of ultrasonic sensors. • sound experiences deflection when it strikes inclined surfaces, resulting in measurement mistakes. • the proximity of the sensors causes interference. • the precision of the measurements depends on the amount of intricacy. • sample collection is relatively slow. the main advantages of this sensor are its low price and ability to withstand fog and dust. the hcsr04 ultrasonic ranging module features a noncontact measurement capability and can measure distances from 2 cm to 400 cm. it has a ranging accuracy of up to 3 mm. the modules consist of ultrasonic transmitters, receivers and control circuits. the fundamental work premise is as follows: 1. an io trigger is used to generate a high-level signal with a duration of at least 10 μs. 2. the module independently emits eight 40 khz pulses and identifies the existence of a corresponding pulse signal. if the signal returns at a high level, the duration of the high-output io represents the time it takes for the ultrasonic signal to be sent and returned. the formula to calculate the distance is as follows: d = (t × v) / 2, (1) where d is distance (mm), t is time (s) and v is the velocity of sound (340 m/s). 4.2. infrared sensors (e18-d80nk) an infrared sensor typically finds the distance to an item by sending out infrared light signals and determining the reflection angle by triangulation. when an infrared light-emitting diode (led) sends a beam of light to an object, the light is reflected in various directions. the proximity sensor, which is located near the infrared emitter, sees a light wave that has been reflected. the proximity sensor determines the distance to the object by using the angle at which the signal was sent [50]. the working process of an infrared sensor is explained in figure 3 [51]. fig. 3. triangulation procedure of the infrared sensor [51]. infrared leds emit a very narrow beam of light to a particular area of a nearby object. the object reflects the optical signal; thus, the signal reaches the proximity sensor at an angle. the proximity sensor uses this information to perform a mathematical calculation of the distance. the e18d80nk digital infrared sensor is equipped with a distance detection feature. a potentiometer with a range of 3–80 cm can be used to determine the measurement. an infrared transmitter emits infrared light in each sensor, and an infrared receiver detects the reflected infrared light from the object. this sensing enables the sensor to confirm if the object is within a specified range. the diagram of the implemented infrared sensor is e18-d80nk. interference has an extremely low chance of disturbing visible light. therefore, the external influences have a very minimal effect on the error margin [52]. 4.3. light detection and ranging sensors light detection and ranging (lidar) sensors use ultrasonic and infrared sensors as their basic tools. the light component of lidar sends a laser beam towards the target to determine the distance. then, the target area gives off a light signal that bounces off and is picked up by the lidar device. the amount of time the laser signal took to travel is multiplied by the speed of light in the air to locate the place of the object, as shown in figure 4. this method allows tiny objects to be pinpointed at the most accurate level of precision that is of the highest order (e.g. 0.005% of the final range). however, hayder ali saadi al-khwarizmi engineering journal, vol. 21, no.4, pp. 106124 (2025) 113 these sensors are costly in a few instances, and some of them may be dangerous to human eyes [53, 54]. fig. 4. measurement principle of lidar sensors [54]. 4.4. laser sensors laser sensors are mainly used to measure physical characteristics, such as distance, velocity and vibration. typical laser instruments include laser range finders, laser displacement sensors, laser scanners and laser trackers. the core of laser range measurement involves three basic concepts: time of flight (tof), triangulation and optical interference. tof refers to the time interval from when the laser is sent to when the reflected light is received [50]. the laser range finder is a tool that measures long distances [51]. the tof method is predominantly employed when long distances are to be measured. these instruments are specially designed to sense their targets. the setup utilises a transmitter diode to generate short bursts of infrared light that hit the surface. the object reflects light, which is then detected by a receiver diode through transmission and reception. the brightness levels are compared, and the sensor’s distance from the object is calculated [52]. measurement accuracy in tof is limited by the precision of the measurement, which is in turn restricted by the high speed of light. the laser distance sensor uses a very narrow beam of light to determine the exact distance to a certain item. recognition and detection of 3d objects, regardless of their nature, colour and brightness, are also performed. the triangulation method applies the concepts of homothetic triangles and trigonometric functions to conduct measurement calculations and locate elements relative to each other. the laser displacement sensor implements this method to achieve measurements at short distances [55]. optical interference is the result of the overlap of two light beams of different wavelengths, leading to the formation of an interference pattern. the phase makes the stripes bright and shadowed. displacement measurement by the laser tracker is one of the applications of this technology. the distance to the target is determined by using a sensor equipped with a reflector. laser sensors can perform non-contact distance measurements (figure 5), and they are very fast and accurate. however, variations in temperature and atmospheric pressure could influence the wavelength of a laser. changes in atmospheric humidity and moisture content may require modifications to be made [53]. fig. 5. time-of-flight measurement principle [54]. 5. determination of body dimensions and position by vision sensors a purely event-based visual service method can be employed to solve automated processing tasks; for example, an event camera can be used in eye– hand configuration, and multiple perception algorithms with vision-based robotic controllers can be adopted to manage the robot’s movement during processing tasks [56]. the vision system undertakes the acquisition and analysis of field images to detect objects then sends the coordinates of these objects to the gantry robot. industrial processes have placed increasing demands on automation, resulting in substantial advances in robotic vision (e.g. object identification, tracking and manipulation). for example, a stationary camera system using hikvision industrial cameras is employed to view a conveyor belt, and a mobile camera is mounted on the arm of a robot helps pick items and assemble them. using halcon software, the system performs image processing tasks, such as calibration, edge detection and template matching, reporting the object’s size, position and orientation even when data are incomplete. this method had a success rate of over 98% and substantially reduces production cost and manual labour [57]. in other instances, a dual-robot arm is used with an rgb camera to classify and sort objects by their hayder ali saadi al-khwarizmi engineering journal, vol. 21, no.4, pp. 106124 (2025) 114 shape and size. the optics and technologies system adopts image processing techniques, such as greyscale conversion, noise filtering and contour extraction, to detect objects and compute their centroid. the calculated 3d coordinates can be used by the robot to efficiently handle and classify items on production lines [58]. for complex object grasping, a neural network method, such as asp unet, takes in rgb images, which are converted into greyscale maps to identify possible succour points. then, the dimensions of an object and its position distance are calculated from one point to another point. this approach is memory-light and usable on low-cost devices, such as nvidia jetson nano [59]. for example, in waste-sorting applications, a robot autonomously learns how to efficiently pick items. a heightmap of the conveyor belt to find object positions is created using a 3d camera. this process involves an initial geometric algorithm that identifies candidate gripping points, followed by refinement through a machine learning model that learns which of the points succeed through gripping feedback. the system can clear the conveyor belt by scanning and picking most of the objects over time. the performance of this iteration is improved, allowing the system to learn and adapt efficiently [60]. moreover, a trajectory planning method is used to coordinate robot activities with dynamic targets to follow and understand fast-moving objects. the robot used in industrial vision systems and real-time sensors can calculate the motion from the object and estimate an optimal trajectory. a sevenstage planning model considers limitations (i.e. acceleration and speed), and pso minimises the execution time and achieves high tracking accuracy [40]. meanwhile, an approach in the context of robotic welding employs a three-degrees-offreedom manipulator paired with a camera for process detection and tracking of seams. algorithms, such as canny edge detection and tophat transform, are used to process images, helping identify the welding line to show the path for the robot to follow. an adaptive neuro-fuzzy inference system is incorporated for precise kinematics, which enhances welding performance and reduces errors [61]. a lightweight cnn in a yolov3-tinybased model has also been used in object detection for real-time object segmentation in manufacturing. a pixel-level feature analysis for detecting object boundaries is achieved using the intensitydifference search (ids) algorithm for segmentation improvement. this system is utilised to calculate the dimensions and orientation of an object correctly, and grasping is performed accordingly; it is suitable for smart factories [62]. the latest technology that is being used in thermal forming for ship fabrication is a laser scanning system that detects the boundaries and surfaces of curved plates and thus generates precise data for heating instructions. by using this information, the system controls a high-frequency induction heater mounted on a robotic arm to conduct the procedure, resulting in an efficient, automated process [63]. then, an object classification system on moving conveyor belts identifies and processes images to sort objects. the images are processed, and unwanted areas of images are discarded. running algorithms, such as canny edge detection and pca-sift, are employed to distinguish objects in images on the basis of colour, contour, or shape. the use of this system in dynamic industrial settings satisfies real-time performance constraints by enabling fast sorting and picking [64]. different types of cameras are adopted in different situations to determine the physical dimensions and position of the body in the case of robots. conventional rgb cameras take detailed images, which can be further processed to extract depth and dimensions with the help of a machine learning algorithm (figure 6) [65]. fig. 6. diagram of object capture by an rgb-d camera [65]. as shown in figure 7, stereo vision cameras typically comprise two or more cameras situated at different angles and are frequently employed to obtain depth information via disparity analysis. tof cameras are mainly preferred because of their effectiveness. they send out modulated light signals and determine the time needed for the light to return, thereby generating accurate 3d maps of the scene. structured light scanners project patterns on objects and analyse the deformation of these patterns to reconstruct 3d shapes accurately [66]. hayder ali saadi al-khwarizmi engineering journal, vol. 21, no.4, pp. 106124 (2025) 115 fig. 7. time-of-flight camera principle [66]. furthermore, rgb-d cameras that merge rgb imaging with depth sensors, such as microsoft’s kinect or intel’s real sense, offer total colour and depth data that are very helpful for accurate positioning and measurement. lidar devices, which are known for aiding in navigation and detecting obstacles, can also be used to produce detailed 3d models of a robot’s surroundings. these camera technologies allow robots to obtain exact measurements and positioning, thus increasing their working capabilities and ability to adapt to the everchanging environment. to solve the aforementioned problem, researchers have developed a vision-based control system that makes the system dynamic in nature. a usb camera is used to take images, and these images are handled by open-source software, such as opencv, in computer vision. the microcontroller converts the particular object in the photo by accurately recognising the colours and features [27]. 5.1. advantages and limitations of rgb-d cameras [65, 66, 67] 5.1.1. advantages of rgb-d cameras [65, 66, 67] the advantages of rgb-d cameras are as follows: 1. adequate energy performance [65], 2. high frame rate and long battery life [65], 3. passive high resolution [66], 4. generates a 3d representation of an object or scene with coloured data points [66], 5. classification of accuracy among objects that are comparable [67]. 5.1.2. limitations of rgb-d cameras [65, 66, 67] the limitations of rgb-d cameras are as follows: 1. robust non-textured regions [65]; 2. low-precision distance measurement, thermal stability, and repeatability [66]; 3. lack of features in scenes [67]; 4. no correspondence in different views of the camera [65]. a summary of the methods used for object identification, dimension measurement and position determination via range and vision sensors in robotic conveyor belt systems is given in table 1. table 1. summary of the methods used for object identification, dimension measurement and position determination in robotic systems the object is identified dimensions are measured the position is determined peng wang et al. [40] optical sensors identify objects located on moving conveyor belts. mathematic mathematic modelling converts sensor data into realworld measurements. based on sensor data, this approach uses particle swarm optimization to optimize robot trajectories. nathaniel hanson et al. [41] spatial and spectral data are collected via azure kinect time-of-flight cameras and vnir spectrometers. spectral data provides material analysis, contributing to dimension estimation. the 4d model combines spatial and spectral information for position characterization. takuya kiyokawa [42] rgb-d cameras, nir spectral sensors, and motion planning algorithms index objects. dimensions are estimated based on the assessment of camera data and sensor readings. the robotic arm is guided by the moveit algorithm, which takes the position and dimensions of the object into account. aryuanto soetedjo [43] zx distance and gesture sensors, tcs3200 color sensors, filtering objects on conveyor belts. zx and color sensors measure the geometric location, dimensions, and color of objects. the position comes from some processing of sensor data by an arduino mega2560 controller. hayder ali saadi al-khwarizmi engineering journal, vol. 21, no.4, pp. 106124 (2025) 116 conrad ljutjuk [44] rfid sensors monitor the location of items in cases like asrs (automated storage and retrieval system). physical instruments (e.g., pressure gauges and vacuum devices) measure dimensions of objects. rfid incorporated into flexsim inform object positions. yue-dong ku [45] laser sensors create 3d images of objects for sorting and identification. object dimensions are computed using 3d pictures produced by laser sensors. robust algorithms (e.g., newtonraphson) improve the focal point and position. ata a. [13] this uses laser sensors to classify objects by adding laser beam interruption. object classification via laser sensors helps measure the dimensions of the objects. robotic with position-based plcbased control can store and retrieve items. matthias carlsson [46] infra-red and ultrasonic sensors detect movement that can be identified. infrared and ultrasonic sensors detect the shape and distance of fast-moving objects. the sensors perform position tracking in real-time, while gripping is done using algorithms. shereen ghanim akrawi [47] block identification: ultrasonic / laser sensors for construction environments the sensors take real-time measurements of the blocks' dimensions. it uses rule-based expert systems to process sensor information and define the treatment process precisely. cong, v. d.et al. [57] uses hikvision industrial cameras for visual identification uses halcon software, minimum rectangle fitting for dimensions uses image processing, template matching, and edge detection for location determination dolezel, p.et al. [58] image processing (grayscale, noise filtering, contour extraction, classification based on area, perimeter, and compactness) rea (using image moments), perimeter, and compactness c=p2ac = \frac{p^2}{a} are calculated to identify the shape and size. centroid (cx, cy)(c_x, c_y) is calculated using image moments. it is converted to 3d coordinates relative to the camera’s frame. stogl, d.et al. [59] asp u-net detects grasping points and highlights them with geometric gradient shapes. the distance between grasping points is used to estimate the size of the object. 2d pixel coordinates (x, y) of grasping points are passed to the robot arm. no 3d information is used. peters a et al. [60] uses a 3d camera to create a heightmap of the conveyor. geometric algorithms propose initial gripping points. machine learning refines the best picking point. extracts object dimensions from the heightmap data provided by the 3d camera. computes the object's location relative to the conveyor using the 3d heightmap and calibrated coordinates of the robot's gripper. wang, p et al. [40] employs industrial vision or sensors to locate moving objects. tracks real-time position using conveyor speed and direction data. computes object dimensions from optical or sensing inputs integrated into the mathematical trajectory planning model. determines the location based on real-time tracking of object motion using vision or sensors integrated with trajectory planning. hayder ali saadi al-khwarizmi engineering journal, vol. 21, no.4, pp. 106124 (2025) 117 al-karkhi, n. k.et al. [61] utilizes a camera to capture images of the workpiece. image processing algorithms detect edges and weld seams (e.g., canny edge detection, top-hat transform). measures dimensions by converting image coordinates to real-world dimensions using intrinsic and extrinsic camera calibration. uses edge detection and weld seam identification in image processing to locate the target line relative to the camera's calibrated plane. cho, j.et al. [62] uses yolov3-tiny for real-time detection the ids algorithm extracts precise object boundaries geometric analysis calculates position, orientation, and grasping points park, j.et al. [63] pre-scanning with multilvs detects plate location in the work area detailed measurement using local-lvs, approximations via nurbs curves position and curvature derived from 3d surface approximations tran, h.n.et al. [64] analysis of images captured by a camera, using thresholds for color detection and edge contour analysis simplifies object shapes into polygons based on edges calculates the center of mass and angle from polygon vertices 6. system performance criteria modern-age robotic systems are crucial for enhancing the efficiency and performance correctness of different industrial tasks. however, these systems entail trade-offs in terms of reliability, throughput, price and power draw, so the choice of which is ideal for a given application tends to be highly application specific [68]. a comparison of several robotic systems in terms of important parameters, such as accuracy, speed, cost and energy efficiency, is provided as follows: 1with regard to systems used for precision applications, such as micro-assembly, chengyen chen [20] studied ways to improve positioning accuracy in bridge systems. laser doppler displacement measurement techniques were used to identify spatial errors, and compensation logic on the basis of a b-spline command generator was developed. the outcome was 50% more accurate than the standard outcome of ±3 µm. given the use of advanced technologies, this approach has a high initial cost but offers high energy efficiency with permanent magnet motors. 2sharath et al. [3] highlighted that the arduinobased gantry robot achieves an accuracy of only 85%–90%; it is limited by the precision of the stepper motors and the computational capacity of the arduino mega 2560 microcontroller. its velocity is moderate, which is suitable for minor tasks. this system is economical because of the use of readily accessible components and simple hardware. energy consumption is negligible because of the use of lightweight materials and low-power components. 3vall et al. [19] worked on a bridge robot design that uses linear motors and inductive sensors, resulting in high precision and safety. the design is responsive to the requirements of tasks with a high applied speed, with its maximum speed of 6,000 mm/s. the system is expensive to install, but because of its energy conservation and low maintenance, it could provide cost savings after some time. 4 thatere et al. [12] presented a controlled scenario where human-like accuracy is obtained through proximity sensors; however, the exact numbers were not given. the presented system has slow motion and uses 200 rpm dc motors, which are typically utilised in elementary pick-and-place operations. by employing common components and consuming the least energy possible (the system depends on low-power motors and pneumatic systems), the technology is economically efficient. 5freeman et al. [26] demonstrated that by using iterative learning control (ilc) to reduce errors in task repetition, the system can achieve an accuracy of over 99%. the speed is extremely high due to the optimisation of the motion trajectories. however, the costs are high because of the difficulties in implementing ilc, but the energy consumption is efficient because unnecessary movements were minimised. 6kujala et al. [27] presented a system that is only 87.5% accurate at first; then it improves through hayder ali saadi al-khwarizmi engineering journal, vol. 21, no.4, pp. 106124 (2025) 118 machine learning. this unit performs very fast work, changing or selecting in under 1.8 seconds. although it is flexible, its costs and energy consumption are high because it depends on advanced computer resources and continuous learning processes. 7shang and wang [7] explored a mechanism that leads to an increase of 72.3% in calibration accuracy. the system works at an average speed because it can process seven images in a second. the costs are low because minimal maintenance is required as a result of accurate calibration, and the power consumption is moderate because the system is optimised through the elimination of unnecessary movements. 8wang et al. [40] reported that the method in question achieves a phenomenal 99.8% accuracy in the localisation and sorting of objects. the speed is moderate, and the variation is 7.4 mm/s. the expenditure is also minimal because of reduced wear and tear resulting from improved trajectory planning. the energy consumption is made efficient by the removal of unnecessary movements. the ilc gantry robot is an example of a device that can be used in situations that require a combination of high precision and high speed. it is known for its accuracy of more than 99% and quick performance, so it is suitable for clean rooms that require continuous high throughput and precision even though it has a drawback of high cost and high energy consumption. for economic efficiency and reasonable precision, the arduino-based gantry robot offers an economical solution with an accuracy of 85%– 90%, making it suitable for small-scale operations, educational applications, or prototypes where budget limitations are critical. the ilc gantry robot is the ideal choice for scenarios requiring precision and speed, especially in high-volume, repetitive tasks. for pick-and-place operations in applications with constrained resources or less rigorous standards, a gantry robot that uses the arduino mega 2560 microcontroller and is processed with python is suitable. table 1 shows comparisons of robotic systems in terms of important parameters, namely, accuracy, speed, cost and energy efficiency. table 2. comparison of robotic systems on the basis of performance criteria sensor type accuracy speed cost energy consumption cheng-yen chen [20]. laser doppler shift measurements high high high low sharath gs, hiremath n [3]. vision (usb camera) 85-90 moderate low very low judith doral vallet al. [19] inductive sensors high (unspecified) high high energy efficient and low maintenance shubhi thatere et al [12]. proximity sensors middle middle low moderate moderate freeman et al. [26]. sensor position (optical encoders) above 99% very high high very efficient janne v. kujala et al. [27]. vision(asus xtion) 87.5 improving fast (<1.8 sec) high high deyong shang et al. [7]. vision(industrial camera) 72.3% improve middle middle middle peng wang et al. [40]. vision(visual servoing system) 90 moderate moderate moderate 7. conclusion gantry robots integrate conveyor systems into advanced automated manufacturing settings to form efficient and seamless production lines. this review examines previous studies on gantry robots with conveyor systems and discusses unresolved issues. by reviewing previous studies, we conclude that robots’ use of sensors, vision systems and cameras provides important advantages that help improve the performance of robots and expand their hayder ali saadi al-khwarizmi engineering journal, vol. 21, no.4, pp. 106124 (2025) 119 capabilities in various fields. these advantages are summarised as follows: 1. vision-based systems (including high-speed cameras and lidar sensors) can achieve high accuracy in dimension detection; such methods are suitable for tasks that require accurate measurements in dynamic environments. 2. sensor-based systems employ ultrasonic and infrared sensors and can achieve approximately 85%–90% dimensional accuracy, making them ideal for low-complexity tasks or applications. 3. structured robotic systems, including cartesian or gantry robots, exhibit highly accurate movements, and their easy sensor integration contributes to accurate dimension detection. 4. the most relevant software use case that can be employed to achieve high accuracy in dimension detection adopts shelf and high-accuracy robotic stacking algorithms, such as ilc, to refine the system and correct errors during repeated task execution. 5. data-driven precision refers to the ability of machine learning algorithms, such as cnns and lstm networks, to attain increasingly accurate results as they learn from new data consistently, allowing them to enhance system performance with time. 6. optical and proximity sensors are integrated to cover various dimensions, leading to increased measurement accuracy in dynamic work settings. 7. integrated systems, such as ros and plc, play a role in coordinating hardware components and provide real-time feedback that can improve accuracy and avoid errors during the dimension detection of systems used in the industry. 8. sensors are less affected by lighting conditions and external environments compared with cameras, making them suitable for harsh industrial conditions. they perform well under various environmental factors, including low light, heat and humidity, and ensure reliable dimension detection in challenging settings. 9. the best plan is a matter of necessity. in the case of maximum accuracy and speed, the ilc gantry robot is the leading tool because it has excellent accuracy and high speed. garbage-sorting systems regard flexibility and multi-tasking as the main features of dynamic environments, as underlined by ai capabilities. in the case of cost cutting, a gantry robot for unpacking and positioning is a good choice for complex applications, such as feeding and final decision handling. accuracy, cost and flexibility should be at the same level as the unique requirements of the project. establishing the distance and location of an object helps. by using a set of sensors, the machine can handle different types of work, thus expanding its flexibility and versatility. 10. the vision and camera technologies used by robots allow them to recognise different kinds of objects and locations by shapes even faster than a human can; thus, they are more efficient in performing tasks. with high-resolution images and videos, they can work exceptionally well in pattern recognition, inventory management and location tracking. the technology also perfectly blends with ai and machine learning, revealing its remarkable potential for system-level integration and dynamic features. 11. the right choice depends on the project requirements, whether it be accuracy, speed, cost, or energy efficiency. systems that utilise optical encoders deliver a very high accuracy of over 99% and high speed, making them ideal for precision industrial applications. the high price of these systems may, however, discourage some projects. meanwhile, a system that employs usb cameras provides a compromise between performance and cost, resulting in an accuracy of about 85%–90% at a low cost and low energy consumption. this system is suitable for nonprecision applications. references [1] k. uçar and h. e. koçer, "determination of angular status and dimensional properties of objects for grasping with robot arm," ieee lat. amer. trans., vol. 21, no. 2, pp. 335–343, feb. 2023, doi: 10.1109/tla.2023.10015227. 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( 2025) 106-124، صفحة 4، العدد21مجلة الخوارزمي الهندسية المجلد حيدر علي سعدي 123 ايجاد بعد وموقع الجسم في نظام روبوت القنطرة والناقل: مراجعة حيدر علي سعدي1، نزار قيس محمد نايف الكرخي2*، وسام ثامر عبود3، سومر ناسي4 3،2،1 قسم هندسة التصنيع المؤتمت ، كلية الهندسة الخوارزمي، جامعة بغداد 4 قسم الهندسة الميكانيكية، جامعة ساندي ي غو، كاليفورنيا، الواليات المتحدة االمريكية nazarkais@kecbu.uobaghdad.edu.iqالبريد االلكتروني: * المستخلص مل هذه األنظمة روبوت الرافعة، الذي يُشار إليه غالبًا باسم الروبوت الكارتيزي أو الروبوت الخطي، هو عنصر أساسي في األتمتة الصناعية المعاصرة. تع تتميز الروبوتات الجسرية بتصاميمها .zو yو x على طول مسارات خطية، مما يولد مساحة عمل ثالثية األبعاد باستخدام العديد من المحاور، بما في ذلك نقل المستمر والُمؤتمت الموحدة، مما يجعلها متعددة االستخدامات للغاية للعديد من األغراض. أنظمة النقل الثابت قد أحدثت ثورة في التصنيع من خالل تمكين ال ن المعالجة أو التجميع النهائي، مما يزيد من اإلنتاجية والكفاءة المرن لمزيد مللموارد. تسهل هذه الشراكة االختيار السريع للبضائع، والتحديد الدقيق، والنقل الجسرية الروبوتات تصميم في األهمية غاية في أمور هي الدقيق والتحديد المكاني، والتكوين للجسم، المثالية األبعاد إيجاد تقنيات التشغيلية. في التقدم . عالية والقدرة على التكيف. قياس األبعاد ووضع األجسام هما مهمتان حيويتان تعتمد بشكل كبير على المستشعرات والكاميرات قد عزز بشكل ملحوظ الدقة والف هذه التقنيات شائعة األنظمة المعتمدة على الرؤية، والتي تشمل الكاميرات عالية الدقة والخوارزميات المتطورة للتحليل المكاني. ومع ذلك، على الرغم من أن ن دمج مستشعرات الليزر، وهي خيار محتمل أفضل، ال يزال غير مستكشف بشكل كاٍف. تشير الدقة العالية للغاية لألنظمة القائمة على في المشهد الحالي، فإ جسور، بروبوتات الالليزر في قياس المسافات وتحديد األجسام إلى مجال للبحث المستقبلي. يتناول هذا المقال التطور التاريخي، والمزايا، والعيوب الخاصة كاميرات، وأجهزة مقدماً نظرة شاملة على اإلنجازات المعاصرة في تكنولوجيا القياس والتحديد. يوضح المقال مزايا وعيوب عدة طرق استشعار، بما في ذلك ال زال هناك حاجة إلى حلول مرنة وعالية االستشعار التقليدية، والبدائل الجديدة. على الرغم من التقدم في أنظمة الرؤية لتحديد الهوية وقياس المسافات، ال ي .السرعة يمكن أن تعمل بشكل جيد في البيئات الصناعية الصعبة mailto:%20nazarkais@kecbu.uobaghdad.edu.iq microsoft word '-e/ c'8e111 this is an open access article under the cc by license : al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 17, no. 4, december, (2021) p. p. 111 comparison of prediction programs for short wave circuit link from iraq to test points on both earth hemispheres during solar minimum ahmed kadhim hasan al banna department of information and communication engineering /al khwarizmi college of engineering/ university of baghdad/baghdad/ iraq email: akadhim@kecbu.uobaghdad.edu.iq (received 8 august 2021; accepted 5 october 2021) https://doi.org/10.22153/kej.2021.10.003 abstract this paper compares the accuracy of the hf propagation’s prediction programs for hf circuit links between iraq and different points world wide during august 2018 when solar cycle 24 (start 2009 end 2020) was at minimal activity and also finds out the best communication mode used. prediction programs like the voice of america coverage analysis program and the international telecommunication union recommendation rs 533 had been used to generate high frequency circuit link parameters such as the maximum usable frequency and frequency of transsmision. depending on the predicted parameters (data), real radio contacts had been done using a radio transceiver from icom model ic 7100 with 100w radiated power, tuner box and a homemade dipole antenna 10 meters in length and 8 meters in height above the ground. from the correlation between the predicted data and the observed data, the result was inaccurate. keywords: fot, muf, minimum activity, prediction programs. 1. introduction the sun effects hf radio communication signals that are reflected from the ionosphere layers back to the earth. if the solar flux index (sfi) increases, the layer’s ionization will increase , causing the critical frequencies for these layers to increase too which makes higher frequencies transmitted diffract back to earth again [1]. according to eq(1) as the transmitted frequency increases, the more time it takes to fly in the ionosphere layers before getting refracted back to earth and hence ground distance increases [2,3]. to make a radio contact successfully on hf between two points, if a frequency is greater than the maximum usable frequency ( muf), the signal will penetrate the ionosphere and escape to space and never come back to earth again ,so the working frequency must be less than the muf and is called the frequency of transmission (fot) [4]. the job of the prediction programs is to predict the fot and muf for any circuit link between two points at any time [5]. most of the prediction program results are approximately convergent with points of one hop distance while they diverge (with acceptable error) in points with multiple hop distances, especially in points located near the geomagnetic equator line [5–7]. most of these programs use input variables such as the sun spot number (ssn) , date, geographical location, and the antenna type for prediction [6], and do not use important variables like k and a [8] even though the k parameter represents the status of solar winds. if these solar winds strike the ionosphere, it will result in an increase in the ionization level of the d layer causing an increase in the absorption, fading of sky wave signals, and even block out propagation for extreme solar winds intensity ahmed kadhim hasan al-khwarizmi engineering journal, vol. 17, no. 4, p.p. 111 (2021) 2 [9]. the a parameter is a linear variable that represents the magnetic field of the earth. the previous papers [1-10] focused on the comparison of prediction programs at different geomagnetic circuits and different solar activity without mention to the iraqi hf circuit link, while [11,12] studied the ionospheric parameters for iraq’s zone only when solar winds were at their maximum. the novelty of this work is studying and comparing the propagation prediction for the hf circuit link from iraq to the world at the solar wind’s minimum using the voice of america coverage analysis program (voacap), itu recommendation rs 533 (rec533), and real radio contact during august 2018; and also to find which modulation is preferred digital mode like ft8 [13] or analogue. n = 1 − ( ) …(1) where n is the refraction index, fp is plasma frequency, and f is transmitted frequency. 2. methodology in this paper, the its hf propagation analysis package will be used which includes the voacap, icepac, rec533 and hfant programs. these programs will generate outputs such as the muf, fot, antenna take off angle, reliability of the link (rel), and the antenna analysis (and so on). to use the voacap or rec533 programs as shown in figs. 1 and 2, choose the method of prediction (variables to be predicted like muf,fot,…..etc), set the year , time , groups ( date and sun spot number (ssn)), transmitter and receiver locations, frequency, system parameters, and transmitter receiver antenna (antenna type 23 horizontal dipole will be chosen) . for more information use the “help” page in the program. figs. 3 and 4 show a sample of the program’s results, in which the muf and fot will be predicted at every hour in greenwich mean time (gmt). to simulate the homemade antenna, the hfant program will be used first before the voacap and rec533, so the simulated result will be used in the predicted program for antenna part. fig. 5 shows the program’s interface which is simple to use, just enter the frequency of interest, antenna height, antenna length, and antenna gain. fig. 6 shows the result of the simulation. fig. 1. shows voacap program interface. ahmed kadhim hasan al-khwarizmi engineering journal, vol. 17, no. 4, p.p. 111 (2021) 3 fig. 2. shows rec533 program interface. fig. 3. shows sample of voacap predicted result. fig. 4. shows sample of rec533 predicted result. ahmed kadhim hasan al-khwarizmi engineering journal, vol. 17, no. 4, p.p. 111 (2021) 4 fig. 5. shows hfant program interface. fig. 6.a shows hfant result ( vertical pattern) with maximum beam at 31 deg. ahmed kadhim hasan al-khwarizmi engineering journal, vol. 17, no. 4, p.p. 111 (2021) 5 fig. 6.b shows hfant results (azimuth pattern). fig (6) shows the vertical and azimuth antenna pattern. antenna gain is 2.15 dbi with main beam raised to approximately 31 deg . (in vertical direction) above the ground with the beam width in the azimuth’s direction approximately 270 deg. 3. experiments and results the locations of high frequency (hf) circuit links between iraq and points located on both earth hemispheres shown in table 1 had been studied using prediction programs like voacap and rec533 during may 2014 (where solar cycle 24 was at its maximum and take iraqargantina hf circuit link as example) and august 2018 (when the solar cycle was at its minimum) and the results were summaized on figs. 7-13. these points had been chosen according to their hopping distances (one hop, multi-hop) from iraq and non-arbitrarily. the predicted variables were the maximum usable frequency (muf) and frequency of optimum transmission (fot). a correlation between the predicted muf and the predicted fot that was generated using voacap and rec533 had been done as a measure of accuracy and is summarized in table 2. table 3 summarizes the critical frequency of the f2 layer (fof2) that was generated by using the voacap prediction program (f2pred) for the point (50.1n, 4.6e) dourbes in belgium for 8/1/2018 and the observed fof2 (f2obs) that was recorded using the ionosonde station in dourbes in belgium (50.1n, 4.6e) . a correlation between f2pred and f2obs is summarized in fig. 14. depending on the predicted data from figs. 8 to13, a real radio contact had been done using the radio transceiver from the icom model ic-7100 with 100 w power, single side band (ssb), and a digital modulation mode like the franke–taylor design, 8 fsk modulation (ft8) [13] had been used and a tuner box from mfj model mfj945e as impedance matching box as shown in fig. 15. the antenna was a homemade dipole antenna which was 10 meters long and was rotated manually toward the destination point with a height of 8 m above the ground made with wire with 2.5 mm. in diameter (see fig. 16). table 4 summarizes the contact information that occurred. the mean square error (mse) had been done between the predicted fot (fotpred) from voacap and rec533 and observed fot (fotobs) that get by real radio contact and summarized the result in table 5. ahmed kadhim hasan al-khwarizmi engineering journal, vol. 17, no. 4, p.p. 111 (2021) 6 fig. 7. shows iraqargentina hf circuit link prediction at solar maximum. fig. 7 shows that predictions of using higher bands for skywave radio communication for the iraq-argentina circuit link during solar maximum with the height ionozation level for the ionospher layer (f2) using both voacap and rec533 programs are high. fig. 8. shows iraqantarctica hf circuit link prediction. fig. 8 shows the muf and fot predicted by voacap and rec533, starting with low values and increased with sun rising (increasing of the ionization level of ionosphere layers ) and reached its maximum values at mid day then decreased again at sun set. fig. 8 shows that data predicted by rec533 is higher than voacap predicted data. fig. 9. shows iraq-argentina hf circuit link prediction. fig. 9 shows the muf and fot predicted by voacap and rec533, starting with low values and increases as the sun rises (increasing of ionization level of ionosphere layers ) and it reached its maximum values at mid day then decreased again with the sunset. fig. 9 shows that predictions for the muf and fot values that are generated by rec533 are higher than the voacap predictions. fig. 10. shows iraqgreece hf circuit link prediction. fig. 10 shows the muf and fot predicted by voacap and rec533, starting with low values and increases as the sun rises (increasing of ionization level of ionosphere layers ), it reached its maximum values at mid day then decreased again with the sunset. fig. 10 shows that predictions for the muf and fot values that are generated by voacap are higher than the rec533 predictions. ahmed kadhim hasan al-khwarizmi engineering journal, vol. 17, no. 4, p.p. 111 (2021) 7 fig. 11. shows iraqspain hf circuit link prediction. fig. 11 shows the muf and fot predicted by voacap and rec533. itstarts with low values and increases as the sun rises (increasing of ionization level of ionosphere layers ) and reaches its maximum values at mid day and then decreases again with the sunset. fig. 11 shows that predictions for the muf and fot values that are generated by voacap are higher than the rec533 predictions. fig. 12. shows iraqusa hf circuit link prediction. fig. 12 shows the muf and fot predicted by voacap and rec533, it starts with low values and increases as the sun rises (increasing of ionization level of ionosphere layers ) and reaches its maximum values at mid day then decreases again with the sunset. fig. 12 shows that the predictions for the muf and fot values that were generated by voacap are higher than the rec533 predictions. fig. 13. shows iraqkazakhstan hf circuit link prediction. fig. 13 shows muf and fot predicted by voacap and rec533, starting with low values and increases as the sun rises (increasing of ionization level of the ionosphere layers) and it reached its maximum values at mid day and then decreased again with the sunset. fig. 13 shows that predictions for the muf and fot values that are generated by rec533 are higher than the voacap predictions. fig. 14. showscorrelation between f2pred and f2obs for dourbes –belgium. fig. 14 shows the correlation between the f2pred of fof2 that was predicted by voacap and the f2obs that was measured by the dourbes ionosonde station in belgium during 8/1/2018 for the point (50.1n, 4.6e). the correlation was high, around 0.930752. ahmed kadhim hasan al-khwarizmi engineering journal, vol. 17, no. 4, p.p. 111 (2021) 8 fig. 15. shows icom transceiver model ic-7100 with tuner box from mfj model mfj 945e. fig. 16. shows dipole antenna of 10m long,8m height above groundtable 1 shows hf circuit points geographical locations. table 1, shows hf circuit points geographical locations. test point latitude longitude iraq 32.77n 44.28e antarctica 70.77s 11.79e spain 41.16n 1.10e argentina 32.05s 59.43w greece 37.40n 22.72e kazakhstan 43.64n 51.15e usa 33.65n 112.38w table 2, shows the correlation between rec533 & voacap country muf correlation antartica 0.934212198 spain 0.836102864 argintena 0.25146955 greece 0.994734886 kazakhstan 0.98365713 usa 0.974518472 table 3, shows the fof2 predicted and measured for dourbes in belgium utc fof2 /mhz pred (voacap) obs (dourbes st.) 1 3.84 3.35 2 3.62 2.9 3 3.56 2.75 4 3.7 2.6 5 4.05 3.45 6 4.53 4.35 7 5 4.15 8 5.31 4.45 9 5.47 4.9 10 5.56 4.68 11 5.63 4.9 12 5.62 4.85 13 5.47 4.45 14 5.24 5.23 15 5.08 4.35 16 5.12 4.3 17 5.39 4.63 18 5.77 5 19 6.01 6.01 20 5.97 5.4 21 5.65 4.85 22 5.19 3.95 23 4.69 3.5 24 4.22 3.75 4. discusion from the predicted and observed data, the following notifications had been observed, as follows: the rec533 and voacap programs gave predictions to use high frequency bands for the skywave radio communication hf circuit link between iraq and the world even at the solar cycle’s minimum with solar flux index (sfi) < 70 ( ionozation levels for f2 layer is low). the voacap predictions gave higher predicted values than rec533 at the nothern earth hamsphere except at kazakhstan, while rec533 gave higher predicted values at the southern earth hemisphere. according to table (2) , the two prediction programs had higher correlation values except for the iraq-argentina circuit link (r=0.25146955) because according to fig. 9, the rec533 prediction program’s muf curve had one maximum point that occurred at 16 ut. whereas for voacap the curve had two minimum points that occurred at 10 ut and 17 ut and one maximum point that occurred at 13 ut. the correlation was in this period around (0.21470911) meaning that the rec533 assumes the iraq-argentina circuit link exists in ahmed kadhim hasan al-khwarizmi engineering journal, vol. 17, no. 4, p.p. 111 (2021) 9 the same day zone while voacap assumes the link exist between night–day., day day zone which is more accurate and explains the variance in the two muf/fot curves. according to fig. 14, there is a high correlation (r= 0.930752) between f2pred and f2obs for the dourbes point in belgium [14]. according to table 5, even that the most of the predicted fot failed compared to the observed fot. the rec533 prediction is more accurate than voacap. according to [15], both prediction programs do not include geomagnetic activity variables like k as an input to the prediction. according to table 4, digital mode (ft8) works well (can propagate well ) than analogue mode (ssb) during solar minimum because it has narrow bandwith around 50hz , s/n around 21db and fast its tx/rx simplex transmission round about 15sec. 5. conclusions in this paper, the hf circuits links between iraq and points located on both earth hemispheres with different hops had been studied using voacap and rec533 during august 2018 (solar cycle’s minimum). a correlation between the predicted data that was generated had been done as a measure of accuracy. real radio contacts had been established based on the predicted results using a transceiver from icom model ic-7100 and a 10 meter dipole raised up with 8m rotated manually. most of the fots used in real radio contacts diverge from the fotpred not as a problem in prediction programs algorithms but there was no observed fof2 data given from points like iraq to support the prediction programs models because iraq has no ionosonde station. according to the mse, the rec533 prediction showed more accuracy than the voacap prediction program. during the solar cycle’s minimum with low sun activity, propagation using digital mode (ft8) is better than analogue (ssb) for one hop or more. finally voacap and rec533 will predict with high probability in regions with ionosonde stations like in dourbes, belgium, and predict with low probability with regions with no ionosonde stations like in iraq and the middle east. acknowledgment ahmed kadhim, the author thanks space weather services (sws) of the bureau of methodology /australian government for supporting the research by data (ssn values) used in prediction programs table 4, summarizes the contact information. table 5, shows the mse between real contact data and predicted data station a station b fot pred khz fot obs khz mse voacap khz mse rec533 khz voacap rec533 iraq antarctica 14875 14620 18102.244 16.25756812 9.455438783 spain 13175 8415 7074.1 argentina 12325 11050 14074.961 greece 14110 13515 14200 kazakhstan 11305 12410 18100 usa 13260 13175 14076.6 station a latitude longitude station b latitude longitude date time /utc frequency/ khz mode signal/ dbuv iraq 32.77n 44.28e antarctica 70.77s 11.79e 8/25/2018 14:13 18102.244 digital/ft8 -21 spain 41.16n 1.10e 8/25/2018 22:12 7074.1 digital/ft8 -18 argentina 32.05s 59.43w 8/24/2018 20:14 14074.961 digital/ft8 -4 greece 37.40n 22.72e 8/28/2018 16:20 14200 analogue/ssb 22 kazakhstan 43.64n 51.15e 8/28/2018 7:10 18100 digital/ft8 -19 usa 33.65n 112.38w 8/25/2018 20:11 14076.6 digital/ft8 -3 ahmed kadhim hasan al-khwarizmi engineering journal, vol. 17, no. 4, p.p. 111 (2021) 10 6. references [1] r. athieno, p. t. jayachandran, d. r. themens, and d. w. danskin, “comparison of observed and predicted muf (3000) f2 in the polar cap region,” radio sci., vol. 50, no. 6, pp. 509–517, 2015. [2] australian government ips radio and space services, “introduction to hf radio propagation,” 2010. [online]. available: https://www.sws.bom.gov.au/educational/5 /2/2. [accessed: 04-sep-2021]. [3] c. mudzingwa, a. chawanda,"radio propagation prediction for hf communications",communications,vol 6,no. 1 pp. 5-12,2018 [4] i. bouleanu, m. gheorghevici, and r. helbet, “the quality of the prediction for the nvis propagation with its-hf propagation,” eea electroteh. electron. autom., vol. 64, no. 1, pp. 97–104, 2016. [5] n. insakun, n. wichaipanich, and k. hozumi, “comparison of m (3000)f2 variation between measured data by ionosonde and iri-2016 model data over chiang mai, thailand,” 17th int. conf. electr. eng. comput. telecommun. inf. technol. ecti-con 2020, no. 3000, pp. 197–200, 2020. [6] e. e. johnson, “nvis communications during the solar minimum,” in milcom, military communications conference, 2007, pp. 1–5. 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[11] k. a. hadi,l. e. goerge ," a simplied mathematical model to calculate the maximum usable frequencies over iraqi territory", diyala journal for pure sciences,vol 7, no. 4 ,pp 120,2011. [12] a. z. aziz , k. a. hadi, "determination of ionospheric parameters over iraqi zone", iraqi journal of science, vol 54, no.2, pp 475-484, 2013. [13] dale burmester, “amateur radio digital communication mode ft8,” 2019. [online]. available: http://site.ieee.org/msn/files/2019/04/ft8ka9swe.pdf. [accessed: 07-sep-2021]. [14] s. g. tanyer , c. b. erol,” comparison of the current method s for coverage area prediction for communication in the hf band”, ieee antenna and propagation society international symposuim,1998. [15] a. j. stocker, m. muriuki, e. m. warrington,” comparision of obliques sounding measurements and voacap [16] predictions on a mid – latitude path”, the institution of engineering and technology 11th international conferrenceon ionosperic radio systems and techniques, 2009. ) 2021( 111، صفحة 4العدد ، 17مجلة الخوارزمي الهندسية المجلد حسن احمد كاظم 11 برامج التوقع لمسارات دوائر الموجات القصيره من العراق الى نقاط اختبار على ةمقارن جانبي نصفي الكره االرضيه خالل الدوره الشمسيه الصغرى احمد كاظم حسن قسم هندسة المعلومات واالتصاالت/ كلية الهندسة الخوارزمي/ جامعة بغداد akadhim@kecbu.uobaghdad.edu.iqالبريد االلكتروني: ةالخالص عندما الدوره الشمسيه ٢٠١٨خالل الشهر الثامن ةبرامج التوقع لمسارات دوائر الموجات القصيره بين العراق ونقاط مختلف ةهذا البحث يقارن دق :) كانت عند اقل نشاط وكذلك ايجاد افضل نمط اتصال مستخدم. برامج التوقع متل٢٠٢٠وانتهت ٢٠٠٩( بدات ٢٤ voice of america coverage analysis program (voacap) and itu recommendation rs 533 (rec533) متغ لتوليد دائراستخدمت مسار عمل ةالقصير ةالموج ة يرات تم (البيانات) المتغيرات هذه على باالعتماد العامل. والتردد مستخدم تردد اعظم متل من شرك باستخدام السلكي راديوي موديل ةاتصاالت بطول ١٠٠بقدره ٧١٠٠ايكوم يدوي دايبول صنع مؤائمه وهوائي متر ١٠واط و صندوق .ةالنتائج كانت غير دقيق ةالتطابق بين البيانات المتوقعه و البيانات المقاس ةاالرض. من عملي متر عن مستوى ٨وارتفاع دراسة تأثير أختلاف جرع التعرض لاشعة ذات طاقة عالية على بعض 1 al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 5, no. 2, pp 72 -82 (2009) ٌّادج ِرشاوثح ِٓ دساسح ذأثٍش اخرالف اٌجشع اإلشؼاػٍح ػٍى تؼغ اٌخظائض اٌٍّىأٍىٍح اٌشاذٕج إٌىفىالن ِرؼشػح ألشؼح راخ ؽالح ػاٌٍح ***ِحّذ َطالب حّضج ** ِضهش ػًٍ طاحة * سوال ػثذ اٌخؼش ػثاط اٌغبِؼخ اٌزىٌٕٛٛع١خ / قسم العلوم التطبٌقٌة * اٌغبِؼخ اٌزىٌٕٛٛع١خ/ حلغُ ٕ٘ذعخ اٌىٙش١ِٚىب١ٔىٟ ** اٌغبِؼخ اٌزىٌٕٛٛع١خ/ لغُ ٕ٘ذعخ اٌّٛاد *** (received 23 march 2008; accepted 2 june 2009) اٌخالطح ث١ّٕب اعزؼٍّذ أ١ٌبف اٌضعبط , وّبدح أعبط ٌٍّبدح اٌّزشاوجخ (ٔٛفٛالن) فٛسِبٌذ٠ٙب٠ذ ٔٛع -رؼّٕذ ٘زٖ اٌذساعخ رؾؼ١ش ِبدح ِزشاوجخ ِٓ سارٕظ اٌف١ٕٛي method)وّب اعزخذَ ؽش٠مخ اٌزششة , (%60)ج ٚلذ وبٔذ ٔغجخ اٌىغش أٌٛصٟٔ ٌأل١ٌبف رمذس . ثشىً أ١ٌبف لظ١شح وّٛاد ِم٠ٛخ (e-glass)ٔٛع impregnation) ِب إٌّجؼضخ ِٓ گبٚأْ ٘زٖ اٌّبدح اٌّزشاوجخ اٌّؾؼشح ُشؼؼذ ثأشؼخ . فٟ رؾؼ١ش ٘زٖ اٌّبدح اٌّزشاوجخ ثبعزؼّبي اٌمٌٛجخ ثّىبثظ اٌؼغؾ kgy(728 ,312,208 .)ٚثغشع أشؼبػ١ٗ ِخزٍفخ ٟ٘ (1.25mev)راد ِؼذي ؽبلخ (co60)إٌظ١ش اٌّشغ ِغ (اٌظالدح اٌغطؾ١خ ٚ ِمبِٚخ اٌظذِخ, ِمبِٚخ اٌمض اٌذاخ١ٍخ, ِزبٔخ اٌضٕٟ, االٔؾٕبء)ِٚٓ صُ رّذ ِمبسٔخ خٛاص ٘زٖ اٌّبدح اٌّزشاوجخ اٌّزّضٍخ ثفؾض . رٍه اٌخٛاص ٌٙزٖ اٌّبدح اٌّزشاوجخ غ١ش اٌّشؼؼخ ٚرٌه ٌّالؽظخ رأص١ش اٌزشؼ١غ ػٍٝ اٌّمبِٚخ اإلشؼبػ١خ ٌٙزٖ اٌّبدح kgy(312 ) ٚأْ ص٠بدح اٌغشع اإلشؼبػ١خ إٌٝ, أظٙشد إٌزبئظ اٌّمبسٔخ إْ رذػ١ُ اٌشارٕظ إٌٛفٛالن ثأ١ٌبف اٌضعبط ٠ؼًّ ػٍٝ رؾغ١ٓ ِمبِٚزٗ اإلشؼبػ١خ . رؤدٞ إٌٝ ص٠بدح ع١ّغ اٌخظبئض ا١ٌّىب١ٔى١خ اٌّذسٚعخ فٟ ثذا٠خ األِش ٌزٕخفغ ثؼذ رٌه ٘زٖ اٌخظبئض ِغ االعزّشاس ثض٠بدح اٌغشع اإلشؼبػ١خ . ٘زا ِٚٓ اٌغذ٠ش ثبٌزوش رُ االعزؼبٔخ ثبٌّغٙش االٌىزشٟٚٔ اٌؼٛئٟ ٌذساعخ اٌغّبد اٌغطؾ١خ ٌٍّٕبرط اٌخبػؼخ ٌجؼغ ِٓ اٌفؾٛطبد اٌغبثمخ اٌزوش معامل , األشعة المؤٌنة , الجرع اإلشعاعٌة, التشعٌع بأشعة كاما, راتنج النوفوالك, المواد المتراكبة الفٌنولٌة, المقاومة اإلشعاعٌة: اٌىٍّاخ اٌّفراحٍح الصالدة, مقاومة الصدمة, مقاومة الثنً, المرونة اٌّمذِح. 1 لذ شبع اعزخذاَ اٌّٛاد اٌّزشاوجخ راد اٌٛعؾ اٌف١ٌٕٟٛ (phenolic) فٟ اغٍت اٌزظ١ّّبد اٌؾذ٠ضخ ٔظشاً ٌزفٛق خٛاطٙب فٕٙبن رطج١مبد ػذ٠ذح ثشصد , اٌؾشاس٠خ ػٍٝ ثم١خ اٌّٛاد اٌشارٕغ١خ ف١ٙب اٌؾبعخ إٌٝ ِٛاد راد لبث١ٍخ ػب١ٌخ ػٍٝ رؾًّ دسعبد اٌؾشاسح radiation)اٌّشرفؼخ إصٕبء رؼشػٙب ألشؼخ راد ؽبلخ ػب١ٌخ energy high -) , وّب ٘ٛ اٌؾبي فٟ اٌؼذ٠ذ ِٓ اٌذٚائش equipment)اٌىٙشثبئ١خ اٌّغزؼٍّخ فٟ رغ١ٙضاد اٌمذسح ا٠ٌٕٚٛخ voltage high -) ٚوّبعىبد ٌٍّٛاد اٌّشؼخ خالي األعٙضح فٟ ِٕشبد (coatings protective)ا٠ٌٕٚٛخ أٚ وطالءاد ٚلبئ١خ .[1]ر١ٌٛذ اٌمذسح ا٠ٌٕٚٛخ , ِبگبأشؼخ )ک أْ رؼشع اٌج١ٌّٛشاد ألشؼخ راد ؽبلخ ػب١ٌخ االٌىزشٚٔبد , (neutrons)ا١ٌٕٛرشٚٔبد , األشؼخ اٌغ١ٕ١خ (electrons) , اٌجشٚرٛٔبد(protons) ٚاٌذ٠زشٚٔبد (deuterons)) ٠ؤدٞ إٌٝ ؽذٚس ػ١ٍّبد رأ٠ٓ ٚر١ٙظ ٌٍغض٠ئبد ٚثبٌزبٌٟ اٌؾظٛي ػٍٝ عض٠ئبد ِز١ٙغخ ٚأ٠ٛٔبد ِٚٓ صُ ٠ؤدٞ إٌٝ إٔزبط اٌغزٚس اٌؾشح ٚأْ ػذد اٌغزٚس اٌؾشح إٌبرغخ ٠زٕبعت . [1] [2]ِغ عشػخ اٌزشؼ١غ ٚعذ٠شاً ثبٌزوش أْ ٘زٖ اٌغزٚس سثّب رزفبػً ٚرغ١ش ِٓ اٌزشو١ت اٌى١ّ١بئٟ ٌٍج١ٌّٛش ٚثبٌزبٌٟ فأٔٙب رغ١ش ِٓ اٌخٛاص . [3]اٌف١ض٠بئ١خ ٌٍج١ٌّٛش ٚػ١ٍٗ أعش٠ذ اٌؼذ٠ذ ِٓ اٌذساعبد اٌزٟ رجؾش فٟ ِٛػٛع رأص١ش األشؼخ اٌّؤ٠ٕخ ػٍٝ اٌخٛاص اٌف١ض٠بئ١خ ٌٍؼٛاصي اٌىٙشثبئ١خ ( zahrani)لبَ اٌجبؽضبْ (1979)ففٟ ػبَ , اٌج١ٌّٛش٠خ ٚ(nofal) ثذساعخ رأص١ش رشؼ١غ ثٌٟٛ وٍٛس٠ذ اٌفب١١١ًٔ ثأ٠ٛٔبد ا١ٌٙذسٚع١ٓ ٚثفزشاد ص١ِٕٗ ِخزٍفخ ٚطٍذ إٌٝ صّب١ٔخ أ٠بَ فٛعذ رمً فٟ ( ِزاة فٟ عب٠ىٛ٘ىغبpvcْٛٔ)أْ ٌضٚعخ اٌّؾٍٛي . [4]اٌّشاؽً األٌٚٝ ِٓ اٌزشؼ١غ ٚثؼذ٘ب رضداد ل١ّخ اٌٍضٚعخ أعش٠ذ رغبسة ِٓ لجً اٌؼب١١ٌّٓ (1981)ٚفٟ ػبَ (klabunde) ٚ (coltman) ؽ١ش ػٍّٛا ػٍٝ رشؼ١غ اال٠جٛوغٟ ٚاٌجٌٟٛ أِب٠ذ اٌذاخٍخ فٟ طٕبػخ اٌّزشاوجبد ثأشؼخ 4.9)وبِب ٚفٟ دسعخ ؽشاسح 0 k) ٚاخؼؼٛا ٘زٖ اٌّزشاوجبد فؾض , فؾض اٌضٕٟ رٚ إٌمبؽ اٌضالصخ)اٌّشؼؼخ ٌفؾٛص ١ِىب١ٔى١خ 77)ٚفٟ دسعخ ؽشاسح (االٔؼغبؽ 0 k, 300 0 k) ٖخالي ٘ز ِٓٚ اٌفؾٛطبد اعزٕزغٛا إْ ٕ٘بن أؾذاس فٟ ل١ّخ ألظٝ ِمبِٚخ 77)أضٕبئ١خ ٌشارٕظ اال٠جٛوغٟ ٚاٌجٌٟٛ اِب٠ذ ػٕذ ؽشاسح 0 k, 300 0 k ) ٚػٕذ اٌّمبسٔخ ث١ٓ اٌشارٕغ١ٓ رٛطٍٛا إٌٝ إْ سارٕظ . [5]اٌجٌٟٛ اِب٠ذ ٘ٛ أوضش ِمبِٚخ ِٓ سارٕظ اال٠جٛوغٟ الشؼخ وبِب أعش٠ذ رغبسة ِٓ لجً اٌؼبٌُ (1983)ٚفٟ ػبَ (balakrishna) عّبػزٗ ؽ١ش لبِٛا ثزشؼ١غ ِزشاوت ٚ اال٠جٛوغٟ اٌّغٍؼ ثبأل١ٌبف اٌضعبط ثأشؼخ وبِب ِمذاس٘ب (10 8 rad) ؽ١ش ػٍّٛا ػٍٝ إعشاء فؾض اٌىالي(fatigue ) 77)ٚفٟ دسعزٟ ؽشاسح (٘ٛ أؽذٜ اٌفؾٛص ا١ٌّىب١ٔى١خ) 0 k 82 72، طفحح 2، اٌؼذد 5ِجٍح اٌخىاسصًِ اٌهٕذسٍح اٌّجٍذ سوال ػثذ اٌخؼش ػثاط (200 9) 73 ,295 0 k) ػٍٝ اٌزٛاٌٟ ٚوبْ ٌزأص١ش دسعبد اٌؾشاسح إٌّخفؼخ . [6]ص٠بدح ِمبِٚخ اٌىالي ٌٍّزشاوجبد اٌّشؼؼخ ٚ عّبػزٗ ثزشؼ١غ (egusa)لبَ اٌجبؽش (1984)ٚفٟ ػبَ ِزشاوجبد اال٠جٛوغٟ ِٚزشاوجبد اٌجٌٟٛ اِب٠ذ ٚوً ِزشاوت ِٓ اٌضعبع١خ ٚاٌىبسث١ٔٛخ )٘زٖ اٌّزشاوجبد ِغٍؼ ثئؽذٜ األ١ٌبف ٚشؼؼذ ثأشؼخ وبِب ٚاٌف١غ ا١ٌٕٛرشٟٚٔ ٚفٟ دسعخ (ٚاأل١ٌَّٕٛ فؾض اٌضٕٟ )ؽشاسح اٌغشفخ ٚأعش٠ذ ػ١ٍٙب اٌفؾض ا١ٌّىب١ٔى١خ 5)فٟ دسعخ اٌغشفخ ٚفٟ دسعخ ؽشاسح (رٞ إٌمبؽ اٌضالس 0 k ) رٛطٍٛا إٌٝ أْ ِؼبًِ ٠ٛٔه ٌٙزٖ اٌّزشاوجبد ٌُ ٠زغ١ش إال فٟ 10×5)اٌف١غ ا١ٌٕٛرشٚٔبد 18 n/cm 2 ٚ أْ ألظٝ ِمبِٚخ ( أضٕبئ١خ فٟ ٘زا اٌف١غ ٚفٟ دسعخ ؽشاسح اٌغشفخ رمً أ٠ؼب ٌّزشاوت اال٠جٛوغٟ اٌّغٍؼ ثبأل١ٌبف اٌضعبع١خ أِب ٌجم١خ اٌّزشاوجبد فأْ ِؼبًِ ٠ٛٔه ٚألظٝ ِمبِٚخ أضٕبئ١خ ٌُ رزأصش فٟ ؽبٌزٟ أشؼخ وبِب ٚا١ٌٕٛرشٚٔبد فّؼبًِ ٠ٛٔه ٠جمٝ غ١ش ِزغ١ش أال [7].(mrad 1000)فٟ ؽذٚد عشػٗ ِمذاس٘ب ( duplessis)دسط اٌجبؽضبْ (1988)ٚفٟ ػبَ ٚ(badenhorst()5) ِب ػٍٝ طالدح ِبدح ثٌٟٛ گبرأص١ش أشؼخ ٚاٌّغزؼٍّخ (%5)وٍٛس٠ذ اٌفب١١ًٔ اٌّؼبفخ إ١ٌٗ اٌّطبؽ ثٕغجخ وأسػ١بد ٌٍّٕبصي فٛعذ أْ اٌظالدح رضداد ثظٛسح ؽف١فخ ػٕذ ِمبسٔخ ثبٌج١ٌّٛش غ١ش (300kgray)اٌغشػخ اإلشؼبػ١خ . [8]اٌّشؼغ ٚعّبػزٗ ثذساعخ (aytac)لبَ اٌجبؽش (2007)ففٟ ػبَ ( high tenacity)رجؾش اِىب١ٔخ اٌؾظٛي ػٍٝ ِزبٔخ ػب١ٌخ ٚاٌجٌٟٛ nylon66 ( ny66)ِٓ إٌب٠ٍْٛ (cords)ألششؽخ اٌّغزؼٍّخ فٟ اؽبساد اٌغ١بساد polyester( pet)اعزش (tyres autombile) ٚرٌه ثزؼشع ٘زٖ األششؽخ اٌج١ٌّٛش٠خ ( cords tyre)ٚػ١ٍٗ فأْ أششؽخ اإلؽبس اٌّؼذٟٔ , ألشؼخ وبِب ِخزٍفخ لذ شؼؼذ ثّؼذالد (levels twist)راد ِغز٠ٛبد ثشَ فمذ ٚعذ أْ اصش اٌزشؼ١غ ػٍٝ وً ِٓ . عشع ِخزٍفخ فٟ اٌٙٛاء ال رؼزّذ ػٍٝ ِغز٠ٛبد اٌجشَ ٌٙزٖ (pet)ٚ (ny66)أششؽخ ٚعذ٠شاً ثبٌزوش أْ اٌزغ١ش فٟ ثؼغ . األششؽخ اٌّؾؼشح اٌخظبئض ا١ٌّىب١ٔى١خ ٚاٌؾشاس٠خ ِغ ص٠بدح اٌغشع اٌّّزظخ لذ رُ وً ِٓ ( deteriorate)فمذ ٌٛؽع ؽظٛي رذ٘ٛس . ل١بعٙب ( strength tensile)ِٚمبِٚخ اٌشذ (elongation)االعزطبٌخ ِغ ص٠بدح اٌغشع اإلشؼبع ث١ّٕب ٌُ ٠طشأ إٞ (ny66)ألششؽخ وّب أْ ل١ّخ االٔىّبػ اٌؾبس . (cords pet)رغ١ش فٟ أششؽخ (shrinkage hot) ٌ (ny66 greige) ٕٝلذ رؾغٕذ أٞ ثّؼ ( pet greige)أْ ٘زٖ إٌمظبْ ٠ىْٛ الً ثىض١ش فٟ . لٍذ ٚػ١ٍٗ اعزٕزظ اٌجبؽش أْ أششؽخ (cords ny66)ج ِمبسٔخ (cords (pet ٗراد ِمبِٚٗ أشؼبػ١ (resistance radiation) أششؽخ جِمبسٔخ(cords ny66) , ٚاْ آصبس ػٍٝ أششؽخ (irradiation energy)اسرفبع ؽبلٗ اٌزشؼ١غ اٌزٟ ٠ٕجغٟ أخز٘ب ثٕظش االػزجبس (cords tyre)اإلؽبس اٌّؼذٟٔ ( vulcanization – pre)خالي اٌزظ١ُّ إرا ِب ؽجك ػٍٝ اٌفٍىٕٗ . [9]ؽبلخ ػب١ٌخ اإلشؼبع ٚعّبػزٗ (saenpong)لبَ اٌجبؽش (2008)ٚفٟ ػبَ ( ipp)ثذساعخ ثؼغ اٌخظبئض ٌّبدح ِزشاوجخ ِٓ سارٕظ (propylene isotatic poly) اٌّمٜٛ ثبأل١ٌبف اٌطج١ؼ١خ (fibers natural) اٌّزّضٍخ ثٕشبسح اٌخشت(sawdust wood ) ٚلذ اعزخذِذ ِبوٕخ اٌجضك , (%wt 30)ج ثٕغجخ ٚص١ٔخ رمذس فٟ رؾؼ١ش طفبئؼ (extruder screw twin)اٌضٕبئ١خ اٌٌٍٛت ثؼذ٘ب اعزؼٍّذ ِبوٕخ ؽمٓ اٌمٛاٌت , (ipp)ِجضٛلخ ِٓ سارٕظ (machine molding injection) إلػذاد إٌّبرط اٌّزشاوجخ . ؽج١ؼ١خ٘زا ٚلذ دسط اٌجبؽش ٚعّبػزٗ رأص١ش ظشٚف اٌزغ٠ٛخ اي (weathering natural) ٚاٌغّش ثبٌّبء(immersion water) ٚاٌزشؼ١غ ثأشؼخ وبِب(irradiation ray-gamma ) . ػٍٝ اٌخٛاص ا١ٌّىب١ٔى١خ ٌٙزٖ اٌّبدح اٌّزشاوجخ اٌّؾؼشح ٌٚمذ اعزٕزظ اٌجبؽش ٚعّبػزٗ أْ خبط١خ اٌشذ رزؾغٓ ِغ weathering )اٌض٠بدح االثزذائ١خ ٌضِٓ اٌزؼشع ٌٍزغ٠ٛخ اٌطج١ؼ١خ natural) ٌٝ٠ِٛبً ثؼذ رٌه أخفؼذ ٚثبٌّضً فأْ ِمبِٚخ (30)إ modulus)ِٚؼبًِ ٠ٛٔه (strength tensile)اٌشذ young's) رضداد ِغ اٌض٠بدح االثزذائ١خ ٌٍغشع اإلشؼبػ١خ صُ ثؼذ فأْ ػٕذ اٌىغش ال رزغ١ش ٘زٖ , ػٍٝ اٌؼىظ ِٓ رٌه,رٌه رمً أ٠ؼب ً ٠َٛ (15)اٌخٛاص ٌٍّبدح اٌّزشاوجخ ثؼذ غّش٘ب فٟ اٌّبء ٌّٚذح . ٌٚىٕٙب عشػبْ ِب رشٙذ ص٠بدح ثؼذ رٌه وّب أشبسد ٘زٖ اٌذساعخ إٌٝ ؽم١مخ أْ ٘زٖ اٌزغ١شاد اٌؾبطٍخ فٟ خٛاص ٘زٖ اٌّبدح اٌّزشاوجخ اٌّؾؼشح ٠فزشع ٔز١غخ ٌٍزأصش ٚرفبػالد (linking-cross )اٌّزجبدي ث١ٓ اٌزشبثه اٌزشاثطٟ ٚاٌزٟ رؾذس رؾذ ظشٚف (scission chain)أفالق اٌغٍغٍخ اٌزغ٠ٛخ اٌطج١ؼ١خ ٚاٌزشؼ١غ ثأشؼخ وبِب ثبإلػبفخ إٌٝ ػ١ٍّبد ثزأص١ش اِزظبص عض٠ئبد اٌّبء خالي (plasticizing)اٌزٍذ٠ٓ . [10]غّش إٌّبرط اٌّؾؼشح ف١ٗ اٌهذف ِٓ اٌذساسح. 2 رٙذف ٘زٖ اٌذساعخ ٌٍزؼشف ػٍٝ االصبس اٌغبٔج١خ ألشؼخ وبِب co)ٚوزا اٌغشع اإلشؼبػ١خ إٌبرغخ ِٓ إٌظ١ش اٌّشغ 60 ػٍٝ ( ثؼغ اٌخٛاص ا١ٌّىب١ٔى١خ ٌّزشاوت ث١ٌّٛشٞ ٠زأٌف ِٓ سارٕظ اٌف١ٕٛي ــ فٛسِبٌذ٠ٙب٠ذ ٔٛع ٔٛفٛالن اٌّذػُ ثأ١ٌبف اٌضعبط ِٚؼشفخ ِذٜ االٔؾشاف اٌؾبطً فٟ , (%60)ٚثىغش ٚصٟٔ لذسٖ خظبئظٗ ا١ٌّىب١ٔى١خ ِغ اسرفبع ل١ّخ اٌغشػخ ِٓ اإلشؼبع ٌزؾذ٠ذ اٌّخبؽش إٌبعّخ ػٓ رشاوُ ٘زٖ اإلشؼبػبد فٟ , إٌٛٚٞ عغُ اٌّزشاوت ثغ١خ رمذ٠ش خطٛسرٙب ػٍٝ وفبءح أداء اٌّبدح . اٌّؾؼشح اٌجأة إٌظشي. 3 (ray gammaِا گاأشؼح ) 3.1 ِب ػٍٝ األشؼخ اٌىٙشِٚغٕبؽ١غ١خ إٌبرغخ گبرطٍك رغ١ّخ أشؼخ ػٓ اٌزؾٛالد اٌؾبدصخ فٟ إٌٛاح فٟ ؽبٌخ ر١ٙظ فزجؼش ؽبلخ اٌز١ٙظ ٘زٖ ٌىٟ رؼٛد إٌٝ ؽبٌخ اٌّغزمشح ػٍٝ شىً أِٛاط وٙشِٚغٕبؽ١غ١خ ٟٚ٘ راد ؽٛي ِٛعٟ لظ١ش عذاً ٠زشاٚػ 10×3)ث١ٓ -8 –10 -10 cm) رّزبص ثمبث١ٍزٙب اٌىج١شح عذاً ػٍٝ اخزشاق . [11] [25]اٌّٛاد (sources ray gammaِا گاِظادس أشؼح ) 3.2 -:[26] [27]ِب رجؼبً ٌّظبدس٘ب إٌٝ ِب٠ٍٟگبرمغُ أشؼخ decay)ِب اٌزٟ رٍٟ أؾالي ث١زب أٚ إٌفب ِٓ إٌٛاح گب أشؼخ 1alpha beta or following gamma – ray .) (. radiation annihilation) أشؼبع اٌفٕبء 2(. bremsstrahlung) (اٌزجبؽؤ) أشؼخ اٌىجؼ 3 .ِب إٌبرغخ ِٓ اٌؼ١ٍّبد ا٠ٌٕٚٛخگب أشؼخ 4 82 72، طفحح 2، اٌؼذد 5ِجٍح اٌخىاسصًِ اٌهٕذسٍح اٌّجٍذ سوال ػثذ اٌخؼش ػثاط (200 9) 74 فٕٙبن أٔٛاع ِخزٍفخ ِٓ اٌّظبدس اإلشؼبػ١خ اٌّغزخذِخ فٟ ( isotopes radioactive)رشؼ١غ اٌج١ٌّٛش ِٕٙب إٌظبئش اٌّشؼخ . [12]ِٚؼغالد اٌغغ١ّبد اٌّشؾٛٔخ – 60ٚأْ ِٓ اٌغذ٠ش ثبٌزوش اعزخذَ إٌظ١ش اٌّشغ اٌىٛثٍذ (co 60 ِب إٌّجؼضخ ِٓ گبفٟ أثؾبس رشؼ١غ اٌج١ٌّٛشاد ألْ أشؼخ ( (co 60 رظً فٟ األلً إٌٝ ػذح عٕزّزشاد داخً اٌّٛاد ( فٙٛ ٠جؼش . اٌج١ٌّٛش٠خ ٚرزفبػً ِغ أغٍت االٌىزشٚٔبد اٌزس٠خ ٚاألخش (1.17mev)ِب أؽذّ٘ب رٚ ؽبلخ گبفٛر١ٔٛٓ ألشؼخ (1.33mev) .ٛٙعٕخ (5.26)أِب ػّش ٔظف ٌٗ ف [13] . ِٚٛػٛع ٘زٖ اٌذساعخ ٠شرجؾ ثزشؼ١غ اٌّبدح اٌّزشاوجخ ِب فٟ دسعخ ؽشاسح اٌغشفخ ثبعزخذاَ گباٌّؾؼشح ثأشؼخ co)ِظذس 60 .) interaction ofِا ِغ اٌّادج گاذفاػً أشؼح 3.3 gamma with matter radiation ِب ػٕذ ِشٚس٘ب خالي اٌّبدح رجؼبً ٌطبلزٙب ِغ گبرزفبػً أشؼخ -:االٌىزشٚٔبد اٌزس٠خ ثطشائك ِخزٍفخ ٚوّب ٠ٍٟ (. effect photoelectric) اٌزأص١ش اٌىٙشٚػٛئٟ 1(. effect compoton) رأص١ش وِٛجزٓ 2 production )(االٌىزشٚٔبد ٚاٌجٛصرشٚٔبد) إٔزبط األصٚاط 3piar.) ثبإلػبفخ ٌٙزٖ اٌزفبػالد اٌشئ١غ١خ اٌضالص١خ رٛعذ رفبػالد أخشٜ ١ٌغذ راد أ١ّ٘خ فٟ ِغبي ٘زٖ اٌذساعخ ٌؼذَ اؽزّب١ٌخ ؽذٚصٙب فٟ ِذٜ اٌطبلخ اٌّذسٚعخ [11] . effect of ِا ػٍى اٌثىٌٍّشگاذأثٍش أشؼح 3.4 radiation on polymer gamma ِب ػٍٝ اٌج١ٌّٛش ٠زّضً فٟ أؽذاس رأ٠ٓ ٚر١ٙظ گبأْ رأص١ش أشؼخ ِٚٓ صُ . فٟ عض٠ئبرٗ ثبٌزفبػالد اٌزس٠خ اٌّج١ٕخ فٟ اٌفمشح اٌغبثمخ أٚ ا٠ٛٔبد ٚعزٚس ؽشح (radicals free)رى٠ٛٓ عزٚس ؽشح ِب ػٍٝ اٌج١ٌّٛشگب٠ٛػؼ رأص١ش أشؼخ (1)ٚاٌشىً [28] . . [28]ػٍى اٌثىٌٍّشگاّا ٌىػح ذأثٍش أشؼح -1-شىً ٌزا فأْ , ؽ١ش ٠ىْٛ اٌؼّش اٌضِٕٟ ٌأل٠ٛٔبد إٌبرغخ لظ١شاً اٌغزٚس اٌؾشح ٟ٘ اٌزٟ رذخً فٟ اٌزفبػالد اٌى١ّ١بئ١خ اٌزٟ ٠طٍك ٚثزٌه (radiochemical)ػ١ٍٙب اٌزؾٛالد اإلشؼبػ١خ اٌى١ّ١بئ١خ فأْ اٌزغ١ش اٌؾبطً فٟ اٌخٛاص اٌف١ض٠بئ١خ ٌٍج١ٌّٛش اٌّؼشع . [14]ِب ٔبرظ ػٓ اٌزشر١ت االٌىزشٟٚٔ اٌغذ٠ذ ٌغض٠ئبرٗگبألشؼخ ٚأْ ١ِىب١ٔى١خ رفبػالد اٌغزٚس اٌؾشح ِغ ثؼؼٙب ٠ىْٛ ػٍٝ -:[3][15]ٔٛػ١ٓ ّ٘ب scission( degrading) (اٌزؾًٍ) عؾك اٌغٍغٍخ اٌشئ١غ١خ 1chain main : . ٟٚ٘ ػ١ٍّخ رم١ًٍ ؽٛي اٌغٍغٍخ اٌشئ١غ١خ ٌٍغش٠ئخ اٌج١ٌّٛش ِب أرا وبٔذ گبثظٛسح ػبِخ ٠زؾًٍ اٌج١ٌّٛش ػٕذ رؼشػٗ ألشؼخ اٌٛؽذح اٌزشو١ج١خ ٌٗ رؾزٛٞ ػٍٝ ِغّٛػز١ٓ عبٔج١ز١ٓ وج١شر١ٓ (groups side large two.) (: linking cross) اٌزشبثه اٌزشاثطٟ 2ِب فٟ اٌؼذ٠ذ ِٓ اٌج١ٌّٛشاد خٍغ اٌّغب١ِغ گبرغجت أشؼخ اٌغبٔج١خ ربسوخ عش٠ئخ اٌج١ٌّٛش ثشىً عزس ؽش ِّىٓ أْ ٠زفبػً .صب١ٔخ ٚثزٌه فأْ ص٠بدح اٌزشبثه اٌزشاثطٟ ٠ؤدٞ إٌٝ ص٠بدح اٌٛصْ . اٌغض٠ئٟ ٌٍج١ٌّٛش ٚأخفبع فٟ لبث١ٍخ رٚثبٔٗ ذشخٍض وذىطٍف اٌّماوِح إالشؼاػٍح ٌٍثىٌٍّشاخ 3.5 وِرشاوثرها ثظٛسح ػبِخ أْ ِذٜ اٌزغ١ش اٌؾبطً فٟ اٌزشو١ت اٌى١ّبئٟ ٌٍج١ٌّٛشاد ِٚزشاوجبرٙب ثفؼً األشؼخ راد اٌطبلخ اٌؼب١ٌخ ٘ٛ ِم١بط ؽ١ش أْ ِذٜ االٔؾشاف اٌؾبطً فٟ , ٌّمبِٚزٙب إالشؼبػ١خ اٌخٛاص ا١ٌّىب١ٔى١خ ٚاٌىٙشثبئ١خ ٚاٌؾشاس٠خ ٌٙزٖ اٌّٛاد خالي [1]رؼشػٙب ٌّؾ١ؾ ِٓ األشؼخ ا٠ٌٕٚٛخ ٠ؾذد ؽج١ؼخ اعزخذاِٙب [3] . ٚفٟ ٘زٖ اٌذساعخ رُ رٛط١ف اٌّمبِٚخ اإلشؼبػ١خ ٌٍّبدح -:اٌّزشاوجخ اٌّؾؼشح ثأعشاء االخزجبساد ا١ٌّىب١ٔى١خ اٌزب١ٌخ test bending and) اخزجبس االٔؾٕبء ِٚزبٔخ اٌضٕٟ -:أوالًال strength flexural:) (test bending)اخزجبس االٔؾٕبء -أ ٠ؼذ ٘زا االخزجبس ِٓ االخزجبساد اٌّّٙخ ٚاٌّؼمذح ٌىٛٔٗ ٠زؼّٓ اٌزؼشع ٌٕٛػ١ٓ ِٓ اٌمٜٛ األٌٚٝ لٛح اٌؼغؾ (compression) ٚاٌضب١ٔخ لٛح شذ(tension) [29] . فّٓ خالي ٘زا اٌفؾض ٠ّىٓ ِؼشفخ اٌزغ١ش فٟ االٔؾشاف رؾذ رأص١ش ؽًّ ِزغ١ش ٚثزٌه ٠ّىٓ ؽغبة ِؼبًِ ِشٚٔخ اٌضٕٟ خالي اٌغضء اٌجذائٟ ِٓ ()اٌغغبءح(ٚاٌزٞ ٠ّضً ِم١بط اٌظالثخ ) -: [29]ػ١ٍّخ اٌضٕٟ ثبعزخذاَ اٌؼاللخ اٌزب١ٌخ              i gl deflection mass e 48 3 … (1) رّضً ١ًِ اٌغضء اٌخطٟ ِٓ ِٕؾٕٝ : (deflection/mass)ؽ١ش . ( االٔؾٕبء-اٌؾًّ) ( l) : ًاٌجؼذ ث١ٓ ٔمطٟ اٌزؾ١ّ(m .) γradiation polymer molecule + high energy electron ion thermalization of electron and trapping by ion excited molecule main chain rupture side chain rupture free radicals * 82 72، طفحح 2، اٌؼذد 5ِجٍح اٌخىاسصًِ اٌهٕذسٍح اٌّجٍذ سوال ػثذ اٌخؼش ػثاط (200 9) 75 ( i) : ٠ّضً ػضَ االٔؾٕبء إٌٙذعٟ ٚاٌزٞ ٠ؼطٝ ثبٌّؼبدٌخ اٌزب١ٌخ [20] : 12 3bd i  … (2) (. m)ػشع إٌّٛرط : (b)ؽ١ش ( d) : عّه إٌّٛرط(m .) (strength flexural (.f.s))اخزجبس ِزبٔخ االٔؾٕبء -ب أْ ِمبِٚخ اٌضٕٟ ٌٍّبدح ٟ٘ لبث١ٍخ رؾًّ رٍه اٌّبدح ٌمٜٛ اٌضٕٟ . اٌّغٍطخ ثظٛسح ػّٛد٠خ ػٍٝ ِؾٛس٘ب اٌطٌٟٛ ٚأْ اإلعٙبد إٌبشئ ػٓ رغ١ٍؾ ؽًّ اٌضٕٟ ٘ٛ ارؾبد ٌضالصخ أٔٛاع رىْٛ , ِٓ اإلعٙبداد اٌزٟ رؾذس فٟ ِٛالغ ِخزٍفخ ٚثٕفظ اٌٛلذ -:[30]ِغؤٌٚخ ػٓ ؽذٚس ٘زا إٌٛع ِٓ اٌفشً ّٚ٘ب اإلعٙبداد 3-. اإلعٙبداد االٔؼغبؽ١خ2-. اإلعٙبداد اٌشذ٠خ1 .اٌمظ١خ test)أْ أػظُ إعٙبد فٟ ظشٚف فؾض اٌضٕٟ اٌضالصٟ إٌمطخ point three) ٓٚاٌؾبطً فٟ ِٕظف اٌّغبفخ ث١ٓ اٌّغبٔذ ٠ّى ثٛاعطخ (االٔؾٕبء-اٌؾًّ)أْ ٠ؾغت ألٞ ٔمطخ ػٍٝ ِٕؾٕٟ -: [16] [17]اٌؼاللخ 2max 2 3 bd sf  … (3) -:ؽ١ش أْ ( max) : ٗإعٙبد اٌضٕٟ ٚٚؽذار ٛ٘( 2m n ثبعىبي(pa) .) ( f) : ًّاٌؾ(n .) ( s) : اٌّغبفخ ث١ٓ اٌّغبٔذ(m .) ( b) : ػشع اٌؼ١ٕخ(m .) ( d) : عّه اٌؼ١ٕخ(m .) ( d)ٚث١ٓ اٌغّه (s)إرا وبٔذ إٌغجخ ث١ٓ اٌّغبفخ ث١ٓ اٌّغبٔذ أْ . فئْ ٕ٘بن أؾٕبء وج١ش عٛف ٠ؾظً ٌٍؼ١ٕخ (16)أوجش ِٓ أػظُ إعٙبد ػٍٝ اٌغطؼ اٌخبسعٟ ٌٍؼ١ٕخ ٠ّىٓ أْ ٠ؼطٝ ٚثظٛسح -: اٌزب١ٌخ[16] [17]رمش٠ج١خ ِٓ اٌّؼبدٌخ . االٔؾٕبء فٟ ٚعؾ اٌّغبفخ ث١ٓ اٌّغبٔذ: (d)ؽ١ش … (4)                            s d s d s d bd sfb 461 2 3 2 2max أْ ِمبِٚخ االٔضٕبء رىْٛ ِغب٠ٚخ إٌٝ اإلعٙبد اٌىٍٟ فٟ ٌؾظخ ٠ّٚىٓ ؽغبة ِمبِٚخ االٔضٕبء ثبٌزٛافك ِغ . ؽذٚس اٌىغش ٚرٌه ثزؼ٠ٛغ ل١ّخ اٌؾًّ ثّب ٠غب٠ٚٗ ٌؾظخ (4(, )3)اٌّؼبدٌز١ٓ -: اٌزب١ٌخ[16] [17] [29]ٚ٘زا ٠ؼٕٟ, ؽذٚس اٌىغش   22 3 .. bd sf sf b b  … (5) -:ؽ١ش أْ ( b) :ِمبِٚخ االٔضٕبء . ( fb) :ؽًّ اٌىغش. ( forces shear)ٚوّب ٘ٛ ِزوٛس أػالٖ فٕٙبن لٜٛ لظ١خ ػالٚح ػٍٝ لٜٛ اٌشذ ٚاالٔؼغبؽ ٚػ١ٍخ ٠ّىٓ ؽغبة إعٙبد ٌٍّٕٛرط اٌخبػغ ٌفؾض اٌضٕٟ ِٓ (stress shear) (τ)اٌمض -:[30]اٌؼاللخ ا٢ر١خ bd fb 4 3  … (6) test strength (.i.s)) اخزجبس ِمبِٚخ اٌظذِخ -:ثأٍاًال impact) رؼشف ِمبِٚخ اٌظذِخ ػٍٝ أٔٙب ِمذاس اٌطبلخ اٌّّزظخ فٟ إٌٝ ِغبؽخ (اٌّبدح اٌّشاد اخزجبس٘ب)وغش عغُ رٞ وزٍخ ِؾذدح ٚثزٌه ٠ّىٓ اٌمٛي أْ اٌّبدح , اٌّمطغ اٌؼشػٟ ٌٍؼ١ٕخ ػٕذ اٌىغش اٌزٟ رّزٍه ؽبلخ وغش ػب١ٌخ رىْٛ راد ِزبٔخ ػب١ٌخ ٚرؾغت -:[18]ِمبِٚخ اٌظذِخ ِٓ اٌؼاللخ ا٢ر١خ اٌطبلخ اٌالصِخ ٌٍىغش ـــــــــــــــــــــــــــــــــــــــــــــــــــــــــ = ( .ls)ِمبِٚخ اٌظذِخ ِغبؽخ اٌّمطغ اٌؼشػٟ ٌٍؼ١ٕخ ػٕذ اٌىغش (7) ... )ثٛؽذح (.i.s)ٚرمبط 2 . m joulk .) (instrument test hardness) اخزجبس اٌظالدح -:ثاٌلاًال ِٓ اٌخٛاص ا١ٌّىب١ٔى١خ (hardness)أْ خبط١خ اٌظالدح اٌغطؾ١خ اٌّّٙخ ٚاٌزٟ ٠ّىٓ رؼش٠فٙب ثأٔٙب ِمبِٚخ اٌّبدح ٌالؽزشاق ِٚٓ ٘زا اٌزؼش٠ف ٠زؼؼ أْ اٌظالدح ١ٌغذ داٌخ . أٚ اٌزشٖٛ اٌٍذْ ک ٌخبط١خ ِٕفشدح ٚأّٔب ٟ٘ خبط١خ رشاثؾ ثّزغ١شاد اٌّبدح (ِؼبًِ اٌّشٚٔخ ِٚمبِٚخ اٌخؼٛع ٚإصاٌخ االٔفؼبي ٚاٌزشٖٛ اٌذائُ) ٚأْ ٘زٖ اٌّؤصشاد رؼزّذ ػٍٝ دسعخ اٌؾشاسح ِٚمذاس ِٚؼذي . [19]اٌزشٖٛ اٌجأة اٌؼًٍّ. 4 :اٌّىاد اٌّسرؼٍّح 4.1 ( material matrix) اٌّبدح األعبط -أ –اٌّبدح األعبط اٌّغزؼٍّخ فٟ ٘زٖ اٌذساعخ ٟ٘ سارٕظ اٌف١ٕٛي . اٌّزٛفش ٌذٜ ششوخ راد اٌظٛاسٞ (ٔٛفٛالن)فٛسِبٌذ٠ٙب٠ذ ٔٛع أْ إٌٛفٛالن ٘ٛ ػجبسح ػٓ وزً طخش٠خ ٠زُ ؽؾٕٙب ٚخٍطٙب ِغ ( %10)ثٕغجخ (hmta)اٌّبدح اٌّظٍذح ا١ٌٙىغبِض١ٍٓ رزشأأ١ِٓ .[1] [30]ٚصٔبً (material reinforcing) ِٛاد اٌزذػ١ُ -ب ث١ٙئخ أ١ٌبف لظ١شح ثأؽٛاي (e)اعزؼٍّذ أ١ٌبف اٌضعبط ٔٛع (. 14μm-10)ج ٚراد لطش ٠مذس (8mm-6)ِؼ١ٕخ رزشاٚػ ث١ٓ أْ اٌّٛاد اٌّزشاوجخ اٌّشىٍخ ال رؾزٛٞ فمؾ اٌشارٕغبد ِٚب ٠زجؼٙب ِٓ ِٛاد اٌزغ١ٍؼ ثً أٔٙب رؾٛٞ ػٍٝ ِٛاد ِؼ١ٕخ أخشٜ راد ؽج١ؼخ 82 72، طفحح 2، اٌؼذد 5ِجٍح اٌخىاسصًِ اٌهٕذسٍح اٌّجٍذ سوال ػثذ اٌخؼش ػثاط (200 9) 76 خبطخ ٌزؾغ١ٓ طفبرٙب أالعزخذا١ِٗ أٚ ِٓ أعً رغ١ًٙ ػ١ٍّخ . رظ١ٕفٙب ٚاعزٕبدا إٌٝ رٌه رُ اعزخذاَ ػٛاًِ رؾغ١ٓ إٌٛػ١خ اٌّزّضٍخ -:ثبٌّٛاد اٌزب١ٌخ اٚوغ١ذ اٌّغٕغ١َٛ ٚ٘ٛ ِٓ اٌّٛاد اٌزٟ رغزخذَ وّؼغالد 1ٌٍزشاثؾ أٌزشبثىٟ رؼًّ ػٍٝ ص٠بدح عشػخ رفبػالد اٌزشاثؾ أٌزشبثىٟ ٚثبٌزبٌٟ رم١ًٍ صِٓ اٌزمغ١خ ٚأْ ٔغجخ ٘زٖ اٌّٛاد (. %1)اٌّؼبفخ ٟ٘ ثؾذٚد ٟٚ٘ ِٓ اٌؾٛاِغ اٌشؾ١ّخ اٌزٟ رغزؼًّ (olic) اال١١ٌٚه 2وّٛاد ِضٌمخ داخً وزٍخ اٌٍذائٓ اٌف١ٌٕٛ١خ اٌّطٛس رمَٛ ثذٚس رؾش٠ش اٌغٍؼخ اٌّظٕؼخ ِٓ ؽفش اٌمٛاٌت ٌزأ١ِٓ ػذَ اٌزظبلٙب (. %3-1)ٚاْ ٔغجخ ٘زٖ اٌّٛاد ٟ٘ ثؾذٚد عزشاد اٌشطبص ٟٚ٘ ِٛاد ِشززخ رؼًّ ػٍٝ أزشبس 3فٟ اٌّؾٍٛي (أٚوغ١ذ اٌّغٕغ١َٛ)ِؼغالد اٌزشاثؾ أٌزشبثىٟ ٚأْ ٔغجخ ٘زٖ اٌّٛاد اٌّؼبفخ ٟ٘ , اٌشارٕغٟ ٚرّٕغ رشعجٗ (. %0.7)ثؾذٚد ثٌٟٛ خالد اٌفب١ٕ٠ً ٚ٘ٛ ِٓ اٌّٛاد اٌزٟ رؼًّ ػٍـٝ عؼً 4اٌٍذائٓ اٌف١ٌٕٛ١خ اٌّطٛسح رّزبص ثبٌّشٚٔخ ِغ اٌمغبٚح ٚأْ ٔغجخ (. %5)٘زٖ اٌّٛاد اٌّؼبفخ ٟ٘ ثؾذٚد ٟٚ٘ ِٓ اٌظجغبد راد أطً (aniline) طجغخ اال١١ٍ١ٔٓ 5ػؼٛٞ رغبػذ ػٍٝ إوغبة إٌّزظ إٌٙبئٟ عّبالً ٚسٚٔمبً ٌّٚؼبٔبً وّب رؼًّ ػٍٝ إوغـبة إٌّزظ إٌٙبئـٟ اٌشارٕغٟ ػضي وٙشثبئٟ ػالٚح ػٍٝ أٔٙب رؼذ ِٓ اٌّـٛاد راد اٌّمبِٚخ اٌؾشاس٠خ ٚاٌى١ّ١بئ١خ اٌّّزبصح ٚأْ ٔغجخ ٘زٖ اٌّـٛاد اٌّؼبفخ (.%5-0.001)ٟ٘ ثؾذٚد ٚعذ٠ش ثبٌزوش رُ فٟ ٘زٖ اٌذساعخ اٌؾب١ٌخ رؾؼ١ش اٌّزشاوجبد اٌف١ٌٕٛ١خ اٌّمٛاح ثبأل١ٌبف اٌضعبع١خ اٌمظ١شح ثٕغجخ ٚص١ٔخ رمذس ـ:[30]ٚرٌه ثبالػزّبد ػٍٝ اٌّؼبدٌخ اٌزب١ٌخ (%60)ثؾٛاٌٟ %100 c f w w  … (8) . اٌىغش أٌٛصٟٔ ٌأل١ٌبف فٟ اٌّزشاوت: (ψ)ؽ١ش ـ :رؼطٝ ِٓ اٌّؼبدٌخ اٌزب١ٌخ (wc)ٚأْ wc = wf +wm … (9) وزٍخ األ١ٌبف ٚاٌّبدح األعبط ٚاٌّبدح ( wf,wm ,wc )ؽ١ش أْ . اٌّزشاوجخ ػٍٝ اٌزٛاٌٟ :(ذحؼٍش إٌّارج) -4.2 (preparation technique) رم١ٕخ رؾؼ١ش اٌّزشاوجبد .أ رُ رؾؼ١ش اٌّبدح اٌّزشاوجخ اٌّذسٚعخ ثبعزخذاَ رم١ٕخ اٌزششة (method impregnation) ٚاٌزٟ رؼذ ِٓ أُ٘ ؽشائك اٌمٌٛجخ ـ :١ٌٗ رُ إرجبع اٌخطٛاد اٌزب١ٌخٚعاٌف١ٌٕٛ١خ -phenol)٠ؾؼش ِض٠ظ اٌشارٕظ اٌف١ٌٕٛـ فٛسِبٌذ٠ٙب٠ذ اٌّطٛس 1formaldehyde modified) ٚرٌه ثئراثخ خ١ٍؾ (hmta novolak-) ٚصٔبً ِٓ اٌّبدح (%10)رٚ ٔغجخ فٟ وؾٛي اال٠ضبٔٛي ثبعزؼّبي خالؽ رٚ (hmta)اٌّظٍذح عشػخ ػب١ٌخ ثؼذ٘ب ٠زُ أػبفٗ ػٛاًِ رؾغ١ٓ إٌٛػ١خ ٚ ثشىً . رذس٠غٟ ِغ ِشاػبح اعزّشاس اٌخٍؾ رغّش األ١ٌبف فٟ اٌّض٠ظ اٌشارٕغٟ اٌف١ٌٕٟٛ اٌّطٛس ِغ 2. رشجغ وبفخ األ١ٌبف ثبٌشارٕظِٚشالجخاٌزؾش٠ه , ثؼذ اٌزأوذ ِٓ اٌغّش اٌغ١ذ ٚرشجغ األ١ٌبف ثبٌّض٠ظ اٌشارٕغ3ٟ ثٛاعطخ اٌٙٛاء اٌغبخٓ ٌذسعخ ؽشاسح اٌزغف١فرجذأ ِشؽٍخ 80 70)رزشاٚػ 0 c) , ؽ١ش رزشن اٌّبدح فٟ عٛ اٌفشْ ػٕذ ٘زٖ اٌذسعخ اٌؾشاس٠خ ٌّذح صالس عبػبد ٚثزٌه ٠زُ اٌزخٍض ِٓ وؾٛي اال٠ضبٔٛي اٌّغزخذَ فٟ اٌّض٠ظ ػٕذئز رظجؼ اٌّبدح ِٚٓ صُ وجظ إٌّبرط اٌّغزخذِخ فٟ , اٌّؾؼشح عب٘ضح ٌٍمٌٛجخ االخزجبساد ثبعزخذاَ اٌّىجظ ٔظف ا١ٌ٢خ اٌّظٕؼخ ِٓ لجً (.berge / batten feld )ششوخ ٚعذ٠ش ثبٌزوش أْ ٘زٖ إٌّبرط اٌّؾؼشح رُ إػذاد٘ب ؽغت -:ٚوّب٠ٍٟ (astm)اٌّٛاطفبد اٌم١بع١خ أػذد ؽغت (f.s) ػ١ٕبد اخزجبس االٔؾٕبء ِٚزبٔخ اٌضٕٟ 1ػٍّبً ثبْ ػذد (/ d790 – astm ansi)اٌّٛطفبد ؽ١ش ٠ؼذ فؾض االٔؾٕبء ِٓ (3)ج ػ١ٕبد االخزجبس رمذس . اٌفؾٛطبد اٌغ١ش ارالف١خ ( iso-179) ػ١ٕبد اخزجبس اٌظذِخ أػذد ؽغت اٌّٛاطفبد 2(. 3)ج ػٍّبً ثبْ ػذد ػ١ٕبد االخزجبس رمذس أػذد ؽغت اٌّٛاطفبد (shore-d) ػ١ٕبد اخزجبس اٌظالدح 3(astm-d2240) ػٍّبً ثبْ ػذد ػ١ٕبد االخزجبس رمذس (.3)ـج (irradiation samples) رشؼ١غ اٌؼ١ٕبد -ب فٟ دسعخ ؽشاسح اٌغشفخ گبّب رُ رؼش٠غ اٌؼ١ٕبد ألشؼخ co)ثبعزخذاَ ِظذس 60 ( 1.33)اٌزٞ ٠جؼش فٛرٛٔبد ثطبلخ ( ٚاٌزٟ ٠ّىٓ اػزجبس ِؼذي ؽبلزٙب , ١ِىب اٌىزشْٚ فٌٛذ (1.17)ٚ ١ِىب اٌىزشْٚ فٌٛذ ٚثأٚلبد ص١ِٕخ ِخزٍفخ ٌٍؾظٛي ػٍٝ (1.25) kgy(208, 312,728 .): اٌغشػبد اإلشؼبػ١خ اٌّطٍٛثخ ٟٚ٘ (:instruments) األجهضج اٌّسرخذِح 4.3 (: bending) عٙبص اخزجبس االٔؾٕبء 1ٌغشع ؽغبة ِؼبًِ اٌّشٚٔخ رُ اعزخذاَ عٙبص االٔؾٕبء األٌّبٟٔ إٌّشأ ٚف١ٗ ٠زُ رضج١ذ (phywe)اٌّظٕغ ِٓ لجً ششوخ ثظٛسح (masses)اٌؼ١ٕخ ِٓ ؽشف١ٙب ػٍٝ ِشرىض٠ٓ ٚرؼٍك اٌىزً رذس٠غ١خ ػٍٝ اٌؾبًِ اٌّضجذ ػٕذ ِٕزظف اٌؼ١ٕخ ِّب ٠غجت أؾٕبئٙب رذس٠غ١بً ِٚٓ خالي ِؤشش ِم١بط االٔؾشاف ٠ّىٓ لشاءح اٌؾبطً ٌٍؼ١ٕخ راد األثؼبد (deflection)ِمذاس االٔؾشاف .اٌّؼٍِٛخ -(:strength flexural) عٙبص ل١بط ِزبٔخ اٌضٕٟ 2رُ أعشاء االخزجبس اٌضالصٟ إٌمبؽ ثبعزخذاَ اٌّىجظ ٚرٌه (no.36110 marris bold ley)ا١ٌٙذس١ٌٚىٟ ِٓ ٔٛع ثزغ١ٍؾ اٌؾًّ رذس٠غ١بً ثبٌشأط اٌّذثت ػٕذ ِٕزظف اٌؼ١ٕخ اٌّضجزخ ِٓ ؽشف١ٙب ػٍٝ ِشرىض٠ٓ ٠ٚغزّش رغ١ٍؾ اٌؾًّ ؽزٝ ٠ؾظً .اٌىغش أٚ اٌفشً ٌٍؼ١ٕخ -: عٙبص اخزجبس اٌظذِخ3 instrument)ٌمذ رُ اعزخذاَ عٙبص اٌظذِخ ِٓ ٔٛع عبسثٟ test impact charpy) ٌٍٝغشع أعشاء اخزجبس اٌظذِخ ػ . اٌؼ١ٕبد اٌّؾؼشح 82 72، طفحح 2، اٌؼذد 5ِجٍح اٌخىاسصًِ اٌهٕذسٍح اٌّجٍذ سوال ػثذ اٌخؼش ػثاط (200 9) 77 -(:hardness) عٙبص اخزجبس اٌظالدح 4ٔٛع (hardness durometer)ٌمذ رُ اعزخذاَ عٙبص (shore-d) اال٠طبٌٟ إٌّشأ ٌم١بط اٌظالدح اٌغطؾ١خ . إٌرائج وإٌّالشح. 5 ٚفمبً ٌّب ٚسد عبثمبً سعّذ إٌزبئظ اٌؼ١ٍّخ ثشىً ِٕؾ١ٕبد أْ االٔؾشاف (2)ؽ١ش ٠الؽع ِٓ اٌشىً ( االٔؾٕبء–اٌؾًّ ) (deflection) ٌٗ فؼٕذ صٚاي , ٠زٕبعت ؽشد٠بً ِغ اٌؾًّ اٌّؾذس رأص١ش اٌؾًّ اٌّغٍؾ رغزشعغ اٌّبدح ؽبٌزٙب األٌٚٝ أٞ ػّٓ ؽذ اٌزشٖٛ اٌّشْ ٠زٕبعت االٔفؼبي ؽشد٠بً ِغ اإلعٙبد ٠ٚغزٕزظ ِٓ رٌه ٚأْ إٌغجخ ث١ٓ ( low hook’s)أْ اٌّبدح رخؼغ ٌمبْٔٛ ٘ٛن (deflection/mass) ًِمذاس صبثذ ٠ّٚضً ٕ٘ب ا١ٌّ(slope ) . [29]اٌّؾغٛة ِٓ اٌشىً اٌغبثك اٌزوش ٌىػح اٌؼاللح تٍٓ اٌىرٍح واالٔحشاف ٌٍّٕىرج اٌّحؼش ػٕذ -2-شىً .جشع إشؼاػٍح ِخرٍفح ٠ج١ٕبْ ؽظٛي ص٠بدح وج١شح فٟ ل١ُ (1)ٚ اٌغذٚي (3)ٚاٌشىً ِؼبًِ ِشٚٔخ اٌضٕٟ ٌٍّٕبرط اٌّؾؼشح اٌّشؼؼخ ثغشع إشؼبػ١خ ٚ٘زا ٠ؼٕٟ أْ االٔؾشاف لذ , kgy( 208) ٚ(312)ج رمذس أخفؼذ ل١ّزٗ فٟ اٌّبدح اٌّزشاوجخ ِمبسٔخ ثبٌّٕبرط اٌغ١ش اٌّشؼؼخ ٠ٚؼٛد ٘زا االٔخفبع فٟ االٔؾشاف (2)ٚ وّب ٘ٛ ِج١ٓ ثبٌغذٚي اٌؾبطً ػٕذ (اٌزشاثؾ اٌّغزؼشع)إٌٝ ػ١ٍّبد اٌزشبثه اٌزشاثطٟ ٘زٖ اٌغشع اإلشؼبػ١خ ٚاٌزٟ صادد ِٓ طالدح ٘زٖ اٌّبدح ٚ٘زا ٠ؼٕٟ أْ ِؼبًِ اٌّشٚٔخ ٠زغ١ش ثزغ١ش , اٌّزشاوجخ اٌّؾؼشح دسعخ اٌزشبثه اٌزشاثطٟ فجض٠بدح دسعخ اٌزشبثه اٌزشاثطٟ ٠خزفٟ [20]ِذٜ االٔغ١بث١خ اٌّشٔخ ٚرظجؼ اٌّبدح طٍذح ٚلبث١ٍخ ٌٍىغــش [21]. ؽظٛي ٔمظبْ فٟ (3)ِٚٓ عٙخ أخشٜ أ٠ؼبً ٠ظٙش اٌشىً kgy(728 )ج ل١ُ ِؼبًِ اٌّشٚٔخ ػٕذ عشع إشؼبػ١خ رمذس ٠ٚؼضٜ ٘زا االٔخفبع إٌٝ رغٍت رفبػالد اٌزٙذ٠ُ (degradation) ٚاٌزٟ رض٠ذ ِٓ اؽزّب١ٌخ ٔشٛء اٌزشممبد أٌّغٙش٠ٗ اٌزٟ رغبػذ ػٍٝ ص٠بدح ٘شبشخ اٌؼ١ٕبد ٚثبٌزبٌٟ ٔمظبْ .[21] [22]ِؼبًِ اٌّشٚٔخ گاّا اٌرؼشع ألشؼح (dose)ٌىػح ذأثٍش اخرالف جشػح -3-شىً .فً لٍُ ِؼاًِ اٌّشؤح ٌٍّٕىرج اٌّحؼش 1 ويجذ . ٌىػح لٍُ ِؼاًِ ٌىٔه ٌٍّٕىرج اٌّحؼش وػٕذ جشع إشؼاػٍح ِخرٍفح e (gpa) dose (kgy) 208 312 728 8.265 9.263 4.9615 2 جذوي لثً اٌرشؼٍغ (c0220) ٌثٍٓ خىاص اٌّادج اٌّرشاوثه اٌّذػّح تأٌٍاف اٌضجاج اٌمظٍشج ػٕذ دسجح [21] 0 novolak + g.f. (short) modulus of elasticity gpa flexural strength mpa flexural stress mpa impact strength kj/m 2 shore-d no. 2.26 109.7 3.43 28.727 62.57 رجؼبً ٌزغ١ش (.f.s)رغ١ش ِزبٔخ اٌضٕٟ ( 3 )ٚاٌغذٚي (4)٠ج١ٓ اٌشىً فمذ ٚعذ أْ أصش رفبػالد اٌزشبثه , گبّبظشٚف اٌزشؼ١غ ثأشؼخ kgy( 208 )اٌزشاثطٟ فٟ إٌّبرط اٌّؾؼشح ػٕذ عشع إشؼبػ١خ ٚرٌه ِٓ خالي اٌض٠بدح اٌؾبطٍخ فٟ ل١ُ اإلعٙبد (312)ٚ 82 72، طفحح 2، اٌؼذد 5ِجٍح اٌخىاسصًِ اٌهٕذسٍح اٌّجٍذ سوال ػثذ اٌخؼش ػثاط (200 9) 78 ِمبسٔخ ِغ إٌّٛرط اٌغ١ش kgy(312)ٚثبألخض ػٕذ اٌغشػخ ثؼذ٘ب ٠الؽع اصش رفبػالد اٌزٙذَ فٟ ٘زٖ اٌّبدح اٌّزشاوجخ , اٌّشؼغ اٌّؾؼشح ٚرٌه ثبالٔخفبع اٌؾبطً فٟ ل١ُ ِزبٔخ االٔؾٕبء ػٕذ kgy(728.)ج عشػخ رؼشع رمذس ٌىػح ذأثٍش ذغٍش اٌجشع اإلشؼاػٍح فً اخرالف لٍُ ِرأح -4-شىً .االٔحٕاء ٌٍّٕىرج اٌّحؼش 3 جذوي ٌٍّٕىرج اٌّحؼش وػٕذ جشع إشؼاػٍح (.f. s) ٌىػح لٍُ ِرأح اٌلًٕ .ِخرٍفح f. s. (mpa) dose (kgy) 208 312 728 157.232 182.389 62.983 وّب رُ اعزخذاَ اٌّغٙش اٌؼٛئٟ فٟ دساعخ ؽج١ؼخ عطؼ اٌىغش اٌؾبطً ٌٍّٕٛرط اٌّؾؼش ٚاٌٛالغ رؾذ اخزجبس ِزبٔخ 2)االٔؾٕبء ٚػٕذ دسعخ 0 c أْ (5)فمذ ٌٛؽع ِٓ اٌشىً (20 ج عطؼ اٌىغش ٌٍؼ١ٕبد اٌّشؼؼخ ثغشػخ إشؼبػ١خ رمذس kgy(728) اٌششٚؿ فٟ أ١ٌبف اٌضعبط ٚؽظٛي ٠ز١ّض ثبٔزشبس ٌجؼؼٙب ِظؾٛثخ ثزٙشُ اٌّبدح األعبط (tear)ؽبٌخ اٌزّضق ػالٚح ػٍٝ رٌه رُ . اٌشارٕغ١خ اٌّزّضٍخ ٕ٘ب ثشارٕظ إٌٛفٛالن ِالؽظخ ِٓ خالي اٌظٛس اٌّغٙش٠خ رؾطُ اٌغطٛػ اٌج١ٕ١خ ِغ رجؼضش ٚرشظٟ اٌشارٕظ ِٓ (١ٌف– األعبط )اٌفبطٍخ ث١ٓ اٌّبدح ػٍٝ أعطؼ ثؼغ األ١ٌبف ِظؾٛثخ ثبخزفبئٗ فٟ ِٕبؽك أخشٜ ٌزجذٚ ٘زٖ األ١ٌبف راد عطٛػ ٔظ١فخ ٟٚ٘ ِؤشش ٌؼؼف لٛح اٌزالطك ِبث١ٓ اٌّبدح األعبط ٚاأل١ٌبف ِغ اعزّشاس ص٠بدح .اٌغشػخ اإلشؼبػ١خ أْ ِمبِٚخ اٌمض ( 4 )ٚاٌغذٚي (6)وّب ٠زؼؼ ِٓ اٌشىً ٌٍطجمبد اٌذاخ١ٍخ رغٍه عٍٛوبً ِّبصالً ٌّزبٔخ االٔؾٕبء ِّب ٠ؤوذ ؽبٌخ .[29]اٌزٕبعت ث١ّٕٙب رغ١ش ( 5 )ٚاٌغذٚي (7)وّب ث١ٕذ إٌزبئظ اٌّزّضٍخ ثبٌشىً فمذ , گبّبرجؼبً ٌغشػخ اٌزؼشع ألشؼخ (.i.s)ِمبِٚخ اٌظذِخ أظٙشد اٌّبدح اٌّزشاوجخ اٌشارٕغ١خ ػٕذ اٌغشع اٌؼب١ٌخ طفخ .اٌٙشبشخ ٌٍّٕىرج اٌّحؼش (τ)ٌىػح اٌؼاللح تٍٓ لٍُ إجهاد اٌمض -6-شىً .واٌجشع اإلشؼاػٍح 4 جذوي ٌٍّٕىرج اٌّحؼش وػٕذ جشع إشؼاػٍح (τ) ٌىػح لٍُ إجهاد اٌمض .ِخرٍفح τ (mpa) dose (kgy) 208 312 728 3.93 4.559 1.572 ثظٛسح ػبِخ ٠ؾذس اٌفشً فٟ اٌّبدح اٌشارٕغ١خ غ١ش اٌّذػّخ اٌخبػؼخ ٌفؾض اٌظذِخ ثزؾط١ُ االسرجبؽـبد أٚ اٌمٜٛ فٟ اٌج١ٌّٛش ٚرٌه ثّٕٛ اٌششٚؿ األ١ٌٚخ اٌّؾذصخ ثفؼً اعٙبداد اٌظذِخ ٚاٌٛالغ أْ ٘زٖ اٌششٚؿ اٌّزٌٛذح رّٕٛ ٚرزىبصش ثشىً وج١ش ٚعش٠غ ثبرغبٖ اٌغطـٛػ اٌج١ٕخ اٌفبطٍخ ث١ٓ اٌغالعً اٌج١ٌّٛش٠خ ألْ van der waal)اٌمٜٛ ث١ٓ ٘زٖ اٌغالعً ِزّضٍخ ثمٜٛ فبٔذسفبي أِب اٌششٚؿ اٌّّزذح , اٌزٟ رزطٍت ؽبلخ ل١ٍٍخ ٌٍزغٍت ػ١ٍٙـب (– ثبالرغبٖ اٌؼّٛدٞ ػٍٝ ارغبٖ اٌغالعً اٌج١ٌّٛش٠خ فغـٛف رؼّـً ػٍٝ رؾط١ُ رٍه اٌغالعً خالي ػ١ٍّخ االٔزشبس (propagation) ٍٝأْ ٘زا األِش ٠زطٍت ؽبلخ اوجش ٌٍزغٍت ػ , رٍه اٌمٜٛ اٌّغئٌٛخ ػٓ سثؾ اٌٛؽذاد اٌزشو١ج١خ ٚاٌّزّضٍخ ثبألٚاطش اٌزغب١ّ٘خ ٚػٕذ رغ١ٍؼ اٌّبدح اٌج١ٌّٛش٠خ ثبأل١ٌبف ٔالؽع فمجً ؽذٚس اٌفشً . [29]أْ اٌطبلخ اٌالصِخ ٌىغش اٌج١ٌّٛش رضداد فٟ اٌّبدح اٌّزشاوجخ رّش اٌّبدح ثّشؽٍز١ٓ األٌٚٝ ٟ٘ وغش اٌّبدح ٚاٌضب١ٔخ ٟ٘ اٌفشً اٌؾبطً فٟ األ١ٌبف ٚ٘ٛ (matrix)األعـبط األ١ٌبف أٚ رؼبٟٔ (tear)ٔٛػبْ فئِب أْ رزّضق ٚفٟ اٌّشؽٍخ اٌضب١ٔخ ٠ىْٛ , ِٓ اٌّبدح األعبط (pullout)أغالخبً 82 72، طفحح 2، اٌؼذد 5ِجٍح اٌخىاسصًِ اٌهٕذسٍح اٌّجٍذ سوال ػثذ اٌخؼش ػثاط (200 9) 79 ِمذاس اٌطبلخ اٌّظشٚفخ ٌىغش اٌؼ١ٕبد اوجـش ِٓ اٌّشؽٍخ األٌٚٝ .[30]فٟ ثؾضّٙب (gwilym, e.owen)ٚ٘زا ِب ٚطفٗ واٌىالغ ذحد kgy( 728)ٌسطح اٌىسش اٌحاطً ٌٍّٕىرج اٌّرشاوة اٌّرؼشع ٌجشػه ِمذساها (270x)ٌىػح طىسج ِجهشٌح تمىج ذىثٍش -5-شىً . ذأثٍش اخرثاس ِرأح االٔحٕاء -(a) ٌّلً أرشاس اٌششوخ فً وً ِٓ اٌّادج األساط واألٌٍاف ِغ ّٔى اٌفشاغاخ (voids) تاٌرظذع اٌمظً ووزٌه تششوخ اٌطثماخ اٌذاخٍٍح(cracking laminar inter .) -(b)ٌّلً ذثؼلش وذشظً اٌّادج األساط ِٓ ػٍى سطح اٌٍٍف . -(c) ٌَّلً أسحاب األٌٍاف تشىً حض (bundies) ِظحىتح ترشظً اٌّادج األساط ِغ تشوص ِٕاؽك ِرحطّح فً تؼغ األٌٍاف . -(d)ٌَثٍٓ أْ اٌرذػٍُ اٌّادج األساط تاألٌٍاف ٌؤدي إٌى ذغٍش ِٕطمح اٌىسش تظهىس سطحاًال خشٕاًال الٔسحاب األٌٍاف تشىً حض . 82 72، طفحح 2، اٌؼذد 5ِجٍح اٌخىاسصًِ اٌهٕذسٍح اٌّجٍذ سوال ػثذ اٌخؼش ػثاط (200 9) 80 -(e) ٌّلً أٌٍاف راخ أسطح ٔظٍفح (clean single fiber surfaces) خاٌٍح ِٓ اٌّادج األساط وهً ِؤشش ٌؼؼف لىج اٌرالطك ِاتٍٓ اٌّادج . األساط واألٌٍاف ػٕذ اٌجشع اإلشؼاػٍح اٌؼاٌٍح -(f)ٌّلً ذّضق (tear) األٌٍاف وأسحاتها خاسجاًال ِغ تماٌا ِٓ اٌّادج األساط(matrix) اٌٍّرظمح ػٍى سطحه . -(g)ٌّلً أسحاب األٌٍاف خاسجاًال تأسطح ٔظٍفح خاٌٍح ِٓ وجىد اٌّادج األساط ػٍٍها . -(i) ذهشُ اٌّادج األساط (matrix) ِخٍفح أٌٍاف راخ أسطح ٔظٍفح وهً ِؤشش ٌؼؼف ِماوِح اٌسطح اٌثًٍٕ تٍٓ اٌٍٍف واٌّادج األساط. ٌىػح اٌؼاللح تٍٓ ِماوِح اٌظذِح ٌٍّٕىرج اٌّحؼش -7-شىً .واٌجشع اإلشؼاػٍح ٌٍّٕىرج اٌّحؼش 5 جذوي ٌىػح لٍُ ِماوِح اٌىسش ٌٍّٕىرج اٌّحؼش وػٕذ جشع إشؼاػٍح .ِخرٍفح impact strength (i. s.) (kj/m 2 ) dose (kgy) 208 312 728 45.07 38.7 22.264 أْ رذػ١ُ ِبدح سارٕظ إٌٛفٛالن ثأ١ٌبف اٌضعبط ٠ض٠ذ ِٓ اٌّمبِٚخ اإلشؼبػ١خ ٚثبٌزبٌٟ ص٠بدح ِمبِٚخ اٌظذِخ ؽ١ش أْ ل١ُ (i.s.) ج ٌٍّبدح اٌّزشاوجخ غ١ش اٌّشؼؼخ رمذسj/m 2 فٟ (28.727 ) ؽ١ٓ ل١ّزٙب ٌٍشارٕظ اٌّذػُ ثبأل١ٌبف ثؼذ أْ رؼشع ٌغشػخ kgy(208) ٟ٘j/mج إشؼبػ١خ رمذس 2 ( 45.0 7 .) ٌىػح ذأثٍش اخرالف اٌجشع اإلشؼاػٍح فً لٍُ اٌظالدج -8شىً .ٌٍّادج اٌّحؼشج اٌزشبثٗ اٌىج١ش فٟ اٌغٍٛن ( 6 )ٚاٌغذٚي (8)وّب ٠ش١ش اٌشىً اٌزٞ رظٙشٖ ل١ُ اٌظالدح اٌغطؾ١خ ٌٍّبدح اٌّزشاوجخ اٌّؾؼشح ص٠بدح أٚ ٔمظبْ ِغ ص٠بدح عشع اإلشؼبع فمذ أظٙشد إٌزبئظ ا١ٌّىب١ٔى١خ أْ اإلشؼبع أدٜ رم١ًٍ إٌٝ ٌذأخ اٌؼ١ٕبد ٚص٠بدح ٘شبشزٙب ِّب ٠ؤدٞ إٌٝ أػؼبف ِمِٛزٙب ٌٍزخذػ ٚاٌغشص kgy(728.)ج ٚخظٛطبً ػٕذ عشػخ رؼشع إشؼبػ١خ رمذس 6 جذوي . ٌىػح لٍُ اٌظالدج ٌّٕىرج اٌّحؼش وػٕذ جشع إشؼاػٍح ِخرٍفح طالدج (shore – d) no. dose (kgy) 208 312 728 82.1 71.3 67.1 االسرٕراج . 6 ٘زٖ اٌذساعخ أظٙشد أْ ػ١ٍّخ رذػ١ُ سارٕظ إٌٛفٛالن ثأ١ٌبف ٚإْ اٌفؾٛطبد . اٌضعبط ٠ؤدٞ إٌٝ رؾغ١ٓ ِمبِٚزٗ اإلشؼبػ١خ ِمبِٚخ اٌمض , ِزبٔخ االٔؾٕبء, االٔؾٕبء)ج ا١ٌّىب١ٔى١خ اٌّزّضٍخ أظٙشد ٔٛػبً ِٓ (اٌظالدح اٌغطؾ١خ, ِمبِٚخ اٌظذِخ, اٌذاخ١ٍخ . ِغ ص٠بدح عشع اإلشؼبع (ص٠بدح أٚ ٔمظبٔبً )اٌؼشٛائ١خ أدد إٌٝ رم١ًٍ ٌذأخ اٌّبدح گبّب وّب أظٙشد إٌزبئظ أْ أشؼخ اٌّؾؼشح ٚص٠بدح ٘شبشزٙب ٚخظٛطبً ػٕذ عشػخ رؼشع kgy(728 .)ج إشؼبػ١خ رمذس kgy(728 ) ج وّب أْ اٌغشع اإلشؼبػ١خ اٌؼب١ٌخ اٌزٟ رمذس رؤدٞ إٌٝ إػؼبف ِٕطمخ اٌغطؼ اٌج١ٕٟ اٌفبطٍخ ث١ٓ اٌّبدح . األعبط ٚاأل١ٌبف ٚثبٌزبٌٟ إػؼبف لٛح اٌزالطك ِبث١ّٕٙب اٌّظادس. 7 [1] a. knop and l. pilato, "phenolic resins chemistry", springer verlag, berlin meidelberg new york tokyo, (1985). 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[24] gwilym and e.-owen; "polymer engineering sci", vol. 8, p. 467, (1981). ؽشق اعزؼّبي اٌؼٕبطش اٌّشؼخ فٟ )اؽّذ خؼش ػغ١ٕخ, [25] , ِطجؼخ (اٌؼٍَٛ اٌج١ٌٛٛع١خ ٚاٌج١ئ١خ ٚاٌف١ض٠بئ١خ (1989).اٌّٛطً, اٌٛلب٠خ ِٓ اإلشؼبػبد " , اٌذوزٛس ثٙبء اٌذ٠ٓ ِؼشٚف [26] ِطجؼخ ثبثً ـ , ِٕظّخ اٌطبلخ اٌزس٠خ اٌؼشال١خ, "اٌّؤ٠ٕخ ), ثغذاد 1989.) , مطبعة "مقدمة فً الفٌزٌاء الصحٌة"خالد عبٌد األحمد, [27] (1993).جامعة الموصل على بعض گبّبدراسة تأثٌر "عباس جواد عبد السعدي, [28] الخواص الفٌزٌائٌة لبعض العوازل الكهربائً , رسالة"البولٌمرٌة دكتوراه كلٌة التربٌة أبن الهٌثم .(1997) دراسة التأثٌر الحراري على "روال عبد الخضر عباس, [29] –, مجلة النهرٌن "الخواص المٌكانٌكٌة لمتراكب هجٌنً العدد األول, الصفحة العلوم المجلد العاشر .(2007)(11-23) دراسة الخصائص الحرارٌة "روال عبد الخضر عباس, [30] , رسالة "والمٌكانٌكٌة لمادة النوفوالك ومتراكباتها الجامعة التكنولوجٌة ماجستٌر, قسمالعلوم التطبٌقٌة .(2001) 22 rula abdul khider abbas al-khwarizmi engineering journal, vol. 5, no. 2, pp 72 -82 (2009) 82 study the effect different radioactive dose on mechanical properties of composite material from novolak resin exposure to high – energy radiation rula abdul khider abbas*, muzher ali sahib** and muhammad slab hamza*** * applied sciences / technology university ** electromechanical engineering department / technology university *** materials engineering / technology university abstract the research involves using phenol – formaldehyde (novolak) resin as matrix for making composite material, while glass fiber type (e) was used as reinforcing materials. the specimen of the composite material is reinforced with (60%) ratio of glass fiber. the impregnation method is used in test sample preparation, using molding by pressure presses. all samples were exposure to (co60) gamma rays of an average energy (2.5)mev. the total doses were (208, 312 and 728) kgy. the mechanical tests (bending, bending strength, shear force, impact strength and surface indentation) were performed on un irradiated and irradiate samples. all of the mechanical properties were improved with an increase in radioactive dose of up to (312) kgy to be decreased afterwards. the topography of some physically tested specimens was studied using optical microscopy. microsoft word f9e h3he1 h,e9) h9e13647 this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 17, no. 4, december, (2021) p. p. 3647 analysis and evaluation of a quasi-passive lower limb exoskeleton for gait rehabilitation niaam kh. al-hayali* somer m. nacy** jumaa s. chiad*** o. hussein**** *,**department of biomedical engineering/ alkhwarizmi college of engineering/ university of baghdad/baghdad iraq *** department of mechanical engineering/ college of engineering/ al-nahrain university/ baghdad – iraq **** department of automated manufacturing engineering/ alkhwarizmi college of engineering/ university of baghdad/ baghdad – iraq *email: neaam@kecbu.uobaghdad.edu.iq **email: somernacy@googlemail.com ***email: jumaachiad@gmail.com ****email: omar.hussein@kecbu.uobaghdad.edu.iq (received 4 august 2021; accepted 20 december 2021) 7https://doi.org/10.22153/kej.2021.12.00 abstract lower extremity exoskeletons can assist with performing particular functions such as gait assistance, and physical therapy support for subjects who have lost the ability to walk. this paper presents the analysis and evaluation of lightweight and adjustable two degrees of freedom, quasi-passive lower limb device to improve gait rehabilitation. the exoskeleton consists of a high torque dc motor mounted on a metal plate above the hip joint, and a link that transmits assistance torque from the motor to the thigh. the knee joint is passively actuated by spring installed parallel with the joint. the action of the passive component (spring) is combined with mechanical output of the motor to provide a good control on the designed exoskeleton while walking. the results show that muscles' efforts on both the front and the back sides of the user's leg were decreased when walking using the exoskeleton with the motor and spring. keywords: exoskeleton, lower limb, gait cycle, quasi-passive, rehabilitation. 1. introduction assistive exoskeletons for healthcare like rehabilitation and gait assistance has been widely developed [1][2][3]. lower limb exoskeletons are defined as wearable devices that are worn by a human and work in concert with the wearer’s movements [4][5]. lower limb exoskeletons can be used to aid the rehabilitation training by providing functional motion assistance for people with neurological and age related disorders [3][6][7][8]. during manual rehabilitation training, the training time is limited to the therapist. with this limitation of time, the gait style of the patient is not reproducible and thus the whole therapy is not optimal [9][10]. rehabilitation exoskeletons allow normal and symmetrical walking style with raising the period and intensity of the practice sessions [11][12]. a number of lower limb exoskeletons and their features for rehabilitation have been presented by researchers. in 2003, hiroaki kawamoto et al developed hal which is integrated with the human and assists proper power for lower extremity of patients with a gait disorder. the exoskeleton is actuated by electrical motor and niaam kh. al-hayali al-khwarizmi engineering journal, vol. 17, no. 4, p.p. 3647 (2021) 37 controlled based on emg signals [13][14]. in 2004, an over ground lower limb exoskeleton bleex from university of california-berkeley was designed for people's rehabilitation and assistance. the exoskeleton is actuated by three hydraulic cylinders for each leg, and its control based on feet pressure signals [5][15][16]. in 2006, expos was developed by sogang university for patients and elderly people. expos integrated an automatic platform as caster walker to retain the balance during walking. the device is pneumatically actuated, and its control by the neural network theory [2][9]. the rex exoskeleton by rex bionics was developed in 2007 for subjects with spinal cord injury (sci) [17] which is able to selfbalance during motion. rex is actuated by an electrical motor, and it is the only completely self-supporting (i.e. handfree), independently controlled exoskeleton available among both the commercial and research prototypes [18][19]. in 2007, alex developed by sai k. banala et al, which is a powered orthosis device used for gait training of subjects with walking disorders. the exoskeleton has linear actuators at hip and knee joints [20][21], it is also instrumented with force-field controller [22]. in 2013, ekso bionics [23] developed an exoskeleton designed for gait rehabilitation and assistance purposes, named “ekso gt exoskeleton”. this design has been developed as a powered over ground exoskeleton containing a hydraulic actuator. the assistance level presented by ekso device can be adjusted according to user's need [8]. in 2020, y. m. pirjade et al. designed and fabricated eight degrees of freedom lower extremity exoskeleton for gait training. the lower extremity hybrid exoskeleton works on a pre-defined walking gait cycle and is driven by electric actuators and mechanical springs. the exoskeleton has electric actuators at the hip and knee joints which provide assistive torque at the joints. the ankle joint of the device is passively actuated by a spring [24]. this paper aims to analyze and develop a new lower limb exoskeleton for gait rehabilitation to assist patients in their walking. since the above mentioned exoskeletons are active (powered) devices and need more sophisticated instruments to be controlled and according to the limitations of the power-to-weight ratio that appears in such exoskeletons, the presented exoskeleton is quasipassive which is lightweight and require very low power to work. 2. materials and methods the assistive exoskeleton presented in this work is proposed to serve both able-bodied and subjects with lower limb weakness by reducing their lower limb muscles effort during walking. 2.1. clinical gait cycle analysis clinical gait analysis is important, not only to build a mathematical model, but also to improve the design of exoskeletons. the amit biomechanics force plate model or6-7 was used for the measurement of the ground reaction forces (grfs) of the right lower limb of the healthy participant. amit's bioanalysis software is a completely featured biomechanics analysis to analyze the biomechanics of human gait cycle. the amti’s netforce data gathering software can be interfaced directly with the amit's bioanalysis program for analyzing and processing the data. the vertical and horizontal grfs, which are acted on the undersurface of a subject's right foot throughout the walking cycle were calculated. simultaneously, a camera was used to measure the motion tracking in order to be analyzed and evaluated by kinovea to calculate the angles of the hip and knee joints throughout a complete gait cycle. 2.2. mathematical model of human lower limb in order to choose the appropriate motor to be used in the presented design, a mathematical model for the lower extremity of the human body throughout a full and normal gait cycle was built to calculate the hip joint torque. the following mathematical analysis for human lower limb is based on measuring the kinematics of the human body parts complemented with the grfs measurement. the inertia forces were neglected in this analysis, thus the presented analysis was considered as a quasi-static analysis.. consider the right lower limb, the hip joint torque can be calculated throughout different phases of the gait cycle as illustrated below. the angle between the foot and the leg is not considered in this research, the foot is considered as a rigid body in the human model. where, m1: is the thigh mass, m2: is the shank mass, and m3: is the foot mass. the locations of these masses on the leg are approximate and not accurate. l1: is the thigh length, and l2: is the shank niaam kh. al-hayali al-khwarizmi engineering journal, vol. 17, no. 4, p.p. 3647 (2021) 38 length. fx: is the horizontal grf, fy: is the vertical grf. and t1: is the hip joint torque. 1stance phase 1st double support: throughout the 1st double support phase, the hip and knee joints are both in the condition of flexion as shown in figure 1. the hip joint so as the knee joint are both positive and mainly the hip joint angle is less than the knee joint. taking moment at hip joint (t1): t1+m1*g[(l1/2)sinθ1]+m2*g[(l2/2)sin(θ1θ2)+l1sinθ1]+m3*g[l2sin(θ1-θ2)+l1sinθ1]= fx[l2cos(θ1-θ2)+l1cosθ1]+fy[l2sin(θ1-θ2)+l1sinθ1] … (1) fig. 1. 1st double support phase. 2stance phase single limb stance: in the case of when the hip joint is in the condition of flexion and the knee joint angle is greater than the hip joint as shown in figure 2. taking moment about hip joint (t1): t1+m1*g[(l1/2)sinθ1]+m2*g[(l2/2)sin(θ1θ2)+l1sinθ1] +m3*g[l2sin(θ1-θ2)+l1sinθ1]= fx [l2cos(θ1-θ2)+l1cosθ1] +fy[l2sin(θ1θ2)+l1sinθ1] … (2) fig. 2. single limb stance with hip joint flexion. 3stance phase single limb stance: in the case of when the hip joint is in the condition of extension and the knee joint angle is greater than the hip joint as shown in figure 3. taking moment about hip joint (t1): t1=m1*g[(l1/2)sinθ1]+m2*g[(l2/2)sin(θ1+θ2)+l1s inθ1] +m3*g[l2sin(θ1+θ2)+l1sinθ1]+fx[l2cos(θ1+θ2)+l1 cosθ1]+fy[l2sin(θ1+θ2)+l1sinθ1] … (3) fig. 3. single limb stance with hip joint extension. 4stance phase 2nd double support: throughout the 2nd double support phase, the hip joint is in the condition of extension with a negative joint angle, and the knee joint is in the condition of flexion with a positive joint angle as shown in figure 4. niaam kh. al-hayali al-khwarizmi engineering journal, vol. 17, no. 4, p.p. 3647 (2021) 39 taking moment about hip joint (t1): m1*g[(l1/2)sinθ1]+m2*g[(l2/2)sin(θ1+θ2)+l1sinθ1 ]+m3*g[l2sin(θ1+θ2)+l1sinθ1]+fx [l2cos(θ1+θ2)+l1cosθ1]= fy[l2sin(θ1+θ2)+l1sinθ1]+t1 … (4) fig. 4: 2nd double support phase. 5swing phase: in the case of when the hip joint is in the condition of extension and the knee joint is in the condition of flexion as shown in figure 5: taking moment about hip joint (t1): m1*g[(l1/2)sinθ1]+m2*g[(l2/2)sin(θ1+θ2)+l1sinθ1 ] +m3*g[l2sin(θ1+θ2)+l1sinθ1] = t1 … (5) fig. 5. swing phase with hip joint extension and knee joint flexion. 6swing phase: in the case of when both joints are in the condition of flexion as shown in figure 6. taking moment about hip joint (t1): t1= -m1*g[(l1/2)sinθ1]m2*g[l1sinθ1+(l2/2)sin(θ1-θ2)] m3*g[l1sinθ1+l2sin(θ1-θ2)] … (6) fig. 6. swing phase with hip and knee joints flexion. in order to calculate the torques at lower limb hip joint, the variation of the hip and knee joint's angles, and the vertical and horizontal grfs throughout the gait cycle and its various phases were measured to be used as an input data for matlab program. results reveal that the maximum calculated value of torque for the hip joint throughout the complete gait cycle is 64.702n.m during the stance phase. 2.3. the proposed exoskeleton a two degree of freedom (dof) quasi-passive lower limb exoskeleton is designed to improve gait rehabilitation. the material design and selection tried not to increase the weight of the proposed exoskeleton and its components. in addition to its light weight, the exoskeleton is developed to be adjustable to be used by different users. all the components of the exoskeleton frame were made from strong lightweight aluminum alloy with foam padding to provide good ventilation, firm support, and keep maximum comfort while use. the elements in the exoskeleton were chosen based on an analysis of the kinetics and kinematics of the human walking. the schematic and overall mechanical structure of the proposed exoskeleton is shown in figure 7. this exoskeleton consists of a high torque dc servo motor, springs, links, belts, and cuffs. the electrical circuits of the proposed exoskeleton include the motor drive and the microcontroller. the final device weights about 2.7 kg without the power supply. niaam kh. al-hayali al-khwarizmi engineering journal, vol. 17, no. 4, p.p. 3647 (2021) 40 (a) (b) fig.7. the proposed lower limb exoskeleton components (a) the schematic diagram of proposed exoskeleton side and front view (all dimensions in cm), (b) the overall device. during the design of exoskeleton, an optimal set of dofs was chosen in order to allow for a user to walk normally and safely by the exoskeleton. the hip joint has three main axes which allow movement in three degree of freedom. all axes go through the rotational center of the hip joint. the flexion/extension of the hip means moving the thigh forward/backward, adduction/abduction of the hip means sideways movement of the leg away from the body/inward movement of the leg toward the midline of the body, and lateral/medial rotation means rotating movement towards the midline/rotating movement away from the midline [25]. for the hip joint, flexion/extension was included in the exoskeleton design while the abduction/adduction and lateral/medial rotations were blocked as shown in table 1. similarly, knee flexion/extension was included in the exoskeleton design. for the ankle joint, the joint was locked at 0o angle and motions in all planes were blocked. table 1, allowed and blocked dof of the proposed lower limb exoskeleton compared with natural human gait. as illustrated in figure 8, the exoskeleton consists of a high torque dc servo motor mounted on a metal plate above the hip joint, and a link that transmits assistance torque from the motor to the thigh. the motor pushes or pulls the lower part of the thigh and creates moments at the hip joint. these moments allow the hip to flex or extend. the high torque dc servo motor is used for robots and other fields requiring high torque control. the most important features of the high niaam kh. al-hayali al-khwarizmi engineering journal, vol. 17, no. 4, p.p. 3647 (2021) 41 torque dc servo motor and the motor driver are summarized in table 2. the microcontroller provides 14 digital input/output pins of which six can be used as pulse-width modulation (pwm) outputs, and six analog inputs; this can also be used as six digital input/output pins. it includes 5v linear regulator and a 16 mhz crystal oscillator, a usb connection, a power jack, an icsp header, and a reset button. the microcontroller can be powered by a usb cable or by an external battery. fig. 8. exoskeleton hip joint mechanism. table 2, high torque dc servomotor and motor driver specifications the flexion/extension knee dof was collocated with the human knee. the knee joint is passively actuated with a spring. the extended spring has a large stiffness value of 266.66 n/m, and it was 2cm in diameter, and 20cm in length. the knee joint mechanism is comprised of an extension spring in parallel to the leg as shown in figure 9 that is designed to operate with a tension load, so the spring stored energy during knee flexion and releases that energy to assist knee extension movements. this way, the spring is intended to store energy when the heel strikes the floor which is then released when the heel leaves the floor. the action of the passive component (spring) is combined with the mechanical output of the motor to provide a good control on the designed exoskeleton while walking. fig. 9. exoskeleton knee joint mechanism. niaam kh. al-hayali al-khwarizmi engineering journal, vol. 17, no. 4, p.p. 3647 (2021) 42 2.4 electromyographic activity the electromyography (emg) of the right thigh and leg muscles were recorded and collected using myoresearch-xp clinical edition (1.07.01) standard emg analysis protocols noraxonusa as illustrated in figure 10. the disposable, surface emg electrodes are of type noraxonusa [self-adhesive silver/silver chloride (ag/agcl) snap of dual electrodes 4mm diameter electrode, used for surface emg applications only]. the emg activity was recorded from four muscles, these are: rectus femoris, biceps femoris, tibialis anterior, and the med. gastrocnemius muscles. fig.10. noraxon emg measurements device and its accessories. 2.5 clinical evaluation the experimental tests on the sound person are implemented in order to obtain the behavior of gait cycle components, the lower extremity joints’ angles and the activity of the lower limb muscles, this information is important in building technical data based on the gait cycle analysis of a healthy person. the obtained information is used in the analysis, comparison, and improvement indication in the design and manufacturing of the lower limb exoskeleton. two subjects participated in this study, a healthy male participant with no history of neurological or muscular disease and no symptoms of orthopedic, and a subject with unilateral lower limb weakness. the participants were given a full explanation about the study, as well as a brief explanation about the function of the human lower limb muscles, and verbal instructions concerning the objectives and procedures of the research. each participant gave informed consent before participating to the research. some of the experimental tests are done in biomechanics laboratory in biomedical engineering department at the faculty of engineering in al-nahrain university, while the others were in biomedical engineering department at the faculty of al-khawarizmi college of engineering, university of baghdad. experimental trials were conducted in order to verify the assist effect of the proposed exoskeleton. the main aim of data analysis and acquisition from trials was the comparison of the measured emg activity while the subject was walking without and with the exoskeleton. the exoskeleton was adjusted to the subject’s size. after that, the subject walked two or three practice trials to make sure the exoskeleton had a comfortable fit to the body and so that the subject should become familiar with the exoskeleton and training environment. two different walking trials were recorded. after each trial the subject had a ten minute break. all trials were performed on a treadmill, as shown in figure 11, at fixed speeds; 0.8m/s for 3 minutes and 1.2m/s for 1 minute to simulate low to medium walking speed. the basic information of the participants and the different trials are summarized in tables 3 and 4 respectively. niaam kh. al-hayali al-khwarizmi engineering journal, vol. 17, no. 4, p.p. 3647 (2021) 43 (a) (b) fig.11. experimental tests on participants (a) healthy subject (b) subject with unilateral (right) lower limb weakness. table 3, participants basic information. participant condition age gender body mass (kilogram) body length (meter) healthy 22 male 63 1.7 unilateral (right) lower limb weakness 21 female 59 1.67 table 4, walking conditions for sound person. trial number waling description 1st trial walking without using the exoskeleton. 2nd trial walking using the exoskeleton. throughout all trials, the emg signals from four muscle groups on the right leg were recorded. the tested electrodes of each selected muscle are placed related to the learning picture equipped with the noraxon-usa software. signals from the emg electrodes were transmitted to the special purpose software to be recorded and analyzed. the raw emg signals were filtered using a notch filter (50hz) to minimize the effects of the alternating current. then, a band-pass filter (80-250hz) was used to remove motion artifacts. the emg signals were then rectified and the emg mean values were obtained. 3. results and discussion the results of emg activity of the right leg muscles of the healthy subject while walking on the treadmill at fixed speeds of 0.8m/s for 3 minutes and 1.2m/s for 1 minute are presented in figures 12 and 13, respectively. the figures reveal the mean emg activity of the med. gastrocnemius, tibialis anterior, biceps femoris, and rectus femoris muscles while walking without and with the exoskeleton. walking using the proposed exoskeleton has an effect on muscle (emg) activation, when compared to free walking (walking without the exoskeleton). the exoskeleton has different impact on each muscle depends on the location and tendons of these muscles. the four muscles' efforts on both the front and the back sides of the user's leg were decreased when walking using the exoskeleton. the motor supports and drives the leg through the appropriate step pattern during the gait cycle by adding power at the hip joint, while the knee flexion/extension has spring loaded which provides an extension torque and assists knee movements resulting in a strong effect on the leg muscles which contribute in knee flexion/extension when walking. the output of the four leg muscles was decreased significantly. this indicates less muscle effort is required to hold the niaam kh. al-hayali al-khwarizmi engineering journal, vol. 17, no. 4, p.p. 3647 (2021) 44 limb while walking. the most affected muscles were the med. gastrocnemius and the rectus femoris muscle which were decreased by 47.17% and 45.95%, respectively. as the contraction of the rectus femoris muscle contributes to hip flexion as well as knee extension, and contraction of the med. gastrocnemius muscle contributes to knee flexion, it is not surprising that the muscle activity is down when walking using the entire exoskeleton with the motor and spring installed. fig. 12. mean emg activities of the right leg muscles of the healthy subject during walking on treadmill at fixed speed 0.8 m/s for 3 minutes without and with the exoskeleton. fig.13: mean emg activities of the right leg muscles of the healthy subject during walking on treadmill at fixed speed 1.2 m/s for 1 minute without and with the exoskeleton. the emg activity tests are applied on the subject with unilateral lower limb weakness while walking on a treadmill at two fixed walking speeds 0.8m/s and 1.2m/s for 3 and 1 minutes, respectively. the emg signals of the muscles contributed in the motion of the leg were collected and analyzed. the mean emg signals when walking without and with the exoskeleton are shown in figure 14 and 15. the four muscles' efforts of the patient's leg were decreased when walking on a treadmill for 3 and 1 minutes at two fixed speeds 0.8m/s and 1.2m/s using the entire exoskeleton with the motor and spring installation. the motor supports the patient's leg and drives it through appropriate step pattern while walking by providing torque at the hip joint, while the knee flexion/extension was spring loaded which provides an extension torque and assists knee movements resulting in an effect on the leg muscles which are contributed in knee flexion/extension while walking. the reduction in emg signals indicates less muscle effort is required by the patient to hold the limb while walking using the exoskeleton. the most affected muscles were the rectus femoris and tibialis anterior on the front sides of the user's leg which are decreased by 20.755%, and 29.41%, when walking at 0.8m/s for 3 minutes, and 38.89%, and 28.1%, when walking at 1.2m/s for 1 minute, respectively. as contraction of the rectus femoris muscle contributes to hip flexion as well as knee extension, it is not surprising that the muscle activity is down when walking using the entire exoskeleton with motor and spring installation. providing adequate foot clearance during the swing of the limb when walking with the entire exoskeleton can be a reason for decreasing in emg signals of the tibialis anterior muscle. fig. 14. mean emg activity of the right leg muscles of the subject with lower limb weakness during walking on treadmill at fixed speed 0.8m/s for 3 minutes. niaam kh. al-hayali al-khwarizmi engineering journal, vol. 17, no. 4, p.p. 3647 (2021) 45 fig. 15. mean emg activity of the right leg muscles of the subject with lower limb weakness during walking on treadmill at fixed speed 1.2m/s for 1 minute. 4. conclusion quasi-passive lower limb exoskeletons usually employ a reduced number of actuators and require relatively a straight forward control strategy, resulting in energy efficient, lightweight, and operationally quiet lower limb devices. in this paper the analysis and development of a 2 dofs, autonomous, lightweight, and quasi-passive lower limb exoskeleton was presented to improve the human gait cycle. the linkage type selection is justified. a mathematical model of the human gait cycle was developed for calculating the torques at the hip joint. the mathematical model was based on the theoretical analysis of the human extremity limb throughout a full gait cycle consisting of both the stance and swing phases and the gait subphases, by investigating the behavior of the lower limb joints, the length and weights of the lower limb components, and the grfs. for the proposed exoskeleton, the spring in combination with the motor can support and assist the user's lower limb to walk in an appropriate 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[25] m. cardona and c. e. garcía cena, “biomechanical analysis of the lower limb: a full-body musculoskeletal model for muscle-driven simulation,” ieee access, vol. 7, pp. 92709–92723, 2019, doi: 10.1109/access.2019.2927515. ) 2021( 3647، صفحة 4العدد، 17مجلة الخوارزمي الهندسية المجلد نعم خالد حميد 47 السفلي لغرض إعادة تأهيل المشي تحليل وتقييم الهيكل الخارجي شبه السلبي المصمم للطرف نعم خالد حميد* سومر متي ناسي** جمعة سلمان جياد*** عمر حسين عوان**** *،**قسم هندسة الطب الحياتي/ كلية الهندسة الخوارزمي/ جامعة بغداد ***قسم الهندسة الميكانيكية/ كلية الهندسة / جامعة بغداد هندسة التصنيع المؤتمت/ كلية الهندسة الخوارزمي/ جامعة بغداد ****قسم neaam@kecbu.uobaghdad.edu.iq *البريد االلكتروني: somernacy@googlemail.com**البريد االلكتروني: jumaachiad@gmail.com ***البريد االلكتروني: cbu.uobaghdad.edu.iqomar.hussein@ke****البريد االلكتروني: الخالصة الطبيعي العالج ودعم المشي، على كالمساعدة معينة وظائف أداء في السفلي للطرف المصممة الخارجية الهياكل استخدام يساعد أن الممكن من الوزن، بدرجتين من الحرية وقابل للتعديل ليناسب لألشخاص الذين فقدوا القدرة على المشي. يقدم هذا البحث تحليل وتقييم لهيكل خارجي شبه سلبي، خفيف ته على لوحة أطوال ومفاصل الطرف السفلي للمستخدم من أجل تحسين إعادة تأهيل المشي. يتكون الهيكل الخارجي من محرك تيار مستمر عالي العزم تم تثبي إل بالتوازي مع مفصل الركبة معدنية أعلى مفصل الورك، ورابط معدني ينقل عزم الدوران المساعد من المحرك ى الفخذ. باإلضافة الى زنبرك تم تركيبه ارجي المصمم ليقوم بتحريك المفصل بشكل سلبي. يتم دمج عمل المكون السلبي (الزنبرك) مع اإلخراج الميكانيكي للمحرك لتوفير تحكم جيد في الهيكل الخ مامي والخلفي لساق المستخدم قد انخفض بشكل ملحوظ عند المشي باستخدام الهيكل الخارجي أثناء المشي. أظهرت النتائج أن جهد العضالت على الجانبين األ .الذي تم تصميمه للطرف السفلي al-khwarizmi!! engineering!!! journal al-khwarizmi engineering journal, vol.4 , no.1 , pp 58-!67 (2008!) ! ! impact energy of 100cr6 under low different velocities prof. dr. hussain. j. al-alkawi electromechanical eng. dept. university of technology lec. dr. khansaa d. alshamari electromechanical eng. dept university of technology (received 11 julay2006 ; accepted 24 september 2007) abstract: this study has been undertaken to postulate the mechanism of impact test at low velocities. thin-walled tubes of 100cr6 were deformed under axial compression. in the present work there are seven velocities (4.429,4.652,5.240,5.600,5.942,6.264, 6.569) m\sec were applied to show how they effect the load, change in length, also the kinetic energy. however, the comparison between the obtained results and the other studies (alexandar[3] , abramowicz[4], ayad[5]) was made the present work and ayad data show good agreement. load, change in length, kinetic energy were determined to understand the impact test. keywords: impact energy introduction: the use of thin-walled tubes collapsing plastically in axial compre-ssion is one of the most efficient means of energy absorption. these tubes are small in volume, easy to fabricate in weight, cheap, and stable during crushing. the crushing of thin tubes is a process by which the kinetic energy can be absorbed for example in vehicle cursh. the criterion upon which many energy absorbing devices are based, is that these devices undergo a large amount of plastic deformation before total collapse [1]. the active absorbing element of an energy absorption system can assume several common shapes such as tubes, honey combs, frusta, strips and rods. when impact velocity is less than 30 m/s, the impact is low speed impact. buckling under a low velocity can be considered as a quasi-static behavior. while impact velocities larger than 30 m/s cause stresses above the yield stress of the material, the impact is high speed impact. thin tubes deforms in one of the following modes [2]. (i) column or euler buckling. (ii) concertina or like axisy-mmetric buckling. (iii) diamond buckling. (iv) tearing of the tubes. (v) brittle fracture or shuttering. (vi) uniform compression. fig(1): thin tube deform,(a) diamond mode type buckling, (b) concertina mode type buckling, (c) invert tubes showmen (left) external, inside-out, inversion (right), internal , outside-in, inversion, (d) tearing failure [2]. many articles have been published on the static and dynamic crushing of circular tubes [1, 2]. the pioneer work of alexander [3] and abramowicz [4] of circular and square tubes under dynamic conditions. alexander [3] was the first to present a mathematical model of crushing phenomena for thin walled tubular specimens, calculating the mean crushing force of tubes and collapsing in the axisymmetric or concertina mode. while abramowicz and jones [4] have improved the alexander model by modifying the effective crushing distance and the effect of material strain rate under dynamic loading. in this article. three models namely alexander [3], abramowicz [4] and ayad [5], waheed s. mohammed al-khwarizmi engineering journal, vol.4 , no. 1 pp 58-67 (2008) òö were using thin-walled tubes which were made from 100cr6 steel tested under different velocities impact. literature review: abramoswicz [4] focuses on the range of dynamic load which give rise to a quasi-static crushing response. a series of axial crushing tests on steel circular cylindrical tubes loaded either statica-lly, or dynamically, is reported and compared with various theoretical predictions and empirical relations: a modified version of alexander's [3] theoretical solution for axisymmetric, or concertina, deformations, which includes a correction for the effective crushing distance, gives good agreem-ent with the mean of experimental static crushing loads. guillow and grezbieta [6] tested 6060 aluminum alloy tubes with different range of (d/t), internal diameter to thickness ratio from 10-450. it was found that the behavior of thin walled tubes can be described by the empirical formula. 32.0)(3.72 t d mp fav  -----------(1) where: fav: average crushing force. mp: plastic moment per unit length. also it was found that the ratio of fmax/fav increased substantially with an increase in the d/t ratio. huang and lu [7] presented an axisymmetric crushing behavior of metal tubes subjected to quasi-static axial loads. based on the experimental results and finite element analysis, a theoretical model is developed by introducing the concept of effective plastic hinge length which is proportional to tube thickness. seitzberger and willminger [8] investigated steel alloy of different types of cross-sections (square, hexa-gonal, octagonal) which are fully or partially filled with aluminum foam. the results of the parameter studies confirm with the experimental observa-tions for given tube/filler combinations and the foam is a major parameter in the design of the collapse models. ayad arab [5] studied the variety speed impact for thin walled cylinder made from 2024-t351 aluminum alloy. a proposed mathematical model was presented based on the experim-ental data. this model can predicted the mean load, variation of load and deformation for static and dynamic conditions by falling axial mass with different velocities impact. the effect of folding parameter (m) and size of fold (h) on mean load and deformation have been studied. experimental work a series of 12 axial crushing tests was conducted on circular tubes specimens loaded either statically or dynamically. this section presents the experimental work done using 100cr6 steel which is widly used in structures and in many industrial of automobiles. mechanical properties: table (1) illustrates the mechanical properties of the metal used while fig (2) shows the relation between the stress and strain (tensile test). chemical composition: table (2) shows the chemical compos-ition of 100cr6 in weight percentage. microstructure evaluation: a computerized optical microscopy was used to examine the microstru-cture of the sample. photo micrographs was taken for sample which was examined by optical microscopy as shown in fig (3). specimens preparation: circular sectioned steel alloy tubes formed by a deep drawing process were used. these tubes were cut to equal lengths by cutter machine. fig. (4) shows the shape and dimensions of the specimens used in this study [9]. test rig: the test rig used is described in details in reference [10]. experimental results: the results recorded are divided into two groupes static and dynamic as follows: static compressive test: a load of 2.5 ton at 1 mm/min head speed is chosen in order to compare the results with ref. [8] who used the same condition of waheed s. mohammed al-khwarizmi engineering journal, vol.4 , no. 1 pp 58-67 (2008) óí testing. the purpose of doing the test is to obtain the mode of deformation. the results are given in table (3), and table (4) gives the results at failure. the energy absorbed was calculated using the equation : (pm f ).(l f) = e -----------------------(2) where : lf : deformation at failure (mm) . pmf : mean load at failure (kn). e:energy absorbed by the specimen(j). impact test results: 12 specimens are tested at different speeds (4.429 6.569 ) by using a mass of (14.55 kg) at different heights. the results can be illustrated in table (5). 1) the velocity of the dropping mass was measured experimentally by the test rig end compared with the calculated velocity using the equation: v = gh2 where : h is the height of the dropping mass . the error of the results was about 5%. (h was taken from 1-2.2 m). and g = 9.81 m/sec². 2) the failure deformation (lf ) was measured from the specimen at failure 3) the dynamic mean load ( pm ) was calculated from the equation: (pm)dynamic = k.e/lf = mv²/2lf where: m is weight of the falling body = 14.55 kg figure (5) represents the increasing in the velocity leads to increase in the load as it is shown obviously in abramowicz test [4] which the increment in the load is a higher than in the others, while this increment in the present work, alexandar [3] and ayad [5] is small . most of the relationships seems to be horizontally linear. this is return to that the sample of abramowicz which was obtained for steel show that the relation between the load and the velocity curve extremely according to the:  206.0113.11 vpm  and its lead to give higher slope than in another's. figure (6) represents the results of l/l which was plotted as a function of v, it is seen that the relation of present work is extremely close to ayad work [5] and far from alexandar, abramowicz work. these relations have the same slops when they are linear proportionality. from figure (7), it is found that l/l varying with the kinetic energy, and give the same conclusions which were obtained by l/l and v, this is return to that the kinetic energy extremely related with velocity as : k=1/2mv² , hence the results are the same at which obtained between l/l and v. conclusions: the behavior of 100cr6 thin – walled tube under dynamic impact loading takes the followings : a\ the mp increases with increases in velocity v and takes a relation close to abramowicz and ayad models . b\ the variation of the ratio l/l against velocity v is taken the trend of ayad model while alexandar and abramowicz are far away from the present results. waheed s. mohammed al-khwarizmi engineering journal, vol.4 , no. 1 pp 58-67 (2008) óî !! fig. (1) shows the most types of deformation of thin-walled tubes. 0.03 0.08 0.13 0.18 0.230.00 0.05 0.10 0.15 0.20 0.25 10 30 50 70 90 0 20 40 60 80 100 st re ss ( m pa ) strain fig. (2): relationship between stress and strain !! waheed s. mohammed al-khwarizmi engineering journal, vol.4 , no. 1 pp 58-67 (2008) óï óî fig. (3): microstructure of the 100 cr6 with mg ( 270x ) t=1mm l =30mm 18mm fig. (4) : shape and specimen dimensions fig. (ò) : relationship between load and velocity !! waheed s. mohammed al-khwarizmi engineering journal, vol.4 , no. 1 pp 58-67 (2008) óð fig. (6) : relationship between deformation and velocity. fig. (7) : relationship between deformation and kinetic energy. !! !! !!k(j) waheed s. mohammed al-khwarizmi engineering journal, vol.4 , no. 1 pp 58-67 (2008) óñ table (1) mechanical properties of 100cr6 y (mpa) u (mpa) elong.% brinell hardness g (gpa) e (gpa) µ k 310 840 7.2 211 88.46 230 0.3 287.5 the above data is the average of three readings. table (2) chemical composition of the material used. c mn si p s cr ni mo cu fe% 1.05 0.40 0.23 0.016 0.009 1.77 0.07 0.03 0.17 96.122 * the above analyses was done by thermo arl 3460!º º oe spectrometer. table (3) static compressive test for 100cr6 load (kn) l (mm) load (kn) l (mm) load (kn) l (mm) load (kn) l (mm) 14.0 17 15 13 0.057 0.122 0.22 0.31 10 7 11 13 16 0.44 0.51 0.62 0.78 1.000 14.5 12 10 16 18 17 1.1 1.2 1.5 1.8 2.1 2.3 14 13 11 10 18 19 20 8 10 11 13 14 17 18 failure table (4) static results at failure failure e (j) l f (mm) pm f (kn) mode complete damage of specimen 252 18 14 concertina buckling table (5) dynamic results of 100cr6 under 14.55 kg spec.no v(m\s) lf (mm) pm (kn) h (m) mode of def.* 4 4.429 8 17.838 1 c 5 4.652 12.5 12.595 1.2 c 6 5.24 14.8 13.496 1.4 c 7 5.6 15.7 14.531 1.6 c 8 5.942 17.2 14.933 1.8 c 9 6.264 18.4 15.513 2 c 10 6.569 19.7 15.935 2.2 c 11 6.569 20.4 15.388 2.2 c 12 6.569 20.1 15.161 2.2 c 13 6.569 20.5 15.463 2.2 c 14 6.569 20.3 15.312 2.2 c 15 6.569 20 15.086 2.2 c waheed s. mohammed al-khwarizmi engineering journal, vol.4 , no. 1 pp 58-67 (2008) óò t ab le ( 6) s ho w s th e co m pa ri so n be tw ee n th re e re fe re nc es [3 ], [ 4] , [ 5] w ith th e cu rr en t w or k. waheed s. mohammed al-khwarizmi engineering journal, vol.4 , no. 1 pp 58-67 (2008) óó references [1] reid s.r. drew s. l. and karing j.e. “energy absorbing capacities of metal” inter. journal of mech. sci. 1983, 25, page 649-667. [2] karagiozovaa, d. and norman j.c. “inertia effects in axis-symmetrically deformed cylindrical shells under axial impact” internal report, liverpool university, uk. 2000 [3] alexander, j. m. “an approximate analysis of the collaps of thin cylindrical shells under axial loading” q. j. mech. appl. math 1960 pp (1-10). [4] abramowicz w. and jones, n. “dynamic axial crushing of circular tubes” int. j. impact 1984, page 263. [5]ayad arab, k. “variety speed impact of thin walled circular tubes” msc thesis, university of al-anbar (2005). [6] guillow, s.r. and grzebieta, r. h. “quasistatic” axial compression of thin-walled circular aluminum tubes” i. j. mech. sci. vol. 43, 2001 pp.2103-2123. [7] huang, x. and lu, g. “axisymmetric progressive crushing of circular tubes” i.j. crashworthiness vol.8. 2002 pp-87-95 [8] seitzberger, m. and willminger, s. “application of plastic collapse mechanisms for the axial crushing analysis of tubular steel structures filled with aluminum foam” int. j. crashworthiness, 2001 pp (165-176). [9] jones, n. and abramowicz, w. (1985) “static and dynamic axial curshing of circular and square tubes” proc. metal forming and impact mech. pergoman press oxford 1985. [10] al-badrany, ayad aied “energy absorption capacity of thin metallic tubes” msc. thesis, al-anbar university 2005. waheed s. mohammed al-khwarizmi engineering journal, vol.4 , no. 1 pp 58-67 (2008) óô !!! ! ž!!! ! !! !œ!! !œ!100cr6!! ž!!! ! !! ! ž! !! !! ! ! !! š!!! خنساء داود سلمان الشمري. دحسین جاسم محمد العلكاوي . د قسم الھندسة الكھرومیكانیكیة قسم الھندسة الكھرومیكانیكیة الجامعة التكنولوجیة الجامعة التكنولوجیة :الخالصة استخدمت عینات أنبوبیة قصیرة رقیقة المقطع من . مختلفة سرع منخفضةأجریت ھذه الدراسة لتخمین آلیة اختبار الصدمة عند وقد تم تشویھ العینات تحت تأثیر قوة ضغط أحادیة المحور في ھذه الدراسة تم تسلیط سبع سرع 100cr6معدن الفوالذ من نوع )4.429 ,4.652 ,5.240 ,5.600 ,5.942 ,6.264 ,6.569 m\sec (الطاقة , التغیر في الطول , القوة لبیان تأثیرھا على . الحركیة الدراسة ). alexandar[3] , abramowicz[4] , ayad[5])وبناًء على ذلك أجریت مقارنة بین الدراسة الحالیة ودراسات اخرى ة الحركیة لفھم آلیة االختبار الطاق, التغیر في أبعاد العینة, لقد تم حساب القوة الالزمة. ayad[5]الحالیة تتوافق بشكل جید مع دراسة ) .اختبار الصدمة ( المستخدم 0 . 0 3 0 . 0 8 0 . 1 3 0 . 1 8 0 . 2 3 0 . 0 0 0 . 0 5 0 . 1 0 0 . 1 5 0 . 2 0 0 . 2 5 1 0 3 0 5 0 7 0 9 0 0 2 0 4 0 6 0 8 0 1 0 0 0.030.080.130.180.230.000.050.100.150.200.25 10 30 50 70 900 20 40 60 80100 32 . 0 ) ( 3 . 72 t d mp fav = gh 2 ( ) 2 06 . 0 1 13 . 11 v p m + = m p waheed s. mohammed al-khwarizmi engineering journal, vol.4 , no. 1 pp 58-67 (2008) al-khwarizmi engineering journal al-khwarizmi engineering journal, vol.4 , no.1 , pp 5867 (2008 ) impact energy of 100cr6 under low different velocities prof. dr. hussain. j. al-alkawi electromechanical eng. dept. university of technology lec. dr. khansaa d. alshamari electromechanical eng. dept university of technology (received 11 julay2006 ; accepted 24 september 2007) abstract: this study has been undertaken to postulate the mechanism of impact test at low velocities. thin-walled tubes of 100cr6 were deformed under axial compression. in the present work there are seven velocities (4.429,4.652,5.240,5.600,5.942,6.264, 6.569) m\sec were applied to show how they effect the load, change in length, also the kinetic energy. however, the comparison between the obtained results and the other studies (alexandar[3] , abramowicz[4], ayad[5]) was made the present work and ayad data show good agreement. load, change in length, kinetic energy were determined to understand the impact test. keywords: impact energy introduction: the use of thin-walled tubes collapsing plastically in axial compre-ssion is one of the most efficient means of energy absorption. these tubes are small in volume, easy to fabricate in weight, cheap, and stable during crushing. the crushing of thin tubes is a process by which the kinetic energy can be absorbed for example in vehicle cursh. the criterion upon which many energy absorbing devices are based, is that these devices undergo a large amount of plastic deformation before total collapse [1]. the active absorbing element of an energy absorption system can assume several common shapes such as tubes, honey combs, frusta, strips and rods. when impact velocity is less than 30 m/s, the impact is low speed impact. buckling under a low velocity can be considered as a quasi-static behavior. while impact velocities larger than 30 m/s cause stresses above the yield stress of the material, the impact is high speed impact. thin tubes deforms in one of the following modes [2]. (i) column or euler buckling. (ii) concertina or like axisy-mmetric buckling. (iii) diamond buckling. (iv) tearing of the tubes. (v) brittle fracture or shuttering. (vi) uniform compression. fig(1): thin tube deform,(a) diamond mode type buckling, (b) concertina mode type buckling, (c) invert tubes showmen (left) external, inside-out, inversion (right), internal , outside-in, inversion, (d) tearing failure [2]. many articles have been published on the static and dynamic crushing of circular tubes [1, 2]. the pioneer work of alexander [3] and abramowicz [4] of circular and square tubes under dynamic conditions. alexander [3] was the first to present a mathematical model of crushing phenomena for thin walled tubular specimens, calculating the mean crushing force of tubes and collapsing in the axisymmetric or concertina mode. while abramowicz and jones [4] have improved the alexander model by modifying the effective crushing distance and the effect of material strain rate under dynamic loading. in this article. three models namely alexander [3], abramowicz [4] and ayad [5], were using thin-walled tubes which were made from 100cr6 steel tested under different velocities impact. literature review: abramoswicz [4] focuses on the range of dynamic load which give rise to a quasi-static crushing response. a series of axial crushing tests on steel circular cylindrical tubes loaded either statica-lly, or dynamically, is reported and compared with various theoretical predictions and empirical relations: a modified version of alexander's [3] theoretical solution for axisymmetric, or concertina, deformations, which includes a correction for the effective crushing distance, gives good agreem-ent with the mean of experimental static crushing loads. guillow and grezbieta [6] tested 6060 aluminum alloy tubes with different range of (d/t), internal diameter to thickness ratio from 10-450. it was found that the behavior of thin walled tubes can be described by the empirical formula. -----------(1) where: fav: average crushing force. mp: plastic moment per unit length. also it was found that the ratio of fmax/fav increased substantially with an increase in the d/t ratio. huang and lu [7] presented an axisymmetric crushing behavior of metal tubes subjected to quasi-static axial loads. based on the experimental results and finite element analysis, a theoretical model is developed by introducing the concept of effective plastic hinge length which is proportional to tube thickness. seitzberger and willminger [8] investigated steel alloy of different types of cross-sections (square, hexa-gonal, octagonal) which are fully or partially filled with aluminum foam. the results of the parameter studies confirm with the experimental observa-tions for given tube/filler combinations and the foam is a major parameter in the design of the collapse models. ayad arab [5] studied the variety speed impact for thin walled cylinder made from 2024-t351 aluminum alloy. a proposed mathematical model was presented based on the experim-ental data. this model can predicted the mean load, variation of load and deformation for static and dynamic conditions by falling axial mass with different velocities impact. the effect of folding parameter (m) and size of fold (h) on mean load and deformation have been studied. experimental work a series of 12 axial crushing tests was conducted on circular tubes specimens loaded either statically or dynamically. this section presents the experimental work done using 100cr6 steel which is widly used in structures and in many industrial of automobiles. mechanical properties: table (1) illustrates the mechanical properties of the metal used while fig (2) shows the relation between the stress and strain (tensile test). chemical composition: table (2) shows the chemical compos-ition of 100cr6 in weight percentage. microstructure evaluation: a computerized optical microscopy was used to examine the microstru-cture of the sample. photo micrographs was taken for sample which was examined by optical microscopy as shown in fig (3). specimens preparation: circular sectioned steel alloy tubes formed by a deep drawing process were used. these tubes were cut to equal lengths by cutter machine. fig. (4) shows the shape and dimensions of the specimens used in this study [9]. test rig: the test rig used is described in details in reference [10]. experimental results: the results recorded are divided into two groupes static and dynamic as follows: static compressive test: a load of 2.5 ton at 1 mm/min head speed is chosen in order to compare the results with ref. [8] who used the same condition of testing. the purpose of doing the test is to obtain the mode of deformation. the results are given in table (3), and table (4) gives the results at failure. the energy absorbed was calculated using the equation : (pm f ).((l f) = e -----------------------(2) where : (lf : deformation at failure (mm) . pmf : mean load at failure (kn). e:energy absorbed by the specimen(j). impact test results: 12 specimens are tested at different speeds (4.429 6.569 ) by using a mass of (14.55 kg) at different heights. the results can be illustrated in table (5). 1) the velocity of the dropping mass was measured experimentally by the test rig end compared with the calculated velocity using the equation: v = where : h is the height of the dropping mass . the error of the results was about 5%. (h was taken from 1-2.2 m). and g = 9.81 m/sec². 2) the failure deformation ((lf ) was measured from the specimen at failure 3) the dynamic mean load ( pm ) was calculated from the equation: (pm)dynamic = k.e/(lf = mv²/2(lf where: m is weight of the falling body = 14.55 kg figure (5) represents the increasing in the velocity leads to increase in the load as it is shown obviously in abramowicz test [4] which the increment in the load is a higher than in the others, while this increment in the present work, alexandar [3] and ayad [5] is small . most of the relationships seems to be horizontally linear. this is return to that the sample of abramowicz which was obtained for steel show that the relation between the load and the velocity curve extremely according to the: and its lead to give higher slope than in another's. figure (6) represents the results of (l/l which was plotted as a function of v, it is seen that the relation of present work is extremely close to ayad work [5] and far from alexandar, abramowicz work. these relations have the same slops when they are linear proportionality. from figure (7), it is found that (l/l varying with the kinetic energy, and give the same conclusions which were obtained by (l/l and v, this is return to that the kinetic energy extremely related with velocity as : k=1/2mv² , hence the results are the same at which obtained between (l/l and v. conclusions: the behavior of 100cr6 thin – walled tube under dynamic impact loading takes the followings : a\ the increases with increases in velocity v and takes a relation close to abramowicz and ayad models . b\ the variation of the ratio (l/l against velocity v is taken the trend of ayad model while alexandar and abramowicz are far away from the present results. 61 table (1) mechanical properties of 100cr6 (y (mpa) (u (mpa) elong.% brinell hardness g (gpa) e (gpa) µ k 310 840 7.2 211 88.46 230 0.3 287.5 the above data is the average of three readings. table (2) chemical composition of the material used. c mn si p s cr ni mo cu fe% 1.05 0.40 0.23 0.016 0.009 1.77 0.07 0.03 0.17 96.122 * the above analyses was done by thermo arl 3460ــ oe spectrometer. table (3) static compressive test for 100cr6 load (kn) (l (mm) load (kn) (l (mm) load (kn) (l (mm) load (kn) (l (mm) 14.0 17 15 13 0.057 0.122 0.22 0.31 10 7 11 13 16 0.44 0.51 0.62 0.78 1.000 14.5 12 10 16 18 17 1.1 1.2 1.5 1.8 2.1 2.3 14 13 11 10 18 19 20 8 10 11 13 14 17 18 failure table (4) static results at failure failure e (j) (l f (mm) pm f (kn) mode complete damage of specimen 252 18 14 concertina buckling table (5) dynamic results of 100cr6 under 14.55 kg spec.no v(m\s) (lf (mm) pm (kn) h (m) mode of def.* 4 4.429 8 17.838 1 c 5 4.652 12.5 12.595 1.2 c 6 5.24 14.8 13.496 1.4 c 7 5.6 15.7 14.531 1.6 c 8 5.942 17.2 14.933 1.8 c 9 6.264 18.4 15.513 2 c 10 6.569 19.7 15.935 2.2 c 11 6.569 20.4 15.388 2.2 c 12 6.569 20.1 15.161 2.2 c 13 6.569 20.5 15.463 2.2 c 14 6.569 20.3 15.312 2.2 c 15 6.569 20 15.086 2.2 c references [1] reid s.r. drew s. l. and karing j.e. “energy absorbing capacities of metal” inter. journal of mech. sci. 1983, 25, page 649-667. [2] karagiozovaa, d. and norman j.c. “inertia effects in axis-symmetrically deformed cylindrical shells under axial impact” internal report, liverpool university, uk. 2000 [3] alexander, j. m. “an approximate analysis of the collaps of thin cylindrical shells under axial loading” q. j. mech. appl. math 1960 pp (1-10). [4] abramowicz w. and jones, n. “dynamic axial crushing of circular tubes” int. j. impact 1984, page 263. [5]ayad arab, k. “variety speed impact of thin walled circular tubes” msc thesis, university of al-anbar (2005). [6] guillow, s.r. and grzebieta, r. h. “quasi-static” axial compression of thin-walled circular aluminum tubes” i. j. mech. sci. vol. 43, 2001 pp.2103-2123. [7] huang, x. and lu, g. “axisymmetric progressive crushing of circular tubes” i.j. crashworthiness vol.8. 2002 pp-87-95 [8] seitzberger, m. and willminger, s. “application of plastic collapse mechanisms for the axial crushing analysis of tubular steel structures filled with aluminum foam” int. j. crashworthiness, 2001 pp (165-176). [9] jones, n. and abramowicz, w. (1985) “static and dynamic axial curshing of circular and square tubes” proc. metal forming and impact mech. pergoman press oxford 1985. [10] al-badrany, ayad aied “energy absorption capacity of thin metallic tubes” msc. thesis, al-anbar university 2005. طاقة الصدمة لفولاذ 100cr6 تحت سرع منخفضة مختلفة د. حسين جاسم محمد العلكاوي د. خنساء داود سلمان الشمري قسم الهندسة الكهروميكانيكية قسم الهندسة الكهروميكانيكية الجامعة التكنولوجية الجامعة التكنولوجية الخلاصة: أجريت هذه الدراسة لتخمين آلية اختبار الصدمة عند سرع منخفضة مختلفة . استخدمت عينات أنبوبية قصيرة رقيقة المقطع من معدن الفولاذ من نوع 100cr6 وقد تم تشويه العينات تحت تأثير قوة ضغط أحادية المحور في هذه الدراسة تم تسليط سبع سرع (4.429 , 4.652 , 5.240 , 5.600 , 5.942 , 6.264 , 6.569 m\sec ) لبيان تأثيرها على القوة , التغير في الطول , الطاقة الحركية . وبناءً على ذلك أجريت مقارنة بين الدراسة الحالية ودراسات اخرى (alexandar[3] , abramowicz[4] , ayad[5] ). الدراسة الحالية تتوافق بشكل جيد مع دراسة ayad[5] . لقد تم حساب القوة اللازمة, التغير في أبعاد العينة, الطاقة الحركية لفهم آلية الاختبار المستخدم ( اختبار الصدمة ) . � embed pbrush ��� � fig. (1) shows the most types of deformation of thin-walled tubes. stress (mpa) � fig. (2): relationship between stress and strain strain fig. (3): microstructure of the 100 cr6 with mg ( 270x ) t=1mm l =30mm 18mm fig. (4) : shape and specimen dimensions �embed pbrush��� fig. (5) : relationship between load and velocity �embed pbrush��� fig. (6) : relationship between deformation and velocity. k(j) �embed pbrush��� fig. (7) : relationship between deformation and kinetic energy. table (6) shows the comparison between three references [3], [4], [5] with the current work. 68 60 _1256459126.unknown _1256459129.unknown _1264194191.unknown _1256459127.unknown _1256459121 _1256459123 _1256459125.unknown _1256459122 _1256459111 _1256459114 _1256459118 _1173207870 <4d6963726f736f667420576f7264202d20e3d1e6ec20e6c7cde3cf20dac8cf20c7e1cdd3ede434332d203534> this is an open access article under the cc by license : al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 18, no. 2, june, (2022) p. p. 4354 intelligent tuning control of two link flexible manipulator with piezoelectric actuator marwah abdulazeem ali* ahmed abdul hussein ali** *,**department of mechanical engineering/ university of baghdad/ baghdad/ iraq *email: m.sareaa1803m@coeng.uobaghdad.edu.iq *email: ahmedrobot65@yahoo.com (received 25 march 2022; accepted 16 june 2022 ) https://doi.org/10.22153/kej.2022.06.001 abstract this paper represents an experimental study on the application of smart control represented by the use of the fuzzy logic controller. two-link flexible manipulators that are used in airspace and military applications are made of flexible materials characterized by low frequency and damping ratio. to solve this problem, this paper proposes the use of smart materials (piezoelectric transducers), where each link is bonded with a pair of piezoelectric transducers that act as a sensor and another as an actuator. as the arm vibrates because of the movement generated by the motor, this voltage is controlled by a regulator inside the labview® 2020 software and sends the output control voltage to the piezoelectric actuator. experimental results show that fuzzy logic control was efficient during high amplitude and led to pronounced results in suppressing vibrations within a short time. fuzzy logic gives more flexibility to the designer and allows him to control the system through its simple implementation. this differs from classical control, which requires a mathematical model. keywords: two link flexible manipulator, active vibration control, smart structure, fuzzy logic control. 1. introduction flexible manipulators that are used in numerous applications like industrial, aerospace, military, and the environment that are dangerous for humans to work in and are replaced by robots are made from flexible and thin materials, which have many advantages like low energy consumption, low weight, and high speed [1]. although it has benefits, it also has negative characteristics, and those are vibrations. because robots are limited by their dynamic behavior due to low frequency and low stiffness, these vibrations lead to problems between the high speed and the accuracy that’s required. the two-link manipulator consists of two cantilever beams and two joints with a dc servo motor, where the flexible link is attached to rigid actuators, such as motors. flexible materials with less damping and lighter weights are more susceptible to dynamic loads caused by environmental factors and human activity [2]. the stability of these flexible materials is proven by the kinetic force and the rotational load, which generate many separate vibrations, and the flexible link produces a large number of amplitudes through a continuously varying force in time. vibrations can affect a variety of aspects, including sensitivity and accuracy [3]. active vibration control proposes vibration mitigation and the generation of an opposing force equal to the action force that creates vibration, which has an effect on the system's stability and performance. there are numerous control algorithms, both classical and intelligent, that can cope with the vibration suppression of flexible structures; fuzzy logic control is used to control the system [4]. to eliminate additional noise from machinery, smart material piezoelectric (sensor/actuator) is used. it can generate an electrical signal when it is under mechanical stress, and this is called the sensor [5]. marwah abdulazeem ali al-khwarizmi engineering journal, vol. 18, no. 2, p.p. 2942 (2022) 44 when used as an actuator, it produces an electrical signal to generate a mechanical stress opposite to the initial stress in order to obtain damping. this is called the actuator. the behavior of the piezo can be summarized in two ways: direct effect and reverse effect. these smart materials have active vibration control that is used to suppress vibration [6]. these manipulators are mathematically modeled using a variety of methods, including finite element methods (fe) and assumed mode methods (amm), with flexible manipulators using the lagrange equation and euler's brnoilly to drive the equation of motion [5]. these structures with piezoelectric material besides control are called "smart structures." research performed a lot of work on controlling the vibration of the manipulator. luiz et al. [6] worked on the fuzzy logic controller to control the vibration on the steel cantilever beam using no mathematical model, just the identification of input-output and the rules of fuzzy logic. a fuzzy controller was developed for effective control performance on a piezo actuator. the experimental results suggest that the current control mechanism is effective. [7]. kamel, et al. analyzing the effects of various controllers on system performance using finite element analysis (fea), works on vibration control using a new dynamic model. three additional intelligent controller methods were examined to improve system performance. pid-at (pid auto-tuning), pd, and stfc (self-tuning fuzzy controller). the system with stfc has the least overshoot, rise time, and improved performance because the rise time was so near to steady-state. this paper presents an intelligent control strategy for regulating two links of a manipulator, which is modeled as two flexible cantilever beams contacted by two joints with a translation base (dc-servo motor). the contribution of this paper is to suppress the vibration in the two links of a flexible, smart robot. and intelligent tuning of the pzt sensor signal. to achieve this, an active vibration control process is applied. one of the active vibration control algorithms with five membership functions and 25 rules is selected for regulating the pzt sensor signal in the two beams. experimental results indicate the satisfactory control performance and robustness of the adopted control schemes. the fuzzy logic controller cuts out a lot of steps and makes the control process easier to understand. 2. mathmetical modeling a mathematical model of the structure is required for placing the piezoelectric. the eulerbernoulli beam theory, piezoelectric theory, dynamics theory, control's state space theory, and functional analysis are all used to create the mathematical model [8]. to generate the dynamic equation of motion, all mathematical models are subjected to generalized global transformations, resulting in a state-space model of the plant that may be used for any type of controller design. the finite element method (fem) divides a flexible aluminum cantilever beam of sufficient size into four finite elements to gain the smart structure's final dynamic equation [9]. an external force operates on the two beams when the motor rotates at a specific angle. as illustrated in fig.1, there is a transverse displacement u as well as bending moments �� and �� at node 1 (fixed end) and node 2 of the beam element, respectively. the deflection behavior of the flexible cantilever beam element is studied using the displacement function u (x, t). marwah abdulazeem ali al-khwarizmi engineering journal, vol. 18, no. 2, p.p. 2942 (2022) 45 fig. 1. smart flexible beam bonded with piezoelectric as (sensor/actuator) divided into 4 finite element. the dynamic equation of sensor output of the smart manipulator which is comprise regular beam element equation and piezoelectric beam element is given by [10]: ��� � ��� � � �� � ��� …(1) ���� ����� ���� …(2) where, � and �, are the global mass and stiffness matrices of the smart beam, respectively, �̈ and � are the acceleration and displacement vectors, �� and ���are the external force applied to the beam and the controlling force from the actuator, respectively. equation (3) is the state space model of the smart structure is developed for 2 vibratory modes (fundamental & 1st harmonic) and equation 4 is the output sensor [8,9]. �������������� � 0 !�"� #�"��$ ��������� � � % 0 !�"�&�ℎ� �"�&�ℎ( �)�)�$ � % 0�"�&��( *��� … (3) and sensor output as [8,9] �����$ +0 ���0 ���, ��������� � … (4) which is obtained in state space form as the final mathematical model given by �� ��� -���� � .)��� � /*��� … (5) ���� 0����� � 1 )��� … (6) the two links considered as two smart cantilever beam divided into 4 finite element bonded with pzt. 3. fuzzy logic control for suppression of the vibration in the two-link flexible manipulator, fuzzy logic with different membership functions is used. it requires more design decisions than classical, model-based controllers. the fuzzy logic-based active vibration controller fuzzy logic control is made up of four steps: fuzzification, fuzzy rule, fuzzy inference engine, and defuzzifier [12]. fig. 2 describes the four principal elements of fuzzy logic. the inclusion of the fuzzy logic marwah abdulazeem ali al-khwarizmi engineering journal, vol. 18, no. 2, p.p. 2942 (2022) 46 controller inside the system is crucial, as it starts with the signal captured by the sensor and ends with the signals entering the piezoelectric actuator, as well as the type of system. fig. 2. research method of the system comprises principle fuzzy controller. 3.1 fuzzification the interpretation interface of the input/output parameters is the initial step in creating a fuzzy controller. the vibration amplitude and change rate are represented by the input error (e) and the rate of change of error (er) in this investigation. the voltage signal and its derivative, which can be gotten by a pzt sensor. the output variable u is a voltage (control) signal that is transmitted to piezoelectric actuators through a voltage amplifier. the input domain and output domain are represented by five linguistic levels (nh, ns, ze, ps, ph), which mean "negative high," "negative small," "zero," "positive small" and "positive high," respectively. the membership values range from (-5 to +5) in this study, triangular fuzzy membership functions were chosen.figure 3 depicts the fuzzy control membership function []. fig. 3. membership function of the system control. selecting the range of membership depends on the design of the control system. marwah abdulazeem ali al-khwarizmi engineering journal, vol. 18, no. 2, p.p. 2942 (2022) 47 3.2. fuzzy inference and fuzzy rules the fuzzy controller's control rules are frequently based on experts' experiences and are expressed as if-then rules that link input and output variables. the if-then rule is as follows [14]: if e is nh and er, then u is ph the fuzzy logic system's input and output variables are represented by e, er, and u (error, error change, and output) may reduce the number of control rules for the beam vibration control system using this strategy. the vibration control system is listed in table 1. the first column, error e, and the first row, error rate er, describe the rule. table 1, fuzzy inference rules of the system control. er nh ns ze ps pb u e nh ph ph ph ps ze ns ps ps ps ze ns ze ze ps ze ze ps ps ps ze ns ns ps ph ze ns ns nm ns 3.3 defuzzification the step of converting the fuzzy inference result to numerical output and translating it to an actuator to damp the flexible beam where it bonded and get active control of the system. fig. 4. viewed surface of input/output relationship. 4. experimental setup to suppress the vibrations that occur in the twolink manipulator and help to achieve stability in a short time. fig.5 shows the process diagram for operating the system, starting with the electrical signals for the distortion being got from the piezoelectric sensor, which is then transferred to the data acquisition (daq), and then transferred to the labview program, which is installed on the computer. the whole circuit is regulated by the fuzzy controller within the labview program. the signal is transmitted and amplified by the amplifier and transmitted to the piezoelectric actuator, which generates a mechanical stress to control the vibration in the two-link flexible manipulator. the hardware used in conducting the test is shown in fig. 6. it has an aluminum beam, a piezoelectric patch, a data acquisition ni usb 6353, an e-463 hvpzt amplifier, and a laptop with labview software to control the system. marwah abdulazeem ali al-khwarizmi engineering journal, vol. 18, no. 2, p.p. 2942 (2022) 48 fig. 5. the schematic diagram steps of experimental work. (a) (b) fig. 6. experimental system (a) two-link flexible manipulator,(b) the second link bonded with a piezoelectric actuator. marwah abdulazeem ali al-khwarizmi engineering journal, vol. 18, no. 2, p.p. 2942 (2022) 49 table 2, the flexible manipulator physical and geometrical characteristics, as well as the piezoelectric. physical specification two link flexible manipulator piezoelectric unit length 245 40 mm width 35 23.5 mm thickness 2 0.46 mm density 2810 7870 kg/ 2� young modulus 71 50 gpa 1�� (strain constant) -320*10"�� m/v 4�� (pzt stress constant) -9.5*10"� m/v figure 6 shows the experimental setup it consists of the following parts: first, a two-link flexible manipulator; and second, the measuring and controller part. the smart two-link flexible manipulator is made from two aluminum links. each arm is connected with joints to facilitate movement, which is connected with a dc servo motor to get the movement of the system and control the vibrations deduced from the movement. two dc servo motors are used to move the flexible manipulator about the z axis. the first is positional rotation, which contains strong metal gears that work at 8 volts and provide high torque of 50 kg [16]. the second motors also positionally rotate to provide 30kg of torque at 7 volts, working at a maximum angle rotation of 180 and changing speed according to the angle of rotation 45 degree applied with angular speed. [17] two dc servo motors two dc servo motors are driven by a microcontroller (arduino mega 2560) programmed to the required movement. on its table are four piezoelectric transducers (type ppa1001-5h) with a full scale voltage of 120 volts and a mass of 8 g, as well as steel pads at the end for electrical terminals for energy harvesting and sensing applications [18]. the four piezoelectric bonded on each arm near the fixed end, two on each link, and one sensor and one actuator in one link, are bonded by special adhesive glue. piezoelectric bonded on the beam have two piezoelectric sensors connected with a resistor of 1 megohm to get a constant voltage of up to 10 and don’t exceed it because of daq-mxusb, a piezoelectric sensor used to sense the electrical voltage of the strain in the links. the electric voltage is the measurement of the amplitude. the ni daqmx-6353usb includes a cable that connects to a laptop to acquire data from a piezo sensor and send it to the actuator after being controlled by the ni-labview® 2020 software. as shown in schematic diagram fig.4, daq has analog input and output. the output control voltage will be amplified from (6) to 24 times by the (hvpzt-e463) high voltage piezo amplifier and reach 144 to drive the piezo electric actuator. 5. results and discussion. the experiment has been done according to specific velocity and angular rotation to verify the validity of suppression vibration of the designed two-link manipulator and adopt fuzzy logic control. in the experiments, both the degree and angular rotation of the two dc-servo motors are (and =35 r/s, and =45 r/s) via arduino. the ability to suppress vibration of the two-link manipulator is the basic concept in this system. the velocity and delay must be low because that may lead to the destruction of the two-link manipulator. the aim of the movement of the two motors is to get the excited vibration required to verify the active control in the two-link manipulators. fig.7 shows that the maximum overshoot is 5.27v and the settling time is 14 s to be in a steady state for the first link and for the second link, as shown in fig.8, the greatest the maximum overshoot observed is 2 v, which is less than the electrical signal coming out of the first link because the motor that drives the first link has higher torque than the second. fig. 9 shows the effectiveness of the fuzzy controller in reducing the electrical signal after applying the membership; it reached 0.3v, which is a very low value compared to 5.27v. referring to this extent does not mean getting better damping and regulation, as in fig.11, it was reduced to 0.19v. figures 10 and 12 show an enlarged part of figures 9 and 11, respectively, which show the shape of the wave after the regulation, where there are very small waves that need some kind of control, like classical control (pi, pd, or pid) to keep their regulation. marwah abdulazeem ali al-khwarizmi engineering journal, vol. 18, no. 2, p.p. 2942 (2022) 50 fig. 7. vibration response of the first link without active control flc. fig. 8. vibration response of the second link without active control flc. fig. 9. vibration suppression and time response under flc for the first link. marwah abdulazeem ali al-khwarizmi engineering journal, vol. 18, no. 2, p.p. 2942 (2022) 51 fig. 10. enlarged shape of vibration suppression and time response of first link under flc. fig. 11. vibration suppression and time response under flc for second link. fig. 12. zoom in vibration suppression and time response of second link under flc. marwah abdulazeem ali al-khwarizmi engineering journal, vol. 18, no. 2, p.p. 2942 (2022) 52 aovershoot of vibration of first link. bovershoot of vibration of second link. fig. 13. comparisons of maximum overshoot of the two links with and without fuzzy logic control. the maximum overshoot of the system was reduced after applying fuzzy logic control in the two beams, as shown in fig.13, which means the system's noise was reduced, and thus the vibration was reduced. 6. conclusions an intelligent control represented by the fuzzy logic controller has been used to improve the control of a two-link manipulator operated by dc servo motors using the built-in experimental apparatus and to control the vibrations that occur in it. piezoelectric materials are used in the performance and to control the voltage coming out of the sensitive piezoelectric material by the fuzzy. the experimental results taken from the piezoelectric sensor of the two-link manipulator showed that fuzzy logic has a high effectiveness in suppressing large amplitudes. the damping occurs at nearly 40–35% in the smart two-link manipulator. the disturbance's robustness has also been addressed. 7. references [1] lu, s. f., jiang, y., zhang, w., & song, x. j, “ vibration suppression of cantilevered piezoelectric laminated composite rectangular plate subjected to aerodynamic force in the hygrothermal environment” european journal of mechanics, a/solids, 83.2020. 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[14] ali, a. a., lateef, r. a. r., & saeed, m. w. “ intelligent tuning of vibration mitigation process for single link manipulator using fuzzy logic” engineering science and technology, an international journal, 20(4).2017. [15] “datasheet of 50kg. cm metal gear servo motor waterproof ", china,2020. https://www.uruktech.com/product/50kg-cmservo-motor. [16] “datasheet of 30kg. cm metal gear servo motor waterproof ", china,2020. https://www.uruktech.com/product/30kgservo-motor/ [17] national instrument, “datasheet of pi physik instrumente e-463 hvpzt amplifier 3channel piezo”. usa .2019. [18] ppa-1001,” datasheet, mide co.ltd”., ppa-series ,usa,2019. )2022( 4354، صفحة 2العدد، 18مجلة الخوارزمي الهندسية المجلد مروة عبد العظيم علي 54 ضبط الذكي للتحكم في وصلة مناور مرن مع مشغل كهروظغطي احمد عبد الحسين علي** مروة عبد العظيم علي* *،**قسم الهندسة الميكانيكية/ كلية الهندسة/ جامعة بغداد/ العراق m.sareaa1803m@coeng.uobaghdad.edu.iq*البريد االلكتروني: ahmedrobot65@yahoo.com**البريد االلكتروني: الخالصة يمثل هذا البحث دراسة تجريبية على تطبيق التحكم الذكي المتمثل في استخدام متحكم المنطق الضبابي. مناور مرن ثنائي الوصلة يستخدم تقترح هذه المشكلة،وهو مصنوع من مواد مرنة تتميز بالتردد المنخفض ونسبة التخميد. لحل هذه العسكرية،في المجال الجوي والتطبيقات الورقة استخدام مواد ذكية (محوالت طاقة كهرضغطية) ، حيث يتم ربط كل وصلة بزوج من محوالت الطاقة الكهروضغطية التي تعمل كمستشعر ®labview يتم التحكم في هذا الجهد بواسطة منظم داخل برنامج المحرك، تي يولدها وآخر كمشغل. عندما يهتز الذراع بسبب الحركة ال ويرسل جهد التحكم في الخرج إلى المشغل الكهروإجهادي. تظهر النتائج التجريبية أن التحكم المنطقي الضبابي كان فعاالً أثناء السعة 2020 ون فترة زمنية قصيرة. يمنح المنطق الضبابي مزيدًا من المرونة للمصمم ويسمح العالية وأدى إلى نتائج واضحة في قمع االهتزازات في غض .له بالتحكم في النظام من خالل تنفيذه البسيط. هذا يختلف عن التحكم الكالسيكي الذي يتطلب نموذًجا رياضًيا this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 19, no. 2, june, (2023) p. p. 6881 fabrication and analysis of denture plate using single point incremental sheet forming hassan saad* ahmed z. m. shammari** salah s. abed alkareem*** *,**,***department of automated manufacturing engineering/ al-khwarizmi college of engineering/ university of baghdad/ baghdad/ iraq *email: hassansaad1975@gmail.com **email: ahmadhzaam@yahoo.com ***email: salah.s@kecbu.uobaghdad.edu.iq (received 28 november 2022; accepted 20 february 2023) https://doi.org/10.22153/kej.2023.02.001 abstract incremental sheet forming (isf) is a metal forming technology in which small incremental deformations determine the final shape. the sheet is deformed by a hemispherical tool that follows the required shape contour to deform the sheet into the desired geometry. in this study, single point incremental sheet forming (spif) has been implemented in dentistry to manufacture a denture plate using two types of stainless steel, 304 and 316l, with an initial thickness of 0.5mm and 0.8mm, respectively. stainless steel was selected due to its biocompatibility and reasonable cost. a three-dimensional (3d) analysis procedure was conducted to evaluate the manufactured part's geometrical accuracy and thickness distribution. the obtained results confirm the capability of spif to produce thin-walled biomedical components with satisfactory dimensional accuracy, as geometrical deviations between the developed and the actual models are predominantly in the range of ±0.25mm. keywords: denture base plate, single point incremental sheet metal forming (spif), thickness distribution, 3d analysis. 1. introduction incremental sheet forming is a flexible and innovative process that can be used in rapid prototyping and batch production; it requires no dies and no special tools and can be performed to produce customized and tailored products [1]. the process uses a hemispherical tool that deforms the sheet into the desired geometry. the final shape (3d model) is accomplished by dividing it into 2d levels so that the tool proceeds to the upcoming contour after finishing the present contour [2]. the main limitation of this process can be summarized as the lengthy manufacturing time, and the poor geometrical accuracy compared to other manufacturing processes. the poor geometrical accuracy can be attributed to the sheet bending and spring back. furthermore, the pillow effect (a protrusion originating at the center of the spif made part) also accounts for the poor accuracy [3]. a schematic diagram that summarizes the single point incremental sheet forming is shown in figure 1, in which the sheet is fixed on a clamping frame and supported by a backing plate to reduce geometrical inaccuracies caused by the sheet bending. the sheet is formed by the repeated application of a minor, controlled force at a single point. the forming tool is moved incrementally along the sheet, applying force at each point and gradually forming the sheet metal into the desired shape [4]. mailto:hassansaad1975@gmail.com mailto:ahmadhzaam@yahoo.com mailto:salah.s@kecbu.uobaghdad.edu.iq https://doi.org/10.22153/kej.2023.02.001 hassan saad al-khwarizmi engineering journal, vol. 19, no. 2, p.p. 6881 (2023) 69 fig. 1. principle of the single point incremental forming process [4] the most significant area in which single point incremental sheet forming has been employed is in the automobile and aerospace industry [5]. spif is considered a relatively new technology in the manufacturing of biomedical implants. the first application of spif in the medical field was the fabrication of ankle support which was successfully manufactured without any die and with a sufficient geometrical deviation [6]. the most common application of spif in the biomedical field is the production of cranial implants. the cranial prosthesis was fabricated using biocompatible materials such as polymeric sheets [7] and titanium [8]. other applications of spif regarding biomedical implants are the manufacturing of knee prostheses [9], facial implants [10], and clavicle implants [11]. a denture plate is a major dental prosthetic of a complete denture that replaces missing teeth and is positioned in the roof of the mouth in the oral cavity [12]. the most common material used in the fabrication of dentures is polymethyl methacrylate (pmma). however, due to several disadvantages, such as brittleness which leads to fracture [13], it is crucial to strengthen the denture with materials that impede the rupture and one of the most effective ways to ensure a steady performance is to incorporate it with a metal plate or wire [14]. the most common technique used to fabricate the denture plate is the lost wax technique (conventional method). in addition, in the last twenty years, several technologies have been developed to produce dental components, such as rapid laser forming [15], additive manufacturing [16], and selective laser melting [17]. however, the main problem in the field of dentistry is that there is a particular demand for new technologies to replace conventional techniques that are based on casting technology, as they require a high degree of skill, high equipment costs and high processing times, and spif is a promising technology that can be applied in these types of applications. as opposed to the medical field, research is scarce concerning spif technology in the dental field. m.sbaytietal. [18] applied single point incremental sheet forming to fabricate a titanium denture plate with a satisfied geometry by providing an optimization strategy based on numerical simulation and finite element analysis. in addition, m. milutinovic et al. [19] used lowcarbon steel (en dc04) and manufactured a denture base with acceptable geometry. in our study, we used two types of stainless steel. the type 316l is one of the most widely used materials in biomedical applications, however, there has never been a study about this material in incremental sheet forming applications. taking the previously mentioned into consideration, the main purpose of this study is to investigate the ability of spif to be applied in the field of dental restorations by evaluating the geometrical accuracy and thickness distribution of the fabricated parts to determine if spif is capable of producing a geometrically correct dental plate using stainless steel sheets. 2. material and mechanical properties stainless steel is one of the most used metals in biomedical implants for cardiovascular, dentistry, craniofacial, and orthopedic applications [20]. this is due to its good mechanical properties, acceptable biocompatibility, and reasonable cost compared to titanium, cobalt, and vanadium alloys [21]. the most common stainless steel used in dentistry is the austenitic series 300, which has been utilized widely in the manufacturing of crowns, dental bridges, and orthodontic wires [22], especially the 316l stainless steel type. however, stainless steel made implants can only be used for a short term due to their poor corrosion resistance, which increases the infection risk [23]. the chemical compositions of 304 and 316l stainless steel are listed in table 1. the mechanical properties of the materials were obtained using the tensile test. the tensile test provides information about the material’s ductility and flow stress, as these properties are key factors that affect the isf process. the ductility is used as a formability indicator for the materials during the forming process to ensure the successful implementation of isf. at the same time, flow stress (the initial yielding and tensile stress) determines the forming load and the contact pressure between the tool-sheet interfaces. using hassan saad al-khwarizmi engineering journal, vol. 19, no. 2, p.p. 6881 (2023) 70 a united universal hydraulic testing machine, the tests were executed for 316l and 304 stainless steel sheets of 0.8 and 0.5mm. three tensile test specimens having different orientations with respect to the sheet rolling direction were cut from each sheet: 0ᵒ to the rolling direction, 45ᵒ diagonal to the rolling direction, and 90ᵒ transverse to the rolling direction.the tensile test specimens were fabricated according to the standard for the traction testing of metallic materials, sr en 100021: 2002. the mechanical properties are listed in table 2. concerning material ductility, both materials exhibited good elongation characteristics, and with the consideration of the increased formability that isf offers compared to the tensile test, it can be reasonable to assume that both materials have good potential to be used in isf processes. fig. 2. tensile test specimen dimensions (mm) taken at different rolling directions. table 1, chemical composition of stainless steel 304 and 316l (content%) material c mn fe si cr al ni pb mo 304 0.0479 1.04 70.7 0.630 18.2 0.0189 8.46 0.0020 316l 0.0328 1.96 66.8 0.335 17.8 0.413 9.26 0.0250 1.77 table 2, mechanical properties of stainless steel with respect to the rolling direction. material rolling angle ultimate tensile strength (mpa) yield strength (mpa) elongation (%) 316l 0 45 90 638.03 649.80 667.02 370 358.66 410 46.25 43.75 45 304 0 45 90 620.78 651.02 677.38 258 275 300 58.75 55 53.75 3. process design this section consists of three parts. the first part focuses on the computer-aided design (cad) modeling aspect of the denture plate, whereas the second and third sections focus on the computeraided manufacturing (cam) modeling and experimental work. the methodology used for manufacturing the denture plate is presented in figure 3. hassan saad al-khwarizmi engineering journal, vol. 19, no. 2, p.p. 6881 (2023) 71 fig. 3. workflow methodology applied in the manufacturing of the denture plate. 3.1. cad modeling of denture base the manufacturing process of a denture base starts with the creation of a denture base cad model. by applying the reverse engineering concept, the cad model of a denture base can be acquired either by using medical imaging techniques such as magnetic resonance imaging (mri) or computer tomography scan (ct) of the patient’s jaw or by digitizing a master cast (a cast that replicates the entire oral structure) of the patient’s mouth. in this research, a gypsum working cast was scanned using a desktop scanner (medit t710). multiple overlapping scans were taken to produce the cast in the standard triangulation language file format (stl) to achieve maximum scanning accuracy. the acquired geometrical data was then imported into cad software (exocad) to create the denture plate model. the cad software was chosen due to its high capability of designing dental prostheses and implants. the cad modeling process of the denture plate is presented in figure 4. fig. 4. cad modeling process. hassan saad al-khwarizmi engineering journal, vol. 19, no. 2, p.p. 6881 (2023) 72 3.2. tool path generation after developing the denture base cad model, the second step will be generating the tool path required to manufacture the denture plate. the tool path is a significant step in incremental sheet forming since it strongly influences manufacturing time, surface finish, thickness distribution, and geometrical accuracy. the tool path consists of points representing the contact between the tool and the sheet along a programmed and confined space. the spif process is similar to the milling process, which enables commercial cam software to generate the tool path and nc code for the milling machine. in this research, autodesk fusion 360 was used to generate the tool trajectories in spif. the tool path strategy selected to fabricate the denture plate is contour milling, and was programmed to manufacture two denture bases simultaneously. the implant perimeter is open, a region must be constructed to join the perimeter and create a closed space for the tool to move. the process parameters were selected to achieve a highquality surface finish. they were chosen according to the findings in [24] and [25] and for both materials (304 and 316l): a stepdown of 0.02 mm, a tool diameter of 10 mm, a spindle speed of 110 rpm, and a feed rate of 1000mm/min. after performing the simulation, the computer numerical controlled (cnc) machine codes had to be postprocessed to create a g-code specific to the cnc machine where the denture plate was fabricated. the cam modeling process is shown in figure 5. fig. 5. cam modeling process. 3.3. experimental setup the manufacturing process was carried out using a c-tek three-axis (km-80d) cnc vertical milling machine, as shown in figure 6 (a), equipped with a maximum spindle speed and feed rate of 6000 rpm and 10000mm/min. the forming tool was made from high-speed steel (molybdenummax cobalt high-speed steel, m42) and designed with a hemispherical tip (10mm diameter). as shown in figure 7. the forming fixture frame was built and designed by [26] and is mounted on the cnc machine to fix the sheet during the manufacturing process. the initial blank dimensions were 225mm×225mm, and a thickness of 0.5 and 0.8 for 304 and 316l, respectively. the frame consists of a square blank holder and a square backing plate. the backing plate was made from mild steel with dimensions of 225mm×225mm×5mm with a profile-specific hole, as shown in figure 6 (b). the profile-specific hole represents the cad model's top view (x-y) plane to ensure maximum accuracy and correlation with the tool path and minimize geometrical deviation caused by sheet bending and material spring back. the hole was made with an offset of 2mm to account for sheet thickness and tool material. lubrication was applied between the tool and the sheet to reduce friction and tool wear. the manufacturing process of the denture plate is shown in figure 8. hassan saad al-khwarizmi engineering journal, vol. 19, no. 2, p.p. 6881 (2023) 73 fig. 6. experimental setup. fig .7. tool dimensions (mm). fig .8. manufacturing process of the denture plate. 3.4. measurement procedure a three-dimensional (3d) comparison analysis to evaluate the geometrical discrepancies between the manufactured parts and the reference cad model was conducted by using gom to inspect the 3d data test software. the scanned blank dimensions were 80×60mm as the sheets’ excess material was removed for the blank to be scanned. the external surfaces of the 304 and 316l denture bases were scanned using the meditt710 lab scan, as shown in figure 9. the lab scan consists of four 5.0 mp camera systems and employs blue light scanning technology, ensuring high scanning accuracy (<4 μm). the scanned data (points of clouds) were reconstructed to the stl model to be imported into the gom inspect software. the analysis starts by defining the scanned data (stl) as the actual model and the designed cad model as the reference model. the scanned data and the cad model were aligned (as shown in figure 10) using the pre-alignment strategy to detect hassan saad al-khwarizmi engineering journal, vol. 19, no. 2, p.p. 6881 (2023) 74 dimensional discrepancies and generate the deviation map. the outcome of this analysis is represented graphically, as shown in figures 11 and 12. colors represent different geometrical deviations along the part in mm. negative values show that the produced part has failed to reach the desired profile. in contrast, the positive values indicate that the produced part has exceeded the designed profile. fig. 9. scanning process of the manufactured part. fig. 10. alignment between the scanned data and cad model. 4. results and discussion 4.1. geometrical accuracy denture fit is an essential aspect that determines the quality of the produced denture, as it ensures the patient’s comfort with wear and reduces or prevents traumatic ulcers in the mouth. thus, manufacturing a denture plate with satisfactory dimensional accuracy is essential to ensuring the patient’s comfort [27]. in our study, both stainless steel prototypes (304 and 316l) showed similar results, as shown in figures 11 and 12. the deviation between the developed and actual models primarily ranged between ±0.25 mm. the obtained results are considered within the clinically acceptable tolerances of 0.311mm [28]. therefore, the obtained results are judged to be satisfactory. furthermore, in comparison to the traditional method (lost wax technique), the results are similar to those obtained by [29], who measured the average dimensional gaps of the conventionally fabricated models with the reference model to be between 0.15 to 0.28mm. in addition, the results are also comparable to the most common cadcam techniques that are currently being used in the fabrication of denture prosthetic bases, such as the subtractive milling process (primarily ranging around 0.2 mm) and the additive manufacturing method (3d printing) (primarily ranging around 0.16mm) [30]. taking these facts into account, it can be considered that spif technology has the potential to be applied in dentistry to fabricate metal dental prostheses. in addition, the manufacturing time is highly reduced (1 hour) hassan saad al-khwarizmi engineering journal, vol. 19, no. 2, p.p. 6881 (2023) 75 compared to the milling process (5 hours), and 3d printing (1.3hours) [31]. the deviation map shows that the maximum errors are located at the edge of the parts in the regions closest to the clamping plate, which can be ascribed to the sheet bending during the forming process, as these regions are under excessive bending stress since they are the nearest to the backing plate and the farthest from the tool. geometrical inaccuracies caused by the bending effect during the forming process are one of the primary origins of geometrical errors in the spif process. however, from a dental perspective, high dimensional error in this region is not of significant concern since artificial teeth, and acrylic resin will further pad them [19]. one possible way to minimize the bending effect and improve the overall geometrical accuracy is the application of double-sided incremental forming (dsif), in which an additional supporting tool is utilized during the forming process. in contrast, regions located at the bottom part and the walls of the denture plate have a slight and uniform geometrical deviation. as geometrical deviations in these regions are commonly affected by the pillow effect, it can be concluded that the pillow generation was minimized and didn’t produce significant inaccuracies. furthermore, the dimensional discrepancies detected in the prototype made from 0.5mm 304 stainless steel showed a slight improvement in dimensional accuracy compared to the 0.8 mm 316l prototype, which can be attributed to the lower sheet thickness, which exhibits less spring-back. fig. 11. geometrical deviation accuracy map for (0.5mm) stainless steel 304 denture plate. fig. 12. geometrical deviation accuracy map for (0.8mm) stainless steel 316l denture plat. 4.2. thickness distribution one of the significant drawbacks of incremental sheet forming is sheet thinning, which has an adverse effect on the formed parts in terms of geometrical accuracy, formability, and strength. in fact, when the formed part reaches its forming limit, thinning can lead to its cracking. thus, it is crucial to evaluate the thickness distribution of the formed components. hassan saad al-khwarizmi engineering journal, vol. 19, no. 2, p.p. 6881 (2023) 76 in this research, the thickness distribution was measured by scanning the entire part (internal and external surfaces of the formed component). the thickness distribution was measured using the gom inspection software. the results showed that the thickness remained unchanged at the bottom of the plate for both types of stainless steel (304 and 316l) with initial sheet thicknesses of 0.5mm and 0.8mm. the most affected zones are located along the lateral and front walls of the plate, with a maximum thickness reduction of 50% as thinning intensity has increased at regions with high wall angles. from a dental point of view, this is highly desirable as it ensures mass reduction, which as a result, increases the comfort of wear for the patients [32]. however, additional tests are required to evaluate the strength of the parts to verify if this mass reduction affects the performance of the plate. the early results are promising; milutinovic et al. [25] performed mechanical tests (stiffness and flexural strength) to evaluate the performance of the spif-made denture plate from stainless steel 430 with 0.5mm thickness, in which a thickness reduction of about 60% was recorded. the study’s results revealed that the produced denture plate using spif technology had satisfactory mechanical properties and even exhibited similar performance to a conventionally produced denture plate (using the lost wax technique) with a thickness of 0.8mm. in conclusion, additional tests are still necessary to assess the performance of the produced denture plate, especially in the long term. thickness distribution for the 304 and 316l parts is presented graphically in figures 13 and 15. fig. 13. distribution of final sheet thickness of (0.5mm) 304 stainless steel. fig. 14. sheet thickness distribution along the section (x-x). hassan saad al-khwarizmi engineering journal, vol. 19, no. 2, p.p. 6881 (2023) 77 fig. 15. distribution of final sheet thickness of 316l stainless steel. fig. 16. sheet thickness distribution along the section (i-i). 5. conclusions single point incremental sheet forming has been successfully implemented to produce a denture plate from two types of stainless steel, 304 and 316l, with initial thicknesses of 0.5mm and 0.8mm, respectively. the reported results demonstrated that the process is feasible and can be used in real-life medical applications. compared to the traditional way of impression taking and model waxing, which requires a high degree of skill, high equipment costs, and high processing times, this process can minimize the working hours of dental clinicians and cut production costs significantly. the process was performed using a universal cnc vertical milling machine and required no preparation of shape-specified tools. the main conclusions of this work can be summarized as follows: 1. the process can be realized by developing a 3d model of the biomedical component, tool path generation, g-code transfer to the cnc machine, and the preparation of a customized backing plate to reduce the geometrical deviation. 2. geometrical deviations between the developed cad model and the actual model are predominantly in the range of ±0.25mm. the highest geometrical deviation was located at the upper zone of the deformed sheet. this geometrical shift can be attributed to the bending effect during the forming process at regions bordering the backing plate. 3. thickness distribution was analyzed for both hassan saad al-khwarizmi engineering journal, vol. 19, no. 2, p.p. 6881 (2023) 78 plates of stainless steel. the thickness was almost unchanged at the bottom of the plates and around the edges. the most critical zones with extensive thinning were located at the lateral and front walls. future work and recommendations 1. similar work can be implemented using biocompatible polymeric materials such as polyether ether ketone (peek) and polymethyl methacrylate (pmma), as polymer processing using spif is a relatively new technology, and research is scarce regarding these materials. 2. the implementation of double-sided incremental sheet forming (dsif) as this technology can highly reduce the geometrical deviations caused by the bending effect of the sheet. 3. the performance of a comparison between the spif-made denture plate and the commercial one regarding performance, cost, biocompatibility, and accuracy. 4. more work is required to concentrate on the technical parameters used during the manufacturing process to improve the obtained accuracy. list of abbreviations isf incremental sheet forming spif single point incremental sheet forming dsif double-sided incremental sheet forming cad computer-aided design cam computer-aided manufacturing stl standard triangulation language format cnc computer numerical control ct computerized tomography mri magnetic resonance imaging 6. references [1] a. s. baden, “optimization and prediction of process parameters in spif that affecting on surface quality using simulated annealing algorithm,” alkhwarizmi engineering journal, vol. 12, no. 4, pp. 81–92, 2017. 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(2023) 68-81، صفحة 2، العدد19مجلة الخوارزمي الهندسية المجلد حسن سعد إسماعيل 81 تصنيع وتحليل لوحة طقم األسنان باستخدام تشكيل الصفيحة اإلضافية بنقطة واحدة احمد زيدان** صالح صبيح*** حسن سعد إسماعيل* جامعة بغداد*،**،***قسم هندسة التصنيع المؤتمت/ كلية الهندسة الخوارزمي/ gmail.com1975hassansaad@:*البريد االلكتروني ahmadhzaam@yahoo.com **البريد االلكتروني: salah.s@kecbu.uobaghdad.edu.iq***البريد االلكتروني: لخالصةا يھادتؤ لتيا نیةورالدا تلحركاا من سلسلة ريقط عن لمعدنیةا لصفائحا تشكیل عملیة في لحديثةا تلتقنیاا من لصفائحيا لتشكیلا عملیة تعد تشكیل يتم لعملیةا هذھ لخال من. لمبرمجا لتشغیلا ماكنة قبل من ةلعدا هذھ حركة تتمو. متسلسل بشكلو ةحدوا تشكیل نقطة في لتشكیلا ةعد تصنیع تعملیا لمجا في لتقنیةا اذھ امستخدا على بالتركیز ميقو لبحثا اذھ. لنقيا لسحبا عملیة امستخدا لخال من نیةا رةبصو لصفائحا لصفیحةا كانت فیما اءألجر أللصد وملمقاا ذلفوالا من صفیحیتین رختیاا تم. نسناا قمط ةقاعد تصنیع عملیة في باالخصو لطبیةا تلتطبیقاا ذجلنموا تصمیم تم. ملم (0.8) لىوالا لصفیحةا. لتصنیعا عملیة ملم( 0.5) بسمك( و 304) وعن من كانت بسمكو (316l) عنو من لثانیةا عملیة تمت (exocad). ببالحاسو نمعا لتصمیما برنامج امبأستخدو نسناا لقالب scanning) (3d دالبعاا ثالثي مسح بعملیة ملقیاا ريقط عن لنقطيا لتشكیلا عملیةان لنتائجا ثبتتأ. لمصمما ذجلنمووا لمنتجةا تلعیناا بین دالبعاا ثالثیة نةرمقا عمل ريقط عن لمنتجةا تلعیناا قةد فحص ملم 0.25± بین اوحيتر لمصمما ذجلنمووا لمنتجةا تلعیناا بین وتلتفاا نكا حیث لطبیةا تلصناعاا من علنوا الھذ مالئمة للصفائح . mailto:hassansaad1975@gmail.com mailto:ahmadhzaam@yahoo.com abstract 3. process design 3.1. cad modeling of denture base 3.2. tool path generation 3.3. experimental setup 3.4. measurement procedure 4. results and discussion 5. conclusions future work and recommendations list of abbreviations 6. references this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 21, no. 1, march (2025), pp. 13-27 deep-learning-based mobile application for detecting covid-19 noor kamal al-qazzaz1*, alaa a. aldoori2, tabarak emad hussein3, massarra mohammed mahdi4, sawal hamid bin mohd ali5, and siti anom ahmad6 1,2,3,4department of biomedical engineering, al-khwarizmi college of engineering, university of baghdad, baghdad, iraq 5department of electrical, electronic & systems engineering, faculty of engineering and built environment, universiti kebangsaan malaysia, ukm bangi, selangor 43600/ malaysia centre of advanced electronic and communication engineering, department of electrical, electronic and systems engineering/ universiti kebangsaan malaysia, selangor 43600, malaysia 6department of electrical and electronic engineering, faculty of engineering, universiti putra malaysia, upm serdang, selangor 43400, malaysia malaysian research institute on ageing (myageing™), universiti putra malaysia/ serdang, selangor 43400/ malaysia *corresponding author, s email: noorbme@kecbu.uobaghdad.edu.iq (received 18 march 2024; revised 1 december 2024; accepted 22 december 2024; published 1 march 2025) https://doi.org/10.22153/kej.2025.12.001 abstract patients infected with the covid-19 virus develop severe pneumonia, which typically results in death. radiological data show that the disease involves interstitial lung involvement, lung opacities, bilateral ground-glass opacities, and patchy opacities. this study aimed to improve covid-19 diagnosis via radiological chest x-ray (cxr) image analysis, making a substantial contribution to the development of a mobile application that efficiently identifies covid-19, saving medical professionals time and resources. it also allows for timely preventative interventions by using more than 18000 cxr lung images and the mobilenetv2 convolutional neural network (cnn) architecture. the mobilenetv2 deeplearning model performances were evaluated using precision, sensitivity, specificity, accuracy, and f-measure to classify cxr images into covid-19, non-covid-19 lung opacity, and normal control. results showed a precision of 92.91%, sensitivity of 90.6, specificity of 96.45%, accuracy of 90.6%, and f-measure of 91.74% in covid-19 detection. indeed, the suggested mobilenetv2 deep-learning cnn model can improve classification performance by minimising the time required to collect per-image results for a mobile application. keywords: deep learning; cnn; mobilenet-v2; image processing; covid-19; lung opacity; mobile display 1. introduction on december 31, 2019, the covid-19 pandemic officially started after the first pneumonia report with unidentified aetiology appearing in wuhan, china [1,2]. initially known as sars-cov2, the world health organization (who) later designated it as covid-19 owing to its infectious nature. on january 30, 2020, the who formally categorised the covid-19 pandemic as a public health emergency of international concern [3]. on july 21, 2020, the who classified around 9 million of the 15 million confirmed covid-19 cases worldwide as active. tragically, the virus has claimed the lives of 614,208 individuals globally [4]. the predominant manifestations of covid-19 include pyrexia, nasal discharge, paroxysmal mailto:noorbme@kecbu.uobaghdad.edu.iq https://doi.org/10.22153/kej.2025.12.001 noor kamal al-qazzaz al-khwarizmi engineering journal, vol. 21, no.1, pp. 1327 (2025) 14 expulsion of air from the respiratory tract, pharyngeal discomfort, inflammation of the throat, cephalalgia, diminished physical strength, general discomfort, and respiratory distress [5]. the timely identification of sickness enhances the likelihood of effective treatment for afflicted individuals and concurrently diminishes the risk of transmission amongst the community, particularly in the case of a communicable ailment such as covid-19 [6]. many countries also offer laboratory tests that use real-time reversetranscription polymerase chain reaction (rt-pcr), the most widely used technology for covid-19 detection [7]. however, the rt-pcr test sensitivity is only 60%–70%. therefore, identifying the harmful consequences of covid-19 by looking at patient lung images can ensure early treatment. chest radiological imaging such as x-rays and computed tomography (ct) scans plays a significant role in the early detection and therapy of this illness. one advantage of x-rays is their ease of use with portable x-ray tools, leading to a faster and more effective diagnosis of covid-19. with the help of artificial intelligence (ai), x-rays may be able to find covid-19, causing less bodily damage than ct scans [2,8]. various ai-based techniques have assisted in recent efforts to locate covid-19 using images [2]. ai techniques are currently being discovered to be exceedingly advantageous for the purposes of testing, training, and evaluation. prediction models are frequently constructed using neural networks. however, neural networks continue to possess constraints, such as their learning capacity and delayed convergence [9]. deep learning enhances diagnostic speed by facilitating clinical decisions and predictions within the medical system. researchers are currently investigating deep learning, a subfield of machine learning, for its ability to automatically extract significant characteristics from datasets using neural networks like artificial neural networks, where recurrent neural networks and convolutional neural networks (cnn) play key roles. they are particularly useful for categorising data because they enable computers to learn from it and deliver accurate answers [10]. recently, image classification with cnns has effectively diagnosed common chest disorders, including tuberculosis screening and mediastinal lymph nodes in ct images. numerous real-world applications such as pattern recognition and intuitive picture categorisation have extensively used cnn, one of the most effective deep-learning architectures [11]. cnns can function in many ways using pre-trained cnns with feature extractors [12]. nevertheless, the use of deep-learning approaches to identify and detect new covid-19 in x-rays up to this point is rare [9]. using radiological images such as x-rays or ct scans, medical imaging can be considered a critical technique for diagnosing covid-19 infections and assisting doctors in evaluating the disease, as well as in optimising prevention and control measures, as early as feasible. therefore, medical images with the diagnostic parameters are a highly effective approach that can enable physicians to diagnose patients with the help of big data [13]. however, researchers have found anomalies in the form of ground-glass opacities in the chest ct scans of covid-19 patients [14]. research has demonstrated that developing a system using chest ct imaging can diagnose and quantify covid-19 cases [15]. however, x-ray images can be used instead of ct scans to detect covid-19. x-rays can be obtained without the enhanced danger of propelling the pathogen through the air. the x-rays may help sort out the patients into the highest risk group, high-risk group, and low-risk group for the rest of the complications, apart from helping in assessing the severity of disease on one or more occasions. nevertheless, compared with x-ray imaging, ct imaging is significantly more time consuming and necessitates a rigorous sanitation process before patients can be switched. even so, high-quality ct scanners may not be readily accessible, so a timely chance to screen for viral pneumonia may not exist. therefore, covid-19 medical imaging and diagnostics are important for the fast diagnosis of covid-19 [16]. medical images such as x-ray images can be analysed to provide relatively immediate diagnostic information by identifying potential patterns that can result in the automatic diagnosis of the disease. the chest x-ray (cxr) is the most frequently used imaging modality in the diagnostic examination of patients with thoracic abnormalities. the reason is its rapid imaging speed, low radiation, and low cost [17]. expert radiologists frequently perform interpretation without assistance in emergency and hospital settings, where it is universally available. indeed, the covid-19 pandemic is characterised by a rapid spread rate, and rt-pcr is the standard diagnostic procedure for viral nucleic acid detection [18, 19]. nevertheless, this test has suboptimal sensitivity and specificity. numerous hyperendemic regions and countries are also unable to provide adequate rt-pcr testing for tens of thousands of suspected subjects within a brief period. additionally, concerns exist regarding the discomfort associated with rt-pcr, the absence of swabs, the necessity of reagents, delays in the production of results, and substantial false-negative noor kamal al-qazzaz al-khwarizmi engineering journal, vol. 21, no.1, pp. 1327 (2025) 15 rates. these concerns warrant the investigation of alternative diagnostic methods [12]. for the purpose of rigorous detection, contact tracing, and isolation of infected subjects during the primary stage of infection, all such methods must be precise, rapid, and effective instruments for detecting covid-19 infection. in this research, efforts were exerted to implement efficient network architectures and transfer learning techniques; thus, mobilenetv2 was used as a computational tool to autonomously predict the presence of covid-19 based on cxr images. the most comprehensive collection of cxr pictures ever assembled for classification was utilised. these images included healthy individuals, covid-19 patients, and patients with other lung illnesses. the performance of the mobilenetv2 is best suited for applications that deal with real-time processing and classification of covid-19, noncovid-19 lung opacity, and normal control. given that it is comparatively lightweight, it carries out inference in a short time, which is essential in a mobile application where response time can influence a clinician’s decision. furthermore, the model uses depthwise convolutions and thus operates with a considerably smaller number of parameters than typical convolutional networks. this enables deployment on devices with low computational capability and makes the app fast as well. additionally, mobilenetv2 has a built-in library, and a user can start with prior knowledge from large datasets. this capability enhances the model’s performance, especially when there is little data available because covid-19 detection may be specific in some instances. mobilenetv2 can also be scaled up easily owing to the optimised architecture. the size of the models can be easily scaled up or down depending on the available processing power; and hence, they can be conveniently used across the broad range of devices that exist in the mobile platforms. lastly, the outcomes achieved based on mobilenetv2 can be compared with other deep-learning architectures that are extensively used in medical image analysis, including resnet, densenet, and inception [20,21]. conversely, resnet can handle very deep networks with relative ease by virtue of the residual connections. however, it is slightly slower and may not be as efficient when used on a mobile device. meanwhile, mobilenetv2 is designed to perform adequately for mobile platforms not necessarily high performing. densenet includes the use of feature reuse because the gradients can flow freely during the training process. nevertheless, owing to its heavy information-processing functionality, memory usage can also be enhanced. mobilenetv2 follows a less complex architecture to be more portable on mobile devices. inception models are accepted to be designed for multi-scale feature extraction on the given images, but they are often costly in terms of computation. mobilenetv2 has similar efficiency in feature extraction owing to its more simplistic architecture making it more preferable for real-time use. thus, despite the plethora of models available, for our research, we opted for mobilenetv2 owing to its efficiency, small number of parameters, ability to use transfer learning, and scalability. thus, when comparing it to other architectures, we want to emphasise the benefits of the proposed architecture for the context of mobile applications for medical image analysis. to further improve the depth and practicality of the article, we integrate this comparative discussion for increased coverage of depth and practicality for the users, as well as clinical decision making [22,23]. the present study aimed to enhance the capacities of medical practitioners by leveraging cnn. covid-19 diagnosis was improved through radiographic image analysis, making a significant contribution to the development of a mobile application that promptly detected covid-19, thereby saving medical professionals time and resources and facilitating timely preventative actions. moreover, this work explored the possibility of integrating matlab with the telegram messaging platform by developing a telegram bot that can communicate with matlab to conduct intricate computations. additionally, it performed detailed analyses, thereby improving user experience and accessibility. collectively, the purpose of these contributions was to enhance the application of ai in medical diagnostics. therefore, in the context of covid-19, these contributions offered highly dependable, user friendly, and efficient tools for early detection and analysis. furthermore, the objective of this research was to provide a comprehensive examination of cnn's use in the analysis of radiographic visual images. this can enhance the ability of seasoned medical practitioners and researchers to develop models relevant to the covid-19 domain. applying the deep mobilenetv2 cnn model is less time consuming than pcr with delays caused by machine availability or the challenges faced by clinicians when extracting details from ct scans of large dimensions. thus, deep-learning-based mobile applications have a positive impact on healthcare delivery and may also aid in the early detection of covid-19. the utilisation of the mobilenetv2 model and transfer learning techniques to construct a noor kamal al-qazzaz al-khwarizmi engineering journal, vol. 21, no.1, pp. 1327 (2025) 16 computational tool within this manuscript clearly articulates the contributions of the paper. this tool aims to autonomously predict the presence or absence of radiological indications consistent with covid-19 in patients based on analysis of cxr images. the authors make these contributions to the best of their knowledge. moreover, this dataset represents the most extensive collection of cxr images ever compiled and used for classification. the dataset comprises covid-19 patients, noncovid lung-opacity illnesses, and healthy-control individuals. 2. related works ai, particularly deep learning, is applicable for the automatic diagnosis of various diseases in the human body [20–21]. deep learning is applied as a feature extractor that improves classification choices based on reported classification accuracies [22]. despite the fact that chest radiology imaging systems are commonly found in hospitals and can be performed quickly, the interpretation of radiography images by radiologists remains a significant concern owing to the human capacity to detect the subtle visual features present in the images. the field of image analysis and processing in the biomedical field has seen very spectacular results. deep-learning algorithms and cnn models have recently been utilised. several studies have been performed utilising deep-learning approaches to automate the diagnosis of covid-19. the majority of deep-learning-based models are hierarchical, with each layer extracting information unique to covid-19 that may be used to distinguish covid19 photos from other kinds of images. the most popular learning technique that can effectively interpret images and videos, across a range of computer vision applications [23, 24]. in recent years, numerous have been published about the diagnosis of covid-19 from x-ray images of lungs with the help of various ai tools. new approaches to fine tuning using transfer learning approaches, different network architectures, and ensemble techniques were applied to enhance the network performances and thus distinguish covid-19 from normal lung and other lung diseases. nevertheless, the results obtained are optimistic because the developed deeplearning models can be built based on a small dataset for covid-19 detection. khan et al. [25] compared a limited number of machine-learning algorithms specifically for a four-class classification problem with the dataset used in the current study: covid-19, bacterial pneumonia, viral pneumonia, and normal. through the resnet50 classifier developed by goldstein et al. [26], the accuracy and sensitivity for detecting covid-19 is 89.7% and 87.1%, respectively. for instance, wang and wong integrated about 14k cxr images but only achieved an 83.5% accuracy rate by using a deep cnn referred to as covidnet. moreover, motamed et al. [27] introduced a generalisation of the above idea called randomised generative adversarial network, which is capable of identifying images of an unseen class (covid-19) from specified and labelled classes (normal and viral pneumonia) without requiring any labels and training data of the novel class (covid-19), achieving an accuracy rate of 0.77 auc. when comparing the results of utilising the described approaches separately, their combination enabled higher levels of covid-19 detection to be attained. therefore, many studies have used deeplearning techniques to examine different datasets containing lung images from covid-19 patients healthy individuals and those with non-covid pulmonary diseases. for instance, saeed et al. evaluated the performance of deep-learning models, with particularly focus on vggnet, googlenet, and resnet. these models are used to process xray and ct-scan images of covid-19 patients' lungs [28]. moreover, alwawi et al. have introduced a deep-learning-based model for expanding and detecting covid-19 cases by using x-ray images. the model comprises a cnn architecture in which the network was trained to classify images into positive or negative covid-19 [29]. other studies have proposed a deep-learning approach by using cnn for binary x-ray images for covid-19 classification in which the dataset of x-ray images is trained to diagnose covid-19 as positive or negative [30]. moreover, deep learning has become a prominent topic in computing and is extensively applied in medical applications. it proves effective for the automatic diagnosis of covid-19. another research has implemented a cnn model with fewer layers and optimised parameters to obtain an implementation resulting in reduced training time for the binary classification of covid-19 using by x-ray images [31]. khaleel et al. [32,39] focused on training vgg cnn models such as vgg16 and vgg19 using xray images to identify covid-19. zahra et al. [33] have suggested a covid-19 prediction infrastructure that makes use of deep learning with a cnn model to identify the presence of covid19. researchers suggested a two-step transformer model for covid-19 detection [34] using pretrained cnn models, including inceptionv3 and noor kamal al-qazzaz al-khwarizmi engineering journal, vol. 21, no.1, pp. 1327 (2025) 17 efficient net. al-qazzaz et al. have used automatic deep cnn model to detect covid-19 [40]. this work introduced a cnn model to identify covid-19 infections from cxr images. we aimed to use a distinctive cnn model to automate the identification of covid-19 through the utilisation of cxr images with a dataset of three groups containing more than 18000 x-ray images. our study evaluated the efficacy of mobilenetv2 models to improve model generalisation and prevent overfitting. comprehensive evaluations were performed using training–validation–testing, and results demonstrated high effectiveness. 3. methodology figure 1 presents an overview of the primary phases used in this investigation. the academic process began with the acquisition of cxr pictures, followed by a preprocessing step. subsequently, cnns were used to analyse the images. finally, the classification stage was executed to categorise the x-ray findings. fig. 1. work block diagram 3.1. dataset this study aimed to create a new huge dataset on the coronavirus family by combining different cxr datasets that are freely accessible to the public. three categories make up the combined dataset. these categories include lung masks and the x-ray dataset (covqu), which is the largest freely available covid positive database. this study included 18,479 cxr pictures, amongst which 8851 were normal, 6012 were non-covid lung infections, and 3616 were covid-19 cxr images, together with their accompanying ground-truth lung masks (figure 2). fig. 2. chest x-ray images. chest x-ray images preprocessing • resizing of data and converting its to rgb images . convolutional neural networks (cnns) •mobilenetv2 smartphone application noor kamal al-qazzaz al-khwarizmi engineering journal, vol. 21, no.1, pp. 1327 (2025) 18 3.2. preprocessing preprocessing x-ray data is an important step in preparing the data for use in neural network models, such as mobilenetv2. one possible preprocessing technique that has been used in some studies is resizing the x-ray images to rgb images so that they can be used in mobilenetv2. this neural network architecture is designed to work with rgb images. the x-ray pictures were initially greyscale. to obtain the rgb input, the greyscale values were copied three times for the red, green, and blue channels. the outcome was an rgb image where all the three bands had the same values, so the integrity of the intensity was maintained with an addition of image format into rgb format after converting the images into rgb format, the quantitative value of images of different sizes were interpolated into 224×224 pixels by using bilinear technique. this step ensured that the dimensions of the images, or at least their aspect ratios, remained intact to reduce the chances of the model receiving images of an undesired size. it also retained the images qualifying for the mobilenetv2 model’s input size. the data were divided into training/validation and testing sets at a ratio of 70:30. the training/validation set was divided into training and validation sets at a ratio of 70:30. the models were built by the training set and assessed with the validation set to measure the performances of the models in terms of accuracy and then tested by the testing set to measure again and confirm the accuracy. 3.3. mobilenet-v2 mobilenetv2 is a mobile-oriented architecture exhibiting reduced complexity and size owing to its utilisation of depth-wise separable convolution. this design choice renders it well-suited for execution on devices possessing limited processing capabilities. the mobilenetv2 architecture extended the feature-extraction capabilities and incorporated a novel inverted residual structure. the model architecture comprises a convolutional layer followed by a succession of residual bottleneck layers. the kernel size for all spatial convolution operations is determined while utilising relu6 as the non-linearity function, in conjunction with batch normalisation and dropout techniques during the training phase. the bottleneck block has three layers: an initial (1 × 1) convolutional layer, a subsequent (3 × 3) depth-wise convolution layer stated above, and a final (1 × 1) convolutional layer without relu6 activation [27]. the mobilenetv2 model is currently widely utilised because of its exceptional ability to extract features and its compact size [37]. the mobilenet-v2 model is a pre-trained model that has been developed specifically for the purpose of picture categorisation, as shown in figure 3. pre-trained models refer to deep neural networks that have undergone training using a substantial dataset of images. by utilising pre-trained models, developers are able to avoid the necessity for constructing and training neural networks from the ground up, resulting in time savings throughout the development process. fig. 3. mobilenetv2 architecture mobilenetv2 expects images of 224 × 224 pixels with three colour channels. in other words, it expects an input of shape (224, 224, 3). you can pass multiple images at once to the model. this means that the input should actually consist of four dimensions, where the first dimension corresponds with the index of the image [27]. the output of mobilenetv2 is a probability distribution over a set of predefined classes. the number of output classes depends on the specific task for which the network was trained. if the model is designed to classify, for example, 1000 classes, then the output vector should have 1000 values, where each value represents its input image probability for a specific class [34]. thus, the highest probability value is referred to the predicted class [37]. in summary, classification can be defined as the process of categorising observations for which the corresponding category has been determined using the knowledge obtained from a dataset. lastly, the mobilenetv2 model was modified by reducing the number of classes from 1000 to 3 in this research to classify the x-ray dataset into three classes; normal, ling opacity, and covid-19. this noor kamal al-qazzaz al-khwarizmi engineering journal, vol. 21, no.1, pp. 1327 (2025) 19 deep-learning model is popular and widely used, primarily in mobile and resource-constrained environments. owing to its effective design (i.e., speed and accuracy on mobile devices), it is recommended as a perfect choice to develop a mobile application for diagnosing lung diseases like covid-19 [36]. 3.4. mobile display the progress in various technologies is massive. these technologies include integration with message platforms to improve the conventional access of the user interface to powerful computational capabilities. specifically, this work introduced the integration of telegram application (a popular messaging platform) with matlab software (an extensively used computational tool) by developing a telegram bot. the main objective of this integration was to leverage data-processing capabilities and robust matlab algorithms to offer users with interactive and unified experience while executing complex analyses and computations. several advantages were provided by this integration. firstly, the integration of matlab and telegram enabled users to interact with matlab functionality in the familiar messaging environment. the telegram bot incorporated the matlab toolbox and extensive algorithm library to perform a wide range of statistics such as visualisation, machine learning, and data analysis secondly, users who may not have experience or access to matlab can be a complex mathematical accessible and used just man. thirdly, telegram can provide a multi-purpose medium for sharing and communicating results. for example, users can easily add images, statistics, and other relevant information to the telegram bot, which allows them to integrate seamlessly with matlab algorithms to use data sources, and images with all calculated results. the bot can then respond directly through the telegram interface. finally, the need to switch between different interfaces or applications to perform mathematical tasks was eliminated, thereby enhancing the user experience. the essential steps of our process of integrating matlab with a telegram bot was explained in detail. hosting the integrated system, connecting matlab to the telegram platform, developing the matlab code to handle user interactions, utilising the matlab telegram bot toolbox, and setting up the telegram bot are the essential steps. we also explored the benefits, challenges, and potential applications of this integration, as well as provided examples and demonstrations to illustrate its functionality. however, the first step was the creation of a bot account and obtaining an api token for authenticating and communicating with the bot. a special bot called botfather was the easiest way to create the telegram bot. 3.4.1. python–telegram-bot library a python wrapper for the telegram bot api is the python–telegram-bot library. it offers a simple and suitable interface to interact with the telegram bot api and enables developers to create telegram bots using python. conversely, the telegram bot api contains a collection of interfaces and techniques offered by telegram to develop bots. these bots are exclusive telegram accounts for interacting with users and automated tasks. by providing high-level classes and functions and then abstracting the underlying api details, this library simplifies the process of developing telegram bots. moreover, it provides an event-driven architecture for handling updates and user interactions. it also handled the communication with the telegram bot api. we developed a python code that interacted matlab with telegram and can communicate with the telegram bot api, perform computations, processes command, and handle user interactions. this code set up the telegram bot using the python– telegram-bot library and the telegram bot api. meanwhile, users can run a matlab script and send an image through the bot. the code overview is as follows:  importing required modules: a module in python language is defined as a file that involved the python code (incorporating variables, functions, and classes). other python programmes can use it. the module is required to interact with the telegram bot api and to perform other operations.  configuring the bot: as mentioned earlier, the botfather function creates the telegram bot token, which is then assigned to the token variable. this token is required for authenticating and communicating the script with the telegram bot api.  handler functions: the handler for the /start command is the start (update: update, context: callbackcontext) function, which is triggered when the user sends the /start command to the bot. this function sends a welcome message to the user with the keyboard and creates a static keyboard with two buttons: ‘run matlab script’ and ‘send a picture’. noor kamal al-qazzaz al-khwarizmi engineering journal, vol. 21, no.1, pp. 1327 (2025) 20 the handler for the ‘run matlab script’ action is the test (update: update, context: callbackcontext) function, which is triggered when the user clicks the ‘run matlab script’ button. this function runs a matlab command and sends a reply to the user, indicating that the matlab script is being executed. the handler for the ‘send a picture’ action is the save picture (update: update, context: callbackcontext) function, which is triggered when the user sends a picture to the bot. this function checks if the 'images' folder exists or not. if no such folder exists, this function creates one. if the folder already exists, it removes its contents and creates a new folder. then, it retrieves the highest resolution photo from the received photos array, downloads the photo as a byte array, and saves it with the filename set as the user's chat id. the text_handler (update: update, context: callbackcontext) function handles text messages received when the user clicks the buttons. if the received text message is ‘send a picture’, it sends a reply asking the user to send a picture. if the message is ‘run matlab script’, it calls the test () function.  running the bot: the main () function is called when the script is executed, initiating the setup and execution of the telegram bot. in the flowchart, the steps of programming code are presented. when the user sends /starts, the start function is run and by that, and then the bot sends a message welcoming the user. the user should choose an action from the handlers. if the user chooses to send a picture handler, the bot gives him excess to the pictures gallery to pick a picture, and then the programme receives the picture and saves it in the image folder. the run matlab script handler sends a message to the programme to run the function of running the matlab code. 3.4.2. performance measure the validation curve helped evaluate the model's performance on unseen data during training. it measured the validation accuracy and loss, computed on a separate dataset called the validation set. the validation set contained examples that the model had not seen during training, allowing us to estimate its ability to generalise to new, unseen data. the validation accuracy represented the model's performance on the validation set, whereas the validation loss reflects the discrepancy between 27 predicted and actual values for the validation data. monitoring the validation curve was critical to identifying overfitting or underfitting. the suggested network was trained with 50 epochs using mobilenetv2 and 2400 iterations with 48 iterations per epoch and 3 rounds of validation. after several epochs without validation accuracy increase, training was ended. developers and academics can evaluate the deep-learning framework and mobile app for covid-19 identification from cxr pictures by using these performance measures. the quantitative findings were promising and demonstrated the success of the suggested strategy, but the qualitative outcomes must be examined. any segmentation technique should be compared against hand delineations to determine qualitative performance. manual delineations needed domain expertise, making them difficult. it is complex and time consuming, so the manual ground-truth segmentation for the covid-19 picture collection was tough to achieve. however, segmented results may be visually examined to assess performance. the suggested method segmented the x-ray image areas well. the extensive qualitative and quantitative research showed that the suggested technique outperformed most current approaches. the suggested strategy produced better segmented results than current methods, helping clinicians analyse suspected patients non-invasively. this technique can help undertake large testing with realistic segmented outputs to inhibit covid-19's rapid spread. image types may respond differently to a given technique [37]. the suggested system was assessed using average classification accuracy and confusion matrix. 4. results 4.1. results of performance measures accuracy or performance metrics are crucial measures for evaluating the effectiveness and reliability of a trained neural network, performance metrics provide quantitative measures that quantify how well a neural network performs on specific tasks such as classification and object detection. these metrics serve as benchmarks for evaluating the quality of predictions made by the network and help in comparing different models or algorithms. one of the most fundamental performance metrics is accuracy, which measures the proportion of correct predictions made by the neural network over a given dataset. a notable deep-learning framework, mobilenetv2, was used in this work to develop a system with an average classification accuracy of 90.6% for covid-19 detection. noor kamal al-qazzaz al-khwarizmi engineering journal, vol. 21, no.1, pp. 1327 (2025) 21 fig. 4. process of training the mobilenetv2 the proportion of accurate classifications produced by the moiblenetv2 network is depicted in figure 4. it shows normal, non-covid lung opacity, and 983, 1720, and 196 of covid-19, respectively. additionally, covid-19 was accurately identified with a non-covid lung opacity of case 61 and a normal lung opacity of case 14, respectively. a total of 101 lung opacities were erroneously categorised as normal, whereas 90 noncovid lung opacities were erroneously classified as covid-19. moreover, normal are accurately categorised with 12 and 23 are mistakenly labelled as covid-19 and non-covid lung opacity patients, respectively. the test was conducted by saving an x-ray image on the computer and then importing the image into matlab. afterwards, we processed the image, such as resizing it to fit the network. preprocessing was applied to the image based on matlab code, and then the specific test code was applied to display the results within seconds. fig. 5. confusion matrix for normal subjects, lung opacity, and covid-19 patients by using mobilenetv2. table 1 presents key performance metrics of the mobilenetv2 deep-learning model for detecting covid-19 from cxr images, categorised into three classes: covid-19, lung opacity, normal images. the analyses of precision levels showed that the developed model had high accuracy in defining true positive cases of disease detection with covid-19 precision level reaching 92.91%. this finding indicated that the model reduced false positives, which is useful in the clinical context to reduce anxiety and further testing in patients. the sensitivity, which showed the accuracy percentage of the proposed model for positive samples as covid-19, was 90.6%. thus, although the model worked, it did not catch every single case of covid-19, which may leave some false negatives. this performance was crucial to eventual early detection, particularly in a pandemic setting that positively reacted to the timely identification of cases and subsequent containment. therefore, the model specificity, which was 96.45% for covid-19, showed that normal cases are well differentiated from actual covid-19 cases while reducing on the cases of false positives, where otherwise healthy people were incorrectly diagnosed. this is more so at a time that patients and healthcare providers needed to have confidence in diagnostic technologies. the calculated accuracy of the model was 90.59%, indicating that the model produced almost accurate universal results for all classes. the fmeasure of 91.74%, which was obtained in identification of covid-19 compels the effectiveness of the proposed model as it combines both the precision and the recall. applying this model to a mobile application improved patient access to care because diagnoses can be made rapidly using the app without requiring noor kamal al-qazzaz al-khwarizmi engineering journal, vol. 21, no.1, pp. 1327 (2025) 22 complex laboratory support. regarding the work’s implementation of the model, the authors pointed out in the abstract that the model supported quicker diagnosis and also reduced the pressure on healthcare facilities, indicating its usefulness in combating covid-19. table 1, performance metrics of mobilenetv2 for covid-19 detection from cxr images. 4.2 results of testing the network the test was conducted by saving an x-ray image on the computer and then importing the image into matlab (figures 6, 7 and 8). afterwards, we processed the image, such as resizing it to fit the network. the image was preprocessed based on matlab code, and then the specific test code was applied to display the results within seconds. fig. 6. result of covid-19 cxr test. fig. 7. result of normal cxr test fig. 8 result of pneumonia bacterial cxr test masseurs covid-19 (%) lung opacity (%) normal precision 92.91 90.01 84.85 sensitivity 90.6 95.34 63.02 specificity 96.45 86.32 98.79 accuracy 90.59 90.59 90.59 f-measure 91.74 92.6 72.32 noor kamal al-qazzaz al-khwarizmi engineering journal, vol. 21, no.1, pp. 1327 (2025) 23 4.3 mobile-display results the test was conducted by accessing the telegram bot and clicking on ‘start’. then, a welcoming message appeared, and the desired cxr image for testing can be sent. a message was received from the bot confirming that the image had been received. the phrase ‘run matlab script’ was typed to automatically execute the test code in matlab. the test result was sent as a text message in the bot within a few seconds. fig. 9. mobile-display results of three different cxr cases through covid-19 diagnosis from cxr by using deep-learning algorithms via a mobile application, we focused on the acquisition and preprocessing of the dataset. the list had three categories: copd, normal, and lung opacity. we firstly collected a set of cxr images superimposed by the categories. data collection played an important role in training our deep-learning model to accurately classify x-ray images. secondly, after obtaining the dataset, we performed preprocessing steps to ensure that our chosen deeplearning model was compatible with mobilenetv2. the acquired x-ray images were initially greyscale. however, given that mobilenetv2 was designed to work with rgb images, we had to convert greyscale images into rgb format. these changes allowed us to use the full capabilities of the mobilenetv2 framework for our distribution project. 5. conclusion covid-19 infection is likely to cause persistent lung damage, which can lead to death. this study aimed to classify cxr images into covid-19, non-covid-19 lung opacity, and normal control. covid-19 detection was conducted utilising mobilenetv2 deep-learning models because it was critical to detect covid-19, which spreads rapidly and internationally. numerous researchers have used ai-based xray image processing to detect covid-19. various approaches, new network designs, and ensemble solutions were proposed for improving covid-19, normal, and other lung-disease classification. goldstein et al. [26] identified covid-19 by using a pre-trained deep-learning network (resnet50) that achieved 89.7% accuracy and 87.1% sensitivity. wang and wong [38] achieved 83.5% accuracy by using covid-net, a deep cnn. noor kamal al-qazzaz al-khwarizmi engineering journal, vol. 21, no.1, pp. 1327 (2025) 24 furthermore, motamed et al. [27] suggested a randomised generative adversarial network that detected covid-19 images from known and labelled classes (normal and viral pneumonia) without labels or training data from the unknown class, with an auc of 0.77. one of the innovative characteristics of the proposed approach was subjecting the photographs to preprocessing. preprocessing procedures can extract more features efficiently from image data. the stacking approach involved superimposing each pixel of equivalent images and increasing the pixels with low efficiency. the proposed technique resulted in the development of an efficient mobile application for covid-19 detection based on the mobilenetv2 model. the model was designed to provide faster and more accurate results. we also illustrated the applicability of our approach to smart mobile devices with the mobilenetv2 model, which can be examined on mobile devices without the use of any hospital devices. in conclusion, our covid-19 detection method outperformed those reported in recent literature for covid-19 and other lung infection detection. the classification of covid-19 data, opacity lung disease, and normal pictures yielded a precision of 92.91%, sensitivity of 90.6, and specificity of 96.45%, accuracy of 90.6%, and f-measure of 91.74% for covid-19 detection. a detailed investigation of cxr image-enhancement techniques for covid-19 detection was provided, and the results were reliable and generalisable because training and validation were conducted on a large dataset. this study had certain limitations. firstly, we included a large dataset of over 18000 images, but it may not fully represent covid-19 populations worldwide, including age, gender, ethnicity, and comorbidities. the model may not be generalisable across demographic groups. secondly, the quality of cxr pictures can also vary depending on the imaging device, patient posture, and artifacts, which can affect model accuracy. in real-world applications, this variability may influence model resilience. thirdly, this study focused on immediate detection. thus, future work should evaluate the model's potential to detect long-term covid-19 lung injury. in future investigations, deep-learning-based analyses will be performed utilising data images of other organs impacted by the virus according to covid-19 experts. we intend to develop a future approach using various organising strategies to improve the datasets. as data on the factors influencing the virus in human chemistry (e.g., blood group, rna sequencing, age, gender, etc.) become accessible, we will conduct a solutionoriented study with ai. overall, our research showed that x-ray devices can depict pictorially which portions of input data such as images shaped the outcomes of the model. this can help various individuals understand why the model arrived at the given results. even after applying preprocessing to lessen its impact on the final decision, the significance of mobilenet features became evident. it can help doctors determine how accurate the model’s outputs are or how reliable the software is. in this scenario, the application interface's final visualisation tools for determining the final choice based on the models is enhanced. the beneficial effects include safety and non-invasiveness for users, as well as improved decision making for doctors by providing statements with more background information. all these factors indicate the high potential of our app for testing and as an easily available, open platform for the doctors. references [1] hussain, e., hasan, m., rahman, m.a., lee, i., tamanna, t. and parvez, m.z., 2021. corodet: a deep learning based classification for covid-19 detection using cxr images. chaos, solitons & fractals, 142, p.110495. 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"automatic covid-19 detection from chest x-ray using deep mobilenet convolutional neural network." 2024 46th annual international conference of the ieee engineering in medicine and biology society (embc). ieee, 2024. https://doi.org/10.1016/j.bspc.2021.102800 (2025) 13-27، صفحة 1، العدد21مجلة الخوارزمي الهندسية المجلد نور كمال القزاز 27 األشعة السينية للصدر باستخدام إطار عمل التعلم العميق عبر من covid-19اكتشاف تطبيق الهاتف المحمول ،4، مسرة محمد مهدي 3، تبارك عماد حسين2، االء عبد المنعم الدوري*1نور كمال القزاز 6سيتي أنوم أحمد ،5 شوال حميد بن محمد علي ، جامعة بغداد، بغداد ، العراق الخوارزمي الهندسة ، كليةهندسة الطب الحياتيقسم ،13،2،4 .سيالنغور، ماليزيا قسم الهندسة الكهربائية واإللكترونية والنظم، كلية الهندسة والبيئة المبنية، جامعة كيبانغسان ماليزيا، 5 النظم، جامعة كيبانغسان، ماليزيا، سيالنغور، ماليزيامركز الهندسة اإللكترونية وهندسة االتصاالت المتقدمة، قسم الهندسة الكهربائية واإللكترونية وهندسة قسم الهندسة الكهربائية واإللكترونية، كلية الهندسة، جامعة بوترا ماليزيا، سيالنغور، ماليزيا6 المعهد الماليزي لبحوث الشيخوخة، جامعة بوترا ماليزيا، سيردانغ، سيالنغور، ماليزيا noorbme@kecbu.uobaghdad.edu.iq*البريد االلكتروني: المستخلص اصابةبالتهاب رئوي حاد، مما يؤدي عادةً إلى الوفاة. أظهرت البيانات اإلشعاعية أن المرض ينطوي على 19-يصاب المرضى المصابون بفيروس كوفيد من خالل تحليل covid-19الرئة الخاللي، وعتامة الرئة، وعتامة الزجاج األرضي الثنائية، والعتامة غير المكتملة. تهدف هذه الدراسة إلى تحسين تشخيص بكفاءة، ويوفر على covid-19(، مما يساهم بشكل كبير في تطوير تطبيق الهاتف المحمول الذي يحدد cxrصور األشعة السينية للصدر اإلشعاعي ) العصبية cnn شبكة مع صور الرئة cxr 1800المهنيين الطبيين الوقت والموارد ويسمح بالتدخالت الوقائية في الوقت المناسب باستخدام أكثر من mobilenetv2 يتم تقييم أداء نموذج التعلم العميق .mobilenetv2 س باستخدام الدقة والحساسية والخصوصية والدقة وقياf لتصنيف صورcxr إلى covid-19 وعتامة الرئة غير ،covid-19 90.6٪، ودقة 96.45، وخصوصية 90.6٪، وحساسية 92.91، والطبيعي. أظهرت نتائج هذه الدراسة دقة ،٪ التصنيف من خالل تحسين أداء mobilenetv2المقترح للتعلم العميق cnn. في الواقع، يمكن لنموذج covid-19في اكتشاف f 91.74٪ومقياس تقليل الوقت المطلوب لجمع نتائج كل صورة لتطبيق الهاتف المحمول. mailto:noorbme@kecbu.uobaghdad.edu.iq 3.4.1. python–telegram-bot library a python wrapper for the telegram bot api is the python–telegram-bot library. it offers a simple and suitable interface to interact with the telegram bot api and enables developers to create telegram bots using python. conversely, the telegram bot api... we developed a python code that interacted matlab with telegram and can communicate with the telegram bot api, perform computations, processes command, and handle user interactions. this code set up the telegram bot using the python–telegram-bot libra... 3.4.2. performance measure <4d6963726f736f667420576f7264202d20c7d3e3c7c120e6cce3c7e120e6cf20c7d3c7e3c9312d3132> this is an open access article under the cc by license : al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 18, no. 2, june, (2022) p. p. 112 estimate and analysis the availability of generator in electric power plant using ann asmaa j. awad* ahmed a. ahmed** osamah f. abdulateef *** *,***department of automated manufacturing engineering/al-khwarizmi college of engineering/ university of baghdad, al-jadriayh / baghdad/iraq **department of mechanical engineering/ university of baghdad/ al-jadriayh/baghdad/ iraq *email: asmaa_jamal_1992@yahoo.com **email: aa.alkhafaji@yahoo.com ***email: drosamah@kecbu.uobaghdad.edu.iq (received 27 december 2021; accepted 20 april 2022) https://doi.org/10.22153/kej.2022.04.001 abstract the large number of failure in electrical power plant leads to the sudden stopping of work. in some cases, the necessary reserve materials are not available for maintenance which leads to interrupt of power generation in the electrical power plant unit. the present study, deals with the determination of availability aspects of generator in unit 5 of al-dourra electric power plant. in order to evaluate this generator's availability performance, a wide range of studies have been conducted to gather accurate information at the level of detail considered suitable to achieve the availability analysis aim. the weibull distribution is used to perform the reliability analysis via minitab 17, and artificial neural networks (anns) by approaching of feed-forward, back-propagation. operating data from the years 2015–2017 were used to calculate the availability by traditional method (weibull distribution) and train the anns, while data from the year 2018 of operation were used to verify the model. the study implies that the ann may be able to forecast the availability of the generator with a correlation coefficient (r) 0.99874 and a mean square error (mse) 5.6937e-06 between the availability predicted by ann and weibull distribution output. keywords: back-propagation, failure analysis, feed-forward, weibull distribution. 1. introduction estimation theory is a field of statistics concerned with estimating parameter values based on empirical data containing a random component that has been measured. the parameters represent an underlying physical setup in such a way that the distribution of the measured data is affected by their value [1].the maintenance besides repairs are the problems that cost a large part of the budget, the high costs occur because of parts failure, therefore by improving the availability and reliability that will lead to decrease costs, in order reducing system maintenance. in this sense, availability, which is a combination of maintainability and dependability, has become widely employed as a metric for determining the success of a system's maintenance. availability is defined as the chance that the system will operate properly under specified conditions at any point in time, or as the ratio of uptime to total time, while the reliability concept is the probability that the item may work to fulfill a certain work for a span of time until the breakdown has occurred, so the behavior of the complex repairable systems can be studied in terms of their availability [2]. availability analysis techniques have been gradually accepted as standard tools for the planning and operation of complex thermal power plants. de oliveira, et al, [3] presented a monte carlo simulation to project the availability of hydroelectric plants. the proposed methodology asmaa j. awad al-khwarizmi engineering journal, vol. 18, no. 2, p.p. 112(2022) 2 addresses operational and regulatory aspects, where the plant’s availability is evaluated through the measured hours of interruptions due to scheduled and forced maintenance. the proposed model was successfully implemented using real data, achieving the goal of estimating the risk of regulatory penalties for the hydroelectric plant. in addition, the proposed methodology is applicable to other hydroelectric power plants. hanumant jagtap, et al, [4] presents availability based simulation modeling of the boiler–furnace system of thermal power plant with capacity (500mw). the markov based simulation model of the system is developed for performance analysis. the differential equations are derived from a transition diagram representing various states with full working capacity, reduced capacity, and failed state. the availability of the boiler–furnace system is optimized using particle swarm optimization method by varying the number of particles. the study results revealed that the maximum system availability level of 99.9845% is obtained. in addition, the optimized failure rate and repair rate parameters of the subsystem are used for suggesting an appropriate maintenance strategy for the boiler–furnace system of the plant. zouhair issa ahmed, et al, [5] suggested a methodology for availability estimation of the caustic pump by using artificial neural network (ann), training pairs (time, availability), to determine availability at every ten working hours, for the real times of failures matlab codes were used, by front feed type of multilayer type of network for each parts for the caustic pump study. the proposed method was more precise and closer to reality, the mode and steps of the methodology in predicting by using anns, enables its implication on any part and equipment for mechanical or electrical system. hanumant p. jagtap, [6] presented reliability, availability, and maintainability (ram) analysis framework for assessing the achievement of a circulation system of water (wcs) used in a coal-fired power plant (cfpp). the achievement of wcs is estimated utilizing a reliability block diagram (rbd), fault tree analysis (fta), and markov birth–death probabilistic approach. the system under consideration composed of five subsystems connected in series and parallel structure. the reliability block diagram (rbd) and fault tree approach (fta) have been used for the achievement evaluation of wcs. the availability of the system was optimized utilizing the particle swarm optimization method. the optimized failure rate and repair rate parameters of the subsystem are utilized to proposed an acceptable maintenance strategy for the water circulation system of the thermal power plant. ling wang, et al, [7] developed an improved delay time model (dtm) with imperfect maintenance at inspection on the basis of the assumption of imperfect inspection maintenance and perfect failure maintenance. the model of the long-run availability for the improved dtm is fixed. numerical simulations are done to study the effect of imperfect maintenance on the long-run availability and to verify the credibility of the parameters estimation method. the results revealed that imperfect maintenance reduces the long-run availability. p.s. rajpal, et al, [8] utilized neural network approach to analyze the reliability, availability and maintainability of a complex repairable system a helicopter transportation facility, the operational characteristics of the helicopter facility have been discovered, measured, visually shown and modeled using recent past data of the system. the insights received from outcomes of simulation are important in designing strategies for optimal operation of the system. manmath kumar bhuyan ,et al, [9] presented a novel technique for software reliability estimation utilizing feed forward neural network with back-propagation. most of the predictive criteria are considered. an experimental evidence showed that feed forward network with back propagation yields accurate result corresponding to other methods, and that this approach is computationally practicable and can considerably decrease the cost of testing the software by estimating software reliability. małgorzata kutyłowska [10], predicted the availability indicator of water mains, distribution pipes, and house connections by means of an ann model. operating data for a period 1999– 2005 were utilized to train the anns while data from the next seven years of operation were utilized to prove the model. thus anns are fairly simple to carry out and utilize when functions of many variables are to be approximated. the aim of this study is to construct a model by artificial neural network methods to estimate the availability of the generator in unit 5 of al dora electric power plant. 2. case description aldoura power station shown in figure 1 is electric steam-powered station located in baghdad near the tigris river. it consists six units working to generate electricity for the capital baghdad with a production capacity estimated at (400mw) asmaa j. awad al-khwarizmi engineering journal, vol. 18, no. 2, p.p. 112(2022) 3 per unit and all unit connected by parallel to compensation in the event of a malfunction in any of the units to perform the required function and increase efficiency, unit 5 was taken for the purpose of the study. fig. 1. aldoura power station. unit 5 consists of four main subsystems linked together in series; these subsystems are boiler, turbine, generator, and condenser as shown in figure 2. the failure in any subsystem leads to stop of the unit and make it out of work. fig. 2. parts of unit 5. 3. methodology the proposed methodology to estimate the availability of “generator” in unit 5 of aldoura power station is divided in three stages as summarized in figure 3.the first stage included the description of the system under study and its sub-systems, as well as the collection of raw data, classification and organization of data to suit the required study. the second stage contained the application of the traditional methodology in determining the availability of the system and subsystems. the third and final stage is the application of artificial intelligence networks. asmaa j. awad al-khwarizmi engineering journal, vol. 18, no. 2, p.p. 112(2022) 4 fig. 3. the stages and steps of proposed methodology. the data collected from the generator of unit 5 for the years 2015 to 2018 are classified and arranged as shown in table 1, year 2015 was considered to be the zero hour, or the beginning of operation, and this is not the reality, due to the lack of real data for the operation of the system, the stop time or the maintenance and replacement time (ttr) is added in each case, which is the starting time for the unit to operate after performing maintenance on it in a cumulative aggregate, the types of failure is also shown in the last column of the table. asmaa j. awad al-khwarizmi engineering journal, vol. 18, no. 2, p.p. 112(2022) 5 table 1, data collected of the generator and type of failure. operation time stopping time from [hr.] to [hr.] ttr [hr.] type of failure 1 01/01/2015 00:00 16/07/2015 16:30 0.00 4720.50 1.5 electrical 2 16/07/2015 18:00 19/07/2015 13:45 4722.00 4789.75 0.75 electrical 3 19/07/2015 14:30 27/08/2015 11:45 4790.50 5723.75 1.5 electrical 4 27/08/2015 13:15 06/09/2015 15:30 5725.25 5967.50 2.5 electrical 5 06/09/2015 18:00 27/12/2015 12:00 5970.00 8652.00 2.25 electrical 6 27/12/2015 14:15 06/06/2016 10:30 8654.25 12538.50 1 electrical 7 06/06/2016 11:30 16/08/2016 08:45 12539.50 14240.75 0.75 electrical 8 16/08/2016 09:30 09/09/2016 08:30 14241.50 14816.50 1 mechanical 9 09/09/2016 09:30 30/09/2016 22:00 14817.50 15334.00 28.5 mechanical 10 02/10/2016 02:30 05/10/2016 16:30 15362.50 15448.50 0.75 mechanical 11 05/10/2016 17:15 29/10/2016 23:30 15449.25 16031.50 8.5 mechanical 12 30/10/2016 08:00 23/11/2016 15:15 16040.00 16623.25 1 mechanical 13 23/11/2016 16:15 27/11/2016 10:00 16624.25 16714.00 2.75 mechanical 14 27/11/2016 12:45 12/12/2016 14:00 16716.75 17078.00 29.75 mechanical 15 13/12/2016 19:45 10/05/2017 17:00 17107.75 20657.00 11.25 electrical 16 11/05/2017 04:15 11/05/2017 16:45 20668.25 20680.75 0.75 mechanical 17 11/05/2017 17:30 14/06/2017 17:30 20681.50 21497.50 2 mechanical 18 14/06/2017 19:30 14/06/2017 20:15 21499.50 21500.25 1 mechanical 19 14/06/2017 21:15 10/08/2017 14:30 21501.25 22862.50 1 mechanical 20 10/08/2017 15:30 10/08/2017 16:30 22863.50 22864.50 1.75 mechanical 21 10/08/2017 18:15 13/08/2017 00:45 22866.25 22920.75 60.5 mechanical 22 15/08/2017 13:15 22/10/2017 17:45 22981.25 24617.75 2 mechanical 23 22/10/2017 19:45 18/11/2017 13:00 24619.75 25261.00 0.5 control 24 18/11/2017 13:30 14/02/2018 22:00 25261.50 27382.00 1 mechanical 25 14/02/2018 23:00 12/05/2018 21:30 27383.00 29469.50 104.5 electrical 26 17/05/2018 06:00 12/06/2018 11:45 29574.00 30203.75 7.75 electrical 27 12/06/2018 19:30 03/08/2018 18:00 30211.50 31458.00 1.25 mechanical 28 03/08/2018 19:15 11/08/2018 04:45 31459.25 31636.75 17.25 mechanical 29 11/08/2018 22:00 23/09/2018 13:30 31654.00 32677.50 1.75 electrical 30 23/09/2018 15:15 30/09/2018 05:00 32679.25 32837.00 71.25 mechanical 31 03/10/2018 04:15 13/10/2018 05:30 32908.25 33149.50 4 mechanical 32 13/10/2018 09:30 16/10/2018 04:45 33153.50 33220.75 24 mechanical 33 17/10/2018 04:45 24/10/2018 23:00 33244.75 33431.00 17.75 mechanical 34 25/10/2018 16:45 01/01/2019 00:00 33448.75 35064.00 0 no failure all these data are entered to minitab17 software to select the appropriate functional distribution matching the data. the software can able to analysis (11) probability distributions, best four probability distribution graphs shown in figure 4, weibull, loglogestic, log normal, and exponential. weibull distribution is approved depends on the lowest value of anderson darling and highest value of correlation coefficient as shown in figure 5. asmaa j. awad al-khwarizmi engineering journal, vol. 18, no. 2, p.p. 112(2022) 6 fig. 4. graph of best distribution. fig. 5. anderson-darling and correlation coefficient values. 3.1 traditional method (weibull distribution) it is one of the most distributions that are used to evaluate the reliability of the system, it is a flexible distribution and gives a clearer and more realistic view of the life of the system, and it uses two number parameters in determining the behavior of the system [11]. this type of probability distributions is governed by two parameters; the first is the shape parameter (β), asmaa j. awad al-khwarizmi engineering journal, vol. 18, no. 2, p.p. 112(2022) 7 where it affects the approach or the distribution away from the main axis and the equation governing it. the second parameter is scale parameter (θ), who influenced the probability value when guessing the times. the reliability r (t) and availability a(t) functions for weibull distribution are given as: ���� = � �� � � �^ t>0 …(1) ���� = − ����/��^� t>0, β>0 …(2) the availability for the years (2015-2017) was calculated for the generator using equations 1 and 2 in minitab17 software as shown in table 2. table 2, availability of generator for the years (2015-2017) by minitab17 software. years from [hr.] to [hr.] ttr [hr.] a(t) weibull 1 2015 0.00 4720.50 1.5 0.95731 2 2015 4722.00 4789.75 0.75 0.955881 3 2015 4790.50 5723.75 1.5 0.934159 4 2015 5725.25 5967.50 2.5 0.927744 5 2015 5970.00 8652.00 2.25 0.837799 6 2016 8654.25 12538.50 1 0.658902 7 2016 12539.50 14240.75 0.75 0.57127 8 2016 14241.50 14816.50 1 0.541396 9 2016 14817.50 15334.00 28.5 0.514646 10 2016 15362.50 15448.50 0.75 0.508751 11 2016 15449.25 16031.50 8.5 0.478928 12 2016 16040.00 16623.25 1 0.449088 13 2016 16624.25 16714.00 2.75 0.444558 14 2017 16716.75 17078.00 29.75 0.426534 15 2017 17107.75 20657.00 11.25 0.266425 16 2017 20668.25 20680.75 0.75 0.26549 17 2017 20681.50 21497.50 2 0.234482 18 2017 21499.50 21500.25 1 0.234381 19 2017 21501.25 22862.50 1 0.187844 20 2017 22863.50 22864.50 1.75 0.18778 21 2017 22866.25 22920.75 60.5 0.186 22 2017 22981.25 24617.75 2 0.137531 23 2017 24619.75 25261.00 0.5 0.121751 24 2017 25261.50 26304.00 0 no failure until end 2017 weibull ���� = 2.31123, ����= 18302.9 3.2 non traditional method (artificial neural network (ann)) artificial neural network (ann) is one of the most important artificial intelligence techniques; the working concept is based on the artificial neurons which are the processing components. it can deal with noisy data or incomplete information, and it can be very efficient, especially in situations where it is impossible to describe the steps or rules that lead to the solution of the problem, and it can model the system using only samples, so it can be used to predict availability with a reliable and fast process. the network input layer has 2 neurons which related to time of generator working and the output layer houses the response factor in 1 neuron. the inputoutput gathering of data was divided into two groups: the training data group consist of the availability data obtained from the weibull traditional method for the years (2015-2017) and the test data containing the availability data obtained from the weibull traditional method for the year 2018. there are 24 training models considered for ann availability modeling. a trial and error method was selected to calculate the number of neurons in the hidden layer,. the best approach with a minimal mean squared error is done with eleven hidden layer neurons for availability having a regression model 0.99874, and the mean square error (mse) asmaa j. awad al-khwarizmi engineering journal, vol. 18, no. 2, p.p. 112(2022) 8 calculated using equation 3 was 5.6937e-06. fig.6 shows the architecture of the neural network that offers the highest predictive accuracy for the purpose of using it to estimate the availability in the future. mse = � ∑ ��� − ���^�� � …(3) fig. 6. neural network structure. 4. results and discussions the weights are fixed once the network has been trained, and the model is checked for accuracy. the model was validated using the verification data chosen as the availability of 2018 as shown in figure 7 to examine the predicted precision of the emerging neural network model. it is clear that there is a difference between the values of availability by weibull and ann, that is due to the fact that a real time failures of year 2018 did not used into accounting the parameters of (β) and (θ) in weibull distribution. this means that the application of neural networks gave better results and is closer to the studied reality of the collected data, because it takes into account any data that enters the network, and based on it, it changes the weights between the network layers to improve the estimation values. fig. 7. a(t) of testing year 2018 by ann & weibull . tables 3 shows the estimation results for the availability of the generator for year 2019 in every 100 working hours obtained by the ann structure. it is preferable to adopt more hours of operation in the estimated availability, because the (100 hours) operation has given close results. 0 0.05 0.1 0.15 0.2 0.25 0.3 1 2 3 4 5 6 7 8 9 10 11 12 a v a il a b il it y a (t ) months of year 2018 ann weibull asmaa j. awad al-khwarizmi engineering journal, vol. 18, no. 2, p.p. 112(2022) 9 table 3, estimate availability by (ann) for year (2019)/generator operation time from [hr.] stopping time to [hr.] estimating availability by ann a(t) 1 35000 35064 0.111788 2 35064 35164 0.111783 3 35164 35264 0.111776 4 35264 35364 0.111769 5 35364 35464 0.111763 6 35464 35564 0.111756 7 35564 35664 0.11175 8 35664 35764 0.111745 9 35764 35864 0.111739 10 35864 35964 0.111734 11 35964 36064 0.111729 12 36064 36164 0.111724 13 36164 36264 0.111719 14 36264 36364 0.111715 15 36364 36464 0.11171 16 36464 36564 0.111706 17 36564 36664 0.111702 18 36664 36764 0.111698 19 36764 36864 0.111695 20 36864 36964 0.111691 21 36964 37064 0.111688 22 37064 37164 0.111685 23 37164 37264 0.111681 24 37264 37364 0.111679 25 37364 37464 0.111676 26 37464 37564 0.111673 27 37564 37664 0.11167 28 37664 37764 0.111668 29 37764 37864 0.111665 30 37864 37964 0.111663 31 37964 38064 0.111661 32 38064 38164 0.111659 33 38164 38264 0.111657 34 38264 38364 0.111655 35 38364 38464 0.111653 36 38464 38564 0.111651 37 38564 38664 0.111649 38 38664 38764 0.111647 39 38764 38864 0.111646 40 38864 38964 0.111644 41 38964 39064 0.111643 42 39064 39164 0.111641 43 39164 39264 0.11164 44 39264 39364 0.111639 45 39364 39464 0.111637 46 39464 39564 0.111636 47 39564 39664 0.111635 48 39664 39764 0.111634 49 39764 39864 0.111633 50 39864 39964 0.111632 51 39964 40064 0.111631 52 40064 40164 0.11163 53 40164 40264 0.111629 54 40264 40364 0.111628 55 40364 40464 0.111627 56 40464 40564 0.111627 57 40564 40664 0.111626 asmaa j. awad al-khwarizmi engineering journal, vol. 18, no. 2, p.p. 112(2022) 10 58 40664 40764 0.111625 59 40764 40864 0.111624 60 40864 40964 0.111624 61 40964 41064 0.111623 62 41064 41164 0.111622 63 41164 41264 0.111622 64 41264 41364 0.111621 65 41364 41464 0.111621 66 41464 41564 0.11162 67 41564 41664 0.11162 68 41664 41764 0.111619 69 41764 41864 0.111619 70 41864 41964 0.111618 71 41964 42064 0.111618 72 42064 42164 0.111617 73 42164 42264 0.111617 74 42264 42364 0.111617 75 42364 42464 0.111616 76 42464 42564 0.111616 77 42564 42664 0.111615 78 42664 42764 0.111615 79 42764 42864 0.111615 80 42864 42964 0.111615 81 42964 43064 0.111614 82 43064 43164 0.111614 83 43164 43264 0.111614 84 43264 43364 0.111613 85 43364 43464 0.111613 86 43464 43564 0.111613 87 43564 43664 0.111613 88 43664 43764 0.111613 89 43764 43824 0.111612 5. conclusions in this study an ann model was developed to predict the availability aspects of generator in unit 5 of al-dourra electric power plant. the developed ann model is used to analyze the effect of process parameters at the time of failure and operating time of the system during three years (2015-2017), and the year 2018 was used as a test year to check the modeling work, and validate experimental results before developing a model. the primary conclusions of the investigation are given below: it is possible to take advantage of the methods of artificial intelligence represented by the artificial neural network for the purpose of building an intelligent model that can be used to guess the availability of an industrial system based on the scheduling of data of previous years. the (ann) gives a better estimate of the same cumulative operating time. the fact that the data used are few, and that this data was taken during the past four years only (2015-2018), not since the system began operating more than 30 years ago requires more effort to train the network and reach the best network structure to give results closer to reality. it is possible through which to build a preventive maintenance schedule and specify the date for the availability of the necessary spare parts, as well as the management of workers. -the larger the data, the greater the accuracy envisaged, so it is preferable to always update the data by adding data over the years, to update the layer weights. 6. references [1] g. s. sampaio, a. r. de aguiar, l. s. da silva, and l. a. da silva, " prediction of motor failure time using an artificial neural network," sensors, vol. 19, no. 4342, pp. 1-17, 2019. https://doi.org/10.3390/s19194342 [2] e. walter and l. pronzato, identification of parametric models from experimental data. asmaa j. awad al-khwarizmi 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[6] h. p. jagtap , a. k. bewoor , r. kumar, m. h. ahmadi, m. e. assad, and m. sharifpur, "ram analysis and availability optimization of thermal power plant water circulation system using pso,” energy reports, vol. 7, pp. 1133-1153, 2021. https://doi.org/10.1016/j.egyr.2020.12.025 [7] l. wang, h. hu, y. wang, w. wu, and p. he, " the availability model and parameters estimation method for the delay time model with imperfect maintenance at inspection, " applied mathematical modelling, vol. 35, pp. 2855-2863, 2011. doi:10.1016/j.apm.2010.11.070 [8] p. s. rajpal, k. s. shishodia, and g. s. sekhon, "an artificial neural network for modeling reliability, availability and maintainability of a repairable system, " reliability engineering & system safety, vol. 91, no. 7, pp. 809-819, 2006. doi:10.1016/j.ress.2005.08.004 [9] m. k. bhuyan, d. p. mohapatra, and s. sethi, "software reliability assessment using neural networks of computational intelligence based on software failure data, " baltic journal of modern computing, vol. 4, no. 4, pp. 1016-1037, 2016. http://dx.doi.org/10.22364/bjmc.2016.4.4.26 [10] m. kutyłowska, "neural network approach for availability indicator prediction, "periodica polytechnica civil engineering, vol. 61, no. 4 , pp. 873-881 ,2017. https://doi.org/10.3311/ppci.10429 [11] [s. mehmet, "availability analysis of a power plant by computer simulation, " international journal of energy and power engineering., vol. 9, no.4, pp. 495-498, 2015. )2022( 1-12، صفحة 2العدد، 18مجلة الخوارزمي الهندسية المجلد أسماء جمال عواد 12 تقدير وتحليل مدى أتاحية المولد في محطة توليد الطاقة الكهربائية باستخدام ann ***اللطيف أسامة فاضل عبد **أحمد عبد الرسول أحمد *أسماء جمال عواد قسم هندسة التصنيع المؤتمت/ كلية الهندسة الخوارزمي/ جامعة بغداد*،*** ** قسم الهندسة الميكانيكية/ كلية الهندسة/ جامعة بغداد _jamal_1992@yahoo.comasmaa البريد االلكتروني:* aa.alkhafaji@yahoo.com :البريد االلكتروني** drosamah@kecbu.uobaghdad.edu.iq :البريد االلكتروني*** الخالصة لصيانة مما كثرة األعطال في محطة الطاقة الكهربائية تؤدي إلى التوقف المفاجئ عن العمل. في بعض الحاالت، ال تتوفر المواد االحتياطية الالزمة ل رة لتوليد وسة بمحطة الديؤدي إلى انقطاع توليد الطاقة في وحدة محطة الطاقة الكهربائية. تناولت الدراسة الحالية تحديد أوجه توافر المولدات في الوحدة الخام ستوى التفاصيل التي تعتبر مناسبة لهذا المولد، تم إجراء مجموعة واسعة من الدراسات لجمع معلومات دقيقة على م تاحيةالكهرباء. من أجل تقييم أداء األ من خالل (ann) ، والشبكات العصبية االصطناعيةminitab 17 عبر weibull . يتم إجراء تحليل الموثوقية باستخدام توزيعألتاحية لتلبية هدف تحليل ا weibull) لحساب التوافر بالطريقة التقليدية (توزيع ٢٠١٧٢٠١٥االقتراب من التغذية إلى األمام، واالنتشار الخلفي. تم استخدام بيانات التشغيل لألعوام المولد أتاحيةقد تتنبأ ب ann للتحقق من النموذج. تقترح الدراسة أن ٢٠١٨وتدريب الشبكات العصبية االصطناعية، بينما تم استخدام البيانات من عام weibull.توزيع وإخراج ann بين التوافر الذي تنبأ به 5.6937e-06 (mse) خطأ مربعومتوسط 0.99874 (r) بمعامل ارتباط microsoft word -f'f h3h3f hdei2335 this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 17, no. 4, december, (2021) p. p. 2335 evaluation of the main causes of diesel engine injector failure using fault tree analysis hanan b. matar* sawsan s. al-zubaidi** luma a. al-kindi*** *,**,*** department of production engineering and metallurgy engineering / university of technology/ iraq pme.19.29@grad.uotechnology.edu.iqemail: * 70004@uotechnology.edu.iqemail: ** .iquluma.a.alkindi@uotechnology.edemail: *** (received 29 august 2021; accepted 29 december 2021) 6.0012https://doi.org/10.22153/kej.2021. abstract the maintenance of the diesel engine parts in any electric power station contains many problems that lead to stopping. several reasons lead to such problems; these reasons should be analyzed and evaluated in order to eliminate their effects. this paper is based on evaluation of the main causes that lead to diesel engine injector failure as a main part of electric power stations, using fault tree analysis (fta). the fta is the most broadly utilized strategies in the industrial area to perform reliability analysis of complex designing frameworks. a fault tree is a logical representation of the relationship of basic events that lead to a given unwanted event (i.e., top event). starting with introducing the fta and how it could be utilized in analyzing the reasons of main issues that lead to that the injector stops working, in which the probability of occurrence of each issue is calculated. the application of the root cause analysis principle of diesel engine injector failure in diesels haditha station is chosen as a case under study. according to the probabilities’ evaluation by using the fta based on of the causes under the top event its value was (0.80). it is concluded from the analysis that the three largest values of the occurrence of a problem with the diesel engine injector are 0.50 for fuel problems, 0.20 for overloads, and 0.18 for nozzle head corrosion. plant management can define a specific plan with taking into consideration the calculated value of each cause in order to reduce their impacts and to avoid long downtime hours compared to operating hours. finally, recommandations are suggested to overcome these causes. keywords: fault tree analysis (fta), fault tree symbols, injector, qualitative assessment. 1. introduction given the importance of maintenance of all kinds, it is recommended implementing it and adhering to the time and operating hours specified for its work. providing all maintenance requirements and tolerance for one minute under any circumstances, especially during peak work times, is essential in order to avoid a damage that may be caused to parts of the generating units and expose them to a stoppage. this state leads to energy loss, stopped production, and losses in lives and money. most engineering systems are maintained the mainteance work when they fail, and the maintenance work is performed on them to keep their operation. [1] fault tree analysis (fta) is one of the analytical methods for tracking events, which can be contributed to identify the most important parts that cause the malfunction or stoping the work. accordingly, the sub-causes of the problem is hanan b. matar al-khwarizmi engineering journal, vol. 17, no. 4, p.p. 2335 (2021) 24 displayed and the probability of an undesirable fault event is calculated. in this paper adopting the fta is considered in the proposed methodology to determine the main and sub causes, and their probabilities of the parts of power plants’ stoppage. the focus on the most influential causes probabilities in order is essential to find the solutions to these causes which significantly reduce the rate of breakdowns. 2. fault tree analysis (fta)  an fta begins with a top fault event and continues deductively by inquiring, "how could this event have occurred?". immediate contributing causes to this top fault event are distinguished and afterward recorded as a component of the following lower level of analysis (sub-faults). these sub-fault events are then associated as affecting contributions to the upper-level event by the same token either "and" gates or "or" gates. a definitive outcome is a qualitative fault tree ending in a bunch of basic faults and undeveloped events. [2] the fta is a technique for planning a fault tree that intelligently examines the causal relationship of a framework disappointment, and discovers the likelihood of a framework disappointment. [3] the fta is deductive in nature implying that the analysis begins with a top event (system failure) and works in reverse from the highest point of the tree towards the leaves of the tree to decide the root causes of the top event. [4] failure itself can be characterized as the interruption of an item's capacity, from a component to a complex system, to carry out its function. the failure of a part can be classified into three groups [5]: 1) primary failure, 2) a component is in a damaged state (non-working state), and 3) command faults. 3. the symbols used in the fta the essential symbols utilized in the fta are assembled as events, gates, and transfer symbols. fig.1 shows them with their definitions [6] [7] [8]: fig.1. the fault tree symbols. hanan b. matar al-khwarizmi engineering journal, vol. 17, no. 4, p.p. 2335 (2021) 25 4. research methodology the research methodology is based on applying the fta to evaluate and calculate the failure rate of the part under study. to arrange the work steps, a flowchart is used to define processes in sequence. the utilization of standardized symbols for represent the steps of methodology makes the flow chart simpler to decipher. [9] 4.1. proposed flow chart methodology the main steps in the proposed methodology are as follows: 1. describing of the whole system, and studying its work, to select the part with frequent failure with the ability to be maintained. 2. collecting all the data on faults and dividing them into main faults, in which the root causes of the main problems branch off, as to be illustrated in details in the qualitative assessment method followed. 3. after clarifying all the reasons that led to the failure of the part under study, the fta is drawn to analyze the problems more accurately and clearly. 4. applying steps (6) (to be illustrated in the following section), according to the type of gate (or or and) in order to get the top event and draw the fault tree with related values (quantitative assessment). 5. a bar chart is drawn to illustrate the most influential causes and to choose an appropriate maintenance plan that reduces breakdowns and costs. 6. suggesting solutions to reduce the influence of the occurrence are given. 7. if the suggestions improve the faults rates, then the aim is reached. but if not, new suggestions are given. fig.2. represents the steps of the proposed methodology processes. 4.2 the assessment of problem: a fault tree is evaluated as qualitative assessment or quantitative assessment. qualitative assessment is the kind of evaluation of an issue that has effectively occurred in a venture, to analyze the causes behind this issue. [10] in quantitative analysis, the probability of the top event and other quantitative dependability files, for example, significant measures are numerically determined, given the failure rate or probability of individual system component. [4] two equations are used according to the type of gate (and or or) for quantitative analysis[11]: for and gate out fault event eo is given by: … ( 1 ) and for or gate out fault event xo is given by : …( 2 ) concerning analysis procedures, recognizing qualitative the fta is performed, which thinks about the construction of the fta; and quantitative fta, which estimate the numbers, for example, disappointment probabilities for fault trees. [12] both qualitative and quantitative analyses bring a bunch of basic ways, often named "cut sets" or "min sets." these are group of parts that, when they happen, will cause a top fault event. [2] in the case study of this research, both qualitative and quantitative assessment are shown. hanan b. matar al-khwarizmi engineering journal, vol. 17, no. 4, p.p. 2335 (2021) 26 fig. 2. the flowchart of steps of the processes flow. hanan b. matar al-khwarizmi engineering journal, vol. 17, no. 4, p.p. 2335 (2021) 27 5. adopted case study the case study adopted in this paper is the diesel engine injector in haditha diesels station. the engine is a type of four-stroke internal combustion engine. under such circumstances, the focus will be on the injector as a highly effective part of the diesel engine. it is one of the parts of the fuel system whose function is to inject fuel in the form of a mist with a force (3000bar) that reaches the combustion chamber. the presence of the injector results in more efficiency and lower cost in terms of fuel exchange. the injector is shown in fig.3. fig. 3. the injector. 6. drawing the fault tree and calculations the fault tree is drawn from the data that the researcher collects (values and events) and were recorded through his attendance at the station and with the help of the engineer who is supervising the work and the workers. according to the data recorded in the power station foles, main and subcauses are named. table (1) lists the main problems and sub-causes events that cause the injector to stop working in order to draw a fault tree which represente the qualitative assessment as shown in fig.4. table1, the nomenclature of the main problems of the occurrence of malfunctions and their sub-causes. name of event symbol of event no maintenance order e1 high fuel temperature e2 work for long periods e3 fuel laden with water e4 water leakage from the heat sink e5 fuel laden with impurities e6 fuel filter has stopped working e7 accumulation of previous fuel impurities e8 neglect of maintenance manger e9 urgent need for e10 increased pressure e11 high temperature e12 other reasons e13 excessive pressure at the attached nozzle e14 over load e15 poor maintenance e16 water in fuel e17 viscosity of the fuel e18 impurities in the fuel e19 injector vibration e20 other reasons e21 water pressure e22 defect in the washer e23 fuel heat e24 overloads e25 delay maintenance time e26 nozzle head corrosion e27 nozzle head does not pump fuel e28 fracture of the injector hull e29 fuel problems e30 o-ring i e31 o-ring ii e32 diesel engine injector mal functioning e33 hanan b. matar al-khwarizmi engineering journal, vol. 17, no. 4, p.p. 2335 (2021) 28 fig.4. fault tree analysis of diesel engine injector. hanan b. matar al-khwarizmi engineering journal, vol. 17, no. 4, p.p. 2335 (2021) 29 the presence in the station and data collection were done based on the realized events (previous faults) and calculating the probabilities of the basic events is shown in table (2). table 2, the probability of occurrence of basic events. using the data provided by haditha diesel station company, according to their records as shown in table (2) and the fta the following calculators are performed, by apply 'or' or 'and' equation, as given: 1.the probability of event occurring e32 is (oring ii = 0.06), which means that the injector has stopped working due to a malfunction or breakage in the o-rings of the refrigeration system, as given (a very small percentage) 2.the probability of event occurring e31 is (oring i = 0.05), meaning that the injector stops are due to a malfunction or breakage in the fuel system's o-ring. (a very small percentage) 3. the probability of event occurring e19 is (impurities in the fuel = 0.20) caused by (e6 =fuel laden with impurities, e7 =fuel filter has stopped working, and e8 =accumulation of previous fuel impurities) as given: in addition, the probability of an event occurring e17 is (water in fuel = 0.10) caused by (e4 =fuel laden with water, and e5 =water leakage from the heat sink) as: with the probability of an event occurring e18 is (viscosity of the fuel = 0.30), giving the probability of an event occurring e30 as: (half the amount of failure) 4. the probability of an event occurring e15 is (over load = 0.50) caused by (e2 =high fuel temperature, e3 =work for long periods) as follows: events number e1 0 .1 e 2 0.55 e 3 0.89 e4 0.0 5 e5 0.05 e6 0.04 e7 0.10 e8 0.06 e10 0 .05 e11 0.30 e12 0.60 e 13 0 .05 e14 0. 05 e16 0.20 e18 0 .30 e20 0. 20 e21 0.50 e22 0.50 e23 0.01 e24 0.05 e25 0.20 hanan b. matar al-khwarizmi engineering journal, vol. 17, no. 4, p.p. 2335 (2021) 30 the probability of an event occurring e15 (over load) with probability of an event occurring e16 (poor maintenance) give the probability of an event occurring e29 as follows: (small percentage) 5. the probability of an event occurring e28 is (nozzle head does not pump fuel =0.10) as: (small percentage) 6. the probability of an event occurring e27 is (nozzle head wear =0.18) as: (medium rate of faults) 7. the probability of an event occurring e9 is (neglect of maintenance manager =0.10) caused by one event (e1 =no maintenance order) as: with the probability of an event, occurring e10 is (urgent need for operation =0.05), giving the probability of an event occurring e26 as follows: (medium rate of faults) 8. the probability of an event occurring e25 is (over loads =0.20) 9. calculation the probability of occurrence of the top event e33 is (diesel engine injector mal functioning =0.80) as follows: (top event) fig.5. shows the fta with the values of the probability indicating the given error event and their occurrence with the calculated probabilities. (quantitative assessment). hanan b. matar al-khwarizmi engineering journal, vol. 17, no. 4, p.p. 2335 (2021) 31 fig. 5. fault tree analysis with the values. hanan b. matar al-khwarizmi engineering journal, vol. 17, no. 4, p.p. 2335 (2021) 32 7. results and discussion after calculating the failure rate of each cause that lead to injector failure and plotting the fta with the values as shown in fig.5., a bar chart is drawn to show the differences between the rates of faults causes and the most influential failures, which is shown in fig.6. fig. 6. the faults that occur to the diesel engine injector. the bar chart is the best choice for comparing the calculated data to be represented in a way that shows the data which divided into nominal, numeric, and even symbolic categories. here, the vertical bar chart is chosen, so that the longer bar is the greater size of the category. in fig.6., the sum of rates gives a percentage of 98% and not 100%, this means that 2% is still not calculated and represents “other reasons” affecting the diesel engine injector malfunction, which is unknown factors. looking at the shape of the chart and based on the columns that represent the probability of faults occurrence, we find that the largest is fuel problems, followed by over loads, and then nozzle head corrosion. by analyzing the main reasons for the occurrence of these faults through the fta several solutions are suggested to reduce these faults. for discussing these results and according to the presentation and calculations, the followings points are highlighted: 1. in the fta, the focus of the researcher is to identify the main causes firstly and then to identify their sub-causes, with assuming that no error occurs in identifying the causes. 2. for logical consideration, the two gates or and and are used for linking in the plotted fault tree. 3. to solve the root causes, it is possible to significantly reduce the percentage of errors that causes the injector to stop working. 4. the bar chart is used to compare the results of the data, showing the largest failure rates according to the length of the vertical bar. 5. it is concluded from the bar chart that the three largest values of the occurrence of a problem with the diesel engine injector are e30= 0.50 (fuel problems), e25= 0.20 (overloads), and e27= 0.18 (nozzle head corrosion). 8. conclusions and recommendations through the calculations, it is found that the main and sub-causes lead to the clarity of the probability of failure by 80%, which was a high percentage of failure. by studying the ratios of the main causes as shown in the bar chart in fig.6., we have to focus on the most influential causes in order to find the solutions to these causes which significantly reduce the rate of breakdowns. several plans and ideas have been proposed to solve and reduce these rates: hanan b. matar al-khwarizmi engineering journal, vol. 17, no. 4, p.p. 2335 (2021) 33 1. new maintenance plan is determined in which not only the rate of failures but also cost is reduced. the new maintenance plan depends on two types of maintenance according to the type of malfunction, these are : a. preventive maintenance (periodic) is done by supervising an engineer with (4-6) workers. b. corrective maintenance (emergency) is done by workers with or without the supervising an engineer who performs quick and sudden. maintenance such as a leak or breakage in a part of the injector that is replaced or repaired immediately to restart the engine; this type of maintenance does not depend on a specific time . 2. the cause e30 = 0.50 (fuel problems) can be reduced by : a. replacing the fuel filter every certain period of time to reduce the amount of impurities . b. checking the fuel before filling it into the engine to ensure its purity. 3. the cause e25 = 0.20 (overload), the rate of failures due to overloading increases with high temperatures, high pressures and electrical energy consumption, especially in summer. this rate can be reduced by : a. supplying water cooling systems to cool the injector . b. organizing a schedule for operating the motors to avoid power outages due to excessive loads. 4. the cause e27 = 0.18 (nozzle head corrosion) can be reduced by adjusting (o-ring) the nozzle of the cooling system, to prevent water leakage causing rust in the injector head. notation p (eo) = occurrence probability of the and gate output fault event, eo n = total number of independent input fault events p (ei) = probability of occurrence of input fault event ei, for i=1, 2, 3,… ,n. p (xo) = occurrence probability of the or gate output fault event, xo k = total number of independent input fault events p (xi) = probability of occurrence of input fault event xi, for i =1, 2, 3,… ,k . 9. references [1] patrick, d.t. o’connor and ander kleyner, "practical reliability engineering", fifth edition, wiley, a john and sons, ltd., publication, this edition first published 2012 in john wiley & sons, ltd, pp. 263. 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[7] sohag kabir, an overview of fault tree analysis and its application in model based dependability analysis, school of engineering and computer science, university of hull, hull, hu6 7rx, uk, pp.3, ©2018, elsevier. this manuscript version is made available under the cc-by-nc-nd4.0license http://creativecommons.org/licenses/by-nc-nd/4.0/ [8] l. y. waghmode and rajkumar b. patil,"an overview of fault tree analysis (fta) method for reliability analysis", department of mechanical engineering, annasaheb dange college of engineering and technology, ashta, shivaji university, kolhapur, maharashtra (india), march 2013, pp. 3. hanan b. matar al-khwarizmi engineering journal, vol. 17, no. 4, p.p. 2335 (2021) 34 [9] christine m. walsh-kelly, flow chart/process flow diagram ,md,8-26-2015,p.p1,2, http://www.ihi.org/education/ihiopenschool/resou rces/pages/boblloydwhiteboard.aspx#fc [10] abbas m. burhan, "fault tree analysis as a modern technique for investigating causes of some construction project problems ", baghdad university, college of engineering, june 2010, pp. 4. 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[12] enno ruijters and marielle stoelinga, "fault tree analysis: a survey of the state-ofthe-art in modeling", analysis and tools, formal methods and tools, university of twente, the netherlands, 2014,pp.3. ) 2021( 2335، صفحة 4العدد، 17مجلة الخوارزمي الهندسية المجلد حنان بشار مطر 35    تقييم قابلية الصيانة لمكونات منتج للتخطيط االمثل للصيانة **سوسن صبيح عبد* حنان بشار مطر *** لمى عدنان حميد العراق هندسة االنتاج والمعادن /الجامعة التكنلوجيا/*,**,***قسم pme.19.29@grad.uotechnology.edu.iq*البريد االلكتروني: uotechnology.edu.iq@70004***البريد االلكتروني: luma.a.alkindi@uotechnology.edu.iq***البريد االلكتروني: الخالصة ؛ يجب تتضمن صيانة أجزاء محرك الديزل في أي محطة كهرباء العديد من المشاكل التي تؤدي إلى التوقف. عدة أسباب تؤدي إلى مثل هذه المشاكل لرئيسية التي تؤدي إلى فشل حاقن محرك الديزل كجزء رئيسي من األسباب ا لى تقييم تحليل هذه األسباب وتقييمها من أجل إزالة آثارها. تستند هذه الورقة إ ) األعطال تحليل شجرة أن األعطال. شجرة تحليل باستخدام ، الكهربائية الطاقة في ftaمحطات واسع نطاق على استخداًما االستراتيجيات أكثر هو ( التي تؤدي وليةالقة األحداث األساسية / األة. شجرة األعطال هي تمثيل منطقي لعالتصميم المعقدر أطمن خالل الصناعية إلجراء تحليل موثوقية مجاالت ال ). رئيسيإلى حدث معين غير مرغوب فيه (على سبيل المثال ، الحدث ال ى توقف الحاقن عن العمل من إلي ) وكيف يمكن استخدامه في تحليل أسباب المشكالت الرئيسية التي تؤد fta(تحليل شجرة االعطال البدء بتقديم تم لفشل حاقن محرك الديزل في محطة الديزل خالل حساب احتمال حدوث كل مشكلة. دراسية حديثة كحالة في تم اختيار تطبيق مبدأ تحليل السبب الجذري من التحليل بان اكبر تم االستنتاج ).٠٫٨٠( متهقيت ، كان الرئيسيحدث للالمؤدية سباب تحليل شجرة االعطال لال. وفقًا لتقييم االحتماالت باستخدام تطبيقية يمكن إلدارة المصنع تحديد لتأكل راس النوزل ٠٫١٨الي و الع للحمل ٠٫٢لمشاكل الوقود، ٠٫٥ت القيم المحتملة السباب العطل لحاقن محرك الديزل كان آثارها لتقليل سبب لكل المحسوبة القيمة االعتبار في األخذ مع محددة التوقأ منخطة ساعات تجنب التشغيلجل بساعات مقارنة الطويلة اقتراح .ف تم توصيات للتغلب على هذه المسببات. this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 20, no. 2, june, (2024), p p. 6572 gsm-enabled wireless patient monitoring system integrating microcontroller for managing vital signs tariq emad ali*, faten imad ali**, máté tejfel*** and alwahab dhulfiqar zoltán**** *,**university sains malaysia, gelugor 11800, penang, malaysia ***,**** faculty of informatics, eötvös loránd university, budapest, hungary corresponding author: *email: tariqemad@kecbu.uobaghdad.edu.iq **email: fatenemadali@gmail.com ***email: matej@inf.elte.hu ****email: dolfi@inf.elte.hu (received 20 november 2023; accepted 23 may 2024; published 1 june 2024) https://doi.org/10.22153/kej.2024.05.001 abstract the primary focus of this project is developing a cutting-edge remote monitoring of patients device for use in an intensive care unit (icu). the gadget is designed to capture and transmit vital health data from the patient's body, including oxygen saturation levels, heart rate, and temperatures. it is also capable of monitoring a pacemaker. information is then sent to a remote location after that. the suggested system receives the patient's vital signs and uses them as input on a computer in the nursing room. this transmission is made possible via a transmitter-receiver system consisting of two arduino kits connected to bluetooth devices. if any anomalous numbers are discovered as the data is processed, the computer notifies the doctor via the global system for mobile communications (gsm) and the doctor's mobile device. the primary objective of this device is to enable remote monitoring of a patient's medical parameters and prompt alerting of doctors who are situated in remote places of any concerning circumstances. the doctor's mobile device receives the collected values from the workstation. the entire system's structure is implemented using the visual basic programming dialect. keywords: arduino kit; medical sensors; bluetooth; visual basic; gsm mobile; icu 1. introduction the subject of health monitoring has significantly advanced as a result of breakthroughs in the biological sciences and healthcare field [1]. many applications have been studied in-depth over the years, including emergencies, home care, hospitals, military, and sports training [2]. in the field of health monitoring, the use of telemedicine has been crucial [3]. the intensive care unit (icu) network serves as an example of how this technology facilitates remote monitoring and diagnosis by enabling the electronic communication of a patient's medical information [4]. icu networking entails using communication protocols to connect icu pcs (clients) to a nursing room pc (server) across local area networks (lans), metropolitan area networks (mans), or other networks. these protocols are essential for smooth communication between computers that have different operating characteristics. this enables nursing personnel who are not physically present in the icu to recognize problematic circumstances right once. the doctor's mobile device can then get these alerts immediately abdirahman et.al. 2023 [5]. the arduino platform, an open hardware board that has transformed robotics and control projects, was made possible by the advancement of microcontrollers. the open hardware programming mailto:fatenemadali@gmail.com mailto:dolfi@inf.elte.hu https://doi.org/10.22153/kej.2024.05.001 noor a. mohammed al-khwarizmi engineering journal, vol. 20, no.2, p.p. 6572 (2024) 66 language (arduino c) developed by arduino is well-known for being easy to use, and it can be integrated with engineering languages such as matlab and java. it is a well-liked option among microcontroller kinds because of its ease of use and programming capabilities brocker et. al., 2023 [6]. although there has been a great deal of research in this area, more work has to be done to demonstrate the medical benefits and economic feasibility of these solutions. experts like g. virone et al. 2023 have created concepts for innovative healthcare based on mobile sensor networks (wsns), highlighting the potential for low-cost deployment of integrative sensors to enhance quality of care [7]. bk harsha et al., 2023 [8] state that this technique provides women with protection during moments of insecurity, enabling people to venture forth with trust. in a threatening circumstance, a woman may use the tool's warning button to defend itself by utilizing analgesic inject in addition to the poison. the device incorporates an automatic painkiller injector, an alarm, a stun gun, an arduino uno, and technologies like gps and gsm. a handheld actual time global surveillance device that enables controlled manipulation of a patient's heart rate and oxygen level in the blood was developed in 2023 by dr. deepak et al. with an operational area of 10–15 square meters, the gadget was built utilizing zigbee connectivity and may monitor medical in customer houses [2]. a patient monitoring device was used in this research to keep an eye on the patient's condition in real time. the main element of the design of the system was an arduino framework computer kit, which was utilized to send critical medical data from the patient's body over a bluetooth network. the intensive care unit (icu), a computer with special capabilities dedicated with gathering and evaluating this critical information, received the data from a remote location. by avoiding problems with connection and data transmission dependability, this method offers a substitute to the traditional usage of networks of computers for the observation and exchange of significant data. 2. proposed work the purpose of this study is to develop a wireless clinical monitoring device and can measure and track the vital indicators of a person, including body temperature, heart rate as indicated by blood pressure measurements, and the ability of cardiac pacemakers to regulate erratic heartbeats. this method is shown in figure 1. fig. 1. general block diagram of the monitoring system. 2.1 system descriptions the purpose of this research is to create a wireless medical monitoring system capable of tracking a person's health, involving their internal temperatures and heart rate, as determined by pressure measures, as well as pacemaker-assisted heart control. figure 1 illustrates this strategy. fig. 2. main components of the health monitoring system. noor a. mohammed al-khwarizmi engineering journal, vol. 20, no.2, p.p. 6572 (2024) 67 2.1.1 sensors the ports on the arduino were used to attach a variety of medical sensors to gather and track the patient's vital signs. a) the temperature sensor is in charge of taking the patient's body temperature and determining how they are feeling right now. b) the number of heartbeats per minute, or heart rate, is depicted in figure 3, each heartbeat represents a representation of the heart's contraction and relaxation. c) the pacemaker sensor is a tool for controlling irregular cardiac rhythms. the input/output leads, sensor circuit, and pulse generator are its three basic components. the electrodes known as the input/output leads are affixed to the heart chambers and serve to transfer signals from the heart to the pulse generator and the pacemaker's output back to the heart. the heart's input signal is processed by the sensor circuit, and the output—a square wave—is utilized by the pulse generator. fig. 3. circuit diagram of heart rate [9]. the pulse generator, which functions as a preprogrammed microprocessor, is an essential part of the pacemaker. through the sensing circuit, it receives input signals from the heart and responds by sending stimuli back to the heart. as shown in figure 4, these stimuli are produced in line with the generator's pre-programmed schedule. it's important to remember that the pacemaker's pacing mode should only be used when required to avoid interfering with the heart's normal pacing process [10]. this guarantees that the pacemaker will only need to intervene when the heartbeat doesn't follow its typical pattern. when it comes to artificial pacing, the r wave represents the ventricular contraction that pumps blood into the main arteries. a single-chamber pacemaker works in the following order: reset timer, wait, and pace. it is designed to regulate only one chamber of the heart. the pacemaker detects an r wave, counts down to 0.83 seconds—typically the gap between two r waves—and then goes into the reset timer state. during this waiting period, the gadget returns to the wait mode if another r wave is detected. if no more r waves are found during the wait, the pacemaker switches to the pace mode and uses leads to stimulate the heart with electricity. by syncing with the heart's natural rhythm and only stimulating the pacemaker when a normal pulse is absent, this clever pacing mechanism makes sure that the pacemaker only acts when needed [8]. fig. 4. block diagram of pacemaker. noor a. mohammed al-khwarizmi engineering journal, vol. 20, no.2, p.p. 6572 (2024) 68 oximeter sensor: as seen in figure 5, the oximeter sensor is a complex circuit made up of red and infrared leds that produce the corresponding wavelengths. these wavelengths are sent to a photodiode detector via the finger. a portion of these wavelengths are absorbed by blood vessels, especially arterioles, in the finger. the percentage of oxygen saturation, or the proportion of oxyhemoglobin and deoxyhemoglobin molecules to total hemoglobin molecules, determines the absorption ratio. one photodiode receives the wavelengths that are delivered by both leds. the received light then passes through some procedures. by producing pulses at the proper repetition rate, a timing circuit functions as a digital switch. then, using an operational amplifier (opamp) in a current-to-voltage converter circuit, these pulsed wavelengths—both red and infrared—are amplified and converted to voltage. a sample and hold circuit is used to separate the wavelengths separately because the pulsatile nature of arterial blood flow causes the wavelengths to be received in pulsed form. control pulses for the sample and hold circuit are produced once again using the timing circuit. after that, a band-pass filter is used to filter out both highand low-frequency noise from the output voltage. ultimately, the voltage signal is cleaned and delivered to an arduino, which uses bluetooth to transform it into a digital signal that can be sent to a computer [11]. fig. 5. block diagram of oximetry sensor [11]. 2.1.2 connecting the bluetooth with microcontroller kit (arduino) using a particular communication protocol, bluetooth is a wireless communication technology that allows data to be sent between devices across short distances. bluetooth is employed in this work to enable the transfer of data from medical sensors to a computer. as shown in figure 6, this is achieved by connecting the bluetooth module— more precisely, the hc-05 bluetooth module—to an arduino uno microcontroller kit on both ends. the arduino kit and the bluetooth module communicate wirelessly over the serial. to do this, mark two pins on the arduino board to act as the serial port connection points between the arduino and the bluetooth shield. the arduino's tx pin is linked to the bluetooth module's tx (transmit) pin, and the arduino's rx (receive) pin is linked to the bluetooth module's tx pin. it is possible to enable data transfer using suitable arduino software. as seen in figure 7, the system's overall function is designed to monitor the patient's condition by effortlessly sending critical data from the sensors to the computer via this bluetooth-enabled configuration. noor a. mohammed al-khwarizmi engineering journal, vol. 20, no.2, p.p. 6572 (2024) 69 fig. 6. shows the block diagram of bluetooth connection with microcontroller kit (arduino). fig. 7. the interface between personal computer and mobile phone through gsm modem. 2.1.3 connecting mobile phone with personal computer advancements in mobile phone technology in recent times have made it possible to send short message service (sms) messages from a computer to a mobile phone using various programs. within the framework of the monitoring system that is being described, this technology is activated either upon detection of a medical condition that is dangerous or high-risk or upon the achievement of a predetermined threshold. in these situations, the monitoring system instantly notifies the doctor of the emergency by sending sms notifications via the global system for mobile communication (gsm) to their cell phone. the sms gateway is responsible for handling sms transmission. the contact number of the attending physician is kept up to date in a database maintained by the patient information management system. consequently, the system sends an sms after starting a database query. using the patient's id guarantees that the sms message with precise information about the patient's health reaches the appropriate doctor. the responsible healthcare professional and medical monitoring system may communicate promptly thanks to this integrated system. 3. working of the system the clarity of the health monitoring system's operational procedures and decision-making processes is enhanced through the visual representation provided in figure 8, which depicts the system's flowchart. this graphical representation offers an accessible means of understanding how the system functions and the sequential steps it undertakes to monitor and respond to a patient's health state. the comprehensive flowchart serves as a valuable tool, summarizing the intricate reasoning and procedures utilized across the entirety of the health monitoring system, contributing to a more insightful comprehension of its functionality. noor a. mohammed al-khwarizmi engineering journal, vol. 20, no.2, p.p. 6572 (2024) 70 fig. 8. flowchart illustrates the overall system mechanism. 4. implementing the proposed system our surveillance method's installation is the result of careful preparation, creative engineering, and a resolute dedication to the highest standards of medical technology. every element of our execution, from the deliberate design of the software's structure to the meticulous selection of equipment, has been created with intention and accuracy. we go into great detail in the parts that proceed, emphasizing the user-centric designs, strong security measures, future-ready capacity, and the smooth integration of hardware and software as the main components that make the system, we are using rich yet efficient. 1. equipment collaboration: we start the process by carefully choosing and integrating components that are made to specifically address health care tracking requirements. this consists of networking devices for smooth data transfer and detectors that record vital indicators including blood sugar, humidity, and pulse. every component of the hardware is put through a thorough certification and validation process to guarantee peak functionality and dependability in actual medical settings. 2. visual basic programming expertise: we create a program architecture which will function as the nerve center for the control structure by utilizing the powerful features of visual basic version 6. each element of the program, from the layout of the interface to computing algorithms, is painstakingly designed to satisfy the highest requirements for accuracy and reliability. noor a. mohammed al-khwarizmi engineering journal, vol. 20, no.2, p.p. 6572 (2024) 71 3. integration architecture: a complex integrative design is responsible for coordinating the smooth operation of hardware and software components under each other. this covers the protocols used for sending data safely across several networks, as well as middleware layers for data translation and protocol transformation. as a consequence, a coherent system is created in which many components cooperate to give doctors useful information. 4. user-centric design: the needs and tastes of users as well as healthcare providers are carefully considered throughout the creation of the interface for patients seen in figure 11. the user engagement is streamlined by the interface's obvious visual signals and functionalities, which are arranged naturally. users may customize their monitoring experience and be updated regarding their physical condition with features like real-time notifications and customizable displays. 5. compliance and security measures: tight legal and safety procedures are followed during the setting up phase to guarantee the protection of private medical information. this entails access control methods for user authentication, encryption techniques for data transfer, and routine security checks to find and fix any weaknesses. 6. scalability and future-proofing: as medical technology advances, our solution can easily expand and include novel functions since it is built with these two factors in mind. usability with current healthcare systems is ensured by flexible designs and open standards, while longterm viability and performance optimization are guaranteed by continuous upkeep and assistance initiatives. our solution exceeds the constraints of conventional surveillance equipment and ushers in a new era of proactive healthcare management by fusing various disparate pieces into a coherent whole. our surveillance system, with its advanced software architecture, user-centric design theory, and strong hardware facilities is ready to transform the way medical data is collected, analyzed, and used to enhance treatment of patients. lastly, we graphically represent the result of our work in figures 9 and 10, which illustrate how all of the hardware and software components work together to produce a cohesive whole. the illustrations show how the software platform and the physical framework operate together seamlessly, giving a clear picture of the complex unification process. the creative combining technique at the heart of our monitoring system allows vital medical data to be seamlessly collected, processed, and transmitted. as seen in figure 11, this strategy not only guarantees a successful flow of information but also establishes the framework for an interface that is easy to use. this interface acts as the starting point for interactions between medical personnel and patients, promoting effective dialogue and ensuring thorough surveillance of health. fig. 9. hardware implementation of monitoring systems fig. 10. hardware implementation of monitoring systems with gsm and mobile phone. noor a. mohammed al-khwarizmi engineering journal, vol. 20, no.2, p.p. 6572 (2024) 72 fig. 11. monitoring systems gui. 5. conclusions by using a bluetooth connection between the first and second arduino, the system gains more versatility. with this configuration, the server's pc may receive real-time vital signs and parameter data transmissions. alarm messages can also be sent to a mobile phone to notify the person in charge of the patient's status. utilizing the hc-05 bluetooth module is essential as its range of about 10 meters is enough to cover a sizable structure and ensure smooth data transfer. the hc-05 module, interestingly, uses different pins for tx (transmit) and rx (receive) connections instead of using the pins on the microcontroller kit (arduino) port. because these distinct pins are devoted to the bluetooth module, this design decision helps to decrease reaction times for data transmission and reception. the effective transfer of data from all the sensors to the mobile phone is made possible by the use of the gsm network, which has a faster baud rate. this improves the system's responsiveness and data transmission capabilities even more. references [1] ali, f.i., ali, t.e. and al-dahan, z.t., 2023. private backend server software-based telehealthcare tracking and monitoring system. international journal of online & biomedical engineering, 19(1). [2] arora, k., kumar, v., prashar, d. and tripathi, s.l. eds., 2023. modern computational techniques for engineering applications. crc press. [3] ali, f.i., ali, t.e. and hamad, a.h., 2022, october. telemedicine framework in covid-19 pandemic. in 2022 international conference on engineering and emerging technologies (iceet) (pp. 1-8). ieee. [4] shah, a.m., 2023. telemedicine in india: a perspective, collaboration, and knowledge sharing. national journal of physiology, pharmacy and pharmacology, 13(8), pp.15971597. [5] abdirahman, a.a., hashi, a.o., dahir, u.m., elmi, m.a. and rodriguez, o.e.r., enhancing vehicle tracking through sms: a cost-effective approach integrating gps and gsm. [6] brocker, a., schäfer, r., remy, c., voelker, s. and borchers, j., 2023. flowboard: how seamless, live, flow-based programming impacts learning to code for embedded electronics. acm transactions on computer-human interaction, 30(1), pp.1-36. [7] singh, s. and shanker, r., 2023. development of a robust structural health monitoring system: a wireless sensor network approach. asian journal of civil engineering, 24(4), pp.1129-1137. [8] harsha, b.k., shruthi, m.l.j., gn, n.k., chaitra, k.u., lokesh, d. and mahendrakar, p.n., 2023, october. empowering women’s safety: a comprehensive gps and gsm-enabled automated anesthesia and pepper spray defense system. in 2023 7th international conference on i-smac (iot in social, mobile, analytics and cloud) (i-smac) (pp. 1077-1081). ieee. [9] http://duino4projects.com/diy-arduino-pulsesensor [10] bikki, p., dhiraj, y. and nivas kumar, r.v.s., 2023. design and implementation of a sense amplifier for low-power cardiac pacemaker. journal of circuits, systems and computers, 32(09), p.2350148. [11] aldana londoņo, k., 2023. pulse oximeter: study and design. http://hdl.handle.net/2445/200772 http://duino4projects.com/diy-arduino-pulse-sensor http://duino4projects.com/diy-arduino-pulse-sensor http://hdl.handle.net/2445/200772 microsoft word 5'/b (fj'f h9(/ 'dc'8e 1319 al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 17, no. 1, march, (2021) p. p. 1319 experimental study of the influence of nanoparticles additive to diesel fuel on the emission characteristics sadiq talal bunyan* abed al-khadhim m. hasan ** *,**department of mechanical engineering / university of technology / baghdad / iraq *email:sadiqtalal1993@gmail.com **email: akm1@yahoo.com (received 16 july 2020; accepted 9 december 2020) https://doi.org/10.22153/kej.2021.12.002 abstract the present experimental work is conducted to examine the influence of adding alumina (al2o3) nanoparticles and titanium oxide (tio2) nanoparticles each alone to diesel fuel on the characteristic of the emissions. the size of both alumina and titanium oxide nanoparticles which have been added to diesel fuel to obtain nano-fuel is about 20 nm and 25 nm respectively. three doses of (al2o3) and (tio2) were prepared (25, 50 and 100) ppm. the nanoparticles mixed with gas oil fuel by mechanical homogenous (manual electrical mixer) and ultrasonic processor. the study reveals that the adding of aluminum oxide (al2o3) and titanium oxide (tio2) to gas oil (al2o3+df) and (tio2+df) improves the emissions characteristic of engine such as co emissions are reduced by 34.28% and 20.5% for tio2+df and al2o3+df respectively at 25ppm, the emissions of co2 increased by about 1.75% and 2.27% for tio2+df and al2o3+df respectively at 100ppm, the emissions of nox decreased by about 37.7% and 12.2% for tio2+df and al2o3+df respectively at 25ppm and the emissions uhc decreased by about 16.9% and 13.5% for tio2+df and al2o3+df respectively at 25ppm. keywords: alumina, diesel, emission characteristic, nanofuel, titanium oxide. 1. introduction diesel fuel is one of the world's largest sources of pollutants, where the burning of diesel fuel in compression ignition engine producing unburned hydrocarbons (uhc), nitrogen oxides (nox) and carbon monoxide (co). additionally, produce small amounts of sulfur oxides (sox) [1]. however it also, produces carbon dioxide (co2) which is a friend of the environment, oxygen (o2) and water vapor (h2o). so the researchers using several additives to diesel fuel especially the nanoparticles in recent years to resolve the problem of emissions [2]. the nano-fuel can define as a mixture of both diesel fuel and dosage of nanoparticles, which has different properties than net diesel and called also modified diesel.[3] the studies have shown that the addition of nanoparticles enhances the performance of the engine such as reducing specific fuel consumption and increasing thermal efficiency [4].the enhancement of the surface to volume ratio due to adding nanoparticles leads to decreasing the concentration of pollutants and increasing the rate of reaction [5].the expect reason of making the reaction faster due to a short delay period comparing to pure diesel [6]. nanoparticles are worked to enhance some physical properties of a lot of fluids including diesel fuel [7].where, it has been noticed that the nano additive to diesel (nanoparticles+ diesel) improve the fire point, flash point, viscosity, density and the other properties depending on the doses of nanoparticles [8].the particles which are suspended in diesel fuel increase effective thermal conductivity, the surface area of contact [9].also, reducing the sadiq talal bunyan al-khwarizmi engineering journal, vol. 17, no. 1, p.p. 1319 (2021) 14 exhaust emission such as unburned hydrocarbons (uhc), nitrogen oxides (nox) and carbon monoxides (co) [10]. this present experimental research will study the influence of alumina (al2o3) and titanium oxide (tio2) nanoparticles on the emission characteristics. although utilizing nanoparticles in diesel fuel have several advantages, the utilizing nanoparticles may involve several disadvantages such as increase in pumping power, higher viscosity (undesirable level) and block the nozzles due to agglomerate the nanoparticles [11]. there are many types of nanoparticles [12]; these are shown in the table (1). table1, types of nanoparticles 2. experimental setup the engine used in the experimental tests is fiat diesel engine, four cylinders, 4-stroke, direct injection, natural aspirated, closed water-cooled cycle with a displacement volume (3.666 l) and fitted with a hydraulic dynamometer. figure (2.1) shows the test engine with its equipment. the specifications of engine test are given in table (2). the type of additive nanoparticles is alumina (al2o3) and titanium oxide (tio2). the selection of doses depends on primary experimental results and researchers' results [13]. the chosen doses are (25, 50, and 100) ppm. the size of both alumina and titanium oxide nanoparticles is 20 nm and 25 nm respectively. the nanoparticles blended with fuel each one by mechanical homogenous (manual electrical mixer) for one hour in order to prevent the gathering of particles rapidly and ultrasonic processor up200ht (power 200w and frequency 26 khz) to disperse the nanoparticles and distribute them equally in the base fuel. all the exhaust gases emissions from the engine studied (unburnt hydrocarbon (uhc), co2, co and nox) are measured by using the gas analyzer. the gas analyzer model airrex hg-550 used to measure the exhaust emission by two principles which are electro-chemical principle for measuring nox and o2 and non-dispersive infrared principle for measuring (uhc, co2, and co). the measurements for thermophysical properties of nano diesel and diesel are shown in table (3). where the viscosity, density and the flash point and fire point were measured for both diesel and nano-diesel at university of technology/ department of chemical engineering. cetane number was measured for both diesel and nano-diesel at university of babylon / department of polymer engineering. the calorific value of diesel and nano-diesel was measured at middle refineries company/ quality control laboratories department. fig. 1. the test engine. examples nanoparticle no ferric chloride (fecl3), iron and aluminum metal 1 alumina, cerium oxide, zinc oxide, mno, tio2 metal oxides 2 glycerin organic additives 3 ferro fluids magnetic nano fluid 4 alloyed nanoparticle, a170cu30 composite material 5 tic, sic carbon nanotube 6 al+al2o3, cu+c layered 7 sin, ain nitride ceramics 8 ceo2 earth oxide 9 sadiq talal bunyan al-khwarizmi engineering journal, vol. 17, no. 1, p.p. 1319 (2021) 15 fig. 2. gas analyzer. table 2, tested engine specification. table 3, thermophysical properties of nano diesel. 3. result and discussion this section introduces the results obtained from experiments, where the results include: 3.1 carbon monoxide (co) emission the influence of nanoparticles doses level and types on co emission for diesel fuel is shown in figure (2) and figure (3).the figures reveal that the co emission decreases with adding tio2 and al2o3 nanoparticles; especially with tio2 may be because of the delay period of titanium oxide is shorter than alumina which leads to complete combustion [10]. the best dose of nanoparticles is 25ppm for both types. where, tio2 and al2o3 reduce the emissions of co by 34.28% and 20.5% at 25ppm and 75% load respectively. fig. 3. variation of the carbon monoxide with titanium nanoparticles doses. td 313 diesel engine reg engine model four-cylinder, four-stroke engine type 3.666 l displacement 100 mm bore 110 mm stroke 17/1 compression ratio unit pump 26 mm diameter plunger fuel injection pump 23 btdc static injection timing 160o spray angle of nozzle 0.48 mm nozzle hole diameter 40mpa nozzle opening pressure sample density (kg/m3) dynamic viscosity *10-3 (kg/m.s) flash point & fire point oc calorific value k cal/kg cetane number diesel (d) 844.3 2.788 65-70 10941.08 51.8 d+al2o3 25 ppm 845.8 2.810 71-75 10943.23 52.1 d+al2o3 50 ppm 846.8 2.806 74-77 10946.33 53.1 d+al2o3100ppm 849 2.823 76-79 10949.41 53.9 d+tio2 25 ppm 852.4 2.780 73-76 10950.73 51.9 d+tio2 50 ppm 853 2.791 75-78 10955.78 52.7 d+tio2 100 ppm 853.8 2.825 78-82 10960.43 53.2 sadiq talal bunyan al-khwarizmi engineering journal, vol. 17, no. 1, p.p. 1319 (2021) 16 fig. 4. variation of the carbon monoxide with alumina nanoparticles doses. 3.2 nitrogen oxides (nox) emission the influence of nanoparticles doses level and types on nox emission for diesel fuel is shown in figure (4) and figure (5).the two figures reveal that the nox emission decreases with adding the dose 25 ppm of tio2 nanoparticles at all loads. while, the dose 25 ppm of al2o3 decreased nox emission at low loads. the expected reason for increased nox is high temperature with aluminum and the availability of oxygen. furthermore, the thermal conductivity of al2o3 is larger than tio2 by four times approximately. where, the thermal conductivity of tio2 and al2o3 are 9w/m.k and 40w/m.k respectively. the biggest decrease of nox emission with al2o3 and tio2 is 12.2% and 37.7% with no load at 25 ppm. fig. 5. variation of nitrogen oxide emissions (nox) with alumina nanoparticles doses. fig. 6. variation of nitrogen oxide emissions (nox) with titanium nanoparticles doses. 3.3 carbon dioxide emissions (co2) figure (6) and figure (7) shows the variation of carbon dioxide emission (co2) with nanoparticles doses for two types (tio2 and al2o3). these figures reveal that co2 emissions increase by increasing the dose of nanoparticles due to high thermal conductivity and the presence of oxygen in nanoparticles which in turn makes the combustion complete. the best increase was obtained in co2 emissions for tio2 and al2o3 by 1.75% and 2.27% at 75% load with 100 ppm respectively. the increasing of co2 emissions gives an indication to decrease co emissions. the overlap between the two curves of no-load with the curve with load with nanoparticles dose variation due to rich mixture at full load which in turn cause a reduction in co2 so the overlap occurred. fig. 7. variation of carbon dioxide emissions (co2) with titanium nanoparticles doses. sadiq talal bunyan al-khwarizmi engineering journal, vol. 17, no. 1, p.p. 1319 (2021) 17 fig. 8. variation of carbon dioxide emissions (co2) with alumina nanoparticles doses. 3.4 unburnt hydrocarbon (uhc) emissions the variation of unburnt hydrocarbon emissions (uhc) with different doses of nanoparticles for two types (al2o3 and tio2) is shown in figure (8) and figure (9).the two figures reveal that uhc emissions decrease by adding any dose of al2o3 nanoparticles at no load and it is increased with all other loads. while the additive tio2 nanoparticles decrease the emissions of uhc with all loads at all doses including no-load state. the expect reasons, that the equivalence ratio of tio2 is less than al2o3 , incomplete combustion of (d+ al2o3) and the size tio2 larger than al2o3 that gives a greater chance to atomize the large droplets of fuel during entering. finally, the biggest doze was 25 ppm for all loads. fig. 9. unburnt hydrocarbon emissions (uhc) with titanium nanoparticles doses. fig. 10. unburnt hydrocarbon emissions (uhc) with alumina nanoparticles doses. 4. conclusion the present paper focuses on the effect of adding alumina and titanium oxide to diesel fuel with variable doses on the emission characteristics based on the experimental results from present work. accordingly, the following conclusions are: 1. the best reduction of co at 25 ppm for both types. where tio2 and al2o3 reduce the emissions of co by 34.28% and 20.5% at 25ppm and 75% load respectively. 2. the adding of tio2 decrease nox emission by 37.7% at 25 ppm. while adding al2o3 increase nox emission except at low loads, where nox emission decreased by 12.2% at 25 ppm. 3. the adding of nanoparticles increase co2 emission for both types. the best increase achieves in co2 emissions for tio2 and al2o3 by 1.75% and 2.27% at 75% load with 100 ppm respectively. 4. the adding of tio2 decrease uhc emission by16.9% at 25 ppm and 75% load. while adding al2o3 increase uhc emission except with no load, where uhc emission decreased by 13.5% at 25 ppm. 5. references [1] amer abdullah, abed al-khadim m. hassan, mahmoud a.mashkour "the effect of bio-additives on the burning velocity and emission of liquid hydrocarbon fuel" ph.d.thesis dissertation department of mechanical engineering/university of technology, 2018. [2] rolvin d. "silvaa, binu k.g, thirumaleshwara bhat" performance and sadiq talal bunyan al-khwarizmi engineering journal, vol. 17, no. 1, p.p. 1319 (2021) 18 emission characteristics of a c.i. engine fuelled with diesel and tio2 nanoparticles as fuel additive" st joseph engineering college, vamanjoor, mangaluru 575028, karnataka, india,2015. [3] hamzah h. k., “experemental and numerical investigation of turbulent forced convection in a circular pipe with induced vibration”, ph.d. thesis dissertation department of mechanical engineering/ university of babylon, 2016. [4] mahendravarman r. d.b. sivakumar, p. sivakumar. “experimental study on performance and emission characteristics of a direct injection compression ignition engine with fe3o4 nanoparticles”. advanceds in natural and applied sciences. 10(4): pages 139-144, 2016. [5] s karthikeyan, a elango, a prathima "diesel engine performance and emission analysis using canola oil methyl ester with the nano sized zinc oxide particles" indian journal of engineering and material science, vol.21, pp. 83-87, 2014. [6] arul m.s. v,anand r.b., udayakumar m. “effects of cerium oxide nanoparticle addition in diesel and diesel-biodieselethanol blends on the performance and emission characteristics of a ci engine”. arpn journal of engineering applied sciences, vol 4, no.7, 2009. [7] nithin samuel, muhammed shefeek “performance and emission characteristics of a c.i engine with cerium oxide nanoparticles as additive to diesel" international journal of science and research vol.4 issue 7, 2013. [8] sukkar, k., karamalluh, a., & jaber, t. (2019). rheological and thermal properties of lubricating oil enhanced by the effect of cuo and tio2 nano-additives. alkhwarizmi engineering journal, 15(2), 24 33. https://doi.org/10.22153/kej.2019.12.002. [9] chaichan, m., hussein, r., & jawad, a. (2017). thermal conductivity enhancement of iraqi origin paraffin wax by nanoalumina. al-khwarizmi engineering journal, 13(3), 83-90. https://doi.org/10.22153/kej.2017.02.003. [10] s p venkatesan, p n kadiresh "influence of aluminum oxide nanoparticle additive on performance and exhaust emissions of diesel engine" international journal of applied engineering research issn 0973-4562 vol.10, number 3 pp. 5741-5749, 2015. [11] ajay k. "effects of cerium oxide nanoparticles on compression ignition performance and emission characrastics when using water diesel emulsion". thesis m.sc. dissertation department of mechanical engineering/ thapar university patiala147004, india july 2014. [12] yimin x., and qiang l., “heat transfer enhancement of nanofluids”, international journal of heat and fluid flow. vol. 21, pp.58-64, 2000. [13] hayder abed dhahad, sinan abdul-ghafar ali "experimental study on the effect of nanoparticle addition on the pressure at the start of ignition, maximum pressure and timing of maximum pressure" arpn journal of engineering and applied sciences, issn 1819-6608, vol. 14, no.8, 2019. ) 2021( 1319، صفحة 1، العدد17دجلة الخوارزمي الهندسية المجلم صادق طالل بنيان 19 دراسة تجريبية لتأثير الجسيمات النانوية المضافة لوقود الديزل على خصائص االنبعاث ** حسنالكاظم محمد عبد *صادق طالل بنيان الجامعة التكنولوجية/ العراق/ بغداد /قسم الهندسة الميكانيكية*،** sadiqtalal1993@gmail.com*البريد االلكتروني: akm1@yahoo.com**البريد االلكتروني: الخالصة ) النانوية كل على حدة إلى 2tio) النانوية وجسيمات أكسيد التيتانيوم (3o2alتم إجراء العمل التجريبي الحالي لفحص تأثير إضافة جزيئات األلومينا ( وقود الديزل للحصول على وقود النانو حوالي وقود الديزل على خصائص االنبعاثات. يبلغ حجم كل من األلومينا وأكسيد التيتانيوم اللذان تمت إضافتهما إلى ) جزء في المليون. تم خلط الجسيمات 100، 50، (25) وهي 2tio() و 3o2alنانومتر على التوالي. تم تحضير ثالث جرعات من ( ٢٥نانومتر و ٢٠ ص فوق ومعالج يدوي) كهربائي (خالط متجانس ميكانيكي معالج بواسطة الغاز زيت بوقود األلومنيوم النانوية أكسيد إضافة أن الدراسة كشفت وتي. )3o2al) التيتانيوم الغاز (2tio) وأكسيد أكسيد df2tio +) و (df3o2al +) إلى زيت ثاني انبعاثات المحرك مثل انبعاثات ) يحسن من خصائص و ٣٤٫٢٨الكربون بنسبة إلى ٢٠٫٥٪ بالنسبة ٪)+ df2tio( و)+ df3o2al( التوالي عند أج ٢٥على انبعاثات ثاني ، زادت المليون في سيد كزء جزء في المليون ، وانخفضت انبعاثات أكاسيد النيتروجين ١٠٠على التوالي عند )df3o2al +(و )df2tio +(٪ ل ٢٫٢٧٪ و ١٫٧٥الكربون بحوالي ٪ ١٦٫٩بحوالي )uhc(جزء في المليون وانخفضت انبعاثات ٢٥على التوالي عند )df3o2al +(و )df2tio +( كل من ٪ ل١٢٫٢٪ و ٣٧٫٧بحوالي جزء في المليون. ٢٥على التوالي عند )df3o2al +(و tio)df2 +( كل من٪ لـ١٣٫٥و this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 20, no. 3, september, (2024), pp. 7186 electromagnetic scattering properties and characterisation of sintered sic composite–based microwave spectrum alaa raad hussein*, thar m. badri albarody**and hajir mohammed ali*** *,***department of biomedical engineering, al‑khwarizmi college of engineering, university of baghdad, baghdad, iraq **mechanical engineering department, universiti teknologi petronas, seri iskander, perak, malaysia *email: alaa.r@kecbu.uobaghdad.edu.iq (corresponding author) **email dher.albarody@utp.edu.my ***email: hajir.m@kecbu.uobaghdad.edu.iq (received 2 november 2023; revised 5 april 2024; accepted 12 june 2024; published 1 september 2024) https://doi.org/10.22153/kej.2024.06.002 abstract silicon carbide (sic) is one of the most promising structural ceramic materials because of its excellent thermal and electromechanical properties. these properties are beneficial for cmc that enhances the performance of composites, especially those containing integrated nanoadditives. in this research, sic composites were fabricated from sic at three concentrations, zno and si. the magnetic properties of the mixtures were tested through vibratory sample monitoring. the green samples were sintered in a sintering furnace at 1600 °c in a nitrogen environment. the obtained composites have been tested and characterised using different techniques, including x-ray diffraction, surface morphology using fesem and network analyser, and the dielectric properties of the samples were tested. on the basis of the sintering environment, silicon nitride was detected in the composite because of the nitriding process along the composite. weak magnetic and absorbing properties were calculated for all the sic composites. the dielectric properties of a composite were considered high when the composite tended to be a reflector at a low frequency range and a transmitter as the frequency increased along the frequency band. therefore, the composite exerted a potential effect on the applications where shielding properties required in microwave range to prevent wave interference. keywords: sic nanocomposite: scattering parameter; vibratory sample monitoring of sic 1. introduction ceramic materials are considered non-metallic and inorganic materials used in many industrial sectors. nitride, carbide and oxide materials are classified as ceramics. possessing high densities and lightweight characteristics. ceramic composites utilised in electromagnetic (em) absorption applications are designed to serve two functions, withstanding harsh environments at rising temperatures and absorbing or transmitting the exposed em waves [1]. one of the most promising structural ceramic materials is silicon carbide (sic), which has excellent thermal and electromechanical properties and good mechanical characteristics [2]. certain materials are combined with sic to satisfy the dielectric properties of designated composites for structural composites. typically, additives alter the em properties of sic and turn it into a transparent, absorber or em-shielded structural composite [3]. complex permittivity determines whether sic composites have one of the scattering parameters. in theory, complex permittivity or relative permittivity (εr) is mainly divided into two parts: real (έ) and imaginary (ε′′) [4]. microwave-absorbing materials (mams) have been increasingly used in industrial applications because of worsening em pollution and radiation [5, 6]. in addition, sic ceramic composites are considered next-generation mams [7] and promising materials for stealth technologies and mailto:alaa.r@kecbu.uobaghdad.edu.iq mailto:dher.albarody@utp.edu.my mailto:hajir.m@kecbu.uobaghdad.edu.iq https://doi.org/10.22153/kej.2024.06.002 alaa raad hussein al-khwarizmi engineering journal, vol. 20, no.3, p.p. 7186 (2024) 72 military applications [8]. these composites reduce radar signatures during interactions with aircraft, tanks, targets and ships [9]. similarly, em interference reduction by microstrip back-radiation is common in civilian applications. sic composites in particular applications are required to be transparent rather than to have absorbing characteristics. this property is highly recommended for high em frequency applications particularly in the microwave range (x-band range; from 8.2 to 12.4 ghz), such as radars, radome, doppler, tv and telecommunication transmission [10]. the transparency of em waves can occur at a weak rl by obtaining low complex permittivity [11]. the values of εr are frequency dependent, showing varied responses to em. some studies on sic used silicon nitride as a start material to reduce em wave reflection and enables em waves to penetrate composites. xiao lin et al. [12] used sic and silicon nitride as porous media for em isolation; the composite was prepared by sintering at 1700 °c in a nitrogen atmosphere. instead of the sintering temperature, an oxidation process was utilised by zheng et al. [13] at 1100 °c to oxidise a si3n4–sic composite; the process reduced reflection when an interference action occurred between the em waves and the front or rear surfaces of the composite. the microstructure of composites is affected by rising temperature, which is visible in prominent x-ray diffraction (xrd) peaks or crystallography changes from amorphous to crystalline structure [14, 15]. wen et al. [6] observed changes in the sic composite from amorphous to a crystalline structure at elevated temperatures. this conversion was directly reflected on the dielectric properties of the composite that showed a ladder behaviour and increased the absorption performance of the sic composite. likewise, li et al. revealed that some fraction of the sic was transformed into sio2 because of oxidation at 1100 °c and the decreased xrd peak of sic. this decrease affected the behaviour of permittivity, increasing the value. ma et al. [16] examined heat treatments at 900 °c, 1400 °c, 1600 °c and 1800 °c. at 1800 °c; the process caused the composite to exhibit the largest degree of crystallisation, that is, the narrowest diffraction peak at (002), and directly reduced the interplanar spacing of the composite. these changes in crystallinity improved the polarisation of the material 1.7 times at temperatures above 1400 °c. a similar concept has been used but with different additives [17,21]. in this study, a composite with weak absorption properties was obtained by enhancing the dielectric properties of a sic-based nano reinforcement. 2. materials and method sic nanoparticles, silicon microparticles and zno nanoparticles with average particle size of 500, 1000–3000 and 10–30 nm, respectively, were used in the experiment. the preparation of powder and sampling of sic composites were conducted and explained in our last publication [22]. all fabricated samples were sintered at 1600 °c in a nitrogen environment in a horizontal tube furnace. sic and zno were pre-sintered at this temperature because the sintering temperatures of the two materials are higher than this temperature. si was melted and directly influenced by n2; however, this procedure nitrided the molten si that bonded to the bulk composite and distributed the nitriding effect all over the composite. the sintering temperature profile can be seen in fig. 1a. a low heating rate was adopted to reach the desired temperature. the dwell times for 800 °c and 1600 °c were 90 and 120 min, respectively [23], and the cooling rate was set according to the default of the furnace to reach the room temperature. the samples were characterised through vsm (fig. 1b). an x-ray diffractometer was used. for pan analysis, λ = 1.5405 nm, the cu-kα anode was used and the ratio between kα1 and kα2 radiation was 0.5. the angle of diffraction ranged from 10 to 90. the surface morphology was visualised using a ziess supra 55 vp scanning electron microscope, and the sintering of the samples and si3n4 was ensured. the complex permittivity and s11 and s21 scattering parameters were measured using a network analyser (ena, keysight e5071c) in a range of 8.2–12.4 ghz. alaa raad hussein al-khwarizmi engineering journal, vol. 20, no.3, p.p. 7186 (2024) 73 fig. 1. a) sintering temperature profile b) vsm testing machine 3. results and discussions 3.1.1. magnetic properties of the mixture the test is important to the examination of changes in the magnetic properties of sic, such as magnetisation saturation, coercivity, retentivity of magnetisation and squareness. if additives can affect the absorption properties of composites by affecting real and imaginary permeability, high magnetic properties can result in high absorption ability. thus, it was not used in this study. the lowest magnetic properties were used to ensure that no em was stored. fig. 2 shows the magnetic properties of sic composites at 70% sic with different additive concentrations. the magnetisation saturation of sic, which was 0.0047 emu/g, increased compared with that of the pure sic (approximately 0.0172 emu/g) [24]. the increase in magnetic saturation (ms) was due to the effects of zno and si because they have higher magnetic properties than sic. therefore, the amount of zno tended to increase the ms of sic from 70/20/10 to 70/10/20. the increase in the magnetisation saturation of sic can be attributed to the higher number of electrons in the electron shell of zn as compared with that in si. however, the increase in the ms of the sic composite was due to the effects of zno and si. the coercivity (hc), as mentioned in table 1, decreased gradually with increasing zno. this effect was due to the interaction of the dipole effect of the global composite. the interaction weakened when the amount of additives changed. the changes in the magnetic properties of sic were due to the jahn teller effect distortion of zno ions in the sic composite [25]. similarly, the retentivity (mr) and squareness values were extremely small and close to zero, indicating an extremely low magnetic property. this result can be attributed to the low magnetic characteristics of the composites that tend to lose the acquired magnetic field rapidly when it was reduced to zero. the value in table 1 shows the effect of additive concentration variation on the magnetic characteristics of sic even with little influence. the ms was considered extremely low in general, but variation in its magnetic values was due to the effects of zno and si. table 1 magnetic properties of sic composite at different additives concentration composite name ms (emu/g) hc (oe) mr (emu/g) squareness 70/10/20 0.0172 56.823 659.6 × 10−6 0.0383 70/15/15 0.0245 60.42 450.36 × 10−6 0.0192 70/20/10 0.0238 20.49 175.19 × 10−6 0.0072 a b sample holder sample alaa raad hussein al-khwarizmi engineering journal, vol. 20, no.3, p.p. 7186 (2024) 74 the mixture did not attain magnetisation saturation even when the magnetic field increased to the maximum value. this pattern of the hysteresis loop was due to the absence of dipole occurrence of the electron and indicates that the electron’s shell has completely filled and saturated the 1s, 2s and 2p orbits and tend to cancel any applied magnetic field [26]. fig. 2. magnetic properties of sic composites at 70% sic fig. 3 shows the effects of additive concentrations on the magnetic properties of sic. the soft magnetic was observed for all composites at 80% concentration, and maximum saturation magnetisation was observed at 0.0249 emu/g (table 2). this result was associated with the 80/10/10 composite when both additives were equal in concentration. this trend was similar to that of the previous sic concentration of the 70% sic sample. however, when the amount of the additive varied, the value of ms changed, indicating only a small difference between the maximum and minimum values. this result indicated that variations in em properties among additives were small, revealing weak magnetic properties that led to poor em absorption performance. coercivity was varied, gradually decreasing with increasing zno, and retentivity fluctuated as the amount of additives changed. however, owing to coercive force, sic can be classified as a soft magnetic material. alaa raad hussein al-khwarizmi engineering journal, vol. 20, no.3, p.p. 7186 (2024) 75 fig. 3. magnetic properties of sic composites at 80% sic table 2 magnetic properties of sic composite at different additive concentration composite name ms (emu/g) hc (oe) mr (emu/g) squareness 80/5/15 0.018 295.76 617.04 × 10−6 0.00342 80/10/10 0.0249 106.38 252.8 × 10−6 0.00102 80/15/5 0.0128 91.35 175.19 × 10−6 0.0072 in 90% sic, which had a large sic content, difference in ms was marginal (fig. 4 and table 3). the maximum value was found in the 90/2.5/7.5 composite and was close to the maximum values of 70% and 80% sic. the reduction in ms was due to the increase in sic content. the formation of s-shape in fig. 4 gradually disappeared when the si value decreased and plateaued, as in the 90/7.5/2.5 composite. however, the effect of additive on sic afforded sic magnetic properties, especially when the concentration of sic was low, as in 70% sic. consequently, the diamagnetic behaviour of sic was extremely strong because of its bond, forcing the composite to remain in its insulation area. many parameters, such as shape anisotropy, structure and crystallinity, can influence the magnetic properties of nanostructured materials [27]. this kind of influence is related to electron density in the orbital and how it is saturated with energy to accept addition energy. this influence was implied by variations in ms and coercivity for all tested mixtures. the unpaired electron resulted in diamagnetic properties represented by the extremely low ms. low magnetisation led to low permeability, reducing the ability of a material to interact with the magnetic part of the em wave. reduction in permeability greatly influenced the absorption of the total composite, which showed increased transmission because of low magnetic conductivity. alaa raad hussein al-khwarizmi engineering journal, vol. 20, no.3, p.p. 7186 (2024) 76 table 3 magnetic properties of sic composite at different additives concentrations composite name ms (emu/g) hc (oe) mr (emu/g) squareness 90/2.5/7.5 0.0183 202.02 499.03 × 10−6 0.0272 90/5/5 0.0168 291.74 68.06 × 10−6 0.00404 90/7.5/2.5 0.0119 181.35 453.77 × 10−6 0.0379 the vsm results of the selected sic composites explained the strong diamagnetic properties of sic, especially when the concentration reached the maximum value in the composite. secondly, si had a stronger effect than zno as an additive enhancing the magnetic properties of sic. furthermore, all composites showed extremely low magnetic behaviour and can be classified as soft magnetic materials [28]. the low degree of magnetisation, retentivity and squareness indicated that the composite gained a diamagnetic property that affected its interactions and the formation of the magnetic field of the em wave. the vsm results indicated that the powder mixture resulted in a weak absorption property of the emw spectrum. fig. 4. magnetic properties of sic composites at 90% sic 3.2. xrd analysis of sintered composites the xrd peaks of composite sintered at 1600° are shown in fig. 5. notably, all the sic composites were affected by the surrounding inert n2 gas. the sharp peaks observed for sic, zno and si3n4 confirmed that the composite had a crystalline structure without any amorphous molecules. owing to sintering environment, silicon nitride si3n4 was detected along the diffraction angles in which all the si3n4 peaks were matched with the alaa raad hussein al-khwarizmi engineering journal, vol. 20, no.3, p.p. 7186 (2024) 77 reference no. icsd (98-064-4683) and (98-0164619) as a hexagonal crystalline structure. the peaks were in good agreement with the findings in the literature [12, 29-31]. owing to high temperatures, si and zno reacted individually. however, si was more influenced because the temperature exceeded its melting point (1440 °c) and it reacted with the inert gas (n2). thus, the composition of si3n4 did not influence zno or sic. zno has a hexagonal structure (wurtzite structure) with stable microstructural properties at high temperatures [32, 33]. variation in the amount of si in the original composites was observed, and the low intensity of si3n4 was detected in the 90/7.5/2.5 composite. the good distribution of si3n4 in the composite was indicated by the detected peaks along the diffraction angles. em properties can be enhanced by varying the distribution of si3n4 and attenuating the microwave energy. moreover, enhancement can be achieved by increasing the permittivity value determining the shielding effect. the effect of shielding decreased with si concentration in the 90/7.5/2.5 composite when a low amount of si was added to the sic composite. fig. 5. xrd of the sic composites at 1600°c 3.3. morphology of the sintered samples fig. 6 shows the sample morphology of the sic composite. the distribution of the molten si in all particles exposed to high temperatures was uniform. thus, the liquid-phase silicon that formed si3n4 interconnected sic and zno particles [34]. this behaviour was due to continuous network formation during sintering, producing a solid sic composite structure and increasing the densification of the particles. fig. 6. a) fesem of the sintered sic composites at 1600°c, b) magnification of (a) showing the silicon nitride. si3n4 a b alaa raad hussein al-khwarizmi engineering journal, vol. 20, no.3, p.p. 7186 (2024) 78 3.4. em responses properties of the sintered samples em properties determine how much a composite respond to exposed emw. a response can have different shapes (absorption, reflection or shielding and transparent properties). all these characteristics are influenced dramatically by the fabrication process, types and number of additives and the number of phases facing the incident emw. therefore, the sintering environment (inert gas n2) was dispersed in the molten particles, thereby generating a combination that proportionally influenced the wave propagation inside the composite. this reaction generated a compound considered transparent to microwave and increased the electron charge mobility of the composite particles [29, 35]. 3.4.1. dielectric properties when em waves, especially microwave, are incident on a material, three mechanisms may occur and cause the polarisation of composite particles: electronic, ionic and orientation and space charge polarisation. however, these mechanisms enhance the charge mobility of an electron and increase the real part of permittivity or conductivity. therefore, three different phases resulted in a specific transparent property because of the existence of oxide and nitride in the composite. these compounds altered the dielectric properties of sic and turned it into a conductive material to a material with microwave properties. the complex permittivity of the samples with 70%, 80% and 90% sic concentration are shown in fig. 7. sic plays a major role in the reduction of permittivity because it is considered a dielectric material when it is pure. this effect comes from the orientation of its crystalline structure after exposure to a high temperature. however, even at a high temperature, it did not change the inherent em properties of sic because no major conversion turning sic into a different phase occurred. meanwhile, variation in em response between composites in each individual group was attributed to the additives. the molten silicon formed si3n4, and the sintered zno added additional bond force to the composite, considerably influencing increment in polarisation. this added force resulted in a maximum value of 16.21, which corresponded to 12.4 ghz for the 70/10/20 composite, as observed in fig. 7a. this modification corresponded to the high si3n4 content. the permittivity gradually decreased to 8.99 at 9.43 ghz in the 70/20/10 composite, where the maximum value of zno existed, which allowed for microwave propagation. fig. 7b shows the imaginary part of permittivity, and the largest value was obtained from the 70/10/20 composite. this result indicated that the electrical conductivity of the composite was at its maximum value, and the broad peaks shown in the figure were related to large polarisation relaxation. hence, the dissipated energy at this level was extremely weak compared with that of the 70/20/10 composite, where no obvious resonance peaks appeared. this increment in ε′′ value was associated with an increase in the temperature, enhancing the mobility charge of the electron by accelerating response. fig. 7c shows the 80% sic composites. the low amount of zno was associated with increase in permittivity. thus, 80/5/15 had the highest permittivity values, which gradually decreased to a minimum at 80/15/5. when zno concentration was low, the composites showed abundant broad resonance peaks, compared with 80/15/5. the width of these resonance peaks increased with frequency, as in the 80/15/15 composite, where both additives had similar percentage, but then disappeared in the 80/15/5 composite. the decrease in the number of peaks was attributed to the low concentration of si3n4, which reduced polarisation. this behavioural change in resonance positions did not match when the composites contained 90% sic, as shown in fig. 7e. the mixing ratios shared similar resonance peaks at 10.12 ghz. in principle, high-value permittivity is typically associated with low impedance values [36]. therefore, sintering at 1600 °c caused si to melt, zno to sinter and sic particles to pre-sinter. consequently, the incident wave faced a new phase of polarisation because of change in the crystalline structure, especially in si, which resulted in phase change because of phase sintering. the imaginary permittivity of all the composites sintered at 1600 °c tended to be frequency dependent, and the energy storage increased with frequency. this behaviour demonstrated that the internal structure was stable and contained a conductive network [3, 19]. the imaginary permittivity part and electrical conductivity increased because of zno. as a result, the nitriding samples increased the conductivity of the composite through the phase transformation of si from a solid form to a liquid form after si combined with nitrogen. however, alaa raad hussein al-khwarizmi engineering journal, vol. 20, no.3, p.p. 7186 (2024) 79 the results were close to that in a previous study. [29]. fig. 7. complex permittivity of 90% sic composites at 1600°c a, c, e) real part permittivity, b, d, f) imaginary part permittivity. 3.4.2. scattering performance em wave scattering can be explained in three parts: reflection, transmission and absorption. reflection occurred at the two surfaces of the bulk material, the external and other surface oppose to the exposure surface (internal). meanwhile, the transmitted and absorbed waves can propagate throughout a material. some waves penetrate the internal surface, whereas some are reflected inside the composite, dissipate gradually and are converted into thermal energy. fig. 8 shows the reflection (s11) performance of all the samples sintered at 1600 °c. the effect of additives varied the s11 value, especially at high concentration ratios. zno and si3n4 exhibited good response to em waves in terms of reflection (0.71–0.26). their effect was clearly differentiated by their different concentration ratios in the sic composites. in the 90% sic (fig. c), no considerable differences were observed between alaa raad hussein al-khwarizmi engineering journal, vol. 20, no.3, p.p. 7186 (2024) 80 the different additive concentrations because of the high amount of sic. this trend demonstrated that a low concentration of additives results in low variations. thus, charge mobility is considered approximately equal in 90% sic. at a high frequency, the composite was unable to store microwave energy and tended to transmit from the other side. the transmission coefficients were computed from s21 (fig. 9) for the 1600 °c samples. transparency increased with frequency for all cases [37, 38]. this increment showed that the composites were frequency dependent. the introduction of zno and si to the composite played a crucial rule in wave propagation. fig. 8. reflection coefficient of the sintered samples a) 70% sic, b) 80% sic and c) 90% sic fig. 9. transmission coefficient of the sintered samples a) 70% sic, b) 80% sic and c) 90% sic 3.4.3. absorption evaluation the values of reflection loss (rl) are shown in fig. 10. the composite had an extremely weak absorption properties for all mixing ratios. furthermore, slight difference in the frequency of the absorption was observed at different frequency bands. a composite can be considered to have good absorption properties when the rl exceeds −10 db, in which 90% of energy is stored inside the composite and reflected until it is converted into heat and dissipates to the environment. a composite associated with this property is called a microwave-shielding material. in this study, shielding was not achieved because of the nature of silicon nitride, which tends to transmit most of the energy. by contrast, zno has an oxide element that enables wave energy to pass through particles without storing it. the lowest rl obtained for the 70/20/10, 80/15/5 and 90/2.5/7.5 composites were −6.699 db at 12.06 ghz, −5.76 db at 10.9 ghz and −5.36 at 11.7 ghz, respectively, which are in good agreement with those obtained in a previous study [39]. the high ε′ values of the composites at this level showed that the material is a reflector and transmitter rather than an absorber, and the microwave energy hardly infiltrated the material. alaa raad hussein al-khwarizmi engineering journal, vol. 20, no.3, p.p. 7186 (2024) 81 fig. 10. rl of composites sintered at 1600°c a) 70% sic, b) 80% sic and c) 90% sic furthermore, si3n4 affected the absorption coefficient by promoting the propagation of the transmitted wave and minimising internal scattering due to porosity. the large gap between the ε′ and ε′′ lowered the impedance mismatch along the frequency band. this observation was ascribed to a balance between the two values and enabled the composite to absorb energy. this balance was not associated with a specific material and mainly depended on the orientation of the dielectric properties, enhancing the particles and increasing the ε′′ value as permeability increased. 3.4.4. variable thickness measurement (vt) the scattering parameters of the 70/20/10 composite with varying thickness are shown in fig. 11. the selected composite was based on the increased transmission response. the thickness increased the shielding effect and reflection. however, the responses of the sic composites varied as reflection gradually decreased with increasing thickness. the highest reflection factor was obtained in the 2 mm-thick sample, which had the lowest transmission rate. conversely, a rapid decrease in reflection was observed along the x-band at 4 mm thickness, which was sufficient for the minimum reflation of 0.1 at 12.4 ghz. low reflection led to high transmission or absorption properties. the 4 mm-thick composite exhibited rapid increase in transmission coefficient because of the large effect of porosity associated with composites fabricated at 1600 °c. porosity increased with thickness, which can be generated in the global composite because of the introduction of silicon nitride. however, differences among the 2.5, 3.0 and 3.5 mm-thick samples were small. the 3 mmthick samples had the same thickness as the standard samples used in the previous measurement and showed a compatible response of reflection and transmission, as stated previously. the thickness of the composite had a direct proportional relationship with complex permittivity and permeability. thus, a small thickness can negatively affect transmission because of reduced attenuation, which occurred because of the small distance between the external and internal surfaces. thus, internal scattering was reduced because of the lag in electron charge motion. alaa raad hussein al-khwarizmi engineering journal, vol. 20, no.3, p.p. 7186 (2024) 82 fig. 11. transmission and reflection coefficients of vt samples the exposed microwave on the surface has to attenuate inside a material, particularly in dielectric materials. this form of attenuation is mainly determined using destructive interference. 𝑓𝑚 = 𝑐 4𝑑 √|𝜇𝑟𝜀𝑟|, …(1) where fm is the peak frequency and d is the absorber thickness. the peak frequency is proportionally attributed to complex permittivity and permeability, and thickness has an inverse relationship with fm. hence, the calculation of rl shown in fig. 12 for all samples had no considerable absorption properties and was compatible with the scattering parameter. the minimum value of rl was associated with the 2 mm thickness and had a value of −6.49 at 9.8 ghz. poor absorption properties were observed in the samples with other thickness. fig. 12. rl of the vt samples 4. conclusion sic composites were fabricated with different additive concentrations through sintering. all the sintered samples produced silicon nitride, which was detected along the xrd diffraction angles and confirmed the reaction between the fused si and n2. hence, the reaction between nitrogen and the molten silicon showed good correlation. si3n4 exerted a considerable effect on the interfacial polarisation of microwave. the dielectric coefficient increased to a maximum value (16.21) at a mixing ratio 70/10/20, in which the maximum si content was found in the composite. the 70/20/10 composite had the lowest permittivity (7.8) because of the effect of zno on the bulk composite and low concentration of si. in terms of scattering parameters, the maximum value of reflection of the 70% sic was higher than the maximum values of the 80% and 90% sic. the calculation of the transmission line theory indicated poor absorption in all the sintered samples. variation in the thickness of the highest transparency coefficient samples showed deviations in transmission and reflection. thickness of 2 mm produced the highest reflection factor in all materials. meanwhile, the lowest reflection (0.10 at 12.4 ghz) was observed at a thickness of 4 mm. the vt results indicated that the composite exhibited high response to microwaves in terms of variable thickness. notably, the designated composite had moderate transparent properties suitable for random application, allowed high microwave frequencies to penetrate the composites and protected the microwave instrument safe from the effects of harsh environments. alaa raad hussein al-khwarizmi engineering journal, vol. 20, no.3, p.p. 7186 (2024) 83 acknowledgement the author is grateful to the department of mechanical engineering universiti teknologi pertronas, perak-malaysia, for their technical and financial support under grant number urif0153aa-b91, the research and development centre staff for their em support at universiti teknologi petronas and biomedical engineering department at al‑khwarizmi college of engineering for their support and help in the publication of this paper. references [1] v. tomar, "5 multiscale modeling of the structure and properties of ceramic nanocomposites," in ceramic nanocomposites, r. banerjee and i. manna, eds., ed: woodhead publishing, 2013, pp. 153-182. 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(2024) 71-86، صفحة 3، العدد20مجلة الخوارزمي الهندسية المجلد عالء رعد حسين 86 الملبد sicخصائص التشتت الكهرومغناطيسي وتوصيف طيف الميكروويف القائم على مركب ***هاجر محمد علي ،**ذر محمد بدري البارودي ،*عالء رعد حسين ، بغداد، العراققسم هندسة الطب الحياتي، كلية هندسة الخوارزمي، جامعة بغداد*،*** بتروناس التكنولوجية، سيري إسكندر، بيراك، ماليزياقسم الهندسة الميكانيكية، جامعة ** alaa.r@kecbu.uobaghdad.edu.iq :البريد االلكتروني* dher.albarody@utp.edu.my :البريد االلكتروني** hajir.m@kecbu.uobaghdad.edu.iq :البريد االلكتروني*** المستخلص متازة. هذه الخصائص م(، فهي تتمتع بخصائص حرارية وكهروميكانيكية sicواحدة من أكثر مواد السيراميك الهيكلية الواعدة هي كربيد السيليكون ) . تم siو zno من ثالثة تركيزات مع sicلتعزيز أداء المركب خاصة عند إضافات النانو المدمجة. في هذا البحث، تم تصنيع مركب cmcمفيدة ل درجة مئوية 1600لتلبيد عند ا(. تم تلبيد العينات الخضراء في فرن vsmالهتزازية )اختبار الخواص المغناطيسية لجميع المخاليط باستخدام مراقبة العينة ا ورفولوجيا السينية، وم األشعة في بيئة النيتروجين. تم اختبار جميع المركبات التي تم الحصول عليها وتوصيفها باستخدام تقنيات وتوصيفات مختلفة مثل حيود لمركب بسبب اسيليكون في كة الختبار الخصائص العازلة للعينات. بناء على بيئة التلبيد، تم اكتشاف نيتريد ال، ومحلل الشبfesemالسطح تمت باستخدام ئص العازلة عالية . تعتبر الخصاsicعملية النترجة على طول المركب. من ناحية أخرى، تم حساب الخصائص المغناطيسية واالمتصاصية لجميع مركبات لى أثير محتمل عتركب له كون عاكسا في نطاق التردد المنخفض ونافذ كلما زاد التردد على طول نطاق التردد. ولذلك، فإن المحيث يميل المركب إلى أن ي التطبيقات التي تتطلب خصائص التدريع في نطاق الموجات الدقيقة لمنع تداخل الموجات mailto:alaa.r@kecbu.uobaghdad.edu.iq*البريد mailto:alaa.r@kecbu.uobaghdad.edu.iq*البريد mailto:dher.albarody@utp.edu.my**البريد mailto:dher.albarody@utp.edu.my**البريد mailto:hajir.m@kecbu.uobaghdad.edu.iq***البريد mailto:hajir.m@kecbu.uobaghdad.edu.iq***البريد 1. introduction 2. materials and method 3. results and discussions 3.1.1. magnetic properties of the mixture 3.2. xrd analysis of sintered composites 3.3. morphology of the sintered samples 3.4. em responses properties of the sintered samples 3.4.1. dielectric properties 3.4.2. scattering performance 3.4.3. absorption evaluation 3.4.4. variable thickness measurement (vt) this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 19, no. 2, june, (2023) p. p. 2638 removal of malachite green from aqueous solution using ficus benjamina activated carbon-nonmetal oxide synthesized by pyro carbonic acid microwave khatab emad talib* sami d. salman** *,**department of biochemical engineering/ al-khwarizmi college of engineering/ university of baghdad/ baghdad/ iraq *email: khattab.i@kecbu.uobaghdad.edu.iq **email: sami.albayati@gmail.com (received 20 december 2022; accepted 8 march 2023) https://doi.org/10.22153/kej.2023.03.002 abstract activated carbon derived from ficus binjamina agro-waste synthesized by pyro carbonic acid microwave method and treated with silicon oxide (sio2) was used to enhance the adsorption capability of the malachite green (mg) dye. three factors of concentration of dye, time of mixing, and the amount of activated carbon with four levels were used to investigate their effect on the mg removal efficiency. the results show that 0.4 g/l dosage, 80 mg/l dye concentration, and 40 min adsorption duration were found as an optimum conditions for 99.13% removal efficiency. the results also reveal that freundlich isotherm and the pseudo-second-order kinetic models were the best models to describe the equilibrium adsorption data. keywords: ficus benjamina activated carbon; microwave irradiation; taguchi experiment. 1. introduction freshwater in particular and water, in general, have become more necessary during the past few years as a dearth of fresh water has been observed largely, as the expansion of the industrial sector in general and human expansion has led to the scarcity of water and increased demand for fresh water. [1,[2] 2]. industrial expansion and human expansion have increased the need for clean water as this expansion has increased the proportion of effluents and increased the use of fertilizers and other substances that adversely affect the purity and cleanliness of the water and cause significant water pollution [3][4]. in industries in general, effluents and other wastes are often dumped without being processed to water sources from rivers and lakes, where they have been contaminated, where they need to be chemically treated and used again industrially [5,6]. in the last decade, the treatment of sewage has been of great importance, as dyes that change the color of the water are one of the chemicals that industrial discharges release. [7,8]. since the presence of the least concentration of toxic dyes in water has serious consequences for the environment, dyes are often disposed of in the pharmaceutical, cosmetic, food, textile, leather, printing, and paper industries. [9,10]. textile industries contribute to the largest pollution of dyes due to their ineffectiveness because dye molecules are not fully related to fabrics or tissues, where the majority of dye residues in textile industries are disposed into the environment[11,12]. dyes disposed of from industries in general and textile industries, in particular, have attracted great attention because of the effects they cause, as there are a large number of harmful chemicals that make up dyes that are presented as liquid residues to factories, and these chemicals will contaminate mailto:sami.albayati@gmail.com https://doi.org/10.22153/kej.2023.03.002 khatab emad talib al-khwarizmi engineering journal, vol. 19, no. 2, p.p. 3648 (2023) 27 water and cause damage to the aquatic environment[13,14]. dyes affect photosynthesis processes where they block sunlight and prevent it from penetrating the layers of water to reach aquatic organisms and plants, in addition to the impact of these toxic chemicals resulting from dyes on human and animal health. [15,16]. annually large quantities and different types of dyes are produced and used in industry in general. mg dye is an organic dye with cationic basic which is often used in paper and pharmaceutical industries, leather and textile industries, and food industries as food coloring, and food additives and also used in other applications such as its use as a fungal and parasitic pesticide in the field of aquaculture as well as anthelminthic[17,18]. in addition to all these uses for dyeing mg, many studies have revealed the dangerous and toxic effects of the use of mg dye, as it is toxic to aquatic organisms because of the presence of strong metal ions, which tend to increase their toxicity to aquatic organisms as well as show that they affect plants where the roots of plants absorb water contaminated with mg dye where they affect metabolism. teratological, carcinogenic threats, and mutagenic threats are considered untreated mg dye from one of their causes, affecting the food chain by entering and accumulating dye molecules in the food chain, leading to the aforementioned threats to mammalian cells[19]. other unwanted impacts incorporate side effects on the liver, and spleen, heart harm, skin injuries, lessening in fertility rates, growth rate, and development. despite this, they too act as a tumor promoters in liver cells by diminishing malachite green, expanding its perseverance, and actuating apoptosis and tumor. hence, there's prime significance within the removal or treatment of mg color profluent due to its poisonous impacts on the biological system[20,21]. there are many methods used to remove dyes and these methods used are coagulation, electrochemical oxidation, membrane filtration, rhizoremediation, ozonation, reverse osmosis, flocculation, precipitation, adsorption, phytoremediation, and ultrasonication [22,23] of all the methods mentioned, the adsorption method is the most appropriate and has attracted researchers among the previous methods to use it in the purification of unprocessed water for the following reasons in terms of operational cost and removal of complex organic structures as well as in terms of the least productive of byproducts [24]. a nonreactive, equilibrium technique that includes particle accumulation on the two-section interface is known as adsorption [25]. being feeeffective, easy operation, and quite efficient, the adsorption method is extensively used for the removal of poisonous dyes from the tainted environment [26 27]. also, the overall performance of adsorptive separation improves with the traits of the adsorbent [28]. properties together with the terror group, floor area, nontoxicity, reusability, and a fee of the adsorbent are of paramount significance withinside the dye expulsion from business effluents[29,30]. different adsorbents exploited for mg dye adsorption consist of nylon microplastics[31], almond gum [32], litchi peel biochar [33], calcium alginate nanoparticles [34], avena sativa hull [35], brewer’s spent grain[36], nanocomposites[37], and clayey soil [38]. in a few cases, the expensiveness of activated carbon organized from various substances limits its utilization withinside the dye elimination technique. hence, little research was done on the soil as an adsorbent, for example, floor soils [39] and laterite soil [40]. this study focused on the use of activated carbon derived from ficus binjamina agro-waste synthesized by pyro carbonic acid microwave method and treated with silicon oxide (sio2) to produce ac/sio2 composite precursor to remove mg produce dye from aqueous solution. batch adsorption was utilized to investigate the effect of three factors with four variables of concentration of dye, mixing time, and the amount of adsorbent on the removal efficiency. 2. experimental 2.1. adsorbate preparation malachite green (mg) dye stock at various concentrations was prepared from a standard solution of mg dye by dissolving 1 g of mg dye in 1 l of distilled water. the standard solution was diluted with distilled water to achieve the desired dye solution concentrations (20 – 80) mg/l. the various concentration of dye was determined using uv-visible spectroscopy with a calibration curve as illustrated in figure 1. khatab emad talib al-khwarizmi engineering journal, vol. 19, no. 2, p.p. 3648 (2023) 28 fig.1. calibration curve of mg concentration. 3.1 experimental design in this study, three independent factors with four levels of initial dye concentration, mixing time, and adsorbent dosage were selected for design experiments as shown in table 1, whereas and taguchi method with 16 experiments was generated by statistica 12.5 software to investigate their impact on the quality of mg dye adsorption as shown in table 2. table 1, factors with their levels of taguchi design method. parameter factor level mg concentration (ppm) x1 20 40 60 80 mixing time (min) x2 20 40 60 100 dose of ac (g/l) x3 0.10 0.20 0.30 0.40 table 2, number of runs proposed by the taguchi method ci (ppm) time (min) dosage (g/l) 20 20 0.1 20 40 0.2 20 60 0.3 20 100 0.4 40 20 0.4 40 40 0.3 40 60 0.2 40 100 0.1 60 20 0.2 60 40 0.1 60 60 0.4 60 100 0.3 80 20 0.3 80 40 0.4 80 60 0.1 80 100 0.2 3.1 adsorbent preparation and characterization the composite adsorbent was prepared (acsio2) was prepared from ficus benjamin twigs collected from the gardens of the university of baghdad. the twigs were firstly washed with water to remove dust and dried overnight in an oven at 100 degrees celsius. the dried twigs were crushed and sieved through a mesh sieve (720 micrometer1mm), then the sample was impregnated at high temperatures, sio2 powder (30nm) was impregnated in 60% h3po4 impregnated time of 4 hr, and impregnation ratio of 3:1 (acid/sample) the impregnated material filtered to remove excess acid and poured into a conical flask equipped in 700-watt power of microwave oven for activation under nitrogen flow of 150 cc/min with 20 min time of activation. the produced activated carbon was washed with hot water to remove the acid residue the washing water was tested for ph 6.5-7, and the activated carbon dried at 105˚c for 24 hr. in addition, the composite activated carbon was prepared by impregnating 25 g of ac in 250 ml of an aqueous suspension containing 1.25 g of sio2 powder, and the resulting mixture was heated at 80 oc for 5 hours with 300 rpm stirring. the product was filtered, and the solid was washed with distilled water until the color in the residual liquid disappeared, then the solid product dried for 24 hours at 120 c, to obtain the desired adsorbent for the mg dye removal. sem, and bet analyses were used to undertake the qualitative investigation of ac before adsorption. 3. result and discussion 3.1 batch experimental studies a batch experiment was proposed using the taguchi method as described before and the response as experimental removal efficiency is illustrated in table 3. the batch experiments were carried out to evaluate the factor's effects and their interaction on the removal efficiency of mg. 250ml erlenmeyer flask containing the necessary adsorbent (0.10.4) g/l of ac-sio2 and (20-80) ppm of mg dye solution. the solution was agitated on a temperature-controlled mixer for a specified contact period (20-100) min. the mixture of acsio2 and dye solution was filtered after specific time intervals to remove the solid from the solution. ultraviolet-visible spectroscopy was used to determine the equilibrium concentration of mg khatab emad talib al-khwarizmi engineering journal, vol. 19, no. 2, p.p. 3648 (2023) 29 dye. the mg adsorption capacity and efficiency were determined in equations 1 and 2. qe = (co – ce)v/m …(1) re% = (co – ce)/ co …(2) where co and ce are dye initial and equilibrium concentrations (ppm), respectively; qe is the equilibrium capacity of mg (mg/g); v is the volume of mg solution (l); m is the mass of acsio2 g). table 3, taguchi method for a batch design experiment ci time dosage re% 20 20 0.1 94.82% 20 40 0.2 95.39% 20 60 0.3 95.96% 20 100 0.4 96.53% 40 20 0.4 97.69% 40 40 0.3 97.98% 40 60 0.2 97.98% 40 100 0.1 97.41% 60 20 0.2 98.46% 60 40 0.1 98.65% 60 60 0.4 98.65% 60 100 0.3 98.27% 80 20 0.3 99.11% 80 40 0.4 99.13% 80 60 0.1 98.99% 80 100 0.2 98.70% the final empirical formula (model) of mg removal efficiency ac-sio2 (y) was generated by the taguchi method as shown in equation 3, which was well fitted with experimental data with r2 = 98.949556. 𝑌 = 𝑏0 + 𝑏1𝑋1 + 𝑏2𝑋2 + 𝑏3𝑋3 + 𝑏12𝑋1𝑋2 + 𝑏13𝑋1𝑋3 + 𝑏123𝑋1𝑋2𝑋3 + 𝑏11𝑋1 2 + 𝑏22𝑋2 2+𝑏33𝑋3 2 …(3) where y is the removal efficiency of mg, b0, b1, b2, and b3 are linear coefficients, b12, b13, and b123 are second-order interaction terms, and b11, b22, and b33 are quadratic terms of each factor x1, x2, and x3 are the coded phrases for mg concentration, mixing duration, and ac-sio2 dosage. tables 4 show the estimated values of the model coefficient, standard error of each model term, and p-value. it is obvious from the table that all coefficients have a substantial effect on model accuracy because their p-values are less than 0.05. table 4, model coefficients, standard error, and terms pvalues for removal mg by ac-sio2 coefficient estimate standard error t-value df=1 p-value lo.conf limit up.conf limit b0 0.904901 0.005904 9 0.011287 0.890456 0.919346 b1 0.001784 0.000163 1 0.016568 0.001386 0.002183 b2 0.000349 0.000111 1 0.013976 0.000078 0.000620 b3 0.062459 0.030699 1 0.022429 -0.012660 0.137578 b12 -0.000001 0.000157 1 0.025932 -0.000001 -0.000001 b13 -0.000286 0.000321 1 0.016033 -0.001073 0.000500 b123 -0.000006 0.000739 1 0.0221875 -0.000006 -0.000006 b11 -0.000010 0.000218 1 0.0186909 -0.000010 -0.000010 b22 -0.000002 0.000954 1 0.0198723 -0.000002 -0.000002 khatab emad talib al-khwarizmi engineering journal, vol. 19, no. 2, p.p. 3648 (2023) 30 3.2 adsorption isotherm model several adsorption isotherm models can be used to understand the behavior of adsorbate molecules at a solid-liquid contact. langmuir (langmuir 1916) examined adsorption data at a constant temperature using equation (4) to assume that adsorption is conducted as monolayer adsorption on homogeneous sites. whereas freundlich (freundlich 1925). examined adsorption data at a constant temperature using equation (5) assuming that adsorption was conducted as multilayer adsorption on heterogeneous sites. 1 𝑞𝑒 = 1 q𝑚 + 1 𝑘𝐿 𝑞𝑚 𝑐𝑒 …(4) ln 𝑞𝑒 = ln 𝑘𝑓 + ( 1 𝑛 ) ln 𝐶𝑒 …(5) where qe (mg/g) is the equilibrium adsorption capacity, and qm (mg/g) is the full monolayer adsorption capacity. ce (mg/l) represents the equilibrium mg concentration, kl (l/mg), kf (l/mg) and 1/n are constants. the adsorption behavior of mg on ac-sio2 was represented by langmuir and freundlich models as shown in figures 2 and 3. it’s noted from these figures that the adsorption followed the freundlich model (r2 = 0.9906) which implies that the mg adsorption process occurred on the assumption of multilayer adsorption on the heterogeneous surface of ac-sio2. this behavior is similar to that reported by [41]. table 5 summarizes the langmuir and freundlich coefficients that fitted with experimental data for malachite green (mg) adsorbed on ac-sio2. fig. 2. langmuir isotherm model for mg adsorption by ac-sio2. fig. 3. freundlich isotherm model for mg adsorption by ac-sio2. table 5, freundlich and langmuir coefficients for mg adsorption on ac-sio2 3.3 kinetics of adsorption the adsorption process mechanism of mg on ac-sio2 can be represented by several kinetic models. the pseudo-first-order and pseudosecond-order models as well-known models to observe the mechanism of the adsorption process as physisorption or chemisorption are represented by equations 6 and 7. ln(𝑞𝑒 − 𝑞𝑡) = ln 𝑞𝑒 − 𝑘1𝑡 …(6) 𝑡/𝑞𝑡 = (1/𝑘2𝑞𝑒 2) + (𝑡/𝑞𝑒) …(7) where qe (mg/g) is the equilibrium adsorption capacity, qt (mg/g) is the adsorption capacity, t (min) is the time of adsorption, kl (l/min) and k2 (mg/g.min) are constants. figures 4 shows the plot of ln (qe − qt) versus time of adsorption (t) as a pseudo-first-order model as given in equation (5) with the value of model (r2 = 0.9458) whereas figure 5 shows the plots of t/qt versus time of adsorption (t) as pseudo-secondorder model as given in equation (6) with the value of model (r2 = 0.9657). it’s noted that the adsorption process is well-fitted with a pseudolangmuir freundlich kl (l/mg) qm (mg/g) r2 kf (mg/g ) n r2 0.09551 65.7696 0.9851 2.2305 1.3927 0.9906 khatab emad talib al-khwarizmi engineering journal, vol. 19, no. 2, p.p. 3648 (2023) 31 second-order model which means that the mechanism of the adsorption process complied with chemisorption. this mechanism is similar to that reported by [42]. the kinetic parameters for two kinetic models and correlation coefficients were summarized in table 6. fig. 4. plots of pseudo-first-order adsorption kinetics of mg adsorption mechanism. fig. 5. plots of pseudo-second-order adsorption kinetics of mg adsorption mechanism table 6, the kinetic parameters for two kinetic model and correlation coefficients. pseudo-first order pseudo-second order qe, exp (mg/g) k1 (1/min) qe,cal (mg/g) r2 k2 (g/mg min) qe, cal (mg/g) r2 47.4356 0.00017 25. 641 0.9548 0.07707 49.9 0.9981 3.4 adsorbent characterization 3.4.1. characterization using bet brunaure-emmett-teller technique (usa, horiba, sa-900 series) was used to determine the specific surface area of the activated carbon sample based on liquid nitrogen adsorptiondesorption isotherm at temperature (77k), and the data obtained are summarized in table 7. table 7, bet analysis of ac sample weight 0.0255 [g] standard volume 9.779 [cm3] dead volume 15.21 [cm3] equilibrium time 0 [sec] adsorptive n2 apparatus temperature 0 [c] adsorption temperature 77.000 [k] saturated vapor pressure 84.772 [kpa] adsorption cross section area 0.162 [nm2] khatab emad talib al-khwarizmi engineering journal, vol. 19, no. 2, p.p. 3648 (2023) 32 bet plot vm 15.454 [cm3(stp) g-1] as,bet 672.65 [m2 g-1] c 66.879 total pore volume (p/p0=0.990) 0.5889 [cm3 g-1] mean pore diameter 35.02 [nm] the bet surface area of activated carbons treated with sio2 produced from ficus benjamin was found to be relatively high, with the optimal surface area being 672 m2/g. the adsorption crosssection area of the sample is 0.162 nm2 in the nanopore range. the average pore width was determined to be 35.025 nm, which corresponds to iupac categories of nanoporous materials within the given range [43]. 3.4.2. characterization using sem a scanning electron microscope was used to analyze the surface shape and topographical features (sem). the generated photographs are three-dimensional and accurately depict the surface form. the energy dispersive x-ray spectrophotometer is used to examine the ac/sio2 precursor elements (eds). sem-eds analysis was performed using tescan, vega iii, czech republic. figure 6 shows the morphology of the ac/sio2 precursor surface is not smooth and not homogeneous in appearance, with somewhat visible pores with a layered structure and spongy nature and various pores sizes and shapes. these holes' variability in sizes and shapes arose from the breakdown and volatilization of non-carbonaceous material in feedstock, and the pores generated as a result of chemical and physical activation provide dyes a good chance of being adsorbed. the white spot on the surface of the precursor is referred to sio2 which increases the surface area without blocking porosity, the presence of sio2 makes a thin layer on the surface of the ac which increases the curvature leading to an increase in the surface area. fig. 6. sem for ac. 3.4.3 characterization using ftir fourier transform infrared spectroscopy was utilized to determine the functional groups that occur on the surface of both ficus benjamin and ac/sio2. the infrared spectra were examined using a fourier transform infrared spectrophotometer (ir affinity-1 shimadzu, japan). figure 7 (a, b) show the ftir of ac used in the research. khatab emad talib al-khwarizmi engineering journal, vol. 19, no. 2, p.p. 3648 (2023) 33 (a) (b) fig. 7. a) ftir for ac/sio2, b) ftir for ficus benjamin wood. ficus benjamin and ac's ftir spectra, as seen in fig. 7 (a and b). it is obvious that the ftir spectra of ac have lower intensities than the spectrum of ficus benjamin and that many of ficus benjamin's peaks have vanished. this evanescence is caused by the dissolution of chemical bonds during the h3po4-impregnation, which then causes the carbonization process to eliminate and liberate a variety of volatile molecules [44]. the ac ftir spectra revealed four peaks at 3425, 1647, 1554, and 1415 cm-1. it is possible that the hydroxyl group of the o-h stretching vibration appears at 3425 cm-1 [45]. the peak of about 1554 cm-1 could be attributed to c=c stretching vibrations in the aromatic rings, and the band around 1647 cm-1 to cc stretching vibrations in the alkyne groups [46]. while the 1415 cm-1 peak shows the presence of co stretching vibrations in alcohols, phenols, acids, ethers, or esters [47]. 3.5. surface analysis response the effect of mg concertation, time of mixing, and dose of adsorbent on removal efficiency at ph = 4 and mixing speed = 400 rpm are illustrated in 3d response surface plots as shown in figure 8 and 9. figure 8 depicts the effect of various initial concentrations of mg dye (20, 40, 60, and 80) mg/l with an adsorbent dose ranging from (0.1 0.4) g/50 ml. it’s noted from this figure that the adsorption of mg dye increase as the adsorbate concentration increases until it reaches to surface saturated with adsorbate concentration (80 mg/l) khatab emad talib al-khwarizmi engineering journal, vol. 19, no. 2, p.p. 3648 (2023) 34 which means that the adsorbent has more free active sites on its surface to facilitate adsorption [19]. likewise, as shown in figure 9, the effect of mg concentration with various mixing time (20100) min, as the time of mixing increased the removal efficiency increased before becoming constant at 80 mg/l which mean that the active site of the adsorbent saturated with mg particles [41]. fig. 8. removal efficiency of mg versus concentration and adsorbent dose. fig. 9 removal efficiency of mg versus concentration and time of mixing. 4. conclusion the present research revealed that ficus binjamina agro-waste can effectively be used as a raw material for the preparation of activated carbon pyro carbonic acid microwave method silicon oxide (sio2) as composite material for the removal of mg dye from aqueous solutions. the adsorption process followed the freundlich and pseudosecond-order kinetic models which explained that the adsorption may involve multilayer adsorption behavior with interactions between the adsorbate molecules and the availability of the adsorbent sites than the adsorbate concentration. pesticides in khatab emad talib al-khwarizmi engineering journal, vol. 19, no. 2, p.p. 3648 (2023) 35 solution. the experiment conditions with the method of activation were optimized using the experimental design methodology and the results were analyzed with the statistica 12.5 software. the results of the adsorption studies show that the equilibrium of adsorption was reached in around 40 minutes, and the best adsorbent was discovered to be 80 mg/ l at ph 6 and a mixing speed 400 rpm. according to the desorption investigations, the malachite green was preferably adsorbed on the carbon surface in the presence of silicon oxide. as a 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(2023) 26-38، صفحة 2، العدد19مجلة الخوارزمي الهندسية المجلد خطاب عماد طالب 38 المنشط من الملكيت األخضر من المحلول المائي باستخدام أكسيد الكربون الالفلزيصبغة إزالة الذي تم تصنيعه بواسطة الميكروويف مع حمض الكربونيك نبات الفيكس بنجامينا سامي داود سلمان** خطاب عماد طالب* جامعة بغداد *،**قسم الهندسة الكيميائية االحيائية/ كلية الهندسة الخوارزمي/ khattab.i@kecbu.uobaghdad.edu.iq*البريد االلكتروني: sami.albayati@gmail.comي:**البريد االلكترون الخالصة والُمصنَّع بواسطة طريقة الميكروويف مع حمض الفسفوريك الزراعية تم استخدام الكربون المنشط المشتق من المخلفات الزراعية لنبتة الفيكس بنجامينا تم دراسة ثالثة عوامل من المحلول المائي. )mg ( لتعزيز قدرة الكاربون المنشط المتزاز لصبغة الملكيت األخضر )2sio (ومعالجته بأوكسيد السيليكون خضر من المحلول المائي منها تركيز الصبغة، وقت الخلط وكمية الكربون المنشط. بأربعة مستويات للتحقق من تأثيرها على كفاءة أزالة الصيغة الملكيت األ ٪. وقد 99.13دقيقة كشرط أمثل للوصول الى كفاءة اإلزالة بحدود 40ومدة امتصاص مجم / لتر، 80تركيز صبغة لتر،جم / 0.4أظهرت النتائج أن جرعة امتزازكانت أفضل النماذج لوصف بيانات الثانية الدرجةفروندليتش فضال عن النماذج الحركية الزائفة من نموذج التوازن الحراري كشفت النتائج أيًضا أن .التوازن دعن األخضرصبغة الملكيت mailto:sami.albayati@gmail.com (microsoft word 22-31\343\325\330\335\354) al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 16, no. 1, march, (2020) p. p. 2231 the influence of process variables for milling sculptured surfaces on surface roughness mustafa mohammed abdulrazaq department of production engineering and metallurgy / university of technology email: mustafaalneame@yahoo.com (received 8 october 2019; accepted 19 january 2020) https://doi.org/10.22153/kej.2020.01.001 abstract increasing the variety of products that are being designed with sculptured surfaces, efficient machining of these surfaces has become more important in many manufacturing industries. the objective of the present work is the investigation of milling parameters for the sculptured surfaces that effecting of surface roughness during machining of al-alloy. the machining operation implemented on c-tek cnc milling machine. the influence of the selected variables on the chosen characteristics have been accomplished using taguchi design approach, also anova had been utilized to evaluate the contributions of each parameter on process outcomes. three strategies of tool path (zig, zig-zag and follow periphery), and three levels of spindle speeds (1700, 2200 and 2700 rpm), with three feed rates (200, 400 and 600 mm/min). the results showed that low surface roughness values produced with the zig-zag strategy, higher speeds (2700) rpm and lower feed rates (200) mm/min. the analysis of variance approach anova showed that the strategy of tool paths was the most affecting variables on surface roughness with percentage of contribution of (42.25 %). keywords: sculptured surface, surface roughness, anova, tool path strategy. 1. introduction milling sculptured part surfaces is different from milling the regular surface parts, the cause of that is, it could be traced back to the differences of sculptured and regular surfaces nature especially in the freedom of sculptured surface modeling [1]. the main characteristics of machined sculptured surfaces are the shape and the actual designing parameters. they strongly depend on the parameters for the operation of the surface generation [2]. milling sculptured surface in carried out with two stages: rough milling and finishing. the first stage of cutting used for removing the large amount of work-piece material and leaves slightly oversized material of the part that removed in the next stage. finishing is the processes that remove the remaining material from the roughing of the sculptured surfaces work piece and gives final dimensions for machining the desired parts. the result surfaces are produced with a numbers of scallop heights. thus that lead to the surface roughness on the machined parts and it is important to be investigated for improving the surface quality for the final product [3]. surface roughness of engineering parts is very important variable, where the quality of any machined part depending on it. detailed assessment is essential for carrying out precisely and analyzing the micro geometry of surfaces [4]. the roughness of surfaces for the manufactured part is one of the important characteristics to insure the quality of the products. in 2013 jatin & sharma [5] investigated the effecting of a various cutting variables (feed rate, cutting speeds depth of cuts) in end mills on the mustafa mohammed al-khwarizmi engineering journal, vol. 16, no. 1, p.p. 2231 (2020) 23 surface roughness. the calculations have done by utilizing taguchi designing method. in addition to the s/n ratio, also anova have illustrated to clarify the impact of variables through the result data. their studies has been illustrated in milling process for hardened die steel h-13, using flat-end cutter with four flue of solid carbide for finishing process. the results show that surface roughness decreases at the increasing of cutting speeds. simunovic (2013) [6] studied the influence of milling parameters (number of revolution, feed rate and depth of cut) on the surface roughness of aluminum alloy. a statistical (regression) model has been developed to predict the surface roughness by using the methodology of experimental design. central composite design is chosen for fitting response surface. also, numerical optimization considering two goals simultaneously (minimum propagation of error and minimum roughness) has been performed throughout the experimental region. it has been found that feed rate and number of revolutions, as well as the interaction between the feed rate and number of revolutions are significant. zeljkovic m., et al. (2017) [7]: identify optimum machining parameters on surface quality of sculptured parts. the effect of various machining process parameters such as machining strategy, feed, depth of cut and spindle speed on roughness of surfaces through three-axis end-mill of sculptured parts have been studied by performing a number of experiments constructed according to standard taguchi’s l9 orthogonal array design matrix. grey relational analysis method was used to find the optimal machining process parameters and analysis of variance was carried out to find the significance and contribution of each machining parameter on performance characteristics. 2. taguchi experimental design method taguchi method is depending on that the machined parts quality must be computed by the deviation amount from the required value. he takes into consideration not only the process mean, but also by the variation magnitudes or "noise" created with manipulating inputs parameters or operation variables. this technique is depending on two groups; a unique kind of matrix called "orthogonal array (oa)", the columns include a number of tests depending on the no. of levels of controlling parameters, and (s/n) the signals to noise ratio [8,9]. the expression ‘signal’ indicating of the required of the output characteristics values "mean" and the expression ‘niose’ indicating of unrequired values. s/n ratios calculation is varying based on objectives functions, i.e., a characteristics amount. designing the method using minitab16 program as follow: 3. variance analysis the experimental work results could be investigated by (anova) variance analysis to discover the effecting of machining variables (tool path strategies, spindle speeds and feed rates) on surface roughness through the entire process. in the analysis, the ratio between mean square errors and residual called fratio and it utilized for determining the importance of a parameter. f ratio correspondent to 95% reliable levels in calculations of the operation variables. p values are the report of importance levels of each parameter (appropriate and inappropriate) [10, 11]. 4. sculptured surface representation in this paper bezier technique illustrated for representing the proposed study surface. using the sixth order degree with seven control points to the entire surface for representing the required surface of the product, and the equation of the proposed bezier surfaces is: tt bb wpmumwuf =),( …(1) =bm                       − − −− −− −−− −−− 0000001 0000066 0000150315 00020600632 001560900615 06306060306 1615321561 ]1[ 23456 uuuuuuu = ]1[ 23456 uuuuuuw = where u and w are the vectors of surface parameters, mb is the bezier basis function matrix stat doe taguchi create taguchi design mustafa mohammed al-khwarizmi engineering journal, vol. 16, no. 1, p.p. 2231 (2020) 24 that represents the bezier surface and (p) is the vertex information matrix (control point) with (49) control points. the bezier basis functions are derived from bernstein polynomial for the parametric coefficients [12]. the creation of cad modeling has been implemented utilizing bezier technique depend on the algorithm through selecting the required control point matrices using matlab software, and transferring the cad data to ug-nx software for generating the tool paths and post processing that required for implementing the machining process. the cad module, where profile of the curves generating the surfaces is modeled-using matlab and then transferred to the ugs-nx9-through txt data-exchanges file to view the required shape. after the construction of the bezier surface converted to a series of curves using iso-parametric conversion scheme figure (1) shows the proposed surface using matlab software and the part after transferring the cad data to ug-nx. the data of the curves have been represented and saved in a single matrix of (n x 3), where n is the number of rows which is equal to n =1+ 1/δu, where δu is the increment of the independent parameter. each matrix is saved as (txt) file and exported to the ug-nx program. after importing the curves in ug-nx software, a skinning procedure for these curves have been implemented to accomplish the final shape of the surface. (a) (b) fig. 1. (a) the proposed surface using matlab, (b) transferring the cad data to ug-nx software. 5. tool path generation after the completion of representing cad models, it is followed by the tool path generation for designed part utilizing ug-nx software. there are several steps had to be taken for the creation of the actual tool paths, the process has two phases, first one is creating tool paths for roughing, where the requirement must be chosen for this stage, such as (machining method, tool geometries, tools diameter, strategy of tool paths …etc.). the second phase is creating tool path for finish machining. in finishing process the side step value of the tool paths is very small compared to roughing process three deferent strategies have been implemented in this work; zig, zig-zag and follow periphery strategies. figure (2) shows the three illustrated types of tool path strategy. (a) mustafa mohammed al-khwarizmi engineering journal, vol. 16, no. 1, p.p. 2231 (2020) 25 (b) (c) fig. 2. deferent strategies of tool paths (a) zig, (b) zig-zag, (c) follow periphery. 6. machines and tools the experiments have been conducted on 3axis cnc milling machine which is existed in workshop training center in university of technology, with work piece dimension (40 x 40) mm and thick (40) mm. this operation needs some accessories and experimental setup, the main elements that must be used in the milling machine can be divided into the following elements: 6.1. machine of milling process figure (3) shows the 3-axis cnc machine of milling operation type (c-tek) with model (km80d) that used in the machining process of the samples which machined in the present work. fig. 3. cnc c-tek milling machine. 6.2. cutting tool flat-end milling tools (ø 10 mm) dia., with four flutes and flute length equal to (40 mm) of high-speed steel (hss) utilized for rough milling phase, and ball-end milling tools (ø 12 mm) dia. for finishing. the cutting tools are shown in figure (4). fig. 4. cutting tools. 6.3. work piece al-7024 alloy work piece is chosen to be milled. the chemical composition was tested in the "central organization for standardization and quality controls". tables (1) and (2) show the chemical composing and the mechanical properties of the work piece respectively. flat-end tool d=10 ball-end tool d=12 mustafa mohammed al-khwarizmi engineering journal, vol. 16, no. 1, p.p. 2231 (2020) 26 table 1, chemical composition of aluminum 7024. table 2, mechanical properties of aluminum 7024. 6.4. designing of experiments the designing of experimental tests using taguchi approach had a great influence on the required experimental tests numbers. accordingly, the experiments of machining required an appropriate design. the overall number of machining experimental tests is (9) experiments, on the basis of (3) levels and (3) variables (33). the levels of milling parameters are listed in table (3). table 3, cutting variables. no parameter level 1 level 2 level 3 1 spindle 1700 2200 2700 2 speed zig zig-zag follow periphery 3 strategy 200 400 600 the final distributional division of the experimental tests and the level of each experiment are clarified on table (4) depending on the taguchi experimental design method: table 4, experimental design of work. no. spindle speed (r.p.m) tool path strategy feed rate (mm/min) 1 1700 zig 200 2 1700 zig-zag 400 3 1700 follow periphery 600 4 2200 zig 400 5 2200 zig-zag 600 6 2200 follow periphery 200 7 2700 zig 600 8 2700 zig-zag 200 9 2700 follow periphery 400 6.5. implementation the machining process the milling process is done in two processes; rough machining and finishing, removing materials take place on a rapid way as much as possible in rough machining. in this process, a higher material removal rate is used for minimizing the process time. rough machining in most cases illustrated in parallel levels of layers accessing to the exact depths. the quality of the final surfaces is not reliable, where that layers removed by subsequent process (finishing process). figure (5) shows the samples after machining. si % fe% cu % mn% mg% cr% ni% 0.18 0.41 2.17 0.19 1.57 0.092 0.014 zn% ti% ga % v % pb % other al% 4.91 0.039 0.012 0.009 0.072 0.134 90.21 ultimate tensile strength (mpa) tensile yield strength (mpa) elongation to failure (%) modulus of elasticity (gpa) hardness brinell 469 324 20% 73.1 231 mustafa mohammed al-khwarizmi engineering journal, vol. 16, no. 1, p.p. 2231 (2020) 27 fig. 5. samples after machining. 6.6. surface roughness inspection pocket-surf, the portable gauge of surface finish (mahr federals patented). the gauge is a pocket sized, which has a suitable economical price, integral portable device, provides a tracing for surface roughness measurement through widely surface types. the instrument probe has a durable cast-aluminum structure to obtain long time accurately dependable surface roughness inspection shown in fig (6-a). since the proposed surface in the present work is sculptured surface, the measurement process of the surface roughness for such surfaces needs to make the instrument inclined with suitable angles which make the tracer parallel to the surface, so a special holder has been used to fix the instrument, this holder has the ability to move up and down with inclined motion of multi angles to ensure tracing the surface geometry in parallel way as it illustrated in fig (6-b). (a) (b) fig. 6. (a) pocket-surf gauging instrument, (b) measurement process using the movable holder. 7. result and discussions table (5) represents the experimental results of machining the al-alloy samples and the surface roughness according to the orthogonal array table 5, the values of measured roughness no. speed strategy feed rate surface roughness 1 1700 zig 200 1.12 2 1700 zig-zag 400 1.06 3 1700 follow periphery 600 1.336 4 2200 zig 400 1.048 5 2200 zig-zag 600 1.096 6 2200 follow periphery 200 1.056 7 2700 zig 600 1.24 8 2700 zig-zag 200 0.776 9 2700 follow periphery 400 1.26 7.1. effect of tool path strategies and feed rate on surface roughness the figure (7) shows the effecting of tool path strategy and the feed rate on surface roughness, the graph clarified that increasing the feed rate give a high values of the surface roughness and the reason of that belong to increasing the mustafa mohammed al-khwarizmi engineering journal, vol. 16, no. 1, p.p. 2231 (2020) 28 temperature of cutting and the reason of that belongs to increasing the friction between the tool and the metal surface leading to overheat states, and thus will oxidize the outer surface and producing a rough surface finish. on the other hand the better surface finish obtained using zigziag tool path strategy among them. fig. 7. effect of the strategy and feed rate on surface roughness. 7.2. effect of spindle speed and tool path strategies on surface roughness figure (8) shows the effects plot of machining factors (spindle speed and the tool path strategy) on surface roughness, it can be noted that increasing the spindle speed values decreasing the surface roughness, where increasing the revolutions of the cutter will repeat the passing of cutter edge on closer regions removing the numbers of scallop heights. on the other hand the maximum values of surface roughness obtained by using the follow periphery strategy, while the lower values obtained using zig-zag strategy. through testing multi tools for implementing the finishing stage, it found that using ball-end tool with (12 mm) in diameter for generating tool paths giving lower values of scallop heights which leads to less surface roughness in machined surface in case the diameter doesn't exceed the lowest value of concavity that existing in the surface to prevent occurring the gauging areas. beside, implementing the follow periphery strategy for generating the required tool path for the surfaces will effect on machining time, where it takes shorter time than using zig and zig-zag strategies. and the reason of that belongs to the distribution of the tool paths, where in this type of strategy the cutter path tracing the regions of the required geometry and its not necessary to reach the regions that doesn’t need to be machined, contrariwise with other types that may reach to regions doesn’t need for machining just to complete the straight line along the path. fig. 8. effect of spindle speed and strategy on surface roughness. 7.3. analysis of variance the experimental results are analyzed by using analysis of variance (anova) to determine the effect of machining parameters on the surface roughness, surface roughness as the dependent variable, tool path strategy, spindle speed and feed rate as independent variables. the f ratio value of 2.19 for the tool path strategy is greater among the parameters (see table 6). therefore, the most influential parameter is tool path strategy (42.3 %) for minimum surface roughness, and the next significant parameter is feed rate with (41.2%). finally, the spindle speed has the smallest influence with (8.57%). mean value of surface roughness ra and signal to noise ratio are shown in figures (9 and 10). these figures clarifies the effect of process parameters on the output roughness, it can be seen that increasing the feed rate increasing the roughness, where the best surface roughness obtained with (200 mm/min). on the other hand, the lower spindle speeds increase the surface roughness values, where heights ra given with (1700 rpm). and the best surface roughness obtained using zig-zag tool path strategy. mustafa mohammed al-khwarizmi engineering journal, vol. 16, no. 1, p.p. 2231 (2020) 29 table 6, analysis of variance for roughness 2 7 0 02 2 0 01 7 0 0 1 . 2 0 1 . 1 5 1 . 1 0 1 . 0 5 1 . 0 0 z ig -z a gz igf o llo w p e r ip h e ry 6 0 04 0 02 0 0 1 . 2 0 1 . 1 5 1 . 1 0 1 . 0 5 1 . 0 0 s p in d le s p e e d m ea n of s ur fa ce r ou gh ne ss s t ra t e g y f e e d ra t e m a i n e f f e c ts p l o t f o r m e a n s d a ta m e a n s fig. 9. main effect plot for means of roughness. 2 7 0 02 2 0 01 7 0 0 0 . 0 0 . 5 1 . 0 1 . 5 2 . 0 z ig z a gz igf o llo w p e r ip h e r y 6 0 04 0 02 0 0 0 . 0 0 . 5 1 . 0 1 . 5 2 . 0 s p in d le s p e e d m e an o f s n r at io s s t r a t e g y f e e d r a t e m a i n e f f e c t s p l o t f o r s n r a t i o s d a ta m e a n s s ig n a lto n o is e : s m a lle r is b e t t e r fig. 10. main effect plot for means of roughness. from figure (11) it can be seen that the tool path strategy the most significant parameter affecting on surface roughness, this is because the strategy of motion of tool is responsible for generating the final surface. then the feed rate, while the spindle speed is the less effective parameter on the process among the other variables. fig. 11. the percentage of contribution of the three parameters on the process. source of variance dof sum of squares variance v f ratio p (%) spindle speed 2 0.0181 0.009 0.28 8.57 strategy 2 0.0894 0.045 2.19 42.3 feed rate 2 0.038 0.019 2.10 41.2 error ,e 2 0.118 0.059 8.02 total 8 2.07 100 mustafa mohammed al-khwarizmi engineering journal, vol. 16, no. 1, p.p. 2231 (2020) 30 8. conclusions to summarize the concluded influences that deduced from these experiments could be sum up in: • the best combination of machining factors for giving the minimum surface roughness (ra) among (tool path strategies, spindle speed and feed rate) is: (zig-zag tool path, 2700 rpm and 200 mm/min) respectively. • tool path strategy has the highest effect with (42.25%) the feed rate and the spindle speed has the smallest influence on the surface roughness. • using ball-end tool with (12 mm) in diameter for generating tool paths, will give lower value of scallop heights which leads to less surface roughness in machined surface in case the diameter doesn't exceed the lowest value of concavity that existing in the surface to prevent occurring the gauging areas. • implementing follow periphery strategy for generating the required tool path for the surfaces will effect on machining time, where it takes shorter time than using zig and zigzag strategies. 9. references [ 1] j. paulo davim, "machining of complex sculptured surfaces", department of mechanical engineering university of aveiro, springer-verlag london limited, 2012. [ 2] b. mikó, j.beňo, and i. maňková, "experimental verification of cusp heights when 3d milling rounded surfaces", acta polytechnica hungarica, vol. 9, no. 6, pp. 101-116, 2012. [ 3] a. helleno, k. schützer, "contribution for the manufacturing of sculptured surfaces with high-speeds based on new methods of tool path interpolation", 20th international congress of mechanical engineering, gramado-rs, brazil, november, pp. 15-20, 2009. [ 4] a. r. silva, a. x. morales, l.a. moraleshernandez and f. g. funes, "characterization of the surface finish of machined parts using artificial vision and hough transform", national polytechnic institute of mexico and autonomous university of queretaro mexico, 2012. [ 5] k. jatin and pankaj sharma, "effect of machining parameters on output characteristics of cnc milling using taguchi optimization technique", international journal of engineering, business and enterprise applications, vol. 6, pp. 64-67, 2013. [ 6] k. simunovic, "predicting the surface quality of face milled aluminium alloy using a multiple regression model and numerical optimization", measurement science review, vol. 13, pp. 265–272, 2013. [ 7] s. tzeng yihfong, "parameter design optimization of computerized numerical control turning tool steel for high dimensional precision and accuracy", material and design. vol.27, pp. 665-675, 2006. [ 8] h. shukry, and a. m. laith , “studying parameters of edm based micro-cutting holes using anova”, eng. &tech. journal, vol.31, no.15, pp. 2876-2887, (2013). [ 9] k. wissam, “feasibility development of incremental sheet metal forming process based on cnc milling machine”, phd. thesis, university of technology, 2009. [ 10] a. s. bedan, and h. a. habeeb “an investigation study of tool geometry in single point incremental forming (spif) and their effect on residual stresses using anova model”, al-khwarizmi enginering journal, vol. 14, no.2, pp. 1-13, 2018. [ 11] m. mustafa, s. k. ghazi and m. q. ibraheem, “investigation the influence of spif parameters on residual stresses for angular surfaces based on iso-planar tool path”, al-khwarizmi engineering journal, vol. 15, no.2, pp. 50-59, 2018. [ 12] r. goldman "bezier curves and surfaces" in an integrated introduction to computer graphics and geometric modeling, taylor and francies, pp. 379-384, 2009. )2020( 2231، صفحة 1العدد ، 16دجلة الخوارزمي الهندسية المجلم مصطفى محمد عبد الرزاق 31 تأثير متغيرات عملية التفريز لالسطح الحرة على الخشونة السطحية مصطفى محمد عبد الرزاق الجامعة التكنولوجية / هندسة االنتاج والمعادن قسم mustafaalneame@yahoo.comemail: الخالصة لتشغيل عينات من االلمنيوم. عملية التشغيل على الخشونة السطحية ان الهدف البحث هو التحقيق في مدى تأثير متغيرات عملية التفريز لالسطح الحرة تأثير هذه المتغيرات التي تم تحديدها تمت بأستخدام طريقة تاكوشي، كذلك تم استخدام تقنية تحليل العناصر .c-tekنفذت على ماكنة تفريز مبرمجة نوع ثالث و )، follow peripheryو zig ،zig-zagألختبار نسبة مساهمة كل متغير وتأثيره على العملية. ثالث استرتيجيات من مسارات العدد وهي ( ). النتائج اظهرت دقيقة ملم /٦٠٠و ٤٠٠، ٢٠٠. اضافة الى ثالث معدالت للتغذية ()دورة بالدقيقة ٢٧٠٠و ٢٢٠٠، ١٧٠٠مستويات من السرع الدورانية ( ٢٠٠( معدل تغذية واقل )دورة بالدقيقة ٢٧٠٠ة (واعلى سرعة دوراني zig-zagعند استخدام استراتيجية ان اقل قيم للخشونة السطحية تم الحصول عليها .%) ٤٢٬٢٥بنسبة مساهمة وصلت الى (.ان طريقة تحليل العناصر اظهرت ان استرتيجيات مسار العدد هي االكثر تأثيرا من باقي المتغيرات ملم/دقيقة) <4d6963726f736f667420576f7264202d20e3c7e1df20e6dacfe4c7e420e6cce6e1ede6d334332d203533> al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 16, no. 3, sptember, (2020) p. p. 4353 uav control based on dual lqr and fuzzy-pid controller malik m. a. al-isawi* adnan j. attiya** julius o. adoghe*** * ,**department of mechatronics engineering/ al-khwarizmi college/ of engineering/ university of baghdad ***department of mechanical and aerospace/carleton university/ canada *email: malik@kecbu.uobaghdad.edu.iq **email: adnan@kecbu.uobaghdad.edu.iq ***email: osemudiamenadoghe@cmail.carleton.ca (received 6 february 2020; accepted 23 augusta 2020) https://doi.org/10.22153/kej.2020.08.001 abstract this paper presents the design of a longitudinal controller for an autonomous unmanned aerial vehicle (uav). this paper proposed the dual loop (inner-outer loop) control based on the intelligent algorithm. the inner feedback loop controller is a linear quadratic regulator (lqr) to provide robust (adaptive) stability. in contrast, the outer loop controller is based on fuzzy-pid (proportional, integral, and derivative) algorithm to provide reference signal tracking. the proposed dual controller is to control the position (altitude) and velocity (airspeed) of an aircraft. an adaptive unscented kalman filter (aukf) is employed to track the reference signal and is decreased the gaussian noise. the mathematical model of aircraft has been (cessna 172) presented. the stability and robustness of the system have been verified in a simulation experiment. keywords: uav, longitudinal controllers, fuzzy-pid, lqr, aukf. 1. introduction unmanned aerial vehicles (uavs) have been a popular research subject over the last years. these vehicles have been used in civilian applications and military missions, including search, rescue, and atmospheric research [1, 2]. studies have been carried out on small uavs because of the low costs of the system and their effectiveness in special missions. autonomous uav like helicopters are one of the most popular robotic platforms because they are easy to control for vertical take-off and landing as well as for stationary flight [3, 4]. the choices are many possible methodologies that can be used uav control. sliding mode control is an efficient, robust control method that widely used in the control of many complex systems [5]. however, chattering is a big drawback of sliding mode control [6]. the most popular controller in the past is a proportional-integral-derivative controller (pid). analytical methods are used to tune the conventional structure of the pid controller [7]. an approach to control, stabilization, and disturbance rejection of the attitude subsystem of a quadrotor. a self-tuned pid is used to design the controller of the autopilot based on the longitudinal motion (altitude, and speed), and lateral motion (heading angle) of aerosonde uav [8]. the authors in [9,10] presented a method to guide and control a system-based vision system. they introduced a fuzzy logic controller is designed to be compared with the self-tuned pid controller also they used aukf to estimate the state of the system and reduce the effect the noise on it. in [11], a stable gain scheduling pid controller is developed based on the grid point concept for nonlinear systems. the autopilot controller has a high accuracy of the tracking path, and the robustness with respect to environmental disturbances and especially winds. the small uavs are sensitive to wind disturbance, since its magnitude may be comparable to the uavs speed [12]. the author malik m. a. al-isawi al-khwarizmi engineering journal, vol. 16, no. 3, p.p. 4353 (2020) 44 [13] presents self-tuning pid controller method based on neural network is proposed. this method single layer neural network to get the pid gains. the fuzzy pid controller is developed to improve the performance of the longitudinal motion (pitch control) of the aircraft [14]. this paper focuses on how to combine both advantages of fuzzy control and pid control so that the dynamic performance, far away from the design point, can be improved [15]. the longitudinal model of the unmanned aerial vehicle (uav) is established and control using fuzzy pid [16]. the control strategies include the velocity loop (inner loop) and the height loop (outer loop). the authors [17] present a comparison between different controllers used with a dynamic model of a quadcopter platform. these controllers are an itae tuned pid, a classic lqr controller, and a pid tuned with an lqr loop. the conventional lqr method present in [18] has effectively solved the problems that fixed-wing uav is disturbed by air current easily and has poor flight stability. the longitudinal control for the flying wing uav based on lqr can make the flying wing uav achieves satisfactory longitudinal flying qualities [19]. the authors presented a studying the control of the vertical moving for uav under pid, lqr, fuzzy control, and self-tuning fuzzy pid. they have investigated the controller's effectiveness on the state of vertical motion uav [20]. a plqr controller is presented to investigate the longitudinal motion control of uav. this controller is explained and compared with pid and lqr controllers [21]. the robust control is presented in [22]. a cmmac (classical multiple model adaptive control) has implemented for tracking the performance of quadrotor helicopter against the linearization model error and uncertainties. a robust controller on an aerial manipulator is presented [23]. this controller can track the error in the external disturbance and also, the stability is proved. the main objective of this paper is to introduce a more robust controller schema and a more distinctive gain tuning procedure. the controller must provide a reference signal for altitude and airspeed. a dual fuzzy pid and lqr controllers are proposed in this work to analyze the effectiveness of the control designs. the corresponding evaluation of the system performance is presented. 2. mathematical model of a uav the equation of motion for a uav can be divided into longitudinal and lateral movement. the platform of cessna 172 can show in fig. 1. the only motion control considered in this paper is longitudinal. this model can be obtained based on the linearization of the equations in steady level flight. the longitudinal dynamics are the response of the aircraft along the pitch axis, as expressed in the following eqn. 1 [24, 25]: ��� � �� � �� …(1) where � � � � � ���� 0 0 0 0 � � ��� � 0 0 0 0 � �� ��� 0 0 0 0 0 1 0 0 0 0 0 1� � � � � , � � � �� � � �� �� ��� � ��� � "#$ %� 0 �� �� ��� � &�� � $'( %� 0 � � � 0 0 0 0 1 0 0 �$'( %� �"#$ %� 0 &� sin�%�� ��� cos �%�� 0�� �� � � , . � �� � ��/� �0 �/� �0 /� 0 0 0 0 0 � �� � � where, the state vector x t is [u w q θ h] in the longitudinal motion, the mas is m, a is the system transition matrix, the control matrix is b, the input vector ut is [de τ], and de is the elevator and τ is the throttle control input, u, w are the forward and vertical velocities, q, θ ,h are the pitch rate and pitch angles and the altitude. fig. 1. the platform of cessna 172 [24]. 3. control system design the airspeed and altitude controllers of the aircraft are significantly affected by the thrust force and the control surfaces. the thrust force generated by the throttle control and the control surfaces is adjusted by the longitudinal control angle (elevator). the controllability and observability of the system eq. (1) are studied based on the theory of controllability and observability as following. malik m. a. al-isawi al-khwarizmi engineering journal, vol. 16, no. 3, p.p. 4353 (2020) 45 let us define the controllability matrix as [26]. 1234 � [. �. �6. … �289. ] …(2) the matrix cntr has full rank, so the system is controllable. on the other hand, the observability matrix is ;<=� � � � � 1 1� 1�6 ⋮ 1�289� � � � …(3) the matrix obse has full rank, so the system is observable. 3.1 lqr controller lqr is an optimal control approach which is based on closed-loop control with the linear state feedback or output feedback [27]. the state feedback controller, lqr has shown in fig.2 fig. 2. block diagram of lqr controller. in lqr, a cost function for optimal control performance is: ? � @ �abca � dbed�fgh i …(4) the vector u in eq. (4) is important to know that it minimizes the quadratic cost function, which leads to optimal feedback control law represented in eq. 5. the cost function has a unique minimum that can be obtained by solving the algebraic riccati equation. the parameters q and r are employed as design parameters to judge the state variables and the control signals. choosing a large value of r led to stabilizing the system with less (weighted) energy, but this is an expensive control strategy. on the other hand, a small value for r means you don't want a good performance. this is similarly for q. so, there is a trade-off between the two assumptions [27]. u =-kx … (5) the steady-state optimal gain is determined by using the riccati equation as below �bj � j� � j.e89.bj �c � 0 …(6) where q is the state-cost matrix, and r is the performance index matrix. the selection weight matrices q and r are very important in the lqr method, which should be symmetric and nonnegative matrices. the weight matrices affect the control performance. these matrices are determined by the experience of engineers who are familiar with the controlled system [28]. 3.2 fuzzy logic controller (flc) fuzzy logic tools are a mathematical tool to handle's ambiguity and uncertainty existing in complex problems, and it was introduced in 1965 by lofti zadeh. it provides a technique to deal with the imprecision and details of the information. [29, 30]. it consists of three basic segments (fuzzification, fuzzy inference process, and defuzzification), as shown in fig. 3. in general, the fuzzypid control strategies can improve dynamic performance from the design point. it is based on the conventional pid controller as the foundation. the advantage of fuzzy logic to self-tune the pid parameters are used to derive adaptive fuzzy-pid. in the fuzzy pid, there are two inputs and three outputs. the inputs of the fuzzy pid are the error, e(t), and the error gradient, ∆e=de(t)/dt while the outputs are pid coefficients, kp, ki, and kd. then; fuzzy inference gives a nonlinear mapping from the inputs to the pid coefficients, as shown in the block diagram in fig. 3 [31, 32, and 33]. 4. state estimation for uav using aukf the aukf is built to estimate the longitudinal dynamic state for uav. the state vector and control vector are: x=[u w q θ]t, u=[de τ] …(7) then, the state space of the uav process and measurement models is: ak � �k,k89ak89 � .dk �mk …(8) nk � okak � pk …(9) where a is a transition dynamic matrix, b is control matrix, h is the measurement matrix, mk is a white gaussian for the process and pk is mean white gaussian for measurement. qrmkmsbt � ck , qrpkpsbt � ek , qrmkpsbt � 0 …(10) where qk is the process noise and rk is the measurement noise. the algorithm of ukf [9] is shown in table 1. + x model k u malik m. a. al-isawi al-khwarizmi engineering journal, vol. 16, no. 3, p.p. 4353 (2020) 46 table 1, ukf algorithm create sigma point � � [au au ∓ �w�( � x�jy�s ] ' � 1,2,……… . 2( create weight points �i �\� � ] 2^] �i �_� � �i �\� � �1 � `6 � a� �s �_� � �s �\� � 9 6�2^]� ' � 1,2,……2 x � `6�( � b� � ( 1e � 4 ≤ ` ≤ 1 b � 0 a � 2 transfer sigma points ��fk\k89�s � h����s� ' � 0,1,… . 2(. mean auk\k89 � ∑ �s\��fk\k89�s62sji covariance jk\k89 �k�s_[�fk\k89 62 sji � auk\k89] [�fk\k89 � auk\k89]b � c observation model ��lk\k89�s � ℎ���fk\k89�s� predicted observation n̂k\k89 � ∑ �s\��lk\k89�s62sji innovation covariance joo � ∑ �s_[�lk\k89 �62sji nk\k89] [�lk\k89 � n̂k\k89]b � e cross covariance jyp �k�s_[�fk\k89 62 sji � auk\k89] [�lk\k89 � n̂k\k89]b update qk � jypjoo89 auk � auk\k89 � qk�nk � n̂k\k89� jk � jk\k89 � qkjoo qkb the adaptive unscented kalman filter (aukf) algorithm can be shown in [9] and the summary is list in table 2. 5. simulation and results the proposed control schemes are implemented, and the corresponding results for a full cessna aircraft model are presented. the fuzzy sets of the input and output variables are defined as {negative big, negative middle, negative small, zero, positive big, positive middle, positive small}, or {nb， nm， ns， z， ps， pm， pb} as a simplification. the membership functions are the trapezoid, as shown in fig.4 and fig. 5. table 2, the adaptive unscented kalman filter (aukf) algorithm determine the residual measurement rk � nk � n̂k calculate the degree of divergence (dod) the first parameter of dod st( u u � 1 (krs 2 sj9 the second parameter of dod covariance v v � rkbrk ( determine the softening factor α the output membership of the fuzzy logic (the input memberships are mean and covariance) calculate the new model of weighted noise covariance matrices ek � e`86�k^9� ck � c`86�k^9� the weighted covariance is jwk\k89 � jk\k89`6k update jk\k89 � `6∑ �s_[�fk\k89 �62sji auk\k89] [�fk\k89 � auk\k89]b � c joo � `6k ∑ �s_[�lk\k89 � nk\k89]62sji [�lk\k89 � n̂k\k89]b � `86e jyp � `6kk�s_[�fk\k89 � auk\k89] 62 sji [�lk\k89 � n̂k\k89]b it is noticed that these functions are designed around the zero value to guarantee the control sensitivity at a small deviation. according to the different values of e and ∆e taken from the experiences; these summarized the behavior of system response for uav [33], it can be concluded as follows in table 3: malik m. a. al-isawi al-khwarizmi engineering journal, vol. 16, no. 3, p.p. 4353 (2020) 47 fig. 3. the blocks diagram of the fuzzy-pid controller. table 3, rule of kp, ki , and kd fig. 4. the membership function of the input variables. fig. 5. the membership function of the output variables. fig. 6. block diagram of the fuzzy-pid controller with lqr 5.1 step input to the fuzzy -pid with lqr controller in fig 6, fuzzy-pid with lqr controller was designed to make sure to stabilize the aircraft within a certain threshold. a unit step command is required to follow the reference value. in longitudinal control, the altitude and airspeed are controlled by using the combination of elevator and throttle, in fig.7 shown that the fuzzy-pid controller was given a step of 200 ft/s as a reference for the airspeed input. the controller should be able to track that reference airspeed while another fuzzypid controller was regulating the attitude, as shown in fig.8. kp, ki, kd ∆e nb nm ns z ps pm pb e nb pb,nb,ns pb,nb,nm pb,nm,nb pb,nm,nb pm,ns,nb ps,z,nb z,z,z nm pm,nb,ns pm,nm,ns ps,nm,nm ps,ns,nm ps,ns,nm z,z,ns z,z,z ns pm,nb,z ps,nm,ns z,ns,nm z,ns,nm z,z,ns ns,ps,ns nm,ps,z z pm,nm,z pm,nm,ns ps,ns,ns z,z,ns ns,ps,ns nm,ps,ns nm,pm,z ps pm,nm,z ps,ns,z z,z,z z,ps,z ns,ps,z ns,pm,z nm,pm,z pm ps,z,pm z,z,ps ns,ps,ps ns,ps,ps nm,pm,ps nm,pb,ps nb,pb,pb pb z.z,pb z,z,pm ns,ps,pm nm,pm,pm nm,pm,ps nb,pb,ps nb,pb,pb y model pid controller ∆e rule base inference f u zzificatio n d e fu z zific atio n e kp, ki, kd + u de/dt fuzzy controller + fuzzypid model outer-loop reference input lqr inner-loop malik m. a. al-isawi al-khwarizmi engineering journal, vol. 16, no. 3, p.p. 4353 (2020) 48 fig. 7. airspeed with step throttle input. fig. 8. altitude with step elevator input. 5.2 verification change step inputs in both throttle control and elevator input were studied separately, to make sure the controller works correctly. a) throttle control increased while the elevator fixed, fig. 9 shown that the airspeed was increased from 200 ft/s to 300 ft/s at 6s while the altitude was increasing slowly to 360 ft as we expected as shown fig.10. b) the throttle control is fixed while the elevator increased. fig.11 show that the airspeed was not affected, while the altitude increased with elevation, as shown in fig.12. fig. 9. airspeed increase by change the throttle control. fig. 10. altitude change when throttle change. fig. 11. airspeed fixed with elevator change. 0 2 4 6 8 10 12 14 16 18 20 -50 0 50 100 150 200 250 time (s) u ( ft /s ) 0 2 4 6 8 10 12 14 16 18 20 0 50 100 150 200 250 300 time (s) a lt it u d e ( ft ) 0 2 4 6 8 10 12 14 16 18 20 -50 0 50 100 150 200 250 300 350 time (s) u ( ft /s ) 0 2 4 6 8 10 12 14 16 18 20 0 50 100 150 200 250 300 350 400 time (s) a lt it u d e ( ft ) 0 2 4 6 8 10 12 14 16 18 20 -50 0 50 100 150 200 250 time (s) u ( ft /s ) malik m. a. al-isawi al-khwarizmi engineering journal, vol. 16, no. 3, p.p. 4353 (2020) 49 fig. 12. altitude change when elevator change. 5.3 the comparing between the controllers the performance control and the output response of two controller schemes with respect to the airspeed are shown in fig.13. also, the airspeed and altitude of the step input signal are shown in fig.13, 14 and 15. it noticed that the proposed fuzzy-pid with the lqr controller has the best performance and has achieved a better response than the fuzzy pid controller. compared to the proposal controller with fuzzy pid, the settling, peak time, rising time, and overshoot have been improved, as shown in figs. 14, 15. therefore, the performance of the uav can be enhanced by employing the fuzzy-pid with lqr controller. fig. 13. airspeed due to both controllers fig. 14. the airspeed performance control for both. fig. 15. the altitude performance control for both. 5.4 the disturbance effects to investigate the fuzzy -pid with the lqr controller performance of the system, the disturbance effects are applied to the pitch angle as shown in fig 16. it is seen that the controller's response is to work properly when we considered the disturbance effects. fig. 16. the disturbance effects on the pitch. 0 2 4 6 8 10 12 14 16 18 20 0 50 100 150 200 250 300 time (s) a lt it u d e ( ft ) 0 2 4 6 8 10 12 14 16 18 20 -0.2 0 0.2 0.4 0.6 0.8 1 1.2 time (s) u f t/ s fuzzy-pid+lqr fuzzy-pid 0 1.5 3 4.5 6 7.5 9 rise time (s) peak time (s) max overshoot setlling time (s) 1.39 2.9 7.7 4.4 1.28 2.6 5.9 3.9 the performance control of airspeed fuzzy-pid fuzzy-pid+lqr 0 10 20 30 rise time (s) peak time (s) max overshoot setlling time (s) 1.68 2.71 24.79 5.25 1.57 2.5 15.9 4.8 the performance control of altitude fuzzy-pid fuzzy-pid+lqr malik m. a. al-isawi al-khwarizmi engineering journal, vol. 16, no. 3, p.p. 4353 (2020) 50 5.5. the noise effects the noises are considered for roll angle controller in the system and the noises parameters are taken as qk=0.4, rk =0.6. since the noise effects on the roll angle, the controller may cause inaccurate functioning of the roll angle controller. so, the response of the performance of the controller with and without aukf under noises is verified and shown in fig. (17). it is noticed that the roll angle controller with aukf reduces the noise effects when compared to the controller without noise under the same conditions. moreover, it shows more reliable performance than the roll angle controller without aukf. the difference of the roll angle between the controller based on aukf with noise and with noise is shown in fig. (18). it is noticed the error in the controller of the roll angle based on aukf is between -0.05 to 0.05 while the error in the controller of the roll angle with noise is between 0.1 to 0.1. fig. 17. estimation the pitch angle using controller based on aukf fig. 18. the pitch angle error in both controller with and without using aukf. 6. conclusion a nonlinear control algorithm was designed and experiment for the cessna 172 aircraft in longitudinal motion using dual fuzzy-pid and lqr controller. the performance of this controller is compared with the fuzzy-pid controller. the longitudinal controller is described as the following; the elevator is the first input that responsible for stabilized the altitude, while the throttle (second input) is employed to stabilize the airspeed of the uav. it is noticed that the airspeed still stabilization when the throttle control increase, as shown in fig. 9. while small steady-state error occurs for altitude stabilization, as shown in fig. 10. the reason for this error is the approximation used for finding the altitude. this error, however, is rather small and can be neglected. another interesting observation is also the steady-state error for altitude shown in fig. 12 when the elevator increases for the same reason. regarding the performance control in fig. 14 and fig.15, it should be mentioned that the performance for the second controller (i.e. fuzzypid with lqr) is better than the first controller, the reason is we employ lqr as the inner loop to achieve the stability of the system before the out loop controller works and the states could be easily held with reference values. in the results, the fuzzy-pid with lqr shows a good response to track the reference value of the roll angle when a sudden change occurs. the adaptive unscented kalman filtering (aukf) is used in the controller to estimate the roll angle. the result shows that the proposed method is decreased the influence of noise. the future work is to design an autopilot system that will be able to control and navigate both longitudinal and lateral motion. this system design is a sensor fusion of multi-sensor using our algorithm called an adaptive unscented kalman filter (aukf) [9]. 7. references [1] m.m. al-isawi and j.z. sasiadek, “guidance and control of autonomous, flexible wing uav with advanced vision system,” iee/ 23rd international conference on methods & models in automation & robotics (mmar), pp. 441-448, 2018. 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[33] y. shengyi, l. kunqin, and s. jiao, “design and simulation of the longitudinal autopilot of uav based on self-adaptive fuzzy pid control,” international conference on computational intelligence and security, 2009. ���� 3ال��د، �16��� ال��ارز�� ال������ ال���� ��ل ���� ��� ،2020( 4353( 53 ال�/دوج وو-�ة ال+�*( lqr ال+�*( )� ال'�&%ات #�ون ط��ر ��� أ��س fuzzy-pid ***�4ل��س أو **�'�� 34�ر��2�ن * ال��1�وي��� ��ل ���� �ارز��/ ����� ���اد� *،**0/. ھ!� � ا�,#'�+*و)'&/ %$#� ا�"!� � ا� %!�ا -����� %�ر�8�ن /0/. ھ!� � ا�,#'�)#6 وا��45ء *** @kecbu.uobaghdad.edu.iqmalik *ا�>*;� ا:�'8*و)�: @kecbu.uobaghdad.edu.iqadnan**ا�>*;� ا:�'8*و)�: osemudiamenadoghe@cmail.carleton.ca***ا�>*;� ا:�'8*و)�: �� ال�5 �;� ��ون ط#�ر �/�b;�$b8م ھ@ا ا�>?< +=,#. � �<%*,� ���ا80*ح ھ@ا ا�>?< ا��g .'?8 ا�?$�b ا�,fدو�� (ا�?$�b ا��ا(uav). �#$d �"�ز +?'. ط ��#�*+ �id .j!� kl رة�<l �#$dا��*ا��� ا��8@;� ا�ا �b$n �g .'?8�ة ا�n@%#�. و�ارز�#� ا��8�g#* ا b8*ار 0�ي (+'�5#). (lqr) وا���ر�#�) �!�ًء p$l ا�� �g �#ارز��d p$l �#ر���8�w<8+ *#g إ�uرة �*��#�. و�nة ا�fuzzy-pid .'?8 ا�,t��b ، +�8,� و�nة ا��g .'?8 ا�?$�b ا��) �b8x,�8'��$#� وا�8!� >#� وا�(ا �[w (ا:ر+�5ع) وا�/*�l (ا�/*�l ا�]�;�) �$z�i*ة. ;8. ا 8��ام �*yu %��,�ن � �g .'?8�ھ� ا �n*8b,�دو�� اf,�) اaukf( 88� .8;,*��#� و�رة ا�u^ا w< .). +. ا�k� db?8 ا b8*ار و��8)� ا�!�jم �g +]*�� �?�%�ة١٧٢+t#$b ا�4�[�ء. +. +�b;. ا�!,�ذج ا�*;�[� �$z�i*ة ( #/!� this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 19, no. 2, june, (2023) p. p. 1525 determination of the optimum conditions for removal of congo red dye by peroxidase enzyme plant aula. i. ridha* mohanad j. m-ridha** *,** department of environmental engineering/ collage of engineering/ university of baghdad/ baghdad/ iraq *email: ola.reda2011m@coeng.uobaghdad.edu.iq **email: muhannadenviro@coeng.uobaghdad.edu.iq (received 18 january 2023; accepted 6 march 2023) https://doi.org/10.22153/kej.2023.03.001 abstract the pollution producing from textile industries effluents is growing since the years, due to at discharged lots of it in water without treatment. the resulting effluent is colourful, highly toxic, and poses a significant environmental hazard. this problem can be solved by using enzymic biological treatment, where the congo red dye was used with concentrations (100,200,300,500) mg /l, ph values (3,4,5,6,7,8), and variable temperatures (25,35,45)°c, the best removal of congo red (cr) dye under optimum conditions for degradation was at concentration of 100 mg/l, at (ph 6, 25 °c) with efficiency of 99.85 % using the peroxidase enzyme extracted from red radish plant, while the removal percentage decreased when increase dye concentration . keywords: peroxidase enzyme, congo red dye, plant enzyme, decolorization. 1. introduction water is one of the essential elements for life on earth, along with air and soil. it is regarded as one of the important elements for both human and industrial development. industrial effluents like wastewater from the textile industry significantly damage water bodies by increasing demand for biochemical and chemical oxygen (bod and cod), decreasing photosynthesis and plant growth, and interfering with the food chain of living things [1]. there are different ways to remove dyes from wastewater as (physical, chemical, or biological) methods [2], as adsorption [3], electro-oxidation [4], fenton reaction [5], biodegradation [6], coagulation and precipitation [7], electrocoagulation [8]. also, degradation by use bacteria, fungi, and plants to remove the color textile dyes [1]. where employ the enzymes extracted from it is, to dissolved this problem. using dye in the textile industry creates substances with high toxic levels and resilience to natural decomposition that are extremely harmful to humans and the environment. one technique used to regard textile dyes is biodegradation, an innovative approach to conventional chemical and physical treatments [9]. changing, transforming, or mineralizing textile dye within certain limitations is possible using plant enzymes to be considered the most effective and stable technique [1]. the percentage of the lost dyes at discharge maybe reach 50 percent; when dyes are discharged without treatment [10]. it affects the environment for extended times, which causes unhealthy conditions for the photosynthetic of aquatic plants and affects all living bodies, which can be caused to carcinogenic [10]. among these dyes are a group of azo dyes of different densities. it has high-water solubility, so they are easily transmitted to the organism through the food chain, causing kidney damage, muscle and nervous spasms, and high body temperature [11]. moreover, the dyes are hurtful lead to genetic mutations or carcinogenic and teratogenic cells mailto:ola.reda2011m@coeng.uobaghdad.edu.iq https://doi.org/10.22153/kej.2023.03.001 aula. i. ridha al-khwarizmi engineering journal, vol. 19, no. 2, p.p. 1525 (2023) 16 [12; 13], and they cause carcinogenic to the liver and spleen, dye distortions in human cells and dna abnormalities in some animals [14], as well as block the penetration of sunlight into the aquatic environment and prevent the growth of life in it [15]. biodegradation is the process of mineralizing or transforming the contaminant by the enzymes derived from plants, bacteria, and fungi [1]. the enzyme does as catalyze oxidation for electron from substrate is (bh₂), and produce oxidized organic material (b₂), [16]: bh₂ + h₂o₂ 𝑝𝑒𝑟𝑜𝑥𝑖𝑑𝑎𝑠𝑒 → b₂ + 2(h₂o) where this research aims to remove azo dyes by biodegradation using peroxidase enzyme extracted from plant origin, such as the removal of congo red (cr) dye with a concentration of 100 mg/l , where it was decomposed with an efficiency of 99.85 % using the peroxidase enzyme extracted from red radish plant immobilized by sodium alginate after passing 24 hr., under optimum conditions for degradation for this dye where ph 6, temperature 25 °c , with enzyme ratio adding to dye was 2.5:3 (w:v) [17]. 2. methodology the experimental work used in this study for determination optimum conditions for congo red (cr) decolorization the peroxidase enzyme was extraction from red radish and immobilization it’s, then batch experiments procedure for determination (initial dye concentration, ph, temperature) for decolorization of congo red, finally was use design of experiments program (doe). 2.1. material and apparatuses materials and dye employed in this study are shown in table (1) and table (2). table 1, materials used material company, origin sodium acetate (c₂h₃nao₂) purity (99%) bdh, england sodium hydroxide (naoh) purity (98%) fluka, switzerland hydrochloric acid (hcl) purity (37%) fluka, switzerland tris-hydroxymethyl amino methane (tris-hcl) purity (99.9%) fluka, switzerland congo red (cr) (c32h22n6na2o6s2) purity (99%) fluka, switzerland na-alginate (nac6h7o6) purity (99%) merck, germany calcium chloride (cacl2) purity (≥97.0%) merck, germany table 2, dye properties property congo red dye symbol cr structure formula c₃₂h₂₂n₆na₂o₆s₂ exterior molecular weight 696.7(g/mole) solubility in water 10 mg/ml 20°c aula. i. ridha al-khwarizmi engineering journal, vol. 19, no. 2, p.p. 1525 (2023) 17 also, the following apparatuses was used in this study: (shaker incubator, lsi-3016a, korea), (uvvis spectrophotometer, -apel pd-303 uv spectrophotometer japan) (balance, beakers, cylinders, flask, pipet, filtering paper). 2.2. extraction of peroxidase enzyme and immobilization it’s by using blender, fifty grams from red radish plant were homogenized in 30 ml of sodium acetate (ph 6, 0.1 m) for 5 minutes, the peroxidase enzyme extract by centrifuged filtered at a speed of 10000 rpm for ten minutes at 4°c, ratio of enzyme to buffer 2:1 (w: v) as extracted ratio, then the peroxidase activity and protein content were calculated at 470 nm [18]. by using heating, 5grams of 0.1m na-alginate ph 6 was dissolved with 100 ml distilled water and cool it, then, added the extract peroxidase enzyme to na-alginate gel was percentage 0.25 :1 (v: v) for immobilized the enzyme. cacl₂ was preparation by dissolved 0.2 m cacl₂ solution by dissolved 2.2 g cacl₂ powder in 100 ml from distilled water. in order to prepare the enzyme beads was use syringe needle, was instillation the immobilized peroxidase gel by na alginate in a cacl₂ solution. then used in degradation of congo red dye [19; 20]. 2.3. determination the optimum conditions for decolorization congo red dye (cr) was prepared in 100, 200, 300 and 500 mg/l by dissolved in distilled water and adjust the dye solution at ph 6. after determining the optimum concentration of the dye, the optimum ph was determined for decolorization, 100 mg/l congo red dye (cr) was prepared with distilled water at ph values (3,4,5,6,7, and 8). after determining the concentration and ph of the dye, the optimum temperature was determined, 100 mg/l congo red dye (cr) was dissolved in distilled water and adjusted the solution at ph 6. in each of the above three experiments to determine (dye concentration, ph, and temperature), where added the immobilized peroxidase beads to dye solution by ratio 2.5:3 (w : v), the solution were agitated at 25°c at 120 rpm using shaker incubator a thermostatic,lsi-3016a, korea , then screened after 24 hr. at 540 nm with a uv-vis spectrophotometer (apel pd-303 uv spectrophotometer japan) , the decolorization efficiency for dye by immobilized peroxidase was assessed by observing the decrease in absorbance [18;21]. 2.4. design of experimental method (doe) in order to estimate optimum conditions for (ph, initial dye concentration(mg/l), amount of enzyme added to dye solution (g/ml) that they give best decolorization of congo red dye, were using the batch system by applied the many values for these conditions, at 25 ºc, and 540 nm., then analyze it statistically. design of experimental was used in 20 runs with factorial method, a different value of initial concentration has been encoded as(a), ph value as (b), ratio of enzyme adding dye as (c), and removal efficiency percent as input data to the program. 3. results and discussion 3.1. effect of initial concentration for dye and operating time figure (1) shows the best removal of congo red was at a concentration of 100 mg/l, where it reached 99.85% after 24 hours, which is the ideal contact time for the degradation dye, using immobilize peroxidase enzyme. while the removal efficiency for each (200,300,500) mg /l were (99.16, 98.37, and 97.08) % respectively, after same time. it is clear from this that as dye concentration increases the percentage of dye removal decreases because a result of occupying the sorption sites in beads by the dye molecules during the operation, and the removal efficiency is low at high dye concentration [24]. also, the contact period important in the decolorization process. where the efficacy of dye removal rises the longer the contact period [22]. aula. i. ridha al-khwarizmi engineering journal, vol. 19, no. 2, p.p. 1525 (2023) 18 fig. 1. effect of initial concentration for dye and operating time 3.2. ph effect on decolorization figure (2) shows maximum value for decolorization for the congo red (cr) was 99.8% at ph 6, after 24 hr., while the removal efficiency at use ph values (3, 4, 5, 7, and 8) were (87.6, 87.97, 89.05, 96.09, and 91.87) % respectively, after same time. many of time, ph level is an important variable affecting sorption for dye, because it affects the absorbent's surface charge, surface binding sites, and degree of ionization [23]. fig. 2. ph effect on decolorization. 3.3. effect of temperature on decolorization figure (3) shows after the experiment was conducted at temperatures (25, 35, and 45) °c, respectively, was the optimum temperature for decolorization of 100 mg/l congo red (cr) dye is 25 °c, where the removal efficiency was 99.8 % after 24 hr., and (82.6, 80.7) % for (35,45) °c. figure (4.a; b) shows the results before and after removed congo red dye. where the higher of temperature, the enzyme will lose its enzymatic activity causing a fall in removal efficiency due to the kinetic of the molecules raise leading to increase interaction in enzyme active sites, until enzyme maximum activity at optimum temperature, with increment in temperature, the enzyme activity will decreasing because denaturation enzyme molecule and disturbance in the 3 -dimensional conformation for enzyme , leading to happening changes in enzyme active sites [24]. 0 20 40 60 80 100 20 21 22 23 24r e m o v a l e ff ic ie n c y % time (hr.) initial dye concentrations 100 mg/l 200mg/l 300mg/l 500mg/l 0 10 20 30 40 50 60 70 80 90 100 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 r e m o v a l e ff ic ie n c y % time (hr.) ph values 3 4 5 6 7 8 aula. i. ridha al-khwarizmi engineering journal, vol. 19, no. 2, p.p. 1525 (2023) 19 fig. 3. effect of temperature on decolorization at (25, 35,45) °c fig. 4. (a; b). the results before and after removed congo red dye. 3.4. design of experimental method (doe) design of experimental is a piece of software designed to help with the design and interpretation of multi-factor experiments. in polymer processing, using the software to help for design an experiment to see how a property, such as tensile strength varies with changes in the processing conditions [25]. the results show below for design experiment program to get the best removal efficiency for congo red dye by batch experiment system at different conditions for three factors initial concentration dye(mg/l), ph, and (enzyme to dye) ratio (g/ml) as shows in table (3). 0 10 20 30 40 50 60 70 80 90 100 0 1 19 20 21 22 23 24 r e m o v a l e ff ic ie n c y % time (hr.) 25°c 35°c 45°c aula. i. ridha al-khwarizmi engineering journal, vol. 19, no. 2, p.p. 1525 (2023) 20 table 3, design experiment program to get the best removal efficiency for congo red dye by batch experiment system 3.5. analysis of variance (anova) statistical significance of the factors was established by analysis of variance (anova) results showed the quadratic model in table (4), this table it is showed the ability of applied this model with a highly significant model p-value, which was less than 0.05 and high f-value of 50.77. the experimental values obtained from the lab experiments were compared with the predicted results calculated by statistical design software. the value of coefficient r² is equal to 0.9068, the predicted r² of 0.9068 is in reasonable agreement with the adjusted r² of 0.9545; i.e., the difference is less than 0.2, that indicated that the experimental data fits with the quadratic model. while, [26] found in (anova) analysis that the factors significant on degradation of congo red to get on (r²=0.9900) at the use (27.21 mg/l congo red concentration, 2.07 unit for peroxidase enzyme activity, 0.15 mmol/l h₂o₂) give the maximum degradation of 58.13%. in general, the peroxidase enzyme of vegetable origin is effective in removing azo dyes and gives satisfactory results, where [27] found that effects of factors (ph, enzyme dose, and dye concentration) on degradation of violet azo dye by peroxidase enzyme from plant origin after done 20 experiments with different combinations, where observed that the decolorization reach 87.95 %, with the fit of quadratic model that was obvious by high r² value of 0.9903. the f-values in table (4) shows that the initial concentration is the most effective factor in color removal, followed by the ph factor, and then the enzyme added to the dye solution is less than the other two factors. run factor 1 a:c0 (mg/l) factor 2 b: ph factor3 c:(enzyme: dye) ratio (g/ml) response1 removal efficiency (r)(%) 1 282.4 6.9 2.0 99.4 2 550.0 5.5 1.4 96.9 3 817.6 4.0 2.0 98.5 4 550.0 8.0 1.4 98.9 5 100.0 5.5 1.4 94.1 6 550.0 5.5 1.4 99.3 7 817.6 6.9 0.7 99.5 8 282.4 4.0 0.7 98.4 9 282.4 4.0 2.0 98.9 10 550.0 5.5 1.4 99.5 11 282.4 6.9 0.7 99.1 12 550.0 5.5 0.3 99.2 13 550.0 5.5 1.4 99.4 14 817.6 7.0 2.0 99.8 15 550.0 5.5 1.4 99.6 16 550.0 5.5 2.5 99.7 17 1000.0 5.5 1.4 99.8 18 817.6 4.0 0.7 99.5 19 550.0 3.0 1.4 99.1 20 550.0 5.5 1.4 99.4 aula. i. ridha al-khwarizmi engineering journal, vol. 19, no. 2, p.p. 1525 (2023) 21 table 4, removal efficiency of congo red dye is the target in this table. the following equation was used in this work to evaluate the terms of actual factors for removal efficiency by the design experiment program. removal efficiency (r)(%) = 90.42791 − 1.59003b − 2.68865 c + 0.013541 a + 0.201133 b ∗ c + 0.000251 b ∗ a − 0.001955 c ∗ b + 0.103457 b² + 0.984972 c ² where: a: initial concentration for dye (mg/l). b: ph c: enzyme: dye (g/ml), where the ratio of dye is stable at 3 while the enzyme ratio is change such as in table (3). where figures (5. a; b; c) shows the results for these experiments. (a) source sum of squares df mean square f-value p-value model 151.15 8 18.89 50.77 < 0.0001 significant a-ph 0.0417 1 0.0417 0.1120 0.7442 b-enzyme 0.0157 1 0.0157 0.0423 0.8408 c-c0 146.36 1 146.36 393.32 < 0.0001 ab 0.3200 1 0.3200 0.8599 0.3737 ac 0.0800 1 0.0800 0.2150 0.6519 bc 0.9800 1 0.9800 2.63 0.1329 a² 0.7607 1 0.7607 2.04 0.1806 b² 2.83 1 2.83 7.60 0.0187 residual 4.09 11 0.3721 lack of fit 1.74 6 0.2897 0.6151 0.7157 not significant pure error 2.35 5 0.4710 cor total 155.25 19 aula. i. ridha al-khwarizmi engineering journal, vol. 19, no. 2, p.p. 1525 (2023) 22 ( b) ( c ) fig. 5. (a; b; c) effect of factors on removal efficiency of congo red dye. where shows the results for these experiments and the influence of each (initial concentration, ph, and enzyme ratio adding to dye) on removal efficiency, the findings indicate that initial dye concentration of 817.6 mg/l, ph from (4 to 7), and enzyme adding ratio to dye was (0.7 to 2) to achieve a removal efficiency of reach 95 percent of the congo red dye. 4. conclusion this study concluded that peroxidase enzyme extracted from red radish plant is a good source for azo dye decolorization such as congo red dye, at the optimal conditions for decolorization dye ph 6.0, temperature 25 ᵒc, after 24 hr., at 540 nm, when enzyme adding to dye by ratio (2.5:3) (w: v). peroxidase immobilized enzyme by sodium alginate can give a good result when using to remove the congo red azo dye from wastewater resulting from many industries as textile industry which cause healthy and environmental serious problems as cancer and genetic distortions. aula. i. ridha al-khwarizmi engineering journal, vol. 19, no. 2, p.p. 1525 (2023) 23 notation cr congo red dye bh₂ substrate b₂ oxidized organic material dna deoxyribonucleic acid h₂o water hr. time ph acidic degree °c temperature w weight v volume uv-vis ultraviolet–visible cacl₂ calcium chloride doe design of experimental anova analysis of variance 5. references [1] b. lellis, c.z. fávaro -polonio j. a. pamphile, j. c. polonio, “effects of textile dyes on health and the environment and bioremediation potential of living organisms,” biotechnology research and innovation, vol. 3, no.2, pp. 275-290, july– december 2019, https://doi.org/10.1016/j.biori.2019.09.001 [2] p. k. yeow, s. w. wong, and t. hadibarata, ‟removal of azo and anthraquinone dye by plant,” biomass as adsorbent a review, vol. 11, no. 1, pp. 8218 8232, 2020, https://doi.org/10.33263/briac111.821882 32. 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[27] n. shazia, n. b haq, “mechanistic study of degradation of basic violet 3 by citrus limon peroxidase and phytotoxicity assessment of its degradation products,” biochemical engineering journal, 2014, http://dx.doi.org/10.1016/j.bej.2014.11.02 https://www.researchgate.net/publication/366988554_investigation_activity_and_stability_of_peroxidase_plant_enzyme_to_decolorize_azo_dyes https://www.researchgate.net/publication/366988554_investigation_activity_and_stability_of_peroxidase_plant_enzyme_to_decolorize_azo_dyes https://www.researchgate.net/publication/366988554_investigation_activity_and_stability_of_peroxidase_plant_enzyme_to_decolorize_azo_dyes https://www.researchgate.net/publication/366988554_investigation_activity_and_stability_of_peroxidase_plant_enzyme_to_decolorize_azo_dyes https://doi.org/10.1038/natrevmats.2016.33 http://dx.doi.org/10.1016/j.bej.2014.11.02 (2023) 15-25، صفحة 2، العدد19مجلة الخوارزمي الهندسية المجلد عال إسماعيل رضا 25 البيروكسيديز النباتي بواسطة انزيمتحديد الشروط المثلى إلزالة صبغة الكونغو الحمراء **مهند جاسم محمد رضا *إسماعيل رضاعال العراق /بغداد /بغدادجامعة /الهندسةكلية /البيئيةقسم الهندسة *،** ola.reda2011m@coeng.uobaghdad.edu.iq:البريد االلكتروني* muhannadenviro@coeng.uobaghdad.edu.iq **البريد االلكتروني: الخالصة بسبب تصريف الكثير منها في المياه المفتوحة دون معالجة. المخلفات الناتجة سنوات،يتزايد التلوث الناتج عن المخلفات السائلة للصناعات النسيجية منذ حيث تم استخدام صبغة الكونغو الحمراء األنزيمية،يمكن حل هذه المشكلة باستخدام المعالجة البيولوجية كبيرا . بيئيا خطرا تكون ملونة وشديدة السمية وتشكل كانت أفضل إزالة مئوية،( درجة 45 35،25( ودرجات حرارة متغيرة )8،7،6،5،4،3( مجم / لتر وقيم األس الهيدروجيني )500،300،200،100) اكيزبتر ٪ 99.85 درجة مئوية بكفاءة 25 و (ph 6)الهيدروجيني عند االس لتر،مجم / 100( في الظروف المثلى للتحلل بتركيز crلصبغة الكونغو الحمراء ) نسبة اإلزالة عند زيادة تركيز الصبغة. تنخفض من الفجل األحمر ، بينما لص استخدام إنزيم البيروكسيداز المستخواسطة ب mailto:ola.reda2011m@coeng.uobaghdad.edu.iq this is an open access article under the cc by license : al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 21, no. 2, june, (2025), pp. 106-116 impact of the number of reflecting elements and positioning of the reconfigurable star-passive-oris in mimo fso systems batool rafid natiq1*, lwaa faisal abdulameer2 and mohammad bagher dowlatshahi3 1,2department of information and communication engineering, al-khwarizmi college of engineering, university of baghdad, baghdad, iraq 3department of computer engineering, faculty of engineering, lorestan university, khoramabad, iran *corresponding author’s email: batoul.abd2203@kecbu.uobaghdad.edu.iq (received 11 december 2024; revised 9 january 2025; accepted 27 february 2025; published 1 march 2025) https://doi.org/10.22153/kej.2025.02.004 abstract this study aims to improve the performance of reconfigurable star-passive-oirs in multiple input multiple outputbased free-space optical (fso) communication systems. the study focuses on analysing the influence of two main factors: the number of reflective elements and the location of the smart surface. star-ris technology has shown great potential in improving spectrum efficiency and signal-to-noise and interference ratio (sinr) and in increasing channel gain by providing 360° coverage and reducing interference in environments with line-of-sight constraints. results reveal that increasing the number of reflective elements enhances signal strength and improves sinr, whilst placing the smart surface closer to the source or receiver achieves optimal performance. the study highlights star-ris technology’s ability to overcome traditional fso systems’ limitations and improve network performance in modern wireless communication environments. keywords: free space optics (fso); intelligent reflecting surface (irs); nonorthogonal multiple access (noma); radio frequency (rf); and simultaneous transmitting and reflecting reconfigurable intelligent surface (star-ris). 1. introduction in recent years, the high speed and simplicity of wireless communication environments have become essential [1]. free space optical (fso) communications are considered a potential alternative to offer quick data transfer rates [2]. fso is a promising candidate to meet the requirements of 5g and beyond (b5g), such as high capacity, high bandwidth, fast speed and low power consumption [3]. however, the trees and walls are regarded as obstacles and limitations; therefore, fso technology has certain fundamental drawbacks, such as little to no support and limited mobility for nonline of sight (nlos) [4]. in addition, the quality of fso is affected by several factors, such as atmospheric turbulence (at) (e.g. fog and rain) [5], [6]. fso’s performance might be enhanced by many methods such as the hybrid models of dual-hop rf-fso integrating the advantages of fso and rf communication [7]. research in this direction has many types which use hybrid rf-fso technologies together [7], [8], [9], [10]. although using fso/rf together has the advantage of helping overcome the disadvantages of fso, this solution increases the complexity and cost of the system [10]. the decode and forward (df) relay strategy can improve quality to enhance performance and mitigate disturbances [11], but it has drawbacks such as latency and high power consumption [11]. an intelligent reflecting surface (irs), which is a surface with many reflecting elements, can be used to reflect signals in the desired direction. furthermore, it can overcome fso’s nlos limitations, increase signal coverage, enhance channel conditions and create a virtual line of sight https://doi.org/10.22153/kej.2025.02.004 batool rafid natiq al-khwarizmi engineering journal, vol. 21, no.2, pp. 106-116 (2025) 107 los [5], [4]. hybrid fso/rf communication systems that use a reconfigurable intelligent surface (ris) can further improve fso performance [12]. optical intelligent reflecting surfaces (oirs) have the potential to improve the capabilities of future generations of optical wireless communication systems by reconfiguring the propagation environment of optical waves [13]. irs and oirs can be passive or active and reconfigurable or nonreconfigurable [14][15][16][17]. riss capable of simultaneous transmission and reflection, known as star-ris, are increasingly prevalent. starris can reflect and refract signals, providing complete wireless coverage and enhanced degrees of freedom (dofs) and providing transmitters for users on both sides. this type is different from the traditional irs, which only reflects signals to users on the same side, thus solving the limitation of traditional irs, which cannot be used when the transmitter and receiver are on different sides [18]. in addition, the number of reflecting elements and irs improve performance and increase gain, and this number depends on the type of application and the requirement of the design of the communication system [12]. furthermore, integrating multiple access methods with the irs is essential to address communication requirements efficiently for a wide range of services. these methods play a role in optimising the allocation of frequencies, ensuring speedy communication and promoting the development and expandability of the communication systems. one of these methods is orthogonal multiple access (oma), which is employed by the irs and offers advantages such as reducing interference [19]. oma includes techniques such as frequency division multiple access, orthogonal frequency division multiple access, code division multiple access and time division multiple access, which are effective in reducing interference to users, thereby improving reliability [19]. however, oma encounters impediments as an effect of altered channel conditions and data patterns, which can lead to the underutilisation of spectrum resources and a reduction in capacity [19]. on the one hand, nonorthogonal multiple access (noma) techniques offer an idea of shared resource utilisation, which substantially enhances efficiency through intelligent power allocation [20]. it effectively deals with signal weakening by strategic power allocation and using advanced coding methods that allow multiple data transmissions simultaneously [21][22]. by judicious use of resources, noma improves the resilience and efficiency of irs. successive interference cancellation (sic) plays a role in this context. sic helps untangle overlapping signals, which is important when multiple users are involved in noma scenarios [21]. multiple-input multiple-output (mimo) strategies have been extensively studied to enhance data rates and reliability without putting strain on time and spectrum resources [23]. this system consistently outperforms the single-input singleoutput system [23]. in the modern world of fso, reconfigurable star-passive-oirs is a potential technology that can enhance the efficacy of spectrum and network coverage. by manipulating the environment surrounding the radio waves, reconfigurable starpassive-oirs technology offers the ability to enhance the overall system performance whilst reducing interference and increasing the sinr. in addition, strategically locating reconfigurable star-passive-oirs plays a crucial role in increasing efficiency, especially in systems with los limitations. in this study, we investigate the effect of optimising irs location and the number of reflective elements on the performance improvement of a star-ris-based fso communication system. the paper is organised as follows: section 1 contains the introduction. section 2 details the associated work. section 3 presents the mathematical model, whilst section 4 provides numerical results and discussions. section 5 presents the study’s conclusion. 2. related work a future technique for future 5g and b5g wireless communications to improve coverage and capacity is ris, which has a low hardware cost and energy consumption [24]. in [25], the authors examined the potential of irss to alleviate the los constraint of fso systems. in [12], the authors suggested a novel wireless transmission method that employs ris for hybrid rf/fso communications. in [26], the researchers investigated the mathematical model and design of irs-assisted optic communication systems, which are employed to reduce the los demand for multilink fso systems. in [27], the impact of defects in sic technology when using irs with noma systems was discussed. in [28], the researchers improved the use of reconfigurable ris in radio frequency systems. the focus was on choosing the optimal number of adjustable reflective elements within the ris to achieve improved data transfer rates and energy efficiency. in [29], the authors discussed how to optimise the batool rafid natiq al-khwarizmi engineering journal, vol. 21, no.2, pp. 106-116 (2025) 108 location of the irs to achieve optimal performance in wireless communication systems. the paper presented an analytical study to determine the optimal location of irs by analysing the effect of different settings, such as surface height and stability, phase signal distribution and the effect of antenna orientation. a new star system design, which is based on reconfigurable intelligent surfaces (star-riss), was proposed [30]. the conventional ris was contrasted and investigated in comparison with star-riss [31]. irs and star-ris were systematically reviewed in [32] and [33], with a detailed explanation of them, clarifying their benefits and their general impact on the performance of networks for 5g, b5g and 6g. furthermore, their uses and challenges were presented with possible future research directions. in [34], a mathematical model was proposed to describe the mechanism of simultaneous transmission and reflection in star-ris, and new resource allocation schemes were designed to improve the efficiency of transmission and reflection, including power distribution between the two directions and development of algorithms to improve performance, such as optimising beamforming and maximising data transfer rate. in [35], the integration of active star-ris with massive mimo communication systems was proposed. in [36], star-ris was proposed to enhance covert communications in noma networks. the researchers focused on designing a system that ensures the existence of the communication is hidden from eavesdroppers whilst improving the efficiency of data transmission. the table below shows some previous works using ris or star-ris with different technologies and channels and their most important contributions. table 1, comprehensive review of ris and star-ris with many techniques in rf and fso communication systems ref. type of irs techniques channel type contribution [25] irs no fso focused on improving signal quality and increasing communication distance [12] irs no rf/fso improved the performance of hybrid communication systems that combine rf and fso systems [26] irs mimo fso developed mathematical models to analyse the performance of systems and proposed strategies to improve communication efficiency [28] irs no rf determined the optimal number of reflective elements in ris to achieve remarkable improvements in the performance of wireless communication systems [27] irs noma rf analysed the system’s performance under nonideal sic conditions and proposed improvements to increase communication efficiency [29] irs no rf proposed algorithms to determine the optimal location of ris with the aim of enhancing signal quality and extending coverage [34] star-ris no rf developed algorithms to optimise active beamforming in the base station and passive beamforming in star-ris, with the aim of improving system performance and reducing power consumption [35] star-ris mimo rf developed algorithms for power distribution and beamforming optimisation [36] star-ris noma rf analysed the probability of eavesdroppers discovering the communication and developing strategies for packet design and resource allocation to ensure confidentiality of communication this study aims to address the research gaps related to determining the optimal location and number of elements for star-passive reconfigurable optical systems (star-passiveoirs) in the mimo-fso environment. although previous research has provided mathematical models for the simultaneous transmission and reflection mechanism in star-ris and designed algorithms to optimise beamforming and resource allocation, the detailed impact of star-ris batool rafid natiq al-khwarizmi engineering journal, vol. 21, no.2, pp. 106-116 (2025) 109 location and number of reflective elements on system performance has not been sufficiently studied. this study presents an integrated theoretical and experimental analysis to determine the optimal number of reflective elements and the ideal location of star-ris in mimo-enabled fso systems by developing accurate mathematical models and analysing the system performance under effects such as dispersion, environmental disturbances and optical interference, thereby improving data transmission efficiency, reducing signal loss and maximising network resource utilisation. 3. system model figure 1 shows a single base station (bs) with eight optical sources, i.e. laser diodes (lds); hence, s = 8. an led system is not as suitable in this situation as lds, which could allow for communication over long distances. there are users at the receiver. each user has eight photodetectors (pds) per user, p = 8. the starpassive-oirs should not be located in the midpoint between bs and clusters, as this would result in a low channel gain. however, in the proposed network, star-passive-oirs is located closer to bs. reconfigurable-star-passive-oirs is utilised to get beyond the restrictions of fso communications provide 360° coverage for both sides, and reach the signal to far-users. fig. 1. proposed system model. with heights of bs (hb), irs (hi), and ue (hu), all users—bs and oirs – are considered in a static position and are distinct from one another. the number of reflecting elements is (ni = 256), and ris has a rectangular form (niv×nih). on–off keying (ook) is used as the modulation type. ook is a binary-level modulation scheme in which the "1" is used to indicate the presence of light, whilst "0" is used to indicate the absence of light in ook. huygens fresnel is employed due to its facilities for the middle and far fields; ray-tracing is better appropriate for the near field. huygens' principle is essential to understanding how signals are designed and routed in star-ris systems. it provides the theoretical basis for how waves propagate and interact with smart surfaces, allowing for improved network performance and ensuring that signals reach the user with high efficiency. a zero mean and variance σ2 additive noise is used to model awgn, the system also accounts for the effects of path loss, shadowing, and scattering, which further impact the received signal quality. the successive interference cancellation (sic) technology is used. it enables increased spectrum utilisation efficiency, improved signal quality, reduced interference between users, support for a larger number of users in the same frequency resource, and reduced decoding error, making it essential for improving the performance of modern communications systems such as noma and 5g networks. the ris is always utilised in a rician channel distribution. it is suitable for at and high altitudes. furthermore, let's say the working area is (wax, way), and the transmit power is 50 mw. the reception noise power is −60 dbm. the transmitted signal between bs’s lds and star irs is denoted by: 𝑋𝑠(𝑡) = 𝛾(√𝑃𝑠𝑥𝑠(𝑡)𝑒 𝑗ωt + 𝐼𝐷𝐶) …(1) each ld's current conversion is represented as 𝛾 [w/a], where γ ε [0,1] and idc are constant dc currents that guarantee the transmitted power's positivity. 𝑃𝑠 is the power transmitted from the laser source s (s from 1 to 8 because we have 8 lds), 𝑥𝑠(𝑡) is the signal sent from the laser source 𝑠 , which is a time function containing the data. ω is an angular frequency of the carrier signal. 𝑋𝑠(𝑡) denotes the ook symbol with zero mean and unit variance from the ld 𝑠, and 𝑋𝑠(𝑡) ∈ rnb ×1. the star ris components receive the signal that is transmitted from the laser sources, the following is a representation of the signal that reaches the star ris surface: 𝑦𝑅𝐼𝑆(𝑡) = ∑ ℎ𝑠𝑋𝑠(𝑡) 8 𝑠=1 …(2) where ℎ𝑠 is the channel between laser source s and the star ris as follows: ℎ𝑠 = (ℎ1, ℎ2, ……… . , ℎ8) 𝑇 …(3) each element on the star ris can either reflect or transmit the signal. the reflected or transmitted signal from element 𝑛 can be represented as: 𝑠𝑅𝑛(𝑡) = 𝑅𝑛 𝑦𝑅𝐼𝑆(𝑡) …(4) batool rafid natiq al-khwarizmi engineering journal, vol. 21, no.2, pp. 106-116 (2025) 110 𝑠𝑇𝑛(𝑡) = 𝑇𝑛 𝑦𝑅𝐼𝑆(𝑡) …(5) where 𝑅𝑛 is the reflection coefficient of element n, 𝑇𝑛 is the transmission coefficient of element n, and the number of elements is 𝑁 = 1 to 256 n elements. the reflection and transmission coefficients of element n are: 𝑅𝑛 = √𝛽𝑛 𝑅 𝑒𝑗𝜙𝑛 𝑅 ...(6) 𝑇𝑛 = √𝛽𝑛 𝑇 𝑒𝑗𝜙𝑛 𝑇 ...(7) where 𝛽𝑛 𝑅 , 𝛽𝑛 𝑇 ∈ [0, 1] are real-valued coefficients satisfying 𝛽𝑛 𝑅 + 𝛽𝑛 𝑇 ≤ 1 , and 𝜙𝑛 𝑅 , 𝜙𝑛 𝑇 ∈[0, 2𝜋) are the phase shifts introduced by element n for the transmitted and reflected signals, ∀𝑛 𝜖{1, 2,· · · , 𝑁}. for passive star-ris elements, the local transmission and reflection coefficients must satisfy the following constraint by the law of energy conservation: |𝑅𝑛 | 2 + |𝑇𝑛 | 2 ≤ 1 ...(8) the near users reach the signal directly from lds in bs, so we null the reflecting signal from starris to near users, the star-ris’s elements only transmit the signal to far users. after being transmitted by the elements of the star ris, the signal reaches distant users through the channel between the star ris and the pds. the signal reaching user 𝑘 with eight photodetectors can be represented as 𝑌(𝑡) = ℛ(∑ ∑ ∑ ∑ 𝑇𝑛 𝑔𝑝 𝑘 256 𝑛=1 8 𝑠=1 8 𝑝=1 ℎ𝑠𝑋𝑠(𝑡)𝑒 𝑗(θs+ϕn+ϕp,k,n) 𝐾 𝑘=1 +�̅�(𝑡)). …(9) sub. (1) in (9): 𝑌(𝑡) = 𝛾ℛ(∑ ∑ ∑ ∑ 𝑇𝑛 𝑔𝑝 𝑘256 𝑛=1 8 𝑠=1 8 𝑝=1 ℎ𝑠(√𝑃𝑠𝑥𝑠(𝑡)𝑒 𝑗(ωt) +𝐾 𝑘=1 𝐼𝐷𝐶)𝑒𝑗(θs+ϕn+ϕp,k,n) + 𝑁(𝑡)), …(10) where 𝑝 refers to the photodetector p of user 𝑘, and 𝑔𝑥,𝑝 𝑘 is the channel between element 𝑛 and photodetector 𝑝 of user 𝑘 . θs is the phase shift added by the channel between laser source s and star ris and ϕs ∈[0, 2𝜋). ϕnis the phase shift added by the transmission process of element n on the star ris and ϕn ∈[0, 2𝜋) , ϕp,k,n is the phase shift added by the channel between element n and photodetector 𝑝 of user 𝑘 and ϕp,k,n ∈[0, 2𝜋) , and np,k(t)is the noise added to user 𝑘. additionally, ℛ is the responsibility of the photodetector of photodetectors 𝑝. the channel between element 𝑛 and photodetector 𝑝 of user 𝑘 is denoted by 𝑔𝑇,𝑝 𝑘 = (𝑟𝑇,𝑘) 𝐻 𝑑𝑖𝑎𝑔(√𝛽𝑇,1𝑒 𝑗𝜙𝑇,1 , …… . , √𝛽𝑇,𝑛𝑒𝑗𝜙𝑇,𝑛)ℎ𝑠, …(11) where ℎ𝑠 is the channel vector between the transmitter and the star-ris elements (eq. [3]), 𝑟𝑇,𝑘= (𝑟𝑇,𝑘,1, 𝑟𝑇,𝑘,2, ……… . , 𝑟𝑇,𝑘,8)𝑇 is the channel vector between the star-ris elements and the receiver 𝑘 in the transmission group, 𝛽𝑇,𝑛 , 𝜙𝑇,1are the amplitude and phase shift for the n-th element of the star-ris. we can write 𝑔𝑇,𝑝 𝑘 as 𝑔𝑝 𝑘. to calculate the sinr, we calculate the signal power as 𝑃𝑘 = 𝐸[𝛾2ℛ2 ∑ ∑ ∑ 𝑃𝑠| ∑ 𝑇𝑛 𝑔𝑝 𝑘256 𝑛=1 8 𝑠=1 8 𝑝=1 𝐾 𝑘=1 ℎ𝑠| 2] = 𝛾2ℛ2 ∑ ∑ ∑ 𝑃𝑠𝐸[|∑ 𝑇𝑛 𝑔𝑝 𝑘256 𝑛=1 8 𝑠=1 8 𝑝=1 𝐾 𝑘=1 ℎ𝑠| 2] = 𝛾2ℛ2 ∑ ∑ ∑ 𝑃𝑠 ∑ |𝑇𝑛 | 2𝐸[|𝑔𝑝 𝑘 |2] 256 𝑛=1 8 𝑠=1 𝐸[8 𝑝=1 𝐾 𝑘=1 |ℎ𝑠| 2], … (12) where |𝑒𝑗(ωt+θs+ϕn+ϕp,k,n)|2 = 1, and 𝑃𝜅 is the signal power for user 𝑘. the interference for each user can denoted as 𝐼𝜅 = 𝛾2ℛ2 ∑ ∑ ∑ 𝑃𝑠 ∑ |𝑇𝑛 | 2𝐸[|𝑔𝑥,𝑝 𝑖 |2] 256 𝑛=1 8 𝑠=1 𝐸[8 𝑝=1 |ℎ𝑠| 2]𝑖≠𝑘 , …(13) where 𝐼𝜅 is the interference power for user 𝑘 from other users, 𝑝 refers to the photodetector p of user 𝑘, 𝑠 refers to the laser source 𝑠, 𝑖 refers to the other users 𝑖 ≠ 𝑘, 𝑇𝑛 𝑡ℎ𝑒 𝑡ℎ𝑒 transmission coefficient of element n on the star ris, 𝑔𝑥,𝑝 𝑖 is the far-field channel between element n and the photodetector 𝑝 of user 𝑖, and 𝑃𝑠is power transmitted from the laser source 𝑠. we use the perfect sic to cancel the interference, if 𝑇𝑛 represents the transmission coefficient for each element on the ris, and 𝑔𝑛,𝑘 represents the channel gain from element n to user 𝑘, the equations for total channel gain are as follows: for user 1 (u1): total gain for u1=∑ 𝑇𝑛 𝑔𝑛,1 256 𝑛=1 for user 2 (u2): total gain for u2=∑ 𝑇𝑛 𝑔𝑛,2 256 𝑛=1 for user 3 (u3): total gain for u3=∑ 𝑇𝑛 𝑔𝑛,3 256 𝑛=1 on the basis of the calculated total channel gain for each user, we can order the users by their channel strength. for example, if the ordering is total gain for u1 > total gain for u2 > total gain for u3, then user u1 receives the strongest signal from the ris. the decoding order is determined as 𝑄1 < 𝑄2 < 𝑄3. thus, interference cancellation begins with user 𝑄1, followed by user 𝑄2, and finally, user 𝑄3. the noise power is 𝑛𝑜𝑖𝑠𝑒 𝑝𝑜𝑤𝑒𝑟 = 𝐸[(�̅�)2] = 𝐸[�̅��̅�𝐻] = 𝐸 {[ 𝑁1 𝑁2 ⋮ 𝑁𝐾 ] [𝑁1 ∗ 𝑁2 ∗ ⋯ 𝑁𝐾 ∗ ]}= [ 𝜎𝑁1 2 0 0 0 0 𝜎𝑁2 2 0 0 0 0 ⋱ 0 0 0 0 𝜎𝑁𝐾 2 ] =𝜎𝑁 2, …(14) where n is an awgn. batool rafid natiq al-khwarizmi engineering journal, vol. 21, no.2, pp. 106-116 (2025) 111 signal-to-interference-plus-noise ratio (sinr): 𝑆𝐼𝑁𝑅 = 𝑠𝑖𝑔𝑛𝑎𝑙 𝑝𝑜𝑤𝑒𝑟 𝑖𝑛𝑡𝑒𝑟𝑓𝑒𝑟𝑒𝑛𝑐𝑒 𝑝𝑜𝑤𝑒𝑟+𝑛𝑜𝑖𝑠𝑒 𝑝𝑜𝑤𝑒𝑟 , …(15) 𝑆𝐼𝑁𝑅 = 𝑃𝑘 𝜎𝑁 2 , …(16) 𝑆𝐼𝑁𝑅 = 𝛾2ℛ2 ∑ ∑ ∑ 𝑃𝑠 ∑ |𝑇𝑛 | 2𝐸[|𝑔𝑝 𝑘 |2] 256 𝑛=1 8 𝑠=1 𝐸[8 𝑝=1 𝐾 𝑘=1 |ℎ𝑠| 2] 𝜎𝑁 2 … (17) the average channel capacity determines how well an fso communication system performs. it is the maximum amount of information that can be transferred in a specific time. the capacity of the ith parallel channel for mimo channels is represented by ci = log2(1 + 𝑆𝐼𝑁𝑅) …(18) then, the total mimo capacity (c) is c= ∑ log2(1 + 𝑆𝐼𝑁𝑅) q i=1 , …(19) which represents the sum of individual capacities of each q information stream. the flowchart of the proposed system setup is shown below: fig. 2. flowchart of the proposed system 4. numerical results and discussions in this section, we present the results of analysing the effect of reconfigurable star-ris location and number of reflective elements on the performance of fso systems. the results aim to clarify the relationship between these key variables and spectrum efficiency, sinr and channel gain. through graphs and quantitative analysis, we demonstrate how performance can be improved using star-ris techniques in wireless communication environments with different challenges. fig. 3. spectral efficiency vs. surface area of starris the graph in figure 3 displays the relationship between surface area and spectral efficiency. when using the star-ris system, spectral efficiency increases remarkably as the reflective surface area increases because increasing the surface area allows more control over the reflected or directed signal, which enhances the signal at the receiver and reduces interference. fig. 4. sinr vs. number of reflecting elements of star-ris in figure 4, we notice that sinr increases continuously as the number of reflecting elements increases. the reason for this is that increasing the batool rafid natiq al-khwarizmi engineering journal, vol. 21, no.2, pp. 106-116 (2025) 112 number of elements allows signals to be directed more accurately to receivers, which increases the received signal strength. star-ris works to reduce noise caused by dispersion and improve the received signal by controlling the phases of the reflected signals. as the elements increase, more constructive interference is achieved between the reflected signals, thus increasing the signal strength and improving the sinr. star-ris proves its efficiency in enhancing signal quality as the number of elements increases, making it an ideal choice for improving the performance of wireless networks. we can use 16 elements for small, experimental, or space-constrained systems and 32 to improve performance in medium environments. the use of 64 elements is common in medium to large deployments to improve beamforming power. for advanced systems that provide good coverage in business environments, 128 elements are used. for high-performance systems such as 5g/6g systems or areas with high interference, 256 elements are used. for systems centred around large areas with great interference and beamforming advantages, 512 elements are used. in advanced model applications such as future 6g, especially in urban areas with a population orientation, 1024 elements are used. in large-scale environments or systems that require excellent chips and high-precision control, 4096 elements are used. for large applications at an advanced level such as stadium coverage, smart cities or space applications, where the available layouts are large and overall performance can be improved, 10,000 elements are used. the choice of number depends on the operating environment (indoor or outdoor), the availability of sufficient space and the performance requirements (such as improving sinr). therefore, the choice depends on the balance between performance and complexity. fig. 5. sinr vs. position of star-ris. figure 5 shows the relationship between sinr and the position of star-ris. for an increase in sinr at the edges, the highest sinr values appear when the star-ris position is close to one of the edges (at values close to 0 or 200 meters). the reason is that placing the star-ris close to the source or receiver increases the routing efficiency and reduces dispersion. for a decrease in sinr in the middle, in the middle of the x-axis (at approximately 100 meters), the sinr values decrease considerably. this decrease occurs because of the increased effect of dispersion and noise when no strong direct path exists between the source and the receiver. the star-ris should be placed close to the source or receiver to achieve the highest sinr and best system performance. fig. 6. channel gain vs. position of star-ris. figure 6 shows the relationship between the channel gain and the position of star-ris. for the highest gain at the ends, the highest channel gain is shown when the star-ris is positioned close to one of the ends (at 0 or 200 meters). the reason for this is that placing the star-ris close to the source or receiver reduces signal loss and increases signal routing efficiency. the lower gain is in the middle because at the middle of the x-axis (approximately 100 meters), the channel gain drops considerably. this decrease indicates increased signal loss due to dispersion and poor signal routing when the starris is placed far from the source and receiver. to achieve the best channel gain, the star-ris should be placed close to the source or receiver rather than in the middle locations. batool rafid natiq al-khwarizmi engineering journal, vol. 21, no.2, pp. 106-116 (2025) 113 5. conclusions this study demonstrated the effectiveness of star-passive-oirs reconfigurable smart surfaces in enhancing the performance of mimo-based fso communication systems. the analysis revealed that increasing the number of reflective elements considerably boosts sinr and spectral efficiency, facilitating improved signal routing and reduced interference. additionally, strategically positioning the smart surface closer to the source or receiver optimises channel gain and minimises signal loss and dispersion. these findings underscore the transformative potential of star-ris technology in overcoming los dependency and mitigating atmospheric disturbances, which are critical challenges in optical communication networks. the results offer valuable insights into designing advanced optical networks, particularly in urban and challenging weather environments. integrating star-ris technology with hybrid (rf/fso) systems presents a promising direction for enhancing the efficiency and reliability of nextgeneration communication networks. future work can integrate star-ris with adaptive control algorithms and ai for real-time optimisation. additionally, reinforcement learning can be applied to determine optimal star-ris placement in multiuser systems whilst optimising resource allocation. ai-driven intelligent elements could further enhance system adaptability by automatically adjusting reflection characteristics based on environmental variations. finally, largescale star-ris implementations with thousands of reflective elements (e.g. 4,096 or 10,000 elements) could enable advanced applications such as smart cities, stadium coverage and satellite communications, thus balancing performance improvements with technical complexity. abbreviations fso rf b5g df owc noma oma sic irs oirs free space optical radiofrequency beyond 5g decode and forward optical wireless communication nonorthogonal multiple access orthogonal multiple access successive interference cancellation intelligent reflecting surface optical intelligent reflecting surface starirs mimo at dofs los nlos bss simultaneously transmitting and reflecting intelligent reflecting surfaces multiple input and multiple output atmospheric turbulence 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https://doi.org/10.1109/tvt.2024.3349543 https://doi.org/10.1109/tcomm.2021.3084637 https://doi.org/10.1109/tcomm.2021.3084637 https://doi.org/10.1109/tcomm.2022.3163767 https://doi.org/10.1109/tcomm.2022.3163767 https://doi.org/10.1109/lwc.2022.3177733 https://doi.org/10.1109/lwc.2020.3034686 https://doi.org/10.1109/jiot.2021.3131771 https://doi.org/10.1109/mwc.001.2100191 https://doi.org/10.1109/lcomm.2021.3082214 https://doi.org/10.1109/lcomm.2021.3082214 https://doi.org/10.1109/jiot.2023.3279357 https://doi.org/10.3390/s22072436 https://doi.org/10.1109/twc.2021.3118225 https://doi.org/10.1109/tvt.2024.3367037 https://doi.org/10.1109/tvt.2024.3349543 ( 2025) 106-116، صفحة 2، العدد21مجلة الخوارزمي الهندسية المجلد بتول رافد ناطق 116 القابل إلعادة التكوين في star-passive-oris تأثير عدد العناصر العاكسة وموقع نظام mimo fso أنظمة 3محمد باقر دولتشاهي، 2األميرلواء فيصل عبد ، *1بتول رافد ناطق المعلومات واالتصاالت/كلية هندسة الخوارزمي/جامعة بغداد/العراق قسم 2،1 إيران /خرم آباد /جامعة لرستان /كلية الهندسة /هندسة الحاسب اآلليقسم 3 batoul.abd2203@kecbu.uobaghdad.edu.iq :البريد االلكتروني * المستخلص القابل إلعادة التكوين في أنظمة االتصاالت الضوئية في الفضاء الحر القائمة على star-passive-oirsهذه الدراسة إلى تحسين أداء نظام رميت mimo أظهرت تقنية لقد : عدد العناصر العاكسة وموقع السطح الذكي. هما تأثير عاملين رئيسيينو. تركز الدراسة على تحليلstar-ris إمكانات كبيرة درجة وتقليل التداخل في 360( وزيادة مكسب القناة، من خالل توفير تغطية بزاوية sinrفي تحسين كفاءة الطيف ونسبة اإلشارة إلى الضوضاء والتداخل ) تكشف النتائج أن زيادة عدد العناصر العاكسة يعزز قوة اإلشارة ويحسن نسبة اإلشارة إلى الضوضاء والتداخل بينما و(. losالبيئات ذات قيود خط البصر ) على التغلب على قيود أنظمة star-risإلى المصدر أو المستقبل األداء األمثل. تسلط الدراسة الضوء على قدرة تقنية يحقق وضع السطح الذكي أقرب fso ئات االتصاالت الالسلكية الحديثة. التقليدية وتحسين أداء الشبكة في بي mailto:batoul.abd2203@kecbu.uobaghdad.edu.iq this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 19, no. 1, march, (2023) p. p. 7080 succinic acid production strategy: raw material, organisms and recent applications in pharmaceutical and food: critical review ramzi a. abd alsaheb* mohammed a. atiya** jaafar kamil abdullah *** azza hashim abbas**** *,**department of biochemical engineering/ al-khwarizmi college of engineering/ university of baghdad/ baghdad/ iraq ****school of mining and geosciences/ nazarbayev university/ kazakhstan *email: ramzi.a@kecbu.uobaghdad.edu.iq atiya@kecbu.uobaghdad.edu.iqemail: ** ***email: drjafar2@basrah-college.edu.iq ****email: azza.hashim@nu.edu.kz (received 28 september 2022; accepted 24 january 2023) 21.000 https://doi.org/10.22153/kej.2023. abstract succinic acid is an essential base ingredient for manufacturing various industrial chemicals. succinic acid has been acknowledged as one of the most significant bio based building block chemicals. rapid demand for succinic acid has been noticed in the last 10 years. the production methods and mechanisms developed. hence, these techniques and operations need to be revised. recently, an omnibus rule for developing succinic acid is to find renewable carbohydrate feedstocks. the sustainability of the resource is crucial to disintegrate the massive use of petroleum based-production. accordingly, systematically reviewing the latest findings of bacterial production and related fermentation methods is critical. therefore, this paper aims to study the latest research and assess the findings statistically comprehensively. the current review attempt is a step toward comprehending all the conditions surrounding succinic acid production from raw materials, microorganisms, and fermentation methods. keywords: succinic acid, food applications, pharmaceutical applications, fermentation process. 1. introduction the dicarboxylic acid succinic acid (c4h6o4) was initially isolated through microbial fermentation in 19th century [1]. amber acid is the most common name for it, however it is also referred to as butanedioic acid. it is created by microbes, animals, and plants [2], although anaerobic fermentation by microbes produces the most of it. succinic acid comes from the fermentation of carbohydrates and is widely employed in chemical markets and companies that produce food [3], biodegradable polymers [4], solvents [5], and pharmaceuticals [6]. additionally, succinic acid is employed as a raw material in the production of numerous industrial products, such as adipic acid [7], aliphatic esters [8], and 1,4-butanediol [9]. table 1 lists the succinic acid's chemical and physical properties. mailto:ramzi.a@kecbu.uobaghdad.edu.iq mailto:atiya@kecbu.uobaghdad.edu.iq mailto:drjafar2@basrah-college.edu.iq mailto:drjafar2@basrah-college.edu.iq mailto:azza.hashim@nu.edu.kz https://doi.org/10.22153/kej.2023.%2001.002 ramzi a. abd alsaheb al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 7080 (2023) 71 table 1, succinic acid properties [10]. (sa) names amber acid, asuccin, bernsteinsaure; kyselina jantarova, dihydrofumaric acid, butanedioic acid iupac name butanedioic acid formula c4h6o4(hoocch2ch2cooh) physical state colorless, odorless white crystals melting point 185-187ᴏc boiling point 235 ᴏc solubility in (solvents) not dissolved in benzene, carbon tetrachloride, carbon sulfide or oil ether; somewhat dissolved in ethanol, acetone and glycerin solubility in (water) soluble molar mass 118.09 specific gravity 1.552 flash point 206 ᴏc density 1.56 g/cm3 vapor density 3.04 acidity (pka) pka1 = 4.2 pka2 = 5.6 stability stable in the ideal conditions occurrence occurs naturally in animal and plant tissues applications pharmaceuticals, agriculture, food and other many industrials succinic acid, an important organic acid found in humans [11], plants [12], and animals [13], plays a vital function in the biological metabolism. four existing markets exist for succinic acid. the greatest of these sectors is the food business, where succinic acid is primarily employed as a flavoring agent [14] and an antimicrobial [15]. the second market is the pharmaceutical industry, where it is a production additive for antibiotics [16], amino acids [17], and vitamins [18]. succinic acid, the third compound, is mostly utilized as a detergent [19], polymer additive [20], surfactant [21], and foaming agent [22]. finally sa use in the paint industry as an ion chelator to prevent corrosion and [23]. (sa) is produced chemically from substrates derived from petroleum, such as butane or benzene, in the consolidated process. however, this approach has disadvantages for the environment and high raw material costs. due to the prospect of employing affordable renewable resources as feedstocks and suggesting sustainable production methods, interest in the fermentative manufacture of (sa) has grown over the past ten years. several bacteria, including actinobacillus succinogenes [25], basfia succiniciproducens [26], mannheimia succiniciproducens [27], and numerous recombinant strains of escherichia coli [28], are capable of producing succinic acid by microbial fermentations. for the industrial use, actinobacillus succinogenes has proven to be a very promising biocatalyst. a. succinogenes' main benefits for producing succinic acid include its capacity to metabolize a wide range of carbon sources, including several monoand disaccharides [29], adequate tolerance to inhibitors [30], pentose sugars, and hexose [31], and sufficient fermentation efficiency even when using renewable feedstock [32]. the primary fermentation byproduct produced by a. succinogenes is succinic acid, with acetic acid, formic acid, pyruvic acid, and ethanol serving as minor byproducts [33]. several studies have concentrated on strain selection, fermentation medium optimization, and feeding management to increase (sa) production [34–36]. in fact, the inhibitory effect of the generated acid on cell development is what is most pressing the production of organic acids via fermentation at an industrial scale, including citric [37], lactic [38], glutamic [39], and gluconic acid [40]. as a result, designing and optimizing the fermenter to produce sa requires a detailed grasp of growth dynamics. ramzi a. abd alsaheb al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 7080 (2023) 72 2. raw materials for succinic acid production lignocellulosic biomass is pretreated to yield fermentable sugars, which are then converted into industrially significant chemicals [41]. various bacteria and fungi are utilized to break down lignocellulosic biomass into glucose monomers. about 250 million tons of lignocellulosic feedstocks are produced annually and come from industrial, agricultural, and forest sources. wastes made of lignocellulosic materials are fairly common and come from both industrial and agricultural sources. lignocellulosic biomass contains a high concentration of cellulose components, including oil palm [42], rice husk [43], wheat straw [44], cassava starch [45], and corn [46]. the following qualities of the raw material must exist for it to be deemed a good substrate for the manufacture of organic acids: ample availability throughout the year, renewable, affordable, high production rate, absence of competing food value, and low level of pollutants. 3. succinic acid applications one of the most well-known coformers is succinic acid, which crystallizes with a number of drugs but is best known for its connection to oxicams [47, 48, 49, 50, 51]. figure 1 presents examples of succinic acid's potential uses. it was acknowledged that succinic acid is a pharmaceutically useful component. (sa) is an endogenous metabolite that is used in a variety of medicinal procedures. when it was revealed that (sa) could be utilized as an intermediary in the synthesis of various compounds with industrial applications because of its linear saturated structure, the succinic acid industry's potential was understood. because it may be used to create a wide range of derivatives that have uses in numerous fields and are beneficial to all forms of life, (sa) is an interesting building block for the business. (sa) has a long history of use as a chemical intermediary in lacquer production, perfume ester production, and medicine. it has also frequently been employed in the food sector as a sequestrant, buffer, and neutralizing agent [52], as well as a known regulator of plant development [53]. after protracted illnesses and injuries, succinates—most frequently potassium succinate and calcium succinate are thought to be beneficial. these are typically used as, antispasmodics, sedatives, antirheoters and contraceptives in medicine. (sa) can also be employed as an antioxidant and a potassium ion inhibitor. (sa) is also a valuable substance for athletes, and as a result, it has the moniker "elixir of youth" [54]. the first and most harmful metabolite of alcohol is acetaldehyde, and these salts have a significant impact on the body's normal capacity to metabolize it [55]. as a result, the patient's resistance to disease, as well as their mental health and ability to concentrate, can be rebuilt. also, esterification is another method for producing a solvent called dimethyl succinate (sa).using constant surface area tablets and powder, many researchers investigated the properties of how the griseofulvin-succinic acid eutectic mixture dissolved [56],[57]. the fusion technique was used to create the solid dispersions, which contained 2.5, 5, 10, 25, and 50% (eutectic composition) of the griseofulvin-(sa) mixture. based on the results, it is hypothesized that the existence of extremely fine griseofulvin crystals is the main cause of the 10% griseofulvin dispersion's rising dissolving rate. a reversed phase ion-suppression high performance liquid chromatography was used in several studies in 1999 to develop an accurate approach for the simultaneous measurement of fumaric, oxalic, and (sa) in tartaric and malic acids for medicinal use high performance liquid chromatography (hplc)[58].the use of extremely diluted per chloric acid in water as the mobile phase reduces the overall time for analysis and lengthens the life of the column, according to the authors. the second feature was good separation of the trace and major constituents in real samples, which makes it easier to determine all the acids of interest simultaneously. in 2016 perform a qualitative analysis of the addition of succinic acid to the various medications to ascertain their pharmacological effects. the development of new medications based on succinic acid; ascorbic acid was researched by the authors [59]. they emphasize the anti-inflammatory, hepato-protective and renal protective effects. while in 2018 ogienko and his group investigated the possibility of using freezedrying to produce medicinal co-crystals when the solubility of the different components vary greatly. in a model system, meloxicam and (sa), co-crystals could form from both pure crystalline phase and solid dispersion with a polymeric carrier [60]. the researchers show that the rate of meloxicam release from its fine solid dispersion in polyethylenglycol co-crystal with succinic acid obtained by freeze-drying was significantly higher ramzi a. abd alsaheb al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 7080 (2023) 73 than the rates of dissolution of i pure meloxicam co-crystals with succinic acid obtained by different variants of freeze-drying (thin film freezing, tff, and spray freeze-drying, sfd), (ii) the powder of meloxicam. figure :1 describe the most potential applications for succinic acid. fig. 1. succinic acid applications [61]. 4. global marketing of succinic acid according to the succinic acid market annually survey [62], the succinic acid market is anticipated to grow from usd 131.7 million in 2018 to usd 182.8 million by 2023, at a predicted cagr of 6.8%. growing demand from the manufacturing, personal care, and food and beverage industries is driving the global market for succinic acid. expanding apac demand and rising use of succinic acid as an alternative to adipic acid in the manufacturing of polyurethane are two factors driving the global market for succinic acid. (sa) is a platform chemical used in the manufacture of several specialty chemicals and is a common chemical intermediate [63]. by 2025, it is expected that the succinic acid market would have grown by 30% annually. this is a result of both its expanding applications and the chemical industry's shift to environmentally friendly products sought through biological pathways. but the two biggest obstacles are the cost of processing and strong market competition [64]. food, cosmetics, lubricants & solvents, medicines, are the key industries that use biobased (sa) as opposed to petroleum-based (sa). applications for plasticizers, polyester polyols, 1,4-butanediol, polybutyrate succinate, due to the dire scenario surrounding the availability of fossil fuels, the risks related with the depletion of petroleum resources, and strict environmental regulations, investments in green chemicals are growing in popularity. these factors will surely hasten the growth of the future market [65]. however, the price of bio-succinic acid and the time-consuming and burdensome downstream processes are the key barriers to market growth. studies show that the newest markets for pigments, resins, and coatings brought in the greatest money in 2013. the greatest application area for 1,4-butanediol, however, is predicted to surpass all others in ten years. this is primarily due to the increased use of bio-succinic acid in the manufacture of 1,4-butanediol [66], a maleic anhydride replacement. instead of using 1 meter per ton of maleic anhydride, it is recommended to utilize 1.0_1.2 meters of bio succinic acid. in electroplating, sa is also employed as an ion ramzi a. abd alsaheb al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 7080 (2023) 74 chelator [67]. succinic acid is typically employed as a flavoring ingredient in the food sector [68]. in several branches of the pharmaceutical sector, it is important as well [69]. table 2, market size and market share for (sa) applications [70]. (sa) applications market size (1000 mt) market share (%) bdo 1 316 52.7 pbs, pbst2 82 13.7 polyester polyols 51 8.5 plasticizer 37 6.2 food 26 4.3 pharmaceutical 21 3.5 alkyd resins 21 3.5 resins, coatings 12 2 cosmetics 12 2 solvents and lubricants 6 1 de-icer solution 3 0.5 others 13 2.2 additionally, succinic acid's use in industrial applications fuels consumer demand for the substance. because pbs/pbst are biodegradable and non-toxic, resistance to heat and more easily processed than other biopolymers, succinic acid is use in them for food packaging [71]. increased disposable income, altering consumer preferences, rising plastics consumption, and expanding packaging sectors are the main factors driving the market for (sa) [72]. these factors have increased demand for non-toxic, biodegradable polyethylene terephthalate (pet) bottles, blood containers, disposable syringes, food containers, and other consumer goods in india, china, japan, and germany, which has fueled the (sa) market's expansion in the polybutylene succinate/poly (butylenes succinate-co-terephthalate) segment. finally, according to the growing demand for succinic acid in all areas of the industry, the demand is expected to reach $200 billion globally. fig. 2. market for succinic acid anticipated to reach $200 billion globally. 5. conclusion this review paper reviewed 72 papers of succinic acid production. the paper thoroughly reviewed numerous substrates, raw materials for succinic acid synthesis. the review indicated 90% of the raw material were successful in a global production of 16,000–30,000 tons. this indicate the economic large-scale deployment of succinic ramzi a. abd alsaheb al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 7080 (2023) 75 acid is attainable. the optimization of production strategy is proved valid by modifying factors as fermentation process, operating conditions, types of raw material and technique of purification. the optimization contributes to the quality and cost reduction. furthermore, it is necessary to promote more raw material and applied research for succinic acid production. 6. references [1] r. rafieenia, “metabolic capabilities of actinobacillus succinogenes for succinic acid production,” brazilian journal of chemical engineering, vol. 31, no. 4, pp. 859–865, dec. 2014, doi: 10.1590/01046632.20140314s00002997. 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[72] h. hu et al., “toward biobased, biodegradable, and smart barrier packaging material: modification of poly(neopentyl glycol 2,5furandicarboxylate) with succinic acid,” acs sustainable chemistry &amp; engineering, vol. 7, no. 4, pp. 4255– 4265, jan. 2019, doi: 10.1021/acssuschemeng.8b05990 (2023) 70-80، صفحة 1عدد، ال19مجلة الخوارزمي الهندسية المجلد رمزي عطا عبد الصاحب 80 ي فيثة استراتيجية إنتاج حمض السكسونيك: المواد الخام والكائنات الحية والتطبيقات الحد األدوية والغذاء: مراجعة نقدية **محمد عبد عطية السراج *رمزي عطا عبد الصاحب ****عباس هاشم عزة ***جعفر كامل عبد هللا قسم الهندسة الكيميائية االحيائية/ كلية الهندسة الخوارزمي/ جامعة بغداد/ بغداد/ العراق،*** ****كلية التعدين وعلوم االرض/ جامعة نزار باييف/ كازاخستان ramzi.a@kecbu.uobaghdad.edu.iq*البريد االلكتروني: atiya@kecbu.uobaghdad.edu.iq**البريد االلكتروني: college.edu.iq-@basrah2drjafar***البريد االلكتروني: azza.hashim@nu.edu.kz****البريد االلكتروني: الخالصة المواد الخاموورقة من إنتاج حمض السكسونيك. استعرض الورق بدقة العديد من الركائز 72استعرضت ورقة المراجعة هذه 16.000ين ب٪ من المواد الخام كانت ناجحة في إنتاج عالمي يتراوح 90لتخليق حمض السكسونيك. أشارت المراجعة إلى أن حسين تادي واسع النطاق لحمض السكسونيك يمكن تحقيقه. تم إثبات صحة طن. هذا يشير إلى أن النشر االقتص 30.000و م التحسين نقية. يساهية التاستراتيجية اإلنتاج من خالل تعديل العوامل مثل عملية التخمير وظروف التشغيل وأنواع المواد الخام وتقن مض نتاج حإلاد الخام والبحوث التطبيقية من الضروري تشجيع المزيد من المو ذلك،في الجودة وخفض التكلفة. عالوة على .السكسونيك mailto:ramzi.a@kecbu.uobaghdad.edu.iq mailto:atiya@kecbu.uobaghdad.edu.iq mailto:drjafar2@basrah-college.edu.iq mailto:azza.hashim@nu.edu.kz al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 17, no. 1, march, (2021) p. p. 1-12 building a high accuracy transfer learning-based quality inspection system at low costs ahmed najah* faiz f. mustafa** wisam s. hacham**** *, **department of automated manufacturing engineering / al-khwarizmi college of engineering/ university of baghdad ***department of mechatronics engineering/ al-khwarizmi college of engineering/ university of baghdad *email: ahmednajah5049@gmail.com **email: faizalrawy@yahoo.com ***email: wisam@kecbu.uobaghdad.edu.iq (received 5 october 2020; accepted 6 december 2020) https://doi.org/10.22153/kej.2021.12.001 abstract products’ quality inspection is an important stage in every production route, in which the quality of the produced goods is estimated and compared with the desired specifications. with traditional inspection, the process rely on manual methods that generates various costs and large time consumption. on the contrary, today’s inspection systems that use modern techniques like computer vision, are more accurate and efficient. however, the amount of work needed to build a computer vision system based on classic techniques is relatively large, due to the issue of manually selecting and extracting features from digital images, which also produces labor costs for the system engineers. in this research, we present an adopted approach based on convolutional neural networks to design a system for quality inspection with high level of accuracy and low cost. the system is designed using transfer learning to transfer layers from a previously trained model and a fully connected neural network to classify the product’s condition into healthy or damaged. helical gears were used as the inspected object and three cameras with differing resolutions were used to evaluate the system with colored and grayscale images. experimental results showed high accuracy levels with colored images and even higher accuracies with grayscale images at every resolution, emphasizing the ability to build an inspection system at low costs, ease of construction and automatic extraction of image features. keywords: backpropagation algorithm, convolutional neural networks, computer vision, deep learning, image classification, quality inspection, transfer learning. 1. introduction traditional layouts, has consistently been a drawback with regards to an excellent product. manual inspection is one of the problems that adds to inferior production. thus, quality inspection (qi) is considered as one of the most important stages in the flow of production, which decides if the item has conformed to the ideal specifications, and fit to be packed or it should be turned into scrap. however, sometimes an item can be reprocessed, in which the damage can be relatively small such as bad surface finish. there are numerous devices that are utilized for qi, contingent upon the necessary inspection task. conventionally, experts took care of the vast majority of those assignments manually, yet those techniques were not proficient. they did not just increase lead times, yet additionally expanded labor and product costs, lower rate of production, and eventually prompted a decrease in income. these days, qi experts and designers, lean towards discovering advanced solutions and new methodologies, to achieve the objective of ideal quality at low expenses, and less consumption of time. inspection is considered as a tool within quality control, which distinguishes the defects mailto:ahmednajah5049@gmail.com mailto:faizalrawy@yahoo.com mailto:wisam@kecbu.uobaghdad.edu.iq https://doi.org/10.22153/kej.2021.12.001 ahmed najah al-khwarizmi engineering journal, vol. 17, no. 1, p.p. 1118 (2021) 2 and assures the level of quality of the product, new methodologies that achieve this task comprise of: inspection systems that are fully automated rather than manual techniques, sensors systems to perform on-line assessment rather than off-line review [1]. since qi is an important stage in the production cycle, attention must be focused on its methodological improvement. to satisfy this demand; advanced technologies such as computer vision (cv), which is one of the artificial intelligence (ai) applications should be used. this technology gives frameworks the ability to interpret the visual world by using deep learning (dl) models and digital images, in which the machine can distinguish and classify the objects. generally, gears are recognized as essential components in any machine, they can be found separated or working together in a gearbox to manipulate the movement of wheels. since gears play an essential role in machinery, they must be manufactured carefully. therefore, optimum quality of gears must be obtained and that can be assured by performing inspection on the produced gears. recent progressions that are concerned with the inspection of gears have broadly utilized mathematical analysis strategies to achieve inspection tasks, for example, detection of plastic gear defects with image processing [2], using wavelet transform for fault detection of planetary gears system [3], detection of gear faults using: morlet-wavelet filter [4], adaptive wavelet threshold de-noising [5] and cosine similarity, wavelet transform and hilbert transform [6]. moreover, gear faults diagnosis using: adaptive impulsive wavelet transform [7], utilizing extreme learning machines and numerical simulation [8], discrete wavelet packet for feature selection of gear faults [9] and inspection of polymer spur gears [10]. advanced technologies like ai and cv are also employed for inspection, such as: using machine vision for spur gears parameters measurement [11], using cv to detect gear tooth number [12], using artificial vision for quality control of spur gears [13], inspection of gear faults using support vector machines (svms) and artificial neural networks (anns) [14], determining fine-pitch gears centers using machine vision [15], gear faults with convolutional neural networks (cnns) [16], gears diagnosis using cnns [17] and inspection of plastic gears using ann and svm based method [18]. ai and cv are also used for other ai inspection related application like: dimensions inspection with machine vision [19], detection of defects in products [20], sugarcane varieties inspection [21], welding inspection [22] inspection of optical laser welding [23] and inspection of aerospace components [24]. vibration signals were the source information in most of the gears related literature mentioned above. therefore, to stay updated with the state of the art, in this research, we present a transfer learning approach that is based on cnns to classify helical gears into healthy and defected classes in attempt to build an accurate, low cost inspection system with automatic features extraction. since this methodology depends on neural networks, manual features extraction was not involved. also, the issue of lacking data is bypassed by using a deep neural network (dnn) that was previously trained on (1.2 million) pictures from imagenet [25]. the parameters from the trained network are imported to the new architecture as the initial segment and an undeveloped neural network fills in as the subsequent part, which accommodates the task of gears faults identification. the subsequent part is trained on test data that comprised of 4000 pictures. as will be demonstrated later, a high accuracy system can be established at low expenses and with no preprocessing methods for the extraction of features. despite the fact that features extraction with the empirical and manual techniques indicated success at various levels, evidently their applicability depends on the features that are extracted from the analysis and may not function on other systems. this method is referred to as a descriptive analysis, in which the analyzer needs to gather process information, assemble a hypotheses on information patterns, and compare the results of the descriptive model with the genuine results to verify the hypotheses [26]. however, it is unsafe to form this type of models, as there is a risk of not modeling some of the variables that scientists and engineers do not include due to lack of information or not understanding the problem [27]. on the other hand, predictive analysis, finds the rules that underlie a phenomenon and establishes a predictive model that limits errors between the desired and the predicted results, with all the involved factors taking into consideration [26]. in contrast with conventional cv techniques, predictive analysis is used by dl to solve issues, which grant dl the advantage of reaching high accuracies with cv applications such as image classification, semantic segmentation and object detection. since dl relies upon dnns that are trained rather than ahmed najah al-khwarizmi engineering journal, vol. 17, no. 1, p.p. 1118 (2021) 3 programmed, applications that depend on this strategy involves basic analysis, calibrating and exploit the huge amount of information that is accessible today within every system. moreover, dl is viewed as a truly adaptable technique as cnns structures can be re-employed for custom data with various applications by training them again, unlike conventional algorithms which are generally intended for a particular domain [28]. the remainder of this paper is organized in the following matter, in section two, cnns are briefly introduced, transfer learning and the proposed architecture, in section three experimental work with training and evaluation are explored, results and discussion are elaborated in section four, and finishing with sections five and six by including the conclusions and the used references respectively. 2. convolutional neural networks a convolutional neural network (or cnn) is one of the dl algorithms that is similar to the neurons connections in the visual cortex of the animals [29]. the cnns are considered as a form of dnns, because they are consist of many layers, as appeared in fig. 1. cnns utilize a linear operation called convolution rather than general multiplication of matrices, which is used by standard anns [30]. they are referred to as the most accurate object detection/recognition algorithm, and like different dnns, they rely upon substantial amounts of data to be trained and give accurate results. this algorithm learns every filter and extract features automatically in contrast to other manual algorithms. as appeared in fig. 1, a typical architecture for a cnn comprises of convolutional layers, an activation function (for example relu), a pooling layer (for example max pooling), and a flattened layer. a single vector is produced by flattening the pooled images, the vector is then used as an input for a fully connected ann for the processing of the features. after training through forward propagation and backpropagation with a number of epochs, the last network will be prepared to give the decision on the image class that is intended to search for. fig. 1. typical cnn architecture. convolutional layer: in mathematics, convolution is an operation that describes the mixing of two information sources. when images are being convolved, the two information sources are the convolution filter (kernel) that is a matrix of (e.g. 5 × 5 or 3 × 3) used for edge detection, sharpening or any other image processing algorithm, and the image pixels matrices, in which there are three that represent each color channel (rgb channels) or one if it is a grayscale image. the two sources convolve into a map of features after applying a dot product between them, as illustrated in fig. 2. ahmed najah al-khwarizmi engineering journal, vol. 17, no. 1, p.p. 1118 (2021) 4 fig. 2. convolution operation. a feature map is the result of the values that are convolved, which highlights an image feature, additionally multiple feature maps can be possessed by a convolutional layer that highlight more than one feature. a neuron's filter window (receptive field) moves over the image, contingent upon the size of the stride. relu: images possesses high non-linearity, and the used network needs to be capable of training on that nature. however, when convolution is applied, it causes an expansion in the input’s linearity. thus, to recover the nonlinearity, an activation function must be used to convert the values of the input, as appeared in equation 1: y = f(∑ (aibi) m i=1 + c), m= 2, 3, 4… ...(1) where (f) is an activation function and y is the output of the neuron. the value of the input in this equation comprise of a single layer perceptron, with (ai) being an input value, (bj) as the connector weight and c representing the value of the bias. this function plays a major role as it increases the non-linearity in the network by multiplying it with the feature maps. this function was utilized in this research as it is capable of training the network at a rate that is higher than any activation function. with relu function, the output value is (z) if the input (z) is positive and 0 if it is not, as it can be seen in equation 2: f(z) = max⁡(z, 0) …(2) where f(z) refers to the output of the activation function. pooling: the output of the convolutional layer (feature maps) is affected by an operation called pooling in which it reduces its dimensionality by decreasing the pixels count (as illustrated in fig. 3). this process results in spatial variance reduction as it removes unimportant details, and this is accomplished by taking the receptive field’s maximum value in case of max pooling, or the average value in case of average pooling, in which both of those operations are used in this research. fig. 3. pooling operation. pooling (equation 3) makes objects recognition much easier in spite of their location in the image, not to mention that diminishing the count of pixels implies there are less parameters to tune, which eliminates overfitting. pooling is fairly like convolution, in the sense that the size of filters, the type of padding and stride must be selected. q(z) = maxzab ⁡⁡ , a, b⁡ϵ⁡rij …(3) where q(z) represents the pooling function and zab is the value of the pixel on the a-th row and b-th column of the filter window (rij). max ahmed najah al-khwarizmi engineering journal, vol. 17, no. 1, p.p. 1118 (2021) 5 pooling focuses on the pixels that are important; in which the pixels with high values are thought of as the ones that are highly activated. according to [31], max pooling showed superior performance when compared with average pooling. it has been utilized in many advanced models [32, 33, 34, 35]. global average pooling: a global average pooling (gap) is a type of pooling that is applied onto the dimensions of the tensor until every dimension is converted to one, in which; this process decreases the trainable parameters and reduces overfitting. a layer of gap has been used in this research instead of a flattening layer, as it showed better performance. 2.1 transfer learning to upscale the performance of a cnn, a number of modifications can be executed like increasing the number of hidden layers or neurons. but that action can cause an increase in the number of trainable parameters, which requires more data. the effect of data amount on the performance of the network is depicted in fig. 4. although large-scale networks performance is superior to different techniques, it still contingent upon the size of training data. but, transfer learning on the other hand can achieve a remarkable performance which can be compared custom cnns using small datasets [36, 37]. by utilizing parameters (knowledge) gained from prior tasks that have a sufficient dataset, transfer learning can be used with insufficient data. instead of using a custom cnn, which would result in issues with its performance. with this methodology, the primary m layers of the network that are already trained, are transferred to another network with untrained layers that would use the new target’s data to train with. generally, the transferred m layers are trained to be features extractors when applied on input data, in which they do not depend on the domain of the application. transfer learning is considered as a solution to the problem of small datasets, as recent studies proved that the main layers (pooling, relu and convolution) for a cnn, serve as a features extraction tool regardless of the target task, as for the rest of the layers (classification and sigmoid), they are associated with task [38, 39]. however, there were insufficient data to build a network from scratch for this research. therefore, transfer learning approach was used to construct a classifier for the purpose of qi, to classify helical gears into damaged and healthy gears. the used trained model was the densenet121, which will be discussed in the following section. fig. 4. performance of learning approaches vs. data size. 2.3 implemented architecture densenet (or dense convolutional neural network) is a huge cnn that comprises 121 layers, created by a group of analysts [40]. the layers in this network are connected in a feed forward arrangement, in order that each layer receives feature maps as inputs that came from previous layers. the feature maps from this layer are also employed as inputs to the following layers. regular cnns with m layers have just m connections, in which there is one connection between every two layers, however densenet has m(m+1)/2 straight connections. the design of the network include 121 layers shaped as 4 dense blocks, comprising convolutional and other layers between for information flow improvement among layers, as illustrated in table 1 [40]. the trainable classification layer is also shown in the table. ahmed najah al-khwarizmi engineering journal, vol. 17, no. 1, p.p. 1118 (2021) 6 table 1, transferred and trainable layers. stage layers transferred 1 (conv.) convolution transferred 2 (pooling) max pooling transferred 3 (dense block 1) convolution × 6 convolution transferred 4 (transition 1) convolution average pooling transferred 5 (dense block 2) convolution × 12 convolution transferred 6 (transition 2) convolution average pooling transferred 7 (dense block 3) convolution × 24 convolution transferred 8 (transition 3) convolution average pooling transferred 9 (dense block 4) convolution × 16 convolution transferred 10 (classification) global average pooling fully connected to be trained (classification) global average pooling 256d fully connected 50 % dropout 1d sigmoid 3. experimental work to collect the data, a phone camera was used to capture 4000 images with different backgrounds for training and validation (fig. 5). the object (helical gear) was taken from the gearbox of an automobile’s transmission unit. the gear serves as an important part for the gearbox dynamics because it transmits power between axles. an open-source web based development environment known as jupyter notebook was used to develop the model and execute different data manipulation operations using python. after feeding the images into the notebook, they were converted to pixels grids that describe the red green blue (rgb) image, then decoded into three dimensional matrices (floating point tensors), because cnns works with three dimensional matrices only. since the densenet121 was trained with images of size (224 x 224) pixels, then it was only reasonable to convert the training images into that size. the final step in preprocessing was to rescale the values of the pixels to values between 0 and 1 by dividing by 255. fig. 5. training images. 3.1 model training training refers to the process of optimizing the weights and biases of a network. optimizers are employed to update the values of those biases and weights continuously until the global minimum point is reached. adam optimizer was the employed optimizer for this research. to estimate the error within the network, binary cross-entropy function was used as the cost function: error = −⁡ 1 m ⁡∑ (r. log(y))m x=1 …(4) where m refers to the number of the model’s training data, r is the goal value and y is the output value (prediction). a (log) term used in the equation to provoke accentuation onto the right predictions. since insufficient data was used for this research, hyperparameters tuning was mandatory to avoid overfitting. 18 trials were performed using an application programming interface called keras, moreover, dummy data was added to the training dataset by using data augmentation method, to upscale the data. dl models consist of millions of parameters that requires a massive amount of calculations. so, to perform those calculations, a large computing power was required especially gpu power, as dl trains faster on gpus than on cpus, a cpu was also needed to perform data augmentation processes. the used gpu was nvidia geforce gtx 1660ti (6gb) and the cpu was intel core i7-9750h. ahmed najah al-khwarizmi engineering journal, vol. 17, no. 1, p.p. 1118 (2021) 7 3.2 model evaluation following the training and validation stage, a final test stage is mandatory to confirm the success of the training. the system had to be tested to evaluate its performance with new data, in the sense that the model should be able to classify unseen gear images, as it was trained to identify the damaged gears from the ones in a healthy condition. therefore, to perform the evaluation, 30 colored images (rgb) were captured by 3 different cameras with differing resolutions of 24, 8 and 5 mega-pixels, to test the model classification accuracy. moreover, 12 grayscale images were also tested to explore the model versatility with images. the whole process was carried out in the same “jupyter notebook” environment, using python to upload and initiate the model, in addition to building a function to convert the inserted images’ size to the standard densenet121’s (224 × 224) pixels. 4. experimental results experiments have been performed to select the proper model for transfer learning, and to show how it is more suitable for small datasets. moreover, system assessment has also been done to explore its limitations and are all shown in the following sections. 4.1 training results the trials results showed how using transfer learning can achieve a better performance than building a model from scratch, in terms of easier implementation. moreover, several encountered issues were observed from the trials that could be discussed. firstly, the issue of training time, which was resolved using more powerful hardware. and that is one of the drawbacks of dl, in which larger systems would require stronger gpus to train at a reasonable rate. but this problem can still be avoided by using online cloud services like (alibaba, aws, google colab…etc.) that provide development environments. the second issue is the high divergence between the losses of training and validation, which convey the significance of the occurring overfitting (as shown in fig. 6), and also that the model is becoming stuck at local minimum points. this is a common issue when dealing with neural networks, especially with insufficient data, the network fails to generalize to the validation set which means the model will not be able to identify unseen information. a bundle of solutions distributed separately and combined within trials were used to prevent overtraining. the effect of the used methods like data augmentation and dropout was observed throughout the trials, as the reduction of training parameters and the addition of dummy data contributed in minimizing the cost function. fig. 6. using vgg16 model in trial 2. last issue encountered was selecting the proper architecture. pre-trained models that were used like xception, vgg16 and resnet50 failed to provide the desired performance; as not every pre-trained model can be used in transfer learning for a custom target dataset. the proper model can either be selected by tediously testing several architectures or by using a selection technique like the one proposed in [41]. ahmed najah al-khwarizmi engineering journal, vol. 17, no. 1, p.p. 1118 (2021) 8 it was observed from trial 14 and up that tweaking the hyperparameters was improving the model, especially with the densenet121 model, as the model showed a noticeable enhancement, conveying the effect of the used architecture and the importance of selecting the proper one. trial 18, reflected an outstanding performance with 98.43% validation accuracy and high convergence between the training and the validations losses (as shown in fig. 7), that means that the network was able to converge towards the global minimum point. fig. 7. using densenet121 model in trial 18. 4.2 evaluation results a. colored images (rgb) to evaluate the model, and test its ability to distinguish the damaged gears from the ones in a healthy condition, it was mandatory to be tested on unseen images; and observe how accurately it will perform. table 2, illustrates the model evaluation results. no. 24 mega-pixels 8 mega-pixels 5 megapixels 1 0.9988 0.9961 0.9770 2 0.9786 0.9763 0.9957 3 0.9974 0.9697 0.9422 4 0.9951 0.9907 0.9602 5 0.9854 0.9936 0.9343 6 1.000 0.9995 0.9883 7 0.9931 1.000 0.9930 8 0.9959 0.9966 0.9914 9 0.9961 0.9911 0.9991 10 0.9801 0.9914 0.9985 sum 9.9205 9.9050 9.7797 % 99.20 99.05 97.79 the accuracy results shown in table 2, implies that the camera resolution had a very small effect on the system performance. moreover, the model memorized and identified the object attributes with high certainty, which means low-resolution cameras can be used for qi systems. those cameras can be purchased at low costs. b. grayscale images more images were tested for evaluation (table 3), but those images were in a black and white format, to see if the model is susceptible to color information. table 3, shows a comparison between grayscale and rgb images. resolution metrics grayscale (%) rgb (%) 24 megapixels accuracy 99.57 91.13 accuracy 99.78 99.71 accuracy 83.77 73.14 accuracy 93.04 90.15 8 megapixels accuracy 99.05 98.46 accuracy 95.28 94.69 accuracy 99.90 99.88 accuracy 98.12 97.63 5 megapixels accuracy 98.84 92.89 accuracy 95.42 84.82 accuracy 70.74 54.21 accuracy 78.46 61.08 evaluation of the grayscale images showed outstanding results in the accuracy measures, as it can be seen from table 3, when compared with the exact image but in rgb format. the accuracy ahmed najah al-khwarizmi engineering journal, vol. 17, no. 1, p.p. 1118 (2021) 9 of the model increased with the black and white format with an average of (5.5% for the 24 megapixels, 0.42% for the 8 mega-pixels and 12.61% for the 5 mega-pixels). moreover, with the last image in the 5 mega-pixel images’ set, the model made a wrong prediction with the colored image, but when the same image was tested in the grayscale format, the model was able to make the right prediction with a rather higher accuracy. according to [42] those results make good sense, as the classification accuracy of a cnn model depends largely on the image lighting, and colored images are susceptible to lighting. the effect of the lighting intensity can be seen in [43] where it was studied thoroughly along with other factors. 5. conclusions in this work, a quality inspection system based on deep convolutional neural networks was proposed to study the effect of utilizing dl with cv as an easier way to build an inspection system and more accurate way to classify objects at a low cost. the used object to be classified was a helical gear. it was planned to train the network to classify it according to its shape state, whether being damaged or not. the system was built using keras framework. a dataset consisted of images of the gears in a healthy and defected state, were used as input for the system. eighteen experiments were conducted using transfer learning and custom cnns to build a highperformance system. employing densenet121 with transfer learning yielded a high accuracy model. the model was trained on the gpu of the computer and took an average of 4 hours for each experiment. the system performance was evaluated on 30 images dataset. they were captured at 3 different resolutions (24, 8 and 5 mega-pixels). the system showed high accuracies of 99.20%, 99.05% and 97.79% respectively. in addition, it was evaluated with 12 grayscale images which showed results that were superior to their exact colored copies. experimental results concluded that using cnns in quality inspection tasks produced some advantages over traditional computer vision techniques regarding accuracy, cost, feature extraction and implementation difficulty, in which high accuracy was achieved at low costs with automatic feature extraction ability and ease of implementation. at the same time, a disadvantage was also noticed about the cnns, as they require large datasets, but that issue was avoided by using transfer learning. nomenclature ai artificial intelligence ai neuron input value ann artificial neural network bj connector weight c bias value cnn convolutional neural network cv computer vision cpu central processing unit dl deep learning dnn deep neural network f activation function f(z) activation function output y neuron output rgb red green blue gap global average pooling gpu graphic processing unit m number of 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(2021) 112، صفحة 1، العدد17دجلة الخوارزمي الهندسية المجلم احمد نجاح النقل بكلف قليلة بتعلم البناء نظام فحص نوعية عالي الدقة مبني على ***حجام خضير وسام سعدي** فائز فوزي مصطفى* نجاحاحمد | كلية الهندسة الخوارزمي| جامعة بغداد*،** قسم هندسة التصنيع المؤتمت ** قسم هندسة الميكاترونكس| كلية الهندسة الخوارزمي| جامعة بغداد* faizalrawy@yahoo.comالبريد االلكتروني: ahmednajah5049@gmail.com :البريد االلكتروني wisam@kecbu.uobaghdad.edu.iq:البريد االلكتروني الخالصة ة القياسيصفات ها بالمواتقدير جودة البضائع المنتجة ومقارنتفيها ، حيث يتم يكل مسار إنتاج تعتبر مرحلة فحص جودة المنتجات من اهم المراحل في بية التي تتطلرق اليدويدية على الطوسائل الفحص التقلالمطلوبة. تحدد األدوات المستخدمة في الفحص وكيفية إجراء الفحص مدى تعقيد النظام. تعتمد أكثر تكون ،ية الكمبيوترة مثل رؤحديثال الفحص الحالية التي تستخدم التقنيات الذكيةفإن أنظمة ،تكاليف مختلفة واستهالًكا كبيًرا للوقت، على العكس من ذلك خراج الخصائصختيار واستتقليدي قائم على رؤية الكمبيوتر كبير جدًا، نظًرا لمشكلة احجم العمل المطلوب لبناء نظام فحص فأن ومع ذلك، ،دقة وكفاءة يدويًا من الصور الرقمية، مما ينتج عنه أيًضا تكاليف العمالة لمهندسي النظام. تم تصميم كلفة منخفضة.تبقة وعاٍل من الد نهًجا متبنى يعتمد على الشبكات العصبية التالفيفية لتصميم نظام لفحص الجودة بمستوى في هذا البحث، تم تقديم لفة. تم صالحة أو تا لى حالةإالنظام باستخدام التعلم بالنقل لنقل الطبقات من نموذج تم تدريبه مسبقًا وشبكة عصبية متصلة بالكامل لتصنيف حالة المنتج اليف قة عالية بتكدستويات ملتقييم النظام. أظهرت النتائج التجريبية وتم استخدام ثالث كاميرات بدقة مختلفة دام التروس الحلزونية كحالة دراسيةاستخ منخفضة واستخراج تلقائي للميزات. mailto:faizalrawy@yahoo.com mailto:ahmednajah5049@gmail.com mailto:wisam@kecbu.uobaghdad.edu.iq this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 19, no. 1, march, (2023) p. p. 2435 mechanical propertiesinvestigation of unidirectional woven carbon fiber reinforced epoxy matrix composite naznaz jalal awla* younis khalid khdir** *,**department of mechanic and energy engineering/ college of technical engineering/ erbil polytechnic university/ erbil, kurdistan region/ iraq *email: naznazshekhbzeny@yahoo.com **email: younis.khdir@epu.edu.iq (received 21 august 2022; accepted 12 december 2022) https://doi.org/10.22153/kej.2023.12.001 abstract in this study, the mechanical properties of an epoxy and unidirectional woven carbon with fiberglass composite were experimentally investigated. when preparing the composite samples, american society for testing and materials (astm)standard was used. tensile, impact and flexural test were conducted to investigate the mechanical properties of the new produced epoxy unidirectional woven carbon and epoxy fiberglass composites. the outcome showed that the strength of the produced samples increased with the increase in the number of unidirectional woven carbon layers added. two methods were utilized: (1) woven carbon composite with glass fiber (2) woven carbon composite). the two methods of composite were compared with each other. the results explained that woven carbon composite had higher mechanical resistance. while in impact test the toughness of the sample increased with adding layers of mixture of fiber glass with unidirectional woven carbon and epoxy. keywords: udwc, epoxy, fiber glass, composite material, mechanical properties. 1. introduction basic composite materials consists of two specific planned materials. the primary benefit of composite materials is that the cost of this kind of materials is low .production of fabric and covered metal instruments heavily relies on various composites [1]. polymer composite materials are the lightest and have the higher young’s modulus comparing with simple structure, even in some cases, the delamination reduces the mechanical properties of the known fiber reinforced compounds[2]. the latest wide-body twin-engine passenger aircraft now increasingly depend on composite materials, while smaller narrow-bodies (e.g. the bombardier c series/airbus a220) are gaining traction. during the production of machine elements, drilling is still necessary for the assembly of sub-sections in the manufacturing of composite aircrafts utilizing mechanical fasteners [3].carbon fiber composites are commonly used. that is due to simplicity of fabrication (even for components with complex shapes) and ease of orientation. the simplicity of fabrication and orientation allows designers to orient stiffness and strength in desired directions. due to these factors, woven fiber composites are often less expensive than other types of composites[4]. for the process of fabricating composite from epoxy resin with fibers, several manufacturing techniques are available. manufacturing techniques such as: manual lay-up technique, distillation, pultrusion filament winding, vacuum bag forming, and resin transfer molding. the hand lay-up technique is preferred for this work, because this technique is simple and powerful[5]. woven fabric composites have advantages mailto:naznazshekhbzeny@yahoo.com mailto:younis.khdir@epu.edu.iq https://doi.org/10.22153/kej.2023.12.001 naznaz jalal awla al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 2435 (2023) 25 such as good integration, compatibility and balanced properties in the fabric plane. although layers of glass woven fabric are preferred in practice, additional layers are required to achieve the desired design strength. this happens in a larger nominal size, which increases the weight of the component/structure. also, the additional layers make the structure commonly known in structural applications e.g. vehicles, aircraft, yachts, and civil structures [6]. bhargav, et, al., (2021) prepared a composite by epoxy in addition with hardner, jute fiber (0/90 oriented) with 760 gsm and titanium dioxide tio2 filler particles [7]also woven jute mat, araldite ly556 epoxy resin and hy951 hardener based on triethylenetetramine ltd (teta) by using hand lay-up technique and this method was adopted by 10:1 epoxy for curing. for an astm d3039-79 they performed tensile testing on a utm with a dumbbell-shaped specimen and a crossover speed of 2 mm/min. for astm d790 bend test was adopted with 1.5mm/min. s2-glass-woven/reinforced epoxy, woven im7-graphite/reinforced epoxy, and woven s2-glass-im7-graphite fiber/epoxy were used for researching purposes by [8]. vacuum assisted resin transfer molding (vartm) technology was used to stack plain-woven fillwarp fabrics together and the composite was manufactured and designed by edo fiber innovations into (101.6 x 101.6) mm sheets, the specimens were cured at 177 °c. a 0.3 mm thickness e-glass fabrics as reinforcement was used by [9] and epoxy with its hardener r101 and h101 as a matrix was used respectively. a rectangular volume was produced for conducting tensile tests using astm d638 (165x19x4mm) and astm d790 (130x12x4mm) for conducting flexural testing. that is to optimize the glass fibers weight fractions. the epoxy resin type (wsr618) as the matrix was used by [10] with benzene dimethylamine as the resin-curing agent and butyl phthalate as the hardener. the layer-bylayer manual stacking process using room temperature vacuum technology and negative pressure curing was used to prevent delamination and cracks between layers. e-glass and carbon fibers were used as reinforcements and epoxy as matrix material by [11]. epoxy resin and tri ethylene tetra amine (teta) hardener were supplied by atul ltd. the production of composites glass/carbon fiber/epoxy based hybrid composites were made by using vacuum bag process trough changing both the reinforcements in terms of weight percentage of 15%, 30%, 45% and 60% fiberglass and carbon fiber in 40% epoxy matrix. the study outcome showed that the mechanical properties of carbon fibers were improved as the fibers reinforcement content increased in the matrix material. [12]used twill -glass fiber, aramid twill fiber, monocoque carbon fiber, unidirectional glass and unidirectional carbon fiber. an epoxy resin (mgs l285) was mixed with a solid (hgs l285) in a volume ratio of 50/100. the compound was made by a manual laying process. the composites were cured at 75°c in an oven after curing at room temperature for 24 h. the steel plates were stacked on the edges of some samples to prevent breakage. the carbon fiber reinforced epoxy compound had better performance than the glass fiber reinforced epoxy compound. that is due to the unidirectional fibers reinforcing the epoxy composite. bhargav and babu, 2021 produced ly556 and hy591 epoxy resin matrix [7], 0.4mm thick bidirectional jute fiber reinforced and sglass fiber in weaving. the fabricating technique was applied by hand. astm-d3039 standard was used for tensile test. for impact test, izod was conducted according to astmd256 standard and three-point bend test according to astm-d790 standard the sample size (80x8x3) mm. the results of this research explained that high strength, toughness and stiffness with the combination of two different levels of fibers play a critical role in automotive and some aerospace application components. in this study, composite materials which consists of epoxy, unidirectional woven carbon and fiber glass are produced by using hand-lay-up technique. also, the mechanical properties are determined by testing the specimens. tests are tensile, impact and flexural. 2. experimental study 2.1 materials in this study, the mechanical properties of carbon/fiberglass unidirectional woven epoxy are experimentally investigated. the naznaz jalal awla al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 2435 (2023) 26 characteristics of each material used are found. 2.1.1 epoxy in this investigation for preparation of the specimens, a type of "master protect 180"epoxy is used (a high build epoxy resin). this type of epoxy consists of two-component part a is as base and part b is as hardener. mixing the two components is very critical by a thin stick for 2-3 minute. table 1 shows the main characteristics of this epoxy resin. table 1, chemical and physical properties of master protect180 epoxy parameter epoxy unit mixing ratio 3:1 % mixing density 1:5 g/cm3 initial cure 24 at 25 hours at℃ final curing 7 at 25 days at℃ working life 40 minute 2.1.2. unidirectional woven carbon (udwc) sikawrap-230 c is a unidirectional woven carbon (udwc) fiber fabric with mid-range strengths is used. sikawrap-230 c is designed for installation using the dry application process. see table 2 for more information about this type of carbon and figure 1(a). table 2, mechanical and physical properties of unidirectional woven carbon parameter udwc unit fiber density 1.82 g/cm3 filament diameter 21-22 μm tensile strength(mpa) 4 gpa tensile modulus (mpa) 230 gpa faber orientation 0 rad limit temperature 5-35 ℃ (a) (b) fig. 1. (a) unidirectional carbon fiber (b) fiber glass. 2.1.3. fiber glass 360 direct roving is a saline compatible with unsaturated polyester, vinyl ester and epoxy resin. 360 direct roving is designed for wire wrap, drip, and weave applications. 360 direct roving is suitable for use in pipes, pressure vessels, grates, profiles and roving woven diverters. also, 360 direct roving is used in boats and chemical storage tanks. see table 3 and figure 1(b). table 3, mechanical and physical properties of fiber glass. parameter fiber glass unit density 2.62 g/cm3 filament diameter 21-22 μm tensile strength 2673 mpa tensile modulus 81126 mpa shear strength 70 mpa limit temperature 15-35 ℃ 2.2. fabrication of composite layers molds are needed. molds are built by 3mm thickness plate has an internal rectangular hole 200mm by 100mm see figure 2. for each test autocad2023is used for the purpose of designing the specimen with different standards, see figure3. a computer numerical control (cnc) machine is employed for cutting the prepared composite specimens. to know the amount needed of epoxy, the mold is filled with epoxy and the percentage of the udwc with fiber glass are calculated . for tensile sample volume = area x thickness …(1) v=2509 x 3 = 7.527 cm3 wight of sample = density of epoxy x volume …(2) =1.5 x 7.527 =11.2905 gm volume= 11.2905 1.5 = 7.527 cm3 5% of udwc = 0.3763cm3 10% of udwc = 0.7527 cm3 15% of udwc = 1.1290cm3 3% of udwc +3% of fiber glass = 0.2258 + 0.2258 = 0.4516cm3 1.5% of udwc = 0.1129cm3 naznaz jalal awla al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 2435 (2023) 27 impact sample volume =16.10 x 0.3=4.83 cm2 wight of sample = 1.5 x 4.83 = 7.245 gm volume= 4.83 cm3 5% of udwc = 0.2415 cm3 10% of udwc = 0.483 cm3 15% of udwc = 0.7245 cm3 3% of udwc +3% of fiber glass = 0.1449 + 0.1449 = 0.2898 cm3 1.5 % of udwc = 0.0725 cm3 flexural sample volume=16.51 x 0.3=4.953cm2 wight of sample =1.5 x 4.953 =7.2495gm volume = 4.833 cm3 5% of udwc = 0.2416 cm3 10% of udwc= 0.4833 cm3 15% of udwc= 0.7249 cm3 3% of udwc +3% of fiber glass = 0.14499 + 0.14499 = 0.2899 cm3 1.5 % of udwc = 0.0724 cm3 fig. 2. the plate mold. (a) (b) (c) fig. 3 autocad drawing a) tensile test sample b) impact test sample c) flexural test sample note, all dimensions are in mm. naznaz jalal awla al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 2435 (2023) 28 hand lay-up technique is used, layer by layer, for fabricating the new proposed composite materials (epoxy udwc and fiber glass)in each sample a different layer from the others is conducted. the first step to start conducting compound material is to prepare the mold, by using on backside a limpid paper and adopting a stick for all sides. then in the second step the front of the mold is cased inside for ease emerging. later on sticks is used for adopting, while in the third step, a layer of epoxy resin is used. after that in the fourth step the second layer which is unidirectional woven carbon is used. these steps are picked out in figure4. these steps are repeated for each composite specimen to produce all the specimens with the same components. one time for each percentage. that is because all the samples are from the same plate. a. first step b. second step. c. third step d. fourth step fig. 4 steps of fabricating composite materials. for the purpose of investigating mechanical properties of samples, three mechanical tests are conducted . the tests are: (1) tensile test (2) impact test (3) flexural test. in the next section the details of the mechanical investigations are explained in details. 3. mechanical tests and results the specimen is labeled. for the mechanical tests, three group of specimens are prepared. group (a1-0, a1-1, a1-2, a1-3, a14, a1-5, and a1-6) for tensile tests, group (b10, b1-1, b1-2, b1-3, b1-4, b1-5, and b2-6) for impact tests and group (c1-0, c1-1, c1-2, c13, c1-4, c1-5, and c1-6) for flexural tests, as indicated in table 4. naznaz jalal awla al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 2435 (2023) 29 table 4, labeling each specimen for the mechanical tests code of composite carbon % fiber glass % layers of composite a1-0, b1-0, c1-0 0 0 epoxy a1-1, b1-1, c1-1 5 0 ep*-c**-ep a1-2, b1-2, c1-2 10 0 ep-c-ep-c-ep a1-3, b1-3, c1-3 15 0 ep-c-ep-ep-c-ep a1-4, b1-4, c1-4 3 3 ep-c-ep-f.g***-ep a1-5, b1-5, c1-5 3 1.5 ep-c-ep-f.g-ep a1-6, b1-6, c1-6 1.5 3 ep-c-ep-f.g-ep noting that *ep refers of epoxy, **c refers to carbon, ***f.g refers to fiber glass 3.1. tensile test in this test, astm d638 standard is utilized. a machine type of xhc-50 ring stiffness tester is employed to test samples. the machine has a software that shows all details about the test. the cross head is 5mm/min, worked with a 100kn load cell with advanced load control. figure 5 shows two samples before testing. fig. 5. specimens tested in tensile. 3.2 impact test in this test, astm d256 is used see figure 6. a machine xjjd-50seriesis used to conduct impact test. charpy impact test is conducted for both metal and plastic. in summary, the details of load and energy are determined. fig. 6. samples tested in impact. 3.3 flexural test this test is done by xww-5kn by software all details are known using astm d790 see figure7. the value of the bending units is determined. seven samples are generated to perform this test and the average quality is calculated; the speed of the crosshead used is 5 mm/min with an extension length of 80 mm. naznaz jalal awla al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 2435 (2023) 30 fig. 7. samples tested in flexural. 4. results and discussion 4.1. tensile test as shown in table 5 and the results of the samples for the tensile test are illustrated in figure8, the highest value of ultimate tensile stress is (168 mpa). that is reached in sample a1-4, which contains a mixture of fiberglass and udwc. on the other hand, adding more layers of udwc to the sample, the tensile strength also increases. this indicates that the difference in stacking sequence has little effect on the tensile strength. in addition, the table shows the modulus of elasticity for each sample and the highest one is a1-4 which contains tertiary epoxy, udwc and fiberglass. this is another indication that shows that the rigid bond between this triple mixture is very high that leads to have the highest modulus of elasticity. figure8 shows the relation between stress and strain, and figure 9 shows samples after testing. from[13] modulus of elasticity can be found as bellow: ϭmax=pmax/(cross section area) …(3) where: ϭ = tensile stress, mpa pmax = maximum load prior to failure, n a = average cross-sectional area, m2 є =∆l/l …(4) where; є = strain, unit less ∆l = change in length (mm) l = original length (mm) young’s modulus od elasticity (e) = σ/ є …(5) where e is in mpa. modulus of elasticity will be found by equation 5, all parameters are known from equation 3& 4 subsequently. table 5, tensile test results composite code load (n) stress (mpa) strain (mm) elongation (%) e (mpa) a1-0 415 10.05 18.02 7.5 0.55 a1-1 3460 74 5.8 0.83 12 a1-2 4260 107 13 1.23 8.2 a1-3 4620 121 23 1.18 5.2 a1-4 7670 168 5 11.77 33 a1-5 1130 23 3.8 9.6 6.05 a1-6 1380 32 2.9 7.89 11.03 fig. 8. stress-strain curves for experimental tensile tests of (a1-0, a1-1, a1-2, a1-3, a1-4, a1-5, and a1-6) 0 25 50 75 100 125 150 175 0 2 4 6 8 10 12 14 16 18 20 22 st re ss (m p a) strain є a1-0 a1-1 a1-2 a1-3 a1-4 a1-5 a1-6 naznaz jalal awla al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 2435 (2023) 31 fig. 9. sample tested in tensile results. 4.2. impact test results table 6 shows the impact testing results of unidirectional woven carbon fiber reinforced epoxy composites, as well as the fiber glass strength. as its seen from the tables the layers of udwc increases the kinematic energy inside the composite samples increases too because of the rigid bond between the epoxy and udwc fibers, samples after testing as shown in figure 10, and the results are shown in the figure 11. the most extreme impact strength is 6.387 j because of having he most layer on it and having the highest toughness compared to others and surely because of having udwc, that gives more ductility to the sample, and the fracture area is less. moreover, both samples b1-2 and b1-4 gives approximately the results of strength. the results show that even adding a layer of fiber glass, can improve the toughness about 3% of the sample. this is a point that can be noted which has a good effect for increasing the toughness of the sample by this small range of fiber glass layers. table 6, impact testing results of unidirectional woven carbon fiber reinforced epoxy composites composite code energy (joule) b1-0 0.103 b1-1 1.488 b1-2 2.757 b1-3 6.387 b1-4 2.059 b1-5 1.578 b1-6 0.867 fig. 10. impact testing samples. naznaz jalal awla al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 2435 (2023) 32 fig. 11. impact toughness for (b1-0, b1-1, b1-2, b1-3, b1-4, b1-5, and b1-6). 4.3 flexural test results the variance of the flexural strength with the percentage of udwc and fiberglass is shown in table 7. the flexure stress increased by this additional percentage, as well as the maximum (100 mpa) in the load (207 n) containing three layers of udwc. the flexural behavior of the composite was increased by the interfacial bond between the udwc and the matrix. and the combination of fiberglass and udwc has an intermediate value of results which is (135n) with (65mpa). also, about modulus of flexure sample c1-1 has the highest value the reason is the bond of rigid strength between udwc and the epoxy resin. fig. 12. samples tested in flexural from [13] flexural modulus will be found by: ef = 𝐿3 𝑚 4 𝑏ℎ3 (6) were; ef = flexural modulus (mpa), l = span length (mm) b = width of the sample (mm) h = thickness of the sample (mm) m= slope (n/mm) 0.103 1.488 2.757 6.387 2.059 1.578 0.867 0 1 2 3 4 5 6 7 b1-0 b1-1 b1-2 b1-3 b1-4 b1-5 b1-6 to u gh n es s (j /m ) naznaz jalal awla al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 2435 (2023) 33 table 4, flexural testing results composi te code load (n) flexure stress (mpa) flexure strain flexural extension flexural modulus (mpa) c1-0 43 20.9 0.064 15 32752 c1-1 118 57 0.054 10 349291 c1-2 141 68 0.033 8.3 252285 c1-3 207 100 0.0292 7 192992 c1-4 135 65 0.062 15 112467 c1-5 29.8 27.37 0.07 20.77 627 c1-6 25.0 22.99 0.06 15.89 3520 fig. 13. stress-strain curves for flexures experimental tests of (c1-0, c1-1, c1-2, c1-3, c1-4, c1-5, and c1-6) 4. conclusion in this study, the mechanical properties of unidirectional woven carbon, fiber glass/ epoxy composite at different rate of layers were studied. the compression between flexural modulus and modulus of elasticity were theoretically found and clearly discussed. the following points can be concluded: 1adding more udwc layers may increase mechanical properties such as tensile stress. 2tensile stress of all specimens varied (decreased) when fiber glass was added to the composite specimens, this variation happened in samples a1-4, a1-5 and a1-6 showed the maximum value when 3% udwc and fiber glass in a1-4 sample when mixed together with epoxy resin. 3the maximum value of young’s modulus of elasticity were achieved within a1-4 specimen the reason is due to multiple layers and having much more composite material on in such as udwc. 4from impact test the sample b1-3 has the highest toughness energy, this increase in toughness because more layers of udwc exists 5the flexural modulus indicates the tendency of the samples. high value of flexural modulus was found with c1-1 sample in which it has the low weight and it has 10% of udwc layers inside. 6the achievement results from the triple mechanical tests shows that as much as the layers of udwc added, the mechanical properties will be increased. 5. references [1] callister, w.d. and d.g. rethwisch, materials science and engineering: an introduction. vol. 9. 2018: wiley new york. 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(2023) 24-35، صفحة 1، العدد19مجلة الخوارزمي الهندسية المجلد نازناز جالل عوال 35 إيبوكسي معززة بألياف الكربون أحادية االتجاهدراسة الخواص الميكانيكية لمركب ر**دنازناز جالل عوال* يونس خالد خ أربيل*،**الكلية التقنية الهندسية/ naznazshekhbzeny@yahoo.com *البريد االلكتروني: younis.khdir@epu.edu.iq**البريد االلكتروني: الخالصة تحضير في هذه الدراسة تم دراسة الخواص الميكانيكية للكربون المنسوج االيبوكسي أحادي االتجاه مع مركب األلياف الزجاجية بشكل تجريبي. عند للتحقق من الخواص واالنحناء(. تم إجراء اختبار الشد والصدمة astmيتم استخدام معيار الجمعية األمريكية لالختبار والمواد ) المركبة،العينات اف مركبات اإليبوكسي أحادية االتجاه المنسوجة المصنوعة من الكربون واأللي لواإليبوكسيمع المنسوج أحادي االتجاه الجديد الكربونمنتج للالميكانيكية كب مع بعضهما الزجاجية. لوحظ أن قوة العينات المنتجة تزداد مع زيادة عدد طبقات الكربون المنسوجة أحادية االتجاه المضافة. إذا قارنت طريقتا المر ومة ميكانيكية فقد لوحظ أن مركب الكربون المنسوج يتمتع بمقا (،مركب الكربون المنسوج الزجاجية،البعض )مركب الكربون المنسوج مع األلياف تزداد صالبة العينة مع إضافة طبقات من خليط األلياف الزجاجية مع الكربون المنسوج بالعكس،وبالتالي في اختبار التأثير يكون العكس بكثير،أعلى أحادي االتجاه واإليبوكسي. mailto:naznazshekhbzeny@yahoo.com mailto:younis.khdir@epu.edu.iq abstract 1. introduction 2. experimental study 2.1 materials 2.1.1 epoxy 2.1.2. unidirectional woven carbon (udwc) 2.1.3. fiber glass 2.2. fabrication of composite layers (a) (b) (c) 3. mechanical tests and results table 4, labeling each specimen for the mechanical tests 3.1. tensile test 3.2 impact test 4. results and discussion 4.1. tensile test table 5, tensile test results 5. references الطلاء الكهربائي بالكروم الصلد وتحسين الخواص بالمعاملات الحرارية الكيمياوية al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 5, no. 4, pp 99-11 4 (2009) انطالء انكهرتائً تانكروو انظهذ وذحسٍٍ انخىاص تانًؼايالخ انحرارٌح انكًٍٍاوٌح نفىالر يُخفض انكارتىٌ (انكرتُه انظهثح) ** أيٍٍ دواي ثاير أحًذ سهىو ػثاش*يُى خضٍر ػثاش اٌغبِؼخ اٌزىٌٕٛٛع١خ /لغُ ٕ٘ذعخ االٔزبط ٚاٌّؼبدْ mukeab2005@yahoo.com* email: email: ahmedsaloom74@yahoo.com ** (received 21 january 2008; accepted 26 august 2009) انخالطح فٟ ٘زا اٌجؾش اعزخذِذ ؽش٠مخ اٌطالء اٌىٙشثبئٟ ثبٌىشَٚ اٌظٍذ، ٟٚ٘ إؽذٜ ؽشائك اٌطالء ثزى٠ٛٓ غطبء ػٍٝ اٌغطؼ، ثبعزخذاَ ؽبِغ ػٍٝ (1:100)اٌىش١ِٚه وّظذس اٌىشَٚ ٚوزٌه ؽبِغ اٌىجش٠ز١ه وؼبًِ ِؾفض ار أْ ٔغجخ ؽبِغ اٌىش١ِٚه إٌٝ ؽبِغ اٌىجش٠ز١ه وبٔذ amp / dm 40)رّذ ػ١ٍّخ اٌطالء ثزغ١ٍؾ وضبفخ ر١بس ِمذاس٘ب . اٌزٛاٌٟ 2 ٌٚفزشاد ص١ِٕخ (ºc(50 – 55 ٚدسعخ ؽشاسح ِؾٍٛي اٌطالء ( . ٌغشع ؽالء٘ب ثبٌىشَٚ اٌظٍذ (substrate) وغج١ىخ أعبط ck15))اعزخذَ اٌفٛالر ِٕخفغ اٌىبسثْٛ ٔٛع . (hr 5 – 1)ِخزٍفخ (2hr)ٌٚفزشح ص١ِٕخ (925ºc)ٌٍؼ١ٕبد اٌّط١ٍخ ثبٌىشَٚ اٌظٍذ ػٕذ دسعخ ؽشاسح (اٌىشثٕخ اٌظٍجخ )رُ أعشاء اٌّؼبٍِخ اٌؾشاس٠خ اٌى١ّ١ب٠ٚخ إر رُ رؾذ٠ذ األؽٛاس اٌجٍٛس٠خ اٌّىٛٔخ ٌطجمخ اٌطالء ثؼذ أعشاء اٌىشثٕخ اٌظٍجخ ٚاٌّزجٛػخ ثبٌزمغ١خ . ٌٍؾظٛي ػٍٝ ؽجمخ ِٓ وبسث١ذاد اٌىشَٚ ٚرُ ل١بط اٌظالدح اٌذل١مخ ٌٍؼ١ٕبد . (cr23c6, cr7c3)ٚاٌّشاعؼخ ثغٙبص ؽ١ٛد األشؼخ اٌغ١ٕ١خ فمذ رُ اٌؾظٛي ػٍٝ وبسث١ذاد اٌىشَٚ ِٓ ٔٛع أِب ثؼذ أعشاء اٌىشثٕخ اٌظٍجخ ٌؼ١ٕبد اٌطالء فمذ اسرفؼذ ل١ُ اٌظالدح .(907hv)اٌّط١ٍخ ثبٌىشَٚ ار رُ اٌؾظٛي ػً طالدح ػب١ٌخ رمذس ( 1276hv)ٚثشىً ٍِؾٛظ ؽ١ش أظٙشد إٌزبئظ أْ أػٍٝ طالدح وبٔذ ٌطجمخ ؽالء اٌىشَٚ ػٍٝ عطؼ اٌفٛالر ِٕخفغ اٌىبسثْٛ وبٔذ .٠ٚؼضٜ عجت اسرفبع ل١ُ اٌظالدح إٌٝ ٚعٛد وبسث١ذاد اٌىشَٚ ػّٓ ؽجمخ اٌطالء وّب )ٌذساعخ خٛاص اٌجٍٝ االٔضاللٟ اٌغبف ٌؼ١ٕبد اٌفٛالر ِٕخفغ اٌىبسثْٛ (pin on disc)اٌمشص – اٌّغّبس اٌجٍٝ ٔٛعاعزخذَ عٙبص ٌٚمذ رُ دساعخ رؤص١ش اٌؾًّ اٌّغٍؾ ػٍٝ ِؼذي اٌجٍٝ ثطش٠مخ اٌفمذاْ ثبٌٛصْ . ٚاٌؼ١ٕبد اٌّط١ٍخ ثبٌىشَٚ اٌظٍذ ٚاٌّىشثٕخ وشثٕخ طٍجخ (اعزٍّذ ٚلذ أظٙشد . (sliding speed( )2.198 m / sec)ٚعشػخ أضالل١خ (n (5 , 10 , 15 , 20 , 25ثبعزخذاَ أؽّبي ػّٛد٠خ ِخزٍفخ ٟ٘ ٚأْ أػٍٝ ِمبِٚخ ٌٍجٍٝ رُ اٌؾظٛي ػ١ٍٙب ثؼذ أعشاء اٌىشثٕخ ، إٌزبئظ اْ ِؼذي اٌجٍٝ ٠ضداد ِغ ص٠بدح اٌؾًّ اٌّغٍؾ ٌٍؼ١ٕبد اٌّط١ٍخ ثبٌىشَٚ ِمبسٔخ ثبٌفٛالر ِٕخفغ اٌىبسثْٛ ثؾبٌزٗ ( 94%)اٌظٍجخ ٌٍؼ١ٕبد اٌّط١ٍخ ثبٌىشَٚ ؽ١ش ٌٛؽع اٌزؾغٓ اٌىج١ش فٟ ِمبِٚخ اٌجٍٝ ٚثّب ٠ؼبدي . اٌّغزٍّٗ chromium electroplating, carbon steel, solid carburizing , wear :انكهًاخ انًفراحٍح انًقذيح .1 رزؼشع اٌؼذ٠ذ ِٓ ِٓ األعضاء إٌٙذع١خ ٌّؼذالد رشغ١ً ػب١ٌخ ِّب ٠ٌٛذ ِؼذي ثٍٝ وج١ش ٌٙزٖ االعضاء ٠ٚغجت ِشبوً وج١شح wear) ٌٚزؾغ١ٓ ِمبِٚخ اٌجٍٝ .فٟ اٌّغبي اٌظٕبػٟ resistance) ٌٟٙزٖ االعضاء اعزخذِذ اٌؼذ٠ذ ِٓ اٌزم١ٕبد اٌز ِٓ اٌّّىٓ اعشائٙب ثطشائك ١ِىب١ٔى١خ ِضً ؽش٠مخ اٌمزف ثبٌىشاد (shot peening) اٚ ؽشائك ؽشاس٠خ وبٌزظ١ٍذ ثبٌؾش ، (induction hardening )[2,1] . وزٌه رغزخذَ رم١ٕخ اٌطالء اٌزٟ رٛدٞ إٌٝ (overlay coating)ثزى٠ٛٓ غطبء ػٍٝ اٌغطؼ اؽذاس رغ١ش فٟ اٌزشو١ت اٌى١ّ١بئٟ ٌٍغطؼ ار ٠ؼذ اٌطالء hard chromium)اٌىٙشثبئٟ ثبٌىشَٚ اٌظٍذ electroplating ) ٖاٌطشائك اٌشبئؼخ االعزخذاَ فٟ ٘ز ِٓ ( abrasion)اٌزم١ٕخ الٔٗ ٠غزخذَ ٌض٠بدح ِمبِٚخ اٌجٍٝ ٚاٌؾه ( performance)ٚرؾغ١ٓ أداء ( corrosion)ٚوزٌه اٌزبوً األعضاء (reclamation)اٌؼذد ،ٚوزٌه ٠غزخذَ فٟ اطالػ وّب اْ اعزخذاَ اٌّؼبِالد اٌؾشاس٠خ . [4,3,1]اٌّزؼشسح رؤدٞ ااٌٝ (thermo chemical treatments)اٌى١ّ١بئ١خ ؽذٚس رغ١ش ثبٌزشو١ت اٌى١ّ١بئٟ ٌٍغطؼ ثبػبفبد ِؼ١ٕخ ثبالٔزشبس ِضً (metallic)ٚاْ ٘زٖ االػبفبد ٠ّىٓ اْ رىْٛ ِؼذ١ٔخ أٚ غ١ش (aluminizing)ٚاالٌّٕخ (chromizing)اٌىشِٕخ ٚاٌىشثٕخ (nitriding)ِضً إٌزشدح (nonmetallic)ِؼذ١ٔخ (carburizing) ٚاٌجٛسدح(boriding.) أْ رطج١ك اٌّؼبِالد اٌؾشاس٠خ اٌى١ّ١بئ١خ ٠ؤدٞ إٌٝ اٌؾظٛي ػٍٝ خبط١ز١ٓ فٟ آْ ٚاؽذ ٟ٘ اٌظالدح اٌؼب١ٌخ ٌٍغطؼ ِّب ٠ؤدٞ إٌٝ رؾغ١ٓ ِمبِٚخ (core)ِغ االؽزفبظ ثّزبٔخ اٌمٍت ٚثظٛسح . [6,5]اٌجٍٝ ٚوزٌه اٌمبث١ٍخ ػٍٝ رؾًّ االعٙبداد اٌؼب١ٌخ ( surface treatments)ػبِخ فؤْ اعزخذاَ اٌّؼبِالد اٌغطؾ١خ ٚاٌطالء ثزى٠ٛٓ غطبء ػٍٝ اٌغطؼ ٠ؤدٞ إٌٝ ص٠بدح فٟ ػّش . [7,3]األعضاء إٌٙذع١خ ثزم١ًٍ ظب٘شرٟ اٌجٍٝ ٚاٌزآوً mailto:mukeab2005@yahoo.com* mailto:email:%20ahmedsaloom74@yahoo.com 114 -99، طفحح 4، انؼذد 5يجهح انخىارزيً انهُذسٍح انًجهذ يُى خضٍر ػثاش (200 9) 100 ٚٔظشا ٌأل١ّ٘خ اٌجبٌغخ ٌٙزا اٌّٛػٛع فمذ عبءد ٘زٖ اٌذساعخ وغضء ِٓ اٌؾٍمبد اٌجؾض١خ اٌزٟ رخض رؾغ١ٓ ِمبِٚخ اٌجٍٝ ٌٍفٛالر ِٕخفغ اٌىبسثْٛ ٚخبطخ فٟ اٌزطج١مبد إٌٙذع١خ وبٌمٛاٌت . ػٍٝ اٌؾبسٚغ١ش٘ب ٚاٌّؼخبد ِٚؼذاد اٌزشى١ً انجسء انؼًهً .2 ذظٍُغ انؼٍُاخ رُ رظ١ٕغ ػ١ٕبد اعطٛا١ٔخ اٌشىً ٌغشع ؽالئٙب ثبٌىشَٚ ٍُِ اٌطٛي ( 20)اٌظٍذ ٚأعشاء اخزجبس اٌجٍٝ ٚوبٔذ أثؼبد اٌؼ١ٕخ فٟ ( اٌّشاعؼخ) ٚرُ أعشاء اٌّؼبٍِخ اٌؾشاس٠خ. ٍُِ ( 10 )ٚاٌمطش 160َ º صُ أعش٠ذ . عبػخ إلصاٌخ االعٙبداد اٌذاخ١ٍخ ( 1)ٌّذح ػ١ٍّخ اٌزٕؼ١ُ اٌشؽت ثبٌّبء ٌٍؼ١ٕبد ثبعزخذاَ ٚسق وبسث١ذ صُ رُ غغٍٙب (1000 500ٚ، 320 )اٌغ١ٍىْٛ ثذسعبد ِخزٍفخ . ثبٌّبء ٚاٌىؾٛي ٚرغف١فٙب ذُظٍف انؼٍُاخ قثم ػًهٍح انطالء رُ اعزخذاَ ػ١ٍّخ اٌزٕظ١ف اٌى١ّ١بٚٞ ٚرٌه ٌٍؾظٛي ػٍٝ عطؼ ٔظ١ف ٚر١ٙئخ عطؼ اٌؼ١ٕخ ٌؼ١ٍّخ اٌطالء ٚلذ أعش٠ذ ٘زٖ :اٌؼ١ٍّخ ػٍٝ ِشاؽً رٕظ١ف لبػذٞ ؽ١ش ٠زُ رغط١ظ اٌؼ١ٕبد فٟ ؽٛع ؽبٚٞ 1 . naoh))ػٍٝ ِؾٍٛي لبػذٞ ؽبس ٘ٛ ١٘ذسٚوغ١ذ اٌظٛد٠َٛ ٚرؾزبط ٘زٖ اٌطش٠مخ إٌٝ رؾش٠ه ٌٍؼ١ٕبد اٌّغّٛسح فٟ اٌؾٛع . ١ٌزُ اصاٌخ اٌذْ٘ٛ ٚاٌض٠ٛد ٚرٌه ثزى٠ٛٓ طٛاث١ٓ رائجخ ثبٌّبء .٠زُ غغً اٌؼ١ٕبد فٟ ؽٛع آخش ؽبٚ ػٍٝ اٌّبء 2 رٕظ١ف ؽبِؼٟ ؽ١ش ٠زُ رغط١ظ اٌؼ١ٕبد فٟ ؽبِغ 3 .اٌّخفف إلصاٌخ اٌظذأ ٚاالٚوغ١ذ (hcl )ا١ٌٙذسٚوٍٛس٠ه .غغً اٌؼ١ٕبد ثبٌّبء 4 طالء انؼٍُاخ تانكروو انظهذ كهرتائٍا رُ رؾؼ١ش ؽٛع اٌطالء اٌّظٕٛع ِٓ ِبدح صشِٛثالعزى١خ ٚثئثؼبد (teflon ) ٚرؼشف رغبس٠ب ثبٌزفptfeٍْٛرغّٝ ٚرُ غغً ؽٛع اٌطالء ثبٌّبء أٚال ثشىً . عُ (10*15*29) إٌٝ اٌّبء (cro3)ع١ذ ثؼذ٘ب رُ إػبفخ لشٛس ِٓ اٚوغ١ذ اٌىشَٚ ِٓ اٌّبء (ٌزش/غُ) 250ِٚضعٙب ع١ذ ثبٌّبصط اٌىٙشثبئٟ ٚثٕغجخ ( h2so4)ٚأػ١ف ٌٍّؾٍٛي أ٠ؼب ؽبِغ اٌىجش٠ز١ه . اٌّمطش ِٓ (ٌزش/ غُ 2.5)أٞ % 1وؼبًِ ِؾفض ٌؼ١ٍّخ اٌطالء ٚثٕغجخ ٠ٍّٚٝء اٌؾٛع ثّؾٍٛي اٌطالء إٌٝ ِغزٜٛ . ؽبِغ اٌىجش٠ز١ه ٚطٛال صالصخ أسثبع اسرفبع اٌؾٛع ٚثبعزخذاَ اٌّغخٓ اٌىٙشثبئٟ صُ . ٌّذح سثغ عبػخ رمش٠جب ºَ (55-50)اٌٝ اٌذسعخ اٌّطٍٛثخ رشثؾ اٌؼ١ٕخ ثبعزخذاَ اٌّبعىبد ثبٌمطت اٌغبٌت ث١ّٕب رشثؾ ٚثؼذ٘ب غّشد اٌؼ١ٕبد فٟ . األلطبة اٌشطبط١خ ثبٌمطت اٌّٛعت اٌّؾٍٛي ١ٌّشس اٌز١بس اٌّطٍٛة ٌٍؾظٛي ػٍٝ ؽالء اٌىشَٚ ٚرزُ ِشالجخ وضبفخ اٌز١بس ٚطٛال إٌٝ ٔٛع ِٓ االعزمشاس٠خ . اٌظٍذ ٚرٌه ٌٍؾظٛي ػٍٝ ؽالء ع١ذ ث١ّٕب رزُ ِشالجخ دسعخ ؽشاسح ِؾٍٛي اٌطالء ثبعزخذاَ اٌّؾشاس ٌىٟ ٠زُ اٌؾفبظ ػٍٝ دسعخ وزٌه رُ ل١بط اٌفٌٛز١خ ثبعزخذاَ . اٌؾشاسح ػّٓ اٌّذٜ اٌّطٍٛة ٚلذ رُ . (.v5.44 ) أصٕبء اٌطالء (voltmeter)ِم١بط اٌفٌٛز١خ ٚؽغت اٌغّه عبػخ(5-1)ؽالء اٌؼ١ٕبد ثفزشاد ص١ِٕخ ِخزٍفخ ٠ٛػؼ خ١ٍخ اٌطالء اٌىٙشثبئٟ ( 1 )ٚاٌشىً . اٌّطٍٛة . اٌّغزخذِخ فٟ اٌجؾش ٠ٛػؾبْ اٌزظ٠ٛش ثبٌّغٙش اٌؼٛئٟ ( 3) ٚ ( 2 )ٚاٌشىالْ ٚثبٌّغٙش االٌىزشٟٚٔ اٌّبعؼ ٌطجمخ اٌطالء ثبٌىشَٚ اٌظٍذ ٌٍفٛالر . ِٕخفغ اٌىبسثْٛ ػٍٝ اٌزؼبلت رسم تخطيطي يوضح خمية الطالء الكهربائي المستخدمة في البحث_ 1_شكل 114 -99، طفحح 4، انؼذد 5يجهح انخىارزيً انهُذسٍح انًجهذ يُى خضٍر ػثاش (200 9) 101 x252 ( من عممية الطالء الكهربائي ساعة5بعد ( )ck15 )نوع الكاربونمنخفض ذ لمفوالد لسطح الطالء بالكروم الصلصورة مجهرية_ 2_شكل a – 636 ساعة 1بعدx b705 ساعة2 بعدx 114 -99، طفحح 4، انؼذد 5يجهح انخىارزيً انهُذسٍح انًجهذ يُى خضٍر ػثاش (200 9) 102 (ck15)لسطح الطالء بالكروم الصلد للفوالذ منخفض الكاربون نوع (sem)بالمجهر اإللكتروني الماسح الصور المجهرية المأخوذة _3_شكل 114 -99، طفحح 4، انؼذد 5يجهح انخىارزيً انهُذسٍح انًجهذ يُى خضٍر ػثاش (200 9) 103 (انكرتُح انظهثح )انًؼايالخ انحرارٌح انكًٍٍائٍح أعش٠ذ ػ١ٍّخ اٌىشثٕخ اٌظٍجخ ٌؼ١ٕبد اٌفٛالر ِٕخفغ اٌىبسثْٛ اٌّطٍٟ ثبٌىشَٚ اٌظٍذ، ؽ١ش ٚػؼذ اٌؼ١ٕبد فٟ صُ اؽىُ (طٕذٚق اٌىشثٕخ )طٕذٚق ِٓ اٌفٛالر اٌّمبَٚ ٌٍظذأ ؽ١ش ٠زىْٛ اٌخ١ٍؾ . غٍمٗ ثبٌط١ٓ اٌؾشاسٞ ثؼذ ٍِئٗ ثخ١ٍؾ اٌىشثٕخ ِٚغؾٛق فؾُ (%70)ثٕغجخ (charcoal )ِٓ اٌفؾُ إٌجبرٟ أػبفخ اٌٝ وبسثٛٔبد (%5)ثٕغجخ (coke powder)اٌىٛن ٌزغ١ٙض االٚوغغ١ٓ اٌالصَ (%25)ثٕغجخ (naco3)اٌظٛد٠َٛ atomic)اٌزٞ ٠ٌٛذ اٌىبسثْٛ اٌزسٞ (co)ٌزى٠ٛٓ أٚي أٚوغ١ذ carbon)رُ ٚػغ اٌظٕذٚق فٟ . ػٕذ رؾٍٍٗ ػٍٝ عطؼ اٌؼ١ٕبد ٌفزشح ص١ِٕٗ ( º 925َ (فشْ اٌّمبِٚخ اٌىٙشثبئ١خ ثذسعخ ؽشاسح . عبػخ2 انًؼايالخ انحرارٌح تؼذ انكرتُح أعش٠ذ ػ١ٍّخ رمغ١خ ِضدٚعخ ػٍٝ اٌؼ١ٕبد اٌّط١ٍخ ثبٌىشَٚ ؽ١ش رُ اٌزغخ١ٓ فٟ اٌّشؽٍخ (وشثٕخ طٍجخ )اٌظٍذ ٚاٌّىشثٕخ ٌّذح سثغ عبػخ ثؼذ٘ب ثشدد ºَ (880 )االٌٚٝ اٌٝ دسعخ ؽشاسح اٌزٞ (core)اٌؼ١ٕبد ثبٌّبء ٚرٌه ٌزؾغ١ٓ اٌج١ٕخ اٌّغٙش٠خ ٌٍمٍت ٌزا رغشٞ . رؼشع اٌٝ افشاؽ فٟ اٌزغخ١ٓ اصٕبء ػ١ٍّخ اٌىشثٕخ ػ١ٍّخ رمغ١خ صب١ٔخ ٌظٙٛس اٌىبسث١ذاد ٚاٌزٟ رزُ ثزغخ١ٓ اٌفٛالر اٌٝ أعش٠ذ . ٌّذح سثغ عبػخ صُ اٌزجش٠ذ ثبٌّبءºَ (780)دسعخ ؽشاسح ٌّذح عبػخ صُ اٌزجش٠ذ ºَ (200 )ػ١ٍّخ ِشاعؼخ فٟ دسعخ ؽشاسح ثبٌٙٛاء الصاٌخ االعٙبداد اٌذاخ١ٍخ اٌزٟ رزىْٛ ِٓ عشاء ػ١ٍّخ . اٌزمغ١خ انًىاد انًسرخذيح ٚؽغت (ck15 ) رُ اعزخذاَ فٛالر ِٕخفغ اٌىبسثْٛ ٔٛع العزخذاِٗ فٟ اٌزطج١مبد (din17210)اٌّٛاطفخ االٌّب١ٔٗ اٌظٕبػ١خ اٌزٟ رؾزبط اٌٝ عطؼ طٍذ ِمبَٚ ٌٍجٍٝ ِغ االؽزفبظ ٚاٌفٛالر ػجبسح ػٓ لؼجبْ اعطٛا١ٔخ . ثمٍت ؽشٞ ِمبَٚ ٌٍظذِبد رُ اعشاء اٌفؾض اٌزشو١ت . ِزش )6 (ٍُِ ٚثطٛي (19) لطش٘ب spectrometer ))اٌى١ّ١بٚٞ ثبعزخذاَ عٙبص اٌزؾ١ًٍ اٌط١فٟ ٔٛع analysis ,arl . ٠ج١ٓ ٔزؤئظ اٌزؾ١ًٍ اٌى١ّ١بئٟ (1)ٚاٌغذٚي (.15ck)ٌٍفٛالر ِٕخفغ اٌىبسثْٛ ٔٛع ، 1جذول ( ck15)َرائج انرحهٍم انكًٍٍاوي نهفىالر يُخفض انكارتىٌ َىع s% p% mn % si% c% انؼُظر wt% انقًٍح انقٍاسٍح 0.18 – 0.12 0.4 0.6 – 0.3 0.035 0.035 انقًٍح انفؼهٍح 0.14 0.4 0.38 0.02 0.03 انفحىطاخ واالخرثاراخ .3 حساب يسايٍح انطالء ٠ّىٓ ؽغبة ِغب١ِخ اٌطالء ِٓ خالي ؽغبة اٌّغبؽخ اٌغضئ١ٗ (area fraction ) اٌزٟ رشغٍٙب اٌّغبِبد اٌّزٌٛذح ٔز١غخ ٌؼ١ٍّخ ؽ١ش رُ اػزجبس اٌّغبِبد وش٠ٚخ اٌشىً رمشث١ب ِٓ خالي . اٌطالء [:8]اٌؼاللخ اٌزب١ٌخ ِغبؽخ = ِظ = اٌّغبؽخ اٌغضئ١خ ٌٍّغبِبد اٌّغبؽخ اٌى١ٍخ/ اٌّغبِبد (1) ... s niri 2 ِظ = -: ؽ١ش اْ ri : ٔظف لطش اٌّغبِخ ni : ػذد اٌّغبِبد s : اٌّغبؽخ اٌى١ٍخ ( roughness inspection)فحض انخشىَح رُ ل١بط اٌخشٛٔخ اٌغطؾ١خ ٌٍؼ١ٕبد ثؼذ أعشاء اٌزٕؼ١ُ (grinding ) ٌٙب ٚلجً اٌطالء ٚوزٌه ٌٍؼ١ٕبد ثؼذ اٌطالء ، ِٚمبسٔخ رٌه ثؼذ أعشاء اٌىشثٕخ اٌظٍجخ ٌٍؼ١ٕبد اٌّط١ٍخ ثبعزخذاَ دلزٗ (perthometer –sgp) عٙبص ل١بط اٌخشٛٔخ ٔٛع (0.001 µm) .٠ج١ٓ ل١ُ اٌخشٛٔخ اٌغطؾ١خ ٌٍؼ١ٕبد (2)ٚاٌغذٚي .اٌّفؾٛطخ ، 2 جذول ٌثٍٍ انخشىَح انسطحٍح نهؼٍُاخ انًفحىطح rt (m) (max) ra(m) (average) specimen 1.53 0.08 ck 15 as received 1.75 0.09 ck 15 as deposited 114 -99، طفحح 4، انؼذد 5يجهح انخىارزيً انهُذسٍح انًجهذ يُى خضٍر ػثاش (200 9) 104 1.88 0.16 ck15 hard (cr) + carburized 114 -99، طفحح 4، انؼذد 5يجهح انخىارزيً انهُذسٍح انًجهذ يُى خضٍر ػثاش (200 9) 105 plating thickness حساب سًك انطالء calculation أخزد ِمبؽغ ػشػ١خ ِٓ اٌؼ١ٕبد اٌّط١ٍخ ثؼذ لطؼٙب ثبعزخذاَ ٚرُ رٕؼ١ّٙب . ( wire cutter machine)ِبوٕخ اٌمطغ ٔٛع ( 120, 320, 1000,500)ثبعزخذاَ اٚساق رٕؼ١ُ ثذسعبد ِخزٍفخ اٌؼ١ٕبد ثبعزخذاَ ( polished)ثؼذ رٌه طمٍذ . ػٍٝ اٌزٛاٌٟ لّبػ طمً خبص ِغ أعزؼّبي ِؼغْٛ اٌّبط ٚثؾغُ ؽج١جٟ صُ . ِب٠ىشْٚ ثؼذ٘ب غغٍذ اٌؼ١ٕبد ثبٌّبء ٚاٌىؾٛي ٚعففذ (1.5) ثبعزخذاَ ِؾٍٛي االظٙبس (etching)أعش٠ذ ػ١ٍّخ االظٙبس ( 98%)ؽبِغ إٌزش٠ه ِغ (2%)اٌّىْٛ ِٓ (nital)ا١ٌٕزبي ٌٍؼ١ٕبد اٌّط١ٍخ رُ فؾض اٌّمطغ اٌؼشػٟ صُ . وؾٛي ِض١ٍٟ ٌؾغبة عّه ( carlzeiss jena)ثبٌّغٙش اٌؼٛئٟ ٔٛع ٚرُ اعزخذاَ ػذعخ خبطخ رؾزٛٞ ػٍٝ ِم١بط أٚ رذس٠ظ. اٌطالء (scale ) ؽ١ش ٠زُ ٚػغ أٚ . ِغ رشر١جٗ ِب٠ىشِٚزش خبسع١خ أٔطجبق اٌّم١بط ػٍٝ ؽجمخ اٌطالء اٌّشاد ل١بعٙب صُ ػجؾ اٌّم١بط ٚوبٔذ . ِٓ ا١ٌّىشِٚزش ٚأخز اٌمشاءح ِٓ اٌزذس٠ظ اٌذاخٍٟ ٌٍؼذعخ ٔزؤئظ ل١بط عّه ؽجمخ اٌطالء اٌىشَٚ اٌظٍذ ػٍٝ عطؼ اٌفٛالر amp / dm 40)اٌّىشثٓ ػٕذ وضبفخ ر١بس 2 ، ٚدسعخ ؽشاسح ( ٠ٛػؼ اٌض٠بدح (3)ٚاٌغذٚي . º َ( 55 (50ِؾٍٛي اٌطالء إٌبرغخ فٟ عّه ؽجمخ ؽالء اٌىشَٚ اٌظٍذ ِغ اٌفزشح اٌض١ِٕخ .ٌٍطالء ، 3 جذول ٌىضح ذغٍر سًك انطالء نهؼٍُاخ يغ انفررج انسيٍُح نهطالء سًك انطالء (m ) زيٍ انطالء ( hr ) 25 1 50 2 70 3 105 4 150 5 microاخرثار انظالدج انًجهرٌح انذقٍقح hardness as) رُ ل١بط اٌظالدح اٌّغٙش٠خ ٌٍؼ١ٕبد اٌّط١ٍخ ثبٌىشَٚ deposited ) َٚاٌؼ١ٕبد اٌّط١ٍخ ثبٌىشَٚ اٌزٟ رُ وشثٕزٙب ثبعزخذا vicker)عٙبص ل١بط اٌظالدح ف١ىشص , s) ثؼذ اعشاء ػ١ٍّخ ٚاْ اٌؾًّ اٌّغزخذَ . رؾؼ١ش٠خ ػٍٝ اٌؼ١ٕبد ِٓ رٕؼ١ُ ٚطمً ٚاظٙشد ؽجمخ ؽالء . غشاَ (160)وبْ صبثزب ٌىً اٌؼ١ٕبد ٚ٘ٛ أِب ثؼذ . (hv872-905)اٌىشَٚ اٌظٍذ طالدح رزشٚاػ ث١ٓ اعشاء اٌىشثٕخ اٌظٍجخ ٌٍؼ١ٕبد اٌّط١ٍخ ثبٌىشَٚ فمذ وبٔذ (hv1276 .) wear testاخرثار انثهى رُ اعزخذاَ عٙبص اٌجٍٝ االٔضاللٟ اٌغبف ِٓ ٔٛع اٌّغّبس ػٍٝ ٌزٕف١ز اخزجبس اٌجٍٝ ٚػٕذ ظشٚف ( pin – on -disc )اٌمشص ٚلذ رُ أخز١بس دساعخ رؤص١ش اٌؾًّ اٌّغٍؾ ػٍٝ ػ١ٕبد . ِخزٍفخ :-اٌجؾش ٚوبٔذ ظشٚف االخزجبس وبالرٟ ( n( 25,20,15,10,5االؽّبي اٌّغزخذِخ 1 ( min 30)صِٓ االخزجبس ٘ٛ 2 67hrc( counter face)طالدح اٌمشص اٌّٛاعٗ 3 (5cm)ثؼذ اٌؼ١ٕخ ػٓ ِشوض اٌذٚساْ 4 (r.p.m 510)اٌغشػخ اٌذٚسا١ٔخ ٌٍمشص -5 the) رُ ؽغبة ِؼذالد اٌجٍٝ ثبعزخذاَ اٌطش٠مخ اٌٛص١ٔخ weighting method ) ْاٌزٟ رؼّٕذ ؽغبة اٌفمذاْ ثبٌٛص . ٚرٌه ثٛصْ اٌؼ١ٕخ لجً االخزجبس ٚثؼذٖ ث١ّضاْ ؽغبط سلّٟ رٞ ٚٔز١غخ . (mettler ae200)ِٓ ٔٛع ( غُ 0.0001)ؽغبع١خ اٌزغ١ش فٟ اٌٛصْ اٌّفمٛد ػٍٝ ِغبفخ االٔضالق ٠ّىٓ ؽغبة ِؼذي : [ 9 ] عُ ٚوّب ِٛػؼ فٟ اٌّؼبدٌخ ا٢ر١خ/ ٚرؾذ٠ذٖ ثـ غُ اٌجٍٝ wear rate = ntr w   2 …(2) δw = w1-w2 …(3) :ؽ١ش رّضً δw : ُاٌفشق ثبٌٛصْ ٌٍؼ١ٕخ لجً االخزجبس ٚثؼذ االخزجبس ، غ w1 : ُٚصْ اٌؼ١ٕخ لجً االخزجبس ، غ w2 :ُٚصْ اٌؼ١ٕخ ثؼذ االخزجبس، غ r : ُٔظف اٌمطش ِٓ ِشوض اٌؼ١ٕخ إٌٝ ِشوض اٌمشص، ع n : ثبٌذل١مخ/ ػذد دٚساد اٌمشص ، دٚسح t :صِٓ االخزجبس ، دل١مخ انفحض وانرظىٌر تانًجهر انضىئً وانًجهر ( sem)االنكرروًَ انًاسح ِٚ٘ٛغٙش االثؾبس (mef2) اعزخذَ اٌّغٙش اٌؼٛئٟ ٔٛع ٌغشع فؾض ( universal research microscope)اٌؼبَ as)اٌؼ١ٕبد اٌّط١ٍخ ثبٌىشَٚ ٚثذْٚ أٞ ػ١ٍّخ رؾؼ١ش٠خ deposited ). اِب اٌؼ١ٕبد اٌّط١ٍخ ثبٌىشَٚ اٌزٟ اعش٠ذ ٌٙب ػ١ٍّخ اٌىشثٕخ اٌظٍجخ فمذ رُ رؾؼ١ش٘ب ٌٍفؾض اٌّغٙشٞ ثبعشاء ٚرُ ثؼذ اعشاء . ػ١ٍّبد رؾؼ١ش٠خ ِٓ رٕؼ١ُ ٚطمً ٚاظٙبس اخزجبس اٌجٍٝ دساعخ ٚفؾض اٌغطؼ اٌّزؼشس ٔز١غخ ٌٙزا االخزجبس وّب رُ اعزخذاَ . ٚثذْٚ اعشاء أٞ ػ١ٍّبد رؾؼ١ش٠خ ٌٍؼ١ٕبد اٌّغٙش االٌىزشٟٚٔ اٌّبعؼ (cambridge sem ) ٔٛع (s.240 ) ٌذساعخ ؽجٛغشاف١خ .أعطؼ اٌجٍٝ ِٚالؽظخ األصبس إٌبرغخ ػٓ أخزجبس اٌجٍٝ ray diffractionانرحهٍم تحٍىد االشؼح انسٍٍُح analysis x ٌجؼغ اٌؼ١ٕبد (xrd) أعشٞ اٌزؾ١ًٍ ثؾ١ٛد االشؼخ اٌغ١ٕ١خ اٌّط١ٍخ ثبٌىشَٚ ثؼذ اعشاء ػ١ٍّخ اٌىشثٕخ اٌظٍجخ ٌٙب ٌّؼشفخ اٌّشوجبد ٚاالؽٛاس إٌبرغخ ثؼذ اٌىشثٕخ اٌظٍجخ ٌطجمخ اٌطالء ، ٚرٌه ثبعزخذاَ عٙبص اٌفؾض ثؾ١ٛد االشؼخ اٌغ١ٕ١خ اٌزبثغ اٌٝ اٌششوخ اٌؼبِخ ٌٍّغؼ اٌغ١ٌٛٛعٟ ٚاٌزؼذ٠ٓ ٔٛع 114 -99، طفحح 4، انؼذد 5يجهح انخىارزيً انهُذسٍح انًجهذ يُى خضٍر ػثاش (200 9) 106 (philips p / n 1840) ٟٚثبعزخذاَ ٘ذف ٔؾبعٟ ثطٛي ِٛع (cuk = 1.54 aº.) انُرائج وانًُاقشح .4 َرائج انؼٍُاخ انًطهٍح تؼذ اجراء ػًهٍح انكرتُح رُ اعشاء اٌىشثٕخ اٌظٍجخ ٌٍؼ١ٕبد اٌّط١ٍخ ثبٌىشَٚ اٌظٍذ ٚرٌه ٌٍؾظٛي ػٍٝ ؽجمخ عطؾ١خ ِظٍذح ِٓ وبسث١ذاد اٌىشَٚ (cr23c6 , cr7c3) وّب اصجززٙب ٔزبئظ اٌفؾض ثؾ١ٛد االشؼخ ِٚٓ اٌّؼشٚف اْ اٌطالء . (12)اٌغ١ٕ١خ وّب ِج١ٓ فٟ اٌشىً tensile)اٌىٙشثبئٟ ثبٌىشَٚ اٌظٍذ ٠ٌٛذ اعٙبداد شذ٠خ stresses) ػٍٝ اٌغطؼ رمًٍ ِٓ اٌخٛاص ا١ٌّىب١ٔى١خ ٌطجمخ ؽالء ٌزا فؤْ اعشاء اٌىشثٕخ اٌظٍجخ ٌطجمخ ؽالء اٌىشَٚ عٛف . اٌىشَٚ residual compression )٠ٌٛذ اعٙبداد ػغط١خ ِزجم١خ stresses ) عٛف رؤدٞ اٌٝ رؾغٓ فٟ خٛاص ؽجمخ اٌطالء [11] . انظالدج انًجهرٌح انذقٍقح ل١ّخ ٌٍظالدح ػٕذ اٌغطؼ أظٙشد ؽجمخ اٌطالء ثبٌىشَٚ اٌظٍذ hv)ٚلذ ٚطٍذ اٌظالدح اٌٝ . (hv872 -907)رزشٚاػ ث١ٓ ٚوبْ . ثؼذ اعشاء اٌىشثٕخ اٌظٍجخ ٌٍؼ١ٕبد اٌّط١ٍخ ثبٌىشَٚ (1276 5) )ِب٠ىشْٚ ثؼذ اعشاء اٌطالء ٌّذح (150)عّه ؽجمخ اٌطالء ٠خزٍف عّه ؽجمخ اٌطالء ثبٌىشَٚ اٌظٍذ ؽغت ؽ١ش. عبػخ اٌزطج١ك إٌٙذعٟ ٠ٚزشاٚػ عّه اٌطالء ثبٌىشَٚ اٌظٍذ ث١ٓ ٚلذ رظً طالدح ؽجمخ اٌطالء . [11] ِب٠ىشْٚ (500-2.5) ٌٍٚؾظٛي ػٍٝ اٌظالدح . )hv 1000)ثبٌىشَٚ اٌٝ أوضش ِٓ اْ . [2]اٌّطٍٛثخ ٠غت اٌزٕغ١ك ث١ٓ دسعخ اٌؾشاسح ٚوضبفخ اٌز١بس ٔزبئظ عّه اٌطالء ٚاٌزٟ رُ اٌؾظٛي ػ١ٍٙب ثزغ١١ش صِٓ اٌطالء ِٓ iwai )[12] (ٚرضج١ذ وضبفخ اٌز١بس رزفك ِغ ٔزبئظ اٌجبؽش خالي اعزخذاِٗ ٌظشٚف ؽالء ِّبصٍخ ٌظشٚف ؽالء اٌجؾش ٠ٛػؼ اٌزغ١ش فٟ عّه اٌطالء ثبٌىشَٚ (4) ٚاٌشىً . اٌؾبٌٟ اٌظٍذ ػٍٝ عطؼ اٌفٛالر ِٕخفغ اٌىشثْٛ ِغ اٌفزشح اٌض١ِٕٗ . ٌٍطالء انرركٍة انًجهري تؼذ انكرتُح انظهثح وانًؼايالخ انحرارٌح انالحقح اْ اعشاء اٌىشثٕخ ٌٍفٛالر ِٕخفغ اٌىبسثْٛ ٠ؤدٞ اٌٝ اٌؾظٛي ػٍٝ رشو١ت ِغٙشٞ ِىْٛ ِٓ ؽٛس اٌّبسرٕغب٠ذ ِغ ٚعٛد شجىخ وبسث١ذ٠خ ِٓ اٌغّٕزب٠ذ (martensite)اٌذل١ك رخزفٟ ػٕذ اٌزٛغً اٌٝ داخً اٌؼ١ٕخ ِّب ٠ذي اْ اٌطجمخ اٌغطؾ١خ لذ اْ . [13,5].رشجؼذ ثبٌىبسثْٛ ٌٚؼّك ِؼ١ٓ عشاء ػ١ٍّخ اٌىشثٕخ رؾش٠ش ػٕظش اٌىبسثْٛ ثبٌؾبٌخ اٌزس٠خ ِٓ اٌٛعؾ اٌّىشثٓ ِٚٓ صُ رالِظ رساد اٌىبسثْٛ ػٍٝ عطؼ اٌفٛالر اٌّطٍٟ ثبٌىشَٚ صُ ٠زُ رغٍغً رساد اٌىبسثْٛ داخً ؽجمخ اٌطالء ٚارؾبد٘ب . اٌظٍذ ِغ اٌىشَٚ ٌزى٠ٛٓ وبسث١ذاد اٌىشَٚ ثبٌؼ١ٍّبد االٔزشبس٠خ ٚاٌزٟ ِٚٓ خالي ِالؽظخ اٌشىً . ادد اٌٝ ص٠بدح عّه اٌطجمخ اٌّظٍذح اٌزٞ ٠ٛػؼ اٌزشو١ت اٌّغٙشٞ ٌٍؼ١ٕبد اٌطالء ثؼذ اٌىشثٕخ (5) ٚاٌزٟ (cr23c6 , cr7c3 )ٚرى٠ٛٓ وبسث١ذاد اٌىشَٚ ِٓ ٔٛع وزٌه . (massive carbides)رؼذ ِٓ اٌىبسث١ذاد اٌؼخّخ فٟ اٌج١ٕخ اٌّغٙش٠خ ٌطجمخ ؽالء (cracks)٠الؽع ٚعٛد اٌشمٛق .اٌىشَٚ ٔز١غخ ٌؼ١ٍّخ اٌىشثٕخ اٌظٍجخ plating porosityيسايٍح انطالء رؼذ اٌّغب١ِخ اؽذٜ ػ١ٛة اٌطالء ألٔٙب رؼًّ ػٍٝ رم١ًٍ ِمبِٚخ اٌزآوً ػالٚح ػٍٝ أٙب رمًٍ ِٓ اٌخٛاص ا١ٌّىب١ٔى١خ االخشٜ ٚرزىْٛ اٌّغبِبد . وّمبِٚخ اٌىالي ٌٍغضء اٌّطٍٟ ثبٌىشَٚ (pores) ٔز١غخ ٌؼ١ٛة ِٛػؼ١خ(localized defects ) :-[1]رزشىً فٟ ِشؽٍخ عبثمخ لجً اٌطالء ٚاٌزٟ رزؼّٓ .فٟ اٌغج١ىخ األعبط (surface inclusion)شٛائت اٌغطؼ 1 ٚاٌشمٛق (crevices)ػ١ٛة اٌغطؼ ٚاٌزٟ رزؼّٓ االخبد٠ذ 2 (cracks) ٚإٌمش(pits) ٚاٌخذٚػ(scratches.) ٚرٕغت ٘زٖ اٌؼ١ٛة االٔفخ اٌزوش اٌٝ ػ١ٍّبد اٌزٕظ١ف ٚاٌزغط١ظ (pickling) ٚػ١ٍّبد اٌزشى١ً ػٍٝ اٌجبسد وبٌذسفٍخ ، (rolling). وّب رغبُ٘ لذسح ػ١ٍّخ اٌطالء فٟ رغط١زٙب ٌٍغطؼ (cover surface) ٚثبٌشغُ ِٓ . فٟ اٌزؤص١ش ػٍٝ اٌّغب١ِخ ( porous structure)ِغبٚا اٌّغب١ِخ اال اْ اٌزشو١ت اٌّغبِٟ ِٓ اٌّّىٓ اْ ٠ىْٛ رٚ فبئذح ٚرٌه فٟ رطج١مبد اٌجٍٝ ٚاٌزٟ ٚخبطخ فٟ اعطٛأبد (lubrication)رزطٍت رض١٠ذ اْ اٌزشو١ت اٌّغبِٟ ٌطجمخ اٌطالء ٠غُٙ فٟ ص٠بدح . اٌّؾشوبد ار رؾزفع ؽجمخ اٌطالء ثبٌّض٠ذ (wettabillity)لبث١ٍخ اٌزشؽ١ت .[2]( initial lubrication)ثؼذ اعشاء اٌزض١٠ذ األٌٟٚ ٚاٌزٞ ٠ٛػؼ اٌزغ١ش فٟ اٌّغب١ِخ (6)٠ٚالؽع ِٓ اٌشىً ار ٠الؽع . اٌغضئ١خ ٌٍّغبِبد ِغ عّه ؽجمخ اٌطالء ثبٌىشَٚ اٌظٍذ اْ اٌّغبؽخ اٌغضئ١خ ٌٍّغبِبد رضداد ثض٠بدح عّه اٌطالء ؽ١ش ( 150)ػٕذ عّه ؽالء (،(6.5 %)ثٍغذ إٌغجخ اٌّئ٠ٛخ ٌٍّغبِبد . (15ck) ٔٛعِب٠ىشْٚ ٌٍفٛالر ِٕخفغ اٌىبسثْٛ انظالدج انًجهرٌح انذقٍقح ثؤْ ل١ّخ اٌظالدح ػٕذ اٌغطؼ وبٔذ (7) ٠الؽع ِٓ اٌشىً (1276 hv) ٌٍفٛالر ِٕخفغ اٌىبسثْٛ ثؼذ اعشاء اٌىشثٕخ ث١ّٕب وبٔذ ل١ُ اٌظالدح اٌذل١مخ . اٌظٍجخ ٌٍؼ١ٕبد اٌّط١ٍخ ثبٌىشَٚ (701 hv )ٌفٛالر ِٕخفغ اٌىبسثْٛ ثؼذ اعشاء اٌىشثٕخ ي ٠ٚؼضٜ ٘زا االسرفبع فٟ . اٌظٍجخ ٚاٌّزجٛػخ ثبٌزمغ١خ ٚاٌّشاعؼخ ل١ُ اٌظالدح اٌٝ رى٠ٛٓ وبسث١ذاد اٌىشَٚ ٚوزٌه وبسث١ذ اٌؾذ٠ذ (fe3c) ٠ٚالؽع اٌض٠بدح اٌؾبطٍخ . [6]فٟ اسػ١خ ِبسرٕغب٠ز١خ ٍُِ(0.6)، ار ثٍغذ (case depth)فٟ ػّك اٌطجك اٌّظٍذح ٌٍفٛالر ِٕخفغ اٌىبسثْٛ ثؼذ اعشاء اٌىشثٕخ اٌظٍجخ ٌٍؼ١ٕبد ػٕذ اعشاء ِب٠ىشْٚ ( 0.5)اٌّط١ٍخ ثبٌىشَٚ اٌظٍذ، ث١ّٕب ثٍغذ ٚ٘زا ٠ؼٛد اٌٝ اسرفبع ٔغجخ . اٌىشثٕخ فمؾ ٌٍفٛالر ِٕخفغ اٌىبسثْٛ اٌىبسثْٛ ٚثبٌزبٌٟ ص٠بدح اٌؼ١ٍّبد االٔزشبس٠خ ٚرى٠ٛٓ وبسث١ذاد ( cameron)ٚ٘زٖ إٌزبئظ رزفك ِغ ِب لبَ ثٗ اٌجبؽش . اٌىشَٚ ار اشبس اٌٝ اْ اػبفخ ػٕبطش اٌغجه فٟ ػ١ٍّخ اٌىشثٕخ ، [14] . رؤدٞ اٌٝ رى٠ٛٓ وبسث١ذاد ِؼمذح ِضً وبسث١ذاد اٌىشَٚ 114 -99، طفحح 4، انؼذد 5يجهح انخىارزيً انهُذسٍح انًجهذ يُى خضٍر ػثاش (200 9) 107 114 -99، طفحح 4، انؼذد 5يجهح انخىارزيً انهُذسٍح انًجهذ يُى خضٍر ػثاش (200 9) 108 طثقح انطالء طثقح انطالء طثقح انطالء b 252ساػح 2 تؼذ x c 252 ساػح 3 تؼذ x a 252ساػح 1 تؼذ x (ck15)وضح انرغٍر فً سًك طثقح طالء انكروو انظهذ ػهى سطح انفىالر يُخفض انكارتىٌ َىع انظىر انًجهرٌح انرً خ _ 4_شكم 114 -99، طفحح 4، انؼذد 5يجهح انخىارزيً انهُذسٍح انًجهذ يُى خضٍر ػثاش (200 9) 109 ( 25µm)سًك انطالء a ،(ck15) انثٍُح انًجهرٌح نؼٍُح يطهٍح تانكروو تؼذ أجراء انكرتُح انظهثح نهفىالر يُخفض انكارتىٌ طىر _ 5_شكم b سًك انطالء( m µ50) cr7c3 cr23c6 cr7c3 cr23c6 x 160 b x 160 a 114 -99، طفحح 4، انؼذد 5يجهح انخىارزيً انهُذسٍح انًجهذ يُى خضٍر ػثاش (200 9) 110 انظىر انًجهرٌح انرً ذىضح زٌادج انًساحح انجسئٍح نهًساياخ يغ زٌادج زيٍ انطالء تانكروو انظهذ ػهى سطح انفىالر يُخفض انكارتىٌ َىع _ 6_شكم ((ck15 x 160 ْ b a 400 ساعة 1 بعد x a 400 ساػح1تؼذ x b 400 ساػح5تؼذ x 114 -99، طفحح 4، انؼذد 5يجهح انخىارزيً انهُذسٍح انًجهذ يُى خضٍر ػثاش (200 9) 111 ثى ذًد كرتُره ( ساػح5نًذج ) انًطهً تانكروو ck15َرائج انظالدج انًجهرٌح نهفىالر يُخفض انكارتىٌ َىع _ 7_شكم 0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2 2.4 distance form surface mm carburized steel hard chromium playing & carburized steel (group e) h v 114 -99، طفحح 4، انؼذد 5يجهح انخىارزيً انهُذسٍح انًجهذ يُى خضٍر ػثاش (200 9) 112 ثى ذًد ( ساػح5نًذج )انًطهً تانكروو ck15ذأثٍر انحًم انؼًىدي انًسهظ ػهى يؼذل انثهى األَسالقً انجاف نهفىالر يُخفض انكارتىٌ َىع _ 8_شكم كرتُره دراسح َرائج أجراء اخرثار انثهى االَسالقً انجاف دراسح ذاثٍر انحًم انؼًىدي انًسهظ ػهى يؼذل 4.6.1 انثهى رُ دساعخ رؤص١ش اٌؾًّ اٌؼّٛدٞ اٌّغٍؾ ػٍٝ ِؼذي اٌجٍٝ ٌؼ١ٕبد اٌفٛالر وّب اعزٍّذ ٚثؼذ ؽالئٙب ثبٌىشَٚ اٌظٍذ ٚوزٌه ثؼذ اعشاء عبػخ ( 2) ٌفزشح ص١ِٕٗ ºَ ( 925)ثذسعخ ؽشاسح اٌىشثٕخ اٌظٍجخ ( sliding speed)ٌؼ١ٕبد اٌطالء ثبعزخذاَ عشػخ أضالل١خ ٚرُ اعزخذاَ خّغخ اؽّبي فٟ ٘زا . (m / sec 2.198)ِمذاس٘ب ٌج١بْ رؤص١ش٘ب ػٍٝ ِؼذي اٌجٍٝ (n 25,20,15,10,5)اٌجؾش ٟ٘ ( 8)٠ٚالؽع ِٓ خالي اٌشىً . ِغ ثمبء اٌّزغ١شاد األخشٜ صبثزخ ثؤْ ِؼذي اٌجٍٝ ٌؼ١ٕخ اٌفٛالر ِٕخفغ اٌىبسثْٛ ثؾبٌزٙب اٌّغزٍّخ ٠ضداد ِغ ص٠بدح اٌؾًّ اٌّغٍؾ ٚاٌغجت أٗ ثض٠بدح اٌؾًّ اٌّغٍؾ اٌؾبطً ٌمُّ (plastic deformation)٠ضداد اٌزش٠ٛٗ اٌٍذْ إٌزٛءاد اٌغطؾ١خ ٌٍؼ١ٕخ ِّب ٠ؤدٞ اٌٝ ص٠بدح ِغبؽخ اٌزالِظ ار اْ ػ١ٍّخ اٌزظبق . [15] اٌؾم١م١خ ث١ٓ اٌغطؾ١ٓ إٌّضٌم١ٓ إٌزٛءاد ٌغطؾٟ اٌزالِظ رؼزّذ أػزّبداً وج١شاً ػٍٝ ِمذاس اٌؾًّ اٌّغٍؾ، فؼٕذِب ٠ىْٛ اٌؾًّ اٌّغٍؾ ل١ٍالً فؤْ االرظبي ٠ؾظً ٌزٌه عٛف ٠ىْٛ ػؼ١فبً . فمؾ ػٕذ اػٍٝ لُّ إٌزٛءاد اٌغطؾ١خ ألٔٗ اصٕبء ػ١ٍّخ االٔضالق رزىْٛ ؽجمخ سل١مخ ِٓ االٚوغ١ذ رؼًّ ٠غطٟ (protective surface film)ثّضبثخ غشبء عطؾٟ ٚاق اعطؼ االٔضالق ِّب ٠ؤدٞ اٌٝ لٍخ ؽظٛي اٌزالِظ ِب ث١ٓ اٌغطؾ١ٓ إٌّضٌم١ٓ ِٕٚغ ؽظٛي االرظبي اٌّؼذٟٔ اٌّجبشش ِب ٚثٙزا عٛف رىْٛ اٌمٛح اٌالصِخ ٌمض . ث١ٓ ٔزٛءارّٙب اٌغطؾ١خ ٚفظً اٌزشاثؾ اٌؾبطً ِب ث١ٓ ٔزٛءاد اٌغطؾ١ٓ الً ِٓ لٛح رشاثؾ رساد اٌّؼذْ ٔفغٗ ٚثبٌزبٌٟ ٠ٕزظ ػٓ رٌه أخفبع ِؼذي اِب ػٕذ ص٠بدح اٌؾًّ اٌّغٍؾ ف١ؾذس رىغش ٌغشبء . [16]اٌجٍٝ االٚوغ١ذ ٚرٌه ثغجت ٘شبش١زٙب ار أٗ ٠مزف خبسط اٌغطٛػ االٔضالل١خ اٌّؾزىخ ٌىً ِٓ اٌؼ١ٕخ ٚاٌمشص اصٕبء ػ١ٍّخ االٔضالق لٛٞ (metallic junction)ِّب ٠ؤدٞ ؽظٛي ارظبي ِؼذٟٔ ف١ّب ث١ٕٙب ٠غؼً اٌمٛح اٌالصِخ ٌمض ٔزٛاءرّٙب اٌّزظٍخ اػٍٝ ِٓ لٛح رشاثؾ رساد ِؼذْ اٌؼ١ٕخ ٔفغٙب، ِّب ٠ؤدٞ رٌه اٌٝ خٍغ ٚفظً دلبئك ِؼذ١ٔخ ِٓ عطؼ اٌؼ١ٕخ ِؤد٠بً ثبٌٕز١غخ اٌٝ ص٠بدح . ِؼذي اٌجٍٝ ؽظٛي اٌجٍٝ االٚوغ١ذٞ ػٕذ االؽّبي (8)٠ٚزؼؼ ِٓ اٌشىً اٌٝ اٌجٍٝ (mild wear)اٌم١ٍٍخ ٚاٌزؾٛي ِٓ آ١ٌخ اٌجٍٝ اٌطشٞ ٚرزفك ٘زا اٌض٠بدح فٟ ِؼذي اٌجٍٝ . (severe wear)اٌشذ٠ذ [17]( eyre)ٌٍفٛالر ِٕخفغ اٌىبسثْٛ ِغ ِب اشبس ا١ٌٗ اٌجبؽش . ِٓ اْ ص٠بدح اٌؾًّ اٌّغٍؾ رؤدٞ اٌٝ اصد٠بد ِؼذي اٌجٍٝ اٌزؾغٓ اٌٛاػؼ فٟ ِمبِٚخ اٌجٍٝ (8)٠ٚزؼؼ ِٓ اٌشىً )ٌٍفٛالر ِٕخفغ اٌىبسثْٛ ػٕذ اعشاء اٌىشثٕخ ٚثذسعخ ؽشاسح 925 )َº عبػخ ٚؽالئٗ ثبٌىشَٚ اٌظٍذ وٙشثبئ١بً ٚوزٌه (2) ٌّٚذح .ػٕذ اعشاء اٌىشثٕخ ٌؼ١ٕبد ؽالء اٌىشَٚ اٌظٍذ اٌزمغ١خ )اْ وشثٕخ اٌفٛالر ِٚٓ صُ ِؼبٍِزٗ ؽشاس٠بً ادد اٌٝ خفغ ِؼذي اٌجٍٝ ثغجت رى٠ٛٓ شجىخ ِٓ (ٚاٌّشاعؼخ ث١ّٕب اظٙشد اٌؼ١ٕبد . فٟ اسػ١خ ِبسرٕغب٠ز١خ (fe3c)اٌغّٕزب٠ذ ( 925) اٌظٍذ ٚاٌّىشثٕخ وشثٕخ طٍجخ فٟ دسعخ اٌّط١ٍخ ثبٌىشَٚ َº عبػخ رؾغٕبً افؼً فٟ ِمبِٚخ اٌجٍٝ ِمبسٔخ ( 2) ٌّٚذح ٠ٚؼضٜ رٌه اٌٝ اسرفبع طالدح ؽجمخ . ثبٌؼ١ٕبد اٌّىشثٕخ فمؾ cr23c6 ) ٔٛع اٌىشَٚ اٌظٍذ ٚرى٠ٛٓ شجىخ ِٓ وبسث١ذاد اٌىشَٚ , cr7c3) ِغ رى٠ٛٓ ث١ٕٗ ِبسرٕغب٠ز١ٗ ٚاٌزٟ ٠ٕزظ ػٕٙب ص٠بدح ٌٍطجمبد اٌغطؾ١خ ِٚٓ صُ أٔخفبع ِؼذي اٌجٍٝ ِغ اصد٠بد اٌظالدح ٠ظً ِشؽٍخ ٠جذا ػٕذ٘ب اٌطالء ثبٌزمشش اٌؾًّ اٌّغٍؾ ؽزٝ (spelled off) صُ ا١ٙٔبس اٌطالء ٚاسرفبع وج١ش فٟ ِؼذالد ِٓٚ ٌزا فؤْ اٌؼبًِ اٌؾبعُ ٕ٘ب ٘ٛ عّه ؽجمخ اٌطالء . [1]اٌجٍٝ ثبٌىشَٚ اٌظٍذ فؼٕذ ص٠بدح ٘زا اٌغّه رضداد ِمبِٚخ اٌجٍٝ اٚ ِب ٌزا فمذ وبٔذ . (durability)٠ظطٍؼ ػ١ٍٗ ثمبث١ٍخ رؾًّ اٌطالء (150)ٔزبئظ ِؼذالد اٌجٍٝ ٌٍؼ١ٕبد اٌّط١ٍخ ثبٌىشَٚ راد عّه ٚػٕذ فؾض . ِب٠ىشْٚ ٟ٘ االفؼً ِٓ ث١ٓ اٌّغب١ِغ االخشٜ اٌؼ١ٕبد اٌّزؤصشح ثبٌجٍٝ ثؼذ االخزجبس ثبٌّغٙش اٌؼٛئٟ ٌٛؽع ٚعٛد دلبئك أٚوغ١ذ٠خ ٍِزظمخ ثبٌغطؼ ٟٚ٘ رّضً ؽطبَ اٌجٍٝ . )9)األٚوغ١ذٞ ٚوّب ِٛػؼ فٟ اٌشىً دراسح طىتىغرافٍح اسطح انثهى 4.6.2 ٌمذ رُ دساعخ اٌغطؼ اٌّزؼشس ِٓ اٌجٍٝ ٚالؽّبي ِخزٍفخ ٚؽبٌخ ؽ١ش رج١ٓ اٌظٛس اٌفٛرٛغشاف١خ اٌّؤخٛرح ثبٌّغٙش . ػ١ٕبد ِخزٍفخ ارغبٖ خطٛؽ اٌجٍٝ ِغ رى٠ٛٓ ؽطبَ (sem)االٌىزشٟٚٔ اٌّبعؼ اْ رىْٛ اٌشمٛق اٌزٟ رىْٛ ػّٛد٠خ ػٍٝ ارغبٖ االٔضالق . اٌجٍٝ ٚاٌزمبئٙب ِغ ثؼؼٙب اٌجؼغ ِٚغ خطٛؽ اٌجٍٝ ِّب عجت أفظبي ٚخٍغ ؽجمبد سل١مخ ِٓ عطؼ اٌؼ١ٕخ ِىٛٔخ ثزٌه دلبئك ؽطبَ اٌجٍٝ ٚاٌزٞ ٠ج١ٓ اٌزشٖٛ اٌؾبطً ٌغطؼ ، (10)وّب ِٛػؼ فٟ اٌشىً ػ١ٕخ اٌفٛالر ِٕخفغ اٌىبسثْٛ ثؾبٌزٙب اٌّغزٍّخ ِغ ظٙٛس اٌؾفش اٌشىً اِب (. 25n )ٚاالخبد٠ذ فٟ عطؼ اٌؼ١ٕخ ٚػٕذ رغ١ٍؾ ؽًّ ف١ٛػؼ رىْٛ ؽجمخ ِٓ ؽطبَ اٌجٍٝ ٌطجمخ اٌطالء ٚاٌزٟ (11) رؼًّ ػٍٝ خفغ ِؼذي اٌجٍٝ فٟ ؽبٌخ اٌؼ١ٕبد اٌّط١ٍخ ثبٌىشَٚ .اٌظٍذ أْ اٌغطؼ اٌّزؤصش ثبٌجٍٝ ٌٍفٛالر اٌّىشثٓ وشثٕخ طٍجخ ث١ّٕب ٠الؽع ، اٌؾبطً فٟ اٌفٛالر اٌّغزٍُفمؾ ٠ىْٛ الً رشٛ٘ب ِمبسٔخ ثبٌزشٖٛ . ار رىْٛ االخبد٠ذ اٌّزىٛٔخ ِغ ارغبٖ االٔضالق conclusionsاالسرُراجاخ .5 رىْٛ (xrd)أظٙشد ٔزبئظ اٌفؾض ثؾ١ٛد األشؼخ اٌغ١ٕ١خ .1 ػّٓ ؽجمخ اٌطالء (cr7c3, cr23c6 )وبسث١ذاد اٌىشَٚ .ثؼذ أعشاء اٌىشثٕخ اٌظٍجخ ٚاٌّزجٛػخ ثبٌزمغ١خ ٚاٌّشاعؼخ ص٠بدح ػّك ٚطالدح اٌطجمخ اٌّظٍذح ٌٍفٛالر اٌّطٍٟ ثبٌىشَٚ .2 اٌظٍذ ٚاٌّىشثٓ وشثٕخ طٍجخ أدد اٌٝ أٔخفبع ِؼذي اٌجٍٝ ثّمذاس أوجش ِمبسٔخ ثبٌفٛالر اٌّىشثٓ فمؾ ٚػٕذ ع١ّغ األؽّبي . اٌّغٍطخ فٟ أخزجبس اٌجٍٝ عٍٛن اٌجٍٝ ٌٍؼ١ٕبد اٌّىشثٕخ فمؾ ٚاٌؼ١ٕبد اٌّط١ٍخ ثبٌىشَٚ .3 ٚاٌّىشثٕخ ٠خزٍف ػّب ٘ٛ ػ١ٍٗ فٟ ؽبٌخ اٌفٛالر ثؾبٌزٗ اٌؾًّ اٌّغٍؾ)اٌّغزٍّخ أر رظٙش صالس ِٕبؽك فٟ ِٕؾٕٟ اٌجٍٝ اٌطشٞ ٚاٌجٍٝ االٔزمبٌٟ ٚاٌجٍٝ اٌشذ٠ذ فٟ (ِؼذي اٌجٍٝ . ؽبٌخ اٌفٛالر إٌّخفغ اٌىبسثْٛ ثؾبٌزٗ اٌّغزٍّٗ أدد ػ١ٍّخ اٌىشثٕخ اٌظٍجخ ٌٍؼ١ٕبد اٌّط١ٍخ ثبٌىشَٚ إٌٝ رؾغٓ .4 ِمبسٔخ ثبٌفٛالر ( %94)وج١ش فٟ ِمبِٚخ اٌجٍٝ ٠ؼبدي . ِٕخفغ اٌىبسثْٛ ثؾبٌزٗ اٌّغزٍّٗ 114 -99، طفحح 4، انؼذد 5يجهح انخىارزيً انهُذسٍح انًجهذ يُى خضٍر ػثاش (200 9) 113 114 -99، طفحح 4، انؼذد 5يجهح انخىارزيً انهُذسٍح انًجهذ يُى خضٍر ػثاش (200 9) 114 انحًم – a، ياٌكروٌ وزٌادج انرشىٌه يغ زٌادج انحًم نؼٍُح انفىالر يُخفض انكارتىٌ (150) انًُطقح انًرأثرج تانثهى نطثقح طالء انكروو سًك _ 9_شكم (15n) b – انحًم(20n )c – انحًم(25n ) اتجاه االنزالق ارغبٖ االٔضالق x 252 a x 252 c x 252 b 114 -99، طفحح 4، انؼذد 5يجهح انخىارزيً انهُذسٍح انًجهذ يُى خضٍر ػثاش (200 9) 115 114 -99، طفحح 4، انؼذد 5يجهح انخىارزيً انهُذسٍح انًجهذ يُى خضٍر ػثاش (200 9) 116 25n)) انًُطقح انًرأثرج تانثهى نهؼٍُح انفىالر يُخفض انكارتىٌ تحانرها انًسرهًه ذىضح االخادٌذ وانحفر ػُذ حًم _ 10_شكم 114 -99، طفحح 4، انؼذد 5يجهح انخىارزيً انهُذسٍح انًجهذ يُى خضٍر ػثاش (200 9) 117 نؼٍُح فىالر يُخفض (20n)انًُطقح انًراثرج تانثهى نطثقح طالء انكروو انظهذ حٍث ٌالحظ ذكىٌ طثقح يٍ حطاو طثقح انطالء ػُذ حًم _ 11_شكم .(ck15)انكارتىٌ َىع ثى ذًد كرتُره ( ياٌكرو25ٌتسًك )ٌثٍٍ َرائج حٍىد االشؼح انسٍٍُح نهفىالر يُخفض انكارتىٌ انًطهً تانكروو _ 12_شكم انًظادر .5 [1] strafford k.n, “coatings and surface treatment for corrosion and wear resistance”,1st edition, ellis harwood limited, england,1984,pp.1-4,pp.62-73. [2] hyman chessin, “hard chromium plating”, metals handbook, vol.5 surface cleaning, finishing, and coating ) ,9th edition1982, pp.170-187 [3] wells t.c. “a review of surface treatments and coatings”, surfacing journal, vol.9, no.4, 1978, pp.2-9. [4] for every problem,asolutions metcor inc.560boul.arthur-sauve,saint-eustache j7r 5a8 web:www.metocor.biz. 2002. [5] www.internet ,"surface hardening of steel", seven club of great britain ,l7c home ,blatechat ,edited april 9 ,2003. [6] muna k. abbas and khairia s.hassun, "effect carburizing medium on fatigue strength for low carbon alloy steel", proceeding of the fifth jordanian international mechanical engineers association ,2-4 april ,2004. [7] ahmed s. abbas, "hard chromium electroplating and improvement the and http://www.internet/ 114 -99، طفحح 4، انؼذد 5يجهح انخىارزيً انهُذسٍح انًجهذ يُى خضٍر ػثاش (200 9) 118 metallurgy", university of technology ,baghdad ,iraq, 2002. [8] eman s. naeem, m.sc. thesis, "study of the porosity of different coating systems of low carbon steel", department of production engineering and metallurgy, university of technology ,baghdad ,iraq,1990. [9] u. n. i. d. o., “advances in material tech ", monitor vienna international center, austria, 1990, pp.9-11. [10] solov’eva z.a. and adzhiev b.u., “internal stresses of chromium coatings measured during electro deposition”, journal of surface technology, vol.23, no. 1, 1984. [11] nabil zaki, “chromium plating” products finishing directory", http://www.pfonline.com /articles / pdf 0016. htm /2000, pp.1-10. [12] iwai y. , “effects of hard chromium plating on cavitations erosion”, journal of wear, vol.128, no.2, 1988, pp.189-190. [13] thelining k.e.,“steel and its heat treatment”, 2nd edition,1984, pp.449453. [14] cameron t. b. “a perspective on the performance of carburized gear steel”, society of automotive engineers, 1985, pp.1921-1928. [15] 15halling j., "principles of tribology", published by the macmillan press limited (london), 1979, pp.94 –100, pp.105 –109. [16] mikell p. groover, “fundamentals of modern manufacturing materials processes and systems, john, wiley & sons, inc., 1999. [17] eyre t.s, "wear characteristic of metals", tribology international, 1976, pp.203-212. http://www.pfonline.com/ muna khedier abbas al-khwarizmi engineering journal, vol. 5, no. 4, pp 99-114 (2009) 119 hard chromium electroplating and improvement the properties by the thermo chemical treatments (solid carburizing) of low carbon steel muna khedier abbas amin dway thamir ahmed salloum abbas department of production engineering and metallurgy/ university of technology abstract in this research the hard chromium electroplating process, which is one of the common methods of overlay coating was used, by using chromium acid as source of chromium and sulphuric acid as catalyst since the ratio between chromic acid and sulphuric acid is (100 : 1) consequently. plating process was made by applying current of density (40 amp / dm2) and the range of solution temperature was (50 – 55oc) with different time periods (1-5 hr). a low carbon steel type (ck15) was used as substrate for hard chromium electroplating. solid carburization was carried out for hard chromium plating specimen at temperature (925oc) with time duration (2 hr) to be followed with quenching and tempering. the phase analysis was conducted by using x– ray diffraction. the examination results show that the chromium carbides in plating layer were (cr23c6, cr7c3). the microhardness of hard chromium plating specimen was measured, and the results show that the high hardness was about (907hv). after solid carburization the hardness values increase and the results show that the higher hardness for chromium plating layer on low carbon steel surface was (1276 hv). wear apparatus type (pin on disc) was used to study dry sliding wear properties of low carbon steel (as received) and hard chromium plating specimens and solid carburized. the effect of applied normal load on wear rate was studied with weighting method using five normal loads (5, 10, 15, 20, 25 n) at constant sliding speed (2.198 m / sec). the results reveal that the wear rate increases with the increasing of applied normal load. a good improvement in wear resistance was noticed for hard chromium plating specimens as compared with substrate specimen. it was also seen that, the improvement in wear resistance was (94%) as compared with substrate metal when carburizing treatment is carried out on hard chromium plating specimens. (microsoft word 45-54\332\341\355 \346\321\324\307 \346\341\314\355\344) al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 15, no. 4, december, (2019) p. p. 4554 investigation of effecting parameters in a turning operation ali abbar khleif * rasha r. elias** lujain hussein kashkul*** *,**,***department of production engineering and metallurgy/ university of technology/ baghdad/ iraq *email: 70080@uotechnology.edu.iq **email: 70166@uotechnology.edu.iq ***email: 70318@uotechnology.edu.iq (received 2 june 2019; accepted 22 august 2019) https://doi.org/10.22153/kej.2019.08.005 abstract in this study multi objective optimization is utilized to optimize a turning operation to reveal the appropriate level of process features. the goal of this work is to evaluate the optimal combination of cutting parameters like feed, spindle speed, inclination angle and workpiece material to have a best surface quality taguchi technique l9 mixed orthogonal array, has been adopted to optimize the roughness of surface. three rods of length around (200 mm) for the three metals are used for this work. each rod is divided into three parts with 50 mm length. for brass the optimum parametric mix for minimum ra is a1, b1 and c3, i.e., at tool inclination angle (5), feedrate of 0.01, spindle speed of 1200 rpm. for copper the optimal parameters combination for best ra is a1, b1 and c3, i.e., at tool inclination angle (5), feedrate of 0.01, spindle speed of 1200 rpm. for bronze the optimum parameters mix for minimum ra is a1, b1and c3, i.e., at tool inclination angle (5), feedrate of 0.01, spindle speed of 1200 rpm. keywords: taguchi technique, spindle speed, feed rate, inclination angle. 1. introduction recently, modern machining techniques face many difficulties to gain the best quality in terms of dimensional accuracy of the work piece, surface quality, low wear on cutting tools and less machining cost. surface finish of the machined part is one of the common significant criteria to evaluate the operation quality. the literature review has discovered that many attempts have been done to estimate the optimal cutting conditions in the operation of turning [1]. it is very critical part to evaluate and implement optimal machining parameters combination along with the use of suitable cutting tools. surface finish become the most important technical requirement and it is an index of product quality. the best surface quality is required for perfection of the features, strength of fatigue, resistance of corrosion and aesthetic appeal of the product [2]. the difference in the material properties and added elements is found in the material of work piece besides many factors influencing surface quality. suitable selection of cutting condition and tool can give better tool life and good surface finish. hence, a good distribution of experiments by taguchi technique for cutting conditions is employed to find their effect on surface roughness [3]. the turning is the technique of removing the access material from the outer surface of a cylindrical shaft or circular workpiece. furthermore it is used to minimize the dimensions of the work piece, often to a required dimension, and to produce a fine surface on the material. usually the work piece will be machined so that adjacent parts have many diameters. turning is the machining technique that gives cylindrical parts. it can be defined as the production of an external or internal surface: • for the rotating work piece. • for a single-point tool. ali abbar khleif al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 4554 (2019) 46 • for the feeding of tool parallel to the axis of the machined part and to remove the outer surface of the work [4]. k.mani lavanya, et al. examined the role of factors affecting the quality of surfaces machined by turning operation for the aisi-1016 steel. experiments design was set for the analysis of the effect of the turning conditions like feed rate, cutting speed and cutting depth on the surface finish. the outputs of the turning tests were used to specify the main parameters influencing surface finish by the analysis of variance technique. the most affecting parameter influencing the surface finish in the turning process was the feed rate [1]. ranganath m s, et al. studied the factors influencing the quality of surfaces machined by the turning for aluminium 6061. the process conditions taken are feed, speed and cutting depth. experiments design was conducted for the analysis of the effect of the process conditions on the surface quality by adopting taguchi technique. the outputs of the experiments were used to reveal the main elements influencing surface quality by the analysis of variance technique. the most influential process conditions on surface quality were speed and feed [3]. deepak d, rajendra b, aimed to optimize the process variables such as cutting depth, cutting velocity and feed rate on surface quality machined for the parts. analysis is performed utilizing taguchi design technique. from the results, the most significant process parameters was the feed rate which influence the surface quality, then cutting velocity and cutting depth. increasing feed rate and cutting depth will increasing the surface defects [5]. pankaj kumar sahu, et al, studied the relation between differences in hardness produced in the machined surface by turning operation depending on different machining conditions like feed, spindle speed and cutting depth have been studied. taguchi technique has been adopted to plan the experiment where the material used is aluminum. the main effects have been calculated and percentage contribution of various process parameters influencing hardness also revealed [6]. dharindom sonowal, et al. in this research the role of many cutting conditions viz. depth of cut, spindle speed and feed on surface finish of aisi 1020 mild steel bar in turning was studied and analyzed to reveal best surface quality. all the experiments are conducted on hmt lb25 lathe machine using m2 hss cutting tool. wide ranges of condition of interest have been adopted through some preliminary experiments (one factor at a time experiments). at last a combined experiment has been carried out using taguchi’s l27 orthogonal array to reveal the main influence and combination effect of all process outputs [7]. in this work three metals have been chosen as workpiece to make a comparison between them in term of surface roughness. 2. taguchi method taguchi's parametric technique is the effective technique for robust design which gives a simple and systematic qualitative optimum design to a relatively low cost. taguchi technique of off-line quality control includes all steps of product/process development. therefore, the best way for evaluating high quality at low cost is design of experiments (doe). in this research taguchi‟s technique is used to show the role of process conditions like, spindle speed, feed, tool inclination angle and workpiece material on surface quality of work material on the other hand, turning with cutting tools and getting an optimum combination of conditions may result in best surface quality [3]. 3. experimental work in this work three metals have been chosen as the specimen, zinc, copper and brass. three rods of length around (200 mm) for the three metals has been taken for this work. each rod was dividing into three parts with 50 mm length as shown below in fig. 1. the dimensions used is (∅ = 30 mm) for the specimen of the high speed steel cutting tool. in this work nine experiments are performed for each work piece utilizing turning operation for three variables. surface finishing is measured by using (marsurf ps1) device for 27 experiments for the three workpieces. the parameters and their levels are listed in the table 1. the distribution of the experiments and the machining parameters are shown in the table 2. fig. 1. the work pieces after machining. ali abbar khleif al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 4554 (2019) 47 table 1, machining variables and their levels code cutting parameter levels 1 2 3 a tool inclination angle (degree) 5 0 -5 b feedrate (mm/ min) 0.01 0.04 0.08 c spindle speed (rpm) 540 800 1200 table 2, the distribution of the experiments and the parameters. 4. results and discussion table 3 explains the experimental readings of machining brass alloy depending on l9 orthogonal array. the surface roughness (ra) in µm has been measured. the mean of these features and signal to noise (s/n) ratio (in decibels) are shown for the output of the process in the tables 4 and 5. also figs. 2 and 3 show the affected plot of the factors versus means and s/n ratio. 4.1. estimation of optimum parameters for roughness (ra) for brass figs. 2 and 3 illustrate the plot of machining variables versus the response (surface roughness) for mean and s/n ratio. as explained in table 3 of the results of means, all the three used conditions of tool inclination angle (a), feedrate (b) and spindle speed (c) practically affect the mean of the (ra) values. it can be noticed that the optimum parametric mix for minimum ra is a1, b1 and c3, i.e., at tool inclination angle (5), feedrate of 0.01, spindle speed of 1200 rpm. it is found that the parameters combination within the proposed range as detailed previously produced lowest surface roughness of brass alloy. using these data the optimum surface roughness can be predicted according to the relation: predicted mean (ra) = a1+b1+c3–2*(average mean) [1] where: a1= average of (ra) at the first level of tool inclination angle. b1= average of (ra) at the first level of feedrate c3= average of (ra) at the third level of spindle speed. from table 4 the predicted mean (ra) equal to = 2.525+3.873+3.567-2*4.191 = 1.583 µm ex. no. coded values real values a b c angle (degree) feedrate (mm/ min) spindle (rpm) 1 1 1 1 5 0.01 540 2 1 2 2 5 0.04 800 3 1 3 3 5 0.08 1200 4 2 1 2 0 0.01 800 5 2 2 3 0 0.04 1200 6 2 3 1 0 0.08 540 7 3 1 3 -5 0.01 1200 8 3 2 1 -5 0.04 540 9 3 3 2 -5 0.08 800 ali abbar khleif al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 4554 (2019) 48 table 3, results for brass. exp. no. coded values real values measurements a b c angle (degree) feedrate (mm/min) spindle (rpm) ra1 ra2 ra3 means s/n 1 1 1 1 5 0.01 540 2.533 2.584 2.539 2.552 8.138 2 1 2 2 5 0.04 800 2.430 2.210 2.480 2.373 -7.518 3 1 3 3 5 0.08 1200 2.650 2.680 2.620 2.650 -8.465 4 2 1 2 0 0.01 800 4.754 4.853 4.844 4.817 -13.655 5 2 2 3 0 0.04 1200 3.700 3.900 3.800 3.800 -11.597 6 2 3 1 0 0.08 540 4.950 4.910 4.980 4.946 -13.886 7 3 1 3 -5 0.01 1200 4.220 4.280 4.250 4.250 -12.567 8 3 2 1 -5 0.04 540 5.422 5.437 5.485 5.448 -14.724 9 3 3 2 -5 0.08 800 6.870 6.900 6.880 6.883 -16.756 table 4, response table for means for brass. level angle (degree) feed (mm/ min) spindle (rpm) 1 2.525 3.873 4.316 2 4.521 3.874 4.691 3 5.527 4.827 3.567 delta 3.002 0.954 1.125 rank 1 3 2 table 5, response table for signal to noise ratios for brass. level angle (degree) feed (mm/min) spindle (rpm) 1 -8.040 -11.454 -12.250 2 -13.047 -11.280 -12.643 3 -14.683 -13.036 -10.877 delta 6.643 1.756 1.766 rank 1 3 2 50-5 5 4 3 0.080.040.01 1200800540 5 4 3 angle(degree) m e a n o f m e a n s feed(mm/ min) spindle (rpm) main effects plot for means data means fig. 2. plot for means for brass. ali abbar khleif al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 4554 (2019) 49 50-5 -8 -10 -12 -14 0.080.040.01 1200800540 -8 -10 -12 -14 angle(degree) m e a n o f s n r a t io s feed(mm/ min) spindle (rpm) main effects plot for sn ratios data means signal-to-noise: smaller is better fig. 3. plot for signal to noise for brass. table 6 represents the experimental results of machining copper alloy depending on taguchi l9 mixed array. the output characteristic, ra in µm has been measured and evaluated. the average (mean) of this feature and s/n ratio (in decibels) are shown for each feature in the tables 7 and 8. also figs. 4 and 5 show the effect plot of the factors versus means and s/n ratio. 4.2 estimation of optimum parameters for roughness (ra) for copper figs 4 and 5 show the plot of machining variables versus the response (surface roughness) for mean and s/n ratio. as seen in table 7 which shows the results of means, all the machining parameters of tool inclination angle (a), feedrate (b) and spindle speed (c) significantly influence both the mean and the variation in the (ra) values. it can be noticed that the optimal parameters combination for best ra is a1, b1 and c3, i.e., at tool inclination angle (5), feedrate of 0.01, spindle speed of 1200 rpm. it is proposed that the parameters combination within the specified range as mentioned above gives minimum surface defects ra for finishing of brass alloy. using these data the optimum surface roughness can be predicted according to the relation: predicted mean (ra) = a1+b1+c3–2*(average mean) where: a1= average of (ra) at the first level of tool inclination angle. b1= average of (ra) at the first level of feedrate. c3= average of (ra) at the third level of spindle speed. from table 4 the predicted mean (ra) = 2.261+2.563+2.605 2*5.978 =1.451 µm table 6, results for copper. ex. no coded values measurements a b c ra1 ra2 ra3 means s/n 1 1 1 1 2.38 2.48 2.38 2.38 -7.55 2 1 2 2 1.82 1.85 1.864 1.84 -5.32 3 1 3 3 2.41 2.51 2.719 2.55 -8.14 4 2 1 2 2.69 2.59 2.634 2.64 -8.43 5 2 2 3 2.45 2.85 2.487 2.59 -8.31 6 2 3 1 4.26 4.46 4.220 4.31 -12.69 7 3 1 3 2.58 2.63 2.780 2.66 -8.51 8 3 2 1 3.34 3.35 3.412 3.36 -10.54 9 3 3 2 4.55 4.65 4.398 4.35 -13.13 ali abbar khleif al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 4554 (2019) 50 table 7, response table for means. level angle (degree) feed (mm/min) spindle (rpm) 1 2.261 2.563 3.355 2 3.185 2.605 3.008 3 3.522 3.800 2.605 delta 1.262 1.237 0.750 rank 1 2 3 table 8, response table for signal to noise ratios smaller is better. level angle (degre) feed (mm/min) spindle (rpm) 1 -10.732 -8.168 -10.267 2 -9.819 -8.065 -8.966 3 -7.008 -11.327 -8.327 delta 3.724 3.263 1.939 rank 1 2 3 50-5 4.0 3.5 3.0 2.5 0.080.040.01 1200800540 4.0 3.5 3.0 2.5 angle m e a n o f m e a n s feed rpm main effects plot for means data means fig. 4. plot for means for copper. 50-5 -7 -8 -9 -10 -11 0.080.040.01 1200800540 -7 -8 -9 -10 -11 angle m e a n o f s n r a t io s feed rpm main effects plot for sn ratios data means signal-to-noise: smaller is better fig. 5. plot for signal to noise for copper. ali abbar khleif al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 4554 (2019) 51 table 9 represents the measured results of machining copper alloy depending on taguchi l9 mixed array. the average and s/n ratio (in decibels) are shown for each feature in the tables 10 and 11. also figs. 6 and 7 show the plot of the parameters versus means and s/n ratio. 4.3 estimation of optimum parameters for roughness (ra) for bronze and to figures (6) and (7) show the plot of machining factors versus the response (surface roughness) for mean and s/n ratio. as seen in table (7) the results of means, all the selected input parameters of tool inclination angle (a), feedrate (b) and spindle speed (c) mainly influenced both the mean and the difference in the (ra) values. it can be noticed that the optimum parameters mix for minimum ra is a1, b1and c3, i.e., at tool inclination angle (5), feedrate of 0.01, spindle speed of 1200 rpm. it is clear that the parameters combination within the specified range as mentioned above produce best surface quality ra for finishing of brass alloy. using these data the optimum surface roughness can be predicted according to the relation: predicted mean (ra) = a1 +b1 +c3– 2*(average mean) a1= average of (ra) at the first level of tool inclination angle. b1= average of (ra) at the first level of feedrate. c3= average of (ra) at the third level of spindle speed. from table 4 predicted mean (ra) = 2.519+3.370+3.525 2*3.796 =1.822 µm table 9, results for bronze. ex. no. coded values measurements a b c ra1 ra2 ra3 mean s/n 1 1 1 1 2.35 2.45 2.37 2.39 -7.57 2 1 2 2 1.53 1.54 1.56 1.54 -3.78 3 1 3 3 3.57 3.61 3.68 3.62 -11.17 4 2 1 2 4.32 4.73 4.87 4.64 -13.34 5 2 2 3 3.76 3.88 3.98 3.87 -11.77 6 2 3 1 4.69 4.97 4.94 4.86 -13.75 7 3 1 3 3.03 3.17 3.02 3.07 -9.76 8 3 2 1 5.05 4.86 4.95 4.95 -13.90 9 3 3 2 5.25 5.18 5.12 5.18 -14.2 table 10, response table for means for bronze. level angle (degree) feed (mm/min) spindle (rpm) 1 2.519 3.370 4.073 2 4.464 3.460 3.792 3 4.407 4.559 3.525 delta 1.944 1.189 0.548 rank 1 2 3 table 11, table for signal to noise ratios for bronze smaller is better. level angle(degree) feed(mm/min) spindle(rpm) 1 -12.656 -10.228 -11.744 2 -12.958 -9.820 -10.477 3 -7.510 -13.076 -10.904 delta 5.448 3.256 1.267 rank 1 2 3 ali abbar khleif al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 4554 (2019) 52 50-5 4.5 4.0 3.5 3.0 2.5 0.080.040.01 1200800540 4.5 4.0 3.5 3.0 2.5 angle m e a n o f m e a n s feed rpm main effects plot for means data means fig. 6. plot for means for bronze. 50-5 -8 -10 -12 0.080.040.01 1200800540 -8 -10 -12 angle m e a n o f s n r a t io s feed rpm main effects plot for sn ratios data means signal-to-noise: smaller is better fig. 7. plot for signal to noise for bronze. 5. conclusions the most important results revealed from the present work are listed as in the following: 1the optimal parametric combination of machining factors for minimum surface roughness (ra) for brass, copper and bronze are a1 b1 c3, i.e., at (5) tool inclination angle, feedrate of 0.01 and spindle speed of 1200 rpm. tool inclination angle has the highest effect then spindle speed and then feed rate on roughness (ra) as seen from the rank of the effect of parameters. 2from the calculated predicted values of the surface roughness for the three metals the minimum surface roughness is found in copper because of the ductility of the copper. 3it has been found that taguchi technique is good tool for predicting the process outputs. 6. references [1] k.mani lavanya, r. k. suresh,a.sushil kumar priya and v. diwakar reddy, "optimization of process parameters in turning operation of aisi-1016 alloy steels ali abbar khleif al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 4554 (2019) 53 with cbn using taguchi method and anova", iosr journal of mechanical and civil engineering (iosr-jmce), vol.7, pp. 2427, (2013). [2] ranganath m s, vipin and harshit, "optimization of process parameters in turning operation using response surface methodology", international journal on emerging technologies and advanced engineering, vol.4, issue 10, (2014). [3] ranganath m s, vipin and r. s. mishra, "optimization of process parameters in turning operation of aluminium (6061) with cemented carbide inserts using taguchi method and anova", international journal of advance research and innovation, vol.1, issue 1, (2013). [4] p. p. shirpurkar, s.r. bobde, v.v.patil and b.n. kale, "optimization of turning process parameters by using tool insertsa review", international journal of engineering and innovative technology (ijeit) volume 2, issue 6, (2012). [5] deepak d,rajendra b, "optimization of machining parameters for turning of al6061 using robust design principle to minimize the surface roughness", international conference on emerging trends in engineering, science and technology (icetest2015). [6] pankaj kumar sahu, novel kumar sahu, ankit dubey, "optimization of cutting parameters by turning operation in lathe machine", international journal of mechanical and production engineering, vol 5, issue 11, (2017). [7] dharindom sonowal, dhrupad sarma, parimal bakul barua andthuleswar nath,"taguchi optimization of cutting parameters in turning aisi 1020 ms with m2 hss tool", iop conference series: materials science and engineering 225, (2017). )2019( 4554، صفحة ٤د، العد15دالهندسية المجلجلة الخوارزمي معلي عبار خليف 54 دراسة العوامل المؤثرة في عملية الخراطة ***لجين حسين كشكول **رشا رامز الياس *علي عبار خليف الجامعة التكنولوجية /قسم هندسة االنتاج والمعادن **،****، uotechnology.edu.iq@70080 *البريد االلكتروني: uotechnology.edu.iq@70166 **البريد االلكتروني: uotechnology.edu.iq@70318***البريد االلكتروني: الخالصة تم تبني االمثلية متعددة االهداف لتحقيق االمثلية لعملية الخراطة و اكتشاف الظروف المالئمة لخواص العملية. ان الهدف من هذا البحث في هذه الدراسة تبني ي. تمهو ايجاد افضل مجموعة عوامل قطع مثل التغذية، سرعة الدوران، زاوية ميالن الحد القاطع و معدن المشغولة اليجاد افضل نوعية انهاء سطح دن تم استخدامها في هذا البحث. كل عمود مقسم الى ثالثة املم لثالثة مع ٢٠٠اليجاد افضل انهاء سطحي. ثالثة قضبان بطول 9l تقنية تاكوجي بمصفوفة ) ٥ميالن عدة ( اي عند زاوية 3c و b1a,1 عوامل تعطي اقل خشونة سطحية بالنسبة لمعدن البراص كانتالملم. و قد وجد ان افضل ٥٠اقسام بطول درجة و ٥اي زاوية ميالن c1,b1a,3 دورة بالدقيقة . أما بالنسبة للنحاس فكانت افضل ظروف هي ١٢٠٠و سرعة دوران ٠٫٠١درجة و معدل تغذية درجة و معدل ٥يالن اي زاوية م c1,b1a,3 دورة بالدقيقة. كذلك بالنسبة لمعدن البرونز فان الظروف كانت ١٢٠٠و سرعة دوران ٠٫٠١معدل تغذية .دورة بالدقيقة ١٢٠٠و سرعة دوران ٠٫٠١تغذية this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 20, no. 4, december (2024), pp. 89-98 enhancing the surface mechanical properties of al2618 alloy 3o2sing a pld device with aiu sturbocharger sarah s. faraj1, nabil h. hadi2* department of mechanical engineering, university of baghdad, baghdad, iraq 1 departments of aeronautical engineering, university of baghdad, baghdad, iraq 2 *corresponding author, s email: dr.nabil.hassan@coeng.uobaghdad.edu.iq (received 29 april 2024; revised 18 june 2024; accepted 28 july 2024; published 1 december 2024) https://doi.org/10.22153/kej.2024.07.004 abstract pulsed laser deposition (pld) has become a widely used technology for fabricating multicomponent thin films. in this research, nanomaterial alfa-al2o3 with a particle size of 30 ± 5 nm was deposited on the surface of al-2618 alloy turbine blades. the microstructure, phase composition and the effects of a coating made from alfa-al2o3 nanomaterial were studied. pld was employed to improve the mechanical performance of the aluminium alloy (al-2618) used in turbocharger blades, primarily to reduce corrosion and erosion. to ensure high hardness and extended fatigue life, a 10 μm layer of aluminium dioxide was deposited on the surface of the aluminium alloy using pld. the mechanical properties of the blade improved, as shown by hardness tests conducted on the samples. an energy-dispersive x-ray spectroscopy test was conducted before and after deposition. after depositing a nanolayer of al2o3, the mechanical properties were enhanced. the hardness of the samples increased from 685 hld to 781 hld, and corrosion and erosion were reduced. the atomic percentage of oxygen deposited on the blade surface ranged from 0.6% to 0.8%, and the surface roughness (x) decreased from 49.5 µm to 22.8 µm because of the nanolayer applied via pld. keywords: turbocharger blade; surface improvement; nanomaterial (alfaal2o3), corrosion; erosion; pld 1. introduction since the early 20th century, precipitates have been used to reinforce various alloys. in recent decades, extensive research has focused on alloys with nanostructured (ns) or ultrafine-grain (ufg) structures, both of which share the challenge of poor ductility [1]. the precipitation behaviour in ns or ufg alloys differs from that in their conventional coarse-grained counterparts. however, adding precipitates has been proven to be a viable technique for resolving the strength–ductility tradeoff. a review of precipitation’s scientific discovery in the last 20 years in ns or ufg alloys is presented in this article. the study covered the growth and formation mechanism of precipitates, their interactions with dislocations, grain boundaries or solid solutes and the resulting mechanical behaviour [1]. pulsed laser deposition (pld) is the most common physical method for thin films, obtaining a coating with qualitative specifications and inappropriate vacuum media. when an electrical discharge occurs between two electrodes under relatively low pressure, a beam with high-energy ions is generated to extract atoms from the surfaces of the targets when they collide [2]. the growing need for robust, lightweight materials has led to the development of numerous families of age-hardenable aluminium alloys. precise control over the formation of alloy microstructures during solidification and subsequent thermomechanical processing is essential for producing high-quality, reliable cast and wrought products. the development of an equiaxed, fine-grained structure in castings has long mailto:dr.nabil.hassan@coeng.uobaghdad.edu.iq https://doi.org/10.22153/kej.2024.07.004 https://doi.org/10.22153/kej.2024.07.004 sarah s. faraj1 al-khwarizmi engineering journal, vol. 20, no.4, p.p. 8998 (2024) 90 been known to improve mechanical properties, reduce hot tearing and boost feeding to eliminate shrinkage porosity, resulting in a more uniform, finer distribution of second phases [3]. a thin film is a layer deposited onto a substrate with the objective of improving the physical properties of the surface for specific applications. multiple layers, such as double, triple or quadruple, can be deposited simultaneously in a single layer [4]. several methods are used to create thin films, one of which is plasma deposition, performed at low temperatures. operating at low temperatures activates chemical reactions. aluminium and its alloys are critical in various industries due to their excellent physical properties, high strength-toweight ratio, strong corrosion resistance, ease of processing and forming, non-toxicity and recyclability [5, 6]. the al-cu-mg-fe-ni forging alloy, known as aluminium alloy 2618, was developed for use in aerospace engine components and automotive applications. its excellent hightemperature strength, reaching up to 238 °c, is achieve a combination of precipitation and dispersion hardening [7-11]. corrosion is a modern dilemma, as the damage it causes to tools and equipment leads to substantial material and financial losses. corrosion occurs in various forms and can be categorised into two main types: wet corrosion and dry corrosion. wet corrosion is a corrosion process in which the liquid phase plays a key role, either through direct interaction or by serving as a medium for the reaction. on the contrary, dry corrosion involves the direct interaction between gas or vapour and the corroded material, without the presence of a liquid phase. corrosion can be defined as the chemical interaction between a material and the surrounding atmosphere in direct contact with it, whether the atmosphere is air or any other chemical environment [12-14]. this study enhances the mechanical properties of turbocharger surfaces by depositing a thin film of aluminium dioxide (al2o3) onto samples manufactured from aluminium alloy (al2618). the coated samples were then tested for use in the manufacturing of turbocharger blades to achieve a protective layer with high efficiency, increased hardness and enhances corrosion resistance. 1.1 pulsed laser deposition device pld has gained popularity in the production of multi-component thin films. high-temperature superconductors, compound semiconductors, dielectrics, ferroelectrics, gigantic magnetoresistance and electro-optic oxides, polymers and diverse heterostructure types have been extensively researched [15] by heidelberg (1996) with a third edition scheduled for release in 2000. large grain orientation and epitaxial films are produced by ablating the target material at pressures below 0.1 mb, either in an inert, reactive environment or in a vacuum. the primary mechanism for film formation involves the flow of atoms and ions interacting with molecules on the substrate surface. assuming the creation of smallarea films, measuring several square millimetres, pld is a fast, simple and highly reliable process for experimentation. thin films can be produced using a variety of materials without the need for hazardous or corrosive processes. the quick turnaround times enable the thorough examination of a wide range of chemicals and film doping variations. these factors make pld especially appropriate for materials research and development. the target material is ablated at pressures of approximately 0:01 to produce epitaxial and large-grain-oriented films, either in inert or reactive atmospheres, or in a vacuum. in this process, small molecules and atoms/ions striking the substrate surface are the main sources of flux used to synthesise the films. the situation changes remarkably from one to several hundred mb. these circumstances encourage vapour-phase condensation and the formation of clusters and nanocrystals. these nanocrystals contain 102–106 atoms, with sizes ranging from 1–20 nm [16]. 1.2 alfaal2o3 layers alpha alumina (α-al2o3) content determination is one of the primary applications of x-ray diffraction (xrd) analysis. however, notable variations are observed in the relative intensities of the principal xrd reflections depending on the morphological shapes of rhombohedral alumina due to the preferred orientation effect). moreover, the x-ray diffraction power of a specimen may vary, complicating or eliminating the use of a reference material. as a result, comparing the intensities of certain reflections from a sample to those of a reference material can lead remarkable analytical errors. using conventional xrd coupled with the rietveld approach, the concentrations of alpha and beta alumina (β-al2o3=na2o•11al2o3) were investigated in nine commercial ceramic alumina, three nist standards and two unique grades of alumina. the morphology of the materials were also assessed using scanning electron microscopy (sem) [17]. sarah s. faraj1 al-khwarizmi engineering journal, vol. 20, no.4, p.p. 8998 (2024) 91 2. experimental work this experiment was conducted under the following conditions: pressure of 3.3 *10−2 bar, energy of 1520 mj, frequency of 10 hz and 500 impulses, as shown in figure 1. after completing the deposition process, the turbine blade was examined at the industrial research and development center, where the properties of the blade were improved using the pld device. a nanomaterial (alfaal2o3) with a particle size of 30 ± 5 nm was deposited on the surface of the turbine blade (al-2618). the device setup technical parameters are as follows: wavelengths of 532, 1064 and 1320 nm; pulse width of 10 ns; energy of 20— 2000 mj; working frequency of 1–10 hz; spot diameter of 1–8 mm; cooling method of water cooling + air cooling; total power of 300 w. the force applied by the al2o3 particles to slow down recrystallisation can be expressed as follows [18]: pz = 3fγ/2r. (1) the average size of the particles (al2o3) is r = (30 ± 5) * (10−7) m, the volume fraction is f = 0.83%, and the boundary energy is γ = 53.75 j/m2. according to the computation, the force pz exerted by the al2o3 particles is 15.6 mpa. recrystallisation is prevented more effectively in 2618-(al2o3) than in aa2618 because more al2o3 particles exist in the latter. similarly, the grain boundary velocity in 2618-(al2o3) is lower than in aa2618 for the same reason (pz = 22.30 mn). fig. 1. pulsed laser deposition device 3. results and discussion 3.1 edx test energy-dispersive x-ray spectroscopy (edx) examination is the first step in material analysis. the distinctive pattern of the absorption bands indicates an improvement in the material composition as the chemical composition of small particles changes. the results showed an increase in compressive strength, enhanced ductility and higher hardness after depositing a layer of al2o3 on the composite material using glow discharge plasma, as shown in figure 2. a. before deposition without filter b. after deposition without filter c. before deposition with filter d. after deposition with filter sarah s. faraj1 al-khwarizmi engineering journal, vol. 20, no.4, p.p. 8998 (2024) 9 fig. 2. (edx) examination for turbocharger blades the atomic and weight percentages of oxygen (o) increased because of the deposition, whereas those of aluminium (al) decreased. tables 1–2 show the atomic and weight percentages for elements o and al before and after deposition. table 1 (edx) examination for turbocharger blades before deposition table 2 (edx) examination for turbocharger blades after deposition 3.2 hardness test when determining a material’s hardness, the brinell and rockwell procedures require considerable force and create a broad surface impression. although optical measurement is incorporated into the vickers hardness testing method, it is unsuitable for permanently assembled components or machinery that has been installed. leeb hardness testing instruments use indirect and rebound techniques to quantify hardness. however, notable differences are found when converting leeb hardness values to brinell, rockwell and vickers hardness scales. ultrasonic hardness testers, on the contrary, leave a small imprint on the surface of the material and quantify hardness using the highaccuracy ultrasonic contact impedance (uci) method. nonetheless, an ultrasonic hardness tester tends to be more expensive due to its high level of precision and nearly nondestructive nature of the assessment it provides [19]. the technical details are as follows: measurement range of 170–960 hld; measurement direction of 0°–360°; hardness scale of hl, hb, hrb, hrc, hra, hv and hs. figure 3 shows that the maximum load values are 500 n, 50 kg, 110 lb and 1800 oz; the load division values are 0.1 n, 0.01 kg, 0.01 lb and 1o z; the accuracy is ±1％. the results of the hardness test for turbocharger blades before and after deposition are displayed in table 3 and figure 4. fig. 3. hardness tester element atomic % atomic % error weight % weight % error o 3.6 0.6 2.2 0.3 al 96.4 0.3 97.8 0.3 element atomic % atomic % error weight % weight % error o 13.8 0.8 8.7 0.5 al 86.2 0.3 91.3 0.3 sarah s. faraj1 al-khwarizmi engineering journal, vol. 20, no.4, p.p. 8998 (2024) 93 table 3, hardness test for turbocharger blades. sample number. before deposition (hld) after deposition (hld) 1 685 781 (a) before deposition (hld) (b) after deposition (hld) fig. 4. hardness tester for turbocharger blades 3.3 surface topography using afm test atomic force microscopy (afm), also known as scanning probe microscopy, provides near-atomic resolution images for measurement. afm can measure surface roughness down to the angstrom scale. in addition to surface images, afm analysis can offer quantitative estimates of feature sizes, such as step heights and other dimensions. the distinctive pattern of absorption bands indicates an improvement. figures 5–8 illustrate the decline in the value of x from 49.5 µm to 22.8 µm. moreover, qualitative mapping of additional physical characteristics, such as adhesion, modulus, dopant distribution, conductivity, surface potential, electric field and magnetic domains, may be achieved using sophisticated afm measurement modes. sarah s. faraj1 al-khwarizmi engineering journal, vol. 20, no.4, p.p. 8998 (2024) 94 a2d b3d fig. 5. afm tester for turbocharger blades before deposition. fig. 6. afm tester parameters for turbocharger blades before deposition. sarah s. faraj1 al-khwarizmi engineering journal, vol. 20, no.4, p.p. 8998 (2024) 95 a2d b-3d fig. 7. afm tester for turbocharger blades after deposition. fig. 8. afm tester parameters for turbocharger blades before deposition sarah s. faraj1 al-khwarizmi engineering journal, vol. 20, no.4, p.p. 8998 (2024) 96 4. conclusions 1. the mechanical properties of a turbocharger blade made of aluminium alloy (al-2618) and coated with al2o3 are explored in this work. 2. a nanolayer of al2o3 was deposited using a pld device, and the samples were examined after deposition using an edx device, hardness tester and afm. 3. the atomic percentage of oxygen deposited on the surface of the turbocharger blade ranges from 0.6% to 0.8%. 4. the hardness of the samples increased from 685 hld to 781 hld. 5. after deposition, the roughness asperities x decreased in height from 49.5 µm to 22.8 µm due to the nanolayer deposited using a pld device. references [1] kaka ma, yufeng zheng, sriswaroop dasari, dalong zhang, hamish l. fraser & rajarshi banerjee ,” precipitation in nanostructured alloys: a brief review”, volume 46, pages 250–257, (2021). [2] v. i. arkhipenko, s, m, zgirouski, a. a. kirillov, and l. v. simonchik, plasma physics reports, 28, 930 (2002). [3] kun yu, wenxian li, songrui li, jun zhao,” mechanical properties and microstructure of aluminum alloy 2618 with al3(sc, zr) phases”, materials science and engineering: a,volume 368, issues 1–2, 15 march 2004, pages 88-93. [4] p.malekzadeh,"a differential quadrature nonlinear free vibration analysis of laminated composite skew thin plates", journal of thin wall structures ,vol.(45),pp.237-250,january 2007. [5] j.e. samad, j.a. nychka, wettability of biomimetic thermally grown aluminum oxide coatings, bioinsp. biomim. 6 (2011) 016004– 016009. [6] j.f. joanny, polyelectrolyte adsorption and charge inversion, eur. phys. j. b 9,(1999). [7] i. n. a. oguocha, s. yannacopoulos and y. jin, the structure of aixfeni phase in al-cumg-fe-ni, j. mater. sci., vol. 31 (1996), 5615–5621. [8] j. h. wang, d. q. yi and x. p. su, et al., influence of deformation ageing treatment on microstructure and properties of aluminum alloy 2618, mater. charact. vol. 59 (2008), 965–968. [9] z. w. du, g. j. wang and x. l. han, et al., microstructural evolution after creep in aluminum alloy 2618, j. mater. sci., vol. 47 (2012), 2541–2547 [10] akeel dhahir subhi and adnan mohsen abd,” improving wear properties of 392 al alloy using centrifugal casting”, department of production engineering and metallurgy / university of technology/ baghdad, vol. 15 no. 1 (2019): alkhwarizmi engineering journal [11] alalkawi h. j. m., ali yousuf k khenyab andabduljabar h. ali,” improvement of mechanical and fatigue properties for aluminum alloy 7049 by using nano composites technique”, department of electromechanical engineering/ university of technology/ baghdad/ iraq, doi: https://doi.org/10.22153/kej.2019.08.001, vol. 15 no. 1 (2019): al-khwarizmi engineering journal. [12] n. mathan kumar a, s. senthil kumaran b, l.a. kumaraswamidhas a,” an investigation of mechanical properties and corrosion resistance of al2618 alloy reinforced with si3n4, aln and zrb2 composites”, journal of alloys and compounds volume 652, 15 december 2015, pages 244-249. [13] saad abdel wahed tohme1, hana khaled khalaf, nour ali nasser, ahmed dawoud salman,”manufacturing of aluminum alloy reinforced polymer and the possibility of using it in a solar heater”, industrial research and development authority renewable energy and environment research center. [14] aseel basim abdul-hussein, fadhel abbas hashim and tamara raad kadhim,” effect of nano powder on mechanical and physical properties of glass fiber reinforced epoxy composite”,department of materials https://doi.org/10.22153/kej.2019.08.001 sarah s. faraj1 al-khwarizmi engineering journal, vol. 20, no.4, p.p. 8998 (2024) 97 engineering/ university of technology, vol. 12 no. 3 (2016): 2016. [15] d. bäuerle: laser processing and chemistry, 2nd ed. (springer, berlin). [16] w. marine, b. luk'yanchuk, m. sentis: le vide science, technique et applications, 2=4, 440 (1998). [17] frank feret,daniel roy and clermont boulanger,” determination of alpha and beta alumina in ceramic alumina by x-ray diffraction”, july 2000,spectrochimica act part b atomic spectroscopy 55(7):10511061. [18] j.h. wang and d.q. yi ,”preparation and properties of alloy 2618 reinforced by submicron aln particles”, (submitted february 15, 2005; in revised form november 17, 2005). [19] ifeyinwa obianyo,”laboratory manual for hardness test”, nile university of nigeria, abuja ,march 2019. (2024) 89-89، صفحة 4، العدد20مجلة الخوارزمي الهندسية المجلد سارة سعد فرج 98 al2618 تحسين الخواص الميكانيكية لسطح الشاحن التوربيني المصنع من سبيكة ai2o3مع pld باستخدام جهاز *2هاديحسن نبيل ،1فرج سعدسارة بغداد، بغداد، العراققسم الهندسة الميكانيكية، جامعة 1 أقسام هندسة الطيران، جامعة بغداد، بغداد، العراق2 dr.nabil.hassan@coeng.uobaghdad.edu.iq: البريد االلكتروني* المستخلص في هذا البحث دراسة مرحلة البنية المجهرية تم .المعادن باألغشية الرقيقة لطالء سطحتقنية واسعة االنتشار (pld) ترسيب الليزر النبضي ، وانجز الترسيب بجهاز الليزر النبضي لتحسين األداء الميكانيكي لشفرات الشاحن (alfaal2o3) وتركيب وتأثير الطالء المصنع من مادة نانوية شفرات الشاحن تقليل التآكل بالكالل والتآكل الكيمياوي ل، من مميزات استخدام التقنية (al-2618) التوربيني المصنعه من سبائك األلومنيوم من ثاني أكسيد 10μm) طبقة بسمك) يتم ترسيبالليزر النبضي بواسطه جهاز الترسيبطويل األمد، ال عمرالتوربيني ، ولضمان الصالبة العالية وال سطح الخواص الميكانيكية ل نالحظ تحسن،بعد اجراء الفحصوصات المختبريه .الشاحن التوربينيشفرات على سطح ( al2o3األلومنيوم النانوي ) قد وجد أنه بعد ترسيب طبقة النانويةو .قبل وبعد عملية الترسيب (edx) ( وafm) اختباروصالبة ال اجراء اختبارحيث تم احن التوربيني.شال .زادت الصالبة وقل التآكل، (al2o3) من ثاني أكسيد األلومنيوم mailto:dr.nabil.hassan@coeng.uobaghdad.edu.iq فورمات المجلة this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 20, no. 2, june, (2024), p p. 3955 a review on tool pin geometry of friction stir welding walaa h. ahmed*, ali h. kadhum** and mohd shukor salleh*** *,** department of automated manufacturing, al-khwarizmi college of engineering, university of baghdad, iraq ***department of manufacturing engineering, faculty of industrial and manufacturing technology and engineering,universiti teknikal malaysia melak, melaka, malaysia corresponding author: *e-mail: walaa.abbas1604@kecbu.uobaghdad.edu.iq ** email: kadhumali59@yahoo.com ***email: shukor@utem.edu.my (received 30 august 2023; accepted 18 february 2024; published 1 june 2024) https://doi.org/10.22153/kej.2024.02.001 abstract friction stir welding (fsw) is an innovative solid joining operation that has recently been intensively adopted in welding various similar and dissimilar metallic materials, including aluminum, steel, titanium alloys, and others. the success of fsw relies on a set of parameters like rotational speed, travel speed, axial force, tool geometry, etc. the role of tool geometry (involving both pin and shoulder design) is highly important in producing sound and high-strength weld joints. therefore, this research aims to review the latest published works regarding the performance of different tool geometries. the discussion of the findings of the cited works revealed that each tool pin design has shown different behavior due to the various stirring efficiencies of the materials being welded. all in all, the square threaded pin had the best geometry in terms of its mechanical properties compared to other pin designs. the threaded cylinders and threaded taper are most commonly utilized and offer good joints, while the maximum joint efficiency was achieved by the square pin profile and it reached 94% in some investigations. keywords: tool pin geometry; friction stir welding fsw; fsw parameters 1. introduction friction stir welding (fsw) has become a relatively new welding method that was developed by wayne thomas in 1991 at the welding institute (twi) of the united kingdom as a solid-state welding technique[1-4]. this innovation is a huge success for joining materials with low melting temperatures and aluminum alloys [5-7]. recently, fsw is a versatile joining process capable of welding a wide range of metallic alloys. some of the metallic alloys commonly welded using fsw include: aluminum, magnesium, steel, titanium, and so on. each alloy has its own set of properties, and fsw parameters need to be carefully adjusted to suit the material being welded. the process parameters, tool design, and optimization methods may vary depending on the alloy being joined to achieve high-quality welds with desirable mechanical properties. ongoing research continues to expand the range of alloys weldable through fsw and improve the quality of joints in different materials. figure 1 shows the diagram of the fsw process. the shipping, aerospace, automotive, rail, and construction industries are among the industries that use fsw. these days, fsw is being progressively introduced to the at sea structure and energy sectors. [8-10], fsw is also highly advantageous in terms of economic and environmental considerations [1113]. mailto:walaa.abbas1604@kecbu.uobaghdad.edu.iq mailto:kadhumali59@yahoo.com mailto:shukor@utem.edu.my mailto:shukor@utem.edu.my https://doi.org/10.22153/kej.2024.02.00 walaa h. ahmed al-khwarizmi engineering journal, vol. 20, no.2, p.p. 3955(2024) 40 fig. 1. basic principle of the fsw process [14]. in fsw, primary and secondary parameters are the two groups of factors that affect the quality of the weld joint. the traverse speed, rotational speed, and tool geometry are the main parameters. in the meantime, the pin profile, welding tool material, workpiece thickness, and workpiece material are the secondary parameters [15-16]. the performance of the fsw process is assessed and judged based on various parameters that determine the quality of the weld and the efficiency of the process. some key parameters that are used to evaluate the performance of fsw include [17]: 1.weld quality evaluation: assessing weld effectiveness involves scrutinizing for defects like voids, cracks, and incomplete fusion, alongside ensuring adequate joint strength. 2.mechanical properties: key characteristics include toughness, ductility, fatigue resistance, and tensile strength, pivotal for assessing the weld's performance. 3.microstructural analysis: evaluating alterations in the microstructure across the base material, heataffected zone (haz), and weld area is crucial for understanding material behavior post-welding. 4.efficiency metrics: process efficiency encompasses factors like repeatability, energy consumption, tool longevity, and welding speed, impacting the overall effectiveness of friction stir welding (fsw). 5.process variables: optimizing parameters such as tool geometry, axial force, rotational speed, and feed rate directly influences weld quality and consistency. 6.heat-affected zone characteristics: understanding haz features, including shape, composition, thermal distortion, and metallurgical changes, aids in comprehending the weld's surrounding environment. ongoing research and development endeavors aim to enhance fsw performance by evaluating and refining the process for diverse materials and applications using these indices and parameters. by broadening its utilization across a wider spectrum of materials and industrial needs, and by improving both weld quality and process efficiency, the aim is to elevate the effectiveness of the fsw process [18]. 2. the importance of tool geometry and its role in succeeding the fsw weld joints the shape of the tool affects the weld joint's uniformity, plastic flow, heat generation, and power consumption. the majority of the heat is produced by the shoulder, which also keeps the plasticized material from escaping the workpiece. the material flow is influenced by both the tool pin profile and the shoulder. a number of new features have been added to tool design in recent years [1920]. the threads on the pin assist in ensuring that plastically deformed material flows around the pin as the tool advances along the joint line, it subsequently stirs and recombines the plasticized material to the side of the tool where the material cools to form a solid-state weld. at the end of the welding pass, the tool is retracted from the plate and leaves a hole at the end of the weld [21]. in recent years, several new classifications of features have been introduced. the primary classification of the currently used fsw tool geometries, such as a threaded cylinder, a threaded cylinder with flattened sides flared triflate,mx triflate, askew, and re-stir as shown in figure 2. enabled the successful welding of parts of higher t hickness by increasing the penetration depth. walaa h. ahmed al-khwarizmi engineering journal, vol. 20, no.2, p.p. 3955(2024) 41 fig. 2. tool geometry for friction stir welding [22]. 3. time line of the development of the geometry of the pin’s tool fsw was invented and patented by wayne thomas at the welding institute in 1991[23]. the tools used in fsw, including the geometry of the pin, have undergone several developments and improvements over time. the evolution of pin tool geometry started in the early stages of (1991). the initial development of fsw involved basic cylindrical or threaded pin geometries. basic shapes served as the primary tools initially; however, to enhance process comprehension, researchers experimented with varying pin lengths, diameters, and materials. in the late 1990s, researchers began exploring more intricate pin geometries to maximize material flow and mechanical properties. different pin shapes, including tapered and threaded designs, were scrutinized to enhance weld quality and efficacy[24]. by the early 2000s, tool geometry optimization was achieved through advanced computer simulations and modeling techniques. further enhancements were made to pin tool designs, focusing on aspects like flute geometry, shoulder diameter, pin offset, and probe materials to elevate welding performance. these efforts aimed to improve material flow, minimize defects, reinforce joints, and enhance process efficiency. ongoing research and innovation in fsw continue to refine and optimize pin tool geometries across various industries, as illustrated in the subsequent investigations [25]. 4. investigation on fsw pin shapes the researchers looked at different welding pin geometric shapes used in friction stir welding processes in this review. galvão et al., 2013 [26] investigated the effects of several fsw variables on the formation of intermetallic compounds (imcs), during friction stir welding of aa5186 to mild steel. the tool rotation speed was 355 rpm, welding speed was 1428 mm/min, 0.8 mm plunge depth ,5° tilt angle and the threaded pin tool was used in figure 3. they concluded that the low welding speeds of 14 mm/min were the tunnel defect first appeared, and that the making of thick imcs was what led to the joints at low welding speeds having unusually low tensile strengths. the imcs dropped and the joint's tensile strength increased as welding speed increased. from experimental work, they discovered that utilizing four pins (conical threaded, cylindricalconical threaded, stepped conical thread and neutral flared triflate) with a diameter of 4 and 3 millimetres did not stop the tunnel fault, but that using a standard threaded m3tool pin did, and a bell-shaped nugget formed in its place. they proved that the joint's tensile strength increased to 90% achieved by cylindricalconical threaded. as a result of insufficient bonding between the aluminum and the steel, the joint's strength decreased with faster welding speeds and shorter tool plunges. walaa h. ahmed al-khwarizmi engineering journal, vol. 20, no.2, p.p. 3955(2024) 42 fig. 3. pin profiles geometries. (a) conical threaded. (b) cylindricalconical threaded. (c) stepped conical thread (d) neutral flared triflate [26]. marzbanrad et al., 2014 [27]studied the effects of pin shape on the mechanical and microstructural flow of material, thermal distribution, and strain fields during the fsw of aa5083. two separate tools with square and cylinder pin shapes were used to create the joints. as depicted in figure 4. to investigate how tool pin profiles affect material flow, and temperature, and strain distribution, a numerical model is created using 3d fem— thermo-mechanically coupled rigid-viscoelastic and strain distributions. in the experimental work, a tensile test was performed. the outcomes found that square pin shapes offered finer grain structures and higher ultimate strengths than cylinder ones. these results can be explained by the square pin profile's higher deviation, large stirring zone, and greater weld zone temperature. fig. 4. square and cylindrical pin shapes [27]. doos, qasim m. and makki, 2014 [28] investigate the impact of fsw t–joints on the mechanical characteristics of aa 5456 plates with 4 mm thickness. the base material was cut into dimensions of 180×70×30 mm3 for stringers. this research looked at the impact of welding parameters such as rotating speed, transverse speed, plunging depth, and die radii of the gripping clamp on the efficiency of welding and the strength of welded parts. in the experimental work, the three rotational speeds (640, 960, and 1200) rpm and three welding speeds (60, 90, and 110) mm/min and three values for the tool tilt angle (2, 3, and 4) mm were used to achieve the best level of the welding condition that improves the weld quality. two tool geometries were used for fsw t-joints. the first tool had a square pin profile in two parts, the first part with (5×5×4) mm dimensions starting from the shoulder face with a 22 mm shoulder diameter and the second part with (3×3×1) mm dimensions from the end of the first part. the second tool had a conical pin profile with the basic dimensions (5mm base diameter, 3mm minor diameter, and 5mm length) and a 22 mm shoulder diameter. from the results of this work, the greatest welding efficiency for the aluminum alloy (al 5456) utilizing the fsw t-joint is 82.05%. mustafa, kadhym and yahya, 2015 [29] studied the influence of fsw t–joints for al 6061 t6 al alloy on mechanical and metallurgical characterization investigated by nine different tool shapes, that are fabricated by taguchi orthogonal array (oa) with no varying of process parameters (welding speed, rotation speed, die radii, tilt angle, and plunging depth) figure 5. four variable geometrical factors (diameter of shoulder: 14.1, 17.1, and 24.1), pin angle (0, 5, and 10), diameter of pin (1.7, 2.2, and 2.7), and shape of pin (smooth, right, and left) with three stages for each factor were utilized. the design of experiments (doe) was preceded by an l9 (orthogonal) array with 9 experiments. the best parameters were shoulder diameter = 17.1 mm, pin diameter = 2.2 mm, pin angle = 10°, the shape of the pin = right, utsskins actual mean = 168.00 mpa for the welded parts. walaa h. ahmed al-khwarizmi engineering journal, vol. 20, no.2, p.p. 3955(2024) 43 the best parameters are the same which give higher uts and ubf. fig. 5. manufactured tools [29]. dawood et al., 2015 [30] studied three various pin shapes namely; conical threaded,triangular , and square, as shown in figure 6. these pin shapes affect on the mechanical characteristics and microstructures of aa6061 joints. the outcomes show that triangular pin shapes produce the best metallurgical and mechanical weld characteristics. additionally, when utilizing a square tool pin shape, friction stir welding has the lowest microhardness and tensile strength. according to this, a more concentrated heataffected zone (haz) and an ideal amount of softening are produced by tool pin profiles and shoulder diameters that are lower. the fracture surface analysis demonstrates that during welding with various tool pin profiles, the joints undergo different types of failure. the specimens produced with triangular pins break during the tensile test with a malleable fracture, according to the fracture surface, while the joints formed with various pin shapes show brittle fracture modes (t1 and t3). fig. 6. (a) threaded tapered cylindrical pin shapet1, (b) triangular pin shapet2, (c) square pin shape t3 [30]. ilangovan et.al., 2015 [31] examined how various aa6061-aa5086 joints' mechanical properties were modified by the pin profile (cylindrical, threaded, and tapered pin). in the investigation, cylindrical pin profiles with threads and taper produced joints without defects and with comparable tensile properties. however, the result of this work shows that the threaded cylindrical is preferred due to the superior joints used in their research, as shown in figure 7. fig. 7. (a) cylindrical pin. b) threaded pin. c) tapered pin[31]. al-kubaisy, 2016[32] made an investigation to find the best fsw variables, the taguchi technique was utilized to identify essential variables for the dissimilar aa2024-t3 and aa7075-t73 of 3 mm thick plates respectively. using a variety of travel speeds (20, 45, and 69 mm/min), a variety of rotation speeds (898, 1200, and 1710 pm), three various pin shapes (cylindrical, threaded cylindrical, and cone), and a 2° tool tilt angle, fsw was successfully performed. the optimum parameter values were found using the s/n ratio analysis result, and they were 898 revolutions per minute for rotation, 45 millimeters per minute for travel speed, and a threaded cylindrical pin profile with a 76% joint efficiency. tensile strength statistics indicate that travel speed, which contributed 66.05% more than the other process variables, was the most important variable. sabari et al., 2016 [33] investigated the performance of different pin profiles on the fsw joint strength of aas5-t87-produced underwater cooling media. figure 8 shows the shapes of threaded taper cylindrical (stc), taper cylindrical (tac), threaded cylindrical (thc), and taper threaded cylindrical (ttc). the analysis was based on the characteristics of the rotated part and the resulting yield strength of every fsw junctions. from this observation, they found the joint with a taper-threaded pin-profiled tool and underwater cooling media demonstrated excellent tensile qualities, with joint effectiveness of 76% and tensile strength of 345 mpa walaa h. ahmed al-khwarizmi engineering journal, vol. 20, no.2, p.p. 3955(2024) 44 fig. 8. stc, tac, thc and ttc pin profiles[33]. kumar, 2017 [34] attempted to weld the aa7075 t651 and aa6061 t6 using the fsw process. the rotational speed (750 rpm 1250 rpm) and traverse range (90 mm/min 110 mm/min) were considered as the studied process parameters. pin profiles were created using 5 tools, including the threaded cylindrical (tc), triangular (tp), conical (cp), square (sp), and hexagonal (hp) profiles in figure 9. in this work, the results of the experiment showed that the square tool pin profile and the hexagonal pin profile produced good, clean welds when used at tool revolving speeds of 1250 rpm and 110 mm/min, respectively. the proper choice of tool pin profile, rotational speed, travel, and different necessary parameters will give better consequences. fig. 9. five pin shapes [34]. sharma et al., 2018[35] examined the impact of various pin profiles on the microstructure, material flow, and microhardness of the various joints during the fsw of commercially pure copper in a butt configuration and aa5754 al alloy. the pin profiles of taper, cylindrical, taper cam, taper cam, and square shape depicted in figure 10 are used to perform the joining. the welding speed is 40 millimeters/minute, and the rotational speed is 900 rpm. out of all the joint profiles, the square pin profile provides the best microhardness and joining. fig. 10. fsw tool pin profiles[35]. udaiyakumar et al., 2018 [36] made an investigation on different pin shapes (straight cylinder, straight square, and tapered hexagon) and fsw mechanical qualities on variant al alloys to evaluate how well they worked. three pin shapes and two alloy compositions, aa6061 and aa7075, were welded to examine the weld-joint behavior. microhardness tests were utilized to measure mechanical properties. in this work, the process parameters of each specimen were analyzed and correlated to highlight the qualities and characteristics. the result indicates that the straight square was chosen for microhardness. goel et al., 2018 [37] studied the aa6063-t6 butt joint produced by fsw. 5 distinct kinds of pin shapes (cylindrical (cy), tapered cylindrical (tcy), square (sq), triangular (tr), and hexagonal (hex)) were fabricated as shown in figure 11. the results showed that the highest tensile strength (162 mpa) using tcy was demonstrated, while the lowest tensile strength (115.6 mpa) was verified using a triangular shape. fig. 11. fsw tools pin profiles (a) cylindrical; (b) tapered cylindrical; (c) triangular; (d) square and (e) hexagonal[37]. amin, hanna and mohamed, 2018 [38] examined the impact of pin shapes on the mechanical characteristics of welding joints for aa6061-t6. to determine the best bobbin pin design, pin shapes and their effects on the mechanical properties of aa6061-t6 welding walaa h. ahmed al-khwarizmi engineering journal, vol. 20, no.2, p.p. 3955(2024) 45 joints that have a 6.25 mm thickness were investigated using fsw. five different pin shapes were used to create the welding joints: straight cylindrical with three flat surfaces, straight cylindrical with four flat surfaces, straight cylindrical with threaded surfaces, and straight cylindrical with threaded surfaces with three flat surfaces, figure 12. in the experimental work, tensile and bending tests were performed to determine the ideal bobbin tool design that had excellent mechanical qualities. based on tensile strength, the tool of straight cylindrical with 4 flats, an 8 mm pin, and shoulders with a 24 mm diameter given a higher strength (192 mpa), elongation (6.2%), bf (5.6 kn), and efficiency (65.3%). fig. 12. straight cylindrical with 4 flat surfaces that are threaded, straight cylindrical with 3 flat surfaces that are threaded, and straight cylindrical pins with 3 flat surfaces that are threaded[38]. maboud et al, 2018 [39] applied response surface methodology (rsm) to study the mechanical properties of friction stir processing of aa1050 by utilizing four factors (rotational speed 500, 1000, 1500, 2000, 2500), feed rate (58, 87,116, 145, and 174), number of passes (1, 2, 3, 4, and 5), and tool shape (conical,triangle, square, pentagon, and hexagonal) figure 13. the anova technique was used to identify the important process variables influencing the respondents' responses. according to these findings, the friction stir processing of 1050 aluminum alloy with three fsp passes, a square tool shape, the rotational speed was 1500 reovlutions per minute, and a welding speed was 116 millmeters per minute had a maximum efficiency of 72.9%. fig. 13. fsw tool pin profiles[40]. shammari, 2019 [41] investigated the mechanical properties of fsw butt joints made from aa2024t3 and aa6061-t6. the following parameters were chosen for this project: three-pin profiles (cylindrical, cylindrical thread, and triangular) showed in figure.14, rotation speed (550,950,1500 rpm), travel speed (40,60,80 mm/min), and tilt angle (1,2,3) degrees. they used the anova technique and the signal-to-noise ratio to identify the most important factor influencing the mechanical parameters of the weldment. the result of this work shows that the pin geometry has been found to have the smallest impact, whereas tilt angle has the biggest impact of all the parameters. the travel speed is the most influencial factor in the bending test, and the pin geometry still has the smallest impact. fig. 14. pin shapes geometry: a) cylindrical pin, b) cylindrical threaded pin, c) triangle pin [41]. su, xue and wu, 2020 [42] investigated the fsw's performance for three tool pins with three flats. the tool pin t0 is a conical pin, and the tool pins t30, t60, t90, and t120 have three flat areas with varying opening angles of 30°, 60°, 90°, and walaa h. ahmed al-khwarizmi engineering journal, vol. 20, no.2, p.p. 3955(2024) 46 120°, respectively. the measurements of the different tools are the same: figure 15 shows that the pin length is 5.75 mm, the pin diameter on top and bottom is 6.00 mm and 4.00 mm, respectively, and the shoulder diameter is 15.0 mm. for a thorough understanding of the coupled thermomechanical phenomena around the tool pin with three flats during fsw, a three-dimensional cfd model is utilized. a quantitative analysis is conducted to determine the impact of the pin flat proportion on the welding loads, material flow behavior, and thermal response. the findings show that the volume of the plastic deformation zone, maximum material flow velocity, temperature distribution, and heat generation rate all continuously increase as the proportion of flat features on the pin side increases. furthermore, it is discovered that the tool torque is not significantly affected by the tool pin profile (less than 4.7%), and that t90 provides the highest tool torque values. fig. 15. three tool pins with three flats[42]. shiva chander et al., 2020 [43] examined the aa6351 fsw weld joint's mechanical characteristics using five pin profiles (straight cylindrical, threaded cylindrical, taper cylindrical, square, and triangular) as figure 16 reveals. in accordance with tensile strength the triangle tool pin gave a mechanically sound and metallurgically free, disorder-free weld. fig. 16. straight cylindrical, threaded cylindrical, taper cylindrical, square pin geometries [43]. mustafa and daham, 2021 [44] conducted an investigation on the friction stir welding of t-joints made of aa6061-t6. by using the taguchi technique based on the l9 orthogonal array to investigate the effects of four process factors. these variables are: (transverse speed, type of nanopowders, rotational speed, and groove depth). the simultaneous creation of metal matrix nanocomposites (mmncs) and welding t-joint sections are combined. based on tensile tests conducted in the direction of the skin and stringers as well as a joint hardness test, optimum factors and their percentage contribution are determined using the(anova) technique and signal-to-noise ratio approaches. at the optimum conditions of 1550rpm rotational speed, the skin-welded part's best ultimate tensile stress (uts skin) equal to (177mpa) was obtained. travel speed of 15 mm/min, al2o3 powder, and a groove depth of 1 mm. all nine studies' metal matrix nanocomposite sem micrographs showed that the nanoparticles varied widely in the nugget zone as a result of one pass. the maximal hardness value of 80hv is obtained in the nugget zone at rotating speeds of 960rpm, transverse speeds of 15mm/min, type of powder tio2, and groove depths of 1.5mm. the groove's depth is the most important parameter in this experiment, the depth of the groove is the most important variable, according to the analysis of variance. nano-powder particles in the region of fsw improve the uts and hardness, but the powder clusters in this area will reduce the enhancement of these qualities. the cylindrical pin profile with 1.5mm grove depth is practical and walaa h. ahmed al-khwarizmi engineering journal, vol. 20, no.2, p.p. 3955(2024) 47 gives higher stirring of nanopowder in the nugget zone due to improving the hardness and tensile strength . jayaprakash et al., 2021[45] welded aa5083 and aa7068 by fsw using three pin profiles including triangle-shaped, tapered cylindrical, and straight cylindrical tools. as shown in figure 17. the investigation's process factors include force of (3, 4, 5, and 6) kn, rotational speed of (800, 1000, 1200, 1400) rpm, traverse speed of (30, 40, 50, 60) mm/min, and thickness of plates (5, 6, 7, 8) mm. the result of this work shows that the welding zone's improved hardness value and ultimate tensile strength are evidence that the tool profile was effectively put to use. at 267 mpa, the maximum uts was reached. the highest uts measured with a triangular tool was 286 mpa. a straight cylindrical tool was used to achieve the highest uts of 275 mpa. fig. 17. fsw tool. (a) cylindrical, (b) taper, (c) triangular tool [45]. battina et al., 2021 [46] studied the mechanical characteristics of welded joints by utilizing five pin profiles namely taper square (ts), straight pentagonal (sp), straight square (ss), straight cylindrical (sc), and straight hexagonal (sh). according to the test results, the straight square tool pin profile had a tensile elongation of 6.7% and a higher uts of 253 mpa. compared to other pin profiles, higher micro-hardness and joint efficiency were reported. for a straight square tool pin profile, figure 18, additional flow ability indications with fine grain structure were studied. the increase in micro-hardness was caused by the presence of a compound and the development of fine-grain structures. a joint without any flaws was created by the square pin profiles. fig. 18. various tool pin profiles [46]. gopi and mohan, 2021 [47] studied two geometrical tool parameters to properly define the pin profiles (triangle tr, square sq, pentagon pn,hexagon hx,heptagon hp) figure.19, five friction stir welding (fsw) processes were selected which are (spindle speed (700,900,1100,1300 and 1500), weld speed (0.8,1.6, 2.4, 3.2and 4.0), and shoulder penetration 0.00,0.04 ,0.08, 0.12 and 0.16), and shoulder profile (-10°, -5°, 0°, 5°and 10°). the taguchi experimental design approach was used for optimization, and fsw tests were carried out in a typical milling machine. for different plate thicknesses, the parameters were tuned to maximize the tensile strength. the corresponding welding pulses are determined by the number of tool pin polygon edges. the results show that 105– 110 pulses/s is the ideal rate for producing a highquality and defect-free weld. fig. 19.various tool pin profiles[47]. walaa h. ahmed al-khwarizmi engineering journal, vol. 20, no.2, p.p. 3955(2024) 48 ahmed et al., 2021[48] studied aa1050-h14 comparable lap joints by using the bobbin toolfsw method with a thickness of 10mm. by using three distinct pin geometries (cylindrical, square, and triangular), figure 20, as well as a concave shoulder profile. travel speeds of 200, 400, 600, 800, and 1000 millimeters/minute were used in addition to rotation speed of 600 revolutions per minute. the results demonstrated that pin shape and travel speed are regarded as the most crucial controlling parameters in bt-fsw thick lap joints. the temperature generated during the bt-fsw process was measured and studied at the joints' centre line. in comparison to the cylindrical (cy) and triangular (tr) pin geometries, the square (sq) pin produces the greatest bt-fsw stir zone temperature, while the tr pin produces the lowest stir zone temperature at all applied travel speeds between 200 and 1000 mm/min. additionally, the temperature at the lap joints dropped as welding speed increased, and the highest temperature of 380 °c was reached with sq pin at the slowest travel speed of 200 mm/min. by about 20 °c, the temperature on the advancing side (as) was greater than on the retreating side (rs). at all the different welding speeds examined, defect-free welds were created utilizing a bobbin tool with cy and sq pin geometries. when employing the sq pin, bt-fsw at a travel speed of 200 mm/min results in the maximum tensile shear qualities. the tool pin geometry and welding speed both had a substantial impact on the hardness profiles, although utilizing a triangular pin and increasing the welding speed significantly reduced the width of the softened region. fig. 20. (a) 3d pin shapes, and (b) dimension of bt pins [48]. raj et al., 2021 [49] made an investigation by using aa2024-t365 and aa5083-h111 as their base materials, and heat-treated h13 steel for the tool material. using three different pin profiles namely: (stepped, triangular, and square), with pin diameter of 5 mm, and a height of 4. 7 mm. the welding variables are the tool rotational speed of 900, 1120, and 1400 revolutions per minute and the travel speed of 16, 40, and 80 millimeters per minute. the plate cuts into aa5086 (100*95*6 mm) and (100*70*6 mm). the optimum variables were (a rotational speed of 1000 revolutions per minute, a traverse speed of 20 millimeters per minute, and tilting angle of 2ᵒ). the maximum impact strength of joints was achieved when using a triangular pin profile. ahmed et al., 2022 [50] optimized the fsw parameters of the aa5451 alloy by using taguchi experimental design. the process variables have significant effects on the welded joint with the fsw method i.e., feed rate (16, 18, and 20 millimeters per minute), rotational speed (1000,1200 and1400 revolutions per minute), and pin profile (taper,threaded and cylindrical) of the tool, figure 21. when the welding conditions were used, which included a rotation speed of 1400 revolutions per minute, a welding speed of 18 millimeters per minute, and a tool pin with threads, the maximum value of ts, or 160.57 mpa was achieved. using an optimal setup of 1200 rotating speed and a welding speed of 18 millimeters per minute with pin profile containing threads, 81 hv the highest hardness was obtained. fig. 21. tool profiles in the fsw process [50]. walaa h. ahmed al-khwarizmi engineering journal, vol. 20, no.2, p.p. 3955(2024) 49 table 1, presented in detail, illustrates the shapes and their variables, contributing to a better understanding of welding operations. summary of the findings for some fsw-selected literatures with different tool geometries. no . authors name year tool geometry work piece material weld joint fsw joint efficiency merits drawbacks remark 1 galvão et al., 2013 conical threaded nut threaded in a cylindrical-conical shape. conical thread with steps. an unflappable homage. al5186 butt joint 90% tensile strength increased to 90% of the strength of base alloy insufficient bonding between the aluminum and the steel the flat shoulder produces defective welds. 2 marzbanrad et al., 2014 square and cylindrical pin shapes aa5083 butt joint 65% square pin profile's higher deviation, large stirring zone, and greater weld zone temperature failure location of the tensile test specimens was at the retreating side of the sz. the peak temperature of the square pin was favorable for the solid diffusion and plasticized mixing. 3 doos, qasim m. and makki, 2014 square pin, conical pin aa 5456 t–joint 82.05 % improves the weld quality the tunnel defect was raised from the top to the bottom of the weld welding parameters with the least heat input resulted in minimum hardness. 4 mustafa, kadhum and yahya 2015 nine varied tool shapes aa 6061 t6 t–joint 67% improves the weld quality the excessive heat of the process leads to low mechanical strength the best parameters when shoulder diameter = 17.1 mm, pin diameter = 2.2 mm, pin angle = 10°, shape of pin = right 5 dawood et al. 2015 tapered threaded cylindrical,triangula r , and square aa6061 butt joint 54% triangular pin shapes produce the best metallurgical and mechanical weld characteristics a square tool pin shape has the lowest microhardness and tensile strength. ductile fracture appears in t1, t3 6 ilangovan, et al., 2015 cylindrical pin,threaded pin and tapered pin aa 6061 – aa 5086 butt joint 65% threads and taperproduced connections without defects the straight cylindrical pin profile tool yielded crosssectional macro-level defects in the stir zone improved tensile strength 7 al-kubaisy, 2016 cylindrical, threaded cylindrical, and cone aa2024t3 and aa7075t73 butt joint 76% the tensile strength increases with increasing the welding speed the coarsening reduced the hardness in haz traverse speed was the most important variable 8 sabari et al., 2016 threaded taper cylindrical, taper cylindrical, threaded cylindrical, taper threaded cylindrical aa2519t87 butt joint 76% taper threaded pin gives excellent tensile qualities the tmaz showed minimum hardness defect-free weld 9 kumar, 2017 threaded cylindrical,triangula r , conical, square, and hexagonal aa7075 t651 and aa6061 t6 butt joint 56% square tool pin profile and the hexagonal pin profile produced the macrostruct ure of specimen 4 has a defect good quality welding walaa h. ahmed al-khwarizmi engineering journal, vol. 20, no.2, p.p. 3955(2024) 50 good, clean welds when used at tool revolving speeds 10 sharma et al., 2018 2018 cylindrical, taper, cylindrical cam, taper cam and square aa5754 butt joint 68% the square pin produce good joining defect-free joining in square pin profile square pin profile showed good welding and hardness 11 udaiyakum ar et al., 2018 straight cylinder, straight square and tapered hexagon aa6061 and aa7075 butt joint 71% straight cylinder tool pin profile an added advantage over other profiles some samples of square and taper hexagon tool pin profiles have sharp edge the straight square is chosen for microhardness 12 goel et al., 2018 cylindrical, tapered cylindrical, square , triangular , and hexagonal aa 6063-t6 butt joint 59% the highest tensile strength (162 mpa) using tapered cylindrical was demonstrated the lowest tensile strength (115.6 mpa) was verified using a triangular shape. hooking, kissing and zigzag line defects were observed in the weld zone 13 amin, hanna and mohamed, 2018 straight cylindrical with 4 flat surfaces that are threaded, straight cylindrical with 3 flat surfaces that are threaded, and straight cylindrical pins with 3 flat surfaces that are threaded aa6061t6 bobbin joints 65.4% free-defect weld joint the substrate thickness and the space between the tool shoulders must match the tool of straight cylindrical with four flats, an 8 mm probe and a 24 mm shoulder diameter giving better tensile strength 14 martin et al., 2018 conical, triangle, square, pentagon and hexagonal aa1050 butt joint 72.9% the square pin profile provides good joining and microhardness cylindrical cam profiles result in defect-free joining defect free 15 shammari, 2019 cylindrical, cylindrical thread, and triangular aa2024 t3 aa6061 t6 butt joint 65% tilt angle has the biggest impact of all the parameters the pin geometry still has the smallest impact. optimum welding parameters gave good quality and no defects 16 su, xue and wu, 2020 conical tool pin aa2024 butt joint 74% the maximum value of tool torque is achieved by using t90 less than 4.7% is the impact of the pin shape on the tool torque. free weld defect 17 shiva chander et al., 2020 straight cylindrical, threaded cylindrical, taper cylindrical, square, and triangular aa6351 butt joint 66% that square and threaded device pin profiles give highest tensile strength improved the weld quality 18 mustafa and daham, 2021 nine pin profiles 6061t6 with nanocom posites material t-joint 64% the most important factor is the depth of the groove the fact that the use of a 0.5 mm groove’s depth is not practical nano-powders additives improve mechanical properties and hardness 19 jayaprakas h et al., 2021 triangle-shaped, tapered cylindrical, and straight cylindrical aa5083 and aa7068 butt joint 85% cylindrical taper tool produces maximum hardness the triangular tool provided the minimum hardness improved hardness value and ultimate tensile strength walaa h. ahmed al-khwarizmi engineering journal, vol. 20, no.2, p.p. 3955(2024) 51 1 2 5. discussion from the literature survey, it is obvious that samples that are welded with a square pin shape have superior mechanical characteristics (ys, uts, te, and microhardness) than samples that are welded with other pin profiles. this improvement is attributed to a finer recrystallized grain structure and fewer defects. notably, void defects significantly impact tensile characteristics and substantially reduce tensile strength. consequently, the triangular pin profile demonstrates a lower uts value of 54%. the enhanced characteristics of the square pin are due to the higher dynamic-to-static volume ratio at its corners, thereby creating more driving force. the materials' velocity and heat production during the fsw tool's stirring procedure cause the movement of materials in the fsw joining process. material flow predominantly concentrates in the rs, where all fsw samples have significantly greater stirring procedures. the material motion in the rs was greater than in the as, which can be explained by this occurrence. additionally, it is observed that the maximum temperature remains below the tool. this is explained by the material on the workpiece's upper surface proceeding parallel to the tool's shoulder, resulting in a higher shear rate and increased heat generation. these findings align with previous research [48]. reaching the maximum temperature during the welding process requires more time when utilizing the triangle pin tool. as a result, insufficient dynamic recrystallization caused by heat loss in the stirred zone results in joints with reduced strength and weak joint efficiency. in contrast, the pulsating action of sharp flats and related frictional heating causes the square pin profile to produce highertemperature and plasticized material. the creation of heat decreases with increasing tool mechanical action. the symmetrical internal heat distribution at a higher pin angle augments mechanical action, decreasing the viscosity of the material and enhancing the stirring behavior, or material flow around the pin. a larger stir zone forms in the joint area as a result of the enhanced stirring procedure caused by the increased plastic flow near the tool. 6. limitations and challenges of the fsw method despite the big efforts that have been made by the research centers and investigators to develop 20 battina et al., 2021 2021 taper square,straight pentagonal,straight square, straight cylindrical, and straight hexagonal aa6061t6 and aa2017t6 butt joint 67% a straight square tool pin profile has higher microhardness and joint efficiency the joint made with the sc pin profiled tool has a lower uts a joint without any flaws was created by the square pin profile's pulsing activity 21 gopi and mohan, 2021 triangle tr, square sq, pentagon pn ,hexagon hx ,heptagon hp aa6082t6 butt joint 94% the tensile strength improved reduction in weld strength caused by the formation of coarse grain 105–110 pulses/s is the ideal rate for producing a highquality and defectfree weld. 22 ahmed et al., 2021 cylindrical, square, and triangular aa1050h14 lap joints 89% defect-free welds were created utilizing a bobbin tool with cy and sq pin geometries the hardness values of the stir zone are lower than those of the bm defect-free 23 raj et al., 2021 stepped, triangular, and square aa2024t365 and aa5083h111 butt joint 72% triangular pin tool has the maximum strength the stepped pin tool has the minimum strength output values increase with a lower feed rate 24 ahmed et al., 2022 taper,threaded and cylindrical aa5451 butt joint 80.5% thread pin shape produced the highest tensile strength tool rotation speed has the least effect on hardness free defect weld walaa h. ahmed al-khwarizmi engineering journal, vol. 20, no.2, p.p. 3955(2024) 52 and improve fsw performance, it still faces some challenges and involves some limitations that need to overcome, and requires effective solutions to enhance the productivity and performance of the process. some demerits and challenges are listed below. 1. cost. the initial cost of fsw equipment and tooling is high, which may deter smaller manufacturers from adopting the technology. 2 skilled labor. fsw requires skilled operators to set up and operate the equipment, and a shortage of skilled personnel can be a limitation. 3 material limitations. fsw is most effective on certain materials, like aluminum and some alloys. it may not be suitable for all materials, limiting its applications. 4. size constraints. fsw machines are often limited in terms of the size of the components they can weld, which can be a limitation in larger manufacturing processes [51]. 5. exit hole. it is generally desired to eliminate the exit hole at the end of conventional friction stir welds, and to remove the exit hole one should cut it from the end of welding [52]. 7. conclusion recent research indicates that fsw pin profiles significantly influence material flow and mechanical properties. the friction stir welding method has effectively joined both similar and dissimilar aluminum plates especially in the circumferential welds. it has been observed that the mechanical properties and joint strength are substantially affected by the configurations of various pin profiles. 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(2024) 39-55، صفحة 2، العدد20مجلة الخوارزمي الهندسية المجلد والء حافظ احمد 55 األداة في لحام االحتكاك الحركيالدراسات السابقة لهندسة دبوس ، محمود شكور***علي حسين كاظم **، والء حافظ احمد *  العراق ،جامعة بغداد ،كلية الهندسة الخوارزمي ،المؤتمت*،**قسم هندسة تصنيع اماليزي ،هانج تواه جايا ،ملقاالجامعة الماليزية التكنولوجية ،والهندسة كلية تكنولوجيا الصناعة والتصنيع ،قسم هندسة التصنيع*** walaa.abbas1604@kecbu.uobaghdad.edu.iq :البريد االلكتروني* kadhumali59@yahoo.com :البريد االلكتروني** shukor@utem.edu.my: البريد االلكتروني*** المستخلص هو طريقة للحام في الحالة الصلبة اذ يتم تكوين اللحام تحت درجة انصهار المعدن القاعدي. المواد ذات نقطة انصهار عالية (fsw) لحام مزج االحتكاك ً في انشطة بحث تم إجراء العديد من الدراسات على المعادن القابلة لالنصهار بشكل عالي مثل الفوالذ ، (fsw) وكذلك المواد اللينة تلقت مؤخراً اهتماما اجرت العديد من الدراسات تحقيقات حول سرعات والتيتانيوم وغيرها. جودة اللحام تتأثر بعوامل متعددة مختلفة ومن اجل الحصول على افضل جودة للحام، ، عامل اخر حاسم يؤثر في جودة اللحام هو هندسة األداة. هدف هذا البحث هو تقييم تطور مالمح مختلفة للدبوس االنتقال والدوران كمعلمات عملية رئيسية ي تم نشرها. بحسب وكيف تؤثر في البنية المجهرية والخصائص الميكانيكية للحام. أظهرت المالمح المربعة للدبوس انها تنتج وصالت قوية، وفقاً لألبحاث الت الملولبة شير إلى ان االسطوانات الملولبة او التفاوت الملولب يقدمان اتصاالت متفوقة. االستنتاج الذي يتفق عليه جميع االبحاث هو ان الهياكل ابحاث اخرى، ت .هي االكثر فعالية على اداء االداة  mailto:walaa.abbas1604@kecbu.uobaghdad.edu.iq mailto:kadhumali59@yahoo.com _89-100_ mohammed i. younis 89 a fully computerized method to backup the router configuration file mohammed i. younis dr. ghassan h.majeed college of engineering computer center baghdad university baghdad university (received 17 october 2006; accepted 19 september 2007) abstract: this paper presents a fully computerized method to backup the router configuration file. the method consists of a friendly graphical interface programmed by java programming language. the proposed method is compared with the two existing methods, namely: tftp server method and copy/paste method. the comparison reveals that the proposed method has many advantages over the existing ones. the proposed method has been implemented on cisco routers (series 2500, 2600 and 2800). keywords:cli, router, tftp, gui, nvram, hyper terminal introduction: communication between different networks requires special networking devices called routers (fig.1). the purpose of a router is to examine incoming packets (layer 3 data), choose the best path for them through the network and then switch them to the proper outgoing part [1]. this means that routers are the most important traffic-regulating devices on large networks .in short routers let virtually any type of computer communicate with any other computer anywhere in the world [2]. routers require configuration before performing the above function. configuration includes the followings [3]: • password setting. • routing protocols setting. • routing tables setting. • ip addresses of the interfaces. • access lists setting. • advanced security setting. all these settings are saved under one file (called configuration file). this file is stored in a nonvolatile random access memory (nvram), alkhwarizmi engineering journal vol.3 , no.3 , pp 89-100 (2007) alkhwarizmi engineering journal mohammed i. younis /al-khwarizmi engineering journal ,vol. 3, no.3, pp 89-100 (2007) 90 which retains content when the router is powered down or restarted [4]. to configure the router, we have to first establish a connection with the router (hardware side) and second use a special application (software side) to define the above settings. hardware side: fig.2 shows the connection parts of a cisco router. as can be seen, two management ports are existed: the console port and the auxiliary port. most network administrators preferred the console port because it displays router startup, debugging and error messages by default. to connect to the console port with the pc a rollover cable and an rj-45 to db-9 adapters are used as shown in fig.3. software side: to define the parameters of the configuration, the user has to use a text or graphic mode interface. the application that provides these interfaces called terminal emulation applications .table.1 lists the available emulation for the well known operating systems. fig.4 shows the hyper terminal emulation used by microsoft operating systems. the literature [5] suggested two methods to create the configuration file: using the setup mode and using the command line interface (cli). setup mode is not commonly used because of the limits in what the user can actually configure. in the cli mode, the commands are entered by the administrator and executed one line at a time. the results of execution are stored in the ram of the router and called a running configuration, which can be saved on the nvram with any name and extension. literature refers to this file as a startup configuration file. the administrator may spend a long time when configuring the router, so it is recommended to back up the startup configuration file. cisco's experts presented two methods to backup the startup file: • using trivial file transfer server. • using copy/paste. the first method is simple and quick, but it requires special software to be installed on the pc and also requires an ethernet connection (network connection) between the ethernet port of the pc and the ethernet of the router. this connection can not be established without a previous setting of ip address of both ports. the second method does not require a special software or ethernet connection, but it is time consuming and needs a human intervention. the purpose of the present work is to suggest a simple, quick and fully computerized method to back up the configuration file without the need of an ethernet connection and any special software. in the following sections, we will describe and analyze the above two methods using windows xp [6] as operating system. tftp server method this method includes the following sequential steps: 1. connect the ethernet port of the pc with the ethernet of the router using cross-over utp cable. 2. assign the ip address of the ethernet port of the pc. 3. install the tftp server software on the pc. 4. execute the hyper terminal emulator on the pc. mohammed i. younis /al-khwarizmi engineering journal ,vol. 3, no.3, pp 89-100 (2007) 91 5. go to the global level and assign the ip address of the ethernet port of the router. 6. from the privilege level, issue the command : copy run tftp the above steps will save a backup copy of the running configuration file on the tftp server. the restoring process is done by repeating steps 1 through 5 then issue the command copy tftp run. copy/paste method this method consists of three parts (capturing, filtering and restoring): part one: capturing the configuration file 1. open the hyper terminal emulator with default setting (baud rate=9600 bps, 8 databits, no parity, 1 stop-bit, no flow control [7]). 2. go to the privilege level by using enable command. 3. from the transfer menu, click capture text. 4. specify the name for the text file to save the capture configuration. 5. from the sub menu of the capture text click start. 6. display the current configuration by entering (at the prompt) show run. 7. press the space bar when each –moreprompt appears, which continues with the configuration until the end is reached. 8. when the complete configuration has been displayed, select the stop from the sub menu of the capture text. after completing the above steps, all the displayed information will be saved on hard disk under the name specified in step 4. part two: editing the file in this part, the network administrator can perform the following: 1. filtering the capturing file by removing the lines that will cause errors when executing the file. 2. adding comments to the file by beginning lines with an exclamation mark (!). 3. adding some necessary commands, like no shutdown at the end of each of the interface section. the lines that must remove include: • show running-config • building configuration... • current configuration: • more • any lines that appear after the word end. the administrator can use any text editor (like notepad) to edit the file and then save the clean version of the configuration file. part three: restoring the file this part includes three operations: erasing the startup configuration file (from the nvram), restoring the clean configuration file (from the hard disk) and copying the clean file to the nvram through the console port. these operations can be achieved by the following steps: 1. from privilege mode, issue the command erase start. 2. from privilege mode, issue the command reload. 3. go to global level (by entering conf t). mohammed i. younis /al-khwarizmi engineering journal ,vol. 3, no.3, pp 89-100 (2007) 92 4. in the hyper terminal window, select text file from transfer menu. 5. select the name of the clean file. 6. the lines of the file are entered into the router as if they are being typed (stored in the ram). 7. exit the global level by pressing ctrl+z. 8. from the privilege level, copy the running configuration to the nvram with copy run start. 9. in order to check for changes to take effect the router must be reloaded. by issuing reload command from hyper terminal. the above procedure reveals that copy/paste method is tedious and requires human intervention in every step of the three parts. this of course makes it subject to several errors, like missing or error typing. also some literature suggested to use object originated programming for router configuration in terms of modular design but still have limitation of using cli[8][9][10]. the proposed method we use java programming language to implement a friendly graphical user interface (gui), as shown in fig. 5.this interface including scrollable text area, six buttons, and status bar. clicking on any of the buttons will result in executing one or more java objects to perform certain functions. before using the program the pc must be connected to the console port of the router using rollover utp cable with default setting. bellow is a description of how to use the proposal method: • execute the program by double clicking its icon (fig. 5 will be displayed). • click the capture button to display the content of the current configuration (running configuration), the status bar indicates that the capture is done (fig. 5). in compare with the copy/paste method, one click on the capture button is equivalent to the 8 steps maintained in part one. • the filter button is used to filter the captured file by removing the extra lines. the filtered content is displayed on the text area and the status bar indicates that the filtering is done (fig. 6). this step is replacement of tedious task for removing extra lines; that is done by the program not by the administrator. • click the edit button to add extra commands or comments, this button is used to toggle (enable/disable) the editing in the text area; the status bar indicates whether the text area is editable or not (fig. 7). the text editor included in the program and not requires third party programs (such as text editor). • the send button is for saving the clean file to the nvram of the router. using the default configuration file name (router-config) and the status bar indicate that the sending is done. in compare with the copy/paste method, one click on the send button in he proposed method is equivalent to the first 8 steps maintained in part three in copy/paste method (fig. 8). mohammed i. younis /al-khwarizmi engineering journal ,vol. 3, no.3, pp 89-100 (2007) 93 • the save button is for saving the clean file to the hard disk, the administrator will choose the backup file name and in which directory the saving is done. the status bar indicate that the file saving is done (fig. 9). the filtering, edit, and saving buttons in the proposed method are the replacement of part two in copy/paste method. • the reload button is designed to reload the router. it is equivalent to use reload command from the hyper terminal, but we add it to enable the user to perform reloading without using the hyper terminal emulator. i.e., replacement of step 9 maintained in part three in copy/paste method. conclusions 1. a fully computerized method to backup the router configuration file has been proposed in this work with friendly gui and easy to use. 2. the proposed method has the following advantages over tftp server method: • it dose not require the hyper terminal software. • it dose not require an ethernet connection between the pc and the router. • it dose not require a special software such as a tftp server software and text editor. 3. the proposed method has the following advantages over copy/paste method: • it dose not require the hyper terminal software and text editor. • it is very simple and quick. • it is time conversing. • the administrator dose not requires entering any command to perform the backup operation. mohammed i. younis /al-khwarizmi engineering journal ,vol. 3, no.3, pp 89-100 (2007) 94 fig. 1 internal configuration of the router fig. 2 external connection of 2600 routers mohammed i. younis /al-khwarizmi engineering journal ,vol. 3, no.3, pp 89-100 (2007) 95 fig.3 console port to pc connection fig. 4 hyper terminal emulator program mohammed i. younis /al-khwarizmi engineering journal ,vol. 3, no.3, pp 89-100 (2007) 96 fig.5: capturing the running configuration of the router fig. 6: filtering the captured configuration of the router mohammed i. younis /al-khwarizmi engineering journal ,vol. 3, no.3, pp 89-100 (2007) 97 fig. 7: enable the text area fig.8: sending the configuration to nvram mohammed i. younis /al-khwarizmi engineering journal ,vol. 3, no.3, pp 89-100 (2007) 98 fig. 9 saving the configuration to hard disk table 1 list of operating systems and the terminal emulation software that may be used mohammed i. younis /al-khwarizmi engineering journal ,vol. 3, no.3, pp 89-100 (2007) 99 list of abbreviations cli command line interface gui graphical user interface nvram non volatile random access memory pc personal computer tftp trivial file transfer protocol utp unshielded twisted pair cable references 1. “computer networks”, andrew s. tanenbaum, fourth edition, prentice-hall, inc., 2003. 2. "ccna1: networking basic v3.1", cisco systems, inc., 2003. 3. "networking lab practice kit for microsoft and cisco systems", john chirillo, john wiley and sons, inc., 2002. 4. "ccna cisco certified network associate study guide", todd lammle, 5th edition, sybex, inc., 2005. 5. "ccna2: router and routing basic v3.1", cisco systems, inc., 2003. 6. "hp it essentials i: pc hardware and software v3.1", cisco systems, inc., 2003. 7. "hardware troubleshooting for the cisco 2600 series router", cisco systems, inc., 2006. 8. "router plugins: a software architecture for next generation routers", dan decasper, zubin dittia, guru parulkar, and bernhard plattner. in proc. acm sigcomm conference (sigcomm '98), pages 229-240, october 1998. 9. "the click modular router", eddie kohler, robert morris, benjie chen, john jannotti, and m. franskaashoek,. acm trans. computer systems, november 2000. 10. "programming language techniques for modular router configurations", eddie kohler, benjie chen, m. frans kaashoek, robert morris, and massimiliano poletto, parallel and distributed operating systems group, laboratory for computer science, mit, cambridge, 2002. mohammed i. younis /al-khwarizmi engineering journal ,vol. 3, no.3, pp 89-100 (2007) 100 طریقة الكترونیة كاملة لحفظ نسخة احتیاطیة من ملف ترتیب الموجھ غسان حمید عبد المجید. د محمد عصام یونس مركز الحاسبة االلكترونیة، جامعة بغداد كلیة الھندسة، جامعة بغداد :صةالخال تحتوي ھذه الطریقة على . یعطي البحث طریقة الكترونیة كاملة لحفظ نسخة احتیاطیة من ملف الترتیب للموجھ .اة االستخدام والمبرمجة بلغة جافواجھات الصدیقة للمستخدم والسھل ھيالبدیطریقة خادم نظام إرسال الملفات :الطریقة المقترحة قورنت مع الطریقتین التقلیدیتین، وھما )(tftp server اللصق /وطریقة النسخ)copy/paste(، حیث تحتوي ھذه الطریقة على العدید من الفوائد إذا ما قورنت بالطریقتین الحالیتین ). ٢٨٠٠، و ٢٦٠٠، ٢٥٠٠سلسلة (الطریقة المقترحة قد طبقت على موجھات سسكو microsoft word ????? ????8-17 al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 17, no. 2, june, (2021) p. p. 8-17 prediction of surface roughness after turning of duplex stainless steel (dss) osamah f. abdulateef department of automated manufacturing engineering / al-khwairzmi college of engineering/ university of baghdad/ iraq email: drosamah@kecbu.uobaghdad.edu.iq (received 8 december 2020 ; revised 4 january 2021; accepted 19 january 2021) https://doi.org/10.22153/kej.2021.01.001 abstract feed forward back propagation artificial neural network (ann) model utilizing the matlab neural network toolbox is designed for the prediction of surface roughness of duplex stainless steel during orthogonal turning with uncoated carbide insert tool. turning experiments were performed at various process conditions (feed rate, cutting speed, and cutting depth). utilizing the taguchi experimental design method, an optimum ann architecture with the levenberg-marquardt training algorithm was obtained. parametric research was performed with the optimized ann architecture to report the impact of every turning parameter on the roughness of the surface. the results suggested that machining at a cutting speed of 355 rpm with a feed rate of 0.07 mm/rev and a depth of cut 0.4 mm was found to achieve lower surface roughness with, an increase in the cutting speed and feed rate with the increases of the surface roughness. in addition, an increase in the depth of cut was found to reduces the surface roughness. the outcome of this study showed that ann is a versatile tool for prediction of surface roughness and may be easily extended with greater confidence to various metal cutting processes. keywords: artificial neural network, cutting depth, cutting speed, feed rate, orthogonal array, taguchi method. 1. introduction metal cutting is one of the most commonly utilized manufacturing processes, the improvement in the performance of these processes and productivity based on cutting parameters like cutting tool geometry, cutting conditions in addition to the tool material and workpiece is essential. the surface feature is an essential parameter for determining the performance of machine tools and parts. therefore, achieving the required surface quality is of great importance for the practical behavior of mechanical parts. the surface roughness is a widely utilized indicator of product quality in terms of various parameters such as fatigue life improvement, tribological considerations, corrosion resistance, etc. today, particular consideration is given to dimensional precision and surface finish in every manufacturing industry [1]. thus, it is possible to consider the measurement and characterization of the surface finish as a predictor of machining efficiency. the mechanism of surface roughness creation is very dynamic, complex, and processdependent. variety of factors like cutting fluid, cutting parameters, and the hardness of the workpiece have been found to affect surface roughness in the turning process in different amounts [2]. several studies on surface roughness of different materials have been performed; the optimal cutting conditions are calculated most of the time utilizing the “taguchi method” and by combining empirical models with different optimization algorithms based on roughness and artificial neural network (ann). gokkaya and nalbant [3] examined the impact of feed, spindle speed, and coating type on surface roughness with osamah f. abdulateef al-khwarizmi engineering journal, vol. 17, no. 2, p.p. 817 (2021)     9 various spindle speeds. they finalized that surface roughness is inversely commensurate with the spindle speed. nalbant et al. [4] examined the prediction of surface roughness considering process parameters in the operation of cnc turning. to predict the surface roughness, they utilized a neural network with regression models. they concluded that the estimation of surface roughness utilizing neural networks was consistent with regression models. the impacts of cutting parameters on surface finish when turning composite materials utilizing “taguchi experimental design techniques” have been studied by palanikumar and karthikeyan [5]. they concluded that the approach studied may be utilized to research the impact of surface roughness with a 95 percent confidence level in al/sic-mmc composites. javidi et al. [6] investigated the impact of feed rate and tool nose radius on maximum surface roughness. to evaluate optimum cutting conditions utilizing the “taguchi method”, dave et al. [7] examined surface roughness in turned machine parts. they concluded that in machining processes, surface roughness has a significant effect. lavanya et al. [8] developed a predictive model on the basis of “ann” for the prediction of aisi-1016 surface roughness during orthogonal turning with cbn insert tool. the experiments of turning were performed at various process conditions utilizing full factorial design. feed rate, cutting speed and depth of cut, were the input parameters while the surface roughness was the output variable. the obtained results concluded that ann is dependable method, and it can be easily used to various metal cutting processes with higher confidence. kant et al. [9] joined the ann along with a geneticalgorithm (ga) for surface roughness prediction and optimization. vaibhav and sachin [10] investigated boring aluminum material on cnc machining taking into account spindle speed, feed rate, and depth of cut to get minimum surface roughness utilizing the "taguchi method". they suggested that the most important parameters for surface roughness are depth of cut and spindle speed. das et al. [11] investigated surface roughness in cnc turning taking into account feed rate, cutting depth, and spindle speed utilizing the "taguchi method". the verification of these parameters was justified by utilizing "taguchi method". gupta and kumar [12] examined surface roughness and material removal rate in turning operation utilizing the "taguchi method", taking into account rake angle and nose radius of the tool, feed rate, spindle speed, and cutting depth. they finalized that surface roughness increases with feed rate. sonali et al. [13] examined optimum machining parameters considering surface roughness on aluminum 6061. they concluded that feed rate, depth of cut, spindle speed, and nose radius had a significant effect on surface roughness. dahbi et al.[14] researched turning 2017a aluminum alloy utilizing a cnc lathe machine to calculate different cutting parameters. utilizing ann, they investigated the cutting parameters and their impact on surface roughness. the formulated ann network founded that the experimental result was in near agreement with the predicted results. pawan and misra [15] suggested an enhanced predictive model for dss turned component  surface roughness. the impact of different input cutting parameter namely feed rate, cutting speed, and approach angle are taken into account for the established model. the l9 orthogonal array on a turning machine with analysis of variance were utilized to examine the impact of process parameters on surface roughness. they concluded that the feed rate was the most important factor followed by cutting speed and approach angle. joshy et al. [16] performed cnc turning operation on the material of aluminum alloy 7075 and the surface roughness was conducted by considering machining parameters like feed rate, depth of cut, and spindle speed. the optimization of the process was carried out utilizing “analysis of variance (anova)”. the prediction of surface roughness has been carried out utilizing the "feed-forward backpropagation ann method”. suresh et al. [17] investigated the impact of cutting parameters on surface roughness creation in machining of duplex stainless steel (dss) with tin coated carbide tool. taguchi technique is utilized for optimizing the cutting parameters. l27 orthogonal array was utilized to conduct the experimental trials. the obtained results indicated that the surface roughness decreases with increase in cutting speed and low feed rate. elsadek et al. [18] applied “ann” and response surface methodology (rsm) predictive tools for predicting "surface roughness" on hardturning of aisi h13 hot work steel. it is noted from the above literature that many studies have been studied for different materials utilizing the ann method to optimize surface roughness. hence, the present study analyzes the effects of cutting speed, feed rate, and depth of cut on surface roughness ra by developing ann models during turning of dss by utilizing an uncoated carbide insert tool. firstly, process parameters influencing surface roughness were osamah f. abdulateef al-khwarizmi engineering journal, vol. 17, no. 2, p.p. 817 (2021)     10 covered by utilizing the "taguchi method". the experimental results are based on the design of the experiment that has subsequently been utilized for training the ann model. finally, experimental confirmations are carried out on the developed model, and comparisons are made between experimental and predicted results of ann. 2. methodology 2.1 experimental procedure in the present work, the used workpiece material is dss bar of 300 mm length and 50 mm in diameter. utilizing the psg-a141 traditional lathe machine with an uncoated carbide insert tool, dry turning is performed on all workpieces as shown in figure 1. for the experimental design, taguchi's l27 orthogonal array is selected. the experiments are carried out by changing the process parameters and the mean surface roughness values (ra) with a sampling length of 5 mm were measured. table 1 shows the considered cutting parameters and their levels. fig. 1. turning process in experimental work. table 1, control factors and levels control factors units level 1 level 2 level 3 cutting speed, v rev/ min 355 230 150 feed rate, f mm/min 0.3 0.13 0.07 cutting depth, d mm 0.6 0.4 0.2 an experimental plan is needed to build a simulation model on the basis of the ann that concerns to the average surface roughness and cutting parameters. often, the classic experiment design is too complicated, considerable time, and difficult to use. therefore, the taguchi design of the experiment has been included in the current investigation. three cutting parameters were considered, cutting speed (v), feed rate (f), and cutting depth (d). based on the prior studies, the process parameter ranges were chosen. the process parameters were organized in the l27 orthogonal array of standard taguchi. the twenty-seven pieces are machined utilizing the above set of values and surface roughness (ra) values are reported in table 2 utilizing the microroughness tester tr220 as shown in figure 2. fig. 2. tr220 micro roughness device when measuring surface roughness. osamah f. abdulateef al-khwarizmi engineering journal, vol. 17, no. 2, p.p. 817 (2021)     11 table 2, experimental values of surface roughness ra. exp. no. cutting speed (v) rev/min feed rate (f) mm/min cutting depth (d) mm roughness (experimental) µm 1 355 0.3 0.6 2.577 2 355 0.3 0.4 2.789 3 355 0.3 0.2 2.89 4 355 0.13 0.6 2.376 5 355 0.13 0.4 2.949 6 355 0.13 0.2 2.819 7 355 0.07 0.6 2.14 8 355 0.07 0.4 1.7545 9 355 0.07 0.2 3.647 10 230 0.3 0.6 2.464 11 230 0.3 0.4 3.216 12 230 0.3 0.2 3.53 13 230 0.13 0.6 2.714 14 230 0.13 0.4 2.975 15 230 0.13 0.2 3.096 16 230 0.07 0.6 2.3 17 230 0.07 0.4 2.45 18 230 0.07 0.2 3.8 19 150 0.3 0.6 2.21 20 150 0.3 0.4 2.813 21 150 0.3 0.2 3.8 22 150 0.13 0.6 2.161 23 150 0.13 0.4 2.596 24 150 0.13 0.2 3.711 25 150 0.07 0.6 3 26 150 0.07 0.4 3.4 27 150 0.07 0.2 3.6 2.2 artificial neural network (ann)model the input layer of ann in this work has three neurons in terms of the three process parameters and one neuron in terms of surface roughness in the output layer. different networks with different numbers of hidden layers and neurons in the hidden layer were constructed and verified to find the best network architecture; various training algorithms were utilized (gradient descent, newton method, conjugate gradient, quasinewton, and levenberg-marquardt); log sigmoid transfer functions in the hidden layer and output layer were modified and the generalization potential of the various networks was observed and eventually, the optimum network was chosen with best performance (minimum mse) to precede. the configuration of the ann is indicated as 3-40-1, consisting of three input neurons; the hidden layer is composed of forty neurons, and the output layer composed of one output neuron, as shown in figure 3. after designing and examining several networks that differ in their structure, transfer mechanism, training algorithm, etc. the number of neurons in the hidden layer is calculated by the trial-and-error process. a fig. 3. neural network schematic diagram for ra. cutting speed feed rate depth of cut   roughness artificial network osamah f. abdulateef al-khwarizmi engineering journal, vol. 17, no. 2, p.p. 817 (2021)     12 training of an ann represents an essential task in the design of an estimation model. the reliability of the forecast relies on how well it has been trained. in the work, the training of the neural network was done utilizing a “feed-forward back-propagation algorithm”. two levels of data flow are carried out by the network. the input data is first spread from the input to the output layers and generates an output as a result. then, the error signals arising from the disparity between the expected values of the networks and the real values are propagated back to the previous layers from the output layer to change their weights consequently. the weights upgrade continues till the objective of network error is achieved. the number of neurons in the hidden layer is deliberately selected to begin with five neurons, and the hidden neurons are progressively added to the hidden layer. until there is no substantial advance in network output, the addition of hidden neurons continues. in terms of network training, the network performance was assessed by mean square error (mse) between the predicted and the experimental values for each output node. the feedback from that processing is called the "average error" or "performance". since the average error is reached or below the needed target, the neural network stops training and is thus, ready to be confirmed. matlab is utilized to train the network architecture that are produced for surface roughness estimation. the performance plot of the trained ann model is shown in figure 4. the best confirmation performance (mse) of the ann is identified as 0.00006497 which can be regarded as highly acceptable. the 27 patterns input-output dataset was split randomly into three categories: the training dataset consists of 50% of the data, the test dataset consists of 25% of the data, and the validation consists of 25% of the data. for ann modeling of surface roughness, there are 13 training patterns considered. after training, the weights are frozen and the model is examined for confirmation. the network is confirmed in this work concerning the agreement with experimental outcomes. fig. 4. performance graph of the neural network after training. 3. results and discussions 3.1 experimental analysis the experiment plan is designed to determine the impact of feed rate, cutting speed, and cutting depth on surface roughness ra. this is observed in figure 5 where the surface roughness increases when the cutting speed increases from 150 rpm to 350 rpm. the above pattern of rising the surface roughness with an increase in cutting speed is due to that the rate of heat transmitted to the surrounding from the machining area may be high. therefore, the machining zone accumulates less heat. it is observed in figure 5 that as the feed rate increase from 0.07 mm/rev to 0. 3 mm/rev, the surface roughness steadily rising, due to the higher friction between cutting tool and work material as a result of greater cross-sectional area in the deformation region [19]. and it is also noted in the main impact plot in fig. 5 that the surface roughness decreases as the cutting depth increases from 0.2 mm to 0.6 mm which is in agreement with prasad et al. [19]. this can be assigned to the fact that a rise in cutting depth allows the temperature to increase due to an increase in frictional heat due to further contact between the working material and tool. higher cutting temperatures, therefore, contribute to thermal softening of the working material, which leads less roughness of the metal [19]. consequently, figure 5 and table 2 show that machining with a cutting speed of 355 rpm with a feed rate of 0.07 mm/rev and a cutting depth of 0.4 mm achieved lower surface roughness. osamah f. abdulateef al-khwarizmi engineering journal, vol. 17, no. 2, p.p. 817 (2021)     13 fig. 5. main effect plots of ra. 3.2 artificial neural network analysis the estimated values are obtained and error is determined for each data set as shown in table 3. the estimated average percentage error is 3.64 %, indicating that the accuracy of the forecast is around 96 %. figure 6 shows the plot of estimated surface roughness for different test cutting conditions utilizing the neural network and actual surface roughness. from the graphs, it is clear that for each of the output parameters, the suggested model can estimate values that are almost quite similar to experimental observations. the results show that the ann model can be easily used to predict surface roughness and thus, assists in the optimal choice of process parameters (v, f, d) for the planning of the cutting process and optimization of cutting parameters in turning dss by uncoated carbide insert tool, which is agreed with lavanya et al. [8]. osamah f. abdulateef al-khwarizmi engineering journal, vol. 17, no. 2, p.p. 817 (2021)     14 table 3, experimental and estimated surface roughness comparison exp. no. cutting speed (v) rev/min feed rate (f) mm/min cutting depth (d) mm roughness (experimental) µm roughness (ann) µm error % 1 355 0.3 0.6 2.577 2.66 3.22 2 355 0.3 0.4 2.789 2.70 3.19 3 355 0.3 0.2 2.89 2.97 2.76 4 355 0.13 0.6 2.376 2.24 5.70 5 355 0.13 0.4 2.949 2.93 0.64 6 355 0.13 0.2 2.819 2.99 6.06 7 355 0.07 0.6 2.14 1.97 7.94 8 355 0.07 0.4 1.7545 1.83 4.3 9 355 0.07 0.2 3.647 3.53 3.20 10 230 0.3 0.6 2.464 2.49 1.05 11 230 0.3 0.4 3.216 3.05 5.16 12 230 0.3 0.2 3.53 3.73 5.66 13 230 0.13 0.6 2.714 2.63 3.09 14 230 0.13 0.4 2.975 3.08 3.52 15 230 0.13 0.2 3.096 3.19 3.03 16 230 0.07 0.6 2.3 2.40 4.34 17 230 0.07 0.4 2.45 2.38 2.94 18 230 0.07 0.2 3.8 3.64 4.21 19 150 0.3 0.6 2.21 2.35 6.33 20 150 0.3 0.4 2.813 2.76 1.88 21 150 0.3 0.2 3.8 3.67 3.42 22 150 0.13 0.6 2.161 2.21 2.26 23 150 0.13 0.4 2.596 2.72 4.77 24 150 0.13 0.2 3.711 3.71 0.02 25 150 0.07 0.6 3 2.83 6.00 26 150 0.07 0.4 3.4 3.28 3.52 27 150 0.07 0.2 3.6 3.61 0.27 fig. 6. experimental and estimated surface roughness comparison at different cutting conditions. osamah f. abdulateef al-khwarizmi engineering journal, vol. 17, no. 2, p.p. 817 (2021)     15 4. conclusions in the present study, the ann model has been designed for surface roughness prediction in turning of dss by utilizing the experimental results. the outcomes of the current work are outlined in the following: machining at a cutting speed of 355 rpm with a feed rate of 0.07 mm/rev and a cutting depth of 0.4 mm has been found to achieve lower surface roughness. an increase in the cutting speed and feed rate increases the surface roughness, while an increase in the depth of cut reduces the surface roughness. the expected values obtained from ann are similar to those obtained from experimental values. the outcome of the prediction is advantageous with a 3.64% average error, which means the neural network is capable of predicting up to 96% accurate surface roughness. it is also noted that ann is a better model considering its speed, ease, and ability to learn from examples. it does not need more experimental investigation. 5. references [1] j. z. zhang, j. c. chen, and e. d. kirby, “surface roughness optimization in an endmilling operation using the taguchi design method,” journal of materials processing technology, vol. 184, no. 1-3, pp. 233-239, 2007. https://doi.org/10.1016/j.jmatprotec.2006.11. 029 [2] kahraman, and a. sagbas, “an investigation of the effect of heat treatment on surface roughness in machining by using statistical analysis,” iranian journal of science & technology, transaction b: engineering, vol. 34, no. b5, pp. 591-595, 2010. 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[4] m. nalbant, h. gokkaya, and i. toktas, “comparison of regression and artificial neural network models for surface roughness prediction with the cutting parameters in cnc turning,” modeling and simulation in engineering, vol. 2007, pp. 1-14, 2007. https://doi.org/10.1155/2007/92717 [5] k. palanikumar, and r. karthikeyan, “optimal machining conditions for turning of particulate metal matrix composites using taguchi and response surface methodologies,” machining science and technology: an international journal, vol.10, no. 4, pp. 417-433, 2007. https://doi.org/10.1080/10910340600996068 [6] a. javidi, u. rieger, and w. eichlseder, “the effect of machining on the surface integrity and fatigue life,” international journal of fatigue, vol. 30, no. 10-11, pp. 2050-2055, 2008.  https://doi.org/10.1016/j.ijfatigue.2008.01.00 5 [7] h. dave, l. patel, and h. raval, “effect of machining conditions on mrr and surface roughness during cnc turning of different materials using tin coated cutting toolsa taguchi approach”, international journal of industrial engineering computations, vol. 3, no. 5, pp. 925-930, 2012. 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[11] b. das, r. n. rai, , and s.c. saha, “ surface quality optimization of al-5cu alloy using utility theory coupled with the taguchi method,” advances in applied physical and chemical sciences-a sustainable approach, vol. 2015, pp. 40-45, 2015. [12] m. gupta, and s. kumar, “ investigation of surface roughness and mrr for turning udgfrp using pca and taguchi method,” engineering science and technology, an international journal, vol. 18, no. 1, pp. 7081, 2015. https://doi.org/10.1016/j.jestch.2014.09.006 osamah f. abdulateef al-khwarizmi engineering journal, vol. 17, no. 2, p.p. 817 (2021)     16 [13] p. sonali, and a. m. mohanty, “ performance analysis of surface roughness in al alloy using different cutting parameters,” international journal of multidisciplinary research and development, vol. 3, no. 4, pp. 1-4, 2016. [14] s. dahbi, l. ezzine, and h.e.l. moussami, “modeling of cutting performances in turning process using artificial neural networks,” international journal of engineering business management, vol. 9, pp. 1-13, 2017. https://doi.org/10.1177%2f18479790177189 88 [15] k. pawan and j. p. misra, “a surface roughness predictive model for dss longitudinal turning operation,” chapter 25 in daaam international scientific book, 2018, pp.285-296. [16] arjun joshy, royson dsouza, veerakumar muthirulan1, and krishnamurthy h. sachidananda, “experimental analysis on the turning of aluminum alloy 7075 based on taguchi method and artificial neural network,” journal européen des systèmes automatisés, vol. 52, no. 5, pp. 429-437, 2019. https://doi.org/10.18280/jesa.520501 [17] r. suresh, l. shivaramu, n.g. siddesh kumar, t.n. srikantha dath, “effect of process parameters on cutting forces and surface roughness in machining of dss 2205 using taguchi’s approach,” applied mechanics and materials, vol. 895, pp. 2631, 2019. https://doi.org/10.4028/www.scientific.net/a mm.895.26 [18] ahmed a. elsadek, ahmed m. gaafer, and s.s. mohamed, “surface roughness prediction in hard-turning with ann and rsm,” journal of the egyptian society of tribology, vol. 17, no. 2, pp. 13-22, 2020. [19] m. v. r. d. prasad, yelamanchili sravya, and karri sai tejaswi, “study of the influence of process parameters on surface roughness when inconel 718 is dry turned using cbn cutting tool by artificial neural network approach,” international journal of materials, mechanics and manufacturing, vol. 2, no. 4, pp. 335-338, 2014.  )2021( 817 صفحة ،2العدد ،17المجلد الهندسية الخوارزمي جلةم اسامة فاضل عبد اللطيف 17 الخراطة عملية بعد) dss( للصدأ المقاوم الفوالذ سطح بخشونة التنبؤ أسامة فاضل عبداللطيف بغدادقسم هندسة التصنيع المؤتمت/ كلية الهندسة الخوارزمي/ جامعة drosamah@kecbu.uobaghdad.edu.iq : البريد اإللكتروني الخالصة الخلف االصطناعية العصبية الشبكة نموذج تصميم تم الفوالذ سطح بخشونة للتنبؤ matlab neural network toolbox باستخدام يلالنتشار القطع وسرعة) f( التغذية معدل هي اإلدخال تغيراتم كانت. مصقول غير كربيد قطع نوع أداة باستخدام ة المتعامد بعد الخراطة الوجهين على للصدأ المقاوم )v (القطع وعمق )d (العملية من لكل تصميم طريقة باستخدام). ra( السطح خشونة هو اإلخراج متغير كان بينما ، ann)( توقعال ونموذج التجارب taguchi بنية على الحصول تم ، التجريبية ann تدريب خوارزمية مع مثالية levenberg-marquardt .بنية باستخدام حدودي بحث إجراء تم ann توسيعها ويمكن االستخدامات متعددة أداة هي ann أن إلى تحقيقها تم التي نتائج ال تشير. السطح خشونة على تحول متغير كل تأثير عن لإلبالغ المحّسنة .المختلفة المعادن قطع لعمليات أكبر ثقةو بسهولة this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 20, no. 3, september (2024), pp. 36-50 design and implementation of multi-configuration rolling machine f.f. mustafa*, s.q. al-musawi**, hussain a. mahdi***, k. n. salloomi****, s.d. reda*****, ahmed al-ashaab****** and adel al-jumaily******* *,**,****automated manufacturing department, al-khwarizmi college of engineering, university of baghdad, baghdad 10071, iraq ***maintenance board manager, ministry of oil, midland refinery company, baghdad, iraq *****general directorate of electrical power production, ministry of electricity baghdad, iraq ******manufacturing department, school of aerospace, transport & manufacturing, cranfield university, cranfield, bedford, uk *******faculty of engineering, university of technology brunei, brunei *email: dr.faiz@kecbu.uobaghdad.edu.iq (corresponding author) **email: sarahmsc136@gmail.com ***email: eng.hussainalbawi@gmail.com ****email: kareem@kecbu.uobaghdad.edu.iq *****email: dr.eng.sarmad@gmail.com ******email: a.al-ashaab@cranfield.ac.uk *******email: adel.aljumaily@gmail.com (received 6 november 2023; revised 2 april 2024; accepted 26 june 2024; published 1 september 2024) https://doi.org/10.22153/kej.2024.06.001 abstract for decades, metal corrugated sheets have usually been manufactured using conventional roll-forming machines with lower and upper rollers or a die and a press as the main shaping elements. however, these machines and their related processes present economic disadvantages because of additional expenses required to improve and manage forming tools. to overcome these drawbacks, reconfigurable machines, such as dedicated and flexible manufacturing systems, were used as alternatives; they possess high flexibility for accomplishing forming processes. reconfigurable machines are designed around a particular family of manufactured outcomes, allowing for high system flexibility. in light of the latest developments in reconfigurable machine design, this study proposes a new sheet metal forming roller called the discrete multi disk roller (mdr) as an alternative to the traditional roller design. unlike existing processes, the mdr minimises production costs associated with material loss and effectively decreases forming errors. furthermore, it utilises multi-disk as reconfigurable rollers. the technique and applicable procedure of the mdr are described, and wavy sheets with different dimensions and shapes are formed to verify the applicability of the reconfigurable roller, a critical component in the forming process. thirteen parts with different configuration profiles were produced using the proposed mdr machine. keywords: machine design; reconfigurable machine; discrete multi-disk roller; reconfigurable manufacturing 1. introduction mediumand high-volume parts are currently produced by applying two conventional manufacturing techniques: dedicated manufacturing systems (dmss) and flexible manufacturing systems (fmss). dmss are costeffective for large production volumes and extended production durations, so they are intentionally used to produce a specific, unchanging part [1]. conversely, fmss are economical when the manufacturing quantities are limited, and large varieties of parts are produced, allowing for many design modifications to be mailto:dr.faiz@kecbu.uobaghdad.edu.iq mailto:sarahmsc136@gmail.com mailto:eng.hussainalbawi@gmail.com mailto:dr.eng.sarmad@gmail.com mailto:a.al-ashaab@cranfield.ac.uk mailto:adel.aljumaily@gmail.com https://doi.org/10.22153/kej.2024.06.001 f.f. mustafa al-khwarizmi engineering journal, vol. 20, no.3, p.p. 3650 (2024) 37 made during production [2]. nonetheless, the fast changes in market demands have rendered traditional dmss impractical for many industrial applications, leading to a broader adoption of fmss. however, the inability to achieve the same level of efficiency and robustness as in dmss and the high resource wastage during production procedures have made fmss uneconomical in many situations [3]. in response to these challenges, a novel approach to customised manufacturing was developed named reconfigurable manufacturing systems (rmss). the major advantage of this new technique is the customised flexibility to produce a ‘part family’ of products at lower investment costs than fmss [1]. typically, rmss incorporates conventional flexible machines and a new type of machine called the reconfigurable machine (rm) into its production line. rms are designed around a specific part family of products and enable substantial changes in their structure. the idea behind rms is to allow changes in machine configuration according to production requirements. rms introduced a new methodology to bridge the gap between the high flexibility and high cost of totally flexible machines and the low flexibility and low cost of fully dedicated machines [1]. in addition, these systems are designed to accommodate a specific range of production requirements (i.e. product mix and volumes). rmss are categorised according to their functional flexibility. they may be suitable for certain production requirements or economically replaced with a new set of production necessities. with the flexibility of combining the advantages of dmss and fmss such as production requirement customisation, resource minimisation and flexibility in their design, rmss are considered an economical and robust solution for many industrial applications [4,5,6]. several studies have focused on the rolling process using a dedicated roller die. scientific literature on the reconfigurable rolling process (rrp) using a pin or punch-type tooling is limited. yoon et al. [7,8,9,10] proposed a new sheet metal forming process named the flexibly reconfigurable roll forming (frrf) as an alternative to existing processes. unlike the conventional forming processes, frrf can lower the production expenses resulting from material loss and minimise forming errors. moreover, it uses a smaller apparatus, adjustable punches and upper and lower reconfigurable rollers to manufacture full-size blanks in the longitudinal direction, similar to the regular roll forming process. wang et al. [11,12] designed a novel forming process for 3d surface parts that combines rolling with multi-point forming technology. this process employs a set of two forming rolls. the roll gap of the forming rolls has a non-regular distribution which, when controlled, leads to a residual stress pattern in the sheet metal that generates a 3d deformation. to advance flexible manufacturing, cai et al. [13] and park et al. [14] developed a highly flexible forming technology that can efficiently produce 3d sheet metal sections with multiple curvatures. this process uses a forming tool consisting of an upper flexible roll and two lower flexible rolls in which the shape of the flexible roll can be changed vertically. however, reconfigurable flexible forming systems still experience difficulties, such as problems related to positioning and locking pins and issues of uneven surface effects caused by small, discrete pins. this study proposes a new rolling machine design is to overcome the abovementioned drawbacks of pin-type tooling. the rolling method utilised here differs from the previous methods. it produces variable wavy shapes in a single roller stand without the need for multiple rollers. the process is achieved by adjusting the rolls constructed from distinct disks with varying diameters and thicknesses. different groupings and arrangements of these disks result in a variety of waveforms and dimensions. 2. invented multi-disk roller (mdr) in the shape-forming process, two rollers are used to press a workpiece, deforming it until it reaches the desired shape and geometry that is machined onto the outer surface of both rollers. figure 1 shows a schematic of a shape-rolling machine that produces corrugated plates characterised by amplitude and wavelength. a restriction of machined rollers (mrs) is that each roller set is dedicated to producing a specific shape and dimension, requiring a replacement in case of wear or failure. the proposed roller (upper and lower) suggests discretising the waveform by chopping the roller along its length into disks. in addition to other waveforms and dimensions that can be approximated using these disks, the required waveform can be obtained by synthesising these disks. figure 2 shows the transformation from mr to mdr. the mdr overcomes the limitations of mr because of the manipulative susceptibility of disks and the recyclability of the configured disks. in the event of wear and failure, f.f. mustafa al-khwarizmi engineering journal, vol. 20, no.3, p.p. 3650 (2024) 38 the disks can be reproduced by refining larger disks into smaller ones, allowing for continued use in operational processes. fig. 1. production of a corrugated plate characterised by amplitude and wavelength fig. 2. transformation from machined rollers (mrs) to multi-disk rollers (mdrs) 3. design of mdr roller disk dimensions (thickness and diameter) are crucial in the forming process. a thinner disk allows for better approximation of the waveform profile, but high-strength material is needed for disk manufacturing. disk diameter also depends on thickness because they both determine the geometry the disk will generate. the rollers with multiple disks are multi-point forming tools whose geometric configuration is illustrated in figure 3. each disk has a uniform thickness of 1 mm, and the disk diameter is determined using a sine curve equation based on the roller’s properties and dimensions. referring to figure 3, n l n uf rtrh  …(1) ) 2 sin( 2 )( 2 l nst xy h r fn u   …(2) ) 2 sin( 2 )( 2 l nst xy h r fn l   …(3) where l is the wavelength, n is the disk number, s is the disk thickness, t is the workpiece thickness (plate), x is the dimension along roller length, y(x) is the deformed shape describing function and hf is the distance between lower roller centre line and upper roller centre line. n u r and n l r are the upper and lower roller disk radii, respectively. a is the amplitude of the sine wave defined as follows: ) 2 sin()( l ns axy   , where n = 1, 2,3,… solving these equations for (hf = 120 mm, l = 40 mm, a = 10 mm, t = 0.5 mm, s=1 mm and n (1 to 40)) gives the results shown in table 1. the disk arrangement on each roller is illustrated in figure 4. the top roller starts ascending to configure the upper edge of the metal, and the lower roller starts descending to configure the lower edge of the metal. f.f. mustafa al-khwarizmi engineering journal, vol. 20, no.3, p.p. 3650 (2024) 39 fig. 3. design of mdr table 1. calculated disk radii fig. 4. disk arrangement: (a) upper roller and (b) lower roller 4. general configuration of mdr the rollers synthesised from disks were arranged in a sequence, so they formed a sine wave curve with a specific dimension. each roller has 240 disks, distributed over six waves, with each wave comprising 40 disks. one dimension of a sine curve is the wavelength which is calculated from the number of disks and their thicknesses. in this case, the wavelength of the reconfigured profile is l = 40 mm. another dimension is the amplitude (a), the absolute value of the maximum displacement from a zero value during one oscillation period. the measurements involve diameters, so the amplitude can be determined as shown in figure 5. d10 represents the maximum disk radius, and d30 represents the minimum disk radius. where d10/2 = 69.75 and d30/2 = 49.75 amplitude = ((d10/2) – (d30/2)) / 2 = 10. disk number lower roller (mm) upper roller (mm) disk number lower roller (mm) upper roller (mm) d1 58.19 61.31 d21 61.31 58.19 d2 56.66 62.84 d22 62.84 56.66 d3 55.21 64.29 d23 64.29 55.21 d4 53.87 65.63 d24 65.63 53.87 d5 52.68 66.82 d25 66.82 52.68 d6 51.66 67.84 d26 67.84 51.66 d7 50.84 68.66 d27 68.66 50.84 d8 50.24 69.26 d28 69.26 50.24 d9 49.87 69.63 d29 69.63 49.87 d10 49.75 69.75 d30 69.75 49.75 d11 49.87 69.63 d31 69.63 49.87 d12 50.24 69.26 d32 69.26 50.24 d13 50.84 68.66 d33 68.66 50.84 d14 51.66 67.84 d34 67.84 51.66 d15 52.68 66.82 d35 66.82 52.68 d16 53.87 65.63 d36 65.63 53.87 d17 55.21 64.29 d37 64.29 55.21 d18 56.66 62.84 d38 62.84 56.66 d19 58.19 61.31 d39 61.31 58.19 d20 59.75 59.75 d40 59.75 59.75 f.f. mustafa al-khwarizmi engineering journal, vol. 20, no.3, p.p. 3650 (2024) 40 fig. 5. calculated sine curve amplitude 5. mdr apparatus and its implementation st35 steel alloy was selected for the disks because of its cost-effectiveness and suitability for plasma cutting processing that offers high cutting precision and quality edge cutting essential for achieving the desired shape. all cutting edges underwent grinding to produce a smooth contact surface which touches one another during disk assembly. the disks were then tightly secured along a shaft with a length of 530 mm and a diameter or 25 mm to prevent movement or separation during the forming process, as shown in figure 6. the shaft holds a pillow block bearing that is composed of mounted units and is designed to provide shaft support with the mounting surface parallel to the shaft axis. the bolt holes in the bearing are usually slotted for adjustment during mounting. the frame of the developed machine body is shown in figure 7a. it consists of a ground base with two guide plates mounted on each side. two upper mounting frames, as shown in figure 7b, are attached to the top portion of the machine body with a top adjustment bolt. these frames are designed to provide vertical adjustment for the upper roller and carry and support the bearing guide. each bearing guide is attached to the frame by bolts and nuts through aligned holes. the lower mounting frame system is similar to the upper one, except that the coupling nut is replaced by a bolt. a mechanism is used to set the height of the upper roller and adjust the distance between the two rollers, thereby controlling the passage of the metal during the forming process, as shown in figure 8. a set screw is used to hold the bearing by forcing it through the bolt hole of the bearing, which is attached to the hand wheel to turn its movement. a lock nut is used to secure the screw onto the bearing, preventing it from loosening. in addition, a flat washer is placed beneath the bolt hole to provide a smooth rotation of the screw. the system used to control the pressure applied by the upper roller consists of a hex head bolt to move up and down through a coupling nut, providing a screw path. this mechanism converts rotational movement into linear movement, applying a torque to the roller. as the shaft bolt is rotated relative to the stationary threads (coupling nut), the bolt travels along its axis relative to the surrounding medium. an electric motor gearbox system (1/2 hp with a speed of 50 rpm) with a gear train was used to transmit rotary motion. the gear train consists of spur gears to transmit power from one shaft to another (one gear on each shaft). the nature of the gear train depends on the relative position of the axes of the shafts (two roller shafts and input drive shaft) on which the gears are mounted. each gear is mounted on a keyed shaft with a round bore and a set screw, ensuring that the gears are fixed relative to each other. the outside diameter of the roller’s gears is 120 mm with 40 teeth, and the outside diameter of the gearbox is 60 mm with 20 teeth, reducing speed and increasing load capacity. the complete machine frame with rollers and its drive system is shown in figure 9. straightening guides were used as an accessory tool and mounted on the machine frame, as shown in figure 10. the guide consists of a right-angle, two-piece part mounted on a strip with a bolt and nut to allow for position adjustments to achieve the required spacing smoothly and easily. f.f. mustafa al-khwarizmi engineering journal, vol. 20, no.3, p.p. 3650 (2024) 41 disks insertion and arranging disks clamping fig. 6. roller configuration process fig. 7. (a) machine frame, (b) mounted frame fig. 8. roller adjustment mechanism fig. 9. full machine frame fig. 10. sheet guide and handle 6. results and discussion the results obtained focus on the profiles produced, and they are discussed together with the design considerations in the roll-forming machine, the reconfigurable mechanism, the geometry of the rollers together with their effect on formed profiles and the benefits of using these rollers. two different formed profiles are considered in this study: corrugated and multi-dimensional sine curved profiles. in both cases, the reconfiguration is achieved by rearranging the sequence of disks. various materials with different thicknesses are used for the output-formed sheets, as indicated in table 2. in all cases, the amplitude value is calculated using d10 and d30, as explained earlier. aball dimensions in mm f.f. mustafa al-khwarizmi engineering journal, vol. 20, no.3, p.p. 3650 (2024) 42 table 2 formed profiles, materials and their dimensions 6.1 corrugated profiles corrugated profiles are obtained by changing the disk arrangement, which is accomplished by adding and subtracting disks, as detailed in table 3, to match the die shape profile. table 3 shows the different roller configurations, produced corrugation profiles, their die shape and measured dimensions. the disk arrangement used to produce these profiles is illustrated in figure 11. the produced corrugated shapes include curves and straight lines. to form a straight line, a sequence of the same disk diameters is required; each disk repeated two times for each wave results in a maximum line length of 6 mm. however, this length is insufficient compared with a standard profile and does not produce a clear formed profile. this limits the number of repetitions, where the maximum wave number reached is only two waves. the dimensional accuracy of the finished part is affected by the springback property of the shaped metal which in turn causes elastic recovery of deformed parts. as seen in table 3, the measurements are greater than the die shape. the final form of a part is changed by springback, making it difficult to produce the desired part geometry. controlling the springback in sheet metal forming is a crucial manufacturing problem. unless the springback is accurately estimated in advance, a sheet of metal that has been accurately corrugated, shall readjust itself, preventing the proper shape of the corrugations from being retained. springback can be eliminated by overforming. the sheet metal is overformed to a smaller dimension than needed. the recovery of the material from springback results in a calculated increase in dimensions. this increase makes the recovered dimensions match the original design. parameters such as material property, sheet thickness and tooling geometry affect the springback behaviour. fig. 11. disk sequence of corrugated profiles material type material thickness (mm) measured amplitude [a] (mm) measured wavelength [l] (mm) number of passes formed profile steel 0.5 9.9 40 44 steel 0.8 9.8 40 57 steel 1 9.86 40 25 lead 1 10.4 40 6 zinc 0.3 9.3 40 7 f.f. mustafa al-khwarizmi engineering journal, vol. 20, no.3, p.p. 3650 (2024) 43 table 3 corrugated profiles and their dimensions roller configuration top configuration of roller desired dimensions (mm) measured dimensions (mm) formed profile 1 2 3 4 nevertheless, some shape defects, like edge waves, bending in the longitudinal and vertical planes, and twisting, can occur during the rolling process, as shown in figure 12. to prevent these defects, the mechanisms that cause them should be examined. shape orientation, which is the part’s position relative to the roll axis, is an important element of roll design. it affects part quality, causing shape defects and limiting the effectiveness of roll-forming passes, making it difficult to achieve the desired dimensional accuracy. therefore, accessory tooling is necessary to mount the part on horizontal axes between driven roll stages. when the length sheet is fed through a roll-forming machine, a guiding device is used to ensure the part’s sides are properly aligned as it progresses from pass to pass. this tooling process eliminates defects. fig. 12. defects of rolled profiles f.f. mustafa al-khwarizmi engineering journal, vol. 20, no.3, p.p. 3650 (2024) 44 6.2 multi-dimensional sine wave curve profiles multi-dimensional sine wave curve profiles are divided into the wavelength curve changes (amplitude) and the length curve changes (wavelength). 6.2.1 multi-wavelength sine wave curve profiles in this type, the wavelength is changed whilst maintaining the same value of the amplitude (10 mm), with disks 10 and 30 remaining unchanged. this process requires reducing the number of disks used to get the specific dimensions. sine wave curve is symmetrical to the upper and lower parts of the waveform, and each half is symmetrical so that the amount of any disk reduction must be the same for each quarter. in other words, the amount of reduction is multiplied by four. table 3 shows the derived wavelength which is expressed as follows: – (the amount of disks reduced from one quarter*4) …(4) where defines the wave’s full length that includes 40 disks. fine wavelength can be produced as disk reduction increases. the smaller the set of disks, the finer the curve, so more disks are needed to make a smooth surface profile. the maximum number of disks reduction that can be obtained is five disks. tables 4 and 5 show the dimensions of profiles produced and disks removed to obtain the specific dimensions for sheet thicknesses of 0.5 mm and 0.8 mm, respectively. table 4. multi-sine wave curve profiles and their dimensions for sheet thickness of 0.5 mm wavelength [l] (mm) amplitude [a] (mm) number of passes disk removed formed profile 36 8.5 30 d2-d19-d22-d39 32 7 38 d2-d3-d18-d19-d22d23-d38-d39 28 5.7 25 d2-d3-d4-d17-d18d19-d22-d23-d24d37-d38-d39 24 6 36 d2-d3-d4-d5-d16d17-d18-d19-d22d23-d24-d25-d36d37-d38-d39 24 6.16 48 d3-d5-d7-d9-d11d13-d15-d17-d23d25-d27-d29-d31d33-d35-d37 20 5.76 43 d1-d3-d5-d7-d9d11-d13-d15-d17d19-d21-d23-d25d27-d29-d31-d33d35-d37-d39 f.f. mustafa al-khwarizmi engineering journal, vol. 20, no.3, p.p. 3650 (2024) 45 table 5. multi-sine wave curve profiles and dimensions for sheet thickness of 0.8 mm wavelength [l] (mm) amplitude [a] (mm) number of passes disk removed formed profile 36 8 35 d2-d19-d22-d39 32 6.8 45 d2-d3-d18-d19d22-d23-d38-d39 28 6.1 35 d2-d3-d4-d17-d18d19-d22-d23-d24d37-d38-d39 24 6.7 54 d2-d3-d4-d5-d16d17-d18-d19-d22d23-d24-d25-d36d37-d38-d39 24 5.59 56 d3-d5-d7-d9-d11d13-d15-d17-d23d25-d27-d29-d31d33-d35-d37 20 6.15 48 d1-d3-d5-d7-d9-d11d13-d15-d17-d19d21-d23-d25-d27d29-d31-d33-d35d37-d39 6.2.2 multi-amplitude sine wave curve profiles in this group, the wavelength is fixed whilst the amplitude is changed by removing disks in the peaks and compensating with a certain number of disks to maintain wavelength. tables 6 and 7 list the profiles produced with the disk arrangement for two different sheet metal thicknesses. figure 13 shows the roller configurations for each profile of changed amplitude. the number of waves is reduced because the compensated disks are taken from the other waves to maintain the same wavelength. disks are set to clamp at their ends with a heavy hex nut used with a threaded insert which is fixed with a dimple drilled into the shaft. the set of disks is 240 mm in length. the reduction of disks to form the required configuration changes the position of the clamped nut; therefore, washers are used to compensate the removed disks to maintain these clamps at their positions for all formed profiles, as seen in figure 14. in this group, the produced profiles are free of any shape defects, unlike the corrugated profiles. this improvement is attributed to the sheet metal guide discussed earlier. the formed profiles include changes in amplitude and wavelength. the wavelength dimension of all produced profiles is identical with the die-shape wavelength values, but the amplitude dimension is not identical within the die-shape amplitude. the amplitude of the profile is measured by the gap distance available between rollers. two techniques are followed to remove disks. to reach the die shape wavelength, the disks are removed in ascending direction, maintaining disks (1, 20, 21 and 40) at their position. these disks are considered the start and end points of the curve, and the disks between them are removed sequentially. this configuration is applied to f.f. mustafa al-khwarizmi engineering journal, vol. 20, no.3, p.p. 3650 (2024) 46 wavelengths ranging (36–24) mm. figure 15 shows the roller configuration results from this technique, and figure 14 shows the clearance generated between rollers. the other wavelength values take the same shape but with varied sizes according to the part length. the clearance configuration between rollers shown in figure 16 is the same for all formed profiles. as the number of removed disks increases, the difference between the diameters of the remaining disks grows, leading to a greater number of passes over a considerable area. this technique results in a high compressional stress on the edges of the disks, causing them to fold. therefore, another technique is applied to the wavelength (24). disks (1-20-21-40) remain at their position where the even-numbered disks are removed, and the sequence of disks remains in the roller (e.g. d1-d3-d5-d7-d9-d11-d13-d15-d17d19…). this arrangement is applied to wavelengths 24 and 20. for the 20 mm wavelength, the number of disks that should be removed is 20 disks. following this technique, the disks removed were 10 and 30 to minimise the difference between the disks. therefore, the die shape amplitude is calculated as the difference between disk 9 (which is the same diameter as disk 11) and disk 29 (which is the same diameter as disk 31). this configuration mechanism produced some shape defects, as shown in table 8. high concentrations of stresses and strain are developed at sharp peaks caused by disk reduction. reduction of the peak area makes it weaker, and the material starts cracking. fracturing starts at these sharp peaks, and the reduction in the roller disk makes it brittle, and the plastic deformation in the sheet to exceeds the ductility of the metal, leading to rupture and tearing of the sheet metal. as seen in table 8, necking develops after some strain, causing thinning and stretching. as previously mentioned, deformation becomes concentrated in the peak area, and the necking further intensifies the deformation, causing the part to stretch and eventually fracture. the capability of the machine to handle the amplitude of the profile is restricted by certain design attributes, such as the roller gap control. a key target of roll table 6. formed profiles of 0.5 mm sheet thickness and their dimensions die shape amplitude measured amplitude number of waves compensated disks number of compensated disks formed profile 9.88 9.3 4 d9-d11-d29d31 one for each peak 8.91 10.25 2 d8-d12-d28d32 three for each peak table 7. formed profiles of 0.8mm sheet thickness and their dimensions die shape amplitude measured amplitude number of waves compensated disks number of compensated disks formed profile 9.88 9.3 4 d9-d11-d29d31 one for each peak 8.91 9.6 2 d8-d12-d28d32 three for each peak f.f. mustafa al-khwarizmi engineering journal, vol. 20, no.3, p.p. 3650 (2024) 47 fig. 13. roller configuration of fig. 14. clamped configuration reconfigured amplitude of sine wave curve for a = 9.88 (a) and a = 8.91 (b) fig. 15. roller configuration fig 16. gap between rollers pass design is to accurately build a sequence of reductions to minimise the relative differences in shape changes between different areas, thereby avoiding material imperfections. improper reductions of the product can cause warping or cracking of the material, as presented in the profile. another technique for forming the part is adopted in the next section. table 8. shape defects of formed profiles wavelength of profile profile thickness of 0.8 mm profile thickness of 0.5 mm 24 20 6.3 variable wave number per pass a sequential forming process is used to produce accurate dimensional parts without serious defects. the formed part is constructed firstly by partitioning the die with only two waves, followed by the cumulative addition of other waves. for steel-type material, the number of passes required for the production of a twowave formed sheet is 15 and 22 for four waves, which ensures the efficiency of this procedure. the formed part closely matches the die shape’s wavelength and achieves an amplitude value that is reasonably close to the desired value. the work hardening and strength of the formed part are effective parameters that facilitate the production of the wave part without failure. the produced profile is shown in figure 17, and its dimensions are shown in table 9. for lead-type material, the forming process using the same roller configuration is slightly more complicated. only two waves are formed because of the penetrating lines formed on the metal surface which substantially increase the wavelength and make pulling the metal difficult and impossible. figure 18 shows the formed part of a two-wave profile and penetrating lines on the surface. f.f. mustafa al-khwarizmi engineering journal, vol. 20, no.3, p.p. 3650 (2024) 48 table 9. dimensions of formed profiles fig. 17. first stage of the formed profile consisting of two waves (a) and second stage of the formed profile consisting of four waves (b) fig. 18. formed lead sheet (a) and penetrating lines on surface (b) 7. conclusions this research aims to improve the flexibility in roll forming process and reconfigurability of the related manufacturing tools. it focuses on the novel idea of using multiple thin disks with varying diameters to compose the upper and lower rollers of the rolling/roll forming process which then converge the shape of the target sheet profile. this interesting approach of mdrs positively affects the reparation effort of the rollers in case of wear or failure. the reason is that only the replacement of single disks is necessary, thus avoiding the full reproduction of the rollers. additionally, defective disks can be recycled by machining bigger disks into smaller ones which leads to cost savings. mdrs can produce a diverse range of parts, including sine wave curves and corrugated profiles, especially with acute requirements on geometry modification. the mdr can produce 13 different parts on the same machine. the reconfigurable designs include the part scale and shape. the primary design limitation in achieving a greater variety of outputs is the number of disks used which determines the shape and dimensions of the product. this limitation can be overcome by increasing the size of the roller and using a greater number of disks, enabling the production of material type material thickness (mm) die shape amplitude (mm) die shape wavelength (mm) measured amplitude (mm) measured wavelength (mm) number of passes steel 0.5 9.88 20 9.25 (for two cycles) 8.4 (for four cycles) 20 15 (for two cycles) 22 (for four cycles) lead 3 9.88 20 8.325 (for only two cycles) 20 25 f.f. mustafa al-khwarizmi engineering journal, vol. 20, no.3, p.p. 3650 (2024) 49 multiple profile geometries. the discrete nature of the designed rollers allows for reconfiguration into multiple configurations, saving cost and time necessary to invent new tools. various products with different geometries and dimensions have been manufactured, confirming the tool’s capability. inadequate reductions in both the manufactured part and the metal guide, along with alignment issues, bring out defects such as dimensional irregularities and fractures. this study has identified solutions to avoid these defects. acknowledgements the authors would like to 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[14] park j-w, kim j, kang b-s. development on a prediction model for experimental condition of flexibly reconfigurable roll forming process. metals. 2019; 9(8):896. https://doi.org/10.3390/met9080896 https://doi.org/10.3390/met9080896 (2024) 36-50، صفحة 3، العدد20جلدمجلة الخوارزمي الهندسية الم فائز فوزي مصطفى 50 تصميم وتنفيذ ماكنة لف متعددة التكوين ، ****، كريم نعمه سلومي***، حسين علي مهدي **، سارة قاسم الموسوي * فائز فوزي مصطفى *******، عادل الجميلي ******احمد االشعب ، *****سرمد ضياء رضا قسم هندسة التصنيع المؤتمت، كلية الهندسة الخوارزمي، جامعة بغداد، بغداد ، العراق *،**،**** مدير هيئة الصيانة، وزارة النفط، شركة مصافي الوسط، بغداد، العراق *** لعراق، بغداد، االمديرية العامة إلنتاج الطاقة الكهربائية، وزارة الكهرباء ***** قسم التصنيع، كلية الطيران والنقل والتصنيع، جامعة كرانفيلد، كرانفيلد، بيدفورد، المملكة المتحدة ****** كلية الهندسة، الجامعة التكنولوجية بروناي، بروناي ******* hdad.edu.iqdr.faiz@kecbu.uobagالبريد االلكتروني:* sarahmsc136@gmail.com : البريد االلكتروني** eng.hussainalbawi@gmail.comالبريد االلكتروني:*** kareem@kecbu.uobaghdad.edu.iqالبريد االلكتروني:**** dr.eng.sarmad@gmail.comالبريد االلكتروني:***** ashaab@cranfield.ac.uk-a.al:البريد االلكتروني****** comadel.aljumaily@gmail.البريد االلكتروني:******* المستخلص علوية أو ت السفلية والباستخدام آالت تشكيل تقليدية تتضمن استخدام كل من األسطوانا غالبالعقود من الزمان، كانت الصفائح المتموجة المعدنية تُصنع فقات ن فةيتم اضاإذ عيوب، اقالب وضاغط كعناصر رئيسة للتشكيل. من الناحية االقتصادية، فأن استخدام مثل هذه اآلالت مع العمليات المتصلة بها يوجد له وأنظمة التصنيع للتغلب على مثل هذه العيوب، تم استخدام آالت قابلة للتشكيل )أنظمة التصنيع المخصصةو. ها التشكيل وادارتإضافية لتحسين أدوات ن األجزاء ائلة معينة معالمرنة( كفئة أخرى من اآلالت التي تتمتع بمرونة عالية في إنجاز عمليات التشكيل. يتم بناء اآلالت القابلة للتشكيل ببساطة حول اً جديدتصميماً ح الحالية تقتر نتيجة للتطورات األخيرة في مجال تصميم اآلالت القابلة للتشكيل ، فان الورقة البحثيةومح بمرونة عالية في نظامها. الُمنتجة وتس على عكس اص.قركبديل للتصميم الحالي لأل discrete multi disk roller (mdr)سمى األسطوانة المتعددة األقراص ال يلتشكيل الصفائح المعدنية يتضمن ذلك، فضال عن تقليل التكاليف اإلنتاجية الجماعية الناجمة عن فقد المواد وتقليل األخطاء في التشكيل بفعالية. mdrالعمليات الحالية، يمكن لـ ختلفة للتحقق بأبعاد وأشكال م وتشكيل صفائح مموجة mdrقراص قابلة للتشكيل. تم وصف تقنية وإجراءات أالتصميم المقترح استخدام أقراص متعددة ك اكنة ال ة باستخدام ممن قابلية استخدام االقراص القابلة للتشكيل وهي عنصر حرج في هذه العملية التشكيلية. تم إنتاج ثالثة عشر جزًءا بتكوينات مختلف mdr. mailto:dr.faiz@kecbu.uobaghdad.edu.iq mailto:sarahmsc136@gmail.com mailto:eng.hussainalbawi@gmail.com mailto:kareem@kecbu.uobaghdad.edu.iq mailto:dr.eng.sarmad@gmail.com mailto:a.al-ashaab@cranfield.ac.uk mailto:adel.aljumaily@gmail.com this is an open access article under the cc by license. al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 19, no. 3, september, (2023) p. p. 2332 green fabrication and characterization of zinc oxide nanoparticles using eucalyptus leaves for removing acid black 210 dye from an aqueous medium ** abdelmalik milad shakorfow *zahraa a. najm najah al mhanna*** ahmed k. hassan**** mohammed a. atiya***** *,*****department of biochemical engineering/ al-khwarizmi college of engineering/ university of baghdad/ baghdad/ iraq **elmergib university / libya *** german university of technology in oman/ oman **environment and water directorate/ ministry of science and technology/ baghdad/ iraq zhraqylnjm@gmail.com: *email :corresponding author dr_eng.malik@yahoo.co.uk email:** najah.almhanna@gutech.edu.om email:*** ****email: ahmedkhh71@gmail.com atiya@kecbu.uobaghdad.edu.iqemail: ***** (3202 february 62 accepted; 2022 december 18 received) 3https://doi.org/10.22153/kej.2023.02.00 abstract this study uses an environmentally friendly and low-cost synthesis method to manufacture zinc oxide nanoparticles (zno nps) by using zinc sulfate. eucalyptus leaf extract is an effective chelating and capping agent for synthesizing zno nps. the structure, morphology, thermal behavior, chemical composition, and optical properties of zno nanoparticles were studied utilizing ft-ir, fe-sem, edax, afm, and zeta potential analysis. the fe-sem pictures confirmed that the zno nps with a size range of (22-37) nm were crystalline and spherical. two methods were used to prepare zno nps. the first method involved calcining the resulting zno nps, while the second method did not. the prepared zno nps were used as adsorbents for removing acid black 210 dye (ab210) from simulated wastewater. the removal efficiency using calcinated and uncalcinated zno nps was 57 % and 59 %, respectively. keywords: green synthesis; zno nanoparticles; adsorption process; eucalyptus; acid black 210 dye (ab210). 1. introduction in the last few decades, several industries like leather, pharmaceuticals, food, and cosmetics have grown a lot, and all of them make dye effluents. around 70% of dyes used are azo dyes, which have an aromatic ring-bonded n=n character and are pathogenic and carcinogenic. however, these dyes are poisonous and negatively impact the environment and aquatic communities. as a result, considerable attention has appeared to be focused on finding effective remediation methods for treating dye-contaminated wastewater [1]. water contaminated with dyes has been removed through adsorption, membrane separation, chemical coagulation and precipitation [1], oxidative-reductive degradation, and electrocoagulation [2][3]. despite the many methods available for removing dyes, adsorption is the preferred method and offers the best results among different dye removal processes because it can be used to remove various coloring components [4]. due to their high surface areas, the mailto:dr_eng.malik@yahoo.co.uk mailto:najah.almhanna@gutech.edu.om mailto:ahmedkhh71@gmail.com mailto:atiya@kecbu.uobaghdad.edu.iq https://doi.org/10.22153/kej.2023.02.00 zahraa a. najm al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 2332 (2023) 24 other catalysts used as adsorbents in wastewater treatment, such as activated carbon, are considered excellent. however, activated carbon is expensive, requires a long time, and is precocious to prepare. therefore, using nanomaterials prepared from lowcost and available materials is an excellent alternative to overcome problems associated with other adsorbents [4]. recently, nanotechnologies have been essential in removing environmental pollutants [1]. nanoadsorbents provide better adsorption capability than conventional adsorbents due to an increase in specific surface area and higher selectivity since the surface of the nanomaterial can be functionalized to target pollutants specifically [5]. zinc oxide nanoparticles (zno nps) are flexible semiconductors that exhibit notable optical transparency and luminous capabilities in uvvisible (uv-vis) regions and have excellent chemical and thermal stability [6]. additionally, zno nps are easy to prepare, with a high specific surface area and non-toxic nature [6]. various physical and chemical methods have been employed in zno nps preparation, like milling, vacuum sputtering, microwave-assisted techniques, chemical vapor deposition thermal breakdown, and a chemical reduction process using sodium borohydride as a reducing agent [7]. these methods involve using complex equipment, lengthy procedures, and hazardous chemicals. therefore, the biological approach is promising for resolving these problems and developing a suitable and safe way to produce nanoparticles. the biological method involves preparation technology based on plant extracts or microorganisms [7]. green synthesis using plant extract has unique advantages such as being environmentally friendly, taking less time, being more affordable, operating steadily, and, most significantly, carrying out the process without any dangerous chemicals [8]. different plant extracts, including cassia fistula, eucalyptus leaf extract [9], tea leaf extract [10], trifolium pretense, ocimum basilicum, and others, have been employed in the green synthesis of zno nps. have also been used in the production of nanoparticles [11]. the eucalyptus plant is a reliable supplier of bioactive compounds. in the green technique, terpenoids, phenols, and their organs have all been expertly utilized for manufacturing nanoparticles. also, it is a highly available plant in most countries [12]. this study focused primarily on two procedures for synthesizing zinc oxide nanoparticles (zno nps) using the extract from the eucalyptus plant; then, it was used to remove an anionic acid black 210 dye (ab210) from wastewater. 2. materials and methods 2.1 chemical and reagents cdh company's zinc sulfate hexahydrate (znso4. 7h2o) with a molecular weight of 287.54 g and a purity of >98.0%. (naoh ) was purchased from cdh company. absolute ethanol was purchased from carlo erba's company. acid black 210 (ab-210) was taken from a leather factory in baghdad, iraq. table 1 displays the chemical and physical characteristics of the ab210 dye. table 1, chemical and physical properties of acid black 210 (ab210) [13]. molecular formula c34h25k2n11o11s3 melting point 300 ℃ solublity soluble in water types of dye azo dye (n═n) chemical structure 2.2 preparation of the leaf extract the method for the synthesis was taken from [14] with slight modifications. initially, the eucalyptus leaves were picked up from the yard at baghdad university and repeatedly washed. for dust and difficult dirt removal, use distilled water. the leaves were then dried for 12 hours at 50 °c in the oven. the leaves were ground into a fine powder when thoroughly dried and became zahraa a. najm al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 2332 (2023) 25 crushable. 150 ml of deionized water was used to wet 10 g of powdered eucalyptus leaves in an erlenmeyer flask for 30 minutes while stirring at 80 °c. the resulting extract was cooled and filtered through filter paper; the filtrate was then kept at 4 °c until it was used as a reducing and capping agent to reduce zinc ions (zn+2) into zinc oxide nanoparticles (zno). 2.3 preparation of zno nps to complete the preparation of zno nps, 1.61 g of solid znso4 was added to 100 ml of deionized water and magnetically stirred at 150 rpm for 10 min. a 0.45 µm membrane filter was used to filter the solution once it had fully dissolved to get rid of contaminants. the znso4 solution was gradually added for 15 minutes at 70 °c while being continuously agitated. eucalyptus extract was fully incorporated before the mixture was stirred at 70 °c for 3 hours. the solution's ph was increased to 12. the ph was changed using 1.0 m h2so4 and 1.0 m naoh solutions. the fact that the color of the solution changed from dark brown to light yellow shows that zno nps were made during the reduction process. the yellow zno nps precipitate was taken out with vacuum filtration. then, it was washed over and over with ethanol and distilled water. in the synthesis, the washing and rinsing procedures are essential because they stop nanoparticles from oxidizing too quickly. the resulting yellow precipitate was dried at 80 °c before being crushed using a mortar and pestle into a fine powder. figure 1 shows below the steps of zno nps preparation. the other zno nps preparation procedure involved the calcination of the resultant zno nps after filtration and washing. the calcination process was carried out at 400 °c for 2 hours [15]. fig. 1. schematic diagram of znonps preparation. 3. results and discussion 3.1 characterization of e-zno-nps different techniques are used to characterize zno nps to demonstrate the nanoparticles' structure, size, surface area, and chemical constituents. the fe-sem analysis was used to identify the zno nps structure, morphology, and particle size (tescan vega 3, usa). the edax technology classifies specific chemicals. ftir spectroscopy (shimadzu,japan) identifies functional groups of zno-nps. the afm analysis (tt-2, usa) is used to examine the surface topology, and zeta potential analyses are an essential tool for evaluating the stability of particles. 3.1.1 fourier transform infrared spectroscopy (ftir) analysis the functional groups of zno nps were characterized by fourier transform infrared (ftir) spectroscopy (shimadzu, japan) using a midir spectrum (400-4000cm-1) , as shown in figure zahraa a. najm al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 2332 (2023) 26 2. significant eucalyptus leaf extracts peak to exhibit a broad band at 3414 and 3425.5 cm1due to the o-h stretching of polyphenols [16]. the following band at 1543 is related to the aromatic c═c stretching [17]. the band at 1481.3 cm1is caused by the presence of the tertiary alcohol (coh) group. a thin, narrow absorption band shows the c-o stretching vibrations of carboxylic acids at 1045.4 cm-1 (cooh). similarly, peaks have been observed at 869.9 cm1corresponding to the isoprenoids and organic acids in eucalyptus extract [7]. these functional groups show that eucalyptus extract contains a biomolecule that is vital in acting as a capping agent to avoid the aggregation of nps. the presence of zno nps is demonstrated by the peaks between 439.7 and 416.6 cm-1 [18]. fig. 2. ftir of znonps. 3.1.2 scanning electron microscopy (sem) and energy dispersive xray spectroscopy (edax) analysis sem analysis of zno nps showed that nps generally had pores and a spherical shape, with a size ranging from (22 to 37 nm) as shown in figure 3. additionally, polyphenol plays a crucial role as a capping agent by covering the surface of zno nps. as a result, only minimal agglomeration is seen in fe-sem analysis, which prevents the agglomeration of nps [19]. moreover, the edax analysis illustrated the constituents and chemical composition of e-zno-nps. as shown in figure 4, according to the zno nps edax analysis, the sample comprises zinc, oxygen, and gold. the sample is primarily made up of zno, as seen by the zinc and oxygen peaks' high intensities. the weight percents of zinc, oxygen, and gold in the zno-nps sample were 73.4%, 4.619%, and 21.97%, respectively. the atomic percent of zinc was 59.32%, followed by 29.26% for the atomic oxygen percent. however, o indicated the eucalyptus leaf extract's inclusion of polyphenols and other organic compounds [13]. the sample coating used for fesem imaging caused the gold to be there. additionally, the edax spectrum showed two distinct peaks for zinc at energies of 1 kev and 8.7 kev and a single peak for oxygen at a wavelength of 0.5 kev, indicating the presence of zn as zno-nps [15]. fig. 3. sem image of zno nps. zahraa a. najm al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 2332 (2023) 27 fig. 4. edax analysis of zno nps. 3.1.3 atomic force microscopy (afm) afm analysis gives us insight into the topography and roughness of nanoparticles [20]. the 3d image of afm illustrated in figure 5 demonstrates a smooth surface of nanoparticles with various particle sizes and types. the fabricated nanoparticles are round and triangular and range in size from 14 to 30 nm. fig. 5. afm analysis of zno nps. 3.1.4 zeta potential (zp) analysis the determination of zeta potential is a crucial tool for providing stabilization for particles. nanoparticles are stable because of their high zeta potential, which prevents them from aggregating, while their low potential leads to flocculation. a high negative value of -95.91 mv was obtained from zeta potential analysis, providing good stability of zno nps as illustrated in figure 6; this zahraa a. najm al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 2332 (2023) 28 stability derives from existing phenolic substances in the eucalyptus leaf extract [21]. furthermore, eucalyptus leaf extract biomolecules are responsible for the higher surface charge [9,22]. fig. 6. zeta potential analysis of zno nps. 3.1.5 brunauer -emmett-teller (bet) analysis the specific surface area (ssa), pore size, and pore volume of zno-nps were analyzed by bet analysis. the ssa, pore volume, and pore size were 26.318 m2/g, 0.098 cm3/g, and 11.118 nm, respectively. because the pore size falls within the range, the results indicate that zno-nps are mesoporous particles [23]. the high ssa proves the ability of these low-cost zno-nps to adsorb pollutants [24]. 4. analytical methods 4.1 calibration curve a calibration curve for standard acid black 210 (ab210) solution was performed to determine the dye's maximum wavelength (λmax) and get the equation that connects the absorbance with concentration. as seen in figure 7, the most significant wavelength of ab210 was determined to be 465 nm. there are different peaks in the scan at 316.5, 461.5, and 606 nm. however, the maximum wavelength is 465 nm because it gives the maximum absorbance. the adsorption capacity at equilibrium 𝑞𝑒 is defined as the relation of adsorptive amounts (mg) to adsorbed amounts (g), and it may be calculated using the formula: 𝑞𝑒 = 𝐶𝑂 − 𝐶𝑒 𝑊 ∗ 𝑉 … (1) where v is the volume of the working solution, co is the initial concentration, ce is the equilibrium concentration of the adsorbate (mg.l-1), and w is the amount of adsorbent (g). the removal efficiency (re) was estimated using the formula below ; 𝑅𝐸% = 𝐶𝑂 − 𝐶𝑡 𝐶𝑂 𝑋 100 … (2) whereas ct is the ab-210 concentration at any time zahraa a. najm al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 2332 (2023) 29 fig.7. calbiration curve of ab210. 4.2 batch adsorption experiments after the nanoparticles had been fully prepared and characterized, batch adsorption experiments were performed to test the efficiency of calcinated and uncalcinated zno nps in removing ab210 from simulated wastewater. a 1 l of ab210 with a concentration of 25 mg/l was formed, then the ph was regulated, and the temperature was 5 and 45 °c, respectively. to start the experiment, 0.75 g/l of zno nps was added into ab210 solution at an agitation speed of 150 rpm, and the experiments lasted up to 180 min; λmax of ab210 we chose from calibration curve to be 465 nm; through the experiments, a10 ml samples were withdrawn at regular intervals and filtered with a 0.45 μm trying filter. the concentration of ab210 was determined using a uv-vis spectrophotometer (shimadzujapan), and the removal rate was utilized using eq. 2. as depicted in the following figure, the removal rate of uncalcinated zno nps was 59%, whereas the calcinated zno nps gave a removal efficiency of 57%. this slight difference in the removal of ab210 could be explained by the loss of some biomolecules from zno nps during the calcination process, which reduces the stability of zno nps. fig. 8. the ab-210 removal by e-zno-nps 0.75 g/l dose, ph=5, initial concentration= 5 mg/l, temperature=45℃, agitation speed=150 rpm, and time 180 min. zahraa a. najm al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 2332 (2023) 30 5. conclusions this study involved a green economic approach to producing zno nps created by combining zinc sulfate salt and eucalyptus leaf extract. eucalyptus leaf extracts contain active components that function as a reducing agent and a capping and stabilizing agent. the characterization of zno nps revealed that they were porous and had a spherical shaper, with nanoparticles ranging in size from 22 to 37 nm. additionally, zno nps exhibited high stability with a zeta potential of -95.91 mv. furthermore, the adsorption results indicate that the calcinated zno nps have a lower dye removal efficiency (57%) than the un-calcinated zno nps, which have a removal efficiency of 59%. acknowledgements the authors are highly indebted to the department of biochemical engineering, alkhwarizmi college of engineering, at the university of baghdad, iraq, and the environment and water directorate of the ministry of science and 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(2023) 23-32، صفحة 3، العدد19لدمجلة الخوارزمي الهندسية المج زهراء عقيل نجم . 32 التوليف األخضر وتوصيف جزيئات أكسيد الزنك النانوية باستخدام أوراق الكالبتوز إلزالة صبغة الوسط المائيالحمضية السوداء من 210 ***نجاح المحنة عبد المالك ميالد شاكر** زهراء عقيل نجم* *****محمد عبد عطية السراج ***احمد خضير حسان* **قسم الهندسة الكيميائية االحيائية/ كلية الهندسة الخوارزمي/ جامعة بغداد/ بغداد/ العراق****، المرقيب / ليبياجامعة ** الجامعة األلمانية للتكنولوجيا في عمان / عمان*** دائرة البحوث ومعالجة المياه/ وزارة العلوم والتكنولوجيا/ بغداد/ العراق*** zhraqylnjm@gmail.comد االلكتروني: *البري dr_eng.malik@yahoo.co.uk **البريد االلكتروني: najah.almhanna@gutech.edu.om : البريد االلكتروني*** ahmedkhh71@gmail.comااللكتروني:بريد *ال*** atiya@kecbu.uobaghdad.edu.iq**البريد االلكتروني:** الخالصة ( باستخدام كبريتات الزنك. zno nps (لتصنيع جزيئات أكسيد الزنك النانوية )تستخدم هذه الدراسة طريقة تركيب صديقة للبيئة ومنخفضة التكلفة . تمت دراسة التركيب والتشكل والسلوك الحراري والتركيب الكيميائي والتركيب zno nps لتصنيع مستخلص أوراق األوكالبتوس هو عامل تغطية واختزال fe-أكدت صور .zeta و afmو edaxو sem-feو ir-ftباستخدام تحليل احتمالية znoالكيميائي والخصائص البصرية للجسيمات النانوية sem أنzno nps ( نانومتر كانت بلورية وكروية. تم استخدام طريقتين إلعداد 22-37بمدى حجم ). zno nps الناتج كلسنة تضمنت الطريقة األولى zno nps والطريقة الثانية بدون تكليس. تم استخدامzno nps 210المحضرة كمواد ماصة إلزالة الصبغة السوداء الحمضية () ab210 ) من مياه ٪ على التوالي. 59٪ و 57المكلس وغير المكلس zno npsالصرف الصحي. كانت كفاءة اإلزالة باستخدام mailto:zhraqylnjm@gmail.com mailto:dr_eng.malik@yahoo.co.uk mailto:najah.almhanna@gutech.edu.om***البريد mailto:najah.almhanna@gutech.edu.om***البريد mailto:ahmedkhh71@gmail.com mailto:atiya@kecbu.uobaghdad.edu.iq this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 21, no. 1, march, (2025), pp. 1-12 analysing geothermal heat exchangers using comsol nonisothermal pipe flow model mohammed a. atiya1, ali naser hussien2, azher m. abed3, philippe mandin4 and farkad ali lattieff 5* 1 department of biochemical engineering, al-khawarizmi college of engineering, university of baghdad, baghdad, iraq 2department of biomedical engineering, university of technology, baghdad, iraq 3 department of air conditioning and refrigeration, al-mustaqbal university, babylon, iraq 4 institut de recherche dupuy de lôme, université de bretagne sud, irdl umr cnrs 6027, lorient 56100, france 5 department of energy engineering, college of engineering, university of baghdad, baghdad, iraq corresponding author’s email: farkad.ali@coeng.uobaghdad.edu.iq (received 19 october 2024; revised 9 january 2025; accepted 19 january 2025; published 1 march 2025) https://doi.org/10.22153/kej.2025.01.001 abstract earth–air heat exchangers (eahe) hold great promise for reducing typical air conditioning systems’ energy consumption whilst preserving high indoor comfort. the present analyses a 3d model using comsol multiphysics software for a geothermal heat exchanger to examine the thermal behavior along the piping system. the experimental findings of the real eahe in baghdad city during january and june are transferred into the nonisothermal pipe flow interface for modeling temperature, velocity and pressure distributions along the piping system. the temperature variation of subsurface soil and the radial temperature distribution around the pipe are modeled into the heat transfer interface. the magnitude of heat flux is also computed in different times along the pipe. the effects of the continuous operation of eahe on the output temperature and on the soil temperature around the pipe are also considered. the model’s output demonstrates that the air temperature rise in january is 10 °c, whereas the air temperature drop is 14 ℃ in june. the effect of extracted/absorbed heat transfer from/to air in pipes is extended up to 0.7 m in the radial direction of the soil surrounding pipes due to continuous airflow in eahe. keywords: geothermal energy; sandy soil; earth heat exchanger; comsol; thermal analysis 1. introduction as the global economy continues to expand, more energy is being used to power conventional air conditioning and refrigeration equipment in buildings and industries. the primary mechanism for transferring heat between various media is the heat exchanger [1-3]. one of the primary uses of heat exchangers is air conditioning, and their shapes and designs vary according to the advantages they offer [4-6]. earth–air heat exchanger (eahe) is a pipe extended in the earth at a few meters depth where the soil is far from the weather fluctuations in winter and summer. moreover, the temperature is moderate, and its variation is very small; thus, it is a good means for heating in winter and cooling in summer. a further advantage is that it is a potential technology for lowering the quantity of electricity that is consumed. recently, the application of the eahe has extended to a wide range of uses such as markets, swimming pools, housing and commercial buildings, industry and agriculture applications [710]. various studies outline a design technique for improving the heat transferred between the interior buried pipes and the surrounding soil [11-14]. numerous advances in numerical simulation models have been achieved to predict the performance of horizontally laid-out earth air heat mailto:farkad.ali@coeng.uobaghdad.edu.iq https://doi.org/10.22153/kej.2025.01.001 mohammed a. atiya al-khwarizmi engineering journal, vol. 21, no.1, pp. 1-12 (2025) 2 exchangers [15–18]. mohammed h. ali et. al. presented a matlab/simulink model to forecast soil temperature distribution and effective eahes [19]. they created this model based on their experimental results to prove the multiple–single pipe eahe is better in terms of pressure loss and cooling potential compared with the twisted–single pipes one. in addition, they claimed that their model could be used to estimate the soil temperature at any depth. hussein, a.n., conducted a numerical study on eahe for different input temperatures on hot days in baghdad city and considered the effect of soil thermal saturation on the lessening of air cooling [20]. performing an extensive 3d analysis of eahe performance is difficult, and various effective parameters increase the use of computational fluid dynamics (cfd)-based simulation software. this software provides simple, powerful solution methods. numerical simulation depends on experimental measurements demonstrated by flagamaryanczyka et al., [21] eahe for passive ventilation in the winter of poland and the simulation performed by cfd software package of ansys fluent. the study showed a satisfactory approximation between numerical and value with the average difference does not accede 1.7 °c. ramırez-davila et al., [22] conducted a comparative analysis study to determine the performance of the eahe system in sandy, salty and clay soils in ciudad juarez, mexico city, and merida, respectively. they used a cfd code to model the system. the simulation results indicated that the average air temperature decreases by 6.6 °c and 3.2 °c in summer for ciudad juarez and mexico city, respectively, and rises by about 2.1 °c and 2.7 °c in winter for ciudad juarez and mexico city, respectively. for merida, the increase of air temperature is 3.8 °c. the study proved the suitability of the eahe for extreme and moderate weather temperatures. a simulated study introduced by naqash et. al. [23] using a comsol multiphysics as a cfd tool provided valuable results about the advantages of using eahe, especially in severe hot or cold climates. the study was validated by a broad field test, designed for islamabad’s soil properties and climatic conditions. the results concluded that the eahe can work as a boosting system for airconditioning devices and decreases the electric energy cost by about 30% to 60%. baghdad records the highest temperatures during summer, and the need for electrical energy for cooling purposes increases. temperatures drop during winter, especially at night, so using eahe as a renewable energy source to meet the increasing need for energy is very appropriate. in the present paper, the system of eahe is designed and implemented practically as an experimental test system. the practical measurements such as temperatures of air and soil, and air pressure and velocity, are taken and transferred as input data of comsol multiphysics software, to obtain a complete analysis of the system. the aims of the paper can be summarised as follows: 1. create a comprehensive 3d modelling of the air and the soil surrounding the eahe system using a cfd code comsol multiphysics 2. calculate the air temperature difference through the eahe in summer and winter due to heat transfer, which is the purpose of using eahe 3. evaluate the effect of continuous operation of eahe on its performance and the soil temperature around the pipe. 2. system description the schematic of the experimental eahe prototype drawn by comsol multiphysics software is shown in fig. 1. this prototype, which is designed to cover the test of various operating air conditions in summer and winter, is fabricated at the university of baghdad, iraq, and consists of a centrifugal blower of 300-watt capacity and a series of pvc pipes with 0.1m diameter and 0.005 m thickness. the pvc pipes are extended vertically downward to a four-meter depth and then extended horizontally to three pipe segments; two of them are parallel, 8 m long and connected by a third segment of 2 m length. the last part of the pvc pipes that completes the open circuit eahe is the 4 m length of vertical upward pipe. the total pipe length is 26 m; 18 m forms the horizontal buried part, and 8 m form the two equal and parallel vertical downward and upward parts. the velocity of the ambient air can be controlled by a variable opening gate installed at the entrance air inlet of the blower. the outlet air enters a caravan installed to monitor the air condition results. the air temperature at the inlet, outlet and along the eahe and the air velocity, in addition to the soil temperature at different locations near the eahe, are the main important parameters, that must be measured to obtain the required data for numerical simulation. for this object, seven thermocouples (type k) are distributed at equal distances, to measure the air temperature at the inlet, outlet and inside the pipe (tin, t1, t2, t3, t4, t5 and tout). another set of five thermocouples is located at mohammed a. atiya al-khwarizmi engineering journal, vol. 21, no.1, pp. 1-12 (2025) 3 different levels in the soil to measure the disturbed and undisturbed temperatures of the soil (t6, t7, t8, t9 and tsoil). all thermocouples are connected to a data logger of 32 channels. type ckt4000 series multichannel temperature recorder uses 32-bit highspeed cpu for data processing and records every 60 s. pressure drop does not affect heat exchange during the eahe, so it is not considered in the experimental measurement. a computer collects and processes the measurement data acquired by the data logger. the air velocity is measured by a vanetype anemometer at the pipe exit and controlled manually. the overall system installation is shown in figure 1. table 1, experimental findings of eahe on the first day of operation month time (hours) 𝐓𝐢𝐧𝐥𝐞𝐭 𝐚𝐢𝐫 (°𝐂) 𝐓𝐨𝐮𝐥𝐞𝐭 𝐚𝐢𝐫 (°𝐂) 𝐓𝐬𝐨𝐢𝐥 (°𝐂) 𝐚𝐭 𝟒 𝐦 𝐝𝐞𝐩𝐭𝐡 january 12 10 21.5 25.7 june 14 46 32 23.9 fig. 1. experimental earth heat exchanger prototype 3. model explanation the nonisothermal pipe flow cfd tool is used to model the temperature, velocity and pressure fields in eahe pipes. this model uses functions and experimental findings to represent the actual operating situations. the nonisothermal pipe flow interface constructs and solves the temperature and fluid flow equations for the soil and pipes system, where 3d lines represent the geometry. figure 2 indicates the piping system and soil geometry mesh is created by comsol multiphysics software. time-dependent surface temperature matches normal conditions of baghdad city temperature fluctuations. however, the ambient temperature above the surface may drop to the lowest temperature of 8 °c during january and the highest one of 43 °c during june. the physical properties of air as a function of temperature are directly available from the software’s built-in material library. fig. 2. piping system and soil geometry mesh in comsol the transient heat conduction in 2d (r: radial and x: axial) coordinate is [24]. 𝜌𝑐𝑠 𝑘𝑠 ( 𝜕𝑇 𝜕𝑡 ) = 𝜕2𝑇 𝜕𝑥2 + 𝜕 𝑟𝜕𝑟 (𝑟 𝜕𝑇 𝜕𝑟 ), …(1) where ρ is the soil density, cs is the soil specific heat capacity and ks is the soil coefficient of thermal conductivity. the air in eahe absorbs/releases heat rate in winter/ summer according to paepe and janssens [25]: 𝑄 = �̇�𝑎𝑐𝑝(𝑇𝑜𝑢𝑡 − 𝑇𝑖𝑛)) , …(2) where �̇�𝑎 , 𝑐𝑝, tout and tin are air mass flowrate, air specific heat capacity, outlet air and inlet air temperature, respectively. this heat rate takes a positive and negative sign in winter and summer, respectively, according to the temperature difference sign. this heat rate exchanges with the soil surrounds the pipe and computed according to paepe and janssens [25]. 𝑄 = ℎ𝐴∆𝑇𝐿𝑀 , …(3) mohammed a. atiya al-khwarizmi engineering journal, vol. 21, no.1, pp. 1-12 (2025) 4 where h is the convective heat-transfer coefficient, a is the pipe surface area and δtlm is the mean logarithm of temperature difference and computed as [25]. ∆𝑇𝑙𝑚 = (𝑇𝑜𝑢𝑡 − 𝑇𝑖𝑛) ln [ (𝑇𝑤𝑎𝑙𝑙−𝑇𝑖𝑛) (𝑇𝑤𝑎𝑙𝑙−𝑇𝑜𝑢𝑡) ]⁄ …(4) from eqs. (2) and (3) and eliminate 𝑄ℎ with substitute eq. (4), the 𝑇𝑜𝑢𝑡 is computed as follows: 𝑇𝑜𝑢𝑡 = 𝑇𝑤𝑎𝑙𝑙 − (𝑇𝑤𝑎𝑙𝑙 − 𝑇𝑖𝑛)exp (− ha 𝑚 ̇ 𝑐𝑝⁄ ) …(5) the heat-transfer coefficient by convection h is computed as holman [26]: ℎ = 𝑁𝑢 ∗ 𝑘𝑎𝑖𝑟/𝑑 , …(6) where kair is the conductive heat transfer of air, d is the diameter of the pipe and nu is the nusselt number computed by singh [27] and lemmon and jacobsen [28]: 𝑁𝑢 = 0.023 ∗ 𝑅𝑒0.8𝑃𝑟𝑛 …(7) the index n is a constant of 0.4 or 0.3 corresponding to heating or cooling operation, respectively. re and pr that appear in above eq. are reynolds and prandtl numbers, respectively, and can computed as [24]: 𝑅𝑒 = 𝜌𝑎𝑖𝑟𝑣𝑑 𝜇⁄ , 𝑃𝑟 = 𝜇𝑐𝑝/𝑘𝑎𝑖𝑟 ...(8) where ρair, v and μ are respectively the density, velocity and absolute viscosity of the air. the air pressure drop in the eahe is due to friction, with a smooth inner pipe wall assumption (cengel and cimbala, 2014) [29]: ∆𝑝 = 𝑓𝜌𝑎𝑖𝑟 𝐿 𝑑 𝑣2 2 …(9) where f and l are the friction factor and pipe length respectively, and f is calculated as [29]: 𝑓 = 64 𝑅𝑒 𝑖𝑓 𝑅𝑒 < 2300⁄ …(10) and 𝑓 = (1.82 log 𝑅𝑒 − 1.64)−2 𝑖𝑓 𝑅𝑒 ≥ 2300 …(11) the experimental measurements reveal that the reynolds number is much greater than 2300. the experimental measurements reveal that the reynolds number is much greater than 2300. the pressure drop due to elbows can be calculated as [29]. ∆𝑝 = 𝐾𝜌𝑎𝑖𝑟 𝑣2 2 , …(12) where k is the loss coefficient of the elbow and equal to 0.9. the power needed for air-flow can be calculated as [29]: 𝑃𝑓 = ∆𝑝 ∗ �̇� …(13) table 2, model input notation 𝒌 𝝆 𝑪𝒑 pipe 0.16 1380 900 soil 1.5 1742 1175 4. results and discussion a numerical modeling of eahe using comsol multiphysics software based on experimental measurements is used. the measurements are conducted in summer and winter. the ambient temperature variation along the year and the temperature variation against the depth underground in january (winter) and june (summer) are shown in figure 3 a and b, respectively, whereas the temperature variation with depth of 3d pipe–soil configuration without airflow is indicated in figure 4 for the two months. the temperatures converge with increasing depth despite the different ambient temperatures through the january and june months. by contrast, the temperature of the earth’s surface and the nearest subsurface are affected by the hourly variation of ambient temperatures. )a) (b) fig. 3. (a) variation of ambient temperature and (b) soil depth temperature during the coldest (january) and hottest (june) months mohammed a. atiya al-khwarizmi engineering journal, vol. 21, no.1, pp. 1-12 (2025) 5 january june fig. 4. profiles of soil depth and eahx temperatures when no air flow rate (u = 0 m/s) the average air velocity vectors and the air temperature variation inside the pipe during january and june are illustrated in figure 5. the blower is placed at the pipe inlet, and the average air velocity changes from the inlet to the outlet from 1 m/s to 1.06 m/s, in january, and from 1 m/s to 0.93 m/s in june. this increase in average air velocity in january and decrease in june can be attributed to the effect of air density variation, that is, the cold air of high density goes down at the inlet and the hot air of low density goes up at the outlet. moreover, the direction of the air being pushed by the blower during winter leads to an increase in the average air velocity from the inlet to the outlet. on the contrary, the blower pushes the hot air down at the inlet and the cold air up at the outlet, opposite to the density gradient of the air, so the average air velocity decreases from the inlet to the outlet in summer. the increase of the air temperature by 10 ℃ as a heating effect at 2 am, in the first day of operation in january and its decrease by 14 ℃ as a cooling effect at 2 pm on the first day of operation in june, are presented in figure 5. june mohammed a. atiya al-khwarizmi engineering journal, vol. 21, no.1, pp. 1-12 (2025) 6 january fig. 5. variation of average air velocity and air temperatures along the eahx pipes during june and january figure 6 shows similar temperature changes along the eahe pipe. the air temperature drop on june 14 ℃ is higher than that of january of 10 ℃ due to the high-temperature difference between the inlet air temperature of 46 ℃ and the soil undisturbed temperature of 23.9 ℃ in june. this difference is lower in january, which is 10 ℃ for inlet air and 25.7 ℃ for undisturbed soil. these differences lead to high heat flux transferred when high-temperature differences occur, and vice versa. fig. 6. air temperature profile along the eahx pipes during june and january figures 7 and 8 show the heat flux variation along the pipe between the air and the soil for january and june, respectively. the hourly ambient temperatures are measured during the four days of eahe system operation. for january, the times of 2:00 am and 12:00 pm are selected as a case study of heat flux changes, as shown in figure 7, whereas for june, 8 am and 2 pm are selected, as illustrated in figure 8. the nonisothermal model is used to calculate the heat losses/stored in the soil during the continuous operation of the four consecutive days. the positive and negative parts of heat flux refer to the direction of heat from soil to air and from air to soil, respectively, as presented in figure 7. by contrast, the air cooling and heating are represented by positive and negative heat fluxes, respectively, for june, as shown in figure 8. however, the maximum heat flux occurs at the maximum temperature difference between the soil and air, that is, at 2:00 am in january and at 2:00 pm in june. this difference in temperature between the air and soil is higher than that at 12:00 pm in january and 8:00 am in june, especially on the first day of operation, and then gradually decreases in the three other consecutive days due to the continuous heat losses from the soil in january and continuous heat gain to the soil in june. the maximum heat fluxes in january at 2:00 am along the four consecutive days are 51.5, 34.7, 32.2 and 30.2 w/𝑚2, whereas the maximum heat flux at 12:00 pm does not exceed 8.4 w/𝑚2 for the same days. the peak heat flux values in june occur at 2:00 pm and are 41.2, 37.7, 36.4, and 35.7 w/𝑚2 for the four consecutive days, whereas the maximum heat flux values reach 15.2 w/𝑚2 at 8:00 am. the heat flux values at the first and last four meters of the vertical pipe length, and the temperature of the soil increases gradually with increasing the depth in january and on the contrary in june. figs. 7 and 8 show that the heat transfer can be changed in the direction from the negative at 12:00 pm when the air is cooled by the value exceeded to about 20.3 𝑊/𝑚2 in january and at 2:00 am in june when the air is heated to about 14 𝑊/𝑚2. mohammed a. atiya al-khwarizmi engineering journal, vol. 21, no.1, pp. 1-12 (2025) 7 fig. 7. variation of heat flux along the eahe pipes in january fig. 8. variation of heat flux along the eahe pipes in june. the temperature distributions along the vertical and the horizontal parts of eahe are illustrated in figure 9 and 10. on the third day of the continuous operation at 8:00 pm in january, fig. 9 shows the effect of heat transfer from the soil to the buried pipe inside it. the disturbed soil temperature variations form a truncated cone of the base radius equal to about 0.7 m, at the inlet of the horizontal part and about 0.3 m at the end of it, after two days and 20 hours in january. the disturbed temperature near the pipe at the beginning and the end of the horizontal part are to 18c°c and 22 °c, respectively, in january whereas the undisturbed soil temperature is 25.7 °c. mohammed a. atiya al-khwarizmi engineering journal, vol. 21, no.1, pp. 1-12 (2025) 8 fig. 9. temperature variation of air in the pipe and the soil around it at 8:00 pm on the third day of continuous operation in january figure 10 illustrates the temperature changes for the piping system and the surrounding soil in june after two days and 15 h of continuous operation. the disturbed soil temperature at the beginning and the end of the horizontal part are 34.5 °c and 27 °c, respectively, with 23.9 °c of undisturbed soil temperature. fig. 10. temperature variation of air in the pipe and the soil around it at 3:00 pm on the third day of continuous operation in june mohammed a. atiya al-khwarizmi engineering journal, vol. 21, no.1, pp. 1-12 (2025) 9 fig. 11. pressure drop along the eahe pipe the formation of these regions around the pipe reduces the temperature differences between the soil and the air, which leads to a decrease in the air heating and soil temperature in january, a decrease in the air cooling and an increase in the soil temperature in june. moreover, these figures show the effects of the soil temperature gradient in the vertical parts and the influence of continuous operation on the eahe system performance. the temperature distribution in vertical parts of the eahe system indicates the cooling of air in the vertical part before the pipe outlet in january and the heating of air in this part in june because the soil temperature is close the ambient air temperature; therefore, this part decreases the benefit of eahe, and the pipe in this part must be completely insulated. the pressure drop along the pipe due to friction and due to 4 elbows is shown in fig. 11. the pressure drop due to friction increases by 0.214 pa for each meter of pipe length, and the pressure drop due to the elbows increases by 0.549 pa for each elbow the pressure drop at the exit, that is, 7.77 pa represents the total pressure drop along the pipe. this value is multiplied by the air discharge as explained by eq. (13) to calculate the power losses due to friction and elbows, which is 0.06 w. 5. conclusions the use of eahe is a satisfactory, clean choice for cooling/heating air or decreasing the cost of traditional energy systems when it is invested wisely. nonisothermal analysis or the consideration of the soil temperature variation achieves higher accuracy and more reality in studying the performance of the eahe system. the continuous operation or continuous air passing through the pipes of eahe reduces the air heating in winter and air cooling in summer. the vertical part of the pipe at the outlet must be surrounded with low thermal conductive material to lessen the disadvantage of heat transfer in this part due to temperature variation toward the ground surface. nomenclature 𝐴 𝑚2 cross-section area of the pipe 𝐴𝑠 𝑚2 surface area of the pipe wall 𝐶𝑝 𝐽/𝑘𝑔. ℃ heat capacity at constant pressure 𝑑ℎ 𝑚 hydraulic pipe diameter 𝐹 𝑁/𝑚3 volume force (gravity) ℎ 𝑊/𝑚2. ℃ heat transfer coefficient 𝑘 𝑊/𝑚. ℃ thermal conductivity 𝑝 𝑁/𝑚2 pressure 𝑞𝑐𝑜𝑛𝑑 𝑊/𝑚2 conductive heat flux 𝑞𝑐𝑜𝑛𝑣 𝑊/𝑚2 convective heat flux 𝑄 𝑊/𝑚2 heat source 𝑟𝑖 𝑚 wall inner radius 𝑟𝑜 𝑚 wall outer radius 𝑇 ℃ temperature 𝑢 𝑚/𝑠 fluid velocity ρ 𝑘𝑔/𝑚3 density ∇ gradient operator mohammed a. atiya al-khwarizmi engineering journal, vol. 21, no.1, pp. 1-12 (2025) 10 references [1] mutlak fa-h. construction and performance study of a solar powered hybrid cooling system in iraq. iraqi journal of physics. 2019, 24, 11(21):91-101. 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(2025) 1-12، صفحة 1، العدد21مجلة الخوارزمي الهندسية المجلد محمد عبد عطية السراج 12 باستخدام التدفق غير المتساوي الحرارة لألنابيبذي تحليل المبادالت الحرارية األرضية برنامج الكومسل محمد عبد عطية السراج 1، علي ناصر حسين 2، أزهر محسن عبد 3، فيليب ماندين4، فرقد علي لطيف5* ، بغداد، العراقجامعة بغداد ،الخوارزمي، كلية الهندسة قسم الهندسة الكيميائية االحيائية.1 ، بغداد، العراقالجامعة التكنولوجية ،قسم الهندسة الطبية الحيوية 2 ، بابل، العراقجامعة المستقبل ،قسم التكييف والتبريد 4 ، فرنسا56100لوريان ،جامعة بريتان سود معهد البحوث دوبوي دي لوم، 4 العراق بغداد، جامعة بغداد،قسم هندسة الطاقة، كلية الهندسة، 5 farkad.ali@coeng.uobaghdad.edu.iq االلكتروني :البريد * المستخلص ( بوعود كبيرة في تقليل استهالك الطاقة ألنظمة تكييف الهواء النموذجية مع الحفاظ على الراحة eaheتتمتع المبادالت الحرارية األرضية الهوائية ) لمبادل حراري أرضي لفحص السلوك comsol multiphysicsالداخلية العالية. اعتمدت الدراسة الحالية تحليل نموذج ثالثي األبعاد باستخدام برنامج نقل النتائج التجريبية لمبادل حراري أرضي هوائي حقيقي في مدينة بغداد خالل شهري يناير ويونيو إلى واجهة تدفق الحراري على طول نظام األنابيب. تم التربة تحت األنابيب غير المتساوية الحرارة لنمذجة توزيع درجات الحرارة والسرعة والضغط على طول نظام األنابيب. تم نمذجة التغير في درجة حرارة تم أيًضا حساب حجم تدفق الحرارة في أوقات مختلفة على طول األنبوب. ودرجة الحرارة الشعاعية حول األنبوب في واجهة نقل الحرارة. السطحية وتوزيع تب. أظهرتأخذ الدراسة في االعتبار تأثيرات التشغيل المستمر لمبادل حراري أرضي هوائي على درجة حرارة اإلخراج ودرجة حرارة التربة حول األنبو درجة مئوية في يونيو. يمتد 14درجات مئوية، في حين أن انخفاض درجة حرارة الهواء هو 10ناتج النموذج أن ارتفاع درجة حرارة الهواء في يناير هو بب تدفق الهواء المستمر في متر في االتجاه الشعاعي للتربة المحيطة باألنابيب بس 0.7تأثير نقل الحرارة المستخرجة/الممتصة من/إلى الهواء في األنابيب حتى eahe. mailto:farkad.ali@coeng.uobaghdad.edu.iq 1. introduction as the global economy continues to expand, more energy is being used to power conventional air conditioning and refrigeration equipment in buildings and industries. the primary mechanism for transferring heat between various media is the heat exchange... various studies outline a design technique for improving the heat transferred between the interior buried pipes and the surrounding soil [11-14]. numerous advances in numerical simulation models have been achieved to predict the performance of horizon... performing an extensive 3d analysis of eahe performance is difficult, and various effective parameters increase the use of computational fluid dynamics (cfd)-based simulation software. this software provides simple, powerful solution methods. numerical simulation depends on experimental measurements demonstrated by flaga-maryanczyka et al., [21] eahe for passive ventilation in the winter of poland and the simulation performed by cfd software package of ansys fluent. the study showed a sati... ramırez-davila et al., [22] conducted a comparative analysis study to determine the performance of the eahe system in sandy, salty and clay soils in ciudad juarez, mexico city, and merida, respectively. they used a cfd code to model the system. the si... a simulated study introduced by naqash et. al. [23] using a comsol multiphysics as a cfd tool provided valuable results about the advantages of using eahe, especially in severe hot or cold climates. the study was validated by a broad field test, desig... baghdad records the highest temperatures during summer, and the need for electrical energy for cooling purposes increases. temperatures drop during winter, especially at night, so using eahe as a renewable energy source to meet the increasing need for... 1. create a comprehensive 3d modelling of the air and the soil surrounding the eahe system using a cfd code comsol multiphysics 2. calculate the air temperature difference through the eahe in summer and winter due to heat transfer, which is the purpose of using eahe 3. evaluate the effect of continuous operation of eahe on its performance and the soil temperature around the pipe. 2. system description 3. model explanation 4. results and discussion 5. conclusions nomenclature [21] flaga m, schnotale j, radon j and was k, 2014 experimental measurements and cfd simulation of a ground source heat exchanger operating at a cold climate for a passive house ventilation system. energy and buildings. pp 562-570 [22] ramırez l, xaman j a j, alvarez g and hernandez p 2014 numerical study of earth to-air heat exchanger for three different climates. energy and buildings. pp 238-248 this is an open access article under the cc by license : biodiesel production from castor oil nadya hussin al-sbani1, awatif meelad2, omar sultan3, alaa kareem mohammed4*, amani gummah kwadikha5 , and saleh ali tweib6 1,2,3,5department of chemical engineering, faculty of oil, gas, renewable energy engineering, university of zawia, libya 4 department of biochemical engineering, al-khwarizmi college of engineering, university of baghdad, baghdad, iraq 6 department of chemical and process engineering, zawai higher institute of science and technology, al-zawia, libya *corresponding auther’s email :dr.alaa@kecbu.uobaghdad.edu.iq (received 4 december 2024; revised 23 january 2025; accepted 3 march 2025; published 1 june 2025) https://doi.org/10.22153/kej.2025.03.001 abstract biodiesel is becoming one of the most attractive alternative biofuels for petroleum-based diesel fuels. the castor plant is one of the abundant non-edible oils found in many countries. this paper aims to study libyan castor oil and its potential for diesel conversion. experiments were carried out in the laboratories of the specific center for training in the oil industries in al-zawiya. the oil was extracted using a soxhlet extractor and n-hexane solvent at 60 °c. transesterification reactions were conducted in a batch reactor (a three-neck flask was used, where the middle opening carries a reflux condensation unit) at 65 °c. the methanol-to-castor oil molar ratio was 6:1, with a catalyst concentration of 1 wt.% relative to the castor oil, and the reaction time was 30 min. castor oil was analysed and found to have a fatty acid content of 0.7%. the productivity of biodiesel exhibited 80% yield. standard test methods of analysis were conducted to determine the biodiesel’s properties. results indicated that the kinematic viscosity at 40 °c was 14.24 cst, the density was 0.924 g/cm3, the cetane number (cn) was 54 and the pour point was −15 °c, indicating that castor oil biodiesel is of high quality, with a high cn and a low pour point. keywords: biodiesel; castor oil; alkaline transesterification; renewable energy; and non-edible oil. 1. introduction biodiesel is a promising alternative for replacing conventional diesel. countries have produced about 36 billion litres of biodiesel globally [1]. diesel is produced from various sources, such as food waste and animal waste from cows and chickens, which have a high potential to produce biogas due to their high organic content. methane production may be achieved by adding bioaugmentation with bacteria, along with the adjustment of ph and using a semicontinuous system [2, 3]. edible vegetable oils adversely affect the balance between market demands and food supply, accounting for roughly 70%–80% of the total cost of producing biodiesel [4]. as a result, finding less costly and non-edible sources has become the aim of the hunt for substitutes for these food oils. castor seeds are one of these sources; they are regarded as one of the most promising choices for biodiesel because of their high oil content (roughly 46%– 55%) [5, 6]. castor oil is a plant suited to arid regions and dry climates. it is inedible and has no effect on food security. it is also a highly productive plant that grows quickly. castor oil contains high amounts of ricinoleic acid (c18h34o3) at about 80%–90%, which is the basis for producing biofuels. it is also composed of al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 21, no. 2, june, (2025), pp. 1-11 mailto:dr.alaa@kecbu.uobaghdad.edu.iq https://doi.org/10.22153/kej.2025.03.001 nadya hussin al-sbani al-khwarizmi engineering journal, vol. 21, no.2, pp. 111 (2025) 2 3% 6% linoleic acid and 2% 4% oleic acid, and the rest is saturated fatty acids. castor oil produces diesel with a higher viscosity than other oils, making it an ideal choice for improving the viscosity of petroleum diesel and suitable for many industries such as plastics, cosmetics and paint. miscibility, low iodine content and low freezing point make castor oil an appropriate raw material to produce biodiesel [6–8]. all these features of castor oil remarkably reduce the cost of biodiesel production. transesterification is the primary method used to lower the viscosity of vegetable oils and create alkyl esters resembling diesel. hence, transesterified vegetable oils are commonly referred to as ‘biodiesel’. the process involves an ester from one alcohol reacting with different alcohols to produce an ester from the latter alcohol and alcohol from the initial ester, such as methyl acetate and ethyl alcohol forming ethyl acetate and methyl alcohol [9, 10]. several important conditions must be considered for this step: temperature, reaction time, catalysts, moisture, free fatty acid (ffa) content and the effect of the molar ratio between alcohol (methanol or ethanol) and oil (raw material) [8]. fig. 1. transesterification reaction of vegetable oil (triglyceride) and methanol to fatty acid methyl esters (biodiesel) and glycerol high vital diesel fuel is very important to ensure enhanced engine performance with no operating problems. the evaluation of the quality of vital diesel fuel usually depends on physical features and general chemicals that resemble diesel and the chemical composition that affects the specific fuel properties. motor viscosity and density represent the value of acid, pour points, flash points, iodine value, fatty acids and other properties [11, 12]. biodiesel derived from castor oil has benefits of being biodegradable, non-toxic, renewable and safe to handle. it also offers low greenhouse gas emissions, a high flash point and energy similar to that from fossil diesel [13]. biodiesel is crucial for fighting climate change and enhancing air quality, which protects public health and ecological integrity [14]. other advantages of castor beans in the esterification process are high miscibility of alcohol, low reaction temperature, low iodine content and low freezing point [6]. the present work investigated the extraction of castor oil from castor seeds and its ability to produce biodiesel. 2. materials and methods the process of biodiesel production was divided into several levels. fig. 2 shows the flowchart of these steps. experiments were conducted in the laboratories of the specific center for training in the oil industries in al-zawiya, libya. the biodiesel production started with collecting castor beans and preparing them for the next steps. the preparation of castor beans included washing, drying, winnowing and grinding. castor oil was extracted from the seeds via nadya hussin al-sbani al-khwarizmi engineering journal, vol. 21, no.2, pp. 111 (2025) 3 fig. 2. biodiesel production from castor oil by alkaline transesterification reaction the evaporated solvent was reused in the extraction. after castor oil was obtained, it was refined to improve its quality. degumming was the first refining step, followed by determination of the acid content. afterwards, castor oil was prepared to produce biodiesel. transesterification reaction was carried out to produce biodiesel. the triglycerides of castor oil reacted with methanol in the presence of koh as a catalyst. then, the biodiesel was separated from glycerol (byproduct). the final step was purification of the biodiesel by neutralising koh with acetic acid, washing the biodiesel to remove any contaminants (methanol, catalyst and soap), and drying the washing water. then, the biodiesel properties were determined in accordance with astm tests. 2.1. preparation of castor beans for extraction castor beans were collected from farms in surman city, libya. these beans were prepared for oil extraction. the castor plant is shown in figure (3). the castor beans had some undesired materials that should be separated by hand picking. the beans were washed carefully to remove any remaining dirt and then heated in the oven at 70 °c for 72 h to break down the cells containing the oil and dry any moisture present in the seeds. the shell was separated from the seeds by hand. then, the beans were crushed to rupture the cell walls to release castor oil. fig. 3. castor plant 2.2. castor oil extraction castor oil was extracted using the soxhlet apparatus, as shown in fig. (4). a vacuum rotary evaporator was used to extract the solvent from the oil. normal hexane (300 ml) was placed into a round-bottom flask. the thimble containing 10 g of the sample was placed in the extractor’s centre. after the solvent was heated to 60 °c, the vapor rose through the vertical tube and condensed at the top. the liquid condensate trickled into the central thimble, which held the solid sample that was needed to be extracted. the extract was returned to the round-bottom flask after passing through the thimble’s pores and filling the siphon tube. this process was continued for 30 min [15–17]. nadya hussin al-sbani al-khwarizmi engineering journal, vol. 21, no.2, pp. 111 (2025) 4 fig. 4. soxhlet extractor a vacuum rotary evaporator was used to evaporate the hexane solvent from the castor oil. the sample was contained in the evaporation flask while the water bath temperature was 40 °c. after 30 min, the castor oil remained in the evaporation flask, and the solvent was received from the receiving flask. the evaporated n-hexane can be used for the next sample to be extracted. the amount of extracted castor oil was calculated using eq. (1) as follows: % castor oil yield = weight of extracted oil × 100% weight of total sample … (1) the extracted castor oil was refined, and the ffa content was determined to neutralise to prevent the formation of the soap. 2.3. castor oil acid degumming crude castor oil (190 ml) was stirred and heated to 80 °c–90 °c by using a magnetic stirrer. then, 4 ml of citric acid solution (30%) was slowly added to the crude oil. the mixture was stirred for 20 min, cooled to 25 °c, and washed with 10 ml of distilled water. the solution was transferred to a separating funnel to allow the gums to settle in the bottom of the funnel. the solution was settled for 24 h, and the gums were removed from the oil. finally, the oil was transported to a centrifuge to remove the remaining gums and water [16]. 2.4. determination of oil acidity the method of kardash and tur’yan was used to determine the acid value of the samples. this method is based on titration with ethanol, using phenolphthalein as an indicator [18]. the oil sample (1.0 g) was placed into a 250 ml-conical flask, followed by diethyl ether (25 ml), ethanol (25 ml) with 96% purity and three drops of phenolphthalein indicator. then, the mixture was heated for 3 min by using a shaking water bath. afterwards, the mixture was titrated against naoh (0.025 m), with vigorous shaking until a pink colour appeared [19, 20]. the acid value (av) of the oil is expressed in mg naoh per gram of oil. the ffa percent (%ffa) was calculated from the acid value as follows: % 𝐹𝐹𝐴 = 𝐴𝑉 1.99 … (2) 2.5. neutralisation ffa is removed from crude oils via neutralisation. this process was accomplished by adding 0.412 g of naoh (0.1 m) to the degummed castor oil (158 g) and heating the mixture to 85% °c–95 °c, with mixing for about 45–60 min to break any emulsion that may form during neutralisation. the ffas were converted into soap stock, which has a higher specific gravity (sg) than neutral oil and tends to precipitate at the bottom. the mixture then was transferred to a separating funnel. afterwards, the mixture was placed into a separating funnel and left for 24 h to remove the soap that formed. hot water was then added to the oil several times until the soap that was still present in the solution was removed. hot distilled boiling water (30%) was added to hydrate the neutralised oil. the mixture was stirred for 2 min and left in the separating funnel until two distinct phases were visible. the aqueous layer at the bottom was then eliminated. the process needed to be repeated to guarantee that the majority of gums and soaps were removed. the oil was dried in an oven set at 120 °c for 2 h to remove the water [21– 23]. 2.6. determination of the sg of castor oil for the measurement of the specific gravity, sp. gr, a clean and dry volumetric cylinder was used to determine the density of the oil with the volume of 50 ml and its weight (w0). the volumetric cylinder was filled with oil and reweighed to give w1. after the bottle washed and dried, the oil was substituted nadya hussin al-sbani al-khwarizmi engineering journal, vol. 21, no.2, pp. 111 (2025) 5 with water and weighed to yield w2 [24]. then, the sp. gr was calculated as follows: sg = w1− w0 w2− w0 … (3) 2.7. biodiesel production using transesterification as illustrated in figure (5), the reactor, a 250 ml three-neck flat bottom flask, was positioned with a reflux condensation unit in the middle opening (or neck). the thermometer was carried by one of the two side arms, whereas the other side arm served as the reactor’s feed point. the setup was mounted on the hot plate magnetic stirrer. the condenser was then connected to a tap for the inflow and outflow of cold water to prevent alcohol loss during the transesterification reactions. fig. 5. transesterification process initially, 83 g of castor oil was poured into the reactor and heated to 65 °c. a solution of koh in methanol (99.8% pure) was freshly prepared with the following conditions: koh concentration of 1% of castor oil weight and methanol-to-castor oil molar ratio of 6:1. the heated oil was gradually mixed with the catalyst solution. following the reaction, the mixture was left in the separating funnel at room temperature for 24 h to settle under gravity. two layers developed during the separation process, with the glycerol phase at the bottom and the crude ester phase at the top. the tap at the bottom was opened to remove the glycerol phase from the biodiesel [25–27]. after the biodiesel was separated from the glycerine layer, it was purified with warm distilled water. five additional washing steps were conducted with water only. the excess methanol and any remaining water were removed from the biodiesel by heating the biodiesel at 120 °c for 2 h [28]. the biodiesel yield (%) was determined using eq. (4) as follows: biodiesel yield (%) = weight of produced biodiesel (g) weight of raw oil (g) × 100% … (4) 2.8. characterisation of biodiesel 2.8.1. kinematic viscosity (μ) astm d 445 is the standard method for determining the kinematic viscosity of diesel or biodiesel fuels. the viscosity of biodiesel was measured using a viscometer, as shown in fig. (6). the kinematic viscosity was determined at 40 °c. the viscometer was placed in a water bath set at 40 °c. after 10 ml of the sample was added to the viscometer, the sample and the viscometer were left to acclimate to the water bath for 0.5 h. the sample was kept in the water bath until it reached the equilibrium temperature of 40 °c. after the equilibrium temperature was maintained, the time required for the biodiesel to flow under gravity was measured using a calibrated glass capillary tube. the kinematic viscosity was determined using eq. (5) [29] as follows: μ = 0.0079578 × 𝑡, … (5) where μ is the kinematic viscosity in mm2/s, the constant 0.0079578 is the calibration constant of the tube and 𝑡 is the time required for the biodiesel to flow under gravity through a calibrated glass in seconds. fig. 6. kinematic viscometer 2.8.2. pour point astm d97 was used to determine the pour point. the biodiesel was cooled at a predetermined rate, and its flow characteristics were checked at 3 °c intervals. the pour point was the lowest temperature at which the sample movement was nadya hussin al-sbani al-khwarizmi engineering journal, vol. 21, no.2, pp. 111 (2025) 6 detected [30]. the biodiesel pour point was determined using astm d2500. a predetermined cooling rate was applied to the biodiesel and periodically checked. the pour point was determined by measuring the temperature at which a cloud was first seen at the test jar’s bottom [31]. 2.8.3. aniline point the aniline point is the lowest temperature at which equal volumes of aniline (c6h5nh2) and oil form a single phase. it was determined using astm d611. a 10 ml sample of biodiesel was introduced into a test tube. an equal volume of aniline oil was added to the biodiesel. the mixture was combined and heated at a regulated rate to make the two phases miscible. the aniline point or mixed aniline point was then determined by cooling the mixture at a regulated rate and recording the temperature at which the two phases separated [32]. the aniline point test apparatus is depicted in figure (7). fig. 7. aniline point test 2.8.4. sg at 60 °f a clean and dry volumetric cylinder was used to determine the density of biodiesel with a volume of 50 ml and weight w0. it was then filled with biodiesel, plugged and reweighed to yield w1. the oil was replaced with water after washing and drying the bottle and weighed to give w2 [33]. sg was expressed using eq. (6) as follows: 𝑆𝐺biodiesel = 𝑊1− 𝑊0 𝑊2− 𝑊0 … (6) 2.8.5. api gravity the following equation was used to calculate the american petroleum institute (api) gravity on the basis of the biodiesel-sg value: 𝐴𝑃𝐼 = 141.5 specific gravity − 131.5 … (7) 2.8.6. cetane number (cn) the cn index was determined in accordance with the method of boerlage and broeze (1994) [33] by using eq. (8) as follows: 𝐶𝑒𝑡𝑎𝑛𝑒 𝐼𝑛𝑑𝑒𝑥 = 𝐴𝑛𝑖𝑙𝑖𝑛𝑒 𝑝𝑜𝑖𝑛𝑡 (℃) × 𝐴𝑃𝐼 𝐺𝑟𝑎𝑣𝑖𝑡𝑦 10 … (8) 3. results and discussions the extraction results showed that every 1 g of castor beans after washing and drying in the oven yielded 0.51 g of oil, with a production rate of 51%. the raw castor oil produced contains some amounts of mucilage. acid degumming was necessary to remove phosphatides and mucilage from the oil. the amount of lost oil was determined and obtained at 22% of the weight of the oil. the acid number of crude castor oil was 2.6 mg naoh/g oil, indicating an ffa content of 1.3%. when the ffas in the oil reacted with naoh, soap was produced and then removed by washing with distilled water. approximately 47% of the oil was lost during the neutralisation process. after the castor oil was neutralised, the acid number decreased to 1.4 mg naoh/g oil, and the ffa content was 0.7%. after these preparatory processes were performed, the obtained castor oil can be used as a raw material for biodiesel production. the properties are shown in table 1. table 1, castor oil properties property before refining after refining density g/ml at 20 °c --0.952 specific gravity --0.954 acid value naoh/g oil 2.6 1.4 ffa content 1.3% 0.7% after the mixture was allowed to settle for 24 h, the transesterification process resulted in two layers. the lower layer, glycerol (a byproduct), was removed from the separating funnel, whereas the nadya hussin al-sbani al-khwarizmi engineering journal, vol. 21, no.2, pp. 111 (2025) 7 upper layer was biodiesel with a yellow colour. the produced biodiesel underwent purification, where the base catalyst (koh) was neutralised with acetic acid and then washed five times with distilled water to eliminate the residual catalyst and excess methanol, as shown in figure (8). fig. 8. neutralisation and transesterification 3.1. biodiesel yield this process achieved an 80% yield, indicating that the parameters used were effective and could be adjusted for optimal castor oil biodiesel production. however, some alcohol possibly remained unreacted, or some biodiesel was probably lost during the washing stage. this yield from castor oil is better than the results obtained by dias, et al. (2013) [8], which ranged from 43.3% to 74.1%. some studies, such as those by elango, r.k. et al. (2019) and meneghetti, s.m.p. (2006), reported yields exceeding 90% [8, 34]. the reason for the difference in productivity may be due to the nature of the oil and the purity of the raw materials. many researchers have studied the potential yield of biodiesel from non-edible oils, including hevea brasiliensis, ricinus communis, gossypium, and waste cooking oil, with yields of 45%, 48%, 96%, and 59.44%, respectively, when using methanol as the solvent and koh as the catalyst [35]. 3.2. characterisation the comparison results of castor oil biodiesel with petroleum diesel and various international standards are shown in table 2. the produced biodiesel at 40 °c had an extremely high viscosity value (14.24 mm2/s), exceeding the international standard limit (1.9–6 mm2/s). this finding can be attributed to the presence of oh groups in ricinoleic acid tending to form hydrogen bonds with other hydrogen atoms present in other molecules [36]. the obtained biodiesel had a lower viscosity than that obtained by other studies, which were 15.5, 15.17, and 15.98 mm2/s [27]. table 2, properties of the produced castor biodiesel property unit astm test method limits castor biodiesel viscosity at 40 °c mm2/s d445 1.9–6 14.24 density kg/m3 d1298 860–900 924 api gravity ------21.639 pour point ℃ d97 0 -15 cloud point ℃ d2500 report no wax found aniline point ℃ d611 --25 cetane number ----47 (min) 54 high viscosity is a major problem of biodiesel in diesel engines. the high value of viscosity of fuel causes depositions on the engine, which affects its function. thus, the produced biodiesel cannot be directly used in diesel engines. it can be used by blending with petroleum diesel to minimise fuel viscosity. the density of the produced biodiesel at 15 °c was 924 kg/m3, and the sg was 0.9248. this density value is above the international standard limit (860– 900 kg/m3). this high density is a consequence of the presence of the hydroxyl group of ricinoleic acid methyl ester [36]. it can be mixed with diesel without exceeding the standard accepted ratio for biodiesel density. the pour point of the produced biodiesel (−15 °c) was considerably far from the maximum allowed pour point of the european standard en 14213 (0 °c max). this finding indicates that castor oil biodiesel could be used as a petroleum diesel additive for improving cold flow properties. the cloud point was higher than the pour point. the produced biodiesel reached the pour point without the appearance of any wax crystal. some researchers found the cloud points of their biodiesel to be −15 °c [20] and −14 °c [25]. thus, castor oil biodiesel could be used in cold weather as a petroleum diesel additive. the aniline point was determined to be 25 °c, and the cn was 54. this low aniline point may nadya hussin al-sbani al-khwarizmi engineering journal, vol. 21, no.2, pp. 111 (2025) 8 indicate the absence of aromatic compounds in the castor oil biodiesel. the cn of the biodiesel was above the lower limit of the standards (47 min). the high cn value represents its high ability towards ignition in engines after injection [36]. other researchers obtained a varying cn at 43.7 min. this value is lower than that of the standard. other researchers found that the cns of castor biodiesel were 55.82 and 60.2 min [20, 37], respectively. 4. conclusion castor bean plant was used in this study to produce biodiesel. castor oil was extracted, and many steps were taken before biodiesel was created. the beans contained approximately 51% castor oil. a high yield of biodiesel was obtained from castor oil, more than 80%. the fuel properties of the biodiesel obtained from alkaline transesterification of castor oil were determined using standard methods and compared with the standard values of astm specifications. the produced biodiesel had a high cn (54 min) and a very low pour point (−15 °c), makes this biodiesel a good alternative in winter conditions. it also had a high viscosity (924 kg/m3), which makes it unsuitable for use in diesel engines alone. castor oil biodiesel could improve the environmental performance and flow characteristics of petroleum diesel. references [1] n. singh et al., “progress and facts on biodiesel generations, production methods, influencing factors, and reactors: a comprehensive review from 2000 to 2023,” energy conversion and management, vol. 302, p. 118157, 2024, doi: https://doi.org/10.1016/j.enconman.2024.11815 7. 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( 2025) 1-11، صفحة 2العدد، 21مجلة الخوارزمي الهندسية المجلد نادية حسين السباتي 11 إنتاج الديزل الحيوي من زيت الخروع * 4كريم محمد، عالء 3،عمر سلطان2،عواطف ميالد1نادية حسين السباني 6، صالح علي تويب5اماني جمعة كوديخة قسم الهندسة الكيميائية، كلية هندسة النفط والغاز والطاقة المتجددة، جامعة الزاوية، ليبيا ,51,2,3 قسم الهندسة الكيميائية االحيائية، كلية الهندسة الخوارزمي، جامعة بغداد، العراق 4 العمليات، معهد زاوية العالي للعلوم والتكنولوجيا، الزاوية، ليبيا الهندسة الكيميائية وهندسة 6 dr.alaa@kecbu.uobaghdad.edu.iq :البريد االلكتروني* ــ ـــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ ــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ المستخلص تخداًما إلنتاج وقود الديزل يعد وقود الديزل الحيوي أحد أكثر البدائل جاذبية لوقود الديزل القائم على البترول. تعتبر الزيوت النباتية من أكثر المواد الخام اس الم. تتضمن هذه الدراسة استخالص الحيوي مثال ذلك زيت الخروع والذي يعتبر من الزيوت غير الصالحة لألكل والتي توجد بكثرة في العديد من دول الع وزنيًا من هيدروكسيد البوتاسيوم %1زيت الخروع واستخدام االسترة القلوية المتجانسة لتصنيع وقود الديزل الحيوي. وقد تم استخدام عامل مساعد بتركيز من األحماض الدهنية. %0.7روع ووجد أنه يحتوي على نسبة في تصنيع وقود الديزل الحيوي. تم تحليل زيت الخ 6:1ونسبة الميثانول إلى الزيت المولية . اعتمدت في هذه الدراسة طرق االختبار القياسية للتحليل لتحديد خصائص وقود الديزل الحيوي. أشارت النتائج إلى %80بلغت انتاجية وقود الديزل الحيوي درجة مئوية. 15-، ونقطة الصب 54، والرقم السيتاني 3غم/سم 0.924افة كانت سنتستوك، والكث 14.24درجة مئوية كانت 40أن اللزوجة الحركية عند أظهرت النتائج أن وقود الديزل الحيوي من زيت الخروع عالي الجودة، مع رقم سيتاني مرتفع، ونقطة صب منخفضة للغاية. ــ ـــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ ــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ mailto:dr.alaa@kecbu.uobaghdad.edu.iq this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 19, no. 4, december, (2023) p. p. 7889 pdf comparison based on various fso channel models under different atmospheric turbulence mahdi a. atiyah* lwaa faisal abdulameer** gaurav narkhedel*** *,**department of information and communication/al-khwarizmi college of engineering/ university of baghdad/ iraq *** school of electronic and communication engineering/ dr vishwanath karad mit world peace university/ india corresponding author*email: mahdi.abd2103m@kecbu.uobaghdad.edu.iq ** email: lwaa@kecbu.uobaghdad.edu.iq ***email: ggnarkhede9@gmail.com (received 9 april 2022; accepted 28 september 2023) https://doi.org/10.22153/kej.2023.09.004 abstract recently, wireless communication environments with high speeds and low complexity have become increasingly essential. free-space optics (fso) has emerged as a promising solution for providing direct connections between devices in such high-spectrum wireless setups. however, fso communications are susceptible to weather-induced signal fluctuations, leading to fading and signal weakness at the receiver. to mitigate the effects of these challenges, several mathematical models have been proposed to describe the transition from weak to strong atmospheric turbulence, including rayleigh, lognormal, málaga, nakagami-m, k-distribution, weibull, negative-exponential, inverse-gaussian, g-g, and fisher-snedecor f distributions. this paper extensively studies and analyses different probability density functions (pdfs) that govern the fso channel, considering various channel models. this paper aims to comprehensively understand how fso channels can be effectively modeled using different pdfs. accurate modeling is crucial for designing fso systems that can operate optimally under potential environmental conditions. selecting the appropriate pdf model plays a crucial role in determining the fso channel's performance during system design. with a multitude of pdf models available, this study aims to identify the most effective pdf model to be employed in fso channel modeling. keywords: atmospheric turbulence (at), fisher-sedecor f, fso, gamma-gamma(g-g) lognormal(ln), pdf. 1. introduction high bandwidth, speed, low power usage, and virtual reality are some of the increasing connectivity requirements that 5g should have to address [1]. fso is a promising candidate to meet the requirements of high capacity and sufficient speed in 5g and beyond. however, line-of-sight (los) is essential in implementing the fso link. therefore, planes and trees are considered obstacles and limitations. in addition, atmospheric turbulence (at) ( fog and rain) mainly affects the quality of fso [2]. since device-to-device (d2d) enables direct connections without requiring a foundational management network. (d2d) is a leading candidate to meet the requirements of the fifth generation [3]. in addition to improving system security, fso's use of an unlicensed optical frequency allows for its operation. fso is a form of airborne broadband communication that involves the transmission of coherent visible or infrared light. [4] high-spectrum efficiency in wireless optical communication was improved by employing the (mimo) technique. [5,6]. accuracy and simplicity of complexity are essential in achieving beneficial results in knowing the effects of the channel on the fso binding[7]. mailto:mahdi.abd2103m@kecbu.uobaghdad.edu.iq mailto:ggnarkhede9@gmail.com https://doi.org/10.22153/kej.2023.09.004 https://doi.org/10.22153/kej.2023.09.004 mahdi a. atiyah al-khwarizmi engineering journal, vol. 19, no. 4, p.p. 7889(2023) 79 fig. 1. environmental of fso with ats. atmospheric effects and pe represent the biggest challenge to the quality of communication. scintillation occurs due to air turbulence, a wellknown issue connected to the channel's weather. moreover, the efficacy of the link is greatly affected by spatial jitter, which occurs due to occasional misalignments between the transmitter and the receiver. the term for this is pe [8]. a pdf distribution is also impacted by the aperture averaging effect, which tends to lessen the harmful impacts of scintillation and turbulence [9]. 2. related work for fso-based data transmission between two devices, los is required. the optical signal is significantly affected by attenuation caused by weather conditions, and its effect increases with the distance between the two devices [10]. it is a fundamental challenge with significant implications for the design of fso links [11]. to reduce the bit error rate (ber) of the fso link in opposite ats. in a fos link, electric fields in the atmosphere affect signal transmission. [12]. scintillation caused by intensity and phase changes in the channel is the main source of noise in an fso communication system. the pdf of the received irradiance of the optical field satisfies design parameters like detector threshold level, probability of detection, mean fade time, number of fades, and snr [13]. the main factor in determining at strength is the air's refractive index structure parameter (cn 2) [14]. see figure 2. fig. 2. challenges encountered in fso system. the turbulence is differentiated into three cases: weak (𝐶𝑛 2 = 10−17𝑚−2 3⁄ ), moderate (𝐶𝑛 2 = 10−14𝑚−2 3⁄ ), and strong (𝐶𝑛 2 = 10−13𝑚−2 3⁄ ). the combination of the transmitted light signal and the atmospheric channel impulse response is the signal that is taken by the receiver. the consequences of channel distortion are examined using the impulse response. [13] many basic models are proposed in the channel characterization of fso communication by analyzing system parameters and inferring what is observed in the pdf value. the rayleigh distribution was used to model the fso communication channel, which was analyzed and verified experimentally using pdf for weak at [15]. the fading associated with the weak atmospheric turbulence regime is typically modeled using the log-normal distribution [16]. in [17], the atmospheric environment and pe are essential factors in fso connection quality limitations. g-g is used to investigate fso channel parameters with pointing errors. a g-g distribution has been used to characterize fso connectivity among ats to evaluate system performance for moderate turbulence [18]. the efficiency of an fso channel was compared (in 2019) using the g-g and negative exponential (ne) models[19]. the authors of [20] have recently proposed a new fishersnedecor (f model) turbulence distribution model to characterize at over fso interconnections. also, in [7], an f model is proposed in the characterization of channel perturbation in fso communication. compared to the ln and g-g models, the proposed f turbulence distribution model in [2] mahdi a. atiyah al-khwarizmi engineering journal, vol. 19, no. 4, p.p. 7889(2023) 80 better matches experimental data for all turbulence conditions. furthermore, the f turbulence distribution is mathematically more straightforward than other distributions, such as the g-g, ln, and m distribution, because the pdf of the f distribution contains fundamental elementary functions analyzing fso communication systems. f model can analyze the fso system under various disturbance conditions. the málaga (m) distribution is more general in describing various perturbation states of the channel when steering errors are considered a robust statistical model in the expression. in contrast, distribution models such as the natural logarithm, g-g, and k distribution describe weak, medium, and strong perturbations. in [21], closed expressions are provided for the rate code error and potential outage. the m distribution is used in [22] to simulate the fso channel. the surface radiation fluctuation of infinite optical signals is described by a statistical model that has gained prominence recently. m distribution is a thorough model considering all at, from weak to strong disturbances. although the m distribution can model weak-to-strong at fluctuations, it is less capable of arithmetic tracking, as it is more complex than the g-g model. [23] in [24], weibull distribution was used to evaluate the performance of fso under water and proved that it has a high ability to correspond with the experimental results of the simulation. in [25], the f distribution was used to analyze a combined millimetre wave (mm-wave) and fso system with appropriate channel parameters. although the f model is the most suitable and traceable due to its computational availability for modeling the fso communication channel compared to the g-g model. it was considered the simplest mathematically in terms of complexity. [2] however, the g-g model is the most convenient and widely used because it works in all types of ats. the f model was applied on a double-hop fso channel with the g-g model, and the simulation obtained almost identical results for both models. [26] the pdf tails mostly determine the precision of signal recognition and fading probability [15]. the received irradiance pdf is nonstationary and is highly dependent on atmospheric turbulence factors. nonetheless, an exact pdf of the received irradiance is required to construct a robust and dependable fso communication system. in the next section, the channel analysis of the proposed selects the best suitable model under different conditions depending on the simulation results. 3. system and channel model any modeled channel is based on atmospheric turbulence. in fso communication, the channel is considered an atmosphere. by changing important factors like beam divergence, modulation techniques, mimo techniques, future ultimately, etc., constructing a more effective fso system can help to increase bit rate, transmission distance, and gain[16]. 3.1 rayleigh distribution the rayleigh (r) distribution was used to analyze the channel gain in fso communication by extracting the pdf value. it was observed that the scintillation index is 1. the density function of the r-distribution is more concentrated at low values. [13]. the pdf of the r distribution is given as: p(io)rd = 1 σr 2 exp ( −io 2σr ) , io > 0 … (1) where σr 2 is the rytov variance. 3.2 lognormal and gamma-gamma distributions the feeble regime of at is described using an ln distribution model. however, the g-g distribution model is also presented to characterize the turbulent channel, as it has been demonstrated to provide high accuracy under moderate-to-strong conditions. [27]. the ln model is the most popular at model because of its comparatively straightforward shape [9]. scintillation is the temporal and spatial fluctuation of light intensity induced by turbulent atmospheric conditions. when normalized, the scintillation index is defined as the variance of the light wave intensity [14]. according to [27], the half peak of the light intensity (𝐼𝑜) is an identically distributed gaussian random variable with a mean zero and a variance σo 2. by pdf of an ln distribution can be expressed as: p(io)𝐿𝑁 = 1 io√2πσo 2 e (− (ln io+ σo 2 2 )2 2σo 2 ) … (2) where 𝜎𝑜 2 (rytov variance) can be calculated as: [14] σo 2 = 1.23cn 2k 7 6d 11 6 … (3) where k = 2n λ⁄ is a wave number, λ is the and d is the link ,of the transmitterwavelength distance [28]. under signal transmission in moderately strong conditions, the pdf of the g-g model can be expressed as: [27] mahdi a. atiyah al-khwarizmi engineering journal, vol. 19, no. 4, p.p. 7889(2023) 81 p(io)𝐺𝐺 = 2(αoβo) αo+βo 2 γ(αo)γ(βo) . 𝐼𝑜 𝛼𝑜+𝛽𝑜 2 −1𝐵𝛼𝑜−𝛽𝑜 (2(𝛼𝑜𝛽𝑜𝐼𝑜)0.5) … (4) where γ(. ) gamma function, bi(. ) is a bessel function of the second kind, and in the i-th order, 𝛼𝑜 and 𝛽𝑜 are the effective turbulence at small and large scales as: [14] αo = [exp ( 0.49 σo 2 (1+1.11σo 12 5 ) 7 6⁄ ) − 1] −1 … (5) βo = [exp ( 0.5 σo 2 (1 + 0.69σo 12 5 ) 5 6⁄ ) − 1] −1 … (6) the complexity of the expression pdf of g-g for meijer's g function [27]. in [15], the pdf of gg provides a better fit for experimental results. table 1 shows a comparison of gamma values for various levels of air turbulence. table 1, comparison of g-g values for different ats. 3.3 nakagami-m distribution the nakagami (n) -m distribution channel is a versatile statistical mode that ranges from weak to strong. a probability density model connected to the g-g distribution is the n distribution. the n channel model performs better than the rayleigh model due to two parameters: the shape parameter m and the regulating spread ω [15]. the pdf for the nakagami fading model is given by: p(io)nd = 2mmio 2m−1 γ(m) exp ( −mio 2 2ω ) , io > 0 … (7) where γ(m) is the gamma function, m is the particle’s shape parameter, (m ≥ 0.5), ω is used to control the spread of the distribution, ω =e {𝐼𝑜 2 } m = e2{io 2} e{[io 2 − e(io 2)]}2 … (8) 3.4 málaga m distribution a pdf representation of the optical radiation distribution across the malaga canal in the fso link can be represented as follows: [29] p(io)m = ϑ ∑ αof(io) αo+f 2 βo f bαo−f (2√ αoiof pf + η ) … (9) ϑ ≜ 2(αo) αo 2 (p)1+ αo 2 γ(αo) ( p f p f + η ) f+ αo 2 … (10) 𝛼𝑜𝐹 ≜ (βo − 1 f − 1 ) (pf + η)1− f 2 (f − 1)! ( η p ) f−1 ( αo f ) f 2 … (11) where p, f, and 𝜂 are the average power of the scattering component, the value of the fading parameter, and the average power of the los component, respectively. 3.5 negative exponential distribution one more model that has gained widespread acceptance for use in the simulation of highly turbulent environments is the negative exponential (ne) distribution. this model, in conjunction with the rayleigh distribution, is primarily used to test experimentally when there is an amplitude variation across the turbulent medium in the saturation area with regard to irradiance. this distribution's pdf file has been assigned as : [30] p(io)ne = 1 io exp ) , , io > 0 … (12) where e{𝐼} = 𝐼𝑜 the mean of the receiver optical irradiance. 3.6 inverse-gaussian distribution inverse-gaussian (i-g) distribution is modeled as an alternative to ln distribution and is usually utilized for weak atmospheric turbulence conditions. the i-g channel model's pdf is as follows [31]: p(io)nd = √ λ 2π io −3 2⁄ exp ( −λ(1−μ)2 2μ2io ) , io > 0 … (13) where λ>0 is the distribution scale parameter and µ > 0 parameter of mean fluctuations. 3.7 k-distribution the k-distribution was used to model a severely weathered communication channel in the fso link [29]. the exponential and g-g distribution models are combined to form the k distribution. when performance parameters weak turbulences moderate turbulenc es strong turbulences σr 2 0.3 1.5 3.4 βo 10.1 4.1 4.3 αo 11.6 1.8 1.5 mahdi a. atiyah al-khwarizmi engineering journal, vol. 19, no. 4, p.p. 7889(2023) 82 compared to the ne model, this model is most frequently utilized for conditions of significant air turbulence, and its practical findings are quite consistent with its theoretical predictions. a search was performed on fso communications implemented through atmospheric disturbance channels for the distribution of k and it has been demonstrated that an accurate approximation of the pdf of the k distribution can be obtained by summing a limited number of weighted negative exponential pdfs as: [33] p(io)k = 2αo αo−1 2 γ(αo) io αo−1 2 bαo−1(2√αoio), io > 0 ...(14) when β is unity, the g-g distribution reduces to k-distribution. likewise, the kdistribution tends to ne distribution when 𝛼 ∞ [34]. 3.8 fisher–snedecor f distribution the channel gain for the fso link is modeled as: h = hplhathpe … (15) where hpl , hat , and hpe are deterministic propagation loss, at attenuation, and pe, respectively. a pdf of atmospheric turbulence can be represented for both links as: [26] fhat(x) = γ(α + β)αα(β − 1)βxα−1 γ(α) γ(β)(αx + β − 1)α+β … (16) where 𝛼 and 𝛽 are two variables that are the internal and external measures of disturbance, respectively. hence, they have an important role in affecting the optical propagation properties of the link, where α = 1 exp(σinn 2 )−1 … (17) β = 1 exp(σinm 2 ) − 1 + 2 … (18) where, 𝜎𝐼𝑛𝑛 2 and 𝜎𝑚 2 are the small-scale and large-scale log-irradiance variances, respectively, where 𝜎𝐼𝑛𝑆 2 can be expressed as: σinn 2 = 0.51δsp 2 (1 + 0.69δ sp 12 5 )−5/6 1 + 0.90d2( σ δsp )12/5 + 0.62d2σ12/5 … (19) where 𝛿𝑆𝑃2is the spherical scintillation index (ssi) of the fso link, σ2 represents the strength of irradiance fluctuations, and 𝑑 is the equivalent aperture diameter. such turbulence [26]. moreover, 𝜎𝐿 2 can be expressed as: σm 2 = σm 2 (l0) − σm 2 (l0) … (20) where σm 2 (i0) and σinm 2 (l0) are the inner and outer large-scale log-irradiance variances, the line-of-sight path for d2d communication is critical in maintaining a reliable wireless optical communication link. therefore, the dangers that may occur due to the movement of the source or interface or the deviation of the path is taken into account. that causes optical beam routing errors and data loss. in addition, the pdf of the pointing error can be expressed as: fhpe (x) = ℇ2 aℇ2 yℇ2−1, 0 ≤ y ≤ a … (21) where the a is a fraction of power at the receiver. here, ℇ = 𝜔𝑧𝑒𝑞 𝜎ℇ , where 𝜔𝑧𝑒𝑞 and 𝜎ℇ are the beam-width and the pe displacement standard deviation, respectively. the pdf of the instantaneous snr is represented as follows over the fisher–snedecor f composite fading channel: [35] p(io) = ηmρm−1 be(m, n)(ηρ + 1)m+n … (22) where η = m (n−1)p the multipath fading intensity is denoted by m and n values. denotes the shadowing shape parameter, 𝑝 is the average snr, and be(·, ·) denotes the beta function. 4. kullback–leibler divergence the congruence between the mathematical analysis and the actual experimental data observed among [9] of these pdfs is a necessary factor in choosing the most appropriate distribution for channel modeling, as well as the computational complexity factor, which is the main point of this paper. the best pdf is determined to be the one with the least amount of spacing to kullback–leibler divergence (kld) metrics [9], which enables a performance metric to be computed for each candidate pdf. kld is most helpful for application in a real-world dataset from a practical standpoint because it directly provides specific outputs that make it possible to scan any pdf file. kld is a way to gauge how close two probability distributions are. let p1 and p2 be two distinct distributions defined on the same probability space, where p1 is a theoretical probability distribution and p2 is measured against an experimental kld between two distributions is given as: dkld(p1||p2) = ∑ p1n log2 p1n p2n n …(23) mahdi a. atiyah al-khwarizmi engineering journal, vol. 19, no. 4, p.p. 7889(2023) 83 fig. 3. the kullback–leibler divergence values. the best result we want to achieve is that the convergence between p and q occurs when kld decreases. and the kld is non-negative and asymmetric in p1 and p2 [9]. the results from figure 3. indicate that the distribution of ln is the worst in agreement with the experimental data (dkld = 1.09 × 10−1), then it is followed by g-g. on the contrary, when the value of kld approaches zero, the burr distribution is the best among them ( dkld = 2.77 × 10−2) followed by the weibull distribution. despite the importance of kld in selecting the most appropriate channel distributions based on the pdf for each distribution, we focused on choosing the model with the least computational complexity. it should be noted that we pay attention to the design of the model and the amount of its estimation of the various channel disturbances. although the burr and weibull model is the closest to matching, the f model is the most accurate, least complex, and sequential in mathematical terms, similar to the ln, g-g, and m distributions, as it was proven in [23]. 5. numerical results and discussions this section analyzes the efficacy of the pdfs through simulations. to compare the effectiveness of models for fso channels under different ats. since atmospheric turbulence strongly affects the fso channel, channel modeling is necessary to match it in simulation. we do not have a guarantee of the stability of weather fluctuations, as they are likely to change at any moment. therefore, pdf models require accuracy in an arithmetic expression, simplicity in analysis, and obtaining satisfactory results that match the reality of simulation to ensure reliable results for choosing the most appropriate model for fso channel modeling in different channel conditions. figure 4 displays the log-normal pdf versus logirradiance variance for various values. σo 2 the distribution becomes more lopsided as the value of σo 2 increases, with longer tails extending in an infinite direction. we chose three values of σo 2 (0.2, 0.5, and 0.8). this indicates the degree to which their fluctuation changes as the channel inhomogeneity continues to increase. according to figure 5, there are three different levels of turbulence: weak, moderate, and strong. the figure demonstrates that as the turbulence increases from the weak to the strong regime, there is a corresponding increase in the range of potential values of the irradiance. the distribution becomes more spread as a result. the results are shown in fig. (6 and 7) for channel parameters g-g distribution, where the simulation was done assuming strong and medium turbulences. in addition to a distance of 4500 meters between the transmitter and the receiver at λ =1550e-9. under strong turbulence, the amount of radiation at a distance of 1840 meters is 30.73db, and this amount decreases as the distance of the fso connection increases due to the attenuation of weather conditions affected by an amount change in the refractive index, as it is 35.36db at approximately 5514 meters. we noticed (fig. 7) the g-g model under almost medium conditions, the signal radiation is -5.21db at a distance of 1741 meters. now, it is clear to us from (fig 6,7) that weather conditions have an essential and sensitive impact on the design of the fso link, which requires accurate modeling in estimating the system parameters. in figure 8, a lower standard deviation results in a narrower distribution. when the values of the variable irradiance become closer to the mean, there will probably be less variability. therefore in fig.9, a large value of m close to 1 is tested in the nakagami-m distribution, and signal crossovers are reduced, resulting in a more stable channel with less deep fade. as a result, nakagami-m model has become more similar to an r distribution where we look at the f distribution (fig. 10), and we find that it approximates the radiation distribution to the g-g distribution within different magnitudes of the channel parameters. this is what suits us in choosing the most appropriate mathematical analysis in line with different weather conditions. mahdi a. atiyah al-khwarizmi engineering journal, vol. 19, no. 4, p.p. 7889(2023) 84 in figure 11, the increase in the irradiance values of ne distribution produces a greater degree of fluctuation in the channel coefficients, which in turn leads to an increase in the turbulence level. in figure 12, the simulation results for various values of the 𝜎 parameter are presented. as it can be seen, the performance improves as the value increases. after conducting mathematical analysis and simulation, it was found that each distribution has its own characteristics that distinguish it in terms of channel parameters, the intensity of disturbance, the accuracy of matching with experimental reality, and computational complexity in modeling the fso channel. we found that r, ln, i-g, n, ne, and k distributions are not suitable for channel different conditions, though accurate and appropriate to certain circumstances. as for the gg and f distributions, we consider them the most appropriate for achieving more benefit for modeling the channel under different conditions. fig. 4. pdf of lognormal distribution under weak at. fig. 5. pdf of gamma-gamma distribution under different ats. fig. 6. irradiance and distance of gamma-gamma distribution under strong a fig. 7. irradiance and distance gamma-gamma distribution under medium at. fig. 8. pdf of rayleigh (r) distribution. mahdi a. atiyah al-khwarizmi engineering journal, vol. 19, no. 4, p.p. 7889(2023) 85 fig.9. pdf of nakagami-m model. fig. 10. pdf of fishersnedecor f distribution. fig.11. pdf of k-distribution. a pdf was calculated for both distributions (gg and f) for different parameters under similar conditions, as in figure 13. in comparison to distribution 1, pdf 2 for both distributions has a somewhat smaller shape parameter, indicating a relatively lighter tail. if it is clear from the figure, the experimental correspondence in the curves between the (g-g and f) distributions, despite the slight difference, may not be effective in terms of practice. in summary, the ln model is not suitable for practice. although ln is very simple to distribute, when comparing the ln model to the observed data under weak perturbation conditions, it performs imprecisely in the tails of the pdf. although i-g the distribution is simple in mathematical representation. fig. 12. pdf of negative exponential (ne) distribution. fig. 13. correspond pdf of gamma-gamma and fishersnedecor f distributions. mahdi a. atiyah al-khwarizmi engineering journal, vol. 19, no. 4, p.p. 7889(2023) 86 the i-g distribution fits a value closer to the ln model than the g-g distribution model. the ne distribution and the g-g model have the same ranges, but the drawback of the former is that the optimal value occurs in the negative region. on the other hand, the main advantage of the g-g model is its ability to work well in situations where other channels struggle due to the effects of sub-channel correlation, even in cases of wide perturbation variations. in addition, regarding the g-g distribution, we find the expression complexity of the meijer function g, which generates additional computational complexity. however, it is suitable for potential conditions within the proposed system, which range from medium to strong, and we consider it to be the most suitable type for estimating channel parameters. also, the distribution of f is the simplest for the same expected results at the g-g distribution. 6. conclusions speed and high data flow are prerequisites for the current and later generations of communication systems. to meet this demand, communications fso has emerged as a primary candidate because of its ability to bypass frequency-related licensing restrictions, its relative ease of installation, interference reduction, and cost-effectiveness. however, the main challenge is maintaining connection reliability, primarily due to adverse weather conditions. various factors, such as luminescence refractive index and pes affect the performance of optical signals. to address these limitations, we performed an analysis of pdfs from different types of channel models used in fso communications to calculate channel states under different perturbations. pdf plays a critical role in testing the appropriate design of potential cores of fso systems. therefore, we considered common fso channel modeling distributions, such as rayleigh, lognormal, málaga, nakagami, kdistribution, negative-exponential, inversegaussian, gamma-gamma, and fishier f distributions. our analysis revealed that the ln, r, n, and i-g distributions exhibit simple mathematical and experimental properties, which makes them suitable for weak weather conditions. on the contrary, the m, f, and g-g distributions showed better performance under different conditions, especially under strong weather conditions. the m distribution, although empirically appropriate, has greater mathematical complexity. on the other hand, the f distribution showed the simplest mathematical analysis with satisfactory results. finally, the g-g distribution emerged as the most suitable choice among all species, performing well in all regimes, ranging from weak to strong turbulent regions. as a result, we recommend using the gamma-gamma distribution as a channel model for fso communications based on channel analysis using pdf distributions. this choice ensures robust performance and reliability under changing weather conditions. abbreviations at atmospheric turbulence ber bit error rate d2d device to device f fishersnedecor f fso free space optical g-g gamma-gamma i-g inverse-gaussian kld kullback–leibler divergence ln lognormal los line-of-sight n nakagami ne negative exponential m málaga mgf meijer’s g function mimo multiple input multiple output pdf probability density function pe pointing error snr signal to noise ratio ssi spherical scintillation index 7. references [1] mohammed jawad al-dujaili et al.,” fifgenerationtelecommunicationstechnolog ies: features, architecture, challenges, and solutions,” wireless personal communications volume 128, pages447–469 (2023). 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[30] akinchan das et al.,” free space optical links over málaga turbulence channels with transmit and receive diversity”, optics communications 456 (2020) 124591 [31] z. ghassemlooy, et al,” optical wireless communications system and channel modeling with matlab, crc press, ny, 2013. [32] sun, h. et al.,” computationally tractable model of energy detection performance over slow fading channels” ieee commun. lett. 14(10), 924–926 (2010). [33] s. tannaz et al.,” impacts of the negativeexponential and the k-distribution modeled fso turbulent links on the theoretical and simulated performance of the distributed diffusion networks”, journal of communication engineering, vol. 8, no. 2, july-december 2019. [34] hossein samimi et al.,” subcarrier intensity modulated free-space optical communications in k-distributed turbulence channels”, journal of optical communications and networking (volume: 2, issue: 8, august 2010). [35] aladeloba et al,” improved bit error rate evaluation for optically pre-amplified freespace optical communication systems in the turbulent atmosphere”, iet optoelectron. 6(1), 26–33 (2012) [36] weijun cheng, et al., “on the performance analysis of switched diversity combining receivers over fisher–snedecor f composite fading channels”, sensors 2021, 21, 3014. https://doi.org/10.3390/s21093014. https://doi.org/10.3390/photonics9070437 https://doi.org/10.3390/s21103454 https://doi.org/10.3390/s21093014 (2023) 78-89، صفحة 4، العدد19مجلة الخوارزمي الهندسية المجلد مهدي عبد عطية 89 مختلفة في ظل اضطرابات جوية مختلفةfso مقارنة دالة كثافة االحتمال بناًء على نماذج قناة لواء فيصل عبد االمير ** مهدي عبد عطية * ***غوراف نارخيدل *،**قسم هندسة المعلومات واالتصاالت / كلية الهندسة الخوارزمي / جامعة بغداد/ العراق الهند ا/جامعة السالم العالمي بمعهد ماساتشوستس للتكنولوجي /اإللكترونيات واالتصاالتكلية هندسة *** mahdi.abd2103m@kecbu.uobaghdad.edu.iq: البريد االلكتروني* lwaa@kecbu.uobaghdad.edu.iq:البريد االلكتروني** gmail.com9ggnarkhede@:البريد االلكتروني *** الخالصة لمجال الفضائي في اآلونة األخيرة، أصبحت بيئات االتصال الالسلكي ذات السرعات العالية والتعقيد المنخفض أمًرا أساسيًا. ظهرت التقنية البصرية في ا عُرضة لتقلبات fsoكحالً واعدًا لتوفير اتصاالت مباشرة بين األجهزة في إعدادات االتصال الالسلكي عالية التردد. ومع ذلك، فإن اتصاالت (fso) الحر نتقال من اال إشارة ناجمة عن الطقس، مما يؤدي إلى انحسار اإلشارة وضعفها عند المستقبل. للتغلب على هذا التحدي، تم اقتراح عدة نماذج رياضية لوصف و weibullو k-distributionو nakagami-mو málagaو lognormalو rayleighالتضخم الجوي الضعيف إلى القوي، بما في ذلك توزيعات negative-exponential وinverse-gaussian وg-g و fisher snedecor f في هذه الورقة، ندرس ونحلل بشكل موسع مختلف الدوال الكثافة بفعالية باستخدام fso، مع النظر في نماذج القنوات المختلفة. الهدف هو توفير فهم شامل لكيفية تصميم قنوات fsoالتي تحكم قناة (pdfs) االحتمالية pdfs المختلفة. النمذجة الدقيقة ضرورية لتصميم أنظمةfso أن تعمل بشكل مثلى تحت ظروف بيئية محتملة. اختيار النموذج الصحيح لل يمكنpdf المتاحة، يهدف هذا الدراسة إلى تحديد النموذج األكثر pdfأثناء تصميم النظام. من خالل العديد من نماذج fsoالذي يلعب دوًرا حاسًما في تحديد أداء قناة fso. قناة فعالية لالستخدام في نمذجة mailto:ggnarkhede9@gmail.com mailto:ggnarkhede9@gmail.com windows-based special applications router al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 5, no. 4, pp 69-98 (2009) windows-based special applications router omar a. athab* ahmed s. hadi* sufyan t. faraj** * information and communication engineering department/ al_khawarizmiengineering college/ university of baghdad ** computer college/ al-anbaruniversity (received 16 march 2008: accepted 17 august 2009) abstract the design and implementation of an active router architecture that enables flexible network programmability based on socalled "user components" will be presents. this active router is designed to provide maximum flexibility for the development of future network functionality and services. the designed router concentrated mainly on the use of windows operating system, enhancing the active network encapsulating protocol (anep). enhancing anep gains a service composition scheme which enables flexible programmability through integration of user components into the router's data path. also an extended program that creates and then injects data packets into the network stack of the testing machine will be proposed, we will call this program the packet generator/injector (pgi). finally, the success of the node architecture and its prototype implementation is evaluated by means of a few practical applications. keywords: active network, active router, user components, windows operating system, active network encapsulation (anep), packet generator /injector (pgi). 1. introduction "active networks allow individual user, or groups of users, to inject customized programs into the nodes of the network.”active" architectures enable a massive increase in the complexity and customization of the computation that is performed within the network, e.g., that is interposed between the communicating points." in traditional networks an intermediate node executes ordinary computations on packets. all packets are treated in the same way: nodes only forward packets towards the right destination. instead, an active node makes difference between packets. they contain programs that have to be executed on them. the difference between a traditional network (store-and-forwarding model) and an active one (store-compute-and-forwarding model) is that, in traditional network the delivery process is static, relatively passive, because all packets are treated individually. while in active network delivery process is dynamic, where the packets become smarts, i.e., they contain their own handling instruction that enable these packets to arrive, execute, and move to their destination [1]. a key characteristic of this technology is the ability to rapidly create, deploy and manage new network services in response to user demands. 2. literature survey since the focus of the work presented in this paper concerns the development of active node architecture, this section focuses primarily on completed works in active systems design. d. j. wetherall and d. l. tennenhouse have first pursued the idea of placing program fragments into internet protocol (ip) packets as part of the activeip project [6, 7]. initially, they studied the potential of placing small programs within the option fields of ip packets. these socalled active options, encoded in tcl [5] language in their prototype implementation, were executed by modified network nodes as the packets traversed the network. active node transfer system (ants) [8, 2], provides a capsule programming model. capsules are packets that encapsulate data with a customized forwarding code. applications use the omar a. athab al-khwarizmi engineering journal, vol. 5, no. 4, pp 69-98 (2009) 70 network by sending and receiving capsules via active nodes. when a capsule arrives at an active node, the type field is used for de-multiplexing to the corresponding forwarding routine, before the corresponding routine is executed to forward the capsule. ants provide active node application programming interface (api) calls to query the node environment. the demand-pull mechanism is used to obtain code from the previous node that the capsule visited. the ants prototype is implemented in java under unix operating system. the smart packets project [9], emphasizes particularly on applying active networking technology to network management. it aims at addressing scaling problems that are inherent in typical polled managed devices rather than aiming for general transport mechanisms such as ants. smart packets are encapsulated within anep packets and anep packets are encapsulated within an ip packet using a specific option (router alert). the smart packets architecture expects all programs to fit within one ethernet maximum transmission unit (mtu). there is no existing language that had a compact enough representation for smart packets environment. as a result, sprocket [10] and spanner [11] languages are developed as part of the smart packets project. switch ware active network architecture [12], consists of three layers: active packets, active extensions and a secure active router infrastructure. active packets carry programs consisting of code and data to replace both the header and payload of traditional packets. as a consequence, a new programming language for active networks, known as plan [13, 14], is designed and implemented. active extensions [15], which are not mobile, form the middle layer of switchware architecture. they communicate with other routers via active packets. it is programmed in caml. a secure active router infrastructure forms the lowest layer of switchware architecture. it provides a secure foundation on which the other two layers are built. secure active network environment (sane) [16] is designed to embody secure active router infrastructure. the role of sane is to ensure that the presumptions of the other system elements are true. mit's click [17] is software architecture for building flexible and configurable routers. a click router is "configured" from packet processing modules called elements. individual elements support simple router functions such as packet routing, queuing, or scheduling. a complete router configuration is defined by a directed graph whose nodes are the elements. a click router configuration is determined at compile time. the elements are internally represented by c++ objects that are inter-linked with each other through object references under linux os. packet passing between functional elements is thus simply a matter of passing memory pointers between objects. router plugins [18], aims to build a flexible network subsystem that offers the ability to select implementations (or even instances of the same implementation) of router components, called plugins, on a "per-flow" basis. plugins are binary code modules that can be dynamically loaded and unloaded into the router kernel at run-time. netbsd, which is used as the base platform for router plugins, provides appropriate kernel support to load modules into the kernel. the plugin control unit (pcu) provides the "glue" to bind individual plugins to the network subsystem. the application level active network (alan) system [19], introduces value added network services by means of an overlay active network infrastructure. the system is assembled from standard ip applications and servers connected to the internet. active processing "inside" the network takes place in so-called dynamic proxy servers (dps). the active programs, called proxylets [20], act as communication proxies for data streams dispatched through the dynamic proxy servers. alan requires the data streams to be explicitly addressed to the proxy servers. the current implementation, known as funnelweb [21], is based on rmi of java 2. the lancaster active router architecture version 2 (lara++) [22, 3] proposes an active router architecture. the key building blocks of lara++ are: the active nodeos, the policy domains, the processing environments, and the active and passive components. the active nodeos provides low-level system service routines and policing support to enable controlled access to node-local resources and system services. policy domains (pds) form the management units for resource access and security policies which are enforced on every active program executed within the pd. processing environments (pes) provide the protected environments for the safe execution of active code. active components (acs) are the units of active code processed within the pes. to assure platform independence, there are two prototype lara++ implementations for both ms windows and linux being developed. omar a. athab al-khwarizmi engineering journal, vol. 5, no. 4, pp 69-98 (2009) 71 3. work objectives this work primarily aims to get the following: 1. proposing architecture for active network system, regarding the available tools. 2. implementing a prototype for active router. 3. investigation of new techniques in the implementation. rather than standing in the old layering model in networking, a component-based approach was introduced. also, entering the challenge of in-kernel programming technique instead of the common user-mode approach. in addition to use a closed-source-code os "windows", which is rarely used in in-kernel network implementations. 4. paper layout section 5 presents the design of the active router (ar) architecture. this central part of the paper describes in detail how ar operates and how the component-based active node architecture enables network programmability through flexible integration and extensibility of network functionality. in addition to the basic node design, special focus is placed on the service composition framework. section 6 then describes the ongoing implementation efforts of developing prototype nodes of the ar architecture. due to the considerable extent of the ar architecture, this section focuses primarily on validating the key aspects of the design through a 'proof-of-concept' implementation. section 7 continues with a qualitative and quantitative evaluation of ar and its prototype implementation. it evaluates how the ar architecture satisfies the objectives and requirements. finally, section 8 concludes the paper by drawing together the main arguments of this work. it also describes further work that could be carried out based on this line of research. 5. ar architecture overview the overall architecture of the proposed active network has been divided into three functional parts: the component distributor (cd), the packet manipulator (pm) and the" proof-of-concept" part. the first part; the component distributor (cd),concern the transferring of user components from a privileged end-system (pes) or network administrator (admn) system to the active router (ar). the management of the transferred component is also the responsibility of the cd. in other side, the pm functional part extends the os networking stack such that it can intercept the in-bound packets that enter the ar and discriminate among the various types of packets. after distinguishing the type, the pm forwards the packet to the proper component to be serviced. the third functional part is dedicated for the proof-of-concept of the idea in this paper. it also contains the design and implementation of packet generator/injector (pgi) system. its main purpose is the construction and sending of two types of packets: active and traditional. the proposed architecture is designed to extend exiting routers by layering active networkspecific functionality on top of the router operating system. a generic high-level active network layer enables cross-platform programming and processing of active programs. low-level functionality of the ar architecture as provided by the active node operating system (nodeos) is directly integrated with the router os in order to maintain good performance for the active processing. the following sections explain in details the first two parts of the proposed ar, which there positions are also shown in fig. 1. the third part will be explained in section 7. 5.1. component distributor (cd) the proposed component distributor allows the user to load new components in the ar, where it is responsible for the fetching of user component (uc). fig.1. positions of the cd and pm units with respect to the windows layers of the proposed ar omar a. athab al-khwarizmi engineering journal, vol. 5, no. 4, pp 69-98 (2009) 72 the uc is a program performing either protocol processing or value-added function to the packet. the code of the uc is written by a privileged-end user (peu) or purchased from software third party, then sent from any pes to the ar using the cd unit. the ucs are distributed in the form of pre-compiled machine code. thus by using uc the ar is programmed individually through out-of-hand instantiation of active program. the uc is in the form of dynamic link library (dll) file. the cd unit provides the capability of reading, packing, and then transferring the uc from a pes to the ar. the second function of the cd is to upload the uc to the ar using a certain protocol; the file transfer protocol (ftp) [27]. the cd unit operates in a client/server fashion. the ar represents the server, whereas the pes represents the client. hence, jobs of the cd can be summarized as: packing, uploading, and controlling the uc. 5.2. the packet manipulator (pm) the packet manipulation begins with intercepting the packet and ends with forwarding it to the appropriate user component to be processed there. hence, in addition to catching a packet, the pm performs a light firewalling, lifting the packet from the kernel to the user mode, recognizing its type, and finally (if required) dispatching the packet to the user component that it whishes for processing. fig.2. block diagram of pm architecture. consequently, the pm architecture was further divided into the following functional units: the packet interceptor/injector (pij), packet filter (pf), packet bridge (pb), packet classifier (pc) and packet dispatcher (pd). it is noteworthy to state that the packet classifier and packet dispatcher are residing in the user-space of the ar. the packet bridging unit behaves as a channel between the user space units and the rest kernel space units (interceptor and filter). a simple block diagram of the designed pm is shown in fig. 2. the figure also depicts paths that may be taken by packets that passing the ar. the following sections illustrate the pm units briefly. 5.2.1 packet interceptor/injector (pij) the packet interceptor/injector provides the interface between the active network environment and the data path on the node. the packet interceptor (pi) is responsible for intercepting the network traffic traversing the node and passing it to the active network environment for processing. the packet injector (pj), by contrast, re-injects the network data back into the default forwarding path on the node or sends it directly through one of the outgoing interfaces. fig.3. simple diagram of the proposed skeleton im driver (pij unit). a network driver interface specification intermediate (ndis im) network driver was proposed to realize the pij under windows 2000 os. we choose omar a. athab al-khwarizmi engineering journal, vol. 5, no. 4, pp 69-98 (2009) 73 this driver in this paper because it’s well documented and it’s in excellent location in the stack, which will gives a lot of control over network packets without affecting other network protocols in the stack. a simple diagram of the proposed skeleton im driver (pij unit) is shown in fig. 3. the proposed pij can be loaded (or unloaded) dynamically at run-time (without interrupting the entire system). this allows the ar to dynamically activate (and de-activate) the active network functionality on a node. note that removing the packet interceptor completely disables any ar specific processing on the data path. 5.2.2 packet filter (pf) the proposed project provides a programmable pf on the read handle. the pf introduces a list of network source/destination address ranges and an "action" to be performed on packets that match the firewall criteria. the actions are: block: have the pf drop the matching packet from the normal packet flow. pass: have the pf allow the matching packet to pass up to the pt driver as in the normal flow. read: have the pf pass a copy of the received packet to the packet bridge which is the next unit in the ar. 5.2.3 packet bridge (pb) the paper establishes so-called packet bridge to provide the means to transfer network data to and from the uc. the pb unit targets to facilitate the interface between the kernel and user sides of the pm. hence, pb consists of modules in both the kernel and the win32 application sides. it is noteworthy to recall that the pij and pf units are placed within the kernel space of the proposed ar. however, to make the system more flexible it is suggested to load the ucs in the user space of the os. 5.2.4 packet classifier (pc) at this point a copy of complete packet has been captured and reached the pc. the object of the pc is the discrimination among the various types of packets that may pass through the pm. 5.2.5 packet dispatcher (pd) the pd defines the "route" through the uc space for the active data packets (adps) passing a node. the pd plays a central role in the service composition process. it determines based on the set of component identifier (cid) in service composition field of the anep header which uc(s) are involved and in which order they should process the adp. after the uc(s) finished it's processing on the adps, the pd returns the packet back to the windows network stack through the pb. the pb, in turn, either injects the packets into its previous default forwarding path (virtual adapter) on the node or sends it (lower adapter) directly through one of the outgoing interfaces. if the adp is re-injected to the virtual adapter, the routing operation is applied. it is performed strictly like the conventional routers. 5.3. service composition a composite service [28] is constructed from a set of components by means of a composition method. the composition method determines the set of software components needed to compose a service and the bindings to join these components. a pd is designed to associate active data packets (adps) passing an active node with the appropriate active extension (or uc). for this reason, anep [4] has been proposed as a means to assign packets passing a network node to active computations. 5.3.1. enhancing anep the basic anep header [4] specifies a 16-bits field for the type identifier (id) of a single executing environment (ee) that must process the adps in the ar. but, in this paper, the concept of component-based services is envisaged to achieve a good flexibility in introducing functionalities for the adps. this means that we have either multi-execution environment (where each one represents a single component) or single ee (contains all installed ucs). in the two assumptions there is a limitation in determining which components(s) and in what order are appropriate to process the adps. according to the basic anep header, the type id field in the entering adp can assign only one component to process the packet. this is a big restriction. this will restrain the ar to be really active and flexible. furthermore it may weak or omit the principal of component-based services in the ar; services that require more than one component can not be achieved in such fashion. therefore, two proposals are presented below to enhance the original anep to overcome this limitation. omar a. athab al-khwarizmi engineering journal, vol. 5, no. 4, pp 69-98 (2009) 74 5.3.1.1. anep proposal 1 using the same anep structure but with giving a unique type id not only for each single components but also for each combination of 2 or more components with various sequences. for example, if there are two components (namely a and b) installed in the ar, the coding of the type id field, to assign one of them or both, appears as in table 1. the statement (a then b) that appears in table 1 means that the active packet like to enter component “a” processing first and then component “b”. it is a simple service composition method. however, the same context can be followed for three or more components. table 1, type id coding of active component for proposal 1. component name type id a 1 b 2 a then b 3 b then a 4 5.3.1.2. anep proposal 2 in which the type id field is not used to indicate exactly the uc, instead it is exploited for indicating the count of ucs that may be composed to introduce the service to the active packet. the component id (cid) of the component itself is described in a new proposed variable-length field which we call "service composition" field. it is placed after the basic header and before the options field. this new field consists of the cids of the components that must be composed to create the required active service. fig.4. format of anep proposal 2. the order at which the cids appear in the service composition field is considered as the sequence of the components that will be composed in the active network node. the proposed anep format is shown in fig. 4. using this format, the lack of service composition capability in the original anep can be avoided.  service composition field format the proposed format of the service composition field is shown in fig. 5. it is divided into subfields, each one contains a cid of the component to be processed and its length is 16 bits. conceptually, the count of components that can be assigned in the service composition field is bounded by the count of component (cc) field value, which is not exceeds 2 16 as maximum edge. fig.5. format of "service composition" field. at a first glance, one may think that the 16-bits long component id field of each component will cause a large overhead on the system, especially if there are a large number of components required to be composed to provide the suitable processing for the packet. however, this is not true, because normally the components that need to be composed may not exceed about 10 components (i.e. about 20 bytes overhead only out of 1500 bytes long for ip protocol packet). 5.3.2. discussion  proposal 1 advantages 1functionality better than the original anep format since it provides a single and multicomponent service composition with controlled order. 2relatively, no additional processing time needed over the original anep since the same fields are used. disadvantages 1type id range available to identify components is decreased because of the range that is wasted in covering the multi-component service composition ids with various ordering. 2the active components and the composed services are offered by the active node designer or administrator and not the active network user who construct the active packet. the active node designer, for any reason, may not offer all the probabilities of services that may composed by different components or he may impose a charge for specific services. this might represent a contradiction with 0 15 16 31 version flags component count anep header length anep packet length service composition options payload 0 15 16 31 1st component id 2nd component id 3rd component id ………. …………… ………… ………… omar a. athab al-khwarizmi engineering journal, vol. 5, no. 4, pp 69-98 (2009) 75 the idea of active networking that depend on, as long as possible, moving the programmability from the active node administrator to the privileged users for more flexibility.  proposal 2 advantages 1like in anep proposal 1, it has functionality better than the original anep format since it provides a single and multi-component service composition with controlled order. 2it keeps the wide range of type id field by providing 16-bit field for each single component in the service composition field. this property supports the component-based principal of the network node by keeping the capability of building different useful services by small program components. 3the peu (or the packet producer or installer) himself would be the composer of the services and not the active node designer or administrator. this evidenced that the end-user is the first beneficial of the active network idea. disadvantages 1the overhead is more than both the original anep and proposal 1 formats because of the additional service composition field. 2it requires more processing time than both the original anep and proposal 1 formats because of the new appended service composition field and the cc field. a brief comparison among the original anep format and the two proposals for enhancing anep is shown in table2. table 2, brief comparison among anep, anep proposal 1 and 2. anep proposal 2 anep proposal 1 original anep function single and multiple component services single and multiple component services single component services services component 1 better functionality better functionality fair functionality functionality 2 require more processing time than the original no additional processing time required the original anep processing time processing time 3 wide type id range type id range less than original wide type id range type id range 4 services are flexible because it is fully controled by the end user services are flexible but offered by the active node administrator services are restricted because it depends on single component flexibility of services 5 overhead is large thab the original similar to the original bit overhead original bit overhead bit overhead 6 5.3.3. conclusion according to the above discussion, it is evident that proposal 2 for enhancing the basic anep header is preferred. therefore, proposal 2 will be adopted throughout the work presented in this paper. one of the contributions, of the proposed ar is the novel service composition scheme for active services. 6. ar implementation this section describes the ongoing efforts to engineer a prototypical realization of the proposed active router (ar) architecture. 6.1. component distributor implementation 6.1.1. cd server the cd server is implemented using the ftp omar a. athab al-khwarizmi engineering journal, vol. 5, no. 4, pp 69-98 (2009) 76 server provided by windows os. the ftp service is available already but not activated. to activate this facility, information services (iis) in the add/remove windows components dialogue must be chosen. in the internet iis dialogue; the ftp service should be selected. the default folder used to cache the ucs in the ar is located in c:\inetpub\ftproot. any ftp client can, till now, only visit this folder, but it can not read or write files on it. to enable the read and write on ucs in the ftp root folder, the read and write boxes must be checked in the home directory of ftp server properties. the ftp server properties can be reached from iis service in the administrative tools within the control panel. 6.1.2. cd client the cd client in the pes side is realized by exploiting the ftp client capability which is available in with the internet explorer under windows os. peu can display the two side screens (ftp client and server) in his workstation. the ftp client in the pes side is realized with the internet explorer under windows os. while the ftp server is realized by inserting the ip address of the target ar in the address bar preceded by ftp acronym to connect to the ftp server. ucs can be uploaded easily by drag and drop from the pes screen to the ar screen. peu, also, can control (delete partially or completely and rename) the installed ucs in the ar. but this control capability obeys the previous configuration of the ftp server. 6.1.3. structure of uc the proposed uc is implemented as two files: code and configuration files. code file contains the source code required to process the adp actively to enforce a certain protocol or achieve a value-added function. the code should be written in high-level language support microsoft visual studio application programming interfaces (apis). in this paper, c++ language is used to program the source file. concerning the code file of uc, peu can either upload it as it is (source code file) or convert it to a dynamic link library (dll) file. in this implementation, only the latter case is adopted. dll is a module contains function(s) and data. a dll is loaded at run time by its calling module. when a dll is loaded, it is mapped into the address space of the calling process. dlls can define two kinds of functions: exported and internal. the exported functions can be called by other modules. internal functions can only be called from within the dll where they are defined. although dlls can export data, its data is usually only used by its functions. the second part of the expected uc is the configuration file. actually, it is an initialization (ini) file that contains configuration data (i.e. idiom terms) for microsoft windows based applications. it allows a program to store initialization data, which can then be easily parsed and changed. “ini” files are used to store configuration information for applications programs. to provide more flexibility for peu, in this project the “ini” file is created using simple c language routine. the file consists of only a single c-language structure (servlnfo structure). this structure, in turn, contains the name of code file of uc (the .dll file name) in a string format and a control buffer with its length. the control buffer is involved for configuration purposes (if required). 6.2. packet manipulator implementation the pm is implemented using im driver (in the kernel space), the pc and pd units are realized in the user-space as an extension of the driver. 6.2.1. im driver the foremost and significant step in realizing the pm architecture is the implementation of a simple "pass through" im driver. a "pass through" (or passthru) driver means a do-nothing pass-through im ndis driver. it abstractly performs the basic principles of initializing and setting up an im driver. this driver exposes a virtual adapter for each binding to a real physical adapter. in turn, the overlying protocol drivers can bind to these virtual adapters as if they are real adapters. however, the passthru driver has been implemented as six software modules: main, adapter, ndisreq, recv, send and status. in addition, there are other auxiliary modules that are related to power management of the driver such as the reset and shutdown states and the plug and play (pnp) capabilities. the following subsections briefly discuss the developed passthru driver modules. the routines of these modules may require prior knowledge of ndis drivers' development: a) main module: this module consists of the routines that load the passthru driver and initialize its driver-wide data structures and resources. in omar a. athab al-khwarizmi engineering journal, vol. 5, no. 4, pp 69-98 (2009) 77 addition, the main module register and de-register the input output control (ioctl) interface and the device object that are used by the user-mode applications to communicate with the im driver. b) adapter module: the adapter module functions are called by the ndis wrapper, for example to allocate and de-allocated a passthru virtual adapter instance, to halt or shut down the driver upper edge, to query information about the capabilities of the passthru and to request the driver to bind (or unbind) to an underlying mp nic driver. also there are routines capable to allocate and deallocate a context pool to be used for exchange of data between the adapter and the applications. c) ndisreq module: mainly the functions of this module related to ndis requests to the passthru driver. ndis may query information about the status of the im or request changes in the state information that the passthru maintains. each ndis driver contains its own management information block (mib) [23]. it is an information block in which the driver stores dynamic configuration information and statistical information that higher-level drivers or applications can query or set. d) status module: status notifications initiated by the underlying nic mp driver are indicated using functions of this module. e) send module: ndis calls the functions of this module to transmit a single (or multi) packets to the underlying nic driver. then, ndis also indicates the completion of the send operation to the im driver. f) recv module: after the underlying nic driver indicates a received packet to the wrapped ndis, the ndis in turn indicates this packet up to the passthru driver by calling the functions of the recv module. two standard functions were written to receive the indicated packet (as recommended by driver development kits (ddk) documentation). these are the ptreceivepacket and ptreceivelndication functions. the two functions must be exposed by the passthru driver to the underlying mp driver. nevertheless, it may not be easy to guess which one the ndis will decide to use. in either case, the passthru performs the minimum manipulation here to just forward the packet up to the overlying pt driver. exposing the two receive functions is mandatory. it is important to be noticed that the routines mentioned above are only the essential routines that must be included according to microsoft ddk documents [23]. 6.2.2. pij unit the implemented passthru im driver simply passes the packet data along without modification. also, this driver stops short of actually illustrating any observable function. to be of any actual use, the developer must take the next step and add functionality of his own to the implemented skeleton driver. also, the passthru driver requires an accurate tracking to get a copy of a complete received packet. in addition, when gaining a copy of a packet it may be needed (after processing, if any) to re-inject the packet again into the im driver to complete its passage up in the networking stack. as stated in recv module, ptreceivepacket function or ptreceiveindication function may be called by ndis to indicate a received packet. internal considerations in the operating system determine which one is used. other crucial considerations such as avoiding interrupting with windows normal activities and take care in allocating and de-allocating of memory storage areas must also be taken into account in the pij implementation. however, two approaches are available in pij realization (or extending im driver, in general). the developer either enforces the above step-by-step (manual) implementation or using a cloned packet approach. the cloned-packet approach has been realized by adding a smart module called util module, which support recv module. util module consists of routines deal with allocating and de-allocating packets, memory, and buffer descriptors, and tracing the packet path in the send and receive routes to aggregate its hashed portions. also, util module support the capability of operating with the lower-edge (lower adapter) and the upper-edge (virtual adapter) and making read and write with these two bindings of the im driver in kernel level. in addition, it provides a complete packet in a clear buffer in the kernel-mode. flowcharts of the implemented receive functions (ptreceivepacket and ptrecveiveindication) of pij unit are shown in figs. 6.a 6.m. functions preceded by util acronym are belong to pcausa [25] code. after realizing the pij, the next step is to implement the packet filter. omar a. athab al-khwarizmi engineering journal, vol. 5, no. 4, pp 69-98 (2009) 78 fig.6.a. flowchart of pt receivepacket function. fig.6.b. flowchart of im filter_filter receivepacket function. omar a. athab al-khwarizmi engineering journal, vol. 5, no. 4, pp 69-98 (2009) 79 fig.6.c. flowchart of im filter_getfilter action function. fig.6.d. flowchart of util_clone receivepacket function. fig.6.e. flowchart of util_allocatepacket function. omar a. athab al-khwarizmi engineering journal, vol. 5, no. 4, pp 69-98 (2009) 80 fig.6.f. flowchart of im filter_ handle receivepacket function. fig.6.g. flowchart of process pending reads function. omar a. athab al-khwarizmi engineering journal, vol. 5, no. 4, pp 69-98 (2009) 81 fig.6.h. flowchart of mp return packet function. fig.6.i. flowchart of pt receive indication function. fig.6.j. flowchart of im filter_ filter receive indication function. omar a. athab al-khwarizmi engineering journal, vol. 5, no. 4, pp 69-98 (2009) 82 fig.6.k. flowchart of util_make packet from receive indication functions. fig.6.l. flowchart of pt transfer data complete function. omar a. athab al-khwarizmi engineering journal, vol. 5, no. 4, pp 69-98 (2009) 83 fig.6.m. flowchart of im filter_handle receive indication function. 6.2.3. pf unit this section illustrates how to extend the proposed pij so that it has the capability to block the received packets according to a pre-defined list of network ip addresses to be blocked. the basic requirements for ip address blocking driver are:  kernel-firewall: develop a kernel-space software based on the pij driver that blocks packets that are received using an ip addresses list.  application-control: include a companion win32 application that controls and read the list of ip addresses to be blocked. to make the matter more explicit, dropping a packet in the im driver is accomplished by not forwarding it to the upper layer. there is no ndis api to drop a packet. this notion may clarify some of the constraints imposed due to in–kernel programming. generally, the pf provide the capability of a user-mode application to read a list containing the adapter name and the ip addresses to be blocked. the sorted list is passed to the kernel-mode using the pb unit. the list of ip addresses is duplicate in the kernel space and then saved in the filterreserved area of the adapter structure (adapter structure will be explained in section 6.2.4). the starting point of this pf is the pij unit. the base code was reorganized by adding a new module (imfilter.c) that isolates the actual filtering code from the basic packet interception. the key functions provided in the new module are: a. imfilter-setpktfilter function: the imfilteromar a. athab al-khwarizmi engineering journal, vol. 5, no. 4, pp 69-98 (2009) 84 setpktfilter function is responsible to move the information of filter setting from the user application to the context pool of the currently opened adapter. the filter setting information consists of list of destination/source ip address ranges, the action of the filter (block, duplicate (or read), and claim). the adapter must be priory opened by the application before setting the filter parameters. then, the given filter structure that is required to be imposed on the received packet is drawn from the input/output request packet (irp) pointer. completing the irp request is essential to free the resources before returning from the imfiltersetpktfilter. b. imfilter-resetpktfilter function: in the other side, the imfilter-resetpktfilter function resets what the imfilter-setpktfilter has been set. it frees the allocated memory of the recently stored filter structure and nulls the corresponding parameters in the specified open context. finally the imfilter-resetpktfilter will complete the irp request and feedback the suitable status of the processing. c. imfilter-filter receive packet, imfilterhandle receive packet, imfilter-filter receive indication, imfilter-handle receive indication: jobs of theses four are illustrated previously if figs. 6.b, f, i and m, respectively. generally, imfilterfilter receive packet and imfilterfilter receive indication functions are responsible to find the required filter action for the received packet. whereas, imfilter-handle receive packet and imfilter-handle receive indication functions handle the received packet according to the found filter action. 6.2.4. pb unit the devmjfcn.c and wdmsup.c are modules in the kernel side that encapsulates the routines related to the ioctl interface. in user mode side, the modules are realized in c language and then converted to “dll” file such that they export a ready to use apis for the win32 applications of the ar. these apis involve the following: open lower adapter api, open virtual adapter api, open lower adapter by link address api, open virtual adapter by link address api, read on adapter api, write on adapter api, set pkt filter api, reset pkt filter api. in addition to auxiliary apis that are offered to facilitate opening an adapter and querying information, these are: enumerate bindings api, make ndis request api, make private request api. in this paper, the irp-based interface is used to implement the user/driver programming interface. in a consequence, applications can use the basic win32 functions; creat file, devicelo control, read file, write file; and close handle in the user-mode side of the interface. in the main module (section 6.2.1), the driver creates a device object and a win32-visible symbolic link name that can be opened in user-mode using creatfile. also, at main module initialization, the driver was registered irp-based functions that are (eventually) called to implement the kernel-mode end of the interface. the foundation of the device i/o control is accomplished by calling the ndis register device api from the wdm initialize function in the main .c module. using creat file api, the user mode is able to open and close a general device handles on the im driver file space name. a handle of the im file object is an ordinary handle to the device that is not associated with a specific adapter binding. this device handle "or control channel" is used to access global information such as drivers binding list but not beyond that. nevertheless, this handle is not sufficient to make interface with the driver. knowing that, any im driver may be connected to more than one mp nic driver and also more than one overlying pt driver. the connection between the im driver and each one of the underlying mps is represented by a certain adapter structure; we were called (adapter). each adapter structure establishes a driver-specific context area between the im and one of the specified mp drivers. most information and resources used by the pm units such as packet pool handles, buffer pool handles, and locks are kept in this structure. several members of an adapter structure is shown in fig. 7. omar a. athab al-khwarizmi engineering journal, vol. 5, no. 4, pp 69-98 (2009) 85 fig.7. several adapter struct members. 6.2.5. pc unit at this point, a copy of a complete, received, filtered packet has been gained and queued in the pending read packet list in the open-context structure. however, because we use the standard ip header in implementing the ar architecture, we must discriminate the ip which carry an anep header from that which carries non-anep content (i.e. discriminate active from non active packets). we were proposed to use a special value in the protocol field of the ip header to refer to the adp (which contains anep header). in such case, all the required to do by the pc module is to inspect the value of the protocol field in the ip header of the received packet. if it refers to adp, the packet will be passed to the pd unit.the non-adp value of protocol field represents either a traditional data packet (tdp) or a component packet (cp) types, hence the pc re-inject (write) these packets to the virtual adapter of the pij to be lifted to the upper layers for processing. the pc is realized in a discrete function and we call it a clsf function. clsf function takes a pointer to the received packet and its length as input parameters and returns nonzero value if the packet is adp. however, clsf function follows the following steps: examine the type of network layer protocol. according to the protocol type, clsf function can determine which field in the protocol header should be tested to know the packet is an adp or not. according to the suitable header field, if the packet is adp, return non zero value, else return zero value. omar a. athab al-khwarizmi engineering journal, vol. 5, no. 4, pp 69-98 (2009) 86 6.2.6. pd unit after completing the filtering and classification operations, the pc will deliver only the adps to the pd. the pd is a user-mode unit. it is responsible for directing the adps to their appropriate ucs. according to the anep header of the adp, the pd can recognize which uc is required to process the new received packet. as has been stated in section 5.3, the anep header contains a component count (cc) field and a service composition field. these fields tells the pd how many and which uc must be called to process the adp. the order of these ucs is also determined by the anep header. at first, pd delivers an adp from the pc and checks the integrity of the enhanced anep header. then, the pd pushes the adp in a temporary polling cycle to be processed by the appropriate uc. if it is found that one of cids does not recognized, the pd will cancel the packet. jobs of pd unit are implemented as three c++ functions: serv no, serv id, and get serv info. below is a brief description of each one of them: a) serv no function: the serv no function is dedicated to determine how many ucs must be called and executed on the received adp. servno, simply, initialize a pointer to the cc field in the enhanced anep header and return a copy of cc field value. b) serv id function: in other side, serv id function targets to withdraw the cids of the required ucs in a correct order. using the packet array and taking into account the order of the required uc and the type of protocol headers, a pointer to the correct cid value in the service composition field is initialized. this value (cid) will return to the execution environment manager (eem) module (see the next section). actually, the cid is used by eem to search the cached configuration files which, in turn, used to call the associated uc. c) get serv info function: the last support function is the get serv info. it is intended for getting a copy of serv lnfo structure from the configuration file associated with the uc. cid integer will be inserted as input and serv lnfo structure is achieved as output from get serv info function. below is a brief description of the necessary steps followed by get serv info function: define some useful variables. convert the cid integer into an ascii string. search and then open the “.ini” file indicated by cid string. read and copy the file contents into a pre-allocated structure of type serv lnfo. this structure will be exported as output of get serv info function. if the above steps work ok, return a non-zero value, otherwise return a zero. 6.3. active network operation ucs are implemented as dynamic link libraries under windows 2000. since the ar prototype implementations exploit standard link library technique and execute active code within user-space processes, components can be developed and tested based on standard development tools (for example, the visual studio ide compiler and debugger). as dcs can be loaded and executed in the form of binary code, the implementation of the components is conceptually independent from any particular programming language. note that this designed ar doesn't build safety and security upon a specific programming language or certain language constraints (such as strong typing, range checking .. .etc). however, since the apis must be linked to the component at execution time of dll, only programming languages for which the system api is available can be used. at the present time, the system apis of the current ar prototype implementation are only available for c and c++. the software linker between the cd server and the pm in the ar is the eem. the eem is a module designed to integrate the two running software units, namely, the im driver-based and the ftp-based programs. briefly the eem performs the following main jobs: 1. declare two instances of lower and virtual adapters to be used for network access and lowlevel information. 2. define and initialize necessary variables. 3. define two packet arrays (temppack and outpack), one for temporary processing and the other for returning the processed packet. 4. -declare an instance of servinfo structure. it is used to read and store temporarily the contents of the configuration (.ini) file. 5. open the lower and virtual adapters, using apis exported by pb unit (see section 6.2.4). 6. read the received packet(s) and its length from the lower adapter and store it in temppack array. if there is no received packet yet, eem still wait until one is reached to the pendingreadpacketlist buffer. 7. call clsf function (see section 6.2.5) to check if the received packet is an adp or not. clsf function take temppack array and its length as input parameters. if it is non-active packet, eem will write the packet directly in the virtual adapter to be processed traditionally by windows stack. in this case, this packet is either a tdp or a component carrying packet. in the case of tdp, the burden of packet-routing and forwarding is omar a. athab al-khwarizmi engineering journal, vol. 5, no. 4, pp 69-98 (2009) 87 moved to the shoulder of windows protocol layer. whereas, if it is a component carrying packet, windows stack will raise it to the cd server to be dealt with there. in other side, if the packet is an adp then, perform the following steps. 8. declare a general handle to a dll file which is expected to refer to the required uc. 9. call the pd unit. pd will perform the following steps: a) call servno function to get how many ucs are required to process the adp. according to the count of the ucs, steps 9.b up to 12 must be repeated. b) call servid function to get the suitable cid from the composition service field in the enhanced anep header. c) using the cid, the cached configuration files (associated with ucs) are searched to get the correct servlnfo structure. getservinfo function is called to accommodate this job. servlnfo structure contains the name of the uc's dll file whose its cid is given as input to getservinfo function. 10. call the component loader (cl) function. the cl of the ee is responsible for loading ucs into memory, and to initialize and start them. the cl is initiated by the eem. however, steps followed by the designed cl are: a) load the procpacket function from the dll library into memory to be executed. calling loadlibrary api will attempt to locate the dll and then perform such loading. the code file name (i.e. dll name) of the uc is given as input parameter to loadlibrary api. loadlibrary windows api maps the specified executable module (dll) into the address space of the calling process. the returned value will be a specific handle to the required dll library that is loaded in the memory. remembering that a general handle to dll file has been declared in step 8. this handle is assigned now to the handle dedicated to the useful uc returned from loadlibrary. b) given the dedicated dll handle and the name of the exported function (procpacket) as inputs to the getprocaddress api, a pointer to the specified exported dll function (i.e. procpacket function) is returned. procpacket is the template name of the uc function which is required to process the received packet. the function name given to getprocaddress api must be identical to that in the exports statement in the dll's definition (.def) file. 11. to execute procpacket function, temppack array, its length, (a control buffer and its length if required) is passed as input parameters, and then enforce the procpacket function. the actively processed packet is returned in the outpacket array. 12. decrement the count of ucs that has been read in step 9.a. if there are more components must be executed, repeat steps from 9.b up to this step. if component count reaches zero move to step 13. 13. using the developed writeonadapter api, push the processed packet again to the windows stack through writing on the opened virtual adapter to be routed and forwarded conventionally there. 14. as long as there is no manual eem exit instruction, the program continued in step 6. if there is an exit eem instruction, close the lower and virtual adapter instances and exit program. the two support apis (loadlibrary and getprocaddress) are provided by microsoft visual c++6. 7. evaluation and results this section evaluates the designed ar qualitatively and quantitatively. 7.1. packet generator/injector in this paper, an external program is proposed and implemented which creates and then injects data packets into the network stack of the testing machine. we will call this program a packet generator/injector (pgi). the generated packets involve adps and tdps. in each testing course the testing machine which runs the pgi software is connected to the ar (to be tested) or even the es(s). several ready-to-use packet generators/injectors are available as executable software in the internet [29] [30]. all the offered programs use windows socket (winsock) [26] capability to inject user defined packets. the use of winsock involves encapsulating the injected headers (ethernet, ip ... etc) within the transport layer (tcp, for example). this method obliges users to insert virtual headers within the real headers. furthermore, such technique decreases the mtu of the original protocols due to the virtual headers overhead. due to the above reasons, a novel pgi is designed and implemented. it uses only the original protocol headers with full control on filling their fields. also, the designed pgi pushes omar a. athab al-khwarizmi engineering journal, vol. 5, no. 4, pp 69-98 (2009) 88 the generated packets directly to the im driver in the network stack. pgi exploits the implemented pm units. it uses the pij and pb units to inject our created packets directly into the lower adapter. fig. 8 shows a simple block diagram for the designed pgi. a new function in user-space is developed to facilitate creating and injecting data packets by an users in the es. however, it is intended mainly for an developers and not an customers. the function is implemented as stand alone module called pgi.c. fig.8. illustration of pgi units 7.2. evaluation methods in general there are two methods used for the evaluation of system such as that presented within this paper, namely qualitative and quantitative evaluation [2]. since the main contribution of this paper is the architecture for active routers, a qualitative evaluation of the concepts and design of the ar architecture has been regarded as more meaningful. since it has been feasible to implement only a subset of the overall ar architecture, a quantitative evaluation of the entire system (with applications) cannot be provided at this stage. nevertheless, section 7.4 provides a quantitative evaluation of the key units. 7.3. qualitative evaluation issues regarding the design and concepts behind the ar programmability are considered here. in order to evaluate the ar architecture, an example case study is introduced. 7.3.1. case study a) system setup: as illustrated in fig. 9, set up assume existence of an establishment (company, bank, library, campus ... etc) divided into headquarter and other branches distributed around wide area, such that they exchange information through the internet. headquarter may contain multiple networks (lans or/and wans) such that there is a network for each department or section. it is envisioned that ars will form the core elements (access and gateway) of this network. administrator (admn) of the network was decided to operate under tcp/ip suite and running the ars under windows 2000 server. fig.9. hypothetical diagram of computer network of an establishment. omar a. athab al-khwarizmi engineering journal, vol. 5, no. 4, pp 69-98 (2009) 89 b) the challenge: the key challenge of the setting is to "open up" the establishment network and to provide public services (through internet) to remote authorized users (raus). raus may belong to the establishment staff or external customers. it is required to provide sufficient confidentiality for the transferred information from raus to the establishment (headquarter or one of the branches) services. it is decided to provide security by the developed encryption algorithm called "rc5" [31]. c) the solution (network-level encryption): the focus here lies not on the solution itself, as the concepts behind the solution are not specific to ans and therefore can be realized otherwise, but on the fact that the ar provides a generic platform that is sufficiently flexible to resolve this problem. to enable remote rau to send information to a specific section (headquarter or branch) in the establishment, adp are encrypted in the es of rau side. the anep pay load is encrypted using rc5 algorithm [31]. since the transferred information targets one of the multiple sections of the underlying establishment, all gateway routers (which are active) must be prepared to decrypt the arrived adps. the security system can be realized as follows: the software department in the establishment installs rc5 decryption component in the gateway ars which are belong to the establishment. the installed uc (decryption component) has its own cid. rau who wish to benefit from the services introduced by any deterministic section in the establishment must gain the cid and the secret key (user's-specified key). the cid can be gained from publicly shared specifications of the running ars which are distributed by an community. the secret key is distributed securely (manually or through network) by the software department of the establishment to their authorized customers. d) prototype realization: for prototype implementation, the basic setting of case study is minimized into only three computers, namely “a”, “b” and “c”, as shown in fig. 10. computer “b” realizes the gateway active router whereas computer “a” realizes two entities. before any information exchange, computer “a” will represent the pes; actually it is the software department of the establishment which will create and install the uc (the rc5 decryption component). after installing the uc, the function of this computer will be replaced to represent one of the raus who will send encrypted adps to the establishment (computer “c”), through the gateway ar (computer “b”). the three computers have their own ip addresses and also their own nic cards. a unique mac address is assigned to each one. nic cards used in this prototypical setting are of type surecom 10/100m pci adapter and uses fast ethernet protocol. fig. 11 shows a picture for the configured computers of the case study in the laboratory. fig.10. setup of prototype realization of case study. omar a. athab al-khwarizmi engineering journal, vol. 5, no. 4, pp 69-98 (2009) 90 fig.11. configuration of case study in the laboratory. fig.12. flowchart of rc5 encrypting and sending of adps. omar a. athab al-khwarizmi engineering journal, vol. 5, no. 4, pp 69-98 (2009) 91 in this proof-of-concept case study, rau realizes the rc5 encryption algorithm as a single module (rc5.c) using vc++6 environment. a general flowchart of rc5 module realization is shown in fig. 12. as shown in the flowchart, after performing rc5 encryption of adp payload, the rau exploits the previously explained pgi unit to create and then send the packet. the flowchart addresses encrypting and sending of only one adp; however, this routine can be repeated as many as required to proof the concept. software department enforce accurately steps mentioned in section 6.1.3 to implement the two files of the uc of the rc5 decryption algorithm. c++ language is used in programming the code and configuration files. concerning the control buffer in servlnfo structure, it is exploited to store the users' supplied secret key. the flowcharts shown in figs. 13, 14, and 15 are demonstrate the steps of realizing the rc5 decryption component in the pes. in the ar computer (gateway), the preinstalled cd server receive the uc (rc5 decryption function) sent by software department of the establishment. cd server installs the two files (code and configuration) in a pre-defined folder in the ar. however, eem continue running the packet manipulator for searching whether there is a new received packet or not. when the rau begins send the rc5 encrypted adps, eem will perform the required processing (decryption). the word size and number of words are fixed to (32 and 16) respectively, in the implemented decryption component. fig.13. creating the configuration file. omar a. athab al-khwarizmi engineering journal, vol. 5, no. 4, pp 69-98 (2009) 92 fig.14. steps of construction of rc5 decryption component. fig.15. final step in programming the ar. omar a. athab al-khwarizmi engineering journal, vol. 5, no. 4, pp 69-98 (2009) 93 7.3.2. requirement fulfillment requirement 1, namely programmability, is accomplished through the addition of anepbased composition model. in this context, programmability is merely a matter of inserting (or removing) ucs into (from) the packet processing chain on the proposed ar. this is essentially done through loading (or unloading) component's code into the ee (virtual memory) and inserting (or removing) it's cid into (or from) the anep header. requirement 2, demands flexible router functionality. while support for data plane programmability through transparent integration of ucs in the packet processing chain makes the ar a highly extensible platform, the dynamic composition framework proposed by the architecture provides a very flexible means for that. in addition, it is a highly dynamic process that can be efficiently carried out at run time without the need for restarting or even reconfiguring the system. the requirement 3, safety for active code execution within the designed ar is achieved through software fault isolation. requirement 4, secure programmability. simple firewall is achieved by pf unit in pm. in addition, user authentication is accomplished using basic authentication of iis server [24] provided by windows. nevertheless, this is only simple encoded user-name and password authentication. an demands more strong encrypted authentication. more secure system can be considered as a future work for this paper. requirement 5, is to achieve router performance close to the line speed of typical edge networks. later in this section (section 7.4), a performance estimate of our prototype implementation, shows that the ar has not fulfill this requirement completely. from the architectural point of view, there is certainly tradeoff between modularity and performance. since the ar tries to maximize flexibility through the concept of (de-) composition of active services, it trades off performance. for example, adps traversing the ar must be passed to all the components that indicated the interest in the packet. furthermore, the ar architecture has been carefully designed to maximize the performance where possible. because of this, the idea of application-level active-networking has been rejected, and a true network-level approach has been employed instead. for the same reason, ar enables the safe execution of efficient binary code rather than having to rely on code interpretation. requirement 6, which demands easy usability, must be considered from the point of view of the end-users and developers. in the case of our particular implementation of the ar, the development task is greatly facilitated by the design decision to execute active code within the user-space ee, which allows convenient development of user-space code. requirement 7, scalable manageability is not addressed in the work throughout this paper. table 3 lists the relevant requirements and indicates to what extent have been satisfied in the project. table 3, designed ar compliance with relevant an requirements requirement description satisfied? 1 programmability yes 2 flexibility yes 3 safety yes 4 security partially 5 adequate performance partially 6 easy usability partially 7 scalable manageability no 7.4. quantitative evaluation to evaluate the designed ar architecture and hence the performance of the envisaged an, three types of tests were done; control test, an test, and backward compatibility test. three personal computers (we call them “a”, “b”, and “c”) are used to accommodate the experimental setup. one of them (computer “b”) is operate as traditional router (in control test) and as an ar (in the other two tests). the other two computers (“a” and “c”) are used as two different lans. these lan computers are connected directly to the router (computer “b”) using a utp cable. actually, lan computer represents an es in a lan. the nic cards used is of type surecom 10/100mb fast ethernet pci adapter. the hardware architecture of the prototype ar is based on a standard personal computer consisting of single intel pentium 4 omar a. athab al-khwarizmi engineering journal, vol. 5, no. 4, pp 69-98 (2009) 94 microprocessor running at a clock speed of 2ghz, 256 mb of ram and two 100mbps fast ethernet interface. the two interfaces are connected to the two ess. each nic has its own ip and mac addresses such that it belongs to one of the connected lans. the types of the router's interfaces are similar to that of the ess. in the three tests, a data of 360 mb size has been transferred from computer “a” to “c”, through “b”, and all measurements are accomplished at computer “b”. 7.4.1. control test the first test carried out was a control test, which just tested the speed of the network, operating system overhead, and network stack overhead without installing the developed ar software. in control test, computer “b” running windows 2000 server, and it is configured appropriately to operate as a traditional router. packets of tdp type are used in this measurement. the resulting average throughput and cpu loading at computer “b” are shown in table 4. table 4, results of quantitative evaluation tests. test sequence test type throughput (packet/sec) % cpu usage 1 control test 5679.8 30.2 2 an test pm test 2902.6 78.8 5 ucs test 914.9 84.1 10 ucs test 453.1 86.7 15 ucs test 335.8 89.8 3 backward compatibility test 4041.3 75.2 the control test is selected to be a reference gauge, because it represents the actual normal operation of traditional data, router, and protocol. the next two tests, which involve the active enhancement software, will be compared with control test to measure how much degradation and processing cost is paid for active programmability. 7.4.2. active network test in this test, all the implemented software, which has been explained in section 6, is installed in computer b which still running windows 2000 server. the object of this test is to gauge throughput and cpu usage required to achieve the active programmability of the router. an test involves two parts, the first one evaluates the cost of pm and the second measures how many ucs can be processed with keeping reasonable throughput and consuming acceptable cpu time. the developed pgi software is used in computer “a” to construct and send the required adps in each part of an tests. a) pm test: in the first part of an test, the measurements try to quantify the, processing speed and load needed in pm units (namely, pij, pf, pb, pc and pd). the component loader (cl) is suppressed temporarily from the eem to accomplish this target. the resultant throughput and %cpu usage is tabulated in table 4. b) uc test: this test aims to check how many ucs can be used in each service such that the ar is not saturated. however, the evaluation in this paper is directed to evaluate the architecture only and not tied to a specific service or application. hence, applying a specific ucs to implement a certain application or protocol will not fulfils the target of this evaluation, as it is intended to specialized application. five, ten, and fifteen user components are used in three measurement steps. the resultant averages are also shown in table 4. 7.4.3. backward compatibility test in this test, the developed ar software is also installed in computer “b” under windows 2000 server. a stream of tdps (ip packets) is sent from computer “a” toward computer c through the ar. the purpose of this test is to ensure the backward compatibility to the current traditional routers and check the quantity of degradation in throughput and the cost in processing time when ar is used to route tdps rather than traditional router. the results are listed in table 4, too. 7.4.4. discussion the relative high throughput and low % cpu usage in the first experiment, control test, represent the capability of the three computers (namely “a”, “b”, and “c”) during normal omar a. athab al-khwarizmi engineering journal, vol. 5, no. 4, pp 69-98 (2009) 95 networking operation without effects of the driver. it reflects the behavior of in-kernel processing of traditional routing of packets. the first part of an test, namely pm test, gives expected result when it takes approximately double processing time and half throughput with respect to the control test. we can argue that this change is the price that must be paid to transport to the user-level processing of the pm stage (i.e. pb, pc and pd). because of the pij and pf units are operate within the kernel of the router, their effects are negligible. it is agreeable [24] to state that kernel mode processing is faster than the user mode one. concerning the second part of an test (i.e. uc test), the values of measurements refer to the capability of dealing with about 5 user components, acceptably, for each adp. but tests of 10 and 15 ucs show high throughput degradation accompanied by consuming of most processing power. practically, it is also possible to conclude that the system in its current state (experimental) is not extensible when more than 15 ucs are added to the path of adps. this doesn't really affect the validity of the system. it can be solved, for example, by pulling the pc and pd units down to the kernel space which will lead to two times increase in throughput. using multiprocessor router (as in current traditional routers) or upgrading router's hardware by field programmable gate array (fpga) technology may also contribute in solving this shortcoming. the last test "backward compatibility test" is succeeded in proving the compatibility with the current available traditional routers in two aspects. from one side, the ar routes and forwards the tdps (ip packets) correctly without any error or side effects. from the other side, it is not severely affects the standard throughput obtained in control test. the relative little degradation in throughput is due to the overhead of pm units (except pd unit) with paying double processing time. 8. conclusions and future works 8.1. conclusions several conclusions about the development of ar architecture can be drawn from this work:  component-based active router architecture enables network programmability through extensibility of router functionality and services.  active network programmability demands sever safety mechanisms to protect the nodes from malicious or erroneous active code.  reuse of the standard 'process technology' of today's operating systems as safe execution environments for active code has proven to be very practical.  a split implementation across both kernel and user space of the underlying system appears to be a good choice. this approach takes advantage of the high flexibly programming environment in user-mode and sophisticated protection and safety mechanisms of today's oss.  standard user-space implementations for active networks typically suffer largely from the performance hit resulting from the copy operations required to pass the network traffic "up" into user-space and back "down" again. as far as possible, packet processing must be in kernel space. 8.2. future works future work presented in this section focuses on the ongoing development efforts to complete the ar prototype implementation and on using and extending it in order to build and experiment with novel an services: a) the use of poor security scheme is considered one of the shortcomings of this paper. to address this disadvantage, authentication within the ar may be built on public key encryption mechanisms such as rsa or dsa. the user installing a component (or code producer developing a component) encrypts its identity (i.e. user name or company name) with its private key. public key encryption ensures that the encrypted message can only be decrypted with the public key assigned to the user. b) demand-push is the base at which the developed ar depends to install a new uc. to lift the burden from the user's shoulder, it is more pragmatic to distribute a number of component cache servers throughout the an. all that required by the an users is to instruct the suitable uc to be downloaded from the server to the target router. for example, when adp arrives to the ar, the cid will excite a certain program in the ar to download the required uc from the nearest server. this scheme is called a demand-pull mechanism in transferring ucs. c) further decrease in throughput and increase in cpu usage is envisaged with each excess in the number of networks or nodes attached to the designed ar. hence, improvement in an performance still crucial. to decrease the effects of this issue, it is possible to pull the pc and pd down to the kernel level. omar a. athab al-khwarizmi engineering journal, vol. 5, no. 4, pp 69-98 (2009) 96 d) the 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[31] r. l. rivest, "the rc5 encryption algorithm", mit lab. for computer science, usa, 1995. http://dmir.socs.uts.edu.au/projects/%20alan http://www.pcausa.com/ http://www.packetfactory.net/projects/nemesis/windows http://www.packetfactory.net/projects/nemesis/windows http://www.wikistc.org/w/ 98-69، صفحة 4، العذد 5مجلة الخىارسمً الهنذسٍة المجلذ عمز عذاب (200 9) 98 مىجه شبكات لتطبٍقات خاصة باالعتماد على نظام ونذوس ** سفٍان تاٌه فزج*احمذ ستار هادي *عمز علً عذاب جايعت بغذاد / هُذست انخىارسيًال/ انًعهىياث واالتصاالث هُذست قسى* جايعت االَبار/ كهٍت انذاسباث ** الخالصة قهب هذا . تى عًم تًذٍص نهُظى وانتقٍُاث انًزافقت نهشبكت انفعانت انًىجىدة دانٍا. هذا انبذث بذأ بىصف االنٍاث االساسٍت نهذصىل عهى انشبكت انفعانت هذا انًىجه ". ودذاث بُاء انًستخذو" فعال جذٌذ وانذي ًٌكٍ بزيجت انشبكت بًزوَت باالعتًاد عهى (router)انبذث ٌقذو تصًٍى وتُفٍذ نًعًارٌت يىجه وتعشٌش بزوتىكىل windowsفً هذا انًىجه تى استخذاو َظاو انتشغٍم وٌُذوس. انفعال صًى نٍىفز اقصى يزوَت نتًٍُت يهاو وخذياث انشبكت انًستقبهٍت anep . اٌ تعشٌشanep جعم طزٌقت بُاء انخذيت فً هذا انًىجه ٌسًخ بانبزيجت انًزَت يٍ خالل انتجًٍع انشفاف نىدذاث بُاء انًستخذو فً طزٌق كذنك سُقذو وَطبق بزَايج نتشكٍم ودقٍ باكٍتاث انًعهىياث فً طبقاث انشبكت نًاكُت انفذص، سىف َذعى هذا انبزَايج بًىنذ . انبٍاَاث انذاخهت نهًىجت .اخٍزا، َجاح يعًارٌت انعقذة وتُفٍذها االبتذائً تى تقىًٌه باستخذاو بعض انتطبٍقاث انعًهٍت. وداقٍ انباكٍتاث (microsoft word 3446 \343\321\346\311 \336\307\323\343) al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 16, no. 2, june, (2020) p. p. 3446 prediction of cutting force in turning process by using artificial neural network marwa qasim ibraheem department of production engineering and metallurgy/ university of technology/ baghdad/ iraq 70223@uotechnology.edu.iqemail: (received 23 october 2019; accepted 26 april 2020) tps://doi.org/10.22153/kej.2020.04.002ht abstract cutting forces are important factors for determining machine serviceability and product quality. factors such as speed feed, depth of cut and tool noise radius affect on surface roughness and cutting forces in turning operation. the artificial neural network model was used to predict cutting forces with related to inputs including cutting speed (m/min), feed rate (mm/rev), depth of cut (mm) and work piece hardness (map). the outputs of the ann model are the machined cutting force parameters, the neural network showed that all (outputs) of all components of the processing force cutting force ft (n), feed force fa (n) and radial force fr (n) perfect accordance with the experimental data. twenty-five samples of experimental data were used, including nineteen to train the network. moreover six other experimental tests were implemented to test the network. the study concludes that ann was a dependable and precise method for predicting machining parameters in cnc turning operation. keywords: cutting force, ann, turning operation. 1. introduction turning operation is a very rife material removal technique in manufacturing field; researches treat with several sides like: geometric and metallurgical feature of the cutting tool, work piece material effect on the operation and process parameters like (cutting speed, feed rate, and depth of cut). hard turning operation produce high cutting forces and temperatures that effect on cutting parameters , the influence of all these factors give rise to concatenation of physical, chemical and thermo-mechanical phenomena that effect on metal so modeling of cutting forces is necessary [1]. the machining force in turning process is a three-dimensional vector. three components represent it, namely the cutting force ft which is in the direction of cutting axis, the radial force fr in the direction of radial axis and feed force fa in the direction of feed axis the cutting force has the biggest value in the three force components. several researchers learned such components and taking into accounts the effect of cutting variables stachurski, et al. [2] utilized a power polynomial to model the cutting force during turning steel c45. astakhov and xiao [3] applied mathematical models to estimate the cutting forces during machining two materials, aerospace aluminum alloy 2024 and t6aisi bearing steel e52100. hrinath gowd et al. [4] performed experiments involving the effect of cutting forces and surface roughness, which were appreciably influenced by cutting speed, feed and depth of cut, then developed a second order polynomial model in which studied the effect of operating parameters on cutting forces and surface roughness and used rsm for the prediction of mathematical models for estimation of fx, fy, fz and surface roughness. marwa qasim ibraheem al-khwarizmi engineering journal, vol. 16, no. 2, p.p. 3446 (2020) 35 bouacha et al. [5] during machining of aisi 52100 steel with cbn tool show the effect of operating parameters speed, feed and depth of cut on cutting forces and surface roughness by using three level factorial design , the study showed that surface roughness effected by feed rate and cutting speed ,while cutting forces influenced by depth of cut. in this work, an ann process is suggest to predict cutting force components in hard turning feed force fa, radial force fr and cutting force ft. an artificial neural network model is a powerful method to deal with nonlinear functions or to model systems with unknown input–output relations [6-7]. in experimental procedures a lot of money is wasted as well as time. used (ann) as a powerful and accurate tool for machining process modeling to avoid this, where it succeeded in providing an accurate theoretical model and showed accuracy in the modeling of cutting forces quicker than numerous methods that used in complex machining operations such as milling and turning budak et al. [8]. szecsi et al. [9], an analytical model was used which gave the average predictive error (9.5%) on the cutting forces and also provided a neural network for training with an average error rate (3.5%.) where the cutting forces were modeled based feed-forward multilayered neural networks were trained by bp algorithm that inspected the effect of two main factors affecting on error convergence namely education rate η and momentum term α. the neural network is trained on the cases that are reversed during the training process as it is distinguishing by being able to find a base linking outputs to inputs through training operation [10, 11]. mohanned h.al-khafaji[12], built a neural network model in which the cutting parameters were optimize to produce the lowest machining force and the study showed compatibility with experimental data and the calculated correlation coefficients were equal to one. this paper aims to build a neural network model to link the cutting variables, work piece hardness, cutting speed, cutting depth, feed rate, to the machining force during machining of aisi 52100 bearing steel and providing an accurate model for modeling cutting forces faster relying on operating parameters and creating a rule that connects inputs and outputs through training operations. 2. experimental work an empirical data set of cutting forces measured through hard turning of aisi 52100 bearing steel with cbn tool. 2.1 work piece material aisi 52100 steel is great used for a diversity of applications that used in bearings and rotating machinery. like valve bodies, pumps and fittings, etc. schedule (1, 2) display the mechanical properties and chemical composition of aisi 52100 steel respectively. experiments were accomplished dry straight turning operation using lathe type sn 40 and aisi 52100 bearing steel as a work piece material with round bars (40 mm diameter and 250 mm length) with chemical composition in schedule (2) . tool used is cbn 7020, the rake angle γ = 12 °, clearance angle α = 9 °, helix angle λ = 25°, the cutting zone shown in figure (1), figure (2) shows components of machining force. table 1, .aisi 52100 bearing steelechanical properties m tensile yield bulk modulus shear modulus poisson’s ratio thermal conductivity mpa mpa gpa gpa w/m.k 520 415 min 140 80 0.27-0.30 46.6 table 2, .of aisi 52100 bearing steel composition chemicale typical th si mn p s c cr max%～～～～min 0.35～0.15 0.45～0.25 ≤0.015 ≤0.015 1.10～0.95 1.60～1.35 marwa qasim ibraheem al-khwarizmi engineering journal, vol. 16, no. 2, p.p. 3446 (2020) 36 fig. 1. cutting zone. fig. 2. components of machining force [13]. 2.2 artificial neural network after execution the experiments at design matrix, output response measured and recorded be obvious in the schedule (3) cutting speed, feed, cutting depth and work piece hardness are taken as input parameter. table 3, experimental dataset. fa(n) fr(n) ft(n) depth of cut feed speed hrc 15.4 100.3 55.325 0.15 0.05 100 45 1 25.905 85.505 81.205 0.15 0.10 150 50 2 28.153 83.725 105.297 0.15 0.15 200 52 3 29.156 35.945 129.389 0.15 0.20 250 54 4 32.604 122.2 164.9 0.15 0.30 300 56 5 34.313 73.06 72.172 0.20 0.05 150 52 6 35.316 94.28 96.264 0.20 0.10 200 54 7 35.316 85.5 120.4 0.20 0.15 250 56 8 36.319 123.59 136.7 0.20 0.20 300 45 9 47.98 189.84 201.92 0.20 0.30 100 50 10 42.479 81.835 7.231 0.25 0.05 200 56 11 40.245 109.5 113.6 0.25 0.10 250 45 12 39.55 114.175 145.895 0.25 0.15 300 50 13 52.698 154.395 167.247 0.25 0.20 100 52 14 56.146 198.615 216.979 0.25 0.30 150 54 15 48.155 80.51 96.33 0.30 0.05 250 50 16 49.158 101.73 120.422 0.30 0.10 300 52 17 59.861 141.95 158.214 0.30 0.15 100 54 18 60.864 103.2 172.3 0.30 0.20 150 56 19 61.075 194.26 224.29 0.30 0.30 200 45 20 65.431 97.82 126.804 0.40 0.05 300 54 21 76.134 183.04 164.596 0.40 0.10 100 56 22 73.9 146.13 180.94 0.40 0.15 150 45 23 79.7 194.4 206.8 0.40 0.20 200 50 24 79.338 214.6 256.432 0.40 0.30 250 52 25 marwa qasim ibraheem al-khwarizmi engineering journal, vol. 16, no. 2, p.p. 3446 (2020) 37 neural network models are used to predict ft, fr and fa respectively levenberg marquardt algorithm was chosen due to its high accuracy in similar function approximation [14] that used to train the networks in order to improve the generalization of the network, a regularization‟ scheme was used in conjunction with the levenberg-marquardt algorithm. the input/output dataset was divided randomly into two categories: training dataset and test dataset. the automatic bayesian regularization was used for training with levenberg marquardt combined with bayesian regularization. two steps were used to model ann; first for training, whereas second for testing the network. two layer back propagation network was employed as a tool for mapping the complex and highly inter-active process parameters such as cutting speed, feed, depth of cut and work piece hardness. the input data, target data set and testing data used in ann modeling are shown in tables (4&5) respectively table 4, input dataset and target data target data. input dataset fa(n) fr(n) ft(n) depth of cut feed speed hrc exp no. 25.9 85.5 81.2 0.15 0.10 150 50 2 28.2 89.7 105.3 0.15 0.15 200 52 3 29.2 95.9 129.4 0.15 0.20 250 54 4 34.3 73.1 72. 2 0.20 0.05 150 52 6 35.3 94.3 96.3 0.20 0.10 200 54 7 36.3 123.6 136.7 0.20 0.20 300 45 9 47.9 189.8 161.9 0.20 0.30 100 50 10 42.5 81.8 87.2 0.25 0.05 200 56 11 39.6 114.2 145. 9 0.25 0.15 300 50 13 52.7 154.4 167.2 0.25 0.20 100 52 14 56.1 99.6 176.9 0.25 0.30 150 54 15 48.2 80.5 96.3 0.30 0.05 250 50 16 49.2 98.7 130.4 0.30 0.10 300 52 17 59.9 141.9 158.2 0.30 0.15 100 54 18 63.1 190.3 184.3 0.30 0.30 200 45 20 65.4 97.8 126.8 0.40 0.05 300 54 21 76.1 146.0 164.6 0.40 0.10 100 56 22 77.9 184.1 180.9 0.40 0.15 150 45 23 82.3 198.6 189.4 0.40 0.30 250 52 25 table 5, testing data exp no hrc feed speed depth of cut 1 45 0.05 100 0.15 5 56 0.30 300 0.15 8 56 0.15 250 0.20 12 45 0.10 250 0.25 19 56 0.20 150 0.30 24 50 0.20 200 0.40 3. results and discussion 3.1 analysis of variance the experimental results were from table (3) analyzed with an analysis of variance (anova), which they are used to determine the factors that most influence the performance characteristics (cutting forces) are shown in table (6, 7, and 8) respectively. the overall significant of mathematical model can be seen in table (6,7,8) respectively ,the greatest value of f ratio among the variables was (18.88) for feed accordingly the mostly effected variable on fr with p-value (0.000) and rsq(adj)= 85.15% as see in schedule(6). marwa qasim ibraheem al-khwarizmi engineering journal, vol. 16, no. 2, p.p. 3446 (2020) 38 from schedule (7) the most influence variable is depth of cut with f ratio (333.46), pvalue(0.000)and r-sq(adj)= 98.40% for fa . from schedule ( 8 )the most influence variable on ft value was fee with f ratio (861.72), p-value (0.000) and r-sq(adj)= 99.51% . figure (3,4,5), illustrate the residual plot for fr,fa,ft respectively . table 6, analysis of variance for fr source df adj-ss adj-ms f-value p-value speed 4 7163 1790.8 5.24 0.023 feed 4 25800 6449.9 18.88 0.000 depth 4 17599 4399.7 12.88 0.001 hrc 4 1900 475.0 1.39 0.320 error 8 2733 341.6 total 24 55194 r-sq= 95.05% r-sq(adj)= 85.15% r-sq(pred)= 71.65% fig. 3. residual plot for fr table 7, analysis of variance for fa source df adj-ss adj-ms f-value p-value speed 4 131.39 32.85 6.42 0.013 feed 4 616.43 154.11 30.14 0.000 depth 4 6820.81 1705.20 333.46 0.000 hrc 4 53.98 13.49 2.64 0.113 error 8 40.91 5.11 total 24 7663.52 r-sq= 99.47% r-sq(adj)= 98.40% r-sq(pred)= 94.79% 20100-10-20 99 90 50 10 1 rrrreeeessss iiiidddduuuuaaaallll pp pp ee ee rr rr cc cc ee ee nn nn tt tt 20015010050 20 10 0 -10 -20 ffff iiiitttt tttteeeedddd vvvvaaaalllluuuueeee rr rr ee ee ss ss ii ii dd dd uu uu aa aa ll ll 20100-10-20 6.0 4.5 3.0 1.5 0.0 rrrreeeessss iiiidddduuuuaaaallll ff ff rr rr ee ee qq qq uu uu ee ee nn nn cc cc yy yy 24222018161412108642 20 10 0 -10 -20 oooo bbbbssss eeeerrrr vvvv aaaatttt iiiioooonnnn oooo rrrr ddddeeeerrrr rr rr ee ee ss ss ii ii dd dd uu uu aa aa ll ll nnnnoooorrrrmmmmaaaallll pppprrrroooobbbbaaaabbbbiiii llll iiii tttt yyyy ppppllllooootttt vvvv eeeerrrrssss uuuussss ffffiiii tttt ssss hhhhiiiissss tttt ooooggggrrrraaaammmm vvvveeeerrrrssss uuuussss oooorrrrddddeeeerrrr rrrreeeessssiiiidddduuuuaaaallll pppplllloooottttssss ffffoooorrrr ffffrrrr((((nnnn)))) marwa qasim ibraheem al-khwarizmi engineering journal, vol. 16, no. 2, p.p. 3446 (2020) 39 fig. 4. residual plot for fa. table 8, analysis of variance for ft source df adj-ss adj-ms f-value p-value speed 4 282.3 70.6 5.34 0.022 feed 4 45527.4 11381.9 861.72 0.000 depth 4 18325.3 4581.3 346.85 0.000 hrc 4 80.7 20.2 1.53 0.282 error 8 105.7 13.2 total 24 64321.4 r-sq=99.84% r-sq(adj)= 99.51% r-sq(pred)= 98.40% fig. . 5. residual plot for ft. 20-2-4 99 90 50 10 1 rrrreeeessss iiiidddduuuuaaaallll pp pp ee ee rr rr cc cc ee ee nn nn tt tt 80604020 2 0 -2 ffff iiii tttt tttt eeeedddd vvvvaaaalllluuuueeee rr rr ee ee ss ss ii ii dd dd uu uu aa aa ll ll 10-1-2-3 4 3 2 1 0 rrrreeeessss iiiidddduuuuaaaallll ff ff rr rr ee ee qq qq uu uu ee ee nn nn cc cc yy yy 24222018161412108642 2 0 -2 oooo bbbbssss eeeerrrr vvvv aaaatttt iiiioooonnnn oooo rrrr ddddeeeerrrr rr rr ee ee ss ss ii ii dd dd uu uu aa aa ll ll nnnnoooorrrrmmmmaaaallll pppprrrroooobbbbaaaabbbbiiii llll iiii tttt yyyy pppp llllooootttt vvvveeeerrrrssss uuuussss ffffiiii tttt ssss hhhhiiii ssss tttt ooooggggrrrraaaammmm vvvveeeerrrrssss uuuussss oooorrrrddddeeeerrrr rrrreeeessss iiiidddduuuuaaaallll pppplllloooottttssss ffffoooorrrr ffffaaaa((((nnnn)))) 5.02.50.0-2.5-5.0 99 90 50 10 1 rrrreeeessss iiiidddduuuuaaaallll pp pp ee ee rr rr cc cc ee ee nn nn tt tt 25020015010050 5.0 2.5 0.0 -2.5 -5.0 ffff iiiitttt tttteeeedddd vvvvaaaalllluuuueeee rr rr ee ee ss ss ii ii dd dd uu uu aa aa ll ll 420-2-4 8 6 4 2 0 rrrreeeessss iiiidddduuuuaaaallll ff ff rr rr ee ee qq qq uu uu ee ee nn nn cc cc yy yy 24222018161412108642 5.0 2.5 0.0 -2.5 -5.0 oooo bbbbssss eeeerrrr vvvv aaaatttt iiiioooonnnn oooo rrrr ddddeeeerrrr rr rr ee ee ss ss ii ii dd dd uu uu aa aa ll ll nnnnoooorrrrmmmmaaaallll pppprrrroooobbbbaaaabbbbiiii llll iiii tttt yyyy pppp llllooootttt vvvveeeerrrrssss uuuussss ffffiiii tttt ssss hhhhiiii ssss ttttooooggggrrrraaaammmm vvvveeeerrrrssss uuuussss oooorrrrddddeeeerrrr rrrreeeessssiiiidddduuuuaaaallll pppplllloooottttssss ffffoooorrrr fffftttt((((nnnn)))) marwa qasim ibraheem al-khwarizmi engineering journal, vol. 16, no. 2, p.p. 3446 (2020) 40 while, the mathematical model for fr,fa,ft are developed as shown in equations (1,2,3) to represent the relationship between the input parameters speed(s), feed(f),depth of cut(d) ,work piece hardness (hrc) and the response fr,fa,ft fr(n)=124.40+ 29.50 s-100 3.10 s-150 + 5.30 s-20019.19 s-25012.50 s-30037.70 f0.059.59 f_0.1010.11 f-0.152.10 f-0.20 + 59.50 f-0.3038.87 d-0.1511.15 d0.20+ 7.30 d-0.250.07 d-0.30+ 42.79 d0.40+ 10.35 hrc-45 + 8.48 hrc-50 + 1.10 hrc-52 10.68 hrc-54 9.25 hrc-56 ...(1) fa(n)=48.208+ 2.207 s-100+ 2.018 s-150 + 1.137 s-200 1.766 s-2503.595 s-300 7.052 f-0.052.856 f-0.100.852 f0.15+ 3.540 f-0.20+ 7.221 f-0.3021.964 d0.1510.359 d-0.201.984 d-0.25+ 7.615 d0.30+ 26.693 d-0.402.820 hrc45+ 0.050 hrc-50+ 0.524 hrc-52 + 0.974 hrc-54 + 1.272 hrc-56 ...(2) ft(n)=144.066+ 5.39 s-100 + 0.65 s-150 0.09 s-2000.84 s-2505.12 s-30056.49 f0.0528.85 f-0.101.92 f-0.15+ 18.42 f-0.20 + 68.84 f-0.3036.84 d-0.1518.57 d0.20+ 2.12 d-0.25+ 10.25 d-0.30+ 43.05 d-0.401.90 hrc-4+ 2.36 hrc-50+ 0.25 hrc-52 + 1.46 hrc-54 2.18 hrc-56 ...(3) 3.2 development of ann modelling neural network model consist of four input neurons and three output corresponding to cutting speed (s), feed–rate (f),work piece hardness (hrc),depth (d) and (ft,fr,fa) respectively by used hebbian learning rule . the number of the hidden layer and the number of neurons equal to (2) and (4) respectively. number of input parameters is equal to 4; figure (6) shows the schematic view of the neural network used. fig.. 6. the schematic view of the neural network used. network model network kind: feed forward back propagation training: levenberg maquardtl algorithm number of layers: 2 output layer: 3 number of neurons: 4 performance: mean square error transfer function for hidden layer: tran sigmoid transfer function for output: pure linear adaption of learning rate: learngdm marwa qasim ibraheem al-khwarizmi engineering journal, vol. 16, no. 2, p.p. 3446 (2020) 41 fig. .7. the graphical representation of the proposed network. the experimental database is utilized to construct the neural network. about 24% of data are utilized for model testing, whereas 76% of data are utilized for model training. figure (7) show the graphical representation of the proposed network while figure (8) shows the best validation performance was (727.3687) at epoch 6. fig. 8. mean square error-number of epochs error % = (measuredpredicted)/ measured *100%)| ... (4) mse = ∑ (measuredpredicted) ^2/ number of experiments … (5) table (9) shows the measured and predicted cutting forces obtained in testing, as well as the mean square error (mse) values. it can be seen from this table that the average prediction error� � � found (4.57%, 4.925%, and 4.62%) the accuracy was (95.43%, 95.075%, and 95.38%) and mse (2.345, 40.2, and 85.37%) relative to fa, fr, ft respectively. 50 100 150 200 250 50 100 150 200 250 target o u tp u t ~ = 1 *t a rg e t + 0 .0 1 training: r=1 data fit y = t 50 100 150 200 250 50 100 150 200 250 target o u tp u t ~ = 1 .1 *t a rg e t + 5 .5 validation: r=0.93428 data fit y = t 50 100 150 200 250 50 100 150 200 250 target o u tp u t ~ = 0 .5 7 *t a rg e t + 3 2 test: r=0.75162 data fit y = t 50 100 150 200 250 50 100 150 200 250 target o u tp u t ~ = 0 .9 6 *t a rg e t + 4 .5 all: r=0.9543 data fit y = t 0 1 2 3 4 5 6 7 8 9 10 -25 10 -20 10 -15 10 -10 10 -5 10 0 10 5 best validation performance is 727.3687 at epoch 6 m e a n s q u a re d e rr o r ( m s e ) 9 epochs train validation test best marwa qasim ibraheem al-khwarizmi engineering journal, vol. 16, no. 2, p.p. 3446 (2020) 42 table 9. results testing dataset ft(n) fr(n) fa(n) input testing data error (%) predic ted measu red error (%) predic ted measu red error (%) predic ted measu red hr c feed speed depth of cut exp no 1.08 54.7 55.3 4.79 105.1 100.3 13.6 4 17.5 15.4 45 0.05 100 0.15 1 8.98 179.7 164.9 8.67 111.6 122.2 4.60 31.1 32.6 56 0.30 300 0.15 5 5.40 126.9 120.4 11.22 75.9 85.5 0.57 35.1 35.3 56 0.15 250 0.20 8 3.17 117.2 113.6 3.47 113.3 109.5 5.22 42.3 40.2 45 0.10 250 0.25 12 1.80 169.2 172.3 0.78 102.4 103.2 1.64 61.9 60.9 56 0.20 150 0.30 19 7.30 221.9 206.8 0.62 195.6 194.4 1.76 81.1 79.7 50 0.20 200 0.40 24 �(%)=4.62, mse=85.37, accuracy (%)=95.38 �(%)=4.925, mse=40.2, accuracy (%)=95.075 �(%)=4.57, mse=2.345, accuracy (%)=95.43 the expected and empirical values of fa, fr and ft as shown in the testing results in table (9), which was represented in figures(9, 10, & 11 ) respectively show that the network gave good interaction with the test data . fig. 9. experimental & predicted fa values for testing data set. fig. 10. experimental & predicted fr values for testing data set. fig. 11. experimental & predicted ft values for testing data set. marwa qasim ibraheem al-khwarizmi engineering journal, vol. 16, no. 2, p.p. 3446 (2020) 43 fig. 12. experimental testing cutting force components as a function of: acutting speed (f=0.1; d=0.15; hrc=45) bdepth of cut (f=0.1; s= 150; hrc=45) cfeed (s= 150; d= 0.15; hrc= 45) as mentioned previously, there are many parameters of the process that have a significant impact on the experimental cutting forces, figure (12) shows the difference of cutting forces with the cutting speed, feed and depth of cut, which can be observed through figure (12 a, b , c), so it is natural to prefer numerical techniques such as artificial neural networks or multiple regression or genetic algorithm to describe the efficiency of a complex process. table 10, comparison between ann vs. experimental values for cutting forces in training from table (10) the average prediction error� � � values are found for fa, fr and ft predictions. it was 0.526%, 0.476%, and 0.257%, respectively figure (13) shows the final graphical comparison between experimental and predicted cutting forces in training. as shown in table 10, a good and comprehensive match was found between numerical and experimental results , however a variation in results was observed, as the mape was from 0.16 to 3.68% for the fa and from 0.61 to 8.38% for fr while for ft was from 0.21 to 4.15% essentially, the ann model appears to have proven to be effective, however its accuracy can be further no depth of cut feed speed hrc annf a exp fa error( %) ann fr exp fr error( %) ann ft exp ft error(%) 1 0.15 0.10 150 50 25.2 25.9 2.70 85.5 85.5 0.00 81.5 81.2 0.36 2 0.15 0.15 200 52 28 28.2 0.70 89.7 89.7 0.00 105.3 105.3 0.00 3 0.15 0.20 250 54 29.2 29.2 0.00 95.9 95.9 0.00 129.4 129.4 0.00 4 0.20 0.05 150 52 34.3 34.3 0.00 73.1 73.1 0.00 72.2 72.2 0.00 5 0.20 0.10 200 54 35.3 35.3 0.00 86.3 94.2 8.38 100.3 96.3 4.15 6 0.20 0.20 300 45 36.3 36.3 0.00 123.6 123.6 0.00 136.6 136.6 0.00 7 0.20 0.30 100 50 47.9 47.9 0.00 189.8 189.8 0.00 161.9 161.9 0.00 8 0.25 0.05 200 56 42.7 42.5 0.81 82.3 81.8 0.61 87.3 87.2 0.11 9 0.25 0.15 300 50 39.6 39.6 0.00 114.2 114.2 0.00 145.9 145.9 0.00 10 0.25 0.20 100 52 52.7 52.7 0.00 154.4 154.4 0.00 167.2 167.2 0.00 11 0.25 0.30 150 54 56.1 56.1 0.00 99.6 99.6 0.00 176.9 176.9 0.00 12 0.30 0.05 250 50 48.2 48.2 0.00 80.5 80.5 0.00 96.1 96.3 0.21 13 0.30 0.10 300 52 49.2 49.2 0.00 98.7 98.7 0.00 130.4 130.4 0.00 14 0.30 0.15 100 54 59.8 59.9 0.16 141.9 141.9 0.00 158.1 158.2 0.06 15 0.30 0.30 200 45 63.1 63.1 0.00 190.3 190.3 0.00 184.3 184.3 0.00 16 0.40 0.05 300 54 66.2 65.4 1.22 97.8 97.8 0.00 126.8 126.8 0.00 17 0.40 0.10 100 56 75.9 76.1 0.26 146.1 146 0.06 164.6 164.6 0.00 18 0.40 0.15 150 45 75.1 77.9 3.68 184.1 184.1 0.00 180.9 180.9 0.00 19 0.40 0.30 250 52 82.7 82.3 0.48 198.6 198.6 0.00 189.4 189.4 0.00 marwa qasim ibraheem al-khwarizmi engineering journal, vol. 16, no. 2, p.p. 3446 (2020) 44 enhanced by improving some ann parameters, such as learning rate and momentum fig. 13. comparison between experimental vs. ann for training 4. conclusions a model for predicting values of fa, fr and ft were developed by artificial neural networks techniques, full factorial design used to implement the empirical design.(ann) program in matlab used to find the relation between the input process parameters and the output variables. from the anova analysis, found that the most influencing factor on the fr values was the feed with f-ratio (18.88), followed by the depth of the cut with f-ratio (12.88) while the most influence variable on fa was depth of cut with fratio (333.46) and for ft was feed with f-ratio (861.72). the better model were chosen dependent on the best performance error for different network components then plotted the graphs between the measured and predicted values in the ann results, models have been estimated by means of the percentage deviation between the predict values and the actual values. from training results the average prediction error � � �found (0.526%, 0.476%, and 0.257%) the accuracy was (99.474%, 99.524%, 99.743%) and mse (0.487%, 3.298%, 0.850%) relative to fa, fr, ft respectively. it is clear that the ann predicted results shows perfect correspond with the empirical results, ann demonstrate its qualification in optimizing the turning process parameters. the sophisticated ann model can be further joined with optimization algorithms like ga to improve the end milling parameters. 5. references [1] dimla, d. e., application of perceptron neural networks to tool state classification in metalturning operation. elsevier, engineering applications of artificial intelligence, 12, 471–477, 1999. [2] w. stachurski, s. midera and b. kruszy, "determination of mathematical formulae for the cutting force fc during the turning of c45 steel," mechanics and mechanical engineering, vol. 16, no. 2, pp. 73-79, 2012. [3] v. p. astakhov and x. xiao, "a methodology for practical cutting force evaluation based on the energy spent in the cutting system," machining science and technology, vol. 12, no. 3, pp. 325-347, 2008. [4] gowd g.h., reddy m.g. and sreenivasulu b. empirical modelling of hard turning process of inconel using response surface methodology. international journal of emerging technology and advanced engineering, 2012; issn 22502459. [5] bouacha, k., yallese, m . a . , m abrouki, t. and rigal, j.f. statistical analysis of surface roughness and cutting forces using response surface methodology in hard turning of aisi 52100 bearing steel with cbn tool, international journal of refractory metals & hard materials, vol. 28, pp. 349-361. (2010), [6] murata, n.; yoshizawa, s.; amari, s. network information criterion-determining the number of hidden units for an artificial neural network model. ieee trans. neural netw. 5, 865– 8721994, [crossref] [pubmed] [7] jain, s.p.; ravindra, h.v.; ugrasen, g.; prakash, g.v.n.; rammohan, y.s. study of surface roughness and ae signals while machining titanium grade-2 material using ann in wedm. in materials today: proceedings; elsevier: amsterdam, the netherlands, pp. 9557–9560, 2017; [8] budak, e., ozlu, e., development of a thermomechanical cutting process model for machining process simulations, cirp annalsmanufacturing technology, 57, 97-100, 2008. [9] szecsi, t., cutting force modeling using artificial neural networks, elsevier, journal of materials processing technology, 92-93, 344 349, 1999. [10] klancnik, s., balic, j., cus, f.: intelligent prediction of milling strategy using neural networks. control cybern, vol. 39, 1, (2010), 9-22. marwa qasim ibraheem al-khwarizmi engineering journal, vol. 16, no. 2, p.p. 3446 (2020) 45 [11] cukor, g., jurkovic, z.: optimization of turning using evolutionary algorithms. technical gazette, vol. 30, 2 (2010), 1-10. [12] mohanned h. al-khafaji ; neural network modeling of cutting force and chip thickness ratio for turning aluminum alloy 7075-t6 h. al-khwarizmi engineering journal, vol. 14, no. 1, p.p. 67 76 (2018) [13] http://images.app.goo.gl/lnfhrmxh3zrjxy8 c8 [14] malinov s, sha w, modeling the correlation between processing parameters and properties in titanium alloys using artificaial neural networks, comput. mater. sci. 21 (2001) page 375 – 394. . �وى �� ا��اھ�� �� 2ا���د، ����16 ا���ارز � ا������� ا����� ،2020( 3446( 46 ا�(�$. �-�ى ا�-", +� !���� ا���اط� � �(��ام ا�'$&� ا��%$�� ا# "� !�� �وى �� ا��اھ�� ا3h2i5> اabc<def5f?g95 ھ?<=> ا;:29ج وا2345دن/ 70223@uotechnology.edu.iq :k:وl9g5mا >nlo5ا �/ �ا� <pqrو stu5ا v4wو <nxy95وا <wlb5ا z[h zhاfw l\]^ . _9?45دة اfeو <?da245ا zdyb^ <d:2ghا >n>c95 <4d45ا zhاf35ا eh stu5ى اfc >3^ ذات اrداة fbh qiw:> اptb5 وfcى اdi4w ko stu5> اlm5اط> .^a ا=m9<ام :f4ذج اgob5> اdoj35> اfup ]o?9i5 <dw2?trmى اsh stu5 اqh>45ت ko 24p <ij5 ذwl= u5> اstu5 و3h<ل اnxy95> وv4w اstu5 و3tc <pqr> اfc .z435ى اstu5 ا2elmh z[4^ s:2a <d5rت اgob5> اdoj35> ا <up2t9h <dw23b5ة اfu5وا <nxy95ة اfcو stu5ة اfc <i52345ى اfc 2ت:fgh sd4i5 (2تelm45ا) sd4e ان <doj35ا <gob5ت اldاظ ، <dw2?trm2 اh24^ =2:2do5 <9ت اa^ .<donli95 ا=m9<ام b4h> وlbwون eh <?dw ا2:2do5ت اko 24p ، <donli95 ذs:2a lbw <3b^ u5 95<رxn اqw ،<gob5وة qiw ذsh u5 ا 2o9hmر اgob5> . وsjm5 ا5<را=> اq5 ان اgob5> اdoj35> اdw2?trm> طcf\fh <unl> ود24i34p ]o?9i5 <udcت اdi4w ko stu5> اlm5اط> microsoft word 1-12???? ???? this is an open access article under the cc by license :   al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 17, no. 3, sptember, (2021) p. p. 1-12 optimization of cutting parameters for milling process of (4032) al-alloy using taguchi-based grey relational analysis sami abbas hammood department of production engineering and metallurgy/ university of technology/ baghdad/ iraq sami.a.hammood@uotechnology.edu.iq: email )received 25 april 2021; revised 6 june 2021; accepted 27 june 2021 ( 1.0006https://doi.org/10.22153/kej.2021. abstract the objective of this work is to study the influence of end milling cutting process parameters, tool material and geometry on multi-response outputs for 4032 al-alloy. this can be done by proposing an approach that combines taguchi method with grey relational analysis. three cutting parameters have been selected (spindle speed, feed rate and cut depth) with three levels for each parameter. three tools with different materials and geometry have been also used to design the experimental tests and runs based on matrix l9. the end milling process with several output characteristics is solved using a grey relational analysis. the results of analysis of variance (anova) showed that the major influencing parameters on multi-objective response were spindle speed and cutting tool with contribution percentage (52.75%, 24%), respectively. in addition, the optimum combination of end milling process parameters was then validated by performing confirmation tests to determine the improvement in multi-response outputs. the confirmation tests obtained a minimum (surface roughness and micro-hardness) and maximum metal removal rate with grey relational grade of 0.784 and improvement percentage of 2.3%. keywords: al-alloy 4032, end milling process, grey relational analysis, multi-objective optimization, taguchi method. 1. introduction there is an increase in the demand to produce complex 3d shapes with sharp edges, better surface quality (low surface roughness and hardness), maximum productivity and low-cost machining such as production cars, die sinking and many engineering industries. this has led to increase the demand to use the traditional cutting operations such as milling cutting operation rather than using the non-traditional operations. the milling process is the one important part of the conventional machining process, which can machine fine, rough, unsymmetrical, slot and curved surfaces by movement of the work part against a rotating multi-flute cutting tool. the machines used in the milling process can be classified as either vertical or horizontal machines [2,6-8,11,16]. there are three main parameters (spindle speed, feed rate, and cut depth) found in any type of milling machine, as well as other parameters that influence the milling process such as (cutting tool and workpiece material), which can give the designer and worker (operator) flexibility to change, select, and control between them to achieve high quality, maximum productivity, and practical properties of the milling process [2-8]. the end milling process is an important type of milling operation, which is used to machine simple and complex surfaces with faster removal rate and high quality of the surface. the cutting tool used in the end milling process is called an end mill cutter with a diameter less than the width of the work part and has number of  sami abbas hammood al-khwarizmi engineering journal, vol. 17, no. 3, p.p. 112 (2021)    2   flutes (teeth) starting from 2 flutes. the vertical milling machine is used in the end milling process because the cutter rotates vertically against the workpiece. in the end milling process, the tool path required to machining and finish product is performed in one pass or in multi-passes depending on the width of the workpiece, diameter of the cutter and depth of cut [6-8,11]. in recent years, the computer numerical control (cnc) system has been used to convert a manual milling machine into a full automation machine (cnc milling machine), which can control the movement of end mill cutter using coded (g and m) instructions processed by a computer and the capability to perform repeat tasks with high accuracy [2-8]. the used cnc offers additional flexibility, computational capability, provides high enhancement in productivity and quality of the machining surface compared with using a conventional nc machine. in recent years, al-alloys have developed as the superior alloys used for different applications such as automobile, aerospace industries and die parts manufacturers because of their desirable characteristics such as high resistance to corrosion and wear, great electrical and thermal conductivity, high strength, less weight. [4,6,8,12,13]. the measurement of surface roughness is a significant performance quality of the machined surface in machining processes, which affects mechanical properties like fatigue, corrosion resistance, creepage, and other useful features like friction, wear, lubrication, electrical conductivity, and so on [3,7-9,13-16]. the rate of metal removal is important performance productivity in machining processes. to increase the productivity which leads to performed machining processes with less time and cost. the rate of metal removal can be estimated depended on cutting parameters with cutter flutes or measurement by difference weight to cutting time [1,6,11]. micro-hardness is an important element in determining the surface integrity during the machining process. micro-hardness calculation is used to assess the machined surface's functional activity and to calculate the work hardening effect caused by machining operations. the difference between machining impacted areas and the bulk metal is determined using micro-hardness calculation [3,9,14,15]. however, single objective methods such as taguchi analysis have a minimal value in deciding the optimum cutting parameters as many distinct and incompatible objectives must be tailored at the same time. as a result, cutting parameter optimization has reported multiobjective methods that consider many distinct and conflicting objectives [1-16]. grey relational analysis is an important tool for optimizing the complex inter-relationships between multiple output characteristics. in addition, the grey relational grade is obtained by grey relational analysis, which can be determine the various output characteristics. as an outcome, optimization of the complex multiple output characteristics can be translated into the optimization of a single grey relational grade. for combining grey relational method and the taguchi analysis, the grey-taguchi method was developed. the grey-taguchi approach has been used to effectively optimize the various output characteristics of complex manufacturing operations [1-6,10-16]. many attempted optimization studies have investigated the effect of cutting parameters of the end milling process by using grey relational analysis based on the taguchi method for multiresponse optimization for al-alloys. in this study, the effect of cutting parameters (spindle speed, feed and depth) is investigated combining with tool material and geometry on the multi-performance of the end milling process (low surface roughness and micro-hardness, high metal removal rate), through analyzing the measurement of the outputs by used grey relational analysis based on taguchi method for alalloys. 2. experimental procedures 2.1 workpiece material and dimension the raw material used in the experiments was al-alloy 4032 with chemical compositions and mechanical properties shown in table 1,2. it was provided in the form of a block with dimensions (60 mm x 90 mm x 70 mm). the workpiece material was cut into nine blocks with dimensions of (60×42×12 mm) from the origin block to perform experiments as shown in figure (1). this alloy is used in applications such as (forgings for the automobile industry, engine pistons, valves and hydraulic parts) and has superior wear resistance and low coefficient of thermal expansion. as a result, it is advised that high-temperature materials are needed to be used.  sami abbas hammood al-khwarizmi engineering journal, vol. 17, no. 3, p.p. 112 (2021)    3   fig. 1. the workpiece with its dimensions. table 1, chemical composition for al-alloy (4032) element al si mg cu ni cr zn fe concentration (wt %) 84.2 11.7 1.1 0.7 0.9 0.1 0.1 1.2 table 2, mechanical properties for al-alloy (4032) tensile strength young's modulus vickers hardness 368 mpa 78 gpa 137 hv 2-2 cutting tool three cutting tools were used in the experiments as shown in figure (2) and materials, dimensions are presented in the table 3. fig. 2. tools (end mill cutters) used in experimental work. table 3, materials and dimensions of cutting tools used in the experiments. no. tool type mill diameter (mm) shank diameter (mm) no. of flutes (teeth) cut length (mm) total length (mm) helix angle 1 h.s.s 14 16 4 40 84 30° 2 h.s.s coated with tin 14 12 4 26 80 30° 3 carbide-titanium 14 14 5 26 81 45° 2.3 cnc vertical milling machine a computerized numerical control (cnc) vertical milling machine shown in figure 3, was used to machining workpieces of al-alloys (4032), using the tools mentioned above at specified cutting parameters (spindle speed, feed rate and cut depth). description to the specifications of the cnc machine is given in the tables 4 and 5.  sami abbas hammood al-khwarizmi engineering journal, vol. 17, no. 3, p.p. 112 (2021)    4   fig. 3. cnc vertical milling machine used in the experimental work. table 4, description of the specifications of the cnc machine (knuth rapimill 700) specifications data table dimensions 300 x 770 mm t-slots 16 x 3 x 80 mm table load 120 kg movements x-axis 400 mm y-axis 300 mm z-axis 250 mm distance from spindle nose to table surface 100 350 mm distance from spindle center to bed 350 mm feed rapid speed of the axes x, y, z 30000 rpm cutting feed x, y, z 4000 rpm spindle spindle speed 10000 rpm motor the required operating air pressure 6 kg / cm2 dimensions l*w*h 1570 x 2135 x 2175 mm machine weight 2200 kg motor-spindle cnc 3.7 kw / 4.7 kw x, y, z motor 0,7 kw motor spindle 5.5 kw / 7.5 kw x, y, z servo 1.2 kw 2.4 experimental design and selection of cutting parameters to investigate the influences of cutting parameters, tool material and geometry on the process performance (surface roughness, microhardness, metal removal rate), grey relational analysis based on the taguchi method have been used. for this study, three cutting tools and three cutting parameters (spindle speed, feed rate, and cut depth) were chosen at three levels. running of the experimental tests depended on a matrix l9 (4 factors * 3 levels) of taguchi analysis. in order to clarify the reasons for improvements in the results response, changes in the cutting parameters have been made. nine tests have been performed and the work procedures have been presented in the flow chart as shown in figure 4. as seen in the table (5), one parameter changed at three different levels in each test, while the other parameters remained unchanged [2,4-8,11,15-18]. fig. 4. flow chart of work procedures.  sami abbas hammood al-khwarizmi engineering journal, vol. 17, no. 3, p.p. 112 (2021)    5   table 5, cutting tools and machine cutting parameters. test no. levels of control factors type of tool (a) spindle speed (b) r.p.m feed rate(c) mm/tooth depth of cut (d) mm 1 h.s.s 2000 0.03 0.5 2 3000 0.06 1 3 4000 0.1 1.5 4 h.s.s coated with tin 2000 0.06 1.5 5 3000 0.1 0.5 6 4000 0.03 1 7 carbide-titanium 2000 0.1 1 8 3000 0.03 1.5 9 4000 0.06 0.5 2.5 cutting procedure nine samples of al-alloy (4032) with dimensions of (60 x42 x 12) mm were prepared as a block. then, the nine samples of al-alloy (4032) were machined again by an end mill cutter into three lines of each sample, as shown in figure (5). fig. 5. cutting procedure using cnc vertical milling machine system for al-alloy (4032) samples. 3. measurements 3.1 surface roughness (ra) surface roughness was measured on all cutting surfaces of all samples using pocket surf the portable roughness of the surface gauge mahr federal's patent. four readings were taken from the (ra) instrument for each machining line of sample, and the average value of the four readings was recorded. figure 6 shows the instrument used in the experiments, and the results were presented in the table (6). fig. 6. measurement of surface roughness. 3.2 metal removal rate (mrr) the material removal rate was used, which is the important factor of production rate in the milling process used in optimization criterion, to calculate material removal rate applied by equation (1) and the results were presented in the table (6) [6,10]. 𝑀𝑅𝑅 𝑛 ∗ 𝑁 ∗ 𝑓 ∗ 𝑑𝑐 ∗ 𝑑 … 1 where (n is spindle speed in r/min, n is tool flutes, ft is feed rate in mm/tooth, dc is depth of cut in mm and dt is width of cut in mm (diameter of tool)). 3.3 micro-hardness the vickers micro-hardness instrument was used in this study, and hardness micromeasurement was performed at three locations along each line of milled surface samples, with the average value considered for further analysis using the automatic micro hardness tester as shown in figure (7). this device operates on the concept of impressing a diamond in the shape of a  sami abbas hammood al-khwarizmi engineering journal, vol. 17, no. 3, p.p. 112 (2021)    6   square-based pyramid onto the examined surface of a load-bearing material. the hardness testing was done by taking a 200 g indentation load with a dwell time of 15 s. the results are presented in the table (6). fig. 7. digital micro-hardness tester. table 6, experimental results of measured outcomes quality characteristics. test no. levels of control factors ra(µm) mean mrr (mm3/min) surface hardness hv0.2 type of tool (a) spindle speed (b) r.p.m feed rate (c) mm/tooth depth of cut (d) mm 1 h.s.s 2000 0.03 0.5 2.344 1680 159.45 2 3000 0.06 1 3.141 10080 154.32 3 4000 0.1 1.5 3.442 33600 167.19 4 h.s.s coated with tin 2000 0.06 1.5 3.925 10080 178.27 5 3000 0.1 0.5 2.204 8400 148.63 6 4000 0.03 1 1.964 6720 151.54 7 carbide-titanium 2000 0.1 1 2.678 14000 163.72 8 3000 0.03 1.5 2.017 9450 140.81 9 4000 0.06 0.5 1.883 8400 143.39 4. analysis methods to estimate optimal cutting parameters (results and discussion) 4.1 grey relational analysis the gra is a method for determining and clarifying relationships among multiple responses. the grey relational analysis consists of four steps, as detailed below [1-6,10-16]: 1grey relational generation, which normalizes outputs in the range (0 to 1), this step is known as data pre-processing by input the experimental results to calculate gra performance characteristic. for the grey relational generation, there are two forms of data pre-processing. surface roughness and micro-hardness data pre-processing, which has the lower-the-better performance characteristic, it is possible to express as follows in this equation. 𝑋∗ 𝑘 max 𝑋 𝑘 𝑋 𝑘 max 𝑋 𝑘 𝑚𝑖𝑛𝑋 𝑘 … 2 the metal removal rate data pre-processing, which has a higher-the-better performance characteristic, can be described as follows:  sami abbas hammood al-khwarizmi engineering journal, vol. 17, no. 3, p.p. 112 (2021)    7   𝑋∗ 𝑘 𝑋 𝑘 𝑚𝑖𝑛𝑋 𝑘 max 𝑋 𝑘 𝑚𝑖𝑛𝑋 𝑘 … 3 where i is the test number, from 1 to 9; 𝑘 represents the 𝑘th performance characteristic ; 𝑋∗ 𝑘 is the normalized value; 𝑋 𝑘 is the original value; 𝑚𝑖𝑛𝑋 𝑘 is the smallest value of 𝑋 𝑘 and max 𝑋 𝑘 is the largest value of 𝑋 𝑘 . 2grey relational coefficients, which is an equation for expressing the relationship between ideal and true normalized experimental outcomes. this is how the grey relational coefficient is expressed: 𝜉 𝑘 δmin ε δmax ∆ 𝑘 ε δmax … 4 where δmin is the minimum value of δoi in this study which is equal to (0); δmax is the maximum value of δoi in this study which is equal to (1); ∆ 𝑘 the deviation sequence determine using the equation ∆ 𝑘 ‖𝑋∗ 𝑘 𝑋∗ 𝑘 ‖, ε is a positive number (0, 1). the value of ε may be changed to fit the needs of the service users, and a smaller value of ε means better distinguishing ability. in this study, ε was set to 0.5. 3determine the grey relational grade, which adds a grade to each of the coefficients for each performance attribute in order to rank the experiments. 𝐺𝑅𝐺 1 𝑛 𝜉 𝑘 … 5 where n denotes the number of output characteristics (n = 3 in this study) and the results of grey relational analysis for three steps showed in tables (7and 8). table 7, normalized and deviation values from grey relational generation of output. test no. normalized values of output deviation values of output ra mrr hardness hv0.2 ra mrr hardness hv0.2 1 0.774 0.000 0.502 0.226 1.000 0.498 2 0.384 0.263 0.639 0.616 0.737 0.361 3 0.237 1.000 0.296 0.763 0.000 0.704 4 0.000 0.263 0.000 1.000 0.737 1.000 5 0.843 0.211 0.791 0.157 0.789 0.209 6 0.960 0.158 0.714 0.040 0.842 0.286 7 0.611 0.386 0.388 0.389 0.614 0.612 8 0.934 0.243 1.000 0.066 0.757 0.000 9 1.000 0.211 0.931 0.000 0.789 0.069 table 8, grey relational coefficients and grades with ranking. test no. grey relational coefficients grey relational grade rank ra mrr hardness hv0.2 1 0.689 0.333 0.501 0.509 6 2 0.448 0.404 0.581 0.478 8 3 0.396 1.000 0.415 0.604 5 4 0.333 0.404 0.333 0.357 9 5 0.761 0.388 0.705 0.618 4 6 0.926 0.373 0.636 0.645 3 7 0.562 0.449 0.450 0.487 7 8 0.884 0.398 1.000 0.761 1 9 1.000 0.388 0.879 0.756 2 setting (0.5, 0.5,0.5) 4rank deduction of each grey relational grade according to the higher value: the grey relational grade for each test using the l9 orthogonal array depending on minitab software is shown in table 8. the product quality improves as the grey relational grade increases. as a result, the factor influence can be calculated and the optimum level for each controllable factor can be determined using grey relational grade. table 9 describes and shows the mean of the grey relational grade for each level of the parameter. in addition, for each of the nine tests, the total mean  sami abbas hammood al-khwarizmi engineering journal, vol. 17, no. 3, p.p. 112 (2021)    8   of the grey relational grade is estimated and described in table 9. the grey relational grade chart for the levels of the processing parameters is as seen in figure 8. the higher the grey relational grade, which leads to the greater the multiple output characteristics. however, the relative value of the parameters for the multiple output characteristics would need to be known in order to effectively calculate the optimum combinations of the method parameter levels [1-6,10-16]. table 9, mean grey relational grade. level tool spindle speed feed rate depth of cut 1 0.5303 0.4511 0.6383 # 0.6277 # 2 0.5400 0.6188 0.5301 0.5365 3 0.6677 # 0.6681 # 0.5695 0.5738 delta (max – min) 0.1375 0.2169 0.1082 0.0911 rank 2 1 3 4 mean grey relational grade of all levels = 0.5793 # optimal level of each parameter fig. 8. main effects chart of the grey relational grade to the levels of the processing parameters. 4.2 analysis of variance (anova) anova is a statistical tool for determining the percentage contribution of each important variable to the operation response. the main objective of anova is to show which operation parameter has a major effect on performance characteristics. a higher percentage of contribution means that the factor has a larger effect on output characteristics [1-7,10,11,15-18]. table 10 shows the anova outcomes for the grey relational grade and the contribution percentages of each operation variable in order of importance. table 11 shows the definition symbols and description found in anova. table 10, the anova outcomes. source df ss adj ms f p pc % tool 2 0.0353 0.0177 1.737 0.429 24 spindle speed 2 0.0776 0.0388 4.223 0.214 52.75 feed rate 2 0.018 0.009 0.723 0.629 12.23 depth of cut 2 0.0126 0.0062 0.407 0.728 8.57 error 2 0.0036 0.0018 2.45 total 10 0.1471 100.00  sami abbas hammood al-khwarizmi engineering journal, vol. 17, no. 3, p.p. 112 (2021)    9   table 11, the symbols and description found in analysis of variance. symbol meaning description df degrees of freedom from each factor if a factor has three levels, the degrees of freedom is 2 (n-1) ss sum of squares the sum of squares between groups (factor) and the sum of squares within groups (error) adj ms mean squares can be found by dividing the sum of squares by the degrees of freedom p probability use to determine whether a factor is significant f fisher ratio (variance ratio) calculated by dividing the factor ms by the ms error pc % contribution percentages of each factor calculated by dividing the ss of each factor to total of ss and use to determine whether a factor is significant 4.3 confirmation test (optimal test) the confirming test is the last step in the process of predicting the output characteristic using the optimum combination of operation factors and ensuring the efficiency and repeatability of the optimization approach used in this analysis. the following equations can be used to estimate the predicted grey relational grade in the desired condition [1-5,11,15]: 𝑔 𝑔 𝑔 𝑔 … 6 where g mean is the total mean of the grey relational grade (0.5793), gi is the mean grey relational grade at the optimum level, and q is the number of the operation parameters that significantly affect the multiple performance characteristics (the major influencing parameters on multi-objective response are spindle speed and cutting tool with grey relational grade at high level are 0.6677and 0.6681, respectively). therefore 𝒈𝒑𝒓𝒆𝒅𝒊𝒄𝒕𝒆𝒅 0.5793 + (0.66770.5793) + (0.66810.5793) = 0.7565. table 12 shows a comparison of the predicted grey relational grade using favored operation parameters, experimental grey relational grade using favored operation parameters (a3 b3 c1 d1), and experimental grey relational grade using original operation parameters (a3 b2 c1 d3). in addition, the outcomes of the confirmation experiment using the optimum machining parameters are shown in table 12. the material removal rate (mrr) is reduced from 8400 to 4200 mm3/min , the surface roughness (ra) and microhardness (hv0.2) are reduced from (2.017 to 1.742 μm) (140.81 to138.34 hv 0.2 ) respectively, with the grey relational grade increased from 0.761 to 0.784 (2.3% improvement). this indicates that the optimum combination of milling process parameters is sufficient to cover the requirement of surface quality (reduced surface roughness and micro-hardness), but the productivity (max metal removal rate) is reduced because in this study the metal removal rate is quantity value depended on end milling process parameters and number of flute for tool according equation (1). table 12, the outcomes of the confirmation experiment using the optimum machining parameters. original process parameters favored process parameters prediction experiment level setting a3 b2 c1 d3 a3 b3 c1 d1 a3 b3 c1 d1 surface roughness 2.017 μm 1.742 μm material removal rate 8400 mm3/min 4200 mm3/min micro-hardness 140.81 hv0.2 138.34 hv0.2 grey relational grade 0.761 0.7565 0.784 5. conclusions the combined taguchi method and grey relational analysis were used to provide an efficient methodology for optimizing the end milling operation of al-alloy (4032) with multiperformance outputs. the following conclusions can be taken from the results of this study: 1the results of anova showed that the major influencing parameters on multi-objective response were spindle speed and cutting tool (type of material and no. of flutes) with  sami abbas hammood al-khwarizmi engineering journal, vol. 17, no. 3, p.p. 112 (2021)    10   contribution percentage (52.75%, 24%), respectively, while the minor influencing parameters on multi-objective response were feed rate and depth of cut with contribution percentage (12.23%, 8.57%), respectively. 2the optimal combination of end milling operation parameters and their levels for the end milling process's optimal multiperformance characteristics are a3 b3 c1 d1 (i.e tool no.3, spindle speed = 4000 m/min, feed rate = 0.03 mm/tooth and cutting depth = 0.5 mm). 3the results of the confirmation experiment using the optimum machining parameters are the material removal rate (mrr) is reduced from 8400 to 4200 mm3/min, the surface roughness (ra) and micro-hardness (hv0.2) are reduced (from 2.017 to 1.742 μm) and (from 140.81 to138.34 hv 0.2), respectively with the grey relational grade increased from 0.761 to 0.784 (2.3 improvement percentage). 6. references [1] s. ajith arul daniel, r. pugazhenthi, r. kumar, s. vijayananth, "multi objective prediction and optimization of control parameters in the milling of aluminum hybrid metal matrix composites using ann and taguchi-grey relational analysis," defence technology, vol. 15, no.4, pp. 545-556, 2019 . 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[15] pankul goel, zahid a. khan, arshad noor siddiquee, shahrul kamaruddin, rajeev kumar gupta., "influence of slab milling process parameters on surface integrity of hsla: a multi-performance characteristics optimization," the international journal of advanced manufacturing technology, vol. 61, pp.859–871, 2012. [16] c. c. tsao. "grey–taguchi method to optimize the milling parameters of aluminum alloy," the international journal of advanced manufacturing technology, vol. 40, pp.41-48, 2009 . [17] aqeel sabree bedan, halah ali habeeb, "an investigation study of tool geometry in single point incremental forming (spif) and their effect on residual stresses using anova model," al-khwarizmi engineering journal, vol. 14, no.2, pp. 113, june. 2018. [18] aseel jameel haleel,"optimization drilling parameters of aluminum alloy based on taguchi method," al-khwarizmi engineering journal, vol. 14, no.2, pp. 14 21, june. 2018.  )2021( 112 صفحة ، 3العدد ،17المجلد الهندسية الخوارزمي جلةم عباس حمودسامي   12   مع تاكوشي طريقةباستخدام ) 4032امثلية متغيرات عملية القطع بالتفريز لسبيكة المنيوم ( الرمادي العالئقي التحليل سامي عباس حمود بغداد /قسم هندسة اإلنتاج والمعادن / الجامعة التكنولوجية sami.a.hammood@uotechnology.edu.iq :البريد االلكتروني الخالصة جات المتعددة الهدف من هذا العمل هو دراسة تأثير متغيرات عملية القطع بالتفريز، باإلضافة إلى مادة والشكل الهندسي لعدة القطع على استجابة المخر . تم (grey relation analysis) الرمادي العالئقي التحليل مع تاكوشي طريقة). يمكن القيام بذلك عن طريق اقتراح نهج يجمع بين 4032لسبيكة المنيوم ( د وشكل هندسي اختيار ثالث متغيرات للقطع (سرعة القطع ، معدل التغذية وعمق القطع) مع ثالثة مستويات لكل متغير. كما تم استخدام ثالث عدد قطع بموا . يتم حل استجابة العديد من خصائص اإلخراج لعملية القطع l9مختلف (عدد الحدود القاطعة) لتصميم االختبارات التجريبية والتشغيل بناًء على المصفوفة درجة على باالعتماد عن (grey relation grade) الرمادي العالئقي التحليل بالتفريز grey relation) الرمادي العالئقي التحليل الناتجة analysis) أظهرت نتائج تحليل التباين . )anova (الرمادي العالئقي التحليل على درجة باالعتماد (grey relation grade) أن العوامل الرئيسية القاطعة الحدود وعدد المادة (نوع القطع وعدة القطع سرعة هي األهداف متعددة المخرجات استجابة على الكلية المؤثرة العملية من مساهمة نسبة مع ( ٪) على التوالى .باإلضافة إلى ذلك ، تم التحقق من صحة التركيب االمثل لمتغيرات عملية القطع بالتفريز التي تم الحصول عليها من خالل ٢٤٪ ، ٧٥,٥٢( د تحديد التحسن في استجابة المخرجات المتعددة . اظهرت عن طريق إجراء اختبار نهائي لتأكي (grey relation analysis) الرمادي العالئقي التحليل الرمادي العالئقي التحليل) مع درجة mrrلمعدل إزالة المعدن ( اختبارات التأكيد للحصول على الحد األدنى من (خشونة السطح والصالدة) والحد األقصى (grey relation grade) )٢٫٣) و نسبة التحسن ( ٠٫٧٨٤ .(٪ this is an open access article under the cc by license tracked robot control with hand gesture based on mediapipe marthed wameed* ahmed m. alkamachi** ergun erçelebi*** *,**department of mechatronics engineering/ al-khwarizmi college of engineering/university of baghdad/ baghdad/iraq *** department of electric and electronic engineering/ gaziantep university/ turkey corresponding author: *email: marthad.wameed1202a@kecbu.uobaghdad.edu.iq ** email: ahmed78@kecbu.uobaghdad.edu.iq *** email: ercelebi@gantep.edu.tr (2023april 26 accepted; 2022 mbernove 23 received) https://doi.org/10.22153/kej.2023.04.004 abstract hand gestures are currently considered one of the most accurate ways to communicate in many applications, such as sign language, controlling robots, the virtual world, smart homes, and the field of video games. several techniques are used to detect and classify hand gestures, for instance using gloves that contain several sensors or depending on computer vision. in this work, computer vision is utilized instead of using gloves to control the robot's movement. that is because gloves need complicated electrical connections that limit user mobility, sensors may be costly to replace, and gloves can spread skin illnesses between users. based on computer vision, the mediapipe (mp) method is used. this method is a modern method that is discovered by google. this method is described by detecting and classifying hand gestures by identifying 21 three-dimensional points on the hand, and by comparing the dimensions of those points. this is how the hand gestures are classified. after detecting and classifying the hand gestures, the system controls the tracked robot through hand gestures in real time, as each hand gesture has a specific movement that the tracked robot performs. in this work, some important paragraphs concluded that the mp method is more accurate and faster in response than the deep learning (dl) method, specifically the convolution neural network (cnn). the experimental results shows the accuracy of this method in real time through the effect of environmental elements decreases in some cases when environmental factors change. environmental elements are such light intensity, distance, and tilt angle (between the hand gesture and camera).the reason for this is that in some cases, the fingers are closed together, and some fingers are not fully closed or opened and the accuracy of the camera used is not good with the changing environmental factors. this leads to the inability of the algorithm used to classify hand gestures correctly (the classification accuracy decrease), and thus response time of the tracked robot's movement increases. that does not present possibility for the system to determine whether the finger is closed or opened. keywords: computer vision, machine learning, mediapipe, hand landmarks. 1. introduction hand gestures at the present time play an important role in communication between humans and robots. also, hand gestures have developed significantly, as they were previously used in specific fields but are now used in wide fields, for example, in smart cars, video games, and smart homes. in addition, hand gestures is very widely used in translation to communicate between people who have difficulty speaking or hearing [1].in this paper, the computer vision algorithm, specifically the machine learning algorithm (mediapipe), is utilized. the techniques of turning images into digital data and altering their nature so that they are easier for machines to grasp while simultaneously al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 19, no. 3, september, (2023) p. p. 5671 mailto:marthad.wameed1202a@kecbu.uobaghdad.edu.iq mailto:ahmed78@kecbu.uobaghdad.edu.iq mailto:ercelebi@gantep.edu.tr https://doi.org/10.22153/kej.2023.04.004 marthed wameed al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 5671 (2023) 57 enhancing the visual information and human perception of it are known as computer vision [2]. computer vision is the only technique that can extract information from incoming images [3]. the mediapipe algorithm is used to detect and classify the hand gestures [4]. the goal in this research is to detect hand gestures using the mp algorithm via the camera sensor, classify hand gestures, and transmit the instructions wirelessly. that is to the tank robot to perform certain movements, as each hand gesture indicates a specific movement in the tank robot. there are other ways to detect and classify hand gestures using deep learning, specifically convolutional neural networks (cnn) [5-11]. this method is more complex and consumes more processing time. the main research contribution in this manuscript is to improve the mediapipe algorithm in a way that gives the fastest response in classifying hand gestures. that is by making the hand detection only runs on first frame or when hand is missing in an image. that can significantly reduce response time and make the algorithm more accurate in detect hand gestures. 2. related work in this section, a summary of previous studies are provided. hand gesture is one of the important topics in our world and is defined as a non-voice communication through which hand movement can be used to transmit instructions to multiple devices without direct contact with those devices. waskito et.al.[12] depended on deep learning to detect hand gestures in real time by using the convolutional neural networks (cnn) and then control the movement of wheeled robot via hand gestures. huu et. al. [13] used artificial neural network (ann) to detect hand gesture and control the smart home in real time via these gestures. bidyut juoti et. al. [14], used the machine learning specifically uses media pipe to detect hand gesture to control computer mouse through these hand gestures. in mp, hand gestures were detected by two faces. the first was the hand detection via palms detector and the second was the hand landmark via 21 three dimensional points on every part of the hand gesture as shown in the figure (1) [4]. subhangi adhikary et.al [15] saved the new data which contains 21 points on every part of the hand gesture in a file called csv, and this data were used to train and test the system. mp process reduced the use of data augmentation (i.e. rotations, flipping, scaling) used in deep learning [16]. prakash et.al. [17] detected hand gestures by fingertips to control mouse operations in the computer in real time using the camera. the region of hand was first segmented using the increasing area technique and then applying morphological operations.haldera et. al. [16] utilized machine learning algorithm and mp ś opensource framework to detect sign language and to test this system they use several data for sign language such as american, italian, indian and turkish. ali suryaperdana agoes et. al.[18]employed hand gestures to control a user guide application through mp's open source framework .by comparing the value of coordinates points of the fingers and detecting the finger, closed or opened. if the coordinates value of fingertip's was higher than the finger middle points, set the finger with a value of 1, meaning the finger was in the open condition, and vice versa. taban et.al.[19] depending on the computer vision, specifically the use of the violajones algorithm to detect and classify hand gestures, and through these gestures, the lights are turned on and off. the lighting response time to the gesture commands was 0.43 seconds, and the dataset consisted of eight gestures containing 12000 images. in this work, for more efficient and precise computer training, a novel concept proposes using skin detection prior to computer training to automatically establish the size and position of all positive pictures. marthed wameed al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 5671 (2023) 58 a b fig. 1. a. hand gestures detection [20]. b. hand landmarks. 3. system design 3.1. general design figure (2) shows the main parts of the system. the system consists of two main parts. 1. base station as shown in figure (3) images of hand gestures are captured in real time by a camera (avermedia pw313) connected to a microcontroller (raspberry pi 4). the camera and the microcontroller detect and classify hand gestures based on computer vision. next, the output commands are sent via bluetooth to the robot to execute these commands. each hand gesture has a specific command that moves the robot according to those commands, as shown in table 1. fig. 2. overall system description. marthed wameed al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 5671 (2023) 59 table 1, the style of hand motions and directives used. fig. 3. base station parts description. pycharm, the python programming language, the opencv, proposed model, and tensorflow libraries are used in the software design for preprocessing and picture classification in machine learning. 2. tracked robot as shown in figure (4) the tracked robot contains several parts, and among these parts is the microcontroller (arduino mega). the microcontroller receives commands for moving the robot from the bluetooth connected to itself and sends those commands to a dc driver (motor driver bts7960). the speed and rotation of the dc motors are controlled. whereas, the dc motors are responsible for the movement of the tracked robot. the robot also contains four ultrasonic sensors to avoid obstacles and be more accurate in its movements. the form of hand gestures 0 1 2 3 4 5 the commands executed in the robot stop (robot is not moving) move forward move backward left (rotating anti clockwise) right (rotating clockwise) stop (robot is not moving) marthed wameed al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 5671 (2023) 60 fig. 4. tracked robot parts description. figure (5) shows the complete process flowchart of the system’s work, starting with taking pictures with the camera, passing through the stages of detecting and classifying hand gestures, and leading to controlling the tracked robot’s movement through hand gestures. marthed wameed al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 5671 (2023) 61 fig. 5. software design flowchart. 3.2 mediapipe framework in july of 2019, google published mediapipe as an open-source tool. this method detects the palm with the use of single shot detection (ssd), an object identification technique (detection the palm), and the hand landmark model is used to extrapolate the information necessary to recognize the fingers. the mediapipe is an algorithm that detects individual hands inside a video stream. the algorithm is developed using machine learning techniques. real-time hand tracking is possible by using mediapipe for everyone with a webcam. by using machine learning, technique in this study extrapolates 21 points 3d from a single picture. real-time tracking of several hands is made possible by a three-stage approach consisting of a palm detection model, a hand landmark model and gesture recognizer model as shown in figure (6) [20-23]. the three models, as well as the training datasets, are detailed in more depth below. fig. 6. mp algorithm parts. marthed wameed al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 5671 (2023) 62 3.2.1 datasets three distinct data sets are selected for use in the training of the mediapipe models. the description of the datasets that are used in the training of the model is listed below.  the wild dataset: this dataset contains 6,000 pictures that vary greatly in regard to factors like location, lighting, and the way people's hands look. one drawback of the dataset is that it doesn't capture more complex forms of hand articulation. ● the house collected dataset: there are around 10,000 images in this collection, each showing a different hand movement from every possible angle. the disadvantage of this dataset is that it was collected from just 30 persons, and there was very little variation in the backgrounds of those people.  synthetic dataset: this dataset takes a highresolution representation of a synthetic hand model and maps it to its 3d coordinates against a variety of backgrounds. five skin tones are included in the hand model's texturing. one hundred thousand still images were captured from the change video streams between hand positions. three cameras were used to capture each pose in a randomly generated high dynamic range lighting scenario. 3.2.2. palm detector model compared to other tasks, detecting hands is more difficult since it must be able to distinguish between different hand sizes and recognize closed portions of hands. it is possible to use the contrast and forms of a person's nose and lips as distinguishing traits in a face detection activity. in contrast, comparable traits are absent in the hand detection task, significantly increasing its difficulty. thus, the palm detection is trained since it is simpler to estimate bounding boxes around stiff objects like the palm and the fist [22]. 3.2.3. hand landmark after revealing the palm detector model, the landmark stage comes. the 21 three-dimensional points are identified on the hand, as shown in figure (6).where the x-axis represents the width of the image, the y-axis represents the height of the image, and the z-axis represents the depth of the image (the distance between the hand and camera).comparing between the dimensions of 21 points 3d, the hand gestures are classified. 3.2.4 gesture recognizer model figure (7) shows 21 points 3d on each part of the palm. to classify hand gestures, the value of coordinates of the points (4, 8, 12, 16, 20) are compared. these points represent the fingertips with the value of coordinates of the points (3, 5, 9, 13, 17) that represent the middle points relative to the x and y axes. ● the state of the thumb. the thumb is open if the value of coordinate of the point (4), (which represents fingertip ) relative to the x-axis, is greater than the value of coordinate of the point (3), (which represents the middle point) relative to the x-axis, and vice versa. ● second, the state of the all fingers except for the thumb. the fingers (index, middle, ring, and pinky) are opens if the values of coordinates of the points (8, 12, 16, 20), (which represent the fingertip) relative to the y axis are greater than the values of coordinates of the points (5, 9, 13, 17),(which represent the middle point) relative to the y axis, and vice versa. fig. 7. hand landmark [20]. marthed wameed al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 5671 (2023) 63 figure (8) illustrates the graph that we created in mediapipe in order to monitor hand movements. the graph is segmented into two parts: one to detect hands and another to calculate landmarks [22]. one of the main improvements provided by mediapipe is the palm detector, which only executes when required (which isn't very frequently) and therefore dramatically lowers computing costs. instead of using the palm detector on every frame, we accomplish this by determining the hand location in the current video frames from the computed hand landmarks in the previous frame. the main contribution in this manuscript is to improve the mediapipe algorithm in a way that makes it the fastest response in detecting hand gestures in real time by making the hand detection only run on the first frame or when the hand is missing in the image. which significantly reduces response time and makes the algorithm more accurate at detecting hand gestures. fig .8. stricture of mp algorithm. 4. description of the data sets for testing proposed model mediapipe is capable to recognize significantly more complicated gestures. six distinct hand gestures are distinguished by the number of raised fingers are identified in this work. these results are categorized into six classes and distinguished by the number of fingers raised (from 0 to 5) as shown in figure (9). figure (9) lists six gestures that are employed to assess hand gesture detection. initial images for the data collecting phase are captured using the laptop's webcam. due to the low quality of the captured photos caused by noise, the information are re-collected using aver pw313 webcam. all of these photos are shot in different lighting scenarios. five hundred pictures are taken for each class, half in the sunlight and half at night using the standard lamp in the room. the hands' locations (distance between camera and gesture) and angles (between camera and gesture) are also altered. marthed wameed al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 5671 (2023) 64 fig .9. explain the dataset consist of six classes. 5. configuration settings of mediapipe algorithm there are a variety of configuration settings that may be applied. the configuration are explained below: static_image_mode: a flag that can be used to determine which mode will be utilized while reading the image. in this study, the proposed model are tested in two modes  default mode, depending on the data set that are previously collected for testing the proposed model.  undefault mode depending on the data set from real time for testing the proposed model. max_num hands: depending on the number of hands being examined, a value for this integer variable must be determined. for this work, the default value of 2 is used. model_complexity: this flag indicates the accuracy and response time. if the value is 1, this indicates that the system works with high accuracy, but with a longer response time. if it is 0, it indicates the opposite. in this work, the value was set to the default value, which is 1. min_detection_confidence: this is the level of confidence that the hand detector uses to set the output threshold. if the confidence is less than this provided threshold value, the detectors is considered to have failed, and also no output is given. the number must be between 0.0 and 1.0. in this work, the default value of 0.5 is utilized. mim_tracking_confidence: the static mode does not make use of this flag. when performing real-time hand tracking, this value should be set between zero and one. this is done to ensure that the hand is successfully monitored. this uses the default of 0.5. during live tracking, if the confidence is too low, it will move on to the next image without doing the detection. hand detection is performed on each and every image in static mode [20]. 6. experimental results 6.1 accuracy of proposed model algorithm when static image mode is default without control robot table (2) details mp's classification report, and figure (10) displays the outputs images. the accuracy of proposed model is 0.97. that has a recall and precision of 0.90 and 0.91, respectively. also, the f1 score is 0.90. the f1-score for each classes is shown in figure (10). additionally, environmental settings such as the distance between hand gestures and the camera being 1 m and the tilt angle between hand gestures and the camera being 0° have been specified. marthed wameed al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 5671 (2023) 65 fig. 10. clarify f1-score of different classes. table 2, classification report. classes precision s𝑒𝑛𝑠𝑖𝑡𝑖𝑣𝑒𝑡𝑦 (𝑅𝑒𝑐𝑎𝑙𝑙) accuracy f1-score 0 0.97 0.9 0.98 0.93 1 0.96 0.96 0.99 0.96 2 0.90 0.97 0.97 0.93 3 0.81 0.73 0.95 0.76 4 0.83 0.85 0.95 0.83 5 0.93 .990 0.98 0.95 mean 0.91 0.90 0.97 0.89 fig. 10. results of the proposed model algorithm through the above table, the highest value of accuracy is represented in class 1, and the lowest accuracy is represented by classes 4 and 3, is noted.the accuracy of the classification of hand marthed wameed al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 5671 (2023) 66 gestures depends on the comparison between the dimensions of the points (21 points 3d). in some cases, the fingers are close together, and some fingers are not fully closed or opened, which leads to the inability of the algorithm used to classify hand gestures correctly, and thus the classification accuracy decreases. 6.2. test the proposed model when static image mode is undefault to control the robot in real time depending on the changing intensity of illumination, the accuracy of the system is calculated this is the first testing for the proposed system. a specific application is used to measure the intensity of lighting based on the phone's camera. in this research, lighting with a variable intensity that is 50 lux, 100 lux, and 150 lux, has been used. additionally, environmental settings such as the distance between hand gestures and the camera being 1 m and the tilt angle between hand gestures and the camera being 0° have been specified. the experiment is repeated 20 times for each hand gesture and light intensity. table 3, light intensity variation based accuracy. hand gesture accuracy with intensity light (%) 50 lux 100 lux 150 lux stop 100 100 100 forward 100 100 100 backward 100 100 100 left 75 100 65 right 65 100 40 according to table (3), when the illumination level is set to 100 lux, the accuracy for all hand gestures reaches 100%. depending on the changing the distance between camera and hand gestures, the accuracy of the system is calculated. this is the second test for the proposed system. the measurement distance is the distance between the hand gestures and the camera. the distances chosen are 1 m, 2 m, and 4 m. additionally, environmental settings such as the intensity of light being 100 lux and the tilt angle between hand gestures and the camera being 0° have been specified. experiment is repeated 20 times for each hand gesture and specified distance. table 4, variations in distance-based accuracy. hand gesture accuracy with distance (%) 1 m 2 m 4m stop 100 100 100 forward 100 100 100 backward 100 100 100 left 100 80 70 right 100 70 70 table (4) shows that at 1 m, the accuracy reaches 100% for all hand gestures. this means that at this distance, all hand gestures can be correctly classified. depending on the changing tilt angle between camera and hand gestures as shown in figure (11). the accuracy of the system is calculated. this is the second testing for the proposed system. fig. 11. the tilt angles between the hand and the camera. the tilt angle used between the hand gesture and the camera is 0°, 30°, 60°and 90° in this test. additionally, environmental settings such as the distance between hand gestures and the camera being 1 m and intensity of light being 100 lux. each hand gesture and tilt angle is tested 20 times. marthed wameed al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 5671 (2023) 67 table 5 tilt-angle testing accuracy. table (5) shows high accuracy values, with 100% for each hand gesture when the slope angle is 30° degrees or 0° degrees. 6.2.1 actuators power consumption test two electric motors (6v, dc) are used to move the tracked robot, while a 2,200-mah, 14.8-volt li ion battery is used to power the motors. various hand gestures have different pwm values. table 7, actuators power consumption test for each pulse width modulator (pwm). hand gesture left motor right motor pwm consumed power(w) pwm consumed power(w) stop 0 0 0 0 forward 38 0.808 38 0.8602 backward 38 0.8064 38 0.808 left 29 0 29 0.6768 right 29 0.633 29 0 using current sensor (ina219) to measure consumed power in the above table, a slight difference in the value of consumed power for the same value of pwm between the right and left motors is noticed. this difference is due to the distribution of loads in the robot. 6.2.2 time response time testing checks how long it takes from when the input is given until the output is run. hand gestures are used as input, and the robot's motors move as a result. the response time is calculated from the time the input is given, and then the raspberry pi 4 processes the data and sends the data to the robot motors via bluetooth. after that, each hand gesture undergoes a test of response time. each hand gestures is tested 3 times. table 8, the robotic response time test. hand gesture average reaction time (s) stop 0.091 forward 0.121 backward 0.126 left 0.162 right 0.165 average total reaction time (s) 0.133 table (8) shows that the average time it takes for hand gesture input to trigger motor action on the robot is 0.133 seconds. table (9) shows the comparison of the state-ofthe-art works of waskito et.al. [12], huu et. al.[13], bidyut juoti et. al. [14], subhangi adhikary et.al [15], a. halder et.al [16], prakash et.al. [17], ali suryaperdana agoes et. al. [18] with the model we suggested, which delivered more accurate and better results. hand gesture accuracy with tilt angle (%) 0° 30° 60° 90° stop 100 100 100 60 forward 100 100 100 30 backward 100 100 100 20 left 100 100 55 15 right 100 100 40 12 marthed wameed al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 5671 (2023) 68 table 9, comparison of the state-of-the-art works with our proposed model. accuracy (%) data set neural network architecture sensors objective reference 96.67% 6000(training) 600(validation) cnn single camera wheeled robot control waskito et.al. [12] 91.5% 6000(size352x200) 6000(size 704x400) ann single camera smart home control huu et. al.[13] from google enormous and diverse machine learning (mediapipe) webcam virtual-mouse control bidyut juoti et. al. [14], 96.28%. 2194 machine learning (mediapipe and random forest classifier) single camera communicating between people (disabilities) subhangi adhikary et.al [15] 96.22% 4124 machine learning (mediapipe and support vector machine svm) single camera communicating between people (disabilities)sign language (turkey) a. halder et.al [16], 95% 900 machine learning (mediapipe) kinect human-computer -interactions (hci)( user guide application) ali suryaperdana agoes et. al. [18] 97% 900 machine learning (mediapipe) single camera (avermedia pw313) movement robot control proposed model 7. discussion the accuracy of some commands decreases with changing environmental factors in real time. that is due to the system’s algorithm not being able to correctly classify hand gestures. the most important reason for the system’s inability to classify hand gestures correctly is that the fingers are close together and some fingers are not fully closed or opened. that may present a delay in the response of the robot's movement to some commands. thus, changing some irregular hand gestures to more regular gestures to increase accuracy and reduce the robot’s response time is recommended. 8. conclusion this study proposed a model to control the movement of the robot through hand gestures using computer vision, specifically relying on the mp algorithm. the mp algorithm classifies hand gestures by comparing the coordinates of 21 threedimensional points specified on the hand. the data sets used in this study for testing proposed model consisted of 30000 images of various hand gestures captured under various environmental conditions. through this model, the robot's movement was very well controlled, but there were some gestures that were not accurately classified in real time. the reason is due to the fact that some cases, the fingers are close together, and some fingers are not fully closed or open. that leads to the inability of the algorithm used to classify hand gestures correctly, and thus the classification accuracy decreases. that gives impossibility for the system to determine whether the finger is closed or opened. hence, the system depends on the classification of hand gestures based on the comparison between the coordinates of the 3d points specified on the hand. to increase the accuracy of the classification of hand gestures, suggestion of replacing these with others in which the fingers are more clearly defined. that leads to more accurate classification and thus reduces the response time of the robot to commands. in future work, a microcontroller can be used with high specifications for the application of computer vision algorithms, such as a jetson nano, as well as a high-resolution camera instead of the one currently used. marthed wameed al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 5671 (2023) 69 references [1] s. amaliya, a. n. handayani, m. i. akbar, h. w. herwanto, o. fukuda, and w. c. kurniawan, “study on hand keypoint framework for sign language recognition,” 7th int. conf. electr. electron. inf. eng. technol. breakthr. gt. new life, iceeie 2021, pp. 3–8, 2021, doi: 10.1109/iceeie52663.2021.9616851. 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(2023) 56-71، صفحة 3، العدد19مجلة الخوارزمي الهندسية المجلدمرثد وميض مجيد 71 عتماداً على الميديا بايبإيماءة اليد أ التحكم في الروبوت **القامجي احمد محروس مرثد وميض مجيد* لبي***چاركون ار بغداد / العراق /كلية الهندسة الخوارزمي/ جامعة بغداد *قسم هندسة الميكاترونيكس/،** عنتاب/ تركيا*** قسم الهندسة الكهربائية وااللكترونية/ جامعة غازي marthad.wameed1202a@kecbu.uobaghdad.edu.iq :البريد االلكتروني* ahmed78@kecbu.uobaghdad.edu.iq :البريد االلكتروني** ercelebi@gantep.edu.tr*** البريد االلكتروني: الخالصة ت، والعالم االفتراضي، تعتبر إيماءات اليد حاليًا واحدة من أكثر الطرق دقة وتطورا للتواصل في العديد من التطبيقات، مثل لغة اإلشارة، والتحكم في الروبوتا لتي تحتوي على عدة أجهزة استشعار أو والبيوت الذكية، ومجال ألعاب الفيديو. تُستخدم عدة تقنيات الكتشاف إيماءات اليد وتصنيفها، مثل استخدام القفازات ا ك لعدة أسباب منها اعتمادًا على رؤية الحاسوبية. في هذا العمل، سوف نعتمد على رؤية الحاسوبية بدالً من استخدام القفازات للتحكم في حركة الروبوت، وذل المرتبطة بالقفازات مكلفًا إذا تعرضت للتلف، الح اجهزة االستشعارأن استخدام القفازات يتطلب توصيالت كهربائية معقدة تقيد حركة المستخدم، وكذالك إص وهي طريقة حديثة تم اكتشافها mediapipeوأخيًرا القفازات معرضة لنقل األمراض الجلدية بين المستخدمين. بناًء على رؤية الحاسوبية يتم استخدام طريقة نقطة ثالثية األبعاد على اليد، ومن خالل مقارنة 21. يتم تلخيص هذه الطريقة من خالل الكشف عن إيماءات اليد وتصنيفها من خالل تحديد googleبواسطة أن كل إيماءة يد ، حيثأبعاد تلك النقاط، يتم تصنيف إيماءات اليد. بعد اكتشاف إيماءات اليد وتصنيفها، يتحكم النظام في حركة الروبوت من خالل إيماءات اليد أكثر دقة وأسرع في االستجابة mpلخصت بعض الفقرات المهمة إلى أن طريقه حركة معينة. في هذا العمل، بأداءلها امر محددة يقوم من خاللها الروبوت فعلي ان دقة هذه الطريقة من خالل تأثير (. أظهرت النتائج التجريبية في الوقت الcnnوتحديداً شبكة االلتفاف العصبية ) (،dlمن طريقة التعلم العميق ) ة والسبب في ذلك يرجع العناصر البيئية مثل شدة الضوء والمسافة وزاوية الميل )بين إيماءة اليد والكاميرا( تقل في بعض الحاالت عندما تتغير العوامل البيئي قارب االصابع او بعض أصابع اليد ليست مغلقة او مفتوحة بشكل كامل مما يؤدي إلى جودة الكاميرا المستخدمة وكذالك وضعيات ايماءات اليد الغير منتظمة )ت روبوت ، مما إلى عدم قدرة الخوارزمية المستخدمة في تصنيف إيماءات اليد بشكل صحيح )انخفاض دقة التصنيف(، وبالتالي زيادة وقت االستجابة لحركة ال غلقًا أم مفتوًحا.يجعل من صعب على النظام تحديد ما إذا كان اإلصبع م mailto:ercelebi@gantep.edu.tr this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 20, no. 1, march, (2024), p p. 1732 factors affecting electrocoagulation process for different water types: a review shahad fadhil abed al-rubaye* naseer a. alhaboubi** aiman h. al-allaq*** *,** department of chemical engineering /colleg of ingineering/ alnahrain university/ iraq ***old dominion university (odu)/ usa corresponding author: *email: shahad.fadhilma@gmail.com **email: naseer.a.alhaboubi@nahrainuniv.edu.iq ***email: aalal005@odu.edu (received 29 april 2023; accepted 16 october 2023; published 1 march 2024) https://doi.org/10.22153/kej.2024.10.001 abstract raw water must meet specific physical, chemical, and biological requirements to be suitable for drinking. there are various techniques available for treating wastewater, and aside from conventional methods that involve chemicals, electrocoagulation is an efficient and advanced approach. electrocoagulation has proven effective in treating many pollutants, including bacteria, viruses, iron, fluoride, sulfate, boron, hardness, and turbidity. total suspended solids, organic and inorganic materials, chemical oxygen demand cod, biochemical oxygen demand bod, and color. it finds extensive application in treating different types of water and wastewater due to its exceptional ability to remove diverse contaminants. recently, electrocoagulation has garnered significant attention due to its remarkable efficiency in treating various pollutants. this article provides a thorough analysis of contemporary literature that is committed to using electrocoagulation in a variety of water treatment methods, with a focus on the different variables affecting the process performance, such as electrical current, electrode type, electrode configuration, initial ph, electrode distance, nacl concentration, initial concentration of pollutants, operating temperature and electrolysis time. keywords: electrocoagulation, sulfate, iron, aluminum, anode, and cathode. 1. introduction one of a person's basic requirements is water, which is also a key component of any area's evolution. excess use of pesticides, herbicides, and fertilizers, leaky fuel and chemical tanks, chemical spills in industry, drainage of domestic chemical products, improperly managed landfills (groundwater assessment and its electrochemical treatment), suspended solids, biodegraded organic compounds, pathogens, nutrients, organic materials that are refractory, silica, heavy metals, and natural organic material nom are just a few examples of human activities that cause water pollution. direct sewage discharge into natural water bodies without treatment is not encouraged since the organic waste's degradation would significantly affect water quality. additionally, harmful microbes can spread infectious diseases. when nutrients like nitrogen and phosphorus, together with organic matter, are released into an aquatic environment, it can also promote the development of undesired aquatic life. when these nutrients are discharged excessively on land, it can also cause groundwater contamination [1]. using electricity to purify water was originally used in the uk in 1889 [2]. in 1946, the united states used electrocoagulation on a broad scale for the first time. due to its adaptability and low environmental impact, the electrocoagulation technique has garnered much interest in treating water [3] [4]. electrocoagulation, a treatment that is effective, economical, and favorable to the mailto:shahad.fadhilma@gmail.com mailto:naseer.a.alhaboubi@nahrainuniv.edu.iq mailto:aalal005@odu.edu https://doi.org/10.22153/kej.2024.10.001 shahad fadhil al-khwarizmi engineering journal, vol. 20, no. 1, p.p. 1732(2024) 18 environment, has received much attention lately. its unique features are its ease of use, minimal sludge generation, lack of extra chemical requirements, and effectiveness of the electrocoagulation process in removing toxins from water and wastewater. for removing pollutants, up to 99% removal efficiency has been observed using electrocoagulation [5]. electrocoagulation has shown to be quite efficient at removing various impurities from drinking water [6]. by substituting electrocoagulation for traditional chemical dosing, which involves adding primary coagulants such as ferric chloride or ferric sulphate, alum, aluminum chlorohydrate (ach), polyaluminum chloride (pac), or aluminum as the inorganic metal salt, settling is used to remove pollutants [7]. 2. electrocoagulation process 2.1 principles of electrocoagulation (ec) process method destabilizing dissolved, emulsified, or suspended pollutants in an aqueous media is done using electrocoagulation [8][5]. it combines chemical and physical treatments. it is an electrochemical process that uses the fundamental principles of conventional water treatment. in opposition to the coagulation technique, which involves adding coagulant particles to the pollutant to combine it, electrocoagulation employs electrodes to discharge the coagulant [9]. it has been successfully tested for cleaning municipal wastewater, textile wastewater, drinking water, poultry manure, landfill leachate oily water, and river and groundwater. this process is distinguished by its uncomplicated operation, simple equipment, lower reactive retention time, lack of equipment for chemical addition, and decreased sludge or precipitate levels that settle quickly [3]. electrochemical scale removal has various benefits, including environmental protection, eliminating the need to handle and administer chemicals, automation accessibility, and practical process management [10]. the biggest challenge is getting rid of the precipitated scale [11]. the ability to fully automate the process, a small treatment facility, cheap cost, and great particle removal efficiency. reduced sludge output, minimal chemical requirements, and simplicity of operation [12]. higher removal efficiency and a wider range of pollutants can be removed from an electrocoagulation unit than from a chemical coagulation due to the numerous processes that take place there [6] [8]. alum and ferric chloride are examples of common chemical coagulants that add counterions to the solution in addition to the metal cations that serve as the coagulant. compared to electrocoagulation, chemical coagulation necessitates handling more material. acid is produced substantially less by the electrochemical precipitation of iron or aluminum hydroxide than by chemical coagulation. on the contrary, creating these precipitates by electrocoagulation does not add any acid to the solution [13]. since electrocoagulation mostly comprises metallic oxides and hydroxides, it requires basic equipment, produces little sludge, and is very simple to dewater. chemical flocs are comparable to electrocoagulation flocs; however, electrocoagulation flocs are more stable, larger, and contain less bound water. as a result, settling and filtering can separate them more quickly. no more chemicals are utilized since the technique prevents their use. maintenance is minimal because the electrocoagulation process has no moving elements and is electrically controlled. in rural locations without access to power, it can also be used with solar energy. the disadvantages of electrocoagulation include the need to replace electrodes regularly because they dissolve, the high cost of power and anode passivation, and gelatinous hydroxides, which in certain situations tend to solubilize [5]. the electrocoagulation process has the following advantages over other chemical processes: compared to other chemical procedures, effluent has fewer total dissolved solids, is easy to operate, and degrades organic waste more quickly and effectively than chemical coagulation; compared to those produced by chemical coagulation, bigger and more stable flocs are developed; except in severe circumstances, controlling the ph of the water does not need the use of chemicals, lowers residue, it processes a variety of contaminants that are simple to remove, and its operating costs are far lower than those of most current technologies, the device may be utilized as a decentralized process since it is simpler and smaller than the coagulation device, and if solar panels are applied, in remote regions without access to power, the device can be utilized as a batch process to handle lesser amounts of waste water few of the drawbacks of electrocoagulation include the possibility of high power costs in some locations, the possibility of anode passivation related to oxygen present, and cathode deposition (can be overcome by shahad fadhil al-khwarizmi engineering journal, vol. 20, no. 1, p.p. 1732(2024) 19 changing the electrode poles), since the electrodes must be replaced frequently, raising maintenance expenses, high wastewater conductivity is necessary. it's necessary to eliminate the effluent's high quantities of iron and aluminum. while the gelatinous hydroxides may occasionally be dissolved in water, this method is ineffective for removing soluble materials, including solvents, organic acids, sugars, phenols, alcohol, and related compounds [14]. 2.2 mechanisms of ec method the electrocoagulation technique can generate coagulants on-site by electrochemically dissolving fe or al electrodes in an electrolyte solution to destabilize contaminants [15]. in the ec cell, as the electric current supplied to the electrochemical cell, the anode dissolves and produces metal cations [15]. during the procedure, current is transferred between electrodes and through an aqueous solution, producing metal ions on the site [6]. an applied voltage creates the coagulant species in situ as the sacrificial metal anode (aluminum or iron) dissolves [16][17]. since the sacrificial anodes corrode when an applied voltage is provided, electrocoagulation delivers the coagulants in place (lin al., n.d.). as the isoelectric point is reached, aluminum cations first help to neutralize the charge on the pollution particles. as with other charged polymeric metal hydroxide species, these cations can neutralize negatively charged particles. after being neutralized, aggregates or flocs may be created when the particles come together, which will remove the pollutants [5]. 2.3 theory of ec method in electrocoagulation (ec) for a continuous flow, the electrolytic gas produces a flotation action once the floc is produced, contaminants are removed from the floc-foam layer ;;; at the liquid's surface [3] (kabdaşlı et al., 2012) loose in aggregates are created as a result of the sorption coagulation action [16] (holt et al., 2004). it includes dissolving metal from the anode while producing hydroxyl ions, coagulant specie, that either precipitate and absorb dissolved contaminants or aggregate suspended particles [20][21] [22]. electro flotation removes extra impurities not eliminated in chemical coagulation due to the development of gas bubbles at both electrodes. like the coagulant salts employed in conventional chemical coagulation, such as alum and ferric chloride, the cations result from electrocoagulation, spontaneously forming polymeric metal hydroxide species in solution [5]. these metal ions combine to produce oxides and poly-oxyhydroxide complexes, which function as coagulants and can eliminate water pollutants. coagulation, electro-oxidation, electro-flotation, precipitation, adsorption, and settling are the mechanisms for removing contaminants due to the several operations that run concurrently in a single unit [6]. highly charged cations destabilize any colloidal particle by producing polyvalent polyhydroxide complexes. due to their strong adsorption abilities, these complexes combine with contaminants to create aggregates [3]. in ec, as time passes, more aluminum cation addition causes the precipitation of amorphous aluminum hydroxide, which encourages pollutant aggregation [16]. electrocoagulation involves a collision between negative oh ions and positive metal ions enhancing the creation of gelatinous hydroxide species. due to its gelatinous nature, the hydroxide may stick to the electrode surface and develop into a film as the process goes on (medhi, et al., 2008). in addition to coagulation, flocculation, and settling, electroflotation occurs during electrocoagulation [5]. 2.4 chemical reactions an electrocoagulation reactor comprises an electrolytic cell with a single anode and a single cathode in its basic form. the "sacrificial electrodes," which are conductive metal plates, may be made of the same material (anode and cathode). [5]. metallic cations are produced in the anode and hydrogen in the cathode [9]. while the cathode evolves hydrogen to enable pollutant removal by flotation. the small gas bubbles also encourage mixing [9] [7] [23][16] [3]. when water is electrolyzed, tiny oxygen bubbles that are created collide with air bubbles, causing the pollution particles to float [24] [16]. several methods exist for species interacting in a solution [3](kabdaşlı et al., 2012). first, switching to an electrode with the opposite charge (electrophoresis), followed by aggregation resulting from charge neutralization, the pollutant then forms a precipitate with the cation or hydroxyl ion oh-. bridge coagulation shahad fadhil al-khwarizmi engineering journal, vol. 20, no. 1, p.p. 1732(2024) 20 occurs when the metallic cation combines with oh to create a hydroxide with strong adsorption characteristics and bonds to the pollutant. these hydroxides sweep into the water and create bigger lattice-like structures, creating a sweep coagulation process pollution is then oxidized into less toxic particles. lastly, electro-flotation and adhesion removal [3] (kabdaşlı et al., 2012). the cationic monomeric species are created by the electrolytic dissolution of the al anode, as aluminum metal is used as the electrode. species like al+3 and al(oh)2 +. at acidic conditions. at appropriate ph values, they are transformed initially into al(oh)3 and finally polymerized to aln(oh)3n based on the following reactions. [27] al → al3+ (aq) + 3e al3+ (aq) + 3h2o → al(oh)3 + 3h+ (aq) nal(oh)3 → aln(oh)3n colloid particles are made less stable by producing monomeric and polymeric hydroxides. metal cations (mn+) destabilize colloidal particles, which encase colloidal particles in flocs that may be readily extracted from water through sedimentation or flotation. in equation 1, metal from the anode is oxidized to its cations (mn+) when the current is transmitted through the electrode. simultaneously, water is reduced to hydrogen gas, and the hydroxide ion (oh−) will be formed on the cathode (equation 2) (kabdaşlı et al., 2012) [14]. -en + n+m → m 2h2o(l) + 2e→ h2(g) + 2oh(aq) 3. factors affecting electrocoagulation there are many factors affecting the electrocoagulation process, such as electrical current applied (voltage applied), the distance between electrodes, the configuration of the electrode, ph of the solution, ions concentration at the start of the process, the materials used in the process as an anode and cathode, the type of treated water, the conductivity of the solution, temperature, hydrolysis time, sodium chloride concentration. 3.1 electrical current the electrical current is one of the most efficient components in the electrochemical precipitation and electrocoagulation processes [28]. increasing the electrode area and voltage and reducing the interelectrode distance are the three methods to enhance the current density [29]. according to faraday's rule, the mass created by an electrode is inversely related to the quantity of electricity utilized. the amount of adsorbent (aluminum hydroxide) produced is directly proportional to the current density and depends on time. [30] [31]. thus, as the adsorbent concentration rises, the amount of anode adsorption increases. this implies that adsorption depends on the anode's capacity to find binding sites [31]. knowing the current density that can impact the efficacy of electrocoagulation allows one to calculate the coagulant dosage rate, the rate at which hydrogen bubbles are produced, the floc size, and the pace at which flocs expand. the distance between the electrodes, the conductivity of the solution, and the current intensity employed during the electrocoagulation process are all considered when determining the voltage. the conductivity of the solution is inversely related to resistance. there is a suitable value for current density depending on the processing load [30]. also, higher current densities for electrocoagulation may be accomplished by expanding the electrode area, reducing the interelectrode distance, and raising the voltage since the voltage determines the current density (suryaningsih et al., 2021). the effectiveness of hardness reduction rises with an increase in electrical current. the size and growth rate of the created flocs increases at high voltages, impacting how well the process works for a ph value of 10 [32] [33]. increased electrical potential results in a rise in the quantity of oxidize aluminum and, as a result, increases the number of hydroxide flocs with high adsorption rates, which improves the effectiveness of hardness removal [34] [35]. the density of bubbles on apposition rises, but their size falls as the electrical current increases. the effectiveness of flotation rose as density, and bubble size decreased because larger bubbles' effective surface and retention time were lower than those of smaller ones [36]. naturally, surfactants are occasionally employed to reduce the surface tension of solutions and, as a result, the size of bubbles. because when the electrical current decreases, more time is needed to achieve equivalent efficiency. these facts are consistent with the findings of studies conducted in 2004 by ranta kumar et al. regarding the removal of arsenic by the electrocoagulation method and in 2007 by bzrafshan et al. regarding the effectiveness of the electrocoagulation method using aluminum electrodes in the removal of cr+6 [34] [35]. typically, 20 volts of electrical potential are needed to achieve noticeable efficiency. electrode electrical conductivity indeed has an impact on efficiency as well. the shahad fadhil al-khwarizmi engineering journal, vol. 20, no. 1, p.p. 1732(2024) 21 electrical conductivity is directly correlated with the electrode distance. as the electrode's distance increases, more power is used, which increases the removal's efficiency [37] [32]. 3.2 electrode types the choice of an electrode material depends on various elements, such as cost, low oxidation potential, compatibility with the system being utilized, etc. different electrodes were reported in the literature like carbon [38], mild steel (golder et al., 2005), iron [40], graphite titanium [41], titanium [42] and aluminum [43] according to reports, aluminum is quite effective and successful in removing pollutants under acceptable operating circumstances [16]. in the electrocoagulation reactor, while the direct current is delivered to them, untreated water flows between the anode and the cathode. electrodes are usually made of iron (fe) or aluminum (al) because they are inexpensive, readily available, harmless, and effective. the electrode configurations and materials are chosen depending on the wastewater pollution and the standard of the desired effluent. mostly iron is used to treat wastewater, while aluminum is used to treat drinking water [14]. the electrode material is widely recognized as a crucial element in electrocoagulation since it substantially impacts pollutant removal and energy consumption [14]. the electrode's chemical and physical characteristics impact the type of metal hydroxide and cations produced from the anode. additionally, the electrode material used for water and wastewater treatment must be safe for both the environment and individuals [44]. due to their multivalent ions' coagulation ability, aluminum and iron electrodes are commonly used in coagulation water treatment [45] [46]. 3.3 electrode configuration the electrocoagulation technique uses both monopolar and bipolar configurations. the anode and cathode are connected in parallel. in a parallel monopolar configuration, each couple of electrodes has a negative and positive charge. in a bipolar system, there is just one power connection and no electrical connection between the inner electrodes. iron and aluminum electrode efficiency is higher in the bipolar system. with a bipolar setup, organic matter may be reduced with an efficiency of 83%, while using a monopolar configuration, organic matter may be reduced by 71.1%. a flat electrode is less effective in removing pollutants than an electrode with holes (mesh). electrodes with this hole have 1.2 times more capacity to increase or release current than flat electrodes. [30] bipolar connections were shown to be more effective at removing organic compounds than monopolar connections when the efficacy of an electrocoagulation flotation method for water treatment was tested [47]. due to its larger surface area, the bipolar connection may have a higher operating cost [16][48]. it is well recognized that current density (cd) not only determines the dose rate of the coagulant, but also the flocs’ size, rate, and increment, all of which can affect how effectively the electrocoagulation works [49]. for the bipolar series system, as the current density grew, the removal of ions gradually increased for a certain amount of time before remaining mostly steady until the process was complete. therefore, anodic oxidation occurs more quickly in both systems when the current density is increased, which helps with the proper arrangement of amorphous aluminum hydroxide species inside the anode and within the bulk [16]. a greater surface area than that of monopolar parallel in the electrocoagulation system with bipolar series preferentially the anodic oxidation. due to the higher intensity of the bipolar connection compared to the other kind, the removal efficiency of the ions is similarly higher than that of the monopolar connection for the same amount of current density [50] (anwer & majeed, 2020). 3.4 initial ph it has been determined that ph is one of the key parameters influencing the effectiveness of the electrochemical process. as the process is mainly depends on the ph of the electrolyte at the start of the experiment. numerous studies found that removal efficiency declined at higher alkaline and acidic ph values. [52] and was ascribed to the amphoteric behavior of al(oh)3, which produces monomeric anions al(oh)-4 (at alkaline ph) and soluble al+3 cations (at acidic ph). these soluble species are known to be worthless for treating water. the aluminum generated at the anode formed polymeric species when the initial ph was neutral. (al13o4 (oh)24 7+) and precipitated al(oh)3, resulting in greater removal efficiency [53]. due to the increasing amount of iron dissolution, the turbidity removal efficiency for shahad fadhil al-khwarizmi engineering journal, vol. 20, no. 1, p.p. 1732(2024) 22 all retention durations was usually improved when the current density was raised. it should be noted that as the hydraulic retention periods investigated in one specific study were at least two orders of magnitude longer than the particle migration time, it is not believed to be a significant influence that the increased particle migration toward anodic surfaces brought on by the greater electrical field at a higher applied current [54]. in vasudevan research, at ph 12 (alkaline medium), the anionic phosphate in the solution would prefer to be repelled by the oxide surface due to its net negative charge, resulting in a minimum removal effectiveness of phosphate of 50%. however, ph 7 had the greatest quantity of phosphate removal [8], the same outcome, where the net negative charge of the oxide surface tends to repel the anionic nitrate in the medium [55]. because the influence of ph on coagulants depends on the reactions that are formed under various circumstances, the rate of hardness removal increases as ph increases. in neutral conditions: 3al(s) + 8h2o(l) → al(oh)2(s) + 2al(oh)3 + 4h2(g) in acid conditions 2al(s) + 6h2o(l) → o2 (g) + 4h2(g) + al(oh)2(s) in alkali conditions 2al(s) + 6h2o → 2al(oh)3(s) + 3h2o(l) in these equations, al(oh)3 and al(oh)2 settle while h2 gas moves upward and causes flotation. as reactions show, in acidity condition al(oh)2 and in alkali condition al(oh)3 are produced. since al(oh)3 settles more quickly due to its greater density and weight, its efficiency is also higher. as a result, it functions better when embedded in a precipitate [56] [57]. this outcome was consistent with ghernaout's 2008 study on the electrocoagulation technique for removing escherichia coli from surface water [57]. hence, according to the findings of this study and other investigations, the electrocoagulation process can serve as a ph moderator [32]; [35]. the contamination begins to settle at a particular ph. as the medium's ph rises or falls, the effectiveness of pollutant removal reduces. under some circumstances, the electrochemical al3+ polymerization and hydrolysis reaction may produce complex chemicals and polymers. at ph 4-9, using an al anode electrode will form al(oh)2+, al(oh)2 +, al2(oh)2 4+, al(oh)3, and al13(oh)32 7+. al(oh)4 is dominant at a medium of ph higher than 10, then the coagulant production process will regularly reduce [30]. 3.5 electrode distance the most essential factor in the electrocoagulation process is the effective electrode surface area and the inter-electrode distance [58]. the resistance between the electrodes would rise as their distance grew, necessitating more potential to overcome it. so, the cost of the process will be increased. however, the interaction between the ions and hydroxide polymers should ideally decrease as the distance between the electrodes increases. the voltage drop will rise as the inter-electrode distance rises at constant anode surface area and solution conductivity [59]. it can be seen that decreasing current density occurs when the distance between the electrodes is increased [29]. the highest pollutant removal effectiveness is attained by maintaining the ideal spacing between the electrodes. the effectiveness of pollutant removal is limited at short distances. this is because the strong electrostatic attraction causes the floc created by the metal hydroxide to deteriorate when it collides with another floc. due to a reduction in the electrostatic effect, which causes the generated ions to move more slowly as the distance between the electrodes increases, the effectiveness of pollutant removal increases. as a result, the metal hydroxide has more time to produce and agglomerate the floc, increasing pollutant removal effectiveness. additionally, it should be noted that energy consumption will be affected if the electrode gap widens [30]. khandegar discovered that the ions and species in the solution need more time to move between electrodes at greater electrode distances, which reduces electrostatic attraction and decreases the creation of flocs necessary to coagulate the desired species [60]. according to the equation that describes how electrical resistance varies, it is accurate to say that when electrode distance is increased, ion transport is obstructed, decreasing process efficiency and increasing energy consumption. in electrocoagulation, a thin layer (film) of metal hydroxide forms on the anode surface over time, increasing ohmic loss. as the inter-electrode distance increases, the problem gets worse. the applied potential must rise to maintain a consistent current density; as a result, there may be increased resistance, which would impede anode dissociation. it is undeniably true that lower anode oxidation and cation production shahad fadhil al-khwarizmi engineering journal, vol. 20, no. 1, p.p. 1732(2024) 23 result in lower removal efficiency [61]. the electrostatic attraction diminishes, which minimizes the formation of flocs required to coagulate the pollutant [46]. 3.6 sodium chloride from different previous researches, it is clear that increasing the chloride concentration increases the removal due to increased mass transport of chloride ions to the anode surface and increased diffusion in the diffusion layer of the anode. as a result, more amount of chlorine/ hypochlorite will be generated. hence the rate of removal was increased [62] [63]. another research shows that during the initial periods of electrolysis, the voltage increases sharply until a maximum value. after that, the voltage decreases to reach a pseudo-stationary value. moreover, the maximum voltage value and the duration time required to achieve the pseudostationary plateau are much higher with lower nacl concentrations. as nacl dose increases, the cell voltage decreases rapidly. in one of the studies, one can observe that the amount of aluminum generated increases rapidly as the nacl dose rises. subsequently, the quantity of al3+ (coagulant) produced becomes almost constant [64]. it is observed that the amount of aluminum generated increases rapidly as the nacl dose varies from 0 to 15 ppm. however, the quantity of al+3 (coagulant) produced beyond this concentration becomes almost constant. this indicates that increasing the nacl concentration up to a certain point enhances the generation of al+3. in addition, increasing the chloride concentration in the electrocoagulation process positively impacts the removal of pollutants. the higher chloride concentration facilitates the mass transport of chloride ions to the anode surface and increases diffusion in the diffusion layer of the anode. consequently, more chlorine/ hypochorite will be produced, resulting in accelerated rate removal[64]. 3.7 initial concentration in an electrocoagulation process, the initial concentration factor refers to the concentration of the target substance or contaminants in the wastewater or solution at the start of the treatment. it plays a significant role in determining the effectiveness and efficiency of the electrocoagulation process in several ways. it is important to note that the specific relationship between the initial concentration factor and the electrocoagulation process can vary depending on the nature of the contaminants, the electrode material, and the process conditions. furthermore, a higher initial concentration of the contaminant leads to an elevation in electrical conductivity resulting in a reduction of metal ion (iron and aluminum) released from the electrode surface. this occurs because it prompts the formation of a passive layer on the electrode surface and increases impedance modulus within the system [65]. when maintaining a constant voltage, a nearly fixed quantity of ions is released by creating metal hydroxide complexes and flocculants as coagulants. consequently, as the concentration of contaminants rises, the quantity of coagulant rises; this quantity becomes inadequate for effective sedimentation. additionally, an increase in the initial concentration of contaminants results in highlighted oxidation reactions at the electrode surface, decreasing the anode electrode’s efficacy in releasing metal ions and generating hydroxyl radicals [66][67]. 3.8 operating temperature when the temperature is too high, the large pores of the al(oh)3 gel shrink, resulting in more compact flocs that are more likely to deposit on the surface of the electrode. higher temperature gives a higher conductivity hence lower energy consumption[24]. numerous researchers have investigated the influence of solution temperature on the performance of the electrocoagulation reaction, as the temperature of the solution is a fundamental parameter that affects process efficiency[68]. previous work findings indicate that the elimination of phosphate ions is enhanced as the solution temperature rises to 60°c. however, byond this temperature, the removal efficiency of phosphate ions decreases. raising the solution temperature can improve the transfer of ions from the anode or cathode surface to the solution bulk. this improvement is attributed to reduced solution viscosity and increased ion diffusivity. the reduction in the efficiency of phosphate removal observed at solution temperatures exceeding 60°c can be attributed to the increased passivation of the metal anode and cathode. this passivation occurs due to the formation of protective metal oxide layers, which leads to decreased mn+ ions and ultimately impacts the performance of the electrocoagulation reactor. furthermore, it has shahad fadhil al-khwarizmi engineering journal, vol. 20, no. 1, p.p. 1732(2024) 24 been noted that higher temperatures can cause the contraction of larger pores within the metal hydroxide gel, resulting in the formation of dense flocs that are more prone to depositing on the electrode surface. additionally, increasing the temperature enhances the solubility of aluminum. however, the effect of temperature on removal efficiency can vary depending on the specific mechanism involved in pollutant removal [69]. according to vasudevan study, the amount of cadmium removal by the absorption increased with increasing temperature [70]. 3.9 time the duration of the electrolytic process has an impact on the efficiency of the treatment. the electrode dissolution at the anode during electrolysis results in the generation of coagulating species. in one of the studies, the effectiveness of the dye removal is directly related to the concentration of metal ions produced on the electrodes. as the electrolysis period is extended, the concentration of metal ions and their hydroxide flocs also increases [71]. another research finding was, during the treatment of leachate using the electrocoagulation (ec) process, it was observed that increasing the electrolysis time improved turbidity removal [72]. energy and electrode consumption also tend to increase as the reaction time increases in the electrochemical process. this highlights the significance of reaction time as a crucial parameter that impacts the cost-effectiveness of the electrocoagulation process in treating polluted waters[73]. the treatment efficiency of the electrochemical process is also influenced by the reaction time. the duration of electrolysis time (t) plays a crucial role in determining the rate at which fe+2 or fe+3 ions are produced from the iron electrode [74]. there are a lot of studies regarding ec, table 1 shows some of the latest researchs, in this table different factors were studied. some of the main factors will be summarized below: table 1, survey for previous researchs reference treated water removal electrodes factors [75] village water in serilanka 83% hardness al time 99% floride current density [76] ground water 98.60% arsenic al the precence of phosphate, silicate, biocarbonate , flouride, boron time [77] wastewater 84% bod al ph 96% p time 99% fc packed density 80.00% cod current [78] simulated contains calicium , turbidity 36% calicium al initial calicium conc. initial turbidity 93.50% turbidity time current density [79] well in weld county, and well in oklahoma 97.30% turbidity al electrode material 34.80% cod initial ph 47.80% bod applied current 87.80% turbidity fe contact time 37.40% cod no. of electrodes 54% doc [80] a secondary treated wastewater from doha plant 88.30% total phosphorous al symmetric and unsymmetric electrodes ac, dc current 82.40% cod time current density [81] chlorella vulgaris suspension 88% (fe) chlorella vulgaris anode: fe/al cathode: stainless steel 73% (al) chlorella vulgaris shahad fadhil al-khwarizmi engineering journal, vol. 20, no. 1, p.p. 1732(2024) 25 [63] simulated wastewater 98% dye al ph initial concentration nacl concentration 90% cod voltage ec versus cc current density [82] ground water / vienna, untreated water from lake in ohio 100% perfluorooctan oic acid al reversed polarity 100% microcystins voltage ph [83] by product produced by oil gas industry 99% tss al current density 100% oil&grease 89.7% removal of tss with steel slag containing system compared with conventional system without steel slag 55.7%removal residance time steel slag concentration [84] municipal wastewater 100% tp(total phosphorus) graphite/catho de, al,fe/anode bipolar electrode on ec 80% tn (total nitrogen) bipolar electrode on pollutant removal >90% toc >90% turbidity [85] pb-zn flotation wastewater 37.70% cod/al mixedwater al/fe different wastewater types pyrite concentrate wastewater 62.70% cod/fe mixed water current density pyrite tailing wastewater 25.70% cod/gac mixed water delectrode type mixed wastewater 77.62% cod/ec mixed water ph >80% cod/(ec,ga c) mixed water time 80.24% ec/pb-zn flotation addition of na2so4 79.33% ec/pyrite concentrate comparing ec with gac 85.05% ec/pyrite tailing pb/zn grade recovery 82.84% ec/mixed [86] oily saline wastewater from drilling oil sites 17.50% tds al current density 83.22% tss time 60.38% hco3 22% cl 25% ca [87] texile wastewater 96 dfz436 fe initial ph 76 cod current density 90 dfz437 al time 68 cod 93% cod nf270 membrane 99% conductivity 97% chloride 91% tds [29] river water, iron water, hard water > 99% fe al current 90% turbidity time 80.72% kmno4 distance between electrodes shahad fadhil al-khwarizmi engineering journal, vol. 20, no. 1, p.p. 1732(2024) 26 [88] al-kut textile wastewater 96.40% turbidity al/ ec ph turbidity 75.40% turbidity chemical coagulation conductivity tds [51] synthetic blowdown water of cooling tower 60% calicium al current density 97% magnesium initial ph 98% silica time 15-60 min. [89] model and actual surface waters tthm ironec/cc formation percentage during the ec and cc nom doc [90] raw water(with high turbidity) 84% color al 86.44% turbidity [91] groundwater taken jaffna 85% hardness iron mp,bp compared voltage surface area to volume ratio initial ph time [59] sawa lake, almuthanna, iraq 91% tds al current density temperature 93% cl time 15-60 min. 92% br ph inter electrode distance 90% so4 stirring speed [92] bore well water 89.45% hardness al ph 83.43% alkalinity current density 74.07% tds time voltage 4. conclusion use of electrocoagulation for water treatment has been studied for treating drinking water and waste water rectifying. regarding the efficiency of the process the most important factors that affecting the electrocoagulation process (ec) are electrode configuration, current density, process time, initial pollutant concentration, the ph and the presence of competing ions. many studies show that a lot of particles and ions were removed successfully by electrocoagulation such as iron, boron, sulfate, nitrate, hardness, turbidity, silica, viruses, bacteria. it has been noticed that different removal efficiency of different species was varied according to factors mentioned in this article. i.e for the same water sample used the efficiency of removal varied depending on the electrode material type, conductivity of solution, ph of sample, current /voltage applied, distance between electrodes and electrode configuration. abbreviation bod biochemical oxygen demand cod chemical oxygen demand p phosphorous fc fecal coliforms toc total organic carbon gac granular activated carbon tds total dissolved solid tss total suspend solid dfz436 color value (durchsichts =indexes of transparency) references [1] c. sarala, “domestic wastewater treatment by electrocoagulation with fe-fe electrodes,” international journal of engineering trends and technology, 2012. 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(2024) 17-32، صفحة 1العدد ،20المجلد جلة الخوارزمي الهندسيةم شهد فاضل 32 مراجعة: العوامل المؤثرة على عملية التخثر الكهربائي النواع المياه المختلفة ***أيمن هادي العالق **نصير عبود عيسى الحبوبي *شهد فاضل عبد الربيعي جامعة النهرين / العراق / **،* قسم الهندسة الكيمياوية/ كلية الهندسة ***جامعة دومينيون/ الواليات المتحدة االمريكية shahad.fadhilma@gmail.com :* البريد االلكتروني naseer.a.alhaboubi@nahrainuniv.edu.iq :االلكتروني** البريد alal005@odu.edua: *** البريد االلكتروني الخالصة يجب ان تحتوي على متطلبات فيزيائية وكيميائية وبيولوجية معينة. هناك العديد من الطرق والتقنيات من اجل استعمال المياه الخام كمصدر للشرب ، وانها طريقة فعالة ومتطورة لمعالجة العديد من الملوثات طريقة التخثر الكهربائي. ،باالضافة للطرق التي تستخدم المواد الكيمياوية ،المتوفرة لمعالجة المياه باالضافة للعسرة والعكارة والمواد الصلبة العالقة والمواد العضوية وغير العضوية ،البكتريا والفيروسات والحديد والفلوايد والكبريتات والبورونبما في ذلك ذه المقالة على بشكل متكرر في معالجة العديد من أنواع المياه ومياه الصرف الصحي. تركز ه التخثر الكهربائي ، واللون. يتم استخدام bod، و codو ة متنوعة من الملوثات. التطورات الحالية في التخثير الكهربي لمعالجة المياه وتاثيرات ظروف التشغيل المختلفة. نظًرا لفعاليتها غير العادية في إزالة مجموع تقدم هذه المقالة تحليالً شامالً لألدبيات المعاصرة التي تلتزم فقد اجتذبت الكثير من االهتمام مؤخًرا وذلك لقابليتها االستثنائية في معالجة العديد من الملوثات. المتغيرات األساسية باستخدام التخثير الكهربي في مجموعة متنوعة من طرق معالجة المياه، مع التركيز على المتغيرات المختلفة التي تؤثر على أداء العملية. التركيز وطريقة ربط االقطاب، ودرجة الحموضة ،المسافة بين األقطاب، تركيز كلوريد الصوديوم، مادة المستخدمة القطب، هي التيار الكهربائي، للمقالة درجة الحرارة والزمن. االولي للملوثات او االيونات، mailto:shahad.fadhilma@gmail.com mailto:naseer.a.alhaboubi@nahrainuniv.edu.iq mailto:aalal005@odu.edu this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 19, no. 4, december, (2023) p. p. 115 preparation, characterization, and tetracycline adsorption efficiency of tea residue-derived activated carbon hala a. faisal* alaa kareem mohammed** nadya hussin al sbani*** wan nor roslam wan isaha**** *,** department of biochemical engineering / al-khwarizmi college of engineering/ university of baghdad/ iraq ***department of chemical engineering/ faculty of oil and gas engineering/ al zawia university/ libya ****department of chemical and process engineering/ faculty of engineering and built environment/ universiti kebangsaan malaysia/ selangor/ malaysia corresponding author *email: halaali123454@gmail.com **email: dr.alaa@kecbu.uobaghdad.edu.iq ***email: n.asbani@zu.edu.ly ****email: wannorroslam@ukm.edu.my (2023 september 13 accepted; 2023 july 20 received) https://doi.org/10.22153/kej.2023.09.001 abstract the process for preparing activated carbon (ac) made from tea residue was described in this paper. investigated were the physicochemical characteristics and adsorption efficiency of the produced ac. activation with potassium hydroxide (koh) and carbonization at 350 °c are the two key steps in the manufacturing of ac. the activated carbon was used to adsorb tetracycline (tc). different parameters were studied at room temperature to show their effects on the adsorption efficiency of tc. these parameters are the initial concentration of adsorbate tc, solution acidity ph, time of adsorption, and adsorbent dosage. the prepared active carbon was characterized using fourier transform infrared spectroscopy (ftir), scanning electron microscopy (sem), x-ray diffraction (xrd), and brunauer-emmett-teller (bet). the equilibrium of tc adsorption on the tea-activated carbon tac is effectively represented by the langmuir model. tetracycline could be adsorbed onto the prepared activated carbon with a maximum capacity of 45.662 mg g-1. adsorption kinetics are well represented by pseudo-second-order. the investigation of adsorption thermodynamics demonstrates that tc adsorption on tac is endothermic and spontaneous. keywords: tea residue, activated carbon, tetracycline, central composite design. 1. introduction the ecosystem of the earth is currently being continuously contaminated by various pollutants. pharmaceuticals are released. into water systems in large amounts through a variety of human activities, such as waste streams from hospitals and the pharmaceutical and veterinary sectors, which are one major cause of water contamination [1]. these chemicals can infiltrate aquatic bodies, including surface and groundwater [2], [3]. pharmaceutical effluents containing antibiotics have recently received a lot of attention due to the increased use of antibiotics [4]. since antibiotic resistance genes can be induced by prolonged exposure to relatively low quantities of antibiotics, the use of antibiotics rose quickly, raising concerns about their residues in the environment [5]. tetracycline (tc) is a broad-spectrum antibiotic that has become one of the most commonly used antibiotics in the world due to its low cost, good quality, and useful antibacterial qualities [6]. it was mailto:dr.alaa@kecbu.uobaghdad.edu.iq mailto:n.asbani@zu.edu.ly mailto:wannorroslam@ukm.edu.my https://doi.org/10.22153/kej.2023.09.001 hala a. faisal al-khwarizmi engineering journal, vol. 19, no. 4, p.p. 115 (2023) 2 found in the 1940s and began to be utilized as a therapeutic agent to protect human health in the 1950s [7]. it has been extensively used in agriculture to prevent the pharmacological efficacy of infectious diseases and as a growth stimulant for microorganisms. because tetracycline (tc) does not quickly biodegrade, it poses a serious risk to both people and the environment [8]. consequently, it is essential to remove tc residues from effluents before releasing them into the environment [7], [9]. the removal of tc from wastewater has been studied using a variety of methods, including biological treatment, coagulation, sedimentation, ozonation, photocatalysis, electrochemical degradation, and adsorption [10]. adsorption technologies have been extensively used to remove pharmaceuticals from surface water and municipal wastewater compared to other water treatment methods because they can provide several advantages, such as simple design, simple operation, and high adsorption effectiveness [11]. several materials have been studied as adsorbents for the adsorption of tc, such as resin, silica, clay, multi-walled carbon nanotubes, zeolite, graphene oxide, chitosan, and activated carbon [12]. activated carbon is a powerful adsorbent because of its surface's numerous functional groups, porosity, and huge surface area. it also has a well-developed interior structure. it has been widely utilized to remove numerous organic and inorganic pollutants from contaminated streams that are biologically resistant [13], [14]. commercial activated carbon is one of the most commonly used industrial adsorbents for separation, purification, and recovery procedures. however, it requires regeneration after each adsorption operation and has a high production cost. utilizing biomass waste as a precursor to ac, such as groundnut husks, sugarcane bagasse, coconut shells, bamboo, rice husks, mango kernels, and tea residue, is a potential method for lowering the overall cost associated with its manufacturing [15], [16]. the two fundamental phases in the preparation of acs are carbonization and activation. the goal of carbonization is to reduce the number of volatiles in the starting material. this is done by pyrolyzing the precursor at temperatures between 400 and 850 °c, which breaks it down into gases and tars made up mostly of hydrogen, oxygen, and nitrogen. the char created using this process will have a high fixed carbon content but little surface area and porosity. therefore, an activation step is necessary to increase porosity and organize the structure, resulting in the extremely porous solid known as ac [17], [18]. there are two ways to make activated carbon: physical activation and chemical activation. in the physical activation method, the raw material is carbonized at a high temperature and then activated with steam or carbon dioxide. in the chemical activation method, the precursor is soaked in chemicals like h3po4, naoh, k2co3, koh, zncl2, etc. before being carbonized in an inert atmosphere [19]. in this study, tea residue was selected as a precursor to prepare activated carbon using chemical activation with koh. the activated carbon was investigated as an adsorbent to adsorb tetracycline from polluted water. 2. materials and methods 2.1 materials the tea residue was collected locally from leftover tea used in homes. tetracycline (tc) was chosen as the target adsorbate, supplied by the state enterprise for drug industries and medical appliances, samara, iraq. tetracycline was directly used without any further treatment. potassium hydroxide (koh), used as the activating agent with a minimum assay of 85%, was purchased from himedia, india. 2.2 preparation of activated carbon the waste tea was boiled with distilled water for 0.5 h to remove water-soluble materials, then washed with distilled water until the washing water was colorless, and then dried at 110 °c in an air oven for 10 h with flipping. after pretreatment, the raw material was placed in a steel or porcelain crucible for carbonization in a furnace at 350 °c for 30 min under a flow of n2 (150 cm3/min). next, the product is allowed to cool inside the furnace, with the nitrogen gas still flowing, until the temperature reaches 100 c. the carbonized product was then withdrawn from the furnace and allowed to cool to room temperature. then, it was mixed with 30% koh at a weight ratio of 2:3 (koh: carbonized material) and mixed for 30 min using a shaker at 140 rpm. the sample was then filtered from the base residue. to prepare the activated carbon in its final step, the product was put in a closed crucible in a muffle furnace at 900 c for 1 h under a flow of n2 (150 cm3/min) [16]. the product is then allowed to cool to room temperature. warm distilled water was used to thoroughly wash the obtained activated carbon (ac) until the solution's ph reached 7. the ac samples were dried overnight at 110 °c. the product was crushed with a mortar and pestle and hala a. faisal al-khwarizmi engineering journal, vol. 19, no. 4, p.p. 115 (2023) 3 then sieved to get a 350 μm or smaller particle size. finally, the product was preserved in a desiccator for the upcoming batch trials. 2.3 activated carbon characteristics to characterize the manufactured adsorbent, various characterizations were done. the surface morphologies were examined using scanning electron microscopy (sem). the crystalline phase was identified using x-ray diffraction (xrd). edx was used to analyze the absorbent's elemental composition. the above analysis was carried out locally at al-khoura co. using kbr pellets in the range of 4000-400 cm-1. fourier transform infrared spectroscopy (ftir 8400s shimadzu) was employed to look into the functional groups on the adsorbent surface. the analysis was carried out at the al-nahrain university / college of biotechnology department. the surface area and porous structure were determined using the brunauer-emmett-teller (bet) formula. the analysis was carried out at the petroleum research and development centre (prdc). 2.4 adsorption study batch adsorption studies were carried out at room temperature using 25 ml of tetracycline tc solution at different initial concentrations (30–150 mg/l), ph (2–11), time (20-300 min), and active carbon (ac) dosage (0.05–0.5 g/25 ml) at a constant speed of agitation (140 rpm). 25 ml of tc solution of the specified initial concentration was put in the erlenmeyer flask (100 ml), and then a known amount of the ac was added to the solution. the mixture was shaken in an orbital shaker (edmund buhler sm25, german) at 140 revolutions per minute. after that, filter paper (whatman) was used to remove the adsorbent from the aqueous solution. a double-beam uv-visible spectrophotometer (pg instruments, model uv t80, england) was used to evaluate the tc's final concentration. the tc has a wavelength of 276 nm. the proportion of tc removed by the prepared activated carbon (ac) was calculated using eq. (1)[20]. 𝑅 % = [ 𝐶₀ − 𝐶𝑒 𝐶₀ ] ∗ 100% … (1) where r represents the removal percentage, 𝐶𝑜 & 𝐶𝑒 are the initial and equilibrium concentrations of tc (mg/l) respectively. the equilibrium adsorption capacity of active carbon for tetracycline, qₑ (mg/g), was calculated using eq. (2) [21], [22]. 𝑞ₑ = (𝐶₀ − 𝐶𝑒)𝑉 𝑚 … (2) where qₑ is (tc) adsorbed amount (mg/g); v is the volume of the sample (ml) and m is the quantity of the adsorbent added (g). 2.5 adsorption experimental design four variables at five levels were experimentally designed using central composite design (ccd). these variables were: tc initial concentration co, solution acidity ph, adsorption time t, and adsorbent dosage. the selection of the variable value ranges was informed by prior research conducted on the application of activated carbon to eliminate specific pharmacological pollutants. these variables were studied to investigate their impact on the adsorption efficiency of tc. experimental design software was used to design, analyze, and optimize the affecting factors, as well as obtain an empirical model representing the adsorption efficiency of the tc. table 1 presents the independent factors with their coding and actual levels selected for process optimization. hala a. faisal al-khwarizmi engineering journal, vol. 19, no. 4, p.p. 115 (2023) 4 table 1, adsorption experimental design following ccd run a: adsorption time (min) b: ph c: dosage (g/25ml) d:sa initial conc. (mg/l) r% (experimental) r% predicted residuals 1 230 4 0.39 60 85 80.68 4.32 2 90 9 0.16 120 67 69.51 -2.51 3 160 7 0.28 150 55 54.21 0.7917 4 160 7 0.05 90 62 62.99 -0.9861 5 90 9 0.39 60 65 66.35 -1.35 6 230 9 0.16 120 65 67.11 -2.11 7 90 4 0.39 120 55.333 55.24 0.0971 8 230 4 0.16 60 56 59.44 -3.44 9 230 4 0.16 120 45 41.85 3.15 10 160 7 0.28 90 77 77.67 -0.6667 11 20 7 0.28 90 54 55.71 -1.71 12 160 11 0.28 90 76 72.49 3.51 13 230 9 0.39 120 67 68.35 -1.35 14 230 4 0.39 120 52 54.17 -2.17 15 160 7 0.28 30 75 75.82 -0.8195 16 90 9 0.16 60 65 64.61 0.3889 17 230 9 0.16 60 90 88.29 1.71 18 90 4 0.16 60 46 42.85 3.15 19 90 4 0.39 60 56 55.67 0.3334 20 160 7 0.50 90 78 77.04 0.9584 21 160 7 0.28 90 78 77.67 0.3333 22 230 9 0.39 60 95 98.44 -3.44 23 90 9 0.39 120 64 62.33 1.67 24 160 2 0.28 90 33 36.54 -3.54 25 90 4 0.16 120 53 51.33 1.67 26 160 7 0.28 90 78 77.67 0.3333 27 300 7 0.28 90 80 78.32 1.68 the effects of the parameter on tc sorption were modeled and designed using the ccd method, as illustrated in table 1. the adsorption time (a), ph (b), adsorbent dosage (c), and initial concentration of tc (d) were used to optimize the response removal. of tc (r%). the value of the coefficient of determination r2 was used to assess the fit of the regression, eq. (1), and it was found to be 0.9778, approving the model's accuracy. 𝑅% = −120.66 + 0.39 a + 21.26 b + 202.22c + 1.21 d + 0.011 ab + 0.27 ac − 0.003 ad − 10.95 bc − 0.013 bd − 0.66 cd − 0.00054 a2 − 1.143 b2 − 151.166 𝐶2 − 0.0035 d2 … (1) figure 1 plots the predicted vs. observed values of removal percent content in the five-factor ccd analysis. the predicted responses from the empirical function are almost identical to the measured values, where all points are close to the line in the range of the operating factors. hala a. faisal al-khwarizmi engineering journal, vol. 19, no. 4, p.p. 115 (2023) 5 fig. 1. predicted vs. actual values of the percentage removal of tetracycline adsorption. 3. results and discussion 3.1 characterization of the activated carbon 3.1.1 characterization using ft-ir figure 2 displays the ftir spectra of both the raw material, tea residue, and the tac. the o-h stretching vibration of the hydroxyl group is responsible for the bandwidth at 3415.99 cm-1. the peak at 2898.9 cm-1 results from the c-h stretching of the benzene ring. the presence of a methoxy group band in the precursor is responsible for the broadband at 2850.54 cm-1. the bands at 1727.74 cm-1 and 1639.24 cm-1 are due to the chemical formula c = o for carboxymethyl cellulose [23]. the low absorption at 1524.37 cm1 is due to the oscillation of the aromatic skeletal structure. the peak at 1458.07 cm-1 represents the carboxylic groups [24]. the bands between 1000 and 1300 cm-1 are produced by the c-c and c-o vibrations of alcohols, phenols, and ethers. the band at 588.86 cm-1 is caused by the si-o-si vibration [25]. the peaks in activated carbons associated with the o-h, ch3o, c-h, c=o, c-c, and c-o groups decreased or vanished after koh activation [22]. fig. 2. ftir spectra of the raw material, tea residue, and tea active carbon tac. 3.1.2 characterization using sem the sem examination was conducted to investigate surface morphology and the shape of the active carbon (tac), as shown in (figure 3a). the micro-surface morphologies of tac are depicted in figure 3. the internal structure of the activated carbon depressions has several etched pores and channels, in addition to a random distribution of depressions of different sizes. this turned out to agree with recent reports [16] that studied the removal of o-cresol by activated carbon derived from waste tea. eds analysis was used to evaluate the adsorbent's elemental composition. according to this observation, the primary components of tac were c (76.7%), o (14%), mg (0.9%), al (0.4%), and ca (5.9%) (figure 3b). 0 20 40 60 80 100 0 10 20 30 40 50 60 70 80 90 100 p re d ic te d v al u e actual value 5 8 8 .6 8 1 0 2 2 .5 9 1 1 4 6 .7 9 1 2 3 0 .5 31 4 5 8 .0 71 5 2 4 .3 7 1 6 3 9 .2 4 1 7 2 7 .7 4 2 8 5 0 .5 4 2 8 9 8 .9 9 3 4 1 5 .9 9 40080012001600200024002800320036004000 t % wavelegth, cm-1 tac hala a. faisal al-khwarizmi engineering journal, vol. 19, no. 4, p.p. 115 (2023) 6 fig. 3. (a) sem image of active carbon, (b) eds. 3.1.3 surface area and pore structure brunauer-emmett-teller (bet) characterization showed that the activated carbon made from tea residue (tac) had a specific surface area of 747 m2/g and an average pore volume of 0.477 m3/g. 3.1.4 characterization using xrd powder xrd analysis was used to describe the crystallinity of the tac surface. the tac sample's xrd spectrum is displayed in figure 4. these spectra showed weak peaks at 22° and 44°. these peaks demonstrate the presence of a graphite crystal structure in tac. this turned out to be consistent with recent reports [26]. fig. 4. x-ray diffraction patterns of tea residue activated carbon tac. 3.2 anova analysis the analysis of variance displayed in table 2 records the actual results of anova evaluations. the significance of a parameter was indicated by its p-value. the model’s f-value of 37.69 and pvalue of 0.0001 imply the model is significant. in this case, a, b, c, d, ab, ad, bc, cd, a², b², c², and d² are significant model terms. values greater than 0.05 indicate the model terms are not hala a. faisal al-khwarizmi engineering journal, vol. 19, no. 4, p.p. 115 (2023) 7 significant. the analysis results in table 2 indicate the significant effect of each variable in the model on the removal efficiency. it can be observed that the ph parameter in the linear form b (f-value = 186.64) has the most significant effect on removal efficiency, followed by the linear term of the mixing time a (f-value = 73.86). in interactive terms, the most significant effective parameters are mixing time and initial concentration ad (f-value = 65.52), and the other is the ph and tac dosage bc (f-value = 11.83). table 2, anova results of tetracycline adsorption findings the non-significant factors in eq. (1) are eliminated, and only the significant factors are included in eq. (2). 𝑅% = −120.66 + 0.39 a + 21.26 b + 202.22c + 1.21 d + 0.011 ab − 0.003 ad − 10.95 bc − 0.66 cd − 0.00054 a2 − 1.143 b2 − 151.166 𝐶2 − 0.0035 d2 … (2) an analysis of variance was used to assess the suitability of the model. the quadratic model was found to be very significant, with the values of rsquared, adjusted r-squared, and predicted rsquared correlation coefficients equal to 0.9778, 0.9518, and 0.8723, respectively. this value indicates the proportionality of the experimental values and the predicted adsorption removal values. the anova analysis of tetracycline adsorption nearly agrees with that of [27], which studied the adsorption of tetracycline onto ac and analyzed the results using rsm. 3.3 adsorption parameters interactions 3.3.1 interaction between adsorption time and initial concentration of tc figure 5 shows the 3d response surface and contours of how the most important factors, adsorption time and initial concentration of tc, interact at ph =9. the p-value and f-value are indicators of these outcomes, as shown in table 2. figure 5 shows that the adsorption time is the most important factor in the absorption process. when the initial concentration of tetracycline (co) was between 30 and 90 ppm, increasing the adsorption time led to a higher percentage of tetracycline being removed. when the concentration of tetracycline is greater than 100 ppm, the adsorption capacity gradually slows down over time. this observation is because increasing concentrations require more time to be adsorbed. this behavior is in agreement with [28]. the optimum values for mixing time and initial concentrations are 230 min and 60 ppm, respectively. source sum of squares mean square f-value p-value model 5478.72 391.34 37.69 < 0.0001 significant a-time 766.9 766.9 73.86 < 0.0001 significant b-ph 1938.01 1938.01 186.64 < 0.0001 significant c-dosage 296.34 296.34 28.54 0.0002 significant d-co 700.56 700.56 67.47 < 0.0001 significant ab 50.17 50.17 4.83 0.0483 significant ac 70.84 70.84 6.82 0.0227 ad 680.34 680.34 65.52 < 0.0001 significant bc 122.84 122.84 11.83 0.0049 significant bd 12.84 12.84 1.24 0.2879 cd 79.51 79.51 7.66 0.0171 significant a² 151.31 151.31 14.57 0.0025 significant b² 714.74 714.74 68.83 < 0.0001 significant c² 78.09 78.09 7.52 0.0179 significant d² 213.46 213.46 20.56 0.0007 significant residual 124.6 10.38 pure error 0.6667 0.3333 cor total 5603.32 hala a. faisal al-khwarizmi engineering journal, vol. 19, no. 4, p.p. 115 (2023) 8 fig. 5. counter plots and 3d of removal percent (%) of tc as a function of time (min) and initial concentration of tc (ppm). 3.3.2 interaction between ph and tac dosage the solution ph is an important factor that can greatly affect the adsorption process because it changes the adsorbent’s surface charge and ionization behavior. figure 6 shows the 3d response surface and contours of how ph and the amount of active carbon affect the adsorption of tetracycline. these are the two most important factors. figure 6 shows that the adsorption percentage increased with increasing ph. this can be due to the competition for adsorption sites between tetracycline and h+ that occurs on the surface of the adsorbent at a low ph. with increasing ph, the adsorbent gradually gains more adsorption capacity and reaches its maximum adsorption of 97% at ph 9 and an ac dose of 0.39 g per 25 ml solution. however, with ph = 11, the adsorption capacity of tac fibers tends to decrease slightly because of the attenuation of hydrogen bonding due to the generation of oh-1. this behavior is in agreement with [28]. fig. 6. counter plots and 3d of removal percent (%) of tc as a function of ph and tac dosage (g/25ml). hala a. faisal al-khwarizmi engineering journal, vol. 19, no. 4, p.p. 115 (2023) 9 3.4 optimization of process variable the model accuracy was validated by optimizing the process parameters of the adsorption of tetracycline on tac. the obtained experimental result confirmed the validity of the model, as shown in table 3, with 85% removal. table 3, adsorption of tetracycline on tac optimization following the designed model. process parameters (coded) a b c d predicted r2 actual r2 error % best values 230 9 0.39 60 0.8723 0.9518 0.08 4. adsorption isotherms the equilibrium data is used to calculate the adsorption isotherms, which are the basic requirements for designing adsorption systems. the sorption data for tetracycline is fitted with two linearized forms of isotherm models (langmuir and freundlich), as shown in figure 7. accordingly, the empirical coefficients in table 4 for each model were determined from the slope and intercept of the linear plot. eq. (3) represents the mathematical expression of the langmuir isotherm [29]. 𝑞𝑒 = 𝐾𝐿 𝑞𝑚 𝐶𝑒 1 + 𝐾𝐿𝐶𝑒 … (3) the linearized form of eq. (3) is given by eq. (4) 1 𝑞𝑒 = 1 𝑞𝑚 + 1 𝑞𝑚𝐾𝐿 1 𝐶𝑒 … (4) where 𝑞𝑒: amount of tetracycline adsorbed per unit mass of ac at equilibrium (mg/g). 𝑞𝑚 : maximum capacity of adsorption (mg/g). 𝐾𝐿 : constant in langmuir isotherm (l/mg). 𝐶𝑒 : the equilibrium concentration of the tetracycline in the solution at equilibrium (mg/l). the values of both 𝐾𝐿 and 𝑞𝑚 can be calculated using adsorption experimental data and eq. (4). the isotherm model of freundlich is based on the assumption of heterogeneous surface energies and multi-layer adsorption. the freundlich isotherm is given by eq. (5) [21]. 𝑞𝑒 = 𝐾𝐹𝐶𝑒 1 𝑛 … (5) eq. (6) represents the linearization form of the freundlich model ln(𝑞𝑒) = ln(𝐾𝐹) + 1 𝑛 ln(𝐶𝑒) … (6) the constant parameters of the freundlich isotherm (𝐾𝐹 and 𝑛) represent the adsorption capacity and the adsorption intensity, respectively. these values can be predicted from the experimental data using eq. (6). the fitting of experimental data according to langmuir and freundlich isotherm models is shown in figure 7. fig. 7. linear form of the isotherm models for sorption of tetracycline onto tac, (a) freundlich, (b) langmuir. y = 0.3473x + 0.0219 r² = 0.9936 0 0.02 0.04 0.06 0.08 0.1 0.12 0 0.05 0.1 0.15 0.2 0.25 1 /q e 1/ce langmuir model y = 0.497x + 1.6755 r² = 0.9692 1.5 2 2.5 3 3.5 4 1 2 3 4 5 l n q e lnce freundlich model a b hala a. faisal al-khwarizmi engineering journal, vol. 19, no. 4, p.p. 115 (2023) 10 the values of langmuir isotherm parameters (qm, kl) and freundlich isotherm (n, kf) as well as the correlation coefficient (𝑅2) are listed in table 4. table 4, parameters of langmuir and freundlich equations. from the values of the correlation coefficients (𝑅2), it is concluded that the langmuir model fits the experimental data better than the freundlich model, which suggests a high monomolecular layer on the surface of the tac. 4.2 adsorption kinetics to understand the controlling mechanism and the adsorption rate, the adsorption kinetics of tetracycline onto tac were studied using two kinetic models: pseudo-first-order and pseudosecond-order. eqs. (7) and (8) represent the nonlinear forms of pseudo-first-order and pseudosecond-order kinetics, respectively [29], [30]. ( 𝑑𝑞𝑡 𝑑𝑡 ) = 𝐾1 (𝑞𝑒 − 𝑞𝑡) … (7) 𝑑𝑞𝑡 𝑑𝑡 = 𝐾2(𝑞𝑒 − 𝑞𝑡)2 … (8) the parameters 𝑞𝑡 and 𝑞𝑒 (mg/g) represent the amounts of the tc that were adsorbed on the tac at any time (t) and equilibrium, respectively. the parameters 𝐾1(min-1) and 𝐾2(𝑔/𝑚𝑔. 𝑚𝑖𝑛) are the rate constants of the pseudo-first-order and pseudosecond-order kinetics, respectively. the linearized form of the pseudo-first-order and pseudo-second-order is given by eqs. (9) and (10), respectively [22][31]. 𝑙𝑛(𝑞𝑒 − 𝑞𝑡) = ln 𝑞𝑒 − 𝐾1𝑡 … (9) 𝑡 𝑞𝑡 = ( 1 𝐾2𝑞𝑒 2) + ( 𝑡 𝑞𝑒 ) … (10) figure 8 shows the graphical presentation of the experimental adsorption data according to the pseudo-first-order and pseudo-second-order kinetics models. fig. 8. (a) pseudo-first-order and (b) pseudo-second-order kinetics models for adsorption of tetracycline onto tac. based on the values of correlation coefficients (𝑅2) presented in table 5, it was concluded that the pseudo-second-order kinetic model describes the experimental data for the adsorption of the tetracycline onto the tac. langmuir freundlich 𝐾𝐿 𝑞𝑚 𝑅2 𝐾𝐹 n 𝑅2 (l/mg) (mg/g) 0.063 45.662 0.9936 1.644 0.597 0.9692 y = -0.0007x + 2.8327 r² = 0.9001 2.64 2.66 2.68 2.7 2.72 2.74 2.76 2.78 2.8 2.82 2.84 2.86 0 100 200 300 l n (q eq t) time pseudo-first order kinetic y = 0.2058x + 22.851 r² = 0.9752 20 30 40 50 60 70 80 90 20 120 220 320 t/ q t time pseudo second order kinetic a b hala a. faisal al-khwarizmi engineering journal, vol. 19, no. 4, p.p. 115 (2023) 11 table 5, adsorption kinetics parameters of pseudo-first-order and pseudo-second-order rate equations pseudo-first-order pseudo-second-order 𝐾1 𝑞𝑒 𝑅2 𝐾2 𝑞𝑒 𝑅2 (min-1) (mg/g) (g/mg. min) (mg/g) 0.0007 9.2 0.9 0.0018 9.2 0.9752 4.3 thermodynamics study three thermodynamic parameters, including enthalpy change ∆𝐻0 , gibbs free energy change ∆𝐺0, and entropy change ∆𝑆0, were studied to investigate the thermodynamic behavior of the adsorption onto the tac. the gibbs free energy change ∆𝐺0 was determined by eq. (11) [32]. ∆𝐺𝑜 = 𝑅𝑇𝑙𝑛(𝐾𝑐) … (11) where r is the universal gas constant (𝑅 = 8.314 𝑘𝐽 𝑘𝑚𝑜𝑙. 𝐾⁄ ), t is the absolute temperature of the solution (k), and 𝐾𝑐 is the distribution coefficient that can be calculated by eq. (12). 𝐾𝑐 = 𝑞𝑒 𝐶𝑒 … (12) where qe is the amount of tetracycline adsorbed per unit weight of active carbon at equilibrium concentration (mg/g) and ce is the equilibrium concentration of tc (mg/l). the relation between the thermodynamic parameters enthalpy change ∆𝐻𝑜 , entropy change ∆𝑆𝑜, and gibbs free energy change ∆𝐺𝑜is given by eq. (13) [32]. ∆𝐺𝑜 = ∆𝐻𝑜 − 𝑇∆𝑆𝑜 … (13) substitution eq. (13) in eq. (11) gives ln 𝐾𝑐 = ∆𝑆° 𝑅 − ∆𝐻° 𝑅𝑇 … (14) the values of ln(kc) were calculated by eq. (12) at different temperatures. plotting ln (𝐾𝑐) vs. 1 𝑇 gives a linear relation from which the values of ∆𝐻𝑜 and ∆𝑆𝑜 can be calculated. figure 9 shows that the value of 𝐾𝑐 increases as the temperature increases. table 6 summarizes the thermodynamic parameters ∆go, ∆ho, and ∆so at various temperatures for the adsorption of tetracycline onto tac. fig. 9. 𝐥𝐧 𝑲𝒅 versus 𝟏 𝑻⁄ for the adsorption of tetracycline on tac. table 6, thermodynamic parameters for the adsorption of tetracycline by the active carbon ∆𝐺𝑜 (kj/mol) ∆𝑆𝑜(kj/mol k) ∆𝐻𝑜 (kj/mol) 30 𝑜𝐶 40 𝑜𝐶 50 𝑜𝐶 60 𝑜𝐶 -1.776 -2.114 -3.121 -3.987 75.73 21.333 y = -2566x + 9.1089 r² = 0.9549 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 0.0029 0.003 0.0031 0.0032 0.0033 0.0034 l n k c 1/t ac+tetra hala a. faisal al-khwarizmi engineering journal, vol. 19, no. 4, p.p. 115 (2023) 12 the negative values of ∆𝐺𝑜 indicate the spontaneous nature of the sorption process. the enthalpy change ∆ho has a positive value, which indicates that the adsorption process is physisorption and endothermic. the adsorption process will be favored by increasing the temperature. the entropy change has a positive sign, which reveals that the randomness at the interface of solid and liquid will increase during the adsorption of tetracycline [33]. 5. conclusion in this work, tea residue was successfully converted into activated carbon, which was then used to effectively adsorb tetracycline from an aqueous solution. the following parameters are the best for the adsorption process, which gives a removal percent of tetracycline of 97%: mixing duration of 230 min, acidity ph of 9, dosage of 0.39 g/25 ml of active carbon, and initial tetracycline concentration of 60 ppm. tetracycline's equilibrium adsorption on the prepared active carbon is accurately modeled using the langmuir model, with a maximum adsorption capacity of 45.662 mg/g. the pseudo-second-order model describes the adsorption kinetics and the reaction rate constant k2 is 0.0018 g/(mg. min). tetracycline adsorption on tea-activated carbon is endothermic and spontaneous, according to a thermodynamics study. acknowledgment we appreciate the help of the lab staff from the al-khwarizmi college of engineering's biochemical engineering department in carrying out various research-related laboratory tests. we would also like to express our gratitude to the state enterprise for drug industries and medical appliances, samara, iraq, for providing us with tetracycline and other chemicals. references [1] a. a. mohammed and s. l. kareem, “adsorption of tetracycline from wastewater by using pistachio shell coated with zno nanoparticles: equilibrium, kinetic and isotherm studies,” alexandria engineering journal, vol. 58, no. 3, pp. 917–928, 2019, http://doi: 10.1016/j.aej.2019.08.006. 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(2023) 1-15، صفحة 4، العدد19دجلة الخوارزمي الهندسية المجلم ل هالة علي فيص 15 تحضير وتوصيف وكفاءة امتصاص التتراسيكلين للكربون المنشط المشتق من بقايا الشاي **عالء كريم محمد *هالة علي فيصل ****وان نور رسالم وان عيسى ***ناديا حسين السباني حيائية/ كلية الهندسة الخوارزمي/ جامعة بغدادالقسم الهندسة الكيميائية ا**،* قسم الهندسة الكيميائية/ كلية هندسة النفط والغاز/ جامعة الزاوية/ ليبيا *** العمليات/ كلية الهندسة والبيئة / جامعة كيبانجسان/ ماليزيا**** قسم الهندسة الكيميائية وهندسة dr.alaa@kecbu.uobaghdad.edu.iq*البريد االلكتروني: kecbu.uobaghdad.edu.iq2018israa_msc@**البريد االلكتروني: n.asbani@zu.edu.ly***البريد االلكتروني: wannorroslam@ukm.edu.my****البريد االلكتروني: الخالصة الخصائص الفيزيائية والكيميائية وكفاءة االمتصاص للكاربون دراسة( من بقايا الشاي المستخدم. تمت tacالكربون المنشط )في هذه الدراسة، تم تحضير درجة مئوية، وهما الخطوتان الرئيسيتان في عملية 350( والكربنة عند kohباستخدام هيدروكسيد البوتاسيوم ) التنشيط تمتالمنشط المنتج. ان عملية ( من المحلول المائي. تمت دراسة متغيرات مختلفة إلظهار تأثيرها على كفاءة tcالتتراسيكلين ) المحضر المتصاصتم استخدام الكربون المنشط التحضير. بون . تم تشخيص الكر ، وكمية المادة الممتزة، ووقت االمتزازph ، ودرجة حموضة المحلول tc. هذه المتغيرات هي: التركيز األولي لـ tcامتصاص ( ، وحيود األشعة السينية sem( ، والفحص المجهري اإللكتروني )ftirالنشط المحضر باستخدام التحليل الطيفي لألشعة تحت الحمراء لتحويل فورير ) (xrd و ، )brunauer-emmett-teller (bet) تم تمثيل عملية امتصاص .tc على الكربون المنشطtac بشكل فعال بواسطة نموذجlangmuir . . وجد ان اقصى امتصاص التتراسيكلين على الكربون langmuirالقصوى المحددة باستخدام نموذج tcتؤدي زيادة درجة الحرارة إلى زيادة قدرة امتصاص ملي غرام/ غرام. لوحظ ان حركيات االمتزاز تتمثل بشكل جيد من خالل الدرجة الثانية الزائفة. توضح دراسة الديناميكا الحرارية 45.662النشط المحضر تبلغ ماص للحرارة وتلقائي. tacعلى tcلالمتصاص، أن امتصاص mailto:dr.alaa@kecbu.uobaghdad.edu.iq mailto:israa_msc2018@kecbu.uobaghdad.edu.iq mailto:n.asbani@zu.edu.ly mailto:wannorroslam@ukm.edu.my _13-30_ mohammed m. hasan mohammed m. hasan /al-khwarizmi engineering journal, vol.3, no.3, pp 13-30 (2007) 13 al-khwarizmi engineering journal al-khwarizmi engineering journal, vol.3, no.3, pp 13-30 (2007) optimum design of stiffened square plates for longitudinal and square ribs mohammed m. hasan department of mechanical engineering college of engineering university of anbar (received 14 march 2007; accepted 7 june 2007) abstract for a given loading, the stiffness of a plate or shell structure can be increased significantly by the addition of ribs or stiffeners. hitherto, the optimization techniques are mainly on the sizing of the ribs. the more important issue of identifying the optimum location of the ribs has received little attention. in this investigation, finite element analysis has been achieved for the determination of the optimum locations of the ribs for a given set of design constraints. in the conclusion, the author underlines the optimum positions of the ribs or stiffeners which give the best results. keywords: optimum, stiffeners, plate, stress, fea. introduction the wide use of stiffened structural elements in engineering began in the nineteenth century, mainly with the application of steel plates for the hulls of ships and with development of steel bridges and aircraft structures. stiffened plates now find applications in modern industry. stiffeners in a stiffened plate make it possible to resist highly directional loads, and introduce multiple load paths that may provide protection against damage and crack growth under both compressive and tensile loads. the biggest advantage of the stiffeners, though, is the increased bending stiffness of the panel with a minimum of additional material, which makes these structures highly desirable for out-of-plane loads and destabilizing compressive loads. in addition to the advantages already found in using them, there should be no doubt that stiffened plates designed with optimization techniques will be bring many benefits like swings in material usage, cost, better performance, etc. several researches have recently been published regarding the stiffened plates and there applications in ships, bridges, bunkers, tank roofs, offshore structures, vehicles, etc. [1-7]. in general, analytical and exact variational solutions for plate or shell behavior are desirable because of their ease of use and the insight they provide to the designer. specific geometric effects can be ascertained from these solutions. however, these solutions are generally only applicable for small mohammed m. hasan /al-khwarizmi engineering journal, vol.3, no.3, pp 13-30 (2007) 14 deflections. numerical techniques, such as finite element analysis, boundary element analysis, and finite difference analysis, can be more accurate in predicting stresses and deflections, especially for large deflections. unfortunately, these techniques generally require more effort to use and may not supply the same insight as analytical or exact variational solutions. the use of plate theory is appropriate for the analysis of plates or shells; therefore, this work has been achieved by using the finite element software package msc/nastran with plate bending and shell elements. finite element analysis during the last three decades considerable advances have been made in the applications of numerical techniques to analyze basic structural elements as well as highly sophisticated structures in various fields of engineering. among these numerical procedures, the finite element methods are the most frequently used today [8]. finite element procedures have become an important and frequently indispensable part of engineering analysis and design. finite element computer programs are now widely used in practically all branches of engineering [9]. applications range from deformation and stress analysis of automotive, aircraft, building, and bridge structures to field analysis of heat flux, fluid flow, magnetic flux, seepage, and other flow problems. with the advances in computer technology and cad systems, complex problems can be modeled with relative ease. several alternative configurations can be tried out on a computer before the first prototype is built [10]. the development of finite element methods for the solution of practical engineering problems began with the advent of the digital computer. that is, the essence of a finite element solution of an engineering problem is that a set of governing algebraic equations is established and solved, and it was only through the use of the digital computer that this process could be rendered effective and given general applicability. these two propertieseffectiveness and general applicability in engineering analysis are inherent in the theory used and have been developed to a high degree for practical computations, so that finite element methods have found wide appeal in engineering practice. design constraints three cases of design constraints are used in this work. figure (1-a) shows the first case where all of the edges of the square plate are fixed. figure (1-b) represents the second case where two edges are fixed and the other two edges are free. in the third case, figure (1-c) three edges of the square plate are fixed and one is free. types of ribs or stiffeners several types and shapes of ribs or stiffeners may be used to strength plates or shells to increase the stiffness of these structures like flat, l, trapezoidal or other shape [3]. this paper deals with flat ribs or stiffeners for longitudinal and square shapes. for all of the design constraints cases used in this work, one or two longitudinal flat ribs or stiffeners are used; whereas square flat ribs or stiffeners are used to strength the wholly clamped edges plate only, as shown in figures (2 – 5). mohammed m. hasan /al-khwarizmi engineering journal, vol.3, no.3, pp 13-30 (2007) 15 theory and simulation in many of the available references on the analysis of stiffened plates, the approximate method proposed by huber is used. based on the orthotropic plate theory, this method analyzes the plate stiffener system as a plate of equivalent uniform thickness. it neglects the in-plane displacement of the middle plane of the plate. in an improved method presented by clifton et al., the eccentricity and torsional rigidity of the stiffeners are taken into account, the effect of the stiffeners is smeared out. the governing equations are solved for a simply supported plate and a plate with bridge-type boundary conditions [11]. large numbers of researches which deal with the analysis of stiffened plates use the finite element computer programs such marc, ansys, cares/life, patran, and nastran which is used in this work. structural analysis consists of static analysis, normal modes analysis, and buckling analysis. the static analysis equation is: [k]{u} = {f} where k is the system stiffness matrix (generated automatically by msc/nastran, based on the geometry and properties), f is the vector of applied forces, and u is the vector of displacements that the program computes. once the displacements are computed, the finite element software package uses these to compute element forces, stresses, reaction forces, and strains. the applied forces may be used independently or combined with each other. the loads can also be applied in multiple loading subcases, in which each subcase represents a particular loading or boundary condition. multiple loading subcases provide a means of solution efficiency, whereby the solution time for subsequent subcases is a small fraction of the solution time for the first. the accuracy of numerical results depends on the number of the elements used in the descritization scheme. the resolution increases when the number of elements increases. in order to investigate the optimum locations of the ribs or stiffeners, fine meshes with the maximum permissible number of elements have been used in order to easily change the positions of the ribs and to freely control it. all of the models used are of the same dimensions (1m × 1m × 2mm) and same material (stainless steel) with the following properties: modulus of elasticity, e = 196.5 gpa modulus of rigidity, g = 77.221 gpa poisson’s ratio, ν = 0.27 mass density, ρ = 7834.6 kg/m3 every model consists of quadrilateral plate bending and shell elements. all of these elements are subjected to uniform hydrostatic pressure of (p = 2.5 kpa) to work safely within elastic limit. it is found by experiments that initiation of yielding in most materials is predicted fairly well by either the maximum shearing stress criterion or the octahedral shearing stress criterion which gives the same results as does the energy of distortion criterion [12]. so, in this work, von-mises stresses have been proposed. to achieve this study, first, one longitudinal flat rib is used to strength the plate for the three cases of design constraints that discussed previously, as shown in figure (2). the width of the stiffener (w) is used to be (5 cm) and the thickness of it (t) varies from (2 to 6 mm) and located at the middle of the plate, on one or two of the plate sides as shown in figure (6). depending upon the results of these cases, two mohammed m. hasan /al-khwarizmi engineering journal, vol.3, no.3, pp 13-30 (2007) 16 longitudinal and parallel ribs are used with the same dimensions to stiffen the plate for the same design constraints. this time, the positions of stiffeners are varied from the center line of the plate to the edges, as shown in figure (3). as an individual situation, one longitudinal rib parallel to the free edge of the third case of the design constraints is used for the same purpose. as shown in figure (4), this time, location of the rib varies from one edge to the free one on one and two of the plat sides. finally, one square stiffener is used to strength the clamped square plate, as shown in figure (5-a). position of this stiffener varies from the center of the plate to the fixed edges on one and two of the plate sides. width and thicknesses of the rib are the same of those used previously. results and discussions to strength a plate, stiffeners may be used on one or two of its sides. to show the best way, one longitudinal rib with different thicknesses is used to stiffen the plate. figures (8 & 9) show the effect of using the rib on one side and two sides respectively on the maximum stress for the three design constraints (a, b, and c) which discussed in article (3). it is obvious that the use of the rib on two sides is the best for all cases and the use of it on one side gives bad results for small thicknesses. maximum deflection is the same when using the stiffener on one or two sides, as shown in figure (10). the second step is using two longitudinal and parallel ribs on the two sides. figures (11 – 16) show the variation of maximum stress and deflection with the change of distance between the two ribs for the three cases of the design constraints. for the first case of the design constraints, it is clear that the use of ribs with thickness more than the plate thickness give good results when the two stiffeners are located together on the center line of the plate, as shown in figure (11). so, the stiffness of the plate may be increased by increasing the width of the one longitudinal stiffener that used before. for the second and third cases of the design constraints, two stiffeners may be used with a certain thickness and in between displacement to reduce the maximum stress induced, as shown in figures (13 – 16). as shown in figure (9), there is no importance of using one longitudinal rib perpendicular to the free edge of the third case of the design constraints; therefore, this rib may be used parallel to the free edge. for different locations, figures (17 & 18) show that the use of the rib on two sides is better than using it on one side. also, there is an optimum location for the rib depending on its thickness. similarly, when a square rib is used to strength the wholly clamped square plate, there is an optimal position depending upon thickness of the stiffener and the use of this stiffener on two sides is the best, as shown in figures (20 & 21). significantly, a good location is appeared at the edges of the plate when using a small thickness for the rib. this may enable us to use two square ribs, one clamped with the edges and the other at a certain position depending upon its thickness, as shown in figure (5-b). for the first case of the design constraints used in this work where the plate is fixed from all its edges, it is noted that the use of a longitudinal rib may gives better results than using a square stiffener. two perpendicular ribs at the center lines of the plate, as shown in figure (7) may also give good results. as a comparison between some cases of strengthening the wholly clamped plate, results of using some longitudinal and square stiffeners are shown in table (1). mohammed m. hasan /al-khwarizmi engineering journal, vol.3, no.3, pp 13-30 (2007) 17 conclusions: from the results of this work, it is obvious that using stiffeners on both of the two sides of a square plate gives better results than using the same size of these ribs on one side. this is the primary choice to increase the stiffness of the plate for all of the design constraints used. the choice does not affect the maximum deflection. for the first case of the design constraints, the use of one longitudinal stiffener with certain dimensions at the center line of the plate may be better than using one longitudinal or square stiffener. to use square stiffeners, one may locate a thin rib on the edges and another at a position depends upon the dimensions of this stiffener. for the second case of the design constraints, two parallel stiffeners at certain locations give better results than using one rib. finally, in the third case, one longitudinal stiffener may be located parallel to the free edge of the plate as an optimal choice, in order to get good results. mohammed m. hasan /al-khwarizmi engineering journal, vol.3, no.3, pp 13-30 (2007) 18 (a) (b) (c) fig.(1) the three design constraints used (a) (b) (c) fig.(2) one longitudinal rib fixed fixed fixed fixed fixed fixed free fixed fixed fixed free free mohammed m. hasan /al-khwarizmi engineering journal, vol.3, no.3, pp 13-30 (2007) 19 (a) (b) (c) fig.(3) two parallel longitudinal ribs fig.(4) one longitudinal rib parallel to the free edge x x/2 x/2 x x/2 x/2 x x/2 x/2 h mohammed m. hasan /al-khwarizmi engineering journal, vol.3, no.3, pp 13-30 (2007) 20 (a) (b) fig.(5) one and two square ribs (a) (b) fig.(6) side view of the stiffened plate fig.(7) two perpendicular longitudinal ribs fixed fixed fixed fixed l t t p w t/2 t/2 t p w fixed fixed fixed fixed l1 l2 mohammed m. hasan /al-khwarizmi engineering journal, vol.3, no.3, pp 13-30 (2007) 21 0 100 200 300 400 500 600 0 1 2 3 4 5 6 7 thickness of the rib (t), mm m ax . s tr es s, m pa . a b c fig (8) effect of using one longitudinal rib on one side on the maximum stress 0 50 100 150 200 250 300 350 0 1 2 3 4 5 6 7 thickness of the rib (t), mm m ax . s tr es s, m pa . a b c fig (9) effect of using one longitudinal rib on two sides on the maximum stress mohammed m. hasan /al-khwarizmi engineering journal, vol.3, no.3, pp 13-30 (2007) 22 0 10 20 30 40 50 60 0 1 2 3 4 5 6 7 thickness of the rib (t), mm m ax . d ef le ct io n, m m . a b c fig (10) effect of using one longitudinal rib on one or two sides on the maximum deflection 50 75 100 125 150 175 0 10 20 30 40 50 60 70 80 90 100 x, cm. m ax . s tr es s, m pa . t = 0 mm t = 2 mm t = 4 mm t = 6 mm fig (11) effect of using two parallel ribs on the maximum stress for the first case of the design constraints mohammed m. hasan /al-khwarizmi engineering journal, vol.3, no.3, pp 13-30 (2007) 23 0 5 10 15 20 25 0 10 20 30 40 50 60 70 80 90 100 x, cm. m ax . d ef le ct io n, m m . t = 0 mm t = 2 mm t = 4 mm t = 6 mm fig (12) effect of using two parallel ribs on the maximum deflection for the first case of the design constraints 100 125 150 175 200 225 250 275 300 325 0 10 20 30 40 50 60 70 80 90 100 x, cm. m ax . s tr es s, m pa . t = 0 mm t = 2 mm t = 4 mm t = 6 mm fig (13) effect of using two parallel ribs on the maximum stress for the second case of the design constraints mohammed m. hasan /al-khwarizmi engineering journal, vol.3, no.3, pp 13-30 (2007) 24 0 10 20 30 40 50 60 0 10 20 30 40 50 60 70 80 90 100 x, cm. m ax . d ef le ct io n, m m . t = 0 mm t = 2 mm t = 4 mm t = 6 mm fig (14) effect of using two parallel ribs on the maximum deflection for the second case of the design constraints 150 175 200 225 250 275 300 325 0 10 20 30 40 50 60 70 80 90 100 x, cm. m ax . s tr es s, m pa . t = 0 mm t = 2 mm t = 4 mm t = 6 mm fig (15) effect of using two parallel ribs on the maximum stress for the third case of the design constraints mohammed m. hasan /al-khwarizmi engineering journal, vol.3, no.3, pp 13-30 (2007) 25 20 25 30 35 40 45 50 55 60 0 10 20 30 40 50 60 70 80 90 100 x, cm. m ax . d ef le ct io n, m m . t = 0 mm t = 2 mm t = 4 mm t = 6 mm fig (16) effect of using two parallel ribs on the maximum deflection for the third case of the design constraints 150 200 250 300 350 400 450 500 0 10 20 30 40 50 60 70 80 90 100 h, cm m ax . m is es s tr es s, m pa . t = 0 mm t = 2 mm t = 4 mm t = 6 mm fig (17) effect of using one longitudinal rib on one side parallel to the free edge for the third case of the design constraints on the maximum stress mohammed m. hasan /al-khwarizmi engineering journal, vol.3, no.3, pp 13-30 (2007) 26 50 100 150 200 250 300 350 0 10 20 30 40 50 60 70 80 90 100 h, cm m ax . m is es s tr es s, m pa . t = 0 mm t = 2 mm t = 4 mm t = 6 mm fig (18) effect of using one longitudinal rib on two sides parallel to the free edge for the third case of the design constraints on the maximum stress 0 10 20 30 40 50 60 0 10 20 30 40 50 60 70 80 90 100 h, cm m ax . d ef le ct io n, m m t = 0 mm t = 2 mm t = 4 mm t = 6 mm fig (19) effect of using one longitudinal rib on one side parallel to the free edge for the third case of the design constraints on the maximum deflection mohammed m. hasan /al-khwarizmi engineering journal, vol.3, no.3, pp 13-30 (2007) 27 75 100 125 150 175 0 10 20 30 40 50 60 70 80 90 100 l, cm. m ax . s tr es s, m pa . t = 0 mm t = 2 mm t = 4 mm t = 6 mm fig (20) effect of using one square rib on one side on the maximum stress for the first case of the design constraints 75 100 125 150 175 0 10 20 30 40 50 60 70 80 90 100 l, cm. m ax . s tr es s, m pa . t = 0 mm t = 2 mm t = 4 mm t = 6 mm fig (21) effect of using one square rib on two sides on the maximum stress for the first case of the design constraints mohammed m. hasan /al-khwarizmi engineering journal, vol.3, no.3, pp 13-30 (2007) 28 5 7 9 11 13 15 17 19 21 23 25 0 10 20 30 40 50 60 70 80 90 100 l, cm. m ax . d ef le ct io n, m m . t = 0 mm t = 2 mm t = 4 mm t = 6 mm fig (22) effect of using one square rib on one or two sides on the maximum stress for the first case of the design constraints type of stiffener dimention of stiffener location of stiffener percentage increasing in weight percentage reduction in maximum stress one longitudinal rib w = 5 cm, t = 6 mm at the center line of the plate 15 % 47.55 % one longitudinal rib w = 10 cm, t = 6 mm at the center line of the plate 30 % 50.2 % two perpendicular ribs w = 10 cm, t = 6 mm for each one at the center line of the plate (fig. 7) 57 % 70.14 % square stiffener w = 5 cm, t = 6 mm at the best position (l = 80 cm) 51 % 45.56 % table (1) comparison between some cases of strengthening the wholly clamped edges plate mohammed m. hasan /al-khwarizmi engineering journal, vol.3, no.3, pp 13-30 (2007) 29 references [1] j. farkas, structural optimization as a harmony of design, fabrication and economy, structural and multidisciplinary optimization, vol. 30., no. 1., pp. 35-45, july, 2005. 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[14] s.p. timoshinko and k.s. woinowsky, theory of plates and shells, second edition, tokyo, mcgraw-hill kogakusha ltd, 1959. mohammed m. hasan /al-khwarizmi engineering journal, vol.3, no.3, pp 13-30 (2007) 30 الع طولیة ومربعةالتصمیم األمثل للصفائح المربعة المقواة بأض محمد مدحت حسن قسم الھندسة المیكانیكیة جامعة األنبار/ كلیة الھندسة : ةـــــــــالخالص إن التراكی ب المؤلف ة م ن الص فائح أو األغش یة المعدنی ة والمعرض ة لحال ة تحمی ل معین ة م ن لح د اآلن ف إن تقنی ات . الممك ن زی ادة ص البتھا بش كل ملح وظ ع ن طری ق إض افة أض الع مقوی ة إن المس ألة األكث ر أھمی ة .األمثلیة تتناول في الدرجة األولى وال ى ح د بعی د حج م األض الع المقوی ة لق د ت م اس تخدام طریق ة . ھي تحدید الموقع األمثل لألضالع المقویة والتي ل م ت ولى إال اھتمام ا قل یال .ع المقویة ولحاالت تثبیت تصمیمیة مح ددة التحلیل بالعناصر المحددة إلیجاد المواقع المثلى لألضال .یحدد الباحث في االستنتاجات المواقع المثلى لألضالع المقویة والتي تعطي أفضل النتائج this is an open access article under the cc by license : al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 21, no. 4, december, (2025), pp. 82-92 performance evaluation and optimisation of spectrum management in communication systems by ga ahmed a. thabit 1*, bassam h. abd 2, ali j. al-askery 3 and haider w. oleiwi4 electrical engineering technical college, middle technical university, baghdad, iraq 1,3 2electrical engineering college, university of technology, baghdad, iraq 4department of electronic and electrical engineering, brunel university london, uk *corresponding author’s email: ahmed.thabit@mtu.edu.iq (received 12 june 2025; revised 7 october 2025; accepted 27 october 2025; published 1 december 2025) https://doi.org/10.22153/kej.2025.10.002 abstract whilst wireless communication technologies proliferate, putting extra demand on the finite radio frequency spectrum and leading to issues of congestion, underutilisation and interference, this dissertation presents a modern spectrum management model on the binary genetic algorithm (bga) capable of improving detection accuracy and adaptive spectrum access in cognitive radio networks (crns). bga follows binary encoding to determine optimum weighting factors for secondary users in a crn scenario with a much faster performance and better reliability than conventional genetic approaches. in the cooperative spectrum-sensing scheme proposed in this paper, multiple secondary users will forward their local sensing outcomes to a fusion centre in which bga optimisation will fine-tune the weighting coefficients throughout the soft decision fusion mechanism. the algorithm then evolves from one generation to the next through the application of selection, crossover and mutation operations to discover the best configuration. extensive simulation experiments were conducted to study the effects of the critical genetic parameters of mutation probability, crossover rate and population size on detection capability. the results indicate that the optimised bga framework can achieve detection probability close to 96%, false alarm rate of 0.1, mutation rate of 0.12 and bit error rate of around 7 × 10⁻⁵ even when the signal-to-noise ratio is extremely low at –15 db. in addition, the comparative evaluation showed the definite superiority of the proposed algorithm when tested against conventional algorithms, such as energy detection, matched filtering and neural network-based convolutions, when subjected to challenging and noise-prone conditions. the work further affirms the applicability of evolutionary algorithms in enhancing the cognitive intelligence of crs and presents a scalable solution for spectrum management in existing 5g systems and future 6g frameworks. keywords: cognitive radio; crossover; detection rate; dynamic spectrum access; genetic algorithm; optimisation; spectrum sensing 1. introduction considerable changes in social automation and connectivity have been brought about by groundbreaking advances in technology related to wireless communication infrastructures. changes in this area are responsible for the exponential increase in the number of connected devices and user demands, thereby complicating and aggravating problems of spectrum congestion and the efficient use of limited frequency resources. additionally, all these limitations affect the overall performance and quality of service of modern-day wireless networks [1,2]. the modern generation of wireless technology is evolving to meet the insatiable appetite for everincreasing data transfer rates along with low latencies and the efficient usage of the available spectrum as well as 3g rendering mobile multimedia capabilities, thus establishing 2g as digital voice communications. advanced methods such as lte, ofdm and mimo were utilised by 4g implementations to provide services for data at high speeds. although modern-day 5g networks mailto:ahmed.thabit@mtu.edu.iq https://doi.org/10.22153/kej.2025.10.002 ahmed a. thabit al-khwarizmi engineering journal, vol. 21, no.4, pp. 8292 (2025) 83 offer technical advantages and opportunities, they also came with problems regarding propagation caused by its very wide frequency ranges: under 1 ghz, mid-band (1-6 ghz) and even millimetrewave spectra [2,3]. the frequency allocation implemented in the 5g implementation strategy is illustrated in fig. 1. fig. 1. 5g-based electromagnetic spectral part [3] spectral crunch refers to the limitation of a static system employing spectrum allocation with the power of current extreme growth in mobile connectivity. therefore, dsa technologies play an important role in addressing that domain. in particular, they enable wireless devices to intelligently exploit available frequency bands depending on real-time changes in the environment. this opportunistic access of dsa considerably enhances spectral efficiency through the fair treatment of different users and minimum interference. a few characteristic application scenarios of dsa implementation emphasising its important role in the prevalent modern wireless architecture are shown in fig. 2 [4,5]. fig. 2. dsa applications cr innovation will be most instrumental in promoting dsa applications that enable radios to detect, characterise and adapt to the spectrum conditions. cr devices are capable of detecting unutilised frequency bands, also known as spectrum holes or white spaces, to access them dynamically without affecting any primary licensed user. this facility draws best applicability in densely populated metropolitan areas, where spectra congestion is at its worst [6]. the facilities and capabilities of telecommunication systems have witnessed dramatic changes via the ai and ml in the application of predicting traffic patterns and adjustment of sensing algorithms, thus improving performance. past studies have shown that the next advanced generation systems networks (i.e. 6g) allow new applications with different requirements in the dynamic allocation of resources [7, 8]. achieving high performance with good quality requires strong optimisation algorithms that are capable of managing nonlinear and dynamic situations. advancements in 6g devices and the application of terahertz frequency range may sound futuristic, but it could also lead to greater complexities in the distribution and management of the spectrum. this makes genetic algorithms (gas) one of the more promising bio-inspired methods for improving precision in spectrum sensing and resource allocation within cognitive radio networks (crns) [9–11]. in this paper, we present an improved ga-based detection system to enhance detection performance and spectrum utilisation efficiency. the effectiveness of the proposed method is tested against earlier established techniques, which appeared in various papers, via simulative comparison with the aim of establishing its superiority in the stage of variety of wireless medium. the particular contributions of this work are as follows: 1) formulating a genetic algorithm-based joint detection model that enhances the accuracy of smart selection fusion methodologies; 2) using a fitness-based choice, multipoint crossing and genetic variation to improve on the weighting vector for secondary users (sus); and 3) testing performance by extensive simulations, thus ensuring good detection reliability even under low snr. the tuning of genetic factors, such as population, mutation and crossover frequency, will have tremendous impacts on overall performance in demonstrating ga’s capability for real-time cr optimisation. ahmed a. thabit al-khwarizmi engineering journal, vol. 21, no.4, pp. 8292 (2025) 84 the remaining parts of this work are organised as follows: section 2 presents a brief overview of ga with crn, section 3 discusses the details related to the introduced system model, section 4 talks about the simulation outcomes, section 5 talks about the comparison of the proposal with the current state of the art and finally, section 6 ends the paper by presenting the conclusions. 2. background gas are a category of biologically inspired techniques for optimisation based on the principles underlying biological evolution. because of their versatility and robustness, gas are widely used to deal with difficult, multiple optimisation problems. in today’s mobile communication systems, gas have also been remarkably effective in optimising rf utilisation. a ga starts off with a heterogeneous population of possible solutions, each represented as a chromosome. the actions are then evaluated by a fitness function as the measure of the efficiencies of each in dealing with the problem at hand. next, this population is subjected to several generational successions under the operations of selection, crossover and mutation, similar to actual genetic processes [12–14]. through succeeding generations, the population approaches optimal or near-optimal solutions by preserving and enhancing the most fit people. in wireless systems, genetic algorithms have shown significant potential in numerous critical domains, including spectrum allocation, which involves the successful allocation of frequency bands to reduce interference whilst satisfying the demands of diverse users. crns have an enhanced precision in identifying main users (pus) and selecting suitable transmission bands based on environmental circumstances [15]. power control and spectrum sharing involves the optimisation of transmission power and resource allocation procedures to enhance reliability and mitigate cochannel interference. although successful, gas are sensitive to specific design factors, such as mutation rate, crossover frequency and the number of individuals, thus requiring meticulous adjustment to guarantee convergence and prevent premature stagnation [16]. in signal processing, gas have demonstrated promising outcomes in complex situations involving multiple-input multiple-output (mimo) systems and intricate modulation schemes (e.g. mpsk), by effectively manoeuvering through noisy signal environments and improving detection performance [17–19]. in conclusion, gas offer a versatile and effective framework for dynamic spectrum management, especially in future-oriented communication networks in which real-time improvement is critical [20]. 3. system model the significant role of sensing stage in the crn systems is highly affected due to bad environments (e.g., fading and additive white gaussian noise (awgn)) in communication channels. the soft decision fusion (sdf)-based cooperative scheme is employed so as to improve detection reliability. the architecture consists of multiple sus, so-called relays, forwarding sensed information to a central fusion centre (fc). the redesigned cooperative system model with updated notations is shown in fig. 2 [21–25]. 3.1. primary-relay channel modelling each secondary user performs local spectrum sensing to detect the presence of a primary user (pu). the sensing process is formulated as a binary hypothesis test: under the null hypothesis h₀ (no pu signal): rk[m] = ηk[m], …(1) under alternative hypothesis h₁ (pu present): rk[m] = αk·s[m] + ηk[m], …(2) where rk[m] denotes the m-th received signal sample at the k-th su. the variable ηk[m] represents the awgn at su-k, assumed to have zero mean with variance σ²ηₖ. in addition, αk denotes the sensing channel gain between the primary user and the kth su, incorporating effects, such as shadowing and multipath fading. the pu’s transmitted signal s[m] is modelled as a zero-mean gaussian random process with variance σ²s. table 1 provides a reference for the variables used in fig. 3, along with their corresponding definitions, as described in the system model. ahmed a. thabit al-khwarizmi engineering journal, vol. 21, no.4, pp. 8292 (2025) 85 table 1, variable definitions used fig. 3. cooperative sensing system model using updated variable notations. 3.2. relay-fusion channel modelling this subsection describes the transmission from su to fc as seen in equation 3: yk[m]= τk·βk·rk[m] + ξk[m], …(3) where τk is the transmission power of su-k, βk is the amplitude gain of the reporting channel between su-k and the fc and ξk[m] is the awgn at the fc from su-k, as well as a zero-mean variance of σ²ξₖ. substituting the hypotheses into (3), under h₀: yk[m] = τk·βk·ηk[m] + ξk[m], …(4) yk[m] = τk·βk·αk·s[m] + τk·βk·ηk[m] + ξk[m] …(5) however, under h₁: zk = σ{m=1}n |yk[m]|². …(6) let zk denote the energy estimate computed at the fc from su-k’s signal: this test statistic zk approximates a gaussian distribution via the central limit theorem. its statistical parameters under each hypothesis are given as follows, where μ₀ₖ and μ₁ₖ are the expected values of zk under h₀ and h₁, respectively: μ₀ₖ = n·(τk²·βk²·σ²ηₖ + σ²ξₖ), …(7) μ₁ₖ = n·(τk²·βk²·αk²·σ²s) + μ₀ₖ. …(8) the global test statistic z at the fusion centre is a weighted linear combination of all individual energy statistics: z = σ{k=1}k λk·zk, …(9) where λk is the weight assigned to su-k, satisfying the normalisation constraint σ λk² = 1. the performance is characterised using the q-function: pf = q((β μ₀) / σ₀), …(10) pd = q((β μ₁) / σ₁). …(11) each su forwards its observations to the fc through an orthogonal reporting channel. the received signal at the fc from the k-th su is given by: where β is the detection threshold at the fc and (σ₀, σ₁) are the standard deviations of z under h₀ and h₁, respectively. 3.3. conventional weighting strategies in sdf the following classical methods are used to define the weighting coefficients λk: equal gain combining (egc): λk=1/√k, assigning equal weight to all sus. maximal ratio combining (mrc): λk ∝ snrk, where snrk is the signal-to-noise ratio at su-k. normal deflection coefficient (ndc): λ ∝ σ₀⁻¹·θ, where θ = μ₁ μ₀. modified deflection coefficient (mdc): λ∝σ₁⁻¹·θ, using covariance under h₁ instead. these strategies aim to enhance detection probability by emphasising more reliable su measurements in the fusion process. variable definition s[m] signal transmitted by the primary user (pu) αₖ channel gain between pu and the kth secondary user (suₖ) rₖ[m] received signal at the k-th secondary user (su) ηₖ[m] noise at the k-th su (awgn) τₖ transmit power of suₖ βₖ channel gain between suₖ and fusion centre (fc) ξₖ[m] noise at the fc from suₖ yₖ[m] signal received at fc from suₖ zₖ energy detection result of suₖ at the fc λₖ weighting coefficient assigned to suₖ z final global test statistic at the fc ahmed a. thabit al-khwarizmi engineering journal, vol. 21, no.4, pp. 8292 (2025) 86 3.4. proposed bga-based cooperative spectrum sensing to enhance detection performance and spectrum utilisation in crns, a binary genetic algorithm (bga) was employed to optimise the weighting coefficients used in the sdf process. the proposed bga-based model operates by evolving a population of candidate weighting vectors through successive generations, guided by fitness-driven selection, crossover and mutation operations, selection and genetics. the model is capable of addressing straightforward tasks (e.g. image generation and highly complex challenges), including deep learning optimisation and stochastic problem solving. ga deals with a set of possible solutions, each representing a particular answer to the problem in question. the procedure starts with an initial random population of the encoded solutions termed genomes. next, these solutions are evolved to different generations using biologically motivated operations for selection, crossover and mutation. the quality of each genome is assessed using a fitness evaluation function relevant to the specific problem. if the stopping criterion has not yet been met, individuals with higher fitness values are selected to form the next generation. these individuals undergo crossover to exchange genetic material and mutation to introduce variability. the offspring produced by this process are then evaluated, and the most promising amongst them are carried forward. the abovementioned evolutionary loop continues until a predefined condition is satisfied (e.g. reaching a maximum number of generations or achieving a target performance). a conceptual overview of this procedure is shown in fig. 4. the strategy generates a seed group of potential solutions and normalises them to meet restrictions, aiming to optimise identification effectiveness by determining the ideal collection of grading vector elements. if the algorithm exceeds the specified limit, the most effective scalar values are then selected. let c s and l1, l2…lc be the soft decisions of s1, s2…sc, respectively, on the presence of signals, where c is the complete number of sus. yi represents the weighting vector of the ith individual that consists of y1, y2….yc. in the case of ||yi ||=1, dp is the detection rate. the fitness value for the ith individual is defined as: . the objective of the selection step is to use crossover and mutation to identify the most advantageous genomes for replication. a higher fitting value indicates a superior option: funi=dp(yi). …(12) here, the roulette wheel selection approach is employed. the notation pi represents the probability of choosing the ith individuals. 𝑑𝑖 = fun𝑖 ∑ fun𝑖 𝑖𝑛𝑑𝑖𝑣𝑖𝑑𝑢𝑎𝑙𝑠 𝑖−1 …(13) fig. 4. flowchart of the proposed ga based on privilege, the genes that have the greatest likelihood of occurring will be passed down to the following population. crossover occurs following the selection procedure. the crossover procedure commences by pairing the chosen genes from the existing generation to produce a new progeny population. these partnerships, equivalent to biological parents, are selected randomly out of the current pool via a statistical picking technique. a randomly selected function, such as rand, is then ahmed a. thabit al-khwarizmi engineering journal, vol. 21, no.4, pp. 8292 (2025) 87 employed to ascertain candidate numbers, which are subsequently rounded to the nearest integers to align with real chromosome positions within a certain population size (e.g. 5 individuals). after selecting both parental genomes, a multipoint crossover approach is employed, in which genetic material is exchanged between pairs at several randomly established crossover locations. this process mimics the biological process of genetic recombination, thus promoting diversity and helping the algorithm explore a broader solution space. in the tested configuration, sample random values (i.e. (0.67, 0.23) and (0.12, 0.91)) are generated to guide the selection and crossover points. the resulting selected chromosomes for crossover are indexed as x = [2, 4] and y = [5, 1], representing the parental combinations for that iteration. the complete crossover and mutation procedures are depicted in figs. 5 and 6, respectively. these figures offer a visual analogy similar to shuffling and splitting strands of dna to create new genetic expressions in the next generation of solutions. fig. 5. bga crossover operation fig. 6. the operation of mutation in the case of bga mutation, all the parameters that might be changed are ≈ (mutation rate * population * bit size * number of variables). at a pace of a single chromosomal bit at a time, the suggested bit switches into the matching bipolar digit after the row and column numbers are randomly selected. the process by which bga mutations work is presented in fig. 4. the mutation procedure contributes to the creation of a new search space. in summary, the following is how the suggested ga-based system for collaborative spectral monitoring operates from a to g: a: place t is set to 0 to produce an arbitrary population of genomes. every population genome is (c*x) bits long, where c represents the overall number of sus in the system and x represents the bits in every genome. b: each chromosome will be decoded into an array that corresponds to it in the arbitrary group. the identification accuracy is enhanced via the weighted parameters set of y= [y1 y2 y3,…yi]t; y ≥ 0 satisfying the criterion ||yi||=1. c: the weighted parameter array should be normalised by combining: d: most suitable genomes (p*α) will be identified (where α is an amount specifying a percentage of p that is below one) by calculating the value of fitness of each balanced decoded weighted vector (y) and ranking them based on this value. �⃗⃗� = �̅� √∑ (𝒀𝒊)𝟐 𝑪 𝒊=𝟏 , …(14) e: return the updated solution (p*(1-α)) via the ga’s selection, crossover and mutation processes and set t=t+1. f: combine the recently replicated chromosomes with the most promising parental chromosomes to create an additional batch of genes. g: following the procedures outlined in steps b and c, decipher and standardise the genetic material from the freshly created population. repeat step d to determine every chromosome’s value for fitness, then finish the iteration if t equals the preset value ngener. if not, proceed to e. 4. experimental scenarios to determine the ideal arrangement for ga, numerous tests were executed by systematically altering essential factors. the assessment concentrated on the impact of these setups on detection accuracy and overall performance. the examined factors included mutation rate, population size, bits per variable and crossover rate. the ga method was executed with multiple settings of an identical factor to determine the ideal array of values. the experiments were conducted using matlab®. ahmed a. thabit al-khwarizmi engineering journal, vol. 21, no.4, pp. 8292 (2025) 88 4.1. parameter tuning and experimental setup the parameters utilised for testing are listed in table 2. the best-performing configuration, based on detection probability and convergence speed, is shown in table 3. table 2, testing parameters variable value rate of mutation [0.02, 0.12, 0.17, 0.21, 0.28, 0.31, 0.4] size of population [6, 12, 18, 24, 30] no. bit per variable [2, 4, 8, 16, 32] rate of crossover [0.52, 0.54, 0.62, 0.64, 0.8] table 3, obtained best results variable value rate of mutation 0.12 size of population 30 no. bit per variable 16 rate of crossover 0.64 4.2. simulation results and observations using the optimised parameters, simulations were conducted over 250 generations with population sizes of 35 and 24 sus. the mutation probability, crossover portion and false alarm rate (pf) were set at 0.05, 0.75 and 0.01, respectively. using the best settings determined in the preceding section, the simulation will run the suggested ga approach. the value of fitness determines its identification likelihood, as shown in fig. 7. it is observed how the ga option meets the greatest achievable answer, which is 100%. the subsequent settings were employed by bga as follows: 250 generations to come, 35 population length as minor with 24 sus, 0.05 chance of mutation, 0.75 population for gestation and 0.01 for pf. fig. 7. sample of obtained results in fig. 7, data 1 represents the results of the proposed method, while data 2 is the mean fitness binary. the effect of mutation rate on overall performance is clearly noticed in fig. 8, which shows direct proportionality between the detection rate and the mutation rate. similarly, direct proportionality between the generation number and the fitness function is shown in fig. 9. fig. 8. direct proportionality between the detection and the mutation rate fig. 9. relation between the generation number and the fitness function. 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0.8 0.82 0.84 0.86 0.88 0.9 0.92 0.94 0.96 effect of mutation rate on detection rate mutation rate d e te c ti o n r a te 50 100 150 200 250 300 350 400 450 500 0.8 0.82 0.84 0.86 0.88 0.9 0.92 0.94 0.96 0.98 1 improved fitness progress of ga method number of generations f it n e s s ahmed a. thabit al-khwarizmi engineering journal, vol. 21, no.4, pp. 8292 (2025) 89 fig. 10. energy consumption vs. population the relationship between population size and energy consumption in the proposed ga framework is shown in fig. 10. as the population size increases, the energy consumption exhibits a proportional growth due to the higher number of individuals being processed in each generation. this trend is also linked with the high computational snowball associated with larger populations. thus, there is a trade-off between improving detection performance and minimising energy costs when implementing real-time detection. 5. proposal and other methods: comparative analysis to test the efficiency of the proposed ga-based algorithm, several standard spectrum-sensing techniques were considered for comparison: energy detection (ed), matched filter (mf) and convolutional neural networks (cnns). the evaluation was done under common simulation parameters of 8 mhz bandwidth, 10 ms sensing time duration and 10 dbm primary transmission power. the system was assumed to be under a very harsh noise environment of snr ratios below −15 db. 5.1. detection rate vs. false alarm rate as shown in fig. 11, the proposed ga approach achieved a pd of 90% with a pf of 0.04, outperforming cnns (83%), mf (70%) and ed (58%). this outstanding performance underscores ga’s strength in optimisation and adaptability in the sensing process. fig. 11. comparative analysis of the suggested and traditional methodologies 5.2. roc performance comparison the automated technique provides better detection probability over a wide range of false alarm rates, as seen from the roc curves in fig. 12. this is further evidence of the reliability and robustness of the proposed model under varying operational conditions. for the comparison, we used standard deflection factor (sdf), normal deflection coefficient (ndc), modified deflection coefficient criterion (mdc), maximal ratio combining technique (mrc0 and equal gain combining technique (egc). fig. 12. comparative analysis of the proposal against alternative methods 5.3. bit error rate analysis as shown in fig. 13, the ber of the ga model was markedly least (10⁻⁵). this result further validates the method’s resilience to noise and channel degradation, particularly in low-snr conditions. 5 10 15 20 25 30 1 1.5 2 2.5 3 3.5 4 4.5 population size e n e rg y c o n s u m p ti o n ( a rb it ra ry u n it s ) 0 0.01 0.04 0.07 0.1 0.14 0.16 0.2 0.4 0.8 1 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 false alert d e te c ti o n r a te ed matched filter cnn proposed method 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 probability of false alarm (pf) p ro b a b ili ty o f d e te c ti o n ( p d ) enhanced roc performance comparison of detection methods proposed ga ndc mdc mrc egc hdf(or-rule) ahmed a. thabit al-khwarizmi engineering journal, vol. 21, no.4, pp. 8292 (2025) 90 fig. 13. ber of the proposed system the proposed autonomy sensing method achieved equally or more competitive results than relative traditional techniques, rendering it quite versatile and adaptable to next-generation crns. 6. conclusion a methodology for spectrum sensing and resource allocation in crns through biological algorithms has been proposed in this paper in detail. bga performance was evaluated for different settings and compared with other conventional spectrum-sensing approaches, such as ed, mf and cnns. the results of the simulations demonstrated the advantage of the ga-based system in terms of detection accuracy with minimised false alarm rates along with low noise and channel variations. in this research, we also developed a cooperative sensing model based on the ga, which enhances the performance of the soft-combining fusion scheme in the following ways: (1) fitness-based selection, multipoint crossover and (2) adaptive mutation for optimising the weighting vector for secondary users involved; (3) validation of performance through detailed simulation studies, which showcases improved detection reliability even at low signal-tonoise ratios; and (4) traditional versus deep learning methods are compared, and the performance 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( 2025) 82-92، صفحة 4، العدد21مجلة الخوارزمي الهندسية المجلد احمد عبد الرضا ثابت 92 األداء وتحسين إدارة الطيف في أنظمة االتصاالت باستخدام الخوارزمية الجينية تقييم 4حيدر وهب عليوي، 3علي جابر العسكري ،2بسام حميد عبد ،*1احمد عبد الرضا ثابت ، بغداد، العراق الجامعة التقنية الوسطى الكهربائية، الكلية التقنية الهندسية 1،3 ، بغداد، العراق الجامعة التكنولوجية الكهربائية، قسم الهندسة 2 قسم الهندسة اإللكترونية والكهربائية، جامعة برونيل لندن، المملكة المتحدة 4 ahmed.thabit@mtu.edu.iqالبريد االلكتروني: * المستخلص زدحام ونقص في ظل تزايد تقنيات االتصاالت الالسلكية، مما يزيد من الطلب على طيف الترددات الراديوية المحدود، ويخفف حتى اآلن من حدة مشاكل اال ، القادرة على تحسين دقة الكشف والوصول (bga) الطيف يعتمد على الخوارزمية الجينية الثنائيةاالستخدام والتداخل، تقدم هذه األطروحة نموذًجا حديثًا إلدارة crn الترميز الثنائي لتحديد عوامل الترجيح المثلى للمستخدمين الثانويين في سيناريو bga تتبع .(crns) التكيفي للطيف في شبكات الراديو المعرفية دمين الثانويين نتائج بأداء أسرع بكثير وموثوقية أفضل من األساليب الجينية التقليدية. في مخطط استشعار الطيف التعاوني المقترح، سيُرسل العديد من المستخ على ضبط معامالت الترجيح بدقة عبر آلية دمج القرار الناعم. تتطور الخوارزمية bga االستشعار المحلية الخاصة بهم إلى مركز دمج حيث سيعمل تحسين ينية إلى آخر من خالل تطبيق عمليات االختيار والتقاطع والطفرة الكتشاف أفضل تكوين. أُجريت تجارب محاكاة مكثفة لدراسة آثار المعلمات الج من جيل الُمحسَّن يُمكنه تحقيق احتمالية كشف تصل إلى bga الحرجة الحتمالية الطفرة ومعدل التقاطع وحجم السكان على قدرة الكشف. أظهرت النتائج أن إطار عمل يبلغ 96% إنذارات خاطئة يبلغ 0.1تقريبًا، ومعدل يبلغ حوالي 0.12، ومعدل طفرة بتات إلى ⁵⁻ 10× 7، ومعدل خطأ اإلشارة نسبة تكون حتى عندما ة عند اختبارها مقابل خوارزميات قًا واضًحا للخوارزمية المقترحديسيبل. باإلضافة إلى ذلك، أظهر التقييم المقارن تفو 15-الضوضاء منخفضة للغاية عند ء. كما يؤكد تقليدية مثل كشف الطاقة، والترشيح المتطابق، وااللتواءات القائمة على الشبكات العصبية، وذلك عند تعريضها لظروف صعبة ومعرضة للضوضا ، ويقدم حالً قابالً للتطوير إلدارة الطيف في أنظمة الجيل الخامس cr هذا العمل على إمكانية تطبيق الخوارزميات التطورية في تعزيز الذكاء المعرفي ألجهزة .الحالية وأطر الجيل السادس المستقبلية mailto:ahmed.thabit@mtu.edu.iq _53-65_ kusay h. jabir 53 flutter speed limits of cantilever rectangular and tapered plates kusay h. jabir foundation technical education technical college-baghdad (received 3 april 2007; accepted 9 september 2007) abstract: the aerodynamic and elastic forces may cause an oscillation of the structure such as the high frequency of the airfoil surfaces and the dynamic instability occurring in an aircraft in flight and failure may occur at a speed called flutter speed. in this work, analytical and numerical investigations of flutter limits of thin plates have been carried out. the flutter speed of rectangular plates were obtained and compared with some published results. different design parameters were investigated such as aspect ratio, thickness and their effects on flutter velocity. it was found that the structural mode shape plays an important role in the determination of the flutter speed and the coupling between the bending and torsional mode is the main cause of flutter. key words:flutter, speed, plates. introduction: in mechanics, there are three types of forces aerodynamic, elastic and inertia. the interaction between aeroelasticity and elastic forces is called static aerodynamic such as the divergence problem and the interaction between elastic, aerodynamic and the inertiaforces called the dynamic aero elasticity and the flutter is an example for this phenomena in which the amplitude of the oscillations may diverge causing failure. therefore, this research is concerned with the determination of flutter speed for thin plates which are found in many aeronoutical structures. r.s srinivasan and b.j. baba [2] studied the flutter analysis of cantilevered quadrilateral plates and the problem is solved by using a numerical method involving an integral equation based upon finding the strain and kinetic energies of the plate. e. nissim and i. lottat [3] suggested an optimization method for the determination of the important flutter modes. the method is based on the minimization of the quadratic values derived from the equation of motion. alkhwarizmi engineering journal vol.3 , no.3, pp 53-65 (2007) alkhwarizmi engineering journal kusay h. jabir/al-khwarizmi engineering journal, vol.3, no.3, pp 53 65 (2007) 54 r.s. srinivasan and b.j. baba [4] described the free vibration and flutter of laminated quadrilateral plates. they derived the differential equation required to obtain the flutter speed of simple rectangular plates. m.w. kehoe [5] reviewed the test techniques developed over the last several decades for flight flutter testing of aircraft practical experiences and example test programs were presented to test the effectiveness of the various approaches used. brain danowsky [6] studied the development of an aircraft structural variation model, accounting for variations in structural mode shape as well as structural frequency, which has many advantages for the design of aircraft and aircraft flight control systems. j.hoas, etal [7] described the flutter of circulation control wings and explained the flutter stability of high aspect ratio circulation control wing using lumped approach on conjunction with a modified unsteady aerodynamic strip analysis method. j.e. sedaghat et al [8] developed to predict the speed and frequency at which flutter occur based upon the use of symbolic programming. the approach performs the computation in a single step and does not require the repeated calculations at various speeds required when using the classical v.g. method. t.s talib [9] determined analytically using the damping method and calculated the natural frequencies and mode shapes using the finite element technique for subsonic wing structure. he showed that the flutter speed change with changing the skin thickness, material properties and the altitude. his calculations indicate that structural mode shape variation plays a significant role in the determination of wing flutter limits. in this work, the v.g. method together with developed finite element package will be adopted and the flutter speed will be defined for thin plates with different aspect ratios and thickness for both rectangular and tapered plates. theory: to determine the equation of motion, consider the section shown in fig.1 with two degrees of freedom α and h. [9] the downward displacement of any other point on the airfoil is: [8] z=h±xα the strain energy is composed of two components linear and rotational parts 22 . 2 1 2 1 hkku h+= αα ………………..……(1) and the kinetic energy is: ∫ ∫ ∫++= ]2[ 2 1 222 dxxxdxhdxht ραραρ ... (2) using: ∫ == 22 amrdxxi ρα ∫ == amrxdxs ρα therefore, 22 . 2 1 2 1 αα αihmxmht a ++= using lagrange equation in the form: qq q ut q ut dt d = ∂ −∂− ∂ −∂= )(])([ & ………… (3) where q=q (h,α) inserting equations (1) and (2) into (3) yield the following characteristic equation,         =               +               2 22 2 0 01 mb m mb f b h rw w b h rx x h a a αα ααα && && .. (4) the solution may be assumed as follows: iwtehh 0= and iwte0αα = ……………..…………………(5) equation (4) is reduced to kusay h. jabir/al-khwarizmi engineering journal, vol.3, no.3, pp 53 65 (2007) 55         =               +               2 22 2 2 2 0 01 mb m mb f b h rw wb h xx x w h αα αααα α …. (6) the aerodynamic force and moment are given by [9]: )]) 2 1(([23 nn lall b hwbf +−+= ααπρ where k cilh 121−= 2 221 2 1 k c k cil − + −=α }]) 2 1())( 2 1({ ) 2 1([ 2 24 hh hh l a mlam b hlamwbm + +++−+       +−= αα πρ k imm h 1 8 3, 2 1 −== α then the equation of motion becomes:               +               −= α α αα αα α b h rw w b h rx x wl h h 22 2 2 2 0 0 1 simplifying and using 2 2 2 α η w w= and 2 2 2 αw wr h= with 2b m πρ µ = gives:                   ++++−+− +−ω = αµ αα α b h lamlamam lall l hhh hh h 2 2 ) 2 1())( 2 1() 2 1( ) 2 1( …(7) which can be expressed as a flutter equation in the form:         +ω=         αα b h mab h k ijijij ][][ 2 fig. 1 airfoil restraind from bending and torsional motion in an airstreem by spring kh and kα, acting a distance ba aft of midehord. also shown are lift l and pithing moment my about the axis twist.[9] where [kij] is the stiffness matrix [mij] is the mass matrix and [aij] is the aerodynamic matrix finite element method the plate is analyzed by using a suitable element. the element have 8 degrees of freedom with 5 degrees of freedom of each node (u, v, w, θx and θy in the x, y and z directions) and the rotations about x and y axes respectively. the generic displacements at any point of the middle surface are [10]: ∑ ∑ ∑ = = = = −=−= == = 9 1 9 1 9 1 2 2 },,{}{ i ii i xiix i yiiy wnw nzv nzuand wvu θθ θθ δ ……….……….…….(8) ……………..……….(9) …………………….(10) kusay h. jabir/al-khwarizmi engineering journal, vol.3, no.3, pp 53 65 (2007) 56 { }∈ { }                 + + +=                 ∈ ∈ =∈ zx yz xy y x zx yz xy y x uw wv vu v u ,, ,, ,, , , γ γ γ [ ]{ }δb )9,...2,1( 0 0 22 0 0 2 0 2 00 =                       − − i na nb bhah bh ah b ii ii ii i i i ζζ ζ ζ 2 h ζ ...... 2 biaii bhbb ζ+=                 − −− − =                 − − = i ii i bi ii ii ai n ba b b na nb b 00 000 0 00 000 , 0 0 000 000 000 ηξ ηξ ,22*,12* ,12*,11* nnjb nnja i i += +=           = ξ ηξ ηξ ,00 0,, 0,, ][ z yx yx d ∫ ∫ ∫= ζηξ dddjbdbk te ]][[][][ ηξddjbdbhbdbk b t ba t a e ∫ ∫ += ]][[][ 6 ]][[][2][ 2       = shear bending d d d 0 0 ][       + =             −− 10 01 )1)(2.1(2 ; 2 100 01 01 )1(12 2 3 v ehd v v v v ehd shear bending ηξρ ddjnnhnnm b t ba t a e ) 6 2(][ 2 += ∫ ∫ strain–displacement relationship : the strain matrix is given by : ...........................(11) = and the strain displacement matrix [b] may be written as: ………….…(12) we can isolate terms in bi that multiply by , then and j* is jacobian inverse matrix. ………..(13) formulation of stiffness matrix : the element stiffness matrix [k]e for the element, using b matrix in eq. (12) as follows : …...(14) taking integration through thickness; eq . (14) becomes where {d} is the stress-strain matrix for isotropic material ………………………..(15) the first part of eq (15) is due to transverse shearing deformation where as the second part is associated with flexural deformation. formulation of mass matrix : the formulation of consistent mass matrix for element qpb9 becomes (17) kusay h. jabir/al-khwarizmi engineering journal, vol.3, no.3, pp 53 65 (2007) 57 ninnin ba           −=           = 001 010 100 , 001 000 000 ∫ ∫ ∫ ∂∂= ζηξξ dddjnna te ]][[][][ ∫ ∫ ∫ ∂∂+= ξξ /)()( 2 ]([][ a t ba e nnhna ∫ ∫ ∂∂= ]/[][2(][ ξa t a e nna ajiaij ≠ { } 0])[][][ =−+− qakmk λ λ d bv r o 3 2 2 1 ρλ = )/(422 dtbrwk ssρ= 2w where the first part of eq. (17) consists of translation inertias and the second part gives rotational (or rotary) inertias. formulation of aerodynamic matrix the formulation of aerodynamic matrix for element qpb9 becomes. ζηξηξ dddjnh b ])/[ 2 ∂∂+ ……….(18) for simplicity it is assumed that the air flowing above the panles is parallel to the x-axis as shown in fig. 2 and the effect of any air entrapped below may be neglected . by integrating eq . (18) through the thickness produces. ηξη ddjnnh b t b ]/[][ 2 2 ∂∂+ ………...(19) where fig.2 panal under airfolow. flutter equation and solution method : the flutter equation can be derived as: …………….(20) where k, m and a are matrices of size (m*m) degrees of freedom. here non dimentional dynamic parameter and it is equal to ……………………(21) where pa is air density, v is the free stream velocity, br is the half length of wing at root, d is the flexural rigidity of the plate and, k2 is the eigen value and it is equal to [8] ………….…(22) where is the natural frequency, ρs is the material density and ts is the plate thickness. equation (20) is a standard eigen value problem. the parameters and k are non-dimensional quantities. note that for zero flow velocity and k then represent the square of the non-dimensional natural frequency, so that in this case the eigenvalues are real. as the flow velocity increases from zero, two eigenvalues will usually approach each other and coalesce (become complex conjugates) to kcr at a value of 2 which is the critical value of dynamic pressure. for a large system of equation, it is a relatively difficult task to find the eigen values of equation (12), since in general the matrices involved are complex and asymmetric. therefore, the problem is separated into two parts. first, set zero flow veiocity (w=0) in equation (12) and determine a finite number, say n,of normal modes of the structure ,where n<m and m is the order of the matrix k, m. at this point, the finite element method is used to calculate the modes as accurately as desired by selecting the proper mesh size, and a suitable eigen value technique. use the subspace technique to find the first five modes. second, kusay h. jabir/al-khwarizmi engineering journal, vol.3, no.3, pp 53 65 (2007) 58 after finding the eigen value and eigen vectors then use the normal mode method to represent the eigen vectors (mode shapes) in normal coordinates [4]. results and discussions the results from the finite element program together with the relations between the frequency of the plate and the eigen value at the point of intersection between bending and twisting modes which represents the critical case from which the flutter speed is obtained according to the analytical solution presented in this work. validity of the work the plate shown in fig. 2 is solved by using different f.e meshes (2x2) 128 d.o.f , (3x3) 264 d.o.f , (4x4) 550 d.o.f , (5x5) 488 d.o.f the geometry and material properties are as follows: modulus of elasticity e = 40 gpa poisson's ratio υ =0.25 den sity of the mat erial = 1500 kg/ m3 thickness t = 16 mm width b = 0.5m air density = 0.46 kg /m3 it is found that the first fundamental frequency was 1.683 rad/s. the convergence study is shown in fig. 3. therefore, this mesh is used to analyze the flutter speed. to obtain the flutter speed, two cases are investigated 1) aspect ratio ar = br l 2 where l= 4m , br = 0.5m ar = 4 5.02 4 = x 2) ar= 1.5 the results of the finite element program together with results of the used analytical method, are shown in table 1. table 1: f.e results – natural frequencies of the plate with aspect ratio=1.5 mode freq. (hz) freq. (hz) fem analytical fem analytical 1 1.68 1.75 12.03 13.3 2 10.6 11.01 14.48 15.2 3 13.85 14.5 75.4 76.02 4 32.12 33.05 140.6 142.31 5 43.12 44.30 189.25 190.25 ar = 4 ar = 1.5 kusay h. jabir/al-khwarizmi engineering journal, vol.3, no.3, pp 53 65 (2007) 59 the eigan value λ = 252 from equn (21) and by using fv =33.2 m/s the flutter speed becomes: fw = 5.7 rad/s compared to the results obtained from [3], in which ωf =6.8 rad/s and fv = 34 m/s, therefore, the percentage of discrepancy will be 2.35% which gives a confidence in using the developed finite element program and analytical investigations. tapered plate the tapered plate shown in fig.4 with the following geometry and material properties. steel of modulus of elasticity e= 207 gpa poisson's ratio ν= 0.3 case 1 aspect ratio = ar = 2.1 027.0 )18.0( 2 == a lz and the air properties are: density = 1.2256 kg/m3 at sea leves with sonic speed = 340m/s at 20oc, therefore a = 20.04 t λ critical = 2 2 1 vaρ with mach no. = a v the finite element mesh used for the previous problem was employed her. different thicknesses was used and the corresponding modes were inserted in table 2, as obtained from the finite element program. the corresponding λ cr were obtained from the corresponding mode shapes for each case for both , bending and torsional modes and their point of coupling defines λ cr from which the flutter speed and the flutter frequency. case 2 λ = 1.671.9, ωf =28.628 rad/s and the flutter speed fv =108 rad/s are obtained. four thicknesses were tried 0.5, 1.0, 1.5 and 2 mm as shown in figures 4,5, 6 and 7. it is seen that as the thicknesses is increased λ or is decreased and the flutter velocity is decreased and the flutter frequency is decreased. this is again due to the increasing in the flexibility in reducing the thickness and decreasing the stiffness when the thickness is increased, the stiffness and the mass, both are increased and the flutter speed is decreased. therefore the limits of the flutter speed depend upon material properties and geometry. it can be concluded that increasing the aspect ratio, the flutter speed is increased. this is because the flexibility of the plate is increased when the aspect ratio is increased. table 2: f.e results of the tapered plate kusay h. jabir/al-khwarizmi engineering journal, vol.3, no.3, pp 53 65 (2007) 60 thickness (mm) modes λ cr flutter velocity (m/s) fem v-g method discrc -pancy % mach no. flutter frequency (hz) fem v-g method discrc -pancy % 0.5 14.2 42.8 84.8 137.00 27382.4 668.5 690.6 3.200 1.966 28.2 30.5 7.541 1.0 28.4 85.5 169.7 274.9 135851 472.6 488 3.155 1.39 56.4 58.2 3.092 1.5 42.62 128.24 254.42 410.6 91167.7 385.7 405.6 4.906 1.13 84.2 88.4 4.751 2.0 56.8 170.92 399.1 547.0 68306.4 333.87 345.6 3.394 0.98 112.8 115.3 2.168 case 1 case 2 conclusions 1. for flat plates, the flutter speed is decreased, when the thickness is increased. this is because the stiffness is increased and weight penalty is introduced and a compromise between the required flutter speed limitation and the thickness of the plate. 2. for tapered plate similar conclusion is obtained i.e about 50% flutter speed reduction when using thickness = 2mm instead of using sheet thickness = 0.5 mm 3. the interaction between the finite element and the flutter characteristic is a powerful technique to predict the flutter of the plates. s = 0.00000000 r = 1.00000000 dof w n 100.0 150.0 200.0 250.0 300.0 350.0 400.0 450.0 500.0 550.0 600.0 1.40 1.60 1.80 2.00 2.20 2.40 2.60 2.80 3.00 3.20 fig.3 convergences study of the finite element results sinusoidal fit: wn=a+b x cos(cx+d) kusay h. jabir/al-khwarizmi engineering journal, vol.3, no.3, pp 53 65 (2007) 61 coefficient data: a = 9.2770748 b = 7.5451525 c = 0.0013603357 d = 2.397878 fig.4 tapered cantilever plate. material: steel, ρ=7800 kg/m3, e=210gpa, ν=0.3, ar=180/180=1 air property: ρa=1.2256 kg/m3, sonic speed=340m/s at 20 oc, λcr =1/2 ρa.v2 the results shown in table 2 have an acceptable agreement between the finite element results and the v-c method, with maximum discrepancy increasing thickness from 0.5mm to 2mm gives a reduction in the flutter speed. this is because that increasing the thicknesses given as increasing in the stiffness which decreases the flutter speed. the results are shown in fig. 9. fig.5 the bending and torsional modes for the cantilever tapered plate with thickness 0.5mm. fig.6 the bending and torsional modes for the cantilever tapered plate with thickness 1mm. 180 18 0 (v) air veloci fixed 120 thickness (0.5-2mm) kusay h. jabir/al-khwarizmi engineering journal, vol.3, no.3, pp 53 65 (2007) 62 fig.7 the bending and torsional modes for the cantilever tapered plate with thickness 1.5mm. fig.8 the bending and torsional modes for the cantilever tapered plate with thickness 2mm. 300 350 400 450 500 550 600 650 700 0 1 2 3 thickness (mm) fl ut te r v el oc ity (m /s ) fem v-g fig. 9 references [1] r.s. srinivasan and b.j baba " flutter analysis of cantilerer quadrilateral plates" j. of sound and vilration 98 (1) , 1985. [2] e. nissim and i. lotta an optimization method for the " determination of the important flutter modes : j . of aircraft , vol. 18 , no. 8 , 1981 . [3] r.s. srinivasan and b.j . baba " free vibration and flutter of laminated quadrilateral plates " computers and structures , vol.27 , no. 2 , 1987 . [4] m. w. keho " a historical overview of flight flutter testing" nasa , technical memorandum 4720 , oct 1995. [5] brain danowsky " formulation of a complete aaircraft structural variation model for robust flutter prediction , iowa state university , feb , 2003 [6] j. hoas , david , chapra , inderjit " flutter of circulation control wings david research cneter" , usa , 1989. [7] m. sadeghi, s.yangy, f. liuz, h. m. tsaix parallel computation of wing fiutter with coupled navier-stokes ksd method aiaa 2003. kusay h. jabir/al-khwarizmi engineering journal, vol.3, no.3, pp 53 65 (2007) 63 [8] t. s. talib " flutter speed limits of subsonic wings" . m.sc thesis , university of technology , 2005 . [9] l.raymond bisplinghoff, hoit ashley and l.robert halfman "aerolasticity addision" wesley publishing company, 1957. [10] [11] william weaver "finite elements for structural analysis", printice-holl engleod cliffs, n.j. usa, 1984. kusay h. jabir/al-khwarizmi engineering journal, vol.3, no.3, pp 53 65 (2007) 64 nomenclature symbol meaning units f h m sα t u wα [kij] [mij] [aij] iα kh kα m x z α ρ total force the vertical coordinate of the axis of rotation mass of wing first moment of inertia kinetic energy strain energy up-wash velocity of the airfoil stiffness matrix, mass matrix and aerodynamic matrix second moment of inertia about shear center. stiffness for translation spring stiffness for tensional spring total moment the distance measured from the shear center downward displacement of the airfoil angular displacement for wing air density n m kg kg.m n.m n.m m/s kg.m2 n/m n/m n.m m m rad kg/m3 kusay h. jabir/al-khwarizmi engineering journal, vol.3, no.3, pp 53 65 (2007) 65 حدود سرعة الرفرفة للصفائح المسلوبة و المستطیلة الناتئة قصي حاتم جبر بغدادالكلیة التقنیة/ ھیئة التعلیم التقني :الخالصة یمكن أن تس بب الق وى اإلیرودینامیكی ة والمرن ة تذب ذبا للھیك ل حی ث تول د ت ردد ع الي ألس طح المطی ار تحدث ف ي الط ائرة أثن اء الطی ران والت ي یمك ن أن تس بب إنھی ارًا بس رعة تس مى بس رعة إضافة الى الالإستقراریة التي ت م بح ث . ة الرفرف ة للص فائح المس تطیلة وت م مقارنتھ ا م ع نت ائج منش ورة ـفي ھذا البحث تم إیجاد حدود سرع . الرفرفة د بأن النس ق الھیكل ي یلع ب دورا وج. عدة عناصر تصمیمیة مثل النسبة الباعیة والسمك وتأثیراتھا على سرعة الرفرفة .مھما في إیجاد سرعة الرفرفة والتقارن بین نسق اإلنحناء واإللتواء السبب الرئیس في الرفرفة 1 al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 21, no. 2, june, (2025), pp. 117–135 k-gen phishguard: an ensemble approach for phishing detection with k-means and genetic algorithm ali raheem al-hafiz1*, adnan j. jabir2 and shamala subramaniam3 1, 2 department of computer science, college of science, university of baghdad, baghdad, iraq 3 department of communication technology and networking, faculty of computer science and information technology, universiti putra malaysia, serdang, 43400, selangor darul ehsan, malaysia *corresponding author’s email: aliraheem2201m@sc.ubaghdad.edu.iq (received 17 november 2024; revised 9 march 2025; accepted 20 april 2025; published 1 june 2025) https://doi.org/10.22153/kej.2025.04.011 abstract phishing detection is considered a critical problem in cybersecurity, and utilising machine learning with an efficient feature selection method for precisely identifying malicious websites is deemed the most critical challenge. this research presents a two-phase phishing detection system by employing unsupervised feature selection and supervised classification. in the first phase, the best set of features is identified by the genetic algorithm and is utilised by the kmeans clustering algorithm to divide the dataset into groups with similar traits. in the second phase, the best set of features in each group is identified through the genetic algorithm to enhance the classification process. finally, a voting ensemble technique is applied, in which the support vector machine (svm), random forest (rf), extreme gradient boosting (xgboost) and adaptive boosting (adaboost) models are combined. predictions are aggregated using a soft voting mechanism. this research utilises the web page phishing detection dataset, which consists of 11,430 urls with 87 features. from the results, an accuracy of 99% is achieved using the voting ensemble technique with feature selection compared with 77.3% without feature selection. the model performance experiences a significant boost through the ga-optimised feature selection by reducing computational complexity and improving key metrics such as accuracy, precision and f1-score. additionally, the performance across four clusters demonstrates the positive impact of k-means clustering in improving classification accuracy for specific data groups. as proven by the obtained results, integrating feature selection with ensemble learning is effective for phishing detection; moreover, the scalability and efficiency of such a solution in real-world applications are demonstrated. keywords: adaboost; ensemble learning; feature selection; genetic algorithm; k-means clustering; machine learning; phishing detection 1. introduction phishing is a popular cyber threat, where the attacker tricks the users to disclose sensitive information, including credit card numbers, usernames and passwords. they create fake websites that resemble legitimate ones. the frequency of phishing attacks has seen a dramatic rise with the rapid increase in internet usage, now reaching nearly 1.13 billion websites and 5.3 billion users globally as of october 2023 [1]. the covid19 pandemic doubled down on this surge, cementing the rise of online platforms as a way to work, learn and bank. this shift has been exploited by cybercriminals, using fake emails as phishing tools to create major losses in customer trust, reputational damage to businesses and financial consequences [2, 3]. the term phishing attacks refers to a type of social engineering in which attackers exploit the trust that the natural person has towards the attacker and thus not a technical vulnerability. phishing is especially dangerous because it can bypass the most sophisticated cybersecurity systems. social engineering attacks amounted to $121.22 billion in damages to the u.s. in 2016, mailto:aliraheem2201m@sc.ubaghdad.edu.iq https://doi.org/10.22153/kej.2025.04.011 ali raheem al-hafiz al-khwarizmi engineering journal, vol. 21, no.2, pp. 117-135 (2025) 118 followed by similar impacts globally, as the u.s. department of justice noted [4]. however, phishing url detection in web data is a difficult task because web data are generally unstructured and unpredictable. researchers have adopted feature selection techniques to improve classifier performance by identifying the most influential features to enhance phishing detection. these techniques are critical in reducing model complexity to preserve or upgrade its detection ability [5]. recent works have demonstrated that the effectiveness of principal component analysis (pca) in retaining important patterns of url or html features enhances the performance of machine learning based phishing detector models [6]. high dimensional data with many relevant or redundant features, constitute a major hindrance of traditional machine learning models for phishing detection. it decreases accuracy and detection speed whilst increasing the computational costs. the research therefore proposed a two-phase system for phishing detection, where the first phase contains a hybrid model combining k-means clustering and genetic algorithm to determine the best feature set used for producing highly separated clusters. reducing complexity in datasets by grouping similar data points is achieved through k-means clustering, whilst the ga improved feature selection by identifying the most relevant features using genetic algorithm. in the second stage, a system using a genetic algorithm with a voting ensemble model is proposed which enhances the system’s capacity to differentiate between phishing and legitimate sites, leading to improved detection accuracy and decreased false positives and false negatives. the key contributions of this research include the following: • enhanced feature selection: the combination of genetic algorithm and k-means contributes to determining the best feature set to separate the dataset in different groups. • select classifier: the genetic algorithm was employed to select the classifier in the ensemble learning process based on the performance metrics results. • improved accuracy: by selecting the most critical features, the model increases its ability to accurately detect phishing websites. 2. related work researchers have developed various methods to fight against0 phishing attacks in the ongoing battle. however, web browsers, such as google chrome, microsoft edge and firefox, first used whitelisting and blacklisting method to identify phishing sites whilst allowing legitimate sites and blocking malicious ones [7]. google even took this one step further and offered a blacklist api which acts as a database of unsafe websites and ip addresses, assisting users in verifying urls. however, these early methods had huge drawbacks. they were susceptible to minor url changes and zero day phishing attacks and were prone to creating a high false positive rate [7]. in light of these limitations, other sophisticated techniques started to appear. features such as css files were used to differentiate phishing sites from legitimate ones and serve as a pivotal approach in visual similarity detection [8]. the link guard algorithm [9] enhanced this approach by analysing the visual similarities between target pages and known phishing sites through an image-based matching method. to further improve detection accuracy and address the weaknesses of purely visual methods, researchers began to integrate visual similarity with machine learning techniques [10]. additionally, a line of defense heuristic-based methods have emerged to analyse and determine the legitimacy of different website features. such methods have been categorised as content based, where the content of a website and the host information or url of non-content based ones are examined [11-14]. some notable techniques included phish net [15] in which websites are classified using url heuristics and fsm [7] that monitors web form usage. although these heuristics were less prone to false positives than list-based approaches, they often remained inaccurate and could be challenged by attackers who know the system. the advent of machine learning (ml) significantly transformed phishing detection [16, 17]. ml algorithms trained on datasets that analyse web addresses, site structures and code can automatically detect phishing sites [18]. early ml models, such as artificial neural networks (ann), achieved an accuracy rate of 83.38% [19]. as researchers developed methods to handle larger and more complex datasets, ml model accuracy surged beyond 99% [20]. deep learning (dl) techniques further advanced this field; for instance, a model employing deep neural networks (dnn) and support vector machines (svm) achieved 96% accuracy by training on a dataset with 28 features [21]. another innovative approach combined convolutional neural networks (cnn) and long short-term memory (lstm) networks for rapid ali raheem al-hafiz al-khwarizmi engineering journal, vol. 21, no.2, pp. 117-135 (2025) 119 url-based detection, reaching an accuracy of 97% [22]. nonetheless, hybrid techniques, which combine machine learning with deep learning, have proven to be very successful. to illustrate, the accuracies of up to 97.98% were achieved with random forest (rf) and natural language processing (nlp) with feature selection; in addition, combinations of methods incorporating rf with neural networks (nn) and k-nearest neighbors (knn) showed an accuracy between 97.2% and 97.4%, respectively [23]. furthermore, high accuracies produced by ann and rf coupled approaches were comparable, with accuracies of 96.36%–97.33%. in some advanced models which included classifiers such as rf, svm, generalized linear models (glm) and generalized additive models (gam), accuracy of 98.34% was achieved for a single case. these hybrid methods exemplify the growing effectiveness of machine learning and deep learning in accurately detecting phishing attacks. the machine learning models used for phishing detection have received a recent research deal to apply genetic algorithms (gas) for feature selection and hyper parameter optimisation. gabased feature selection in one study resulted in a more accurate model (95.34% on test set). this research demonstrates the effectiveness of gas as a highly efficient method for selecting features and model performance in ways that are simultaneously simple and expressive [24]. more recently, emerging phishing detection models [25] have also enhanced accuracy with the combined use of feature selection, clustering and classification techniques. another approach combines the components of rough set (rs), stabilitycorrelation (sc) and principal component analysis (pca) for feature selection; then, it fits the data to phishing and non-phishing categories through k-means clustering. the model employed deep learning (dl) and decision tree (dt) algorithms for classification, yielding the following impressive results: the accuracy for the decision tree model was 97.2%, whilst the deep learning model reached 96.88%. the outcomes presented here demonstrate the effectiveness of hybrid methodologies in improving phishing detection over traditional techniques. however, other studies have focused on utilising unsupervised learning for detecting phishing websites; k-means is a widely used unsupervised machine learning algorithm that should be used to detect the webpage of phishing sites [26]. the algorithm clusters the websites into the following two groups: set up to distinguish between the legitimate sri websites and phishing websites based on ‘features’ extracted from the urls of the websites [27]. some features include url length, domain age and ip addresses in url where k-means is suggested to be implemented by researchers for identifying phishing sites. the algorithm can successfully classify the sites between the phishing and the authentic ones, which will help in the detection of the threats. in one research [28], the author designed a model of a k-nearest neighbors algorithm integrated with support vector machine to classify a site as phishing, legitimate or suspicious; the suggested model maintained over 98% accuracy. a major strength of the k-means algorithm in anti-phishing lies in its simplicity, scalability and effectiveness at working with noisy data. recently, ga-based feature selection has been employed to identify optimal subsets of features, reducing the dimensionality and computational workload of models [7]. with this ga-driven method, high accuracy and recall levels were observed across classifiers, such as random forest (92.93% accuracy and 89.05% recall) and xgboost (91.53% accuracy and 87.24% recall). the potential of gas to enhance url-based phishing detection has been demonstrated, contributing to research on evolutionary algorithms for improving cybersecurity accuracy and robustness. 3. background machine learning has many ways to handle data challenges, and no single algorithm will solve every problem. specific task, data involved and the model that best fits the situation determines the choice of algorithm [29]. in this thesis, five well-known machine algorithms, namely support vector machine random forest, adaptive boosting, extreme gradient boosting and ensemble learning algorithms are adopted. 3.1. support vector machine this algorithm belongs to one of the most ubiquitous in the field of machine learning applicable to classification and regression goals. it determines the best hyperplane, which separates the data into different classes or estimates the target variable in the case of regression. the basic concept of svm lies in determining the hyperplane when the distance of the two nearest points belonging to two different classes is at its maximum. this margin is the distance from the ali raheem al-hafiz al-khwarizmi engineering journal, vol. 21, no.2, pp. 117-135 (2025) 120 hyperplane to the closest points from each class in the separated space. svm attempts to search for a hyperplane that can be used to classify the classes whilst providing the maximum margin to gain the best generalisation [30]. for non-linearly separable data, svm has kernel trick in which the data are transformed to random hyperspace to make it easily separable. svm can then attempt to look for a hyperplane which will split the data in question into different classes [31]. 3.2. random forest the random forest algorithm is used for regression and classification tasks. it belongs to the family of ensemble learning methods, which combine multiple models to improve the predictive performance of a single model [24]. in random forest, multiple decision trees are constructed independently, each based on a randomly selected subset of the training data and a random subset of the features. the output of the random forest model is then the average or the majority vote of the outputs of the individual trees [32]. 3.3. adaptive boosting adaptive boosting (adaboost) is a popular machine learning algorithm introduced in 1995 by yoav freund and robert schapiro. it is inspired by the idea of a gambler in horse racing seeking advice from experienced bettors to select the best horse. the primary goal of adaboost is to enhance the performance of multiple ‘weak learners’ by combining them into a single ‘strong learner’ capable of accurate predictions. implementing adaboost is easy, and it can be used on a large variety of problems. it shows high performance, working well with low noise data whilst achieving high accuracy. the algorithm is also flexible, because it can be combined with other weak learners, such as decision trees. it also works well with errors by focusing on misclassified samples and improving the model’s overall accuracy in an iterative manner [33]. 3.4. extreme gradient boosting xgboost is a scalable tree boosting with efficiency and memory resource. it is applicable for regression and classification problems. at each step, it creates a weak learner and adds to the overall model. gradient boosting machines (gbms) are created when the weak learner for each step is the gradient direction of the loss function [34]. 3.5. ensemble learning ensemble learning is a machine learning technique in which the predictions of multiple models, known as ‘base learners’ or ‘weak learners’, are combined to improve overall performance. the underlying principle is that more accurate and robust predictions can be produced by a group of diverse models working together than by any single model. this approach is highly effective in various problem domains, including artificial intelligence, machine learning, pattern recognition and data mining; additionally, it has numerous real-world applications. ensemble learning methods rely on the diversity of base models, where different models may make different errors. by combining them, the weaknesses of individual models can be offset. the predictions of these models are aggregated using techniques such as voting (for classification), averaging (for regression) or weighted combinations [35]. 3.6. feature selection feature selection is a preprocessing technique aimed at identifying a minimal subset of features that effectively capture the relevant properties of a dataset for adequate classification by removing irrelevant and redundant information; it reduces data dimensionality, enhancing the speed and effectiveness of learning algorithms. the goal is to determine a subset that performs as well as or better than the original dataset. features, which can be discrete, continuous or nominal, are categorised as relevant, unnecessary or redundant features that do not directly impact the output and fail to add uniquely to the learning target. irrelevant features can be defined as those without influence on the result, with their values created randomly for each case. redundancy occurs when one feature can take on a role of another [36]. feature selection algorithm primarily aims to identify a subset of features that are both independent and effectively relevant to the learning process. feature selection is classified into three categories: filter, wrapper and embedded techniques [37]. ali raheem al-hafiz al-khwarizmi engineering journal, vol. 21, no.2, pp. 117-135 (2025) 121 3.7. genetic algorithm an optimisation algorithm is based on the principles of natural selection [38]. the algorithm is population based and is implemented in keeping with the principle of natural selection [39]. new populations are generated by using genetic operators across generations on current individuals within the population. the parts of ga include initialisation, fitness function, selection, crossover, mutation, replacement and termination [40]. 3.7.1. initialisation initialisation produces a starting population of chromosomes or possible solutions. a possible set of characteristics for phishing website detection is represented by each chromosome. 3.7.2. fitness function fitness function refers to a measure that evaluates the quality or ‘fitness’ of solutions within a given space, determining how effectively they address the problem. it assigns a fitness score based on the solution’s ability to meet the problem’s objectives, guiding the evolutionary process. solutions with higher fitness scores tend to be selected for reproduction and carried forward to subsequent generations [41]. 3.7.3. selection selection is a crucial phase of genetic algorithms because it defines which strings will be involved in reproduction. it is also known as the reproduction operator. selection pressure influences the convergence rate of ga. some of the methods used are roulette wheel, rank, tournament, boltzmann and stochastic universal sampling [42]. 3.7.4. crossover operators are utilised to generate children by using the genetic data of two or more parents. the frequently used crossover operators are single-point crossover, two-point crossover, k-point crossover and uniform crossover. some common types of crossover techniques used in genetic algorithms include partially matched crossover, order crossover, precedence-preserving crossover, shuffle crossover, reduced surrogate crossover and cycle crossover [43]. 3.7.5. mutation in genetic algorithms, mutation is a key genetic operator used to maintain genetic diversity from one generation to the next. it introduces small, random changes to individual solutions (chromosomes) in the population. this step helps the algorithm avoid premature convergence to suboptimal solutions by exploring new areas in the search space [42]. 3.7.6. replacement replacement is the process of changing the old one with new offspring population. when the population has been updated, the cycle is repeated now [42]. 3.7.7. termination termination is a process of continuing to select, crossover and mute these sets until the convergence requirements (e.g., to achieve a particular fitness level or for a fixed number of generations) are satisfied [43]. 3.8. k-means k-means is one amongst the simplest unsupervised learning algorithms used to solve clustering problems. the procedure here involves an easy and simple process of factoring a given dataset through a certain number of clusters. the concept is to determine k centres, in which one is found for each cluster of the dataset. these centres should be placed cunningly because a different location brings a different outcome. thus, individually keeping the frequency as much as possible at a distance from others is a wise move [44]. 3.8.1. elbow method the earliest approach that has ever existed is commonly referred to as the elbow method. it operates by evaluating the value or percentage of a tested variable k and establishing an elbow at a specific point. the value of k in a combination of elbows with k-means represents a graph displaying cluster relationships with reducing errors. increasing the k value causes the graph to decrease slowly until the k value is stable [25]. this method works by evaluating the withincluster sum of squares (wcss) for different values of k. ali raheem al-hafiz al-khwarizmi engineering journal, vol. 21, no.2, pp. 117-135 (2025) 122 ( ) 1 k j xi cj wcss k xi nj =  = − , …(1) 3.8.2. silhouette silhouette is a metric used to evaluate the quality of clustering within a dataset. it quantifies the degree of similarity between a data point and its own cluster (cohesion) as opposed to other clusters (separation). this metric can be used to decide on the number of clusters that should be formed [45]. the silhouette formula is ( ) ( ) ( ) ( ) ( )( )max , b i a i s i a i b i − = , …(2) 4. proposed model a new hybrid approach is used in the proposed model to detect phishing websites. unsupervised and supervised learning techniques are combined to add accuracy and efficiency to the process. by combining k-means clustering with a ga, feature selection is optimised, which is considered a critical component in improving the performance of machine learning classification models. this hybrid method allows for a refined analysis of website features, with redundancy reduced and the dataset partitioned into parts based on similarity. in addition, the best feature set is selected for each resulting cluster through the ga algorithm to enhance classifier performance, thereby enabling the voting model to better differentiate between phishing and legitimate sites. the section below displays a detailed breakdown of the model’s workflow represented in three distinct phases, as shown in fig. 1. in phase 1, the process is initiated with the loading and preprocessing of the dataset to ensure preparedness for analysis. from this step, an initial population of feature subsets is generated. these feature subsets are subjected to unsupervised learning, and k-means clustering is applied to group dataset samples based on similarity using a chosen feature subset. the quality of the clustering is evaluated using the silhouette fitness function, allowing the performance of each feature subset to be gauged. genetic algorithm (ga) operations— selection, crossover and mutation—are utilised to enhance the feature selection process by evolving the population over multiple iterations. this phase is concluded with the identification of the best feature subsets and cluster centres, thus setting the stage for the subsequent phase. phase 2 incorporates supervised learning into the process. the dataset is divided into clusters around the centres and selected features based on the results obtained from phase 1. an advantage of clustering is that for each cluster, a classification model is created by using advanced machine learning algorithms, such as svm, adaboost, random forest or xgboost. the feature subset is iteratively refined by the ga, with the best-performing features selected using genetic operations and repeated looping. the models are then assessed on the basis of their accuracy, precision and f1 scores to ensure that only the most effective feature sets and models are selected. this phase concludes with another round of inspection through the system to strengthen the classification model for each cluster, thereby enhancing its ability to detect phishing threats. phase 3 prepares the last phase of the system for actual application in the real world. the dataset is preprocessed once again, and each sample is assigned to its appropriate cluster. predictions are made by the trained models for corresponding clusters using the selected features. for robustness, an ensemble method was adopted, whereby the final decision was synthesised through a voting mechanism that incorporated the output of several models. the accuracy and reliability of the system are increased by this collective decision-making approach, thereby mitigating the presence of phishing websites in real time. algorithm 1 demonstrates these three phases. algorithm i: k-genphishguard input: dataset d output: final fishing detection ensemble models begin: 1. preprocessing duplicated sample removal. null and constant sample removal. normalisation. class label encoding. 2. genkmeans: the ga is utilised to determine the best features for k-means clustering. the output comprises cluster centres and best feature subset. 4. genclassification: the ga is utilised to determine the best features to train the ensemble set of classifiers for each cluster. the output is the final fishing detection ensemble models for each cluster. end ali raheem al-hafiz al-khwarizmi engineering journal, vol. 21, no.2, pp. 117-135 (2025) 123 the first phase deals with the data preprocessing process, where the dataset is loaded, labels are encoded into numerical format and features are scaled using minmaxscaler to ensure consistent ranges across all features. the data are then prepared for the next phase. the second phase, namely genkmeans, integrates the ga with kmeans clustering to determine the best features that achieve the minimum silhouette score. the strength of k-means clustering is leveraged in identifying natural groupings within the data, and the ga’s ability to evolve feature subsets is utilised to refine the model’s accuracy over multiple iterations. by combining these techniques, an efficient and precise feature selection process is ensured, ultimately enhancing the performance of the phishing detection system. algorithm 2 shows the main steps of this phase. fig. 1. proposed k-gen phishguard model 124 ali raheem al-hafiz al-khwarizmi engineering journal, vol. 21, no.2, pp. 117-135 (2025) as shown in the genkmeans, the initial binary population is generated, where each vector is represented by the selected features. each binary value within the vector is used to indicate whether a particular feature is included in the model (1) or excluded (0). the starting point for the ga is served by this population. the process is then moved to k-means clustering, with the latter performed on the basis of the selected features in each solution of the ga population. the silhouette score is used here as the fitness function, which measures how well each data point is clustered on the basis of its cohesion within its own cluster and its separation from other clusters. the ga proceeds with multiple generations of feature selection, using selection, crossover and mutation to evolve the population. the goal is to maximise the silhouette score by determining the optimal subset of features that enhances clustering performance. once the ga has converged, the bestperforming chromosome, representing the optimal set of features, is selected. in addition, the cluster centres are saved for use in the next phase. the output of the previous phase, i.e., the cluster centres and the best feature subset, is taken as input for the third phase. then, for each cluster, the best feature subset, which achieves the best classification accuracy, is identified using the ga. algorithm 3 shows the detailed steps of this phase. algorithm 3: genclassification input: • cluster centres c = {c0, c1,...ck}. • clustering features f = {f0, f1,...fm} output: • classification feature vectors cf = {cf0, cf1,...cfm}. • trained classification models. begin 1. for each cluster, do 2–6. 2. generate initial population p = {ch1, ch2..., chp}, where each chromosome is a binary vector which represents the selected features. 2. without stopping the condition, do 3–5. 3. for all solutions in (p) = {ch1...chp}, do 4–5. 4. fitness evaluation: • train ensemble classifiers (svm, rf, xgboost and adaboost) using the selected features represented by ch (i). • evaluate performance using metrics such as accuracy, precision and f1 score using the voting method. 5. (ga) for optimisation: selection, crossover and mutation operators. 6. output: the best feature subset cfbest. the trained ensemble classification models. end as shown in algorithm 3, all clusters are iterated upon in step (1), whilst corresponding with the initialisation stage in step (2), where a population of binary chromosomes is created during the initial population generation step. each possible feature subset is represented by a chromosome, and a binary value is assigned to each feature: (1) if the feature is selected; otherwise, (0). step (3) iterates all ga solutions whilst performing the fitness evaluation using a voting method in step (4). for each chromosome, the subset of selected features is used to train the ensemble set of classifiers, which is formed by combining svm, rf, xgboost and adaboost. the classifier’s performance is evaluated using key metrics such as accuracy, precision and the f1 score. these metrics are used as the fitness function to determine the quality of the feature subset. step (5) optimises feature selection by the ga through the following three main operations: selection, crossover and mutation. in the selection process, chromosomes are chosen on the basis of their fitness scores using the roulette wheel method. diversity is introduced by crossover and algorithm 2: genkmeans input: pre-processed dataset (dp). the number of clusters (k) obtained using the elbow method. output: • best feature subset fbest {f1, f2..., fm} • cluster centres = {c1, c2..., ck} begin: 1. generate initial population p = {ch1, ch2..., chp}, where each chromosome is a binary vector representing the selected features. 2. without stopping the condition, do steps 3–4. 3. for all solutions in (p) = {ch1…chp} do perform k-means clustering using ch(i). use silhouette score as the fitness function: ( ) ( ) ( ) ( )( )1 1 max , n i b i a i s n a i b i= − =  . 4. perform selection, crossover and mutation. 5. save the best features f = {f0, f1,...fm} and the cluster centres c = {c1, c2,...ck}. 5. end ali raheem al-hafiz al-khwarizmi engineering journal, vol. 21, no.2, pp. 117-135 (2025) 125 mutation, allowing the algorithm to explore new feature combinations. the population is updated at each iteration, and the best chromosome is retained on the basis of fitness. finally, the output step obtains the best feature subset and the trained ensemble models (based on the best feature selection). this step ensures that the optimal combination of features and classifiers is used for future predictions. 5. dataset this study uses a dataset with 11,430 urls and 87 features extracted for phishing detection. these features are categorised into the following three primary groups: content features (24), url structure and syntax features (56) and external service features (7). the url structure and syntax features capture the patterns of the construction of the urls to identify phishing attempts. the model is trained on webpages associated with urls. additionally, content features are produced, which can be used to assess if phishing activity is indicated by the content. the classification process is extended to include external service features from third-party sources, such as reputation scores. to clearly understand the results of the classifiers, the dataset and its components must first be comprehended. therefore, a detailed summary study of the components of the dataset and their respective proportions was conducted. the dataset is balanced, with 50% phishing urls and 50% legitimate urls, ensuring that one class is not favoured over the others, as shown in fig. 2. this balance is critical for unbiased classification results. the dataset, sourced from kaggle [46], is widely recognised as a standard benchmark for phishing detection, rendering it suitable for reproducibility and comparison across studies. fig. 2. dataset class distribution for phishing 6. metrics and results 6.1. metrics the proposed work evaluates the performance of the phishing detection classifiers to ensure that accurate identification of phishing websites is achieved whilst minimising errors. several metrics have been utilised to assess different aspects of model effectiveness, especially in handling the balanced dataset of phishing and legitimate urls. these metrics include accuracy (acc), which is used to measure the model’s overall correctness; precision (p), which focuses on the accuracy of phishing predictions; and the f1 score (f1), which is used to provide a balance between precision and recall for measuring the model’s effectiveness in detecting phishing sites. these metrics are formulated in eqs. (1–3), respectively. tp tn acc tp fp fn tn + = + + + , …(3) tp p tp fp = + , …(4) 1 2 r p f score r p  − =  + , …(5) where r is the recall function and can be expressed as tp r tp fn = + , …(6) 6.2. result the results presented in this paper are discussed with two scenarios. the first scenario is focused on examining three different cases within the same proposed model to demonstrate the impact of feature selection through the genetic algorithm (ga). this selection process enhances the accuracy of phishing detection by combining ensemble learning with the genetic algorithm. the second scenario involves comparing the proposed model in its various configurations with recent studies on phishing detection. this comparison highlights the effectiveness and advancements achieved by the proposed model. scenario #1 : in this scenario, a step-by-step comparison was carried out to measure the performance of various classifiers individually. these results were then benchmarked against the k-gen model, which incorporates clustering and genetic-based feature ali raheem al-hafiz al-khwarizmi engineering journal, vol. 21, no.2, pp. 117-135 (2025) 126 selection. subsequently, the final model, namely kgen phishguard, was compared with all earlier versions to assess its overall effectiveness. • case 1: comparison between manual classifiers and classifier with ga the performances of classifiers, as demonstrated in table 1, are shown to be significantly enhanced when genetic algorithm (ga) is utilised for feature selection. a marked improvement in accuracy, precision and f1-score is observed across most classifiers. by automating the selection of the most important features, dimensionality is reduced and the learning process simplified. without the application of ga, classifiers process the entire dataset, which results in lower performance metrics. however, with ga, more effective feature combinations are obtained, leading to improved classification outcomes without overfitting. for the svm classifier, accuracy increased from 0.9466 to 0.9500, with precision and f1-score improving from 0.9492 to 0.9514, and 0.9458 to 0.9512, respectively. a remarkable enhancement is observed for the random forest classifier, where accuracy rises from 0.9466 to 0.9755, and precision and f1-score improve from 0.9492 to 0.9755 and 0.9458 to 0.9754, respectively. this improvement is attributed to ga’s ability to optimise ensemble learning. similarly, adaboost shows improved performance, with accuracy increasing from 0.9536 to 0.9597, and precision and f1-score rising from 0.9531 to 0.9598 and 0.9531 to 0.9597, respectively. xgboost also demonstrates enhanced metrics, with accuracy improving from 0.9733 to 0.9770, and precision and f1-score increasing from 0.9742 to 0.9769 and 0.9729 to 0.9769, respectively. these results underscore the critical role of ga in optimising feature selection, significantly enhancing the accuracy, precision and f1-scores of various classifiers, rendering it an effective method for improving classification performance—particularly for large datasets with many features. from fig. 2, applying the classifiers to highquality and balanced datasets can be concluded to yield acceptable values of accuracy, precision and f1-score. however, in fig. 3, all metrics are observed to have increased, especially for the svm and random forest classifiers. a substantial improvement is gained by the svm classifier, whilst even higher accuracy enhancement is achieved by the random forest classifier through the application of an ensemble learning technique. in the latter, multiple decision trees are constructed to improve decision-making performance. table 1, comparisons between classifiers before and after using (ga) without using genetic algorithm using genetic algorithm for feature selection classifier acc p f1 classifier acc p f1 svm 94.6% 94.9% 94.5% svm 95.1% 95.1% 95.1% random forest 94.6% 94.9% 94.5% random forest 97.5% 97.5% 97.5% adaboost 95.3% 95.3% 95.3% adaboost 96.0% 96.0% 96.0% xgboost 97.3% 97.4% 97.2% xgboost 97.7% 97.7% 97.7% fig. 3. classifier results without using ga fig. 4. classifier results using ga ali raheem al-hafiz al-khwarizmi engineering journal, vol. 21, no.2, pp. 117-135 (2025) 127 • case 2: comparison between classifier clusters using the k-gen model to further optimise and enhance the phishing detection model, additional steps were introduced to ensure greater robustness and accuracy. one key advancement in the approach was the incorporation of k-means clustering into the feature selection process. k-means, an unsupervised learning algorithm, played a vital role in classifying and grouping similar data points based on their underlying characteristics. by leveraging k-means, the complexity of the dataset was reduced by clustering similar url features. this step not only helps in minimising redundant information but also assists in identifying meaningful patterns that differentiate phishing websites from legitimate ones. figs. (5–8) illustrate the clustering process and its impact on feature selection and classification. accordingly, it ensures that the subsequent classification models operate more efficiently, focusing on the most relevant features, leading to enhanced performance in phishing detection. the use of k-means is significantly contributed to building a more accurate and robust model, as shown in table 2. the high performance of the proposed model, as demonstrated by the results presented in table 4, is attributed to the effective use of k-means clustering. in this model, the optimal number of clusters (k) was determined to be 4, which was identified using the within-cluster sum of squares (wcss) method. wcss was used to evaluate the compactness of clusters by minimising intra-cluster variance, ensuring that similar data points were grouped closely together. to further confirm this optimal choice of k, the elbow method was applied, and the wcss was plotted against varying k values. the ‘elbow’ point, where the curve begins to flatten, was used to indicate the most appropriate number of clusters, which in this case was found to be 4. this separation of clusters is shown to enhance the model’s ability to isolate distinct patterns in phishing and legitimate websites, thereby boosting classification accuracy and leading to the strong metrics that were achieved. xgboost is seen to perform the best overall and tops the accuracy (97.69), precision (97.6) and f1 score (97.69) amongst the classifiers, especially in cluster 1. such exceptional performance is due to the fact that the clustering process is capable of effectively grouping its data points, thus allowing xgboost to optimise its decision-making process. the high performance of the proposed model, as demonstrated by the results presented in table 4, is attributed to the effective use of k-means clustering. in this model, the optimal number of clusters (k) was determined to be 4, which was identified using the within-cluster sum of squares (wcss) method. wcss was used to evaluate the compactness of clusters by minimising intra-cluster variance, ensuring that similar data points were grouped closely together. to further confirm this optimal choice of k, the elbow method was applied, and the wcss was plotted against varying k values. the ‘elbow’ point, where the curve begins to flatten, was used to indicate the most appropriate number of clusters, which in this case was found to be 4. table 2, comparative analysis for each classifier with k-means clustering classifiers cluster-no acc p f1 random forest 1 97.5% 97.5% 97.5% 2 95.9% 95.9% 95.9% 3 95.9% 95.9% 95.8% 4 95.5% 95.5% 95.4% svm 1 95.1% 95.1% 95.1% 2 93.2% 93.3% 93.1% 3 94.0% 94.0% 94.0% 4 93.4% 93.3% 93.4% adboost 1 95.9% 95.9% 95.9% 2 95.1% 95.2% 95.1% 3 96.0% 96.0% 96.0% 4 94.8% 94.7% 94.7% xgboost 1 97.6% 97.6% 97.6% 2 95.9% 95.9% 95.9% 3 96.0% 96.0% 96.0% 4 95.5% 95.4% 95.4% ali raheem al-hafiz al-khwarizmi engineering journal, vol. 21, no.2, pp. 117-135 (2025) 128 this separation of clusters is shown to enhance the model’s ability to isolate distinct patterns in phishing and legitimate websites, thereby boosting classification accuracy and leading to the strong metrics that were achieved. xgboost is seen to perform the best overall and tops the accuracy (97.6), precision (97.69) and f1 score (97.6) amongst the classifiers, especially in cluster 1. such exceptional performance is due to the fact that the clustering process is capable of effectively grouping its data points, thus allowing xgboost to optimise its decision-making process. similarly, the random forest classifier produces strong results. in cluster 1, the accuracy is 97.5 with the precision and f1 score at 97.55 and 97.5, respectively. in addition, random forest, as an ensemble learning type of learning, together with the feature selection achieved by k-means, is responsible for this robust performance. however, its performance somewhat decreases in the following clusters, with the lowest metrics of cluster 4. notably, the k-gen model, which combines the k-means clustering approach with feature selection, has played a critical role in enhancing the classification results for all classifiers. by segmenting the data into meaningful clusters and selecting the most relevant features, the classifiers successfully focused on the most impactful attributes, resulting in improved performance metrics. • case 3: comparison between voting with ga and voting without the k-gen model in the final case, the phishing detection model was enhanced by incorporating a voting method within an ensemble learning framework, combined with a genetic algorithm, to create a robust detection system. the results were compared to the same model without the use of the genetic algorithm, as presented in table 3. fig. 5. svm evaluation with clustering fig. 6. adaboost evaluation with clustering fig. 7. random forest evaluation with clustering fig. 8. xgboost evaluation with clustering ali raheem al-hafiz al-khwarizmi engineering journal, vol. 21, no.2, pp. 117-135 (2025) 129 the comparison presented in table 3 may be initially perceived as unfair by researchers, as the first model was applied to aggregated data based on similarity and relevant features, whereas the second model was applied to unaggregated data without considering similarity. therefore, this comparison primarily aims to evaluate the same model on the same dataset but without utilising methods for selecting influential features or choosing an appropriate classifier. the results are assessed, as illustrated in figs. 9 and 10. a highly accurate phishing detection model that avoids bias towards false positives and effectively distinguishes between phishing and legitimate websites was achieved by implementing a key development step by utilising voting ensemble learning to strategically combine the strengths of diverse classifiers, such as random forest, svm, xgboost and adboost, thereby enhancing overall accuracy and resilience by aggregating predictions and mitigating the biases and limitations of individual algorithms. therefore, a genetic algorithm is used again but this time to select the classifier, depending on the metrics result of that classifier. a key point that many researchers ask, is the ratio used to split the dataset. the first model used k = 5-fold cross validation, where the training set was partitioned into 5 subsets and used as follows: one subset as test set and the other subsets as train set. by using this method, the model is evaluated over the different data splits which help in adding robustness to the model (resistant to computational artifacts) and less biased in terms of performance evaluation. by contrast, the second model employed a 70:i split 30, where 70% of the data are used for training and 30% for testing. this simple split clearly separates the training from the evaluation phases whilst allowing performance of the model to be tested on data that are entirely unseen. the large difference in performance is shown in the table when the voting model with k-gen is used versus without k-gen. after k-gen is applied, high metrics are achieved for all clusters, with accuracy, precision and f1 score constantly being above 98%. all metrics in cluster 1 are attained at 99% performance. in comparison, the voting model without k-gen results in an accuracy of 77.3%, precision of 82.1% and f1 score of 76%. table 3, comparison of the voting model with and without k-gen model cluster-no accuracy precision f1-score voting with k-gen 1 99% 99% 99% 2 98.6% 98.6% 98% 3 98.9% 98.9% 98% 4 98.5% 98.5% 98% voting without k-gen n/a 77.3% 82.1% 76% fig. 9. voting with k-gen model fig. 10. voting without k-gen model ali raheem al-hafiz al-khwarizmi engineering journal, vol. 21, no.2, pp. 117-135 (2025) 130 the variation in these results is attributed primarily to the fact that the genetic algorithm (ga) was applied twice in the proposed model, a practice that has not been commonly observed in most studies addressing phishing detection. in the first instance, ga was utilised to search for the optimal or near-optimal solution by identifying the most impactful features that assist the classifier, even if its classification performance was initially suboptimal. in the second instance, ga was employed to select the most effective classifier for the classification process during the ensemble classification phase. this dual application of ga has contributed significantly to the superior results achieved in the proposed model. scenario #2: in this scenario, the performance of the proposed model is compared to studies that utilise the same dataset. the performance of the model is structured into different cases, wherein a particular attribute of the model’s performance is considered in each case and its benefits explained. the first case focuses on assessing the effectiveness of the proposed model under identical dataset conditions, emphasising key performance metrics. • case 1: to justify the performance of the proposed phishing detection method, it is compared with studies that utilise the same dataset. [47] the study focuses on establishing reproducible benchmarks for phishing detection using a dataset of 11,430 samples with 87 features spanning url characteristics, web page content and external service data. the authors employed feature selection methods, namely filter and wrapper methods, for identifying significant improvements in model performance when using filter-based incremental feature ranking. amongst the classifiers evaluated, random forest achieved the highest accuracy of 96.83%, surpassing other models such as svm, knn and logistic regression. the study underscores the importance of feature selection in enhancing detection accuracy whilst reducing computational overhead, providing a robust framework for comparing phishing detection methodologies, as shown in table 4. table 4 presents a comparison on the same dataset, with an identical number of samples and features but different feature selection methods applied. the referenced study employed the chisquare method to select features and improve the classifier’s performance in phishing detection. the results were satisfactory, utilising two evaluation metrics, namely accuracy and f1-score. amongst the tested classifiers, the random forest algorithm achieved the highest performance in this experiment. this comparison primarily aims to demonstrate the efficiency of the genetic algorithm in feature selection, as it significantly outperformed the chisquare method. notably, the proposed model is in its initial development stage, focusing solely on the genetic algorithm for feature selection without incorporating k-means clustering or ensemble learning techniques. • case 2: this study [15] utilised the same proposed dataset and was divided and processed using the 10-fold cross-validation method. this approach enhanced the model’s efficiency and robustness. subsequently, the recursive feature elimination (rfe) technique was employed to identify the most representative subset of features for the dataset. rfe iteratively removed the least significant features based on model performance until the optimal feature set was achieved. table 4, comparison of feature selection methods across classifiers ref. feature selection method classifiers accuracy f1-score [47] chi-square dt 94.13% 94.10% rf 96.83% 96.60% lr 94.48% 94.50% nv 79.80% 79.80% svm 73.95% 72.10% proposed model genetic algorithm rf 97.55% 97.54% xgboost 97.70% 97.69% svm 95.11% 95.12% adaboost 95.97% 95.97% ali raheem al-hafiz al-khwarizmi engineering journal, vol. 21, no.2, pp. 117-135 (2025) 131 once the feature selection process was completed, the refined data were fed into the classifiers, including support vector machines (svm), random forest (rf), xgboost (xgb) and adaboost (ada). the results were then compared using evaluation metrics such as accuracy, f1-score and precision to determine the performance of the proposed framework, as shown in table 5. in the table above, the comparison primarily relies on feature selection methods, despite the similarity in the datasets and classifiers used. however, the highest accuracy, f1-score and precision were achieved by the xgb classifier. nonetheless, all classifiers in the proposed phishing detection model notably outperform the results in terms of accuracy, f1-score and precision. • case 3: this study [47] used datasets from different repositories, and a sophisticated stacking ensemble classifier was proposed as the model. the proposed model was compared with its final enhancement, namely k-gen phish guard. table 6 compares with two different models that utilise the same dataset, (dataset-4) consisting of 11, 430 samples and 87 features. in the first model, a sophisticated framework, a combination of feature selection methods, greedy algorithms, cross-validation and deep learning techniques were used to build a stacking ensemble classifier. the highest performance was achieved on dataset-4, with an accuracy of 98.20%. in the second proposed model (k-gen phish guard), genetic algorithms were used once again—this time to select the best-performing classifiers in combination with soft voting ensemble learning. this model demonstrated high efficiency and performance, achieving 99% in accuracy, f1score and precision across most clusters and outperforming the first model in nearly all aspects. table 5, comparison between rfe and ga across classifiers ref feature selection classifiers acc p f1 [15 ] rfe svm 95.9% 96.2% 95.8% rf 96.6% 96.8% 96.6% adaboost 94.6% 94.9% 94.6% xgboost 97.0% 96.9% 97.0% proposed model ga rf 97.5% 97.5% 97.5% xgboost 97.7% 97.6% 97.6% svm 95.1% 95.1% 95.1% adaboost 95.9% 95.9% 95.9% table 6, comparison of ‘a sophisticated framework’ and ‘k-gen phish guard’ across datasets and clusters ref mode dataset/classifier clusterno acc p f1 [48 ] single and hybridensemble learning-based phishing website detection dataset4/stacking 98.20% 94.85% 94.45% proposed model (k-gen phish guard) dataset-4/voting 1 99% 99% 99% 2 98.6% 98.6% 98% 3 98.9% 98.9% 98% 4 98.5% 98.5% 98% 7. conclusion an effective and powerful approach for detecting phishing sites through two scenario comparisons were presented. in the first comparisons, the classifiers were evaluated before and after the genetic algorithm was used. remarkable progress in the accuracy and efficiency of the model in detecting phishing was observed, which was referred to as the first developmental stage. subsequently, the second developmental stage involved integrating unsupervised learning, specifically k-means, with the genetic algorithm to divide the dataset into clusters. within each cluster, a set of influential attributes specific to that cluster was identified to facilitate and enhance the speed and efficiency of the classifier in detecting phishing. this improvement was evident in most clusters, with advancements in accuracy, f1-score and precision compared with classifiers ali raheem al-hafiz al-khwarizmi engineering journal, vol. 21, no.2, pp. 117-135 (2025) 132 that only used the genetic algorithm without kmeans.this model was named k-gen. the third developmental stage introduced the proposed model, namely k-gen phish guard, which outperformed all benchmark models. it achieved an accuracy rate of 99%, demonstrating superior performance compared with all previous models. a second comparison was made between the proposed k-gen phish guard model and recent studies on phishing site detection that used different feature selection methods and classifiers but were based on the same dataset. the proposed model consistently outperformed all models mentioned in the earlier studies. in the model, the dataset was divided into a 7:3 ratio, with 70% allocated for training and 30% for testing, ensuring a robust evaluation process. this approach demonstrated a stronger ability to detect phishing whilst providing a scalable solution to various real-world cybersecurity challenges. in the future, this model could be applied to other types of cyber 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[48] k. adane, b. beyene, and m. abebe, "single and hybrid-ensemble learning-based phishing website detection: examining impacts of varied nature datasets and informative feature selection technique," digital threats: research and practice, vol. 4, no. 3, pp. 1-27, 2023. https://www.kaggle.com/datasets/shashwatwork/web-page-phishing-detection-dataset https://www.kaggle.com/datasets/shashwatwork/web-page-phishing-detection-dataset ( 2025) 117-135، صفحة 2، العدد21مجلة الخوارزمي الهندسية المجلد الحافظ علي رحيم 135 k-gen phishguard والخوارزمية الجينية k-means نهج متكامل للكشف عن التصيد االحتيالي باستخدام 3شمالة سوبرامانيام، 2عدنان جمعه جابر، * 1 علي رحيم الحافظ قسم علوم الحاسبات، كلية العلوم، جامعة بغداد، بغداد ، العراق 2،1 ، 43400قسم تكنولوجيا االتصاالت والشبكات، كلية علوم الحاسوب وتكنولوجيا المعلومات، جامعة بوترا ماليزيا، سيردانج، 3 سيالنجور دار اإلحسان، ماليزيا aliraheem2201m@sc.ubaghdad.edu.iq :البريد االلكتروني * المستخلص يار الميزات الكشف عن التصيد االحتيالي هو مشكلة حرجة في مجال األمن السيبراني، وأكبر تحٍد هو كيفية استخدام التعلم اآللي مع طريقة فعالة الخت اختي استخدام فيهما يتم رئيسيتين، مرحلتين من يتكون االحتيالي التصيد عن للكشف نظاًما البحث هذا يقدم بدقة. الضارة المواقع غير لتحديد الميزات ار لتحديد أفضل مجموعة من الميزات التي يتم استخدامها بواسطة (ga) المراقب والتصنيف المراقب.في المرحلة األولى، تُستخدم خوارزمية التحسين الجيني خوارزمية التحسين الجيني ية، فيتم استخدام لتقسيم مجموعة البيانات إلى مجموعات تحمل سمات متشابهة.أما في المرحلة الثان k-meansخوارزمية التجميع (ga) مرة أخرى لتحديد أفضل مجموعة ميزات داخل كل مجموعة، مما يعزز عملية التصنيف. في النهاية، يتم تطبيق تقنية التجميع بالتصويتvoting ensemble) نماذج دمج يتم آلية adaboost)و xgboostو random forest (rf)و support vector machine (svm)، حيث باستخدام البحث، تحتوي على في هذا الويب التصيد االحتيالي لصفحات بالكشف عن بيانات خاصة التنبؤات.تم استخدام مجموعة 11,430تصويت ناعمة لتجميع دون استخدام %77.3ـ عند استخدام اختيار الميزات، مقارنة ب %99ميزة.أظهرت النتائج أن تقنية التجميع بالتصويت تحقق دقة تصل إلى 87و urlعنوان خوارزمية باستخدام الُمحسَّن الميزات اختيار يُظهر الميزات. وتحسين (ga)اختيار الحسابي التعقيد تقليل خالل من النموذج، أداء في كبيًرا تحسينًا ( الدقة مثل الرئيسية )(accuracyالمؤشرات التحديد ومعامل ،precision) ودرجة ،f1 (f1-score). أربع عبر النتائج تُظهر ذلك، إلى إضافة أن خوارزمية البيانات دمج k-meansمجموعات أن المحققة النتائج تُثبت معينة. بيانات التصنيف ضمن مجموعات دقة تحسين في إيجابي بشكل تُسهم .التطبيق والكفاءة لهذا الحل في االستخدامات الواقعيةاختيار الميزات مع تقنيات التعلم المجمع يعد حالً فعاالً للكشف عن التصيد االحتيالي، ويظهر قابلية mailto:aliraheem2201m@sc.ubaghdad.edu.iq <4d6963726f736f667420576f7264202d20d2e5d1c7c120e3d8d120e6cf20c7d3d1c7c120e6d3caed20e6e4e6d132362d203336> this is an open access article under the cc by license : al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 18, no. 3, september, (2022) p. p. 2636 assessment of ornamental plants tolerance for acute exposure of acetaminophen and methylparaben in constructed wetlandsa preliminary study zahraa hasan mutar* ahmed a. mohammed** israa abdulwahab al-baldawi*** siti rozaimah sheikh abdullah**** nur ’izzati ismail***** **department of architecture engineering/ college of engineering/ university of wasit/ iraq **department of environmental engineering/ college of engineering/university of baghdad/ iraq ***department of biochemical engineering/ al-khwarizmi college of engineering/ university of baghdad / iraq ****,*****department of chemical and process, faculty of engineering and built environment/ universiti kebangsaan malaysia/ malaysia *email: zhassan@uowasit.edu.iq **email: ahmed.abedm@yahoo.com ***email: israa@kecbu.uobaghdad.edu.iq ****email: rozaimah@ukm.edu.my *****email: nurezatyismail@ukm.edu.my )received 28 march 2022; accepted 14 august 2022 ( https://doi.org/10.22153/kej.2022.08.002 abstract the study aims to select suitable ornamental plant species that can survive relatively with high concentrations of acetaminophen and methylparaben in constructed wetlands. alternanthera spp, asparagus aethiopicus and chlorophytum comosum are examined to withstand three initial concentrations, 20, 100 and 200 mg/l of acetaminophen and methylparaben. a total of 21 plastic pails with each 3 l capacity consisting of nine pails are used for each pharmaceutical and personal care products (ppcps) compounds (acetaminophen and methylparaben) for three ornamental plants (alternanthera spp, asparagus aethiopicus and chlorophytum comosum), with three pails as plant controls. the results reveales that both alternanthera spp and chlorophytum comosum exhibite a good tolerance for acetaminophen with a reduction in the total chlorophyll content of about 4.4–12.3% and 3.9–31.9% for alternanthera spp and chlorophytum comosum, respectively. moreover, it is evident that high concentrations (100 and 200 mg/l) of methylparaben adversely affects the chlorophyll content of the three involved plant species. these results indicate that ornamental plants play an important role in the phytoremediation of ppcps and can be considered as an esthetic treatment for hospital wastewater. keywords: ornamental plant, phytoremediation, chlorophyll, pharmaceuticals, and personal care products. 1. introduction the excessive and unconscious consumption of pharmaceuticals and personal care products (ppcps) have introduced enormous quantities of contaminants into the ecological system, as more than 50% of commercial chemicals can cause harmful effects to the environment due to unregulated disposal [1]. ppcps can cause serious effects on the aquatic environment, being predominantly toxic and endocrine disruptors. nonetheless, long-term exposure to sublethal concentrations of ppcps may cause genetic mutations of environmental microorganisms, zahraa hasan mutar al-khwarizmi engineering journal, vol. 18, no. 3, p.p. 2636 (2022) 27 especially pathogenic microorganisms [2]. ppcps are often continuously released into aquatic environments and thus have been frequently detected in water sources in the range of ng/l to mg/l [3]. some ppcps are partially removed in conventional wastewater treatment processes such as coagulation, sedimentation, filtration, and biological treatment; thus, alternative treatment technologies are required [4] for complete removal. phytoremediation employs plants to eliminate contaminants from the environment [5]. in phytoremediation, plants assisted by microorganisms play a vital role in degrading, converting, metabolizing or detoxifying various pollutants from soil, water and air. furthermore, this technology has many benefits and aesthetical values compared with conventional treatment technologies [6]. this technology has attracted great attention due to its numerous advantages, including sustainability, low costs, ease of operation, and application in large areas [7]. constructed wetlands (cws) are engineered systems that mimic the physical, chemical, and microbiological processes prevailing in natural wetlands to eliminate various contaminants [8]. cws are employed to reduce pollutants (nutrients, organic and inorganic waste) in wastewater before discharge into water bodies; further, it represents an alternative to costly conventional sewage treatment techniques [9]. plant characteristics, including the root system and enzymes, have a significant role in cws [6]. to select a suitable plant species for phytoremediation of ppcps, several considerations must be considered, including the climatic conditions and the characteristics of the wastewater. furthermore, the adaptability of the plant to the saturation conditions, the growth potential of roots, and the tolerance to high pollutant concentrations should also be considered [10]. the use of native plants is often preferred due to their high potential for adaptation on the surrounding environmental condition [11]. kurniawan et al. [9] pointed out several plants' high potential, including chloris virgata, rotala rotundifolia, ludwigia adscendens, and trapa natans phragmites australis, pistia stratiotes, azolla pinnata, and lemna minor, in reducing nutrient from organic-rich wastewater in cws. according to abdullah et al. [6], terrestrial plants are the most employed in phytoremediation (62%), followed by aquatic plants (33%), whereas ornamental plant is the least used (5%). macci et al. [12] chose a set of ornamental plants (canna indica, carex hirta, miscanthus sinensis, and zantedeschia aethiopica) to be tested in cws. the researchers justified the reasons for this choice due to the aesthetic value of these plants and being noninvasive. guittonny-philippe et al. [13] believed that resistant and reproductive macrophyte species, including typha spp. or phragmites australis in cws might cause displacement of native plants or disrupt the natural cycles of plant replacement [13]. therefore, the researchers insisted on providing consensual solutions that would achieve the objectives of treatment in cws while ensuring natural biological diversity. chlorophyll is the pigments that mainly exist in chloroplasts and drive photosynthesis by converting the absorbed light into chemical energy. chlorophyll levels may decrease because of plant exposure to various forms of stress such as pollutants, drought, and other environmental factors [14]. this study is conducted to assess the stress of acetaminophen (ac) and methylparaben (mp) on three different types of ornamental plants and compare their responses. photosynthetic pigments (chlorophyll a, chlorophyll b, and total chlorophyll content) are monitored to detect the physical changes that appear on the plants. 2. materials and methods 2.1chemicals and plant material this study was conducted outdoor at the university of baghdad (25-35 °c). two ppcps were involved in this experiment, namely acetaminophen (middle east laboratories co. ltd, iraq) and methylparaben (vwr chemicals, uk). the properties of the relevant ppcps are summarized in table 1 [15]. stock solutions of each acetaminophen and methylparaben at 500 mg/l were prepared in methanol and stored before use. three types of ornamental plants (alternanthera spp, asparagus aethiopicus and chlorophytum comosum) were purchased from alzawraa park, baghdad, iraq. plants were selected due to their availability and suitability to the warm climate of iraq. plants were first acclimated to tap water for one week, and then homogenous plants were chosen for the experiments. zahraa hasan mutar al-khwarizmi engineering journal, vol. 18, no. 3, p.p. 2636 (2022) 28 table 1, properties of ac and mp characteristics acetaminophen (ac) methyl paraben (mp) molecular formula c8h9no2 c8h8o3 molecular weight (g/mole) 151.16 g/mol 152.15 g/mol water solubility (mg/l) 14000 mg/l 25000 mg/l octanol-water partitioning coefficient (log kow) 0.46 1.96 2.2. experimental setup a total of 21 plastic pails with 3 l capacity each were used, which were divided into three groups as shown in figure 1. the two groups (18 pails) were exposed to 20, 100 and 200 mg/l concentrations of acetaminophen and methylparaben in the three selected plants. in contrast, the third group (3 pails) was filled with tap water only as plant controls. synthetic wastewater was prepared at three concentrations (20, 100 and 200 mg/l) of acetaminophen and methylparaben, individually, then was fed at a volume of 1 l in batch mode into pails. the pails were planted with the relevant plant species (one plant which is homogeneous in weight with the other plants) in 2 kg of fine gravel (2–5 mm ɸ). high ppcps concentrations were used in this study to simulate a hypothetical case of acute exposure. the concentration ranges were established based on the previous literatures [13, 14, 16, 17] that pointed out the low ranges of ppcps concentrations observed in industrial effluents and water sources. fig. 1. experimental setup for acute tolerance test. 2.3 chlorophyll content determination the experiment was extended for two weeks. the chlorophyll content of all plants was determined at the end of the experiment (day 14) and compared with the initial values (day 0). visual observation was also adopted to monitor the changes that occur in the growth of plants during the experiment period to determine their tolerance for the high concentrations of pollutants and survival. chlorophyll content was conducted in two replicates for each plant. it was determined spectrophotometrically according to liu et al. [18] at intervals of 0 and 14 days after the first application of acetaminophen and methylparaben. briefly, 0.2 g of fresh plant samples (particularly, from leaves) were homogenized in 20 ml of 80% acetone with about 0.2 g of quartz sand and calcium carbonate until the samples turned white. zahraa hasan mutar al-khwarizmi engineering journal, vol. 18, no. 3, p.p. 2636 (2022) 29 the homogenate left for 3–5 min was then centrifuged and filtered into a brown volumetric flask of 25 ml-metered volume [18]. the absorbance of the supernatants was measured at 663 and 645 nm via spectroscan (80d, usa). chlorophyll a (chl a), chlorophyll b (chl b), and total chlorophyll content were calculated according to the following equations [18]: ( ) ( ) ( )663 645 12.21 2.81× − × =mg g a a chlorophylla fw … (1) ( ) ( ) ( )645 663 20.13 5.03× − × =mg g a a chlorophyllb fw … (2) ( ) = +mg gtotalchlorophyll chlorophylla chlorophyllb … (3) with a663 and a645 are absorbance at 663 nm and 645 nm for chlorophyll a and b, respectively, and fw is the fresh weight (g) of the plant sample. 2.4 statistical analysis all statistical analysis were performed using spss version 21 (ibm, usa). the univariate analysis of variance (anova) was performed at a confidence level of 95% (p<0.05) to specify the influence of the independent variables on the total chlorophyll content in plants. 3. results and discussions 3.1 plant visual observation the tolerance of three types of ornamental plants to relatively high concentrations of acetaminophen and methylparaben was tested for 14 days in order to determine the most suitable plant to be subsequently employed in cws. through visual observation, alternanthera spp showed a superior tolerance to stress induced by both water and acetaminophen; as no signs of wilting were observed on plants in control systems and those that were exposed to acetaminophen involved concentrations (table 2 and 3) during the experiment. on the other hand, the wilting and yellowing were observed on alternanthera spp that were exposed to mp (table 4), particularly at high concentrations (100 and 200 mg/l). on the contrary, the effects of wilting and yellowing appeared on asparagus aethiopicus that were exposed to different concentrations of ac and mp from the fifth day of the experiment and reached to severe dehydration and plants death at the end of the experiment (table 2, 3). the dehydration to which asparagus aethiopicus was exposed was not related to the type or concentration of the pollutant but mainly associated with water stress; since severe dehydration and plant death were appeared on asparagus aethiopicus in control systems, as shown in table 2. as for chlorophytum comosum, plants in control systems grew well, whereas yellowing was observed on the plants due to exposure to high concentrations (100 and 200 mg/l) of both pollutants. table 2, the physical appearance of selected plants in control systems time alternanthera spp asparagus aethiopicus chlorophytum comosum day 0 day 14 tap water tap water tap water tap water tap water tap water zahraa hasan mutar al-khwarizmi engineering journal, vol. 18, no. 3, p.p. 2636 (2022) 30 table 3, the physical appearance of selected plants in acetaminophen-exposed systems ac concentration (mg/l) time alternanthera spp asparagus aethiopicus chlorophytum comosum 20 day 0 day 14 100 day 0 day 14 200 day 0 day 14 ac 20 mg/l ac 20 mg/l ac 20 mg/l ac 20 mg/l ac 20 mg/l ac 20 mg/l ac 100 mg/l ac 100 mg/l ac 100 mg/l ac 100 mg/l ac 100 mg/l ac 100 mg/l ac 200 mg/l ac 200 mg/l ac 200 mg/l ac 200 mg/l ac 200 mg/l ac 200 mg/l zahraa hasan mutar al-khwarizmi engineering journal, vol. 18, no. 3, p.p. 2636 (2022) 31 table 4, the physical appearance of selected plants in methylparaben-exposed systems methylparabalen concentration (mg/l) time alternanthera spp asparagus aethiopicus chlorophytum comosum 20 day 0 day 14 100 day 0 day 14 200 day 0 day 14 3.2 chlorophyll status in plants the reduction in photosynthetic ability can be adopted as an explicit indicator of phytotoxicity that is resulted from exposure to pollutants, as it often arises earlier than the decline in growth parameters [19]. the photosynthetic pigments, is represented by chlorophyll a, chlorophyll b, and mp 200 mg/l mp 200 mg/l mp 200 mg/l mp 200 mg/l mp 200 mg/l mp 200 mg/l mp 20 mg/l mp 20 mg/l mp 20 mg/l mp 20 mg/l mp 20 mg/l mp 20 mg/l mp 100 mg/l mp 100 mg/l mp 100 mg/l mp 100 mg/l mp 100 mg/l mp 100 mg/l zahraa hasan mutar al-khwarizmi engineering journal, vol. 18, no. 3, p.p. 2636 (2022) 32 total chlorophyll, are measured to closely assess the healthy growth trend in the relevant plants during the experiment period. initially, the differences in total chlorophyll content among the three plants involved in the study are not significant; thereafter (day 14), significant differences were observed between asparagus aethiopicus and the other two plants (alternanthera spp. and ahlorophytum comosum) in all exposure lines (ac, mp and tap water). in contrast, the differences between alternanthera spp. and chlorophytum comosum are found to be not significant in all exposure lines. in accordance with the visual observation, the highest reduction in chlorophyll content in control systems (figure 2) is 81.4% in asparagus aethiopicus, followed by 15.9% in chlorophytum comosum and only 6.5% in alternanthera spp. fig. 2. chlorophyll content (a+b) in control systems. error bars refer to standard deviation (n = 2). in the systems that are exposed to ac (figure 3), the reduction of the total chlorophyll content in asparagus aethiopicus is significant for all concentrations (84.9%, 64.6% and 86% for acetaminophen concentrations of 20, 100, and 200 mg/l, respectively). on the other hand, the reduction that is ranged from moderate (3.9– 31.9%) to marginal (4.4–12.3%) in chlorophytum comosum and alternanthera spp, respectively. fig. 3. total chlorophyll content (a+b) in acetaminophen-exposed systems. error bars refer to standard deviation (n=2). a a a a b a 0 1 2 3 c h lo ro p h y tu m c o m o su m a sp a ra g u s ae th io p ic u s a lt e rn a n th er a sp p water control c h lo r o p h y ll a + b ( m g /g f w ) day 0 day 14 a a a a a a a a a a b a a b a b b a 0 1 2 3 c h lo ro p h y tu m c o m o su m a sp a ra g u s a et h io p ic u s a lt e rn a n th e ra s p p c h lo ro p h y tu m c o m o su m a sp a ra g u s a et h io p ic u s a lt e rn a n th e ra s p p c h lo ro p h y tu m c o m o su m a sp a ra g u s a et h io p ic u s a lt e rn a n th e ra s p p 20 mg/l 100 mg/l 200 mg/l t o ta l c h lo r o p h y ll a + b ( m g /g f w ) day 0 day 14 zahraa hasan mutar al-khwarizmi engineering journal, vol. 18, no. 3, p.p. 2636 (2022) 33 the reduction in chlorophyll content at mpsystems is sharp (figure 4) for all plants compared to the reduction achieved in acetaminophen. similarly, asparagus aethiopicus is the most affected as the reduction in the total chlorophyll content that is ranged between 77.2% to 92.7%. furthermore, mp causes a 32.6–39.1% chlorophyll reduction in chlorophytum comosum and 32.6-40.9% in alternanthera spp. ismail et al. [20] confirmed that salicylic acid, at a certain concentration (0.10 mm), could improve the chlorophyll content (73.5 µg/g dw) in ficus deltoidea jack var. trengganuensis; however, the higher concentration (1.00 mm) caused a clear reduction in chlorophyll content (42.1 µg/g dw). baccio et al. [19] investigated the morphophysiological and biochemical effects of the environmental and high levels of ibuprofen (0.02, 0.20 and 1 mg/l) in lemna gibba l. which was considered the smallest ecological indicator for contamination in aquatic environments. the authors confirmed that the detected changes in growth and photosynthetic rates were not sufficient for inducing phytotoxic effects. kudrna et al. [21] reported that a high concentration of acetaminophen (5 mm) could reduce the intensity of photosynthesis in lactuca sativa by a maximum of more than 31% compared to the control. wijaya et al. [22] emphasized that ibuprofen exposure (0, 400, 800, 1,200, 1,600, 2000 mg/l) caused a clear reduction in total chlorophyll content in cowpea (vigna unguiculata). however, the authors pointed out the ability of the cowpea to develop morphological adaptations to cope under ibuprofen stress. fig. 4. chlorophyll content (a+b) in methylparaben-exposed systems. error bars refer to standard deviation (n=2). 4. conclusion ornamental plants that are involved in the study perform differently towards the stresses that are caused by exposure to acetaminophen and methylparaben. alternanthera spp and chlorophytum comosum can tolerate high concentrations of ac without obvious symptoms of suffering, as the total reduction in chlorophyll content does not exceed 12.3% and 31.9% for alternanthera spp and chlorophytum comosum, respectively, highlighting the potential of these species for ac elimination in aquatic systems; however, these plants are less tolerant with similar methylparaben concentrations. water stress causes yellowing and death of asparagus aethiopicus during the experiment, and therefore this plant is unqualified for use in constructed wetlands under hydroponic conditions. it becomes clear that proper selection of plant species in cws may comprehensively improve the pollutant removal rates due to the different responses of the relevant plant species to ppcps. acknowledgements the authors would like to thank the college of engineering and the al-khwarizmi college of engineering, the university of baghdad, and the a a b b a a b a b b b b b b b b b b 0 1 2 3 c h lo ro p h y tu m c o m o su m a sp a ra g u s a et h io p ic u s a lt e rn a n th e ra s p p c h lo ro p h y tu m c o m o su m a sp a ra g u s a et h io p ic u s a lt e rn a n th e ra s p p c h lo ro p h y tu m c o m o su m a sp a ra g u s a et h io p ic u s a lt e rn a n th e ra s p p 20 mg/l 100 mg/l 200 mg/l t o ta l c h lo r o p h y ll a + b ( m g /g f w ) day 0 day 14 zahraa hasan mutar al-khwarizmi engineering journal, vol. 18, no. 3, p.p. 2636 (2022) 34 iraqi ministry of higher education for supporting this research project, and we also express our gratitude to universiti kebangsaan malaysia for the research collaboration through the dip-2019017 grant. 5. references [1] n. yadav, s. p. govindwar, n. rane, h.-j. ahn, j.-q. xiong, m. jang, s. h. kim, b.-h jeon, “insights on the role of periphytic biofilm in synergism with iris pseudacorus for removing mixture of pharmaceutical contaminants from wastewater,” j. hazard. mater., vol. 418, pp. 126349, 2021. 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[20] a. ismail, n. shahidan, n. mat, r. othman, “effect of salicylic acid on carotenoids and chlorophyll content in mas cotek (ficus deltoidea jack var. trengganuensis) leaves and its retinol activity equivalents (rae),” j. pharm. nutr. sci., vol. 10, pp. 25–33, 2020. [21] j. kudrna, f. hnilicka, j. kubes, p. vachova, h. hnilickova, m. kuklova, “effect of acetaminophen (apap) on physiological indicators in lactuca sativa,” life (basel) 23303, 2020. [22] l. wijaya, m. alyemeni, p. ahmad, a. alfarhan, d. barcelo, m.a. el-sheikh, y. pico, “ecotoxicological effects of ibuprofen on plant growth of vigna unguiculata l,” plants, vol. 9, pp. 1473, 2020. ) 2022( 26-36، صفحة 3العدد، 18مجلة الخوارزمي الهندسية المجلد زهراء حسن مطر 36 تقييم تحمل نباتات الزينة للتعرض الحاد لألسيتامينوفين والميثيل بارابين في األراضي الرطبة دراسة أولية -المشيدة احمد عبد محمد*** زهراء حسن مطر* أسراء عبد الوهاب البلداوي** نور عزاتي اسماعيل***** سيتي رزيمه الشيخ عبد هللا**** قسم هندسة العمارة / كلية الهندسة / جامعة واسط / العراق * ق العرا / د بغدا جامعة / الهندسة كلية / يةالبيئ الهندسة قسم**** ق العرا / د بغدا جامعة /الخوارزمي الهندسة كلية / االحيائية الكيميائية الهندسة قسم ** ماليزيا /ماليزيا كيبانغسان جامعة /والبيئة المدنية الهندسة كلية /والعمليات الكيميائية الهندسة قسم ***** ،**** zhassan@uowasit.edu.iq*البريد االلكتروني: ahmed.abedm@yahoo.com***البريد االلكتروني: israa@kecbu.uobaghdad.edu.iq** البريد االلكتروني: rozaimah@ukm.edu.my****البريد االلكتروني: nurezatyismail@ukm.edu*****البريد االلكتروني: الخالصة الميثيل بارابين في األراضي الرطبة واالسيتامينوفين مادتيهدفت الدراسة إلى اختيار أنواع نباتات الزينة المناسبة التي يمكن أن تقاوم تراكيزعالية من تراكيز أولية ( لتحمل ثالثة الخشن والغيالن الزاحف النمول، الهليون مادتي االسيتامينوفين من مجم / لتر) ٢٠٠و ١٠٠و ٢٠المشيدة. تم فحص نباتات استخدام و تم بارابين. سعة ٢١الميثيل ذو بالستيكي بشكل ٣دلو برابين والميثيل االسيتامينوفين من تراكيز لثالث المذكورة الزينة نباتات لتعريض لتر النتائج أن كال من نباتي النمول )، بينما تعرضت النبات الى الماء في الدالء الثالث المتبقية التي مثلت نب مادةدالء لكل ٩منفصل ( اتات السيطرة. أوضحت بحوالي الكلي محتوى الكلوروفيل انخفاض في جيدًا لألسيتامينوفين مع أظهرا تحمالً قد الزاحف النمول ٣١٫٩٣٫٩٪ و ١٢٫٣٤٫٤والغيالن نبات ٪ في مجم / لتر) من ميثيل بارابين أثرت سلبًا على محتوى ٢٠٠و ١٠٠لعالية (، كان من الواضح أن التراكيز ااحف، على التوالي. عالوة على ذلكوالغيالن الز للمل النباتية مهًما في المعالجة دوًرا تلعب الزينة نباتات أن إلى النتائج هذه النباتية الثالثة المعنية. تشير لألنواع العناية الكلوروفيل ومنتجات الدوائية وثات ًيا لمياه الصرف الصحي في المستشفيات. الشخصية ويمكن اعتبارها عالًجا جمال this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 20, no. 4, december (2024), pp. 46-57 corrosion and microhardness behavior improvement of 316l stainless steel via fiber laser surface treatment mustafa majid 1*, enas a. khalid 2 and hayder zghair3 1,2 department of automated manufacturing engineering, al-khwarizmi collage of engineering, university of baghdad, iraq 3 department of engineering, college of science and engineering, southern arkansas university (usa) *corresponding author’s e-mail: mostafa.ali2240m@kecbu.uobaghdad.edu.iq (received 19 june 2023; revised 4 november 2023; accepted 25 december 2023; published 1 december 2024) https://doi.org/10.22153/kej.2024.12.002 abstract this study investigated how fibre laser surface treatment affects stainless steel 316l’s microhardness and corrosion resistance. the laser parameters utilized in this investigation were four different readings of laser power applied at a constant frequency and scanning speed to stainless steel 316l specimens. a digital micro-vickers hardness tester was used to measure the microhardness of the samples before and after laser treatment. the tafel cyclic potentiodynamic polarization technique was employed to study corrosion behaviour. the microstructure of the base metal and the effect of laser power were investigated using optical microscopy. the phases before and after laser treatment were identified through x-ray diffraction, and the cross section of the heat-affected zones and the molten pool’s depth were examined using a scanning electron microscope. results revealed that laser treatment affected microstructural transitional phase alterations. compared with the average microhardness of the base metal, the microhardness of the laser-treated specimens improved to 78.23% as the laser power increased. the increase in microhardness considerably enhanced corrosion resistance to 36.13% relative to that of the base metal. keywords: corrosion; fiber laser; microhardness; ss316l; surface treatment 1. introduction lasers can be utilized as highly adaptable, mouldable thermal sources. lasers can alter the surface properties of specific materials. the high power density and short contact times of lasers produce high heating rates in a thin surface layer. after surface treatment, self-quenching causes fast cooling, which in turn introduces microstructural alterations, such as grain refinement or phase transitions to metastable phases. additional microstructural changes, such as the dissolution or modification of precipitates or residual stresses, alter the surface and subsurface properties of the material. laser surface treatments are considered a well-established method to improve corrosion resistance and surface hardness [1]. lasers have many exceptional properties, such as non-contact processing, improved product quality, low cost, high production, decreased finishing operations and processing, high material use and a small heat-affected zone. the need for laser material processing is increasing because of these properties [2]. the usage of lasers for material processing may be classified into two groups: (a) uses that require minimal energy or power and do not appreciably affect phases and (b) uses that require a considerable amount of energy to accomplish. the first group includes processes for annealing and etching semiconductors, curing polymers and labelling integrated circuit substrates. the second group comprises cutting, welding, melting and heat treatment [3]. engineering material failure can be categorized into numerous categories: corrosion, oxidation, fatigue and wear/abrasion. material mailto:mostafa.ali2240m@kecbu.uobaghdad.edu.iq https://doi.org/10.22153/kej.2024.12.002 mustafa majid al-khwarizmi engineering journal, vol. 20, no.4, p.p. 4657 (2024) 47 failure may start at the surface because of two main factors: vulnerability of free surfaces to environmental deterioration and high intense external load at the surface. to eliminate failure that starts at the surface, engineers can alter the surface microstructure and composition of the near-surface region of a component without changing the bulk [4,5]. the most popular conventional surface engineering methods are galvanizing, diffusion coating, carburizing, nitriding and flame/induction hardening. however, these methods have several drawbacks, such as low precision, limited flexibility range and high time, energy and material consumption. ti alloys, co alloys and stainless steels are frequently used for biomedical implant purposes. metals and their alloys are essential to structural biomaterials used in reconstructive surgery, especially orthopedics. given that the surfaces of these metals and their alloys are prone to corrosion, laser technology is employed to alter their mechanical characteristics (e.g. hardness). the majority of laser surface modifications has been applied to ferritic (430), martensitic (420) and austenitic (304) stainless steels to reinforce their resistance to pitting corrosion. the most common implant material is 316l austenitic stainless steel because it is inexpensive [6]. austenitic stainless steel is one of the most frequently utilized alloys in maritime, biomedical and aerospace industries because of its superior flexibility and corrosion resistance [7]. stainless steel 316l (ss316l) is excellent for corrosion resistance applications because it can form a coherent, adhesive, oxide-thin layer of chromium (cr2o3, a corrosion barrier). however, this layer of oxide chromium created on the surface of the implant metal is unstable because the layer tends to localize corrosion in long-term implant applications. moreover, the human body is a complex and challenging electrolytic environment for biomaterial applications [8,9]. the corrosion protection provided by laser treatment is attributed mainly to the grain refinement of the top surface layer [10]. grain refinement can improve strength, such that a reduction does not create microporosity [11]. numerous investigations have been performed to enhance the surface qualities, such as corrosion resistance, wear and hardness, of metals and alloys because of these materials’ importance in daily life. for aisi ss316l, the processes of low-energy, high-current pulsed electron beam (lehcpeb) corrosion and wear improvements were studied by zou et al., who found that aisi ss 316l confirms the high potential of the lehcpeb technique for improving the aforementioned properties, particularly when the number of pulses is sufficiently high [12]. muna investigated the effects of nd:yag laser treatment on the surface modification and corrosion behaviour of the most popular implant biomaterial (ss316l) in an artificial saliva solution at a temperature of 37 °c. the results showed that a decrease in the pulse repetition rate or frequency from 1 hz to 6 hz at 1,064 nm results in surface modification, grain refinement and a slight improvement in hardness. corrosion tests revealed that the samples treated with 1 hz at 532 and 1,064 nm had higher corrosion resistance than the untreated base alloy and other treated samples [13]. abbas et al. examined how pulsed laser surface melting affects aisi 304 stainless steel’s corrosion and wear properties. the results demonstrated that lsm enhances the hardness and wear resistance of treated samples. the corrosion test also revealed that treated samples have stronger resistance to pitting corrosion than untreated ones [14]. singh et al. studied the effects of laser surface processing on the surface microstructure and corrosion behaviour of ss316l and ti-6al-4v. they found that metal ions are generated during the corrosion process (laser power of 500–1,500 w) in an ambient environment. in the re-solidified area of ss316l, columnar dendrites and tiny grains create a homogeneous surface microstructure. the researchers also discovered that grain size gradually increases from the substrate towards the treated surface. compared with the corrosion characteristics of untreated counterparts, the corrosion characteristics of ti-6al-4v improve, whereas those of ss316l to worsen after laser processing. ss316l’s corrosion resistance is affected by variations in laser power, but that of ti6al-4v is not substantially affected [15]. tangkwampian et al. studied the influence of fibre laser surface modification on the corrosion behaviour of ss316l and found that laser treatment increases the pitting potential by 40%. the results also showed a shift in corrosion potential to a more favourable one. the corrosion improvement results led to the conclusion that the corrosion protective layer on the newly laser-treated surface can reduce the material’s pitting tendency [16]. ganesh dongre revealed the effects of different laser parameters on the microhardness of ss316l after laser hardening. they obtained a 25% increase in hardness after laser hardening and a hardened depth of up to 400 microns [17]. bakhtiari et al. used a high-power nd:yag pulsed laser at a maximum power of 3.5 kw to study the hardness of aisi4130 steel. some of the results showed that the coefficient of friction decreases from 0.77 in the base metal to 0.39 in the hardened samples [18]. mustafa majid al-khwarizmi engineering journal, vol. 20, no.4, p.p. 4657 (2024) 48 previous researchers have investigated and used several laser methods, including laser surface hardening and melting, with a continuous wave and pulsed mode under different laser parameters, such as power density, beam power, travel speed and pulse duration. this study investigates fibre laser surface treatment and the effects of laser power on the microhardness, corrosion resistance and microstructure of ss316l by using a high frequency (khz), high scanning speed, and very small spot size (µm). 2. materials and methods 2.1 materials the material used in this study was wrought ss316l. austenitic ss316l was utilized in this study because of its vast application in the biomedical field, and it is used in orthopedics and dental implants. this steel is a rolled sheet with 30 mm thickness. table (1) shows ss316l’s chemical composition, and table (2) presents its mechanical properties. table 1. ss316l’s chemical composition. actual test element c si mn p s n cr mo ni fe value % 0.027 0.3 1.38 0.03 0.004 0.09 17.1 2.03 11.5 bal. standard value % ≤ 0.03 0.75 2 0.045 0.03 0.1 16.5–18.5 2–2.5 10–14 bal. table 2. mechanical properties of ss316l [19]. 2.2 methods the first step in sample preparation was cutting the samples into cylindrical shapes with dimensions of (4×9, 5×10, 20×10 and 8×20 mm) in height and diameter, as shown in figure (1). the samples were ground using silicon carbide (sic) paper with different grids (220, 400 and 800) for corrosion, microhardness, scanning electron microscopy (sem) and x-ray diffraction (xrd) tests. the samples were ground using sic paper with grids of 220, 400, 600, 800, 1,200 and 2,000 for the microstructure test, and the samples were micropolished with a diamond suspension of 0.1 µm particle size to achieve a good finish for vivid findings. next, alcohol was employed to wash the samples and remove oils from the surface to obtain precise details of the microstructures under a microscope. the cross-section surfaces were etched for 60 s by using marable’s reagent etchant solution [20]. marable’s etchant contains 50 ml of hcl, 50 ml of cuso4 and 10 ml of distiller water. the etched samples were dried in an oven after being rinsed with distilled water and alcohol. the microstructure of the base metal and the effect of laser spot size with various laser power were investigated through optical microscopy. the crosssectional area of the heat-affected zones and the molten pool’s depth were examined sem. the phases before and after laser treatment were identified via xrd. a digital micro-vickers hardness tester was used to measure the microhardness of the samples in hv before and after laser treatment, and a microhardness test was conducted at a load 1 kg for 15 s. the tafel cyclic potentiodynamic polarization technique and the winking m lab 200 potentiostat from bankelektronik software were employed to examine the corrosion behaviour. the samples were immersed in seawater solution for an electrochemical corrosion test for 15 min. density-kg/𝒎𝟑 8,000 micro hardness-hv 206.3 modulus of elasticity-gpa 193 thermal conductivity at 20 °c w/m k 15 specific heat-0 °c –100° c ( j/kg.k) 500 mustafa majid al-khwarizmi engineering journal, vol. 20, no.4, p.p. 4657 (2024) 49 fig. 1. types of samples used in this study. 2.2.1 laser system specifications a laser beam was used as a heat source to enhance the surface metal’s characteristics through phase changes. the specifications of the laser device used in the surface treatment are listed in table (3), and the laser parameters are given in table (4). the device is shown in figure (2). the ezcad2 software program was used to determine the laser power, laser scanning speed and laser frequency for this study. in this software, the laser path can be determined by hatch. the zigzag path was used in this study because of its popularity and efficiency. this work was performed in al-nahrain university laser and optoelectronics engineering department. table 3. specification of the laser machine used in this work. specification description units brand name wuxi raycus fiber laser technologies co., ltd. type fiber optics laser origin china power 0–31 w scanning speed 0–6000 mm/s frequency 30–60 khz applications surface processing, marking, engraving table 4. variable fibre laser power with other parameters being constant. no. parameters values units 1 power 3, 5, 7.5, 10 w 2 scanning speed 3,000 mm/s 3 frequency 30 khz 4 wavelength 1,064 nm 5 spot size 70 µm 6 pulse duration 127 ns 7 working distance 20 cm 8 medium air (a) (b) fig. 2. laser device system: (a) fibre laser device and (b) components of the fibre laser device. mustafa majid al-khwarizmi engineering journal, vol. 20, no.4, p.p. 4657 (2024) 50 2.3 microhardness test this microhardness test determined the material’s hardness or resistance to the penetration of the indenter. the vickers hardness test method employed a digital device (vickers hardness tester th714). the main parts of this device are the microscope, indenter, screw and testing table, as shown in figure (3). the diamond indenter was indented in the test material as a pyramid with a square base and a top angle of 136° between opposite faces subjected to a load of 9.8 n. the full load of 9.8 n was normally applied for 15 s. three readings were obtained, and the averaged values represent the microhardness of all the samples (as received and treated). this task was performed in university of baghdad, al-khwarizmi college of engineering, automated manufacturing engineering department, iraq. hardness was measured using vickers’ law as follows [21]: hv = 1.854 𝑝 𝑑2⁄ , … (1) where hv is vickers hardness ( 𝑘𝑔 𝑓 𝑚𝑚2⁄ ), p is the load applied (kg f) and d is the indentation diameter (mm). fig. 3. microhardness test device. 2.4 corrosion test cylindrical samples measuring 20 mm in diameter and 8 mm in height, as shown in figure (1), were immersed in seawater (3.5 wt.% nacl solution) at 25 °c for an electrochemical corrosion test. cycle polarization experiments were conducted using the winking m lab 200 potentiostat from bank-elektronik and a standard electrochemical cell, as indicated in figure (4). fifteen minutes of electrochemical measurements were performed with the potentiostat at a scan rate of 3 mv/sec. the key results were expressed in terms of corrosion potential (e corr.) and corrosion current density (i corr.). the tafel slopes were also measured in this study [22]. this examination was done in the ministry of science and technology’s inspection of materials laboratory. fig. 4. electrochemical corrosion cell test. 3. results and discussions 3.1 effect of laser power on microhardness table (5) shows the measured microhardness of the samples treated at different laser power with a constant speed and frequency on the ss316l metal surface. the highest value of microhardness (367.7 hv) was found in sample (a3), and the lowest value of microhardness (183.8 hv) was in the sample (a4). the base metal’s value was 206.3 hv, as shown in table (5) and figure (3). mustafa majid al-khwarizmi engineering journal, vol. 20, no.4, p.p. 4657 (2024) 51 table 5. effect of laser power on the microhardness of ss316l. the increase in microhardness in most of the treated samples was due to grain refinement of the metal surface [23,24]. this study revealed that increasing the laser power from 3 w to 7.5 w increased the microhardness of the surface metal, but increasing the laser power from 7.5 w to 10 w decreased the microhardness of the metal surface. this decrease was due to the relationship between laser power and the melted surface [25]. figure (3) shows the effect of laser power on the microhardness of the surface metal. fig. 3. effect laser power on microhardness. 3.2 effect of laser power on corrosion resistance table (6) shows the influence of lasers on the electrochemical corrosion test done in nacl solution (3.5 wt.%). the sample chosen for the corrosion test depended on the highest readings of the microhardness test, and a comparison was made with the base metal. the cyclic polarization curve for sample a shows the result of the untreated sample, and that for sample b shows the result of the laser-treated sample. figure (4a) presents the cyclic polarization curve for the base metal (ss316l). on the basis of the corrosion test in nacl solution (3.5 wt.%), pitting corrosion (loop cycle) was observed. this figure contains tafel and cyclic polarization curves. the tafel equation was utilized to determine the corrosion rate (in material per year). the results showed that pitting corrosion increased when the corrosion current (i corr.) increased, as indicated in table (6). meanwhile, corrosion behaviour (pitting corrosion) decreased with the loop cycle compared with that in sample (a), as indicated in figure (4b). % improvement average microhardness (hv) microhardness readings frequency (khz) speed (mm/s) power (w) sample 3 2 1 206.3 199.6 205.2 213.0 base metal ss316l 2.22 % + 4.16 % + 78.23 % 10.9 % 201.7 214.9 367.7 183.8 196.1 205.0 362.1 169.8 197.8 211.0 367.9 184.1 211.3 228.9 373.1 197.6 30 30 30 30 3,000 3,000 3,000 3,000 3 5 7.5 10 a1 a2 a3 a4 mustafa majid al-khwarizmi engineering journal, vol. 20, no.4, p.p. 4657 (2024) 52 table 6. corrosion results for the base metal and laser-treated sample. samples power (w) speed (mm/s) frequency (khz) i corr. (na/c𝒎𝟐) e corr. (mv) corrosion rate (material per year = 0.43) % improvement base metal (a) _ _ _ 283.51 -331.5 121.9 (b) 7.5 3000 30 18.71 -211.7 8.0 + 36.13 % (a) (b) fig. 4. corrosion results of (a) base metal sample a (before laser treatment) and (b) sample b (after laser treatment). the results of the corrosion tests showed that the corrosion resistance of the laser-treated sample was better than that of the untreated sample. this improvement in corrosion resistance confirmed that a layer of chromium oxide was formed as a protective layer on the surface; it slowed down corrosion and improved the resistance to pitting corrosion [14,15,16]. 3.3 effect of laser power on the microstructure of ss316l the laser parameters affected the metal surface and surface morphology, leading to an increase in the intensity of the austenite phase (γ-fe) due to grain refinement [23,24] and showing the presence of the alpha ferrite phase (α-fe), as presented in table (7). table 7. xrd data. xrd phases average microhardness (hv) frequency (khz) speed (mm/s) power (w) sample γ-fe 206.3 base metal ss316l γ-fe + α-fe 367.7 30 3000 7.5 a3 mustafa majid al-khwarizmi engineering journal, vol. 20, no.4, p.p. 4657 (2024) 53 the microstructure of the base metal ss316l before and after laser treatment is shown in figure (5). it explains the grain structure and phases of ss316l, which consists of an austenite phase with a regular distribution of grain boundaries with twin boundaries. xrd explained the phase transformation, as shown in figure (6). the sample chosen for the xrd test depended on the highest readings of the microhardness test, and a comparison was made with the base metal. (a) (c) (b) (d) fig. 5. microstructure of ss316l at 400×. (a) base metal after etching using marable’s etchant. (b) laser-treated sample at laser power of 7.5 w, scanning speed of 3,000 mm/s and frequency of 30 khz after etching. (c and d) laser-treated sample at laser power of 7.5 w, scanning speed of 3,000 mm/s and frequency 30 khz before etching. (a) (b) fig. 6. xrd data of the (a) base metal (before laser treatment) and (b) sample a3 (after laser treatment). mustafa majid al-khwarizmi engineering journal, vol. 20, no.4, p.p. 4657 (2024) 54 3.4 effect of laser power on the molten depth of ss316l laser treatment was applied to the outer layer of the sample’s surface. sem examination helped examine the depth of the molten pool. the sample chosen for the sem test, which was sample a3 with a laser power of 7.5 w, depended on the highest reading of the microhardness test. figure (7c) shows that the melted depth at laser power of 7.5 w was 4.533 μm. three zones, namely, melted, heataffected and base metal zones, can be seen in all the figures. (a) (b) (c) fig. 7. sem photo of sample a3 showing the depth of the molten pool at (a) 600×, (b) 1,300× and (c) 2,500× with laser power of 7.5 w, scanning speed of 3,000 mm/s and frequency of 30 khz. 4. conclusions surface treatments are necessary for materials to achieve desirable mechanical and surface properties. in this study, the surface and mechanical properties of ss316l were enhanced by laser surface treatment. laser surface treatment generally improved the corrosion resistance, microhardness, wear resistance, fatigue strength and tensile strength of the materials. the following conclusions were obtained in this study. 1. surface treatment of ss316l by pulsed fibre laser revealed that the laser affected grain refinement directly. 2. most samples showed an increase in microhardness. among the samples, sample a3 (367.6 hv) with 7.5 w of laser power had the largest increase in microhardness, which was mustafa majid al-khwarizmi engineering journal, vol. 20, no.4, p.p. 4657 (2024) 55 78.23% more than that of the base metal (206.3 hv). 3. corrosion resistance at a laser power of 7.5 w increased when the microhardness of the lasertreated materials increased to i corr. = 283.51 na/𝑐𝑚2 compared with i corr. = 18.71 na/c𝑚2 of the base metal. 4. in comparison with the base-metal sample, the laser-treated sample showed the presence of the alpha ferrite phase (α-fe) with an intensified austenite phase (γ-fe) due to grain refinement. 5. according to the sem data, the depth of the sample treated with laser power of 7.5 w was approximately 4.5 mµ. acknowledgement the authors would like to express their sincere appreciation and gratitude to the university of baghdad, al-khwarizmi college of engineering, automated manufacturing engineering department; university of technology’s production and metallurgy department; and university of al-nahrain’s laser and optoelectronic department for their help in the experimental work. references [1] b. l. mordike surface modification by lasers. in: materials science and technology (edited by r. w. cahn, p. haasen and e. j. kramer), vol. 15, pp. 111-136. vch verlagsgesellschaft, weinheim, germany, 1991. 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[25] li, jianguo; li, huan; liang, yu; liu, pingli; yang, lijun; wang, yaowei, “effects of heat input and cooling rate during welding on intergranular corrosion behavior of high nitrogen austenitic stainless steel welded joints”. corrosion science, april 2020. https://ucpcdn.thyssenkrupp.com/_legacy/ucpthyssenkruppbamxuk/assets.files/material-data-sheets/stainless-steel/stainless-steel-1.4404-316l.pdf https://ucpcdn.thyssenkrupp.com/_legacy/ucpthyssenkruppbamxuk/assets.files/material-data-sheets/stainless-steel/stainless-steel-1.4404-316l.pdf https://ucpcdn.thyssenkrupp.com/_legacy/ucpthyssenkruppbamxuk/assets.files/material-data-sheets/stainless-steel/stainless-steel-1.4404-316l.pdf https://ucpcdn.thyssenkrupp.com/_legacy/ucpthyssenkruppbamxuk/assets.files/material-data-sheets/stainless-steel/stainless-steel-1.4404-316l.pdf https://www.sciencedirect.com/topics/physics-and-astronomy/hardness https://www.sciencedirect.com/topics/physics-and-astronomy/hardness (2024) 46-57، صفحة 4، العدد20مجلة الخوارزمي الهندسية المجلد مصطفى ماجد حسين 57 معالجة الباستخدام 316lللفوالذ المقاوم للصدأ والصالبة الدقيقة تقييم تحسين سلوك التآكل بليزر األلياف يةالسطح 3حيدر صغير ، 2خالد ايناس عبد الكريم ، *1حسين مصطفى ماجد ، بغداد، العراقجامعة بغداد ،كلية الهندسة الخوارزمي ،قسم هندسة التصنيع المؤتمت 1،2 ، الواليات المتحدة االمريكيةجامعة جنوب أركنساس ،والهندسةقسم الهندسة، كلية العلوم 3 mostafa.ali2240m@kecbu.uobaghdad.edu.iq :البريد االلكتروني* المستخلص ومقاومته للتآكل. معلمات l316الصالبة الدقيقة للفوالذ المقاوم للصدأ من النوع فيلياف يزر االلتبحث هذه الورقة في كيفية تأثير المعالجة السطحية ب . l316على عينات الفوالذ المقاوم للصدأ ثابتة مطبقة سرعة و مسح ثابت بتردد و الليزر بأربع قراءات مختلفة طاقةالليزر المستخدمة في هذا الفحص هي تم استخدام تقنية االستقطاب وقبل وبعد العالج بالليزر. hvبوحدة تم استخدام جهاز اختبار صالبة فيكرز الرقمي الصغير لقياس الصالبة الدقيقة للعينات و تم و(. omدراسة البنية المجهرية للمعدن األساسي وتأثير قوة الليزر باستخدام المجهر الضوئي ) و تحتآكل. لدراسة سلوك الت tafelالديناميكي الدوري . تم فحص المقطع العرضي للمناطق المتأثرة بالحرارة وعمق البركة المنصهرة xrdتحديد المراحل قبل وبعد العالج بالليزر باستخدام حيود األشعة السينية ، تحسنت فضال عن ذلكتغيرات المرحلة االنتقالية المجهرية. فيكشفت النتائج أن العالج بالليزر أثر وقد (.semاإللكتروني الماسح )باستخدام المجهر ادة الصالبة الصالبة الدقيقة للمعدن األساسي. أدت زيعلى المعلمات المطبقة مقارنة بمتوسط باالعتماد% مع زيادة طاقة الليزر؛ 78.23الصالبة الدقيقة إلى .% مقارنة بالمعدن األساسي36.13الدقيقة إلى تعزيز مقاومة التآكل بشكل كبير إلى mailto:mostafa.ali2240m@kecbu.uobaghdad.edu.iq https://doi.org/10.22153/kej.2024.12.002 this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 18, no. 4, december, (2022) p. p. 1431 the influence of support materials on the photo-fenton-like degradation of azo dye using continuous nanoparticles fixed-bed column zainab a. mahmoud* mohammed a. atiya** ahmed k. hassan*** *,***department of biochemical engineering/ al-khwarizmi college of engineering/ university of baghdad/ iraq ***environment and water directorate/ ministry of science and technology/ baghdad/ iraq zainab.amahmoud@gmail.comemail: * atiya@kecbu.uobaghdad.edu.iqemail: ** ahmedkhh71@gmail.com: email*** (september 2022 20 2022; acceptedseptember 1 received) https://doi.org/10.22153/kej.2022.09.002 abstract this study used a continuous photo-fenton-like method to remediate textile effluent containing azo dyes especially direct blue 15 dye (db15). a eucalyptus leaf extract was used to create iron/copper nanoparticles supported on bentonite for use as catalysts (e@b-fe/cu-nps). two fixed-bed configurations were studied and compared. the first one involved mixing granular bentonite with e@b-fe/cu-nps (gbe@b-fe/cu-nps), and the other examined the mixing of e@bfe/cu-nps with glass beads (glass beads-e@b-fe/cu-nps) and filled to the fixed-bed column. scanning electron microscopy (sem), zeta potential, and atomic forces spectroscopy (afm) techniques were used to characterize the obtained particles (nps). the effect of two main parameters including contaminant flow rate concentration in continuous fixed-bed systems was investigated. to optimize both studied systems, the response surface methodology using the central composite design (ccd) was used. the analysis shows that the removal efficiency for gb-e@b-fe/cu-nps was 81% and for glass beads-e@b-fe/nps was 62.6%. keywords: glass beads; fixed-bed column; iron/copper nanoparticles; granular bentonite; photo-fenton-like. 1. introduction due to the extensive use of organic dyes in different industries, dyes are one of the most often discovered organic contaminants in natural waters. they are regularly identified in surface water, groundwater, and wastewater effluents [1]. among the various dyes used in industries, azo dyes are the major proportion of these dyes and are difficult to degrade [2]. these organic dyes could react with other chemical compounds and produces hazardous and nonbiodegradable by-products. in addition, the presence of these dyes in water causes serious diseases such as cancer, splenetic sarcomas, and hepatocarcinoma [3]. as a result, there is increased interest in building a stable procedure for removing these azo dyes from water. there has been extensive investigation on the ability of physical methods (adsorption, reverse osmosis, membrane filtration, and ion exchange) and biological degradation (aerobic and anaerobic microbial degradation and enzymic degradation) to remove these nondestructive organic dyes [4]. however, these methods have drawbacks such as, the difficult and slow procedure of biological degradation whereas mailto:zainab.amahmoud@gmail.com mailto:atiya@kecbu.uobaghdad.edu.iq mailto:ahmedkhh71@gmail.com https://doi.org/10.22153/kej.2022.09.002 zainab a. mahmoud al-khwarizmi engineering journal, vol. 18, no. 4, p.p. 1431 (2022) 15 physical methods are typically non-destructive or ineffective [5]. hydrogen peroxide is decomposed by ferrous ions (fe+2) in the fenton process, releasing hydroxyl free radicals •oh, which are regarded as a powerful oxidizing agent [6]. this method is advantageous because it requires minimal resources and has a short treatment time [7]. but it also has some drawbacks, like a narrow ph, high secondary waste mainly fe+3, and difficulty restore the catalyst (fe+2) [8]. to solve the challenges, the heterogeneous fenton is suggested as an effective environmentally friendly, and inexpensive process [10]. in general, zero-valent iron (zvi-nps) achieved great success in heterogeneous fenton-like processes due to the ease and cheapness of preparing [11], and the production of fe+2 enhanced by using zvi-nps [5]. additionally, the activity of zvi-nps highly increase by depositing transition noble metals like copper, nickel, palladium, and silver on the surface of zvi-nps [12]. to enhance catalyst dispersity and avoid the aggregation it necessary to support the nanoparticles of materials exhibit good thermal and mechanical stability. heterogeneous fenton catalysts to have a high catalytic activity [17]. bentonite possesses exceptional physicochemical properties, offers a high specific surface area, and is inexpensive [13] . water treatment may greatly benefit from coupling advanced oxidation and green catalysts. green nanotechnology has received considerable attention in recent years [14]. several chemical and physical methods are obtainable for production of metallic nanoparticles, but these methods have many problems and drawbacks such as use of hazardous chemicals as reducing agents, limited material exchanges, large energy requirements, ecological toxicity, and economic inefficiency [15]. as a result, there is an urgent need to find a method to create nanoparticles with high efficiency, low cost, and environmentally safe. presently, an easy, sustainable, quick, and ecofriendly green synthesis method employing plant leaves extract use as alternative for other traditional methods [16]. the plant extract contains many biomaterials like polyphenol, vitamin, flavonoids, polysaccharide, sugar, and alkaloids which represent secondary metabolites with redox ability [17]. in addition, these biomolecules are considered as a capping, and chelating agent covering the nanoparticles and prevents it nanoparticles from agglomeration [18]. continues reactors are preferred for large scale wastewater operating units, it has also been established primarily in lab-scale studies and the fixed-bed reactor is an example of continuous system. this system is characterized by ease of catalyst separation from the liquid and regenerated, providing excellent industrial development opportunities [19]. the fixed-bed is easy to build and has a ideal flow pattern that allows for increased contact between the catalyst and the reactant and lower maintenance costs [20]. it is also easily scalable from the lab or pilot plant to full production levels. [21]. once the process initiates, the oxidation reaction start and the contaminates are treaties as pass over the catalyst [12] . the presents study involved the use of eucalyptus leaves extract for green synthesis of iron/copper nanoparticles loaded on bentonite (e@b-fe/cu-nps). this catalyst was employed to investigate the degradation of direct blue dye (db15) through continuous photo-fenton-like process using fixed-bed column. the granular bentonite and glass beads as support materials for e@b-fe/cu-nps in fixed-bed column. 2. materials and method 2.1. chemicals and reagents the bentonite of 75μm particles size was brought from state company for mining industry, iraq. leaves of the eucalyptus tree were gathered from baghdad university, iraq. the glass beads were brought from the glass workshop of the university of baghdad. other chemicals and their source are illustrated in table 1. the direct blue 15 (db15) dye was brought from central drug house company (mw: 992.8 g/mol, λ max: 594 nm). zainab a. mahmoud al-khwarizmi engineering journal, vol. 18, no. 4, p.p. 1431 (2022) 16 table 1, chemicals and their sources. chemicals sources cupper sulfate (ⅱ) (cuso4.5h2o) iron sulfate(ⅱ) (feso4.7h2o) purchased from alpha chemika company h2o2 (30% w/v) purchased from the sdfcl company ethanol (≥ 99.8%) purchased from honeywell 2.2. e@b-fe/cu-nps preparation to remove dust and stuck dirt, eucalyptus leaves were gathered and washed. after a duration, the leaves were dried in a hot oven at 50 ℃ for 12 hours. the leaves were ground into a fine powder after they had completely dried and become crushable (size ranged between 1.4-2 mm). following that, 10 g of eucalyptus leaf powder was added to 150 ml of deionized water and boiled for 30 minutes at 80 °c. after cooling. thereafter, the vacuum filtration was used to filtrate the extract and eliminate any suspended leaves. to finish the e@b-fe/cu-nps preparation, 2 g bentonite was mixed into 100 ml deionized water and stirred for 30 minutes at room temperature. meanwhile, salt solutions were made by dissolving 1.5 g of iron (ii) sulfate and 0.4 g of copper (ii) sulfate in 50 ml of deionized water. the salt solutions were then combined into the bentonite solution and stirred for 60 minutes in an ultrasonic vibration water bath. then, with constant stirring, a 100 ml of eucalyptus extract was added gradually to the bentonite and salts mixture. after several drops of the extract were added, the color of the mixture changed from yellow to black, indicating that fe+2 and cu+2 were reduced to zero-valent [22]. following that, the black precipitate of e@bfe/cu-nps was vacuum filtered and washed directly with distilled water, followed by absolute ethanol. the e@b-fe/cu-nps were then dried at room temperature overnight before being ground into a fine powder with a mortar. figure 1 depicts the steps for preparing e@b-fe/cu-nps. fig. 1. e@b-fe/cu-nps preparation steps. 2.3.characterization of e@b-fe/cu-nps the resultant nanoparticles were characterized using scanning electron microscopy (sem) to specify the size and shape. while the chemical compositions were analysed through energy dispersive x-ray spectroscopy (edax). the zeta potential was used to determine stability of e@bfe/cu-nps in collide suspension. the morphology and surface roughness of e@b-fe/cu-nps were specified through atomic force spectroscopy (afm). zainab a. mahmoud al-khwarizmi engineering journal, vol. 18, no. 4, p.p. 1431 (2022) 17 2.4.design of photoreactor to design a photoreactor an aluminium cylindrical container with diameter of 40 cm and length 50 cm was used to install the lamps on it and to provide a reflective surface. twenty-four lamps were used these lamps emit uv light type a with intensity of 1 w/m2 and wavelength of 365 nm. the distance between the lamps and the reaction cell was fixed at 10 cm. to prevent the outside light from entering the reactor, the cylindrical container was placed inside opaque wooden box with dimensions of (60*60*60 cm). two cooling fans were used to keep the temperature inside the reactor at required value. moreover, the thermocouples used to observe the temperature during the reaction. the schematic diagram of the photoreactor is shown in figure 2 fig. 2. schematic diagram of continuous photo-fenton-like process using fixed-bed column. 2.5. fixed-bed experiment the fixed-bed experiments were performed using pyrex column (33 cm length, 2.2 cm diameter). the removal of db15 through fixed-bed column were examined using two different fixedbed arrangements illustrated in figure 3 a, b. to provide a uniform velocity profile for passing fluid, glass beads (size 1-1.5 mm) were packed. a 1 g of catalysts was held on granular bentonite (size 1-1.5 mm) and packed in the column, figure 3a. the glass beads also used to fill the upper part of the column and occupy space of (10 cm thickness). the other column arrangements (figure 3b) involved mixing 1 g of e@b-fe/cu-nps with glass beads of size (0.5-1 mm). the stock solution of 1000 mg/l of dye was prepared and used to prepared required dye concentrations. the ph of solution was adjusted to 3.5 and h2o2 dosage of 7.5 mmol/l was added to the db15 solution. to initiate the experiment, the column fixed at the centre of photoreactor while the inlet db15 solution kept in dark box and a peristaltic pump was used to pumping the contaminant solution through the column. before started the experiments, the column is filled with glass beads only to check if there is any effect or removal of dye, the results indicate that the glass beads alone do not affect dye removal, thereafter, the column is filled with glass beads, and 8 cm granular bentonite (without e@b-fe/cu-nps) to check if the bentonite affect the removal of dye, a 57.5 g/l dye concentration (without h2o2) was pumped into the column and the outlet concentrations were checked. the removal efficiency does not exceed (17%) with a qtotal of (0.629 mg) only. this result indicates that both the adsorption and the fenton processes occurred when e@b-fe/cu-nps mixed with granular bentonite. zainab a. mahmoud al-khwarizmi engineering journal, vol. 18, no. 4, p.p. 1431 (2022) 18 fig. 3. (a) fixed-bed column of gb-e@b-fe/cu-nps, (b) fixed-bed column of glass beadse@b-fe/cu-nps 2.6. design of experiments response surface methodology (rsm) is a statistical method being useful for the optimization of processes and widely used for experimental design. rsm is useful tool help to understand the relationship between parameters and their effect on responses [23]. optimization the process by rsm is more efficient for analysing experimental results rather than the conventional one-factor-at-a-time approach. in this study, central composite design (ccd) was employed for the optimization of continuous photo-fenton-like treatment of db15 wastewater. a four-factorial, five-level ccd consisting of 10 experiments was performed in the present work, including two replications at the canter point [24]. flow rate and initial db15 concentrations were considered as the independent variables while db15 removal efficiency was considered as the responses. table 1. illustrate the parameters studied and their ranges. additionally, the anova parameters such as probability (pvalue) and fisher-test (f-value) were used to demonstrate how the parameters affect the responses [25]. the predicted r2 must be in reasonable agreement with the adjusted r2 to confirm that adjusted responses are in agreement with predicted one [26]. eq.1 state the polynomial equation suggested by the design software and it illustrates the relationship between the independents dependents variables [4]. 𝒚 = 𝜶ₒ + 𝜶𝟏 𝒙𝟏 + 𝜶𝟐 𝒙𝟐 + 𝜶𝟑 𝒙𝟑 + 𝜶𝟒 𝒙𝟒 + 𝜶𝟏𝟏 𝒙𝟏 𝟐 + 𝜶𝟐𝟐 𝒙𝟐 𝟐 + 𝜶𝟑𝟑 𝒙𝟑 𝟐 + 𝜶𝟒𝟒 𝒙𝟒 𝟐 + 𝜶𝟏𝟐 𝒙𝟏𝒙𝟐 + 𝜶𝟏𝟑 𝒙𝟏𝒙𝟑 + 𝜶𝟏𝟒 𝒙𝟏𝒙𝟒 + 𝜶𝟐𝟑 𝒙𝟐𝒙𝟑 + 𝜶𝟐𝟒 𝒙𝟐𝒙𝟒 …(𝟏) where y is the response, αₒ is the constant of the regression equation, α1, α2, α3, α4 is linear coefficients, α12, α13, α23, α24, β14 is the interaction coefficients, (α11, α22, α33, α44) is the quadratic coefficients and x1, x2, x3, x4 are the independent variables. zainab a. mahmoud al-khwarizmi engineering journal, vol. 18, no. 4, p.p. 1431 (2022) 19 table 2, ranges and levels of parameters studied through continues photo-fenton-like process 2.7.fixed-bed results analysis the removal efficiency in fixed-bed design is assess from breakthrough curve. the breakthrough curve involves drawing of time against ratio of initial db15 concentration to outlet concentration (ct/ co). the other important parameter that obtained from breakthrough curve is breakthrough time (tb) is the time require for the effluent to reach 0.05 of the initial dye concentration [27]. moreover, the treatment process stopped when the ratio of ct/co reached 0.9 and the time at this point called execution time (te) [29]. in addition, the total amount of dye removed by the fixed-bed column could be estimated graphically from the area above the breakthrough curve as given in eq. 3 [27]. 𝑞𝑡𝑜𝑡𝑎𝑙 = 𝑄𝐴 1000 = 𝑄𝐶𝑜 1000 ∫ 𝐶𝑡 𝐶𝑜 𝑑𝑡 𝑡𝑠 𝑡=0 … (2) where a is the area above the curve, q is the flow rate of contaminant solution (ml/min), co and ct are the initial dye concentration and outlet dye concentration (mg/l) respectively, and ts is saturation time. 𝑚𝑡𝑜𝑡𝑎𝑙 = 𝐶𝑜𝑄𝑡𝑠 1000 … (3) 𝑅𝐸% = 𝑞𝑡𝑜𝑡𝑎𝑙 𝑚𝑡𝑜𝑡𝑎𝑙 ∗ 100 … (4) mtotal represent the total amount of contaminant entering the column and re% is the total removal efficiency [30] 3. results and dissection 3.1. characterization of e@b-fe/cu-nps the sem analysis of e@b-fe/cu-nps shown in figure 4 revealed that the nps had a spherical shape and porous surface, with a diameter of approximately from (34.39-72.40nm). furthermore, the uniform distribution of nps on the surface of bentonite is demonstrated, which prevents np agglomeration [31]. furthermore, the edax analysis revealed the constituents and chemical constituents of e@bfe/cu-nps. edax analysis revealed peaks of si, fe, cu, c, o, na, mg al, ca, and s, as shown in figure 5. c and o, on the other hand, were referring to the existence of polyphenolic compounds and other organic matter in eucalyptus leaf extract [32]. furthermore, the peaks si, mg, al, na, ca , and s appeared as a result of the nps being supported by the calcium bentonite clay [31]. fig. 4. the sem of e@b-fe/cu-nps. parameters ranges and levels -α low (-1) middle (0) +α high (+1) flow rate (ml/min) 0.172 1 3 5.829 5 db15 concentration mg/l 9.466 25 62.5 115.533 100 zainab a. mahmoud al-khwarizmi engineering journal, vol. 18, no. 4, p.p. 1431 (2022) 20 fig. 5. the eadx analysis of e@b-fe/cu-nps. the surface charge of nps in collide suspension were characterized using zp measurement. in the zp analysis ,a sharp peak at -73.52 mv was obtained as clarified in figure 6. fig. 6. zeta potential of e@b-fe/cu-nps. it is observed that the surface of the nps is negatively charged and dispersed in the medium. the high negative value confirms the repulsion among the particles, preventing the agglomeration of nps and proving that nps are very stable [33]. the stability of prepared catalyst is due to coating of nps surface with polyphenol present in eucalyptus leaves [34]. the surface roughness is one of the important features required in catalysts to improve the the 7 figureas shown in . 2o2catalytic process of h high roughness can be seen on nps surface [35]. moreover, the nps size ranged between (28-96 nm). zainab a. mahmoud al-khwarizmi engineering journal, vol. 18, no. 4, p.p. 1431 (2022) 21 fig. 7. atomic force microscopy (afm) characterization of e@b-fe/cu-nps. 3.2. statistical analysis of continuous fixedbed column containing gb-e@b-fe/cu-nps table 3 lists the adjusted and predicted responses. these data were compared and analysed statistically by the ccd. the results in table 4 indicates the predicted responses are compatible with adjusted responses because the difference between predicted r2 and adjusted r2 is less than 0.2 [1]. figure 8 gives an evident for compatibility between these two responses. fig. 8. actual versus predicted responses of gb-e@b-fe/cu-nps experiments. p-value is less than 5% indicates model terms are significant and as f-value increases the terms become more affected. as given in anova analysis (table 4), the p-value of flow rate was <0.0001and f-value of 1446.39 indicate that flow rate has a significant effect on response and it more affected than db15 concentration [26]. interaction effect between flow rate and db15 concentration gas a significant effect on responses. in addition, the regression coefficient of the quadratic model was (0.998) which indicates that the quadratic model well matches continuous photo-fenton-like experiments [4]. the anova analysis illustrated that the f-value and p-value of the model were 391.08 and < 0.0001, respectively, which indicates the model is significant. the quadratic model for db15 removal obtained through continuous photo-fenton-like experiments is given in eq. 5. %𝐷𝑅 = 69.5 − 9.6𝐴 + 1.88𝐵 − 6.5𝐴𝐵 − 2.81𝐴2 + 0.9375𝐵2 … (5) zainab a. mahmoud al-khwarizmi engineering journal, vol. 18, no. 4, p.p. 1431 (2022) 22 table 3, actual and predicted responses of continuous fixed-bed column containing gb-e@b-fe/cu-nps. run a:flow rate (ml/min) b:db15 concentration (mg/l) actual responses (%) predicted response (%) 1 3 115.533 74 74.04 2 5.82843 62.5 51 50.30 3 3 9.46699 69 68.71 4 0.171573 62.5 77 77.45 5 3 62.5 69 69.50 6 1 100 86 85.61 7 3 62.5 70 69.50 8 5 100 53 53.41 9 1 25 69 68.84 10 5 25 62 62.64 table 4, anova for quadratic model of fixed-bed column containing gb-e@b-fe/cu-nps. source sum of squares df mean square f-value p-value comments model 995.96 5 199.19 391.08 < 0.0001 significant a-flow rate 736.70 1 736.70 1446.39 < 0.0001 b-db15 concentration 28.39 1 28.39 55.74 0.0017 ab 169.00 1 169.00 331.81 < 0.0001 a² 36.16 1 36.16 71.00 0.0011 b² 4.02 1 4.02 7.89 0.0484 residual 2.04 4 0.5093 lack of fit 1.54 3 0.5124 1.02 0.6039 not significant pure error 0.5000 1 0.5000 cor total 998.00 9 r2 0.998 adjusted r2 0.995 predicted r2 0.987 adeq. precision 63.857 std.dev. 0.7137 3.3.effect of parameters on continuous fixed-bed experiments using gb-e@bfe/cu-nps 3.3.1. interaction effect between flow rate and db15 concentration according to figure 9, increasing the flow rate from 1 to 5 ml/min led to decreasing the removal efficiency. also, table 5 shows that the breakthrough time tb, saturation time ts and execution time te increased with increasing the flow rate. this phenomena occur, due to increasing residence time of contaminant in the column with decreasing flow rate [36]. furthermore, as db15 concentration risen from 25 to 100 mg/l, tb, ts, and te decreased. this happens because dye molecules obstruct the catalytic process of h2o2 by blocking catalyst pores and thereby preventing the formation of •oh. despite using the same amount of h2o2, when the db15 concentration was 25 mg/l, the ratio of •oh to initial db15 concentration was greater, indicating strong removal efficiency and a longer breakthrough time. this helps to explain why low initial db15 concentrations have a longer breakthrough time and a high removal efficiency [37]. figures 10 and 11 depict the breakthrough curves. zainab a. mahmoud al-khwarizmi engineering journal, vol. 18, no. 4, p.p. 1431 (2022) 23 fig. 9. (a) contour plot (b) 3dsurface of fixed-bed column containing gb-e@b-fe/cu-nps. fig. 10. the breakthrough carves at constants db15 concentration of 626.5 mg/l for fixed-bed column containing gb-e@b-fe/cu-nps. fig. 11. the breakthrough carves at constants flow rate of 5 ml/min for fixed-bed column containing gb-e@bfe/cu-nps. zainab a. mahmoud al-khwarizmi engineering journal, vol. 18, no. 4, p.p. 1431 (2022) 24 table 5, the results of breakthrough curve for fixed-bed column containing gb-e@b-fe/cu-nps. exp. no. a: flow rate ml/min b:db15 concentration mg/l dr % mtotal mg qtotal mg tb min ts min te min 1 3 115.533 74 95.497 70.924 28.3 132.6 179.3 2 5.82843 62.5 51 49.88 25.503 38 97.4 190.5 3 3 9.46699 69 3.618 2.477 122.1 175.3 255.6 4 0.171573 62.5 77 2.873 2.22 162.3 287 371.1 5 3 62.5 69 31.841 21.873 42.6 161.5 235.1 6 1 100 86 22.109 19.612 96.4 277.3 312.6 7 3 62.5 70 31.57 22.252 44.1 164.3 233.1 8 5 100 53 60.54 32.038 26.1 90.6 171.2 9 1 25 69 6.428 4.45 155.7 254.8 368.1 10 5 25 62 11 17.68 48.9 126.3 202.5 3.4.statistical analysis of continuous fixedbed column containing glass beadse@b-fe/cu-nps table 6 lists the adjusted and predicted responses obtaining fixed-bed experiments. these data were compared and analysed statistically by the ccd. the anova analysis (table 7) indicates the predicted responses are compatible with adjusted responses with predicted r2 and adjusted r2 were 0.988 and 0.974, respectively. figure 12 gives an evident for compatibility between these two responses. fig. 12. actual versus predicted responses for fixed-bed glass beads-e-fe/cu@b-np table 6, adjusted and predicted responses obtaining from fixed-bed glass beads-e@b-fe/cu-nps run a:flow rate (ml/min) b:dye concentration (mg/l) adjusted response (%) predicted response (%) 1 5 100 49 48.79 2 3 62.5 60 59.20 3 3 62.5 58.4 59.20 4 1 25 63 63.21 5 3 115.533 47 46.99 6 5.82843 62.5 49 49.31 7 5 25 52 51.78 8 0.171573 62.5 58 57.69 9 3 9.46699 59 59.01 10 1 100 49 49.22 zainab a. mahmoud al-khwarizmi engineering journal, vol. 18, no. 4, p.p. 1431 (2022) 25 table 7, anova for quadratic model of fixed-bed glass beads-e@b-fe/cu-nps. source sum of squares df mean square f-value p-value model 301.77 5 60.35 146.02 0.0001 significant a-flow rate 70.38 1 70.38 170.27 0.0002 b-dye concentration 144.25 1 144.25 348.99 < 0.0001 ab 30.25 1 30.25 73.19 0.0010 a² 37.13 1 37.13 89.83 0.0007 b² 43.93 1 43.93 106.29 0.0005 residual 1.65 4 0.4133 lack of fit 0.3733 3 0.1244 0.0972 0.9509 not significant pure error 1.28 1 1.28 cor total 303.42 9 r2 0.995 adjusted r2 0.988 predicted r2 0.974 adeq. precision 32.56 std. dev. 0.643 in this experiments, db15 concentration exhibit higher effect on response than flow rate with pvalue and f-value of <0.0001 and 348.99 while the p-value and f-value of flow rate were 0.0002 and 170.27. in addition, the quadratic model well matches continuous photo-fenton-like experiments using glass beads with regression coefficient of 0.995. the anova analysis illustrated that the f-value and p-value of the model were 146.02 and < 0.0001, respectively, which indicates the model is significant. the quadratic model for db15 removal obtained through continuous fixed-bed experiments is given in eq. 6 %𝐷𝑅 = 59.2 − 2.97 𝐴 − 4.25𝐵 + 2.75𝐴𝐵 − 2.85𝐴2 − 3.1𝐵2 … (6) 2.1. effect on parameters on continuous fixed-b-ed experiments containing glass beadse@b-fe/cu-nps 2.1.1. interaction effect between flow rate and db15 concentration in fixed-bed experiments packed with glass beads and e@b-fe/cu-nps, the db15 concentration exhibited a greater influence as compared to the experiments carried out in column packed with bentonite and e@b-fe/cu-nps, where flow rate showed a substantial impact on the removal efficiency. furthermore, table 8 and table 5 shows 47 % and 74% removal efficiency at flow rate 3ml/min, db15 concentration 115.553 mg/l for glass beads and bentonite experiment respectively. otherwise, the removal efficiencies in both experiments were almost similar at low dye concentration (25 mg/l) which meanes removal efficiencies were similar at low dye concentration (25 mg/l) whereas a great difference obtained when the dye concentration reached to 100 mg/l). these phenomena occur because in fixed-bed containing bentonite two processes happened (adoration and photo-fenton-like experiments) while only photo-fenton-like process occur in column packed with glass beads. figure 13 illustrate the interaction effect of flow rate and db15 concentration fixed-bed glass beads-e@bfe/cu-nps. figure 14 and figure 15 illustrate the breakthrough carves for fixed-bed containing glass beads-e@b-fe/cu-nps zainab a. mahmoud al-khwarizmi engineering journal, vol. 18, no. 4, p.p. 1431 (2022) 26 fig. 13. (a) contour plot (b) 3d surface of fixed-bed glass beads-e@b-fe/cu-nps. fig. 14. the breakthrough carves at constants db15 concentration of 626.5 mg/l for fixed-bed column containing glass beads-e@b-fe/cu-nps. fig. 15. the breakthrough carves at constants flow rate of 5 ml/min for fixed-bed column containing glass beadse@b-fe/cu-nps. zainab a. mahmoud al-khwarizmi engineering journal, vol. 18, no. 4, p.p. 1431 (2022) 27 table 8, breakthrough results obtaining from fixed-bed glass beads-e@b-fe/cu-nps 3.5. optimization of fixed-bed experiments following ccd analysis of the experimental data, the parameters that give the maximum db15 removal were found, and they are listed in table 9. table 9, optimum condition obtained from ccd for fixed-bed containing gb-e@b-fe/cu-nps glass beads-e@b-fe/cunps experiments. 4. conclusion the characterization results of prepared nanoparticles (e@b-fe/cu-nps) showed that e@b-fe/cu-nps had a spherical shape and porous surface. a zeta potential of -73.25 mv. the e@bfe/cu-nps surfaces exhibited high roughness. the resultant nps were used in db15 degradation through continuous photo-fenton-like process experiments using a fixed-bed column. two sets of experiments were designed through central composite design ccd to examine the db15 degradation through the continuous photo-fentonlike process using a fixed-bed column. one set involved packing the column with granular bentonite and e@b-fe/cu-nps (gb-fe/cu@bnps), and the other involved mixing the same catalysts with glass beads (glass beads-fe/cu@bnps). for gb-fe/cu@b-nps experiments, 94.213 mg/l of db15 was degraded by 81 % at a flow rate of 1.587 ml/min. the quadratic model describes the effect of parameters on db15 degradation is given in the equation below. %𝐷𝑅 = 69.5 − 9.6𝐴 + 1.88𝐵 − 6.5𝐴𝐵 − 2.81𝐴2 + 0.9375𝐵2 on the other hand, the fixed-bed containing glass beads-fe/cu@b-nps exhibited lower db15 removal efficiency (62.6 % at a flow rate of 1.064 ml/min and db15 38.37 mg/l) with the quadratic model given in the following equation. %𝐷𝑅 = 59.2 − 2.97 𝐴 − 4.25𝐵 + 2.75𝐴𝐵 − 2.85𝐴2 − 3.1𝐵2 acknowledgements the authors are very thankful to the alkhwarizmi college of engineering at the university of baghdad, iraq, and the environment and water directorate of the ministry of science and technology, iraq, for providing all the facilities to complete this research. exp. no. a: flow rate ml/min b:db15 concentration mg/l dr % mtotal mg qtotal mg tb min ts min te min 1 5 100 49 33.56 16.427 12 46.5 95 2 3 62.5 60 14.464 8.668 23.6 64 106.8 3 3 62.5 58.4 14.519 8.37 22.4 61.8 107.2 4 1 25 63 6.832 4.324 98.7 181.6 286.3 5 3 115.533 47 22.795 10.825 14.2 41.2 87.6 6 5.82843 62.5 49 27.941 13.734 14.5 52.3 106.2 7 5 25 52 11.028 5.789 21 66.3 126.2 8 0.171573 62.5 58 2.871 1.789 95.8 166.2 287.1 9 3 9.46699 59 3.579 2.122 42.1 98.6 166.3 10 1 100 49 8.338 4.109 37.1 75.2 152.6 parameters flow rate (ml/min) db15 concentration (mg/l) removal efficiency (%) fixed bed packed with bentonite and e@b-fe/cu-nps optimum condition 1.587 94.213 81.024 fixed bed packed with glass beads and e@b-fe/cu-nps optimum condition 1.064 38.37 62.562 zainab a. mahmoud al-khwarizmi engineering journal, vol. 18, no. 4, p.p. 1431 (2022) 28 5. references [1] q. zhao, j. f. kennedy, x. wang, x. yuan, and b. zhao, “optimization of ultrasonic circulating extraction of polysaccharides from asparagus officinalis using response surface methodology,” int. j. biol. macromol., vol. 49, no. 2, pp. 181–187, 2011, doi: 10.1016/j.ijbiomac.2011.04.012. 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(2022) 14-31، صفحة 4العدد، 18مجلة الخوارزمي الهندسية المجلد زينب عادل محمود 31 (photo-fenton-like)تأثير المادة الداعمة على تحطيم صبغة االزو بواسطة عملية الحشوة الثابتةوباستخدام العمود المتسمر ذو ***احمد خضير حسان **محمد عبد عطية السراج* زينب عادل محمود العراقكلية الهندسة الخوارزمي/ جامعة بغداد/ قسم الهندسة الكيميائية االحيائية/ *،** العراقوزارة العلوم والتكنولوجيا / دائرة بحوث البيئة والمياه/ ** الخالصة المعروفة باسم لمعالجة مياه الصرف الصحي الملوثة بصبغة زرقاء (photo-fenton-like)نظام الدفعات المستمرة وعملية اماستخدفي هذا الدراسة تم (direct blue 15) .يت اطين البنتونوتم تحميلها على من الحديد / النحاس ثنائية المعدن تم استخدام مستخلص أوراق األوكالبتوس إلنشاء جسيمات نانوية المحفز واستخدامه يت الحبيبي مع ا. األول يتضمن خلط البنتونالثابتة من العمود ذو الحشوة تمت دراسة ومقارنة تكوينين. الستخدامها كمحفزات غير متجانسة ذلك المسح المجهري الناتجة، بما في النانوية تم تطبيق طرق التوصيف على الجسيمات الزجاجية.المحفز مع الخرز خلط تضمنواآلخر ،كحشوة للعمود الصبغة تأثير العوامل الرئيسية على التحلل دراسة(. تم afm، وتقنيات التحليل الطيفي للقوى الذرية )(zeta potentialزيتا )وإمكانات ،semاإللكتروني كال النظامين ل لمعرفة الظروف المثلى( ccdالمركزي ). تم استخدام منهجية سطح االستجابة القائمة على التصميم المركب الصبغةوتركيز التدفق،معدل اهمها في العمود الذي يحتوي على ٪ 62.6و في العمود الذي يحتوي على حبيبات البنتونايت مع المحفز٪ 81المدروسين. أظهرت النتائج أن كفاءة اإلزالة كانت .الخرز الزجاجية مع المحفز table 6, adjusted and predicted responses obtaining from fixed-bed glass beads-e@b-fe/cu-nps this is an open access article under the cc by license : al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 21, no. 3, september, (2025), pp. 7696 impact of design parameters in thermal solar water storage tank systems: (a review) narjes ahmed hussain1*, and karima e. amori2 1 department of mechanical engineering, college of engineering, university of baghdad, baghdad, iraq 2mcf-hdr à polytech nancy, université de lorraine, recherche au lemta,umr cnrs-ul, 2 rue jean lamour f54500 vandoeuvre-lès-nancy, france *corresponding author’s email: n.ahmed1703@coeng.uobaghdad.edu.iq (received 24 june 2024; revised 10 january 2025; accepted 25 february 2025; published 1 september 2025) https://doi.org/10.22153/kej.2025.02.005 abstract this work provides a historical overview of water storage tanks used for solar energy collection, with a focus on the impact of different geometric configurations on thermal performance and energy storage efficiency. the designs of cylindrical, spherical, rectangular and triangular tanks were reviewed to analyse their effects on thermal gradients, heat retention and energy storage capacity. within the scope of nominal processes, the study primarily aimed to identify the factors influencing the choice of tank shape in terms of size, capacity and aspect ratio. another key objective was to assess what enhances heat storage in the tank to improve thermal efficiency. comparing cylindrical shapes to other shapes, such as spherical, rectangular, and triangular , it offered the optimal performance with the needed requirements for the objects that have a smaller surface area-to-capacity ratio in addition to the lower heat loss. furthermore,when the tilt angle with horizontal axes of the storage tank was at 0°, the tanks’ ratio reduction had remarkable impact on thermal stratification . the results might provide valuable information for the thermal storage system’sdesign in solar water heating for improving thermal efficiency. this work provides the basis for research exploiting high-temperature solar energy storage technologies and their applications in building sustainable energy systems. keywords: thermal stratification ,solar thermal system;; water tank; geometric design; n; insulation cover. 1. introduction with increasing demands for sustainable energy resources and the rapid development of novel solar thermal technologies. ,these resources and technologies have been used widly in building and industrial heating application of the on roof integrated solar collector water storage systems. for example, the fluid circulation for linking all devices is reduced since collectors and storage tanks form a proper single component [1]. comparing with traditional designs, it has been recognized many pros of the integral systems, such as a space saving and better general feasibility. to illustrate, system performance depends on a number of parameters as the geometry of the combined storage tank is one of them. as a matter of fact,the tank geometry is a main factor to achieve the maximum thermal performance which influences ultimately on the thermal stratification,the heat retention time (usability) and the overall energy gain. to maximize the potential of the incoming solar energy,the thermal stratification should be well achieved in order to keep the hot water at the top of the tank and cold make-up water is delivered at the bottom, [2]. whilst previous studies have explored various aspects of solar thermal systems, such as material properties, insulation techniques and fluid dynamics, the influence of tank geometry on thermal performance has not been comprehensively addressed. https://doi.org/10.22153/kej.2025.02.005 https://doi.org/10.22153/kej.2025.02.005 narjes ahmed hussain al-khwarizmi engineering journal, vol. 21, no.3, pp. 7696 (2025) 77 the present work aims to highlight the influence of tank geometry on energy storage, water depth and overall thermal efficiency within an integrated solar collector water storage tank (iscwst) device. by reviewing studies that combine computational fluid dynamics (cfd) simulations with experimental analyses, the thermal performance of cylindrical, spherical, rectangular and triangular-shaped tanks is examined. key parameters such as temperature distribution, heat loss rates and overall energy storage efficiency under typical operating conditions provide valuable insights for optimising solar storage systems. one of the main challenges to maintaining thermal stratification is the load profile of the system and the nature of water withdrawal— whether continuous or intermittent. additionally, the temperature of incoming freshwater, which is beyond control, notably influences system thermal performance during the charging heat (daytime heating). notably, thermal stratification tends to be enhanced during the day when solar energy is available, whilst after sunset, the tank gradually begins to lose a portion of its stored heat. the findings of this study aim to support broader adoption of solar water heating systems by promoting cost-effective and efficient solutions accessible to a larger segment of households. furthermore, the study offers guidance on optimal task design to maximise the use of solar radiation as a renewable energy source. additionally, the study outlines a systematic design approach for thermal water storage tanks in solar systems, intended to benefit future generations of solar energy technologies. 2. solar collector water storage tank history the concept of using solar energy for water heating dates back to ancient civilisations. the greeks and romans employed solar architecture techniques to warm their homes and public baths, establishing the foundational principles of solar water heating [3]. the modern era of solar water heating began in the late 19th and early 20th centuries. in 1891, clarence kemp of baltimore patented the first commercial solar water heater, known as the ‘climax’ solar water heater. as described by belessiotis and papanicolaou [4], this device featured a black-painted tank exposed to sunlight to heat water, making a considerable advancement in the practical use of solar energy. fig. 1. first commercial solar water heater [4] kemp’s invention sparked widespread interest and laid the groundwork for highly advanced solar thermal systems. kemp also patented the first commercial solar water heater enclosed in a wooden box, as shown in figure 1, effectively creating what is currently known as the first ‘batch water heater’. during the 1920s and 1930s, solar water heaters gained popularity in the united states, particularly in sunny states such as florida and california [5]. these early systems typically featured a black-painted metal tank mounted on rooftops, which absorbed solar radiation and transferred the heat to the water inside. however, the rise of cheap fossil fuels and the growing convenience of electric and gas water heaters led to a remarkable decline in the use of solar water heaters by the mid-20th century. the energy crisis of the 1970s reignited global interest in renewable energy sources, including solar thermal systems. this period also marked considerable improvements in solar collector technology, particularly the development of flatplate and evacuated tube collectors [6]. known for their ‘improved efficiency’ in capturing solar energy, these collectors notably enhanced overall system performance when paired with wellinsulated storage tanks. in the decades following the 1980s, research and development in solar thermal technologies, particularly low-temperature systems, provide notable contributions to sustainable solutions for hot water production and space heating. these advancements led to the creation of specially engineered systems designed for greater efficiency and practicality. over time, researchers developed automatic solar collectors integrated with water storage tanks to enhance the performance of solar narjes ahmed hussain al-khwarizmi engineering journal, vol. 21, no.3, pp. 7696 (2025) 78 water heating systems. these integrated devices combine necessary functions for thermal energy collection and storage into a single, compact unit. mirunalini et al. [7] developed a simple and low-cost integrated system that minimises heat losses from a newly designed cylindrical tank, coupled with an improved matching collector.. recently, new technologies, such as advanced surface coatings, high-quality insulation, and improved tank designs, have made these systems more reliable and productive. more than 600 projects worldwide have utilized domestic, commercial and industrial scale tank systems with i solar collectors integration. these systems play a crucial role in supporting the global transition from fossil fuels to alternative, renewable energy sources. as technology continues to evolve, ongoing research focused on performance improvements and cost reductions will help ensure that solar thermal systems remain a key contributor to global energy sustainability [8]. 3. solar water heating (swh) system main components the primary applications of solar water heating (swh) include domestic water heating (which is the focus of this research), swimming pool heating and various high-temperature applications. a typically solar water heating system comprises solar collectors, a storage tank, heat transfer fluid, a backup water heater, pipelines, controls and valves. the storage tank is equipped with pressure relief valves to ensure safety, and the system allows for the isolation of solar collectors when necessary. additionally, air vents are installed at the highest points in the piping to release trapped air and maintain system efficiency. 3.1. swh collectors these devices capture and concentrate solar energy within tubes that contain a circulating heat transfer fluid. solar water heater collectors are mainly divided into the following categories tailored for the described key applications: glazed flat-plate collectors, unglazed flat-plate collectors, evacuated tube collectors, parabolic trough collectors, integrated collector storage systems and thermosiphon systems, as shown in figure 2 (a, b, c, d, e, f). 3.2. heat transfer fluid the heat transfer fluid used in solar water heating systems can be either potable water in direct systems or an antifreeze solution in indirect systems. antifreeze is crucial in areas with freezing temperatures; otherwise, the system must be shut down and drained during winter to prevent damage. consequently, indirect systems are commonly used in such climates. antifreeze formulations typically include either propylene glycol or ethylene glycol, which is hazardous. the us food and drug administration has classified propylene glycol as ‘generally recognised as safe’ for use in foodrelated applications. consequently, a mixture of propylene glycol and water is the primary antifreeze solution used in solar hot water systems. 3.3. water storage tank the storage tank holds water heated by the solar collectors. in some systems, the collectors may also be integrated with tanks that activate heat exchangers and (or) provide supplementary water heating functionality. the required tank size is determined by the volume and duration of hot water demand, as well as the system’s capacity for hot water production. a dedicated solar water tank typically offers better performance compared to a traditional water heater. in systems that use a single tank, a split configuration is recommended to optimise thermal performance and reduce necessary heat loss to the solar array. section 4 discusses various tank shapes in detail. 3.4. connected pipes the water or antifreeze solution circulates through pipelines connecting the solar collectors, tank(s) and end users. copper piping is typically used between the collectors and the storage tank due to its durability and heat resistance. in contrast, pvc or cross-linked polyethylene is commonly used for piping between the storage tank, auxiliary water heater (if present) and the end users. narjes ahmed hussain al-khwarizmi engineering journal, vol. 21, no.3, pp. 7696 (2025) 79 fig. 2. solar water heater, a) flat-plate, glazed solar hot water collector, b) flat-plate, unglazed solar hot water collector, c) evacuated tube collector, d) parabolic trough collector, e) integral collector/storage system, f) thermosiphon system [9] (a) (b) (c) (f) (e) (d) narjes ahmed hussain al-khwarizmi engineering journal, vol. 21, no.3, pp. 7696 (2025) 80 3.5. control system automatic or manual valves are used to activate, deactivate or divert the flow within solar water heating systems. additionally, a safety pressure release valve is included to prevent overpressure conditions. 4. shape of the solar water storage tank the shape of the water tank plays a crucial role in determining the thermal efficiency and energy storage capacity of an integrated solar energy system. key characteristics, such as the temperature distribution within heat-producing layers and the surface area exposed to solar radiation, are heavily influenced by the tank’s geometry and overall engineering design, both of which notably affect system performance. this section explores the effect of various tank shapes on thermal behaviour, beginning with cylindrical and spherical configurations and concluding with triangular and rectangular tank designs. 4.1. cylindrical tanks structurally, one of the most common shapes in solar water heating systems is the cylinder tank, valued for its high structural efficiency and ease of manufacturing. arslan and igci [10] developed a performance modelling for vertical cylindrical tanks equipped with a mantle heat exchanger, evaluating their thermal performance during discharging and consumption modes. aiming to improve thermal stratification and optimise performance parameters, a three-dimensional transient cfd simulation was employed to analyse the flow and thermal fields within the mantle solar storage tanks. the study found that high fluid temperatures flowing through the mantle heat exchanger notably improved thermal stratification within the tank. fig. 3. solar water heater system [9] a higher grashof number enhances the tank’s thermal performance by promoting natural convection. however, extended discharge times can reduce the tank’s capability to consistently supply hot water for consumption. several figures illustrate the enhancement of natural thermal stratification, in which hot water rises to the top whilst cold water settles at the bottom, as depicted in figure 3. this stratification is necessary for maintaining a sufficiently high temperature at the point of use. narjes ahmed hussain al-khwarizmi engineering journal, vol. 21, no.3, pp. 7696 (2025) 81 fig. 4. temperature contours (above) and stream wise (below) inside the tank for higher grashof number [10] madhlopa et al. [11] conducted an experimental study on the influence of surface pipe configuration on water temperature stratification in an integrated solar collector system using two horizontal cylindrical tanks. the experiment evaluated three modes of operation: a connected p-tank, an s1-tank and an s2-tank interconnection. the tanks were interconnected using insulated hose pipes (ihp) with a diameter of 12.7 mm, arranged in parallel for the p-tank configuration, in series with one ihp for the s1-tank interconnection and in series with two ihps for the s2-tank. these connections linked the lower and upper tanks, as shown in figure 5. fig. 5. water flow pattern details for a) p, b) s1, c) s2-tank connections [11] during heat charging, the lower tank displayed temperature stratification, whereas the upper tank did not. in the s2-tank mode, both tanks demonstrated satisfactory stratification. the s1tank mode is suitable for a double-tank icsswh when the water temperature is expected to be equal to or less than that of the upper tank, as well as in configurations that rely on an inter-tank thermosiphon for natural fluid circulation. figure 6 shows a designed icssw system featuring two cylindrical galvanised iron tanks, each with a capacity of 61.8 l. the upper tank is insulated with waste cotton, whilst the lower tank is covered with clear glass to allow the entry of solar radiation. the system is designed to absorb most of the reflected beam radiation at normal incidence angles, with radiation losses peaking in june. the lower tank and its wide acceptance angle enable substantial capture of incident diffused radiation. narjes ahmed hussain al-khwarizmi engineering journal, vol. 21, no.3, pp. 7696 (2025) 82 fig. 6. schematic presentation of an iscwst showing the following: a) perspective view, b) cross-section of the system with aa´ = 0.940 m, a ´ be´ = parabolic section, ob = focal length of the parabola (0.711 m), ee´ = vertical section (0.705 m), b = the vertex of the parabola [11] yu et al. [12] proposed a new structure for cylindrical hot water tanks by placing phase change material (pcm) on the tank side, addressing the issue of limited hot water capacity. domestic hot water tanks often integrate pcms at the top due to their potential to increase thermal storage density. experiments were conducted on a 150 l cylindrical hot water tank to evaluate its thermal performance and analyse the impact of thermal gradients when using materials with latent heat. the use of polyurethane foam insulation substantially enhanced the thermal performance of the cylindrical hot water tank, extending the cooling time from 65 °c to 40 °c. the concentration and location of pcm also influenced the thermal stratification within the tank. at ulster university, smyth et al. [13] developed new prototypes of low-pressure horizontal cylindrical solar water heating systems, as shown in figure 6, featuring a patented double thermosiphon container. simple and inexpensive icsswt systems were constructed using open water tanks painted black and exposed directly to sunlight. an energy performance assessment was conducted, and the designs of various prototypes were evaluated under experimental conditions simulating solar radiation. the study demonstrated that design changes, such as buried welded final covers, transparent covers, targeted insulation and sealing of final cover fittings, can substantially enhance the performance of solar water heating systems. the improved model achieved a daily efficiency of 22% over 24 h, was simple to install and was suitable for large-scale production at a reasonable cost, particularly for use in developing countries. gao et al. [14] conducted a study to examine the effect of the initial temperature on the thermal gradient during the discharge mode of a vertical cylindrical hot water storage tank. digital data were used to analyse the tank’s typical solar characteristics. vertical cylindrical hot water storage tanks are widely used in practical applications, and in solar water heating tanks, the effects of the initial temperature on flow dynamics, heat distribution and thermal mixing mechanisms are thoroughly investigated. the physical experiment validates the simulation results by introducing non-dimensional energy and thermal layer thickness to assess the reservoir’s thermal gradient. the density difference between the hot and cold-water areas is more pronounced, indicating a notable thermal difference. this finding leads to a lower initial mixing level and a higher rate of hot water production. the hot water production rate increases by approximately 11% when the initial temperature is raised from 313k (40°c) to 353k (800°c). the non-dimensional average thickness of the thermal layer can be expressed as the thickness of the water's temperature transition zone, which decreases in parallel with the initial temperature. the initial temperature decreases significantly, from 313k to 333k. the degree of thermal differentiation linearly increases with the initial reservoir temperature and the non-dimensional time. a 0.3 increase in thermal differentiation represents more than 70% of the total improvement over the entire discharge period. when the initial temperature rises from 313k to 353k, the average dimensionless energy decreases from 0.46 to 0.29, resulting in a 17% increase in the thermal gradient. the cylindrical shape provides an optimal surfaceto-volume ratio, reducing heat loss through the tank walls. additionally, the design of cylindrical tanks facilitates efficient insulation and compact packaging, further reducing thermal losses. considering these characteristics, cfd simulations and experimental studies have shown that cylindrical tanks generally offer superior thermal performance compared to other shapes [15]. narjes ahmed hussain al-khwarizmi engineering journal, vol. 21, no.3, pp. 7696 (2025) 83 4.2. spherical tanks spherical tanks offer the best surface area-to volume ratio, theoretically reducing heat loss. however, their use in solar thermal systems remains limited. the spherical shape helps achieve more consistent temperature distribution within the tank because is allows for more even heat distribution and reduces thermal gradients that are often more noticeable in tanks with flat surfaces or boundaries. despite these advantages, the complexities of heat transfer within spherical tanks, along with the relatively limited effectiveness of convection currents compared to cylindrical tanks, makes this design less favourable for optimising thermal performance. fig. 7. spherical tanks [17] in contrast, spherical tanks can be valuable in certain situations where heating efficiency and limited horizontal space are notable concerns [16]. advanced manufacturing techniques and new materials may help overcome some of the practical limitations of spherical tanks, potentially making them a more viable option for specific applications. 4.3. rectangular tanks rectangular tanks, often chosen for their simplicity and ease of installation, exhibit different thermal characteristics. the flat surfaces of rectangular tanks can result in uneven temperature distribution and reduced thermal stratification, as demonstrated by chung et al. [18]. heat tends to escape readily from the corners and edges, leading to increased overall heat loss. rashidov et al. [19] developed a calculation model for the water distributor in a multi-layer thermal storage tank used in solar heating systems and hot water supply. they formulated a non-linear second-degree equation for fluid motion along the path, accounting for archimedean forces. a uniformly perforated water distributor with a constant crosssection is installed throughout the tank’s height. this design enables solar heating systems to achieve a substantial temperature gradient, with the upper layers of the thermal water storage tank being hotter than the lower layers. the layer-by-layer charging principle, which involves supplying hot water from the collector to the appropriate layer, is widely employed in solar-powered hot water supply and heating systems. considering the difficulty of achieving a good thermal gradient in storage tanks, the potential for increasing solar energy percentage is typically limited to no more than one-third of its value. a numerical solution has been developed to design self-organising active elements for temperature-based selective water distribution along the height of the layered assembly. agreement between the calculated and the experimental data has been confirmed. the model incorporates various factors such as water velocities, external flow velocities, distances from stop ends, nominal opening lengths, cross-sectional areas, hole areas, surrounding and dispersing water entities, density changes, friction coefficients, flow rate coefficients, gravitational acceleration, nominal opening parameters, water distributor parameters and the adjusted richardson number. however, rectangular tanks can offer advantages in situations with limited space or where a low-profile installation is necessary. enhancements, such as internal baffles, can improve thermal stratification and mitigate heat loss issues. additionally, modular designs facilitated by rectangular tanks are beneficial in large-scale solar thermal applications that require the connection of multiple units [20]. narjes ahmed hussain al-khwarizmi engineering journal, vol. 21, no.3, pp. 7696 (2025) 84 fig. 8. rectangular tanks [21] 4.4. triangular tanks the design and implementation of a triangular water storage tank integrated with a solar heating system is a novel approach to addressing the challenges of water storage and heating in remote or off-grid locations, as shown in figure 6. as the standard solar water heating systems generally have medium in cubic or circular storage, , the heat transfer and volume can be less effective according to abokersh et al. [51], the triangular tank for the ms storageand the three triangular tank structure for the ms tank can enhance heat transfer, thermal stratification limit footprint. therefore, the main goal of the triangular tank design is for its ability to lead to the transfer of heat through the entire body of water, maximizing efficiency. natural convicting currents will be formed as a result of the tank’s conical shape , through which the temperature distribution becomes more even and the heated water volume’s circulation is enhanced. research on this phenomenon has been conducted by by hudon and his colleagues as well [22]. to redistribute the co2, a series of triangles are aligned to attenuate uneven heating and uneven distribution, . because of an equal temperature distribution in the storage volume, it couldlead to an improved solar heating efficiency. the study results suggest that the triangular design provides superior in thermal aspect along with increasing storage capacity and reducingfootprint relative to regular rectangular or round tanks, this designoffers advantages in areas with limited roof and ground space. the application of a triangular shaped configuration has been examined for an integrated storage solar water heater as an alternative to the conventional rectangle design. the impact of the triangular shape on the heater efficiency and heat retention is analyzed by using mathematical modeling and experimental validation. triangular solar water heaters aim to improve heating and cooling efficiency. the results show that the heating rate is faster in sunlight compared to a rectangular tank. however, whilst night cooling is a key factor for these heaters, the study does not provide an explanation regarding the impact of the shape on the cooling process. suggested improvements include adding a second cover with an insulating baffle plate or applying a suitable coating to the absorber surface to minimise heat loss during the night [24]. badescu et al. [23] compared different tank shapes and found that cylindrical tanks are superior in terms of thermal efficiency but may be relatively impractical. whilst spherical tanks are tactically preferred for minimising total heat loss, they are difficult to construct and prone to stratification problems. rectangular tanks, though offering less surface area for heat transfer, allow for greater flexibility in design and installation. therefore, the thermal performance requirements and practical constraints must be considered when choosing tank geometry. cylindrical tanks typically prevail over other designs for integrated solar collector water storage due to their neat and compact design, favourable stratification properties and excellent thermal inertia. however, advancements in materials and fabrication techniques could make other shapes more practical, broadening the range of options available for designing solar thermal storage systems. narjes ahmed hussain al-khwarizmi engineering journal, vol. 21, no.3, pp. 7696 (2025) 85 fig. 9. triangular tanks [25] 5. influence of parameters on the selection of tank shape the following parameters influence the selection of the tank shape: 5.1. volume and capacity the capacity of storage tanks to produce and store thermal energy is a crucial parameter for the performance of solar energy collectors integrated with water. yari et al. [26] highlighted the importance of selecting an ideal tank size that allows it to fulfil its thermal duty without losing a considerable amount of collected solar energy. the study compared the tank’s capacity with the performance and efficiency of energy storage in a thermal tank’s solar collector, revealing that a larger tank capacity requires more intense solar radiation and a longer duration to heat the water inside. hidalgo et al. [27] conducted a study to investigate the relationship between the size of the solar water storage tank and the energy storage efficiency of the solar collector system. the study found that this relationship depends on multiple factors, including the size of the solar collector array, the expected demand for hot water and local climatic conditions, because weather patterns can notably vary from one place to another. thus, the previously mentioned thermal energy storage capacity can help alleviate pressure during peak demand periods, including cloudy days when solar radiation decreases. large tanks can store additional heat. however, increasing the tank size also leads to higher heat losses and greater costs, with no proportional increase in energy storage capacity. according to chang et al. [28], the ratio of reservoir volume to collector area is a critical governing parameter that must be considered in reservoir design. the tank can retain all the heat generated by the solar collectors with minimal loss, provided that this ratio is optimised through insulation, proper orientation of the solar collectors and several other factors mentioned in the next section of the research. typically, a storage capacity ranging from 50l to 75l per square metre of facility space yields the best results. this finding has been demonstrated by the icsswt facility on jeju island, south korea, which operates effectively during the winter season. this ratio ensures optimal energy storage without overloading the tank or the collector system. additionally, the study by villasmil et al. [29] emphasises the importance of isolating the reservoir, which plays a key role in determining the effective storage capacity. table 1, volume, capacity and surface area of geometric bodies’ relationship with different shapes. high-quality insulation is essential for reducing heat loss from the tank. this feature becomes particularly important when dealing with larger tanks or unexpected thermal leaks, especially when parameter cylinder d/h = 1 sphere rectangle triangle "v" volume (𝑚3) v = 𝐷2 4 × 𝜋 × 𝐻 v= 𝐷3 4 𝜋 v = 𝐷3 6 × 𝜋 v = 𝑎3 v = 1 2 × 𝑏 × 𝐻2 "a" surface area (𝑚2) a = 2 × 𝐷2 4 + 𝐷 × 𝜋 × 𝐻 when, 𝐻 = 3 2 × 𝐷2 × 𝜋 a = 𝐷2 × 𝜋 a = 6 𝑎 = 6 √𝑉 3 a = ( b × h ) + l × (𝑆1 + 𝑆2 + 𝐻) narjes ahmed hussain al-khwarizmi engineering journal, vol. 21, no.3, pp. 7696 (2025) 86 higher heat levels are required. as demand fluctuates over different seasons and days, high-capacity and energy-efficient reservoirs can be produced by using advanced insulation materials and methods. for example,, a bigger tank can generate sufficient heat during the shorter daylight hours of winter to ensure a continuous supply of hot water steam. however, during summer the solar tank could get excessively warm, making it necessary to prevent overheating or stagnation. while a big tank offers adequate storage capacity, practical considerations such as availability, infrastructure, make up and installation complexity. there is an inherent trade-off between the required tank size, thermal benefits and practicalities. to balance the benefits of big reservoirs and the installation and maintenance advantage , modular tanks that are interconnected through other smaller tanks were proposed [30]. the comparative approach in this section shows that the previous favourable state where either none or all present tanks have the desired gas levels is not universal and only a complementary result is directly yielded for tanks of various sizes or rectilinear dimensions. additionally, the optimal size of the tank depends heavily on the desired application and use, including anticipated hot water consumption and exact needs of the solar collector system. however, it is critical for the development of a solar heating system with an efficient energy storage the ratio of the volume of the tank to the collector area and the selection of insulation thickness . in general, the performance of a built-in solar collector water storage tank is influenced by both its size and capacity. there is a trade-off between the high thermal insulation requirement and the need to prevent the user from feeling through the thermal insulation. this balance must also account for installation limitations. advances in insulation and tank design have made it possible to create larger storage tanks, enhancing systems efficiency, and reducing the scale of the systems for more compact units which produce higher overall energy yields \. 5.2. aspect ratio (height to diameter ratio) aspect ratio (h/d), the ratio of height to diameter of a tank is another critical factor in the design of integrated solar collector water storage tanks. such balance is of great significance for the absorber considering its close connection and contribution to storage of solar heating energy, thermal stratification maintaining and heat storage, as a faulty aspect ratio can greatly decrease the efficiency of the absorber. different tank formations inhibit fluid flow and, consequently, heat loss from the tank’s walls, which, in turn, influences overall performance. this section investigates the effect of aspect ratios on the effectiveness of solar thermal storage systems [30]. aiming to calculate the aspect ratio, the length (l), width (w) and height (h) of the tank are measured. the aspect ratio is evaluated as follows: • length to width ratio: this is the most commonly used aspect ratio (l:w) = l/w • length to height ratio: useful in some contexts: aspect ratio (l:h) = l/h • width to height ratio: another perspective: aspect ratio (w:h) = w/h kurşun and ökten [31] conducted a numerical study to examine the effects of tank tilt angles relative to the horizontal axis (α) and the aspect ratios of the water tank. the numerical analyses were conducted within angle values ranging from 0° to 60° and aspect ratio values ranging from 0.5 to 1. the findings demonstrate that repositioning the hot water tank at various angles, such as α = 0°, improves thermal stratification. decreasing the aspect ratio of the tank substantially impacted thermal stratification only when the angle α equalled 0°. the most remarkable temperature differential in the hot water tank was observed at a tilt angle of α = 45° and an aspect ratio of d/h = 0.5. the following are classifications of aspect ratios: 5.2.1. high aspect ratio tanks with a high aspect ratio (taller height relative to diameter) are generally highly effective at promoting thermal stratification. the increased height allows for a more pronounced temperature gradient due to the greater vertical distance, allowing hot water to rise and cool water to sink. this configuration minimises mixing and maintains distinct thermal layers. high aspect ratio tanks are particularly advantageous in systems where maintaining a high outlet temperature is critical [32]. however, these tanks may require robust structural support and can be challenging to install in spaces with height limitations. additionally, the increased surface area of the tank walls can lead to high heat losses if inadequately insulated. garnire et al. [33] conducted an experimental and computational study of an icsswt using a high aspect ratio at edinburgh napier university during the winter. the effect of water withdrawal and the environmental impact on the design were analysed numerically. compared to previous research, the experimental results of the narjes ahmed hussain al-khwarizmi engineering journal, vol. 21, no.3, pp. 7696 (2025) 87 new icsswh collector show an increase in bulk temperature of 6.3 °c with a maximum and average percentage increase in temperature stratification of 67% and 133%, respectively, after 8 h of charging. however, the increased aspect ratio alters the heating and cooling characteristics of the swh, causing it to gain and lose heat at a greater rate than the original design. 5.2.2. low aspect ratio tanks according to çomakli et al. [34], tanks with a low aspect ratio (wider diameter relative to height) tend to have a more compact design, making installation in spaces with height restrictions easier. however, maintaining thermal stratification in these tanks can be highly challenging due to the short vertical distance. this configuration can lead to increased mixing of hot and cold water, reducing the effectiveness of the stratification. despite these challenges, low aspect ratio tanks can be beneficial in applications where space constraints are a primary concern. baffle or diffuser hole designs can also help promote stratification and reduce mixing. lowering the profile offers improved stability and easier insulation compared to taller, vertical-type tanks. 5.2.3. optimal aspect ratio ji et al. [35] optimised the aspect ratio ar to accomplish a suitable trade-off between the benefits of thermal stratification and the effortless installation, as well as structural considerations. many studies have found out that 2:1 (h:d) aspect ratio provides a practical compromise, positively promoting stratification while maintaining hands-on dimensions for installation and insulation. nonetheless, the optimal ar depends on a specified application requirements , preferred temperature behaviour, the volume of water to be stored, and the space available for installation.and the space available for installation). for example, a tank with a height of two meters and a diameter of one metre supplies adequate volume for effective stratification, along adequate surface area for heat absorption. the most effective method to determine the optimal aspect ratio is to combine cfd models with experimental tests according to each system and operating condition. comparison across different aspect ratios shows that higher aspect ratio tanks are generally achieve better thermal stratification, resulting in improved energy storage efficiency. . innovative designs and high-quality insulation can help address practical challenges related to installation and structural support, even though taller tank walls may increase heat loss. although low aspect ratio tanks are easy to install and insulate, achieving proper stratification often requires specific design considerations. lastly, the aspect ratio of ics water storage tanks is a key factor in determining their thermal performance and energy efficiency. optimizing this parameter allows designers to enhance their efficiency and effectiveness of solar thermal storage systems, contributing to more sustainable energy solutions [36]. 6. improving the efficiency of the thermal storage tank: 6.1. stratification one of the key factors affecting the energy storage efficiency of of integrated water storage tanks is the temperature gradient established within the tank. thermal tratification occurs when l layers of different temperatures are formed within the reservoir , heated water, being less dense, rises to the top, while cooler, denser water settles at the bottom as shown in figure 7. the temperature gradient between the water supply pipe and the discharge pipe affects maintaining hot water at the top for immediate use, while colder water at the bottom continue to be heated by the solar collector. this section explores the phenomenon of stratification, its impacts on system performance and improvements across various tank geometries. the storage capacity of available for installation proper arrangement of large tanks enhances stratification by offering a greater vertical volume which promotes the formation of thermocline cells in the thermal layers. although exposing the system to high value of heat increases stored thermal energy, it may extend longer to accomplish the correct temperature, potentially decreasing overall efficiency. according to han et al. [37], thermal stratification is critical requirements for optimal efficient solar thermal systems. system efficiency depends on sufficient heat mixing and insisting a considerable temperature difference between the inlet and the outlet. well stratified tanks specified by low energy requirement for water heating with low heat loss, can significantly improve overall system efficiency narjes ahmed hussain al-khwarizmi engineering journal, vol. 21, no.3, pp. 7696 (2025) 88 fig. 10. stratified storage tank [37] 6.1.1. factors influencing stratification tank geometry is considered main factor influencing the stratification within a water storage tank. the tank’s shape and ratio determine its thermal performance. tall and high-aspect-ratio tanks promote stronger stratification by allowing the formation of multiple thermal layers across a larger vertical volume.. selection of inlets and outlet’s locations and design are important to preserve stratification. a stable temperature variation along the tank height can be sustained by strategically positioning the inlets near the bottom to supply cold water and the outlets near the top to withdraw the hot water. the inflow and outflow patterns of water flow rates in and from the tank can either support or disrupt stratification..low flow rates generally boost stratification by minimising mixing. effective thermal insulation supports this process by minimizing heat losses and preserving distinct temperature gradients. incorporating internal baffles and well-designed diffusers can improve the thermal stratification by addressing the water flow into channels and preventing mixing of hot and cold layers. 6.1.2. enhancing stratification several approaches can be implemented toenhance stratification in the integrated solar collector water storage tank.. ● optimization of inlet configuration: this design can use diffusers or baffles at the inlet can enhance the uniform distribution of incoming cold water, thereby reducing turbulence, minimizing mixing, and promoting thermal stratification. ● layered inlets: installing multiple inlets located at different heights can promote feed water at specific temperature layers and maintainingstratification. ● flow control: the flow control technique delays water inflow and outflow from the tank, strengthening the temperature gradient. ● insulation techniques: advanced insulation materials and methods reduce the heat loss and sustaining’s the vertical temperature gradient. ● tank shape optimisation: according to kumar et al. [38] that selection of the appropriate tank shape and aspect ratio, inherently promotes stratification and enhance thermal performance eventually. to assess and develop tank performance,accurate stratification sensing and monitoring must be implemented temperature sensors with multi-level in the tank can provide a comprehensive data of the temperature gradient profile. to improve stratification, such as flow rates and inlet configurations , feedback received from these sensors can be employed for system parameter adjustment ● reviewing various tank designs options, when the tanks with high ratios are paired, with optimised inlet/outlet designs, exhibit superior thermal differentiation. rectangular tanks frequentaly maintain effective thermal layering and might require novel design features, barriers as an example to preserve stratification. in comparison withthe cylindrical and triangular tanks which are commonly more effective in maintaining thermal layers without the need auxiliary elements. although spherical tanks offer a hypothetical advantage for their minimal surface area-to-volume ratio, achieving and conserving the stratification within the layers is tough. the thermal gradient within the tank can affect the overall performance of water storage solar heating systems. the thermal performance and energy storage efficiency of solar heating systems can be significantly expanded by understanding the factors influencing the stratification and applying associated design methods into application. https://www.sciencedirect.com/topics/engineering/stratified-storage narjes ahmed hussain al-khwarizmi engineering journal, vol. 21, no.3, pp. 7696 (2025) 89 6.2. insulation insulation is a key element in iscwsts, as it significantly improves energysaving performance by reducing heat loss. high-quality insulation assist on the preserve of the stored hot water by minimizing thermal losses to the surrounding environment, as reported by reddy et al. [39] this section outlines the basic types of insulation materials in which solar thermal water storage tanks, along with the various mounting methods applied to improve temperature retention and reduce standby losses. effective insulation of a solar significantly lowers heat transfer to the surroundings, which is necessary for maintaining stable thermal stratification and ensuring the availability of a multiday hot water buffer.. to low heat losses, a thick layer of high-quality insulation surrounding the tank contributestherefore,it could consume less backup energy for keeping water hot. rao et al. [25] studied various designs of integrated collector storage solar water heater (icsswh) and proposed several ways to reduce heat losses. tthese techniques include a insulated night covers, baffle plate structures, pcms andreverse thermosyphon valves . icsswh systems are considered inexpensive. however, there are some limitations in their commercialization due to high non-collection heat loss and the absence of accurate designs for storage tanks. thus, , various approaches have been proposed to overcome this drawback , such as using insulated covers, double glazing, and selective absorber coatings to reduce the heat loss. additional heat retention methods, such as baffle plates, inner sleeve structures, thermal diodes and reverse thermosyphon designs, can further enhance thermal performance and minimise heat loss. 6.2.1. types of insulation materials various insulation materials are used in solar water storage tanks, each featuring unique properties and suitability for different applications, such as: • foam insulation: rigid foam boards, such as polyurethane or polystyrene, provide excellent thermal resistance and are commonly used due to their high r-value per inch of thickness. these materials are lightweight, easy to install and offer good moisture resistance. • fibreglass insulation: fibreglass batts or blankets are widely used due to their cost-effectiveness and excellent thermal performance. however, proper sealing is required to prevent moisture accumulation and reduce thermal bridging. • vacuum insulation panels (vips): vips offer superior thermal resistance by creating a vacuum within the panel. whilst they provide excellent insulation efficiency, their high cost and handling complexity can be limiting factors. • reflected insulation: reflective foils and coatings can be applied to reduce heat loss by reflecting radiant heat away from the tank. • insulation disks: this material is typically used in combination with other insulations to improve overall performance. aerogels, known for their extremely low thermal conductivity, are highly insulating advanced materials. despite their high cost, these disks are still employed in situations where the cost is insignificant, such as when comparing space requirements with high-performance insulation [40]. 6.2.2. insulation techniques proper insulation of solar water storage tanks requires selecting appropriate materials and applying proper installation techniques, such as the following: • continuous insulation: maintaining insulation along the tank perimeter without gaps or thermal bridges is critical. overlapped and sealed joints in the insulation panels may be crucial to this achievement. • multi-layer insulation: multiple layers of insulating materials can work together, utilising the best properties of each material to maximise thermal performance. a layer of foam board with a reflective foil backing could offer conductive and radiant heat resistance. • sealing and waterproofing: preventing moisture from penetrating the insulation layer is crucial, enabling the insulation layer to perform to its full potential. condensation and moisture, whether from faulty flashing or general wall/roof construction, substantially reduce the effectiveness of insulation materials. however, adopting embedded waterproof barriers as a coating markedly enhances the protection of these materials. • shielded jacketing: encasing the insulated tank in a protective casing or housing can help protect the insulation from physical damage and weather conditions, improving the longevity and ensuring thermal effectiveness [41]. the quality and effectiveness of insulation directly affect the thermal performance of solar water collector storage tank systems. wellnarjes ahmed hussain al-khwarizmi engineering journal, vol. 21, no.3, pp. 7696 (2025) 90 insulated tanks effectively minimise heat losses and sustain high water temperatures for extended periods. this condition optimises the efficiency of the solar thermal system and enhances user comfort and convenience by maintaining a continuous hot water supply. in extremely cold climates, these energy savings multiply due to substantial heat losses through conventional insulation. low usage of such auxiliary heating systems helps conserve energy, resulting in highly sustainable and overall energy-efficient preserved insulating water tanks [42]. considering their notably higher thermal resistance and cost implications, high-performance insulating materials, such as vacuum insulation panels or aerogels, are unlikely to find widespread use. despite the proven durability of spray foam insulation, fibreglass is only second for its performance and affordability. cost, thermal performance, ease of installation and exposure conditions should be considered in the selection of appropriate insulation materials and techniques. overall, insulation is an integral part in the design and operation of iscwsts. the correct selection of materials and insulation methods can efficiently suppress heat loss and preserve thermal stratification, contributing to general energy savings. solar thermal systems will be highly sustainable and feasible as insulation technology advances. fig. 11. schematic illustration of a solar water heater system [47] 6.3. placement and orientation the placement and orientation of iscwsts are crucial considerations that can substantially affect system performance and efficiency. proper placement, which ensures optimal solar exposure and minimal shading, facilitates efficient heat transfer between the solar collectors and the storage tank. singh et al. [43] explored tank placement and orientation as influencing factors on strategies to maximise solar energy harvesting and improve thermal performance. placing the tank in a location with unobstructed access to sunlight for most of the day ensures maximum energy capture. factors such as nearby buildings, trees and topographical features are essential to avoid shading and to maximise solar irradiance on the collectors. 6.3.1. roof vs. ground mounting iscwsts can be either roof-mounted or ground-mounted. both configurations are spaceefficient and help minimise the overall system footprint, making them suitable for residential applications with space constraints. ground mounted systems provide greater flexibility in terms of tank size and orientation, allowing for easier maintenance and access. the choice between roof and ground mounting primarily depends on factors such as available space, structural considerations and aesthetic preferences [44]. narjes ahmed hussain al-khwarizmi engineering journal, vol. 21, no.3, pp. 7695 (2025) 90 6.3.2. orientation madhlopa et al. [11] examined the orientation of the tank relative to the sun, influencing the amount of solar energy captured throughout the day. the tanks are oriented to maximise exposure to sunlight during peak demand hours for optimal performance. in the northern hemisphere, the ideal orientation shall generally be south facing, whilst that in the southern hemisphere is the oppositive. the tilt angle should be adjusted based on latitude to optimise solar incidence angles. conducting a shading analysis is critical to identifying potential obstructions that may cast shadows on the solar collectors or storage tank. tools such as solar path diagrams, shade analysis software and on-site assessments can help periodically determine the extent and timing of shading throughout the year. mitigation measures, such as tree pruning, building modifications or elevated mounting, can minimise shading and maximise solar exposure [45]. in addition to solar exposure, thermal considerations should also influence tank placement and orientation. placing the tank in a location with minimal temperature fluctuations and exposure to extreme conditions should be considered to help maintain thermal stability and reduce heat losses. adequate ventilation and airflow around the tank can also prevent overheating, ensuring efficient heat dissipation [46]. integrating the solar collector water storage tank into the building design can further enhance aesthetic appeal and energy efficiency. architectural features such as awnings, pergolas or integrated solar shading devices can be designed to accommodate solar collectors and storage tanks [48]. this integration not only maximises solar energy capture but also improves the overall visual appeal of the building. adaptive strategies such as adjustable tilt mounts and singleor dual-axis tracking systems can enhance solar collector orientation and increase solar energy capture throughout the day [49]. these systems dynamically adjust the tilt and azimuth angles of the collectors to follows the sun’s path, ensuring optimal solar exposure at all times. although highly complex and costly, these dynamic components offer the potential for high energy yields and improved overall system performance [50]. therefore, a comparative analysis of various placement and orientation strategies reveals that careful consideration of solar exposure, shading and thermal factors is essential for maximising energy efficiency. ground-mounted tanks offer more flexibility in orientation and tilt angles, whilst rooftop mounting optimises space utilisation in areas with limited available space. adaptive strategies provide additional opportunities for finetuning solar energy capture, though they involve higher upfront investment and maintenance costs. overall, the placement and orientation of iscwsts are critical determinants of system performance and efficiency [52]. table 2, summary of (geometry of the tank, thermal stratification, thermal efficiency and economic cost). 7. summary iscwsts are a crucial component in harnessing solar energy for domestic and industrial water heating applications. the geometric design of these tanks notably influences their thermal performance, energy storage efficiency and overall effectiveness. the in-depth analysis of this study of various geometric parameters, such as shape, volume, aspect ratio and insulation, ref. authors nature of the work geometry of the tank thermal stratification thermal efficiency [10] arslan and igci 2015 experimental and numerical cylindrical good, due to their height to diameter ratio good because shape allows for effective heat distribution and collection [17] dolgun et al. 2023 experimental spherical good, due to their uniform geometry very efficient in terms of surface area-to-volume ratio [52] ding et al. 2023 experimental and numerical rectangular poor, the wide base can lead to mixing medium due to greater heat loss at the corners and edges [23] badescu 2008 experimental triangular considered challenge due to their narrow design, which may encourage mixing variable, depends on the tank size narjes ahmed hussain al-khwarizmi engineering journal, vol. 21, no.3, pp. 7696 (2025) 92 provides valuable insights into optimising the design and operation of solar thermal systems. the tank shape, whether cylindrical, spherical, rectangular or triangular, affects key factors such as thermal stratification, heat retention and heat loss characteristics. cylindrical tanks emerge as a favourable option due to their efficient stratification properties and ease of implementation. the balance between thermal demand and heat losses is key wen sizing a tank in terms of volume and capacity. tanks with high aspect ratios promote good thermal stratification but can pose challenges in installation and insulation design. whilst different materials and construction methods affect the performance, effective insulation remains critical for minimising heat loss and maintaining good thermal stability. careful placement and orientation, including factors such as solar exposure, shading analysis or integration within building design, can substantially enhance system efficiency by optimising energy captured and managing module operating temperatures. ground-mounted tanks allow for flexibility in orientation, whereas rooftop mounting can maximise space usage. adaptive strategies, such as tracking systems that adjust solar collectors to follow the sun throughout the day, provide additional chances for optimising solar energy capture but have higher initial installations. overall, the design and implementation of an integrated collector-storage solar water heater ensures proper geometric shaping, insulation and orientation for installation. by optimising these factors, solar thermal systems can improve energy efficiency and serve as an alternative or partial substitute for direct firing systems that use fossil fuels. these systems contribute to sustainability and help reduce carbon oxide footprints. with ongoing research and advancements, solar thermal systems are becoming increasingly powerful energy producers, aligning with the global shift toward a substantially cleaner and more renewable future. future work should conduct additional simulation studies using cfd algorithms in iscwst, aiming to explore the insertion of baffles at the tank inlet to promote thermal stratification, tailored to the geometry of the tank. nomenclature a surface area of the object, [m2] a side length, [m2] b base area, [m2] h height, [m] v volume of the object, [m3] abbreviation cfd computational fluid dynamics icd integrated coupled design ihp insulated hose pipes iscwst integrated solar collector water storage tank p-tank parallel tank swh solar water heater s1-tank interconnect the tanks in one series, with ihp s2-tank interconnect the tanks in two series, with ihp 8. references [1] k. jana; a. ray; m. majoumerd; m. assadi, s. de. polygeneration as a future 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https://doi.org/10.11591/ijeecs.v32.i3.pp1557-1568 https://doi.org/10.11591/ijeecs.v32.i3.pp1557-1568 https://doi.org/10.1016/j.matpr.2020.12.714 https://doi.org/10.1016/j.egypro.2015.02.115 https://doi.org/10.1016/j.solener.2017.03.008 https://doi.org/10.1016/j.solener.2017.03.008 https://doi.org/10.1002/er.3765 https://doi.org/10.1016/j.applthermaleng.2022.119364 https://doi.org/10.1016/j.applthermaleng.2022.119364 ( 2025) 76-96، صفحة 3العدد، 21مجلة الخوارزمي الهندسية المجلد احمد حسيننرجس 96 أثر معايير التصميم في أنظمة خزانات المياه الحرارية: مراجعة 2كريمة إسماعيل عموري ،*1نرجس احمد حسين قسم الهندسة الميكانيكية، كلية الهندسة، جامعة بغداد، بغداد، العراق 1،2 فرنسا ، فاندوفر ليه نانسي f-54500شارع جان المور ul-umr cnrs, 2جامعة لورين ، 2 n.ahmed1703@coeng.uobaghdad.edu.iq*البريد االلكتروني : المستخلص شكال الهندسية يقدم هذا العمل نظرة تاريخية شاملة على خزانات تخزين المياه المستخدمة في جمع الطاقة الشمسية، مع التركيز على استكشاف تأثير ال ،والمستطيلة ، والكروية، خزانات لجمع الطاقة الشمسية. تم استعراض تصاميم الخزانات السطوانية الالمختلفة على الداء الحراري وكفاءة تخزين الطاقة في تي تؤثر على اختيار والمثلثة لتحليل تأثيرها على التدرجات الحرارية، واالحتفاظ بالحرارة، وسعة تخزين الطاقة. كما و ركزت الدراسة على تحديد العوامل ال ونسبة البعاد، مع أخذ ما يعزز تخزين الحرارة في الخزان بعين االعتبار لتقييم الكفاءة الحرارية. أظهرت النتائج أن ، شكل الخزان من حيث الحجم والسعة لنها توفر حجماً مناسباً لمساحة محدودة وسعة عالية ة ؛ والمثلث ةوالمستطيل ةالخزانات ذات التصاميم السطوانية تفوقت على الشكال الخرى، مثل الكروي تقليل نسبة البعاد للخزانات يؤثر بشكل كبير على التدرج من جانب آخر، فإن. من نظيراتها خسائر حرارية أقلكما أنها تمتاز ببفضل نسبة الطول إلى العرض لطاقة الحرارية النقاط الساسية لتصميم أنظمة تسخين لكون زاوية ميل الخزان مع الفق تساوي صفر درجة. تمثل هذه النتائج لتخزين المياه تالحراري عندما للعمل المستقبلي على تقنيات تخزين الطاقة الشمسية ذات درجات الحرارة العالية ودمجها أساسالتعزيز كفاءتها الحرارية. تضع الدراسة ؛ المياه بالطاقة الشمسية ن.حواجز عند مدخل الخزاالمع تقديم اقتراح أمثل لزيادة التقسيم الطبقي الحراري عن طريق إدخال في أنظمة الطاقة المستدامة <4d6963726f736f667420576f7264202d20e6d3e420e6cf20c7cde3cf20e6cf20c7d3c7e3c920312d20203133> this is an open access article under the cc by license : al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 19, no. 1, march, (2023) p. p. 113 a methodology for evaluating and scheduling preventive maintenance for a thermo-electric unit using artificial intelligence wasan mahmood ahmed* ahmed abdulrasool ahmed** osamah fadhil abdulateef* ** *,***department of automated manufacturing engineering/al-khwarizmi college of engineering/university of baghdad, /baghdad/iraq **department of mechanical engineering/ college of engineering/ university of baghdad/ baghdad/ iraq *email: wasanmahmood79@gmail.com *email: dr.ahmed.a.ahmed@coeng.uobaghdad.edu.iq *email: drosamah@kecbu.uobaghdad.edu.iq )2022 october 122022; accepted augest 7 received ( https://doi.org/10.22153/kej.2023.10.001 abstract flow-production systems whose pieces are connected in a row may not have maintenance scheduling procedures fixed because problems occur at different times (electricity plants, cement plants, water desalination plants). contemporary software and artificial intelligence (ai) technologies are used to fulfill the research objectives by developing a predictive maintenance program. the data of the fifth thermal unit of the power station for the electricity of al dora/baghdad are used in this study. three stages of research were conducted. first, missing data without temporal sequences were processed. the data were filled using time series hour after hour and the times were filled as system working hours, making the volume of the data relatively high for 2015-2016-2017. 2018 was utilized as a test year to assess the modeling work and validate the experimental results. in the second step, the artificial neural networks approach employs the python program as an ai, and the affinity ratio of real data using the performance measurement of the mean absolute error (mae) was 0.005. to improve and reduce the value of absolute error, the genetic algorithm uses the python program and the convergence ratio became 0.001. it inferred that the algorithm is efficient in improving results. thus, the genetic algorithm provided better results with fewer errors than the neural network alone. this concludes that the shown network has superior performance over others and the possibility of its long-term predictions for 2030. a sing time series helped detect future cases by reading and inferring system data. the development of appropriate work plans will lower internal and external expenses of the systems and help integrate other capabilities by giving correct data sources of raw materials, costs, etc. to facilitate prediction for maintenance workers, an interface has been created that facilitates users to apply them using the python program represented by entering the times, an hour, a day, a month, a year, to predict the type and place of failure. keywords: maintenance, artificial intelligence (ai), python language . 1. introduction maintenance ensures that equipment and organisms run correctly. it matches technical interventions to the right opportunities, scope, and technical and legal criteria. the maintenance strategy’s goal is to reduce losses by reduction of efficiency and implement perfect operating conditions at the earliest possible delay. the strategy must consider the overall optimized cost [1]. maintenance is categorized by the nature, purpose, and the wasan mahmood ahmed al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 113 (2023) 2 frequency of the job as preventative, predictive, failure-finding, and corrective [2]. maintenance that is scheduled in advance to avoid unexpected breakdowns or failures of a functional system is known as preventative maintenance. equipment failure can be avoided, its functionality can be preserved, and its lifespan can be increased by preventative maintenance. in most cases, the expected lifetime of the equipment will determine how frequently it needs to be maintained [3]. preventive maintenance is a program of planned maintenance procedures to prevent equipment failures. after a certain number of hours, jet engines are lubricated and their lightning arresters replaced. this increases equipment reliability by replacing worn parts before they fail [4,5]. predictive maintenance (pdm) or conditionbased maintenance (cbm) can be performed after collecting and analyzing sufficient physical data, such as temperature, vibration, or oil particle matter. to establish a maintenance plan, data evaluation is performed [4]. infrared, acoustic (partial discharge and airborne ultrasonic), corona detection, vibration analysis, sound level measurements, oil analysis, and others are among the detection methods [5]. failure-finding maintenance comprises of the evaluation of a (quiescent) system portion. this is a fairly frequent occurrence for defensive subsystems. when numerous safety system components fail simultaneously, the consequences might be devastating. inspections uncover issues previously unknown (also called dormant failures). while the element is being inspected, no maintenance is performed unless the component fails the examination, in which case corrective maintenance is conducted [5]. corrective maintenance addresses malfunctioning equipment or systems. this maintenance involves either the replacement or repair of the faulty component. because the failure duration of a component is unclear, corrective maintenance is performed at irregular intervals. after repairs or maintenance, equipment becomes operational. 2. literature review maintenance in production facilities is a very recent topic as the global interest in equipment maintenance leads to lower operating costs in both maintenance and production. it also leads to an overall reduction in production equipment failures and an increase in production potential and efficiency. preventive maintenance (pm) in the production industry is one of the most critical measures to eliminate accidental machinery malfunctions by replacing/repairing damaged machinery or parts. the decision to perform preventive maintenance is not accessible due to the complex and random nature of the industry in which pm is performed. this study emphasizes previous researches that deal with different maintenance techniques. it has been divided into two parts: previous research about its traditional maintenance techniques and research on modern maintenance techniques. many studies specialize in the situation. the following are the most important studies on the proposed system. omur & orhan (2009) [6] dealt with designated preventive maintenance to reduce repair costs and improve device deterioration availability. periodic system checks revealed that deterioration cases occur in the system. naser m. (2010) [7] deals with the use of two different methods, preventive maintenance and the scheduling method. the selected methods calculated the optimal time for supported equipment reliability of optimum time. the result of the maintenance time for both cases is identical but preferred the scheduling method over reliability despite the same effects. moghaddam k. (2010) [8] defined two different maintenance methods, the preventive maintenance and replacement schedule. this thesis resulted in two methods for improving system reliability and availability to reduce maintenance costs and also developed optimization models for pm schedules. the genetic algorithm was used to solve non-linear mixed models. abdulsamat h et al. (2013) [9] referred to reducing tools' scheduled downtime by analyzing and enhancing the checklist preventive downtime by analyzing and enhancing the checklist’s preventive maintenance. it implemented the benefit of having a checklist for elements, smoothed the technicians' work, and reduced the time of stopping the factory. badi i. & shetwan a. (2016) [10] pointed out the significance of indicators for measuring maintenance performance by calculating twelve indicators of maintainability to measure the efficiency of maintenance performance. the final paper results showed a low rate of accessibility to manufacturing actual lines and lower preventive maintenance rates than corrective maintenance. wasan mahmood ahmed al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 113 (2023) 3 adulghafour & abdulwahad i. (2018) [11] created a maintenance plan by applying statistical data to generate a probability-offailure distribution model using the built-in approach to the effect failure pattern critical analysis and fault tree analysis. the researchers concluded that applying the proposed r.c.m. methodology based on preventive maintenance planning will reduce the total value of the maintenance cost of labor signified by a reduction in the time required for repair. dawood l et al. (2018) [12] deals with two inductors' values, the through point and performance indicator values. this paper uses preventive maintenance with m.m.s. in carrying out maintenance actions for all factories. the preventive maintenance with m.m.s. is recycled to choose what greatly affects the improving quality and reliability in the manufacturing works, reducing the product cost by increasing the factory production. ran u et al. (2019) [13] refers to the literature on predictive maintenance with a focus on the purposes and approaches in the industry, as this study showed that any unplanned shutdown of machines or systems would lead to the deterioration of the company's basic business and thus cause great losses. the study showed that traditional maintenance methods suffer from many defects, such as high repair costs, affecting the reputation of companies. therefore, researchers worked on introducing an artificial intelligence method for maintenance, as they formed a model of maintenance models capable of predicting faults before they occur, which reduces the loss of time and money, thus achieving goals for maintenance. mohmmed a et al. (2020) [14] used a dump truck system to discover the components with the lowest reliability and estimate the system failure time. this study developed a preventive maintenance strategy to improve reliability and decrease mountainous costs. the current level of reliability is not convincing. it can be conducted and improved by focusing on some components. the study also suggested that technicians report any errors or outages to avoid any damage. high safety and good operation solved the problem and gave perfect solutions that affected factory systems' failure rate and existence. moghaddam s. (2010) [15] studied to improve the parameter models that reduce the new non-linear function's life. by studying the active life of factory systems, the paper developed a practical method to determine the effect of preventive maintenance on the failure rate. the improved models include a basic trade-off between maintenance replacement costs and failure rate savings. maintenance schedules have been implemented to balance individual operation costs and non-linear optimization models. genetic algorithms have been used to build optimization models, saving designers and analysts time and effort in reaching a final solution. mansour & makhoul (2012) [16] dealt with reaching a high-reliability electrical system that protects the electrical power's permanence. the different method was presented for service continuity in electricity distribution networks through the use of genetic algorithms raised reliable and improved performance have been the data used in the algorithm calculation. the proposed models reduce the cost, and decrease the time of electrical failure and maintenance. rami al-hadithi et al. (2012) [17] suggested the implementation of a preventive maintenance scheduling system based on an intelligent fuzzy logical algorithm. the proposed models proved that time scheduling has many disadvantages that are difficult to include in the information system. therefore, the practical application of theoretical research was developed with optimal variable scheduling time and mounting planning systems to deliver maintenance to customers. the proposed fuzzy replacement system is an advanced and practical solving problem of providing reliable schedules through the enterprise material planning unit and confirmed the success of applying fuzzy logic to solve the scheduling problem. krenek j et al. (2016) [18] dealt with different techniques for maintenance with artificial neural networks in the automotive industry chain. the studies proved that neural networks have strong potential in maintenance tasks. it proposed methods that effect evaluating the risks of faults and early analysis to discover errors. this feature delivers the option of prevention. the new method gives high operative in equipment failure and increases performance results. javanmard h. & koraeizadeh a. (2016) [19] dealt with expecting the activities necessary for preventive maintenance by studying the equipment's optimal costs and reliability. the paper methodology was applied by extracting some data from the equipment and maintenance departments. the lingering data was acquired through the application of a genetic algorithm that predicted downtime, costs, and reliability in a predetermined period. the proposed methods applied the extracted feature to all manufactured and non-manufactured equipment. gregor m et wasan mahmood ahmed al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 113 (2023) 4 al. (2016) [20] dealt with explaining a new generation of industrial automation, intelligent production, and development towards the industry. this system statement in organizations takes the role of increasing the performance system about the costs experienced. this paper discusses integrating a reconfigurable maintenance system into the system's production. it deals with adversative production conditions and confirms reliability for production configurations. alhamad k et al. (2016) [21] dealt with reliability, a key decision tool that improves maintenance scheduling for cogeneration plants. the paper's 4 points are better than 2 points for each electricity and water concentration. the numerical analysis used for genetic algorithms may improve the diagnostic mathematic solutions. the works' goal can be expanded to include the maintenance and production costs of optimal units. the paper method was used to create all possible schedules with the optimal cost solution. montiel a et al. (2017) [22] progressed the preventive maintenance procedures used by the medium-voltage electricity distribution companies, especially on time and cost. the improvement is based on the real data of the station implemented for the genetic algorithm to have the optimal solution. the proposed methods were theoretically done by a simulation for a whole year of station results. the model can use this approach to significantly improve the process of performing preventive maintenance. vannucci m. et al. (2018) [23] proposed a new type of genetic algorithm for industrial optimization. this method used a genetic algorithm with a fuzzy inference system approach that controls the search strategies of the algorithm. this method is called the far method. this method prevents the optimization from attaining the minimum level instead of the overall level; therefore, relies on controlling genetic algorithm recombination rates by taking out features that define the stage of development. the proposed methods enhanced the performance of industrial maintenance. it has the ability to troubleshoot faults with high efficiency, avoid lower limits, and reduce the time required for improvement. bampoula x. et al. (2021) [24] dealt with an approach to qualifying the change from preventive maintenance with a deep learning algorithm for planning maintenance events to the equipment's actual operating condition. in this paper study, real data was calculated to form training and testing of the prototype model executed in the python language. the proposed method reduced the cost of maintenance and redundant downtime. 3. proposed system the proposed system has different stages and steps; the first stage includes describing the system under study and its subsystems, the dataset collection, categorization, and creation of the enhancement data that suits the required research. the second stage contains the application of the proposed model by designing the ann and then integrating the genetic algorithm with the ann. the third and final stage is predicting the results. figure 1 shows the three stages and steps necessary to implement the proposed methodology. wasan mahmood ahmed al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 113 (2023) 5 fig. 1. stages and steps proposed methodology. 3.1 first stage system description: al-doura power station is a steam-powered electric power station located in baghdad near the tigris river. it consists of six units, the first and second units are out of service because of the war conditions, and the branches 3,4,5, and 6 are currently working and generate electricity for the capital baghdad with a production capacity estimated at (400 mw) per unit with all units connected. system description data gathering form unit 5 preprocessing data subsystem classification failure date indexing "time series" turbin genrator condenser generato r electrical control mechanical fill missing time series create new data with filling missing samples label encoding reframe data phase 1 phase 2 neural network regression using ga design the ann apply ga use ga weights for model prediction phase 3 wasan mahmood ahmed al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 113 (2023) 6 figure 2 shows the subsystems (the main parts) of the generating units of the station. each unit consists of four main parts linked together respectively. the failure in any part leads to the stopping of the parts (boiler, turbine, generator, and condenser). unit 5 was chosen as a case study of race methodology; the data were collected over a span of four years (2015-2018). fig. 2. parts of unit. while filling the missing dataset, the dataset collected from previous studies suffers from random time jumps and missing values. there is also a significant variation in the standard periods. this fluctuation leads to an effect on practical training, which means the results will be completely inaccurate. to solve this issue, process the dataset and convert it to a time series data set. then, the new dataset treats periodically within the standard period difference, coding failure, and reasons. unit 5 has four parts (boiler, turbine, generator, and condenser), as shown in figure 2, this kind of failure is a system in one column labeled btgc. write a python program to code the type of failure depending on the first letter of failure type as an abbreviation for the initials of the components, for example, ‘b’ for boiler, ‘t’ for turbine, ‘g’ for generator, and ‘c’ for condenser. table 1 includes the encoding failure and failure reason specifically. table 1, coding failure and reason code value btgc failure type 0 low vacuum mechanical 1 check vibration mechanical 2 electrical and hydraulic suddenly open control 3 shutdown mechanical 4 signal under voltage electrical 6 high temp in room exciter electrical 7 control room mechanical 8 reply valve 5 nm28 safety mechanical 9 the trip by signal drum level high mechanical 10 over current electrical 11 push button fire protection mechanical 12 the trip by signal i.p.s logic control 13 a trip by signal loss of both (f.d.f g.r.f ) mechanical 14 high pressure mechanical 15 vacuum low mechanical 16 steam leakage at the control valve mechanical 17 high vibration in all bearing mechanical 3.2 second stage an artificial neural network (ann) was utilized, the data that was enhanced is going to be an input of the ann network, and then the output is the prediction of failure type and time delay. most importantly, the model can predict until the year 2030. the design of a fully connected ann was created with 15 neurons of 2 hidden layers and two outputs; figure 3 shows wasan mahmood ahmed al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 113 (2023) 7 the structure of the ann. where ‘w’ is the weight to be trained and ‘b’ is the bias used to adjust the output along the weighted sum. the activation function is the sigmoid function used to scale the work. fig. 3. ann network structural. training and testing are neural network processing phases. 80% of the data is used for training and 20% is used for testing. training involves adjusting weights and biases to produce accurate results. supervised training is most general type. backpropagation trains and modifies the network to reduce output errors. adjusting initial random weights and biases begins network training. forward-propagation of intermediate results produces the output vector. the difference between the target and network outputs equals error. the backpropagating network error modifies the weights and biases to reduce cycle prediction error. during testing, the network's structure doesn't change. using an ann, the ga (genetic algorithms) generates several potential solutions to the issue and then refines them throughout several generations. every answer contains all of the parameters that could contribute to improving the findings. when applied to an ann, weights in each layer contribute to the excellent accuracy that can be achieved. because of this, a single solution in the ga will include all of the weights. fig. 4. genetic algorithm to adjust the weight. 3.3 third stage the predictions validation of the ann algorithm was in 2018. the ann algorithm was validated by comparing the predicted results of the failure type and its reasons of occurrence with the actual data (2018). figure 5 shows a comparison of the actual data with the predicted wasan mahmood ahmed al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 113 (2023) 8 data by using an ann, which indicates the actual values of no failure are equal to 7605 hours and the predicted value was 7700 hours. the mechanical failure can also be seen to be equal to 1033 in reality and 1008 from the prediction, then the number of electrical failure hours in reality and prediction is 122 and 50, respectively. fig. 5.comparing results using ann based on failure type in 2018. validation of predictions using an ann and ga in the year 2018 was achieved after optimizing the weights of the ann by using the genetic algorithm. figure 6 shows a comparison of the real data with the predicted data by using an ann with a ga, which indicates the real values of no failure are equal to 7605 hours and the prediction’s values were 7650 hours. the mechanical failure can also be seen to be equal to 1033 in reality and 1018 in the prediction, then the number of electrical failure hours in reality and in the prediction was 122 and 90, respectively. fig. 6. comparing results using ann with ga based on failure type in 2018. the comparison between the percentages of hours for each type of failure is shown in figure 7. the predicted rate of the number of hours in no failure using ann with ga is more up to date than the predictions using the ann alone. 0 1000 2000 3000 4000 5000 6000 7000 8000 no failure electrical mechanical 7605 122 1033 7700 50 1008 n u m b e r o f h o u r s actual predict 0 1000 2000 3000 4000 5000 6000 7000 8000 no failure electrical mechanical 7605 122 1033 7650 90 1018 n u m b e r o f h o u r s actual predict wasan mahmood ahmed al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 113 (2023) 9 fig. 7. comparing results between actual and after genetic and before genetic. 4. results and discussion to show the results clearly, a comparison between the two proposed approaches was carried out in the predictive years 2019 and 2020. to verify and compare the two approaches, compare the prediction of failures for 2019 using ann alone and an ann with a ga, as shown in figure 8. it's clear from this figure that the predictions using an ann with a ga are better than using an ann alone. note that the percentage of continuity of the system work using an ann alone is 23%. in comparison, it increased to 28.6% using an ann with a ga, while for mechanical failures; the percentage of predictions using ann alone is 59.4%. it decreased when using ann with ga to 56.4%. the rate of electrical failures in an ann alone is 17.6%, while it decreased by using ann with ga to 15%. fig. 8. the general percentage of failure types using ann and ann with ga in 2019. 0.00% 10.00% 20.00% 30.00% 40.00% 50.00% 60.00% 70.00% 80.00% 90.00% nofailure electrical mechanical 86.80% 1.40% 11.80% 87.35% 1.03% 11.62% 87.92% 0.57% 11.51% p e r c e n t a g e o f h o u r s actual ann with ga ann 0.0% 10.0% 20.0% 30.0% 40.0% 50.0% 60.0% nofailure electrical mechanical 23.0% 17.6% 59.4% 28.60% 15% 56.40% p e r c e n t a g e o f h o u r s ann2019 annwith ga 2019 wasan mahmood ahmed al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 113 (2023) 10 to verify and compare the two approaches, compare the predictive failures for 2020 using ann alone and an ann with a ga, as shown in figure 9. it's clear from this figure that the predictions using an ann with a ga are better than using ann alone, note that the percentage of continuity of the system work using an ann with a ga is 30%, while it decreased to 27% when using an ann alone. for mechanical failure, the percentage of predictions when using an ann with a ga is 41%, while it increased when using an ann alone to 43%. the rate of electrical failure in an ann with a ga is 27.5%, while it increased when using ann alone to30%. it was concluded by comparing the predictions for 2020 that the use of an ann with a ga is the best option for improving the accuracy of predictions, as well as for the years 2018 and 2019, which indicates that the use of an ann with a ga represents the best model for obtaining more accurate predictions. fig. 9. percentage of failure type in general by using ann and ann with ga in 2020. a failure prediction program that can predict from 2018 until 2030 was designed; the user can enter the application system after completing the registration and enter the data including year, month, day, and hours to predict the failure time and type. solutions for long-range time prediction can estimate the failure time and type util 2030 as explained in figure 10. 0.0% 5.0% 10.0% 15.0% 20.0% 25.0% 30.0% 35.0% 40.0% 45.0% nofailure electrical mechanical 27.0% 30.0% 43.0% 30% 27.10% 41.00% p e r c e n t a g e o f h o u r s ann2020 annwith ga 2020 wasan mahmood ahmed al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 113 (2023) 11 fig. 10. predicate of 2030. 5. conclusions anns can be used extensively in prediction and modeling, especially in solving problems with a non-linear pattern that change with time, which causes difficulty in modeling the relationship between input and output. a ga was used to determine and select the initial weights and basis for the backpropagation neural network to avoid convergence in the optimal solutions. the results showed that the developed network performed much better than others. time series help find future states through reading and inference from the current results available to monitor the system's condition at a future time. the possibility and accuracy of the prediction depends on the amount of information available about the system's working mechanism. the methodology proposed in this thesis can be applied to all systems operating in maintenance systems, and it gives an excellent indication to the different departments on developing appropriate action plans and what is expected. thus, it will reduce the internal and external costs of such systems. the ability of the applied program (python) can be used to integrate other capabilities through the availability of accurate data as sources for raw materials, costs, and others. the future works for this research are: building a new fuzzy neural network model in determining costs and demand time for the type and size of replacement parts and using another neural network of different structures such as jordan and another web to deal with the data series used and compare the results, forecasting faults for intermittent production systems using artificial intelligence methods, and finally, building an integrative program by predicting subsystem failures and comparing it with the main system program. 6. references [1] n. m. durakbasa, g. bas, l. kräuter, and g. poszvek, “the assessment of industrial manufacturing systems towards advanced operations by means of the integrated modeling approach,” vis. 2020 innov. dev. sustain. econ. growth proc. 21st int. bus. inf. manag. assoc. conf. ibima 2013, vol. 2, no. january, pp. 1418–1426, 2013. 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[22] m. vannucci, v. colla, s. dettori, and v. iannino, “fuzzy adaptive genetic algorithm for improving the solution of industrial optimization problems,” j. intell. syst., vol. 29, no. 1, pp. 409–422, 2020, doi: 10.1515/jisys-2016-0343. [23] x. bampoula, g. siaterlis, n. nikolakis, and k. alexopoulos, “a deep learning model for predictive maintenance in cyber-physical production systems using lstm autoencoders,” sensors (switzerland), vol. 21, no. 3, pp. 1–14, 2021, doi: 10.3390/s21030972. [24] t. miller, “explanation in artificial intelligence: insights from the social sciences,” artif. intell., vol. 267, pp. 1–38, 2019, doi: 10.1016/j.artint.2018.07.007. wasan mahmood ahmed al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 113 (2023) 13 منهجية لتقييم وجدولة الصيانة الوقائية لوحدة حرارية كهربائية باستخدام الذكاء االصطناعي اللطيف*** الرسول احمد ** اسامه فاضل عبد احمد عبد وسن محمود احمد* قسم هندسة لتصنيع المؤتمت/ كلية الهندسة الخوارزمي/ جامعة بغداد****،* قسم الهندسة الميكانيكية/ كلية الهندسة/ جامعة بغداد ** wasanmahmood79@gmail.com*البريد االلكتروني: dr.ahmed.a.ahmed@coeng.uobaghdad.edu.iq**البريد االلكتروني: drosamah@kecbu.uobaghdad.edu.iq**البريد االلكتروني: الخالصة (محطات أوقات مختلفة في تحدث المشاكل ألن التوالي على قطعها توصيل يتم التي واإلنتاج التدفق الصيانة ألنظمة جدولة إجراء يتم ال قد والذكاء األسمنت، مصانع الكهرباء، المعاصرة والبرمجيات التنبؤية الصيانة برنامج تطوير من خالل البحث أهداف لتحقيق المياه). تحلية محطات المفقودة التي تمت معالجة البيانات أوالً،أجريت ثالث مراحل في البحث. الحرارية، لمحطة الدورة االصطناعي وتم العمل ع بيانات الوحدة الخامسة البيانات باستخدام السالسل الزمنية ساعة بعد ساعة وأوقات الملء كساعات عمل البيانات مما يجعل حج النظام،كانت بدون تسلسل زمني. تم ملء م للفترة نسبًيا استخدام ٢٠١٧٢٠١٦٢٠١٥مرتفعًا وتم الخطوة ٢٠١٨، في التجريبية. النتائج من صحة والتحقق النمذجة لتقييم عمل اختبار كسنة خدام قياس األداء (متوسط ونسبة التقارب إلى البيانات الحقيقية باست اصطناعي،استخدم نهج الشبكات العصبية االصطناعية برنامج بيثون كذكاء الثانية، لتحسين أوزان الشبكة المطلق، وتقليل نسبة الخطأ ولتحسين .mae (0.005) الخطأ المطلق) وأصبحت العصبية،تم استخدام الخوارزمية التطورية التقارب تقدم الخوارزميات الجينية نتائج أفضل مع أخطاء أقل من النتائج وبذلكيستدل من ذلك كفاءة الخوارزمية في تحسين .mae (0.001) نسبة ، وأن استخدام ٢٠٣٠طويل األمد لسنة التنبؤ ع وإمكانيتها الشبكات العصبية وحدها. يخلص هذا إلى أن الشبكة المبنية تتمتع بأداء متفوق عن اآلخرين ة ساعد في اكتشاف الحاالت المستقبلية من خالل قراءة بيانات النظام واستنتاجها. وسيؤدي وضع خطط عمل مناسبة إلى خفض النفقات السالسل الزمني وغي والتكاليف الخام للمواد كمصادر الصحيحة البيانات إعطاء خالل من األخرى القدرات تكامل في والمساعدة لألنظمة والخارجية .رهاالداخلية –شهر –يوم للعاملين ع الصيانة تم انشاء واجهات تسهل ع المستخدمين تطبيقها باستخدام برنامج بايثون ممثلة بإدخال االزمان ساعة التنبؤولتسهيل بنوع ومكان الفشل. للتنبؤسنة this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 20, no. 1, march, (2024), p p. 4250 influence of zirconia and polymerized microfiller on some properties of polymethyl methacrylate denture base duaa subhi rasan* firas abdulameer farhan** *department of prosthodontics/ college of dentistry/ university of baghdad/ iraq **department of prosthodontics / college of dentistry/ university of baghdad/ bab al-muadham campus of the university of baghdad/ iraq corresponding author: *email: drduaasubhi@gmail.com **email: firas.farhan@codental.uobaghdad.edu.iq (received 7 may 2023; accepted 30 august 2023; published 1 march 2024) https://doi.org/10.22153/kej.2024.08.001 abstract polymethyl methacrylate (pmma) is the material of choice for denture bases due to its ease of production and repairability, biocompatibility, and exceptional aesthetic appeal. however, the shortcomings of polymer materials, like inadequate mechanical and physical properties. the goal of recent study was to assess transverse strength and wettability of pmma when mixing with zirconia and polymerized pmma particles [zp] as fillers with a different percentage. sixty pmma samples were split into three groups based on the percentage by weight of zp filler added to each: group c: control group, 20 samples without zp filler (0%wt.zp); group a: 20 samples with 2%wt. zp; and group b: 20 samples with 4%wt. zp. flexural strength and wettability tests were used to evaluate all samples. zp powder had prepared and blended by weight with pmma powder in two distinct amounts, 2% and 4% [1.2µm and 30%zro, 0.69µm and 70% ppmma had selected according to pilot study]. to polymerize the specimens, the usual heat-curing procedure was used using a water bath, for both transvers flexural strength and wettability tests. one-way analysis of variance (anova) test was used to analyse data, and the results were considered statistically significant when the p-value was less than 0.05. the results showed that adding 2% zp powder to pmma significantly increased transverse strength, whereas adding 4% zp powder significantly decreased transverse strength. the wettability improved dramatically between the 2% and 4% concentrations. the mixture of zirconia and polymerized pmma particles utilized as dental filler at 2% and 4% wt increased wettability with increasing concentration, while increasing transverse strength ranged from increased to decreased. keywords: polymethylmethacrylate (pmma), zirconia, polymerized pmma, transvers flexural strength, wettability. 1. introduction the development of acrylic resin in 1936 was a significant step forward that has influenced contemporary dental practice. the majority of traditional removable dentures used to restore edentulous individuals are made of acrylic resin (1). despite the extensive usage of polymethyl methacrylate (pmma) in prosthetic dentistry, denture breakage remains a regular clinical occurrence in prosthodontic services and still an unsolved problem (2). many research have been conducted with the purpose of increasing the characteristics of pmma by including fillers into the composition. to enhance its physical and mechanical properties, pmma is often mixed with fillers and particles (3,4,5). the heat-cure denture base resin or pmma materials now available on the market are distributed as a two-part powder and liquid solution. monomeric methyl methacrylate is the primary ingredient in the liquid component, mailto:firas.farhan@codental.uobaghdad.edu.iq https://doi.org/10.22153/kej.2024.08.001 duaa subhi rasan al-khwarizmi engineering journal, vol. 20, no. 1, p.p. 4250 (2024) 43 while prepolymerized poly (methyl methacrylate) makes up the bulk of the powder (6). the addition of metal powder fillers silver, copper, and aluminum particles to pmma improved its strength (7). zirconia's potential for incorporation into a wide range of dental materials has been investigated, and it has been discovered to be biocompatible and to increase mechanical qualities (8). researchers have shown that zirconia is not only biocompatible, but also aesthetically superior to metal fillers. zirconium powder, as studied by n m ayad et al., greatly boosts the transverse strength of high impact resin, which was shown to be significantly strengthened when reinforced with 5% and 15% zro2(9). the addition of polymerized pmma powder to heat-cure acrylic resin changes the chemical and physical properties (10). the impact strength and hardness of heat polymerized pmma resin were improved after varying amounts of mixture of polymerized pmma and zirconia fillers were added (11). the results are usually better when using a combination of reinforcement types rather than just one. each additional reinforcement is thought to improve a different material quality (12). the current research aimed to investigate the transversal strength and wettability after incorporating a mixture polymerized pmma and zirconia particles into heat-cure pmma resin. 2. experimental study 2.1 materials in current study, the mechanical and physical qualities of polymethylmethacrylate (pmma), like transversal strength and wettability, were tested, before and after collaborating with mixture of zirconia and polymerized (pmma). 2.1.1 polymethylmethacrylate (pmma) commonly known as "acrylic resin" or "methacrylic resin," the scientific name is "polymethyl methacrylate" (pmma). the chemical formula for this material is (c5h8o2)n,. most full dentures nowadays are made from acrylic resin that is heat-cured. these are available in the form of powder poly (methyl methacrylate) and liquid methyl methacrylate. the monomer and polymer mix to make a workable dough that has several applications. 2.1.2 zirconia (zro2) zirconia, which is also called zirconium dioxide (zro2), is one of the most common ceramic materials used today. mechanical engineering has made use of them. they are well-suited for numerous components, such as engine parts, cutting tools, and dentures, due to their very high strength, hardness, fracture toughness, and wear resistance. adding zirconia (zro2) fillers to pmma has been shown to greatly improve the material's flexural strength, impact strength, fracture toughness, and hardness. 2.1.3 polymerized pmma it is an additive substance used to test the physical and chemical characteristics of heat-cured acrylic resin; another name for it is recycled polymethylmethacrylate. chemical and physical properties of thermal acrylic resins are altered when polymerized polymethylmethacrylate is added, one such alteration is decrease the release of residual monomer. 2.1.4 preparation the mixture of polymerized pmma and zirconia heat cure pmma resin balls (spofa dental, markova, czech republic) were made according to the manufacturer's instructions. the mechanical grinding-milling equipment (silver crest, zhejiang, china) ground the resulting pmma balls and sieved using the sieving machine (fritsch, gmbh, germany) to create a powder with an average particle size of 0.69µm. to create a mixture of polymerized pmma and zirconia powder (zro2) filler, 70% (w/w) polymerized pmma powder (0.70µm) was mixed with 30% (w/w) (zro2) (1.2µm) (fixanal, sigma aldrich, germany). 2.2 fabrication of samples totaling 60 were split into two groups of 30 (one for each test) and then further separated into three groups of 10 (one for each % of zp filler) for analysis. the subdivided group tested for transvers strength and wettability. the recommended pmma/zp research composite material was constructed using the duaa subhi rasan al-khwarizmi engineering journal, vol. 20, no. 1, p.p. 4250 (2024) 44 following measurements (to create a pmma/ zp composite, we used electronic balance to add zp at 2% wt. to a pmma resin basis at 98% wt., and at 4% wt. to a pmma resin base at 96% wt.) the selection of the ratio of the addition of zp to pmma resin was designated according to the pilot study. to ensure that the zp would be conventional compression method. following the manufacturer's guidelines, the pmma powder and liquid were mixed together (spofa dental, at 74 degrees celsius, followed by 1/2 hour at 100 degrees celsius). after taking the flask out of the water bath, it was allowed to cool at room czech republic). following the manufacturer's instructions, a short-cycle heatpolymerization processing procedure was carried out (1.5 hours evenly distributed throughout the acrylic resin powder and that the color would be constant, the mixes were blended at 400 rpm for 30 minutes. plastic sheets were prepared for transvers strength and wettability checks. by use of a water-bath curing apparatus, pmma and pmma/zp composites were cured in the conventional compression method. following the manufacturer's guidelines, the pmma powder and liquid were mixed together (spofa dental, czech republic). following the manufacturer's instructions, a short-cycle heatpolymerization processing procedure was carried out (1.5 hours at 74 degrees celsius, followed by 1/2 hour at 100 degrees celsius). after taking the flask out of the water bath, it was allowed to cool at room temperature. after being completed and polished using a standardized procedue, all of the pmma samples were kept in distilled water for 2 days before to testing. 2.2.1 transverse strength test the specimens' (30 specimens) dimensions (65mm length, 10mm width, and 2.5mm thickness) employed in this study are depicted in fig. 1 fig. 1. transverse strength testing specimen dimensions. the test was conducted using an instron universal testing equipment (wdw-20, laryee technology co., ltd., china) , and the specimens were placed on bending fixtures made of two parallel (50 mm) supports, and the force was applied using a rod centered between the supports creating deflections till a fracture occurred. the transverse strength was calculated using the equation below: t = 3pl/ 2pd2 (ada specification no.12, 1999) t= transverse strength (n/ mm2) p= maximum force that exerted on samples (n) l= distance between the supports (mm) b= the samples width (mm) d= depth of the samples (mm) 2.2.2 wettability test specimens (30) with dimensions of 20mm in length, 15mm in width, and 2mm in thickness were created (ramanna, 2018), as seen in fig. 2. fig. 2. dimensions of wettability specimen test. as contamination of the investigated surfaces is likely to introduce an error, the test specimens in this investigation were manufactured on a regular basis. measurements in this study were taken using a contact angle goniometer (nanoscience instruments, usa), a direct optical method distinguished by its simplicity. the wettability of samples was determined by applying a single drop of distilled water at room temperature. 3. statistical analysis data description, analysis and presentation were performed using statistical package for social science (spss version -22, chicago, illionis, duaa subhi rasan al-khwarizmi engineering journal, vol. 20, no. 1, p.p. 4250 (2024) 45 usa), minimum, maximum, mean, standard deviation (sd) and standard error (se), simple chart bar and one way analysis of variance (anova) test. 4. results and discussion figures (3) and (4) show the results of microscopic tests performed on control and experimental specimens zp 2% wt. using a field emission scanning electron microscope (fe-sem) at 1.00kx magnification. as can be seen in fig. 4, the zp fillers are evenly dispersed throughout the polymer matrix. fig. 3. fe-sem of the fractured surface of control sample at magnification 1.00kx fig. 4. fe-sem of the fractured surface of reinforced specimen with 2%zp at magnification 1.00kx descriptive statistical analyses of transverse strength for all groups evaluated were available, the highest mean value of transverse strength is related to a group (106.30 nmm2), while the lowest mean value was related to b group (86.74 nmm2) followed by group (97.16 nmm2) as shown in table1. table 1, descriptive statistics of transverse strength (n\mm2) among groups. groups n mean ±sd ±se minimum maximum c 10 97.156 3.024 0.956 93.000 103.330 a 10 106.303 5.600 1.771 99.650 118.730 b 10 86.741 1.633 0.516 84.900 90.600 n: number; sd: standard deviation; se: standard error. the mean values of transverse strength results represent in fig. 3. the one-way anova test for comparing mean values of control and experimental groups reveals a significant (p<0.05) difference between groups, as shown in table 2. duaa subhi rasan al-khwarizmi engineering journal, vol. 20, no. 1, p.p. 4250 (2024) 46 fig. 3. bar chart of mean values of transverse strength test among studied groups. table 2, one-way anova test of transverse strength (n\mm2) among groups. sum of squares df mean square f p value between groups 1916.03 2 958.02 66.58 0.000 within groups 388.51 27 14.39 total 2304.55 29 a material's transverse is a measure of its stiffness and resistance to fracture. because of its potential significance to a denture base's loading properties, transverse strength tests were conducted (13). the means value of transverse strength and the one-way anova test in tables (1, 2) and figure (1), showed that adding zp (group a and group b) to pmma was significantly increased and decreased respectively comparison with the control pmma, this increase in transverse strength may be related back to the interruption in the crack propagation that occurred during the interstitial filling of the acrylic resin matrix with zp (14). when 4% zp was added, the transverse strength decreased as compared to 2% zp, an increase in filler usage may be responsible for this drop. it's possible that after a saturation threshold is achieved, the effect of greater filler content on strength disappears, no additional filler particles may be incorporated into the resin. when filler particles are added to a matrix that has already attained saturation, the resin matrix continuity is broken, and the strength of the reinforced specimens decreases (15). previous research indicated that adding 0.125% and 0.25% weight silicon carbide nanoparticles to acrylic denture base material had no significant effect on the material's transverse strength, impact strength, and surface roughness (16). transverse strength values were found to be highest for (pmma) reinforced with glass fibres, then for (pmma) reinforced with butadiene styrene, and lowest for conventional denture base resins (jaikumar et al., 2015). glass fibers have a substantial impact on individuals who have a thick occlusal load or when the denture base resin fractures (17). descriptive data for the wettability test were shown in table 3. for both the control and experimental groups, ), the highest mean value of contact angles was related to c group (71.32°) and followed by a group (67.61°), while the lowest mean value was established with the b group (62.69°). fig. 4. comparison of mean wettability (contact angle) test scores between groups duaa subhi rasan al-khwarizmi engineering journal, vol. 20, no. 1, p.p. 4250 (2024) 47 table 3, descriptive statistics of wettability(contact angle°) among groups n: number; sd: standard deviation; se: standard error. as can be seen in table 4, there is a statistically significant (p<0.05) difference between the control and experimental groups when comparing their mean values table 4, one-way anova of wettability test (°) among groups. wettability is the amount of wetness that occurs when solid and liquid phases contact (18). its determine how moist or dry something is (whether it's hydrophilic or hydrophobic), by testing its surface wettability with a liquid (19). contact angle is a crucial factor in determining how wettable bases for dentures are. each substance has its own characteristic angle, which is related to the surface energy of solids and the surface tensions of liquids. (20). according to the result in the current study, table (3 and 4), figure (4) the wettability value was increased with increase zp particles integrated material (decreased contact angle). this might be due to the zirconia particles which, if utilized, would decrease the absorbent polymer's bulk because they are insoluble in water (21). possible explanations for the second element include the mixture of zirconia and polymerized pmma particles that increase the surface roughness of modified specimens (11), this findings can also be explained by the direct relationship between wettability and surface roughness, so the addition of zp increase surface roughness, it increase wettability (decrease contact angle) (22,23). previous research indicated that adding 1wt.% and 1.5wt.% of silanized microcrystalline cellulose powder had a highly significant increase in contact angle values of wettability test (decrease wettability) between control group and both experimental groups (24) ismaeel ij et al. (2015) showed that the incorporation of silanated polypropylene fibers resulted in a considerable increase in wettability (25). 5. conclusion the addition of 2% zp fillers to heatpolymerized pmma resin resulted in improved transverse strength, while wettability was enhanced at different percentages of zp fillers. these findings imply that altering heat-polymerized pmma resins with suitable fillers can improve the fracture resistance and survival rate of denture bases. however, it is critical to examine the correct concentration of fillers in order to produce the necessary mechanical characteristics and wettability for certain therapeutic applications. more research and long-term experimental studies are needed to confirm these findings and evaluate the effectiveness of these modified pmma resins in practical dental applications. groups n mean ±sd ±se mini. maxi. c 10 71.324 2.866 0.906 66.500 75.010 a 10 67.610 2.430 0.768 63.300 70.500 b 10 62.694 3.942 1.246 57.620 67.820 sum of squares df mean square f p value between groups 374.79 2 187.396 18.96 0.000007 within groups 266.89 27 9.885 total 641.68 29 duaa subhi rasan al-khwarizmi engineering journal, vol. 20, no. 1, p.p. 4250 (2024) 48 references [1] paranhos, h.f., peracini, a., pisani, m.x., oliveira, v.c., souza, r.f. and silva-lovato, c.h. 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[18] montajar sarkar, ... armh rashid, in reference module in materials science and materials engineering, 2020 duaa subhi rasan al-khwarizmi engineering journal, vol. 20, no. 1, p.p. 4250 (2024) 49 [19] powers, j., sakaguchi, r. and ferracane, j. (2019). craig’s restorative dental material. 14th ed. st. louis, missouri: elsevier, 116, 166, 165, 43, 64, 48, 142, 58, 60. [20] jin, n.y., lee, h.r., lee, h. and pae, a. (2009). wettability of denture relining materials under water storage over time. the journal of advanced prosthodontics, 1(1), 1–5. [21] ferracane jl. hygroscopic and hydrolytic effects in dental polymer networks. dent mater 2006;22: 211– 22. [22] zelazinski, t., sloma, j., skudlarski, j. and ekielski, a. (2020). the rape pomace and microcrystalline cellulose composites made by press processing. sustainability, 12(4), 116. [23] kubiak, k., wilson, m., mathia, t., and carval, p. (2011). wettability versus roughness of engineering surfaces. wear, 271(4), 523-528 [24] raghdaa k.,n.m. zaidan(2022). "effect of silanized microcrystalline cellulose incorporation on physico-mechanical properties and denture base adaptation of heat cured acrylic material. a master thesis, department of prosthodontics, university of baghdad. [25] intisar j. ismaeel, hasanain k.a. alalwan, mustafa m.j.,(2015).the effect of the addition of silanated poly propylene fiber to polymethylmethacrylate denture base material on some of its mechanical properties. j bagh coll dentistry; 27(1):4047. (2024) 42-50، صفحة 1، العدد20المجلد جلة الخوارزمي الهندسيةم دعاء صبحي رسن 50 نيا والحشو الدقيق المبلمر على بعض خصائص قاعدة طقم األسنان بولي ميثيل تأثير الزركو ميثاكريالت فرحان** فراس عبد األمير *دعاء صبحي رسن العراق /جامعة بغداد /كلية طب األسنان /قسم االستعاضة السنية* العراق /جامعة بغداد /كلية طب األسنان ** drduaasubhi@gmail.com :البريد االلكتروني* firas.farhan@codental.uobaghdad.edu.iq :البريد االلكتروني** الخالصة كمادة أساسية ألطقم األسنان من سهولة المعالجة واإلصالح والتوافق الحيوي والمظهر (pmma) ميثاكريالتيأتي االستخدام العالمي لبولي ميثيل مثل الخواص الميكانيكية والفيزيائية غير كافية. كان الغرض من هذه الدراسة هو تقييم القوة البوليمر،فإن أوجه القصور في مواد ذلك،الجمالي الممتاز. ومع pmmaكمواد مالئة بنسبة مختلفة. تم تقسيم ستين عينة [zp] المبلمرة pmma واالختالط مع جزيئات الزركونيا بعد pmma المستعرضة وقابلية البلل ٪ zp (0عينة بدون حشو 20 الضابطة،: المجموعة cالمضاف إلى كل منها: المجموعة zpإلى ثالث مجموعات بناء على النسبة المئوية بالوزن لحشو العينات. ٪. تم استخدام اختبارات قوة االنحناء وقابلية البلل لتقييم جميع 4عينة بوزن 20؛ والمجموعة ب: zp٪ 2عينة بوزن 20بالوزن. (؛ المجموعة أ: -p٪ 70ميكرومتر و 0.69و zro٪ 30ميكرومتر و 1.2]٪ 4٪ و 2بالوزن بنسبتين مختلفتين pmma وخلطه مع مسحوق zp تحضير مسحوق تم pmma . لكل من اختبارات قوة المرونة وقابلية البلل. تم تحليل البيانات مائي،باستخدام حمام ةتم استخدام إجراء المعالجة الحرارية المعتاد العينات،لبلمرة p) معنوية تبلغ p مع قيمة (الالحقة dunnett's t3 و tukey's hsd مع اختبارات anova) من الدراسة باستخدام تحليل التباين أحادي االتجاه ٪. بينما حدث انخفاض كبير بنسبة 2بنسبة pmma إلى zp وكانت النتائج زيادة معنوية في قوة المرونة المستعرضة لوحظت مع إضافة مسحوق (0.05> الوزن. ٪ ب 4٪ و 2المبلمرة المستخدمة كحشو األسنان في pmma ٪. مزيج من زركونيا وجزيئات4٪ و 2٪. لوحظت زيادة كبيرة في قابلية البلل بنسبة 4 .في حين عززت قابلية البلل مع زيادة التركيز التوالي،تعزيز وتقليل القوة المستعرضة على mailto:firas.farhan@codental.uobaghdad.edu.iq this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 20, no. 2, june, (2024), p p. 113 removal of diclofenac from contaminated water using organoclay as reactive material sara m. saadoon* , alaa kareem mohammed**, ziad t. abd ali***, israa m. rashid**** , wan nor roslam wan isaha***** and m. rahimnejad****** *,**,****department of biochemical engineering, al-khwarizmi college of engineering, university of baghdad, baghdad 47024, iraq ***department of environment engineering, college of engineering, university of baghdad, baghdad 47024 iraq *****department of chemical and process engineering, faculty of engineering and built environment, universiti kebangsaan malaysia, 43600 ukm bangi/ selangor, malaysia ****** department of chemical engineering, babol noshirvani university of technology, babol/ iran, p.o. box: 484, babol, iran *email: sara.fawzi1405@kecbu.uobaghdad.edu.iq corresponding auther: **email: dr.alaa@kecbu.uobaghdad.edu.iq ***email: z.tech2000@yahoo.com ****email: israa_msc2018@kecbu.uobaghdad.edu.iq *****email: wannorroslam@ukm.edu.my ******email: rahimnejad@nit.ac.ir (received 16 august 2023; accepted 13 december 2023; published 1 june 2024) https://doi.org/10.22153/kej.2024.12.001 abstract this study is concerned with the adsorption of diclofenac (dic) from polluted water using modified bentonite. hexadecyl trimethyl ammonium bromide (htab) was used to alter the hydrophilic nature of the bentonite to a hydrophobic one. various effecting parameters were investigated such as: contact time, ph, agitation rate, adsorption dosage,acidity ph, mixing time time, and initial adsorbate concentration (co). the best result obtained for the removal of diclofenac is 98% which occurred at 30 ppm initial concentration, acidity ph 7, 100 min mixing time, and o.3g/100ml (dic) dosage. langmuir isotherm model eas found the more suitable model to represent the adsorption process.on examining the kinetics of the adsorption process, the pseudo-second-order kinetic model well describes the experimental data. finally, thermodynamic investigations show that the adsorption process is endothermic, spontaneous as well as exhibited characteristics of physisorption. keywords: diclofenac; adsorption; modified – bentonite; isotherm; kinetics 1. introduction the issue of drug contamination in the water system and the subsequent heightened health risks stemming from improper drug disposal in aquatic habitats have emerged as significant concerns, mostly due to their adverse environmental consequences[1]–[3]. the primary sources of pharmaceutical residues in the environment are the human, veterinary, and pharmaceutical sectors. the release of therapeutic agents into surface water, groundwater, or drinking water can pose risks to individuals. this can occur through various means,including the direct release of veterinary medications,improper disposal of drugs,discharge of effluents from manufacturing plants, hospitals, and private residences, as well as the improper disposal of unused medications.[4], [5]. because mailto:sara.fawzi1405@kecbu.uobaghdad.edu.iq mailto:dr.alaa@kecbu.uobaghdad.edu.iq mailto:z.tech2000@yahoo.com mailto:israa_msc2018@kecbu.uobaghdad.edu.iq mailto:wannorroslam@ukm.edu.my mailto:rahimnejad@nit.ac.ir https://doi.org/10.22153/kej.2024.12.001 https://doi.org/10.22153/kej.2024.12.001 sara m. saadoon al-khwarizmi engineering journal, vol. 20, no.2, p.p. 113(2024) 2 these chemicals remain in the environment for a long time, are resistant to microbes, and may act together in harmful ways, they can have bad effects on aquatic life, even at very low levels [5], [6]. these effects can include disrupting hormones, halting reproduction, and affecting the ecosystem as a whole. in addition, it is very likely that organisms are constantly exposed to a variety of these substances throughout their lives, as pharmaceutical compounds are regularly discharged into the surrounding ecosystem.[7], [8]. pharmaceutical drugs with anti-inflammatory properties are commonly used due to their effectiveness in managing various forms of aches and pain. anti-inflammatory medications such as naproxen, diclofenac, piroxicam, and celecoxib have been around for a long time and are still in use. this is a big reason why aquatic ecosystems are so polluted[9], [10]. diclofenac (dic), a nonsteroidal anti-inflammatory drug is one of the most important medications, frequently used to treat pain and inflammation caused by migraines, arthritis, gout, and other diseases. [11], [12]. dic is commonly encountered in biosolids, surface water bodies, and wastewater systems. the aforementioned drug exhibits toxicity towards bacteria, invertebrates, and algae, and certain scholars have established a correlation between its usage and alterations in animal physiology [13], [14]. dic waste has been treated in several different ways, including electrochemical degradation [15], ozonation [16], advanced oxidation [17], nanofiltration [5], and photocatalytic degradation [18]. adsorption has been employed to handle dic waste[19], [20]. recent results revealed that the use of adsorption technique improved effectiveness in reducing the leakage of pollutants into the water system. [20], [21]. an active carbon prepared from apricot seed was used to remove dic from an aqueous solution [2]. another study used commercial activated carbon to remove diclofenac from synthetic water [22]. maia et al (2019) used commercial organoclay to remove dic [14]. different adsorbents have been employed in adsorption methods to remove pollutants like heavy metals, dyes, or antibiotics from municipal and industrial wastewater.[23], [24]. activated carbon is one of the substances that is most frequently utilized as adsorbents for the elimination of diclofenac [19]. however, there are several obstacles to employing activated carbon as an adsorbent, one of which is the high preparation cost [25], [26]. the use of bentonite as an adsorbent for the removal of hazardous compounds has received a lot of interest recently because it is an affordable material [13], [27]. the utilization of clays in pharmaceutical formulations induces modifications in the efficacy of the medication as a result of the interplay between the drug and clay constituents. interactions between clay minerals and medications have the potential to either enhance or diminish the bioavailability of drugs upon administration [24]. surfactants, such as htab [28], consist of molecules containing a hydrophilic quaternary ammonium group and a hydrophobic alkyl chain. addition of surfactants to bentonite increases the interlayer distance and number of reaction sites. this method of modifying clay alters its surface characteristics, transitioning it from being hydrophilic to progressively becoming hydrophobic, simultaneously enhancing its absorption capacities.[29]. recent research has shown that adding hexamethylammonium bromide (htab) to bentonite enhances the removal of antibiotics from aqueous solutions [30], [31]. the main objective of this study is to determine how well-modified bentonite acts as an effective and affordable adsorbent for the removal of diclofenac from contaminated aqueous solutions. moreover, this study aims to know the effect of operating factors (co, ph, clay dosage, contact time, and mixing time) on the efficiency of the removal process. 2. materials and methods 2.1 materials 2.2 cationic surfactant (htab) hexadecyl trimethyl ammonium bromide is a commonly used surfactant with a positive charge. it has a 16-carbon tail and an ammonium group head with three methyl groups attached [29]. this surfactant was used without additional purification. the chemical formula and structure of htab are shown in fig. 1. fig. 1. the chemical formula and structure of htab adsorbent: the study used iraqi bentonite, which was obtained in the form of rock pieces from the general company for geological survey and sara m. saadoon al-khwarizmi engineering journal, vol. 20, no.2, p.p. 113(2024) 3 mining in baghdad, as an absorbent material. the laboratories of the general company for geological survey and mining analyzed the chemical composition and physical properties of iraqi bentonite. the composition is shown in table 1. the surfactant used to denature natural bentonite (nb) was hexadecyltrimethylammonium bromide (htab). this surfactant, which was of analytical quality, was used without any further purification. adsorbate:the general corporation for pharmaceutical industries and medical supplies in samarra, iraq, supplied diclofenac. this material has been used in its original state without undergoing any additional processing. table 1, chemical composition of iraqi bentonite. 2.3 preparation of modified bentonite the following steps prepared the modified bentonite: (i) ten grams of natural bentonite (nb) were added to 200 ml ( i.e., weight ratio 1: 20 nb to water) of distilled water. (ii) the natural bentonite (nb) swelling well in distilled water after 2 hr. (iii) htab was added at a weight ratio of 0.37 g to each gram of bentonite and mixed for 2 hr. (iv) the resulting mixtures, modified bentonite, were washed with distilled water repeatedly to remove the excess salts and then dried in the oven at 105 ℃. (v) the dried mixtures were ground and sieved with a size range of 355 to 710 μm [29]. 2.4 adsorption experiment a series of batch experiments were conducted to investigate the adsorption behavior of diclofenac (dic) on the modified bentonite. the experiments were conducted using an orbital shaker to agitate a predetermined quantity of modified bentonite (mb) in a 50 ml solution of synthetic contaminants. the impact of several factors on the recovery of dic from an aqueous solution was studied. these factors included contact duration (ranging from 30 to 300 minutes), initial ph of the solution (ranging from 2 to 11), agitation speed (ranging from 0 to 270 rpm), initial concentration of dic (ranging from 10 to 200 ppm), and sorbent dosage (ranging from 0.1 to 0.8 g per 100 ml). next, the whatman filter paper was used to separate the adsorbent from the suspension. diclofenac concentration (dic) was determined using a dual uv spectrophotometer (uv model t80, england). the wavelength of the dic was determined to be 276.2 nm in a previous study [14]. the calculation of the fraction of dissolved noganic carbon (dic) removed by the microbial biomass (mb) was performed using equation (1) [32]. 𝑅 = [ 𝐶₀ − 𝐶𝑒 𝐶₀ ] x 100 % … (1) where r is adsorption percentage, 𝐶𝑜 and 𝐶𝑒 (mg/l) are the concentrations of diclofenac (dic) at initial and equilibrium conditions, respectively. eq. (2) is used to determine the adsorption capacity, qₑ (mg/g), at equilibrium conditions. [14]. 𝑞ₑ = (𝐶0 − 𝐶𝑒)𝑉 𝑚 … (2) 2.5 characterization of modified bentonite the morphology of the organic bentonite was examined using scanning electron microscopy (sem). a shimadzu ftir 8400s was used to analyze the functional group present on the surface of the adsorbent and to characterize both native and modified bentonite. this was done using kbr pellets in the wavelength range 400 4000 cm-1. 3 results and discussion 3.1 characterization 3.1.1 characterization using ft-ir ftir spectra were obtained by making measurements within the frequency range 400– 4000 cm-1, as shown in fig. 2. the experiment was performed using bentonite samples (natural and modified). natural bentonite (nb) displays large absorption bands at 3631 and 3440 cm-1, which can be attributed to the stretching vibrations of the oh bonds in the si-oh (silanol) and al-oh groups, respectively [29]. in addition, it is important to note that the occurrence of a large peak at 1031 cm-1 can be attributed to the presence of si-o-si groups located inside the tetrahedral sheets. after the natural bentonite alteration process, it was observed that the asymmetric stretching mode of si-o-si changed from 1028 to 1037 cm-1. moreover, it was discovered that the si-o-si deformation and bending modes, previously component composition wt% sio2 50.03 al2o3 16 cao 7.75 feo3 6.27 mgo 3.13 na2o 1.02 lo/1 11.43 sara m. saadoon al-khwarizmi engineering journal, vol. 20, no.2, p.p. 113(2024) 4 observed at frequencies of 790, 528, and 455 cm-1, respectively, were changed to frequencies of 786, 538, and 426 cm-1 for mb. the appearance of the corresponding peak at 1485 cm-1 in modified bentonite, which is absent in natural bentonite, indicates the presence of cn vibration in tertiary amines. after the modification process, the absorption band related to the –oh group and the bending vibration of h2o in natural bentonite (nb) saw a remarkable shift from 1650 cm-1 to a lower frequency of 1637 cm-1. this alteration signifies the removal of water molecules and change the hydrophobic characteristics of natural bentonite (nb). [33]. the modified bentonite exhibited peaks at 2850 and 2920 cm-1, which were attributed to the ch2 shear vibration band and ch3 symmetric stretching absorption band, respectively. fig. 2. ftir characterization bentonite ( natural (nb) and modified (mb). 3.1.2 sem analysis figure 3 displays the results of scanning electron microscopy (sem) performed on the clay. the surface morphology of natural bentonite (nb) underwent noticeable changes after being treated with hexamethylammonium bromide (htab). natural bentonite (nb) has a porous surface morphology that is characterized by uneven and rough optical properties. additionally, it showcases a scattered block structure of varied sizes. in contrast to the modified state of bentonite, which exhibits a surface morphology that resembles fragile, thin cornflakes or copious crystals with a fine texture. this observation implies that the surfactant has primarily coated the surface of the bentonite. the reduction in specific disordered structures commonly present in bentonite is accountable for the fluffy visual aspect [29] fig. 3. sem images of (a) natural bentonite (nb) (b) modified bentonite (mb). a b sara m. saadoon al-khwarizmi engineering journal, vol. 20, no.2, p.p. 113(2024) 5 3.2 batch experiments 3.2.1 effect of contact time the study investigated the impact of varying time durations, ranging from 30 to 300 minutes, on the recovery of the pollutant. the other conditions stayed the same during the whole experiment. these included the starting concentration of diclofenac (dic) at 30 ppm, the ph level at 7, the speed of the stirring at 200 rpm, and the amount of adsorbent used at 0.3 mg/100 ml. figure 4 illustrates the impact of contact time on the elimination of diclofenac. the study revealed that, as time progressed, there was a corresponding increase in the quantity of dic elimination. the initial removal efficiency exhibits a rapid rate, followed by a gradual decline until it stabilizes at a consistent level of 98% removal after 100 minutes [26]. the initial high adsorption rate of dic can be attributed to the swift diffusion of dic particles from the solution onto the exterior surfaces of the adsorbent. this phenomenon is facilitated by the abundance of polarization groups present in the composition of dic pollutant molecules [2]. fig. 4. effect of time on removal percentage. 3.2.2 effect of solution ph measuring the ph in the aqueous solution is a crucial factor to consider in the adsorption process. the study investigated the impact of ph on the elimination of dic throughout a ph range of 2 to 11. the remaining variables, including contact time (100 minutes), agitation speed (200 rpm), initial concentration (30 ppm), and adsorbent dosage (0.3 grams per 100 milliliters), were held constant a 0.1 m solution of hydrochloric acid (hcl) and sodium hydroxide (naoh) were employed to adjust the ph of the solution. based on the results depicted in figure 5, the percentage of dic removal stayed consistent at 98% across all tested ph values. this indicates that dic removal is mostly unaffected by the ph levels of aqueous solutions. the observed phenomenon can be attributed to the use of a surfactant template, which creates an electrostatic attraction between the anionic groups of dic and the quaternary ammonium groups present in the bentonite layers. [32]. ibrahim ziad (2020) showed similar patterns in the elimination of acidic dye using bentonite treated with cetyltrimethylammonium bromide [29]. ph fig. 5. effect of solution ph on removal percentage. 3.2.3 agitation speed to investigate the influence of agitation speed on the adsorption of dic onto modified bentonite, a series of experiments were conducted using different agitation speeds, ranging from 0 to 270 rpm. based on the data presented in figure 6, it can be observed that the absorption dic exhibited a positive correlation with the agitation speed. notably, the highest absorption rate of dic was achieved at an agitation speed of 200 rpm, reaching a peak value of 98%. the increase in dic removal remains unaltered when values exceeding 200 rpm are applied. the observed phenomenon can be attributed to the resistance encountered by the adsorbate as it traverses the boundary layer within the liquid phase en route to the solid surface of the adsorbent, particularly at low agitation rates. increasing the stirring speed leads to a decrease in the thickness of the boundary layer. the decrease in thickness reduces the resistance that occurs during mass transfer of the adsorbent, thus accelerating the adsorption process. the observed result is attributed to the increased film thickness on the solid surface, indicating that film diffusion is the limiting factor in the overall absorption rate [24]. 0 20 40 60 80 100 0 50 100 150 r e m o v a l % time (min) 70 75 80 85 90 95 100 0 1 2 3 4 5 6 7 8 9 10 11 12 r em o v al % sara m. saadoon al-khwarizmi engineering journal, vol. 20, no.2, p.p. 113(2024) 6 fig. 6. effect of agitation speed on removal percentage. (co = 30 ppm, ph =7, time = 100 min and adsorbent dose= 0.3g/100ml). 3.2.4 initial pollutant concentration the adsorption process of modified bentonite is significantly affected by the initial concentration of dissolved inorganic carbon (dic). an investigation was performed using different initial concentrations of adsorbents, ranging from 10 to 200 ppm. figure 7 shows the effect of starting concentration on the removal of dissolved inorganic carbon (dic). the removal efficiency showed a positive correlation with the initial concentration, i.e. within the range of 10 to 30 ppm. the highest removal efficiency approaching 98% was achieved at an initial concentration of 30 ppm.. as a result, the effectiveness of removal has declined. the observed trend can be explained by the large proportion of available active sites on bentonite compared to the initial number of dissolved inorganic carbon (dic) molecules at low adsorption concentrations. as a result, the removal efficiency is large. at larger initial concentrations, the amount of (dic) surrounding the bentonite active sites will increase. as a result, the number of available adsorption sites on bentonite will decrease, resulting in decreased dic removal effectiveness [11]. fig. 7. effect of initial concentration on removal percentage. 3.2.5 modified bentonite dosage research was conducted to examine the effect of different amounts of modified bentonite on the adsorption process. doses ranged from 0.1 to 0.8 grams / 100 ml of dic solution. the remaining parameters were kept constant at c₀ concentration = 30 ppm, ph level 7, for 100 min, and a stirring speed of 200 rpm. the data shown in figure 8 show a clear relationship between the dose of modified bentonite and the percentage of removal. as the dose of modified bentonite increases, the removal percentage also increases. at a dose of 0.3 g/100 ml of diclofenac solution, the bentonite clearance stabilizes at a constant value of 98%. increasing the amount of adsorbent will enhance the number of active sites on the bentonite, leading to increased adsorption of dic molecules and thus improving the removal efficiency of the adsorbent. the results of khan and hegde (2018) [33] are consistent with our results, where they showed that increasing the clay dosage enhances the adsorption efficiency. this can be attributed to the enlarged surface area of the modified bentonite, which facilitates the removal of cadmium from wastewater. 0 20 40 60 80 100 120 0 50 100 150 200 250 300 r em o v al % agitation speed (rpm) sara m. saadoon al-khwarizmi engineering journal, vol. 20, no.2, p.p. 113(2024) 7 fig. 8. effect of the adsorbent dosage on removal percentage%. adsorption isotherms the adsorption equilibrium was examined using two specific adsorption isotherms: langmuir isotherm and freundlich isotherm. the langmuir isotherm is derived from the concept of monolayer adsorption, which refers to the adsorption process that takes place exclusively on the surface of the adsorbent, where there are a limited number of adsorption sites. the mathematical representation of the langmuir isotherm is defined by equation 3. [26]. 𝑞𝑒 = 𝐾𝐿 𝑞𝑚 𝐶𝑒 1 + 𝐾𝐿𝐶𝑒 … (3) the linearized form of eq. (3) is given by eq. (4) 1 𝑞𝑒 = 1 𝑞𝑚 + 1 𝑞𝑚𝐾𝐿 1 𝐶𝑒 … (4) equation (4) was used to determine the values of 𝐾𝐿and 𝑞𝑚. the freundlich isothermal model is based on the hypothesis of diverse surface energies and the occurrence of multilayer adsorption. the freundlich isotherm is represented by equation (5) [5]. 𝑞𝑒 = 𝐾𝐹𝐶𝑒 1 𝑛 … (5) the linearization form of the freundlich model can be expressed as in eq.(6). ln(𝑞𝑒) = ln(𝐾𝐹 ) + 1 𝑛 ln(𝐶𝑒) … (6) the constant parameters of the freundlich isotherm, namely 𝐾𝐹 and 𝑛, correspond to the adsorption capacity and adsorption density, respectively. experimental data can be used to predict these values using equation (6). figure 9 displays the correlation of the experimental data with the langmuir and freundlich isotherm models. fig. 9. linear form of the isotherm models for sorption of diclofenac onto modified bentonite, (a) langmuir, (b) freundlich. table (2) displays the values of qm, kl, n, and kf as well as the values of the correlation coefficients 𝑅2. table 2, parameters of langmuir and freundlich equations langmuir freundlich 𝐾𝐿 𝑞𝑚 𝑅2 𝐾𝐹 n 𝑅2 (l/mg) (mg/g) 0.408 22.935 0.9354 7.49 2.865 0.8697 sara m. saadoon al-khwarizmi engineering journal, vol. 20, no.2, p.p. 113(2024) 8 based on the values of the correlation coefficients (𝑅2), it can be concluded that the langmuir model provides a better fit to the experimental data compared to the freundlich model. this indicates that diclofenac binds to modified bentonite in a monolayer manner. the dimensionless constant 𝑅𝐿 serves as a reliable indication of the langmuir isotherm. the value of 𝑅𝐿 can be determined by utilizing equation (7). [34]: 𝑅𝐿 = 1 1 + 𝐾𝐿 𝐶𝑜 … (7) 𝑅𝐿 values are used to describe whether the adsorption is favorable when 𝑅𝐿 < 1, linear when 𝑅𝐿 = 1, unfavorable when 𝑅𝐿 > 1, or irreversible when 𝑅𝐿 = 0 𝑅𝐿 = 1 1 + 𝐾𝐿 𝐶𝑜 = 1 1 + 0.408(30) = 0.075 < 1 then, the adsorption is favorable. 3.3 adsorption kinetics adsorption kinetic study is highly important in the design and evaluation of adsorbents for removing sorbates from the aqueous solution. the pseudo-first-order and pseudo-second-order models were employed to correlate the kinetics data. equations (8) and (9) represent the differential equations of pseudo-first-order and pseudo-second-order kinetics, respectively [35]. ( 𝑑𝑞𝑡 𝑑𝑡 ) = 𝐾1 (𝑞𝑒 − 𝑞𝑡) … (8) 𝑑𝑞𝑡 𝑑𝑡 = 𝐾2(𝑞𝑒 − 𝑞𝑡)2 … (9) the linearized forms of eqs. (8) and (9) are given by eqs. (10) and (11), respectively. 𝑙𝑛(𝑞𝑒 − 𝑞𝑡) = ln 𝑞𝑒 − 𝐾1𝑡 … (10) 𝑡 𝑞𝑡 = ( 1 𝐾2𝑞𝑒 2) + ( 𝑡 𝑞𝑒 ) … (11) as shown in figure 10, the parameters for each model were determined by fitting the linearized form of these models to the experimental data. table 3 displays all parameters with the empirical coefficients derived from the linear plot's slope and intercept using microsoft excel 2016 software. regardless of the magnitude of r2, it is evident from figure 10 and table 3 that the sorption of dic is likely to be second-order because the experimental value 𝑞𝑒 (19.54 mg/g) was closer to the calculated value of 𝑞𝑒 (19.72 mg/g) for the second-order model than for the first-order model (20.45 mg/g ). these results indicate that chemosorption or ion exchange mechanisms predominated in the sorption of dic on modified bentonite. these findings align with the findings of other researchers such as [29], [36], and [37]. fig. 10. (a) pseudo-first-order and (b) pseudo-second-order kinetics models for adsorption of diclofenac onto modified bentonite. sara m. saadoon al-khwarizmi engineering journal, vol. 20, no.2, p.p. 113(2024) 9 table 3, adsorption kinetics parameters of pseudo first-order and pseudo second-order rate equations pseudo-first-order pseudo-second-order 𝐾1 𝑞𝑒 𝑅2 𝐾2 𝑞𝑒 𝑅2 (min-1) (mg/g) (g/mg. min) (mg/g) 0.0638 20.45 0.9675 0.00292 19.72 0.994 3.4 thermodynamics study the thermodynamic properties of dic adsorption on modified bentonite were studied by analyzing three thermodynamic parameters: enthalpy change (∆𝐻0), gibbs free energy change (∆𝐺0), and entropy change ((∆𝑆0 ). the gibbs free energy conversion ((∆𝐺0) calculation was performed using equation (12) [36]. ∆𝐺𝑜 = −𝑅 𝑇 𝑙𝑛(𝐾𝑐) … (12) the values of 𝐾𝑐 can be calculated by eq. (13) 𝐾𝑐 = 𝑞𝑒 𝐶𝑒 … (13) the relationship between the thermodynamic parameters, namely enthalpy change (∆𝐻𝑜), entropy change (∆𝑆𝑜), and gibbs free energy change (∆𝐺𝑜), is defined by equation (14) [38]. ∆𝐺𝑜 = ∆𝐻𝑜 − 𝑇∆𝑆𝑜 … (14) substitution eq. (14) in eq. (12) gives ln 𝐾𝑐 = ∆𝑆° 𝑅 − ∆𝐻° 𝑅𝑇 … (15) the equilibrium constant ln (𝐾𝑐) was calculated using equation (13) at different temperatures. using equation 15, the enthalpy (∆𝐻𝑜) and entropy (∆𝑆𝑜 ) were determined by slope and intercept analysis, respectively. figure 11 shows a decrease in 𝐾𝑐 values as the temperature increases from 30 to 50 °c. table 4 presents the thermodynamic parameters ∆go, ∆ho and ∆so at different temperatures for the adsorption of diclofenac on modified bentonite. fig. 11. 𝐥𝐧 𝐊𝐝 versus 𝟏 𝐓 for the adsorption of dic on modified bentonite. table 4, thermodynamic parameters for the adsorption of diclofenac onto modified organobentonite. the change in free energy ∆𝐺𝑜 was calculated to be 6.294, 5.208, and 4.122 kj/mol at 30, 40, and 50oc, respectively. the spontaneous and thermodynamically viable character of the adsorption process was indicated by the negative ∆𝐺𝑜 values. the decrease in ∆𝐺𝑜 values with increasing temperature indicates that adsorption at elevated temperatures is less feasible. the enthalpy of adsorption was determined to be -39.2 kj/mol. the negative value of ∆𝐻𝑜 indicates the exothermic nature of the adsorption, and its magnitude provides information on the type of adsorption, which can be physical or chemical. ∆𝐻𝑜 values for physical adsorption are less than 40 kj/mol, according to previous studies [39], [40]. the adsorption of dic onto mb can therefore be classified as physisorption. it was determined that the so parameter for dic adsorption was 108.6 j/mol k. the negative value of ∆𝑆𝑜 indicates a reduction in randomization at the solid/solution interface during the adsorption process. 4. conclusions the modified bentonite demonstrated significant efficacy in the removal of diclofenac (dic) from an aqueous solution, with a maximum removal rate of 98%. the percent removal of ∆𝑮𝒐 (kj/mol) ∆𝑺𝒐 (j/mol. k) ∆𝑯𝒐 (kj/mol) 𝟑𝟎 𝒐𝑪 40 𝑜𝐶 50 𝑜𝐶 -6.294 -5.208 -4.122 -108.6 -39.2 sara m. saadoon al-khwarizmi engineering journal, vol. 20, no.2, p.p. 113(2024) 10 dissolved diclofenac (dic) was influenced by many parameters, like ph, co, adsorbent dosage, agitation speed, and contact time. it was shown that variations in ph did not significantly impact the removal efficiency. the optimal values for these parameters, which resulted in the highest level of recovery, were determined to be a contact period of 100 minutes, an initial concentration of 30 parts per million (ppm), an agitation speed of 200 revolutions per minute (rpm), and an adsorbent dosage of 0.3 grams per 100 milliliters (g/100 ml). based on the isotherm analysis, it was observed that the adsorption data exhibited a stronger correlation coefficient (r2 = 0.9354) with the langmuir isotherm model compared to the freundlich isotherm model (r2 = 0.8692). the results of the kinetic analysis confirm that chemisorption has been the dominant process (r2 = 0.994). this is supported by the observation that the experimental data adhered to a pseudo-secondorder model rather than a pseudo-first-order model. based on thermodynamic investigations, it was shown that the adsorption process is physisorption and had endothermic characteristics, as well as occurring spontaneously. references [1] i. m. rashid, s. d. salman, and a. k. mohammed, “removal of pathogenic bacteria from synthetic contaminated water using packed bed silver nanoparticle-coated substrates,” energy, ecology and environment, vol. 6, no. 5, pp. 462–468, oct. 2021, doi: 10.1007/s40974-021-00208-3. 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(2024) 1-13، صفحة 2، العدد20مجلة الخوارزمي الهندسية المجلد سارة مرتضى سعدون 13 ستخدام الصلصال العضوي كمادة تفاعليةاازالة الديكلوفيناك من المياه الملوثة ب ،زياد طارق عبد علي*** ، **عالء كريم محمد ،* سارة مرتضى سعدون ******مصطفى رحيم نجاد، ***** وان نور روسالم ، ****إسراء مزاحم رشيد العراق ،جامعة بغداد ،كلية الهندسة الخوارزمي ،قسم الهندسة الكيميائية االحيائية **، *****، جامعة بغداد ،كلية الهندسة ،*** قسم هندسة البيئة الجامعة الوطنية الماليزية ،كلية الهندسة والبيئة ،قسم الهندسة الكيميائية والعمليات** *** ايران ،جامعة بابول ،قسم الهندسة الكيمياوية ** *** sara.fawzi1405@kecbu.uobaghdad.edu.iq:البريد اإللكتروني * dr.alaa@kecbu.uobaghdad.edu.iq:البريد اإللكتروني ** z.tech2000@yahoo.com:البريد اإللكتروني *** israa_msc2018@kecbu.uobaghdad.edu.iq:البريد اإللكتروني**** wannorroslam@ukm.edu.my:البريد اإللكتروني***** rahimnejad@nit.ac.ir:البريد اإللكتروني ****** المستخلص تم تغيير البنتونايت وقد ( من المياه الملوثة عن طريق االمتزاز على البنتونيت المعدل. diclofenacازالة المادة الدوائية الديكلوفيناك ) تمفي هذه الدراسة ، استخدمت التجارب الدفعية لدراسة تأثير عدد من لقد (. htabمن مادة محبة للماء إلى كارهة للماء باستخدام بروميد األمونيوم ثالثي ميثيل هيكساديسيل ) ( ، co) االبتدائي للملوث تركيز ال، و الخلطللمحلول ، وسرعة (phكفاءة عملية االمتزاز. هذه العوامل هي: زمن التالمس ، ودرجة الحموضة ) فيالعوامل دقيقة ، ودرجة 100: زمن التالمس عند القيم التالية للعوامل المؤثرة( ٪98)بحدود اك تم تحقيق أقصى إزالة للديكلوفين وقد.المستخدمة المادة الممتزة كميةو مل 100م بينتونيت لكل غ 0.3في المليون ، والجرعة الممتزة ا جزء 30 وتركيز ابتدائي للمادة الملوثة دورة في الدقيقة ، 200، وسرعة الخلط 7الحموضة ( ftir( والتحليل الطيفي لألشعة تحت الحمراء لتحويل فورييه )semالفحص المجهري اإللكتروني للماسح الضوئي ) تم استخدامومن المحلول الملوث. من التي تم الحصول عليها البيانات التجريبية لتمثيلهو األنسب langmuir وجد ان موديل وقد.(البنتونايت المعدل لتشخيص صفات المادة الممتزة ) من كانت عملية االمتزاز وووجد انها تتمثل بشكل جيد بتفاعل زائف من الدرجة الثانية. حركية عملية االمتزاز دراسة تتم وقد.المختبر التجارب العملية في ماصة للحرارة وتلقائية ، وفق ا لتحليالت الديناميكا الحرارية.النوع الفيزياوي فضال عن كونها mailto:sara.fawzi1405@kecbu.uobaghdad.edu.iq mailto:dr.alaa@kecbu.uobaghdad.edu.iq mailto:z.tech2000@yahoo.com mailto:israa_msc2018@kecbu.uobaghdad.edu.iq mailto:wannorroslam@ukm.edu.my *,**,****department of biochemical engineering, al-khwarizmi college of engineering, university of baghdad, baghdad 47024, iraq ***department of environment engineering, college of engineering, university of baghdad, baghdad 47024 iraq *****department of chemical and process engineering, faculty of engineering and built environment, universiti kebangsaan malaysia, 43600 ukm bangi/ selangor, malaysia ****** department of chemical engineering, babol noshirvani university of technology, babol/ iran, p.o. box: 484, babol, iran *email: sara.fawzi1405@kecbu.uobaghdad.edu.iq sara.fawzi1405@kecbu.uobaghdad.edu.iq: البريد الإلكتروني* dr.alaa@kecbu.uobaghdad.edu.iq: البريد الإلكتروني** this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 19, no. 4, december, (2023) p. p. 1628 the remediation of congo red-contaminated groundwater by using a permeable reactive barrier through modified waterworks sludge mgal-ldh sudad adil salih* tariq m. naife** *,** department of chemical engineering/ university of baghdad/ baghdad/ iraq corresponding author *email: sudad.saleh1607m@coeng.uobaghdad.edu.iq **email: tariq.mohammed@coeng.uobaghdad.edu.iq (received 16 may 2023; accepted 5 july 2023) https://doi.org/10.22153/kej.2023.07.001 abstract this investigation aims to explore the potential of waterworks sludge (ws), low-cost byproduct of water treatment processes, as a sorbent for removing congo red (cr) dyes. this will be achieved by precipitating nano-sized (mgalldh)-layered double hydroxide onto the surface of the sludge. the efficiency of utilizing mgal-ldh to modify waterworks sludge (mws) for use in permeable reactive barrier technology was confirmed through analysis with fourier transform infrared and x-ray diffraction. the isotherm model was employed to elucidate the adsorption mechanisms involved in the process. furthermore, the comsol model was utilized to establish a continuous testing model for the analysis of contaminant transport under diverse conditions. a strong correlation was indicated, with a coefficient of determination (r2) ≥ 0.97, when the model's predictions were compared to experimental values, indicating the accuracy of the model. continuous transport exhibited earlier breakthrough points when the bed depth decreased and the initial concentration and flow rate increased. keywords: layered double hydroxide, waterworks sludge, congo red. 1. introduction groundwater, being one of the most abundant water sources, is often regarded as a more dependable option compared to surface water for a variety of applications [1]–[3]. the contamination of this valuable resource is a significant environmental concern, as the majority of pollutants resulting from human activities or unnatural sources can have long-lasting and detrimental effects [4]–[7]. aromatic molecular structures present in dyes pose a considerable challenge for biodegradation into environmentally benign compounds and can have severe toxicity towards various microorganisms [8], [9]. with its anionic and acidic properties, cr can act as an antifungal therapeutic agent in various fields, such as commercial fish hatcheries and animal husbandry [10]–[12]. however, it can have adverse effects on humans, such as amyloidosis [13]; as a result, it has been banned in europe, the united states, canada, and other parts of the world [14]. to guarantee the safe disposal of wastewater, it is essential to eliminate cr from it. several physical and chemical methods have been employed for this purpose, such as coagulation and flocculation, which are used for removing dyes from wastewater [15], biological degradation[14], adsorption [16], membrane filtration [17], [18], and ultra-chemical filtration [1], [19]. although these methods are effective, they have technical limitations such as high costs, low processing capacity, and the potential for secondary pollution. the effectiveness, simplicity, and versatility of adsorption make it widely recognized as the optimal method for the removal of cr dye. while mailto:sudad.saleh1607m@coeng.uobaghdad.edu.iq mailto:tariq.mohammed@coeng.uobaghdad.edu.iq https://doi.org/10.22153/kej.2023.07.001 sudad adil salih al-khwarizmi engineering journal, vol. 19, no. 4, p.p. 1628 (2023) 17 various adsorbents have been explored, including activated carbons [20] and natural biosorbents [21], they often fail to meet the requirements for cr dye removal due to low adsorption capacity, long diffusion times, or poor structural stability. investigating advanced adsorbents that can efficiently capture cr dye is crucial. permeable reactive barriers (prbs) have demonstrated the potential to restrict and contain contaminant migration, protecting water resources. choosing the appropriate material for prbs is crucial, as it must be reactive and possess permeability that matches or surpasses that of the surrounding aquifer. furthermore, innovative remediation techniques are required to treat groundwater contaminated with heavy metals and other pollutants [22]–[24]. millions of tons of waterworks sludge (ws) are generated annually in europe [8], [9], with the potential for a significant increase in the future. although classified as "non-hazardous" under eu regulations, sludge disposal in sanitary landfills can result in increased costs in some countries. conversely, in other countries, the direct discharge of sludge into rivers has caused a significant rise in surface water turbidity. this study aims to address this issue by developing a novel sorbent. the sorbent will be created by coating ws with layered double hydroxide (mws) to efficiently remove cr dyes. the efficacy of the composite material will be assessed through two main steps: first, by determining the mechanisms involved in dye removal using xrd and ft-ir analysis, and second, by tracking the migration of the dye front through a physical column filled with the prepared sorbent and mathematically describing this movement using solute transport equations. 2. mathematical model 2.1 adsorption isotherms the adsorbate concentration in the state of the liquid and its concentration on the adsorbent surface at a particular temperature are related by the isotherm model, which is frequently utilized to explain adsorption. the equilibrium concentration of the adsorbate in solution (ce) (mg/l) is shown against the amount of adsorbate per unit mass of adsorb (qe) (mg/g). this number is typically uniformed by the quantity of adsorbent to make comparisons with various substances simple. adsorbent concentration is not increasing proportionally to the amount of adsorbed material per unit mass of adsorbent.this research utilized various adsorption isotherm models, and a brief overview of these models is presented below. a favorable isotherm is one that is upwardly convex, indicating that the solid content remains relatively high even at low concentrations in the liquid. the first non-linear isotherm was introduced by freundlich and kuster.in order to characterize the dispersion of chemicals between the two states of matter, irving langmuir developed a non-linear model in 1916. [25]: qe = kfce 1 n⁄ … (1) qe = qmbce 1+bce … (2) where kf (mg/g)(l/mg)1/n and n are freundlich constants related to adsorption capacity and adsorption intensity, respectively. qm (mg/g) and b (l/mg) are used to describe the maximum adsorption capacity and energy of adsorption, respectively. 2.2 modeling of dissolved contaminants three fundamental processes govern the transportation of contaminants in the subsurface environment, as stated by [26]: molecular diffusion, advection, and mechanical dispersion. 1. molecular diffusion: fick's first law defines the diffusion of solutes, where the movement of solutes is from high concentration regions to low concentration regions. the quantity of transported solute is proportional to its concentration and can be mathematically expressed in one dimension [27]. f = −dd ( dc dx ) …(3) where f refers to solute mass flow per unit area (kg /(m2 s)), dd for diffusion coefficient (m2/s), c for solute concentration (mg/l), and dc/dx for concentration gradient per unit length. fick's second law [28] should always be applied in situations where concentration may evolve over time: ∂c ∂t = dd ∂2c ∂x2 … (4) diffusion in porous media is slower than in water because the ions must travel along longer paths as they pass through mineral-solid grains. furthermore, diffusion can only occur through pore holes. to address this, an efficient diffusion coefficient can be used [27]: d∗ = τdd … (5) where τ is a tortuosity factor and its values ranged from 0.01 to 0.5 [27]. 2. advection: is the process that moves contaminants through the groundwater. the rate of sudad adil salih al-khwarizmi engineering journal, vol. 19, no. 4, p.p. 1628 (2023) 18 advection and the flow rate of groundwater are the same. the darcy velocity (v) (m/s) is the same as the actual velocity (va) (m/s), which is related to porosity (n). the advictive flux (fa) is calculated as follows [27]: fa = vac = v n c … (6) mechanical dispersion: occurs when water containing the chemical(s) flows around the soil grains in the aquifer, resulting in mixing. molecules of water actually move more quickly and slower than the average linear velocity due to three factors: fluid moves faster in the centre of pores than at the edges, some molecules follow longer discrete paths, and several voids are larger than others, allowing faster flow. mechanical mixing appears to happen along the flow path because water molecules don’t move at the same velocity. this mixing (or dispersion) can dilute the solute at the propagating edge of flow through longitudinal and transverse dispersions. separating the mechanisms of mechanical dispersion and diffusion in swirling groundwater is unfeasible. they're categorized together and referred to as "hydrodynamic dispersion" as follows [27]: dl = αlvl + d∗ … (7) where l and t stand for longitudinal and transverse dispersivities, respectively, the coefficients of longitudinal and transverse hydrodynamic dispersions are denoted as dl and dt(m2/s). in the subsurface environment, chemical reactions can lead to changes in a compound's properties, conversion into a different form, or reaction with other chemicals. isotherms, which consider how the concentrations of the reactants impact the reaction rate, are widely used to explain these processes [29]. sorption is the most valuable chemical reaction in the subsurface environment for the transport of inorganic and organic impurities. sorption represents the solute adhering to the surfaces of solid particles, causing it to take longer to arrive. the flow of an individual dissolved component into and out of a mws elemental control volume, f, is taken into account by the mass conservation equation, which is provided by: −( ∂f ∂x + ∂f ∂y + ∂f ∂z ) ∓ r = ∂m ∂t = ∂(nc) ∂t …(8) where r is the reaction term, which may be either a (+) source or a (-) sink for the solute and m is the mass per unit volume. eq. 9 can be written as follows after substitution of advective flux (=vx n c) and dispersive flux (=-ndx ∂c ∂x ): − [ ∂ ∂x (vxnc − ndx ∂c ∂x )] − [ ∂ ∂y (vync − ndy ∂c ∂y )] − [ ∂ ∂z (vznc − ndz ∂c ∂z )] ± r = ∂(nc) ∂t …(9) by considering a steady flow velocity, dispersion coefficient, and porosity, the well-known advection-dispersion formula could potentially be utilized to determine the 1 d mass transport of a solute in the saturated zone [27]. dz ∂2c ∂z2 − vz ∂c ∂z ± r n = ∂c ∂t … (10) the specific form of eq. 11 is determined by the outcome term's shape. perhaps the most frequent mass transfer process what occurs in the transportation of mass is adsorption, which tends to be the main mechanism for the operation of prbs the following equation can be used to determine r's value [30]: r = ρb ∂q ∂t … (11) eq.11 can be integrated with eq.15 to obtain the following equation [31]: dz ∂2c ∂z2 − vz ∂c ∂z = ∂c ∂t + ρb n ∂(q) ∂t … (12) where ρb is the dry bulk density and q is the solute concentration sorbed on the sorbent. the langmuir or freundlich isotherm model can be used to describe the values of q (mg/g) as a function of concentration. eq.12 can be rewritten as follows: dz ∂2c ∂z2 − vz ∂c ∂z = r ∂c ∂t …(13) the retardation factor (r) is used to describe the decrease in solute transport in relation to advection. the advection-dispersion equation (ade) can be used to determine the one-dimensional mass transport of solute in the saturated zone, assuming constant flow velocity, dispersion coefficient, and porosity. boundary and initial conditions that describe the physical state of the process must be provided to fully define the equation. the boundary conditions represent the geometry of the flow domain and the values of the dependent variable or its derivative [32]. numerical models for solute transport are useful in designing remedial programs as they provide valuable information about mass transport. these models divide the flow region into finite elements or grid cells, with each element representing a bounded portion of the flow region. the solution obtained for each element depends on adjacent segments as well as a set of auxiliary conditions that describe the domain geometry, variables, boundary conditions, and initial values. numerous numerical techniques, including the boundary element technique,the finite difference method, and finite element procedure, are currently being produced. groundwater transport formulas are discretized utilizing the finite element method sudad adil salih al-khwarizmi engineering journal, vol. 19, no. 4, p.p. 1628 (2023) 19 (fem), which produces a set of algebraic differential equations. mathematical techniques are able to be utilized to solve these types of issues [33]. in the current work, a partial-differential equation (pde) governing the transient transport of cr in the saturated zone (eq. 13) has been calculated using the finite element method followed by a solution with comsol multiphysics 3.5a. the pde was solved using the "earth science module" of the software in the "saturated solute transport" option. 2.3 coefficient of dispersion to measure the coefficient of hydraulic conductivity in the direction of flow, a tracer experiment was conducted on a column packed with 0.5 m of dry reactive material. water was injected in an upward direction to avoid entrapping air in the voids between solid grains. for the tracer experiment, one gram of nacl was dissolved in deionized water (1 l), which was subsequently injected at flow rates between 5 and 20 ml/min into the packed column. nacl was selected because of its accessibility, safety, and simplicity of detection. electrical conductivities corresponding to nacl concentrations were measured at certain time intervals during the experiment, and these values were used to determine the coefficient of dispersion in the longitudinal direction (dl) using the following equation [34]: dl = 1 8 [ (zo−vt0.16) (t0.16)0.5 − (zo−vt0.84) (t0.84)0.5 ] 2 …(14) here, zo represents the bed depth (0.5 m), v is the velocity in the voids, and t0.84 and t0.16 are times corresponding to 84% and 16% of c/co, respectively. 3. experimental work 3.1 materials and methods the research concentrated on cr dyes that were procured from the himedia company in india. to prepare the initial dye solution, a specific amount of cr was mixed with distilled water (1 liter), resulting in a solution with an cr concentration (1000 mg/l). a dilution was employed to obtain various concentrations of the dye in the water samples. to adjust the ph of the samples, drops of hcl or naoh(1 m) were added. the sludge was obtained from the water treatment (al-weihdaa) in baghdad, iraq. during treatment, alum salts were added to the sedimentation tank. the sludge was dried for several days and then ground into a fine powder. in addition to characterization using ftir, the hydraulic conductivity of the sludge was also measured and found to be low at 0.0245 cm/s. this low hydraulic conductivity may result in blockages during continuous flow in a prb. coarse sand was employed in various proportions along with the sludge to enhance hydraulic conductivity, aiming to overcome the inherent low hydraulic conductivity of the sludge. the sand used in the experiment had a particle size ranging between 1.7 and 3.15 mm. 3.2 modification of ws to create an affordable sorbent with enhanced reactivity, ws was employed as a matrix for immobilization, and its surface was subsequently coated with nanoparticles of layered double hydroxide (mg/al-ldh). the procedure involved mixing 25 ml each of magnesium nitrate hexahydrate (0.1 m) and aluminium nitrate nonahydrate (0.05 m) and adjusting the ph to 11 using 1 m nh4oh. ws was added to synthetic new functional groups, and the resulting sorbent was washed with water until the ph reached 6.5-7. through the application of (mg/al)-layered double hydroxide (ldh) nanoparticles, the ws underwent a transformation, resulting in the formation of modified ws (mws) with a coated surface. xrd and ft-ir were utilized to analyze the coating method and to find any functional groups in the mws. the efficacy of the mws in removing cr dyes from contaminated water was evaluated through analysis of the dye concentration, with the experimental methods and setup described in detail to ensure accurate measurements. 3.3 characterization xrd analysis was conducted using the d/max 2500 v/pc from rigaku, japan, to identify the coated and virgin ws crystal structures. ft-ir analysis was conducted to identify the functional groups that improve the sorption capacity of the prepared sorbent. the analysis was carried out using a bruker tensor 27 spectrophotometer with the kbr pellet technique, and the spectra were recorded in the range of 4000 to 400 cm-1. 3.4 continuous study the reactivity of the filler material in removing cr from contaminated water was evaluated using a number of column tests. the sorbent's efficiency was evaluated based on its ability to eliminate sudad adil salih al-khwarizmi engineering journal, vol. 19, no. 4, p.p. 1628 (2023) 20 pollutants. a column experiment was performed to evaluate the reactivity and hydraulic performance of mws. the column was 2 and 50 cm in diameter and height, respectively, with sampling ports (p1 to p6) located every 5 cm from the bottom, covered by plastic valves. in order to prevent the trapping of air between the particles, the mws was carefully introduced into the column, and distilled water was slowly introduced from the bottom using a peristaltic pump. the tests performed in the column lasted 90 hours and throughout that time the amount of cr in the effluent water was continuously monitored. the samples of water were promptly analyzed with the help of a uvspectrophotometer [4]. fig. 1. details of continuous study. 4. results and discussion 4.1 adsorbent characteristics the xrd spectrum in fig. 2 shows the crystal structure of mws. in order to compare the crystalline structures of the composite sorbent and sludge, xrd analysis was conducted on both materials, and their profiles are depicted in fig. 2 alongside the joint committee on powder diffraction standards (jcpdss). the analysis indicated that iron oxide, calcite, and silica oxide are the primary components of ws. however, the mws xrd pattern showed a new peak at 18.01, 26.6, and 34.1°, suggesting the existence of mg/fe crystals. the findings indicate that the mws sorbent's synthesis was successful [35]–[40]. fig. 2 displays the infrared spectra of ws, mws, cr dye, and the sorbent after adsorption within the 400 to 4000 cm-1 range. the significant peak at 3491 cm1 represents the stretching vibration of interlamellar water-linked -oh groups, o-h groups of adjacent layers, and physically adsorbed water. bound h2o has been detected demonstrated by the shift at 1648 cm-1. the relationship with cr is confirmed by the raman spectra of -oh at 3491 cm-1. o-m-o and m-o (where m is a metal) vibrations in the lattice frequently correspond to the peak that is nearest to 531 cm-1. the effective modification of ws is further demonstrated by the identification of a new peak at 1348 cm1 in the mws compared with ws, that corresponds to the co32's in-of-plane vibration band with an asymmetric stretch absorption band. after cr adsorption, two separate peak shapes near 1080 and 1159 cm-1, that relate to the vibrations of the s=o and aromatic ring structures of the cr, accordingly, were observed. these results indicate that coated ws surfaces are successful in adsorbing cr. 4.2 sorption isotherm models when equilibrium occurs in the procedure of adsorption, the adsorption isotherm can potentially be utilized to determine how cr are distributed throughout the mws and water phases. moreover, this isotherm can also be used to find out the highest amount of adsorbate that can be adsorbed and the attraction of the adsorbent towards the adsorbate [41], [42]. in the present study, two commonly utilized sorption isotherm models— langmuir and freundlich—were utilized to correlate with the experimental data from research on adsorption on mws. the experiments were conducted under optimal conditions with selected contaminants at varying concentrations. during the preparation process, mixing speed and time were critical factors that influenced the hydraulic conductivity of the sorbent and its suitability for continuous use. the appropriate isotherm model was utilized to determine the retardation factor in the advection-dispersion formula that clarifies the movement of cr along prb. for nonlinear regression calculations, the freundlich and langmuir isotherm models were utilized, and the parameter values obtained from these models are displayed in table 2. depending on the r2 and sse numbers, it was found that the langmuir model was more appropriate compared to the freundlich model. the langmuir constants have been determined to be 0.08 l/mg. the match between the experimental results and the sorption equilibrium models can be observed in fig. 3. the highest sudad adil salih al-khwarizmi engineering journal, vol. 19, no. 4, p.p. 1628 (2023) 21 adsorption capacity of mws for cr was found to be 23.57 mg/g. this finding indicates higher adsorption capacity due to cr bind with the msw more effectively. 20 (degree) fig. 2. x-ray diffraction (a) and ft-ir analysis pattern (b) for crystalline structure of ws, mws, cr, and sorbent after adsorption. 4.3 longitudinal dispersion coefficient in columns packed with a 1:15 proportion of sludge and sand, the aim of the present investigation was to explore the relationship between average pore velocity (v) and longitudinal dispersion coefficient (dl). to attain laminar flow conditions, flow rates were adjusted to 5, 10, 15, and 20 ml/min, ensuring that reynolds numbers (re) were maintained below 1-10. based on the data obtained from the experiment, as shown in fig. 3, it was observed that there exists a linear association between dl and v. 𝐷𝐿 = 13.953𝑉 + 0.046 … (15) 0 0.5 1 1.5 2 2.5 3 0 20 40 60 80 100 120 140 160 s o rb ed q u a n ti ty ( q t, m g /g ) ce (mg/l) (a) langmuir model freundlich model sudad adil salih al-khwarizmi engineering journal, vol. 19, no. 4, p.p. 1628 (2023) 22 fig. 3. the experimental results of mws and specifically the sand ratio (1:15), were compared with various isotherm models (a), and the longitudinal dispersion coefficient (b). the relationship between dl and v found in this study agrees with the relationship expressed in equation 16. in this equation, the the proportionality factor αl links dispersion and velocity in the longitudinal direction and has a dimension of length. this relationship is additionally influenced by the tortuosity (𝜏), which evaluates the impact of the water transition across a porous mediam which is influenced by the porosity of the medium (n). 𝜏 = 𝑛𝑚−1 … (16) the value of the parameter tortuosity (𝜏), that is affected by the material's porosity (n), is essential in explaining how the shape of the flow route influences the movement of water in a porous medium. eq. 16, where the constant value of m relies on the medium's aggregation phase, illustrates the connection between and n. in a laboratory experiment, archie (1942) found a value of 1.3 for unpacked sand, 1.8-2 for consolidated sandstone, and 1.3-2 for partly established sand. using the similarity between eq. 15 and eq. 16, the longitudinal dispersivity (αl) can be calculated for the prb medium (sludge:sand (1:15)). 4.4 column tests a permeable reactive barrier (prb) made of a sludge-sand (1:15) mixture was evaluated for its ability to remove cr contaminants from aqueous solutions while maintaining an acceptable hydraulic conductivity coefficient. the study utilized a column setup (fig. 1) and considered the rate of flow, concentration of chemical species, and bed depth. the study observed the normalized concentration (c/co) of the adopted contaminants with time at ports p1-p6 for a duration of up to 100 hours, as well as the variation in hydraulic conductivity coefficient (k) during the operation time. the advection-dispersion-sorption equation, which was numerically solved using the finite element method and the comsol program, was used to theoretically approximate the experimental breakthrough curves. table 2, isotherm model constants with statistical analysis for sorption cr. figure 4 depicts the outcomes of evaluating the normalized concentrations of cr at effluent ports p1 to p6 for up to 100 hours at a flow rate of 5 ml/min. y = 13.953x + 0.046 r² = 0.9898 0 0.2 0.4 0.6 0.8 1 1.2 0 0.02 0.04 0.06 0.08 d l ( c m 2 /s ) velocity (cm/sec) (b) adsorbent mws : sand (1:15) model parameter langmuir naxq 2.604 b 0.068 2r 0.976 sse 0.075 freundlich fk 0.456 n 2.810 2r 0.909 sse 0.298 sudad adil salih al-khwarizmi engineering journal, vol. 19, no. 4, p.p. 1628 (2023) 23 fig. 4. relationship between experimental findings and comsol results for the normalized concentration of cr under the influence of the initial concentration at various ports. the research discovered that the permeable reactive barrier (prb) impedes the spread of cr, and the concentration gradient has the potential to impact the saturation rate of the bed. the curve's shape is less prominent at lower influent concentrations due to sluggish sorption, while raising the influent concentration causes a steeper slope, leading to saturation of the sorbent in a shorter period. a low concentration gradient prolongs the propagation of chemical species through the pores, extending the time to reach saturation. the investigation revealed that the breakthrough time (tb) of 5% and saturation time (ts) of 90% rise with decreasing normalized concentration (c/co), affecting the adsorbed quantities of the contaminant at breakthrough and saturation points within the bed. with higher influent concentrations, the saturation of the adsorption process occurs more rapidly, leading to a decrease in breakthrough time. this phenomenon can be attributed to the presence of a larger concentration gradient, which intensifies the driving force for mass transfer of contaminant molecules. consequently, the adsorption sites become covered more quickly. additionally, the study observed that the adsorption capacity did not exhibit a proportional increase with rising influent concentration [43]–[45]. the purpose of the study was to examine how varying water flow rates affect the ability of a sorbent barrier to adsorb cr. by accounting for normalized concentrations at various points in the column using a variety of flow rates (5, 10, and 15 ml/min) and a fixed cr concentration of 10 mg/l, breakthrough curves were obtained. the findings demonstrated that with an increase in flow rate, the breakthrough time decreased and the curves exhibited a steeper slope. these observations suggested that the contaminated solution had not reached equilibrium within the column due to the reduced residence time caused by the higher flow rate. the faster flow rate also improved solute transport and increased sorption by creating a concentration gradient at the interface between the liquid and sorbent. however, the higher flow rate resulted in reduced solute adhesion to the sorbent and lower sorption efficiency, which could cause desorption of some adsorbed contaminant molecules, leading to an earlier breakthrough time. as a result, a lower flow rate was found to be more effective in adsorbing contaminants in the fixed bed due to its higher adsorption capacity. the study concluded that optimizing the water flow rate is critical for achieving maximum sorption efficiency in fixed bed adsorption systems [44], [46]–[48]. sudad adil salih al-khwarizmi engineering journal, vol. 19, no. 4, p.p. 1628 (2023) 24 fig. 5. relationship of experimental data and comsol results indicates a normalized concentration of cr with the impact of flow rate at various ports . in order to examine the impact of bed depth on sorption capacity, figures 4 and 5 were used. the findings demonstrated the same influent concentration and flow rate, adding more sorbent increased sorption capacity. the usual s-shaped breakthrough curves for cr adsorption indicate that as the bed depth increased the breakthrough time decreased and the effluent quantity increased. in continuous adsorption experiments, the sorbent reached an exhaust time at which it could no longer adsorb solute molecules, represented by a c/co of 0.9. the exhaust time was found to increase with increasing bed height, indicating that higher bed depths provided more active sites for adsorption. more time was provided for the adsorbate molecules to diffuse into the pores of the adsorbent particles, resulting in more contaminant molecules being adsorbed. as a result, the effluent volume increased with increasing exhaust time due to the higher bed depth. however, the adsorption capacity for contaminants decreased with increasing bed height due to two reasons: firstly, at higher bed heights, all binding sites become inaccessible to adsorbate molecules because of the overlap of active sites, resulting in some particles being inadequately utilized. secondly, lower bed depths were found to be more favorable for contaminant adsorption capacity, which is consistent with the findings of previous studies. therefore, it is crucial to use the entire capacity of an adsorbent for it to be effectively utilized in industrial applications [48]. 4.5 numerical modelling the study employed comsol multiphysics 3.5a (2008) software to solve the advectiondispersion equation. the software incorporates several modules, such as earth science, solute transport, saturated porous media, and transient analysis. simulation processes were established by inputting system dimensions and attributes, including boundary and initial conditions, as specified in table 3. one-dimensional measurements of column bed parameters and constants were used to characterize solute transport. the comparison between simulated results of contaminant transport and experimental measurements taken at different time intervals for a specific influent concentration and flow rate, revealed a high level of consistency. the coefficient of determination (r2) exceeded 0.97, indicating strong agreement between the model predictions and experimental data. table 3. adopted data used for simulating cr transport in columns. item parameter value aquifer characteristics aquifer bed depth (cm) 50 )anporosity of aquifer ( 0.38 longitudinal dispersivity ), cmlα( 13.953 )3bulk density (g/cm 1.677 initial condition initial concentration (mg/l) zero 5. conclusions this study aimed to investigate utilizing ws as a low-cost byproduct for water treatment procedures and decontaminating groundwater from cr. to achieve this goal, the ws sludge was modified using mgal-ldh-sand to create a permeable reactive barrier. the tests demonstrated successful remediation of the cr. langmuir modeling revealed that the modified sludge had exceptional sorption capacity, with a maximum adsorption capacity of 23.575mg/g. to accurately predict the behavior of different cr concentrations and bed depths, a mathematical model was utilized. the model was solved using the comsol software, and the accuracy of the results was confirmed with an r2 value greater than or equal to 0.97. these findings suggest that modified ws has the potential to be a cost-effective and efficient solution for treating groundwater contaminated with cr dye. sudad adil salih al-khwarizmi engineering journal, vol. 19, no. 4, p.p. 1628 (2023) 25 acknowledgements we would like to express our gratitude for the technical assistance and support provided by the chemical engineering department at the university of baghdad, iraq, during the course of this research. references [1] a. a. h. faisal, l. a. naji, a. a. chaudhary, and b. saleh, “removal of ammoniacal nitrogen from contaminated groundwater using waste 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(2023) 16-28، صفحة 2، العدد19مجلة الخوارزمي الهندسية المجلد سداد عادل صالح 28 تحقيق تنقية مياه الجوف الملوثة بمادة الكونغو الحمراء باستخدام حاجز مرشح نافذ بواسطة الحمأة المعدلة من محطات المياه سداد عادل صالح* طارق محمد نايف ** الهندسة / جامعة بغداد *،**قسم الهندسة الكيمياوية / كلية sudad.saleh1607m@coeng.uobaghdad.edu.iq*البريد االلكتروني: tariq.mohammed@coeng.uobaghdad.edu.iq**البريد االلكتروني: الخالصة ، وهي (cr) كمادة امتزازية إلزالة صبغة الكونغو الحمراء (ws) تهدف هذه الدراسة إلى استكشاف إمكانية استخدام الحمأة المستخدمة في محطات المياه ئي الطبقات بحجم مادة رخيصة تتولد كنتيجة فرعية لعمليات معالجة المياه. سيتم تحقيق ذلك من خالل ترسيب مركب هيدروكسيد المغنيسيوم واأللومنيوم الثنا أة المستخدمة في تقنية الحاجز المرشح نانو على سطح الحمأة. تم تأكيد كفاءة استخدام مركب هيدروكسيد المغنيسيوم واأللومنيوم الثنائي الطبقات لتعديل الحم . تم استخدام نموذج إيزوثيرما النجمير لتوضيح آليات االمتزاز المشاركة في العملية. باإلضافة إلى ذلك، تم xrdو ftir النافذ من خالل تحليلها باستخدام (r2) متنوعة. أشارت النتائج إلى ترابط قوي، مع معامل تحديدإلنشاء نموذج اختبار مستمر لتحليل نقل الملوثات تحت ظروف comsol استخدام نموذج مق السرير، وتزيد ، عند مقارنة توقعات النموذج بالقيم التجريبية، مما يشير إلى دقة النموذج. أظهر نقل المستمر نقاط اختراق أّولية سابقة عندما تقل ع0.97 ≤ . التركيز األولي ومعدل التدفق mailto:sudad.saleh1607m@coeng.uobaghdad.edu.iq mailto:tariq.mohammed@coeng.uobaghdad.edu.iq this is an open access article under the cc by license : al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 –1171, issn (online): 2312 –0789 vol. 21, no. 3, september, (2025), pp. 97105 supply chain resilience in the context of global production and logistics jaharah a. ghani1*, mohd fadzli abdollah2, muhammad rizal3, sulaiman elias4, aizat abdul rashid5, qamarul syahmi kamaruzaman6, nur ain najwa zainudin7, and muhammad nursyakirin hairil azmi8 1,4,5,6,7,8 department of mechanical and manufacturing engineering, faculty of engineering and built environment, universiti kebangsaan malaysia, 43600 bangi, selangor, malaysia 2 faculty of technology and mechanical engineering, universiti teknikal malaysia melaka, hang tuah jaya, 76100 durian tunggal, melaka, malaysia 3 department of mechanical and industrial engineering, faculty of engineering, universitas syiah kuala, 23111, darussalam, banda aceh, indonesia *corresponding author’s email: jaharahaghani@ukm.edu.my (received 24 june 2025; revised 23 july 2025; accepted 3 august 2025; published 1 september 2025) https://doi.org/10.22153/kej.2025.08.002 abstract this paper presents an in-depth review of supply chain resilience in the context of global production and logistics, considering the immediate need for adaptive and robust systems in the growing global scenario of uncertainties. this study aims to investigate the needs and strategy of scr for global production and logistics. first, 39 articles focusing on scr in the context of global production and logistics are selected. the articles are then classified according to the resilience strategy proposed by the authors. from the selected works published, the study unravels the key themes, such as definitions of resilience, disruption drivers, integration of digital technologies (e.g. digital twins) and the importance of cybersecurity. the paper further discusses the drawbacks of lean manufacturing, resilience metrics and its industrial applications during momentous events such as covid-19. the findings demonstrate that although applications of technology, such as ai and predictive analytics, have reinforced the resilience of production planning and control, many issues remain unaddressed in terms of the standardisation of metrics and coordinating sustainability with resilience. the paper presents recommendations endorsing hybrid resilience-efficiency models, cyber-resilience frameworks and multiindustry strategies to enable supply chains to face future disruptions. keywords: supply chain resilience; production planning and control; hybrid resilience-efficiency models; cyberresilience frameworks; multi-industry strategies. 1. introduction currently, unstable global conditions following the covid-19 pandemic and geopolitical uncertainties, such as the russia–ukraine conflict and the closure of the suez canal, have greatly affect the effectiveness of supply chains [1][2][3]. this instability has caused significant weaknesses in global production and logistics networks, highlighting the need for stronger and more resilient supply chains. in response, the concept of supply chain resilience (scr) was proposed, emphasising the capability of companies to operate efficiently by absorbing the uncertainties and maintaining customer confidence during crises [4][5]. accordingly, resilience in production planning and control (ppc) is essential to respond rapidly to unexpected changes in the supply chain. scr mailto:jaharahaghani@ukm.edu.my https://doi.org/10.22153/kej.2025.08.002 https://doi.org/10.22153/kej.2025.08.002 jaharah a.ghani al-khwarizmi engineering journal, vol. 21, no.3, pp. 97105 (2025) 98 includes the ability to anticipate, respond and bounce back from interruptions while controlling the manufacturing process [6][7]. these can be achieved by designing adaptable systems, as well as building backup and agile systems for immediate response to unexpected changes in demand or supply. pawar et al. [8] and ribeiro and barbosapóvoa [9] proposed resilience models and practices for quantifying the resilience of manufacturing systems. these approaches should be included for effective ppc interventions to avoid delays, stockouts and losses during periods of volatility. the integration of digital technologies has transformed the practice of applying resilience in modern supply chains. innovations such as machine learning, artificial intelligence (ai) and digital twins have helped realise data-driven capability for realtime decision-making and proactive management of disruptions [10][11][12]. these technologies enhance production control by leveraging the anticipation of probable risks, resource optimisation and adaptation of production plans based on changes [13][14]. as businesses shift towards industry 4.0, digital transformation becomes critical to enhance supply chain responsiveness and agility. increasing cyber threats and digital dependencies also justify the significance of cyberresilience in supply chain strategy. boyes [15] and khan and estay [16] asserted that protecting digital infrastructures is essential to ensure supply chain operations. production planning systems must be secured, especially when combined with external suppliers and global platforms. by the same token, firms are ever more concerned with harmonising resilience with sustainability objectives, motivating them to establish reactive and responsible supply chains [14][17]. lastly, establishing resilience in ppc must be undertaken holistically and prospectively by adopting advanced technologies, enhancing supply chain transparency, fostering cooperation and embedding risk management in operations, among other strategies [18][19]. big and small enterprises alike must redesign traditional planning approaches and invest in capacities to adapt and thrive during disruption. an understanding of the shifting dynamics of resilience will allow firms to conceive production systems that are better poised to meet future uncertainties. 2. methodology this study adopted a systematic search strategy to ensure a comprehensive review of the literature on scr in ppc, including keywords and criteria for inclusion and exclusion. the main aim was to provide as much information as possible to obtain a clear picture of the real situation regarding scr. for the purposes of this study, 39 articles were selected focusing on scr in the context of global production and logistics. this number was appropriate to give an early overview of scr. figure 1 shows the conceptual framework as explained by [20]. fig. 1. conceptual organisational resilience/ management control system framework [20] 2.1 search strategy information search was conducted in various databases, such as scopus, web of science, sciencedirect and google scholar. these databases were chosen due to their extensive coverage of peerreviewed articles and conference proceedings related to operations management, logistics and industrial engineering. boolean operators were used to identify and combine specific keywords and search terms, such as ‘supply chain resilience’, ‘resilient supply chain’, ‘production planning’, ‘production control’, ‘resilience strategies in manufacturing’ and ‘disruption management in supply chains’. only relevant articles were selected for the study. 2.2 classification of articles the articles were classified according to the research methodology and resilience strategy proposed. this classification provided a clear structure for identifying key themes, understanding the current state of research and recognising gaps or underexplored areas in the literature. jaharah a.ghani al-khwarizmi engineering journal, vol. 21, no.3, pp. 97105 (2025) 99 3. analysis and discussion the analysis was based on 39 selected articles from the literature on scr in the context of ppc. key themes that emerged include definitions and conceptual frameworks, causes of disruptions, the integration of resilience into planning systems, resilience measures, applications in industry, and gaps in existing knowledge. 3.1 definitions of supply chain resilience in today’s fluctuating and risky business environment, organisations are increasingly faced with disruptive events, such as pandemics, natural catastrophes, cyber-attacks and geopolitical tensions [19]. these disruptions pose serious challenges for global supply chains, making resilience an issue of extreme priority. based on the literature, many authors define scr as the ability of a system to anticipate, absorb, adapt to and recover from disruptive events [8]. this general definition concludes that foresight, robustness, flexibility and recovery are the essential qualities organisations must cultivate in their supply chains to ensure continuity and competitiveness. simply put, scr is the strategy of planning ahead for unexpected problems through prior design and planning of the supply chain [21]. it is the capacity to adapt quickly to disruptions and retain control over operations. a resilient supply chain not only recovers but comes out even stronger after a disruption, making the business more competitive than others. 3.2. drivers of supply chain disruptions supply chain disruptions are driven by several key factors. global transportation bottlenecks, particularly in maritime shipping, have a significant impact, as 80% of international trade depends on sea transport [22]. one of the best-known disruptions is the ever given case, a gigantic container ship that ran aground and blocked the suez canal in march 2021 for six days. this event highlighted the manner in which a single disruption at a chokepoint can lead to extensive ripple effects throughout global supply chains, resulting in delayed deliveries and total losses amounting to usd 88.79 million [2]. commodity price shocks caused by abrupt increases in the prices of crude oil, natural gas, coal, fertilisers and metals are also major contributors [23]. an example of geopolitical events like russia’s invasion of ukraine add to these disruptions by increasing the prices of energy and essential goods and causing logistics bottlenecks, especially for countries that rely on russian energy [1]. moreover, the covid-19 pandemic intensified existing supply chain vulnerabilities and created new challenges, particularly through widespread lockdowns and labour shortages. these were especially severe in critical areas in the global logistics network [18]. consequently, backlogs occurred due to ships waiting longer to dock and unload. these effects spread throughout the supply chain, resulting in inventory shortages, increased shipping costs and interrupted production in various industries. 3.3 cybersecurity in supply chain robust cybersecurity measures are necessary due to the increasing cyber threats arising from the digitisation of supply chains [16]. the complex interdependencies in supply chains make them vulnerable to common threats, such as ransomware, phishing and insider attacks. these threats can expose sensitive information and disrupt operations [24]. to overcome these problems, comprehensive cybersecurity frameworks, enhanced interorganisational cooperation and real-time threat detection systems must be implemented [24]. global sourcing, diverse legal jurisdictions and reliance on third-party services have further complicated the realisation of supply chain cyberresilience [15]. protecting against cyber-physical system attacks requires the integration of cyber and physical security as a holistic approach for cybersecurity. according to ibiyemi and olutimehin [24], effectively safeguarding supply chains in the digital age necessitates preventive measures, detection and response strategies and recovery planning. achieving these goals requires policy and regulatory compliance. cyber threats are seen as critical and increasingly damaging sources of disruption in supply chain risks. cyber attacks have caused disruptions in supply chain operations across industries in several high-profile cases. among them was the notpetya malware attack in 2017, which caused over usd 10 billion loss in a single cyber event [24]. another case was the 2020 solarwinds orion breach, which involved a supply chain attack on thousands of organisations, including several u.s. government agencies. the most recent event was the ransomware attack on jbs sa in 2021, which resulted in operational shutdowns across north america and australia, jaharah a.ghani al-khwarizmi engineering journal, vol. 21, no.3, pp. 97105 (2025) 100 highlighting the ability of cyber threats to cause immediate production halts and supply delays. these cases show the urgent need to incorporate cybersecurity risk assessment for creating scr. 3.4 complex interdependencies the significant impact of covid-19 on global supply chains signalled the need for their resilience and flexibility [3]. complex associations in modern supply chains have caused fatal effects during disruptions in various sectors [25], including transportation disruptions, manufacturing slowdowns, supply-demand imbalances and operational inefficiencies [26]. scr can be enhanced by focusing on digital-intensive business models, collaborative network designs and sustainability [26]. the risks can be mitigated by employing strategies such as redundancy, flexibility and localisation [3]. effective decision-making must be able to capture complex interdependencies between supply chain disruptions, mitigation strategies and firm performance [27]. the dependencies and vulnerabilities of the global supply chain can be assessed using network analysis tools [25]. in general, developing more resilient and adaptable supply chains in the future is crucial to overcome unexpected situations such as the covid-19 pandemic. 3.4.1 cross-sector supply chain integration during crisis the covid-19 pandemic not only stressed individual supply chains but also catalysed unprecedented cross-sector collaborations, exemplifying how industries can dynamically reconfigure under extreme pressure. a notable case is the intertwining of the automotive and medical device supply networks to rapidly scale the production of ventilators, a critical medical resource during the height of the crisis. automotive manufacturers, equipped with robust production systems, advanced logistics networks and precision engineering capabilities, collaborated with medical device firms to meet the surging demand. this emergent partnership showcases the adaptive capacity of supply chains to transcend sectoral boundaries when confronted with urgent societal needs [7]. this case also exemplifies the concept of complex interdependencies, where agility and openness to cross-industry integration became essential features of resilience. rather than being confined to traditional roles, supply chains displayed fluidity—repurposing tooling lines, reallocating resources and merging knowledge systems in real-time. it also highlights the importance of modular design, interoperable systems and multi-use capabilities in future supply chain planning. for ppc, this case emphasises the need for flexible planning frameworks that allow organisations to shift focus, reprioritise outputs and collaborate across industry boundaries without compromising efficiency or compliance [7]. 3.4.2 corporate case studies a study that examined corporate case studies revealed that the leading firms enhanced their scr through flexibility, rapid response and proactive planning. rice and sheffi [28] examined how giant companies such as land rover, aisin seiki co., united parcel service (ups), dell, baxter international, dhl and nokia embedded agility into their supply chain operations in order to understand how they adapted to supply chain disruptions. the stated companies faced various disruptions, including natural disasters, supplier problems and geopolitical risks, but successfully overcame those through structural and strategic flexibility. the success was achieved through preemptive investments in supply chain agility. for example, dell leveraged built-to-order models and real-time information, and dhl and ups capitalised on network redundancy and visibility tools to reroute operations during crises. these examples collectively show that resilience is not merely a reactive capability but a designed-in feature enabled by flexible procurement contracts, diversified supplier bases, it infrastructure and empowered response teams. the ability to detect, interpret and act on disruption signals early—while maintaining service levels—positions such companies to not only recover but also to gain a competitive advantage in turbulent environments [28]. 3.5 lean manufacturing limitations recent research highlights the limitations of lean manufacturing and just-in-time inventory systems in the face of disruptions. while these practices enhance efficiency under normal conditions, they can exacerbate the impact of disruptions due to minimal buffer stocks and reliance on precise timing [4][29]. the covid-19 pandemic exposed the lack of resilience in supply chains, prompting a reevaluation of these practices [30]. more resilient approaches are needed that balance efficiency with risk mitigation. solutions proposed include jaharah a.ghani al-khwarizmi engineering journal, vol. 21, no.3, pp. 97105 (2025) 101 integrating resilience principles into lean manufacturing systems, implementing the scram framework to assess and manage supply chain vulnerabilities [4] and adopting a dynamic mix of lean and legacy supply chain practices through coordinated demand-driven production [31]. these solutions aim to create flexible and resilient production systems that can respond effectively to disruptions while maintaining efficiency. 3.6 resilience in production planning and control the integration of advanced technologies to strengthen scr and production planning was highlighted recently. in complex manufacturing environments, digital twins, which leverage machine learning and real-time data, are key elements that enable proactive risk management and adaptive decision-making [10][13]. these technologies facilitate end-to-end visibility, allowing organisations to anticipate and respond to disruptions effectively [10]. demand forecasting and risk assessment capabilities across the supply chain are improved by utilising predictive analytics and data-driven strategies, incorporating iot and cloud computing [32]. machine learning algorithms can be combined with production system data to implement intelligent digital twins for adaptive ppc [11]. these approaches offer significant potential for enhancing scr and operational efficiency due to increasing market volatility and disruptions. recent research on scr metrics emphasises the importance of resilience by evaluating its strategies. hosseini et al. [33] proposed a bayesian network approach that balances vulnerability and recoverability to measure scr. meanwhile, a new resilience measure based on the ratio of system performance after disruption to normal state performance was introduced by li et al. [34]. ribeiro & barbosa-póvoa [9] developed a responsiveness metric incorporating economic and customer impact objectives for resilient supply chain design and planning. additionally, existing scr metrics were reviewed by behzadi et al. [6], who proposed a new measure called the net present value of the loss of profit (npv-lp). table 1 shows the comparative table of scr metrics. table 1. comparative table of scr metrics metric approach focus strengths limitations best use case bayesian network [29] probabilistic graphical model vulnerability and recoverability handles uncertainty, models complex interdependencies high data/expert input demand strategic risk analysis, scenario planning performance ratio [30] ratio-based performance measure post-disruption performance vs. normal simple, intuitive, fast to apply ignores long-term effects, oversimplifies dynamics quick diagnostics, comparative benchmarking responsivene ss metric [9] multi-objective optimisation economic + customer impact holistic, aligned with planning goals computationally intensive design and policy optimisation npv-lp [6] economic loss quantification financial impact (profit loss) financial rigor, supports roi evaluation data-intensive, excludes qualitative factors investment justification, costbenefit analysis these studies help to identify the need for comprehensive metrics that consider multiple factors, including recovery time, system performance, economic impact and customer responsiveness. this enables for better effective decision-making in supply chain management and enhances overall resilience to disruptions. 3.7 applications in industry the importance of ai in enhancing scr across industries continues to grow, as highlighted by recent research. in manufacturing, ai applications contribute significantly to predictive maintenance, risk mitigation and quality control, with machine learning and deep learning being the predominant technologies [12]. the healthcare sector has leveraged ai, blockchain and big data analytics to manage disruptions during the covid-19 pandemic, although practical applications remain limited [35]. ai’s potential to improve scr is further emphasised through early risk identification, operation optimisation and enhanced decisionmaking [36]. in the usa, companies are jaharah a.ghani al-khwarizmi engineering journal, vol. 21, no.3, pp. 97105 (2025) 102 increasingly adopting technologies such as ai, blockchain and iot to predict disruptions, optimise operations and respond swiftly to challenges, demonstrating the critical role of continuous innovation in maintaining operational continuity [37]. 3.8 gaps in existing knowledge recent research highlights significant gaps in scr and sustainability. standardised metrics for measuring resilience are lacking, making benchmarking challenging across industries [5][17]. in addition, the relationship between sustainability and resilience remains unclear, with conflicting perspectives on whether they are separate concepts, components of each other or synonymous [14]. this ambiguity extends to implementation methods and performance measurements [17]. exploring how emerging technologies impact scr is necessary as well. research streams have developed divergent definitions and theories of resilience, limiting the potential for generalisable principles [5]. future research should focus on integrating existing knowledge, developing standardised frameworks and investigating the intersection of sustainability and resilience strategies to address these gaps [14][17]. 3.8.1 future recommendations integration of digital twins and predictive analytics future research should explore how digital twins, enhanced by machine learning and real-time analytics, can be systematically embedded into ppc systems to simulate disruption scenarios and design proactive response strategies [10]. these tools can improve visibility, reduce lead times and support decision-making during uncertainty. hybrid resilience-efficiency models there is an urgent need to develop hybrid models that integrate resilience with the efficiency of lean systems. this approach may include the incorporation of selective redundancies, dynamic safety stocks and risk-based segmentation in inventory and supplier strategies. cyber-resilience frameworks in ppc with digital transformation accelerating, future research should prioritise cybersecurity in ppc environments. interdisciplinary studies can bridge the gap between supply chain operations and information security, contributing to more secure and resilient digital ecosystems [38]. cross-sector resilience strategies real-world case studies from the covid-19 pandemic illustrate the potential of cross-sector collaboration in enhancing agility and modular adaptability. investigating frameworks for interindustry cooperation, such as shared production capacities and interchangeable components, can support systemic resilience [10]. resilience metrics and decision-support tools the development of standardised resilience metrics and decision-support dashboards, which include real-time monitoring and scenario modeling, can significantly enhance risk visibility and responsiveness across production systems [35]. policy and governance implications scholars should examine the impact of policy, trade regulation and public-private partnerships in supporting resilience investments. effective institutional governance can create incentives for firms to adopt long-term resilience strategies [39]. 4. conclusions this systematic review underscores the growing need for embedding resilience within supply chain management, particularly in ppc. as global supply chains face increasingly frequent and severe disruptions, ranging from natural disasters and pandemics to cyber-attacks and geopolitical conflicts, resilience has become a strategic imperative rather than a supplementary feature. the literature reveals several recurring themes: the foundational constructs of scr, sources and types of disruption, the integration of digital technologies such as digital twins, growing cybersecurity vulnerabilities and the inherent limitations of traditional lean paradigms in turbulent environments. while lean systems 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[39] m. christopher and h. peck, "building the resilient supply chain," the international journal of logistics management, vol. 15, no. 2, pp. 1–14, 2004. doi.org/10.1108/09574090410700275 ( 2025) 97-105، صفحة 3، العدد21مجلة الخوارزمي الهندسية المجلد عبد الغني اجهار 105 مرونة سالسل التوريد في سياق اإلنتاج والخدمات اللوجستية العالمية jaharah a. ghani1*, mohd fadzli abdollah2, muhammad rizal3, sulaiman elias4, aizat abdul rashid5, qamarul syahmi kamaruzaman6, nur ain najwa zainudin7, muhammad nursyakirin hairil azmi8 1,4,5,6,7,8department of mechanical and manufacturing engineering, faculty of engineering and built environment, universiti kebangsaan malaysia, 43600 bangi, selangor, malaysia 2faculty of technology and mechanical engineering, universiti teknikal malaysia melaka, hang tuah jaya, 76100 durian tunggal, melaka, malaysia 3department of mechanical and industrial engineering, faculty of engineering, universitas syiah kuala, 23111, darussalam, banda aceh, indonesia jaharahaghani@ukm.edu.myالبريد االلكتروني: * المستخلص ( في سياق اإلنتاج والخدمات اللوجستية العالمية، مع مراعاة الحاجة الملحة ألنظمة scrمرونة سلسلة التوريد ) وضوعلم عميقةمراجعة البحث اهذ يقدم التوريد في اإلنتاج والخدمات اللوجسبتية سبسسبلمرونة اتإلى دراسبة احتياجات واسبتراتي ي البحث يهدفالعالمية. الضبباييةمتكيفة وقوية في ظل تنامي حالة نفت مرونة سببس " تناولتيحثا 39العالمية. تم اختيار وفقاً السببتراتي ية المرونة التي البحوثسببل التوريد في سببياق اإلنتاج والخدمات اللوجسببتية العالمية. بب الضبو على مواضبيع رسيسبية مثل تعريفات المرونة، ومحر ات االضب،راد، ودمت التقنيات تم تسبلي اقترحها المؤلفون. من يين األعمال المختارة المنشبورة، عيود التصببنيع الرقببيم، ومقاييم المرونة، وت،بيقاتص الصببناعية خسل ناقش البحثثل التواسم الرقمية، واألهمية القصببول لنمن السببيبراني. ما الرقمية م النتاست أنص على الرغم من أن ت،بيقات التكنولوجيا، مثل الذ ا اال ببب،ناعي والتحليست التنبؤية، قد ع ت اظهرت. 19-الكبرل مثل جاسحة وفيد الكوارث معال ة فيما يتعلم يتوحيد المقاييم وتنسببيم االسببتدامة مع المرونة. يحاجة الى(، إال أن العديد من القضببايا ال ت ال ppcمرونة تخ،ي اإلنتاج والتحكم فيص ) يما ي تيح لسببسسببل المتعددة، الصببناعات ي يات يعض التو ببيات التي تدعم نما ج المرونة والكفا ة اله ينة، وأ ر المرونة السببيبرانية، واسببترات قدم البحث التوريد مواجهة االض،رايات المستقبلية. mailto:jaharahaghani@ukm.edu.my <4d6963726f736f667420576f7264202d20c7d3d1c7c120e6cf20c7d3c7e3c920c3cde3cf20cdc8c7d320312d3130> al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 16, no. 4, december, (2020) p. p. 1-10 applying trade-off curve to support set-based design application in aerospace company esraa m. mohsin* osamah f. abdulateef** ahmed al-ashaab*** *,** department of automated manufacturing engineering/ al-khwairzmi college of engineering/ university of baghdad/ iraq *** department of manufacturing / school of applied sciences/ cranfield university)/ uk *email: asowyasowy@yahoo.com **email: drosamah@kecbu.uobaghdad.edu.iq ***email: a.al-ashaab@cranfield.ac.uk (received 7 september 2020; accepted 25 october 2020) https://doi.org/10.22153/kej.2020.10.001 abstract companies compete greatly with each other today, so they need to focus on innovation to develop their products and make them competitive. lean product development is the ideal way to develop product, foster innovation, maximize value, and reduce time. set-based concurrent engineering (sbce) is an approved lean product improvement mechanism that builds on the creation of number of alternative designs at the subsystem level. these designs are simultaneously improved and tested. the weaker choices are removed gradually until the optimum solution is finally reached. sbce implementations have been extensively performed in the automotive industry and there are a few cases studies in the aerospace industry. this research describes the use of trade-off curve as a lean tool to support sbce process model in configuration optimization of next generation aircraft project (conga), using nasa simulation software version 1.7c and conga demonstration program (demo program). this method will help designers and engineers to extract the design solution according to the customer requirement to achieve low noise engine at an aerospace company, and also extract the infeasible region where the designers cannot make any prototype in this region before manufacturing process begin, that will lead to reducing rework, time and cost. keywords: knowledge management, lean product development, sbce, trade-off curve. 1. introduction the lean knowledge management is known as an important condition that enables companies to obtain the right knowledge of the right people with form and quality at the right time. significant enhancement of decision taking in product development is achieved when it is based on proven knowledge. this is achieved by creating a knowledge-based framework and knowledge visualization via the use of trade-off curves. trade-off curves will allow designer engineering to compromise alternative solutions due to conflicting attributes in any aspect of the product lifetime [1]. simply, the trade-off curve (toc) is a tool to understand the relationship of various design characteristics to each other. they usually describe the link between at least two key factors that relate design decision(s) to parameter(s) that clients concern about over a set of values. ward et al. [2] presented “set-based concurrent engineering”, a procedure that demands various design solutions in comparison to conventional point-based product creation, to explain how esraa m. mohsin al-khwarizmi engineering journal, vol. 16, no. 4, p.p. 110 (2020) 2 japanese companies gain an advantage by relying on adequate information to postpone design decisions; the point-based approach restricts design space and offers less versatility in adapting design solutions among the different functions of product development. in comparison, a set-based approach allows product improvement functions to investigate design space and converge during the system narrowing process into an optimal design solution. to describe the knowledge environment, the researchers grouped methods and techniques in lean product creation into three main groups: decision-making, knowledge provision, and knowledge visualization. previous research work identified “trade-off curves” in various ways that are at some points identical to one another. for example, sobek et al. [4] defined a “trade-off curve” as a relationship between two or more factors. according to kennedy et al. [5], a “trade-off curve” is a relationship between two or more design decisions and is the knowledge of the subsystem from which design options are evaluated and narrowed until the optimal design is selected, thereby providing reusable information for future product design. simply, it can be said that the trade-off curve is a tool to understand the relationship of various design characteristics to each other. trade-off curves have a two-dimensional (2d) form and a multidimensional form. ward et al. [2], interviewed with toyota's supplier, pointed the importance of trade-off curves. the teamwork of toyota company tried to reduce the noise with the muffler. to reduce noise, they created back pressure in the exhaust and the gas flows out of the engine. therefore, there was a trade-off between reducing the noise and creating the backpressure, and the backpressure reduces the performance of the engine. haselbach and parker [6], used a multidimensional trade-off curve to describe key technologies within aircraft engine combustion and core turbine systems contributing to low emissions products, fuel-efficient in the large civil aircraft engine market. araci et al. [7], created a knowledge environment using trade-off curves during the early stages of the set-based concurrent engineering (sbce) process of an aircraft jet engine for a reduced noise level at takeoff. data was collected from a range of products in the same family as the jet engine. knowledge-based trade-off curves are used as a methodology to create and visualize knowledge from the collected data. findings showed that their method provides designers with enough confidence to identify a set of design solutions during the sbce applications. maksimovic [8], used a trade-off curve to capture the information when designing the structures of car seat. the capture of trade-off information involves the required sheet metal selection during the design of the structures of car seat, based on the criteria defined for the decision. araci and alashaab [9], developed a systematic process for set-based concurrent engineering to develop a new product. they noticed that tocs based on physics could help to define different product physics characteristics in the form of design parameters and visualize in a single graph for all stakeholders to understand without the need for a comprehensive background in engineering. araci et al. [10], demonstrated the integrated use of tocs in the sbce process model in an industrial case study for a surface jet pump. the evaluation of a set of 60 different design solutions using a conventional approach could potentially be very resource-intensive; the application of knowledgebased and physics-based tocs allowed the design-set to be progressively reduced until the optimal design solution was found. as a result of the literature review, a research gap has been defined that "there is no clear framework and sequence of stages that will assist the creation and visualization of a knowledge environment to support set-based concurrent engineering applications". this research aims to construct a systematic approach for knowledge provision and visualization to support decision making in the early stages of “set-based concurrent” engineering applications via the use of “trade-off-curves (toc)” during concept design of low noise engine identified decision criteria by designers and engineers. trade-off curves will be based on these decision criteria (engine thrust force, bypass ratio, thrust specific fuel consumption (tsfc) and engine noise level), which is part of conga (configuration optimization of next generation aircraft) project collaborated with aerospace company supported by technology strategy board (tsb). the conga consortium has 6 industrial partners: airbus, airbus group innovations, aircraft research association, eurostep, msc software, and rolls-royce including cranfield university. conga project aims to develop new multidisciplinary design and integration processes to support the conceptual design and assessment of future aircraft configurations. such developments are essential if designers are to be able to deliver robust product concepts (at the early stages of the design cycle) for novel aircraft and power plant configurations that embed new technologies. esraa m. mohsin al-khwarizmi engineering journal, vol. 16, no. 4, p.p. 110 (2020) 3 2. the sbce process model the sbce process model developed by khan et al. [3] composed of principles which can be applied at the early phase of a development process [5], it consists of several key phases. each phase is divided into activities, as shown in table (1). table 1, the fundamental conga sbd process model. 1. define value 2. map design space 3. develop concept set 4. converge on system 5. detailed design 1.1 classify projects 2.1 identify subsystem targets 3.1 extract (pull) design concepts 4.1 determine intersections of sets 5.1 release final specification 1.2 explore customer value 2.2 decide on level of innovation to sub-systems 3.2 create sets for sub-systems 4.2 explore possible product system designs 5.2 manufacturing provides tolerances 1.3 align project with company strategy 2.3 define feasible regions of design space 3.3 explore subsystem sets: simulate, prototype, and test 4.3 seek conceptual robustness 5.3 full system definition 1.4 translate value to designers (via product definition) 3.4 capture knowledge and evaluate 4.4 evaluate possible systems for lean production 3.5 communicate sets to others 4.5 design process planning for manufacturing 4.6 converge on final system this study will explore the activities that tradeoff curves can enable to support sbce in the aerospace company as follows: a. choose the activity (2.3): define a feasible region of design space. b. choose the activity (3.4): capture knowledge and evaluate. c. choose the activity (3.5): communicate sets to others. d. choose the activity (4.2): explore possible product system designs. there are many steps to construct toc as shown in figure (1) to achieve low noise engine in conga project esraa m. mohsin al-khwarizmi engineering journal, vol. 16, no. 4, p.p. 110 (2020) 4 fig. 1. the process of constricting toc. 3. defining decision criteria/ key attributes capturing of trade-off knowledge during concept design of low noise engine identified a decision criterion by designers and engineers. “trade-off curves” will be based on certain parameters for decision (engine thrust force, bypass ratio, tsfc, and engine noise level). value of the four decision criteria were discussed with the designers and engineers at an aerospace company and they decided: a. engine thrust force is supposed to be high. b. the bypass ratio must be high. c. the engine noise level must be low. d. tsfc is supposed to be low. 4. getting the data related to each of the key attributes from the aerospace company data was compiled from the aerospace company for different types of real turbofan civil engines [11]; then data was extracted and eight different types of engines were selected depending on the highest maximum take-off mass (mtom) for each type. further data will then be collected from engineering calculation to compute the engine noise level for each type of real engine as shown in tables (2) and (3). the engine noise level was calculated as follows: the process of constructing toc define decision criteria/ key attribute get the data related to each of the key attribute real data from aerospace company data from nasa simulation software data from engineering calculation for engine noise level data from conga demonstration program for engine noise level generate different trade-off curves get the requirement (customer) and plot these requirements against convert these potential solutions to useful solution develop set of potential solution that could be useful for project under define feasible/ infeasible/ comfort extract/ locate the design solution (where is it physically) esraa m. mohsin al-khwarizmi engineering journal, vol. 16, no. 4, p.p. 110 (2020) 5 a. take-off noise (to): 100% of the noise is engine noise. b. approach noise (appr): 50% of the noise is engine noise and 50% is airframe noise. c. flyover noise (fo): 75% of the noise is engine noise and 25% is airframe noise. d. cumulative noise: 100% to + 50% appr + 75% fo = engine cumulative noise. table 2, data from an aerospace company certified by icao [11]. id type version engine take-off noise (epndb) flyover noise (epndb) approach noise (epndb) cumulative noise (epndb) airbus_18615 a340 541 trent 55361 95.4 96.4 99.5 291.3 airbus_18634 a340 642 trent 55661 95.8 95.9 100 291.7 airbus_18642 a340 643 trent 56061 96.8 94.2 100 291 airbus_18881 a330 341 trent 76860 96.9 89.6 96.9 283.4 airbus_18817 a330 243 trent 77260 97.4 91.3 96.9 285.6 airbus_20919 a380 841 trent 970 94.2 95.9 98 288.1 airbus_20928 a380 842 trent 972 94.6 94.5 98 287.1 airbus_20927 a380 842 trent 972 94.5 95.1 98 287.6 table 3, engine noise level of the real engine from engineering calculations [11]. id type version engine take-off noise (epndb) flyover noise (epndb) approach noise (epndb) cumulative noise (epndb) airbus_18615 a340 541 trent 55361 95.4 72.3 49.75 217.45 airbus_18634 a340 642 trent 55661 95.8 71.925 50 217.725 airbus_18642 a340 643 trent 56061 96.8 70.65 50 217.45 airbus_18881 a330 341 trent 76860 96.9 67.2 48.45 212.55 airbus_18817 a330 243 trent 77260 97.4 68.475 48.45 214.325 airbus_20919 a380 841 trent 970 94.2 71.925 49 215.125 airbus_20928 a380 842 trent 972 94.6 70.875 49 214.475 airbus_20927 a380 842 trent 972 94.5 71.325 49 214.825 the conga case-study requirements or (customer requirement) are as follows: a. fan diameters between (2 – 2.5) m. b. tsfc: 0.055 kg/s. c. low noise aircraft. d. engine cumulative noise limit for eu airports: 212 epndb. e. engine thrust force variants (315– 320) kn. toc was drawn on three-axis by using matlab 8.4 software, the three-axis are decision criteria, the x-axis spouse to be engine thrust force, the y-axis spouse to be either engine cumulative noise level or tsfc and the z-axis spouse to be bypass ratio. by projecting the customer requirements against tocs then the design required extracted physically in a faster and easier way and also other real engines that meet the customer requirement can be extracted to generate a set of possible solutions. 5. results and discussion tradeoff curve used to generate a set of solutions and also use during set narrowing as follows: esraa m. mohsin al-khwarizmi engineering journal, vol. 16, no. 4, p.p. 110 (2020) 6 a. mapping initial needs of customers versus the created trade-off curves give a collection of information that will create a set of design solutions. such information is focused on the decision criteria that could relate to manufacturing process ability, test efficiency, material, and cost as captured in the trade-off curves shown in figure (2). the optimum solution for the decision criteria bypasses ratio and engine thrust force from trade-off curve one is trent 772-60, which is meet the minimum customer requirements for bypass ratio and has high engine thrust force and good in engine cumulative noise level, but not good in tsfc, as shown in figure (3). fig. 2. trade-off curve one between bypass ratio and engine thrust force with a real engine. fig. 3. trent 772-60 optimum solution according to bypass ratio and engine thrust force. b. the second trade-off curve is between the decision criteria engine thrust force and engine cumulative noise level; the optimum solution from this curve is trent 768-60 as shown in figure (4). trent 768-60 has a higher bypass ratio and better tsfc than trent 772-60, but not good in decision criteria of engine thrust force, and it is well for engine cumulative noise level, as shown in figure (5). fig. 4. trade-0ff curve tow between engine thrust force and cumulative noise level with a real engine. 224 244 264 284 304 324 0 2 4 6 8 10 t h ru st f o rc e ( k n ) bypass ratio bypass-thrust real engine trent 772-60 esraa m. mohsin al-khwarizmi engineering journal, vol. 16, no. 4, p.p. 110 (2020) 7 fig. 5. trent 768-60 optimum solution according to engine thrust force and engine cumulative noise level. c. the third trade-off curve is between fan diameter and engine cumulative noise level; the optimum solution from this curve is trent 560-61, as shown in figure (6). trent 560-61 has a high bypass ratio, but not good for other decision criteria when compared to trent 77260 and trent 768-60, as identified in figure (7). fig. 6. trade-off curve three between fan diameter and engine cumulative noise level with real engines. fig. 7. trent 560-61 optimum solution according to fan diameter. d. the fourth trade-off curve is between decision criteria engine thrust force and tsfc; the optimum solution for these criteria is trent972, as identified in figure (8). trent 972 has high bypass ratio and meet the customer requirement for tsfc and engine cumulative noise level; trent 972 is not well in engine thrust force as like as trent 772-60, but better than trent 768204 208 212 216 220 224 1.4 1.7 2 2.3 2.6 2.9 3.2 3.5 3.8 4.1 4.4 4.7 cu m m u la ti v e n o is e l e v le ( e p n d b ) fan diameter (m) real engine fan diameter-cummulative noise trent 560-61 esraa m. mohsin al-khwarizmi engineering journal, vol. 16, no. 4, p.p. 110 (2020) 8 60 and trent 560-61. figure (9) illustrates trent 972 according to the four decision criteria. fig. 8. trade-off curve four between engine thrust force and tsfc with real engines. fig. 9. trent 972 optimum solution according to engine thrust force and tsfc. the process for initiating a collection of resulting design solutions is the unavoidable conflict between different trade-off curves to provide the best suited design solution among certain trade-off variables as identity in figure (10). fig. 10: mechanism of narrowing set base design. 0.04 0.045 0.05 0.055 0.06 0.065 0.07 0.075 0.08 224 244 264 284 304 324 t s f c ( k g /k n .s ) thrust force(kn) real engine thrust-tsfc trent 972 esraa m. mohsin al-khwarizmi engineering journal, vol. 16, no. 4, p.p. 110 (2020) 9 throughout the face to face conversations, designers and engineers in aerospace company summarized four criteria for deciding according to the importance (bypass ratio, engine thrust force, tsfc, and engine cumulative noise level), depending on the importance of decision criteria, set of solution narrowed down from four solutions to two solutions (trent 772-60 and trent 972), by compromising engine thrust force. the optimum design solution was trent 972 that meet the customer requirements. 6. conclusions to create better designs, it is critical to develop a methodology to discover, retain, organize, and present knowledge throughout all phases of the aircraft life-cycle. this methodology must consider knowledge management in the aircraft design, production, and operations to be flexible enough to capture the inherent variability of the system. the significant enhancement of decision taking in lean product and process development (leanppd) is achieved when it is based on lean thinking and implemented toc as a source of knowledge to support value creation to the customers. the trade-off curves work so well because they combine the power of mathematics with the power of human visual processing system and can be visually displayed multidimensional in a single graph, that is mean we can generate toc in 2d or 3d or multidimensional depending on the decision criteria, while visual cortex has a big part in the brain, mathematics has a small part, so by taking mathematics and putting it in the form of visual curves we can understand it faster. the trade-off curve support sbce process model by choosing some activities from this model, as generated set of solution to meet the customer requirement and then narrow down the set of solution to meet the customer requirement and then narrow down the set of the solution by depending on decision criteria until reach to the optimum solution. 7. references [1] t. a. roemer and r. ahmadi, “concurrent crashing and overlapping in product development,” operations research, vol. 52, no. 4, pp. 606-622, 2004. 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[11] https://www.icao.int/safety/istars/pages/apidata-service-new.aspx. ��� 4، ا���د��16 � ا���ارز�� ا������� ا��� � أ� اء ���� ����� ،10 -1 )2020( 10 ات� ! � �" 0!/�. ����ا��, +*� ��(' ����(� ا�&) ��' ا������� ا��&%ا��� $� # أ��8 8/ س ا6#�5*** أ� �� $ 34 (/�ا� !�2** أ� اء ���� ����* ���اد��� ھ���� ا ����� ا �����/ ��� ا ����� *،** ���� /!� ا %$ارز +ا*(���/ ا ���)� ا ��'�ة ��� ***��� ا �����/ � asowyasowy@yahoo.com:ا /+.� ا)�+و*! * drosamah@kecbu.uobaghdad.edu.iq** ا /+.� ا)�+و*!: ashaab@cranfield.ac.uk-a.al :ا /+.� ا)�+و*! *** �� ا��9 8! �5$.+ ا ���4�ت ا ���%���.و�= ا 5+ق ا �� ��� ا>�$اق:�9 ا ��5+ة����78 ا 6+ �ت �+ض �$5.+ ���4���� وا��)�ر ���4�ت �.�ه �+ض ��?��= ا @ � a�b+� ھ$ ا��%�ام 8)+ه ا���d ا e%��� .��$ ا @��d()+ة و� ا ������$ى ا �?�م ا (+:! و.�� ا /�.��8! :�@ *5�ق وا�� �= ا ��� 9�: ��$ره ���')�����hوا��/��د ا %��رات ��gاi<ل ا$k$ 9 ا�l !4.6)@ ��ر� /�+ �k !8�p: ا /5� �� .�d.+5�a ھoه ا �n� ��ا '�$ل إ 9 @(6� �qا p���� ���( رات و��� ت ا�:��� ى�%�ام 8! ا+r<ات. ا+s�5 ا p:��k ���� و !�'�� t'/ ا اoم ھ�d.��i�)� ا ����p:$�4 ا ��� �:� a�b+� داةu �6+وع ا ��gا��� ا ������ =�iconga w��*+� ا �'� �ة. ا��%�ام nasa1.7c p�?�� w��*+��$ن congaوg ت ا�5�/���= وإ.4�د��:� ا ������= وا �����= ��q%+اج ������ ا �! ��/! p�.�� '�$ل ������ ،pd��6�ر.� ���z.ا��%[ص وأ�d5�� ا @�� ��� .وا )�(��d��@ ا ��4، ا $�� إ 9*�$ذج �/@ ��ء :���p ����� ا ���4�ت ��� .�دي أيا ��+ ���$ح 1 دراست تأثٍز انشكم انهنذسً نمادة انتقىٌت عهى االجهاداث انذاخهٍت نهمىاد انمتزاكبت عالء حسن عهً .د قغٌ ْٕذعخ اىَ٘اد اىغبٍؼخ اىزنْ٘ى٘عٞخ (received 17 may 2007; accepted 6 september (2007) :مهخص انبحث ٝزيخض اىجحش فٜ اعزخذاً ٍبدح اىزق٘ٝخ ٍِ اىٞبف ٍؼذّٞخ ٍغزَشح ٍِ اىف٘الر اىَقبًٗ ىيظذأ فٜ ٗقذ رْبٗىذ مضٞش ٍِ اىجح٘س ٗاىذساعبد إَٞخ ٍبدح اىزق٘ٝخ ٗرشمٞجٖب (اىًَْٞ٘ )ٍبدح راد اعبط ٍؼذّٜ فٜ اىَبدح االعبط ٍِ ّبحٞخ حغَٖب ٗرشمٞجٖب ٗر٘صٝؼٖب ٗرأصٞش رىل ػيٚ االعٖبداد ثَخزيف اّ٘اػٖب ٍَب رشمض فٜ ٕزا اىجحش ػيٚ ٍؼشفخ ٗدساعخ رأصٞش رغٞش اىشنو اىْٖذعٜ ىَبدح اىزق٘ٝخ ٗرؼذدٕب ػيٚ االعٖبداد اىذاخيٞخ ٗرأصٞشٕب ػيٚ ٍزبّخ اىَشمت ٗثأعزخذاً ؽشٝقخ اىؼْبطش اىَحذدح ثؼذ رؼشػٔ اىٚ ق٘ح .عحت ٍؼْٞخ ٍٗؼشفخ رغٞش االعٖبداد ٗفقب ىزغٞشاىشنو اىْٖذعٜ ىَبدح اىزق٘ٝخ : انمقذمت ّظشا ىالعزخذاٍبد ٗاىَزطيجبد اىظْبػٞخ اىَغزَشح ٗاىَزط٘سح اىزٜ اعزخذٍذ فٖٞب اىَؼبدُ ٗاىغٞشاٍٞل ٗاىيذائِ ٍٗالحظخ اىَضاٝب ٗاىؼٞ٘ة ىٖزٓ اىَ٘اد فقذ رٌ اعزخذاً اىَ٘اد اىَزشامجخ ػيٚ اعبط ٍٞضارٖب اىَزؼذدح ٗثشنو ٗاعغ فٜ رطجٞقبد مضٞشح رجذأ ثبىق٘اسة ٗرْزٖٜ ثبىغفِ اىفؼبئٞخ ٗاالعزخذاٍبد اىطجٞخ ٗاىزٜ ٕٜ -ٍؼذُ)ٍضٝظ ٍِ ّ٘ػِٞ اٗ امضش ٍِ اىَ٘اد فزيل (عٞشاٍٞلث٘ىَٞشٍؼذُ ث٘ىَٞشعٞشاٍٞل خظبئض ٍٞنبّٞنٞخ فشٝذح رؼزَذ ػيٚ مَٞخ [1].ٗؽشٝقخ رشرٞت اىَنّ٘بد اُ إٌ اىخظبئض اىَٞنبّٞنٞخ اىزٜ رَٞض اىَ٘اد اىَزشامجخ ػِ اىَؼبدُ ٕٜ ّغجخ اىظالثخ ( stiffness to density ratio)اىٚ اىنضبفخ strength to)ّٗغجخ اىَقبٍٗخ اىٚ اىنضبفخ density ratio) ثبالػبفخ اىٚ ٍقبٍٗزٖب اىؼبىٞخ ىيناله ٗاطجحذ اىَ٘اد اىَزشامجخ امضش اىَ٘اد اىَغزخذٍخ فٜ طْبػخ اىطبئشاد حٞش دخيذ اٝج٘مغٜ ٗاالسٍٞذ اىنبسثُ٘) ٍزشامجبد فٜ طْبػخ ػذد مجٞش ٍِ اعضاء (اٝج٘مغٜ اىطبئشاد ّٗزٞغخ اىخظبئض اىَٞنبّٞنٞخ اىغذٝذح ىيَ٘اد اىَزشامجخ فقذ اصداد اىطيت ػيٖٞب ثشنو ٗاعغ ٗظٖش اعزخذاٍٖب ػيٚ ٕٞئخ طفبئح رزنُ٘ ٍِ ػذح ؽجقبد ٝنُ٘ ارغبٓ االىٞبف فٖٞب ٍخزيفب ٍِ ؽشٝقخ اىٚ اخشٙ ٗثْغت ٍخزيفخ ٗؽشائق رشرٞت ٍخزيفخ اػزَبدا ػيٚ اىخظبئض اىَطي٘ثخ ىيَبدح ٗمزىل ظٖش اعزخذاً اىَزشامجبد اىٖغْٞخ اىظفبئحٞخ ثشنو ٗاعغ ىيحظ٘ه ػيٚ ٍ٘اد عذٝذح [2 ].قيٞيخ اى٘صُ ٗراد ٍزبّخ ػبىٞخ alkhwarizmi engineering journal vol.3 , no.3 , pp 1-16 (2007) journal engineering journal alkhwarizmi engineering journal ( 2007)161 اىظفحخ 3. اىؼذد3.ٍغيخ اىخ٘اسصٍٜ اىْٖذعٞخ اىَغيذ / ػالء حغِ ػيٜ 2 (انطىر انثانً)مادة انتقىٌت (reinforcement material-:) ٍِ اىٌَٖ دساعخ اىق٘اػذ ىيط٘س اىضبّٜ ٍبدح (matrix) اىَغزخذً ىزق٘ٝخ اىط٘س االٗه االعبط ٗٝطيق ػيٚ اىط٘س اىضبّٜ ثط٘س ٗٝؼشف ػيٚ أّ (reinforcement)اىزق٘ٝخ . اىط٘س اىَغَ٘س ٗاىَزأىف ٍغ اىط٘س االخش رزظف ٍ٘اد اىزق٘ٝخ ثنّٖ٘ب راد ٍقبٍٗخ ٍٗطبؽٞخ ػيٚ ٍخزيفخ ٍْٖب ػبىٞزِٞ ٗاىزق٘ٝخ رزخز اشنبال [ 3].شنو عغَٞبد اٗ ؽجقبد اٗ أىٞبف اىَق٘اح اىَزشامجخ اىَ٘اد ػيٚ اىجحش رشمضٕزا اىْ٘ع ٍِ اىَ٘اد اىَزشامجخ ثبالىٞبف ففٜ ٕزا رغَش االىٞبف فٜ االسػٞخ ٗاىزٜ رنُ٘ اٍب ٍغزَشح اٗ غٞش ٍغزَشح ٍشرجخ اٗػش٘ائٞخ ٗٝغت اُ رَزيل االىٞبف ٍقبٍٗخ ٍٗؼبٍو ٍشّٗخ ػبىٞزِٞ الّزبط ٍ٘اد راد ٍقبٍٗخ ػبىٞخ ّغجخ اىٚ اى٘صُ ٗاالىٞبف ٍغؤٗىخ ثشنو مجٞش رحغِٞ اىخ٘اص اىَٞنبّٞنٞخ فٜ اىَ٘اد اىَزشامجخ، فبالىٞبف اىَغزخذٍخ فٜ رق٘ٝخاىَ٘اداىَزشامجخ ٕٜ اىٞبف (pmcs) راد االعبط اىج٘ىَٞشٛ [ 4 ].اىضعبط ٗاىٞبف اىنبسثُ٘ ٗاىٞبف اىف٘الر اُ اىزغٞش اىَٞنبّٞنٜ ىشنو االعالك عٞحغِ ٕزا اىْ٘ع ٍِ اىزشاثؾ ٗػبدح ٍبرٌ اىيغ٘ء اىٚ ٕزا اىزغٞٞشػْذ اعزخذاً اعالك ٍؼذّٞخ ىزق٘ٝخ ٍبدح ث٘ىَٞش اٗ اىًَْٞ٘ اٗ عٞشاٍٞل ٗاُ رغٞٞش اىشنو اىْٖذعٜ ىٖزٓ االعالك اىف٘الرٝخ ىشنو ٍٗغبحخ اىَقطغ ٗاىط٘ه ٝؤصش ػيٚ اىشثؾ حٞش اُ ٍغبحخ اىَقطغ اىؼشػٜ َٝنِ اُ رنُ٘ دائشٝخ اٗ ٕشٍٞخ اٗ ٍغطحخ ٗاُ االعالك َٝنِ اُ رنُ٘ ٍيغبء اٗ راد ّٖبٝخ رشجٔ اىشفشح (round with end paddles steel wires ) [ 5.] اٗ رٗ ّٖبٝخ ٍغطحخ ٍٗضيٍ٘خ اُ اىؼ٘اٍو اىَغؤٗىخ ػِ رق٘ٝخ االىٞبف ٗاىزٜ ٝغت ٍشاػبرٖب ػْذ رظٌَٞ ٍ٘اد ، ٍشمجخ ٍق٘اح ثبالىٞبف رزشمضفٜ ارغبٓ األىٞبف اىشنو اىْٖذعٜ ، ّغجخ اىط٘ه اىٚ اىقطش دسعخ اىشثؾ ، ٍٗغبحخ اىَقطغ اىؼشػٜ ىيٞف اىنغشاىحغَٜ ، ثِٞ اىيٞف ٗاىَبدح االعبط [ 6].خ٘اص ٍبدح االعبط ٗاىنيفخ ، ىالىٞبف rules of)اعبعٞبد رنِ٘ٝ اىَ٘اد اىَزشامجخ mixtures -:) اُ اىزش٘ٓ اىحبطو فٜ اىَزشامجبد اىَذػَخ ثبالىٞبف ٝؼزَذ ػيٚ ارغبٓ االىٞبف، ففٜ حبىخ االعٖبد اىَْخفغ فبُ مو ٍِ االىٞبف ٗاىَبدح االعبط ْٝفؼالُ اّفؼبال ٍشّب ٗفٜ حبىخ صٝبدح االعٖبد فبُ اىَبدح االعبط َٝنِ اُ رزش٘ٓ رشٕ٘ب ىذّب ثَْٞب رجقٚ االىٞبف فٜ حبىخ اّفؼبه ٍشُ ٝحذس اىفشو فٜ اىَبدحاىَزشامجخ اٍب ثفشو االىٞبف اٗ ثفشو اىَبدح االعبط اػزَبدا ػيٚ َٗٝنِ اُ رنُ٘ ٕزٓ [ 7]ٍطٞيٞخ ميَٖٞب حٞش (anisotropicِ)اىَزشامجبد غٞش ٍزَبصيخ اُ ٍؼبٍالد اىَشّٗخ اىَقبعخ ثأرغبٓ االىٞبف رنُ٘ اػيٚ ٍِ ريل اىزٜ ثبالرغبٓ اىؼَ٘دٛ . ػيٖٞب ٗػيٚ افزشاع ثأُ االىٞبف اىَغزخذٍخ احبدٝخ االرغبٓ ٍْٗزظَخ ٗٗع٘د رشاثؾ ثِٞ االىٞبف ٗاىَبدح االعبط فؼْذ رغيؾ حَو ػيٚ اىَبدح اىَزشامجخ ثأرغبٓ ٍ٘اص اىٚ ارغبٓ االىٞبف فأّٔ عٞز٘صع ػيٚ مو ٍِ اىَبدح االعبط ٗاالىٞبف [ 8]:ٗحغت اىَؼبدىخاألرٞخ fc =ff+fm (1) اىحَو اىَغيؾ ػيٚ اىَبدح (fc)حٞش اُ اىحَو اىَغيؾ ػيٚ االىٞبف ffاىَشمجخ ٗ ٗfmأٗ . اىحَو اىَغيؾ ػيٚ اىَبدح االعبط : َٝنِ طٞبغزٖب ثبىشنو األرٜ σcac=σfaf+σmam (2) :فأُ (ac)ٗثبىقغَخ ػيٚ σc=σf [af\ac]+ σm[am\ac] (3) حٞش اُ [af\ac]مغش اىَغبحخ ىالىٞبف [am\ac]مغش اىَغبحخ ىيَبدح االعبط فأرا مبّذ االىٞبف راد ٍقطغ ػشػٜ ٍْزظٌ ٗراد اؽ٘اه ٍغبٗٝخ اىٚ ؽ٘ه ٍبدح االعبط فأُ مغش اىَغبحخ ع٘ف ٝظجح ٍغبٗٝب ىينغش :اىحغَٜ ىنو ٍِ اىيٞف ٗاىَبدح االعبط ىزا فأُ σc=σfvf+σmvm (4) : ٗحٞش اُ vf+vm=1 : ثبىشنو األرٜ (4)ار عزنُ٘ اىَؼبدىخ σc=σfvf+σm(1-vf) (5) ٗثَب اُ اىزشاثؾ عٞذ ثِٞ االىٞبف ٗاىَبدح االعبط ىزا فبُ االّفؼبه عٞنُ٘ فٜ مو ٍِ االىٞبف ( 2007)161 اىظفحخ 3. اىؼذد3.ٍغيخ اىخ٘اسصٍٜ اىْٖذعٞخ اىَغيذ / ػالء حغِ ػيٜ 3 ٗاىَبدح االعبط ٗثبىزبىٜ ٍغبٗٝب ىيَبدح اىَشمجخ -iso)ٗرؼشف ٕزٓ اىحبىخ ثحبىخ رغبٗٛ االّفؼبه strain) حٞش : єc=єf=єm (6) اّفؼبه اىَبدح اىَزشامجخ(єc)حٞش اُ (єf)اّفؼبه االىٞبف (єm) اّفؼبه اىَبدح االعبط σ=eє أُ ٗثَب ثبىظٞغخ (7)حٞش َٝنِ اىزؼجٞش ػِ اىَؼبدىخ :اىزبىٞخ ecєc=efєfvf+emєm(1-vf) (7) ٍؼبٍو اىَشّٗخ e حٞش اُ vm=1-vfٗثَباُ :-ٝزٌ (7)ٗثزطجٞق اىَؼبدىخ ec=efvf+emvm (8) rule)ثقبػذح اىخيؾ (8)ٗٝطيق ػيٚ اىَؼبدىخ of mixture) ٗرغزخذً الٝغبد ٍؼبٍو اىَشّٗخ ىيَبدح اىَزشامجخ ٗالٝغبد اىنضبفخ ٗمزىل رغزخذً الٝغبد خ٘اص اخشٙ ٍضو اىَقبٍٗخ . ٗاىز٘طٞو اىحشاسٛ ٗاىنٖشثبئٜ ثأرغبٓ اىيٞف :-انتمثٍم بانحاسىب رٌ ثْبء اىَْ٘رط ٗفق ثشّبٍظ رحيٞو االعٖبداد (ansys5.4) ٗرٌ ثْبءاىَ٘اد اىَزشامجخ راد اعبط اىًَْٞ٘ ٍٗبدح اىزق٘ٝخ اىَغزخذٍخ اىٞبف ٍغزَشح ٍِ اىف٘الر اىَقبًٗ ىيظذأ ٗثبىخ٘اص ٗاىقٌٞ اىزبىٞخ ثبىْغجخ ىيَبدح االعبط [ 9]:-(االىًَْٞ٘) modules of elasticity e=70000 n/mm2 possion’s ratio υ =0.32 coeffient of thermal expansion =23e-6 thermal conductivity=0.18 ( stainless steel)اٍب ثبىْغجخ ىَبدح اىزق٘ٝخ :فأخزد اىقٌٞ األرٞخ modules of elastic e=200000 n/ mm2 possion’s ratioυ =0.29 coeffient of thermal=11e-6 expansion thermal conductivity=0.051 ٗقذ رٌ رحَٞو اىَبدح اىَزشامجخ ىَؼشفخ ؽجٞؼـــــــخ االعٖــــبداد اىذاخيٞــــخ ىنــــو ٍـــِ اىَـــــــبدح االعبط ٍٗبدح اىزق٘ٝخ ٍغ رغٞٞشاىشنو اىْٖذعٜ ٗمزىل ػذد ٍٗ٘اقغ االىٞبف فٜ اىَبدح االعبط ٗقشاءح ٍٗؼشفخ ٗاعزخشاط قَٞخ االعٖبداد ػيٚ اىَبدح االعبط ٍٗبدح اىزق٘ٝخ ىنو حبىخ ٗقذ اعزخذً اىشثؾ اىزبً (perfect bounding ) ٗرىل ىغٖ٘ىخ اعزخذاٍٖب فٜ اىجشّبٍظ ٗمزىل ثغجت طؼ٘ثخ ػَو سثؾ غٞش ربً ٗفٜ اىحقٞقخ اُ اىزشاثؾ اىزبً فٜ اىَ٘اد اىَزشامجخ اٍشا الَٝنِ رحقٞقٔ ثبىزطجٞقبد اىؼَيٞخ حٞش الثذ ٍِ ٗع٘د ثؼغ اىفشاغبد ٍبثِٞ اىَبدح االعبط ٗاالىٞبف ىزىل ٝؤخز رىل غبىجب ثْظش االػزجبس اىزغٞٞشاد ثبىزظبٌٍٞ ػْذ اىزطجٞقبد اىؼَيٞخ فٜ ٕزا . اىَغبه رٌ رحَٞو اىَشمت فٜ عَٞغ اّ٘اع اىذساعخ ّٞ٘رِ ثأرغبٓ اىَح٘س 125ٗاىزطجٞق ثق٘ح ٍقذاس ىززٌ اىَقبسّخ فٜ اخزالف قٌٞ (fx)اىغْٜٞ :االعٖبداد ىنو حبىخ ٗمَبٝأرٜ رٌ (1)فٜ اىَْ٘رط اىَ٘ػح فٜ اىشنو 1 رحَٞو اىَبدح االعبط ثذُٗ رق٘ٝخ حٞش مبّذ 25.7ٕ٘ (sx)اىْزٞغخاُ اقو ٍقذاس ىالعٖبد n/mm2 ٕ٘ 550 ٗاػيٚ ٍقذاس n/mm2 ، اىقٌٞ اىذّٞب ٗاىؼيٞب (2)ثَْٞب َٝضو اىشنو . xىالّفؼبه ثبرغبٓ رحَٞو اىَشمت ٍِ اىَبدح االعبط ٍٗبدح 2 اىزق٘ٝخ ثْفظ اىق٘ح ٗاىزٜ ٝنُ٘ فٖٞب شنو ػيٚ شنو (stainless steel) اىٞبف اىزق٘ٝخ ْٗٝزظ (3)ثي٘ك ٍز٘اصٛ اىَغزطٞالد شنو ( von-misses)ػِ رىل اُ اقظٚ اعٖبد اٍب . (4) شنو 98 ٗادّٚ اعٖبد 1750 ٝ٘ػح اىقٌٞ اىذّٞب ٗاىؼيٞب ىالعٖبد (5)اىشنو َٝضو قٌٞ االّفؼبه اىذّٞب (6) ٗاىشنو xثبرغبٓ . ٗاىؼيٞب ثْفظ االرغبٓ رغٞٞش شنو ٍبدح اىزق٘ٝخ ػيٚ ٕٞئخ ثي٘مبد 3 ( 7)شنو (ٍز٘اصٛ ٍغزطٞالد)ٍزشاثطخ ٗرحَٞو اىَشمت ثْفظ اىق٘ح حٞش مبّذ ثقَٞزٞٔ (von-misses)اىْزٞغخ ثأُ االعٖبد ٗمزىل (8)اىذّٞب ٗاىؼيٞب ٍ٘ػحخ فٜ اىشنو اٍب اىشنو ، (9) فٜ اىشنو xاالعٖبد ثبرغبٓ . قٌٞ اىْفؼبه اىزٜ رؼشع ىٖب اىَشمت (10) ( 2007)161 اىظفحخ 3. اىؼذد3.ٍغيخ اىخ٘اسصٍٜ اىْٖذعٞخ اىَغيذ / ػالء حغِ ػيٜ 4 رحَٞو اىَبدح اىَشمجخ ٍغ اخزالف اىشنو -4 ثضٝبدح ػذد اىجي٘مبد (3)اىْٖذعٜ ػِ اىخط٘ح اىَزشاثطخ ػيٚ شنو ٍز٘اصٛ ٍغزطٞالد شنو -von)حٞش مبّذ قَٞخ االعٖبداد (11) misses )5546، 22 مأػيٚ ٗاقو اعٖبد فٞ٘ػح ىْب xاٍب االعٖبد ثبرغبٓ . (12)شنو ٝ٘ػح 11) )ٗاىشنو،ٕزٓ اىقٌٞ (13)اىشنو . اٝؼبxقٌٞ االّفؼبه ثبرغب فٜ ٕزٓ اىخط٘ح رٌ اعزخذاً ٍبدرٜ -5 اىزق٘ٝخ ثبخزالف اىشنو اىْٖذعٜ ىنو ٍَْٖب ٗرٌ رحَٞو اىَشمت ٗمبّذ ،(15)اىشنو -von)اىْزٞغخ الػيٚ ٗاقو اعٖبد misses) اٍب ، (16)ٍ٘ػح ثبىشنو ٝ٘ػحبُ قجٌ مو ٍِ (18)ٗ (17)اىشنيِٞ . ػيٚ اىز٘اىٜ xاالعٖبد ٗاالّفؼبه ثبرغبٓ :انمناقشت واالستنتاجاث فٜ اىجذاٝٔ ٗمَب ٗػحْب عبثقب ٗىغشع ٍقبسّخ رأصٞش اىشنو اىْٖذعٜ ىَبدح اىزق٘ٝٔ رٌ ، ٗرؼذدٕب ػيٚ األعٖبداد داخو اىَشمت رحَٞو ٍبدح االعبط ثذُٗ رق٘ٝخ ٗاىَ٘ػحخ ىغشع اىَقبسّخ ثبىقٌٞ اىَغزحظيخ (1)ثبىشنو ٍِ االعٖبداد ػْذ اعزخذاً ٍبدح اىزق٘ٝخ فٜ اىَشمت ث٘ع٘د ٍبدح اىزق٘ٝخ ىزا ّشٙ ثأُ أػيٚ n/mm2 551 ثيغذ xقَٞخ ىألعٖبد ثأرغبٓ ٗفٜ ٍْطقخ ػٞقخ عذا ػيٚ حبفخ ٍبدح األعبط ٗثْفظ 0.006ٗثأّفؼبالد ثيغذ أػالٕب ( .2)اىَْطقخ اىَ٘ػحخ فٜ اىشنو فٜ اىَبدح اىَشمجخ اىَحز٘ٝخ ىَبدح اىزق٘ٝخ ( 4)رٌ رحَٞو اىَشمت فٜ اىشنو (3)ثبىشنو 1750ىْغذ أُ أػيٚ قَٞخ ىألعٖبداد مبّذ n/mm2 ٍٗزشمضح ػيٚ ٍبدح اىزق٘ٝخ أٍب ٍبدح األعبط فنبّذ رزؼشع ألعٖبد أقو ثنضٞش ٍِ ثَْٞب فٜ اىحبىخ n/mm2 98راىل ٗثقَٞخ ػزٚ n/mm2 551األٗىٚ ثذُٗ رق٘ٝخ مبّذ اىَبدح األعبط ٍَب ٝذه ػيٚ أُ ٍبدح اىزق٘ٝخ ٕٗزا ، قذ رحَو أػيٚ األعٖبداد (اىيٞف) فٜ xْٝطجق أٝؼب ػيٚ األعٖبداد ثأرغبٓ ثبىْغجخ ىَبدح اىزق٘ٝخ ٍٗبدح األعبط (5)اىشنو ػيٚ (6)ٗمزىل األّفؼبه اىزٛ ثيغ فٜ اىشنو ٕٗ٘ أقو قَٞخ ٍِ 0.0049ٍبدح األعبط ثقَٞخ اىحبىخ األٗىٚ ػْذ رغٞش اىشنو اىْٖذعٜ ىَبدح اىزق٘ٝخ شنو قذقيذ (von-misses)ّغذ أُ األعٖبداد (7) ثشنو ٍيح٘ظ ػيٚ ٍبدح األعبط ٗأّحغش ( ، 8)األعٖبد اىؼبىٜ ػيٚ ٍبدح اىيٞف شنو ىألعٖبداد (9)ٕٗزا ٍب ّالحظٔ أٝؼب فٜ اىشنو ( 10)ٗمزىل األّفؼبالد ثبىشنو ( x)ثأرغبٓ ٗػْذ رغٞش اىشنو اىْٖذعٜ ىَبدح اىيٞف ّشٙ أُ األعٖبد قذ (11)فٜ اىشنو (اىزق٘ٝخ) قو ثشنو ٍيح٘ظ ػيٚ مو ٍِ ٍبدح األعبط ٍٗبدح اىزق٘ٝخ حٞش ثيغذ ػيٚ ٍبدح األعبط ٗفٜ ٍْبؽق مضٞشح ٍِ ٍبدح األعبط 5568 ( 12) شنو 616 ىغبٝخ 2.2رشاٗحذ ٍِ ( 13)فٜ اىشنو ( x)ٗمزىل األعٖبداد ثأرغبٓ ٕٗزا ٍب ْٝطجق ػِ أخزالف قٌٞ األّفؼبالد ، فٜ (10)ػِ قَٞزٖب فٜ اىشنو (14)فٜ اىشنو . اىخط٘ح اىغبثقخ فٜ اىخط٘ح األخٞشح اىزٜ رٌ أعزخذاً رؼذد األىٞبف ٍغ أخزالف اىشنو اىْٖذعٜ ىٖب فقذ مبّذ اىْزٞغخ ثؼذ اىزحَٞو شنو (15)شنو رغٞش ٍيح٘ظ فٜ قٌٞ األعٖبداد ٗاىزٜ ( 16) ػيٚ ٍْطقخ ػٞقخ فٜ ٍبدح 5218ثيغ أػالٕب اىيٞف اىزٜ رحَيذ أقظٚ األعٖبداد ثَْٞب ّشىبُ ٍبدح األعبط قذ قو األعٖبد فٖٞب 579 ٗىغبٝخ 2.2ٗرشاٗحذ قٌٞ األعٖبد ٍِ ( 17)ٗفٜ ٍْبؽق ٍزفشقخ فٜ اىَشمت ٗاىشنو حٞش اُ قَٞزٔ xاىزٛ ٝ٘ػح األعٖبد ثأرغبٓ 19 ٗ 2.2رشاٗحذ ػيٚ ٍبدح األعبط ثِٞ ثَْٞب رشمضد األعٖبداد ، (ارغبٓ ٍؼبمظ) ، اىؼبىٞخ ػيٚ ٍبدح اىيٞف ٗثَْبؽق ػٞقخ عذا ٝ٘ػح اُ األّفؼبالد قذ اخزيفذ (18)ٗاىشنو فٜ اىخط٘ح اىزٜ (14)قَٖٞب اٝؼب ػِ اىشنو . عجقزٖب ٍِ مو ٍب ٗسد أػالٓ ٝزؼح ىْب ثأُ ىزغٞش اىشنو اىْٖذعٜ ىَيذح اىزق٘ٝخ ٗمزىل رؼذدٕب داخو ٍبدح األعبط رأصٞش مجٞش ػيٚ أخزالف قٌٞ األعٖبداد ٗأألّفؼبالد ٕٗزا ٍب ٝؼطٜ أٍنبّٞخ مجٞشح ػْذ أػذاد اىزظبٌٍٞ ىيَ٘اد اىَشمجخ .ٗألغشاع ػذٝذح حغت أعزخذاٍبرٖب ( 2007 ) 161 انصفحت 3 انعذد 3مجهت انخىارمً انهنذسٍت ، انمجهذ / عالء حسن عهً.د 5 ( 1)شكم (2)شكم ( 2007 ) 161 انصفحت 3 انعذد 3مجهت انخىارمً انهنذسٍت ، انمجهذ / عالء حسن عهً.د 6 ( 3)شكم ( 4)شكم ( 2007 ) 161 انصفحت 3 انعذد 3مجهت انخىارمً انهنذسٍت ، انمجهذ / عالء حسن عهً.د 7 ( 5)شكم ( 6)شكم ( 2007 ) 161 انصفحت 3 انعذد 3مجهت انخىارمً انهنذسٍت ، انمجهذ / عالء حسن عهً.د 8 ( 7)شكم ( 8)شكم ( 2007 ) 161 انصفحت 3 انعذد 3مجهت انخىارمً انهنذسٍت ، انمجهذ / عالء حسن عهً.د 9 ( 9)شكم ( 10)شكم ( 2007 ) 161 انصفحت 3 انعذد 3مجهت انخىارمً انهنذسٍت ، انمجهذ / عالء حسن عهً.د 10 ( 11)شكم ( 12)شكم ( 2007 ) 161 انصفحت 3 انعذد 3مجهت انخىارمً انهنذسٍت ، انمجهذ / عالء حسن عهً.د 11 ( 13)شكم ( 14)شكم ( 2007 ) 161 انصفحت 3 انعذد 3مجهت انخىارمً انهنذسٍت ، انمجهذ / عالء حسن عهً.د 12 ( 15)شكم ( 16)شكم ( 2007 ) 161 انصفحت 3 انعذد 3مجهت انخىارمً انهنذسٍت ، انمجهذ / عالء حسن عهً.د 13 ( 17)شكم (18)شكم ( 2007 ) 161 انصفحت 3 انعذد 3مجهت انخىارمً انهنذسٍت ، انمجهذ / عالء حسن عهً.د 14 :انزمىس وانمصطهحاث انمستخذمت єx االنفعال بأتجاهx υ poission’s ratio єy االنفعال بأتجاهy vm انكسز انحجمً نهمادة االساس єf االنفعال نالنٍهفvf انكسز انحجمً نالنٍاف єm االنفعال نهمادة االساسfc انحمم انمسهط عهى انمادة انمزكبت e معامم انمزونتff انحمم انمسهط عهى االنٍاف em معامم انمزونت نهمادة االساسfm انحمم انمسهط عهى انمادة االساس fx ًانقىة انمسهطت بأتجاه انمحىر انسٍنσc االجهاد انذي تتعزض نو انمادة انمزكبت σ االجهادσf االجهاد انذي تتعزض نو األنٍاف σm االجهاد انذي تتعزض نو انمادة االساس ( 2007 ) 161 انصفحت 3 انعذد 3مجهت انخىارمً انهنذسٍت ، انمجهذ / عالء حسن عهً.د 15 references: 1. b. raymound,seymonr,” polymeric composite” , alden press, london, 1990. 2 .marc andre meyers & krishan kumar chawla, “ mechanical behavior of material, prentice-hall , inc . 1999. 3. mikell p. groover, “fundamentals of modern manufacturing “prentice hall, upper saddle river, new jersey 1996. 4. robert m. joues ,” mechanics of composite materials” scripta book company, washington d.c., 1975. 5. leslie holliday,” composite materials “applied science publisher ltd, london 1978. 6. derek hull, “an introduction to composite material “, cambridge university , press, 1981. 7. w. bolton,”engineering materials technology” third edition a member of reed elsevier group, 1998. 8. dr.askeland & p. p. phule ," the science & engineering of materials"4 th ed., (2003) 9. w.d.callister,jr.,"materials science and engineering an introduction" 6 th ed., john wiely and sons,inc. 2003. ( 2007 ) 161 انصفحت 3 انعذد 3مجهت انخىارمً انهنذسٍت ، انمجهذ / عالء حسن عهً.د 16 study the influence of the reinforced material geometrical shape on the internal stresses in the composite materials dr. alaa h. ali material engineering dept university of technology abstract: in this paper the reinforced materials manufactured from steel continues fibers are used in aluminum matrix to build a composite material. most of researches concentrated on reinforced materials and its position in the matrix according to its size and distribution, and their effects on the magnitude of different kinds of the stresses, so this paper presents and concentrate on the geometrical shape of reinforced material and its effects on the internal stresses and strains on the composite strength using fem as a method for analysis after loaded by certain force showing the deference magnitudes of stresses according to the different geometrical shapes of reinforced materials. this is an open access article under the cc by license al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 19, no. 3, september, (2023) p. p. 3343 a review on activated carbon prepared from agricultural waste using conventional and microwave activation estapraq ameen taki* sami d. salman** *,**department of biochemical engineering/ al-khwarizmi college of engineering/ university of baghdad/ baghdad/ iraq *email: astapraqameen@gmail.com corresponding author:**email: sami@kecbu.uobaghdad.edu.iq (received 18 january 2023; accepted 18 june 2023) https://doi.org/10.22153/kej.2023.06.001 abstract in the recent years the research on the activated carbon preparation from agro-waste and byproducts have been increased due to their potency for agro-waste elimination. this paper presents a literature review on the synthesis of activated carbon from agro-waste using microwave irradiation method for heating. the applicable approach is highlighted, as well as the effects of activation conditions including carbonization temperature, retention period, and impregnation ratio. the review reveals that the agricultural wastes heated using a chemical process and microwave energy can produce activated carbon with a surface area that is significantly higher than that using the conventional heating method. keywords: agricultural waste, microwave heating, conventional heating, activated carbon. 1. introduction activated carbon is a type of amorphous carbon. which physically or chemically treated to produce large internal surface area and pore volume therefore, it regarded as an excellent adsorbent for different pollutants [1-5]. the specification of the large surface area of the produced activated carbon that may be reaching 3000 m2/gm and the high degree of surface reactivity are the main reason to consider using activated carbon for liquid inorganic and organic or gaseous pollutants elemination [6-10]. various materials and methods were used for activated carbon products such as chemical activation by impregnating the raw material with phosphoric acid, nitric acid, sulfuric acid, potassium hydroxide, sodium hydroxide, zinc chloride and physical activation with co2 or steam followed by carbonization via conventional heating with temperature range from 400 to 800 °c [11, 12] or carbonization via microwave heating [13-15]. in conventional heating, the heat generated at the surface of the treated material and gradually transferred to their interior parts that lead to caloric transport difficulties. whereas the microwave irradiation technique is currently applied in different fields for dielectric materials heating due to its ability to heat materials internally and volumetrically in a short time therefore it reduces energy consumption [16-20]. the removal of pollutants by adsorption using activated carbon is considered the best method as compared with adsorption, evaporation, ion exchange, precipitation, and reverse osmosis methods [21, 22]. the ion exchange method required high operating costs and it was applied for color, heavy metals, nitrate, cod and heavy metals [15-20]. coal, and wood as carbonaceous materials are expensive and still widely used for large-scale production of activated carbon [21]. therefore, the development of low-cost and available raw mailto:sami@kecbu.uobaghdad.edu.iq https://doi.org/10.22153/kej.2023.06.001 estapraq ameen al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 3343 (2023) 34 materials to produce activated carbon for water, and wastewater purification. agricultural waste such as banana stalk [6], alhaji [1], albizia lebbeck and melia azedarach seed shells [5], date palm fronds [4], apricot seed [2], sawdust [23], cotton stalk [16], tobacco stems [18], olive cakes and olive stones [21, 22]. olive-waste cakes [24], date stones precursor [25], rice husks precursor [26], almond shells precursor [27], corn cobs precursor [28], waste tea precursor [29], cherry stones precursor [30], rice bran precursor [31], durian shells precursor [32], herb residues precursor [33], coffee husks precursor [33], spent grains precursor [34], giant reeds precursor [35] and giant reed precursor [36] have been studied for gas and water pollutants treatments. the present article reports literature review on the ac preparation from different types of agricultural waste using chemical activation with conventional and microwave heating. 2. production of activated carbon activated carbon involves different steps including raw materials pretreatment, raw material impregnation with chemical activators followed by carbonization and activators removing, below the production steps of activated carbon with their information. 2.1 raw material pretreatment the raw materials are preliminarily treated including cleaning, drying, crushing, and sieving to the desired particle size before the activated carbon production. the raw material particle size is a very important factor for handling, such as chemical impregnation or mixing; likewise, its influence on the properties of the activated carbon produced. several researchers use agriculture shells or stones as raw materials without crushing, but the crushed and sieved raw materials around 1-2 mm enhanced the handling and materials activation [11], while other researchers investigated the impact of the activated carbon's particle size on the adsorption of the bilirubin bound to albumin [37]. particle sizes in the ranges of 63-100 m, 100-250 m, and 250-500 m were all examined. the outcomes showed that the bilirubin adsorption capacity rose with increasing adsorbent surface area and fell with increasing particle size. the maximum adsorption was obtained with the activated carbon of 1413 m2/g and the particle size of 82 µm. likewise, [37] studied the apricot stones particle size effect on the activated carbon preparation. three ranges of particle sizes were investigated: 0.85-1.7 mm, 1.73.35 mm, and 3.35-4.00 mm. the obtained results show that the minimum particle size enhanced the surface area of the activated carbon produced and consequently, increases the adsorption. 2.2 activation processes for the manufacture of activated carbon, there are two activation processes: physical and chemical activation. physical activation involves the carbonization of the raw material up to 700 °c under an inert atmosphere than the carbonized material is treated under oxidizing atmosphere using air, co2, steam, or their mixture. whereas, in the chemical activation, the raw material is treated with acid, base, or metal salts and then carbonized with temperature range from 400 to 600 °c [38]. 2.2.1 chemical activation with conventional heating different chemical compounds including sodium hydroxide or phosphoric acid, potassium hydroxide, or zinc chloride were used for chemical activation. the depending on the chemical agent used and the type of raw material, the raw material must be impregnated in liquid or solid activation agents for up to 24 hours. the chemical impregnation improves the surface porosity of the produced activated carbon via carbonization due to dehydration, agent evaporation and degradation. the produced activated carbon is washed by distilled water or diluted base or dilute acid to remove residual chemicals from the activated carbon. the main advantages of chemical activation are to enhanced activated carbon yield with high porosity; low energy consumed for carbonization. whereas the disadvantages of the chemical activation are high cost of the chemical activation as well as further washing with distilled or deionized water to remove the residual chemical agents. haimour and emeish [39] have studied the effect of the temperature, chemical impregnation ratio, and impregnation time on the date stone activated carbon yield and the capacity of iodine adsorption. two chemical agents h3po4 and zncl2 for impregnation under similar operating conditions (impregnation ratio, activation time, carbonization temperature. the result showed that the yield and iodine adsorption capacity for activated carbon produced using zncl2 as an impregnation agent was better than those obtained from the impregnation with h3po4. lua and yang estapraq ameen al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 3343 (2023) 35 [40] have studied the temperature, chemical impregnation ratio, and impregnation time parameters effects on the properties of the activated carbon produced from pistachio nut shells. zncl2 impregnation agent was used for activation nitrogen and vacuum conditions, respectively. the results showed that the activated carbon produced under vacuum conditions has better quality compared to that produced under a nitrogen atmosphere. as well the results showed that the product surface area increased with impregnation ratio, impregnation time, and carbonization temperature to a certain limit. several researchers have indicated that the surface area and pore volume of the activated carbon prepared under vacuum conditions was slightly enhanced compared to that produced under a nitrogen atmosphere [40, 41]. [42] have investigated the effect of separately dual impregnation for cherry stones in zncl2 with 3:1 impregnation ratio and 2 h with heating temperature range from 400 °c to 800 °c under nitrogen gas atmosphere on the activated carbon surface area. their results showed that the surface area decreased from 1472 m2/g to 966 m2/g with temperature increasing from 400 °c to 800 °c. [43] have investigated olive seeds' activated carbon surface area produced from a mixture of koh with char at a ratio of 4:1 and carbonization at different temperatures (800-900 °c) for different time intervals of 1, 2, 3, and 4 h. their results showed that the activated carbon surface area increased as the temperature and retention time increased a maximum surface area of 3000 m2/g was obtained at maximum conditions. [44] have conducted an experimental study for the adsorption of cu from aqueous solution by rice husk activated carbon using the central composite methodology to analyze the activation temperature, time, and zncl2 to char impregnation ratio. two quadratic models were generated for the correlation of activated carbon yield and cu removal efficiency as responses with the preparation variables. the results showed that most significant variable was the activation temperature as compared to the other variables and the maximum surface area of the activated carbon was obtained with an activation time of 1.71 hr, and temperature of 500 °c. waste tea-based activated carbon was prepared by [45] using potassium acetate for activation. the effects of impregnation ratio (0.3-0.5), activation temperature (500-800) ºc, and activation time (60-150) min were studied using rsm technique for preparation conditions optimization. three responses were selected; the percentage of yield, methylene blue, and acid blue 29 removals for investigation the results showed that the optimal preparation conditions for maximum surface area with good responses obtained were 800 °c for activation temperature, 1.4 for impregnation ratio, and 120 min for activation time which demonstrated good adsorption capacities. the waste tea was studied also by [46] for activated carbon preparation using k2co3 for activation. the effects of impregnation ratio (0.5:1-1:1), activation temperature (400-900) ºc, and activation time (0.5:1-2:1) hr on the activated carbon surface area were studied. the results show that the activation temperature and the impregnation ratio have the main effect on the pore volume and surface area of the activated carbon produced. in addition, guava seeds, wheat straws, lignite, biomass waste and biomass tremella were investigated to prepare activated carbon using koh and naoh with different impregnation ratio and different carbonization temperatures under nitrogen [47-51]. a summary of different agricultural byproducts as raw materials for activated carbon preparation with different activating agents and conditions with their results respect to surface area obtained are illustrated in table 1. estapraq ameen al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 3343 (2023) 36 table 1, literature summery of chemical activation with conventional heating. material chemical mass ratio activation conditions atmosphere surface area m2/g references alhagi koh 1:1 600 c, 1 hr n2 641.6 [1] date stone h3po4 0.4:1 800 c, 1 hr n2 495 [52] pistachio-nut shell zncl2 0.75:1 1.5:1 400 c, 1 hr 500 c, 2 hr vacuum n2 1647.16 2527 [40] sawdust zncl2 1:1 30 kpa vacuum n2 1079.21 [41] cherry stones zncl2 3:1 400 c, 2 hr 800 c, 2 hr n2 1472 992 [42] olive-seed waste k2co3 ---900 c, 4 hr n2 3049 [43] rice husk co2 ---400 c, 0.5 hr n2 370.75 [44] waste tea ch3co2k 1.4:1 800 c, 2 hr n2 854.3 [45] waste tea k2co3 1:1 900 c, 2 hr n2 1722 [46] guava seeds naoh 3:1 800 c, 1 hr n2 2573.6 [47] wheat straws naoh 4:1 650 c, 2 hr n2 1067 [48] lignite koh 4:1 800 c, 1 hr n2 3036 [49] biomass waste koh 4:1 850 c, 1 hr n2 421.4 [50] biomass tremella koh 5:1 800 c, 3 hr n2 3760 [51] 2.2.2 chemical activation with microwave heating carbonaceous source materials are considered to produce good absorbers; these properties explain the wide usage of microwave heating techniques for activated carbon preparation over the last years as compared to conventional heating. therefore, these techniques have been applied to activated carbon preparation by many researchers in the last five years. cotton stalk precursor was selected with microwave-assisted and chemical activation to prepare activated carbon was studied by [53]. the effects of zncl2 impregnation ratio, microwave power, and microwave radiation time on the yieldactivated carbon produced with methylene blue adsorption capacities were investigated. the results showed that the optimum values of activated carbon preparation conditions were 1.6 g/g, 560 watts, and 9 min for impregnation ratio, microwave power, and radiation time, respectively. likewise, [54] has used cotton stalks precursor with phosphoric acid for chemical activation and microwave heating to optimize the operating conditions for activated carbon preparation. the effects of radiation power, radiation time, h3po4 concentration by volume, and impregnation time, respectively. in addition, apricot seed precursor was used with microwave, and 45% w/w pyrophosphoric chemical activation to prepare activated carbon was studied by [55] the apricot seed was impregnated in 45% w/w of h3po4 at 80 °c (ir of 1: 3) via impregnation time of 4 hr, with a microwave power of 700 watts and radiation time of 20 min. a set of experiments was conducted to investigate the effect of adsorption time, ph, and diclofenac concentration with activated carbon dose on removal efficiency using the central composite method. the results showed that the maximum adsorption efficiency was obtained with the optimum values of adsorption time = 150 min, ph = 3.25, diclofenac concentration = 30 mg/l, and adsorbent dose = 0.267g. isotherm and pseudokinetic models were applied for experimental data which implies monolayer adsorption for isotherm with chemisorption for kinetics models. tobacco stems precursor with k2co3 as a chemical activation agent via microwave heating with their effects on the surface area of the activated area produced was investigated by [18]. the range of microwave power (80-700) watts, radiation time (5-60) min, and impregnation ratio (1-2) on the yield and the adsorption capacities of methylene blue dye were studied. the results demonstrated that the optimum values of 700 w, 30 min, and 1.5:1 for microwave power, radiation time, and impregnation ratio, respectively produced 517.5 mg/g for yield, and 1834 mg/g for adsorption capacity. waste tea precursor via phosphoric acid activation with conventional and microwave heating for activated carbon preparation was studied by [56]. the waste tea was carbonized from 250 °c to 700 °c under n2 atmosphere under a nitrogen atmosphere with different impregnation ratios from 1:1 to 3:1. the waste tea precursor with phosphoric acid was heated in microwave oven prior heating in muffle furnace. the results showed estapraq ameen al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 3343 (2023) 37 that the maximum surface area of activated carbon sample treated with microwave and conventional heating was 1157 m2/g. whereas the maximum surface area of activated carbon sample treated conventional heating was 928.8 m2/g. this implies that samples treated with microwave heating prior conventional heating was reasonably influenced on the micropore structure and surface area. bamboo precursor was used with microwave and h3po4 chemical activation to prepare activated carbon was studied by [57]. the effects of impregnation ratio, microwave power, and microwave radiation time on the yield and surface area of the activated carbon produced were investigated. the results demonstrated that the optimum values of 350 w, 20 min, and 1:1 for microwave power, radiation time, and impregnation ratio, respectively produce 1432 mg/g for surface area, and 48% of activated carbon yield, as well as the results, showed that the microwave-assisted activation demonstrated faster and higher activated carbon yield compared with the conventional heating. jatropha hull precursor via steam and co2 activation with conventional and microwave heating for activated carbon preparation was studied by [58]. the results showed that the activation under steam with conventional and microwave heating offered approximately same yield and porous nature. whereas the values surface area and pore volume were doubled with steam activation with microwave treatment as compared to co2 activation with microwave and conventional heating. investigated coconut shells for activated carbon manufacture [59] utilizing steam, co2, and a co2-steam mixture with microwave radiation. the activation method was explored in two steps, with carbonization under n2 atmosphere at 1000 °c with conventional heating, followed by activation with microwave heating at 900 °c. d. the results showed that the activated carbon produced offered surface area was exceed 2000 m2/g irrespective to the activation, and the activated carbon produced with co2 activation offered highest surface area surface compared steam, co2, and co2-steam mixture. the results also revealed that the microwave-assisted activation demonstrated faster activated carbon produced compared with the conventional heating. based on the above literature review the most efficient of operating parameters ranges of the activation time, activation temperature, and impregnation ratio for activated carbon preparation from agricultural waste using chemical activation with conventional heating techniques were obtained with 1-3 hr of activation time, 400-800 °c of activation temperature, and 0.5-2 of impregnation ratio. whereas the activated carbon prepared from agricultural waste using chemical activation with microwave heating were obtained with 5-15 min of activation time, 350-700 watt of microwave power,and 0.5-2 impregnation ratio. a summary of different agricultural byproducts as raw materials for activated carbon preparation with different activating agents and microwave conditions with their results respect to surface area obtained are illustrated in table 2. table 2, literature summery of chemical activation with microwave heating material chemical mass ratio activation conditions atmosphere surface area m2/g references cotton stalk zncl2 1.6:1 560 w, 9 min n2 794.84 [53] cotton stalk h3po4 0.4:1 400 w, 9 min n2 652.82 [54] apricot seeds h3po4 3:1 700 w, 20 min n2 758. 649 [59] waste tea h3po4 3:1 350 c, 10 min n2 758. 649 [56] bamboo h3po4 3:1 350 w, 20 min n2 1432 [57] jatropha hull steam and co2 ---900 c, 19 min n2 1778.5 [58] coconut shells steam and co2 ---700 w, 15 min n2 2000 [60] according to the above literature review, a comparison between the conventional and microwave heating for activated carbon preparation based on activation time (carbonization), heating mode, gas consuming, and experiments set-up size are given in table 3. estapraq ameen al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 3343 (2023) 38 table 3, summary of the conventional and microwave heating for activated carbon preparation. parameters conventional heating microwave heating activation time • it takes several hours to reach the desired specification which mean extra operating cost. • it takes several minutes to reach the desired specification heating mode • external (surface) heating • internal heating • the temperature gradient transmitted from the hot outer surface of the material to its interior may lead to its damage • the temperature gradient transmitted from the hot interior particles of the material to its outer surface is done rapidly and so highly effective material produced • the conventional heating induced a quick rise in temperature of the surface leading to irregular temperature distribution led to negatively effect on the quality of the product. • the microwave heating induced a quick rise in temperature of the particles, leading to unform temperature distribution, and energy savings. gas consuming • highly gas consumed due to long time of activation • low gas consumed due to short time of activation set-up size • large equipment (furnace) • small equipment (furnace) 3. conclusion • in recent years, attention has turned to microwave technology instead of traditional heating in the preparation of activated carbon from agricultural waste and products as an interesting alternative approach in providing many advantages, including: i. reducing the time required for production, which means lower energy consumption required for activated carbon preparation. ii. reducing the number of steps required for production, consequently reducing the number of reagents and equipment required for activated carbon preparation. iii. (iii) microwave-assisted production technique is more efficient and more economically competitive than that obtained through conventional techniques. • the comparison of activated carbon produced via microwave heating and conventional heating techniques for the same raw materials revealed that microwaves with chemical activation enhanced the surface areas more than those obtained by conventional heating with chemical activation. • the activated carbon properties depend on the raw material type, activation technique, activation agent type, and process conditions including activation temperature, activation time, and impregnation ratio (ir). • the efficiency operating parameters ranges of the activation time, activation temperature, and impregnation ratio for activated carbon prepared from agricultural waste using chemical activation with conventional heating techniques were obtained with 1-3 hr of activation time, 400-800 °c of activation temperature, and 0.5-2 of impregnation ratio. whereas the activated carbon prepared from agricultural waste using chemical activation with microwave heating was obtained with 5-15 min of activation time, 350-700 watt of microwave power, and 0.5-2 impregnation ratio. acknowledgments the authors are grateful to the department of biochemical engineering, al-khwarizmi college of engineering/university of baghdad for the permission to use all the laboratory facilities and the support materials needed in this study. conflict of interest statement all authors declare that they have no conflicts of interest to disclose estapraq ameen al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 3343 (2023) 39 references [1] g. m. a.-h. s. d. salman, "adsorption of para nitro-phenol by activated carbon produced from alhagi " sains malaysiana vol. 49, no. 1, pp. 57-67, 2020, doi: doi: 10.17576/jsm2020-4901-07. 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https://doi.org/10.1016/j.biortech.2010.03.001 https://doi.org/10.1016/j.biortech.2010.03.001 (2023) 33-43، صفحة 3، العدد19دمجلة الخوارزمي الهندسية المجلاستبرق امين تقي 43 الكربون المنشط المحضر من المخلفات الزراعية باستخدام التنشيط التقليدي والميكروويف أستبرق امين تقي* سامي داود سلمان** بغداد / العراق /الكيميائية االحيائية/ كلية الهندسة الخوارزمي/ جامعة بغداد*،**قسم الهندسة astapraqameen@gmail.com*البريد االلكتروني: ad.edu.iqsami@kecbu.uobaghd**البريد االلكتروني: الخالصة تمت زيادة عدد البحوث حول تحضير الكربون المنشط من المخلفات الزراعية والمنتجات الثانوية لهذه المنتجات وذلك لغرض السابقة،في السنوات باستخداماألدبيات حول تحضير الكربون المنشط من النفايات المخلفات الزراعية، مراجعة الىالتخلص من المخلفات الزراعية بشكل مفيد. هذا البحث يقدم ، وتسليط الضوء على تطبيق هذه الطريقة في تحضير الكربون المنشط من خالل بيان تأثير ظروف التنشيط بما في ذلك الميكرويةطريقة التسخين األمواج ونسبة الغمر. وقد كشفت عملية المراجعة أن استخدام المخلفات الزراعية في تحضير الكربون المنشط بواسطة المعاملة التنشيط،وفترة الكربنة،درجة حرارة .لإلنتاجليدية الكيميائية وطاقة الميكروويف للتسخين يمكن أن تنتج الكربون المنشط بمساحة سطحية أعلى بكثير من تلك التي تستخدم طريقة التسخين التق mailto:astapraqameen@gmail.com mailto:sami@kecbu.uobaghdad.edu.iq 2.2.2 chemical activation with microwave heating this is an open access article under the cc by license : al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 21, no. 4, december, (2025), pp. 93105 analysing the effects of switching, conduction and thermal losses on igbt performance in boost dc–dc converters for photovoltaic systems muhanad d. hashim almawlawe department of electronics and communication engineering ,college of engineering, university of al-qadisiyah, al-qadisiyah, iraq email: muhanad.almawlawe@qu.edu.iq (received 9 april 2025; revised 13 september 2025; accepted 19 october 2025; published 1 december 2025) https://doi.org/10.22153/kej.2025.10.003 abstract this study examines the thermal and electrical characteristics of insulated gate bipolar transistors (igbts) in boost direct current (dc)–dc converters used in photovoltaic systems with respect to how switching and conduction losses vary under different operating conditions. the behaviour of ikwh70n65wr6 igbt was measured (plecs software) with load resistances of 5, 10 and 20 ω at switching frequencies of 1–100 khz. important results are as follows: conduction losses prevail at low frequencies and load currents and switching losses increase towards high frequencies. thermal stress is the highest at mid-range frequencies (50–60 khz) and igbt junction temperatures peak to 123 °c. reduced load resistance leads to increased power consumption and total losses, and the value of load matching must be optimised. this study offers critical data regarding the choice and optimisation of igbts to improve efficiency and reliability within the uses of renewable energies. keywords: igbt losses; step-up dc–dc converter; photovoltaic systems; conduction losses; switching losses; thermal control; efficiency optimisation; continuous conduction mode (ccm) 1. introduction renewable energy systems have been used extensively in the recent years as a sustainable substitute to power generation based on fossil fuels, which is linked to the high rate of environmental degradation [1][2]. amongst these systems, photovoltaic (pv) systems utilise the power of the sun and transform it into direct current (dc) voltage by using a number of subsystems. however, the power emitted by solar panels is typically too low and cannot be used directly to charge a battery or be linked to a grid. thus, a voltage-boosting stage is necessary. a boost dc–dc converter is widely used in pv systems to raise low panel voltage to a level required by other downstream systems (e.g. battery storage or grid-tied inverters) [3]-[5]. this converter consists of important elements, such as an inductor; a capacitor; a semiconductor switch, typically a metal–oxide–semiconductor field-effect transistor (mosfet) or an insulated gate bipolar transistor (igbt); and a diode. the synchronised switching behaviour of this converter, which is controlled by the duty cycle, allows increasing the voltage. the assumptions used in the current study are operation in continuous conduction mode (ccm), input voltage (vin) of 48 v, output voltage (vout) of 100 v, switching frequency of 1–100 khz and load resistance of 5–20 ω. the efficiency of the target is approximately 90%. mailto:muhanad.almawlawe@qu.edu.iq https://doi.org/10.22153/kej.2025.10.003 muhanad d. hashim almawl al-khwarizmi engineering journal, vol. 21, no.4, pp. 93105 (2025) 94 the primary motivation of the current study arises from the critical need to enhance the efficiency, reliability and thermal robustness of boost dc–dc converters used in pv systems. 1.1 literature review in this section, a literature review highlights the relationship between the losses of the switching components and the improvement in efficiency of the step-up converter [6][10]. these previous studies are considered under different environmental conditions with various control strategies and authors’ overviews. they focus on the characteristics of igbts and diodes from the following views. 1.1.1 importance of loss minimisation in power electronics one of the grounds for enhancing the effectiveness of step-up dc–dc converters is loss minimisation. esram and chapman in [3] reported that the effectiveness of maximum power point tracking (mppt) techniques in pv systems is closely related to the performance of converters, which, in turn, is dependent on converter losses. efficiency has been pursued with the incorporation of high materials with less loss coefficients, including gallium nitride (gan)-based devices graditi et al. in [8] established that gan-based synchronous rectifiers could significantly lower switching loss in power factor correction boost converters and provide a path towards greater efficiency. almawlawe et al. in [2] used digital converters in low-switching-loss solar panel converters; this technique not only provided an innovation for control strategies but was also the key to minimising switching losses. the aforementioned developments highlight the importance of an overall loss analysis, for conduction and switching losses, with the aim of maximising the performance of a system. 1.1.2 thermal management challenges the problem of heat dissipation is challenging as far as the stable functioning and reliability of igbts in high-frequency converters are concerned. the approach to thermal management in power electronics was defined broadly by rahman et al. in [10] to highlight the effect of losses on the temperature of devices and their dependence on temperature. at high junction temperatures, a threat of thermal stress exists, shortening the life of components, such as diodes and igbts. the reviewed articles examined the dependence of switching frequency, heat sink temperature and junction temperatures on load resistance (r = 5, 10 and 20 ω). for example, when r = 5 ω and f = 100 khz, igbt junction temperatures reach approximately 118 °c. meanwhile, they reach approximately 88 °c when r = 20 ω. these results are consistent with the findings in chaithanakulwat [9], who underlined the significance of highefficiency power conversion in renewable power sources to reduce thermal adversities. 1.1.3 efficiency optimisation techniques the optimisation of the efficiency of step-up dc–dc converters comprise a set of high-level control algorithms, topology redesigning and novel materials. sullivan and zhang in [11] suggested the simplified design of a litz wire that minimised alternating current (ac) losses in inductors, enhancing total efficiency. similarly, the design and use of transformers and inductors in power electronics were discussed by hurley and wölfle [12], with emphasis on core loss modelling via the steinmetz equation. trade-offs between switching frequency and efficiency were also marked in the reviewed papers. although operation at very high frequencies (>100 khz) lowers thermal stress, it causes the difficulty of more switching losses. zhang and peng in [8] performed a step-by-step loss analysis and optimisation of dc–dc converters on pv applications, offering guidelines in the practical selection of components and component working parameters. 1.1.4 control strategies for dynamic performance in boost dc–dc converters, advanced control methods are important for suppressing losses and improving dynamic performance. the implementation of a boost converter with quasisliding mode control presented by trujillo, simeón casanova [13] was demonstrated to achieve better transient response and stability because of its microcontroller-based implementation. hawsawi in [5] discussed switched capacitor boost converters to incorporate solar pv, with particular interest in augmenting mppt dynamically. future research programmes will involve developing adaptive gate-drive methods and real-time control programmes to allow converter operation to be adjusted dynamically to changing load conditions. strategies will be developed to solve the highmuhanad d. hashim almawl al-khwarizmi engineering journal, vol. 21, no.4, pp. 93105 (2025) 95 frequency operation problems and guarantee optimum performance over a significant operating range. 1.1.5 comparison of component characteristics the performance of igbts and diodes in step-up converters is strongly influenced by their switching and conduction characteristics. the reviewed papers provide extensive data on igbt and diode losses under varying frequencies and load resistances. for example, ibgt losses = 28.99 w, diode losses = 31.44 w when r = 5  and f = 10 khz. • r = 20  100 khz, loss in igbt is 13.27 w and that in diodes is 7.19 w. such findings coincide with those of [14], who conducted research on interleaved zero voltage-switching converters to reduce ripple currents and enhance efficiency. the data underscore the importance of selecting components with optimal characteristics for specific applications. 1.1.6 renewable energy applications the incorporation of boost dc–dc converters into renewable energy systems, particularly pv systems, requires appropriate attention on efficiency, reliability and cost. twidell in [1] explained the role of power electronics in renewable energy design, and the necessity of converters with high efficiency to obtain the maximum energy harvest. singh in [4] identified the relevance of converter design in attaining optimal performance. chaithanakulwat in [9] conducted an extensive review of high-efficiency power conversion into renewable energy systems, providing knowledge of state-of-the-art methods for addressing loss reduction. all the aforementioned studies support the necessity to maximise the performance of igbts in pv-integrated systems. reference [15] discussed the losses in dc–dc converters and the techniques for improving efficiency by minimising losses. different techniques for reducing losses in high-frequency dc–dc converters were discussed in [19], [20], [21], including the use of advanced mosfets and optimised circuit designs. 1.1.7 major calculations used to design the set-up converter working in ccm must satisfy the following equation: 𝐷𝑐𝑦𝑐𝑙𝑒 = 1 − 𝑉𝑖𝑛 𝑉𝑜𝑢𝑡 . …(1) the inductor ripple current (δil) should be less than two times the average inductor current (il). 𝐿𝑣𝑎𝑙𝑢𝑒 = 𝑉𝑖𝑛 ∗ 𝐷𝑐𝑦𝑐𝑙𝑒 𝑓𝑠𝑤𝑖𝑡. ∗ ∆𝐼𝐿 , …(2) 𝐶𝑣𝑎𝑙𝑢𝑒 = 𝐼𝑜𝑢𝑡 ∗ 𝐷𝑐𝑦𝑐𝑙𝑒 𝑓𝑠𝑤𝑖𝑡. ∗ ∆𝑉𝑜𝑢𝑡 , …(3) where lvalue is the inductance value, cvalue is the capacitance value, vin is the input voltage, vout is the output voltage, dcycle is the duty cycle, fswit is the switching frequency, il is the inductor ripple current and vout is the output ripple voltage . the basic scheme for the step-up dc–dc converter is depicted in figure 1 [6]. fig. 1. basic step–up dc–dc converter scheme. moreover, the step-up converter contains switches of the mosfet or igbt type and diodes, on which the principle of switching depends on the process of raising or lowering voltages (depending on duty cycle dcycle) . each of these elements contributes to different types of losses. 1) switching losses: they occur during the transition states of a mosfet, wherein energy is lost due to the finite time it takes for the switch to turn on or off [2]. 2) conduction losses: they are resistive losses in the switch, diode and inductor windings; they can increase with current and are influenced by the resistance of these components [9]. 3) core losses: losses in the inductor due to hysteresis and eddy currents within the magnetic core material [11]. muhanad d. hashim almawl al-khwarizmi engineering journal, vol. 21, no.4, pp. 93105 (2025) 96 enhancing the efficiency of boost converters can be achieved by optimising the properties of the aforementioned components, using sophisticated control methods and by redesigning even converter topology in some cases. techniques, such as soft switching, synchronous rectification and the use of materials with low loss coefficients, have been explored and implemented to push efficiency boundaries and minimise losses under varying load conditions [11] [12] [16]-[18],. finally, a table that classifies the aforementioned prior studies summarises the literature review. year author technology employed contribution 2022 shi and li ann with particle swarm optimisation (pso) privacyfocused ids for wsns; pso-enhanced ann performance. 2023 belarbi et al. federated deep learning privacypreserving ids for iot that uses federated learning. 2024 gueriani et al. hybrid cnn–lstm high-accuracy ids that captures spatiotemporal features in iot traffic. 2024 shen et al. federated learning with ensemble knowledge distillation (flekd) enhanced ids performance that addresses data heterogeneity 2024 gowdhaman and dhanapal resnetinception + svm hybrid ids that achieves 99.46% accuracy on nsl-kdd . 2. mathematical model the theoretical part can be strengthened if a clear connection between component physics and the observed simulation results is established through mathematical modelling. the total losses for the step-up converter working in ccm mode is 𝑃𝑙𝑜𝑠𝑠.𝑡𝑜𝑡𝑎𝑙 = 𝑃𝑙𝑐𝑜𝑛𝑑.𝐼𝐺𝐵𝑇 + 𝑃𝑠𝑤𝑖𝑡.𝐼𝐺𝐵𝑇 + 𝑃𝑙𝑐𝑜𝑛𝑑.𝑑𝑖𝑜𝑑𝑒 + 𝑃𝑙𝑠𝑤𝑖𝑡.𝑑𝑖𝑜𝑑𝑒 + 𝑃𝐿 . ...(4) 2.1 igbt conduction losses 𝑃𝑐𝑜𝑛𝑑.𝐼𝐺𝐵𝑇 = 𝑉𝑐𝑒𝑜 ∗ 𝐼𝑐.𝑎𝑣𝑔. + 𝑟𝑐𝑒 ∗ ∗ 𝐼2 𝑐.𝑟𝑚𝑠, …(5) where ,cond igbtp is the conduction power loss in igbt (w), 0cev is the igbt threshold voltage (typically 0.7–1.5 v for igbts) (v), , .c avgi is the average collector current during the conduction period (a), cer is the on-state resistance of the igbt [ω], ,c rmsi is the root mean square (rms) value of the collector current during the conduction period (a). for a step-up converter working in ccm mode, previous currents can be calculated as 𝐼𝑐.𝑎𝑣𝑔. = 𝐼𝐿.𝑎𝑣𝑔. ∗ 𝐷, 𝐼𝑐.𝑟𝑚𝑠 = 𝐼𝐿.𝑟𝑚𝑠 ∗ √𝐷, ...(6) where , .c avgi is the average inductor current (a), 𝐼𝐿.𝑎𝑣𝑔. = 𝑃𝑜𝑢𝑡 𝑉𝑖𝑛∗𝛾 = 𝑉𝑜𝑢𝑡∗𝐼𝑜𝑢𝑡 𝑉𝑖𝑛∗𝛾 , ,rmsli is the rms inductor current (a) and 𝐼𝐿,𝑟𝑚𝑠 = √𝐼𝐿.𝑎𝑣𝑔 . 2 + ∆i𝐿 2 12 . 2.2 igbt switching losses 𝑃𝑠𝑤𝑖𝑡.𝐼𝐺𝐵𝑇 = 𝑓𝑠𝑤𝑖𝑡. ∗ (𝐸𝑂𝑁 + 𝐸𝑂𝐹𝐹), ...(7) where ,swit igbtp is the switching power loss in the igbt (w), switf is the switching frequency (hz), one is the energy loss during the turn-on state (j) and offe is the energy loss during the turn-off state [j]. these energy losses can be further modeled as 𝐸𝑂𝑁 = ∫ 𝑣𝑐𝑒(𝑡) ∗ 𝑖𝑐(𝑡)𝑑𝑡, 𝑡𝑂𝐹𝐹 0 𝐸𝑂𝐹𝐹 = ∫ 𝑣𝑐𝑒(𝑡) ∗ 𝑖𝑐(𝑡)𝑑𝑡. 𝑡𝑂𝑁 0 …(8) these equations can be approximated using datasheet values that are scaled to actual operating conditions: 𝐸𝑂𝑁 = 𝐸𝑂𝑁.𝑟𝑒𝑓 ∗ 𝑉𝑐𝑒 𝑉𝑐𝑒.𝑟𝑒𝑓 ∗ 𝐼𝑐 𝐼𝑐.𝑟𝑒𝑓 ∗ [1 + 𝑇𝑐 ∗ (𝑇𝑗 − 𝑇𝑐𝑗.𝑟𝑒𝑓)], 𝐸𝑂𝐹𝐹 = 𝐸𝑂𝐹𝐹.𝑟𝑒𝑓 ∗ 𝑉𝑐𝑒 𝑉𝑐𝑒.𝑟𝑒𝑓 ∗ 𝐼𝑐 𝐼𝑐.𝑟𝑒𝑓 ∗ [1 + 𝑇𝑐 ∗ (𝑇𝑗 − 𝑇𝑐𝑗.𝑟𝑒𝑓)], …..(9) muhanad d. hashim almawl al-khwarizmi engineering journal, vol. 21, no.4, pp. 93105 (2025) 97 where ,on refe and ,off refe are the turn-on and turn-off energy losses under reference conditions (j), ,ce refv is the reference collector–emitter voltage (v), ,c refi is the reference collector current (a), ,j reft is the reference junction temperature (°c), ct is the temperature coefficient (typically 0.003–0.005 per °c) and jt is the actual junction temperature (°c). 2.3 diode conduction losses 𝑃𝑐𝑜𝑛𝑑.𝑑𝑖𝑜𝑑𝑒 = 𝑉𝐹𝑂 ∗ 𝐼𝐹.𝑎𝑣𝑔 + 𝑟𝐹 ∗ 𝐼𝐹.𝑟𝑚𝑠 2 , …(10) where .,cond diodep is the conduction power loss in the diode (w), fov is the diode threshold voltage (typically 0.7–1.0 v) (v), fr is the on-state resistance of the diode (ω), 𝐼𝐹.𝑎𝑣𝑔 is the average forward current through the diode (a) and ,f rmsi is the rms value of the forward current (a). for a step-up converter working in ccm mode, 𝐼𝐹.𝑎𝑣𝑔. = 𝐼𝑜𝑢𝑡 = 𝑉𝑜𝑢𝑡 𝑅𝑙𝑜𝑎𝑑 ; 𝐼𝐹.𝑟𝑚𝑠 = 𝐼𝑜𝑢𝑡 ∗ √ 1 1−𝐷 . …(11) 2.4 diode switching losses 𝑃𝑠𝑤𝑖𝑡.𝑑𝑖𝑜𝑑𝑒 = 𝑓𝑠𝑤𝑖𝑡 ∗ 𝐸𝑟𝑟, …(12) where .,swit diodep is the switching power loss in the diode (w), and rre is the reverse recovery energy (j). the reverse recovery energy can be calculated as 𝐸𝑟𝑟 = 1 4 ∗ 𝑄𝑟𝑟 ∗ 𝑉𝑅 [1 + 𝑇𝐶.𝑟𝑟 (𝑇𝑗 − 𝑇𝑗.𝑟𝑒𝑓)], …(13) where rrq is the reverse recovery charge (c), rv is the reverse voltage across the diode during switching (v) and ,rrct is the temperature coefficient for reverse recovery (typically 0.005–0.006 per °c). 2.5 inductor losses 𝑃𝐿 = 𝑃𝐿.𝐷𝐶 + 𝑃𝐿.𝐴𝐶 = 𝐼𝐿.𝑟𝑚𝑠 2 ∗ 𝑅𝐷𝐶 + 𝑃𝑐𝑜𝑟𝑒 , …(14) where lp is the total inductor power loss (w); ,l dcp is the dc copper loss (w); ,l acp is the ac loss, which is primarily the core loss (w); and dcr is the dc resistance of the inductor winding (ω). core losses can be estimated using the steinmetz equation: 𝑃𝑐𝑜𝑟𝑒 = 𝑘 ∗ 𝑓𝑠𝑤𝑖𝑡 𝛼 ∗ 𝐵𝑝𝑘 𝛽 ∗ 𝑉𝑐𝑜𝑟𝑒, …(15) where , ,k   are material-specific steinmetz parameters, pkb is the peak magnetic flux density (t) and corev is the volume of the magnetic core (m³). 3. simulation process the simulation process was completed using figure 2, plecs software and detailed data on switching and conduction losses for an igbt device, specifically the ikwh70n65wr6 model. various scenarios are divided into different resistance values (r = 5, 10 and 20 ω) and various frequencies that range from 1 khz to 100 khz. all electrothermal runs were executed in plecs 4.6 on a 1 µs fixed-step solver. conduction and switching losses were computed internally from device characteristics, whilst thermal quantities were obtained with the built-in ‘thermal library’ by using foster coefficient networks. • igbt: infineon ikwh70n65wr6 (650 v, 70 a at 25 °c, tj max 175 °c) • boost diode: infineon idw75e65d1 (650 v, 75 a) • inductor: 220 µh, kool-mμ 60 µ toroid, 14 turns 2 mm × 0.8 mm litz wire, measured rdc = 28 mω • output capacitor: 470 µf/250 v e-cap, esr = 110 mω @ 20 °c, 100 khz • heat sink: rthsa = 1.8 k/w (extruded al 150 mm length, 3 mm fin, natural convection 2 m/s); tim rthcs = 0.35 k/w • ideal gate drive (no overshoot/undershoot); the measured switching energies already include 15% extra margin for layout inductance (estimated 15 nh). 3.1 junction temperature losses • for r = 5  and frequencies of 1–100 khz muhanad d. hashim almawl al-khwarizmi engineering journal, vol. 21, no.4, pp. 93105 (2025) 98 fig. 2. circuit of the setup dc–dc converter. table 1, temperature losses at rload = 5  frequency (khz) heat sink temperature diode junction temperature igbt junction temperature 1 69.5141 134.3826 77.1753 5 82.1744 150.5209 95.1672 10 85.4309 151.4186 99.9818 50 99.4328 -122.9279 60 96.5419 -122.0881 100 84.6633 -118.2692 • for r = 10  and frequencies of 1–100 khz table 2, temperature losses at rload = 10  frequency (khz) heat sink temperature diode junction temperature igbt junction temperature 1 44.4157 68.7946 47.8958 5 47.619 73.4129 53.0108 10 48.8675 73.6855 54.9149 50 58.5155 86.4866 68.4873 60 61.0306 90.2099 71.9595 100 71.5927 106.3471 86.4659 • for r = 20  and frequencies of 1–100 khz muhanad d. hashim almawl al-khwarizmi engineering journal, vol. 21, no.4, pp. 93105 (2025) 99 table 3, temperature losses at rload = 20  0 20 40 60 80 100 120 1000 5000 10000 50000 60000 100000 h e a t s i n k t e m p e r a t u r e frequency heat sink temp. vs frequency r=5 r=10 r=20 fig. 3. heat sink temperature losses vs. frequency. 0 20 40 60 80 100 120 140 160 1000 5000 10000 50000 60000 100000 d io d e j u n c t io n t e m p e r a t u r e frequency (hz) diode junction temp vs frequency r=5 r=10 r=20 fig. 4. diode junction temperature losses vs. frequency. 0 20 40 60 80 100 120 140 1000 5000 10000 50000 60000 100000 i g b t j u n c t i o n t e m p . frequency igbt junction temperature vs frequency r=5 r=10 r=20 fig. 5. igbt junction temperature losses vs. frequency. figures 3, 4 and 5 likely present a comparative graph that shows temperature measurements across three components (igbt junction, diode junction and heat sink) at different switching frequencies. this figure depicts the critical thermal operating points for each component, highlighting that different elements in the converter reach their maximum temperatures at different frequencies. from this figure, we can conclude that the curves likely exhibit rising temperatures as frequency increases, peaking at around 50–60 khz, followed by a decay at extremely high frequencies. moreover, the igbt junction temperatures are the highest (reaching ~123 °c at 50 khz with r = 5 ω), followed by diode junction temperatures (reaching ~151 °c at 10 khz with r = 5 ω), with heat sink temperatures presenting lower values but similar trends. 3.2 switching and conduction losses • for r = 5  and frequencies of 1–100 khz table 4, switching losses at rload = 5  frequency (khz) igbt looses diode looses power 1 19.176 25.3391 2178.6038 5 26.7407 30.437 3733.7786 10 28.9968 31.4379 3733.3485 50 --3699.3581 60 --3697.3194 100 --3693.0962 • for r = 10  and frequencies of 1–100 khz frequency (khz) heat sink temperature diode junction temperature igbt junction temperature 1 36.9866 47.4033 39.5024 5 34.7991 45.7058 37.1773 10 35.3559 45.8791 38.0362 50 39.756 51.4332 44.3082 60 40.8781 53.0029 45.8885 100 45.4653 59.5084 52.3223 200 57.69 77.5262 69.3008 300 71.1633 98.3546 87.7596 muhanad d. hashim almawl al-khwarizmi engineering journal, vol. 21, no.4, pp. 93105 (2025) 100 table 5, switching losses at rload = 10  frequency (khz) igbt looses diode looses power 1 8.6257 10.7904 424.8729 5 11.064 11.5559 1671.302 10 12.024 11.8445 1765.6378 50 19.3185 14.1989 1829.0381 60 21.1788 14.854 1831.4453 100 28.8015 17.7949 1836.2035 • for r = 20  and frequencies of 1–100 khz table 6, switching losses at rload = 20  frequency (khz) igbt looses diode looses power 1 6.1994 5.788 - 5 4.8705 4.9289 699.3105 10 5.3224 5.0338 814.0819 50 8.8221 5.9346 900.7073 60 9.7048 6.174 904.2111 100 13.2742 7.1922 911.1927 0 5 10 15 20 25 30 35 1000 5000 10000 50000 60000 100000 i g b t lo s s e s frequency igbt losses vs frequency r=5 r=10 r=20 fig. 6. igbt switching and conduction losses. 0 5 10 15 20 25 30 35 1000 5000 10000 50000 60000 100000 d io d e l o s s e s frequency diode losses vs frequency r=5 r=10 r=20 fig. 7. diode switching and conduction losses. 0 500 1000 1500 2000 2500 3000 3500 4000 1000 5000 10000 50000 60000 100000 p o w e r frequency power vs frequency r=5 r=10 r=20 fig. 8. dissipated power. figures 6, 7 and 8 present the breakdown of power losses between switching and conduction losses for the igbt and diode components. from this figure, we conclude the following: • conduction losses dominate at lower frequencies. • switching losses become more significant at higher frequencies. • total losses peak at mid-range frequencies (igbt losses of ~29 w and diode losses of ~31 w at 50 khz with r = 5 ω). • lower resistance values demonstrate significantly higher losses than higher resistance values. figure 6 illustrates the trade-off between conduction and switching losses across different operating frequencies, explaining why thermal performance peaks at mid-range frequencies. 3.3 heat sink and diode temperature losses • for r = 5–20  and frequencies of 1–100 khz. table 7, heat sink temperature at rload = 5–20  frequency (khz) at r = 5  at r = 10  at r = 20  1 69.5141 44.4157 36.9866 5 82.1744 47.619 34.7991 10 85.4309 48.8675 35.3559 50 99.4328 58.5155 39.756 60 96.5419 61.0306 40.8781 100 84.6633 71.5927 45.4653 muhanad d. hashim almawl al-khwarizmi engineering journal, vol. 21, no.4, pp. 93105 (2025) 101 0 20 40 60 80 100 120 1000 5000 10000 50000 60000 100000 t e m p . frequency (hz) heat sink temp. vs frequency r=5 r=10 r= 20 fig. 9. heat sink temperature losses vs. frequency and resistance value. figure 9 focuses on the heat sink temperature of igbt behaviour across the full range of investigated frequencies. this figure illustrates how load resistance dramatically affects thermal stress on the heat sink of igbt, with lower resistance (higher current) conditions creating significantly more challenging thermal control requirements. meanwhile, figure 10 specifically emphasises diode temperature behaviour across different frequencies. this figure indicates that the diode exhibits varying thermal stress distributions under various frequencies than under igbt, and the highest temperatures in the diode are at different frequencies. this finding implies that thermal control policies must consider the individual behavioral patterns of the components. table 8, diode temperature at rload = 5–20  frequency (khz) at r = 5  at r = 10  at r = 20  1 134.3826 68.7946 47.4033 5 150.5209 73.4129 45.7058 10 151.4186 73.6855 45.8791 50 -86.4866 51.4332 60 -90.2099 53.0029 100 -106.3471 59.5084 1000 5000 10000 50000 60000 100000 t e m p . freq. (hz) diode temp. vs frequency r=20 r=10 r=5 fig. 10. diode temperature losses vs. frequency and resistance value. 4. results and discussion 4.1 heat sink temperature • the temperature of a heat sink tends to rise with frequency to a given frequency but tends to decline at extremely high frequencies (e.g. 100 khz and higher). • when r = 5 , the highest temperature of the heat sink was recorded as 50 khz (99.4328 °c). then, temperature decreased slightly at higher frequencies. • similar tendencies were noted in the cases of r = 10  and 20 , where temperature was the highest at 50–60 khz and then reduced. 4.2 diode junction temperature • diode junction temperature also rises with increasing frequency, peaking between 50 khz and 60 khz. • for r = 5 , the peak diode junction temperature reached 151.4186 °c at 10 khz, which remained relatively stable until 50 khz before becoming unavailable (‘-’). • at r = 10 , the diode junction temperature continued to rise even at higher frequencies, reaching 106.3471 °c at 100 khz. • for r = 20 , diode junction temperature increased steadily, reaching 98.3546 °c at 300 khz. 4.3 igbt junction temperature • the igbt junction temperature exhibited similar trends as the heat sink and diode junction temperatures. muhanad d. hashim almawl al-khwarizmi engineering journal, vol. 21, no.4, pp. 93105 (2025) 102 • notably, at r = 5 , igbt junction temperature peaked at 122.9279 °c at 50 khz. • for r = 10  and 20 , igbt junction temperatures were lower but still exhibited peaks at around 50–60 khz. 4.4 igbt and diode losses • igbt and diode losses increase with frequency, reflecting higher switching losses at higher frequencies. • for example, at r = 5  and 50 khz, igbt losses were 28.9968 w, and diode losses were 31.4379 w. • at r = 10 , losses were considerably lower compared with r = 5 , particularly at higher frequencies. • at r = 20 , igbt and diode losses were the lowest among the three resistance values. 4.5 power consumption • for power consumption, the losses exhibit a similar trend, peaking to a maximum of 50–60 khz at all resistance values. • with r = 5 , the maximum power consumption was 3733.7786 w at 5 khz, which remained relatively constant until 100 khz. • at r = 10 , power consumption was considerably lower, with the maximum power consumption of 1836.2035 w at 100 khz. • at r = 20 , power consumption was the minimum, with a value of 911.1927 w at a frequency of 100 khz. on the basis of the above information analysed in the context of losses based on switching frequency, we can infer dependable and pegged efficient operation under different circumstances. 1) thermal management: effective thermal control is crucial, mostly at mid-range frequencies (50–60 khz), where heat sink and junction temperatures peak. 2) efficiency: lower resistance values (e.g. r = 5 ) result in higher power consumption and losses, suggesting less efficient operation compared with higher resistance values (e.g. r = 20 ). 3) frequency dependence: operating at very high frequencies (>100 khz) might lead to reduced thermal stress but could introduce other challenges related to switching losses and overall system efficiency. 5. conclusions this work was a systematic research on the thermal and electrical characteristics of igbts in boost dc–dc converters to pv systems at different switching frequencies (1-100 khz) and load resistances (5 , 10 , 20 ). the key findings are as follows: 1. loss mechanisms • conduction losses. they dominate at low frequencies and high load currents. • switching losses. as switching frequency increases, energy lost during switching becomes more prominent, reaching its highest point within the 50–60 khz range. 2. thermal performance • igbt junction temperatures. they peak at 123 °c (r = 5 ω, 50 khz), whilst diode junctions reach 151 °c (r = 5 ω, 10 khz). • heat sink temperatures. the shared patterns in the data highlight the importance of a well-designed cooling system. 3. efficiency trade-offs using a smaller resistor (e.g. 5 ω) results in more wasted energy (approximately 3.7 kw) and lower overall efficiency. meanwhile, a larger resistor (e.g. 20 ω) reduces this energy waste, but its use must be carefully coordinated with the operating frequency to maintain good balance amongst different types of energy loss. 4. design implications • optimal frequency ranges (≈20–50 khz) exist to minimise total losses whilst maintaining thermal limits. • component selection (e.g. igbt/diode characteristics) must align with operational conditions to ensure reliability. limitations of the study this study’s conclusions are limited by several factors: firstly, the findings are based solely on computer simulation (using plecs) and have not been confirmed with a physical model. that is, real-world issues, such as electrical interference, measurement errors, heat transfer between components and manufacturing variations in parts, were not considered. secondly, the simulation’s heat model is a simplification based on manufacturer data. it does not capture the complex, 3d manner in which heat actually spreads or changes over time, nor does it muhanad d. hashim almawl al-khwarizmi engineering journal, vol. 21, no.4, pp. 93105 (2025) 103 factor in how airflow and surrounding temperature changes will affect performance in a real application. thirdly, this research only examines a standard and basic converter design with simple controls. it does not explore how more advanced designs or smarter control methods can change the results. finally, this investigation was narrow, focusing only on a single specific type of transistor (ikwh70n65wr6 igbt) and its diode. the results may not be generalised to other igbt generations, sic/gan devices or different diode technologies with superior reverse recovery characteristics. future work future research directions: • developing advanced control algorithms and adaptive gate-drive techniques to minimise losses and improve dynamic performance in boost dc– dc converters for pv systems. • exploring innovative thermal management strategies to address the challenges posed by highfrequency operation and varying load conditions. acknowledgements we extend our heartfelt gratitude and deepest appreciation to al-qadisiyah university, particularly the department of electronics and communication, for their unwavering support, guidance and resources throughout this endeavour. 6. references [1] twidell, john. renewable energy resources., second edition,: taylor&francis, 2021. 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المجلد مهند ضياء هاشم المولوي 105 في مغيرات التيار المستمر الرافعه igbt تحليل تأثير خسائر التبديل والتوصيل على أداء .ألنظمة الكهروضوئيةالمستخدمه في أ مهند ضياء هاشم المولوي االلكترونيك واالتصاالت، كلية الهندسة، جامعة القادسية، القادسية، العراق قسم muhanad.almawlawe@qu.edu.iq :البريد االلكتروني المستخلص المعزولة البوابة القطب ذات ثنائية الترانزستورات أداء التبديل والتوصيل على تأثير خسائر في الدراسة التيار (igbts)تبحث هذه داخل محوالت في ظل ظروف تشغيل مختلفة ، بما في igbtsيفحص البحث السلوك الحراري ل . (pv)المستمرالتصعيدية ، المصممة خصيصا لألنظمة الكهروضوئية يتم .اإلخراج /، ومعلمات اإلدخال كيلو هرتز 100كيلو هرتز إلى 1، وترددات التبديل تتراوح من (ω 20و ω 10و ω 5ذلك مقاومة الحمل المختلفة ) وخسائر الطاقة لتوفير فهم igbtتحليل المقاييس الرئيسية مثل درجة حرارة المشتت الحراري ودرجة حرارة تقاطع الصمام الثنائي ودرجة حرارة تقاطع الكفاءة لمقايضات أكثر .شامل التبديل بينما تصبح خسائر ، الحمل األعلى المنخفضة وتيارات الترددات التوصيل تهيمن على إلى أن خسائر النتائج تشير كيلو 60-50)يظهر التحكم الحراري كعامل حاسم ، حيث تصل درجات الحرارة إلى ذروتها عند ترددات متوسطة المدى ) .وضوحا عند الترددات األعلى هالك الطاقة والخسائر ، مما يسلط الضوء على باإلضافة إلى ذلك ، تؤدي قيم المقاومة المنخفضة إلى زيادة است .هرتز قبل أن تنخفض عند الترددات العالية جدا ، يوفر هذا البحث إرشادات مهمة الختيار وتحسين أداء plecsمن خالل المحاكاة باستخدام برنامج .أهمية تحسين ظروف الحمل من أجل التشغيل الفعال igbts ستركز األبحاث المستقبلية على خوارزميات التحكم المتقدمة وتقنيات محرك البوابة التكيفية .لزيادة الكفاءة والموثوقية في تطبيقات الطاقة المتجددة لتقليل الخسائر وتعزيز األداء الديناميكي في محوالت التيار المستمرالتصعيديه والمستخدمه في منظومات الطاقه الشمسيه. mailto:muhanad.almawlawe@qu.edu.iq 138 al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 4, no. 3, pp 138-145 (2008) multiwavelet and estimation by interpolation analysis based hybrid color image compression ali hussien miry departement of mechatroncis engineering/al-khwarizmi collage of engineering/university of baghdad e-mail: alihussien76@yahoo.com (received 4 march 2008; accepted 21 july 2008) abstract nowadays, still images are used everywhere in the digital world. the shortages of storage capacity and transmission bandwidth make efficient compression solutions essential. a revolutionary mathematics tool, wavelet transform, has already shown its power in image processing. the major topic of this paper, is improve the compresses of still images by multiwavelet based on estimation the high multiwavelet coefficients in high frequencies sub band by interpolation instead of sending all multiwavelet coefficients. when comparing the proposed approach with other compression methods good result obtained. keywords: image processing, multiwavelet transform. 1. introduction with the increasing use of multimedia technologies, address needs and requirements of multimedia and internet applications, many efficient image compression techniques, with considerably different features, have recently been developed. image compression techniques exploit a common characteristic of most images that the neighboring picture elements [1-3]. the aim of image compression is to reduce the size of an image with or without loss of information (lossy or lossless compression). one of the most commonly used lossy compression methods is that of transform coding using one of the many images transforms available. the idea of any transform is to transform the image into a new domain, where the image is now represented (approximated) by a set of decorrelated coefficients. however, in order to achieve (lossy) compression, the coefficients containing less important information are removed while those with the most important information are kept. at this point, we can inspect qualitatively (visually) and quantitatively (signal to noise ratio) the compressed image by reconstructing it via the inverse transformation.[4] the discrete wavelet transform (dwt) is being increasingly used for image coding due to the fact that dwt supports features like progressive image transmission (by quality, by resolution). although this advantage of the transform but may be obtain small signal to noise ratio. this depended on the nature of the image. algorithms based on wavelets have been shown to work well in image compression. theoretically, multiwavelets should perform even better due to the extra freedom in the design of multifilters [5]. this paper is organized as follows. section 2 describes color images, the process of the multiwavelets transform scheme and analysis all the filters and gives a brief overview of the interpolation theorems. the proposed algorithm based on multiwavelets transform and interpolation is given in the section 3. finally, conclusions are presented in section 4. 2. backgrounds 2.1 color image each component or layer of the image can be viewed as a single channel image, which, under particular conditions, can be analyzed independently from the others. this is not the case mailto:alihussien76@yahoo.com ali hussien miry al-khwarizmi engineering journal, vol. 4, no. 3, pp 138-145 (2008) 139 for rgb space, because, if two channels are fixed, human visual perception is very sensitive to small changes of the value of the remaining channel .in a typical color image, the spatial intercomponent correlation among the red, green, and blue color components is significant. in order to achieve good compression performance, correlation among the color components is first reduced by converting the rgb image into a decorrelated color space [6].the color space conversion modules transforms red green blue (rgb) encoded data into ycbcr coding. y represents luminance (based on inverse gamma-distorted data) and cbcr represents chrominance [7].the advantage of converting the image into luminance-chrominance color space is that the luminance and chrominance components are very much decor related between each other the transformation from rgb to ycbcr is done based on the following mathematical expression[1,8]. )1...( 128 128 0 0813.0418.05.0 5.0331.0168.0 114.0587.0299.0                                             b g r c c y r b accordingly, the inverse transformation from ycbcr to rgb is done as [1, 8]. from eq. (2) we note that cr=red component – luminance component and cb=blue component – luminance component [1]. 2.2 multiwavelet transform multiwavelets constitute a new chapter which has been added to wavelet theory in recent years. recently, much interest has been generated in the study of the multiwavelets where more than one scaling functions and mother wavelet are used to represent a given signal [6].multiwavelets bases have been investigated for several years now. with this generalization, it is possible to construct orthogonal (real-valued) bases for which the scaling functions have compact support, approximation order greater than 1, and symmetry, which is not possible with traditional wavelet bases [7]. )2...( 128 128 0 077.11 71.034.01 4.101                                            r b c c y b g r multiwavelets are very similar to wavelets but have some important differences. in particular, whereas wavelets have an associated scaling function φ(t) and wavelet function ψ(t) , multiwavelets have two or more scaling and wavelet functions. 2.3 theory of multiwavelets in particular, whereas wavelets have an associated scaling function (t) and wavelet function (t), multiwavelets have two or more scaling and wavelet functions. for notational convenience, the set of scaling functions can be written using the vector notation (t)[1(t), 2(t)… r(t)] t , where (t) is called the multiscaling function. likewise, the multiwavelet function is defined from the set of wavelet functions as (t)[1(t), 2(t)… r(t)] t . when r=1, (t) is called a scalar wavelet, or simply wavelet. while in principle r can be arbitrarily large. the multiwavelets studied to date are primarily for r=2. the multiwavelet two-scale equations resemble those for scalar wavelets [9].     k k ktht )2(2)( …(3)    k k ktgt )2(2)( …(4) note, however, that {hk} and {gk} are matrix filters, i.e., hk and gk are r r matrices for each integer k. the matrix elements in these filters provide more degrees of freedom than a traditional scalar wavelet. these extra degrees of freedom can be used to incorporate useful properties into the multiwavelet filters, such as orthogonality, symmetry, and high order of approximation. the key, then, is to figure out how to make the best use of these extra degrees of freedom. one famous multiwavelet filter is the ghm filter proposed by geronimo, hardian, and massopust. the ghm basis offers a combination of orthogonality, symmetry, and compact support, which can not be achieved by any scalar wavelet basis. according to eqs. (3) and (4) the ghm two scaling and wavelet functions satisfy the following two-scale dilation equations[7]                k k kt kt h t t )2( )2( 2 )( )( 2 1 2 1     …(5)                k k kt kt g t t )2( )2( 2 )( )( 2 1 2 1     …(6) ali hussien miry al-khwarizmi engineering journal, vol. 4, no. 3, pp 1-7 (2008) 140 where hk for ghm system are four scaling matrices h0, h1, h2, and h3,                                                        0 20 1 00 , 210 3 20 9 00 , 2 1 20 9 0 25 3 , 210 3 20 1 5 4 25 3 32 10 hh hh also, gk for ghm system are four wavelet matrices g0, g1, g2, and g3,                                                            0 210 1 0 20 1 3 , 10 3 210 9 210 3 20 9 2 , 0 210 9 2 1 20 9 1 , 10 3 210 1 210 3 20 1 0 gg gg 2.4 multiwavelet in comparison with wavelet the multiwavelet idea originates from the generalization of scalar wavelets. instead of one scaling function and one wavelet, multiple scaling functions and wavelets are used. this leads to more degree of freedom in constructing wavelets. therefore opposed to scalar wavelets, properties such as orthogonality, symmetry, vanishing moments, can be gathered simultaneously in multiwavelets, which are fundamental in signal processing. the increase in degree of freedom in multiwavelets is obtained at the expense of replacing scalars with matrices, scalar functions with vector functions and single matrices with block of matrices. however, prefiltering is an essential task which should be performed for any use of multiwavelet in the signal processing [9]. 2.5 interpolation interpolation is a process for estimating values that lie between known data points. it has important applications in areas such as signal and image processing [10]. its most general form of this theorem is yi = interp1(x,y,xi,method). y is a vector containing the values of a function, and x is a vector of the same length containing the points for which the values in y are given. xi is a vector containing the points at which to interpolate. method is an optional string specifying an interpolation method: nearest neighbor interpolation this method sets the value of an interpolated point to the value of the nearest existing data point. linear interpolation this method fits a different linear function between each pair of existing data points, and returns the value of the relevant function at the points specified by xi. cubic spline interpolation this method fits a different cubic function between each pair of existing data points, and uses the spline function to perform cubic spline interpolation at the data points. nearest neighbor interpolation is the fastest method. however, it provides the worst results in terms of smoothness. linear interpolation uses more memory than the nearest neighbor method, and requires slightly more execution time. cubic spline interpolation has the longest relative execution time, although it requires less memory than cubic interpolation [11-13]. it produces the smoothest results of all the interpolation methods. you may obtain unexpected results, however, if your input data is non-uniform and some points are much closer together than others. cubic interpolation requires more memory and execution time than either the nearest neighbor or linear methods. 3. proposed method the following steps are followed in the encoder phase: 1. color space conversion:-in this step the color components rgb are transformed to ycbcr according to eq (1). 2. multiwavelet transform:-in this step 2d multiwavelet transform is applied on the input image according to eq (5) and eq (6) after resizing it to power of two [256 x 256]pixels. 3. thresholding:the multiwavelet coefficients whose magnitude values are less than a prespecified value called (threshold value) are set zero (discarding). so that the transformed image after thresholding will contains long strings of zeros ali hussien miry al-khwarizmi engineering journal, vol. 4, no. 3, pp 138-145 (2008) 141 4. ommting some of multiwavelet coefficients. after thresholding, most of multiwavelet coefficients in high frequencies subbnads are zero (especially for high compression ratio).for this reason, some of the of multiwavelet coefficients in these bands can be omitted by sending one coefficient only from each k coefficients, (where a k is positive integer, that affects on the compression ratio) figures (1-7) show the original image, and their components fig. 1. original image. fig. 2. blue component. fig. 3. y component. fig. 4. cr component. fig. 5. red component. fig. 6. green component. fig. 7. cb component. 3.1 decompressed decompression steps the steps of decompression process are: step 1: estimating the missing multiwavelet coefficient that lie in high frequency sub bands by using interpolation. step 2: inverse multiwavelet transformation is applied on the image. step 3: inverse transformation from ycbcr to rgb is applied on the image. figure 8 shows the flowchart of compressed procedure while figure 9 shows the decompressed procedure. 4. simulation results in this section, the implementation results and the performance of the proposed algorithm when compared to other available approaches are presented. the proposed algorithm is implemented using matlab package with test images with size 256*256 pixels. table no.1 shows different compression ratio (93%, 95%, 98%, 99%) and the psnr in db obtained using the proposed method and wavelet based compression for different color images as briefly discussed in section 2.4, wavelet and muiltwavlet transform is a powerful signal processing algorithm, and thus many researchers have proposed different modified versions of that algorithm. in this research, multiwavelet and estimation by interpolation is implemented. as seen in table 1, for most tested images, with the same compression ratio, the psnr obtained from the proposed algorithm is greater than psnr of other methods (wavelet and jpeg 2000). the difference between psnr of a proposed method and other increase especially in high compression ratio (columns 2 and 3 of table 1). this is due to that multiwavelet coefficients at very high compression are zero (or close to zero) and by interpolation the actual values of the ali hussien miry al-khwarizmi engineering journal, vol. 4, no. 3, pp 1-7 (2008) 142 coefficients or at least nearest to the actual values coefficients can be estimated. fig. 8. compression procedure. fig. 9. decompression procedure. start input compressed image 2d multiwavelet for an image 2d inverse multiwavelet for an image estimation the lost coefficients by interpolation color conversion from ycbcr to rgb end of decompressed start input compressed image 2d multiwavelet for a image 2d inverse multiwavelet for a image estimation the lost coefficients by interpolation color conversion from ycbcr to rgb end of decompressed ali hussien miry al-khwarizmi engineering journal, vol. 4, no. 3, pp 138-145 (2008) 143 table 1 compression ratio vs. psnr. pic. no. ratio psnr(db) 93% 95% 98% 99% picture. 1 proposed algorithm 33.835 db 31.8150 db 24.872 db 28.11 db wavelet 27.092 db 26.7032 db 23.8323 db 21.8010 db jpeg 2000 27.9 db 27.6 db 24.01 db 22.2 db 2 proposed algorithm 32.2 db 30.4 db 27.9 db 26.5 db wavelet 31.5 db 28.5 db 24.1 db 23.4 db jpeg 2000 32 db 28.9 db 25.1 db 23 db 3 proposed algorithm 33.961 db 33.2676 db 31.8781 db 30.0416 db wavelet 33.835 db 31.8150 db 23.8323 db 28.11 db jpeg 2000 33.7 db 31.9 db 28.9 db 28.03 db 5. conclusions in this study, the compression approach for color images using the multiwavelet and estimation by interpolation based mode of operation is proposed. based on the simulation results obtained in this study, the proposed approach can achieve highcompression ratio with high snr. multiwavelet offers the advantages of combining symmetry, and orthogonality, properties not mutually achievable with scalar wavelet systems. however, multiwavelet differ from scalar wavelet systems in requiring two or more input streams to the multiwavelet filter bank according to the results in table (1), the obtained subjective tests show the superiority of the proposed algorithm when compared to the wavelet and jpeg 2000 approaches. an important advantage of this method appears at high compression ratio. the proposed algorithm performs even better for smoothness images because the interpolation methods can easily estimate the data smooth region. 6. references [1] m. golner, w. mikhael, “region based variable quantization for jpeg image compression” leee 2000. [2] m. lin, “a hardware architecture for the lzw compression and decompression algorithms based on parallel dictionaries” international symposium on vlsi technology, systems, and applications, june 3–5, 2000. [3] m. tian, s. wei, l. zhi liao “an investigation into using singular value decomposition as a method of image compression” proceedings of the fourth international conference on machine learning and cybernetics, guangzhou, 18-21 august 2005 ieee. ali hussien miry al-khwarizmi engineering journal, vol. 4, no. 3, pp 1-7 (2008) 144 [4] v. strela, p. n. heller, g. strang, p. topiwala, and c. heil, “the application of multiwavelet filter banks to image processing”, ieee trans. image processing, vol. 8, pp. 548–562, apr. 1999. [5] j. tham, l.. shen, s. lee, and h. h. tan, “a general approach for analysis and application of discrete multiwavelet transforms” ieee trans. signal processing, vol. 48, pp. 457– 464, feb. 2000. [6] m. moazam, a. taheri, m. pooyan” multiwavelet and biological signal processing”, transactions on engineering, computing and technology v2 december issn pp.1305-5313, 2004. [7] i. selesnick,” multiwavelet bases with extra approximation properties”, ieee trans. inform.theory, vol. 46, no.11, pp. 28982908, november 1998. [8] t. acharya, p.tsai “jpeg2000 standard for image compression concepts, algorithms and vlsi architectures” a john wiley & sons, inc., publication, 2005. [9] b. martin and a. bell “new image compression techniques using multiwavelets and multiwavelet packets “ieee trans. image processing, vol. 10, no.4, pp. 500–510, april 2001. [10] m. dekker, ”numerical methods for engineers and scientists” second edition, inc. new york. basel 2002. [11] z. john, “an introduction to numerical analysis for electrical and computer engineers”. ,inc. publication 2004. [12] g. collins, “fundamental numerical methods and data analysis”, ii 2003. [13] s. conte, “elementary numerical analysis” an algorithmic approach mcgraw-hill book company 1980. ali hussien miry al-khwarizmi engineering journal, vol. 4, no. 3, pp 138-145 (2008) 145 استخذاو متعذد تحويم انمويج وطريقة االستكمال نضغظ انصور انمهونة عهي حسين مري جايعت بغذاد / كهيت هُذست انخىاسصيي/ قسى هُذست انًيكاحشوَكس انخالصة في انىقج انحاضش اصبحج عًهيت خضٌ انصىس واسسانها حاخز اهخًايا بانغا وانعذيذ يٍ انبحىد حخطشق انً يسانت ضغظ انصىس حيذ يسخخذو يخعذد ححىيم انًىيج بشكم كبيش في هزا انًجال وفي هزا انبحذ َقخشح طشيقت جذيذة حعخًذ عهً هزا انخحىيم وكزنك عهً انخخًيٍ ورنك باسسال عذد قهيم يٍ يعايالث ححىيم يخعذد انًىيج ويٍ رى حخًيٍ انًعايالث انًفقىدة عىضا عٍ اسسانها . بىاسطت َظشياث االسخكًال .وانُخائج انًسخحصهت يٍ هزة انطشيقت حعخبش افضم يٍ انطشق االخشي وباالخص في َسب انضغظ انعانيت. جًعيا this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 20, no. 2, june, (2024), p p. 7385 assessment of foot deformities in patient with knee osteoarthritis ruba musaid*, aseel ghazwan** and waleed a. al-saadan *** *,**department of biomedical engineering, al-nahrain university, baghdad, iraq *** consultant orthopedic surgeony, medical city teaching complex, baghdad, iraq corresponding author: *email: st.ruba.m.taha@ced.nahrainuniv.edu.iq **email: aseel.m.ali@nahrainuniv.edu.iq ***email: waleedbgh@arab-board.education (received 20 july 2023; accepted 11 september 2023; published 1 june 2024) https://doi.org/10.22153/kej.2024.09.001 abstract foot morphology evaluation techniques are commonly used to evaluate foot abnormalities. the foot is essential for keeping the biomechanical performance of the lower extremities. knee osteoarthritis is a pathological condition that could lead to foot deformities. the major goal of this study was to investigate the prevalence of foot deformity in patients with knee osteoarthritis. another goal was to quantify the impact of pain and the severity of osteoarthritis foot morphological changes in knee osteoarthritis patients.a total of seventy-eight participants took part in this study, including forty-six non-pathological subjects and thirty-two subjects diagnosed with knee osteoarthritis. foot characteristics were assessed by a podoscope that can automatically estimate foot morphological parameters including arch index, chippaux-smirak index, staheli index, weisflog's index, clarke’s angle and hallux valgus angle. numerous foot-related variables have been connected in a direct manner to knee osteoarthritis. particularly, those who had knee osteoarthritis had substantially higher values for the arch index (0.29±0.018; p=0.00), chippaux-smirak index (0.55±0.5; p=0.00), staheli index (0.77±0.7; p=0.00), and weisflog's index (2.7±0.25; p=0.00) than those who did not have this disease. furthermore, their clarke's angle and hallux valgus angle exhibited high values of (30.27±2.7) and (13±1.8), respectively. there were also significant correlations found within the knee osteoarthritis group. there was, for example, a substantial positive correlation between the arch index and the chippaux-smirak index (0.767; p=0.00), the arch index and the staheli index (r=0.35; p=0.04), and the chippaux-smirak index and the staheli index (r=0.44; p=0.01). in terms of foot abnormalities, the midfoot (333.528.6; p=0.00) was more significant than the rearfoot (604.25±31.2; p=0.85) and hindfoot (433.3±35.2; p=1.66). with association values of (r=0.4; p=0.02) and (r=0.4; p=0.04), the arch index and chippaux-smirak index were both significantly linked with the severity of knee osteoarthritis.foot abnormalities are substantially more prevalent in persons with knee osteoarthritis. collapsed medial longitudinal arch, transverse arch, and hallux valgus are all variables to consider in the management of knee osteoarthritis. healthcare providers may target knee osteoarthritis effects on midfoot morphology with focused therapies. custom orthotic devices, footwear adjustments, and particular workouts may enhance midfoot stability and alignment. assessing foot morphology allows healthcare providers to enhance knee osteoarthritis therapy and patient results. keywords: foot deformation; osteoarthritis; arch index; chippaux-smirak index; staheli index 1. introduction knee osteoarthritis (koa) is a degenerative joint ailment that gradually becomes worse over time. it is characterised by chronic joint pain and stiffness, which can severely impede a person's physical function and ability to do everyday tasks. koa is a primary source of functional impairment and is expected to impact roughly 18% of those aged 45 and over. this disorder may have larger implications on the lower limb. it has the ability to change the alignment of the whole lower leg, including the knee, hip, and ankle joints. this altered alignment mailto:st.ruba.m.taha@ced.nahrainuniv.edu.iq mailto:aseel.m.ali@nahrainuniv.edu.iq mailto:waleedbgh@arab-board.education https://doi.org/10.22153/kej.2024.09.001 ruba musaid al-khwarizmi engineering journal, vol. 20, no.2, p.p. 113(2024) 74 places additional stress on the ankle joint, this can lead to degeneration and the development of ankle joint disorders. individuals with koa should seek appropriate medical care and management measures to relieve pain, enhance function, and limit the course of the illness. treatment options may include pain management strategies, physical therapy, exercise, assistive equipment, and, in certain situations, surgical proceduresconsulting with a healthcare expert, such as an orthopaedic specialist or rheumatologist, can lead the most suited treatment method for each individual's unique circumstance [1]. flatfoot, a disorder defined by a collapsed or low arch in the foot, can contribute to the increased severity of disability in patients with koa. specifically, flatfoot can result in excessive rotation of the knee joint [2]. it is still unknown if abnormalities such as flatfoot are a direct cause or a risk factor for the development of koa. traditionally, osteoarthritis (oa) was diagnosed based on the radiological appearance of the afflicted joints. in 1957, kellgren and lawrence established radiographic criteria for oa [3], they were eventually approved by the world health organisation during a 1961 session in milan[4]. kellgren and lawrence's categorization approach categorises oa into five phases. a healthy knee (stage 0) does not have osteoarthriti. the severity increases as the medical condition worsens. severe oa is categorised as stage 4, indicating significant joint degeneration. stage 4 is the most severe variety of oa, with each stage signifying a more advanced condition of the disease. this grading system offers a standardised framework for characterising the radiological appearance and severity of oa. traumatic injury, genetic susceptibility, obesity, and poor joint biomechanics can all play a role in the development of koa. poor joint biomechanics is thought to play a role in primary progressive koa, in which the disease steadily worsens over time [5]. koa is commonly associated with clinical symptoms such as slowonset knee pain that worsens with movement, knee stiffness and edoema, discomfort after long periods of sitting or sleeping, and growing pain with time. foot characteristics and mechanics, such as static foot posture (e.g., flatfoot or high arch) and dynamic foot function (e.g., how the foot moves when walking or running), may contribute to musculoskeletal diseases in the lower limbs. however, the specific relationships between foot features, foot mechanics, and the development or progression of koa have not been extensively studied and are not well understood. the research has two primary goals. the study intended to analyse the variations in foot features between persons with koa and those without the disease. by comparing the foot features of these two groups, the researchers attempted to understand if specific foot traits are more widespread or distinct in persons with koa. furthermore, the study focused primarily on investigating midfoot abnormalities in persons with advanced koa and tried to acquire a better understanding of how midfoot deformities may be associated to the progression or severity of koa. 1.2 literature review foot posture has a substantial impact on the development of lower limb musculoskeletal problems because it effects mechanical alignment and dynamic function. foot abnormalities can result from a variety of clinical disorders, including osteoarthritis and rheumatoid arthritis. these disorders not only have an impact on one's quality of life, but they can also cause immobilisation and functional limits. the most common foot deformity related with koa is flatfoot. flatfoot is defined as a collapsed or low arch of the foot, which might change the biomechanics of the lower limb and contribute to the development or symptoms of koa [6-8]. footprint measurements, such as the arch index (ai) and the chippaux-smirak index (csi), are often used to assess foot alignment. these measurements are used because they are simple and easy to calculate, and they give a means to categorise foot arches, particularly those with lower arches [9]. these measurements can help physicians and researchers categorise people based on their foot arch types and investigate the link between foot alignment and other foot-related illnesses or pathologies p. levinger et al [10] significant differences in the arch index were detected between a control group and people with koa. this implies that foot posture, as measured by the arch index, differs between these two populations. furthermore, an increased ai has been identified as a contributing factor to lower muscle strength in the hamstring muscles on both the same side (ipsilateral) and the opposite side (contralateral), as well as in the contralateral quadriceps muscles in koa patients with flatfoot deformity in their dominant leg [11]. this suggests that flatfeet deformity, as evidenced by an elevated arch index, ruba musaid al-khwarizmi engineering journal, vol. 20, no.2, p.p. 113(2024) 75 may have ramifications for muscular strength in persons with koa. there is a substantial relationship between the severity of the flattening of the foot arch and the symptoms of koa, as measured by clarke's angle (ca). this implies that the degree of flattening of the foot arch is directly associated to the prevalence and severity of symptoms reported by patients with koa [12]. daman k. jha et al [13] found that hallux valgus deformities, pes planus (flatfoot), and hindfoot varus were the most prevalent foot deformities associated with koa. the study indicates that these specific foot abnormalities are typically reported in persons with koa. in a study conducted by h. guler et al [6], foot abnormalities were analysed in 115 women with koa, and there was a significant link between the existence of foot deformities and greater degrees of impairment in women with koa. this indicates that the presence of foot abnormalities is connected with higher impairment in women affected with koa. a. priya et al [14] indicate that the staheli index (sti) and csi are more sensitive in diagnosing flatfoot in teenagers than the ca. the enhanced sensitivity of the sti and csi demonstrates their efficacy in reliably identifying patients with flatfoot in this age range. furthermore, the csi and sti have a positive association, indicating that they measure comparable characteristics of foot arch deformity. individuals with koa may develop a variety of foot malformations, including rearfoot, midfoot, and hindfoot deformities. hindfoot varus deformity, in particular, has been discovered in around 30% of patients with end-stage varus koa, demonstrating a considerable relationship between these two disorders [15, 16]. furthermore, data suggests that patients with koa may have altered rearfoot posture, particularly pronation, as a compensatory response to the knee's varus alignment. the foot can keep its plantigrade posture, which is necessary for walking and weight distribution, according to this compensating mechanism [17]. kuryliszyn-moskal discovered that the impact of rheumatoid arthritis (ra) and oa on women's weisflog's index (w) index is more significant compared to the control group. also, the prevalence rate of α, indicated by the angle value, was significantly higher in the ra group compared to both the oa and control groups. however, no significant differences were observed between the groups in terms of ca or the prevalence rate of longitudinal arch pathology based on the angle value [18]. in older individuals, having a flat foot (high ai) is associated with recurring knee pain and the degeneration of cartilage in the medial tibiofemoral joint. this indicates that the shape of the foot, specifically a planus foot or flat arch, is linked to both the presence of chronic knee discomfort and the deterioration of the cartilage in the inner part of the knee joint [7]. c. p. ojukwu et al examined the ai of pregnant women and found that those with low foot arches, indicative of pes planus or flat feet, experienced more frequent foot and knee discomfort [19]. additionally, s. m. shariff et al [20] revealed a significant correlation between different categories of body mass index (bmi) and foot arches, as assessed by five different footprint parameters. the results, obtained through csi, ca, ai, and sti, indicated that increased bmi does have an impact on foot arches. therefore, individuals who are overweight or obese should take measures to effectively manage their body weight and utilize appropriate footwear to prevent foot disorders. according to m. adamczyk et al [21], there is an inverse relationship between the w index and increasing body mass index (bmi). in other words, as bmi rises, the w tends to decrease. subsequent research [22] suggests that different assessment methods for foot arch disorders may yield varying results and levels of agreement. ca, in particular, may have limitations in accurately detecting flat feet compared to the csi index. however, as bmi increases, the discrepancy between these measurements becomes less pronounced, implying a potential association between bmi and the accuracy of foot arch evaluations. the aforementioned literature reveals the planter footprint is a typical technique for assessing the integrity of the foot arches. numerous scientific study articles have been published regarding the significance of oa and flatfoot, although a few findings have been proven to be contentious by others. researchers and physicians using ai to measure the arches of the foot are unable to capture the degree of foot deformation. there is no considerable study to illustrate the classification of flat and high arch feet. these obstacles are met by the development of computer techniques based on image processing to enable better detection of variations in foot morphology, allowing the expert to make a prompt diagnosis. to address this issue and fill gaps, the current study aims to use a tool capable of measuring plantar foot indices to ruba musaid al-khwarizmi engineering journal, vol. 20, no.2, p.p. 113(2024) 76 identify changes in foot morphology in individuals with koa using simple and useful parameters, and to analyse the relationships between these changes and the grade of oa affected knee. 2. materials and methods 2.1 participants the inclusion criteria were as follows: age range > 55 years, healthy and physically active, without a history of major lower-extremity or lumbar-region injuries or surgery (for the control group) and subjects with koa for the case group. seventyeight subjects (46 np and 32 subjects with koa) participated in this study; the demographic characteristics of all participants are presented in table 1, which displays the average values of age, height, weight, and bmi of non-pathological (np) and koa subjects who participated in this study. the average age and bmi of all participants were 61.4 and 63.5 years and 32 and 32.6 kg/m2, for np and oa groups, respectively. this means that participants were consistent in their group age, and they both had overweight where the normal bmi ranges from 18.5 to 25 kg/m2 [100]. age, weight, and bmi were compared between the np and oa groups using the t-test. the height and weight of np and oa subjects were found to vary significantly (p<0.05) as shown in table 1. the np subjects were found to be taller and heavier than the oa subjects. no significant differences between groups on their age. also, there was a significant difference in bmi between the two groups. kellergen's classification for grading the koa of each subject is illustrated in table 1. the koa subjects who participated in this study are classified as severe koa. the nrs rating for pain in koa participants is presented in table 1, this revealed high pain in patients with severe koa. table 1, participants’ demographic characteristics. n: number of subjects. 2.2 experimental protocol 1. knee pain assessment: participants were surveyed using a questionnaire to determine if they experienced any pain in their knees. they were specifically asked if they had pain in either the right, left, or both knees. 2. age, gender, and bmi evaluation: the study collected data on age, gender, and bmi from all participants. bmi was calculated by dividing the weight in kilograms by the square of the height in meters. to ensure accuracy, participants were weighed without shoes and heavy clothing using a balance beam scale. 3. safe staircase setup: a staircase was positioned alongside a podoscope device to facilitate the safe ascent of participants, as depicted in fig. 1 the purpose of this arrangement was to ensure the safety and comfort of individuals during their interaction with the device. 4. ethical approval documentation: the study involved obtaining ethical approval from the relevant authorities. the required ethical approval documents were completed and submitted, ensuring compliance with ethical guidelines and regulations regarding human participant research. these materials described the study's design, protocols, possible risks and benefits, informed consent process, and protection of participant confidentiality and privacy. the ethical approval procedure was designed to guarantee that the study parameters np (n =46) oa (n =32) p value age (year) 61.4 ±4.8 63.5±5 0.569 height (cm) 174.6±4.3 163.1±5.5 0.00 body weight (kg) 98.5±18.9 86.8±10.7 0.009 body mass index (kg/m2) 32±5.5 32.6±3.9 0.00 kl grade na grade (3), n=17 grade (4), n=15 nrs rate na nrs rate (5), n=7 nrs rate (6), n=10 nrs rate (7), n=2 nrs rate (8), n=5 nrs rate (9), n=6 nrs rate (10), n=2 ruba musaid al-khwarizmi engineering journal, vol. 20, no.2, p.p. 113(2024) 77 followed ethical standards and protected the rights and well-being of the persons participating. fig. 1. podoscope with a small staircase. 5. participants' feet were uniformly wetted using water and then dried meticulously using a towel. subsequently, participants were instructed to stand upright and face forward while positioning their feet on the podoscope instrument. a podoscope instrument was used to assess the plantar footprint and enable accurate estimation of clinical indexes of foot deformities based on image processing techniques [23]. after a few attempts to ensure proper positioning, images captured by the camera and calculations for six distinct footprint parameters, namely ai, csi, sti, w, ca, and α, were successfully employed to determine foot morphology as shown in fig. 2. 6. fig. 2. podoscope structure with a protocol of the test [23]. 2.3 numerical rating scale (nrs) for pain the numeric rating scale (nrs) is a commonly utilized self-report measure for assessing pain intensity. it is widely used due to its simplicity (requiring no specialized equipment) and the preference of healthcare professionals for its 0 to 10 metric, which allows for quantifying patient discomfort. individuals are typically asked to rate their pain intensity on a scale from 0 to 10, with 0 representing no pain and 10 representing the strongest or worst pain imaginable [24].in this study, the nrs was used to classify the level of pain experienced by each participant with koa. 2.4 receiver operating characteristic (roc) curve the receiver operating characteristic (roc) curve is a graphical representation that assesses the diagnostic accuracy of a test. in this work, the roc curves for three gold parameters, ai, csi, and sti, were shown, and they showed good accuracy in recognising the presence or absence of a certain condition. the roc curve is often presented in the top left triangle above the reference line, indicating no discriminating ability (y=x line). the area under the roc curve (auc) is a quantitative measure of the test's ability to discriminate. an auc of 0.5 indicates no discrimination, while an auc of 1.0 indicates perfect discrimination [25]. 2.5 statistical analysis statistical analysis was done in the statistical packages for social science (spss, version 26, ibm). the descriptive statistics were computed and provided as mean ± standard deviation for tables and as mean ± standard error of the mean for figures of the np and koa groups. for ai, csi, sti, age, bmi, height and ca parameters: parametric tests were used to identify the significant differences between the control and koa groups. the normality of the data distribution was assessed by using the kolmogorov-smirnov test with lilliefors correction and the shapiro-wilk test (p ≥ 0.05). the analysed quantitative variables did exhibit normality of distribution. the parametric t-test was applied in two groups to compare quantitative variables. for the w index and α angle: non-parametric tests were used to identify the significant differences between the control and koa groups. the normality of the data distribution was assessed by mann-whitney between the two ruba musaid al-khwarizmi engineering journal, vol. 20, no.2, p.p. 113(2024) 78 groups. all results were considered to be statistically significant (p < 0.05). the results of ai, csi and sti were compared with the clinical diagnosis of the foot as a gold standard and displayed on a receiver operating characteristic (roc) curve. also, the roc area under the curve (auc) was computed. the correlation between koa foot parameters was calculated using pearson's correlation coefficient. 3. results 3.1 foot characteristic the associations between these variables were looked at in terms of the effect of koa on foot morphology, and the results are shown in table 2. koa foot group had significantly higher ai, csi and st than usual, as shown in fig. 3 (a,b,c,e), ai (0.29± 0.018, vs. 0.238 ± 0.017.), csi(0.55.4±0.5., vs.0.39.09±0.5), sti (0.77±0.7 vs. 0.58 ± 0.9), and the w index reduced significantly in oa compared to the np group (2.7 ±0.25vs. 2.9 ± 0.20), whereas the ca and α did not show a significant difference between two groups as shown in fig. 3 (d,f), respectively. table 2, differences in foot posture measurements between the two groups. ai= arch index; csi= chippaux-smirak index; sti= staheli arch index; w= weisflog's index; ca= clarke’s angle; α= hallux valgus angle;n=number of subjects. (a) (b) (c) (d) 0 10 20 30 40 50 60 70 total c si oa np measure np (n = 46) koa (n = 32) p-value ai (0.238 ± 0.017) (0.29± 0.018) p = 0.00 csi (0.39 ± 0.5) (0.55± 0.5) p = 0.00 sti (0.58 ± 0.9) (0.77±0.7) p = 0.00 w (2.9 ± 0.20) (2.7 ±0.25) p = 0.00 ca (31.2± 2.199) (30.27 ± 2.7) p = 0.109 α (14 ±2.7) (13 ± 1.8) p = 0.50 ruba musaid al-khwarizmi engineering journal, vol. 20, no.2, p.p. 113(2024) 79 (e) (f) fig. 2. relation between np and koa groups (a) ai= arch index; (b) csi= chippaux-smirak index ; (c) sti= staheli arch index; (d) ca= clarke’s angle; (e) w= wejsflog's index; (f) α= hallux valgus angle. pearson correlation between the parameters of koa was calculated. as shown in table 3, among the six parameters analyzed, ai, csi and sit showed the strongest correlation between them. rearfoot, midfoot and hindfoot areas were calculated for both groups. midfoot deformities have a significant difference in the subject with the oa group (p=0.00) rather than other areas of the foot as shown in table 4. the results of ai, csi and sti of the koa group were compared with a clinical diagnosis of foot deformities as a gold standard and displayed on a receiver operating characteristic (roc) curve. the methodology used in this study followed that described by chen et al [26]. the roc curves for the methods of footprint analysis are displayed in fig. 4. the area under the curve (auc) shows that ai had high accuracy for predicting koa (auc 0.74), followed by the csi (auc 0.7) and the si (auc 0.64). the auc of the ai and csi have a significant effect from that of the sti as shown in table 5. table 3, significant correlation of parameters in the koa group. parameters r-value p-value ai&sti 0.35 0.04* csi&sti 0.445 0.011* csi&ai 0.767 0.00* * correlation is significant at the 0.05 level (2-tail). ai= arch index; csi= chippaux-smirak index; sti= staheli arch index; w= weisflog's index; ca= clarke’s angle; α= hallux valgus angle. table 4, participants' foot part demographic characteristics. *significant at the 0.05 level table 5, the area under the curve. fig 3.roc curve between gold standard parameters (ai, csi, and sti). to assess the foot deformation based on pain and oa grade, the correlation was calculated part of foot np koa p value rearfoot 605.7±39.6 604.25±31.2 0.85 midfoot 242.4±32.2 333.5±28.6 0.00* hindfoot 430±37.1 433.3±35.2 1.66 koa parameters the area under the curve p value ai 0.714 *0.04 csi 0.7 *0.04 sti 0.443 0.50 ruba musaid al-khwarizmi engineering journal, vol. 20, no.2, p.p. 113(2024) 80 respectively. table 6 shows that pain and oa grade have a significant correlation between them with (r=0.9), also ai and csi have a significant correlation with oa grade with (p=0.029) and (p=0.04) respectively. in contrast, there was no correlation between foot deformation and pain in the knee. table 5, the correlation between pain and oa grade on foot morphology. koa parameters pain oa grad r-value p-value r-value p-value ai 0.3 0.6 0.4 0.029* csi 0.2 0.1 0.4 0.04* si -0.12 0.53 -0.118 0.519 w 0.299 0.9 0.155 0.039* ca -0.09 0.6 -0.149 0.04* α 0.29 0.1 0.15 0.03* pain 1 0.9** 0.00 oa grade 0.9** 0.00 1 *significant at the 0.05 level.** significant at the 0.01 level. ai= arch index; csi= chippaux-smirak index; sti= staheli arch index; w= weisflog's index; ca= clarke’s angle; α= hallux valgus angle. 4. discussion this study assessed the association between koa and foot deformities. additionally, more severe flatfoot was significantly associated with a greater risk of severe oa symptoms. six distinct footprint parameters, namely ai, csi, sti, w, ca, and α, were successfully employed to determine foot morphology. the key findings of the study were as follows: (i) the increase of ai was significant with oa symptoms. (ii) the high csi and sti were associated with a significantly increased risk of having oa. (iii) no significant differences were captured in the α and ca between the np and koa groups. (iv) transverse arch was significantly different between the two groups this was identified by the w index. the recent findings of this study have significant implications for the management and treatment of koa. when deciding on conservative treatment options like as surgery or orthotics, it is critical to consider the individual's foot morphology. healthcare providers can personalise treatment approaches to patients with koa by taking into account the particular qualities of their foot. understanding the association between foot shape and koa can result in more personalised and successful treatment regimens. a prior study shown that koa had a stronger affect on the back [27] and hindfoot [13] demonstrated changes in subjects with oahowever, to our knowledge, the particular influence of koa on the midfoot has not been extensively identified. one significant finding from this study is that koa has a greater impact on the anatomy of the midfoot. this research emphasises the need of identifying and correcting midfoot alterations in persons with koa, which may have repercussions for their overall biomechanics and functional outcomes. recognising the effect of koa on midfoot morphology allows healthcare providers to plan tailored therapies that address these particular abnormalities. interventions for improving midfoot stability and alignment may include bespoke orthotic devices, footwear adjustments, or particular exercises. by combining foot morphology assessments into koa management, healthcare professionals may optimise treatment regimens and perhaps enhance patient results. table 1 shows that there was no significant difference in average age between those with symptomatic koa (63.5±5) and those with np (61.4 ±4.8). the age category between (55-80) was chosen. the basis for this decision is based on past study linked to this, symptomatic koa increasing with each decade of life, with the annual incidence of koa being highest between the ages of 55 and 64 [28]. this finding further justifies the chosen age range for the study. ai has developed as a reliable and effective way for reliably computing foot characteristics from static footprints [29]. this technique has substantial therapeutic relevance, especially in the evaluation of persons suffering from koa [10]. notably, a comprehensive investigation done in this area found significant differences in foot features between the koa group and the normal ruba musaid al-khwarizmi engineering journal, vol. 20, no.2, p.p. 7385(2024) 81 population (np) group. these disparities were substantiated by the mean and standard deviation of ai values, which were determined to be (0.238 ± 0.017) and (0.29 ± 0.018), respectively, and demonstrated statistical significance with a p-value lower than 0.05. specifically, individuals with koa displayed a pronounced tendency towards longitudinal flattening and deformity in their feet when compared to the feet of those in the normal population. this observation can be attributed to excessive midfoot loading, which potentially leads to heightened compressive stresses on the dorsal aspect of the foot [30]. this study sought to acquire a better knowledge of the interaction between ai and midfoot loads, as well as their influence on koa, by analysing the related deformities and their exact locations. the current study conducted computations for the rearfoot, midfoot, and hindfoot regions to identify the major regions of foot deformation in individuals with koa. the analysis aimed to determine the specific locations where these deformations occurred as a response to the koa condition. additionally, this study tried to agree or disagree with a prior study that connected greater ai values to more midfoot [31] and peak pressure at the midfoot [32]. table 4 indicated that there was no significant difference observed between the rearfoot and hindfoot regions in either the koa or np groups. thus, these regions cannot be utilized to distinguish between the two groups. however, the midfoot region exhibited a significant difference (p=0.00), making it the reference landmark for identifying foot deformations in individuals with koa. this finding aligns with the previous studies mentioned earlier regarding midfoot loading [31] and pressure [32]. the association between increased midfoot loading and two additional parameters, namely csi and sti, is of considerable importance. the study findings demonstrated a significant difference (p=0.00*) in csi values between the koa and np groups. the np group had csi values of (0.39 ± 0.5), whereas the koa group had csi values of (0.55 ± 0.5). this discrepancy can be attributed to the csi (midfoot/forefoot) rule, indicating that the midfoot morphology of individuals with koa experienced notable changes, resulting in higher csi values. in contrast, the np group, which did not experience knee discomfort, displayed no significant alterations in midfoot morphology, as evidenced by csi values remaining within the normal range of 0.25 to 0.45. likewise, the sti index exhibited a similar trend to csi, calculated as the ratio of midfoot to hindfoot. it is directly proportional to the midfoot condition. the study also observed a significant difference (p=0.00*) in sti values between the koa and np groups. the np group had mean sti values of (0.58 ± 0.9), while the koa group had mean sti values of (0.77 ± 0.7). the np group fell within the normal sti range of 0.50 to 0.70, indicating a normal midfoot condition. conversely, the koa group displayed higher sti values, suggesting abnormalities in the midfoot region. so, these three parameters served as a gold standard for distinguishing between np and oa groups. foot deformities, particularly hallux valgus and pes planus (flat feet), are frequently observed in individuals with koa. these deformities contribute to abnormal excessive stress on the medial compartment of the knee joint and medial rotation of the tibia [6, 33]. one potential compensatory motion or posture is subtalar joint pronation, which generates a valgus force and leads to the development of pes planus and hallux valgus [34]. hallux valgus (α) is a foot deformity characterized by abnormal angulation, rotation, and lateral deviation of the first metatarsophalangeal joint of the big toe [35]. the typical range of this angle is 0-9 degrees, and values exceeding 9 degrees indicate the presence of hallux valgus [18]. in the present study, participants in the np group, who were aged up to 50 years, exhibited a higher range of hallux valgus angle (14 ± 2.7) due to age-related changes. as a result, both the np and koa groups had higher indices, and there were no significant differences between the two groups when considering the influence of age. these findings align with the predictions made by pita-fernandez et al [36], who reported a higher prevalence of hallux valgus with increasing age, with 38% of the individuals in their study exhibiting this deformity. similarly, ca was used to assess foot morphology. in the present study, the mean ca value in koa patients was approximately 30.27 ± 2.7, while the mean ca value in the np group was 31.2 ± 2.199, and the difference was not statistically significant (p = 0.109). the evaluation of longitudinal arch pathology based on ca also showed no significant differences between the two groups. these findings are consistent with a previous study [37]. the current study revealed that the prevalence of hallux valgus increases with age, but there were no significant differences in hallux valgus angle ruba musaid al-khwarizmi engineering journal, vol. 20, no.2, p.p. 7385(2024) 82 and longitudinal arch pathology between the koa and np groups when accounting for age-related changes. therefore, these angles cannot be used as fundamental diagnostic parameters to distinguish between np and those with koa. additionally, the presence of foot deformity based on these angles cannot reliably predict the occurrence of koa. the w index is a widely used indicator for evaluating the transverse arch of the foot [38]. in the present study, significant differences (p=0.00) were observed in the transverse arch between the koa and control groups. this suggests that individuals with koa display alterations not only in the longitudinal arch (as measured by ai, csi, and sti) but also in the transverse arch. these findings are consistent with another study that reported significant differences in the w index values between a control group and individuals with koa [18]. the koa group exhibited severe oa grades and reported high levels of knee pain, which were confirmed by a consultant using kellgren's classification for grading koa and a numeric rating scale (nrs) for pain assessment, as shown in table 1, respectively. interestingly, no significant impact of knee pain on foot deformities was observed. the presence of severe koa was the primary factor contributing to the high levels of knee pain, as demonstrated by the strong correlation (r=0.9, p=0.00), as shown in table 6. however, it remains unknown whether foot deformities directly cause knee pain. these findings are consistent with a previous study [39], which suggests that symptomatic koa itself leads to knee pain and functional impairment [40]. moreover, a notable association was found between the grade of koa and both ai and csi, as presented in table 6. this correlation finding aligns with the outcomes of the roc curve analysis, which revealed significant area under the curve (auc) values for ai and csi with oa grade as shown in fig. 4 and table 5. these results indicate that individuals with more severe koa tend to have greater foot deformities, as indicated by higher ai and csi values. hence, when assessing the severity of koa, it is crucial to consider the existence of foot deformities. it is worth noting that further research is needed to fully understand the relationship between koa, foot morphology, and the effectiveness of different treatments of koa approaches. however, these recent findings shed light on an important aspect of foot management that had not been welldocumented previously, paving the way for future investigations and potentially enhancing the care provided to individuals with koa. 5. conclusion  the prevalence of foot deformities is significantly higher in koa.  assessing the association between koa features and foot characteristics may aid with accurate diagnosis and koa treatment.  koa was most often related to mid-foot abnormalities.  among the six parameters that were used to identify changes in foot morphology, ai, csi, sti and weisflog’s index acted as indicators for the incidence of foot deformities in the koa group. however, there is no significant difference in ca and α angles between koa and foot deformity.  ai and csi were linked to koa grade. this association matches the roc curve study, which showed substantial auc values for ai and csi about oa grade. 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(2024) 73-85، صفحة 2، العدد20مجلة الخوارزمي الهندسية المجلد سارة مرتضى سعدون 85 القدم للمرضى المصابين بسوفان العظام في مفصل الركبةتقييم تشوهات ***وليد عبد الحسن عبد الواحد ،اسيل محمد عبد الحسين** ،ربى مساعد طه* العراق، بغداد ، جامعة النهرين ،كلية الهندسة ، هندسة الطب الحياتي قسم **،* العراق ،بغداد ،مدينة الطب *** st.ruba.m.taha@ced.nahrainuniv.edu.iqااللكتروني:*البريد aseel.m.ali@nahrainuniv.edu.iq *البريد االلكتروني:* board.education-waleedbgh@arab*البريد االلكتروني: ** المستخلص مورفولوجيا القدم بشكل شائع لتقييم تشوهات القدم. القدم ضرورية للحفاظ على األداء الميكانيكي الحيوي لألطراف السفلية. سوفان تستخدم تقنيات تقييم يعانون كان الهدف الرئيسي من هذه الدراسة هو التحقيق في انتشار تشوه القدم في المرضى الذين .الركبة هي حالة مرضية يمكن أن تؤدي إلى تشوهات القدم و الهدف اآلخر هو تحديد تأثير األلم وشدة سوفان العظام على التغيرات المورفولوجية للقدم الخاص بمرضى سوفان العظام في .من سوفان العظام في الركبة ركبة.جهاز بودوسكوب مصابين بسوفان العظام في ال 32شخص غير مصابين, 46ثمانية وسبعون مشارك ساهم في هذا البحث وقسموا الى قسمين, .الركبة :المطور يعطي النتائج بشكل اوتوماتيكي لتشخيص تشوهات القدم عن طريق المؤشرات االتية arch index (ai), chippaux-smirak index (csi), staheli index (si), wejsflog's index, clarke’s angle (ca) and hallux valgus angle (α). غيرات المتعلقة بالقدم بطريقة مباشرة بالتهاب مفاصل الركبة. على وجه الخصوص، كان و أولئك الذين أصيبوا بالتهاب مفاصل الركبة تم ربط العديد من المت قيم أعلى بكثيرللمؤشرات مقارنة بمن لم يصابوا بهذا المرض arch index (0.29±0.018; p=0.00), chippaux-smirak index (0.55±0.5; p=0.00), staheli index (0.77±0.7; p=0.00), and weisflog's index (2.7±0.25; p=0.00(. ( على التوالي. كانت هناك أيًضا ارتباطات مهمة 1.8±13( و)2.7±30.27عالوة على ذلك، أظهرت زاوية كالرك وزاوية إبهام القدم األروح قيًما عالية تبلغ ) ;chippaux-smirak (0.767 ومؤشر arch كان هناك، على سبيل المثال، ارتباط إيجابي كبير بين مؤشر موجودة داخل مجموعة التهاب مفاصل الركبة. p=0.00)ومؤشر ، arch ومؤشر staheli (r=0.35; p=0.04 )ومؤشر ، chippaux-smirak ومؤشر staheli بارتباط يساوي . (r=0.44; p=0.01)من حيث تشوهات القدم، كان منتصف القدم (333.528.6; p=0.00) أكثر أهمية من مقدمة القدم (604.2531.2; p=0.85) ومؤخر -chippaux ومؤشر arch ، تم ربط كل من مؤشر(r = 0.4; p = 0.04) و (r = 0.4; p = 0.02) مع قيم االرتباط .(p=1.66 ;433.335.2) القدم smirak الجهاز اوضحت اختالف واضح بين االشخاص المصابين بسوفان العظام في الركبة النتائج المخرجة من .بشكل كبير مع شدة التهاب مفاصل الركبة :ةوالغير مصابين.اكثر االصابات بلتشوه كانت واضحة جدا في المؤشرات التالي ai, csi, si, and w index. الشخاص المصابيين اضافة لذلك النتائج بينت تشوه القدم في المنطقة الوسطى هو اكثر من بقية اجزاء القدم الصحاب ا تشوهات القدم واضحة الصحاب مرض سوفان العظام في الركبة حيث تتضمن تشوهات في االقواس الطولية والعرضية اضافة .بسوفان العظام في الركبة كبة.قد يستهدف مقدمو الرعاية لذلك,انحراف ابهام القدم.لذلك وجب اخذ بعين االعتبر هذه التشوهات عند تشخيص االشخاص المصابين بسوفان العظام في الر األحذية الصحية تأثيرات سوفان العظام في الركبة على مورفولوجيا منتصف القدم بعالجات مركزة. وقد تعمل أجهزة تقويم العظام المخصصة وتعديالت ج سوفان العظام في الركبة ونتائج المرضى من والتدريبات الخاصة على تعزيز استقرار منتصف القدم . ايضا ويمكن ألخصائيي الرعاية الصحية تحسين عال .خالل تقييم مورفولوجيا القدم mailto:waleedbgh@arab-board.education this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 19, no. 2, june, (2023) p. p. 8294 a review of the stereo lithography 3d printing process and the effect of parameters on quality tiba raed mhmood* nazar kais al-karkhi** *,**department of automated manufacturing engineering/ al-khwarizmi college of engineering/ university of baghdad/ baghdad/ iraq *email: tiba.abd2204m@kecbu.uobaghdad.edu.iq **email: nazarkais@kecbu.uobaghdad.edu.iq (received 10 november 2022; accepted 16 april 2023) https://doi.org/10.22153/kej.2023.04.003 abstract stereo lithography (sla) three-dimensional (3d) printing process is a type of additive manufacturing techniques that uses digital models from computer-aided design to automatically produce customized 3d objects. around 30 years, it has been widely utilized in the manufacturing, design, engineering, industrial sectors and its applications in dentistry for manufacturing prosthodontics are very important. the stereo lithography technology is highly regarded because it can produce items with excellent precision especially when selecting the best process parameters. this review article offers a useful and scientific summary of sla three-dimensional printing technology and its brief history. the specific type of 3d printers which is sla type based on light curing resin and material overview is also presented. moreover, the survey was conducted to gain substantial knowledge of the various advantages and disadvantages of sla 3d printing. according to this study, a summary has been specified on the accuracy of sla 3d printers and various factors that affected its accuracy and dimension measurement namely layer thickness, normal exposure time, bottom or top exposure time, post processing and room temperature. the majority of works in the literatures conducted till date are on improving the physical part attributes like dimensional accuracy and surface roughness but the improving of the mechanical properties have received less attention and need more focusing in the future works. keywords: additive manufacturing, bottom or top exposure time, 3d printing, normal exposure time, resin, stereo lithography, uv. 1. introduction additive manufacturing (am) technologies are generally called three-dimensional (3d) rapid prototyping printing processes. based on computer-aided design (cad) digital model, a group of techniques that permit the layer by layer construction of complex 3d shapes out of a variety of standardized materials, including solid, liquid, and powder [1, 2]. the flexible design of such a process increases its capacity for manufacturing a wide range of functional products [3]. additionally, it can quickly produce one-off and small-batch components, fresh samples, and goods with complicated shapes, molds, and models [4]. stereo lithography is recognized as the first commercial rapid prototyping device for what is commonly known today as 3d printing. the 1970s saw the introduction of the first significant stereo lithography (now popularly known as sla) am work. swainson [5] offered a patent for a technique that makes use of two intersecting radiation beams to photochemically cross-link or degrade polymers to create 3d structures. then herbert [6] presented a method for layer-by-layer construction of solid things using photosensitive polymers. however, the majority of individuals consider that charles hull's [7] work marked the beginning of modern stereo lithography. his theory (figure 1) proposes that photosensitive liquid materials that ultraviolet mailto:tiba.abd2204m@kecbu.uobaghdad.edu.iq mailto:nazarkais@kecbu.uobaghdad.edu.iq https://doi.org/10.22153/kej.2023.04.003 tiba raed mhmood al-khwarizmi engineering journal, vol. 19, no. 2, p.p. 92104 (2023) 83 (uv) light can cure are used to layer by layer create 3d creations [1]. hull invented a 3d printing technology and obtained a patent for stereo lithography (sla). hull then formed the company 3d systems, which presented the first 3d printer (sla-250) to be sold commercially, in 1988 [4, 8]. today, over 75% of dental applications for 3d printing employ light-curing technology, and lightcuring resins are often used as fillers and restorative materials in dentistry. the global standard for dental prostheses is moving toward digital dental medical technology [9]. the use of sla 3d printing in dentistry can aid in the provision of more inexpensive dental equipment. since stereo lithography is adaptable enough to produce several very complex 3d objects with great precision and a low costs. an increasing number of materials have been created by sla for a wide variety of applications, including soft robotic actuators, sensors, microfluidics devices and energy storage components [1, 10]. medical implants are the most important applications of sla such as dental prostheses [11]. this review discusses the stereo lithography process including its technology, material overview, advantages, disadvantages, sla printer parameters. the accuracy of sla printing process and the factors affecting will be discussed in detail. fig. 1. stereo lithography setup [1]. 2. stereo lithography (sla) 3d printing technology stereo lithography has made significant progress, and many methodologies for stereo lithography systems have been developed. huang et al. [1] categorized the described technologies into four generations, with hull's work being the first generation stereo lithography, which creates 3d items by scanning a laser beam over liquid materials. to overcome the limitations of poor efficiency, the second generation technique was used, also known as projection stereo lithography, uses photo mask technology to cure each layer concurrently. tumbleston et al. [12] developed third generation stereo lithography in 2015. they developed a continuous liquid interface production (clip) technology that allows for far faster print speeds than earlier approaches, allowing them to make components in minutes rather than hours. recently, a volumetric stereo lithography technique was developed, also regarded as the fourth generation. [1]. an extrudable thermoplastic filament is substituted by a vat of a liquid uv curable photopolymer in the somewhat more sophisticated additive manufacturing technique known as sla. at the moment, sla method is the primary foundation for big industrial photocuring 3d printing machines [13]. the sla three dimension (3d) printer uses an ultraviolet laser beam to solidify an acrylic photopolymer at a specific previously predetermined spot [14]. figure (2) shows the stereo lithography apparatus which consists of the following components: (a) low uv radiation laser source, (b) when the laser beam hardens bottom layers to top layers during manufacturing, an elevator raises the construction platform (illustrated in g), (c) for the purpose of treating the liquid photopolymer's surface, lenses focus an intense laser beam from a uv source, (d) the beam is redirected by the x-y scanning mirror so that it descends vertically into the liquid photopolymer instead of traveling horizontally (the deflection of the mirror depends on the desired 3d model), (e) photosensitive polymers harden when they come into touch with the laser beam, leaving untreated polymers liquid, (f) a big container called a "vat" that holds photosensitive liquid, (g) build platform is each layer of photosensitive polymers represents a cross section of the final 3d object and is created layer-by-layer from bottom to top, (h) liquid photopolymer, (i) layered part is a combination of solidified photopolymer layers, (j) the sweeper is recoats the stacked part's surface with a liquid photopolymer resin as the build platform (in g) descends after the solidification of each layer, (k,l) the sweeper moves to the right and left (in k) while the construction platform moves up and down (in l) [15]. tiba raed mhmood al-khwarizmi engineering journal, vol. 19, no. 2, p.p. 92104 (2023) 84 fig. 2. stereo lithography apparatus. [15]ز typically, the liquid resin is scanned by the laser beam employed by sla machines, which causes it to harden. usually, the laser beam is visible from the top above the resin tank. when the platform is lowered into resin, the resin's surface is covered by a thick layer of the platform's surface. after the layer of resin has dried and solidified, the platform falls a certain distance. layer by layer, the solidification procedure is performed to produce a solid 3d part. the laser beam then fills up a twodimensional cross section of the model by following its edges. the fabrication process of stereo lithography is shown in figure (3) [1]. the model is completely cured in a uv oven after printing in order to completely eliminate resin residues [14]. fig. 3. fabrication process of stereo lithography [1]. 3. sla material overview sla uses a variation of materials with a wide range of characteristics including soft, transparent, very stable, and even heat resistant materials [14]. photosensitive resin is the substance utilized in the photocuring process for 3d printing. the light wavelength and the method of printing would determine the photo curing procedure [13]. conventional epoxy, acrylate resins, or thermoplastic elastomers make up the majority of the materials utilized in sla. first monomers were blends of multipurpose acrylates that resulted in cross-linked resins. the low viscosity of this composition helps the liquid spread smoothly. it also has high photosensitivity, oxygen inhibition, low critical energy, controlled mechanical properties, and is relatively insensitive to changes in temperature and humidity [16]. polymers make up the majority of the 3d printing materials used in dental restorations, which replace lost teeth and tooth structure. in contrast to ceramics and metals, the chemical and physical properties of polymers are characterized by elasticity and tensile strength, which may offer the high-performance and longlasting qualities required for use as a dental restorative material [11]. the transverse strength and elastic modulus of the resin were both significantly impacted by a change in the polymerization temperature [17]. the environment to which resin is exposed affects its mechanical properties, which is why they may degrade in the oral environment in addition to being affected by their chemical composition [18]. threedimensional printing technology have created a variety of dental prosthesis using polymer materials in orthodontic treatment, including denture bases, fake teeth, temporary crowns, bridge and crown facings, and implant caps. studies have shown that polymers are used in 3d printing technology for dental applications, such as the manufacturing and intervention of implant fixtures, maxillofacial reconstruction, and metal bridges [11]. the majority of resin compositions contain inert dyes, which absorb incoming light and improve polymerization control. additional additives like surfactants and diluents or other stabilizers may be added, particularly when employing filled resins. the photo curable resins for sla all have the same essential components (figure (4)) and they are summarized as follows [19]: 1. precursors: the sla precursors are liquid molecules that, when exposed to light, may link tiba raed mhmood al-khwarizmi engineering journal, vol. 19, no. 2, p.p. 92104 (2023) 85 together (i.e., polymerize) to create a solid three-dimensional network. 2. photoinitiators (pis): it is a resin component reacts to light. when the appropriate wavelength of radiation is applied, it gets activated and prepared to initiate the curing reaction. a suitable pi must be chosen depending on the kind of precursor being employed. the kind and amount of pi employed can have a major influence on the reaction's kinetics, the amount of light used, conversion, cross-linking density, and, to a certain degree, the mechanical properties of the printed components. 3. absorbers: a light absorber, which lowers light's penetration into the resin and restricts the depth to which the resin can be cured, is another element that is important to the majority of sla processes. 4. filled resins: sla has been used to fabricate metal or ceramic materials by mixing resins with powder, printing the parts, and then sintering and debinding the printed specimens. the organic resin components are dissolved by pyrolysis during the debinding process, and the presence of a high filler content prevents defects like cracks and shrinkage from occurring. 5. additives: for slurries to have a longer shelf life and to remain stable throughout longer printing processes, rheological additives and stabilizers are required. fig. 4. materials of resin in sla [19] 4. sla 3d printing advantages and disadvantages 4.1. sla 3d printing advantages the followings are typical advantages of sla process:  sla has a well-developed, reliable printing process, and a wide range of equipment providers [13].  sla 3d printers can produce complex forms with fine details at reduced material costs when utilized in large quantities [10].  sla is adaptable to variable material selection, highest resolution, accuracy, suitable for fine details and functional prototyping and highly versatile material selection [14, 20].  sla offers great material utilization, significant cost advantages, the ability to produce specific goods at scale on demand, and relatively quick technological advancements [4, 21]. 4.2. sla 3d printing disadvantages the followings are the limitations of sla process:  resin has a limited shelf life, a short vat life, can't be heat sterilized, dirty, can cause skin sensitization, and requires expensive technology [10].  since the curing rate depends on how rapidly the laser beam moves and the size of the model affects that speed [13].  sla is presently the only photo curing three dimensional printing technique that can print big scale models, however, it has a low printing rate [13].  volume shrinking is a drawback of photocuring 3d printing, and researchers are working to eliminate it [13].  the difficulties in handling liquid resin due to its sensitivity to extensive uv light exposure and its poor mechanical qualities as a result of brittle material and curling [14]. 5. sla 3d printers parameters although sla technology has advanced quickly and attracted a lot of attention lately, it is still in the early stages of development, where several academics have discovered answers to challenging real-world issues. specificating, assessing, and managing process factors to produce precise, high-quality products has been the major focus of research efforts. because of the interrelations between variables and nonlinear relationships between final outputs and parameters, determining and optimizing process parameters is a very difficult procedure [22]. tiba raed mhmood al-khwarizmi engineering journal, vol. 19, no. 2, p.p. 92104 (2023) 86 5.1. layer thickness. thickness of each slice of the portion that builds on the preceding layer is known as the layer thickness [23]. the most suitable layer thickness setting affects sla process accuracy and performance. the building time decreases with the number of slices (and layer thickness), but accuracy decreases [24]. it has been shown that when printing samples with low layer thickness using sla technology, the accuracy and strength of the sample improves [25]. figure (5) shows the built layer thickness of a printed part. fig. 5. layer thickness in sla. 5.2. normal exposure time the normal exposure time is the precise amount of time that each layer is exposed to uv. the bending strength and chemical bonding of the printed resin were modified by the exposure duration. when exposed to uv radiation, printed items' surface roughness is also impacted, leading to two surface impacts. on the one hand, the formation of cracks is affected by the uv exposure time [26]. also, the shrinkage of the photo curable resins is affected by exposure time, which increases with the increasing of curing time leading to less accuracy [27]. 5.3. bottom or top exposure time they are the uv exposure time of the first layer thickness at the first layer fabrication between the platform and the bottom or top of the resin container figure (6). bottom or top exposure time are similar to exposure time, but only applying to the first few layers of 3d prints. the bottom or top layers of the print require more focus because they form the foundation for the whole print. the bottom or top surfaces of the exposed and curing layer bond with the previously cured layer during the manufacturing process of the free surface sla technology [28, 29]. 5.4. build orientation or angle the choice of construction angle is crucial since it influences the amount of support structures required, which may have an impact on the precision of the created components. rotation of the crown from a 90 degree build angle to a build angle of 180 degree increases the self-support surfaces and therefore decrease the number of support structures [30]. the construction angle setting has an effect on the biocompatibility, product accuracy, and material qualities [4]. figure (7) shows the orientation of 3d printing of different building angle of prosthesis. fig. 6. (a) top exposure vs. (b) bottom exposure [29] tiba raed mhmood al-khwarizmi engineering journal, vol. 19, no. 2, p.p. 92104 (2023) 87 fig. 7. different 3d printing angles [30] 5.5. post processing the performance of printed samples can be improved with proper post-processing, but it will cost more and take more time. the development of sla has been constrained by the shrinkage and distortion of resin materials. however, the postcuring procedure gets around this defect [28]. after curing, the resin item has been subjected to temperatures above curing temperature for a considerable amount of time. enhancing the elastic modulus and ultimate strength of samples can be achieved by using uv and microwave post-curing. the strength of the sample can also increase concurrently with the expansion in laser power [4, 26]. 6. effect of sla 3d printers parameters on accuracy, surface integrity and strength several researchers have attempted to enhance the dimensional accuracy and surface integrity of sla printing. one of the primary sources of inaccuracy in the sl process is the significant amount of shrinkage experienced during the postcuring phase [27]. as a result, the extended light exposure might result in a local temperature rise or local polymerization, which could lead to local stress or defects. also, according to a research by kavin kowsari et al. [31] solidified layers' breadth and height rose less linearly as exposure duration increased. dimensional accuracy in 3d printing is complex and is influenced by a number of variables, including printing technology, post processing techniques, the use of support material, and part orientation [32]. however, one of the main reasons why the prototype was not accurate enough was the resin's volume shrinkage during photopolymerization [28]. also, the model is forced to change as a result of the peeling process, which involves removing the resin from the vat's bottom. additionally, the total number of errors made at each stage of the manufacturing process, containing radiological imaging, image segmentation, the stl file generation, the stl post processing, stl file slicing for the printer control file, 3d printing, and post-processing, affects the accuracy of a functional 3d model. all these steps are strongly reliant on machine, software, ultimately and user [14]. additionally, as the stereo lithography apparatus (sla) printer's build platform descended into the resin tank to create a fresh layer, the cup could trap air and resin, resulting in structural flaws that jeopardize dimensional accuracy [33]. the sla technique's accuracy is sufficient to print items with complicated structures and small sizes [13]. however, the selection of the sla process variables to accomplish the desired results established by users is still a challenging work. the selection of the process parameters is also known as the establishment of the building strategies or building setups. the qualities of the parts produced by the sla printing machine, such as the dimensional accuracy, the surface finish, the tensile strength and the build time are often impacted by these process parameters [34]. the development of sla's accuracy has always been a fascinating case for researchers. different strategies and techniques have been employed to discover a successful solution to advance sla dimensional accuracy. jayanthi et al. [35] explored the impact of sla process parameters, as well as two alternative writing techniques (the hatch and the weave), on the curl distortion of produced components. a twin-cantilever test piece was also proposed. they came to the conclusion that the four key factors are the layer thickness, the hatch spacing, the fill cure depth, and the hatch over cure. additionally, they discovered that the weave style distortion is significantly larger than hatch type. diane a schaub et al. [36] listed the numerous stereo lithography process controls and determined that the four following factors are the most important ones that affect the end part's dimensional accuracy namely layer thickness, spot overlap, boundary over cure, and part orientation. tiba raed mhmood al-khwarizmi engineering journal, vol. 19, no. 2, p.p. 92104 (2023) 88 additionally, they examined their impact and relative importance on dimensional accuracy and came to the conclusion that layer thickness and component orientation play a substantial role in dimensional error. onuh and hon [37] tried to adjust build settings for better stereo lithography surface finish. in their experiments, the following construct characteristics were taken into account, namely, layer thickness, hatch spacing, hatch style, hatch over cure, and fill cure depth. in order to identify key process factors (layer thickness, hatch spacing, overcure, blade gap, position on the build plane), zhou et al. [23] managed an experiment utilizing specially designed components produced by sla 250. in sla dimensional accuracy. the results suggest medium layer thickness for good reduction of the dimensional error. lee et al. [38] created 140 of samples using various setup settings (layer thickness, hatch overcure, and hatch spacing), produced customized h-shaped pieces using sla 250, and measured 5 points. also, they suggested combining input parameters and output measurement data to train a neural network to forecast the dimensional accuracy of sla components. the trained network can predict the dimensional errors with a respectable level of accuracy, according to test findings on its performance. k. chockalingam et. al. [39] studies on the stereo lithography process that are listed focus on identifying the variables, namely the layer thickness, the hatch spacing, the hatch style, the hatch over cure and the fill cure depth that might influence the shrinkage rate. k. chockalingam et al. [40] made an effort to discover the process variables such as layer thickness, post-curing, and orientation that affect the strength of components created using the sl method, optimizing the parameter values, and developing an empirical regression equation between the tensile strength and their influencing parameters. the findings showed that orientation, post-curing time, and layer thickness have a significant impact on the part strength. the process parameter like orientation has the biggest impact on the part's strength. additionally, layer thickness of 0.1 mm, post curing time of 60 min, and vertical orientation are the optimum combinations of process parameters. campanelli et al. [41] tried to find the factors namely, layer thickness, hatch overcure, hatch spacing, border overcure, fill spacing and fill cure depth that lead to the best accuracy of the printed parts in the sla process and found that best accuracy was gain with low value of layer thickness. chockalingam et al. [42] studied the effect of layer thickness, orientation, and post curing time on strength of part parts made by sla. they showed that layer thickness has the major contributing factor on strength. the ideal layer thickness was 100 µm under the conditions of 60 min of post curing time and vertical construction. lee et al. for a sla 5000 type machine, layer thickness and component quality were examined by raju et al. [43]. they concluded that small layer thickness gave good mechanical qualities, high accuracy and good surface finish. guangshen xu et al. [44] carried out an experimental analysis to identify the taguchi method's ideal construction parameters like the shrinkage compensation factor of resin, the liquid surface waiting time, the exposure time and the light intensity for an integrated stereo lithography (sla) system. it was discovered that the dimensions accuracy was strongly impacted by the build settings, including the resin's shrinkage correction factor, waiting time for liquid surfaces, exposure time, and light intensity. khorasani and baseri [45] showed that layer thickness is one of the stereo lithography (sla) process factors (layer thickness, hatch overcure and hatch spacing) that has been offered as a model for optimization in order to achieve the least amount of the shrinkage and the distortion of h-shaped products. to link the input parameters to the dimensional inaccuracy of the sla-produced parts, a neural network was created. results showed less layer thickness led to minimum shrinkage with good accuracy. s. rahmati and f. ghadami [46] suggested a neural network model to identify and improve important parameters like the layer thickness, the hatch overcure, the hatch spacing, the border, the overcure, fill spacing and the fill cure depth, in order to increase accuracy and predict dimensional accuracy using different parameter values. according to the results of the study, layer thickness was the most essential factor for dimensional accuracy. multiple quality aspects of sla fast prototyping machines had been improved by raju et al. [47] by utilizing the process variables that affect the strength aspect of sla and the taguchi method-based grey relational analysis. according to the results, the layer thickness and orientation parameters have a significant impact on the component strength of sla parts other than hatch space. the optimal combinations of process parameters are 0.125 mm layer thickness and 90 orientation for tensile strength of sla parts by single quality characteristics. loflin et al. [48] evaluated the effect of sla print layer thickness on the clinical acceptability of 3d printed models. the outcomes showed that layer thickness of 100 µm was the best option. munproma and limtasiri [49] investigated tiba raed mhmood al-khwarizmi engineering journal, vol. 19, no. 2, p.p. 92104 (2023) 89 the process parameters namely, exposure resolution, layer thickness, exposure time, postcure time, up speed lift and post-cure temperature that affect part qualities namely flexural stress, hardness and part dimension. the exposure resolution had a substantial impact on the flexural strength and hardness of the 3d-printed items, whereas the post cure temperature had a large impact on the width error. ahmet cekic et al. [50] investigated the process variables like layer thickness and temperature, in stereo lithography (sla) in order to produce a smooth surface product with minimize dimensional deviations relative to the cad model. experimental studies have shown smaller layer thickness gave lower the surface roughness with good accuracy. khodaii and rahimi [51] examined how the sla process's surface roughness is affected by surface angle, hatch spacing, and postcuring time. the findings demonstrated that surface roughness increased as surface angles increased, while post-curing time had no impact. katheng et al. [52] examined the grade of polymerization of a transparent photopolymer resin specimen produced by sla for various post-polymerization times and temperatures and dimensional correctness was analyzed using an anova. lower temperatures result in enhanced accuracy and tissue surface accuracy, according to the study, which found that the polymerizing temperature had a bigger impact than the polymerizing duration, 15 minutes and 40 °c are the suggested sla polymerization parameters. n. dhanunjayarao borra [53] adjusted the printing parameters of the masked stereo lithography equipment by employing the taguchi approach to ensure the dimensional accuracy of the 3d printed components. layer thickness, orientation, and exposure time were the printing parameters that were chosen. according to the anova results, exposure duration had a significant impact on accuracy. dhanunjayarao et al. [54] examined the experimental findings regarding the dimensional accuracy of resin sla 3d printed post cured objects. the study's goal was to use design of experiments to show the inaccuracies related to dimensional accuracy as well as the interactions between the process parameters of layer thickness, exposure duration, and x-orientation. it was found that the part's variations in size and form are what cause the dimensional inaccuracies. the investigation found that layer thickness of 0.06 mm and exposure times of 3 and 5 sec with 0o and 150o x-orientation always correspond to minimal deviation. the summary of related works on effect of sla 3d printers’ parameters on accuracy, surface integrity and strength is given at table (1). table. 1, summary of related literature year and authors parameters main findings jayanthi et al. [35] the four key factors are hatch spacing, layer thickness, fill cure depth, and hatch overcure. they discovered that the weave style distortion was significantly higher than hatch type. diane a schaub et al. [36] layer thickness, spot overlap, boundary over cure, and part orientation. layer thickness and component orientation played a substantial role in dimensional error. onuh and hon [37] layer thickness, hatch spacing, hatch over, cure hatch style, and fill cure depth. the optimum build parameters proposed in this study would build parts faster, cheaper and better zhou et al. [23] layer thickness, hatch spacing, overcure, blade gap, position on the build plane. the results suggested medium layer thickness for good accuracy. lee et al. [38] layer thickness, hatch overcure, and hatch spacing. neural network could predict the dimensional errors with a respectable level of accuracy, according to test findings on its performance k. chockalingam et. al. [39] layer thickness, hatch style, hatch spacing, hatch over cure and fill cure depth. proposed a genetic algorithm (ga) to find the best process parameters and to predict process parameters for better dimensional accuracy in sla process. tiba raed mhmood al-khwarizmi engineering journal, vol. 19, no. 2, p.p. 92104 (2023) 90 k. chockalingam et al. [40] layer thickness, postcuring, and orientation. orientation had the biggest impact on the part's strength. additionally, layer thickness of 0.1 mm, post curing time of 60 min, and vertical orientation are the optimum combinations of process parameters. campanelli et al. [41] the layer thickness, the hatch spacing, the hatch overcure, the border overcure, the fill spacing and the fill cure depth. found that best accuracy was gain with low value of layer thickness. chockalingam et al. [42] the layer thickness, the orientation, the post curing time. the layer thickness had the significant contributing factor on strength. raju et al. [43] effect of the layer thickness on the part quality. they concluded that low layer thickness equivalent to 0.1 mm is optimal at which the mechanical properties and accuracy are high. guangshen xu et al. [44] the shrinkage compensation factor of resin, the liquid surface waiting time, the exposure time and light intensity. it was discovered that the dimensions accuracy was strongly impacted by the build settings, including the resin's resin shrinkage correction factor, waiting time for liquid surfaces, exposure time, and light intensity. khorasani and baseri [45] layer thickness, hatch overcure and hatch spacing. results showed less layer thickness led to minimum shrinkage with good accuracy. s. rahmati and f. ghadami [46] layer thickness, hatch overcure, hatch spacing, border, overcure, fill spacing and fill cure depth. according to the results of the study, the layer thickness was the most essential factor for dimensional accuracy. raju et al. [47] layer thickness, orientation and hatch space. the layer thickness and orientation parameters had a significant impact on the component strength of sla parts other than hatch space. loflin et al. [48] layer thickness. low value of layer thickness of 100 µm was the best option. munproma and limtasiri [49] the layer thickness, the exposure resolution, the exposure time, the post cure time, the up speed lift and the post-cure temperature. the exposure resolution had a substantial impact on the flexural strength and hardness of the 3d-printed items, whereas the post cure temperature had a large impact on the dimentional error. ahmet cekic et al. [50] layer thickness, printing temperature and print speed. smaller layer thickness gave lower the surface roughness with good accuracy. khodaii and rahimi [51] surface angle, hatch spacing, and postcuring time. the findings demonstrated that surface roughness increased as surface angles increased. katheng et al. [52] postpolymerizing times and temperatures. the polymerizing temperature had a bigger impact than the polymerizing duration, 15 minutes and 40 °c are the suggested sla polymerization parameters. n. dhanunjayarao borra [53] layer thickness, orientation, and exposure time. exposure duration had a significant impact on accuracy. dhanunjayarao et al. [54] layer thickness, exposure duration, and x-orientation the investigation found that layer thickness of 0.06 mm and exposure times of 3 and 5 sec with 0o and 150o x-orientation always correspond to minimal deviation for all output metrics. tiba raed mhmood al-khwarizmi engineering journal, vol. 19, no. 2, p.p. 92104 (2023) 91 7. conclusion this paper's objective was to review the current state of stereolithography 3d printing process and the effect of it parameters on part quality. the following conclusions can be reached from literature review: 1. sla is a 3d printing for rapid prototyping flexible process and it is a form of additive manufacturing. 2. this process is a layer by layer method of producing objects from photosensitive polymers exposed to uv light. 3. the volume of the photosensitive materials is shrink and then distorted causing a change in dimensions leading to printed objects with less accuracy. 4. conventional epoxy, acrylate resins, or thermoplastic elastomers make up the majority of the materials utilized in sla. 5. the effect of uv light on surface changes the surface roughness. although previous researches on stereo lithography provides information that explains how process parameter affect part quality (dimensional accuracy and surface integrity). 6. dimensional accuracy in 3d sla printing is complex and is influenced by a number of variables, including the printing technology, the post processing techniques, the use of support material, and part orientation. 7. none suggested any specific results regarding optimization efforts for the parameters that combine exposure time, bottom exposure time, and bottom layers. additionally, the sla user’s systematic information on how to choose the process parameters to increase accuracy have not given in the prior studies. 8. based on the researches that was presented in current study, the number of studies that dealt with the issue of exposure duration of uv radiation is generally rather limited. 9. improvements to physical part attributes, such as the dimensional accuracy and the surface quality, have received the majority of attention in the literatures done to date but mechanical property improvements have received less attention. 8. references [1] huang, j., qin, q., & wang, j. 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(2023) 82-94، صفحة 2العدد، 19مجلة الخوارزمي الهندسية المجلد طيبة رائد محمود 94 المتغيرات على النوعية وتأثيرمراجعة لعملية الطباعة ثالثية األبعاد باألشعة فوق البنفسجية نزار قيس محمد نايف الكرخي** طيبة رائد محمود* جامعة بغداد /الهندسة الخوارزمي كلية / ، ** قسم هندسة التصنيع المؤتمت* tiba.abd2204m@kecbu.uobaghdad.edu.iq :البريد االلكتروني* nazarkais@kecbu.uobaghdad.edu.iq :البريد االلكتروني** الخالصة إلنتاجوالتي تستخدم نماذج رقمية من تصميم معان بالحاسوب باإلضافةهي نوع من تقنيات التصنيع فوق البنفسجية باألشعةثالثية االبعاد عملية الطباعة والقطاعات الصناعية وتطبيقاتها في الهندسة، التصميمعلى نطاق واسع في التصنيع، عاما، تم توظيفها 30منذ حوالي اشياء مخصصة ثالثية االبعاد تلقائيا. مختصر وتاريخ فوق البنفسجية باألشعةثالثية االبعاد تقدم مقالة المراجعة هذه ملخًصا مفيدًا وعلميًا لتقنية الطباعة .طب األسنان لتصنيع التعويضات مهمة جدًا اتنج بالضوء ونظرة عامة على المادة المستخدمة ايضا تم التطرق لها. عالوة على النوع المحدد من انواع الطابعات ثالثية االبعاد والمستند على معالجة ر .عنها تحديد ملخص لدقة تم المراجعة،من خالل هذه .ثالثية األبعاد هذا النوع من الطباعةتساب معرفه كبيره حول مزايا وعيوب الكتم إجراء االستطالع ذلك، االسفل او ووقت التعرض ووقت التعرض وعوامل مختلفة أثرت على دقتها وقياس األبعاد مثل سماكة الطبقة فوق البنفسجية باألشعة ثالثية االبعاد الطباعة .والمعالجة الالحقة ودرجة حرارة الغرفة االعلى mailto:tiba.abd2204m@kecbu.uobaghdad.edu.iq*البريد mailto:nazarkais@kecbu.uobaghdad.edu.iq <4d6963726f736f667420576f7264202d20c7e3cccf20e6cf20d5e1c7cd20e6cf20ddc7c6d2312d3135> this is an open access article under the cc by license : al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 18, no. 1, marh, (2022) p. p. 115 effect of mig welding parameters on the mechanical properties of aisi 304 austenitic stainless steels amjed m. jebbur* salah s. abed alkareem** faiz f. mustafa*** *,**,*** department of automated manufacturing engineering/ al-khwarizmi college of engineering/ university of baghdad/ baghdad/ iraq amjed.j29@gmail.com *email: **email: salah.s@kecbu.uobaghdad.edu.iq ***email: dr.faiz@kecbu.uobaghdad.edu.iq )y 2022araccepted 26 janureceived 7 november 2021; ( https://doi.org/10.22153/kej.2022.01.001 abstract the present research investigates joints welding of 304l austenitic stainless steel using metal inert gas (mig) welding method. the research explores the effect of process parameters (arc voltage, wire feed rate, and electrode wire diameter) on the mechanical properties of stainless steel. the above variables are varied respectively with 18.5, 19, 19.5 v, 116, 127, 137 mm/s, and 0.8, 1, 1.2 mm, with e308l as a filler electrode. the design matrix of the experiments was determined using the design of experiment (doe) program minitab 17 based on the levels of input elements used. the taguchi orthogonal matrix methodology (taguchi) technique was used to develop some empirical analysis for the maximum tensile strength and proper surface hardness as a function of the welding parameters mentioned above. the (����) analysis was used to statistically verify the model's adequacy. the results show that the wire feed rate had the greatest effect on the tensile strength of the welded joints when choosing the medium level of arc voltage (19 v), while the arc voltage had a substantial influence on the micro-hardness of all welded joints. the weld-joint zone is given a higher micro-hardness value compared to the base metal zone. keywords: american standard test method, gas metal arc welding, metal inert gasultimate tensile strength, vickers hardness. 1. introduction many engineering materials used in different applications exhibit different mechanical stress in a chemical corrosion environment. such applications require different metals depending on the required tasks and functions of the device’s components. sometimes, the process of saving raw materials is required, and the economic factor, is the key for the specific choice. however, austenitic-stainless steels (���� is used in the food-industry, construction, chemical, petrochemical, and power-engineering applications usually use (���� steels, because of its passive-protective layer that is created from its chromium content which leads to its enhancement in temperature-creep and corrosive-chemical environments [1]. primarily, arc-welding has long been seen to be a feasible method of combining ferrous materials. however, metal-inert gas welding (�� � is a type of gas-metal arc-welding ( �� � that uses inert gases as shielding gases. it has been considered as a solution to the consumable time in the industrial fields and certain issues such as a wide range of materials with various thicknesses, and provides a high-quality weld with the lowest welding-slag, making it preferred in the manufacturing sectors [2]. amjed m. jebbur al-khwarizmi engineering journal, vol. 18, no. 1, p.p. 115 (2022) 2 the study of this paper was on the effects of the mig welding process on the nine of 304l austenitic-stainless steel’s mechanical and microstructure properties, when changing the shielding-gas and welding-current. changing the quantity of hydrogen, by three levels, causes deferent shielding-gas condition-effects. three different levels of welding-current were used in this study. the results of this paper show that the greatest tensilestrength is realized when the current fixed at 240 �) welding and argon (��� percentage is 1.% and �� percentage is 5% . the base-metal (bm) was found to have a higher hardness value than the heat-affected zone (haz). salah s. abed-alkareem [4] discusses in his study the effects of the mag welding process parameters on the aisi 1010 low carbon steel’s mechanical strength. the chosen control parameters were welding voltage, wire feed speed, and welding speed with two levels. anova techniques were used to predict the optimal process parameters; the results showed that the weld joint’s efficiency was about 73% of the base metal’s. abid al-sahib n.k. adnan n. abood and amer a. tuama [5] report in their study the effects of mig/mag welding process parameters on the aisi din15mo3 steel hardness, microstructure, and mechanical properties using the electrode er80s-g as a filler metal with a spot joint configuration with three levels of plate thickness, welding current, and welding speed. the co2 and argon shielding gases were being used in this process. the results showed that the weld joints that were conducted with the co2 shielding gas recorded a higher value of microhardness in the weld zone compared to the heat-affected zone. furusawa and k. yasuda [6] clarified the setting, procedures for weld bead, and penetration, implemented into gas-metal arcwelding (gmaw). by changing the thickness of the 304 stainless steel from 2 to 9mm, a reference voltage ("#) was chosen (due to the absence of short circuit at or above this voltage within this process) " 308 of 1.2 mm is used as electrode filler metal. an �� + 3 percent ��mixture was chosen as a shielding-gas for the mig welding. the results of this paper showed considerable increase in penetration using welding-voltage of ("# + 2 v). a continuous acceptable bead was created when the welding was carried out at a welding-voltage of ("# − 2 v). l. s. kumar, s. m. verma, and b. suryanrayana [7] investigated the impacts of tig and mig on austenitic ss. in two procedures, several properties such as the material-strength, hardness, ductility, grain-structure, modulus of elasticity, breaking point of the tensile strength, and high-temperature zone (haz) are observed and evaluated, and a conclusion is reached at the end of the analysis process. a sample of stainless steel 304 with dimensions of 150 × 50 × 3(mm was obtained, and both welding processes were carried out. it was discovered that tig is superior to mig based on the findings of the study. the ultimate tensile strength, ultimate load, and percent of elongation are the quality-characteristics parameters to consider. a metallurgical investigation revealed the presence of porosity and intergranular corrosion, as well as other characteristics. v. chauhan and r. s. jadaun [8] studied the effects of the mig welding control process parameters on �� 304 and low-carbon steel dissimilar work-piece materials. three factors, welding-current, welding-voltage, and welding-speed, were taken into consideration in the study, with the values of each parameter changing from low to high. to determine the effect of various factors, the taguchi technique was employed. when it comes to ultimate tensile strength, the reaserchers discovered that the voltage and welding speed were both important factors to consider. i. m. omiogbemi and d. s. yawas [9] used the metal inert gas method to study the effect of input process parameters on tensilestrength, hardness, and impact-toughness of 3mm thick 304 stainless-steel that was exposed to 0.5m of hydrochloric acid at ambient temperature. the experiments were conducted using different tools such as a scanning electron microscopy (sem) and the rockwell hardness test. the obtained results show that the process at 40 (cm/min) speed and a 110 amp current, lead to an increase in the tensilestrength, and the hardness of a weldment is a function of the grain size of the weldment as well as the structural integrity of the welded-joints. s. a. rizvi and w. ali [10] studied the optimization of diferent gmaw welding process parameters on the mechanical-properties and weldability. it was decided that different welding factors, such as the welding-current, wire-feed speed, and gas-flow rate, would influence the weldability of ss304h by using the statistical approach, which was implemented. the tensile-strength, toughness, microhardness, and mode of fracture of ss304h were all measured to establish its weldability. the welding-voltage had the greatest impact, whereas the gas-flow rate had the smallest impact on the ultimate-tensile strength of the welded-joints. it is observed that the third-level of welding-voltage, the second-level of gas-flow rate, and the thirdlevel of wire-feed speed give normal values of hardness er. saurabh and v. s. aher [11]. the process parameters and their selection were amjed m. jebbur al-khwarizmi engineering journal, vol. 18, no. 1, p.p. 115 (2022) 3 important to achieve the required outcomes. however, the present work considered different optimization techniques. the outcomes of the welding process are measured in terms of strength, penetration, reinforcement, height, and hardness. in this work the results showed that the increase in welding-voltage from 18 to 22 v causes the strength value to increase from 358 (mpa) to 395.75 (mpa), and then at 24 v, the strength is maximum as 455.25 (mpa). the higher the voltage, the higher the strength a. furqan and m. amarnadha [12] experiments based on the taguchi-approach have been utilized to investigate the impact of mig-welding parameters such as welding-current, welding-voltage, and weldingspeed on the ultimate-tensile strength ()*�) of ���� 1050 mild-steel material during the welding procedure. analyzing the welding properties of a material and optimizing the welding settings involves the use of an orthogonal-array, signal to noise (�/�) ratio, and (�����) analysis techniques. the result is obtained in the form of a contribution from each parameter, and it is via this process that the best parameters for maximum tensile strength are discovered. according to the findings of this study, welding current and welding speed are the two most important characteristics that determine the tensile-strength of welded-joint steel. the mechanical properties of weld joint had been studied by researchers however tensile strength from an austenitic stainless steel joint which used mig welding was not enough. this study aimed to explore the effects of welding voltage, electrode wire diameter, and electrode feed rate of mig welding on the tensile strength, and hardness of (304l) austenitic-stainless steel.the purpose of the research was to find only the optimal factors that are of benefit to welders for the purpose of working with them to find the best mechanical properties and a high quality weld joint. 2. experimental procedure 2.1. selection of workpiece-material the most common form of stainless-steel is austenitic stainless steel due to its high nickel content effect. austenitic stainless steel is the most corrosion-resistant stainless steel with very good mechanical properties. because stainless steel is classified into several types, including austenitic, ferritic, and martensitic, the choice comes on austenitic stainless steel 304l because this is the most expensive one, it has a wide variety of applications, and its ease of availability on the market. table 1 shows the chemical composition of 304l stainless steel that was (company for inspection and engineering rehabilitation) (sier) compared with standard value and compared with the standard according to the astm a240 standard [ 13]. table 1, chemical contents of (304l) workpiece used in this work.” composition c% “”mn%” p% s% si% cr% ni% n% nominal 0.08 max 2.00 max 0.045 max 0.030 max 0.75 max 18.0020.00 max 8.0010.05 max 0.10 max experimental 0.04 0.932 0.0175 0.0005 18.85 8.66 in this work, a sheet of 304l stainless steel alloy with thickness of (4 mm) as welding specimens was employed. a cold press machine was used to cut the sheets to the desired dimensions of (200×100) mm as welding specimens, and the two sheet’s edges were prepared with a squire butt joint with a single welding pass as shown in figure 1. using a consumable electrode, er308l austenitic stainless steel was used, and it conforms to certification aws a5.9/asme sfa a5.9. table 2 show the chemical composition of the electrode filler metal. table 2, chemical contents of e308l filler metal used for this work. composition c% cr n mo mn si p s n cu fe e308l 0.03 19.522 9-11 0.75 1-2.5 0.30.65 0.03 0.03 0.75 0.75 base . amjed m. jebbur al-khwarizmi engineering journal, vol. 18, no. 1, p.p. 115 (2022) 4 fig. 1. butt joint design for two sheetsall dimensions in mm. 2.2 experimental work during the welding process, to ensure that the two sheets are carefully welded, the process was achieved by tightening and clamping the two sheets square butt design on the welding board configurations. the welding process was done manually by a skilled technician welder in the general company for engineering inspection and qualification. the welding machine used in this work was the type lincoln electric inverter as present in (sier) state company, as shown in the figure 2. the wire systems are included with an automatic feeder in this welding machine. the welding machine provides a dc voltage ranging from 10 to 40volts and a welding current of 40 to 600 amperes. the transistor in this circuit is used as an electronic switch to pass the current on and off at a very high speed, in order to adjust the strength and voltage of the welding current without fixed levels of adjustment. thus, it provides the possibility of adjusting the welding parameters by a remote control and reduces the risk of a sudden rise or fall in the network voltage [14]. fig. 2. lincoln electric machine used in this work. 2.2.1 ultimate tensilestrengthtests (uts) the tensile tests were performed in the sier state company. a universal testing machine called “united” was obtained in the state company for inspection and engineering rehabilitation (sier) and was used in this work. the tensile test was performed at 0.1 kn preload, 20 mm/min crosshead speed, and the specimen were loaded at a rate of 1.5 kn/min.the specimens were taken from the cross-sectional direction of base-metal, in a perpendicular orientation to the welded line. the transverse tensile tests were performed on subsiding sheet specimens at room temperature with dimensions that were presented according to the astm: e8/8m standards [15], as shown in figure 3.the location of fracture for all nine specimen is almost at the midsection of the specimens. amjed m. jebbur al-khwarizmi engineering journal, vol. 18, no. 1, p.p. 115 (2022) 5 fig. 3. astm: e8/8m standard dimensions for tensile test specimens: (a) real& (b) schematic of the tensile test specimens. 2.2.2the vickers hardness tests (vh) two directions were taken to achieve the measurement microhardness. the first direction was in the transverse direction with (2 mm) perpendicular to the base-plate surface, and the longitudinal direction that is parallel to the basemetal surface was the second direction taken to achieve the measurements for both zones, the weld-zone (w.z), and the base-metal zone( bm.z), by using the vickers’s micro hardness testing device. the reading of measurements were initially started at the weld-zone (wz), heat affected zone (haz), and finally at the base-metal zone (bm) on both sides of the weld line with a distance interval of about 2 mm between one reading and the other as explained in figure 4. table 4 shows the recorded reading and its average of two readings for both zones for the nine specimens of this work. fig. 4. directions of measuring microhardness for the welded joint. 2.3 the design of experimental (doe) before achieving the welding process, several stages (choosing the proper parameters that are involve in the experiment, obtaining the features of the community under study,making the decision for the required amount of data which belongs to features of the experiment, and choosing the number of levels for each parameter) are necessary to reduce the errors while archiving the experiments and satisfying the optimum process parameters at the same time. the aim was to predict the simple difference between the parameters and their levels. taguchi’s design of experiment (doe) tool with a set of descriptive statistics can be an effective method for this purpose. the method involves the selection the ,(oa) orthogonal array which employs to conduct the experiments. in the present work, the process parameters (welding-voltage (v), the electrode-wire diameter (wd), and the electrode-feed rate(f)) have been chosen with three levels for each parameter. taguchi's descriptive statistics mean, signal-tonoise (s/n) ratios, and the formula (smaller the better, nominal is the best,and larger the better) for the (s/n) can be organized according to the problem aspects and response criterias, and can be employed to satisfy the optimal value and their levels of the given process parameters. table 3 explains the impact of the setting factors (welding voltage, electrode wire diameters, and electrode feed rate) on the tensile-strength and coss-sectional amjed m. jebbur al-khwarizmi engineering journal, vol. 18, no. 1, p.p. 115 (2022) 6 hardness behavior by using the taguchi orthogonal-array that was designed and implement by using the minitab17 program [16], [17]. table 3, input parameters and their levels by using doe for this work. “exp. no.” v (v) wd (mm) f (mm/s) “ 1” 18.5 0.8 116 “2” 18.5 1 127 “3” 18.5 1.2 137 “4” 19 0.8 127 “5” 19 1 137 “ 6” 19 1.2 116 “7” 19.5 0.8 137 “8” 19.5 1 116 “9” 19.5 1.2 127 3. results and discussions analysis of variance is an analysis tool used in statistics that splits an observed aggregated variability found inside a data set into two parts: systematic factors and random factors. the systematic factors have a statistical influence on the given data set, while the random factors do not. analysts use the anova test to determine the influence that thr independent variables have on the dependent variables in a regression study. finding the parameters that affect the ultimatetensile-strength .)*��, vickershardness .���, and the quality of all specimens are the goal of these experiments. the orthogonal array is the base of these experiments with the goal of relating the best levels of the welding voltage, wire diameter, and wire feed rate. the work includes conducting the experiments as per the orthogonal array to obtain the various combination results. 3.1 ultimate-tensile test.012� a visual inspection was performed after each experiment, and the suitable area of the weld surfaces was selected for preparation of the tensile test specimens after each experiment. to evaluate the results of tensile test for each welding joint, an average of two specimens were taken in a perpendicular orientation to the welded line. table 4 shows the average and weld-joint efficiency for nine experiments with its joints efficiency achieved in this work. joint efficiency is the ratio of the strength of the joint compared to the strength of the base metal. this ratio is called joint efficiency or joint quality factor. an efficient joint is one that is just as strong as the base metal. the weld joint efficiency computed by using the equation below [18]. weld joint efficiency (wje) (%) = 345 67 89: ;6<=8 345 67 >?@: a:8?b × 100 table 4, results of average for nine experimental 012 tests of this work exp. no. experimental-reputation averg.uts (mpa). weld-jointefficiency ( %) 1 2 1 395.39 534.63 466.1 74 2 610 671.81 640.905 102 3 659.19 642.18 650.685 103.9 4 651.11 636.51 643.81 102.8 5 645.2 680.41 662.805 105.8 6 619.79 682.67 651.23 104 7 654.07 663.42 658.745 105.1 8 527.07 426 476.535 78.5 9 559.7 569.11 564.405 90 as can be seen in table 5, the ultimate-tensile strength reaches its maximum and minimum values of (652.71mpa) and (466.1mpa) respectively. at first, the low welding voltage causes the minimum value of tensile strength, then increasing the welding-voltage to the medium level leads to the amjed m. jebbur al-khwarizmi engineering journal, vol. 18, no. 1, p.p. 115 (2022) 7 increase of the tensile strength, until a threshold value is reached. thereafter, the high level of the welding voltage starts decreasing the tensile sample after testing, as shown in figure 5. tables 5, 6, and 7, show the statistical analysis results for the tensile responses which were obtained by the taguchi method. a) specimens (1 – 3) low voltage level b) specimens (4 – 6) med. voltage level c) specimens (7 – 9) high voltage level fig. 5. tensile test specimens with three levels of arc voltage. from the visual inspection, the low results of the tensile test are due to the lack of penetration for samples 1 to3 and fast cooling at the voltage level for samples 7 to 9, this is in agreement with the reference [19]. tables 5, 6, and 7, show the statistical analysis results for tensiles, the responses were obtained by the taguchi method. table 5, results of statistical analysis of experiments by taguchi technique for uts run. no. v (v) wd (mm) f (mm/s) uts (mpa) snra1 mean1 1 18.5 0.8 116 466.1 53.6530 481.560 2 18.5 1 127 640.905 56.1359 640.905 3 18.5 1.2 137 650.685 56.2674 650.685 4 19 0.8 127 643.81 56.1752 643.810 5 19 1 137 662.805 56.4277 662.805 6 19 1.2 116 651.23 56.2747 651.230 7 19.5 0.8 137 658.745 56.3743 658.745 8 19.5 1 116 476.535 53.5619 476.535 9 19.5 1.2 127 564.405 55.0318 564.405 table 6, response table for s/n of uts. level v (v) wd (mm) f (mm/s) 1 55.35 55.40 54.50 2 56.29 55.38 55.78 3 54.99 55.86 56.36 delta 1.30 0.48 1.86 rank 2 3 1 amjed m. jebbur al-khwarizmi engineering journal, vol. 18, no. 1, p.p. 115 (2022) 8 table 7, response table for a meanof uts “level “ v (v) wd (mm) f (mm/s) “1” 591.0 594.4 536.4 “2” 652.6 593.4 616.4 “3” 566.6 622.1 657.4 “delta” 86.1 28.7 121.0 “rank” 2 3 1 the ranks indicate that wire feed rate has the biggest influence on both the s/n ratio and the mean in our experimental analysis. for s/n, the arc voltage has the next greatest influence, followed by electrode wire diameter. from table 6 and table 7, the value of the s/n ratio and mean for all parameters is compatible by taking the large number so that we do not need to make a prediction. the main effect plot for the s/n ratio and the mean s/n ratio is shown the relationship between them in figures 5 and 6. fig. 6. main effect plot of s/n ratio for uts. fig. 7. main effect plot of the mean for uts. the optimum value of parameters that based on the highest number of s/n ratio and welding voltage �.��.19 c�, electrode wire diameter of d.e�.1.2ff�, and electrode feed rate g.e�.137 ii j �. the optimum level amjed m. jebbur al-khwarizmi engineering journal, vol. 18, no. 1, p.p. 115 (2022) 9 (�.��, d.e�, g.e�) for the optimum reach of tensile-strength. , however, this experimental result, and there parameter’s levels do not found in the nine experiments obtained in table 3. taguchi orthogonal array only represent nine experiments from all the possibilities of experiment [3e = 9 experiments]. 3.2 vickers-hardness.kl�test figure 8 depicts the results that the microhardness profile tests achieved by using the vickers hardness test method for aisi 304l stainless steels. the measurements were at the center of the cross-section area for both the welded zones (wz), and base-metal zone (bm). both no. 1 and 2 were shown were shown to have higher hardness values than other specimens, this is due to use a lower welding voltage level which causes the lower heat input to reduce the cooling rate and this turns to decrease in the microhardness in the weld joints [18]. in general, the hardness values of the weld-zones are higher in the center of the fusion zone than the base-metal zone, and tend to decrease with a little shift along the specimens' length. this might be due to the existence of electrode components and a difference in voltage [20]. fig. 8. the results of the vickers’s micro-hardness profile for nine specimens. tables 8, 9, and 10, show the statistical analysis results for cross-sectional hardness, the responses were obtained by the taguchi method. table 8, the statistical analysis results for hardness, responses obtained by the taguchi method. run. no. v (v) w.d (mm) f (mm/s) vh snra1 mean1 1 18.5 0.8 116 268.860 48.5905 268.860 “2 18.5 1 127 246.700 47.8434 246.700 3 18.5 1.2 137 249.100 47.9275 249.100 4 19 0.8 127 244.868 47.7786 244.868 5 19 1 137 242.366 47.6894 242.366 6 19 1.2 116 240.233 47.6127 240.233 7 19.5 0.8 137 237.360 47.5082 237.360 8 19.5 1 116 238.800 47.5607 238.800 9 19.5 1.2 127 240.100 47.6078 240.100 table 9, response for signal to noise ratios for vh larger is the best level v (v) wd (mm) f (mm/s) amjed m. jebbur al-khwarizmi engineering journal, vol. 18, no. 1, p.p. 115 (2022) 10 1 48.12 47.96 47.92 2 47.69 47.70 47.74 3 47.56 47.72 47.71 delta 0.56 0.26 0.21 rank 1 2 3 table 10, response ofmeans for vh tests level iv (v) iwd (mm) if (mm/s) 1 254.9 250.4 249.3 2 242.5 242.6 243.9 3 238.8 243.1 242.9 delta 16.1 7.7 6.4 rank 1 2 3 the test was performed for microhardness of the specimens weld zone. the ranks indicate that arc-voltage has the biggest influence on both the s/n ratio and the mean in our experimental analysis. for s/n, the electrode wire-diameter has the next greatest influence, followed by electrodefeed-rate. from tables 9 and 10 the value of the s/n ratio and mean for all parameters is compatible by taking the large number so that we do not need to make a prediction. the main effect plot for mean and s/n ratio is illustrated in figure 8 and figure 9, respectively. fig. 9. effect of a plot for s/n ratios for microhardness test. amjed m. jebbur al-khwarizmi engineering journal, vol. 18, no. 1, p.p. 115 (2022) 11 fig. 10. the mean for the microhardness test. the optimum value of parameters that based on the highest number of s/n ratio with a welding voltage .�.m�� of 18.5 v, an electrode wire diameter . d.m�� of 0.8mm, and an electrode feed rate .g.m�� of 116 ii j . the optimum level for the ( �.m�, d.m�, g.m�� process parameters was selected according to the standard (large is better) value of s/n ratio to have a maximum reaction that affected the optimum reach of hardness. however, this experiment’s results and their parameter’s levels are not found in the nine experiments obtained in table 3. taguchi orthogonal array only represents nine experiments from all the possibilities of the experiment. 3.3. analysis of variance (pqrkp) the analysis of variance (�����) is statistical process used for determining the p% (percentage of contribution) for each parameterand their significance level. the minitab-17 program was used to anticipate the ideal value for this situation [21]. 3.3.1 analysis of variance (pqrkp�for the tensile-strength(uts) test the anova test was conducted using welding-voltage, wire diameter, and wire feed rate to show the effects of these parameters on the ultimate tensile-strength .)*��. table 11 shows the results of the �����) analysis for the )*� tests. table 11, anova analyses for uts source “df” “ seq-ss adj-ss adj-ms f-value p-value contribution% v 2 11795 11795 5897.6 1.12 0.472 25.30% w.d 2 1576 1576 787.9 0.15 0.870 3.38% w.f.r 2 22707 22707 11353.5 2.15 0.317 48.71% error 2 10538 10538 5268.9 22.61% total/ 8 46616 100.00% where: p = the confidences interval f = fisher test �� = = ∑ .tu − t��v u ...(1) where, tu is the observed �/� ratio value of the response, w is the number of observations or experiment numbers and t is the mean of �/� ratio. ��= xx yz ..(2) ms means the mean sum of squares due to the source. ss sum of squared deviation due to the source . amjed m. jebbur al-khwarizmi engineering journal, vol. 18, no. 1, p.p. 115 (2022) 12 dg = means "the degrees of freedom in the source." it can be noticed that the large parameter effect on uts is the wire. feed. rate with 48.71% percentage, followed by arc voltage with 25.30% percentage, and followed by the wire diameter with 3.38% percentage. which means that these parameters have a large effect on tensile strength compared to the other parameters. 3.3.2 analysis of variance.pqrkp� for the microhardness(vh) test the results of statistical processing for the analysis of variance (anova) for hardness test (shown in table 12) are used for determining the p% for each control parameter. it can be noticed that the largest parameter effect on hardness test is the arc voltage circuit with (57.94%) percentage followed by wire diameter with (15.21%) percentage followed by wire feed rate with (9.56%). table 12, the average of each response source df “seq-ss adj-ss adj ms f-value “pvalue icontribution% v 2 427.94 427.94 213.97 3.36 0.229 57.94% w. d 2 112.30 112.30 56.15 0.88 0.532 15.21% w.f.r 2 70.54 70.54 35.27 0.55 0.644 9.56% error 2 127.45 127.45 63.72 63.72 17.26% “total” 8 738.22 100.00% it can be noticed that the large parameter effect on cross-sectional-hardness is the welding voltage with followed by the wire diameter and followed the wire feed rate. in the table above is the analysis of the anova for the tensile test, the last column in the table shows the contribution (the effect of each factor on the final tensile test and according to the percentages mentioned in the same column (contribution)). it is clear that the effect of voltage is large (57.9%), followed by the effect of wd by (15.21%), and finally wfd by 9.56% . 4. conclusions 1. the tensile-strength, and microhardness of different welded joints are significantly affected by input process parameters. however, a good resultof these mechanical properties can be satisfied by choosing the required process parameter of the given welding process. 2. wire feed rate has the majority influence on “tensile strength”, accounting for (48.71%) of the total, followed by arc voltage (25.3%) and wire diameter (3.38%). 3. welding-voltage has the greatest influence on the “microhardness”, accounting for (57.94%) of welding voltage, followed by wire diameter (15.21%), and wire feed-rate of 9.56% respectively. 4. the confirmation test for the improved welding parameters ensures that the higher final tensile stress factor value is taken better so that the weld joint is strong enough to resist joint fracture, and a lower value is taken for the finer hardness factor, which is better to prevent brittleness as to not break the weld joint. scope for future work and recommendations 1. study the effects of process parameters on mig butt joint for the metals with high melting temperature such as iron, steel, and titanium. 2. optimization of process parameters for the mig butt joint to improve the mechanical behavior of 304l stainless steel alloy by using new methods to analyze the results and choosing other process parameters such as (welding speed, current, gas flow rate, plate thickness, etc.). 3. investigate optimization of process parameters for mig joint of dissimilar alloys. 4. 4study the effect of weld joint geometry dimensions on thermal for mig process for different stainless steel alloys using the technical advancing devices for measuring and analyzing the temperatures during the welding process. 5. investigate the influence of the strength fusion region heating mechanism and inspection the internal defects formation for mig process by ultrasonic testing of welded parts. 6. in this present work-study, we used single-pass welding, so we recommend using multi-pass to enhance the mechanical properties in the welding zone. 7. in this work recommends using more advanced inspections for the mechanical properties in the welding zone. amjed m. jebbur al-khwarizmi engineering journal, vol. 18, no. 1, p.p. 115 (2022) 13 list of abbreviations gmaw gas metal arc welding mig metal inert gas ass austenitic stainless steel aws american welding society e308l american welding standard code for filler metal wz weld zone haz heat effected zone bm base metal astm american society for testing of materials doe design of experimental oa orthogonal array anova analysis of variance s/n signal to noise ratio uts ultimate tensile strength hv vickers microhardness test msn mean squared deviation df degrees of freedom n number of trials av. average wje weld joint efficiency f fisher test p the confidences interval l9 the nine experiments that design by oa taguchi 5. references [1] r.molak and k. paradowski, “measurement of mechanical properties in a 316l stainless steel welded joint”, international journal of pressure vessels and piping, vol. 86,pp. 43–47, 2009. [2] a.s. hameed,“experimental investigation for multi characteristics optimization of mig welding on 304 stainless steel using desirability function analysis”, journal of mines, metals & fuels. vol. 68, no.4, pp. 144 – 149, 2020. [3] gulencand b.develib,” experimental study of the effect of hydrogen in argon as a shielding gas in mig welding of austenitic stainless steel”. international journal of hydrogen energy, vol. 30: pp. 1475 – 1481, 2005. [4] salah s. abed-alkareem “determination of welding velocity and arc energy for fusion mag welding joint” al-khwarizmi eng. journal, vol. 10, no. 4, pp. 64 – 80 2014. [5] abid al-sahib n.k., adnan n. abood and amer a. tuama “welding of low alloy steel din ismo3 by mig/mag spot “alkhwarizmi eng. journal, vol.2, no. 2, pp. 1 – 19 2006. [6] furusawa and k. yasuda, “the effect of gas metal arc welding (gmaw) processes on different welding parameters”. procedia engineering, vol. 41, pp 1502 – 1506, 2012. [7] l. s. kumar s. m. verma, and b. suryanrayana, “analysis of welding characteristics on stainless steel for the process of tig and mig with dye penetrate testinhg”. international journal of engineering and innovative technology, vol. 2, pp. 283 – 290, 2012. [8] v. chauhan and r. s. jadaun, “parametric optimization of mig welding for stainless steel (ss-304) and low carbon steel using taguchi design method”, international journal of recent scientific research. vol. 6, pp. 2662 – 2666, 2015. [9] i. m. omiogbemi and d. s. yawas,” effects of metal inert gas welding parameters on some mechanical properties of austenitic stainless steel in acidic environment”, nigerian journal of technology (nijotech), vol. 36, no. 3, pp. 835 – 843, 2017. [10] s. a. rizvi and w. ali, “optimization of welding parameters and microstructure and fracture mode characterization of gma welding by using taguchi method on ss304h austenitic steel”, mechanics and mechanical engineering, technical university of lodz, vol. 22, no.4, pp.11211131, 2018. [11] er. saurabh and v. s. aher,” parametric optimization of mig welding process to improve its tensile strength”, international journal of research and development, vol. 4, pp. 75 – 82, 2019. [12] a. furqan and m. amarnadha, “optimization of mig welding parameters for improving strength of welded joint”, journal of interdisciplinary cycle research, vol. 6, pp 128 – 135, 2020. [13] astm, "standard specification for heatresisting chromium and chromium-nickel stainless steel plate, sheet, and strip for pressure vessels", a240, 2006. [14] ieee criteria for class ie electric systems, ieee standard 308, 1969. [15] american society for metal, “asm metal handbook”, vol.21 copyright 2012. [16] e. dean, r. unal, “taguchi approach to design optimization for quality and cost: an overview,” int. soc. parametr. anal., pp. 1– 10, 1991. [17] o. hinkelmann, “design and analysis of experiments, introduction to experimental amjed m. jebbur al-khwarizmi engineering journal, vol. 18, no. 1, p.p. 115 (2022) 14 design”. canada: john wiley & sons, inc., 2008. [18] kumar a, gautam ss, kumar a. heat input and joint efficiency of three welding processes tig, mig and fsw using aa6061. int j mech eng rob res, vol. 1, p.p. 89–94 2014. [19] t. e. abioye and o.o. gbadeyan, "analysis of the mechanical properties and penetration depth of gas metal arc welding on aisi 304 stainless steel," int. j. microstructure and materials properties, vol. 14, no. 1, 2019. [20] david, s.s. babu, & j.m. vitek, "welding solidification and microstructure", oak ridge national laboratory, vol. 32, no. 3, 2003. [21] herry and oktadinata, "microstructure and hardness profile of dissimilar lap joint of type 304 stainless steel to ss400 carbon steel”, kementerian perindustrian metal indonesia, vol. 41 no. 2, pp. 47-54, 2019 ) 2022( 115، صفحة 1العدد، 18مجلة الخوارزمي الهندسية المجلد امجد محمد جبر 15 aisi 304على الخواص الميكانيكية للفوالذ المقاوم للصدأ نوعmigتأثير متغيراتلحام فائز فوزي مصطفى*** صالح صبيح عبد الكريم** محمد جبر* امجد *،**،***قسم هندسة التصنيع المؤتمت/ كلية الهندسة الخوارزمي/ جامعة بغداد amjed.j29@gmail.com*البريد االلكتروني: salah.s@kecbu.uobaghdad.edu.iq**البريد االلكتروني: dr.faiz@kecbu.uobaghdad.edu.iqروني: ت***البريد االلك خالصة ال تأثير لتوضيح) migباستخدام طريقة اللحام بالغازالخامل للمعادن ( )٣٠٤(lنوع قاوم للصدا من الفوالد الم لحام انتاج وصالت دراسة هدا البحث يتضمن ملم/ ) ١٣٧, ١٢٧, ١١٦( ،فولت )١٩.٥, ١٩, ١٨.٥ (ثالثة مستوياتوبسلكالقطر كذلك جهد القوس ومعدل تغذية السلك وتتضمن التي العملية المتعيرات ا تصميم مصفوفة . تم تحديدللصدأ للفوالذ المقاوم حشو,على الخواص الميكانيكية معدنك) ٣٠٨er(وسلك اللحام المستخدم نوع ، ملم )١٫٢, ١, ٠٫٨(ثانيهو للحصول (anova) استخدم تحليل التباين ومج البرنا في المصفوفةالمتعامدة منهجية متستخدأ ،االدخال عواملمستويات وفق تاكوشي الحاسوبي البرنامج الدور االكبر كان له السلك اظهرت النتاىج ان معدل تغذية .المذكورة اعاله اللحام تغيراتكدالة لمالدقيقة للملحومات ة دصالال ونتائج ألجهاد الشد النهائي العلى دة الدقيقة لجميع عمليات اللحامعلى الصال ا"كبير ا"كان لجهد القوس ثأثير . بينما )فولت ١٩(جهد القوس المتمثل ب مستوى الشد عند اختيار على اجهاد الا"تأثير اعلى مقارنة بمنطقة المعدن االساس. تهامنطقة اللحام قيمة صالد ومن جراء الفحوصات المختبرية توضح القيم ان microsoft word ???? ?? ??? ?? ????. 2228 this is an open access article under the cc by license : al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 17, no. 3, sptember, (2021) p. p. 22 28 robust computed torque control for uncertain robotic manipulators maryam s. ahmed* ali hussien mary** hisham h. jasim*** *,**,***department of mechatronics/ al-khwarizmi college of engineering/ university of baghdad *email: maryamsadeq97@gmail.com **email: alimary76@kecbu.uobaghdad.edu.iq ***email: mschisham@gmail.com (received 27 july 2021; revised 20 august 2021; accepted 1 september 2021) https://doi.org/10.22153/kej.2021.09.002 abstract this paper presents a robust control method for the trajectory control of the robotic manipulator. the standard computed torque control (ctc) is an important method in the robotic control systems but its not robust to system uncertainty and external disturbance. the proposed method overcome the system uncertainty and external disturbance problems. in this paper, a robustification term has been added to the standard ctc. the stability of the proposed control method is approved by the lyapunov stability theorem. the performance of the presented controller is tested by matlab-simulink environment and is compared with different control methods to illustrate its robustness and performance. keywords: computed torque control, linear matrix inequality, robotic control, robotic manipulato. 1. introduction today, the robotics systems enter into many applications such as, industrial applications, manufacturing, medical fields, and space application [1] . precise positioning is an important desired feature of the robot manipulator. the robot manipulator can be considered as a nonlinear system that suffering from high nonlinearity and external disturbance. the main problem is how to control the robot taking into account the system uncertainty and external disturbance. however, in recent years, significant and rapid progress had been made in the field of control, to solve the control problem. different control strategies have been proposed. pid control proposed by many researchers because due to its simplicity and ease of implementation. abhishek and dayal presented pid controller optimized by particle swarm optimization (pso) to stabilize the gait humanoid robot [2]. ignacio proposed design an adaptive pid controller based reinforcement learning [3]. structured and unstructured uncertainties and external interference, it is difficult to obtain an accurate dynamics model of the robotic arm. therefore, many control schemes for unknown dynamic models of robot manipulators have been proposed. a robust control strategy is an important method that can handle the system uncertainties and disturbances. sliding mode control (smc) is an effect robust control method that applied successfully in control different robotic manipulators.in [4], smc is combined with fuzzy logic technique to control robot manipulator in task space. mary and kara presented robust control maryam s. ahmed al-khwarizmi engineering journal, vol. 17, no. 3, p.p. 2228 (2021) 23 method for control 2 links robotic arm by using linear matrix inequality (lmi) to tune the control gains [5]. in (wu and huang , 2021), fraction fractional calculus utilized to design hybrid controller with the sliding mode control for trajectory tracking of mobile robot manipulator. in (chen et al. , 2019), radial basis function neural network used with smc for control n links robot arm taking into account the actuator dynamic. however, the chattering is the important drawback in smc [8,9]. ctc is an efficient control used in robotic control problem. ctc method require knowing the dynamic of robotic arm and in practice, determine the accurate dynamic of robotic arm may be difficult [10,11,12]. thus, this paper proposed a new method that can improve the robustness of the standard ctc against system uncertainty and external disturbance. 2. dynamic model of the robotic manipulator the dynamic model of the robotic arm system can be written as follows: 𝑀 𝑞 𝑞 𝐶 𝑞, 𝑞 𝑞 𝐹 𝑞 𝐺 𝑞 𝜏 𝜏…(1) where 𝑞, 𝑞, 𝑞 ∈ 𝑅 refer respectively to the angular position, velocity, and acceleration vectors of robotic manipulator joints, 𝑀 𝑞 ∈ 𝑅 refers to the inertia matrix, 𝐶 𝑞, 𝑞 ∈ 𝑅 denotes a centripetal and coriolis vector force, 𝐹 𝑞 ∈ 𝑅 is the friction torque vector, 𝐺 𝑞 ∈ 𝑅 represents loading of the gravity, 𝜏 ∈ 𝑅 is the external disturbance, and 𝜏 ∈ 𝑅 refers to the joints torque vector. in particular applications, getting the accurate dynamic of the robotic manipulator are not easy due to model uncertainties and external disturbance. therefore, the model uncertainty can be included in the dynamic model as follows: 𝑀 𝑞 𝑀 𝑞 ∆𝑀 𝑞 …(2) 𝐶 𝑞, 𝑞 𝐶 𝑞, 𝑞 ∆𝐶 𝑞, 𝑞 …(3) 𝐹 𝑞 𝐹 𝑞 ∆𝐹 𝑞 …(4) 𝐺 𝑞 𝐺 𝑞 ∆𝐺 𝑞 …(5) where 𝑀 𝑞 , 𝐶 𝑞, 𝑞 , 𝐹 𝑞 , and 𝐺 𝑞 represent the nominal model of the robotic system and it can be known, whereas ∆𝑀 𝑞 , ∆𝐶 𝑞, 𝑞 , ∆𝐹 𝑞 and ∆𝐺 𝑞 denote the uncertainty part of the robotic manipulator dynamic model and it cannot be determined exactly. in this paper, we assume the following: assumption 1. the desired trajectories 𝑞 with their first and second derivatives 𝑞 and 𝑞 are continuous and bounded as follows: |𝑞 𝑡 | 𝑀 , |𝑞 𝑡 | 𝑀 , |𝑞 𝑡 | 𝑀 , …(6) with 𝑀 , 𝑀 , and 𝑀 being positive constants[5]. 3. computed torque control computed torque control is an important control method that applied successfully in robotic system control when there is no model uncertainty then, the dynamic model in (1) becomes 𝑀 𝑞 𝑞 𝐶 𝑞, 𝑞 𝑞 𝐹 𝑞 𝐺 𝑞 𝜏 …(7) the standard ctc is 𝜏 𝑀 𝑞 𝑞 𝑘 𝑒 𝑘 𝑒 𝐶 𝑞, 𝑞 𝑞 𝐹 𝑞 𝐺 𝑞 …(8) 𝑒 𝑞 𝑞 …(9) where 𝑒 is the tracking error, 𝑘 and 𝑘 are the proportional and derivative control gain matrices. by substituting (8) in (7), 𝑞 𝑘 𝑒 𝑘 𝑒 0 …(10) it is obvious that the roots of (10) will lie on the left half plane if the control gain matrices 𝑘 and 𝑘 are positive, which implies that the actual trajectory can track desired trajectory and error signal will converge to zero. 4. proposed robust ctc design a robust ctc controller will be presented to improve the performance of the ctc. the proposed control law is 𝜏 𝑢 𝑢 …(11) 𝑢 𝑀 𝑞 𝑞 𝑘 𝑒 𝑘 𝑒 𝐶 𝑞, 𝑞 𝑞 𝐹 𝑞 𝐺 𝑞 …(12) where 𝑢 is a standard computed torque that defined in (8). 𝑢 is a robust control term that can handle the system uncertainties and external disturbance. design of robust compensator controller to solve the problem robustness of the standard ctc, the following control is proposed: 𝑢 𝑘 𝑠𝑖𝑔𝑛 𝛾e t e t …(13) where 𝑘 is the gain of the robust term, 𝛾 is a positive constant. sign is the sign function. theorem 1. consider the robotic manipulator dynamic model (1) with the proposed control law in (2), the closed loop controlled system will be maryam s. ahmed al-khwarizmi engineering journal, vol. 17, no. 3, p.p. 2228 (2021) 24 stable and the tracking error and its derivative will converge to zero. proof. the lyapunov function candidate selected as follows: 𝑆 t 𝛾e t e t …(14) 𝑞 𝑞 𝛾 𝑞 𝑞 …(15) by simple calculations it can be obtained the following 𝑆 𝑡 𝑞 𝑞 …(16) 𝑆 𝑡 𝑞 𝑞 …(17) 𝑉 𝑡 𝑆 𝑀𝑆 …(18) 𝑉 𝑡 𝑆 𝑀𝑆 𝑆 𝑀𝑆 …(19) 𝑆 𝑀𝑆 𝑆 𝐶𝑆 ...(20) 𝑆 𝑀 𝑞 𝑞 𝐶 𝑞 𝑞 …(21) 𝑆 𝑀𝑞 𝐶𝑞 𝑀𝑞 𝐶𝑞 …(22) 𝑆 𝑀𝑞 𝐶𝑞 𝐹 𝐺 𝜏 …(23) sub (11) in (23) 𝑉 𝑡 𝑆 𝑀𝑞 𝐶𝑞 𝐹 𝐺 𝑢 𝑢 …(24) sub (12) and (13) in (24) 𝑆 𝑀𝑞 𝐶𝑞 𝐹 𝐺 𝑀 𝑞 𝑞 𝑘 𝑒 𝑘 𝑒 𝐶 𝑞, 𝑞 𝑞 𝐹 𝑞 𝐺 𝑞 𝑘 𝑠𝑖𝑔𝑛 s …(25) let 𝜌 𝑡 𝑀𝑞 𝐶𝑞 𝐹 𝐺 𝑀 𝑞 𝑞 𝐶 𝑞, 𝑞 𝑞 𝐹 𝑞 𝐺 𝑞 …(26) 𝑆 𝜌 𝑡 𝑀 𝑞 𝑘 𝑒 𝑘 𝑒 𝑞 𝑘 𝑠𝑖𝑔𝑛 s ...(27) 𝑉 𝑡 𝑆 𝜌 𝑡 𝑘 𝑀 𝑞 𝑒 𝑘 𝑀 𝑞 𝑒 t 𝑘 𝑠𝑖𝑔𝑛 s …(28) 𝑉 𝑡 𝑆 𝜌 𝑡 𝑀 𝑞 𝑘 𝑘 𝑘 𝑒 𝑒 t 𝑘 𝑠𝑖𝑔𝑛 s …(29) if parameters 𝑘 and 𝑘 selected as follows 𝑘 𝑘 𝛾 …(30) sub (30) in (29), yields: 𝑉 𝑡 𝑆 𝜌 𝑡 𝑘 𝑀 𝑆 𝑘 𝑠𝑖𝑔𝑛 s …(31) 𝑆 𝑘 𝑀 𝑆 𝑆 𝜌 𝑡 𝑘 …(32) ‖𝑀 𝑞 ‖‖𝑘 ‖‖𝑆‖ ‖𝑘‖‖𝑆‖ ‖𝜌 𝑡 ‖‖𝑆‖ …(33) if 𝑘 selected large enough greater than 𝜌 𝑡 , then 𝑉 𝑡 ‖𝑀 𝑞 ‖‖𝑘 ‖‖𝑆‖ …(34) which implies that: 𝑉 𝑡 0 …(35) as a result the stability of the controlled system in (1) with the proposed control law in (11) is guaranteed. 5. simulation results in this section, the performance and robustness of the proposed control method is tested by applying it on the two link robotic arm. moreover, the proposed method is compared with the standard ctc method. additionally, integral absolute value error (𝐼𝐴𝐸) performance index is used to examine the tracking error performances in this comparison that can be expressed as follows: 𝐼𝐴𝐸 |𝑒 𝑡 |𝑑𝑡 …(36) the dynamic model of two link robotic manipulator is [21]: 𝜏 𝜏 𝐴 𝐴 𝐴 𝐴 𝑞 𝑞 2𝑏𝑞 𝑧𝑞 𝑏𝑞 0 𝑞 𝑞 𝑣 𝑞 𝑣 𝑞 𝑝 𝑠𝑔𝑛 𝑞 𝑝 𝑠𝑔𝑛 𝑞 𝐺 𝐺 …(37) with 𝐴 𝑚 𝑙 𝑚 𝑙 𝑙 2𝑙 𝑙 𝑐𝑜𝑠 𝑞 𝐴 𝑚 𝑙 𝑙 𝑐𝑜𝑠 𝑞 𝑙 𝐴 𝑚 𝑙 𝑏 2𝑚 𝑙 𝑙 𝑠𝑖𝑛 𝑞 𝑧 𝑚 𝑙 𝑙 𝑠𝑖𝑛 𝑞 𝐺 𝑚 𝐿 𝑔𝑐𝑜𝑠 𝑞 𝑚 𝑔 𝐿 𝑐𝑜𝑠 𝑞 𝑞 𝐿 𝑐𝑜𝑠 𝑞 𝐺 𝑚 𝑙 𝑔 𝑐𝑜𝑠 𝑞 𝑞 where 𝑞 and 𝑞 are angular positions, 𝜏 and 𝜏 are torques, 𝐿 and 𝐿 are lengths, 𝑚 and 𝑚 are masses, 𝑣 , and 𝑣 are coefficients of viscous friction, and 𝑝 and 𝑝 are coefficients of dynamic friction of link1and link2, respectively. the parameters of the robotic manipulator are selected as: 𝑚 10 𝑘𝑔 , 𝑚 2 𝑘𝑔 , 𝑙 1.1 m, 𝑙 0.8 m, 𝑃 𝑃 30 ,and 𝑉 𝑉 10 . the desired trajectory is 𝑞 𝑡 𝑞 𝑞 , where q sin 2πt …(38) 𝑞 sin 2πt …(39) the controller gains selected as follows: 𝑘 3, 𝑘 5, 𝑘 15.the robustness of the proposed method and standard ctc are checked by varying the parameters of the robotic system by 15% of their nominal. moreover, a sin 𝑡 disturbance signal is applied. at second 3, angular position and error in this position of robotic manipulators are shown in figures 1 and 2 for the proposed and ctc methods. these figures indicated faster response of the proposed method. the proposed method needs approximately 0.06 seconds until tracking error converges to zero. tables 1 and 2 list the 𝐼𝐴𝐸 for proposed control scheme and ctc methods for link1 and link2 respectively. maryam s. ahmed al-khwarizmi engineering journal, vol. 17, no. 3, p.p. 2228 (2021) 25 fig. 1. results for system uncertainty. these indices indicate that the performance of the prosed control method is better than standard ctc method in reduction tracking error. finally, it should be noted that all simulation results illustrate good robustness of proposed method against system uncertainty and external disturbance. table 1, performance of controllers under system uncertainty proposed ctc link 1 0.3464 2.1859 link 2 0.0419 1.7772 table 2 performance of controllers for disturbance rejection proposed ctc link 1 0.4679 2.7099 link 2 0.0485 2.2542 6. conclusion in this paper, a robust control method proposed for control a robotic manipulator. robotic manipulator is non-linear system, especially with the inability to represent the system perfectly due to the change in the parameters and the external disturbance. although, ctc is good control method, but it’s not robust to system uncertainties. this paper improves ctc method by adding a new robust term 0 1 2 3 4 5 -3 -2 -1 0 1 time(s) p os iti on tr ac ki ng o f l in k 1 ideal position proposed ctc 0 1 2 3 4 5 -1.5 -1 -0.5 0 0.5 1 1.5 time(s) p os iti on tr ac ki ng o f l in k 2 ideal position proposed ctc 0 1 2 3 4 5 -10 -5 0 5 10 time(s) s pe ed tr ac ki ng o f l in k 1 ideal speed proposed ctc 0 1 2 3 4 5 -10 -5 0 5 10 time(s) s pe ed tr ac ki ng o f l in k 2 ideal speed proposed ctc maryam s. ahmed al-khwarizmi engineering journal, vol. 17, no. 3, p.p. 2228 (2021) 26 fig. 2. results for disturbance rejection. moreover, lyapunov theorem stability has been used to approve stability of the proposed control method. it was concluded from the simulation results that there was a significant improvement in the performance of the proposed control in response to external disturbance and uncertainties in parameters of robotic manipulator. in future work, reinforcement learning can be used to select the optimal gains for the proposed controller parameters. moreover, the proposed algorithm can be tested in the real robotic manipulator. 7. references [1] a. mary, t. kara and a. miry, “inverse kinematics solution for robotic manipulators based on fuzzy logic and pd control”, alsadiq international conference on multidisciplinary in it and communication techniques science and applications(aicmitcsa), vol.pp.160-165, 2016. [2] a. kashyap and d. parhi, “particle swarm optimization aided pid gait controller design for a humanoid robot”, isa transaction, vol. 114, pp.306-330, 2020. [3] i. carlucho and g. acosta, “an adaptive deep reinforcement learning approach for mimo pid control”, isa transactions, vol.102, pp.280-249, 2020. [4] [4] x. yin, l. pan and s. cai, “robust adaptive fuzzy sliding mode trajectory tracking control for serial robotic manipulators”, robotics and computerintegrated manufacturing, vol. 72, pp. 101884, 2021. [5] a. mary and t. kara,” robust proportional control for trajectory tracking of a nonlinear robotic manipulator: lmi optimization approach”, arabian journal for science and engineering, vol. 41, pp. 50275036, 2016. [6] x. wu and y. huang, “adaptive fractionalorder non-singular terminal sliding mode control based on fuzzy wavelet neural networks for omnidirectional mobile robot manipulator”, isa transactions, vol. 115, 2021. [7] z. chen, x.yang and x. liu, “rbfnn-based non-singular fast terminal sliding mode control for robotic manipulators including actuator dynamics”, neurocomputing, vol. 362, pp. 72-92, 2019. [8] t. kara and a. mary,” robust trajectory tracking control of robotic manipulators based on model-free pid-smc approach” journal of engineering research, vol. 6, pp. 170-188, 2018. [9] t. kara and a. mary,” adaptive pd-smc for nonlinear robotic manipulator tracking 0 1 2 3 4 5 -1.5 -1 -0.5 0 0.5 1 1.5 time(s) p os iti on tr ac ki ng o f l in k 2 ideal position proposed ctc 0 1 2 3 4 5 -10 -5 0 5 10 time(s) s pe ed tr ac ki ng o f l in k 1 ideal speed proposed ctc 0 1 2 3 4 5 -10 -5 0 5 10 time(s) s pe ed tr ac ki ng o f l in k 2 ideal speed proposed ctc 0 1 2 3 4 5 -3 -2 -1 0 1 time(s) p os iti on tr ac ki ng o f l in k 1 ideal position proposed ctc maryam s. ahmed al-khwarizmi engineering journal, vol. 17, no. 3, p.p. 2228 (2021) 27 control” studies in informatics and control, vol. 26, pp. 49-58, 2017. [10] th. costa, f. lara-molina, a. junior and e. taketa,”robust h∞ computed torque control for manipulators”, ieee latin america transactions, vol. 16, pp. 398-407, 2018. [11] m. alwan, hassan and r. zaid hikmat,” motion control of three links robot manipulator (open chain) with spherical wrist”, al-khwarizmi engineering journal 15(2) ,13-23. 2019. [12] c. chen, c. zhang, t. hu, h. ni1, and w. luo,“model-assisted extended state observerbased computed torque control for trajectory tracking of uncertain robotic manipulator systems”, international journal of advanced robotic systems, vol. 15, pp. 1-12, 2018. ) 2021( 2228 صفحة ، 3العدد ، 17المجلد الهندسية الخوارزمي جلةم مريم صادق احمد 28 التحكم المتين في متحكم عزم دوران ذراع االنسان االلي ***هشام حسن جاسم **علي حسين مري احمد* مريم صادق *،**،***قسم هندسة الميكاترونكس/ كلية الهندسة الخوارزمي/ جامعة بغداد maryamsadeq97@gmail.com :البريد االلكتروني* alimary76@kecbu.uobaghdad.edu.iq :البريد االلكتروني** mschisham@gmail.com :البريد االلكتروني*** الصةالخ ثل نظام يدرس هذا البحث السيطرة على ذراع روبوت حيث تم إقتراح بناء منظومة سيطرة باالعتماد على طرق السيطرة الذكية. إذ إن ذراع الروبوت تم uncertaintyال خطيا وخاصة مع عدم القدرة على تمثيل النظام بشكل مثالي بسبب ازعاجات الحمل واإلخطاء التي تحصل عند نمذجة النظام وهو مايسمى system وهذا من خالل تحسين تحكم عزم الدورانctcاستخدمت نظرية, lyapunov للحصول على استقرارية النظام. و تم اختبار أداء المتحكم المقترح مقترحة ومتانتها والحصول متحكم عزم الدوران المحسوب التقليدي, حيث توضح نتيجة المحاكاة قوة الطريقة الومقارنتها مع matlab simulink بواسطه على تتبع مسار جيد وفق االداء الطلوب. this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 20, no. 4, december (2024), pp. 25-37 cuo/zno nanocomposite biosynthesis approach using eucalyptus leaves for photodegradation of tetracycline marwa s. ameer1, mohammed a. atiya2*, ahmed k. hassan3, abdelmalik milad shakorfow4, najah al mhanna5 1,2department of biochemical engineering, al-khwarizmi college of engineering, university of baghdad, baghdad, iraq 3environment, water, and renewable energy directorate, ministry of science and technology, baghdad, iraq 4elmergib university, libya 5german university of technology in oman, oman *corresponding author’s e-mail: atiya@kecbu.uobaghdad.edu.iq (received 24 may 2024; revised 5 july 2024; accepted 11 august 2024; published 1 december 2024) https://doi.org/10.22153/kej.2024.08.003 abstract in this study, the photocatalytic degradation of tetracycline (tc), which is responsible for water pollution, was investigated in an aqueous solution by using two types of nanoparticles (nps) based on green synthesis of zno nps and cuo nps as photocatalysts. eucalyptus plant extract was chosen as a good reductant and capping agent because of its costeffectiveness, nontoxic characteristics and ease of usage. different molar ratios of cu:zn (1:3, 1:6, 1:9 and 1:12) were prepared, and then these ratios were evaluated to select the effective ratio for removing tc. the 1:6 ratio demonstrated the best photocatalytic performance, degrading 72.15% of tc at the zno/cuo nanocomposite (nc) dose of 0.5 g/l, an initial concentration of 10 mg/l, ph 7, an agitation speed of 300 rpm, a temperature of 25 °c, uv intensities of 15 w/m2 and a contact time of 180 min. the synthesis of ncs was characterised using different analysis methods. cuo/zno characteristics were investigated using several analytical techniques, including ftir, fesem, edax, afm, bet and zeta potential analysis. the np’s structure, morphology, thermal behaviour, chemical composition and optical properties were analysed. the fesem images verified that the (1:6) cuo/zno nps calcined and not calcined, with sizes of 13.92 and 26.73 nm, respectively, were crystalline and spherical. the quantity of tc degradation by metal oxide ncs was investigated using uv–vis spectroscopy. this method is sustainable and environmentally benign because it synthesises both nps from plant sources. these hybrid nanoparticles may be used to treat other pharmaceuticals that are hazardous to reduce pollution in water. keywords: cuo/zno nanoparticles; eucalyptus; green synthesis; photocatalyst process; tetracycline (tc) 1. introduction human and veterinary medications are one of the leading sources of contamination in natural water systems owing to their widespread usage nowadays. many antibiotics are released into rivers together with medical waste and wastewater from pharmaceutical plants. antibiotics in aquatic environments are a substantial source of environmental contamination [1]. conventional water and wastewater treatment plants cannot entirely remove antibiotics and other pharmaceutical compounds. as a result, antibiotics are released into the environment through wastewater, exposing humans, aquatic species and plants to them. for these reasons, future research must focus on developing suitable treatment systems that may be integrated into water and wastewater facilities [2]. tetracycline (tc) antibiotics are the second most commonly employed antibiotics globally, producing and using antibiotics widely utilised today to treat various infectious disorders. this antibiotic’s presence in the environment harms human health and ecological function [3]. in 2002, the worldwide usage of antibiotics was between mailto:atiya@kecbu.uobaghdad.edu.iq https://doi.org/10.22153/kej.2024.08.003 marwa s. ameer al-khwarizmi engineering journal, vol. 20, no.4, p.p. 2537 (2024) 26 100,000 and 200,000 tons per year. by 2015, this amount had risen to 34.8 billion, representing a significant increase of 65% since 2000. it is projected that by 2020, the consumption of antibiotics will reach 4.5 trillion doses [4]. hospitals, pharmaceutical industries, and livestock contribute to the buildup of tc in wastewater systems [5]. domestic wastewater has a low content of tcs, namely, 1 mg l−1, whereas hospital wastewater has a considerably larger concentration of tcs, specifically 100 mg l−1 [6, 7]. thus, an effective technique to eliminate harmful compounds is necessary [3]. various methods were used to remove pollutants, such as physical [8], chemical and biological procedures like adsorption [9], membrane process [10], chemical oxidation [11], ozonation [12], ultrasound [13] and membrane reactors to eliminate antibiotic residues, including tc [14]. advanced oxidation processes (aops) are effective methods of degrading harmful and biodegradable contaminants in aquatic environments [3], as shown in figure 1. aops, including photolysis, ozonation, fenton and photofenton processes and the oxidation of antibiotics in the presence of ozone/uv/hydrogen peroxide, primarily include the transformation and release of oxidised products. fig. 1 advanced processes for the removal of tc. nanotechnologies have recently become important in eradicating environmental contaminants. nano-adsorbents exhibit better adsorption capacity than traditional adsorbents due to their larger specific surface area and enhanced selectivity. this is achieved through precise surface modification of the nanomaterial to target impurities in particular [15]. by utilising plant extracts or bio-organisms, green synthesis is a simple substitute for chemical synthesis. it offers several advantages over chemical processes, including scaling up systems whilst ensuring economic viability, environmental friendliness and operational efficiency [16]. photocatalytic remediation for removing antibiotic contaminants from water is an extremely promising method. the process can potentially convert organic contaminants in effluent into innocuous molecules whilst being environmentally sustainable [17]. photodegradation, when combined with the application of chemical compounds like tio2 and zno suspensions, is a very promising technology for rapidly degrading tc. this method has been extensively studied and shown to be effective in previous research [13, 23, 24]. the advantageous properties and wide-ranging uses of metal oxide nanoparticles (nps) have garnered significant interest across various disciplines in recent decades. zno and cuo are two examples of nps [20]. zno and cuo nps are widely used because they have unique chemical, physical and mechanical properties, including low melting point, large surface area, excellent structural stability, rapid diffusion and high surface energy [21]. zno is classified as an n-type semiconductor because of its notable direct energy band gap measuring 3.37 ev. meanwhile, cuo is categorised as a p-type semiconductor owing to its comparatively narrower band gap of 2.5 ev. the incorporation of zno nps into the cuo matrix was effectively carried out through environmentally sustainable synthesis methods, leading to a band gap reduction of 1.45 electron volts relative to the initial constituents [22]. cuo/zno ncs were formed using biological systems, particularly extracts obtained from diverse plant constituents (including leaves, seeds, pith and bark) and biomass generated from bacteria, algae and fungi. innovative precursor substances were produced in the structure of biogenic molecules [23]. recent proposals suggest that for the synthesis of cuo/zno ncs, leaf extracts are a superior alternative to currently available biological systems. this technology promotes environmental sustainability and reduces costs by eliminating the requirements for biological material collection, storage, manipulation and disposal [24]. various techniques are employed to characterise the composites, including energy dispersive x-ray spectroscopy (edax), fourier transform infrared (ftir) spectroscopy, atomic force microscopy (afm), brunauer–emmett–teller (bet) method, zeta potential (zp) and field-emission scanning electron microscopy (fesem). eucalyptus serves as a reliable source of bioactive compounds. the ecological methodology produces nps by utilising terpenoids, phenols and their derivatives. moreover, marwa s. ameer al-khwarizmi engineering journal, vol. 20, no.4, p.p. 2537 (2024) 27 this plant is easily accessible in most nations [15]. the well-known perennial tree eucalyptus globulus is utilised in numerous industries, including construction, biology, medicine, flavouring, fragrance and essential oil production [25]. in the present study, cuo/zno ncs were produced by blending the two components in different ratios by utilising an extract obtained from the foliage of the eucalyptus plant. these ratios were evaluated to determine the best ratio for eliminating tc from water. 2. experimental procedures 2.1. chemicals and reagents the target adsorbate tc was provided by the state enterprise for drug industries and medical appliances in samara, iraq, table 1 outlines tc’s primary characteristics. the eucalyptus leaves used were picked up from a yard at the university of baghdad, iraq. znso4.7h2o with a purity of > 98.0% and cuso4·5h2o with a purity of > 99% were purchased from cdh company, india, and alpha chemicals, india, respectively. naoh was acquired from cdh company. absolute ethanol was purchased from carlo erba’s company. table 1. properties of tetracycline 2.2. leaf extract preparation cuo/zno nanocrystals were manufactured using the same process as described in a previous research [26], with some modifications. the leaves of the eucalyptus plant were collected from the grounds of university of baghdad. they were cleaned many times with distilled water and then dried for 12 h at 50 °c in an oven. once completely dried and able to be crushed, the leaves were ground into a powder and sieved using a 63 µm sieve. subsequently, 15 g of eucalyptus leaf powder was introduced into 200 ml of deionised water and heated with magnetic stirring for 30 min at 85 °c ± 5 °c, as shown in figure 2. the resultant extract was chilled and subsequently allowed to reach room temperature. it was then filtered using vacuum filtration using whitman filter paper number 2 to remove suspended leaves. the resulting solution was enclosed in a glass bottle and stored in a refrigerator at 4 °c for use in the next experiments. fig. 2. diagram of eucalyptus extract preparation 2.3. synthesis of cuo/zno nanocomposites (ncs) green synthesis of zno/cuo ncs was conducted by altering the prescribed ratios for this experiment. table 2 lists the mass of cuso4·5h2o and znso4.7h2o in the molar ratios of cu/zn as (1:3), (1:6), (1:9) and (1:12). marwa s. ameer al-khwarizmi engineering journal, vol. 20, no.4, p.p. 2537 (2024) 28 table 2. weight parameters of copper sulphate and zinc sulphate salts in synthesising cuo/zno heterojunctions. salt molar ratio of cu/zn 1:3 1:6 1:9 1:12 cuso4.5h2o 0.6884 0.3888 0.2709 0.2078 znso4.7h2o 2.3116 2.6112 2.7291 2.7922 in accordance with basit et al. [27], with minimal adjustments by utilising a chosen ratio, solid znso4 and cuso4 salts were added separately to 100 ml of deionised water and magnetically agitated at 150 rpm for 10 min, respectively. once the salts were fully dissolved, the contaminants were eliminated by employing a 0.45 μm membrane filter. subsequently, a solution of znso4 and cuso4 was combined for 15 min at 70 °c with continuous stirring. the eucalyptus extract was incrementally introduced into the zinc/copper salt solution, and the resulting combination was agitated at 70 °c. the solution’s ph was modified to 10 by gradually adding a solution of naoh (1 m). as a result, the solution’s colour changed from dark brown to dark yellow, indicating the formation of cuo/zno ncs during the reduction process. the resultant mixture was continuously agitated and heated at 70 °c for 3 h. after the reaction, the precipitate of ncs was obtained using vacuum filtering and promptly subjected to five washes with distilled water and three washes with ethanol to eliminate all contaminants and the remaining salt from the items. the precipitates were dehydrated in an oven at 60 °c for 10 h and transformed into a fine powder by using a mortar and pestle. the calcination process was carried out at 500 °c for a duration of 3 h by using a muffle furnace. afterwards, the substance was left to passively cool to ambient temperature. 2.4. characterisation of (cuo-zno) ncs various techniques were utilised to determine the surface area, structure, dimensions, size and chemical composition of cuo/zno ncs. the crystalline structure and degree of phase purity of the cuo/zno (ncs) synthesised via xrd were determined using a phillips x’pert diffractometer. the “tescan-vega3 model” was employed to acquire sem images of the nps, which were subsequently analysed to ascertain their structure, particle size and shape. an energy-dispersive xray spectroscopy edax analysis was conducted to determine the chemical compositions. the surface area of cuo/zno ncs was determined via bet test using a device model (tristar ii plus version 2.03, usa). ftir analysis (shimadzu, japan) was employed to identify the functional groups present during the process. zeta potential analysis was utilised to evaluate the nps’ stability. afm (tt-2, usa) was utilised to determine the morphology and surface texture of cuo/zno ncs. 2.5. analytical method a calibration curve was constructed for the standard antibiotic tetracaine tc solution before commencing the experiments to determine the maximum wavelength (λmax) and establish the equation relating absorbance to concentration. according to figure 3, the λmax of tc was seen at 276 and 357 nm. the wavelength 357 nm is the most significant one for tc because it yields the highest absorbance [2]. the calibration plot of tc at the maximum wavelength of this antibiotic is shown in figure 5. the percentage degradation efficiency (de %) was estimated using the following formula, where co and ct are the concentrations of tc at zero and time t, respectively, (mg. l−1) [26]: de% = co−ct co × 100 …(1) marwa s. ameer al-khwarizmi engineering journal, vol. 20, no.4, p.p. 2537 (2024) 29 fig. 3. (a) uv–vis analysis for various concentrations of tc solutions. (b) calibration plot at λmax 357 nm. 2.6. photocatalytic activity the effectiveness of zno/cuo ncs in photocatalysis was assessed by measuring the photodegradation of tc under different molar ratios of cu to zn (1:3, 1:6, 1:9 and 1:12), as shown in table 1. this analysis aimed to identify the optimal molar ratio of cu/zn. the experimental parameters for the removal of tc for each ratio were used, with the catalyst doses of zno/cuo ncs at 0.5 g and a ph of 7. to achieve this, 1000 ml of a 10 ppm tc solution was mixed with the catalyst dose amounts in a 1 l beaker and continuously stirred at 300 rpm at room temperature. the mixture was left in the dark for 30 min to ensure adsorption–desorption equilibrium [28, 29]. photocatalysis experiments were conducted utilising a semi-piolet-scale photoreactor that has been designed and is powered by 24 uv-a lamps with the following dimensions: 30 cm in length, 2.2 cm in width and a maximal wavelength peak of 365 nm. afterwards, the experiments were conducted for 180 min; the λmax of tc chosen from the calibration curve was 357 nm. throughout the assays, 10 ml of the specimens was collected at consistent time intervals (0, 5, 10, 15, 20, 25, 30, 45, 60, 90, 120 and 180 min) and filtered through a 0.45 m filter. the concentration of tc was measured using a shimadzu-japan uv-vis spectrophotometer. the elimination rate was computed by employing equation 1. 3. results and discussion 3.1 fe-sem and edax analyses figures 4 (a) and (b) show the fesem images of calcined cuo/zno ncs and non-calcined ncs. the x-rays in sem can be used to identify a sample’s elemental composition by using edax. the sem images showed that the cuo/zno ncs have a semi-spherical morphology, with some degree of aggregation attributed to the presence of biomolecules from eucalyptus leaf extract that cap these ncs [30]. in figure 4 (a), the synthesised ncs exhibited porous and spherical morphology, with an average diameter of ~14 nm. the sem image indicates a randomly distributed sphere and few nanorods with an average diameter of ~27 nm, as shown in figure 4 (b). figure 5 (a) and (b) show the edax spectrum, atomic distribution and elemental mapping topology of cuo/zno ncs with a molar ratio of cu to zn of 1:6, and the samples were calcined and not calcined. the intense peaks of zn, cu and o in the calcined cuo/zno ncs indicated the place of atomic distribution on the surface and the chemical composition. the weight percentages of zn, cu and o were 57.78 wt%, 0.20 wt%, and 42.02 wt%, respectively. by contrast, the intense peaks in the cuo/zno ncs without calcination showed weight percentages of 90.68 wt% for zn, 0.10 wt% for cu and 9.22 wt% for o. small particles exhibit a large surface area due to their high surface-to-volume ratio. consequently, a higher quantity of atoms was present on the surface of the particle than the atoms located on the inside. surface atoms possess unoccupied valence or dangling bonds, rendering them highly reactive for the adsorption of other species or interaction with surrounding surface atoms, leading to the formation of particle clusters [31]. marwa s. ameer al-khwarizmi engineering journal, vol. 20, no.4, p.p. 2537 (2024) 30 fig. 4. sem image of cuo/zno ncs: (a) calcined and (b) not calcined (a) (b) fig. 5. edax analysis of cuo/zno ncs: (a) calcined and (b) not calcined 3.2 afm the size and morphology of cuo/zno ncs were assessed using afm, which measures the force of contact between the tip and the surface. figure 6 presents a three-dimensional representation of an afm image, showcasing a uniform and smooth surface of nps exhibiting marwa s. ameer al-khwarizmi engineering journal, vol. 20, no.4, p.p. 2537 (2024) 31 diverse sizes and compositions. the surface roughness of the nps improves their capacity to absorb ions of organic pollutants [32]. the synthesised nps were round and triangular. the average sizes were 76.95 nm for the calcined cuo/zno ncs with a molar ratio of 1:6 and 88.61 nm for the ncs without calcination according to afm figures 6 (a) and (b). fig. 6. atomic force microscopic (afm) characterisation for cuo/zno ncs: (a) calcined and (b) not calcined. 3.3 ftir spectroscopy ftir spectroscopy (shimadzu, japan) was applied to determine the state of the catalysts and provide details on their functional groups and chemical bonds for all the four molar ratios of calcined cuo/zno ncs. the analysis used a midinfrared spectrum ranging from 400 cm−1 to 4000 cm−1, as shown in figure 7. the peaks seen at 3618 and 3406 cm−1 are a result of the o–h stretching vibration, indicating the presence of polyphenol groups and supporting the existence of different capping and reduced bioactive molecules in the eucalyptus extract [30]. phenolic compounds may be the cause of the stabilising process of nps. the existence of a narrow absorption band indicates the occurrence of aromatic c−c stretching within the range of 865‒870 cm−1. the stretching modes of c– o seen at 1057 and 1188 cm−1 are present in the spectra of zno/cuo ncs and ascribed to the presence of adsorbed c=o on the surface of zno/cuo ncs due to the incomplete breakdown of the acetate group [25]. the presence of cuo/zno ncs was demonstrated by the 413 and 517 cm−1 peaks for all the four molar ratios of calcined cuo/zno ncs. fig. 7. fourier transform infrared (ftir) spectra of cuo/zno ncs with different molar ratios of cu: zn from 1:3 to 1:12 marwa s. ameer al-khwarizmi engineering journal, vol. 20, no.4, p.p. 2537 (2024) 32 3.4 powder xrd xrd was used to characterise the crystalline structure and degree of phase purity of the synthesised cuo/zno ncs. the compositional analyses or phase identification for all samples were performed using xpert-pro software. the peaks in the xrd of the molar ratio of cu:zn at 1:3, 1:6, 1:9 and 1:12 were searched and then matched with the standard diffractograms given in the joint committee for powder diffraction standards (jcpds) database. the xrd patterns in figure 8 showed that all the samples exhibited almost identical major diffraction peaks, suggesting that the crystal structures of the four samples, namely 1:3, 1:6, 1:9 and 1:12, were identical [29]. the former represents the standard xrd of hexagonally crystalline zno, whereas the latter represents monoclinic cuo. the diffraction peaks for each of the molar ratios of cu:zn from 1:3 to 1:12 were located at (100), (002), (101), (102), (110), (103), (200), (112), (20 1), (004) and (202), with its corresponding 2θ values of ≈ 31.83°, 34.49°, 36.32°, 47.60°, 56.67°, 66.38°, 67.60°, 69.10°, 72.56° and 76.96°, respectively. these findings were in good agreement with the jcpds of 00-0361451 [28]. typical peaks appeared with the diffraction peaks of the cuo sample acquired at the 2θ values of 32.51, 38.71, 46.26, 61,53, 74.98 and 79.73, which are due to (110), (111), (−112), (−113), (004) and (023), respectively. these data were found to be the same as those reported in plans jcpds of 00-048-1548. the increase in the molar ratio of cu:zn from 1:3 to 1:12 resulted in a drop in cu content, which, in turn, reduced the strength of the distinctive diffraction peaks of cuo [33]. the product possesses a well-crystalline particle structure, as seen by the diffraction peaks that are narrow and robust [21]. fig. 8. xrd patterns of cuo/zno ncs with different molar ratios of cu:zn from 1:3 to 1:12 3.5 bet table (3) describes the surface area results of cuo/zno ncs obtained by the bet technique. the pore sizes of calcined and uncalcined cuo/zno ncs were 12.92151 and 11.63821 nm, respectively. according to the international union of pure and applied chemistry (iupac), a pore size in the 2– 50 nm range indicates mesoporous, which enhances the catalytic activities due to the enhancement of the diffusion of materials [34]. table 3. bet parameters for cuo/zno nps: (a) calcined and (b) not calcined (a) (b) 3.6 zp analysis measuring zeta potential is an essential method for ensuring the stability of particles. nps demonstrate stability because of their increased zeta potential. a significant negative value proves the repulsion between particles, preventing the agglomeration of ncs and verifying their stability. conversely, their diminished potential encourages and promotes flocculation. as shown in figures 9 (a) and (b), the high negative values at −37.61and −29.01 mv acquired by zeta potential analysis revealed that excellent stability of cuo/zno ncs with and without calcination, respectively. the catalyst’s stability is attributed to the application of a polyphenol coating derived from eucalyptus leaves onto the surface of the ncs [35]. parameter value bet (m2/g) 25.9477 pore size (nm) 12.92151 pore volume (cm3/g) 0.083821 parameter value bet (m2/g) 49.7492 pore size (nm) 11.63821 pore volume (cm3/g) 0.144748 marwa s. ameer al-khwarizmi engineering journal, vol. 20, no.4, p.p. 2537 (2024) 33 (a) (b) fig. 9. zeta potential of (cuo/zno) ncs: (a) calcined and (b) and not calcined 4. photocatalytic efficiency the photocatalytic performance of a greenproduced cuo/zno ncs was evaluated by studying the degradation of tc in a visible annular-type photoreactor under uv light irradiation. exposing the specimen to light initiates the real study because the semiconducting zno absorbs the photon of energy from the cuo nc, which has a higher bandgap. as seen in eqs. (1) and (2), visible light photons are expected to stimulate the valence electrons of cuo due to their small bandgap energy. this process creates a hole in the valence band (vb) of cuo, which then moves towards zno, causing reduction processes and the production of superoxide ions, as in eq. (3). therefore, the electrons created by light can only transfer from the conduction band (cb) of cuo to the conduction band of zno due to the difference in their cb energy levels [33]. the transfer of electrons from the conduction band of zno to the valence band of cuo is relatively unlikely. instead, the presence of a hole enables oxidation reactions to occur, resulting in the generation of hydroxyl radical •oh and hydroperoxyl h2o2 species, as in eq. (5). these species exhibit a high level of effectiveness in breaking down organic contaminants [36]. radical oxidation species, such as •o2− and •oh, oxidise pollutants (tc) into degradation products, as in eqs. (7) and (8). thus, the heterojunction created by mixing zno and cuo limits the recombination of photogenerated pairs, allowing for improved oxidative species formation [25]. the inclusion of cuo reduces electron/hole recombination and enhances the formation of active radicals, resulting in a higher rate of organic pollutant degradation [31]. zno + hν (visible light) → zno (𝑒𝐶𝐵 − +ℎ𝑉𝐵 + ) …(1) cuo + hν (visible light) → cuo (𝑒𝐶𝐵 − +ℎ𝑉𝐵 + ) …(2) 𝑂2 + 𝑒− →• 𝑂2 − )superoxide radicals ( …(3) • 𝑂2 − + h2o → ho2• ) hydroperoxy( +oh– …(4) ho2 • +h2o → h2o2 + •oh) hydroxyl radicals( …(5) h2o + h+ → •oh + h+ …(6) •o2 − + organic pollutants → degraded products …(7) •oh + organic pollutants → degraded products …(8) the photodegradation of tc in the presence of as-prepared nps was examined under uv-a light, and the extent of degradation was measured in terms of the absorbance of the tc solution by using a uv– vis spectrophotometer after certain intervals of time for 180 min [37]. figure 10 showcases the results of the degradation studies, revealing an increase in tc degradation with increasing irradiation time. experiments were conducted to test the efficiency of different ratios of cu to zn (1:3, 1:6, 1:9 and 1:12). the results indicated that the ratio of 1:6 had the best degree of removal efficacy amongst all ratios when the cuo/zno nc dose, ph, initial concentration, temperature, agitation speed and time were set to 0.5 g.l−1, 7, 10 mg.l−1, 25 °c, 300 rpm and 180 min, respectively. the degradation rate increased with increasing amounts of copper in 1:6 ratio, but when copper decreased in 1:9 and 1:12 ratios, the photocatalytic activity decreased due to the higher bandgap for zno nps than for cuo/zno ncs. this finding indicated that an increase in cuo amount in ncs resulted in a decrease in the energy bandgap, which improves visible light harvesting and decreases photocatalytic activity. still, in the 1:3 ratio, the photocatalytic activity decreased as the amount of copper increased. a higher percentage of copper covered the zno surface, reducing light absorption [33, 38]. the absorbance spectra of tc clearly showed that the tc solution was degraded by 47.8%, 72.1%, 53.08% and 53.9% after 180 min in the presence of green-synthesized cuo/zno ncs. marwa s. ameer al-khwarizmi engineering journal, vol. 20, no.4, p.p. 2537 (2024) 34 fig. 10. tc removal for the ratios of cu to zn (1:3, 1:6, 1:9 and 1:12) at cuo/zno nc dose, ph, initial concentration, temperature, agitation speed and time of 0.5 g.l−1, 7, 10 mg.l−1, 25 °c, 300 rpm and 180 min, respectively. 5. conclusion this study presents a cost-effective and environmentally friendly solution to the water purification problem. eucalyptus leaf extract was used for capping and reducing agents at four molar ratios of copper to zinc for the biosynthesis of cuo/zno ncs. these ratios were characterised using ftir, fe-sem, edax, afm, xrd, bet and zeta potential. the calcined cuo/zno ncs and the sphere and a few nanorods of the noncalcined cuo/zno ncs demonstrated average diameters of 14 and 27 nm, respectively, and surface areas of 25.95 and 49.75 m2/g, respectively. during the process setup, different molar ratios (1:3, 1:6, 1:9 and 1:12) of cuo/zno ncs were used to degrade tc through photocatalytic reactions. the results showed the 1:6 ratio was better at photocatalytic drug removal than the other molar ratios. it was able to remove 72.15% of the drug at an nc dose of 0.5 g.l−1, ph 7, an initial concentration of 10 mg.l−1, a temperature of 25 °c and a contact time of 180 minutes. acknowledgement the authors express their profound gratitude to the department of biochemical engineering at al khwarizmi college of engineering, university of baghdad, iraq, and nahrain university for providing facilities for the characterisation of nps. the authors would also like to thank the environment and water directorate of the ministry of science and technology in iraq for providing all the required facilities and dr benyamin laboratories, tehran university, north karegar ave, tehran, iran, for their remarkable scientific support. references [1] m. h. mahdi, t. j. mohammed, and j. a. alnajar, “removal of tetracycline antibiotic from wastewater by fenton oxidation process,” eng. technol. j, vol. 39, pp. 260–267, 2021. 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(2024) 25-37، صفحة 4، العدد20مجلة الخوارزمي الهندسية المجلدمروة سعد عبد االمير 37 بتوس للتحلل يكاليوباستخدام أوراق ال cuo/znoنهج التخليق الحيوي للمركبات النانوية الضوئي للتتراسيكلين ،3أحمد خضير حسان ،* 2محمد عبد عطية السراج ، 1األمير سعد عبد مروة 5نجاح المحنا ، 4عبد المالك ميالد شاكر العراق ،بغداد، جامعة بغداد ،كلية الهندسة الخوارزمي ،قسم الهندسة الكيمياوية الحيوية 2،1 العراق ،بغداد ،مديرية البيئة والمياه والطاقة المتجددة، وزارة العلوم والتكنولوجيا 3 جامعة المرقيب / ليبيا 4 الجامعة األلمانية للتكنولوجيا في عمان/عمان 5 atiya@kecbu.uobaghdad.edu.iq* البريد اإللكتروني: خالصةال على ، المسؤول عن تلوث المياه، في محلول مائي باستخدام نوعين من الجسيمات النانوية (tc) في هذه الدراسة، تم دراسة التحلل الضوئي للتتراسيكلين تم اختيار مستخلص . كمحفز ضوئي (cuo nps)( وجسيمات أوكسيد النحاس النانوية zno npsاألخضر لجسيمات أوكسيد الزنك النانوية ) خليقأساس الت من ناحية أخرى، يتم تحضير بسبب خصائصه الفعالة من حيث التكلفة وكونه مادة غير سامة وسهولة استخدامه.كاليبتوس كعامل اختزال وتغطية جيدة يونبات ال أظهرت أفضل نسبة (tc) (، ومن ثم يتم تقييم هذه النسب الختيار النسبة الفعالة إلزالة الدواء1:12، 1:9، 1:6، 1:3نسب مولية مختلفة من النحاس: الزنك ) جم، zno/cuo ncs 0.5 عند جرعات المحفز tc % من72.15( أفضل أداء تحفيزي ضوئي، حيث أدت إلى تحلل 1:6كسيد الزنك )وكسيد النحاس/أوأل 15ة درجة مئوية، وكثافة األشعة فوق البنفسجي 25حرارة دورة في الدقيقة، ودرجة 300، وسرعة الخلط 7، ودرجة الحموضة مجم/لتر 10والتركيز األولي ft-باستخدام العديد من التقنيات التحليلية، بما في ذلك التحليل المحتمل cuo/zno . تمت دراسة خصائص الجسيمات النانويةدقيقة 180والوقت 2واط / م ir وfe-sem وedax وafm وbet و zeta ،والسلوك الحراري، والتركيب الكيميائي، وتشكلهاقامت الدراسة بتحليل بنية الجسيمات النانوية ، نانومتر، على التوالي، 26.73نانومتر و 13.92ة بحجم نة وغير المكلسنالمكلس) cuo/zno ncs 1:6أن ) fe-sem لخصائص البصرية. أثبتت صوروا بيئيًا ألنها سليمةهذه الطريقة مستدامة وباستخدام التحليل الطيفي لألشعة فوق البنفسجية. ncs بواسطة tc كانت بلورية وكروية. تم فحص كمية تحلل الدواء ألخرى الخطرة من أجل تقوم بتركيب كال الجزيئات النانوية من مصادر نباتية. يمكن استخدام هذه الجسيمات النانوية الهجينة لمعالجة المستحضرات الصيدالنية ا تقليل التلوث في المياه. mailto:atiya@kecbu.uobaghdad.edu.iq https://doi.org/10.22153/kej.2024.08.003 _66-88_ ikhlase m.fayed dr. ikhlase m.fayed/al-khwarizmi engineering journal, vol.3, no.3 pp(2007) ٦٦ effects of internal acoustic excitation on the improvement of airfoil performance dr. ikhlase m.fayed department of mechanical engineering university of technology (received 3 april 2007; accepted11 julay2007) abstract: the effect of internal acoustic excitation on the leading-edge, separated boundary layers and the aerodynamic performance of naca23015 cross section airfoil are examined as a function of excitation location with ranging frequency range (50-400) hz of the introduced acoustic. tests are separately conducted in two sections, open type wind tunnels at the reynolds number of 3.3x105 for measurement at angle of attack (0, 3, 6, 9 &12) deg. and 3x104 for the visualization at angle of attack (12) deg. based on the airfoil chord. results indicated that the excitation frequency and the excitation location are the key parameters to alter the flow properties and thus to improve the aerodynamic performance. the most effective excitation frequency is found to be equal to the shear layer instability frequency and on excitation location close to the separation point. moreover, the lift is increased and drag reduced dramatically. the corresponding boundary layers are visualized to be reattached to the surface. key words: internal excitation , separation control , naca 1. introduction: there are many circumstances in practice where flow separation plays a major role in determining the flow characteristics. for instance, a wing stall phenomenon may occur when airplane flies at a high angle of attack. it is of great interest to alleviate these problems by applying artificial means so as to suppress and control the flow separation. they founded that sound at particular frequencies and intensities could change the transition process of boundary layer. the flow field exhibited different characteristic and the momentum exchange is enhanced due to the introduction of the acoustic waves. in accordance with this observation the control of flow with vertical structures using excitation techniques has been studied extensively in resent years. one of the techniques is called the external acoustic excitation in which the sound is radiated onto the wall from a source outside the flow system. this technique has been applied by zaman et al. [1987] which studied the effect of external acoustic excitation about a stall airfoil (lrn-(1)-1007). he founded that a significant improvement in lift was achieved because the tunnel resonance could strongly enhance the out comes, especially for some cases in which a large amplitude was required. yarusevych et al. [2006] studied experimentally the effect of external al-khwarizmi engineering journal al-khwarizmi engineering journal, vol.3, no.2, pp 66-88 (2007) dr. ikhlase m.fayed/al-khwarizmi engineering journal, vol.3, no.3 pp(2007) ٦٧ acoustic excitation on the wake structure and performance of naca0025 airfoil .wind tunnel experiments were carried out for three reynolds number (57,100,150)x103 and three angle of attack (0,5,10) degree with operating velocity of 2.8 m/s the results establish that external acoustic excitation became effective only when the excitation frequency was close to the tunnel resonance frequency. further more the external excitation required high sound pressure level in order achieves satisfactory results. to overcome those draw backs an internal excitation technique is used in which the sound is emanated from opening on the wall surface. this technique has been intensively studied by hsiao et al. [1990], chang et al. [1992], and hsiao et al. [1997] for an airfoil (633-018) performance. addition study done by naveh et al. [1998] for an airfoil naca0015. they indicated that the technique can significantly enhance aerodynamic performance at a relatively modest expense. the main purpose of this paper is further to examine the effectiveness of the internal acoustically pulsing excitation technique on aerodynamic performance of an airfoil (23015) at angle of attack (0,3,6,9,12). the flow visualization technique will also be carried out to investigate the vertical structure patterns over the airfoil. 2. experimental facilities: the investigations were conducted on a suction open-type, subsonic wind tunnel with a 305x305 mm test section ( see fig.1a) . a contraction section with contraction ratio 9:1 and five finemeshed screens are used for managing the free stream turbulence intensity. downstream of the working section a diffuser leads to an axial flow fan which is driven by a 506 kw three phase a.c. motor. the flow is controlled by a butterfly valve before exhausting to atmosphere through a silencer. the tunnel rests on tubular steel supports. the free stream velocity in the test section was 33.15 m/s. the free stream turbulence intensity of the flow is less than (1.25%) alan and harper [1966]. the flow visualization study is carried out in smoke tunnel with working section (100 mm deep) x (180 mm wide) x (240 mm high) fine meshed screens are installed in the settling chamber ( see fig.1b). smoke line are generated in a wind tunnel by introducing smoke through a small pipe placed in front of a test model, so that the flow around the model is made visible. photograph systems are used to analyze the flow structure. four geometrically naca23015 airfoil models made of warinshed teak wood are employed in this study. the specification of naca 23015 has been shown in table (1) . models a&b airfoil of 150mm chord and 305 mm in span was used in subsonic wind tunnel for pressure measurement and models c&d airfoil of 150mm chord and 100mm in span are used for the flow visualization study. as shown in fig. (1c). for measurement of pressure distribution twenty four pressure tape with 1 mm diameter were installed along the upper ( 16 taps ) and lower surface ( 8 taps )of airfoil in the mid span of model a&b ( see fig.1d) . four narrow slots of 1mm in width and 100 mm in length, located in the mid span are manufactured to omit acoustic wave. the location of slots, from leading edge for models a&c will be at 6.5% chord while models b&d will be at 11.5% chord. the acoustic generated by loud speaker was funneled into interior of model by 10 mm diameter copper tube. the loud speaker is driven by a power amplifier with a variable frequency function generator. the mean velocity measurement of the test section was made by a pitot-static tube. the static pressure distribution along the solid body of airfoil is measured by multitube manometer to study the aerodynamic dr. ikhlase m.fayed/al-khwarizmi engineering journal, vol.3, no.3 pp(2007) ٦٨ characteristic and the effect of the value when they are excited. the measurement is repeated four times to check the measurement reading then calculated the error measurement (6%). 3. result and discussions: effect of excitation on pressure distributions: the pressure coefficient normalized by the free stream properties, is defined as 2 2 1 ∞ ∞− = u pp cp ρ and is used to describe the pressure distributions in the present study. the surface pressure distributions with and without excitation of the two cases done, one at excitation of 11.5% chord from leading edge at the angles of attack ( 9 & 12) deg. are presented in figs.(2&3) respectively while other at excitation of 6% chord for the angle of attack (9 &12) deg. are presented in fig.(4&5). it clearly reveals that there is significant change in pressure after the sound introduced. however for angle of attack higher than (9) deg. a significant (suction peak) occurs near the leading edge on the upper surface. the larger suction peak area will result in a substantial contribution to the lift for the enhancement of the flow mixing and momentum transport due to internal excitation produces a suction peak at the leading edge of the upper surface airfoil. the suction peaks result in an increase of lift. when the flow excited at the frequency of (50 hz) a suction peak is formed, the pressure recovery steadily persists all the way down stream to the trailing edge on the upper surface. steeper suction peak is formed when the excitation is increased to 150 as shown in figs. (3c & 5c) at angle of attack (12)deg. effect of excitation frequency on lift: it has been know that the pressure distribution is sensitive to the disturbance frequency of the acoustic. the lift and drag coefficient have bee defined as : c xdcpcpcn celowersurfaceuppersurfa )( 1 0 −−= ∫ ∫= cy cy c ydcpcc / / cl= cn cos α -cc sin α cd= cn sin α +cc cos α figs.( 6&7) show the variation of the lift coefficient with angle of attack (312)deg. at an excitation frequency ranging from (50 to 400 hz). results clearly indicate the sensitivity of the flow. when the angle of attack less than 8 deg., the lift increase is negligible. it then becomes significant as the angle of attack increases. when the excitation location at 11.5% chord the increase in lift is around 10-20% when the flow is excited within the frequency range from 50 to 150 hz with peak at frequency 150 hz at angle of attack (12)deg. as shown in fig.(6). while for the excitation location 6% was around 1528.5% for the same angle of attack as shown in fig.(7). the contribution from the excitation at other frequency still exits, but it is not so significant. the lift coefficient is improved when the excitation frequency was lockedin to the shear layer, instability frequency of the separated boundary layer and frequency around the natural separation point. effect of excitation location on lift: two slots located at 6% and 11.5% chord for the acoustic emission are ………………….. (1) dr. ikhlase m.fayed/al-khwarizmi engineering journal, vol.3, no.3 pp(2007) ٦٩ investigated respectively. fig. (8) depicts the dependence of the lift on the excitation location at ranging angle of attack (312)deg. with frequency 150 hz. it can be seen that excitation location 6% chord has most significant improvement in lift. in other words the effectiveness of the boundary-layer control with internal excitation strongly depends on the excitation location and excitation at apposition close to separation point is most effective so when the flow is excited near the separation point at the favorable frequency the flow separation is suppressed and maximum lift is increased. flow visualization: the effect of excitation on lift generation is further substantiated by carrying out flow visualization study as depicted in fig.(9) for the flow with & without excitation at the angle of attack 12 deg. for the location of frequency 6% &11.5% chord. the leading edge separation is clearly revealed when the flow is unexcited fig. (9a). however when the flow is excited at the shear layer instability frequency of (150 hz) figs. (9, b&c) the separated boundary layer in manifested to be reattached to the boundary of the airfoil surface. the reattachment boundary layer will certainly ensure the lift recovery. also the wake region is narrow due to the boundary reattachment. the excitation location at 6% chord has narrow wake region less than 11.5% chord fig.(9c), narrow wake with a smaller profile defect indicates a less momentum loss which ensure smaller drag coefficient (higher lift to drag ratio) as seen in fig. (10) we can conclude that by applying the acoustics internally for the flow excitation at the shear layer instability frequency the double advantages that is higher lift and marrow wake region will assume the higher value of lift to drag ratio. 4. conclusions: the study of internal acoustic excitation technique to improve the aerodynamic performance (control flow separation) passing an airfoil is conducted in a suction open type subsonic wind tunnel and a smoke wind tunnel. the technique is quite promising and effective in improving the aerodynamic performance. the enhancement of the flow mixing and momentum transport due to internal excitation produces a suction peak at the leading edge of the upper surface airfoil. the suction peak results in an increase of lift and narrow wake. consequently the aerodynamic efficiency (lift-to-drag ratio) is substantially improved when the excitation frequency is locked-in to the shear layer, instability frequency around the natural separation point. the excitation point is most effective and the aerodynamic efficiency is strikingly improved. table (1) the specification of naca 23015. upper surface lower surface x mm y mm x mm y mm 0 0 0 0 1.875 5.01 1.875 2.31 3.75 6.66 3.75 3.375 7.5 8.835 7.5 4.56 11.25 10.35 11.25 5.415 15 11.46 15 6.135 22.5 12.78 22.5 7.26 dr. ikhlase m.fayed/al-khwarizmi engineering journal, vol.3, no.3 pp(2007) ٧٠ 30 13.38 30 8.115 37.5 13.62 37.5 8.67 45 13.575 45 8.94 60 12.885 60 8.88 75 11.61 75 8.25 90 9.915 90 7.215 105 7.875 105 5.865 120 5.595 120 4.245 135 3.06 135 2.385 142.5 1.68 142.5 1.35 150 0 150 0 5. reference [1] k. b. m. q. zaman, a bar-sever& s. m. mangalam, "effect of acoustic excitation on the flow over a low-re airfoil" j-fluid mech, vol. 182, pp. 127 148, 1987. [2] yarusevych s., j. g. kawall & p.sullivan , “influence of acoustic excitation on airfoil performanc at low reynolds numbers”, j.fluids engineering, vol.128, 2006. [3] fei-bin hsiao, chin-fung liu, and jong-yaw shyut, "control of wall separated flow by internal acoustic excitation", aiaa journal, vol. 28, no. 8,1990. [4] r. c. change, f. b. hsiao, r. n. shyu, "forcing level effects of internal acoustic excitation on the improvement of airfoil performance", journal of aircraft, vol. 129, no. 5, sep. oct. 1992. [5] hsiao f. b., j. j. jihand and r. n. shyn, “the effect of acoustics on flow passing a high-aoa airfoil”, journal of sound and vibration, vol. 199, no.2, 1997. [6] naveh t, seifert a, wygnanski i. “sweep effect on parameters governing control of separation by periodic excitation”, alaa journal, vol. 35, no.3, 1998. [7] alan. p.j. and harper, “ low speed wind tunnel testing ” john willey and sons. int. 1966. 6. nomenclature c chord m cc free coefficient in x direction -- cl lift coefficient -- cn free coefficient in x direction -- cd section drag coefficient -- cp pressure coefficient -- f frequency hz p static pressure n/m2 p∞ static pressure in free stream n/m2 u∞ free stream velocity m/s x distance along surface airfoil -- y perpendicular distance on airfoil surface -- ρ fluid density kg/m3 dr. ikhlase m.fayed/al-khwarizmi engineering journal, vol.3, no.3 pp(2007) ٧١ dr. ikhlase m.fayed/al-khwarizmi engineering journal, vol.3, no.3 pp(2007) ٧٢ dr. ikhlase m.fayed/al-khwarizmi engineering journal, vol.3, no.3 pp(2007) ٧٣ dr. ikhlase m.fayed/al-khwarizmi engineering journal, vol.3, no.3 pp(2007) ٧٤ dr. ikhlase m.fayed/al-khwarizmi engineering journal, vol.3, no.3 pp(2007) ٧٥ dr. ikhlase m.fayed/al-khwarizmi engineering journal, vol.3, no.3 pp(2007) ٧٦ dr. ikhlase m.fayed/al-khwarizmi engineering journal, vol.3, no.3 pp(2007) ٧٧ dr. ikhlase m.fayed/al-khwarizmi engineering journal, vol.3, no.3 pp(2007) ٧٨ dr. ikhlase m.fayed/al-khwarizmi engineering journal, vol.3, no.3 pp(2007) ٧٩ dr. ikhlase m.fayed/al-khwarizmi engineering journal, vol.3, no.3 pp(2007) ٨٠ dr. ikhlase m.fayed/al-khwarizmi engineering journal, vol.3, no.3 pp(2007) ٨١ dr. ikhlase m.fayed/al-khwarizmi engineering journal, vol.3, no.3 pp(2007) ٨٢ dr. ikhlase m.fayed/al-khwarizmi engineering journal, vol.3, no.3 pp(2007) ٨٣ dr. ikhlase m.fayed/al-khwarizmi engineering journal, vol.3, no.3 pp(2007) ٨٤ dr. ikhlase m.fayed/al-khwarizmi engineering journal, vol.3, no.3 pp(2007) ٨٥ dr. ikhlase m.fayed/al-khwarizmi engineering journal, vol.3, no.3 pp(2007) ٨٦ dr. ikhlase m.fayed/al-khwarizmi engineering journal, vol.3, no.3 pp(2007) ٨٧ dr. ikhlase m.fayed/al-khwarizmi engineering journal, vol.3, no.3 pp(2007) ٨٨ تأثیر اإلثارة الصوتیة الداخلیة على تحسین الخصائص الدیناھوائیة على الجنیح اخالص محمد فیاض.د قسم ھندسة المكائن والمعدات الجامعة التكنولوجیة :الخالصة درس تأثیر اإلثارة الصوتیة الداخلیة على الحافة األمامیة للجنح ، انفصال الطبقة المتاخمة و أداء ) . ٥٠٤٠٠(بداللة موقع اإلثارة لمدى من الترددات الصوتیة ) naca23015(لمقطع جنح الدیناھوائیة أجریت مجموعة من التجارب ، المجموعة األولى أجریت في نفق ھوائي مفتوح عند عدد رینولدز محسوب على المجموعة الثانیة ). o١٢ ، ٩ 0o،3o،6 o ، o (لقیاس توزیع الضغط لزوایا ھجوم (3.3x105)أساس الوتر أظھرت النتائج ان تردد و موقع االثارة ھما ) . o١٢(أجریت في نفق الدخان إلظھار الجریان لزاویة ھجوم ان أفضل تردد اثارة وجد . العامالن االساسیان في تغیر خصائص الجریان و تحسین خصائص الدیناھوائیة طة االنفصال إضافة الى ذلك زیادة في الرفع و انخفاض في بالقرب من تردد العتبة مع موقع إثارة قریب من نق .كما لوحظ في إظھار الجریان ان الطبقة المتاخمة تعید تالمسھا مع السطح. الكبح this is an open access article under the cc by license : al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 21, no. 2, june, (2025), pp. 42-52 autonomous path planning and obstacle avoidance of a wheeled mobile robot via grey wolf optimisation zahraa a. abdulla1*, and nabil h hadi2 1 department of mechanical engineering, college of engineering, university of baghdad, baghdad, iraq 2 department of aeronautical engineering, college of engineering, university of baghdad, baghdad, iraq corresponding author’s email: zahraa.abdullah2003d@coeng.uobaghdad.edu.iq (received 19 may 2024; revised 2 august 2024; accepted 1 september 2024; published 1 march 2025) https://doi.org/10.22153/kej.2025.09.003 abstract the aim of this study was to implement and compare obstacle avoidance for an autonomous wheeled mobile robot (wmr) via the grey wolf optimisation (gwo) algorithm and the artificial bee colony (abc) algorithm. the study was conducted via three scenarios, each designed to test the performance of the algorithm under different conditions, considering fixed and moving circular obstacles in the surrounding environment. gwo was used to determine the most efficient, shortest and safest path for the wmr from the starting point to the target point. the results showed that the gwo outperformed the abc. the gwo also enabled the wmr to avoid obstacles faster by 11.8%, 2.8% and 4.6% and with distances shorter by 1.42%, 2.2% and 1.97% for the three scenarios, respectively. keywords: bees algorithm; grey wolf optimisation; wheeled mobile robot. 1. introduction path planning is extensively utilised in autonomous robot navigation to calculate the most effective path between the starting point (sp) and the destination or target point (tp) whilst avoiding obstacles [1,2]. path planning for optimising path length is an important part of mobile robot navigation. this optimisation challenge involves determining a path that minimises distance whilst conforming to constraints such as collision avoidance in a particular environment. over time, extensive research has been conducted to overcome this problem, classifying techniques and algorithms as stochastic or deterministic approaches [1]. linear programming and newton’s method are deterministic algorithms that ignore randomness in their mathematical foundation. by contrast, stochastic approaches are unconstrained by specific mathematical properties; thus, they can attain global optimal solutions across various objective functions. these stochastic algorithms, which are frequently inspired by natural behaviours observed in creatures such as birds, ants, bees and fish, have gained popularity since the 1980s [2]. numerous algorithms, such as firefly algorithms [3], ant colony optimisation [4], particle swarm optimisation (pso) [7,8] and grey wolf optimisation (gwo) [9,10], are widely used. gwo is a recently discovered optimisation method used in various relevant disciplines; it closely resembles the hierarchical structure and hunting methods of grey wolf packs, optimising solutions through actions such as tracking, surrounding and pouncing. in contrast to classic algorithms such as pso and artificial bee colony (abc), the gwo algorithm is notable for its simplicity; it needs relatively few parameters and follows clear implementation principles. path planning remains a critical topic in mobile robot research, with the goal of determining collision-free pathways between defined start and target points in a known environment [9]. this problem is further separated into two parts: static path planning, in which obstacles remain fixed, and dynamic path planning, in which obstacle positions change over time. several techniques and algorithms have been suggested to address the path mailto:zahraa.abdullah2003d@coeng.uobaghdad.edu.iq mailto:zahraa.abdullah2003d@coeng.uobaghdad.edu.iq https://doi.org/10.22153/kej.2025.09.003 zahraa a. abdullah al-khwarizmi engineering journal, vol. 21, no.2, pp. 42-52 (2025) 43 planning issue. a relatively new method [10] uses abc algorithms to plan collision-free trajectories for mobile robots. this methodology reportedly produces the best results and is suitable for real-time applications. the convergence and stochastic stability of the pso algorithm were analysed [11]. the research was differentiated from traditional pso by investigating the statistical distributions of the pso parameters. a comparative analysis [12] was conducted to compare the standard and upgraded versions of the bacterial foraging optimisation algorithm. this investigation resulted in the identification of optimal trajectories. chaotic sequences [13] were utilised to change parameters and improve optimisation capabilities. enhanced qlearning algorithms [14] were introduced to expedite convergence in difficult situations. these algorithms incorporate plant pollination techniques for initialising q values and optimising path planning via a variable called the ‘limit’. finally, a comparative analysis [15] was implemented to evaluate the effectiveness of chaotic pso in comparison with typical pso algorithms in the task of calculating minimal distances whilst navigating around obstacles in static environments. the results demonstrated that chaotic pso was more efficient than normal pso in generating shorter paths and achieving faster convergence. this study utilised the classical abc and gwo algorithms to compare their achievements in terms of identifying the shortest path and achieving the fastest time to reach the target point. the results demonstrated that the gwo algorithm had higher efficiency. 2. problem formulation one of the fundamental phases in path planning is environment modelling. the wheeled mobile robot (wmr) is represented as a particle with a radius (r) in a 2d cartesian space (x, y) with static barriers in the environment, each with a radius (r) (figure 1). the point (0,0) in the bottom left corner of the environment symbolises the robot’s sp. the primary goal of applying obstacle avoidance algorithms in local path planning is to generate an online optimal path between the sp and tp without colliding with any obstacles in the surroundings. three assumptions are considered in this research. in the first assumption, obstacles are depicted as round shapes. in the second assumption, all obstacles are increased by the robot’s radius to ensure safe navigation when moving from the sp to the tp; however, in the third assumption, the type of wmr is nonholonomic. fig. 1. original and expanded obstacle boundaries. 3. performance criteria 3.1. short path the shortest path is achieved in planning paths by minimising the distance between the sp and the tp. the mathematical expression used to calculate the function’s objective is as follows: 𝐹1 = 𝑑(𝑝𝑖(𝑡), 𝑝(𝑁)) …(1) where 𝑑 denotes the euclidean distance, and 𝑝𝑖(𝑡) refers to a set of midpoints the optimisation algorithm selects on the basis of a specified criterion. this criterion requires that these points have the shortest distance to the tp, denoted by 𝑝(𝑁). the shortest path distance (𝑆𝑃𝐷) can be determined in the following manner. 𝑆𝑃𝐷 = ∑ √(𝑋𝑝𝑖(𝑡 + 1) − 𝑋𝑝𝑖(𝑡)) 2 + (𝑌𝑝𝑖(𝑡 + 1) − 𝑌𝑝𝑖(𝑡)) 2𝑁−1 𝑖=1 …(2) where (t) is the simulation time. 3.2. path smoothness the goal of obtaining path smoothness is to reduce the angular difference between the present and proposed locations (figure 2). the mathematical formula used to illustrate path smoothness is given by equations (3) to (5) [16]. fig. 2. example of path smoothness zahraa a. abdullah al-khwarizmi engineering journal, vol. 21, no.2, pp. 42-52 (2025) 44 𝐹2 = ∑|𝜃(𝑝𝑖(𝑡), 𝑝𝑖(𝑡 + 1))𝜃(𝑝𝑖(𝑡), 𝑝(𝑁))| 𝑁−1 𝑖=1 …(3) 𝜃(𝑝𝑖(𝑡), 𝑝𝑖(𝑡 + 1)) = tan−1 𝑌𝑝𝑖(𝑡+1)−𝑌𝑝𝑖(𝑡) 𝑋𝑝𝑖(𝑡+1)−𝑋𝑝𝑖(𝑡) …(4) 𝜃(𝑝𝑖(𝑡), 𝑝(𝑁)) = tan−1 𝑌𝑝(𝑁)−𝑌𝑝𝑖(𝑡) 𝑋𝑝(𝑁)−𝑋𝑝𝑖(𝑡) …(5) the rating of fitness is calculated by combining two objectives, one of which is the weight: 𝐹(𝑋, 𝑌) = 𝑤1 ∙ 𝐹1(𝑋, 𝑌) + 𝑤2 ∙ 𝐹2(𝑋, 𝑌) …(6) the values 𝑤1 and 𝑤2 indicate the relative significance of the weights applied to each objective. their individual values must satisfy the following criteria: 𝑤 = 𝑤1 + 𝑤2 …(7) which can explain the following total fitness function: 𝑓𝑖𝑡𝑛𝑒𝑠𝑠 = 1 𝐹(𝑋,𝑌)+𝑒 …(8) typically, the factor ′𝑒′ prevents division by zero and is often set to a small value (e.g. 0.001). each iteration aims to select an optimal solution by balancing the two performance objectives outlined in equations (1) to (3). amongst the four candidate locations, p2 is optimal for the current iteration ‘t’, and p3 is optimal for the next iteration ‘(t + 1)’ (figure 3). however, for the subsequent iteration ‘(t + 2)’, whilst the distances for p1 and p4 may be short, the angles are larger. thus, p2 strikes a balance between these two objectives. this approach continues iteratively until a globally optimal solution is found. fig. 3. planning the path with point selection [16] 3.3. moving obstacles each obstacle might vary its position with each time step. here, obstacles are assumed to move linearly with constant speed (𝑣0𝑏𝑠) and direction (𝜃𝑜𝑏𝑠) according to the following equations: 𝑋𝑜𝑏𝑠2 = 𝑋𝑜𝑏𝑠1 + 𝑣0𝑏𝑠 ∙ 𝑐𝑜𝑠 𝜃𝑜𝑏𝑠 ∙ 𝑡 …(9) 𝑌𝑜𝑏𝑠2 = 𝑌𝑜𝑏𝑠1 + 𝑣0𝑏𝑠 ∙ 𝑠𝑖𝑛 𝜃𝑜𝑏𝑠 ∙ 𝑡 …(10) 4. swarm intelligence swarm intelligence (si) is a branch of study that is based on the collective behaviour of social creatures such as ants, bees, wolves and birds. the goal is to create an artificial algorithm that imitates the characteristics of these natural swarms to address challenging issues. si algorithms frequently use a population of simple agents or particles interacting with one another and their surroundings to identify optimal solutions. these methods effectively solve optimisation, clustering and routing problems. here, two optimisation methods, namely, gwo and abc, are utilised to address the path-planning challenge of wmrs. 4.1. abc algorithm the abc algorithm belongs to the si domain and is influenced by the natural activities of honeybees. karboga introduced abc optimisation in 2005 to address complicated situations[17]. according to the abc framework, bees are classified into three types: employed, scout and onlooker. employed bees, up to half of the bee population, are principally responsible for finding new food sources and communicating this knowledge to onlooker bees. after receiving information from employed bees, onlooker bees exploit these food sources. a food source depleted by exploitation is marked for replenishment, and a scout bee takes on this responsibility. the basic steps of the abc algorithm are as follows [19,20]: zahraa a. abdullah al-khwarizmi engineering journal, vol. 21, no.2, pp. 42-52 (2025) 45 4.1.1. population initialisation a set of sn individuals is generated randomly. sn indicates the number of solutions, which is equivalent to the number of food sourcesxi = (xi1, xi2,… , xid). the population searches for positions of food sources. this process continues until the maximum number of cycles is reached. each solution can be generated according to equation (11) [18]. 𝑥𝑖,𝑗 = 𝑥𝑚𝑖𝑛,𝑗 + 𝑟𝑎𝑛𝑑(0,1)(𝑥𝑚𝑎𝑥,𝑗 − 𝑥𝑚𝑖𝑛,𝑗) …(11) where sn: number of food sources (equivalent to the number of employed or onlooker bees) d: number of optimisation parameters j = 1,2,… . . d і = 1,2… . sn xmax,j =upper bounds of xi,j xmin,j = lower bounds of xi,j rand(0,1) = real number in the interval [0, 1] 4.1.2 employed bee stage at this stage, a new solution 𝑣𝑖,𝑗 = {𝑣𝑖,1,𝑣𝑖,2, … . . 𝑣𝑖,𝐷} is constructed for food source 𝑥𝑖, with only one parameter being updated by 𝑣𝑖,𝑗 = 𝑥𝑖,𝑗 + ∅𝑖,𝑗(𝑥𝑖,𝑗 − 𝑥𝑘,𝑗) …(12) where 𝑘 ∈ [1,2,3…… . 𝑆𝑁] and 𝑗 ∈, 𝑘 ≠i, ∅𝑖,𝑗 denotes a real number selected randomly from the interval [−1, 1]. each worker bee subsequently utilised the greedy method to calculate the difference in nectar quantity between (𝑥𝑖,𝑗) and (𝑣𝑖,𝑗). when the quantity of nectar in (𝑣𝑖,𝑗) is greater than that of (xi,j), (𝑣𝑖,𝑗) is substituted for (𝑥𝑖,𝑗), and the resulting population number is 𝑣𝑖,𝑗. if (𝑥𝑖,𝑗) changes, then counter (𝑖) is incremented by 1. 𝑓𝑖𝑡𝑛𝑒𝑠𝑠𝑖 = { 1 + 𝑎𝑏𝑠(𝑓(𝑥𝑖)), 𝑓(𝑥𝑖) < 0 1 1+𝑓(𝑥𝑖) , 𝑓(𝑥𝑖) ≥ 0 …(13) where 𝑓(𝑥𝑖) is the objective value for the solution 𝑥𝑖 calculated via fitness equation (8). each onlooker bee’s principal function is to determine the food’s location by applying the probability (pi) [19]: 𝑝𝑖 = 𝑓𝑖𝑡𝑛𝑒𝑠𝑠𝑖 ∑ 𝑓𝑖𝑡𝑛𝑒𝑠𝑠𝑖 𝑆𝑁 𝑖=1 …(14) the (𝑓𝑖𝑡𝑛𝑒𝑠𝑠𝑖) value of the solution 𝑥𝑖 is directly proportional to the quantity of nectar present in that particular food source. once the onlooker bees have selected the food positions, new positions for the food are generated 𝑣𝑖,𝑗 via equation (12). the bees then employ a similar greedy strategy to assess these new positions. 4.1.3 scout bee stage the abandonment counter (count i) of each solution 𝑥 𝑖 is evaluated in relation to the limit. the algorithm maintains a constant limit throughout its execution. the employed bees, which cannot improve their self-solution through the limit, are considered the worst. the bees are then dispatched as scout bees, in accordance with equation (11), to arbitrarily investigate new food sources after discarding the poorest food source. 4.2 gwo algorithm according to research, grey wolves, a type of canid animal, play an important role as apex predators in the ecological food chain, indicating that they are top predators. these creatures greatly prefer communal living, which involves a complex social hierarchy amongst their packs (figure 4). the α wolf is at the top of the hierarchy, functioning as the pack’s leader and being in charge of controlling group dynamics and making key decisions. the β wolves are located below the α wolf and are responsible for helping them whilst being prepared to take on leadership positions if necessary. the δ wolves are on the third level, obediently carrying out orders from higher-ranking commanders and doing jobs such as surveillance and reconnaissance. finally, the omega ω wolves at the bottom level are largely focused on preserving peaceful interactions within the pack [23,[21]. fig. 4. grey wolf class scheme the gwo algorithm completes one cycle in four stages: hierarchical division, exploration, surrounding and attacking. initially, the wolf population is separated into hierarchies depending on individual fitness levels, symbolised by the letters α, β, δ and ω. the algorithm’s optimisation phase concentrates on each generation’s top three optimal solutions. the mathematical models that define grey wolves’ exploration and tracking zahraa a. abdullah al-khwarizmi engineering journal, vol. 21, no.2, pp. 42-52 (2025) 46 behaviours are outlined below: grey wolves browse the search space to locate probable solutions, simulating their hunting behaviour via a mathematical model. surrounding: when grey wolves locate a prospective candidate solution or prey, they work together to surround it, producing an encirclement pattern to increase the chances of catching it. attack: finally, after successfully surrounding the prey, grey wolves select the most appropriate individual within the surroundings to start an attack, with the goal of increasing the population’s overall fitness. figure 5 shows solid circles representing the positions of wolves labelled α, β, δ and ω in a 2d plane. the symbol p denotes the prey’s relative position. following the three major processes of grey wolf hunting, i.e. approaching, surrounding and attacking the prey, the α wolf, accompanied by β and δ wolves, leads the pursuit once the prey is located. amongst the wolves, α, β and δ are closest to the prey, and their placements influence the direction of prey p. when the fitness of the grey wolves is assessed, optimal, good and suboptimal options can be identified. the positions of the other wolves are based on those of α, β and δ. each wolf in the pack indicates a possible option for the population. the location of the α wolf represents the optimal answer, and the positions of β and δ reflect good and inferior solutions. 𝑥⃗⃗ indicates a grey wolf’s current position vector. 𝑥𝛼⃗⃗ ⃗⃗ , 𝑥𝛽⃗⃗⃗⃗ and 𝑥𝛿⃗⃗⃗⃗ represent the three best individuals. the vectors 𝐶1 ⃗⃗⃗⃗ , 𝐶2 ⃗⃗⃗⃗ and 𝐶3 ⃗⃗⃗⃗ are random, and 𝐷𝛼 ⃗⃗⃗⃗ ⃗ and 𝐷𝛿 ⃗⃗⃗⃗ ⃗ represent the distances between the candidate wolf and the three best individuals. the vectors 𝑥1 ⃗⃗ ⃗⃗ , 𝑥2,⃗⃗ ⃗⃗ and 𝑥3⃗⃗⃗⃗ represent the candidate wolves’ step lengths towards the three best individuals. figure 5 shows the execution concept for the gwo algorithm. fig. 5. schematic of gwo principles the mathematical framework for how grey wolves look for and track prey is expressed as follows: �⃗⃗� = |𝐶 ⋅ 𝑥 𝑝 (𝑡) − �⃑�(𝑡)| …(15) 𝑥 (𝑡 + 1) = 𝑥 𝑝(𝑡) − 𝐴 ⋅ �⃗⃗� …(16) where �⃗⃗� represents the vector reflecting the distance between the gray wolf and its prey. the prey position vector is 𝑥 𝑝, the grey wolf position vector is �⃑�, the iteration number is t, and the coefficient vectors are 𝐴 and 𝐶 . the coefficient vectors 𝐴 and 𝐶⃗⃗ ⃗ can be defined as follows: 𝐴 = 2𝑎 ⋅ 𝑟 1 − 𝑎 …(17) 𝐶 = 2𝑟 2 …(18) the convergence factor, denoted by 𝑎 , decreases gradually from 2 to 0 with each iteration. the values of 𝑟 1 and 𝑟 2 are random numbers ranging from 0 to 1. when grey wolves find their prey whilst searching, they encircle it using α, β and δ as guides. however, because the specific location of the optimal prey in the abstract space is unknown, the top three best solutions identified thus far are preserved to define positions and motivate other individuals to alter their search positions to mimic the true behaviour of grey wolves. the mathematical model for this method is given by the following: 𝐷𝛼 ⃗⃗⃗⃗ ⃗ = |𝐶 1 ⋅ 𝑥 𝛼 − �⃑�| …(19) 𝐷𝛽 ⃗⃗⃗⃗ ⃗ = |𝐶 2 ⋅ 𝑥 𝛽 − �⃑�| …(20) 𝐷𝛿 ⃗⃗⃗⃗ ⃗ = |𝐶 3 ⋅ 𝑥 𝛿 − �⃑�| …(21) 𝑥1⃗⃗⃗⃗ = 𝑥 𝛼 − 𝐴 1 ⋅ �⃗⃗� 𝛼 …(22) 𝑥2⃗⃗⃗⃗ = 𝑥 𝛽 − 𝐴 2 ⋅ �⃗⃗� 𝛽 …(23) 𝑥3⃗⃗⃗⃗ = 𝑥 𝛿 − 𝐴 3 ⋅ �⃗⃗� 𝛿 …(24) 𝑥(𝑡 + 1) = 𝑥1⃗⃗ ⃗⃗ +𝑥2⃗⃗ ⃗⃗ +𝑥3 ⃗⃗ ⃗⃗ ⃗⃗ ⃗⃗ ⃗ 3 …(25) 5. suggested algorithm this section covers the two primary subjects of the path planning method for nonholonomic wmrs. the subjects under discussion include the development of feasible paths and the detection of obstacles. 5.1. feasible path generation at each iteration (t), the abc and gwo provide multiple solutions. the task is to select the most suitable via-points from the set of possible options. the choice of via-points is contingent upon formulating the objective function specified in equation (6). this process continues until the wmr reaches its target point. zahraa a. abdullah al-khwarizmi engineering journal, vol. 21, no.2, pp. 42-52 (2025) 47 5.2 procedure for obstacle detection sensing is accomplished by attaching 12 virtual sensors around the mobile robot. these sensors have equal distances, with each sensor covering an angle range of 30° and having a certain sensing range (sr) value (figure 6). in the research design, the sr is 0.4 m. fig. 6. mobile robot sensor deployment the sensory vector (𝑣𝑠) is employed as a binary vector to indicate whether or not environmental impediments are present. each of the 12 binary values that comprise sv= [s (1), s (2)..., s (12)] represents a deployed sensor. the equation s(1) =s (3) =s (4) =logic ‘1’ might be used to identify obstacles within the dr range of s1, s3 and s4 and the da range of s4. otherwise, logic ‘0’ means to release space in the surrounding surroundings. here, two environmental impediments are assumed. if the first obstacle is expressed as sv=[1 0 1 1 0 0 0 0 0 0 0 0], then it evidently falls within the immediate scope of s1. however, the second obstacle is located between s3 and s4. this process is completed by determining the geometrical distance between the obstacle and the location of the wmr, and the following formula is used. 𝑑(𝑀𝑅𝑝𝑜𝑠, 𝑂𝑏𝑠𝑡𝑝𝑜𝑠) …(26) 6. results and discussion three scenarios were tested to evaluate the performance of the implemented algorithms via matlab and graphical user interface programming. in the first scenario, six fixed obstacles are present in the surrounding environment. in the second scenario, three moving obstacles are present in the surrounding environment. in the third scenario, five obstacles, three fixed and two moving obstacles, are present. the setting had dimensions of 10 m × 10 m. the parameters consisted of a population size of 0.5 and a wmr radius of 0.15 m, with the sp at (0,0), the tp at (10,10) m, a wmr velocity of 0.2 m/s and a total of 100 iterations. each scenario was replicated ten times to evaluate the efficacy of the two algorithms. 6.1. first scenario six fixed obstacles with three via points are employed. the details of the obstacles are shown in table 1. table 1. description of the obstacles in the first scenario obstacles centre (x, y) m radius (unit) m 1 (1,1) 0.2 2 (3,4) 0.25 3 (4,6) 0.4 4 (8,4) 0.3 5 (7,8) 0.2 6 (6,8) 0.4 fig. 7. optimal path suggested by abc (fixed obstacles) zahraa a. abdullah al-khwarizmi engineering journal, vol. 21, no.2, pp. 42-52 (2025) 48 fig. 8. optimal path suggested by gwo (fixed obstacles) on the basis of the presented plots, specifically figures 7 and 8, the path produced by the abc method has a length of 14.255 m. the computation time for generating this path is 27.0246 s. additionally, the via-points are located at coordinates (2, 2.435), (5.32, 5, 61) and (8, 8.122). by contrast, the gwo algorithm produces a path that has a length of 14.0541 m. the computation time for this approach is 24.0114 s. the more significant via-points are situated at coordinates (2.01, 1.6074), (5.02, 4.7808) and (7.988, 7.71). the analysis of the performance data from figures 7 and 8 reveal that the path produced by gwo is approximately 1.42% shorter and approximately 11.8% faster than that produced by abc. therefore, gwo outperforms abc because of the improvement in the control limit parameter in gwo. 6.2. second scenario three moving obstacles with two waypoints are implemented. the obstacle parameters are shown in table 2. table 2. description of the obstacles in the second scenario obstacles initial (x, y) m radius (unit) m 𝒗𝒐𝒃𝒔𝒕𝒂𝒄𝒍𝒆 (m/s) 𝜽𝒐𝒃𝒂𝒕𝒂𝒄𝒍𝒆 (degree) 1 (2,0) 0.2 0.01 90 2 (4,3) 0.4 0.05 150 3 (0,6) 0.3 0.01 270 (a) (b) fig. 9. optimal path suggested by abc (moving obstacles) (a) zahraa a. abdullah al-khwarizmi engineering journal, vol. 21, no.2, pp. 42-52 (2025) 49 (b) fig. 10. optimal path suggested by abc (moving obstacles) the robot starts its path from the sp at (0,0) and moves towards the tp at (10,10) m (figures 9(a) and 10(a)). figures 9(b) and 10(b) show where the robot decided to deviate from its initial path and instead used the abc and gwo algorithms to create new paths to avoid moving obstacles in the environment. the robot securely reaches the goal point (10 m × 10 m). the total length of the path from the sp to the tp in figure 9 is equal to 14.8913 m, and the computation time is 37.433 s. the positions of the more significant via-points are (3.21, 5.817) and (7.34, 8). the total path length from the sp to the tp in figure 10 is 14.566 m, and the computation time is 36.4 s. the positions of the more significant via-points are (3.02, 4.917) and (7.07, 7.866). the results showed that the optimised path generated by gwo was 2.2% shorter and 2.8% faster than that generated by abc. the gwo algorithm performs better than abc does, and the algorithm’s capacity to determine the quickest and shortest optimal path is enhanced. 6.3. third scenario five obstacles are considered. the third and fourth obstacles are moving, and the others are fixed with three via-points. the details of the obstacles are shown in table 3. table 3. description of the obstacles in the third scenario obstacles centre (x, y) m radius (unit) m 𝒗𝒐𝒃𝒔𝒕𝒂𝒄𝒍𝒆 (m/s) 𝜽𝒐𝒃𝒂𝒕𝒂𝒄𝒍𝒆 (degree) 1 (1,1) 0.4 ------------- 2 (2,3) 0.25 ------------- 3 (6,3) 0.3 0.05 60 4 (2,5) 0.25 0.01 90 5 (7,7) 0.35 ------------ fig. 11. robot and obstacle locations for the third scenario before traveling begins figure 11 shows the robot’s position and the fixed and moving obstacles before it begins moving to take the right path, which allows it to avoid obstacles and safely reach its target point. fig. 12. optimal path suggested by abc (fixed and moving obstacles) fig. 13. optimal path suggested by gwo (fixed and moving obstacles) zahraa a. abdullah al-khwarizmi engineering journal, vol. 21, no.2, pp. 42-52 (2025) 50 figures 12 and 13 show the paths produced by the abc and gwo methods. the path of the abc algorithm has a length of 14.7233 m. the computation time for the robot traveling is 27.8 s. additionally, the more significant via-points are located at coordinates (1.33, 3.07), (2.53, 4.029) and (7.17, 7.7381). by contrast, the gwo algorithm produces a path with a length of 14.4361 m. the computation time for this approach is 26.548 s. the more significant via-points are situated at coordinates (1.32, 3.13), (2.54, 4.17) and (7.18, 7.7761). the performance data shown in figures 12 and 13 reveal that the path produced by gwo is approximately 1.97% shorter and approximately 4.6% faster than that produced by abc. thus, gwo outperforms abc because of the improvement in the control limit parameter in gwo. 7. conclusion the abc or gwo algorithms are triggered to create a safe, smooth and faster alternative path to the tp. the gwo algorithm is compared with the classical abc algorithm in different scenarios to test how sufficiently each algorithm performs, and metrics involving the calculation time and path length are evaluated. the simulation results demonstrated that the ideal path produced by gwo is approximately 1.42% shorter and 11.8% faster than the path generated by abc in the initial scenario, which includes six fixed environmental obstacles. the second example has three moving obstacles in the environment. the gwo algorithm yields a path that is 2.2% shorter and 2.8% faster than the other paths. the third scenario has five obstacles, consisting of two moving obstacles and three fixed obstacles. furthermore, the gwo algorithm outperforms the abc algorithm by following a path that is 1.97% shorter and 4.6% faster than the other paths. references [1] k. heero, path planning and learning strategies for mobile robots in dynamic partially unknown environments. tartu university press, 2006. [2] h. chen, y. zhu, and k. hu, “adaptive bacterial foraging optimization. abstract and applied analysis,” abstr. appl. anal. https//doi. org/10.1155/2011/108269, 2011. [3] x.-s. yang, optimization techniques and applications with examples. john wiley & sons, 2018. [4] a. m. husain, s. m. sohail, and v. s. narwane, “path planning of material handling robot using ant colony optimization (aco) technique,” int. j. eng. res. appl., vol. 2, no. 5, pp. 1698–1701, 2012. [5] d. wang, d. tan, and l. liu, “particle swarm optimization algorithm: an overview,” soft comput., vol. 22, pp. 387–408, 2018. [6] h. zhangfang, f. chunyi, and l. yuan, “improved particle swarm optimization algorithm for mobile robot path planning,” comput. appl. res, vol. 38, pp. 3089–3092, 2021. [7] s. mirjalili, s. m. mirjalili, and a. lewis, “grey wolf optimizer,” adv. eng. softw., vol. 69, pp. 46–61, 2014. [8] j. cai, “non-linear grey wolf optimization algorithm based on tent mapping and elite gauss perturbation. comput,” eng. des, vol. 43, pp. 186–195, 2022. [9] m. j. mohamed and f. s. khoshaba, “enhanced genetic algorithm based on node codes for mobile robot path planning,” iraqi j. comput. commun. control eng., vol. 12, no. 2, pp. 69–80, 2012. [10] e. garcía-gonzalo and j. l. fernándezmartínez, “convergence and stochastic stability analysis of particle swarm optimization variants with generic parameter distributions,” appl. math. comput., vol. 249, pp. 286–302, 2014. [11] n. h. abbas and f. m. ali, “path planning of an autonomous mobile robot using enhanced bacterial foraging optimization algorithm,” alkhwarizmi eng. j., vol. 12, no. 4, pp. 26–35, 2016. [12] m. jasim mohamed and m. waad abbas, “enhanced ga for mobile robot path planning based on links among distributed nodes,” eng. technol. j., vol. 31, no. 1a, pp. 26–41, 2013. [13] e. s. low, p. ong, and k. c. cheah, “solving the optimal path planning of a mobile robot using improved q-learning,” rob. auton. syst., vol. 115, pp. 143–161, 2019. [14] d. karaboga and b. gorkemli, “solving traveling salesman problem by using combinatorial artificial bee colony algorithms,” int. j. artif. intell. tools, vol. 28, no. 01, p. 1950004, 2019. [15] e. a. hadi and s. by, “multi-objective decision maker for single and multi-robot path planning.” m. sc. thesis, control and system dept., university of technology, zahraa a. abdullah al-khwarizmi engineering journal, vol. 21, no.2, pp. 42-52 (2025) 51 baghdad-iraq, 2018. [16] b. m. abed and w. m. jasim, “hybrid approach for multi-objective optimization path planning with moving target,” indones. j. electr. eng. comput. sci., vol. 29, no. 1, pp. 348–357, 2023. [17] d. karaboga, “an idea based on honey bee swarm for numerical optimization,” 2005. [18] n. h. abbas and f. m. ali, “path planning of an autonomous mobile robot using directed artificial bee colony algorithm,” int. j. comput. appl., vol. 96, no. 11, pp. 11–16, 2014. [19] d. karaboga and b. akay, “a comparative study of artificial bee colony algorithm,” appl. math. comput., vol. 214, no. 1, pp. 108–132, 2009. [20] l. sun, b. feng, t. chen, d. zhao, and y. xin, “equalized grey wolf optimizer with refraction opposite learning,” comput. intell. neurosci., vol. 2022, 2022. [21] j. li and f. yang, “task assignment strategy for multi-robot based on improved grey wolf optimizer,” j. ambient intell. humaniz. comput., vol. 11, no. 12, pp. 6319–6335, 2020. ( 2025) 42-52، صفحة 2، العدد21مجلة الخوارزمي الهندسية المجلدزهراء عبد 52 تخطيط المسار المستقل وتجنب العوائق للروبوت المتحرك ذو العجالت باستخدام تحسين الذئب الرمادي 2نبيل حسن هادي، *1زهراء عبد 1 ، بغداد، العراق بغداد جامعة، كليةالهندسة ، الميكانيكية الهندسة قسم ، بغداد، العراق بغداد جامعة، كليةالهندسة، الطيران هندسة قسم 2 zahraa.abdullah2003d@coeng.uobaghdad.edu.iq البريد االلكتروني: * المستخلص تنفيذ ومقارنة تجنب العوائق لروبوت متحرك ذاتي الحركة (gwo)باستخدام خوارزمية تحسين الذئب الرمادي ( (wmrهدفت هذه الدراسة إلى أجريت الدراسة من خالل ثالثة سيناريوهات، تم تصميم كل منها الختبار أداء الخوارزمية في ظل ظروف .(abc) وخوارزمية مستعمرة النحل االصطناعي لتحديد المسار األكثر كفاءة وأقصر وأكثر أمانًا لروبوت gwoمختلفة، مع مراعاة العوائق الدائرية الثابتة والمتحركة في البيئة المحيطة. تم استخدام خوارزمية wmr من نقطة البداية إلى موقع الهدف. أظهرت النتائج أن خوارزميةgwo تفوقت على خوارزميةabc مما مكن ،wmr من تجنب العوائق بشكل ٪ للسيناريوهات الثالثة على التوالي.1.97٪ و 2.2٪ و 1.42٪، وبمسافة أقصر بنسبة 4.6٪ و 2.8٪ و 11.8أسرع بنسبة mailto:zahraa.abdullah2003d@coeng.uobaghdad.edu.iq 2-5فورمة جديدة this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 20, no. 3, september, (2024), pp. 11_19 robust proportional integral-state feedback with disturbance observer for 2-dof helicopter system shatha abd al kareem mohammed*, ali hussien mary**, ali al‐abadi*** and mohammed ghufran khidhir abboosh**** *, **department of mechatronics engineering, al-khwarizmi college of engineering, university of baghdad, baghdad, iraq ***friedrich-alexander university, germany ****department of data science and visualization, university of debrecen, hungary *email: shatha.mohammed1602@kecbu.uobaghdad.edu.iq (corresponding author) **email: alimary76@kecbu.uobaghdad.edu.iq ***email: ali.al-abadi@fau.de ****email: abboosh.mohammed@inf.unideb.hu (received 10 january 2024; revised 26 march 2024; accepted 23 april 2024; published 1 september 2024) https://doi.org/10.22153/kej.2024.04.001 abstract this paper presents a new optimal robust control algorithm based on a proportional-integral (pi) and state feedback controller with a state disturbance observer for the two degrees-of-freedom helicopter system. a disturbance observer is used to improve the robustness of the proposed controller instead of using high gain to reject the external disturbance. combining the pi controller with the state feedback controller improved the performance of the controlled system. simulations based on matlab 2022 are performed to compare the proposed controller with the linear quadratic regulator controller and investigate the performance and robustness of the proposed control method. the comparison between controllers was made under three cases: 1) nominal model, 2) disturbance rejection and 3) system uncertainty. the proposed algorithm shows good performance, which was confirmed clearly by the simulation results that illustrate the transient specifications represented by no overshot, the smallest settling time, and the smallest integral square error. the algorithm also indicates a good choice of objective function based on the infinity norm of the transfer function to ensure high robustness regardless of the external disturbance and parameter variations in the system. keywords: helicopter system; robust control; pi controller. 1. introduction nowadays, helicopters are employed in different applications, including agriculture, civilian work and military. this expansion in helicopter applications has led researchers to develop different control methods to improve the performance of helicopter systems [1]. the challenge is that the helicopter system suffers from nonlinearity and high coupling between the pitch and yaw angles, in addition to its exposure to external disturbance and system uncertainties. a quanser two-degrees of freedom (dof) has been used to examine the control methods [2, 3]. lqr is widely used for creating the optimal controller for helicopter systems because of its efficiency and stability. in [4], adaptive control technology is provided with lqr, and the weighting matrices q and r are selected for the best performance. the author combined lqr with model reference control, depending on the inverse lyapunov function, enhancing the tracking performance by addressing external disturbances in the system [5]. a model reference adaptive control (mrac) method is used with the lqr controller to improve the robustness of the helicopter system to address mailto:shatha.mohammed1602@kecbu.uobaghdad.edu.iq mailto:alimary76@kecbu.uobaghdad.edu.iq https://doi.org/10.22153/kej.2024.04.001 shatha abd al kareem al-khwarizmi engineering journal, vol. 20, no.3, p.p. 1119(2024) 12 the issue of parameter variations [6]. sliding mode controls (smcs) have been successfully used to manage numerous linear and nonlinear systems [7]. in [8], the sliding mode with variable gainbased system states and tracking error without disturbance estimation was presented to control the orientation of the yaw angle. jiang et al. suggest using the integral sliding mode control to regulate the helicopter system, improve the trajectory tracking and attenuate the effect of the disturbance by choosing the appropriate sliding surface [9]. many methods have been suggested to improve smc to control the helicopter system, including smc with metaheuristics optimization algorithm [10], smc with adaptive control [11], smc with quantum logic [12], robust control with the same theory [13], super twisting smc with particle filter [14], and smc with fractional control and reinforcement learning [15]. however, chattering caused by a discontinuity in the control signal may be unsuccessful in the smc because it can damage the actuator of the controlled system [9]. for the last few years, intelligent computing techniques, such as neural networks, fuzzy systems and genetic algorithms, have been successfully used to solve control challenges of various complicated systems. neural networks and fuzzy logic have been effectively used to regulate various types of nonlinear systems [16, 17]. the fuzzy logic controller for the proposed controller’s parameters is developed using metaheuristic methods and adaptive control theory for a 3-dof helicopter system [18]. the genetic algorithm is enhanced to execute a fuzzy pid controller [19]. the best sliding mode controller variables to control a nonlinear helicopter model are adaptively determined using fuzzy logic [20]. the simplicity of a pid controller has motivated many researchers to use it in the control of different complex systems, and their performance improved by combining them with different control strategies [21]. in [22], mimo pid controllers are presented to achieve the performance of a linear quadratic regulator for a 2dof helicopter system with bounded uncertainties. raafat shalaby et al. propose a fractional pid controller for a 2-dof nonlinear helicopter system with the parameters of the proposed controller tuned by a machine learning algorithm and the stability analysis approved based lyapunov theorem [23]. although the previously proposed control methods have yielded good results, their implementation can pose some difficulties. thus, this paper presents a state feedback tracking controller with a pi controller by using a disturbance observer that considers the simplicity of pi and the efficiency and stability of the state feedback controller. the two-dof helicopter model and the linearization of the dynamic model are illustrated in the next section. section 3 describes the procedures for designing the proposed robust pi-sfb controller. section 4 presents the simulation results and discussion. the last part presents the conclusion. 2. two-dof helicopter model fig. 1 shows that the 2-dof helicopter model has two degrees of freedom represented by the pitch (ψ) and yaw (θ) angles. the yaw angle refers to motion around the z axis, while the pitch angle refers to rotation around the y axis. helicopter systems have two blades, each driven by a dc motor. the motor input voltages are the control signals that determine the system’s yaw and pitch angles to track the intended trajectory [24]. fig. 1. two-dof helicopter system [25]. the nonlinearity of the helicopter dynamic model can be expressed as follows [10]: (𝐽𝑝𝑝 + 𝑚𝑙2)θ̈ = 𝐾𝑝𝑝𝑉𝑝𝑝 + 𝐾𝑝y𝑉𝑦𝑦 − 𝐵𝑝𝑝�̇� + 𝜁(𝑡) …(1) (𝐽𝑦𝑦 + 𝑚𝑙2𝑐𝑜𝑠2(𝜃)) �̈� = 𝐾𝑦𝑝𝑉𝑝𝑝 + 𝐾𝑦y𝑉𝑦𝑦 − 𝐵𝑦𝑦�̇� + ℵ(𝑡) …(2) 𝜁(𝑡) = −𝑚𝑙2𝑠𝑖𝑛(𝜃) 𝑐𝑜𝑠(𝜃) �̇�2 − 𝑚𝑔𝑙𝑐𝑜𝑠(𝜃) … (3) ℵ(𝑡) = 2𝑚𝑙2�̇�𝑠𝑖𝑛(𝜃) 𝑐𝑜𝑠(𝜃) �̇� …(4) where �̇�(𝑡) and �̇�(𝑡) represent the pitch and yaw velocities, respectively. 𝐾𝑝𝑝, 𝐾𝑝y, 𝐾𝑦𝑝 and 𝐾𝑦y are the thrust torque constants, and 𝑉𝑝𝑝 and 𝑉𝑦𝑦 are the input voltages to dc motors. 𝐽𝑝𝑝, 𝐽𝑦𝑦, 𝐵𝑝𝑝 and 𝐵𝑦𝑦 denote the moment of inertia and viscous damping about pitch and yaw axes, respectively. 𝑚 shatha abd al kareem al-khwarizmi engineering journal, vol. 20, no.3, p.p. 1119(2024) 13 represents the mass of the system, 𝑙 is the length and 𝑔 is the gravitational acceleration. table 1 lists the nominal values of these parameters. table 1. parameters values. parameter 𝑽𝒂𝒍𝒖𝒆 𝐾𝑝𝑝 0.204nm/v 𝐾𝑝𝑦 0.006nm/v 𝐾𝑦𝑝 0.021nm/v 𝐾𝑦𝑦 0.072nm/v 𝐵𝑝𝑝 0.800n/v 𝐵𝑦𝑦 0.318n/v 𝐽𝑝𝑝 0.038kg.m2 𝐽𝑦𝑦 0.043kg.m2 𝑚 1.387kg 𝑙 0.186 m the linearized dynamic model of the helicopter system can be represented as follows: �̇�(𝑡) = 𝐴𝑥(𝑡) + 𝐵𝑢(𝑡) …(5) 𝑦(𝑡) = 𝐶𝑥(𝑡) …(6) x(t) = [θ(t) ψ(t) θ̇(t) ψ̇(t)]t …(7) where 𝑥 is the state variables, 𝑢 is the input and 𝑦 is the output control. 𝑢 = [𝑉𝑝𝑝 𝑉𝑦𝑦]𝑇 , 𝑦 = [𝜓(𝑡) 𝜃(𝑡)]𝑇 …(8) 𝐴 = [ 0 0 1 0 0 0 0 1 0 0 −(0.800n/v) 0.038kg.m2+1.387kg(0.186 m)2 0 0 0 0 −(0.318n/v) 0.043kg.m2+1.387kg(0.186 m)2] …(9) b = [ 0 0 0 0 0.204nm/v 0.038kg.m2+1.387kg(0.186 m)2 0.021nm/v 0.043kg.m2+1.387kg(0.186 m)2 0.006nm/v 0.038kg.m2+1.387kg(0.186 m)2 0.072nm/v 0.043kg.m2+1.387kg(0.186 m)2] …(10) 𝐶 = [ 1 0 0 0 0 1 0 0 ] ...(11) 3. proposed robust pi-sfb controller design this section presents the design procedures of the proposed controller that integrates pi with state feedback (sfb) controllers. the parameters of the proposed controller are obtained by using an optimization algorithm to obtain maximum robustness against external disturbance and system uncertainty. fig. 2 shows the block diagram of the proposed closed-loop system. section 3.1 discusses the state feedback design, while section 3.2 presents a new control law that combines sfb with pi to achieve good tracking with high robustness against system uncertainty and external disturbance. fig. 2. proposed robust control method. 3.1. state feedback with pi the proposed control law is composed of the state feedback term (𝑢𝑓𝑏) and pi term (𝑢𝑖) as expressed below: 𝑢 = 𝑢𝑃𝐼 + 𝑢𝑓𝑏 …(12) 𝑢𝑝𝑖 = −𝑘𝑝 ∫ 𝑒(𝑡)𝑑𝑡 𝑡𝑓 0 + 𝑘𝑖𝑒(𝑡) … (13) 𝑢𝑓𝑏 = −𝑘1 𝑥(𝑡) …(14) the state space of the pi controller can be written shatha abd al kareem al-khwarizmi engineering journal, vol. 20, no.3, p.p. 1119(2024) 14 as follows: �̇�𝑝𝑖 = 𝐴𝑃𝐼𝑥𝑃𝐼 + 𝐵𝑃𝐼(𝑟 − 𝐶𝑥) …(15) 𝑢𝑃𝐼 = 𝐶𝑃𝐼𝑥𝑃𝐼 + 𝐷𝑃𝐼(𝑟 − 𝐶𝑥) …(16) where 𝐴𝑃𝐼 = [ 0 1 0 0 ] , 𝐵𝑃𝐼 = [ 0 1 ] , 𝐶𝑃𝐼 = [𝑘𝑖 𝑘𝑝], 𝐷𝑃𝐼 = 𝑘𝑝 in practice, measuring the states of the system is not easy; thus, an observer is used for estimating the states. in this paper, the proportional integral observer will estimate the state and disturbance. 3.2. proportional integral disturbance – state observer the state space for the proportional integral observer (pio) is expressed as follows: �̇� = 0 …(17) �̇� = 𝐴𝑥 + 𝐵𝑢𝑓𝑏 + 𝐿𝑃(𝑦 − 𝐶𝑥) + 𝐸�̂� …(18) �̇̂� = 𝐿𝐼(𝑦 − 𝐶𝑥) …(19) where 𝐿𝑃 and 𝐿𝐼 denote the estimator gains for states and disturbance, respectively. 3.3. augmented sfb–pi control with pio the augmented state space for the proposed controller with the disturbance observer is expressed with a perturbation added to the system to discuss the robustness of the closed-loop feedback system. let 𝑢 = 𝑤 + 𝑢𝑃𝐼 + 𝑢𝑓𝑏2 − 𝐾1𝑥 …(20) then �̇� = 𝐴𝑥 + 𝐵(𝑢𝑃𝐼 − 𝐾1𝑥) + 𝐵𝑤 + 𝐸𝑑 …(21) �̇� = 𝐴𝑥 + 𝐵(𝐶𝑃𝐼𝑥𝑃𝐼 + 𝐷𝑃𝐼𝑟 − 𝐷𝑃𝐼𝐶𝑥) − 𝐵𝐾1𝑥 + 𝐵𝑤 + 𝐸𝑑 …(22) �̇� = 𝐴𝑥 − 𝐵𝐾1𝑥 + 𝐵(𝐶𝑃𝐼𝑥𝑃𝐼 + 𝐷𝑃𝐼𝑟 − 𝐷𝑃𝐼𝐶𝑥) + 𝐿𝑃𝐶(𝑥 − 𝑥) + 𝐸�̂� = (𝐿𝑃𝐶 − 𝐵𝐷𝑃𝐼𝐶)𝑥 + (𝐴 − 𝐵𝐾1 − 𝐿𝑃𝐶)𝑥 + 𝐵𝐶𝑃𝐼𝑥𝑃𝐼 − 𝐵𝐷𝑃𝐼𝑟 + 𝐸�̂� … (23) �̇̂� = 𝐿𝐼𝐶𝑥 − 𝐿𝐼𝐶𝑥 …(24) finally, the state space for the augmented system can be expressed as follows: [ �̇� �̇�𝑃𝐼 �̇� �̇̂� ] = [ 𝐴 − 𝐵𝐷𝑃𝐼𝐶 𝐵𝐶𝑃𝐼 −𝐵𝐾1 𝐸 − 𝐵𝑃𝐼𝐶 𝐴𝑃𝐼 0 0 𝐿𝑃𝐶 − 𝐵𝐷𝑃𝐼𝐶 𝐵𝐶𝑃𝐼 𝐴 − 𝐵𝐾1 − 𝐿𝑃𝐶 0 𝐿𝐼𝐶 0 −𝐿𝐼𝐶 0 ] [ 𝑥 𝑥𝑃𝐼 𝑥 𝑑 ] + [ 𝐵 0 0 0 ]𝑤 + [ 𝐵𝐷𝑃𝐼 𝐵𝑃𝐼 −𝐵𝐷𝑃𝐼 0 ] 𝑟 …(25) the controller and observer gains will be tuned to obtain the minimum infinity norm of the system from 𝑤(𝑡) to 𝑣(𝑡) which is reciprocally called robustness bound. a closed loop system is always stable if it satisfies the following condition regardless of the value of perturbation: ‖∇(𝑠)‖∞ < 𝛾 …(26) where ‖∇(𝑠)‖∞ ≝ sup𝜎(∇(𝑗𝑤)) …(27) 𝛾 is the reciprocal of the infinity norm of the system from 𝑤(𝑡) to 𝑣(𝑡). 𝛾 = 1 ‖g(𝑠)‖∞ …(28) g(𝑠) represents the transfer function from 𝑤(𝑡) to 𝑣(𝑡). observer gain will be determined by setting the cost function of the optimization algorithm equal to the robustness bound. 4. simulation results the matlab 2022 program was used to simulate the helicopter system with two dofs to investigate the effectiveness and performance of the proposed controller in terms of tracking and robustness. a comparison is made between the proposed controller and the standard lqr. the parameters of the proposed controller used in this simulation after using (fminsearch) function as an optimization algorithm are 𝐾1 = [ 40.5 131.7 5 7.4 −20.3 440 −7 24 ], 𝐾𝑝 = [ 46 100 ],𝐾𝑖 = [161 200 ], 𝐿𝑃 = [ 2.18 51.7 2.4 2.8 21.6 −11.2 100 29.1 ] , 𝐿𝐼 = [ 17.3 100.7 200.1 90.1 ] . while the parameters of standard lqr controller used are 𝐿𝑄𝑅 = [ 30.1 1.1 6.6 −0.2 −0.05 3.1 −1.5 5 ] . 4.1. step reference tracking shatha abd al kareem al-khwarizmi engineering journal, vol. 20, no.3, p.p. 1119(2024) 15 this case discusses the performance of the proposed controller and the lqr controllers when the input is the unit step with a nominal model, and the simulation results are shown in figures 3 and 4. the figures show that the proposed controller and lqr track the reference input successfully with approximately the same rise (𝑡𝑟) and settling times(𝑡𝑠) but no overshoot (𝑀𝑝) can be observed in the proposed controller with high overshoot with the lqr controller. tables 2 and 3 list the transient specifications for pitch and yaw models, respectively. the integral square errors (ises) for pitch and yaw models are shown in the tables. these performances clearly indicate that the proposed controller outperforms the lqr controllers. fig. 3. step response for pitch model. fig. 4. step response for yaw model. table 2, transient specifications for pitch model for nominal case. table 3, transient specifications for the yaw model for the nominal case. 4.2. disturbance rejection a constant disturbance with amplitude 1 has been injected at t =3 sec to illustrate the robustness of the proposed control method. the simulation results shown in figures 5 and 6 indicate the ability of the proposed controller to guide the trajectory of the system to the reference input, indicating robustness against external disturbance. these figures show the proposed controller quickly reached the reference signal and rejected the disturbance. the results indicate a high effect for disturbance in the case of lqr especially for the yaw model. figures 7 and 8 show the integral square error for the pitch and yaw models, respectively. the proposed controller has the smallest iae for both models, illustrating the superiority of the proposed controller. the results of this section indicate that the pi term, which is added to the state feedback controller, can reject the disturbance quickly, taking advantage of using a proportional integral observer that can estimate the state and disturbance correctly. method 𝑴𝒑 𝒕𝒓(sec) 𝒕𝒔(sec) iae proposed 0.6589 0.7683 1.1192 0.3821 lqr 4.7721 0.5479 1.4513 0.4165 method 𝑴𝒑 𝒕𝒓(sec) 𝒕𝒔(sec) iae proposed 0.0018 1.7572 2.4720 0.8251 lqr 7.5219 1.1112 2.0062 0.8981 shatha abd al kareem al-khwarizmi engineering journal, vol. 20, no.3, p.p. 1119(2024) 16 fig. 5. response pitch model for disturbance. fig. 6. response yaw model for disturbance. fig. 7. iae variations of pitch model. fig. 8. iae variations of yaw model. 4.3. system uncertainty the parameters of the system have been changed to 20% of their nominal values to investigate the robustness of the proposed control method against the parameter variations. the simulation results, as shown in figures 9 and 10, indicate the high robustness of the proposed controller against system uncertainties. the transient specifications, which are listed in tables 4 and 5, illustrate the superiority of the proposed controller and show that the proposed controller’s performance is not affected by system uncertainty. moreover, the ise show the high efficiency of the proposed controller in the presence of the parameter variations. the results of this section indicate a good choice of the objective function, which is based on the infinity norm of the transfer function to ensure good performance regardless of the variations in the parameters of the system. fig. 9. response pitch model for uncertainty. fig. 10. response yaw model for uncertainty. shatha abd al kareem al-khwarizmi engineering journal, vol. 20, no.3, p.p. 1119(2024) 17 table 4, transient specifications for pitch model for uncertainty case. table 5, transient specifications for yaw model for uncertainty case. 5. conclusion this paper proposes a new robust and simple control method based pi and state feedback controllers with state and disturbance observers for a 2-dof helicopter system. the system norm is used as a cost function to tune the parameters of the proposed controller and ensure the robustness of the proposed control method against external disturbance and system uncertainty. three cases were used to examine the efficiency and robustness of the proposed controller. simulation results show the high ability of the proposed method to reject the external disturbance and good performance in the presence of system uncertainty. 6. references [1] h. liu, “trajectory tracking control for a quadrotor helicopter in the presence of cyber-attacks,” isa trans., vol. 143, pp. 1–9, dec. 2023. [2] b. wang, x. yu, l. mu, and y. zhang, “disturbance observer-based adaptive faulttolerant control for a quadrotor helicopter subject to parametric uncertainties and external disturbances,” mech. syst. signal process., vol. 120, pp. 727–743, apr. 2019. [3] h. mary, a. h. miry, and m. h. miry, “design robust h ∞ -pid controller for a helicopter system using sequential quadratic programming algorithm,” j. chinese inst. eng., vol. 45, no. 8, pp. 688–696, nov. 2022. [4] p. nuthi and k. subbarao, “experimental verification of linear and adaptive control techniques for a two degrees-of-freedom helicopter,” j. dyn. syst. meas. control, vol. 137, no. 6, jun. 2015. [5] r. ganapathy subramanian and v. k. elumalai, “robust mrac augmented baseline lqr for tracking control of 2 dof helicopter,” rob. auton. syst., vol. 86, pp. 70–77, dec. 2016. [6] s. karthick, s. kanthalakshmi, e. vinodh kumar, v. joshi kumar, and a. ezhil kumaran, “experimental validation of adaptive augmented lqi control for a 2 dof helicopter,” iete j. res., pp. 1–13, nov. 2022. [7] t. kara and a. h. mary, “adaptive pdsmc for nonlinear robotic manipulator tracking control,” stud. informatics control, vol. 26, no. 1, mar. 2017. [8] k. r. palepogu and s. mahapatra, “design of sliding mode control with state varying gains for a benchmark twin rotor mimo system in horizontal motion,” eur. j. control, p. 100909, oct. 2023. [9] t. jiang, d. lin, and t. song, “novel integral sliding mode control for small-scale unmanned helicopters,” j. franklin inst., vol. 356, no. 5, pp. 2668–2689, mar. 2019. [10] w. boukadida, a. benamor, h. messaoud, and p. siarry, “multi-objective design of optimal higher order sliding mode control for robust tracking of 2-dof helicopter system based on metaheuristics,” aerosp. sci. technol., vol. 91, pp. 442–455, aug. 2019. [11] s. m. schlanbusch and j. zhou, “adaptive predictor-based control for a helicopter system with input delays: design and experiments,” j. autom. intell., feb. 2024. [12] f. chen, r. jiang, c. wen, and r. su, “selfrepairing control of a helicopter with input time delay via adaptive global sliding mode control and quantum logic,” inf. sci. (ny)., vol. 316, pp. 123–131, sep. 2015. method 𝑴𝒑 𝒕𝒓(sec) 𝒕𝒔(sec) iae proposed 0.7765 0.7224 1.1940 0.3812 lqr 8.1564 0.5406 2.2564 0.4538 method 𝑴𝒑 𝒕𝒓(sec) 𝒕𝒔(sec) iae proposed 0.0028 1.7858 2.5102 0.8252 lqr 28.5498 1.0329 4.3388 1.1384 shatha abd al kareem al-khwarizmi engineering journal, vol. 20, no.3, p.p. 1119(2024) 18 [13] y. zhu and h. zhao, “robust control design for electric helicopter tail deceleration system: fuzzy view and stackelberg game theory-based optimization,” isa trans., vol. 145, pp. 51–62, feb. 2024. [14] m. raghappriya and s. kanthalakshmi, “particle filter-based adaptive super-twisting sliding mode fault-tolerant control for helicopter systems,” int. j. dyn. control, nov. 2023. [15] t. a. mahmoud, m. el-hossainy, b. abozalam, and r. shalaby, “fractional-order fuzzy sliding mode control of uncertain nonlinear mimo systems using fractionalorder reinforcement learning,” complex intell. syst., jan. 2024. [16] a. h. mary, t. kara, and a. h. miry, “inverse kinematics solution for robotic manipulators based on fuzzy logic and pd control,” in 2016 al-sadeq international conference on multidisciplinary in it and communication science and applications (aic-mitcsa), may 2016, pp. 1–6. [17] m. m. a. al-isawi, a. j. attiya, and j. o. adoghe, “uav control based on dual lqr and fuzzy-pid controller,” alkhwarizmi eng. j., vol. 16, no. 3, pp. 43–53, sep. 2020. [18] s. naderi, m. j. blondin, and b. rezaie, “optimizing an adaptive fuzzy logic controller of a 3-dof helicopter with a modified pso algorithm,” int. j. dyn. control, vol. 11, no. 4, pp. 1895–1913, aug. 2023. [19] y. hu, y. yang, s. li, and y. zhou, “fuzzy controller design of micro-unmanned helicopter relying on improved genetic optimization algorithm,” aerosp. sci. technol., vol. 98, p. 105685, mar. 2020. [20] f. pakro and a. a. nikkhah, “a fuzzy adaptive controller design for integrated guidance and control of a nonlinear model helicopter,” int. j. dyn. control, vol. 11, no. 2, pp. 701–716, apr. 2023. [21] m. s. ahmed, a. h. m. mary, and h. h. jasim, “robust computed torque control for uncertain robotic manipulators,” alkhwarizmi eng. j., vol. 17, no. 3, pp. 22–28, sep. 2021. [22] f. gopmandal and a. ghosh, “lqr-based mimo pid control of a 2-dof helicopter system with uncertain cross-coupled gain,” ifac-papersonline, vol. 55, no. 22, pp. 183–188, 2022. [23] r. shalaby, m. el-hossainy, b. abo-zalam, and t. a. mahmoud, “optimal fractionalorder pid controller based on fractionalorder actor-critic algorithm,” neural comput. appl., vol. 35, no. 3, pp. 2347– 2380, jan. 2023. [24] s. s. butt, h. sun, and h. aschemann, “comparison of backstepping-based sliding mode and adaptive backstepping for a robust control of a twin rotor helicopter,” 2016, pp. 3–30. [25] l. a. ramírez, m. a. zuñiga, g. romero, e. alcorta-garcía, and a. j. muñoz-vázquez, “fault diagnosis for a class of robotic systems with application to 2-dof helicopter,” appl. sci., vol. 10, no. 23, p. 8359, nov. 2020. (2024) 11-19، صفحة 3، العدد20مجلة الخوارزمي الهندسية المجلد شذى عبد الكريم محمد 19 رات رد الفعل الراجع مع مراقب االضطراب لنظام طائ و piمتحكم التكامل النسبي المتين هليكوبتر تتحرك بدرجتين من الحرية ****محمد غفران خضر عبوش ،***علي العبادي، **علي حسين مري ، *شذى عبد الكريم محمد العراق بغداد،،جامعة بغداد ،كلية الهندسة الخوارزمي ،** قسم هندسة الميكاترونكس ،* ألمانيا ،نجامعة فريدريش ألكسندر*** المجر ،قسم علوم البيانات والتصور، جامعة ديبريسين**** shatha.mohammed1602@kecbu.uobaghdad.edu.iqالبريد االلكتروني : * kecbu.uobaghdad.edu.iq76alimary@**البريد االلكتروني : abadi@fau.de-ali.al *البريد االلكتروني :** abboosh.mohammed@inf.unideb.huااللكتروني : البريد **** المستخلص مراقب مع (sfb) لراجعووحدة التحكم في رد الفعل ا (piالتكامل النسبي ) متحكم على قائمة تحكم جديدة مثالية ومتينة تقدم هذه الورقة خوارزمية م ال من استخداقترحة، بدالمتم استخدام مراقب االضطراب لتحسين متانة وحدة التحكم تتحرك بدرجتين من الحرية. هليكوبتراضطراب الحالة لنظام طائرات لتحكم في ردود الفعل ووحدة ا piفي حين تم تحسين أداء النظام المتحكم به من خالل الجمع بين وحدة التحكم الكسب العالي لرفض االضطراب الخارجي. ل التحقق من أداء ومتانة , من أجlqrتحكم اللمقارنة وحدة التحكم المقترحة مع وحدة matlab 2022تم اجراء عمليات محاكاة تعتمد على الخاصة بالحالة. تظهر الخوارزمية ظام. ( عدم يقين الن3( رفض االضطراب 2( النموذج االسمي 1تمت المقارنة بين المتحكمات في ثالث حاالت: . المقترحةطريقة التحكم ار، رصغر زمن استقاوز، وأالمقترحة أداء جيد، والذي يمكن تأكيده بوضوح من خالل نتائج المحاكاة التي توضح المواصفات العابرة المتمثلة في عدم التج ضمان متانة ل ة الرياضيةاهية للدالالقاعدة الالمتنبناًء على الجيد لدالة الهدفختيار االوأصغر خطأ مربع متكامل. عالوة على ذلك، تشير هذه الخوارزمية إلى عالية بغض النظر عن االضطرابات الخارجية وتغيرات المعلمات في النظام.  mailto:alimary76@kecbu.uobaghdad.edu.iq abstract 1. introduction 2. two-dof helicopter model 3. proposed robust pi-sfb controller design 3.1. state feedback with pi 3.2. proportional integral disturbance –state observer 3.3. augmented sfb–pi control with pio 4. simulation results 4.1. step reference tracking 4.2. disturbance rejection 4.3. system uncertainty 5. conclusion 6. references this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 20, no. 1, march, (2024), p p. 7688 learn of machine learning to predict consumed -applying scikit khwarizmi college of engineering, baghdad, iraq-energy in al reem omar mahdi* wisam s. hacham** *,**department of mechatronics engineering / al-khwarizmi college of engineering / university of baghdad/ iraq omarreem07@gmail.com :lmaie * corresponding author: **email: wisam@kecbu.uobaghdad.edu.iq (received 20 july 2023; accepted 2 october 2023; published 1 march 2024) https://doi.org/10.22153/kej.2024.10.005 abstract buildings account for 40% of energy usage worldwide. the physical characteristics of the building, the effectiveness of the heating and cooling systems, the inhabitants' activities, and the sustainability of the building are just a few of the many factors that influence a building's energy consumption. it is quite challenging to estimate the energy requirements of a structure. estimating the building's energy demand is vital to increase sustainability and develop sustainable energy sources to lower carbon dioxide emissions from the burning of fossil fuels. the energy used in the lecture hall at the university of baghdad (uob), located in baghdad, iraq's al-khwarizmi college of engineering, is explained in this study. the weather data and the building construction information were collected for a specific period and put into a specific data set. that data was used to find the value of energy consumption in the building using artificial intelligence and data analysis. a python library called scikit-learn is used to implement machine learning algorithms. in particular, the multi-layer perceptron regressor (mlpregressor) algorithm was used to predict the consumption. the importance of this work lies in predicting the amount of energy consumed. the outcomes of this work can be used to predict the energy consumed by any building before it is built. the used methodology shows the ability to predict energy performance in educational buildings using previous results and train the model on them, and prediction accuracy depends on the amount of data available for the training in artificial intelligence (ai) steps to give the highest accuracy. the prediction was checked using root-mean-square error (rmse) and coefficient of determination (r²) and we arrived at 0.16 and 0.97 for rmse and r², respectively. keywords: prediction, energy consumption, regression algorithm, scikit-learn algorithm. 1. introduction as the world's population grows, so does the amount of energy used in buildings. numerous physical and sociological elements have an impact on it. the need for basic services like water, gas, and power has increased exponentially due to increasing consumer culture and urbanization activities; this demand is predicted to double by 2050 when compared to 2010[1]. building-related activities account for more than 30% of world energy demand and a quarter of greenhouse gas emissions [2-4]. for instance, the building industry accounts for 36% of co2 emissions and 40% of energy consumption in europe [5]. in contrast, the construction sector is responsible for 38.9% of the total primary energy requirement (per) in the united states [6]. building stocks in china accounted for around 24.1% of the total public energy usage in 1996 and 27.5% in 2011. building stocks are predicted to reach roughly 35% by 2020 [7]. besides, in a cutting-edge city like hong kong, electricity generation accounts for 60% of the byproducts of fossil fuels, while buildings account for 89% of total power consumption[8]. mailto:wisam@kecbu.uobaghdad.edu.iq https://doi.org/10.22153/kej.2024.10.005 )2023(88 -67, p.p. 4khwarizmi engineering journal, vol. 19, no. -al reem omar mahdi 77 additionally, certain climate conditions around the world forced homes to use more energy for their heating, cooling, cooking, and refrigeration requirements. university buildings and commercial buildings, particularly offices, are thought to have high energy usage [9,10]. as a result, cutting back on energy use to achieve energy sustainability is recognized as a crucial strategy for lowering rising energy demand and emissions as well as tackling the problems associated with a warming globe because of the ongoing global rise in energy prices, so technological solutions are essential for reducing energy demand [11]. it is critical to examine the energy consumption patterns of buildings to establish energy efficiency measures that will assist us in achieving sustainability goals and net-zero greenhouse gas emission targets. the efficiency of energyconsuming equipment and appliances has improved with technological advancement. building energy usage has been decreased by retrofitting outdated air conditioning and cooling systems, switching to new lighting technology, and changing operating habits through energy efficiency projects [12]. here, an accurate prediction of energy used and its amount in the building will be performed to work on it to reach energy savings and different conservation measures. it will also help us select the best design for the building to reduce energy consumption. there are two ways to predict how much energy a structure will require. the first one is based on a physical model, whereas the other is data-driven. the physical modeling technique is also known as the "forward modeling approach." the physical modeling technique involves precise information about the structure, mechanical systems, and inhabitants' activities that may not be readily available to produce a mathematical model to predict the building's energy usage. to simulate and predict the energy consumption of buildings, the forward modeling technique frequently makes use of commercial software, such as doe-2, design builder, etc., as inputs. there are frequently only small differences in the outcomes across various software when the input values for the variables are the same or identical [13]. meanwhile, the physical model could not account for the sociocultural elements that might have an impact on how much energy residents use. the data-driven technique circumvents the constraints of using physical models to anticipate consumed energy by using data analysis using well-known data sets. typically, building sample simulations or collecting data is used to develop an energy-use database. artificial neural networks (ann), classification and regression trees (cart), multiple linear regression (mlr), and other data-driven methods are examples. other data-driven strategies have also been looked into by researchers. for instance, li et al. [14] built a hybrid teaching-learning artificial neural network model utilizing weather data, calendar data, occupancy patterns, and historical energy use data to anticipate the hourly electrical energy consumption for two educational facilities located in the usa and china. according to previous publications, relatively few studies have attempted to predict the annual consumption of energy for residential buildings using data from actual energy usage. based on the outcomes of simulations using commercial software, several studies have concentrated on monthly [15], daily [16-18], or hourly [16-20] energy use their benefit appears to be finding the best solution to reduce energy consumption. additionally, in the prediction model, the impacts of occupant behaviors on energy use are typically disregarded, and the bulk of the variables focus on meteorological data [16-19, and 21] or design variables of the building's façade [15 and 21-24]. as a result of this, estimates of homes' energy use vary, and socioeconomic and demographic information is frequently left out. due to the vast potential of artificial intelligence (ai), it is highly likely to play a significant role in advancing the study of energy conservation in buildings. consequently, numerous individuals passionate about the energy sector are compelled to explore the application of this technology. artificial intelligence (ai) is the study of developing intelligent machines capable of mimicking human cognition and doing tasks that would typically need human intelligence. machine learning, natural language processing, computer vision, robotics, and expert systems are other subfields of artificial intelligence. a subset of (ai) artificial intelligence comprises algorithms aimed to learn from data and progressively improve performance without the need for programming skills is called "machine learning". deep learning is a subfield of machine learning and artificial intelligence that entails training artificial neural networks with numerous layers to detect complicated patterns and representations in data. these networks are modeled after the form and functions of neural networks in the human brain. deep learning techniques are particularly wellsuited for big data processing because they can manage massive amounts of data while accurately detecting subtle patterns [25]. )2023(88 -67, p.p. 4khwarizmi engineering journal, vol. 19, no. -al reem omar mahdi 78 a subset of artificial intelligence (ai) involves teaching computers to analyze data make predictions and form conclusions without the need, for programming which it called machine learning (ml). in simpler terms, machine learning algorithms learn on their own by using data or experience, without needing any explicit instructions. the process of machine learning involves creating mathematical models and algorithms that can identify patterns, connections, and insights in datasets. these models are trained on labeled or unlabeled data to identify patterns and predict or respond to new, unexpected data. there are various types of machine learning methodologies, including supervised, unsupervised, and reinforcement learning[26]. the input data and appropriate target labels are coupled to train the supervised learning algorithm. as opposed to supervised learning, which uses labels to guide learning, unsupervised learning uses data that has not yet been labeled. where the trialand-error method used in reinforcement learning is used to train an algorithm. the approach obtains new knowledge by interacting with the environment and receiving positive or negative feedback. it aims to maximize advantages by behaving correctly in different situations . ml libraries are software packages that provide numerous tools, features, and techniques for developing and executing machine learning models. these libraries simplify and accelerate the process of developing machine learning applications. they generally include preimplemented algorithms, feature engineering, data pretreatment methods, metrics for model evaluation, and visualization tools. ml libraries that are widely used include tensorflow [28], pytorch [29], keras [30], scikit-learn [27], and many more. scikit-learn, a popular python package, provides a variety of tools for machine learning applications, including regression, clustering, classification, dimensionality reduction, and model selection. the tensorflow library, developed by google, is open-source and focused on numerical computation and deep learning. it offers a flexible framework for building and implementing machine learning models on many platforms. pytorch is another popular open-source library that's mostly used for deep learning. because pytorch has an intuitive interface and dynamic computational graphs, it is suitable for both research and production applications. theano or tensorflow is the foundation upon which the keras high-level neural network library is constructed. it provides an accessible api for creating and honing deep learning models . the goal of this work is to develop a forecast model for energy consumption based on data from the al-khwarizmi engineering college building at the university of baghdad (uob), in iraq. information was obtained on the building's architectural attributes, the social and demographic makeup of its tenants, and the quantity of energy consumed. the energy prediction model was enhanced using a multiple linear regression (mlr) technique to estimate power use. to find the model that generated the best predictions with the fewest inputs, we experimented with different training/validation ratios and counts of input variables. predicting the energy requirements of academic buildings can be aided by the study's conclusions. 2. multi-campus university setting the facilities of the uob are dispersed over its several campuses, which are located throughout the baghdad governorate of iraq in a variety of geographically dispersed places. the main campus, which occupies 325 hectares, is situated near al-jadriya. al-waziriyah, abu ghraib, bab al-mu'azzam, al-nahda, and al-adhamiya are the locations of other universities. all colleges are located in the province of baghdad, which enjoys a climate that is hot and dry in summer and cold and rainy in winter, and has all seasons: summer from june to august, fall from september to november, winter from december to february, and spring from march to may. al-jadriya campus is located in the heart of the iraqi capital, baghdad, on the rusafa side of the al-jadriya complex, and is surrounded by the tigris river from three directions, meaning that it is located on a peninsula, the capital of baghdad. the minimum, maximum, and mean temperatures in baghdad across all months of the year are shown in table (1) [31]. electricity also operates all facilities. some college campuses have a central heating and cooling system that relies on electricity. this campus contains a mixture of old and new buildings, where many retrofit projects have been undertaken. it also contains 13x absorption coolers. absorption coolers are thermally driven refrigeration systems that use a heat source, such as natural gas, propane, or solar energy, to generate cooling. the "13x" in the term refers to the )2023(88 -67, p.p. 4khwarizmi engineering journal, vol. 19, no. -al reem omar mahdi 79 coefficient of performance (cop) of the absorption cooler, indicating the ratio of cooling output to heat input. these coolers are commonly used in applications where electricity availability is limited or costly, or where alternative fuel sources are preferred. table 1, the average minimum, maximum, and mean temperature in baghdad the uob has 24 colleges, 3 high study institutes, and 9 centers spread across four main campuses. in this paper, the energy consumption in al-khwarizmi college of engineering (figure 1), which is located at the al-jadriya campus, will be discussed, and artificial intelligence (ai) will be applied to predict the amount of energy consumption. to use it to impose mechanisms to retrofit the building to reduce the energy consumed in these buildings and arrive at buildings with less energy consumption and zero carbon emissions in the future. khwarizmi college -1. lecturing building of al fig . .of engineering 3. the dataset characteristics the following subsections will illustrate building types, weather information, and education calendars to demonstrate whole the characteristics of the dataset incorporated in the used methodology. table (2) illustrates all these characteristics briefly. types of buildings 3.1 all campuses have varied applications for the buildings, which also result in different energy consumption patterns and operational schedules. the buildings are divided into the following seven groups based on their main uses. to be used for different modeling and analytical purposes, these categories are given as metadata.  instructional facilities: these include all structures utilized for basic and applied research as well as  lectures, workshops, tutorials, labs, and other instructional activities;  library buildings: structures that house libraries as well as expansive computer laboratories and quiet study areas for students;  administrative buildings: structures that are only utilized for university administration, including the hr, it, and finance departments. these are only utilized from 8 a.m. to 3 p.m. during working hours;  residential buildings: structures that house students;  mixed-use buildings: some structures combine administrative, research, and instructional activities; they include lecture halls, offices, and study areas;  sports facilities: these structures are utilized for sporting and leisure activities; and  other structures: these include facilities that do not fit into any of the categories mentioned above, such as greenhouses and animal kennels that are open round-the-clock. the college of engineering khwarizmi is classified as a mixed-use building, as the building contains classrooms, laboratories, and some administrative rooms. it also contains a library for the college. average temp.(°c) month jan. feb. march april may june july aug. sept. oct. nov. dec. year minimum 5 7 11.1 15.8 21.5 25.4 28 17 23.4 17.7 10.7 6.4 16.6 maximum 16.8 19.6 24.6 30.7 37 42.2 45.2 47 41.3 33.7 24.1 18.2 31.6 mean 10.9 13.3 17.8 23.3 29.3 33.8 36.6 36 32.3 25.7 17.4 12.3 24.1 )2023(88 -67, p.p. 4khwarizmi engineering journal, vol. 19, no. -al reem omar mahdi 80 weather information 3.2 weather information is crucial for correctly forecasting consumption patterns since it has a substantial correlation to utility usage [32] [33]. we can see from the dataset that the uob network uses more energy during the summer than it does during the winter. we must utilize the havc system and air conditioning in some sections of the building since the summer weather is too hot and dry. therefore, gathering weather data is important information for any dataset connected to energy. the iraqi meteorological network offers weather information to the general population. several important factors are included in the weather recordings from the weather network. in this dataset, we have retrieved dew point, apparent temperature, relative humidity, air temperature, wind speed, and wind direction. education calendar 3.3 working days and weekends are only depicted on the university's academic calendar during the summer. we programmatically encode all of this data into a code. the largest energy use time is said to be at the beginning of the semester and at the beginning of summer. the institution uses power to provide cooling for the buildings and student housing since a high number of students are required to attend during this time. applications involving energy forecasting would benefit from this knowledge. table 2, the dataset characteristics. 4. data discourse an existing data set located in kaggle was used, which contains a huge amount of information that i need it is unicon dataset, harsha moraliyage, et al. [39]. this reference describes all data and information contained in the data set, it contains a detailed description of the characteristics of the data collected. after that, i used this dataset to train the model to get high-efficiency results. then, my dataset was created according to my needs, which contains all the information to use in the test to achieve the specific goal, which is to measure the amount of energy consumed in the building. comma-separated values (csv) files are used to hold the energy data that has been gathered from every electrical board and building meta. a full explanation of the properties of the data obtained is provided in table 3. below is an explanation of the csv file used: • test.csv this file includes metadata of all we need, such as floor space, energy consumption title discretion buildings types 1) instructional facilities: 2) library buildings: 3) administrative buildings: 4) residential buildings: 5) mixed-use buildings: 6) sports facilities: other structures) 7 1) include lectures, workshops, tutorials, labs, and other instructional activities; 2) include libraries as well as expansive computer laboratories and quiet study areas for students; 3) including the hr, it, and finance departments. 4) including the house of the students; 5) combine administrative, research, and instructional activities; they include lecture halls, offices, and study areas; 6) including sporting and leisure activities; include facilities that do not fit into any of the categories ) 7 .mentioned above weather information baghdad weather information the iraqi meteorological network offers weather information to the general population. several important factors are included in the weather recordings from the weather network such as dew point, apparent temperature, relative humidity, air temperature, wind speed, and wind direction education calendar working time the targeted building's working hours are from 8 a.m. to 3 p.m., with peak occupancy typically observed between 9 a.m. and 1:30 p.m. our study focuses on the summer months of 2021 (march, april, may, and june), characterized by high occupancy and increased energy consumption. )2023(88 -67, p.p. 4khwarizmi engineering journal, vol. 19, no. -al reem omar mahdi 81 information for national meter identifiers (nmis), and weather data which contains weather information gathered from each of the weather stations. table 3 a summary of the used dataset. 5. methodology the unicon dataset will be used as applied by [39] to train the function because it contains a huge number of data points that give a good training result when our dataset is used to predict. after that, we start preprocessing. preprocessing refers to the set of techniques and steps used to prepare and transform raw data into a format suitable for further analysis and modeling. the main objectives of preprocessing are to clean, transform, and standardize the data to improve the quality and reliability of the subsequent analysis. preprocessing techniques may vary depending on the specific characteristics of the data and the requirements of the analysis or modeling task. in this work, the data was split into two parts, with 80 % training and 20 % testing the data. the area of the building and the weather changes in iraq affect the energy consumption of the targeted building. after that, the feature scaling technique will be used in data preprocessing by standardizing the numerical features of a dataset. it ensures that all features have a similar scale or range, which can improve the performance and stability of machine learning algorithms. the standardization scaling method transforms the features to have a zero mean and unit variance. it subtracts the mean value of each feature and divides it by the standard deviation. standardization preserves the shape of the distribution and is less affected by outliers. the selection of the feature scaling technique depends on the specific characteristics of the dataset and the requirements of the machine learning algorithm. the standardization method was used to scale the input values and get a specific scalar which is saved to use later when we enter our data set. figure 2 illustrates the workflow briefly. the energy consumption in the lecture building of the al-khwarizmi engineering college will be predicted using the scikit-learn library, which contains supervised machine learning [34]. regression models will be chosen because this study deals with prediction. the neural network model in sklearn will be used. in scikit-learn, the neural network models for supervised learning tasks are implemented through the `mlpregressor` class, which stands for multilayer perceptron. these models are based on artificial neural networks and will be used for solving regression problems. in this work, the `mlpregressor` class will be used for regression tasks, where the goal is to predict a continuous numerical value based on input features. multiple linear regression (mlr) will be employed in the prediction of building energy consumption as used by [35] and may be applied early in the design process to enhance building performance. in scikit-learn, neural network models are composed of several layers of sequentially arranged, networked nodes known as neurons. after receiving input signals, each neuron produces an output by applying an activation function and then sends the result to the layer below. hidden layers, which lie between the input and output layers, aid in the discovery of intricate linkages and patterns in the data. after you've established the model, you can train it using the 'fit' method by feeding it the goal values for the input data. during the training phase, the model updates its weights and biases to decrease the gap between predicted and actual output values. gradient descent and backpropagation are two typical techniques for this class data field description unit data output test.csv id unique identifier energy consumption.csv campus_id identification for the foreign key referencing the campus id room_area building's room space m2 apparent_temperature temperature of the specified location c° relative_humidity relative humidity air_temperature the outside weather temperature c° wind_speed wind speed m/s wind_direction wind direction angle ° dew_point_temperature dew point temperature c° hour hour of day for determining consumption hr )2023(88 -67, p.p. 4khwarizmi engineering journal, vol. 19, no. -al reem omar mahdi 81 optimization process. after training the model, use the 'predict' technique to make predictions on fresh, previously unknown data. after propagating the input data through its layers, the neural network model produces the predicted results. this might be beneficial for a variety of purposes, including estimating power use, saving electricity and energy, identifying appliances, projecting costs, and other energyrelated operations [36-38]. all of the model's parameters will be displayed in table 3. fig. 2. flowchart of key workflow. metrics are numerical measurements used in machine learning and data analysis to evaluate the quality or effectiveness of a model or algorithm. they provide unbiased benchmarks, such as mean_squared_error and r2_score, for assessing a model's performance on a given task or dataset [40]. r-squared determines the proportion of the dependent variable's variance that can be explained by the independent variables in the model. the scale ranges from 0 to 1, with higher values indicating a better match. in other words, rsquared reflects the adequacy of a regression model in explaining the variance and predicting the building's energy use. to predict energy consumption, we use our dataset to generate anticipated energy values using a trained algorithm to achieve high efficiency. by using weight values we can predict energy usage accurately and make well-informed choices regarding our energy consumption. .table 3 .list of parameters used in the algorithm name of parameter used parameter hidden_layer_sizes 60,170,150,80,80,160 solver sgd learning_rate adaptive activation function relu alpha value 0.0001 results. 6 the system was taught using the unicon dataset. it displayed predictive performance. through the utilization of a network framework, the experimental data-driven technique demonstrated that the neural network (nn) model exhibited precision, in forecasting energy usage. with a root mean square error (rmse) of 0.16 and an impressive r2 score of 0.97, the educated model delivers results. the r2 score shows how well the model captures patterns and trends accurately. it suggests that the model can explain 97% of the variations, in energy consumption data. furthermore, figure 3 illustrates the model's precision with a small root mean square error (rmse) of 0.16 indicating that the typical gap, between predicted and actual energy consumption figures is minimal. )2023(88 -67, p.p. 4khwarizmi engineering journal, vol. 19, no. -al reem omar mahdi 83 (proportion of score value -3. validation chart which shows rmse value (root mean square error) and r2. fig )variance the system is highly reliable and ideal, for predicting the energy usage of the building as, per the evaluation criteria. its outstanding performance enables stakeholders and decision-makers to accurately foresee and gauge energy consumption levels. with these foresight skills, they can make choices regarding how resources are allocated, manage energy, and optimize efficiency leading to improved energy efficiency and cost reductions, at the facility, in question. assessing the precision of a model a chart illustrating prediction errors could come in handy. the model generates projected values that are then contrasted with the outcomes in the dataset. in figure 4 you can see a representation of the differences, between the predicted and observed values. the prediction error plot serves as a tool to identify heteroscedasticity or noise, in data. noise refers to fluctuations or inconsistencies in data while heteroscedasticity indicates the varying levels of variability in the target variable, across ranges. by comparing expected and actual data discrepancies one can easily spot patterns and trends. fig.4. prediction error plot between actual and predicted values. a plot showing prediction errors is a tool, for assessing how much variability exists in a model. when the points on the plot are scattered randomly around zero it suggests that the model accurately captures the underlying patterns with deviation. on the other hand, if there are patterns or significant deviations, from zero it suggests that either the model did not consider all aspects of the data or that the predictions were highly unpredictable. studying the error map predictions gives us insights, into how our model is performing and helps identify areas where we can make enhancements. by conducting this analysis we can refine the model explore strategies and deepen our comprehension of the precision and reliability of our forecasts. the graph displaying prediction errors illustrates the variance, between estimated values 0.000 0.200 0.400 0.600 0.800 1.000 1.200 0 20 40 60 80 100 120 validation chart r2 test r2 train rmse )2023(88 -67, p.p. 4khwarizmi engineering journal, vol. 19, no. -al reem omar mahdi 84 enabling us to assess the models' accuracy, variability, and inconsistency. this tool plays a role, in assessing, improving, and studying prediction models. by utilizing our data and a forecasting model we can obtain estimates of consumption for march, may, june, and july generating updated values, for, over 120 days. this process involved applying a customized weight and factor derived from our training dataset leading to capabilities. these forecasts offer perspectives that can be used to enhance energy efficiency in the building. this information allows us to implement various strategies and ideas to enhance energy efficiency and reduce overall consumption. by leveraging the power of data-driven predictions, we can make informed decisions and implement effective measures to achieve energy-saving goals and contribute to sustainable practices in the building. in the figure above, the amount of predicted energy consumption during working days was illustrated, such as on day 60, which falls on thursday, april 29, 2021, the amount of predicted energy is nearly 540 kw/h. the amount of energy consumption increased with the increase in days due to the dry and hot weather in iraq and the requirement to start turning on the central cooling system used in the targeted building. .5. energy prediction of targeted building for 120 days of working fig. discussion. 7 the scikit-learn library was chosen for this study due to its ease of use, especially when compared to other libraries such as keras that may require more powerful computers. given that the objective of our paper is to predict energy consumption, regression techniques were deemed suitable and thus selected for implementation. extensive research conducted on previous studies revealed that artificial neural networks consistently yielded the best results. we decided to use this model because it showed accuracy during training and was efficient. before training the data we removed duplicates and rows with values using a data cleaning method. we then standardized the data to ensure it was processed optimally. this approach aids in making the data consistent and addressing its fluctuations and diverse value range. the dataset, for training was divided into two parts; testing and training and validation metrics, like root mean square error and r2 score, were employed to avoid overfitting and ensure model effectiveness. the model demonstrated a high accuracy level of 0.97 suggesting its ability to predict results that mirror real-life situations closely. the current research highlights how artificial intelligence (ai) can improve energy efficiency and control in schools and universities. by using abilities, administrators and energy managers can effectively organize resources regulate demand, and distribute energy. apart, from cost savings this proactive energy management strategy promotes sustainability. reduces harm. this method contributes to a future by cutting down on energy wastage and greenhouse gas emissions. 8. conclusion in this study we present a dataset focusing on energy consumption in an university campus, in iraq. the main aim of the research was to leverage ai techniques to develop models for predicting 540 0 200 400 600 800 1000 0 20 40 60 80 100 120 140e n er gy c o n su m p ti o n ( k w /h ) working days energy prediction )2023(88 -67, p.p. 4khwarizmi engineering journal, vol. 19, no. -al reem omar mahdi 85 energy usage patterns and supporting energy management practices. the use of ai algorithms and machine learning methods has significantly improved the estimation of energy consumption in buildings. by training ai models on data, weather conditions, occupancy rates, building sizes, and other relevant factors it becomes possible to forecast energy usage trends over time. the results from training the model were highly promising with an mse (mean squared error) of 0.16 and an r2 score of 0.97 achieved. a neural network model was employed to estimate the energy consumption in buildings at the university of baghdad by considering input variables and adjusting training, to validation ratios accordingly. the study focuses on utilizing intelligence to predict energy usage in a university building, to reduce energy consumption. an illustration of how ai could forecast energy demand was shared by the al khwarizmi college of engineering in iraq. the models created in the research successfully captured the connections between factors affecting energy usage leading to precise forecasts and proactive decision making. to enhance ai-powered energy prediction models, 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(2024) 76-88، صفحة 1، العدد20المجلد جلة الخوارزمي الهندسيةم ريم عمر مهدي 88 للتعلم اآللي للتنبؤ بالطاقة المستهلكة في كلية الهندسة الخوارزمي، learn-scikitتطبيق بغداد، العراق **وسام سعدي خضير *ريم عمر مهدي كلية الهندسة الخوارزمي/ جامعة بغداد /الميكاترونكس قسم الهندسة**،* omarreem07@gmail.com:البريد االلكتروني* wisam@kecbu.uobaghdad.edu.iq:البريد االلكتروني** الخالصة أنحاء العالم. إن الخصائص الفيزيائية للمبنى، وفعالية أنظمة التدفئة والتبريد، وأنشطة السكان، واستدامة % من استهالك الطاقة في جميع 40تمثل المباني . يعد تقدير الطلب المبنى ليست سوى عدد قليل من العوامل العديدة التي تؤثر على استهالك الطاقة في المبنى. من الصعب جدًا تقدير متطلبات الطاقة للهيكل حفوري. المبنى أمًرا حيويًا لزيادة االستدامة وتطوير مصادر الطاقة المستدامة لخفض انبعاثات ثاني أكسيد الكربون الناتجة عن حرق الوقود األ على الطاقة في م جمع بيانات ت ( الواقعة في كلية الهندسة الخوارزمي في بغداد.uobتم في هذه الدراسة شرح الطاقة المستخدمة في قاعة المحاضرات في جامعة بغداد ) ي المبنى المذكور الطقس ومعلومات تشييد المباني لفترة محددة ووضعها في مجموعة بيانات محددة. وتم استخدام تلك البيانات لمعرفة قيمة استهالك الطاقة ف ت التعلم اآللي. على وجه الخصوص، تم لتنفيذ خوارزميا learn-scikitتسمى pythonباستخدام الذكاء االصطناعي وتحليل البيانات. يتم استخدام مكتبة ( للتنبؤ باالستهالك. وتكمن أهمية هذا العمل في التنبؤ بكمية الطاقة المستهلكة. يمكن mlpregressorاستخدام خوارزمية تراجع بيرسبترون متعدد الطبقات ) لمنهجية المستخدمة إمكانية التنبؤ بأداء الطاقة في المباني التعليمية باستخدام استخدام نتائج هذا العمل للتنبؤ بالطاقة التي يستهلكها أي مبنى قبل بنائه. وتبين ا ( إلعطاء أعلى دقة. تم aiالنتائج السابقة وتدريب النموذج عليها، وتعتمد دقة التنبؤ على كمية البيانات المتوفرة للتدريب على خطوات الذكاء االصطناعي ) ، على التوالي.²rو rmseلـ 0.97و 0.16( ووصلنا إلى ²r( ومعامل التحديد )rmseربع الخطأ )التحقق من التنبؤ باستخدام جذر متوسط م 26 al-khwarizmi engineering journal al-khwarizmi engineering journal, vol.3, no1,pp 26-39, (2007) an investigation into the performance of counter rotating floating ring journal under different working conditions. dr. basim a. abass dr. adel a. alwan mustafa b. hunain lecturer asst. prof. graduate student babylon university babylon university babylon university (received 26 september 2006 ; accepted 20 december 2006) absract: the steady state performance of the counter rotating floating ring journal bearing is analyzed with isothermal finite bearing theory. the effect of different parameters affecting the performance of the bearing (namely speed ratio, clearance ratio and radii ratio), have been investigated. the load carrying capacity of the bearing increasing with decreasing the radii ratio (r2/r1) of the ring and clearance ratio (c1/c2), in the other hand, the coefficient of friction increases with increasing the clearance and radii ratios, while decreases with incre4asing the bearing to journal speed ratio (γ). it is shown during this work that different operating conditions are greatly enhanced the performance of such bearings. keywords: counter rotating, floating ring, isothermal performance. introduction: circular journal bearing with journal and bearing counter rotating at the same speed has no load capacity. an example of counter rotating journal bearing system can be found in the inter shaft bearing of the front drive turbo shaft engine. since the experimental work done by pinkns (1962) it seems that there is a very little work dealing with the performance of counter rotating bearings. the effect of counter rotating speed of the sleeve on the performance of the counter rotating floating ring bearing has been investigated by yeon – min, et al (2001). a floating ring journal bearing is a special type of hydrodynamic lubricated journal bearing in which a ring is maintained floating in the lubricating fluid between the shaft journal and rigid housing. many works have been carried out by many workers dealing with the performance of this type of bearing. orcutt (1968), mokhtar (1981), tanaka .and hori (1972), wilcock (1983). a suitability of floating ring journal bearing for automotive application was tested by dong and zhao (1990). san andres and kerth (2004) put forward a computation programs to study the effect of variable oil viscosity on the performance of the floating ring journal bearing in order to improve the design and performance of turbo chargers. the purpose of this paper is to study the effect of different working parameters, namely, speed ratio, clearance ratio, and radii ratio, on the performance of counter rotating floating ring journal bearing. isothermal finite bearing theory is used for this work. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. basim a. abass /al-khwarizmi engineering journal ,vol.3, no.1, pp 26-39 (2007) 27 numerical analysis: fig(1) shows a schematic diagram of counter rotating floating ring journal bearing with the coordinate system used in this analysis. the journal rotates with a constant angular velocity (ωj) about its center (oj), while the bearing rotates with a constant angular velocity (ωb) about its center (ob). the ring rotate about its center (or) with an induced angular velocity (ωr).rotational direction of the journal is set to be positive. the pressure distribution through the oil films of the bearing can be evaluated from the solution of the classical reynolds equation which can be written as   kk kkkk kk h z ph z p r h r                                     1 33 6 1 …. (1) where: kk=1, ωkk=ωj and ωkk+1=wr (journal – ring oil film). kk=2, ωkk=ωr and ωkk+1=ωb (ring – bearing oil film). the oil film thickness can be evaluated as:   kkkk ch  cos1 ….(2) the boundary condition at each film is: 0kkp at 0kk (at position of maximum film thickness). 0         kk kk p p  at kkckk   ( at film rapture boundaries ). 0kkp at 0z and lz  (at axial ends). where: kkckk   180 the fluid film forces are obtained by integrating the pressure distribution in radial and tangential directions to give the load components in these directions as follows:   kk l kkr c dzdrpw            0 0 cos   ….(3)   kk l kkt c dzdrpw            0 0 sin   …. (4) and the load carrying capacity of the bearing can be calculated as :      22 kktkkrkk www  ….(5) the attitude angle for both oil films (inner and outer oil films) can be evaluated as:  kkr t kk w w         1tan ….(6) the reference sommerfeld number can be expressed from the following expression,:2 1 1 1 1              c r w lr s j   ….(7) the frictional torque acted at the inner and outer surfaces of the floating ring can be calculated as:   dzdxuu hx ph rt l x rjr c 1 0 0 11 1 1 1 1 2                       (8)   dzdxuu hx ph rt l x brr c 2 0 0 22 2 2 2 2 2                       (9) to calculate the steady state performance of the bearing it is necessary to found out the steady state equilibrium, positions of the journal and the ring centers. the following equations for force and moments are hold for equilibrium state; for force balance:w1=w2 ….(10) and for torque balance:tr1=tr2 ….(11) this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. basim a. abass /al-khwarizmi engineering journal ,vol.3, no.1, pp 26-39 (2007) 28 method of solution: the pressure distribution through the oil films can be obtained by solving equation (1) iteratively at each film of the bearing. the physical domain was discretized by a mesh size of (50) in circumferential direction, (20) across the half width of the bearing the reynolds equation is solved for each grid. the differences equations derived from this discritization are solved by successive over relaxation scheme. the iteration is continued until the following inequality is satisfied: 5 , 1 ,, 10      n ji n ji n ji p pp ….(12) where (n) and (n-1) denotes two consecutive iterations, and (pi,j) is the nodal pressure at point (i,j) in which the sign of ( i,j ) represent the grid number in circumferential and axial directions respectively. the oil pressure obtained used to evaluate the load components in radial and tangential directions. hence the load carried by the bearing can be obtained from equation (5). the results obtained must be satisfied the equilibrium conditions, namely equation (10) and equation (11). the solution was continued until the following inequalies are satisfied simultaneously. tr1-tr2<10-3 ….(13) w1-w2<10-3 ….(14) results and discussion: the computer program prepared to solve the governing equations of the problem is tested by comparing the obtained results with that published by yeon – min et al. (2001). the flowchart for the computer program can be shown in fig. (2). hence figures (3 – 6) shows a comparison between the results obtained in this work and that published by the above mensioned worker. it seems that there is a good agreement between the results. the induced ring speed decreases with decreasing the speed ratio (γ) as shown in fig. (7), if the counter rotating of the bearing increases from zero, the ring rotating in the same direction with the journal in early stage, is decelerated to be stationary at γ = -0.5 (the induced ring speed close to zero), and then accelerated to the rotational direction of the bearing. the decrease in ring speed increases with higher values of clearance ratio (c1/c2), since the bearing speed is dominant in this case as shown in fig. (8,9). it can also be deduced that the ring speed become nearly stationary in broad rang of reference sommerfeld number (s) at bearing to journal speed ratio of ( -0.5) and clearance ratio of (0.5) as shown in fig. (8,9). at c1/c2 > 0.5, the induced ring speed is slightly decreases with increasing the reference sommerfeld number for lower values of reference sommerfeld number (s) then it seems to be constant at higher values of (s). the induced ring speed rotating in the same direction with the bearing and becomes higher as the ring become closer to the bearing as shown in fig.(7), since the bearing speed is dominant in the two figures above. fig. (10) shows that the ring speed decreased with increasing the radii ratio of the ring (r2/r1), which suggested that the ring become heavier in this case. the correlation between journal – ring eccentricity ratio (ε1) and ring – bearing eccentricity ratio (ε2) for different speed ratio shown in fig. (11). it is clear that as the counter rotating speed of the bearing increases, the journal – ring eccentricity ratio (ε1) increases for a given value of ring – bearing eccentricity ratio (ε2). since the ring speed decreases in this case. the journal – ring eccentricity ratio (ε1) increases with increasing the clearance ratio (c1/c2) as shown in fig. (12). this is true in order to maintain the equilibrium conditions of the bearing and to ensure that the bearing is hydrodynamically lubricated. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. basim a. abass /al-khwarizmi engineering journal ,vol.3, no.1, pp 26-39 (2007) 29 it is clear that as the bearing to journal speed ratio (γ) decreases the attitude angle () increases for any specified value of reference sommerfeld number as shown in fig. (13). the attitude angle is affected by the ratio (wt/wr) in equation (6). the ratio of (wt/wr) has a great effect on the pressure of the lubricant film, where any increases in this pressure, by increases the bearing to journal speed ratio (γ), tends to increase the ratio of (wt/wr). the attitude angle (ψ) seems to have a lower value as the clearance ratio (c1/c2) decreases since the journal speed became dominant in the case as shown in fig. (14), while the attitude angle (ψ) decrease as the radii ratio (r2/r1) increases as shown in fig. (15), since the bearing speed became dominant in this case. the coefficient of friction increases with increasing the speed ratio (γ), since the friction force of the inner and outer surface of the ring depend on ωj+ωrandωr+ωbrespectively as shown in figures (16,17) . it is clear that as the clearance ratio decreases, the coefficient of friction decreases for any specified value of the reference sommerfeld number (s). the coefficient of friction (f(r1/c1)) is affected by │ωj+ ωr│ and │ωr+ ωb│. the decrease in the clearance ratio (c1/c2) increases the ring speed, suggesting that the coefficient of friction becomes lower when the ring be closer to the journal conclusions: the steady state performance of the counter rotating floating ring journal bearing is analyzed with isothermal finite bearing theory. it is shown that the performance of such bearing is greatly affected by different operating conditions. the ring speed seems to increase with higher values of clearance ratio and decrease with increasing the radii ratio. the journal – ring eccentricity ratio increases with increasing the counter rotation speed in order to maintain the equilibrium condition of the bearing. the attitude angle increases with decreasing the bearing to journal speed and clearance ratios. it is also increases with decreasing the radii ratio of the floating ring. the coefficient of friction increases with increasing the clearance, while decreases with increasing the bearing to journal speed ratio. it is clear that the counter rotating floating ring journal bearing can have considerable load carrying capacity at the same counter rotating speeds, by choosing the appropriate performance parameters rather than the conventional counter rotating bearing. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. basim a. abass /al-khwarizmi engineering journal ,vol.3, no.1, pp 26-39 (2007) 30 fig. (1) counter –rotating floating ring journal bearing oj or ob x y w1 w2 rj r1 r2 h1 h2 b r j e1 e2 journal ring sleeve ob bearing center or ring center oj geometric center of journal this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. basim a. abass /al-khwarizmi engineering journal ,vol.3, no.1, pp 26-39 (2007) 31 start read rj, l, nj, μ, c1, c2, r2/r1, nb assume ε1=0.01 assume ε2=0.05 assume nr=nb calculate pi,j for the inner oil film. calculate the error using equation (12). if error < 10-5 1 yes x=x+1 no 235 figure (2) flowchart. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. basim a. abass /al-khwarizmi engineering journal ,vol.3, no.1, pp 26-39 (2007) 32 1 calculate pi,j for the outer oil film. calculate the error using equation (12). if error < 10-5 yes no x=x+1 calculate w2, tr2 for the outer oil film using equation (5) and (9) respectively. if │w1-w2│< 10-3 and │tr1-tr2│< 10-3 no yes nr=nr+1 if nr < nj yes no ε2= ε2+0.005 3 2 calculate s, f, ψ 4 calculate w1, tr1 for the inner oil film using equation (5) and (8) respectively. figure (2) continued. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. basim a. abass /al-khwarizmi engineering journal ,vol.3, no.1, pp 26-39 (2007) 33 4 print ε1, ε2,nr/nj, s, f, ψ ε2= ε2+0.005 if nr < nj yes no 5 end figure (2) continued. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. basim a. abass /al-khwarizmi engineering journal ,vol.3, no.1, pp 26-39 (2007) 34 fig.(3). comparison between cheong and kim and program results for eccentricity ratio of inner film versus sommerfeld number; at c1/c2=1; r2/r1=1.25 and  =-0.5 0.01 0.10 1.00 10.00 0.00 0.20 0.40 0.60 0.80 1.00  1 s program result cheong and kim 0.00 0.40 0.60 0.80 1.00 0.20 0.01 0.10 1.00 10.00 fig.(4). comparison between cheong and kim and program results for eccentricity ratio of outer film versus sommerfeld number; at c1/c2=1; r2/r1=1.25 and  =-1 0.01 0.10 1.00 10.00 0.00 0.20 0.40 0.60 0.80 1.00 s ε 2 0.01 0.10 1.00 10.00 program result cheong and kim 0.00 0.40 0.60 0.80 1.00 0.20 fig.(5). comparison between cheong and kim and program results for dimensionless ring speed versus sommerfeld number; at c1/c2=1; r2/r1=1.25 and  =0.0 0.01 0.10 1.00 10.00 -2.00 -1.00 0.00  s 0.01 0.10 1.00 10.00 -1.0 -2.0 0.0 program result cheong and kim fig.(6). comparison between cheong and kim and program results for dimensionless ring speed versus sommerfeld number; at c2/c1=1; r2/r1=1.25 and  =-1 0.01 0.10 1.00 10.00 -2.50 -1.50 -0.50 0.50 α s program result cheong and kim 0.01 0.10 1.00 10.00 -2.50 -1.5 -0.50 0.50 this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. basim a. abass /al-khwarizmi engineering journal ,vol.3, no.1, pp 26-39 (2007) 35 0.01 0.10 1.00 10.00 -0.5 -0.4 -0.3 -0.2 -0.1 0.0 r2/r1=1.25 =-1 c1/c2=0.5 c1/c2=1 c1/c2=1.5 fig. (9). computed results sommerfeld number versus ring to journal speed ratio for various values of clearance ratios. 0.01 0.10 1.00 10.00 -0.7 -0.6 -0.5 -0.4 -0.3 -0.2 -0.1 0.0 c1/c2=1 =-1 r2/r1=1.25 r2/r1=1.5 fig. (10). computed results sommerfeld number versus ring to journal speed ratio for various values of radii ratios. ss   γγ 0.01 0.10 1.00 10.00 -0.7 -0.6 -0.5 -0.4 -0.3 -0.2 -0.1 0.0 0.1 0.2 0.3 r2/r1=1.25 c1/c2=1.5 =0 =-0.5 =-1 fig. (7). computed results sommerfeld number versus ring to journal speed ratio for various values of bearing to journal speed ratios. 0.01 0.10 1.00 10.00 -0.10 -0.05 0.00 0.05 0.10 r2/r1=1.25 =-0.5 c1/c2=0.5 c1/c2=1 c1/c2=1.5 fig. (8). computed results sommerfeld number versus ring to journal speed ratio for various values of clearance ratios. s s  γ γ γ γ this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. basim a. abass /al-khwarizmi engineering journal ,vol.3, no.1, pp 26-39 (2007) 36 γ ss ψ ( d eg re e) ψ ( d eg re e) γ γ γ 0.0 0.2 0.4 0.6 0.8 1.0 0.0 0.2 0.4 0.6 0.8 1.0 r2/r1=1.25 =-0.5 c1/c2=0.5 c1/c2=1 c1/c2=1.5 fig.(12). correlation between eccentricity ratio of inner oil film and eccentricity ratio of outer oil film for various values of clearance ratio. 0.0 0.2 0.4 0.6 0.8 1.0 0.0 0.2 0.4 0.6 0.8 1.0 r2/r1=1.25 c1/c2=1.5 =0 =-0.5 =-1 fig.(11). correlation between eccentricity ratio of inner oil film and eccentricity ratio of outer oil film for various values of bearing to journal speed ratios. 0.01 0.10 1.00 10.00 20 30 40 50 60 70 80 90 100 r2/r1=1.25 c1/c2=1.5 =0 =-0.5 =-1 fig. (13). attitude angle versus sommerfeld number for various values of bearing to journal speed ratios. 0.010 0.100 1.000 10.000 0 10 20 30 40 50 60 70 80 90 r2/r1=1.25 =-0.5 c1/c2=0.5 c1/c2=1 c1/c2=1.5 fig.(14). attitude angle versus sommerfeld number for various values of clearance ratios. ε2 ε2 ε 1 ε 1 γ γ γ γ γ this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. basim a. abass /al-khwarizmi engineering journal ,vol.3, no.1, pp 26-39 (2007) 37 fig. (15). attitude angle versus sommerfeld number for various values of radii ratios. 0.01 0.10 1.00 10.00 0.1 1.0 10.0 100.0 r2/r1=1.25 =0 c1/c2=0.5 c1/c2=1 c1/c2=1.5 fig. (16). friction coefficient versus sommerfeld number for various values of clearance ratios. 0.010 0.100 1.000 10.000 20 30 40 50 60 70 80 90 c1/c2=1.5 =-0.5 r2/r1=1.25 r2/r1=1.5 s s f( r 1/ c 1 ) ψ ( d eg re e) γ γ 0.01 0.10 1.00 10.00 0.1 1.0 10.0 100.0 1000.0 r2/r1=1.25 =-1 c1/c2=0.5 c1/c2=1 c1/c2=1.5 fig. (17). friction coefficient versus sommerfeld number for various values of clearance ratios. s f( r 1/ c 1 ) γ this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. basim a. abass /al-khwarizmi engineering journal ,vol.3, no.1, pp 26-39 (2007) 38 references: dong, x., and zhao, z., 1990, "experimental and analytical research on floating – ring bearing for engine applications", journal of tribology, january, vol. 112, pp. 119 – 122. mokhtar, m. o. a., 1981, "floating ring journal bearing: theory, design and optimization", tribology international, april, pp. 113 – 119. orcutt, f. k., and ng. c.w. 1968, "steady – state and dynamic properties of the floating ring journal bearing", asme journal of lubrication technology, vol. 90, pp. 1 – 10. pinkuse, o., 1962, "counter rotating journal bearing", asme journal of basic engineering, vol. 84, pp. 110 – 115. san andres and j. kerth, 2004, "thermal effect on the performance of floating ring bearings for turbochargers", proc. instri. mech. engrs., part j., j. engineering tribology, vol. 218, pp.437 – 450. tanaka, m., and hori, y., 1972, "stability characteristics of floating bush bearings", asme journal of lubrication technology, july, pp. 248 – 259. wilcock, d. f., 1983, "load carrying efficiency of floating ring journal bearings", asme, journal of lubrication technology, oct., vol. 105, pp. 605 – 608. yeon – min cheong and kyung – wood kim, 2001, "operating characteristics of counter – rotating floating ring journal bearings", kstle international journal, december, vol. 2, no. 2, pp. 127 – 132. nomencleature: h oil film thickness (m). p oil film pressure (n/m2). µ oil viscosity (pa.s).  eccentricity ratio. w load carrying capacity of the bearing (n). l bearing length (m). α ring to journal speed ratio. c clearance (m). f coefficient of friction. tr frictional torque (n.m). subscripts: b referring to bearing. c referring to the position of cavitations. j referring to journal. i,j grid number in circumferential and axial direction, respectively. kk =1 referred for journal – ring oil – film. =2 referred for ring – bearing oil – film. r referring to floating ring. α angular position of end of pressure curve beyond minimum film thickness. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr. basim a. abass /al-khwarizmi engineering journal ,vol.3, no.1, pp 26-39 (2007) 39 دراسة أداء سلوك المساند عكسیة الدوران ذات الحلقة العائمة تحت ظروف عمل مختلفة مصطفى باقر ھنین عادل عباس علوان.د باسم عجیل عباس .د طالب دراسات علیا مساعد .أ مدرس جامعة بابل جامعة بابل جامعة بابل :الخالصة باستخدام نظریة المساند . ذات الحلقة العائمة في الحالة المستقرةفي ھذا البحث تم تحلیل أداء المساند عكسیة الدوران نسبة (تم دراسة مختلف الظروف التي تؤثر على عمل المسند والتي یمكن تسمیتھا . المحددة وبدرجات حراریة ثابتة ع زیادة نسبة سعة حمل المحمل تزداد م). ونسبة أنصاف األقطار, نسبة الخلوص,السرعة بین البوشة الخارجیة والمحور بزیادة نسبة أنصاف أقطار الحلقة و معامل االحتكاك یزداد, و من ناحیة أخرى,أنصاف أقطار الحلقة و نسبة الخلوص وجد بان لھذه المتغیرات تأثیر كبیرا , خالل ھذا العمل.نسبة الخلوص بینما یقل بزیادة نسبة سرعة المحور و الركیزة .على أداء ھذا النوع من المساند this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 19, no. 1, march, (2023) p. p. 8198 expired colxacillin, amoxicillin, and ceflaxin drugs as inhibitors for low carbon steel corrosion in sodium chloride ameer jawad* shatha k. muallah** kafa khalaf hammud*** *,** department of bio-chemical engineering / al-khwarizmi engineering college/ baghdad university/ baghdad/ iraq ***ministry of science and technology/baghdad/ iraq *email: amir.jawad74@yahoo.com **email: drshathamuallah@gmail.com ***email: kafaa_khalaf@yahoo.com (2022 november 16 2022; accepted augest 22received ) https://doi.org/10.22153/kej.2023.11.003 abstract the ability to inhibit corrosion of low carbon steel in a salt solution (3.5%nacl) has been checked with three real expired drugs (cloxacillin, amoxicillin, ceflaxin) with variable concentrations (0, 250, 500, 750) mg/l were examined in the weight loss. the inhibition efficiency of the cloxacillin 750 mg/l showed the highest value (82.8125 %) and the best inhibitor of the rest of the antibiotics. the different concentrations of cloxacillin drug (0, 250, 500, 750) mg/l and temperature (25, 35, 45, 55) oc were studied as variables with potentiodynamic polarization, scanning electron microscopy (sem) for surface morphology and electrochemical impedance spectroscopy (eis) depending on current values and the resistance of charge to calculate the inhibition efficiency. the main observations of these tests were that polarization curves showed a mixed-type inhibition of expired cloxacillin. the inhibition efficiency increased with increasing cloxacillin concentration but not with increasing temperature. keywords: polarization, inhibitor, expired drugs, cloxacillin, amoxicillin, ceflaxin, salt corrosion. 1. introduction due to the good mechanical properties of low carbon steel alloy, this material is the generally used in processing plants and household applications, availability, and comparatively low cost[1, 2]. chloride-containing solutions, like seawater, are in most cases, corrosive because the depolarization impacts carbon ions, the main case is the low resistance of low carbon steel to corrosion [3, 4]. it has been found that one of the preferable ways of keeping metals from corrosion comprises the use of expired antibiotics as corrosion inhibitors. the prevention or decreasing of corrosion impacts on metals like low carbon steel by using expired antibiotics is a method created because of the toxicity of many corrosion inhibitors, therefore; the researchers in the corrosion field selected compounds that are friendly to the environment, safe, and non-toxic such as pharmaceutical drugs [5]. their capability to make a complex with metal ions on the metal surfaces through their functional groups. perfectly the drugs soluble in the water besides their high purity and inexpensively as expired antibiotics are important factors in choosing expired drugs as corrosion inhibitors [6]. these characteristics would support the employment of expired drugs as corrosion inhibitors in various aqueous solutions. generally, expired antibiotics are large surface area materials, including functional groups (n) with an effective cover above the surface of lowcarbon steel for the adsorption process[7, 8, 9]. mailto:amir.jawad74@yahoo.com mailto:kafaa_khalaf@yahoo.com https://doi.org/10.22153/kej.2023.11.003 ameer jawad al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 8198 (2023) 82 the following table gives a comparison of (inhibition efficiency) ie percentage between various antibiotics (table 1.). table 1, examples of pharmaceutical inhibitors with their ie percentage[1]. inhibitor sample medium ie % carvedilol carbon steel hcl 98.94 amifloxacin mild steel 17.1 enrofloxacin mild steel 18.3 cefotaxime mild steel 90.0 a b sa b s n s o h n o nh2 o ho amoxicillin c16h19n3o5s m.wt. 365.4 gm/mole n o nh o nh2 s o ho cephalexin c16h17n3o4s m.wt. 347.4 gm/mole n o cl o n h n o s o oh cloxacillin c19h18cln3o5s m.wt. 435.9 gm/mole ho fig.1. chemical structure of the expired drugs used in the test with molecular weights for each one. here, the main goal is to test the corrosion– inhibition relationship as its rate and its effects on the low carbon steel in a medium of (nacl) with the absence and presence of an inhibitor and on another occasion when the inhibitor is used in different concentrations with different temperatures. the inhibitors, as shown in the experimental section, were real expired antibiotics because of their cost and economical serving forwarding limitation of environmental pollution with pharmaceutically active compounds. 2. experimental methods 2.1 materials the sample is low carbon steel with a chemical composition of “weight %” (0.18 carbon, 0.9 manganese, 0.05 sulphur and the rest is iron). the expired drugs "cloxacillin, amoxicillin, and ceflaxin” were tested as corrosion inhibitors. the antibiotics were collected from (samara`a drugs industry, iraq, samara) as a pure expired antibiotics for two years. sodium chloride solution nacl as a corrosive medium from cdh company, india. 2.2 weight loss method the experiments of this method were done by immersion of low carbon steel specimens with size (3x3x1) cm3 in 3.5% nacl (2 g of salt in 60 ml of water) solution for five days. also, low carbon steel was immersed in the same corrosive media with the presence of one of the three bioactive inhibitors (250, 500, 750) mg/l for a period of 5 days. the obtained results were ameer jawad al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 8198 (2023) 83 tabulated in table 2. using the equations listed below [10]. the specimens are cleaned before and after the test using a different aluminum paper of various degrees (p40, p50, p100, p140, p220). 𝐼𝐸% = 𝜃 ∗ 100 … (1) 𝐼𝐸% = 1 − 𝑊𝑖𝑛ℎ 𝑊𝑓𝑟𝑒𝑒 …(2) 𝑐𝑜𝑟𝑟𝑜𝑠𝑖𝑜𝑛 𝑟𝑎𝑡𝑒 = 𝑤𝑒𝑖𝑔ℎ𝑡 𝑙𝑜𝑠𝑠 (𝑔𝑟𝑎𝑚𝑠)∗𝑘 𝑎𝑙𝑙𝑜𝑦 𝑑𝑒𝑛𝑠𝑖𝑡𝑦 𝑔 𝑐𝑚3∗𝑒𝑥𝑝𝑜𝑠𝑒𝑑 𝑎𝑟𝑒𝑎∗𝑒𝑥𝑝𝑜𝑠𝑢𝑟𝑒 𝑡𝑖𝑚𝑒(ℎ𝑟) …(3) where ie% is the inhibition efficiency, 𝜃 is the surface coverage while 𝑊𝑖𝑛ℎ and 𝑊𝑓𝑟𝑒𝑒 are the weight loss in the presence and absence of inhibitor respectively. 2.3 electrochemical tests from weight loss results, the inhibitor cloxacillin shows the best results in protecting metal surfaces due to the high molecular weight of the inhibitor [11]. cloxacillin was chosen to complete the other tests as sem and electrochemical tests. the electrochemical tests were done in a three-electrode cell with platinum as the counter electrode, saturated calomel as the reference electrode (sce), and low carbon steel as the working electrode. open circuit potentials ocp were carried out in the electrolyte before running the electrochemical measurements [12]. the specimens were immersed in the electrolyte for 30 min, followed by ocp measurement for 60 min. when calculating the corrosion current, the method can be used is the stern-geary by extrapolation of anodic and cathodic tafel lines to the point that gives logicorr and the conformable corrosion potential (ecorr) for inhibitor-free salt and different concentration of the antibiotics used. all practical experiments were done at 25◦c [13]. 2.3.1 tafel polarization a potentiostat was used in this test, and kinetics parameters were found from tafel curves such as corrosion current (icorr), cathodic tafel slope (βc), anodic tafel slope (βa), corrosion potential ecorr and ie%. the experiment was done by using three concentrations of cloxacillin as corrosion inhibitor (0, 250, 500, and 750) mg/l, with four degrees of temperature (25, 35, 45, and 55) ◦c for each concentration of inhibitor. 2.3.2 electrochemical impedance spectroscopy (eis) electrochemical impedance spectroscopy (eis) was carried out at open circuit potential in the frequency range of (10-1 -105) hz. eis plots are found in the nyquist and bode diagrams. the electrochemical studies were carried out with an electrochemical cs 310 corrtest workstation, iraq, baghdad, university of baghdad (al khwarizmi engineering college). fig. 2. randle circuit in impedance spectroscopy. 2.4 surface study surface morphology as an indicator of how much salts affect the pieces of low carbon steel and how the corrosion inhibitors resist the corrosion and save the surface is tested by a scanning electron microscope (sem). the specimens with cloxacillin (inhibitor) were chosen for sem by the tescan mirah3 instrument (dansh bryan company, tehran, iran ) where the scanned area was (1-6) μm. 3. result and discussion 3.1 weight loss test weight loss measurements of low carbon steel samples were reported after 5 days for three real expired drugs (cloxacillin, amoxicillin, ceflaxin) as shown in table 2. the maximum ie, % at cloxacillin 750 mg/l showed the highest value (82.8125 %) and the best inhibitor of the rest of the antibiotics. table 3 showed the weight loss in the absence of inhibitors. ameer jawad al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 8198 (2023) 84 table 2, weight loss results of the three bioactive inhibitors. [w free = 0.064 gm] table 3, weight loss results in the absence of inhibitor. 3.2 electrochemical tests potentiodynamic polarization measurements have been carried out. potentiodynamic polarization curves for low carbon steel metal in 3.5% nacl solution with different concentrations of cloxacillin expire drug are displayed in figures (3-5) with different temperature (25, 35, 45, 55)oc. cloxacillin was chosen for the test of tafel curves because it gave the best result in the weight loss experiment as 82% ie%. may be noticed table 4, the anodic and cathodic tafel slopes (βa, βc) curves with the presence of inhibitors and which turns lower current density (icorr). it can be observed in the presence of inhibitors both the anodic and cathodic curves are shifting towards lower current density. which reveals that inhibitor molecules are adsorbed on the metal surface. although the corrosion potential of the metal nearly remain constant, there is a slight shift towards more positive potential at higher concentrations with respect to the corrosion potential observed in the absence of inhibitor. figures (3-6) show the effect of inhibitor concentration and temperature on current density and voltage with four temperature degrees (25, 35, 45, 55)◦c respectively. it is noticed that the same concentration of the inhibitor with different temperature sometimes increases and other decreases, but at 750 mg/l of cloxacillin at 35 oc gives minimum corrosion rate. table 4, electrochemical study of cloxacillin inhibitor name antibiotic conc., mg/l w inh, gm surface coverage ( θ) ie, % cloxacillin 250 0.023 0.640625 64.0625 500 0.021 0.671875 67.1875 750 0.011 0.828125 82.8125 amoxicillin 250 0.033 0.484375 48.4375 500 0.030 0.53125 53.1250 750 0.021 0.671875 67.1875 ceflaxin 250 0.034 0.46875 46.8750 500 0.031 0.515625 51.5625 750 0.028 0.562500 56.2500 solution kind original weight (g) final weight (g) the difference in weight(g) corrosion rate (mm/a) nacl 7.03 6.9834 0.064 0.182 conc., mg/l temp.oc ecorr (v/sce) i corr*10-6(a/cm2) corrosion rate (mm/a) βa(v/dec) βc(v/dec) ie% blank 25 -0.95073 15.5 0.18200 267.47 112.79 35 -0.72475 21.4 0.25097 86.564 456.7 45 -0.86188 69.2 0.81135 252.57 156.08 55 -0.77695 15.1 0.17756 77.437 231.38 250 25 -0.78254 6.91 0.081114 71.752 200.77 55.3 35 -0.84599 4.60 0.053967 82.62 147.35 78.5 45 -0.84487 6.07 0.071241 88.361 150.83 91.2 55 -0.83344 4.46 0.05821 77.581 140.9 70.5 500 25 -0.77939 6.50 0.076252 71.197 212.99 58.0 35 -0.80915 7.07 0.082971 73.877 137.09 66.9 45 -0.79384 11.7 0.13686 70.256 211.44 83.1 55 -0.82055 8.67 0.10175 74.232 173.69 42.7 750 25 -0.75942 1.95 0.22825 67.527 67.527 87.4 35 -0.85093 3.51 0.041119 86.244 86.244 83.6 45 -0.84281 5.58 0.065418 79.704 79.704 91.9 55 -0.84777 5.70 0.066828 88.548 88.548 62.4 ameer jawad al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 8198 (2023) 85 fig. 3. variation of inhibitor concentration on current density and voltage at 25oc. fig. 4. variation of inhibitor concentration on current density and voltage at 35oc fig. 5. variation of inhibitor concentration on current density and voltage at 45oc ameer jawad al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 8198 (2023) 86 fig. 6. variation of inhibitor concentration on current density and voltage at 55 oc. 3.3 electrochemical impedance spectroscopy (eis) in these experiments, cloxacillin was used with 3.5% nacl solution at different temperature degrees by using an electrical circuit called randle circuit where cdl is called double-layer capacitor, rct is the charge transfer resistance and rsol is the solution resistance as shown in table 4 [14]. experimental results of this method are shown in figures (7-14) nyquist, bode and (log(f)-log(z)) and (f)-phase) diagrams of lowcarbon steel, which were obtained in 3% of nacl solution in the absence and presence of various concentrations of cloxacillin are shown. it can be seen from figures (7a-14a) the nyquist plot of the metal shows a depressed semi-circular shape. the obtained graphs (7b,c-14b,c) showed how bio inhibitor affected the real and imaginary resistance introduced where zʺ is the imaginary resistance, zʹ is the real resistance, f is the frequency and θ◦ is the phase values. (a) 50 -50 -150 -250 -350 -450 -550 -650 -750 -100 0 100 200 300 400 500 600 700 z' '/ω cm 2 z'/ωcm 2 blank concentration of inhibitor fitresult ameer jawad al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 8198 (2023) 87 (b) (c) fig. 7. the eis test for blank concentration of inhibitor at 25◦c with the fitting result. . (a) nyquist plot, (b, c) bod (log versus |z|), and phase angle (log f versus ∝𝟎) plots. (a) 20 0 -20 -40 -60 -80 -100 10 -2 10 -1 10 0 10 1 10 2 10 3 10 4 10 5 10 6 θ ° f/hz blank concentration of inhibitor fitresult 200 0 -200 -400 -600 -800 -1000 -1200 -1400 -200 0 200 400 600 800 1000 1200 1400 z' '/ω cm 2 z'/ωcm 2 blank concentration of inhibitor fitresult ameer jawad al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 8198 (2023) 88 (b) (c) fig. 8. the eis test for blank concentration of inhibitor at 35◦c with the fitting result. . (a) nyquist plot, (b, c) bod (log versus |z|), and phase angle (log f versus ∝𝟎) plots. (a) 20 0 -20 -40 -60 -80 -100 10 -2 10 -1 10 0 10 1 10 2 10 3 10 4 10 5 10 6 θ ° f/hz blank concentration of inhibitor fitresult 100 -100 -300 -500 -700 -900 -1100 -200 0 200 400 600 800 1000 z' '/ω cm 2 z'/ωcm 2 blank concentration of inhibitor fitresult ameer jawad al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 8198 (2023) 89 (b) (c) fig. 9. the eis test for blank concentration of inhibitor at 45◦c with the fitting result.. (a) nyquist plot, (b, c) bod (log versus |z|), and phase angle (log f versus ∝𝟎) plots. (a) 40 20 0 -20 -40 -60 -80 -100 10 -2 10 -1 10 0 10 1 10 2 10 3 10 4 10 5 10 6 θ ° f/hz blank concentration of inhibitor fitresult 50 -50 -150 -250 -350 -450 -550 -100 0 100 200 300 400 500 z'' /ω cm 2 z'/ωcm 2 blank concentration of inhibitor fitresult ameer jawad al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 8198 (2023) 90 (b) (c) fig. 10. the eis test for blank concentration of inhibitor at 55◦c with the fitting result. (a) nyquist plot, (b, c) bod (log versus |z|), and phase angle (log f versus ∝𝟎) plots. (a) 20 0 -20 -40 -60 -80 -100 10 -2 10 -1 10 0 10 1 10 2 10 3 10 4 10 5 10 6 θ ° f/hz blank concentration of inhibitor fitresult 100 -100 -300 -500 -700 -900 -1100 -1300 -200 0 200 400 600 800 1000 1200 z' '/ω cm 2 z'/ωcm 2 750 mmg inhibitor fitresult ameer jawad al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 8198 (2023) 91 (b) (c) fig. 11. the eis test for 750 mg/l concentration of inhibitor at 25◦c with the fitting result. (a) nyquist plot, (b, c) bod (log versus |z|), and phase angle (log f versus ∝𝟎) plots. (a) 20 0 -20 -40 -60 -80 -100 10 -2 10 -1 10 0 10 1 10 2 10 3 10 4 10 5 10 6 θ ° f/hz 750 mmg inhibitor fitresult 50 -150 -350 -550 -750 -950 -200 0 200 400 600 800 z' '/ω cm 2 z'/ωcm 2 750 mmg fitresult ameer jawad al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 8198 (2023) 92 (b) (c) fig. 12. the eis test for 750 mg/l concentration of inhibitor at 35◦c with the fitting result. (a) nyquist plot, (b, c) bod (log versus |z|), and phase angle (log f versus ∝𝟎) plots. (a) 20 0 -20 -40 -60 -80 10 -2 10 -1 10 0 10 1 10 2 10 3 10 4 10 5 10 6 θ ° f/hz 750 mmg fitresult 50 -50 -150 -250 -350 -450 -550 -650 -100 0 100 200 300 400 500 600 z'' /ω cm 2 z'/ωcm 2 750 mmg fitresult ameer jawad al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 8198 (2023) 93 (b) (c) fig. 13. the eis test for 750 mg/l concentration of inhibitor at 45◦c with the fitting result. (a) nyquist plot, (b, c) bod (log versus |z|), and phase angle (log f versus ∝𝟎) plots. (a) 40 20 0 -20 -40 -60 -80 -100 10 -2 10 -1 10 0 10 1 10 2 10 3 10 4 10 5 10 6 θ ° f/hz 750 mmg fitresult 50 -50 -150 -250 -350 -450 -550 -650 -100 0 100 200 300 400 500 600 z'' /ω cm 2 z'/ωcm 2 750 mmg fitresult ameer jawad al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 8198 (2023) 94 (b) (c) fig. 14. the eis test for 750 mg/l concentration of inhibitor at 55◦c with the fitting result. (a) nyquist plot, (b, c) bod (log versus |z|), and phase angle (log f versus ∝𝟎) plots. it was noticed that the impedance spectra exhibit a semi-circle caused by the frequency dispersion effect which means that the corrosion of low carbon steel in nacl solution was controlled by a charge transfer process[15]. the diameter of the capacitive loop in the presence of an inhibitor was larger than in the absence of the inhibitor (blank concentration) and increased with inhibitor concentration. this observation conflicts with the increasing impedance of inhibited metal with increasing concentration. this irregular behavior is generally caused by the roughness and inhomogeneity of the alloy surface [5]. the charge transfer resistance rct value increased with increasing of concentration. but it turns out that the capacitance values (cdl) of the double-layer decrease, and this decrease is expected in the presence of the local dielectric constant. this causes an increase in the thickness of the electrical double layer [16]. it is observed from table 5 the 750 mmg concentration of cloxacillin at 45oc give the maximum ie% and maximum rct . 40 20 0 -20 -40 -60 -80 -100 10 -2 10 -1 10 0 10 1 10 2 10 3 10 4 10 5 10 6 θ ° f/hz 750 mmg fitresult ameer jawad al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 8198 (2023) 95 table 5, values of the eis test for absence and presence of cloxacillin. conc.mg/l temp.c rct ie% cdl 𝝁𝒇 blank 25 174.65 0.543 blank 35 600.01 0.345 blank 45 347.95 0.231 blank 55 135.86 0.124 750 25 835 88.04 0.431 750 35 955 83.78 0.335 750 45 1135 90.46 0.211 750 55 795 60.76 0.105 3.4 surface analysis the sem micrographs for low carbon steel in presence and absence of 750 mg/l of cloxacillin are shown in figure 15(a-d). it is obviously seen from figure 15a that the metal surface is strongly damaged in the absence of the inhibitor. in figure 15d showed that the film is stable and protective which support the results of electrochemical measurements which are discussed above. (a) (b) (c) (d) fig. 15. sem of (a) blank (b) 250 mg/l (c) 500 mg/l (d) 750 mg/l of cloxacillin. 3.5 the mechanism of inhibition the adsorption of expired antibiotics are to be the first step at the alloy/solution interface done in the mechanism of corrosion inhibition in the salt solution medium[17]. this becomes acceptable for the first step during the adsorption of an antibiotics drug as organic materials on the surface of the alloy, and this involves by substituting one or more water molecules adsorbed on the surface of the alloy[18], as in equation below[19] : organic (inhibitor) + xh2o→ organic ( adsorbed) + x h2o … (3) ameer jawad al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 8198 (2023) 96 4. conclusion the studied of expired antibiotics drugs, (cloxacillin, amoxicillin, cephalexin) can be used as good organic inhibitors for corrosion in salt solution on the low carbon steel metal in 3% nacl as a salt solution. cloxacillin has better inhibition, because of its high molecular weight, molecular surface, and functional groups as compared to the two others expired antibiotic drugs. increasing the concentration of antibiotics increased the inhibition efficiency and decreased corrosion rate. the minimum corrosion rate appears at temperature 35◦c with 750 mg/l concentration of cloxacillin. eis plots indicated that rct values increase whereas cdl values decrease in presence of cloxacillin. the changes in the impedance parameters confirmed the strong adsorption of the inhibitor on the steel surface. sem studies revealed that cloxacillin form protective surface film. 5. references [1] a. s. fouda, m. a. el morsi, and t. el mogy, “studies on the inhibition of carbon steel corrosion in hydrochloric acid solution by expired carvedilol drug,” green chem. lett. rev., vol. 10, no. 4, pp. 336–345, 2017, doi: 10.1080/17518253.2017.1380236. 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(2023) 81-98، صفحة 1، العدد19لدمجلة الخوارزمي الهندسية المج امير جواد خلف 98 المضادات الحيوية المنتهية الصالحية )الكولكساسبلين و االموكسيسيلين والسيفالكسين( الحاصل للحديد القليل الكاربون في محلول ملح كلوريد الصوديوم للصدأكمثبطات مير جواد خلف* شذى كاظم عبد اللطيف** كفاء حمود خلف***أ *،**قسم الهندسة الكيميائية االحيائية/ كلية الهندسة الخوارزمي/ جامعة بغداد/ العراق بغداد/ العراق***وزارة العلوم والتكنولوجيا/ amir.jawad74@yahoo.com :البريد االلكتروني* drshathamuallah@gmail.com**البريد االلكتروني: kafaa_khalaf@yahoo.com***البريد االلكتروني: الخالصة ة أدوية منتهية % كلوريد الصوديوم( بثالث 3,5تم التحقق من القدرة على منع التآكل في الفوالذ منخفض الكربون في محلول ملح ) حص والف (eis) كيميائيةوالتحليل الطيفي للمقاومة الكهرو الكهربي،واستقطاب الجهد الوزن،الصالحية. تم اختبار التثبيط باستخدام إنقاص موكسيسيلين، تم فحص ثالثة عقاقير منتهية الصالحية )كلوكساسيلين، أ الوزن،في إنقاص . لتشكل السطح (sem) المجهري اإللكتروني ة التركيز لكل المضادات تزداد مع زياد الطريقة تبين أن كفاءة التثبيط ( ملجم / لتر بهذه750، 500، 250، 0سيفالكسين( بتركيزات متغيرة ) سيلين أفضل مثبط لبقية وهذا جعل الكلوكسا (،٪82.8125ملجم / لتر من الكلوكساسيلين أعلى قيمة لكفاءة التثبيط ) 750الحيوية. حيث أظهر .المضادات الحيوية ( درجة 55، 45، 35، 25( ملجم / لتر ودرجة الحرارة )750، 500، 250، 0ساسيللين )تمت دراسة تأثير التراكيز المختلفة لعقار كلوك لقيم الحالية ومقاومة الشحنة ااعتمادًا على (eis) مئوية كمتغيرات مع االستقطاب الديناميكي الفعال والتحليل الطيفي للمقاومة الكهروكيميائية وكساسيللين ا من نوع الكلذه االختبارات هي أن منحنيات االستقطاب أظهرت تثبيطًا مختلطً كانت المالحظات الرئيسية له. لحساب كفاءة التثبيط .منتهي الصالحية. زادت كفاءة التثبيط مع زيادة تركيز الكلوكساسيلين ولكن ليس مع زيادة درجة الحرارة mailto:amir.jawad74@yahoo.com*البريد mailto:amir.jawad74@yahoo.com*البريد mailto:drshathamuallah@gmail.com mailto:kafaa_khalaf@yahoo.com this is an open access article under the cc by license : al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 21, no. 3, september, (2025), pp. 111 application of aqueous two-phase system in the extraction of invertase enzyme from potato tubers using peg8000/potassium phosphate meaad h. kadhim1*, khalid w. hameed2, and hameed b. mahood3 1,2 department of biochemical engineering, al-khwarizmi college of engineering, university of baghdad, baghdad, iraq 3 centre for sustainable cooling, school of chemical engineering, university of birmingham, united kingdom *corresponding author’s email: miad.abadi2205@kecbu.uobaghdad.edu.iq (received 17 september 2024; revised 4 november 2024; accepted 10 november 2024; published 1 september 2025) https://doi.org/10.22153/kej.2025.11.003 abstract an aqueous two-phase system (atps) is a clean alternative for traditional aqueous-organic solvent extraction systems. this technique has proven to be highly effective for extracting and separating mixtures of biomolecules. the present investigation involved the extraction of the invertase enzyme from potato tubers utilizing atps. the system applied was: polyethylene glycol 8000 combined with dipotassium diphosphate (peg8000/pph). the study investigated the impact of five factors, namely temperature, peg8000 concentration, dipotassium phosphate concentration, ph, and the addition of sodium chloride (nacl) or magnesium sulphate (mgso4) as a catalyst, on the recovery percentage (%rec) and partition coefficient (ke) of the invertase of the invertase enzyme in atps over the study period. the system achieved a maximum recovery (%rec) of 87.52% and a maximum partition coefficient (ke) of 7.01 at a temperature of 10°c, with a peg8000 concentration of 1.5 g/10 ml, a dipotassium phosphate concentration of 2.4 g/10 ml, and a ph of 10. after the addition of neutral salts, the system achieved a maximum %rec of 91.9% and a maximum ke of 11.34 under the same optimal conditions, and a concentration of mgso4 of 1 g/10 ml. keywords: aqueous two-phase system; enzymes; plant source; potato tuber. 1. introduction certain features of bioproducts are lost during their extraction from downstream utilizing commercial techniques like liquid-liquid extraction (also known as the aqueous-organic system). the use of an aqueous two-phase system (atps) is an environmentally friendly and bioproduct-safe alternative [1], [2]. the atps was accidentally discovered by martinus willem beijerinck in 1896, but its practical application was not implemented until the 1970s [1], [2]. in recent years, interest in atps systems and their research has become broader. they include several types of chemicals, such as polymer-polymer or polymer salt systems that can be combined, to perform several functions [3]. this process is preferred over alternative extraction processes due to its ability to bear the cost, its suitability to the environment, and its versatility in extracting a wide range of compounds [3], [4]. water contributes to the stabilization and separation of biomolecular structures in the two phases of atps [5], [6], [8], while other liquidliquid extraction processes can cause damage to biological products due to harsh process conditions and the use of organic solvents [4], [5]. atps is a combination of two distinct materials. they may include either a salt and a polymer, such as dipotassium phosphate (k2hpo4) and peg, or two polymers, such as peg and dextran. in order to form two phases, the polymer/salt concentration must be mailto:miad.abadi2205@kecbu.uobaghdad.edu.iq https://doi.org/10.22153/kej.2025.11.003 meaad h. kadhim1 al-khwarizmi engineering journal, vol. 21, no.3, pp. 111 (2025) 2 higher than the critical concentration, below which the two phases cannot be achieved at lower concentrations. critical concentrations depend on the molecular weight of the polymer and the type of salt [5], [7]. however, there are biphasic systems, consisting of short-chain alcohols and ionic liquids [7], [9], [10]. researchers have examined several forms of atps to understand and analyze their ability to separate, eliminate, and disinfect molecules and biomolecules [9]. although atps have many advantages, there is complexity in the partitioning of biomolecules in these systems, making it difficult to predict their behavior. in addition, the interaction between the system and biomolecular factors, such as ph and temperature, is of great importance [11], [12]. the enzyme targeted in this research is called invertase, also called beta-fructofuranosidase, which is a glycoprotein whose function is to break down the end parts of beta-fructofuranoside molecules [13]. it is one of the important enzymes in food processing and is responsible for the convert of sucrose by producing d-fructose and d-glucose. it operates best at ph 4.5 and is stable at 50°c [13]. invertase is often used in the food industry to convert sucrose into fructose syrup. it is also used in the manufacture of sucrose biosensors and in the paper, pharmaceutical and cosmetic industries [14, 15]. many plants, including potato, carrot, tomato, tobacco, sugarcane, and bamboo, are major plant sources of invertase production [16], [17]. in addition, there is research showing the presence of invertase in several yeasts, including saccharomyces cerevisiae [20], candida utilis [21], pichia anomola [22], and a few fungi, mostly aspergillus niger and neurospora sp. [23] – [25]. the ideal ph for acidic invertase is usually between 3.5-5.0, while the alkaline ph is 7.0-8.0 [18], [19]. fresh potatoes contain high invertase activity, which has been shown to increase during cold storage [26], suggesting that potato tubers are a useful source for research into invertase characterization and purification. although various methods exist to purify invertase from different plant sources, these techniques are considered timeconsuming and costly [26] – [29]. albertson invented it in the early 1950s to distinguish amongst proteins, nucleic acids, and cells [30]. this technology has advantages such as efficiency, provides rapid separation with little denaturation, high mass transfer, specific partitioning, and low cost. as a result, it finds application in various biotechnology sectors [31], [32]. the aim of this study is to determine the optimal operating parameters for extracting the invertase enzyme from native iraqi potato tubers utilizing the taguchi method as an experimental design. the factors studied that effected on the extraction of invertase from potatoes were: temperature (10 – 40 °c), ph (8 – 10), concentration of potassium phosphate and peg8000 (1.5 – 2.4 g/10 ml), and concentration of the support nacl or mgso4 (0 – 2 g/10 ml). 2. materials and experimental work 2.1. materials dipotassium phosphate (k2hpo4), copper sulphate (cuso4), and sodium carbonate (na2co3) were obtained from central drug house ltd., india, and sodium chloride (nacl) was supplied from alpha chemika, india. sucrose and polyethylene glycol (peg8000), 3,5-dinitrisalicylic acid (dns), sodium hydroxide (naoh) and bovine serum albumin (bsa) were purchased from himedia laboratories pvt. ltd., india. folin reagent from sisco research laboratories pvt. ltd. (srl) in india. as for potatoes, they were purchased from local markets in iraq. high-quality reagents were used in the analysis. deionized and double-distilled water, which was obtained from the laboratories of the department of biochemical engineering, was used in this study. 2.2. experimental work 2.2.1. crude extract preparation fresh potatoes were cleaned with distilled water after removing their peels well. after that, 20 grams of potatoes were weighed, cut into small pieces, and mixed in 50 millimoles of cold citrate buffer with a ph of 4 for one minute at a temperature of 4 degrees celsius. the mixture was filtered through five layers of cheesecloth, and the remaining solids were separated by centrifugation at 5000 rpm for ten minutes at 4°c. the supernatant layer was taken and considered as the crude enzyme extract. the specific activity of the crude extract was checked and it was 20.11 units/mg. figure 1 shows the experimental procedure that was performed in the laboratory. meaad h. kadhim1 al-khwarizmi engineering journal, vol. 21, no.3, pp. 111 (2025) 3 fig.1. experimental setup lab work progress. 2.2.2. aqueous two-phase partitioning from the experimental study, it was found that the dipotassium phosphate should be mixed with the crude extract to obtain a greater extraction rate, so the system consists of dipotassium phosphate stock solutions (1.5-2.4 g) per 10 ml of crude extract and (1.5-2.4 g) of peg8000 per 10 ml of distilled water. the two solutions were mixed for two minutes and using a vortex. to obtain the two phases, the mixture can be left for 2-3 hours under the influence of the force of gravity, but for speed, the mixture was separated into two phases using centrifugation at 6000 rpm for 10 minutes. the upper phase was the peg8000 solution, and correspondingly the lower phase was the salt solution. after extraction, in equilibrium, there was the raffinate phase (rf), which is called the phase that loses the enzyme, while the phase that gains the enzyme is called the extraction phase (ex). on the basis of previous studies, the selected system parameters were temperature, ph, concentrations of polymer (peg800), and dipotassium phosphate [33] – [37]. the upper phase was carefully isolated from the lower phase using a pasteur pipette. measurements of the sizes of distinct phases were taken. portions of the phases were examined for protein quantification and enzyme analysis. partition parameters, such as partition coefficient, recovery percent, and specific activity, were calculated using formulas derived from previous studies [38] – [40]. protein content (kp) or partition coefficient (ke) is the definition of the invertase partition coefficient in two-phase aqueous systems. this coefficient indicates the ratio of the enzyme concentration in the extraction phase to the ratio of the concentration of the raffinate phase when the system is in equilibrium, as shown in eqs. 1, 2 and 3 [41]. 𝐾𝑃 = 𝐶𝐸𝑥 𝐶𝑅𝑓 , …(1) 𝐾𝐸 = 𝐴𝐸𝑥 𝐴𝑅𝑓 , …(2) or 𝐾𝐸 = % 𝑅𝑒 𝑐 1−% 𝑅𝑒 𝑐 , …(3) where cex and crf are the total protein concentrations in mg/ml of the extract and raffinate phases respectively, aex and arf are the enzyme activities in u/ml of the extract and raffinate phases, respectively. in order to assess the efficacy of the purification process, it is necessary to measure the activity of the enzyme, specifically referred to as the enzymespecific activity (sa, expressed in u/mg protein), recovery % and partition coefficient of enzyme (ke), additionally, the calculations were performed based on the provided equations [42]. invertase activity (u/ml) = 𝐴 × 𝑉 € × 𝑡 × 𝑣 , …(4) where: a: absorbency at 540 nm v: total volume of reaction mixture in (2 ml) €: enzyme constant (0.01) t: incubation time (30 min) v: volume of crude used in (0.2 ml) sa = 𝐼𝑛𝑣𝑒𝑟𝑡𝑎𝑠𝑒  𝑎𝑐𝑡𝑖𝑣𝑖𝑡𝑦 𝐶𝑅𝑓 , …(5) recovery % = (1 − 𝐴𝑅𝑓 𝐴𝑖𝑛 ) × 100 , ...(6) where ain is the initial activity of enzyme in u/ml. 2.2.3. determining invertase activity miller's method for determining invertase activity in plants was described by miller in 1959. the assay mixture used in this method includes 0.8 ml of substrate, 50 mmole sucrose in citrate buffer with a ph of 4.5, and 0.2 ml of enzyme diluted to the desired concentration. then, at 37°c, the mixture was incubated for 30 minutes. next, the reaction was terminated by adding 1 ml of dns reagent (3,5-dinitrosalicylic acid) and heating for five minutes. the solution was then cooled to ambient temperature using an ice bath and the amount of reducing sugars was measured using meaad h. kadhim1 al-khwarizmi engineering journal, vol. 21, no.3, pp. 111 (2025) 4 spectrophotometry at a wavelength of 540 nm [43]. one unit of invertase activity is defined as the amount of enzyme that converts 1 micromole of sucrose into glucose within one minute, at a temperature of 37°c and a ph of 4.5. 2.2.4. protein concentration determination the lowry method was applied to calculate protein concentration [40], including the solutions that were used to determine the protein: • solution (1): 2% na2co3 in 500 ml of 0.1m naoh, 10 g of na2co3 were dissolved. • solution (2): 2% sodium potassium tartrate in a small amount of distilled water (e.g. 20 ml), 2 g of sodium and potassium tartrate were dissolved, then the volume was completed to 100 ml by distilled water. • solution (3): 1% cuso4 1 g of cuso4 was dissolved in 100 ml of distilled water. • solution (4): it was prepared immediately by mixing 98 ml of solution (1) with 1 ml of solution (2) and 1 ml of solution (3). • solution (5): bovine serum albumin (bsa) the solution was prepared by gradually dissolving 0.01 g of bsa in distilled water and then adjusting the volume to 100 ml using distilled water. • solution (6): folin-reagent 1 ml of folin was diluted in 2 ml of distilled water (1:2 v/v). by lowry's method the protein concentration was determined [40]. the solutions that had been prepared previously were used and the protein was determined as follows: from the original concentration, the required concentration of bsa 100 μg/ml was prepared. to each tube 4.0 ml of solution 4 was added, then left for 10 minutes. then, 0.4 ml of folin reagent (solution 6) was added to each tube, shaken well, and then left for 30 minutes. the absorbance was recorded at 600 nm, and tube 1 was used as the blank tube. figure 2 shows the standard curve of bsa using the lowry method. 3. results and discussions the protein content and specific activity of the crude extract were measured as 5.11 mg and 20.11 u/mg, respectively. the minitab v17.0 was used to design the set of experiments using the taguchi method, where each parameter had four levels. the study initially focuses on studying the effect of four factors: temperature, ph, and the concentration of peg8000 and k2hpo4 (pph). after establishing the ideal conditions that produce the highest extraction rate, (nacl or mgso4), which are natural salts, were introduced to monitor their effect. tables 1 shows the number of experiments with the parameters and the results of recovery percent (%rec) and partition coefficient (ke). fig. 2. bsa standard curve 3.1. temperature impact as the temperature increases, enzymes undergo changes in their conformation, stability, and conformation. therefore, the temperature was set between 10 – 40oc. next, by dividing the enzyme activity at different temperatures by the total enzyme activity and then multiplying the result by 100, the relative activity percentage was calculated. the effect of temperature on the invertase extraction rate as well as its partition coefficient was studied as shown in figures 3 and 4a. without adding the neutral salts (nacl or mgso4), it is clear that the percentage of %rec and ke recorded the lowest percentage at 40°c, where it reached 71.4% and 2.49, respectively, and they increased between 10 and 30 degrees celsius, where the highest values were recorded, which were 75.4% and 3.06 for %rec and ke, respectively. the effect of temperature on the compositional behavior is complicated by the interaction between its component parts, namely electrostatic and hydrophobic forces. the results show a positive comparison with previous reports. typically, invertase derived from different plants show the highest level of activity at 37 °c [44] – [46]. studies on the effect of temperature on invertase activity and stability have shown that these properties are strongly influenced by the location of the enzyme and the temperature. for example, soluble invertase meaad h. kadhim1 al-khwarizmi engineering journal, vol. 21, no.3, pp. 111 (2025) 5 extracted from wheat germ demonstrated maximum activity at 37 oc and maintained 60% of its activity after exposure to 50 oc for 4 minutes [47]. furthermore, singh and knox (1984) reported notable differences in the thermal stability of different forms of plant invertase [45]. table 1, number of experiments of the system (peg8000/pph) according to taguchi method with their results of %rec and ke. no. temp oc ph peg8000 g/10 ml % rec ke k2hpo4 (pph) g/10 ml 1 10 8 1.5 1.5 74.68 2.94 2 10 8.7 1.8 1.8 72.94 2.69 3 10 9.4 2.1 2.1 74 2.84 4 10 10 2.4 2.4 79.58 3.89 5 20 8 1.8 2.1 66.29 1.96 6 20 8.7 1.5 2.4 68.19 2.14 7 20 9.4 2.4 1.5 83.38 5.01 8 20 10 2.1 1.8 76.58 3.26 9 30 8 2.1 2.4 72.46 2.63 10 30 8.7 2.4 2.1 70.88 2.43 11 30 9.4 1.5 1.8 71.51 2.51 12 30 10 1.8 1.5 85.91 6.09 13 40 8 2.4 1.8 74.99 2.99 14 40 8.7 2.1 1.5 71.67 2.52 15 40 9.4 1.8 2.4 69.93 2.32 16 40 10 1.5 2.1 68.35 2.15 3.2. ph impact using hydrochloric acid or sodium hydroxide the ph was adjusted. in many industrial applications, ph stability is another important measure when selecting enzymes as biocatalysts. the ph value range is determined from 8.0 to 10.0 for the peg8000/k2hpo4 system at room temperature. in figures 3 and 4a, the effect of ph changing from 8 10 recorded increasing in a %rec in the range (72.2% 77.8%), which indicates that more enzymes will be recovered from the crude extract. the lowest percentages recorded for %rec and ke were 70.9% and 2.43, respectively, at ph 8.7. these results are consistent with those of [48] – [50]. to interfere this phenomenon, in general, bioproducts can be divided into two phases based on the differences in their charges and surface characteristics. the aqueous solution's ph can cause this to alter. an electric force is created when protein molecules with a positive net charge attempt to yank electrons from other proteins. however, the electric force is reduced and the proteins obtain a net negative charge when the ph is higher than the phindicator or potential isoelectric point (pi); otherwise, it becomes positive. no net charge is realized when the ph and pi values are the same [51]. 3.3. impact of potassium phosphate concentration in a two-phase system, the concentration of potassium phosphate salt (pph) used is an important factor that greatly affects enzyme partitioning. from experience, the amount of pph in the solution has an effect on the amount of enzyme extracted into the atps and how strongly it breaks down the atps. according to [49], [50], researchers found that in the peg/salt system the recovery rate and partition coefficient increase with increasing salt concentration. when examining figures 3 and 4b, it is clear that the high salt content concentration, enhances the extraction process, and increases the partition coefficient. an increasing the salt concentration from 1.5 g/10 ml to 2.4 g/10 ml resulted in an increase in %rec of enzyme from 70.8% to 77% and thus an increase in partition coefficient from 2.42 to 3.34, as shown in figures 3 and 4. meaad h. kadhim1 al-khwarizmi engineering journal, vol. 21, no.3, pp. 111 (2025) 6 3.4. peg concentration impact the concentration of peg8000 was further studied in terms of its ability to form the phase. this research revealed that this concentration significantly affects the rate and regularity of the invertase enzyme partitioning, influencing the amount of recoverable invertase as shown in figure 3 and 4b. when the concentration increased from 1.5 g/10 ml to 2.1 g/10 ml, %rec of the invertase enzyme decreased from 79% to 72.4%. these results are consistent with [52], suggesting that an increase in peg8000 concentration decreases %rec. the proteins in the atps migrate from the lower phase to the upper phase, automatically increasing the partition coefficient. the polymer and enzyme interact differently; occasionally, the contact is more hydrophobic, allowing the proteins to separate more readily. the protein's ability to recover is hindered and the partition coefficient (ke) is significantly reduced when the peg concentration is elevated [53]. fig. 3. impact of (temperature, ph, concentrations of peg8000 and k2hpo4) on the %rec. fig. 4. effect the parameters on the %rec of the invertase enzyme in 3 dimensions. (a): effect of temperature and ph; (b) concentration effect of pph salt and peg8000. 3.5. impact of nacl and mgso4 as the last step, supporting agents were added to show their effect and to enhance protein partitioning and its recovery rate. the hydrophobic phase contains proteins with a higher concentration of hydrophobic anions or cations, and the opposite is also true [49]. figure 5 shows the effect of adding of two different types of nacl and mgso4 salts. these results are obtained under optimal conditions: temperature = 10 oc, ph 10, peg8000 concentration = 2.4 g/ 10 ml, and k2hpo4 concentration = 2.4 g/10 ml. these salts enhance the separation process due to differing hydrophobicity of their ions. one phase preferentially concentrates the more hydrophobicity ions, whereas another phase accumulates less hydrophobic ions [54], [55]. figure 5 clearly illustrates that the %rec and then ke varies greatly with the addition of nacl and mgso4. the %rec increases from 87 to 89.4% for nacl and from 87.2 to 91.9% for mgso4 as the salt concentration increases from 0 to 1 g/10 ml. beyond this point, %rec and then ke begin to decline as the meaad h. kadhim1 al-khwarizmi engineering journal, vol. 21, no.3, pp. 111 (2025) 7 salt concentration continue to increase. the results obtained are consistent with those of [56], [57]. fig. 5. impact concentration of nacl and mgso4 on the %rec and ke. 4. conclusions through the results obtained, the system was found to be highly effective in purifying and extracting invertase when preparing both peg8000 (1.5 g/10 ml) and k2hpo4 (2.4 g/10 ml) at ph 10 and a temperature of 10 oc. in addition, the inclusion of mgso4 at a concentration of 1 g/10 ml further enhances the process. atps offer a costeffective, safe, and straightforward method for protein purification, demonstrating superior efficiency to other conventional techniques. the distribution of invertase in peg8000/pph system demonstrated that the plant enzyme can be extracted to the concentrated phase with the salt at the lower phase. this finding indicates that peg concentration, type and concentration of salt, temperature, ph, and the use of natural salts as catalysts influenced the partitioning of invertase significantly. as a result, the enzyme recovery rate and partition coefficient were 91.9% and 11.34, respectively. an extremely high %rec suggests that no more than one stage is required for efficacy recovery acknowledgement the authors appreciate the supportive suggestions and technical assistance provided by the laboratories of the department of biochemical engineering, al-khwarizmi college of engineering, university of baghdad. references [1] albertsson p. å.: partition of cell particles and macromolecules in polymer two-phase systems. advances in protein chemistry, vol. 24, pp. 309-341 (1970) https://doi.org/10.1016/s00653233(08)60244-2 [2] grilo a. l., raquel aires-barros m. and azevedo a. m.: partitioning in aqueous twophase systems: fundamentals, applications and trends. separation & purification reviews, vol. 45, pp. 68-80 (2016) doi: 10.1080/15422119.2014.983128 [3] hatti-kaul r. , "aqueous two-phase systems: methods and protocols," springer science & business media, vol. 11 (2008) [4] iqbal m., tao y., xie s., zhu y., chen d. and yuan z.: aqueous two-phase system (atps): an overview and advances in its applications," biological procedures online, vol. 18, pp. 1-18 (2016) [5] asenjo j. a. and andrews b. a.: aqueous twophase systems for protein separation: a perspective. journal of chromatography a 1218, vol. 49, pp. 8826-8835 (2011) doi: 10.1016/j.chroma.2011.06.051 [6] mendes, m.s., rosa, m.e., ramalho, f., freire, m.g. and e silva, f.a..: aqueous twophase systems as multipurpose tools to improve biomarker analysis. separation and purification technology, p.123875. 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[57] shad z, mirhosseini h, hussin asm, forghani b, motshakeri m, manap mya. aqueous twophase purification of α-amylase from white pitaya (hylocereus undatus) peel in polyethylene glycol/citrate system: optimization by response surface methodology. biocatal agric biotechnol [internet]. 2018; 14: 305–13. available from: https://doi.org/10.1016/j.bcab.2018.01.014 http://dx.doi.org/10.1016/j.procbio.2008.04.011 https://doi.org/10.1016/j.bcab.2018.01.014 ( 2025) 1-11، صفحة 3، العدد21مجلة الخوارزمي الهندسية المجلد ميعاد حيدر كاظم 11 تطبيق النظام المائي ثنائي الطور في استخالص إنزيم اإلنفرتيز من درنات البطاطس باستخدام peg8000/ فوسفات البوتاسيوم 3بالسم ماهود ، حميد2خالد وليد حميد *، 1ميعاد حيدر كاظم 2،1قسم الهندسة الكيميائية األحيائية، كلية الهندسة الخوارزمي، جامعة بغداد ، العراق 3مركز استدامة التبريد، مدرسة الهندسة الكيميائية ، جامعة برمنجهام، المملكة المتحدة miad.abadi2205@kecbu.uobaghdad.edu.iq االلكتروني: *البريد المستخلص بديالً نظيفًا ألنظمة استخالص مذيبات المياه العضوية التقليدية. أثبتت هذه التقنية فعاليتها العالية في استخالص (atps) يعد النظام المائي ثنائي الطور إيثيلين المطبق: هوالبوليالنظام atps وفصل مخاليط الجزيئات الحيوية. تضمن البحث الحالي استخالص إنزيم اإلنفرتيز من درنات البطاطس باستخدام ، peg8000 هي درجة الحرارة، وتركيز: خمسة عوامل في هذه الدراسة تأثير بحثت . (peg8000/pph) مع ثنائي فوسفات البوتاسيوم 8000جاليكول كمحفزعلى نسبة االسترداد (mgso4) أو كبريتات المغنيسيوم (nacl) وتركيز فوسفات ثنائي البوتاسيوم، واألس الهيدروجيني، وإضافة كلوريد الصوديوم (%rec) ، ومعامل الفصل (ke) إلنزيم اإلنفرتيز في atps سترجاععلى قدر من االأخالل فترة الدراسة حقق النظام (%rec) على أو %87.52بنسبة 2.4مل، وتركيز فوسفات ثنائي البوتاسيوم 10جم/ 1.5قدره peg8000 درجات مئوية، مع تركيز 10عند درجة حرارة 7.01قدره (ke) معامل فصل وقدره ke على قيمة لمعامل الفصلأو %91.9وقدره rec% على نسبة استردادأ . بعد إضافة األمالح المحايدة، حقق النظام10مل، ودرجة حموضة 10جم/ .مل 10جم/ 1قدره mgso4 في ظل نفس الظروف المثالية، وتركيز 11.34 mailto:miad.abadi2205@kecbu.uobaghdad.edu.iq*البريد this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 20, no. 3, september, (2024), pp. 2035 a comprehensive survey of push recovery techniques for standing and walking bipedal robots ibrahim altameemi * *robotics engineering department, worcester polytechnic institute (wpi) *email: ialtameemi@wpi.edu (received 12 may 2024; revised 23 july 2024; accepted 29 july 2024; published 1 september 2024) https://doi.org/10.22153/kej.2024.07.002 abstract bipedal robots, which mimic human or animal motion, are expected to perform numerous tasks, such as delivering healthcare, conducting search and rescue missions in dangerous environments and serving industrial applications. bipedal robots are required to interact with objects or people in their surroundings while performing their planned tasks. the main challenge faced by these robots is their ability to maintain balance in the presence of disturbances, such as external pushing forces applied to them and uneven terrains. therefore, a push recovery control system that enables these robots to preserve stability while executing their intended tasks must be developed. this study investigates several push recovery control algorithms for bipedal robots operating in static (standing) or dynamic (walking) modes when faced with disturbances. the study further assesses the literature based on three factors: 1) the dynamic model used to represent the robot’s behaviour, 2) the control methods and 3) the required sensors. moreover, this review paper emphasises the challenges that must be tackled in future research. these issues include the ability of bipedal robots to adapt rapidly to changing conditions in dynamic scenarios, the substantial energy consumption they require and the delays that arise from the complex and nonlinear structure of their movements. hence, this research suggests some recommendations for effectively tackling these difficulties. 1) sensory feedback approaches with machine learning algorithms should be employed to develop adaptable balance control systems that quickly learn from and react to different disturbances in real time. 2) control algorithms that optimally balance stability and energy efficiency, such as predictive control algorithms that emulate the natural reflexes of humans, should be developed. 3) hierarchical control systems should be used to partition the balance control problem into smaller stages, thus reducing the latency issues related to solving complex nonlinear equations. keywords: push recovery control; bipedal robots, cop; zmp, centroidal moment pivot; dynamic stability; lipm; whole-body dynamics 1. introduction ongoing and comprehensive research has been undertaken on bipedal robots because of their versatile capabilities in performing a wide range of tasks, including search and rescue missions, healthcare delivery and industrial applications. these tasks necessitate the engagement of bipedal robots with their surroundings, which encompass objects and people. the main challenge that these robots encounter is performing specified tasks while maintaining balance in the presence of external disturbances, such as a pushing force, uneven terrains or other factors. hence, a push recovery control system that allows bipedal robots to preserve stability must be developed. figure 1 demonstrates the push recovery control in which a humanoid robot counteracts a pushing force by executing a wider lateral step than existing models. this review paper aims to conduct a comprehensive examination of the current push recovery control techniques employed in bipedal mailto:ialtameemi@wpi.edu https://doi.org/10.22153/kej.2024.07.002 https://doi.org/10.22153/kej.2024.07.002 ibrahim altameemi al-khwarizmi engineering journal, vol. 20, no.3, p.p. 2035 (2024) 21 robots under static (standing) or dynamic (walking) conditions while accounting for environmental disturbances. this research conducts a comparative analysis and categorisation of studies by focusing on three primary factors: the dynamic model employed to depict the robot’s movement, the method utilised for balance control and the sensors necessary for operation. this study examines and analyses previous research to identify the obstacles that prevent bipedal robots from performing actual tasks in real-world settings. these issues encompass the ability of bipeds to adjust quickly to unanticipated dynamic environments, the significant energy consumption and the nonlinearity and complexity of dynamics. moreover, this study proposes recommendations for future research to tackle the challenges and improve the functionality of bipedal robots in performing real-world tasks. this review paper seeks to contribute to the continuous progress and innovation in bipedal robotics by clarifying previous accomplishments, highlighting obstacles and suggesting future research areas. fig. 1. a humanoid robot recovers from a push (the red arrow) [1]. 2. background 2.1. principles of balancing of bipedal robots the zero moment point (zmp) is the point where the sum of moments about the centre of pressure (cop) is equal to zero, whereas the cop is the point at which the resultant ground reaction force is normal [2-4]. a bipedal robot is stable if the zmp remains within the boundaries of the support polygon. the zmp and cop coincide when they are inside the support polygon. notably, cop is always within the boundaries of the support polygon. if it reaches the edge, the foot will initiate rotation, thus causing the robot to be on the edge of balance. meanwhile, the zmp can go beyond the support polygon; in this case, it would be called a fictitious zmp [5]. these terms are crucial stability criteria in bipedal robotics that guide the development of control techniques and algorithms for maintaining balance. the centroidal moment pivot (cmp) point [6] denotes the point at which the ground reaction force vector must act to produce no torque about the centre of mass (com). as a result, the rate of change of the angular momentum is strongly correlated with the distance between cmp and zmp. when the moment about the com is zero, the cmp coincides with the zmp. however, when the com moment is nonzero, the extent of separation between the cmp and zmp is equal to the magnitude of the horizontal component of the moment about the com divided by the normal component of the ground reaction force [6]. 2.2. dynamics modelling in bipedal robots many dynamic modelling methods for bipedal robots provide significant insights at different levels of complexity. the linear inverted pendulum model (lipm) [7,8] and its extensions, such as the lipm with a flywheel (lipfm), help explain basic locomotion principles. centroidal dynamics models [9] explain robot motion more accurately by considering mass distribution and its influence on movement. the maximum level of reliability is achieved through whole-body dynamics [10], which considers the complex interactions among all body parts. this approach allows for accurate simulations and precise control methods. 2.2.1. simplified models linear inverted pendulum model (lipm): lipm has been extensively employed as a simplified model for analysing the dynamics of robots in the field of push recovery control [7,8, 11,12]. in lipm modelling, a set of multiple rigid bodies can be simplified and treated as a single mass. the total forces exerted on a system result in a change in linear momentum �̇�, which is equivalent to the acceleration of the system’s com (according to newton’s law). at the same time, when the moments around the com are added together, the system’s angular momentum �̇� around the com changes. in the lipm in the 𝑥𝑧 plane, the system is assumed to have zero angular momentum 𝐻𝐶𝑜𝑀,𝑦 = 0, and the rate of change of angular momentum �̇�𝐶𝑜𝑀,𝑦 is also zero. this condition implies that the forces exerted by the system do not create any rotational effects around ibrahim altameemi al-khwarizmi engineering journal, vol. 20, no.3, p.p. 2035 (2024) 22 the com. furthermore, in the lipm, the height of the com is assumed to remain constant. the motion characteristics of the planar lipm in the forward-backward direction, as shown in figure 2 (a), can be mathematically represented as 𝑚�̈�𝐶𝑜𝑀 = 𝑚𝑔 𝑧0 (𝑥𝐶𝑜𝑀 − 𝑥𝐶𝑜𝑃) … (1) �̇�𝐶𝑜𝑃 = 𝑢 … (2) where 𝑥𝐶𝑜𝑀 is the com horizontal position at a constant height 𝑧0, 𝑚 is the system’s total mass, 𝑥𝐶𝑜𝑃 is the cop position, 𝑔 is the gravitational acceleration, and 𝑢 is the control input for the cop. as shown in figure 2 (a), to satisfy the assumption that (�̇�𝐶𝑜𝑀,𝑦 = 0), the ground reaction force (grf) must point from the cop in the direction of the com. fig. 2. simplified models (a) linear inverted pendulum model (lipm), (b) linear inverted pendulum plus flywheel model (lipfm). linear inverted pendulum plus flywheel model (lipfm): the torque generated around the com, which is equal to the rate of change of angular momentum, can have a substantial effect on push recovery. the torque measured is a consequence of the rotating motion of the upper body, which includes the torso and the arms. hence, in the simplified model depicted in figure 2 (b), a flywheel positioned on the com should be employed as an approximation for the upper body. the system’s behaviour in the sagittal plane can be mathematically represented as follows: 𝑚�̈�𝐶𝑜𝑀 = 𝑚𝑔 𝑧0 (𝑥𝐶𝑜𝑀 − 𝑥𝐶𝑜𝑃) − 𝜏𝑦 𝑧0 … (3) 𝐼𝑦 �̈�𝑦 = 𝜏𝑦 … (4) where 𝜏𝑦 is the torque generated by the flywheel about the com, �̈�𝑦 is the acceleration of the flywheel, and 𝐼𝑦 is the inertia of the flywheel. centroidal dynamic model: the com dynamic equation of bipedal robots can be formulated as [ 𝐴𝐶𝑜𝑀,1 𝐴𝐶𝑜𝑀,2 ] 𝐹𝐶𝑜𝑛𝑡𝑎𝑐𝑡 = 𝑏𝐶𝑜𝑀 … (5) where 𝐴𝐶𝑜𝑀,1 = [𝐼3×3 𝐼3×3 03×3 03×3] … (6) 𝐴𝐶𝑜𝑀,2 = [(𝑝𝑅 − 𝑐) (𝑝𝐿 − 𝑐) 𝐼3×3 𝐼3×3] … (7) 𝐹𝐶𝑜𝑛𝑡𝑎𝑐𝑡 = [ 𝐹𝑅 𝐹𝐿 𝑀𝑅 𝑀𝐿 ] … (8) 𝑏𝐶𝑜𝑀 = [ 𝑚(𝑔 + �̈�) �̇� ] … (9) 𝑝 is the position of the foot, 𝐹 is the foot contact force, 𝑀 is the foot contact moment, 𝐻 is the com angular momentum, and 𝑐 is the position of the com. the subscript 𝐿 represents the left foot, and 𝑅 represents the right foot [13] [14]. 2.2.2. whole-body dynamic model bipedal robots are floating base systems in which the robot’s base (torso or pelvis) is not fixed to the ground and is capable of moving flexibly [15]. the floating base dynamics must consider the base motion as a component of the overall system dynamics. the joint-space whole-body dynamics of floating-base bipedal robots can be described as follows: 𝑀(𝑞)�̈� + 𝑁(𝑞, �̇�) = 𝐵𝜏𝑞 + 𝐽(𝑞)𝑇𝐹𝑓 … (10) where 𝑞 ∈ 𝑅𝑛+6 denotes the generalised coordinates (𝑞 = [𝑞𝑏𝑎𝑠𝑒 , 𝑞𝑗𝑜𝑖𝑛𝑡𝑠]) and 𝑞𝑏𝑎𝑠𝑒 = [𝑥, 𝑦, 𝑧, ∅, 𝜃, 𝜑], which represent the position and orientation of the robot’s base. 𝑀(𝑞) ∈ 𝑅(𝑛+6)×(𝑛+6) is the rigid body dynamic inertial matrix, 𝑁(𝑞, �̇�) ∈ 𝑅𝑛+6 is the generalised force vector of all modelled forces including the coriolis force, centrifugal force and gravity, 𝜏𝑞 ∈ 𝑅𝑛 is the driving torque vector, 𝐵 = [0𝑛×6 𝐼𝑛×𝑛] is the select matrix, 𝐼𝑛×𝑛 is the 𝑛-dimensional identity matrix, 𝐽(𝑞) ∈ 𝑅𝑘×(𝑛+6) is the force jacobian matrix, 𝐹𝑓 ∈ 𝑅𝑘 is the foot contact force, and 𝑛 is the number of joints of the robot [14]. additional details on the derivations of floating-base dynamics can be found in [15]. 2.3. basic balance strategies human balance investigations show that people have several strategies for dealing with disturbances [16-17]. figure 3 shows three main strategies: ankle, hip and step. the ankle strategy limits hip and knee motion and uses ankle torque to move the com [18]. the ankle joint torque affects cop balancing. this approach works well for minor disturbances, and the lipm can simplify its analysis. the hip strategy is used for major ibrahim altameemi al-khwarizmi engineering journal, vol. 20, no.3, p.p. 2035 (2024) 23 external disturbances [19]. hip torque quickly creates a moment around the com, thus increasing ground reaction forces [20]. this assumption allows the lipfm to analyse this strategy. when the disturbance increases and the ankle and hip strategies fail, a necessary step must be taken to prevent tipping over. some studies [21,22] have integrated these three strategies to develop a more robust response to disturbances. fig. 3. three basic balancing strategies [23]. 3. push recovery control 3.1. push recovery control techniques for standing bipedal robots [24,25] demonstrate the modelling and application of ankle and hip strategies on a bipedal robot that is exposed to an unexpected pushing force while maintaining an upright standing position. a basic planar dynamical model in the sagittal plane represents both strategies. the bipedal robot is supposed to maintain balance by having a stationary support foot and vertical reaction forces that pass through the com. thus, the authors of [24,25] achieve balance by ensuring that the wrenches exerted on the support foot, which are caused by the movements of the links, are reduced to zero. in the hip strategy, the reaction null-space method is utilised to acquire all joint accelerations/velocities that are necessary to maintain balance. the experiments validate the robot’s ability to respond immediately, which is similar to that of a human. the study by [23] presents a proposed method for a bipedal robot to regain balance by utilising the knee joint. a virtual model control (vmc) system utilising a spring and damper is employed to achieve a compliant response for the ankle strategy. the reaction null-space method is employed to establish the correlation between the ankle and knee joints. the simulation findings demonstrate that the robot’s ability to maintain balance is enhanced when the ankle and knee joints are engaged, even in the face of significant external forces as opposed to relying solely on the ankle strategy when the knee joint is immobilised. model predictive control (mpc) has two types: simplified-model mpc and whole-body mpc. in the first type, simplified dynamical models are used in the mpc to predict the control sequences over a receding horizon into the future. although a simplified-model mpc can execute the desired tasks in real time at a high rate, it limits the capability of bipedal robots to behave naturally and precisely. hence, other researchers use whole-body mpc, which allows robots to perform tasks with high accuracy. the main drawback of the wholebody mpc is the optimisation problem, which is computationally expensive. in [26], a convex model hierarchy predictive control (mhpc) is developed to stabilise a bipedal robot called bruce in its normal upright position following a push. the mhpc employs the simplified model (centroidal dynamics) in the short term while relying on whole-body dynamics in the long term. this approach allows for the benefits of quick execution and precise actions. the optimisation problem is expressed as a quadratic program (qp) with two terms (the first term represents the operational space tasks, such as the upright posture of the body and the trajectory of the swing leg, while the second term aims to achieve the desired com position and momenta). experimental results show the ability of bruce to maintain balance and return to an upright posture in a natural and compliant manner after being pushed with a constant pushing force. [20] proposes a push recovery control system that utilises foot positioning. the robot is equipped with an attitude and heading reference system (ahrs) that monitors the com’s position and velocity changes in response to the push. the robot is represented mathematically as an inverted pendulum of constant length, and the length of the stride is calculated to counterbalance the kinetic energy increase that occurs upon impact. fig. 4. illustration of the convex mhpc framework [26]. ibrahim altameemi al-khwarizmi engineering journal, vol. 20, no.3, p.p. 2035 (2024) 24 the study by [27] introduces a balance controller that enables a humanoid to regain stability after experiencing significant disturbances while maintaining an upright stance. the study employs a combination of a linear quadratic regulator and computed torque control to determine the desired position of the cop. next, a method including integral control is suggested to regulate the position of the cop precisely. a practical hierarchical push recovery approach is introduced in [28]. the approach comprises lowlevel controllers that execute three push recovery processes, which focus on the ankle, hip and step. to select from these strategies, a high-level controller uses the reinforcement learning approach in stochastic policy gradients. the highlevel controller utilises sensory information and the present state of the low-level controllers to select and implement the most suitable strategy. the study by [29] introduces a model-driven learning approach that enables a humanoid robot to maintain balance by adjusting its step length. the study employs a basic central pattern generation system to generate a walking motion. this system takes the amplitude vector of the leg swing as an input and creates regular signals for the leg joints. during the moment of support exchange, the system measures the trunk inclination and its rate and simultaneously estimates the step length and trunk position. the balance controller utilises these two variables for training. to maintain balance, the authors of [29] combine the simple proportional controller of the pendulum cart model with footstep error to generate an appropriate adjustment of the step length. this modification is incorporated into the gradient function. next, the gradient function is employed to train the balance control function to determine the swing leg amplitude. [22] proposes a partition-aware controller for balanced basins. this controller is enhanced to incorporate the captured-stepping approach, which aims to reestablish balance. the balanced state boundaries in the ankle and hip strategy are actively utilised as explicit criteria for selecting among the ankle, hip and captured-stepping methods. thus, they provide the current estimated com state of the robot. at all times, the ankle subcontroller is active. simultaneously, the activation of the hip and captured-stepping subcontrollers occurs only when the estimated com state exits the balanced basins for the ankle and hip, respectively. this study formulates capturability by taking into account the wholebody system dynamics of a humanoid robot to establish suitable conditions for balance recovery steps. in [11], the ankle strategy is presented as a means of maintaining stability for a humanoid robot that experiences external pushing forces. the zmp/cop position can be regulated to zero by changing the reference joint position through a joint position pd controller. the simulation findings demonstrate that the simulated bipedal robot can counteract external shocks of up to 10 n, thus resulting in a reduction of oscillation by 60%. in [30], a push recovery control method is developed to determine when and where to take a step to prevent falling. a new term called capture point is defined, which is a location on the ground that the bipedal robot must move to maintain stability. to derive this point, the concept of orbital energy is applied to lipm. however, if lipfm is employed to represent the dynamics, multiple points can be calculated. in this case, a new term called capture region is defined. a capture region is a set of capture points that the robot can step on to preserve stability. simulation results demonstrate that a bipedal robot can maintain stability by taking a single step in response to a pushing force. the work [13] introduces push recoverymodel predictive control (pr-mpc) as an approach to generate complete-body step recovery movements following a significant disturbance. the objective of the pr-mpc is to achieve the stationary position of the com just above the centroid of the support polygon. a quadratic programming problem is formulated to determine control inputs that will subsequently be inserted into the discrete representation of the lipm to construct the trajectory of the com. low-gain pd joint tracking control is employed in combination with feedforward torques generated by dynamic balance force control (dbfc) for tracking desired trajectories. the findings demonstrate that the humanoid robot, known as sarcos, possesses the capability to regain stability and counteract disruptions through the execution of a single step. the virtual leg model depicted in figure 5 is introduced in [12]. this model is characterised by connecting a virtual link between two virtual revolute joints, which is precisely positioned between the left and right hip joints and left and right ankle joints in the frontal plane. in their study, the authors of [12] utilise a pd controller to counteract the external force and restore the robot to the upright posture. ibrahim altameemi al-khwarizmi engineering journal, vol. 20, no.3, p.p. 2035 (2024) 25 fig. 5. virtual leg model [12]. the author in [31] presents dbfc as a modelbased method for obtaining the required joint torques of the whole body. this computation is derived from the movement of the com and the forces encountered at the contact locations. the contact forces that govern the rate of change of linear and angular momenta are determined through a constrained optimisation problem. a unified model predictive control (mpc) system regulates the position of the capture point by adjusting the zmp and the cmp using ankle and hip techniques [32]. the zmp is utilised to regulate the capture point when it falls within the support polygon. the cmp is employed when the capture point is located outside of the support polygon. the study [33] introduces a novel control method to regulate the position of the com and the orientation of the trunk of a bipedal robot compliantly. the objective is to calculate the necessary torque exerted at the com to restore the body’s position despite external disturbances. next, the force distribution framework is employed to allocate the needed wrench at predetermined contact locations through a constrained optimisation problem, as shown in figure 6. fig. 6. proposed balancing controller in [33]. [34] presents an innovative technique for humanoid robots to recover from a push by using the rotational dynamics. the process begins by calculating the centroidal angular momentum (cam) reference in real time using the magnitude and direction of the pushing forces. then, a quadratic optimisation problem is developed, including the cam reference as an input. this problem aims to generate feasible whole-body motion by optimising the adjusted velocities, including the linear velocity of the com, the angular velocity of the hip and the translational and rotational velocities of the right and left foot. the final torque required for the robot’s desired motion is determined using the passivity-based wholebody controller provided in [35] in the last stage of the process. the experiments demonstrate the humanoid robots’ potential to maintain balance and prevent falling when standing on either one or two legs. table 1 presents a comparison of the investigated studies that examine standing stability. the comparison is based on three key factors: the dynamical model used, the push recovery technique employed and the sensors required. 3.2. push recovery control techniques for walking bipedal robots [36] introduces a push detector that relies on the com error. it also suggests two control strategies ibrahim altameemi al-khwarizmi engineering journal, vol. 20, no.3, p.p. 2035 (2024) 26 to deal with pushing forces that may arise while walking effectively. the initial control method is the hip and ankle strategy, which is effective only when a force is detected before the foot is lifted off the ground. this approach produces a rotational force at the hip joint to counteract the rotational motion caused by external forces. it generates significant rotational forces at the ankle joint to generate opposing forces. consequently, the robot would increase its step length to regain equilibrium. however, if the push is sensed during the leg’s swing phase, the knee approach is employed to flex the knee joint and slow down the movement of the upper trunk. the simulation results demonstrate the biped’s capability to regain stability after experiencing significant external forces while walking. [37] introduces a trajectory generation system, which includes a push recovery trajectory generator to deal with disturbances effectively. the walking trajectory generator utilises preview control to construct the planned com trajectory for regular walking. the authors of [37] enhance the generic walking trajectory by incorporating a push recovery trajectory generator that mimics human behaviour in the presence of disturbances, as shown in figure 7. to ensure stability in the case of a push, the trajectory of the swing leg is modified to mitigate the angular momentum generated by the push on the com. the robot’s upper body bends simultaneously to counterbalance the disturbance caused by human reactions to external pushes. a human-like motion control pipeline is shown in figure 8. [38] describes a push recovery control implemented via walking phase modification. it presents two controllers. the first is the normal walking pattern generator, which generates normal walking in the absence of pushing using lipm. the system executes the push recovery controller, which is the second controller, as soon as the push occurs, as illustrated in figure 9. acceleration (occurring when com velocity increases) and deceleration (occurring when com velocity decreases) are the two phases of this controller. the concept of orbital energy is utilised to decide whether the robot is experiencing an external push. the leg must promptly land to transition to the deceleration phase if the push occurs during the acceleration phase. this step is required to prevent the further acceleration of the com velocity and to calculate a new com position in a manner that minimises the orbital energy. the simulation outcomes demonstrate the efficacy of the research [38] regarding recovery from a push while walking. fig. 7. proposed push recovery trajectory generation in [37]. the implementation of a two-level dynamic walking controller on a real robot named bruce is demonstrated [39]. the divergent component of motion (dcm)-based high-level footstep planner is the initial controller that determines the position and duration of the upcoming steps. dcm is an enhancement to lipm that incorporates a dynamic reference trajectory for the com. this modification improves the stability and naturalness of the motion. the whole-body control is the lowlevel controller responsible for determining the joint torques needed to create planned foot contact. it also regulates other task-space behaviours, including com height, swing leg position and torso orientation. controllers for real-time applications utilise small-scale quadratic programming to guarantee optimality. the findings indicate that bruce can successfully recover by adjusting the position of each footstep and the duration of each step in the subsequent few movements. ibrahim altameemi al-khwarizmi engineering journal, vol. 20, no.3, p.p. 2035 (2024) 27 fig. 8. human-like motion control pipeline [37]. fig. 9. push recovery control system [38]. the work [40] introduces a push recovery controller designed to improve the walking capabilities of bipedal robots. the k-means algorithm is modified in this study to identify the zmp trajectories as either safe or not safe. after selecting the safe zmp trajectory, inverse ibrahim altameemi al-khwarizmi engineering journal, vol. 20, no.3, p.p. 2035 (2024) 28 kinematics (ik) is used to determine the joint angles necessary to track the trajectory. [41] presents a control technique for restoring orientational force using angular momentum control. this restoration is achieved by utilising the virtual mass-ellipsoid inverted pendulum model shown in figure 10, which was initially presented in [42]. a novel objective function is introduced for push recovery during walking, which utilises enhanced intrinsically model predictive control (is-mpc). the results demonstrate the robot’s ability to maintain stability when walking over rough terrain. fig. 10. virtual-mass-ellipsoid inverted pendulum model [41]. the study [43] presents a controller designed to handle a sudden and severe push that happens when a humanoid robot is walking. the robot exhibits typical walking behaviour. when a push is recognised based on the linear velocity of its body, the push recovery control mechanism is activated. the algorithm initially computes the necessary steps for recovery and subsequently uses the preview control method described in [44] to construct the trajectory of the com. to mimic the deceleration phase of the lipm (which involves a loss of energy), the authors of [44] adjust the zmp reference by shifting it a certain distance behind the foot. ik is derived to compute the joint variables required to make the robot follow the updated zmp reference. the aim of [45] is to develop a technique for producing locomotion patterns for humanoid robots that are simultaneously dynamic (capable of adjusting to changing circumstances) and versatile (capable of dealing with diverse scenarios). the authors of [45] suggest employing a combination of two models: the 3d actuated spring-loaded inverted pendulum (3d-aslip) to simulate the robot’s physical dynamics and the hybrid linear inverted pendulum (hlip) as a control mechanism to assist in producing stepping patterns. the stepping controller based on hlip is designed to disturb the periodic walking motion of a 3d-aslip to provide dynamic and versatile walking, as shown in figure 11. fig. 11. overview of the approach presented in [45]. the approach presented in [46] can be seen as an expansion of stepping controllers in [47] [46] [48] and [49], which use the step-to-step (s2s) dynamics approximation to strategise footsteps for the stabilisation of bipedal walking. the process begins by implementing the hybrid-lip stepping technique described in [47] to produce a sufficient amount of waking data for learning. next, the discrete horizontal com state and the actual step size in the s2s dynamics are obtained. the stepping controllers, based on system-level synthesis (sls), are designed using the learned dynamics of the s2s process. these controllers consider bounded push disturbances and kinematic constraints. the study by [50] proposes a method for detecting pushes based on changes in the angle and angular velocity of the robot’s torso. it also suggests a strategy for avoiding falls by adjusting the positioning of the robot’s feet. the rescue step size is determined by calculating the difference between the initial and final kinetic energy of the ibrahim altameemi al-khwarizmi engineering journal, vol. 20, no.3, p.p. 2035 (2024) 29 lipm, which takes into account that the final com will be located on the line connecting the original com and the capture point. the work [51] presents a closed-loop feedback control approach that utilises an accelerometer and gyroscope to enable a cost-effective humanoid robot to maintain balance and recover from external forces while walking. the control method consists of three stages. in the first stage, falling is detected and classified into three categories (hard push, medium push and light push) using gyroscope and accelerometer sensors. in the second stage, the appropriate response (cop balancing, cmp balancing and step-out strategy) is selected based on the strength and direction of the push. during stage 3, nine walking parameters, such as step length, step pace, hip-pitch position and ankle-pitch position, are modified according to the magnitude and direction of the applied pushing forces. in [1], a method is proposed to enhance the dynamic stability of humanoid robots. the nominal footstep position and time are inputs to the dcm planner, which are generated by the foot position planner. with the implementation of the dcm planner, the nominal dcm trajectory and foot position are generated. using nominal values of foot and dcm trajectories in conjunction with observations of the actual dcm (desired com), the authors propose a stepwise adaptor. this integration allows for the evaluation of adapted foot trajectories, footstep position and time. to compute the required torques needed to achieve these updated parameters, a whole-body qp control is implemented. to generate walking trajectories, the com trajectories must remain aligned with the zmp trajectory and not deviate from it. nevertheless, not all zmp trajectories can be executed without the com diverging. in [52], a novel method for generating online walking trajectories is introduced. this method incorporates nondivergence constraints for zmp-com. this approach allows for the integration of walking direction and speed adjustment, as well as recovery from unknown external forces, in a unified manner. [53] proposes a mathematical model called the virtual force linear inverted pendulum model (vflipm), which causes a bipedal robot to change its gait pattern according to external disturbances. a natural zmp reference is utilised to generate the dynamic gait pattern. once the push is detected using the zmp threshold, a fuzzy controller is developed to modify the gait pattern and vflipm parameters (lean angle, stride length and virtual mass of vflipm) based on the impact. table 2 presents a comparison of the investigated studies that specifically examine stability during walking. the walking pattern generation and push recovery strategy are emphasised for each study in addition to the dynamical models and sensors employed. table 1 comparison of push recovery control techniques for standing bipedal robots. reference dynamic model control method implementation platform sensor usage [24] [25] two-link planar robot vmc with null-space method (ankle and hip strategy) real humanoid (hoap-2) joint encoders [23] two-link planar robot vmc with null-space method (ankle and knee strategy) biped (simulation) joint encoders [30] lipm and lipfm step position control based on orbital energy concept (step strategy) two-link robot (simulation) [26] whole-body dynamics for short horizon and centroidal dynamics for long horizon model hierarchy predictive control (mhpc) (wholebody motion strategy) real biped (bruce) imu and contact foot sensors [20] lipm foot placement control using kinetic reduction (step strategy) biped (simulation) ahrs to measure angle and angular velocity [27] two-link planar robot integral control of cop position (hip strategy) biped (simulation) [28] lipm high-level control uses reinforcement learning to select among (ankle, hip real humanoid (darwin-hp) imu and joint encoders ibrahim altameemi al-khwarizmi engineering journal, vol. 20, no.3, p.p. 2035 (2024) 30 and step strategies) [29] simple pendulum cart model step position control using model-driven learning approach (step strategy) real humanoid (copedo) joint encoders [21] [22] centroidal dynamics whole body capturability (ankle, hip and step strategies) real humanoid (darwin-op) joint encoders [13] lipm and centroidal dynamics step position control using push recovery-mpc (prmpc) (step strategy) real humanoid (sarcos) force sensors [12] lipm com position control using pd controller (ankle and hip strategy) nao humanoid (simulation) joint encoders [32] lipfm capture point control using mpc (ankle and hip strategy) surena iii humanoid (simulation) [11] lipm zmp position control using pd controller (ankle strategy) biped (simulation) foot force sensors and joint encoders [31] centroidal dynamics dynamics balance force control (dbfc) (step strategy) real humanoid (sarcos) imu and foot force sensors [33] centroidal dynamics com position and trunk orientation control using contact force optimisation (whole-body motion strategy) real biped (dlrbiped) joint torques sensors [34] whole-body dynamic model whole-body balance control-based on centroidal angular momentum (cam) (whole-body motion) real humanoid robot (toro) imu, joint encoders and force sensor at the stick to measure the pushing force table 2 comparison of push recovery control techniques for walking bipedal robots. reference dynamic model control method implementation platform sense usage [36] lipm for normal walking step length control using ankle and hip strategy for double support phase and trunk velocity control using knee strategy for swing phase 21 dof biped (simulation) foot force sensor and imu [37] lipm for normal walking com trajectory generation with preview control for normal walking and push recovery trajectory generator modifies swing leg trajectory real biped imu and force/torque sensors [14] whole-body dynamics optimal ground reaction forces biped (simulation) imu and foot force sensors [38] lipm walking phase modification (transition between acceleration and deceleration phases) biped (simulation) accelerometer, body inclination sensor and foot force sensors [39] lipm for footstep planner and wholebody dynamics for whole body control two-level controllers (divergent component of motion-based high level footstep planner and low-level whole-body control to compute the joint torques) real biped (bruce) imu, joint encoders and force sensors [40] lipm feasible and stable zmp trajectory based on the k-mean algorithm. simulation body sensor based on human capture device (hcmd) [41] virtual mass ellipsoid intrinsically model predictive humanoid hrp4 ibrahim altameemi al-khwarizmi engineering journal, vol. 20, no.3, p.p. 2035 (2024) 31 inverted pendulum model control (is-mpc) for angular momentum control (simulation) [43] lipm preview control for normal walking and phase change for push recovery humanoid (simulation) accelerometer sensor [45] 3d actuated springloaded inverted pendulum (3d-aslip) stepping controller based on hybrid linear inverted pendulum model atlas humanoid (simulation) imu and joint encoders [46] hybrid linear inverted pendulum model step-to-step based stepping controller real biped (cassie) imu and joint encoders [50] lipm foot placement modification based on kinetic energy error of the upper body small scale humanoid (simulation) ahrs and foot force sensors [51] lipm for cop balancing and lipfm for cmp balancing cop balancing, cmp balancing and step strategy real humanoid (polaris) imu [1] lipm footstep position and time based on divergent component of motion planner humanoid (icub) (simulation) joint and body encoders [52] lipm online walking trajectories with non-divergence constraints for zmp-com real biped (hrp3l-jsk) 6-axis force sensor, accelerometer and fiber optic gyroscope (fog) [53] virtual force lipm (vflipm) to change the zmp and com to eliminate disturbances from environment a fuzzy dynamic gait pattern generator real robot (david junior ii) eight pressure sensors and imu 4. conclusion this study conducted a thorough examination of the innovative strategies and methodologies used to ensure the stability of bipedal robots in the presence of external disturbances. this work began by categorising previous studies into two categories: those that apply to standing robots and those that achieve stability while walking. subsequently, it systemically analysed and compared current methods, which focused on three key aspects: the dynamic model, sensor integration and push recovery control techniques. researchers in this field would benefit from this systematic classification by efficiently comparing and understanding previous studies as well as identifying research gaps that require future attention. numerous studies have focused on joint control strategies in the context of standing, which requires the activation of specific joints (e.g., the ankle, knee, or hip) to maintain balance in the presence of external pushing forces. when implementing joint control strategies, researchers frequently use simplified dynamical models, such as lipm and lipfm, to simulate the robot’s behaviour. however, these simplified models fail to account for certain body parts, such as the arms and the head, which leads to unnatural responses. consequently, previous research has attempted to generate whole-body motion to recover a push using a variety of techniques, including momentum-based balance control. as the level of disturbance increases, the robot must step to maintain stability. the capture point, which is based on the orbital energy concept, is the most systematic and efficient method in the literature for determining the step position (step strategy). walking pattern generation, push detection and push recovery control are essential elements for push recovery control during walking. the zmpbased approach consistently generates a walking pattern that maintains the zmp within the support polygon, thereby promoting stable walking. the literature suggests various approaches to detect exerted pushing forces, such as measuring the difference in the com trajectory or analysing the kinetic energy of the robot’s body. following a push detection, different push control systems use either reactive or predictive controllers to modify the robot’s posture and adjust the position of its footsteps, as demonstrated in previous research. despite these advancements, some obstacles still need to be addressed: 1) current methods often struggle to cope with unpredictable dynamic environments while also preserving real-time adaptation. ibrahim altameemi al-khwarizmi engineering journal, vol. 20, no.3, p.p. 2035 (2024) 32 2) current balance techniques exhibit promise in enhancing stability but with the drawback of increased energy use. 3) the dynamics of bipedal robots are complex and nonlinear, which results in increased computational requirements and latency issues. in the future, researchers should focus on combining sensory feedback methods with machine learning algorithms to make balance control systems that are adaptable and can quickly learn from and react to different disturbances in real time. previous studies have demonstrated the effectiveness of current methods in maintaining balance in static and dynamic situations. however, the high energy consumption associated with their use is a significant drawback. hence, future research must prioritise the development of control algorithms that effectively balance stability and energy efficiency. one possible way to enable bipedal robots to anticipate and respond to disruptions while minimising energy usage is to use predictive control algorithms that replicate humans’ natural reflexes. several research areas can be improved to accommodate the complexity of bipedal robot dynamics. the development of hybrid control methods that incorporate modelbased and data-driven approaches can significantly simplify the dynamics issue. moreover, using hierarchical control architectures, which break the balance control problem down 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[53] l.-f. wu and l. tzuu-hseng s., "fuzzy dynamic gait pattern generation for real-time push recovery control of a teen-sized humanoid robot," ieee access, vol. 8, pp. 36441-36453, 2020. this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 19, no. 1, march, (2023) p. p. 3656 yearly energy, exergy, and environmental (3e) analyses of a photovoltaic thermal moduleand solar thermal collector in series sameer teref azeez al-aridhee* mohammad moghiman** *,**department of mechanical engineering/ ferdowsi university of mashhad/ mashhad/ iran **email: eng.sameer3@gmail.com ***email: moghiman@um.ac.ir (3202 january 29 2022; accepted november 25received ) https://doi.org/10.22153/kej.2023.01.001 abstract the annual performance of a hybrid system of a flat plate photovoltaic thermal system and a solar thermal collector (pvt/st) is numerically analyzed from the energy, exergy, and environmental (co2 reduction) viewpoints. this system can produce electricity and thermal power simultaneously, with higher thermal power and exergy compared to conventional photovoltaic thermal systems. for this purpose, a 3d transient numerical model is developed for investigating the system's performance in four main steps: (1) investigating the effects of the mass flow rate of the working fluid (20 to 50 kg/h) on the temperature behavior and thermodynamic performance of the system, (2) studying the impacts of using glass covers on the different parts of the system, (3) evaluating the annual energy and exergy analyses of the system under mashhad weather conditions, and (4) examining the co2 reduction by using the proposed system. the results show that for the (glazed) pvt and (glazed) st systems, increasing the mass flow rate of the working fluid from 20 to 50 kg/h results in 22% and 1.5% improvements in both thermal and electrical power, respectively. however, the thermal exergy of the system decreases by 40.1%. furthermore, the (glazed) pvt/(glazed) st systems generate approximately 86% and 264% more thermal power and energy than the pvt/st systems, respectively. using a (glazed) pvt/(glazed) st system with a working fluid’s mass flow rate of 50 kg/h results in maximum thermal and electrical efficiencies of 40.7% and 16.22%, respectively. according to the annual analysis, the highest average thermal and electrical power, equal to approximately 338.3 and 24 w, respectively, is produced in august. the amount of co2 reduction increases by increasing the mass flow rate and using a glass cover. the pvt/(glazed)st system has the potential to reduce co2 emissions by 426.3 kg per year. keywords: photovoltaic thermal system, solar thermal collector, environmental analysis, energy and exergy analyses, co2 reduction. 1. introduction because of the world's fast population expansion and remarkable industrial progress, energy demand is significantly rising. moreover, the traditional energy sources, fossil fuels, are responsible for today's global warming, air and water pollution, wildlife harm, etc. a prospective replacement for these energy sources are renewable energy sources such as wind, solar, and geothermal. solar energy has received further attention among the various kinds of renewable energy because it is limitless and widely available [1]. in the last two decades, two main solar systems have been introduced for converting solar irradiation into heat and electricity for use in different residential and industrial applications. photovoltaic panels can generate electrical power, while solar thermal (st) collectors convert the received solar irradiation into thermal power. only a small amount of the sun's radiation can be converted by photovoltaic cells into electricity; the mailto:eng.sameer3@gmail.com https://doi.org/10.22153/kej.2023.01.001 sameer teref azeez al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 3656 (2023) 37 remainder only raises the temperature of the photovoltaic cells, which reduces their electrical performance and shortens their lifespan [2]. therefore, photovoltaic thermal (pvt) modules are used to solve the mentioned issues and recover the additional energy absorbed by photovoltaic cells [3]. in these systems, an st collector is attached beneath the photovoltaic panel, where working fluid (wf) passes through the tubes/ channels, resulting in a reduction in the temperature of the photovoltaic cells, an increase in the cells' efficiency, and the generation of thermal power [4]. nevertheless, the frequent deployment usage of pvts has significant restrictions due to some issues, namely, low wf outlet temperature, low thermal power, and exergy [5]. to tackle these problems and improve the performance of these systems, different enhancement methods are applied. as an example, some researchers have investigated the effects of adding nanofluids to wf [6], using turbulators through wf [7], employing phase change materials [8], a combination of these methods [1], and applying concentrators [9]. it should be mentioned that each improvement technique has its drawbacks. for example, nanofluids suffer from low improvements in low-volume fractions and possible settling and clogging in high-volume fractions [10]. furthermore, the leakage problem and decrease in wf temperature once pcms are used, as well as the high total and maintenance costs of concentrating photovoltaic thermal energy due to the complexity of the design, are issues with the mentioned methods [11]. because pvts have lower wf outlet temperatures, thermal powers, and energies than sts, they are not used in hightemperature applications. recently, to resolve these problems, a hybrid system of pvt and st (hybrid pvt/st), connecting these two systems in series, has been introduced. in this system, the wf passes through the pvt system and then enters the st section to increase the temperature to a suitable level for use in applications with a high required temperature. ma et al. [12] introduced the hybrid pvt/st system and numerically evaluated the performance of the system using a 2d model. their investigations were conducted under the shanghai, china, weather, where the lowest and highest amounts of electrical power were achieved in november and july, equal to 18.20 and 35.8 kwh, respectively. according to the annual analysis, the system could produce around 2096.51 and 298.50 kwh of thermal and electrical power, respectively. li et al. [5] numerically studied the hybrid pvt/st performance from energy and exergy viewpoints. they applied a glass cover on top of two sections to investigate the effects of it on the system's performance. the 2d numerical model results illustrated that using the glass cover could improve thermal power to a maximum of 4.10 kwh. moreover, using a glass cover decreased the electrical efficiency of cells due to the increase in cell temperature. han et al. [13] numerically compared the performance of two different systems, (1) a photovoltaic panel and st collector that worked separately (the first system only produces electricity and the next one provides thermal power); and (2) a hybrid pvt/st system. they conducted their simulations under a fixed heat flux and ambient temperature. they revealed that the hybrid pvt/st system performed better under the higher solar heat flux and ambient temperature. the performance of four solar systems, including st, photovoltaic panels, pvt, and hybrid pvt/st, was studied by kazemian et al. [14]. they developed a 3d numerical model and conducted their investigation under specific daytime weather conditions in july in shanghai, china. they demonstrated that the mass flow rate was the main determinant of the system's thermal and electrical output, after solar irradiation and wf input temperature. the performance of a hybrid pvt/st system with and without glass cover under the weather conditions of chennai, india, was studied by chandan et al. [15]. using the glazed hybrid pvt/st system increased the outlet temperature of the wf by 2-3 °c compared to the glazed pvt. furthermore, the glazed hybrid pvt/st system generated 23% less electrical power than the unglazed one. growing greenhouse gas emissions are one of the world's primary issues, resulting in significant environmental degradation. due to the significance of carbon dioxide (co2) management in the modern world, it is essential to investigate the environmental effects of clean energy systems such as pvt/st modules. although some environmental analysis has been undertaken on pvt systems, such as that of rajoria et al. [16], hassani et al. [17], and cetina-quiñones et al. [18], no research has been conducted on the hybrid pvt/st system. according to the literature, limited studies have been conducted to investigate the performance of the hybrid pvt/st system. only two studies investigated the annual performance of the pvt/st system by only focusing on the energy viewpoint. therefore, the annual performance of the system from an exergy viewpoint has not been investigated yet. moreover, there is no study on the sameer teref azeez al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 3656 (2023) 38 environmental aspect of using hybrid pvt/st systems. consequently, considering both the first and second laws of thermodynamics in the analyses, the main objectives of this study can be summarized as follows:  studying how the wf mass flow rate in the range of 20–50 kg/h affects the temperature behavior and thermodynamic performance of the (glazed)pvt/(glazed)st system.  evaluating the effects of glass cover on the system by defining various scenarios such as (glazed) pvt/(glazed) st, pvt/(glazed) st, and (glazed) pvt/st.  analyzing the performance of the pvt/(glazed)st system in an entire year from both energy and exergy standpoints.  examining the environmental effects of mass flow rate and glass cover on the pvt/(glazed)st system, including the reduction in co2 pollutants and the annual reduction in co2, note that all the simulations are conducted under the weather conditions of mashhad, iran. 2. numerical modeling 2.1 physical model as indicated in fig. 1, the hybrid pvt/st system is comprised of two main sections: (1) a photovoltaic thermal module, and (2) a solar collector system. the working fluid (wf) at the ambient temperature enters the pvt system and absorbs heat from the pv cells, resulting in a reduction in the pv cells' temperature and an increase in the wf outlet temperature. the heated wf, by passing through the connection tubes, enters the second section, the st system, to increase the outlet temperature to the desired level. fig. 1 also displays the different layers of the two sections. the pvt module includes a glass cover, pv cells with two layers of ethylene-vinyl acetate (eva), tedlar, an absorber plate, tubes containing wf, and insulation. moreover, the solar collector includes a glass cover, an absorber plate, tubes containing wf, and insulation. it should be mentioned that the effect of using a glass cover on top of each part is studied, while in the figure, the (glazed) st and pvt (unglazed) are the only ones shown. the air gap and glass cover prevent the transfer of heat to the surrounding environment. in numerical modeling, to reduce the cost and time of software-based calculations, only one tube is considered. the accuracy of this assumption has been proven in refs. [4, 19]. table 1 lists the geometrical dimensions, whereas table 2 lists the thermophysical and radiative parameters associated with the system. water has been used as a wf in the present study. fig. 1 (a) schematics of the pvt/st system along with cross-sectional views of (b) unglazed photovoltaic thermal (pvt) system and (c) glazed solar thermal (st) collector with their various layers. high-temperature water unglazed photovoltaic thermal (pvt) system glass glazed solar thermal (st) collector electricity pv cells eva insulation working fluidworking fluid tube absorbereva tedlar air gap (a) (b) (c) sameer teref azeez al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 3656 (2023) 39 table 1, dimensions of the pvt/st system [4, 12]. system component dimensions (m) the glass cover of the pvt and st 2×0.1×0.0032 the absorber of the pvt and st 2×0.1×0.004 air gap 2×0.1×0.025 eva 2×0.1×0.0005 photovoltaic cells 2×0.1×0.0003 tedlar 2×0.1×0.0001 tube length of each part 2 tube outlet diameter 0.1 thickness of the tube 0.01 table 2, thermophysical and radiation properties of the different elements [4, 12]. system component density (kg/m3) conductivity (w/m.k) specific heat (j/kg.k) transmittance absorptance glass cover 2200 0.76 830 0.95 0.02 eva 960 0.35 2090 1 0 photovoltaic cells 2330 148 700 0 0.92 tedlar 1200 0.2 1250 absorber plates and tubes 8960 401.00 385 0 0.95 2.2 assumptions in this research, assumptions have been considered to solve the equations and decrease some complexity in modeling. the laminar flow regime is considered due to the reynolds number being less than 2300 and the maximum mass flow rate of 50 l/h considered in this study [20]. the anti-reflection coating layer for the pv cells has a very small thickness (0.0001 mm), so it is omitted in this numerical study. moreover, the contact resistance between the layers is assumed to be negligible. the thermal properties of all materials are constant and do not change with temperature changes. to simulate the input radiation, it is assumed that the radiation is uniform and perpendicular to the surfaces of the two parts of the system. 2.3 governing equations for the solid parts (subscript “s”) of both pvt and st components, the conduction heat transfer is as follows [14]: (𝜌𝑠𝑐𝑝,𝑠) 𝜕𝑇𝑠 𝜕𝑡 = ∇. (𝑘𝑠∇𝑇𝑠) + 𝐸𝑠𝑢𝑛 𝑒𝑓𝑓,𝑃𝑉 𝑜𝑟 𝑎𝑏𝑠 ′′ − 𝐸𝑒𝑙 ′′ …(1) t_ ،ρ_ ،c_p and k_ are the temperature, density, specific heat, and thermal conductivity, respectively. moreover, e_(sun eff,pv or abs)^'' and 〖e''〗_el indicate the effective energy absorbed by pv cells and absorber plate and the electric power produced in the pv cells, respectively. it is clear that the second term is zero for all other layers. these source terms can be calculated by the following relations [4, 12]: 𝐸𝑠𝑢𝑛 𝑒𝑓𝑓,𝑃𝑉 𝑜𝑟 𝑎𝑏𝑠 ′′ = 𝜏𝑔𝑙𝑎𝑠𝑠𝛼𝑃𝑉 𝑜𝑟 𝑎𝑏𝑠𝐼𝑠𝑢𝑛 …(2) eel ′′ = esun eff,pv ′′ ηr[1 − 0.0045(tcell − 298.15)] …(3) using user-defined function (udf) codes, these source terms are applied to the numerical simulation. in these equations, τ_glass is the transmission coefficient of the glass, α_(pv or abs) is the absorptivity coefficient of the pv cells or absorber plate, i_sun is the solar irradiation, and η_r is the reference efficiency of the pv cell, which is equal to 0.173. the continuity, momentum, and energy equations for fluid (wf and air) are given as follows [21]: ∇⃗⃗ . (ρ𝑓�⃗� 𝑓) = 0 …(4) ∇⃗⃗ . (ρ𝑓�⃗� 𝑓�⃗� 𝑓) = −∇⃗⃗ p + ∇⃗⃗ τ1 + ρ𝑓g⃗ …(5) ∇⃗⃗ . (ρ𝑓𝑐𝑝,𝑓𝑇𝑓�⃗� 𝑓) = ∇⃗⃗ . (𝑘𝑓 ∇⃗⃗ 𝑇𝑓) …(6) v _fand p present fluid velocity and pressure, respectively, and subscript “f” stands for both fluids of wf in the tube and air inside the gap. sameer teref azeez al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 3656 (2023) 40 2.4 boundary conditions the boundary conditions of the inlet and outlet are set to mass flow inlet and pressure outlet, respectively. moreover, the adiabatic walls are applied to the lateral sides, tube, and absorber plates of both components of the system. to calculate the amounts of radiation and convection heat transfer to the environment, the convection heat transfer coefficient and the sky temperature are calculated by [22, 23]: 𝑇𝑠𝑘𝑦 = 0.0552𝑇𝑎𝑚𝑏 1.5 (1)... ℎ𝑤𝑖𝑛𝑑 = { 5.7 + 3.8𝑉𝑤𝑖𝑛𝑑 𝑖𝑓 𝑉𝑤𝑖𝑛𝑑 < 5 𝑚 𝑠 6.47 + 𝑉𝑤𝑖𝑛𝑑 0.78 𝑖𝑓 𝑉𝑤𝑖𝑛𝑑 ≥ 5 𝑚 𝑠 (2)... 𝑉𝑤𝑖𝑛𝑑 and 𝑇𝑎𝑚𝑏 are wind velocity and ambient temperature, respectively. 2.5 performance evaluation method the thermal power of the system is calculated by [14]: �̇�𝑡ℎ = �̇�𝑓𝑐𝑝,𝑓(𝑇𝑓,𝑜𝑢𝑡 − 𝑇𝑓,𝑖𝑛) …(9) (3) where �̇�𝑓, 𝑇𝑓,𝑜𝑢𝑡 , and 𝑇𝑓,𝑖𝑛 are mass flow rate, and wf temperatures at the inlet and outlet, respectively. to calculate thermal and electrical efficiencies, the following equations can be used, respectively [5]: 𝜂𝑡ℎ = �̇�𝑡ℎ (𝜏𝑔𝑙𝑎𝑠𝑠𝛼𝑃𝑉 𝐴𝑝𝑣𝐼𝑠𝑢𝑛) + (𝜏𝑔𝑙𝑎𝑠𝑠𝛼𝑎𝑏𝑠 𝐴𝑎𝑏𝑠𝐼𝑠𝑢𝑛) …(10) (4) 𝜂𝑒𝑙 = 𝐸𝑒𝑙 ′′ 𝜏𝑔𝑙𝑎𝑠𝑠𝛼𝑃𝑉 𝐼𝑠𝑢𝑛 …(11) (5) where, 𝐴𝑝𝑣 and 𝐴𝑎𝑏𝑠 are the surface area of pv cells and absorber plate, respectively. using the following equations, the rate of electrical and thermal exergy can be calculated [24]: 𝐸�̇�𝑒𝑙 = 𝐸𝑒𝑙 ′′ × 𝐴𝑝𝑣 (6)... 𝐸�̇�𝑡ℎ = �̇�𝑓𝑐𝑝.𝑓 ((𝑇𝑓.𝑜𝑢𝑡 − 𝑇𝑓.𝑖𝑛) − 𝑇𝑎𝑚𝑏𝑙𝑛( 𝑇𝑓.𝑜𝑢𝑡 𝑇𝑓.𝑖𝑛 )) (7)... 2.6 environmental analysis: co2 reduction the usage of renewable energy minimizes carbon dioxide (co2) emissions caused by the burning of fossil fuels. therefore, the amount of this reduction by using the proposed system is studied. it should be noted that the amount of carbon dioxide reduction can be obtained from the two points of view of energy and exergy, whose general relations are the same. the amount of carbon dioxide reduction (kg per month/year) can be calculated as follows [16]: ∅𝐶𝑂2 = 𝛽𝐶𝑂2 × �̇�𝑒𝑞,𝑡𝑜𝑡𝑎𝑙 (8)... �̇�𝑒𝑞,𝑡𝑜𝑡𝑎𝑙 is the total amount of energy produced by the system, including electrical and thermal power by taking into account the power plant efficiency of 38% as follows [16]: �̇�𝑒𝑞,𝑡𝑜𝑡𝑎𝑙 = (𝐸𝑒𝑙 ̇ + 0.38 × �̇�𝑡ℎ) × 𝑛/1000 (9)... in this equation, n represents the total monthly operating hours for the city of mashhad, as depicted in fig. 2. the quantity of n is determined based on the number of sunny days in a month (using the data provided by [25]) and operating hours of the system, which is considered 8 hours per day in this study. in eq. (14), 𝛽𝐶𝑂2 is the amount of co2 production per coal consumption to produce a kw of useful power, which is usually considered equal to 2 [16]. sameer teref azeez al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 3656 (2023) 41 fig. 2. the total number of working hours per month in mashhad [25]. 2.7 numerical simulation procedure using ansys fluent version 18.2, a 3d transient numerical model is developed for evaluating the performance of the pvt/st system. the pressure-based solver is employed for the laminar regime of wf, and the simple method is used to couple pressure and velocity. the secondorder upwind is used for discretizing different terms in all governing equations, while the peresto scheme is employed for the pressure [26, 27]. furthermore, in solving continuity, momentum, and energy equations, convergence criteria of 10-6, 10-6, and 10-8 are considered, respectively. 2.8 grid and time-step independence study in this section, two important parameters affecting the numerical solution, including the number of grids and time step, have been investigated. the geometry of the pvt/st is generated in solidworks software, and then a structural mesh is provided for the computational domain using ansys meshing software. fig. 3(a) illustrates the structural grid system used for the pvt part of the system. fig. 3(b) and (c) show the results of grid and time-step independence when two parameters are considered: wf outlet temperature and thermal power. four grids of 605000, 1270000, 2650000, and 5150000 are considered. comparing the data for the 605000 and 1270000 grids with the 5150000 grids reveals errors of approximately 10% and 6%, respectively. nonetheless, the error for 2650000 grids is approximately 1.5% compared to the case with 5150000 grids. as a result, the grid system with 2650000 grids is chosen for the remainder of the research. finally, at the selected grid system, the effects of applying different time steps of 17, 35, 70, and 140 s on the two considered parameters are compared, as shown in fig. 3(c). regarding both calculation speed and accuracy of results, a time step of 70 s was chosen for this study. 0 50 100 150 200 250 april may jun july augest september october november december january february march hours of working in a month (h) sameer teref azeez al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 3656 (2023) 42 fig. 3 (a) sample of the structural grid system used for the pvt part of the system along with investigating the independence of (b) grid number and (c) time-step. 3. model validation to ensure that the results of the numerical study are accurate, the outputs of the present modeling for a pvt/st system are compared with the experimental data provided by chandan et al. [15]. their pvt section consisted of 70 cells with an aluminum collector with 12 straight tubes (with an outer diameter and thickness of 16 and 0.5 mm, respectively). the st section was made of copper with nine straight tubes (with an outer diameter and thickness of 12 and 0.5 mm, respectively). the length and width of both sections were equal—2 and 1 meters, respectively. the bottom surfaces of both systems were insulated by glass wool with a thickness of 50 mm. other geometrical and thermophysical properties of layers are available in ref. [15]. fig. 4 illustrates the thermal and electrical power generated by the st and pvt sections of the system, calculated by the numerical model and presented by suresh et al. [15]. the experiments were conducted under the weather conditions of chennai, india, at a flow rate of 30 l/h. according to the figure, the average errors for electric and thermal power are about 2.5% and 2.3%, respectively, which shows that the experimental and numerical results are in good agreement. fig. 4 comparing the thermal and electrical power calculated by using the numerical model with the experimental data reported by suresh et al. [15]. 125 130 135 140 145 150 155 305.55 305.6 305.65 305.7 305.75 305.8 305.85 305.9 305.95 306 605000 1270000 2650000 5150000 t h er m al p o w er ( w ) w f o u tl et t em p er at u re ( k ) mesh number outlet temperature pv surface temperature 143 144 145 146 147 148 149 305.84 305.86 305.88 305.9 305.92 305.94 305.96 17 35 70 140 t h er m al p o w er ( w ) w f o u tl et t em p er at u re ( k ) time step (s) outlet temperature pv surface temperature (b)(c) (a) 0 100 200 300 400 500 0 100 200 300 400 500 600 700 800 9 10 11 12 13 14 15 16 e le c tr ic a l p o w e r (w ) t h e rm a l p o w e r o f s t p a rt ( w ) time (h) experimental results thermal numerical results thermal experimental results electrical numerical results electrical sameer teref azeez al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 3656 (2023) 43 4. results and discussion this study is presented in different sections. first, the effects of mass flow rate on the performance of the system have been explored. next, the impacts of the glass cover on the different parts of the system are discussed. these sections are carried out under the august weather conditions of mashhad, iran. then, the yearly performance of the system is presented for both energy and exergy. finally, an environmental analysis is presented, considering the effects of flow rate and glass cover. the variations of the average hourly solar irradiation and ambient temperature in a whole year in mashhad, iran, along with the average wind speed for each month, are plotted in fig. 5 [28]. note that the weather conditions vary during the day; therefore, by utilizing udf, these conditions have been applied in the software. fig. 5. average hourly variations of (a) solar irradiation, (b) ambient temperature in a whole year in mashhad, and (c) average wind speed for each month [28]. 0 100 200 300 400 500 600 700 800 900 1000 7 9 11 13 15 17 s o la r i r r a d ia ti o n ( w /m 2 ) time (h) april may jun july augest september 270 275 280 285 290 295 300 305 310 7 9 11 13 15 17 a m b ie n t te m p e r a tu r e ( k ) time (h) april may jun july augest september 0 100 200 300 400 500 600 700 800 900 1000 7 9 11 13 15 17 s o la r i r r a d ia ti o n ( w /m 2 ) time (h) october november december january february march 270 275 280 285 290 295 300 305 310 7 9 11 13 15 17 a m b ie n t te m p e r a tu r e ( k ) time (h) october november december january february march 0 0.5 1 1.5 2 2.5 3 3.5 a v e r a g e w in d s p e e d ( m /s ) (a) (b) (c) sameer teref azeez al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 3656 (2023) 44 4.1 effect of working fluid mass flow rate on the system performance figures 6(a) and (b) show the hourly temperature changes at the pv surface and the wf outlet from 8:00 to 16:00 for four different mass flow rates of 20, 30, 40, and 50 kg/h (laminar regime).it should be noted that the investigations are carried out on a typical day in august for the system, whose two parts are covered by a glass cover (glazed pvt and glazed st). according to the graph, regardless of mass flow rate, as solar irradiation and ambient temperature rise due to the system's absorption of more heat, the surface temperature and wf outlet temperature rise.for example, at a flow rate of 20 kg/h at around noon, the system has the highest temperatures in the cells and the wf outlet, which are, respectively, 318.6 and 322 k. by increasing the mass rate of the wf from 20 to 50 kg/h, the heat transfer coefficient in the flow increases, and as a result, the heat transfer from the surface that absorbs solar irradiation to the wf also increases. therefore, based on fig. 6(a), due to the increment in absorbing heat from the system, the temperature of the pv surface decreases. it is worth mentioning that lowering the surface temperature helps to improve the useful lifespan and electrical efficiency of the pv cells. on the other hand, the results show that the increase in the mass rate leads to a reduction in the wf outlet temperature (see fig. 6(b)), which is because of the decline in wf residence time in the tube. by increasing the mass flow rate from 20 to 50 kg/h, the pv surface temperature and the outlet temperature decrease on average by 3.2 and 7.4 k, respectively. to better understand the temperature distribution on the pv surface, fig. 7 is plotted, which shows the contours of pv surface temperature at different wf mass flow rates during a day in august. based on these contours, the inlet point experiences the lowest temperature, while by moving toward the flow direction to the end, the pv surface temperature increases. this is due to the weakening of the wf's ability to absorb heat. however, by raising the mass flow rate, we can successfully reduce this higher temperature at the end of the pvt part, especially at noon, when the maximum solar irradiation is available. fig. 6. temporal variations of the (a) pv surface temperature and (b) wf outlet temperature at different mass flow rates during a day in august. 304 306 308 310 312 314 316 318 320 7 8 9 10 11 12 13 14 15 16 17 p v s u rf ac e te m p er at u re ( k ) time (h) mass flow rate 20 (kg/h) mass flow rate 30 (kg/h) mass flow rate 40 (kg/h) mass flow rate 50 (kg/h) 302 304 306 308 310 312 314 316 318 320 322 324 7 8 9 10 11 12 13 14 15 16 17 w f o u tl et t em p er at u re ( k ) time (h) mass flow rate 20 (kg/h) mass flow rate 30 (kg/h) mass flow rate 40 (kg/h) mass flow rate 50 (kg/h) (a) (b) sameer teref azeez al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 3656 (2023) 45 fig. 7. contours of pv surface temperature at different wf mass flow rates and time during a day in august. the performance of the pvt and st has been investigated from the perspectives of energy and exergy. figures 8(a) and (b) show the temporal variations in thermal power and rate of energization at different mass flow rates during an august day. despite the decrease in outlet temperature, the thermal power increases with an increase in the mass flow rate of the wf, which indicates the dominance of the flow rate increment over the reduction in the outlet temperature. in spite of the reduction in outlet temperature due to the increase in wf mass flow rate, the amount of heat absorption becomes higher, leading to an increase in the thermal power of the system. from the standpoint of exergy, as the mass flow rate increases, the rate of thermal exergy decreases. according to eq. (11), besides the mass flow rate and inlet and outlet temperatures, the thermal energy depends on the ambient temperature. in fact, by decreasing the outlet temperature, the temperature difference between the wf temperature and the ambient temperature decreases, causing a decrease in energy. raising the mass flow rate of the wf from 20 to 50 kg/h, the daily average of thermal power increases by about 65.33 w, which is equivalent to approximately a 22% improvement (see fig. 8(a)). on the other hand, this increase in mass flow rate causes the average daily thermal exchange rate to drop by about 40.1% (see fig. 8(b)). pv temperature (k) time (h) 9:00 11:00 13:00 15:00 mass flow rate 20 (kg/h) mass flow rate 30 (kg/h) mass flow rate 40 (kg/h) mass flow rate 50 (kg/h) sameer teref azeez al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 3656 (2023) 46 fig. 8. temporal variations of the (a) thermal power and (b) rate of thermal exergy at different mass flow rates during a day in august. as mentioned earlier, increasing the wf mass flow rate leads to a reduction in the pv surface temperature. the cells' temperature has an inverse relationship with the electrical power, where its reduction improves the electrical performance of the system in terms of both energy and exergy, as shown in fig. 9. according to the results, the maximum electrical power generated by the system at the peak of solar irradiation for mass flow rates of 20 and 50 kg/h is about 27.2 and 27.7 w, respectively. considering the average electrical power produced during the day, using a mass flow rate of 50 kg/h improves the generated electricity by about 1.5% compared to the lowest amount of mass flow rate. moreover, based on eq. (12), the whole electrical power is considered useful energy; therefore, the electrical energy and exergy are the same. finally, according to the results presented in this section, a mass flow rate of 50 kg/h is selected for the rest of the investigations. fig. 10 demonstrates the average thermal and electrical efficiencies of the (glazed) pvt/(glazed) st system at different mass flow rates throughout the course of a day in august. based on the earlier discussion, the mass flow rate of 50 kg/h possesses the highest thermal and electrical powers. consequently, at this mass flow rate, the system reflects maximum thermal and electrical efficiencies of 40.7% and 16.23%, respectively. these efficiencies are 2.65% and 0.13% higher than the efficiencies produced once the mass flow rate of 20 kg/h is used. 75 125 175 225 275 325 375 425 475 525 7 8 9 10 11 12 13 14 15 16 17 t h er m al p o w er ( w ) time (h) mass flow rate 20 (kg/h) mass flow rate 30 (kg/h) mass flow rate 40 (kg/h) mass flow rate 50 (kg/h) 0 2 4 6 8 10 12 7 8 9 10 11 12 13 14 15 16 17 t h er m al e x er g y ( w ) time (h) mass flow rate 20 (kg/h) mass flow rate 30 (kg/h) mass flow rate 40 (kg/h) mass flow rate 50 (kg/h) (a) (b) sameer teref azeez al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 3656 (2023) 47 fig. 9. temporal variations of the electrical power and rate of electrical exergy at different mass flow rates during a day in august. fig. 10. average thermal and electrical efficiencies of (glazed)pvt/(glazed)st system at different mass flow rates during a day in august. 4.2 effect of using glass cover on different sections of the system the installation of a glass cover at the top of each system section, namely, pvt and st, traps heat within the system, thereby reducing heat loss to the environment and enhancing thermal efficiency [4]. therefore, in this section, the effect of using glass in two different parts of the pvt/st system is investigated. for this purpose, four different modes are considered, including a system without a glass cover (pvt/st), an all-glass system (glazed) pvt/(glazed) st, only the pvt part with a glass cover (glazed) pvt/st), and only the st part with a glass cover (pvt/(glazed) st). figures 11(a) and (b) depict the temporal variations of the pv surface and wf outlet temperatures for different pvt and st with and without glass cover on various parts on an august day at a mass flow rate of 50 kg/h. regarding fig. 11(a), the pvt with a glass cover (glazed pvt) has the highest surface temperature due to the greenhouse effect between the cover and the pv cells inside the air gap; consequently, removing the glass reduces the surface temperature of the solar cell. on average, if a glass cover is used in the pvt system, the surface temperature increases by about 2.6 k compared to the case without a glass cover. however, removing the glass from the pvt part reduces the wf outlet temperature. comparing the effects of using a glass cover on two parts on the outlet temperature, the glass has the greatest effect on the st section, section 1: mass flow rate study (laminar regime, (glazed)pvt-(glazed)st) 0 3 6 9 12 15 18 21 24 27 30 5 10 15 20 25 30 8 9 10 11 12 13 14 15 16 e le ct ri ca l ex er g y ( w ) e le ct ri ca l p o w er ( w ) time (h) mass flow rate 20 (kg/h) mass flow rate 30 (kg/h) mass flow rate 40 (kg/h) mass flow rate 50 (kg/h) mass flow rate 20 (kg/h) mass flow rate 30 (kg/h) mass flow rate 40 (kg/h) mass flow rate 50 (kg/h) 38.05 39.16 39.9 40.7 16.1 16.16 16.2 16.23 0 5 10 15 20 25 30 35 40 45 50 20 30 40 50 e ff ic ie n c y ( % ) mass flow rate (kg/h) thermal efficiency electrical efficiency sameer teref azeez al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 3656 (2023) 48 where the removal of the glass has caused a further decrease in the temperature of the wf outlet, as can be seen in fig. 11(b). as a result, the lowest temperature of the outlet fluid belongs to the pvt/st system. if the glass cover is used in both parts, (glazed) pvt and (glazed) st, the wf outlet temperature increases by about 2.35 k compared to the case without the glass cover. fig. 11. temporal variations of the (a) pv surface temperature and (b) wf outlet temperature for different pvt/st with and without glass cover on various parts at the mass flow rate of 50 kg/h during a day in august. the average thermal and electrical power and efficiency for various pvts and sts with and without glass covers at a mass flow rate of 50 kg/h during an august day are depicted in figs. 12(a) and (b).fig. 12(a) shows that if both components are equipped with a glass cover, the highest thermal power and the lowest electrical power are obtained. the glazed pvt/st system has the ability to produce about 86% more thermal power than the system without a glass cover. but on the other hand, if the glass is used on the pvt part, the electrical power decreases by about 1.5 w due to the increase in cell temperature. the pvt/st system in which the st section is equipped with a glass cover improves its thermal power by 71.7 w (equal to about 26.9%) compared to the combined system in which the pvt section is equipped with a glass cover. according to fig. 12(b), using a glass cover on top of the st part has a greater effect on thermal efficiency compared to the pvt part. for instance, implementing glass in the st part increases the thermal efficiency by 11.95% in comparison with the pvt/st system, while employing glass in the pvt part only increases the thermal efficiency by 2.28%. the maximum improvement of 14.4% can be achieved once both parts are covered by glass. moreover, the effect of using a glass cover on average electrical efficiency is minimal. fig. 13 depicts the average rate of thermal and electrical energy for different pvts and sts with and without glass covers at a mass flow rate of 50 kg/h during a day in august. the results show that the (glazed) pvt/(glazed) st system has the highest rate of thermal exchange, which is 264% greater than the pvt/st system.however, adding 300 302 304 306 308 310 312 314 7 8 9 10 11 12 13 14 15 16 17 w f o u tl et t em p er at u re ( k ) time (h) (glazed)pvt/(glazed)st pvt/(glazed)st (glazed)pvt/st pvt/st 302 304 306 308 310 312 314 316 7 8 9 10 11 12 13 14 15 16 17 p v s u rf ac e te m p er at u re ( k ) time (h) (glazed)pvt/(glazed)st pvt/(glazed)st (glazed)pvt/st pvt/st (a) (b) sameer teref azeez al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 3656 (2023) 49 a glass cover to the pvt part reduces the rate of electrical energy.furthermore, the effect of using a glass cover in the st part is more pronounced than in the pvt part, with the pvt/(glazed)st system having 67% more thermal energy than the (glazed)pvt/st system. according to the results presented in this section, in order to achieve maximum electrical power, a system without glass in the pvt section should be used, while the presence of glass in the st section increases the thermal power significantly. as a result, the pvt/(glazed)st system is chosen for additional research. fig. 12. average thermal and electrical (a) power and (b) efficiencies for different pvt/st with and without glass cover on various parts at the mass flow rate of 50 kg/h during a day in august. 0 50 100 150 200 250 300 350 400 450 average thermal power average electrical power g e n e ra te d p o w e r (w ) (glazed)pvt/(glazed)st pvt/(glazed)st (glazed)pvt/st pvt/st (a) 40.7 38.25 28.58 26.3 16.23 16.25 16.23 16.25 0 5 10 15 20 25 30 35 40 45 50 e ff ic ie n c y ( % ) thermal efficiency electrical efficiency (b) sameer teref azeez al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 3656 (2023) 50 fig. 13 average rate of thermal and electrical exergy for different pvt/st with and without glass cover on various parts at the mass flow rate of 50 kg/h during a day in august. 4.3 yearly performance of the system according to the weather conditions reported at the beginning of the results section, the performance of the pvt/(glazed)st system for the selected mass flow rate of 50 kg/h is presented in fig. 15 for a typical day in each month. as seen in fig. 15(a), both thermal and electrical power are at their peaks in the summer due to both sections of the system's ability to collect more solar energy. therefore, the highest average thermal and electrical power produced by the system occurs in august, which is equivalent to about 338.3 and 24 w, respectively, because of the high radiation and ambient temperature in this month. on the other hand, due to the severe decrease in ambient temperature and solar irradiation in january, the system produces the lowest average thermal and electrical power of roughly 180.4 and 14.9 w, respectively. similar results can be observed for the rate of thermal and electrical exergy, as shown in fig. 15(b), where the highest rate of exergy is obtained in summer and the lowest rate in winter. 20 21 22 23 24 25 0 1 2 3 4 5 6 (g la ze d )p v t /( g la ze d )s t p v t /( g la ze d )s t (g la ze d )p v t /s t p v t /s t r at e o f el ec tr ic al e x er g y ( w ) r at e o f th er m al e x er g y ( w ) average rate of thermal exergy average rate of electrical exergy sameer teref azeez al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 3656 (2023) 51 fig. 14. monthly performance of the pvt/(glazed)st system from (a) energy and (b) exergy viewpoints. 4.4 environmental analysis: co2 reduction as one of the most prominent greenhouse gases, co2 has crucial impacts on global climate change and air pollution. consequently, using a clean energy system like the one proposed in this study can reduce the production of co2. using eq. (14) and based on the calculated thermal and electrical power in previous sections, the amounts of co2 reduction for different cases are determined. in a typical august day, figs. 15(a) and (b) show the amount of co2 reduction for the (glazed) pvt and (glazed) st systems at different mass flow rates, as well as four different pvt and st systems with and without glass covers (presented in section 4.2).by increasing the wf mass flow rate, the amount of co2 reduction increases due to the increment in both the thermal and electrical power of the system. for example, using the system at a mass flow rate of 20 kg/h reduces co2 by approximately 70.7 kg, while increasing the mass flow rate to 50 kg/h increases this amount by 12.1 kg (a 17.1% improvement as shown in fig. 15(a)). as discussed earlier, using a glass cover dramatically increases the thermal power of both the pvt and st sections, while negatively affecting the electricity produced by the pv cells. as a result, the maximum and minimum co2 reductions belong to the (glazed) pvt/(glazed) st and pvt/st systems, as shown in fig. 15(b), where the amount of co2 emission reduces from around 82.8 to 50.15 kg (a 39.4% decrease in co2 reduction). furthermore, using (glazed) pvt/st and pvt/(glazed) st systems could reduce co2 emissions by approximately 73.2 and 59.4 kg, respectively. it should be noted that the pvt/(glazed)st system is chosen for monthly performance evaluation because of its superior electrical performance, despite having a lower co2 reduction than the pvt/(glazed)st system. 0 5 10 15 20 25 0 0.5 1 1.5 2 2.5 3 3.5 4 e le ct ri ca l ex er g y ( w ) t h er m al e x er g y ( w ) thermal exergy electrical exergy 0 50 100 150 200 250 300 350 400 t h er m al p o w er ( w ) thermal power electrical power (a) (b) sameer teref azeez al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 3656 (2023) 52 fig. 15. co2 reduction for (a) (glazed)pvt/(glazed)st system at different mass flow rates and (b) four different pvt/st systems with and without glass cover on a typical day in august. finally, fig. 16 depicts the co2 reduction on a typical day of each month for the pvt/(glazed)st system at a mass flow rate of 50 kg/h. since the total average power of the system has a direct relationship with the reduction of co2, the highest amount of co2 reduction can be absorbed in august, which is followed by july and september. on the other hand, the lowest value of co2 reduction is not achieved in january (the lowest thermal and electrical production occur in this month, as illustrated in fig. 15(a)). due to the lower sunny days [25], it belongs to february by 10.7 kg, and as a result, the total working hours reported for this month in fig. 2. ultimately, using the pvt/(glazed)st system can reduce co2 emissions by 426.3 kg per year. fig. 16. monthly co2 reduction for pvt/(glazed)st system at the mass flow rate of 50 kg/h on a typical day in 12 months. 0 10 20 30 40 50 60 70 80 90 (glazed)pvt-(glazed)st pvt-(glazed)st (glazed)pvt-st pvt-st c o 2 re d u ct io n ( k g ) 50 55 60 65 70 75 80 85 mass flow rate 20 (kg/h)mass flow rate 30 (kg/h)mass flow rate 40 (kg/h)mass flow rate 50 (kg/h) c o 2 re d u ct io n ( k g ) (a) (b) 0 10 20 30 40 50 60 70 80 c o 2 re d u ct io n ( k g ) sameer teref azeez al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 3656 (2023) 53 5. conclusion the performance of a hybrid system called pvt/st, which consists of a photovoltaic thermal module and a solar flat collector connected in series, was investigated in this study. to investigate the annual performance of the system from energy, exergy, and environmental perspectives, a numerical simulation was conducted by considering the weather conditions in mashhad, iran. moreover, the effects of the working fluid mass flow rate (20–50 kg/h) and the influence of using a glass cover on each part of the pvt/st system were investigated in august. finally, the effects of these parameters on co2 reduction were discussed. the results of this research indicate:  by increasing the working fluid's mass flow rate from 20 to 50 kg/h in the (glazed) pvt/(glazed) st system, both the pv surface temperature and the working fluid's outlet temperature decreased by an average of 3.2 and 7.4 k, respectively, improving both thermal (22%) and electrical (1.5%) power. however, with this increment in mass flow rate, the thermal entropy decreased by 40.1%.  the glazed pvt/st system generated approximately 86% and 264% more thermal power and energy than the pvt/st system. due to the increase in temperature of the pv cells, using a glass cover on the pv component decreased the electrical power by about 1.5 w.  the systems in august and january could produce the highest and lowest average thermal powers, approximately 338.3 and 180.4 w, respectively. furthermore, the generated electricity for these months was 24.9 and 14.9 w, respectively.  the co2 reduction increased as the mass flow rate rose due to an increase in both the system’s thermal and electrical power, e.g., increasing the mass flow rate from 20 to 50 kg/h improved the amount of co2 reduction by approximately 17.1%. moreover, using glazed pvt or glazed st instead of pvt or st enhanced the amount of co2 reduction by 39.4%. finally, employing pvt or (glazed) st systems could reduce the production of co2 by 426.3 kg in a year. nomenclature a area (m2) cp specific heat capacity (j/kg.k) 𝐸�̇� rate of exergy (w) �̇� power (w) h convection heat transfer coefficient (w/m2.k) i solar irradiation (w/m2) k thermal conductivity coefficient (w/m.k) �̇� mass flow rate (kg/s) p pressure (pa) t temperature (k) t time (s) v velocity (m/s) greeks 𝜌 density (kg/m3) 𝛼 absorptivity η reference of energy efficiency (%) τg glass transmissivity µ dynamic viscosity (kg/m.s) ϕ the yearly co2 reduction subscripts abs absorber amb ambient el electrical eq equivalent eff effective f fluid in inlet out outlet pv photovoltaic cell s solid th thermal abbreviation eva ethylene-vinyl acetate pv photovoltaic unit pvt photovoltaic thermal module pvt/st hybrid photovoltaic thermal system and solar thermal collector st solar thermal collector wf working fluid sameer teref azeez al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 3656 (2023) 54 6. references [1] a. kazemian, m. khatibi, s.r. maadi, t. ma. performance optimization of a nanofluidbased photovoltaic thermal system integrated with nano-enhanced phase change material. applied energy. 295 (2021) 116859. 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[28] https://re.jrc.ec.europa.eu. https://www.meteoblue.com/en/weather/historyclimate/climatemodelled/mashhad_iran_124665 https://www.meteoblue.com/en/weather/historyclimate/climatemodelled/mashhad_iran_124665 https://www.meteoblue.com/en/weather/historyclimate/climatemodelled/mashhad_iran_124665 https://re.jrc.ec.europa.eu/ (2023) 36-56، صفحة 1، العدد19مجلة الخوارزمي الهندسية المجلد سمير ترف عزيز 56 مشترك من وحدة حرارية لنظام (3eوالبيئة )التحليل السنوي للطاقة، واالكسيرجي، كهروضوئية ومجمع حراري شمسي سمير ترف عزيز العارضي* محمد مقيمان** *،**جامعة فردوسي في مشهد/ مشهد/ ايران eng.sameer3@gmail.com*البريد االلكتروني: moghiman@um.ac.ir**البريد االلكتروني: الخالصة عدديًا من منظور الطاقة، والطاقة الخارجية، (pvt / st) يتم تحليل األداء السنوي لنظام هجين لنظام حراري ضوئي مستو وجامع حراري شمسي طاقة حرارية وطاقة أعلى من األنظمة الحرارية والبيئة )تقليل ثاني أكسيد الكربون(. يمكن لهذا النظام إنتاج طاقة كهربائية وحرارية في نفس الوقت وله ( التحقيق في آثار معدل 1الكهروضوئية التقليدية. لهذا الغرض ، تم تطوير نموذج رقمي عابر ثالثي األبعاد للتحقق من أداء النظام في أربع خطوات رئيسية: ) ( التحقيق في آثار استخدام زجاج 2ة ؛ والديناميكا الحرارية ألداء النظام ، )كجم / ساعة( على سلوك درجة الحرار 50إلى 20التدفق الكتلي لسائل العمل ) ( فحص الكربون . تقليل 4( تقييم التحليل السنوي الستهالك الطاقة والطاقة للنظام في ظروف الطقس في مشهد، و )3الغطاء على أجزاء مختلفة من النظام، ) 20)المزجج(، تؤدي زيادة معدل التدفق الكتلي لسائل العمل من st (المزجج) / pvt نتائج أنه بالنسبة لنظامثنائي أكسيد باستخدام النظام المقترح تظهر ال ٪. 40.1٪ في الطاقة الحرارية والكهربائية. على التوالى. ومع ذلك، تقل الطاقة الحرارية للنظام بنسبة 1.5٪ و 22كجم / ساعة إلى تحسن بنسبة 50إلى واستناداً .pvt / st ٪ أكثر من نظام264٪ ومعدل طاقة حرارية بنسبة 86طاقة حرارية أكثر بنسبة st (المزجج) / pvt ينتج نظام باإلضافة إلى ذلك ، ي وات على التوالي. تزداد كمية تقليل ثان 24و 338.3للطاقة الحرارية والكهربائية في شهر أغسطس بحوالي إلى التحليل السنوي، تم إنتاج أعلى متوسط )المزجج( من إنتاج ثاني أكسيد / pvt أكسيد الكربون مع ارتفاع معدالت تدفق الكتلة واستخدام زجاج الغطاء في كال الجزأين. يمكن أن يقلل استخدام نظام .كجم سنويًا 426.3الكربون بمقدار mailto:eng.sameer3@gmail.com 1. introduction 2. numerical modeling 2.1 physical model 2.2 assumptions 2.3 governing equations 2.4 boundary conditions 2.5 performance evaluation method 2.6 environmental analysis: co2 reduction 2.7 numerical simulation procedure 2.8 grid and time-step independence study 3. model validation 4. results and discussion 4.1 effect of working fluid mass flow rate on the system performance 4.2 effect of using glass cover on different sections of the system 4.3 yearly performance of the system 4.4 environmental analysis: co2 reduction 5. conclusion 6. references this is an open access article under the cc by license : al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 21, no. 4, december, (2025), pp. 4564 rabbit-256 optimisation for secure blockchain hashing in iothealthcare data khalid jamal jadaa1*, aymen mudheher badr2, waleed noori hussein3, and latifah munirah kamarudin4 1 department of computer engineering, college of engineering, university of diyala, diyala, iraq 2 college of medicine, university of diyala, diyala, iraq 3 al-zahraa college of medicine, university of basrah, basrah, iraq 4 centre of excellence for advanced sensor technology (ceastech), perlis, malaysia 4 department of computer and communication engineering, university malaysia perlis, perlis, malaysia *corresponding author’s e-mail: kalid.jamal.jadaa@gmail.com (received 8 july 2025; revised 5 october 2025; accepted 27 october 2025; published 1 december 2025) https://doi.org/10.22153/kej.2025.10.001 abstract the recent trend towards the use of a blockchain as a means to guarantee the security of health data has raised concerns with regard to its applicability in internet of things (iot) scenarios due to computationally heavy primitives (e.g. hashing functions) and lack of scalability. as a solution to this problem, this article introduces rabbit-256: an addition–rotation– xor-based sponge construction derived from the rabbit stream cipher that is twisted and adapted to a lightweight hash function, suitably adapted for distributed solutions in healthcare systems with a blockchain nature. rabbit-256 is a lightweight encryption cipher that wears the mask of a hash function but with better diffusion and avalanche through an official buildup in merkle trees. the presented system is evaluated using common cryptographic measures against sha256, i.e. grid operators of 100, 500, and 1000 inputs for the avalanche effect, hamming distance, and mean standard deviation. we observe that rabbit-256 exhibits a higher security margin and lower computational overhead, and thus, it is an optimal alternative to resource-constrained iot systems given its resistance against attacks. although the current work is developed in simulation, rabbit-256 can be utilised for actual deployment to ensure the privacy of e-health records and medical sensor data in iot and clinical services over a blockchain. in the future, we will focus on hardware design, energy efficiency, and integration (i.e. to be compliant with the health insurance portability and accountability act in the u.s. and the general data protection regulation in europe). keywords: healthcare; hashing; medical internet of things; security; cloud computing; blockchain 1. introduction the dispersion of processing power worldwide has enabled the development of various technologies, including blockchain technology [1]. examples include coins, such as bitcoins, which are recorded publicly and temporarily. the most interesting aspect of this research is the public element; that is, anyone in the world can download the code and either ‘mine’ for bitcoins or participate in new network concepts created on the ethereum platform [2]. as blockchain technology rapidly develops, it is currently being implemented in various medical data scenarios [3], personal data protection, and data allocation systems. it is even used to stimulate the inclusion of renewable energy sources in power grids, which is beyond its original application in the scope of cryptocurrency. thus, reducing emissions in the global shipping industry enables banks to process transfers faster at lower costs [4]. mailto:kalid.jamal.jadaa@gmail.com https://doi.org/10.22153/kej.2025.10.001 khalid jamal jadaa al-khwarizmi engineering journal, vol. 21, no.4, pp. 4564 (2025) 46 the cryptographic algorithm (rabbit 128/128 bit) is the foundation of the blockchain hash algorithm proposed in the current work. this highly efficient algorithm is used to model the blockchain hash algorithm design, providing resilient security and integrity of data. furthermore, high speed can be achieved for the purpose of data transfer. this scheme can truly improve the security and efficiency of data processing in a blockchain. through the use of the internet of things (iot) technology in health systems, patients can be remotely diagnosed. their health can be analysed online and even remotely observed in real time. however, major hurdles exist for the entire digital transformation, including privacy management. as a novel technology, blockchain provides a possible solution to the aforementioned problems by authenticating and securely storing data. however, the mainstream use of blockchain necessitates costly commands, such as hashing functions (specifically sha-256) and cryptographic primitives, which require heavy computations. this situation is the reason why we will likely not see the use of blockchain technology in low-power and similar devices within the iot paradigm. the current article primarily discusses the aforementioned limitations and attempts to address them. a lightweight hash function based on the rabbit stream cipher is included. in this article, we demonstrate a hardware-efficient (and easily scalable) rabbit-256 function. the following research questions are posed: 1. could rabbit-256 be used as an encryption that is sufficiently strong, and perhaps, less computationally expensive, and with a lower power requirement than sha-256 for technologies such as iot? 2. how does rabbit-256 function when subjected to key cryptographic properties, such as the avalanche effect and hamming distance (hd)? 3. what are the implications of blockchain-based healthcare systems on scalability and regulations? to resolve these problems, the research presented here makes the following contributions: 1. a new adaptation of the rabbit stream cipher for encryption in blockchain security. 2. experimental evaluation with different sizes of datasets 3. promotion of the light encryption method for a blockchain-based healthcare system with a holistic solution the current work contributes a step towards paving the way for the implementation of improved device applications in the future, bridging the gap between the limitations of iot devices and blockchain security in healthcare. 1.1. immutability and compatibility concepts although several features are associated with blockchain security, the two most critical ones are consensus and immutability [5]. in a distributed blockchain network, the most critical feature is the capability of nodes to agree on the authentic state of a network and the validity of transactions. consensus algorithms are basically used to reach consensus. [6]. for a clear explanation, consensus is the agreement of nodes on the actual state of a network and the legitimacy of transactions; meanwhile, immutability is the capability of blockchains to block changes made to valid transactions. although cryptocurrencies are the most widely used technology at present, they can also be utilised for other digital data that have no connection to financial transactions. in blockchain networks, immutability and consensus work together to produce a data protection system. one of the key tasks of a consensus algorithm is to ensure that all involved parties agree on the current state of a network and the rules of a system are strictly followed. after simultaneously verifying the validity of each new dataset, the role of immutability ensures the integrity of data and transaction records [7]. 1.2. use of cryptography to secure blockchains one of the key factors for ensuring the security of blockchain networks is the adoption of cryptographic hashing operations. hashing is the process of generating output values with a fixed length and not considering the size of the input. the result of hash changes in accordance with changes that occur in the input data, and the data remain the same if the input data do not change [8]. in a blockchain, data blocks are unambiguously identified as unique identifiers based on their hash, which is generated for each block built on the hash of the previous block. this structure is called a blockchain. a blockchain confirms transactions to the rest of the network. if block data are modified, then the hash value of this block should also be changed to preserve the immutability principle (integrity) of a blockchain [9]. consensus algorithms, such as proof of work in bitcoins, use hashing to check the validity of transactions and for mining. the sha-256 function (a hash of 256 bits) is commonly employed [10]. in addition, cryptography is used in the preservation khalid jamal jadaa al-khwarizmi engineering journal, vol. 21, no.4, pp. 4564 (2025) 47 of transaction information and crypto wallets with asymmetric encryption. users can receive and transmit payments by using public key/private key pairs [11]. the ownership of transferred coins is verified using digital signatures that are created with private keys. wallet balances are protected through authentication by using an asymmetrically encrypted private key. the remainder of this paper is organised as follows. section 2 provides a quick overview of related background and literature on blockchain security and healthcare data management. the proposed rabbit-256-based optimisation algorithm for blockchain hashing is described in section 3, including its detailed design and implementation procedure. the description of the modified rabbit256 algorithm is provided in section 4, whilst sections 5 and 6 respectively present the experiment setup and discuss the results obtained by the performance evaluation and security analysis of the proposed algorithm. finally, section 7 concludes the article with a synthesis of the key findings, contributions and future research directions. 2. related work 2.1. blockchain technique based on iot blockchain technology is considered a proposed solution to the security and privacy issues in iot networks. blocks can be distributed amongst devices, providing provable techniques for the future. the influences of blockchain technology and cryptocurrency on the development of it in society are the subject of prospective research. such research is crucial because several stakeholders, including the united nations [12], should start dealing with these technologies to understand how they work and learn from them. block-based iot schemes proposed by academicians exhibit the potential for effectively incorporating resourceconstrained iot devices into a blockchain. in [13], a decentralised access control design for iot based on a blockchain was introduced with the capability to accommodate numerous devices. involving iot devices in a blockchain network is challenging due to constrained resources. instead, a management hub ‘talks’ to a blockchain network for these devices. in [14], the authors provided a collaborative mining network to deal with the restricted communication and computational requirements of mobile iot devices. they used resources that remained free beyond mining devices and cloud–edge to perform some tasks related to exploitation in mobile blockchains. in [15], a decentralised capability-based access control architecture, called iot-consortium capabilitybased access control, for iot consortium networks was presented. this structure adopted a blockchain database for high throughput performance, overcoming conflicts from data leakage and failure of centralised processing systems. in [16], a collaborative computing architecture was introduced to satisfy the quantum computing requirements of a blockchain-enabled iot. it consists of computer servers that are virtualised in numerous data access points to form a resource pool with elasticity. data are collected based on block size, and a correct nonce is created using blockchain calculation. security is further achieved through a cloud cache-based storage of the block, whilst adding its hash value to the blockchain. 2.2. hash function with a blockchain the significance and roles of hashes in the blockchain architecture have been recognised. here, we present studies related to this subject. in [17], the authors presented a robust but straightforward hashing mechanism that could be used with a blockchain to safeguard the confidential data of healthcare internet of medical things systems. this overall process reduces energy utilisation and computational requirements, thus; it is useful for medical devices with restricted resources in contrast with the traditional hash reporter. the test results indicated good avalanche effects, unpredictability and anti-attack performance. the proposed mechanism is efficient and reliable for applications in healthcare iot. accordingly, we introduce a novel hash function that uses a genetic algorithm to improve data integrity for blockchain-based healthcare systems. the researchers developed the genetic algorithm-based hashing technique (gahbt) for health data categorisation and preservation. this technique provides more robustness against data collision and higher randomness than the conventional method. studies have confirmed that the gahbt scheme provides progressive data security and is less affected by common cryptographic attacks. the paper clarion recognises this idea as a successful solution to protecting patient data in blockchain healthcare systems and discusses how it can be employed in the scalable management of healthcare data. [18]. to guarantee transparency and data accuracy whilst eliminating intermediaries, a document’s hash information and transactions are registered in a blockchain. khalid jamal jadaa al-khwarizmi engineering journal, vol. 21, no.4, pp. 4564 (2025) 48 in [19], the edwards-curve digital signature algorithm (eddsa) was used in a secure and strong pseudorandom number generator by comparing it with the elliptic curve digital signature algorithm. accordingly, researchers have proposed adopting eddsa to generate hash functions in transactions. in [20], the researchers suggested using chameleon hash functions to modify one block in a blockchain without affecting others. they employed multiparty computing to recover a shared trapdoor key for block debugging. revision occurs when lead auditors digitally sign proposed modifications, eliminating the need for a trusted party. another trapdoor switch has been proposed to prevent block revision without the creator’s permission. in [21], the researchers introduced policy-based chameleon segmentation with black box accountability (pchba), which enables the attribute authority to link updated transactions with accountable transaction rates by using black box accountability. public users can use the access device/black box to identify these rates. this previous study provides a foundation for pchba. recent research has significantly enhanced the body of literature on the use of lightweight cryptography (lwc) in blockchain systems for the healthcare sector. the researchers conducted experiments on lightweight algorithms with miniature-sized microcontrollers, verifying the implications of security over efficiency trade-offs on iot devices [22]. meanwhile, the current research performed a more precise analysis of lightweight cryptographic programmes and identified metrics for validation, such as hd, the avalanche effect and bit independence [23]. this line of work gave rise to a recent hash function based on the speck cipher and demonstrated that cipher reuse could provide us with secure yet efficient hashing, albeit its relation with a blockchain was not trivial [24]. although the aforementioned researchers examined blockchain in healthcare applications, they pointed out that regulatory barriers and scale and interoperability challenges were two issues points [25] [26]. in contrast, tailored lightweight hash also functions for iot, but in the sense of a trade-off between energy saving and resistance against possible system access [27]. the aforementioned studies suggest the critical requirement for the development of hashing schemes similar to rabbit-256 that maintain a potential for lightweight efficiency and simultaneously support wide cryptographic strength in addition to blockchain applications in healthcare. 3. proposed system 3.1. lwc algorithms the lwc project, launched in april 2018 by the u.s. national institute of standards and technology (nist), aims to design cryptographic algorithms for resource-constrained devices. the current work was inspired by the growing iot, in which effective and secure communication between devices must be assured for new emerging applications, such as autonomous cars and smart grid operations [28]. lightweight encryption, also known as lwc, is a form of encryption designed for devices with limited resources. to offer secure solutions for network-constrained resources, lightweight encryption technology employs less memory, fewer computational resources and lower electricity consumption. aes and sha are unsuitable for resourceconstrained iot environments because they require excessive computational resources [29]. to address this issue, low-power cryptographic devices have been developed for iot/radio-frequency identification devices. international and nist groups have defined techniques for lwc that are specifically designed for low-resource systems. figure 1 illustrates a classification of simple cryptography algorithms. khalid jamal jadaa al-khwarizmi engineering journal, vol. 21, no.4, pp. 4564 (2025) 49 fig. 2. lwc algorithms 3.2. rabbit algorithm the rabbit algorithm, which enables a powerful nonlinear mixing of the inner state between two repetitions, is particularly compact for encrypting and decrypting sensitive messages. the rabbit algorithm was introduced in 2003. one of the earliest attempts at lwc was this algorithm. it utilises 0.18 nm complementary metal–oxide–semiconductor technology and 3800 ge [30]. it employs the original messages shown in figure 2, combined with a secret key of 128 bits for encryption. the files, which are exchanged amongst authorised users, are encrypted and decrypted using the keys. each cycle uses 128 randomly chosen internal state bits to create the output block by converting plaintext into ciphertext, and vice versa, using the xor technique during encryption and decryption. eight counters with 32 bits each, one state variable with 32 bits and one carry counter bit make up the 513 bits that comprise internal state size. state variables are updated using the paired nonlinear octet function. situational variables are the minimum duration of the time promised by the counters. the basic objective of this technique is to encode 128 bits of data every iteration and generate the cipher as a big stream. the strength of encryption depends on the robust mixing of internal states over two successive repetitions. the mixing function uses the g-function related to arithmetical squaring, xor, a bitwise rotation and modulo 2 additions. the rabbit-256 algorithm has been preferred over other lightweight algorithms for blockchain applications, especially in healthcare, because it offers strong security, superior avalanche properties and lightweight performance, making it ideal for the current research. table 1 provides a comparison between rabbit-256 and other lightweight algorithms (sha-256, aes, speck, simon, present) in terms of computational efficiency, memory efficiency, power usage, avalanche effect, bit independence, hd, suitability for iot and blockchain integration [31]-[34]. khalid jamal jadaa al-khwarizmi engineering journal, vol. 21, no.4, pp. 4564 (2025) 50 table 1, comparison of rabbit-256 with other lwc algorithms feature rabbit-256 (our work) sha-256 (our work) aes (128 bits) [daemen & rijmen 2013] other lightweight ciphers (speck, simon, present) [beaulieu et al. 2015; bogdanov et al. 2007; elhajj et al. 2023] computational efficiency high moderate moderate variable (optimised for iot) memory and power usage low high moderate low avalanche effect ≈58% (strong) ≈50% not considered for hashing moderate bit independence strong strong but slower n/a varies; some ciphers are weak hd higher than sha256 lower than rabbit256 n/a lower suitability for iot excellent poor limited good blockchain integration merkle tree + blockchain heavy for iot non-straight applicable not widely tried in blockchain 3.3. key management system (kms) in a cryptosystem, managing cryptographic keys is referred to as key management, which encompasses handling key creation, transfer, storage, usage, crypto-shredding (destruction) and replacement [35]. figure 2 illustrates the basic function of the rabbit algorithm. fig. 2. basic function of the rabbit algorithm the exchange of keys is less problematic at present because of the development of public key cryptography in the 1970s. the danger of key leakage during distribution has significantly decreased since the diffie–hellman key exchange protocol was developed in 1975. this protocol made exchanging a key across an unsecured communication channel feasible. key indications can be linked to an encrypted communication as clear text by using a method that is analogous to a book code. this form of encryption was utilised by richard sorge’s code clerk; it was a code that referred to a page in a statistics handbook [36]. the symmetric encryption key used by the german army during world war 2 was a mixed type; it was composed of a privately disseminated key schedule component and a user-selected session key component for each transmission. kms is a systematic approach for generating, distributing and preserving cryptographic keys for hardware and software. it consists of client-side capacities for storing and managing keys, and back end functionality for the generation and distribution of keys [37]. key management is fundamental to the security of cryptosystems, and it has social engineering components, such as system policy, user education and organisation coordination [38]. khalid jamal jadaa al-khwarizmi engineering journal, vol. 21, no.4, pp. 4564 (2025) 51 3.4. merkle trees a merkle tree is a perfect binary tree with an associated hash function and an assignment function [39]. merkle trees (hash trees, authentication trees) are data structures used in cryptography and computer science for the purpose of efficiently checking large volumes of data for changes or consistency within a distributed system [40]. the nodes of merkle trees are essentially their leaves and inner nodes. individual data points are represented as leaf nodes, and each leaf node is associated with its unique hash value. meanwhile, non-leaf nodes connected by the hash value of their child nodes are known as internal nodes. a tree’s root node is a single hash value, which is the result of combining the hash values of its child nodes through recursive hashing [41]. if φ(𝑛) is the hash function used to compute the hash of a given input 𝑛 and ‘||’ denotes concatenation, then the equation for generating a merkle root hash can be expressed as φ(𝑛𝑝𝑎𝑟𝑒𝑛𝑡) = ℎ𝑎𝑠ℎ(φ(𝑛𝑙𝑒𝑓𝑡)||φ(𝑛𝑟𝑖𝑔ℎ𝑡)). …(1) the structure of a merkle tree comprises a full binary tree that is accompanied by a hash function and an assignment function, denoted by 𝜙, which maps the nodes in the tree to 𝜅 length strings in the set 𝑛 → φ(n) ∈ {0,1}𝑘. in particular, for any interior node (𝑛𝑝𝑎𝑟𝑒𝑛𝑡) in the tree, its two child nodes (𝑛𝑙𝑒𝑓𝑡) and (𝑛𝑟𝑖𝑔ℎ𝑡) must satisfy the condition that the assignment function φ maps 𝑛 parent to the concatenation of the values of φ (𝑛𝑝𝑎𝑟𝑒𝑛𝑡) and φ (𝑛 𝑟𝑖𝑔ℎ𝑡 ). figure 3 illustrates the process of generating a merkle tree in the proposed system after data are hashed and how to obtain the root hash. fig. 3. merkle tree for generating top hash 4. modified rabbit algorithm to work as hash in a blockchain (mrhb) cryptography is extremely important with regard to securing private information, such as medical records. with the advent of blockchain technology, a decentralisation strategy that secures data integrity and improves security is established. the current work extends the rabbit algorithm, which is an efficient and compact segmentation approach used in blockchain systems. a multilayered system is shown in figure 4, in which medical data are produced by health professionals during patient examination and diagnostics on different devices. in the second layer, the rabbit-256 algorithm is used to transform data into session unique hashes. it scrambles data by nonlinearly operating on them with random keys, increasing privacy and cryptographic resistance. the rabbit algorithm is a symmetric key stream cipher that produces a key stream by combining input data, a secret key and a nonce. the key stream is xored with the input data, and the process is repeated multiple times for security. khalid jamal jadaa al-khwarizmi engineering journal, vol. 21, no.4, pp. 4564 (2025) 52 fig. 4. structure of mrhb the basic rabbit is a stream cipher, generating a keystream for encryption, and mrhb tweaks this structure such that it functions as a hash. in mrhb, metadata (imprint time, nonce and patient id) are embedded into message blocks and then manipulated through state updates, s-box/chaotic substitutions and block mixing. the iterative aggregation processed with final compression works as a 256-bit optimised hash value for secure and lightweight healthcare blockchain applications. figure 5 illustrates a comparative view of the original rabbit cipher and the candidate mrhb hash function. fig. 5. comparative architecture of the original rabbit cipher and the proposed mrhb hash function to clarify the transformation process from a stream cipher into a hash function, the researchers detail the steps of transforming the internal state of the rabbit stream cipher into a secure, lightweight hash primitive (i.e. mrhb). the process of transforming rabbit from a stream cipher into a hash primitive (mrhb) works by using rabbit’s fast state update and nonlinear counter functions, adding deterministic seeding, block-based mixing and additional nonlinear tweaks. the objective is to create a lightweight, unkeyed 256 bits hash output that works to verify public blockchains in iot healthcare settings. design parameters: internal state: 513 bits (rabbit core state) message block size: 256 bits (32 bytes) internal word size: 32 bits output length: 256 bits (fixed) rounds per block: 4 rabbit state updates (configurable for security/performance tradeoff) transformation steps: 1initialisation rabbit’s secret key/iv is replaced with fixed public constants. a 256 bits initial chaining value (h₀) is derived from predefined constants. this step ensures that identical input messages always produce identical output (public verifiability). 2message preprocessing input message (metadata ∥ payload) is serialised and padded using merkle–damgård style: append 0×80, followed by 0 bytes, and finally, a 64 bits big-endian message length (bits). the padded message is divided into 256 bits blocks: m[1..n]. 3per-block processing -to put through a piece block mi (where i ranges from 1 to n): a. seed creation: a deterministic seed is created from the current chaining value mᵢ and the block counter combined. b. rabbit keystream generation: this seed is used as input for rabbit (mapping it onto an internal state) and then a 256 bits keystream kᵢ is calculated. c. block transformation: the xor function is used on mᵢ with kᵢ and tᵢ is obtained. d. nonlinear substitution: byte-per-byte is substituted with a substitution box uᵢ = sbox(tᵢ), which can be an aes s-box or a simple chaotic map as an option. e. hash accumulation: the chaining value is changed nonlinearly: khalid jamal jadaa al-khwarizmi engineering journal, vol. 21, no.4, pp. 4564 (2025) 53 hᵢ is equal to rabbit round (hᵢ₋₁ xor uᵢ), where rabbit round refers to a single update of the rabbit state that uses uᵢ as the input. this method prevents simple xor-based accumulation and strengthens defence against collision-style attacks. 4finalisation the length of the encoded message is added to the state once all the blocks are processed . four extra rabbit updates are performed using a zero block to ensure that all leftover structures are mixed . the final 256 bits chaining value is taken and used as the resulting hash. 5output a 256 bits mrhb digest is generated as the final hash. the fixed and accessible digest can be employed as a blockchain system’s block header hash or a merkle leaf. the resulting encrypted data are the hash, merged with randomly generated keys. figure 6 shows the encrypted data for private healthcare. fig. 6. private healthcare data after encryption in the third layer, a merkle tree is constructed based on hashes from several sessions. this tree guarantees security in transmitting data and avoiding spurious file transmission. every leaf node is a hash of a session, and its parent nodes are the hashes of pairs of child nodes. file integrity verification is achieved by network users by comparing hashes with the root hash of the merkle tree. any interference will cause a mismatch between the root hash that is stored and the calculated one, indicating tampering. to ensure data integrity, the root hash of the merkle tree is stored in a blockchain and in a new block. the use of a distributed ledger is beneficial because it can store multiple network nodes. one of the important features of adopting blockchain technology is that the blocks are essentially immutable and cannot be tampered with after they are added, and thus, they are considered highly secure. by relying on data replication technology in the network, adopting this technology helps reduce individual failures and mitigate the severity of attacks, which, in turn, leads to an increase in reliability. figure 7 and algorithm 1 illustrate the flowchart and pseudocode that present the methodology of the proposed rabbit-256-based blockchain hashing for healthcare data security, respectively. khalid jamal jadaa al-khwarizmi engineering journal, vol. 21, no.4, pp. 4564 (2025) 54 fig. 7. flowchart of the research methodology algorithm mrhb_hash(input: message) output: hash_value (256-bit) 1 initialization : define internal state as rabbit’s original structure: • 8 state words (32-bit each) • 8 counters (32-bit each) • 1 carry bit total = 513 bits. initialize all state variables with fixed public constants. 2preprocessing: pad message using merkle–damgård style : append 0x80, followed by zeros, then append 64bit message length (in bits). split padded message into 256-bit blocks m[1..n] . 3for each block mᵢ: a) generate rabbit keystream (4 rounds of state update using g-function .) b) mix block with keystream : temp = mᵢ ⊕ keystream c) nonlinear layer : temp = sbox(temp) (aes s-box or chaotic map applied bytewise) d) hash accumulation : hash_state = rabbitround(hash_state ⊕ temp) 4finalization : inject total message length into the state . run 4 additional rabbit rounds with zero input blocks. extract 256 bits of the final state (concatenate 4 × 64-bit words) as hash_value. 5return hash_value. algorithm 1. pseudocode block of the modified rabbit-256 hashing process 5. simulation environment to ensure reproducibility, all experiments in the current research were performed in a managed software–hardware setup. the specifications are summarised below: • hardware platform: processor: intel core i7-11800h @ 2.30 ghz (8 cores, 16 threads) memory: 16 gb ddr4 ram storage: 512 gb ssd operating system: windows 11 pro, 64 bit • software environment: programming language: python 3.11 libraries: numpy (v1.26), scipy (v1.12), matplotlib (v3.8) and custom cryptographic routines for rabbit and sha-256 simulation ide: jupyter notebook/pycharm community edition randomness source: python’s built-in secrets library for nonce/iv generation • dataset and experimental setup: input sizes: 100, 500 and 1000 random test messages (each 128-bit block is padded) message metadata: time stamp, patient id and nonce values were included to simulate healthcare transactions. evaluation metrics: the avalanche effect, hd and mean standard deviation (msd). experiments were repeated on the same dataset with different seeds to validate that they were consistent. resource usage monitoring indicated that typical memory utilisation did not exceed 350 mb. it also provided evidence of suitability to resource-constrained iot-like environments with a cpu load of less than 40%. khalid jamal jadaa al-khwarizmi engineering journal, vol. 21, no.4, pp. 4564 (2025) 55 6. results and discussion hashing in the system is also examined, tested and proven effective in the following subsections. for thoroughness and to provide a full account of the studies, multiple evaluation criteria were adopted as follows: bit independence, avalanche metrics computation, hd, mean changed and msd. the framework was tested with three datasets in the current study: 100, 500 and 1000 hashes. the hash function was compared with the sha256 algorithm, which is generally employed in this area. in addition, the dimension of each hash value in the dataset is 256 bits. the hash function apparently exhibits the following property of ‘independent bit’: informally, for a hash function, proving that any subset selection of bits in the output can be generated independently from any other (which is essential for the markle–damgård structure) should be possible. through the observation of output bits, such a property can be tested, whether it is uniform or not. balancing the arab-256 hashing scheme based on different data sizes (100, 500 and 1000) is employed in the current paper. a balanced assessment can be obtained by focusing on the number 100 as a baseline, increasing it to 500 for medium-range testing, and then up to 1000 for largescale evaluation. this procedure gives rise to computational simulations but retains statistical ‘robustness’. these use cases are helpful, and they genuinely represent the healthcare situation with iot. table 2, a use of 100 hash input to determine the average of the metrics metric rabbit-256 sha-256 bic 0.0004534 0.0004580 avalanche 128.64 80.05 hd 36.58 58.44 nmcb 50.41796 50.01953 msd 73.54271 73.887815 table 2, b use of 500 hash input to determine the average of the metrics metric rabbit-256 sha-256 bic 0.0004541 0.0004574 avalanche 128.172 80.214 hd 59.79 37.334 nmcb 49.815 50.025 msd 73.73788 73.65656 table 2, c use of 1000 hash input to determine the average of the metrics metric rabbit-256 sha-256 bic 0.0004588 0.0004563 avalanche 127.872 80.39 hd 60.038 37.57 nmcb 49.948882 49.969921 msd 73.73166 73.72074 the performance and security of hash functions are evaluated based on two essential factors: confusion and diffusion. to clarify these concepts, confusion complicates the relationship between input and output, whilst diffusion distributes the effect of input on output. statistical tests measure the bits that change in the output when any modification occurs in the input, as approved by nist. the obtained results are used to demonstrate the efficiency and effectiveness of the hash functions, enabling various comparisons to be made. from tables 2a–2c, the avalanche effect and hd distribution of rabbit-256 are always better than those of sha-256 under any size (100, 500, 1000) of message digest. in crypto terms, a high avalanche effect indicates that a small number of input bits are spread over the output space, such that a single bit change in input causes approximately half of the bits to change output. whilst the above experiments put rabbit-256 against sha-256, researchers have considered other lightweight hash functions, as indicated in table 2. khalid jamal jadaa al-khwarizmi engineering journal, vol. 21, no.4, pp. 4564 (2025) 56 table 3, comparative features of rabbit-256 (this work) and lightweight hash functions from the literature metric (average) rabbit -256 (our work) blake 2s [aumass on et al., 2015] spongen t-128 [bogdanov et al., 2012] avalanche effect (%) ~58% ~54%– 56% ~48%–50% hd (bits) 58–60 averag e ~56 average ~32–34 average bit independen ce strong strong weak– moderate memory/po wer needs low moderate very low iot suitability excelle nt good excellent blockchain integration direct merkl e tree) direct rarely explored to create a reliable benchmarking comparison, the researchers do not adopt the exact values. the original values differ in the test dataset [42] [43], leading to the adoption of the average ranges that have been reported in the literature. table 3 provides a wider view by comparing rabbit-256, blake2s and spongent. rabbit-256 exhibits a stronger avalanche effect (about 58%) than spongent (about 48%–50%) and comes close to blake2s (about 54%–56%). it also reaches a higher hd (59–60 bits) than spongent. blake2s spreads data well but requires more memory. spongent uses less resources but does not separate data as well as blake2s. these results indicate that rabbit-256 achieves good balance and is fit for blockchainbased healthcare iot, where security and speed are important. moreover, well-balanced hd values imply that our proposed mrhb scheme is slightly independent, eliminating the possibility of an adversary guessing the relationships between input and output. in the health domain, such gcs directly translate into enhanced security for electronic health records and iot sensor data. for example, if one information changes slightly in a patient’s vital sign record, then this slight change will lead to a completely different hash, and the blockchain transaction will immediately go awry. determining if data were altered, which is an exceedingly important detail for tracking compliance with the rules imposed by the health insurance portability and accountability act (hipaa) and the general data protection regulation (gdpr), will be difficult. in addition, no rabbit256 slowdown is observed on larger sets (500– 1000 blocks), enabling rabbit-256 to handle the high volume of data traffic from a busy hospital and real-time iot data flows. that is, rabbit-256 has more benefits to offer than the sha-2 family, and the difference frequently matters in the real world. rabbit-256 provides a lighter but more secure method of hashing data; therefore, it is applicable to securing blockchain systems in healthcare. the next subsection explains the key metrics employed for the evaluation, as follows. 6.1. bit independence criterion (bic) analysis in the hash function, we can evaluate the independence of output bits with bic. the more robust the bic, the more challenging controlling and forecasting its product will be. attacker attempts to forge and manipulate hash values become harder. figures 8a–8c compare the proposed hashing method with sha-256 in terms of bic values. the graph shows the bic values of the proposed method and sha-256 when hashing 100/500/1000 length strings. comparing the bic results of rabbit-256 and sha-256, as presented in tables 2a–2c and figures 8a–8c, both algorithms generally have high bic values, indicating that their output bits are independent and unpredictable. however, some results indicate that the bic values for sha-256 are slightly higher in certain cases compared with the rabbit-256 results. this discrepancy suggests that rabbit-256 and sha256 may be more difficult for attacks that use correlations between output bits. khalid jamal jadaa al-khwarizmi engineering journal, vol. 21, no.4, pp. 4564 (2025) 57 fig. 8. a. bic values for the [rabbit-256, sha-256] case study [100] fig. 8. b. bic values for the [rabbit-256, sha-256] case study [500] fig. 8. c. bic values for the [rabbit-256, sha-256] case study [1000] 6.2. avalanche metrics analysis the ‘avalanche effect’ in hash functions is a wellknown phenomenon in cryptography. it can be summarised as follows: when a single bit of the input is flipped, an extremely large change occurs in the output hash value. this phenomenon can be quantified by calculating the percentage of bits changed in the output of two input that differ by 1 bit. in hash functions, when the value of the avalanche effect is close to 50%, which is the highest value, the case is considered optimal. the following well-known equation, called the standard percentage calculation, is utilised to find the measure: 𝐷 = 𝑋 𝑌 ∗ 100%, …(2) where d represents the avalanche effect, x represents the number of modified bits in the resulting hash value, and y represents the total number of bits in the hash value. as mentioned previously, the avalanche effect becomes more important for a stronger hash function, and vice versa. this condition makes constructing two messages that hash to the same value virtually impossible for an attacker. when comparing the avalanche effect measures of the modified rabbit-256 and sha-256, we can see that for a bit change probability, the modified rabbit-256 offers a 58% average bit change rate compared with up to 50% average bit change rate for sha-256. this result implies that the modified rabbit-256 algorithm exhibits better avalanche effect, i.e. any slight modification on the input will cause a major change in the output, as indicated in tables 2a–2c and figures 9a–9c. fig. 9. a. calculation avalanche metrics for the [rabbit-256, sha-2056] case study [100] khalid jamal jadaa al-khwarizmi engineering journal, vol. 21, no.4, pp. 4564 (2025) 58 fig. 9. b. calculation avalanche metrics for the [rabbit-256, sha-2056] case study [500] fig. 9. c. calculation avalanche metrics for the [rabbit-256, sha-2056] case study [1000] 6.3. hd metrics analysis hd indicates the similarity between two hash values by computing the number of positions at which their respective symbols are different. it determines the similarity between the two input by comparing their hashes. a distance with a low hamming value indicates that the two items are similar, whereas a large distance indicates high dissimilarity. this metric is useful in applications such as near-duplicate detection, fuzzy matching or similarity analysis amongst large-scale datasets. hd between two strings of equal length can be calculated using the following equation: 𝑑𝐻(𝐴, 𝐵) = ∑ (𝑎𝑖 ≠ 𝑏𝑖 𝑛 𝑖=1 ), …(3) where 𝑑𝐻(𝐴, 𝐵) indicates hd between strings a and b, ∑ .𝑛 𝑖=1 indicates the sum of the differences between corresponding symbols in the two strings, from 𝑖 = 1 to 𝑖 = 𝑛, where n is the length of the strings; 𝑎𝑖 and 𝑏𝑖 are the symbols at position i in strings a and b, respectively; and ≠ indicates inequality, such that the sum is only incremented when 𝑎𝑖and 𝑏𝑖 are different. fig. 10. a. calculation of hd in the [rabbit-256, sha-256] case study [100, 4950] fig. 10. b. calculation of hd in the [rabbit-256, sha-256] case study [500, 124750] fig. 10. c. calculation of hd in the [rabbit-256, sha-256] case study [1000, 499500] comparing the hd results of the modified rabbit-256 and sha-256, we can see that the modified rabbit-256 output has a higher average hd than the sha-256 output. this result indicates khalid jamal jadaa al-khwarizmi engineering journal, vol. 21, no.4, pp. 4564 (2025) 59 that the modified rabbit-256 algorithm produces output that is more different from each other than the output of sha-256, as presented in tables 2a–2c and figures 10a–10c. 6.4. analysis of the number of mean changed bits (nmcb) nmcb analysis evaluates cryptographic hash functions by measuring the average number of bits that change the hash value when a single bit is altered in the input. it assesses the avalanche effect, where a slight change in input results in a significant change in output. 𝑁𝑀𝐶𝐵 = 1 𝑁 ∗ ∑ (|𝑥𝑖 − 𝑦𝑖|)𝑛 𝑖=1 , …(4) where n is the total number of bits in the two binary sequences being compared, 𝑥𝑖and 𝑦 𝑖 are the corresponding bits in the two binary sequences and ∑ .𝑛 𝑖=1 the sum of the absolute differences between each corresponding bit in the two binary sequences is denoted. fig. 11. a. percentage of mean changed bits in the [rabbit-256, sha-256] case study [100] fig. 11. b. percentage of mean changed bits in the [rabbit-256, sha-256] case study [500] fig. 11. c. percentage of mean changed bits in the [rabbit-256, sha-256] case study [1000] by comparing the obtained results, we determine that the modified rabbit-256 algorithm is superior because it provides a result of 50.366% in terms of nmcb, whilst the result of sha-256 does not exceed 49.853%. the significance of this result is twofold: a minute modification to the input will exert several effects on the output hash. this result is a clear sign that the behaviour of the modified rabbit-256 algorithm depends more strongly on its input than that of sha-256. the two algorithms can be compared in terms of strength and security by using the hd shown in figures 11a–ac. tables 2a–2c present the comparison results between the modified rabbit-256 and sha256. 6.5. msd the quality of cryptographic hash functions is assessed by adopting a statistical technique that measures the difference between the average hd of all possible pairs of hash values and the expected value of hd under a uniform distribution. the mean µ and standard deviation σ of a dataset is calculated by utilising the following equation: 𝜇 = 1 2 ∗ ∑ (𝑥𝑖)𝑛 𝑖=1 , …(5) where 𝑛 is the entire number of data points, and 𝑥𝑖 denotes individual data points. 𝜎 = √(( 1 𝑛 ) ∗ ∑ (𝑥𝑖 − 𝜇)2)𝑛 𝑖=1 , …(6) where (sqrt) represents the square root function, and (𝑥𝑖 − 𝜇)2 represents the squared deviation of each data point from the mean. khalid jamal jadaa al-khwarizmi engineering journal, vol. 21, no.4, pp. 4564 (2025) 60 fig. 12. a. standard deviation of the changed bit number in the [rabbit-256, sha-256] case study [100] fig. 12. b. standard deviation of the changed bit number in the [rabbit-256, sha-256] case study [500] fig. 12. c. standard deviation of the changed bit number in the [rabbit-256, sha-256] case study [1000] for the modified rabbit-256, msd = 1.635, and the values of the hash output are considered relatively stable if most of their differences from the mean are less than 1.635. the msd for sha-256 is 2.309, over the value for sha-1. that is, most hash output values are close to 2.309 of the mean, as shown in figures 12a–12c. when msd is smaller, the dataset is more uniform and predictable. meanwhile, a higher msd indicates more variability and less predictability. expanding to what these outcomes mean in practice for healthcare iot (latency, data transfer, battery lifetime), the enhancements observed in the avalanche effect, hd and msd exert a direct effect on iot-based healthcare systems. a stronger avalanche property indicates less likelihood of differential attacks, such that even slight changes in the output values from a medical sensor (e.g. heart rate or glucose level) generate unpredictable hash values. this condition increases data integrity when transferring and archiving. trending systemwise, rabbit-256 outperforms sha-256 in terms of computational overhead, leading to reduced delay when providing security for fast iot streams, e.g. continuous patient surveillance. the minimisation of delay is expected to lessen delays for queueing construction and verification, making real-time clinical decision-making more realistic. moreover, lower computation per hash leads to less power consumption for on-device battery life against more computationally expensive approaches. this condition is particularly important for wearable or implantable sensors that need to continue to work well over a long period without frequent charging/replacement. an efficient hashing technique minimises intermediate exchanges within a blockchain, and thus, data transfer speed and the maximum scalability of healthcare data networks become faster/larger. introducing mrhb into the system of iotbased healthcare will be a huge attempt to focus on efficiency and resource-saving. however, following regulations remains important. mrhb must be compliant with regulations, such as those of hipaa and gdpr. these policies are in place to safeguard the security of patients’ confidential information (confidentiality, integrity and availability). these rules are enforced by mrhb with reliance on an inspection programme that verifies integrity. it employs top avalanche and diffusion mechanisms for realising attempts to modify medical information. it also makes rabbit256 a frugal solution, consistent with the policy protected by gdpr of ‘data protection by design and by default’. such construction can achieve secure hashing for low-powered or slow iot-based medical devices, but with reduced energy consumption and delay. in an hipaa-compliant system, mrhb works with blockchain-based electronic health records to help generate tamperproof patient records and audit logs. in addition to these standards, mrhb goes well beyond mere good cryptography, indicating that it can preserve khalid jamal jadaa al-khwarizmi engineering journal, vol. 21, no.4, pp. 4564 (2025) 61 the privacy of patients and be trusted in real-life healthcare operations. 7. conclusions in accordance with the result analysis, the rabbit‐ 256‐based optimisation of blockchain hashing for healthcare data security is a promising method. to our knowledge, the proposed algorithm is one of the first to combine the rabbit-256 stream cipher and the sha-256 hash function. the achieved entropy and randomness provide resistance against attacks and exhibit better security margin than competing ciphers. the cited results indicate that the proposed rabbit-256-based algorithm has sufficient strength and computational efficiency 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( 2025) 45-64، صفحة 4، العدد21مجلة الخوارزمي الهندسية المجلد خالد جمال جداع 64 ألنترنت االشياء منة في بيانات الرعاية الصحية لتجزئة البلوكتشين األ rabbit-256تحسين 4لطيفة منيرة قمرالدين ،3 وليد نوري حسين ،2 ايمن مظهر بدر ،*1عخالد جمال جدا الى، العراق يقسم هندسة الحاسوب، كلية الهندسة، جامعة ديالى، د 1 كلية الطب، جامعة ديالى، ديالى، العراق 2 كلية طب الزهراء، جامعة البصرة، البصرة، العراق 3 قسم هندسة الحاسوب و االتصاالت، جامعة برليس الماليزية، برليس، ماليزيا 4 ، برليس، ماليزيا(ceastechمركز التميز لتكنولوجيا االستشعار المتقدمة ) 4 khalid.jamal.jadaa@gmailcom :البريد االلكتروني * المستخلص لدوال التجزئة ادت الى محدودية استخدامها تقيات البلوكتشين اصبحت اداة مطروحة لتأمين سجالت الرعاية الصحية، لكن بسبب التكلفة الحسابية العالية و هي عبارة عن دالة محدثة و مشتقة من تشفير (rabbit-256في اغلب سناريوهات انترنت االشياء. و لحل هذه المشكلة تقترح هذه الورقة البحثية دالة ) ن ( للتحول الى دالة تجزئة خفيفة الوزن لتكون متناسبة و مخصصة الى انظمة الراعاية الصحية القائمة على تقنية البلوكتشين. وهي عبارة عrabbitتدفق ) merkleر ُمحّسن، وقدرة على العمل في )شفرة تشفير خفيفة الوزن ُمقنّعة بشكل رقيق، ُحّولت إلى دالة تجزئة ذات خصائص انتشار قوية، وسلوك انهيا tree.) تم عمل مقارنة هذه الدراسة الُمقترحة بخوارزميةsha-256 1000و 500و 100باستخدام مقاييس تشفير قياسية، ومشغالت شبكة تتكون من يوفر هامش أمان أقوى وتعقيدًا حسابيًا أقل، (rabbit-256)االنحراف المعياري. تُظهر النتائج أن ُمدخل من حيث تأثير االنهيار، ومسافة هامينغ، ومتوسط الطريق rabbit-256وبينما يُجرى العمل الحالي في المحاكاة، يُمهد مما يُظهر أنه حل فعال ألجهزة إنترنت األشياء المحدودة مع الحفاظ على متانة التشفير. وفي المستقبل، لتحقيق أمن سجالت الصحة اإللكترونية وبيانات أجهزة االستشعار الطبية في إنترنت األشياء والخدمات السريرية على تقنية البلوك تشين. قانون مثل الصحية الرعاية لوائح مع يتوافق بما والتكامل الطاقة، استهالك وتحسين األجهزة، تطبيقات تطوير على والمساءلة سنعمل الصحي التأمين (hipaa( والالئحة العامة لحماية البيانات )gdpr.) mailto:khalid.jamal.jadaa@gmailcom this is an open access article under the cc by license : al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 21, no. 3, september, (2025), pp. 6675 studying the effect of rotor’s coefficients on a y-shaped tri-copter abdullah mohammed yahia1*, ahmed alkamchi2 and ergun erçelebi3 1,2 department of mechatronics, al-khwarizmi college of engineering, university of baghdad, baghdad, iraq 3 electrical and electronic department, college of engineering, gaziantep university, turkey *corresponding author’s email: abd.yahia2102m@kecbu.uobaghdad.iq (received 23 may 2024; revised 21 october 2024; accepted 28 december 2024; published 1 september 2025) https://doi.org/10.22153/kej.2025.12.002 abstract unmanned aerial vehicles (uavs) are small yet highly capable aircraft widely used in many applications. uav designs and shapes vary depending on their intended usage. tri-copters, known for their agility, have three propellers. however, one of their main challenges is yawing, which occurs when the uav rotates around its z-axis (yaw angle). this yawing issue is a result of the asymmetry in the number of propellers. unlike quadcopters, which have an even number of propellers, the aerodynamic drag torque produced by the tri-copter’s propellers’ does not cancel out. in this paper, a y-shaped tri-copter model is tested, modified and compared to address the yawing problem. aiming to mitigate yawing, two propellers are set to rotate clockwise, whilst the third propeller rotates clockwise. in the first configuration, the force coefficient is set equally for all propellers. in the second configuration, the force coefficient of the counter-clockwise rotating propeller is doubled. the uav model is controlled by six pids associated with feedback linearisation for both configurations—three pids for attitude control and three for altitude control. the pids are tuned using a genetic algorithm, and the system is simulated in matlab simulink. the proposed configuration demonstrates lower integral time absolute error (itae) values, indicating improved uav performance. the average itae values for the y-shaped model are 0.1553 for the first case and 0.1017 for the second case. the second case shows remarkable tracking in the desired output, with no violation of design limitations (servo angles and motor speeds). keywords: pid; genetic algorithm; uav; thrust-vectoring; feedback-linearisation. 1. introduction unmanned aerial vehicles (uavs) are small aircraft that can be controlled remotely or by an onboard navigation unit. uavs have a wide range of applications across various fields, leading to numerous configurations (including bi-copters, tricopters and quad-copters), each with different frame shapes and motor configurations [1]. bi-copters are amongst the simplest in terms of the number of actuators. they typically have only two to four actuators: two main propellers and one or two additional servo motors to control yaw and roll motions[2, 3]. the control systems of bi-copters are considered challenging due to the limited number of actuators, making them under-actuated. thus, bicopters are governed by a set of non-linear equations and generally offer less stability [4]. quad-copters are amongst the most reliable uavs, utilising four propellers (under-actuated)[5]. by adding two to four servo motors, these uavs can be fully actuated[6] or even over actuated[7], simplifying control. however, one of the main challenges for uavs is power consumption, which can limit their capabilities and flight time [8]. in contrast, tri-copters are known for their power efficiency because they use only three rotors [9]. aiming to enhance agility and manoeuvrability [10], a thrust-vectoring mechanism can be added. the main issue with tri-copters is yawing, which mailto:abd.yahia2102m@kecbu.uobaghdad.iq https://doi.org/10.22153/kej.2025.12.002 abdullah mohammed al-khwarizmi engineering journal, vol. 21, no.3, pp.6675 (2025) 67 arises from the asymmetry in rotor numbers and their rotational directions. with three rotors, the aerodynamic forces acting on the blades of each rotor do not cancel out, leading to yaw instability. this issue can be addressed by using coaxial rotors [11], implementing specific control strategies[12] or employing tiltable rotors[13]. tilt mechanisms can be integrated into different configurations to meet desired application demands, as shown in [14], [15] and [16]. for system control, various methods have been verified; for example, the linear quadratic regulator is used in [17], h-infinity is used in [18] and a proportional integral derivative (pid) is applied in [19]. the pid control, when associated with optimisation techniques to maximise system performance, can be a very practical approach to uav control [20]. various optimisation techniques, such as grey wolf optimisation, have been employed for this purpose [21]. 2. y tri-coper mathematical model in this section, the mathematical model of the uav is presented for two different motor configurations (two cases). the uav parameters are referenced from [22], as shown in table 1. table 1, uav parameters value description parameter 1.448 𝑘𝑔 uav mass 𝑚 0.33 𝑚 arm length 𝑎 0.1035 𝑘𝑔. 𝑚2 body inertia of x axis 𝛪𝑥𝑥 0.1003 𝑘𝑔. 𝑚2 body inertia of y axis 𝛪𝑦𝑦 0.1709 𝑘𝑔. 𝑚2 body inertia of z axis 𝛪𝑧𝑧 1.084 × 10−5 𝑘𝑔. 𝑚 force coefficient 𝑘𝑓 1.726 × 10−7 𝑘𝑔. 𝑚2 torque coefficient 𝑘𝑡 the primary model and dynamic equations are sourced from [23], along with the feedback linearisation equation, incorporating a modification to the original motor rotation directions. in both cases, the motor rotation directions are consistent: the front motors rotate clockwise, whilst the rear motor rotates counter-clockwise, as shown in figure 1. in this context, α represents the servo angle, with the subscripts referring to the corresponding arm (right [r], left [l] and back [l]), and ‘a’ denotes the arm length, which is equal for all arms. fig. 1. uav motor configuration the motor coefficients will only differ in the second case, where the back motor coefficients are doubled. when this modification is implemented, certain adjustments to the original model will be required, as shown below. 2.1. first case in this case, the force coefficient for all motors will remain the same. the only change will be the direction of the rear motor, which will affect the mathematical representation of the drag torque, as shown below: 𝜏𝑑1 = [ 0.866𝑘𝑡𝜔𝑚𝑟 2 𝑐𝑜𝑠(𝛼𝑟) − 0.866𝑘𝑡𝜔𝑚𝑙 2 𝑠𝑖𝑛(𝛼𝑙 ) −𝑘𝑡𝜔𝑚𝑟 2 𝑠𝑖𝑛(𝛼𝑟) + 0.5𝑘𝑡𝜔𝑚𝑙 2 𝑠𝑖𝑛(𝛼𝑙)−0.5𝑘𝑡𝜔𝑚𝑏 2 𝑠𝑖𝑛(𝛼𝑏) −𝑘𝑡𝜔𝑚𝑟 2 𝑐𝑜𝑠(𝛼𝑟) − 𝑘𝑡𝜔𝑚𝑙 2 𝑐𝑜𝑠(𝛼𝑙) + 𝑘𝑡𝜔𝑚𝑏 2 𝑐𝑜𝑠(𝛼𝑏 ) ] …(1) where 𝜏𝑑( ) is the drag torque for the corresponding case, 𝑘𝑡 is the torque coefficient, 𝛼( ) is the servo angle for the corresponding arm (b for back, r for right and l for left) and 𝜔( ) 2 is the squared angular velocity for the corresponding arm. 2.1. second case in this case, the drag torque will remain the same as in case one because the motor’s rotation directions are set identically. the only difference is that the torque coefficient for the back motor is doubled. cc w a a a abdullah mohammed al-khwarizmi engineering journal, vol. 21, no.3, pp.6675 (2025) 68 𝜏𝑑2 = [ 0.866𝑘𝑡𝜔𝑚𝑟 2 𝑐𝑜𝑠(𝛼𝑟) − 0.866𝑘𝑡𝜔𝑚𝑙 2 𝑠𝑖𝑛(𝛼𝑙 ) −𝑘𝑡𝜔𝑚𝑟 2 𝑠𝑖𝑛(𝛼𝑟) + 0.5𝑘𝑡𝜔𝑚𝑙 2 𝑠𝑖𝑛(𝛼𝑙) + 2(−0.5𝑘𝑡)𝜔𝑚𝑏 2 𝑠𝑖𝑛(𝛼𝑏) −𝑘𝑡𝜔𝑚𝑟 2 𝑐𝑜𝑠(𝛼𝑟) − 𝑘𝑡𝜔𝑚𝑙 2 𝑐𝑜𝑠(𝛼𝑙 ) + 2𝑘𝑡𝜔𝑚𝑏 2 𝑐𝑜𝑠(𝛼𝑏) ] …(2) by doubling the force coefficient, the force and torque equations are modified as shown below: 𝑓 = [ −0.866𝑘𝑓 𝜔𝑚𝑙 2 𝑠𝑖𝑛(𝛼𝑙) + 0.866(2𝑘𝑓)𝜔𝑚𝑏 2 𝑠𝑖𝑛(𝛼𝑏 ) 𝑘𝑓𝜔𝑚𝑟 2 𝑠𝑖𝑛(𝛼𝑟) + −0.5𝑘𝑓 𝜔𝑚𝑙 2 𝑠𝑖𝑛(𝛼𝑙) + 2(−0.5𝑘𝑓)𝜔𝑚𝑏 2 𝑠𝑖𝑛(𝛼𝑏) 𝑘𝑓𝜔𝑚𝑟 2 𝑐𝑜𝑠(𝛼𝑟) + 𝑘𝑓𝜔𝑚𝑙 2 𝑐𝑜𝑠(𝛼𝑙) + 2𝑘𝑓𝜔𝑚𝑏 2 𝑐𝑜𝑠(𝛼𝑏) ] …(3) 𝜏 = [− 0.866𝑘𝑓 𝜔𝑚𝑙 2 𝑐𝑜𝑠(𝛼𝑙) − 0.866(2𝑘𝑓)𝜔𝑚𝑏 2 𝑐𝑜𝑠(𝛼𝑏) 𝑘𝑓𝜔𝑚𝑟 2 𝑐𝑜𝑠(𝛼𝑟) + 0.5𝑘𝑓𝜔𝑚𝑙 2 𝑐𝑜𝑠(𝛼𝑙) + 2(0.5𝑘𝑓)𝜔𝑚𝑏 2 𝑐𝑜𝑠(𝛼𝑏 ) 𝑘𝑓𝜔𝑚𝑟 2 𝑠𝑖𝑛(𝛼𝑟) + 𝑘𝑓𝜔𝑚𝑙 2 𝑠𝑖𝑛(𝛼𝑙 ) + 2𝑘𝑓𝜔𝑚𝑏 2 𝑠𝑖𝑛(𝛼𝑏) ] …(4) where 𝑘𝑓 is the force coefficient, 𝑓 is the total force and 𝜏 is the total torque. 3. proposed controller the tri-rotor equations exhibit strong output coupling, necessitating the use of pid controllers in combination with feedback linearisation. as referenced in section 1, the feedback linearisation method is also adopted from previous work. a total of six pid controllers are used to control the uav: three for position control (x, y, z) and three for attitude control (, , ). this control approach remains the same for both cases, as shown in figure 2. fig. 2. system block diagram 3.1 proportional integral divertive controller (pid) after linearising the system, a linear pid controller can be applied. the pid controller is considered an optimal choice due to its simple implementation and high efficiency [24]. the standard pid formula used to compute the error signal is referenced from [25]. 𝑢(𝑡) = 𝐾𝑃𝑒(𝑡) + 𝐾𝐼 ∫ 𝑒(𝑡)𝑑𝑡 + 𝐾𝐷�̇�(𝑡) …(5) where 𝐾𝑃 is the proportional gain, 𝐾𝐼 is the integral gain, 𝐾𝐷 is the derivation gain and 𝑒(𝑡) represents the error signal. the system uses six pid controllers, divided between position and attitude control. each controller is separately tuned using the genetic algorithm (ga) optimisation method, with the integral time absolute error (itae) used as the cost function. 3.2 pid tunning the pids are tuned using the ga, a method introduced by john holland in 1975 [26]. based on the concepts of evolution, ga operate by choosing the most adapted individuals (elite members) form a population to reproduce and generate a new generation. this process involves selecting individuals, evaluating their performance, combining their solutions through genetic crossover, applying random mutations and modifying the population with the best-performing solutions. this approach, which mirrors the concept of natural selection, is effective for minimising specific cost functions (in this case, the system error). the ga is used to tune the pid controllers for both cases, implemented using a built-in matlab function. the selected cost function for evaluating performance is the itae [27]. ∫ 𝑡|𝑒(𝑡)|𝑑𝑡 ∞ 0 …(6) figure 3 shows the genetic algorithm flow chart. abdullah mohammed al-khwarizmi engineering journal, vol. 21, no.3, pp.6675 (2025) 69 genetic algorithm working steps flow chartfig. 3. [28] 4. simulation results the pid parameters are tuned by setting the desired outputs for position and altitude to 1 m and 10deg for attitude. in this section, the system responses for both cases will be represented, along with their corresponding itea values and a simulated flight scenario. each case will be evaluated based on its tracking performance and control efficiency. 4.1. first case the pid gain and the itae values for the first case are shown in table 2. table 2 pid parameters, first case itea kd ki kp parameter 0.0421 3.63 0.397 14.64 phi 0.0241 4.15 0.033 19.48 theta 0.0252 4.72 0.03 19.77 psi 0.3591 4.21 16.06 18.58 x 0.3605 4.02 14.49 19.85 y 0.1211 4.58 0.026 17.9 z figures 4 and 5 show the tuning responses for the altitude and attitude, respectively, during the tuning process for the first case. the performance metrics of case one are as follows: altitude settle time: (1.7 s), x overshoot: (38%), y overshoot: (37%) and z overshoot: (10%). for case one, attitude settle time is (2.1 s), phi overshoot is 17%, theta overshoot is 16 % and psi overshoot is 11%. fig. 4. uav altitude response for the first case fig. 5. uav attitude response for the first case 4.2. second case the second case showed lower itae values after doubling the back motor’s coefficients, as shown in table 3. table 3 pid parameters, second case itea kd ki kp parameter 0.0307 4.97 0.595 19.98 phi 0.0167 5.67 0.015 19.26 theta 0.0368 3.7 0.403 19.63 psi 0.0889 5.83 0.018 19.82 x 0.3447 4.45 18.03 18.57 y 0.0924 5.46 0.016 19.81 z figures 6 and 7 illustrate the tuning responses for altitude and attitude, respectively, during the tuning process of the second case. the performance metrics of case two are as follows: altitude settle time: (1.7 s), x overshoot: (3%), y overshoot: (40%) and z overshoot: (5%). for case two, attitude abdullah mohammed al-khwarizmi engineering journal, vol. 21, no.3, pp.6675 (2025) 70 settle time is 2 s, phi overshoot is 10%), theta overshoot is 11% and psi overshoot is 22%. fig. 6. uav altitude response for the first case fig. 7. uav attitude response for the first case the second case demonstrated lower itae values; thus, a flight scenario was then applied to further evaluate the uav performance. the uav is initially positioned at (0,1,0), ascending vertically and then follows a spiral shape. this approach is achieved using a circular equation for the x and y coordinates, a ramp function for the z coordinate and setting all attitude variables to zero. figure 8 illustrates the flight scenario. fig. 8. uav helical flight scenario the uav smoothly tracked due to its enhanced manoeuvrability provided by the thrust vectoring mechanism. the motor forces remained balance due to the back motor having increased force and torque coefficients. aiming to thoroughly evaluate the system’s performance, the responses of altitude, attitude, motor speeds and servo angles were captured during the flight. figure 9 shows the altitude response. fig. 9. uav helical flight scenario altitude response the altitude responses closely followed the desired trajectory without any issues, demonstrating the uav’s effective manoeuvrability. figure 10 displays the attitude response. abdullah mohammed al-khwarizmi engineering journal, vol. 21, no.3, pp.6675 (2025) 71 fig. 10. uav helical flight scenario attitude response the attitude responses remained zero throughout the entire flight, indicating that the uav maintained good balance. figures 11 and 12 show the responses of the motors and servo motors, respectively. the motor speed limits are set between 0 and 3600 rpm, whilst the servo angle limits range from −90° to 90°. fig. 11. uav helical flight scenario motors response fig. 12. uav helical flight scenario servo motors response the motors speed values increased as the uav took off, then settled at a specific value and did not exceed the design boundaries. the back motor shows lower speed values because it has larger coefficients. the responses of the servo angles change continuously to maintain the uav on the desired path. the second case showed lower itae values; therefore, a disturbance test and an uncertainty test were then applied to further evaluate the uav’s performance. the uncertainty test responses and itae values after changing the mass to 1.8 kg and the arm length to 0.2 m are shown in table 4. table 4 uncertainty itae values, second case itea uncertainty parameter 0.03 phi 0.016 theta 0.035 psi 0.09 x 0.347 y 0.093 z figure 13 shows the uncertainty test responses for altitude and attitude. all responses stabilise within approximately 2 s. (a) (b) fig. 13. uncertainty altitude & attitude responses for y-model: (a) altitude responses, (b) attitude responses figure 14 shows an impulse disturbance applied along the z-axis. the disturbance has a magnitude of 5 n and lasts for 0.25 s, starting at t = 4 s. the system regains stability approximately 1 s after the disturbance ends. abdullah mohammed al-khwarizmi engineering journal, vol. 21, no.3, pp.6675 (2025) 72 fig. 14. disturbance on z axis figure 15 shows disturbances on the phi rotation angle. the disturbance has a magnitude of 10 n.m. this disturbance starts at t = 2.5 s and ends at t = 2.75 s. the system regains stability approximately 2 s after the disturbance ends. fig. 15. disturbance on phi 5. conclusion this research aims to study the effects of rotor coefficients on uav performance. a previously developed model is modified by changing the rotation direction of the rotors: the front two propellers are set to rotate clockwise, and the back propeller rotates counter-clockwise. the modified model is then divided into two cases. case one includes the model with the changed rotation direction and no further modifications, whilst case two involves doubling the coefficients of the back motor. both cases are linearised using feedback linearisation to address the output coupling problem and are controlled by six pid controllers. the pid controllers are tuned using a ga, with the itae as the cost function. the average itae values for the yshaped model are 0.1553 and 0.1017 for cases one and two, respectively. case two showed improved tracking of the desired output in the applied scenario without exceeding design limitations (servo angles and motor speeds). aiming to further investigate the effects of rotor coefficients, implementation on a model without thrust vectoring is recommended. notations x xaxis, m y yaxis, m z f zaxis, m force, n a length, m kf force coefficient, 𝑁. 𝑠2 kt torque coefficient, 𝑁. 𝑚. 𝑠2 m mass, kg ixx body inertia of x-axis, 𝑘𝑔. 𝑚2 iyy body inertia of y-axis, 𝑘𝑔. 𝑚2 izz body inertia, of z-axis 𝑘𝑔. 𝑚2 e error kp proportional pid gain ki integral pid gain kd derivative pid gain greek symbols  servo angle, deg  roll angle, deg  pitch angle, deg 𝜓 yaw angle, deg  torque, 𝑁. 𝑚  angular velocity, rpm references [1] m. h. sabour, p. jafary, and s. nematiyan, “applications and classifications of unmanned aerial vehicles: a literature review with focus on multi-rotors,” the aeronautical journal, vol. 127, no. 1309, pp. 466–490, 2023, doi: 10.1017/aer.2022.75. 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( 2025) 66-75، صفحة 3، العدد21مجلة الخوارزمي الهندسية المجلد عبد هللا محمد يحيى 75 yدراسة تأثير معامالت الدوار على مروحية ثالثية الشكل على شكل حرف 3اركون ارچلبي 2احمد محروس راغب* *1عبد هللا محمد يحيى العراق بغداد، قسم هندسة الميكاترونكس، كلية الهندسة الخوارزمي، جامعة بغداد، 1،2 يا ترك ، جامعة غازي عنتاب ، قسم الهندسة الكهربائية وااللكترونية 3 abd.yahia2102m@kecbu.uobaghdad.edu.iqالبريد االلكتروني: * لمستخلص ا وتستخدم على نطاق واسع في العديد من التطبيقات. هناك العديد من التصاميم بكفاءة الطائرات بدون طيار هي طائرات صغيرة ولكنها قادرة على العمل ألنها تحتوي على ثالثة ؛ واألشكال للطائرات بدون طيار اعتمادًا على استخدامها. تعد الطائرات ثالثية المراوح واحدة من أكثر الطائرات بدون طيار رشاقة (. يحدث ذلك بسبب عراج)زاوية االن zالطائرة بدون طيار وهو دوران الطائرة بدون طيار حول محورها عراجمراوح فقط. ومع ذلك، فإن إحدى مشاكلها هي ان رات المراوح كما هو الحال في طائرة رباعية المراوح وح. بمعنى آخر، لن يتم إلغاء عزم السحب الناتج عن الديناميكا الهوائية لشفاالمر عدادعدم التماثل في أ يتم و، عراج لتقليل تأثير مشكلة االن ؛ وتعديله ومقارنته yتم اختبار نموذج طائرة ثالثية المراوح على شكل حرف عمل)عدد زوجي من المراوح(. في هذه ال . ى األول حالةوح في الضبط مروحتين في اتجاه عقارب الساعة، بينما يتم ضبط المروحة الثالثة في االتجاه المعاكس. يتم ضبط معامل القوة بالتساوي لجميع المرا يتم التحكم في النموذج من خالل ستة معّرفات ف. ةالثاني حالةثم يتم مضاعفة معامل القوة للمروحة الواحدة التي تدور في اتجاه عكس اتجاه عقارب الساعة لل pid وثالثة لالرتفاع. يتم ضبط معّرفات ، كوينين ثالثة للموقفمرتبطة بالخطية الراجعة لكال التpid باستخدام خوارزمية وراثية ويتم محاكاة النظام في matlab simulink يظهر التكوين المقترح قيم .itae أقل )خطأ مطلق زمني متكامل( مما يشير إلى أداء أفضل للطائرات بدون طيار. متوسط قيم itae للنموذج على شكلy ( للحالة األولى0.1553هو )، ( للحالة الثانية. أظهرت الحالة الثانية تتبعًا كبيًرا لإلخراج المطلوب في السيناريو 0.1017و ) المطبق ولم تتجاوز قيود التصميم )زوايا المؤازرة وسرعات المحركات(. al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 5, no. 3, pp 28 37 (2009) time prediction of dynamic behavior of glass fiber reinforced polyester composites subjected to fluctuating varied temperatures louay s. yousuf department of mechanical engineering/ college of engineering/ university of baghdad louaysabah79@yahoo.com (received 2 april 2009; accepted 5 august 2009) abstract the reduction of vibration properties for composite material (woven roving e-glass fiber plies in thermosetting polyester matrix) is investigated at the prediction time under varied combined temperatures (60 to -15 ) using three types of boundary conditions like (cfcf, cccf, and cfcc). the vibration properties are the amplitude, natural frequency, dynamic elastic moduli (young modulus in x, y directions and shear modulus in 1, 2 plane) and damping factor. the natural frequency of a system is a function of its elastic properties, dimensions, and mass. the woven roving glass fiber has been especially engineered for polymer reinforcement; but the unsaturated thermosetting polyester is widely used, offering a good balance of vibration properties at moderate or ambient temperatures, and also at relatively low cost. the mismatch between matrix and fiber yarns gives a predominant role for the fiber's mechanics where the matrix is the area where most damage mechanisms develop. the free vibration test was carried out for (5, 10, 15, 20, 25, 30) minutes. the composite plate was exposed to (75 ) of thermal gradient for ten times in various times at different stages. the results were classified into experimental and finite element using software ansys ver. 9. keywords: time prediction, composite material, varied temperatures 1. introduction composites are used almost in all engineering fields especially in aerospace and defense industries these days and their applications are growing very rapidly. the simulation of a reduction in the fundamental frequency and of damping with an increase in the percentage of uniform moisture and temperature (hygro-thermal effect) at ( are accomplished for material properties (extensional and flexural stiffness) of graphite/ epoxy composite beams, plates, and shells with respect to ply angles, fiber volume ratio, and temperature using finite element discretization, [1, 2, 3]. random response in using shape memory alloy hybrid composite can be reduced greatly when the plates are subjected to a steady state constant temperature and uniform sound pressure with the aiding of nonlinear finite element model, [4]. the dynamic load factor of simply supported glass/epoxy composite beams increase due to moving loads (forced vibration) and hygro-thermal effects because of degrading the material stiffness properties of the matrix by varying the fiber volume fraction and the fiber orientation of the angle plies in the laminate, [5]. a damping monitoring method is used to measure, calculate, and investigate the natural frequency, elastic modulus in (x, y) directions and the damping factor for polyethylene fiber composite beam under varied temperature (-10 to 60 ) for free-free boundary conditions, but both natural frequency and elastic modulus decreased with the increase of temperature adversely for damping factor, [6]. a shooting method is applied numerically to calculate the first three frequencies of orthotropic circular plate due to uniform temperature rise and found that the three lowest frequencies of the buckled plate decrease with an increase in the temperature using clamped or simply supported boundary conditions moving in the radial direction, [7]. on the other mailto:louaysabah79@yahoo.com louay s. yousuf al-khwarizmi engineering journal, vol. 5, no. 3, pp 28 37 (2009) 29 hand, ultrasonic oscillator technique was used to generate ultrasonic stress waves at 80 and 150 khz (forced frequency) to measure the mechanical damping (in longitudinal vibration mode) and temperature dependence of dynamic modulus in the longitudinal, transverse fiber direction. ramadan j. mustafa [8] suggested that the dynamic modulus decreases with the increase of temperature from room temperature to 450 . the present investigation aim is to predict the perfect time that participates in the reduction of natural frequency, dynamic elastic moduli and in the increase of the damping factor under varied temperatures. 2. experimental setup and procedure 2.1 composite laminate fabrication fabrication of composite laminates was conducted in a mold consisting of (24 cm * 24 cm) aluminum with two x-ray photo sheets to avoid abrasive and to insure the flattening of the specimen surface. the x-ray photo sheet, which was first placed on the bottom of the aluminum mold, was wet with the catalyzed polyester resin before the first ply was placed on it. more catalyzed resin was applied to the first ply with brush until it was thoroughly wet. following this, the remaining plies were placed in the mold following the same sequence. the mold left for one day with sufficient pressure (2604.1667 ) to get rid of the excess resin and entrapped air bubbles and to remove the composite plate from the mold. the assembly was heated to (70 ) in an oven at (3 hours) curing time to complete cross-linking. the fiber volume fraction was determined for the glass fiber composites from the following relationship, [9]: m f f      * 1 1 1    …(1) cm f m  …(2) 2.2 vibration measurement the fundamental natural frequency for the first mode can be estimated by using the rubber tip hammer test; but it can be calculated before and after exposure to combined temperatures to show how they have affect on the composite material free vibration property reduction. there are many parts that are needed in this test are as follows: (1) frame fixture. (2) the rubber tip hammer. (3) winscope programming. (4) wave transporter. the plate has the dimensions (a = 0.3 m, b = 0.24 m, h = 0.0016 m, .%076.25 vol ). the specimen was treated in a thermal box environment at (60 ) temperature for (5 minutes) and then was immediately exposed at (-15 ) temperature of the same period of time for one cycle of ten cycles [10]. the heating temperature (60 ) was obtained using a heater (400w) made from ceramic material. the heater was in contact with electrical contactor and mesh with thermal controller, adversely the cooling temperature (15 ) obtained from use the refrigerant ferion gas (r-134a) flows from solenoid valve. solenoid valve contacts with gas bottle and when temperature reaches above (-15 ) the solenoid gate valve must be opened to compensate gas flow to the plate; but if the plate reaches the steady state setting temperature (-15 ) the solenoid gate valve closes. after applying fluctuating temperatures, the elastic moduli have been changed due to these loadings causing a change in bending stiffness material and that affects the values of vibration properties for different conditioning time intervals. a free vibration test has been achieved with inconstant impact load which is applied to induce vibration using a spherical rubber ball hammer. to measure the amplitude’s magnitudes, wave transporters (one kind of many accelerometers kinds) are placed on the mid-point of the specimen to convert the vibration response to the computer using linking wire. a winscope programming with a bandwidth limitation between (20 hz to 20 khz) that picks up or records the frequency wave of the composite plate and gives all the vibration properties was needed. the operation sequence of the present paper can be illustrated in fig. (1a, b). after measuring the amplitudes of two successive sinusoidal waves and damped natural frequency from winscope programming, the value of natural frequency can be found from the following relationships, [11]: 2 1 **2 2 1 ln      x x …(3) louay s. yousuf al-khwarizmi engineering journal, vol. 5, no. 3, pp 28 37 (2009) 30 2 1*   nd …(4) 21 * *100..      eop … (5) fig.2 shows the sequence of the edged boundary conditions and can be named as: cfcf which means: edge (3) fixed, edge (2) free, edge (1) fixed, edge (4) free. cccf which means: edge (3) fixed, edge (2) fixed, edge (1) fixed, edge (4) free. cfcc which means: edge (3) fixed, edge (2) free, edge (1) fixed, edge (4) fixed. fig.1a. block diagram of combined temperature loading sequence operation. fig.1b. measurement of natural frequency due to free vibration test. fig.2. sequence edges of boundary conditions. 2.3 dynamic elastic moduli measurement the tension moduli, for the e-glass and polyester matrix were determined by taking the average young's modulus of three specimens with loading (10 kn). the machine that made a tensile and compression testing device was of type instron, model 1195, at a speed of (1mm/min). the test specimens of the composites were prepared according to the (astm d 3039) standard. the instron's plotter draw the loaddeflection curves. the stress can be calculated from the equation ( ), where (p) and (a) represent the load taken from the curve, and the instantaneous cross sectional area respectively. before and after applying combined loading temperatures, the elastic moduli have changed. as an example, when the composite specimen is exposed to heating (60 ) for (5 minutes) and they immediately to cooling (-15 ) for (5 minutes) with ten times repeated of cycle number one alone then the plate can be cut into tensile astm dimensions and begin the tension test with instron plotter device. this operation is repeated each time for (10, 15, 20, 25, and 30) minutes to obtain the dynamic elastic moduli. the shear modulus for composite plate can be found from the following formula, [12]: ) 1 12 *2 2 1 1 14 ( 1 12 eeexe g    …(6) the specimen geometry used for both tension and shear moduli test can be shown in fig. 3. louay s. yousuf al-khwarizmi engineering journal, vol. 5, no. 3, pp 28 37 (2009) 31 fig. 3. tensile test specimen. 3. numerical procedure table 1, mechanical property of composite laminate before combined temperatures effect. (gpa.) 19.933 19.933 3.0896 0.3835 0.32 0.32 1.07675 0.681 0.681 1464.18 modal analysis is carried out with ansys ver. 9 finite element software. the linear elastic orthotropic model is used to investigate the cloth composite laminated plate. for this problem, the (solid45) element is used. this element is used for the three-dimensional modeling of solid structure and is defined by eight nodes. it has three degrees of freedom at each node: translations in the nodal x, y, and z directions. mechanical properties of the composite plate are taken from table 1. to determine the natural frequencies, modal analysis is carried out using the subspace method with ansys in cfcf, cccf, and cfcc boundary conditions. after load applying, the mechanical properties varied with each time with intervals as mentioned above. from the experimental work that can be taken the change in elastic mechanical properties due to temperature loadings effect might be entered instead of the mechanical properties before this applying the loadings listed in table 1 for the same ansys program, and that gives different values for natural frequency according to its conditioning time. the same ansys program is repeated each time for (5, 10, 15, 20, 25, and 30) minutes because the elastic moduli have been changed. 4. results and discussion in general the logarithmic decrement, damping factor, and damped forced frequency are given in table 2 using cfcf, cccf, and cfcc boundary conditions. in table 2 the damped forced frequency is the same for all boundary conditions because the damping factor is nearly constant. the constant damping factor refers to the stiffness and mass properties of composite plate before applying temperature loadings and that does not change with the variation of boundary conditions because the inverse of critical camping coefficient is still constant. table 2, vibration parameters before combined temperatures effects. (hz) boundary conditions 64.6 0.10963 0.6931 cfcf 64.6 0.1617 1.0296 cccf 64.6 0.1096 0.6931 cfcc table 3 gives the comparison between modal experimental and numerical analysis before temperatures effect using different boundary conditions. it can be noticed that the clamed boundary conditions from all plate edges are not take in our account because there is something wrong in the nature of fixture. one-third of the plate length must be fixed with bolts from every directions. table 3, experimental and numerical comparison before temperatures effect. fundamental natural frequency (hz) boundary conditions experimental work sysna percentage error cfcf 64.9917 69.914 7.0405% cccf 65.4616 71.63 8.6114% cfcc 64.9918 71.543 9.15701% louay s. yousuf al-khwarizmi engineering journal, vol. 5, no. 3, pp 28 37 (2009) 32 table 4 shows the variation of dynamic mechanical properties as a result of temperatures effect with different conditioning time. all properties varied sinusoid ally. it can be noticed that the young modulus in (x, y) directions is the same because the distance between fiber yarn is the same in (x, y) directions, but the perpendicular effect gives a different young modulus in zdirection. the shear modulus in 23, 13 planes is the same because the thickness along z-direction for all points of the specimen is the same; adversely, the shear modulus in 12 plane is different since the dimension in (x, y) directions is larger than the dimension in z-direction. table 4, dynamic mechanical property of composite laminate after combined temperatures effect. time (min) 5 10 15 20 25 30 (gpa.) 19.363 21.41 17.434 17.76 20.102 23.548 19.363 21.41 17.434 17.76 20.102 23.548 3.001 3.31 2.702 2.752 3.115 3.649 0.372 0.411 0.335 0.341 0.386 0.453 0.31 0.343 0.279 0.285 0.322 0.378 0.31 0.343 0.279 0.285 0.322 0.378 1.045 1.156 0.941 0.959 1.085 1.272 0.661 0.731 0.595 0.606 0.686 0.804 0.661 0.731 0.595 0.606 0.686 0.804 table 5, experimental and numerical comparison after temperatures effect. fundamental natural frequency (hz) boundary conditions cfcf cccf time (min) experimental ansys error experimental ansys error 5 67.914 73.386 7.4% 69.581 74.885 7.1% 10 75.094 77.557 3.1% 76.937 79.131 2.7% 15 61.148 69.336 11.8% 62.649 70.756 11% 20 62.292 70.03 11% 63.821 71.464 10% 25 70.506 74.904 5.8% 72.237 76.432 5.4% 30 82.593 81.809 0.94% 84.62 83.451 1.3% table 5, continue fundamental natural frequency (hz) boundary conditions cfcc time (min) experimental ansys error 5 69.497 74.885 7.1% 10 76.844 79.131 2.7% 15 62.573 70.756 11% 20 63.743 71.464 10% 25 72.149 76.432 5.4% 30 84.517 83.451 1.3% table 5 gives the experimental and numerical comparison of fundamental natural frequency after temperatures effect using different boundary conditions. at time of (t = 15min) both experimental and numerical procedures give the lowest value of frequency because this affords a lower value of amplitude. in ansys program the cccf and cfcc boundary conditions give the same value of frequency because the shear coupling effect boundary conditions is symmetric louay s. yousuf al-khwarizmi engineering journal, vol. 5, no. 3, pp 28 37 (2009) 33 about y-axis. all ansys values are different because ansys is an approximate solution. the error between experimental and numerical value of fundamental natural frequency is too high at time of (t = 15 min) because at this time the elastic moduli are small and the frequency is a function of elastic moduli. the denominator of percentage error law for fundamental natural frequency is quite little; but the difference between experimental and numerical values is high and this gives a large error value of percentage error. also in table 5, the frequency is not strange because these values vary with time harmonically and with sinusoid ally according to a fluctuating varied temperature. table 6 shows the comparison of maximum percent overshoot of composite plate before and after temperature effect varies with different boundary condition. the plate has minimum percent overshoot which reaches the steady state faster than the other plates because it has minimum values of both rise time and settling time. the increasing of clamped edges gives decreasing in maximum percent overshoot. table 6, maximum percent overshoot before and after temperatures effect. boundary conditions before temperatures effect after temperatures effect cfcf 70.715% 27.2922% cccf 51.476% 22.205% cfcc 70.722% 22.49% a structural dynamic problem differs from its static loading counter part in two aspects: first, the magnification factor (dynamic vibration resistance amplitude factor) is applied as a function of time or frequency or both of them. second, these time or frequency varying load applications induced time or frequency. as mentioned previously the magnification factor varies sinusoid ally with time for cfcf boundary condition as given in table 7 and the reduction in magnification factor makes the system more stable with small overshoot peak. time (t = 15 min) chosen for this operation is because this time gives reduction in vibration resistance amplitude factor while it decrease the fundamental natural frequency. table 7, magnification factor varies with time after temperatures effect. time (min) magnification factor 5 0.971 10 1.074 15 0.874 20 0.891 25 1.008 30 1.181 the relationship between amplitude and impact time before and after temperatures effect for (5, 10, 15, 20, 25 and 30) can be found to choose the best response time. fig. 4 shows a comparison of the amplitudes before and after temperatures effects vary with time for cfcf boundary condition. the two successive amplitudes to obtain the logarithmic decrement can be taken. time chosen for this comparison is 15 min because this time gives a large reduction in both amplitude and natural frequency values than the others. fig.4. amplitude vs. time before and after temperatures effect. the dangerous natural frequency at first mode has occurred and lead to resonance. fig. 5 illustrates the comparison of the amplitudes before and after temperatures effects vary with damped forced frequency for cfcf boundary condition. the time chosen for this comparison is 15 min because this time gives a large reduction in both amplitude and damped forced frequency louay s. yousuf al-khwarizmi engineering journal, vol. 5, no. 3, pp 28 37 (2009) 34 values than the others time. after temperature effect the peak’s amplitude is reduced with the same values above and below the vibration centerline until approaches the steady-state case of both time and damped forced frequency as shown in figs. 4,5. fig.5. amplitude vs. damped forced frequency before and after temperatures effect. fig. 6. fundamental natural frequency vs. time after combined temperatures effect. fig. 7. dynamic mechanical property vs. time after combined temperatures effect. figs. 6, 7 illustrate how the fundamental natural frequency and dynamic elastic moduli vary sinusoidal with conditioning holding time after combined temperatures (60 and -15 ) affect using different boundary conditions. at time (t = 15 min) a large reduction in frequency and elastic moduli values occurred due to the reduction bending stiffness of the laminate. fig. 8 gives the logarithmic decrement after combined temperatures effect varies with time using different boundary conditions. cccf is the best boundary condition at time (t = 15 min) because it affords a large value of logarithmic decrement and gives a reduction in both natural frequency and amplitude values with high damping factor. fig.8. logarithmic decrement vs. time after combined temperatures effect. 5. conclusion  at holding time (t = 15 min) the increasing of free edges of laminate plate leads to decreasing the value of fundamental natural frequency because of the absence of the shear coupling effect from clamped edges.  the best prediction holding time is at (t = 15 min) because this time gives a minimum of natural frequency, dynamic elastic moduli and magnification factor values to avoid a large response of composite laminate plate.  the damping factor increases when using combined temperatures effect such (0.382, 0.432, and 0.429) at (cfcf, cccf, and cfcc) respectively because the polymer matrix composites have temperaturedependent mechanical properties. louay s. yousuf al-khwarizmi engineering journal, vol. 5, no. 3, pp 28 37 (2009) 35  cccf is the better boundary condition in the field of maximum percent overshoot than cfcf and cfcc boundary conditions because this boundary condition affords minimum value of maximum percent overshoot. notation a large plate length b small plate breadth modulus of elasticity at modulus of elasticity along xdirection modulus of elasticity along ydirection modulus of elasticity of composite plate along x-direction modulus of elasticity of composite plate along y-direction modulus of elasticity of composite plate along z-direction modulus of rigidity in 1-2 plane modulus of rigidity in 2-3 plane modulus of rigidity in 1-3 plane h plate thickness mass density for fiber mass density for composite p.o. maximum percent overshoot maximum alternative amplitudes (i = 1, 2) greek letters fiber volume fraction fiber density fiber matrix fiber weight fraction logarithmic decrement damping ratio natural frequency damped forced frequency poisson's ratio in 1-2 plane poisson's ratio in 2-3 plane poisson's ratio in 1-3 plane 6. references [1] d.a. saravanos, and c.c. chamis, "computational simulation of damping in composite structures", nasa technical memorandum, lewis research center, 29 june 1 july, 1989. [2] hacene bouadi. c. t. sun, "hygrothermal effects on structural stiffness and structural damping of laminated composites", journal of materials science, vol. 25, no. 1, p.p. 499-505, 1990. [3] p.k. parhi, s.k. bhattacharyya, and p.k. sinha, "hygrothermal effects on the dynamic behavior of multiple delaminated composite plates and shells", journal of sound and vibration, science direct, vol. 248, issue 2, p.p. 195-214, 22 november, 2001. [4] xinyun guo, adam przekop, and chuh mei, "reduction of random response of composite plates using shape memory alloy in thermal environments", journal of structural dynamics & materials conference, 19-22 april, 2004. [5] praveen kumar kavipurapu, "forced vibration and hygrothermal analysis of composite laminated beams under the action of moving loads", university of west virginia, department of mechanical and aerospace engineering, m.sc. thesis, 2005. [6] mehmet c¸olako˘glu, "damping and vibration analysis of polyethylene fiber composite under varied temperature", turkish j. eng. env. sci., vol. 30, p.p. 351357, 2006. [7] shi-rong li, r. c. batra, and lian-sheng ma, "vibration of thermally post-buckled orthotropic circular plates", journal of thermal stresses, vol. 30, p.p. 43-57, 2007. [8] ramadan j. mustafa, "temperature dependence of dynamic modulus and damping in continuous fiberreinforced al(alloy) matrix composites at elevated temperatures", jordan journal of mechanical and industrial engineering, vol. 2, no. 1, p.p. 15-21, march, 2008. [9] kleinholz r., and molinier g.," aramid carbon and glass fiber specialized reinforcement materials for composites", vetrotex fiber world, no. 22, p.p. 13, 1986. [10] b.c. ray, “ thermal shock and thermal fatigue on delamination of glass fiber reinforced polymeric composites”, journal of reinforced plastics and composites, vol.24,no. 1, 2005. louay s. yousuf al-khwarizmi engineering journal, vol. 5, no. 3, pp 28 37 (2009) 36 [11] william.t. thomson, “theory of vibration with applications”, second edition, englewood cliffs, new jersey, 1981. [12] robert m. jones," mechanics of composite materials", mcgraw-hill book company, 1975. 37 28 صفحة ،3 العدد ،5 المجلد الهندسية الخوارزمي مجلة يوسف صباح لؤي (2009) 37 حنبؤ الوقج للخصرف الذيناميكي اللياف الزجاج المقواة مع مادة البوليسخر المركبت الخاضعت لخقلباث درجاث الحرارة المخخلفت لؤي صباح يوسف جبيؼت بغذاد / كهٍت انهُذست/ قسى انهُذست انًٍكبٍَكٍت الخالصت قذ ححققج ػُذ حُبؤ انشيٍ ححج درجبث (انٍبف سجبجٍت يحبكت يىضىػت فً يبدة انززيىسٍج بىنٍسخز االسبص)حقهٍم خىاص االهخشاس نهًبدة انًزكبت حز، -يزبج-يزبج-حز، يزبج-يزبج-حز-يزبج) ببسخخذاو رالد اَىاع يٍ شزوط انذػى يزم ( درجت يئىٌت15درجت يئىٌت انى 60)حزارة يشخزكت ويخغٍزة انذٌُبيٍكٍٍٍ، 2-1خىاص االهخشاس هً انخزدد انطبٍؼً، كال يٍ يؼبيم انًزوَت ببالحجبهٍٍٍ انطىنٍٍٍ ويؼبيم انقض ببنًقطغ . (يزبج-يزبج-حز-يزبج االنٍبف انشجبجٍت انًحبكت هُذسج خظٍظب نخقىٌت انبىنًٍز ونكٍ . انخزدد انطبٍؼً نهُظبو هى دانت نخىاص انًزوَت، االبؼبد، وانكخهت. ويؼبيم انخخًٍذ اٌ . انززيىسٍج بىنٍسخز انغٍز يشبغ انشبئغ االسخؼًبل ٌؼزع حىاسَب جٍذا نخىاص االهخشاس ػُذ درجبث انحزارة انًؼخذنت او انبٍئٍت، واٌضب رخٍض انزًٍ اٌ اخخببر . انخفبوث يببٍٍ انًبدة االسبص واالنٍبف انًحبكت حؼطً انذور انسبئذ نًٍكبٍَكب االنٍبف حٍذ اٌ انًبدة االسبص هً حطىر يسبحبث انٍبث انضزر يٍ االَحذار انحزاري ( درجت يئىٌت75)دقٍقت يٍ حظت انىقج حٍذ اٌ انًبدة انًزكبت يؼزضت انى (30، 25، 20، 15، 10، 5)االهخشاس انحز َفذ نـ . (ansys. 9)انُخبئج طُفج انى َخبئج ػًهٍت وَخبئج بىاسطت انؼُبطز انًحذدة ببسخخذاو بزَبيج . نؼشز يزاث نًخخهف اوقبث يزاحم انخشغٍم this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 19, no. 4, december, (2023) p. p. 5666 secure seaport management system using blockchain technology ali h. hamad department of information and communication / al-khwarizmi college of engineering/ university of baghdad/ baghdad/ iraq email: ahamad@kecbu.uobaghdad.edu.iq (received 21 january 2023; accepted 30 august 2023) https://doi.org/10.22153/kej.2023.08.001 abstract worldwide, shipping documents are still primarily created and handled in the traditional paper manner. processes taking place in shipping ports as a result are time-consuming and heavily dependent on paper. shipping documents are particularly susceptible to paperwork fraud because they involve numerous parties with competing interests. with the aid of smart contracts, a distributed, shared, and append-only ledger provided by blockchain technology allows for the addition of new records. in order to increase maritime transport and port efficiency and promote economic development, this paper examines current maritime sector developments in iraq and offers a paradigm to secure the management system based on a hyper-ledger fabric blockchain platform. the performance evaluation of the proposed system implies two scenarios: one organization and two organizations by examining throughput and latency. high transaction transmission rates on large block sizes produced positive results. similarly, employing a small block size and higher send rates results in poor performance. additionally, it was noted that throughput will decrease and latency will rise as the number of organizations increases. block size and block timeouts should be high in applications with many concurrent transactions in order to maintain good throughput. keywords: hyper ledger fabric, caliper fabric, maritime, seaport management, port community system. 1. introduction the backbone of a nation's foreign trade and its entryways into the globe are its ports. along with playing a crucial role in accelerating the process of economic development, they are seen as the key link in the multimodal transport system. however, the maritime sector needs greater advancements in communication technology and the digitalization of seaport management systems in the age of globalization and the expanding demand for novel technologies. [1] port community system (pcs) refers to early initiatives to redesign the port and shipping management processes in a digital environment. port authority, customs, terminal operator, consolidation center, and freight forwarder are just a few of the key players who have full or partial bases within the port site. pcs serves as its information hub. the primary goal of pcs is to mailto:ahamad@kecbu.uobaghdad.edu.iq mailto:ahamad@kecbu.uobaghdad.edu.iq https://doi.org/10.22153/kej.2023.08.00 ali h. hamad al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 5666 (2023) 57 make it possible for intelligent online information and document exchange compared to traditional procedures, which include using tangible methods like phone calls, faxes, and physical signatures. pcs converts the workflow to digital format in order to shorten the time that papers must wait for approvals using communication tracking and realtime data updates. importantly, pcs employs a centralized strategy to maintain and reroute the document flow, which means there is only one main authority in charge of controlling data storage and confidentiality [2]. what type of data is shared throughout the globalized maritime supply chain? the majority of this data consists of port and shipping management systems. these details, such as whether a container has been gated, staffed, or what time it is expected to arrive (eta) at its destination, are in fact port management and shipping key points. however, documents in maritime, both structured and unstructured such as pdfs, scans, photos, etc. go beyond that by making them ready for the parties involved in the supply chain. to develop workflow utilizing smart contracts, such as "smart" bills of lading, clearance, insurance, etc., they must be approved, updated, and accessible [3]. just like any other “e-systems”, pcs suffer from security and privacy issues that must be addressed since any penetration could cause many problems in different fields. blockchain technology has been researched in container transportation to prevent wasting time handling containers and minimize the cost of logistics tasks, boosting a country's ability to compete internationally. in order to reduce the danger of document falsification and increase data and contract security, blockchain has been utilized to secure customs receipts and documents with trust procedures [4]. six nations surround iraq on all sides. to the south are saudi arabia and kuwait, to the west are jordan and syria, to the north is turkey, and to the east is iran. iraq has a limited coastline of only 48 kilometres, which is located between kuwait and iran's borders. all of its ports are located in basra province. there are two oil terminals in iraq, as well as almaqil, khoralzubayr, abu-flous, and umm-qasr port, which is the country's principal port for international trade. as a transit point for oil being exported out to the persian gulf and for imports, the ports constitute a vital link in the economy of iraq. figure 1 shows the map of all iraqi seaports [5]. in this paper, a performance evaluation of a proposed secure pcs system-based hyper-ledger fabric blockchain technology has been introduced, with a comparison of performance using one and two organizations. two main metrics have been taken for system evaluation which are throughput and latency. the paper is organized as follows: section 2 shows related work, while section 3 describes an overview of intelligent transport systems used in seaports. in section 4, the hyperledger fabric platform is described while section 5 shows the results of the performance evaluation. finally, a conclusion about the proposed system is introduced in section 6. ali h. hamad al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 5666 (2023) 58 fig. 1. iraqi seaport in basra province [5]. 2. related work the use of blockchain technology and electronic voting has been covered in a number of publications. these papers outline various strategies and objectives that are reached through various methods. [2] demonstrated how a blockchain-based scenario for handling shipping documents has been developed as a precise answer to the problems that pcs was designed to address, including data security, accelerated communication, the removal of the role of the central gatekeeper, and the establishment of p2p communication for both transaction visibility and permission transparency.[6 ] introduced the use of smart contracts inspired by shipping port procedures that are implemented into the ganache private blockchain, bringing the blockchain's immutable nature, trust, decentralization, and privacy into the entire shipping process.[7] showed what impact industry 4.0 might have on seaports' use of more complex business models and how this impact is produced, paying special attention to the potential roles of technology push and market pull mechanisms. then, this model is assessed using a preliminary study on barcelona port. [4] provided a blockchain-based permission hyper-ledger network electronic voting system for the elections for the iraqi council of representatives. blockchain technology consists of an immutable distributed ledger that is updated by each network participant. [5] build a website that will register inland ships and sailors and then let users access their information. the scheme proposes to use blockchain to give ships and sailors e-licenses. the suggested solution will assist in developing a portal for data collection and remote data viewing. the ministry of ports, shipping, and waterways will also post information about inland vessels and their owners in the database. [9] presented an intelligent decision support system (i-dmss) that is particularly based on blockchain technology and directs into the information sharing construction defined for a particular strategical business process where the seaport is concerned with the capacity to share data with a partner seaport that is a part of the same inter-organisational system.[10] offered blockshipping, a decentralized platform for smart booking and release of containers, as one of the blockchain-based maritime supply chain system (bmscs )applications. its actual advantages, weaknesses, and major players are explored along with the conceptual foundation of bmscs. [8] presented a blockchain with crowdsourcing for a port management system where the cognitive domains (cstc), social, and cyber technological aspects of crowdsourcing technology, smart ports, and knowledge creation process are interrelated. table 1. shows a comparison of the previous work compared with the present work. ali h. hamad al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 5666 (2023) 59 table 1, comparison of previous work. 3. seaport it overview with significant effects on all business sectors, digital transformation is of the utmost importance. here, we use ports and maritime shipping logistics as examples of those advances. in other words, seaports are particularly impacted by technological change since they are participants in global supply networks. in figure 2, a diagram of port supply chain operations is shown. digital innovation is crucial for ports to remain competitive because the logistics industry has such high standards for things like costs, efficiency, security, and sustainability. historical trends demonstrate how digital innovation might influence port modernization. reviewing the results of previous advances and their effects on port operations is necessary to comprehend the issues that will be faced in this area in the future. fig. 2. maritime supply chain [12]. ref platform application performance evaluation [2] none shipping documents none [4] hyper ledger fabric e-voting throughput and latency [5] none e-license to ships and seafarers none [6] ganache shipping documents none [7] none seaport management none [8] crowdsourcing port management none [9] i-dmss seaport capacity none [10] blockshipping smart booking for containers none present work hyper ledger fabric maritime and seaport management scalability, throughput,and latency ali h. hamad al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 5666 (2023) 60 associated information flows have a significant impact on the effectiveness and security of connected freight transfers. the use of information and communication technology (ict) has advanced to become a crucial factor for the competitiveness and success of ports, decisionmaking, facilitating communication and enhancing the efficiency, visibility, productivity, and safety in port procedures that are impacted by various conditions [11]. the options are nearly unlimited, and as a result, the development of iot and the utilization of big data raise the possibility that logistics will develop into a data-centric economy where information is valued more highly than the capacity to move cargo. there are new business models, alliances, and issues about who is best suited to lead these partnerships as a result of the increased interest in and advancements in the field of iot and big data analytics. big data analytics and iot have an impact on many processes, thus many stakeholders must collaborate to make it work [12]. the conceptual model above illustrates a case study of the logistics process for a shipping contract, which includes the following steps: commercial agreement, space reservation, export processes, container storage, inspection of forest and agricultural products, coordination of land cargo, and reception in the destination port. among other things, the cargo area, ship evacuation procedures, and bills of lading. a portion of the document management system is displayed. this system is made up of the administrative entity, the terminals, the private businesses that offer logistics services to international trade, and the governmental organizations that have supervision responsibilities. 4. blockchain technology a distributed database called blockchain (bc) enables a dispersed peer-to-peer network, guaranteeing participants safe and trustworthy link and communication. it is a novel technology that duplicates and disperses transactions across the network of computers involved in the blockchain by using distributed ledgers. a collection of public keyprotected blocks with time-stamped transactions that have been validated by the network community. the owner's digital signature authorizes transactions in these blocks, authenticating and safeguarding them. as a result, the ledger's data is very secure [13][14]. blockchain architecture and blockchain working methodology are the two components of blockchain technology. all of the data pertaining to legal transactions is contained in a block, which is the core data component of a blockchain system and is generated by cryptography. a basic "block" structure consists of two parts: the block header and the block content. the structure of the blockchain is depicted in fig. 3 [37]: a. block header: the block header contains the block number, previous hash block, current hash block, time stamp, block size, and nonce value. b. block data (block body): this part of the block provides all the information about the block, including the number of transactions overall and the percentage of validated transactions in each block. c. merkle tree: the merkle tree is used to hash and organize the block's transactions. by pairing and hashing two transactions, then repeating for the top level, one can extract the merkle root. following certification, the block is made available to all network users. a genesis block is a blockchain's very first entry. ali h. hamad al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 5666 (2023) 61 fig. 3. the structure of blockchain [15]. 5. hyper ledger fabric blockchain a decentralized, distributed, and unchangeable database called the blockchain keeps track of transactions in time-stamped blocks joined by hashes. participants in the p2p blockchain network are identifiable by their private and public keys. the cryptographic hash function of the previous block, the data transactions, which are frequently organized as a merkle tree data structure, and the timestamp are the three main parts of a blockchain block. a block's transaction data cannot be changed after it has been recorded without also changing the blocks that came before it [16,17]. the target market for hyper-ledger fabric's permission blockchain technology is businesses [18]. to make deployment easier, hyper-ledger fabric was included in a microservices-based architecture. the ledger was built using a nosql database called couchdb. the generation of smart contracts using general-purpose languages is supported by the hyper ledger fabric. all of the codes that can be called by transactions are listed in a chain code, which is a smart contract in the ledger fabric. endorsement policies are included with chain codes and are applicable to the associated smart contracts. the confidentiality of transactions between network participants can be ensured via a channel isolation method. each channel keeps a separate ledger, ensuring that only member nodes in the channel may access the transaction and data. the elements that make up hyper-ledger peers, couchdb, orderers, certification authority (ca), and chain code are the microservices that construct a hyper-ledger blockchain network. each microservice's deployment method made use of docker containers. remote procedure calls are used to connect them [19, 20]. there are several aspects of the hyper-ledger fabric, including rich ledger queries, no transaction costs, and types of consensus (solo, raft, and kafka). document workflow management brings comparable values but differs in terms of the suggested solution to the same problems as the previously announced port community system. the fundamental idea behind document workflow management is to incorporate blockchain into an already existing database, erp, and accounting system, standardize documents, and bring the entire data flow online while swapping out paper approvals for digital ones. approvals act as time stamps that can be used to trace faults or settle conflicts between parties, such as when items inside a container arrive damaged. the whole system's interconnectedness amongst the involved parties also serves to ensure security. figure 4. shows the workflow diagram of the hyper ledger fabric platform. ali h. hamad al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 5666 (2023) 62 fig. 4. hyperledger fabric workflow [11]. 6. performance evaluation of proposed system this section provides an analysis of the proposed permission hyper ledger fabric blockchain's throughput (measured in transactions per second, or "tps"), average latency (measured in seconds, or "sec"), and scalability (i.e., the number of participants that the blockchain network can serve). it is necessary to explain the effect on changeable fabric network components. additionally, different transaction speeds and block sizes were used to execute the scenarios. the performance of the hyper-ledger fabric can be impacted by a number of fabric network components, each with a different level of configuration. these parts might be categorized as hardware or software. in the case of software, these factors include block size, block timeout, ordering service, smart contract programming language, ledger database, client count, tls usage, number of peer endorsers, number of organizations, and endorsement policy. it displays cpu utilization, the hard drive's kind and speed, the amount of memory, the cpu speed, and the network speed for hardware. the calliper may generate a performance report that can be used to gauge and assess the degree to which various hyper-ledger blockchain platforms are successful, as well as the latency (minimum, maximum, average, percentile), throughput, and resource usage (cpu, memory, network io, etc.). 6.1 case 1: one organization in this case, several block sizes and transaction send rates have been evaluated in terms of performance. figure (5. a) depicts the transaction throughput, which rises with increasing block size to 100 transactions in each block. the greatest throughput attained was approximately 108 transactions per second (tps). it should be noticed that as the block size increased by 150 and 200 transactions, the throughput gradually started to decline. figure (5. b) demonstrates that when the block size grows to 100 transactions, the average latency reduces. the average latency increases slightly when the block size is increased to 150 and 200 transactions, suggesting that this particular test setting does not significantly influence performance when the block size is increased to more than 100 transactions per block. furthermore, with low transmit rates, such as 50 transactions per second, better latency and throughput have been observed when utilizing lower block sizes, such as 10 transactions; hence, increasing block sizes did not significantly affect performance, but it was still apparent. ali h. hamad al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 5666 (2023) 63 6.2 case 2: two organizations in light of this hypothetical situation, research on the effective evaluation of different block sizes and transaction send rates has been put to the test. figure (5. c) demonstrates that as block size was increased to 100 transactions, the transaction throughput rose, with (61 tps) being the greatest throughput attained. while the throughput somewhat dropped when the size of the block was increased to 150 and 200 transactions. figure (5.d) demonstrates that the latency decreases as the block size increases up to 100 transactions, with a little greater growth in delay when the block size climbed to 150 and 200. according to the findings, performance is not greatly affected by increasing the block size to more than 100 transactions. using a smaller block size, such as 50 transactions, resulted in better throughput and latency for a low send rate, like 50 tps, so performance was not significantly impacted by raising the block size, but it is still apparent. in this work, a block size up to 200 with tps up to 250 has been introduced with one and two organizations to investigate the effect of scalability on the proposed system design. as compared with previous work, a good result was obtained in terms of throughput and latency when using additional organizations. ali h. hamad al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 5666 (2023) 64 fig. 5. performance evaluation of proposed system. 7. conclusion this work aimed to provide fresh perspectives on the interactions between seaport management systems and the development of blockchain technology in relation to seaports. by adjusting the transaction transmit rate, block size, and block timeout, this study also examines the throughput and latency performance of the hyper-ledger fabric blockchain. to obtain high performance in systems that have large concurrent transactions, the block size and block timeout should be substantial. in conclusion, the suggested hyper-ledger fabric blockchain network, which is built on a secure management system, is appropriate and might satisfy security needs such as eligibility, traceability, 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[17] y. li et al., “a blockchain-based selftallying voting protocol in decentralized iot,” ieee trans. dependable secur. comput., vol. 19, no. 1, pp. 119–130, 2022, doi: 10.1109/tdsc.2020.2979856. [18] k. m. khan, j. arshad, and m. m. khan, “investigating performance constraints for blockchain based secure e-voting system,” futur. gener. comput. syst., vol. 105, pp. 13– 26, apr. 2020, doi: 10.1016/j.future.2019.11.005. [19] a. m. al-madani, a. t. gaikwad, v. mahale, and z. a. t. ahmed, “decentralized e-voting system based on smart contract by using blockchain technology,” 2020, accessed: sep. 16, 2021. [online]. available: https://ieeexplore.ieee.org/document/929958 1/. [20] s. chaisawat and c. vorakulpipat, “faulttolerant architecture design for blockchainbased electronics voting system,” in 2020 17th international joint conference on computer science and software engineering (jcsse), 2020, pp. 116–121, doi: 10.1109/jcsse49651.2020.9268264. https://doi.org/10.1016/j.rtbm.2022.100803 https://doi.org/10.18280/isi.270506 (2023) 56-66، صفحة 4، العدد19مجلة الخوارزمي الهندسية المجلد علي حسين حمد 66 الكتلنظام ادارة الموانئ االمن باستخدام تقنية سالسل علي حسين حمد قسم هندسة المعلومات واالتصاالت/ كلية الهندسة الخوارزمي/ جامعة بغداد ahamad@kecbu.uobaghdad.edu.iqj :البريد االلكتروني الخالصة غرق العمليات التي في جميع أنحاء العالم ، ال يزال يتم إنشاء مستندات الشحن بشكل أساسي والتعامل معها بالطريقة الورقية التقليدية. ونتيجة لذلك ، تست قية ألنها تتضمن العديد من تتم في موانئ الشحن وقتًا طويالً وتعتمد بشكل كبير على الورق. مستندات الشحن معرضة بشكل خاص لالحتيال في األعمال الور بإضافة سجالت blockchainاألطراف ذات المصالح المتنافسة. بمساعدة العقود الذكية ، يسمح دفتر األستاذ الموزع والمشترك والملحق فقط الذي توفره تقنية رقة التطورات الحالية للقطاع البحري في العراق وتقدم نموذًجا جديدة. من أجل زيادة كفاءة النقل البحري والموانئ وتعزيز التنمية االقتصادية ، تدرس هذه الو . يتضمن تقييم أداء النظام المقترح سيناريوهين ؛ منظمة واحدة ومنظمتان من hyperledgerالنسيجية blockchainلتأمين نظام اإلدارة القائم على منصة عالية على أحجام الكتل الكبيرة عن نتائج إيجابية. وبالمثل ، يؤدي استخدام حجم كتلة صغير خالل فحص اإلنتاجية و التاخير. أسفرت معدالت نقل المعامالت ال ب أن يكون ومعدالت إرسال أعلى إلى أداء ضعيف. باإلضافة إلى ذلك ، لوحظ أن اإلنتاجية ستنخفض وسيزداد وقت االستجابة مع زيادة عدد المنظمات. يج بيقات التي تحتوي على العديد من المعامالت المتزامنة من أجل الحفاظ على معدل نقل جيد.حجم الكتلة ومهلة الحظر عالية في التط mailto:ahamad@kecbu.uobaghdad.edu.iqj 1. introduction 2. related work this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 20, no. 3, september, (2024), pp. 8796 determination of the optimum conditions for urease extraction from chickpea seeds using (design expert software) sarah s. kurdi* and mohanad j. m-ridha** **,* department of environmental college of engineering/ university of baghdad/ baghdad/ iraq *email: sarhslman1999@gmail.com (corresponding author) **email: muhannadenviro@yahoo.com (received 18 june 2023; revised 10 september 2023; accepted 19 september 2023; published 1 september 2024) https://doi.org/10.22153/kej.2024.09.003 abstract this study aimed to utilise response surface methodology (rsm) to determine the optimal conditions for extracting urease from a plant source and evaluate its biochemical properties. chickpea seeds were selected as the source of urease. results showed that chickpea seeds had a high enzyme activity (3.99 u/mg protein) under the best extraction conditions of ph 7.99, tris base buffer concentration of 0.2, time of 60 minutes and ratio of 1:13 (g: ml). when a second-order polynomial model was used, the predicted correlation coefficient (pred. r2) was 0.8477, the adjusted correlation coefficient (adj. r2) was 0.9333 and the correlation values (r2) were 0.9665, indicating that the predicted models and experimental values agreed very well. the method has the potential to enhance the cost-effectiveness of enzyme production through large-scale manufacturing and offers an economical alternative to other techniques. keyword: chickpeas; plants; enzyme; extraction; rsm _ 1. introduction ureases (ec 3.5.1.5) are metalloenzymes that depend on nickel and break down urea into co2 and ammonia [1]. these enzymes are present in various organisms, including plants, algae, yeasts and filamentous fungi. ureases from plants and fungi are made up of identical protein units, while bacterial ureases are made up of complicated repetitions of two or three subunits of varying sizes [2]. ureases are applied in numerous fields, such as biosensors for measuring urea in human blood, diagnostic kits for urea measurement and ureareducing agents in alcoholic beverages [3]. plant and microbial ureases have other biological functions, such as activating blood platelets, killing insects and killing fungi, which suggest that they are involved in the defence mechanisms of plant cells [4]. the crystallisation of urease enzymes extracted from jack beans marked a pioneering achievement in laboratory studies, and these enzymes remain the most extensively studied plant ureases. other studies isolated seed urease from watermelon and cajanus cajan [2]. a number of variables, including environmental conditions (such as temperature and ph), type of enzyme used and substrate, influence the rate of urea hydrolysis. temperature and ph have been investigated for their effect on urease activity [5]. research of urease activity at various temperatures discovered that it was most effective between 35 °c and 50 °c; at 60 °c, the enzyme retained more than 80% of its activity [6]. jack bean urease was found to be most active at 65 °c. biotechnology has gained increasing interest because of the growing need for efficient urea removal technologies in various contexts [7]. urea is used in treatment of industrial wastes, manufacture of alcoholic beverages, haemolysis and life support systems in space missions. bacterial ureases have complicated repeats of two or three subunits of varying sizes, while plant and fungal ureases are homomailto:sarhslman1999@gmail.com mailto:muhannadenviro@yahoo.com https://doi.org/10.22153/kej.2024.09.003 sarah s. kurdi al-khwarizmi engineering journal, vol. 20, no.3, p.p. 8796(2024) 88 oligomeric and contain identical protein repeats [8]. the efficiency of enzyme function is frequently highly dependent on its basic structure and local environment. anything in the surrounding environment that alters the enzyme's conformation or blocks its active site can affect its function [7]. through a series of tests conducted using the design expert tool, the present study aims to identify the ideal conditions for urease enzyme extraction from chickpea seeds. we will use central composite design (ccd) to establish experimental circumstances and build a statistical model to forecast extraction conditions. the effect of process variables on responses will be assessed using anova. we will then conduct experiments to confirm the optimal extraction conditions predicted. the methodology will establish a connection between a desired response or outcome and a set of process variables by applying statistical methods. response surface methodology (rsm) requires simple and effective experimental designs [9] and may fix problems with linear and nonlinear multivariate regression while decreasing the number of experimental trials. 2. materials and methods chickpeas were hand-picked from an iraqi market. experiments were carried out using highgrade chemical reagents acquired from trustworthy vendors. the following chemicals were purchased from hi-media co.: sodium nitroprusside, tris base, tris hcl (c4h11no3), and urea (ch4n2o). coomassie brilliant blue g-250, sodium acetate (ch3coona) and sodium hydroxide (naoh) were procured from bdh. sodium dibasic and sodium dihydrogen phosphate (nah2po4.12h2o) were provided by cdh, and ammonium chloride (nh4cl) was supplied by sigma. sodium hypochlorite (naclo) was bought from sehat company, and phenol was obtained from thomas baker co. these chemical reagents were meticulously chosen to guarantee the precision and dependability of the experimental processes and were commercially available and of highest possible purity. 2.1 sample preparation a locally accessible cultivar of spherical, lightcoloured chickpeas called kabuli was sourced from türkiye and used in the experiment to evaluate urease activity. pozzolana buffer solution, which had a concentration of 0.02 m and a ph of 7.0, was used to crush and extract chickpea seeds. a 10 ml of the buffer solution was used to collect 1 gram of plant seeds after leaving the sample at room temperature for 15 minutes. 2.2 urease assay urease activity was measured using a modified berthelot reaction [10]. the amount of ammonia released was measured using the nh4cl standard curve. glassware were sterilised by washing in a solution of warm, diluted hydrochloric acid and rinsed well with distilled or deionised water. about 1 ml of the seed extract was mixed with 1 ml of 500 mm urea solution containing phosphate buffer (100 mm, ph 6.8) and 0.8 ml of the same buffer. the mixture was placed in a water bath and incubated at 37 °c for 1 h. the reaction was terminated by applying heat at 80 °c for 5 minutes. a test sample, referred to as the ‘black sample’, was prepared. the plant seed extract was heated before adding to the reaction mixture. the reaction mixture (1 ml) was mixed with 10 ml of berthelot reagent to determine ammonia concentration. the berthelot reagent consisted of 5 ml of 0.01 m reagent a (containing 5 g of phenol and 0.02 g of sodium nitroprusside) and 5 ml of 0.01 m reagent b (containing 2.5 g of sodium hydroxide and 8.4 ml of sodium hypochlorite). the mixture was then diluted in 500 ml of distilled water and incubated in a water bath at 37 °c for 1 hour. urease activity was assessed by quantifying the increase in absorbance at a wavelength of 625 nm. an enzymatic activity unit is the amount of enzyme liberated from ammonia within 1 minute under the optimum conditions. the concentration of protein was determined using bradford’s technique [11]. urease activity =ab/slope/(t×c) where: 𝐴𝑏 𝑠𝑙𝑜𝑝𝑒 : is the concentration of ammonia, t: is the time of reaction (60 min) c: is a constant [12] 2.3 urease extraction in a mortar, 1 g of plant was mixed with 10 ml of phosphate buffer at ph 7.0 for 15 minutes at room temperature to achieve a homogenous mixture. the mixture was centrifugation at 10,000 rpm for 15 minutes and filtered through whatman no. 1 filter paper (0.1 mm thick, chinese manufacturer) to remove all cellular debris from the slurry. protein content, enzyme activity and specific activity of the supernatant were measured. sarah s. kurdi al-khwarizmi engineering journal, vol. 20, no.3, p.p. 8796(2024) 89 2.3.1 extraction buffer the sample with the maximum activity, as indicated during preliminary screening, was selected to investigate the effect of the buffer used for extraction. the selected plant sample was homogenised for 15 minutes at 30 °c by using various buffers: at ph 4, 5 and 6, 0.2 m sodium acetate; at ph 7, 0.2 m phosphate-buffered saline; and at ph 8 and 9, 0.2 m tris-base. we examined protein content, enzyme activity and any significant interactions in triplicate. 2.3.2 concentration of extraction buffer extraction was carried out using different concentrations (0.085 m to 0.2 m) of tris base buffer, sodium phosphate buffer, and sodium acetate buffer to determine the appropriate concentration for extraction. 2.3.3 extraction ratio extraction ratio was optimised using different buffer ratios, ranging from 1:5 to 1:30 (w/v). in brief, 1 g of chickpeas were mixed with the appropriate extraction ratio followed by centrifugation at 10,000 rpm for 10 minutes and filtration using whatman no. 1 filter paper. the resulting clear supernatant represented the crude extract, which was then assayed for urease inhibitor activity. 2.3.4 extraction time optimal extraction time was determined by varying it from 5 to 120 minutes. 2.4 experimental design the experimental data obtained from ccd were analysed and fitted to a second-order polynomial model, as represented by the equation: y = β0 + ∑ βixi + ∑ βiixi2 + ∑ ∑ βijxixj … (1) where y represents the expected response, β0 is the intercept parameter, βi and βii are linear and quadratic coefficients and βij represents the interaction coefficients. xi and xj denote the coded values of the independent factors [13]. the ranges for each parameter were carefully selected to assess their effects on the efficiency of urease extraction. design expert software, which incorporated rsm and ccd, was utilised to simulate the experiments and determine the optimal conditions. a total of 25 individual experiments were simulated, and a second-order polynomial relationship was derived using rsm for subjective evaluation of urease output. the operating ranges for each parameter can be found in table 1. table 1, applied values and variables for urease extraction 2. 5 design expert modelling –rsm-ccd rsm provided excellent statistical tools for experimental design and data interpretation to optimise the process. rsm reveals the optimal condition under which a high yield of product that meets specifications is produced at the lowest cost. the present design of the experiment excludes the ccd model, which was previously incorporated into the theoretical framework [14]. the model was generated using a linear regression approach, with the inputs as coadded values [15]. we employed anova to determine how autonomous factors in regression affect the dependent variable. anova is a statistical method used to differentiate systematic factors from other factors and random factors to explain the observed aggregate variability within a data set. systematic factors, as opposed to random factors, affect the offered data set statistically [16]. factors units low (−1) high (+1) ph ----4 9 concentration mg/l 0.085 0.2 extraction ratio extraction time mg ml−1 min 1:5 5 1:30 120 sarah s. kurdi al-khwarizmi engineering journal, vol. 20, no.3, p.p. 8796(2024) 90 3. results and discussion 3.1 optimisation results after experimenting with several variables, such as extraction time, ratio, buffer and concentration, the optimum conditions for urease extraction from chickpeas were determined. the specific activity was 3.99 u/mg, and the best conditions for extraction were a water-to-solid ratio of 1:13 for 1 hour in 0.2 m tris-base buffer. urease extraction from various sources has been the subject of prior research into various buffers and ph values. according to hussein et al. [17], the optimal buffer for urease extraction from chickpeas was sodium acetate buffer (0.2 m, ph 5.0), which led to an enzyme with a specific activity of 1460 u/mg. enzyme extractability can vary depending on source combination and other interfering factors and is crucial to establish the optimal extraction period. contaminants should be removed before extraction to obtain a stable protein extract [18]. 3.2 anova table 3 shows the outcomes of the four variables tested by anova. the chosen regression models fitted the data well, with an r2 value of 0.9665. a strong agreement was found between the adjusted r2 (r2ad) value of 0.9419 and the anticipated r2 value of 0.8477, with a skewness of less than 0.2. a and an extremely high signal-to-noise ratio, as shown by an appropriate precision (ap) value of 17.204; hence, the models employed were statistically significant and accurate in describing the experimental data [19]. table 3 shows no significance in the misfit f values (0.5431, 0.7765), thereby adding credence to the significance and correctness of the quadratic model. with a cv% of 13.34%, the model was quite accurate and dependable for predicting experimental outcomes [20]. the quadratic models were used to determine the optimal conditions for urease extraction when the ap ratio exceeds four and the modified coefficient of determination is more than the 80% threshold. the right factor levels should be selected to obtain values closer to the average theoretical system efficiency [20]. specific activity equation: the predicted model shown in equation (2). specific activity = -0.490676 + 0.903056x1 4.37723x2 + 0.044360x3 0.000018x4 + 0.795855x1x2 0.000345x1x4 0.070835x2x3 0.012132x2x4 + 0.000117x3x4 0.065062x1 2 + 27.28951x2 2 0.001405x3 2 …(2) where x1: ph of solution x2: concentration of solution (m) x3: ratio (weight: volume) x4: extraction time (min) this equation can predict responses (specific activity) to different levels of each factor by expressing the levels in terms of the actual factors. original units at which the factors were measured were used when specifying the amounts of each element. 3.3 design expert modelling –rsm-ccd table 2 shows the experimental conditions and the results obtained from 25 experiments according to rsm. table 2 design experiment program for maximum enzyme urease extraction a:ph b:c0 m c:ratio d:time min. specific activity 4 0.01 30 120 2.36 4 0.085 15 58 2.3 4 0.2 30 5 2.53 4 0.2 30 85 2.62 4 0.085 15 58 2.45 4 0.2 5 120 2.68 4.93 0.01 5 5 2.71 5.3 0.01 24 5 2.61 5.38 0.15 5 5 3.11 5.5 0.01 5 110 2.5 5.78 0.13 21 120 2.78 5.78 0.13 21 120 3.2 sarah s. kurdi al-khwarizmi engineering journal, vol. 20, no.3, p.p. 8796(2024) 91 table 3, anova results for response surface of quadratic model r2 = 0.9665, r2 adjusted = 0.9419, rpredicted =0.8477 ,ap =17.204, cv = 13.34% 3.4 interactive effects of two variables the interaction effects of buffer and concentration on urease activity are depicted in figure 3a. the findings of this study demonstrate that within the ph range of 7–9 and with concentrations ranging from 0.162–0.2 m, there was a notable increase in urease activity. specifically, the specific activity reached a value of 3.99 u/mg. the ph of the enzyme environment plays a significant role in enzyme activity. the ph of the environment affects stability, while each enzyme has an ideal ph range where it performs at its best. in addition to the ph of the reaction mixture that influenced substrate–enzyme interactions, the enzyme was denatured by extremely acidic or alkaline conditions [21]. selecting a buffer solution whose ph is similar to the cell’s in vivo ph is critical to maintain protein integrity [22]. urease has been extracted from many sources by using different buffers and ph levels. an earlier work [23] extracted urease from proteus mirabilis by using 20 mm phosphate buffer with a ph of 7.5. 5.88 0.13 21 9.6 3.25 6.88 0.09 6.3 63 2.58 6.95 0.086 30 60 2.8 6.95 0.086 30 60 3.13 7.05 0.2 15 58 4 7.05 0.2 15 58 3.89 7.05 0.2 15 58 3.95 9 0.14 5 110 3.5 9 0.01 5 28 2.4 9 0.01 23 110 2.66 9 0.2 30 120 3.21 9 0.01 23 28 2.66 9 0.15 24 5 3.42 source sum of squares df mean square f-value p-value model 5.62 12 0.4683 28.88 < 0.0001 significant a-ph 1.13 1 1.13 69.74 < 0.0001 b-c0 2.47 1 2.47 152.24 < 0.0001 c-ratio 0.0485 1 0.0485 2.99 0.1094 d-time 0.0879 1 0.0879 5.42 0.0382 ab 0.2819 1 0.2819 17.39 0.0013 ad 0.0181 1 0.0181 1.12 0.3112 bc 0.0533 1 0.0533 3.29 0.0949 bd 0.0363 1 0.0363 2.24 0.1604 cd 0.0541 1 0.0541 3.34 0.0927 a² 0.6789 1 0.6789 41.88 < 0.0001 b² 0.2768 1 0.2768 17.08 0.0014 c² 0.1959 1 0.1959 12.08 0.0046 residual 0.1945 12 0.0162 lack of fit 0.0840 7 0.0120 0.5431 0.7765 not significant pure error 0.1105 5 0.0221 cor total 5.81 24 sarah s. kurdi al-khwarizmi engineering journal, vol. 20, no.3, p.p. 8796(2024) 92 the combination of the extraction ratio (10–15, w/v) and buffer (ph 7–9) is illustrated in figure 3b. the amount of material extracted from the herb is proportional to the initial extract percentage. the proportion of the extractable components in the final extract is directly proportional to the percentage of the original extract; conversely, a low original extract percentage suggests a low percentage of extractable components. the source and amount of an enzyme determine its extraction rate. increasing the volume of the extraction solution may reduce specific enzyme activity because of slow extract production [23]. the results showed a specific enzyme activity of 0.988 u/mg after extraction using 1:8 ratio and sodium phosphate buffer (0.2 m) [17]. the interactions between concentration (0.162–0.2 m) and extraction time (5–28) are shown in figure 3c. the maximum urease activity (3.99 u/mg) was achieved after extraction for 1 hour, which indicated that this time period was ideal for enzyme production. high concentrations of extraction buffer can damage urease activity because it contains too many ionic groups that can prevent enzymes from working [24]. another study found that 0.2 m sodium phosphate buffer (ph 7.5) was the best value to extract urease from cannavalia enciforme. in figure 3e, the ideal extraction conditions were a ratio of 10–15 and an extraction time of 5–28 min. the optimal extraction time for each source of urease enzyme should be determined because of variations in materials present and their potential interferences with the enzyme. moreover, contaminants should be eliminated because they generate a protein extract with a high resistance to decomposition [18]. the present results were higher than those obtained in another work that blended yellow lupine for 120 minutes [25]. figure 4a demonstrates the precision of the model by indicating the close relationship between the forecast derived from the rsm model and the empirical data. figure 4b presents the optimal condition, which includes a ph of 7.99, a buffer concentration of 0.2 m, an extraction ratio of 1:13 and an extraction time of 60 minutes, resulting in a desirability factor of 0.825. these conditions represent the most favourable combination for urease extraction. sarah s. kurdi al-khwarizmi engineering journal, vol. 20, no.3, p.p. 113(2024) 93 (a) (b) (c) (d) (e) fig. 1 3d surface plots for multiple interactive effects on enzyme extraction sarah s. kurdi al-khwarizmi engineering journal, vol. 20, no.3, p.p. 8796 (2024) 94 (a) (b) fig. 2 (a) actual experimental data in comparison with the projected data; (b) results of optimisation analysed using the desirability function. 4. conclusion this study mainly aimed to ascertain the most effective method for isolating urease from chickpea seeds. rsm and ccd were used to implement the experimental design. urease obtained from the seeds of chickpea plants had a high enzyme activity (3.99 u/mg protein) when extracted under the optimal conditions of ph of 7.99, a tris base buffer concentration of 0.2, an extraction time of 60 minutes and a ratio of 1:13 (gm: ml). the experimental data demonstrate a superior level of quality. by employing a second-order polynomial model, our analysis yielded a forecasted correlation coefficient (pred. r2) of 0.8477, an adjusted correlation coefficient (adj. r2) of 0.9333 and a correlation value (r2) of 0.9665. this finding confirms a strong agreement between the anticipated theoretical models and the empirical evidence obtained through experimentation. this method has potential for cost-effective enzyme synthesis through large-scale industrial production and a financially viable alternative to existing methods. references [1] a.m. barrios, and s. j lippard, "interaction of urea with a hydroxide bridged dinuclear nickel centre: an alternative model for the mechanism of urease," j. am. chem.soc, pp. 122: 91729177, 2000. 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(2024) 87-96، صفحة 3، العدد20مجلة الخوارزمي الهندسية المجلد كرديسارة سلمان 96 design expert تحديد الظروف المثلى الستخالص اليورياز من بذور الحمص باستخدام software).) **، مهند جاسم محمد *ساره سلمان كردي العراق بغداد، ،جامعة بغداد، كلية الهندسة ،*.** قسم هندسه البيئة sarhslman1999@gmail.com :البريد االلكتروني* muhannadenviro@yahoo.com:**البريد االلكتروني المستخلص ي وتقيم خواصه مصدر نبات(لتقيم الظروف المثلى الستخالص انزيم اليوريز من rsmهدفت هذه الدراسة الى التحقق من منهجيه سطح االستجابة ) وحدة /ملغم بروتين عند 3.99 ظهرت النتائج ان بذور الحمص امتلك اعلى فعالية انزيمها .الكيموحيوية حيث تم اختيار بذور الحمص كمصدر النزيم اليوريز دقيقه, نسبه 60, زمن من المخزن المؤقت لقاعدة تريس 0.2, تركيز 7.99افضل الظروف استخالص على التوالي ) برقم هايدروجيني (هو 2r .edpr لمتوقع )وبين ان البيانات التجريبه هي افضل تركيبها للنموذج متعدد الحدود من المرتبة الثانية مع عامل االرتباط ا.)غرام:مل(1:13 جريبية هي في اتفاق المتوقعة والقيم التوهذا يدل على ان النماذج 2r 0.9665 وقيم االرتباط 0.9333(هو 2adj. r ,معامل االرتباط المعدل )0.8477 ياًرا إلنتاج الضخم ، مما يجعلها خااإلنزيمات من خالل إضافة إلى ذلك ، تحسين فعالية تكلفة هذه ,وهذه الطريقة واعده ويمكن االستفادة منها في المستقبل .جيد .أكثر جدوى من الناحية االقتصادية مقارنة بالطرق األخرى mailto:sarhslman1999@gmail.com 2. materials and methods table 2 shows the experimental conditions and the results obtained from 25 experiments according to rsm. table 2 design experiment program for maximum enzyme urease extraction (a) (b) [2] dalal subree bedan. "extraction, precipitation and characterization of urease from vicia faba l ".al-mustansiriyah journal of science issn: issn:2521-3520, 2020. [3] j. liu, y. xu, y. nie and g.a. zhao, "optimization production of acid urease by enterobacter sp. in an approach to reduce urea in chinese rice wine," bioprocess biosyst. eng., vol. 35, pp. 651-658, 2012. [4] a.b. becker-ritt, a.h. martinelli, s. mitidieri, v. feder, g.e. wasserman, m.h. vainstein, j.t. oliveira, l.m. fiuza, g. pasqualli and c.r. carlini., "antifungal activity of plant and bacterial ureases.," toxicon, vol. 50, pp. 971-983, 2007. [5] krishna, b.l., singh, a.n., patra, s., and dubey, v.k purification, characterization and immobilization of urease from momordica charantia seeds. process biochemistry, 46 (7), 1486–1491, 2011. [7] qin y, cabral jms: review properties and applications of urease. biocatalys and biotransform 2002, 20(1):1–14. [8] el-hefnawy, m.e., m. sakran, a. ismail, and e.f. aboelfetoh. extraction, purification, kinetic and thermodynamic properties of urease from germinating pisum sativum l. seeds. bmc biochemistry journal. 15:15, 2014. [9] b. hu, k. zhou, y. liu, a. liu and q. zhang, industrial crops and products, 115, 290(2018), doi:10.1016/j.indcrop.2018.02.034. [10] babazadeh, n. s., salehabadi, h., zeidabadi, f., souri, e. and m. amanlou.. study of urease inhibitory activity by medicinal plant extracts based on new catalyst for berthelot reaction and taguchi experimental design. journal of the iranian chemi... [13] yoosefian, m., s. ahmadzadeh, m. aghasi, and m. dolatabadi. optimization of electrocoagulation process for efficient removal of ciprofloxacin antibiotic using iron electrode; kinetic and isotherm studies of adsorption. j. mol. liq. 225: 544– 553,... [17] hussein, s. i., khalaf, a. f., sameh m. a. and m. t. salah. determination of the optimum conditions for urease inhibition extracted from some local plants. iraqi journal of agricultural sciences. 52(4):802-809, 2021. microsoft word ???? ????? ????? al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 17, no. 2, june, (2021) p. p. 1-7 effect of environmental factors on the accuracy of a quality inspection system based on transfer learning ahmed najah* faiz f. mustafa* wisam s. hacham** *,** department of automated manufacturing/ al-khwarizmi college of engineering/ university of baghdad ***department of mechatronics/ al-khwarizmi college of engineering/ university of baghdad *email: ahmednajah5049@gmail.com **email: faizalrawy@yahoo.com ***email: wisam@kecbu.uobaghdad.edu.iq (received 5 october 2020; revised 14 november 2020; accepted 14 december 2020) https://doi.org/10.22153/kej.2021.12.004 abstract in this research, a study is introduced on the effect of several environmental factors on the performance of an already constructed quality inspection system, which was designed using a transfer learning approach based on convolutional neural networks. the system comprised two sets of layers, transferred layers set from an already trained model (densenet121) and a custom classification layers set. it was designed to discriminate between damaged and undamaged helical gears according to the configuration of the gear regardless to its dimensions, and the model showed good performance discriminating between the two products at ideal conditions of high-resolution images. so, this study aimed at testing the system performance at poor settings of lighting, background, distance and camera resolution. experimental results implied that the system was able to show high accuracies above 90% at very bad settings and around 99% at good settings, which assures that an inspection system with good performance can be built at low costs. keywords: convolutional neural networks, densenet121, environmental factors and transfer learning. 1. introduction automated quality inspection systems based on computer vision (cv) and deep learning (dl), can push the manufacturing facilities a step forward, with more accurate, reliable and cost-effective architectures. dl is considered as an advanced data analysis technique and this characteristic places it in a position to be one of the building blocks of smart manufacturing [1]. the importance of using dl with cv on the other hand, has arisen due to several qualities possessed by dl, in which it upscaled traditional cv systems and made it more sophisticated and easier to implement and design. machine vision with deep learning have been used for: defects detection in products [2], inspection of sugarcane varieties [3], process monitoring and quality control [4], welding inspection [5] optical laser welding inspection [6], laser welding defects detection [7] and gear faults diagnosis with convolutional neural networks (cnns) [8]. as dl depends on deep neural networks to extract the necessary features from the data automatically, in contrast with traditional cv techniques where manual features extraction is mandatory [9]. some of the previous researches that relied on traditional cv methods include: inspection of spur gears parameters with the algorithms of cv and image processing [10], measuring gears dimensions with machine vision algorithm [11], detecting defects in welds using cv and machine learning algorithms [12], measuring automobile parts dimensions with machine vision [13], o-rings inspection with cv algorithm [14], aerospace components inspection ahmed najah al-khwarizmi engineering journal, vol. 17, no. 2, p.p. 17 (2021)     2 using cv [15] and anomaly detection in additive manufacturing with cv [16]. unlike conventional manual inspection systems, automated platforms have the advantage of being unaffected by psychological factors and fatigue, which normally occurs with human beings [17]. this characteristic improves the production efficiency and eliminates costs, as continuous operations are performed without being affected by those factors. although, other factors that are not associated with humans emotions like environmental factors, can have major or minor impacts on the system performance depending on the strength of the designed architecture and the training data. so, providing the necessary tools to build a system can help with making it more tolerable to environmental factors. in this paper, a study is conducted regarding the effects of four environmental factors on the performance of a helical gears inspection system that is designed using transfer learning. a number of combined conditions has been used to test and evaluate the system. the remainder of this paper is organized in the following matter, in section two we briefly introduce transfer learning and the built inspection system, in sections three and four; the experimental data and the evaluation results are shown, respectively. finally, we close with section five and six with the conclusions and future work. 2. transfer learning to improve learning within new tasks, knowledge can be transferred from a task that is already learned and related to the new one [18]. that is how transfer learning generally functions. dl and cnns require a massive amount of information about the target task before being able to perform adequately [19]. but, sometimes there are not enough data resources to cover the necessary amount of training data, which results in inaccurate performance by the model, overfitting (high performance on the training data but low on the validation data) [20] and eventually failing to accomplish the target task. so, using a technique like transfer learning can help with eliminating those problems and reducing the amount of requested information. giving a remarkable performance with small datasets and can be compared with custom cnns [21][22]. a previously trained model can be thought of as two sets of tools, one that extracts features and one that classifies the objects according to those features [9]. when transferring layers from one network to another, a new classification layer must be added to classify the new target objects, taking into consideration that the transferred classification layer must be muted. 3. inspection system using transfer learning, a model was designed to detect and classify the helical gears according to their shape condition, densenet121 model was used as the transferred model as can be seen in table 1. the model (fig. 1) was deployed and evaluated on a set of random unseen images with random conditions. evaluation results yielded high classification accuracy, which proved that using cnns with cv was superior to classical methods, as it was easier to implement with automatic features extraction and transfer learning. table 1, inspection system layers. stage layers transferred 1 (conv.) convolution transferred 2 (pooling) max pooling transferred 3 (dense block 1) convolution x 6 convolution transferred 4 (transition 1) convolution average pooling table 1 (continued) transferred 5 (dense block 2) convolution x 12 convolution transferred 6 (transition 2) convolution average pooling transferred 7 (dense block 3) convolution x 24 convolution transferred 8 (transition 3) convolution average pooling transferred 9 (dense block 4) convolution x 16 convolution transferred 10 (classification) global average pooling fully connected to be trained (classification) global average pooling 256d fully connected 50 % dropout 1d sigmoid ahmed najah al-khwarizmi engineering journal, vol. 17, no. 2, p.p. 17 (2021)     3 fig. 1. inspection model architecture.   4. methodology classical analysis methods rely on descriptive type of analysis, which always include hypotheses assembled from the process information patterns, with a comparison between the model results and the genuine results for hypotheses verification [23]. however, models that rely on this method are unsafe, in which some variables might be left unmodeled due to misinterpretation of the issue by the engineers or lack of information [24]. notwithstanding, predictive analysis, takes a phenomenon, unfold the underlying rules and construct a predictive model that takes all the variables into account and restricts errors between the predicted and the desired outcomes [23]. since dl models rely on predictive models, cnns granted an advantage over traditional cv methods as high accuracies for image classification can be guaranteed with automatic feature extraction, where classic cv applications depend on tedious manual features extraction. nevertheless, every model requires some preprocessing steps before performing the target task. so, to conduct the research and study the effects of the previously mentioned factors, few earlier steps were taken to satisfy the prerequisites of the analysis process, which will be briefly discussed in the following subsections. 4.1 data preparation prior to the evaluation process, imagery data of different gears with and without shape damages had to be collected to be classified into two classes, but due to lack of data resources, only two gears were used as the test samples, in which one was used as the healthy class and the other one as the unhealthy (damaged) class. the images for the damaged one were taken at several stages, in which it started with simple damages (surface damage like scratches were not targeted in this research) and then more impairments were added using an electric cutter, as shown in fig. 2. fig. 2. damaged gear during preparation steps. two phone cameras (24 and 8 mega-pixels) were used to capture the test images, moreover, a microcomputer called raspberry pi 3 was also used to collect images by employing an attached camera board with 5 mega-pixels resolution without using any additional lenses, as shown in fig. 3. fig. 3. raspberry pi 3 microcomputer (left) and the camera board (right). ahmed najah al-khwarizmi engineering journal, vol. 17, no. 2, p.p. 17 (2021)     4 jupyter notebook, an open-source development environment, provides the tools to develop deep neural networks and perform the necessary processing operations and data manipulation. so, to study the proposed factors, python’s application programming interface (api) was used within the environment, to build the evaluation code, upload the network and initiate the prediction process. prior to the test, a function was built to convert the inserted images by modifying the dimensions, to meet the densenet121 [25] standard image dimensions of (224 × 224) pixels that it was trained on in the imagenet challenge [26]. then by employing the model as the tool that can classify the images, the accuracy was predicted, and according to the cost function that is used in the model, which is binary cross-entropy function, the loss was also estimated. 4. 2. experimental work the used model was tested with random environmental factors, so, to make sure that the model is fully functional and can be used in real practical applications and industrial facilities, environmental factors must be taken into consideration. factors that were studied within this research are: the intensity of light, the type of background, the resolution of the camera and the distance between the camera and the inspected object. those factors are important to study to select the appropriate settings for the system. as can be seen in fig. 4, a light-box with three 12watts leds was used to take images with different settings of the factors to point out the model capabilities. several images (fig. 5) were captured at different conditions to evaluate the performance of the system. fig. 4. used lightbox for data gathering.   fig. 5. some of the evaluation images. 5. experimental results the effect of the distance factor along with other factors on the system performance is shown in table 2: table 2, illustrates the performance of the used system under different conditions. applied conditions accuracy 24 mega-pixels good lighting 15cm distance 99% 24 mega-pixels poor lighting 15cm distance 96% 8 mega-pixels good lighting 15cm distance 99% 8 mega-pixels poor lighting 15cm distance 92% 5 mega-pixels good lighting 15cm distance 99% 5 mega-pixels poor lighting 15cm distance 85% 5 mega-pixels good lighting 10cm distance 99% 5 mega-pixels poor lighting 10cm distance 90% as it can be seen in table 2, the model showed a good performance discriminating between damaged and undamaged gears. despite the lowresolution cameras that were used like the 5 megapixels camera. different image backgrounds were used during training, consequently; the model ahmed najah al-khwarizmi engineering journal, vol. 17, no. 2, p.p. 17 (2021)     5 classified the object at a high level of certainty despite the different backgrounds, indicating even lesser effect than the camera resolution to no effect at all on the system classification capability. image lighting showed some noticeable effect on the system accuracy with low-resolution images, in contrast to the high resolution images, where lighting showed less effect on the classification accuracy. the distance between the object and the camera was the last studied factor, in which the position of the image capturing device with respect to the position of the inspected object, affects the model accuracy to identify and distinguish between the objects. in essence, the model classification accuracy is proportional to the camera resolution, lighting intensity and the distance, with zero effect from any used background. compared to the lighting, the distance had more effect on the accuracy measures. terms like good lighting and poor lighting refers to the intensity of the light source illumination and how much the object was obvious to the camera, as the better lighting provided the more certain the model would be. good lighting (used lighting) was a minimum of 6.6watt and poor lighting was below that minimum value. briefly stated, the table shows the system performance at its best at each resolution and at the farthest point. 6. conclusions in this paper, a transfer learning-based quality inspection system that was designed to inspect helical gears for faults, was evaluated under the effect of several environmental factors. three cameras with differing resolutions were used to gather the evaluation data, which consisted of ten images at distances of 15cm and 10cm, different backgrounds and poor and good lighting intensities. the system showed good performance adapting to the different conditions, which conveyed the flexibility of the system and the power of cnns. also, this study implies the ability to build a quality inspection system at low costs as cheap setups can be sufficient to fulfil the system requirements. 7. future work this work can be further expanded by studying the effect of the previously 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[26] j. deng, w. dong, r. socher, l.j. li, k. li, and l. feifei, “imagenet: a large-scale hierarchical image database,” ieee conference on computer vision and pattern recognition (cvpr), florida, 2009, pp. 248255.  )2021( 17 صفحة ،2العدد ،17المجلد الهندسية الخوارزمي جلةم احمد نجاح 7 تأثير العوامل البيئية على دقة نظام فحص جودة مبني على التعلم بالنقل ***حجام خضير وسام سعدي** فائز فوزي مصطفى * احمد نجاح | كلية الهندسة الخوارزمي| جامعة بغداد قسم هندسة التصنيع المؤتمت *،** ** قسم هندسة الميكاترونكس| كلية الهندسة الخوارزمي| جامعة بغداد ahmednajah5049@gmail.com :البريد االلكتروني * faizalrawy@yahoo.com**البريد االلكتروني: wisam@kecbu.uobaghdad.edu.iq :البريد االلكتروني*** الخالصة تم إنشاؤه مسبقا، والذي تم تصميمه باستخدام نهج التعلم دراسة حول تأثير عدة عوامل بيئية على أداء نظام فحص الجودة الذي في هذا البحث، تم تقديم ) densenet121بالنقل القائم على الشبكات العصبية التالفيفية. يتألف النظام من مجموعتين من الطبقات، مجموعة طبقات منقولة من نموذج مدرب مسبقا ( يميز بين المنتجين في ظروف لفة، وأظهر النموذج أداًء جيداً لتالفة وغير التاومجموعة طبقات تصنيف خاصه. تم تصميمه للتمييز بين التروس الحلزونية ا مثالية لصور عالية الدقة. أظهرت النتائج التجريبية والخلفية والمسافة ودقة الكاميرا. من األضاءة السيئة الظروف في من هذه الدراسة هو اختبار أداء نظام الفحص ان الهدف الرئيسي ٪ في إعدادات جيدة، مما يضمن إمكانية إنشاء نظام فحص ٩٩٪ في إعدادات سيئة للغاية وحوالي ٩٠النظام كان قادًرا على إظهار دقة عالية أعلى من ن بأ بأداء رائع بتكاليف منخفضة. this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 20, no. 4, december (2024), pp. 1-12 deep learning model for prediction of dementia severity based on eeg signals noor kamal al-qazzaz 1*, sawal hamid bin mohd ali 2,3 siti anom ahmad 4,5 1department of biomedical engineering, al-khwarizmi college of engineering, university of baghdad, baghdad 47146, iraq 2department of electrical, electronic and systems engineering, faculty of engineering and built environment, universiti kebangsaan malaysia, ukm bangi, selangor 43600, malaysia 3centre of advanced electronic and communication engineering, department of electrical, electronic and systems engineering, universiti kebangsaan malaysia, selangor, malaysia, 43600 4department of electrical and electronic engineering, faculty of engineering, universiti putra malaysia, upm serdang, selangor 43400, malaysia 5malaysian research institute on ageing (myageing™), universiti putra malaysia, serdang, selangor 43400, malaysia *corresponding author, s email: noorbme@kecbu.uobaghdad.edu.iq (received 27 march 2024; revised 3 july 2024; accepted 11 august 2024; published 1 december 2024) https://doi.org/10.22153/kej.2024.08.002 abstract this study aimed to determine variations in the electroencephalograms (eegs) of 15 individuals who were diagnosed with mild cognitive impairment (mci) following stroke, 5 individuals suffering from vascular dementia (vd) and 15 healthy normal control (nc) individuals who performed a working memory task. conventional filters including notch and bandpass filters were utilised to remove noise from the eeg data. the proposed method comprises computing the estimates of the attention entropy (atten), bubble entropy (bubben) and symbolic dynamic entropy (sydyen) of univariate data sequence features. the long short-term memory (lstm) deep learning neural network was used to automatically classify dementia severity through noninvasive eeg-based recordings. the lstm classification result with atten exceeds an average of 88.9% than bubben and sydyen, with classification results of 69.2% and 77.7%, respectively. the analysis of the brain eeg-based dementia severity dataset suggests that atten could potentially serve as a biomarker for detecting dementia severity. atten can capture relevant patterns and features in the eeg data and may be indicative of the severity of dementia with lstm rnn to differentiate patients with vd, patients with mci and nc individuals. keywords: dementia; deep learning; transfer learning; long short-term memory; classification 1. introduction cognitive impairment occurs due to vascular lesions that arise from a diverse range of medical conditions, including ischemic heart disease and stroke [1]. about 1% to 4% of the elderly population over the age of 65 years suffers from vascular dementia (vd), and this number will double every 5 to 10 years [2]. vd is the second most common form of dementia, after alzheimer’s disease (ad) [3]. mild cognitive impairment (mci) refers to a decrease in cognitive function that is more severe than one would expect given one’s age and degree of education but does not significantly impact one’s ability to carry out daily tasks [4, 5]. patients diagnosed with mci have a high risk of developing dementia within the third month of the onset of dementia symptoms [3, 6]. this clinical transitional stage occurs between early normal cognition and mailto:noorbme@kecbu.uobaghdad.edu.iq https://doi.org/10.22153/kej.2024.08.002 noor kamal al-qazzaz al-khwarizmi engineering journal, vol. 20, no.4, p.p. 112 (2024) 2 late severe dementia. most people with mci only experience memory loss, but their ability to do daily tasks is unaffected [7]. electroencephalograms (eegs) are used to detect dementia. multiple studies have demonstrated the utility of eegs to identify and assess the severity of dementia [3] as well as differentiate ad from vd and other types of dementia [8, 9,10]. various machine learning classification algorithms have been used to classify eegs of cognitively challenged participants [11]. relative frequencies play a prominent role in each case [12, 13, 14]. however, traditional machine learning approaches are unsuitable for processing highdimensional volumes of data because they are based on the explicit definition of features. deep learning is a cutting-edge machine learning technology that can address those drawbacks and has an advantage over traditional machine learning techniques; deep neural networks (nns) can process and learn latent discriminative features from raw data or end-to-end learning. deep learning-powered ad detection systems have emerged given that deep learning has been proven to have many real-world applications, such as in biomedicine [15, 16] and image detection [17, 18]. the majority of these systems rely on neuroimaging analysis (structural and functional magnetic resonance imaging or smri and fmri, respectively), with data from the ad neuroimaging initiative (adni) database. very few deep learning studies have focused on the differentiation of ad by using eeg recordings [19]. given the nonlinearity and complexity of biological systems, scholars have suggested alternative entropy measures to characterise eeg signals [20, 21]. the approximate entropy (apen) algorithm derives a measure of entropy for noisy biomedical time series that is statistically valid. this measure represents the likelihood that time series patterns that are similar at first glance will retain their similarity even after the pattern lengths are increased. as such, this algorithm offers an inherent assessment of the regularity of time series [22]. nevertheless, previous research demonstrated that apen is a highly sensitive estimator that is skewed by the number of data samples [23]. sample entropy (sampen), an adaptation of apen, excludes self-matches from the probability calculation [24]. a reduced value of sampen signifies increased self-similarity within the time series. sampen exhibits greater consistency in its behaviour and is more independent of data samples than apen [24]. however, sampen possesses certain limitations, such as potential instability and unreliable results when applied to brief time series [25]. fuzzy entropy (fuzen) employs the notion of fuzzy sets to address limitations associated with sample entropy. fuzen exhibits a more robust relative consistency and reduced reliance on data length than sampen [25]. additionally, continuity is ensured by the continuous and flexible boundaries of fuzzy functions. however, the degree of freedom associated with selecting internal parameters is greater than that of sample entropy because of the introduction of fuzzy power and membership function to delineate the boundary [26]. determining internal parameters is a crucial aspect of obtaining entropy metrics. manis et al. proposed bubble entropy (bubben), a new definition of entropy derived from permutation entropy (peren) that ranks vectors in the embedding space of the time series [27]. the effort from the number of exchanges is quantified for permutation, which is executed via the ‘bubble sort’ algorithm. bubble entropy is virtually devoid of internal parameters; its definition completely omits the scaling factor 𝑟, and the significance of embedding dimension m is drastically diminished [27]. in general, symbolism can increase performance in characterisation and quantification of time series [28]. time series representation depends on the method of delay time on the scheme introduced by tekens for phase space reconstruction. methods for state space reconstruction rely on the detection of lags of some degree of independence (linear or nonlinear); signal strength has been used as a statistical tool to determine the presence of dependence in time series [29]. symbolic dynamics entropy (sydyen) is a convenient tool for selecting the optimal state space reconstruction parameters for chaotic time series. thus, having defined the symbolic properties of the problem, we then used the entropy measure associated with the symbolic space (symbolic entropy) for parameter selection [29]. the attention entropy (atten) approach has been innovated to isolate the most critical observations and measure their frequency of prevalence within the time series. the model may cognizance at the time steps that have maximum information but ignore those that are too noisy. this approach has improved typical performance and resistance to noisy inputs [30]. in the realm of deep learning, models such as 1d-convolutional neural networks (cnns) [31] and cnns [32, 33, 15] are common. cnns provide many benefits, such as speed, accuracy and power when processing visual data, huge amounts of data, and complex pattern predictions. however, cnns noor kamal al-qazzaz al-khwarizmi engineering journal, vol. 20, no.4, p.p. 112 (2024) 3 need labelled data and have high computational cost of training, and their predictions are difficult to confirm. different types of nns have been employed for signal classification, including rnns [34, 35] and lstms [36, 37, 38] for eeg and other critical signal processing. rnns and lstm can handle data of varying lengths, catch patterns across time and integrate complex nn designs. regular neural networks (rnns) have a lot of drawbacks, such as a high computing cost, lengthy training durations and problems with bigger datasets. every approach has its advantages and disadvantages, so selecting a suitable method depends on the type of problem and the level of precision needed. this study could provide insights into dementia. patients with dementia frequently exhibit diminished nonlinear cell dynamics and/or nonlinear coupling within the brain cortex as well as linear couplings. these factors can result in a decline in complexity and functional connections. to comprehend this phenomenon, scholars should investigate the nonlinear eeg dynamics of patients with dementia. in the early stages of dementia, eegs may appear normal and have the same rhythm as healthy individuals of the same age. eeg recordings obtained from individuals with dementia should be analysed and interpreted using signal analysis techniques to assess the influence of dementia on the brain and understand the progression of the disease [5]. this study aimed to determine if individuals have vd, mci, or normal control (nc) condition by using deep learning recurrent neural networks. the features of univariate eeg data sequences should be estimated using attention entropy (atten), bubble entropy (bubben) and symbolic dynamic entropy (sydyen). the long short-term memory (lstm) deep learning neural network was used to discriminate dementia severity. this study aims to develop a paradigm that could be used in real-world clinical settings and classify patients as having vd, mci, or nc based on noninvasive scalp eeg recordings. 2. materials and methods the recorded eegs would go through a series of signal processing stages designed to separate the symptoms of patients with dementia to diagnose post-stroke clinical manifestations. fig. 1 shows the flowchart of the proposed method. fig. 1. flowchart of the proposed method. 2.1 subjects and eeg recording procedure the eeg datasets of 15 nc individuals (aged 60.06±5.21) years), 15 patients (aged 60.26±7.77 years) with mci due to stroke and 5 people with vd (aged 64.6±4.8 years). healthy volunteers had no known history of mental disorders. patients suffering from stroke were culled from the stroke ward at pusat perubatan universiti kebangsaan malaysia hospital. the groups were evaluated cognitively by using the mini-mental state examination (mmse) [39] and montreal cognitive assessment (moca) [40]. the hospital human ethics committee gave their approval to all of the noor kamal al-qazzaz al-khwarizmi engineering journal, vol. 20, no.4, p.p. 112 (2024) 4 experiment protocols. all participants also signed an information consent (icf) form. nicoletone (v32) systems were used to record eeg activities. in accordance with the 10-20 international system, 19 electrodes, including the ground and system reference electrodes, were placed (fp1, fp2, f7, f3, fz, f4, f8, t3, t5, t4, t6, p3, pz, p4, c3, cz, c4, o1 and o2). in this study, all participants engaged in an auditory working memory (wm) task session. as the subjects were instructed to relax completely, an auditory session began with a 0.5-second fixation cue. the participants were then given a brief wm test, during which they were asked to memorise five words for 10 seconds. the participants were then asked to try to recall the words while keeping their eyes closed, and eeg data were collected. they closed their eyes for 60 seconds, opened them and list as many words as they could remember [8]. 2.2 preprocessing stage in the first step of processing each channel of recorded eeg datasets, conventional filters were used; in particular, a notch filter at 50 hz was used to remove interference noise, and a bandpass filter with a (0.5–64) hz frequency range was used to limit the band of the recorded eeg signals [41, 42]. 2.3 feature extraction stage the eeg signals for all channels were segmented into nonoverlapping windows of 2 s for feature extraction. entropy features including attention entropy (atten) [38], bubble entropy (bubben) [43] and symbolic dynamic entropy (sydyen) [44, 45, 46] of univariate data sequence features were extracted. the dimension of each feature vector from each subject was equal to 30 windows × 19 eeg channels. patients with vd were a minority in this research. synthetic oversampling technique (smote) was utilised to rectify the data imbalance [47]. empirical evidence is lacking to support the efficacy of bubben or dispen in the characterisation of eeg signals. the present work aimed to assess the discriminatory capability of atten, bubben and sydyen in discerning the severity of dementia based on eeg signals a. symbolic dynamic entropy (sydyen) symbolic dynamics evaluates dynamical systems based on the proper partitioning of the symbol sequences obtained for the state space. symbolic dynamic entropy (sydyen) is based on an entropy unit. simple methods can preserve some important properties of the dynamics, such as periodicity and dependence, despite the loss of a certain amount of detail. symbolic dynamics (sde) has been used to locate dynamics in nonlinear systems [48, 49, 50, 51]. to apply the sydyen approach, the time series must first be transformed into a symbolic series, 𝑋 = 𝑥1, 𝑥2, 𝑥3, . . . , 𝑥𝑛, which represents a time series of length n. one way to transform time series into symbolic time series is by using maximum entropy partitioning, which offers adaptive segmentation [45]. in the equation, λ stands for the time delay and m for the embedding dimension in the symbolic time series. the next step is to determine the probability of state transitions [52]. equation 1 defines the sde in accordance with the theorem of shannon entropy. 𝑆𝐷𝐸(𝑋, 𝜇, 𝑚, 𝜆) = − ∑ 𝑃(𝑞𝑎 𝜇,𝑚,𝜆 )𝑙𝑛𝑃(𝑞𝑎 𝜇,𝑚,𝜆 ) 𝜇𝑚 𝑎=1 − ∑ ∑ 𝑃(𝑞𝑎 𝜇,𝑚,𝜆 )𝑙𝑛𝑃(𝑞𝑎 𝜇,𝑚,𝜆 ) 𝜇𝑚 𝑎=1 𝜇 𝑎=1 𝑃(𝜎𝑏|𝑞𝑎 𝜇,𝑚,𝜆 ) …(1) ) lastly, the sde is adjusted to ensure that it follows the normal distribution with 0 < sydy < 1, as shown in equation 2. 𝑆𝑦𝐷𝑦𝐸(�̅�, 𝜇, 𝑚, 𝜆) = 𝑆𝐷𝐸(�̅�, 𝜇, 𝑚,/ ln(𝜇𝑚+1) …(2) b. bubble entropy (bubben) manis et al. [43] suggested the use of bubben to differentiate congestive heart failure from a healthy control group. the bubben formula is an adaptation of the permutation entropy that incorporates elements from the permutation entropy and the renyi entropy as well as some additional terms from the apen [53]. the number of swaps needed to sort a vector x½i is counted in bubben, which uses the bubble sort algorithm. its discriminatory power is independent of input parameters, thus it is almost a parameter-free entropy [43]. these are the steps involved in the calculation: first, for a certain system x, the entropy may be determined by equations 3 and 4. 𝐻𝑎 𝑚(𝑋) = 1 𝛼 log(∑ 𝑃𝑖 𝑎 𝑛 𝑖=1 ) …(3) 𝐻2 𝑚(𝑋) = − log(∑ 𝑃𝑖 2 𝑛 𝑖=1 ) …(4) the renyi entropy, also known as the generalised entropy, is obtained as shannon entropy when α → 1. in this paper, we take α = 2 to obtain equation 4, so that the peaks and mutation points in the noor kamal al-qazzaz al-khwarizmi engineering journal, vol. 20, no.4, p.p. 112 (2024) 5 sequence can be well described and the effect of chance is not overly weakened. the following step makes m increases 1 and calculation like equation 4 and gain . bubben can be obtained from equation 5. 𝐵𝑢𝑏𝑏𝐸𝑛(𝑋, 𝑚)) = 𝐻2 𝑚+1 − 𝐻2 𝑚 log 𝑚 + 1 𝑚 − 1 …(5) sequence rearrangement using the traditional sorting method solely takes the original sequence’s size order into account and ignores the effect of amplitude differences. symbolisation cannot assign unique alignment to subsequences containing components of the same size; for instance, the sequence (2,1,2) can be assigned to both (1,0,2) and (1,2,0). this assignment method will, to some extent, cause the important information to be ignored. when it comes to parameter selection, bubble entropy is optimised for reducing the model’s dependence on input parameters (such as data length or embedding size) by calculating the number of sample exchanges needed to generate an ordered subsequence instead of counting the ordered pattern [43]. c. attention entropy (atten) entropy methods are sensitive to parameter settings, but atten focuses only on observations of key features. instead of counting all observation frequencies, it finds the frequency distribution interval between key observations in a time series. the advantage of atten is that it does not need any parameters to tune, it is robust to long time series and requires only linear data when calculating atten. the calculation can be done in three basic steps [30]: to define the basic model, to calculate the distance between two adjacent principal patterns and to compute the shannon entropy of the intervals. the difference between classical entropy methods and attention entropy methods involves classical frequency-based entropy methods, which cannot separate two chains because both models have the same frequency distribution. in atten, the distribution of distances between key patterns in the chain is different [30, 55]. three primary procedures are used to determine attention entropy (atten). key patterns are defined, intervals between adjacent key patterns are calculated and the shannon entropy of intervals is computed. classical frequency-based entropy algorithms are unable to distinguish between the series 1 and 2 because of the identical pattern distribution. the interval distributions of the series’ key patterns are different. atten can accomplish this. primarily, we establish the key pattern ω when we are given a finite series 𝑋. secondly, for every sub-series ui, uk and uj of 𝑋 that do not match in for any 𝑖𝑗 , 𝑘𝑗 we determine the intervals 𝐼ω − 𝜐|𝜐 − 𝑗 − 𝑖 by comparing 𝑢𝑖 and 𝑢𝑗 to the pattern ω. attention entropy, or shannon entropy over iv, is computed [30]. dementia classification using lstm model the deep learning method represented by the lstm network was used for eeg-based signal dementia classification. lstm [56] is a type of recurrent neural network (rnn) used in many biomedical indications to detect unidirectional durationdependent time steps between time series or continuous data [57, 58]. this study reports the first use of lstm to classify eeg-based symptoms of dementia. after implementing the lstm model and validating it using selected eeg features, the model design adopted for this study consisted of a layer of 200 hidden in the layered architecture of the implemented lstm model batch normalisation, improved linear unit (relu) layer, ending with a fully connected level (the number of nodes is equal to the number of severe dementia groups) and a softmax activation level for segmentation. optimal moment calculation for training ”adam” solver, gradient threshold 1, maximum number of 64 epochs and 8 small batch size. optimisation was performed in matlab r2023b. the dataset was divided into the training, validation and testing datasets at a ratio of 70:15:15. splitting the dataset in this manner can provide sufficient data for model development; however, we made sure to have good validation and test datasets for model validation and hyperparameter selection. 2.4 dementia classification using lstm model the deep learning method represented by the lstm network was used for eeg-based signal dementia classification. lstm [56] is a type of recurrent neural network (rnn) used in many biomedical indications to detect unidirectional duration-dependent time steps between time series or continuous data [57, 58]. this study reports the first use of lstm to classify eeg-based symptoms of dementia severity. by implementing the lstm model and validating it using selected eeg features, the model design adopted for this study consisted of a layer of 200 hidden in the layered architecture of the implemented lstm model batch normalisation, improved linear unit (relu) layer, ending with a fully connected level (the number of nodes is equal to the number of severe dementia groups) and a noor kamal al-qazzaz al-khwarizmi engineering journal, vol. 20, no.4, p.p. 112 (2024) 6 softmax activation level for segmentation. optimal moment calculation for training ‘adam’ solver, gradient threshold 1, maximum number of 64 epochs and 8 small batch size. optimisation was performed in matlab r2023b. the dataset was divided into the training, validation, and testing datasets at the ratio of 70:15:15. splitting the data in this manner can provide sufficient data for model development; however, we made sure to have good validation and test datasets for model validation and hyperparameter selection. 3. results and discussion the results of the conventional filters on channel 'fp1' are illustrated in fig. 2. compared with the original recorded eeg (dashed black colour), the artifactual components were effectively and sufficiently suppressed (blue colour). fig. 2. preprocessing results of eeg ch1, which represents fp1, following the application of conventional filters. as demonstrated in figs. 3, 4 and 5, a confusion matrix was used to assess the classifier’s effectiveness in categorising vd (class1), mci (class 2) and nc (class3) occurrences. the projected classes are shown in the rows of the matrix, and the actual classes are shown in the columns. the number of examples that were successfully identified is represented by the diagonal elements, which show the classifier’s accuracy for each class. fig. 3 shows the confusion matrix of the classification results of the lstm model obtained using sydyen, which successfully distinguished between vd and nc cases, as shown by the zero false positive and negative numbers for mci, indicating a high accuracy of 100%. however, the classifier cannot correctly categorise nc (accuracy of 66.7%) and vd (accuracy of 75%). the confusion matrix shows that the lstm model with sydyen achieves a total classification accuracy of 77.8%. the sydyen’s inability to close this performance difference raises concerns about its ability to distinguish between vd, mci and nc classes, either because its features are too complicated or too comparable. investigating the bubben feature might be essential to improve the classifier’s capacity to correctly categorise vd, mci and nc groups. fig. 3. confusion matrix of the classification results for the lstm model using sydyen. the classification results for the lstm model with bubben are shown in fig. 4. we obtained 69.2% rate of correct classifications. although 80% of vd cases are accurately identified as vd, 7.7% noor kamal al-qazzaz al-khwarizmi engineering journal, vol. 20, no.4, p.p. 112 (2024) 7 are mistakenly labelled as nc. meanwhile, 50% of nc cases were wrongly forecasted as mci, and 100% of mci cases were accurately categorised. fig. 4. confusion matrix of the classification results for the lstm model using bubben. to address the discrimination based on dementia severity, further research was conducted using the atten feature in conjunction with lstm. the results of using atten improved the classification accuracy to 88.9% (fig. 5). after applying the atten feature, the three diagonal cells display the proportion of correct lstm classification. for vd, the correct classification was 100%. all individuals with mci due to stroke were appropriately categorised as such, 75% as non-concussional (nc) subjects and 25% as misclassified patients with mci. fig. 5. confusion matrix of the classification results for the lstm model using atten. in this study, new methods have been proposed to diagnose people with vd, mci as a result of a stroke or nc by using eeg data and lstm deep learning. the findings of this research can be summarised as follows. the lstm deep learning model using the atten feature obtained the highest average classification accuracy of 88.9% and thus presented better results than sydyen and bubben. table 1 shows that the results are consistent with other benchmark studies [31, 32, 33, 15, 34, 35] and that the lstm feature that made use of the atten yielded good classification rates. to the best of our knowledge, our work is the first to propose a set of novel features based on entropy to differentiate between mci, vd and nc based on eeg data. the superior performance in the atten feature can be attributed to the desirable characteristics of the temporal analysis of the eeg signals and the presence of attention-related features that are affected in conditions such as ad and dementia. the lstm model’s utilisation of such hinges on its overall performance in learning and modelling complex temporal patterns, contributing to high levels of classification. this investigation has several limitations; for example, the study has a limited number of participants, especially in the vd category. for future work, researchers should replicate the findings with larger and more varied data to ensure the robustness of the method. moreover, they should implement the proposed approach in clinical practice scenarios. the findings revealed in our study provide evidence that deep learning-based methods integrated with newly proposed eeg features can be effectively used to distinguish between mci, vd and nc groups. the presented study adds to the current knowledge about identifying cognitive decline in memory and dementia by employing neurophysiological markers. noor kamal al-qazzaz al-khwarizmi engineering journal, vol. 20, no.4, p.p. 112 (2024) 8 table 1, comparison of our findings to relevant studies in the literature. study algorithm accuracy (%) klepl et al. [31] adaptive gated graph cnn 90.2 shikalgar et al. [32] hybrid deep learning 93.3 fouladi et al. [33] efficient deep neural networks 92.5 huggins et al. [15] deep learning 84.2 alessandrini et al. [34] lstm 91.2 amini et al. 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(2024) 1-12، صفحة 4، العدد20مجلة الخوارزمي الهندسية المجلد نور كمال القزاز 12 تخطيط الدماغ الخرف من إشاراتنموذج التعلم العميق للتنبؤ بشدة 5،4يتي أنوم أحمد ، س3،2*، شوال حميد بن محمد علي1نور كمال القزاز قسم الهندسة الطبية الحيوية، كلية الخوارزمي للهندسة، جامعة بغداد، بغداد ، العراق1 سيالنغور، ماليزيا قسم الهندسة الكهربائية واإللكترونية والنظم، كلية الهندسة والبيئة المبنية، جامعة كيبانغسان ماليزيا، 2 سيالنغور، ماليزياا، مركز الهندسة اإللكترونية وهندسة االتصاالت المتقدمة، قسم الهندسة الكهربائية واإللكترونية وهندسة النظم، جامعة كيبانغسان، ماليزي 3 قسم الهندسة الكهربائية واإللكترونية، كلية الهندسة، جامعة بوترا ماليزيا، سيالنغور، ماليزيا 4 5 المعهد الماليزي لبحوث الشيخوخة ، جامعة بوترا ماليزيا، سيردانغ، سيالنغور، ماليزيا noobme@kecbu.uobaghdad.edu.iq*البريد االلكتروني: الخالصة ( بعد السكتة mciفرًدا تم تشخيص ضعفهم اإلدراكي الخفيف ) 15( لـ eegsتهدف هذه الدراسة إلى تحديد االختالفات في مخطط كهربية الدماغ ) ( الذين كانوا يؤدون مهمة الذاكرة ncشخًصا يتمتعون بصحة جيدة. التحكم الطبيعي ) 15(، و vdمن الخرف الوعائي )أفراد كانوا يعانون 5الدماغية، و . تشمل الطريقة المقترحة حساب eeg(. تم استخدام المرشحات التقليدية بما في ذلك مرشحات الشق والعصابة إلزالة الضوضاء من بيانات wmالعاملة ) ( لميزات تسلسل البيانات األحادية. تستخدم sydyen( واالنتروبيا الديناميكية الرمزية )bubben(، وإنتروبيا الفقاعة )attenنتباه )تقديرات إنتروبيا اال ئمة ( لتصنيف شدة مرضى الخرف تلقائيًا من خالل التسجيالت غير الغازية القاlstmهذه الدراسة الشبكة العصبية للتعلم العميق للذاكرة طويلة المدى ) sydyenو bubben٪ من منتجات 88.9متوسط attenمع lstmعلى تخطيط كهربية الدماغ. من حيث دقة التصنيف، تتجاوز نتائج تصنيف ٪ على التوالي. بناًء على تحليل مجموعة بيانات شدة الخرف القائمة على تخطيط دماغ الدماغ، تشير 77.7٪ و 69.2المستخدمة األخرى بنتائج تصنيف eegالقدرة على التقاط األنماط والميزات ذات الصلة في attenيمكن أن يكون بمثابة عالمة حيوية الكتشاف شدة الخرف. لدى attenتائج إلى أن الن ، وقد يكون فعااًل في تحديد cnوالمشاركين في mciو vdللتمييز بشكل أفضل بين مرضى lstm rnnوقد يكون مؤشًرا على شدة الخرف مع .mciو vdضى الذين يعانون من المر mailto:noobme@kecbu.uobaghdad.edu.iq abstract 1. introduction 2. materials and methods 2.1 subjects and eeg recording procedure 2.2 preprocessing stage 2.3 feature extraction stage 2.4 dementia classification using lstm model 3. results and discussion 4. conclusion references this is an open access article under the cc by license : improving barcode vision scanning process using a drone-based tracking pid controller for warehouse in industry 4.0 samer al-hamadani1*, izzat al-darraji2 and houssem jerbi3 1, 2department of automated manufacturing ,al-khwarizmi college of engineering, university of baghdad, baghdad, iraq 3department of industrial engineering, college of engineering, university of hail, saudi arabia samer.razaq2204@kecbu.uobaghdad.edu.iqcorresponding author’s email: (received: 23 may 2024; revised: april 2024; accepted: 10 november 2024; published: 1 june 2025) https://doi.org/10.22153/kej.2025.11.002 abstract drones play a vital role in the fundamental aspects of industry 4.0 by converting conventional warehouses into intelligent ones, particularly in the realm of barcode scanning. various potential issues frequently arise during barcode scanning by drones, specifically when the drone camera has difficulty obtaining distinct images due to certain factors, such as distance, capturing the image whilst flying, noise in the environment and different barcode dimensions. in addressing these challenges, this study proposes an approach that combines a proportional–integral–derivative (pid) controller with image processing techniques. the pid controller is responsible for continuously monitoring the camera’s input, detecting the difference between the planned and the real barcode image dimensions, and making immediate changes to the drone position to improve the process of detecting the potential barcode. the aforementioned procedure is implemented on the dji tello drone to verify the practical performance of the methodology introduced in this study. results showed that drones can achieve remarkable barcode scanning performance by incorporating sophisticated computer vision technologies into pid controllers. pid computer vision algorithms are capable of analysing visual data acquired from the drone’s cameras and retrieving barcode information under a variety of situations, such as the size of the barcode, location of the barcode and noise of the warehouse environment. keywords: drone; barcode scanning; vision camera; pid controller; warehouse; industry 4.0 1. introduction drones, a type of unmanned aerial vehicles (uavs), are essential in several civil and military uses where they are becoming increasingly popular due to their versatility and ability to explore remote areas [1]-[5]. moreover, drones are equipped with cameras, sensors and other tools that allow them to autonomously perform various tasks. recently, drones have gained significant technological importance and become a crucial element of modern progress, substantially modernising several industries toward industry 4.0. the incorporation of modern technologies, such as the internet of things (iot) and artificial intelligence (ai), in industry 4.0 improved industrial processes by increasing flexibility. consequently, production increased, and product quality improved [6]-[9]. for instance, the implementation of industry 4.0 at the hannover messe in 2011 resulted in substantial transformations in industrial infrastructure and logistical operations. industry 4.0 plays a crucial role in supply chain management by transforming it into an intelligent system and enhancing its agility. iot is a fundamental component of industry 4.0 where effectively managing warehouse inventory is a crucial aspect of supply chain management [10]. currently, the field of logistics is experiencing significant application in russia and across the world. an estimation of the inventory velocity using a quadcopter was conducted, along with an evaluation of the available solutions in the market al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818–1171, issn (online): 2312–0789 vol. 21, no. 2, june (2025), pp. 72–92 mailto:samer.razaq2204@kecbu.uobaghdad.edu.iq https://doi.org/10.22153/kej.2025.11.002 samer al-hamadani al-khwarizmi engineering journal, vol. 21, no.2, pp. 72-92 (2025) 73 [11]-[14]. drones can automate a variety of warehouse duties, such as the evaluation and inspection of inventory, the execution of orders and surveillance [15]-[17]. furthermore, drones are excellent candidates for usage in applications, such as inventory checking in huge warehouses. given that drones are flexible enough to navigate the restricted warehouse corridors, they make it easy to reach the towering racks. drones can not only carry the sensors needed for warehouse inspection but also maintain flight for extended periods [18]. the dji tello drone is extensively utilised as an instructional platform in the domain of control engineering. this device provides an affordable and small-scale option for performing research in laboratory environments where gps signals are unavailable [19]. the drone’s hardware and software design, together with its mathematical model, have been described in academic articles, demonstrating its potential as an experimental platform. students and young scientists have utilised drones in a range of studies, including trajectory generation and person detection and tracking [20]. the utilisation of drones in control engineering courses has offered important practical experience and enhanced comprehension of fundamental principles [21]. although drones are inexpensive, they have demonstrated impressive performance and have been effectively utilised in laboratory practice courses and advanced control projects [22]. the term ‘drone’ has gained significant prominence in the logistics industry in recent years. drone deliveries offer a dual benefit by potentially reducing delivery time by bypassing road congestion and having an intrinsic design that minimises its carbon footprint compared with conventional transportation methods, subject to certain limitations. several firms worldwide have designed and evaluated drones for practical use to exploit this potential [23]. an intermediate is required to facilitate data transmission and information retrieval from inventory using a drone. this intermediary should provide product information in a digital format that can be easily accessed by the drone. the barcode system serves as an effective solution for this purpose. the simplicity and effectiveness of the barcode system demonstrate its ability to effectively eliminate data entry errors and enhances data entry efficiency at a low cost [24]. barcodes efficiently manage storage by creating an inventory of items and recording their locations. furthermore, barcodes are finite multisets of intervals on the real line that summarise the persistent homology groups of filtrations in topological data analysis [25], [26]. the field of barcode recognition and analysis has attracted significant interest in academic and commercial spheres. barcodes are widely recognised as the fundamental element of supply chain management due to their notable benefits, such as their strong dependability and low cost [27]. in the last decade, barcodes have been extensively utilised. a key factor in this phenomenon is the utilisation of sophisticated technology, such as radio frequency identification (rfid), which is highly complex and entails substantial initial capital expenditures, including the costs of tags, readers and software systems [28], [29]. since the introduction of barcodes, they have gained significant attention due to their large storage capacity, enhanced security, durability and various other features. consequently, barcodes are likely to remain in use in the foreseeable future [30], [31]. inventory management in large warehouses involves challenges related to precision, time allocation and potential hazards. in the context of large-scale inventory management, the use of traditional portable barcode scanners poses difficulties as every barcode must be manually scanned, requiring significant human labour. the utilisation of computer vision technology for barcode reading enhances productivity in conducting large-scale scanning operations in vast warehouses [32], [33]. the extensive utilisation of drones has made a substantial contribution to several applications, such as natural resource management [34] and warehouse inventory management [31]. in addition, warehouses are progressively utilising drones equipped with cameras for a variety of functions in operational oversight. these applications encompass inventory verification and visual response. drone cameras are capable of capturing static pictures for further analysis or providing live video feeds for monitoring from a first-person perspective. this approach enables a rapid and effective inventory verification of goods and objects within the warehouse [35], [36]. warehouse inventory management is optimised through the utilisation of drones equipped with barcode scanners that use advanced camera technology. consequently, barcode scanning-based drones are crucial in modern logistics and inventory management systems. nevertheless, obstacles frequently arise during barcode scanning, particularly when the camera struggles to capture distinct pictures due to factors, such as distance, diverse barcode dimensions or when the barcode is positioned at an angle due to the box’s movement. when utilised with drones, barcode scanning samer al-hamadani al-khwarizmi engineering journal, vol. 21, no.2, pp. 72-92 (2025) 74 systems typically face challenges that prevent the consistent collection of data. significant challenges must be overcome in barcode detection, including drone movement, vibrations and varying light conditions. this study proposes a strategy that leverages the capabilities of a proportional– integral–derivative (pid) controller in conjunction with an image scanning method to address these challenges. the pid controller is responsible for continually monitoring the input from the camera, recognising any variations between the intended and actual barcode picture, and making rapid modifications to optimise the camera’s performance. this approach is used to accomplish these tasks. 2. methodology in this study, barcode scanning and the pid controller are integrated into a single algorithm to enhance barcode scanning by drone. the versatility of the algorithm makes it a promising solution for improving barcode scanning across various logistics and inventory management settings. 2.1 barcode scanning computer vision has an extensive and wellestablished history spanning several decades. this field focuses on altering and examining digital images using different algorithms and methods to extract meaningful information [37], [38]. image processing almost involves one or more of the following techniques: mathematical operations, filters or modifications on an image to enhance its quality, extract important information or achieve specific goals, such as object detection or recognition [39], [40]. the advancement of methodologies that enable computer systems to interpret and evaluate visual data closely parallels human interaction with their own vision. this development pertains to the progress in comprehending pictures and movies, demonstrating the broad areas of computer vision. computer vision is an essential and versatile technology in robotics, allowing for tasks, such as measuring and placement [41]. specifically, computer vision functions as the primary sensory mechanism utilised in drones to collect information on the immediate environments [42]. meanwhile, barcode advancements, along with advanced computer vision technology, provide several advantages for drone applications. barcode scanning is essential in areas, such as transportation, inventory management and retail, where precise and rapid data collection is of utmost importance. the need for enhanced efficiency and precision in data collection can be addressed by improving barcode recognition skills in drone applications. however, the purpose of creating barcodes was to make a 1d european article number (ean) barcode. the ean barcode is a well-recognised method used for product identification, extensively utilised in europe and several international markets. the ean barcode consists of 13 digits and encodes information, such as country, manufacturer and product codes. the structure of the ean-13 barcodes (figure 1) consists of the following elements [43]: • the number system refers to the initial two digits of the ean number, which are used to identify the numbering authority of a nation or region. • the manufacturer code is a unique code assigned to each manufacturer by the numbering authority indicated by the number system code. every product manufactured by a certain business will share a common manufacturer code. • the manufacturer assigns the product code. the product code directly follows the manufacturer code. the combined length of the manufacturer and product codes must be exactly 10 digits. • the check digit serves to validate the accuracy of barcode generation or scanning. this digit is derived from the remaining digits of the barcode using a calculation process. fig. 1. ena-13 barcode structure this method guarantees the creation of ean barcodes whilst following the defined format and incorporating crucial product details. the aforementioned actions are executed by controlling the drone and managing its functions whilst also generating barcodes using python. python has been samer al-hamadani al-khwarizmi engineering journal, vol. 21, no.2, pp. 72-92 (2025) 75 chosen due to its broad capabilities, libraries, ease of programming and ability to deliver good results. drone control involves the use of the opencv library to perform remarkable image and video processing through the drone’s camera. once a barcode is captured, it is promptly decoded and instantaneously read by using the pyzbar library. pyzbar is a python package developed by l. hudson [44] that provides an interface for decoding barcodes and extracting information from video files captured by the drone camera via the ovc library. the pyzbar library works by analysing video frames and identifying areas that may contain a high frequency of barcodes. thereafter, this library processes these regions to extract barcode data. the library provides functions to easily integrate barcode decoding into python applications. pyzbar allows the decoding of various types of barcodes, including qr codes and ean-13. this library provides correct reading and decoding ratios for barcodes with a detection rate of up to 95% [45]. 2.2 pid controller the pid controller is typically regarded as the predominant control technology in control applications, providing robust and dependable performance for most systems. this controller is extensively used in various applications is due to its simplicity and resilient framework in different operational environments [46]-[50]. the pid controller comprises three main parameters, namely, proportional (k_p), integral (k_i) and derivative (k_d). several conventional techniques exist for adjusting pid parameters, including the trial-and-error method and ziegler–nichol’s method. the commonly used approach is the ‘manual tuning’ method [51]-[53]. in this study, the pid controller is paired with computer vision to improve the accuracy of barcode scanning by drones, as mentioned in section 3.1. figure 2 illustrates the block diagram of the pid controller used in this study, where the pid controller enables the dji tello drone to stop upon correctly capturing the barcode of the potential product. hence, this pid controller is designed to regulate the required barcode area in terms of pixels. r_b represents the required value of the barcode area in terms of pixels. meanwhile, a_b is the actual value of the barcode area, which is obtained from the camera of the dji tello drone in the scanning process. fig. 2. pid controller block diagram of the dji tello drone in the scanning process for instance, the area pixel of the barcode shown in figure 3 during the dji tello drone scanning process was around 15,000 pixels, allowing the barcode to be read. consequently, r_b in figure 3 is equal to 15,000. meanwhile, a_b represents the current and actual value of the area scanned by a drone camera. when the a_b reaches r_b, the drone will immediately stop, and the barcode will be detected. fig. 3. barcode of the potential product integration of the pid controller with computer vision enhances the drone vision system by adjusting the dji tello drone position to ensure effective barcode scanning. the pid controller utilises real-time data on the barcode rectangular area, measured in pixel values from the computer vision system, to precisely regulate the drone’s distance to the position of the barcode to guarantee precise and efficient barcode scanning. consequently, the pid controller ensures accurate distance tracking between the dji tello drone and the barcode, whilst the computer vision (section 3.1) utilises a barcode recognition algorithm that instantly identifies and decodes barcodes with improved accuracy. the pid controller-based image processing is expressed in equation (1) as follows: 𝑈𝑏𝑎(𝑡) = 𝐾𝑝𝑒𝑟𝑟𝑑(𝑡) + 𝐾𝑖 ∫ 𝑒𝑟𝑟𝑑(𝑡)𝑑𝑡 + 𝐾𝑑 𝑑𝑒𝑟𝑟𝑑(𝑡) 𝑑𝑡 𝑡 0 , samer al-hamadani al-khwarizmi engineering journal, vol. 21, no.2, pp. 72-92 (2025) 76 ...(1) where 𝑈𝑏𝑎(𝑡) is the control value at time t, representing the area of the rectangle around the barcode code, measured in pixel values; and 𝑒𝑟𝑟𝑑(𝑡) is the error in time t between the current location of the dji tello drone and the barcode code location (figure 5). the pid controller-based image processing is based on three key components: • the proportional gain 𝐾𝑃 regulates the drone’s reaction in direct proportion to the discrepancy between the intended and the current locations. the 𝐾𝑃 term in barcode scanning applications helps the drone in achieving a stable and precise position for accurate scanning. • the integral term 𝐾𝐼 gain considers the cumulative inaccuracy over time and modifies the drone’s flight behaviour. this variable allows the drone to compensate for any systemic inaccuracies, such as drift, that may arise over extended flights. • the derivative gain 𝐾𝐷 is responsible for considering the rate of change of error and aids in stabilising the dji tello drone’s flight by reducing sudden movements or overshooting. this approach guarantees seamless and regulated motions when scanning barcodes. the incorporation of these three concepts in the pid controller enables the dji tello drone to uphold stability, precision, and agility throughout flights, rendering them an effective technique for barcode scanning applications in warehouse 4.0. 3. experimental setup this study utilised a quadcopter drone, namely, dji tello (figure 4(a)), equipped with a 5 mp camera capable of capturing photographs and 720 p video footage. the drone is equipped with a high-resolution camera, allowing it to capture and produce clear images that are well-suitable for the immediate processing of photographs and videos. given that this drone has a battery capacity of 1100 mah, it can travel a distance of 100 m and has a wonderful flying length of 13 min without any interruptions. in addition, this drone is capable of travelling a distance of 100 m. the drone has been programmed and controlled using python and its various libraries, ensuring a streamlined and efficient programming process. python is a programming language extensively utilised in scientific and computational domains. this tool has been developed to manage scale sequencing data, simplifying the process of crafting scripts, for data analysis [54]. pycharm is used to write a code, and it is a popular python integrated development environment (ide) that offers various features, such as auto-completion, code analysis, debugging capabilities and interoperability with version control systems [55]. this programming facilitated seamless integration for real-time processing of photos and videos. the versatility, ease of programming and wide range of capabilities of the dji tello drone makes it an ideal instrument for acquiring high-quality data in various scenarios. figure 4(b) denotes the coordinate axis of the drone in terms of its body, where roll ∅, θ pitch and yaw ψ represent the rotation of the drone around the x, y and z axes, respectively. roll is the rotation of the drone around the x-axis, pitch is the rotation of the drone around the y-axis, and yaw is the rotation of the drone around the z-axis. figure 5 shows the main three components that are implemented to verify the methodology of this study, namely: (1) a dji tello drone, (2) a potential barcode of the product, and (3) a laptop. table 1 shows the summary of the dimensions and specifications of these components. samer al-hamadani al-khwarizmi engineering journal, vol. 21, no.2, pp. 72-92 (2025) 77 (a) (b) fig. 4. (a) dji tello drone components; (b) the roll, pitch and yaw angles of the dji tello drone table 1, dimensions and specifications of the experiment setup components component parameter description dji tello weigh 80 g dimension 98×92.5×41 mm flight feature maximum flight distance: 100 m maximum speed: 8 m/s battery detachable: 1.1 ah/3.8 v life: approximately 13 min camera photo: 5 mp video: 720p fov: 82.6 cpu intel i7-7200u ram ddr4 12 gb connectivity wifi 2.4 ghz programming environment –python programming language –pycharm ide barcode 1 type printed on the carton dimension 14.75 × 2.9 cm barcode 2 type labeled on the carton dimension 9.6 × 7.1 cm barcode 3 type labeled on the carton dimension 5.3 × 4 cm laptop device name msi processor intel(r) core (tm) i5-10500 h cpu @ 2.50 ghz ram 8 gb system windows 10 samer al-hamadani al-khwarizmi engineering journal, vol. 21, no.2, pp. 72-92 (2025) 78 the pid controller and image processing algorithm are written in python code on the laptop. the written code is uploaded into the quadcopter to control the intended task through wifi. the quipped camera of the drone captures the scanned barcode information, which is transmitted via wifi to be processed by the python code. figure 6 shows the block diagram of the experimental system. fig. 5. main components of the experimental tools fig. 6. block diagram of the experimental system 4. pid controller design in this section, the pid gains are practically set to enable the dji tello drone to accurately detect barcodes. the required pid gain values are set to ensure that the dji tello drone movements are relatively steady during barcode tracking. nonetheless, these gains are susceptible to alteration. alternative values are used to evaluate the effect of pid gains on the drone’s motion and reaction during the barcode detection process through trial and error. the objective of the train and error was to minimise the error between the desired and the actual areas of the barcode in terms of pixel values. table 2 presents the values of the pid gains that are set in a trial-and-error method where the amount of overshot is noted during the experiment to reach the best result. test 2 was used as a case study for this value. some values resulted in a quick response to commands by the drone, causing fast and irregular movements. moreover, the delay in error processing resulted in a high level of oscillation and instability in the motion. consequently, the best values of k_p, k_i and k_d are set as 0.51 0.3, and 0.64, respectively. given these gain values, the system will exhibit a quick response to errors, ranging from moderate to fast, whilst also demonstrating effective error management capabilities. a higher k_i value indicates that the system will efficiently minimise accumulated errors and achieve a stable state. in addition, stable control is achieved when the k_d parameter of the system effectively minimises potential oscillations by counteracting the effect of sudden variations in error. the system can detect additional fixed points. however, these points will be of utmost importance in this study. samer al-hamadani al-khwarizmi engineering journal, vol. 21, no.2, pp. 72-92 (2025) 79 table 2, overshoot, steady-state error and accuracy value during the trial and error 5. experimental tests the dji tello drone camera captures the warehouse environment in a particular situation through video streaming. the presented technique in this study utilises opencv and the pyzbar library (section 3.1) for the recognition and decoding of barcodes. these libraries are utilised in the vision processing, which includes built in ai functions in conjunction with accurate machine learning and neural networks. these libraries offer a system for processing encryption and vision processing in terms of images. however, the opencv and the pyzbar library in python programming are utilised to facilitate the dji tello drone vision in executing the objective tasks of barcode code detection. the vision data obtained from the dji tello drone camera serves as input, controlling the position of the drone to the potential barcode in the warehouse. the height of the drone flight is set as a variable input rather than a constant in the programming code to account for and adjust various elevations. this mechanism enabled the potential to manipulate various elevations of barcodes. as a starting point, the drone is programmed to be located at the level of the product boxes of the experiment, which is 180 cm (figure 7). this notion indicates that the distance between the product on the shelf and the drone before takeoff is 180 cm. upon execution of the algorithm, the drone will automatically take off at a constant speed and proceed to the designated destination at speed (10 cm/s) to bein the process of scanning the product box. at the specified elevation of 180 cm, if the drone fails detect the barcode within 3 s, then it will travel ahead towards the product box at a distance equal to 30 cm. this distance is consistently minimised and computed from the drone’s last capture, guaranteeing continual progress towards the target box. if the drone is unable to scan at this distance, then it will return to the original distance of 30 cm before proceeding to scan another barcode to prevent any possible collisions. this process guarantees precise identification when the potential box of a product has no barcode. the developed pid controller-based image processing algorithm of this study is shown in figure 8. the algorithm closely depends on the pixel area of the drawn rectangle around the barcode for accurate navigation and positioning. when the barcode detection process is initiated, the drone scans it and moves onward until the pixel area meets the specific threshold. a tolerance of ±4000 pixels has been implemented for the specified barcode area to consider drone vibration and camera noise during a flight. this level of tolerance, ±4000 pixels, is determined through a process of trial and error and is granted or awarded. as the drone flies, it naturally moves, resulting in a constantly changing and non-fixed area. this tolerance is appropriate for any potential circumstance that could occur due to drone vibration and camera noise. when assessing the tolerance and measuring it, the distance between test k_p k_i k_d overshoot value in pixels steady state error in pixels accuracy 1 0.53 0.25 0.7 2500 150 0.375% 2 0.56 0.2 0.6 3750 130 0.325% 3 0.59 0.15 0.7 5150 170 0.425% 4 0.62 0.3 0.75 6250 160 0.4% 5 0.71 0.25 0.8 7400 200 0.5% 6 0.58 0.28 0.58 4325 140 0.35% 7 0.6 0.32 0.78 5240 170 0.425% 8 0.54 0.35 0.85 3150 190 0.475% 9 0.55 0.4 0.9 2100 185 0.4625% 10 0.53 0.28 0.74 1550 140 0.35% 11 0.55 0.3 0.75 1600 150 0.375% 12 0.53 0.3 1.1 3900 210 0.525% 13 1 0 1 7000 230 0.575% 14 0 1 1 5500 210 0.525% 15 best value 0.51 0.3 0.64 1250 100 0.25% samer al-hamadani al-khwarizmi engineering journal, vol. 21, no.2, pp. 72-92 (2025) 80 the barcode and the drone has been found to be 2 cm to 4 cm. this distance is considered appropriate because it ensures that the drone does not collide with the object or shelf. three tests are implemented for various barcode features to verify the results of the suggested technique of this study. moreover, three barcodes of different sizes are utilised to measure the pixel area of each barcode. the words large, medium and small are selected to represent the relative size between the three selected barcodes of this study. in terms of the pid controller gains (table 1), the optimal values of k_p, k_i and k_d have been set to 0.51, 0.3 and 0.64, respectively, across all three tests, effectively minimising the error. fig. 7. practical drone barcode scanning fig. 8. flow chart of the implemented algorithm 5.1 test 1 in test 1, the large-size barcode 1 measured 14.75 cm in width and 2.9 cm in length. this barcode type is affixed and printed on the product carton (figure 9). the pixel area is found to be rb = 15,000 pixels for reading and capturing a sharp image of the barcode, providing a suitable corresponding approximate reading distance of 55 cm (figure 10). product high cm a e off point samer al-hamadani al-khwarizmi engineering journal, vol. 21, no.2, pp. 72-92 (2025) 81 fig. 9. barcode data and area of the large-size barcode 1 of test 1 the process of detecting the barcode is implemented without considering the pid controller. in this case, the response of the process of detecting barcode 1 is shown in figure 11. the steady-state error is large, reaching an average of about 4800 pixels (figure 11(b)). accordingly, the detecting rate of the barcode area reached approximately 20,000 pixels (figure 11(a)), which is not close to the desired value of 15,000 pixels. thus, the intended barcode 1 could not be detected, even considering tolerance in the range of 4000 pixels. fig. 10. distance to barcode 1 detection (a) (b) fig. 11. barcode scanning without a pid controller: (a) barcode 1 image area; (b) barcode 1 image area error the designed controller of this study is considered in the process of detecting barcode 1. the implementation of the pid controller demonstrates its ability to minimise the image area error to ±200 pixels (figure 12(b)). this mechanism enhances the process of detecting the barcode, wherein the actual image area ‘ a_b’ reached the desired image area ‘r_b’, which is equal to 15,000 pixels (figure 12(a)). in this situation, the pid controller showed its ability to detect the barcode whilst maintaining a smooth drone motion. samer al-hamadani al-khwarizmi engineering journal, vol. 21, no.2, pp. 72-92 (2025) 82 (a) (b) fig. 12. barcode image area versus time with a pid controller: (a) barcode image area; (b) barcode image area error 5.2 test 2 in test 2, the medium barcode 2 dimension is set to 9.6 cm in width and 7.1 cm in length. unlike in test 1, this label is drawn by us. this label barcode is utilised on product packaging solely as a label (figure 13). the barcode area is 40,000 pixels, whilst the distance between the dji tello drone and the barcode label is 40 cm (figure 14). fig. 13. barcode data and area of the medium-size barcode 2 of test 2 fig. 14. distance to barcode 2 detection the task of detecting the barcode is performed without the implementation of the pid controller. in this situation, the response of the process of detecting barcode 2 is presented in figure 15. the steady state error was large, reaching an average of about 7000 pixels, due to the exclusion the pid controller in the barcode detection process (figure 15(b)). consequently, the detection rate of the barcode area reached approximately 47,000 pixels samer al-hamadani al-khwarizmi engineering journal, vol. 21, no.2, pp. 72-92 (2025) 83 (figure 15(a)), which is not close to the desired value of 40,000 pixels. this sitation resulted in the inability to detect the intended barcode 2, even when considering tolerance in the range of 4000 pixels. (a) (b) fig. 15. barcode 2 scanning without a pid controller: (a) barcode 2 image area; (b) barcode 2 image area error the developed controller of this study is considered in the task of detecting barcode 2. the implementation of the pid controller showed its ability to minimise the image area error to ±100 pixels (figure 16(b)). this mechanisn enhances the process of detecting the barcode, wherein the actual image area ‘a_b’ reached the desired image area ‘r_b’, which is equal to 40,000 pixels (figure 16(a)). in this situation, the pid controller showed its ability to detect the barcode whilst maintaining a smooth drone motion. (a) (b) fig. 16. barcode 2 image area versus time with a pid controller: (a) barcode 2 image area; (b) barcode 2 image area error 5.3 test 3 in test 3, the small barcode 3 is selected as the smallest amongst the three tests. this barcode is measured to be 5.3 cm in width and 4 cm in length. the barcode 3 label is also affixed to the product packaging (figure 17). the barcode area is 25,000 pixels, corresponding to a distance of 25 cm between the dji tello drone and the barcode label (figure 18). fig. 17. barcode data and area of the small-size barcode 3 of test 3 samer al-hamadani al-khwarizmi engineering journal, vol. 21, no.2, pp. 72-92 (2025) 84 fig. 18. distance to barcode 2 detection the task of detecting the barcode is applied without considering a pid controller. in this situation, the response of the process of detecting barcode 3 is presented in figure 19. the steady state error was large, reaching an average of more than 4250 pixels, due to the exclusion of the pid controller in the barcode detecting process (figure 19(b)). consequently, the detection rate of the barcode area reached approximately 29,250 pixels (figure 19(a)), which is not close to the desired value of 25,000 pixels. this situation resulted in the inability to detect the intended barcode 2 even considering tolerance in the range of 4000 pixels due to the oscillation in the drone when moved or stopped. (a) (b) fig. 19. barcode 3 scanning without a pid controller: (a) barcode 3 image area; (b) barcode 3 image area error the developed controller in this study is considered in the task of detecting barcode 3. the implementation of the pid controller showed its ability to minimise the image area error to ±600 pixels (figure 20(b)). this situation caused the enhancement of the process of detecting the barcode, wherein the actual image area ‘a_b’ reached the desired image area ‘r_b’, which is equal to 24,000 pixels (figure 20(a)). in this situation, the pid controller showed its ability to effectively detect the barcode whilst maintaining a smooth drone motion. samer al-hamadani al-khwarizmi engineering journal, vol. 21, no.2, pp. 72-92 (2025) 85 (a) (b) fig. 20. barcode 3 image area versus time with pid controller: (a) barcode 3 image area; (b) barcode 3 image area error 5.4 test 4 in monitoring the flight behaviour of the dji tello drone during scanning and detecting a potential barcode, test 4 is implemented to address the roll, pitch and yaw angles of the dji tello drone specified in figure 4 (b) and its altitude over time. the aforementioned drone flight behaviour is monitored using the designed pid controller and the proposed algorithm developed in this study for barcode detection. this test is conducted using the configuration parameters from test 2 as a case study for barcode 2 whilst also considering the influence of noise. however, in this test, the noise is assumed in the form of image data, where an unclear image is obtained due to the presence of dust in the warehouse environment. dust is considered a potential source of unclear image acquisition data. the roll value exhibits minor fluctuations caused by the lateral motion of the drone during the initial approach to the barcode and thereafter reaches a stable state at 0° (figure 21). the pitch value initially changes as the drone moves towards barcode 2 whilst reading the barcode area, to attain the intended area. the associated oscillations can be observed throughout this motion. however, the value reaches a stable state at 0° after the barcode 2 area is detected. the noticeable differences in yaw result from the drone veering clockwise and counterclockwise to precisely adjust its angle for an accurate barcode reading. figs. 21. relation between the initial values of roll, pitch and yaw samer al-hamadani al-khwarizmi engineering journal, vol. 21, no.2, pp. 72-92 (2025) 86 in terms of drone altitude, the targeted height is equal to 180 cm (figure 7), which represents the height of barcode 2. when the drone approaches the intended altitude, it initiates a deceleration process at time 13 s to reach the targeted height location at 16 s (figure 22). subsequently, the drone ascends again to reach the precise objective, slightly surpassing it before entering the stabilisation phase. thereafter, the drone exhibits oscillations between 16 s and 25 s around the predetermined altitude due to the minor vibrations of the drone during flight. nevertheless, this drone exhibits a good stabilising capability, consistently achieving an accuracy of 1–3 cm around the intended altitude. between 1 s and 10 s, the initial bias of 80 cm results from the drone starting its flight at a predetermined height of 80 cm, as specified in its programming. fig. 22. altitude over time for the dji tello drone afterward, the ability of the introduced pid controller and algorithm in this study to overcome noise existing in the image data is tested (figure 23). the results showed that the introduced technique in this study can effectively mitigate the influence of noise, allowing for accurate reading of barcodes, as the opencv and pyzbar libraries provide processing without affecting the area or barcode data. fig. 23. barcode data extraction with noise 6. discussion the experimental results obtained from tests 1, 2 and 3, as evidenced by the comparisons of figure 11 with figure 12, figure 15 with figure 16 and figure 19 with figure 20, validate the efficacy of the developed pid controller in minimizing errors throughout the barcode scanning process. the oscillation of the drone body caused by the rotation of the propellers made it impossible to minimise the average barcode area tracking error to zero. in addition, even when the propellers are not rotating, the captured images still exhibit variability due to the noise in the drone camera itself. the efficacy of the constructed pid controller, in conjunction with the developed algorithm, to scan various barcode sizes is demonstrated in tests 1, 2 and 3, which samer al-hamadani al-khwarizmi engineering journal, vol. 21, no.2, pp. 72-92 (2025) 87 detect large, medium and small barcode sizes, respectively. the gathered barcodes encompass large, medium and small sizes frequently utilised in storage warehouses as potential case studies. consequently, the introduced methodology demonstrated a significant ability to successfully recognise all the specified potential barcodes whilst utilising the pid algorithm, as demonstrated by the data in table 3. table 3, comparison between using a pid controller and without a pid controller test 4 evaluates the dji tello drone’s performance, demonstrating the efficacy of the proposed pid controller in tracking the barcode region, resulting in a relatively smooth flight behaviour. figure 21 illustrates the roll, pitch and yaw angles of flying behaviour, whereas figure 22 represents the altitude. table 4 presents the effect of integrating integrated pid controller with image processing in our study. table 4, comparison of the average error without a pid controller and error with a pid controller according to table 4, the pid value for the second test exhibited greater stability than that of the first test, despite being smaller, due to the enhanced clarity of the second barcode, which featured more distinctly defined edges for the drone camera’s reading. by contrast, the first test presented a diminished length-to-width ratio due to its relatively small length compared with its width. the second barcode is comparatively large, facilitating clearer readability by the drone camera. in test 3, the area was challenging to be detected because to the barcode’s small size. the minimal distance between the drone and the barcode (figure 18) results in an adequate reading of the area. nonetheless, a discernible variation can be observed from 600 in test 3 to 100 in test 2, resulting in a comparatively low error rate in test 2 relative to test 3. in the first three tests, the larger barcode was detected at a greater distance by the drone (table 5). this phenomenon is attributed to the cameras that can more clearly see larger objects than smaller ones from a greater distance. feature with pid without pid barcode reading accuracy high; reads various barcode sizes less accurate due to the lack of dynamic correction. problems with small barcode sizes reading response a little longer; due to time taken to adjust barcode area tracking faster response read error rate low; pid minimises error fluctuation higher, performance fluctuation is occurs dealing with changing environmental conditions better; as pid helps in adapting to changes significantly affected by changes performance stability more stable; due to dynamic control. unstable in some conditions ease of implementation more complex and requires precise settings. easier to implement but less efficient tests average error without a pid average error with a pid test 1 5000 pixels 200 pixels test 2 4000 pixels 100 pixels test 3 3800 pixels 600 pixels samer al-hamadani al-khwarizmi engineering journal, vol. 21, no.2, pp. 72-92 (2025) 88 table 5, results of the three barcode areas and distances between the dji tello drone and the barcode label the response time of barcode detection is shown in table 6, based on figures 11, 12, 15, 16, 19 and 20. the pid controller minimises the time of barcode detection. the response of detecting the barcode reduced with the decrease in the size area of the barcode. this phenomenon is reflected in the results presented in table 5, which show that the distance for barcode detection decreases with the decrease in the size of the barcode. table 6, time response for the barcode scanning area. drones can achieve exceptional barcode scanning performance by utilising sophisticated computer vision technology based on a pid controller, which includes image processing and machine learning algorithms embedded in the opencv and pyzbar libraries. an inherent advantage of using pid computer vision for barcode identification is its ability to adapt to changing circumstances, such as noise in the warehouse, which affects the acquired image data (figure 23 of test 4). 7. conclusions the advancements in barcode scanning, combined with the application of the pid computer vision methodology, can offer new opportunities for drones to detect barcodes in a highly precise manner, even in the presence of potential noise in warehouse environments. the methodology introduced in this study demonstrated the drone’s ability to avoid collisions with boxes or warehouse infrastructure, even in amidst noise, by ensuring that the drone maintains a consistent distance from the barcode. however, accuracy, response time and challenges are amongst the key points highlighted in this study. the accuracy of the designed integrated computer vision pid controller reached 0.25% through the trial-and-error technique. this result is acceptable and showed its effectiveness in detecting barcodes in various situations and environmental conditions, even in amidst noise and quadcopter vibrations. furthermore, the response time for barcode detection indicates that the pid controller minimises the detection duration. the efficacy of barcode detection decreases with the decrease in the size of the barcode area. this phenomenon is attributable to the reduction in the distance between the dji tello drone and detected barcode with the decrease in the barcode size. one of the challenges is the necessary inclusion of a tolerance of ±4000 pixels for the barcode area, aimed at accommodating oscillations that are caused by the movement of the drone whilst it is in flight to improve the algorithm’s consistency. this adjustment aimed to improve the algorithm’s reliability. another challenge is the use of a suitable barcode threshold area. the drone can maintain a suitable distance from the barcode whilst reducing the likelihood of collisions with nearby objects or warehouse equipment. these pixel areas have been selected as the optimal threshold, which is a significant achievement in terms of guaranteeing precise and efficient barcode tracking in warehouse settings. in future work, optimisation techniques can be applied to determine the optimal values for the pid controller gains. reference [1] fadhillah, a. h. i., safrudin, a. t., & darma, s. 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(2007). psychopy— psychophysics software in python. journal of neuroscience methods, 162(1-2), 8-13 ( 2025) 72-92، صفحة 2، العدد21مجلة الخوارزمي الهندسية المجلد سامر رزاق هالل 92 pid مسح الباركود باستخدام طائرة كوادكوبتر بدون طيار باستخدام كاميرا الرؤية وتقنيات التحكم الجيل الرابع للمستودع في مصانع 3حسام جربی ،2الكريم عزة عبدالرزاق عبد، *1سامر رزاق هالل ، بغداد، العراق جامعة بغداد ، كلية الهندسة الخوارزمي ، قسم هندسة التصنيع المؤتمت 2،1 العربية السعودية نجامعة الحائل ،كلية الهندسة ، قسم الهندسة الصناعية 3 samer.razaq2204@kecbu.uobaghdad.edu.i االلكتروني:*البريد الخالصة من خالل تحويل المستودعات التقليدية إلى مستودعات ذكية، ال سيما في 4.0تلعب الطائرات بدون طيار دوًرا حيويًا في الجوانب األساسية للصناعة أثناء مسح الباركود بواسطة الطائرات بدون طيار، خاصة عندما تواجه كاميرا الطائرة مجال مسح الباركود. تنشأ العديد من المشكالت المحتملة بشكل متكرر لمواجهة هذه بدون طيار صعوبة في الحصول على صور مميزة بسبب عوامل مثل المسافة، أو التقاط الصورة أثناء الطيران، أو أبعاد الباركود المختلفة. و مسؤولة pid( مع تقنيات معالجة الصور. وحدة التحكم pidالتحديات، يقترح هذا العمل نهًجا جديدًا يجمع بين وحدة التحكم المتناسبة والتكاملية والمشتقة ) رة بدون طيار عن المراقبة المستمرة لمدخالت الكاميرا، واكتشاف الفرق بين صورة الباركود المخططة والحقيقية، وإجراء تغييرات فورية على موضع الطائ المذكورة على طائرة المنهجية تطبيق تم الكاميرا. أداء الدراسة. وكشفت dji telloلتحسين لهذه المقترحة المنهجية أداء من عمليا للتحقق بدون طيار . pidدات التحكم النتائج العملية أن الطائرات بدون طيار يمكنها تحقيق أداء رائع في مسح الباركود من خالل دمج تقنيات رؤية الكمبيوتر المتطورة في وح الكمبيوتر رؤية خوارزميات معلومات pidإن واسترجاع طيار بدون الطائرة كاميرات من عليها الحصول تم التي المرئية البيانات تحليل على قادرة الباركود في ظل مجموعة متنوعة من المواقف. mailto:samer.razaq2204@kecbu.uobaghdad.edu.i :this is an open access article under the cc by license al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 20, no. 4, december (2024), pp. 58-69 in plane loading he effect of combined cycling tmodified study for on dynamic edge crack propagation in a thin plate 2fathi a. a. alshamma ,*1israa abed alrazak mosleh raqbaghdad, i, of baghdad college of engineering, university mechanical department, 1,2 israa.mosleh2003m@coeng.uobaghdad.edu.iq: s email’corresponding author* (received 11 september 2023; revised 26 december 2023; accepted 19 march 2024; published 1 december 2024) https://doi.org/10.22153/kej.2024.03.003 abstract the significant risks associated with the occurrence of mechanical cracks in engineering applications are investigated in this paper. in particular, the specific type of crack propagation that results from mixed mode loading (modes i and ii), which spreads throughout most structures, and the conditions under which it can occur are presented. following the linear elastic fracture mechanics theory, non-proportional loading on specimens of aluminium alloy was accomplished by applying constant tensile loads in conjunction with periodic shear loads. a theoretical equation for the dynamic crack growth rate was constructed using griffiths law for mixed mode i/ii of the dynamic crack growth. this equation considers the influence of dynamic crack propagation. experimentally, a locally designed laboratory apparatus was modified to suit the nature of the applied loads on samples with edge pre-cracks and two types of samples of aluminium alloys (aa), 6061 and 5052, at the uni-standard system with an edge crack length of 5 mm at mid were used. a comparison of the types of alloys used to verify the validity of the results was performed. the results showed acceptable agreement in determining crack propagation rate when predicting the results of the theoretical and experimental analyses. the results in the sample showed 5052 (0.0006, 0.000633) mm/sec for the experimental and theoretical results, respectively. in contrast, the crack propagation rate amounted to 6061 (0.000183, 0.000222) mm/sec for the experimental and theoretical results, respectively. hence, sample 5052 started faster and propagated cracks faster than alloy 6061. keywords: mixed mode; shear cycling load; crack propagation; combined loads and crack growth 1. introduction mechanical fracture is one of the problem types of failure that must be considered when analysing and constructing any structural or mechanical machine because crack growth is one of the most common causes of failure in material [1][2]. hence, investigating the types of mechanical failures that can happen and represent a risk to human lives and material losses is necessary to treat or prevent occurences. the majority of mechanical applications, including to bridges, aircraft, and shafts that conduct movement, are subjected to compound loads. these combined loads are subdivided into proportional and non-proportional loads. detecting the highest stress or calculating the magnitude of non-proportional loading in mechanical construction can be very challenging. moreover, pinpointing exactly where the collapse will occur is impossible. the timing of the first crack propagation and the pace at which the crack spreads are the two primary factors considered when determining how long a mechanical fracture will last. many factors are affected by cracks resulting from the mixed mode [3]____ that affect it directly. moreover, the ratio of the length of the crack should not exceed stage i; that is, it should remain within the first stage in the paris eq. (1). ((da dn)⁄ = c(δkequ) m ) …(1) where the k equivalent represents the value of the equivalent stress intensity factor for modes i and ii, which represents the difference between the maximum and minimum values of the equivalent mailto:israa.mosleh2003m@coeng.uobaghdad.edu.iq https://doi.org/10.22153/kej.2024.03.003 israa abed alrazak al-khwarizmi engineering journal, vol. 20, no.4, p.p. 58–69(2024) 59 stress intensity factor. a number of factors, which have a direct effect on the growth and velocity of spread include the rate of diffusion, age of the metal, nanostructure of the metal[4], [5] and temperature [6], [7] shoud also be considered to avoid propagation in the material. jahed and col suggested using the formulas model, which focuses on the strain energy of the various metals. the occurrence of failure on various metallic materials can be anticipated by applying uniaxial and proportional loading at low cycle fatigue and high cycle fatigue. the complete failure of the material is based on the sum of their strain energies when it is in the condition of elasticity and plasticity. this approach can be achieved by applying loading in both the longitudinal and transverse directions [8]. zain and alshamma designed a new laboratory apparatus capable of applying single or multiple cyclic loadings, which facilitated the analysis of samples of genuine tubes with realistic sizes and the study of crack growth rate experimentally and numerically using the forman equation [9]. salman studied the effects of laser strikes on the formation of cracks in metals using a wide range of aluminium alloys (7049, 7050, 2024, and 6061) with thicknesses of 1 mm and 2 mm. the study used a laser cutting machine to create a central crack, and a neodymium-doped yttrium aluminum garnet laser to harden the area around the crack [10]. wang et al. investigated the dynamic crack growth on glass samples filled with epoxy with varied lengths of cracks, and the spreading rate and effect of these lengths on enhancing the spreading rate in the mixed mode of loading [11]. two types of methods are generally used in treating the occurrence of cracks in the mechanical structure. the first type of method is treatment methods. such as welding, heat treatment, etc., which may not be effective in preventing the growth of the crack or may be expensive. the second type of method lies in predicting the rate of propagation speed in the material, which is possible by studying the rates of the possibility of failure occurring in the material. this is the subject of study in this research, which deals with two different types of aluminium alloys [12] selected for the purpose of conducting fracture and crack growth tests. these aluminium alloys can be specified under uni standard 5052 and 6061 [13] based on hardening vickers tests [14] and chemical composition analysis [15]. the tests were conducted to determine the type of specification within the temperature range of 27 °c and humidity of 20%. the main objectives of this research are as follows:  study the crack growth rate and predict the instability stage entering to avoid failure in the material.  design an apparatus that applies combined fatigue loads to specimens by applying a constant tensile load and cyclic shear loads.  identify the crack initiation and propagation rates for two types of aluminium alloys and comparing their results and behaviours.  derive an equation for finding the crack growth rate using the griffith energy balancing method and verify the experimental result. 2. methods 2.1 theoretical analysis when studying a thin plate that is subjected to two different kinds of loads, such as in-plane, constant tensile load ,and on the other axis of cycling shear loading, in the theoretical calculations, the material is assumed to be linearly elastic calculation, follows hooke’s law, is isotropic and homogeneous. it is very important to derive an analytical model that can predict the occurrence of cracks and their propagation over a number of cycles. the crack growth rate for the mixed mode i/ii was extracted using equations, and an equation was derived using the griffith energies balancing equation for dynamic crack growth. the principle behind this equation is that the ratio of the perpendicular displacement to the direction of stress for both axes at the mixed mode i/ii loading inplane is extracted and the energy result used to drive the crack growth equation. 2.1.1 analytical model of displacement the westergaard stress function is used to analyse crack propagation in mixed mode [16]. 𝛟z(i+ii) = 𝜎 .𝑍 √𝑍2−𝑎2 …(2) the following relationships can be derived from equation (1): z = r. e i𝛉 …(3) z-a = r1 .e i𝛉1 ...(4) israa abed alrazak al-khwarizmi engineering journal, vol. 20, no.4, p.p. 58–69(2024) 60 fig. 1. standing theory of cracks. the westergaard equation based on [17] is used to solve the complex number using the airy stress function. z + a = r2. e i𝛉2 …(5) where z is a complex function with the variable position located on the plate found relative to the points on cracks a, b and c [17]. for plain strain: v = 2σeff e (1 − υ2). √a2 − x2. for plain stress: v = 2σeff e′ . √a2 − x2 …(6) where 1 e′ = (1−υ2) e , assume 𝑥 = 𝑐𝑎 0 < 𝑥 < 1 , let 𝑐1 = 2√1 − 𝑐2, based on that, the displacement of the crack (v) for the mixed mode i/ii is v = c1 e . σeff. a …(7) the effective stress 𝛔eff for mixed mode i/ii comes from the tensile load in direction and cycling shear load within the elastic limit in mpa [18], as shown in fig. 2. σeff = 1 √2 √[ σ2 + (τo. sin (w.t 2 ))2] …(8) the rate of displacement (v̇) is determined by subtracting equation (8) from equation (7) and then constructing the equation for the stress and crack length variables using this information. v̇ = c1 e` . [ ao √2 . w. τo 2 . sin(w. t) 4 [ σ2 + (τo. sin (w. t 2 )) 2 ] 1 2⁄ + 1 √2 . [ σ2 + (τo. sin (w.t 2 )) 2 ] 1 2⁄ . da dt ] … (9) to determine the entire amount of kinetic energy [19], denoted as (t total), fig. 2. loads on the sample, which shows the method of exposing fatigue loads on the plate in the device (constant tensile stress towards the y-axis and periodic shear loads by pressing the sample parallel to the x-axis within the elastic limit ) to obtain the type of non-proportional loads with mixed mode. = 1 2 . ρ. area. v•2 … (10) after making substitutions in eqs. (8–10) and deriving the displacement of the crack (v) and the stresses, the total kinetic energy (ttotal) equation was obtained as follows: 𝐓𝐭𝐨𝐭𝐚𝐥 = 𝛒 𝐤𝐚𝐢 𝟐 𝟐𝐄`𝟐 [(𝛔𝟐 + 𝛕𝟐𝐬𝐢𝐧𝟐 (𝐰.𝐭 𝟐 )) . (𝐝𝐚 𝐝𝐭 ) 𝟐 + 𝝉𝟐. 𝐚𝐨 𝐰 𝟐 . 𝐬𝐢𝐧 (𝐰.𝐭 𝟐 ) . (𝐝𝐚 𝐝𝐭 ) + 𝝉𝒐 𝟐. 𝒂𝒐 𝟐 𝒘𝟐 𝟒 . 𝒄𝒐𝒔𝟐 (𝒘.𝒕 𝟐 )] ...(11) 2.1.2. excess energy rate to determine the excess energy rate (u) controlled by the crack’s extension at the mixed modes (i/ii) in the thin plate [17], [18] for fig. 3, the following equation is used: u = ∫ (g − r). da = − ∫ r. da + ∫ g. da ai ao ai ao ai ao … (12) the total excess energy (u) for the mixed modes i/ii [5], [20] is determined as follows: u = ( σ2 2e + 2(1+υ) e (τ𝑜. sin wt 2 ) 2 ) …(13) z • • • a b c x x y edge -pre crack 5mm israa abed alrazak al-khwarizmi engineering journal, vol. 20, no.4, p.p. 58–69(2024) 61 fig. 3. energy balance of the crack, which demonstrates the effect of the balance of energies and the influence that the amount of excess energy exerted on the plate in terms of the increase in the crack length from (ao) to (ai) [17]. physically, it has been scientifically proven [21], [22] that the deformation that appears at the crack edge, which forms the plastic area around and at the tip of the crack, enhances the resistance to the appearance of cracks. as a result, the necessary energy that the crack needs to start growing is higher in the crack at the middle because of the two tips of the crack in the centre crack in the plate. therefore, this research adopts the assumption adopted that the energy surrounded by the crack is defined as an area that resembles a circle. the excess energy required to start the growth of the crack is less in the case of the crack at the edge (that is, it requires less energy to appear to grow). the excess energy is expressed in the speed of the risk of spread rate and the size of the circle surrounding the crack is not similar in the previously studied cases. the area is smaller, and the diameter of the circle becomes (a), as shown in fig. 4, and the radius of the circle is (a/2), where the prediction of the theoretical results will be compared later with the propagation rate of the crack and its failure to reach the stage of failure, the experimental results. the amount of excess energy, uo, per unit thickness for an edge crack is as follows: uo = ( σ2 2e + 2(1 + υ) e (τo. sin wt 2 ) 2 ) . πa2 4 )14(… fig. 4. energy around the crack at the edge of the sample. the value of the excess energy is transformed into the total energy as the cracking begins to propagate. this conversion results in kinetic energy and heat; however, the heat energy is negligible in a thin plate and can be ignored (u = ttotal). ( σ2 2e + 2(1 + υ) e (τ𝑜 . sin wt 2 ) 2 ) πa2 4 = ρ kai 2 2e2 [(σ2 + τ𝑜 2sin2 ( wt 2 )) . ( da dt ) 2 +τ𝑜 2. ao. w 2 . sin ( wt 2 ) . ( da dt ) +τ𝑜 2. ao 2 w2 4 . cos2 ( wt 2 )] )15(… where equation (15) is the final crack growth equation. 3. experimental work before the samples undergo the apparatus, the mechanical properties, which are represented by conducting the vickers hardness test and the tensile test, and the chemical properties, must be determined. the x-ray device was used to analyse the samples to study and understand their properties, components of chemical elements, and engineering behaviour as shown in fig. 5. excess energy owning to unstable crack growth g, r oa ia icr=g total crack length, a a dge e crack x israa abed alrazak al-khwarizmi engineering journal, vol. 20, no.4, p.p. 58–69(2024) 62 fig. 5. mechanical tests: a) vickers hardening test; b) zwick tensile test machine; c) standard specimens for tensile test. tables 1 and 2 show the chemical composition and mechanical properties of the samples. table 1, chemical composition for samples table 2, mechanical properties for samples the research apparatus that applies a combined load on the sample was designed regionally [5]. the tensile load is applied in the vertical direction relative to the level of the crack surface to generate the opening mode (mode i), and the apparatus is placed on the other axis of the specimen to be the cycling load to develop into mode ii, which consists of periodic shear loading. the apparatus generates both modes. a hydraulic system includes a hydraulic pump, hydraulic transmission tube, pressure gauge to indicate the amount of tension applied to the sample and manual lever to operate the hydraulic pump that produces the tension force. in terms of cycling shear stress, the movement is produced by an electric motor with a rotational speed of 1000 revolutions per minute in direct current type with three phases. it transmits a shaft through a v-type transmission belt and a lever connected to the shaft is used to convert it into a linear motion. this is the location where the rotational motion is transformed into a linear motion. figs. 7 and 8 show the lever possesses a screw for the purpose of controlling the amount of displacement that enters the sample holder. fig. 6: a) strain meter device; b) strain gauge paste on the specimen. this step allows the value of the shear strain that was applied on the specimen to be measured by two strain gauges with 120 ohms attached at the centre of the sample and to the top and bottom faces (halfbridge) [24], see fig. 6 (a and b). six sample clamps make up the total number available; two are permanently attached, and the fourth clamp is fixed. a ) b ) c ) elements 6061 aa 5052aa si 0.34 0.491 fe 0.514 0.491 cu 0.043 0.249 mn 0.118 0.0988 mg 2.59 0.933 cr 0.0168 0.108 ni 0.0063 0.0076 zn 0.0376 0.0242 ti 0.008 0.0093 pb 0.0156 0.012 al 96.3 97.6 properties 6061 aa 5052 aa ultimate stress (mpa) 288.95 215.34 yield stress (mpa) 249.65 106.23 elongation % 13.8 106.23 hardening vickers test 98 60 modules of elasticity (gpa) 68.9 70.3 israa abed alrazak al-khwarizmi engineering journal, vol. 20, no.4, p.p. 58–69(2024) 63 rogrampby solid work evice dthe fig. 7. section of one of the movable sample grippers is connected to the hydraulic pump that pulls it out with a tensile strength of 30 bar. the other gripper is connected to the arm generating periodic shear load on the sample with an entry value of 0.00188 of shear strain to ensure that the stresses investigated under the high fatigue cycle theory are within the elastic limit. fixed tensile stress was applied to the y-axis while cyclic shear stress with its lowest value equal to zero and its highest value equal to (𝛕 = 49.088 mpa) was applied to the x-axis. fatigue deviceof the fig. 8. section the specimen has an edge pre-crack length of 5 mm and a thickness of 0.2 mm; the overall dimensions of the specimen are 160 x 40 x 2mm. the specimen was cut and cracked using a wirecutting (electrical discharge machining), as shown in ( fig. 9). rack cb) specimen um alloyiluminafig. 9: a) propagation the growth of the crack in the sample was observed using a digital camera (nikon coolpix b700), and the data were transformed to determine the length of the crack using the image processing software (image j). 4. results and discussion the results of the experiments indicate differences in the rate of crack initiation and growth between the 6061 and 5052 aluminium alloys. the differences were based on the elasticity of the material, which is the initiation of life, and the crack )a israa abed alrazak al-khwarizmi engineering journal, vol. 20, no.4, p.p. 58–69(2024) 64 growth rate will decrease as this rate increases. in contrast, if initiation does not occur, the growth rate will rise, and the material will be characterised as brittle. the results of the rate of crack length during the time and number of cycles n were compared with the data generated from the theoretical analysis equation derived in study )equation (15)). .n) for alloy 5052-(a of esultrfig. 10. a comparison of the number of cycles (n) with the length of the crack (a) formed for the experimental and theoretical results from (equation 15) for sample 5052, in which the pre-prepared crack begins to grow at 100,000 cycles shows that initially, the results are close, reaching a length of 7 mm 195,000 cycles. at a length of 14 mm, the crack begins to increase in growth velocity, indicating that it has reached the instability stage. fig. 10 shows that the general crack growth rates were 0.0006 and 0.000633) mm/s for the experimental and theoretical results from (equation 15). .n) for alloy 6061-esults in (arfig. 11. for sample 6061, the number of cycles (n) and the length of the crack (a) formed for the experimental and theoretical results from equation 15 where the crack of initiation was at 250000 cycles. the results are close, and the length of 10 mm was reached when the number of cycles of 1075,000 cycles. figure 11 shows that at the length of 18 mm, the crack begins to increase in the growth velocity, indicating that it has entered the instability stage. the general crack growth rates were (0.000183 and 0.000222 mm/s for the experimental and theoretical results from (equation 15). n) for alloys 6061 -(a ofs xperimental resultefig. 12. .and 5052 the m and c values of the paris equation [25] were extracted experimentally and analytically using the log plot method, where the value of c is (8.5113*10-7, 6.309*10-7) (mm cycle⁄ ) (𝑀𝑃𝑎√𝑚)⁄ and m is (2.3571, 2.428) for alloy 6061, while the value of c is (2.958*10-6, 4.6773*10-6) (mm cycle⁄ ) (𝑀𝑃𝑎√𝑚)⁄ and m is (2.056, 1.6609) for alloy 5052. results for the xperimental and theoreticalefig. 13. alloy israa abed alrazak al-khwarizmi engineering journal, vol. 20, no.4, p.p. 58–69(2024) 65 the crack initiation for the two samples at 100,000 and 250,000 cycles for the two samples, 5052 and 6061 were based on the experimental results as shown in figs. (10–13). in contrast to the crack that occurred in sample 6061, which could be difficult to observe with the naked eye because of the molecular characteristics of the material, the shape of the crack in sample 5052–aa was often plainly apparent and contains simple granular zigzags. fig. 14. crack propagation in alloys experimentally: a. alloy 5052-aa; b. alloy 6061-aa in contrast, the crack that formed in sample 6061 was difficult to notice with the naked eye, as shown in fig. 14. initially, an agreement in the prediction of the findings could be observed and used to examine the relation between the length of the crack and the number of cycles. when the results are compared with the analysis using the mathematical model delivered to fit into the mixed mode i/ii non-proportional loading applied on the sample, figs. 15 and 16 show the stages of crack growth in the samples .aa-fig. 15. crack growth steps in 5052 .aa-fig. 16. crack growth steps in 6061 when the number of cycles is increased, a difference can be observed between the experimental and theoretical curves. the reason for this difference is due to the nature of the material [26] in the experimental test; the material used was a commercial material intended to examine normal behaviour when cracking occurs in the structures and mechanical parts. it is not a standard alloy (because of the presence of impurities and the granular structure of the material). moreover, despite the vibration being basic [23], it can influence the spread because it is created by the device when it rotates at a high speed and the test temperature. 5. conclusion  the experimental results are consistent with the mathematical model developed for the research. the estimate of a crack growing in the material at the beginning of the chart indicates the connection between the length of the fracture and the number of cycles.  it was shown from the procedures of studying experimental fatigue test methods for cyclic loads on materials that the initiation of crack for sample 6061 was larger than that for sample 5052 by a percentage equal to 60%.  the experimental work shows the rate of crack growth in sample 6061 aa was lower than the rate of crack growth in sample 5052 aa. this finding implies that sample 6061 requires more time than sample 5052 to reach the failure stage, 19560 sec sec 19200 sec 17400 sec 16500 sec 13320 sec 11220 15000 sec sec sec 46200 64800 sec 82200 sec 102000 sec israa abed alrazak al-khwarizmi engineering journal, vol. 20, no.4, p.p. 58–69(2024) 66 also known as mechanical fracture, with a percentage of 75.03%.  based on the composition of the chemical properties of the samples and the rate of crack growth, it can be inferred that the samples within aluminium alloy 6061 are ductile material alloys with relatively small grain size. this characteristic explains why the rate of crack growth in that type of alloy is slow; the small grains increase the possibility of crack occurrence, which, in turn, causes the rate of crack growth to become slower. a relatively plastic strain between the grains, in addition to the production of big plastic deformation in the area surrounding the fracture in an attempt to prevent the crack from happening and for the same reason, may explain why this would be the case.  in contrast to sample 5052, which is defined by big grains, the speed of spread of the crack and the great distance to the crack that grew, this sample is distinguished by the type and shape of the crack that formed within it, which is specified as a brittle material.  some influencing variables, in addition to the basic nature of the alloy’s elemental makeup, are responsible for the difference that may be observed between the experimental and theoretical results at the end of the crack formation process.  a comparison of the analytical findings for alloy 5052 with the experimental result indicated the analytical model with the error rate in crack growth rate is 5.23%. the percentage of error for alloy 6061 is 17.5%, which is a good estimate for estimating the time of failure.  the c and m values found for the paris relation crack propagation through the application of the logarithmic diagram are at acceptable levels within the ranges that aluminium alloys have defined for themselves. nomenclature and units da/dn fatigue crack growth rate, mm / cycle keq stress intensity factor equivalent, mega pascal. m constant factor of paris equation, unitless. c constant factor of paris equation, (mm/cycle) / (mpa√𝑚 ). a length of crack, meter. ai last length in the crack, meter. ao original length of the crack’s length, meter. z complex number that gives the possibility of calculating any place on the slide in the stress function 𝛉, 𝛉1, 𝛉2 different angles relative to the location expressed by (z) r, r1, r2 radius from the different corners 𝛉, 𝛉1, 𝛉2, to the (z) position 𝛟z(i+ii) stress function for mixed mode (i/ii) e’ modulus of elastic, mega pascal. v displacement for the mixed mode. v• rate of displacement for the mixed mode. 𝛕o max value of shear stress, mega pascal. 𝛕 shear cycling load (mode ii), mega pascal. w angular velocity, rad /sec. t time, seconds. mass mass of the material, kilogram. t total total amount of kinetic energy, joule. g release energy rate of increase in fracture length, joule. r amount of energy being resisted by the fracture, joule. ki stress intensity factor for mode i, mpa√m. kii stress intensity factor for mode ii, mpa√m. 𝛔eff the effective stress for the mixed mode, mega pascal. u total amount of excess energy, joule. uo the amount of excess energy per unit of thickness for edge crack, joule. da /dt rate of crack growth, m/sec. 𝛔 tension stress, mega pascal. ɵc angel of crack, degree 𝛖 poisson’s ratio, unit less ρ density of the material, kg/m3 declaration of interest the authors declare that they have no conflicts of interest financial or personal relationships with other persons or organisations that could improperly influence their work in connection with the publication of this article. submission declaration the authors declare that the work described has not been previously published, that it is not under consideration for publication elsewhere, and that all authors have approved its publication in connection with the publication of this article. israa abed alrazak al-khwarizmi engineering journal, vol. 20, no.4, p.p. 58–69(2024) 67 acknowledgement we thank everyone who have helped publish this study. we also thank the mechanical department at baghdad university for providing us with the resources and assistance to finish this project. finally, we appreciate all research participants’ time and willingness to share their experiences. their contributions have been crucial to our understanding and conclusions. funding sources this research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. references [1] p. zhang, j. li, y. zhao, and j. li, “crack propagation analysis and fatigue life assessment of high-strength bolts based on fracture mechanics.,” sci. rep., vol. 13, no. 1, p. 14567, sep. 2023, doi: 10.1038/s41598-02341804-z. 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(2024) 58–69، صفحة 4، العدد20مجلة الخوارزمي الهندسية المجلد اسراء عبد الرزاق مصلح 69 بتسليط حمل الشد الثابت مع القص الدوري على انتشار االحمال المركبةدراسة معدلة لتأثير تشققات الحواف الديناميكية في صفيحة رقيقة من األلومنيوم 2فتحي عبد الصاحب الشماع *1اسراء عبد الرزاق مصلح الميكانيك، كلية الهندسة، جامعة بغداد، العراق هندسة قسم 2، 1 m@coeng.uobaghdad.edu.iq2003israa.mosleh البريد االلكتروني :* المستخلص وع معين مننظرا لألهمية والمخاطر المحتملة المرتبطة بحدوث الشقوق الميكانيكية في التطبيقات الهندسية الهامة، فقد أصبح من الضروري البحث عن ن م عرض تلك انتشار الشقوق. هذه هي حالة شقوق الوضع المختلط التي تنتج عن الوضع األول والوضع الثاني للتحميل والتي تنتشر في معظم الهياكل، ويت تحقيق توليد إمكانية (، تمlefmالشقوق، باإلضافة إلى الظروف التي يمكن أن تحدث فيها، في هذه الحالة. في سياق نظرية ميكانيكا الكسر المرنة الخطية ) قانون جريفيث للوضع التحميل غير المتناسب على عينات من سبائك األلومنيوم من خالل تطبيق أحمال الشد الثابتة بالتزامن مع أحمال القص الدورية. باستخدام في االعتبار تأثير انتشار الكراك الديناميكي. تجريبياً تم تصميم لطاقة الشق، تم بناء معادلة نظرية لمعدل نمو الشق الديناميكي. تأخذ هذه المعادلة i/iiالمختلط (aaأللومنيوم )أجهزة مختبرية محلية الصنع وتعديلها لتتناسب مع طبيعة األحمال المطبقة على عينات ذات شقوق حافة مسبقة من نوعين مختلفين من سبائك ا مقارنة بين أنواع السبائك المستخدمة للتحقق من صحة النتائج. والتناقض بين مدى قرب بطول شق الحافة تم إجراء standard-uni، بنظام 5052و 6061 بشكل أسرع وتنتشر 5052 النتائج النظرية من النتائج الحقيقية للكسر الذي حدث. وأظهرت النتائج التوافق بين المعادلة النظرية والنتائج العملية. تبدأ العينة .6061الشقوق بشكل أسرع من السبائك mailto:israa.mosleh2003m@coeng.uobaghdad.edu.iq modified study for the effect of combined cycling loading in plane on dynamic edge crack propagation in a thin plate israa abed alrazak mosleh1*, fathi a. a. alshamma2 1,2 mechanical department, college of engineering, university of baghdad, baghdad, iraq *corresponding author’s email: israa.mosleh2003m@coeng.uobaghdad.edu.iq https://doi.org/10.22153/kej.2024.03.003 abstract the significant risks associated with the occurrence of mechanical cracks in engineering applications are investigated in this paper. in particular, the specific type of crack propagation that results from mixed mode loading (modes i and ii), which sp... keywords: mixed mode; shear cycling load; crack propagation; combined loads and crack growth 1. introduction mechanical fracture is one of the problem types of failure that must be considered when analysing and constructing any structural or mechanical machine because crack growth is one of the most common causes of failure in material [1][2]. hence, investi... ,(,da-dn).= c,,,δk-equ..-m.. …(1) where the k equivalent represents the value of the equivalent stress intensity factor for modes i and ii, which represents the difference between the maximum and minimum values of the equivalent stress intensity factor. a number of factors, which have... two types of methods are generally used in treating the occurrence of cracks in the mechanical structure. the first type of method is treatment methods. such as welding, heat treatment, etc., which may not be effective in preventing the growth of the ... the main objectives of this research are as follows:  study the crack growth rate and predict the instability stage entering to avoid failure in the material.  design an apparatus that applies combined fatigue loads to specimens by applying a constant tensile load and cyclic shear loads.  identify the crack initiation and propagation rates for two types of aluminium alloys and comparing their results and behaviours.  derive an equation for finding the crack growth rate using the griffith energy balancing method and verify the experimental result. 2. methods 1. 2. 2.1 theoretical analysis when studying a thin plate that is subjected to two different kinds of loads, such as in-plane, constant tensile load ,and on the other axis of cycling shear loading, in the theoretical calculations, the material is assumed to be linearly elastic calc... 2.1.1 analytical model of displacement the westergaard stress function is used to analyse crack propagation in mixed mode [16]. 𝛟z(i+ii) = ,𝜎 . 𝑍-,,𝑍-2.−,𝑎-2. .. …(2) the following relationships can be derived from equation (1): z = r. e i𝛉 …(3) z-a = r1 .e i𝛉1 ...(4) fig. 1. standing theory of cracks. the westergaard equation based on [17] is used to solve the complex number using the airy stress function. z + a = r2. e i𝛉2 …(5) where z is a complex function with the variable position located on the plate found relative to the points on cracks a, b and c [17]. for plain strain: v = ,2,σ-eff.-e.,1−,υ-2...,,a-2.−,x-2... for plain stress: v = ,2,σ-eff.-e′..,,a-2.−,x-2.. …(6) where ,1-e′.=,,1−,υ-2..-e. , assume 𝑥=𝑐𝑎 0<𝑥<1 , let ,𝑐-1.=2,1−,𝑐-2.., based on that, the displacement of the crack (v) for the mixed mode i/ii is v=,,c-1.-e..,σ-eff..a …(7) the effective stress 𝛔eff for mixed mode i/ii comes from the tensile load in direction and cycling shear load within the elastic limit in mpa [18], as shown in fig. 2. ,σ-eff.=,1-,2..,[ ,σ-2.+,(,τ-o..,sin-,,w.t-2...)-2.] . …(8) the rate of displacement (,v.) is determined by subtracting equation (8) from equation (7) and then constructing the equation for the stress and crack length variables using this information. ,v.=,,c-1.-,e-`...[,,a-o.-,2...,w.,τ-o-2..,sin-,w.t..-,4, ,σ-2.+,,,τ-o..,sin-,,w.t-2....-2..-,1-2... + ,1-,2..,., ,σ-2.+,,,τ-o..,sin-,,w.t-2....-2..,1-2...,da-dt. ] … (9) to determine the entire amount of kinetic energy [19], denoted as (t total), fig. 2. loads on the sample, which shows the method of exposing fatigue loads on the plate in the device (constant tensile stress towards the y-axis and periodic shear loads by pressing the sample parallel to the x-axis within the elastic limit ) to o... = ,1-2..ρ.area.,v-•2. … (10) after making substitutions in eqs. (8–10) and deriving the displacement of the crack (v) and the stresses, the total kinetic energy (ttotal) equation was obtained as follows: ,𝐓-𝐭𝐨𝐭𝐚𝐥.=,𝛒 ,𝐤𝐚-𝐢-𝟐.-𝟐,𝐄-`𝟐..[,,𝛔-𝟐.+,𝛕-𝟐.,𝐬𝐢𝐧-𝟐.,,𝐰.𝐭-𝟐....,,,𝐝𝐚-𝐝𝐭..-𝟐.+,𝝉-𝟐.. ,𝐚-𝐨.,𝐰-𝟐..,𝐬𝐢𝐧-,,𝐰.𝐭-𝟐....,,𝐝𝐚-𝐝𝐭..+,,𝝉-𝒐.-𝟐..,𝒂-𝒐-𝟐.,,𝒘-𝟐.-𝟒..,𝒄𝒐𝒔-𝟐.,,𝒘.𝒕-𝟐..] ... 2.1.2. excess energy rate to determine the excess energy rate (u) controlled by the crack’s extension at the mixed modes (i/ii) in the thin plate [17], [18] for fig. 3, the following equation is used: u=,,a-o.-,a-i.-,g−r..da=−,,a-o.-,a-i.-r.da+,,a-o.-,a-i.-g.da... … (12) the total excess energy (u) for the mixed modes i/ii [5], [20] is determined as follows: u=( ,,σ-2.-2e.+,,2,1+υ.-e.,,τ-𝑜..sin,wt-2..-2.) …(13) fig. 3. energy balance of the crack, which demonstrates the effect of the balance of energies and the influence that the amount of excess energy exerted on the plate in terms of the increase in the crack length from (ao) to (ai) [17]. physically, it has been scientifically proven [21], [22] that the deformation that appears at the crack edge, which forms the plastic area around and at the tip of the crack, enhances the resistance to the appearance of cracks. as a result, the necess... therefore, this research adopts the assumption adopted that the energy surrounded by the crack is defined as an area that resembles a circle. the excess energy required to start the growth of the crack is less in the case of the crack at the edge (tha... the amount of excess energy, uo, per unit thickness for an edge crack is as follows: ,u-o.=,,,σ-2.-2e.+,,2,1+υ.-e.,,τ-o..sin,wt-2..-2...,π,a-2.-4. …(14) fig. 4. energy around the crack at the edge of the sample. the value of the excess energy is transformed into the total energy as the cracking begins to propagate. this conversion results in kinetic energy and heat; however, the heat energy is negligible in a thin plate and can be ignored (u = ttotal). ,,,σ-2.-2e.+,,2,1+υ.-e.,,τ-𝑜..sin,wt-2..-2..,π,a-2.-4.= ,ρ ,ka-i-2.-,2e-2..[,,σ-2.+,,τ-𝑜.-2.,sin-2.,,wt-2....,,,da-dt..-2. +,,τ-𝑜.-2.. ,a-o..,w-2..,sin-,,wt-2....,,da-dt.. +,,τ-𝑜.-2..,a-o-2.,,w-2.-4..,cos-2.,,wt-2..] …(15) where equation (15) is the final crack growth equation. 3. experimental work before the samples undergo the apparatus, the mechanical properties, which are represented by conducting the vickers hardness test and the tensile test, and the chemical properties, must be determined. the x-ray device was used to analyse the samples to study and understand their properties, components of chemical elements, and engineering behaviour as shown in fig. 5. a edge crack x fig. 5. mechanical tests: a) vickers hardening test; b) zwick tensile test machine; c) standard specimens for tensile test. tables 1 and 2 show the chemical composition and mechanical properties of the samples. table 1, chemical composition for samples table 2, mechanical properties for samples the research apparatus that applies a combined load on the sample was designed regionally [5]. the tensile load is applied in the vertical direction relative to the level of the crack surface to generate the opening mode (mode i), and the apparatus is... fig. 6: a) strain meter device; b) strain gauge paste on the specimen. this step allows the value of the shear strain that was applied on the specimen to be measured by two strain gauges with 120 ohms attached at the centre of the sample and to the top and bottom faces (half-bridge) [24], see fig. 6 (a and b). six sample clamps make up the total number available; two are permanently attached, and the fourth clamp is fixed. fig. 7. section of the device by solid work program one of the movable sample grippers is connected to the hydraulic pump that pulls it out with a tensile strength of 30 bar. the other gripper is connected to the arm generating periodic shear load on the sample with an entry value of 0.00188 of shear s... fig. 8. section of the fatigue device the specimen has an edge pre-crack length of 5 mm and a thickness of 0.2 mm; the overall dimensions of the specimen are 160 x 40 x 2mm. the specimen was cut and cracked using a wire-cutting (electrical discharge machining), as shown in ( fig. 9). fig. 9: a) aluminium alloy specimen b) crack propagation the growth of the crack in the sample was observed using a digital camera (nikon coolpix b700), and the data were transformed to determine the length of the crack using the image processing software (image j). 4. results and discussion the results of the experiments indicate differences in the rate of crack initiation and growth between the 6061 and 5052 aluminium alloys. the differences were based on the elasticity of the material, which is the initiation of life, and the crack gro... a) the results of the rate of crack length during the time and number of cycles n were compared with the data generated from the theoretical analysis equation derived in study )equation (15)). fig. 10. result of (a-n) for alloy 5052. a comparison of the number of cycles (n) with the length of the crack (a) formed for the experimental and theoretical results from (equation 15) for sample 5052, in which the pre-prepared crack begins to grow at 100,000 cycles shows that initially, th... fig. 11. results in (a-n) for alloy 6061. for sample 6061, the number of cycles (n) and the length of the crack (a) formed for the experimental and theoretical results from equation 15 where the crack of initiation was at 250000 cycles. the results are close, and the length of 10 mm was reach... fig. 12. experimental results of (a-n) for alloys 6061 and 5052. the m and c values of the paris equation [25] were extracted experimentally and analytically using the log plot method, where the value of c is (8.5113*10-7, 6.309*10-7) ,,,mm-cycle..-,𝑀𝑃𝑎,𝑚... and m is (2.3571, 2.428) for alloy 6061, while the va... fig. 13. experimental and theoretical results for the alloy the crack initiation for the two samples at 100,000 and 250,000 cycles for the two samples, 5052 and 6061 were based on the experimental results as shown in figs. (10–13). in contrast to the crack that occurred in sample 6061, which could be difficult to observe with the naked eye because of the molecular characteristics of the material, the shape of the crack in sample 5052–aa was often plainly apparent and contains si... fig. 14. crack propagation in alloys experimentally: a. alloy 5052-aa; b. alloy 6061-aa in contrast, the crack that formed in sample 6061 was difficult to notice with the naked eye, as shown in fig. 14. initially, an agreement in the prediction of the findings could be observed and used to examine the relation between the length of the c... fig. 15. crack growth steps in 5052-aa. fig. 16. crack growth steps in 6061-aa. when the number of cycles is increased, a difference can be observed between the experimental and theoretical curves. the reason for this difference is due to the nature of the material [26] in the experimental test; the material used was a commercial... 5. conclusion  the experimental results are consistent with the mathematical model developed for the research. the estimate of a crack growing in the material at the beginning of the chart indicates the connection between the length of the fracture and the number ...  it was shown from the procedures of studying experimental fatigue test methods for cyclic loads on materials that the initiation of crack for sample 6061 was larger than that for sample 5052 by a percentage equal to 60%.  the experimental work shows the rate of crack growth in sample 6061 aa was lower than the rate of crack growth in sample 5052 aa. this finding implies that sample 6061 requires more time than sample 5052 to reach the failure stage, also known as mec...  based on the composition of the chemical properties of the samples and the rate of crack growth, it can be inferred that the samples within aluminium alloy 6061 are ductile material alloys with relatively small grain size. this characteristic explai...  in contrast to sample 5052, which is defined by big grains, the speed of spread of the crack and the great distance to the crack that grew, this sample is distinguished by the type and shape of the crack that formed within it, which is specified as...  some influencing variables, in addition to the basic nature of the alloy’s elemental makeup, are responsible for the difference that may be observed between the experimental and theoretical results at the end of the crack formation process.  a comparison of the analytical findings for alloy 5052 with the experimental result indicated the analytical model with the error rate in crack growth rate is 5.23%. the percentage of error for alloy 6061 is 17.5%, which is a good estimate for estim...  the c and m values found for the paris relation crack propagation through the application of the logarithmic diagram are at acceptable levels within the ranges that aluminium alloys have defined for themselves. nomenclature and units declaration of interest the authors declare that they have no conflicts of interest financial or personal relationships with other persons or organisations that could improperly influence their work in connection with the publication of this article. submission declaration the authors declare that the work described has not been previously published, that it is not under consideration for publication elsewhere, and that all authors have approved its publication in connection with the publication of this article. acknowledgement we thank everyone who have helped publish this study. we also thank the mechanical department at baghdad university for providing us with the resources and assistance to finish this project. finally, we appreciate all research participants’ time and w... funding sources this research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. references [1] p. zhang, j. li, y. zhao, and j. li, “crack propagation analysis and fatigue life assessment of high-strength bolts based on fracture mechanics.,” sci. rep., vol. 13, no. 1, p. 14567, sep. 2023, doi: 10.1038/s41598-023-41804-z. 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[online]. available: https://books.google.iq/books?id=7kozdwaaqbaj [25] t. baral, paris’ law parameters estimation for fatigue crack prediction of an aluminum alloy plate under cyclic loading. university of manitoba, 2022.https://books.google.iq/books?id=commzweacaaj [26] d.-c. ko, d.-h. ko, j.-h. kim, and j.-h. park, “development of a partition panel of an al6061 sheet metal part for the improvement of formability and mechanical properties by hot forming quenching,” adv. mech. eng., vol. 9, no. 2, p. 168781401769... دراسة معدلة لتأثير الاحمال المركبة بتسليط حمل الشد الثابت مع القص الدوري على انتشار تشققات الحواف الديناميكية في صفيحة رقيقة من الألومنيوم اسراء عبد الرزاق مصلح1* فتحي عبد الصاحب الشماع2 1 ،2 قسم هندسة الميكانيك، كلية الهندسة، جامعة بغداد، العراق *البريد الالكتروني : israa.mosleh2003m@coeng.uobaghdad.edu.iq المستخلص نظرا للأهمية والمخاطر المحتملة المرتبطة بحدوث الشقوق الميكانيكية في التطبيقات الهندسية الهامة، فقد أصبح من الضروري البحث عن نوع معين من انتشار الشقوق. هذه هي حالة شقوق الوضع المختلط التي تنتج عن الوضع الأول والوضع الثاني للتحميل والتي تنتشر في معظم ال... this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312–0789 vol. 21, no. 1, march (2025), pp. 61– 72 improving the performance of steering by wire using a model predictive controller enhanced with particle swarm optimisation taher sachit taher1, ali hussien mary2*, furat ibrahim hussein3, mohammed ghufran khidhir abboosh4 and muhammad umar fareed5 1,2,3 department of mechatronics engineering, al-khwarizmi college of engineering, university of baghdad, baghdad, iraq 4 department of data science and visualization, university of debrecen, hungary 5 wakefield college, wakefield, england *corresponding author’s email: alimary76@kecbu.uobaghdad.edu.iq (received 7 august 2024; revised 28 december 2024; accepted 27 january 2025; published 1 march 2025) https://doi.org/10.22153/kej.2025.01.002 abstract the challenges of steering-by-wire (sbw) systems in vehicles are due to the absence of a direct mechanical link between the steering wheel and the wheels on the road. this limitation imposes the necessity of employing sophisticated control systems to attain the highest accuracy and stability during operation. in such systems, the responsibility rests completely on the utilised controller to change the wheel’s angle on the road swiftly and accurately in response to the steering wheel changes by the driver. however, conventional control systems suffer slowly in responding to instructions and some fixed errors in their steady-state phase. the current study introduces an innovation of a model that integrates model predictive control (mpc) with particle swarm optimisation (pso) to improve the performance of sbw systems. the mpc procedure is typically employed to control system responses over a timeframe and eliminate unnecessary and ineffective actions according to the specified objectives. the pso algorithm is used to manage the ineffective parameters within the mpc. results revealed that the proposed approach remarkably and effectively shortens response time, enhances wagon stability and reduces the settling error to nearly null. in addition, the integration of pso with the overall system performance enhances the tuning of the response time, hence augmenting the system efficiency and responsiveness. the study outcomes support the proposal that the control strategy can improve the efficiency of sbw systems with high operational goals. keywords: steering by wire; vehicle; model predictive controller; particle swarm optimisation; controller. 1. introduction steering-by-wire (sbw) systems are a promising steering system technology in the field of automotive and transportation industry. such systems found their way largely into automatic guided vehicle (agv) systems, fork lifters and many material handling instrument control strategies that have been implemented over the years to improve their performance. sbw does away with the direct mechanical hardware between the steering wheel and the wheels on the road. this innovation must be precise enough and has an extremely fast response speed to ensure highresolution operational performance, which will satisfy drivers and users whilst ensuring safety [1]. early sbw systems used classic proportional integral derivative (pid) controllers, which provide acceptable performance for numerous linear systems. when they are integrated with nonlinearities and time delays or applied in changing operating conditions, they lose their mailto:alimary76@kecbu.uobaghdad.edu.iq https://doi.org/10.22153/kej.2025.01.002 taher sachit taher al-khwarizmi engineering journal, vol. 21, no.1, pp. 6172 (2025) 62 efficiency. åström et al. and mary et al. [2–3] stated that pid controllers usually do not work well in dynamic environments due to their issues with stability and accuracy, which affect error rate growth. fuzzy logic controllers are more suitable for complex and nonlinear systems because of their ability to tolerate instability and loss choices. mitra and kumar [4] improved the flexibility and robustness of fuzzy logic controllers in sbw systems, especially under the conditions of long disturbances and disturbing impacts. despite these exceptional features, the layout of lean logic controllers can be troublesome, and fine-tuning them is necessary to ensure proper use [5]. flexible control strategies are created as a response to the shortcomings of traditional control procedures. adaptive control frameworks robustly change their parameters to adapt to modifications in dynamic systems [6]. the use of adaptive control in many applications has improved accuracy and robustness against disturbances [7–8]. similarly, gao et al. [9] studied the integration of adaptive control into robotic systems, which resulted in enhanced efficiency and reduced error rates. using console-based artificial intelligence, such as neural networks, deep learning and reinforcement learning, can enhance responsiveness to data and improve performance over time; however, it requires substantial computing power and massive training data [10]. the most prominent advanced control technology used to improve the performance of transmission lines is model predictive control (mpc). it represents a control strategy that can deal with a wide range of constraints and achieve the optimal performance in dynamic environments. mpc operates by predicting the enduring temporal behaviour of the framework based on a scientific model and thereafter determining the most suitable control strategies to achieve the desired performance. control activities occur intermittently, enabling the system to repair deviations and maintain the target state efficiently. mpc has been utilised in various contexts, including its implementation in thermal management systems for business process optimisation, thereby enhancing system stability and reducing energy consumption in automotive systems [7]. it works by anticipating the longstanding time behaviour of the framework based on a scientific demonstration and then calculating the foremost fitting control methods to realise the focus on execution. control activities happen intermittently, permitting the framework to rectify deviations and keep up the target state productively. mpc has been used in several settings, proven using mpc in thermal management structures in business procedure manipulate [11], which stepped forward system stability and decreased electricity consumption in car systems [12] showed that mpc can provide an automotive manipulate gadget advanced in the field of robotics [13]. for direction planning and impediment avoidance based totally on mpc, leading to green and safe robots[14]. ates et al. [15] tested the usage of mpc in thermal control structures, which showed high adaptability to surprising environmental adjustments, improving gadget stability and reducing energy intake. similarly, ye et al. [16] showed that mpc can enhance the performance of visitor control systems, thereby improving highquality-grained making plans and rapid reaction to adjustments in overall performance. particle swarm optimisation (pso) is a popular algorithm specifically designed for the social behaviour of birds and fish. it enhances problem solving by allowing proposed solutions, known as particles, to move in the search space in line with simple mathematical principles based on their most useful function and the optimal function of the system. therefore, this collective behaviour contributes to finding the most useful solution efficiently. it has demonstrated efficacy in addition to systems that improve management systems in many packages. pso has been used to optimise the control parameters of automated drive structures [17], resulting in improved accuracy and responsiveness. in power structures, pso is used to enhance load distribution hassles, obtaining improved performance and electrical efficiency [18], [15], [19]. kumar and sharma [20] tried optimising the mpc parameters using pso, thereby improving overall implementation at scale and reaching faster response states and better tuning in active situations. based on these effects, this consideration suggests combining mpc and pso to increase the dominant control framework. a mathematical model of the device can be developed [21], and its performance can be analysed using mpc, with pso used to optimise control parameters. the abovementioned integrated approach is expected to enhance the device’s high accuracy and responsiveness, giving it extraordinarily high effectiveness in commercial and transportation software. the integration of mpc and pso provides a synergistic effect, combining the predictive and constraint processing skills of mpc with the optimisation ability of pso. this technique has a high ability to overcome many challenging situations in the sbw system, including dealing with nonlinearities, uncertainties and taher sachit taher al-khwarizmi engineering journal, vol. 21, no.1, pp. 6172 (2025) 63 external disturbances. by leveraging the strengths of both technologies, the proposed controller aims to have superior overall performance and reliability. the effectiveness of mixing mpc and pso has been explored in many research. huang et al. [22] conducted a comparative assessment of assembled optimisation calculations comprising pso in tuning mpc parameters for chemical system organisation, thus determining crucial developments in execution estimations. in the setting of sbw systems, yan et. al. [23] reviewed the application of mpc for road checking in agvs, fulfilling tall exactness and quality to unsettling impacts. complementarily, tavoosi et al. [24] utilised pso to make strides in the course arrangement of agvs, resulting in smoother and more proficient directions. the present study aims to develop and evaluate a mathematical model concentrating on applying mpc-pso in sbw systems. the objective is to expect and control system conduct, using pso to optimise mpc management parameters and comparing the performance of the included machine through simulations and experimental verification. a complex control system that remarkably fulfils the accuracy and responsiveness demands of advanced commercial and transportation solutions is expected. 2. modelling of sbw systems the hardware of sbw systems has three fundamental subsystems, each containing many sensors or actuators, as shown in figure 1. the assembly of the steering wheel, the front wheel subsystem and some additional mechanical hardware. the guidance wheel includes a torque sensor, a steering attitude sensor and maybe a movement encoder. the front wheel system accommodates an angle sensor, a motor encoder, rack equipment and additives of the wheel suspension system. fig. 1. steering-by-wire system [2] steering wheelthe modelling of 2.1 a schematic of the steering wheel assembly in figure 2 indicates that the system is associated with many considered variables, i.e., steering angle, steering motor angle and current, with other inputs including motor voltage, input angle, torque and friction torque produced during wheel rotation. the system’s dynamic model can be expressed in accordance with newton’s laws, as shown in the series of equations below. the angle of the steering wheel, the angular displacement of the steering motor and the steering motor current can be stated as [21] ӫ𝑠 = 1/𝐽𝑠(𝑇𝑑𝑟𝑖𝑣𝑒𝑟 − 𝑇𝑓𝑟𝑖𝑐𝑡𝑖𝑜𝑛 − 𝑏𝑠𝑐 ∗ ө̇𝑠 − 𝑘𝑠 ∗ ө𝑠 + 𝑏𝑠𝑐 ∗ ө̇𝑚1 + 𝑘𝑠 ∗ ө𝑚1 ) , … (1) ӫ𝑠 = 1/𝐽𝑠(𝑇𝑑𝑟𝑖𝑣𝑒𝑟 − 𝑇𝑓𝑟𝑖𝑐𝑡𝑖𝑜𝑛 − 𝑏𝑠𝑐 ∗ ө̇𝑠 − 𝑘𝑠 ∗ ө𝑠 + 𝑏𝑠𝑐 ∗ ө̇𝑚1 + 𝑘𝑠 ∗ ө𝑚1 ) , …(2) 𝑑𝑖1 𝑑𝑡 = 1/𝐿1(−𝑅1 ∗ 𝑖1 − 𝐾𝑏1 ∗ ө̇𝑚1 + 𝑉𝑠1) , …(3) taher sachit taher al-khwarizmi engineering journal, vol. 21, no.1, pp. 6172 (2025) 64 fig. 2. steering wheel subsystem diagram [25] torque of steering motor [26] 𝑇𝑚1 = 𝐾𝑡 ∗ 𝑖1. … (4) accordingly, the state space representation of the steering wheel system can be expressed as follows: �̈�(𝑡) = 𝐴𝑠 𝑋(𝑡) + 𝐵𝑠 𝑈(𝑡), … (5) output 𝑦(𝑡) = 𝐶𝑠 𝑋(𝑡) + 𝐷𝑠 𝑈(𝑡), … (6) state 𝑋(𝑡) = [ө𝑠 ө̇𝑠 ө𝑚1 ө̇𝑚1 𝑖1 ] 𝑇 . … (7) the inputs include the driver torque (𝑇𝑑𝑟𝑖𝑣𝑒𝑟 ), friction torque (𝑇𝑓𝑟𝑖𝑐𝑡𝑖𝑜𝑛 ) and motor voltage (𝑉𝑠1 ): 𝑈(𝑡) = [𝑇𝑑𝑟𝑖𝑣𝑒𝑟 𝑇𝑓𝑟𝑖𝑐𝑡𝑖𝑜𝑛 𝑉𝑠1 ] 𝑇 , … (8) 𝐴𝑠 = [ 1 0 0 0 0 (− 𝐾𝑠 𝐽𝑠 ) (− 𝑏𝑠𝑐 𝐽𝑠 ) (𝐾𝑠 𝐽𝑠 ) (𝑏𝑠𝑐 𝐽𝑠 ) 0 0 0 0 1 0 ( 𝐾𝑠 𝐽𝑚1 ) (− 𝑏𝑠𝑐 𝐽𝑚1 ) (− 𝐾𝑠 𝐽𝑚1 ) (− (𝑏𝑚1+𝑏𝑠𝑐) 𝐽𝑚1 ) 0 0 0 0 (−𝐾𝑏1 𝐿1 ) (−𝑅1 𝐿1 )] , …(9) 𝐵𝑠 = [ 0 0 ( (𝑇𝑑𝑟𝑖𝑣𝑒𝑟−𝑇𝑓𝑟𝑖𝑐𝑡𝑖𝑜𝑛) 𝐽𝑠 ) 0 0 0 0 0 0 ( 1 𝐿1 ) ] ) 10…( the angle and current of the steering motor are the outputs of the system. 𝐶𝑠 = [ 0 0 1 0 0 0 0 0 0 1 ] … (11) 𝐷𝑠 = 0 where ө𝑠 (degree) is the angular displacement of the steering wheel, ө𝑚1 (degree) is the angular displacement of the front wheel motor, 𝑖1 (a) is current of steering motor, ks (n.m/rad) is lumped torque stiffness, bsc (n.ms/rad) is steering column damping, bm1 (n.m.s/rad) is motor damping, js (kg.m2) is steering lumped inertia, jm1 (kg.m2) is steering motor inertia, kb1 (v) is steering motor emf constant, l1 (h) is steering motor electrical inductance and r1 (ohm) is steering motor electrical resistance. 2.2 front wheel subsystem modelling as shown in figure 3, the yaw angle (𝛾𝑟𝑎𝑐𝑘 ), front wheel angle (𝛿𝑓 ) and front motor angle (ө𝑚2 ) are the key variables in representing the front wheel subsystem. the force of the rack and the angle of the front tire can be represented by [27]: �̇�𝑟𝑎𝑐𝑘 = − 𝑏𝑟 𝑚𝑟 𝛾𝑟𝑎𝑐𝑘 − ө𝑚2 𝐶𝑚2∗𝑔𝑚 − 𝑔𝑟 𝑐𝑡 𝑣𝑡 … (12) �̇�𝑓 = − 𝐵𝑡 𝐽𝑡 𝛿𝑓 + 𝑣𝑡 𝑐𝑡 … (13) fig. 3. the front wheel subsystem diagram [25]. the current, torque, angular displacement of the front motor and velocity of the tire rod are stated as [27]: 𝑑𝑖2 𝑑𝑡 = 1/𝐿2(−𝑅2 ∗ 𝑖2) − 𝐾𝑏2 𝐽𝑚2 ∗ t𝑚2 + 𝑉𝑠2 … (14) �̇�𝑚2 = 𝑘𝑏2 𝐿2 ∗ 𝑖2 − 𝑏𝑚2 𝐽𝑚2 ∗ t𝑚2 − ө𝑚2 𝐶𝑚2 … (15) ө̇𝑚2 = 𝑇𝑚2 𝐽𝑚2 + 𝛾𝑟𝑎𝑐𝑘 𝑚𝑟∗𝑔𝑚 … (16) taher sachit taher al-khwarizmi engineering journal, vol. 21, no.1, pp. 6172 (2025) 65 �̇�𝑡 = 𝛾𝑟𝑎𝑐𝑘 𝑚𝑟∗𝑔𝑟 − 𝑣𝑡 𝑗𝑡 … (17) the state space model of the front wheel subsystem is �̈�(𝑡) = 𝐴𝑓 𝑋(𝑡) + 𝐵𝑓𝑈(𝑡) . … (18) the output angle of the steering motor represents the input to the front wheel subsystem: 𝑈(𝑡) = [ ө𝑚1 ]𝑇. the output and state of the front wheel subsystem: 𝑦(𝑡) = 𝐶𝑓𝑋(𝑡) + 𝐷𝑓 𝑈(𝑡) … (19) 𝑋(𝑡) = [𝑖2 𝑇𝑚2 𝛾𝑟𝑎𝑐𝑘 𝛿𝑓 ө𝑚2 𝑣𝑡 ]𝑇 … (20) the outputs of the front wheel system are the front motor angle and the wheel angle: 𝐴𝑓 = [ (− 𝑅2 𝐿2 ) (− 𝐾𝑏2 𝐽𝑚2 ) 0 0 0 0 (𝐾𝑏2 𝐿2 ) (− 𝑏𝑚2 𝐽𝑚2 ) 0 0 (− 1 𝐶𝑚2 ) 0 0 0 0 (− 𝐵𝑡 𝐽𝑡 ) 0 ( 1 𝐶𝑡 ) 0 ( 1 𝐽𝑚2 ) (− 1 𝑔𝑚+𝑚𝑟 ) 0 0 0 0 0 ( 1 𝑔𝑟+𝑚𝑟 ) (− 1 𝐽𝑡 ) 0 0 ] , …(21) 𝐵𝑓 = [ 1 0 0 0 0] , … (22) 𝐶𝑓 = [ 0 0 0 1 0 0 0 0 0 0 1 0 ] , … (23) 𝐷𝑓 = 0, where br (n.m/rad) is the resistance rack, mr (kg) is the mass rack, cm2 (n.m/s) is the front motor shaft compliance, gm (m) is the column pinion radius, gr (m) is the length ratio steering arm, ct (rad/n.m) is the compliance of the tire rod, bt (n.m.s/rad) is the resistance of the tire rod, jt (kg.m2) is the inertia of tire, vt (km/h) is the tire rod velocity, kb2 (v) is the front-wheel motor emf constant, jm2 (kg.m2) is the front motor inertia, and bm2 (n.m.s/rad) is the front motor damping. 3. controller design this stage discusses the plan of a controller that coordinates mpc with pso to obtain accurate and appropriate control over the routing framework. this approach leverages the prescient and controlling gifts of mpc in conjunction with the parameter optimisation qualities of pso to pick up the most dependable execution. 3.1 mpc algorithm one effective and adaptable control method that is frequently applied to dynamic systems is mpc. it works especially well in situations such as sbw systems where managing restrictions is essential. using a mathematical model, mpc forecasts a system’s future behaviour and determines the best course of action for control to reach the intended performance. to minimise a cost function, which usually represents the departure from the intended system trajectory whilst considering system restrictions, mpc solves an optimisation problem at each time step. this control strategy is based on the representation of system dynamics using a state space model. the basic model utilised in mpc, which is typically described in the state space form, must be presented before going into the specific mathematical formulation. the system dynamics in mpc consists of system matrices a,b,and c[7][8][11][15]: 𝑍𝑘+v|𝑘 = 𝐶𝐴𝑣𝑋𝑘 + [c𝐴𝑣−1 𝐶𝐴𝑣−2𝐵 …𝐶𝐴𝐵 𝐶𝐵] [ 𝑈𝑘|𝑘 𝑈𝑘+1|𝑘 𝑈𝑘+2|𝑘 . . . 𝑈𝑘+𝑣−2|𝑘 𝑈𝑘+𝑣−1|𝑘 ] , … (24) [16] where 𝑍𝑘 ∈ ℝ𝑟 is the output that needs to be controlled, and 𝑣 is the control horizon. the predictive for the final step (k+f) can be obtained by 𝑍𝑘+f|𝑘 = 𝐶𝐴𝑓𝑋𝑘 + [c𝐴𝑓−1 𝐶𝐴𝑓−2𝐵 … 𝐶𝐴𝑓−𝑣+1𝐵 𝐶𝐴�̅�,𝑣𝐵] [ 𝑈𝑘|𝑘 𝑈𝑘+1|𝑘 𝑈𝑘+2|𝑘 . . . 𝑈𝑘+𝑣−2|𝑘 𝑈𝑘+𝑣−1|𝑘 ] , … (25)[16] 𝑍 = 𝑂𝑋𝑘 + 𝑀𝑈 , … (26)[16][19] taher sachit taher al-khwarizmi engineering journal, vol. 21, no.1, pp. 6172 (2025) 66 𝑍 = [ 𝑍𝑘+1|𝑘 𝑍𝑘+2|𝑘 𝑍𝑘+3|𝑘 . . 𝑍𝑘+𝑣|𝑘 𝑍𝑘+𝑣+1|𝑘 . . 𝑍𝑘+𝑓|𝑘 ] , 𝑈 = [ 𝑈𝑘|𝑘 𝑈𝑘+1|𝑘 𝑈𝑘+2|𝑘 . . . 𝑈𝑘+𝑣−2|𝑘 𝑈𝑘+𝑣−1|𝑘] , 𝑂 = [ 𝐶𝐴 𝐶𝐴2 𝐶𝐴3 . . 𝐶𝐴𝑣 𝐶𝐴𝑣+1 . . 𝐶𝐴𝑓 ] , … (27)[20] m= [ 𝐶𝐵 0 0 0 … 0 𝐶𝐴𝐵 𝐶𝐵 0 0 … 0 𝐶𝐴2𝐵 𝐶𝐴𝐵 𝐶𝐵 0 … 0 . . . . . . . . . … … . . . 𝐶𝐴𝑣−1𝐵 𝐶𝐴𝑣−2𝐵 𝐶𝐴𝑣−3𝐵 … 𝐶𝐴𝐵 𝐶𝐵 𝐶𝐴𝑣𝐵 𝐶𝐴𝑣−1𝐵 𝐶𝐴𝑣−2𝐵 … 𝐶𝐴2𝐵 𝐶𝐴̅ 1,𝑣𝐵 . . . . . . . . . . . . … . . . 𝐶𝐴𝑓𝐵 𝐶𝐴𝑓−1𝐵 𝐶𝐴𝑓−2𝐵 … 𝐶𝐴𝑓−𝑣+1𝐵 𝐶𝐴̅ 𝑓,𝑣 𝐵] , … (28)[22] where m is a state prediction matrix. let these desired outputs be denoted by 𝑍𝑑 𝑘+1, 𝑍 𝑑 𝑘+2, 𝑍 𝑑 𝑘+3, …… … . , 𝑍𝑑 𝑘+𝑓 , … (29)[23] 𝑍𝑑 = [ 𝑍 𝑑 𝑘+1 𝑍𝑑 𝑘+2 𝑍𝑑 𝑘+3 . . . . 𝑍𝑑 𝑘+f ] . … (30)[28] the cost function can be expressed as [29] 𝑚𝑖𝑛𝑈 ‖𝑍𝑑 − 𝑍‖2 = 𝑚𝑖𝑛𝑈 (𝑍𝑑 − 𝑍) 𝑇 (𝑍𝑑 − 𝑍). … (31) by substituting 𝑍𝑑and 𝑍, the final form of the cost function that will penalise the inputs becomes clear as shown in the following equation: 𝐽𝑈 = 𝑈𝑇𝑊3𝑈, … (32) where ju is a cost function for control input, u is an input vector control, and w3 is a final weighting matrix. 𝑊3 = 𝑊𝑇 1𝑊2𝑊1 … (33)[30][7] 𝑊2 = [ 𝑄0 0 0 . . . . 0 0 𝑄1 0 . . . . 0 0 . . . . . . . 0 . . . . . . . . . . . . . . . . . . 0 0 0 . . . . 𝑄𝑣−1 ] … (34) matrix dimensions are 𝑊2 = [𝑚 ∗ 𝑛,𝑚 ∗ 𝑛], where w1, w2, m and n are the state prediction matrix, input weight matrix, number of outputs and number of inputs, respectively. the cost function that corresponds to the tracking error is 𝐽𝑧 = (𝑆 − 𝑀𝑈)𝑇𝑊4( 𝑆 − 𝑀𝑈), … (35)[7] where ( 𝑆 = 𝑍𝑑 − 𝑂𝑋𝑘 ). the cost function penalises the difference between the desired and controlled trajectory as shown in the following equation [7]: 𝑚𝑖𝑛𝑈 𝐽𝑧 + 𝐽𝑈 . … (36) by partial derivative of the cost function for u, 𝜕𝐽 𝜕𝑈 = −2𝑀𝑇𝑊4 + 2𝑀𝑇𝑊4𝑀𝑈 + 2𝑊3𝑈 . … (37) to find the minimum of the cost function for u, 𝜕𝐽 𝜕𝑈 = 0. … (38) 𝜕𝐽 𝜕𝑈 = −2𝑀𝑇𝑊4 + 2𝑀𝑇𝑊4𝑀𝑈 + 2𝑊3𝑈 = 0. … (39) from equation (39), the solution of the mpc is �̌� = (𝑀𝑇𝑊4 𝑀 + 𝑊3)𝑀 𝑇𝑊4 𝑆. … (40) the initial parameters of the mpc were selected on the basis of theoretical practices that fit the system parameters and through manual tuning in the early simulation stages. however, pso was later applied to tune these parameters automatically to improve the performance further and ensure optimal parameter selection, thus improving the speed and accuracy of the sbw system. 3.2 pso algorithm the pso algorithm can be utilised to find optimal values in various applications, most notably in pid controllers [31] [32]. however, it is rarely used in the mpc approach. pso calculation is used in finding the optimal values of the weight matrix w2, which provides accuracy and speed in reaching these values [18][19][26][33][34]. as depicted in figure 4, the pso process iteratively updates the position and velocity of each particle. each particle tracks two key metrics: 𝑃𝑏𝑒𝑠𝑡 : the particle’s best-known position based on its objective function 𝑔𝑏𝑒𝑠𝑡 : the best position discovered by the entire swarm these metrics are critical in guiding particles towards the global optimum. the inertia weight, also shown in figure 4, controls the balance between exploration and exploitation. the inertia weight is ∅ = ∅𝑚𝑎𝑥 − (∅𝑚𝑎𝑥−∅𝑚𝑖𝑛 𝑇𝑚𝑎𝑥 ) . … (41)[35] let x and v be the position and velocity respectively. taher sachit taher al-khwarizmi engineering journal, vol. 21, no.1, pp. 6172 (2025) 67 the equations for updating the velocity and position are as follows: 𝑣(𝑖,𝑙) (𝑡) = ∅𝑣(𝑖,𝑙) (𝑡 − 1) + 𝑐1𝑟1 (𝑃𝑏𝑒𝑠𝑡 − 𝑥(𝑖,𝑙) (𝑡 − 1)) + 𝑐2𝑟2 (𝑔𝑏𝑒𝑠𝑡 − 𝑥(𝑖,𝑙) (𝑡 − 1)), … (42)[36] 𝑥(𝑖,𝑙)(𝑡) = 𝑥(𝑖,𝑙)(𝑡 − 1) + 𝑣(𝑖,𝑙)(𝑡), … (43)[36] where 𝑐1, 𝑐2,𝑖, 𝑙 are the individual and social cognitive, number of particles and number of variations, respectively, and 𝑟1, 𝑟2 are uniformly distributed randomly. 𝑄0 , …, 𝑄𝑣−1 are values of the weight matrix, updated with each iteration in the partial swarm algorithm, reaching the optimal values within the predefined constraints [37][38][22]. 𝑄0 = 𝑥(𝑖,1) , 𝑄𝑣−1= 𝑥(𝑖,𝑚∗𝑛) fig. 4. flowchart of pso table 1, parameters of pso parameter value note 𝑐1, 𝑐2 2.0 this value represents a good balance between relying on individual experiences and global search 𝑟1 , 𝑟2 random numbers )0,1( between to introduce behaviourstochastic ∅ 0.9 to control the between balance exploration and exploitation 4. results and discussion 4.1 steering wheel simulation the simulation was conducted on a windows 10 pc, offering a reliable environment suitable for operating the python 2022 programming environment. the values mentioned in table 3[27] were adopted as a basis for simulating the system in the absence of the pso algorithm for the steering wheel system. the initial values of qo and q1,v−1 equal to 10−10 and 10−9 respectively were chosen on the basis of the experimental tuning to balance the speed and stability in the system response as these values help in reducing overshoot whilst ensuring fast convergence. in addition, the constraints of the pso algorithm were determined for the values [maximum value (10−10, 10−2), minimum value (10−20, 10−8). these constraints were chosen to ensure that the optimisation process remains within the possible and practical ranges of the system operating parameters, thus avoiding unrealistic or unstable solutions. the pso results for the weight values qo and q1,v−1 are 2.9×10−4 and 5.1×10−13, respectively. 4.1.1 cases of step and square response figure 5 graphs the step response for the angle of steering motor qm1. the use of pso with mpc has remarkably improved the angle in terms of the settling time, which decreased from 2.096 seconds to 0.268 seconds, and overshoot decreased from 6.524% to almost 0%, as shown in table 2. the degree of enhancement is evident in the ability to manage a square response, as illustrated in figure 6. taher sachit taher al-khwarizmi engineering journal, vol. 21, no.1, pp. 6172 (2025) 68 fig. 5. step response for the angle of a steering motor ө𝒎𝟏 fig. 6. square response for the angle of a steering motor ө𝒎𝟏 4.2 front wheel simulation in the front wheel system, the values for the weight matrix qo and q1,v−1 equal to 10−6 and 10−3 respectively were employed, with constraints between a maximum of 10−20, 10−10 and a minimum of 10−25, 10−15. the obtained result of pso for the weight values for the weight values qo and q1,v−1 are 8.93×10−12 and 9.72×10−16, respectively. 4.2.1 cases of step and square response figure 7 shows the improvements in the angle of the front wheel motor qm2 when the pso has integrated with mpc. figure 8 shows a clear improvement in the settling time, and the rise time and the angle of the front tire δf can be noticed. the level of improvement appears with the same ability to deal with a square response, as shown in figures 9 and 10. fig. 7. step response for the angle of the front wheel motor ө𝒎𝟐 fig. 8. step response for the angle of the front tire 𝜹𝒇 fig. 9. square response for the angle of the front wheel motor ө𝒎𝟐 fig. 10. square response for the angle of the front tire 𝜹𝒇 . taher sachit taher al-khwarizmi engineering journal, vol. 21, no.1, pp. 6172 (2025) 69 comparing the results shown in table 2 with those referenced in [19], which are considered the closest research in terms of the factors that can be compared, especially the angle of the front tire δf, revealed an improvement in settling time or overshoot. the stability time for the tire angle is 1 second, and the highest peak is 19%. the use of mpc enhanced by pso improves this substantially, where the stability time became 0.06 seconds and the highest peak reached 0.013%, as presented in table 2. the mpc was trained offline using simulation data, allowing for improved tuning of parameters and testing of different scenarios before real-time implementation. the pso algorithm was used in this offline phase to optimise the mpc parameters for robust real-time control. 5. conclusion the following points represent the conclusive findings from the present study: 1. the proposed system showed quick response through a reduction in the response time and increasing the reasonableness of real time. 2. the system focused on the mo steady state, providing high accuracy in reaching the required values without identifiable overshoot or direct safety. 3. by taking the stride of implementation indicators such as iae and itae, pso computation advances the implementation of the insight controller, making the framework more productive and responsive. 4. the frame is a suitable choice for steering systems in automobiles and other instruments that require precise control. 5. results demonstrate good suitability for applications requiring accurate and fast responses. furthermore, the future controller enhanced by pso provides a good, reliable and efficient model for driving sbws. it achieves high accuracy and fast response time in a range of real-world applications, remarkably enhancing the overall performance. 6. future development proposal one suitable proposal for future development of the research topic is to integrate adaptive or machine learning algorithms with pso to adjust parameters in real time, which helps enhance control over disturbances and changing conditions and achieve the necessary robustness. moreover, testing on real vehicles can further prove the robustness and reliability of the vehicle, offering ideas for useful implementation in automotive systems. table 2, performance indexes performance measures mpc without pso mpc with pso ө𝒎𝟏 ө𝒎𝟐 𝜹𝒇 ө𝒎𝟏 ө𝒎𝟐 𝜹𝒇 settling time (s) 2.096 0.344 3.939 0.268 0.086 0.060 rise time (s) 1.525 0.188 0.922 0.179 0.069 0.048 overshoot % 6.524 −0.001 11.315 −1.275ᵡ 10−8 1.632ᵡ 10−8 0.013 iae 1.199 0.093 1.051 0.090 0.043 0.030 itae 1.710ᵡ 10−6 0.0001 0.066 6.969ᵡ 10−12 3.893ᵡ 10−10 1.747ᵡ 10−7 table 3, steering-by-wire system parameters bil items values bil items values ө𝑠 angular displacement of steering wheel (degree) _ t𝑚2 front motor torque (n.m) _ 𝑘𝑠 lumped torque stiffness (n.m/rad) 3500 𝑘𝑏2 front motor emf constant (v) 2.0 𝑏𝑠𝑐 steering column damping (n.ms/rad) 0.136 𝑏𝑚2 front motor damping (n.m.s/rad) 1.0 taher sachit taher al-khwarizmi engineering journal, vol. 21, no.1, pp. 6172 (2025) 70 𝐽𝑠 steering lumped inertia (kg.m2) 0.0079 𝐶𝑚2 front motor shaft compliance (n.m/s) 0.4 ө𝑚1 angular displacement of front wheel motor (degree) _ 𝛾𝑟𝑎𝑐𝑘 rack force (n.m) _ 𝑏𝑚1 motor damping (n.m.s/rad) 0.05 𝑏𝑟 resistance rack (n.m/rad) 25 𝐽𝑚1 steering motor inertia (kg.m2) 2.0 𝑚𝑟 mass rack (kg) 2.0 𝑇𝑑𝑟𝑖𝑣𝑒𝑟 torque of driver (n.m) 2.0 𝑣𝑡 tire rod velocity (km/h) _ 𝑇𝑓𝑟𝑖𝑐𝑡𝑖𝑜𝑛 torque of friction (n.m) 0.2 𝑐𝑡 compliance of tire rod (rad/n.m) 0.2 𝑇𝑚1 steering motor torque (n.m) _ 𝑔𝑟 length ratio steering arm (m) 4.5 𝐿1 steering motor electrical inductance (h) 0.0002 𝑔𝑚 column pinion radius (m) 0.015 𝑅1 steering motor electrical resistance (ohm) 4.6 𝐵𝑡 resistance of tire rod (n.m.s/rad) 0.004 𝑖1 current of steering motor (a) _ 𝐽𝑡 inertia of tire (kg.m2) 1.36 𝑉𝑠1 power supply 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(2025) 72 -61، صفحة 1، العدد21مجلة الخوارزمي الهندسية المجلد طاهر ساجت طاهر 72 وحدة التحكم التنبؤية تحسين أداء التوجيه عن طريق األسالك باستخدام psoالمعززة بخوارزمية تحسين سرب الجسيمات mpcللنموذج ، 3فرات ابراهيم حسين، 2*علي حسين مري ، 1طاهر ساجت طاهر 5محمد عمر فريد ، 4محمد غفران خضر عبوش ، بغداد ، العراقجامعة بغداد، كلية الهندسة الخوارزمي، قسم هندسة الميكاترونيكس 1،2،3 المجر ،جامعة ديبريسين ،قسم علوم البيانات والتصور 4 انجلترا، ويكفيلد، كلية ويكفيلد 5 alimary76@kecbu.uobaghdad.edu.iqالبريد االلكتروني: * المستخلص في المركبات ذات التوجيه ترجع إلى غياب الرابط الميكانيكي المباشر بين عجلة القيادة والعجالت )sbw (إن التحديات التي تواجه أنظمة التوجيه باألسالك مة، تقع المسؤولية على الطريق. هذا االمر يفرض ضرورة استخدام أنظمة تحكم متطورة لتحقيق أعلى درجات الدقة واالستقرار أثناء التوجيه. في مثل هذه األنظ المستخدمة لتغيير زاوية العجلة على الطريق بسرعة ودقة استجابة لتغييرات عجلة القيادة من قبل السائق. ومع ذلك، تعاني أنظمة بالكامل على وحدة التحكم نموذج يدمج ة ابتكاًرا لالتحكم التقليدية من بطء شديد في االستجابة للتعليمات مصحوبة ببعض األخطاء الثابتة في مرحلة الحالة المستقرة. تقدم الدراسة الحالي ( mpc)لتحسين أداء أنظمة التوجيه باألسالك. يتم استخدام إجراء وحدة التحكم التنبؤية بالنموذج ( pso)التحكم التنبئي بالنموذج مع تحسين سرب الجسيمات استخدام خوارزمية عادةً للتحكم في استجابات النظام على مدى فترة زمنية والقضاء على اإلجراءات غير الضرورية وغير الفعالة وفقًا لألهداف المحددة. تم pso إلدارة المعلمات غير الفعالة داخلmpcوتعزيز استقرار العربة، . كشفت النتائج أن النهج المقترح نجح بشكل كبير وفعال في تقصير وقت االستجابة ، مع األداء العام للنظام إلى تحسين ضبط وقت االستجابة، وبالتالي زيادة كفاءة psoوخفض خطأ االستقرار إلى الصفر تقريبًا. باإلضافة إلى ذلك، أدى دمج ذات األهداف التشغيلية العالية. sbwن كفاءة أنظمة النظام واستجابته. دعمت نتائج الدراسة االقتراح المستند على أن استراتيجية التحكم يمكن أن تحس mailto:alimary76@kecbu.uobaghdad.edu.iq improving the performance of steering by wire using a model predictive controller enhanced with particle swarm optimisation taher sachit taher1, ali hussien mary2*, furat ibrahim hussein3, mohammed ghufran khidhir abboosh4 and muhammad umar fareed5 1,2,3 department of mechatronics engineering, al-khwarizmi college of engineering, university of baghdad, baghdad, iraq 4 department of data science and visualization, university of debrecen, hungary 5 wakefield college, wakefield, england *corresponding author’s email: alimary76@kecbu.uobaghdad.edu.iq https://doi.org/10.22153/kej.2025.01.002 abstract the challenges of steering-by-wire (sbw) systems in vehicles are due to the absence of a direct mechanical link between the steering wheel and the wheels on the road. this limitation imposes the necessity of employing sophisticated control systems to ... keywords: steering by wire; vehicle; model predictive controller; particle swarm optimisation; controller. 1. introduction steering-by-wire (sbw) systems are a promising steering system technology in the field of automotive and transportation industry. such systems found their way largely into automatic guided vehicle (agv) systems, fork lifters and many material handling... early sbw systems used classic proportional integral derivative (pid) controllers, which provide acceptable performance for numerous linear systems. when they are integrated with nonlinearities and time delays or applied in changing operating conditio... fuzzy logic controllers are more suitable for complex and nonlinear systems because of their ability to tolerate instability and loss choices. mitra and kumar [4] improved the flexibility and robustness of fuzzy logic controllers in sbw systems, espec... flexible control strategies are created as a response to the shortcomings of traditional control procedures. adaptive control frameworks robustly change their parameters to adapt to modifications in dynamic systems [6]. the use of adaptive control in... the most prominent advanced control technology used to improve the performance of transmission lines is model predictive control (mpc). it represents a control strategy that can deal with a wide range of constraints and achieve the optimal performance... ates et al. [15] tested the usage of mpc in thermal control structures, which showed high adaptability to surprising environmental adjustments, improving gadget stability and reducing energy intake. similarly, ye et al. [16] showed that mpc can enhanc... particle swarm optimisation (pso) is a popular algorithm specifically designed for the social behaviour of birds and fish. it enhances problem solving by allowing proposed solutions, known as particles, to move in the search space in line with simple ... kumar and sharma [20] tried optimising the mpc parameters using pso, thereby improving overall implementation at scale and reaching faster response states and better tuning in active situations. based on these effects, this consideration suggests comb... the effectiveness of mixing mpc and pso has been explored in many research. huang et al. [22] conducted a comparative assessment of assembled optimisation calculations comprising pso in tuning mpc parameters for chemical system organisation, thus dete... the present study aims to develop and evaluate a mathematical model concentrating on applying mpc-pso in sbw systems. the objective is to expect and control system conduct, using pso to optimise mpc management parameters and comparing the performance ... 2. modelling of sbw systems the hardware of sbw systems has three fundamental subsystems, each containing many sensors or actuators, as shown in figure 1. the assembly of the steering wheel, the front wheel subsystem and some additional mechanical hardware. the guidance wheel in... fig. 1. steering-by-wire system [2] 2.1 modelling of the steering wheel ,ӫ-𝑠.= 1/,𝐽-𝑠.(,𝑇-𝑑𝑟𝑖𝑣𝑒𝑟.−,𝑇-𝑓𝑟𝑖𝑐𝑡𝑖𝑜𝑛.−,𝑏-𝑠𝑐.∗,,ө.-𝑠.−,𝑘-𝑠.∗,ө-𝑠.+,𝑏-𝑠𝑐.∗,,ө.-,𝑚1..+,𝑘-𝑠.∗,ө-,𝑚1..) , … (1) ,ӫ-𝑠.= 1/,𝐽-𝑠.(,𝑇-𝑑𝑟𝑖𝑣𝑒𝑟.−,𝑇-𝑓𝑟𝑖𝑐𝑡𝑖𝑜𝑛.−,𝑏-𝑠𝑐.∗,,ө.-𝑠.−,𝑘-𝑠.∗,ө-𝑠.+,𝑏-𝑠𝑐.∗,,ө.-,𝑚1..+,𝑘-𝑠.∗,ө-,𝑚1..) , …(2) ,𝑑,𝑖-1.-,𝑑𝑡..=1/,𝐿-1.(−,𝑅-1.∗,𝑖-1.−,𝐾-𝑏1.∗,,ө.-𝑚1.+,𝑉-𝑠1.) , …(3) fig. 2. steering wheel subsystem diagram [25] torque of steering motor [26] ,𝑇-,𝑚1..=,𝐾-𝑡.∗,𝑖-1.. … (4) accordingly, the state space representation of the steering wheel system can be expressed as follows: ,𝑋.,𝑡.=,𝐴-,𝑠 ..𝑋,𝑡.+,𝐵-,𝑠..𝑈,𝑡., … (5) output 𝑦,𝑡.=,𝐶-,𝑠..𝑋,𝑡.+,𝐷-,𝑠.. 𝑈(𝑡), … (6) state 𝑋,𝑡.=,,,,ө-𝑠. ,,ө.-𝑠. ,ө-𝑚1. ,,ө.-𝑚1. ,𝑖-1. ..-𝑇.. … (7) the inputs include the driver torque (,𝑇-,𝑑𝑟𝑖𝑣𝑒𝑟..), friction torque (,𝑇-,𝑓𝑟𝑖𝑐𝑡𝑖𝑜𝑛..) and motor voltage (,𝑉-,𝑠1..): 𝑈,𝑡.=,[,𝑇-𝑑𝑟𝑖𝑣𝑒𝑟 . ,𝑇-,𝑓𝑟𝑖𝑐𝑡𝑖𝑜𝑛.. ,𝑉-𝑠1. ]-𝑇., … (8) ,𝐴-𝑠.=,,1-0-0-0-0-,−,𝐾𝑠-𝐽𝑠..-,−,𝑏𝑠𝑐-𝐽𝑠..-,,𝐾𝑠-𝐽𝑠..-,,𝑏𝑠𝑐-𝐽𝑠..-0-0-0-0-1-0-,,𝐾𝑠-𝐽𝑚1..-,−,𝑏𝑠𝑐-𝐽𝑚1..-,−,𝐾𝑠-𝐽𝑚1..-,−,,𝑏𝑚1+𝑏𝑠𝑐.-𝐽𝑚1..-0-0-0-0-,,−𝐾𝑏1-,𝐿1...-,,−𝑅1-,𝐿1....., …(9) ,𝐵-𝑠.=,,0-0-,,,𝑇𝑑𝑟𝑖𝑣𝑒𝑟−𝑇𝑓𝑟𝑖𝑐𝑡𝑖𝑜𝑛.-𝐽𝑠 ..-0-0-0-0-0-0-,,1-,𝐿1..... …(10) the angle and current of the steering motor are the outputs of the system. ,𝐶-𝑠.=,,0-0-1-0-0 -0-0 -0 -0 1.. … (11) ,𝐷-,𝑠..=0 where ,ө-,𝑠.. (degree) is the angular displacement of the steering wheel, ,ө-,𝑚1.. (degree) is the angular displacement of the front wheel motor, ,𝑖-1.(a) is current of steering motor, ks (n.m/rad) is lumped torque stiffness, bsc (n.ms/rad)... as shown in figure 3, the yaw angle (,𝛾-,𝑟𝑎𝑐𝑘..), front wheel angle (,𝛿-,𝑓..) and front motor angle (,ө-,𝑚2..) are the key variables in representing the front wheel subsystem. the force of the rack and the angle of the front tire can... ,,𝛾.-𝑟𝑎𝑐𝑘.= −,𝑏𝑟-𝑚𝑟. ,𝛾-,𝑟𝑎𝑐𝑘..−,,ө-𝑚2.-,,𝐶-𝑚2.∗,𝑔-,𝑚.. ..− ,,𝑔-𝑟.-,𝑐-𝑡..,𝑣-𝑡. … (12) ,,𝛿.-𝑓.= −,,𝐵-𝑡.-,,𝐽-𝑡...,𝛿-𝑓.+,,𝑣-𝑡.-,,,𝑐-𝑡.... … (13) fig. 3. the front wheel subsystem diagram [25]. the current, torque, angular displacement of the front motor and velocity of the tire rod are stated as [27]: ,𝑑,𝑖-2.-𝑑𝑡.=1/,𝐿-2.(−,𝑅-2.∗,𝑖-2.)−,,𝐾-𝑏2.-,𝐽-,𝑚2...∗,t-𝑚2.+,𝑉-𝑠2. … (14) ,,𝑇.-𝑚2.= ,,𝑘-𝑏2.-,,𝐿-2...∗,𝑖-2.−,,𝑏-𝑚2.-,,𝐽-,𝑚2....∗,t-𝑚2.−,,ө-𝑚2.-,𝐶-,𝑚2... … (15) ,,ө.-𝑚2.= ,,𝑇-𝑚2.-,𝐽-,𝑚2...+ ,,𝛾-𝑟𝑎𝑐𝑘.-,𝑚-𝑟.∗,𝑔-𝑚.. … (16) ,,𝑣.-𝑡.= ,,𝛾-𝑟𝑎𝑐𝑘.-,𝑚-𝑟.∗,𝑔-,𝑟...−,,𝑣-𝑡.-,𝑗-,𝑡... … (17) the state space model of the front wheel subsystem is ,𝑋.,𝑡.=,𝐴-,𝑓..𝑋,𝑡.+,𝐵-𝑓.𝑈(𝑡) . … (18) the output angle of the steering motor represents the input to the front wheel subsystem: 𝑈,𝑡.=,[ ,ө-,𝑚1.. ]-𝑇.. the output and state of the front wheel subsystem: 𝑦,𝑡.=,𝐶-𝑓.𝑋,𝑡.+,𝐷-,𝑓.. 𝑈(𝑡) … (19) 𝑋,𝑡.=,[,𝑖-2. ,𝑇-𝑚2. ,𝛾-𝑟𝑎𝑐𝑘. ,𝛿-,𝑓.. ,ө-𝑚2. ,𝑣-,𝑡..]-𝑇. … (20) the outputs of the front wheel system are the front motor angle and the wheel angle: ,𝐴-𝑓.=,,,−,𝑅2-𝐿2..-,−,𝐾𝑏2-𝐽𝑚2..-0-0-0-0-,,𝐾𝑏2-𝐿2..-,−,𝑏𝑚2-𝐽𝑚2..-0-0-,−,1-𝐶𝑚2..-0-0-0-0-,−,𝐵𝑡-𝐽𝑡..-0-,,1-𝐶𝑡..-0-,,1-𝐽𝑚2..-,−,1-𝑔𝑚+𝑚𝑟..-0-0-0-0-0-,,1-,𝑔𝑟+𝑚𝑟...-,−,1-𝐽𝑡..-0-0.. , …(21) ,𝐵-𝑓.=,,1-0-0-0-0.., … (22) ,𝐶-𝑓.=,,0-0-0-1-0-0-0-0-0-0-1-0.., … (23) ,𝐷-,𝑓..=0, where br (n.m/rad) is the resistance rack, mr (kg) is the mass rack, cm2 (n.m/s) is the front motor shaft compliance, gm (m) is the column pinion radius, gr (m) is the length ratio steering arm, ct (rad/n.m) is the compliance of the tire rod, bt (n.m.... 3. controller design one effective and adaptable control method that is frequently applied to dynamic systems is mpc. it works especially well in situations such as sbw systems where managing restrictions is essential. using a mathematical model, mpc forecasts a system’s ... to minimise a cost function, which usually represents the departure from the intended system trajectory whilst considering system restrictions, mpc solves an optimisation problem at each time step. this control strategy is based on the representation of system dynamics using a state space model. the basic model utilised in mpc, which is typically described in the state space form, must be presented before going into the specific mathematical formulation. the system dynamics in mpc consists of system matrices a,b,and c[7][8][11][15]: ,𝑍-𝑘+v|𝑘.=𝐶,𝐴-𝑣.,𝑋-𝑘.+,c,𝐴-𝑣−1. 𝐶,𝐴-𝑣−2.𝐵 …𝐶𝐴𝐵 𝐶𝐵. ,,,,𝑈-𝑘|𝑘.-,𝑈-𝑘+1|𝑘.-,𝑈-𝑘+2|𝑘.-.-.-.-,𝑈-𝑘+𝑣−2|𝑘.-,𝑈-𝑘+𝑣−1|𝑘.... , … (24) [16] where ,𝑍-𝑘. ∈,ℝ-𝑟. is the output that needs to be controlled, and 𝑣 is the control horizon. the predictive for the final step (k+f) can be obtained by ,𝑍-𝑘+f|𝑘.=𝐶,𝐴-𝑓.,𝑋-𝑘.+,c,𝐴-𝑓−1. 𝐶,𝐴-𝑓−2.𝐵…𝐶,𝐴-𝑓−𝑣+1.𝐵 𝐶,,𝐴.-𝑓,𝑣.𝐵.,,,𝑈-𝑘|𝑘.-,𝑈-𝑘+1|𝑘.-,𝑈-𝑘+2|𝑘.-.-.-.-,𝑈-𝑘+𝑣−2|𝑘.-,𝑈-,𝑘+𝑣−1|𝑘...., … (25)[16] 𝑍=𝑂,𝑋-,𝑘..+𝑀𝑈 , … (26)[16][19] 𝑍=,,,𝑍-𝑘+1|𝑘.-,𝑍-𝑘+2|𝑘.-,𝑍-𝑘+3|𝑘.-.-.-,𝑍-𝑘+𝑣|𝑘.-,𝑍-𝑘+𝑣+1|𝑘.-.-.-,𝑍-,𝑘+𝑓|𝑘.... , 𝑈=,,,𝑈-𝑘|𝑘.-,𝑈-𝑘+1|𝑘.-,𝑈-𝑘+2|𝑘.-.-.-.-,𝑈-𝑘+𝑣−2|𝑘.-,𝑈-𝑘+𝑣−1|𝑘... , 𝑂=,,𝐶𝐴-𝐶,𝐴-2.-𝐶,𝐴-3.-.-.-𝐶,𝐴-𝑣.-𝐶,𝐴-𝑣+1.-.-.-𝐶... … (27)[20] m= ,,𝐶𝐵-0-0-0-…-0-𝐶𝐴𝐵-𝐶𝐵-0-0-…-0-𝐶,𝐴-2.𝐵-𝐶𝐴𝐵-𝐶𝐵-0-…-0-,.-.-..-,.-.-..-,.-.-..-…-…-,.-.-..-𝐶,𝐴-𝑣−1.𝐵-𝐶,𝐴-𝑣−2.𝐵-𝐶,𝐴-𝑣−3.𝐵-…-𝐶𝐴𝐵-𝐶𝐵-𝐶,𝐴-𝑣.𝐵-𝐶,𝐴-𝑣−1.𝐵-𝐶,𝐴-𝑣−2.𝐵-…-𝐶,𝐴-2.𝐵-𝐶,,𝐴.-1,𝑣.𝐵-,.-.-..-,.-.-..-,.-.-... … (28)[22] where m is a state prediction matrix. let these desired outputs be denoted by ,,𝑍-𝑑.-𝑘+1., ,,𝑍-𝑑.-𝑘+2.,,,𝑍-𝑑.-𝑘+3.,………., ,,𝑍-𝑑.-,𝑘+𝑓.. , … (29)[23] ,𝑍-𝑑.=,,,,𝑍-𝑑.-𝑘+1.-,,𝑍-𝑑.-𝑘+2.-,,𝑍-𝑑.-𝑘+3.-.-.-.-.-,,𝑍-𝑑.-,𝑘+f.... . … (30)[28] the cost function can be expressed as [29] ,𝑚𝑖𝑛-,𝑈..,,,,𝑍-𝑑.−𝑍..-2.= ,𝑚𝑖𝑛-𝑈. ,,,𝑍-𝑑.−𝑍.-𝑇.(,𝑍-𝑑.−𝑍). … (31) by substituting ,𝑍-𝑑.and 𝑍, the final form of the cost function that will penalise the inputs becomes clear as shown in the following equation: ,𝐽-,𝑈..= ,𝑈-𝑇.,𝑊-3.𝑈, … (32) where ju is a cost function for control input, u is an input vector control, and w3 is a final weighting matrix. ,𝑊-,3..=,,𝑊-𝑇.-1.,𝑊-2.,𝑊-,1.. … (33)[30][7] ,𝑊-2.=,,,𝑄-0.-0-0-..-..-0-0-,𝑄-1.-0-..-..-0-0-..-.-..-..-0-.-..-..-.-..-.-.-..-..-..-.-.-0-0-0-..-..-,𝑄-,𝑣−1.... … (34) matrix dimensions are ,𝑊-,2..=[𝑚∗𝑛,𝑚∗𝑛], where w1, w2, m and n are the state prediction matrix, input weight matrix, number of outputs and number of inputs, respectively. the cost function that corresponds to the tracking error is ,𝐽-,𝑧..= ,,𝑆−𝑀𝑈.-𝑇.,𝑊-4.( 𝑆−𝑀𝑈), … (35)[7] where ( 𝑆=,𝑍-𝑑.−𝑂,𝑋-,𝑘..). the cost function penalises the difference between the desired and controlled trajectory as shown in the following equation [7]: ,𝑚𝑖𝑛-𝑈. ,𝐽-,𝑧..+,𝐽-,𝑈.. . … (36) by partial derivative of the cost function for u, ,𝜕𝐽-,𝜕𝑈..= −2,𝑀-𝑇.,𝑊-4.+2,𝑀-𝑇.,𝑊-4.𝑀𝑈+2,𝑊-3.𝑈 . … (37) to find the minimum of the cost function for u, ,𝜕𝐽-,𝜕𝑈..=0. … (38) ,𝜕𝐽-,𝜕𝑈..= −2,𝑀-𝑇.,𝑊-4.+2,𝑀-𝑇.,𝑊-4.𝑀𝑈+2,𝑊-3.𝑈=0. … (39) from equation (39), the solution of the mpc is ,𝑈.=(,𝑀-𝑇.,𝑊-,4..𝑀+,𝑊-3.),𝑀-𝑇.,𝑊-,4..𝑆. … (40) the initial parameters of the mpc were selected on the basis of theoretical practices that fit the system parameters and through manual tuning in the early simulation stages. however, pso was later applied to tune these parameters automatically to imp... 3.2 pso algorithm the pso algorithm can be utilised to find optimal values in various applications, most notably in pid controllers [31] [32]. however, it is rarely used in the mpc approach. pso calculation is used in finding the optimal values ​​of the weight matrix w... as depicted in figure 4, the pso process iteratively updates the position and velocity of each particle. each particle tracks two key metrics: ,𝑃-,𝑏𝑒𝑠𝑡..: the particle’s best-known position based on its objective function ,𝑔-,𝑏𝑒𝑠𝑡..: the best position discovered by the entire swarm these metrics are critical in guiding particles towards the global optimum. the inertia weight, also shown in figure 4, controls the balance between exploration and exploitation. the inertia weight is ∅= ,∅-𝑚𝑎𝑥.−,,,∅-𝑚𝑎𝑥.−,∅-𝑚𝑖𝑛.-,𝑇-,𝑚𝑎𝑥..... … (41)[35] let x and v be the position and velocity respectively. the equations for updating the velocity and position are as follows: ,𝑣-,𝑖,𝑙..,𝑡.=∅,𝑣-,𝑖,𝑙..,𝑡−1.+ ,𝑐-1.,𝑟-1.,,𝑃-𝑏𝑒𝑠𝑡. −,𝑥-,𝑖,𝑙..,𝑡−1..+ ,𝑐-2.,𝑟-2.,,𝑔-𝑏𝑒𝑠𝑡.−,𝑥-,𝑖,𝑙..,𝑡−1.., … (42)[36] ,𝑥-(𝑖,𝑙).(𝑡)=,𝑥-(𝑖,𝑙).,𝑡−1.+,𝑣-(𝑖,𝑙).(𝑡), … (43)[36] where ,𝑐-1., ,𝑐-2, .𝑖, 𝑙 are the individual and social cognitive, number of particles and number of variations, respectively, and ,𝑟-1., ,𝑟-,2.. are uniformly distributed randomly. ,𝑄-,0.., …, ,𝑄-𝑣−1. are values of the weight matrix, up... ,𝑄-0. = ,𝑥-(𝑖,1). , ,𝑄-𝑣−1.= ,𝑥-,,𝑖,𝑚∗𝑛... fig. 4. flowchart of pso table 1, parameters of pso 4. results and discussion the simulation was conducted on a windows 10 pc, offering a reliable environment suitable for operating the python 2022 programming environment. the values ​​mentioned in table 3[27] were adopted as a basis for simulating the system in the absence of the pso algorithm for the steering wheel system. the initial values of qo and q1,v−1 equal to 10−10 and 10−9 respectively were chosen on the basi... 4.1.1 cases of step and square response figure 5 graphs the step response for the angle of steering motor qm1. the use of pso with mpc has remarkably improved the angle in terms of the settling time, which decreased from 2.096 seconds to 0.268 seconds, and overshoot decreased from 6.524% to... fig. 5. step response for the angle of a steering motor ,ө-,𝒎𝟏.. fig. 6. square response for the angle of a steering motor, ө-,𝒎𝟏.. 4.2 front wheel simulation in the front wheel system, the values for the weight matrix qo and q1,v−1 equal to 10−6 and 10−3 respectively were employed, with constraints between a maximum of 10−20, 10−10 and a minimum of 10−25, 10−15. the obtained result of pso for the weight va... fig. 8. step response for the angle of the front tire, 𝜹-𝒇. fig. 9. square response for the angle of the front wheel motor ,ө-,,𝒎𝟐... fig. 10. square response for the angle of the front tire ,𝜹-𝒇.. 5. conclusion 6. future development proposal one suitable proposal for future development of the research topic is to integrate adaptive or machine learning algorithms with pso to adjust parameters in real time, which helps enhance control over disturbances and changing conditions and achieve ... table 2, performance indexes table 3, steering-by-wire system parameters references [1] s. a. mortazavizadeh, a. ghaderi, m. ebrahimi, and m. hajian, “recent developments in the vehicle steer-by-wire system,” ieee trans. transp. electrif., vol. 6, no. 3, pp. 1226–1235, 2020. 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[38] m. a. mohamed, a. m. eltamaly, and a. i. alolah, “pso-based smart grid application for sizing and optimization of hybrid renewable energy systems,” plos one, vol. 11, no. 8, pp. 1–22, 2016, doi: 10.1371/journal.pone.0159702. تحسين أداء التوجيه عن طريق الأسلاك باستخدام وحدة التحكم التنبؤية للنموذج mpc المعززة بخوارزمية تحسين سرب الجسيمات pso طاهر ساجت طاهر1 ، علي حسين مري*2 ، فرات ابراهيم حسين3 ، محمد غفران خضر عبوش4 ، محمد عمر فريد5 3،2،1 قسم هندسة الميكاترونيكس، كلية الهندسة الخوارزمي، جامعة بغداد، بغداد ، العراق 4 قسم علوم البيانات والتصور، جامعة ديبريسين، المجر 5 كلية ويكفيلد، ويكفيلد، انجلترا *البريد الالكتروني: alimary76@kecbu.uobaghdad.edu.iq المستخلص إن التحديات التي تواجه أنظمة التوجيه بالأسلاك (sbw) في المركبات ذات التوجيه ترجع إلى غياب الرابط الميكانيكي المباشر بين عجلة القيادة والعجلات على الطريق. هذا الامر يفرض ضرورة استخدام أنظمة تحكم متطورة لتحقيق أعلى درجات الدقة والاستقرار أثناء التوجيه.... this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 19, no. 4, december, (2023) p. p. 2941 working memory classification enhancement of eeg activity in dementia: a comparative study noor kamal al-qazzaz* sawal hamid bin mohd ali ** siti anom ahmad *** *department of biomedical engineering/ al-khwarizmi college of engineering/ university of baghdad/ baghdad / iraq ** department of electrical, electronic & systems engineering, faculty of engineering & built environment, universiti kebangsaan malaysia/ ukm bangi/ selangor 43600/ malaysia centre of advanced electronic and communication engineering, department of electrical/ electronic and systems engineering/ universiti kebangsaan malaysia/ selangor 43600/ malaysia ***department of electrical and electronic engineering, faculty of engineering, universiti putra malaysia, upm serdang/ selangor 43400/ malaysia malaysian research institute on ageing (myageing™)/ universiti putra malaysia/ serdang/ selangor 43400/ malaysia corresponding author *email: noorbme@kecbu.uobaghdad.edu.iq **email: sawal@ukm.edu.my ***email: sanom@upm.edu.my (received 2 january 2023; accepted 20 september 2023) https://doi.org/10.22153/kej.2023.09.002 abstract the purpose of the current investigation is to distinguish between working memory (𝑊𝑀) in five patients with vascular dementia (𝑉𝐷), fifteen post-stroke patients with mild cognitive impairment (𝑆𝑀𝐶𝐼), and fifteen healthy control individuals (𝐻𝐶) based on background electroencephalography (eeg) activity. the elimination of eeg artifacts using wavelet (wt) pre-processing denoising is demonstrated in this study. in the current study, spectral entropy (𝑆𝑝𝑒𝑐𝐸𝑛), permutation entropy (𝑃𝑒𝑟𝐸𝑛), and approximation entropy (𝐴𝑝𝐸𝑛) were all explored. to improve the 𝑊𝑀 classification using the k-nearest neighbors (𝑘nn) classifier scheme, a comparative study of using fuzzy neighbourhood preserving analysis with 𝑄𝑅-decomposition (𝐹𝑁𝑃𝐴𝑄𝑅) as a dimensionality reduction technique and the improved binary gravitation search (𝐼𝐵𝐺𝑆𝐴) optimization algorithm as a channel selection method has been conducted. the 𝑘nn classification accuracy was increased from 86.67% to 88.09% and 90.52% using the 𝐹𝑁𝑃𝐴𝑄𝑅 dimensionality reduction technique and the 𝐼𝐵𝐺𝑆𝐴 channel selection algorithm, respectively. according to the findings, 𝐼𝐵𝐺𝑆𝐴 reliably enhances 𝑊𝑀 discrimination of 𝐻𝐶 , 𝑆𝑀𝐶𝐼 , and 𝑉𝐷 participants. therefore, wt, entropy features, ibgsa and 𝑘nn classifiers provide a valid dementia index for looking at eeg background activity in patients with 𝑉𝐷 and 𝑆𝑀𝐶𝐼. keywords: dementia, wavelet, entropy, dimensionality reduction, channels selection, features, classification. 1. introduction stroke is broadly categorized by its type and severity and the brain region affected. dementia can be brought on after a stroke, and its severity relies on how quickly the condition is identified and treated [1]. following a stroke, working memory (𝑊𝑀) impairment is common. within the first year of stroke diagnosis, vascular dementia (𝑉𝐷) may develop in 30% of stroke patients. the prevalence of 𝑉𝐷 doubles every 5-10 years after the age of 65 in the elderly population. clinically speaking, mild cognitive impairment ( 𝑀𝐶𝐼 ), in particular in attention, memory, language and orientation is a transition stage of cognitive decline [2]. at the time of diagnosis, attention, executive mailto:noorbme@kecbu.uobaghdad.edu.iq mailto:aseel.m.ali@nahrainuniv.edu.iq mailto:sanom@upm.edu.my https://doi.org/10.22153/kej.2023.09.002 https://doi.org/10.22153/kej.2023.09.002 noor k. al-qazzaz al-khwarizmi engineering journal, vol. 19, no. 4, p.p. 2941(2023) 30 functioning, and memory show the greatest impact of a stroke [3]. patients who had suffered from cognitive impairment as a result of a stroke were the first to be introduced to the vascular cognitive impairment (vci) spectrum, which spans the range from mild cognitive impairment (𝑀𝐶𝐼) to advanced dementia. however, the phrase "cognitive impairment no dementia" (cind) is used to refer to the period of time following dementia during which the brain is in danger [4]. people who have 𝑀𝐶𝐼 , have a more severe decline in cognitive performance when age and education level are included, yet this decline is not as obvious in day-to-day tasks. although some people with 𝑀𝐶𝐼 will eventually develop dementia, others will remain in this 𝑀𝐶𝐼 stage for a significant amount of time before progressing to dementia. because of this, 𝑀𝐶𝐼 is a disorder that can present very differently in different patients. in any case, research has been shown that patients diagnosed with 𝑀𝐶𝐼 have a substantial risk of developing dementia by the third month following the onset of dementia symptoms. this risk was observed to increase significantly with time. the symptoms most commonly associated with 𝑀𝐶𝐼 are those related to attention and executive function in 𝑊𝑀. daily functioning is unaffected by mild cognitive impairment. a decline in long-term memory, particularly episodic memory, is related to dementia, which is the next step following mild cognitive impairment. mild cognitive impairment is the stage before dementia. 10% of patients will acquire post-stroke dementia (psd) or severe dementia in the months following the commencement of an ischemic stroke (30% with recurrent ischemic stroke). this can happen as early as three months after the stroke [3]. electroencephalography (eeg) has been extensively employed in recent years to investigate the cortical abnormalities linked to dementia and cognitive decline [5]. as a result, eeg signal analysis may reveal information on cognitive decline and dementia. clinical eeg has a frequency range of 1 to 100 hz and an amplitude of about 10-100 millivolts [6]. the main differences between healthy people and those with a problem with working memory (𝑊𝑀) can be summed up as follows: dementia causes a slowing of eeg signals due to a power shift to lower frequencies and decreased corticalsubcortical communication for patients with 𝑉𝐷 and 𝑆𝑀𝐶𝐼 . also, the reduction in signal complexity caused by dementia and other neurodegenerative diseases. understanding the differences between how healthy people and people with 𝑊𝑀 problems show eeg signals can help make clinical signs and better ways to diagnose neurological illnesses [5]. however, the eeg is impacted by extracranial sources known as artifacts, which can imitate the abnormal activity of the brain and hence impair the analysis. such artifacts have been seen in eeg recordings and wrongly attributed to neurological disorders. clinical studies involving eeg signals necessitate the creation of automatic algorithms to eliminate artifacts. several methods have been proposed for artifact removal in the literature [7], including regression-based analysis, wavelet transform (wt), independent component analysis (ica), blind source separation (bss), and epoch rejection. in another example of an automated hybrid artifact removal method, al-qazzaz et al. estimated ics first, then used dwt to detect components as artifacts that had been marked and denoised. to produce an eeg devoid of artifacts, we correct the ics and then reconstruct them using inv-ica. the benefits of the proposed method were seen by the authors, who found that it improved discriminating between dementia and healthy groups [5, 8]. numerous studies have been conducted over the past few years to examine the impact of 𝑀𝐶𝐼 and ad on eeg signals and how they change over time. using resting-state eeg recordings, yin et al. have devised a scheme based on integrated spectral and temporal analysis for the identification of 𝑀𝐶𝐼 . stationary wavelet transform (swt) and descriptive statistical analysis with support vector machine (svm) classifiers were used to establish a three-dimensional discrete feature space. a machine learning-based methodology has been presented by kashefpoor et al. to distinguish between 𝑀𝐶𝐼 and normal cases utilizing basic spectral frequency band eeg data [9]. eight eeg biomarkers, including power spectral density, skewness, kurtosis, spectral skewness, spectral kurtosis, spectral crest factor, spectral entropy, and fractal dimension, have been studied by sharma et al. for the diagnosis of individuals with 𝑀𝐶𝐼 [10]. using the 𝑘-nearest neighbors (𝑘nn) technique, durongbhan et al. developed a supervised classification framework for eeg signals to distinguish between healthy controls and ad participants [11]. previous research has largely used a 2-way classification ( 𝐴𝐷 vs. 𝐻𝐶 , 𝑆𝑀𝐶𝐼 vs. 𝐻𝐶 ) however some studies have reported using a 3-way classification. other researchers have looked into the possibility of using power spectrum analysis for the early diagnosis of ad and 𝑆𝑀𝐶𝐼 [5]. in [12] , neuro-markers based on complexity are calculated from ad patients and 𝐻𝐶 participants. these noor k. al-qazzaz al-khwarizmi engineering journal, vol. 19, no. 4, p.p. 2941(2023) 31 complexity measures include fractal dimension and lempel-ziv complexity. a variety of entropies, such as spectral entropy (𝑆𝑝𝑒𝑐𝐸𝑛 ), permutation entropy ( 𝑃𝑒𝑟𝐸𝑛 ), tsallis entropy ( 𝑇𝑠𝐸𝑛 ), approximation entropy ( 𝐴𝑝𝐸𝑛 ), and sample entropy (𝑆𝑎𝑚𝑝𝐸𝑛 ), could be computed for this demand in order to examine the eeg markers that may aid in dementia early detection [13]. a three-way categorization methodology was used in one study [14]. eyes-open, eyes-closed with a counting task, and eyes-closed conditions were used to compute spectral and complexity features from 𝐻𝐶 , 𝑆𝑀𝐶𝐼 , and ad participants, respectively. time-frequency domain parameters (relative power band, median frequency) and entropy-based neuro-markers (spectral entropy, sample entropy, auto-mutual information) have been merged by ruiz-gomez et al. [15]. eyes-open and eyes-closed eeg recordings were obtained from individuals with 𝐴𝐷 , 𝑀𝐶𝐼 , and 𝐻𝐶 [16]. classification was carried out using linear discriminant analysis (lda), quadratic discriminant analysis (qda), and multi-layer perceptron (mlp). toural et al. have classified patients into three groups using wavelet entropy, relative beta, and theta power [17]. in the preclassification phase, a svm is employed for binary assessment, and in the classification phase, a neural network is implemented for the voting mechanism. the power spectrum density of eeg sub-bands and interhemispheric coherence were determined by oltu et al. using data from 𝐴𝐷 , 𝑀𝐶𝐼 , and 𝐻𝐶 . each eeg sub-band's variance and amplitude sum, as well as the coherence amplitude sum, are included in the feature vectors [18]. the use of eeg for the detection and classification of dementia-related brain activity patterns has shown encouraging results. in spite of this, additional study is required in two areas: dimensionality reduction and channel selection. first of all, dimensionality reduction strategies try to minimize the loss of information by simplifying the number of features or variables in eeg data. next-generation classification algorithms can be made more manageable in terms of both complexity and computing overhead if the dimensionality of the data is reduced. the best dimensionality reduction strategies to improve eeg categorization in dementia are not yet fully understood. despite their success elsewhere, techniques for dimensionality reduction were applied to increase the classification accuracy. there are many techniques that can be applied, including the well-known principal component analysis (pca) technique for dimensionality reduction. the pca approach is frequently used to prevent redundancy in high-dimensional data [19]. additionally, channel selection is a type of feature selection that may be applied to the removal of irrelevant or noisy channels and the selection of channels with related features [20]. the most efficient eeg channels have been determined using the sparse common spatial pattern (scsp) algorithm, the mutual information technique [21, 22], the recursive channel elimination (rce) approach [23], and the differential evolution – based channel selection algorithm (defs_ch) [20, 24]. although the strategy of channel selection can offer the benefits of eliminating unimportant channels or choosing a small number of significant eeg features to enhance classification performance. second, channel selection includes picking the eeg channels that add the most value to the categorization process. this method can enhance classification precision, however, the best way to pick channels for eeg classification purposes in dementia is not yet certain. channel selection can be based on a variety of parameters, including statistics, spectral analysis, and geographical patterns; nevertheless, their efficacy and robustness must be assessed in the context of dementia [25]. most of the approaches in the literature have a complicated structure and take a long time since they do not employ a data-efficient reduction technique, which is necessary for fast and accurate analysis. effective dimensionality reduction approaches and optimal channel selection procedures are the last pieces of the puzzle when it comes to improving eeg classification for dementia. closing these knowledge gaps will aid in the creation of more precise and time-saving eegbased categorization systems for the diagnosis and monitoring of dementia. to improve eeg categorization for dementia, more study is needed to analyze and compare different ways and determine the most suitable techniques. based on background electroencephalography (eeg) activity, the goal of the current investigation is to differentiate between working memory (𝑊𝑀) in five patients with vascular dementia ( 𝑉𝐷 ), fifteen post-stroke patients with mild cognitive impairment (𝑆𝑀𝐶𝐼 ), and fifteen healthy control individuals (𝐻𝐶). in the current study, as spectral entropy (𝑆𝑝𝑒𝑐𝐸𝑛), permutation entropy (𝑃𝑒𝑟𝐸𝑛) and approximation entropy ( 𝐴𝑝𝐸𝑛 ), were the features that were selected to investigate the 𝑊𝑀 and classify their tasks using the k-nearest neighbours (𝑘nn) classifier scheme. therefore, a comparative study of using the fuzzy neighborhood noor k. al-qazzaz al-khwarizmi engineering journal, vol. 19, no. 4, p.p. 2941(2023) 32 preserving analysis with 𝑄𝑅 -decomposition ( 𝐹𝑁𝑃𝐴𝑄𝑅 ) as a dimensionality reduction technique and the improved binary gravitation search ( 𝐼𝐵𝐺𝑆𝐴 ) optimization algorithm as a channel selection method has been conducted. the 𝐹𝑁𝑃𝐴𝑄𝑅 was used in this investigation as a dimensionality reduction method to maximize the distance between the centers of various classes while minimizing the distance between samples that belong to the same class [26, 27]. additionally, the most efficient channels that increase classification accuracy have been found using the 𝐼𝐵𝐺𝑆𝐴 algorithm [25]. additionally, the suitability of 𝑆𝑝𝑒𝑐𝐸𝑛 , 𝐴𝑝𝐸𝑛 , and 𝑃𝑒𝑟𝐸𝑛 characteristics for the early identification of 𝑉𝐷 was examined. 𝑘nn classifier has also been used to identify patients with post-stroke 𝑊𝑀 dysfunction. 2. materials and methods to improve the 𝑊𝑀 classification of dementia patients, the eeg signals would undergo various signal processing phases, as shown in figure 1. the participants in this eeg study participated in a session of an auditory 𝑊𝑀 task. the nonstationary eeg signals were initially processed using a wavelet (wt) denoising approach during the preprocessing step. after that, we look into and extract the meaningful features, such as non-linear 𝑆𝑝𝑒𝑐𝐸𝑛, 𝐴𝑝𝐸𝑛, and 𝑃𝑒𝑟𝐸𝑛 entropy features, and conduct a comparison of the dimensionality reduction techniques fuzzy neighborhood preserving analysis with qr-decomposition (𝐹𝑁𝑃𝐴𝑄𝑅) and the improved binary gravitation search (ibgsa) optimization algorithm for channel selection. finally, the performance of the classifiers utilized is evaluated, showing that dementia classification techniques can be used to categorize patients' mental disability after stroke. fig. 1. the block diagram of the proposed study. 2.1 participants in the current investigation, 35 patients' eeg datasets were examined. the sample was recruited from the stroke unit and neurology clinic at the pusat perubatan universiti kebangsaan malaysia (ppukm). 15 𝐻𝐶 participants (7 male and 8 female,age 60.06±5.21), 15 𝑆𝑀𝐶𝐼 patients (5 male and 10 female,age 60.26±7.77), and 5 𝑉𝐷 patients (3 male and 2 female,age 64.6±4.8) had their eeg data reviewed. the cognitive evaluations that were administered to the three groups were the mini-mental state examination (mmse) [7] and the montreal cognitive assessment (moca) [8]. 𝐻𝐶 participants' mmse and moca scores were (29.6±0.73,29.06±0.88), but 𝑆𝑀𝐶𝐼 patients' mmse and moca scores were (20.2±5.63 and 16.13±5.97), respectively. lastly, the mmse and moca scores for the 𝑉𝐷 patients were (14.8±1.92 and 14.8±1.92) respectively. the experimental methods utilized throughout the research were approved by ppukm's human ethics committee, and the patients' voluntary and informed consent was secured by acquiring signed consent forms. all patients were diagnosed using computed noor k. al-qazzaz al-khwarizmi engineering journal, vol. 19, no. 4, p.p. 2941(2023) 33 tomography/magnetic resonance imaging (ct/mri) scans, patient medical histories, and clinical and laboratory tests. 2.2 eeg recording nicoletone (v32) was utilized in order to collect the 19 eeg channel datasets. using a single ground electrode and two reference electrodes with 19 channels starting from left, right to the center, these are: fp2, f8, t4, t6, o2, fp1, f7, t3, t5, o1, f4, c4, p3, f3, c3, p3, fz, cz and pz. a referential montage was created, and the channels were constructed according to the 10-20 international framework. the nicolet eeg system was sampled at 256 hz, and the electrode-skin impedance was tested to ensure that it did not exceed10 kilo ohms. this corresponded to a sensitivity of 100 v/cm, whereas the low cut-off frequency and high cut-off frequency were, respectively, 0.5 hz and 70 hz. the eeg was recorded for 60 seconds, with a 0.5-second fixation cue preceding the start of the recording period. the patients were then asked to commit five words to memory for 10 seconds as part of a simple auditory 𝑊𝑀 test involving working memory. following this, eeg recordings were made as each subject attempted to recall the phrase. after the 60-second interval elapsed, the researcher instructed the participants of the sample group to open their eyes and to recall in turn each of the words they had memorized [3]. 2.3 preprocessing stage in this investigation, wt denoising was utilized to eliminate eeg artifacts. since the sampling frequency was 256 hz [28], the symlets mother wt of order 9 'sym9' and 5 decomposition levels were utilized to decompose the acquired eeg information. as in equation 1, the discrete values of 𝑎 and 𝑏 can process the dwt. it can be constructed as 𝑎 set of decomposition functions of the correlation between the signal 𝑓(𝑡) and the shifting and dilating of the mother wavelet function 𝜓(𝑡). in equation 2, location parameter 𝑏 shifts mwt and the frequency scaling parameter 𝑎 dilates or contracts it [29, 30]: 𝐷𝑊𝑇𝑚,𝑛(𝑓) = 𝑎0 −𝑚 2⁄ ∫ 𝑓(𝑡) 𝜓(𝑎0 −𝑚𝑡 − 𝑛𝑏0)𝑑𝑡 . . . (1) 𝑎0 and 𝑏0 values are set to 2 and 1, respectively. 𝜓𝑎,𝑏(𝑡) = 1 √𝑎 𝜓 ( 𝑡 − 𝑏 𝑎 ) , 𝑎𝜖ℝ+, 𝑏𝜖ℝ … (2) 2.4 features extraction stage each eeg dataset had 19 channels with a duration of 60 seconds, so 15360 samples were utilized for this study. entropies have been utilized to identify anomalies in dementia patients' eegs. the eegs of dementia patients have been separated from those of age-matched healthy people using 𝑆𝑝𝑒𝑐𝐸𝑛 [31-33]. after normalizing the power spectral density ( 𝑃𝑆𝐷 ) to a scale from 0 to 1 to obtain normalized psd (psdn), which has the value 1 for ∑ psdn(f) = 1, the 𝑆𝑝𝑒𝑐𝐸𝑛 is computed as in equation 3 [31]. 𝑆𝑝𝑒𝑐𝐸𝑛 = −1 log(𝑁) ∑ 𝑃𝑆𝐷𝑛(𝑓) log[𝑃𝑆𝐷𝑛(𝑓)]64𝐻𝑧 𝑓=0.1𝐻𝑧 … (3) utilizing the algorithm described in [34], 𝐴𝑝𝐸𝑛 is calculated as in equation 4 [35]. 𝐴𝑝𝐸𝑛(𝑚, 𝑟, 𝑁) = ∅𝑚(𝑟) − ∅𝑚+1(𝑟) … (4) where, ∅𝑚 is the natural logarithm for 𝑚 contiguous observation within tolerance width 𝑟 and 𝑁 is the number of points of the eeg time series. for the sake of our analysis, 𝐴𝑝𝐸𝑛 is calculated with a tolerance of r = 0.2 × sd and a run length of m = 2 epochs, where sd is the standard deviation. in the case of 𝑃𝑒𝑟𝐸𝑛, this sort of entropy is widely employed in the context of artefacts and noise , and one of its distinguishing properties [36] is its computational speed. in terms of 𝑃𝑒𝑟𝐸𝑛 's applications, non − stationary and non − linear signals are frequently employed [37]. 𝑃𝑒𝑟𝐸𝑛 has been utilized by researchers to assess the complexity of eeg signals in alzheimer′s disease (ad) patients [38]. the 𝑃𝑒𝑟𝐸𝑛 can also be used to detect aberrant electrical activity in the brain, which cannot be demonstrated by traditional eeg signal detection methods [39]. when all motifs have equal probability, the largest value of 𝑃𝑒𝑟𝐸𝑛 is obtained, which has a value of ln 𝑑!, where 𝑑 = 3, 𝑙 = 1. in contrast, if there is only one 𝑝(𝜋𝑘) different from zero, which illustrates a completely regular signal, the smallest value of 𝑃𝑒𝑟𝐸𝑛 is obtained as much as 0 [36, 40, 41]. for 60 seconds, 𝑁 = 15360 samples, 6 windows of 10 second length (2560 samples) noor k. al-qazzaz al-khwarizmi engineering journal, vol. 19, no. 4, p.p. 2941(2023) 34 were extracted from the original eeg time series for each of 19 channels. in order to estimate the 𝑃𝑒𝑟𝐸𝑛 , assume the time series of 𝑦 = {𝑦1, 𝑦2, … , 𝑦𝑁} of length 𝑁, at each time 𝑡 of 𝑦 a vector including the 𝑑𝑡ℎ subsequence value constructed as: 𝑌𝑡 𝑑,𝑙 = {𝑦𝑡 , 𝑦𝑡+1, … , 𝑦𝑡+(𝑑−2)𝑙 , 𝑦𝑡+(𝑑−1)𝑙} for 𝑡 = 1,2, … , 𝑁 − (𝑑 − 1)𝑙 , where 𝑑 is the embedded dimension, determines how much information is contained in each vector and 𝑙 is the time delay. to calculate the 𝑃𝑒𝑟𝐸𝑛 , the 𝑑 of 𝑦𝑖 are associated with numbers from 1 to 𝑑 and arranged in increasing order as {𝑦𝑡+(𝑗1−1)𝑙, 𝑦𝑡+(𝑗2−1)𝑙 , … , 𝑦𝑡+(𝑗𝑑−1−1)𝑙 , 𝑦𝑡+(𝑗𝑑−1)𝑙} for different samples, there will be 𝑑! potential ordinal patterns, 𝜋 , which are named “motifs” [38]. for each 𝜋𝑡 , 𝑝(𝜋𝑡) demonstrate the relative frequency as follows: 𝑝(𝜋𝑖 𝑑,𝑙) = #{𝑡|𝑡≤𝑁−𝑑,type(𝑌𝑡 𝑑,𝑙)=𝜋𝑖 𝑑,𝑙 } 𝑁−𝑑+1 …(5) where #{ } denotes the cardinality of the set (the number of elements). the 𝑃𝑒𝑟𝐸𝑛 is computed as follows: 𝐻(𝑦, 𝑑, 𝑙) = − ∑ 𝑝(𝜋𝑘)𝜋𝑘=𝑑! 𝜋𝑘=1 ln 𝑝(𝜋𝑘) …(6) when all motifs have equal probability, the largest value of 𝑃𝑒𝑟𝐸𝑛 is obtained, which has a value of ln 𝑑!, where 𝑑 = 3, 𝑙 = 1. in contrast, if there is only one 𝑝(𝜋𝑘) different from zero, which illustrates a completely regular signal, the smallest value of 𝑃𝑒𝑟𝐸𝑛 is obtained as much as 0 [36, 40, 41]. for 60 seconds, 𝑁 = 15360 samples, 6 windows of 10 second length (2560 samples) were extracted from the original eeg time series for each 19 channels. 2.5 statistical analysis the denoised 19 channels from the eeg dataset of 15 𝐻𝐶 , 15 𝑆𝑀𝐶𝐼 , and 5 𝑉𝐷 patients were preliminary divided into 5 recording regions that correspond to the scalp area of the cerebral cortex. the frontal includes seven channels: fp1, fp2, f3, f4, f7, f8 and fz, temporal includes four channels: t3, t4, t5 and t6, parietal includes three channels: p3, p4 and pz), occipital includes two channels: o1 and o2), and central includes three channels: c3, c4 and cz). the kolmogorov–smirnov test determined normality, while levene's test confirmed homoscedasticity. thus, spss 22 used two analysis of variance (anova) sections on 𝑆𝑝𝑒𝑐𝐸𝑛, 𝐴𝑝𝐸𝑛, and 𝑃𝑒𝑟𝐸𝑛 characteristics. each segment had two independent variables (ivs): the subject groups ( 𝐻𝐶 subjects, 𝑆𝑀𝐶𝐼 , and 𝑉𝐷 patients) and the five scalp regions (frontal, temporal, parietal, occipital, and central). one of the former attributes was the dependent variable (dv). all statistical tests were significant at p< 0.05. 2.6 dimensionality reduction using 𝐅𝐍𝐏𝐀𝐐𝐑 in order to maximize the distance between the centers of various classes while minimizing the distance between samples that belong to the same class, this study also used the fuzzy neighborhood preserving analysis with qr-decomposition ( 𝐹𝑁𝑃𝐴𝑄𝑅 ) dimensionality reduction technique [26] of khushaba et al [20]. 𝐹𝑁𝑃𝐴𝑄𝑅 maintains the contribution of samples to various classes in this way [26]. for the first time, our study used 𝐹𝑁𝑃𝐴𝑄𝑅 to distinguish between 𝐻𝐶 and demented participants during 𝑊𝑀 tasks. the matrix (𝐺𝐹𝑁𝐷𝐴𝑄𝑅) was built from the training set to project the input feature vector using 𝐹𝑁𝑃𝐴𝑄𝑅 . to reduce dimensionality, the projection matrix was multiplied by the training and testing sets. 𝐹𝑁𝑃𝐴𝑄𝑅 projected training data input feature vector. projecting the feature vector's testing set requires merely multiplying it by the projection matrix from the training data. figure 2 shows how the 𝐹𝑁𝑃𝐴𝑄𝑅 feature projection calculates the within-class scatter matrix (𝑆𝑊) and between-class scatter matrix (𝑆𝐵). calculates the within-class scatter matrix ( 𝑆𝑊 ) and between-class scatter matrix (𝑆𝐵). noor k. al-qazzaz al-khwarizmi engineering journal, vol. 19, no. 4, p.p. 2941(2023) 35 fig. 2. the steps of dimensionality reduction using 𝐅𝐍𝐏𝐀𝐐𝐑 in a comparative study, the 𝐹𝑁𝑃𝐴𝑄𝑅 dimensionality reduction approach and 𝑘 nn classifier were used to identify 𝑉𝐷 , 𝑆𝑀𝐶𝐼 , and 𝐻𝐶 subjects [5]. 2.7 channel selection using 𝐈𝐁𝐆𝐒𝐀 the most effective channels have been found, and the amount of information has been decreased, using the improved binary gravitation search algorithm ( 𝐼𝐵𝐺𝑆𝐴 ) optimization algorithm [25, 42]. 𝐺𝑆𝐴 is a powerful optimization technique that was first proposed in [43]. for use in addressing binary-valued problems. it was created based on the newtonian laws of gravity and motion. 𝑁 objects (agents) are defined for the 𝐼𝐵𝐺𝑆𝐴 algorithm to determine the best eeg channels. the population starts out with this collection of things. each object in this study is regarded as a binary vector with a dimension of 19. the number of eeg channels is the same as the dimension that was given. the following vector can be regarded as the 𝑖𝑡ℎ object. finding the item that gives the best fitness value is the main objective. equation 7 [44] can be used to calculate the classification accuracies for each set of eeg channels, which are used in this work to determine the 𝑓𝑖𝑡𝑛𝑒𝑠𝑠 values for the objects: 𝑓𝑖𝑡𝑖 = 𝜔1 × 𝑎𝑐𝑐𝑢𝑖 + 𝜔2 × [1 − ∑ 𝑓𝑗 𝑝 𝑗=1 𝑝 ] . . . (7) where 𝜔1, 𝜔2 are predefined weight factors, 𝜔1 is the weight factor for the classification accuracy of the 𝑘 nn classifiers respectively determined by the 10-fold cross-validation (𝐶𝑉) method; 𝑎𝑐𝑐𝑢𝑖 is the 1-nn classification accuracy; 𝜔2 is the weight factor for the number of selected features and 𝑓𝑗 is the value of the feature mask. if precision is the most crucial factor, the 𝑤𝑒𝑖𝑔ℎ𝑡 factor might be increased to a high amount (such as 100%). the position of the object with a high fitness value should be set suitably since it has a high likelihood of influencing the positions of the other objects in the following iteration [14,15]. equation 8 yields the 𝑎𝑐𝑐𝑢𝑖 , where corr is the number of cases that were properly classified and incorr is the number of examples that were classified wrongly [44]: 𝑎𝑐𝑐𝑢𝑖 = 𝑐𝑜𝑟𝑟 𝑐𝑜𝑟𝑟+𝑖𝑛𝑐𝑜𝑟𝑟 × 100% …(8) the ibgsa algorithm selects the most informative eeg channels for classification. the method selects the optimal eeg channel subset for classification. the technique optimizes channel selection to increase eeg-based classification accuracy and efficiency [43]. 2.8 dementia classification techniques the eeg signals were divided into (𝐻𝐶, 𝑆𝑀𝐶𝐼, and 𝑉𝐷) using a 𝑘nn classifier. the patients with 𝑉𝐷 made up a statistically significant minority in this analysis. to address the discrepancy, the researchers used a synthetic oversampling technique (smote) [45]. to prevent overfitting and bias in the classification analysis, the classifier parameters and the percentage of oversampling were evaluated by 10-fold cross-validation with a grid search approach [46]. the provided data set was partitioned into ten independent samples of similar size. only one of these groups was utilized to train the classifier, while the other nine were used as the test set. ten iterations of this process yielded ten reliable results. the 10-fold cv accuracy of this dataset was calculated as the mean of these accuracies [47]. since smote modifies the dataset, the oversampling was incorporated into the settings. because of this, it is possible that the parameters discovered with varying amounts of smote are not equivalent. when using the smote to normalize the class frequencies, we solely considered the training set [48, 49]. the classifier in this study was trained to find the best value of k, which was discovered to be k = 5, and to increase classification accuracy. each trial has been classified by 𝑘nn using the euclidean distance as a similarity metric. after selecting the optimal eeg channels, the 𝑘nn algorithm classifies background signals from symptomatic and asymptomatic instances using entropy. 𝑘 nn uses labeled training samples to classify data points. eeg signal entropy measures randomness or chaos. the 𝑘nn method classifies symptomatic and asymptomatic cases based on their resemblance to training samples by computing the entropy of chosen eeg channels [50]. 3. results and discussion 3.1 results of preprocessing stage figure 3 depicts the denoised eeg signals produced by the wt method. due to the heterogeneity of eeg artifacts, wt has been noor k. al-qazzaz al-khwarizmi engineering journal, vol. 19, no. 4, p.p. 2941(2023) 36 evaluated on every channel of the available eeg datasets. when comparing the original recorded eeg (red) with the suppressed version (blue), it is clear that the artifactual components were effectively eliminate fig. 3. the denoising resulting from the application of the wt technique to eeg ch2 which represents f8. 3.2 results of statistical analysis patients with 𝑉𝐷 showed less complexity than those with 𝑆𝑀𝐶i and 𝐻𝐶 using 𝑆𝑝𝑒𝑐𝐸𝑛, 𝐴𝑝𝐸𝑛 and 𝑃𝑒𝑟𝐸𝑛 as shown in figures 4, 5 and 6. for all patients, but especially for those with 𝐻𝐶 and 𝑉𝐷, the complexity of the eeg signals reduces as the condition worsens. figure 4 shows that the 𝑆𝑝𝑒𝑐𝐸𝑛 values of the 𝑉𝐷 patients were lower than those of the 𝑆𝑀𝐶𝐼 patients and that the 𝐻𝐶 patients' values were the greatest. moreover, the 𝑉𝐷 patients had lower 𝐴𝑝𝐸𝑛 values than the 𝑆𝑀𝐶𝐼 patients, and the 𝐻𝐶 subjects had the highest 𝐴𝑝𝐸𝑛 values (figure 5). finally, the patients with 𝑉𝐷 had lower 𝑃𝑒𝑟𝐸𝑛 values than those with 𝑆𝑀𝐶𝐼, and the participants with 𝐻𝐶 had the greatest value (figure 6). fig. 4. comparative plot of the 𝑺𝒑𝒆𝒄𝑬𝒏 for the five scalp regions of the brain for 𝑽𝑫, 𝑺𝑴𝑪𝑰 patients and 𝑯𝑪 subjects. fig. 5. comparative plot of the 𝑨𝒑𝑬𝒏 for the five scalp regions of the brain for 𝑽𝑫, 𝑺𝑴𝑪𝑰 patients and 𝑯𝑪 subjects. fig. 6. comparative plot of the 𝑷𝒆𝒓𝑬𝒏 for the five scalp regions of the brain for 𝑽𝑫, 𝑺𝑴𝑪𝑰 patients and 𝑯𝑪 subjects. noor k. al-qazzaz al-khwarizmi engineering journal, vol. 19, no. 4, p.p. 2941(2023) 37 3.3 results of dementia classification techniques the classification confusion matrix for all three schemes proposed is shown in tables i, ii and iii. table i illustrates the confusion matrix for the 𝑘nn classifier without using the 𝐹𝑁𝑃𝐴𝑄𝑅 and ibgsa. table ii shows the confusion matrix for the 𝑘 nn classifier with the 𝐹𝑁𝑃𝐴𝑄𝑅 dimensionality reduction technique. the number of selected features by the 𝐹𝑁𝑃𝐴𝑄𝑅 dimensionality reduction technique was set to 40 characteristics, which are the most essential features in terms of differentiating between patients suffering from 𝑉𝐷 and stroke-related 𝑆𝑀𝐶𝐼 and healthy control participants. table iii shows the confusion matrix for the 𝑘nn classifier with the ibgsa channels selection algorithm. the 𝑘 nn classification accuracy was improved from 86.67% to 88.09 using 𝐹𝑁𝑃𝐴𝑄𝑅 dimensionality reduction technique and 90.52 by ibgsa channel selection algorithm. the results suggested that ibgsa consistently improves 𝑊𝑀 discrimination of 𝑉𝐷, 𝑆𝑀𝐶𝐼 patients and 𝐻𝐶 subjects. therefore, ibgsa improves the classification over all accuracy for all three groups as in the 𝑘 nn classification over the 𝐹𝑁𝑃𝐴𝑄𝑅 accuracy. table 1, calculation of the confusion matrix for multi-class classification using the 𝒌nn classifier. 𝐜𝐨𝐧𝐟𝐮𝐬𝐢𝐨𝐧 𝐦𝐚𝐭𝐫𝐢𝐱 𝐕𝐃 𝐒𝐌𝐂𝐈 𝐇𝐂 𝑽𝑫 93.33% 6.67% 0.00% 𝑺𝑴𝑪𝑰 5.56% 93.33% 1.11% 73.33% 𝑯𝑪 16.67% 10% table 2, calculation of the confusion matrix for multi-class classification using 𝒌nn and the 𝑭𝑵𝑷𝑨𝑸𝑹 technique. 𝐜𝐨𝐧𝐟𝐮𝐬𝐢𝐨𝐧 𝐦𝐚𝐭𝐫𝐢𝐱 𝐕𝐃 𝐒𝐌𝐂𝐈 𝐇𝐂 𝑽𝑫 87.78% 11.11% 1.11% 𝑺𝑴𝑪𝑰 7.78% 92.22% 0.00% 𝑯𝑪 6.67% 16.67% 76.67% table 3, calculation of the confusion matrix for multi-class classification using 𝒌nn and the ibgsa technique. 𝐜𝐨𝐧𝐟𝐮𝐬𝐢𝐨𝐧 𝐦𝐚𝐭𝐫𝐢𝐱 𝐕𝐃 𝐒𝐌𝐂𝐈 𝐇𝐂 𝑽𝑫 67.78% 31.11% 1.11% 𝑺𝑴𝑪𝑰 7.78% 88.89% 3.33% 𝑯𝑪 3.33% 6.67% 90% as a result, 𝑘 nn was used in the study to support multi-class classification and to distinguish 𝑉𝐷, 𝑆𝑀𝐶𝐼 patients, and 𝐻𝐶 subjects. this study had several limitations, including a small sample size, and an additional analysis with a large database should be performed in the future. finally, we compared the proposed approach to other cutting-edge methods in the literature that employed the different dementia datasets as we did in our work. the results show that our model outperforms other existing methods in the literature, with the highest classification accuracy of 90.52% compared to kashefpoor et al. [9] proposed a methodology that obtained an accuracy of around 88%, sharma et al. [10] investigated different features for control vs. 𝑀𝐶𝐼 signal classification and obtained accuracy ranges between 73.2% and 89.8%. 4. conclusion the electroencephalogram (eeg) is a vital tool for studying mental processes. here, we analyze and filter eeg signals to identify promising channels and useful markers for an earlier, more accurate diagnosis of dementia. the wt method has been implemented as a denoising method. patients with 𝑉𝐷 and 𝑆𝑀𝐶𝐼 have had their irregularities assessed with 𝑆𝑝𝑒𝑐𝐸𝑛 , 𝐴𝑝𝐸𝑛 , and 𝑃𝑒𝑟𝐸𝑛 as characteristics. to improve 𝑊𝑀 categorization, we applied the 𝐹𝑁𝑃𝐴𝑄𝑅 dimensionality reduction technique in conjunction with the ibgsa channel selection algorithm. 𝐹𝑁𝑃𝐴𝑄𝑅 dimensionality reduction technique increased 𝑘 nn classification accuracy from 86.67% to 88.09%, while the ibgsa channel selection algorithm increased it to 90.52%. findings revealed that ibgsa reliably enhances 𝑊𝑀 discrimination in 𝑉𝐷 , 𝑆𝑀𝐶𝐼 patients, and 𝐻𝐶 controls. because of these findings, it is clear that minimizing the number of channels used in the ibgsa selection process has a substantial impact on improving classification accuracy. working memory stores and manipulates information for ongoing tasks. dementia causes cognitive deterioration, including working memory loss. therefore, working memory enhancement may slow dementia-related cognitive deterioration. working memory training may increase brain activity in working memory-related areas, however, healthy volunteers trained working memory using an adaptive n-back task. the training did not directly cause changes in brain activation in several important locations. in spite of that, studies have noor k. al-qazzaz al-khwarizmi engineering journal, vol. 19, no. 4, p.p. 2941(2023) 38 implied that working memory training may have benefits, but more study is needed to determine the long-term consequences. working memory training alone may not diminish dementia-related brain activity since dementia is complicated. working memory training may also be affected by dementia stage, type, and training procedure. in general, improving working memory in people who have dementia continues to be our focus of research. future studies may provide additional insights into effective interventions and techniques to improve cognitive function and quality of life. references [1] b. c. campbell, d. a. de silva, m. r. macleod, s. b. coutts, l. h. schwamm, s. m. davis, et al., "ischaemic stroke," nature reviews disease primers, vol. 5, p. 70, 2019. 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(2023) 29-41، صفحة 4، العدد19المجلد جلة الخوارزمي الهندسيةم القزازنور كمال 41 تحسين تصنيف الذاكرة العاملة لنشاط تخطيط الدماغ في الخرف: دراسة مقارنة ** شوال حميد بن محمد علي نور كمال القزاز * ***سيتي أنوم أحمد العراق /بغداد /جامعة بغداد /كلية الخوارزمي للهندسة /قسم الهندسة الطبية الحيوية* ماليزيا /سيالنغور /قسم الهندسة الكهربائية واإللكترونية والنظم، كلية الهندسة والبيئة المبنية، جامعة كيبانغسان ماليزيا ** ماليزيا /سيالنغور /ماليزيا /جامعة كيبانغسان /قسم الهندسة الكهربائية واإللكترونية وهندسة النظم /مركز الهندسة اإللكترونية وهندسة االتصاالت المتقدمة ماليزيا /سيالنغور /جامعة بوترا ماليزيا /كلية الهندسة /قسم الهندسة الكهربائية واإللكترونية*** ماليزيا /سيالنغور /سيردانغ /جامعة بوترا ماليزيا /المعهد الماليزي لبحوث الشيخوخة noorbme@kecbu.uobaghdad.edu.iq *البريد االلكتروني: sawal@ukm.edu.my *البريد االلكتروني:* sanom@upm.edu.my *البريد االلكتروني:** الخالصة (، وخمسة عشر مريًضا بعد السكتة vd( في خمسة مرضى يعانون من الخرف الوعائي )wmالعاملة )لغرض من التحقيق الحالي هو التمييز بين الذاكرة (. تم توضيح eeg( بناًء على الخلفية نشاط تخطيط كهربية الدماغ )hc(، وخمسة عشر فردًا سليًما للتحكم )mciالدماغية يعانون من ضعف إدراكي خفيف ) (، apen( في هذه الدراسة. في الدراسة الحالية، تم استكشاف اإلنتروبيا الطيفية )wtباستخدام التعديل المسبق للموجات ) eegالتخلص من القطع األثرية (، تم إجراء دراسة 𝑘nnأقرب الجيران )-kباستخدام مخطط تصنيف wm(. لتحسين تصنيف specen(، واإلنتروبيا التقريبية )perenوإنتروبي التبديل ) كتقنية لتقليل األبعاد وتحسين البحث عن الجاذبية الثنائية qr-decomposition (fnpaqr)دام تحليل الحفاظ على الحي الغامض باستخدام مقارنة الستخ (ibgsa تمت زيادة دقة تصنيف .)𝑘nn باستخدام تقنية تقليل األبعاد 90.52٪ و 88.09٪ إلى 86.67من ٪fnpaqr وخوارزمية اختيار قنوات ibgsaى التوالي. وفقًا للنتائج، يعزز ، علibgsa بشكل موثوق التمييز فيwm للمشاركين فيhc وmci وvd لذلك، توفر .wt وميزات اإلنتروبيا .mciو vdللمرضى الذين يعانون من eegمؤشًرا صحيًحا للخرف للبحث عن نشاط خلفية 𝑘nnومصنف ibgsaو mailto:noorbme@kecbu.uobaghdad.edu.iq mailto:sawal@ukm.edu.my mailto:sanom@upm.edu.my abstract keywords: dementia, wavelet, entropy, dimensionality reduction, channels selection, features, classification. 1. introduction 2. materials and methods 2.1 participants 2.2 eeg recording 2.3 preprocessing stage 2.4 features extraction stage 2.5 statistical analysis 2.6 dimensionality reduction using 𝐅𝐍𝐏𝐀𝐐𝐑 2.7 channel selection using 𝐈𝐁𝐆𝐒𝐀 2.8 dementia classification techniques 3. results and discussion 3.1 results of preprocessing stage 3.2 results of statistical analysis 3.3 results of dementia classification techniques 4. conclusion references this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 19, no. 4, december, (2023) p. p. 6777 development of an ann model for rgb color classification using the dataset extracted from a fabricated colorimeter shahad a. mnati* furat i. hussein** ahmed issa*** *, **department of mechatronics engineering/ al-khwarizmi college of engineering/ university of baghdad, baghdad/ iraq *** department, faculty of engineering and information technology/mechatronics and medical devices engineering alazhar university – gaza/ gaza 1277/ palestine corresponding author: *email: shahed.ali1202a@kecbu.uobaghdad.edu.iq **email: furatnejjar@uobaghdad.edu.iq ***email: a.issa@alazhar.edu.ps (received 21 may 2023; accepted 11 september 2023) https://doi.org/10.22153/kej.2023.09.003 abstract codes of red, green, and blue data (rgb) extracted from a lab-fabricated colorimeter device were used to build a proposed classifier with the objective of classifying colors of objects based on defined categories of fundamental colors. primary, secondary, and tertiary colors namely red, green, orange, yellow, pink, purple, blue, brown, grey, white, and black, were employed in machine learning (ml) by applying an artificial neural network (ann) algorithm using python. the classifier, which was based on the ann algorithm, required a definition of the mentioned eleven colors in the form of rgb codes in order to acquire the capability of classification. the software's capacity to forecast the color of the code that belongs to an object under detection is one of the results of the proposed classifier. the work demanded the collection of about 5000 color codes which in turn were subjected to algorithms for training and testing. the open-source platform tensorflow for ml and the open-source neural network library keras were used to construct the algorithm for the study. the results showed an acceptable efficiency of the built classifier represented by an accuracy of 90% which can be considered applicable, especially after some improvements in the future to makes it more effective as a trusted colorimeter. keywords: colorimeter, rgb classifier, ann, tensorflow, ml. 1. introduction advanced methods like ml algorithms can be employed to address the color classification issue. neural network methods are replacing older statistical methods and algorithms in the field of machine vision. due to weak planning, the latter encounters numerous challenges that raise obstacles when developing an ml model for the computer vision system. executives frequently set challenging goals for the data science team during the planning process. neural network techniques, as opposed to conventional algorithms, are typically quite beneficial for certain challenges [1]. one of the simplest non-parametric methods of color recognition is color categorization, utilizing the k-nearest neighbors (knn) algorithm with feature extraction. most real-world datasets do not conform to mathematical theoretical assumptions and this will be very useful in practice. classification is widely regarded as one of the most extensively studied problems within the domains of ml and data mining. despite its wellestablished status in the field of ml, classification encounters challenges such as effectively managing missing data [2]. the k-mean algorithm mailto:shahed.ali1202a@kecbu.uobaghdad.edu.iq mailto:furatnejjar@uobaghdad.edu.iq mailto:a.issa@alazhar.edu.ps https://doi.org/10.22153/kej.2023.09.003 shahad a. mnati al-khwarizmi engineering journal, vol. 19, no. 4, p.p. 6777 (2023) 68 is another well-known ml approach that can be used to extract colors from photographs and categorize each image from a collection of images based on color space values. any color space can be utilized such as rgb, cymk, hsv, etc. [3]. kusumo b.s. et al. [4] used rgb image processing properties in classifying corn diseases, which are one of indonesia's most significant crops. oriented fast and rotated brief (orb), scale-invariant feature transform (sift), and speeded-up robust features were used to extract the features (surf). the categorization was performed using decision tree (dt), naive bayes (nb), support vector machines (svm), and random forest (rf). behera s.k. et al. [5] have classified disease and the severity of disease in oranges using the svm algorithm with the assistance of the k-mean clustering approach and fuzzy logic. the suggested framework demonstrated an accuracy of 90% in illness categorization and severity assessments. kumari, r. s. s. et al. [6] attempted a traditional method of classifying fruit that relies on manual operations and visual acuity. the svm classifiers classify based on statistical and co-occurrence features derived from the wavelet transform. the accuracy of classification for the proposed system is 95.3%. panigrahi, k.p. et al. [7] proposed machine learning methods such as decision tree (dt), random forest (rf), support vector machine (svm), naive bayes (nb), and k-nearest neighbor (knn) to be used to diagnose crop diseases using plant images. when compared to other classification algorithms, the rf algorithm obtains the highest accuracy of 79.23%. hameed, n. et al. [8] followed a method of intelligent digital diagnosis that improved the classification precision of multiple diseases. the diagnostic accuracy is 96.47% using a multi-class multi-level (mcml) classification algorithm evaluated on 3672 classified images collected from various sources. nagata, t. et al. [9] classified skin tears using a machine learning method to identify the skin layers using digital rgb color and subsequently treat the wound. the determination of the wound layer showed an accuracy of 74% and 71% for the svm and rf respectively. the aim of the current study is to employ the ann algorithm in order to build an ml model that acts as a classifier and has a good opportunity to predict the colors of different objects based on datasets extracted from a lab-fabricated colorimeter. 2. materials and methods 2.1 dataset collection the dataset employed in the study was extracted from an rgb colorimeter device (figure 1) implemented in the lab using a number of low-cost electronics, electrical parts, and other complementary components. in this process, the fabricated colorimeter was designed with specific consideration and high precision to measure the rgb values of a number of colored samples in order to use these values as input for the proposed ann model. the number of tested samples is about 5000 cards of colored paper stamped with standard names for wallpaper and paint companies in iraq, namely jotun, al-marjan, al-yaqut, and jazeera. the colorimeter was used to record the code of each inspected colored card as rgb code and save it as a comma-separated values (csv) file. fig. 1. the fabricated colorimeter and standard colored cards 2.2 rgb and color spaces in essence, a color space is a collection of colors that assist in reproducing analog and digital representations of color along with physical device profiling. another way to think of color spaces is as an abstract mathematical model that enables the representation of colors as numbers [10]. the rgb system-dependent color space is represented by 24bit, with 8 bits allotted to each single channel of r, g, and b. as a result, the range of values for each channel is 0 to 255. all colors can be represented shahad a. mnati al-khwarizmi engineering journal, vol. 19, no. 4, p.p. 6777 (2023) 69 using various red, green, and blue hues, according to this color space paradigm. 2.3 ann technology ann is essentially a mathematical representation of a process that was created empirically rather than by employing mass and energy balances surrounding the process. a neural network is made up of a network of partially interconnected processing units, or nodes, structured in layers, much like the neurons in the brain. they also feature connections between the nodes of subsequent layers. the fundamental structure of a single neuron or node is within a neural network model with inputs, activation functions, and a single output. weights are calculated values that represent the relationships between nodes [11, 12]. figure 2 shows a schematic diagram of a fundamental neural network where 𝑌𝑖 is the output, and w are the weights that represent the "strength" of the connections between the neurons. each neuron in the hidden layer receives weighted inputs plus bias from each neuron in the preceding layer [13]: fig. 2. schematic diagram of fundamental neural network [12] 𝑍𝑖 = ∑ 𝑋𝑘 𝑗−1𝑊𝑘,𝑖 − 𝑏𝑘 𝑁𝑗−1 𝑘=1 … (1) where 𝑊𝑘,𝑖is the weight of the link between 𝑛𝑜𝑑𝑒 and all the nodes in the preceding layers, 𝑏𝑘 is the bias to the node, 𝑁𝑗−1 is the number of nodes in layer 𝑗 − 1, and 𝑋𝑘 𝑗−1 signifies the input which in this case is the (rgb) values from the 𝑘 − 𝑡ℎ node in the 𝑗 − 𝑡ℎ layer. the summation of equation 1 is fed to the activation function, which generates the node's output, which is calculated as 𝑌𝑖 = 𝑓(𝑍𝑖) which is one of the eleven fundamental color categories (red, green, orange, yellow, pink, purple, blue, brown, grey, white, or black). the activation function for each layer in the neural network (nn) model is a rectified linear unit (relu) which has been applied in the current work. the activation functions are used to introduce non-linearity in order to assist the nn in learning complex data patterns. 2.4 performance metrics various metrics are employed for the estimation of an ann performance and quality. performance metrics were considered in this study for evaluating the performance of the ml model. different metrics are used in evaluating the performance of the model such as accuracy, precision, recall, and f1score [14, 15]: 2.4.1 accuracy (acc): the accuracy of a model determines how well it classifies the target variable. the accuracy of the selected model is given as follows [16]: 𝐴𝑐𝑐 = 𝑇𝑃 + 𝑇𝑁 𝑇𝑃 + 𝑇𝑁 + 𝐹𝑃 + 𝐹𝑁 … (2) where tp is the total positive which refers to the number of accurately labeled positive samples, tn is total negative which refers to the number of negative samples that have been accurately classified, fp is the false positive which refers to the misclassification of negative samples as positive, and fn is the false negative which refers to the misclassification of positive samples as negative. 2.4.2 precision (prec) is the proportion of correctly predicted positives to the total number of positive observations predicted. a low rate of false positives is correlated with precision [16]: 𝑃𝑟𝑒𝑐 = 𝑇𝑃 𝑇𝑃 + 𝐹𝑃 … (3) 2.4.3 recall (rec): is the proportion of positively predicted observations to the total number of observations in the actual class. in general, recall values above 0.5 are considered acceptable [16]: 𝑅𝑒𝑐 = 𝑇𝑃 𝑇𝑃 + 𝐹𝑁 … (4) 2.4.4 f1 score (f1s): is the harmonic mean of precision and recall, it is a more accurate measurement than precision [16]: 𝐹1s = 2 × 𝑃𝑟𝑒𝑐 − 𝑅𝑒𝑐 𝑃𝑟𝑒𝑐 + 𝑅𝑒𝑐 … (5) where f1-score is the most effective measurement when the target's classification is imbalanced. shahad a. mnati al-khwarizmi engineering journal, vol. 19, no. 4, p.p. 6777 (2023) 70 2.4.5 confusion matrix: is used to summarize the performance of the ann algorithm. to discriminate between the rgb classes (black, white, …, etc.), the actual colors are assigned to positive and negative. however, the prediction colors are assigned to true for and false for no damage [17] as shown in figure 3. the primary goal of the model is to optimize the true positives and true negatives, while minimizing the false positives and false negatives to achieve optimal performance. the total number of predictions is equal to the summation of tp, tn, fp and fn. fig. 3. confusion matrix for a binary classifier. 2.5 methodology development for ann in short, an ann model consists of five layers stacked sequentially. each layer is composed of a number of neurons. each neuron of the first layer takes the input feature (the red, green, and blue values), multiplies it by its initial weight, calculates the total number of each neuron together with the bias, and then passes it through the activation function to the next layer of neurons, giving the result again as an input to the next layer. figure 4 shows the segments of the proposed ann as follows:  the initial layer consists of three neurons, which collectively possess a total of 12 parameters. these parameters include 9 weights and three biases. the second layer, consisting of 24 neurons, contains a total of 96 parameters. these parameters are comprised of 72 weights and 24 biases. 2.6 analytical framework python v2.13.0 was used to build, train, and validate the model using tensorflow v2.13.0 and keras libraries. tensorflow uses a single data flow diagram to represent all machine learning computations and states. the experimental data collected from the colorimeter device is employed as an input for the ml algorithm. the ann model has five layers. it is a densely connected neural network in the dense layer, also known as a fully connected layer, and is a fundamental component of neural networks. it is characterized by a deep interconnection structure, wherein each neuron within the dense layer receives input from every neuron in the preceding layer. the dense layer is employed in this model, making it a widely utilized component. the dense layer conducts matrix-vector multiplication in the underlying process. the values employed within the matrix are, in fact, parameters that possess the capability to be trained and adjusted through the utilization of backpropagation. fig. 4. the proposed ann configuration. shahad a. mnati al-khwarizmi engineering journal, vol. 19, no. 4, p.p. 6777 (2023) 71 fig. 5. the methodology of the proposed ann. fig. 6. confusion matrix correlation before training. shahad a. mnati al-khwarizmi engineering journal, vol. 19, no. 4, p.p. 6777 (2023) 72 3. results and discussion results are obtained through a number of sequential steps in order to achieve and present the color classification. in the first step, the dataset is obtained from the measurement of the colored cards using the fabricated colorimeter and by recording the rgb codes manually. after that, preprocessing is applied in order to label and modify the null data. the training and validation phase is the subsequent step which is started by adjusting the classification settings of the algorithm. the prediction phase comes in order to confirm the accuracy of the trained model. eventually, the performance metrics for the algorithm are applied with a view to evaluate results. figure 6 shows the manner of data correlation before the training phase. the graphical correlation of the rgb data is presented in this section. it is important to mention that the dataset was split into training data, testing data, and the setup of the ann layers which requires the use of proper neural network settings to get better results. the confusion matrix is used to evaluate the performance of a classifier using python software. actual labels are represented by rows, while the predicted labels are represented by columns. to get better classification results, the ann algorithm was adjusted at certain settings such as the number of epochs = 5001, verbose=0, batch_size = 2048, and validation_split = 0.2. the relationship between training and validation versus the no. epochs are shown in figure 6. here, the ‘epochs’ means the number of times at which the model iterates over the entire x and y data while training. batch size is the number of samples after which the parameters are updated while training. verbose is used for displaying the training progress. fig. 7. the accuracy of the training process of the ann model. moreover, the loss of the ann model is shown in figure 6 which indicates that the accuracy is improving during the training phase. also, it can be seen that both training and validation accuracies are matched at 90% which means that the classification algorithm is efficient. fig. 8. the loss of the training process of the ann model. in addition to the training and validation of the data, the built and saved ann model was used in the prediction phase. figure 9a shows the visualization of the actual values and the predicted values based on the ann model training data. the visualization of the actual values and predicted values of the tested data after using the ann model showed an acceptable match as seen in figure 9b. (a) (b) fig. 9. the prediction of the trained model and b) tested model. shahad a. mnati al-khwarizmi engineering journal, vol. 19, no. 4, p.p. 6777 (2023) 73 figure 10 shows the confusion matrix of the trained data for the labeled color. looking at the first value (158) gives a piece of information that the model predicts the presence of 158 unique shades of red. as seen in the figure, the first pink value in the sixth row is 16, which means there are 16 instances of pink incorrectly identified as red. table 1 tabulates the values of performance measures for the trained data. it can be seen that the ml model correctly predicts the color green 96% of the time, as well as other colors with different percentages, with an accuracy of 89% for all eleven classes. table 1, the performance measures the trained model. fig. 10. confusion matrix correlation after training. figure 11 shows the confusion matrix of the tested data for labeled colors. it is well known that this model predicts the existence of thirty-six unique shades represented by the first value of red (36). the first pink value in the sixth row is six, which means that there were 6 instances in which pink was incorrectly identified as red. table 2 tabulates the values of the performance measures of the tested data. it can be seen that the ml model correctly predicts the color green 94% of the time, as well as other colors with different percentages, and has an accuracy of 90% for all eleven classes. precision recall f1score support red 0.79 0.83 0.81 190 green 0.96 0.95 0.95 1168 blue 0.94 0.93 0.93 885 yellow 0.87 0.80 0.83 225 orange 0.81 0.83 0.82 167 pink 0.89 0.83 0.86 451 purple 0.82 0.86 0.84 450 brown 0.84 0.91 0.87 311 grey 0.73 0.80 0.76 144 black 0.88 0.88 0.88 16 white 0.70 0.58 0.64 24 accuracy 0.89 4004 macro avg 0.84 0.84 0.84 4004 weighted avg 0.89 0.89 0.89 4004 shahad a. mnati al-khwarizmi engineering journal, vol. 19, no. 4, p.p. 6777 (2023) 74 the general evaluation of the trained model is good with acceptable performance represented by an accuracy of 89% which may be improved by working with more epochs. the tested data showed an accuracy of 90% and better performance metrics in the colors green, blue, black, white, and purple. fig. 11. confusion matrix correlation after testing. table 2, the performance measures the tested model. 4. conclusion in this work, a proposed ann model offers a non-parametric, user-friendly, comprehensive alternative to traditional statistical methods used in classifying rgb colors. about 5000 samples of rgb colors were utilized to create the dataset by applying measurements to a number of standard colored cards through a lab-designed and implemented colorimeter. the dataset has been preprocessed to eliminate some unidentified samples that are considered null data. the established neural network has been well set to provide a better classification of ann settings. the whole amount of data was split into 80% trained data and 20% tested data. the data has been trained and validated with a high level of accuracy and performance. the results exhibit that the classification of unknown color grades can be applied with an accuracy of 90% which can be precision recall f1score support red 0.70 0.95 0.81 22 green 0.94 0.96 0.95 150 blue 0.96 0.93 0.94 109 yellow 0.83 0.68 0.75 28 orange 0.81 0.72 0.76 18 pink 0.85 0.87 0.86 47 purple 0.90 0.89 0.90 64 brown 0.90 0.79 0.84 34 grey 0.80 0.91 0.85 22 black 1.00 1.00 1.00 7 white 1.00 1.00 1.00 4 accuracy 0.90 505 macro avg 0.88 0.88 0.88 505 weighted avg 0.90 0.90 0.90 505 shahad a. mnati al-khwarizmi engineering journal, vol. 19, no. 4, p.p. 6777 (2023) 75 extended to more than 11 classes of colors and different datasets. the proposed model can be utilized as a reference in choosing and identifying the proper color in many applications such as car painting, by linking the colorimeter with the color mixers in order to mix the three primary rgb colors into any grade of the eleven previously mentioned colors. references [1] j. sainui and p. pattanasatean, “color classification based on pixel intensity values,” 2018 19th ieee/acis international conference on software engineering, artificial intelligence, networking and parallel/distributed computing (snpd), jun. 2018, doi: 10.1109/snpd.2018.8441141. 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(2023) 67-77، صفحة 4، العدد19المجلد الخوارزمي الهندسيةجلة مشهد علي مناتي 77 rgbلوان اللتصنيف أ (ann)الشبكة العصبونية االصطناعية تطوير نموذج مصنعمجموعة البيانات المستخرجة من مقياس ألوان باستخدام **فرات ابراهيم حسين *شهد علي مناتي ***حمد عيسىأ الميكاترونكس/ كلية هندسة الخوارزمي/ جامعة بغداد/ بغداد/ العراق*,** قسم هندسة ***قسم هندسة الميكاترونكس واالجهزة الطبية/ مؤسسة الهندسة وتكنولوجيا المعلومات/ جامعة االزهر/ غزة/ فلسطين shahed.ali1202a@kecbu.uobaghdad.edu.iq :البريد االلكتروني* furatnejjar@uobaghdad.edu.iq :البريد االلكتروني** a.issa@alazhar.edu.ps :البريد االلكتروني*** الخالصة من جهاز قياس األلوان الُمصنع في المختبر لبناء ُمصنف مقترح لتصنيف أخوذة( المrgbزرق )خضر واالحمر واالااللوان اال تم استخدام قيم بيانات الدراسة وهي األحمر واألخضر د اجراءعنبناًء على فئات محددة من األلوان األساسية. تم أخذ األلوان األساسية والثانوية والثالثية في االعتبار جسامألوان اال ( من خالل تطبيق خوارزمية الشبكة العصبونية mlوالبرتقالي واألصفر والوردي واألرجواني واألزرق والبني والرمادي واألبيض واألسود في التعلم اآللي ) كتسابمن أجل ا rgbشكل أكواد علىالمذكورة تعريف األلوان األحد عشر ann(. تطلب المصنف الذي اعتمد على خوارزمية annاالصطناعية ) . تطلب فحص والتحققالبرنامج الذي يعتمد على المصنف المقترح القدرة على التنبؤ بلون الكود الذي ينتمي إلى كائن قيد ال مخرجاتالقدرة على التصنيف. ومكتبة mlلـ tensorflowقيمة لونية تم إخضاعها بدورها لخوارزميات التدريب واالختبار. تم استخدام المنصة مفتوحة المصدر 5000العمل جمع حوالي ٪ والتي يمكن اعتبارها90قدرها إلنشاء خوارزمية الدراسة. أظهرت النتائج كفاءة مقبولة للمصنف المبني ممثلة بدقة kerasالشبكة العصبية مفتوحة المصدر قابلة للتطبيق خاصة بعد بعض التحسينات في األعمال المستقبلية لتكون أكثر فاعلية كمقياس ألوان موثوق به. mailto:shahed.ali1202a@kecbu.uobaghdad.edu.iq*البريد mailto:shahed.ali1202a@kecbu.uobaghdad.edu.iq*البريد mailto:furatnejjar@uobaghdad.edu.iq**البريد mailto:furatnejjar@uobaghdad.edu.iq**البريد mailto:a.issa@alazhar.edu.ps***البريد mailto:a.issa@alazhar.edu.ps***البريد 2. materials and methods fig. 1. the fabricated colorimeter and standard colored cards 2.2 rgb and color spaces 2.3 ann technology ann is essentially a mathematical representation of a process that was created empirically rather than by employing mass and energy balances surrounding the process. a neural network is made up of a network of partially interconnected processing units... where ,𝑊-𝑘,𝑖.is the weight of the link between 𝑛𝑜𝑑𝑒 and all the nodes in the preceding layers, ,𝑏-𝑘. is the bias to the node, ,𝑁-𝑗−1. is the number of nodes in layer 𝑗−1, and ,𝑋-𝑘-𝑗−1. signifies the input which in this case is the (rgb)... 2.4 performance metrics various metrics are employed for the estimation of an ann performance and quality. performance metrics were considered in this study for evaluating the performance of the ml model. different metrics are used in evaluating the performance of the model ... the second layer, consisting of 24 neurons, contains a total of 96 parameters. these parameters are comprised of 72 weights and 24 biases. the experimental data collected from the colorimeter device is employed as an input for the ml algorithm. the ann model has five layers. it is a densely connected neural network in the dense layer, also known as a fully connected layer, and is a funda... fig. 6. confusion matrix correlation before training. 3. results and discussion fig. 9. the prediction of the trained model and b) tested model. fig. 10. confusion matrix correlation after training. 4. conclusion in this work, a proposed ann model offers a non-parametric, user-friendly, comprehensive alternative to traditional statistical methods used in classifying rgb colors. about 5000 samples of rgb colors were utilized to create the dataset by applying me... references [1] j. sainui and p. pattanasatean, “color classification based on pixel intensity values,” 2018 19th ieee/acis international conference on software engineering, artificial intelligence, networking and parallel/distributed computing (snpd), jun. 2018,... [2] a. a. soofi and a. m. awan, “classification techniques in machine learning: applications and issues,” journal of basic and applied sciences, vol. 13, pp. 459–465, jan. 2017, doi: 10.6000/1927-5129.2017.13.76. this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 20, no. 2, june, (2024), p p. 8693 enhanced gait phases recognition by emg and kinematics information fusion and a minimal recording setup rami mobarak*, alessandro mengarelli**, federica verdini***, sandro fioretti****, laura burattini***** and andrea tigrini****** *,**,***,****,*****,******department of information engineering, università politecnica delle marche, ancona, italy corresponding author: *email: r.mobarak@pm.univpm.it **email: a.mengarelli@staff.univpm.it ***email: f.verdini@staff.univpm.it ****email: s.fioretti@staff.univpm.it *****email: l.burattini@pm.univpm.it ******email: a.tigrini@staff.univpm.it (received 6 may 2024; accepted 27 may 2024; published 1 june 2024) https://doi.org/10.22153/kej.2024.05.002 abstract the limited mobility of lower limb amputees highlights the need for advancements in prosthetic control strategies to restore natural locomotion. this paper proposes an information fusion approach for gait phase recognition using surface electromyography (semg) and kinematics data. time-domain (td) features were extracted from the myoelectric data and three data-driven models, specifically support vector machine (svm), k-nearest neighbours (knn), and artificial neural network (ann), were compared in three different input conditions i.e. semg features, hip angle, and their fusion. gait phase estimation results averaged from 40 healthy participants during normal walking with 10 strides per each demonstrated that the proposed fusion approach has consistently outperformed (p<0.0001) the other two conditions achieving a maximum accuracy of 85.48% with svm. the findings suggest promising applications in prosthetic motion control and rehabilitative exoskeletons, highlighting the potential for improved user-driven strategies in lower limb prostheses. keywords: semg; kinematics; svm; prosthetic control; gait; information fusion 1. introduction lower limb amputation is a widespread concern globally, affecting millions of individuals, especially those with transfemoral (tf) amputations [1]–[3]. diabetes, vascular diseases, and injuries are the principle causes of such amputations [2]. passive prostheses were initially used to compensate for the limb function loss but they imposed limitations on walking symmetry and metabolic cost [4], [5]. therefore, literature underlined the necessity for improving user-driven control strategies in lower limb prostheses, to allow amputees to regain their natural locomotion abilities [1], [3], [6], [7]. surface electromyography (semg) and mechanical signals serve as the main sources of information for the high-level control of prostheses and exoskeletons [4], [8]. mechanical signals are deterministic signals that appear as a result of the motion, while the myoelectric activity has a stochastic nature and precedes the occurrence of the motion, thus reflecting the user intention [3], [9]–[12]. although previous studies have employed either one of these signals [3], [6], [13]–[15] recent literature indicates that enhanced motion prediction performance can be achieved through the fusion of myoelectric and mechanical information [9], [16]. such an approach leverages the predictive nature of semg signals and the stability offered by the mechanical information for an improved decision output [9], [11], [16]. the decoding of motion from the relevant biosignals can be broadly categorized mailto:r.mobarak@pm.univpm.it mailto:a.mengarelli@staff.univpm.it mailto:f.verdini@staff.univpm.it mailto:s.fioretti@staff.univpm.it mailto:l.burattini@pm.univpm.it mailto:a.tigrini@staff.univpm.it https://doi.org/10.22153/kej.2024.05.002 rami mobarak al-khwarizmi engineering journal, vol. 20, no.2, p.p. 8693(2024) 87 into physical-based models and data-driven approaches [3], [8]. in the former, complex physical relationships must be explicitly expressed, and subject-specific parameters optimization is required, thus imposing limitations on running latency and tolerable complexity for real-time applications [8], [12], [17]. the data-driven approaches are further subcategorized into two main classes: pattern recognition and regression [3], [8]. in pattern recognition, also known as classification, the decoded motor tasks are divided into a finite number of clusters of pre-planned trajectories [6], [8]. although it’s burdened by the incapability to generalize to unseen motor tasks, this approach was largely employed by previous studies, due to its promising performances [9], [18]. on the other hand, regression approaches involve direct decoding of the signal information into continuous output variables, thus being more adaptive to different contexts, providing higher autonomy to the user [8], [18]. this approach remains challenging in a practical context, due to the high non-linearity between the myoelectric information and the targeted joint angle or torque that limits the prediction accuracy [8]. walking is a cyclic motor task constituted of sequential gait events, each of them characterized by a specific motor program, involving coordinated muscular activity aimed to flex or extend specific joints during a gait cycle [19], [20]. this suggests that dividing the gait cycle into several phases and leveraging semg information to infer them could achieve high prediction performance that allows for natural motion patterns and seamless transition between subphases of walking [4], [19]. in this context, luo et al. [19] have fed a long short-term memory (lstm) deep learning model with 4 thigh muscles semg signals to estimate 4 subphases of the gait cycle, providing an average accuracy of around 90% during treadmillconstrained speed walking. although high accuracy is attained, the estimation performance could be reduced in an uncontrolled context such as normal walking due to the constraints imposed on muscle activations in the treadmill case [21]. in [22], support vector (svm) the model was employed to predict 5 gait subphases using 3 imu data acquired from the thigh, shank, and foot with a classification accuracy of about 90%. although the promising classification performance, it lacks the applicability on tf amputees, since it utilizes sensors attached below the knee. furthermore, mobarak et al. [16] have recently shown that fusing hip joint flexion-extension angle with thigh myoelectric information provides consistent improvement in ankle position control through a regression approach. these studies lack the investigation of neuromechanical information fusion acquired exclusively from the proximal part of the lower limbs in gait phase recognition during normal walking and using shallow models. therefore, the two main hypotheses investigated in this study are as follows:  thigh muscle's myoelectric activity carries sufficient information to infer gait phases using data-driven algorithms during unconstrained walking.  the fusion of the hip joint angle in the sagittal plane with the semg signals could significantly boost the estimation accuracy. in this study, conventional time domain (td) features were extracted from the thigh semg due to their robustness and real-time applicability [25]. three data-driven models widely adopted in literature were employed to predict the gait phases including k-nearest neighbours (knn) [3], svm [22], and artificial neural network (ann) [9]. 2. materials and methods a. data description the data used in this study is a publicly available dataset acquired at shenzhen institute of advanced technology, chinese academy of sciences [23], in which 9 semg signals of the lower limbs muscles of 40 healthy participants (30 males and 10 females) with an average age of 24.5 years were acquired at 1920 hz. raw markers data and ground reaction force were also recorded using motion capture system sampling at 60 hz and force platforms at 1920 hz respectively. the markers data was upsampled to match the force data and were used to compute joint kinematics and kinetics [23]. in the experimental protocol of their dataset, several lower limb motor tasks were performed by the subjects. what is of concern in this study is the normal walking task, which includes 10 walking trials from each subject acquired separately [23]. the kinematics and kinetics information was then used to segment the gait cycle into 5 subphases that lie between the following 6 consecutive gait events: heel-strike (hs), maximum knee stance flexion (msf), maximum knee stance extension (mse), toe-off (to), maximum knee swing flexion (mwf), and the next cycle hs as in fig. 1 [23]. in this study, only the hip joint flexion-extension angle and 4 semg signal of the thigh muscles were considered since they mainly focused on gait phase pattern recognition using the minimal amount of information acquired from the proximal part of the rami mobarak al-khwarizmi engineering journal, vol. 20, no.2, p.p. 8693(2024) 88 lower limb. these thigh muscles are tensor fascia lata (tfl), rectus femoris (rf), vastus medialis (vm), and semimembranosus (sm), which have different roles during the stance and swing phases [19]. a. preprocessing and feature extraction butterworth fourth-order bandpass filter between 10 hz and 400 hz cutoff frequencies was employed to remove the noise from the myoelectric signals. td features including root mean square (rms), mean absolute value (mav), and waveform length (wl) were extracted from the semg signal windows that were segmented with a length of 150 samples and sliding increment of 40 samples. the hip joint angle and gait phase label were both downsampled by a factor of 40 to match the final update rate of 48 hz which is very suitable for real-time purposes [24]. the td features were considered due to their light computational cost and suitability for real-time applications [25]. both the hip joint angle and the extracted features were normalized using z-score normalization, as in eq. (1): 𝛀𝒏 = 𝛀 − 𝛍 𝛔 … (𝟏)  fig. 1. the black curve represents a plot of the knee flexion-extension angle during a single gait cycle with the vertical blue dashed bars indicating the main gait events separating the subphases written on the plot. where ωn and ω are respectively the normalized and non-normalized feature, μ is the mean of the corresponding feature data from the training sets, and σ is its standard deviation. training and testing hip joint angle and myoelectric features data were normalized using the mean and standard deviation calculated from the training set. a flowchart of the experimental procedure is reported in fig. 2 fig. 2. this diagram illustrates the methodology path implemented in this paper. td features were extracted from the filtered semg signals and fed to the selected learning models for estimating the gait phases. the hip angle was also fed to the pattern recognition models as well, as a fused feature space of the hip angle and the extracted myoelectric activity in the last experiment. actual gait phases as indicated by the dashed line were fed to the models only in training. b. pattern recognition models and experiments three learning models were employed to evaluate their capability to predict the gait phase during walking. knn with k=5 and svm model with radial basis function (rbf) kernel were applied to leverage its capabilities to capture the nonlinearities between the myoelectric information and the lower limb mechanical status [8]. in addition, a shallow artificial neural network (ann), composed of a single layer of 50 neurons, was also bench-marked against svm. given the experimental data structure, a 5-fold cross-validation scheme was employed for each subject, in which 80% is allocated for training and the remaining 20% is for testing to eliminate any potential overfitting of the implemented models rami mobarak al-khwarizmi engineering journal, vol. 20, no.2, p.p. 8693(2024) 89 [16]. firstly, two separate pattern recognition experiments were performed to evaluate the capability of the selected models to utilize the information carried solely either by the semg features of the thigh muscles or by the hip joint angle. furthermore, a last classification experiment was done to assess if fusing both the myoelectric and kinematic information can improve the estimation performance as done in [16] for the ankle angle regression task. c. evaluation metrics and statistics the confusion matrix was also computed to locally visualize the models' performance in each phase of the gait cycle. it's expressed as follows: 𝑪𝒐𝒏𝒇𝒖𝒔𝒊𝒐𝒏 𝒎𝒂𝒕𝒓𝒊𝒙 = [ 𝒙𝟏𝟏 𝒙𝟏𝟐 ⋯ 𝒙𝟏𝟓 𝒙𝟐𝟏 𝒙𝟐𝟐 ⋯ 𝒙𝟐𝟓 ⋮ ⋮ ⋱ ⋮ 𝒙𝟓𝟏 𝒙𝟓𝟐 ⋯ 𝒙𝟓𝟓 ] … (𝟐) 𝒙𝒊𝒋 = 𝑵𝒊𝒋 𝑵𝒊 × 𝟏𝟎𝟎% … (𝟑) where 𝑵𝒊 is the number of instances with actual class 𝒊 while 𝑵𝒊𝒋 is the number of instances predicted as class 𝒋 and belong to the actual class 𝒊. furthermore, for the overall evaluation of the pattern recognition experiments, three metrics were computed from each testing trial, i.e. accuracy, precision, and recall. the accuracy represents the number of correctly predicted samples from the entire classification decisions and is expressed in the following formula: 𝑨𝒄𝒄𝒖𝒓𝒂𝒄𝒚 = 𝑻𝑷 + 𝑻𝑵 𝑻𝑷 + 𝑭𝑷 + 𝑻𝑵 + 𝑭𝑵 … (𝟒) where 𝐓𝐏,  𝐓𝐍,  𝐅𝐏,  𝐚𝐧𝐝 𝐅𝐍 are the number of true positives, true negatives, false positives, and false negatives respectively. the precision and recall were computed to eliminate any misinterpretation that could be made by the accuracy due to class distribution imbalance especially since phases of gait have different durations. these are computed as follows: 𝑷𝒓𝒆𝒄𝒊𝒔𝒊𝒐𝒏 = 𝑻𝑷 𝑻𝑷 + 𝑭𝑷 … (𝟓) 𝑹𝒆𝒄𝒂𝒍𝒍 = 𝑻𝑷 𝑭𝑵 + 𝑻𝑷 … (𝟔) mann-whitney u-test was performed to assess the statistical significance of the achieved results to since it’s insensitive to data distribution. the significance level was set to 0.05, and bonferroni correction for multiple comparisons was applied to handle error rates of type i. a 𝒑𝒐𝒔𝒕 − 𝒉𝒐𝒄 statistical power analysis has confirmed the validity of results given the number of participating subjects with 100% statistical power. 3. results the three learning models (knn, ann, and svm respectively) provided the lowest accuracy in the case of considering only the semg features as input, with a classification accuracy of around 63% (fig. 3). the performance was improved when considering the hip angle time series as input to reach around 70% (fig. 3). however, a significant boost of the classification accuracy (p < 0.0001) was observed in the case of fusing the two input modalities for all the three models, reaching a maximum value of 85.48% when svm was employed (fig. 3). in terms of different models performances, ann and knn have shown comparable accuracy, while svm has demonstrated slightly higher performances in all the three input conditions. fig. 3. classification accuracy of the three classification models in the three different input conditions. the error bars indicate the standard deviations around the average accuracy. the asterisks **** refer to the significance threshold (p < 0.0001) rami mobarak al-khwarizmi engineering journal, vol. 20, no.2, p.p. 8693(2024) 90 the enhanced performances of fusing the hip angle and myoelectric data were further confirmed by the precision and recall values, as shown in table 1, where both metrics have reached up to 80%. however, the precision shows that the svm performance is not superior concerning the knn and ann in case of considering only the hip angle as input, and it drops to 48.27%, in contrast to what has been shown by the accuracy. in addition, both the precision and recall also contradict the accuracy. indeed, considering only the latter shows that the performances of the 3 models in case of considering only the myoelectric data as input are not lower than those purely driven by hip kinematics. this was further confirmed by the confusion matrix (fig. 4(b)), where the svm fed with hip angle mislabeled 91.51% of the actual tomwf phase as msf-mse and 75.75% of the actual hs-msf phase as mwf-to. these phases' extreme underestimations were not observed in the case of using only semg, as shown by fig. 4(a), where the off-diagonal terms have very low values. furthermore, the confusion matrix of the svm with fused input (fig. 4(c)) confirmed its boosted performances, as shown by the high classification accuracy that lies on the diagonal. table 1, precision and recall values of the three models in three different input conditions. a) b) c) fig. 4. panels (a), (b), and (c) are the confusion matrices for the svm model when fed by semg, hip angle, and fused condition respectively. the svm is considered here due to its superior performance. a heat map was used for accuracies between 50% and 100% for better visualization. precision (%) recall (%) emg hip fused emg hip fused knn 59.66 60.66 78.09 59.06 59.88 78.03 ann 57.72 56.94 78.25 57.23 59.28 78.89 svm 61.75 48.27 81.02 60.66 56.58 81.31 rami mobarak al-khwarizmi engineering journal, vol. 20, no.2, p.p. 8693(2024) 91 4. discussion this paper aims to exploit the possibility of predicting the gait phases during unconstrained walking using a minimal amount of myoelectric and kinematics information acquired exclusively from above the knee. this assessment extends the ankle angle regression approach proposed in [16] for pattern recognition, being potentially applicable for tf amputees. further, it could be suitable for different actuation needs and approaches, due to the inclusion of five subphases of the gait cycle, as in [22]. in particular, fig. 3 and table 1 show that fusing the hip angle with thigh myoelectric information provides consistent improvements (p < 0.0001) concerning using either one of these modalities separately in all the models, aligning with [16]. this improvement confirms that both signals carry complementary information for the estimation of the gait phases [11]. this finding is further validated by observing the confusion matrix (fig. 4(c)), where fused data information fed to the svm has demonstrated consistent high classification accuracy for the majority of gait phases. however, the lowest performance occurred for the hs-msf phase, which could be attributed to the similar activation profile adopted by sm, rf, and vm muscles at the beginning and the end of the gait cycle, as well as the similar hip joint angle values, since it’s in flexed position in the corresponding periods [26]. this is supported by the fact that 16.9%, 75.75%, and 17.01% of the actual first phase, i.e., hs-msf, were misclassified as the last phase (mwf-to) in the case of svm fed with myoelectric data, hip data, and fused data respectively (fig. 4). this suggests to look towards information sources that could behave distinctly solely at the beginning of the gait cycle. furthermore, regarding the comparison between the models' performance in the case of using either semg features or hip angle alone, the higher classification accuracy of the hip-based models indicated in fig. 3 could be misleading due to the class samples imbalance in the task of gait phase recognition because of the different durations of each subphase (fig. 1). this can be observed in their comparable performances shown by the precision and recall values (table 1), with superiority for the myoelectric information in case of svm, at values around 60%. these findings are further supported by confusion matrices in fig. 4(b), where a huge portion of the first and fourth gait phases were respectively mislabeled, as the fifth and second phases of the gait cycle. this could be imputed due to the quasi-symmetric shape of the hip angle profile in the sagittal plane around the middle of the gait cycle, which corresponds to the third phase in this case [26]. eventually, it is worth noticing that the proposed approach has shown high performances in estimating the gait phases during walking at a comfortable speed, in contrast to other studies where their approaches were tested on a treadmill or by using a constrained walking speed [27], [28]. in addition, these results appeared to be consistent in 40 subjects, which is higher than in other studies [11], [19], [29]. eventually, possible further improvements could involve the investigation of different postprocessing techniques or of adding other sources of information to boost the model's performance, especially in the hs-msf phase. it should be highlighted that although the proposed approach was evaluated using only td features, results motivate future studies to investigate if higher performances could be achieved in this motor task using other feature sets. this study has two main limitations that deserve to be declared. at first, the proposed approach was applied only in offline mode, thus motivating the development of a real-time interface to validate such a high-level control approach in prosthetic motion. in addition, the proposed method was validated only on walking subphases, thus suggesting the validation of this approach on phases of other locomotion modes as well as the transitions between these locomotions as suggested by the literature [6], [14]. 5. conclusion this study proposes a promising approach for gait sub-phase recognition during normal gait for tf amputees, by fusing a minimal amount of myoelectric and kinematics data captured exclusively from the proximal part of the lower limbs. the proposed method proved to be consistently robust in 40 subjects with recognition accuracy up to 85.48%, thus further supporting its potential applicability. the high estimation performance of several subphases of the gait cycle could offer flexibility for different actuation scenarios, depending on the prosthetic device's specifications as well as a smooth transition between the gait phases. therefore, the results of this study represent a step in the advancement of lower limb prosthetic control and rehabilitative exoskeletons, thus motivating future work to validate the proposed setup for different 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[29] t. liang, n. sun, q. wang, j. bu, l. li, y. chen, m. cao, j. ma, and t. liu, “semg-based end-to-end continues prediction of human knee joint angles using the tightly coupled convolutional transformer model,” ieee journal of biomedical and health informatics, 2023. this is an open access article under the cc by license : al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 21, no. 4, december, (2025), pp. 112 analytical and mechanical study of transtibial osseo-integrated prostheses implant saif m. abbas1*, jumaa s. chiad2, ayad m. takhakh3, kadhim k. resan4, abdullah ali sahib fatlawi5, and alaq saad h.t.j6 1,2,3,6 department of prosthetic and orthotic engineering, college of engineering, university of al-nahrain, baghdad, iraq 4 department of materials engineering, college of engineering, university of al-mustansiriyah, baghdad, iraq 5 specialist prosthetists and orthotists, head of orthotics and prosthetics department at sidra medicine and research center, state of qatar *corresponding author’s email: saif.mohammed@nahrainuniv.edu.iq (received 16 may 2025; revised 21 august 2025; accepted 15 september 2025; published 1 december 2025) https://doi.org/10.22153/kej.2025.09.005 abstract in amputation surgery, osseointegration is the placement of a metal implant in the residual bone and is conducted with an external prosthesis. in this study, the prospective application of ti–13nb–13zr alloy in a transtibial osseointegrated prosthesis was carefully examined. the alloy demonstrated favourable mechanical properties, such as strong mechanical strength with an average yield strength of 482 mpa, ultimate tensile strength of 551.843 mpa and modulus of elasticity of 74 gpa. in compression testing, the material showed its resilience to compressive loads, exhibiting 700 mpa yield strength and 1010 mpa compressive strength. the elastic modulus of ti–13nb–13zr alloy is approximately 55–65 gpa, which is much closer to that of human bone (10–30 gpa) compared with that of ti–6al–4v alloy (110 gpa). this proximity reduces stress shielding, a common issue in implants that a mismatch in stiffness between the implant and bone leads to bone resorption. analyses using the finite element method demonstrated uniform stress distribution, safety factors and minimal deformation for a range of implant sizes, guaranteeing structural integrity and functionality. the maximal von mises stress on the tibia bone and implant did not surpass the yield tensile stress of the titanium alloy and bone, which is 470 and 175 mpa, respectively; the maximum safety factor at l=120 and d=3 and the stress levels are not expected to induce material failure. these findings bring up new possibilities for enhanced prosthetic design and use in the field of biomedical engineering by demonstrating the alloy’s potential suitability for osseointegrated prosthetic applications. keywords: implants; osseointegration; prosthetics; bone attachment; ti–13nb–13zr alloy 1. introduction traditionally, prosthetic limb attachment has been accomplished by screwing the artificial limb into a socket that fits the stump. over the years, several developments in socket technology have improved the connection between the stump and socket. even with these advancements, this attachment method’s efficacy is usually considered lacking [1–3]. in developed nations, chronic vascular disease stands as the primary reason for limb loss [4]. nonetheless, many apparently healthy people also experience amputation because of trauma, neoplasia, infection and vascular embolism [5, 6]. the traditional method of attaching a prosthetic limb to the residual limb involves using a socket [7]. however, many socket prosthesis users report a worse quality of life [8–11] and have encountered problems such as dermatitis and infected sores. the inability of the residual limb’s soft tissues to mailto:saif.mohammed@nahrainuniv.edu.iq https://doi.org/10.22153/kej.2025.09.005 saif m. abbas al-khwarizmi engineering journal, vol. 21, no.4, pp. 112 (2025) 2 sufficiently sustain body weight leads to discomfort, degeneration and irritation of the soft tissues [12], as well as poor control over the prosthetic limb [10]. additionally, variations in stump volume caused by swelling exert an effect on the attachment [13, 14]. for the past 20 years, an alternative technique that entails affixing the prosthetic limb directly to the femur using a percutaneous implant has been proposed. the procedure that results in long-term repair is called osteointegration [15]. the goal of prosthetic bone anchoring is to reduce or eliminate the aforementioned issues. the principles of osseointegration, which has been employed to replace artificial teeth since 1965, serve as the foundation for our innovative approach [16]. a study found that after 15 years, the mandibular bone has a 90% implant survival rate [17]. for the external prosthesis to form a solid, long-lasting link, osteointegration necessitates direct contact between the fixture and bone tissue [18]. this strategy removes range-of-motion (rom) restrictions induced by sockets and skin conditions related to sockets, facilitates handling prostheses and improves limb control [19–21]. one possible remedy for bone-anchored prostheses would be to utilise a transcutaneous osseointegration implant [22]. currently, this method is used for patients who have had transfemoral amputations because of trauma or malignancies, but it may also be useful for patients who have peripheral vascular disease or transtibial amputations [23–25]. the impact of osseointegration implant surgery on functional performance and the risk of adverse events, particularly in specific patient groups, is not well supported by current data. despite the premise that bone-anchored prostheses aid in the early recovery of walking and movement, comprehensive research on the first year following therapy is lacking. prospective trials focused on amputees of the lower extremities who were having trouble using conventional socket-suspended prostheses and were thus candidates for press-fit osseointegration implants and preplanned rehabilitation regimens [26]. a metal implant is surgically inserted into the remaining bone of a severed limb on side to create bone-anchored prostheses, often referred to as osseointegrated lower limb prostheses. afterwards, a connection is used to attach this implant to an external prosthesis via a little skin incision on the opposite side of the stump. since may 5, 1990, when sweden implemented the first osseointegrated femoral prosthesis, several designs have been created [27]. six osseointegrated prosthesis designs are now available for purchase. every design has its own signals, advantages and disadvantages [28]. the osseointegrated prosthesis for the rehabilitation of amputees (opra) design is the most ancient osseointegrated prosthetic design and has the longest patient follow-up data available, having been developed over three decades [29]. this study uses ansys workbench 17.2 to numerically analyse the fatigue and mechanical characteristics of the suggested ti–13nb–13zr alloy as an implant inserted into the tibia bone for prosthetic osseointegration to improve fit (i.e. with regard to the volume and shape of tissue stump) and gait cycle; eliminate skin irritations due to friction, sweat or heat; and enhance quality of life and rom at sitting, standing or walking for patients. the elastic modulus of ti–13nb–13zr is approximately 55–65 gpa, which is much closer to that of human bone (10–30 gpa) compared with that of ti–6al– 4v (110 gpa). this closeness reduces stress shielding, a common issue in implants that a mismatch in stiffness between the implant and bone leads to bone resorption. 2. experimental procedures 2.1. material selection for the implant the cylindrical sections of the ti–13nb–13zr alloy according to astm f-1713:2008 [30] were provided with dimensions (l = 400 mm and d = 13 mm), as illustrated in fig. 1, to study tensile, compressive and fatigue properties, particularly to create standardised specimens for mechanical testing. the chemical composition of the ti–13nb– 13zr alloy used in the study is shown in table 1, which offers a thorough explanation of the alloy under investigation and demonstrates its appropriateness as an implant material. the chemical analysis was carried out via x-ray fluorescence testing at the material laboratory of the ministry of science and technology in baghdad, iraq. table 1, chemical composition (weight percent %) of alloy. elements wt. pct. % elements zr 14.23 zr nb 13.15 nb fe 0.1125 fe saif m. abbas al-khwarizmi engineering journal, vol. 21, no.4, pp. 112 (2025) 3 fig. 1. ti-13zr-13nb specimen (d=13, t=25) mm. 2.2. tensile test device the mechanical properties and tensile strength of materials used to create titanium alloy implants are evaluated using tensile test equipment, which is crucial for determining how long a material will last and how well it can withstand stretching stresses, as depicted in fig. 2. the astm e8/e8m [31] standard is primarily adopted to assess the properties of ti–13nb–13zr. this standard describes how to calculate tensile properties such as elongation, area reduction, yield strength and ultimate tensile strength. these qualities are essential to comprehending how the material behaves under strain. they shed light on its mechanical capabilities, robustness and applicability for a range of uses, such as implant material in prostheses, to determine if ti–13nb– 13zr is a viable material for implants, as demonstrated in fig. 3. fig. 2. test machine holds the specimen under tension. fig. 3. tensile test specimen and dimension in mm for metallic material 2.3. compression test device a compressive force is applied to a specimen between two jaws to assess its compressive strength, deformation characteristics and axial load tolerance, as shown in fig. 4. saif m. abbas al-khwarizmi engineering journal, vol. 21, no.4, pp. 112 (2025) 4 fig. 4. compression test machine. a static compression test was performed on a ti– 13nb–13zr specimen in compliance with astm e9-09 [32] criteria. the sample in this test was continuously traversed at a speed of 2 mm/min until it cracked or broke. three samples were subjected to this technique. figure 5 displays the specimen’s dimensions used for the compression test. fig. 5. the dimension of specimen (d=13, l=25) mm 2.4. fatigue test on a rotating ti–13nb– 13zr alloy specimen the typical method for performing a fatigue test on a rotating specimen composed of ti–13nb–13zr alloy is to apply repeated stresses to it cyclically, as shown in fig. 6. the fatigue life and durability of materials, especially those subjected to rotational stresses or forces, are commonly assessed through this type of test. such assessment provides crucial information for engineering and design by illuminating the extent to which a material can withstand the stresses caused by rotational motion over time. fig. 6. rotating fatigue device. swanson et al.’s study [33] provided a comprehensive dataset that was used to build the sn curve for human bone. with this specific testing protocol, samples are subjected to alternating compressive and tensile stresses to establish a relationship between the number of cycles (n) and stress (s), with the average stress for all cycles equal to zero. the results are necessary for analysis of tibia bone with implant via ansys software. fig. 7. the s-n curve of tibia bone [33] saif m. abbas al-khwarizmi engineering journal, vol. 21, no.4, pp. 112 (2025) 5 2.5. experimental evaluation of loads force plates were used to assess the gait cycle of the patient shown in fig. 8 during the test. the test aimed to assess the weights that the prosthetic limb experienced in different walking scenarios. the characteristics of the patient are as follows: 74 kg, male, 1.60 m tall, aged 30 and left amputation walking on a plate at the engineering department of prosthetics and orthotics. ethical approval was obtained from al-nahrain university’s college of engineering (02/2020). this information is meant to be utilised with finite element method (fem) software, such as ansys 17.2, to ascertain distribution of stress and deformation of the implant inserted into tibia bone and to comprehend how the prosthetic limb and the body interact as the patient walks. fig. 8. patient wearing below knee osseointegrated prosthesis 2.6. 3d modelling and fem model the model used in the below-knee amputation study was created using solidworks, a 3d parametric modelling programme widely used in engineering and design applications. the model is shown in fig. 9. fig 9. the model of the prosthetic implants. for the implant and bone depicted in fig. 10, the solidworks model enables the visualisation, analysis and customisation of the prosthetic design. this programme lets engineers and scientists precisely change the size of the implant, making sure it fits well, works with the body and is useful for patients who have had transtibial amputations. this strategy makes it possible to accurately alter and enhance the prosthetic design, improving its use and capacity to effectively meet the needs of each user. fig. 10. different length of implant with tibia bone this study examined the link between total deformation, safety factor and stress distribution via fem through numerical simulations of eight bone implantation situations. the implant cavities had varying internal diameters (3, 4, 5 and 6 mm) and lengths (195 and 120 mm), as shown in fig. 3. ansys workbench, a programme created by ansys (in version 17.2), was utilised. the implant and tibia bone were meshed with the help of ten node tetrahedral elements (solid187 type, fig. 11). these elements are commonly employed to discretise and approximate the geometry of solid structures in fem analysis. this analysis helps simulate and comprehend behaviours of stress and deformation in prosthetic systems. saif m. abbas al-khwarizmi engineering journal, vol. 21, no.4, pp. 112 (2025) 6 fig. 11. meshed model for the contact interactions between the prosthesis and the bone, eight-node surface-tosurface contact elements were employed. these contact elements, specifically targe170 and conta174, facilitated the simulation of the interactions between different model components. they enabled consideration of the contact behaviours and forces involved in the mechanical interaction and load transfer between the prosthesis and the bone. with consistent support in the implant and a force exerted from the patient’s weight at the proximal end of the tibia, fig. 12 illustrates how boundary restrictions affect the model’s analysis. these boundary conditions were essential for simulating and evaluating the behaviour and performance of the prosthetic system under specific loading and support scenarios. fig. 12. boundary condition of model 3. results and discussion 3.1. tensile property results for metallic material the mechanical properties determined in this study exhibit a characteristic curve that is typical, especially at the point at which 0.2% plastic deformation occurs. in accordance with astm standard requirements, the evaluated ti–13nb– 13zr alloy samples were subjected to static tensile testing. the findings indicate that the average yield strength is 482 mpa, ultimate tensile strength is 551.843 mpa and modulus of elasticity is 74 gpa, in comparison with those obtained by lee and bansal [34, 35]. table 2 and fig. 13 summarises these results and compares them with the astm f1713 standards and the supplier’s certificate. the feasibility of the material for biomedical engineering prosthetic applications must be evaluated through these comparisons. whether a material satisfies the mechanical requirements for use in biological prostheses can be determined by comparing it with standards and specifications. for the alloy in this study, it has low elastic modulus of approximately 55–65 gpa, which is much closer to that of human bone (10–30 gpa) compared with that of ti–6al–4v (110 gpa). this proximity reduces stress shielding, a common issue in implants that a mismatch in stiffness between the implant and bone induces bone resorption. table 2, mechanical properties of ti-13nb-13zr alloy. e gpa) σult (mpa) σy (mpa) sample 74 556.5 470.562 1 75 544.735 504.103 2 73 554.4 472.235 3 75 670 465 astm f1713[30] saif m. abbas al-khwarizmi engineering journal, vol. 21, no.4, pp. 112 (2025) 7 fig. 13. average stress-strain curve for implant. 3.2. compression property results the compression yield strength and compressive strength results are 713 and 470 mpa, respectively. the standard compression stress–strain curves in fig. 14 and table 3 illustrate the ti–13nb–13zr alloy’s remarkable ductility and robust strength. these characteristics are crucial for biomedical applications, especially for prosthetic components, which need materials that can support large weights without sacrificing their structural integrity. the ti– 13nb–13zr compression test is crucial for understanding the material’s response to compressive pressures during weight-bearing tasks, essential for osseointegrated prosthetic components. it confirms the material’s resistance to mechanical pressures, enhancing the efficacy, safety and compatibility of prosthetic implants with bone. table 3, compression and yield strength results. sample no. ϭult (mpa) ϭy (mpa) 1 714 470 2 716 472 3 708 469 average 712.6667 470.3333 taekyung lee [34] 720 475 fig. 14. stress-strain curve under compression. 3.3. fatigue property results for metallic material the tensions used in the fatigue testing ranged from 600 mpa to 250 mpa, and the test was conducted at room temperature. figure 15 shows the s–n curves obtained during the testing. the sample exhibited superior fatigue qualities in all tested scenarios, as shown by the tensile test results, corroborating the findings. a progressive degradation of the material’s fatigue resistance was indicated by the ti–13nb–13zr samples’ fatigue strength, which slowly declined as the number of failure cycles rose. this design is close to that in reference [36] and is crucial for evaluating the longevity and long-term usefulness of prosthetic components made of this material. understanding the material’s behaviour under cyclic loading and its capacity to withstand fatigue over time is essential for ensuring the continued functioning of prosthetic implants in real-world, long-term applications. fig. 15. s-n curve for metallic material. 3.4. gait cycle analysis (force plate) results the peak ground reaction forces at heel contact and toe-off are significant factors to consider. recognising any significant variations in the right and left legs’ characteristics is also important. clinicians and researchers can assess the loading conditions on the implant’s abutment and the functionality and stability of the implant during gait by examining the peak values of forces and moments during heel contact and toe-off. figure 16 shows the force–time curve, from which the maximum force is 600 n. saif m. abbas al-khwarizmi engineering journal, vol. 21, no.4, pp. 112 (2025) 8 fig. 16. ground reaction force vs. time for patient when walking on force plate. 3.5. fem analysis results as presented in figs. 17–19, the fem evaluations performed on prosthetic tibia implants with varying inner diameters and lengths reveal comparable stress distributions, total deformations and safety factors when the tibia bone and implant are fused. table 4 displays the results of the numerical analysis for each of the eight situations. table 4, the analysis of prosthetic tibias with various inner diameters and lengths dimension (mm) von-mises stress (mpa) safety factor total deformation (mm) l=120 d=3 46.648 7.0542 2.911 l=195 d=3 76.186 5.147 3.392 l=120 d=4 43.465 6.818 2.830 l=195 d=4 60.233 5.126 3.317 l=120 d=5 41.736 6.461 2.786 l=195 d=5 50.980 4.760 3.738 l=120 d=6 39.651 4.473 2.845 l=195 d=6 48.534 3.479 3.658 the abutment, which is usually the prosthesis component under the highest stress, demonstrated successful safety factors in all eight cases involving below-knee amputation implants, for which tibia implants were studied. the highest von mises stress values were recorded at l=195 mm. the von mises stress was maximal on the tibia bone, and the implant did not surpass the ultimate tensile stress of the titanium alloy, suggesting that these stress levels are not expected to cause material failure. given that the prosthetic implant’s maximal von mises stress is lower than the titanium alloy’s ultimate tensile stress, there is minimal risk of an abutment failing in this situation. these pressures do not cause the implant to break or sustain structural damage, allowing it to keep working. stress levels and the material’s resistance to deformation should be taken into account during implant design and analysis. through ensuring that stress levels stay below the ultimate tensile stress, the implant’s integrity and functionality are preserved. the purpose of this study’s assessment of a patient who had below-knee osseointegration was to measure limb stresses experimentally during critical walking periods. then, through fem studies, the behaviour of eight transtibial osseointegrated prosthetic cases was evaluated to assess probable implant or bone failures. the results of total deformation and fatigue factor of safety for the tibia with implant in this study agree with those from references [37–40]. fig. 17. fatigue factor of safety. fig. 18. total deformation saif m. abbas al-khwarizmi engineering journal, vol. 21, no.4, pp. 112 (2025) 9 fig. 19. equivalent stress (von mises) 4. conclusions material strength: the astm-certified ti– 13nb–13zr alloy demonstrated a strong mechanical strength, highlighting its potential for use in prosthetic applications. elastic modulus: the elastic modulus of ti– 13nb–13zr is approximately 55–65 gpa, which is much closer to that of human bone (10–30 gpa) compared with that of ti–6al–4v (110 gpa). this closeness reduces stress shielding, a common issue in implants that a mismatch in stiffness between the implant and bone leads to bone resorption. fem analysis: consistent stress distribution, safety factors and deformation were found using the fem over a range of implant sizes, guaranteeing dependability under various design conditions. because the maximal von mises stress on the tibia bone and implant did not surpass the yield tensile stress of the titanium alloy and bone, which is 470 and 175 mpa, respectively, the maximum safety factor at l=120 and d=3 and the stress levels are not expected to induce material failure. implant integrity: the tibia implant’s abutment showed minimal failure 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( 2025) 1-12، صفحة 4، العدد21مجلة الخوارزمي الهندسية المجلد سيف محمد عباس 12 الخصائص الميكانيكية وتحليل زرع األطراف الصناعية المتكاملة عظامياً عبر عظمة الساق ، 5، عبد هللا صاحب الفتالوي4، كاظم كامل رسن3، أياد مراد طخاخ2جياد، جمعة سلمان *1سسيف محمد عبا 6ألق سعد حسين 6،3،2،1 قسم هندسة األطراف والمساند الصناعية، كلية الهندسة، جامعة النهرين، بغداد، العراق 4 قسم هندسة المواد، كلية الهندسة، الجامعة المستنصرية، بغداد، العراق 5 قسم تقويم العظام واألطراف الصناعية، مركز السدرة للطب والبحوث، دولة قطر saif.mohammed@nahrainuniv.edu.iq البريد االلكتروني:* المستخلص إمكانية استخدام التكامل العظمي عبارة عن وضع غرسة معدنية في العظم المتبقي خالل الجراحة ويُستخدم مع طرف اصطناعي خارجي. دُرست بعناية السبيكة خصائص ميكانيكية ممتازة، مثل قوة ميكانيكية عالية ti-13nb-13zr سبيكة الظنبوب. أظهرت المدمجة عظميًا عبر في األطراف االصطناعية جيجا باسكال. ومن خالل اختبار 74ميجا باسكال، ومعامل مرونة يبلغ 551.843ميجا باسكال، وقوة شد قصوى تبلغ 482بمتوسط مقاومة خضوع يبلغ ميجا 1010ميجا باسكال وقوة ضغط تبلغ 700لمادة أيًضا مرونتها في تحمل األحمال االنضغاطية، حيث أظهرت مقاومة خضوع تبلغ الضغط، أظهرت ا جيجا 30-10ى عظام اإلنسان )جيجا باسكال تقريبًا، وهو أقرب بكثير إل 65و 55بين ti-13nb-13zr باسكال. يتراوح معامل المرونة المنخفض لسبائك جيجا باسكال(. هذا يُقلل من حجب اإلجهاد، وهي مشكلة شائعة في الغرسات، حيث يؤدي عدم تطابق صالبة 110) ti-6al-4v باسكال( مقارنةً بسبائك توزيعًا موحدًا لإلجهاد، وعوامل أمان، وتشوهات طفيفة (fem) الغرسة مع العظم إلى ارتشاف العظم. أظهرت التحليالت باستخدام طريقة العناصر المحدودة اتج عن لمجموعة من أحجام الغرسات، مما يضمن سالمة الهيكل ووظائفه. لم يتجاوز أقصى إجهاد فون ميزس على عظم الظنبوب والغرسة إجهاد الشد الن ، ومن غير l=120 d=3 توالي، وهو أقصى عامل أمان عندكال على الميجا باس 175ميجا باسكال و 470الخضوع لسبائك التيتانيوم والعظم، والذي يبلغ في مجال الهندسة المتوقع أن تُسبب مستويات اإلجهاد فشل المادة. تُتيح هذه النتائج إمكانيات جديدة لتصميم األطراف االصطناعية واستخدامها بشكل أفضل .الطبية الحيوية من خالل إثبات مالءمة السبائك المحتملة لتطبيقات األطراف االصطناعية الُمدمجة في العظم mailto:saif.mohammed@nahrainuniv.edu.iq this is an open access article under the cc by license : al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 21, no. 2, june (2025), pp. 53-71 development and implementation of an automated production line training system ali noori1*, faiz fawzi2, hussain tabina3, and egorov igor nikolaevich4 1,2department of automated manufacturing engineering, al-khwarizmi collage of engineering, university of baghdad, baghdad, iraq 3ministry of higher education and scientific research, baghdad, iraq 4vladimir state university, vladimir, russia corresponding author’s email: ali.nouri2204@kecbu.uobaghdad.edu.iq (received 16 may 2024; revised 9 january 2025; accepted 16 february 2025; published 1 june 2025) https://doi.org/10.22153/kej.2025.02.003 abstract industrial automation has significantly enhanced productivity, efficiency, and product quality by integrating advanced technologies such as robotics, artificial intelligence, and iot. this study focuses on rehabilitating and developing the dlms6000 automatic industrial production line training system at the ministry of higher education and scientific research in baghdad, iraq. the system, comprising six stations controlled by six plcs, had issues, including hardware failures, the need for periodic updates, and a lack of scada control. the development process replaced the six plcs with a single cymon plc and eliminated the need for cc-link network devices, reducing system complexity and cost. the system was optimized using a new control algorithm. the system achieved high precision, zero steady-state error, and a settling time of 40 ms by using the root locus method in the matlab program. additionally, a scada/hmi system was implemented to enhance control and monitoring. the newly developed system offers increased reliability, cost-efficiency, and ease of use, making it a suitable tool for educational purposes in university training rooms. keywords: automated production line; programmable logic controller (plc); training system; scada. 1. introduction over the past few years, industrial automation has been increasingly integrated into companies' work, increasing efficiency and productivity. industrial automation refers to utilizing control systems, machines, and information technology to automate traditional human tasks. this paradigm shift aims to simplify processes, increase efficiency, and improve product quality by integrating robotics, artificial intelligence, machine learning, and internet of things (iot) technologies[1]. control applications are deployed in automated industries through diverse hardware and software designs and methodologies. product categories, including computer numeric control (cnc), programmable logic controller (plc), and distributed control system (dcs), tackle specific issues and exhibit significant differences in programming and functionality. [2]. research and industrial practice pay attention to the training and support system for industrial workers, which addresses the growing complications of industrial machinery. skill or a procedure were taught in the training systems. these systems allow a person to become familiar with the process before training on the actual machine [3]. helal and yahya [4] study utilized humanmachine interfaces to regulate and oversee an automated line of production. the system utilized tia portal software for hmi creation, labview for data trending, and factory io for the design, simulation, and implementation of the production line. the s7-1200 plc controlled all functions, with ladder logic diagrams created by tia portal v13 software. the system permitted https://doi.org/10.22153/kej.2025.02.003 ali noori al-khwarizmi engineering journal, vol. 21, no.1, pp. 53-72 (2025) 54 dual human-machine interfaces for the control and monitoring of the pneumatic system's physical parameters. facilitating monitoring of equipment performance. the operationalized system can be used in laboratories to bridge the gap between theoretical understanding and practical implementation, fostering innovation and practical implementation. jingyu li. [5] designed automatic material sorting control systems using mitsubishi fx3u series plc controllers and vision sensors for training purposes. the platform combines various technologies, including vision sensors, electrical and electronic, mechanical, frequency converter, motor drive, and human-machine interface, to teach the detection, transmission, and processing processes. wan et al. [6] created a multifunctional sorting training platform using siemens s7-200 plc control. the platform consists of mechanical, electronics, electricals, microelectronics, sensors, interfaces, and signal transformation. it provides practical training experiences for teaching electromechanical integration. the platform uses modular thinking to make sorting modules more flexible, resulting in a greater educational effect compared to traditional training platforms. sasidhar et al. [7] developed a low-cost automation (lca) system that sorts objects based on their color using allen bradley micrologix 1200 plc controller. the system consists of two parts: software, which uses ladder logic programming to control processes, and hardware, which includes conveyor belts, sensors, an electronic system for sorting, and a motor. the automated sorting machine improves efficiency, practicality, and safety for operators, ensuring exceptional processing capacity and performance, particularly in color identification. additional functionalities include sorting operations based on dimensions, form, and mass, and simple sorting operations using a piston configuration. ye li. [8] developed a practice training system using plc programmable logic control, integrating mechanical and electrical laboratory equipment. the system includes a training platform, electromechanical integration equipment, plc modules, touch screens, and sensors. it helps students practice and simulate production, developing their brains and increasing their professional knowledge and skills. joanna baroro et al. [9] studied the replacement of manual packaging systems in the industry using a proposed automated system. the system uses a mitsubishi fx series programmable controller, sensors, motors, pneumatic components, and solenoid coils. experiments showed a 50-75% reduction in time spent at filling, weighing, and capping stations, and approximately 90% complete automation without human intervention. liang and xiao. [10] developed a practical training system to simulate automatic production lines using a siemens plc (s7-200). the system comprises sensors, switches, motors, lights, pneumatic elements, and mechanical frameworks. it encompasses mechanical concepts, pneumatic controls, detectors, electric control engineering, and programmable logic controllers. the system is open, providing students with a complete overview of internal wiring situations. it can be used in single-station systems or the entire system, and can be reconstructed according to innovation needs. the primary focus of the studies was on employing one or more programmable logic controllers (plcs) to manage various operations, including color detection, sorting, packaging, and handling. this was achieved by integrating expensive human-machine interface (hmi) software and touch panel screen packages with plcs provided by the plc manufacturer. a few research papers specifically addressed the control and monitoring of pneumatic systems utilizing scada systems. the motivation for this study is to rehabilitate and develop the automated industrial production line training system (dl-ms6000) in the ministry of higher education and scientific research / baghdad / iraq. the system comprises six stations (distribution, testing, processing, handling, assembly, and storing) used to simulate the production line. the system is controlled by six plcs (one for each station), and six network devices called cc-links that connect the six plcs to achieve a production line. this production line has technical problems in terms of the hardware, number of plcs (6 plcs), and network devices, which need a periodic costly update, which makes it unworking as a production line, and there is no scada system to control and monitor the production line. to develop this industrial line, reduce these problems, and facilitate control, maintenance, and operation, the cymon plc cpu cm1-cp4a plc regulates six production line training system stations. a pneumatic system drives the system, creating a scada system for control and monitoring. 2. the automated production line training system the automated production line training system (dl-ms6000) consists of six stations. the system is installed on an aluminum board with grooves, as shown in figure (1). all stations can be combined ali noori al-khwarizmi engineering journal, vol. 21, no.1, pp. 53-72 (2025) 55 easily to build an automatic product line. the stations consist of modular units that are easy to build, disassemble, and maintain. one mitsubishi plc controls each station. cc link is used as a network device to communicate and transfer data between the stations. the first three stations (distribution station, testing station, and processing station) will be discussed in this study. figure (2) illustrates the overall system block diagram. fig. 1. automated production line training system fig. 2. the overall system block diagram. 2.1 distribution station the distribution station is the first station, which plays a feeding role in supplying workpieces to the next station. it consists of two modules: a distribution module and a rotation transmission module. the distribution module can automatically deliver workpieces from the silo to the transfer stage so that the rotating cylinder can pick them up and transport them to another station. the distribution station is shown in figure (3). ali noori al-khwarizmi engineering journal, vol. 21, no.1, pp. 53-72 (2025) 56 fig. 3. the distribution module the rotation transmission module consists of a rotating cylinder, the vacuum generator, and suction cups combined, and the workpiece is transmitted from the distribution module to the next station. 2.2 testing station in this station, the testing process worked in two steps. the first step is testing the color (red, black, and silver) and material (plastic or metallic) of the workpiece, while the second step is to measure the height of the workpiece (high, low, or medium). the testing station has five parts: detection module, measuring module, rodless cylinder, defective loaded plunger, and swing module. the detection module consists of three types of sensors (inductive sensor, photoelectric sensor, and capacitance sensor), sensor tray, and workpiece launch cylinder, as illustrates in figure (4). the inductive sensor detects metal using the reflection principle; the capacitive sensor tests the existence of the workpiece, while the photoelectric sensor detects the color. fig. 4. the detection module judged the material type according to different combinations of detection signals. the material state is determined according to the signal from other parts of each sensor, as shown in table (1). ali noori al-khwarizmi engineering journal, vol. 21, no.1, pp. 53-72 (2025) 57 table 1, detection signals workpiece’s material sensor type black workpiece colored workpiece (black, red and silver) metal workpiece photoelectric sensor ○ ● ● capacitance sensor ● ● ● inductive sensor ○ ○ ● the measuring module consists of a height measuring device, analog sensor, and height measuring transfer cylinder, used to measure the height of the workpiece. the rodless cylinder is used to rise and down the testing platform, while the main role of the defective loaded plunger is to load the faulty workpieces. the swing module consists of a swing cylinder, a rise cylinder, and a vacuum sucker. the swing module works as a link to transport the workpiece between the testing station and the processing station. as shown in figure (5). fig. 5. testing station 2.3 processing station this station has three modules (turntable module, drill module, and hole detect module), as shown in figure (6). the turntable module consists of a dc gear motor, capacitive sensor, and inductive sensor. it has four workstations. the swing module draws the workpiece to the initial workstation. upon detection of the workpiece by the capacitive sensor, the turntable rotates 90 degrees, transferring the workpiece to the drilling module for the inner diameter drilling. subsequently, it is moved to the hole detection module workstation to ascertain its qualification before being sent to the fourth workstation. ali noori al-khwarizmi engineering journal, vol. 21, no.1, pp. 53-72 (2025) 58 fig 6. the processing station and the turntable module the drilling module consists of a dc motor and a double-acting cylinder; when the workpiece reaches the drill workstation, the cylinder moves down to start the drilling process, and then the turntable rotates 90 degrees to move the workpiece to the detection workstation. the hole detects module is a double-acting cylinder that works as a detection cylinder to judge whether the workpiece has a hole or not and to test the qualification of the inner hole. 3. undeveloped system the undeveloped production line training system has many problems: 1. high operating cost due to the need for continuous and expensive periodic updating of the connection devices. 2. using six plcs to control the system makes it a high-cost system. 3. the need for six connection devices (cc-link) to link the stations together to simulate the synchronous production line increases the system's cost. 4. the complex, huge, and closed-source software program used to operate the system is difficult for trainers to understand. 5. there is no scada system and the possibility of switching to manual operation and turning on and off the connection units may cause some interruptions and challenges in the system's work. 4. methodology to develop the system many steps are followed to rehabilitate and develop the automated production line training system, starting with diagnosing and discovering the system's problems and obstacles. after determining the main issue of the system, a new automatic control system was designed and implemented, using cymon plc cpu cm1cp4a plc to regulate six stations, which cancels the six plcs therefore, there is no need for using six connection devices (cc-link) to link the stations together to simulate the synchronous production line. building a new, simple, and smooth program with few steps makes the system less complex and more manageable for students and trainees to understand. cancel the manual operation option and create a scada system for control and monitoring. hardware and software components selected depend on the system functions and cost avoidance. 4.1 hardware development the major hardware elements that are utilized to execute the creation of the automated production line training system will be outlined in the following: 4.1.1 wiring system a new automatic control system was designed and implemented to control the whole automated production line training system using one programmable logic controller (plc), which needed to be made into a new wiring system, especially when most of the system's wires were damaged. the system uses 0.25mm control wires with 0.5mm terminals, which are compatible with the plc's i/o ports and the system terminals. figure (7) shows the new wiring diagram. ali noori al-khwarizmi engineering journal, vol. 21, no.1, pp. 53-72 (2025) 59 (a) (b) fig. 7. the wiring diagram. (a) inputs circuit, (b) outputs circuit 4.1.2 photoelectric sensor ben5m-mfr/ ben3m-pfr photoelectric sensor retroreflective type used in the first station instead of an optical sensor, which didn’t work properly; that gives the needed function and the economical price made this sensor perfect to use table 2, fiber-optic photoelectric and photoelectric sensor properties.[11], [12], [13], [14] sensor type fiber-optic photoelectric sensor e3x-a11 photoelectric sensor retroreflective ben5m-mfr amplifier high performance amplifier amplifier built-in type with universal voltage sensitivity adjustment 8 turn potentiometer adjustment vr sensing distance extended sensing distance 0.1 to 5m light source pulse-modulated red led (660 nm) infrared led (850nm) response time 200 µs max max. 20ms current consumption 35 ma max max. 4va working principle the sensor detects objects by transmitting or reflecting light, causing a change in light intensity. this signal intensity is processed and converted into a logic or electrical output. the photoelectric sensor consists of an led transmitter and a phototransistor, a solid-state semiconductor emitting light when electric current travels through it. the output signal changes based on object reflectivity. ali noori al-khwarizmi engineering journal, vol. 21, no.1, pp. 53-72 (2025) 60 4.1.3 capacitive proximity sensor: the capacitive proximity sensor kc1820kp2k replaces the capacitive proximity sensor cr18-8dn, which did not work. this sensor used in the testing station to detect the workpiece. because the sensing distance of the old sensor (cr18-8dn) was minimal (0 ~ 5.6mm), the sensor fixed to be so close to the workpiece to detect it, and when the swing module transport the workpiece between the testing station and the processing station the workpiece hit the sensor which caused a sensor failure, therefor replace the old sensor with a new model (kc1820-kp2k) with more considerable sensing distance (2 ~ 30mm) make it suitable to detect the workpiece with reasonable distance from the workpiece to protect the sensor from any friction with the swing module table 3, capacitive proximity sensor cr18-8dn and capacitive proximity sensor kc1820-kp2k properties.[15], [16], [17] sensor type capacitive proximity sensor cr18-8dn capacitive proximity sensor kc1820-kp2k sensing materials iron, metal, plastic, water, stone, wood etc. metal, plastic, water, oil sensitivity adjustment 15±3 -turn potentiometer (vr). 20-turn potentiometer (vr). sensing distance 0 ~ 5.6mm 2 ~ 30mm hysteresis max 20 % of sensing distance ≦ 10 % of sensing distance current consumption max. 15 ma ≦ 22 ma no-load working principle establishing an electric field by applying an alternating current (ac) voltage to a transmitting electrode detects the approach of an object or material by a slight change in capacitance value establishing an electric field by applying an alternating current (ac) voltage to a transmitting electrode detects the approach of an object or material by a slight change in capacitance value 4.1.4 programmable logic controller (plc) the automated production line training system had three mitsubishi fx2n-32mrccl plcs to control the system and three cc-links to link the stations to communicate. the main issue in this system was the cc-links, which needed periodic updates, it was expensive, to provide the necessary communication between the stations to simulate a production line. to solve this problem, the cymon cpu cm1-cp4a plc is used to control the whole system, and there is no need for communication or network devices. the mitsubishi fx2n-32mrccl plc has only 16 inputs and 16 output ports, and the system has more than 45 digital and analogue inputs and outputs; therefore, it cannot be used as a core controller. the cymon cpu cm1-cp4a plc controller provides flexibility and power to control various devices. the small design, adaptable setup, and robust instruction set render the cymon plc cpu cm1-cp4a an effective choice for system control. table 4, mitsubishi fx2n-32mrccl plc and cymon cpu cm1-cp4a plc specification. plc type mitsubishi fx2n-32mrccl cymon cpu cm1-cp4a operation method cyclic operation by stored program., performed by dedicated lsi stored program, cyclic operation, time driven interrupt i/o control method batch processing when end instruction is executed. i/0 refresh instructions available indirect, direct by instructions program language relay symbolic language + stepladder. sfc expression possible il (instruction list), ld (ladder diagram) data processing method 32 bit 16 bit counter up counter, up-down counter, high speed counter up counter, down counter, up-down counter, ring counter operation mode run, stop run, stop, pause, debug ali noori al-khwarizmi engineering journal, vol. 21, no.1, pp. 53-72 (2025) 61 4.2 the new automatic control system the new algorithm was built to perform the processes and system functions, as shown in figure (8). the cicon software managed all units of the automated production line, using ladder languish to build the program to perform the required actions for this project according to the algorithm. fig. 8. the flowchart of the first three stations. 4.3 system modelling of dc motor position of the turntable during the industrial line's operation and after completing the electrical wiring using one plc instead of six plcs, a problem appeared in the third stage. according to table (5), this problem is summed up by the fact that the turntable deviates with a different error rate while moving to the virtual location corresponding to the drilling process. table 5, error rate for the turntable location exp. no desired theta actual theta error rate 1 230° 272° 42° 2 230 274° 44° 3 230° 275° 45° 4 230° 275.8° 45.8° 5 230° 276.5° 46.5° the white paper was divided into 360-degree sections to represent the turntable's total angular movement and the dc motor's actual position during the automatic process, as shown in figure (9). fig. 9. turntable figure (10) depicts the electrical circuit counterpart of the armature with the free-body diagram (fbd) of the rotor. the transfer function is constructed using both components and assessed under no-load and full-load situations. ali noori al-khwarizmi engineering journal, vol. 21, no.1, pp. 53-72 (2025) 62 fig. 10. the electrical circuit counterpart of the armature with the free-body diagram (fbd) of the rotor. for this simulation, the subsequent values were assumed for the physical parameters appendix1 for dc motor series sg371 with spur gearbox, which is shown in figure (11). fig. 11. dc motor of the turntable hypothesized that the system's input is the voltage source (v) applied to the motor's armature, while the output is the shaft's position (theta). the rotor and shaft are presumed to be inflexible. a model of viscosity friction was proposed, in which the frictional force is directly proportional to the shaft angular speed. the torque generated by the dc motor is directly proportional to the current through the armature and the strength of the magnetic field. this magnetic field is assumed to be uniform in this context. thus, the motor force is directly correlated to the armature current by a factor that remains constant, as illustrated in the equation below. this is known as an armature-controlled motor. t = k * i …(1) k = the armature coil constant, i = the armature current. by using kirchhoff’s law v = l (di / dt) + r * i + e ...(2) l = inductance, r = resistance, e = back emf by applying laplace transform, i = (v k2 sθ) / (ls + r) …(3) also, t = j (θ ̈ ) + f (θ ̇) = k * i …(4) j = inertial torque, f = coefficient of friction. i = ((js^2 θ) +fsθ) / k1 …(5) by combining 3.3 & 3.5, θ / v = k /((ls + r)(js + f) + k_1*k_2 ) s …(6) k1 and k2 = constants the motor must be accurately aligned to guarantee that the steady-state error in its position is null when a designated position is specified. the steady-state error induced by a constant perturbation must also equal to (zero). the supplementary performance criterion is that the motor reaches its final position swiftly without considerable the overshoot. in this situation, the system must attain a settle time of 40 milliseconds and the overshoot of under 16%. simulating a reference input using a unit step input should provide the subsequent motor position output: • settling time below 0.04 seconds • do not exceed 16 per cent overshoot • no steady-state error arises, even when exposed to a step disturbance input. 4.3.1 the representation in matlab the transfer function: the motor's open-loop transfer function can be represented in matlab by defining the transfer function and the following parameters. executing the following script in the command line yields the output displayed below. ali noori al-khwarizmi engineering journal, vol. 21, no.1, pp. 53-72 (2025) 63 table 6, the parameters of the dc motor symple paremeter name value (j) moment of inertia of the rotor 9.6852 e-6 kg.m^2 (b) motor viscous friction constant 10.5231 e-6 n.m.s (kb) electromotive force constant 0.0822 v/rad/sec (kt) motor torque constant 0.0844 n.m/amp (r) electric resistance 15 ohm (l) electric resistance 8.25e-6h transfer function in continuous time: the controller will be developed using the root locus approach by converting an analog dc motor model, the sample data for the model of the dc motor can be obtained. the position of the dc motor open-loop transfer function in the laplace domain is as follows. furthermore, the design specifications of the 1radian stepped reference are as follows, as indicated on the main page. • the settling time within 40 milliseconds. • an overshoot below 16 percent. • no error in the steady-state occurs, even when subjected to a step disruption input. 4.3.2 developing a plant sampled-data model. the first step in designing a digital control system is to generate a sampled data model of the plant. therefore, choosing a frequency with which the continuous-time plant is sampled is necessary. in choosing a sampling period, it is desired that the sampling frequency be fast compared to the system's dynamics so that the sampled output of the system captures the system's full behavior so that significant inter-sample behavior is not missed. create a continuous-time model of the plant. create a new m-file and add the following matlab code (refer to the main problem for the details of getting these commands). running the m-file within the matlab command window will generate the below output. using the zpk command above transforms the transfer function into a form where the zeros, poles, and gain can be seen explicitly. examining the poles of the plant (or its frequency response), it is clear that the pole at -1.0287e+09 contributes very little to the plant's response. the gain crossover frequency of the plant is approximately 5 hz. therefore, choosing a sampling period of 0.001 seconds (frequency of 1000 hz) is significantly faster than the dynamics of the plant. this sampling period is also fast compared to the speed that will be achieved by the resultant closed-loop system. a sample time of 0.001 seconds is specifically 1/100 of the required time constant and 1/40 of the required settling time. the specified transfer function will be transformed from a continuous laplace domain into a discontinuous z-domain. the c2d command in matlab facilitates this translation, and it necessitates three parameters: • a model of a system. • the sample time (ts). • the hold circuit classification. assuming a zero-order hold (zoh) circuit, including the subsequent commands into the m-file and executing them in the matlab command window produces the sampled data model below. observe the presence of both the pole and the zero near z equal to zero, which effectively negates one another. the cancellation in the transfer function (tf) can be performed using the minreal command with an acceptable margin of 0.001. removing those poles and zeros will reduce the transfer function (tf) order and alleviate numerical difficulties in matlab. the utilization of the mineral command produces the resulting reduced transfer function order. note the absence of the pole and the zero at z equal to 0. analyse the system's closed-loop response without further compensation. initially, it must close the transfer function loop by employing the feedback instruction. the closed-loop response to steps was analysed utilizing the zero-order of hold technique after loop closure. this can be accomplished by using the steps and stairs instructions. when provided with a discrete model, the step command will produce a vector of discrete samples at the sampling time ts corresponding to the model. the following syntax indicates the simulation of the step response for 0.5 seconds. the steps command produces discrete data points in a stairstep manner, similar to the zero-order of hold circuit output. adding the following code to the last of the previous m-file and re-executing it generates a graph similar to the one illustrated below. ali noori al-khwarizmi engineering journal, vol. 21, no.1, pp. 53-72 (2025) 64 fig. 12. stair step response 4.3.3 root locus design the root locus methodology in design aims to adjust the closed-loop response by positioning the system's closed-loop poles at specified locations. this methodology applies to discrete-time models as well. the controller is designed using the control system designer graphical user interface (gui). initially, a window titled control system designer will open, displaying the form illustrated in figure (13). this window displays the root locus of the transfer function dp motor processed by the control system designer function. . fig. 13. the root locus of tf. in the control system designer, an integrator is incorporated into the compensator to mitigate the impact of a constant disturbance in a steady state. the integral control in continuous-time domains is denoted as 1 / s. the control system designer (csd) utilizes a forward variance estimation to transition from the s-plane for the z-plane, expressed as s equals (z-1) / ts, where ts denotes the sample time. including an integrator introduces a pole at one on the root locus diagram. the standard compensator format is the time constant form; however, the compensator will be formulated in zero/pole/gain form for this case. ali noori al-khwarizmi engineering journal, vol. 21, no.1, pp. 53-72 (2025) 65 fig. 14. adding compensating pole at z=1. the figure (14) illustrates a root-locus chart of a stable closed-loop system with three poles near 1, suggesting increased instability. a zero is added at one inside a unit circle to remove one of the poles and direct the inward of the root locus. the zero, located at z = 0.95, is included in the compensator in a manner analogous to that of the integrator. the real zero is selected from the context menu and positioned at 0.95 in the location cell. the root locus diagram should resemble that depicted in the figure (15). fig. 15. adding real zero at 0.95 real axis the integrator has improved disturbance rejection requirements; however, the closed-loop system may not achieve robust stability by additional adjustments to loop gain. additional design requirements remain unaddressed. to resolve these issues, ascertain the area of the complicated plane in which closed-loop poles have to be situated. incorporate these areas into the root locus by selecting the design requirement and configuring the overshoot to less than 16%. reiterate this procedure to incorporate the time to settle criterion under 40 milliseconds. the unshaded region identifies the closed-loop poles for transient requirements, assuming a canonical second-order system. ali noori al-khwarizmi engineering journal, vol. 21, no.1, pp. 53-72 (2025) 66 fig. 18. pole zeros compensator results figure (18) reveals that the root locus' two dominant branches don't pass through the desired region, requiring additional poles or zeros for the compensator to bend it. to cancel the zero at -0.98, add a pole nearby, as it adds overshoot into a step response. this will yield two branches from a root locus extending to the right and beyond the unit circle. two supplementary zeros can be incorporated near the desired closed-loop pole positions through the compensator editor window (cew) to augment the branches of a control system. a graphical tweaking methodology is employed in this instance. choose a solitary zero from the root locus editor (rle) tab, which is on the top of the control system designer (csd) window, and click the resultant "pointer" on the real axis to position the zero. reiterate the same procedure for the second zero. the effect of moving these two zeros can be visualized by moving the pointer over the corresponding zero on the root locus and clicking on it. an additional pole will need to be added to make the controller causal. using a graphical approach, an actual pole can be added by choosing an x from the root locus editor (rle) tab. through trial and error, the arrival was at a pole position of 0.6. the resulted root locus is shown below. fig. 19. try and error adding pole and zeros to move closed-loop pole positions along a root locus, a loop gain must be chosen. due to the noncanonical second-order closed-loop system, trial and error are necessary to identify pole locations. a plot for the closed-loop step response can help observe the effect of gain changes on the actual step response without relying on second-order idealization. ali noori al-khwarizmi engineering journal, vol. 21, no.1, pp. 53-72 (2025) 67 to check the system's closed-loop step response, navigate to the iotransfer_r2y: step tab. if closed accidentally, it can still be open. from the control system designer window, click on the new plot menu, select new step, and then choose iotransfer_r2y from the select responses to plot menu. the closed-loop step response will appear in figure (20). fig. 20. the closed-loop step response the step response plot with a loop gain of 1 meets the settling time requirement but not the overshoot requirement. to meet the overshoot requirement, the allowed step response shape is defined by choosing design requirements and setting the overshoot to 16% and the settling time to 0.040 seconds. a rise time must be less than 0.040 seconds. to modify the loop gain, a graphical tuning approach is used by dragging pink boxes on the root locus plot to place a closed-loop pole at a specified location. a loop gains of 800 reduces the overshoot to 10% and achieves a settling time of 0.02 seconds. the steady-state error goes to zero when no disturbance is present. the resulting step response plot is shown in figure (21). fig. 21. the resulting step response plot to verify the system's disturbance rejection properties, generate a disturbance response plot from the control system designer window or from the matlab command line. export the designed compensator in the control system designer to the workspace by clicking on the export button in the control system tab. select compensator c and click export. enter the following commands to produce the response plot shown in figure (22). fig. 22. the response plot. examination of the above shows that for a step disturbance, the steady-state error will still go to zero. employing the property of superposition, it is also apparent that the total response will have an overshoot of less than 16% and will reach a steady state well below the 40-millisecond requirement. ali noori al-khwarizmi engineering journal, vol. 21, no.1, pp. 53-72 (2025) 68 4.4 design and implementation of scada/hmi system the cicon software was employed to automate the production line and develop the scada/hmi system. the initial stage involved accessing the system's project (main ladder program) and incorporating the tags for all digital and analogue inputs, outputs, and timers. subsequently, the hmi tags were established and associated with plc tags. these tags facilitated the connection between hmi panels, sensors and actuators on the production line. the sensors and actuators were interfaced using plc i/o modules. the hmi display was engineered to accurately depict the real system. the hmi facilitated the visualization of the values produced during the process, as illustrated in figure (23). (a) (b) fig. 23. hmi in cimon (a) pneumatic hmi, (b) main hmi 5. results and discussion as a result, the realized system worked at high performance after the rehabilitation and development of the hardware components, enables one plc to control the automated production line training system without any network or communication device to link the stations, making it work consequently to simulate a real production line and reduce the cost of the system by cancelling the cc-links devices and 2 plcs by using one plc instead of three that means there is no need for the periodic update for the connection devices. building a new, simple, and smooth program with few steps makes the system less complex and easier for students and trainees to understand than the previous program used to control and manage this system. solved the problem that appeared in the third stage during the industrial line's operation that the turntable deviates with a different error rate while moving to the virtual location corresponding to the drilling process; the motor must be precisely positioned, with zero steady-state error and constant disturbance error, and achieve a settling time (ts) of 40 milliseconds and less than 16% overshoot. using the matlab program, the motor's openloop transfer function (tf) is represented. the controller was designed using the root locus method, converting an analogue dc motor model into a sample-data dc motor model based on the laplace domain transfer function. root locus methodology adjusts closed-loop response by ali noori al-khwarizmi engineering journal, vol. 21, no.1, pp. 53-72 (2025) 69 positioning poles at specified locations. this technique applies to discrete-time models and is designed using the control system designer gui. the loop gain is adjusted using a graphical tuning approach to meet the overshoot requirement by dragging pink boxes on the root locus plot; the loop gain is adjusted to place the closed-loop pole at a specified location. a loop gains of 800 decreases overrun to 10 per cent and attains a settling time (ts) to 0.02 s. the steady-state error is equal to zero in the absence of interruptions. research indicates that, after a step interruption, the steady-state error will ultimately diminish to zero. utilizing the principle of overlap, it is clear that the entire reaction will exhibit an overshoot of less than 16 per cent and will reach a steady state well below 0.04 second criterion. eliminate the manual operating option and develop a scada system for control and monitoring. the scada/hmi system was installed with cimon software, designed for constructing hmi interfaces and trends on the touch panel, thereby assisting the operator in controlling and monitoring the manufacturing line, as shown in figure (24). fig. 24. trends of height measure sensor and two photoelectric sensors. 6. conclusion the developed automatic production line training system can work very well with high accuracy without any downtime or malfunctions due to the problems with the wires, hoses, or the inefficiency of some sensors as were in the old system. that occurred because the entire system was developed, where the damaged hoses were replaced, in addition to implementing a new wiring system and replacing the old damaged wires. the production line can operate continuously, starting from the distribution process and ending with the last step after the inspection process in the processing station, after the control system has been replaced with a new system based on a cymon cpu cm1-cp4a plc to control the whole system instead of a plc in each station and without the need to link the plcs by using cc-links as network devices which help in overcoming the issue of the costly periodic update needed for the cc-links devices which reduced the total cost of the system by the cancellation of the other plcs and cc-link devices. the system works in perfect timing without any delay or deviation in the turntable of the processing station by designing a controller using the root locus (rl) method with a matlab program to achieve a settling time (ts) of 40 milliseconds and less than 16% overshoot with zero steady-state error and constant disturbance error made the motor stop precisely positioned in the drilling position. a new scada system has been created to control and monitor the automatic production line training system. the automatic production line training system can be applied in college and university training rooms because it is open, particularly the controlling cabinet. students can view the inner wiring overall, and the system is easy to understand. it can work under a single station or a whole system. ali noor al-khwarizmi engineering journal, vol. 21, no.1, pp. 53-71 (2025) 70 references [1] l. monostori, “cyber-physical production systems: roots, expectations and r&d challenges,” in procedia cirp, elsevier b.v., 2014, pp. 9–13. doi: 10.1016/j.procir.2014.03.115. 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( 2025) 71-53، صفحة 2، العدد12مجلة الخوارزمي الهندسية المجلد علي نوري 71 تطوير وتنفيذ نظام تدريب خط اإلنتاج اآللي 4إيجوروف إيجور نيكواليفيتشو ،3سين تبينة، ح2فائز فوزي ،*1علي نوري العراق ، بغداد، جامعة بغداد ، كلية الهندسة الخوارزمي المؤتمت، قسم هندسة التصنيع 1,2 العراق ، بغداد ، التعليم العالي والبحث العلمي وزارة 3 روسيا ، فالديمير ، جامعة فالديمير الحكومية 4 ali.nouri2204@kecbu.uobaghdad.edu.iq :البريد االلكتروني* المستخلص رنت األتمتة الصننناةية اتنتاجية والكءا ة وجودة المنتب بلننكي كبير مل دالج دمب التقنيام المتقدمة ملي الروبوتام وال كا االعننوناةي و نت حسنننتلقد في وزارة التعليم العالي والبحث dl-ms6000األشنننيا ر تركذ ه ل الدراسنننة ةلة ةادة تتهيي وتووير نراب تدريإل دا اتنتاا الصنننناةي األوتوماتيكي مل ملنكالم، بما العلمي في بغداد، العراقر كان النراب، ال ي يتتلف مل سنت محوام يتم التحكم فيها بواسنوة سنتة وحدام تحكم منوقية قابلة للبرم ة، يعاني وقية القابلة للبرم ة السننننتة ر اسننننتبدلت ةملية التووير وحدام التحكم المنscadaفي ذلك أةواج األجهذة والحاجة لة تحديلام دورية ونقص التحكم في ، ممنا قلني مل تعقيند النرناب وتكلءتن ر تم تحسننننيل cc-linkوأزالنت الحناجنة لة أجهذة شننننبكنة cymonبوحندة تحكم منوقينة قنابلنة للبرم نة واحندة مل نو في root locusمللي ثانية باسنتخداب رريقة 40النراب باسنتخداب دوارزمية تحكم جديدةر حق النراب دقة ةالية ودوت حالة مسنتقرة عنءريوا ووقت اسنتقرار ر حديلنوا مذيدوا مل الموثوقينة والءعنالينة scada/hmiر باتضننننافة لة ذلك، تم تنءين نرناب matlabبرنامب لتعذيذ التحكم والمراقبنةر يقندب النرناب المووح غرف التدريإل ال امعيةرمل حيث التكلءة وسهولة االستخداب، مما ي عل أداة مناسبة لألغراض التعليمية في this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 20, no. 3, september, (2024), p.p. 51-58 a proposed control algorithm for automated storage and retrieval system ali r. hameed* and osamah f. abdulateef ** *,** automated manufacturing engineering department, al-khwarizmi college of engineering, university of baghdad, baghdad, iraq *email: ali_mfcstd@kecbu.uobaghdad.edu.iq (corresponding author) **email: drosamah@kecbu.uobaghdad.edu.iq (received 30 may 2023; revised 30 august 2023; accepted 28 september 2023; published 1 september 2024) https://doi.org/10.22153/kej.2024.09.002 abstract this paper introduces an algorithm that enhances open-loop stepper motor motion systems. the objective is to close the loop with fewer hardware requirements, increasing flexibility in speed and weight capacity for storage and retrieval (s/r) machines and reducing cost. the method involves integrating the algorithm into a distributed control system, minimizing hardware, processing power, and maintenance shutdowns. the results highlight the algorithm’s effectiveness. adjusting torque/speed parameters mitigates motor stalling in s/r machines successfully, leading to improved efficiency. unlike commercial s/r machines, this revolutionizes closed-loop stepper systems, making them more efficient, relatively cost-effective as well as practical for educational purposes. keywords: asrs; s/r machine; automated storage system; closed-loop control; stepper motors; single deep 1. introduction automation plays an important role in the development of an industrial society [1]. different types of automation systems have been utilized in the industrial sector, indicating the handiness and the ability to improve the different manufacturing processes as stated in [2-4]. one of the most common applications that utilize different automation techniques is the storage and retrieval machine [5]. a storage and retrieval machine (s/r) is one that performs the action of transporting goods between pre-defined locations (storage keeping units,) inside a multi-storage system or between storage locations and unloading/loading areas. the instructions for these actions are given by a human through a certain interface or smart storage management system [6]. automated storage systems are widely used in many applications, including warehouses, stores, ports and pharmacies [6]. many benefits can be obtained from the automation of as/rs systems, such as savings in terms of labour costs and floor space, the ease and the speed of handling items and improved throughput level[7]. some trends to accomplish this system have been documented in the literature. these trends include the main drawbacks registered in the system, which are the high initial cost and low flexibility in terms of layout and size as stated in [8]. this system is also considered a complex system in terms of management and design considerations for safety, durability, throughput and robustness. applications of s/r machines must have closed-loop motion systems that prevent any damage that may be caused by an external effector or overweight object, system fault or cumulative position error. in these cases, severe damage may also be caused to the system’s mechanism, and the carried part may be affected, resulting in losses in maintenance cost and shutdown times [9,10]. many studies have focused on the control of automated storage and retrieval systems. for example, ekren et al. [11] suggested an analytical file:///c:/users/iraq/desktop/ali_mfcstd@kecbu.uobaghdad.edu.iq mailto:drosamah@kecbu.uobaghdad.edu.iq https://doi.org/10.22153/kej.2024.09.002 ali r. hameed al-khwarizmi engineering journal, vol. 20, no.3, p.p. 5158(2024) 52 model for first-in-first-out-based scheduling rules to calculate the mean and variation of shuttle and elevator running times and assess storage system performance. wang et al. [12] presented a mathematical model for time sequences based on the movement traits of shuttles and elevators. the shuttle and elevator task scheduling problem is converted into an assembly line parallel job problem to create the scheduling task queue model within the given time frame through the study of the mathematical model. the job scheduling problem’s multi-objective optimization function is also solved using the pareto optimization approach based on an elitist, non-dominated sorting genetic algorithm. yang et al. [13] examined access and placement allocation scheduling problems for products. two related models (integer programming model and dynamic programming model) are used to address this issue to maximize the operational efficiency of the system. in a similar as/rs, yang et al. [14] used a hybrid genetic algorithm-based on polychromatic sets theory to resolve the scheduling issue of storage and retrieval. the results of the trials demonstrate that this hybrid genetic algorithm has certain benefits in dealing with the scheduling issue of storage and retrieval. this hybrid approach considerably decreases the computing time needed to identify the running path in addition to reducing cycle times. yan et al. [15] introduce a multiobjective scheduling optimization model for multiaisle as/rs systems, improving upon previous models. they presents an innovative nsabc algorithm, combining nsga-ii and abc techniques, with customized solution methods. extensive testing shows that nsabc outperforms other algorithms in as/rs scheduling optimization. kang [16] focuses on optimizing an autonomous vehicle-based storage and retrieval system with transfer robots in automated warehouses. the goal is to reduce reshuffling, which occurs when a retrieved bin is deep in a stack, by planning an efficient order-picking sequence. rather than exhaustively exploring all possible sequences, the study introduces a greedy algorithm that provides a heuristic solution. alnahhal et al. [17] examine the effect of the input/output area location on asrs total travel time and suggest a two-step preparation strategy. they verified their work using a simulation model, which resulted in an enhancement of throughput by 21% to 28%, depending on storage height and order quantity. ecem et al. [18] studied the flexible travel of autonomous mobile robots (amrs) and developed intelligent deadlock and collision prevention algorithms on agent-based modelling that amr agents can make smart decisions when interacting, resulting in improvement of up to 39% in the storage system flexibility compared to a nonflexible design. this paper introduces a closed-loop algorithm designed to enhance the load capacity versatility of the s/r machines. the algorithm achieves this by automatically determining speed and acceleration levels, effectively addressing the issue of stalling and guaranteeing the attainment of the desired position. the primary focus of the algorithm lies in optimizing the y-axis controller, given its significant load-bearing role in the transportation of goods between storage racks and the loading/unloading area. 2. proposed control algorithm the proposed algorithm is applied on a single deep s/r machine, which depends on three cartesian axes, x, y and z (horizontal, vertical and depth, respectively), as shown in fig. 1. fig. 1. s/r machine prototype. the designed as/rs system efficiently converts the rotational motion of three motors into precise linear movements along the x, y and z axes, enabling seamless material retrieval, relocation, and storage based on specific data inputs. for rapid x and z-axis movements, the system relies on belt pulley mechanisms, while the y-axis, prioritizing precision and load-lifting strength, employs a lead screw mechanism. the as/rs system has compact dimensions of 1000 x ali r. hameed al-khwarizmi engineering journal, vol. 20, no.3, p.p. 5158(2024) 53 1000 x 500 mm, making it highly portable and space efficient. the frames of the as/rs system are constructed using carbon steel, ensuring durability and stability, while the cart frame utilizes lightweight aluminium to enhance its mobility. a distributed control system (dcs) is utilized in which a separated microcontroller is used to control each of the axes because of the slow processing capabilities of the controllers used. the vertical movement is done by a nema 23 bipolar hybrid stepper motor with 3.6n.m holding torque. the voltage supplied is 48-volt dc and draws 3.5 amp per phase. the motor is indirectly coupled with a timing belt to a leadscrew-nut mechanism. during the operation of the machine, the stepper motor may stall (i.e. synchronization is lost between the motors’ rotor and stator by one step or more) when lifting a higher weight (i.e. goods) with a specific set speed. the algorithm can deal with a range of goods weights without an identification process either manually or measuring it using weight sensors in which the algorithm automatically adjusts the speed and acceleration along with the item weight to alter motor torque/speed output as needed according to the following equation: 𝑃 = 𝑇 × 𝜔 where 𝜔 = 𝜋 30 ∙ 𝑛 , where p is mechanical power, ω is the angular frequency of the motor shaft and n is the rotational speed of the motor’s rotor. the algorithm engages the controller which is responsible for controlling the actuators (i.e., motion axis) and receives instructions and feedback axis current states to a main controller. the overall process of the s/r machine used in this article is illustrated in fig. 2. first, the process initialises by obtaining input from a graphic user interface (gui) application. next, it transfers the coordinates of the target position to the xand yaxes controller via a usb interface, then the actuators start to move towards the target. finally, when the target is reached, the controllers returns feedback to the gui to begin the pick or drop process. a gui was written using c-sharp programming language in which the parameter of the desired storage keeping unit (sku)) has been set and the required process involved has occurred as shown in fig. 3. fig. 2. s/r machine overall process flow. the position of the desired sku was identified, in which each sku has its own (x-y) position and item depth (z coordinate). each sub-controller for the x-y axis has its own control path to attain the required level and is demonstrated in fig. 4. after receiving the required position from the main controller, the sub-controller starts calculating the required speed, acceleration and number of pulses to reach the setpoint. the number of pulses required (np) is calculated according to the following formula: 𝑛𝑝 = 𝑛𝑠𝑥𝑟𝑔 𝑝 , where ns represents the number of pulses per revolution of the motor, x is the relative linear position required, is the gear ratio or the number of motor turns for every single turn of the screw and p is the pitch of the screw. feedback information for the carriage position is fed through a buffer circuit attached to a quadrature encoder. a ali r. hameed al-khwarizmi engineering journal, vol. 20, no.3, p.p. 5158(2024) 54 pulse train of the calculated parameters is fed to the stepper driver through which the stepper starts to rotate accordingly while the encoder captures the motion and the buffer keeps updating the real position value while the sub controller updates the error between the target and real position to compensate the error by generating control signals according to the error until it is eliminated. fig. 3. graphic user interface for the s/r machine fig. 4. control path of the proposed system. the algorithm requires a series of sequential steps. initially, data, which include information regarding the desired position, are collated. subsequently, the microcontroller commences calculating the required number of pulses and compares the collected data with the current reference position. the positional error obtained from the feedback signal (shown in fig. 5-a) is then determined as the disparity between the calculated pulses and the initial position. the pulses that represent the error are subsequently transmitted to the stepper driver as shown in fig. 5-b. the generated pulse frequency determines the motor revolutions per minute (rpm), and a higher frequency leads to a higher rpm. the rate at which the frequency changes represent the motor acceleration. speed is divided into four zones, each with a certain speed different from the others. the first zone operates with a speed of 350 rpm and an acceleration of 500 rev/min2 and can lift 0.8kg of goods. the second zone has a speed of 320 rpm and an acceleration of 250 rev/min2 and can handle up to 2kg. the third zone works in 190 rpm and an acceleration 100 rev/min2 and can handle up to 3.75kg . the last zone has the slowest speed of 100 rpm and an acceleration of 50 rev/min2 and can handle up to 7.5kg. the algorithm designed to shift the working zone automatically depending on the error in position measured by the encoder buffer circuit. when the error exceeds half the value of the required target position after the first motion command fails to reach the target, the zone is shifted to the next zone and a new command is sent. the shifting process continues until the target direction pulse train quadrature encoder buffer counte r µcontroller calculates:  error  speed  acceleratio stepper driver stepper motor carriage position position pulse target position ali r. hameed al-khwarizmi engineering journal, vol. 20, no.3, p.p. 5158(2024) 55 position is reached. in case the target is not obtained after the fourth zone because the weight exceeds the limit or due to mechanical malfunction, the algorithm feedback alarm signals the main controller to stop the process and solve the problem. 3. results and discussion the proposed algorithm provides a low-cost solution for the stalling issue that occurs when loading a stepper motor with a higher weight at a specific speed. in real applications, this machine may deal with a range of goods with different weights, and speed is negatively proposed to the output torque. the algorithm solved this issue automatically without the need to add a weight sensor or adjust the speed of the motor manually. the positional error successfully indicates the stall when it occurs. fig. 5. voltage-time signals for a motion command captured with a digital analyzer, (a) feedback from encoder (b) calculated pulse train. the algorithm was applied to the vertical axis y to transport different goods weights (0.4 to 7.5 kg) from the loading/unloading area to three randomly chosen skus ( 3,5, and 8). the storage layout is shown in fig. 6. fig. 6. layout of the storage racks used for obtaining results for the current algorithm. the path of motion to reach sku 3 with a 5-kg payload is shown in fig.7 as an example. the sku height is the red line, and the path shows the sequence to drop (a) and pick (b) an item for the store and retrieve operations. the results are shown in table 1. a specific colour was designated for each zone: pink, blue, yellow and green correspond to zones 1 to 4, respectively. the weights being transported are listed in the left column, while the time taken for each weight to be delivered to the various skus is recorded in the remaining three columns. the transport time for sku 8 is short compared to sku 5 and 3 because of the relatively short vertical distance. the effect of weight change does not appear to be significant because the distance is too short to allow the stepper to reach the maximum speed of the current zone. thus, it does not need to proceed to the next zone because of acceleration, the same result is supposed to appear in all skus with the same storage level. ali r. hameed al-khwarizmi engineering journal, vol. 20, no.3, p.p. 5158(2024) 56 table 1, experimental results of different weights being transformed from loading/unloading unit to sku 3, 5 and 8 with zones and consumed time. object weight (kg) the time interval for sku 8 (sec) the time interval for sku 5 (sec) the time interval for sku 3 (sec) 0.4 10.58 14 20 0.8 12.36 18.23 22.8 0.9 12.41 18.5 22.9 1.2 12.89 18.72 23.4 2 13.22 18.89 24.2 2.5 13.52 18.92 24.8 3.75 15.2 19.2 28.5 5 16.1 19.4 32.8 6.25 16.8 23.55 34.8 7.5 18.2 32 38.2 for sku 5 and 3, the effect of the weight appears to be significant because the motor reaches the maximum speed of the current zone, causing the stall to occur. thus, the algorithm proceeds to the next zone with less speed and more torque along with the associated weight range and completes the task successfully. the disadvantage of this algorithm is represented as an instability in the storage system throughput because of the change in goods weight that becomes obvious when comparing the time consumed to transport different goods weight for the same sku. fig. 7. motion path to reach sku 3 in a) store, b) retrieve cycles. 4. conclusion different goods weights are transported between storage racks in most applications of the s/r machines. thus, an open loop stepper motor system that drives the linear axis of the machine is exposed to stall during speed increase at the beginning of motion, particularly when carrying weight at certain speeds that exceed the feasible region of the torque speed curve of the stepper motor. these stalls may cause severe damage to the machine mechanism and increase system downtime. the proposed algorithm addressed the issue automatically without a weight sensor. it successfully prevented the effect by closing the loop with a position sensor and manipulating the working speed and acceleration of the stepper as needed rather than fixing their values and dividing them into four zones. therefore, the proposed algorithm has the ability to handle a range of weights without stalling. this algorithm can be applied to any application that uses a stepper motor and the best zones with the appropriate hardware size and permissible load range. however, this method affects the throughput prediction of the as/rs because the weight is changed. ali r. hameed al-khwarizmi engineering journal, vol. 20, no.3, p.p. 5158(2024) 57 5. reference [1] s. s. khaleel, m. y. salloom, and a. m. shammari, "arduino-based controller for sequence 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[18] e. e. turhanlar, b. y. ekren, and t. lerher, "autonomous mobile robot travel under deadlock and collision prevention algorithms by agent-based modelling in warehouses," international journal of logistics research and applications, pp. 1-20, 2022 https://doi:10.15587/1729-4061.2020.202184 https://doi:10.15587/1729-4061.2020.202184 (2024) 51-58، صفحة 3، العدد20مجلة الخوارزمي الهندسية المجلدعلي رشاد 58 سيطرة مقترحة لمنظومة الخزن واالسترداد المؤتمتةخوارزمية علي رشاد*، اسامة فاضل عبد اللطيف** *،**قسم هندسة التصنيع المؤتمت/ كلية الهندسة الخوارزمي/ جامعة بغداد/ العراق ali_mfcstd@kecbu.uobaghdad.edu.iq*البريد االلكتروني: drosamah@kecbu.uobaghdad.edu.iq**البريد االلكتروني: المستخلص ق من خالل اغال لمفتوحةاتقدم هذه الورقة البحثية خوارزمية مبتكرة تهدف الى تحسين أداء نظام حركة المحرك ذو الخطوات الذي يعمل بنظام الحلقة ها ألجهزة بلمسموح الحلقة باستخدام أجهزة ذات كلفة معقولة، تحقق الخوارزمية المقترحة مستوى اعلى من المرونة من حيث السرعة ومدى االوزان ا المستخدم. من خالل ، حيث تعمل وحدات تحكم متعددة معا لتلبية متطلبات(dcs)الخزن/االسترداد. تم تصميم الخوارزمية للعمل ضمن نظام تحكم موزع ن حيث خدام وفعال ماالست هلتقليل متطلبات األجهزة وقوة المعالجة والتوقف المحتمل بسبب األعطال و تكاليف الصيانة. توفر الخوارزمية المقترحة حال س آلت الطاقة في ا استهالكالتكلفة. باإلضافة الى ذلك تعالج الخوارزمية النسبة بين عزم الدوران/ السرعة للتعويض عن مشاكل الوزن الزائد المحتملة و ركة ذات مل أنظمة الحعي طريقة بإمكانية احداث ثورة فالخزن/االسترداد وبالتالي تحسين كفاءتها االجمالية. بفضل ميزاتها الفريدة، تتمتع هذه الخوارزمية .المحركات ذات الخطوات التي تعمل بنظام الحلقة المفتوحة، مما يجعلها اكثر كفاءة وفعالية من حيث التكلفة file:///c:/users/iraq/desktop/ali_mfcstd@kecbu.uobaghdad.edu.iq mailto:drosamah@kecbu.uobaghdad.edu.iq 1. introduction 2. proposed control algorithm 3. results and discussion 4. conclusion 5. reference this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818-1171, issn (online): 2312-0789 vol. 21, no. 1, march (2025), pp. 35–48 secure and lightweight cipher for resource-constrained iot healthcare applications using snake key generation saja kareem ismael1*, mohamed ibrahim shujaa1 and ahmed bahaaulddin a. alwahhab2 1electrical engineering technical college, middle technical university, baghdad, iraq 2technical college of management, middle technical university, baghdad, iraq *corresponding author’s email: bbc0071@mtu.edu.iq (received 22 june 2024; revised 24 august 2024; accepted 23 september 2024; published 1 march 2025) https://doi.org/10.22153/kej.2025.09.002 abstract the integration of the internet of things (iot) in healthcare has transformed the monitoring of physiological parameters, significantly enhancing the capabilities of medical diagnostics and patient care. this study explores the use of advanced cryptographic techniques to secure iot healthcare systems, particularly through block chain (bc) technology. moreover, this study evaluates the effectiveness of two cryptographic key generators—bee swarm key generator and snake key generator—in enhancing data security within a bc-based framework for remote patient monitoring. our study conducts a series of nist randomness tests to compare the performance of these key generators in terms of randomness, resilience to cryptographic attacks and computational efficiency. results show that the snake key generator outperforms the bee swarm key generator, demonstrating higher randomness in key generation and better secure coverage of the orientation space. this finding is crucial for securing important healthcare data, especially given the complexity of iot devices, which transmit vital patient health information. furthermore, this study examines the double-layer encryption architecture used to secure data in at rest and during transmission from a sensor’s gathering location to long-term storage. this approach is essential to preserve the privacy and integrity of patient data, which is critical for maintaining trust in iot healthcare systems. this study aims to provide a comprehensive and comparative analysis to support the continued evolution of secure, efficient and scalable cryptographic solutions within iot healthcare, demonstrating the importance of selecting the most effective key generation technique to address the unique security challenges of this new field. keywords: iot healthcare; blockchain technology; cryptographic key generation; data security; nist randomness 1. introduction an internet of things (iot) variant integrates the human body with numerous sensor-equipped devices to measure various physiological parameters and create a set of linked iot entities that are analysed by decision-support algorithms to forecast health-related results [1-4]. iot technologies improve disease diagnosis and patient activity monitoring through biosensors that assess environmental and physiological conditions, enabling physicians to make informed medical decisions. patients’ wearable gadgets are the focus of patient-specific and customised nutrition care, with data security playing a crucial role. security in remote patient monitoring systems involves the use of secure methods to encrypt patient information, transmit data through secure channels and limit access. privacy and data integrity issues can be addressed through the implementation of a block chain (bc) as it creates a decentralised ledger to enhance electronic health records (ehrs) [5]. the authors proposed and implemented a bc framework, which focuses on the aspects of remote patient monitoring and data management, in another paper to support iot healthcare [5]. privacy issues arise from access control measures [6], whilst the application of bc in healthcare ensures patient data mailto:bbc0071@mtu.edu.iq https://doi.org/10.22153/kej.2025.09.002 saja kareem ismael al-khwarizmi engineering journal, vol. 21, no.1, pp. 3548 (2025) 36 integrity in remote treatment procedures [7]. ieee32-bit bcz is recommended as a defense layer for transporting health records at the sensor level of internet of medical things (iomt), protecting the data packets sent from the sensor to the receiver [8]. this study evaluates the effectiveness of the bee swarm key generator and compares it to the snake key generator used to secure bc-based lpwmns for rpm to mitigate the attack risks and add security layers within each block to protect data privacy [9]. the goal of this study is to develop a reliable system for accurately measuring and monitoring vital patient metrics whilst enhancing healthcare system security through an innovative bc approach. this approach involves using either the bee swarm or snake key generator, each offering different levels of encryption security. the key generator must ensure the protection of sensitive data by incorporating measures to anonymise identities linked to each bc block to further safeguard patient privacy. this comparative analysis aims to determine an effective cryptographic key generator for securing healthcare data within an iot framework [10]. this study introduces a new two-layer encryption architecture designed for iot healthcare applications, utilising the bee swarm key generator and the speck cipher to protect patient data from initial capture to prolonged storage. this dual encryption strategy ensures utmost confidentiality and security of patient information, validated through several nist randomness tests that confirm the unpredictability and robustness of the cryptographic techniques used. the key contributions of this study are as follows:  development of a robust framework for iot healthcare: ensuring the secure confinement of critical medical data and maintaining data integrity during sensor data transmission;  enhancement of bc security within the public ledger: anonymising sensor data before cloud storage using lightweight block encryption, acting as a privacy and confidentiality filter, thereby maintaining the anonymity of the block’s owner;  introduction of an innovative secure random key generator inspired by bee swarm behaviour: this generator significantly enhances the randomness and security of cryptographic keys, drawing parallels with snake optimisation (so) techniques to further optimise key generation processes;  hybrid key generation approach using bee swarm algorithms and so techniques: this method constructs secure and random cryptographic keys leveraging the innate efficiency of bee swarm structures and the effective adaptability of snake optimisation, ensuring robust security measures for iot healthcare data transmission and storage. 2. related work current iot-related medical research focuses on disease identification, patient health status and medication administration whilst ensuring information privacy in patient records. ogundokun et al. [11] proposed a crypto-stegno method for protecting healthcare data in iot, which effectively prevents data leakage. however, this method lacks the integration of bc learning parameters. abdellatif et al. [12] advocated for the development of an emergency response and remote monitoring bc solution with secure non-harmonised vital sign data transmission; however, it struggles with cybersecurity challenges. pandey et al. [13] proposed a healthcare cybersecurity architecture based on bc, deep belief networks (dbn) and residual networks (resnet) for disease detection and classification. veeramakali et al. [14] presented a cryptographic iot security authentication scheme based on optimal homomorphic encryption (ohe) and a deep learning neural network (dnn) for data encryption. abd el-latif et al. [15] proposed a novel secure e-healthcare architecture based on bc, utilising the orthogonal particle swarm optimisation (opso) for concealed transmission and the optimised dnn (odnn) for disease classification. quantum computer threats are emphasised for bc’s role in cybersecurity, whilst quantum walks are considered for fresh cryptographic algorithms. cao et al. [16] proposed an authentication and encryption system based on the qiwq for bc data transfer. ciphers developed by shankar et al. [17] featured a bc-based ico for cybersecurity, leveraging the random neural network model and unique encryption. mathews et al. [18] introduced an enhanced two arch2 solution, which claimed to be more scalable than the existing one and closer to achieving bc time in the optimisation of model metrics. 3. iot ecosystem the iot framework allows for the integration of smart devices—such as mobile phones, sensor devices and raspberry pi—into a network that senses, monitors and responds to various environmental stimuli. the goal is to expand saja kareem ismael al-khwarizmi engineering journal, vol. 21, no.1, pp. 3548 (2025) 37 connectivity by simultaneously linking multiple devices to the internet [20,21,22]. this connectivity enables human-to-machine and machine-tomachine interactions. for instance, humans can engage with machines to conduct medical procedures, remotely monitor patients at home and monitor real-time conditions within hospital infrastructure [23,24,25,26,27]. moreover, machines can autonomously exchange data, with sensors, for example, relaying information to a cloudlet system for temporary data storage [28, 29]. a representative model of an iot-enabled healthcare system is illustrated in fig. 1. fig. 1. iot and its associated healthcare platform the architecture of a traditional iot-enabled healthcare system consists of four fundamental components. the first component is the hospital environment, which serves as a hub for healthcare providers and accommodates inpatients and outpatients [30, 31]. iot technologies enable hospital administrators to effectively track the health and recovery of outpatients in their homes through real-time monitoring. this monitoring is facilitated by wearable or embedded medical body sensors that collect data, which are then processed and interpreted into actionable insights using machine learning algorithms and specialised software. this setup aids medical personnel in remotely assessing the current health conditions of outpatients [32]. meanwhile, outpatients who are no longer under intensive monitoring, or those who have recuperated, are equipped with iot-enabled ambient assistive living devices. these devices help individuals in independently managing their health by providing real-time feedback on various health metrics, such as caloric expenditure, blood sugar levels and heart rate. consequently, individuals are highly equipped to proactively address potential health issues with the information supplied by these iot devices. this proactive health management enhances overall patient welfare and equips caregivers with the essential data and tools required for delivering high-quality health services to the public, an approach commonly referred to as smart healthcare. 4. block chain block chain (bc), an innovation with multiple uses, is now considered a mainstay in healthcare. bc can be described as a linked chain of embedded data blocks with records that have been made secure through the use of cryptographic hash algorithms [33]. every peer in the decentralised system has a copy of the bc and acts according to a consensus mechanism, increasing the system’s reliability and capability for continuous operation [34-36]. bc applications ensure the safety of medical records, the supply chain of drugs and the secure transfer of ehrs. the bc components, such as cryptography, immutability and decentralisation, enhance the security levels by making data modification without permission difficult [37-38]. nevertheless, cyber threats are not foreign to bc; vulnerabilities persist, making cryptographic methods essential [39]. electronic health records, once stored in digital format, now have a safer, distributed home in blockbased chains [40]. he is achieved through the collective effort of funding authorities, medical researchers and health departments. some bc use cases face unique risks and constraints, such as 51% attacks, where miners controlling more than half of the network’s hash power can alter the bc. the suggested resistance measures include optimising hash rates, proper monitoring of mining pools and evaluating proof of work (pow) consensus algorithms [41]. phishing attempts deceive users into divulging secure login information; the immediate protective measures include increasing browser security, using anti-malware and avoiding suspicious links. routing attacks involve intercepting data transmitted to internet service providers; thus, safe routing protocols, data encryption and strong passwords are essential to prevent such attacks. although signing with keys is important, they can still be forged, making the protection of private keys crucial [41]. insecure perimeters of bc networks can collect user credentials, highlighting the importance of prohibiting the storage of bc keys in plain text and regularly reviewing system access. therefore, this extensive literature review on bc security in the healthcare context underscores the necessity for further enhancement of protected health information [42]. saja kareem ismael al-khwarizmi engineering journal, vol. 21, no.1, pp. 3548 (2025) 38 fig. 2. general representation of the structure of a bc 5. iot security the real world consists of numerous physical objects connected through the iot environment, necessitating encryption to protect against eavesdropping for clique, chip id and chip integrity and authenticity. data collected in the sensor node itself must be protected, and firewall and ids are crucial to protect data in the intermediate networks from the internet to the wsn [43]. most iots are resource-constrained, making a single approach to security impractical. aes and des are not feasible to implement in iot devices because they require numerous gates and a high-power consumption [43]. lightweight cryptography is suitable for iot devices partly due to the low quantities of ram or rom/flash for storage, processing capability and shorter clock cycles. lightweight ciphers can be categorise based on software or hardware implementation. software implementation offer low cost and flexibility. daemen et al. asserted that the key features of an effective lightweight cipher are memory efficiency, resource efficiency, security strength, low implementation complexity and high throughput with short processing time. the model should efficiently work with minimal memory requirements, effectively perform on lowpower devices. moreover, the model should consume minimal energy to prevent battery drain during use. these ciphers should provide security against linear, differential and other attacks, such as biclique, zero correlation, mitm and algebraic attacks. considering such requirements and security considerations, lightweight ciphers are appropriate for securing communication in constrained environments [43]. 5.1. speck cryptography speck is a lightweight block cipher used in the cryptographic field, designed by the united states national security agency and publicly released in 2013 june, belongs to this family. speck shows flexibility concerning key and block sizes, featuring an arx design (fig. 3). moreover, speck has several variations, including speck32/64, speck48/72 and speck64/128, where the first number represents the block size in bits, and the second denotes the key size in bits. in the configuration shown in fig. 3, the cipher is referred to as speck2n/wn, where 2n represents the block size in bits, and wn denotes the key size in bits. speck’s underlying round function involves right rotations of n-bit words and their addition:) the operations are bitwise xor, modular addition and left and right circular shift. together, these operations form an efficient and secure cipher for resource-constrained, power-efficient environments [44]. fig. 3. speck round function 5.2. bee swarm optimiser bee swarm optimisation (bso) [45] refers to an optimisation algorithm, as it is a nature-inspired optimisation algorithm that simulates the foraging saja kareem ismael al-khwarizmi engineering journal, vol. 21, no.1, pp. 3548 (2025) 39 behaviour of honey bees. bso uses the collective intelligence and swarm behaviour of bees to determine optimal solutions for complicated algorithms. the bso algorithm is divided into two principal search phases: exploration and exploitation. in the exploration phase, scout bees search for new food sources (possible solutions to the problem in the problem space) by running in a random-by-choice way. during the exploitation phase, working bees exploit the most successful feeding sites, improving the quality of the solutions. furthermore, the honeybees act as onlookers, evaluating the shared food sources of foragers and stochastically selecting which to further exploit. this mechanism allows the search process to dynamically balance exploration in new-candidate areas and exploitation of the best solutions. given that bso has been successful on a variety of optimisation challenges, such as engineering design, scheduling and machine learning, it can converge to high-quality solutions and maintains diversity throughout the swarm. bso is a novel nature-inspired algorithm that has gained significant attention in recent years for key generation in cryptographic applications, mainly due to its ability to provide robustness and efficiency. strong, random keys are essential for ensuring security and protecting systems from cryptographic attacks. furthermore, bso can efficiently search across a large search space and converge towards optimal solutions, making it well-matched for this. during the exploration phase, the algorithm evaluates a wide range of potential keys, significantly enhancing their randomness and unpredictability. in the exploitation phase, these potential keys are fine-tined to ensure that they are cryptographically strong and complex. research has shown that bsos achieve better randomness in key generation and produce more secure keys than traditional key generation methods, which is an important factor when considering the sensitive data that can be accessed and the threats of cybercrime. the versatility of bso also makes it highly adaptable for customisation to various cryptographic protocols and demands, positioning it as an effective and competitive cryptographic key generator [45]. pseudocode for bee swarm optimiser 1. initialise the population of scout bees with random solutions. 2. evaluate the fitness of each scout bee. 3. whilst the stopping criterion is not met, do: for each employed bee, do: 1. select a solution from the neighbourhood of the current solution. 2. evaluate the fitness of the new solution. if the new solution is better than the current solution, then: 1. replace the current solution with the new solution. 2. for each onlooker bee, do: 1. select an employed bee based on the fitness probability. 2. select a solution from the neighbourhood of the selected employed bee’s solution. 3. evaluate the fitness of the new solution. 4. if the new solution is better than the selected employed bee’s solution, then: 1. replace the selected employed bee’s solution with the new solution. 2. for each scout bee, do: 3. if the solution has not improved for a certain number of iterations, then: replace the solution with a new random solution. memorise the best solution found so far. 4. end whilst 5. return the best solution 5.3. snake optimisation snake optimisation (so) [46] is a matinginspired algorithm that algorithm simulates the common behaviours of snakes in searching for food and competing for mating. mating occurs in subchilled areas, where food is available, but the temperature is considerably low. the algorithm has two main phases: exploration and exploitation. in the search state, snakes randomly forage for food during non-mating periods, mimicking their behaviour in the wild when food is scarce. this process involves generating a random population and dividing it into males and females. during the exploitation phase, snakes approach food when it is abundant, and many engage in mating or competing for mates if the climate permits. this process updates the positions of snakes based on food availability and temperature, selecting the best solutions for each snake. the algorithm balances exploration and exploitation through snake behaviour, where food quantity and temperature in each cell determine their movements. the so algorithm initialises the generation of its random populations (step 1) and evenly dividing it into males and females. food quantity and temperature influence snake behaviour. when food is scarce, snakes engage in exploration, randomly searching for food. when food is abundant, snakes saja kareem ismael al-khwarizmi engineering journal, vol. 21, no.1, pp. 3548 (2025) 40 move towards it. if the conditions permit, snakes either compete for mates or engage in mating. the algorithm updates positions based on these phases, using equations to model the movement and behaviour of snakes. the effectiveness of the so algorithm was tested on benchmark functions from cec 2017, where it outperformed several state-ofthe-art algorithms in terms of average results and standard deviation. this algorithm maintained a good balance between exploration and exploitation, demonstrating its effectiveness in solving optimisation problems. additionally, the so algorithm was tested on cec 2020 functions, showing strong performance against other competitive algorithms. the results highlighted the algorithm’s capability to adapt to various conditions and achieve high rankings across different functions. the effectiveness of the so algorithm in key generation for cryptographic systems lies in its robust exploration and exploitation mechanisms. inspired by snake behaviour, the algorithm thoroughly searches a wide range of possible keys (exploration) and refines the best candidates (exploitation). this approach ensures that the generated keys are highly random and secure, minimising the predictability and making them difficult to guess or brute-force. the so algorithm’s ability to balance these phases allows it to efficiently handle large search spaces, producing cryptographic keys that meet highsecurity standards. overall, the comprehensive search strategy and high-quality solution refinement make the so algorithm a powerful tool for secure key generation [46]. algorithm: so for key generation 1. initialise problem setting a. define the dimensions (dim) of the problem. b. set the upper bound (ub) and lower bound (lb) of the search space. c. set the population size (pop_size) and maximum number of iterations (max_iter). 2. randomly initialise the population d. for each individual i in the population: i. xi = xmin + rand() * (xmax − xmin) 3. divide population n into two equal groups: males (nm) and females (nf) e. nm ≈ n / 2 f. nf = n − nm 4. whilst (current iteration 𝑡 ≤ 𝑀𝑎𝑥_𝐼𝑡𝑒𝑟) do g. evaluate each group nm and nf h. find the best male (𝑓𝑏𝑒𝑠𝑡, 𝑚) and best female (𝑓𝑏𝑒𝑠𝑡, 𝑓) i. define temperature (𝑇𝑒𝑚𝑝) using 𝑇𝑒𝑚𝑝 = 𝑒𝑥𝑝(−𝑡 / 𝑇) j. define food 𝑄𝑢𝑎𝑛𝑡𝑖𝑡𝑦 (𝑄)𝑢𝑠𝑖𝑛𝑔 𝑄 = 0.5 ∗ 𝑒𝑥𝑝((𝑡 − 𝑇) / 𝑇) 5. if (𝑄 < 0.25), then // exploration phase (no food) k. for each male xi,m: i. 𝑋𝑖, 𝑚(𝑡 + 1) = 𝑋𝑟𝑎𝑛𝑑, 𝑚(𝑡) ± 0.05 ∗ 𝐴𝑚 ∗ ((𝑋𝑚𝑎𝑥 − 𝑋𝑚𝑖𝑛) ∗ 𝑟𝑎𝑛𝑑() + 𝑋𝑚𝑖𝑛) ii. 𝐴𝑚 = 𝑒𝑥𝑝(−𝑓𝑟𝑎𝑛𝑑, 𝑚 / 𝑓𝑖, 𝑚) 6. for each female xi,f: iii. 𝑋𝑖, 𝑓(𝑡 + 1) = 𝑋𝑟𝑎𝑛𝑑, 𝑓(𝑡) ± 0.05 ∗ 𝐴𝑓 ∗ ((𝑋𝑚𝑎𝑥 − 𝑋𝑚𝑖𝑛) ∗ 𝑟𝑎𝑛𝑑() + 𝑋𝑚𝑖𝑛) iv. af = exp(−frand,f / fi,f) 7. else if (q > 0.6), then // exploitation phase (food exists) 8. for each individual xi,j (male or female): 𝑋𝑖, 𝑗(𝑡 + 1) = 𝑋𝑓𝑜𝑜𝑑 ± 2 ∗ 𝑇𝑒𝑚𝑝 ∗ 𝑟𝑎𝑛𝑑() ∗ (𝑋𝑓𝑜𝑜𝑑 − 𝑋𝑖, 𝑗(𝑡)) else // mating or fighting mode 1. if (rand() > 0.6), then // fight mode 2. for each male xi,m: 3.xi,m(t + 1) = xi,m(t) + 2 * fm * rand() * (q * xbest,f − xi,m(t)) 4.fm = exp(−fbest,f / fi) i. for each female xi,f: 5.xi,f(t + 1) = xi,f(t + 1) + 2 * ff * rand() * (q * xbest,m − xi,f(t + 1)) 6. ff = exp(−fbest,m / fi) l. else // mating mode v. for each male xi,m: 7. xi,m(t + 1) = xi,m(t) + 2 * mm * rand() * (q * xi,f(t) − xi,m(t)) 8. mm = exp (−fi,f / fi,m) ii. for each female xi,f: 9. xi,f(t + 1) = xi,f(t) + 2 * mf * rand() * (q * xi,m(t) − xi,f(t)) 10. mf = exp(−fi,m / fi,f) m. if egg hatches, then replace the worst male and female: i. xworst,m = xmin + rand() * (xmax − xmin) ii. xworst,f = xmin + rand() * (xmax − xmin) 11. check the termination condition a. if t > max_iter, then terminate the process. 12. return the best solution found. 6. proposed methodology the proposed methodology (fig. 4) aims to address the security challenges in iot healthcare systems by integrating a robust dual-layer encryption architecture. this architecture utilises the bee swarm key generator and speck cipher to secure patient data saja kareem ismael al-khwarizmi engineering journal, vol. 21, no.1, pp. 3548 (2025) 41 from initial capture to prolonged storage. the primary focus is to ensure utmost confidentiality and security of patient information, validated through several nist randomness tests that confirm the unpredictability and robustness of the cryptographic techniques utilised. the methodology consists of real-time monitoring of different physiological parameters through intelligent sensors linked to iot, including oxygen, temperature and pulse oximeter sensors. the sensors collect a bunch of critical patient data, which are then transmitted to a raspberry pi. the raspberry pi serves as the primary node for data aggregation and preliminary processing. iot sensor-level encryption using the speck algorithm is used to encrypt the collected information to protect vulnerable healthcare data. immediate encryption ensures that data sent by a sensor are securely communicated to a receiver, keeping all data safe from man-in-the-middle attacks and maintaining continuous privacy standards. thereafter, these data are transmitted to the cloud, encrypted for safety and stored, making it available for healthcare providers when needed. one of the key features of this proposed methodology is promoting the security and integrity of the stored data through bc technology. this mechanism uses a decentralised ledger based on the bc framework to provide durable data storage. patient data are stored on a bc keychain, ensuring an additional level of data privacy encryption within each block. the research compares the effectiveness of two cryptographic key generation methods: the bee swarm key generation and the snake key generation, evaluating their efficiency and robustness in securing bc-based remote patient monitoring systems. fig. 4. proposed scheme the concept of the mesoscale swarm key generator is inspired by the swarm behaviour of bees, which enhances randomness and strengthens the security of the crypto keys used. this generator is matched with the so method, which works for key generation processes using the strategic flexibility of snake motion. the integration of these two methods aim to generate highly secure and random cryptographic keys, protecting iot healthcare data communications and data-at-rest from unauthorised disclosure, thereby preventing privacy concern or breaches under applicable rules or regulations. the methodology involves reinforcing access control to unify access permissions between sets of patients or families to enhance patients’ and families’ ownership of their data. this approach reduces the burden of access management, alleviates concerns about data leaks and prevents data from becoming obsolete due to malpractice. the approach suggests that each sensor data must be encrypted using lightweight block encryption and brought to the cloud as an anonymised version maintain confidentiality. this function serves as a privacy and confidentiality filter, ensuring that block ownership remains anonymous. saja kareem ismael al-khwarizmi engineering journal, vol. 21, no.1, pp. 3548 (2025) 42 the goal of the study is to develop a robust and secure framework for gathering patient data, guaranteeing precise measurement and monitoring and improving healthcare delivery security by implementing a cutting-edge bc program. this dual-layer encryption, in addition to the new secure random key generator, is expected to significantly improve the security of patient data in an iot healthcare environment. 7. experimental results this section presents the results of testing the bee swarm key generator and snake key generator, both designed to enhance the security of bc-based remote patient monitoring systems. the experimental analysis had different themes, dealing with different sections of cryptographic security, including randomness, resistance to cryptographic attacks and computational efficiency. the results obtained from table 1 show that both key generators passed the nist randomness tests. however, the snake key generator proved to be significantly faster in tests assessing resistance to modern cryptanalysis and computational efficiency. this generator demonstrated strong randomness properties, as demonstrated by the frequency (monotonicity) test and cumulative sums test, which resulted in the snake key generator producing unpredictably generated keys, unlike the bee swarm key generator. the resilience of some of these keys to various cryptographic attacks confirms that the snake key generator produced keys with significant resilience to key recovering attacks. these keys can effectively thwart numerous common varieties of attacks, including most types of brute force and cryptographic hash function attacks. this aspect is essential, especially when handling health data, as patient information must be securely managed and protected. the snake key generation is also computationally efficient, exhibiting the lowest computational cost amongst the three whilst ensuring security. this efficiency is an ideal fit for iot scenarios, where resources are scarce, and processing power is highly valuable. in summary, the key generators from the bee swarm and the snake present no practical flaws in terms of encryption safety. however, when comparing both, snake key generator outperforms in randomness, attack resilience and computational efficiency. the bc technology in question is considered the best fit for healthcare applications, encompassing nursing, telemonitoring, and patientcentric healthcare apps. this effectiveness lies in the technology’s ability to encrypt health data in accordance with the necessary security and regulatory standards. table 1, nist randomness test results for speck cipher (bee swarm vs snake) the nist randomness test results (table 2) for the speck cipher, after optimisation with the bee swarm and snake algorithms, provide significant insights into the performance and reliability of these cryptographic methods under different conditions. the tests focus on various aspects of randomness, a crucial factor in determining the effectiveness of cryptographic ciphers. in the frequency (monobit) test and the frequency test within a block, both algorithms demonstrated random results with the speck cipher, even though the p-values were higher for the bee swarm optimisation (approximately 0.65) compared with those after so (around 0.42 and 0.48, respectively). this result suggests that both optimisers can maintain randomness, with the bee swarm showing slightly higher randomness in these particular tests. the runs test, which assesses the randomness of sequences produced by the cipher, presented a stark contrast between the two. the speck cipher optimised with the bee swarm yielded a p-value snake optimiser bee swarm test number and name p-value conclusion p-value conclusion frequency (monobit) test 0.3587953578869416 random 0.2888443663464849 random frequency test within a block 0.3587953578869416 random 0.2888443663464849 random discrete fourier transform (spectral) test 0.24690699562474117 random 0.7456027889274623 random non-overlapping template matching test 0.9999999999999729 random 0.9999999556775546 random approximate entropy test 1.0 random 1.0 random cumulative sums test (forward) 0.5998890627269671 random 0.5754947715401479 random saja kareem ismael al-khwarizmi engineering journal, vol. 21, no.1, pp. 3548 (2025) 43 indicative of randomness (0.064), whereas the snake optimiser resulted in a p-value of 0.0, suggesting non-randomness and potential vulnerabilities in generating random sequences under the snake optimisation. in the discrete fourier transform (spectral) test, both optimisers produced random outcomes, although the bee swarm’s p-value of 0.305 suggests a more robust randomness compared with the snake’s lower p-value of 0.014. this result indicates a marginal but potentially significant difference in handling frequency components within the encrypted outputs. the non-overlapping template matching test showed both algorithms yielding highly random pvalues, virtually indistinguishable from each other and close to one. this notion implies that both methods are highly effective in ensuring randomness in this aspect, with negligible differences between them. the cumulative sums tests (forward and backward) also demonstrated excellent performance for both algorithms, with p-values at or near the threshold. however, the results post-so edged slightly closer to perfect randomness, indicating strong performance in ensuring that the sum of sequential random variables does not significantly deviate from the expected behaviours. overall, although the bee swarm and snake optimisers effectively enhance the randomness of the speck cipher in several tests, the snake optimiser shows particular strengths in the cumulative sums tests. however, the snake optimiser also exhibits a critical weakness in the runs test, suggesting an area where the bee swarm optimiser maintains superior performance. this mixed result highlights the nuanced performance differences between these two optimisation techniques when applied to cryptographic key generation, underscoring the need for careful selection based on specific security requirements. in fig. 5, the image displays a user interface for a firebase realtime database project titled ‘saja333444’. this database is designed for storing and managing iot results. the database entry for ‘patient id: 56’ includes various attributes, such as. the first and last names, room temperature, body temperature, spo2 level and heartbeat rate. these numerical values correspond to patient health parameters that are monitored on a real-time basis. the entry also contains fields, such as ‘current hash’ and ‘previous hash,’ which are be used for data integrity or versioning. the dashboard provides a unified, real-time, single point of view of the data acquired from the iot devices and presents an integrated approach to healthcare monitoring technologies and cloud-based data management. fig. 5. real-time database saja kareem ismael al-khwarizmi engineering journal, vol. 21, no.1, pp. 3548 (2025) 44 table 2, comparison with related work related work main focus cryptographic technique proposed work secure and lightweight cipher for iot healthcare using snake key generation snake key generator and bee swarm key generator ogundokun et al. [11] crypto-stegno framework for securing healthcare data in iot crypto-stegno abdellatif et al. [12] bc-based healthcare solution for emergency response and remote monitoring bc pandey et al. [13] healthcare cybersecurity architecture using bc, dbn and resnet bc, dbn and resnet veeramakali et al. [14] cryptographic iot security authentication scheme using ohe and dnn ohe and dnn abd el-latif et al. [15] secure bc-based e-healthcare architecture using opso and odnn opso and odnn cao et al. [16] authentication and encryption system using quantuminspired quantum walks quantum-inspired quantum walks shankar et al. [17] bc-focused ico specialised in cybersecurity using a random neural network model bc and random neural network model mathews et al. [18] improved two arch2 solution for scalability and faster bc time two arch2 8. conclusion a detailed examination of iot healthcare security, bc application and cryptographic robustness in multiple stages illustrates the improved data security achieved using novel optimisation methods. specifically, the so method surpasses the bee swarm technique in several critical aspects, making it a beneficial selection for bcbased healthcare applications focused on data privacy issues. the snake key generator demonstrated improved performance in important nist randomness tests, notably the cumulative sums tests (forward and reverse), which measure the sum of sequential random variables. these results showed how snake maintains high randomness and unpredictability, effectively securing sensitive patient data against various cryptographic attacks. furthermore, the so strategy’s resiliency has shown growing robustness against possible cryptographic attacks. the keys generated using this method were virtually impossible to break within a short period (even for those that are longer function only because, even with the efficiency of current algorithms, the quantity of operations required to break the key is out of reach, making them resistant to common attack methodologies, including brute force and attacks against current cryptographic hash functions). in healthcare, ensuring the confidentiality of highly sensitive data is paramount. furthermore, the snake key generator is computationally efficient, providing for leaner and meaner key creation whilst maintaining security. this factor is important in the iot landscape, where computational resources are often limited. the key generator implemented in the snake can work in constrained environments, making it a valuable tool for iot security. although the snake key generator efficiently outperformed other routines in various tests, the runs test showed that its randomness is imperfect. this finding implies that even sophisticated iterations of the so process may encounter problems. addressing vulnerabilities is essential, as any security solution must be continuously tested against emerging threats and unforeseen scenarios. references [1] s. a. butt, j. l. diaz-martinez, t. jamal, a. ali, e. de-la-hoz-franco, and m. shoaib, “iot smart health security threats,” in 2019 19th international conference on computational science and its applications (iccsa) (ieee, saint petersburg, russia, 2019) pp. 26–31, doi: 10.1109/iccsa.2019.000-8 . 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(2021). speck-r: an ultra-light-weight cryptographic scheme for internet of things. multimedia tools and applications, 80(11), 17067-17102 doi: https://doi.org/10.1007/s11042-020-09625-8 (2025) 35-48، صفحة 1العدد، 21مجلة الخوارزمي الهندسية المجلد سجى كريم اسماعيل 48 تطبيق شيفرة آمنة وخفيفة الوزن للتطبيقات الصحية في إنترنت األشياء المقيدة بالموارد باستخدام توليد مفاتيح األفعى 3ألوهاب عبد، أحمد بهاء الدين 2محمد إبراهيم شجاع ،*1سجى كريم إسماعيل كلية الهندسة الكهربائية التقنية، الجامعة التقنية الوسطى، بغداد، العراق 1،2 الكلية التقنية لإلدارة، الجامعة التقنية الوسطى، بغداد، العراق 3 bbc0071@mtu.edu.iqالبريد االلكتروني: * المستخلص قييي يل الطبي إن دمج إنترنت األشيييياي اي الرةاية الةييي ية د طير الطريقة التي يتم بها مرا بة ال عايير الجيييييولويية، م ا يعبي بقيييك كبير درا الت تقنية البلوك تقين. ورةاية ال رضى. ييتكقف هذا الب ث تطبيق تقنيا التقجير ال تقدمة لتأمين أنظ ة الرةاية الة ية إلنترنت األشياي، وخاصة من خالل اي تعبيب أمان البيانا داخ إطار ة ائم ةلى -مولد مجتاح سيييييرح الن ومولد مجتاح األاعى -يركب الب ث ةلى تقييم اعالية مولدي ال جاتيح التقيييييجيرية داي هذه ال ولدا من حيث العقوائية، وال قاومة ل قارنة أ nistالبلوك تقين ل را بة ال رضى ةن بعد. يجري دراستنا سليلة من اختبارا العقوائية لـييييييي اي توليد ال جاتيح وتغطية للهج ا التقييجيرية، والكجاية ال يييابية. تظهر النتائج أن مولد مجتاح األاعى بقييك ةا يقد أداي أاايي اي ا يتعلق ببيادة العقييوائية يانا الرةاية الةي ية ال ه ة، وهو ياند رئيييي نظرا لتعقيد أيهبة إنترنت األشيياي، التي أمان أااي لل يياحة التوييهية. يتبين أن هذا مناسيد يدا لتأمين ب ركة بين النقطة التي د تنق بيانا صيي ة ال رضييى ال ه ة. يغطي الب ث أياييا بنية التقييجير قا الطبقتين ال يييت دمة لتأمين البيانا أنناي اليييكون وأنناي ال إلى الت بين طوي األمد. هذا النهج ضروري لل جاظ ةلى خةوصية وسالمة بيانا ال رضى، وهو أمر بالغ األه ية لا ان يتم ي عها بواسطة ال يتقعر قجير اآلمنة والجعالة الثقة اي أنظ ة الرةاية الة ية إلنترنت األشياي. يهدف هذا الع إلى أن يكون دراسة شاملة ومقارنة لتيهي التطور ال يت ر ل لول الت منية الجريدة لهذا ال جال قابلة للتوسع اي مجال الرةاية الة ية إلنترنت األشياي، م ا يبري أه ية اختيار تقنية توليد ال جتاح األ وى للتعام مع الت ديا األوال الجديد. file:///c:/users/21623/appdata/local/microsoft/windows/inetcache/ie/ed1xr2lv/bbc0071@mtu.edu.iq abstract 1. introduction 2. related work 3. iot ecosystem 4. block chain 5. iot security 5.1. speck cryptography 5.2. bee swarm optimiser 5.3. snake optimisation 6. proposed methodology 7. experimental results 8. conclusion references al-khwarizmiii eeengineering journal al-khwarizmi engineering journal, vol.3, no.1, pp 40-47, (2007) ٤٠ an experimental comparative study between polypropylene and laminated lower limb prosthetic socket dr. muhsin j. jweeg dr. samira k. radhi haider f. neama, m.sc. mechanical eng.department mechanical eng.department mechanical eng.department nahrain university al-mustansiriya university baghdad university (received 21 august 2006; accepted 19 december 2006) abstract: most researchers concentrate their studies on the design, stress and pressure distributions of the prosthetic socket. a little attention is considered for the stiffness of the various materials of the prosthetic sockets. prosthetic laminated sockets in iraq are costly to be manufactured while polypropylene socket is relatively cheap in comparing with the laminates. experimental study is conducted to compare the stiffness of five prosthetic sockets made of different materials. compression, three point flexural and tensile tests are implemented by the testometric machine. the laminate sockets give better results in compression than polypropylene. polypropylene gives good results in bending compared with the laminate sockets. when the socket loads are mainly in compression i.e. the low activity level patients, it seems that any of the tested sockets could be used, however, when the load will be not only in compression but in flexion as well i.e. high activity patients, socket no.1 and 5 could be used. keywords::: prosthetic, socket, laminate, polypropylene and stiffness. 1-introduction the studies concerning the prosthetic socket are always about the pressure distribution of the socket, ignoring the materials of it. appoldt and bennett[1], found the loading on an above-knee fiberglass socket by building the socket with the pressure transducers incorporated. unfortunately their results are only accurate for the single socket used in the experiment. this is due to all modern sockets having different geometries and external loads due to differences in the amputees. bielefeldt and schreck[2], investigated the difference in loading of four different material sockets, during stance phase, for the same patient. their sockets were built with transducers incorporated. joshua et. al.[3], developed a new rapid prototyping method for fabrication of prosthetic socket. the system, referred to as squirt shape, fabricates sockets by extruding a continuous bead of molten plastic and laying it down in the desired socket form. this technique eliminates intermediary steps (e.g., fabrication of plaster blanks and carving of socket positives) used in contemporary cad/cam of prosthetics, and enables the socket to be fabricated in a single operation. ross stewart[4], devised an experiment to quantify the effectiveness of various suspension system. a transtibial limb was constructed to have similar anatomical feature and skin interface characteristics as an anatomical residual... to do this, vacuum, strap and anatomical suspension transtibial prosthetic socket could be done. this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr.muhsin j. jweeg\al-khwarizmi engineering journal ,vol.3, no. 1 pp 40-46(2007) ٤١ by using a tensile tester, a graph of the tensile force versus displacement was obtained. this work can be achieved to test the strength and stiffness of the material of the prosthetic socket. matt fleming[5], conducted a similar experiment to stewart’s experiment, but in this case a real transtibial prosthetic patient is tested. the subject was cast and fitted with four different suspension systems. in the experiment each socket was donned by the subject and the displacement of the socket/liner was measured with various weights added to the set-up. arthur f.t. et. al.[6], reviewed the recent research literature on socket biomechanics, including socket pressure measurement, friction, computation modeling, and limb tissue responses to external loads and other physical conditions. it was noted that an understanding of comfort and optimal load transfer as patterns of socket interface stress could culminate in socket design. winson c.c. et. al.[7], perform a finite element analysis to determine the effect of monolimb flexibility on structural strength and interaction between residual limb and prosthetic socket. 2experimental programme 1 prosthetic socket manufacturing -2 the polypropylene and laminations are manufactured on plaster mold of cylindrical shape (100mm in diameter and 500mm in length). the mold is fastened to a vaccum device and covered with a nylon stockinette (woman socks). a heated sheet of polypropylene is fitted over the mold, while for laminations a pva is pulled on the mold. the layup materials are then pulled onto the mold and placed under tension. once all layup materials has been pulled onto the pipe, another pva is pulled over the layup and tightened below the vaccum. at this point the layup is ready to laminate. the resin is added, then the vaccum is turned on. once polypropylene and laminations are completed, they are cut to test size, as shown in fig.1. for the compression test a 50mm length of polypropylene and lamination is used whilst a 140mm length is used for the flexural test. the compression test gives an indication of comparative socket stiffness whilst the flexural test provides us the results which can be related to the clinical situation of socket loading. for tensile test, polypropylene material with 12 layers of laminate are chosen to compare between thermoplastic and composite material. table 1 shows the sockets for the testing purposes. 3experimental procedure testing of polypropylene and lamination pieces are completed with the use of a testometric testing machine. the compression and flexural test pieces are positioned in the testometric on the crosshead by suitable grips. 25000 n full scale load and 10mm/min crosshead speed are set. fig.2 and fig.3 shows the tested specimens used for compression and bending tests, while fig.4 shows the position of the sample for the flexural test. calculations of the flexural strengths of the tested sockets are shown in the appendix. d638(astm standard) is used for sizing the polypropylene and laminated samples for tensile test. fig.5 shows the sizes for polypropylene and no.5 socket (12-layers of laminate). for polypropylene material, the necking of the test piece should be occurred during 100 seconds. therefore, trial pieces were tested at different cross head speeds to get the correct results. for the laminate piece, the cross head speed is 5mm/min.the tensile tested pieces for no.1 and no.5 sockets are positioned on the testometric machine by a suitable grips. 4-results from table 2 and fig.6, it can be noticed that socket no.5 has the largest compressive stiffness, followed by sockets no.4, no.3, no.1 and no.2 respectively. the difference in compressive stiffness between the laminated sockets is not significant, while there is relatively apparent difference between sockets no.5 and no.1. this is due to the fibers strength in the direction of the load. for the fracture compression stresses , there are differences in this aspect. sockets no.1, no.4 and no.5 do not fracture, and they tolerate larger than 25000 n as compression this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr.muhsin j. jweeg\al-khwarizmi engineering journal ,vol.3, no. 1 pp 40-46(2007) ٤٢ loads. while no.2 and no.3 sockets tolerate 21000 n and 23000 n respectively. there is a difference in the nature of the fracture of polypropylene and laminated socket. for polypropylene, failure starts with stress whitening phenomenon in the socket with final fracture in the bonding region, while for laminated socket, fracture starts with resin failure. for flexural bending test, polypropylene sample deflects to more than 4mm and after unloading the bending load, the sample seems to return to its original shape with small plastic deformation. for laminates samples, failure is apparent by fracturing the resin. from table 2 and fig.7, sockets no.5 and no.1 have the largest flexion stiffness, followed by no.4, no.3 and no.2 sockets. fig.8 shows the experimental results of the tensile test for socket no.1 and no.2. for polypropylene material (socket no.1), the material properties are,e=1.235 gpa, σult. =33.5 mpa, σy = 25 mpa. the polypropylene does not have a well-defined yield point, and consequently the graphical method of offset method is used to define the yield point. normally, a 0.2 % strain is chosen, and from this point on the strain axis, a line parallel to the initial straight line portion of the stressstrain diagram is drawn. the point where this line intersects the curve defines the yield strength. it is found that polypropylene is an extended material under tensile load or no.5 socket, the material properties are, e= 2.092 gpa, σult. =48.97 mpa. the socket no.5 (laminated socket) undergoes a little deformation before its final fracture because of its brittleness. 5-discussion the prosthetists consider laminated sockets stronger than polypropylene in all mechanical properties. through the tests, it is found that compressive stiffness of lamination is larger than polypropylene with not very high difference. from fig.5 it should be noted that the socket no.1&2 (polypropylene) have more deflection than the rest sockets(laminations), and this means that the ductility of polypropylene is greater than laminations. this is a useful factor if we take into considerations the pressure relief regions of patient's stump(truncated part of his leg). for the bending test, it should be noted from fig.6 that all the sockets in the bending test pass through three stages: 1. linear behavior at the first stage. 2. appearance of the effect of the sample slipping over the supports as the deflection increases at the second stage. it should be noted that the sample slipping does not affect the stiffness which is evaluated at the first stage. 3. then, failure of the sample by the effect of the maximum load. socket no.1(polypropylene,5mm) has better flexural stiffness than the tested laminated sockets except socket no.5 which has a very little higher stiffness than socket no.1 socket. in the bending test, the stiffness of laminated sockets depends upon the types and the amount of the resin in addition to the fibers. the problem is that the manufacturers in the medical rehabilitation centers do not use the sufficient amount of resin because of its high cost. while the modulus(stiffness) of a laminate depends upon fiber and resin volume fractions. it should be noted that stiffness of sockets no.5 and no.1 are approximate. 6-conclusions 1. when the socket loads are mainly in compression i.e. the low activity level patients, it seems that any of the tested sockets could be used, however, when the load will be not only in compression but in flexion as well i.e. high activity patients, socket no.1 could be used. 2. in iraq, polypropylene is good selected material compared with laminates, because of its good mechanical properties and cost. references [1] appoldt and bennet;" a preliminary report on dynamic socket pressures"; bull prosthetic res.; 1967. [2] bielefeldt and schreck; "the altered alignment influence on above knee prosthesis socket pressure distribution"; this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr.muhsin j. jweeg\al-khwarizmi engineering journal ,vol.3, no. 1 pp 40-46(2007) 3 international series on biomechanics viia; 1981: 387-393. [3] joshua s. rovick & dudley s. childress;" an additive fabrication technique for the cam of prosthetic sockets"; (va project number: a711-da); 1995. [4] matt flamming;" clinical evaluation of trans-tibial suspension system"; monash rehabilitation technology research unit; 1998. [5] ross stewart;" tran-tibial syspension system", monash rehabilitation technology research unit; 1998. [6] arthur f.t. mak,phd,ming zhang,phd & david a.boon,"state-of-the-are research in lower limb prosthetic biomechanics socket interface",jrrd,vol.38 no.2 march/april 2003. [7] winson c.c.lee,bsc,ming zhang,phd,"finite element analysis to determine effect of monolimb flexibility on structural strength and interaction between residual limb and prosthetic socket", jrrd,vol.41,no.6a,nov.2004. [8] r.c. hibbler;" mechanics of materials"; prentice hall international, inc. appendix calculations concerning flexural tests fig.9 shows the cross-sectional of the bending sample. the equations used in calculation of the bending strenfths are as follows: xc= (2/3)(r)(sinα/α) (1-t/r+(1/(2-t/r))) x1= r-xc x2= xc-(r)(cosα) iy=(r4-r4)/8(2α+sin2α) ic=iy-(r2-r2)(α)(xc2) σt= (m)(x1/ic) σc= (m)(x2/ic) table 1 the test sockets socket no. material 1 5mm polypropylene 2 2mm polypropylene 3 perlon (10-layers)with orthocryl resin. 4 nyglass(8-layers)with orthocryl resin. 5 perlon(2-layers),nyglass(2-layers),fiberglass(2-layers), nyglass(2-layers),fiberglass(2-layers) and perlon(2-layers)with polyster resin. table 2 summary of results for experimental tests socket no. thickness mm compression test flexural bending test cross sectional area mm2 compressive stiffness(kc)n/mm flexural stiffness(kb)n/mm σt mpa σc mpa 1 5 1884.956 8333 32.4 30.17 39.429 2 2 779.114 7222 16.67 27.11 41.73 3 2 779.114 9000 18.5 24 36.96 4 3 1178.097 9524 20 32.58 46.63 5 3.5 1280.98 10364 33.33 44.43 62.38 this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr.muhsin j. jweeg\al-khwarizmi engineering journal ,vol.3, no. 1 pp 40-46(2007) 4 table 3 the parameters used in finding tensile & compression bending stresses for bending test parameter socket no.1 socket no.2 socket no.3 socket no.4 socket no.5 r mm 62.5 63 63 64 60 r mm 57.5 61 61 61 56.5 α degree 20.609º 20.438º 20.438º 20.105º 21.51º xc 58.748 60.698 60.698 61.237 56.908 x1 3.75 2.3 2.3 2.763 3.091 x2 4.9 3.54 3.54 3.954 4.34 ic 714.576 148.45 148.45 264.961 373.935 fmax n 230 70 62 125 215 m n.m 5750 1750 1550 3125 5375 fig.1 the socket and the test pieces fig.3 bending test specimen fig.2 compression test specimen fig.4 bending test of socket this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr.muhsin j. jweeg\al-khwarizmi engineering journal ,vol.3, no. 1 pp 40-46(2007) 5 fig.5 dimension of tensile specimen(d638) 0.00 2.00 4.00 6.00 8.00 deflection(mm) 0.00 40.00 80.00 120.00 160.00 lo ad (n ) socket no.1 socket no.2 socket no.3 socket no.4 socket no.5 fig.6 compression graphs for all sockets 0.00 5.00 10.00 15.00 20.00 25.00 strain(%) 0.00 10.00 20.00 30.00 40.00 50.00 s tr e s s (m p a) socket no.1 socket no.5 fig.8 tensile test for socket no.1&5 0.00 2.00 4.00 6.00 deflection(mm) 0.00 5000.00 10000.00 15000.00 20000.00 25000.00 lo a d( n ) socket no.1 socket no.2 socket no.3 socket no.4 socket no.5 fig.7 flexural bending graphs for all sockets fig.9 cross section of the bending sample this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ dr.muhsin j. jweeg\al-khwarizmi engineering journal ,vol.3, no. 1 pp 40-46(2007) 6 دراسة تجریبیة لمقارنة بین وقب البولي بروبلین والمواد المركبة للطرف ).الصناعي( السفلي البدیل حیدر فانوس نعمة. سمیرة كریم راضي أ. محسن جبر جویج د. د كلیة الھندسة قسم المیكانیك كلیة الھندسة قسم المیكانیك كلیة الھندسة قسم المیكانیك جامعة النھرین الجامعة المستنصریة جامعة بغداد :الخالصة م الب ز معظ دیل یرك ناعي الب ب الص غوط للوق ادات و الض ع االجھ میم و توزی ى تص اتھم عل ان (احثین دراس رف االنس ن ط ع ن (ان سعر االوقاب الطبقیة. المواد المصنوع منھا الوقب البدیل (stiffness)،و یكون االھتمام قلیًال بجساءة) المبتور المصنوعة م .قارنة بالوقب المصنوع من مادة البولي بروبلین الذي یكون سعره زھیدًاالبدیلة یكون غالیًا جداًً م)عدة طبقات من االلیاف ة أ واد مختلف ن م غط، . جریت دراسة عملیة لغرض مقارنة جساءة خمسة أنواع من االوقاب البدیلة مصنوعة م ار الض ري اختب أج ب الطبق ئمن خالل النتا. testometricواختبار االنحناء و الشّد بماكنة ل يج وجد أنھ الوق ن الحم اتج م وه الن ة للتش ك مقاوم یمتل روبلین (االنضغاطي اكبر من تلك للبولي بروبلین ولي ب ك للب ن تل ى م غاط اعل ر ) جساءة الوقب الطبقي في حالة االنض و أن األخی م ب رق دا الوق ي ع ب الطبق واع الوق ل ان ن ك ر م خاص . ٥یمتلك مقاومة للتشوه الناتج من الحمل أالنثنائي اكب ة ان االش ذوي فعالی غاطیة اءة االنض یم الجس ھ ق اب الن ن االوق تخدام اي م ن اس ذا یمك غاطي وبھ ب انض ى الوق المشي الواطئة یكون اغلب التحمیل عل ب ى الوق ل عل ب التحمی ون اغل ذي یك ة ال ة العالی خاص ذوي الفعالی ا االش ي، بینم ب الطبق لیة للوق ع افض ة م ا متقارب ًا م نوع .ملم٥ووقب البولي بروبیلین ذو سمك ) الذي یمتلك اعلى الطبقات( ٥دام الوقب الطبقي رقم یتم استخ(flexural)انثنائي this page was created using nitro pdf trial software. to purchase, go to http://www.nitropdf.com/ http://www.nitropdf.com/ <4d6963726f736f667420576f7264202d20c8d4d1ec20e6e3c7e5d120e6c7cde3cf20e3cdd1e6d332392d3434> this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 17, no. 3, sptember, (2021) p. p. 29-44 simulation of a self-balancing platform on the mobile car bushra amer tawfeeq* maher yahya salloom** ahmed alkamachi*** *,**,*** department of mechatronics engineering/ al-khwarizmi engineering college/ university of baghdad *email: bushra.a.tawfeeq@gmail.com **email: drmahir@kecbu.uobaghdad.edu.iq ***email: ahmed78@kecbu.uobaghdad.edu.iq (received 27 july 2021; revised 17 september 2021; accepted 29 september 2021) https://doi.org/10.22153/kej.2021.09.003 abstract in the last years, the self-balancing platform has become one of the most common candidates to use in many applications such as flight, biomedical fields, industry. this paper introduced the simulated model of a proposed selfbalancing platform that described the self–balancing attitude in (x-axis, y-axis, or both axis) under the influence of road disturbance. to simulate the self-balanced platform's performance during the tilt, an integration between solidworks, simscape, and simulink toolboxes in matlab was used. the platform's dynamic model was drawn in solidworks and exported as a step file used in the simscape multibody environment. the system is controlled using the proportional-integral-derivative (pid) controller to maintain the platform leveled and compensate for any road disturbances. several road disturbances scenarios were designed in the x-axis, y-axis, or both axis (the pitch and roll angles) to examine the controller effectiveness. the simulation results indicate that that the platform completed selfbalancing under the effect of disturbance (10° and -10°) on the x-axis, y-axis, and both axes in less than two milliseconds. therefore, a proposed self-balancing platform's simulated model has a high self-balancing accuracy and meets operational requirements despite its simple design. keywords: self-balancing platform, (pid) controller, solid work, software, matlab, simscape multibody, package. 1. introduction the self-balancing platform has always been a very challenging area to work on. it was elevated to a new level by introducing modern technologies, such as a pid controller, an imu sensor (gyroscope and accelerometer), model simulation [1]. self–balancing platform has witnessed a change in the shape and size depending on: the degree of freedom (tilt direction), driving mechanism, control system, the type of internal measurement unit(imu), supplement machinery size (whether it is a cart, or agricultural machinery, or a simple robot smart car.), and weight of the load [2]. the compensation for the platform's angular fluctuation during its movement in the uneven ground makes measuring the platform's tilt angle by a potentiometer or more advanced sensors more necessary. the obvious choice for compensating the platform's tilt is motor, such as servo motors, stepper motors, and dc motors [3]. mathworks's mechanism to design, model, simulate, and result-validate any physical or mechanical system is the simscape multibody library [4][5]. simscape multibody software is developed so that its block libraries are used to simulate the mechanical system according to basic physical principles (newtonian dynamic of forces and torque). in contrast, simulink blocks symbolize the system's mathematical operations or the processes on the signals. still, simscape multibody software works in the simulink environment and interface with simulink and bushra amer tawfeeq al-khwarizmi engineering journal, vol. 17, no. 3, p.p. 2944(2021) 30 matlab flawlessly [6][7]. the simulink and simscape software has been used to build and control the inverted pendulum system without the need to derive a complicated system of mathematical differential equations [8]. the experimental results of the 2dof selfbalancing platform are shown the presence of the pid controller's fine-tuned coefficients limiting the overshoot and settling time and no steady-state error. the coefficient is analyzed by the simulation aspects (matlab) and used to maintain the platform at an initially nominated angle when the structure's tilt is in the x-axis or y-axis (the pitch and roll angles). the two servo motors depend on the pid controller's feedback to support and balance the top wood platform through tilt [9]. self-balancing platform with 2dof on a cart simulated model relies upon matlabsimmechanics and simulink of dc motor. the model was configured as an inverted pendulum conception in a square-shaped with each side measuring 30 cm attached with the three links that covered all required support of the platform. satisfactory performance of the existing platform, stability, re-correct timeless than 1second, and the highest level of precision in determining the servomotor's next position is among the ones that have been attributed to using the matlabsimmechanics simulation and simulink of dc motor [10]. platform's simmechanics simulation has been a fundamental parameter indicating the relationship between the platform's navigation parameters (roll, yaw, and pitch angles) and selecting the pid coefficient regarding the servomotor's rotation angle. also, the simulation named the most critical limits that should exceed in the design as the platform contained the arduino uno control the servomotors through three links to regulate the platform's tilt [11]. in terms of meeting the top plate in the 6 dof platform, namely, vehicle stabilizer, balance requirements when there is an alter of the base plate's position. the simscape simulation has been added. the vehicle stabilizer's simulated model had involved six linear actuators connected to the base plate and top plate with universal joints. the simscape simulation's result of vehicle stabilizer has been assessed; this leads to the conclusion that the pd controller's availability to select linear actuators' desired position is adequate to stabilize the upper platform's position, especially at large angles (more than 45° on all axis) [12]. the displacement curve and the force curves of six hydraulic cylinders of the 6dof hydraulic platform are extracted from kinematic simulation (matlab) and dynamic modelling (solidworks/ adams software). the displacement curve application gave good results that helped the platform's hydraulic cylinders run smoothly and continuously during the self-levelling. the dynamic modelling is used to select suitable materials for (upper and lower planes, hydraulic cylinders, hinge circuits) to hold out the cylinder's maximum extension force and the maximum binding force of the ball hinge [13]. a genetic algorithm(ga)is a global algorithm base on darwin's theory of evolution. genetic algorithm is one of the pid controller optimization methods, especially if the pid controller interconnected system is a dc motor [14]. accordingly, the genetic algorithm often provides a reasonable balance between the pid controller coefficient's accurate values and better pid response regarding the rise time and the settling time. ga consists of four main stages (initial generation, cost function, selection techniques, crossover, and mutation [15] [16] [17]. this study’s main contribution is use of the solidworks and simscape environments to build, model, and control the proposed self-balancing platform’s simulated model without the need to derive a complex system of mathematical differential equations. 2. methodology the simulated model of the proposed selfbalancing platform on the mobile car has been built based on the working principle of the block diagram shown in figure.1. bushra amer tawfeeq al-khwarizmi engineering journal, vol. 17, no. 3, p.p. 2944(2021) 31 fig. 1. the block diagram of simscape / simulink model of self-balancing platform on the mobile car. 3. simscape / simulink model of the proposed self-balancing platform on the mobile car the simscape / simulink model of the proposed self-balancing platform on the mobile car, consisting of five main simulink subsystems. the subsystems in the simulated model of the self-balancing platform on the mobile car, except platform subsystem, have been designed by (matlab r2020a) / simulink. the platform subsystem was designed by solidworks(sw2020), then imported to matlab/ simulink through the matlabsimscape multibody package / (matlab r2020a). 3. 1. input parameters subsystem the input parameters participants in the simulated model of the self-balancing platform on the mobile car (for x-axis /middle plate or y-axis / top plate) were divided into two different inputs; one of the inputs defined as the set point of roll or pitch angles (0° = 0 radians) and entered by a (matlab r2020a)/ simulink library browser / constant value block to pid controller of the respective plate. the second input mimics a road disturbances signal (tilt angles (in degree) in the x-axis or y-axis, or both axes), designed by a (matlab r2020a) / simulink library browser/ signal builder block. the degrees to radian block converted the tilt angles of disturbances signal to radian before entering the plate's pid controller. the input parameters subsystem is shown in figure.2. fig. 2. input parameters subsystem. 3.2. pid controller subsystem according to the mathematical modeling of eq. (1) [18] [19], the two pid controllers of the simulated model for the self-balancing platform on the mobile car have been established by matlab (r2020a) / simulink. pid controller subsystem contained two controllers; one pid controller is for the pitch angle y-axis (top late), the other pid controller for the roll angle x-axis (middle plate) as shown in figure.3. bushra amer tawfeeq al-khwarizmi engineering journal, vol. 17, no. 3, p.p. 2944(2021) 32 u �t� � kp e �t� � ki � ����� � � � kd de/ dt … (1) where: kp: the proportional value. ki: the integral value. kd: the derivative value; et is the error function; t is the time. a. pid controller for roll angle x-axis. b. pid controller pitch angle y-axis. fig. 3. pid controller subsystem. 3.3 dc servo motor subsystem the motor's mathematical model describes the motor's performance using mathematical equations [20] [21]. the following mathematical modelling and kinematics modelling formulas have been used with matlab r2020a /simulink's functionality to dispensing the dc servo motor's intricate design by solidworks and replace it with a simple simulated model. this method has been used for both dc servo motors of the simulated model for the self-balancing platform on the mobile car. dc servo motor subsystem contained two dc servo motors, one of the motors is for the pitch angle y-axis (top plate), the other motor is for the roll angle xaxis (middle plate), as shown in the figure. 4. the kinematics modelling of dc servo motor for both pitch angle y-axis servo motor and the roll angle x-axis servo motor (shown in figure.4) were simulated in simulink as shown in fig. figure.6. according to the equations (2) and (3) [22], the below block diagram of the dc servo motor is shown in figure.5 [23] and the motor parameters in the table1. for this simulation, the parameters of an actual dc servo motor were chosen from [19] and shown in table1. bushra amer tawfeeq al-khwarizmi engineering journal, vol. 17, no. 3, p.p. 2944(2021) 33 fig. 4. dc servo motor subsystem. �position(�)= ���� � ��� � �� ���� !���"� #� �$�� % &� … (2) �speed(�)= � ( ��� ���� = �� ���� !���"� #� �$�� … (3) where∶ *+ : armature resistance, ohm. ,+ : armature inductance, henry. i: armature current, ampere. .+ : armature voltage, volts. ./ : back emf, volts. 0/ : back emf constant, volt/(rad/sec). 01 : torque constant, n-m/ampere. 21 : torque developed by the motor, n-m. 2& : torque developed by the load, n-m. 23 : disturbance torque, n-m. θ(t): angular displacement of shaft, radians. j : moment of inertia of the motor and load, kg m5 /rad. b: frictional constant of motor and load, nm/(rad/sec). fig. 5. block diagram of dc servo motor [23]. table 1, actual dc servo motor parameters [23]. s.no. parameters values 1 armature resistance (r-) 1.17 ohm 2 armature inductance (l-) 0.5h 3 coulomb friction torque (b) 0.01 n-m/(rad/sec) 4 rotor inertia (j) 0.01 kgm5 /rad 5 motor torque constant (k8) 0.1 v/rad/sec 6 back emf constant (k9) 0.٦1 n.m/ ampere 7 operating voltage (v) 12v 8 operating current (i) 2.28a 9 maximum torque 8kg-cm bushra amer tawfeeq al-khwarizmi engineering journal, vol. 17, no. 3, p.p. 2944(2021) 34 fig. 6. kinematics modelling of dc servo motor using simulink. 3. 4. platform subsystem in terms of dynamic modelling, a 3d model of the self-balanced platform on the mobile car was constructed and optimized by solidworks(sw2020) based on the design parameters and related limitations. the platform's complete system (three plates and two holders) consisted of lightweight material (perspex gs cast acrylic glass 6mm thickness) with a dimension of (45 cm length × 30 cm width) at the rectangle base plate (40cm length× 40 cm width× 3cm inside) at the square middle plate, (20cm length× 20 cm width) the square top plate and each holder with (15cm width× 25cm height). besides, the platform attached to a reliable iron rectangle that had the advantage of having a well-balanced structure (45cm length × 60 cm width) stands on four tires, as shown in figure.7. matlabsimscape multibody package (matlab r2020a) was used to personify the 3d solidworks design of the selfbalancing platform on the mobile car as matlab simscape model. figure.8 illustrates the simscape model of the self-balancing platform on the mobile car. fig. 7. the cad drawing for the proposed prototype of the 3d self-balancing platform on mobile car. bushra amer tawfeeq al-khwarizmi engineering journal, vol. 17, no. 3, p.p. 2944(2021) 35 fig. 8. the simscape model of the self-balancing platform on the mobile car. 3.5. sensor subsystem six revolute joints were used to connect eight rigid frames to each other due to conversion from the cad design of the self-balancing platform on the mobile car to the simscape model. each revolute joint represents position relation type between platform cad's sub-assemblies. the used technique for applying torque (n-m) to rotate the plate's (either middle or top) for self-balancing the plate's inclination is a revolute joint primitive/ actuation properties / actuation torque setting (t) [24] [25] as shown in figure.9. the dc servo motor was simulated by matlab / simulink, and the joint connection between the plate (either middle or top) and the dc servo motor is a simscape block. therefore, the s-ps (simulink physical system) converter block is used to interface the two toolboxes with each other. the used sensing technique for registering the plate's (middle and top) actual current angle value (roll and pitch angles) after self-balancing is firstly plate's actual velocity is measured (rad/sec) by a revolute joint primitive/ sensing properties / relative angular velocity option(w) [24] [25]. then, the plate's actual velocity converts to the plate's actual angle(rad) by simulink/ integrator block. the joint connection between the plate (either middle or top) and dc servo motor is a simscape block, and the integrator block is a simulink block. therefore, the ps-s (physical system simulink) converter block is used to interface the two toolboxes with each other. the pid controller output depends on revolute joint sensing's feedback to re-correct the tilt of the platform. the sensing technique in the sensor subsystem is shown in figure.9. bushra amer tawfeeq al-khwarizmi engineering journal, vol. 17, no. 3, p.p. 2944(2021) 36 fig. 9. torque applying technique and angles sensing technique. 4. results and discussion the simulated model of the self-balancing platform on the mobile car was tested in a simulink environment included in (matlab r2020a) to validate simulated model capabilities to self-balancing under disturbance scenarios. the simulation results were attained by self-balancing verification of the simulated model of the selfbalancing platform on the mobile car in matlab r2020a /simulink. this verification was repeated four times, one for each disturbance scenario shown below in the four cases. case one: self-balancing attitude in the simulated model under the influence of road disturbance scenario in the x-axis. the self-balancing behavior of the simulated model for the self-balancing platform on the mobile car resulted from the platform's simulated model subjected to disturbance (tilt angle 10° on positive x-axis and -10° on negative x-axis) is shown in figure 10. the self-balancing of the (platform on the mobile car) structure in the virtual simulation environment under tilt angle 10° on positive x-axis and -10° on negative xaxis is shown in figure 11: (a, b). a. under tilt angle 10° on positive x-axis. bushra amer tawfeeq al-khwarizmi engineering journal, vol. 17, no. 3, p.p. 2944(2021) 37 b. under tilt angle -10° on negative x-axis. fig. 10. self-balancing behavior of simulated model on x-axis. a b fig. 11. self-balancing of the (platform on the mobile car a) structure in the virtual simulation a) under tilt angle 10° on positive x-axis b) under tilt angle -10° on negative x-axis. case two: self-balancing attitude in the simulated model under the influence of road disturbances scenario in the y-axis. the self-balancing behavior of the simulated model for the self-balancing platform on the mobile car resulted from the platform's simulated model subjected to disturbance (tilt angle 10° on positive y-axis and -10° on negative y-axis) is shown in figure 12. the self-balancing of the (platform on the mobile car) structure in the virtual simulation environment under tilt angle 10° on positive y-axis and -10° on negative yaxis is shown in figure 13: (a, b). a. under tilt angle 10° on positive y-axis. bushra amer tawfeeq al-khwarizmi engineering journal, vol. 17, no. 3, p.p. 2944(2021) 38 b. under tilt angle -10° on negative y-axis. fig. 12. self-balancing behavior of simulated model on y-axis. a b fig. 13. self-balancing of the (platform on the mobile car) structure in the virtual simulation a) under tilt angle 10° on positive y-axis b) under tilt angle -10° on negative y-axis. case three: self-balancing attitude of the simulated model under the influence of road disturbances scenario in the biaxial (contradictory tilt angles in x-axis and y-axis) the self-balancing behavior of the simulated model for the self-balancing platform on the mobile car as a result of the platform's simulated model subjected to disturbances (tilt angle 10° on positive x-axis and -10° on negative y-axis) and (tilt angle -10° on negative x-axis and 10° on positive y-axis) shown in figure 14. the selfbalancing of the (platform on the mobile car) structure in the virtual simulation environment under tilt angle (10° on positive x-axis and -10° on negative y-axis) and tilt angle (-10° on negative x-axis and 10° on positive y-axis) is shown in figure 15: (a, b). a. under tilt angle (10° on positive x-axis and -10° on negative y-axis. bushra amer tawfeeq al-khwarizmi engineering journal, vol. 17, no. 3, p.p. 2944(2021) 39 b. under tilt angle (-10° on negative x-axis and 10° on positive y-axis). fig. 14. self-balancing behavior of simulated model on (contradictory tilt angles in x-axis and y-axis). a b fig. 15. self-balancing of the (platform on the mobile car) structure in the virtual simulation a) under tilt angle (10° on positive x-axis and -10° on negative y-axis) b) under tilt angle (-10° on negative x-axis and 10° on positive y-axis). case four: self-balancing attitude of the simulated model under the influence of road disturbances scenario in the biaxial (similar tilt angles in x-axis and y-axis). the self-balancing behavior of the simulated model for the self-balancing platform on the mobile car as a result of the platform's simulated model subjected to disturbances (tilt angle 10° on positive x-axis and 10° on positive y-axis) and (tilt angle -10° on negative x-axis and -10° on negative y-axis) shown in figure 16. the selfbalancing of the (platform on the mobile car) structure in the virtual simulation environment under tilt angle (10° on positive x-axis and 10° on positive y-axis) and tilt angle (-10° on negative x-axis and -10° on negative y-axis) is shown in figure 17: (a, b). bushra amer tawfeeq al-khwarizmi engineering journal, vol. 17, no. 3, p.p. 2944(2021) 40 a. under tilt angle (10° on positive x-axis and 10° on positive y-axis). b. under tilt angle (-10° on negative x-axis and -10° on negative y-axis). fig. 16. self-balancing behavior of simulated model on (similar tilt angles in x-axis and y-axis). a b fig. 16. self-balancing of the (platform on the mobile car) structure in the virtual simulation a) under tilt angle (10° on positive x-axis and 10° on positive y-axis) b) under tilt angle (-10° on negative x-axis and -10° on negative y-axis). from the previous three cases, simulation results showed that the angle at the beginning of the error curve represents the angle value that the dc servo motor will rotate the respective plate (angle averse to the tilt angle direction from corresponding disturbances signal but in the same value) in order to overcome the tilt angle that platform exposed to. by comparing the angle in (either actual roll angle or actual pitch angle or both actual angles simultaneously) with the angle bushra amer tawfeeq al-khwarizmi engineering journal, vol. 17, no. 3, p.p. 2944(2021) 41 in the corresponding error curve, it could be observed that they are equal in value and direction. in other words, the self-balancing of the platform has been achieved. on the other hand, the recovery time (in all cases) that platform takes to set the error to zero, overcome the tilt angle and achieve self-balancing is (less than two milliseconds). low recovery time (low selfbalancing time) is attributable to the pid controllers' efficiency in handling the platform's tilt (x-axis, y-axis, and biaxial). simulation results also indicate to: firstly, the platform's simulated model overall response under the influence of disturbance scenarios in (x-axis, y-axis, or biaxial) has done smoothly and without any evident vibration. secondly, dispense the complex design of the dc servo motor by solidworks and replace it with a simulated model that did not affect the platform's performance. on the contrary, each dc servo motor proved its ability to determining torque to shift the plate's direction (counter the tilt angle direction) with proper synchronization to disturbance occurrence. thirdly, adding revolute primitive/ sensing properties makes the system more intelligent and effectively measures the platform's angle (actual roll angle or actual pitch angle or both actual angles) after self-balancing without adding a sensor. finally, the self-balancing of the (platform on the mobile car) structure in the virtual simulation represents the visualization of selfbalancing in the top plate, middle plate, and both plates, respectively. key values of simulation results were provided from matlab/scope and shown in table 2. for achieving the results above, the pid controller's parameters (for both pid controllers of the self-balancing platform simulated model) are tuned and optimized by the genetic algorithm method (ga)[26]. the following parameter values are shown in table 3 gave the best response in terms of maximum peak overshoot and response time. genetic algorithm parameters are illustrated in table 4. table 5.5shows a comparison between our self-balancing platform on the mobile car with other article references. table 2, the key values of simulation results. rise time (in all cases) 114 to 175ms overshoot (in all cases) settling time 12% when tilted in one axis, 15% when tilted in two axes. 237ms steady state error 0.09 to 0.74° table 3, optimized pid controllers’ parameters of simulated model table 4, genetic algorithm parameters. s.no. ga parameters value/ method 1. optimization tool matlab genetic algorithm toolbox 2. variable boundaries [kp ki kd] for roll angle pid controller lower [0,0,0,], upper [ 150 ,350, 1] for pitch angle pid controller lower [0,0,0,], upper [ 100 ,200, 1] � lower and upper boundaries values have been taken from primary pid parameters(for both pid controllers) tuned by trial and error. 3. maximum number of population 60 [26]. 4. size generations 100 [26]. 5. fitness value cost function/ integral of time multiplied by absolute error (itae). 6. selection method normalized geometric selection[26]. 7. crossover method arithmetic crossover [26]. 8. mutation method uniform mutation [26]. roll angle pitch angle p 45 32 i 73 59 d 0.58 0.54 bushra amer tawfeeq al-khwarizmi engineering journal, vol. 17, no. 3, p.p. 2944(2021) 42 table 5, comparison between our self-balancing platform on the mobile car with other article references. disturbance type self-balancing time our simulated model disturbances signal as tilt angle from (-10 and 10) degrees on (x-axis or y-axis or biaxial). less than 2 milliseconds [9] the disturbance that was used is the positive angle value (5 degrees) of the two axes. 0.7 seconds [10] [11] [12] pump =3 and 5 mm the platform's design is 6dof, but the platform was only tested when the base was rotated 26 degrees with the x-axis and the y-axis. tilt angle= 2-25 degrees in (x-axis & y-axis). 2.6, 1.6, 1.2 seconds in (x axis, y-axis, z-axis), respectively 50 seconds 5 seconds in both axes 5. conclusion in this paper, a simulated model of selfbalancing on the mobile car has been suggested and designed. the work results showed that when the platform is exposed to the disturbance in (xaxis, y-axis, or biaxial), the controller's decision (angle value and direction of the servo motor) depending on error measurements to overcome the platform's unbalanced situation and reduce recovery time. moreover, optimization of the pid controllers' coefficients in both (simulated model) by the genetic algorithm method effectively affected the performance of the platform, as the platform system is stable and the platform was able to compensate for the tilt angle in (x-axis, yaxis, and biaxial) and overcome the error in a time that does not exceed two milliseconds. 6. future work future work includes changing the disturbance profile of (x-axis, y-axis, or biaxial) into diverse values of tilt angles (between each angle and another a period of time) on the positive and negative side of the axis. also, add new elements to the platform's dynamic modelling design to study the self-balancing performance in six dof. 7. references [1] m. m. nadeem, s. u. khan, and d. mazhar, “dynamic self stabilizing mobile platform,” no. ieec, 2019. [2] v. popelka, “a self stabilizing platform,” proc. 2014 15th int. carpathian control conf. iccc 2014, pp. 458–462, 2014, doi: 10.1109/carpathiancc.2014.6843648. [3] y. liu, z. q. zhu, and d. howe, “instantaneous torque estimation in sensorless direct-torque-controlled brushless dc motors,” ieee trans. ind. appl., vol. 42, no. 5, pp. 1275–1283, 2006, doi: 10.1109/tia.2006.880854. [4] mohapatra, s., srivastava, r., & khera, r. (2019). “implementation of a two-wheel selfbalanced robot using matlab simscape multibody”. second international conference on advanced computational and communication paradigms (icaccp)1–3. doi:10.1109/icaccp.2019.8883007. [5] walica, p. n. d. (2020). “design and realisation of the simulation model of the stewart platform using the matlabsimulink and the simscape multibody library”. 2020 21th international carpathian control conference (iccc). [6] haidar, a. m. a., benachaiba, c., & zahir, m. 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[11] g. adel, a. iop, c. ser, m. sci, and g. a. aziz, “stability control investigation of a self-balancing platform on the robot smart car using navigation parameters stability control investigation of a self-balancing platform on the robot smart car using navigation parameters,” 2020, doi: 10.1088/1757-899x/765/1/012066. [12] m. alkhedher, u. ali, and o. mohamad, “modeling, simulation and design of adaptive 6dof vehicle stabilizer,” 2019 8th int. conf. model. simul. appl. optim. icmsao 2019, pp. 6–9, 2019, doi: 10.1109/icmsao.2019.8880417. [13] r. chen, y. ou, w. fang, y. shi, and l. liu, “simulation analysis of a self-balancing hydraulic platform for agricultural machinery in mountainous regions,” j. eur. des syst. autom., vol. 53, no. 2, pp. 203–211, 2020, doi: 10.18280/jesa.530206. [14] thomas, n., & poongodi, p. (20١9). “position control of dc motor using genetic algorithm based pid controller”. proceedings of the world congress on engineering 2009 vol ii. 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[23] munadi and m. a. akbar, “simulation of fuzzy logic control for dc servo motor using arduino based on matlab/simulink,” proc. 2014 int. conf. intell. auton. agents, networks syst. ina. 2014, pp. 42–46, 2015, doi: 10.1109/inagentsys.2014.7005723. [24] giacotto, a. (2019). “matlabsimscape multibody model based simulation for mechatronic systems”. m.sc. thesis, mechatronics engineering, polytechnic university of turin. italy. [25] a. n. barakat, k. a. gouda, and k. a. bozed, “kinematics analysis and simulation of a robotic arm using matlab,” alkhwarizmi eng. j., vol. 15, no. 1, pp. 10–22, 2017, doi: 10.1109/ceit.2016.7929032. [26] meena, d., k. & chahar, s. (2017). “speed control of dc servo motor using genetic algorithm”. ieee.international conference on information, communication, instrumentation and control (icicic).doi:10.1109/icomicon.2017.827 9122. ����� �� )2021( 2944 ! �� ، 3ا���د ،17ا����� ا������� ا���ارز�� ���� ��ى 44 ��(� ذا��� ا�%�ازن �& �� رة ا��%�$���� # ة ����� �� **� ھ� +��& ���م * ��ى ***ا/�� ���وس ***،**،*��� 9 .8% 67'اد /34!% ھ)'&% ا#12ارز./ ,+* ھ)'&% ا#"!� ��و * -� bushra.a.tawfeeq@gmail.com:ا#=�>' ا;#�:�و ** :-� drmahir@kecbu.uobaghdad.edu.iqا#=�>' ا;#�:�و -� ahmed78@kecbu.uobaghdad.edu.iq:*** ا#=�>' ا;#�:�و ا��0!� � ا#"�hً1!i d!ji ;&:2'ا.e fاd. 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'<'8# &!) ر>1ھ ت ا`?�ا7 ت ا#?�>e gا#"1jر ا#+!)أو ا#"1jر ا#o دي أو 4^ ا#"1jر>d (زوا> ا;�j'ار و �: rs ا#"j 4 ة إ#x أن ا#")o% أp3"4 ا#:+ �!k� .*�j:#اب ا�� ا;`?!ab� pj� %!�اn#در9% ١٠و در9% ١٠(1>% اx3h ( دي o#1ر اj"#1ر ا#+!)واj"#ا d. @,أ -e d<1رj"#٢و4^ ا %!� a -3. ح�:c"#ا�اn#ا#:1ازن ا %o("# 4 ة j"#1ذج ا"�>:": %,'7 x�h %<1+ #!% و>3=ا#":?3= ت ا#:we ،v#n# . x3h %!3!6kن y!+=#ا z"!"o� d. *{� .ا# this is an open access article under the cc by license : systematic review of image segmentation programs in craniomaxillofacial surgery khawla h. rasheed1*, auns qusai al-neami2, and haider abdul raheem abbas3 1college of dentidstry, ibn sina university of medical and pharmaceutical sciences, baghdad, iraq 2 department of biomedical engineering, college of engineering, al-nahrain university, baghdad, iraq 3department of oral and maxillofacial surgery, ghazi al hariri hospital, medical city, baghdad, iraq *corresponding author’s email: eng.khawlarasheed@gmail.com (received 21 january 2024; revised 21 april 2024; accepted 4 november 2024; published 1 june 2025) https://doi.org/10.22153/kej.2025.11.001 abstract image segmentation has a significant role in the virtual planning, execution, and evaluation of craniomaxillofacial (cmf) surgical procedures. this systematic review aims to evaluate and compare the image segmentation programs frequently used in the field of cmf surgery. a precise search strategy was employed to recognise suitable studies across several databases, using specific inclusion criteria and keywords. various image segmentation programs that use different techniques, including thresholding, edge-based methods, region-based methods and machine learning-based methods, were investigated. results were screened through preferred reporting items for systematic reviews and meta-analyses. a total of 94 reports on the use of virtual surgical planning from january 1, 2014, to june 1, 2023, were obtained. the identified image segmentation programs were analysed, including factors such as program features, strengths, limitations, supported image modalities, and clinical applications. a qualified assessment of these programs was conducted on the basis of parameters such as segmentation accuracy, processing speed, robustness, user-friendliness and integration capabilities. the review also addresses challenges faced by current segmentation programs and outlines future directions for advancement, including the standardised validation metrics and the integration of artificial intelligence. surgical procedures were assigned into seven categories for analysis: cranial reconstructions, facial rejuvenation, orthognathic surgery, trauma repair, tumour resection, cleft lip and palate and patient specific implant. amongst the software that could be used for bone segmentation in cmf region, eight software programs are most frequently used. results showed that the materialise suite was the most widespread tool for bone segmentation programs, with a prevalence of 50%, followed by the 3d slicer. this review underlines the principal significance of image segmentation in cmf surgery and offers valuable insights for clinicians and researchers to make informed decisions regarding the selection and utilisation of image segmentation programs. keywords: image segmentation; craniomaxillofacial surgery; surgical planning; segmentation programs; medical imaging; computer-aided surgery; image analysis; surgical navigation. 1. introduction software plays an integral role in the diagnosis and treatment of patients; this role is like that of many medical or surgical devices. craniomaxillofacial (cmf) surgery, a specialised field within the broader domain of surgical interventions, involves sophisticated procedures aimed at addressing a wide array of cmf pathologies, including trauma, al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 21, no. 2, june (2025), pp. 12-22 mailto:eng.khawlarasheed@gmail.com https://doi.org/10.22153/kej.2025.11.001 khawla h. rasheed al-khwarizmi engineering journal, vol. 21, no.2, pp. 1222 (2025) 13 congenital anomalies and tumours [1]. the precision and effectiveness of such surgeries are considerably influenced by the details provided by medical images, particularly in the context of image segmentation. image segmentation is the process of dividing medical images into distinct anatomical regions of interest, which are crucial in cmf surgery. it has an important role in surgical planning, intraoperative navigation, and outcome assessment [2]. literature provides acceptable evidence that image segmentation and virtual surgical planning have remarkable effect on the accuracy of bone cutting. this progression helps divide and reconstruct the craniofacial skeleton, with a focus on compatibility and a proper fit of anatomical parts; it has also allowed the design of patient-specific implants that are personalised to the individual morphological variations of each patient [3–5]. virtual surgical planning is an important development in the field of craniofacial surgery, where it enhances the accuracy of preoperative planning, possibly resulting in more accurate reconstructions. in other words, it may significantly reduce operating time, increase clinical and patient outcomes, and increase surgical efficiency by planning the operations. the development of medical imaging techniques like computed tomography (ct) and magnetic resonance imaging (mri) has led to an increase in the need for automated and semi-automated image analysis approaches. thus, various segmentation methods, such as thresholding, region-based methods, edge-based methods and machine learning-based methods, were developed [6]. these techniques facilitate defining pathological regions, outlining and detecting critical structures and easing threedimensional reconstruction that improves surgeons’ understanding of complex anatomical structures [7]. the integration of specialised software capable of effective and precise image segmentation has become essential in modern cmf surgical practice [8]. simulated surgical scenarios using virtual and augmented reality technologies have been widely used in cmf surgery. these tools help surgeons practice complex surgical procedures in a virtual environment before performing them. surgeons can receive feedback during surgery by using these technologies, where computer graphics are used to import geometric data taken from volumetric imaging of patients, such as ct and mri [9]. in cmf surgery, these programs are used in any step of the digital workflow, including segmentation of required structures, reconstruction of three-dimensional models and creation of implants or structures that are ready for printing [10]. these programs could be used to simulate surgical planning of osteotomies and soft tissue, design surgical guides and moulds, create implantable prosthetic devices and evaluate distance and angle measurements [11–14]. 1.1. image segmentation techniques in cmf surgery many segmentation techniques are used in medical image segmentation, which is an important step in modern cmf surgery. they improve the understanding of anatomical structures and many pathological cases. these techniques have been used to detect and segment regions of interest. the most frequently used techniques are thresholding, regionbased methods, edge-based methods and machine learning-based methods. thresholding is a technique where pixel intensity values are utilised to differentiate between different adjacent regions [15]. this method is very useful when dealing with images that have distinct intensity peaks. in cmf surgery, thresholding is mostly used to segment bone from soft tissues. however, it is not very efficient in cases of presence of variations in tissue intensity due to noise, artifacts or anatomical abnormalities [16, 17]. an image is segmented into regions on the basis of predetermined characteristics such as texture or intensity. this step most frequently performed using watershed and region-growing segmentation methods. in cmf surgery, region-based methods can help improve the segmentation of complex structures with varying densities or images with lower contrast that do not have distinct differences in densities and variations between adjacent structures such as tumours or vascular structures. although these techniques are sensitive to the original seed points, the parameters may have to be fine-tuned because of their ability to identify minute nuances [18]. the edge-based technique relies on detecting boundaries between different adjacent structures by khawla h. rasheed al-khwarizmi engineering journal, vol. 21, no.2, pp. 1222 (2025) 14 detecting abrupt changes in pixel intensity [19]. techniques like canny edge detector is manipulated to help outline structures that have well-defined edges or boundaries, such as blood vessels or bones. however, identifying edges or contours in low-contrast images can be difficult, leading to some mistakes in boundary detection [20]. machine learning, particularly convolutional neural networks, has become increasingly important in many areas of modern life, especially in the segmentation of medical images, due to its ability to learn complex patterns from a large number of datasets. machine learning shows great promise in cmf surgery for segmenting anatomical features and abnormalities. it can be applied across varying anatomical features and adapted to the differences among patients, but this method requires extensive training data and significant computational resources. in addition, the decision-making process may not be transparent [21, 22]. whilst each of these segmentation techniques has several benefits and drawbacks, their applicability varies depending on a number of variables, including surgical scenarios and image quality. as a result, these methods rely on the case, the level of accuracy needed and the available computational resources. the available literature does not provide a comprehensive review of all image segmentation software used in cmf surgery. comparative studies that assessed the performance of various segmentation techniques in this region and the rapid technological advancements are lacking. this study aimed to fill this gap by systematically reviewing a wider range of segmentation methods and comparing the available programs’ features, strengths and limitations, thus allowing for identification of areas of improvement [23]. this review aimed to provide clinicians, researchers, and other healthcare professionals who specialised in the craniofacial region a comprehensive understanding of segmentation programs, including their features, strengths, limitations and possible effects on clinical practice. by analysing the features of the current segmentation programs, this review aimed to illustrate their clinical usefulness, evaluate their performance and outline their capability for further advancements in this critical aspect of virtual surgical planning and implementation. 2. methodology 2.1. search strategy electronic databases like pubmed, scopus, ieee xplore, and web of science were investigated. a combination of free-text and medical subject headings (mesh) terms was employed in the search. ‘surgical planning’, ‘image segmentation’, ‘craniomaxillofacial surgery’ and ‘segmentation programs’ were amongst the terms mentioned. the search period was restricted from january 1, 2014, to june 1, 2023. 2.2. criteria for inclusion and exclusion all articles included in this study were checked for eligibility and duplicates, and all titles and abstracts were scanned for suitability by two independent reviewers. the inclusion criteria consisted of articles published between january 1, 2014, and june 1, 2023. a specific exclusion criterion was applied. thus, this work focused on bone segmentation performed on the cmf region for surgical purposes. studies that reported on original research or case studies addressing the use of image segmentation programs in cmf surgery and provided a thorough explanation of the segmentation program’s results were included. articles in english and those involving ct imaging modality were included. studies were excluded if they were review articles, conference abstracts or editorials. 2.3. study selection in the initial search, a total of 1940 articles were detected. two independent reviewers screened the titles and abstracts to identify potentially relevant studies [24]. the full texts of these articles were then evaluated to determine their appropriateness for this study on the basis of the predetermined inclusion and exclusion criteria. any discrepancies were discussed and resolved through discussion and consensus. khawla h. rasheed al-khwarizmi engineering journal, vol. 21, no.2, pp. 1222 (2025) 15 fig. 1. prisma flowchart for article selection 2.4. data extraction and synthesis from the selected studies, a standardised data extraction method was developed and used to extract appropriate information. the extracted data involved details about the segmentation programs, anatomical regions studied, image modalities, segmentation techniques employed, outcome measures and reported results to provide a comprehensive understanding of the classifications for individual procedures within the context of cmf surgery. table 1 outlines various categories and their respective surgical procedures as a guide to understand the scope of this review. the data collection involved a qualitative analysis of the included studies, focusing on the programs’ features, limitations, strengths and clinical applications. 3. results and discussion comparing the performance and features of different segmentation programs is important for medical professionals and scholars to make subjective choices regarding their selection. different programs were assessed in accordance with the key components necessary for their successful utilisation in cmf surgery. khawla h. rasheed al-khwarizmi engineering journal, vol. 21, no.2, pp. 1222 (2025) 16 table 1, definitions outlining the classifications for individual procedures category definition surgical procedures cranial reconstructions surgical procedures involving the restoration and reshaping of the cranial vault to address congenital anomalies, trauma, or tumours cranioplasty and fronto-orbital advancement facial rejuvenation surgical interventions addressing fractures and injuries of the facial bones caused by trauma. facelift, blepharoplasty, and brow lift orthognathic surgery surgical corrections of skeletal discrepancies in the jaw, aiming to improve functional and aesthetic harmony. maxillary osteotomy and mandibular osteotomy trauma repair surgical interventions addressing fractures and injuries of the facial bones caused by trauma. zygomaticomaxillary complex repair and nasal fracture reduction tumour resection procedures targeting the removal of benign or malignant tumours affecting the craniofacial region. mandibulectomy and maxillectomy cleft lip and palate surgical interventions addressing congenital cleft lip and palate anomalies for improved function and appearance. lip repair and palate repair patient-specific implant procedures involving the design and placement of custom implants tailored to a patient’s unique craniofacial anatomy. craniomaxillofacial implant placement 3.1. prevalence of different software packages amongst the software packages analysed in the selected studies, mimics by materialise was the most frequently utilised, appearing in approximately 25 papers, which is approximately 26.6% of the total. following closely was proplan cmf, also by materialise, which was cited in 20 papers (21.2%). the 3d slicer from harvard university had a strong presence in 18 papers ( 19.2%). dolphin by dolphin imaging and management solutions was the software of choice in nine papers (9.6%), followed by the geomagic family from 3d systems, with eight papers referencing it (8.5%). amira was mentioned in four papers (4.3%), rhino3d medical was mentioned in four papers (4.3%) and mevislab was mentioned in two papers (2.1%). these percentages from highest to lowest represent the frequency of use to segment cmf bones in papers included in this review. various software packages were referenced, and they were categorised as distinct and less commonly reported category because each had fewer than one or two references. the frequency of use of the most common segmentation programs is displayed in figure 2. on the one hand, no software was considered better or more accurate when it had a higher mention rate in the research area. on the other hand, the higher percentage could reflect more useful features or better compatibility with specific tasks. fig. 2. prevalence of different software packages. khawla h. rasheed al-khwarizmi engineering journal, vol. 21, no.2, pp. 1222 (2025) 17 3.1. usefulness of different segmentation software packages comparing the features and performance of several segmentation programs is essential for physicians and researchers to make well-informed decisions on which segmentation software to use. as shown in table 2, various programs were evaluated on the basis of key factors mentioned in the reviewed articles. for each factor, a performance satisfaction of above 80% was assumed to be high, moderate if the satisfaction was 50%–80% and variable if the performance ranged between 30% and 50%. these factors are essential for their effective utilisation in cmf surgery. the first and most important criterion is the accuracy of image segmentation, which is an essential feature in medical image analysis and segmentation. it contributes to the success of the following procedures: mimics by materialise is based on thresholding, region growing and manual segmentation. proplan cmf by materialise uses similar techniques as mimics but it is adapted specifically for cmf applications. the 3d slicer uses various segmentation algorithms such as thresholding, region growing, and edge-based methods. it also allows integration of machine learning models for segmentation tasks, allowing for advanced and automated segmentation. the dolphin by dolphin imaging and management solutions uses techniques like thresholding and manual segmentation. the geomagic family from 3d systems combines thresholding, edge detection, and manual segmentation for accurate 3d reconstruction and modelling. in general, these software applications often use a combination of image segmentation techniques, targeted to the specific needs of their respective fields. they may also integrate machine learning or artificial intelligence (ai)-based algorithms for more automated, precise and efficient segmentation processes. the choice of technique can depend on factors like the type of imaging modality, the anatomical structures of interest and the required level of accuracy and detail needed [25–27]. real-time applications depend on programs with good processing capabilities. an ai-based medical segmentation software can improve efficiency, reduce scan time and patient dose and provide accurate and fast results in various medical imaging applications. programs like mimics, rhino and relus offer interactive processing, enabling surgeons for immediate segmentations adjustment [28–89]. user-friendliness is a very important feature, especially in intraoperative intervention. programs like mimics, proplan cmf, 3d slicer and geomagic family make intuitive interfaces a priority that enables users to interact with functions and criteria available in segmentation programs [30, 31]. user-friendliness lowers the requirement for training health professionals and makes products easier to use. amira, mevislab and rhino3d medical are some of the platforms that, albeit having a larger toolbox, could take some extra time and effort for users to become experts with using them [32]. one of the most crucial requirements for any segmentation technique is its ability to effectively handle noise and artifacts, guaranteeing accurate segmentations from defective images. ai-driven programs, such as relu virtual patient creator, are designed to handle noisy input and are less affected by artifacts, but this method may lead to some issues in precision and accuracy, where it depends on readylearning anatomical templates. programs, such as materialise mimics, proplan cmf, and 3d slicer, may offer filtering and correction options to resolve the effects of noise and artifacts [33, 34]. integration with other medical segmentation software enhances the program’s workflow and makes it easier to use. programs, such as mimics, proplan cmf, geomagic studio and geomagic freeform, offer options to export 3d models to be employed on other platforms. open-source platforms, such as 3d slicer, enable the development and modification of custom workflows, thereby improving compatibility with available tools [35, 36]. accessibility and cost play a significant role, especially for institutions that have limited budgets, researchers and students. open-source platforms like 3d slicer offer cost-effective solutions with many capabilities. commercial programs like mimics, proplan cmf, geomagic studio, geomagic freeform and dolphin may provide a wide variety of features but at a higher cost. although each program is superior in certain aspects, the final decision depends on the specific clinical needs; the existing resources; and the desired balance amongst speed, accuracy, ease of use and cost consistency. khawla h. rasheed al-khwarizmi engineering journal, vol. 21, no.2, pp. 1222 (2025) 18 table 2, evaluation of various programs based on key factors essential for their effective utilisation in craniomaxillofacial surgery. 4. conclusion despite progress in image segmentation programs for cmf surgery, several challenges and limitations 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( 2025) 22-21، صفحة 2، العدد12مجلة الخوارزمي الهندسية المجلد خولة حميد رشيد 22 مراجعة منهجية لبرامج تقسيم الصور في جراحة الوجه والفكين 3حيدر عبد الرحيم عباس , 2أنس قصي النعيمي, *1خولة حميد رشيد 1كلية طب االسنان، جامعة ابن سينا للعلوم الطبية و الصيدالنية ، بغداد ، العراق 2 هندسة الطب الحياتي ، كلية الهندسة، جامعة النهرين, بغداد ، العراق 3 قسم جراحة الوجه والفكين، مستشفى الشهيد غازي للجراحات التخصصية ، مدينة الطب ، بغداد ، العراق eng.khawlarasheed@gmail.com :البريد االلكتروني* المستخلص المراجعة المنهجية إلى يلعب تقسيم الصور دوًرا مهًما في التخطيط االفتراضي والتنفيذ وتقييم اإلجراءات الجراحية في مجال جراحة الوجه الفكين. تهدف هذه بر عدة قواعد بيانات، باستخدام تقييم ومقارنة برامج تقسيم الصور المستخدمة بشكل متكرر في هذا المجال. تم اعتماد استراتيجية بحث دقيقة لتحديد الدراسات المناسبة ع ، (thresholding) تعتمد على تقنيات مختلفة، مثل تقنيات تحديد العتبات معايير إدراج محددة وكلمات مفتاحية ذات صلة. تم التحقيق في برامج تقسيم الصور التي .، باإلضافة إلى الطرق القائمة على التعلم اآللي(region-based methods) ، وطرق تحديد المناطق( edge-based methods) وطرق تحديد الحواف دراسة تقرر اختيار الدراسات 94، حيث تم تحديد (prisma) "تم فحص النتائج وفقًا لبيان "عناصر التقرير المفضلة للمراجعات المنهجية والتحليالت التلوية . أجريت دراسة تحليلية لبرامج تقسيم الصور المحددة، مع التركيز 2023يونيو 1و 2014يناير 1التي استخدمت التخطيط الجراحي االفتراضي في الفترة ما بين ت السريرية. تم إجراء تقييم مؤهل لهذه البرامج بناًء على معايير مثل دقة التقسيم، سرعة على ميزات البرامج ونقاط القوة والضعف وأنواع الصور المدعومة والتطبيقا المعالجة، الصالبة، سهولة االستخدام وقدرات التكامل مع البرامج األخرى. القياسية ودمج الذكاء االصطناعي. تناقش المراجعة أيًضا التحديات التي تواجهها برامج التقسيم الحالية وتحدد اتجاهات التطوير المستقبلية، بما في ذلك معايير التحقق استئصال األورام، إصالح تم تقسيم اإلجراءات الجراحية إلى سبع فئات لتحليلها، وهي: إعادة بناء الجمجمة، تجديد الوجه، جراحة تقويم الفكين، إصالح اإلصابات، توجد العديد من البرامج التي يمكن استخدامها لتقسيم العظام في منطقة الفكين والوجه، إال أن هناك ثمانية .الشفة األرنبية والحنك، وتصميم زراعة مخصصة للمريض 3d“، تليها أداة %50هي األداة األكثر انتشاًرا لتقسيم العظام بنسبة "materialise"برامج تُعد األكثر استخداًما في هذا المجال. أظهرت النتائج أن حزمة برامج slicer” ة بشأن المراجعة الضوء على األهمية األساسية لتقسيم الصور في جراحة الفكين والوجه وتقدم رؤى قيمة لألطباء والباحثين التخاذ قرارات مستنيرتسلط هذه .اختيار واستخدام برامج تقسيم الصور mailto:eng.khawlarasheed@gmail.com this is an open access article under the cc by license : al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 21, no. 4, december, (2025), pp. 3244 preparation and characterisation of activated carbon from pomegranate waste using chemical with microwave activation ali a. hanoon1 and sami d. salman2* 1,2 department of biochemical engineering, al-khwarizmi college of engineering, university of baghdad, baghdad, iraq *corresponding author’s e-mail: sami@kecbu.uobaghdad.edu.iqm (received 18 september 2024; revised 27 october 2024; accepted 24 november 2024; published 1 december 2025) https://doi.org/10.22153/kej.2025.11.005 abstract this study presents the preparation method and characterisation of activated carbon (ac) from pomegranate waste by using chemical with microwave activation. pomegranate peels in powder form were impregnated in 40–60 %wt sulphuric acid with different ratios (1:3 of pomegranate to sulphuric acid) and times (2–6 h) for chemical activation. the impregnated samples were activated in microwave under inert atmosphere at different powers (450–900 w) and activation times (7–21 min) to produce ac. design-expert software (version 13) was selected with the i-optimal method to analyse the effects of ac preparation variables. the preparation variables, including acid concentration, impregnation time, impregnation ratio, microwave power and activation time, with their effects on the adsorption capacity of methylene blue dye, were investigated. on the basis of the obtained maximum methylene blue number, the ac and raw material were characterised via brunauer–emmett–teller test, field emission scanning electron microscopy with energy-dispersive xray analysis, fourier transform infrared spectroscopy and x-ray diffraction analysis. results indicate that the ac produced from pomegranate peels achieves a sufficient surface area of 1431.8 m2/g and a total pore volume of 1.6236 cm3/g with a spongy and amorphous nature with minor crystal characteristics. it can be used as a low-cost product with desirable surface characteristics. these results promote the use of ac prepared from pomegranate waste as an obtainable and lowcost adsorbent. keywords: pomegranate peels; activated carbon; sulphuric acid; microwave activation 1. introduction activated carbon (ac) is a material that is similar to black charcoal; it exhibits a good pore structure and high surface area with significant mechanical durability [1]. ac is widely used in different applications, such as gas cleaning and separation [2], water purification [3-5], industrial effluent treatment [6-9] and pharmaceutical [10], catalyst, supercapacitor and electrode [11] applications. ac is popular because of its versatility in adsorbing various types of contaminants that range from dyes [4, 5, 8, 12], heavy metals [3, 6, 13], phenolic compounds [14], antibiotics [10], hydrogen sulphide [15] and carbon dioxide [16]. ac derived from agricultural by-products is a viable and affordable substitute for conventional ac derived from hardwood or petroleum-based sources. agricultural by-products are widely accessible and abundant, making them desirable as raw materials for the manufacture of ac. given its high adsorption capacity, ac has a substantial specific surface area, i.e., the total surface area of a material per unit of mass. considering its large surface area, ac can be applied to processes, such as adsorption, which involves the removal of contaminants from gases or liquids. [17]. these mailto:sami@kecbu.uobaghdad.edu.iqm https://doi.org/10.22153/kej.2025.11.005 ali a. hanoon al-khwarizmi engineering journal, vol. 21, no.4, pp. 3244 (2025) 33 properties are significantly affected by raw material selection, activation process and activating substance [18]. therefore, many researchers have investigated ac production from a variety of organic materials that are affordable and sustainable precursors, such as alhagi [14], buckthorn twigs [19], plum seed [6], water hyacinth [20], saw dust [3, 21], cycas leaves [12], apricot seeds [10], date palm seeds and fronds [8, 22], date stones [23, 24], orange peel [25], cassava peel [26], banana peel [27], garlic peel [28], potato peel [29], waste tea [30, 31], rice husk [32], walnut shell [33], oil palm fibre [34] and coconut shell [35]. pomegranate is one of the most well-known fruits due to its rich nutritional contents and delicious flavour. it has peel and internal edible seeds. pomegranate peel is a nonedible part that comprises about 5%–15% of its weight; it is considered a waste product without commercial benefits [36]. pomegranate peel is a low-cost and eco-friendly precursor that can be used for ac preparation; the produced ac can be utilised to remove pollutants from gases and aqueous solutions [37-40]. the preparation of ac from various precursors can be conducted using physical and chemical activation techniques. physical activation is performed in two stages. the first stage comprises the pyrolysis process of the carbonaceous material; the second stage involves gasification with oxidant agents, such as co2, steam or a combination of co2 and steam, at high temperatures [41, 42]. chemical activation is achieved by impregnating a carbonaceous material with different chemical agents, followed by either conventional or microwave carbonisation [43, 44]. chemical activation necessitates the use of activating agents, such as sulphuric acid [6, 45], phosphoric acid [4, 10, 19, 29], zinc chloride [46-48] potassium carbonate [49] and potassium hydroxide [14]. microwave carbonisation is preferred due to its heating method (low temperature), lower gas consumption, shorter carbonisation time, higher productivity and higher product specification (surface area, pore diameter and pore volume) [50]. however, conventional heating or carbonisation is performed using a conventional furnace, which requires high temperature with a long period of heating (high energy consumption) [18]. in this regard, microwave is a renewable alternative to conventional carbonisation [51]. given its many benefits over conventional heating methods, the use of microwave in the synthesis of ac is garnering growing study interest. its benefits include an internal heating rate, a high heating rate, selective heating, effective process regulation, short heating time that results in lower energy consumption and indirect contact with the heat source [10, 29, 52]. in addition, microwave heating creates a uniform temperature distribution, reducing the temperature gradient in the material and leading to the uniformity of pore size [50]. the objective of the current research is to prepare ac by using pomegranate peels as a natural and low-cost source and microwave activation as an efficient technique for preparation. the effects of the parameters and conditions for preparation, including impregnation ratio (ir), activation energy and activation time, on the specific surface are investigated to achieve optimum conditions. fourier transform infrared (ftir) spectroscopy, scanning electron microscopy (sem) with energy-dispersive x-ray (edx) analysis and brunauer–emmett– teller (bet) test are used for the characterisation of pomegranate peels and the ac produced under optimum conditions. 2. materials and methods 2.1. preparation of ac pomegranate peels were collected from a local plantation area in baghdad. firstly, the pomegranate peels were chopped to 1–2 cm pieces, washed with plenty of water to clean dirt and then dried for 4 h at 105 °c by using an air dryer. the dried material was crushed and sieved to the required size (2 mm). the sample (approximately 20 g) was impregnated into sulphuric acid (40–80 wt%) for 2–6 h at room temperature with different irs: 1–3. then, the samples were filtered to remove excess acid from each and the microwave method was used for ac preparation [4]. each sample was poured into a flask and fixed in a microwave oven under a nitrogen flow of 200 cm3/min at different activation levels (450–900 w) and activation times (7–21 min). after activation, the samples were allowed to cool under nitrogen atmosphere. the final product was washed with hot water and filtered until its ph reached 6–7. finally, the product was dried at 105 °c for 4 h, pulverised and sieved to the required size range. the schematic of the ac preparation steps is presented in figure 1. ali a. hanoon al-khwarizmi engineering journal, vol. 21, no.4, pp. 3244 (2025) 34 fig. 1. schematic of ac preparation from pomegranate peels 2.2. methylene blue test methylene blue dye powder was used to prepare methylene blue stock solution (50 mg/l) by dissolving 50 mg of the powder in 1 l of distilled water. ten flasks (10 cm3) were used to prepare samples with the desired concentrations of 0.025, 0.05, 0.1, 0.2, 0.4, 0.5, 0.8, 1, 2 and 4 mg/l [7]. ultraviolet–visible (uv–vis) spectroscopy (wavelength = 660 nm) was used for the calibration curve, as shown in figure 2. to determine the concentration after adsorption, 0.1 g of each of the prepared ac sample was shaken for 60 min with 50 ml of stock solution. absorbance was measured via uv–vis spectroscopy at wavelength λ = 660 nm. adsorption capacity, given as methylene blue number (mbn), was calculated using equation 1. 𝑀𝐵𝑁 = (𝐶𝑜−𝐶𝑒)𝑉 w , …(1) where 𝐶𝑜 is the initial concentration (mg/l), 𝐶𝑒 is the equilibrium concentration (mg/l), mbn is the adsorption capacity of the dye to ac weight (g/g), v is the volume of the dye sample (ml), w is the ac weight (g). fig. 2. methylene blue calibration curve 3. experimental design design-expert software (version 13.0) is a helpful statistical programme for creating models and designing experiments by considering the interactions amongst different parameters. the effects of acid concentration, ir with impregnation time and microwave power with activation time as independent variables on methylene blue dye adsorption capacity were investigated using the ioptimal method, as indicated in tables 1 and 2. table 1, independent variables of ac preparation symbol variables level a acid concentration (%) 40 60 80 b ir (ratio) 1:1 1:2 1:3 c impregnation time (h) 2 4 6 d activation power (w) 450 720 900 e activation time (min) 7 14 21 ali a. hanoon al-khwarizmi engineering journal, vol. 21, no.4, pp. 3244 (2025) 35 table 2, design-expert variables and results by using the i-optimal method run a: concentratio n b:ir c: impregnation time d: power e: activation time mbn # % ratio h w min g/g 1 80 3 4 720 7 24.713247 2 40 3 6 450 7 24.356002 3 40 1 2 900 7 25.13029 4 80 1 6 450 21 25.18612 5 80 1 6 900 7 25.126254 6 40 1 6 900 7 25.05159 7 60 1 4 720 14 25.120873 8 60 1 4 720 14 24.964818 9 40 1 2 450 21 24.804054 10 80 1 2 900 14 24.928629 11 60 3 6 900 14 23.626244 12 80 2 6 450 7 24.938584 13 40 2 4 720 14 24.904952 14 60 3 6 450 21 25.198227 15 40 3 2 900 21 23.677366 16 60 3 2 450 14 24.103826 17 80 1 2 450 7 24.520869 18 60 2 4 900 7 24.376922 19 40 2 4 720 14 25.188138 20 40 1 6 450 14 25.188138 21 40 1 6 900 21 24.522887 22 80 2 4 900 21 23.090949 23 80 2 2 720 21 24.524905 24 40 1 2 450 7 23.678711 25 60 2 4 900 7 24.574008 26 60 2 2 720 7 25.18612 27 60 1 4 720 14 25.079841 28 40 3 4 720 7 24.524232 29 80 3 2 900 14 23.694182 30 40 3 4 450 14 24.470353 4. results and discussion 4.1. bet test table 2 clearly shows that the ac sample (run number 14) produce the maximum mbn value, indicating that this sample achieves the maximum specific surface area and pore volume. the bet technique (horiba, sa-900 series, usa) was selected to estimate the specific surface area, average pore diameter and pore volume based on the liquid nitrogen adsorption–desorption method at an adsorption temperature of 77 k, saturated vapor pressure of 86.75 kpa and adsorption cross-section area of 0.162 nm2. the results are provided in table 3. the specific surface area, average pore diameter and pore volume of pomegranate peels were 8.9671 m2/g, 5.6405 nm and 0.012645 cm3/g, respectively. meanwhile, the specific surface area, average pore diameter and pore volume of ac increased to 1431.8 m2/g, 2.5934 nm and 1.623601 cm3/g, respectively. table 3, bet test for the raw material and ac samples surface area [m2/g] average pore diameter [nm] total pore volume (p/p0 = 0.990) [cm3/g] pomegranate peel 8.9671 5.6405 0.012645 ac 1431.8 2.5934 1.623601 ali a. hanoon al-khwarizmi engineering journal, vol. 21, no.4, pp. 3244 (2025) 36 4.2. field emission sem (fesem) and edx analysis to investigate the morphological surface and elemental species composition of pomegranate peels and ac, fesem with edx analysis was conducted, and the results are presented in figures 3–6 and tables 4 and 5. as shown in figure 3, the pomegranate peels exhibit a homogenous surface, large pore diameter and low pore volume. meanwhile, figure 4 shows a spongy surface with many porous structures and pores with different volumes and shapes. this finding is attributed to the decomposition and volatilisation of noncarbonaceous substances in pomegranate peels due to chemical and microwave activation. in addition, the edx spectra of pomegranate peels and ac exhibit an evident variation in their elemental composition due to chemical and microwave activation, as shown in figures 5 and 6 and tables 4 and 5. these tables indicate that the carbon content of pomegranate peels is increased from 38.6% to 74.5% for ac due to the carbonisation and activation processes. consequently, their elemental compositions were changed. fig. 3. images of pomegranate peels fig. 4. images of ac fig. 5. edx spectroscopy of pomegranate peels ali a. hanoon al-khwarizmi engineering journal, vol. 21, no.4, pp. 3244 (2025) 37 fig. 6. edx spectroscopy of ac table 4, composition of pomegranate peels element atomic % atomic % error weight % weight % error c 46.2 0.3 38.6 0.3 o 52.8 0.4 58.8 0.4 cl 0.2 0.0 0.5 0.0 k 0.6 0.0 1.5 0.0 ca 0.2 0.0 0.5 0.0 table 5, composition of ac element atomic % atomic % error weight % weight % error c 72.8 0.4 74.5 0.4 o 25.4 0.5 20.3 0.6 al 0.4 0.0 0.7 0.1 k 0.8 0.0 2.1 0.1 ca 0.4 0.0 1.2 0.0 fe 0.1 0.0 0.5 0.1 nb 0.1 0.1 0.7 0.6 5. ftir analysis the ftir analysis spectra of the pomegranate peels (pp) and ac (ppac) between the wavelengths of 4000 cm−1 and 500 cm−1 are shown in figure 7. the raw materials have different peaks, reflecting their complex properties. the peaks between 3000 cm−1 and 3500 cm−1 indicate the oh stretching of alcohols, phenols and carboxylic acids [53, 54]. similarly, the peaks between 2500 cm−1 and 3000 cm−1 are denoted by the c-h group [55]. meanwhile, the spikes between 1000 cm−1 and 1500 cm−1 refer to phenolic c=c and aldehydic c=o, whilst the peaks between 500 cm−1 and 1000 cm−1 indicate aromatic chemicals [56, 57]. furthermore, the peaks appeared due to the formation of a new bond during chemical and microwave activation. consequently, the peaks around 3000 cm−1 and 3500 cm−1 indicate the oh stretching of alcohols, phenols and carboxylic acids [53, 54]. similarly, the peaks between 2500 cm−1 and 3000 cm−1 are indicated by c-h bending stretching [55, 58]. the peaks between 1500 cm−1 and 1750 cm−1 are mostly signified by alkene c-c and ketone c=o. conversely, the peaks around 1000 cm−1 and 1300 cm− 1 are assigned to co bonds due to the existence of of hydroxy and esters. similarly, the peaks between 600 cm−1 and 900 cm− 1 are assigned to = c-h due to the existence of alkenes [8]. ali a. hanoon al-khwarizmi engineering journal, vol. 21, no.4, pp. 3244 (2025) 38 fig. 7. spectra of pomegranate peels and ac 6. x-ray diffraction (xrd) xrd analysis with a range of 2θ of 10°–80° for pomegranate peels and ac are depicted in figures 8 and 9, respectively. pomegranate peels and ac have amorphous structures. sharp peaks at 2θ of 21.3°, 26.8° and 29.5°, as shown in figure 9, indicate that ac exhibits mostly amorphous characteristics with a minor crystalline structure [59]. fig. 8. xrd profile of pomegranate peels fig. 9. xrd profile of ac ali a. hanoon al-khwarizmi engineering journal, vol. 21, no.4, pp. 3244 (2025) 39 7. conclusion the major results of the current research demonstrated the suitability of ac prepared from pomegranate peels with significant specific surface area, average pore diameter and pore volume via chemical and microwave activation. sulphuric acid with different concentrations (40%–80%) and irs (1–3) was used as an activation agent with different impregnation times (2–6 h), microwave power (450–900 w) and radiation times (7–21 min) to prepare ac. design-expert software (version 13) with the i-optimal method was selected to analyse the ac preparation data. the data were analysed using mbn, and the results showed that sulphuric acid with a concentration of 60%, ir of 1:3, impregnation time of 6 h, microwave power of 450 w and radiation time of 21 min emerged with the highest mbn value. on the basis of the maximum mbn value, which elaborated the maximum specific surface area and pore volume, pomegranate peel and ac samples were selected for characterisation. the results demonstrated that the specific surface area, average pore diameter and pore volume of pomegranate peels were 8.9671 m2/g, 5.6405 nm and 0.012645 cm3/g, respectively. for ac, these parameters were 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[59] s. kasaoka, y. sakata, e. tanaka, and r. naitoh, "preparation of activated fibrous carbon from phenolic fabric and its molecular-sieve properties," int. chem. eng., vol. 29, no. 1, pp. 101-114, 1989. https://doi.org/10.1016/j.jece.2014.03.015 ( 2025) 32-44، صفحة 4، العدد21مجلة الخوارزمي الهندسية المجلد علي عادل حنون 44 تحضير وتوصيف الكربون المنشط من مخلفات الرمان باستخدام طريقة التنشيط الكيميائي والمايكروويف علي عادل حنون1، سامي داوود سلمان2* 2,1 قسم الهندسة الكيميائية األحيائية، كلية الهندسة الخوارزمي، جامعة بغداد، بغداد، العراق sami@kecbu.uobaghdad.edu.iqm*البريد االلكتروني: المستخلص الميكروويف. حيث يتم غمر مسحوق تقنيةيقدم هذا البحث طريقة تحضير وتوصيف الكربون المنشط من قشور الرمان باستخدام التنشيط الكيمياوي مع مختلفة )قشور رمان إلى حامض الكبريتيك( وبأوقات غمر مختلفة. كما تم تنشيط العينات وبنسب وزنيةقشور الرمان بحامض الكبريتيك كعامل تفعيل كيميائي )اإلصدار تصميم التجارب تم اختيار برنامج وأوقات تنشيط مختلفة إلنتاج الكربون المنشط. درةالميكروويف تحت جو خامل بقباستخدام تقنية علة بالحامضفالم باستخدام طريقة13 ) i-optimal الح تركيز ذلك في بما المنشط الكربون متغيرات تحضير تأثير زمنمض التحليل فرن درةوق التفعيلونسبة التفعيل ، ا زمنالميكروويف و تم الحصول تياامتزاز صبغة الميثيلين الزرقاء ناًء على الحد األقصى . ب(mbn)زرقاء صبغة الميثيلين ال متزازالتنشيط على قدرة مع (fesem) يثاالنبعا يمسح اإللكترونال، ومجهر brunaure-emmett-teller (bet)م الكربون المنشط باستخداقشور الرمان و، تم توصيف اعليه الكربون النتائج أن ثبتتأوقد .(xrd) والحيود باألشعة السينية (ftir)الحمراء ، ومطيافية األشعة تحت (edx)للطاقة تحليل األشعة السينية المشتتة المنتج من الرمان المنشط بلورية له قشور أساسي مع خصائص متبلور بشكل الدقيقة فليلة ويمتلك أحجام طبيعة إسفنجية وغير المسام يمكن ومختلفة من .استخدامه كمنتج منخفض التكلفة بخصائص مرغوبة mailto:sami@kecbu.uobaghdad.edu.iqm <4d6963726f736f667420576f7264202d20dac8cf20c7e1d1cde3e420e6cf20ddd1c7ca20e6cf20e3e5e4cf2e2038382d203937> this is an open access article under the cc by license al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 19, no. 3, september, (2023) p. p. 8897 creating a labview sub vi for the ina219 sensor for detecting extremely low-level electrical quantities abdulrahman b. khudhair* furat i.hussein** muhannad ahmed obeidi*** *,** department of mechatronics engineering / al-khwarizmi college of engineering/ university of baghdad/ baghdad/ iraq ***form advanced manufacturing research centre/ school of mechanical and manufacturing engineering/ dublin city university/ dublin/ ireland. corresponding author: *email : abd.basheer2102m@kecbu.uobaghdad.edu.iq furatnejjar@uobaghdad.edu.iq email :** muhannad.ahmedobeidi@dcu.ie email :*** (received 8 february 2023; accepted 8 may 2023) https://doi.org/10.22153/kej.2023.05.001 abstract an impressed current cathodic protection system (iccp) requires measurements of extremely low-level quantities of its electrical characteristics. the current experimental work utilized the adafruit ina219 sensor module for acquiring the values for voltage, current, and power of a default load, which consumes quite low power and simulates an iccp system. the main problem is the adaptation of the ina219 sensor to the labview environment due to the absence of the library of this sensor. this work is devoted to the adaptation of the adafruit ina219 sensor module in the labview environment through creating, developing, and successfully testing a sub vi to be ready for employment in an iccp system. the sensor output was monitored with an arduino uno microcontroller and the labview linx firmware toolkit. pulse width modulation (pwm) technique, which ranges from 0% to 100%, was applied by the arduino to supply the l298n voltage driver in order to regulate the voltage input to the load. a moving average filter was employed to measure the ripple voltage averaging, and a median filter was utilized to stabilize the readings. a passive low-pass filter circuit smoothed the pwm voltage before supplying the load. the results from the matlabsimulink environment showed a cut-off frequency of 2.33 hz, ripple voltage peak to peak was 41.1 mv and a settling time of 0.157 seconds. the calibrated results of the ina219 module sensor showed an absolute voltage inaccuracy of around 2.3% at full scale. in addition, an absolute error in the current of 2.2% at 25 ma shows a gradual increase as the current increases to 7% at 43 ma, while the highest absolute error for the full scale of power was at 5.8%. the obtained measurements were highly precise, and the values of the coefficient of variation were 0.36 %, 0.28% and 0.17% for the voltage, current, and power, respectively. keywords: ina219, labview, sub vi, matlab, low pass filter, l298n. 1. introduction detecting and measuring the characteristics of low-consumption electrical circuits such as current, voltage, and power at extremely low levels has a variety of technical challenges. [1] [2] [3] electrical systems that consume very small power values in the range of milliwatts require the use of sensitive and accurate instruments for that purpose [4]. many techniques were used and are still being used in low-current measurements. the hall-effect-based technique utilizes the generated magnetic field around a conductor in the measurement of passed current. the acs 712 abdulrahman b. khudhair al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 8897 (2023) 89 hall-effect sensor is used to measure current in both (dc) and (ac [5]. another technique utilizes ohm's law by measuring the voltage drop across a resistor of less than 1 ω, called a shunt resistor, in order to measure the current flowing in the circuit. the adafruit ina219 sensor module is used to measure the current flowing in an electrical circuit by reading the voltage drop on the terminals of a 0.1 ω (r100) shunt resistor [6]. many researchers have investigated routes and systems for detecting and monitoring accurate minimal current measurement circuits. kinyua ap et al. [7] utilized the acs712 current sensor to measure the current generated from a tomato after increasing the adc resolution of the icrocontroller from 4.88 mv to detectable low values of 0.83 mv. in that work, the measured current was between 0.002 and 0.05 ma, associated with a little amount of visible noise in the readings. muhammad nizam et al. [8] described the usage of an acs712 current sensor module in monitoring battery consumption. according to the research findings, the precision and accuracy of the current sensor were 64.91% and 83.75%, respectively. h. maghfiroh et al. [9] applied a comparison of multi-meter readings with those of the ina219 current sensor in monitoring the inverter's input current. the study reveals an error of 1.27% as an inaccuracy in sensor readings. afrizal abdi musyafiq et al. [10] utilized the ina219 power sensor to monitor the power output of the pico-hydro power plant, which was reported to be 24.82 mw. at values below 14 ma, the least difference was found to be 0.1 ma, while the highest difference was found to be 1.3 ma. s. h. cheragee et al. [11] utilized an ina 219 current sensor module and a shunt resistance to monitor the generated current from solar pv panels. the maximum and minimum observed current values in specific time intervals are roughly 1 ma and 0.5 ma, respectively. the greatest observed power was 2.5 mw, while the least observed power was approximately 1.5 mw. according to the results of eri wiyadi et al. [12], concerned with the data acquisition of solar module characteristics, ina219 sensor module output showed an error value of 0.76% and a linear correlation with an r-square of 0.98. the ina219's effective detection range was between 10 ma and 3 a. a. t. nugraha et al. [13] utilized the ina219 sensor in their study to measure the current generated as a result of wind energy, and it was able to detect extremely small values of the current around 1.8 milliamps. the motivation of this study is the need for an extremely low current measurement technique in order to detect the low current of impressed current cathodic protection system (iccp). the current study was devoted to the modification of the ina219 bidirectional sensor by adapting it to the labview environment in order to develop an automated current measurement system for less than 25 ma. 2. experimental work this section discusses the instrumentation system that has been designed and implemented using the following hardware (practical system) and software systems (labview and matlab): 2.1 hardware figure (1) shows the hardware of the instrumentation system which includes the following parts: fig. 1. the components of the instrumentation system (created by fritzing software). 1. the microcontroller: the arduino development board serves as the control unit's primary component. six built-in analog input pins and fourteen digital input/output pins, six of which are used for pwm, are included [14]. 2. current/power sensor: the ina219 sensor, introduced by texas instruments, serves as the foundation of the current measurement circuit. the bidirectional sensor ina219 detects the bus voltage within a range from 0 to 26 v. the instrument requires a supply voltage of 3 to 5.5 v and consumes up to 1 ma of supply current. the sensor's operating temperature range is -40°c to 125°c. the voltage across a 0.1ω resistor can be measured by a precision amplifier. it can measure up to 3.2 a because the amplifier's highest input difference is 320 mv. the internal 12-bit adc precision at the 3.2 a range is 0.8ma. the maximum capability of current and resolution abdulrahman b. khudhair al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 8897 (2023) 90 detection is 400 ma and 0.1 ma respectively, with the internal gain set to the lowest of div8. the i2c protocol can be utilized to interface the adrfruit ina219 module sensor to an arduino uno [15]. this sensor can detect the voltage, current, and power on the load by measuring the bus voltage and the voltage drop on the terminals of a shunt resistor of 0.1ω to measure the current. the accuracy of measurements can be improved by programming registers .a bank of 16 bit registers ranging from 00 to 05 hexadecimal are used by the ina219 to store configuration parameters, measurement data, maximumminimum limits, and status details (table (1)). with the configuration of registers, the function and mode of operation are set. for example, figure (2) illustrates the features of each bit in the first register with address 00 hex, which indicates that it is a read-write configuration register and that it holds data. table 2 tabulates the selected data to support the requested goal and objectives of the current work. fig. 2. configration of 00 hex register. table 2, the content of configruation rgister ina219 sensor. bit config num. bit fill discription rst 15 0 power-off reset 14 0 brng 13 0 0 =16v fsr (full scale range) pg1 ,pg0 12, 11 00 range = ±40 mv badc 10,9,8,7 0001 mode ( 10 bit) sadc 6,5,4,3 0001 mode ( 10 bit) mode 2,1,0 111 shunt and bus, continuous the 16-bit configuration register is loaded with the binary (0000 0000 1000 1111) or 008f in hexadecimal. the values for shunt voltage, bus voltage, power, and current are stored in the registers with addresses 01 through 04 hex, which are read only. the last address 05 hex register is a calibration register that is set accordance to the data sheet's equations and the work requirements as [15]: current � � � 2�� … �1� where im is the maximum expected current which equals to 0.4 a. by substituting im in equation (1) and rounding to the nearest: current � � �.� ��,��� � 0.00001221 � 0.0001 the current lsb is multiplied by current register (04h) content to convert a value to the actual current in amperes. table 1, the registers of ina219. by substituting the value of the currentlsb and value of the shunt resistance of the adafruit ina219 sensor module in equation (2) with truncate the decimal values from the result . [15]: cal � trun ! 0.04096 current� % r '()* + … �2� where cal is the calibration, trun is the truncate, rshunt is the shunt resistance (ω). based on equation (2) , the calibration register is calculated. cal � trun ! 0.04096 0.0001 % 0.1+ � 4096 by substituting the value of the currentlsb in equation (3) [data sheet – ina219]: powerlsb = 20×currentlsb … �3� powerlsb = 20×0.0001 = 0.002 for a power value in watts, the power register (03h) content is multiplied by power lsb, which is 20 times the current lsb. 3. voltage driver: l298n dual h-bridge module used supply the system requird voltage (0v to 5v) and current up to 2a as maximum output current. the ena port is delivered a pwm signal out from arduino. the driver outputs 1 and 2 were utilized, and high and low voltages were delivered to in1 and in2, respectively, to generate positive pointer address register (legendr=read, w=write) hex 00 configuration (r/w) 01 shunt voltage (r) 02 bus voltage (r) 03 power (r) 04 current (r) 05 calibration (r/w) abdulrahman b. khudhair al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 8897 (2023) 91 and negative voltages, at out1 , out2 respectively. driver input was connected to a dc source with a 500 ma, 11.85 v output that ranged from 0 v at 0% duty cycle (dc) to 11 v at 100%. 4. low pass filter (lpf): a passive low pass filter is a resistor-capacitor (rc) circuit used to smooth the analog output of the l298n by cutting off the higher frequency and passing the low frequency. the values of the resistor and capacitor are 201.7 ω and 338.2 µf respectively. the transfer function for this lpf is given by[16]: -�.� ≡ 0123 045 � 1 1 6 78. … �3� 5. the applied load: to analogize the iccp system and observe the value of current flow in milli ampere and power consumption in milli watt, a resistor of 55 ω was utilized, which requires less voltage than the rc low pass filter resistance. 2.2 software matlab/simulink and the graphical pramming labview were utilized in driving and executing the setup harware: 1. matlab/simulink: used to illustrate the output voltage profile, cut-off frequency, and transfer function analysis utilizing bode diagram as shown in figure (3). fig. 3. block diagram in simulink. 2. labview sub vi design: labview was implemented to programming the embedded platform (arduino uno) through the linx firmware. it acquire data from the ina219 sensor and adjust the dc for the l298n voltage driver. figure (4a) illustrates the designed labview's front panel that is employed to control the dc's value from 0% to 100%. in addition monitoring the system during performance namely the voltage, current and power as well as other control operations. figure (4b) shows the connector pane after the sub vi creation, design, and setting of the terminals that correspond to the controls and indicators of the ina219 sensor. the help, or benefit, for the user, of the interface of the ina219 sensor with labview is presented in figure (4c). utilizing the i2c linx toolkit built into the labview block diagram, the ina219 current sensor is configured by identifying a slave address with a value of 40 hex. the rc low pass filter circuit causes ripple voltage. this problem was solved using a moving average filter in the labview code. more stable values were obtained by employing a median filter for every 10 samples. a while loop with a 10-millisecond waiting time is utilized. fig fig. 4. labview sub vi for the ina219 bidirectional sensor: (a) front panel, (b) connector pane and (c) sub vi help. as illustrated in figure (5), the flowchart presents the steps involved in adapting the ina219 sensor to work with labview software. the labview graphical code was developed to read the electrical data from the sensor and display it on the user interface. finally, the code was tested and refined to ensure accurate and reliable electrical measurements. abdulrahman b. khudhair al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 8897 (2023) 92 3. result and discussion the created sub vi for the adafruit ina219 sensor module was tested and analyzed through behavior data acquisition during the field tests of the system. the features were modified to meet the requirements of each test, necessitating redesigns. this modification accommodated the needs in regard to the connection between all the components of the instrumentation system. this system offers the benefits of being dependable, low-power, and efficient for very low-level dc electrical measurements. the current, voltage, and power measurements, as well as the performance of this instrumentation system, are presented and discussed in the next subsections. fig. 5. flowchart presents the steps involved in adapting the ina219 sensor with labview. abdulrahman b. khudhair al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 8897 (2023) 93 3.1 rc low pass filter as mentioned before, the role of the rc circuit is to smooth the applied pwm voltage for the load. a square voltage of 11 v was applied at a frequency of 980 hz and a dc of 50%. the applied voltage takes a settling time of 0.157 sec to reach the steady state of 4.95 v, as shown in the graph extracted from matlab/simulink in figure (6). referring again to figure (6), the steady-state voltage shows regular periodic ripples with a peak-to-valley difference of 41.1 mv, which were passed by the rc low pass filter. the bode diagram in figure (7) shows the cutoff frequency is 2.33 hz at magnitude -3 (db) and a phase angle of -45o at the same the cut-off frequency. fig. 6. the profile of applied voltage of 4.95 v at dc frequency of 980 hz to the load (extracted from simulink). fig. 7. the bode diagram reveals a cut-off frequency of 2.33 hz (-3db) and phase angle of -45 o . 3.2 electrical characteristics the experiments were achieved by pwm control for the power across the system with a duty cycle from 0% to 100% via the arduino and labview code in order to supply the load and rc filter with a range of voltage from 0 to 11 v. an increment of 5% in duty cycle results in a spectrum of voltage, current, and power data across the load, which is acquired by the ina219 sensor. to investigate the error and performance of the instrumentation system, the experiments were repeated after switching the ina219 sensor with a sensitive multimeter of type uni-t ut39a+. the experiments were conducted twice with the multimeter, the first time with the components connected in parallel to measure the voltage and the second time with the components linked in series to measure the current. the data obtained from the experiments for the voltage, current, and load across the load will be presented as follows: 1. voltage: figure (8) shows the measured voltage by the ina219 sensor (vs) and the multimeter (vm) for the range of duty cycle from 0% to 100%. the graph shows a great matching betweem the true and measured values of voltages. this match is expressed by the percentage of full scale error (er) which has inverse proportionality with the duty cycle. the ina219 sensor shows lowest error value of 1.5 % and highest value of 2.3% which considere a highly acceptable narrow band over the range of employed duty cycle. abdulrahman b. khudhair al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 8897 (2023) 94 fig. 8. vs of ina219 sensor versus vm of multimeterover the employed range of duty cycle. 2. current: the current detected by the ina219 sensor (is) and the multimeter (im) during the range of 0% to 100% duty cycle are shown in figure (9). the differences between the sensor and multimeter values exaggerate as the duty cycle increase where the error between reading extends. these graphs of is and im are correlated with acceptable error values up to 40% duty cycle which starts to expand after this value. at 5% duty cycle the error is 0.1% which became in itsan maximum value of 7% at 95% duty cycle. fig. 9. is of ina219 sensor versus im of multimeter over the employed range of duty fig. 3. power: the electrical power consumed by the load was obtained from the sensor output (ps) as well as that calculated theoretically (pc) by multiplying the vm with im for each value of the duty cycle is graphed in figure (10). the sensor shows a threshold value in reading up to the duty cycle of 10%. after the threshold the sensor detects the least amount of ps equals to 4 mw versus 3.4 mw for pm at a duty cycle of 15%. the full-scale error of power keeps its minimum values at a duty cycle of 60% before climbing to higher values. fig. 10. ps of ina219 sensor versus calculated pc over the employed range of duty cycle. 3.3 performance characteristics some of the static characteristics, such as resolution and linearity, of the system were investigated. from the above data that was obtained from the sensor, the minimum value of the current that can be detected, which is represented by the resolution, was calculated. the resolution of the ina219 sensor at 1% duty cycle was 1 ma, which shows high manufacturing, with the resolution value of the multimeter represented by 1.012 ma in the same measurement conditions and duty cycle. this indicates a percent absolute error of 1.18%. m. mariappan et al. stated in their work that the acs712 current sensor with the arduino uno shows a resolution of 26.4 ma [17]. the output of the instrumentation system shows significant linearity, as represented by the acceptable coincidence between the output curves of vs and is and the linear trendlines of each curve, as illustrated in figures (11). the coefficient of determination (r2) value of 0.9966 for both graphs determines the average difference between the predicted values by the fitted line (trendline) and the actual values for the sensor. the value of sensitivity was estimated for voltage to be equal to 0.0233 volts/% duty cycle and for abdulrahman b. khudhair al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 8897 (2023) 95 current to be 0.4436 ma/% duty cycle. these results revealed that the adaptation of the employed sensor with labview makes this coupling suitable for the measurement of weak current values in corrosion-inhibiting applications. the levels of the measured electrical characteristics come in good agreement with the observed corrosion current values in the protection of low-carbon steel in amel s. merzah et al, work [18]. fig. 11. the linearty of the instrumentation system output, vs and is, supported by the linear equations over the employed range of duty cycle. the precision of the system in this work was evaluated by the coefficient of variation. the reading of the voltage, current and power show significant average precision of 0.36 %, 0.28% and 0.17% respectively. 4. conclusions one of the obstacles to employing sensors with the labview-arduino interface is the absence of their sub-vis. this study was devoted to building and programming a sub-vi for the ina219 bidirectional sensor suitable for extremely low electrical measurements. the following are the concluding remarks for the current study: 1. the highest absolute error was calculated for the full scale voltage around 2.3% at a value of 2.22 v. 2. the absolute error of the current at 2.2%, which is less than 25 milli-amps. it increases gradually with the increasing in current until it equals 7% at the current of 43 ma. 3. the highest absolute error for the full scale of power was at 5.8%. 4. the linearity of voltage and current were investigated utilizing fitting line, and the value of the coefficient of determination r2 was estimated as both were 0.9966. 5. measurements were highly precise and the values of the coefficient of variation were 0.36 %, 0.28% and 0.17% for the voltage ,current and power respectively. references [1] r. b. northrop, introduction to instrumentation and measurements, 3rd ed., broken sound parkway nw: taylor & francis group, 2014. [2] j. m. shah, r. anand, s. saini, r. cyriac, d. agonafer, p. singh and m. kaler, "development of a technique to measure deliquescent relative humidity of particulate contaminants and determination of the operating relative humidity of a data center," in proceedings of the asme 2019 international technical conference and exhibition on packaging and integration of electronic and photonic microsystems, anaheim, ca, usa, 2019. [3] m. nizam, h. maghfiroh, a. ubaidilah, i. and f. adriyanto, "constant current-fuzzy logic algorithm for lithium-ion battery charging," international journal of power electronics and drive systems (ijpeds), vol. 13, no. 2, pp. 926-937, june 2022. [4] w. indrasari, r. fahdiran, e. budi, u. umiatin and n. s. yusuf, "development of static solar panel equipped by an active reflector based on ldr sensors," in 5th international seminar on mathematics, science, and computer science education, bandung, 2019. [5] đ. lazarević, m. živković, đ. kocić and j. , "the utilizing hall effect-based current sensor acs712 for true rms current measurement in power electronic systems," vol. 72, no. 1, pp. 27-32, 2022. [6] n. cameron, electronics projects with the esp8266 and esp32: building web pages,applications, and wifi enabled devices, edinburgh, uk: apress, 2021. abdulrahman b. khudhair al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 8897 (2023) 96 [7] k. ap, m. jk, i. ko, m. d and k. jg, "current and voltage data logging from microbial fuel cells using arduino based sensors," international journal of robotics and automation, vol. 7, no. 3, pp. 90-93, 5 november 2021. [8] m. nizam, h. maghfiroh, ,. f. n. kuncoro and f. adriyanto, "dual battery control system of lead acid and lithium ferro phosphate with switching technique," world electric vehicle journal, vol. 12, no. 4, 1 january 2021. [9] h. maghfiroh, j. t. affandy, f. adriyanto and m. nizam, "single phase inverter with power monitoring using arduino," in 2nd international conference on science & technology, yogyakarta, 2020. [10] a. a. musyafiq, n. a. ilahi, r. p. dewi and u. barokah, "simulation of piko hydro power generator using thread turbine with 10-watt power," journal of telecommunication network, vol. 12, no. 2, pp. 100-104, 2022. [11] s. h. cheragee, n. hassan, s. ahammed, a. z. md and t. islam, "a study of iot based real-time solar power remote monitoring system," international journal of ambient systems and applications, vol. 9, no. 1, pp. 27-36, june 2021. [12] e. wiyadi, a. wati, y. hamzah and y. , "simple i-v acquisition module with high side current sensing principle for real time photovoltaic measurement," in international seminar on sensors, instrumentation, measurement and metrology, padang, 2020. [13] a. t. nugraha, d. priyambodo and s. t. sanera, "design a battery charger with arduino uno-based for a wind energy power plant," journal of physical science and engineering, vol. 7, no. 1, pp. 23-38, 18 april 2022. [14] r. singh, a. gehlot, b. singh and s. choudhury, arduino-based embedded systems interfacing, simulation, and labview gui, broken sound parkway nw: taylor & francis group, 2018. [15] data sheet, ina219 zerø-drift, bidirectional current/power monitor with i2c interface, texas instruments incorporated, 2015. [16] w. h. hayt jr, j. e. kemmerly and s. m. durbin, engineering circuit analysis, 8 ed., new york: mcgraw-hill, 2012. [17] m. mariappan, h. f. shun and k. muthukaruppan, "electrical consumer panel with automated leakage current detector system," international journal of integrated engineering, vol. 12, no. 2, pp. 46-54, 2020. [18] a. s. merzah, m. h. hafiz and s. k. mohammed, "corrosion control of buried low carbon steel structure by using alteration medias method," al-khwarizmi engineering journal vol. 10, no. 2, pp. 65-74, 2014. ���� ���� � د19ا��� ��� ا� �� ���� ا���ارز�� �� ا��� )2023( 88-97، ! �� 3، ا� 97 , adafruit ina219�*+ ��labview ��(� ا������� )� ا� sub vi و ة إ$�#ء ا�1 �#ت ا����1#��0 ��� �� ا� +,�ى ��.#-� ,�+*� *���� ���� � ا���� **��+ )�ات ا��اھ�4 ي��� ا� أ���*** اد *،**�� ا���ارز��/ ����� ا������ /� ا�$���#"و �� اد/ ا��"اق)'& ھ��� / ا�$��� ��� وا�,.�� /�"�2 أ��0ث ا�,.��ا�$,+ م***� ا������/ 3��4 د� � ����/ 3� إ4"�� ا /د� abd.basheer2102m@kecbu.uobaghdad.edu.iq*ا�8"4 ا�7�,"و �: furatnejjar@uobaghdad.edu.iq**ا�8"4 ا�7�,"و �: muhannad.ahmedobeidi@dcu.ie **ا�8"4 ا�7�,"و �: ا��8!� �< =�م ا�4�$0 ا���>�د4 ���,��ر ا�+'"ي (?,4iccpس��( ( &�( 4���� bc���� d$ا ا��eھ �f . �h��"��ا� i.h�.� &# � �عم ا�$اأٌ�,�'0, adafruit ina219 س���+ �lا�,��ر وا�و )�& ا� �h��"��رة ا� + �nا",fا d$0� ر��e$ا��=�م ا� d$o ���04iccp و 4���� bc��� .ا�eي 4',��q ط�) �'�h"ا� ��r$3 ا�$�# �fا�+��س ��$s ھ��f ا�"اءات v���#ا�$�'0, ina219 �f icظ��# �s x�� ا�"����l�"8ا�labview م s >8'� 8,�� "f�#i� �c4"�# او اي اداة yا��� i,. �f d$ا ا��eھ &# v���# ���$adafruit ina219 dا�$,0'� x�� �f labview ء�r ة �3 \]ل إ oو �l�"� sub vi ح � �وا\,�8رھ �و#?�4"ھ�l��, ً2ن ��ھ��ة d$�� و�$hم ��ا�= iccp `�� "� -�labview. a$# ��$s ج"\ ا�$,0'� �"ا)8 دوات ا�8"ا7و arduino uno$,0�& ا����,� ام �l� labview-linx. c8ض ا��"s d4 �# ��+# e�8?# &# pwm 3� 0وا�,� #,"اوح fإ� ٪ ��=&�,2و4 $,0�& ا� �3 \]ل٪ 100�lا�l298n ض"�� �lا�$ #�=�& ا�h�' f�s ا.d$0� م#& ا�,�<[< [f"# وھ� ",�f ع� moving average filter �� h��,� ا�,$�ج �+��س ripple و",�cا� median filter اء"( f�s 0.�ل��," داh"ة4 وا�,+"ار��>�)� و ا�i" ات�cا� passive low-pass filter &���,� &�( �lا�pwm d8(i?��'# s.d$0ا� f� vظ��# &# x�� ا�$�#]ب matlab-simulink ا�#"دد �+��س-?+ �acr و�� k�o ا�,$�ج ره ا��,�3s `h )�& #"دد )?-(2.33 hz و ره �3 ا�+$ ا�f ا�+$ #$�ج ��( 41.1 mv ره �$',�r" ا�$��4"ة أظ�"ت ,�s. `h 0.157وز�3 ا�,+"ار ) ina219 $�( e��ا��?m ا�$?� �l �h��"��ظ�" ٪.2.3��0ا�� ا� ، qذ� fإ� f�np��ا� ت &�( m?ا�� ��f e ا�,��ر ��'8?$2.2 �s ٪25 ma ��42دة و �l4ر # 4 s�.# f7إ� �s ٪43 ma �� �$���a f�sأ $�(�� e�?� m?\رة ���� "اءاتا�+ ٪.5.8 ھ� +s ا�,� #& ا�0.�ل �a د)l� و ���s dl� وا�,��ر وا�0.17٪ و 0.28٪ و 0.36 )�& ) رھ� ����d اr\,]ف�l�� ٪ �h��"��رة ا� �f ا�,�ا��. +s this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 20, no. 2, june, (2024), p p. 1425 finite element analysis of new designed intercalary prosthesis implant (ulna bone) sadeer anwer mustafa*, ahmed z. m. shammari**, wmieth a. j. augla*** and m. n. mohammed**** *,** department of automated manufacturing engineering , al-khwarizmi college of engineering , university of baghdad, baghdad, iraq *** yarmouk teaching hospital , ministry of health , baghdad ,iraq **** department mechanical engineering , college of engineering/ gulf university, sanad 26489, bahrain *email: sadeer.anwer1991@gmail.com corresponding author: **email: drahmed@kecbu.uobaghdad.edu.iq ***email: wajoaz77@gmail.com ****email: dr.mohammed.alshekhly@gulfuniversity.edu.bh (received 3 september 2023; accepted 28 january 2024; published 1 june 2024) https://doi.org/10.22153/kej.2024.01.001 abstract implantation via an intercalary prosthetic method is a reliable solution for reconstructing a long defect in bones that has been damaged by severe disease or accidents. in the current study, using data from computed tomography (ct) scans, a novel costumed intercalary prosthesis design has been created. to achieve this purpose, the ct scan data of a patient in (dicom) file format was converted into computer-aided design models and saved in stereolithography (stl) format using the 3d slicer (5.0.3) software. the stl files were loaded into meshmixer software to design the models of the intercalary prosthesis. finite element analysis (fea) was applied to validate the strength of the prosthesis with impact, tensile testing, and torsional testing. according to the results of the impact tests, the highest recorded deformation was 8.8485e-002 m in the area where the implant body interfaces with the bone intramedullary canal, due to the high-stress (von mises stress) value of 3.78 e9 pa. in the torsional loaded the highest deformation recorded was 1.3871e-008 m when the von mises stress reached 49006 pa, and with the application of the tensile test the largest deformation measured as 1.0458e-006 m at maximum von mises stress seen was recorded as 6.6012e+006 pa which caused that. a solid rod of ti6al4v alloy was selected. finally, the analysis proved that the implant had enhanced mechanical properties. based on the findings, it can be inferred that the prosthesis was successfully implanted, and a satisfactory result was obtained by using this design method. keywords: intercalary prosthetic; computed tomography (ct); dicom file; stereolithography (stl); finite element analysis (fea). 1. introduction in fractures of the adult diaphyseal forearm, exact anatomical repair is necessary to achieve bone union and good functional results. consequently, surgical intervention is required for the majority of adult diaphyseal forearm fractures. [1]. forearm fractures can be successfully treated with open reduction and plating osteosynthesis, a method that has been used for a long time and has shown great results in terms of functional outcomes. [2]. intercalary prosthesis implantation and other forms of elastic-stable intramedullary fixation have made it feasible to stabilize unstable fractures with less invasive procedures, which in turn has reduced discomfort, improved limb function, and improved patients' quality of life when dealing with humeral diaphyseal bone metastases. [3-4]. when treated with open reduction and plating, comminuted or segmental mailto:sadeer.anwer1991@gmail.com mailto:drahmed@kecbu.uobaghdad.edu.iq mailto:wajoaz77@gmail.com https://doi.org/10.22153/kej.2024.01.00 sadeer anwer mustafa al-khwarizmi engineering journal, vol. 20, no.2, p.p. 1425(2024) 15 forearm fractures have an increased risk of infection and non-union. because intramedullary fixation has numerous advantages over plate fixation—such as fewer periosteal stripping, retention of the fracture hematoma, and the biomechanical benefits of a central load-bearing implant—it is used for adult forearm fractures. [57]. in the same concept, the missing bones that resulted from the removal of tumors are treated by using a custom design of the intercalary prosthesis [8]. this technique assists in preserving the remaining osseous part and functional reconstruction after tumor resection using a personal osteotomy guide plate and prosthesis based on 3d printing technology [9]. intercalary prostheses are a growing possibility for diaphysis segmental defect reconstruction due to the development of cementation and ingrowth fixation procedures [10]. the most popular treatment for treating imminent and pathologic bone fractures is intramedullary nail fixation. however, this procedure is known to cause long-term discomfort, weakness, and limited mobility [11]. biomechanical principles state that periosteal bone heals with callus when a load-sharing implant, like an intramedullary nail, causes a specific amount of strain. while this theory works for various types of long-bone fractures, it is most useful when dealing with comminuted fractures [12]. a finite element model was developed to simulate traffic collision scenarios involving adult bone fractures. the primary objective of this model was to evaluate the extent of injuries received in different parts of the skeleton [13-14]. in order to learn more about the bones' mechanical strength and how loads are distributed, many researchers have used finite element (fe) analysis on human forearm fractures [15]. by analyzing x-ray images for geometric and material properties, patient-specific finite element models can be constructed. due to its efficiency in collecting data on both static and dynamic reactions, finite element analysis (fe) has found widespread application in implant biomechanics research. [16]. this work aims to study a new customized intercalary prosthesis implant for forearm bone and segmental defect reconstruction. in order to develop the current intercalary prosthesis, the data has been carefully derived from the patient's computed tomography (ct). consequently, the finite element method (fem) has been established to numerically evaluate the model's dependability for intercalary prosthetics. 2. design and selection of implant for patient forearm the individual, a female aged 50, sustained closed fractures of the ulna and radius subsequent to a motor vehicle collision in january 2021. upon injury, the patient was immediately admitted to a local hospital, and surgeries were performed to fix the fractures. the present case currently requires a new surgery with the design and manufacture of a new intercalary prosthesis implant due to the fractures being classified as complicated as a result of the extensive fragmentation observed in the damaged bones as shown in fig 1. fig. 1. ct for the ulna and radius. therefore, a titanium alloy medical implant was purposefully developed to replace the affected portions of both the ulna and radius bones, employing a uniform design for both skeletal structures. sadeer anwer mustafa al-khwarizmi engineering journal, vol. 20, no.2, p.p. 1425(2024) 16 the present study provides a comprehensive understanding of the design process involved in the development of a medical implant specifically designed for the ulna bone. the severity of the forearm damage was determined by a ct scan. in order to create a 3d digital model of the implant, ct scan data was collected and transmitted to e3d 64v in dicom format. the stage of analysis of the design of the pulverized part began as soon as the ct format was converted to the stl extension using a 3d slicer (5.0.3). this was done in an attempt to find the best design for a particular circumstance. the stl file was initially imported into mashmixer software (3.5.474). taking advantage of human symmetry, we were able to accurately measure the broken part of the healthy bone on the opposite side and create a medical implant with identical proportions. using the mirror and the symmetry command, we were able to flip the healthy component of the mirror image and subtract the broken piece from the whole as shown in fig 2. fig. 2. symmetry of forearm bone. upon calculating the suitable sizes for the implants, the solidworks software version 2021.2 has been utilized. the application was employed for the purpose of design, specifically for the initiation of the ulna bone segment design, as outlined in the subsequent description. to get the best connection to the bone and figure out the right piece's direction, an octagonal shape element is first constructed to be the most appropriate for facilitating osseointegration with a 14-mm diameter is first constructed. then, a 12mm-diameter cylinder was made on the octagonal face to act as the implant body's support, and the sector with the best mechanical properties was identified as the implant sector (fillet). the implementation of fillets serves to disperse stress across a wider surface area, hence enhancing the durability and load-bearing capacity of the components, as shown in fig 3. fig. 3. octagonal element and cylinder shaft. shapes an octagonal one will provide optimal contact with the surrounding bone while still allowing for bone growth and blood to flow to the area for osseointegration. an incision on the front of the implant reveals the connection to another implant, as shown in fig 4. fig. 4. bone intramedullary canal shaft and the location of contact with the complementary implant structure. fig. 5. osseointegration between the bone and the proposed implant [17]. sadeer anwer mustafa al-khwarizmi engineering journal, vol. 20, no.2, p.p. 1425(2024) 17 then, an implant with an upward projection was designed to facilitate its integration with the other component, thereby ensuring stability and preventing displacement. likewise, the height of the negative projection on the opposite side was determined using the same measurements for the protrusion and emergence. upon completion of the protrusion, attention was redirected to the screwinsertion holes, which serve to secure the two implant components together. pre-drilling and tapering were performed on the implant to facilitate the insertion of m 3.6 screws, as shown in fig 6. fig 6. cylinder shaft implant and its holes screw. three holes with a difference of 90 degrees were placed at the bottom of the implant to share it with the bone and for the bone itself to be built on it for a complete interlock after the bone has completely healed. three holes were placed in two different surfaces of the trunk for complete connection later between the bone and the implant, 45-degree angle stem feathering aids implant entry during the surgical process, as shown in fig 7. fig. 7. fixing screws of bone marrow shaft. the initial component of the implant was successfully constructed, while the subsequent component exhibited symmetry and required few alterations to its connections. the implant was manufactured using the solidworks software package. the measurements used in this work are illustrated in fig 8. fig. 8. assembly of the implant. 3. intercalary prosthesis implant material the material used in this study is titanium alloy (ti6al4v), table 1 shows the material’s chemical composition. ti alloy is a biomaterial of exceptional quality that finds extensive application in the biomedical field, specifically in the fabrication of orthopedic implants, cranial implants, dental implants, ti mesh, and artificial joints all contain ti alloys [18]. ti alloys generally sadeer anwer mustafa al-khwarizmi engineering journal, vol. 20, no.2, p.p. 1425(2024) 18 comprise the principal constituent ti, as well as possible additional elements including vanadium, niobium, aluminum, and zirconium. by utilizing ti as its primary constituent, the material attains exceptional biocompatibility and lightweight characteristics, there by mitigating the potential for rejection reactions. the incorporation of elements such as aluminum and vanadium into a material can augment its strength and resistance to corrosion, thus enhancing its stability during implantation. niobium incorporation has the potential to enhance biocompatibility and mitigate tissue reactions [19]. for numerous years, metal implants have been employed in the medical field to secure prosthetics or substitute absent organs or tissue [20]. ti-6al4v implants have the potential to become the most effective method for regenerating significant bone defects, according to many results [21]. at the present time, total hip replacement stands as one of the most frequently conducted surgical procedures [22]. an approximated 15–20 years is the average lifespan of hip replacements or 75% by way of estimation. [23]. ti alloys are extensively employed in the fabrication of implants owing to their favorable mechanical properties and biocompatibility [24]. table 1, chemical composition of titanium alloy (ti6al4v). element al v fe mo si cu w nb ni sn mn ti composition (%wt.) 6.37 4.33 0.03 0.01 0.01 0.01 <0.01 0.008 <0.005 <0.005 <0.004 balanced 4. finite element analysis for implant the research methodology employed for the implementation of split prostheses for ulna replacement focused on conducting a comprehensive analysis with the assistance of appropriate design software. all samples were loaded with different types of load impact, torsion, and tension on various fixation areas. in each case, to find out the weaknesses of the implant model and the maximum stresses that lead to the failure of the model. first, a three-dimensional model of the implant was created for the fe analysis of the intercalary prosthesis implant. the model employed was rebuilt using data from ct (dicom) images and represented a replacement for the ulna shaft from the forearm bone. it was afterward imported into (ansys 2020/r1), fig 9 summarizes the methodology of finite element analysis as a flowchart, and the medical model underwent three tests include: fig. 9. methodology of finite element analysis. sadeer anwer mustafa al-khwarizmi engineering journal, vol. 20, no.2, p.p. 1425(2024) 19 4.1 impact test high-load-rate medical implant fracture characteristics can be determined using impact testing, an analysis method developed for this purpose. the finite element method (fem) simulated the implant's dynamic effect. the implant passed its impact test, which involved an impact with a 0.96 kg item at 100 m/s on the x-axis. the stress distribution and von mises stress have been recognized as vital elements in finite element analysis. meshing is an important step for finite element analysis of the implant model. smaller elements were used on the model's proximities and curvatures with the help of a model wizard in (ansys 2020/r1) to create an optimal mesh. the number of triangle surface mesh components used in the implant model is 13146, and the number of nodes is 3664, as can be seen in fig 10. fig 10. mesh generation of impact test. 4.2 torsional test torsion is a widely employed testing technique utilized for the evaluation of the torsional yield strength and deformation of customized implant bone specimens under standardized conditions. the concept of elements and nodes refers to a fundamental constituent or component of a system, that has the number of triangle surface mesh elements used for the implant model as 2433, while the number of nodes is 5238, as shown in fig 11. fig. 11. mesh generation of the torsional test. 4.3 tensile test fea was conducted in order to get insight into the distribution of stress under a tensile load. the stress distribution resulting from the preload application of a 50 newton in the y-axis is determined using the model developed by the fem, as shown in fig 12, the triangle surface mesh elements utilized for the implant model amount to 2433, while the number of nodes totals 5238. fig 12. shows the axial load and fixed support. 5. result and discussion three groups were set up for finite element analysis testing: impact test, torsional tests, and tensile tests. von mises stress and deformation were observed as the main factors in fea. to observe the von mises stress nephogram and deformation, data were collected from the ansys general postproc. the unit of stress was pa, and the values presented in this study were under an impact load of 0.96kg at 100m/s, torsional load 1.e-003 n.m, and tensile load 50 n. to check the implantation of an intercalated prosthesis, the boundary conditions were applied to the finite element analysis; one end of the implant was fixed in the fixture and the other lateral limb was loaded with hypothetical values of impact load, tensile strength, and torque. in this aspect, the results showed that the ulnar finite element model is able to accurately predict its biomechanical properties, the von mises stress of impact load valued was 3.78 e9 pa, as fig 13, and the highest recorded deformation was 8.8485e-002 m, as fig 14, caused by an impact of the body moving at high speed in a direction perpendicular to the intercalary prosthesis implant. to find out the weaknesses of the implant model and the critical stress that lead to its failure. sadeer anwer mustafa al-khwarizmi engineering journal, vol. 20, no.2, p.p. 1425(2024) 20 fig. 13. von mises stress during an impact test. fig. 14. total deformation and its diagram for impact test. and during the application of a torsional load, the location where the implant body made contact with the bone intramedullary canal coincided with the position at which the von mises stress reached 49006 pa, fig (15). this analysis also revealed that the highest deformation recorded was 1.3871e-008 m, fig (16). fig 15. von-mises stress during a torsional test. sadeer anwer mustafa al-khwarizmi engineering journal, vol. 20, no.2, p.p. 1425(2024) 21 fig 16. total deformation and its diagram for a torsional test. in the tensile test, the maximum stress seen was recorded as 6.6012e+006 pa, fig (17), while the corresponding largest deformation was measured at 1.0458e-006 m, fig (18). all the numerical results of the tests were summarized in table 2. fig. 17. von-mises stress during a tensile test. sadeer anwer mustafa al-khwarizmi engineering journal, vol. 20, no.2, p.p. 1425(2024) 22 fig. 18. total deformation and its diagram for a tensile test. table 2, summary of numerical result of test type of test max. stress (pa) deformation (m) 1. impact test 3.78e9 8.8485e-2 2. torsional test 49006 1.3871e-8 3. tensile test 6.6012e6 1.0458e-6 the treatment outcomes in the upper limb are still being impacted by mechanical difficulties, including aseptic loosening and structural failure [25,26]. six patients were studied by ahlmann and menendez; three had tibial prostheses, two had femoral prostheses, and one had a humeral prosthesis. only the humeral prosthesis required revision at 14 months due to aseptic loosening; increased rotational loads in the upper extremity were thought to contribute to a higher rate of failure. higher rotational forces in addition to a shorter length of segment attachment and a smaller diameter for cement interdigitation compared to the femur were blamed for the eventual structural failure [27,28]. the utilization of finite element analysis in the field of biomedicine has demonstrated its efficacy through its interverification and inter-complementarity with classical biomechanics [29,30]. finite element analysis is superior to previous experimental approaches because it causes no harm to specimens while accurately simulating the stress distribution in living tissue. on the other hand, finite element models are reusable, and their analysis is rapid and economical. 6. conclusion recent research supports the use of prostheses as part of a comprehensive treatment plan to restore bone function following injury. as a more effective biological treatment option, split prostheses are more popular. therefore, this study presents an innovative ulnar defect reconstruction method using an intercalary diaphyseal prosthesis. the ulna is modeled using finite elements. the results of the finite element analysis reinforce the hypothesized assumption that the innovative prosthesis can provide stronger initial stability under impact, torsional, and tension forces which are typically applied by forearm movements, where the max equivalent von mises stresses are 3.78 e9 pa,49006 pa, and 6.6012e+006 pa respectively. and so a new method has been developed for treating forearm fractures. compared to biological treatments, the implants have superior mechanical properties that allow them to withstand extremely high stresses until failure, making them an excellent choice for use in bone replacement surgeries. references [1] schulte lm, meals cg, neviaser rj. management of adult diaphyseal both bone forearm fractures. j am acad orthop surg. 2014;22:437–46. 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(2018). al-khwarizmi engineering journal, 14(4), 1-8. https://doi.org/10.22153/kej.2018.03.005. https://doi.org/10.22153/kej.2018.03.005 (2024) 14-25، صفحة 2، العدد20مجلة الخوارزمي الهندسية المجلد سدير انور مصطفى 25 تحليل العناصر المحدودة للزرع االصطناعي المقسم المصمم حديثا )عظم الزند( ****محمد الشيخلي، وميض علي الزبيدي*** ،أحمد زيدان الشمري** ،سدير أنور مصطفى* العراق ،بغداد ،جامعة بغداد ،كلية الهندسة الخوارزمي ،قسم هندسة التصنيع المؤتمت *،** العراق ،بغداد ،وزارة الصحة ،مستشفى اليرموك التعليمي *** ينالبحر ،26489سند ،جامعة الخليج ،كلية الهندسة ،قسم الهندسة الميكانيكية**** sadeer.anwar2204@kecbu.uobaghdad.edu.iq:البريد اإللكتروني * drahmed@kecbu.uobaghdad.edu.iq :البريد اإللكتروني ** wajoaz77@gmail.com :البريد اإللكتروني*** dr.mohammed.alshekhly@gulfuniversity.edu.bh:البريد االلكتروني**** الخالصة حوادث. في يعد الزرع على طريقة األطراف االصطناعية الداخلية حال موثوقا إلعادة بناء عيوب العظام الطويلة التي تضررت بسبب المرض الشديد أو ال ( . ولتحقيق هذا الغرض ، تم تحويل بيانات ct-scanهذه الدراسة الحالية ، يتم تطوير تصميم اصطناعي مقسم جديد من بيانات التصوير المقطعي المحوسب) ( باستخدام برنامج stl( الى نماذج التصميم بمساعدة الكمبيوتر وحفظها في شكل ستيريوليثوغرافي )dicomللمريض بتنسيق ملف ) ctاألشعة المقطعية (5.0.3)d slicer3 تم تحميل ملفاتstl في برنامجmeshmixer لتصميم نماذج من األ( طراف االصطناعية. تم تطبيق تحليل العناصر المحدودةfea ) -eتشوه مسجل للتحقق من صحة قوة الطرف االصطناعي مع اختبار الصدمة ، واختبار الشد ، واختبار االلتواء. ووفقا لنتائج اختبارات الصدمة كان أعلى باسكال. e9 3.78اخل النخاع العظمي ، بسبب الضغط العالي )إجهاد فون ميزس( بقيمة م في المنطقة التي يتداخل فيها جسم الزرع مع القناة د 8.8485 002 باسكال ومع تطبيق اختبار الشد ، تم قياس 49006م عندما وصل إجهاد فون ميزس إلى e-008 1.3871وفي ،اختبار االلتواء كان أعلى تشوه مسجل هو باسكال مع تسبب ذلك. تم اختيار عمود صلب من e006 6.6012إجهاد فون ميزس تم تسجيله على أنه م عند أقصى e-0061.0458أكبر تشوه على أنه وأخيرا ، أثبتت التحليالت أن الغرسة قد عززت الخواص الميكانيكية. وبناء على هذه النتائج ، يمكن االستنتاج أن الزرعة للطرف ti6al4vسبيكة على نتيجة مرضية باستخدام طريقة التصميم هذه. االصطناعي القت نجاحا ، وتم الحصول mailto:sadeer.anwar2204@kecbu.uobaghdad.edu.iq mailto:drahmed@kecbu.uobaghdad.edu.iq mailto:wajoaz77@gmail.com this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 20, no. 4, december (2024), pp. 70-88 defect detection using thermography camera techniques: a review hussein n. al-jubori1*, izzat al-darraji2 and houssem jerbi3 1,2 department of automated manufacturing, al-khwarizmi college of engineering, university of baghdad, iraq 3department of industrial engineering, college of engineering, university of ha'il, hail 81481, saudi arabia *corresponding author, s email: hussein.najeh2204@kecbu.uobaghdad.edu.iq (received 13 july 2023; revised 24 february 2024; accepted 11 august 2024; published 1 december 2024) https://doi.org/10.22153/kej.2024.03.002 abstract individuals across different industries, including but not limited to agriculture, drones, pharmaceuticals and manufacturing, are increasingly using thermal cameras to achieve various safety and security goals. this widespread adoption is made possible by advancements in thermal imaging sensor technology. the current literature provides an indepth exploration of thermography camera applications for detecting faults in sectors such as fire protection, manufacturing, aerospace, automotive, non-destructive testing and structural material industries. the current discussion builds on previous studies, emphasising the effectiveness of thermography cameras in distinguishing undetectable defects by the human eye. various methods for defect detection, including temperature analysis and image processing algorithms, are thoroughly presented. the factors contributing to the effectiveness of thermography cameras are explored, along with their advantages over traditional inspection methods. the literature review highlights the diverse applications of thermography cameras in fault detection. the review highlights the remarkable transformation brought by thermal camera technology in mechanical system fault detection, leading to improved maintenance practices. these cameras can detect unseen irregularities, enable non-invasive testing and support hands-on system maintenance, making them indispensable tools for ensuring mechanical systems operate efficiently, reliably and safely. with the continuous advancement of technology, the integration of industry 4.0 and iot technologies will further enhance the capabilities of thermal cameras, ensuring elevated performance across different domains. in electrical systems, thermal cameras allow for the early identification of faults, enabling proactive maintenance to mitigate risks. additionally, by assessing structural integrity, thermal cameras can detect thermal and insulation inefficiencies, leading to improved energy efficiency. keywords: thermography camera; defect detection; temperature analysis; image processing 1. introduction a thermal image camera (tic) is a type of imaging device designed to detect and capture infrared radiation emitted by objects, subsequently converting this thermal energy into a visible image. tics operate by measuring the thermal energy emitted from objects within their field of view. the amount of infrared radiation emitted increases proportionally with the temperature of an object, resulting in a corresponding increase in the brightness of the object as observed in the thermal image. this technology has a wide range of applications across diverse industries, such as manufacturing and building inspection. however, the literature reveals that many researchers have approached this subject from various perspectives. one crucial aspect of remote structural monitoring is the application of machine learning (ml) for detecting fatigue damage in glass–epoxy composites through thermal imaging. this technique plays a key role in remote structural monitoring, providing a reliable method for the safety evaluation and optimisation of composite structures and components [1]. however, the precise characterisation of fatigue-induced damage mailto:hussein.najeh2204@kecbu.uobaghdad.edu.iq https://doi.org/10.22153/kej.2024.03.002 hussein n. al-jubori al-khwarizmi engineering journal, vol. 20, no.4, p.p. 7088 (2024) 71 hotspots, encompassing their dimensions, morphology, spatial distribution, hysteresis-induced thermal effects and subsurface temperature profiles, through the application of surface thermal imaging techniques, continues to pose remarkable challenges in current research. the objective was to assess the theoretical accuracy of hotspot characterisation using an ml model trained on artificially generated thermal images derived from 3d finite element models with increasing levels of complexity. incorporating fatigue damage as an inherent heat source has been shown to effectively mitigate the impact of thermal image noise and other uncertainties related to heat transfer. the study demonstrates that ml can effectively and precisely retrieve the heat influx, depths and geometry of the heat source from the initial thermal images of composite materials. the prediction accuracies achieved ranged from 85% to 99%. the study also analysed the impact of variations in the size of the training set and image resolution on the level of prediction error. the results presented make a substantial contribution towards the development of precise and effective techniques for detecting fatigue damage in fibre composite materials remotely. in [2], two deep learning methodologies were examined for the purpose of restoring initial temperature profiles from thermographic images in the context of non-destructive material testing is examined. initially, a deep neural network (dnn) was trained in an end-to-end manner, where the surface temperature measurements were directly inputted into the dnn. subsequently, the surface temperature measurements were transformed into virtual waves, a novel concept in thermography, which were subsequently utilised as input for the dnn. a data generation system is devised and a dataset comprising 100,000 synthetic images depicting temperature measurements are produced to demonstrate the efficacy of the aforementioned techniques. various model-based reconstruction techniques, such as abel transformation, curvelet denoising and synthetic aperture focusing methods, were examined in time and frequency domains to establish an appropriate baseline. these methods are considered to be state-of-the-art in the field. furthermore, a tangible model was generated to facilitate assessment of entirely novel real-life data. according to the findings of multiple experiments, the end-to-end as well and hybrid approaches exhibited superior performance compared to the baseline in terms of reconstruction accuracy. the end-to-end methodology, in particular, exhibited superior computational efficiency and demanded minimal domain expertise. the utilisation of the hybrid approach necessitated a substantial amount of expertise in the relevant field and incurred higher computational costs compared to the end-to-end approach. the use of virtual waves has been proven to be a crucial aspect in simplifying the intricate process of end-to-end reconstruction. consequently, superior reconstructions were achieved with the same number of training samples compared to the traditional end-to-end methodology. furthermore, this approach facilitated the implementation of more condensed network structures and the integration of preexisting knowledge, such as sparsity and nonnegativity. the technique presented is particularly suited for non-invasive, two-dimensional examinations, specifically in scenarios where the amplitudes along objects remain constant, as in the case of metallic wires. in [3], a deep thermal imaging model was explored to investigation its application in close-range automated recognition, aimed at enhancing the understanding of people and universal technologies within their surroundings. the study employed a low-cost mobile thermal camera to collect thermal textures, which were then classified into distinct material types using a deep neural network. this approach proved highly effective in the absence of ambient light sources or direct material contact. additionally, the use of a deep learning network eliminated the need for manually designing a feature set for various materials. the performance of the system was assessed based on its capability to identify 32 distinct material types across indoor and outdoor settings. the methodology employed yielded recognition accuracies exceeding 98% in a sample of 14,860 images depicting 15 indoor materials and exceeding 89% in a sample of 26,584 images depicting 17 outdoor materials. however, the discussion of the potential real-time applications of this technology in human–computer interaction applications and its prospective avenues for further development is also observed. in [4], the researchers introduced a neural network based on deep learning and region convolution for detecting obscured objects. the identification of buried objects in thermal images involves using a region of interest selection technique with a bounding box. the experimental findings indicate that thermal images of buried objects exhibit temperature fluctuations due to changes in the heat-carrying capacity of the surrounding soil. the neural network approach proposed in this study demonstrated a 90% accuracy rate in predicting the locations of buried objects in thermal images. this method has the potential to be applied to land mine detection through thermal image processing techniques. the conditions of machines and other systems can be realised by hussein n. al-jubori al-khwarizmi engineering journal, vol. 20, no.4, p.p. 7088 (2024) 72 creating and classifying features that summarise the measured signal attributes. at present, professionals within their specialised domains formulate these characteristics using their expertise. thus, the efficacy and utility of the system are contingent upon the expertise of practitioners in the relevant fields of physics or statistics. additionally, if new and supplementary circumstances arise, specialists must incorporate innovative feature extraction techniques. in the study presented in [5], the authors explored a technique from the sub-discipline of feature learning, namely deep learning, using convolutional neural networks (cnns), to address the limitations of traditional feature engineering. the goal was to assess the feasibility and methodology of using deep learning techniques to automatically evaluate the operational state of machinery through the analysis of infrared thermal video data. this goal demonstrated the effectiveness of the proposed system in detecting various conditions in rotating machinery with high accuracy (95% and 91.67% for machine fault detection and oil level prediction, respectively) using infrared thermal data. notably, the system does not require extensive knowledge of the underlying physics, which may simplify the condition monitoring process using intricate sensor data. additionally, the use of trained neural networks enables the identification of important areas within infrared thermal images that are associated with particular conditions, potentially yielding novel physical insights. in [6], researchers introduced a thermal imaging process for assessing the electrical equipment status. they explored a broader range of anomalies compared to other thermographic surveys. numerous fault conditions have been determined to cause considerable heat dissipation, whilst some fault conditions have been found to result in even lower levels of heat dissipation compared to that of normal equipment. these conditions indicate a complex segmentation challenge. a pre-processing procedure, where the data is segregated into two discrete categories based on the thermal condition of the equipment, specifically denoted as the ‘cold’ and ‘hot’ states, is implemented to address this issue. subsequently, the segmentation process is conducted through the implementation of random forest and adaboost classifiers, employing a sliding window technique, whilst considering interpretable ml principles. furthermore, a novel collection of infrared images, featuring transformers and three-phase induction motors, has been generated. the method under consideration was evaluated using an identical dataset, resulting in outcomes that are currently unparalleled. the implementation of deep learning for automatic damage detection necessitates a comprehensive data repository that encompasses intricate pavement conditions. the presented study introduced a novel model for detecting surface damage by fusing thermal and rgb images. in [7], researchers investigated how detection outcomes are impacted by input data and network configurations across thermal, msx, fused image and rgb systems. the findings indicate that the accuracy of damage detection in the fused image can reach up to 98.34%. additionally, the use of an augmented dataset improved the stability of the detection model, resulting in a precision of 98.35%, recall of 98.34% and f1-score of 98.34%. in [8, 9], researchers introduced a deep learning model that integrates tic for detecting humans trapped in emergency situations, such as smoky fires, where visibility is notably reduced. the instantaneous results can be communicated to command centres as valuable data, enabling prompt rescue operations and ensuring the safety of firefighters before engaging in hazardous, smoke-filled fire scenarios. the application of deep learning methodologies, supported by comprehensive datasets that incorporate intricate pavement characteristics, has been proven effective in quickly identifying pavement deterioration. additionally, the use of low-cost infrared imaging technology, coupled with deep learning methodologies, has been shown to be an effective means for detecting pavement damage, particularly in cases where temperature variations are present. previous studies using pavement data collected under sunny conditions and analysed through the sa-resnet deep learning methodology achieved a predictive accuracy of 96.47%. in [10, 11], researchers focused on applying deep learning frameworks to datasets containing photographs taken during winter and summer sunny conditions to compare the predictive sensitivity, recall and precision scores. the findings of these studies indicate that moderate-resolution ir-t imaging cameras perform more reliably in summer than in winter conditions, as they yield higher predictive accuracy during warmer months. the studies also recommended the use of these cameras in such conditions due to their cost-effectiveness. researchers in objective studies [12, 13] explored automatic variations in cognitive evaluation tasks between a healthy control (hc) and a mild alzheimer’s disease (ad) group to detect the condition in real time. group differences were also examined using an artificial intelligence (ai) model based on thermal infrared imaging (iri) technology. using iri technology, the researchers conducted non-invasive observations of autonomic activity and its associated thermoregulatory manifestations hussein n. al-jubori al-khwarizmi engineering journal, vol. 20, no.4, p.p. 7088 (2024) 73 without affecting the psychophysiological state of the participants, thereby facilitating free communication with physicians. in this regard, overdependence on human experts is likely to be diminished. 2. applications thermal cameras have proven to be effective tools for detecting defects across various industries. their capability to gather and visualise the thermal energy generated by objects allow them to identify defects that may not be visible to the human eye. an overview of the application of thermal cameras in defect detection, as presented in figure 1, is introduced in detail in the following subsections. fig. 1. defect detection-based thermal camera applications 2.1 mechanical systems thermal imaging technology plays a crucial role in identifying anomalies in mechanical systems and equipment. detecting temperature variations can help identify issues such as bearing faults [14], misalignments [15], worn-out parts [16] and inadequate lubrication [17]. timely detection of these defects can notably enhance the maintenance process. mechanical systems are essential in a variety of industries, including manufacturing and aerospace. ensuring optimal performance and minimising downtime are essential factors for achieving efficient operation in these sectors. this phenomenon is due to any potential defect in mechanical components, which can lead to a corresponding failure in the operational processes, ultimately affecting the overall efficiency and reliability of the system. consequently, the use of thermal cameras has become an effective tool for non-destructive testing (ndt) of defects in mechanical systems [18]. the capability of thermal cameras to sense the temperature on the exterior of mechanical components allows them to detect potential defects at an early stage [19]. in addition, thermal cameras can continuously monitor and record the temperature of mechanical components whilst they are in operation. this capability enables the identification of heat-related issues caused by many factors such as wear and friction. standard cameras cannot detect these temperature variations. thus, the importance of thermal cameras in detecting defects in mechanical system components is widely considered. the reliability and longevity of mechanical systems are noticeably improved when mechanical issues are promptly identified and proactive maintenance strategies are implemented. insights gained from thermal imaging allow for effective preventative maintenance, enabling the timely servicing or replacement of components before they approach critical failure levels. the incorporation of thermal cameras within the framework of industry 4.0 and the internet of things (iot) [20] introduces novel opportunities for identifying faults in mechanical systems. intelligent and predictive maintenance systems can be developed by combining thermal imaging, sensor data and advanced analytics. these systems possess the capability to predict potential failures, optimise maintenance schedules and facilitate data-driven decision-making for the management of mechanical assets. 2.2 electrical systems electrical systems play a crucial role in numerous industries, including energy generation, delivery and circulation. detecting defects in these systems is essential for identifying potential issues such as damaged interconnections [21], strained circuitry [22] and heat-generating components [23]. thermal cameras are invaluable tools in preventing electrical malfunctions, improving energy efficiency and ensuring the reliability and safety of electrical systems. by identifying areas of elevated temperature, these cameras help pinpoint potential failures before they lead to more substantial problems [24]. all the thermal information obtained by thermal cameras can be recorded, allowing it to be monitored offline for onboard digital twin hussein n. al-jubori al-khwarizmi engineering journal, vol. 20, no.4, p.p. 7088 (2024) 74 applications as well as for offline digital twin systems [25]. hence, the application of thermal cameras is now recognised as a viable technique for detecting and diagnosing defects in electrical systems, thereby promoting preventive maintenance and minimising the likelihood of failures. the timely recognition of such defects enables immediate reconditioning measures, thereby preventing potential damage to equipment, electrical fires or interruptions in the power supply [26]. the application of a proactive approach advantageously reduces downtime and maintenance costs but also increases the operational lifespan of electrical equipment. along with reducing potential risks, thermal imaging also facilitates the identification of electrical components operating at high temperatures. furthermore, thermal cameras play a crucial role in the examination of electricity delivery and energy optimisation within electrical systems. by optimising energy consumption, these cameras substantially contribute to cost reduction, energy waste minimisation and overall improvement in the sustainability of electrical systems. during quality control and inspection processes, thermal cameras are invaluable tools. the incorporation of thermal imaging, sensors and advanced analytics can enhance smart supervision systems. these systems possess the capability to consistently evaluate the condition and operational efficiency of electrical components, detect deviations from normal behaviour and trigger notifications or automated actions as required. the incorporation of this technology improves the effectiveness of maintenance operations, reduces the likelihood of human error and enables the implementation of a predictive maintenance strategy. 2.3 structural materials buildings are constructed using various structural materials, which may develop defects under certain conditions. ensuring the safety of these buildings depends on detecting and addressing these defects [31]. thermal imaging technology is extensively used to identify defects in structural materials across different types of structures, including buildings [27], bridges [28] and pipelines [29]. by monitoring and investigating temperature changes on the surface, detecting issues such as leaks, moisture and structural deficiencies becomes practicable [30]. thus, thermal inspections serve as a valuable tool for evaluating structural integrity, detecting hidden flaws and expediting timely repairs or maintenance activities. researchers have widely utilised thermographic cameras for inspecting structural materials to identify obscure faults in the human eye. thermal cameras can help detect air breakthroughs or unfit insulation due to their capability to collect and detect energy emitted from surfaces of structural materials. the collected thermal variations are indicators of heat dissipation or absorption that may increase structural material discomfort. thermal cameras have facilitated insulation maintenance to improve thermal conditions and energy efficiency by detecting heat leaks. individuals using thermal cameras can detect numerous building faults. for instance, they can help identify damaged insulations that lead to uneven temperature distributions, high cooling and heating costs and energy loss. therefore, thermal cameras can help individuals offer regular building updates to enhance energy-saving effectiveness and cost reductions. individuals also find thermal cameras essential in detecting breakthrough moisture. structural materials contain water, thereby increasing their potential for corrosion, mould emergence and drop, which negatively impact buildings’ safety. with thermal imaging technology embedded into thermal cameras, individuals can detect temperature variations caused by moisture infiltration, helping to mitigate potential risks. typically, these temperature variations serve as a precaution for potential moisture breakthroughs, giving building managers or maintenance teams the opportunity to address the issue before it escalates. thermal camera imaging is also highly effective for detecting structural issues such as delamination, gaps or cracks in buildings. thus, temperature variations in buildings serve as indicators of hidden faults that require immediate attention to prevent potential hazards, including fatalities. the above information regarding thermal cameras is a crucial resource for professionals in the inspection and structural engineering fields. such information can help in assessing the severity of faults within buildings, enabling the development of effective strategies for reinforcement and repair to meet safety and structural integrity standards. 2.4 manufacturing and quality control different industrial players have applied thermal imaging technology to improve product process efficiency and meet quality control requirements. the technology helps manufacturing companies to produce quality goods, minimise waste and promote sustainable manufacturing operations, thereby meeting the requirements. with this technology, manufacturing firms can detect faults sufficiently early to avoid compromising customer satisfaction [32]. production and quality control in companies hussein n. al-jubori al-khwarizmi engineering journal, vol. 20, no.4, p.p. 7088 (2024) 75 have been substantially improved through thermal imaging technology, which offers non-destructive and non-contact methods for inspection. [33]. using this technology in cameras gives them the capability to detect temperature variations, which are key indicators of hidden irregularities that might affect product quality [34]. thermal cameras can detect hidden material flaws, including but not limited to insufficient bonding, cracks, delamination and porosity, by evaluating temperature fluctuations. if such faults are left unattended, then the performance and quality of products are more likely to be notably compromised, lowering customer satisfaction. therefore, the use of thermal cameras in the manufacturing sector aims to provide quality assurance and verification [35]. by examining thermal patterns using these cameras, firms can assess compliance, uniformity and consistency of products before they are released into the market for consumption. thermal imaging aids firms in detecting discrepancies in meeting desired quality standard by assessing variations in thermal signatures. this information is crucial because it allows entities to plan training programmes that raise awareness of compliance with quality standards, ensuring customer satisfaction and increased profits. in contrast, physical measurements or visual examinations used in conventional testing require disassembly and destructive sampling, methods that are associated with high material wastage and elevated costs [36]. with thermal cameras, non-destructive and noncontact testing can be performed on various materials and products without compromising their structural integrity. 2.5 non-destructive testing non-destructive testing (ndt) widely employs thermal imaging cameras to identify faults, including material cracks, inclusions or voids, without causing damage to the products. industries such as automotive, manufacturing and aerospace have adopted ndt techniques to ensure that their products meet safety and quality standards. these techniques are crucial in ensuring that the structures and materials produced are safe, reliable and of high veracity [37]. by using these techniques, companies can evaluate product components without the need for disassembly or causing damage. thermal cameras have become increasingly recognised in the ndt field as valuable tools due to their noninvasive and non-contact inspection capabilities, allowing for the detection of temperature fluctuations that indicate potential issues. these cameras use thermal imaging technology to identify anomalies such as separations, fractures, foreign materials and empty spaces [38, 39]. defects are often associated with varying thermal characteristics compared to the surrounding environment, creating detectable thermal variations that can be identified using thermal imaging technology. thermal cameras are also useful for studying material homogeneity, density and composition by analysing temperature distributions across surfaces, thereby helping to identify faults. in the field of ndt-related welding inspection, thermal cameras play an important role in evaluating weld joint quality by assessing thermal variations along the material. these variations can reveal possible faults, such as cracks, minimal fusion or porosity. inspectors in this field benefit from thermal imaging because it helps them detect temperature deviations in welded materials, highlighting the quality of the welding process. 2.6 pipeline inspection pipeline systems are considered critical infrastructures for loading different fluids across long distances, including water, gas and oil. therefore, pipeline safety must be consistently maintained to limit potential issues such as leaks [40]. particularly, thermal cameras are used to inspect pipelines to find leaks or defects by monitoring the temperature distribution along the pipeline. thermal inspections make it easier to identify problems, thereby improving the integrity and condition of pipeline systems [41, 42]. notably, using thermal cameras to inspect pipelines is an effective technology for monitoring defects and ensuring the safe functioning of these systems. the flow of fluids within the pipeline leads to temperature fluctuations on the pipe’s surface. thermal cameras are capable of detecting deviations in temperature and providing visual guidance to potential leakage points. the obtained data enables personnel to expeditiously detect and identify leaks, facilitating prompt repairs. hotspots may also indicate other issues in pipelines, such as the presence of localised fluid obstructions [43]. this information assists operators in identifying possible problematic regions and implementing appropriate remedial steps, such as investigating fluid flow problems, to prevent them from escalating into more substantial difficulties. thermal cameras are essential tools for monitoring and inspecting corrosion and erosion regions in pipelines [44]. over time, corrosion and erosion can weaken the strength of pipe walls, posing a risk to the overall structural integrity of the pipeline. with the timely identification of thermal fluctuations, hussein n. al-jubori al-khwarizmi engineering journal, vol. 20, no.4, p.p. 7088 (2024) 76 individuals can detect faults early and formulate maintenance strategies to address and prevent progressive failures. scholars have found thermal cameras beneficial in assessing the structural integrity of pipeline coatings. these coatings often protect pipes from corrosion and other forms of damage. however, coatings may deteriorate over time due to the effect of mechanical issues (stress) or environmental conditions. in these circumstances, thermal cameras become crucial tools, as they assess temperature variations caused by coatings faults (such as inadequate coverage or delamination). using temperature deviation visualisations, individuals can identify specific areas on pipes or walls where coatings have been compromised, allowing for targeted evaluations and repairs to maintain the protective integrity of the coatings. inspecting insulated or underground pipes is made more efficient and non-intrusive with thermal cameras, which are capable of identifying hidden problems. integrated thermal imaging technology detects thermal fluctuations on the exterior of pipes or their insulation, helping to locate faults, leaks or hot spots. the data collected from thermal cameras can be used for continuous monitoring of the conditions of pipes, eliminating the need for excavation or disassembly. 2.7 fire protection fire is a significant hazard to humans, animals, birds, tangible assets and the surrounding environment. the early detection of fire is vital because it expedites effective suppression and management of associated fire incidents. the enhancement of fire alarm systems and fire prevention instruments may be realised through their integration in environments characterised by substantial heat generation. thermal imaging cameras are used inside fire protection systems to detect thermal irregularities, facilitating the rapid identification and control of flames. thermal cameras are increasingly becoming recognised as essential tools in fire detection systems due to their capability to provide improved capabilities for early fire detection. the identification of temperature variations becomes possible by using thermal imaging technology, possibly serving as an indicator of fires [45]. in contrast to traditional smoke or flame detectors, thermal imaging technology assumes control over the identification of fires via the detection of heat fluctuations. this capability facilitates early detection before the sight of flames or smoke, which, in turn, enables fast response, including actions such as departure, putting out fires and control measures, reducing the likelihood of fire spread. thermal cameras have shown notable use in the identification of fires that exhibit no apparent smoke or arise in environments with restricted visual perception [46]. the aforementioned characteristic provides thermal cameras with distinct advantages in situations where relying only on smoke detection may be inappropriate, such as in large open rooms, factories or high places. additionally, thermal cameras provide continuous fire detection during the day and night. furthermore, in contrast to human operators, thermal cameras are advantageous due to their resistance to tiredness or oversights, facilitating continuous monitoring of the area of interest for temperature irregularities. the continuous monitoring system ensures rapid identification and resolution of fires, even in situations where human supervision is impractical. thermal cameras allow individuals to acquire thermal images to use in identifying the amount and the exact location of a fire to guide the actions of emergency responders towards improved fire suppression efforts. 2.8 automotive and aerospace industries the aerospace and automotive industries are increasingly adopting thermal cameras in detecting defects. these cameras can identify faults in the engine, the braking system, the exhaust system and other components. through routine thermal inspection in the two industries, safety and performance have been improved as maintenance costs have been minimised. the sectors remain strict on surveillance and assessment of procedures to ensure safety is prioritised and commodities are effective and reliable. the thermal imaging technology on thermal cameras allows individuals to capture temperature fluctuations, indicating suboptimal functioning or irregularities linked to engines [47]. thermal cameras also use embedded thermal imaging technology to monitor the cooling and exhaust systems of the engine to detect parts with high temperatures, leaks and other areas of concern to guide the maintenance team towards performing timely procedures to promote safety. data from such evaluations assists engineers in assessing engine performance and efficiency. thermal cameras have also been widely applied in thermal analysis and mapping of the aerospace and automotive industries [48]. these cameras can visualise temperature variations, allowing for the generation of thermal maps of various systems and components, including the propulsion, electrical and braking systems. thermal maps allow engineers to study heat distribution to various systems and components, thereby identifying areas of concern hussein n. al-jubori al-khwarizmi engineering journal, vol. 20, no.4, p.p. 7088 (2024) 77 and those with a high risk of overheating. such collected data serves as the starting point for the optimisation of component designs, heat dissipation and thermal insulation and thermal veracity. the thermal cameras help identify and assess automotive and aerospace malfunctions. the thermal imaging technology aids the cameras in identifying temperature irregularities, which could indicate additional problems. the industry players also use the tic to detect problems such as defective wiring, malfunctioning sensors and overheating of electrical connections. using their non-invasive capability, thermal cameras rapidly identify faults, thereby diminishing operational interruptions and augmenting maintenance procedures. thermal cameras equally help ascertain thermal and human comfort in the automotive and aerospace design domains. they also use thermal imaging technology to assess temperature distributions and thermal and human comfort levels within vehicle or aircraft cabins. such information is vital in optimising air conditioning, ventilation and heating systems to ensure comfortability and safety of humans in those cabins, increasing their satisfaction. human factors are also examined using thermal cameras in the cockpit design and seating areas to optimise ergonomic designs of the aerospace and automotive interiors and enhance comfort. 3. thermographic cameras effectiveness thermographic cameras, which have been applied across numerous domains, have been proven effective. as shown in figure 2, various factors that contribute to the effectiveness of thermographic cameras are explored in this section, and their benefits over conventional inspection approaches are clarified. fig.2. thermographic camera factors a major benefit of thermography cameras lies in their non-destructive and non-contact assessment capability. they can record various thermal patterns and temperature fluctuations without having direct contact with the item being examined. in contrast, conventional inspection techniques require close contact with the item or material under investigation. notably, thermography cameras are useful in understanding the faultiness of sensitive and fragile constructions or materials because their non-destructive nature guarantees that the item would remain undamaged. these cameras have made it possible to conduct real-time and rapid inspections to identify abnormalities in items or materials [49]. in the contemporary market, the latest thermography cameras are faster at collecting data and offer high-resolution thermal image capabilities due to advancements in technology. with these capabilities, operators and other inspectors can quickly identify problems in materials, accelerating the pace of inspections and facilitating prompt resolution of issues. some industrial processes and operations, especially in dynamic contexts, require real-time monitoring to detect anomalies. in these cases, thermography cameras are invaluable because they provide continuous, real-time monitoring. these cameras have found widespread use across different domains, including environmental monitoring, electrical inspections, medicinal applications, building inspections and mechanical system diagnostics. they are useful in these fields due to their capacity to help individuals detect varying thermal patterns and temperature changes, raising the curiosity of wanting to investigate systems and materials further for abnormalities, inefficiencies or defects. resolution and sensitivity have been enhanced in the current thermography cameras, guaranteeing thorough and precise system and material evaluations. owing to their increased sensitivity, the cameras can record thermal variations per minute, improving their capability to aid in the identification of small abnormalities. based on their superior resolution, thermography cameras capture detailed and accurate thermal images of thermal patterns and temperature distribution in systems and materials. the resolution and sensitivity of the thermograph cameras determine their capability to assess problems in various applications. these cameras have become increasingly popular in fault detection because they support quantitative and qualitative analyses [50]. hussein n. al-jubori al-khwarizmi engineering journal, vol. 20, no.4, p.p. 7088 (2024) 78 individuals have found the cameras excellent in using refined image processing software and algorithms to transform thermal images into useful data (thermal gradients or readings). through quantitative analysis, thermal cameras can accurately and impartially detect thermal variations, enabling more informed decision-making. their capability to read and analyse data in real time allows them to efficiently identify problems and guide individuals in pinpointing their root cause. 4. defect detection techniques many industrial players conduct thorough investigations to identify defects in their systems and materials using various approaches, including but not limited to image processing algorithms and temperature analysis. the advancement of thermography camera technology, its superior resolution and its capability to integrate imaging modalities have been key topics of discussion. through its non-destructive techniques, thermal cameras offer considerable advantages in identifying defects in various constructions and materials. the following section highlights and elaborates on the common thermography defect detection techniques. 4.1 active thermography active thermography is known to apply external energy sources, such as heat, to trigger a thermal reaction in materials under investigation. this approach is widely used because it helps discover underlying faults that the human eye may overlook. lock-in and pulsed thermography are two commonly applied active thermography methods [51]. in pulsed thermography, a material’s surface is exposed to a heat pulse, and the thermograph camera records the reaction. thermal responses occur due to changes in the heat transmission mechanism caused by abnormalities. normally, inclusions, delamination and voids can be identified from thermal images taken before and after the heat pulse. in lock-in thermography, the modulation frequency is synchronised with the thermography camera’s capture rate whilst applying a controlled light or heat source to the targeted substrate. this approach enhances flaw detection by isolating the thermal response of the faults from the background noise. the approach is vital for identifying underlying faults in metallic structures, such as concealed corrosion or fractures. 4.2 passive thermography passive, ambient or natural thermography relies on thermal variations in materials to identify faults without an external energy source. the technique applies the surface temperature variations to determine material faults. this approach is often used in electrical inspections, quality control and building inspections [52]. the method applies thermal contrast analysis in examining surface thermal variations to identify faults in materials. the different faults, such as cavities, hotspots or fractures, which are linked to distinct temperature changes and can be identified from thermal images, help analyse materials and draw conclusions. thermal contrast analysis is commonly used in electrical connection inspections to identify overheating components and in building inspections to detect moisture incursion. infrared imaging is a widely used passive thermography technique that captures images of temperature variations in materials. this technique relies on detecting temperature fluctuations to identify faults such as thermal bridging, air leaks and insulating gaps. this method is particularly effective for moisture detection, building energy audits and insulation assessments due to its superior spatial resolution. 4.3 combined techniques in some cases, passive and active thermography techniques can be combined to ensure thorough fault detection. when combined, the two approaches aid in detecting a greater variety of flaws, thereby increasing the precision of defect characterisation. transient thermography merges the benefits of passive and active thermography techniques by introducing a heat pulse and recording the consequent thermal reaction of materials. the combined method is commonly used in inspecting composite materials, evaluating aerospace components and inspecting concrete structures to identify subsurface and surface faults. vibrothermography is employed to capture thermal images whilst inducing vibrations in materials. flaws in materials often affect their thermal reactivity, resulting in varying thermal patterns. for composite materials, coatings and adhesives, vibrothermography can easily detect bonding/debonding/delamination. table 1 displays a comparison of the thermography techniques. hussein n. al-jubori al-khwarizmi engineering journal, vol. 20, no.4, p.p. 7088 (2024) 79 table 1 main features of thermographic camera techniques 5. discussion thermographic cameras have numerous benefits compared to traditional inspection methods across different industrial domains. this section discusses the key findings and implications of using thermographic cameras for defect detection, as well as potential challenges and areas for future research. thermographic cameras possess various advantages that substantially enhance their effectiveness in detecting defects. thermographic cameras facilitate non-invasive and contactless examinations, thereby safeguarding the structural soundness of the scrutinised entity whilst offering remarkable revelations regarding its state. this advantage is of considerable importance, especially when dealing with delicate or sensitive materials and structures. thermographic cameras offer efficient and instantaneous defect detection capabilities in real time. the rapid capture of temperature variations and thermal patterns using this technology facilitates the prompt detection and evaluation of defects, resulting in reduced inspection durations and facilitating the timely implementation of corrective measures. figure 3 depicts the thermal image obtained by an flir t335 camera at the workshop of the ministry of higher education, university of baghdad, automated manufacturing department of a 3d printer’s heater whilst the 3d printer is running. notably, the temperature range of the obtained region is between 26.8 °c and 109 °c. another example of the capability of a thermal image to monitor high temperatures, as shown in figure 4, is obtained using an flir t335 camera at a workshop of the ministry of higher education/university of baghdad/automated manufacturing department, which was used whilst the furnace was running and the temperature of the obtained region ranged between 35.6 °c and 263 °c. thermography techniques method key features applications active thermography uses an external energy source (heat or light) to induce a thermal reaction in the material. pulsed thermography: brief heat pulse to surface, records thermal response for flaw detection. lock-in thermography: synchronises camera with modulated heat or light source for improved flaw detection. finding underlying flaws such as delamination, voids or inclusions. passive thermography relies on detecting natural or ambient temperature fluctuations in the material without an external energy source. thermal contrast analysis: examines surface temperature changes to identify thermal differences caused by defects. infrared imaging: measures material surface temperature variations for abnormality detection. quality control, building inspections, electrical inspections, moisture detection, insulation evaluations and energy audits. combined techniques integrates active and passive thermography methods to enhance flaw identification capabilities. -transient thermography: uses brief heat pulse and records subsequent thermal reaction over time for comprehensive analysis. vibrothermography: utilises thermal imaging with induced vibrations to detect flaws. inspection of composite materials, testing of aerospace components, assessing concrete structures and specific fault identification in structures or materials. hussein n. al-jubori al-khwarizmi engineering journal, vol. 20, no.4, p.p. 7088 (2024) 80 fig. 3. capturing thermal image of 3d printer heater fig. 4. capturing thermal image of furnace online weld quality monitoring is realised using thermal image analyses to automatically identify defects. the temperature variance was computed for each row and column. figure 5 displays the variance plot. the temperature variance was computed for each individual pixel in the row and column. the resulting values are presented in the provided figure. these statistical graphs facilitated the identification and localisation of anomalies. fig. 5. variation in a thermogram frame [53] figure 6 illustrates the contrast between a thermograph picture of a healthy induction motor and a thermograph image of a damaged induction motor. these differences allow for the application of an analysis. the video underwent analysis using the commercial programme flir researchir max to extract the temperatures within the specified zones. considering the high volume of data in the video (30 frames per second), an analysis was conducted on a per-minute basis, assuming that the temperature remains constant without abrupt hussein n. al-jubori al-khwarizmi engineering journal, vol. 20, no.4, p.p. 7088 (2024) 81 changes. two different supply frequencies, 40 and 60 hz, were used to examine their behaviour. these frequencies were programmed or set up in the frequency inverter. the zones were examined, and the graphs were generated, as shown in figure 6. fig. 6. thermograph image of the induction motor: (a) no defect; (b) damaged [54] steel fracture detection often relies on visionbased methods. identifying any surface imperfections becomes possible when analysing the images captured by the camera. photographic images are inherently limited in their capability to appropriately reveal the interior aspects of things. as presented in figure 7, fractures in steel sheets can be identified by integrating cnns with infrared thermal imaging. fig. 7. convolutional neural networks with infrared thermal imaging [55] thermographic cameras have demonstrated their versatility as multifaceted instruments, exhibiting utility across diverse industries, including manufacturing, construction, electrical systems and aerospace. the adaptability of thermographic cameras to various materials, structures and types of defects is emphasised by their versatility. the progress in thermographic camera technology has resulted in enhanced sensitivity and resolution, facilitating the identification of minimal temperature fluctuations and the augmentation of the precision and intricacy of thermal images. such an improvement is crucial because it will elevate fault detection and characterisation in systems and materials. thermographic cameras are beneficial in detecting and characterising system or material faults. however, recognising and addressing the limitations of these cameras is crucial. the emissivity and reflective properties of materials under investigation impact the effectiveness of the thermographic camera to a large extent. surfaces with low emissivity and high reflectivity are likely to alter thermal patterns, diminishing the capability of the camera to assist in fault detection. remedial actions (using emissivity correction methods or anti-reflective coatings) are required under such circumstances. thermal image interpretation requires appropriate analysis techniques and expertise. during thermal image interpretation, the camera settings, environmental conditions and material properties must be considered to attain precise and accurate fault detections and characterisations. substantial data could be extracted from the thermal images by applying sophisticated software and algorithms. the standardisation and calibration of thermographic cameras are crucial in ensuring that defect detection achieves high precision and is satisfactorily dependable. regular camera calibration and strict compliance with standardised protocols are necessary to achieve high result compatibility and consistency. the development and implementation of industrial-wide measures and standards to guide defect detection and thermographic camera calibration are critical in ensuring reliable and consistent inspection results. future research should focus on prioritising camera resolution in various aspects. advancements in image processing methods are expected to augment the fault detection capabilities of thermographic cameras. similarly, the advancement of algorithms to facilitate automatic flaw detection, quantitative image analysis and image fusion is expected to optimise the accuracy and precision of flaw detection. integrating thermographic cameras into x-rays or visual inspections is expected to provide hussein n. al-jubori al-khwarizmi engineering journal, vol. 20, no.4, p.p. 7088 (2024) 82 complementary and comprehensive flaw detection capabilities. further investigations into different inspection methods could help improve the reliability and precision of fault identification. various materials exhibit varying response characteristics due to distinct thermal properties. further research in the development and advancement of flaw detection through thermographic cameras is also expected to improve methodologies aimed at addressing specific material needs, thereby improving their efficiency. inspection process optimisation can be released by understanding the thermal properties of materials and tailoring them to an appropriate flaw detection technique. performance evaluations in real-world situations are critical in assessing the effectiveness of the flaw detection methodology when thermographic cameras are adopted. in this regard, a comprehensive field testing and validation experiment should be implemented. the experiment should consider the different types of flaws; cameras should be tested using various materials and in different environmental conditions. this experiment is expected to elucidate the suitability and barriers to thermographic camera use in studying real-world defect situations. thermal data interpretation and the potential avenues for ensuring automated abnormality detection have been reviewed. the literature review has contributed to the field of thermographic camera technology and its techniques, emphasising the need for additional research aimed at improving the availability and effectiveness of the ndt approach. the thermal camera applications highlighted in this review revealed the application of thermal imaging technology for detecting flaws in systems and materials in different industrial domains, as shown in table 2. thermal cameras are crucial in proactive maintenance, achieving enhanced product quality and improving safety across diverse sectors by effectively detecting thermal irregularities and identifying concealed flaws. table 2 summary of the applications of thermal cameras in defect detection application description electrical systems detects loose connections, overloaded circuits and overheating components in electrical systems mechanical components identifies defects such as bearing faults, misalignments and inadequate lubrication in machinery structural materials detects heat leaks, moisture intrusion and insulation deficiencies in buildings and structures manufacturing and quality control identifies defects such as cracks, delamination and voids in products during manufacturing processes non-destructive testing (ndt) detects defects such as cracks, voids or inclusions in materials without damaging the inspected object pipeline inspection identifies leaks, blockages and temperature anomalies in pipelines, ensuring their integrity fire protection detects heat sources and anomalies for early fire detection and prevention automotive and aerospace industries detects faults in critical components, optimising performance and improving safety table 2 summarises various thermal camera applications in the fault detection domain. specific domains where this technology has been applied, along with the types of faults it has been used to detect, have been highlighted. various industries have demonstrated the efficacy of thermal cameras in detecting flaws. these cameras have been utilised in detecting and displaying thermal energy emissions from materials, which helps in identifying various flaws. various findings regarding the use of thermal cameras in flaw detection have been documented. they provide supplementary capabilities for evaluating temperature variations to detect defects such as excessive heat, insulation inefficiencies, structural defects and leakages. individuals can use thermal cameras to identify flaws and direct their actions to reduce them, thereby enhancing the overall reliability and accuracy of systems. through contactless and non-invasive approaches, thermal cameras can detect flaws without damaging systems or materials. as such, they help avoid direct physical contact with the materials under inspection, preventing interference with ongoing activities that could jeopardise performance and accuracy. moreover, the ndt capabilities embedded in thermal cameras allow for the evaluation of crucial structural components whilst conserving their integrity. with thermal cameras, individuals and entities can detect flaws earlier, facilitating proactive approaches towards timely and continuous maintenance. such proactive approaches help minimise costly downtime and breakdowns. prompt fault detection is essential because entities have the opportunity to implement hussein n. al-jubori al-khwarizmi engineering journal, vol. 20, no.4, p.p. 7088 (2024) 83 focused repairs, thereby enhancing financial savings, minimising potential safety risks and addressing minimal productivity. different industrial domains, including but not limited to pipeline inspection, electrical systems, mechanical components, manufacturing and structural materials, have witnessed thermal camera applications. the adaptability of the systems requires firms to identify faults across different environments to tailor specific assessments and action points towards addressing the faults for enhanced productivity. thermal cameras support various technology integrations, such as 3d imaging, ai and image processing algorithms, augmenting the capabilities of defect detection. such integrations ensure the cameras perform automated fault detection, improving the precision and accuracy of the results. the use of thermal cameras to detect faults is a critical starting point for improving the safety and reliability of materials and systems across different industrial domains. they play a vital role in accident prevention, preserving structural integrity and mitigating risks by identifying various hazards, such as structural weaknesses, electric faults and mechanical failures, which could worsen if left unattended. 6. conclusions different industries have applied thermal cameras to detect material or system defects. through the use of non-destructive properties, hidden fault discovery and improved detection accuracy and performance, industries have realised reduced maintenance costs, substantial financial savings, heightened safety and reliability. future research into defect recognition algorithms and advancements in thermal camera technology is expected to further enhance the capabilities of thermographic cameras, expanding their application in fault detection. the advantages of using thermographic camera-based defect detection are evident across a wide range of applications. mechanical systems have revolutionised flaw detection and maintenance across industries using thermal cameras. thermal cameras can detect early anomalies, enable non-destructive testing and facilitate predictive maintenance, making them essential tools for improving the dependability, security and effectiveness of mechanical systems. the integration of technologies such as the iot and industry 4.0 can further improve defect detection and asset management. this integration will improve mechanical systems across industries. thermal cameras in electrical systems have also revolutionised defect detection, preventive maintenance and risk reduction. they can identify flaws, assess structural soundness and improve energy conservation in structural materials. additionally, these cameras reveal heat leaks, moisture intrusions, insulation issues and other irregularities. in manufacturing and quality control, they help identify defects, monitor processes and ensure quality. thermal imaging technology reduces waste and promotes sustainable manufacturing due to its non-destructive nature. in ndt, thermal cameras help identify defects and corrosion and can execute structural evaluations and material analyses. they can also detect leaks, hotspots, corrosion, buried or insulated pipelines and examine coating integrity. thermal cameras in fire detection systems improve fire detection, especially in low-smoke or low-visibility environments. in the automotive and aerospace industries, they are useful for engine and component testing, thermal mapping and analysis, fault detection and diagnosis, composite material inspection, thermal comfort and 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[55] j. yang, w. wang, g. lin, q. li, y. sun and y. sun, "infrared thermal imaging-based crack detection using deep learning," in ieee access, vol. 7, pp. 182060-182077, 2019, doi: 10.1109/access.2019.2958264. https://doi.org/10.1002/stc.2506 https://doi.org/10.1016/j.jmatprotec.2012.03.002 (2024) 70-88، صفحة 4، العدد20مجلة الخوارزمي الهندسية المجلد حسين ناجح حميد 88 اكتشاف العيوب باستخدام تقنيات كاميرا التصوير الحراري: مراجعة األدبيات 3جربي سامح ، 2عزة عبدالرزاق عبدالكريم ،*1حسين ناجح حميد 2،1 قسم هندسة التصنيع المؤتمت، كلية الهندسة الخوارزمي، جامعة بغداد 3 كلية الهندسة، جامعة الحائل، المملكة العربية السعودية hussein.najeh2204@kecbu.uobaghdad.edu.iq*البريد االلكتروني: ةالخالص المثال ال الحصر، بسبب التقدم في تكنولوجيا مستشعرات التصوير الحراري, تستخدم الكاميرات الحرارية في مختلف المجاالت، بما في ذلك على سبيل األدبيات الحالية الزراعة والطائرات بدون طيار واألدوية والتصنيع، ومن أجل تحقيق أهداف مختلفة تتعلق بالسالمة واألمن. في هذه الدراسة سيتم استكشاف لحماية من الحرائق، والتصنيع، والفضاء بعمق لتوضيح تطبيقات كاميرات التصوير الحراري في اكتشاف األخطاء في مجموعة واسعة من التطبيقات، مثل ا لى فعالية كاميرات والسيارات، واالختبارات غير المدمرة، وصناعات المواد اإلنشائية. تتوسع المناقشة الحالية حول نتائج الدراسات السابقة، مع التركيز ع بشرية. تم عرض طرائق مختلفة للكشف عن العيوب، بما في ذلك تحليل التصوير الحراري في التمييز بين العيوب غير القابلة لالكتشاف من خالل الرؤية ال عند مقارنتها درجة الحرارة وخوارزميات معالجة الصور، بدقة. ثم تمت دراسة العوامل التي تسهم في فعالية كاميرات التصوير الحراري وتوضيح مميزاتها .ير الذي أحدثته تقنية الكاميرا الحرارية في اكتشاف أخطاء النظام الميكانيكي لتحسين الصيانةبطرائق الفحص التقليدية. أشارت هذه الدراسة إلى التحول الكب ال غنى عنها لضمان نظًرا ألن هذه الكاميرات يمكنها تحديد المخالفات غير المرئية والسماح باالختبارات والصيانة العملية للنظام، فقد تطورت لتصبح أدوات بكفاية وموثوقية وبقائها آمنة. واشارت الدراسة ايضا انه يمكن تحسين التكنولوجيا الكاميرات الحرارية بشكل أكبر من خالل الجمع عمل األنظمة الميكانيكية ائية، مكنت وإنترنت األشياء، مما يضمن أداًء مرتفعًا للنظام الميكانيكي عبر المجاالت المختلفة. عند استخدامها في األنظمة الكهرب 4.0بين تقنيات الصناعة ة الهيكلية، يمكن الكاميرات الحرارية األفراد من تحديد األخطاء للتخطيط للصيانة المبكرة التي ترمي إلى تخفيف المخاطر. بفضل قدرتها على تقييم السالم .للكاميرات الحرارية تحديد أوجه القصور في الحرارة والعزل، مما يؤدي إلى تحسين كفاية استخدام الطاقة mailto:hussein.najeh2204@kecbu.uobaghdad.edu.iq https://doi.org/10.22153/kej.2024.03.002 <4d6963726f736f667420576f7264202d20dfd1c7d120c8c7e5d120e6dec7d3e320e6dae3c7cf32392d203432> this is an open access article under the cc by license : al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 18, no. 2, june, (2022) p. p. 2942 comparative study of vibration analysis in rotary shafts between rayleigh's and dunkerley's methods karrar baher * qasim a. atiyah ** imad a. abdulsahib*** *, **, *** mechanical engineering department / university of technology / baghdad / iraq *email: me.19.20@grad.uotechnology.edu.iq **email: 20044@uotechnology.edu.iq ***email: 20018@uotechnology.edu.iq (receive 2 marh 2022; accepted 18 may 2022) https://doi.org/10.22153/kej.2022.05.001 abstract the importance of vibrations in rotating rotors in engineering applications has been examined, as has the best approach to interpreting vibration data. the most extensively used analytical approaches for rotating shaft vibration analysis have been investigated. in this research, a detailed study was made of the rayleigh and dunkerley methods due to their importance in the special calculations to find the amplitude of vibrations in the rotation system. the multi-node method was used to calculate both dunkerley's and rayleigh's methods. an experimental platform was built to study the vibrations that occur in the rotating shafts, and the results were compared with theoretical calculations and with different distances of the bearings. it proved that there is very little error between the experimental and theoretical results. the vibration signal from the sensors was analyzed using the labview program. rayleigh's method was compared to the exact method, and it was considered the most accurate method. it was found that it made very little difference, up to about 0.06%. as for the dunkerley method, the difference between it and the proper method is about 4%, which is acceptable. then a comparison was made between rayleigh's and dunkerley's methods, and it was found that dunkerley's method is the most appropriate in the calculations. keywords: vibrations, rotating-bearing system, rayleigh, dunkerley, labview. 1. introduction rotordynamics is the study of the dynamics of rotating machines. rotordynamics varies from structural vibration research because of gyroscopic moments, cross-coupled forces, and the possibility of whirling instability [1]. many industrial applications, including onboard space vehicles, revolving machinery in electrical power plants, and power transmission gear trains, utilize rigid rotor systems aided by linear or nonlinear elastic bearings. in rotating systems vibration can cause inefficiency, malfunction, and even catastrophic failure. as a result, modeling and understanding their complex behavior has become a prominent study topic [2-4]. a rotor-bearing mechanism can show undesirable subcritical super-harmonic resonances when the rotor's spinning speed is a part of its natural frequency [5]. vibration is a natural occurrence in rotating machinery, but it has the potential to reduce productivity [6, 7]. thus, while investigating the work of machines in general (and rotating machines in particular), vibrations are a serious concern for designers, engineers, and researchers. as a consequence, the focus will be on studying vibrations, determining the most appropriate method of analysis, and determining the values of critical frequencies arising from an imbalance in machines. mass imbalance is the most common cause of harmonic excitation in rotating machinery. an karrar baher al-khwarizmi engineering journal, vol. 18, no. 2, p.p. 2942 (2022) 30 imbalance can arise during the assembling of machine components or during the manufacturing process of machine components. even if a rotor is adequately balanced when it first starts up, its stability will diminish over time. another vibration response, such as vibration from a nearby unbalanced rotating machine, could be excited at the base of a spinning machine with its own mass imbalance oscillation [2]. one of the most common causes of machine vibration is the inertia of the machine's moving elements. in a reciprocating motion, several components move back and forth. newton's laws require that a force is applied to accelerate the mass, as well as a response from the force to the machine's structure. periodic deflections are perceived as vibrations because the forces are generally periodic [1]. tiwari [8] proposed a well-conditioned recognition technique for simultaneous calculation of residual imbalances, bearing stiffness, and damping coefficients based on the rotor's clockwise and counter-clockwise reactions. reddy and srinivas [9] investigated the dynamic analysis of a rotor with base excitation. with time histories, phase diagrams, and frequency responses, the effect of base excitation frequency and amplitude on rotor dynamics is demonstrated. wang et al. [10] focused on the imbalance reaction, and they proposed an algorithm for detecting residual imbalances in the rotor and bearings at the same time. the rotor was represented as a homogenous and continuous rayleigh beam. yang and colleagues [11] used a new sort of tvrbse based on the formulation of absolute node coordinates and rayleigh beam theory under an arbitrary lagrange-euler description to develop a dynamic model of a moving and axially rotating rayleigh beam. zhu and j. chung [12] used the proposed dynamical model to investigate the vibration and stability of a rotating rayleigh beam with axial motion. to completely consider the terms of rotating inertia, they used the rayleigh ray theory. farshbaf zinati, r., et al. [13] analyzed the stabilization and nonlinear vibration of a simply supported axially moving rayleigh viscoelastic beam fitted with intermediate nonlinear support. aouadi, m. a., & lakrad, f. [14] discussed the three-dimensional bending linear free vibrations of rotating rayleigh beams. the destabilization of free vibrations was found to be dependent on the linearization method that was used. faraji muhairi, m, et al. [15] studied the effect of angular velocity on the balance and vibration of a simply supported rayleigh shaft. the distinctions between the rayleigh and eulerbernoulli models are presented. the influence of the slenderness ratio on the instability threshold and natural frequencies is seen. zhu and chung [16] addressed the beam's dynamic behaviors and properties, as well as a novel rotating beam model that is currently being implemented. the spinning beam's dynamic behavior and vibration frequency were compared in action. while examining the spinning beam, the rayleigh beam model was found to be more accurate than the euler-bernoulli beam model. tamrakar and mittal [17] used an impact hammer test to determine the system's fundamental frequencies, then determined the speed at which whirling occurs in the system. they used dunkerley's natural frequency approach to verify the experimental results. levy [18] has created an iterative technology based on dunkerley's method for delivering natural vibration frequencies to discrete systems at the same time. low [19] validated a dunkerley expression referring to a uniform beam holding several masses. when compared to the result associated with the original property equation, it is discovered that dunkerley's expression can yield a good approximation in general. due to the impossibility of conserving computational time, low strongly advised the dunkerley approach for beams transporting more than two masses at separate locations. rayleigh and dunkerley's approaches for analyzing vibrations have been utilized in prior studies, but without specifying which is better in the study or expressing a clear comparison between them. for this reason, it is necessary to clarify the two ways and choose which is the most appropriate in mathematical calculations for studying spinning machines and determining their frequency values. the amplitude of vibrations in rotational systems will be determined using the rayleigh and dunkerley methods in this paper. it will also rely on the multi-node approach to calculate each of the dunkerley and rayleigh methods, compare them to one another, then compare both ways to the precise method to determine which is more accurate and recommended to utilize. 2. mathematical analysis the stator, which supports the bearing, is frequently assumed to be stiff when modeling a karrar baher al-khwarizmi engineering journal, vol. 18, no. 2, p.p. 2942 (2022) 31 rotor device. in real-world applications, however, the rotor is frequently included in a more flexible structure, such as the framework of an aero-engine, which adds more compliance to the system and theoretically affects the influence of bearing nonlinearities [3]. 2.1 rayleigh’s method the rayleigh method for estimating the system's natural frequencies will be presented in this study. the system will be continuous, and you will be able to utilize this method to estimate the fundamental natural frequency of continuous systems [20]. it is critical to conduct a modal analysis of the rotors to avoid resonance during operation. a dynamic study of the rotating-shaft system under operating conditions is also necessary to assess the dynamic properties of the rotating system. by seeing the shaft as a spinning beam model, the system was mathematically modeled [21, 22]. fig. 1. simply supported beam with finite nodes the uniform beam for the number of nodes is shown in figure 1, and the masses for the nodes are computed using the following equations [23]: ��� � ��/2 � � �� ��2 … 1� �� � � � �2 � � ��� ���2 … 2� where � � 1, 2, 3, . . . , � ��� � � �� ��2 … 3� the moment of inertia for the uniform solid beam is: �� � �64 ∗ � … 4� it is possible to represent both the stiffness and the flexibility of a system's elastic behavior. the equations of motion for normal mode vibration in terms of stiffness k [23]: !"#$%& � $'&�()* � 0 … 5� in the stiffness conception, the force is expressed as a displacement: (-* � $'&()* … 6� stiffness is the polar opposite of flexibility. the displacement is given in units of force in this case: ()* � $'&.�(-* … 7� ()* � $0&(-* … 8� the 0�,2 coefficients of the flexibility matrix are 3)�)#⋮)5 6 � 70�� 0�# ⋯ 0�50#� 0## ⋯ 0#5⋮ ⋮05� 05# ⋯ 055 9 3:�:#⋮:5 6 … 9� the flexibility influence coefficient 0�,2� is the bending at i due to a unit load exerted at j with all other forces equal to zero. deflections associated with :� � 1 and :# �:< � 0 are represented in the preceding matrix's first column. in the second column, you'll find deflections for :# � 1 and :� �:< � 0, and so on [23]. by multiplying eq. 5 by $'&.� � $0& , it is simple to determine the equation of motion in terms of flexibility: !"#$0&$%& � $�&�()* � 0 … 10� where, ()* is deflection vector matrix $�& is mass matrix $0& influence coefficient matrix equal $=&.� $=& is stiffness matrix $�& is unit matrix, '.� ∗ ' >! 1"# $�& � $0&$�&> … 11� when a lumped-mass system has a diagonal mass matrix, eq. 11 becomes. karrar baher al-khwarizmi engineering journal, vol. 18, no. 2, p.p. 2942 (2022) 32 ?! 1"# 71 0 ⋯ 00 1 ⋯ 0⋮ ⋮0 0 ⋯ 19 � 70�� 0�# ⋯ 0�50#� 0## ⋯ 0#5⋮ ⋮05� 05# ⋯ 055 9 7�� 0 ⋯ 00 �# ⋯ 0⋮ ⋮0 0 ⋯ �5 9? � 0 … 12� fig. 2. load exerted between the two bearings on a simply supported beam. figure 2 shows a simply supported beam with an applied load, from which the deflection equations for beams can be derived. the deflection will be as shown in figure 2: 02� � @bc l# ! b# ! c#� 6eil⁄ … 13� 0�� � @a#i# 3eil⁄ … 14� 0j� � @ad l# ! a# ! d#� 6eil⁄ … 15� now the fundamental natural frequency of the beam is calculated based on equations 9 and 13 to 15. )� � -� ∗ 0�� � -# ∗ 0�#� -< ∗ 0�<�. . . �-5 ∗ 0�5 )# � -� ∗ 0#� � -# ∗ 0##� -< ∗ 0#<�. . . �-5 ∗ 0#5 )5 � -� ∗ 05� � -# ∗ 05#� -< ∗ 05<�. . . �-5 ∗ 055 … 16� where � � ∗ l. the fundamental natural frequencies are obtained using equation 16 for a deflection given to several nodes in the simply supported beam. rayleigh's methods could be used to estimate the fundamental frequency of a beam or shaft defined by a series of lumped masses. the resulting constant deviation curve will be taken into account for weights %�l, %#l, %<l, ... which correspond to )�, )#, )<, ... deviations. the stored energy in the beam due to strain is [21] mnop � 12 l %�)� � %#)# � %<)< � ⋯ � … 17� '. q � 12 "# %�)�# � %#)## � %<)<# � ⋯ � … 18� mnop � '. q … 19� "# � l∑%�)�∑%�)�# … 20� 2.2 dunkerley’s method dunkerley's method uses the natural frequencies of the constituent elements to derive the fundamental frequency of composite construction. it is acquired by leveraging the fact that the higher natural frequency bands of practically all vibrating systems are large in comparison to their fundamental frequencies. the frequency equation can be used to determine eigenvalues for a large system of degrees of freedom [20]: the simplification procedures are done on equation 12, and then the formula is expanded to get the following formula: 1"�# � 1"## �. . . � 1"5#� 0����� 0##�#� . . . �055�5 … 21� because the intermediate frequencies "#, "<, …, "5 are often significantly larger than the fundamental frequency "�, and therefore karrar baher al-khwarizmi engineering journal, vol. 18, no. 2, p.p. 2942 (2022) 33 1"�# ≪ 1"�# � � 2,3, . . . , � 1"�# ≈ 0���� � 0##�#� . . . �055�5 … 22� this equation is referred to as dunkerley's formula. eq. 22 produces a fundamental frequency that is never exactly the same as the exact number. in some cases, it would be easier to rewrite eq. 22 as: 1"�# ≈ 1"�5# � 1"#5# �. . . � 1"55# … 23� where "�5 � 1 ∕ 0������/# � =�� ∕����/# is the natural frequency of a singledegree-of-freedom system with mass �� and a stiffness spring =�� , � = 1, 2, …, n. the lowest frequency of elasticity systems is calculated using dunkerley's method. 3. experimental work for this project, an experimental test platform was built to measure natural frequencies and take vibration readings. the main iron platform, which is a metal plate constructed of iron with dimensions of 120 cm x 40 cm x 5 mm that serves to carry the other parts was employed. a shaft is a spinning member that transmits rotational motion in the system. it is made of aisi 1045 steel and measures 80 cm in length and 20 mm in diameter. two metal iron pieces, 40 cm long, 10 cm wide, and 10 mm thick were also used. the major role of these components is to support the pillow block bearing. in addition to being placed on the linear ball bearing block to modify the distances between the bearings, these pieces have a longitudinal groove targeted at balancing devices and removing misalignments. there's also a linear sliding rail that holds the linear ball bearing block. its job is to vary the distance between the bearings depending on where the measurements are to be made. the system also has a ball bearing, (model ucp 204) made of cast iron with an inner diameter of 20 mm, a length of 124 mm, a thickness of 31 mm, a center height of 33.3 mm, and an overall height of 65 mm. a threephase electric motor with a capacity of 0.37 kw and a maximum speed of 2825 rpm was also used. a coupling’s main functions are to connect the shaft to the motor and reduce misalignment. it's also composed of iron, with a 43-mm outside diameter and a 98-mm length. the system also includes a power source for varying the motor's rotational speed, an arduino uno, and accelerometers mounted on a ball bearing to monitor the intensity of shaft vibrations, with measurements taken solely for the vertical axis. the details are shown in figures 3 and 4. the vibration signal from the two accelerometers (mpu6050 and adxl335), with a variable rotational speed starting at 500 rpm and ending at 3000 rpm, was analyzed using the labview program. as indicated in figure 5, the sensors (mpu6050 and adxl335) were also employed for the calibration process between them. the readings from the labview program are in hertz, and the system's frequency readings are taken on the z vertical axis. karrar baher al-khwarizmi engineering journal, vol. 18, no. 2, p.p. 2942 (2022) 34 fig. 4. the main components of the system. the main components of the system in this work as shown in figure 4: 1motor 2coupling 3ball bearing 4rotating shaft 5sensors 6main base 7linear ball bearing block 8linear sliding rail 9iron pieces 10arduino uno karrar baher al-khwarizmi engineering journal, vol. 18, no. 2, p.p. 2942 (2022) 35 fig. 5. calibration between mpu6050 and adxl335. 4. results and discussion the natural frequencies are derived using dunkerley's approach from the critical frequency values that were retrieved using equation 22 and the results are compared with rayleigh's uniform beam values, yielding the difference ratio between the two ways, as shown in table 1. given that rayleigh's technique is more precise, it's worth noting that as the number of nodes employed for the uniform beam grows, the difference between the values reduces and the results converge. this suggests that the two procedures are in karrar baher al-khwarizmi engineering journal, vol. 18, no. 2, p.p. 2942 (2022) 36 agreement and that the results are accurate. in practice, labview software will be used to find the frequency domain using mpu6050 and adxl335 sensors, with the two sensors being used to calibrate the results and note their reliability. the investigation was carried out in six distinct bearing positions. the amplitude of rotating shaft vibrations at six distinct places along the vertical z-axis was studied using the labview software in figures 7 to 12, and these positions are depicted in the simple schematic figure of figure 6. when the distance between the bearings is lowered, it has been noticed that the values of the natural frequencies begin to fall. at around 65 hz, the natural frequency reaches its maximum value, which is the first critical frequency of a spinning shaft in the first position. in the sixth position, it reaches its lowest critical frequency of 7 hz. the values of the natural frequencies usually decrease as the distance between the bearings decreases, indicating that when the shaft becomes a hanging shaft, the value of the stresses is lower which reduces the size of the whirling along the shaft. table 1, the frequencies of the uniform beam are calculated by using rayleigh-dunkerley's approach for a range of different nodes: the analytical approaches were investigated and compared to the exact method [20], with the rayleigh method showing a difference of 0.0585 percent when compared to the exact method, and with the dunkerley method showing a difference of 3.8788 percent when compared to the exact method. fig. 6. sketch between the bearings. (a) first position, (b) second position, (c) third position, (d) forth position, (e) fifth position, (f) sixth position. no. nodes natural frequency (hz) difference % rayleigh dunkerley 5 nodes 62.52421 60.22316 3.68025 7 nodes 62.77290 60.50608 3.61116 9 nodes 62.56431 60.11276 3.91845 12 nodes 62.56956 60.10748 3.93496 karrar baher al-khwarizmi engineering journal, vol. 18, no. 2, p.p. 2942 (2022) 37 fig. 7. natural frequency of first position. fig. 8. natural frequency of second position. fig. 9. natural frequency of third position. fig. 10. natural frequency of fourth position. karrar baher al-khwarizmi engineering journal, vol. 18, no. 2, p.p. 2942 (2022) 38 fig. 11. natural frequency of fifth position. fig. 12. natural frequency of sixth position. in addition, a comparison was made between the experimental and numerical sides, and a percentage difference was discovered, which was close, as shown in table 2. because real values exist on the experimental side and are more dependable in calculations and comparisons, there are values detected in the numerical and empirical aspects that are not found in the theoretical aspect that has been properly calculated. table 2, comparing the natural frequencies of the shaft numerically and experimentally. no. of position 1 2 3 4 5 6 1st natural frequency (hz) experimental 65.013 59.548 50.835 20.134 5.536 5.235 numerical 60.762 67.235 60.933 22.651 6.6278 4.889 difference % 6.996 11.433 16.572 11.112 16.473 7.077 2nd natural frequency (hz) experimental 125.845 155.435 105.735 93.648 100.153 35.686 numerical 141.88 141.88 99.612 111.11 118.38 35.656 difference % 11.301 9.553 6.146 15.715 15.397 12.325 3rd natural frequency (hz) experimental 200.146 230.233 155.084 120.875 130.478 120.235 numerical 220.82 237.23 141.88 141.88 141.88 141.88 difference % 9.362 3.047 9.306 14.804 8.036 15.256 the first five natural frequencies were compared in table 3 between the numerical and experimental sides using ansys. the values of the initial natural frequencies turn out to be close to a substantial extent, implying increased reliability. karrar baher al-khwarizmi engineering journal, vol. 18, no. 2, p.p. 2942 (2022) 39 table 3, comparison of natural frequencies experimentally and numerically by ansys. no. of natural frequency experimental (hz) numerical (hz) difference % 1st 65.013 60.762 6.99615 2nd 125.845 141.88 11.3018 3rd 200.246 220.82 9.31709 4th 380.856 389.94 2.32959 5th 440.218 420.77 4.622003 when the rayleigh and dunkerley methods were compared, it was discovered that the difference between them was relatively minor. for example, when using 7 nodes in the calculations for the two methods, the difference reached 3.6 percent, taking into account that the rayleigh method is lengthy in the solution because it requires 25 flexibility values, whereas the dunkerley method requires only 5 flexibility values. bear in mind that the time at once is much less than the rayleigh method. this saves effort in the calculations and is important in factories if productivity is important. 5. conclusions the rayleigh and dunkerley procedures for four states of nodes of a uniform shaft, which are used to determine the vibrations of rotating shafts, have all been thoroughly researched. through this study, the following conclusions were obtained: 1by using a number of nodes to calculate the values of the natural frequencies of rayleigh’s and dunkerley's methods, it was found that there is convergence in the results between the two methods, as the greater the number of nodes, the greater the accuracy and the more convergence in the results between the two methods. 2the most suitable application method was determined to be the dunkerley approach, which is close in results to the accurate method, with a little variation from the rayleigh method of less than 4%. 3the value of the natural frequencies reduces as the distance between the supporting bearings of the rotating shafts decreases. this result was tested and confirmed in six different positions for bearings. 4when comparing experimental and numerical data, it was discovered that the difference in findings did not surpass 20 %. this indicates that the values were converging and the results were accurate. 5the amplitude of the vibrations generated in the system increases as the spinning shaft's speed increases. it can be shown that if the rotational speed is kept low, the system becomes more stable because the critical speeds are avoided. list of symbols vw cross sectional area at node � �#� vxy cross sectional area of first element �#� vzy cross sectional area of last element �#� [ diameter (m) \ young’s modulus (pa) ], x force (^) (]* force vector matrix (^) _ gravitational acceleration � ∕ `#� aw area moment of inertia for the uniform solid beam (� ) $a& unit matrix b stiffness coefficient (n/m) $b& stiffness matrix (n/m) b. c maximum kinetic energy (j) dw length of element at node i (m) dxy length of first element (m) dzy length of last element (m) d length of shaft (m) ew ith mass of nodes (kg) exy mass of first node (kg) ezy mass of last node (kg) f, e mass (kg) $f&, $e& mass matrix (kg) g volume (�<) heij maximum potential energy (j) k weight force applied to the beam (^) l natural frequency (rad/s) m deflection of beams (m) (m* deflection of beams vector matrix (m) n flexibility influence coefficient (m/n) $n& influence coefficient matrix (m/n) o mass density (=l ∕ �<) karrar baher al-khwarizmi engineering journal, vol. 18, no. 2, p.p. 2942 (2022) 40 6. references [1] j. m. vance, f. y. zeidan, and b. g. murphy, machinery vibration and rotordynamics. john wiley & sons, 2010. [2] f. m. a. el-saeidy and f. sticher, "dynamics of a rigid rotor linear/nonlinear bearings system subject to rotating unbalance and base excitations," journal of vibration and control, vol. 16, no. 3, pp. 403-438, 2009, doi: 10.1177/1077546309103565. [3] a. h. haslam, c. w. schwingshackl, and a. i. j. rix, "a parametric study of an unbalanced jeffcott rotor supported by a rolling-element bearing," nonlinear dynamics, vol. 99, no. 4, pp. 2571-2604, 2020, doi: 10.1007/s11071-020-05470-4. [4] a. khadersab and s. shivakumar, "vibration analysis techniques for rotating machinery and its effect on bearing faults," procedia manufacturing, vol. 20, pp. 247252, 2018. 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[11] s. yang et al., "dynamic modeling and analysis of an axially moving and spinning rayleigh beam based on a time-varying element," applied mathematical modelling, vol. 95, pp. 409-434, 2021. [12] k. zhu and j. chung, "vibration and stability analysis of a simply-supported rayleigh beam with spinning and axial motions," applied mathematical modelling, vol. 66, pp. 362-382, 2019. [13] r. farshbaf zinati, m. rezaee, and s. lotfan, "nonlinear vibration and stability analysis of viscoelastic rayleigh beams axially moving on a flexible intermediate support," iranian journal of science and technology, transactions of mechanical engineering, vol. 44, no. 4, pp. 865-879, 2020. [14] m. a. aouadi and f. lakrad, "linear flexural natural frequencies and stability analysis of spinning rayleigh beams: application to clamped-clamped beams," in matec web of conferences, 2018, vol. 241: edp sciences, p. 01002. [15] m. faraji mahyari, k. faraji mahyari, and s. fardpour, "new approach to instability threshold of a simply supported rayleigh shaft," journal of solid mechanics, vol. 6, no. 2, pp. 150-157, 2014. [16] k. zhu and j. chung, "dynamic modeling and analysis of a spinning rayleigh beam under deployment," international journal of mechanical sciences, vol. 115-116, pp. 392-405, 2016, doi: 10.1016/j.ijmecsci.2016.07.029. [17] r. tamrakar and n. mittal, "experimental investigation of shaft whirl carrying 3 rotors," trends in mechanical engineering & technology, vol. 5, no. 2, pp. 17-21, 2015. karrar baher al-khwarizmi engineering journal, vol. 18, no. 2, p.p. 2942 (2022) 41 [18] c. levy, "an iterative technique based on the dunkerley method for determining the natural frequencies of vibrating systems," journal of sound and vibration, vol. 150, no. 1, pp. 111-118, 1991. [19] k. low, "a modified dunkerley formula for eigenfrequencies of beams carrying concentrated masses," international journal of mechanical sciences, vol. 42, no. 7, pp. 1287-1305, 2000. [20] s. s. rao, mechanical vibrations in si units, global edition, sixth ed. pearson, 2017. [21] j. metsebo, n. upadhyay, p. kankar, and b. n. nbendjo, "modelling of a rotor-ball bearings system using timoshenko beam and effects of rotating shaft on their dynamics," journal of mechanical science and technology, vol. 30, no. 12, pp. 53395350, 2016. [22] n. wang, d. jiang, and h. xu, "dynamic characteristics analysis of a dual-rotor system with inter-shaft bearing," proceedings of the institution of mechanical engineers, part g: journal of aerospace engineering, vol. 233, no. 3, pp. 1147-1158, 2019. [23] w. t. thomson, theory of vibration with applications. crc press, 2018. ) 2022( 2942، صفحة 2العدد، 18مجلة الخوارزمي الهندسية المجلد كرار باهر تعيب 42 ودونكرلي رايلي طريقتين باستخدام الدوارة األعمدة في االهتزازات تحليل قاسم عباس عطية** كرار باهر تعيب* عماد عبد الحسين عبد الصاحب*** *،**،***قسم هندسة الميكانيك/ الجامعة التكنولوجية/ بغداد/ العراق me.19.20@grad.uotechnology.edu.iq :البريد االلكتروني* 20044@uotechnology.edu.iq :البريد االلكتروني** 20018@uotechnology.edu.iq :البريد االلكتروني*** الخالصة االهتزاز لتحليل استخداًما األكثر التحليلية الطرق على دراسة اجراء تم. الهندسية التطبيقات في الدوارة لألعمدة االهتزازات أهمية توضيح تم الرياضية الحسابات في ألهميتهما نظراً rayleighو dunkerley لطريقتي تفصيلية دراسة إجراء تم البحث هذا في أنه حيث. الدوران عمود في منصة إنشاء تم .rayleighو dunkerley طريقة من كل في للحساب المتعددة العقد طريقة استخدام تم. الدوران نظام في االهتزازات سعة إليجاد هناك أن ثبت. المحامل بين المختلفة ولمسافات النظرية الحسابات مع النتائج ومقارنة الدوارة األعمدة في تحدث التي االهتزازات لدراسة تجريبية طريقة مقارنة تمت. المستشعرات من القادمة االهتزاز إشارة تحليل تم labview برنامج باستخدام. والنظرية التجريبية النتائج بين جيد توافق ا، بسيطًا فرًقا تحدث أنها وجد وقد. دقة األكثر الطريقة اعتبارها وتم الدقيقة، بالطريقة رايلي دنكرلي طريقة أما٪. ٠٫٠٦ حوالي إلى يصل جدً طريقة أن ووجد ،dunkerleyو rayleigh طريقتين بين مقارنة إجراء تم ثم. مقبولة وهي٪ ٤ حوالي يبلغ الدقيقة طريقة وبين بينها فالفرق dunkerley الحسابات في األنسب هي. this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 20, no. 1, march, (2024), p p. 3341 quantitative analysis of isometric ankle torque and muscle activity during dorsiflexion and plantarflexion osamah a. almasiri* ali k. buniya** hussam k. abdul-ameer*** *,**,***department of biomedical engineering / al-khwarizmi college of engineering/university of baghdad/baghdad/iraq corresponding author: *email: osama.a@kecbu.uobaghdad.edu.iq **email: alikamil85@kecbu.uobaghdad.edu.iq ***email: hussam@kecbu.uobaghdad.edu.iq (received 23 august 2023; accepted 2 october 2023; published 1 march 2024) https://doi.org/10.22153/kej.2024.10.002 abstract foot and ankle movements are essential in various activities like walking, running, and balance, where the mechanics of these movements are affected by the muscles around the ankle joint [1,2]. in this study, the correlations between isometric ankle torque and muscle activity of the tibialis anterior (ta) and gastrocnemius (gas) in the course of dorsiflexion and plantarflexion was investigated. eight healthy participants were enrolled for the study, where the ankle torque and surface electromyography (semg) of the main flexors were measured and analyzed. the results showed that ankle torque is higher in plantarflexion than dorsiflexion. in addition, the ta has greater muscle activity during dorsiflexion, while the gas presents higher activity through plantarflexion. additional investigation using power spectrum density analysis of the recorded semg was conducted and it shows the influence of fast twitching muscles on the isometric ankle torque. the outcomes of this work have the potential for developing and assessing new rehabilitation strategies. keywords: dorsiflexion, isometric ankle torque, planter-flexion, semg. 1. introduction the ankle joint represents a synovial joint facilitating a wide range of motion, encompassing dorsiflexion (upward movement of the foot) and plantarflexion (downward movement of the foot). three types of muscle contractions are identified concerning motion activity, namely concentric, eccentric, and isometric, each generating force or torque. isometric ankle torque denotes musclegenerated torque while maintaining the ankle joint in a fixed position. this torque plays a crucial role in the evaluation of ankle health, provides an indicator of the severity of ankle injuries, and assists in the monitoring of recovery progress [3,4,5,6]. the dorsiflexor muscles are a major contributor in the swing phase and regulate plantarflexion during a heel strike, while the plantarflexor muscles are essential for daily activities such as stair climbing and walking. the normal range of motion (rom) of the ankle during dorsiflexion is 10-20 degrees and 25-30 degrees during plantarflexion, contributing to inversion and eversion [7, 8, 9] ankle injuries represent the most frequent type of injury encountered during exercise and sports activities. it is hypothesized that the plantarflexors and dorsiflexors may exert a protective effect against such injuries [10]. the ankle plantarflexors may raise the risk of an anterior cruciate ligament and knee injury, while, dorsiflexion cannot bear the same capacity of a shock compared with their counterparts [10, 11]. fong et al. conducted a systematic review in 24 out of 70 sports studies, it showed that the most common site of injuries is the ankle joint [12]. in addition to sprains and fractures, there are more conditions that may lead mailto:osama.a@kecbu.uobaghdad.edu.iq mailto:alikamil85@kecbu.uobaghdad.edu.iq mailto:hussam@kecbu.uobaghdad.edu.iq https://doi.org/10.22153/kej.2024.10.002 osamah a. almasiri al-khwarizmi engineering journal, vol. 20, no. 1, p.p. 3341(2024) to ankle dysfunctions or impairments such as osteoarthritis, peripheral nervous compression, peripheral nerve trauma, peripheral neuropathy, cerebrovascular accidents, and spinal cord injuries [13]. studying ankle torque is important due to the fact that the ankle joint preserves postural stability, can manage the gait, and maintain the functioning of the lower limb. in addition, ankle joint is crucial in various physical activities like walking, running, jumping, and equilibrium control. ankle torque analysis offers awareness into the neuromuscular coordination and muscular strength of the anatomic structures surrounding the ankle joint, which contains the calf muscles, such as the gastrocnemius and soleus, as well as the muscles located on the anterior of the lower leg, like the tibialis anterior. some studies have been conducted to find the relationship between the ankle joint torque and the emg. ugbolue et al. [10] conducted an investigation to distinguish the differences in joint angles, including (rom), forces, and moments between the left and right limbs at the ankle, knee, and hip joints during dynamic dorsiflexion and plantarflexion movements in both males and females. the results revealed the effects of gender, sidedness, phases, and foot position on joint angles. in addition, this study offers data for clinicians and biomechanics working on lower limb exercise interventions and modelling efficacy standpoints [10]. different machine learning approaches can be used to assess the ankle joint torque that are useful in controlling the robotic-powered exoskeletons to assist patients with movement disorders. a combination of electromyography (emg)-driven neuromusculoskeletal (nms) model and an artificial neural network (ann) model has been used to examine the ankle joint toque in seven movement tasks, encompassing activities such as fast walking, slow walking, and self-selected speed walking, as well as isokinetic dorsi/plantar flexion at different angles [11]. in addition to the surface emg, developed nonlinear mathematical models had been used by [14] to estimate the ankle joint torque by utilizing swarm techniques to identify model parameters for dorsiflexion and plantarflexion pattern of the ankle. such a model can also help to control robotic rehabilitation for improving body movements. lateral ankle sprains (las) are a prevalent form of injury experienced by both athletes and non-athletes alike. this type of injury is responsible for a significant number of emergency room visits in different countries each year, with over one million recorded annually. therefore, understanding such an injury by studying the foot posture such as ankle inversion, internal rotation, plantarflexion, and strength is fundamental for preventing injury and finding a reliable plan for rehabilitation protocols [15,16,17]. joint flexibility can be assessed by a universal parameter which is the range of motion (rom). the relationship between joint flexibility and muscle size has been studied in several joints [18]. the utilization of non-invasive techniques, such as electromyography, poses a significant challenge due to the interference of signals originating from adjacent muscles or the stimulation artifacts induced by functional electrical stimulation (fes). therefore, zhang, q. et al. [19] suggested that a combination of an ultrasound (us) sonography with the emg signal could enhance the visualization of the muscles and lead to improved prediction accuracy of the volitional ability [18]. however, another study examined joint flexibility and related muscle action using ultrasound and magnetic resonance (mri) for better assessment [19]. the current work is driven by developing an approach to assess ankle health based on isometric contraction of two flexors, the tibialis anterior and gastrocnemius. this has been achieved using a quantitative analysis of ankle torque and semg of the ta and gas. the results of the study will help us learn more about how we can enhance the performance and function of our ankles. during the gait cycle, the ankle joint experiences dynamic loads. some studies have characterized it as a hinge joint that allows flexion and extension movements of the foot primarily in the sagittal plane [20,21], while the subtalar joint is responsible for inversion and eversion movements. in the current work, we estimated the isometric torque at the ankle joint during dorsiflexion and plantarflexion movements. a cantilever model of the foot is adopted where the lever arm is a perpendicular distance from the center of pressure on the force plate to the ankle joint center. ankle torque is then calculated by multiplying the lever arm by the force created by the center of pressure of the foot. the anatomical landmarks of the head of the fifth metatarsal bone and the lower extremity of the external malleolus are used as reference points to determine the lever arm. this model is widely used in biomechanics research due to its practicality and simplicity. however, it is important to note that for precise estimations of ankle torque, sophisticated models should be used. osamah a. almasiri al-khwarizmi engineering journal, vol. 20, no. 1, p.p. 3341(2024) such models should consider individual anatomical variations, muscle-tendon dynamics, and the intricate interactions within the foot segments. the adoption of such a complex model is outside the scope of the current study since our focus is on isometric contractions only. 2. methodology surface electromyography (semg) is a noninvasive technique used for measuring the electrical activity of the muscles. in this technique, surface electrodes are placed between the motor unit and the muscle insertion to detect the electrical signals generated by muscle contractions. these signals provide information regarding muscle activation and can be analyzed to observe muscle enrollment patterns [22,19]. we have employed semg to investigate their correlation with generated torque in the ankle during both dorsi and plantarflexion movements. our focus was on two major flexors, the ta muscle as the primary flexor responsible for ankle dorsiflexion, and the gas muscle as the primary flexor for ankle plantarflexion. by examining the semg patterns of these muscles, we have clear understanding of their activation levels and contribution to the overall ankle torque production. it is important to note that the opposite side should be tested using the same procedure to ensure consistency and determine any potential bilateral differences. the ankle dorsiflexion, which is the weaker function compared with plantarflexion, was tested first. such testing procedure enabled the participants to become familiar with performing maximum voluntary contractions before proceeding to plantarflexion testing. to measure ankle dorsiflexion torque, we firmly strapped the distal region of the foot's metatarsal to concentrate the exerted force at this specific area and stabilize the foot. participants were then instructed to pull up against the strap to flex the ankle. moreover, for ankle plantarflexion torque measurement, we placed the strap on the distal region of the thigh and passed it over the external malleolus. participants were asked to pull against the strap by extending their ankle while simultaneously pushing with the sole of their foot, attempting to lift the heel. table 1, biometric information of the eight participants. three trials were conducted, each consisting of 2-4 seconds maximal contractions, with a 30 second rest period between each trial. the maximal torque was calculated as the product of the measured force and the lever arm. the testing protocol enabled the accurate assessment of ankle torque in both dorsi and plantarflexion movements. by obtaining multiple trials and computing maximal torque values, we ensured robust and reliable data for further analysis and interpretation. the lever arms were measured for each participant, and the force was recorded by the force plate to calculate the torque around the ankle joint. on the other hand, the semg activity data were transferred to matlab for preprocessing, and to compute the amplitudes of the semg participants age height/cm weight/kg lever-arm/cm gender participant1 25 181 69.5 0.14 male participant2 26 174 101 0.149 male participant3 23 188 74 0.125 male participant4 23 169 69 0.13 male participant5 22 178 88 0.15 male participant6 23 159 59 0.1 female participant7 23 162 60.5 0.12 female participant8 23 170 72.6 0.12 male osamah a. almasiri al-khwarizmi engineering journal, vol. 20, no. 1, p.p. 3341(2024) 3. participant enrollments and experimental setup this experiment was conducted in the university of baghdad, al khwarizmi college of engineering, biomechanics lab. in this study, a total of eight healthy participants without any musculoskeletal or neurological disorders that could potentially impact lower extremity function were enrolled. all participants have provided an informed consent and their personal information was treated confidentiality. table 1 presents the characteristics of the participants in this research. to measure the reaction force of the foot, a vernia force plate was used and data acquisition was achieved using a labquest device. the participants were placed on an adjustable height stool to ensure a right angle at the hip, knee, and ankle joints. the leg was kept vertically and the foot set flat on the force plate, as illustrated in figure (1). this setup reduces the impact of segment weight, which may affect the reaction force. before recording semg, we considered several preparation measures to ensure the experiment's accuracy. first, we request participants not to bring their phones into the experimental area to prevent wireless interference since the semg sensor is based on wireless technology. second, we have prepared the equipment and ensuring the integrity of the cables for the force plate and the go-direct vernier ekg sensor, which we used to measure semg activity. third, we carefully considered the participant setup, which is an essential aspect of our procedure. this includes the target muscles that we intend to record semg activity, the ta and gas muscles. we instruct each participant to cleanse the skin area of the target muscles where the surface electrodes will be placed, ensuring it is free from hair or dead skin. we then apply a small amount of specialized conductive gel to reduce resistance between the electrodes and the skin. adhesive electrode pads were used to ensure secure attachment to the skin and consistent contact with the underlying muscles. data acquisition and analysis were carried out using a pc equipped with vernier graphical analysis and matlab software. figure (1) illustrates the experimental setup adopted in this study. to measure dorsiflexion, a non-elastic strap was positioned and secured on top of the foot at the level of the first metatarsal. we instructed the participants to perform the dorsiflexion movement which is raising the foot upward against the force plate while the semg and torque are recorded simultaneously. fig. 1. the experimental setup.the positive and negative electrodes were placed on the upper part of the dominant leg's tibialis anterior muscle for each participant. additionally, the positive and negative electrodes were positioned on the lateral side of each subject's gastrocnemius muscle a-the dorsiflexion setup. b-the plantarflexion setup. for plantarflexion measurement, the strap was placed distally on the thigh and passed directly over the external malleolus to prevent any movement during the procedure, thus ensuring osamah a. almasiri al-khwarizmi engineering journal, vol. 20, no. 1, p.p. 3341(2024) stability during the testing protocol. after this preparation, we requested the participants execute the plantarflexion movement, which moves the foot downward. 4. results and discussion the outcomes displayed in figure 2 shows the torque values for dorsiflexion and plantarflexion across the participants. notably, the torque values observed during plantarflexion are consistently higher than those during dorsiflexion for all participants. this observation aligns with previous findings [23]. participants 5, 6, and 7 exhibit less variability in their torque values compared to the other cases. this pattern could be attributed to the fact that these participants are females with a lower body mass index and relatively lower muscle density. semg signals were acquired from the participants, specifically targeting the gas and ta muscles during plantar and dorsiflexions, respectively. these muscles are known to be the primary contributors to their respective flexion movements. figure (3) illustrates the raw semg signals, which are subsequently rectified and filtered to improve analysis and interpretation. signal is proportional to the level of muscle activation. fig. 2. torques of the dorsiflexion and planter flexion for each participant. this process enhances the visibility and interpretability of the signal during analysis. filtering the semg signals allows for the selection of a specific frequency range of interest while eliminating frequencies outside that range. in the case of semg analysis, a common range of interest is typically between 20 hz and 500 hz [24][27]. generally, the ta exhibits higher muscle activity compared to the gas, except for participant 1. although this may initially seem counterintuitive, it can be explained by the significant role of the ta as the primary ankle dorsiflexor during dorsiflexion. this muscle contracts to raise the foot upwards, acting in opposition to the gas muscle, where higher muscle activity in the ta is expected during ankle dorsiflexion compared to the gas fig. 3. rectification and filtration of semg signals from tibialis muscle: participant 3 filtering the semg signals allows for the selection of a specific frequency range of interest while eliminating frequencies outside that range. in the case of semg analysis, a common range of interest is typically between 20 hz and 500 hz [24][27]. generally, the ta exhibits higher muscle activity compared to the gas, except for participant 1. although this may initially seem counterintuitive, it can be explained by the significant role of the ta as the primary ankle dorsiflexor during dorsiflexion. this muscle contracts to raise the foot upwards, acting in opposition to the gas muscle, where higher muscle activity in the ta is expected during ankle dorsiflexion compared to the gas. in plantarflexion, the gas acts as the primary ankle plantarflexor, while the ta relaxes. this will raise the muscle activity of the gas during ankle plantarflexion compared with the tibialis anterior. referring to figure 4, the obtained mean values of the rectified semg are small, except for participant 5, which may be attributed to individual and anatomical differences between the two muscles. this high activity in the ta compared to the gas osamah a. almasiri al-khwarizmi engineering journal, vol. 20, no. 1, p.p. 3341(2024) can be attributed to the ta's larger cross-sectional area, enabling it to generate higher force in comparison with the gas [24]. we acknowledge the individual variability in muscle activation levels while performing the protocol, where each participant may exhibit unique patterns of muscle activation and these differences should be taken into account during analysis and interpretation. the power spectral density (psd) of semg signals provides valuable insights into the distribution of power across different frequencies in the electrical activity of muscles. it serves as a useful tool for identifying various types of muscle contractions [25]. figure (5) shows the relation between the psd of two typical participants, 3 and 4, in which other results from participants showed the same pattern. this pattern showed that psd is higher in ta than that obtained from gas in which the largest power is noticed to be located in the frequency range > 75 hz. the ta consists predominantly of fast-twitch muscle fibers, while the gas contains predominantly slow-twitch muscle fibers. fig. 4. mean remg of ta and gas muscles (each participant) this characteristic enables the ta to generate higher force output but also makes it more susceptible to fatigue [26]. referring to [23], our results are generally in line with the findings obtained from it regarding dorsi and plantarflexions. however, our analysis of the semg activity of the primary flexors can be considered as a valuable addition to investigating the correlation between ankle torque and muscle activities. nonetheless, further investigations should be conducted to explore the impact of other flexor muscles on plantarflexion and dorsiflexion in order to gain a comprehensive understanding of muscle activation and isometric ankle torque. fig. 5. psd of the tibialis and gastrocnemius emg 5. conclusion the present study intended to explore the correlation between isometric ankle torque and the muscular activity of the tibialis anterior and gastrocnemius during plantarflexion and dorsiflexion movements. it shows that the torque values during plantarflexion are higher than those during dorsiflexion for all participants, except for three participants who showed less variability in their torque values. this variability could be referred to their lower body mass index and lower muscle density. the rectified semg show that the muscle activity of ta is higher than gas because it has a larger cross-sectional area which makes ta produce higher force. the power spectral density (psd) is greater in ta compared with gas, which can be attributed to ta's possession of a greater proportion of fast-twitch fibers. however, this particular feature enables ta to generate a higher force output but makes it more prone to fatigue. nevertheless, additional research must be undertaken to examine the influence of other flexor muscles on both plantarflexion and dorsiflexion, with the aim of acquiring a comprehensive understanding of muscle activation and isometric ankle torque. for future work and to enhance our findings, we plan to increase the number of participants and invite more female participants to 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(2024) 33-41، صفحة 1، العدد20المجلد جلة الخوارزمي الهندسيةماسامة المصيري في كل من االنقباض الظهري و الباطني والنشاط العضلي الكاحل المتجانسالتحليل الكمي لعزم دوران أسامة المصيري* علي كامل بنية** حسام كاظم عبداالمير*** جامعة بغداد /الخوارزميكلية الهندسة /قسم هندسة الطب الحياتي*،**،*** osama.a@kecbu.uobaghdad.edu.iq :البريد االلكتروني * alikamil85@kecbu.uobaghdad.edu.iq :البريد االلكتروني** hussam@kecbu.uobaghdad.edu.iq :البريد االلكتروني*** الخالصة األنشطة اليومية مثل ، أساسية لمجموعة من (توجيه القدم ألسفل)األخمصي والثني( رفع القدم ألعلى)الظهري الثني تعتبر حركات القدم والكاحل، مثل save.لكل عضلة حول مفصل الكاحل حيث تعتمد الميكانيكا الحيوية المناسبة في هذه الحركات على تنسيق عالي بين. المشي والجري والحفاظ على التوازن tالظنبوب األمامية وعضلة الساق البطنية أثناء الثني لةفي هذا البحث تم التحقق من العالقة بين عزم دوران الكاحل متساوي القياس والنشاط العضلي لعظ لتسجيل نشاط ( semg) السطحي تخدام قياس النشاط الكهربي للعضلةاشتملت الدراسة على ثمانية أشخاص أصحاء، وتم اس .الظهري والثني األخمصي عالوة على ذلك ، أظهر عضلة الظنبوب األمامية نشاًطا . النثناء الظهريأظهرت النتائج أن عزم الكاحل كان أعلى أثناء االنثناء األخمصي مقارنة با. العضالت تلقي هذه النتائج الضوء على الميكانيكا الحيوية للكاحل . عضليًا أكبر أثناء االنثناء الظهري ، بينما أظهر عضلة الساق البطنية نشاًطا أعلى أثناء الثني األخمصي عضالت هذه الدراسة تعطي تبريرا كافية إلجراء مزيد من البحث حول أدوار .لسريرية واستراتيجيات إعادة تأهيل القدمولما لها من آثار محتملة على التدخالت ا .الثني األخرى في حركات الكاحل للحصول على رؤى شاملة حول تنشيط العضالت وعزم دوران الكاحل متساوي القياس mailto:osama.a@kecbu.uobaghdad.edu.iq mailto:alikamil85@kecbu.uobaghdad.edu.iq**البريد mailto:alikamil85@kecbu.uobaghdad.edu.iq**البريد mailto:hussam@kecbu.uobaghdad.edu.iq***البريد mailto:hussam@kecbu.uobaghdad.edu.iq***البريد this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 21, no. 3, sptember, (2025), pp. 2534 efficient multitask scheduler for heterogeneous workloads with varying instruction counts 2selvakumar manickam, and *1heba m. fadhil khwarizmi college of engineering, university of baghdad, -department of information and communication, al 1 baghdad, iraq cybersecurity research centre, universiti sains malaysia, georgetown, pulau pinang, malaysia 2 heba@kecbu.uobaghdad.edu.iqcorresponding author’s email: * (received 14 february 2024; revised 7 march 2025; accepted 26 may 2025; published 1 september 2025) https://doi.org/10.22153/kej.2025.05.001 abstract multitasking systems need an efficient scheduling mechanism that minimizes the usage of resources and utilizes the system for improved output. this paper proposes an innovative scheduling framework that optimizes the distribution of resource allocation for tasks of different lengths that are run in shared computing environments. the integrated scheduler uses static and dynamic scheduling strategies for optimizing time performance and resource management. static evaluation of the analytic process entails collection of task metrics, such as the frequency of instructions and the durations of runtime. the evaluation results demonstrate the formation of the initial scheduling framework. the frameworks perform execution dynamic optimizations that reorder priorities of execution whilst considering the growth of tasks with resource conditions. the proposed scheduler yields exceptional gains in execution efficiency and throughput of the system in experimental trials with many workloads relative to conventional practices. the airplane queue management powered by the scheduler ensures establishment of an optimal system, where workload is equally distributed amongst tasks without a conflict of resources to facilitate equal, timely completion. the proposed scheduler efficiently allocates load amongst tasks and hence decreases contention of resources and leads to fair execution. the proposed scheduler combines static and dynamic scheduling approaches to maximize the utilization of resources and to improve the performance of the system. keywords: multitasking; scheduler; resource utilization; multitask learning; heterogeneous workloads. 1. introduction modern environments for computing use multitasking systems that enable computing of tasks simultaneously whilst consuming as much of the resources as possible to make the system operate more optimally. task distribution in these environments is a substantial barrier due to heterogeneous workloads that have varied instructions numbers [1]. current scheduling algorithms are also faced with the challenge of managing heterogeneous workloads effectively, which causes inefficient distribution of resources and increased execution schedules. finally, new ways are required to solve these problems with adequate effectiveness [2]. the situation with diversified conditions or workloads introduces difficulties to the use of conventional scheduling algorithms because these may have problems in addressing the complexities well. for situations when optimal resource allocation and minimum execution time may become the key success factors, creative solutions are needed [3]. this paper examines a specific issue and offers a novel approach to address ita dynamical, economical multitask scheduler. the scheduler is developed primarily to support heterogeneous workloads, which differ in instruction counts [4]. static mailto:heba@kecbu.uobaghdad.edu.iq https://doi.org/10.22153/kej.2025.05.001 https://doi.org/10.22153/kej.2025.05.001 heba m. fadhil al-khwarizmi engineering journal, vol. 21, no.3, pp. 2534 (2025) 26 scheduling is the allocation of resources that are based on usual properties of tasks without any other option attached to runtime alterations [5]. however, the accomplishments of static scheduling systems are certainly noticeable regarding some homogeneous workloads. the rigid structure of the systems is the issue when encountering the inherent diversity of heterogeneous workloads. by contrast, dynamic scheduling systems, for example, round-robin and priority-based approaches, adjust task execution depending on changing conditions. this approach, however, may not be quick enough for users to adjust to the activities that have different instruction counts, which thereby results either in unproductive use of resources or resource conflict [6[ , ]7] . task scheduling uses artificial intelligence algorithms based on neural networks and reinforcement learning models, but it demands large training datasets and produces high computational requirements. static analysis forms part of the proposed scheduling framework that jointly works with dynamic prioritization. by implementing this approach, organizations can avoid intensive training requirements yet maintain dynamic workload adjustment abilities. this scheduler operates with reduced computational loads due to its minimalist design and thus meets temporal requirements within resource-limited systems [8], [9]. the primary aims of this paper are twofold: firstly, to offer a scheduler that supports managing the difficulties of multiprocessing platforms with a variance of executed instructions and secondly, prove exclusively the effectiveness of the proposed scheduler through in-depth experimental evaluations. through the attainment of these goals, value is aimed to be added to multitask scheduling methods, specifically with respect to performance improvement of systems in a variety of computing scenarios. the focus of this paper is to propose substantial directions and solutions that could remarkably enhance and optimize the performance of computing systems through the deep investigation of the problems surrounding multitask scheduling and to present a new method of tackling such problems . the present paper is organized in the following manner: the existing state of multitask scheduling in various situations is described in section 2. the schematics from the design to the architecture of the proposed scheduler are presented in section 3. the details of the static analysis phase and dynamic adaption procedures are also included. a thorough evaluation and design of the experiment performed in this study is discussed in section 4. the outcomes of the experiments as well as the discussions that follow are presented to elaborate the findings in section 5. all the constraints in the proposed strategy, areas to be further explored and areas for future research are covered in section 6. the contributions of this work are summarized in section 7. the importance of designing an efficient multitask scheduling in heterogeneous computing systems is stressed. 2. related work computing systems’ multitasking scheduling method has become a notable field of study because of its direct effect on how resources are allocated and how system performance is optimized. different approaches for scheduling tasks exist today as static and dynamic algorithms with separate strengths and matching performance constraints . the static scheduling techniques described by rekha and dakshayini (2019) used predefined task information for resource distribution [10]. through a unique genetic algorithm method, cloud resource utilization was optimized, yet the approach demonstrated limitations when handling dynamic workloads featuring heterogeneous characteristics with varying instruction requirements. liu et al. (2021) demonstrated a dynamic scheduling system that employed neural networks as an instrument to support multitasking workloads in maritime environments. these approaches delivered high accuracy results within certain operational environments, yet their extensive training dataset requirements along with substantial processing demands challenged the real-time system implementation [11] . hybrid scheduling algorithms incorporate static and dynamic methodologies to address system challenges that have recently risen. sanh et al. (2019) developed a hierarchical multitask system that prioritizes tasks through workload-dependent mechanisms. however, this method was designed for semantic processing and applied only to homogeneous environments [12]. task consistency frameworks developed by zamir et al. (2020) showed enhanced computational efficiency but demanded lengthy customization work for specific application domains [13]. conventionally, each task is mined on a minibatch basis intermittently with the training order either uniform or secondary to the size of the database the task is associated with [14]. nevertheless, such simplistic approaches can bring heba m. fadhil al-khwarizmi engineering journal, vol. 21, no.3, pp. 2534 (2025) 27 on extra computations; through redundancy, tasks and/or some tasks may be just prerequisites for others to be learnt [15]. moreover, mismatches amongst the tasks may damage an appropriate training by causing mismatches between backpropagated gradients [16]. therefore, methods to train tasks and samples in a particular sequence have been developed by researchers and are known as ‘mtl scheduling’. mtl scheduling aims to improve the training procedure by smartly arranging the order of tasks’ and samples’ processing. this approach can reduce redundant computations, imbalance issues and undesired calculations, which increases the performance of the multitask learning [17]. much effort has been made about workloads with mixed characteristics in the form of instruction counts with relation to specialized scheduling techniques. methods proposed by many studies have utilized instruction counts as indicators for task prioritization and resource allocation. however, these projects are usually hallmarked by the fallibility of generalizing the combined application of static and dynamic strategies that could further achieve a synthesized validation of both these types and hence neglect the potential benefits of a combined integration, which results in a reduced performance score [18]. the main purpose of this paper is to address this existing gap in the current research subject by offering a multitask scheduling approach that combines all the possible studies on the subject from different authors. the proposed scheduler combines static analytic techniques to obtain the details of task numbers of the instructions and dynamic adaptations to optimize resource use. one of the aims of this work is to design an integratorbased scheduler that can unite several methodologies to govern a variety of workloads. this scheduler seeks to remove the hindrances involved in such workloads whilst leveraging on the advantages offered by static and dynamic approaches . in summary, the developed literature helped indicate different kinds of multitask scheduling algorithms. nevertheless, a glaring deficiency is noted in the literature on the management of workloads containing heterogeneous instructions with varying numbers. this paper aims to be a step forward in the field by proposing a new scheduler that meets the idea of static and dynamic scheduling integration. this integration aims to provide an algorithm that improves multitask performance within various computing contexts. 3. system architecture and design the detailed design of the proposed efficient multitask scheduler is constructed to work efficiently against challenges presented by heterogeneous workloads of diversely varying instruction counts. in this section, the components of the architecture are delineated, the functions of the components are given insight into, and the workflow of the scheduler is presented, as explained in figure 1 and algorithm 1. the fluid interaction of the used scheduling technique of the static and dynamic kind that form the basis of the scheduler’s design is also emphasized in this section. the scheduler consists of three key components: 1. task information analyzer (tia): the tia is the first stage of the scheduler work. a static analysis of a multitasking environment is performed, and information about every task is collected such as the task’s instruction count, estimated execution time and resource requirements. these data form the basis for further scheduling. 2. static scheduler (ss): leveraging the findings from the tia, the ss develops an initial scheduling plan during the system boot up. this plan factors in the varying instruction counts of tasks and allocates resources to reduce contention and to improve execution time. the ss creates a balanced allocation that optimizes resource consumption and prevents the unfairness of opposite tasks. 3. dynamic adaptation manager (dam): the dam operates in runtime and dynamically modifies the priorities of tasks and resource allocations during task execution according to the progress of tasks and the status of resources. the dam adopts an intelligent task priority algorithm that considers task instruction numbers and historical execution information. dynamic adaptation guarantees reasonably good resource usage and allows the scheduler to react promptly to changes in workload features. heba m. fadhil al-khwarizmi engineering journal, vol. 21, no.3, pp. 2534 (2025) 28 fig. 1. proposed system architecture flowchart the scheduler task graph management combines the static analysis part and dynamic adaptation during the operation and thus provides an integrative, iterative and proactive multitask scheduling mechanism. 1. static analysis phase: ▪ the tia collects task information such as the number of instructions and the duration of execution through the profiling approach or user-supplied data. ▪ with this information, the ss develops an initial scheduling scheme to assign tasks, whilst the executions and the resource usage are minimal. 2. dynamic adaptation during runtime: if a highquality product at a competitive price is desired, the instructions should be performed now if the order is needed to be delivered in a timely fashion. ▪ when the tasks start their execution, the dam continuously monitors their progress and the resources’ availability. ▪ based on the data updated in real time, the dam adjusts dynamic priorities in task, where the tasks with higher instruction counts receive proper resource allocation to avoid stalls. ▪ an intelligent prioritization algorithm of the scheduler considers the remaining instruction counts and the historical execution patterns, and thus makes informed decisions. the interplay of the static analysis stage and the runtime dynamic adaptation is the keystone for the scheduler. the initial schedule provided by the static scheduler serves as a solid baseline, and the dynamic adaptation mechanism ensures ongoing responsiveness to workload dynamics. this integration enables the scheduler to draw on the best of both methods and improves resource utilization and runtime in heterogenous multitasking. algorithm 1 : dynamic scheduling and adaptive prioritization algorithm initialization: initialize priority_queue // priority queue to hold tasks initialize execution_history // data structure for task execution history while system is running: update tasks: for each task t in system do: t.progress += t.execution // update task progress t.remaining_instructions -= t.execution // update remaining instruction count end update priorities: for each task t in system do: t.priority = calculate_priority(t) // calculate task priority based on instruction count and history priority_queue.enqueue(t, t.priority) // enqueue task based on priority end allocate resources: for each available resource r do : start initialize a priority queue initialize a data structure to store task execution history update t's progress based on its execution update t's remaining instruction count calculate t's priority enqueue t into the priority queue dequeue a task t from the priority queue allocate resource r to task t execute tasks that have been allocated resources update execution history for executed tasks if t's execution time exceeds a threshold: decrease t's priority periodically adjust the priority thresholds end for each task t in the system: for each task t in the system: for each available resource r: for each task t in the system: heba m. fadhil al-khwarizmi engineering journal, vol. 21, no.3, pp. 2534 (2025) 29 task_to_execute = priority_queue.dequeue() // dequeue highest priority task allocate_resource(r, task_to_execute) // allocate resource to task for execution end execute tasks: execute_tasks() // execute tasks that have been allocated resources update_execution_history() // update execution history for executed tasks end adjust prriorities: for each task t in system do: if t.execution_time > threshold or resource_contention_issue(t) then : decrease_priority(t) // decrease priority to mitigate contention and starvation end end update adaptive thresholds: update_adaptive_thresholds() // periodically update priority thresholds end the designed multitask scheduler’s architecture and design are considerately assembled to undertake the intricacies associated with managing diverse workloads with numerous instructions. merging static analysis and dynamic adaptation techniques endows the scheduler the power to deliver resource allocations efficiently, minimizes execution times and promotes improved overall system performance. the subsequent sections introduce the intricate implementation of these architectural components and highlight the outcome on their overall effect. 1. static analysis phase: the static analysis phase of the proposed efficient multitask scheduler is a pivotal precursor to a sound scheduling within heterogeneous multitasking environments exhibiting variable instruction counts. this section covers the whole process of collecting task information and creating an initial scheduling plan and the aspects to be balanced to obtain the right resource allocation. 2. gathering task information: the static analysis phase begins with the collection of the appropriate information regarding each task in a multitasking workload. the information provided is the instruction count of the task and its estimated runtime. these metrics are critical in engaging the necessary estimation of the computational requirements of each task upon which later scheduling decisions hinge. instruction count measures the complexity of a task’s computation, whereas estimated execution time sheds light on the overall processing needs. based on the collected tasks’ information, the scheduler generates the initial scheduling plan at the system’s initiation. the scheme presents the division of tasks to available resources to minimize execution time and to prevent resource conflict. the initial schedule originally integrates heuristics and optimization methods. tasks with fewer instruction counts are firstly assigned available resources to execute these tasks quickly; however, tasks with higher instruction counts are strategically assigned to resources to prevent these tasks from creating a bottleneck. in initial planning, the right steps are taken to optimize the distribution of resources with the following considerations: 1. the scheduler balances the computational load amongst the available resources. the instructions take varying numbers spread evenly to prevent either underutilizing or overutilizing resources, which leads to efficient resource utilization. 2. the initial plan reflects the available resources and their capabilities. resource constraints such as memory limitations or cpu usage are included to prevent task allocation that exceeds resource capacities. 3. dependencies between tasks are introduced to avoid conflicts and to force the scheduling to fulfil the dependent tasks’ requirements. 4. tasks initially planned with critical instruction counts are offered higher priority because they need to receive enough resources to fast track their execution. by combining the above aspects, the scheduler’s static analysis phase builds a good groundwork for efficient multitask scheduling. the initial scheduling plan deduced from a thorough comprehension of task instruction counts and estimated execution times aims to maximize resource utilization, shorten execution time and balance execution amongst heterogeneous tasks. the static analysis phase supports the foundation for multitask scheduling. the integrated reception of job data along with the unbiased development of first scheduler plans and appropriately foreseeing the distribution of the resources enables the scheduler to overcome the problem of diversity of heterogeneous workloads with varying instruction counts. the upcoming parts concentrate on the dynamic adjustment approaches based on the runtime playoff to make the method of the proposed scheduler even more efficient. this algorithm combines real-time tracking of task heba m. fadhil al-khwarizmi engineering journal, vol. 21, no.3, pp. 2534 (2025) 30 progress, dynamic prioritization based on remaining instruction counts and execution history, and mechanisms for resource allocation and contention mitigation. efficient multitask scheduling is ensured in the face of varying instruction counts, which promotes optimal resource utilization and execution time minimization. 4. experimental evaluation to assess the experimental part, a variety of input configurations was used for estimating the quality of the proposed task scheduler. the inputs were formulated with the help of tasks (x); dependency matrix representing the task dependencies; number of processors (x + 1); or million instructions per second for each processor (x + 2). the metrics of concern, namely, execution time, processor utilization and task completion time, were considered to measure the level of scheduling efficiency of the scheduler. these test scenarios were distinguished by the size of the tasks, relationships of the tasks between one another and the type of the processors used for the tests. for instance, scenario 1 had a small input that had 5 tasks and 2 processors, whereas scenario 3 had a larger input that had 12 tasks and 4 processors. the outcomes of the scheduler’s flexibility and scalability disclosed the strengths and weaknesses. the results provide a full-fledged vision of the workings of the task scheduler under the various circumstances and outline the optimizations and improvements to be implemented in future works. 5. results and discussion the proposed multitask scheduler was evaluated under three distinct experimental scenarios to assess its performance across varying workloads and resource configurations: the experimental conditions assessed tasks with five processes running on 2 processors for small workloads, 12 tasks distributed across 4 processors for medium workloads and 20 tasks spread across 6 processors for large workloads. the experimental setups evaluated the proposed scheduler with uniform task populations between 5 and 20 along with differing cpu capacities in simulated realworld conditions. process execution times, cpu usage data and task distribution fairness became the key measurement points throughout the testing. in all the experimental scenarios, the proposed scheduler demonstrated superior execution time capabilities than traditional scheduling techniques, particularly round-robin and priority-based approaches, and led to performance improvements of 15%, 23% and 28% for smallto large-dimension workloads. the algorithm showed optimally distributed processor usage during the large-scale test that delivered 85% processor utilization compared with round-robin’s 70% that produced underused processors. higher fairness in task completion emerged from the scheduler because resources were redistributed towards tasks with higher instruction counts. this approach eliminated delays and congestions. the results in figure 2 and an execution time reduction from 10.5 s to 8.1 s demonstrated the medium-scale scenario benefits achieved by using the proposed scheduler. the scheduler demonstrated improved workload distribution capabilities combined with reduced idle periods and enhanced scalability across various workload dimensions to improve execution times and resource usage performance compared with established methods. the distribution task schedule across four processors (p1, p2, p3 and p4) is presented in figure 2. analyses of the execution data reveal effective processor task distribution with low periods of inactive processing time. processor p1 operates under heavy processing requirements through continuous task execution showing occasional timing overlap between tasks. the workload in p4 shows through its decreased overall task duration. the scheduler exhibits excellent performance because tasks are distributed fairly amongst processing units by using target instruction counts and available resources. the distribution system assigns workloads between processing units to prevent any unit from receiving an excessive workload. the task structures of p2 and p3 display a regular pattern where distinct instructions are distributed to separate processors to prevent resource conflicts. the observed sequential execution on p2 and p3 points to scheduling-based dependency management within the system. the scheduler transforms resource distribution dynamically, which becomes evident through p1’s overlapping session times and p3’s synchronized execution sequence with p4. heba m. fadhil al-khwarizmi engineering journal, vol. 21, no.3, pp. 2534 (2025) 31 fig. 2. scheduling results of 10 task configuration a distribution pattern like the first is observed in the second set of results with an additional processor (processor 3). the algorithm allocates jobs 0, 1, 6, 2, 7 and 10 to processor 0; jobs 3, 4 and 8 to processor 1; jobs 5 and 9 to processor 2 and job 11 to processor 3. this approach is scalable because it allows more tasks and processors to be taken whilst the scheduling remains efficient, as illustrated in figure 3. fig. 3. scheduling results of 12 task configurations in the third set of results, a more varied task allocation across processors is seen. processors 0, 1 and 2 execute jobs 0, 9, 1, 2, 12 and 3; jobs 6, 10, 4 and 5; and jobs 7, 13 and 11, respectively. task 8 is assigned to processor 3 as well. the algorithm also exhibits varying task interdependencies and processor capacity, as shown in figure 4. fig. 4. scheduling results of 14 task configuration other variations in tasking approaches are found in further result sets. processors operate at their maximum capabilities assuming the constraints and processor capabilities remain constant. the algorithm is flexible with allocating tasks so that the workload across resources is distributed optimally, which results in minimum runtime and enhanced system performance, as shown in figure 5. fig. 5. scheduling results of 16 task configurations consequently, the results substantiate scheduling policy efficiency in handling multitask running across heterogeneous computational environments. considering task dependencies and processor capabilities, the algorithm allows rational resource use and minimizes execution time. however, more fine-grained analytical studies and replicable experiments are needed to measure the algorithm’s performance under various workload conditions and to compare its scaling and robustness under complex real-world systems. heba m. fadhil al-khwarizmi engineering journal, vol. 21, no.3, pp. 2534 (2025) 32 6. limitations and future work although the proposed scheduling algorithm shows positive outcomes, some disadvantages that should be taken care of require additional research. the algorithm’s performance can diverge from expectations due to the complexity of the task dependencies and initially the heterogeneity of the processor capabilities in the beginning. to keep the algorithm running in a feasible time, increasing the number of processors and operations beyond need is not advisable. thus, the scheduling would be nonoptimal, and the runtime would become longer. to surmount this defect, more sophisticated scheduling algorithms that can handle complex task dependencies and diverse computing environments are needed. in addition, the current algorithm may not completely handle dynamic changes of workload and resource allocation during runtime. future work could improve algorithm responsiveness to dynamic changes in task demand and processor capacity. this approach will involve the amalgamation of live monitoring and feedback systems that will enable dynamic adjustments of task priorities and resource allocations in response to time-changing circumstances. the approach also relies on the predefined thresholds for priority adjustment and adaptive threshold updates, which may impose difficulty in overcoming contention and starvation. future studies could employ sophisticated methods, including processor learning–based algorithms, to learn automatically and to adapt priority thresholds according to the past execution information and system dynamics. thus, the algorithm evaluation spotlights scheduling performance indicators such as execution time and resource usage. in future studies, other criteria beyond the discussed ones such as energy efficiency and cost effectiveness, particularly, the case of using algorithms in realworld applications, cannot be ignored. 7. conclusion the proposed scheduling algorithm exhibits good performance despite limitations and opportunities for future research. the presented task scheduling algorithm displays great results in effectively spreading tasks in heterogeneous computing environments. whilst using dependency constraints and processor capabilities, the algorithm finds the configuration that preserves the best utilization and the least execution time. the results validate the satisfactory performance of the algorithm for task allocation. for instance, the results from the first set show distribution of tasks amongst three processors with processor 0 running tasks 0, 1, 2, 6 and 7, whilst processor 1 runs tasks 3, 4 and 8, and processor 2 executes tasks 5 and 9. consequently, subsequent outcomes reflect varying strategy of task allocation showcasing the algorithm's adaptability to different workload and resource availability situations. further studies should be devoted towards resolving these limitations and improving the algorithm’s functionalities. more advanced scheduling algorithms capable of dealing with a large scale of task dependencies and analysing priorities dynamically in response to variations of workload-based conditions must be found. the scope of the evaluation criteria should also be widened to include factors such as energy efficiency, economic feasibility and fault tolerance to realize a more holistic assessment of the algorithm’s practical utility in the real world. the task scheduling algorithm discussed can improve the performance of task execution in heterogeneous computing environments, although some areas need improvements. the research and further development will result in the creation of sophisticated scheduling solutions that can adapt to the constantly changing needs of modern computing systems. references [1] m. a. alworafi, a. dhari, a. a. al-hashmi, suresha, and a. b. darem, “cost-aware task scheduling in cloud computing environment,” international journal of computer network and information security, vol. 9, no. 5, 2017, doi: 10.5815/ijcnis.2017.05.07 . 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[5] v, karunakaran. “a stochastic development of cloud computing based task scheduling algorithm.” journal of soft computing paradigm 2019, no. 1 (september 22, 2019): 41–48. https://doi.org/10.36548/jscp.2019.1.005 . [6] p. m. rekha and m. dakshayini, “efficient task allocation approach using genetic algorithm for cloud environment,” cluster comput, vol. 22, no. 4, 2019, doi: 10.1007/s10586-019-02909-1 . [7] e. silva and p. gabriel, “genetic algorithms and multiprocessor task scheduling: a systematic literature review,” sociedade brasileira de computacao sb, mar. 2020, pp. 250–261. doi: 10.5753/eniac.2019.9288 . [8] s. javanmardi, g. sakellari, m. shojafar, a. caruso, why it does not work? metaheuristic task allocation approaches in fog-enabled internet of drones. simulation modelling practice and theory. 133 (2024), doi:10.1016/j.simpat.2024.102913 . [9] heba m. fadhil, “optimizing task scheduling and resource allocation in computing environments using metaheuristic methods,” fusion: practice and applications, vol. 15, no. 1, pp. 157–179, 2024, doi: 10.54216/fpa.150113 . [10] s. ruder, “an overview of multi-task learning for deep learning,” sebastian ruder. 2017 . [11] z. liu, m. waqas, j. yang, a. rashid, z. han, a multi-task cnn for maritime target detection. ieee signal processing letters. 28, 434–438 2021. [12] a. zamir, a. sax, w. shen, l. guibas, j. malik, and s. savarese, “taskonomy: disentangling task transfer learning,” in ijcai international joint conference on artificial intelligence, 2019. doi: 10.24963/ijcai.2019/871 . [13] v. sanh, t. wolf, and s. ruder, “a hierarchical multi-task approach for learning embeddings from semantic tasks,” in 33rd aaai conference on artificial intelligence, aaai 2019, 31st innovative applications of artificial intelligence conference, iaai 2019 and the 9th aaai symposium on educational advances in artificial intelligence, eaai 2019, 2019. doi: 10.1609/aaai.v33i01.3301694. [14] p. e. chavarrias, a. bulpitt, v. subramanian, and s. ali, “multi-task learning with crosstask consistency for improved depth estimation in colonoscopy,” medical image analysis, vol. 99, p. 103379, jan. 2025, doi: 10.1016/j.media.2024.10337. [15] e. kiperwasser and m. ballesteros, “scheduled multi-task learning: from syntax to translation,” trans assoc comput linguist, vol. 6, 2018, doi: 10.1162/tacl_a_00017 . [16] z. chen, v. badrinarayanan, c. y. lee, and a. rabinovich, “gradnorm: gradient normalization for adaptive loss balancing in deep multitask networks,” in 35th international conference on processor learning, icml 2018, 2018. [17] p. liu, x. qiu, and x. huang, “adversarial multi-task learning for text classification,” in acl 2017 55th annual meeting of the association for computational linguistics, proceedings of the conference (long papers), 2017. doi: 10.18653/v1/p17-1001. [18] s. vandenhende, s. georgoulis, w. van gansbeke, m. proesmans, d. dai, and l. van gool, “multi-task learning for dense prediction tasks: a survey,” ieee transactions on pattern analysis and processor intelligence, vol. 44, no. 7. 2022. doi: 10.1109/tpami.2021.3054719 . (2025) 34-25، صفحة 3، العدد21مجلة الخوارزمي الهندسية المجلد هبة محمد فاضل 34 برنامج جدولة متعدد المهام فعال ألحمال العمل غير المتجانسة مع أعداد تعليمات مختلفة 2سيلفاكومار مانيكام، *1فاضل حمدهبة م المعلومات واالتصاالت، كلية الهندسة الخوارزمي، جامعة بغداد، بغداد، العراق هندسة قسم 1 ، جورج تاون، بوالو بينانغ، ماليزيا جامعة العلوم الماليزية ي، مركز أبحاث األمن السيبران 2 heba@kecbu.uobaghdad.edu.iq*البريد االلكتروني: المستخلص يهدف . وتحقق أداًء متفوقًا للنظام. يقدم البحث إطاًرا مبتكًرا للجدولة ، على تحسين استخدام المواردتتطلب أنظمة المهام المتعددة طرق جدولة فعّالة تعمل ليب الجدولة إلى تحسين تخصيص الموارد الموزعة للمهام ذات األطوال المختلفة التي تعمل في بيئات حوسبة مشتركة. يقوم المجدول المتكامل بتطبيق أسا لمهام مثل تكرار التعليمات وتقدير مدة الثابتة والديناميكية لتحقيق كل من تحسين األداء الزمني وإدارة الموارد. تبدأ عملية التحليل بتقييم ثابت لجمع مقاييس ا يات التنفيذ وفقًا لتقدم أولو وقت التشغيل. تؤدي نتائج التقييم إلى تطوير إطار جدولة أولي. يقوم اإلطار بتنفيذ تحسينات ديناميكية أثناء وقت التشغيل تعيد ترتيب أن المجدول المقترح يحقق تحسينات ملحوظة في كفاءة التنفيذ وإنتاجية النظام مقارنة منها متعددة العمل الالمهام وظروف الموارد. أظهرت التجارب أعباء ن المهام مع تجنب باإلجراءات القياسية. يساهم المجدول في إدارة طوابير الطائرات بشكٍل فعال، حيث يخلق نظاًما محسنًا يضمن توزيعًا متساويًا للعبء بي لضمان إتمام المهام بشكل عادل وفي الوقت المناسب. يوزع المجدول المقترح األحمال بشكل جيد عبر المهام، مما يقلل من التنافس على ؛ تضارب الموارد .هجيات الجدولة الثابتة والديناميكية لتعظيم استخدام الموارد وتحسين أداء النظامالموارد ويؤدي إلى تنفيذ عادل. في المجمل، يجمع المجدول المقترح بين من mailto:heba@kecbu.uobaghdad.edu.iq this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 20, no. 3, september (2024), pp. 5970 enhancing risk management: leveraging the likelihood/severity matrix for effective risk assessment and mitigation in the electrical and electronic sector alaa salahuddin araibi*, huda h. dalef**, hiba k. hussein***, mohamad shaiful ashrul ishak**** and muhammad roslan rahim***** *,**,*** department of automated manufacturing engineering, al-khwarizmi college of engineering, university of baghdad, baghdad, iraq **** faculty of mechanical engineering and technology, universiti malaysia perlis, kampus alam pauh putra, 02600 arau, perlis, malaysia ***** faculty of mechanical engineering, universiti teknologi malaysia, 81310 utm johor bahru, johor, malaysia * email: alaasalahudien@gmail.com (corresponding author) ** email: huda@kecbu.uobaghdad.edu.iq *** email: hibakh@kecbu.uobaghdad.edu.iq **** email: mshaiful@unimap.edu.my ***** email: roslan_zultech82@yahoo.com (received 10 december 2023; revised 2 may 2024; accepted 16 june 2024; published 1 september 2024) https://doi.org/10.22153/kej.2024.07.003 abstract this paper presents the basic concept of risk and reviews commonly applied tools and techniques for risk assessment. generally, risk assessment is a completely experiential decision-making process based on experience and knowledge of risk assistants. this paper emphasises one quantitative/qualitative technique, namely the likelihood/severity matrix approach, which aims to direct the organisation’s attention towards risks that have the highest potential to have a negative effect. this paper’s main contribution lies in introducing a proposed model that utilises the likelihood/severity matrix approach to categorise risks into ‘regions’ and subsequently rank them. this process supports risk managers in making informed decisions to reduce risks effectively. a likelihood/severity matrix was examined through a case study belonging to the electrical and electronic sector to find the critical risks that hinder the assembly line of personal computers. results showed that the ‘breaking parts during assembly’, ‘shocking the components from static electricity discharge’ and ‘using wrong compatible parts’ risks had the maximum risk score, with values of 10–15 as the most critical risks. these results can influence decision makers in developing actions to mitigate these highlighted risks. keywords: likelihood/severity matrix approach; risk assessment; risk log 1. introduction nowadays, in a business world full of instabilities, industry operations face unexpected challenges. the latest events, such as the wuhan coronavirus outbreak, have affected many operations worldwide, leading to increased uncontrollable risks. for this, a quick response with the use of data and establishing a strong system is needed [1]. although the idea of risk is not new with the growth of risk management (rm), some important methods still need to be appraised, such as the likelihood/severity matrix. the likelihood/severity matrix is a definitive technique that can be supportive and perceptive to approve needed decisions as it presents risk data in a brief, graphical and mathematical manner. a likelihood/severity matrix is often colour-coded and utilises qualitative, quantitative and semiquantitative methods to rank various types of risk mailto:alaasalahudien@gmail.com mailto:mshaiful@unimap.edu.my mailto:roslan_zultech82@yahoo.com https://doi.org/10.22153/kej.2024.07.003 alaa salahuddin araibi al-khwarizmi engineering journal, vol. 20, no. 3, p.p. 5970 (2024) 60 based on their levels, enabling the prioritisation of risk mitigation starting from the highest ranks [2]. the purpose of any risk assessment tool/technique is to confirm that the decision-making process is strong, depending on the best knowledge of stakeholders [3,4]. a likelihood/severity matrix manages risks through a matrix approach, which includes identifying the type of damage and the probability of occurrence for each risk. by plotting these values on a matrix, stakeholders and top management can gain a visual representation of the risks, prioritise resource allocation for rm, disclose information about external risks and distribute responsibilities amongst managers [5]. this technique ensures transparency in the analysis process and allows for adaptation to evolving threats, vulnerabilities and assets in the digital economy [6]. this paper delves into the utilisation of the likelihood/severity matrix approach to enhance rm in the electrical and electronic sectors. it introduces a model that classifies risks based on their likelihood and severity, aiding decision makers in prioritising and managing critical risks. in addition, the article delves into the fundamental concepts of risk, engineering rm (erm), a range of risk assessment tools and techniques and a comprehensive risk assessment model. ultimately, this model empowers risk managers to make well-informed decisions by targeting high-impact risks for effective risk reduction. 2. literature review 2.1. concept of risk the terms likelihood, risk and uncertainty are typically associated with anticipating future events or unknown severities of past events. the main aim of these forecasts is to assist in the decisionmaking process [7]. uncertainty refers to the absence of specific knowledge that is deemed essential for making informed decisions [8]. this interconnection between uncertainty and risk is fundamental in the realm of rm. rm emerges as a crucial method for businesses to navigate uncertainties and ensure their survival while striving to achieve their objectives. risk itself can be defined as the amalgamation of the likelihood and severity of an undesirable event, forming the core of rm science. [9]. a risk has three components: the event, the likelihood of the event and the severity of the event. the two types of severity from uncertain states are risks and opportunities [10,11]. rm strives to understand and control risks that may disturb a project while increasing the chances of positive outcomes [12]. after defining the notion of risk, the combination of risk likelihood and risk severity is called risk score [13,14]. risk score = (likelihood) × (severity) …(1) likelihood refers to how often an event occurs and is measured in terms of the number of events per time unit given in percentage. it is described by a discrete distribution. severity depends on the significance of the occurrences of the events, and it is described by a continuous distribution (e.g. normal distribution, gamma distribution, exponential distribution, and beta distribution) [15]. 2.2. erm rm is the skill and knowledge of finding, analysing and reporting on risks throughout the life of a project and in the finest awareness of meeting project goals (schwalbe, 2015). erm includes the comprehensive management of an engineering system, which is varied and continuous, with the target of guaranteeing the functionality and reliability of the system. as the engineering system will possibly be at risk due to operational and technical factors, an application of the erm process can decrease the occurrences of such risks [9]. figure 1 shows the rm processes as defined below (rose & hillson, 2004). these processes are applied in an endless cycle of continuously discovering and removing risks. alaa salahuddin araibi al-khwarizmi engineering journal, vol. 20, no. 3, p.p. 5970 (2024) 61 fig. 1. rm processes [16]. 2.3. risk assessment tools and techniques about 30 risk assessment tools and techniques can be classified in various ways to define and assess risks [17]. risk assessment approaches help spot and define all risks in the hope of making a clear decision on how to use resources strategically and gainfully to observe and decrease the likelihood and severity of the supposedly undesirable events [18]. risk assessment methods can be classified into quantitative and qualitative approaches. the quantitative risk assessment approach is a way of quantifying the likelihood and the severity of risks in a project through numerical estimates of its cost and time objectives. conversely, the qualitative risk assessment approach is the identification, assessment and reduction of prioritised lists of risks on the basis of the insight of the likelihood and severity by stakeholders [19,18]. table 1 shows the most common risk assessment tools and techniques applied by various references that have been classified into quantitative and qualitative approaches. definition • identify and document opportunities to analyze engineering systems and indicate the risk analysis process to be performed. risk identification • identifying and documenting risks that could potentially impact the system's objectives is a crucial step in the risk assessment process. risk assessment • the utilization of qualitative and/or quantitative risk assessment tools and techniques is geared towards identifying and managing the magnitude of each risk, along with assessing its likelihood of occurrence and impact. risk response planning • use of appropriate schemes and plans to reduce the impact of discovered risks. risk monitoring, control and review • continual checking, supervising, critically observing or determining the status in order to identify change from the performance level required or expected • implementation of decided actions and checking their efficiency, reporting to decision makers, entry in risk registers. alaa salahuddin araibi al-khwarizmi engineering journal, vol. 20, no. 3, p.p. 5970 (2024) 62 table 1 risk assessment tools and techniques. ref. tools/techniques methodology classification result and conclusion c h ec k li st s s tr u c tu r e d i n te r v ie w a n d b r a in st o r m in g r o o t c a u se a n a ly si s (s in g le l o ss a n a ly si s) d e lp h i t e c h n iq u e f a u lt t r e e a n a ly si s c a u se -a n d -e ff e c t a n a ly si s f a il u r e m o d e a n d e ff e c t a n a ly si s r is k r e g is te r s w o t a n a ly si s m o n te c a r lo s im u la ti o n q u al it at iv e q u an ti ta ti ve se m iq u an ti ta ti ve [39] √ a fuzzy analytic hierarchy route examines the stages of the product lifecycle. √ a new methodology for risk scoring of the production stages of wind turbines [33] √ the causes and effects of accidents are analysed using fcm, which depends on three targets and effects of risk factors. √ roof falls, gas poisoning and debris with destruction impose high risks on the system. on the contrary, the lowest risk amongst all accidents are collisions and crashes. [25] √ root cause analysis (single loss analysis) √ the root cause of a reoccurring problem is identified and eliminated depending on previously unknown social and administrative causes. [24] √ the initial version of the checklist, composed of 29 items in 9 units, was analysed and assessed by 13 experts. √ the application of the specification will permit the effective risk valuation of the hygienic and sanitary observations and conditions in food trucks. [24] √ audit firms are required by sasaltered types to use brainstorming sessions for evaluating risk factors. √ information retrieval offered by interactive decision provision and the risk in an audit brainstorming session [26] √ analysis: problem’s frequency, notice’s time and different error characteristics (cataloguing of the item, where the fault happened, times that occur during the day and week and result) √ quality improvement activities have been briefed: structural changes, changes to policies and practices, changes in individual responsibilities and improving workplace culture to counteract underreporting of errors [34] √ a method of performing detection actions for a problem and corrective activities for negative effects √ presented a literature review about the various methods and applications of fmea that have been developed until 2018 [31] √ focused on how assessors can handle uncertainty based on available evidence √ review of previous works, focusing on uncertainty handling in fault tree analysis (fta) depending on risk assessment [42] √ practised questionnaire survey with the ahp used to the impact and probability scores of risks, and the sensitivity analysis of volatile risk events √ developed risk assessment framework applied to a real mining project to demonstrate its application in the mining industry [29] √ analysed the occurrence of top events even in the absence of historic probability data using the ffta framework √ expected helpful results to safety specialists while making decisions related to rm of oil and gas pipeline [32] √ analysed the cause and effect to systematically describe sources of variability with four key in vitro nanobioassays √ used four approaches to support the development of a wide variety of nanobioassays [19] √ analysis of modern safety extortions in wireless sensor networks, vehicular ad hoc networks and internet of things/industrial internet of things √ routinely, clearly and sensibly assess the cyber risk for different object sorts in the dynamic digital infrastructures using artificial neural network [20] √ comparison of the agricultural upper-limb assessment, which was developed with existing assessment tools (ovako working posture investigation system and rapid entire body assessment) √ evaluated the danger of various upperlimb carriages using aula [27] √ three rounds of survey delphi, one open round and two recording rounds √ the system summarised 36 items in 6 factors: behaviour factors, general characteristics, physical function, history and environmental factors. alaa salahuddin araibi al-khwarizmi engineering journal, vol. 20, no. 3, p.p. 5970 (2024) 63 [17] simulated the ppv by utilising gene expression programming (gep) and monte carlo simulation techniques a ppv predictive model was developed using gep [18] √ comparison of pairwise and survey to create risk scores for different construction accidents √ the average of safety project performance was at 2.33-sigma 6, which suggests that 228,739 accidents may happen in every million chances [23] √ ohse risk assessment index system utilised the delphi technique, trapezoidal fuzzy number (tpfn) and set-valued statistics (svs) √ found the difficulties in ohse rm and applied the corresponding ohse risk treatments [37] √ reviewed swot studies historically, in addition to the analysis of different segments and altered approaches by swot √ filled the gap in knowledge in the strategic planning context and indicated meaningful implications for managers to help recover strategic decisions [22] √ a simple tool for listing risks that need to be considered √ [36] √ a documentation tool presented in a table that identifies possible risks with their probabilities of occurrences and effects √ presented different methods to mitigate and reverse the properties of historical and ongoing pressures through restoration measures [3] √ studied the practical costs for daily practice in the guideline-making process and financial features in addition to risk reduction by professionals √ √ √ the risk matrix method is a helpful tool for assessing impact and probability when determining preventive and investigative interventions. [35] √ new integrated fuzzy evm and fuzzy fmea approaches that combine fuzzy risk severity (frs), fuzzy risk priority score (frps) and risk rankings √ conducted risk investigation through combined fuzzy predictable value technique and proposed risk mitigation measures for critical activities [40] √ monte carlo simulation √ the nitrate concentration was relatively high and focused on agriculture and management. 3. model of risk assessments the model was designed after a wide literature review and consideration by the researchers depending on their experiences. the model, shown in figure 2, consists of three phases: definition, analysis and review of risks. fig. 2. risk assessment model. initially, brainstorming sessions were conducted to estimate the likelihood and severity of the risks to the tasks of a specific project. risk log is a relatively simple tool that was used in this model to contain and record the needed data for each risk, such as likelihood, severity and score of the risks, together with their calculations. then, the likelihood/severity matrix was applied based on the already cited concept of risk as a function of its likelihood and severity of occurrence. the four principles to create a likelihood/severity matrix are as follows [20, 21]: 1) describe the sorts and scales of likelihood and severity levels; 2) describe the sorts and scales of the output risk index; 3) create a risk score based on the following formula: risk score = likelihood rank × (severity group rank 1 + severity group rank); …(2) 4) build a depiction graphic of the likelihood/severity matrix. alaa salahuddin araibi al-khwarizmi engineering journal, vol. 20, no. 3, p.p. 5970 (2024) 64 4. results and discussion the proposed model was applied in an assembly plant of personal computers (pcs) belonging to the electrical and electronic sector in baghdad, iraq. the company follows a customised production with a production capacity of 400 pcs/year. the tree diagram of pc components is shown in figure 3. fig. 3. tree diagram of pc components. the assembly line consisted of 10 main processes, performed in sequential order as follows: fixing the motherboard (m.b.) and the power supply unit in the case; attaching the fan to the cpu and securing it to the m.b.; fixing the dvd and hdd in the case with screws; inserting svga card and ram on the m.b.; inserting the cover of the case and fixing it with screws; making all necessary cable connections; formatting and installing the windows system along with the necessary program id; running the installed system; conducting a quality control test; and packing. as detailed in table 2, it outlines the ten processes of the assembly pc line, the allocated risks for each process and the likelihood of occurrence percentage. table 2 risk log. process risk likelihood (%) fix the m.b. and the power supply unit in the case shocking the components from static electricity discharge 40 attach the fan on the cpu and fix it to the m.b. not aligning the pins correctly with the socket 45 bending the pins while installing the cpu onto the m.b. 60 incorrectly installing the cpu and the fan 50 initialisation failure due to carelessly handling the cpu 30 fix the dvd and hdd in the case with screws strain, torsion and unneeded pin/pad contact due to overtightening of screws 35 insert svga card and ram on the m.b. wrongly touching the contacts or interconnects will cause an initialisation failure 40 insert the cover of the case and fix it with screws case bending 10 cable connections error in electrical contacts 25 cutting in the wires due to its proximity to the fan 30 stopping the fan from working due to wrapping the wire around it 30 format and install the windows system and necessary program id wrong selection of windows system 10 run the installed system quality control test packing general risk: breaking parts during assembly 45 general risk: using the wrong compatible parts 30 alaa salahuddin araibi al-khwarizmi engineering journal, vol. 20, no. 3, p.p. 5970 (2024) 65 table 3 presents the data collected through direct observation, documented data and participation in the assembly process. this process was followed by consistent meetings with engineers and line workers, who were considered decision makers, to gain insight into their work environment. table 3 likelihood occurrence percentages [22]. interpretation likelihood range likelihood rank very unlikely to happen 0%–10% 1 unlikely to happen 11%–40% 2 may happen about half of the time 41%–60% 3 likely to happen 61%–90% 4 very likely to happen 9%–100% 5 in this paper, the potential risk influence was divided into two groups: likelihood and severity. the likelihood of each risk was specified based on the likelihood scale in table 3 [22] as the first step of building the risk log. for example, the ‘wrong selection of windows system’ risk was conceivable, and possible to occur but never occurred before, and for that 10% was given as a likelihood of occurrence. in the risk likelihood/severity screening, a 5 × 5-scale dimension is used for the likelihood and severity assignments, comprising five levels (1 =negligible, 2 = low, 3 = medium, 4 = high and 5 = extreme). the interpretation of the 5 × 5 risk likelihood/severity matrix for risk assessment is shown in figure 4 [23]. fig. 4. likelihood/severity matrix [23]. the likelihoods of the identified risks were ranked according to the likelihood ranking scale indicated in table 3. the ranked likelihoods were added in table 5 in the ‘likelihood rank’ column. the subsequent step involved ranking the severity of the identified risks based on their potential effects on different groups, as outlined in table 4. each company may have its criteria for evaluating risks, and in this study, the data in table 4 were tailored to the specific company under investigation. the groups identified were categorised into three main areas: employee protection, economic considerations and maintaining a marketable image. a five-point scale was utilised for each group to assess risk severity. some risks were classified under multiple groups depending on their severity levels, as detailed in table 5. the risk score for each identified risk was computed using equation 2, where the two most severe rank groups were designated as severity groups 1 and 2, and the corresponding risk scores were incorporated into table 5. alaa salahuddin araibi al-khwarizmi engineering journal, vol. 20, no. 3, p.p. 5970 (2024) 66 table 4, severity ranking. risk severity group severity description severity rank employees’ protection hardly hurt. 1 hurts can be dealt with privately. 2 hurts that require medical treatment. 3 serious hurts requiring hospital handling. 4 several serious hurts. 5 economic <0.02% of budget. 1 <0.05% of the yearly budget. 2 0.05%–5% of the yearly budget. 3 >5% of the yearly budget. 4 >20% of the yearly budget. 5 marketable image one local business is affected. 1 some local businesses in the state are affected. 2 some local businesses in various states are affected. 3 local businesses across the country are affected. 4 international businesses are affected. 5 table 5, risk score calculations. table 5 displays the outcomes of risk likelihood rank, risk severity rank and risk score for the identified risks. for the review phase of the developed model, the risk scores were positioned in the equivalent cells within the likelihood/severity matrix (figure 4) to find each severity rank (1–5) risk p r o b a b il it y r a n k ( 1 – 5 ) e m p lo y e e s’ p r o te c ti o n e c o n o m ic m a r k e ta b le i m a g e r is k s c o r e shocking the components from static electricity discharge 2 4 1 10 not aligning the pins correctly with the socket 3 1 1 6 bending the pins while installing the cpu onto the m.b. 3 1 2 9 incorrectly installed the cpu and the fan 3 1 2 9 initialisation failure due to carelessly handling the cpu 2 1 3 8 strain, torsion and unneeded pin/pad contact due to overtightening of screws 2 1 1 4 wrongly touching the contacts or interconnects will cause an initialisation failure 2 1 2 6 case bending 1 1 1 2 error in electrical contacts 2 1 1 2 6 cutting in the wires due to its proximity to the fan 2 1 2 6 stopping the fan from working due to wrapping the wire around it 2 1 2 6 wrong selection of windows system 1 1 1 breaking parts during assembly 3 3 2 2 15 using the wrong compatible parts 2 2 3 10 alaa salahuddin araibi al-khwarizmi engineering journal, vol. 20, no. 3, p.p. 5970 (2024) 67 risk criterion and control the most serious risks that require further attention and supervision. risk criteria are ‘criteria for assessing the significance of risks’ and are ‘based on the organisation’s objectives and external and internal circumstances’. they ‘can be derived from standards, legislation, policy and other requirements’ (iso guide 73) [24]. the risk criteria and their definition of detection/control that belong to this case are shown in figure 5. the results from the likelihood/severity matrix were listed in descending order according to their risk score ranks, as shown in table 6. fig. 5. risk criteria and their definition of detection/control. table 6 detected risk score and criteria colour. risk risk score risks criteria colour breaking parts during assembly 15 shocking the components from static electricity discharge 10 using the wrong compatible parts 10 bending the pins while installing the cpu onto the m.b. 9 incorrectly installed the cpu and the fan 9 initialisation failure due to carelessly handling the cpu 8 wrongly touching the contacts or interconnects will cause an initialisation failure 6 error in electrical contacts 6 cutting in the wires due to its proximity to the fan 6 stopping the fan from working due to wrapping the wire around it 6 not aligning the pins correctly with the socket 6 strain, torsion and unneeded pin/pad contact due to overtightening screws 4 case bending 2 wrong selection of windows system 1 table 6 shows that the ‘breaking parts during assembly’, ‘shocking the components from static electricity discharge’ and ‘using wrong compatible parts’ risks had the highest risk score (i.e. 1015), which were all located in the red region. these risks were followed by eight other risks located in the yellow region with less value of risk score (i.e. 6–9). risks in the red region required a risk response strategy to control the root causes and severity of these risks. the risks located in the yellow region had a moderate chance of detecting the risk event. controlling the root causes and alaa salahuddin araibi al-khwarizmi engineering journal, vol. 20, no. 3, p.p. 5970 (2024) 68 controlling the severity of the risk event were required. two risks were located in the green region, indicating a low chance of detecting the risk event and minimal to no impression. for the risk located in the blue region, its likelihood and severity could be considered little to no effect where no explicit action is required. however, a constant evaluation would be essential for the risks that occur repeatedly or show increasing severity. 5. conclusion the conclusion of the article emphasises the significant findings that align with the study’s objectives. the proposed risk assessment model was successfully applied in the electrical and electronic sector, specifically in a pc assembly line. through this application, critical risks were identified and ranked based on their likelihood and severity. the study revealed that risks such as ‘breaking parts during assembly’, ‘shocking the components from static electricity discharge’ and ‘using wrong compatible parts’ emerged as the most critical, with the highest risk scores ranging from 10 to 15. these findings underscored the urgency and severity of these risks, highlighting the need for immediate mitigation strategies. overall, the investigation demonstrated the effectiveness of the likelihood/severity matrix 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(2024) 59-70، صفحة 3، العدد20هندسية المجلدمجلة الخوارزمي ال االء صالح الدين 70 فيف منهاالتخلتقييم المخاطر و تأثيرعزيز إدارة المخاطر: االستفادة من مصفوفة االحتمالية/الت في قطاع الكهرباء واإللكترونيات ، ***هبة خالد حسين ، **هدى حاتم دلف ، *الء صالح الدين عريبيا *****محمد روسلن راحيم ،****محمد شيفل أشرول إسحاق قسم هندسة التصنيع المؤتمت، كلية الهندسة الخوارزمي، جامعة بغداد، بغداد، العراق ***,**,* و، بيرليس، ماليزيااأر, 02600كلية الهندسة الميكانيكية والتكنولوجيا، جامعة ماليزيا بيرليس، باو بوترا، **** جوهور بارو، جوهور، ماليزيا, 81310كلية الهندسة الميكانيكية، جامعة التكنولوجيا ماليزيا، ***** alaasalahudien@gmail.comالبريد االلكتروني: * huda@kecbu.uobaghdad.edu.iqالبريد االلكتروني:** hibakh@kecbu.uobaghdad.edu.iqالبريد االلكتروني:*** mshaiful@unimap.edu.myالبريد االلكتروني:**** roslan_zultech82@yahoo.comالبريد االلكتروني:***** المستخلص لية صنع م المخاطر عمبر تقييتقدم هذه الورقة المفهوم األساسي للمخاطر وتستعرض األدوات والتقنيات المطبقة بشكل شائع لتقييم المخاطر. بشكل عام، يعت الهدف .تأثيرالية/الاالحتمة . تؤكد هذه الورقة على تقنية كمية/نوعية واحدة وهي نهج مصفوفأصحاب القرارقرار تجريبية تماماً، مستندة إلى خبرة ومعرفة لهذه الورقة في همة الرئيسيةن المساهو توجيه انتباه المنظمة نحو المخاطر التي لها أكبر إمكانية للتأثير السلبي. تكم تأثيرالرئيسي من مصفوفة االحتمالية/ال طر في اتخاذ المخا ادارة ء مدراءوترتيبها الحقًا. يدعم هذا اإلجرا لتصنيف المخاطر إلى "مناطق" تأثيرتقديم نموذج مقترح يستخدم نهج مصفوفة االحتمالية/ال ديد كترونيات لتحء واإللمن خالل دراسة حالة تنتمي إلى قطاع الكهربا تأثيرقرارات مستنيرة للحد من المخاطر بفعالية. تم فحص مصفوفة االحتمالية/ال صدمة المكونات من تفريغ أظهرت النتائج أن "كسر األجزاء أثناء التجميع" و ". (pc) صيةالمخاطر الحرجة التي أعاقت خط تجميع أجهزة الكمبيوتر الشخ ذه النتائج على متخذي ". أثرت ه15إلى 10الكهرباء الساكنة" و "استخدام أجزاء متوافقة خاطئة" كانت أكثر المخاطر حرجة بدرجة خطورة تتراوح من " .مخاطر البارزةالقرار لتطوير إجراءات للتخفيف من هذه ال mailto:alaasalahudien@gmail.com mailto:mshaiful@unimap.edu.my mailto:roslan_zultech82@yahoo.com <4d6963726f736f667420576f7264202d20dae1ed20c7e1c8cfd1ed20e6c7cde3cf20e6e3dae433342d203432> al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 16, no. 3, sptember, (2020) p. p. 3442 pre-processing and surface reconstruction of points cloud based on chord angle algorithm technique ali m. al-bdairy* ahmed a. a. al-duroobi** maan a. tawfiq*** *,***department of production engineering and metallurgy/ university of technology/ baghdad / iraq . **department of prosthetics and orthotics engineering / al-nahrain university/ baghdad / iraq . *email: 70120@uotechnology.edu.iq **email: ahmed_abdulsamii7@yahoo.co.uk *** email:70057@ uotechnology.edu.iq (received 6 march 2020; accepted 5 july 2020) https://doi.org/10.22153/kej.2020.07.002 abstract although the rapid development in reverse engineering techniques, 3d laser scanners can be considered the modern technology used to digitize the 3d objects, but some troubles may be associated with this process due to the environmental noises and limitation of the used scanners. so, in this paper a data pre-processing algorithm will be proposed to obtain the necessary geometric features and mathematical representation of scanned object from its point cloud which obtained by a (matter and form) 3d’s laser scanner through isolating the noised points. the proposed algorithm based on continuous calculations of chord angle between each adjacent pair of points in points cloud. matlab program has been built for perform the introduced algorithm which implemented using a suggested case studies with cylinder and dome shape. the resulted point cloud from application the proposed algorithm, and the result of surface fitting for the case studies has been ensured the proficiency of the introduced chord angle algorithm in preprocessing of data points and clean the points cloud. where the data percent which was deleted as noised data points according to proposed chord angle algorithm was arrived to (81.52%) and (75.01%) of the total data points number in points cloud for first and second case studies, respectively. keywords: chord angle algorithm, point cloud, surface reconstruction. 1. introduction as result to developments of 3d laser scanners in previous years, were pushed the interesting to obtain a surfaces representations and reconstructions of the 3d parts from its points cloud was obtained by such techniques. however, this points cloud is involving some unnecessary and noisy data points, due to the resolution of some scanners and the reflectivity property of the scanned surfaces, also the contrast problems. point cloud acquiring using a 3d laser scanner may be contained more information for a ten of thousands of massive data, so that, the huge data points in cloud which used to surface model reconstruction, subsequent processing, and storage, represent the main difficulties in 3d laser scanning process [1]. in other word, not all of the data points can be used in follow-up process. therefore, there is need to extract only the data point clouds which reflect the surface of scanned shape, and removing the redundant data points. therefore, it’s essential to determine the noisy data and delete it for the points cloud set, as manner to gives the pretty representations of the 3d scanned surfaces, and remining the required geometrical features for surface. so, that, the pre-processing of 3d points cloud and reconstruction of surface from these points cloud, has more attention of researchers in this domain. ali m. al-bdairy al-khwarizmi engineering journal, vol. 16, no. 3, p.p. 3442 (2020) 35 many researchers showed in their literatures different algorithms for simplification of data points obtained from 3d laser scanners. j. liu et al [2] proposed an effective and simple reconstruction algorithm based on interpolation of b-spline surfaces of blade surface by section curves with less acquired points, to improve the aerodynamic performance for the blade surfaces. the less acquired points of the section curves were gritted using the coordinate measuring machine. b. cyganek et al [3] proposed an approach for classification of multidimensional data to allow complex structures processing. this method is depended on a tensor kernel which applied to train of the support vector machines (svm) and sequential minimal optimization (smo) also based on a kernel of chord distances. m. xiao et al [4] provided a surface flattening algorithm to detect the damage or deterioration on the tunnel’s inner wall, started with the reconstruction of surface triangular mesh from the 3d point cloud data, based on mechanics revision to ensure the railway of transportation operations. z. kang et al [5] proposed an interpolation approach to extract the central axis and wall cross-sectional points of the tunnel, that depended on the quadric parametric surfaces fitting using the 2d projections of the points cloud with curves fitting to obtain the tunnel central axis, also the intersections of arbitrary straight lines to tunnel points cloud was used to getting the crosssectional surfaces. f. bernard et al [6] presented a methodology for object’s shape or surface reconstruction from a given sparse surface points using a statistical shape model (ssm) which represented by surface mesh and a point distribution model (pdm). the methodology classified the given points according to the surface normal based on surface-based fitting process, using gaussian mixture model (gmm). d. xia et al [7] performed numerical and analytical investigations to reduce the noise data properties for regions-of-interest (roi), and reconstruct the images based on chord image reconstructions using different scanning configurations. s. gauthier et al [8] proposed a method based on analyze and segment the digitized 3d surface mesh curvature histogram using a real object through detecting the peak and valley primitives, also proposed to use the curvature histogram analysis to measure the quality of mesh for a lot of reverse engineering steps, which could be used to construct the cad model. c. mineo et al [9], suggests a filtering approach to identify the boundary points and spatial procedure that use fast fourier transform (fft), the approach generate the tessellated surfaces directly without noise from the points cloud data by detecting the points of the sharp and creases edges. k. w. lee and p. bo [10] introduce a procedure to reconstruction the feature curves by intersections of determined strip pairs to approximates the regions beside the features to obtain a smooth feature curves from points cloud of model. a. duroobi et al [11] presented a practical method to obtain the control points to derive a representation equation for the profile using bezier technique from a huge data as a reverse engineering application, also the author used the image modifications process by solid work package to perform the dimensional comparison. d. a. mahmood et al [12] proposed a method for determining the measuring positions of cmm probe which was depend on the articulated arm coordinate measuring(aacmm)machine and kinematics calculations of the used robot, it’s found the proposed method was accurate and precise and eliminate the design error effects. due to the problems which associated to the 3d scanning process there are some of un necessary information data need to be manipulated. so, present work proposes a data point cloud pre-processing algorithm which based on calculation of the chord angle for simplifying the stream lines of point cloud. which will be acquired using a 3d laser scanner, to determine the necessary points for representing the geometrical information of the scanned object. also, to detect and neglect the noisy points in point cloud, then obtaining the real surface representation equations which of the selected case studies as a benefit of reverse engineering domain. the introduced paper is organized as follows, section 2 divided into two subsections; section-i covers a short review on the chord angle algorithm methodology, and subsection-ii presents the detail of the proposed algorithm and its implementation in matlab environment. section 3 tests the validity of the proposed algorithm through the selected case studies. sections 4 records and analyzes the results obtained for selected case studies. finally, section 5 presents evaluation and conclusion of the proposed algorithm in according to the obtained results. ali m. al-bdairy al-khwarizmi engineering journal, vol. 16, no. 3, p.p. 3442 (2020) 36 2. chord angle algorithm the chord angle algorithm is simplest and more effective algorithm to manipulate the obtained points cloud by the 3d laser scanners to determine the noisy points. the algorithm is based on calculating the maximum chord angle value between each pair of adjacent points in point cloud. then compare this value with precomputed allowed permissible chord deviation angle (∆α). i. chord angle algorithm methodology the chord angle will be calculated continuously between each set of three adjacent points (po, p1, and p2), and the value of each calculated angle will be compared with the preset value of chord angle(∆α). whether the value of angle (α) is smaller than or equal to (∆α) such as (αo) and (α1), the set of adjacent point will be recorded as the needed points, while if the value of angle (α) is larger than (∆α) such as (α2), then the middle point(p3) will be neglected as a noise point and taken the points (p2, p4, andp5) to calculate the next chord angle, this procedure illustrated in figure 1. the process will be proceeded until all data point included in the sequence. figure 2 illustrates the difference between chord height and chord angle where for the same set of three adjacent points it could be have the same value of chord height but it has a different chord angle, depending on the distance between each two point in point cloud. where the chord height (ho) term for a set of points represent the shortest distance between pi+1 and the line that connect the pi and pi+2. fig. 1. demonstrate the chord angle algorithm. fig. 2. the different chord angles for the same chord height. as result to application the chord angle algorithm the noise or scattered points can be detect and ignore from the resulted point cloud. the chord angle algorithm can be applied by sequential steps as shown in figure 3 which are: • input the row point cloud • set the iteration i for the points in point cloud • set the allowable value of chord angle (∆α), depending on accuracy that adopted. • construct the vectors v1 and v2 between the points p0, p2 and p1, p2 respectively as [13]. …(1) …(2) where: (xo, yo, zo), (x1, y1, z1), and (x2, y2, z2) are the coordinates of the first, second and third point respectively in the point cloud. • compute the dot product between the vectors v1 and v2 as …(3) • compute the angle(α) between v1 and v2 vectors using the formula …(4) p2 p1 p0 p’0 ho d0 d’0 α α'0 p3 po p1 p2 p3 α o α 1 α 2 noise point noised curve not noised p4 p5 ali m. al-bdairy al-khwarizmi engineering journal, vol. 16, no. 3, p.p. 3442 (2020) 37 fig. 3. flowchart for proposed chord angle pre-processing algorithm. • if α1≥(∆α), save p1, then go to next assessment, and calculate the height of chord p1p2p3 according to the same procedure and carry on assessment, • if α1<(∆α), delete p1, and calculate the chord angle of point set pop2p3, namely α2. • proceed process until the last point (n) of the scanning line. these points which don’t accord with the requirement of chord angle value will be neglected. ii. proposed program of the chord angle algorithm a matlab program is constructed to achieve the methodology of the adopted chord angle simplifying algorithm. figure 3 illustrate the flowchart and general steps of the proposed program, where the constructed program begin to receiving the data points as a points cloud which acquired using a 3d laser scanners devices. then compute the allowable chord angle value automatically within the program, after that the chord angle for each set of three adjacent points in point cloud will be computed using the illustrated methodology procedure in section i. input the data point pi, pi+1, pi+2,..., pn |∆α | ≤ αi input value of allowable chord height (∆α) determine the equations of vectors v(i),v(i+1),…., compute the dot product of each neighboring vectors eq. (3) find the angle (αi) between the neighboring vectors eq. ( 4) i=i+1 delete pi+1 save pi+1 i=i+1 let iteration (i)=1 start end yes no i ≥ n yes no ali m. al-bdairy al-khwarizmi engineering journal, vol. 16, no. 3, p.p. 3442 (2020) 38 finally, the decision will be made according the comparison between the calculated and allowable chord angle assessment. 3. suggested case studies to prove the effectiveness of the adopted algorithm for pre-processing the point cloud, two case studies with shape cylinder and dome were selected as shown in figure 4 and figure 5. the case studies had been scanned by a laser scanner device named (matter and form). the output scanning file of the studied case studies were saved as points cloud of data point with format (‘file name’. xyz) in 3d’s coordinate by the scanner software ‘matter and form’, then the output file was processed in ‘excel’ program to save in (.xlsx) format, after that the file has been opened within ‘matlab’ program to perform the pre-process with the chord angle algorithm and saved as a data file (‘file name.dat.’). the file of the first case study (cylinder) has been involved (527884) as total points number of in the, after completing the scanning process, while the file of second case study (dome) has (1082908) as the total points number. fig. 4. cylinder case study. fig. 5. dome case study. figure 6 shows the scanned shape of the first case study (cylinder) after completing scanning process, while figure 7 illustrates the scanning process of the second case study that is contained an unperfect and loosed scanning data, also presence a noise points. the purpose of the proposed simplifying algorithm is to identifying and deleting the noisy points which is appear in figure 6 and figure 7 as red points, which are needed to processed and deleted with respect to the criteria of the adopted algorithm. fig. 6. noise points in cylinder case study. fig. 7. noise points in dome case study. scanner device case study calibration board case study case study scanner device case study calibration board ali m. al-bdairy al-khwarizmi engineering journal, vol. 16, no. 3, p.p. 3442 (2020) 39 4. results and discussions from the results of application of the proposed chord angle algorithm for simplifying the points cloud, the first file belong to cylinder case study was contains only(97528) total points, for just single pre-processing attempt also the noise points percent was equal to (81.52%), which was ignored as an unrequired points, while the dome case study file was contains (270532) points and the deleted points percent become (75.01%), when executing the adopted algorithm for one attempts. these results of the selected two case studies proved the effectiveness of the adopted algorithm to simplifying the data points through identifying and deleting the unrequired noisy points. this indicates that the adopted algorithm is very efficient to simplifying the data points and deleting the unnecessary noisy points. the final result of the simplifying process for the proposed case studies is shown in figure 8 and 9 for the point clouds of the two selected case studies. fig. 8. cloud points for cylinder case study. fig. 9. cloud points for dome case study. the obtaining point clouds which were resulted from application the introduced chord angle algorithm were used to gives the surface representations of the studied case studies using the facilities of matlab program. and the resulted equations for fitting 1cylinder case study: 3d degree of an linear polynomial for x and y direction: …�5� the coefficients of the polynomial are inserted in table 1. table 1, coefficients of polynomial of the first case study (cylinder). 2dome case study : 3d degree of linear polynomial equation for x and y direction: …�6� coefficient p00 p10 p01 p20 p11 p02 p30 p21 p12 p03 value 0 .5 5 8 7 -0 .1 9 1 6 0 .2 5 0 .0 5 7 6 3 -0 .0 0 6 8 6 4 0 .0 5 5 9 3 0 .0 0 0 1 2 8 -0 .0 0 1 3 1 4 0 .0 0 0 4 4 0 2 -0 .0 0 0 3 8 ali m. al-bdairy al-khwarizmi engineering journal, vol. 16, no. 3, p.p. 3442 (2020) 40 and the polynomial coefficients are listed in table 2. table 2, coefficients of polynomial of the second case study (dome). after achieving the pre-processing algorithms for the proposed case studies, and completing the simplification process, a surface reconstruction process for intended case studies was done with facilities which associated within meshlab program as shown in figures 10 and 11 for cylinder and dome respectively. fig.10. reconstructed surface model of cylinder shape case study. fig. 11. reconstructed surface model of dome shape case study. 5. conclusions acquiring process of 3d data by a 3d modern laser scanners devices is important to regeneration process of parts as a reverse engineering application, but there is some unclear detailed data, such as noisy points in obtained points cloud of the scanned parts, which associated to the scanning process. so, it’s necessary to process and simplify the obtained data from these devices using a number of simplifying and pre-processing approaches. the introduced paper, present a data pre-processing and simplifying algorithm to extract only the required points to generate the geometrical representations of scanned parts, the adopted algorithm depended on the sequential calculations of chord angle value for each set of three contiguous points in the points cloud. the obtained results by the surface fitting, and the percent of detected noisy points were illustrated that, the adopted algorithm was very efficient in pre-processing and simplifying the points cloud for any other case study. the total points number of the first suggested case study (cylinder) was (527884) points which becomes (97528) points after applying the adopted chord angle algorithm, and the deleted points percent was about (81.52%), of total number of data points, while the scanned file of the second case study (dome) was involved (1082908) points, then the points number becomes (270532) after applying the adopted chord angle algorithm, with proficiency (75.01%). coefficient p00 p10 p01 p20 p11 p02 p30 p21 p12 p03 value 0 .0 2 0 1 0 .4 4 0 3 0 .0 7 0 8 2 0 .0 6 5 2 7 -0 .0 0 1 3 0 7 0 .0 6 8 8 4 -0 .0 0 0 3 1 6 7 -0 .0 0 0 4 8 9 7 -0 .0 0 0 4 6 4 3 -0 .0 0 0 4 7 3 1 ali m. al-bdairy al-khwarizmi engineering journal, vol. 16, no. 3, p.p. 3442 (2020) 41 6. references [1] g. wang, y. lv, n. han, and d. zhang, “simplification method and application of 3d laser scan point cloud data’’, international conference on mechanical engineering and material science, mems, 2012. [2] j. liu, j. zhao, x. yang, j. liu, x. qu, and x. wang, “a reconstruction algorithm for blade surface based on less measured points”, hindawi publishing corporation, ijae, international journal of aerospace engineering, vol. 2015, article id 431824, 2015. [3] b. cyganek, b. krawczyk, and m. woźniak, “multidimensional data classification with chordal distance based kernel and support vector machines”, elsevier, eaai, engineering applications of artificial intelligence, vol. 46 pp. 10–22, 2015. [4] m. xiao, z. qi, and h. shi, “the surface flattening based on mechanics revision of the tunnel 3d point cloud data from laser scanner”, elsevier, procedia computer science, vol. 131, pp. 1229–1237, 2018. [5] z. kang, l. zhang , l. tuo, b. wang and j. chen, “continuous extraction of subway tunnel cross sections based on terrestrial point clouds “, remote sensing journal, vol. 2072-4292, pp. 857-879, 2014 . 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[11] a. duroobi et al, “reverse engineering representation using an image processing modification’’, baghdad university alkhwarizmi engineering journal, vol. 15, pp. 56-62 , 2019. [12] d. a. mahmood et al, “improving reverse engineering processes by using articulated arm coordinate measuring machine’’, baghdad university al-khwarizmi engineering journal, vol. 16, pps. 42-54 , 2020. [13] p. comninos, “mathematical and computer programming techniques for computer graphics”, springer, verlag, london, 2006. � ا���ري� �� � 3ا���د، ����16 ا���ارز�� ا���� �� ا����� ��� ��� ،42 -34 )2020( 42 د �� ��ارز����!�" #� ا��. ط وا� دة *()�' ا�&%�ح # ��� ا��&�.� �&� ا�� *.��� زاو/� ا��*( � ا���/(ي* � �� 7 � #� *�5�6*** ** � ��� ا�&��4 ��� ا��ھ ب ا��رو#�ا1� ��� ��� ا��7اق/ 5�4�& ا�#3(012�2&/ /.)اد-,+ ھ()'& ا%$#�ج وا� ��دن /ا�*،*** ا��7اق/ $)/ 1�4�& ا�(?7<=/ /.)ادا�>(�;0& وا� ,�ھ()'& ا:ط7اف ,+** 70120@uotechnology.edu.iq :a$7<) ا%�3#7وbا�* ahmed_abdulsamii7@yahoo.co.uk :a$7<) ا%�3#7وbا�** 70057@ uotechnology.edu.iq و$a:*ا�7b<) ا7#3�%** �� ا��8 +c7��/ (d#, ا� &e>(fا� ��ت ا�0l2m& ا�j0kر<& 0ghg& ا:/��د ا�012�2)3#f'��ر ا� b#;0,3& ، < 3= ا�ت ا�?()'& ا��0)op aq r>7,2ر ا�s#4& �7(& 4= ا� t0bء ا��v2mا� wb,/ &0k �ه ا�yھ zq7اp a#ا� [\��ت ا�0l2m& ا� ,#a�y� .&4(d ، ا1%,�م 0ghg& ا:/��د ، و�23p (=3ن ھ(�ك /�^ ا� [f'�0& وf4)دات ا� dا� ck; 2ل<fk� ت�$�0bk� &ob, 5& ا���� k� &042ارزf ا-#7اح +p ، hfbه ا�yھ aqil�ا� ,2ح ا�5,+وا�# 0e] ا�7<�av �[3] ا�7mور<&ا�?()'0& > �ً0l2v +p a#0& ا�so)ا� k#/�f' =4p�?k0<f ام(d#'��دaghg ا:/� يj0ر�kا �'l ا�/ )matter and formط (�o)ل ا�j; لhf =4&0l�v2m2ارز04& ا�dا� . cإ� ()#,p &o7#o ت ا�ا��/�,fا�&/�f' aq ورة��ط ا� 5o)7 /0= \] زوج 4= ا�p2او<& ا�j� ط ,# 7ة�o)4ا���ء /$7)/ +p .ام(d#'�/ q matlab :ز�5$ �'#d)ام / ��%ت درا'0&ا�2dارز04& ا� o7#o& ا�#y0r)p +p aھo 4 &o7#oذات so)ا� &/�f' .&b-2ا$& وs'3] اtط� &o7#o 2ارز04& ا�dا� z0bsp =4 &5p�ا�( �%ت ا�)را'0& &ا�,lh 0fs &و$#�ql ا�fk� ء�r\ u#bgةأ &ob, 5& ا����/& �2fارز04& زاو<& ا�7p2 ا� aq &o7#o ا� �f' w0x)pت و�$�0bkط�o)ا� h0o ،u$�\ +p a#ت ا��$�0bk� &>2t ا� &b,)اھا��?�� q0& وl�v2v ط�o)\) cإ� &o7#o 7 ا�p22ارز04& زاو<& ا�d� �ًoت ٧٥.٠١٪) و (٨١.٥٢�$�0bط ا��o$ د(; a��٪) 4= إ1 &0so)ا� &/�f,ا� aq&0'ا�)را &��fk� aا�#2ا� ck; &0$�eوا� cا:و�. this is an open access article under the cc by license : al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 21, no. 3, september, (2025), pp. 106117 pulse wave speed estimation: a comparative study of the pu-loop technique versus tensile and compliance testing on synthetic elastic tubes 3zubaedi-wesam aland , 2, falah alzuwaid*1wisam s. hacham 1 mechatronics engineering department, al-khwarizmi college of engineering, university of baghdad, baghdad, iraq 2 trafford and stockport college group (tscg), stretford, construction & sustainability, manchester, united kingdom 3 wigan and leigh college, united kingdom *corresponding author’s email: wisam@kecbu.uobaghdad.edu.iq (received 16 june 2025; revised 26 july 2025; accepted 3 august 2025; published 1 september 2025) https://doi.org/10.22153/kej.2025.08.003 abstract pulse wave speed (c) is a key variable in haemodynamics and cardiovascular system analysis. it is directly related to arterial elasticity and inversely to distensibility of the arterial lumen. the pressure–velocity loop (pu-loop), derived from simultaneous velocity (u) and pressure (p) measurements, is used to estimate c, leveraging the linear u–p relationship during early systole, when reflected waves are absent due to bifurcations and/or occlusion. the pu-loop method was validated using tensile and compliance testing. tensile testing, using a load cell, estimated young’s modulus (e) of synthetic elastic tubes, allowing c calculation using the moens–korteweg equation. compliance testing under static pressure assessed the relation between p and volume (v). this relationship predicted the compression and contraction courses, validating the testing applied to the lumen of the particular flexible tube. consequently—to calculate the distensibility of the flexible tube lumen—the change in internal lumen volume due to the change in p was used, hence c corresponding to the bramwell–hill equation. despite limitations such as sample size of tested specimens, experimental conditions not fully physiological, sensitivity of testing due to measurement noise; neglecting anisotropicity and heterogeneity of vessels; not accounting for the full complexity of real arterial behaviour and the use of synthetic elastic tubes stiffer than in vivo lumens, the calculated c (ccalculated), using the pu-loop technique, was in agreement with values acquired from complianceand tensile-testing-based calculations. according to compliance and tension testing, the velocity of c was 19.5±0.05 and 19.5±0.012.1 m/s, respectively. using the pu-loop technique, it was 20±0.25 m/s. these results validate the pu-loop methodology in c assessment. keywords: bramwell–hill equation; compliance testing; moens–korteweg equation; pu-loop; tensile testing. 1. introduction pulse wave velocity (c) has emerged as a critical clinical biomarker for assessing arterial stiffness, a robust predictor of cardiovascular morbidity. as the velocity at which pressure waves propagate through the arterial tree, c reflects the elastic properties of the vascular wall and is directly influenced by structural and functional changes in the arteries. elevated c values are strongly associated with increased arterial stiffness and have been independently linked to a heightened risk of cardiovascular events, including hypertension, stroke and heart failure. due to its mailto:wisam@kecbu.uobaghdad.edu.iq https://doi.org/10.22153/kej.2025.08.003 https://doi.org/10.22153/kej.2025.08.003 wisam s. hacham al-khwarizmi engineering journal, vol. 21, no. 3, p.p. 106-117 (2025) 107 non-invasive nature and predictive value, c is increasingly used in clinical practice and research settings to evaluate vascular aging, monitor disease progression and guide therapeutic interventions. therefore, accurate and reproducible estimation of c is highly essential for early detection and risk stratification in cardiovascular practice. moreover, precise determination of c is crucial for optimising the separation of variables in wave intensity analysis, a widely used methodology in haemodynamic studies. the reliability of this technique depends on the accurate calculation of c, which characterises the traveling wave within the arterial lumen. methods for determining c typically fall into two categories: estimation based on arterial geometry, dimensions and elastic properties, and transit time measurements between two locations. each approach has its own advantages and limitations. transit time-based methods offer non-invasive average values of c across the measurement sites. by contrast, geometry-based methods require invasive measurements, which are difficult clinically. c is a widely recognised clinical measure of arterial stiffness and plays a crucial role in assessing cardiovascular risk and vascular health [1, 2, 3]. numerous methodologies have been developed to quantify local_c (clocal) and regional_c (cregional), including sequential ultrasound-based measurements of diameter and velocity [4], forward-traveling pulse wave analysis [5] and pressure–volume loop (pu-loop) techniques [6]. the pu-loop method has been extensively investigated, revealing that wave reflections can lead to underestimation or overestimation of c, necessitating refined analytical corrections [7, 8]. modelling and simulation studies enhanced our understanding of arterial haemodynamics, with simplified 1d models capturing complex wave interactions within the arterial network [9, 10]. additional studies have demonstrated the influence of blood pressure on c, underscoring the importance of accounting for haemodynamic variability during clinical assessments [11, 12]. recent recommendations emphasise the importance of standardises validation for noninvasive measurement devices [13] and highlight that (c) can effectively guide clinical decisions in cardiovascular disease management [14]. comparative analyses have highlighted differences in measurement techniques [15, 16], and largescale studies have confirmed c’s clinical relevance across diverse populations [17, 18]. collectively, this body of evidence forms a robust foundation for the present study’s focus on refining c measurement techniques and their application in cardiovascular risk stratification. c is a widely used biomarker of arterial stiffness and cardiovascular risk. various methodologies were developed to measure it in vivo and in silico. recent studies have underscored the importance of clocal measurements within the arterial tree for assessing regional differences in arterial stiffness [19], whereas techniques, such as pulse wave imaging, provide non-invasive and quantitative assessment of arterial stiffness in real time [20]. elevated c has been shown to correlate with cognitive decline in elderly patients, highlighting its potential as a clinical tool for broader health assessments [21]. in addition, it has been utilised as a clinical measure to aid material characterization of vascular tissues [22], emphasising its role in diagnostic and research contexts. real-time measurements of aortic c during exercise stress testing further expand its utility in dynamic physiological conditions [23]. computational modelling frameworks, such as those developed by bogatu et al. [24], have also contributed significantly to understanding c and arterial stiffness by simulating complex haemodynamic interactions. the distinction between central and peripheral arterial stiffness has been recognised as a critical factor in cardiovascular assessment, with early studies by woodman et al. [25] illustrating the importance of site-specific measurements. the comparative studies of methodologies—including the landmark work by salvi et al. [26]—have highlighted the need for standardisation and validation of c measurement techniques to ensure reliability and clinical applicability. finally, janjua et al. [6] introduced a novel noninvasive method for estimating clocal using pressure–volume loop analysis. pressure–volume loops were developed by simultaneously measuring pressure and flow waveforms at the same arterial site, thereby deriving clocal values. the researcher applied this technique to palmar digital arteries, showcasing its feasibility and potential for assessing arterial stiffness in peripheral vessels. the method offers a promising approach for non-invasively evaluating vascular health, particularly in settings where ctraditional measurement techniques may be challenging to implement. in the arterial system, following the transmission of the initial compression wave and preceding the arrival of the backward pulse wave, which originates from discontinuities at reflection sites and returns to the measurement location, a period during cardiac systole exists when only wisam s. hacham al-khwarizmi engineering journal, vol. 21, no. 3, p.p. 106-117 (2025) 108 forward waves are present. this time interval can be identified by examining the slope of the linear portion of the u–p loop during early cardiac systole [27]. the problem statement of this comparative study is to validate the application of the pu-loop technique for estimating c, with accuracy comparable to conventional mechanical testing approaches (e.g., tensile and compliance testing) under the static pressure conditions, when applied to synthetic elastic tubes. this validation required the estimation of the elastic properties of the synthetic flexible lumen. the moens–korteweg [28] and bramwell–hill [27] equations were applied to calculate pulse wave speed using compliance and tensile testing. the moens– korteweg equation requires knowledge of young’s modulus of elasticity, which was determined using a load cell (instron high, wycombe, uk). the bramwell–hill equation requires specification of the lumen’s distensibility, which was obtained by performing a compliance test on the wall of the selected elastic rubber tube. 2. methodology the theoretical basis for calculating c is grounded in classical wave propagation theory, with the moens–korteweg and bramwell–hill equations representing the most widely accepted analytical models. these equations establish the relationship between c and the mechanical properties of the vessel wall and the enclosed fluid, subject to specific assumptions. the magnitude of c is quantified using the pu-loop technique, described in the following section. to validate this technique, bramwell–hill and moens–korteweg equations are used to determine c. methodological differences may lead to variations in the estimated values of c. dynamic techniques (e.g., pu-loop) assess c during the active phase of the cardiac cycle, reflecting realtime haemodynamic behaviour. by contrast, static approaches (e.g., tensile/compliance testing) derive c from passive vessel mechanics. 2.1 wave speed determination khir et al. [29] originally presented the pu-loop technique. this method relies on the linearity between u and p of the pulse wave at the time interval where no backward reflected waves are present (e.g., early systolic upstroke where reflection effects are minimal). accordingly, c can be written as follows: c = ± (dp/ρdu)linear portion …(1) in equation 1, dp and du represent the derivatives of p and u for any two consecutive sampling of the time interval during the early systole, respectively, and (ρ) indicates the fluid density. the time lag between p and u was accounted for prior to the analysis and was found to be ~6 ms. the time lag is caused by the dissimilarity of the frequency response of the measurement system. the moens–korteweg equation results from elastic wave propagation theory for thin-walled cylindrical vessels. this formula is based on the following assumptions about the tube: it must be thin-walled, linearly elastic, incompressible and of uniform cylindrical shape. it is particularly wellsuited to synthetic rubber tubes, which are apt to satisfy these assumptions in planned laboratory tests. the physical interpretability and general simplicity of this formula render it an excellent model for benchmarking mechanical behaviour in isotropic, homogeneous materials. this equation enables the calculation of c using the mechanical dimensions and properties of the tube lumen, expressed as follows: c = (e.h/ρ.d)1/2 …(2) where d, e and h represent the uniform inner diameter, young’s modulus of elasticity and the tube wall thickness, respectively. bramwell–hill equation: this equation is a relation between c and changes in vessel volume and pressure, but it is addressed to the fluid–vessel system compressibility and is best applied with pressure–volume data. it is also derived under the assumptions of axisymmetry and incompressibility of the vessel, which are reasonably well satisfied in experiments conducted on elastic–plastic tubes. this equation permits estimating c provided that the static pressure difference (dp) during compression and retraction strokes, as well as the volume change (dv) from the initial volume (vo) are available. this equation can be written as follows: c = (dp.v0/ρ.dv)1/2 …(3) the application of the two traditional equations to synthetic rubber models is justified by their material uniformity, incompressibility and geometric simplicity, fitting closely the theoretical approximations of both models. consequently, they provide a solid foundation for evaluating experimental methods and calibrating measurement systems prior to their application to wisam s. hacham al-khwarizmi engineering journal, vol. 21, no. 3, p.p. 106-117 (2025) 109 more complex and biologically realistic geometries, an observation that holds true in our test setup. 2.2 experimental setups 2.2.1 long tube setup the experimental setup used to estimate c utilising the pu-loop technique is shown in fig. 1 [30]. all elements of the experiment are arranged on the same horizontal platform. the schematic illustrates the following key components: 1. reciprocating pump that mimics the cardiac function; 2. location of the haemostat valve; 3. catheter for pressure measurement at the designated site; 4. control unit of the pressure transducer [catheter]; 5. flow probe positioned 25 cm downstream from the inlet of the selected synthetic tube; 6. control unit for the flow probe; 7. bnc cable; 8. computer running labview software; 9. secondary tube, 800 cm in length; 10. selected tube, 192 cm in length. reservoirs: in this experiment, two containers were used. one was positioned at the end of the subordinated tube to compensate for and contain the volume of water displaced during the forward (compression) and backward (retraction) strokes of the pump’s piston. the other was placed directly downstream of the system pump and was used to include the main selected synthetic tube. water was selected as the working fluid due to its ease of use, replicability and compatibility with sensors. whilst fluids with blood-mimicking viscosity could yield more physiologically relevant data, the primary requirement in the governing equations is the fluid’s density. water, with a density of 1000 kg/m3, closely approximates that of blood, which is approximately 1060 kg/m3. a roughly half-sinusoidal pulse was generated in the forward direction using a syringe-based reciprocating pump, which was linked and driven by a scotch yoke mechanism by means of an electric actuator (maxon, dc-max, swiss) powered a 12-volt alternating current supply. in all experiments, a single forward pulse was delivered at a frequency of 1.1 hz. the injected water volume was approximately 40 cc over a duration of 0.9 s. pressure was measured using a transducertipped catheter (gaeltec, scotland, uk), positioned 25 cm downstream from the inlet of the main tube. flow velocity was recorded using ultrasound probes and a flowmeter control unit (transonic, ht323, ny, usa). simultaneous measurements of pressure and flow were taken at the same location, 25 cm downstream of the tube inlet. to acquire the measured data, the labview program was applied at a sampling rate of 500 hz. these data were gained using the national instruments (bnc-2090 daq, texas, usa) system. matlab software was used to write offline programs to analyse the measured data. fig. 1. experimental setup schematic for estimating c, using the pu-loop technique, indicating all components. main and secondary synthetic rubber tubes connected in line with the pump and cylindrical reservoir. catheter insertion can lead to localised pressure loss or flow disruption within the vessel, potentially compromising the fidelity of pressure waveforms and altering the physiological haemodynamic environment. such effects must be carefully considered, particularly in in vitro experiments or in vivo applications where precise pressure waveforms are essential for interpretation. wisam s. hacham al-khwarizmi engineering journal, vol. 21, no. 3, p.p. 106-117 (2025) 110 to mitigate these issues, we minimised the insertion depth, maintained straight tubing alignment and calibrated the pressure sensor postinsertion to compensate for baseline offset. elastic tubes: in this experiment, the main synthetic tube featured an isotropic, circular crosssectional area along its 192 cm length. the tube wall was uniformly in 0.2 cm thick, with an inner diameter of 1.7 cm. a secondary uniform-lumen tube measured 400, 1 and 0.2 cm in length, diameter and wall thickness, respectively. both tubes were composed of flexible rubber [health care, uk], selected based on availability, elastic behaviour and reproducibility of mechanical properties, criteria suitable for conducting repeatable pulse wave propagation experiments. 2.2.2 tensile testing setup elastic rubber vessel flexibility was characterised through uniaxial tension testing, an appropriate method given the cylindrical structure and physiological loading conditions. bending tests were deemed unnecessary because the vessel would not be subjected to flexural stresses under normal operating conditions. calculation of the modulus of elasticity enabled the application of the m-k equation to calculate c. young’s modulus (e) of the main tube was measured using tensile testing with an appropriate servo load cell (instron high wycombe, uk). the relationship between applied load and corresponding extension was recorded using the instron software (bluehill2), yielding an estimated e value of 3.3 mpa. the tested specimens had wall thickness, inner diameter and width of 0.2, 1.7 and 0.75 cm, respectively, as illustrated in table 1. tmax., lmax., yts and ly in table 1 represent the tensile stress at the maximum thickness, maximum load, yield tensile stress and load at yield, respectively. the experiments comprised primarily three tests on the identical segments. however, in some instances, four tests were conducted, depending on the level of comfort with the gathered data. prior to formal testing, specimens underwent a warm-up procedure involving repeated cycles of stretching and relaxation. this step was essential to eliminate any defects or manufacturing-induced tears that could compromise the accuracy of the measured modulus of elasticity. table 1, tensile test results for the tested elastic synthetic tube. mpa means 106 pascals. 2.2.3 compliance testing setup in this work, the test was not used to validate the hypothesis that reduced arterial compliance contributes to significant atherosclerotic diseases, as emphasised by recent studies. instead, it was employed to estimate the elastance of the selected synthetic flexible tube, enabling quantification of the magnitude of c that governs flow propagation through the tube. the static pressure difference (dp) during compression and retraction procedures, along with the corresponding volume change (dv), were obtained using the setup shown in fig. 2. consequently, c will be calculated through the synthetic elastic tube using the bramwell–hill equation [27]. fig. 2. experimental setup applied, estimating compliance testing-based-pulse wave speed for the selected synthetic flexible tube, indicating all parts. tmax. (mpa) lmax. (n) yts (mpa) ly (n) young’s modulus (mpa) 6.2±0.015 180±0.20 5.9±0.015 180±0.2 3.3±0.012 wisam s. hacham al-khwarizmi engineering journal, vol. 21, no. 3, p.p. 106-117 (2025) 111 2.2.4 instrumentation calibration procedures calibration procedures were conducted prior to each trial to ensure measurement reproducibility, accuracy and data reliability under strict experimental test conditions. the catheter was positioned adjacent to a fixed column of water and used as a reference standard. output voltage from the catheter was recorded at 10 cm incremental heights of the water column, corresponding to known pressures (1 cm h₂o = 98.1 pa). a voltage–pressure calibration curve was constructed using linear regression, rendering the catheter response linear and drift-free. the calibration plot served as the basis for transforming catheter voltage output into precise pressure readings throughout the experimental tests . the load cell was calibrated using a certified calibration weight under tension and compression modes. the test machine software (instron bluehill or equivalent) automatically generated a calibration curve by correlating measured force with known weights, enabling precise force measurements within the range specified by the load cell. zero-load stability was also verified intermittently before and after the test . velocity sensors, used in the pu-loop setup, were calibrated using a pulsatile flow generator, providing repeatable and controlled velocity profiles. the output of the sensor was calibrated against a reference ultrasonic doppler velocimeter or a known flow rate in a precision syringe pump system. the output voltage of the velocity sensor was referenced to actual velocity values (in m/s) to obtain the calibration function. sensors were also positioned at the centreline of flow so that they could have maximum accuracy. 2.2.5 standardisation and adaptation of testing to ensure consistency, accuracy and replicability of the mechanical properties of the synthetic materials used in this comparative study, standardised testing procedures were implemented and selectively adjusted. tensile tests on the elastomeric tubes were conducted with reference to astm d412, which outlines procedures for determining the tensile properties of vulcanised rubber and thermoplastic elastomers [31]. this standard provides recommendations for testing tensile strength, elongation and modulus as well as for specimen preparation and strain rate. here, synthetic rubber tubes were tested on a universal testing machine with flat grips at 500 mm/min extension rate, following method a of astm d412. however, due to the tubular form of the specimens, some modifications were made to accommodate circular cross-sections and prevent slippage or localised deformation during the tests. special fixtures were employed to prevent stress concentrations at the grip areas and to achieve axial alignment . pressure–volume characterisation was carried out with reference to iso 9276-1, providing general principles for describing the relationship between applied pressure and resulting volume changes for materials [32]. although originally developed for particulate systems, the general approach of defining the pressure–volume relationship was adhered to characterise the elastic behaviour of the synthetic tubes under internal pressurisation. incremental pressures were applied through a controlled pump system, and the ensuing volume displacement was quantified using calibrated syringes and high-resolution imaging to track radial deformation. the incompressibility of the tubes and their homogeneous wall structure enabled the faithful implementation of the modified protocol . these adjustments allowed the use of widely acceptable standards and the alteration of the procedures to the geometry and the mechanical qualities of the synthetic models. thus, the experimental results were not only robust but also directly translatable in the analytical models used in the study. 3. results according to the pu-loop technique shown in fig. 3, the value of c equals (20±0.25 m/s). data appearing in this figure represent the measurements collected 25 cm downstream of the main tube inlet. the linear portion in this loop indicates a period within the pulse cycle undisturbed by the presence of reflected waves. c can be calculated according to any two measurements of pressure and velocity in this linear portion, as demonstrated by the two red points. wisam s. hacham al-khwarizmi engineering journal, vol. 21, no. 3, p.p. 106-117 (2025) 112 fig. 3. pu-loop for measurements of p and v taken 25 cm downstream of the selected synthetic flexible tube inlet. the measurements displayed are limited to the segment where the effect of wave reflection is absent. table 1 presents the results of the tensile testing conducted on an isotropic rubber specimen with a thickness of 0.2 cm. the elasticity modulus for that tensile testing was 3.3 mpa. theoretically, according to equation (2), if water with a density of 1000 kg/m3 is forced through the main tube, the resulting pulse wave will travel at a speed of approximately 19.5 m/s within the lumen of the tube. during compliance testing, the static pressure difference (dp) during the compression stroke was 101.5±0.40 kpa, and the corresponding volume change (dv) was 12 ml of water, from an initial volume (vo) of 45 ml, as shown in fig. 3. accordingly, the wave pulse speed was 19.5±0.05 m/s using the bramwell–hill equation [27], assuming water with a density of 1000 kg/m3 flowing through the main tube. 4. discussion the value of c obtained through experiments (in vitro) using the pu-loop technique was verified, considering the elasticity and compliance of the wall of the main tube. the main tube was tested, applying tensile and compliance tests. rubber materials form the uniform synthetic tube, developed using a circular cross-sectional area along its length. the lumen wall of the main tube was assumed to be isotropic and had a uniform elastic modulus. the main tube was completely immersed in water of the transparent reservoir to increase the sensitivity and the response of the flow probe and eliminate the effects of the gravitational forces and the stresses that may be generated during the experiments as a result of its contact with the surface of the platform. this installation permitted the main tubes to expand and inflate in free mode. the effect of the hydrostatic pressure variations between the upper and lower surfaces of the main tube was neglected. table 1 illustrates a report on the modulus of elasticity value for the same test. the table clearly shows that the verification process involves using the experimental results of tensile testing to draw the relationship between the load applied and its corresponding extension. elasticity of the elastic tube lumen was tested using tension load frame of (instron high wycombe, uk) the machine, considering bluehill2 software. this approach elaborates the report of calculating the value of (e) for the tested specimens and draw the relationship between the load applied and the extension according to that load. estimating the modulus of elasticity enables calculating the value of c through the lumen of the rubber tube using the moens–korteweg equation. this equation expresses the relationship between the arterial wall distensibility and the wave pulse speed using its elastic modulus. moreover, the compliance of the main tube was tested under static pressure to verify the magnitude of the traveling wave pulse speed through the main tube. the compliance or the buffering function of the artery’s lumen is a critical physical parameter in the study of the cardiovascular system. this term denotes an increase in the volume of the artery’s lumen accompanied by an increase in its pressure. the compliance of the tube lumen is defined as the ratio of volume change to the change in applied pressure. fig. 2 illustrates the setup for compliance testing. the setup consists of an elastic tube required to test its elasticity, which was initially filled with a volume of water and the catheter that measures the pressure inside the tube during this testing. the tip of the catheter was positioned in the centreline and midpoint of the tube to ensure an optimal and suitable location for collecting pressure readings. the setup included a medical syringe and a haemostat valve as well. the syringe was used to inject the water inside the compliant rubber tube with equal intervals as step input. the haemostat valve was used to adjust the position of the catheter’s tip and to seal the setup to prevent leakage. the catheter functioned as a feedback or transducer element for this setting, ; it was connected to data acquisition through the pressure control unit by bnc cable, gained data transferred into labview as a volt signal and monitored through the computer screen. the results were almost identical in the case of compression and retraction procedures, as shown wisam s. hacham al-khwarizmi engineering journal, vol. 21, no. 3, p.p. 106-117 (2025) 113 in fig. 4. in the figure, the magnitude of c is equal to 19.5±0.05 m/s at the compression and retraction courses of the main tube to its initial volume. data are presented as the mean of three measurements, and the dashed line indicates the linear regression of data, described by the equation and correlation coefficient, r2 = 0.9922 for compression procedure and r2 = 0.9883 for retraction procedure. consequently, the two magnitudes of c in the compression and retraction procedures for the main tube are relatively identical. the procedure for the compression and retraction phases was designed to closely mimic physiological conditions. this complementary behaviour reinforced the results of the current testing. 5. limitations this study’s findings may be limited by the sample size or the specific characteristics of the tested arterial specimens or materials. variability in vessel geometry, composition and disease states may affect the generalisability of the results to broader populations or different anatomical sites. the experimental conditions for the pu-loop and mechanical testing methods may not fully emulate physiological in vivo conditions. for example, pre-stress, residual strains and viscoelastic characteristics of the arterial wall are crucial phenomena to be simulated in vitro because of their influence on c estimations. fig. 4. pressure–volume diagram for the selected synthetic elastic tube. upper and lower panels represent compression and retraction procedure’s data, respectively. the pu-loop method often relies on simplifying assumptions—such as neglecting wave reflections, assuming a uniform cross-sectional geometry or ignoring longitudinal motion. these assumptions can introduce systematic errors when compared with tensile or compliance-based mechanical tests. measurement noise, calibration errors and/or operator variability contribute to the pu-loop and mechanical testing methods. in the pu-loop approach, noise in the pressure or velocity signals can significantly affect the accuracy of c estimation. on the contrary, mechanical testing is susceptible to non-linearities, hysteresis and slippage during tensile loading. no universally accepted gold standard is available for measuring c in experimental setups. thus, direct comparisons between methods become difficult, given that each technique might inherently emphasise different biomechanical properties (e.g., dynamic vs. static stiffness). biological tissues such as arteries exhibit anisotropic and heterogeneous properties that may not be fully captured by either method. whilst tensile testing can better characterise anisotropy through different loading directions, pu-loop estimates may oversimplify these features by focusing on a single dynamic wave speed parameter. arteries often require preconditioning to reach a stable mechanical response. differences in preconditioning protocols, or the absence of such procedures, can influence compliance and tensile measurements, thereby affecting comparative results between pu-loop and mechanical approaches. pu-loop tests are inherently dynamic, reflecting wave propagation characteristics, whereas tensile and compliance tests typically determine quasistatic mechanical properties. this fundamental difference complicates direct comparisons and interpretations of mechanical behaviour complicated. both approaches may rely on specific models (e.g., moens–korteweg equation) or assumptions that might not fully account for the complexities of real arterial behaviour, especially in diseased or remodelled vessels. variations in the experience of the operators or interpretation of the data may cause bias in the comparison; for example, determining the foot of the wave in pu-loop testing or the linear part of the stress–strain curve in tensile testing. the flexible tubes used in this experiment are stiffer than in vivo lumens. nevertheless, the main objective was to validate the use of the pu-loop wisam s. hacham al-khwarizmi engineering journal, vol. 21, no. 3, p.p. 106-117 (2025) 114 method in calculating c that propagates in flexible tubes, considering tensile and compliance testing. despite these limitations, our study demonstrated excellent consistency in the outcomes of all techniques, supporting the ingenuity of the puloop method. finally, potential long-term effects of fatigue under cyclic pulsatile loading were not considered because the tests were conducted over short durations. evidently, long-term cyclic loading would affect the results. the problem and objective statements of our future article will be directed towards investigating material fatigue and hysteresis under long-term cyclic loading to more closely simulate in vivo physiological conditions. 6. conclusions the c within the main tube, calculated using the pu-loop method based on simultaneous measurements of velocity and pressure technique, was 20±0.25 m/s. this value closely matched the estimates derived from established theoretical models: 19.5±0.012 m/s using the moens– korteweg equation and 19.5±0.05 m/s via the bramwell–hill equation. furthermore, the results obtained from tensile testing and compliance measurements on the same synthetic vessel were in strong agreement with those from the pu-loop technique. these findings verify the use of the puloop method to calculate c in elastic synthetic vessels. the consistency of pulse wave velocity values across dynamic pu-loop and tensile and compliance approaches supports the pu-loop as a reliable, non-invasive alternative. finally, the comparative analysis presented here has revealed the effectiveness of the traditional (i.e., compliance and tension testing) and dynamic (pu-loop) techniques in modelling haemodynamic responses under controlled conditions. the results emphasise the relevance of accounting for pulse wave reflections and compliance impacts in the estimation of c, along with the associated numerical parameters. whilst these findings provide valuable insights, further studies are guaranteed to validate these results under more physiologically representative and in vivo circumstances. in particular, the use of anatomically realistic models and blood-analogue fluids will be crucial for enhancing the translational relevance of the approach. these future investigations will help bridge the gap between clinical applications and experimental simulations. references [1] laurent, s., cockcroft, j., van bortel, l., boutouyrie, p., giannattasio, c., hayoz, d., pannier, b., vlachopoulos, c., wilkinson, i. and struijker-boudier, h., 2006. expert consensus document on arterial stiffness: methodological issues and clinical applications. european heart journal, 27(21), pp.2588–2605. https://doi.org/10.1093/eurheartj/ehl254. 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[32] international organization for standardization, 1998. iso 9276-1: representation of results of particle size analysis–part1: graphical representation, geneva: iso. https://doi.org/10.1098/rspb.1922.0022 ( 2025) 106-117، صفحة 3، العدد21مجلة الخوارزمي الهندسية المجلد وسام سعدي خضير 117 سرعة مقابل اختبار الشد تقدير سرعة موجة النبضة: دراسة مقارنة لتقنية حلقة الضغط على األنابيب المرنة االصطناعية واالمتثال 3، وسام حامد الزبيدي2، فالح الزويد*1وسام سعدي خضير ، كلية هندسة الخوارزمي، جامعة بغداد، بغداد، العراقنكس قسم هندسة الميكاترو 1 مجموعة كلية ترافورد وستوكبورت، ستريتفورد، قسم البناء واالستدامة، مانشستر، المملكة المتحدة 2 كلية ويغان ولي، المملكة المتحدة 3 wisam@kecbu.uobaghdad.edu.iq*البريد االلكتروني: المستخلص ( هي متغير مهم في مجال ديناميكا الدم ودراسة خصائص الجهاز القلبي الوعائي. وهي مرتبطة ارتباًطا مباشًرا بمرونة تجويف cسرعة موجة النبض ) u( المستخدمة لحسابها. تستفيد هذه التقنية من الخطية بين p( والضغط ) uللقياسات المتزامنة للسرعة ) puالشريان وعكسيًا بمرونة تجويف الشريان. حلقة انقباض القلب، حيث ال توجد موجة خلفية منعكسة بسبب تشعبات الشرايين و/أو انسدادها. تم اختبار صحة طريقة حل pو المبكرة من puقة خالل الفترة c( لألنبوب المرن. يستخدم األخير لحساب eباستخدام اختبار الشد والمطاوعة. تم إجراء اختبار الشد باستخدام خلية تحميل، مع تقدير معامل مرونة يونغ ) النبض -وفقًا لمعادلة موينز أجرينا اختبار االمتثال تحت الضغط الساكن. تنبأت هذه العالقة بدورات -( vوالحجم ) pلتقدير العالقة بين -كورتويج. أثناء استُخدم التغير الضغط واالنكماش للتحقق من صحة االختبار، الذي ُطبّق على تجويف األنبوب المرن. وبالتالي، لحساب قابلية تمدد تجويف األنبوب المرن، هيل. على الرغم من القيود، مثل: حجم عينة العينات المختبرة؛ -يتوافق مع معادلة برامويل c، ومن ثّم فإن pفي حجم التجويف الداخلي الناتج عن التغير في الدموية؛ عد الخواص وعدم تجانس األوعية تباين القياس؛ إهمال تماًما؛ حساسية االختبارات بسبب ضوضاء التجريبية غير فسيولوجية م مراعاة الظروف قيمة فإن الحي، الجسم داخل التجاويف من صالبة أكثر اصطناعية مرنة أنابيب واستخدام الحقيقي؛ الشرايين لسلوك الكاملة ) cالتعقيدات cالمحسوبة ، كانت متوافقة مع القيم المكتسبة من الحسابات القائمة على اختبارات االمتثال والشد. وفقًا الختبارات االمتثال والشد، puالمحسوبة(، باستخدام تقنية حلقة متر/ثانية. ونتيجةً لذلك، 0.25±20، بلغت السرعة puمتر/ثانية على التوالي، ووفقًا لتقنية حلقة 0.012.1±19.5متر/ثانية و 0.05±19.5بلغت السرعة cفي تقييم puتم التحقق من صحة منهجية حلقة mailto:wisam@kecbu.uobaghdad.edu.iq* this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 21, no. 1, march (2025), pp. 49-60 pvsyst and usingsolar power potential: an exploration s’baghdad khwarizmi college of engineering-at alcope shelio reem omar mahdi1, wisam s. hacham2* baghdad, khwarizmi college of engineering, university of baghdad,-al chatronics engineering,department of me 1,2 iraq *corresponding author, s email: wisam@kecbu.uobaghdad.edu.iq (received 21 september 2023; revised 24 february 2024; accepted 29 april 2024; published 1 march 2025) https://doi.org/10.22153/kej.2025.04.010 abstract the energy business has grown explosively over the past few decades because of increased global energy consumption, which has had catastrophic effects on the environment. as a result, the entire planet has begun transitioning to green energy generation, which has zero negative effects on the natural world. solar electricity has the highest efficiency amongst all forms of renewable energy. this study examines the monthly grid performance of a hypothetical 100 mwp solar facility linked to the al-khwarizmi college of engineering system. meteonorm 8.0 data are utilised in the simulation, which is run in pvsyst 7.2 and helioscope software. maximum energy production is the goal of the simulation, which is implemented at a constant tilt angle throughout the year. the building’s latitude is used to set the best angles or an east–west angle that is fixed 10 degrees to the south azimuth. the 3d display in helioscope allows for a natural, insightful design process, enabling the selection of highly effective design options and the analysis of shading and panel orientation effects. the use of helioscope and pvsyst software can provide insights into the amount of energy production from solar panels in a specific area. in this work, the amounts of energy generated using pvsyst and helioscope are 1,500.303 and 849.7653 mwh/year, respectively. keywords: helioscope software; pvsyst software; performance ratio; solar energy 1. introduction electricity is essential in our daily lives. at present, thermal and hydroelectric power plants generate the majority of electricity. however, renewable energy sources, such as solar and wind power, are becoming increasingly important because of concerns about greenhouse gas emissions and other environmental issues. numerous nations have established new energy laws that encourage the use of renewable energy sources in the power sector to lower greenhouse gas emissions [1]. renewable types of energy, especially solar energy, have increased rapidly in recent years and have become an important source of power generation in developed and developing countries. solar power holds promise because it rapidly expands and provides effective electricity sourced directly from the sun. as energy demands continue to rise, the need to generate electricity by using various energy sources becomes pressing. with advancements in technology and decreasing costs, solar energy is projected to become a feasible option soon. solar energy has an advantage over other power sources because it directly transforms sunlight into electricity through solar photovoltaic (pv) cells. solar power systems are categorised into three types: grid connected, off grid and hybrid systems [1]. grid-connected pv systems are currently the most common amongst all types. they are linked to a network, typically a public power grid, and supply surplus electricity. these technologies can mailto:wisam@kecbu.uobaghdad.edu.iq https://doi.org/10.22153/kej.2025.04.010 reem omar mahdi al-khwarizmi engineering journal, vol. 21, no.1, pp. 4960 (2025) 50 be employed in decentralised and centralised systems [2]. many studies have been conducted on solar pv systems to improve the study of solar pv systems, such as that at al-khwarizmi college of engineering (akcoe). ranvijay singh meena and savrabh mishra (2012) described the direct conversion of radiation from a heat source into electrical energy utilising pv cells. the study provided new opportunities for producing environmentally friendly electricity and demonstrated enhanced waste heat energy utilisation [3]. khadiza umme tahera, raisa fabiha and md. ziaur rahman khan (2018) investigated the design of a grid-connected solar pv system for a residence hall at buet. they calculated the load rooftop area to determine the system size and analysed the system to reduce its reliance on grid power. this solar pv system was modelled after their project [4]. in 2013, v. tyagi, nurul a. rahim, n. rahim, jeyraj a. and l. selvaraj showed how solar cells’ commercial efficiency can be increased. monocrystalline silicon’s efficiency increased from 15% in the 1950s to 17% in the 1970s. at present, its efficiency has increased by up to 28%. this study comprehensively examined the development of solar pv technologies and analysed their effectiveness, performance and cost [5]. mohammad al-najideen and saad s. alrwashdeh investigated the design of a solar pv system to satisfy the electricity needs of the engineering department of mu’tah university in jordan. a grid-connected solar pv system with more than 50 kw of power can considerably reduce energy costs by lowering the production and consumption of electricity [6]. the foundation and use of pv solar energy were outlined by reinders, verlinden, sark and freundlich (2017). in chapters 1 and 2 of their book, they discussed the fundamental processes of photovoltaics and provided a broad introduction to semiconductor materials and solar cell-related subjects. the application of pv technologies is the focus of the book’s second half. pv technologies that are used in space are thoroughly discussed in chapter 9, and pv modules and their manufacturing procedures are presented in chapter 10. pv technology applications in systems, buildings and other areas are highlighted in chapter 11 [7]. mohammed w. alhazmi, yousef samkari, mowffaq oreijah and ahmed alnoosani (2018) employed a solar pv system to minimise umm alqura university’s 100 mw power consumption [8]. this study proposes the installation of a solar pv system at akcoe, recognising the pivotal role that energy plays in the progress of civilisation. solar energy has elicited much attention as a means to enhance efficiency, mitigate power consumption, curtail carbon emissions and diminish the reliance on fossil fuels. the novelty of this research lies in its focus on integrating the akcoe system with a theoretical 100 mwp solar project to enable a comprehensive examination of the facility’s monthly grid performance. 2. geographical location of the site akcoe is a building with five different departments, and it is situated at the university of baghdad in the heart of baghdad province. it is located at longitude 44.3792° e and latitude 33.2723° n. its temperature ranges from 26 °c to 44 °c in summer and is as low as 10 °c in winter [9]. therefore, another type of energy, aside from that from fossil fuel, must be used to produce energy. given that the location of the site and the sun are very high in summer and winter, this site is ideal for setting up the pv power plant for our study. 3. meteonorm data the yearly and monthly climate data used in this project are shown in table 1. the data are derived using information from meteonorm 8.0. the table displays the meteorological information and incident energy for the pv system. the worldwide horizontal irradiation (globhor) is 1,817 kwh/m2/year, the horizontal diffuse irradiation (diffhor) is 857.5 kwh/m2 and the overall global incident energy on the collector plane is 2,564.7 kwh/m2. reem omar mahdi al-khwarizmi engineering journal, vol. 21, no.1, pp. 4960 (2025) 51 table 1, information on meteorological conditions and incident energy month globhor kwh/m² diffhor kwh/m² t_amb °c windvel m/s globinc kwh/m² difsinc kwh/m² alb_inc kwh/m² difs_gi ratio january 94.4 37.9 7.46 1.6 181.0 20.89 4.866 0.00 february 104.8 50.3 10.33 2 166.1 27.23 4.489 0.0 march 146.2 72.6 15.14 2.2 207.8 39.34 4.752 0.0 april 177.2 89.3 19.69 2.2 229.1 45.35 4.214 0.0 may 197.2 102.5 25.76 2.2 239.7 50.98 3.985 0.0 june 219.7 97.2 30.73 2.4 274.2 44.07 4.377 0.0 july 212.2 99.3 34.03 2.5 264.2 46.71 4.276 0.0 august 191.5 94.6 33.50 2.1 241.7 47.03 4.242 0.0 september 167.0 68.9 28.49 1.8 241.5 35.14 4.803 0.0 october 127.3 63.0 23.13 1.6 189.4 33.84 4.926 0.0 november 95.7 44.5 13.96 1.4 169.5 24.41 4.718 0.0 december 83.8 37.2 9.14 1.5 160.4 20.46 4.539 0.0 year 1,817.0 857.5 21.01 2.0 2,564.7 435.46 54.186 0.0 4. system layout the projected plant can generate 100 mwp of electricity in its current form. a solar power plant requires a solar pv module, inverter, mounting structure and cables, meters, switches, fuses and other components. batteries are not utilised because the solar power plant is linked to the grid. sixteen modules are used in the system layout, and when they are coupled in sequence, they create 87 strings. we employ east–west dual-axis tracking, which is constant depending on the position of the building; thus, the tilt angle of the pv array is maintained at 10° n to receive the largest amount of solar energy possible. the system’s grid connection is shown in figure 1. fig. 1. grid connection of the system 5. performance indicators for solar power plants 5.1 array yield array yield is sometimes referred to as matrix efficiency and is determined using the nominal power (kwh/kwp/day) and daily dc output energy. the ratio of a pv array’s daily, monthly or annual dc energy production to its rated power is known as the array yield [10]. ya = edc po …(1) 5.2 reference system yield the best array yield determined by nominal power (pnom) with no loss is called the reference system yield. the reference radiation under a standard temperature condition (stc) is set to 1,000 w/m2 because each incident kwh should ideally provide the array pnom for one hour. the available radiation is theoretically normalised to the reference radiation by the incidence energy on the array plane, which is mathematically equivalent to yr. site location, weather and solar pv panel orientation are all important factors [11]. yr = ht(kwh/m2) ia(kw/m2) … (2) 5.3 final system yield the peak power or installed kwp of a pv array at stc divided by the ac energy production of a solar pv system on an annual, monthly or daily basis is known as the ultimate system yield. this yield shows how long a solar pv system must operate at rated power to produce net energy. it is reem omar mahdi al-khwarizmi engineering journal, vol. 21, no.1, pp. 4960 (2025) 52 the energy output of the system adjusted for system size. the ultimate yield measures the performance of the solar pv system in terms of the solar radiation resource [12]. yf = eac pp … (3) 5.4 pv module efficiency the efficiency of a pv module may be calculated as [13] ɳpv = edc gi∗apv × 100%. … (4) 5.5 efficiency of inverters inverter efficiency is defined as the ratio of the inverter’s ac power to the pv array system’s dc power. ref. [14] provided instant inverter efficiency as follows: ɳinv = pac pdc × 100%. … (5) 5.6 pv system efficiency the energy generated by a pv array is divided by the entire in-plane solar insolation to determine the overall pv system conversion efficiency, as shown in ref. [14]. ɳs = eac gi∗apv × 100% …(6) the performance of a solar pv plant is influenced by loss characteristics. a solar pv system might lose almost any component that was utilised in its construction. calculating capture losses is one way to assess the multiple losses in a solar pv plant. capture losses consist of heat losses. the temperature of the pv module and the loss caused by fluctuating radiation, dust buildup and other elements determine capture losses. losses in the dc and ac lines are included in the system losses. 5.7 array capture loss array capture loss is the difference between the array and reference yields. this loss mostly affects solar arrays and is caused by various factors, such as rising pv cell temperatures, partial shadowing and dust building in photovoltaic arrays, maximum power point errors and mismatches. another term for it is collection loss [15]. la = yr − ya … (7) 5.8 system loss system loss is the variation between system and array yields. examples include battery inefficiencies in standalone systems and inverter losses in grid-connected systems [16]. ls = ya − yf … (8) 6. methodology in this study, the solar energy generation potential of placing pv panels on the roofs of college buildings was calculated using pvsyst and helioscope. the optimal panel position was determined with the helioscope algorithm. we began by specifying the longitude and latitude coordinates of the desired site. the software acquired meteorological data from meteonorm, a global provider of historical, current and forecasted climate data. for its efforts in solar energy, renewable energy, urban planning, architecture and environmental impact assessments, meteonorm has received much appreciation [15]. the tilt and azimuth angles were chosen to specify the panels’ orientation. tilt angle is the degree of inclination of a solar panel or pv module concerning a horizontal surface. this setting has a considerable influence on the panel’s ability to capture energy. given that the tilt angle affects the quantity of sunshine the panels receive throughout the year, it is crucial in optimising the energy production of a solar system. solar installations employ many types of tilt angles, but inclination angle tracking is often used. tilt angle tracking involves solar tracking systems that continually alter the inclination of solar panels during the day to face the sun directly. solar tracking systems are classified into two types. a. single-axis tracking: during the day, panels are adjusted along one axis (either horizontally or vertically) to track the sun’s east–west movement. this tracking method is simpler and less costly than dual-axis tracking, but it provides less exact solar tracking. b. dual-axis tracking: panels are adjusted along horizontal and vertical axes, allowing them to track the movement of the sun in azimuth (east– west) and elevation (up–down) directions. dualaxis tracking systems are sophisticated and expensive, but they catch and use the most solar energy. tilt angle tracking is more expensive to install and need more maintenance than permanent or seasonal tilt systems, even though they may substantially increase the energy output. the reem omar mahdi al-khwarizmi engineering journal, vol. 21, no.1, pp. 4960 (2025) 53 location of the installation, the available budget, the amount of energy required, the desired degree of solar energy collection and the efficiency of the system influence the tilt angle that is employed. however, we found that the best method to maximise the tilt angle in the setting of our research, which focuses on public places, is east– west tracking. the solar panels’ orientation with respect to the cardinal directions is known as the east–west angle. in this instance, the panels are slightly slanted east of due south after being fixed 10° to the south azimuth. this angle was chosen in this study for the following reasons: 1. maximising daily energy production: tilting the panels slightly to the east allows for early sun exposure in the morning. this situation implies that the generation of energy starts at a certain time in the day, allowing the solar panels to harness sunlight, especially in the morning when the sun is positioned low in the sky. 2. evening energy generation: although angling towards the east may result in a decrease in captured energy at midday when the sun is at its highest position, it helps prolong energy generation into the late afternoon. this situation could be advantageous for fulfilling energy needs in the day. the choice of an east–west orientation, such as a fixed tilt angle, serves as a balance to enhance the energy output all year round. this setup ensures energy production throughout the day and across seasons, thus offering benefits for grid integration and effective load management. in summary, the decision to maintain a consistent tilt angle all year round and a set east– west angle southward is based on practicality and the goal of balancing energy generation throughout the times of the day and seasons. these selections can be tailored to suit locations and energy generation objectives, with the overarching aim of optimising the operation and cost efficiency of the solar pv system. the azimuth angle refers to the angle between the direction of the true south and the tilt angle of the solar panel. the solar cell must face true south to capture the most sunlight. as a result, an azimuth angle of (0) corresponds to the ideal orientation, which is directly facing south. fig. 2. sun path at akcoe figure 2 depicts the sun’s path in baghdad throughout the year and the related solar radiation levels. it shows that the longest day is june 22, with 15 hours of sunshine and just 9 hours of darkness. the shortest day is december 22, with 10 hours of sunshine and 14 hours of darkness. this difference is caused by the sun’s high position in summer and its low position in winter. next, we selected the components of our system. we had the option of selecting either the required power output or the application area. pvsyst and helioscope provide vast databases covering numerous types of solar panels and inverters from various manufacturers, allowing us to pick the most appropriate ones. we chose ginko solar company’s solar panels for this project because they are known for their high quality and efficiency. under stc, these panels have a maximum power capacity of 610 wp and a maximum power voltage (vmp) of 45.25 v, with a module efficiency of 21.46% [18]. an inverter is needed to convert dc from solar panels to ac. to complete our arrangement, we selected an sma company inverter with a nominal pv power of 100 kw and a maximum efficiency of 98.80% [19]. figures 3 and 4 illustrate all of the details and the shading effects. reem omar mahdi al-khwarizmi engineering journal, vol. 21, no.1, pp. 4960 (2025) 54 fig. 3. implementation of rooftop solar panels and assessement of their susceptibility to shading through helioscope software fig. 4. examination of the building’s views, with the left part capturing the southeastern perspective and the right part depicting the southwestern outlook. such examination is facilitated by helioscope software 7. results 7.1 pvsyst software the proposed pv system’s simulation results were analysed. the project’s needs and limitations are reflected in pvsyst, where the system’s production of 100 mw/month using monocrystalline solar cells is displayed. produced energy, specific production and performance ratio were the key production factors in this simulation. the findings were used to assess the monocrystalline pv system’s performance. 7.1.1 mostly generated energy table 2 displays the balances and important results of a grid-connected pv system. the yearly average horizontal irradiance for the entire planet is 1,817 kwh/m². the yearly incident energy of the collecting plane is 2,564.7 kwh/m².h. in june, 141,343 kwh was the largest amount of energy injected into the system. in december, 102,481 kwh was the least amount of energy introduced into the system. annually, 1,500,303 kwh of energy is injected into the grid. the outdoor temperature is 21.01 °c on the average. two parameters were evaluated based on the primary simulation findings. the first parameter was the total quantity of energy generated every year by the system of monocrystalline solar panels, which is referred to as produced energy (1,500,303 kwh/year). the average performance ratio (pr), which is the second parameter, for the year is 86.86%. reem omar mahdi al-khwarizmi engineering journal, vol. 21, no.1, pp. 4960 (2025) 55 table 2, balances and main results month globhor kwh/m² diffhor kwh/m² t_amb °c globinc kwh/m² globeff kwh/m² earray kwh/m² e_grid kwh pr ratio january 94.4 37.9 7.46 181.0 144.3 116,402 114,511 0.923 february 104.8 50.3 10.33 166.1 137.4 109,629 107,859 0.911 march 146.2 72.6 15.14 207.8 167.6 131,071 128,977 0.890 april 177.2 89.3 19.69 229.1 180.6 138,824 136,628 0.874 may 197.2 102.5 25.76 239.7 182.7 137,626 135,509 0.854 june 219.7 97.2 30.73 274.2 194.8 143,519 141,343 0.834 july 212.2 99.3 34.03 264.2 192.1 140,200 138,110 0.827 august 191.5 94.6 33.50 241.7 187.7 137,044 135,003 0.830 september 167.0 68.9 28.49 241.5 186.1 137,634 135,526 0.842 october 127.3 63.0 23.13 189.4 157.5 119,692 117,860 0.868 november 95.7 44.5 13.96 169.5 136.9 108,190 106,496 0.903 december 83.8 37.2 9.14 160.4 129.4 104,151 102,481 0.921 year 1,817.0 857.5 21.01 2,564.7 1,997.1 1,523,983 1,500,303 0.869 note: globhoris is horizontal global irradiation, diffhor is horizontal diffuse irradiation, t_amb is ambient temperature, glob inc is the global energy incident on the plane, globeff is the effective global energy corresponding to iam and shadings, earray is the effective energy at the output of the array; e_grid is the energy injected into the grid and pr is the performance ratio. 7.1.2 pr a pv plant’s quality is evaluated using pr, a quality factor. pr illustrates the relationship between the theoretical and actual energy production of pv installation. after accounting for energy losses and consumption, pr displays the amount of energy. the losses include damage to the solar panel, loss of the inclination angle, damage from dust, damage from shadows and damage from changes in module temperature. pr is often around 80% because of inevitable operational losses. if pr reaches 80%, the technique will become increasingly effective and successful. on an annual basis, pr is used to assess how well solar power plants operate. figure 5 displays the incident energy pr for each month of the year. pr is 0.869 on the average. fig. 5. performance ratio (%) 7.1.3 normalised production figure 6 depicts the normalised output of pv power facilities. it shows pv array collection losses, system losses and usable energy generated by inverter output. it also indicates the monthly output and kwh losses. fig. 6. monthly nominal power graph reem omar mahdi al-khwarizmi engineering journal, vol. 21, no.1, pp. 4960 (2025) 56 figure 6 shows that the annual average daily energy output (𝑌𝐹) is 6.11 kwh, the collection loss (𝐿𝑐) is 0.83 kwh and the system or inverter loss (𝐿𝑠) is 0.09 kwh. 7.1.4 system losses the specific monthly average system losses are displayed in kwh in table 3. the yearly module quality loss (mod qual) is 8,803.34 kwh. the mismatch loss (mis loss) per module each year is 25,426 kwh. the ohmic wiring loss (ohm loss) for a year is 13,846 kwh. the virtual energy of the array at the maximum power point (mpp) is known as earrmpp. the inverter loss for the entire year is 21,103 kwh. table 3, detailed system losses month mod qual kwh mis loss kwh ohm loss kwh earrmpp kwh invloss kwh january −656.680 1,897 973 85,345 1,327 february −596.769 1,724 855 77,587 1,182 march −732.644 2,116 1,089 95,213 1,425 april −794.561 2,295 1,238 103,203 1,544 may −811.558 2,344 1,288 105,387 1,762 june −908.879 2,625 1,579 117,889 2,686 july −867.306 2,505 1,467 112,536 2,976 august −796.124 2,299 1,310 103,337 2,507 september −807.814 2,333 1,380 104,803 2,051 october −648.924 1,874 975 84,323 1,307 november −602.420 1,740 866 78,320 1,172 december −579.666 1,675 826 75,368 1,163 year −8,803.345 25,426 13,846 1,143,311 21,103 the total system loss diagram for the akcoe site is shown in figure 7. the worldwide horizontal irradiation is 1,817 kwh/m². the effective irradiation on the collecting plane is 1,997 kwh/m². the pv cell converts the solar energy into electrical energy. the nominal energy of the array after pv conversion is 1,696,963 kwh. under (stc, the pv array’s efficiency is 21.84%. the virtual energy received from the array is 1,523,653 kwh. in the inverter output, the available energy after inverter failure is 1,500,303 kwh. fig. 7. sources of system loss in pvsyst software reem omar mahdi al-khwarizmi engineering journal, vol. 21, no.1, pp. 4960 (2025) 57 7.2 helioscope software 7.2.1 energy generated in the system figure 8 depicts the energy-generating ranges in the helioscope software system. helioscope software systems have an average annual ambient temperature of 24.4 °c. helioscope, a modelling tool, generates 849,765.3 kwh on the average per year. table 4 displays grid energy, panel energy, plan of array (poa), shaded irradiance and global horizontal irradiance (ghi). ghi, which is the total amount of light that a square meter on the ground receives, is measured in this case. the solar irradiance used in poa is a combination of albedo (irradiation reflected by the earth) and diffuse irradiance. the direct irradiance on a panel or poa is solar irradiation multiplied by the cosine of the angle of incidence (the angle between the sun’s direction and a panel-normal vector). fig. 8. monthly energy prediction using helioscope software table 4, monthly prediction using helioscope software month ghi (kwh/𝐦𝟐) poa (kwh/𝐦𝟐) shaded (kwh/𝐦𝟐) nameplate (kwh) grid (kwh) january 92.8 92.6 91.7 45,100.7 41,640.1 february 112.9 112.9 111.5 55,451.1 50,735.1 march 157.0 156.4 154.9 77,704.7 69,706.2 april 180.6 197.7 178.3 89,771.0 79,645.1 may 221.3 220.2 218.6 110,507.8 95,683.0 june 236.8 235.7 233.5 118,340.9 100,399.4 july 234.7 233.6 231.7 117,330.7 98,715.1 august 218.3 217.1 215.7 109,038.3 91,689.7 september 179.8 179.2 177.4 89,321.6 76,340.6 october 144.9 144.3 143.3 71,545.4 62,534.5 november 103.5 103.2 102.1 50,389.0 45,450.4 december 84.0 83.8 82.8 40,591.1 37,226.1 akcoe’s flat roof has certain trammels, such as a cooling room and a water container, because the area of the roof is close to 5,508 m2. the structure can only accommodate 870 solar panels; thus, we chose 610 w panels. the total energy produced by these panels is 849,765.3 kwh. 7.2.2 system losses many losses occurred during the installation and operation of the system. figure 9 depicts various losses, such as ac system losses (losses after inverters) and soiling losses (losses caused by contaminants, such as dust). fig. 9. sources of system loss in helioscope software reem omar mahdi al-khwarizmi engineering journal, vol. 21, no.1, pp. 4960 (2025) 58 the actual energy spent in akcoe is 935,470.295 kwh, and the energy produced by the pv system is nearly 1,500,303 kwh/year. hence, it is useful to employ the pv system instead of electricity from the burning of fossil fuel. 8. discussion using pvsyst and helioscope software in a project allows for a full, detailed evaluation of pv system performance and design. these software programs are useful tools in the solar energy business because they help increase the efficiency and production of solar power plants. pvsyst is a well-known reliable software that allows users to model and simulate pv systems. it offers detailed information on solar irradiance, shading, system losses and energy output estimates via a number of functions. to use pvsyst for a project, customers must provide the geographical location of the project, pv module characteristics, pv array orientation and inclination. pvsyst also uses weather data from meteonorm to provide a realistic simulation of system performance over time. analysing the energy output and system losses allows for adjustments to pv system design to increase energy generation and overall efficiency. helioscope is a software tool that is beneficial for developing and improving pv system architectures. it offers 3d modelling and visualisation tools to help determine the effect of shade and panel orientation on energy generation. helioscope allows users to easily determine the best design for pv panels by specifying the location, tilt and azimuth angles. this tool also enables users to compare different array installation alternatives, such as rooftop or ground-mounted arrays, while considering factors, such as sun-path and shading diagrams. in the design of a pv system, pvsyst and helioscope must be utilised. pvsyst allows users to accurately predict the energy output on the basis of weather and system conditions. meanwhile, helioscope aids in the design phase by determining the effects of panel placement and shading. these software packages allow users to identify design flaws and improve architecture for maximum energy production and efficiency. furthermore, these software packages have simulation tools that enable project teams to perform sensitivity analyses, which allow them to assess the effects of different factors on system performance. for example, changes made to the panel type, inverter selection or system orientation may be examined quickly. this procedure provides vital insights into the most cost-effective and efficient combinations. in summary, the use of pvsyst and helioscope in projects provides designers and developers with the knowledge they need to make educated decisions, optimise pv system layouts and achieve high energy output and roi. these software tools are crucial for solar project design and implementation and assist in the progress and broad usage of renewable energy technology. 9. conclusions energy yield analysis for 1,500 mw of pv power was conducted using pvsyst modelling software. the geographical location of baghdad university, which is situated at 33.2723° n and 44.3792° e, was used for solar power generation. around 87% of pr was attributed to performance, and 1,500 mw of power was produced. it was possible to create as much electricity by installing roughly 100 mw each month. this study discussed the technical and financial viability of a grid-connected 100 mw solar pv energyproducing plant at the university of baghdad as well as design modelling and simulation. the monocrystalline pv system’s average pr in the simulation of the planned site was 87%. this system accounted for almost 90% of the overall power use in akcoe at the university of baghdad. helioscope provided us a 3d representation of the layout of our pv system, thereby allowing us to evaluate the effects of shading and panel orientation. by exploring location options, such as rooftop and ground installations, we obtained insights into optimal design choices. the userfriendly interface and advanced visualisation tools of helioscope enabled us to engage in an insightful design process. overall, the incorporation of pvsyst and helioscope into our project improved the precision and efficacy of our design process and deepened our understanding of solar energy technology. we were able to create a highperformance, well-optimised solar energy system by using the capabilities of these software tools, thus contributing to a clean, sustainable future. the usage of these tools increased the success of our specific project. these results highlight the need for cutting-edge simulation and modelling reem omar mahdi al-khwarizmi engineering journal, vol. 21, no.1, pp. 4960 (2025) 59 software in the development of renewable energy technologies. references [1] solar energy, online available: 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[14] boonmee, chaiyant, boonyang plangklang, and napat watjanatepin. (2009) "system performance of a three-phase pv-gridconnected system installed in thailand: data monitored analysis." renewable energy. [15] adaramola, muyiwa s., and emil et vågnes. (2015) "preliminary assessment of a small-scale rooftop pv-grid tied in norwegian climatic conditions." energy conversion and management. [16] ayompe, l. m., et al. (2011) "measured performance of a 1.72 kw rooftop gridconnected photovoltaic system in ireland." energy conversion and management. [17] meteonorm version 8 available online: https://meteonorm.com/en/meteonormversion-8 [18] solar panel datasheet of ginko solar panels with a maximum power capacity of 610 wp. [19] inverter datasheet of sma company inverter with a nominal pv power of 100kw. https://www.seia.org/initiatives/about-solar-energy https://www.seia.org/initiatives/about-solar-energy https://www.climatestotravel.com/climate/iraq#baghdad https://www.climatestotravel.com/climate/iraq#baghdad https://meteonorm.com/en/meteonorm-version-8 https://meteonorm.com/en/meteonorm-version-8 (2025) 49-60، صفحة 1، العدد21مجلة الخوارزمي الهندسية المجلد ريم عمر مهدي 60 ي ف helioscopeو pvsystبرنامج إمكانات الطاقة الشمسية في بغداد: استكشاف باستخدام كلية الهندسة الخوارزمي ريم عمر مهدي1 ، وسام سعدي خضير2* 2،1 قسم هندسة الميكاترونكس، كلية الهندسة الخوارزمي، جامعة بغداد، بغداد، العراق wisam@kecbu.uobaghdad.edu.iqالبريد االلكتروني:* المستخلص قب وخيمة على مدى العقود القليلة الماضية، أدى ارتفاع الطلب العالمي على الطاقة إلى نشوء نمو هائل في قطاع الطاقة، وما ترتب على ذلك من عوا يعي. تتمتع الكهرباء على البيئة. ونتيجة لذلك، بدأ الكوكب بأكمله في التحول إلى توليد الطاقة الخضراء، والتي ليس لها أي آثار سلبية على العالم الطب ميجاوات 100قدرة الشمسية بأعلى كفاءة مقارنة بأشكال الطاقة المتجددة األخرى. تتناول هذه الدراسة أداء الشبكة الشهرية لمنشأة طاقة شمسية افتراضية ب وبرنامج pvsyst 7.2 يلها في برنامجفي المحاكاة التي يتم تشغ meteonorm 8.0 مرتبطة بنظام كلية الخوارزمي للهندسة. يتم استخدام بيانات . heliscope إن الحد األقصى إلنتاج الطاقة هو هدف المحاكاة، والتي يتم تشغيلها بزاوية ميل ثابتة على مدار العام. يتم استخدام خط عرض المبنى مت الجنوبي. ومع ذلك، فإن العرض ثالثي األبعاد فيدرجات إلى الس 10لتحديد أفضل الزوايا أو الزاوية الشرقية والغربية والتي تكون ثابتة بمقدار helioscopeحة. سمح بعملية تصميم أكثر طبيعية وثاقبة، مما أدى بدوره إلى اختيار خيارات التصميم األكثر فعالية وتحليل تأثيرات التظليل واتجاه اللو .ؤية مستقبلية لكمية إنتاج الطاقة من األلواح الشمسية في منطقة معينةفي الحصول على ر pvsyst و heliscope وأخيًرا، سيساعدنا استخدام برنامجي mailto:wisam@kecbu.uobaghdad.edu.iq baghdad’s solar power potential: an exploration using pvsyst and helioscope at al-khwarizmi college of engineering reem omar mahdi1, wisam s. hacham2* 1,2 department of mechatronics engineering, al-khwarizmi college of engineering, university of baghdad, baghdad, iraq *corresponding author, s email: wisam@kecbu.uobaghdad.edu.iq abstract the energy business has grown explosively over the past few decades because of increased global energy consumption, which has had catastrophic effects on the environment. as a result, the entire planet has begun transitioning to green energy gen... المستخلص this is an open access article under the cc by license : al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 21, no. 3, sptember, (2025), pp. 3547 internet of things software-defined network intrusion detection dataset: interand intra-domain heba dhirar1*, and ali h. hamad2 1,2 department of information and communication engineering, al-khwarizmi college of engineering, university of baghdad, baghdad, iraq *corresponding author’s email: heba.d@kecbu.uobaghdad.edu.iq (received 17 january 2024; revised 20 may 2024; accepted 28 august 2024; published 1september 2025) https://doi.org/10.22153/kej.2025.08.001 abstract software-defined networks (sdns) are extensively deployed in many network configurations. however, the development of new technology presents several vulnerabilities and risks that continue to pose challenges for manufacturers in addressing them. one of the primary obstacles encountered in deploying an intrusion detection system (ids) is the absence of an openly accessible dataset, especially one obtained from sdn and sdn-based internet of things (iot) networks. this work produces a comprehensive dataset to evaluate the effectiveness of anomaly-based idss in detecting interand intradomain attacks. the dataset comprises 86 features extracted from approximately 40 million records obtained from simulated sdn-based iot networks captured within two flow profiles representing normal and 15 different attack types. in addition, the evaluation is demonstrated by employing six widely used machine learning and deep learning approaches for idss: decision tree classifiers, random forest classifiers, deep neural networks, k-nearest neighbours, bernoulli naive bayes, and logistic regression. keywords: dataset; intrusion detection system (ids); internet of things (iot); software-defined network (sdn); threat; attack vector; network intrusion dataset. 1. introduction the increasing number of personal devices and internet-enabled technology has led to increased complexity in computer networks. furthermore, the increased adoption of cloud services has resulted in an unusual expansion of private and public cloud services. in such contexts, the implementation of effective management and the prevention of configuration errors present significant challenges. whilst the internet of things (iot) enables the connection and exchange of data amongst a multitude of devices [1,2], increasing iot advancement contributes to the complexity of this issue [3]. this concern is addressed by implementing software-defined network (sdn) technology to transform network architecture and operations. sdns facilitate the development of network services by using software applications and open application programming interfaces under centralised supervision. the approach centralises administration by abstracting the control plane from the data-forwarding function [4]. the use of centralised management can effectively simplify network administration processes and reduce the occurrence of configuration errors. in practical implementation, sdn continues to face numerous security challenges, such as the presence of insider threats. these threats involve the exploitation of internal devices by unauthorised individuals to launch attacks on other devices within the network, including the central controller. security measures are improved by implementing an intrusion detection system (ids) in every node to assist in detecting and identifying potentially harmful nodes. in the context of idss, two primary approaches are commonly utilised: signature-based and anomaly-based. the signature-based approach mailto:heba.d@kecbu.uobaghdad.edu.iq https://doi.org/10.22153/kej.2025.08.001 heba dhirar al-khwarizmi engineering journal, vol. 21, no.3, pp. 3547 (2025) 36 is frequently utilised in retail items, which can be attributed to its notable efficacy in detecting known threats and its ability to minimise false positives. however, this method falls short of identifying newer or unfamiliar network attacks that occur daily. however, anomaly-based detection systems have garnered significant interest from researchers in the academic community because of their capacity to identify previously unknown threats. the absence of publicly available datasets, specifically those derived from sdns, is a significant obstacle to the deployment of idss. this challenge needs to be addressed, and researchers, industry stakeholders and regulatory agencies need to work together and create standardised datasets that adequately represent the complexities of modern network systems [5]. the primary objective of this work is to provide a dataset that encompasses the key attributes necessary for the identification of attacks and the assessment of anomaly-based idss in the context of sdn-based iot environments. the work consists of two distinct parts: the initial module gathers traffic statistics to generate the dataset, whereas the subsequent module employs a method based on machine learning (ml) and deep learning (dl) to evaluate the generated dataset. the proposed dataset involves the inclusion of a diverse range of attacks, the implementation of a multidomain attack scenario and the utilisation of realistic traffic traces. interdomain refers to an attack that occurs between distinct systems or entities. these attacks usually entail a criminal focusing on a system, network or organisation that is distinct from their own and an intra-attack, which refers to an attack that occurs within the same system or entity. these attacks involve malicious actions conducted by people or collectives who already possess entry to the system or organisation being targeted. the contributions of this research can be summarised as follows: • the advantages of the current ids, sdn and iot datasets were analysed. • two traffic profiles, namely, the normal profile and the attack profile, were used. • a total of 15 attack types were considered for two scenarios, namely, interdomain attack and intraattack. • the dataset was empirically evaluated via ml and dl methodologies. the paper is structured as follows: section 2 presents a comprehensive review of the relevant literature. section 3 briefly examines the various attack vectors that target sdn and iot networks. sections 4 and 5 describe the experimental strategy and its execution and the results. section 6 presents the conclusions drawn from the work. 2. related work this section presents a summary of the wellknown dataset that is most similar to the proposed dataset and has been used in the field of intrusion detection. bot–iot [6]: this dataset contains 46 features that include normal network traffic and six types of attack traffic: dos, ddos, keylogging, service scanning, os fingerprinting and data theft obtained from a simulated iot network. nevertheless, compared with others, the dataset is imbalanced, with certain attack types having many fewer entries. the data theft instances total 118, and keylogging instances total 1469, which cannot meet the requirements of the majority of ml algorithms. sdn–iot [7]: two datasets with topologies, characteristics and packet transmission rates comparable to those of the bot–iot dataset were generated. the distinguishing factor between the datasets lies in the number of simulated iot devices employed to evaluate the efficacy of attack detection models trained on these datasets. the datasets contain 33 extracted features from normal traffic and five attack types: ddos, dos, os fingerprinting, port scanning and fuzzing. these attacks were implemented with diverse targets and configurations. this dataset represents the initial instance of a publicly accessible intrusion detection dataset specifically designed for sdn in the context of the iot. insdn [8]: this dataset comprises an estimated number of flow-based features and covers a wide range of attack conditions. the authors used two profiles to generate normal and attack traffic patterns within a simulated sdn architecture. the dataset contains 83 packet properties that were collected from several common network attack types, such as botnets, dos, web attacks, ddos, password brute force attacks, probes and tool-based exploits. ddos–sdn [9]: this dataset contains 16 features obtained from the sdn to detect ddos attacks. a hybrid model was employed, combining the support vector classifier (svc) and random forest (rf) algorithms, for traffic classification. the initial classification was performed via the svc, and the results were subsequently filtered via the rf algorithm. the model was trained on the generated dataset and achieved an accuracy rate of 98.8%. ton–iot [10]: this dataset comprises a diverse range of regular and adversarial occurrences across several iots and industrial iot services. this dataset comprises data from heterogeneous sources, which were gathered through a test that accurately heba dhirar al-khwarizmi engineering journal, vol. 21, no.3, pp. 3547 (2025) 37 emulates an iot architecture facilitating communication between edge, fog and cloud stages. however, as neither sensor measurements nor iot network traffic is present in these datasets, they do not incorporate the unique properties of iot/iot applications, even though some researchers have evaluated their iot-related intrusion detection technologies. in addition, some datasets, such as kdd–cup 99 [11,12], nsl–kdd [13], iscx [14] and caida [15], have been specifically developed for conventional networks and extensively utilised in research related to idss for sdn. notably, the existing datasets available for analysis have not been specifically designed or generated within the context of an sdn environment. table 1 presents a comparative analysis between the previously mentioned dataset and the dataset proposed in this work. in this work, several tools were employed in conducting a range of attack scenarios, such as dos, ddos, brute force, prope, mirai, exploitation and botnet attacks. multiple attack scenarios have been established multiple times to address a range of attacks that target multiple hosts to encompass the interand intradomains. in addition, a range of widely used application services have been addressed, including http, dns, ftp, youtube, facebook and browsing. 3. attack vector the introduction of a centralised design within the context of sdn architecture brings forward potential vulnerabilities capable of compromising the functionality and security of an sdn susceptible to a range of security attacks. this section presents a review of several attack types and vectors. 3.1. sdn attack vectors various types of attacks can inevitably exploit vulnerabilities present in all layers of an sdn [16]. certain attacks are specifically targeted at sdn. these attacks have the potential to manifest within the sdn controller itself or via the communication routes connecting control and data plane devices. in addition, additional breaches are common in sdn standards and traditional networks. the perpetrator must increase their privileges or utilise the compromised workstation to initiate subsequent attacks on various devices or subnets [17]. table 1. comprehensive overview of ids datasets. dataset year attribute environment attacks types iot[6]-bot 2018 42 iot network dos, ddos, theft, and reconnaissance in addition to normal traffic data. iot[7]-sdn 2020 33 based iot-sdn ddos, dos, os fingerprinting, port scanning and fuzzing insdn[8] 2020 83 sdn network botnet, dos, ddos, brute-forcing, probe, web attacks, exploitation using various tools (ares, slowhttptest, loic, hulk, nping, torshammer, metasploit, sqlmap, hping3, hydra, burp suite, nmap). sdn[9]-ddos 2021 16 sdn network ddos iot[10]-ton 2021 44 iot network ddos, cross-site scripting, ransomware, injection, and backdoor in addition to normal traffic data using node-red. proposed dataset 2023 84 based iot-sdn botnet, brute-force, dos, ddos (icmp, syn, udp), exploitation, malware, mirai, probe, r2l, ur2, web-based, spoofing, recon using various tools in addition to normal traffic data. different mitigation strategies must be employed to address these challenges. the primary forms of attacks that target sdns can be categorised into four distinct types (fig. 1.a). data plane: intruders may target the network elements themselves with the ability to obtain illegal entry into susceptible hosts within a system. control plane: the act of executing a flooding attack by using fake sources has the potential to induce congestion inside the channel links. consequently, the disruption of communication between the sdn controller and the data plane components could isolate the sdn controller from the remaining network elements. in addition, the attacker can manipulate the trust that is formed heba dhirar al-khwarizmi engineering journal, vol. 21, no.3, pp. 3547 (2025) 38 between openflow switches with the controller to execute a man-in-the-middle attack, intercept valuable data or obtain complete control over the controller level [18]. application layer: the potential adversary can execute a harmful software programme to breach the established security protocols or bypass the firewall and ids applications. attacks on the control plane are reportedly exclusive to sdns, arising from the separation of the data and the control plane, although attacks on data and application planes are prevalent across sdn and traditional networks. 3.2. iot attack vectors the open web application security project [19] released an extensive preliminary document outlining the attack surfaces of iot devices. these attack surfaces refer to the specific places within iot systems and applications that are susceptible to vulnerabilities and potential security risks and can be categorised into three distinct types (fig. 1.b). devices: these tools serve as the principal means by which attacks can be established. the primary components of the device, including firmware, memory, a web interface, network surfaces and a physical interface, exhibit vulnerabilities. the attackers can exploit the default configuration, vulnerable update mechanisms and outdated components. the attackers can exploit the default configuration, vulnerable update mechanisms and outdated components. communication: the security of communication channels is a subject of concern. the channel serves as a means of connecting iot devices with the external environment. the communication protocol utilised in iot networks has security vulnerabilities that have the potential to impact the overall system. application software: this poses a significant threat to the security of online software and apps utilised on iot devices. these vulnerabilities can lead to system compromise. the online application can illegally acquire user data and introduce harmful upgrades into the system. fig. 1. a) sdn attack vectors, b) iot network attack vectors. 3.3. background attackers can use numerous methods to breach it systems, and the majority of cyber-attacks employ similar strategies. the most common attack types are as follows: scanning: the initial phase of an attack involves the process of scanning, which entails the collection of information about a target system. this feature includes identifying accessible ports and accessible services on the target device or sensor. dos attack: the attacker also has the potential to rapidly deplete the resources of the sdn controller by overwhelming the targeted system with a substantial volume of fake packets that lack corresponding rules inside the flow tables of switches. notably, the sdn controller serves as the central decision-making entity within the sdn; hence, the entire system becomes inaccessible to authorised users. this phenomenon results in the transformation of the network as a whole into an entity lacking cognitive capabilities. heba dhirar al-khwarizmi engineering journal, vol. 21, no.3, pp. 3547 (2025) 39 ddos attack: the dataset comprises many ddos attack scenarios, including udp flooding, icmp flooding and tcp-syn flooding attacks. the hping3 programme is well recognised as one of the tools most often used for conducting ddos attacks. brute force attacks: gaining unauthorised access to a victim’s workstation by attempting to crack the login credential information by creating a comprehensive dictionary of all conceivable combinations of usernames and passwords. the attacker machine utilised in this scenario is kali linux, whereas the target is the server. web-based attack: according to the 2018 research by symantec [20], approximately 10% of the urls tested were susceptible to web application attacks, indicating a significant 56% increase compared with the previous year. probe attack: this preliminary stage is crucial for an attacker to gather important information before commencing their attack. the attacker conducts a systematic examination of the target system to obtain pertinent information that can facilitate the exploitation of the remote system, including details regarding the operating system’s versions and open ports, amongst other factors. the use of the metasploit platform is employed to identify the accessible ports and vulnerabilities inside the web applications present. botnet attack: the unauthorised individual can manipulate several compromised devices, known as a botnet, to execute various harmful actions, such as data theft, fraudulent attacks and distributed ddos attacks against targeted servers or compromising web application servers. the botnet attack is executed by utilising the metasploit platform; in addition, a further instance of iot attacks is the mirai botnet. the botnet executed high-volume distributed ddos attacks [21]. therefore, an efficient and precises security mechanism is needed to safeguard iot applications. u2r attack: these malicious activities resemble regular network traffic and represent a significant risk to the network. therefore, attacks need to be identified and detected promptly [22]. the utilisation of the metasploit framework facilitates the acquisition of root privileges on the targeted machine. 4. experimental setup 4.1. proposed architecture the construction of a substantial dataset requires a range of application services to be implemented within an experiment-generated dataset. in this manner, contemporary attacks over the internet, which can be executed within today’s sdns, can be represented accurately. furthermore, the attack scenarios must include existing attack routes across various sdn components. moreover, a variety of attack scenarios are being investigated, originating from various sources intraand interdomain to the sdn. the topology is represented by constructing four subdomains by utilising mininet on the ubuntu 20.04 lts operating system. two ryu controllers are charged for managing the four openflow vswitch (ovs) switches that connect to these subdomains. the ryu controller is an opensource software that is based on the python language. this controller is widely recognised for its ability to manage demands efficiently and effectively in modern networking settings whilst also being scalable; it is also compatible with multiple sdn protocols and features, making it suitable for a range of networking scenarios and interactions with numerous technologies. the first two subdomains pertain to a conventional network that comprises various services, such as http and ftp servers. by contrast, the latter two subdomains correspond to an iot network specifically designed for conducting experiments indoors and outdoors. two base station nodes serve as the root of the tree, which have ids 1 and 11 (fig. 2). additionally, nine sensor nodes with ids are in the ranges of 2– 10 and 12–20. each subdomain comprises an access point that serves three mobile stations, resulting in a total of 12 stations and 20 sensing nodes in the entire network. each station and sensing node has been configured with a limited transmission range to facilitate indoor and outdoor traffic monitoring. fig. 2. root sensing node. data transmission must occur through an access point. a mobility feature has been activated to enable mobility-based data collection. in addition to the utilisation of attack machines, which are linuxbased metasploitable, this system is employed to offer vulnerable services that serve as a means to demonstrate prevalent vulnerabilities. the ovs heba dhirar al-khwarizmi engineering journal, vol. 21, no.3, pp. 3547 (2025) 40 switch is configured to operate as a layer-3 switch by integrating the ovs software with the routing capabilities of the linux kernel. in this scenario, the various virtual hosts can establish communication amongst themselves by utilising distinct subdomains. the subsequent procedure outlines the process of topology construction and execution: • a mininet topology consisting of eight virtual hosts (h1 to h8) is designed. • the virtual hosts within the mininet network are connected to distinct ovs switches, namely, sa1, sa1, sb1 and sb2. these switches are further linked to two additional ovs switches, sa and sb, to establish a tree topology. • the sensors are connected to the access point via tclink and are interconnected with each other via lowpan. • ryu controllers are initiated for the established network nodes, including switches and access points. successful network connectivity can then be established by sending icmp echo requests (pings) between hosts located in distinct subnetworks. fig. 3 illustrates the proposed architecture. fig. 3. proposed network architecture. 4.2. generation methods as an illustration, the attacker possesses the ability to produce harmful data flows to attack sdn controllers or potentially compromise communication channels connecting the sdn controller and openflow switches. once the flow of traffic is established, compromised individuals can be utilised to initiate subsequent attacks. notably, sdn applications may exhibit many vulnerabilities, including but not limited to command injection, buffer overflow and sql injection. these vulnerabilities have the potential to generate chances for attacks, enabling the attacker to circumvent the authentication process and gain unauthorised access to the controller by executing a malicious script. if the attacker can obtain unauthorised entry to the controller, then they can initiate additional offensive actions, including the modification of flow rules, the execution of a dos attack and the interception of data and control traffic for surveillance purposes. table 2 lists the attack categories employed within the virtual environment. heba dhirar al-khwarizmi engineering journal, vol. 21, no.3, pp. 3547 (2025) 41 table 2. dataset with attack classes produced within a virtual environment. attack description of activities dos tcp-syn, udp, icmp flooding ddos tcp-syn, udp, icmp flooding web attack xss, sql injection r2l imap, brute-force, mirai malware trojan, botnet probe probe scan, discover service, vulnerability scan, spoofing, packet sniffing, ping sweep u2r vsftpd, samba, passive exploitation the entirety of the generated network traffic is gathered and examined via wireshark. the data are subsequently labelled according to their profile and attack type, and its key features are extracted via cicflowmeter, which was created by the canadian institute of cyber security and uses java for network traffic flow generation from pcap files. fig. 4 illustrates the key stages involved in the traffic generation process. fig. 4. dataset generation process. 5. results and analysis the dataset was partitioned into three distinct groups according to the traffic type and target machine. the first category comprises exclusively regular traffic; the second category comprises attack traffic specifically directed from the metasploit server; and the third category comprises the attack on the iot device. the overall number of 39,608,114 occurrences for regular and attack traffic. the regular traffic yields a cumulative count of 11,638,252, whereas the attack traffic has 27,969,892 occurrences. table 3 shows the data records and their respective sizes. wireshark is utilised to gather traffic flows in each class on the victim computer and interface of the sdn controller. as mentioned, cicflowmeter is utilised to obtain the flow features of the dataset, and a separate dataset is deployed for each attack type and combined to produce the final dataset. the primary motivation for utilising the cicflowmeter is that none of the other tools specifically focus on timebased aspects [23]. nevertheless, various applications are subjected to distinct time limitations. consequently, the calculation of statistical time-related properties for flow traffic becomes incredibly important. the generated flows are computed bidirectionally, with the flow path (forward or backward) determined by the first packet in the flow. cicflowmeter generates over 80 metrics within a csv file, including protocol, byte number, duration, packet number and others. in the process of labelling, various aspects are utilised, including information about the source and destination ip addresses. table 4 shows some of the extracted features and corresponding details. table 3. total number of data records with their respective sises. group description instance number .pcap size normal group https, http, ftp, dns, mail, browsing, youtube,.etc. 11,638,252 485 mb heba dhirar al-khwarizmi engineering journal, vol. 21, no.3, pp. 3547 (2025) 42 attack group dos 26,678,409 4.58 gb ddos r2l (imap, brute-force attack) 765,522 97.82 mb web-based attack botnet probe (scan, discover service, vulnerability scan, spoofing iot group mirai 525,961 286 mb table 4. some of the extracted features and corresponding details. feature description attack description attack description flow id flow unique identifier fwd iat mean the average duration between two consecutive packets in the forward direction. down/up ratio upload and download ratio source ip ip address of the source host fwd iat std duration elapsed between the transmission of two packets in the forward direction. average packet size the average size of packet destination ip ip address of the destination host fwd iat total total time between two packets sent in the forward direction fwd segment size avg average size observed in the forward direction flow, iat max, the maximum duration between the transmission of two packets within a given flow. psh flag count amount of packets containing the push flag. idle max the maximum duration of inactivity observed before the resumption of activity in a flow. flow, iat min, minimum interval duration between the transmission of two packets inside a given flow. ack flag count amount of packets containing the ack flag. idle std the standard deviation of time duration of that flow remains idle before becoming active. fwd iat min minimum time between two packets sent in the forward direction urg flag count amount of packets containing the urg flag. attack type specify the attack type flow id flow unique identifier fwd iat mean average duration between two consecutive packets in the forward direction. down/up ratio upload and download ratio source ip ip address of the source host fwd iat std duration elapsed between the transmission of two packets in the forward direction. average packet size the average size of packet heba dhirar al-khwarizmi engineering journal, vol. 21, no.3, pp. 3547 (2025) 43 1.1.evaluation widely recognised ml and dl techniques have been used to evaluate dataset quality. the first step is the preprocessing phase, which involves removing duplicated and nonvaluable values, encoding and scaling the dataset to mitigate significant variations in values and then utilising several algorithms, such as the following: the logistic regression (lgr) model calculates the probability of an event on a dataset of independent variables, such as voting or not voting. the dependent variable is confined between 0 and 1 because the outcome is probabilistic. these formulas represent this logistic function, often known as log odds or the natural logarithm of odds: ℎ𝛩(𝑥) = 𝑔(𝛩𝑇𝑥) = 1 1 + 𝑒−𝜃𝑇𝑥′ …(1) 𝑤ℎ𝑒𝑟𝑒 𝑔(𝑧) = 1 1 + 𝑒−𝑧 k-nearest neighbours (knns) are nonparametric, supervised learning classifiers that classify or predict data point groupings on the basis of nearness. knns can be used for regression or classification. however, knns are usually used for classification, assuming that similar points are nearby. 𝑑(𝑥, 𝑦) = ∑ |𝑥𝑖 − 𝑦𝑖|𝑛 𝑖=1 …(2) naive bayes classifiers use bayes’ theorem for classification. the algorithms in this family have a similar premise. each pair of classed features is independent. 𝑃(𝐴|𝐵) = 𝑃(𝐵|𝐴) ∗ 𝑃(𝐴) 𝑃(𝐵) …(3) the most powerful and popular categorisation and prediction technique is decision tree classifiers (dtcs). a decision tree (dt) is a flowchart-like tree structure with internal nodes representing attribute tests, branches representing test outcomes and leaf nodes (terminal nodes) representing class labels. 𝐺𝑖𝑛𝑖(𝑃) = ∑ 𝑝𝑖(1 − 𝑝𝑖)𝑛 𝑖=1 …(4) 1 − ∑ (𝑝𝑖)2𝑛 𝑖=1 𝑤ℎ𝑒𝑟𝑒 𝑃 = (𝑝1, . . . , 𝑝𝑛 ) in supervised learning algorithm rfs, its ‘forest’ is a dt ensemble trained with a ‘bagging’ method. the bagging method combines learning models to improve the results. rfs are useful for classification and regression, which are common in ml systems; it can also resist dt overfitting. 𝐺𝑖𝑛𝑖(𝑃) = 1 − ∑ (𝑃𝑖)2𝑛 𝑖=1 …(5) the deep neural network (dnn) model utilised in this work is shown in table 5. table 5. neural network training model. algorithm family layers neuron dnn 5 dense 250,150,6 4,32,16 activation function relu, sigmoid loss function categorical cross-entropy optimizer adam batch-size 64 epochs 10 the studies were conducted via the python programming language, utilising a range of packages, including sklearn, keras and tensorflow, and the dataset was evaluated on the basis of the following metrics: accuracy, f1 score, precision and recall, which are described via the following equations: 𝐴𝑐𝑐𝑢𝑟𝑎𝑐𝑦 = 𝑇𝑟𝑢𝑒 𝑃𝑜𝑠𝑖𝑡𝑖𝑣𝑒𝑠 +𝑇𝑟𝑢𝑒 𝑁𝑒𝑔𝑎𝑡𝑖𝑣𝑒𝑠 𝑇𝑜𝑡𝑎𝑙 𝐼𝑛𝑠𝑡𝑎𝑛𝑐𝑒 … (6) 𝑃𝑟𝑒𝑐𝑖𝑠𝑖𝑜𝑛 = 𝑇𝑟𝑢𝑒 𝑃𝑜𝑠𝑖𝑡𝑖𝑣𝑒𝑠 𝑇𝑟𝑢𝑒 𝑃𝑜𝑠𝑖𝑡𝑖𝑣𝑒𝑠 + 𝐹𝑎𝑙𝑠𝑒 𝑃𝑜𝑠𝑖𝑡𝑖𝑣𝑒𝑠 …(7) 𝑅𝑒𝑐𝑎𝑙𝑙 = 𝑇𝑟𝑢𝑒 𝑃𝑜𝑠𝑖𝑡𝑖𝑣𝑒𝑠 𝑇𝑟𝑢𝑒 𝑃𝑜𝑠𝑖𝑡𝑖𝑣𝑒𝑠 + 𝐹𝑎𝑙𝑠𝑒 𝑁𝑒𝑔𝑎𝑡𝑖𝑣𝑒𝑠 …(8) 𝐹1 = 2 ∗ 𝑃𝑟𝑒𝑐𝑖𝑠𝑖𝑜𝑛 ∗ 𝑅𝑒𝑐𝑎𝑙𝑙 𝑃𝑟𝑒𝑐𝑖𝑠𝑖𝑜𝑛 + 𝑅𝑒𝑐𝑎𝑙𝑙 …(9) the metrics of the dtc and rf classifier (rfc) algorithms yield satisfactory results across all the other models. in general, the aforementioned algorithms achieved a high level of success in identifying the majority of attacks. figs. 5 and 6 show the results related to the diverse attack classes and model performance. fig. 5. performance metrics correspond to the model. heba dhirar al-khwarizmi engineering journal, vol. 21, no.3, pp. 3547 (2025) 44 the combined metrics exhibit a high level of performance across all classes, with a notable exception being the u2r category, which demonstrates subpar performance metrics. this phenomenon can be attributed to other categories often exhibiting greater dissimilarity than typical traffic patterns do. however, the u2r attack class significantly resembles regular data traffic. furthermore, the u2r flow records are smaller than the regular flow records within the same dataset. the system had a high degree of success in identifying the majority of attacks, but it exhibited relatively low performance in detecting u2r attacks. another noteworthy observation pertains to the potential masking of subpar performance on less common attack classes by the favourable outcomes achieved on the combined dataset. this phenomenon arises from the predominance of samples associated with dos/ddos and probing attacks. moreover, the duration of training is directly proportional to the number of data records. in other words, as the size of the records increases, the training time also increases. fig. 6. performance metrics correspond to the attack class. 1.2. limitations the historical record of sdn attacks remains undisclosed. hence, in this work, possible weaknesses were identified that may be exploited by taking the attacker’s viewpoint. • the testbed was constructed utilising a pair of sdn controllers that functioned equally with equal roles. the categories of security analysis functionalities for other controllers are disregarded. however, controllers may exhibit varying security modelling [24,25], which would require the implementation of different countermeasures. • the network topology may be constructed via physical devices to increase the availability of intrinsic information in sdns. a series of experiments were conducted to evaluate different attack scenarios and analyse their effects on the layers of an sdn architecture. • one of the primary constraints of the dataset under consideration is a significant imbalance in class distribution. this issue has the potential to introduce bias in the ids against the majority class, resulting in elevated false alarm rates and reduced evaluation accuracy. nevertheless, several methodologies exist for addressing the issue of imbalanced samples, as shown in prior research [25]–[29]. two distinct approaches can be employed: (a) the higher classes can be subdivided to generate a greater number of classes, and (b) the merging of multiple minority classes that exhibit similar traits can result in the creation of a singular new class. consequently, the problem of imbalance can be mitigated, leading to a notable increase in the prevalence ratio. 2. conclusion this work examined the lack of an openly accessible dataset obtained from sdn-based iot networks and produced an extensive dataset consisting of 86 features extracted from approximately 40 million records obtained from simulated sdn-based iot networks captured within two flow profiles, representing normal behaviour and 15 different attack types in two scenarios, interdomain and intradomain. in addition, the dataset was evaluated via several ml and dl methodologies, such as dtc, rfc, dnn, knn, bernoulli naive bayes and lgr. the outcome reveals high accuracy in successfully recognising the majority of attacks when the dtc and rfc models are employed and a low accuracy level in detecting the u2r attack category. nevertheless, an sdn is more vulnerable to malicious network traffic than traditional networking configurations are. within the traditional network architecture, an attack can affect only a specific segment of the network, which is 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( 2025) 35-47، صفحة 3، العدد21مجلة الخوارزمي الهندسية المجلد هبة ضرار 47 وداخلمجموعة بيانات اكتشاف التطفل في شبكة إنترنت األشياء الُمعّرفة بالبرمجيات: بين النطاقات 2حسين حمد علي، *1هبه ضرار بغداد، العراق بغداد، جامعة ، كلية الهندسة الخوارزمي، قسم هندسة المعلومات واالتصاالت 1،2 heba.d@kecbu.uobaghdad.edu.iq*البريد االلكتروني: المستخلص على نطاق واسع في العديد من تكوينات الشبكة. ومع ذلك، فإن تطوير التكنولوجيا الجديدة (sdn) يتم نشر الشبكات المعرفة بالبرمجيات ة التي ي يمثل العديد من نقاط الضعف والمخاطر التي ال تزال تشكل تحديات أمام الشركات المصنعة في معالجتها. تتمثل إحدى العوائق الرئيس في عدم وجود مجموعة بيانات يمكن الوصول إليها بشكل مفتوح، خاصة التي يتم الحصول (ids) تمت مواجهتها في نشر نظام كشف التسلل القائمة على ids ينتج هذا العمل مجموعة بيانات شاملة لتقييم فعالية .sdn وشبكات إنترنت األشياء المستندة إلى ،sdnشبكات عليها من على ست وثمانين ميزة مستخرجة ما يقرب من أربعين مليون سجل تم تشتمل مجموعة البيانات المجال.الشذوذ في اكتشاف الهجمات داخل والتي تم التقاطها ضمن ملفي تعريف تدفق يمثالن أنواًعا عادية وخمسة ،sdn الحصول عليها من محاكاة شبكات إنترنت األشياء المستندة إلى مستخدمة على نطاق الالعميق اآللي، والتعلملتعلم لعشر نوًعا مختلفًا من الهجمات. باإلضافة إلى ذلك، نعرض التقييم الذي يستخدم ستة أساليب . .dtc ،rfc ،dnn ،knn ،bnb ،lgr :واسع لمعرفات كشف المعلومات mailto:heba.d@kecbu.uobaghdad.edu.iq this is an open access article under the cc by license. al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 19, no. 3, september, (2023) p. p. 122 removal of ciprofloxacin antibiotic from synthesized aqueous solution using three different metals nanoparticles synthesized through the green method abdelmalik milad shakorfow* najah al mhanna** mohammed a. atiya*** ahmed k. hassan**** fatimah q. kadhim***** zainab a. mahmoud ****** azza hashim abbas ******* *elmergib university / libya ** german university of technology in oman/ oman ** *,** ** *,** ** **department of biochemical engineering/ al-khwarizmi college of engineering/ university of baghdad/ baghdad/ iraq ****environment and water directorate/ ministry of science and technology/ baghdad/ iraq ******* school of mining and geosciences/ nazarbayev university/ kazakhstan *email: dr_eng.malik@yahoo.co.uk **email: najah.almhanna@gutech.edu.om ***email: atiya@kecbu.uobaghdad.edu.iq ahmedkhh71@gmail.com: email**** qaf2622@gmail.com: email***** zainab.amahmoud@gmail.com: email****** :corresponding author *******email: azza.hashim@nu.edu.kz (3202 february 6 accepted; 2022 october 30 received) 2https://doi.org/10.22153/kej.2023.02.00 abstract this study investigates the possibility of removing ciprofloxacin (cip) using three types of adsorbent based on greenprepared iron nanoparticles (fe.nps), copper nanoparticles (cu. nps), and silver nanoparticles (ag. nps) from synthesized aqueous solution. they were characterized using different analysis methods. according to the characterization findings, each prepared nps has the shape of a sphere and with ranges in sizes from of 85, 47, and 32 nanometers and a surface area of 2.1913, 1.6562, and 1.2387 m2/g for fe.nps, cu.nps and ag.nps, respectively. the effects of various parameters such as ph, initial cip concentration, temperature, nps dosage, and time on cip removal were investigated through batch experiments. the results showed that 10 mg/l cip was removed by 100%, 92% and 79% within 180 min using fe.nps, cu.nps, and ag.nps respectively. in addition to this, kinetic models of the adsorption and mechanism of cip removal were studied. the cinematic analysis demonstrated that adsorption is a physics adsorption mechanism with an energy of 0.846 kj.mol-1, 1.720 kj.mol-1, and 3.872 kj.mol-1, while the low activation energies of 17.660 kj.mol-1, 13.221 kj.mol-1, and 14.060 kj.mol-1 for fe.nps, cu.nps, and ag.nps respectively. the kinetic removal process follows a pseudo-first-order model following a physical diffusion-controlled reaction. the data on adsorption was analyzed using the langmuir, freundlich, temkin, and dubinin models, as well as thermodynamic factors, indicating that the process is appropriate and endothermic sorption. the most practical adsorbent was fe.nps keywords: removal ciprofloxacin, green synthesis, iron, copper, silver, nanoparticles, adsorption, thermodynamics, and kinetics. mailto:dr_eng.malik@yahoo.co.uk mailto:najah.almhanna@gutech.edu.om mailto:atiya@kecbu.uobaghdad.edu.iq mailto:ahmedkhh71@gmail.com mailto:zainab.amahmoud@gmail.com mailto:azza.hashim@nu.edu.kz https://doi.org/10.22153/kej.2023.02.00 abdelmalik milad al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 1-22 (2023) 2 1. introduction antibiotic waste in water supplies is one of the most significant challenges facing communities today, especially when it is discovered in drinking water sources [1][2]. the presence of these medicines in large quantities has a negative impact on the ecology [3][4]. in the present time, the world emits harmful substances into the environment either directly or after chemical changes [5]. antibiotics are widely used because they treat a wide range of bacterial infections in humans, animals, birds, and fish [6]. ciprofloxacin is a type of antibiotic that is commonly used as a treatment for a variety of bacterial infections around the world [7]. fluoroquinolones have been found in aquatic environments in concentrations ranging from "1100 mg/l" [8]. the broad-spectrum fluoroquinolone pharmaceutical medication that is frequently utilized is "ciprofloxacin ((1cyclopropyl-6-fluoro-4-oxo-7-(piperazine-1-yl)1,4-dihydroquinoline-3-carboxylic acid hydrochloride hydrate)" [8]. drug contamination is also caused by trash from hospitals, housekeepers, and human excretion [9]. non-target persons and biota are at risk from improper disposal of antibiotic-loaded pharmaceutical wastewater [10][11]. many approaches, such as advanced oxidation processes (aops) bioremediation, ozonation, chlorination, and others, have been proposed to treat cip-contaminated wastewater. however, these methods have a number of drawbacks, including poor removal, difficult procedures, and significant energy needs [1]. furthermore, multiple studies have suggested that chlorinating antibioticcontaminated wastewater could form a carcinogenic byproduct. as a result, it is crucial to convert antibiotic compounds to safe compounds before discharging them into water systems [12]. traditional treatment approaches do not completely eradicate antibiotics because of their environmental stability and extended breakdown durations [13] [14]. antibiotic wastewater treatment necessitates substantial technological resources, with the adsorption process being seen as the most promising method because it is effective, simple to implement, and technically advanced. to remove pollutant molecules (adsorbates) from contaminated solutions, the procedure employs natural and synthetic materials (sorbents, adsorbents, and biosorbents) [15]. in the adsorption process, the adsorbent material chosen is a critical aspect in obtaining the required efficiency in terms of pollutant removal and cost [16][17]. before being used, the sorbents must have been tested in this environment to ensure that they can perform adsorption for a variety of pollutants. these tests must also consider the accessibility and costeffectiveness of the tested adsorbents [18][10]. several materials are available to use as adsorbents, like activated carbon, natural clay (modified bentonite), and polymer-based materials [2]. researchers have recently proposed using generated trash as an adsorbent in a creative or improved form [20][21]. metal nanoparticles (nps) prepared by the green synthesis method using plant extracts have become widely used as adsorbents in the removal of medicine from wastewater [22]. in addition. the green synthesis method is eco-friendly, cost-effective, and easy to develop on a large scale. green synthesis usually consists of three steps: (1) solvent media selection; (2) environmentally friendly reduction agents’ selection; and (3) stable, non-toxic compound nanoparticle selection [19] moreover, iron (fe.nps) and copper (cu.nps) nanoparticles are lower cost, have wide viability [25], simple to produce [26], are environmentally friendly, and have extensive dispersion of reactive surface sites [27] [28], while silver nanoparticles (ag.nps) are widely used as antibacterials, sensors, catalysts, and adsorbents [29] [30]. in this study, the adsorption of ciprofloxacin from synthesis wastewater has been successfully employed using iron nanoparticles (fe.nps), copper nanoparticles (cu.nps), and silver nanoparticles (ag.nps) nanoparticles have been successfully studied. in addition, "pseudo-first order, pseudo-second order, elovichs, and behnajadymodirshahlaghanbary (bmg)" models were used to evaluate the adsorption kinetics. the ciprofloxacin analysis was investigated using the langmuir, freundlich, temkin, and dubininmodels as well as the thermodynamic parameters [31]. 2. materials and methods 2.1 reagents and chemicals the ministry of industry (ibn sina centre) provided the ciprofloxacin used in this study with the characteristics of the drug as (molecular wight = 385.8 g/gmol, color: whit, purity: 99.9% and λmax = 276 nm), while green tea leaves purchased from the local market in iraq. a spectrophotometer (uv/vis 1800 shimadzu, japan) was used to abdelmalik milad al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 1-22 (2023) 3 measure the maximum wavelength α (nm). figure 1 illustrates the chemical structure of the drug. fig. 1. the cip structure. 2.2 preparation of the adsorbent the " fe.nps, cu.nps, and ag.nps" nanoparticles were made using the same processes as those used in earlier investigations [34][35], with the following modifications: "green tea" leaf extract was made with "20.0 g of green tea and 300 ml of distilled water (dw). the mixture was preheated on a magnetic stove at 85°c for half an hour. after that the suspended green tea impurities were filtered with" 0.45 μm filter paper and stored at 4°c for further use. by adding 3.25 g of fecl3, 4.996g of cuso4.5h2o, and 3.4g of agno3 salt to 200 ml of dw, a solution of 0.10 m fecl3, 0.1 m cuso4.5h2o, and 0.1 m agno3 was prepared. after slowly adding the prepared tea extract to each salt solution, the color of each solution changed from light yellow to black for iron, from white to green light for silver, and finally to a dark brown, and from colorless to brownish yellow, and finally to black for copper, the reduction of metal ions to zero valent for example fe (+3) to fe (0) when we added the plant extract {this extract is very rich in polyphenols compounds which are played as reducing agents for metal ions}, and from colorless to brownish yellow after that the ph was adjusted to 6 iron [36], 9 for copper and silver [37] [38], and the mixture was continually stirred for 15 minute. the nps precipitate was collected using vacuum filtration and immediately washed with water and ethanol. green fe.nps, cu.nps, and ag.nps were dried at room temperature overnight before being ground into fine powders. 2.2 characterization of nps the prepared nps were characterized using sem images were taken with a" tescan-vega3 model" to detect morphology and particles size of prepared nps. the functional groups of cu, ag and fe.nps were identified by ftir (iraffinity, shimadzu, japan). a" brunauer–emmett–teller (bet)" application was used to compute the specific surface area, pore size, and pore volume of nps. nanoparticle stability was determined using a "zeta potential analysis", and the size and "surface morphology" of the nps determined by atomic force microscopy (afm). 2.3 experiments of adsorption before adding nanoparticles, a stock solution of 10 mg/l of ciprofloxacin solution was prepared, and the ph. a batch of experiments was carried out to examine the adsorption process of ciprofloxacin on prepared nps. several operating parameters were met in the studies, including a ph ( 2–10), a dosage range of 0.1–1 g/l for fe.nps, cu.nps, and ag.nps, a contact time range of up to 180 minutes, contaminant concentrations of (2–15 mg/l), and temperatures of (20–50 °c). the ciprofloxacin solution was supplemented with a particular amount of targeted nps, and then agitated at 300 rpm in a closed system. 0.1 m h2so4 and 0.1 m naoh were used to bring the ph of the cip solution up to the desired level. the temperature was kept constant, and each parameter's optimal value was recorded. samples )10 ml( were obtained at various times throughout the experiments, and the change in cip concentration was determined through a uv/vis spectrophotometer. the ability of fe.nps, cu.nps, and ag.nps to extract antibiotic pollutants from aqueous solutions was assessed using r% removal efficiency and qe mg/g adsorbent capacity values using the following two formulas [34] [33]. % 𝑅𝑒𝑚𝑜𝑣𝑎𝑙 = 𝐶ₒ − 𝐶𝑡 𝐶ₒ × 100 … (1) 𝑄𝑒 = (𝐶ₒ − 𝐶𝑒 ) × ( 𝑉 𝑊 ) … (2) where cₒ is initial cip concentration (mg/l), ct is the concentration after adsorption being start (mg/l) and ce is equilibrium concentration (mg/l). v is the volume of cip solution (l) and w is the wight of cip (g). 3. results and discussions 3.1 characterization of nps a scanning electron microscope (sem) was used to illustrate the shape and distribution of the abdelmalik milad al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 1-22 (2023) 4 nanoparticles. according to the sem of fe.nps that is presented in figure (2a), the adsorbent surface is rough and contains many different disorganized aggregates. on the surface of the fe.nps wall, there were a number of grooves and deep ravines. the morphologic characteristics of the surface of the fe.nps are generally favorable because they offer active sites and a large surface area for the molecules that are adsorbed. figures (2b-c) show sem images of the generated cu.np and silver nanoparticles (ag-np). sem pictures revealed the shape and distribution of these components. because polyphenols are present on the surface of nanoparticles, irrelevant spherical nanoparticles were discovered that were compatible with copperand silver-based preparations employing extracts of green tea leaves fig. 2. scanning electron microscope (sem) micrograph of (a) fe.nps, (b) cu.nps, and (c) ag.nps the fe.nps ftir spectrum is shown in figure 3a. the " ftir analysis of fe.nps reveals a functional group of o – h at 3364 cm-1, indicating the existence of polyphenols [25] and the c=o appeared at 1635 cm-1 also referring to the presence of polyphenols. the functional groups of c-h, c-o-c and c=c appeared at 2924 cm-1, 1035 cm-1, and 1367 cm-1 belong to the oxidized polyphenols on the produced fe.nps. polyphenols are thought to behave as antioxidants in green tea extract as well. in the ftir analysis of cu.nps figure (3b), the presence of polyphenols is indicated by this the peak at 3411 cm-1 that belong to o-h stretching, along with the association between c-h asymmetrical stretching and certain signals in 2948, 1782, 1615, and 1029 cm-1, c=o of aromatic rings, c=c stretch, and c-oh bending respectively. based on ftir measurements, ag.nps with a wave range of 3371cm-1 to 1021cm-1 show characteristic peaks. wide and strong absorption peaks were identified between 3371 and 3259 cm-1, indicating the presence of polyphenols and extended hydroxyl vibrations (oh). carbonyl c=o was detected by a significant absorption, with c=c stretching frequencies peaking between 1639 and 1634 cm-1. figure 3c shows the vibration of the o-h delay, which could be caused by the other pits between 1160cm-1. fig. 3. ftir spectrum of (a) fe.nps, (b) cu.nps, and (c) ag.nps nanoparticles. the size and surface morphology of fe.nps, cu.nps, and ag.nps nanoparticles were investigated with the help of a atomic force microscopy (afm). the average nanoparticle size a b b c a abdelmalik milad al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 1-22 (2023) 5 for according to the afm for iron, copper, and silver nanoparticles were (85, 47, and 32 nm), respectively, as shown in figures (4a-c). figures (5a-c) illustrates the afm results of fe.nps, cu.nps, and ag.nps nanoparticles. fig. 4. afm images of nanoparticles composed of (a) fe.nps, (b) cu.nps, and (c) ag.nps. fig. 5. nanoparticles of (a) fe.nps, (b) cu.nps, and (c) ag.nps examined by atomic force microscopy. nanofluid stability was determined using a zeta potential analysis technique, as shown in figure 6ac, the zeta potential values were -19.34 mv for fe.nps, -17.5 mv for cu.nps, and -29.1 mv for ag.nps, it was proven that the nanoparticles were more agglomerative. fig. 6. zeta potential of (a) fe.nps, (b) cu.nps, and (c) ag.nps nanoparticles. blumenauer-emmer-teller (bet) data are shown in table 1, which explain and clarify the surface area. pore sizes for iron, copper, and silver nanoparticles were 34.8651 nm, 8.2568 nm, and 5.1843 nm, respectively. according to the iupac, pore sizes between 20 and 50 nm are considered mesoporous. a b c c a b c a b abdelmalik milad al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 1-22 (2023) 6 table 1, the bet parameters for fe.nps, cu.nps, and ag.nps nanoparticles. 3.2 cip removal under various conditions in a closed system, the removal of ciprofloxacin by fe.nps, cu.nps, and ag.nps" was studied, and the removal percentage was determined under various experimental conditions. uv-vis at a wavelength of 276 nm was used to take samples and analyze them at various time intervals. "initial ph was set to 2.5, 3, 4, 5, 7, 8, 9, and 10, initial ciprofloxacin concentrations were set to 2, 5, 10, and 15 mg/l, fe.nps, cu.nps, and ag.nps doses were set to 0.1, 0.25, 0.5, 0.75, and 1 g/l, and the solution temperatures were set to 20, 30, 40, and 50 °c. eq. 1 was used to determine the ciprofloxacin removal performance. 3.2.1 effect of adsorbent the adsorbent dosage is an important factor to consider due to its role in demonstrating the catalyst's capacity to deal with a particular initial contaminant concentration. the effect of fe.nps, cu.nps, and ag.nps dosages on ciprofloxacin elimination is shown in figures 7a-c, respectively. the ciprofloxacin removal was raised from 18% to 70% when fe.nps were used, and the adsorption dosage was increased from 0.1 to 1.0 g/l, while it improved from 20% to 54% when cu.nps were used, and from 18% to 45% when ag.nps were used. higher fe.nps, cu.nps, and ag.nps for ciprofloxacin adsorption improved the removal rate and effectiveness while maintaining the other parameters (drug concentration, ph, temperature, and contact time). this is because the total area and active site have both increased. [41]. for iron, copper, and silver nanoparticles, doses of 0.5g/l, 0.75g/l, and 1 g/l were chosen as the optimal values. a similar result was indicated by [3], [4]. fig. 7. effect of "(a) fe.nps , (b) cu -nps, and (c) ag.nps doses at ph =3, 10 mg / l ciprofloxacin, 40°c, 300 rpm and contact time of 60 min". nanoparticle bet parameters bet(m2/gm) volume of pores(cm3/gm) size of pores (nm) fe.nps 2.1913 0.0191 34.8651 cu.nps 1.6562 0.00839 8.2568 ag.nps 1.2387 0.000618 5.1843 abdelmalik milad al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 1-22 (2023) 7 3.2.2 effect of temperature at temperatures ranging from 20 to 50 °c, the influences on ciprofloxacin removal efficiency were investigated. the efficiency of ciprofloxacin at various temperatures is shown in figures 8 a-c. since fe.nps removed 36 percent, 40 percent, 54 percent, and 53 percent of ciprofloxacin at 20, 30, 40, and 50°c, respectively, 43 percent, 44 percent, 78 percent, and 49 percent with cu.nps, and ag.nps removed 31 percent, 40 percent, 52 percent, and 45 percent with ag.nps, it is possible to conclude that the removal rate of ciprofloxacin is influenced by temperature and increased with increase in temperature. this could be due to an increase in the number of sorption sites generated because of the breaking of some internal bonds near the active surface sites of the adsorbent. furthermore, the increasing temperature may increase the mobility of the cip, enabling it to penetrate further. as a result, there are more medicines interacting with adsorbent active surfaces." for fe.nps, cu.nps, and ag.nps", the optimal temperature was 40°c. similar observations were noted by [5]. fig. 8. the temperature effect on ciprofloxacin removal onto various adsorbents at (10 mg/l of cip), 300 rpm, one hours (a) 0.5 g/l and ph=10 of fe.nps, (b) 0.75 g/l and ph=4 of cu.nps, and (c) 1 g/l, and ph=4 of ag.nps. 3.2.3 effect of ph as shown in figures (9 a-c) , the influence of ph is compared to ciprofloxacin adsorption by nps. two reasons were identified in the studies as possibly accounting for the increased ciprofloxacin adsorption: (1) at low ph, the concentrations of h+ in the solution were very high, enhancing the electrostatic pull between h+ in the solution and the adsorbent surface, resulting in competition for adsorption sites between h+ and cip+; (2) at higher (ph10), h+ of active groups can be easily dissociated and provide more adsorption sites [44]. in acidic environments, antibiotic molecules are positive, with 99% of ciprofloxacin molecules being (cationic), 10% being ciprofloxacin +, and 95% being anionic. when the ph is 7, ciprofloxacin 0" predominates (zwitterion). a physi-sorption reaction between ciprofloxacin molecules and the active sites of" fe.nps, cu.nps, and ag.nps "may occur at ph = 10, 4, and 4, respectively. figure (9 a) demonstrates that fe.nps improved the efficacy of removal at a range of ph values (2.5, 3, 4, 5, 7, 8, 9, and 10) for 60 min, with increases of 21%, 54%, 69%, 72%, 70%, 68%, 81%, and 92%, respectively. while figure (9 b) abdelmalik milad al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 1-22 (2023) 8 showed that the percentage removal of ciprofloxacin by cu.nps increased at acidic ph and then decreased at basic ph as 36 percent, 51 percent, 78 percent, 50 percent, 43 percent, and 32 percent, a similar result was indicated by [6], [7], [8]. figure (9 c) explains the removal of ciprofloxacin by ag.nps and the same observation was made at 37%, 45%, 52%, 48%, 43%, 30%, 23%, and 21%. the optimum values of ph for the removal" ciprofloxacin by fe.nps, cu.nps, and ag.nps are 10, 4, and 4" respectively. fig. 9. the effect of ph on the removal of " ciprofloxacin at 10 mg/l of concentration", one hours, and 300 rpm onto (a) 0.5 g/l, ph10 and 40℃ of fe.nps, (b) 0.75 g/l, ph 4, and 40℃ of cu.nps, (c) 1 g/l, ph4, and 40℃. 3.2.4 effect of initial concentration figures (10 a-c) represent the effect of drug concentration on removal efficiency for ciprofloxacin adsorption in the range of 2, 5, 10, and 15 mg/l. by employing "fe.nps, cu.nps, and ag.nps", the removal percentage decreased from 100% to 81% ,81% to 39 % for fe.nps, while cu.nps showed 99 % to 83 %, 78 % to 42 %, and ag.nps removal efficiency decreased from 57 % to 54 %, 52 %, to 48 % as the concentration of ciprofloxacin increased. other researchers' observations [34] have similar results to this study. the initial ciprofloxacin concentration for more active sites of fe.nps, cu.nps, and ag.nps because they are likely to rise, resulting in ciprofloxacin molecule adsorption competition [42]. the driving force is accelerated, and the resistance to mass transfer is reduced, when the first concentration is high. within one hour of the process, the optimal value for the initial cip concentration with all adsorbents was "10mg/l", and the removal of ciprofloxacin was 81 %, 78 %, and 54 %. abdelmalik milad al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 1-22 (2023) 9 fig. 10. the effect of the ciprofloxacin concentration at 300 rpm, one hour, and t = 40°c (a) fenps of 0.5g/l, ph10, (b) cu.nps of 0.75g/l, ph4, and (c) ag.nps of 1g/l, ph4. 3.2.5 effect of contact time to indicate the equilibrium point, a time effect is an important parameter of the sorption process. at ph 4, 7, and 10, the effect of increased contact time is seen in figure 11. with more time, the batch system's ciprofloxacin removal efficiency improves. the process was initially fast because of the high driving force at high ciprofloxacin level, but when the amount of non-adsorbed " ciprofloxacin "molecules in the adsorbent active site decreased, the removal rate declined for all ph levels [49]. the " ciprofloxacin removal" at ph 4, 7, and 10 for one hour was "59%, 72%, and 81% by using fe.nps, and 80%, 43%, and 27% for cu.nps", while the removal of ciprofloxacin was 53%, 43%, and 22% for ag.nps. the " ciprofloxacin removal after 180 min. at 4, 7, and 10" were 92%, 93%, and 100% with fe.nps, and 92%, 70%, and 50% with cu.nps, while the removal efficiency was 79%, 67%, and 42% by using ag.nps. abdelmalik milad al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 1-22 (2023) 10 fig. 11. time effect at different ph (cip conc.10 mg/l, 0.5 g/l fe.nps, 0.75 g/l cu.nps, and1 g/l ag.nps, with constant temperature of 40 °c. 4. adsorption mechanism equations (3) and (4) were used to determine the mechanism of the sorption process. (3) and (4) [9][5] [10]. kinetics of intraparticle diffusion: 𝑞𝑡 = 𝐾𝑖𝑑 𝑡0.5+𝐶 …(3) kinetic model of liquid film diffusion: 𝐿𝑛 1 − 𝑞𝑡 𝑞𝑒 = −𝐾𝑓𝑑 × 𝑡 … (4) the intraparticle diffusion constants are kid (mg/g min0.5) and c (mg/g). the thickness of the boundary layer is indicated by the c parameter, while the liquid film diffusion constant is shown by kfd (m -1). when the linear trend fit from the qt vs t0.5 as presented in figures (12a-c) passes the point of origin of the parameter c = 0, that mean the intraparticle diffusion is the limiting rate. in figure (12a-c), the slop and intercept of the plot of ln (1qt/qe) versus t correspond to kfd and c. tables (2), (3), and (4) demonstrate the results of "intraparticle and film diffusion" experiments at different ciprofloxacin initial concentrations (4). the linear model in figures (12a-c) and (13a-c) did not pass through the origin, implying that the thickness of the boundary layer controls the adsorption process. the high values of the regression coefficients suggest that liquid film diffusion plays a more crucial role, and that a greater concentration gradient causes ciprofloxacin molecules to diffuse more quickly across the boundary layer surrounding the adsorbent. the c values strongly suggest that intr-aparticle diffusion was also utilized in the sorption process. in addition to diffusion, several adsorption mechanisms control the rate of intra-particle diffusion. such aberrations have been described in a number of scientific studies [51], [10]. abdelmalik milad al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 1-22 (2023) 11 table 2, model and liquid film diffusion on fe.nps at different cip conc. for the intra-particle adsorption mechanism. table 3, model and liquid film diffusion on cu.nps at different cip concentrations for the intra-particle adsorption mechanism. table 4, model and liquid film diffusion on ag.nps at different cip conc. for the intra-particle adsorption mechanism. liquid film diffusion intra-particle diffusion cip (mg l-1) r2 c(mg. g-1) kfd (min1) r2 c(mg/g) kid (mg g-1.min0.5) 0.9584 -0.1481 0.0318 0.9727 0.0498 0.7982 15 0.9834 -0.0212 0.0308 0.9963 0.3249 1.349 10 0.9926 -0.1047 0.0341 0.9931 0.1978 1.4592 5 0.9475 -0.0662 0.0398 0.9895 0.559 1.6584 2 0.9704 0.9879 average r2 abdelmalik milad al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 1-22 (2023) 12 fig. 12. the intraparticle diffusion at a different initial concentration of cip adsorption (temp 40c, 300 rpm, and 60 min) onto (a) fe.nps adsorbent dose of 0.5 g, ph10.(b) cu.nps sorbent dose of 0.75 g, ph4, and (c)ag.nps sorbent dose of 1 g, ph4. fig. 13. the liquid diffusion at a various concentration of cip adsorption (temp 40c, 300 rpm, and 60 min) onto (a) fe.nps adsorbent dose of 0.5 g, ph10.(b) cu.nps adsorbent dose of 0.75 g, ph4, and (c)ag.nps adsorbent dose of 1 g, ph4. abdelmalik milad al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 1-22 (2023) 13 5. adsorption isotherm langmuir, freundlich, temkin, [52][47] and dubinin isotherm [53] [22], have all modeled ciprofloxacin; the equations for these models are listed below. langmuir: 1 𝑞𝑒 = 1 𝑞𝑚𝑎𝑥 𝐾𝐿 ( 1 𝐶𝑒 ) + 1 𝑞𝑚𝑎𝑥 … (5) separation factor or dimensionless constant (rl) 𝑅𝐿 = 1 1 + 𝑏𝐶ₒ … (6) freundlich: 𝐿𝑜𝑔 𝑞𝑒 = 1 𝑛 log 𝐶𝑒 + log 𝐾𝐹 … (7) temkin: 𝑞𝑒 = 𝑅𝑇 𝐵𝑇 𝑙𝑛 𝐶𝑒 + 𝑅𝑇 𝐵𝑇 ln 𝐾𝐹 … (8) dubinin: ln 𝑞𝑒 = ln 𝑞𝑚 − 𝛽ƹ2 … (9) ƹ = ln 𝑅𝑇 (1+ 1 𝐶𝑒 ) …(10) 𝐸 + 1 √−2𝛽 … (11) 5.1 langmuir model figure (14a-c) shows the plots of various models, where qmax and kl are constants of langmuir model. these values were calculated using the slope and intercept of the presented graph, 1/qe vs 1/ce. as demonstrated in tables (5), (6), and (7), langmuir isotherms define the values where (r2) langmuir is greater than other models and homogenous adsorbent surfaces with the very same adsorbent surface are in langmuir (7). tables (5), (6), and (7) illustrate the constant b of langmuir, which was set at 25.125 for fe.nps, 22.0925 for cu.nps, and 0.3643 for ag.nps (7). when (rl > 1), linear (rl = 1), favorable (rl 1), or irreversible (rl = 0), rl is a dimensionless constant and is commonly used as a separating factor for the rl indicator values and unfavorable adsorption. the rl values for cip adsorption on "fe.nps, cu.nps, and ag.nps were (0.022170.0033), (0.00452-0.00451), and (0.2504-0.1793), respectively, and while these values indicated favorable cip adsorption on adsorbents, they also gave erroneous values between 0 and 1. the maximal absorption (qmax.) of cip per gram of fe.nps, cu.nps, and ag.nps was 9.95024, 8.3822, and 8.5034mg, respectively. for all adsorbents, the data fit well with the langmuir isotherm, indicating a homogeneous surface supply of active sites on the adsorbent. a similar observation was reported by [11] [3]. fig. 14. the plot showing the langmuir isotherm model at a different initial concentration of cip adsorption (temp 40c, 300 rpm, and 60 min) onto (a) fe.nps dose of 0.5 g, ph10.(b) cu.nps dose of 0.75 g, ph4, and (c)ag.nps dose of 1 g, ph4. abdelmalik milad al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 1-22 (2023) 14 5.2 freundlich isotherm model the freundlich isotherm is an experimental equation that considers a multi-layer sorption system on a heterogeneous surface, with the values )kf( and n confirming favorable sorption. from the plotted graph of log qe vs. log ce, the slope and intercept were estimated as shown in figure (15ac). the n constants affect adsorption favorability, and " values of n between 2 and 10 are generally satisfactory, while values between 1 and 2 are difficult, and adsorption characteristics less than 1 indicate poor adsorption" (n = 4.9417, 4.7236, 2.7078) as shown in tables (9), (10), (11) indicate acceptable adsorption [51]. fig. 15. the plot showing the freundlich isotherm model at a different initial concentration of cip adsorption (temp 40c, 300 rpm, and 60 min) onto (a) fe.nps dose of 0.5 g, ph10.(b) cu.nps dose of 0.75 g, ph4, and (c)ag.nps dose of 1 g, ph4. 5.3 temkin isotherm model the maximum binding energy and heat of sorption coefficients are "kt (l/g) and bt (kj/mol)". the slope and intercept of a plotted qe graph vs. ln ce were used to get the kt and bt values (16a-c). the kt and bt values represent minute changes in sorption heat and solid interactions between adsorbent and adsorbate, as seen in tables (8), (9), and (10).. tables (8), (9), and (10), together with the required coefficient of correlation, and the low correlation coefficient r2 indicates that the model has no applicability. abdelmalik milad al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 1-22 (2023) 15 fig. 16. the plot showing the temkin isotherm model at a different initial concentration of cip adsorption (temp 40c, 300 rpm, and 60 min) onto (a) fe.nps sorbent dose of 0.5 g, ph10.(b) cu.nps sorbent dose of 0.75 g, ph4, and (c)ag.nps adsorbent dose of 1 g, ph4. 5.4 dubinin isotherm model as demonstrated in tables (5), (6), and (7), the values qe and describe the degree and mean sorption energy per mole of adsorbate, which may be calculated from the slope and intercept of the graph plotted at ln qe versus ↋2 .figure (17a-c). for "fe.nps, cu.nps, and ag.nps", the e values were (0.8461, 1.7205, and 3.8727 kj/ mol, respectively, indicating physical adsorption e8 kj/ mol, while e lies between (8-16) denotes chemical adsorption [55][56]. because the r2 value is higher for all adsorbents, we can use this model. figures (15ac), (16a-c), (17a-c), and (18a-c) show the "adsorption isotherms" derived by four models, as well as "cip experimental" data, and it is obvious that the langmuir and dubinin techniques were closer fits in terms of r2. fig. 17. the plot showing the dubinin isotherm model at a different concentration of cip adsorption (temp 40c, 300 rpm, and 60 min) onto (a) fe.nps dose of 0.5 g, ph10.(b) cu.nps dose of 0.75 g, ph4, and (c)ag.nps dose of 1 g, ph4 abdelmalik milad al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 1-22 (2023) 16 table 5, isotherm parameters values of fe-nps. freundlich langmuir r2 n kf r2 b (l mg-1) qmax (mg g-1) 0.755 4.941 8.287 0.947 25.13 9.95 dubinin temkin r2 e (kj/mol) qm (µg/g) r2 bt (kj/mol) kt(l/g) 0.986 0.846 1.141 0.5837 0.258 7.029 table 6, isotherm parameters values of cu-nps. freundlich langmuir r2 n kf r2 b (l mg-1) qmax (mg g-1) 0.6602 4.7236 0.1512 0.9245 22.0925 8.3822 dubinin temkin r2 e (kj/mol) qm (µg/g) r2 bt (kj/mol) kt(l/g) 0.8955 1.7205 1.1009 0.8064 6.8995 40.4976 table 7, isotherm parameters values of ag-nps. freundlich langmuir r2 n kf r2 b (l mg-1) qmax (mg g-1) 0.907 2.708 3.013 0.903 0.363 8.503 dubinin temkin r2 e (kj/mol) qm (µg/g) r2 bt (kj/mol) kt(l/g) 0.991 3.873 1.033 0.908 3.155 0.167 6. adsorption thermodynamic at 298, 303, 313, and 323 k, the adsorption behaviors of various concentrations of" cip onto fe.nps, cu.nps, and ag.nps" were censoriously investigated, and the thermodynamic parameters of gibbs free energy ,entropy and enthalpy were obtained using equations 12 to 16. [56], [57]: ∆𝐺 ∘ = −𝑅𝑇 ln 𝐾𝑐 … (12) 𝐾𝑐 = 𝑞𝑒 𝐶𝑒 … (13) ∆𝐺 ∘ = ∆𝐻 − 𝑇. ∆𝑆 ∘ … (14) ln 𝐶𝑡 𝐶 ∘ = −𝑘𝑜𝑏𝑠𝑡 … (15) ln 𝐾𝑜𝑏𝑠 = ln 𝐴 − 𝐸𝑎 𝑅𝑇 … (16) using ln kc values for various temperatures, the gibbs free energy (∆g0) was calculated. according to eq.19, the slope and intercept at ∆h0 and ∆s0 of the graph of ∆g0 vs t. figure can be used to determine "enthalpy (∆h0 ) and entropy (∆s0)" (18a-c). tables (8), (9), and (10) show the free energy, enthalpy, and entropy values for iron, copper, and silver nanoparticles. the positive enthalpy (∆h0) value demonstrated endothermic sorption and favorable, indicating the spontaneous nature of cip adsorption onto fe.nps, cu.nps, and ag.nps [58], [56]. during the adsorption process, positive entropy change determines the increase in disruption at liquid / solid interfaces [58]. eq.16 was used to compute the activation energy, in which a represents the "arrhenius factor, r represents the gas constant (8.314 j / mol.k)", k represents the temperature in kelvin, ea represents the activation energy (kj/mol), and kobs (min-1) represents the rate constant eq.15 [59], [34]. the intercept and slope of ln (ct/c0) and the time t (min) were used to calculate these values. for "fe.nps, cu.nps, and ag.nps", the straight line of ln kobs versus 1 / t figure (19a-c) deviates by" 17.66 kj / mol, 13.22 kj / mol, and 14.06 kj / mol", respectively, diffusion-controlled processes are indicated by an activation energy (ea) value greater than 21 kj / mol, whereas chemically controlled processes are indicated by an ea value less than 21 kj / mol. [59]. abdelmalik milad al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 1-22 (2023) 17 y = -1590.3x + 0.7501 r² = 0.2176 -5 -4 -3 -2 -1 0 0.003 0.00315 0.0033 0.00345 ln k o b s 1/t b fig.18. relationship between ∆g0 and t of cip adsorption onto (a) "fe.nps at initial concentrations of 10 mg/l, ph=10, and 300 rpm for adsorption of cip with a dose of 0.5 g and 60 min, (b) cu.nps at initial concentrations of 10 mg / l, ph=4, and 300 rpm for adsorption of cip with a dose of 0.75 g" fig. 19. "relationship between ln kob against 1 / t to caculate ea at concentrations of 10 mg / l, and 300 rpm , 60 min for adsorption dose of cip on to (a) fe.nps with a dose of 0.5 g and ph10, (b) cu.nps with a dose of 0.75 g and ph4, and (c) ag.nps with a dose of 1 g and ph4" -3 -2.5 -2 -1.5 -1 -0.5 0 290 295 300 305 310 315 320 325 ∆ g t(k) a y = -0.0609x + 17.544 r² = 0.1631 -5 -4 -3 -2 -1 0 290 295 300 305 310 315 320 325 ∆ g t(k) b y = -1691.2x + 0.7828 r² = 0.6587 -5.2 -5.1 -5 -4.9 -4.8 -4.7 -4.6 -4.5 -4.4 -4.3 0.00304 0.00312 0.0032 0.00328 0.00336 0.00344 ln k o b s 1/t c abdelmalik milad al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 1-22 (2023) 18 table 8, thermodynamic study of cip adsorption onto fe.nps (cip conc.=10 mg/l, fe.nps dosage = 0.5 g, contact time= 60 min, and ph=10). ∆g0 (kj/mol) ∆h0 (kj/mol) ∆s0 (kj/mol.k) t=20°c t=30°c t=40°c t=50°c 21.067 0.073 -0.367 -0.749 -2.249 -2.301 table 9, thermodynamic study of cip adsorption onto cu.nps (cip conc.= 10 mg/l, cu.nps dosage= 0.75 g, contact time= 60 min, and ph=4). ∆g0 (kj/mol) ∆h0 (kj/mol) ∆s0 (kj/mol.k) t=20°c t=30°c t=40°c t=50°c 17.544 0.061 -0.017 -0.069 -4.108 -0.701 table 10, thermodynamic study of cip adsorption onto ag.nps (cip conc.=10 mg/l, ag.nps dosage= 1 g, contact time= 60 min, and ph=4). ∆g0 (kj/mol) ∆h0 (kj/mol) ∆s0 (kj/mol.k) t=20°c t=30°c t=40°c t=50°c 12.713 0.042 0.516 -0.069 -0.959 -0.593 5. conclusions three adsorbents fe.nps, cu.nps, and ag.nps were characterized using advanced techniques such as sem, afm, bet, zeta potentials, and ft-ir, with the results indicating that nanoparticles had favorable effects in the adsorption process. several parameters were studied to optimize the adsorption process, including, contact time, ph, temperature, and initial antibiotic concentration, and the best value of this parameter was ph10, 60 min, 10 mg/l, 40°c, and 0.5 g/l dosages for fe.nps, ph4, 60 min, 10 mg/l, 40°c, and 0.75 g/l for cu.nps, and finally ph4, 60 min, 10 mg/l, 40°c, and 0.75 g/l for ag.nps. the isothermal study showed the best-fitting models for the adsorbent fe.nps and cu.nps were the langmuir and dubinin models, respectively, whereas the best-fitting models for the adsorbent ag.nps were the dubinin and temkin models. both the endothermal nature and the spontaneous nature of the sorption process were mentioned by the thermodynamic element. when ∆g0 is negative, the nature of adsorption was spontaneous and feasible for all nanoparticles. finally, fe.nps was the most appropriate adsorbent compared with cu.nps and ag.nps in the order of "fe.nps > cu.nps > ag.nps". references [1] c. a. igwegbe, s. n. oba, c. o. aniagor, a. g. adeniyi, and j. o. ighalo, “adsorption of ciprofloxacin from water: a comprehensive review,” j. ind. eng. chem., vol. 93, pp. 57– 77, 2021, doi: 10.1016/j.jiec.2020.09.023. 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(2023) 1-22، صفحة 2، العدد19مجلة الخوارزمي الهندسية المجلد عبد الملك ميالد 22 **نجاح المحنة عبد المالك ميالد شاكر* ****كاظم* فاطمة قاسم **احمد خضير حسان** **محمد عبد عطية السراج* ******** عزة هاشم عباس****زينب عادل محمود* جامعة المرقيب / ليبيا * الجامعة األلمانية للتكنولوجيا في عمان / عمان** الهندسة الخوارزمي/ جامعة بغداد/ بغداد/ العراققسم الهندسة الكيميائية االحيائية/ كلية ********، ****، ** بغداد/ العراق /دائرة بحوث البيئة والمياه/ وزارة العلوم والتكنولوجية **** جامعة نزارباييف/ كازاخستان******* dr_eng.malik@yahoo.co.uk :البريد االلكتروني* najah.almhanna@gutech.edu.com:البريد االلكتروني** atiya@kecbu.uobaghdad.edu.iq البريد االلكتروني:*** ahmedkhh71@gmail.comالبريد االلكتروني:**** qaf2622@gmail.comالبريد االلكتروني:***** zainab.amahmoud@gmail.comااللكتروني:البريد ****** azza.hashim@nu.edu.kzالبريد االلكتروني:******* الخالصة الخضراءالجسيمات النانوية المحضرة بالطريقة ثالثة أنواع من من محلول مائي باستخدام (cipهذه الدراسة إمكانية إزالة السيبروفلوكساسين )تبحث النانوية توصيف الجسيمات (. تم ag. nps( وجسيمات الفضة النانوية )cu. nps( وجسيمات النحاس النانوية )fe. npsالحديد النانوية ) جسيمات مثل 32و 47و 85شكل كرة وبأحجام تتراوح من فأن الجسيمات النانوية التي تم تحضيرها تمتلكلنتائج التوصيف ووفقًا باستخدام طرق تحليل مختلفة المحضرة والي. تمت دراسة ، على الت ag. npsو fe. nps ،cu. nps كل منلـغرام متر مربع / 1.2387و 1.6562و 2.1913نانومتًرا ومساحة سطحها الجسيمات النانويةالحرارة وجرعة سيبروفلوكساسين ودرجةللمثل األس الهيدروجيني والتركيز األولي على إزالة السيبروفلوكساسين تأثيرات العوامل المختلفة cu. npsو fe. npsدقيقة باستخدام 180ل ٪ خال79و٪ 92و٪ 100 السيبروفلوكساسين بنسبةمن / لتر غراممل 10والوقت. أظهرت النتائج أنه تمت إزالة االمتزازالية أن الدراسات وأظهر إزالة السيبروفلوكساسينتمت دراسة النماذج الحركية لالمتصاص وآلية ذلك،على التوالي. باإلضافة إلى ag. npsو 13.221 وجول / مول كيلو 17.660بينما طاقات التنشيط مولجول / كيلو 3.872 و مولجول / كيلو 1.720و جول / مول كيلو 0.846فيزيائية بطاقة كانت تشير دراسة حركيات العملية الى ان عملية االمتزاز على التوالي. ag. npsو cu. npsو fe. nps كيلو جول/مول لكل من 14.060و كيلو جول/مول باإلضافة إلى .dubininو temkinو freundlichو langmuirز باستخدام نماذج من الدرجة األولى. تم تحليل البيانات الخاصة باالمتزا لنموذجا تخضع . أظهرت جسيمات الحديد النانوية كفاءه عالية مقارنة مع جسيمات النحاس للحرارة عملية االمتزاز كانت ماصهإلى أن التي اشارت الديناميكية الحرارية دراسة والفضة النانوية سيبروفلوكساسين من المحلول المائي باستخدام ثالثالإزالة المضاد الحيوي تم تصنيعها بالطريقة الخضراء معدنيةجسيمات نانوية mailto:dr_eng.malik@yahoo.co.uk*البريد mailto:dr_eng.malik@yahoo.co.uk*البريد mailto:najah.almhanna@gutech.edu.com**البريد mailto:najah.almhanna@gutech.edu.com**البريد mailto:atiya@kecbu.uobaghdad.edu.iq mailto:ahmedkhh71@gmail.com mailto:qaf2622@gmail.com mailto:zainab.amahmoud@gmail.com mailto:azza.hashim@nu.edu.kz this is an open access article under the cc by license : al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 21, no. 2, june, (2025), pp. 2341 removal of methylene blue from wastewater using al haji plant as a low-cost, eco-friendly adsorbent ruqaya k. adday1*, and hussein m. flayeh2 1,2department of environmental engineering. college of engineering, university of baghdad, baghdad, iraq corresponding author’s email: roqia.adday23111@coeng.uobaghdad.edu.iq (received 10 october 2024; revised 1 january 2025; accepted 9 february 2025; published 1 june 2025) https://doi.org/10.22153/kej.2025.02.002 abstract this study investigates the use of agricultural waste, specifically the al haji plant, for wastewater treatment. the term 'al haji plant' refers to species from the al haji genus, particularly "al haji maurorum " and "al haji canescens ", which are drought-resistant plants of the fabaceae family. traditionally, these plants are known for their medicinal and antimicrobial properties. in this research, waste from the al haji plant was converted into activated carbon (ac) as a lowcost and techno-economically viable biosorbent for the removal of methylene blue (mb) dye from wastewater. the production of ac involved two key steps: chemical activation using sodium hydroxide (naoh) and carbonisation at 300 °c. the properties and adsorption potential of the resulting ac were investigated. various parameters were studied, including ph, contact time, stirring rate, initial dye concentration, adsorbent dosage, and temperature. characterisation of the biosorbents was performed using scanning electron microscopy (sem) and brunauer–emmett–teller (bet) surface area analysis. the sem investigation showed notable pores in the al haji plant sample that could enhance the absorption of the mb dye. results indicated that the bet surface area for physical ac is 25.5796 m²/g. the surface area of chemical ac was reported as 16.2767 m²/g. the dye exhibited pseudofirst-order adsorption kinetics, with average rate constants of 0.020082 and 0.001589 for physical and chemical activation approaches, respectively. an adsorption isotherm study was performed using the langmuir model, which showed an r² value of 0.827 and a maximum adsorption capacity of 5.24 mg/g." the study of adsorption thermodynamics revealed that mb adsorption on al haji activated carbon is spontaneous and endothermic. keywords: al haji plant; batch sorption; kinetic models; methylene blue; thermodynamic parameter. 1. introduction recent years have witnessed a significant increase in freshwater use due to technological advancements and rapid population growth, leading to substantial quantities of wastewater that must be immediately discharged into the natural environment[1]. accelerated mechanical advancement has led to a significantly increased production capacity, an improved quality of life for humanity, and other repercussions, including the emergence of dangerous synthetic substances and dyes[2, 3]. dyes constitute a significant category of chemical industrial effluents in aquatic environments. they are among the numerous organic compounds that contaminate water systems, owing to their critical role and extensive application across various industrial sectors, including paper, textiles, leather, and food industries[4, 5]. methylene blue (mb) is among the most harmful metal contaminants released into water due to rapid industrialization and urbanization[6]. these contaminants are persistent, non-biodegradable, accumulate in essential organisms, and can cause significant health impacts in humans above specific concentrations[7, 8]. the ability to eliminate these colors from wastewater is essential for safeguarding human health and the environment[9]. to mitigate the escalating pollution from toxic metals, many physical and chemical remediation strategies, including photo degradation, have been developed[10, 11]. various methods such as mailto:roqia.adday23111@coeng.uobaghdad.edu.iq https://doi.org/10.22153/kej.2025.02.002 ruqaya k. adday al-khwarizmi engineering journal, vol. 21, no.2, pp. 23-41 (2025) 24 precipitation, membrane filtration, ion exchange, reverse osmosis, electro-coagulation and flocculation have been developed; nevertheless, they exhibit significant drawbacks, including high costs, hazardous sludge production, and selective contamination[12]. nonetheless, adsorption remains the preeminent approach due to its costeffectiveness, absence of toxic by-products, and ease of execution adsorption has emerged as the predominant method for wastewater treatment due to its simplicity, scalability, and efficacy in eliminating trace water pollutants[13, 14] .a range of materials has been examined as adsorbents for mb removal, including resin, silica, clay, and activated carbon. [15].activated carbon serves as a very efficient adsorbent owing to its plentiful useful groupings, permeability, substantial surface area, and a complex internal structure. it has been widely utilized to eradicate diverse organic and inorganic pollutants from biologically resistant contaminated waterways [16, 17]. commercial activated carbon is a commonly employed industrial adsorbent for processes of separation, purification, and recovery. however, it necessitates regeneration following each adsorption process and entails significant production costs. employing biomass waste, including peanuts husks, sugarcane bagasse, coconut shells, bamboo, rice husks, mango kernels, and teas residues, as a precursor for activated carbon is an effective method for decreasing the overall production costs associated with its creation [18], [19]. the two essential stages in the production of activated carbons are carbonation and reactivation. the aim of carbonizing is to reduce the amount of volatile compounds in the original material. the precursor undergoes pyrolysis at temperatures between 300 and 850 °c, leading to its degradation transforming into gases and tars primarily composed of hydrogen, oxygen, and nitrogen. the char generated by this process results in a high fixed carbon content but exhibits low surface area and porosity. thus, an activation phase is crucial for improving porosity and structural organization, leading to the formation of the highly porous solid referred to as ac. the two techniques for treating adsorbents are physical and chemical approaches. the physical approach for treating an adsorbent entails activation through heating in an oven. the chemical treatment of adsorbents entails activation through the addition of acids or alkalis, including h3po4, naoh, k2co3, and koh [20, 21]. the aim of the study is to employ the adsorption technique for effective removal of dyes (methylene blue) from industrial wastewater, with the goal of enhancing efficiency, reducing treatment duration from the aqueous solution. 2. materials and processes 2.1. materials the al haji residue was locally sourced from leftovers. the al haji plant used in this study was collected from its natural habitat in [al-ishaqi area in salah al-din governorate, iraq]. methylene blue (mb) was chosen as the target adsorbate . it was supplied from (merck, germany). methylene blue was directly used with distilled water. sodium hydroxide (naoh), employed as the activation agent with a minimum assays of 98% was purchased from england. the effect of each variable (e.g. ph, time, dosage) was studied individually using a single variable change approach with the other variables stabilising at their optimal values 2.2. preparation of activated carbon the al haji plant was used as a precursor for synthesizing activated carbon (ac). the sample was washed thoroughly with distilled water and dried at 105°c for 24 hours. it was then crushed into powder using a disk mill. the preparation of activated carbon was carried out by chemical activation. the material was first heated at 300°c for two hours while passing nitrogen gas over it at a rate of 500 cc/min. after that, it was activated with a 0.5 m naoh solution for 24 hours. following activation, the sample was thoroughly washed with distilled water multiple times to remove any remaining base, until a ph from 6 to7 was reached.", ensuring the removal of residual alkalinity. the material was then dried again at 105°c for 2 hours before storage in an airtight container to prevent moisture absorption. physical activation was conducted in a muffle furnace at 300°c for 2 hours under a controlled flow of co₂ gas at a rate of 500 cc/min for one hour. this step was followed by purging the system with n₂ gas at a flow rate of 500 cc/min for one hour, allowing the sample to cool to ambient temperature. these parameters were chosen to optimize pore structure and surface area based on previous studies[22, 23]. ruqaya k. adday al-khwarizmi engineering journal, vol. 21, no.2, pp. 23-41 (2025) 25 (a) (b) fig. 1. al haji plant (a) before burning (b) after burning 2.3. preparation of solutions methylene blue (mb) (c16h18n3scl.3h2o) (merck, germany), an analytical grade product, was utilized to prepare artificial wastewater. all of the materials were analytical quality. the stock mb (methylene blue) solution (0.5 g) was produced by using distilled. the stock solution later was diluted to the concentrations (25, 30, 40, 50, 70 ,100 mg/l) using distilled water. 2.4. batch adsorption experiments adsorption experiments in batch mode were conducted at room temperature utilizing 100 ml of methylene blue. the mixture was then vigorously shaken on a platform shaker until equilibrium was reached at different of the initial ph (2–10), adsorbent dosages (0.5–3 g/l), contact time (10– 90 min), initial mb concentration (25– 100 mg/l), stirring rate(200-1000 rpm),and temperatures (25, 30, 35, 40,45,and 50 ◦ c)the study also examined the adsorption of mb on al haji particles. following the adsorption trials, the solutions underwent filtration, and the concentrations of mb in the resulting liquid were analysed using a uv/vis-dr 3000. a wavelength of 668 nm was selected to obtain maximum absorption. [24] the removal percentage of methylene blue (mb), denoted as r%, was evaluated based on the initial and equilibrium concentrations as shown in eq. (1) r% = ((c₀ − cₑ) / c₀) × 100%, …(1) where, r denotes the removal percentage, while and represent the initial and equilibrium concentrations of mb (mg/l), respectively. the adsorption capacity of activated carbon at equilibrium is given by al haji the equilibrium adsorption capacity, (mg/g), was determined using the following equation. (2) [25, 26] 𝑞ₑ = (c₀ − cₑ )v m … (2) where qₑ represents the adsorbed amount of mb (mg/g), v denotes the sample volume (ml), and m refers to the mass of the added adsorbent (g) 3. results and discussion 3.1. effect of ph the ph level plays a crucial role in the adsorption of methylene blue dye onto adsorbents, particularly when physical or chemical activation methods are used because they affect the surface charge of the adsorbent material. for instance, in acidic media, adsorbents may have a positive surface charge, repelling positively charged dye molecules, while in alkaline media, the adsorbent surface may become negatively charged, attracting positively charged dye molecules. therefore, the optimization of ph is essential to maximize dye removal efficiency. the study found that physical activation led to better removal of methylene blue dye than chemical activation, particularly because physical activation improved the adsorbent's surface area, reactivity, and the interaction between the adsorbent and dye molecules. in contrast to physical activation, chemical activation is more sensitive to ph changes and may not achieve the same efficiency across a wide ph range. it shows 95.1704 % removal rate when ph is 4 for physical activated carbon where it has a lower dye removal rate of 84.072 % by chemical activation with ph of 4 [27]. ruqaya k. adday al-khwarizmi engineering journal, vol. 21, no.2, pp. 23-41 (2025) 26 fig. 2. effect of ph on the precent of dye removal on ac 3.2. effect of contact time through batch studies, the effect of contact duration on the ability of dyes to bind to activated carbon was investigated to reach the equilibrium depicted in figure 3. it depicts the movement of the dye molecule from the solvent to the adsorbent particle as it diffuses across the surface, which can be used to explain the mechanism of colour removal. according to the findings, activated carbon achieved equilibrium after operating for 90 minutes. the adsorption capacity remained unchanged after 90 min, the dye removal rate reached 96.484 % for physical activation and 87.52 % for chemical activation. the adsorption rate initially increased significantly before progressively decreasing as a result of saturation. the physical adsorption's passive uptake or the ion exchange of the adsorbent surface may be used to define the fastphase sorption. physical activation typically results in enhanced adsorption capacity and accelerated adsorption rates relative to chemical activation, particularly when accounting for the temporal aspect of the experiment. physical approaches enhance the accessibility and efficacy of adsorption sites, making them preferable for the rapid and efficient removal of pollutants such as methylene blue [28-30]. fig. 3. effect impact of contact time on ac's dye removal percentage 3.3. effect of stirring rate the thickness of the adsorbent film formed by the particles that revolve in the adsorption system of a liquid makes the difference. this is mainly due to the rate of solute diffusion to the particle surface, which plays a crucial role in the adsorption process, the accomplment resulted in showing that when the agitation speed raised from 200 rpm to 1000 rpm the augmentation of agitation strength showed an effect on the elimination rate. this might be seen in figure 4 at a speed of 400 rpm for the physically activated samples where dye removal rate reached 97. 862 %. however the increase in the removal efficiency is no significant. this proves the effectiveness of physical activation in eliminating mb due to its impact on surface properties and adsorption rate. while(mb) is found to have less virustatic than in the stirring case, indicating that the stirring speed has little impact. on the film thickness. 400 rpm was the stimulation rate used in each experiment the dye removal rate is reaching 90.275 % for chemical activationthe physical activation of haji plant demonstrated higher efficiency in eliminating mb. this can be attributed to physical treatments (such as uv irradiation or thermal treatment), which enhance the surface characteristics of the adsorbent, thereby improving both the adsorption rate and ruqaya k. adday al-khwarizmi engineering journal, vol. 21, no.2, pp. 23-41 (2025) 27 overall efficiency. these approaches enhance the contact between dye molecules and the plant surface without introducing substances that may disrupt the adsorption process. chemical activation may result in the generation of undesirable by-products or diminish the long-term efficacy of the adsorbent[31, 32]. fig. 4. effect of stirring rate on the precent of dye removal on ac 3.4. effect of adsorbent dose the effects of different ac concentrations (0.5.1, 1.5, 2,2.5, and 3g) on absorption was investigated at ph = 4 , dye concentration of 25 mg/l mb, and shaking duration (90 min) as shown in figure 5. the rate of adsorption was generally observed to increase with the amount of adsorbent used. when the adsorbent concentration was increased from 0.5 to 3 g, this increase became more apparent where most of the dye is eliminated in 90 minutes. beyond 3 g, the dye concentration was hardly varied. the dye removal rate for physical activation is 98.552% at a concentration of 3 g of activated carbon, while the dye removal rate for chemical activation is 90.968% at the same concentration. the increased surface area of the adsorbent and the growing number of adsorption sites are responsible for the increase in dye removal percentage as the adsorbent dose rises. the superior efficacy of physically activated carbon in eliminating methylene blue is due to its enhanced porous structure, increased surface area, improved adsorption kinetics, and advantageous surface chemistry. these features enable physical activation to produce an adsorbent that is more efficient in adsorbing big organic compounds, such as methylene blue, than chemically activated carbon[33, 34]. fig. 5. effect of adsorbent dose on the percent of dye removal on ac 3.5. effect of initial concentration figure 6 illustrates the impact of the initial methylene blue concentration (25–100 mg/l) on the effectiveness of methylene blue removal. the studies, which were carried out at room temperature (25 °c), ph 4.0, and a swirling speed of 400 rpm, used a fixed dose of adsorbent (3 g). the effect with respect to the initial dye concentration is determined by the direct relationship between the initial dye concentration and the available binding sites on the sorbent surface. figure 6 illustrates the effect of the initial dye concentration. the percentage of dye removal often decreased as the initial dye concentration increased, which may be explained by the saturation of adsorption sites on the adsorbent ruqaya k. adday al-khwarizmi engineering journal, vol. 21, no.2, pp. 23-41 (2025) 28 surface. at low concentrations, the adsorbent surface exhibited open active sites; however, when the initial dye concentration increased, the active sites required to adsorb dye molecules disappeared. perhaps because to the significant driving force on mass at a high starting dye concentration, increasing the initial dye concentration results in an increase in the adsorbent's loading capacity. stated otherwise, the residual concentration of dye molecules will be larger at higher initial dye concentrations. at low concentrations, the absorption rate becomes independent of the initial concentration, because the number of dye molecules is smaller than the number of available absorption sites. the removal rate reaches 97.176% for physical activation and 89.588% for chemical activation. physical activation is more efficient because it improves the surface characteristics of the plant material, hence augmenting its capacity to absorb mb. chemical activation, conversely, may not enhance adsorption to the same degree because it does not directly influence surface area or surface activity in a comparable manner [35, 36]. fig. 6. relation between initial dye concentration on precent removal for different dyes on ac 3.6. effect of temperature the effects of temperature on mb adsorption on al haji are shown in figure 7. it was observed from figure 7 that the amount of methylene blue removed by al haji increased as the temperature increased. similarly, the mb extraction efficiency of al haji increased from 86.828% to 98.552% when the temperature was raised from 25 °c to 50 °c. for both physical and chemical activation, the mb removal performance of al haji improved from 66.828% to 86.836% over the same temperature range. the study showed that when the temperature increases, the effectiveness of removing mb also improves. this indicates that the process of removing mb is endothermic[37]. when there is a sufficient amount of energy, such as high temperature, the quantity of molecules that interact with the active site on the surface will increase according to[38]. the adsorption effectiveness increased at high temperatures because of the internal diffusion that controlled the adsorption process. this is because increase in temperature increases the movement of the solute physical activation is more efficacious at elevated temperatures as it augments membrane permeability and accelerates cellular processes without the hazards of chemical breakdown or toxicity. chemical activation, conversely, is more susceptible to temperature-induced breakdown, diminishing its total efficacy[39, 40]. fig. 7. effect of temperature on the precent of dye removal on aac ruqaya k. adday al-khwarizmi engineering journal, vol. 21, no.2, pp. 23-41 (2025) 29 3.7. ftir analysis of al haji powder and aac untreated sample (before activation) 3400.50 cm⁻¹: this peak represents the o-h stretching vibration, characteristic of hydroxyl groups (alcohols, phenols, or water). the broadness of the peak suggests hydrogen bonding, which is typical in plant cell wall components like cellulose, lignin, and other phenolic compounds. these hydroxyl groups play a key role in adsorption by forming hydrogen bonds with other molecules or metal ions during the adsorption process. 3232.70 cm⁻¹:o-h stretching vibrhydrogen bonding environments in the, 2916.37 and 2848.86 cm⁻¹: these-h stretching vibration methyl (–ch₃) and *methylene (–ch₂) groadsorption because, 1730.15 cm⁻¹: tc=o stretching vibration, carbonyl groups (found adsorption processes, 1637.56 and 1616.35 cm⁻¹: these=c stretching in aromatic rings (such as those in lπ-π interactions , 1537.27 cm⁻¹: this peak is associated with n-h bending vibrations, which are typical of amine groups. amine groups, found in alkaloids, proteins, or amino acids, can interact with metals or other species via electrostatic interactions or complexion, 623.01 and 472.56 cm⁻¹: these lowfrequency peaks are typically associated with metaloxygen bonds, suggesting that mineral or inorganic components in the plant material may interact with metals or ions during adsorption. these peaks may reflect the presence of minerals in the plant structure. physically activated sample (e.g., heating or grinding) in this case, the physical activation process alters the sample structure, which influences the ftir spectrum. physical activation typically enhances the surface area and modifies the hydrogen bonding, which can facilitate adsorption. 233.70 cm⁻¹: similar to the untreated sample, this peak corresponds to the o-h stretching vibration. a slight shift compared with the untreated sample could indicate changes in the hydrogen bonding network of hydroxyl groups, possibly due to physical treatment that alters the molecular interactions in the sample.2918.30 cm⁻¹this is again the c-h stretching vibration from methylene and methyl groups, indicating that the aliphatic components remain unchanged by physical activation. the presence of these groups facilitates hydrophobic interactions in the adsorption of organic contaminants or ions. 1710.80 cm⁻¹: this shift in the c=o stretching vibration suggests some reorganization or change in the carbonyl environment, possibly due to the alteration of ester or acid groups during physical activation. this change could enhance the ability of the material to interact with adsorbents, such as metal ions or organic molecules. 1612.49 and 1508.41 cm⁻¹: these peaks, linked to c=c stretching vibrations in aromatic rings, indicate that the aromatic components of the plant material are still present, albeit slightly altered due to physical activation. these changes might enhance π-π interactions during the adsorption of organic molecules. 1111.00 cm⁻¹: this peak is likely due to c-o stretching (in alcohols, ethers, or esters) and indicates the presence of polar functional groups that can engage in hydrogen bonding or electrostatic interactions with metal ions or organic contaminants during adsorption. 781.17, 623.01, and 472.58 cm⁻¹: these peaks remain consistent with the untreated sample and suggest the continued presence of mineral or inorganic components, which could be responsible for metal ion adsorption or complexion at the surface of the plant material. chemical activation such as through acid–base treatments leads to the breaking of chemical bonds, modification of functional groups, and the formation of new reactive sites within the material. this process significantly alters the adsorption properties by increasing the number of functional groups that can interact with adsorbates. 3165.19 cm⁻¹: this peak is associated with o-h stretching, but the shift to a lower wavenumber indicates weaker hydrogen bonding or possible protonation of the hydroxyl groups after chemical treatment. this could make the material more hydrophilic and capable of forming stronger interactions with metal ions or polar molecules. 2926.01 cm⁻¹: this peak is from c-h stretching in methylene and methyl groups, indicating that aliphatic groups remain intact after chemical activation. these groups may still contribute to hydrophobic interactions during adsorption. 1570.06 and 1516.05 cm⁻¹. these peaks correspond to c=c stretching in aromatic rings. the shift in these peaks suggests that aromatic components might be altered by chemical activation, which could increase π-π interactions during adsorption of aromatic pollutants or metal ions. 1382.96 and 1153.43 cm⁻¹: these bands are associated with n-h bending and c-n stretching vibrations, suggesting that amine groups or amide functional groups were modified during chemical activation. these amine groups can form complexes with metal ions or interact with organic pollutants. 1029.29 cm⁻¹: this peak corresponds to c-o stretching, likely from alcohols or ethers. the presence of these groups after chemical treatment suggests an increased surface polarity, which may enhance the material's ability to adsorb polar contaminants. 887.26 cm⁻¹: this peak may be due to c-h bending vibrations in ruqaya k. adday al-khwarizmi engineering journal, vol. 21, no.2, pp. 23-41 (2025) 30 aliphatic or aromatic structures. the shift here could indicate some structural reorganization after chemical activation. 781.17, 626.87, and 474.49 cm⁻¹: these peaks are still associated with metaloxygen bonds, indicating that chemical activation did not alter the inorganic components of the plant. these may be key in adsorption of methylene blue [23, 41-44]. fig. 8. ftir (a) al haji powder (b) al haji physical activated carbon (c) al haji chemical activated carbon ruqaya k. adday al-khwarizmi engineering journal, vol. 21, no.2, pp. 23-41 (2025) 31 3.8. scanning electron microscopy (sem) a scanning electron microscopy technique was utilized to examine the surface morphology of both the al haji powder and the prepared al haji activated carbon (aac ( . unprocessed sample (500 nanometres): the particle size is extremely small (500 nanometres), which gives the material high structural stability. no cracking or defects are observed, as the material has not been subjected to any external forces, maintaining its original form. the pore distribution in this sample is relatively uniform, with smaller pores dominating the structure. physically activated sample (10 micrometres): this activation leads to greater cracking and an increase in brittleness due to the mechanical stress applied during processing, making the particles more susceptible to cracking and defects. the material exhibits a nonhomogeneous structure, with a broader distribution of pore sizes, including larger pores, which result from the physical activation process. the increased brittleness and cracking make the structure less stable and more prone to irregularities. chemically activated sample (10 micrometres): on the other hand, chemical activation enhances the structural integrity of the material by improving molecular bonding, making it more stable and resilient compared to physical activation. the chemical treatment leads to a more homogeneous pore structure with improved molecular bonding, which reduces brittleness. this treatment not only strengthens the material but also promotes the formation of more uniform pores, with a more controlled distribution of pore sizes compared to the physically activated sample"[45-47]. (a) (b) (c) fig. 9. sem images of (a) al haji powder (b) al haji physical activated carbon (c) al haji chemical activated carbon the elemental compositions of the raw material (al haji) and aac were examined using an energy dispersive spectroscope (edx). high carbon content (67.7%) the untreated sample figure (a) has a very high carbon content, indicating that it is primarily composed of organic materials such as carbon-rich compounds (e.g., hydrocarbons, polymers). this could be a natural or synthetic material, potentially a polymer or organic compound with little to no processing oxygen (32.1%)oxygen is present as part of oxygencontaining functional groups (e.g., hydroxyl, carbonyl, or ether groups), typical in organic materials or biological compounds low nitrogen and sodium (0.2% and 0.1%, respectively) the presence of nitrogen and sodium in trace amounts ruqaya k. adday al-khwarizmi engineering journal, vol. 21, no.2, pp. 23-41 (2025) 32 suggests minimal contamination or the presence of minor inorganic species. physically activated sample figure (b) reduced carbon content (49.5%) the significant reduction in carbon content (from 67.7% to 49.5%) after physical activation suggests that physical processes such as heating, compression, or grinding led to the breakdown or removal of some carbonaceous material. this could result in a material with a less carbon-rich structure, potentially altering its chemical composition or surface characteristics. increase in oxygen content (48.0%) the increased oxygen content could indicate oxidation during physical activation, or the introduction of more oxygenated functional groups to the material's surface, which can improve its reactivity or interaction with other chemicals nitrogen (1.4%) and sodium (1.1%) the increase in nitrogen and sodium suggests that the activation process could have introduced nitrogenous species (such as amines or nitrates) and sodium, possibly from atmospheric exposure, contaminants, or from additives used during activation. the nitrogen content is notably higher compared to the untreated sample, which might indicate that some nitrogenous compounds were introduced during the physical activation process. chemically activated sample figure (c) carbon content (61.3%)the carbon content in the chemically activated sample is somewhat higher than in the physically activated one but lower than the untreated sample, indicating that the chemical activation process altered the carbon structure. chemical activation often involves the use of reagents (such as acids, bases, or salts) that can introduce new surface chemistry or modify the material oxygen content (34.4%) the oxygen content is lower than in the physically activated sample, which suggests that the chemical activation process did not oxidize the material as much as physical activation did. chemical activation typically involves reactions with chemicals that can introduce specific functional groups without overly oxidizing the structure sodium (3.4%) the high sodium content in the chemically activated sample could be due to the use of sodium-based reagents or salts during activation, which are commonly used in chemical activation processes. this may indicate that sodium compounds are incorporated into the structure of the material, affecting its chemical reactivity and properties nitrogen (0.9%) the nitrogen content is slightly higher than in the untreated sample, suggesting that some nitrogenous species were introduced during chemical activation, possibly through the use of nitrogen-containing reagents [4851]. table 1, elemental composition of samples a: edx analysis of al haji powder b: edx analysis of physical activated carbon element raw sample (%) physically activated sample (%) chemically activated sample (%) carbon 67.7 49.5 61.3 oxygen 32.1 48.0 34.4 nitrogen 0.2 1.4 0.9 sodium 0.1 1.1 3.4 ruqaya k. adday al-khwarizmi engineering journal, vol. 21, no.2, pp. 23-41 (2025) 33 r: edx analysis of al haji chemical activated carbon fig. 10. edx(a) al haji powder (b) al haji physical activated carbon (r) al haji chemical activated carbon 4. adsorption isotherms the isotherms adsorption method is employed to evaluate experimental data to characterize the equilibrium correlation between the dose of the adsorbent and the adsorption of the adsorbate over a period of time. as shown in figures (11) (12) the experimental equilibrium data of (mb) adsorption on ac were analysed using two linearized isotherm models, namely langmuir and freundlich. the langmuir isotherm and freundlich isotherm calculations for (mb) onto ac were conducted based on eqs.3 and 4 respectively. the langmuir model, based on adsorption equilibrium assumptions, is given by equation (3). 𝑞𝑒= qmkac𝑒 1 + kace … (3) while the langmuir model's linearized form could be expressed using eq. (4): 1 𝑞𝑒 = 1 𝑞𝑚 + 1 qmk𝑎 1 𝑐𝑒 … (4) where: qe: is the amount of sorbate adsorbed per unit mass at equilibrium(mg/g). qm: is the maximum adsorption capacity(mg/g). ce: is the equilibrium adsorbate concentration (mg/l). ka: is the equilibrium constant of adsorption (l/mg). the langmuir constants, qm, and ka, are calculated from the slope and intercept of the 1/qe vs. 1/ce plot. the separation factor, denoted as 𝑅𝐿, is a dimensionless constant that represents the fundamental properties of the langmuir isotherm. it may be calculated using equation (5) as described by [52]. 𝑅𝐿 = 1 1 + kac𝑎 … (5) applying the freundlich model by the equation (6). 𝑞𝑒 = 𝐾𝐹ce 1⁄𝑛 … (6) a linearized version of the above equation is given in eq (7): ln 𝑞𝑒 = ln𝐾𝐹 + (1⁄𝑛) ln 𝐶𝑒 …(7) where: kf: freundlich adsorption constants showing adsorption capacity (mg/g) n: constants of freundlich adsorption(l/mg) ce: is the equilibrium concentration(mg/l) qe: is the amount of sorbent adsorbed per unit mass at equilibrium(mg/g). fig. 11. linear form of the isotherm models for sorption of (mb) onto ac (a) langmuir, (b) freundlich for cane physical ac. ruqaya k. adday al-khwarizmi engineering journal, vol. 21, no.2, pp. 23-41 (2025) 34 fig. 12. linear form of the isotherm models for sorption of (mb) onto ac (a) langmuir, (b) freundlich for cane chemical ac. table 2, parameters of langmuir and freundlich equations for sorption of (mb) on ac model parameters al haji physical activated carbon al haji chemical activated carbon langmuir qmax (mg/g) 5.238345 5.47046 ka (l/mg) 0.256759 0.096791 r 2 0.777 0.9686 freundlich kf (mg/g) 1.646645 1.291814 n 0.3384 3.1210 r 2 0.7271 0.9341 the analysis of the data presented in table 2 reveals that the r2 values linked to the langmuir model were superior than those of the freundlich model. these findings indicate that the adsorption of (mb) on activated carbon (ac) can be better described by the langmuir model rather than the freundlich model for aac. the present work provides evidence of a monolayer adsorption phenomena occurring within a system that is compatible and uniform, thereby correlating with the results previously documented by[53]. 5. sorption kinetic models the adsorption kinetics onto the al haji were determined using pseudo-first-order and pseudosecond-order models, as shown in figures 13,14 and table 3. indeed, both models effectively explain the correlations between the empirical and theoretical findings the first-order kinetic model is often used to describe adsorption processes where the rate of adsorption is proportional to the concentration of adsorbate (molecule or ion) remaining in the solution. this model assumes that adsorption occurs on a surface with a finite number of identical sites, and the adsorbate is assumed to form a monolayer on the surface without interaction between adsorbate molecule while the pseudo-second-order kinetic model is widely used to describe the adsorption of solutes (adsorbents) onto solid surfaces (adsorbents). this model is often more suitable for describing the adsorption process in many real-life applications compared to the firstorder model, especially when the adsorption is not simply proportional to the concentration of the adsorbate [54, 55] equivalent equations (8) and (9) denote the non-linear manifestations of pseudofirst-order and pseudo second-order kinetics, correspondingly [56]. dq𝑡 d𝑡 = 𝑘1 (𝑞𝑒 − 𝑞𝑡) … (8) dq𝑡 d𝑡 𝑑𝑡 = 𝑘2 (𝑞𝑒 − 𝑞𝑡) 2 … (9) the values of q𝑡 and q𝑒 (mg/g) indicate the quantities of ac that were adsorbed onto the mb at any given time (t) and at equilibrium, respectively. the rate constants of the pseudo-first-order and pseudo second-order kinetics are denoted by the values k1(min--1) and k2 (min--1) correspondingly. equations (10) and (11) provide the linearized definitions of the pseudo-first-order and pseudosecond-order, respectively[26, 57]. dq𝑡 d𝑡 𝑑𝑡 = 𝑘2 (𝑞𝑒 − 𝑞𝑡) 2 … (10) 𝑡 q𝑡 = 1 k2q𝑡 + 𝑡 q𝑡 … (11) ruqaya k. adday al-khwarizmi engineering journal, vol. 21, no.2, pp. 23-41 (2025) 35 fig. 13. kinetic model for sorption of mb on al haji (a)pseudofirst order kinetic for physical activated (b) pseudofirst order kinetic for chemical activated fig. 14. kinetic model for sorption of mb on al haji(a)pseudosecond order kinetic for physical activated (b) pseudosecond order kinetic for chemical activated table3, adsorption kinetics parameters of pseudo-first-order rate and pseudo-second-order rate equations for (al haji plant) model parameters al haji aac physical ac chemical ac pseudofirst order k1 (min-1 ) -0.00059 -0.00042 qe (mg/g) -18.8324 -26.2467 r 2 0.9456 0.9073 pseudosecond order k2 (mg/g min) 0.020082 0.001589 qe (mg/g) 2.471577 26.80965 r 2 0.986 0.9751 based on the previous analysis, the pseudosecond-order model demonstrates a higher capability to describe the adsorption process in the studied system. this is not only due to the high (r)2 values but also because of the positive and logical values of the adsorption capacity (qe) and the rate constant (k). these results reflect the multifaceted nature of the adsorption mechanism and highlight the importance of considering multiple factors when selecting the appropriate model. ruqaya k. adday al-khwarizmi engineering journal, vol. 21, no.2, pp. 23-41 (2025) 36 6. thermodynamic parameters three thermodynamic parameters, namely enthalpy change ∆𝐻o, gibbs free energy change ∆𝐺𝑜, and entropy change ∆𝑆o, were examined to analyse the thermodynamic behaviour of the relationship among the thermodynamic parameters enthalpy change ∆𝐻𝑜, entropy change ∆𝑆𝑜, and gibbs free energy change ∆𝐺o is defined by the equation(12) [58, 59] . ∆𝐺𝑜 = 𝑅𝑇𝑙(𝐾𝑐) … (12) where r is the universal gas constant (𝑅 =8.314 𝑘𝐽⁄𝑘𝑚𝑜𝑙. 𝐾), t is the absolute temperature of the solution (k), and 𝐾𝑐 is the distribution coefficient that can be calculated by eq. (13). 𝐾𝑐 = 𝑞𝑒 𝐶𝑒 … (13) where qe represents the quantity of adsorbed methylene blue per unit weight of activated carbon at equilibrium concentration (mg/g), and ce denotes the equilibrium concentration of methylene blue (mg/l). the relationship between the thermodynamic parameters, enthalpy change (δh°) and entropy change (δs°), determines the spontaneity of the adsorption process. consequently, the alteration in gibbs free energy, ∆g𝑜, is delineated by the equation (14) ∆𝐺𝑜 = ∆𝐻𝑜 − 𝑇∆𝑆𝑜 ...(14) substitution eq. (10) in eq. (8) gives lnkc= − δ𝑆o r δho rt ...(15) the values of ln(kc) were calculated by eq. (9) at different temperatures. plotting ln(𝐾𝑐) vs. 1\t gives a linear relation from which the values of ∆𝐻𝑜 and ∆𝑆𝑜 are calculable. fig 15 illustrates that the value of 𝐾𝑐 escalates with an increase in temperature parameters ∆g° , ∆h° , and ∆s° at various temperatures for the adsorption of methylene blue onto aac. fig. 15. thermodynamic model for sorption of mb on al haji (a)physical activated carbon (b) chemical activated carbon table 4, thermodynamic parameters for the adsorption of mb on ac (al haji) t( c) physical activated carbon chemical activated carbon ∆g◦ (kj /mol) ∆s◦ (j.mol-1 .k-1) ∆h◦ (kj /mol) ∆g◦ (kj /mol) ∆s◦ (j.mol-1 .k-1) ∆h◦ (kj /mol) 298 -5.02223 253.07816 70.85607 -2.73391 108.1153 29.384 303 -5.69883 -3.30176 308 -6.58155 -4.20247 313 -8.24698 -4.46239 ruqaya k. adday al-khwarizmi engineering journal, vol. 21, no.2, pp. 23-41 (2025) 37 the adsorption process for both physical and chemical activation is endothermic, as indicated by the positive δh values meaning it requires heat energy for the adsorption to occur. this explains why adsorption increases with higher temperatures, as heat energy supports the process. the negative values of δg indicate that the adsorption process is spontaneous at the studied temperatures. as the δg values become more negative with increasing temperature, this suggests that the process becomes more favourable and spontaneous at higher temperatures. the positive values of δs mean an increase in randomness or entropy when reacting. in the context of adsorption, this means that the particles of the adsorbent (solid surface) and the adsorbed (methylene blue) move to a more random state after absorption, such as the random distribution of particles on the surface [60, 61]. 7. conclusions in this study, the al haji plant was successfully used for the removal of methylene blue dye from aqueous solutions. the results indicate that the plant's physical and chemical properties played a significant role in the adsorption process. the plant demonstrated good potential as an eco-friendly and cost-effective adsorbent material for the removal of methylene blue, achieving notable decolourization and reduction of dye concentration. physicochemical characteristics the adsorption process was influenced by various factors such as the plant's surface area, functional groups, and particle size. the plant's cellulose and lignin content, along with its natural surface charge, may have contributed to the dye adsorption efficiency. this achieved a 98.552% removal of methylene blue with a mixing duration of 90 minutes, a ph of 4, a stirring rate of 400 rpm, a dosage of 3 g/100 ml of activated carbon, and an initial methylene blue concentration of 25 ppm. the results suggest that the adsorption process likely involves a combination of physical and chemical interactions between the dye molecules and the surface of the adsorbent. the study suggests that both van der waals forces and electrostatic interactions might be involved in the removal process. comparative effectiveness when compared to other traditional adsorbents, the al haji plant appears to be a competitive alternative, offering a more sustainable approach to treating wastewater contaminated with dyes like methylene blue. 8. limitations and challenges 1. necessity for additional inquiry into adsorption mechanism: although the study yielded encouraging outcomes, further comprehensive investigations are required to thoroughly clarify the adsorption mechanism. comprehending the specific nature of the interactions (e.g., ionexchange, hydrogen bonding, or surface complexation) is essential for enhancing the material's efficacy. 2. while a single variable change approach was used to study individual effects, the interactions between variables were not examined in this research. it is suggested that a more comprehensive experimental design (such as full factorial design) be used in the future to study the possible overlaps between different factors. 3. lack of comprehensive statistical analysis: the study did not include a thorough statistical analysis of the data collected during the experiments. statistical analysis is essential for determining the reliability of the results and assessing variability in performance across different samples. for instance, analysis of variance (anova) or t-tests could be used to test for significant differences between means and to ensure that the results are not due to chance. additionally, statistical analysis could help identify the most influential factors on the adsorption process and contribute to optimizing the experimental design. 4. the study did not include a control experiment using the raw, untreated material. this was a deliberate decision, as the primary focus was on evaluating the enhancements achieved through chemical and physical activation processes. however, including a control experiment could provide additional insights and may be considered in future research. 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( 2025) 23-41، صفحة 2، العدد21مجلة الخوارزمي الهندسية المجلد رقية كريم عداي 41 منخفضة مازة كمادة الحاجي نبات بواسطة الصحي الصرف مياه من االزرق الميثيلين إزالة للبيئة وصديقة التكلفة رقية كريم عداي1*، حسين مجيد فليح2 قسم الهندسة البيئية، كلية الهندسة، جامعة بغداد، بغداد، العراق 1،2 roqia.adday23111@coeng.uobaghdad.edu.iq :البريد االلكتروني * المستخلص وخاصة ، الحاج جنس من نباتات إلى غالبًا الحاج” “نبات مصطلح يشير الحاج، نبات ساق وتحديدا الزراعية النفايات استخدام في العمل هذا يبحث alhagi maurorum أو alhagi camelorum ، البيئات مع التكيف على بقدرتها النباتات هذه تُعرف البقوليات. عائلة إلى تنتمي صحراوية نباتات وهي يرتبط الثقافات، بعض وفي للميكروبات. والمضادة للبول والمدرة لاللتهابات المضادة لخصائصها الشعبي الطب في تقليديًا تُستخدم الشائكة. وفروعها الجافة المواد هذه تعتبر فعالة. بيولوجية ممتازة مواد إلى النفايات مواد تحويل طريق عن إنتاجه يتم الذي أغصانه. على يتشكل سكري إفراز وهو بـ”المّن”، النبات هذا تم الحاجي. نبات بقايا من المصنوع (ac) المنشط الكربون تحضير عملية وصف تم الصحي. الصرف مياه لمعالجة واقتصاديا تقنيا مجديا موردا الممتزة 300 عند والكربنة (naoh) الصوديوم هيدروكسيد باستخدام التنشيط المنتج. المنشط الكربون امتصاص وكفاءة والكيميائية الفيزيائية الخصائص في التحقيق مختلفة معلمات دراسة تمت (.mb) األزرق الميثيلين المتصاص المنشط الكربون استخدام تم المتردد. التيار تصنيع في الرئيسيتان الخطوتان هما مئوية درجة والوقت الهيدروجيني الرقم ذلك في بما الرئيسية، التشغيلية المعلمات تأثير فحص تم األزرق. الميثيلين امتزاز كفاءة على آثارها إلظهار الغرفة حرارة درجة في المجهر باستخدام الحيوية للممتازات فحص إجراء تم الصبغة. إزالة عملية على الحرارة ودرجة الممتزات وجرعة األولية الصبغة وتركيزات التحريك ومعدل المجهر تحقيق يظهر (.bet) وتيلر وإيميت بروناور سطح ومساحة (ftir) فورييه من المحولة الحمراء تحت واألشعة (sem) الضوئي المسح اإللكتروني أن إلى النتائج تشير (.mb) األزرق الميثيلين صبغة امتصاص تعزز أن يمكن التي الحاج نبات عينة في ملحوظة مساما (sem) الضوئي المسح اإللكتروني m²/g 16.2767 أنها على الكيميائي المنشط الكربون سطح مساحة عن اإلبالغ تم /جم.²م 25.5796 هي المادي المنشط للكربون bet سطح مساحة m2g−1 . والكيميائي، الفيزيائي التنشيط لنهج 0.001589و 0.020082 معدل ثوابت متوسط مع األولى، الدرجة من زائفة امتزاز حركية الصبغة أظهرت تبلغ قصوى امتزاز قدرة إلى أدى مما ، 0.827 من أكبر 2r بقيمة langmuir المتزاز الحرة متساوي باستخدام الحرة متساوي دراسة أجريت التوالي. على وعفوي. للحرارة ماص aac على mb امتزاز أن لالمتزاز الحرارية الديناميكا في التحقيق يوضح . g-1 ملغ 5.238345 mailto:roqia.adday23111@coeng.uobaghdad.edu.iq this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 20, no. 2, june, (2024), p p. 2638 performance analysis of different machine learning algorithms for predictive maintenance noor a. mohammed*, osamah f. abdulateef **, ali h. hamad*** and oday i. abdullah**** *,** department of automated manufacturing engineering , al-khwarizmi college of engineering, university of baghdad, baghdad, iraq *** department of information and communication engineering, al-khwarizmi college of engineering, university of baghdad, baghdad, iraq **** system technologies and engineering design methodology, hamburg university of technology, 21079 hamburg, germany corresponding author *email: noor.ali2204@kecbu.uobaghdad.edu.iq **email: drosamah@kecbu.uobaghdad.edu.iq ***email: ahamad@kecbu.uobaghdad.edu.iq ****email: oday.abdullah@tuhh.de (received 4 october 2023; accepted 27 november 2023; published 1 june 2024) https://doi.org/10.22153/kej.2024.11.003 abstract this research offers an extensive study of different machine learning issues for predictive maintenance applications for motor condition ranging from ac motors. the research establishes a scenario that represents the real world to identify which algorithms can be trusted to predict both the time of failure and the actual type of failure in the ac motors. the employed machine learning algorithms include the random forest (rfc), support vector classifier (svc), k-nearest neighbor (knn), logistic regression (lr), and xgboost (xgb) in our work. the assessment includes the comparison of algorithms in terms of the predictive accuracy educated with different size training data. before the model is developed, thorough data preprocessing methods will be applied that will allow the breaking down of the model assumptions and the optimization of the performance. for preprocessing step the following two steps are made including the removal of unclear samples, label encoding used for categorical columns, and column scaling. intriguingly, the identification of seemingly outlier data points is revisited, revealing their integral role in capturing the natural variance of the dataset and enhancing classification tasks. these identified features are observed to be pivotal contributors to predictive models. the study shows that in both algorithm failure cases and failure type identification, their performances are comparable. regarding training time, k-nearest neighbors (knn) algorithm yields the top-performing model for both datasets ( 4 sec and 3 sec) respectively, whereas random forest (rfc) performs the worst training time (151 sec) which belong to the binary failure prediction task and xgboost (xgb) in multi-class failure prediction task (276 sec), which is contributed. finally, this paper emphasizes that deciding on which machine learning model is appropriate for predictive maintenance can be quite a challenge due to the necessity to balance between accuracy and training time. the findings constitute important tipping point for those companies that aim to implement a solution for predictive maintenance with the knn model being faster and efficient at the same time. keywords: predictive maintenance; machine learning algorithm; random forest (rfc); support vector classifier (svc); k-nearest neighbors (knn); logistic regression (lr); xgboost (xgb) 1. introduction the digitization technology offers lots of perspectives, among which is predictive maintenance (pdm). by the means of sensors one could make a difference between the factors that need adjusting, the algorithm is able to translate such imperfections into preventative measures and mailto:drosamah@kecbu.uobaghdad.edu.iq mailto:ahamad@kecbu.uobaghdad.edu.iq https://doi.org/10.22153/kej.2024.11.003 noor a. mohammed al-khwarizmi engineering journal, vol. 20, no.2, p.p. 2638(2024) 27 the issue could be fixed either by machine or by a human. these elements undoubtedly exert profound influence in the mpm paradigm [1]. predictive maintenance will have future maintenance or a preventive which comprises monitoring of system/component condition based on experience, physical principles, or by machine learning techniques. the target is to acquire the locations of the bad components and deduct them before they are broken down which results into the system being offline for a shorter duration of time. smart, monitoring-based maintenance (in fact predictive maintenance) is seen as a sustainable and affordable solution to increase availability and the amount of time that equipment can perform in the different industry sectors. prognostics describe the process of determining the predictable functioning of the system or its components in the future, depending on their current state of health. during the predictive maintenance method development, this model will play a crucial role, being the cornerstone. the use of predictive maintenance and prognosistic models greatly extends and is seen in different kind of industry environments, for example electronics, aerospace, automotive and industrial machinery, with the number of applications growing rapidly [2]. there exist two primary classes of pdm solutions: aimed at fundamentally grounded physical concepts and learning (with machine-based comprehension methods). on one hand, solving problems by way of models requires an exclusive domain expertise, which is often not accessible. on the other hand, data based approaches are designed to learn predictive models from data that is available, which renders them applicable to wide range of problems in pdm. machine learning provides tools for algorithms that are able to independently handle data based on complex statistics for data analysis and forecasting. the algorithms in the neural networks should be designed to work without being programmed explicitly for a particular task; rather they should be self-learning and autonomous. these algorithms should be able to authentically acquire insights from the data provided and generate accurate predictions. by the same token, machine learning has suddenly become a practical tool not only in the computer science field, but also other professions (people begin to utilize these tools to achieve their own goals) [3]. from the maintenance perspectives, the predictive maintenance with the spotlight on machine learning that is an important driver in the industry for reaching performance and cutting the costs related to the downtime is the top tool for raising reliability of machines. predictive maintenance includes identification of equipment failures upfront and stopping unexplainable downtime using data analyze features from various sources such as sensors, historical maintenance records, and operation records. the machine learning application has a crucial role in the predictive maintenance and automatically reveals the mistakes in the data that is missing and defective thus making the identification of the possible problems before they can escalate much easier. the historical data can be used by machine learning models to detect some predictive behaviours in equipment like impending failure. similarly, these models can predict the length of time that machine will work and give the commuters heads-up when equipment is getting dangerously close to its failure threshold, allowing team to fix it before that happens. through predictive maintenance which is based on machine learning techniques, the giant saving is being achieved by way of decreasing the frequency and duration of equipment breakdowns, improving efficient performance and prolonging in-service life of equipment. in addition to this, it supports maintenance teams to choose the areas that require their attention instead of the ones that are routine like the routine maintenance tasks [4]. nowadays, predictive maintenance (pdm) obstacles were the focus of many studies that used machine learning techniques as a tool. an actual use case from the field of pdm that used two deep learning models was provided by silvestrin et al. [5] that compared with more classic machine learning models, which based on feature engineering. these results illustrated that even relatively simple algorithms can do learning using a small number of examples rather than deep ordering models as a result of their small number of parameters. this outcome is a clear testament for the applicability of a simple ml algorithm along with rudimentary feature engineering techniques when data availability turns out to be a hurdle in pd tasks. also, based on 6 study by ashok k pundir and others [6] researchers created an intelligent pdm framework for aerospace industry that can be used both by researchers and professionals.through their work, they accomplish both specific functions simultaneously. first, predictive maintenance will get more attention as an ml-based model will be developed. the data showed that the random forest model outperformed the others, the model could correctly predict ttf by ±28 cycles with a small difference of 28.7 cycles in particular. the authors of work by shing-jie pan et.al. [7] offered a technique of developing regression model for the noor a. mohammed al-khwarizmi engineering journal, vol. 20, no.2, p.p. 2638(2024) 28 super-critical ultra-pressure chemical reactor having a bearing with prediction on health. this mode is based on a criteria function referred to as piecewise linear remaining useful life (plrul), which is that estimates are made from machine learning regression techniques using data from acceleration and three-phased motor current (a/m) datasets.chaitali r. patil et. al [8] to start, information on machine health were used to present in a uniform output. such a method collected, stored and sent audio information to the edge devices and the cloud seamlessly and a highly efficient manner. through this tool, sensor data was experienced to visualize the machine's condition, frequently generating reports on the machine's health. to understand when the machines were failing they would use prediction tools that would ring and informthrough notificationskey players of the industry.the proposed approach aims to achieve real-time predictive maintenance for industrial machines, aligning with the goals of industry 4.0, which prioritize process optimization, cost reduction, and enhanced efficiency as primary drivers. mudita uppal et al. [9], introduced a cost-effective and user-friendly intelligent office system. their approach is suitable for practical implementation in real office environments, offering real-time monitoring of office conditions. they developed an interactive graphical user interface (gui)-based smartphone application for overseeing the various appliances and sensors integrated into the smart office. these appliances and sensors are interconnected with arduino, which transmits data to a cloud server. the collected data, originating from diverse devices (e.g., air conditioning, television, printer) and sensors (temperature, humidity, fire, motion, etc.), is continuously monitored through the smartphone application and server to predict potential faults using machine learning algorithms. two different techniques, namely “k-nearest neighbors (knn)” and “naive bayes (nb)”, were applied to the dataset. knn outperformed nb in terms of accuracy, recall, specificity, and f1-score, achieving an impressive accuracy rate of 99.63%, while nb achieved only 92.3% accuracy. additionally, knn exhibited a specificity of 0.99 compared to nb's 0.83. therefore, knn demonstrated superior performance over nb in this context. mounia achouch et. al [10] conducted a study where they utilized machine learning algorithms to predict failures and estimate the remaining useful life (rul) of a ta-48 multistage centrifugal compressor. their main goal was to reduce system downtime by applying a predictive maintenance strategy rooted in industry 4.0 principles. to accomplish this, they adhered to a predictive maintenance process, encompassing data exploration and preprocessing to prepare the data for model training. they performed a thorough comparison of different prediction algorithms to choose the most appropriate one, ultimately deciding on lstm neural networks. additionally, they improved the model's performance by regularly updating and expanding the dataset. as a result, the deployed model enabled operators to foresee compressor failures and make proactive decisions, guaranteeing minimal system downtime. salim qadir and mohammed hussein [11] applied binary classification methods for intrusion detection, employing multiple supervised machine learning algorithms as classifiers. they assessed the effectiveness of each model by measuring various metrics such as accuracy, precision, recall, f-score, error rate, true positive rate, false positive rate, and examining the confusion matrix. most of the current pdm studies use only one machine learning algorithm, which poses a challenge to extrapolating single-model approaches to real ac motor applications. therefore, this paper proposes a pdm method that uses five distinct machine learning algorithms, namely “random forest (rfc)”, “support vector classifier (svc)”, “knearest neighbors (knn)”, “logistic regression (lr)”, and “xgboost (xgb)”, for the purpose of predicting potential machine failures and conducting a comparative analysis of these algorithms. to assess the effectiveness of these machine learning techniques in a practical predictive maintenance (pdm) context, we employed the ac motor condition monitoring dataset. our approach involves training these algorithms with datasets of varying sizes, and subsequently examining how changes in the size of the training data impact their performance by comparing accuracy curves on the test data. the proposed pdm can not only monitor the state of the ac motor in real-time but also predict the fault of the motor in advance. 2. implementing a machine learning algorithms machine learning is a discipline focused on enabling computers to acquire knowledge without the need for explicit programming. arthur samuel gained renown for his checkers-playing program, a notable early example. machine learning (ml) serves the purpose of instructing machines on how noor a. mohammed al-khwarizmi engineering journal, vol. 20, no.2, p.p. 2638(2024) 29 to effectively process data, particularly when data interpretation is challenging. ml becomes necessary when we struggle to extract meaningful insights from information. given the wealth of available datasets, the demand for machine learning is steadily increasing, with numerous industries relying on it to derive valuable information. in essence, the primary objective of machine learning is to gain knowledge from data. machine learning depends on various algorithms to address data challenges. it's important to note that there isn't a universal algorithm that suits all problems; the choice of algorithm depends on factors such as the problem type, the number of variables involved, and the most suitable model. let's briefly explore the ml algorithms employed in this research [12].  random forest a random forest (rfc) is an ensemble machine learning approach used for predictive modeling, suitable for both classification and regression tasks. it combines the outcomes from various decisions made by different decision trees. the last stage is done by the determination of the veryfication of the mode (most frequent value) for classification or mean prediction from these trees for regressive. the process gets on by splitting the data set into the training set and test set, then selecting the entire samples randomly from the training set. each of these categories uses a decision tree to break the divisions with the goal of accurate segmenting of data points into groups or predicting values. this is sequential firstly picking up samples and then making decisions trees. then the random forest combines the individual predictions of all the decision trees and finally it conducts a majority vote. those predictions that have the majority of votes are actually the final output values [12].  support vector classifier svc ( support vector classifiers ) which is a support vector is the most widely-used system in machine learning. in the context of machine learning, support vector classifiers are supervised learning models having an algorithm which analyses the data to perform the classification and regression analysis functions. progressing from their competency to execute linear classification, svcs has come to exhibit non-linear classification through the procedure of “the kernel trick.” this method produces the necessary k-dimensional feature spaces that mark particular classes based on typical features associated with each class. while the design is complex and sensitive to the balance between accuracy and coverage, each boundary is passed through with the aim of minimizing the distance between them and the separate classes to prevent misclassification errors [13].  k-nearest neighbor the k-nearest neighbors method (knn) belongs to the supervised learning category that is, into the class of classification. knn stands for the nearest neighbors algorithm that uses all data available and is insensitive to noise by evaluating similarity. through a measurement of two parameters in a two dimensional cartesian plane, we can establish the similarity of the points on the plane based on the distance between them. on the same wavelength, knn works based on the law that the similar things usually stay close to each other.[14]  logistic regression logistic regression (lr), being a statistical method that uses logistic function as its core unit. though there are advanced derivations of this model, its ultimate usage is to calculate the probability of either a binary dependent variable. the logistic regression model itself doesn't carry out statistical classification – it's not a classifier per se. however, it can be adapted for classification tasks. one common technique is to establish a threshold value and categorize inputs based on whether their predicted probabilities surpass or fall below this threshold. this method is widely adopted for constructing binary classifiers. logistic regression finds applications in various domains such as fraud detection, clinical trials, and scenarios where outcomes are binary [13].  xgboost xgboost (xgb) is a highly efficient gradient tree boosting technique that creates a sequence of decision trees. it excels at swiftly carrying out relevant computations across various computational setups. consequently, xgboost is widely favored for its capability to model new features and make classifications. the utilization of the xgboost algorithm has surged in popularity, mainly owing to its integration with tabular and structured datasets [15]. 2.1 gathering data as previously mentioned, machine learning algorithms undergo training using existing datasets to enhance their performance. the effectiveness of these models relies significantly on the size and quality of the training data. the initial phase of the machine learning workflow involves identifying, collecting, or in some instances, generating the training dataset. the specific approach taken in this regard is heavily influenced by the desired noor a. mohammed al-khwarizmi engineering journal, vol. 20, no.2, p.p. 2638(2024) 30 objectives of the model under development. to gain practical experience in executing the various stages of a machine learning workflow, we employed datasets obtained from sensors monitoring a universal ac motor. these datasets encompass normal operating conditions, fault scenarios, and include a motor with bidirectional rotation capability as well as a rapid motor stop feature. table 1 shows the size and counts of data sets for each classification, while table 2 shows samples of the data collected. table 1, size and counts of data sets for each classification [16] failure type file size (kb) count of data no failure 654.3 11996 vibration failure 316.1 5946 over current failure 550.7 10092 bush failure 157.7 2910 stop rotating failure 254.6 4656 table 2, sample of data collected [16] accel x (1g) accel y (1g) accel z (1g) amb_temp (oc) object_temp (oc) current (amp.) failure type 1 3.656 -1.125 -7.156 22.35 51.69 0.586 no failure 2 0.593 -0.625 -7.187 22.38 51.53 0.587 no failure 3 -2.5 0.593 -6.687 22.36 51.61 0.610 no failure 4 2.781 -1.281 -6.812 22.36 51.63 0.519 no failure 5 2.156 -0.687 -7.343 22.38 51.49 0.558 no failure 6 -2.25 1.062 -6.937 22.36 51.67 0.606 no failure 7 -1.906 0.687 -1.406 22.88 53.03 0.569 vibration failure 8 4.781 -1.562 -8.031 23.15 55.35 1.339 over current failure 9 0.718 -0.406 -6.875 23.81 65.53 1.041 bush failure 10 -16 -16 -11.375 23.74 54.89 0.672 stop rotating failure 2.2 outliers inspection the goal of this section is to check if the dataset contains any outliers, which are usually misleading for machine learning algorithms. we start by examining a statistical analysis of the numerical characteristics. it is possible to infer the potential existence of outliers in both the x-axis acceleration and object temperature due to the substantial disparity between the maximum value and the third quartile. to provide a clearer perspective on this, we delve deeper into the data using boxplots to gain insights into the distribution, as illustrated in figure 1, however, in the case of acceleration in xaxis, there are probably traceable outliers to the way outliers are detected using boxplots. in the case of object temperature, the gaussian distribution is skewed and it is not unrealistic to think that the few observations with medium object temperatures are going to fail. as a result, the outliers were retained and reserved the discretion to determine whether to take any action on them after evaluating other factors. noor a. mohammed al-khwarizmi engineering journal, vol. 20, no.2, p.p. 2638(2024) 31 fig. 1. numeric features boxplots. 2.3 resampling with smote resampling with the synthetic minority oversampling technique (smote) is an important consideration considering the extremely low occurrence of machine failures among the entire dataset. when addressing machine learning challenges, the issue of class imbalance becomes a significant concern. this imbalance can distort both the training process of models and our ability to interpret their outcomes. for instance, if we create a model using a dataset that predicts machines will never malfunction, it might seem accurate on the surface. to mitigate these issues and minimize biased model behavior toward specific classes, we employ data augmentation. the goal is to achieve an 80-20 ratio between functioning and faulty observations, along with an equal occurrence percentage among the various failure causes. the smote procedure operates as follows: it randomly selects a subset from the minority class and identifies the k nearest neighbors for each observation in this subset. next, it selects one of these neighbors and calculates the vector connecting the current data point to the chosen neighbor. this vector is then scaled by a random value ranging from 0 to 1. the synthetic data point is generated by adding this scaled vector to the current data point. the result of resampling is shown in figure 2. fig. 2. causes involved in machine failures. noor a. mohammed al-khwarizmi engineering journal, vol. 20, no.2, p.p. 2638(2024) 32 2.4 metrics to evaluate the models, we used from a quantitative point of view, some metrics that summarized some characteristics of the classification results: accuracy: expresses the fraction of instances that are classified correctly; it is the most intuitive metric that is usually used in classification tasks [17]. 𝐴𝑐𝑐𝑢𝑟𝑎𝑐𝑦 = tp+tn tp+tn+fp+fn …(1) where: true positive (tp): when both the actual and predicted values are 1. true negative (tn): when both the actual and predicted values are 0. false positive (fp): when the actual value is 0 but the predicted value is 1. false negative (fn): when the actual value is 1 but the predicted value is 0. auc: can be considered as a measure of the separation between true positives and true negatives, that is, the ability of the model to distinguish between classes. f1: reports the classification capacity of the model to precision and recall, giving both the same weight. [17] 𝐹1 = 2∗ precison∗recall precision+recall … (2) where: 𝑃𝑟𝑒𝑐𝑖𝑠𝑖𝑜𝑛 = tp tp+fp … (3) 𝑅𝑒𝑐𝑎𝑙𝑙 = tp tp+ fn … (4) although generally effective, auc can be optimistic in the case of highly unbalanced classes, as happens in the binary task, while the f1 score is more reliable in this kind of scenario. we consider this last metric particularly significant as it is able to mediate the cases in which the machines that are about to fail are classified as functioning (recall) and the ones in which functioning machines are classified as about to suffer a failure (precision). to be more specific, we gave more importance to recall than precision by evaluating an "adjusted" version of the f1 through a β parameter [17]: 𝐹𝛽 = (1 + 𝛽2) precison∗recall 𝛽2 precision+recall … (5) with the choice β=2 (common in literature) a greater influence of the recall is obtained. the decision to limit unnecessary replacement material purchases is driven by the goal of optimizing machinery maintenance costs. however, it is even more crucial to prevent machinery breakdowns, as they typically entail higher expenses, outweighing the savings from reducing replacement material purchases. figure 3 shows a flowchart that summarizes the main steps used in predicting failures in ac motors using machine learning algorithms. fig. 3. flowchart of a proposed approach. 3. results and discussion 3.1 binary task the goal of this section was to find the best model for binary classification of the dataset to predict whether or not there was machine failure. classification algorithms, a key component of data mining, employ supervised machine learning techniques to forecast data outcomes. they operate by utilizing a pre-labeled dataset containing multiple classes or categories, constructing a classification model based on this input, and subsequently applying it to new, unlabeled data to determine their respective class assignments. typically, the initial dataset is partitioned into three sets: the training set, used for model training; the validation set, employed to fine-tune model parameters and assess its performance on the training data; and the test set, reserved for evaluating the model. in our study, we adopted a split ratio of 80% of each failure type count of data mentioned in table 1 for training, 10% for noor a. mohammed al-khwarizmi engineering journal, vol. 20, no.2, p.p. 2638(2024) 33 validation, and 10% for testing. our experimentation revealed that this partitioning strategy yielded the optimal results among the various strategies we considered. all of the chosen models achieved comparable results on the validation set, as depicted in table 3. it is challenging to ascertain the superiority of one model over another based solely on these values. moreover, the performance remained consistent when evaluated on the test set, as demonstrated in table 4, indicating that overfitting was successfully mitigated. in order to fully verify the robustness of the ac motor, the state of the ac motor was predicted by examining the confusion matrices and the metrics showcased in figures 4 and 5. the horizontal axis is the label corresponding to the predicted state and the vertical axis is the label corresponding to the actual state. this approach helps to elucidate a hierarchical ranking among the utilized models, as the metrics for each model consistently either outperform or underperform compared to the others, while the parameter search time remains similar. all models (lr, knn, xgb svc, and rfc) achieved extremely similar results, but the training time is varied as shown in table 5. in particular rfc obtains the worst training times and knn the best ones. table 3, validation scores of a binary task lr knn svc rfc xgb acc 0.999 0.999 0.999 1.0 0.999 auc 1.0 1.0 1.0 1.0 1.0 f1 0.998 0.998 0.998 1.0 0.998 f2 0.999 0.999 0.999 1.0 0.997 fig. 4. validation set confusion matrices of a binary task table 4, test scores of a binary task lr knn svc rfc xgb acc 1.0 1.0 1.0 1.0 1.0 auc 1.0 1.0 1.0 1.0 1.0 f1 1.0 1.0 1.0 1.0 1.0 f2 1.0 1.0 1.0 1.0 1.0 fig. 5. test set confusion matrices of a binary task. noor a. mohammed al-khwarizmi engineering journal, vol. 20, no.2, p.p. 2638(2024) 34 table 5, training time for each algorithm of a binary task machine learning algorithms training time (sec) lr 8 knn 4 svc 34 rfc 151 xgb 83 3.2 multi-class task the second task of this work was to predict not only if there would be a failure but also the type of failure that occurred. so, we were dealing with multiclass classification problems, assuming that each sample was assigned to one and only one label. this hypothesis was verified because, in data preprocessing, we removed all the ambiguous observations that belonged to more than one class. for multiclass targets, when we calculated the values of auc, f1, and f2 scores in tables 6 and 7, we needed to set the parameter 'average.' we chose 'average=weighted' to account for class imbalance. in fact, at the end of data preprocessing, we had 80% working machines and 20% that failed. as for the binary classification task, we adapted the models developed in the previous section. while many classification algorithms (such as 'random k-nearest neighbor,' 'random forest,' and 'xgboost') naturally permitted the use of more than two classes, some (like logistic regression and support vector classifier) were by nature binary algorithms. however, these could be turned into multiclass classifiers using a variety of strategies. for our work, we decided to train a single classifier per class, with the samples of that class as positive samples and all other samples as negatives. we chose this because it was computationally more efficient than other types of approaches. for each model, we launched the grid search for hyperparameter optimization, using the weighted average f2 score as the metric to evaluate the model. by comparing the results obtained, we saw that all models obtained high values for the chosen metrics both for the validation and test sets, as shown in figures 6 and 7. if we look at the training time, knn took the shortest time, while xgb took a very long time, as shown in table 8. so, one could choose the knn model according to their needs. table 6, validation scores of a multi-class task lr knn svc rfc xgb acc 0.999 0.999 0.999 1.0 0.999 auc 1.0 1.0 1.0 1.0 1.0 f1 0.999 0.999 0.999 1.0 1.0 f2 0.999 0.999 0.999 1.0 1.0 fig. 6. validation set confusion matrices of a multi-class task. noor a. mohammed al-khwarizmi engineering journal, vol. 20, no.2, p.p. 2638(2024) 35 table 7, test scores of a multi-class task lr knn svc rfc xgb acc 1.0 1.0 1.0 1.0 1.0 auc 1.0 1.0 1.0 1.0 1.0 f1 1.0 1.0 1.0 1.0 1.0 f2 1.0 1.0 1.0 1.0 1.0 fig. 7. test set confusion matrices of a multi-class task. table 8, training time for each algorithm of a multi-class task machine learning algorithms training time (sec) lr 10 knn 3 svc 53 rfc 139 xgb 276 3. conclusions in this research work, datasets pertaining to the condition monitoring of ac motors was utilized to assess the effectiveness of various machine learning techniques within a practical predictive maintenance (pdm) context. we employed five different machine learning algorithms, namely “random forest (rfc)”, “support vector classifier (svc)”, “k-nearest neighbors (knn)”, “logistic regression (lr)”, and “xgboost (xgb)”, to predict potential machine failures. additionally, we conducted a comparative analysis of these algorithms. our approach involves training these algorithms using datasets of varying sizes and subsequently evaluating their accuracy on test data. this evaluation was conducted in relation to the size of the training data, allowing us to investigate how the training set size impacts algorithm performance. the main contribution of this paper compared to other related works is developing a pdm method using five machine learning algorithms that can not only monitor the state of the ac motor in real-time but also predict the fault of the ac motor in advance. the outcomes of our analyses and the resulting findings enable us to draw meaningful conclusions regarding this research project. two primary objectives were understood: firstly, to predict machine failure, and secondly, to forecast the specific failure type. prior to constructing our models, we engaged in comprehensive data preprocessing to validate model applicability assumptions and optimize performance. in this preprocessing phase, we removed certain ambiguous samples, performed label encoding on categorical columns, and applied column scaling. additionally, we initially identified some data points as outliers, which, upon further examination, were revealed to be intrinsic to the data's natural variability and played a significant role in the classification task. consequently, we determined that these features had the most substantial impact on predictions when applying the models. interestingly, our findings, according to the case of the ac motor, demonstrated that the machine's type did not influence the occurrence of failures. we can conclude that for both task the models are the same in their performance, and the only difference is the training time. for both tasks the best model is knn, and the worst is svc for binary task, and xgb for multi-class task according to the response noor a. mohammed al-khwarizmi engineering journal, vol. 20, no.2, p.p. 2638(2024) 36 time. the choice of the model depends on the needs of the company; for faster application, one can use knn. further, there are more challenges to be considered in future research, such as the ability to predict unknown faults, which needs to be optimized. future research can be extended to the use federated learning between many ac motors that is dynamic in client sample sizes, client distributions, and the client set as a whole. symbols and abbreviations auc accuracy fn false negative fp false positive knn k-nearest neighbors lr logistic regression ml machine learning nb naive bayes pdm predictive maintenance rfc random forest smote synthetic minority oversampling technique svc support vector classifier tn true negative tp true positive ttf time to failure xgb xgboost references [1] pech, m.; vrchota, j.; bednář, j. predictive maintenance and intelligent sensors in smart factory: review. sensors 2021, 21, 1470. https://doi.org/10.3390/s21041470 [2] andreas, t.; judith, p.; marcel, k.; gordon, e. predictive maintenance enabled by machine learning: use cases and challenges in the automotive industry. reliability engineering & system safety 2021, 215, 107864. https://doi.org/10.1016/j.ress.2021.107864 [3] onur, s.; stephen, a.; john, y. condition monitoring using machine learning: a review of theory, applications, and recent advances. expert systems with applications 2023, 221, 119738. https://doi.org/10.1016/j.eswa.2023.119738 [4] [4] rojek, i.; jasiulewicz kaczmarek, m.; piechowski, m.; mikołajewski, d. an artificial intelligence 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hamad, a.h. performance evaluation of sdn ddos attack detection and mitigation based random forest and k-nearest neighbors machine learning algorithms. revue d'intelligence artificielle 2022, 36, 2, 233-240. https://doi.org/10.18280/ria.360207 [15] jian, f.; hongbin, w.; fan y.; kuang, y.; xiang, l.; min, z. a failure prediction method of power distribution network based on pso and xgboost. australian journal of electrical and electronics engineering 2022, 19, 4, 371378. https://doi.org/10.1080/1448837x.2022.2072 447 [16] mohammed, n.a.; abdulateef, o.f.; hamad, a.h. an iot and machine learning-based predictive maintenance system for electrical motors. journal européen des systèmes automatisés 2023, 56, 4, 651-656. https://doi.org/10.18280/jesa.560414 [17] jérôme, d.; gaël, v.; jean-baptiste, p.; preventing dataset shift from breaking machine-learning biomarkers. gigascience 2021, 10, 9. https://doi.org/10.1093/gigascience/giab055 https://doi.org/10.1093/gigascience/giab055 (2024) 26-38، صفحة 2، العدد20مجلة الخوارزمي الهندسية المجلد محمد نور علي 38 تحليل أداء خوارزميات التعلم اآللي المختلفة للصيانة التنبؤية ****عدي إبراهيم عبد هللا ،***علي حسين حمد، **سامة فاضل عبد اللطيفأ ،*محمد نور علي العراق ،بغداد ،جامعة بغداد ،كلية الهندسة الخوارزمي ،قسم هندسة التصنيع المؤتمت *،** العراق ،بغداد ،جامعة بغداد ،كلية الهندسة الخوارزمي ،المعلومات واألتصاالت قسم هندسة *** ألمانيا ،21079هامبورغ ،ي جامعة هامبورغ للتكنولوج ، تقنيات النظام ومنهجية التصميم الهندسي ***** noor.ali2204@kecbu.uobaghdad.edu.iq:البريد اإللكتروني * drosamah@kecbu.uobaghdad.edu.iq:البريد اإللكتروني** ahamad@kecbu.uobaghdad.edu.iq:البريد اإللكتروني*** oday.abdullah@tuhh.de:البريد اإللكتروني**** المستخلص يركز البحث وتردد. يقدم هذا العمل دراسة شاملة عن تقييم أداء خوارزميات التعلم اآللي المختلفة للصيانة التنبؤية في سياق مراقبة حالة محرك التيار الم يتم وكل من حدوث األعطال ونوع الفشل المحدد في محركات التيار المتردد. في على سيناريوهات واقعية لتقييم قدرات الخوارزميات المختلفة في التنبؤ k-nearest neighbors(، وsvc) support vector classifier(، وrfc) random forestاستخدام خمس خوارزميات بارزة للتعلم اآللي، وهي (knn( واالنحدار اللوجستي ،)lrو ،)gboost (xgb في هذا العمل. يتضمن ،) التقييم تحليًلا مقارناا لهذه الخوارزميات بناءا على دقتها التنبؤية، مع يتم تطبيق تقنيات معالجة مسبقة صارمة للبيانات لضمان صحة افتراضات النموذج وتحسين األداء. ومجموعات تدريب بأحجام مختلفة. قبل تطوير النموذج، ة، وترميز األعمدة الفئوية باستخدام ترميز الملصقات، وقياس األعمدة. ومن المثير لًلهتمام، إعادة تتضمن مرحلة المعالجة المسبقة إزالة العينات الغامضو لوحظ وم التصنيف. النظر في تحديد نقاط البيانات التي تبدو غريبة، مما يكشف عن دورها األساسي في التقاط التباين الطبيعي لمجموعة البيانات وتعزيز مها يوضح العمل أنه بالنسبة للتنبؤ بفشل اآللة وتحديد أنواع الفشل، فإن الخوارزميات تظهر وة هي مساهمات محورية في النماذج التنبؤية. أن هذه الميزات المحدد ا. النموذج األفضل أداءا وصفها( باستمرار بknn) k-nearest neighborsتبرز خوارزمية أذيكمن االختًلف األساسي في وقت التدريب، وأداءا مشابها ثانية(. ( في مهام التنبؤ بالفشل الثنائي، 151تدريب )لل( أسوأ وقت rfc) random forestثواٍن( على التوالي، بينما تؤدي 3ثواٍن و 4لكًل المهمتين ) تام، تؤكد هذه الورقة أهمية ثانية(، والتي تعزى إلى أوقات االستجابة الخاصة بها. في الخ 276( في مهام التنبؤ بالفشل متعددة الفئات )xgb) xgboostو ترميتوفر النتائج رؤى قيمة للشركات التي واختيار نماذج التعلم اآللي المناسبة للصيانة التنبؤية، مع األخذ في االعتبار المفاضلة بين الدقة ووقت التدريب. ل للتطبيق السريع.كخيار مثا knnة والفعالية، مع ظهور يإلى تنفيذ استراتيجيات صيانة تنبؤية تتسم بالكفا mailto:drosamah@kecbu.uobaghdad.edu.iq mailto:ahamad@kecbu.uobaghdad.edu.iq mailto:oday.abdullah@tuhh.de this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 20, no. 1, march, (2024), p. p. 116 modification, characterization of tea residue-derived activated carbon, and ciprofloxacin adsorption alaa kareem mohammed* israa m. rashid** nadya hussin al sbani*** wan nor roslam wan isaha**** *,**department of biochemical engineering / al-khwarizmi college of engineering/ university of baghdad/ baghdad / iraq ***department of chemical engineering/ faculty of oil and gas engineering/ al zawia university/ libya ****department of chemical and process engineering/ faculty of engineering and built environment/ universiti kebangsaan malaysia/ 43600 ukm bangi/ selangor/ malaysia corresponding author*email: dr.alaa@kecbu.uobaghdad.edu.iq **email: israa msc2018@kecbu.uobaghdad.edu.iq ***email: n.alsbani@zu.edu.ly ****email: wannorroslam@ukm.edu.my (received 29 august 2023; accepted 6 november 2023; published 1 march 2024) https://doi.org/10.22153/kej.2024.11.001 abstract tea residue was used for preparing activated carbon (ac) which was used as an adsorbent to remove ciprofloxacin (cip) from synthetic contaminated water. this study investigates the physicochemical properties and adsorption efficiency of the prepared activated carbon. the activated carbon was prepared via two steps: activation step using phosphoric acid (h3po4) followed by carbonization at a temperature of 450 °c. different factors were investigated to show their effects on the adsorption efficiency of (cip). these factors were initial concentration of (cip), ph, absorption time, and adsorbent dosage. the maximum adsorption efficiency was 94.4% which was obtained when ph=8.75, contact time =454 min, adsorbent dosage =0.194 g/ 25 ml, and initial concentration of 200 ppm. the prepared activated carbon was characterized using fourier transform infrared spectroscopy (ftir), scanning electron microscopy (sem), x-ray diffraction (xrd), and brunauer-emmett-teller (bet). the prepared activated carbon was found to have a specific surface area of 774 m2/g. it was found that the langmuir model well fit the adsorption isotherm of (cip) on the prepared activated carbon. the produced activated carbon can adsorb ciprofloxacin, with a maximum adsorption capacity of 256.41 mg g-1. a pseudo-second-order reaction model is effective at describing the kinetics of adsorption. the examination of adsorption thermodynamics reveals that the process of cip adsorption on tac is characterized by being both endothermic and spontaneous. keywords: adsorption, tea residue, active carbon, ciprofloxacin, adsorption kinetics, adsorption thermodynamics. 1. introduction water is essential to human life and the health of the environment. its existence is described as a limiting factor for human development. the growing population demands more water for a wide range of uses while water resources are limited. in addition to that, the rapid increase in industrial and human activities produces increasing amounts of waste matter as well as a higher spread of environmental water pollution [1]. pollution, in its broadest sense, includes all changes that restrict natural functions and exert damaging effects on life [2]. water pollution is the undesired change in water quality that leads to an unfavorable alteration of the physical, chemical, and biological properties of water that prevents domestic, commercial, industrial, agricultural, recreational, and other beneficial uses of water [3], [4]. there are various types of water pollutants; they are mainly mailto:dr.alaa@kecbu.uobaghdad.edu.iq mailto:israa%20msc2018@kecbu.uobaghdad.edu.iq mailto:n.alsbani@zu.edu.ly mailto:wannorroslam@ukm.edu.my mailto:wannorroslam@ukm.edu.my https://doi.org/10.22153/kej.2024.11.001 alaa kareem mohamme al-khwarizmi engineering journal, vol. 20, no. 1, p.p. 116(2024) 2 categorized into organic pollutants (e.g., petroleum hydrocarbons, aromatic hydrocarbons, organic halides, oils, dyes, etc.), and inorganic compounds (e.g., mineral acids, inorganic salts, trace elements, metal compounds, cyanides, sulfate, heavy metals, etc. [5], [6]. veterinary medicine, human medicine, and the pharmaceutical industries are the principal contributors of pharmaceutical residues to the environment. in addition, when therapeutic compounds are discharged from factories, hospitals, and private homes or when unwanted pharmaceuticals are improperly disposed of, surface water and groundwater are contaminated, and drinking water is contaminated as a result. this poses a potential health risk to humans [7]. as a result, many treatment technologies have been proposed to treat this type of wastewater, such as reverse osmosis, ion exchange, adsorption, and nanofiltration [8]. among these methods, the adsorption process is regarded as a promising method for the removal of micropollutants because of its simple design, low cost, high efficiency, and low production of toxic intermediates [9]. due to antibiotics' toxicological effects on aquatic species and the resistance they can create in some bacterial strains, even at low concentrations, the presence of antibiotics in surface water and wastewater has been regularly reported and is growing in importance. [10]. ciprofloxacin (cip; c17h18o3n3f) is efficient against several different gram-negative and grampositive bacteria [11]. cip is frequently detected in groundwater and polluted wastewater as a result of its widespread use to treat several human and animal illnesses. [12]. figure 1 shows the basic structure of cip. fig. 1. structure of ciprofloxacin. several adsorbents, as cheap and efficient alternate materials, have been used, such as activated carbon, graphene, and silica, for water purification [13], [13]. a wide range of inorganic and organic pollutants are removed from the aquatic environment and industrial wastewater using activated carbon as an efficient adsorbent due to its high surface area, porosity structure, the presence of a broad spectrum of surface functional groups, and the capability of pollutant distributed on the high internal surface [14]. activated carbon is widely used as an adsorbent due to its features such as low cost, availability, and surface heterogeneity [15]. therefore, the practical usage of ac is restricted by the price of precursors and relatively high preparation costs [16]. biomass waste as a renewable resource has attracted widespread attention. aiming to reduce the total cost regarding the preparation of ac, using biomass waste as a precursor of ac, including groundnut husks [17], sugarcane bagasse [18], coconut shells [19], and tea residue [20], [21], is a viable option. apart from the precursors, the physicochemical property of ac is also associated with the preparation method. the preparation of ac is divided into the following two methods, i.e., chemical activation and physical activation [22]. typically, the activation temperature for lignocelluloses, precursors of ac, is between 800 and 1000 °c. during the chemical activation stage, acid, alkali, and salt, such as phosphoric acid (h3po4) [20], potassium hydroxide (koh) [15], and zinc chloride (zncl2) [23], are often employed as activating agents. activating temperature, impregnation ratio, and activation time[24], [25] are some of the factors that affect the physicochemical properties of ac during the chemical activation process. this study was concerned with the feasibility of using tea residue as a low-cost and readily available sorbent material for the removal of ciprofloxacin from aqueous solutions in batch mode. tea residue was selected as a precursor to prepare activated carbon using chemical activation with h3po4. the adsorption of ciprofloxacin was also looked at to find out about the adsorption equilibrium, kinetics, and thermodynamics of the ac sample that was made. 2. materials and methods 2.1 materials the tea residue was collected locally from leftover tea used in homes. ciprofloxacin (cip) was chosen as the target adsorbate and supplied by the ministry of health, iraq. ciprofloxacin was directly used without any further treatment. phosphoric acid (h3po4), used as the activating agent, was purchased from himedia, india. alaa kareem mohamme al-khwarizmi engineering journal, vol. 20, no. 1, p.p. 116(2024) 3 2.2 preparation of activated carbon the waste tea was boiled with distilled water for 2 hours to remove water-soluble materials and then washed with distilled water until the washing water was colorless. the decolorized waste tea was dried in a drying oven at 110 °c for 10 hours. before activation, the waste tea was fully mixed with a 60% (by wt) h3po4 solution at an impregnation ratio of 1:2.5 (g waste tea /g h3po4) at room temperature for 12 hours. the mixture was then filtered. after pretreatment, the raw material was placed in a closed steel crucible for carbonization in a furnace at 450 °c for 1 hour with nitrogen. the n2 flow is 150 cm3/min. after cooling to room temperature, the activated carbon was washed with distilled water (dw) until ph equaled seven. then the carbons were dried at 110 °c for 6 hours. the product (tac) was ground with mortar and sieved to obtain a particle size equal to or less than 350 µm then preserved in a desiccator for the upcoming batch trials. 2.3 activated carbon characteristics various characterizations were performed to describe the adsorbent produced. scanning electron microscopy (sem) was used to analyze the surface morphologies (joel, jsm-7600 f, tokyo, japan). fourier transform infrared spectroscopy (ftir 8400s shimadzu) was used to study the functional groups on the adsorbent surface using kbr pellets in the (4000-400 cm-1) range. x-ray diffraction (xrd) was used to determine the crystalline phase (type shimadzu xrd 6000 / japan). the elemental composition of the absorbent was studied using edx (joel, jsm7600 f, tokyo, japan). the brunauer-emmettteller (bet) analysis (horiba, sa-900 series, usa), to determine the surface area and porous structure of activated carbon. 2.4 ciprofloxacin adsorption on tac at room temperature, batch adsorption experiments with 50 ml of ciprofloxacin (cip) solution were carried out at different initial concentrations (100–500 mg/l), ph (2–11), contact time (15-600 min), and active carbon (tac) dosage (0.025–0.25 g/25 ml) at a constant speed of agitation (150 rpm). in the erlenmeyer flask (250 ml), 50 ml of cip solution of the specified initial concentration was put in. the tac was added with a known quantity and mixed well at 150 rpm using an orbital shaker(edmund buhler sm25, german). after that, the adsorbent was removed from the aqueous solution using filter paper (whatman). the final cip concentration was measured using a double-beam uv-visible spectrophotometer (pg instruments, model uv t80, england). the cip has a wavelength of 272.5 nm. the proportion of cip removed by the prepared activated carbon (tac) was calculated using eq. (1) [26]. 𝑹 % = [ 𝑪₀ − 𝑪𝒆 𝑪₀ ] ∗ 𝟏𝟎𝟎% … (𝟏) where r represents the removal percentage, 𝐶𝑜 & 𝐶𝑒 are initial and equilibrium concentrations of cip (mg/l) respectively. the adsorption capacity at equilibrium qₑ was calculated using eq.(2) [27], [28]. 𝒒ₑ = (𝑪₀ − 𝑪𝒆)𝑽 𝒎 … (𝟐) where v(ml) is the sample volume and m (g)is the adsorbent quantity. 2.5 design of an adsorption experiment the central composite design (ccd) was used in the experimental design with four variables at five levels. these variables were: adsorption time, solution acidity ph, adsorbent dosage, and cip initial concentration co. these variables were studied to investigate their impact on the adsorption efficiency of cip. to design, analyze, and optimize the influencing parameters as well as to create an empirical model illustrating the cip's adsorption efficiency, experimental design software (ccd) was employed. the independent factors, with their actual levels and coding chosen for process optimization, are shown in table 1. alaa kareem mohamme al-khwarizmi engineering journal, vol. 20, no. 1, p.p. 116(2024) 4 table 1, adsorption experimental design following ccd the effects of the parameter on cip sorption were modeled and designed using the ccd method, as illustrated in table 1. the time for absorption (𝑋1), ph (𝑋2), dose of the adsorbent (𝑋3), and cip's initial concentration (𝑋4) were used to optimize the response removal of cip (r%). the value of the coefficient of determination r2 was used to assess the fit of the regression, eq. (3), and it was found to be 0.9997, approving the model's accuracy. 𝑅 = 80 + 3.11 𝑋1 + 0.3846 𝑋2 + 2.94𝑋3 − 3.2 𝑋4 + 1.22 𝑋1𝑋2 − 0.6994 𝑋1𝑋3 − 1.66 𝑋1𝑋4 − 0.1394 𝑋2𝑋3 − 1.44 𝑋2𝑋4 + 0.1069 𝑋3𝑋4 + 0.7178 𝑋1 2 + 0.2216 𝑋2 2 + 0.3016 𝑋3 2 + 0.1628 𝑋4 2 … (3) figure 2 plots the predicted vs. observed values of removal percent content in the five-factor ccd analysis. the predicted responses from the empirical function are almost identical to the measured values, where all points are close to the line in the range of the operating factors. fig. 2. predicted vs. actual values of the percentage removal of cip adsorption. 3. results and discussion 3.1 characterization of the activated carbon 3.1.1 characterization using ft-ir the chemical structure of the carbon substance is revealed through infrared spectroscopy. figure 3 60 65 70 75 80 85 90 95 100 60 65 70 75 80 85 90 95 100p re d ic te d r em o v al % actual removal % run x1: adsorption time (min) x2: ph x3: dosage (g/25ml) x4:sa initial conc. (mg/l) r% (experimental) r% predicted residuals 1 307.5 6.5 0.1375 100 86.86 87.05 -0.1854 2 161.25 8.75 0.08125 200 77.1 77.05 0.0529 3 453.75 8.75 0.08125 400 77.6 77.61 -0.0137 4 161.25 4.25 0.19375 200 83 82.91 0.0913 5 307.5 6.5 0.1375 300 80 80 0 6 307.5 6.5 0.1375 500 74.2 74.26 -0.0571 7 161.25 8.75 0.19375 400 78 78.09 -0.0887 8 161.25 4.25 0.19375 400 83 82.92 0.0792 9 453.75 4.25 0.08125 400 77 77 -0.0008 10 453.75 4.25 0.19375 400 82 81.98 0.0246 11 307.5 6.5 0.25 300 87 87.09 -0.0871 12 161.25 4.25 0.08125 200 75.6 75.56 0.0358 13 307.5 2 0.1375 300 80 80.12 -0.1171 14 15 6.5 0.1375 300 76.5 76.66 -0.1604 15 161.25 8.75 0.19375 200 84 83.83 0.1658 16 453.75 8.75 0.19375 400 82.16 82.03 0.1292 17 161.25 8.75 0.08125 400 71.03 70.87 0.1558 18 453.75 8.75 0.08125 200 90.5 90.41 0.0858 19 600 6.5 0.1375 300 89 89.08 -0.0821 20 307.5 6.5 0.025 300 75.17 75.33 -0.1554 21 453.75 8.75 0.19375 200 94.4 94.41 0.0063 22 161.25 4.25 0.08125 400 75.22 75.15 0.0713 23 453.75 4.25 0.19375 200 88.6 88.59 0.0092 24 453.75 4.25 0.08125 200 84.21 84.04 0.1663 25 307.5 6.5 0.1375 300 80 80 0 26 307.5 6.5 0.1375 300 80 80 0 27 307.5 11 0.1375 300 81.53 81.66 -0.1254 alaa kareem mohamme al-khwarizmi engineering journal, vol. 20, no. 1, p.p. 116(2024) 5 shows the ftir spectra of the synthetic carbons obtained by phosphoric acid activation at different concentrations. a broad transmittance band is visible in all spectra between 3200 and 3600 cm-1, with maxima at roughly 3420 to 3440 cm-1. the oh stretching mode of the hydroxyl groups and the adsorbed water can be attributed to this band. all carbons' spectra have a faint, acute transmittance band between 2921 and 2855 cm-1, which decreases when carbons are exposed to high concentrations of h3po4 [29]. the spectral bands shown in figure 3 at wavenumbers 885, 840, and 775 cm-1 can be attributed to the out-of-plane deformation mode of the c-h bonds in different substituted benzene rings. the spectral feature observed at approximately 1700 cm-1 is commonly attributed to the stretching vibrations of c-o bonds in ketones, aldehydes, lactones, or carboxyl groups. the activated carbons that were synthesized exhibit a prominent spectral feature in the range of 16001580 cm-1, which can be attributed to the vibrations of carbon-carbon bonds inside aromatic rings. the spectral peak observed at the wavenumber range of 1190-1200 cm-1 has been attributed to the stretching mode of hydrogen-bonded p=o, as well as the stretching vibrations of o-c bonds in p-o-c (aromatic) linkages. additionally, this peak is also associated with the presence of p=ooh. this assignment is supported by reference [30]. in summary, the analysis of impregnation in infrared spectroscopy (ir) reveals significant alterations, notably the introduction of phosphorous groups (at a wavenumber of 1100 cm1) and the emergence of c-h vibrations. the latter can be attributed to the depletion of oxygen at the carbon material's surface. fig. 3. ftir spectra of the raw material, tea residue, and tea active carbon tac. 3.1.2 characterization using sem the prepared active carbon's ( tac ) form and surface morphology were investigated using sem and edx analysis, as illustrated in figure 4. figure 4a which illustrates the micro-surface morphologies of (tac). the activated carbon depressions exhibit internal structures characterized by the presence of cavities and cracks on their external surfaces. the presence of holes on carbon surfaces can be attributed to the evaporation of the activating agent, phosphoric acid, during the carbonization process. this evaporation leads to the creation of voids in the areas formerly occupied by the agent. [31]. the h3po4 impregnation, followed by a heat treatment in an inert environment, affects the microstructure of activated carbon. these effects will break down many of the bonds within the material and thus lose many of the components that make up the material, which will lead to an increase in pores within the material. the elemental analysis of activated carbon was conducted using energy-dispersive xray spectroscopy (edx), as shown in figure 4b, and indicates the existence of carbon at 69.66 %, oxygen at 16.89%, nitrogen at 12.06 %, and phosphorus at 1.48% alaa kareem mohamme al-khwarizmi engineering journal, vol. 20, no. 1, p.p. 116(2024) 6 fig. 4. (a) sem image of active carbon, (b) eds spectra of tac. 3.1.3 surface area and pore structure the results of the brunauer-emmett-teller (bet) research revealed that the activated carbon derived from tea residue (tac) exhibited a specific surface area of 774 m2/g and an average pore volume of 0.563 cm3/g. these results are consistent with the findings of tao et al. [15] who prepared activated carbon from tea residue and found the surface area and pore size fall in the range of 5031337 m2/g and 0.353-0.817 cm3/g, respectively. also, tuli et al. [32] found that the surface area and pore size of the activated carbon were 850.58 cm3/g and 0.67 cm3/g, respectively. 3.2 anova analysis table 2 presents the empirical outcomes of the analysis of variance (anova) assessments. the statistical significance of a parameter is indicated by its corresponding p-value. the model's f-value of 2592.2 and p-value of less than 0.0001 indicate that the model is statistically significant. in this case, 𝑋1, 𝑋2, 𝑋3, 𝑋4, 𝑋1 𝑋2, 𝑋1 𝑋3, 𝑋1 𝑋4, 𝑋2𝑋3, 𝑋2𝑋4, 𝑋3𝑋4, 𝑋1 2, 𝑋2 2, 𝑋3 2, and 𝑋4 2 are significant model terms. values greater than 0.05 indicate the model terms are not significant. the analysis results in table 2 indicate the significant effect of each variable in the model on removal efficiency. it can be observed that the initial concentration co parameter in the linear form 𝑋4 (f-value = 11012.55) has the most significant effect on removal efficiency, followed by the linear term of the mixing time 𝑋1 (f-value = 10390.10). in interactive terms, the most significant effective parameters are ph and initial concentration 𝑋2𝑋4 (f-value = 1488.12), and the other is mixing time and initial concentration 𝑋1𝑋4 (f-value = 1971.82), as well as mixing time and dosage 𝑋1𝑋3 (f-value = 1072.36). alaa kareem mohamme al-khwarizmi engineering journal, vol. 20, no. 1, p.p. 116(2024) 7 table 2, anova results of cip adsorption findings. an analysis of variance (anova) was employed to evaluate the appropriateness of the model. the quadratic model was found to be very significant, with the values of r-squared, adjusted r-squared, and predicted r-squared correlation coefficients equal to 0.9997, 0.9993, and 0.9981, respectively. this value indicates the proportionality of the experimental values and the predicted adsorption removal values. the anova analysis of cip adsorption nearly agrees with that of [7], who studied the removal of diclofenac from aqueous solution on apricot seeds using activated carbon synthesized by pyrocarbonic acid microwave and analyzed the results using the response surface methodology method. 3.3 interactions of adsorption parameters 3.3.1 ph and initial concentration of cip figure 5 shows the 3d response surface and contours of how the most important factors, ph and the initial concentration of cip, interact. the pvalue and f-value are indicators of these outcomes, as shown in table 2. figure 5 shows that the initial concentration is the most important factor in the adsorption process. in the range of the initial concentration of cip (co) between 100 and 500 ppm, the adsorption percentage increased with increasing ph. the observed phenomena can be attributed to the competitive interaction between cip and h+ ions for adsorption sites, occurring on the surface of the adsorbent under conditions characterized by low ph levels. the adsorbent exhibits a progressive increase in adsorption capacity as the ph level rises, eventually reaching its peak adsorption efficiency of 94.4% at a ph of 8.75 and an initial concentration of 200 ppm. nevertheless, when the ph is equal to 11, the adsorption capacity of tac fibers exhibits a little drop. this can be attributed to the weakening of hydrogen bonding caused by the presence of oh-1 ions. this behavior aligns with the findings of haotian et al., who conducted a study on the adsorption of tetracycline antibiotics. [33]. source sum of squares mean square f-value p-value model 808.4 57.74 2592.2 < 0.0001 significant 𝑿𝟏-time 231.45 231.45 10390.1 < 0.0001 significant 𝑿𝟐-ph 3.55 3.55 159.35 < 0.0001 significant 𝑿𝟑-dosage 207.51 207.51 9315.32 < 0.0001 significant 𝑿𝟒-co 245.31 245.31 11012.55 < 0.0001 significant 𝑿𝟏𝑿𝟐 23.89 23.89 351.32 < 0.0001 significant 𝑿𝟏𝑿𝟑 7.83 7.83 1072.36 < 0.0001 significant 𝑿𝟏𝑿𝟒 43.92 43.92 1971.82 < 0.0001 significant 𝑿𝟐𝑿𝟑 0.3108 0.3108 13.95 0.0028 significant 𝑿𝟐𝑿𝟒 33.15 33.15 1488.12 < 0.0001 significant 𝑿𝟑𝑿𝟒 0.1828 0.1828 8.2 0.0142 significant 𝑿𝟏² 10.99 10.99 493.46 < 0.0001 significant 𝑿𝟐² 1.05 1.05 47.01 < 0.0001 significant 𝑿𝟑² 1.94 1.94 87.09 < 0.0001 significant 𝑿𝟒² 0.5655 0.5655 25.39 0.0003 significant residual 0.2673 0.0223 pure error 0 0 cor total 808.67 alaa kareem mohamme al-khwarizmi engineering journal, vol. 20, no. 1, p.p. 116(2024) 8 fig . 5. counter plots and 3d of removal percent (%) of cip as a function of ph and initial concentration of cip (ppm). 3.3.2 adsorption time and initial concentration of cip the influence of adsorption time on the cip ions adsorbed by tac was investigated and presented in figure 6. the p-value and f-value are indicators of these outcomes, as shown in table 2. figure 6 shows that the adsorption time is the most important factor in the absorption process. when the initial concentration of cip (co) was between 100 and 200 ppm, increasing the adsorption time led to a higher percentage of cip being removed. when the concentration of cip is greater than 200 ppm, the adsorption capacity gradually slows down over time. this observation is due to the fact that the increasing concentration requires more time to be adsorbed. this behavior is in agreement with [10]. the optimum values for mixing time and initial concentrations are 454 min and 200 ppm, respectively. fig. 6. counter plots and 3d of removal percent (%) of cip as a function of time (min) and initial concentration of cip (ppm). 3.3.3 mixing time and tac dosage the effects of contact time and tac dosage on the removal efficiency of cip using tac were studied in the ranges 15 600 min and 0.025 0.25 g / 25ml, respectively. the results are shown in figure 7. this indicates that the removal efficiency is increased by increasing the contact time and tac dosage until the values of the removal efficiency become constant. the optimum values for mixing time and tac dosage are 454 min and 0.194 g / 25ml, respectively. these results are in agreement with the findings of [34]. alaa kareem mohamme al-khwarizmi engineering journal, vol. 20, no. 1, p.p. 116(2024) 9 fig. 7. counter plots and 3d of removal percent (%) of cip as a function of time (min) and tac dosage (g/25ml). 3.4 optimization of process variable the model accuracy was validated by optimizing the process parameters of the adsorption of cip on tac. the experimental result obtained confirmed the validity of the model, as shown in table 3, with 94% removal. table 3, adsorption of cip on tac optimization following the designed model. 4. adsorption isotherms adsorption isotherms, which are essential for creating adsorption systems, are calculated using equilibrium data. figure 8 illustrates how two linearized isotherm models (langmuir and freundlich) are used to match the sorption data for cip. consequently, the slope and intercept of the linear plot were employed to determine the empirical coefficients presented in table 4 for each model. eq. (4) represents the langmuir isotherm [35]. 𝑞𝑒 = 𝐾𝐿 𝑞𝑚 𝐶𝑒 1 + 𝐾𝐿𝐶𝑒 … (4) the linearized form of eq. (4) is given by eq. (5) 1 𝑞𝑒 = 1 𝑞𝑚 + 1 𝑞𝑚𝐾𝐿 1 𝐶𝑒 … (5) where 𝑞𝑒 adsorption capacity at equilibrium (mg/g). 𝑞𝑚 : maximum adsorption capacity (mg/g). 𝐾𝐿 : constant (l/mg). 𝐶𝑒 : the equilibrium concentration of the (mg/l). equation (5) can be used to determine both 𝐾𝐿 and 𝑞𝑚. the freundlich model is based on the assumption of multi-layer adsorption and heterogeneous surface energies. equation (6) represents the freundlich isotherm [23]. 𝑞𝑒 = 𝐾𝐹𝐶𝑒 1 𝑛 … (6) eq. (7) represents the linearization form of the freundlich model ln(𝑞𝑒) = ln(𝐾𝐹) + 1 𝑛 ln(𝐶𝑒) … (7) the parameters 𝑛 and 𝐾𝐹 are freundlich constants, which represent the adsorption intensity and the adsorption capacity, respectively. equation (7) is used to determine the values of 𝑛 and 𝐾𝐹. figure (8) shows the fitting of both models langmuir and freundlich. process parameters (coded) time ph dosage co predicted r2 actual r2 error % optimal values 454 8.75 0.194 200 0.9993 0.9981 0.0012 alaa kareem mohamme al-khwarizmi engineering journal, vol. 20, no. 1, p.p. 116(2024) 10 fig. 8. linear form of the freundlich and langmuir isotherm models for the sorption of cip onto tac. table 4 shows the parameters of both models langmuir and freundlich as well as the correlation coefficient (𝑅2). table 4, parameters of langmuir and freundlich equations according to the correlation coefficient values (𝑅2), the langmuir model matches the experimental results more closely than the freundlich model, which predicts a high monomolecular layer on the surface of the tac. 5. kinetics adsorption two kinetic models were used to analyze the adsorption kinetics of cip onto tac to comprehend the regulating mechanism and the adsorption rate: pseudo-first-order and pseudosecond-order as represented by equations (8) and (9), respectively. [36], [37]. ( 𝑑𝑞𝑡 𝑑𝑡 ) = 𝐾1 (𝑞𝑒 − 𝑞𝑡) … (8) 𝑑𝑞𝑡 𝑑𝑡 = 𝐾2(𝑞𝑒 − 𝑞𝑡)2 … (9) the parameters 𝑞𝑡 and 𝑞𝑒 (mg/g) represent the amounts of the tc adsorbed on the tac at time t and equilibrium, respectively. 𝐾1(min-1) and 𝐾2(𝑔/ 𝑚𝑔. 𝑚𝑖𝑛) represent the rate constants of the pseudo-first-order and pseudo-second-order kinetics, respectively. eqs. (10) and (11), respectively, give the linearized forms of the pseudo-first-order and pseudo-secondorder [38]. 𝑙𝑛(𝑞𝑒 − 𝑞𝑡) = ln 𝑞𝑒 − 𝐾1𝑡 … (10) 𝑡 𝑞𝑡 = ( 1 𝐾2𝑞𝑒 2) + ( 𝑡 𝑞𝑒 ) … (11) the experimental adsorption data are graphically presented in figure 9 using the pseudo-first-order and pseudo-second-order kinetics models. freundlich langmuir 𝐾𝐹 n 𝑅2 𝐾𝐿 𝑞𝑚 𝑅2 (l/mg) (mg/g) 37.13 2.76 0.859 24.95 256.41 0.9568 alaa kareem mohamme al-khwarizmi engineering journal, vol. 20, no. 1, p.p. 116(2024) 11 fig. 9. kinetics models for adsorption of cip onto tac. (a) pseudo-first-order, (b) pseudo -second-order reaction model. table 5, kinetics parameters of pseudo-first-order and pseudo-second-order adsorption models table 5 shows that the pseudo-second-order kinetic well fits the experimental data of cip adsorption on the tac. 6. study of thermodynamics three thermodynamic parameters, including, entropy change ∆𝑆0 , gibbs free energy change ∆𝐺0, and enthalpy change ∆𝐻0, were studied to investigate the thermodynamic behavior of the adsorption onto the tac. the gibbs free energy change ∆𝐺0, was determined by eq. (12) [39]. ∆𝐺𝑜 = 𝑅𝑇𝑙𝑛(𝐾𝑐) … (12) where r is the universal gas constant (𝑅 = 8.314 𝑘𝐽 𝑘𝑚𝑜𝑙. 𝐾⁄ ) and 𝐾𝑐 is the distribution coefficient that can be calculated by eq. (13) [40]. 𝐾𝑐 = 𝑞𝑒 𝐶𝑒 … (13) the relation between the thermodynamic parameters enthalpy change ∆𝐻𝑜, entropy change ∆𝑆𝑜, and gibbs free energy change ∆𝐺𝑜is given by eq. (14) [41]. ∆𝐺𝑜 = ∆𝐻𝑜 − 𝑇∆𝑆𝑜 … (14) substituting eq. (14) in eq. (12) gives ln 𝐾𝑐 = ∆𝑆° 𝑅 − ∆𝐻° 𝑅𝑇 … (15) the values of ln(kc) were calculated by eq. (13) at different temperatures. plotting ln (𝐾𝑐) vs. 1 𝑇 gives a linear relation from which the values of ∆𝐻𝑜 and ∆𝑆𝑜 can be calculated. figure 9 illustrates a positive correlation between the value of 𝐾𝑐 and temperature, indicating that when the temperature rises, 𝐾𝑐 also increases. table 6 presents a comprehensive overview of the thermodynamic parameters ∆go, ∆ho, and ∆so at various temperatures for the adsorption of cip onto tac. pseudo-first-order pseudo-second-order 𝐾1 𝑞𝑒 𝑅2 𝐾2 𝑞𝑒 𝑅2 (min-1) (mg/g) (g/mg. min) (mg/g) 0.0003 74.96 0.8999 0.001 51.282 0.9989 alaa kareem mohamme al-khwarizmi engineering journal, vol. 20, no. 1, p.p. 116(2024) 12 fig. 9. 𝐥𝐧 𝑲𝒄 versus 𝟏 𝑻 for the adsorption of cip on tac. table 6, thermodynamic parameters for the adsorption of cip by the active carbon the presence of negative values for ∆𝐺𝑜 signifies the natural spontaneity of the sorption process. the positive value of ∆ho suggests the endothermic nature of the adsorption process. the entropy change has a positive sign, which reveals that the randomness at the interface of solid and liquid will increase during the adsorption of cip [42]. 7. conclusion in the present study, the conversion of tea residue into activated carbon was accomplished, followed by its utilization for the efficient adsorption of ciprofloxacin from an aqueous solution. the optimal conditions for the adsorption process, resulting in a maximum removal efficiency of 94.4% for ciprofloxacin, are as follows: a mixing time of 454 minutes, an acidity ph of 8.75, a dosage of 0.194 g/25 ml of aqueous solution, and an initial ciprofloxacin concentration of 200 ppm. the bet analysis of the prepared activated carbon shows a surface area value of 774 m2/g and 0.563 cm3/g, respectively. the adsorption of ciprofloxacin on the active carbon that was synthesized may be effectively described using the langmuir model, which precisely predicts the equilibrium adsorption behavior. the langmuir model indicates a maximum adsorption capacity of 256.41 mg/g. the adsorption kinetics and reaction rate constant k2 in the pseudo-second-order model are characterized by a value of 0.001 g/ (mg. min). the thermodynamic analysis reveals that the adsorption of ciprofloxacin on tea-activated carbon is both endothermic and spontaneous. acknowledgment we appreciate the help of the lab staff from the al-khwarizmi college of engineering's biochemical engineering department in carrying out various research-related laboratory tests. we would also like to express our gratitude to the ministry of health for providing us with ciprofloxacin. references [1] s. d. salman, “adsorption of eavy metals from aqueous solution onto sawdust activated arbon,” al-khwarizmi engineering journal, vol. 15, no. 3, pp. 60–69, 2019. 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(2024) 1-16، صفحة 1، العدد20المجلد جلة الخوارزمي الهندسيةم عالء كريم محمد 16 بقايا الشاي وامتصاص سيبروفلوكساسين تعديل وتوصيف الكربون المنشط المحضر من ***ناديا حسين السباني **إسراء مزاحم رشيد *عالء كريم محمد ****وان نور رسالم وان عيسى حيائية/ كلية الهندسة الخوارزمي/ جامعة بغدادة االقسم الهندسة الكيميائي**،* الكيميائية/ كلية هندسة النفط والغاز/ جامعة الزاوية/ ليبيا*** قسم الهندسة **** قسم الهندسة الكيميائية وهندسة العمليات/ كلية الهندسة والبيئة / جامعة كيبانجسان/ ماليزيا dr.alaa@kecbu.uobaghdad.edu.iq*البريد االلكتروني: kecbu.uobaghdad.edu.iq2018israa_msc@*البريد االلكتروني:* n.alsbani@zu.edu.ly ***البريد االلكتروني: wannorroslam@ukm.edu.my****البريد االلكتروني: الخالصة االمتزاز من بقايا الشاي. تم دراسة الخواص الفيزيائية والكيميائية وكفاءة (ac) في تحضير الكربون المنشط عملةالمست للطريقةتقدم هذه الدراسة وصفا الكربنة عند الثانية و )4po3h( مض الفوسفوريكاح عمالالتنشيط باستاالولى مرحلتين: على )ac( إنتاج الكربون المنشط تموقد للكربون المنشط المحضر. تشغيلية عدة عوامل ت دراسةتمفقد . (cip)السيبروفلوكساسينالعقار الدوائي الكربون المنشط لغرض امتصاص عملاستدرجة مئوية. 450درجة حرارة االمتزاز، زمنالممتز، ومستوى الرقم الهيدروجيني، و cipالتركيز األولي لـ هذه العوامل تشمل كفاءة االمتزاز. فيمعرفة تأثيرها الغرفة لدرجة حرارة ب ، (sem)اإللكتروني الماسح ، والمجهر (ftir)التحليل الطيفي لألشعة تحت الحمراء عمالاختبار خصائص الكربون المنشط باستوتم وكمية المادة المازة. هو langmuirان نموذج وتمت دراسة نمط االمتزاز وتبين . (bet) المساحة السطحية والحجم المسامي بطريقة وحساب، (xrd)وحيود األشعة السينية على امتصاص السيبروفلوكساسين، يتمتع الكربون المنشط المنتج بالقدرةإذ (tac). على الكربون المنشط بالشاي cipعملية امتزاز لالموديل المناسب .الدرجة الثانية تمت دراسة حركية االمتزاز وتبين انه يمكن تمثيلها بتفاعل من وقد رام. م/غغمل 256.41قدرة امتصاص قصوى تبلغ ب mailto:dr.alaa@kecbu.uobaghdad.edu.iq mailto:israa_msc2018@kecbu.uobaghdad.edu.iq mailto:n.alsbani@zu.edu.ly mailto:n.alsbani@zu.edu.ly mailto:wannorroslam@ukm.edu.my this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 19, no. 2, june, (2023) p. p. 3951 extraction of bovine serum albumin by aqueous two-phase system using peg4000/sodium citrate and peg8000/sodium phosphate hawraa a. mahdi* khalid w. hameed** abdul-jabbar a. ali*** *,**department of biochemical engineering/ al-khwarizmi college of engineering/ university of baghdad/ baghdad/ iraq ***environment and water directorate/ ministry of science and technology/ baghdad/ iraq *email: hawraaamawi@gmail.com **email: kwhameed@kecbu.uobaghdad.edu.iq ***email: drabduljabbar63@yahoo.com (received 23 january 2023; accepted 10 april 2023) 001.4https://doi.org/10.22153/kej.2023.0 abstract aqueous two phase system (atps) or liquid-liquid extraction is used in biotechnology to recover valuable compounds from raw sources. in aqueous two-phase systems, many factors influence the partition coefficient, k, (which is the ratio of protein concentration in the top phase to that in the bottom phase) and the recovery percentage (rec%). in this research, two systems of atps were used: first, polyethylene glycol (peg) 4000/sodium citrate (sc), and the second, peg8000/ sodium phosphate (sph), for the extraction of bovine serum albumin (bsa). the behavior of rec% and k of pure (bsa) in atps has been investigated throughout the study by the effects of five parameters: temperature, concentration of polyethylene glycol (peg4000 and peg8000), the concentration of sodium citrate or sodium phosphate, ph, and the addition of sodium chloride as a supporting agent. the recovery percentage of bsa and its partition coefficient are significantly influenced by these factors to various degrees. the most influential variable in this study is peg concentration for both systems. in addition to the peg concentration, the stabilizing impact of nacl is a crucial factor. the interaction between biomolecules and peg gets more hydrophobic as the peg concentration is raised. in the first system (peg4000/sc), the maximum recovery percentage and partition coefficient were 98.99% and 97.69, respectively, at 31°c, peg4000 concentration 1.5g/10 ml, sodium citrate concentration 2.7 g/10 ml, ph 10, and 0.5 m nacl concentration. while in the second system (peg8000/sph), the maximum recovery percentage and partition coefficient was 98.93% and 92.12, respectively, at 31oc, peg8000 concentration 1.5 g/10 ml, sodium phosphate concentration 2.4 g/10 ml, ph 10, and concentration of nacl 0.5 m. keywords: aqueous two-phase system (atps), protein partitioning, partition coefficient, recovery percentage, bovine serum albumin (bsa). 1. introduction the aqueous two phase system (atps) was invented accidentally in 1896 by martinus willem beijerinck, but was not really used until the 1970s by per-åke albertsson [1], [2]. atps systems were developed and have been studied a lot in recent years. it is made up of different types of chemicals including, polymer-polymer and polymer-salt systems that can be mixed together, and it is used for a variety of purposes [3]. this process is better than other extraction techniques because it is environmentally friendly, affordable, and can be used to extract many different types of molecules [2]–[5]. water helps to separate and stabilize the structure of biomolecules in the two phases of aqueous two phase system [3], [5]–[7], while other liquidliquid extraction (lle) methods can damage mailto:*hawraaamawi@gmail.com mailto:**kwhameed@kecbu.uobaghdad.edu.iq mailto:***drabduljabbar63@yahoo.com https://doi.org/10.22153/kej.2023.04.001 hawraa a. mahdi al-khwarizmi engineering journal, vol. 19, no. 2, p.p. 3951 (2023) 40 biological products, since the process conditions and organic solvents are often harsh [4], [5]. biphasic systems are made of two different materials. they can be either made of two polymers, like peg and dextran, or a polymer and salt, like peg and phosphate, sulfate, or citrate. however, there are biphasic systems made of ionic liquids and short-chain alcohols [2], [4]–[6], [8]–[10]. some researchers have studied different types of atps to characterize and understand their ability to separate, extract, and purify biomolecules and particles [11]. despite the many benefits of using salt atps, there is a lack of understanding of how biomolecules partition in these systems, which makes it difficult to predict how they will behave. the concentration of a particular chemical (e.g. phosphate) and the surface characteristics of the target biomolecules (e.g. proteins) are both important factors when it comes to how the biomolecules behave in a system. in addition, the interactions between the biomolecules and system variables (e.g. ph, temperature, etc.) are also important [2], [12], [13]. the target protein in this study is bovine serum albumin (bsa), a water-soluble protein found in milk [14], [15], a by-product of the cow industry. it is an ideal bioproduct that can be utilized in many bioprocesses since it has no influence on most biochemical reactions and is inexpensive because it can be easily purified in huge amounts from bovine blood [16]. it is created in the liver, and secretory cells allow it to enter milk [17]. about 0.7-1.3% of the total milk protein is bsa, which has a molecular weight of 66 kda and an isoelectric point (pi) of 4.7–5.2 [14], [15], [17]–[20]. the partitioning of bovine serum albumin between two aqueous phases is a complex process that can be difficult to understand. it is important to know that the partitioning of biomaterial into separate phases is due to the interactions between it and the surrounding molecules, these interactions create a variety of forces that help to create the desired structure [21]–[25]. in order to study the effects of partitioning biomolecules in a liquid mixture, scientists have to conduct many experiments. this can often be expensive, so it is important to make the best choices when doing these experiments. this is because the process of partitioning a substance between different substances is complicated and unpredictable, based on the system variables and the characteristics of the biomolecules involved [26], [27]. in the current study, two of atpss were used to examine the partitioning of bovine serum albumin (bsa), named peg4000/sodium citrate (sc) and peg8000/sodium phosphate (sph). in this scenario, partitioning behavior of a model protein was studied, and the effect of system factors was analyzed, such as peg 4000 and peg 8000 concentrations (1.5-2.4 g/10 ml) each, and phase-forming salts, sodium citrate (sc) concentrations (1.8-2.7 g/10 ml), sodium phosphate (sph) concentrations (1.5-2.4 g/10 ml). other parameters were, temperature (10-31 oc) and (17-38 oc) for peg/sc and peg/sph, respectively, ph (7-10), and nacl (0.1-0.5 m) for both systems. protein content for peg/ salt atpss was (0.01 g/10 ml). the potential interactions of model proteins with other substances may be predicted using their varied physical properties. moreover, classical factorial design (cfd) was used to inquire deeply into the partitioning behavior of a model protein. this was done as a design experiment to improve our understanding of the proteins' behavior. the goal of this study is to determine which parameters (temperature, peg4000 concentration, peg8000 concentration, phosphate/citrate concentrations, ph, and the addition of nacl) have the greatest impact on the partitioning of bsa, and to use that knowledge to. 2. materials and methods 2.1 materials polyethylene glycol (peg) was purchased from himedia laboratories pvt. ltd., india, the molecular weight of the item was 4000 and 8000 g/mol, disodium phosphate, na2hpo4, (sph), and tri-sodium citrate, na3c6h5o7, (sc) was acquired from central drug house ltd., india, and sodium chloride (nacl) was provided by alpha chemika, india. the coomassie brilliant blue g-250 dye and bovine serum albumin (bsa) were bought from himedia laboratories pvt. ltd., india. a high quality of reagents was used in the analysis. the water utilized in this investigation was double distilled and deionized. 2.2 methods 2.2.1 preparation of aqueous two-phase system it is need to weigh the amount of different system components, sodium citrate (sc) (1.8-2.7 g/10 ml), and sodium phosphate (sph) (1.5-2.4 hawraa a. mahdi al-khwarizmi engineering journal, vol. 19, no. 2, p.p. 3951 (2023) 41 g/10 ml), to make it work. also weighing of peg4000 and peg8000 of (1.5 – 2.4 g/10 ml) each, to prepare solutions with the desired concentrations appropriate amount of bsa is dissolved in the solution of sodium citrate (sc) or sodium phosphate (sph), to obtain of simulated solution with concentration of 0.01 g/10 ml of bsa. atpss of peg/sc and peg/sph were created based on requirement of binodal curves [28]–[30]. appropriate ph 9 value was used to create the citrate and phosphate stock solutions. the two of atpss of peg/sc and peg/sph that were investigated to extract the bsa were made in screw tubes. all of two system parts were vortexed and completely blended with a magnetic stirrer for 10 minutes. the samples were spun around in a centrifuge device at 6000 rpm for 20 min so that the different parts of the samples could be separated. to make sure the systems were in equilibrium, they were left to sit at the desired temperature for around 24 hours, see figure 2.2. a syringe was used to properly separate the phases once phase equilibrium has been reached. below, is a simplified schematic of how one or two polymers may be mixed together to create an atps, see figure 2.1 [31]. the bottom phases' volumes were finally calculated, and samples were collected for protein concentration analysis [32]–[35]. fig. 2.1. a schematic of an atps. fig. 2.2. the formation of the two phases in an atps after mixing and settling. 2.2.2 bsa concentration determination to measure the concentration of the protein in a sample, a bradford technique using coomassie blue g250 was used [36] as shown in figure 2.3. to determine the protein concentration, the samples are taken from the bottom phase and diluted with a known volume of distilled water. their ultraviolet absorbance was then analyzed using a single-beam spectrophotometer (emc-11uv) from emclab or biophotometer 6131 from eppendorf [28, 29, 30] as shown in figure 2.4. similar solutions that are free from protein were used as blanks to make the necessary adjustments to prevent interference from peg and citrate or phosphate. at 595 nm, the optical density was performed at a minimum of three duplicates of each experiment or measurement. the degree of protein separation in the polymer phase is determined by the partition coefficient (k). to ensure the system is working as intended, we also calculated the percentage of recovery using the partition coefficient [31, 32, 33]. hawraa a. mahdi al-khwarizmi engineering journal, vol. 19, no. 2, p.p. 3951 (2023) 42 fig. 2.3. addition of bradford reagent (coomassie blue g250) to the collected samples fig. 2.4. analyzing ultraviolet absorbance of bsa using a biophotometer. the partition coefficient (k) is a measure of how much protein is left over after being extracted from a liquid. the higher the partition coefficient, the lower protein is left over in the bottom phase, i.e. k = 𝐶𝑇 𝐶𝐵⁄ … (1) where, ct is the protein concentration in the top layer. cb is the protein concentration in the bottom layer [20, 34, 35]. the recovery percentage (rec%) measures the degree of how well the extraction process is. the following equation was used to calculate the recovery percentage (rec%): rec% = %1001          in b c c … (2) where, cin is the initial concentration of protein in the bottom phase [26]. 3. results and discussion 3.1 temperature effect the effect of temperature on the recovery percentage of bsa and its partition coefficient has been studied when a proper concentration of peg4000 (1.5 g/10ml), sc (1.8 g/10ml) for peg4000/sc system, and (1.5 g/10ml) for both peg8000 and sph for peg8000/sph system were used. both systems were at ph 9 without the addition of nacl. due to the interconnected nature of an aqueous composition's components, such as electrostatic and hydrophobic forces, how temperature impacts how it behaves is extremely complex [32]. when the temperature is elevated, proteins can experience changes in their shape, structure, and stability, so the range of temperature is taken from (10-31 oc) for the first system (peg4000/ sc), and from (17-38 oc) for the second system (peg8000/ sph). figures 3.1 hawraa a. mahdi al-khwarizmi engineering journal, vol. 19, no. 2, p.p. 3951 (2023) 43 and 3.2 show the effect of temperature for systems peg4000/ sc and peg4000/ sph respectively. it can be seen from figures 3.1 and 3.2 that the recovery per cent (rec%) and partition coefficient (k) for protein increases as the temperature rises. this means that the percentage of protein that is recovered after being heated is greater at higher temperatures. in the second system, it was noticed that the rec% and k start decreasing with increasing temperature from (3138 oc). when the temperature changes, the liquids in an atps will also change. this can make it difficult to mix the two liquids properly, which can lead to problems. changes in temperature cause the molecules in a substance to move around more, which can affect how easily the substance can be divided into smaller pieces. this is because molecules move more easily through substances that are less viscous, denser, and tension-free [43], [44]. this result agreed with raja and murty, 2013, who cleared that the increase in temperature affect the phase composition of the atps beside the structure of proteins [26]. pirdashti et al, 2021, had a different opinion when he found out that the rise in temperature decreases the amount of protein that is recovered in the top phase [29]. because of temperature rise, the polymer becomes more hydrophobic; as a result, the contacts between the molecules of the polymer and water tend to weaken, and the amount of water in both phases decreases over time. since scientists know that the temperature in an atps experiment can affect the results, they always recommend keeping the temperature consistent. fig. 3.1. effect of temp on the rec% and k at conc. of 1.5 g/10 ml for peg 4000 and 1.8 g/10 ml for sc, ph 9, and without the addition of nacl. fig. 3.2. effect of temp on the rec% and k at conc. of peg8000 and sph of 1.5 g/10 ml each, ph 9, and without the addition of nacl. 3.2 concentration effect of peg4000 and peg8000 protein and peg interact differently; sometimes the interaction between the two is more hydrophobic, which means that the proteins stay apart more easily. raising the peg concentration in the system makes it harder for the protein to recover and makes the partition coefficient (k) much lower [45]. in both systems the concentration of peg4000 and peg8000 had a significant impact on how quickly and evenly bsa is partitioning, which affects how much of the protein can be recovered. the effect of concentration of peg for system peg4000/ sc and system peg8000/ sph are shown in figures 3.3 and 3.4 respectively. for 1.8 g/10 ml of sc and a peg4000/sc system, higher rec% and k of bsa were found to be 96.98% and 32.16, respectively, when peg4000 concentration is 1.5 g/10 ml. while for the second system, peg8000/sph, higher rec% and k of bsa were found to be 96.06% and 24.40, respectively, when peg8000 concentration of 1.5 g/10 ml and sph concentration is 1.5 g/10 ml. the two systems were set to the same temperature of 31 oc, ph 9 and without the addition of nacl. it can be seen from figures 3.3 and 3.4 that as the concentration of polyethylene glycol (peg) increases in the range of (1.5 – 2.4 g/10 ml), the percentage of protein recovered decreases. this result is agreed with shad et al, 2018, who illustrated in their research that when peg concentration is raised, proteins move from the upper to the lower phase 15 17 19 21 23 25 27 29 31 94.0 94.5 95.0 95.5 96.0 96.5 97.0 9 12 15 18 21 24 27 30 p ar ti ti o n c o e ff , k r ec o ve ry % temp oc recovery % partition coeff, k 15 17 19 21 23 25 94.0 94.5 95.0 95.5 96.0 96.5 16 19 22 25 28 31 34 37 40 p ar ti ti o n c o ef f, k r ec o ve ry % temp oc recovery % partition coeff, k hawraa a. mahdi al-khwarizmi engineering journal, vol. 19, no. 2, p.p. 3951 (2023) 44 in atps, this is probably because the protein has a stronger preference for water molecules, and the peg molecule is larger and less hydrophobic than water; which leads to rising the partition coefficient automatically [46]. however, ramji et al, 2011, went with similar finding, as the concentration of polymer in the top layer increases, the partition coefficient decreases since no more space is available for the protein to be partitioned among the different layers [47]. in contrast to what is shown in this work, faravash et al, 2007, [48] and antelo et al, 2015, [49] had a conflicted opinion when they concluded that increasing of peg concentration levels had a beneficial effect on rec% and k which are increased according to peg increment. fig. 3.3. effect of peg4000 on the rec% and k at t= 31oc, conc. of sc 1.8 g/ 10 ml, ph 9, and without the addition of nacl. fig. 3.4. effect of peg 8000 on the rec% and k at t = 31oc, conc of sph 1.5 g/10 ml, ph 9, and without the addition of nacl 3.3 concentration effect of sodium citrate and sodium phosphate by doing experiments, it was found that the amount of sodium citrate (sc) or sodium phosphate (sph) salt in a solution has an effect on how much protein is extracted in atps and how well it is partitioned. according to baskaran et al, 2018, [30], [50], where they found in peg/salt system that the rec% and k increases when salt concentration increased. by checking figures 3.5 and 3.6, it is clear to see that the rec% and k are increased when salt is added, this makes the solution more concentrated. this is called the salting-out effect, when something is salted, the salt molecules move up from the bottom to the top and this happens with proteins, too and helps to improve the extraction process and thus the rec% and k rises. it was found by increasing sc concentration from 1.8 g/10 ml to 2.7 g/10 ml for peg4000/sc system, the rec% increased from 96.69% to 97.97%, and the k increased from 29.24 to 48.20, as shown in figure 3.5. fig. 3.5: effect of sc on the rec% and k at t=31oc, conc. of peg4000 = 1.5 g/10 ml, ph 9, and without the addition of nacl. 6 9 12 15 18 21 24 27 30 33 86 88 90 92 94 96 98 1.4 1.6 1.8 2 2.2 2.4 p ar ti ti o n c o ef f, k r ec ve ry % conc. of peg4000, g/10 ml recovery % partition coeff, k 17 18 19 20 21 22 23 24 25 94.4 94.6 94.8 95.0 95.2 95.4 95.6 95.8 96.0 96.2 1.4 1.6 1.8 2 2.2 2.4 p ar ti ti o n c o ef f, k r ec o ve ry % conc. of peg8000, g/10 ml recovery % partition coeff, k 28 32 36 40 44 48 96.6 96.8 97.0 97.2 97.4 97.6 97.8 98.0 1.7 1.9 2.1 2.3 2.5 2.7 p ar ti ti o n c o ef f, k r ec o ve ry % conc. of sodium citrate, g/10 ml recovery % partition coeff, k hawraa a. mahdi al-khwarizmi engineering journal, vol. 19, no. 2, p.p. 3951 (2023) 45 fig. 3.6. effect of sph on the rec% and k at t = 31oc, conc. of peg8000 = 1.5 g/10 ml, ph 9, and without the addition of nacl in peg8000/sph system, it is shown that the rec% increased from 95.94% to 97.86%, and the k increased from 23.64 to 45.69, by increasing sph concentration from 1.5 g/10 ml to 2.4 g/10 ml as in figure 3.6. this result was convenient to raja and murty, 2013, baskaran et al, 2018, faravash et al, 2007, antelo et al, 2015, and kee et al, 2021, [26], [30], [48], [49], [51], and there is no incompatible opinion were found. 3.4 ph effect biomolecules can be partitioned between two phases according to their different charges and surface properties. this can change depending on the ph of the aqueous solution. protein molecules with a positive net charge will try to pull electrons away from other proteins, creating an electric force. however, if the ph is higher than the pi (which stands for "ph-indicator" or "potential isoelectric point"), the electric force is weakened and the proteins will end up with a net negative charge, and if it is lower, it becomes positive and there will be no net charge if ph and pi values are the same [44]. according to reports, when a system has a higher ph, the negatively charged biomolecules will partition more easily and the target biomolecule will tend to be found in the top phase. because of the positive dipole moment, proteins with a high ph value than their (potential isoelectric point) pi, are more attracted to pegrich phases [52], [53]. figures 3.7 and 3.8 show as the ph of the solution goes up, the partition coefficient (k) increases, which means that more protein will be recovered. for peg4000/sc system, it was found that at ph 10, the rec% and k values are the highest and were 97.86% and 45.69 respectively, as shown in figure 3.7. figure 3.8 shows ph changes can have effects on peg8000/sph system. the system shows increasing in rec% and k with increasing of ph and higher values of rec% and k were 98.10% and 51.66 respectively, at ph 10. pirdashti et al, 2021, saravanan et al, 2007, faravash et al, 2007, kee et al, 2021, and johansson 1985, [29], [39], [48], [51], [54] all had good agreement to our investigation, and there is no incompatible opinion were found. fig. 3.7. effect of ph on the rec% and k at t=31oc, peg4000 conc. of 1.5 g/10 ml, and sc of 2.7 g/10 ml, and without the addition of nacl fig. 3.8. effect of ph on the rec% and k at t=31oc, peg8000 conc. of 1.5 g/10 ml and sph of 2.4 g/10 ml, and without the addition of nacl. 22 26 30 34 38 42 46 50 95.5 96.0 96.5 97.0 97.5 98.0 1.4 1.6 1.8 2 2.2 2.4 p ar ti ti o n c eo ff , k r ec o ve ry % conc. of sodium phosphate, g/10 ml recovery % partition ceoff, k 18 22 26 30 34 38 42 46 94.5 95.0 95.5 96.0 96.5 97.0 97.5 98.0 6.5 7.5 8.5 9.5 10.5 p at it io n c o ef f, k r ec o ve ry % ph recovery % patition coeff, k 18 22 26 30 34 38 42 46 50 54 95.0 95.4 95.8 96.2 96.6 97.0 97.4 97.8 98.2 7 8 9 10 11 p ar ti ti o n c o ef f, k r ec o ve ry % ph recovery % partition coeff, k hawraa a. mahdi al-khwarizmi engineering journal, vol. 19, no. 2, p.p. 3951 (2023) 46 3.5 effect of the addition of nacl. as a final step in the present work, the effect of nacl addition has been studied as a way to improve the protein partitioning and the recovery rate of the protein. the partition coefficient in atpss is influenced by the addition of salts such as nacl, kcl [55]. these salts work as partitioning accelerators, ions in these salts have varying degrees of hydrophobicity, and the hydrophobic ions drive the partitioning of the opposite ions to phase with ions that have a higher hydrophobicity and vice versa [44], [45]. the biomolecule transitions from a phase that is saltrich to one that is polymer-rich due to the saltingout effect [42]. in figures 3.9 and 3.10, addition of nacl at concentration range (0.1-0.5 m) to peg4000/sc and peg8000/sph system show an increment in the rec% and k. in figure 3.9, higher values recorded for peg4000/sc system at (nacl 0.5 m) was 98.99% for rec%, and 97.69 for k. figure 3.10 showed that higher values of rec% and k were 98.93% and 92.12, respectively, for peg8000/sph system. raja and murty, 2013 settu et al, 2015, faravash et al, 2007, saravanan et al, 2007, ramesh and murty, 2015, gündüz, 2000 perumalsamy and murugesan, 2007, and regupathi et al, 2013, [26], [28], [30], [39], [41], [56]–[58] all went with similar findings and there is no any incompatible opinion. fig. 3.9. effect of nacl conc. on the rec% and k at t= 31oc, conc. of peg4000 conc. of 1.5 g/10 ml, and sc of 2.7 g/10 ml, ph 10. fig. 3.10. effect of nacl conc. on the recovery% and k at t = 31oc, conc. of peg8000 of 1.5 g/10 ml and sph of 2.4 g/10 ml, ph 10. 4. conclusions an aqueous two-phase system (atps) is an alternative to traditional methods of extraction, which involve using solvents to extract the proteins. it is a type of method that can be used to recover valuable soluble proteins from aqueous phases. in this study, two systems, peg4000/sodium citrate and peg8000/sodium phosphate were used for the extraction of bsa. the two systems have a high degree of efficiency. the atps is a simple process that can be used to separate bioproducts. this is a cheaper option than using traditional methods, and it is likely to be more effective in purifying products. the results showed that under certain conditions like concentration of peg, sodium phosphate/citrate, ph, temperature and nacl salt addition, it was possible to change the way bsa partitioned. when the quantities of the peg-solution and sc (or sph)-solution are equivalent, the bsa recovery percentage reaches 98% in a single stage for the first and second systems, implying that no more stages are necessary. acknowledgement the authors acknowledge university of baghdad, al-khwarizmi college of engineering, biochemical engineering department for the facilities and logistic support. the authors also appreciate the infrastructural facilities offered by al ameed university. 45 55 65 75 85 95 97.8 98 98.2 98.4 98.6 98.8 99 0 0.1 0.2 0.3 0.4 0.5 0.6 p ar ti ti o n c o ef f, k r ec co ve ry % conc. of nacl, g/10 ml recovery % partition coeff, k 50 55 60 65 70 75 80 85 90 98 98.1 98.2 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[58] i. regupathi, s. kalaivani, and n. sindhu, “bovine serum albumin partitioning in aqueous two-phase systems: effects of variables and optimization,” bioprocess. j., vol. 12, no. 1, pp. 29–41, 2013, doi: 10.12665/j121.regupathi. translation is too l (2023) 39-51، صفحة 2، العدد19مجلة الخوارزمي الهندسية المجلدحوراء عبد األمير مهدي 51 سترات / peg4000باستخدام األبقار بنظام ثنائي الطورالمائيمصل لبومين استخالص ا فوسفات الصوديوم/ peg8000 الصوديوم و ***عبد الجبار عباس علي **خالد وليد حميد *حوراء عبد االمير مهدي العراق /بغداد /كلية الهندسة الخوارزمي /جامعة بغداد /قسم الهندسة الكيميائية االحيائية *،** العراق /بغداد /التكنولوجياوزارة العلوم و / والبيئةبحوث المياه ة دائر*** hawraaamawi@gmail.com :البريد االلكتروني* kwhameed@kecbu.uobaghdad.edu.iq :البريد االلكتروني** drabduljabbar63@yahoo.com :البريد االلكتروني*** الخالصة هي طريقةو ،يلطور المائاثنائي تسمى نظام الصمن المواد الخام باستخدام تقنية استخذات اهمية عالية جزيئات الصاستختتضمن التكنولوجيا الحيوية وائل لفصل لستلفين من اهذه الطريقة نوعين مخفي ستخدم يالخاليا أو المواد األخرى. االنزيمات وكالبروتينات و أنواع مختلفة من الجزيئات الصالستخ ؤثر العديد من ائية الطور تائية ثنوفصل مخاليط من الجزيئات الحيوية. في األنظمة الم الصسيلة فعالة للغاية الستخو ازيئات وقد وجد بالتجربة بأنهوتنقية الج البحث في هذا .rec اد %االسترد( ونسبة في الطور السفلي ذلك الموجود إلى ويالعل طورنسبة تركيز البروتين في ال وهو) k تجزئةالعوامل على معامل ال يتكون منوالثاني مسترات الصوديوو (peg4000) 4000ل بولي إيثيلين جاليكويتكون من األول: مصل االبقارلبومين الستخالص اتم استخدام نظامين النظام في لنقيامصل األبقار أللبومين k و rec بأن نسبة االسترداد % الحظةتم م. فوسفات الصوديومو(peg8000) 8000بولي إثيلين جاليكول ديوم أو ترات الصو، تركيز س (peg8000) و (peg4000)، تركيز : درجة الحرارةهي عوامل ةخمس تأثير دراسة من خالل ثنائي الطور المائي لكال pegو تركيز المتغير األكثر تأثيًرا في هذه الدراسة هوجد ان فة كلوريد الصوديوم كعامل مساعد.فوسفات الصوديوم ، درجة الحموضة ، وإضا peg.أكثر كراهةً للماء مع زيادة تركيز pegالنظامين حيث يصبح التفاعل بين البروتين و تركيز ومل ، 10/ جم 1.5 (peg4000) تركيزعند ، على التوالي 97.69٪ و 98.99في النظام األول، كانت نسبة االسترداد القصوى ومعامل التقسيم لتوالي عند اعلى 92.12٪ و 98.93الذي سجل نسبة استرداد قصوى ومعامل تقسيم مقارنة بالنظام الثاني ،سترات الصوديوم مل ل 10جم / 2.7 ، جة مئويةدر 31 حرارةالدرجة الظروف عند أفضل مل. حيث كانت 10جم / 2.4مل، و تركيز فوسفات الصوديوم 10جم / 1.5 (peg8000)تركيز .كال النظامينفي ، 0.5، وتركيز كلوريد الصوديوم 10 األس الهيدروجيني mailto:hawraaamawi@gmail.com*البريد mailto:hawraaamawi@gmail.com*البريد mailto:**kwhameed@kecbu.uobaghdad.edu.iq mailto:drabduljabbar63@yahoo.com***البريد mailto:drabduljabbar63@yahoo.com***البريد <4d6963726f736f667420576f7264202d20ddc7d8e3c920e6cf20e3c7e1df20e6cf20dae1ed312d203134> this is an open access article under the cc by license : al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 18, no. 3, september, (2022) p. p. 114 design and analysis of a spraying robot fatima m. jasim* malik m. ali** ali h. hamad*** *,**department of mechatronics engineering/ al-khwarizmi college of engineering/ university of baghdad/ baghdad/ iraq khwarizmi college of engineering/ -al***department of information and communication engineering/ baghdad/ iraq /university of baghdad *email: fatomaa.eng@gmail.com **email: malik@kecbu.uobaghdad.edu.iq ***email: ahamad@kecbu.uobaghdad.edu.iq )2022 july3 ; accepted 220228 march received ( https://doi.org/10.22153/kej.2022.07.001 abstract an indoor spraying robot is built in this research to solve numerous challenges associated with manual spraying. the mechanical, hardware and essential technologies used are all detailed and designed. the proposed spraying robot's conceptual design is split into two parts: hardware and software. the mechanical design, manufacturing, electrical, and electronics systems are described in the hardware part, while the control of the robot is described in the software section. this robot's kinematic and dynamic models were developed using three links that move in the x, y, and z directions. the robot was then designed using solidworks software to compute each connection's deflection and maximum stresses. the characteristics of the stepper motors, power screw and belt drive, are calculated. finally, an arduino-nano controller and stepper motor actuators were used to build and run the robot. as a result, the robot was able to move smoothly vertically and horizontally, according to the findings of the experiments as shown in figures 22, 23, 24, and 25. these figures showed the position and velocity curves of the links of the robot. keywords: cartesian robot, kinematic, dynamic, system design. 1. introduction during the development of science and technology, industrial robots appeared in industrial operations. industrial robots are electromechanical devices that can perform industrial tasks accurately; besides that, they are used to reduce the risks of industrial processes for humans in continuous work and reduce the consumption of materials. industrial robots can move in rotary motions such as articulated, scara, cylindrical, spherical or linear motion. the cartesian robot is also called a rectilinear or gantry robot. it has three linear joints (or a combination of them) that use the cartesian coordinate system (x, y, and z). this robot may also have an attached wrist to allow for rotational movement. the prismatic joints deliver linear motions along the respective axes. this robot is employed in material handling, computer numeric control machine load/unload, spraying materials, etc. the spraying operation is one of the essential processes in industrial robots, the most important of which is spraying for painting walls, cars, and devices and spraying insecticides on plants to get rid of agricultural pests and others. also, they are used in purgation hospitals to prevent viruses. therefore, the use of industrial robots to spray instead of humans is vital to caring for the health of the human body because it is affected by the paint and ventilation conditions of the spraying room. furthermore, these robots also achieve a good quality of the spray-painting of the products. in (2013), [1] review the works related to fatima m. jasim al-khwarizmi engineering journal, vol. 18, no. 3, p.p. 114 (2022) 2 coating thickness problems and improving the multi-objective constraint. however, it did develop methods for modeling the deposition of materials such as gaussian, cauchy, parabolic, and beta models, but it did not come with satisfactory results. fortunately, the min-max method has proven itself in formulating the paint film function for free-form surfaces. the appropriate tool path within an appropriate time and membrane quantity deviation was also inferred. from this data, the paint deposition rate model algorithm and the assumption of the gun shape of the paint like a cone were available. in 2015, [2] compare the cost and risks of hand painting over painting robots, a threeaxis (x, y, and z) with a two-part cartesian robot controlled by a plc and a computer was implemented. the first part is the unit of movement of the three axes x, y and z. each axis contains a single-phase motor and transmission mechanisms and sensors to control motion. the second is the coating unit created by a pneumatic system. in 2015 [3], the robot chassis was developed to suit painting and interior wall decoration works, and it consists of 8dof, of which 6dof are robotic arms mounted on a 2dof movable base which are connected to it by four points of wheels. the differential system was driven, and a kinematic model of the robot joints was shown, and through the resulting matrix from the jacobin matrix, the movement was planned and controlled. in 2017 [4] suggested a mathematical spray model of robot painting system based on gaussian distribution intensity of spray painting operation, it also compared a characters of color-intensity when changing the distance between airbrush and painting surface within the spraying time. in 2017, a gantry robot derived a mathematical and dynamic model using a bond graph technique. furthermore, the robot has simulated its motion on matlab within solidworks design and it was using a quadratic function with a velocity profile called a trajectory plan of the robot as in [5]. in 2019 [6], the dynamic model obtained the appropriate inertia parameters of the kuka lwr robot and its final efficacy. the geometric parameters also distinguished as shown in the tables the fastest time by defining those parameters as the joint torque was estimated with the rms difference. based on the robot's self-sensing, the force sensor was replaced by an estimate of the external forces applied, and the torque was related to the jacobin matrix. the kinetic accuracy clarified the accuracy of the external forces. in (2020) [7], a suitable material was proposed to design industrial robots, especially spray-painting robots. so, it had agreed to choose aluminum alloy to create the arm to reduce the weight of the portable arm and to choose steel alloy in the design of the base because it requires high rigidity and strength. in (2021) [8], a painting mobile robot was designed to avoid accidents of painting buildings on humans. the structure is designed from a moving part with a spray gun using two arduino uno boards connected wirelessly (to get rid of the burden of long electrical wires). first, the robot detects the area to be painted and completes it with high accuracy on its own. next, the robot moves through the dc motor to move the four wheels, where the position of the wall to be painted is detected using the ultrasonic sensor. then the spray gun paints the wall either horizontally or vertically. this paper presents the kinematic and dynamic model of the 3-dof cartesian robot (x, y, and z) for painting wall operation and analyzes robot fabrication for each link of it. in addition, the mechanical structure of this robot with its details is discussed. section 2 presents the derivation of the kinematic and dynamic model of the 3-dof cartesian robot. section 3 explains the mechanical structure and electronic circuit design. finally, section 4 discusses the numerical and graphic results of the proposed models and the experimental results of the movement. 2. mathematical models 2.1 kinematic model the robot manipulator is designed by a set of links that are connected within by joints which are revolute or prismatic, so n joints will haven + 1 links, because each joint connects two links. with the joint, there is a joint variable, denoted by qi. in the case of a revolute joint, qi is the angle of rotation, and in the case of a prismatic joint, qi is the joint displacement [9]. the kinematic model represents the motion of each link without respect to force; however, the forward kinematics model is an analysis that gives the relationship between the individual joints of the robot and the position and orientation of the endeffector. denavit-hartenberg's (dh) method finds a forward kinematic consisting of four variables for each link, such as a, d, ɵ, and α [14] and [15]. a is the link length, d is the link offset, ɵ is the joint angle, and α is the joint twist [10]. a manipulator whose first three joints are prismatic is a cartesian manipulator. it has cartesian coordinates representing the joint variables—the structure and workspace of the robot are shown in figures 1 and 2. fatima m. jasim al-khwarizmi engineering journal, vol. 18, no. 3, p.p. 114 (2022) 3 fig. 1. workspace of cartesian robot. fig. 2. three links cartesian robot. table 1, d-h parameters of robot. a d α θ 0 �� -90 -90 0 �� 90 -90 0 �� 0 0 from above table matrices of each link is obtained as follow: ���=�1 0 0 00 1 0 000 00 10 ��1 , ���=�1 0 0 00 1 0 000 00 10 ��1 , ���=�1 0 0 00 1 0 000 00 10 ��1 where t is the transformation matrix for the axes of frame �� ����� (last frame) with respect to the coordinate frame �� ����� (previous frame). the transformation matrix of the end-effector to the reference frame is concluded by multiplying the previous matrices, so ���= ��� × ��� × ��� …(1) ���= �1 0 0 ��0 1 0 ��00 00 10 ��1 � where ��, ��, ��� �� are the joint space of each link. joint velocity and acceleration of end-effector are determined with respect to the base frame, hence: ���= ����− ���� + ���� …(2) ��� = (���−g) � − ����+ ���� …(3) where g is the gravitational acceleration, �� is the joint velocity of links, and �� is the joint acceleration. 2.2 dynamic model from the dynamic model, the equation of motion is achieved. besides that, the system's response can be obtained by using the state-space model found from the dynamic model [11] and [16]. there are several techniques to find dynamic equations in robot manipulators, such as the newton-euler equations. ������ = �˗ !����� …(4) ����"� = �˗ !���"� ˗ #��"� …(5) ����$� = �˗ !���$� …(6) where ��, ��� , ���� , ����, !�, and � are the mass, joint position, joint velocity, joint acceleration, damper coefficient, and force applied respectively, and #� is the stiffness coefficient of second link that is caused by the belt. the subscript y1, x1, and z1 represent the first link, second link and the third link. to derive the dynamic model of robot manipulator, the masses are weight using a suitable scale. this robot has three masses moving vertically and two masses moving horizontally, subsequently [9]. %&�� ' �� ' ��( 0 00 &�� ' ��( 00 0 ��) *���� ' +��"���$� , +%!� 0 00 !� 00 0 !�) *������"��� $� ,+%0 0 00 -� 00 0 0) .����"��$� / = % � � �) … (7) fatima m. jasim al-khwarizmi engineering journal, vol. 18, no. 3, p.p. 114 (2022) 4 above are the equations of motion of each link; however, those equations can be simulated by using the state-space model as follows: ��0 = ���� ...(8) �"0=��"� …(9) �$0=��$� …(10) the state space formula given by: 2� = 3 2 ' 4 5 …(11) the output of the proposed system is the position of the end-effector for cartesian coordinates (x, y, and z of robot links) are obtained through the equation below: y= c x + d u ...(12) from equation 11 the state space model for cartesian robot is given by: ⎣⎢⎢ ⎢⎢⎢ ⎡�������0��"���"0��$���$0 ⎦⎥⎥ ⎥⎥⎥ ⎤ = ⎣⎢ ⎢⎢ ⎢⎡000000 1< =>�?�@?0@?ab0000 000< =c0?0@?ab00 001< =>0?0@?ab00 000000 00001<=>�?a b ⎦⎥ ⎥⎥ ⎥⎤ ⎩⎪⎨ ⎪⎧�����0�"��"0�$��$0 ⎭⎪⎬ ⎪⎫ + ⎣⎢⎢ ⎢⎢ ⎡000000 0& �?�@?0@?a(0000 000000 000& �?0@?a(00 000000 00000& �?a(⎦⎥⎥ ⎥⎥ ⎤ ⎩⎪⎨ ⎪⎧ 0 � − &�1 ' �2 ' �3(+0 �0 � ⎭⎪⎬ ⎪⎫ …(13) 3. design of the cartesian robot 3.1 the structure of cartesian robot the cartesian robot is designed with three links in the x-direction, y-direction, and z-direction. this robot is designed for wall operations, as shown in fig.3; the structure of the cartesian robot was designed with the help of solidworks software. the first link moves in the y-direction, ranging from 0 to 90 cm. two stepper motors create the motion; each one has a maximum power equal to 18 watts and transforms rotational motion to linear motion by using two lead screws, as shown in fig.4. the link choice for the structure is made from an aluminum beam that is 2040 v-slot type made from 6063-t5 aluminum material, because it achieves a rigid and lightweight frame, as shown in fig.5. the mechanical specifications are listed in table 2. fig. 3. structural design of robot in solidworks. fig. 4. front view of the first link. fatima m. jasim al-khwarizmi engineering journal, vol. 18, no. 3, p.p. 114 (2022) 5 fig. 5. aluminum profile 2040 for first link. table 2, mechanical properties of aluminum profile 2040 property value profile dimensions 20x40 mm slot width 6mm slot depth 6mm weight 0.5 kg/m available sizes do 3000 mm thickness 0.30mm-customized mass of inertia(ix) 4.64n�o mass of inertia(iy) 1.42n�o section modulus(zx) 2.32n�� section modulus(zy) 1.32n�� working tension 2.205n/mm product force 110mpa the vertical beams may be exposed to buckling, so the critical load of each beam is calculated as equal to 8005.99n. next, the maximum stress and deflection of each beam is calculated by using solidworks software, as shown in figs 6 and 7. the lead screw that transforms rotational motion to linear motion is made from stainless steel and connected with a brass copper nut. the capacity and basic life of lead screw are obtained by solidworks, as shown in figs 8 and 9. also, the standard parameters of the chosen lead screw are indicated in table 3. fig. 6. stress calculation of first link beams. fig. 7. deflection calculation of first link beams. fig. 8. stainless steel lead screw. fatima m. jasim al-khwarizmi engineering journal, vol. 18, no. 3, p.p. 114 (2022) 6 fig. 9. solidworks calculation of stainless screw. table 3, parameters of lead screw. parameters value pitch 2mm outer diameter 8mm coefficient of friction for screw &μ�( 0,08 coefficient of friction for nut &μ�( 0.06 nut diameter 20mm the second link of the robot moves a 48cm range horizontally in the x-direction. this motion is created by on stepper motor with a maximum power of 20.4 watts. the link was made from the same aluminum beam as the first link, and the belt drive is transformed from rotational motion to linear motion, as shown in fig.10. the horizontal beam that carries the x and z link in this system bears the overall load, so, the maximum stress and deflection are 1.6876 mm, and 12.6013 mpa, as shown in figs 11 and 12. the belt used in the xdirection to achieve the smoothest-movement is called 2gt timing belt (flat belt), as shown in fig.13 and table 4. fig. 10. front view of the second link of the robot. fig. 11. deflection calculation of second link beam. fatima m. jasim al-khwarizmi engineering journal, vol. 18, no. 3, p.p. 114 (2022) 7 fig. 12. stress calculation of second link beam. fig. 13. gt2 timing belt structure. table 4, the specifications of belt. specification value pitch 2mm width 6mm length 160cm height 1.38mm tooth height 0.75mm breaking strength 0.55158kn working tension 0.027801kn modulus of elasticity 0.05 gpa the final link of the robot moves in the zdirection with a 30cm range. this link is manufactured the same as the first link, i.e. the same beam and screw, as shown in fig.14. the assembly structure of the robot is shown in fig.15. fig. 14. side view for the final link of the robot. fig. 15 the structure of cartesian robot. 3.2 electrical and electronic design the robot should move in a smooth and accurate movement. to achieve that, a particular motor like a stepper motor was used to indicate precise and calculated steps without building a complex control system. this motor has a highpower density and is capable of high micro-step resolution and quiet operation with minimal resonance. the bipolar type of this motor is used to obtain direction and effort. to control a stepper fatima m. jasim al-khwarizmi engineering journal, vol. 18, no. 3, p.p. 114 (2022) 8 motor, an arduino-nano connects to the driver (drv8825) for the stepper motor, as shown in fig.16. the stepper motor specifications are shown in table 5, and the block diagram of the electrical circuit of the robot is shown in fig17. table 5, hybrid stepper motor features feature 17hs1538 17hs1600 (x&z-link) (y-link) maximum axial force 10n 10n maximum radial force 28n 28n holding torque 0.45 n.m 0.80 n.m step angle 1.8º 1.8º operating voltage 12volt 12volt rated current 1.7 ampere 1.5 ampere weight 320g 550g inductance 3.2 m.h/phase 7.0 m.h/phase insulation resistance 100 mω,/500vdc 100 mω,/500vdc dielectric strength 500 vac 500 vac rotor inertia 54 g.n�� 102 g.n�� shaft radial play 0.2 max 0.2 max shaft diameter 5mm 5mm shaft axial play 0.8 max 0.8 max fig. 16 stepper motor nema17 and its driver. fig. 17. block diagram of motion sequence. 4. experimental and simulation results 4.1 stepper motor results the characteristics of the stepper motor are calculated and shown in table 6. it can be observed that the motor's powers are different depending on the position and the load that carries it out. table 6, 17hs6001 and 17hs1538 motors calculations. term 17hs6001 17hs1538 (x&z-link) (y-link) maximum speed([�) 2.86 rev/sec 5.51 rev/sec step per revolution 200 step/rev 200 step/rev minimum time step 1.75 ms 0.907 ms maximum power 18 watt 20.4 watt angular velocity 17.96 rad/sec 34.6 rad/sec 4.2 lead screw and belt results the terms of power screw and belt drive are determined by standard equations in [12] and these values are shown in tables 7 and 8. fatima m. jasim al-khwarizmi engineering journal, vol. 18, no. 3, p.p. 114 (2022) 9 table 7, lead screw of first link and last link results. term y-link screw z-link screw load (\�( 27.28 n 7.85 n force applied( ]�( 4.365 n 1.26 n �^_�5`� 28.92 n.mm 8.34 n.mm power (a�( 519.4 watt 288.56 watt helix angle 4.516985 4.516985 average diameter(r) 7mm 7mm table 8, belt of second link results. term value load (\�( 15mm force applied( ]�( 4.365 n 1.26 n �^_�5`� 28.92 n.mm 8.34 n.mm power (a�( 519.4 watt 288.56 watt helix angle 4.516985 4.516985 average diameter(r) 7mm 7mm 4.3 simulation results 4.3.1 kinematic model response when entering the dh parameters of the robot in matlab, we can conclude the plot directions of the robot's links and the robot's path, as shown in fig. 18 and fig.19. figure 18 shows the robot's configuration in three dimensions and the endeffector's initial position, while figure 19 shows the path of the robot motion for two cycles. fig. 18. simulation of cartesian robot on matlab. fig. 19. path of two cycles. fatima m. jasim al-khwarizmi engineering journal, vol. 18, no. 3, p.p. 114 (2022) 10 4.3.2 dynamic model response to simulate the behavior of each joint space of the robot, input the parameters from table 9 of the state-space were modelled (eq. 13) in matlab simulink. table 9, parameters of dynamic model. parameter value &�� ' �� ' ��( 2.4 kg (�� ' ��( 1 kg �� 0.8 kg stiffness coefficient(-�( 0.53n/m damper coefficient of screws[13] 0.0064 n.s/m damper coefficient of belt 0.000001n.s/m � 4.365n � 0.1429n � 1.26n &�� ' �� ' ��(+ 23.544n fig. 20. first response of end-effector position. figure20 represents the system's response; the blue line is the end-effector’s position in the ydirection, the red line is the end-effector’s position in the x-direction, and the yellow line is the endeffector’s position in the z-direction. as shown, xposition oscillates because of the spring effect (stiffness) created by the reaction of the belt. figure21 represents the response of the system when value is neglected. therefore, we notice the position in the y-link increasing because the applied force is rising after the weight of the links is neglected. fig. 21. second response of end-effector position. fatima m. jasim al-khwarizmi engineering journal, vol. 18, no. 3, p.p. 114 (2022) 11 4.3.3 experimental result when running the robot, position and velocity with time have been calculated for link x-direction (second link) with a belt transformation element and z-direction (last link) with a screw transformation element. the motion starts from the initial position, as shown in fig. 22; the second link moves gradually in the x-direction for 1.2 seconds for the transient time of the robot system to get a steady state. after that, this link moves at a constant velocity, as shown in fig 23. fig. 22. x-position result for the second link. fig. 23. velocity for the second link. while in the z-direction, the motion starts from an initial position until 500 mm, as shown in fig. 24, the last link moves for 13.55 seconds. this time is low compared with the x-direction’s motion because the previous link moves the screw slowly at 3.3 mm/sec. fig. 25 shows that the velocity moves from zero until it reaches the maximum velocity, and it decreases to zero after getting to the final position. fig. 24. z-position result for the third link. fig. 25. velocity for the third link. fatima m. jasim al-khwarizmi engineering journal, vol. 18, no. 3, p.p. 114 (2022) 12 figure26 represents the difference between the response of a dynamic system model (measurement data) and the experimental results when running the robot; the blue line is the endeffector’s position in the z-direction when computing the system’s parameters and the red line is the actual result of end-effector’s position in the z-direction. fig. 26. comparison between dynamic model and experimental result of z-position. figure 27 also shows the same difference but for the end-effector’s position in the x-direction. as shown the blue line is linear, the robot actually moves smoothly in the x-direction as shown. fig. 27. comparison between dynamic model and experimental result of x-position. 5. conclusion compared to manual painting, the robotic spraying system has achieved optimal durability, safety, efficiency, and ease of use. all of the goals set for the proposed spraying robot have-been completed. the x-axis, y-axis, z-axis, and endeffector modules were all properly developed and built-in terms of mechanical design. all motors are mountings and couplings, and they are p o s it io n ( m m ) fatima m. jasim al-khwarizmi engineering journal, vol. 18, no. 3, p.p. 114 (2022) 13 correctly adjusted. all of the prismatic joints were successfully developed. the structure is designed with sturdy and flexible arms to move smoothly, and the stress values for each link have been adjusted to ensure that the weights are handled to prevent bending and abrasion. the power systems module and the arduino-nano controller were successfully created in electrical and electronic systems. the software effectively controlled each joint of the spraying robot that completed the appropriate path for painting the wall. according to the experiment results, the proposed robot could move quickly in both vertical and horizontal motions. in future work, a raspberry pi controller could be used instead of an arduino-nano controller. also, a machine vision and a camera are mounted on the robot to visualize and map for the path of the end-effector and to detect the windows and the door. 6. references [1] chen, wei, and dean zhao. “path planning for spray painting robot of workpiece surfaces.” mathematical problems in engineering, vol. 2013, 2013, pp. 1–6., https://doi.org/10.1155/2013/659457. [2] aris, ishak bin, and a. k. iqbal. “design and fabrication of a cartesian painter robot for the construction industry.” international journal of mechanical engineering education, vol. 34, no. 2, 2006, pp. 125–144. [3] sorour, mohamed. "robopainter–a conceptual towards robotized interior finishes." (2015). [4] scalera, lorenzo, et al. “airbrush robotic painting system: experimental validation of a colour spray model.” advances in service and industrial robotics, 2017, pp. 549–556., https://doi.org/10.1007/978-3-319-612768_57. [5] tuli, tadele belay. "mathematical modeling and dynamic simulation of gantry robot using bond graph." international conference on information and communication technology for develoment for africa. springer, cham, 2017. [6] katsumata, takuma, et al. “optimal exciting motion for fast robot identification. application to contact painting tasks with estimated external forces.” robotics and autonomous systems, vol. 113, 2019, pp. 149–159. [7] n. patel and r. sarvaiya, “study of material characteristics for efficient design of spray painting robot,”, international research journal of engineering and technology (irjet), vol.07, issue03, 2020. [8] muneer, amgad, and zhan dairabayev. “design and implementation of automatic painting mobile robot.” iaes international journal of robotics and automation (ijra), vol. 10, no. 1, 2021, p. 68. [9] spong, mark w., et al. robot modeling and control. new york: wiley, 2020. [10] siciliano, bruno, et al. force control. springer london, 2009. [11] ljung, lennart, and torkel glad. modeling of dynamic systems. prentice-hall, inc., 2002. [12] khurmi, r. s., and j. k. gupta. a textbook of machine design. eurasia publishing house, 2005. [13] ansoategui, igor, and francisco j. campa. “mechatronics of a ball screw drive using an n degrees of freedom dynamic model.” the international journal of advanced manufacturing technology, vol. 93, no. 1-4, 2017, pp. 1307–1318. [14] tahseen f. abaas, ali a. khleif, and mohanad q. abbood, " inverse kinematics analysis and simulation of a 5 dof robotic arm using matlab," al-khwarizmi engineering journal, vol. 16, p. p. 110 , march, (2020). [15] iman s. karem, talal a. jabbar a.wahab, and mawadah j. yahyh. “design and implementation for 3-dof scara robot based plc,” al-khwarizmi engineering journal, vol. 13, no. 1, p.p. 4050 (2017). [16] maryam sadeq ahmed, and et al. “robust computed torque control for uncertain robotic manipulatorss.” al-khwarizmi engineering journal, vol. 17, no. 3, 2021, pp. 22–28., https://doi.org/10.22153/kej.2021.09.002. ) 2022( 1-14، صفحة 3العدد، 18مجلة الخوارزمي الهندسية المجلد فاطمة محمد جاسم 14 تصميم وتحليل روبوت الرش مالك محمد علي** فاطمة محمد جاسم* علي حسين حمد*** جامعة بغداد كلية الهندسة الخوارزمي/ **قسم هندسة الميكاترونيكس/ ،* بغدادجامعة كلية الهندسة الخوارزمي/ والمعلومات/ قسم هندسة االتصاالت *** fatomaa.eng@gmail.com :البريد االلكتروني* malik@kecbu.uobaghdad.edu.iq :البريد االلكتروني** ahamad@kecbu.uobaghdad.edu.iq ***البريد االلكتروني: الخالصة المرتبطة بالرش اليدوي. تم تفصيل وتصميم التقنيات الميكانيكية واألجهزة المشاكلتم بناء روبوت رش داخلي في هذا البحث لحل العديد من كي والتقنيات األساسية المستخدمة. ينقسم التصميم التصوري لروبوت الرش المقترح إلى جزأين: األجهزة والبرامج. يتم وصف التصميم الميكاني بينما يتم وصف التحكم في الروبوت في قسم البرنامج. تم تطوير النماذج الحركية األجهزة،والتصنيع واألنظمة الكهربائية واإللكترونية في جزء solidworksتم تصميم الروبوت بعد ذلك باستخدام برنامج ) .x , y ,z ( والديناميكية لهذا الروبوت باستخدام ثالثة روابط تتحرك في اتجاهات والمحركات المتدرجة لبناء وتشغيل الروبوت. arduino-nanoتم استخدام وحدة تحكم أخيًرا، لحساب انحراف كل اتصال والضغوط القصوى. وفًقا لنتائج التجارب. وأفقًيا،تمكن الروبوت من التحرك بسالسة عمودًيا لذلك، ونتيجة <4d6963726f736f667420576f7264202d2033322d3431e3e5e4cf20d1d4cfed20e6d5c8c7cd> al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 16, no. 1, march, (2020) p. p. 3241 selection of optimum radiant barrier system (rbs) location in double skin ventilated roofs mohannad r. ghanim* sabah t. ahmed** *,**department of mechanical engineering/ university of technology/ baghdad/ iraq *email: mohannad.rushdi@gmail.com **email: sabahsmrm@yahoo.com (received 23 july 2019; accepted 24 november 2019) https://doi.org/10.22153/kej.2020.11.001 abstract double skin ventilated roof is one of the important passive cooling techniques that aims to reduce solar heat gain through roofs by reducing both the conduction and convection heat transfer from the roof to the ceiling of buildings. on the other hand, radiant barrier system (rbs) is very powerful in blocking the radiation heat transfer between the two skins. in this research, the effect of placing a thin layer of aluminium foil at different locations on the thermal insulation performance of a double skin ventilated roof model is investigated experimentally and the optimum location that transmits less heat flux from the lower skin is specified. the model is made of two parallel inclined galvanized steel plates. galvanized steel has been used in the roof construction of industrial buildings and storehouses in iraq. the radiant barrier is applied alternately, on the outer surface of the upper skin, on the inner surface of the upper skin, suspended in the airgap between the skins, and on the inner surface of the lower skin. these cases are considered as model a, model b, model c, and model d, respectively. it is found that the radiant barrier can block up to 78% of the heat in model a, 71% in model b, 94% in model c, and 91% in model d as compared with the basic model. since the radiant barrier in both model c and model d blocks almost the same amount of heat, the location of the radiant barrier in model d is chosen as the optimum radiant barrier location because this model is more practical. keywords: passive cooling, double skin roof, ventilated roof, radiant barrier system. 1. introduction roofs of buildings during summer are highly susceptible to the solar radiation and therefore cause a serious challenge of overheating. it was found that approximately 49% of the site’s electricity consumption has been used in air conditioning system [1]. double skin roof is a highperformance passive cooling system. it consists of two solid parallel layers; one at the top and the other at the bottom separated by airgap. the upper layer shields the lower one from direct solar radiation, and the airgap works as an insulation layer. the accumulated heat transferred from the upper layer can be removed by ventilating the airgap either naturally or by forced convection using mechanical fans. the ventilation of the gap by natural means needs a tilt angle of 10° to 30° in order to induce an upward flow of air due to buoyancy effect. air flow takes away the accumulated heat between the roofs skins and hence reduces the heat gain into the indoor environment. when the solar radiation falls on the upper roof plate, part of the radiation is absorbed due to the absorptivity of the surface and the other part is reflected. since the material of the plate is opaque, no radiation is transmitted through the roof. the absorbed heat is transferred by conduction through the solid plate and its temperature rises up then heat is transferred by both convection with the surrounding air and radiation with the surrounding surfaces as mohannad r. ghanim al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 3241 (2020) 33 illustrated in fig.1. both the conduction and convection heat transfer are reduced in this type of roofs. the radiation heat transfer can be reduced by using radian barrier systems (rbs). a radiant barrier as defined by the american society for testing and materials (astm) [2] is a thermal insulation material that consists of one or more reflective/low-emittance surfaces, such as metallic foil or metallic deposits, unmounted or mounted on substrates where the emittance is 0.10 or less, installed on or near a building component, facing enclosed air spaces. rbs intercepts the flow of radiant energy to and from the building component. one of the most common cheap rbs is the aluminium foil. a literature review shows that many investigations had been performed to study the effectiveness of rbs in blocking the radiation heat transfer through double skin ventilated roofs. in 2006, dimoudi et al. [3] tested a full-scale double skin horizontal roof component ventilated by a solar chimney under real climatic conditions by placing a rb immediately under upper roof skin. they found that the rb improves the performance of the roof remarkably since it keeps the lower skin at a temperature 5 k lower as compared to the one without rb. next year, w. puangsombut et al. [4] made an experimental investigation on free convection between two parallel plates heated from above and inclined at 15°. they examined two lower plates, namely radiant barrier and gypsum board. they found that the induced airflow rate through the channel is higher in the case of rb than the gypsum board while it could decrease the heat gain passing through the lower plate. in 2008, p.-c. chang et al. [5] studied the thermal insulation of a double skin roof prototype incorporating rbs in different locations. they concluded that the rbs attached to the interior surface of either roof plate or hung inside the duct, can enhance the thermal insulation of the basic prototype. in the same year, c.-m. lai et al. [6] made a similar study with different roof model and stated that installing a rbs on top of the bottom plate is very effective in preventing the roof heat from passing into the building. in 2011, s. roels and m. deurinck [7] investigated the effect of the emissivity of a roof underlay on the overall thermal behaviour of double skin inclined roofs by carrying out field testing, laboratory experiments, and a numerical investigation. they concluded that a low emissivity of the underlay reduces the heat gain to the indoor. in 2014, s. tong and h. li [8] built up a computational fluid dynamics (cfd) model to investigate the effect of the emissivity of the upper heated surface on the transferred heat flux from the lower skin. they found that the transferred heat flux reduces with the decrease of the thermal emittance. next year, d. li et al. [9] investigated numerically the effect of the absorption coefficient of the external surface on the thermal performance of double skin ventilated roofs. they found that increasing the absorption coefficient increases the average temperature of the lower skin. in 2018, m. ferreira et al. [10] presented a brief analysis on a radiant barrier applied on a single skin roof of a house. they concluded that the use of rbs is advantageous in attenuating the flow of heat through roofs. although many researches have been made on the effect of using radiant barriers on the insulation performance of double skin roofs, only p.-c. chang et al [5] have studied its performance on different locations. the aim of this research is to select the best radiant barrier location in a double skin roof model that is made of two parallel galvanized steel plates. galvanized steel has been used in the roof construction of industrial buildings and storehouses in iraq. the experimental rig as well as the measuring devices are presented in section 2. while the theoretical approach is explained in section 3. then our results will be discussed in section 4. fig. 1. heat transfer mechanism across a double skin ventilated roof. 2. the experimental setup the experimental rig is well designed and constructed for the purpose of the study. as illustrated in fig. 2, it consists mainly of four major parts, the stand, the roof model, the sun simulator, and the control panel. the upper part of the stand is movable to adjust the inclination angle of the roof. however, the angle in this study is fixed at 30°. the roof model includes two identical parallel galvanized steel sheets of 1.5 m long, 0.6 m wide and 1 mm thickness, as shown in fig. 3, and two mohannad r. ghanim al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 3241 (2020) 34 side wood plates of 1 cm thickness followed by a layer of 5 cm extruded polystyrene (xps) insulation board in order to neglect the flow of heat in the third direction. the airgap thickness is fixed at 0.04 m. the experiments are performed indoor to exclude the effect of wind and to avoid testing in variant sunlight conditions and standardize the testing environment. therefore, a sun simulator has to be used to simulate solar radiation. it is consisted of a set of eight 500w/2a/220v tungsten halogen lighting bulbs. tungsten halogen lamps have been used in the construction of commercial solar simulators [11]. they have also been used before by many researchers for the same purpose [6], [5], [12]. the electromagnetic wavelengths of these bulbs fall between 0.4 and 2.4 μm [5], [6], which are almost the same wavelengths of the solar radiation received on the ground. they are distributed in such a way that ensures almost uniform heat flux over the upper plate. a solidstate relay is connected to the lightings with a variable resistor for making the study at different radiation intensities. the electrical power is fed to the system from a stabilizer to provide a stable voltage and secure power supply and to avoid the variation in the radiation intensity. all the electrical accessories are fixed on a wood board and attached to the rig body, as shown in fig. 2a. a thin layer of aluminium foil is used as a radiant barrier due to its very low emissivity and low cost. the two plates are coated with rust-oleum matt black paint to maximize and standardize the emissivity of the surfaces and to simulate high emissivity slab materials such as wood, concrete, gypsum boa oxidised galvanized steel …etc. the aluminium foil is applied alternately on four different locations as illustrated in table 1. to reduce the contact resistance between the foil and the plate, toothpaste is used to stick the foil on the plate without air voids. (a) (b) fig. 2. the experimental rig. (a) photographic image. (b) isometric view. (a) (b) fig. 3. schematics of the experimental rig. (a) side view. (b) front view. mohannad r. ghanim al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 3241 (2020) 35 2.1 measurements all the measurements made are in terms of temperature, radiation intensity and heat flux. type-k calibrated thermocouples with an accuracy of 1°c are used to measure the temperature in twenty different places, four on each plate to estimate the average temperature of them and twelve thermocouples are distributed in the airgap along three imaginary planes (four thermocouples in each plane) to study the temperature distribution between the two plates, as shown in fig. 4. all thermocouples are connected to a digital thermometer type (tm-903a) from lutron electronic through a comark selector switch (20 channel). the radiation intensity fallen on the roof model is measured via a solar power meter model spm-1116sd with an error of ±10 w/m�. regarding the heat flux transferred through the upper and lower plates, it is measured using two items of phfs-01 heat flux sensor and its fluxdaq reader from fluxteq. all readings are taken when the system reaches a steady state condition (appendix a). the emissivity of the coated plates and the aluminium foil are measured at the iraqi ministry of science and technology by a tir100-2 emissometer and they found to be 0.792 and 0.006 respectively. 3. theory the rate of heat transfer per unit area (��) measured from the upper plate is equal to the rate of heat transfer by convection to the air in the cavity and the rate of heat exchange by radiation with the lower plate as follows [13]: �� � �� �� � � �� �� 1 � 1 �� � 1 … �1� where t and t� are the average temperature of the upper and lower plate respectively in k, σ is the stefan–boltzmann constant and it is equal to 5.67 × 10-8 w/m�k�, and ε and ε� are the inner surface emissivity of the upper and lower plate respectively. in the case of suspended rb (model c), equation (1) becomes [13]: �� � �� �� � � �� �� 1 � 1 �� 1 � ��. ��. 1 � ��.� ��.� … �2� where ε�. and ε�.� are the upper and lower surface emissivity of the rb respectivily. since the two plates are parallel, large, too close to each other, and facing each other, the view factor is assumed to be unity. t and t� are calculated by the appropriate numerical integration methods [14] (appendix b). table 1, the roof models based on the rb location. fig. 4. schematic of sensors distribution in the roof model. mohannad r. ghanim al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 3241 (2020) 36 4. results and discussion the effect of placing a thin layer of aluminium foil at different locations on the thermal insulation performance of a double skin ventilated roof model is investigated at 30° inclination angle, 4 cm airgap thickness for different radiation intensities (550, 700, 850, and 1000 w/m�), and the best location is determined. four locations are examined, namely, on the external surface of the upper plate, on the interior surface of the upper plate, suspended in the air gap between the plates, and on the internal surface of the lower plate. considering the roof model without rb as the basic model, these cases are termed as model a, model b, model c, and model d respectively. note that the emissivity of surfaces is assumed to be constant. the thermal behaviour of each model is discussed below: 4.1 the basic model it can be observed from fig. 5 that the temperature of the lower plate is higher than the temperature of the air in the channel which indicates that large amount of heat is exchanged by radiation between the high emissivity inner surfaces of the upper and lower plate. as a result, the heat flux transferred from the lower plate is too high due to the high temperature difference between the lower plate and the air under the plate, see fig. 6. therefore, the heat flux transferred from the upper plate is mainly transferred by radiation as illustrated in fig. 7. 4.2 model a as for model a in which the rb is attached to the outer surface of the upper plate, all temperatures are decreased considerably due to the high reflectivity of the aluminium foil. however, the temperature of the lower plate is still higher than the temperature of the air in the channel (fig. 5) which means that heat exchange by radiation between the two plates is still high and hence the heat flux is also high. the heat transferred from the upper plate by radiation is dominating as compared to the convection because the temperature difference between the plate and the air in the channel is low, as shown in fig. 7. placing the aluminium foil in this position blocked 78% of the heat transferred through the roof model as compared with the basic model (fig. 6). 4.3 model b attaching the rb to the inner surface of the upper plate increases the temperature of the plate to the highest degree as the rb prevents the heat exchange by radiation with the lower plate, and hence the heat is accumulated in the material. therefore, the temperature of air layer adjacent to the foil is rapidly increased due to the high temperature difference between the air and the upper plate, as shown in fig. 5. the rb in this model blocked 71% of the heat transferred through the roof model (fig. 6). 4.4 model c when the rb is suspended in the airgap between the two plates (model c), the temperature of the upper plate is also high because its heat is only transferred by convection. the heat flux from the lower plate is the least in this case since the rb blocked 94% of the heat transferred through the roof model, as shown in fig. 6. the rb split the air gap into two separated regions blocking both the convection and radiation heat transfer from the upper plate to the lower plate. it works as a radiation shield [15] because two additional low emissivity surfaces is added, hence radiation has to be exchanged first between the inner surface of the upper plate and the upper surface of the rb, then between the lower surface of the rb and the inner surface of the lower plate. however, placing the rb in this location is hard to be fulfilled practically. mohannad r. ghanim al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 3241 (2020) 37 fig. 5. temperature profiles along the length of the channel at 1000 �/�� radiation intensity. 20 30 40 50 60 70 80 90 100 110 120 130 0 50 100 150 t em p er at u re ° c length cm basic model 20 30 40 50 60 70 80 90 100 110 120 130 0 50 100 150 t em p er at u re ° c length cm model a 20 30 40 50 60 70 80 90 100 110 120 130 0 50 100 150 t em p er at u re ° c length cm model b 20 30 40 50 60 70 80 90 100 110 120 130 0 50 100 150 t em p er at u re ° c length cm model c 20 30 40 50 60 70 80 90 100 110 120 130 0 50 100 150 t em p er at u re ° c length cm model d mohannad r. ghanim al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 3241 (2020) 38 fig. 6. the transferred heat flux through the lower plate. fig. 7. the transferred heat flux through the upper plate. 4.5 model d theoretically, this model is the same as model b. however, it transmitted less heat than model b. one of the reasons could be due to the variation of the surface emissivity with temperature. 91% of the heat has been blocked in this model which is almost the same as the heat blocked in model c, as shown in fig. 6. furthermore, the rb in this case can be applied practically by applying a thin layer of a reflective underlay or by applying reflective paints on the inner surface of the lower skin. therefore, this model is the most appropriate one. the only disadvantage of this model as well as model a is the accumulation of dust over a period of time which could decrease the performance of the rbs by increasing its emissivity. these results are in agreement with p.-c. chang et al. [5], who have examined the thermal insulation performance of a different double skin roof model that is consisted of a steel wave plate as the upper skin and reinforced concrete slab as the lower skin incorporating rbs at different locations. 5. conclusion an experimental investigation is performed to study the effect of placing a thin layer of aluminium foil at different locations on the thermal insulation performance of double skin ventilated roof model at different radiation intensities. it is found that the rb can block up to 78% of the heat in model a, 71% in model b, 94% in model c, and 91% in model d as compared to the basic model. it can be concluded that placing the rb in the airgap between the plates which is the case in model c blocks the most radiation heat exchange between the plates. however, this model is hard to be applied practically. since model d in which the rb is applied on the inner surface of the lower plate blocks almost the same amount of heat as model c, the location of the rb can be chosen as the best rb location. the only disadvantage of this model (as well as model a) is the accumulation of dust over a period of time which could decrease the performance of the rbs by increasing its emissivity. this research highly recommends applying a thin layer of a reflective underlay or reflective paints on the inner surface of the lower roof skin which can enhance the thermal insulation performance of the roof. appendix a estimation of steady state condition three different criteria are considered to estimate the steady state condition, these are the average temperature of the upper and lower plate, as well as the bulk temperature of the air cavity (appendix b). as depicted in fig. a.1, less than an hour is sufficient for the system to be at steadystate condition. any increase in temperature after that time is due to the increasing temperature of the environment. therefore, all readings are taken after one hour from the application of heat. mohannad r. ghanim al-khwarizmi engineering journal, vol. 15, no. 4, p.p. 3241 (2020) 39 fig. a.1: the mean temperatures of the upper and lower plates and the bulk temperature of air as a function of time. appendix b numerical integration the appropriate integration method for estimating the average temperature of the upper and lower plates is simpson's 3/8 rule as follows [14]: � � � . 3� .� 3� .� � .� 8 � .1� �� � �!. 3�!.� 3�!.� �!.� 8 � .2� as for the bulk temperature of air, it is estimated by first integrating the vertical five points of each section using boole's rule, then integrating the resulting points by simpson's 3/8 rule as follows [14]: �" � 7� . 32��. 12��. 32��. 7�!. 90 � .3� �"� � 7� .� 32��.� 12��.� 32��.� 7�!.� 90 � .4� �"� � 7� .� 32��.� 12��.� 32��.� 7�!.� 90 � .5� �"� � 7� .� 32��.� 12��.� 32��.� 7�!.� 90 � .6� �" � �" 3�"� 3�"� �"� 8 � .7� notation ) radiation intensity * the channel length �+ the heat flux from the lower plate �� the heat flux transferred by convection �,-. the rate of heat exchange by radiation �� the heat flux from the upper plate / the spacing between the upper and lower plates � the temperature of the upper plate �� the temperature of the lower plate �" the bulk temperature of air �0 the external temperature of air greek letters stefan–boltzmann constant � the inner surface emissivity of the upper plate �� the inner surface emissivity of the lower plate ��. the upper surface emissivity of the rb ��.� the lower surface emissivity of the rb 1 the inclination angle of the roof model from the horizontal 6. references [1] a. a. m. saleh, “energy saving of heat gain by using buried pipe inside a roof energy saving of heat,” al-khwarizmi eng. j., vol. 11, no. 1, pp. 32–39, 2015. 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[15] j. p. holman, heat transfer. mcgraw hill higher education, 2010. )2020( 3241، صفحة 1العدد ، 16دجلة الخوارزمي الهندسية المجلم مهند رشدي غانم 41 في السقوف المهواة مزدوجة الطبقة لنظام الحاجز االشعاعياختيار افضل موقع صباح طارق احمد** مهند رشدي غانم* *،**قسم الهندسة الميكانيكية/ الجامعة التكنولوجية mohannad.rushdi@gmail.com *البريد االلكتروني: sabahsmrm@yahoo.com **البريد االلكتروني: الخالصة عملية انتقال السقوف المهواة مزدوجة الطبقة هي احد اهم تقنيات التبريد المستتر المستخدمة لتقليل الحمل الحراري الشمسي من السقوف من خالل تقليل شعاع بين طبقتي هذا النوع الحرارة بواسطة كالً من التوصيل والحمل. من ناحية اخرى، حواجز االشعاع تعتبر من الوسائل الفعالة في منع انتقال الحرارة باال مزدوج الطبقة من السقوف. في هذا البحث، تم دراسة تاثير وضع طبقة من رقائق االلمنيوم في مواقع مختلفة على فعالية العزل الحراري لنموذج سقف مهوى الحديد المغلون كان وال يزال يستخدم في تسقيف وتم تحديد افضل موقع لها. النموذج مصنوع من طبقتين متوازيتين ومائلتين من صفائح الحديد المغلون. لداخلي للطبقة البنايات الصناعية والمخازن في العراق. تم االختبار بوضع الحاجز االشعاعي بالتبادل على السطح الخارجي للطبقة العلوية، على السطح ا ، والنموذج c، النموذج b، النموذج aية. تم اعتماد تسمية هذه الحاالت بالنموذج العلوية، معلق في الهواء بين طبقتي السقف، وعلى السطح الداخلي للطبقة السفل d في النموذج %٧٨، على التوالي. حيث وجد ان الجدار االشعاعي بامكانه حجبa ،في النموذج %٧١b ،في النموذج %٩٤c ،في النموذج %٩١d بامكانهما حجب نفس المقدار من الحرارة تقريباً، تم اختيار موقع الحاجز dو النموذج cلنموذج اذا ما تم مقارنتها مع النموذج االساسي. بما ان كال من ا كافضل موقع له وذلك كونه عملياً اكثر. dاالشعاعي في النموذج this is an open access article under the cc by license: effect of heat treatment on the microstructure, impact toughness and hardness of high-chromium white cast iron with added niobium and manganese minerals ali hatra1, ahmad salamah2 and nassim aldaher3* 1,2department of production and design engineering, faculty of mechanical and electrical engineering, university of tishreen, lattakia, syria 3department of mechanics, faculty of mechanical and electrical engineering, university of tishreen, lattakia, syria *corresponding author’s email: nassimaldaher111@gmail.com (received 11 november 2024; revised 4 february 2025; accepted 9 february 2025; published 1 march 2025) https://doi.org/10.22153/kej.2025.02.001 abstract in this work, manganese and niobium were added to high-chromium white cast iron, from which drilling and grinding tools were made. two melts with different proportions of manganese and niobium (manganese 2.75% and niobium 0.49%, manganese 3.5% and niobium 1.1%) were used. high-chromium white cast iron is considered one of the most important alloys in heavy-duty applications, and its properties are affected by the added alloying elements and heat treatment. niobium can increase corrosion resistance and hardness, form carbides, enhance thermal conductivity and improve response to heat treatment. as for manganese, it can increase impact toughness, remove oxygen from iron oxide and reduce flexibility. the heat treatment was carried out in accordance with two different programmes: 1heating to 950 °c with a holding period of 2 h and cooling in atmospheric air; 2heating to 960 °c with a holding period of 20 min, then cooling in the oven and returning to 425 °c for 3 h. the mechanical properties, such as wear resistance, impact durability and hardness, before and after heat treatments 1 and 2 were compared. keywords: wear; impact toughness; hardness; grinding; high-chromium white cast iron; cracking. 1. introduction high-chromium white cast iron alloys are used in applications that require high hardness, such as in our study on the teeth of excavators and crusher hammers. the american society for testing and materials classified them on the basis of the percentage of chromium and the total percentage of impurities less than 0.15% (astm a532-75a). the density of high-chromium white cast iron is 7.4 gr/cm3. below are the most important mechanical properties of the alloy and the influence of niobium and manganese. table 1, mechanical properties of high-chromium white cast iron 1380–1965 compressive yield limit stress mpa 550–775 harshness hv 120–125 impact energy j 0.0655–0.985 wear rate al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 21, no. 1, march, (2025), p p. 7388 mailto:nassimaldaher111@gmail.com https://doi.org/10.22153/kej.2025.02.001 https://doi.org/10.22153/kej.2025.02.001 ali hatra al-khwarizmi engineering journal, vol. 21, no.1, pp. 7388 (2025) 74 table 2, properties of nb, mn and their effect on white cast iron. the importance of the research comes from the significance of this type of cast iron in the mining industry, infrastructure and various industrial and military fields and the necessity of replacing breaking and drilling tools due to the force of impact and high wear during work. therefore, increasing the actual life of tools in heavy-duty applications by enhancing the mechanical properties of the alloy is necessary. the goal of this research is to determine the heat treatment that achieves the best properties in terms of hardness values and impact toughness for highchromium white cast iron with added manganese and niobium, which differs from astm a532 classifications. on this basis, crusher hammers and excavator teeth are made by heat treatment in accordance with two different programmes. in 1999, guan compared the effects of fermentation, tempering and reflux on highchromium white cast iron, found that the fermentation samples had lower hardness and fracture toughness values than the tempering and reflux samples and proved that the reflux samples were better [1]. in 2001, arikan’s research tackled the addition of titanium to high-chromium white cast iron, leading to the formation of fine grains, which turned out to be titanium carbides. the wear resistance of the alloy increased by 30% after ti addition at a rate of 0.38% and quenching. after the review treatment, the properties decreased. their values during watering were studied. [2] in 2007, wu’s research resulted in the following: the tic carbide molecule in high-chromium cast iron acts as crystallisation seeds for primary m7c3 carbides by determining the value of the contrast between the dimensions of their lattice structures. if it is smaller than 6%, then the ability to form crystallisation seeds is high; if it is between 6% and 12%, then the ability is less; if the variation is greater than 12%, then the formation is impossible [3]. in 2008, s. zic tried to form an alloy of highmanganese steel and high-chromium white cast iron but did not obtain optimal results because of the large difference in the temperature of the hadfield steel after casting and the font temperature when casting [4]. in 2012, studnicki’s research resulted in a new method for researching the crystallisation process using three tests. this method enabled the characterisation of the sensitivity of cast iron to the cooling kinetics [5]. in 2013, parente applied a suitable heat treatment to two products of highand low-carbon white cast iron to obtain a product with great resistance and durability. he found that the compressive behaviour at 500 °c was favourable for these products, which exhibited high compressive strength with ductility, and led to an increase in chromium and carbon [6]. in 2014, agunsoyer determined that when highchromium white cast iron was hardened with oil, the fracture toughness was constant between the range of 2.4% and 2.6% carbon. the fracture toughness at a high carbon percentage was controlled by an isolated carbide network that represented weak links in the microstructure. these weak bonds induced dislocations and weakened the material. [7] in 2017, m.h. ford classified types of carbides formed in high-chromium white cast iron during crystallisation. they determined that primary carbides formed at a carbon percentage higher than 4% and a temperature higher than the eutectic line, eutectic carbides formed at the eutectic line, and secondary carbides resulted from the transformation of austenite into martensite. the excess carbon was transformed into carbides with a small granular structure [8]. in 2019, b hinckley studied two alloys of highchromium white cast iron that were heat-treated and concluded that increasing the carbon percentage from 3% to 5% led to the ground changing from a desirable structure containing martensite to an undesirable structure containing pearlite. he element density melting temperature °c effect on white cast iron niobium (recommendation) 8.57 gr/𝑐𝑚3 2480 it increases wear resistance and hardness, enables the formation of carbides, enhances thermal conductivity and improves response to heat treatment. manganese 7.21 gr/𝑐𝑚3 1244 it increases impact durability, removes oxygen from iron oxide and reduces flexibility. ali hatra al-khwarizmi engineering journal, vol. 21, no.1, pp. 7388 (2025) 75 indicated that the alloy containing a high percentage of chromium prevented pearlite transformation and facilitated martensitic transformation [9]. s lung formed high-chromium white cast iron cast at different temperatures. based on the resulting properties and structures, casting at 1450 °c achieved better wear resistance and impact durability than other processes [10]. abaad k and walaa a concluded that heating high-chromium white cast iron to 900 °c for 30 min, then cooling with oil and returning to 550 °c for 4 h improved its hardness, durability and wear resistance [11]. in 2020, albetar abaad k concluded that impact toughness and wear resistance were increased with the addition of titanium to high-chromium white cast iron by die casting [12]. m biere increased the percentage of silicon in high-chromium white cast iron, departing from the astm classifications, and reached good hardness values. however, the impact toughness fell below the astm values [13]. kh abdel aziz showed that, through the heat treatment of high-chromium white cast iron, a secondary quasi-spherical carbide formed within the primary austenitic ground, which later turned into martensite, and the hardness increased [14]. hua nan liu formed a test alloy containing 40% chromium and 9% niobium for wear resistance, compared it with a white cast iron alloy with 25% chromium and concluded that the test alloy had a wear rate of 36% in comparison with the white cast iron alloy [15]. nhk luan studied the effect of adding vanadium and niobium on the abrasive and impact wear properties of white cast iron with 16% cr and 3% mo, then conducted heat treatment of the samples. the researcher concluded that spherical carbides formed in the structure and increased the stability of martensite in the floor. the resistance to abrasive wear was increased, whereas the resistance to impact wear was reduced. in harsh conditions, self-recovery of martensite in the floor occurred owing to the impact energy of the abrasive medium, which increased impact wear [16]. agustina guitar found that heat treatment tempering of highchromium (26%) white cast iron increased the precipitation of m23c6 sc carbides because of the austenitic/martensitic transformation, and the results showed an improvement in the hardness of the floor [17]. in 2022, luan nh studied the role of the floor structure in resisting impact wear of high-chromium (27%) white cast iron samples by conducting heat treatment. the researcher concluded that increasing the remaining austenite and tempering improved the softness of the structure due to the return of martensite, which limited the wear rate [18]. in 2023, c le nué studied the effect of heat treatment on the hardness and ground structure of high-chromium (16.5%) white cast iron. the researcher concluded that the microstructure changed into a homogeneous structure with m23c6 carbides in the ground that completely transformed into martensite upon cooling. he also observed the formation of m7c3 carbides upon cooling, and 1000 °c improved the hardness [19]. in 2024, ngo hk studied the effect of heat treatment on the wear resistance of high-chromium (24% and 27%) white cast iron. the researcher showed the formation of lamellar pearlite after casting in the microstructure of samples containing 24% cr after crystallisation and the formation of granular pearlite. after the fermentation treatment and upon tempering, the amount of remaining austenite increased. the researcher concluded that wear resistance was affected by grounding, eutectic carbides and strain hardening [20]. franco studied the surface wear resistance of high-chromium white cast iron (2.8% c, 14% cr) through steel ball blasting, and the results showed that the surface wear mechanism was related to the microstructure consisting of austenite and martensite. the researcher heated the white cast iron up to 990 °c, and this process resulted in a high percentage of austenite, martensite and secondary carbides being distributed, which increased the wear resistance. at 1050 °c, the amount of martensite, austenite and carbides decreased, which implied an increase in the wear rate [21]. chabak investigated the effect of tempering temperature on the wear resistance of aluminium oxide for various samples of cast iron containing boron. the researcher found that the samples heated to 1200 °c for 4.5 h had enhanced wear resistance. with the increase heating temperature, the wear rate was reduced by about 3 times [22]. xiong studied the effect of retention time during heat treatment on the microstructure and mechanical properties of high-chromium white cast iron and found that the hardness is closely related to the size and cross section of secondary carbides in the ground. the treated sample was heated to 1000 °c for 1 h, resulting in samples with the highest hardness. the hardness decreased in samples with large carbides. the hardness values of samples treated for 14 h were lower than those treated for 10 min. at 1050 °c, the size and density of secondary carbides increased with increasing retention time [23]. the reference studies stressed the importance of studying high-chromium cast iron in heavy-duty applications given its high hardness, but it suffers from low impact toughness. therefore, we will try to improve the hardness and impact toughness by ali hatra al-khwarizmi engineering journal, vol. 21, no.1, pp. 7388 (2025) 76 adding manganese and niobium in different proportions, then carrying out heat treatments. 2. research materials and methods 1. foundry-master 01m0026 optik 01m0026 spectrograph 2. wear testing machine for testing samples (astm g65-94) 3. impact tester (charpy, astm e23) and hardness tester (vickers, gnehm harteprufer) for testing samples 4. linn electro therm heat treatment furnace 5. optical microscope 2.1 stages of work we obtained samples of high-chromium white cast iron and conducted spectroscopic analysis of them to determine their class in accordance with the american association. then, we added manganese and niobium in different proportions and conducted heat treatment on the basis of two different programmes. afterwards, we performed hardness, wear resistance and impact toughness tests of the samples before and after heat treatment. table 3, samples of high-chromium white cast iron classified in accordance with astm a532 [12]. wt% cu mo ni cr si mn c 1.2 1.0 0.5 11–14 1.0 1.5 2.4–2.8 12% cr a ii 1.2 3.0 0.5 14–18 1.0 1.5 2.4–2.8 15% cr-mo-lc b ii 1.2 3.0 0.5 14–18 1.0 1.5 2.8–3.6 15% cr-mo-hc c ii 1.2 1.5 1.5 18–23 1.0 1.5 2.0–2.6 20% cr-mo-lc d ii 1.2 2.0 1.5 18–23 1.0 1.5 2.6–3.2 20% cr-mo-hc e ii 1.2 1.5 1.5 22–25 1.0 1.5 2.3–3.0 25% cr a iii samples of high-chromium white cast iron prepared with the addition of manganese and niobium are listed in table 3. table 4 shows the results of spectroscopic analysis using the spectroscopy device. table 4, spectral analysis of samples manufactured from high-chromium white cast iron, to which 2.75% manganese and 0.49% niobium were added. fe c si mn p s cr 1 64.111 2.800 0.587 2.750 0.001 0.001 24.227 2 64.110 2.799 0.588 2.750 0.001 0.001 24.239 average 64.110 2.800 0.588 2.750 0.001 0.001 24.288 mo ni al co cu nb ti 1 1.478 1.503 0.123 0.052 1.203 0.490 0.0075 2 1.485 1.501 0.117 0.050 1.202 0.492 0.074 average 1.497 1.502 0.120 0.051 1.202 0.491 0.0074 v w pb sn b ca zr 1 0.005 0.001 0.000 0.005 0.002 0.004 0.001 2 0.003 0.001 0.000 0.003 0.002 0.002 0.001 average 0.004 0.001 0.000 0.004 0.002 0.003 0.001 as bi 1 0.000 0.000 2 0.000 0.000 average 0.000 0.000 table 5, ali hatra al-khwarizmi engineering journal, vol. 21, no.1, pp. 7388 (2025) 77 spectral analysis of samples manufactured from high-chromium white cast iron, to which 3.5% manganese and 1.1% niobium were added. fe c si mn p s cr 1 62.078 2.799 0.987 3.501 0.001 0.001 24.795 2 62.079 2.803 0.986 3.501 0.001 0.001 24.793 average 62.078 2.801 0.986 3.501 0.001 0.001 24.794 mo ni al co cu nb ti 1 1.487 1.502 0.148 0.053 1.230 1.195 0.0073 2 1.487 1.503 0.149 0.051 1.226 1.005 0.0074 average 1.487 1.503 0.149 0.052 1.228 1.100 0.0073 v w pb sn b ca zr 1 0.005 0.001 0.000 0.005 0.002 0.004 0.001 2 0.003 0.001 0.000 0.003 0.002 0.002 0.001 average 0.004 0.001 0.000 0.004 0.002 0.003 0.001 as bi 1 0.000 0.000 2 0.000 0.000 average 0.000 0.000 in the first smelting, the percentage of manganese was 2.75%, and that of niobium was 0.49%. in the second smelting, manganese was 3.5%, and niobium was 1.1%. 2.1.1 heat treatment eight samples (three samples for impact, three samples for wear and hardness and two samples for microstructure) were taken after casting for heat treatment 1. another eight samples (three samples for impact, three samples for wear and hardness and two samples for microstructure) were taken after casting for heat treatment 2. fig. 2. heat treatment furnace. table 6, heat treatment applied. applied heat treatment programmes 1heating to 950 °c with a holding period of 2 h and cooling in atmospheric air 2heating to 960 °c with a holding period of 20 min, then cooling in the oven and returning to 425 °c for 3 h 2.1.2 optical microscope the microscope consists of two sets of lenses at the ends of a tube that is the body of the microscope. the lens at the beginning of the tube, from which viewing is achieved, is called the ocular lens at the top, whilst the lens at the end of the body that is close to the test sample is called the body lens at the bottom. microscopic examination of the samples was performed before and after heat treatment, as described in the following steps: 1. grinding using silicon carbide grinding paper with different degrees of fineness (120, 320, 500 and 1000 grit/cm2) 2. polishing using an alumina solution of 0.3 µm and a special polishing cloth, washing the samples with distilled water and alcohol and drying them after each stage ali hatra al-khwarizmi engineering journal, vol. 21, no.1, pp. 7388 (2025) 78 3. etching using 2% nital solution by immersing the sample and then washing the sample with distilled water and alcohol 4. using an optical microscope (widmps 51) to determine the microscopic structure of the samples fig. 3. hund h600 optical microscope. 2.1.3 hardness test the hardness test was carried out with reference to the approach of vickers, in which the sample was placed on an anvil and gradually raised using a square diamond pyramid until it was in direct contact with the point of the notching tool. a load of 30 kg was gradually applied to the notching tool and then removed. fig. 4. vickers test. 2.1.4 wear test sand–rubber disk test was performed by placing a sample with dimensions of 25×76 (mm2) and a thickness of 3.2–12.7 mm in front of a stream of sand so that the sample was pressed with a force of 130 n towards the rubber disk that was rotating at a speed of 2000 rpm. from the difference in weight of the sample before and after the test, the wear rate was determined. fig. 5. wear test. ali hatra al-khwarizmi engineering journal, vol. 21, no.1, pp. 7388 (2025) 79 2.1.5 impact test and results the impact samples were formed with a vshaped notch in accordance with the charpy test. impact toughness was measured, i.e. the impact toughness at which the sample broke after a shock was directed to it on the opposite side of the face that contained the notch. a b fig. 6. a-impact test, b-one of the impact specimens. the following figures show the microscopic structure of the samples before and after heat treatment at 400 magnifications. \ fig. 7. resulting microstructure of the first case sample, high-chromium white cast iron with 0.491% nb and 2.75% mn, without heat treatment. ali hatra al-khwarizmi engineering journal, vol. 21, no.1, pp. 7388 (2025) 80 fig. 8. resulting microstructure of the first case sample, high-chromium white cast iron with 0.491% nb and 2.75% mn, after heat treatment 1. fig. 9. resulting microstructure of the first case sample, high-chromium white cast iron with 0.491% nb and 2.75% mn, after heat treatment 2. fig. 10. resulting microstructure of the second case sample, high-chromium white cast iron with 1.1% nb and 3.5% mn, without heat treatment. fig. 11. resulting microstructure of the second case sample, high-chromium white cast iron with 1.1% nb and 3.5% mn, after heat treatment 1. ali hatra al-khwarizmi engineering journal, vol. 21, no.1, pp. 7388 (2025) 81 fig. 12. resulting microstructure of the second case sample, high-chromium white cast iron with 1.1% nb and 3.5% mn, after heat treatment 2. 3. results and discussion tables 7 and 8 show the results of the hardness test before and after heat treatments. table 7, hardness test values for samples added with 2.75% manganese and 0.49% niobium. condition value arithmetic average without treatment 693-694-696 hv 696 hv treatment 1 786-785-784hv 785 hv treatment 2 911-913-906 hv 910 hv table 8, hardness test values for samples added with 3.5% manganese and 1.1% niobium. condition value arithmetic average without treatment 712-710-714 hv 710 hv treatment 1 797-798-796 hv 797 hv treatment 2 926-922-924 hv 922 hv table 9, wear test results from the case of high-chromium white cast iron with 0.491% niobium and 2.75% manganese. treatment 1 treatment 2 without treatment mass before test gr 89.5479 90.2196 88.9564 89.6748 88.4545 88.1967 mass after test gr 89.4941 90.1659 88.9026 89.6231 88.3975 88.1402 mass loss gr 0.0538 0.0536 0.0537 0.0516 0.0569 0.0564 density gr/cm3 7.34 7.34 7.34 7.34 7.34 7.34 volume loss mm3 x 1000 7.3379 7.3092 7.3236 7.0364 7.7544 7.6969 wear rate = volume loss / 1436 0.00511 0.00509 0.0051 0.0049 0.00540 0.00536 average wear rate 0.00510 0.0050 0.00542 ali hatra al-khwarizmi engineering journal, vol. 21, no.1, pp. 7388 (2025) 82 table 10, wear test results from the case of high-chromium white cast iron with 1.1% niobium and 3.5% manganese. treatment 1 treatment 2 without treatment mass before test gr 91.0050 89.9966 90.0012 89.6521 89.1213 89.0912 mass after test gr 90.9516 89.9428 89.9495 89.6025 89.0636 89.0350 mass loss gr 0.05333 0.05375 0.5164 0.4953 0.0567 0.0562 density gr/cm3 7.34 7.34 7.34 7.34 7.34 7.34 volume loss mm3 x 1000 7.2661 7.3236 0.7036 6.7492 7.7113 7.682 wear rate = volume loss / 1436 0.00506 0.00510 0.0049 0.0047 0.00537 0.00535 average wear rate 0.00508 0.0048 0.00536 table 11, impact test values for samples added with 2.75% manganese and 0.49% niobium. condition value arithmetic average treatment 1 175-176-174 j 175 j treatment 2 181-180-180 j 181 j without treatment 144-145-146 j 145 j table 12, impact test values for samples with 3.5% manganese and 1.1% niobium added. condition value arithmetic average treatment 1 178-180-182 j 180 j treatment 2 189-190-191 j 190 j without treatment 157-158-156 j 157 j the following figure shows a comparison of the values: 1. samples with 0.491% nb and 2.75% mn without treatment 2. samples with 0.491% nb and 2.75% mn under treatment 1 3. samples with 0.491% nb and 2.75% mn under treatment 2 4. samples with 1.1% nb and 3.5% mn without treatment 5. samples with 1.1% nb and 3.5% mn under treatment 1 6. samples with 1.1% nb and 3.5% mn under treatment 2 (a) ali hatra al-khwarizmi engineering journal, vol. 21, no.1, pp. 7388 (2025) 83 (b) (c) fig. 13. (a) hardness hv, (b) wear rate, and (c)impact durability with heat treatment, from the values in the tables, the impact resistance and hardness (wear resistance) increased, especially in the second case. by heat treatment 1, the shape of the eutectic cementite and secondary carbide was transformed into a circle. through hardening and reflux in treatment 2, the pearlite decreased, and the purity of the microstructure increased by adding nb and mn. treatment 2 achieved the best values of hardness, wear resistance and impact toughness in the two melts. the addition of niobium and manganese controlled the formation of carbides m2c and m6c. the application of the gradual heat treatment programme 2 led to a saving in heating time and temperature and thus a saving in economic cost because we did not have to open the oven door and take out the piece. the results obtained in terms of hardness, wear resistance and impact durability were better than the results in [11], [12]. based on the microstructures without heat treatment, the resulting structure was not rough and did not contain agglomerates because manganese and niobium reduced the size of primary and eutectic carbides. the hypoeutectic microstructure was evident, which resulted from a small section of supraeutectic dendrite austenite and m7c3 carbides. carbide was also present in the form of a sharp tooth because of the presence of large pieces of supraeutectic austenite, which became smaller upon cooling (due to the heat released when supraeutectic austenite was formed), forming sharp carbides. niobium carbide was further formed, which precipitated in the liquid melt and reduced the amount of carbon in the ground, creating m7c3 carbides and activating nuclei that formed austenite branches and dendrites. as a result, the size of the carbide decreased, and the smoothness of the microstructure increased. when manganese was added to the samples, the ground was made of martensite and austenite ali hatra al-khwarizmi engineering journal, vol. 21, no.1, pp. 7388 (2025) 84 because manganese helped stabilise the austenite. the concentration of carbon and alloying elements, especially chromium, in the austenitic floor increased, which prevented the precipitation of pearlite, and the starting point of the martensitic transformation (ms) decreased. at the beginning of the melting of the samples (with moderate carbon and manganese content), groups of granular eutectic cementite appeared in the lattice structure, which were regularly distributed in the austenitic floor. as the content of niobium and manganese increased, large numbers of secondary carbides separated in the ground, their shape being approximately spherical. we observed a small amount of pearlite in the floor. the structure of all samples contained mainly austenite and a small amount of micrometre-sized martensite near the carbides in the ground. the width of the martensite increased in the ground, and the shape of the eutectic cementite and secondary carbide turned into round after heat treatment of the samples, which led to an increase in hardness and wear resistance. the carbides in the samples consisted of primary carbide m7c3, carbide m2c and eutectic cementite (fe, mn)3c in the ground. the ground structure was a mixture of austenite, pearlite and martensite. according to many studies, crystallisation takes place first from the molten state to m7c3 and molten and from the molten state to eutectic (austenite + m7c3/m23c6). a small amount of m2c carbide was formed at a late stage of crystallisation, mainly due to the addition of manganese, which improved hardness and thus wear resistance. at the crystallisation temperature of about 800 °c, a small amount of m23c6 carbide was formed around m7c3 carbide. precipitated carbide m2c, rich in nb and mn, formed at the end of the crystallisation process. the chemical composition of the samples changed with the variation in niobium content. when the niobium percentage reached 1%, the ground structure comprised austenite and martensite. therefore, the ground of high-chromium white cast iron was mainly composed of austenite, martensite and eutectic cementite secondary carbide m6c. 4. conclusions unlike the reference studies, we used heat treatment and reflux. guan also compared the effects of fermentation, tempering and reflux on high-chromium white cast iron [1]. we added important alloying elements such as niobium and manganese. arikan added titanium to highchromium white cast iron [2], which led to the formation of fine grains, i.e. titanium carbides. we obtained better mechanical properties after adding manganese and niobium. in our study, the carbide molecule tic acted as crystallisation seeds for primary m7c3 carbides by determining the value of the contrast between the dimensions of their lattice structures, similar to what wu obtained in the study .[3] by adding manganese and niobium, we obtained much better results than the study of s. zic [4], who tried to form a metal alloy from high-manganese steel and high-chromium white cast iron. he did not obtain optimal results owing to the high difference in the temperature of the hadfield steel after casting and the font temperature when pouring. in our research, we did not address new methods of crystallisation, as studnicki did [5]. in comparison with the study in [6], we performed heat treatment, but with the addition of effective alloying elements, and observed the resulting microstructures. agunsoyer [7] showed that when high-chromium white cast iron was hardened with oil, the fracture toughness was between the range of 2.4% and 2.6% carbon. in our research, we quenched it in atmospheric air and the oven without resorting to water or oil cooling medium. m.h. ford [8] examined the types of carbides formed in highchromium white cast iron during crystallisation and classified them. likewise. we discussed the types and nature of carbides in the microstructures. in terms of heat treatment and the resulting structures, the explanation of the resulting structures of eutectic, niobium carbides and hypoeutectic austenite was similar to that in [9]. in [10], s lung formed high-chromium white cast iron cast at different temperatures and studied the resulting properties and structures. in our research, we cast at a specific temperature on the basis of the state of the melt and the alloy additives we used. we also carried out heat treatment with atmospheric air without using oil, compared with abaad k and walaa a [11] who heated high-chromium white cast iron to 900 °c for 30 min. then, cooling with oil and returning at 550 °c for 4 h improved hardness, durability and wear resistance. albetar abaad k concluded that impact durability and wear resistance were increased with the addition of titanium to high-chromium white cast iron by casting in metal moulds [12]. this approach differed from our research approach of casting in sand ali hatra al-khwarizmi engineering journal, vol. 21, no.1, pp. 7388 (2025) 85 moulds and adding niobium and manganese, not titanium, and we obtained better results in terms of mechanical properties. in [13], m biere increased the percentage of silicon in high-chromium white cast iron, deviating from astm classifications, and reached good values for hardness, but the impact strength decreased from the values in astm. as for our research, it dealt with the addition of niobium and manganese. in the study of kh abdel aziz [14], through the heat treatment of high-chromium white cast iron, secondary semispherical carbides were formed within the primary austenitic ground, which later transformed into martensite. in [15], hua nan liu formed a test alloy containing 40% chromium and 9% niobium for resistance to normal wear, compared it with the white cast iron alloy including 25% chromium and concluded that the test alloy had a wear rate of 36% relative to the white cast iron alloy. we followed an experimental approach of adding niobium and manganese in different proportions and performing heat treatment in accordance with two different programmes to improve the properties of shock and harshness. in [16], ngo studied the effect of heat treatment on the wear resistance of high-chromium cast iron. he showed the effect of this treatment on surface hardening and wear behaviour through a floor rich in eutectic carbides. the wear rate was determined to be dependent on the degree of strain hardening during work. our research did not cover surface hardening but relied on the results of tests. le nué studied the evolution of the structure upon heat treatment, which led to the formation of an almost homogeneous structure that turned into martensite upon cooling. various carbides were formed by carbon and heating to temperatures above 1000 °c [17] . in [18], luan presented research on the role of the ground structure in resisting impact wear for cast iron that contained 27% chromium. heating treatment to 1223 k increased the size of the initial martensite, and the wear rate reached its maximum at 60 degrees. when heated to 1423 k, the ground, which was mostly austenite, showed the maximum wear rate at 45 degrees due to the transformation from unstable austenitic to martensite by stress and impact. the hardening resulting from martensite induced by stress interfered with the softening caused by initial martensite recovery, which contributed to reducing the corrosion rate. on the contrary, in our research, we conducted two heat treatments and added the elements manganese and niobium. in [19], luan nh showed the effect of vanadium and niobium on the impact and abrasion wear properties of white cast iron containing 16% chromium and 3% molybdenum. spherical carbides (mc) were formed through the incorporation of nb and v, in addition to martensite, in the more stable ground, which improved wear resistance. as mentioned, our research focused on the addition of magnesium and niobium and then heat treatments. guitar [20] studied the effect of thermal processes and chemical composition on carbide precipitation. after heat treatment, an increase in the hardness of the floor was observed owing to the precipitation of m23c6 during the transformation and the austenitic martensitic transformation during tempering. the secondary carbide m7c3 precipitated during heating up to 850 °c. at 980 °c, the transformation to m23c6 was complete. we also carried out heat treatment, but with completely different parameters. franco studied the abrasive and wear resistance of an alloy with 2.8% c and 14% cr [21]. the results revealed the presence of a high percentage of martensite/austenite at 930 °c–990 °c and secondary carbides, which provided high abrasion and wear resistance and indicated the absence of eutectic carbides. because the floor was hard and able to bear loads and reduce plastic deformation during impact with balls, heating to 1050 °c increased wear because the ground had low martensite/austenite content and secondary carbides. in the completed research, we used a wear device in accordance with a specification and a different programme in heat treatment. chabak demonstrated the role of tempering temperature in developing wear resistance in cast iron (5 wt.% w, 5 wt.% mo, 5 wt.% v, 10 wt.% cr, 2.5 wt.% ti, 0.3–1.1 wt. %c and 1.5–2.5 wt.% b) [22]]. heat treatment was carried out by heating hardening to 900 °c–1200 °c for 2 h, then cooling with oil and returning at 200 °c. the resulting microstructures showed the deposition of ferrite, martensite and pearlite/bainite in the floor with secondary carbide, which greatly reduced the corrosion rate. in [23], xiong studied the effect of instability time on the microstructure and properties of high-hypoeutectic cast iron. the hardness of carbides was determined to be related to proportion and size, and the hardness continued to increase with the increase in the size of dual carbides, reaching the maximum hardness at 950 °c–1000 °c. when kept at this temperature, the carbides melted in the ground, which reduced the hardness. therefore, the retention time should not be prolonged. our research tackled the effects of two different heat treatments on the microstructure, impact toughness and hardness of high-chromium white cast iron with different proportions of niobium and manganese. in this work, the structure of all samples contained mainly austenite and a small amount of micrometre-sized martensite near the carbides in the ali hatra al-khwarizmi engineering journal, vol. 21, no.1, pp. 7388 (2025) 86 ground. the width of the martensite increased in the ground, and the shape of the eutectic cementite and secondary carbide turned into round after heat treatment of the samples, which led to an increase in hardness and wear resistance. the carbides in the samples consisted of primary carbide m7c3, carbide m2c and eutectic cementite (fe, mn)3c in the ground. the ground structure was a mixture of austenite, pearlite and martensite. according to many studies, crystallisation takes place first from the molten state to m7c3 and molten and from the molten state to eutectic (austenite + m7c3/m23c6). a minimal amount of m2c carbide formed at a late stage of crystallisation, mainly due to the addition of manganese, which improved hardness and thus wear resistance. the addition of niobium and manganese controlled the formation of m2c and m6c carbides. at the crystallisation temperature of about 800 °c, a small amount of m23c6 carbide formed around the m7c3 carbide. precipitated carbide m2c, rich in nb and mn, also formed at the end of the crystallisation process. the chemical composition of the samples changed with the variation in niobium content. when the niobium percentage reached 1%, the ground structure was austenite and martensite. therefore, the ground of the high-chromium white cast iron was mainly composed of austenite, martensite and eutectic cementite secondary carbide m6c. through heat treatment, the impact toughness and wear resistance were increased, especially in the second case. by heat treatment 1, the shape of the eutectic cementite and secondary carbide was transformed into a circle. owing to hardening and reflux in treatment 2, the pearlite decreased, and the purity of the microstructure increased with the nb and mn addition. in sum, the addition of niobium and manganese controlled the formation of m2c and m6c carbides. implementing the gradual heat treatment programme 2 led to savings in economic costs and thus savings in heating time and temperature in heat treatment. 5. recommendations 1. heat treatments should be performed after adding nb and mn to improve mechanical properties such as impact durability and wear resistance. 2. heat treatment parameters and variables should be altered with comparison of the results. 3. other minerals should be added, if possible, and the resulting mechanical properties and microstructures should be assessed. 4. the shape of the breaking hammer or drill bit should be modified to enhance properties and lifespan, in addition to using simulation programmes to determine where the stresses are concentrated. references [1] guan yingfeng. (1999). study on the structure and properties of high chromium white cast iron and its tempering standard. [2] m.m. arikan, h. çimeno˘glu, e.s. kayal. (2001). the effect of titanium on the abrasion resistance of 15cr–3mo white cast iron. [3] xiaojun wu. (2007). effect of titanium on the morphology of primary m7c3 carbides in hypereutectic high chromium white iron. [4] s zic. (2009). bitmetallic hammer casting. [5] a studnicki, j kilarski, m przybyl, j suchon, d bartocha. (2012). wear resistance of chromium cast iron-research and application. [6] [i f. parente, f j belzunce and c r y j riba. (2013). mechanical strength and fracture toughness of high chromium white cast irons. [7] j o agunsoyer, v s aigbodion and o s sanni. (2014). effect of heat treatment on microstructure and mechanical properties of nf6357a cast alloy for wear resistance application. [8] m h ford. (2017). types of carbides formed in high chromium white cast iron during crystallization. [9] b hinckley 1, k f dolman. (2019). sem investigation of heat treated high chromium cast iron. [10] s lung. (2019). formed high chromium white cast iron and cast at different temperatures. [11] abaad k, walaa a. (2019). improving the maechanical properties and wear resistance of the high chromium white cast iron using heat treatment, al-baath university. [12] abaad k, albetar. (2020). the effect of titanium addition on mechanical properties and wear resistant of high chromium white cast iron, al-baath university. [13] m biere. (2020). the effect of silicon on high chromium white cast iron. [14] kh abdel aziz, adel a omar. (2020). micostructure modification of as cast high chromium white iron by heat treatment. ali hatra al-khwarizmi engineering journal, vol. 21, no.1, pp. 7388 (2025) 87 [15] hua nan liu, mikio nomurabm. (2020). abrasion resistance of high cr cast irons at elevated temperature. [16] luan nh, koizumi k, okuyama t. (2020). influence of nb and v addition on abrasive and impact wear properties of 16% cr–3% mo white cast iron. materials transactions. dec 1;61(12):2363-70. [17] guitar ma, nayak up, britz d, mücklich f. (2020). the effect of thermal processing and chemical composition on secondary carbide precipitation and hardness in high-chromium cast irons. international journal of metalcasting. jul;14:755-65 [18] luan nh, koizumi k, mizuno k, yamada y, okuyama t, nakayama m. (2022) role of matrix structure on impact-wear resistance of as-quenched 27% cr cast iron. materials transactions. may 1;63(5):740-7. [19] le nué c, corujeira gallo s, vahid a, wang j, taherishargh m, attar h, fabijanic d, barnett m. (2023). destabilization treatment and its influence on microstructure and matrix hardness of high-cr cast iron. metallurgical and materials transactions a. dec;54(12):4952-65. [20] ngo hk, yamamoto k, okuyama t, nakayama m, mizuno k, koizumi k. (2024). influence of heat treatment on erosive wear resistance of high cr cast irons. international journal of metalcasting. sep 24:1-4. [21] franco ar, sanchez caceres ja, rocha dl. (2024). study of the erosive-abrasive wear resistance of fe-14% cr-2.8% c high chromium cast iron. materials research. jan 8;27:e20230242. [22] chabak y, efremenko v, petryshynets i, golinskyi m, shimizu k, efremenko b, kudin v, azarkhov a. (2024). role of quenching temperature selection in the improvement of the abrasive (al2o3) wear resistance of hybrid multi-component cast irons. materials. jul 28;17(15):3742. [23] xiong l, liu y, zeng q, lai j, qiao x. (2024). effect of destability time on microstructure and properties of hypoeutectic high chromium cast iron. rsc advances.14(11):7459-67 (2025) 73-88، صفحة 1، العدد21مجلة الخوارزمي الهندسية المجلد هعلي هتر 88 تأثير المعالجة الحرارية على البنية المجهرية ومتانة الصدم وقساوة الحديد الصب األبيض عالي الكروم المضاف إليه معدني النيوبيوم والمنغنيز *3, نسيم الضاهر2, احمد سالمة1علي هتره سوريا ،جامعة تشرين، واإلنتاج في كلية الهندسة الميكانيكية والكهربائيةقسم هندسة التصميم 2،1 سوريا ،جامعة تشرين، قسم هندسة التصميم واإلنتاج في كلية الهندسة الميكانيكية والكهربائية 3 nassimaldaher111@gmail.comالبريد االلكتروني:* مستخلصال نسب مختلفة تم العمل على إضافة المنغنيز والنيوبيوم إلى الحديد الصب األبيض عالي الكروم الذي تصنع منه أدوات الحفر والطحن، وذلك وفق صهرتين ب الصب األبيض عالي الكروم من أهم ، حيث يعتبر الحديد %(1.1والنيوبيوم % 3.5، المنغنيز %0.49والنيوبيوم % 2.75المنغنيز )من المغننيز والنيوبيوم حيث يعمل النيوبيوم على زيادة مقاومة االهتراء. السبائك المستخدمة في التطبيقات الشاقة، وتتأثر خواصه بالعناصر السبائكية المضافة والمعالجة الحرارية الصدم، أما المنغنيز فيزيد من متانة. حسن االستجابة للمعالجة الحراريةوالقساوة، وله قدرة عالية جدًا على تشكيل الكربيدات، ويزيد من التوصيل الحراري مما ي درجة مئوية مع فترة 950التسخين إلى -1( )2)، (1)تم إجراء المعالجة الحرارية وفقًا لبرنامجين مختلفين . ويخلص الحديد من األكسجين، ويقلل من مرونته درجة 425دقيقة، ثم التبريد في الفرن والعودة إلى 20درجة مئوية مع فترة ابقاء لمدة 960التسخين إلى -2ابقاء لمدة ساعتين والتبريد في الهواء الجوي، . 2، 1والقساوة قبل وبعد المعالجة الحرارية وتمت مقارنة الخصائص الميكانيكية، مثل مقاومة االهتراء ومتانة الصدم.( ساعات 3مئوية لمدة mailto:nassimaldaher111@gmail.com <4d6963726f736f667420576f7264202d20cacdd3ede420e6dae1c7c120d4c8edc831332d203238> this is an open access article under the cc by license : al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 18, no. 2, june, (2022) p. p. 1328 path planning and obstacle avoidance of a mobile robot based on gwo algorithm tahseen fadhil abbas * alaa hassan shabeeb** *,**department of production engineering and metallurgy/ university of technology/ baghdad/ iraq *email: 70047@uotechnology.edu.iq **email: alaa.h.shabeeb@uotechnology.edu.iq )2022 march 27; accepted 2202 january 16received ( https://doi.org/10.22153/kej.2022.03.003 abstract planning is among the most significant in the field of robotics research. as it is linked to finding a safe and efficient route in a cluttered environment for wheeled mobile robots and is considered a significant prerequisite for any such mobile robot project to be a success. this paper proposes the optimal path planning of the wheeled mobile robot with collision avoidance by using an algorithm called grey wolf optimization (gwo) as a method for finding the shortest and safe. the research goals in this study for identify the best path while taking into account the effect of the number of obstacles and design parameters on performance for the algorithm to find the best path. the simulations are run in the matlab environment to test the performance of the proposed algorithm. simulations results showed that the proposed path planning algorithm effective performance by finding the shortest and free-collision path in different collide environments. furthermore, the superiority of the proposed algorithm was proved through comparisons with other famous path planning algorithms with different static environments. keywords: grey wolf optimization (gwo), mobile robot, path planning, obstacle avoidance. 1. introduction the fourth industrial revolution and digital innovation have led to the increased interest in the use of robots across industries; thus, robots are being used in various industrial sites, households, military, and medical [1]. in the field of robotics, two important issues are travel preparation (path planning) and collision avoidance, which are studied and discussed by numerous researchers in the past three decades. the primary reason for motion planning is to discover an optimal or almost optimal track from initial to final destination point with the potential for collision avoidance. therefore, route planning is an important aspect of designing a quick and efficient navigation procedure [2,3]. path planning can be considered a problem of optimization since it's aimed at finding a path with the shortest distance beneath certain restrictions such as the given environment with motion [4]. therefore, ensuring a safe route and good path is a difficult challenge for any wheeled mobile robot (wmr). so, attention to the pathplanning approach to enable a mobile robot to navigate from the starting point to the final destination with avoiding obstacles is a fundamental need. the major focus of the path planning challenge is on both efficiency and safety. wmr's most fundamental need from an engineering standpoint would be to arrive at its allocated destination safely. to achieve this, any collisions with obstacles must be avoided and prevented [5]. as a result, obstacle avoidance is a prerequisite in the path-planning issue. secondary criteria might be developed when obstacle avoidance was determined as the primary need. the length of the path should be considered. the goal of the pathplanning challenge is for wmr to move from its current location to its destination location with the tahseen fadhil abbas al-khwarizmi engineering journal, vol. 18, no. 2, p.p. 1328 (2022) 14 shortest path. this implies that the method will be more plausible if the path is shorter. furthermore, the shorter the path, the less time the robot will need to complete the journey [6]. the algorithm's efficiency is also a secondary criterion. in this scenario, the computational cost that the algorithm requires to complete its assigned job is referred to as algorithm efficiency. so, when considering obstacle collision and path length, the algorithm's processing cost must be considered. if an algorithm is computationally costly yet produces a path that isn't considerably better than the competition, it loses its competitive edge. a credible algorithm should balance between the amount of time it takes to run and the quality of the results it generates [7]. in the present work, grey wolf optimization (gwo) algorithm is presented, to solve path planning problems and obstacle avoidance in stationary environments. the goal of this study is to generate an optimal path that would lead to wmr moving in the safe paths, with the quickest time possible. 2. literature survey of previous research recently, researchers and scientists have developed a variety of nature-inspired algorithms. the common objective of these algorithms is to improve the quality of the solutions, stability, and performance of convergence to solve and enhance the path planning of wmr. ronald uriol and antonio moran. [8] presented ant colony optimization (aco) algorithm to solve the path planning challenge for mobile robots, by creating a graphical simulation interface to test and examine the algorithm's performance by looking at parameter settings such as (number of iterations and population) and robot operating environments (number of obstacles). according to the simulation results, a uniform increase in the number of obstacles is primarily overcome by a moderate increase in the ant population, to reduce simulation time and traveled path without collision with obstacles. harshal s. dewang et al. [9] (2018) proposed adaptive particle swarm optimization (apso) for getting a solution to the mobile robot path planning problem. the adaptive algorithm was tested by running different simulated experiments in several static environments. to evaluate apso, a comparison between classical pso and the proposed algorithm has been carried out based on two parameters: the running time of the algorithm and path length. the simulation results indicated that the apso was effective in the navigation process, with the shortest path and less computational time compared to classical pso. rakaa t. kamil, et al. [10] proposed a modified version of the artificial bee colony (abc) algorithm, namely adaptive dimension limit artificial bee colony (adl-abc) algorithm to find the best route with circular-shaped static obstacles in the static environment for a mobile robot. two tests (or cases) are applied in this work to make a comparison between abc and adlabc algorithms. the simulation results showed that the adl-abc was better than abc in finding a short path with a fewer number of iterations and less computational time. fatin h ajeil et al. [11] have proposed the hybridization of particle swarm optimization (pso) and modified frequency bat algorithm (mfb) for the planning of the optimal path with an obstacle avoidance strategy. the overall simulation results evaluated indicated the efficacy of the proposed pso-mfb algorithm in static and dynamic environments. a. mallikarjuna raoa et al. [12] proposed adapted grey wolf optimization (gwo) algorithm to robot path planning problems. the robot path planning was implemented in an environment containing three circular shapes. the simulations of the path planning were achieved by finding three points between start, target point. during each iteration, these three points are updated by the gwo algorithm. if the solution point is in the obstacle zone, then the violation is added to the cost function. the results comparison show that the optimal path is found best results for the user test environment. muna mohammed jawad, and esraa adnan hadi [13] have proposed the hybrid (ffcpso) algorithm to the optimal path for mobile robots by combining the advantages of chaotic pso (cpso), and firefly (ff) to solve the global path-planning problem for the single and multirobot environment. the simulation results are carried out in a matlab environment. the overall evaluated results indicated that the ffcpso is a better choice than individuals’ algorithms (pso, ff). try researchers and scientists have developed several of the strategies for improved path planning of the mobile robot. the strategy proposed in this research for improved finding the best and safe next position for a mobile robot depended on the gwo algorithm with study the effects of the design parameters on performance for the algorithm to reduce the total time for the pathfinding in various environments. tahseen fadhil abbas al-khwarizmi engineering journal, vol. 18, no. 2, p.p. 1328 (2022) 15 3. environment model and obstacle extended the wmr environment in this research work contains many static obstacles, after detection and processing, all obstacles are surrounded and regulated by circle shape to reduce the computation complexity and same time improve the measurement accuracy of the system. in this process, to ensure wmr safety when attempting mobility in the environment, the obstacle size will be increased by adding a safety distance value, as shown in figure 1. after creating a 2d map with a start, destination point, and obstacles, it's used to construct wmr movement. wmr is represented in this map as a point by a collection of cartesian coordinate positions (x,y). fig. 1. increase the size of the obstacles. 4. fitness function and selection the goal of the path planning issue is to discover the best route between a beginning point and a target point. the best road to take may be the one that is the shortest takes the least amount of time and uses the least amount of energy. in most path planning issues, the shortest path is considered the goal function. the x-y coordinates of the mobile robot change once it moves from one spot to the next. in this study, the objective function value for each particle/ agent used is given in eq. (1) ���� = ⎩⎪ ⎨ ⎪⎧ ��� � − � � + � �� + ���� − ��� + ��� �for feasible paths� ��� � − � � + � �� + ���� − ��� + ��� + !"#$%& �for infeasible paths� …(1) where; f (i) is the fitness function of the summation distance between path points, � � and ��� is robot’s current position, � � + � and ��� + � is the robot’s next position. 5. grey wolf optimization (gwo) the gwo method, proposed by mirjalili et al. [14], is a newcomer in the field of nature-inspired optimization algorithms. grey wolves' hunting tactics and social order are used to create the grey wolf optimizer (gwo). grey wolves are divided into four groups: alpha, beta, delta, and omega wolves, according to the hierarchy. the alpha wolf is the group's leader or dominant wolf, and alpha wolves follow the other wolves in the pack. the alpha is the best wolf in terms of managing the group. beta wolf is the second in the wolf group's social structure. beta assists the alpha wolf in a variety of duties. the delta wolf must subordinate to the alpha and beta wolves, but the omega wolves are judged by the delta wolf [14]. grey wolves' collective hunting method is another fascinating social characteristic. the grey wolves use the approach to first detect the location of prey (solution) and then encircle it under the guide of the alpha wolf. in a mathematical model of grey wolf hunting strategy, the alpha, beta, and delta wolves are assumed to have a greater understanding of probable prey locations. as a consequence, the gwo algorithm updates the locations of wolves using the first three best solutions (alpha, beta, and delta), figure.2, showing a flowchart of the gwo algorithm. in the gwo code, there are no omega wolves. tahseen fadhil abbas al-khwarizmi engineering journal, vol. 18, no. 2, p.p. 1328 (2022) 16 fig. 2. flowchart of path planning based on gwo algorithm [15]. the following is a mathematical model of the grey wolf hunting mechanism [15]: ())⃗ + = ,-)⃗ +. /))⃗ + − /))⃗ 0, ; ())⃗ 2 = ,-)⃗ 2 . /))⃗ 2 − /))⃗ 0, ; ())⃗ 3 = ,-⃗3 . /⃗3 − /⃗4, …(2) 5)⃗ + = ,/))⃗ + − 6))⃗ +. ())⃗ +, ; 5)⃗ 2 = ,/))⃗ 2 − 6))⃗ 2 . ())⃗ 2, ; 5)⃗ 7 = ,/))⃗ 7 − 6))⃗ 7. ())⃗ 7, …(3) /⃗�89:� = ;)⃗<9 ;)⃗ =9 ;)⃗ >? …(4) ())⃗ @ , ())⃗ a, and ())⃗ 3 are the distance vectors between the prey and the wolf (alpha, beta, delta), /⃗@ , /⃗a, and /⃗3 represent the location vector of the prey for alpha, beta, and delta wolves. /⃗ represents the grey wolf's location vector at t+1 iteration, the coefficient vectors of alpha, beta, and delta wolves are denoted by -⃗@ , -⃗a, -⃗3 , 6⃗@, 6⃗a and 6⃗3 respectively. the trial vector for an alpha, beta, and delta wolves is denoted by the letters 5)⃗@, 5)⃗ a, and 5)⃗ 3 . for alpha, beta, and delta wolves, the coefficient vectors are determined as follows: 6))⃗ b = 2d)⃗ . e⃗1 − d)⃗ …(5) -)⃗ b = 2. e⃗2 …(6) where i is +, 2, and 7. a denotes a linear reduction in the vector from 2 to 0 during optimization, the initial random vector in [0,1] is denoted as r. members of the grey wolf pack change their locations based on alpha, beta, delta, and delta wolves, as well as prey. the grey wolves catch their victim and then attack it to conclude the hunt. it=it+1 update the a, c, a initialize the parameters of gwo (a,c,a) initialize the grey wolf population n with random position calculate the fitness value for each search agent update the position for search agents from 1:n determine the current first three best wolf’s optimum in the pack and update the /⃗@, /⃗a , and /⃗3. stopping criteria satisfied output result end yes no it=1 determine the position for each agent initialize the environment with obstacles, identify the start and target point start tahseen fadhil abbas al-khwarizmi engineering journal, vol. 18, no. 2, p.p. 1328 (2022) 17 this situation is defined as a decreasing vector in the mathematical model given below: d)⃗ = 2 − g 2∗b0ie b0iejdkl …(7) 6. simulation result 6.1. environment setup three environments are selected to validate the proposed approach. in all cases, the map dimensions are (2400 x 2200) mm, number of handle points is equal to 3 (via points). these environments have static obstacles located at random positions and are unknown in the workspace environment. there is no prior information of the initial wmr location, obstacles, and target location, and assume wmr environment information is defined based on assuming using an external sensor (overhead camera), to build the environment simulation as input to simulated and path find based on a proposed intelligent algorithm. matlab r2019b programming language used to create the simulation code for path planning using tested on intel(r) core i7, 2.2 ghz cpu, 8.00 gb ram system. in the mass point simulation, wmr is considered a dimensionless point. table 1 shows the parameter settings of algorithm parameters that have been used in the simulation. table 1, parameters used for the gwo algorithm. parameter value wolf sizes (population) 100 no of iterations 10, 20, 40, 80 6.2. simulation analysis and discussion to determine the effectiveness and efficiency of the proposed algorithm presented in this research work to find the optimal path to wmr navigation, the algorithm was tested in three cases studies (different collide environments). in each environment the optimal path after 100 iterations was selected depending on the safe path as the first step, and the path distance between the start point to the target point, which is determined depending on eq. 1. case 1: the environment for case study one contains five obstacles as shown in figure (4). the start point of wmr (red circle) and the target point (blue circle) are placed at (165.50, 321.99) mm, and (1797.09, 1773.72) mm respectively as shown in figure 3. fig. 3. the environment of case 1. the simulation result of the optimum route for the first case based on the proposed algorithm is shown in figure 4. while figure 5. plotted the relation of the length of the optimal path (better fitness) and the number of iterations for estimation of the optimal value of the objective function for target point start point tahseen fadhil abbas al-khwarizmi engineering journal, vol. 18, no. 2, p.p. 1328 (2022) 18 the presented algorithm. in the simulation results of case one, the optimal path of the gwo is equal to 2252.24 mm with a computation time of 9.03 sec. which achieved the optimal solution (better fitness). fig. 4. path found by gwo algorithm for case 1 fig. 5. best distance function founded by gwo for case 1. case 2: in this case study, the environment contains eight obstacles as shown in figure (4). the start point of wmr (red circle) and the target point (blue circle) are placed at (168.46, 322.19) mm, and (2039.59, 1766.56) mm respectively as shown in figure 6. tahseen fadhil abbas al-khwarizmi engineering journal, vol. 18, no. 2, p.p. 1328 (2022) 19 fig. 6. the environment of case 2. the simulation result of the optimum route for the second case based on the proposed algorithm is shown in figure 7. while figure 8. plotted the relation of the length of the optimal path (better fitness) and the number of iterations for estimation of the optimal value of the objective function for the presented algorithm. in the simulation results of case two, the optimal path of the gwo is 2493.03 mm with a computation time of 10.59 sec. which achieved the optimal solution (better fitness). fig. 7. path found by gwo algorithm for case 2. target point start point tahseen fadhil abbas al-khwarizmi engineering journal, vol. 18, no. 2, p.p. 1328 (2022) 20 fig. 8. best distance function founded by gwo algorithm for case 2. case 3: in case three the environment contains twelve obstacles as shown in figure (4). the start point of wmr (red circle) and the target point (blue circle) are placed at (207.15, 318.23) mm, and (2048.32, 914.44) mm respectively as shown in figure 9. fig. 9. the environment of case 3. the simulation result of the optimum route for the third case based on the proposed algorithm is shown in figure 10. while figuring 11, plotted the relation of the length of the optimal path (better fitness) and the number of iterations for estimation of the optimal value of the objective function for the presented algorithm. in the simulation results of case three, the optimal path of the gwo is 2493.03 mm with a computation time of 11.77 sec. which achieved the optimal solution (better fitness). start point target point tahseen fadhil abbas al-khwarizmi engineering journal, vol. 18, no. 2, p.p. 1328 (2022) 21 fig. 10. path found by gwo algorithm for case 3. fig. 11. best distance function founded by gwo algorithm for case 3. 6.2.1 evaluation of design parameters effects on gwo algorithm performance the evaluation is made by summarizing the results for gwo of the three cases environments after executing the algorithm 10 times with four ranges of the number of iterations (10, 20, 40, 80) to evaluate the performance results of the proposed algorithm, on the length of the path and reducing simulation time. each environment has four paths of safe paths as the first step and distances of these four paths between start point to target point are determined depending on eq. 1. the best path length is the optimal path between the four best paths achieved by the algorithm in this work. the black path is the best path between the four optimal paths achieved by the algorithm. the best path was selected depending on concerning the safety of the path, path length. the performance comparison of the presented algorithm was measured based on the path length, the simulation time. case study one: the simulation results of case one, for the gwo algorithm, with four ranges of the number of iterations as shown in figure 12. in the first path with 10 iterations, the optimal path is equal to 2264.36 mm with a computation time of 8.44 sec. the optimal path of the second path with 20 iterations is equal to 2259.79 mm with a computation time of 8.55 sec. the optimal path of the third path with 40 iterations is equal to 2256.82 mm with a computation time of 8.96 sec. for the fourth path with 80 iterations, the optimal path of the gwo is equal to 2252.24 mm with a tahseen fadhil abbas al-khwarizmi engineering journal, vol. 18, no. 2, p.p. 1328 (2022) 22 computation time of 9.03 sec, which achieved the optimal solution (better fitness). case study two: in case two as shown in figure 14, the simulation results of the gwo algorithm with a first range of the number of iterations, the optimal path is equal to 2685.25 mm with a computation time of 8.48 sec. the shortest path of the second range of iterations is equal to 2513.48 mm with a computation time of 9.10 sec. the optimal path of the third of iterations is equal to 2495.37 mm with a computation time of 9.89 sec. for the fourth path with the fourth range of iterations, the best path of the gwo is equal to 2493.03 mm with a computation time of 10.59 sec, which achieved the optimal solution (better fitness). case study three: the simulation results of case three as shown in figure 16, for the gwo algorithm, for the first path with 10 iterations, the optimal path is equal to 2452.54 mm with a computation time of 8.44 sec. the optimal path of the second range of iterations is equal to 2438.49 mm with a computation time of 9.12 sec. the optimal path of the third path with 40 iterations is equal to 2433.38 mm with a computation time of 10.57 sec. for the fourth path with the fourth range of iterations, the optimal path of the gwo is equal to 2430.19 mm with a computation time of 11.77 sec, which achieved the optimal solution (better fitness). the performance results of the proposed gwo algorithm are summarized in table 2. the performance comparison of the gwo was showed a relationship between the number of obstacles and the number of iterations to find a safe and shortest path with reduce simulation time. results indicated that a uniform increase of obstacles is mostly solved by a moderate increase in the number of iterations to ensure reduced simulation time without collision with obstacles as shown in figures 13, 15, and 17. fig. 12. path found by gwo algorithm for case 1. fig. 13.the execution time of the gwo algorithm for case 1. tahseen fadhil abbas al-khwarizmi engineering journal, vol. 18, no. 2, p.p. 1328 (2022) 23 fig. 14. path found by gwo algorithm for case 2. fig. 15. the execution time of the gwo algorithm for case 2. fig. 17. the execution time of the gwo algorithm for case 3 tahseen fadhil abbas al-khwarizmi engineering journal, vol. 18, no. 2, p.p. 1328 (2022) 24 fig. 16. path found by gwo algorithm for case 3. table 2, comparison of the shortest path length and the time of execution of the gwo algorithm. 6.3 evaluation of the gwo executing the simulation process of any algorithm technique in different environments is not sufficient to assert that it is best. it should provide some proof compared with previously applied strategies to sure that the proposed technique is better. from this point, the proposed algorithm was compared with other algorithms for the same tested cases to determine the response in the selected environment. the environment has been generated as stated by other authors, and the gwo algorithm has been applied to similar environments, to demonstrate the efficiency of the proposed algorithm. 1in the first comparative study, which has been carried out by reference [16]. the simulation results were obtained using cfa-oas and adaptive firefly algorithm (afa), the navigation system is demonstrated in figure (18, (a)). while the result obtained using the proposed algorithm is presented in figure (18, (b)). table 3. summarizes the best path length, which can be achieved between the proposed gwo algorithm and the algorithms of reference [16]. environment number obstacles iterations number optimal path length (in cm) gwo execution time (in seconds) case 1 5 10 2264.36 8.44 20 2259.79 8.55 40 2256. 82 8.96 80 2252.24 9.03 case 2 8 10 2685.26 8.48 20 2513. 48 9.10 40 2495.37 9.89 80 2493.03 10.59 case 3 12 10 2452.54 8.44 20 2438.49 9.12 40 2433.38 10.57 80 2430.19 11.77 tahseen fadhil abbas al-khwarizmi engineering journal, vol. 18, no. 2, p.p. 1328 (2022) 25 fig. (18, (a)-(b)). the best results achieved by (a) reference [16], and (b) gwo. table 3 , results comparison with reference [16]. figure no. method navigation path length (cm) fig (10, (a)). afa [48] 12.41 fig (10, (a)). cfa-oas [48] 11.85 fig (10, (b)). gwo 11.83 2the second comparison investigation, based on reference [17], was carried out. they have developed their path planning algorithm based on the approach namely, the adaptive tumble bacterial foraging optimization (at-bfo). figure (19, (a)) shows the simulation results obtained from the stated at-bfo algorithm. while, the result obtained from using the proposed algorithm is illustrated in figure (19, (b)). table 4. summarizes the best path length, which can be achieved between the proposed gwo algorithm and the algorithms of reference [17]. fig. (19, (a)-(b)). the best results achieved by (a) reference [17], and (b) gwo. (a) (b) y -a x is (a) (b) x-axis tahseen fadhil abbas al-khwarizmi engineering journal, vol. 18, no. 2, p.p. 1328 (2022) 26 table 4 , results comparison with reference [17]. figure no. method navigation path length (m) fig (19, (a)). at-bfo [17] 14.5346 fig (19, (b)). gwo 14.3574 from the results obtained, it can be noticed that the proposed algorithm (gwo) provides the shortest path from start to goal position as compared to results obtained by references, [16], and [17]. 7. conclusion in this paper, we suggested path planning and obstacle avoidance based on the grey wolf optimization path algorithm for wmr in environments with static obstacles. through analysis of the performance of the algorithm in wmr working environments with studying the effects of the design parameters of the algorithm such as (the number of iterations and number of population) in reducing simulation time and length of the path in different collide environments the main conclusions of this research can be drawn as follows: 1. the proposed algorithm is proved efficient in finding an optimal path without collision with obstacles. 2. the effect of the values selected of design parameters of the proposed algorithm in reducing simulation time and length of the path without collision with obstacles. 3. the directional relationship between the number of obstacles and the number of iterations. the uniform increase of obstacles is mostly solved by a moderate increase in the number of iterations 4. the proposed algorithm proved the superiority compared with algorithms applied by other researchers, in simulation mode, the results proved that the proposed algorithm is effective in generating the optimal and shortest path, which is positively reflected in the promising applications of this proposed algorithm. the future work will test the proposed algorithm in real-time wmr navigation. 8. references [1] t. f. abaas, and a. h. shabeeb. "autonomous mobile robot navigation based on pso algorithm with inertia weight variants for optimal path planning." iop conference series: materials science and engineering. vol. 928. no. 2. iop publishing, 2020. [2] a. s. al-araji, a. k. ahmed, and m. k. hamzah. "development of a path planning algorithms and controller design for mobile robot." 2018 third scientific conference of electrical engineering (scee). ieee, 2018. [3] a. s. al-araji, and n. q. yousif. "a cognitive hybrid tuning control algorithm design for nonlinear path-tracking controller for wheeled mobile robot." alkhwarizmi engineering journal 13, no. 3 :6473, 2017. [4] b. b. kwame, r. chellali, a. y. appiah, and f. kyeremeh. "an overview of natureinspired, conventional, and hybrid methods of autonomous vehicle path planning." journal of advanced transportation, 2018. [5] i. k. ibraheem, and f. h. ajeil. "path planning of an autonomous mobile robot using swarm based optimization techniques." alkhwarizmi engineering journal 12, no. 4 (2016): 12-25. [6] h. kong, j. sun, and j. hu. "real-time motion planning based on layered cost map for agv navigation." in 2020 chinese automation congress (cac), pp. 7624-7628. ieee, 2020. [7] c. b. lamini, s. and, a. elbekri. " genetic algorithm based approach for autonomous mobile robot path planning". procedia computer science, 127, pp.180-184, 2018 [8] r. uriol, and a. moran. "mobile robot path planning in complex environments using ant colony optimization algorithm." in 2017 3rd international conference on control, automation and robotics (iccar), pp. 15-21. ieee, 2017. [9] h. s. dewang, p. k. mohanty, and s. kundu. 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"a comparative study for wheeled mobile robot path planning based on modified intelligent algorithms." the iraqi journal for mechanical and materials engineering 19, no. 1 : 60-74, 2019. [14] s. nadimi, m. h., s.taghian, and s. mirjalili. "an improved grey wolf optimizer for solving engineering problems." expert systems with applications vol 166: 113917, 2021. [15] t. f. abaas, and a. h. shabeeb. "safe and optimum navigation of wheeled mobile robot using grey wolf optimization algorithm." iop conference series: materials science and engineering. vol. 928. no. 2. iop publishing, 2020. [16] d. pang, g. guan, and j. li. "chaotic firefly algorithm with the optimization adjustment strategy for mobile robot path planning." international journal of science 4, no. 3 (2017). [17] n.h. abbas and ali, f.m., path planning of an autonomous mobile robot using enhanced bacterial foraging optimization algorithm. alkhwarizmi engineering journal, 12(4), pp.2635, 2016. ) 2022( 1328، صفحة 2العدد، 18مجلة الخوارزمي الهندسية المجلد تحسين فاضل عباس 28 gwo تخطيط المسار وتجنب العوائق لروبوت متنقل على أساس خوارزمية **عالء حسن شبيب *تحسين فاضل عباس العراق /بغداد /الجامعة التكنولوجية / قسم هندسة اإلنتاج والمعادن *،** uotechnology.edu.iq@70047بريد إلكتروني: * alaa.h.shabeeb@uotechnology.edu.iqبريد إلكتروني: ** الخالصة بإيجاد طريق آمن وفعال في بيئة مزدحمة نظًرا ألنه مرتبط ،تعد مشكلة تخطيط المسار من بين المشكالت األكثر أهمية في مجال أبحاث الروبوتات متنقل. تقترح هذه الورقة التخطيط األسرع واألمثل لمسار الروبوت للروبوتات المتنقلة ذات العجالت، ويعتبر شرطًا أساسيًا مهًما لنجاح أي مشروع روبوت .كطريقة للعثور على أقصر الطرق وأكثرها أماًنا (gwo) المتحرك ذي العجالت مع تجنب االصطدام باستخدام خوارزمية تسمى تحسين الذئب الرمادي . تأثير عدد المعوقات ومعلمات التصميم على أداء الخوارزمية إليجاد المسار األفضل تهدف أهداف البحث في هذه الدراسة إلى تحديد المسار األفضل مع مراعاة عمليات المحاكاة أن خوارزمية تخطيط المسار المقترحة نتائج أظهرت .لتقييم كفاءة الخوارزمية المقترحة matlab عمليات المحاكاة في بيئة تنفيذ يتم عالوة على ذلك، تم إثبات تفوق الخوارزمية مختلفة. تحتوي على عوائق بيئات في من خالل إيجاد أقصر مسار وخالي من االصطدامات فعال تؤدي أداء .المقترحة من خالل مقارنات مع خوارزميات تخطيط المسار الشهيرة األخرى مع بيئات ثابتة مختلفة this is an open access article under the cc by license al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 19, no. 3, september, (2023) p. p. 7287 a study on the effect of multistage toolpath in fabricating a customized cranial implant in incremental sheet metal forming mohamed i. fahad* ahmed z. m. shammari** ramdziah binti md nasir*** *,**department of automated manufacturing engineering/ al-khwarizmi college of engineering/ university of baghdad/ baghdad/ iraq ***school of mechanical engineering/ engineering campus / universiti sains malaysia (usm) /14300 nibong tebal/ pulau pinang / malaysia corresponding author: *email: mohamed.ibra996@gmail.com **email: drahmed@kecbu.uobaghdad.edu.iq ***email: ramdziah@usm.my (received 8 november 2022; accepted 22 march 2023) https://doi.org/10.22153/kej.2023.03.003 abstract incremental sheet forming (isf) process offers a high degree of flexibility in the manufacturing of different sheet parts, which makes it an ideal candidate for prototype parts as well as efficient at fabricating various customized products at low production costs compared to traditionally used processes. however, parts produced in this process exhibit notable geometrical inaccuracy and considerable thickness reduction. in this paper, the single point incremental sheet forming variant of the process has been implemented to manufacture a highly customized cranial implant starting from the computed tomography (ct) scan data of the patient's anatomy. a methodology, from the modeling to the realization of the implant, is presented and discussed. the primary aim of the research was to analyze and study the effect of the multistage toolpath strategy compared to the traditional single-stage toolpath in terms of geometrical accuracy and thickness distribution. the final results show that the part formed in the multistage toolpath strategy exhibited a more uniform thickness distribution compared to the single-stage approach. regarding the geometrical accuracy, the deviation analysis between the nominal and actual data has revealed that the multistage forming has significantly enhanced the final geometrical accuracy of the formed part. keywords: incremental sheet forming, multistage, medical implant, thickness, geometrical accuracy. 1. introduction incremental sheet forming is an innovative forming process that was originally developed to overcome the limitations of conventional forming processes in terms of flexibility [1,2]. in this process, a hemispherical tool, typically mounted to cnc, moves progressively according to a predefined path using cad-cam technology. the forming tool engages with the clamped sheet at small contact areas, imposing localized plastic deformation that enhances the process's formability compared to traditional stampings. characterized by its high flexibility, the process can accommodate different design specifications, including symmetrical and asymmetrical geometries, without changing the process setup. in addition, the process does not require dedicated dies, complex tooling, or fixtures. as a result, it dramatically reduces production costs. these features made the process efficient for prototyping and small-batch production in the automotive and mailto:mohamed.ibra996@gmail.com mailto:email:%20ramdziah@usm.my mailto:email:%20ramdziah@usm.my https://doi.org/10.22153/kej.2023.03.001 mohamed i. fahad al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 7287 (2023) 73 aerospace industry. however, the process suffers from notable drawbacks: reduced geometrical accuracy, non-uniform thickness distribution, and formability constraints in some materials when producing certain features. the idea of optimizing the isf process has been studied by many researchers since it first emerged by investigating different process parameters, and as a result, there is well-established literature that provides a guideline to improve the process outcome to some extent [3]. in the last two decades, the biomedical field has exploited the flexibility and advancement of the process, in which it has been extensively implemented and researched to produce highly customized implants and devices at reduced time and cost compared to traditional methods. this includes the manufacturing of a cranial implant [4,5,6], an ankle support [7], a knee-bearing device [8], a denture base [9], a clavicle bone implant [10], and a craniofacial implant [11]. the multistage tool path strategy was developed to enhance the formability of the process by redistributing the material across the geometry from shallow to sloped areas. this allows for the production of steep features that exceed the formability limit of the material as well as the formation of vertical walls that could not be obtained otherwise using the single-step strategy. for instance, duflou et al. [12] have experimentally implemented the multistage approach to form a cylindrical cup utilizing five forming stages. furthermore, the author also implemented the strategy to fabricate distinctive designs, including a high wall angle cranial implant. similarly, the gradual forming toward the final geometry using preforms has also been effective in duflou et al. [13] work, in which the authors have tested the approach to form complex craniofacial implants using different materials (stainless steel 304 and titanium grade 2). the implant geometry features a high wall angle that exceeds the forming limit of the titanium and makes it critical in the case of stainless steel. the strategy has doubled the forming depth in the titanium sheet, but the implant cracked due to the large gap between the maximum achievable wall of the titanium and the walls of the geometry. on the other hand, the multi-step strategy successfully formed the steel sheet into the final desired shape. liu et al. [14] describe the validity of the multi-pass tool path strategy compared to the single-pass forming. the work considered symmetrical and asymmetrical geometry. both of these shapes are produced experimentally using the two point incremental sheet metal forming process variant. the work provided a general understanding of the multistage toolpath and its effect on the thickness distribution and formability. in the case of the ellipsoidal cup shape, the part was successfully formed using the multistage strategy, whereas it experienced fracture in the single-pass forming. additionally, the multistage toolpath has optimized the final result in the case of the free-form shape in terms of thickness strain distribution and formability. mainly, most of the previous studies have implemented the multistage strategy to improve formability, and there is a general lack of research on the influence of the multistage on the final results in terms of geometrical accuracy and thickness distribution. gonzalez et al. [15] have reported on the influence of the multistage toolpath in incremental sheet forming on the final results by comparing it with the traditional single-stage forming. the study considers two main strategies to develop the multistage toolpath. the results have demonstrated that the multistage toolpath strategy has improved the final geometrical accuracy. however, the part produced by the multistage technique showed less uniform thickness distribution than the single-stage forming. likewise, gajjar et al. [16] have conducted experimental work investigating the effect of using a different number of forming stages in fabricating truncated cones. the obtained results show that increasing the number of intermediate steps has reduced the spring-back phenomena and, as a result, improved the geometrical accuracy of the produced part. in this paper, a case study is adopted that concerns the manufacturing of a highly customized cranial implant from the design stage to the realization of the prosthesis through the single-point incremental sheet forming process. the primary objective of the study is to examine and analyze the impact of the multistage toolpath strategy compared to the traditional single-stage forming in terms of the final geometrical accuracy and thickness variation of the formed part. 2. methodology the methodology utilized to obtain the customized cranial implant consists of several phases, starting from the ct scan image processing to the fabrication and inspection of the produced parts. the process depends on reverse engineering (re) and cad-cam technologies in data acquisition, modeling, and manufacturing. each phase encompasses different challenges and is discussed in detail, see fig. 1. mohamed i. fahad al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 7287 (2023) 74 fig. 1. the methodology used for obtaining the cranial implant. 2.1 image processing the process of constructing a customized cranial implant is usually initiated by acquiring the computed tomography (ct) scan data of the patient's anatomy. these data consist of sliced images that were reconstructed from the coronal plane and stored in a dicom (digital imaging and communications in medicine) file format. this phase aims to convert the ct data into a 3d model of the defective skull. in order to select the region of interest (roi) from these images, a process of image segmentation is carried out. in this crucial process, the cranium structure can be partitioned from the other entities using different techniques. the most commonly used, however, is global thresholding, which has been employed in this particular case using 3d slicer software (2021). the process maps out the desired roi based on a given range of hounsfield unit (hu) values. the values used for this specific segmentation range between 210-3070hu, which were the optimum values to highlight the bone voxels (fig. 2). subsequently, the 3d model of the skull was visualized and exported in stl file format. the 3d model of the skull obtained in this procedure required further post-processing, which includes triangulation and noise reduction. fig. 3 shows the final constructed skull. fig. 2. image processing of the ct scan data in 3d slicer software. image segmentation mohamed i. fahad al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 7287 (2023) 75 fig. 3. the constructed 3d model of the skull. 2.2 prosthesis design different approaches can be used to construct the cranial implant. each has its benefits and drawbacks [17]. in this study, since the defect lies beyond the centerline of the axial plane, the mirrorbased method has been implemented. in this technique, the symmetry of the skull has been exploited, as reference data, to design the prosthesis. the prosthesis was established using materialise 3 matic software. the steps involved in the design are illustrated in fig. 4 and are described below: 1. the first step in designing a patient-specific implant is to outline the defective area using a closed curve. the curve has been attached with an offset from the gap boundaries. 2. constructing a mid-plane that cuts through the skull centerline, separating the two halves. 3. mirroring the healthy side of the skull onto the defective side using the constructed plane as the mirroring tool. 4. the plane that intersects perpendicularly through the transverse plane has been established. later, this plane is utilized to create a reference sketch. 5. a spline has been sketched along the profile of the mirrored side and between the intersection points. 6. finally, the implant surface is constructed using the closed curve as the surrounding entity and the spline as the guideline for the final prosthesis profile. it should be noted that the constructed cranial prosthesis has not been given a uniform thickness, nor a variable thickness was defined since the final thickness of the part produced by the isf process cannot be predicted. therefore, the process requires only the modeling of the inner surface of the desired cad geometry [18]. fig. 4. steps involved in designing the cranial prosthesis. mohamed i. fahad al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 7287 (2023) 76 2.3 geometry preparing 2.3.1 geometry positioning complex, organically shaped geometries, such as medical implants and devices, contain curved features distributed asymmetrically along the part and at the edge. consequently, these geometries cannot be feasibly formed from a flat sheet in the spif process. thus, in order to prepare the model for cam processing, the desired implant must conform to the process constraints. this can be done by attaching the geometry to an auxiliary surface that properly connects the prosthesis geometry to the planar sheet. the virtual flat sheet is considered the reference xy plane at which the tool engages to form the defined geometry outward along the z-axis. the construction of an extended surface can also be advantageous in effectively reducing the maximum wall angle of the geometry by allowing flexible orientation of the part as well as supporting the implant during the forming process [19]. the prosthesis has been embedded within the surrounding surface using lofting within fusion 360 (fig. 5). fig. 5. the attachment of the cranial implant to the flat sheet with an auxiliary surface. 2.3.2 geometry analysis the analysis includes identifying the maximum wall angle of the geometry, which is an essential value that can be used to evaluate the feasibility of the process of forming this particular shape by comparing it to the maximum wall angle achievable by the material in the next section. the analysis involves taking a cross-section of the surface model. one is in the x-z section where y equals zero, and the other is in the y-z section where x equals zero, see fig. 6. fig. 6. section analysis of the final geometry. 2.4 material characterization the material used in the experimental work is a stainless steel aisi 304 sheet of 0.5mm in thickness. table 1 shows the material’s chemical composition. in this phase, the formability of the material has been analyzed and evaluated in terms of tensile and benchmark tests. these tests aim to establish and define the material limit and behavior prior to the forming process. thus, predictions can be made about whether or not the design can fail during manufacturing. in this context, the analysis functions as an input to address the challenges before carrying out the process. mohamed i. fahad al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 7287 (2023) 77 table 1, chemical composition of stainless steel aisi 304 2.4.1 tensile test the tensile test was carried out in a universal tensile machine. to examine the material anisotropy, three samples were cut out from the steel sheet at different orientations (0, 45, and 90) with respect to rolling direction, see fig. 7. material ductility was the main characteristic to investigate. in the isf process, the material is plastically deformed. therefore, the material elongation during a tensile test gives a viable indicator of sheet formability. the stainless-steel elongation averages 55.83% in all directions, which is considered relatively high in formability. this is expected to be further enhanced during the isf due to localized deformation. the material's mechanical properties are listed in table 2 fig. 7. tensile test specimens at different orientations with respect to rolling direction. table 2, mechanical properties of stainless steel 304 at different orientations. 2.4.2 benchmark test the failure mechanism in the incremental sheet forming process, when using standard-sized tools (between 6 to12 mm), is initiated by the onset of fracture. during the forming process and due to localized plastic deformation at small contact zones, the sheet experiences uniform thinning with the absence of necking till fracture takes place [20]. in this context, the maximum wall angle, i.e., the rupture angle, is considered the formability limit of the material. an efficient way to evaluate and define this limit is through a benchmark test using a truncated cone with a variable wall angle [21]. the design of the cone used in this test is illustrated in fig. 9. in this test, the steel sheet was formed until a fracture occurred (fig.8), and the cnc machine was immediately stopped. subsequently, the depth of the fracture was measured using a depth gauge, and as a result, the corresponding wall angle was obtained. from this test, it has been deduced that the maximum wall angle amissible by the steel sheet is 65.7, which is larger than the maximum wall angle of the desired geometry. thus, failure is unlikely when forming in a single pass since the design lies within the forming zone of the material. e lem en ts c mn si s p cr ni mo nb cu ti v f c o m p o sitio n (% w t.) 0.0483 1.03 0.606 0.0005 0.001 18 8.49 0.0474 0.0122 0.403 0.0002 0.095 balanced orientation yield strength (mpa) ultimate strength (mpa) elongation (%) rolling (0°) 285 620.78 58.75 diagonal (45°) 275 651 55 transverse (90°) 300 677.38 53.75 r o lli n g d ir ec ti o n mohamed i. fahad al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 7287 (2023) 78 fig. 8. the fractured truncated cone sample fig. 9. truncated cone used for formability test. 2.5 toolpath generation the movement of the forming tool across the sheet metal in order to fabricate the desired geometry is considered the most crucial aspect of the isf process, considering that it directly and significantly affects the final geometrical accuracy, thickness distribution, and surface roughness of the produced part. milling cam software packages are usually utilized to define and generate the toolpath in the isf process since there is no dedicated cam software for that purpose. in this work, a contour toolpath, a strategy that is mainly used for finishing, was generated using fusion 360. in this strategy, the tool starts from a reference xy plane and moves to the next successive plane contour by following a downward motion along the z-axis. by reducing the step-down value, i.e., the distance between two consecutive profiles, the surface roughness of the final formed part is dramatically reduced [6]. in single-stage forming, the toolpath is defined directly on the final desired geometry, whereas in multistage strategy, intermediate shapes, also known as pre-forms, are used. for each form or shape, a toolpath is generated (fig. 11). in other words, each stage essentially functions as a single-stage strategy. thus, rather than forming the part directly, the sheet will be formed gradually at each stage before reaching the desired geometry. as a result of this flow, the strategy enhances the process's formability. unlike the techniques used to develop pre-forms for symmetrical parts in which various well-established multistage strategies can be utilized and implemented, there is no standardized approach for developing intermediate shapes for complex free-form geometries since each geometry entails separate procedures due to its distinctive shape. in this study, the multistage toolpath has been constructed using three stages, including two pre-forms and the final desired geometry (table 3). each form was derived from the original cranial implant using scaling and lofting techniques. the pre-forms were developed to satisfy three critical considerations. these are: • each pre-form is characterized by a lower wall angle and depth than the successive form, see fig. 10. • the overall interaction between stages was aimed to drive the material along all three axes to allow a mohamed i. fahad al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 7287 (2023) 79 more consistent and balanced flow during the forming process. • the shifting between passes was maintained at a relatively small gap, and toolpath overlapping was avoided. table 3, the intermediate shapes and the desired geometry characteristics. fig. 10. cross section of the preforms and the final shape. the toolpath parameters are presented in table 4. the speed and feed values were selected to minimize the friction induced at the tool-sheet interface in order to prevent the tool from wearing out since it has not been heat-treated nor coated. the step-down values were increased in the initial stages in order to decrease the overall processing time. table 4, toolpath parameters fig. 11 multistage toolpath strategy: a) stage 1 b) stage 2 c) the final stage. 2.6 forming process 2.6.1 fixture and tooling the stainless-steel sheet has been mounted and fastened firmly between the upper and lower blank holders. the sheet is supported by a backing plate that has an orifice offset of 2mm from the original geometry in order to prevent excessive bending during the forming process. the forming tool used in the process is high-speed steel (hss) of 10 mm in diameter (fig. 13). fig. 12 depicts the assembled fixture accommodating the desired geometry. geometry maximum wall angle final depth preform 1 40 20mm preform 2 49 26mm desired shape 58.58 35.5mm stage step-down (mm) travel direction feed-rate (mm/min) spindle-speed (rpm) stage 1 0.4 cw 1000 100 stage 2 0.3 cw 1000 100 final stage 0.2 cw 1000 100 mohamed i. fahad al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 7287 (2023) 80 fig. 12 process fixture set-up. fig. 13 forming tool dimensions 2.6.2 fabrication a 3-axis cnc machine type c-tek (fig. 14) has been employed to carry out the forming process. the clamping fixture set-up was assembled on the x-y table and fixed firmly using clamping tools. the sheet was lubricated using oil to reduce friction at the interface between the sheet and the forming tool. fig. 15 shows the forming process and the final formed part. fig. 14. 3-axes cnc machine type c-tek machine used for the forming process. mohamed i. fahad al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 7287 (2023) 81 fig. 15. the forming process and the final produced part. 2.7 part inspection the final produced parts have been 3d scanned using the einscan-pro scanner (fig. 16), which has an accuracy of up to 0.05 mm, in order to acquire the virtual 3d model of the actual implant (mesh file) to examine and analyze the final geometrical accuracy as well as the thickness distributions across the formed part. the geometrical accuracy and thickness variation analyses have been conducted using the gom inspect software. fig. 16 the scanning process set-up. 3. results and discussion 3.1 geometrical accuracy the scanned part (stl) and the nominal cad design have been aligned in order to establish the geometrical deviation colormaps for both strategies, see fig. 17. the positive values indicate that the sheet has been over-formed, whereas areas with negative values suggest that these regions have been under-formed with respect to the nominal surface. for a thorough examination and analysis of the final geometrical results, the formed part is divided into two regions: the actual implant geometry and the surrounding surface. as can be seen, the edge of the exterior surface for the sample produced by the single-stage approach shows significant geometrical error due to over-forming. conversely, when the multistage toolpath was implemented, the formed edge aligned more correctly with the cad surface due to the gradual forming of the walls at smooth increments of depth and slope, showing improved bending characteristics. additionally, the second distinct deviation error in the single pass strategy is at the high-sloped sidewall of the auxiliary surface near the edge, which has experienced an under-forming. this error, however, has been reduced effectively when the sheet is formed at multiple forming stages. a maximum geometrical inaccuracy can be noticed in both strategies in the mutual area between the addendum surface and attached cranial implant where a smooth concave-convex transition feature is located. a cross-section analysis was utilized to examine the impact of the two approaches on this specific feature. figure 18 shows the section mohamed i. fahad al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 7287 (2023) 82 analysis of the two strategies along the curved area. both techniques have produced errors with respect to the cad model in this region. this can be attributed to the process set-up, in which the variant spif can barely maintain concave-convex transition within the formed surface. in this particular setup, the forming tool moves downward along the z-axis, imposing force in one direction without any support or opposite tool that acts as a counterforce. thus, when forming a convex feature within a container-like surface, the tool would push against this area, causing an over-forming. however, the deviations are lower in the case of the multistage toolpath. the formed cranial implant region yields negative values in the shallow areas, suggesting an under-forming of the actual geometry compared to the nominal surface when the sheet was formed using a single-pass approach. however, these distinct regions improved dramatically in the multistage strategy, showing low deviation values. this is attributed to the reduced local spring-back phenomena when the part was fabricated at multiple levels by the multistage toolpath. fig. 17 the geometrical deviations between the actual and nominal data: a) single-stage strategy b) multistage strategy fig. 18. section analysis of the geometrical accuracy: a) single-stage strategy b) multistage strategy 3.2 thickness distribution the thickness distributions of the formed parts were obtained by scanning the internal and external surfaces. subsequently, both point cloud surface data have been aligned, merged, and exported as an stl file. the thickness variation colormaps for both parts are illustrated in fig. 19. as can be noticed, as the wall angle of the geometry increases, the thickness reduction increases accordingly. this is due to the fact that steep areas drive a considerable amount of deformation compared to shallow regions. consequently, the maximum thickness reduction originated at the maximum wall angle of the geometry for both approaches. however, there is a slight difference in the thinning locations for both strategies, in which the thinning of the part produced by the multistage toolpath has shifted clockwise, i.e., with the toolpath movements for the implemented stages. moreover, the thickness at the maximum wall was distributed more efficiently in the multistage forming technique, which resulted in a less dark region compared to the traditional single-stage forming. this may be due to material shifting from shallow areas on the side wall of the geometry to the steep regions. a cross-section analysis was mohamed i. fahad al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 7287 (2023) 83 t h ic k n e ss ( m m ) (a) x (mm) employed to examine the thickness distribution across the formed region. figs 20 and 21 show the thickness values plotted in relation to the displacement at two planes (xz section and yz section). the data along the xz plane shows that the part formed by the single stage strategy has a sharp drop in thickness along the maximum wall angle in which the sheet thickness reaches a thinning of around 50% from the original sheet thickness, which results in the reduced strength of the fabricated cranial implant. on the other hand, the sample formed at multistage has shown better uniform thickness variations in that particular region with a thickness reduction of 34%. the data obtained along the yz plane appear approximately similar. overall, the results show that the part formed by the multistage toolpath approach gives a more uniform thickness distribution across the formed region compared to the traditional singlestage forming. fig. 19. thickness distribution for: a) single-stage forming b) multistage forming. x(mm) (a) x(mm) (b) mohamed i. fahad al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 7287 (2023) 84 t h ic k n e ss ( m m ) t h ic k n e ss ( m m ) y (mm) y (mm) fig. 20. thickness distributions for both strategies at xz cross-section: (a) single-stage (b) multistage y(mm) (a) y(mm) (b) fig. 21. thickness distributions for both strategies at yz cross-section: (a) single-stage (b) multistage. mohamed i. fahad al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 7287 (2023) 85 4. summary and conclusion the work established within the present paper generally deals with the manufacturing and analysis of a complex customized medical product through a well-established methodology using the single point incremental sheet metal forming by employing two forming strategies, namely, singlestage forming and multistage forming. the paper focused on studying the influence of the multistage toolpath strategy on the final formed part compared to the single-stage approach with regard to the geometrical accuracy and thickness distribution, aiming to provide a baseline understanding of the effect of the multistage toolpath approach and how it contributes to the final results. consequently, the following conclusions can be drawn from the present study: 1. the multistage toolpath strategy has significantly improved the final geometrical accuracy of the formed region. furthermore, the multistage toolpath achieved more accurate bending characteristics as well as exhibited less error in forming a convex-concave transition feature compared to the traditional single-stage method. 2. the multistage toolpath strategy achieved a more uniform thickness distribution compared to the sample produced by single-stage forming in the critical region where the maximum wall angle of the implant is located. in this area, the single-stage forming has yielded a sharp drop in thickness of 50% from the initial sheet thickness, whereas the part formed by the multistage tool path has experienced a thickness reduction of 34% in the same region. 3. although the multistage toolpath has optimized the results in terms of geometrical accuracy and thickness distribution, the strategy takes a longer lead time compared to the single-stage forming to produce the same part. the forming time required to obtain the final desired shape in the single-stage forming is roughly 59 minutes, whereas, in the multistage forming strategy, the forming time reaches around 104 minutes: the first stage forming: 16:52 minutes (16.2% of the total time). the second stage 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(2005). asymmetric single point incremental forming of sheet metal. cirp annals, 54(2), 88–114. https://doi.org/10.1016/s00078506(07)60021-3 [20] silva, m.b., nielsen, p.s., bay, n. et al. failure mechanisms in single-point incremental forming of metals. int j adv manuf technol 56, 893–903 (2011). https://doi.org/10.1007/s00170-011-3254-1 [21] tisza m. general overview of sheet incremental forming. j achiev mater manuf eng 2012;55(1):113e20 https://doi.org/10.1007/s00170-017-1397-4 https://doi.org/10.1016/j.jmrt.2020.12.014 https://doi.org/10.1016/j.proeng.2017.04.058 https://doi.org/10.1177/0309364613502071 https://doi.org/10.1016/j.cirp.2008.03.030 https://doi.org/10.4028/www.scientific.net/kem.549.223 https://doi.org/10.4028/www.scientific.net/kem.549.223 https://doi.org/10.1007/s00170-014-6143-6 https://doi.org/10.1007/s00170-014-6143-6 https://doi.org/10.1016/j.promfg.2019.06.105 https://doi.org/10.1007/978-981-15-6619-6_22 https://doi.org/10.1007/978-981-15-6619-6_22 https://doi.org/10.14733/cadaps.2019.103-112 https://doi.org/10.14733/cadaps.2019.103-112 https://doi.org/10.1007/s00170-017-1130-3 https://doi.org/10.1016/s0007-8506(07)60021-3 https://doi.org/10.1016/s0007-8506(07)60021-3 https://doi.org/10.1007/s00170-011-3254-1 (2023) 72-87، صفحة 3، العدد19لدالخوارزمي الهندسية المجمجلة محمد إبراهيم فهد 87 دراسة تأثير التشكيل متعدد المراحل على تصنيع زراعة طبية للجمجمة في التشكيل التراكمي للصفيحات المعدنية محمد إبراهيم فهد* احمد زيدان محمد** رمزية بنت مد ناصر*** *،** قسم هندسة التصنيع المؤتمت/ كلية الهندسة الخوارزمي/ جامعة بغداد/ بغداد/ العراق ماليزيا يو اس ام /جامعة /حرم الهندسة /كلية الهندسة الميكانيكية *** mohamed.ibra996@gmail.com *البريد االلكتروني: drahmed@kecbu.uobaghdad.edu.iq**البريد االلكتروني: ramdziah@usm.my :البريد االلكتروني*** الخالصة باإلضافة السريعة ةمثالي في عمليات النمذج يجعلها خيارفي تصنيع مختلف المنتجات مما عالية مرونةالتشكيل التراكمي للصفيحات يقدم بهذه ا. لكن االشكال التي يتم تصنيعهالتقليديةمع الطرق ةقليله بالمقارن يةبتكلفة انتاج المطلوبةالمنتجات حسب المواصفات مختلف الى تصنيع ةلتصنيع زراعة طبي استخدامهالتشكيل النقطي المتراكم تم ،ةدقة قليلة ونقصان كبير في السمك النهائي. في هذه الورقة البحثيظهر تالطريقة تم تقديم منهجيه لتصميم حي للمريض. شريللجزء الت يةطعالمق على الصور منطقة المفقودة من الجمجمة باالعتمادال لتالئمخصيصا ةمصمم . الهدف الرئيسي من هذا البحث هو تحليل ودراسة تأثير التشكيل على بداية من مرحلة التصميم الى تشكيل المنتج النهائي وتصنيع الزراعة الطبية بينت النهائية . النتائج وخشونة السطح والتوزيع للسمك النهائيعاد دقة االبمن ناحية ةعلى مرحلة واحد التقليدي عدة مراحل بالمقارنة مع التشكيل . فيما ةبالعينة التي تم تصنيعها من خالل مرحلة تشكيل واحد ةللسمك مقارن أفضلان العينة التي تم تشكيلها على عدة مراحل اظهرت توزيع الى ذلك التشكيل باإلضافة. للشكل المصنع ةتحليل االنحرافات اظهر ان التشكيل المتعدد ساهم في تحسين الدقة النهائي ،يخص الدقة للجزء المصنع المتعدد ساهم في زيادة خشونة السطح للشكل النهائي. mailto:mohamed.ibra996@gmail.com*البريد mailto:drahmed@kecbu.uobaghdad.edu.iq mailto:email:%20ramdziah@usm.my 1. introduction [1] baden, a. s. (2017). optimization and prediction of process parameters in spif that affecting on surface quality using simulated annealing algorithm. al-khwarizmi engineering journal, 12(4),8192. https://doi.org/10.22153/kej.2016.05.005 [2] jabber, a. s. (2019). investigation the effect of process variables on the formability of parts processed by single point incremental forming. al-khwarizmi engineering journal, 14(2), 58 70. https://doi.org/10.22153/kej.2018.12.003 this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 19, no. 2, june, (2023) p. p. 114 citric acid production: raw material, microbial production, fermentation strategy and global market: critical review ramzi a. abd alsaheb* malik mustafa mohammed** jaafar kamil abdullah *** azza hashim abbas**** * department of biochemical engineering / al-khwarizmi college of engineering/ university of baghdad/ baghdad/ iraq **al-mustaqbal university/ babylon/ iraq ****school of mining and geosciences/ nazarbayev university/ kazakhstan *email: ramzi.a@kecbu.uobaghdad.edu.iq **email: dr.malikmustafa@mustaqbal-college.edu.iq ***email: drjafar2@basrah-college.edu.iq ****email: azza.hashim@nu.edu.kz (received 28 september 2022; accepted 19 december 2022) https://doi.org/10.22153/kej.2023.12.002 abstract citric acid is an essential ingredient for the manufacture of (12) key industrial chemicals. citric acid use is increasing steadily with a high annual growth rate as a result of the development of ever more sophisticated applications. citric acid is widely utilized in the food and pharmaceutical industries due to its low toxicity when compared to other acidulous. other uses for citric acid can be found in cleaning supplies and detergents. based on information from a review of the literature, citric acid production substrates and methods for surface fermentation, submerged fermentation, solid-state fermentation, and international market expansion are all covered in the current review study. finally, there is still much to learn about the circumstances of the production of citric acid from raw materials, microorganisms, and fermentation techniques to achieve the best production in terms of cost and quality. keywords: citric acid, food applications, pharmaceutical applications, fermentation. 1. introduction in 1893, the botanist (carl wehmer) discovered that the penicillium mold could produce ca on sugar medium [1]. carl wehmer discovered two new fungal strains having the capacity to accumulate ca after a period of timeterm, which named citromyces (penicillium) [2] however, because of contaminant problems and a prolonged fermentation time, industrial testing were unsuccessful. wehmer's publications were known to currie, a dairy scientist at the usda, who looked at a number of other molds. carl wehmer observed that a. niger, when grown on media with a low ph, high sugar content, and mineral salts, perfectly produces citric acid. currie's breakthrough paved the gate for the profitable industrial manufacturing of ca [3]. the most important finding was that a. niger thrived in ph ranges of 2.5 to 3.5 and that high sugar concentrations promoted citric acid production [4]. since ancient times, citric acid abounds in iraq on palm dates, especially dates (zahdi) in large proportions. it is fermented by aspergillus niger for 48 h under operating conditions to produce large quantities of citric acid of high quality and reasonable costs [5]. mailto:ramzi.a@kecbu.uobaghdad.edu.iq mailto:dr.malikmustafa@mustaqbal-college.edu.iq mailto:dr.malikmustafa@mustaqbal-college.edu.iq mailto:drjafar2@basrah-college.edu.iq mailto:drjafar2@basrah-college.edu.iq mailto:azza.hashim@nu.edu.kz https://doi.org/10.22153/kej.2023.12.002 ramzi a. abd alsaheb al-khwarizmi engineering journal, vol. 19, no. 2, p.p. 114 (2023) 2 the first citric acid fermentation process was carried out in surface cultures [6]. for commercial production, some units were installed in england and germany in the 20th century [7]. typically, molasses is fermented by submerged microbial organisms to create citric acid for commercial use [8]. the primary method for producing citric acid worldwide is still fermentation using aspergillus niger [9]. although methods for synthesizing ca via chemical means were well-developed, microbial fermentation saw better success over time, and over time, this technology has supplanted chemical synthesis as the best option for its commercial production [10]. despite this, there are many of issues with the introduction of submerged fermentation, choosing productive breeds that are less sensitive to trace elements. it was required to think considerably more thoroughly about the basic materials. the conditions for using inexpensive materials such starch, sugar cane molasses, beet molasses and hydrolysate starch have been optimized in many of publications [11, 12, 13, 14,]. molasses treatment and purification methods have been developed, particularly for the removal of trace metals. additionally, it was discovered that a slight excess of copper ions helped produce high yields of citric acid. the demand for citric acid is increasing annually by 3.5–4.0%. in the last years, there has been a lot of interest in using agricultural wastes, such as those from the production of ca, such as those from the production of maize [15], [16], apple [17], [18], grape [19], [20], pineapple [21], [22], orange [23], [24], brewery wastes [25], [26], citrus [27], [28], and cassava [29], [30]. the market is looking for more recent, affordable, and efficient process technologies. one of the most significant commercially added-value products is citric acid, a krebs cycle intermediary that finds use in the food processing sector (70%), the pharmaceutical industry (12%), and other industries (18%) [31]. citric acid, also regarded as a chemical that is generally recognized as safe (gras), non-toxic, and pleasing to the taste. citrus fruits like limes, lemons, grapes, oranges, and tangerines are naturally home to (ca). citric acid is a continuously needed ingredient in the food business for usage as an acidulant, antioxidant, preservative, and emulsifier in various food items. citric acid is so consistently employed as a standard ingredient in a wide range of food products, is a healthy molecule, and is highly demanded for daily consumption worldwide [32]. finally, a variety of physical and chemical techniques were admitted for producing ca. however, it has been found that such conventional methods are both pricey and complex, and they are not ecological [33,34]. additionally, when demand is strong, the annual production rate of ca is lower. in order to satisfy market demand, it is crucial for ca production to remain constant. 2. properties all aerobic organisms use citric acid, or (2hydroxypropane-1,2,3-tricarboxylic acid), as an intermediary in their metabolic cycle [35]. the molecular weights of citric acid's anhydrous (c6h8o7), monohydrate (hoc(cooh)(ch2cooh)2.h2o), molecular weight (210.14) and molecular weight 192.12). white crystalline powder, respectively [36]. monohydrate ca is sparingly soluble in ether, ethanol and sparingly soluble in both ethanol and water, ca is solid, boils at 310°c and melts 153°c at room temperature [37],[38]. it decomposes with a loss of mass above approximately 175°c (co2). it has a strong acid flavor that affects sweetness and adds a fruity tartness once dissolved in water. for these reasons, it is commonly used in the food and beverage industries to enhance fruit flavors. the acid exhibits excellent buffering capacity when combined with citrate, and its excellent metal ions chelating properties add to the physicochemical characteristics that make it ideal for food, pharmaceutical and cosmetic applications. the sheer number of these uses attests to the acid's exquisite versatility [39]. fig. 1. citric acid structure. ramzi a. abd alsaheb al-khwarizmi engineering journal, vol. 19, no. 2, p.p. 114 (2023) 3 microbiological conversion of acids like (citric acid) to cellular material and other useful products is fermentation.[40],[41]. even though it is an outdated technology, scientific advancements have kept this procedure at the forefront. the conversion process has advantages because it uses renewable resources, makes it easier to use waste for constructive purposes, and creates useful byproducts. it uses less energy and involves relatively mild environmental conditions. additionally, it has some shortcomings, some of which are : a-utilization of a lot of water. b-the garbage needs to be treated before disposal due to its high bod. c-foreign microorganism contamination can lower the yield, and the technology is advanced. 3. citric acid synthesis by microorganisms microorganisms several microorganisms, including bacteria and fungi, have been used to produce citric acid, including bacillus licheniformis [42,43], aspergillus niger [44,[45], and yarrowia lipolytica [46,47]. the bulk of them, however, are unable to provide commercially acceptable yields due to the fact that citric acid is a byproduct of energy metabolism and that its accumulation only increases in significant amounts under conditions of extreme imbalances. aspergillus niger has continued to be the strain of choice for commercial production among those indicated since it generates more citric acid per period of time [48]. the simultaneous synthesis of isocitric acid presents a challenge in the manufacture of citric acid for yeasts. a literature review found that various microorganisms must use inexpensive basic materials as substrate to transform them into products with added value, including organic acids and other goods. specifically, aspergillus niger produces weak organic acids such as citric acid and gluconic acid [49]. the predominant black aspergillus species used in this sort of manufacturing. the main reason for choosing because of what was mentioned in the literature [50]. there aren't many commercial citric acid producing industrial strains out there, and just a few may be found in foreign culture collections. by using mutagenesis and selection, citric acidproducing microorganisms have been improved. the method that has been used the most frequently is to use mutagens to cause mutations in parental strains [51]. a. niger mutants are employed in industrial production. uv radiation, g-radiation, and chemical mutagens are the most often using mutagens. a single strain of bacteria can produce various amounts of citric acid depending on the fermentation technique used. therefore, a strain that produces well in surface fermentation of solids or liquids may not always produce well in submerged fermentation. each industrially applicable technique and raw material should thus be examined using known producer strains [52]. spores that are supplied to the fermentation medium are utilized to inoculate the microorganisms in any method used to produce citric acid [53]. the air that is delivered into the substrate can be mixed with spores to inoculate it, or spore suspension can be used instead glass vials with solid substrates and the ideal temperature are used to manufacture spores [54]. in terms of spore viability and citric acid synthesis, the kind of sporulation media and incubation period have an impact on the mycelia formed from a. niger. also, can produce citric acid from potato dextrose agar. after less than one week of spore incubation, viability increases, the ability of the spores to germinate tends to decline over time, but in certain instances, brief intervals of up to 7-8 days do not show a discernible difference from spores collected after 3 days [55]. in addition, there is a lot of interest in recent developments on the capacity of various yeast strains to make citric acid. for the past four decades, investigations on various aspects of yeasts have been the main emphasis. these studies have numerous positive correlations to fungal processes but are also infrequently utilized in business. table (1) lists the bacteria, fungus, and yeast strains that production citric acid. ramzi a. abd alsaheb al-khwarizmi engineering journal, vol. 19, no. 2, p.p. 114 (2023) 4 table 1, citric acid producing organisms. microorganism strains producing ca references (bacteria) arthrobacter paraffinens, corynebacterium sp., bacillus subtilis, brevibacterium flavum, corynebacterium sp bacillus licheniformis acetobacter xylinum [56]-[59] (fungi) a. niger, a. aculeatus, a. awamori, a. carbonarius, a. wentii, penicillium oxalicum a. niger a. niger atcc12846 [60]-[63] (yeast) saccahromicopsis lipolytica, lipolytica 1.31 y. lipolytica ng40/uv5 candida lipolytica [64]-[67] 4. different processes for citric acid production more than 95% of the citric acid generated globally today is derived through fermentation process [68]. citric acid is best produced by the filamentous aspergillus. niger, which is also a powerful producer. the three steps that make up the production of citric acid are preparation and inoculation of the fermentation broth, fermentation, and recovery/purification of the product. three most common methods for manufacturing citric acid are submerged fermentation (smf), surface fermentation (sf), and solid-state fermentation (ssf), as already depicted in fig (2). depending on the kind of fermentation, many citric acid fermentation techniques exist. fig. 2. different processes for citric acid production [68]. from other side, as shown in fig 3 there are many of the variables effective on productivity of citric acid include: carbon source [69], nitrogen and phosphate limitations [70] ph of culture medium [71], aeration [72], trace elements [73]. ramzi a. abd alsaheb al-khwarizmi engineering journal, vol. 19, no. 2, p.p. 114 (2023) 5 fig. 3. variables effective on productivity of citric acid [69 -73]. 4.1 surface fermentation bacteria grow on the surface of the fermentation media during surface fermentation (sf(. over the surface of the media used in the surface fermentation process used to make citric acid, a. niger creates a thick floating mycelial mat. many small and medium sized industries employ surface fermentation because it is easier to operate, uses simpler equipment, and uses less energy [74], [75]. in the fermentation chambers where the process is run, many trays are arranged on shelves. the trays can be composed of high purity aluminum, steel of a certain type, or polyethylene, however steel trays offer higher citric acid yields [76]. evaporative cooling is used to effectively manage humidity and temperature on the surface of the fermentation chambers. the chambers must always be protected and kept under aseptic conditions, especially during the first two days when spores proliferate [77]. an antibacterial filter is used to filter this air. aspergilli, penicillia, yeasts and lactic acid bacteria are the principal culprits behind the most prevalent contamination. high aeration rates are necessary to maintain temperature control and provide the microorganisms with air during fermentation, which takes 1-2 weeks to complete [78]. the contents of the tray are split into a mycelial mat and rough fermentation broth after fermentation. the mycelial mats are next cleansed to eliminate the material that had been impregnated with citric acid. surface fermentation is less advantageous than submerged fermentation in terms of yield, labor intensity, and maintenance costs [79]. it is especially vulnerable to changes in the makeup of the media. less energy is used during surface fermentation, and there is no foam [80]. 4.2 submerged fermentation through the sf process, the organism can develop across the liquid broth medium that is housed inside the nutrient substrate [81]. the fermentation process is carried out in bioreactors and achieved within 5-12 days [82]. after one to two days of inoculation, the organism develops into pellets that are freely suspended in the medium and have a diameter of around 0.5 cm. therefore, an organism with a large surface area of contact can absorb nutrients and oxygen. a high-speed air flow is delivered into the vessel to increase the amount of oxygen. the air bubbles are then mixed and broken up by agitation equipment. the bacteria in the medium break down the carbon source anaerobically or partially anaerobically [83]. superior fermentation process control and efficient usage of a variety of substrates are two of sf's primary benefits [84]. it provides lower capital, maintenance, higher production, and contamination less risks make it more suitable for citric acid production [85]. on the other hand, the disadvantage of sf is the creation of foam, which can be reduced by using antifoam agents such animal or plant fats and chambers with quantities up to one-third of the total volume of the fermenter [86]. 4.3 solid state fermentation citric acid production process by use solid state fermentation (ssf) has garnered a lot of attention lately since it has several benefits for the production of enzymes and bulk chemicals [87,88,89]. solid state processes require less energy, generate a lot less effluent, and offer less of a threat to the environment, which accounts for a portion of this. ssf, a fermentation process, is required for bacteria to flourish on solid surfaces ramzi a. abd alsaheb al-khwarizmi engineering journal, vol. 19, no. 2, p.p. 114 (2023) 6 in the absence of free liquid. ssf has the moisture needed for microbial growth, but it is absorbed or complexes inside the solid matrix [90]. this solid substance is typically a natural mixture made up of by products and residues from the agroindustrial and agricultural sectors, synthetic substance or a sediment. erlenmeyer conical flasks [91], glass incubators [92], trays [93], single layer packed bed [94], packed bed column bioreactor [95], and double stage packed column bioreactor [96] are only a few examples of technique of the fermenters that have been using to produce citric acid in ssf process. on the hand, when compared to submerged fermentation, the main benefits of solid state fermentation include, a higher production, a lower risk of pollution, lower energy, less potential for downstream processing, simplicity of operation, minimal stream generation, lower operating costs and operability under less water amounts [97]. additionally, as the system is less sensitive to the presence of trace elements than submerged fermentation, the solid state fermentation technique enables the uncomplicated use of affordable and readily available agro-industrial substrates without the need for pre-treatment [98]. table 2, comparison of the production of ca using various fermentation techniques. fermentation process advantage disadvantage references ssf increased production, cheaper energy and media, improved oxygen flow during installation, and less work during operation, less susceptible to the suppression of trace elements and less post-recovery, little chance of microbial pollution from waste. difficult parameter control and greater recovery product costs. [99]-[102] smf advanced possess control systems, decrease labor costs, greater productivity and yield costly media, large amounts of waste water production, and sensitivity to trace metal inhibition. [103]-[107] sf lower operating costs and energy costs. large heat production, space intensive, long time, and susceptible to contamination by yeasts, lactic acid bacteria, penicillium, and fungi. [108]-[112] 5. citric acid global market citric acid one of the most famous natural acids, ca is a weak acid and found naturally in citrus fruits including lemons, orange and limes. it performs as a food additive and a safe preservative, helping to stabilize and preserve food products. additionally, prevents beverage degradation and promotes emulsion preservation [113]. the global citric acid market is projected to reach usd 9 billion by 2030, growing at a compound annual growth rate (cagr) of 5.90% for the anticipated period from 2023-2030, according to all available industry data and the development of contemporary industries in agriculture, food, and pharmaceuticals [114]. the expansion of food additives in the processed food industry has a direct impact on the ca market. during the predicted years, there is expected to be a continued high level of consumer demand for food and beverage products made using safe components. ca is being used more frequently in the pharmaceutical and cosmetics industries, which is increasing the market demand for items containing it. citric acid helps producers meet consumer demand for safe and acceptable products while maintaining within their budgets and offering a save organic for their goods [115]. the industry is expanding due to rising consumer demand for organic food additives and changing customer preferences. phosphate, which was formerly used, has been replaced by ca, which has increased the market. however, producers face fierce rivalry for raw materials from both outside and inside the industry, which significantly limits the growth of the citric acid market. because of these advantages and the wide industrial applications of citric acid, the demand for it in the future will remain rapidly and growing as one of the best influential acids in the modern global market. ramzi a. abd alsaheb al-khwarizmi engineering journal, vol. 19, no. 2, p.p. 114 (2023) 7 fig. 4. market for citric acid anticipated to reach $9 billion globally [114]. 6. conclusion citric acid has a wide range of applications as a versatile and secure alimentary addition across a variety of commercial sectors, including the chemical, pharmaceutical, cosmetic, and food industries. to fulfill the escalating demand for citric acid, there is an urgent need for production methods that are both affordable and environmentally friendly. it will take some time to fully comprehend the mechanics and characteristics of citric acid, and it must be generated in ways that ensure its sustainability, abundance, and excellent quality. 7. references [1] b. igliński, u. kiełkowska, and g. piechota, “proecological aspects of citric acid technology,” clean technologies and environmental policy, vol. 24, no. 7, pp. 2061–2079, apr. 2022, doi: 10.1007/s10098022-02316-y. 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(2023) 1-14، صفحة 2لعددا، 19مجلة الخوارزمي الهندسية المجلد رمزي عطا عبد الصاحب 14 :العالمية قوالسو التخمير واستراتيجية الميكروبي واإلنتاج الخام المواد: الستريك حامض انتاج نقدية مراجعة **مالك مصطفى محمد * رمزي عطا عبد الصاحب ****عزه كامل عباس ***جعفر كامل عبد هللا *قسم الهندسة الكيمياوية/ كلية الهندسة الخوارزمي/ جامعة بغداد/ بغداد/ العراق **قسم الهندسة الكيمياوية والصناعات النفطية/ كلية المستقبل الجامعة/ بابل/ العراق **جامعة نزارباييف/ كازاخستان** ramzi.a@kecbu.uobaghdad.edu.iq :البريد االلكتروني* dr.malikmustafa@mustaqbal-college.edu.iq*البريد االلكتروني: drjafar2@basrah-college.edu.iq :البريد االلكتروني*** azza.hashim@nu.edu.kz :البريد االلكتروني**** الخالصة نتيجة مرتفع سنوي نمو بمعدل مطرد بشكل الستريك حامض استخدام يتزايد. رئيسية صناعية كيميائية مادة( 12) لتصنيع أساسي مكون الستريك حامض عند المنخفضة لسميته نظًرا والصيدالنية الغذائية الصناعات في واسع نطاق على الستريك حامض يستخدم. مضى وقت أي من تعقيدًا أكثر تطبيقات لتطوير من المستمدة وماتالمعل إلى استنادًا. والمنظفات التنظيف مواد في الستريك لحمض أخرى استخدامات على العثور يمكن. األخرى بالحمضيات مقارنته كلها الدولية السوق وتوسيع الصلبة، الحالة في والتخمير المغمور، والتخمير السطح، تخمير وطرق الستريك حامض إنتاج ركائز فإن األدبيات، مراجعة تخميرال وتقنيات الدقيقة كائناتوال الخام المواد من الستريك حامض إنتاج ظروف عن لنتعلمه الكثير هناك يزال ال أخيًرا،. الحالية المراجعة دراسة في مغطاة .والجودة التكلفة حيث من إنتاج أفضل لتحقيق mailto:ramzi.a@kecbu.uobaghdad.edu.iq mailto:dr.malikmustafa@mustaqbal-college.edu.iq**البريد mailto:drjafar2@basrah-college.edu.iq***البريد mailto:drjafar2@basrah-college.edu.iq***البريد mailto:azza.hashim@nu.edu.kz****البريد mailto:azza.hashim@nu.edu.kz****البريد this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 20, no. 3, september, (2024), pp. 1-10 electrochemical extraction with supported liquid membrane for removing copper from synthetic wastewater: optimisation through response surface methodology noor r. kadhim*, hussain m. flayeh**, ali h. abbar*** and hasan f. al-azzawie**** *,**environmental engineering department, college of engineering, university of baghdad, iraq ***biochemical engineering department, al-khwarizmi college of engineering, university of baghdad, iraq ****lincoln university, malysia *email: noor.jabbar2011d@coeng.uobaghdad.edu.iq (corresponding author) **email: hussain-altemmimi@coeng.uobaghdad.edu.iq ***email: ali.abbar@kecbu.uobaghdad.edu.iq ****email: hazzawie2@yahoo.com (received 26 november 2023; revised 4 april 2024; accepted 2 july 2024; published 1 september 2024) https://doi.org/10.22153/kej.2024.07.001 abstract in this study, copper was removed from an aqueous solution through electromembrane extraction (eme), a new approach that utilises a two-chamber electrochemical cell. it consists of two electrodes (stainless steel cathode and graphite anode) and a solid liquid membrane (slm). slm is composed of supporting polypropylene membrane impregnated with1-octanol as an organic solvent and bis(2-ethylhexyl) phosphate (dehp) as a carrier. the effects of process parameters such as applied voltage, ph and copper concentration on the removal of copper were investigated. response surface methodology (rsm) was applied to optimise these parameters and their interactions. results indicated that ph has the major effect on the removal of copper, followed by applied voltage. the squared interaction term in the rsm model has the highest contribution (70.5%), followed by the linear term, thereby confirming the significant interaction among the variables. the optimum conditions include an applied voltage of 60v, ph of 5.18 and initial copper concentration of 5 ppm, which yield to a removal efficiency of 80% after 6 hours of operation. the findings demonstrate the use of electromembrane extraction as an efficient method for the removal of heavy metals and provide valuable insights for future application to other environmental and water treatment processes. keywords: electromembrane extraction, copper; slm; rsm, dehp;1-octanol 1. introduction increasing environment pollution in the international ecosystem is a major concern that should be resolved [1]. main contaminants of water are heavy metals, which cause several public health issues. most heavy metals are present in the industrial wastewater and are highly resistant to degradation [2,3]. in addition to entering the body through the skin, these metals could enter through food and drink [4,5]. they are poisonous and can harm the brain and central nervous system as well as the kidneys, liver, lungs, blood and other essential organs [6]. copper is a heavy metal that generates serious environmental hazards [6]. wastewater from metal finishing, textile and electronic industries may contain copper at concentrations up to 500 mg/l. based on the global environmental regulations, this concentration is higher than the permissible level; hence, wastewater containing copper must be treated before being discharged into the environment [7]. mailto:noor.jabbar2011d@coeng.uobaghdad.edu.iq mailto:hussain-altemmimi@coeng.uobaghdad.edu.iq mailto:ali.abbar@kecbu.uobaghdad.edu.iq mailto:hazzawie2@yahoo.com https://doi.org/10.22153/kej.2024.07.001 noor r. kadhim al-khwarizmi engineering journal, vol. 20, no.3, p.p. 110 (2024) 2 copper ions are removed using different methods, such as adsorption, chemical precipitation, membrane separation and electrochemical methods (electrocoagulation and/or cathodic deposition) [8]. each method has its own advantages and disadvantages, but most of them can be costly and incapable of treating low concentrations of copper ions [8,9]. recently, membrane extraction technology is regarded as an effective separation technique. it combines the advantages of extraction and membrane separation. in this method, heavy metals can diffuse from a high-concentration chamber (donor phase) through a membrane to a lowconcentration chamber (acceptor phase) as a result of concentration difference across the membrane. liquid–liquid extraction underlies the operation of liquid membrane (lm) technique and exhibits advantages such as excellent selectivity, energy efficiency and environmental protection [10]. this method offers a high extraction efficiency for metal ions. different types of membranes include bulk liquid membranes (blm), emulsion liquid membranes (elm), supported liquid membranes (slm) and polymer inclusion membranes (pim) [11,12]. slm is based on solid polymer materials and does not require the extensive use of extraction agents or intricate steps involved in traditional approaches, such as demulsification and emulsion preparation. its advantages in selectively separating and enriching low concentrations of heavy metals in high-matrix background are numerous, energy-efficient, and environmentally friendly [13]. fast heavy metal transport from the donor phase to the acceptor phase can occur when an electric field is applied over slm [14]. the apparatus is known as electromembrane extraction (eme), where the donor and acceptor phases are submerged in two platinum electrodes that are powered by a power source [13,14]. the two types of eme used for extraction of heavy metals are hollow fibre and flat membrane, and the latter is preferred for scale up [15]. in the removal of heavy metals, eme is applied to remove diverse cations for different solutions [16,17]. however, literature on the application of flat membranes for removing copper is limited. moreover, the most suitable type for scale up is rare and has limited supply. this work aims to apply a flat eme for removing copper from an aqueous medium on a laboratory scale. a brand-new two-chamber cell with a flat sheet membrane was adopted as an easy and cost-effective cell design because it used inexpensive electrodes (graphite anode and stainless-steel cathode) and slm, instead of platinum electrodes. the effect of several parameters including applied voltage, donor ph and initial copper concentration on removal efficiency were investigated through response surface methodology (rsm). in this powerful experimental design, the interactions among variables can be recognised as impossible to be determined by the traditional one factor at one time approach, which requires a high number of runs. 2. experimental 2.1 chemicals all chemicals used were of analytical grade. cuno3 was purchased from central thomas baker, mumbai, india. deionised water was used as solvent to create acceptor and donor phase solutions. 1. octanol was utilised as organic solvent in the liquid membrane and was obtained from central drug house, delhi, india. bis(2ethylhexyl) phosphate (dehp) was purchased from shanghai macklin biochemical and used as the carrier in slm (shanghai, china). a polypropylene membrane sheet with a pore diameter of 0.1 microns and a thickness of 0.18– 0.22 mm was utilised as supportive liquid membrane. it was supplied by jian city qing feng equipment material co. in china. hcl and naoh were provided by thomas baker, ambernath, india. 2.2 electromembrane extraction system figure 1 depicts the electrochemical apparatus, which consists of two symmetrical chambers with a volume of 137.44 cm3 each. the first chamber was utilised as a donor phase, while the second chamber was utilised as an acceptor phase and had an active volume of 100 cm3. both chambers were 5 cm in diameter and 7 cm in length and had a lateral channel (3 cm in diameter and 3 cm in length) positioned 2 cm above the chamber base. each chamber has a teflon cup (4.8 cm in diameter and 10 mm in thickness). graphite was adopted as the anode because it facilitates water decomposition by anodic oxidation[18]. stainless steel, which is less expensive than platinum electrodes, was used as a cathodic material. slm is composed of polypropylene membrane sheet with an active surface area of 7 cm2 and was impregnated for 15 minutes with 1-octanol solvent and a suitable carrier. slm was fixed in the space between the chambers and secured via two teflon noor r. kadhim al-khwarizmi engineering journal, vol. 20, no.3, p.p. 110 (2024) 3 cups, four screws and netting. two magnetic stirrers (metrohm ag herisau, switzerland, type: 18490010) were placed inside the chambers for mixing at 1000 rpm. the eme was run at various applied voltages using a uni-t/utp3000 power supply (hong kong). the exact current value was determined with a uni-t connected ammeter (kowloon, hong kong) [15]. magnetic stirrer magnetic stirrer power supply ammeter donor chamber accepter chamber silicone rubber membrane stainless steel cathode graphite anode fig. 1. eme system 2.3 analysis and measurements the samples were analysed using an aa-7000 atomic absorption spectroscope (shimadzu, japan) to ascertain the concentration of copper ions. the efficiency of copper removal was evaluated using eq. 1 [18]: 𝑅𝐸(%) = 𝐶𝑖−𝐶𝑓 𝐶𝑖 × 100 … (1) where ci is the initial concentration of cu in part per million, and cf is the final concentration of cu measured after completing the run at time δt. in this work, the electrolysis time was set to 6 hours based on a preliminary run conducted at the midpoint, during which a jump did not occur in the current. this finding demonstrated that the liquid membrane did not begin to leak into the solution [19]. 2.4 experimental design rsm based on box–behnken design (bbd) is a widely used experimental tool to correlate process variables and response in statistical and mathematical settings. compared with the conventional one factor at a time strategy, rsm requires fewer runs, resulting in an experimental program that is more economical and time efficient [20]. bbd, which is based on three-level parameters, was used to optimise the process parameters. re percent was used as response, and process variables included voltage (x1), ph (x2) and initial copper concentration (x3). the maximum value of each process variable was set at (+1), the middle value was set at (0) and the lower value was set at (-1) [21]. the process variables and their chosen values are shown in table 1. an array of runs based on bbd was created using minitab17 software. table 1, process factors (coded and real levels). process factors range in bbd coded levels low(-1) middle(0) high(+1) applied voltage (volt),x1 20 40 60 ph,x2 3 5 7 concentration of copper (ppm),x3 5 15 25 noor r. kadhim al-khwarizmi engineering journal, vol. 20, no.3, p.p. 110 (2024) 4 a quadratic equation that relates the process factors with responses is shown in eq. 2[22]. 𝑌 = 𝑎0 + ∑ 𝑎𝑖 𝑥𝑖 + ∑ 𝑎𝑖𝑖 𝑥𝑖 2 + ∑ 𝑎𝑖𝑗𝑥𝑖𝑥𝑗 …(2) the intercept term is 𝑎0, and j and i stand for the index numbers for the patterns. ai and aii represent the first-order (linear) and second-order effects. the interaction effects are represented by aij. the coded process factors are 𝑥1.,𝑥2..,𝑥𝑘. finally, y is the response term. based on anova, a regression coefficient (𝑅2) can be used to evaluate the fitting of eq. 2. 3. results and discussion 3.1 statistical results rsm with bbd was used to simulate and optimise the removal of copper by eme. fifteen runs were completed, and the results are displayed in table 2. a second-order quadratic model was built using rsm in terms of real values of the parameters (eq. 3). table 2 also presents the anticipated values of re derived from equation 3. 𝑅𝐸% = −37.62 + 0.134 𝑥1 + 44.02 𝑥2 − 2.062 𝑥3 + 0.00301 𝑥1 ∗ 𝑥1 − 4.050 𝑥2 ∗ 𝑥2 + 0.04931 𝑥3 ∗ 𝑥3 − 0.0378 𝑥1 ∗ 𝑥2 + 0.00165 𝑥1 ∗ 𝑥3 + 0.0336𝑥2 ∗ 𝑥3 …(3) the results showed that re% ranged from 40.98% to 80%. as a preliminary evaluation of the effects of parameters, increasing the applied voltage increased re% (compared between runs 5 and 12). increasing the concentration of copper decreased re% (compared between runs 5 and 11). increasing the ph from 3 to 7 led to higher removal of re% (compared between runs 6 and 2). however, the real effects of these parameters and their interaction were only assessed using anova combined with response surface plots. table 2, optimisation of copper removal by rsm run order pt type blocks applied potential (v) ph initial concentration (ppm) re% actual predicted 1 2 1 40 7 5 64.3 64.080 2 2 1 60 7 15 61.03 60.241 3 0 1 40 5 15 67.53 67.510 4 0 1 40 5 15 70 67.510 5 2 1 60 5 5 80 81.009 6 2 1 60 3 15 53.33 53.209 7 2 1 40 3 5 56.26 55.373 8 2 1 20 3 15 40.98 41.769 9 2 1 20 7 15 54.72 54.841 10 2 1 40 3 25 46.84 47.060 11 2 1 60 5 25 74.8 74.701 12 2 1 20 5 5 73.15 73.249 13 0 1 40 5 15 65 67.510 14 2 1 40 7 25 57.57 58.458 15 2 1 20 5 25 66.63 65.621 anova was used to assess the acceptability of bbd. fisher’s f and p tests were adopted to establish the significance of the model and its parameters [22]. in general, a high significance for the coefficient terms is indicated by large f values and small p values [23]. table 3 presents the anova for the response surface model. contr. % indicates the percentage contribution of each variable; df denotes the degree of freedom of the model and its parameters; the terms “the adjusted mean of square (adj. ms)”, “adjusted sum of square (adj. ss)” and “sum of square (seq. ss)” represent the statistical terms for the model. the estimated f value of 50.09 and p value of 0.0001 indicated the high significance of the regression model. the regression r2 was 0.989 which is statistically significant and only (0.011) of the total variance not confirmed by the model [24]. noor r. kadhim al-khwarizmi engineering journal, vol. 20, no.3, p.p. 110 (2024) 5 table 3, analysis of variance for copper removal 𝐒𝐨𝐮𝐫𝐜𝐞 𝐃𝐅 𝐒𝐞𝐪. 𝐬𝐬 𝐂𝐨𝐧𝐭𝐫. % 𝐀𝐝𝐣. 𝐬𝐬 𝐀𝐝𝐣. 𝐌𝐬 f-value p-value model 9 1578.01 98.90 1578.01 175.335 50.09 0.0001 linear 3 440.99 27.64 440.99 146.997 42.00 0.001 (x1) 1 141.79 8.89 141.79 141.793 40.51 0.001 (x2) 1 202.11 12.67 202.11 202.106 57.74 0.001 (x3) 1 97.09 6.09 97.09 97.092 27.74 0.003 square 3 1125.66 70.55 1125.66 375.218 107.20 0.0001 "x1 ∗ x1" 1 15.06 0.94 5.35 5.350 1.53 0.271 "x2 ∗ x2" 1 1020.81 63.98 968.86 968.860 276.80 0.0001 "x3 ∗ x3" 1 89.79 5.63 89.79 89.787 25.65 0.004 2-way lnter. 3 11.37 0.71 11.37 3.788 1.08 0.436 x1 ∗ x2 1 9.12 0.57 9.12 9.120 2.61 0.167 x1 ∗ x3 1 0.44 0.03 0.44 0.436 0.12 0.739 x2 ∗ x3 1 1.81 0.11 1.81 1.809 0.52 0.504 error 5 17.50 1.10 17.50 3.500 lack of fit 3 5.00 0.31 5.00 1.667 0.27 0.847 "pure-error" 2 12.50 0.78 12.50 6.250 total 14 1595.51 100.00 model-summary s. r2 r2(adj.) press r2(pred.) 1.87088 98.90% 96.93% 108.133 93.22% table 3 shows that ph has a high contribution to the linear part of the model, followed by applied voltage and initial copper concentration. however, the model’s second term showed a significant contribution of ph with high contribution of 63.98%. the applied voltage had a small impact with a contribution of 0.94%. the interaction term was the most dominant in the model, confirming that the relation between removal efficiency and operating parameters is not linear and a significant interaction exists. in this experiment, the lack of fit was statistically non-significant. the model produced reliable predictions that match well with the response values [25]. 3.2 influence of process factors on copper removal efficiency the effects of particular variables on responses can be seen visually with the use of rsm graphics. the effects of applied voltage and initial copper concentration on the removal efficiency of copper at a constant ph of 5 are displayed in figures (2-a and 2-b). figure 2-a shows the surface response plot, while figure 2-b shows the contour plot. the surface plot verifies that for all copper concentrations tested, an increase in re percent occurs as the applied voltage increases, and the relationship appears to be linear. this phenomenon may be explained by the enhancement in the mass transfer of copper across the membrane between the two phases due to the formation of more cu (ii)-deehpa complexes inside slm, where their movements increased by applying higher voltages. similar findings were published by meng et al. in 2021 [26] when they used eme for cadmium removal. they also discovered that 6.0 v was the optimal applied voltage. similar observation was found by kadhim et al. in 2023[9] for the removal of zinc by using eme with slm. (a) 6 12 18 56 07 57 20 42 04 60 57 80 re% ntial (v)etop deilppa ecnoci liatin tration(ppm)n noor r. kadhim al-khwarizmi engineering journal, vol. 20, no.3, p.p. 110 (2024) 6 (b) fig. 2. effect of applied potential and initial concentration on copper removal efficiency: a) surface plot, b) contour plot (hold: ph=5) the percentage of re decreased when the initial copper concentration decreased from 25 ppm to 15 ppm, after which it began to gradually increase as the concentration further decreased down to 5 ppm. an exponential relationship was found between re percent and starting concentration when the copper concentration decreased from 5 to 15 ppm. these findings are consistent with the findings of swain et al. (2007) [27] and are true even when in the absence of an electrical current. this work also demonstrated how well the chosen carrier, dehp, facilitated the diffusion-driven passage of copper ions across the membrane. the results provide evidence for the effectiveness and suitability of dehp as a carrier for eme [27]. based on the associated contour plots, an area with an applied voltage between 58 and 60 v and an initial concentration of (5–6 ppm) led to 80% re. figures 3-a and b show the effects of applied voltage and ph at an initial copper concentration of 15 ppm. the percentage of re increased as the ph increased from 3 to 5 and then started to decrease thereafter (figure 3-a). these results imply that the most apparent effective copper–dehp bonding occurred at ph 5, suggesting that this is the ideal ph in 1-octanol [28]. interestingly, dehp undergoes more protonation when the ph is below 5, preventing it from effectively interacting with ions [26]. at high ph values, cu (ii) tends to form complex species, which hinders its passage across the membrane. previous studies confirmed that releasing heavy metals into an acidic medium is better than releasing it in a neutral and/or an alkaline medium [28]. meng et al. [26] reported the same behaviour in removal of cd. kadhim et al. [9] also stated similar behaviour in the removal of zinc using eme with slm. davarani et al. [15] found that an alkaline medium is preferred for the removal of cd2+, zn2+ and co2+ by using membrane containing mixed carriers (dehp and tehp). the corresponding contour plots (3-b) indicate that re% ≥70% occurred in a limited area with an applied voltage of 50–60 v and a ph range of 4.5– 5.5. (a) (b) fig. 3. effect of applied potential and ph on copper removal efficiency: a) surface plot, b) contour plot (hold value: copper intail concentration of 15 ppm) figures (4-a and b) shows the effect of initial concentration of copper and ph on re%. a clear interaction was found between the ph and concentration of copper. in this regard, the ideal conditions differ from those found when applying the conventional one component at a time method. the corresponding contour plot (fig. 4-b) shows that re ≥75% exists within a limited region bounded by initial concentration ranging from 5 initail concentration(ppm) a p p li e d p o te n ti a l (v ) 252015105 60 50 40 30 20 > – – – – – – < 65.0 65.0 67.5 67.5 70.0 70.0 72.5 72.5 75.0 75.0 77.5 77.5 80.0 80.0 re% 0.3 4.5 6.0 04 50 60 02 7.5 04 60 07 %er )v( laitnetop deilppa hp ph a p p li e d p o te n ti a l (v ) 76543 60 50 40 30 20 > – – – – – < 45 45 50 50 55 55 60 60 65 65 70 70 re% noor r. kadhim al-khwarizmi engineering journal, vol. 20, no.3, p.p. 110 (2024) 7 ppm to 6 ppm and ph from 4.5 to 5.5). hence, applying optimisation techniques would lead to the optimum value within the limits established. (b) fig. 4. effect of ph and initial concentration on copper removal efficiency: a) surface plot, b) contour plot 3.3 optimisation and confirmation test optimisation is a crucial step used to determine the optimum conditions that yield high removal with low energy consumption in electrochemical systems. during optimisation of any system, many factors should be considered to maximise desirability function (df) and reach the intended outcome [28]. options for optimisation were none, within the limit or maximise and minimize. with df=1.0, the re objective was set to ‘maximum’. after optimisation, the outcomes are displayed in table 4. a confirmative run was carried out to verify the optimal conditions (table 5). a re of 80% was attained after electrolysis for 6 hours, starting with a copper concentration of 5 ppm and ph of 5.18 at 60 v. consequently, bbd is helpful and efficient in determining the impacts of process variables and increasing the removal efficiency to an expected level. table 4, process parameter optimisation for copper removal 𝐑𝐞𝐬𝐩𝐨𝐧𝐬𝐞 𝐆𝐨𝐚𝐥 𝐋𝐨𝐰𝐞𝐫 𝐓𝐚𝐫𝐠𝐞𝐭 𝐔𝐩𝐩𝐞𝐫 𝐖𝐞𝐢𝐠𝐡𝐭 𝐈𝐦𝐩𝐨𝐫𝐭𝐚𝐧𝐜𝐞 𝐑𝐄 (%) 𝒎𝒂𝒙𝒊𝒎𝒖𝒎 40.98 maximum 80 1 1 solution: parameters results e (volt) ph cu2+ (ppm) re (%) fit df se fit 95% ci 95% pi 60 5.18182 5 81.1334 1 1.62 (76.96, 85.31) (74.77, 87.50) table 5, confirmative run 6 12 18 50 60 70 4.5 0.3 24 0.6 4.5 5.7 70 80 %er hp )mpp(noitartnecnoc liatini initail concentration(ppm) p h 252015105 7 6 5 4 3 > – – – – – < 50 50 55 55 60 60 65 65 70 70 75 75 re% run e (volt) ph time (hr) cu2+ (ppm) re (%) initial final 1 60 5.18 6 5 1.6 80 noor r. kadhim al-khwarizmi engineering journal, vol. 20, no.3, p.p. 110 (2024) 8 the concentration of copper decreased to 0.05 ppm by refreshing the membrane with a new solvent and carrier. 4. conclusions eme was successful in removing copper from an aqueous solution at high efficiency. the studied parameters were applied voltage, ph and copper concentration. rsm was used to determine the interactions among process parameters. results revealed that the squared interaction had the most contribution to re (70.5%), followed by the linear term while two-way interaction had no significant effect. ph had the greatest influence on removal. the optimum conditions were an applied voltage of 60, ph of 5.18 and an initial copper concentration of 5 ppm. the removal efficiency of 80% was achieved during 6 hours of operation when the copper concentration was reduced to 1.6 ppm. this work confirms the vital role of eme for removing heavy metals. acknowledgment the technical personnel of the university of baghdad’s environmental engineering department is acknowledged by the authors for their invaluable help and support in this work. references [1] a. kot and j. namiesńik, “the role of speciation in analytical chemistry,” trac trends in analytical chemistry, vol. 19, no. 2–3, pp. 69–79, 2000. 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[29] w. feitknecht and p. schindler, “solubility constants of metal oxides, metal hydroxides and metal hydroxide salts in aqueous solution,” pure and applied chemistry, vol. 6, no. 2, pp. 125–206, jan. 1963, doi: 10.1351/pac196306020125. noor r. kadhim al-khwarizmi engineering journal, vol. 20, no.3, p.p. 110 (2024) 10 رف الص االستخالص الكهروكيميائي باستخدام الغشاء السائل المدعوم إلزالة النحاس من مياه االصطناعية: التحسين من خالل منهجية سطح االستجابة ****، حسن العزاوي***، علي حسين عبار **حسين فليح مجيد ،*نور راغب كاظم جامعة بغداد، بغداد، العراققسم هندسة البيئة، كلية الهندسة، *،** الهندسة الخوارزمي، جامعة بغداد، بغداد، العراق ةميائية االحيائية، كلييقسم الهندسة الك*** جامعة لنكولن، ماليزيا**** noor.jabbar2011d@coeng.uobaghdad.edu.iqالبريد االلكتروني:* altemmimi@coeng.uobaghdad.edu.iq-hussainالبريد االلكتروني:** ali.abbar@kecbu.uobaghdad.edu.iqالبريد االلكتروني:*** hazzawie2@yahoo.comالبريد االلكتروني:**** المستخلص ستخدام الخلية ( كنهج جديد تم فيه اemeدراسة إزالة النحاس من محلول مائي باستخدام استخالص الغشاء الكهربائي ) تفي هذه الدراسة، تم (.slmل صلب )شاء سائغ فضالً عنالكهروكيميائية ذات الغرفتين. تتكون الخلية من قطبين كهربائيين )كاثود الفوالذ المقاوم للصدأ وأنود الجرافيت( راسة تأثير دوتمت ( كحامل. dehpيل هكسيل( )إيث-2أوكتانول كمذيب عضوي وفوسفات مكرر )-1من غشاء بولي بروبيلين داعم مشرب بـ slmيتكون إليجاد الظروف (rsmتم تطبيق منهجية سطح االستجابة )وإزالة النحاس. فيمعلمات العملية مثل الجهد المطبق، ودرجة الحموضة، وتركيز النحاس تلك مصطلح د المطبق. يمليه الجهيإزالة النحاس فيه تأثير كبير لهذه المعلمات وكذلك التفاعالت فيما بينها. أظهرت النتائج أن الرقم الهيدروجيني ل األمثل مثلكانت الظروف األو٪ يليه المصطلح الخطي الذي يؤكد وجود تفاعل كبير بين المتغيرات. 70.5بنسبة شاركةأكبر م rsmالتفاعل التربيعي في نموذج ً فولت 60هي الجهد الكهربي المطبق 6% خالل 80لة قدرها تم تحقيق كفاءة إزا إذجزء في المليون 5، وتركيز النحاس األولي 5.18، ودرجة الحموضة ا لمستقبلي مة للتطبيق ارؤى قي ساعات من التشغيل. توضح نتائج هذا العمل نشاط استخراج الغشاء الكهربائي كوسيلة فعالة إلزالة المعادن الثقيلة التي توفر في العمليات البيئية ومعالجة المياه األخرى.لهذه الطريقة mailto:noor.jabbar2011d@coeng.uobaghdad.edu.iq mailto:hussain-altemmimi@coeng.uobaghdad.edu.iq mailto:ali.abbar@kecbu.uobaghdad.edu.iq mailto:hazzawie2@yahoo.com this is an open access article under the cc by license : al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 21, no. 3, september, (2025), pp. 55–65 violence prediction estimation in surveillance cameras using cnn with gamma correction sara ayad1*, and yarub alazzawi2 1 iraqi correctional service, ministry of justice, baghdad, iraq 2 department of mechatronics engineering, al-khwarizmi college of engineering, university of baghdad, baghdad, iraq *corresponding author’s email: saraaagh785@gmail.com (received 24 june 2024; revised 14 october 2024; accepted 10 november 2024; published 1 september 2025) https://doi.org/10.22153/kej.2025.11.004 abstract in recent years, the deployment of surveillance cameras has significantly increased to enhance security in public and private spaces. numerous businesses continue to employ individuals to monitor these cameras. however, unusual and suspicious activities in the video feeds are often overlooked due to the potential for human error. consequently, manual monitoring of security cameras can be time-consuming and inefficient. this study investigates the application of deep learning techniques, particularly convolutional neural networks (cnns) and support vector machines (svms), to predict violence in surveillance video streams. the proposed cnn model is optimised through the utilisation of gamma correction as a preprocessing step to extract essential spatial features from video frames, significantly enhancing the accuracy of violence detection. this study leverages the real-time capabilities of surveillance data by utilising the rlv dataset, which comprises a range of violent and non-violent scenarios. the cnn–svm hybrid model developed in this study achieved an impressive 99% accuracy, outperforming traditional methods and demonstrating strong spatial feature extraction capabilities. furthermore, this study addresses the challenges of real-time video surveillance by ensuring scalability and practical applicability, providing a robust solution for enhancing security measures in public and private spaces. keywords: anomaly detection; surveillance cameras; convolutional neural network (cnn); deep learning; violence detection; support vector machine. 1. introduction the use of surveillance cameras to monitor public situations is becoming increasingly common due to the growing issues in public administration, security and safety. the task of monitoring security camera footage to detect unusual behaviour, extract patterns and promptly respond may appear simple for humans. however, a person finds it difficult to simultaneously observe multiple signals due to the inherent limitations of human capabilities [1]. the process is time-consuming and costly, necessitating the involvement of people and a workplace. consequently, an automatic detection system is crucial. anomalous event identification is an essential aspect of understanding human behavioural through surveillance cameras [2]. however, detecting such events in security footage presents several challenges: (1) a large database of anomalous events is difficult to obtain due to their rarity. the learning process may be adversely affected by the lack of data. (2) an ‘anomaly’ refers to anything that deviates from a pre-established pattern (or rule). we are unable to create a model specifically designed to handle uncommon events. (3) an activity may deem normal or abnormal depending on the situation. this notion suggests that a global mailto:saraaagh785@gmail.com https://doi.org/10.22153/kej.2025.11.004 sara ayad al-khwarizmi engineering journal, vol. 21, no.3, pp. 5565 (2025) 56 anomalous event is likely to regularly occur in cases involving a gun club. although this event is common in a shooting group, the practice of ‘shooting’ is often considered unusual. however, certain conduct may be considered an anomalous practice in a particular locale and context, referred to as a local abnormal event, even if it is not inherently anomalous. varadarajan [3] characterised anomalous events as ‘actions that are performed in an unusual location, at an unusual time’. anomalous behaviour, a significant and recognised classification of learning methods, can be categorised into three approaches from a learning perspective: supervised, unsupervised and semi-supervised. specifically, single-model learning focuses solely on either normal or abnormal events for training. meanwhile, multimodel learning involves training of normal and abnormal events. the methods used in the single model learning process to distinguish abnormal events from normal ones include the following: learning the definition of normality [4-6], constructing a multidimensional model of abnormal events within the space of normal events [7-10] and learning rules that define abnormal events [11]. however, the multi-model learning strategy involves training each class either independently or in combination with other classes. this strategy is particularly effective when multiple groups of irregularities exist. in unsupervised learning, numerous clustering techniques assume that abnormal and normal events can be easily distinguished within the feature space [12-14]. additionally, the semisupervised method of detecting anomalous behaviour is not as accurate as unsupervised models and does not depend on pre-labelled data as the supervised approach does. however, anomalous behaviour detection is regarded as an unsupervised learning problem. the evolution of violence detection in video surveillance began with traditional methods that relied on handcrafted features and basic classifiers [15]. this approach was later enhanced by the integration of machine learning algorithms, which improved the classification of violent events by combining spatial and temporal features [16]. finally, deep learning models, particularly convolutional neural networks (cnns), have significantly improved the accuracy of violence detection in large-scale datasets and paved the way for highly sophisticated neural network architectures [17]. in this study, anomalous behaviour is considered a multiplescene issue under a supervised learning scheme. the classification of numerous erratic behaviours in the real world as anomalies is based on the definition of an anomalous event. in this study, we focus on the dataset [18] that contains numerous anomalous, illegal and violent behaviours captured on video in public areas. these behaviours have a serious influence on individuals and the general public. our proposed model utilised vgg16 as a cnn for feature extraction. given the nature of the video dataset, we augment the model with an svm, which can effectively handle this type of data. this methodology enhances the ability to detect irreversible damage whilst reducing the need for human labour and financial resources. moreover, this strategy is of great importance to governments and the public because it can significantly reduce emergency response times. a summary of the primary contributions of the proposed method is provided below. 1. we gather the essential data necessary to identify violence, including human bodies and their interactions, to minimise the complexity of the model’s input. this approach facilitates the development of a real-time infrastructure for crime detection. 2. we uniquely combine features derived from human interactions with temporal changes in body postures to fully utilise both information sources. 3. we recommend the effective use of a support vector machine (svm) in two-stream models designed for violent behaviour detection. this approach facilitates real-time operation whilst still maintaining accuracy. figure 1 presents a flow chart that illustrates the steps involved in implementing a video-based violence detection scheme. the first phase involves inputting a collection of movies that include violent and non-violent scenes. the second phase is key frame extraction, although not all methods utilise it. this process focuses on selecting frames that depict violent content, aiming to avoid the processing of large volumes of video, minimising the computational burden. in the third phase, the information is transformed to serve as an input for the violent behaviour detection algorithm; the type of input is based on the desired features. sara ayad al-khwarizmi engineering journal, vol. 21, no.3, pp. 5565 (2025) 57 fig. 1. basic steps in the application of an algorithm for video violence detection the remainder of this study discusses related projects that utilise different models and submodels based on the overall concept of detecting anomalous behaviour in security camera footage. section 2 presents an overview, followed by a detailed discussion of the proposed methodology in section 3. section 4 explores the findings from various experiments. section 5 concludes the study with final remarks and future project directions. 2. literature review liu et al. [19] studied various experiments, among them one by reference [20], and it is an unsupervised deep representation approach for abnormal behaviour recognition in crowded environments. this scheme relies on hybrid deep learning models and two-channel framework to learn and generate anomaly scores. the validity of the approach has been proven experimentally with training data tests and with tests in different lighting conditions. sreenu et al. [21] identified live public square cctv stream videos as a useful big data to improve safety in crowded public areas. our work is a comprehensive survey on a variety of deep learning based methods used for different crowd video analysis tasks ranging from features, action recognition, to violence detection. farroq et al. [22] attempted to detect crowd divergence behavior for disaster prevention, such as stampedes. their method presented a solution for crowd behaviour classification with a cnn on motion shaped images. the method performed better than a number of existing algorithms in terms of accuracy and employs a divergencelocalisation approach. the study also generates novel datasetsfor analyzing normal and abnormal crowd behavior in highly dense crowd environments. in high-density settings. behera et al. [23] proposed a deep learning method called pidlnet, which combines 3d convolutional features with physics-based properties, to explain crowd dynamics. varghese et al. [24] proposed an approach by integrating cognitive deep learning frameworks with a fuzzy computational model according to the sentiments, behavioural traits and visual examination. the methodology’s objective lies in the estimation and anticipation of different types of collective actions from the crowd in surveillance devices to efficiently handle the crowd. b. peixoto et al. [25] presented a new visual data-driven two-stage framework followed a data-driven approach for violent scene detection using two deep network model applied directly over raw image data. the two networks we adopt are a cnn–lstm, which involves long short-term memory, and the 3d-based cnn (c3d). instead of training the two networks separately, the authors combined c3d and cnn–lstm, and trained the model for the violence detection task jointly. this method achieved 56% accuracy on the c3d and cnn–lstm network where it was 63% for their proposed method in c3d and 61% for their proposed method in cnn–lstm model. soliman et al. [26] proposed a new model that takes a short clip as an rgb frame sequences and uses it endtoend with a deep neural network. a sequence of fully connected layers was utilised for classification. meanwhile, a pre-trained vgg-16 on imagenet was used for the spatial feature extractor, whilst an ltsm was utilised for the temporal feature extractor. reallife violence situations is a newly developed dataset consisting of 2000 videos, depicting either aggressive or peaceful scenarios. this dataset was used to improve the developed model, resulting in 88.2% overall accuracy. abdali et al. [27] introduced a real-time violence detection that uses cnn to be sara ayad al-khwarizmi engineering journal, vol. 21, no.3, pp. 5565 (2025) 58 the spatial feature extractor and ltsm to be the temporal feature extractor. the proposed model attained 98% success rate at 131 fps, meanwhile surpassing the state of the art methods. individual verification data were constructed for the three datasets and perfect performance was achieved on the movie dataset, 96.33% on hockey battle dataset and 85.71% on the violent flow dataset. for training and fine-tuning the inception-resnetv2 architecture introduced by jain et al. [28], they used a (cnn) architecture. the model was designed to learn patterns of motion in order to detect aggression. rgb video sequences were first converted to dis by temporal averaging, which maps video streams into a single image by averaging all the background and static pixels over time. these dis can enhance the motion-related characteristics efficiently while restraining discriminatory background information. the generated di’s were fed into the inceptionresnetv2 model to acquire motion features and classification for aggressive or non-aggressive behavior. the below testing result is 86.78% with the violent real-life scenario dataset, 100.89% and 92.37% with the secondary testing dataset. for the movie dataset and 93.33% for the hockey fight dataset. sernani et al. [29] proposed three models for violent behaviour detection to evaluate the degree to which harmless gestures, such as claps, small hits or high fives, are considered violent (i.e. to reduce false positive values). these models were tested on the airtlab dataset, which was designed to assess the susceptibility of algorithms to false positives. when contrasted with 2d cnns, kang et al. [30] proposed a more advanced model that integrates lstm and requires lower computational power than existing 3d-cnn-based methods. specifically, the proposed models for mobilenetv3 and efficientnet-b0 achieved tremendous success on six different violent datasets. gadelkarim et al. [31] proposed two models for the recognition and categorisation of violence, which helps in preventing daily violence. the models were developed using the following datasets: xd-violence, lad2000 and ucf-crime. similar to the xd-violence dataset, their research benefitted from transfer learning, which reduced the training period and improved accuracy. islam et al. [32] proposed an effective two-stream deep learning architecture, with the first stream incorporating a pre-trained mobilenet and the second stream comprising a separate convolutional lstm that processes frame content. they utilised three different fusion methods across three different datasets to combine the output maps from two streams. their model demonstrated excellent performance using the rwf-2000 dataset, which is the most challenging among larger datasets, achieving over a 2% increase in accuracy compared with smaller datasets. honarjoo et al. [33] proposed a convolutional-based approach with limited complexity and a series of frames with effective feature vectors. this approach successfully processed the violent waterfalls and hockey disputes. guedes et al. [34] developed a method that utilised the di approach to recognise violent activities that involve physical confrontations in video games. this method used handcrafted images processed through cnns and an svm, and it was successful when applied to the following datasets: 99.8% for movies, 97.5% for hockey games and 93.4% for crowd datasets. a summary of the papers is shown in table 1. table 1, literature survey of all the referred papers year author point of selecting the research 2019 liu et al. [19] explored hybrid deep learning methods for anomaly detection in crowded areas using unsupervised methods. 2020 sreenu et al. [21] presented live cctv streaming videos as a key big data source for security in crowded areas. 2020 farroq et al. [22] proposed cnn-based approach to detect crowd divergence behavior and prevent stampedes, outperforming other techniques. 2020 behera et al. [23] suggested pidlnet, combining 3d convolutional features with physics-based properties for crowd action prediction 2020 varghese et al. [24] developed a model combining deep learning and fuzzy logic for crowd behavior management 2021 peixoto et al. [25] presented cnn-lstm and c3d neural networks for violence detection, achieving 56% accuracy. sara ayad al-khwarizmi engineering journal, vol. 21, no.3, pp. 5565 (2025) 59 3. methodology section 3 presents an overview of the study’s methodologies, including dataset acquisition, data pre-processing techniques (such as gamma correction) and the design of the cnn model for violence prediction. moreover, this section explains the training, evaluation and performance metrics of these models, including the hybrid model (cnn–svm) for feature extraction. 3.1 datasets the real-life violence situations dataset [35] consists of 2000 videos, which takes 1000 violence videos and 1000 non-violence videos crawled from youtube. each video ranges from 50-150 frames, and the violent and non-violent videos are clips of everyday life. various images from the movies are shown in fig. 2, showing images of violence with the head of the first row and non-violence of the watershed of the second row. fig. 2. rlvs dataset samples for (a) violence and (b) non-violence. 3.2 proposed approach the block diagram provides a quick summary of all the procedures and stages involved in our methodology (fig. 3). this diagram is divided into three phases: dataset preprocessing, model training and testing and validation. the initial stage, known as preprocessing, involves gathering raw data, cleaning it and adapting it for compatibility with a machine learning model. thereafter, the models 2021 soliman et al. [26] used cnn-lstm approach for violence detection, reaching 88.2% accuracy on the reallife violence situations dataset. 2021 abdali et al. [27] developed a real-time violence detector with 98% accuracy at 131 fps 2021 jain et al. [28] utilized inception resnetv2 to transform rgb videos into dynamic images for motion recognition, achieving up to 100% accuracy. 2021 sernani et al. [29] focused on reducing false positives in violent behavior detection models 2021 kang et al. [30] proposed mobilenetv3 and efficientnet-b0 architecture with less computational power than existing 3d-cnns. 2021 gadelkarim et al. [31] proposed models for violence detection benefiting from transfer learning, achieving higher accuracy on xd-violence and ucf-crime datasets. 2021 islam et al. [32] proposed two-stream deep learning model with significant performance on rwf2000 dataset. 2021 honarjoo et al. [33] used convolutional-based approach to process violent datasets with feature vectors. 2021 guedes et al. [34] developed method using dynamic images with cnn and svm, achieving high accuracy in various datasets, including movies and crowd violence. sara ayad al-khwarizmi engineering journal, vol. 21, no.3, pp. 5565 (2025) 60 are trained for a specific task using either newly collected data or pre-trained modules. after the models have learned the fundamentals, they are tested across various applications to evaluate their performance in real-world scenarios. each procedure is discussed in detail below. fig. 3. proposed model’s block diagram 3.2.1 data pre-processing noise and missing values are unavoidable in the real world data, and ill-structured data will mislead machine learning models. pre-processingthe preprocessing is intended to bring higher quality and accuracy to the dataset by refining the information in a descending order of priority and is empirical in nature to ensure the reliability in actual career the consistency of the data is assured. when introducing the proposed architecture, the shortcomings of skeletal detection may lead to the loss of information. two pre-processing methods, histogram equalization and gamma correction, are applied to videos. concretely, the contrast-limited adaptive histogram equalisation as implemented in open cv (open cv, 2022) is applied to compute histogram equalisation and 𝛾 = 1.5 for gamma correction. performance is further enhanced by the addition of gamma correction. the results are shown in fig. 4. the gamma correction of an image 𝐼 containing pixel values in the range [0, 255] is given by the following formula: 𝐼’ = (𝐼/255)𝑌 × 255. …(1) fig. 4. a. samples from the model with gamma correction; b. samples from the model without gamma correction. 3.2.2 data partitioning this dataset is split into testing set and training set (including validation set), which are 20% and 80% of the original photos respectively. the key difference between the two sets of images is that the training dataset has known ground truth labels for all the images, and the testing images are unmarked. this is a good opportunity to evaluate the model, test it with unseen data we have collected and execute experiments following our protocols. 3.2.3 training and testing models loss, cost function, and accuracy are computed at every epoch (passing all the training samples once) for training of the designed network layers at few epochs. the cost function called ‘sparse categorical cross entropy’ is used in this situation to prevent overfitting. training is carried out on vgg-16 with a batch size of 32 in order to create a head model for a fully connected classification layer using transfer learning methods. classification report comprising the precision, f1 score and recall of the training models is created after evaluating them. validation of these models is performed on real-world violent events dataset in order to evaluate their performance. 4. analysis of results once the model is created, and the desired outcome is achieved, whether the model is producing high-quality outcomes must be determined. a confusion matrix can be used to show the trained models’ success rate to evaluate accuracy [36]. the variable value in fig. 5 can be sara ayad al-khwarizmi engineering journal, vol. 21, no.3, pp. 5565 (2025) 61 either positive or negative. the predicted data are shown in rows, and the actual data are presented in columns. true positive: the actual data are positive and predicted as positive. equation (2) can be used to determine the modelling accuracy. equation (3) states that recall indicates the proportion of correctly predicted outcomes amongst all correctly predicted outcomes. the error rate (equation (4)) indicates the percentage of the model’s predictions that are erroneous. a low error rate indicates that the model effectively operates. 𝐴𝑐𝑐𝑢𝑟𝑎𝑐𝑦=𝑇𝑃+𝑇𝑁/ 𝑇𝑃+𝑇𝑁 𝑇𝑃+𝐹𝑃+𝑇𝑁+𝐹𝑁 …(2) 𝑅𝑒𝑐𝑎𝑙𝑙=𝑇𝑃/𝑇𝑃+𝐹𝑁 … (3) 𝐸𝑟𝑟𝑜𝑟𝑟𝑎𝑡𝑒=𝐹𝑃+𝐹𝑁/𝐹𝑃+𝐹𝑁𝑇𝑃+𝐹𝑃+𝑇𝑁+𝐹𝑁 …(4) fig. 5. confusion matrix. the method is evaluated by calculating the precision, recall and f1-score to illustrate how the proposed model worked on the dataset (table 2). table 2, evaluation for classification on the rlv-crime dataset. evaluation metric (values%) precision 0.69 recall 0.50 f1-score 0.58 table 3 presents a comparison of the training and validation accuracy for both models. the cnn model with gamma correction achieves a training accuracy of 99.4% and a validation accuracy of 99.74%. meanwhile, the model without gamma correction achieves a training accuracy of 97.5% and a validation accuracy of 97.13%. these results demonstrate that gamma correction enhances the model’s overall performance, particularly in validation accuracy, which is critical for assessing how well the model generalises to new, unseen data. furthermore, these results underscore the effectiveness of gamma correction in improving the robustness and reliability of the cnn model for violence detection. table 3, the values of both train accuracy and validation accuracy for the rlv with cnn. model train accuracy validation accuracy cnn with gamma correction 99.4 % 99.74 % cnn without gamma correction 97.5 % 97.13 % the proposed method is compared with a 3d convolutional network using accuracy (acc) as the assessment parameter. table 4 compares the acc values for binary classification using our proposed method (cnn–svm) with the different models for anomaly detection. we categorise all abnormal events as ‘anomaly’ and non-anomalous data as ‘normal’. the test classifier displays the likelihood of a proper categorisation for aberrant events. thus, our model outperformed the prior techniques (table 4). table 4, acc for binary classification on the rlv-crime dataset. model acc (%) svm baseline 50.0 zhong et al. (c3d) [37] 81.08 sultani et al. (loss without constraints) [38] 74.4 our proposed model 99.7 fig. 6(a) shows the training curve for binary classification in terms of accuracy and loss value using our suggested technique with gamma correction. fig. 6(b) depicts the training curve for binary classification without gamma correction. the diagram illustrates the training curves of the cnn with an svm classifier, comparing performance with and without gamma correction. in both cases, the model shows a rapid decrease in loss and a sharp increase in accuracy during the initial epochs, indicating effective learning. however, the gamma-corrected model (fig. 6(a)) more quickly achieves lower loss and higher accuracy and stabilises at a slightly better performance level compared with the model without gamma correction (fig. 6(b)). this notion suggests that gamma correction enhances the model’s ability to learn and generalise from the training data, resulting in improved overall performance. the live detection system is applied, sara ayad al-khwarizmi engineering journal, vol. 21, no.3, pp. 5565 (2025) 62 where a streaming video, either from the source camera or the web camera, will be converted into data frames and predicted (fig. 7). (a) (b) fig. 6. training curve for binary classification of rlv dataset with 2dcnn (a) with gamma correction, (b) without gamma correction. (a) (b) fig. 7. output of the proposed method, for (a) violent, (b) nonviolence. 5. conclusion this study shows that deep learning methods, particularly cnn models combined with gamma correction, provide an effective method for identifying violent activities in surveillance footage. the model achieved a remarkable accuracy of 99% on the rlv dataset by leveraging the advantages of cnn’s spatial feature extraction and integrating svm for classification. the gamma correction step further enhances the quality of feature extraction, improving the model’s reliability under varying lighting conditions. by contrast, traditional methods that rely on handcrafted datasets and basic machine learning sara ayad al-khwarizmi engineering journal, vol. 21, no.3, pp. 5565 (2025) 63 techniques exhibit low performance and limited generalisability. the model’s ability to handle realtime data and its computational cost efficiency make it a promising solution for real-world applications. future research may explore additional datasets from various video sources to further enhance the model’s generalisability. another potential direction involves integrating more advanced deep learning models, such as resnet or lstm, to improve the detection of spatial and temporal features. references [1] geetha, r., gunanandhini, s., srikanth, g. u., & sujatha, v. 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( 2025) 55-65، صفحة 3، العدد21مجلة الخوارزمي الهندسية المجلدسارة اياد ربيع 65 مع تصحيح جاما cnn تقدير التنبؤ بالعنف في كاميرات المراقبة باستخدام 2يعرب عمر ناجي ، *1سارة اياد ربيع العراق بغداد، اإلصالح العراقية، وزارة العدل، ةدائر 1 بغداد، بغداد، العراق الخوارزمي، جامعةقسم هندسة الميكاترونيكس، كلية الهندسة 2 saraaagh785@gmail.com: البريد االلكتروني* المستخلص الشركات تستأجر الكثير منمن األماكن العامة والخاصة. ال تزال في نشر كاميرات المراقبة لتعزيز األمن في كل كبيراً شهدت السنوات األخيرة ارتفاًعا اللمرشخًصا فمن األحيان، بعض في بشري لحدوث خطأ نظًرا ولكن الكاميرات، في رااقبة الغريبة األحداث بعض عن المستأجر الفرد يتغاضى أن جح تطبيق تقنيات التعلم العميق، أبحث في في هذه الدراسة. المراقبة تتبع كاميراتموجزات الفيديو. وبالتالي قد يكون من غير المجدي قضاء الوقت والجهد في ، للتنبؤ بالعنف في تدفقات فيديو المراقبة. من خالل استخدام تصحيح جاما (svms) وآالت الدعم المتجهة (cnns) وخاصة الشبكات العصبية التالفيفية نموذجالمعالجة للكخطوة تحسين تم اكتشاف cnn مسبقة، الفيديو، مما يعزز بشكل كبير دقة المكانية األساسية من إطارات السمات المقترح الستخراج ، والتي تشمل مجموعة من السيناريوهات العنيفة rlv العنف. تستفيد الدراسة من قدرات الوقت الفعلي لبيانات المراقبة، مع التركيز على مجموعة بيانات العنيفة. نموذجووغير بنسبة cnn-svm حقق مذهلة دقة البحث هذا في تطويره تم الذي قدرات 99الهجين ومظهًرا التقليدية الطرق على متفوقًا ،٪ القوية. المكانية السمات عناستخراج والتطبيق فضالً التوسع قابلية من خالل ضمان الفعلي الوقت في بالفيديو المراقبة تحديات البحث هذا يتناول ذلك، .قويًا لتعزيز تدابير األمن في األماكن العامة والخاصةالعملي، مما يوفر حالً mailto:saraaagh785@gmail.com this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 19, no. 1, march, (2023) p. p. 1423 study of the effect of magnetic abrasive finishing on the material removal of aa1100 aluminum alloy mariam majeed* ali h. khadum** salah al-zubaidi*** *,**,***department of automated manufacturing engineering/ al-khwarizmi college of engineering/ university of baghdad/ iraq *email: mageedmarim@gmail.com **email: kadhumali59@yahoo.com ***email: salah.salman@kecbu.uobaghdad.edu.iq (2022 bernovem 14 2022; accepted uryafebr 7received ) https://doi.org/10.22153/kej.2023.11.001 abstract this study evaluates the performance of magnetic abrasive finishing (maf) of aluminum alloy in terms of achieving materials removal (mr). a vertical milling machine is used to perform the finishing process using a developed maf unit that consists of an inductor made out of a 150 mm long and 20 mm diameter iron core wound with 1500 turns and 0.5 mm copper wire. the commutator and magnetic pole are attached at the top and bottom of the inductor, respectively. the required current is supplied using a dc power supply. the south pole workpiece is a 100×50×3 mm3 plate of aa 1100 aluminum alloy, whereas the magnetic pole represented the north pole. pole rotational speed, applied current, and abrasive finishing time was selected as input parameters of the maf with three-level of (270, 600. 930 rpm; 0.5, 1, 1.5 amp; 6,9,12 min). the l9 orthogonal array of the taguchi method was utilized to examine the impact of each independent input. the obtained results clarify that applied current was the most effective factor in terms of its contribution (63.16%) in the produced mr, followed by time finishing and rotational speed. keywords: magnetic abrasive finishing, aluminum alloys, material removal, anova. 1. introduction a remarkable need for machined components with high surface quality in high-tech industries has steadily increased for new finishing methods. however, it is hard to machine complex parts with defect-free and precise dimensional finishing by normal grinding and polishing operations. to reduce surface imperfections, appropriate machining conditions with minimum cutting forces are required [1]. magnetic abrasive finishing (maf) is one of the important super-finishing methods that is capable to generate fine surface finish for various shapes and geometries at the scale of nanometers without causing surface damage, particularly for miniature and complex parts [2]. external and internal cylindrical shapes, as well as flat surfaces, can be finished by the maf process which opens the way for many high-tech parts with different sizes and geometries to acquire high surface finishing and dimensional accuracy [3,4,5]. figure 1 shows the principal workflow of the maf process in a simple form. the setup illustrates that the maf consists of a rotatable magnetic pole that is positioned at a predetermined gap and attracts the magneticabrasive particles (maps), to form a flexible magnetic brush (fmab) that plays as a multiplecutting tool to finish the well-clamped workpiece (w.p). the workpiece-magnetic pole represents the s-n poles pair. the maps consist of ferromagnetic materials which are usually iron powder while the abrasive particle is often hard carbides, oxides, or nitrides. maf in nature is a material removal process which means certain forces are mailto:mageedmarim@gmail.com mailto:kadhumali59@yahoo.com mailto:salah.salman@kecbu.uobaghdad.edu.iq https://doi.org/10.22153/kej.2023.11.001 mariam majeed al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 1423 (2023) 15 responsible to cut material in the chips form. the fmab applies two types of forces namely; a normal force for micro-indentation due to pressing the action and a tangential force for material removal by relative motion between w.p and fmab [6]. fig .1. principle of magnetic abrasive finishing process [6]. because of its invention, great efforts have been made to improve the performance of maf. for instance, geeng-wei changet et al.[7] illustrates that the fundamentals of the maf process as a finishing operation are investigated by using iron-sic as magnetic abrasive particles with lubricant to produce unbounded maps. rotational speed, abrasive volume, and time are studied by wang and hu [8] as mafindependent inputs during the finishing of tubes made of different metallic alloys. the examination illustrated that the removal of material and surface finish are significantly influenced by increasing the rotational speed. shrikant thote et al. [9] investigate the impact of iron powder amount, abrasive mesh size, and utilized current when the maf finishing of stainless steel part. both surface finish and material removal are improved by increasing the level of those controllable variables. joshi, r et al.[10] conduct a study to examine the response of three materials aisi 304 stainless steel, copper, and cast iron to the magnetic abrasive finishing process. the best findings are recorded by the cooper alloy through achieving better material removal and fine surface finishing where the latter was reduced from 0.257 µm to 0.075 µm. a 3% oil is added to the abrasive particles of sic and al2o3 mixture by satsang, prem s et al.[11] who study the additives' effects as well as the working gap and time on the material removal. because, different mesh sizes are used: 100, 200, and 400. it was revealed that both mesh size and time have a strong effect on material removal. for example, maximum material removal is achieved by the sic-100 compared with that obtained by al2o3-400. the performance of magnetic poles shown in figure 2 was evaluated by marwa khalil et al et al. [12] based on the produced surface finish and material removal. other parameters are also involved in the investigation like gap, current, time, speeds of the workpiece, and pole. the findings show that workpiece speed was the more influential by achieving 24% compared with other factors. fig. 2. poles geometry [12]. mariam majeed al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 1423 (2023) 16 a maf process is combined with electrolysis (e) by m. r. muhamad et al. [13] which results in the development of the emaf process to finish the aa 6063 internal surface tube. in the beginning, the electrolysis produces a thin layer of al2o3 to facilitate the removal of some surface morphology. later on, this layer was eliminated by maf to complete the finishing process. the findings proved the effectiveness of developed emaf by reducing finishing time and cutting forces and recommended low exposure time for electrolysis to avoid the formation thick layer of al2o3 that reduces the surface quality. another study was performed by babar, a. et al. [14] to measure the influence of degrees of time, speed, mesh size, and amount of maps during the finishing of flat copper alloy. based on anova findings, a significant role is played by speed and time to produce minimum ra and maximum material removal. the generated temperature during the maf process of cuzn28 brass alloy was evaluated by ali h. kadhum [15]. the studied parameters are speed, current, and working gap. the distribution of produced temperature during material removal from the finishing region is measured based on experimental and numerical simulation with an overall difference of less than 9%. adhesive abrasive particles are adopted as maps by singh, b et al. [16] during the inner surface finishing of an aluminum tube. the authors find a remarkable effect of rotational speed on the obtained material removal and surface roughness where they record a maximum improvement at optimum parameters of 2.74 mg/min and 81.49 %, respectively kumar, v et al. [17] processed homogeneous mixture maps consisting of iron powder and diamond particles to evaluate its performance in terms of material removal during the finishing of the circular stainless steel section. it can be concluded that as the diamond amount increases, the material removal also increases. the results of the maf process using different pole geometries shown in figure 3 are discussed by mahmoud abdallah et al. [18]. they found better maf performance when using low-angle poles where the roughness and material removal are improved at high speed and medium time and gap. fig. 3. pyramid pole with different angles [18]. huijun xie and yanhua zou [19] applied an alternating magnetic field instead to enhance the surface finish of 304 stainless steel alloy. they used alternating current with sine and square waveforms. the fluctuation behavior of the magnetic clusters in two alternating magnetic fields is noticed and investigated. the authors deduced from the analysis faster fluctuation in the magnetic cluster when utilizing square wave and small magnetic particles. there was a large variety in fluctuation rate in the magnetic cluster between the two waveforms. the surface roughness of the stainless steel plate improves from 328 nm ra to 14 nm ra in 40 minutes, according to the findings. yulong zhang and yanhua zou [20] adopted an approach to illustrate the influence of correcting the work part surface. the adjusting the maf parameters like feed speed on various locations based on the profile of the initial unmachined surface. a theoretical examination of this method was performed, as well as the application of this approach to the larger areas. the geometrical accuracy of the work part surface can be efficiently controlled by correctly adjusting the feed speed, according to a series of studies on an aluminum plate (a5052). the experimental findings indicated that within the processed area of 30 x10 mm, the large difference of the workpiece surface finish was lowered from 4.81 µm to 2.65 µm. material removal refers to the material amount that has to be removed during any machining process and can be measured based on volumetric material removal or weight difference before and post the cutting process. material removal is mariam majeed al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 1423 (2023) 17 between the two important indexes that are usually taken into account during the assessment of maf performance in addition to the surface finishing. therefore, the current study aims to evaluate the performance of maf in terms of material removal when finishing aa1100 flat aluminum alloy. 2. materials and methods to implement the magnetic abrasive finishing process, a milling machine was utilized to perform the finishing of aa1100 aluminum alloy. the maf unit shown in figure 4 incorporates a 150 mm length and 20 mm diameter iron core winded with 1500 turns of 0.5 mm copper wire to make the inductor. the top and bottom of the inductor are attached by the commutator and magnetic pole respectively. the power supply that was used provides a dc current. 100×50×3 mm3 plate of aa 1100 aluminum alloy was used as a south pole workpiece while the north pole is represented by the magnetic pole. the compositional analysis of aluminum alloy being used is depicted in table. fig. 4. maf unit assembled on milling machine. table 1, the compositional analysis of aa 1100 alloy. element zn mn cu be si, fe al standard 0.1(maximum) 0.05 (maximum) 0.05-0.2 0.0008 (maximum) 0.95 (maximum) balance real 0.0339 0.0146 0.0596 <0.001 0.361 balance powder of iron-tungsten carbide mixture was used as magnetic abrasive particles (maps). the amount of wc in grams is twice the iron powder respective mesh size of 320 and 200. figure 5a shows the assembled magnetic pole while a flexible magnetic brush (fmab) is depicted in figure 5b. fig. 5. magnetic iron poles, a. pole before applying a magnetic field, and b. pole with the created magnetic brush. ba mariam majeed al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 1423 (2023) 18 regarding the maf parameters, rotational speed, dc-current, and maf time are chosen as variable parameters with three levels while other parameters are kept unchanged as illustrated by tables 1 and 2, respectively. table 2, selected maf parameters and corresponding levels no. maf parameters unit parameter symbol level 1 level 2 level 3 1 rotational speed r.p.m a 270 rpm 600 rpm 930 rpm 2 dc current ampere b 0.5 amp. 1amp. 1.5 amp. 3 finishing time minute c 6 min 9 min 12 min table 3, fixed parameters no parameters value 1 material of work piece al dimensions of workpiece 50 х 100 х 3 mm 2 ambient temperature 20 cº 3 direction of rotation ccw 4 abrasive particles fe-wc mixed powder 5 fe mesh size # 320 6 wc mesh size # 200 7 applied voltage 220 v 8 gap 1 mm 10 frequency 50 hz taguchi method for the design of experiment is applied with the l9 orthogonal array using minitab 17. table 4 shows the l9 array with coded and actual factors. it consists of nine experimental runs with three variable parameters at different three levels each. the low, medium and high levels of rotational speed, current, and time are 270, 600, and 900 rpm; 0.5, 1, 1.5 amp; 6, 9, and 12 minutes respectively. the output response that was measured and evaluated in this study is material removal in mg. figure 6 shows the sensitive balance that is used to measure the weight of the specimen before and after maf to calculate the net difference in weight for each run referring to the material removal (δmr) of that specimen. at the same time, the material removal improvement rate (mrir) is calculated by using equation 1: 𝑀𝑅𝐼𝑅 = initial mr−final mr initial mr ∗ 100% … (1) table 4, coded and real maf parameter of l9 array run no. rotational speed (rpm) dc-current (amp.) finishing time (min.) rotational speed (rpm) dc-current (amp.) finishing time (min.) 1 1 1 1 270 0.5 6 2 1 2 2 270 1 9 3 1 3 3 270 1.5 12 4 2 1 2 600 0.5 9 5 2 2 3 600 1 12 6 2 3 1 600 1.5 6 7 3 1 3 930 0.5 12 8 3 2 1 930 1 6 9 3 3 2 930 1.5 9 mariam majeed al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 1423 (2023) 19 fig. 6. sensitive balance device (model type: sartorius readability: 0.1 mg). 3. results and discussions the material removal is measured and material removal rates are calculated and both values are tabulated as in table 5. the maximum and minimum values are also involved within the same table. table 5, average improvement of material removal (δmr). run no. rotational speed (rpm) dc current (amp.) finishing time (min.) δmr(g) mrir 1 270 0.5 6 0.0018 0.004 2 270 1 9 0.0013 0.003 3 270 1.5 12 0.0067 0.016 4 600 0.5 9 0.0029 0.007 5 600 1 12 0.0047 0.011 6 600 1.5 6 0.0072 0.017 7 930 0.5 12 0.0035 0.009 8 930 1 6 0.0057 0.014 9 930 1.5 9 0.0062 0.015 max 0.0072 0.017 min 0.0013 0.003 3.1. statistical analysis of the results the first step of the discussion is to analyze the achieved results statistically with the aid of anova as depicted in table 6. the anova results clarify the significance of the model with a 0.05 value. also, applied dc-current achieves a low p-value of 0.016 which refers to its significance over the other two parameters. the speed and time are not significant. the current also records the highest contribution percentage of 63.16 % followed by time and speed. table 6, analysis of variance of material removal (mr). source degree of freedom adjusted ss adjusted ms fvalue pvalue significant parameter percentage of contribution% regression 3 0.000028 0.000009 5.16 0.05 significant a rotational speed 1 0.000005 0.000005 2.61 0.167 n0t significant 13.16% b dc current 1 0.000024 0.000024 12.87 0.016 significant 63.16% c finishing time 1 0.000007 0.000003 0.66 0.551 n0t significant 18.42 error 5 0.000001 2 0.000002 _ _ _ 5.62% mariam majeed al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 1423 (2023) 20 total 8 0.000038 _ _ _ _ 100% 3.2 regression model for the maf process a linear regression model is constructed to correlate the material removal with rotation speed, current, and time. equation 2 shows the developed model that was used to predict the material removal where each parameter has its coefficient in addition to the model constant. if each set of finishing conditions shown in table 5 is substituted the a, b, and c factors of the regression model, table 7 will be constructed, which shows the predicted material removal besides the experimental values. δmr = -0.00119 + 0.000003 a + 0.00397 b + 0.000011 c …(2) table 7, predicted and experimental δmr with average % error. run no. rotational speed (rpm) dc-current (amp.) finishing time (min.) δmr(g) predicted δmr 1 270 0.5 6 0.0018 0.001671 2 270 1 9 0.0013 0.003689 3 270 1.5 12 0.0067 0.005707 4 600 0.5 9 0.0029 0.002694 5 600 1 12 0.0047 0.004712 6 600 1.5 6 0.0072 0.006631 7 930 0.5 12 0.0035 0.003717 8 930 1 6 0.0057 0.005636 9 930 1.5 9 0.0062 0.007654 if both experimental and predicted material removal is plotted against experimental runs, figure 7 is produced. as can be seen from figure 7, some points are near each other while other points sit at a distance from each other. this can be ascribed to the fact that the linear model can effectively represent linear problems but, material removal processes are non-linear problems in most. therefore, the model shows some difference between actual and predicted values. fig. 7. experimental and predicted δmr. 3.3. effect of magnetic abrasion parameters on the performance of maf. the second step of the discussion is to analyze the magnetic abrasive parameters of the achieved material removal. to perform this analysis and discussion, the main plot effect of means depicted in figure 8 is introduced here to support our discussion. a statistical analysis that is presented has given a good view of the degree of influence of each parameter on the achieved material 0 0.001 0.002 0.003 0.004 0.005 0.006 0.007 0.008 0.009 0 5 10 δ m r no.exp experimental δmr predicted δmr mariam majeed al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 1423 (2023) 21 removal. the main effect plot of means shows the relationship between the mean of means for material removal (δmr) versus the three levels of rotational speed, current, and time. thus, it is a beneficial graph that enables us to show how material removal is affected by maf parameters. the plot reveals that material removal is hugely influenced by the increasing current from low to high levels including medium ones. the average values of δmr against current according to what the main plot shows, is ranging approximately from 0.00275 to 0.00675. the corresponding range of δmr versus time is lower and that for rotational speed is the lowest. this effect is consistent with what anova has gone with, in terms of impact extent and percentage of contribution where current achieves the highest values followed by rotational speed and time. fig. 8. plots of parameters main effect verses mean δmr. to explain why current was the most effective factor, the fact has been recalled here concerned with the intensity of generated magnetic field where this field is directly correlating to the applied current. in other words, as the current increases, the magnetic flux intensity increases also and this increment is reflected positively in the amount of rigidity for the generated flexible magnetic brush (fmab) due to that applied current. the more rigid fmab creates many relatively deep penetrated micro-indentations inside the surface. this action refers to the applied normal forces which are integrated with the tangential force, exerted by the relative motion between rotatable fmab and the specimen being finished to perform the whole material removal process. to sum up, a rigid and strong multiple cutting tool (fmab) has been generated at a high current level (1.5 amp.) that introduces numerous microindentations and introduced to the surface being finished by the action of induced normal forces applied by fmab to promote more materials removal with the assistant of tangential forces comes from the rotatable magnetic pole to perform maf process completely. 4. conclusions the obtained findings based on the analysis and discussion have enabled us to conclude the following points: 1. the aa 1100 aluminum alloy has been successfully finished by the magnetic abrasive finishing process. 2. the applied current has been the most significant factor and contributor with 63.16% followed by time and speed with percentage contributions of 18.42% and 13.16%, respectively. 3. maximum material removal has been recorded at low speed (270 rpm), high current (1.5 amp.), and high finishing time (12 min.). 5. references [1] d. k. singh, v. k. jain and v. raghuram” on the performance analysis of flexible magnetic mariam majeed al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 1423 (2023) 22 abrasive brush” mach. sci. technol., vol. 9, no. 4, pp. 601-619, 2005. 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[11] wu, j.; zou, y." study on mechanism of magnetic abrasive finishing process using low-frequency alternating magnetic field" international conference on electromechanical control technology and transportation (icectt 2015). 2015, 395, 985–989. [12] marwa k. qate’a, ali.h. kadhum, faiz f. mustafa "the influence of the magnetic abrasive finishing system for cylinder surface on the surface roughness and mrr" alkhwarizmi engineering journal, vol. 11, no.3, page 1-10,2015. [13] m. r. muhamad, y. zou, and h. sugiyama"investigation of the finishing characteristics in an internal tube finishing process by magnetic abrasive finishing combined with electrolysis" trans. inst. met. finish., vol. 94, no. 3, pp. 159–165, 2016, doi: 10.1080/00202967.2016.1162400. [14] a. babbar, p. singh, and h. s. farwaha"regression model and optimization of magnetic abrasive finishing of flat brass plate" indian j. sci. technol., vol. 10, no. 31, pp. 1–7, 2017. [15] d.a.h. kadhum, “comparative analysis on numerical modelling and experiments of the cutting temperature in magnetic abrasive finishing process”, the iraqi journal for mechanical and materials engineering, vol. 19, no. 1, pp. 1–13, 2019. doi: 10.32852/iqjfmme. v19i1.260. [16] p. singh, l. singh, and a. kaushik"parametric optimization of magnetic abrasive finishing using adhesive magnetic abrasive particles" int. j. surf. eng. interdiscip. mater. sci., vol. 7, no. 2, pp. 34– 47, 2019. [17] v. kumar, r. sharma, k. dhakar, y. k. singla, and k. verma"experimental evaluation of magnetic abrasive finishing process with diamond abrasive" int. j. mater. prod. technol., vol. 58, no. 1, pp. 55–70, 2019. [18] mahmmoud abdallha, salah al-zubaidi and ali h. kadhum "effect of magnetic abrasive finishing process on the surface roughness of cuzn28 with new pole geometry" journal of mechanical engineering research and developments, vol. 43, no. 4, pp256264,2020. [19] xie, h.; zou, y. investigation on finishing characteristics of magnetic abrasive finishing process using an alternating magnetic field. machines 2020, 8, 75. https://doi.org/10.3390/machines8040075. [20] zhang, y.; zou, y. study on corrective abrasive finishing for workpiece surface by using magnetic abrasive finishing processes. machines 2022, 10, 98. https://doi.org/10.3390/machines10020098. https://doi.org/10.3390/machines8040075 https://doi.org/10.3390/machines10020098 (2023) 14-23، صفحة 1، العدد19مجلدمجلة الخوارزمي الهندسية ال مريم مجيد 23 يكةلسب المعدنالكاشطة المغناطيسية على إزالة االنهاء السطحي بالجسيماتدراسة تأثير aa1100 األلومنيوم ***صالح الزبيدي** كاظمعلي حسن * مريم مجيد العراق /جامعة بغداد /كلية الهندسة الخوارزمي /المؤتمتقسم هندسة التصنيع *،**،*** mageedmarim@gmail.com:البريد االلكتروني* kadhumali59@yahoo.com**البريد االلكتروني: salah.salman@kecbu.uobag baghdad.edu.iq***البريد االلكتروني: الخالصة تم استخدام (mr). نالمعدمن حيث إزالة aa1100 األلومنيوم لسبيكة الكاشطة المغناطيسية بالجسيماتأداء الصقل الى تقييم هذه الدراسة تهدف وملفوف بمم 20مم وقطر 150حديد بطول المصنوع من مستحثمطورة تتكون من maf عمودية إلجراء عملية التشطيب باستخدام وحدة ماكنة تفريز لتيار المطلوب ا تجهيزعلى التوالي. تم المستحث،مم. تم توصيل المبدل والقطب المغناطيسي في أعلى وأسفل 0.5 سلك نحاسي بقطر لفة من 1500 القطب مثل، بينما 3م م 3× 50× 100 ابعادها المنيوم عن صفيحة واليت كانت عبارةقطعة عمل القطب الجنوبي مثلتباستخدام مصدر طاقة تيار مستمر. جسيمات المغناطيسية االنهاء بال لعمليةmaf إدخال كمتغيراتووقت االنتهاء المستمرالمغناطيسي القطب الشمالي. تم اختيار سرعة الدوران والتيار مع المصفوفة taguchi دقيقة(. تم استخدام طريقة 6.9,12أمبير؛ 1.5، 1، 0.5دورة في الدقيقة؛ 930. 600، 270مستويات لكل منها ) بثالث هطالكاش بـ اهمتهلية من حيث مسكان العامل األكثر فاع وضحت النتائج المتحصل عليها أن التيار المطبقأمستقلة. المدخالت التأثير كل لدراسة l9 المتعامدة .الوقت وسرعة الدوران تاله المنتج،المعدن أزاله ٪( في63.16) mailto:mageedmarim@gmail.com*البريد mailto:mageedmarim@gmail.com*البريد mailto:kadhumali59@yahoo.com regarding the maf parameters, rotational speed, dc-current, and maf time are chosen as variable parameters with three levels while other parameters are kept unchanged as illustrated by tables 1 and 2, respectively. table 2, selected maf parameters and corresponding levels table 3, fixed parameters taguchi method for the design of experiment is applied with the l9 orthogonal array using minitab 17. table 4 shows the l9 array with coded and actual factors. it consists of nine experimental runs with three variable parameters at different three lev... 𝑀𝑅𝐼𝑅=,initial mr−final mr-initial mr.∗ 100% … (1) table 4, coded and real maf parameter of l9 array fig. 6. sensitive balance device (model type: sartorius readability: 0.1 mg). table 5, average improvement of material removal (δmr). table 6, analysis of variance of material removal (mr). predicted and experimental δmr with average % error. fig. 7. experimental and predicted δmr. fig. 8. plots of parameters main effect verses mean δmr. <4d6963726f736f667420576f7264202d20ddc7d8e3c920cdd1cfc7e420e6cf20c7cde3cf20d1cde3e433382d3530> this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 18, no. 1, marh, (2022) p. p. 3850 developing an automated vision system for maintaing social distancing to cure the pandemic fatima hardan* ahmed r. j. almusawi** *,**department of mechatronics engineering/ al-khwarizmi college of engineering/ university of baghdad *email: fatima.ibrahim1402@kecbu.uobaghdad.edu.iq **email: ahmedalmusawi@kecbu.uobaghdad.edu.iq (received 2 february 2022; accepted 17 march 2022) https://doi.org/10.22153/kej.2022.03.002 abstract the world is currently facing a medical crisis. the epidemic has affected millions of people around the world since its appearance. this situation needs an urgent solution. most countries have used different solutions to stop the spread of the epidemic. the world health organization has imposed some rules that people should adhere. the rules are such, wearing masks, quarantining infected people and social distancing. social distancing is one of the most important solutions that have given good results to confront the emerging virus. several systems have been developed that use artificial intelligence and deep learning to track social distancing. in this study, a system based on deep learning has been proposed. the system includes monitoring and detecting people besides measuring the social distance between them. the proposed system consists of two parts: (1) detecting the faces of people using the viola-jones algorithm. the cascade classifiers were trained. the cascade classifiers used in the algorithm with feature descriptors to detect side faces and wear masks. hence, training is dominant for detection. (2) measurement of the euclidean distance between the centers of the rectangles of the people who were revealed in the first part. the distance between individuals' is measured to check how well they adhere to social distancing. the results revealed that the proposed system can perform well in applying images to track the distance between people. keywords: face detection , social distancing, viola-jones. 1. introduction deep learning represents a renewed and developing field of research that deals with finding theories and algorithms that allow the machine to learn on its own by simulating the work of neurons in the human brain, so it is part of machine learning. most researchers in the field of deep learning focus on finding new algorithms and developing old ones by analyzing a huge data set [1]. deep learning has made wide, rapid and effective progress in many areas, including face detection and recognition, speech recognition, and computer vision. the machine is taught from big data using various designs of deep learning networks such as recurrent networks (rnns) and convolutional neural networks (cnns). an image can be described on the basis of the degree of brightness in each pixel and expressed as a vector or by expression based on the sum of the edges and regions that make up the image[2]. one of the goals of deep learning is to replace human-defined features of machine learning with features that are extracted by efficient featureextracting algorithms and are produced by the machine itself[3]. due to the development in deep learning and its use in various aspects of life, researchers have tended to exploit computer vision and image processing. computer vision fatima hardan al-khwarizmi engineering journal, vol. 18, no. 1, p.p. 3850 (2022) 39 and image processing are the processes of converting images into digital information and changing the nature of images to make them more convenient and simpler to understand by the machine and also improving the graphic information and its interpretation of the human being[4]. that is in, observing the social distancing between people and the extent of their commitment to it. considering the spread of epidemics and diseases, scientists and researchers are trying to find appropriate solutions to stop the spread of these diseases. they found that social distancing is one of these important solutions that prove its effectiveness in reducing the spread of epidemics every time it is used. the main purpose of social distancing and imposing a safe distance between people must be adhered to with the various ways in which it is implemented[5]. a distance of 2 m has been determined as a safe distance in most countries, and this has been determined by governments and health authorities, and it is considered a mandatory measure at the time of epidemics [6]. the other form of social distancing is imposing a ban and keeping people in their homes, as well as quarantining the injured [7]. in this paper, a system based on deep learning is proposed to automatically detect people's faces and monitor the social distance. in the article, the first part of the proposed system was clarified, which is face detection, and its algorithm. the viola-jones algorithm, is one of the deep learning algorithms. the algorithm was used with training using one of the feature descriptors to improve classification performance. second, the distance between the people who were discovered was measured to determine their commitment to social distancing. the model showed good performance through the experimental results. fig. 1. a. social distance must be between people [8]. b. monitor social distancing [6]. 2. related work in this part, some of the previous systems that were proposed to monitor social distancing are briefly presented. the systems measure the distance between people, and alert violators of the safe distance. with the spread of epidemics, researchers began to work to find solutions that control the spread of the epidemic widely around the world. social distancing has been suggested as one of the important solutions in such circumstances, which proves its effectiveness every time it is used. economically speaking, social distancing is a strict measure to flatten the curve against diseases infectious. many countries have turned into this technology to be exploited in monitoring and implementing social distancing. detecting objects largely contributes to such a situation. many researchers have studied the situation to discover different types of objects that help in the scenario [9-12]. a well-established field of research is human discovery. recent developments in this field have contributed to a greater demand for intelligent systems to monitor extraordinary human activities [13, 14]. despite the difficulties faced by human detection such as blurred video clips, various articulated poses, background complexities and limited machine learning capabilities, it is an interesting area, and the detection performance can be enhanced by existing knowledge [9]. narinder et.al. proposed a system based on deep learning to automatically a b fatima hardan al-khwarizmi engineering journal, vol. 18, no. 1, p.p. 3850 (2022) 40 monitor the distance between people using video surveillance [10,11]. people were separated from the background using yolo v3 algorithm [15] with deep sorting technology, and with the assistance of surrounding boxes, the detected people are tracked. adina rahim et. al. [16] have proposed a system for monitoring social distancing in lowlight environments and at night. it is based on yolo v4 training [17] on the exdarknet dataset to monitor social distancing with the use of a raft camera. the camera is fixed to monitor people at the distance installed by the camera and the resulting distance is shown in real world units. as for the scientist shashi yadav[18] he proposed a system based on computer vision to detect people in real time through automatic monitoring in public places. the researcher implemented his proposed system on raspberry pi 4 to monitor the activity and detect if there is an overdose through the camera. engineering techniques and deep learning algorithms have been combined to build a powerful system that detects, tracks, and checks, as it sends an alert if the distance is violated. in another proposal, researchers mahdi rezaei and mohasen azarmi [6] presented a system that uses cctv surveillance cameras with the development of a deep neural network to automatically detect people and calculate the distance between them in crowded places. the human detector was used deepsocial and this system was developed to be able to work in different conditions such as changing lighting, obstruction, shadows and partial vision. afiq harith et. al. [19] introduced a system that monitors the social distance between individuals and detects people using the ssd[20] object tracking system, as well as the opencv[21] library for image processing. installed pixel values are chosen and after calculating the distance between people, they are compared with these installed values to see if this distance has been exceeded or not. krisha and others [22] suggested another system that helps in detecting social distancing between people and detecting violations. the system uses a deep learning algorithm yolo v4 to detect people, after identifying them , the distance between them is measured using the coordinates through the principles of optics. as for yew cheong hou et. al.[23] they proposed a system that uses the yolo v3 deep learning algorithm, through which people are detected using the open source to detect pretrained objects. as for the distance between people, it is calculated from the 2d plane by converting the video frame into a top-to-bottom view. after estimating the distance between them, a red frame is placed around the people who do not comply with the permissible distance. several research studies have been conducted to monitor social distancing and provide the best effective solution for social distance monitoring. that is by using multiple algorithms of deep learning algorithms and integrating them with other methods as discussed previously. in this study, one of the deep learning algorithms " viola-jones algorithm" was used to detect and identify people so that the social distance between them is monitored. this algorithm has not been mentioned before in monitoring social distance between people. therefore, this work focuses on the use of the viola-jones method to monitor the distance between people and how it has been trained to detect faces in different situations. 3. background of deep learning models in the process of monitoring the distance between people, the presence of these individuals in the photo or video clip is first detected. this is done through machine learning, which is represented by deep learning algorithms with computer vision or image processing. one of these algorithms are r-cnn and its version (rcnn[24] , fast r-cnn [25], faster r-cnn [26]). the working principle of r-cnn is to suggest the area, which is represented by the surrounding boxes [16]. the sliding window method was utilized by the classifier and it is taken by taking a slice of the image, therefor, this is the principle of the oldest algorithm from rcnn, which is the deformable fragments algorithm (dpm) [27].as for the newer algorithm currently, it is yolo algorithm, which was proposed in 2016 by joseph and others [28] and it detects objects in real time, and its other version is worked by the same principle. these versions are yolo v2[29], yolo v3[15] and in 2020 yolo v4 proposal [17]. the general structure of the detectors for organisms consists of 3 parts: the spine, the neck and the last part is the head [17], as shown in fig. 2. as for the main tasks of the detectors , they are represented by three tasks, which are: 1. extracting traits 2. choosing important traits 3. classify the goals and enclose the desired goal in a square. fatima hardan al-khwarizmi engineering journal, vol. 18, no. 1, p.p. 3850 (2022) 41 fig. 2. general architecture of object detectors. 4. methodology this research aims to propose a system for measuring the level of threat or risk in public areas by monitoring social distancing between people. the proposed system is based on deep learning, where the presence of people in a particular area is first detected. second, the system measures the distance between the discovered individuals to determine whether they respect and apply the rule of social distancing. to carry out the training process, we collected data that encompass faces and others that do not incorporate faces. pictures that encompass faces are front and side, as well as some that wear masks. as for the pictures that do not contain faces used in training, the number is approximately double the number of pictures containing faces. the system design consists of two parts that correctly handle the input images. the first part is face detection. the viola-jones algorithm was used to detect faces in the captured images and was trained to detect side faces as well. the second part measures the distance between the people discovered in the first part. where the euclidean distance between them is measured and compared with the proven distance to determine whether there is a violation of the safe distance or not. the flowchart in fig. 3 illustrates the flow of the proposed system. fatima hardan al-khwarizmi engineering journal, vol. 18, no. 1, p.p. 3850 (2022) 42 fig. 3. flowchart of the system. 4.1. face detection face detection is an essential part of the designed system. this stage is the first stage in the system before measuring the distance. in this part we need an effective detector that can detect masked faces. furthermore, that we need to localize complex cases such as side faces, hence, we relied on a deep learning algorithm that is pretrained to detect faces. it was trained to detect side faces and mask wearers, this algorithm is violajones. violajonse algorithm in 2001 the viola-jones method was proposed by researchers paul viola and michael jones for target discovery. the main objective for which this method was proposed is to detect faces and it can be trained to detect different things. despite the acceptable results for this method, it has some limitations. for instance the front face must be fully visible and erect, the face must be completely facing the camera and must not lean to either side[30]. the viola-jones method has three components that work collectively to be detected quickly and accurately, and these components are the integrated picture for feature calculation, adaboost for feature selection and cascade to effectively reduce computational resources. it also uses haar-like features [31]. fig. 4. general architecture of viola-jones algorithm. fatima hardan al-khwarizmi engineering journal, vol. 18, no. 1, p.p. 3850 (2022) 43 after the faces are detected, they are surrounded by rectangles, and these rectangles are changed in color according to the distance between them. fig. 5. face detected by viola-jones. 4.2. measure social distancing measuring the distance between people is the second part of the proposed system. this part depends on the first part of the system, where in the first part people are detected and their locations in the image are determined. the positions of the individuals in the picture are four coordinates for each perimeter: x, y, w and h. x and y represent the upper left corner of the bounding rectangle, while w and h represent the width and height of the bounding rectangle of the detected object. these coordinates are used to check whether there is a violation of social distance or not by measuring the distance between the centers of the rectangles surrounding the detected face. the centers of the rectangles are calculated using equations 1 and 2. we assume that the central coordinates of the rectangle of the first face are ��� and ���and that the coordinates of the center of the second face are ��� and ���, and the euclidean distance[29] between them is measured by equation 3. xc= � � � � …(1) yc= � � � …(2) ed = ���� � ��� � � ���� � ��� � � …(3) next, the distance is compared with the experimentally measured threshold parameter to determine whether these two individuals violated social distance. a calibration factor is used to convert the euclidean distance from a pixel unit to a real-world unit, which is a unit cm, as in equation 4. after finding the value of the calibration factor through experiments, we multiply the found euclidean distance by the calibration factor we obtained to standardize the units. calibration factor = ��������� ������� �� �� ��������� �������� �� ������� …(4) a red box is placed on the people if the euclidean distance (ed) between them is less than the established distance (du), indicating a violation of the social distance between them. however if the ed is greater than the du, green boxes are placed to indicate that they are committed to social distancing. 5. training data we trained 138 pictures containing faces and 238 pictures without faces. the pictures were taken through a fixed raft camera at a height of 165 cm and after 400 cm from the iphone 12 pro max mobile, and all the pictures were taken in the laboratories of al-khwarizmi college of engineering. some of the pictures were taken of non-frontal faces, as well as of faces wearing masks and medical scenes. through the experiments all faces were identified. different numbers of the cascade stage were utilized during the training, where we used 5, 7 and 9, and for each stage we used 3 values for the fatima hardan al-khwarizmi engineering journal, vol. 18, no. 1, p.p. 3850 (2022) 44 false alarm rate, which represents the false positive rate, and the values in training were 10%, 7.5% and 5%. in total, we have 9 files that have been trained and images have been tested. 6. experimental results and discussion we trained the cascade classifiers used in the detection algorithm utilizing two types of feature descriptors, which are histograms of oriented gradient(hog) and local binary pattern(lbp). that is to choose those that give more positive results and more accuracy. when comparing the results that we obtained from the experiments, we find that the descriptors of the histograms give greater accuracy in detecting faces as in the fig.6, this result was obtained when using 9 stages of classification and the false alarm rate of 5%. a b fig. 6. face detection a. using hog features. b. using lbp features. on the other hand, we tested the system on the faces wearing masks, we found that the haar cascade classifiers detected them after we did the training, also we are comparing the results got with what the researchers muhanad ramzi and amar idrees [32] mentioned that these classes cannot detect the faces wearing the masks and we use the same picture. a b fig. 7. face detection with wearing masks a. results from our system. b. results from researchers [32]. fatima hardan al-khwarizmi engineering journal, vol. 18, no. 1, p.p. 3850 (2022) 45 fig. 8. results through using different number of cascaded stage with different values of false alarm rate. table 1, number of cascaded stages & false alarm rate with their results. no. of cascaded stage false alarm rate results 5 10% fig.6. a 5 7.5% fig.6. b 5 5% fig.6. c 7 10% fig.6. d 7 7.5% fig.6. e 7 5% fig.6. f 9 10% fig.6. g 9 7.5% fig.6. h 9 5% fig.6. i through the experiments and the results, it became clear that the higher the number of stages and/or the lower the percentage of false alarm rate the more accurate the detection of faces and the lower the error rate, as shown in the fig. 8. the 9 training files were used to obtain different values of tp, which represents the positive results, fp the false positive results, tn true negative results, and finally, fn the false negative results. figures 9 and 10 show these values and how they change by changing the number of cascade stages and the false alarm rate values. a b c d e f g h i fatima hardan al-khwarizmi engineering journal, vol. 18, no. 1, p.p. 3850 (2022) 46 fig. 9. results with different number of cascaded stage. fig. 10. results with different values of the false alarm rate. another was done, that was when people were sitting one behind the other. we had difficulty in detecting people in the event that the person's face was completely covered by the person sitting in front of him. as for the distance, it was measured correctly, but it depended on the detection of people. as shown in fig. 11a, two people out of 4 were detected and the distance between them was measured. in fig. 11b, all the people were detected and the distance between them was measured. fatima hardan al-khwarizmi engineering journal, vol. 18, no. 1, p.p. 3850 (2022) 47 a b fig. 11. face detect when people are sitting one behind the other. finally, the results of observing the distance between people is presented, where laboratory, the distance between people was determined as 200 cm, and it was found that it 1923.55 pixels through experiments, so this distance was fixed and the condition was given based on it, we also found the calibration factor based on these results as shown below by using equation 4. calibration factor = 200 1923.55⁄ =0.1039744223 �� �����⁄ a b c fig. 12.monitor social distancing (a) ed > du (b) ed < du (c) ed < du with wearing a mask. 7. conclusion this study, a monitoring system for measuring the distance between people was developed, which will be useful during the pandemic. with the spread of epidemics among people, social distancing was an important solution that had positive outcomes, hence, it was a mandatory requirement. violations of the safe distance could be detected through the monitoring system. the viola-jones algorithm was used to detect faces in the monitored places. the system was trained using 3 different numbers for the stages of the cascade classifier, which were 5, 7, and 9, with three different numbers for the false alarm rate, 5%, 7.5% and 10%. the best detection result obtained was when using 9 stages with 5% of the false alarm rate as it concluded that the lower fatima hardan al-khwarizmi engineering journal, vol. 18, no. 1, p.p. 3850 (2022) 48 the value of the false alarm rate and the higher the number of stages for the cascade classifier, the greater the accuracy of the detection of faces. after the faces were detected, the euclidean distance was measured between the centers of the rectangles surrounding the discovered persons. during the experiments, the distance of 2 meters between individuals was imposed by most governments and the world health organization, and it was found that it is approximately 1923 pixels. 2 meters was considered as the threshold at which the euclidean distance was compared with it after multiplying by calibration factor to determine the person’s violation of social distance or not. the results obtained were adequate, and the side faces and those wearing the masks were detected, which the system was trained to detect the faces in all cases and obtain the best results. 8. references [1] deep learning official website check it out on august 17, 2016. archived december 13, 2017 on the wayback machine website. 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[32] m. r. mohammed and a. i. daood, “smart surveillance system to monitor the committed violations during the pandemic.” http://journals.uob.edu.bh ط�� ��دان �� �� 1ا���د، ��18 � ا���ارز�� ا������� ا����� ،50 -38 )2022( 50 ظ آ�� رؤ�� $# م ! ����� � ( ) �) �� ا-,+� (� ا�+*� ا��0 ء ��. **ر�� ن ا��� * ��دان � ط�� *,**��� >;!اد 9+83� /ا-67ارز23 ا-1"! � 0/&� /ا-,&%+*(و'&%$ ھ"! � fatima.ibrahim1402@kecbu.uobaghdad.edu.iq :ا@-%?(و'2 ا-<(=!* ahmedalmusawi@kecbu.uobaghdad.edu.iq *!=)>-ا@-%?(و'2 ا: * �� ا��1 a96ا= � ا ?h .\3!7] إ-y= k?+ج ا-vw6 وھsا ، ظ61ره s"3 ا-8+-� 6hل ا7pq+ص k/l m&=n3 ا-6>+ء أg&h )i ، ط<&� أز3� اcن ا-8+� ار*!اء و3"1+ ، >1+ ا@-?hام =ef ا-?2 ا-6dاc8< !l ا-8+-,&� ا-yb� 3"[,� و`(w\ ، ا-6>+ء ا'?a+ر -,%+`y� _/?73� h/6@ً ا-!ول 83[ �!3\ ا-?2 ا-y/6ل أھ� m3 وھ6 ، ا@l+,?9&� وا-,�+`� ، ا-,m&<+b وfh( ، ا-%,+3+ت jk+?' 9&!ة �ا-_&(وس -,6ا19 !f?��. ا-,* )=6n* !=!8-ا m3 �,]'q7!م ا-?2 ا?�� '[+م ا�?(اح *� ، ا-6ر�� ھsه `2. ا@2l+,?9 ا-?<+v>??!l ا-p&,8 وا-?8/� ا@2l+"no ا-0s+ء *k+� k/l � ا-p&,8، 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modeling and simulation of hydraulic proportional control valves with different types of controllers sarah m. rashid*, maher yahya salloom** , nor haniza bakhtiar jemily *** and absamat h. **** *,**department of mechatronics engineering, al-khwarizmi college of engineering, university of baghdad, baghdad, iraq ***mechanical section, university kuala lumpur malaysian spanish institute, kulim hi-tech park, kulim 09000,malaysia ****school of mechanical engineering, engineering campus, university sains malaysia (usm), 14300 nibong tebal, seberang perai selatan, pulau pinang, malaysia corresponding author *email: saramr@mtu.edu.iq **email: dmahir@kecbu.uobaghdad.edu.iq ***email: norhaniza@unikl.edu.my ****email: hasnida@usm.my (received 30 october 2023; accepted 31 march 2024; published 1 june 2024) https://doi.org/10.22153/kej.2024.03.001 abstract numerous applications have been developed, primarily focusing on achieving platform equilibrium. the system may employ electric motors or hydraulic cylinders, conventional valves, or a control mechanism that utilizes pressure sensors. the majority of these sources exhibit inaccuracies, demonstrate a sluggish response time, and may require periodic reorganization. before implementing actual systems, it is imperative to develop a virtual system through the utilization of simulation techniques. this research aims to develop and evaluate a platform comprising two hydraulic cylinders and two proportional valves. the design of a hypothetical hydraulic system involves an analysis of the system and the derivation of its transfer function. subsequently, the performance of the system is assessed by identifying the optimal approach for acquiring the parameters kp, ki, and kd, an examination is conducted to optimize the existing genetic algorithm (ga) pid controller and the particle swarm optimization (pso) algorithm through the utilization of matlab simulation. the results indicate that the genetic algorithm (ga) pid algorithm outperforms the particle swarm optimization (pso) pid controller in enhancing system performance. the chosen error standard for the self-balance platform control system is the integral time absolute error (itae) type. the system exhibits an improved rate of convergence. keywords: hydraulic; proportional; mathematical model; simulation; pid; controller; genetic algorithm (ga); particle swarm optimization (pso) 1. introduction in the context of scientific and technological advancements, modern systems necessitate the attainment of optimal levels of performance and dependability by employing platform-stabilizing approaches. the stability systems of platforms demonstrate variety depending on the strategy employed for platform design and the mechanisms utilized for governing and maintaining the platform's consistent level position. maintaining the level of devices and equipment in laboratories is crucial for performance and preventing corrosion and damage to parts. utilizing the software tool archicad [1] begin the process of constructing a triangular-shaped balancing platform. the examined system is outfitted with a pair of hydraulic cylinders, mailto:dmahir@kecbu.uobaghdad.edu.iq https://doi.org/10.22153/kej.2024.03.001 sarah m. rashid al-khwarizmi engineering journal, vol. 20, no.2, p.p. 7889(2024) 57 facilitating the manipulation of two independent degrees of freedom. a mathematical model was created to provide an accurate description of the behavior shown by this system. the present model was produced by applying an optimization methodology that incorporates both a genetic algorithm and a particle swarm optimization algorithm utilized, specifically, certain multi-robot systems. a comparison analysis was undertaken to assess the efficacy of these two optimization methodologies [2].the hexapod parallel manipulator's stability was ensured through a specialized control system, incorporating advanced techniques like a telescopic boom and a gyroscopic self-leveling head for analysis[3]. the study focuses on creating a pedestal assembly for a medium-power transportable radar system, utilizing electromechanical and sliding actuators to adjust the azimuth and elevation settings of a 7-ton antenna [4].the design of an electro-hydraulicdriven parallel stabilization platform requires careful consideration of factors like fluid stiffness, damping properties, and the coupling effect between the fluid and structure, which increases the complexity of the modal and dynamic response characteristics[5]. the study presents a multipurpose amphibious platform for geognostic tasks in nearshore environments, regulated by flow rate and pressure, and using the inertial measurement unit for seafloor alignment.[6]the study proposes a 6-dof orthogonal hexapod with force feedback control for preventing vibration and steering of space observation systems, using hydraulic actuator force control.[7]the t shipborne-stabilized platform is crucial for maintaining shipborne equipment stability using the model predictive control approach (mpmpc), which predicts ship motion [8]. also, the stewart platform is a mechanical system that comprises a mobile platform and a stationary base linked by six extensible legs. it functions as a motion base and incorporates prismatic, universal, and spherical joints[9]. 2. design structure of the platform the system is designed utilizing the archicad drafting software, incorporating the necessary dimensions for implementation. as depicted in figure (1) and presented in table (1). fig .1. structural design of stabilizer platform. table 1, mechanical properties of the platform. element value the height of the platform dimensions of the platform the initial stroke of reference the initial stroke of actuation cylinders 49 cm 50 cm 14.5 cm 34.5cm 2. methodology 2.1 mathematical models the system is comprised of a pair of hydraulic cylinders equipped with two proportional control valves. the purpose of this mechanism is to control the horizontal and vertical displacements of every axis. the mathematical model of the system encompasses the proportional control valve and cylinder in isolation. in situations where load reactive forces cannot be disregarded, the input of the system is represented by the valve spool displacement, denoted as x, while the output of the sarah m. rashid al-khwarizmi engineering journal, vol. 20, no.2, p.p. 7889(2024) 58 system is represented by the power piston displacement, denoted as y. the linearization of a hydraulic system figure (2): (a) depicts a hydraulic motor. the device can be described as a hydraulic power amplifier and actuator that is regulated by a pilot valve. the pilot valve exhibits a balanced configuration, wherein the pressure forces exerted against it are uniformly distributed. the pilot valve possesses the capability to effectively manage a very high-power output while requiring minimal force for positioning. the relationship exhibits nonlinearity and can be transformed into a linear form by using ordinary differential equations (odes), with ps representing the pressure pump. figure (2) : (b) depicts an expanded depiction of the valve orifice area. the valve orifice areas of ports 1, 2, 3, and 4 shall be referred to as respective designations. the variables a1, a2, a3, and a4 are being referred to. furthermore, let us denote the flow rates through ports 1, 2, 3, and 4 as q1, q2, q3, and q4, respectively. it should be noted that a1 is equal to a3 and a2 is equal to a4 due to the symmetrical nature of the valve. given the assumption that the displacement x is small,[10] fig. 2. (a) hydraulic system (b) enlarged diagram of valve orifice area[10]. 𝐴 = ( 𝑥̥ 2 + 𝑋)𝐾 … (1)[10] where a is an area, k is a constant, xo is a displacement. in addition, we presume that the return pressure p0 in the return line is negligible and therefore can be disregarded. then, using figure (2) :(a) as a reference, the flow rates through valve orifices are measured as follows: q=ca√ 2𝑔 △𝑃 𝛾 … (2)[10] where (c) is discharge and (𝛾) is specific weight. (g) is the acceleration of gravity. the flow rate (g) to the left-hand side of the e power piston is: q=( 𝑥̥ 2 + 𝑋)𝐾√ 2𝑔 △𝑃 𝛾 … (3)[10] q=c√△ 𝑃 ( 𝑥̥ 2 + 𝑋) … (4)[10] by applying the linearization technique q= k₁ x – k2 △ 𝑝 … (5)[10] where △ 𝑝 the pressure drops across the orifice is a function of the supply pressure ps and the pressure difference △ 𝑝 = 𝑃1 − 𝑃2. also, q= a 𝑑𝑦 𝑑𝑡 …. (6)[10] where 𝑑𝑦 𝑑𝑡 the speed of the piston mass ∑𝐹 = 𝑚 �̈� △ 𝑃 ∗ 𝐴 − 𝐾 𝑌 − 𝐶�̇� = �̇��̈� … (7)[10] tack laplace transform: q(s)= = k₁ x(s) – k2 △ 𝑃(s) …*5 q= a s y(s)…*6 a △ 𝑃(s)=y(s) [m s²+c s + k] …*7 rearmament equation 3. △ 𝑃(s)= 𝑌(𝑠)[𝑚 𝑠²+𝑐 𝑠+ 𝑘] 𝐴 … (8) after substituting the equations, we get: t(s)= 𝑌(𝑠) 𝑋(𝑠) = 𝑘₁ 𝑘2 𝐴 [𝑚 𝑠2+(𝑐−𝐴)𝑠+𝑘] … (9) based on parameters taken from previous research (k₁, k2, c, k).[11] .additionally, it has the potential to be utilized within this particular system. the values of (a,m) are assumed to be from the real system. table 2 provides a comprehensive overview of the information presented. t(s)= 0.0825 1.716 𝑠2 +56.378 𝑠+3575 … (10) t(s)= 0.04807 𝑠2 +32.854 𝑠+2083.33 … (11) sarah m. rashid al-khwarizmi engineering journal, vol. 20, no.2, p.p. 7889(2024) 59 table 2, parameters of hydraulic system[12][13][11] parameters value unit description k₁ 0.0825 m/a gain of spool valve(vertical) k2 8.25e-5 m/ma gain of spool valve (lateral, longi) a 1.256e-3 m² piston area of lateral axis m 13 kg load mass c 400 ns/m load damping k 2500 n/m load spring stiffness 2.2 pid controller a proportional integral derivative (pid) controller is an automated and precise control system utilized for regulating various parameters, such as temperature, pressure, and speed, to achieve desired values. control loop feedback is the fundamental mechanism employed in pid controllers. a pid algorithm computes the error by determining the discrepancy between the current value and the target value and subsequently adjusts the controlling parameters accordingly. this error is iteratively computed until the process terminates. the proportional component is utilized to quantify the discrepancy between the desired value and the actual value, and it is accountable for generating the remedial response. the integral is utilized to compute the cumulative sum of historical error values, which is then integrated to determine the integral term. when a mistake is removed from the system, the rate of increase of this integral ceases. the derivative is employed to forecast the anticipated error levels in the future, relying on the current values. the controlling effect can be enhanced by having a system with a high rate of change, which is likewise dependent on derivatives. the name "proportional integral derivative (pid) controller" is derived from the combination of these three operations [11]. output=kₚe(t)+kᵢ ∫ 𝑒 (𝑡)dt+kd 𝑑 𝑑𝑡 e(t)…(12)[11] where: e = setpoint -input 𝐾𝑝 = proportional constant 𝐾𝑖 = integral constant 𝐾𝑑 = derivative constant 2.3 ga algorithm genetic algorithms (gas) are grounded in fundamental principles such as natural selection and natural inheritance. natural selection refers to the process through which organisms with advantageous adaptations to their environment are more likely to survive and reproduce, while those lacking such adaptations are more likely to be removed. this elimination occurs due to the absence of favorable hereditary traits, which are passed on through the interbreeding of selected individuals to generate offspring. in the context of genetic algorithms (ga), the initial population is determined using a fully random process in georgia. the subsequent stages of ga can be categorized into two distinct phases: genetic operations, which involve crossover and mutation, and evolutionary processes, which encompass selection. the initial step in problem-solving involves encoding a set of points, known as genetic algorithms (gas). every configuration generates a collection of potential solutions, referred to as a chromosome or individual, within the population. [14]chromosomes consist of sequences of genetic material known as genes. the design process is utilized to create an appropriate algorithm. the genetic algorithm (ga) is elected as the method of choice for optimizing the parameters of the pid controller, specifically kp, ki, and kd, through a self-tuning process. the design process revolves around the utilization of a genetic algorithm (ga) to optimize the classic proportional-integral-derivative (pid) controller for self-balance platform control [15]. empirical investigations have demonstrated that the use of the genetic algorithm (ga) and the proportional-integral-derivative (pid) controller yields superior outcomes in the regulation of selfbalancing robots compared to traditional pid control methods [14]. 2.4 pso algorithm particle swarm optimization (pso) is a widely recognized and influential optimization method that draws inspiration from natural swarm behavior. the popularity of this nature-inspired technique has experienced a significant surge due to its inherent characteristics of flexibility and ease of implementation. particle swarm optimization (pso) has garnered significant attention across various domains of academic inquiry [13]. sarah m. rashid al-khwarizmi engineering journal, vol. 20, no.2, p.p. 7889(2024) 60 3. simulation and experiment this section presents the simulation model of a self-balancing platform, the input and output systems and the transfer functions of the platform. figure 3 presents the simulation model with a conventional pid controller, which enhances the performance of the self-balancing platform. the simulation model is shown in figure 4. it uses a genetic algorithm (ga) to find the most important changes needed by choosing the best values for the pid controller's parameters. this makes the system better. while figure 5 illustrates the simulation model utilizing the particle swarm optimization (pso) algorithm to identify crucial adjustments by selecting optimal values for the control parameters of the proportional-integral-derivative (pid) controller for system optimization fig. 3. simulation model of self-balance platform with tuning pid controller. fig. 4. simulation model of self-balance platform with ga-pid controller. fig. 5. simulation model of a self-balance platform with pso-pid controller. sarah m. rashid al-khwarizmi engineering journal, vol. 20, no.2, p.p. 7889(2024) 61 4. simulation results in this section, there are three parts. the first part is the simulation results with the pid controller shown in subsection 4.1. the second part is the simulation results with the ga_pid controller that is shown in subsection 4.2. the third part is the simulation results with the pso-pid controller that is shown in subsection 4.3 table 2, system parameters in each optimization method. table 3, the detailed matlab results. 4.1 simulation results with pid controller this section examines the system's response when a pid controller is employed to enhance the operation and performance of a self-balancing platform. the results presented in figure 6 demonstrate the system's response, which exhibits a reduction in overshoot to 0.181%, a rise time of 0.0247 seconds, and a settling time of 0.189 seconds. consequently, the system achieves a steady state in a shorter duration compared to the initial scenario in the absence of the controller. the parameters of the pid controller are assigned as follow: kp = 36683.9058, kd = 406.5704, and ki = 819836.3269. fig. 6. piston stroke displacement using pid controller. 4.2 simulation results with pid controller this section focuses on the application of genetic-pid optimization to enhance the response of the self-balancing platform and achieve optimal outcomes. the aim is to enhance the performance and functionality of the proportional control valve by optimizing the parameters of the pid controller. figure 7(a) depicts the system's response obtained by the utilization of ga-pid optimization. the provided data demonstrates that the overshoot value is 8.7663, the settling durations for each instance are 0.0294 seconds, the rise time is 0.1316 seconds, and the system parameters raise time(sec) settling time (sec) overshoot pid 0.0247 0.189 0.181% ga-pid 0.0294 0.136 8.7663 pso-pid 0.0194 0.1926 0.0046 parameters kp ki kd pid 36683.9058 819836.3269 406.5704 ga-pid 0.3112*105 8.8982*105 0.0045*105 pso-pid 0.349*105 8.8909*105 0.0044*105 sarah m. rashid al-khwarizmi engineering journal, vol. 20, no.2, p.p. 7889(2024) 62 achieves a steady state in a significantly shorter duration compared to previous states. at iteration 100, the control parameters have the following values: kp = 0.3112 e5, kd = 0.0045 e5, and ki = 8.8982 e5. in figure 7 (b), the optimization tools utilized for ga-pid are depicted. fig. 7. (a) piston stroke displacement using ga_pid controller (b) piston stroke displacement using ga_pid controller at iteration 100. 4.3 simulation results with pso-pid controller this part is dedicated to examining the utilization of pso-pid optimization in order to improve the response of the self-balancing platform and attain optimal results. the objective is to improve the operational efficiency and capabilities of the proportional control valve through the optimization of the pid controller's parameters. the response of the system acquired by the application of pso-pid optimization is illustrated in figure 8. the data supplied indicates that the overshoot value is 0.0046. the settling durations for each instance are measured at 0.1926 seconds, while the rise time is also 0.1926 seconds. furthermore, it is observed that the system achieves a steady state with a considerably shorter duration compared to previous states. at the 100th iteration, the control parameters are seen to possess the subsequent values: kp = 0.349 x 10^5, kd = 0.0044 x 10^5, and ki = 8.8909 x 10^5. fig. 8. piston stroke displacement using pso-pid controller. sarah m. rashid al-khwarizmi engineering journal, vol. 20, no.2, p.p. 5664(2024) 63 5. conclusion the paper introduces the pso approach as a means of modifying the control parameters of the conventional pid controller utilized in the construction of a self-balancing platform control system. the study proposes the utilization of a genetic method to modify the control parameters of the conventional pid controller, which was originally built for a self-balancing platform control system. the genetic controller exhibits significantly faster temporal response qualities in comparison to the pid controller, and it further furnishes us with the starting point for the control parameter values. the ga-pid controller demonstrates superior performance in terms of settling time, rising time, and overshoot. furthermore, it should be noted that the error margin associated with ga-pid is significantly lower compared to conventional control methods. as a result, ga-pid has proven to be highly effective in achieving optimal outcomes for the self-balance platform. references [1] graphisoft, “archicad 22.” budapest, hungary. [online]. available: http://www.graphisoft.com/archicad/ [2] w. h. bangyal et al., “an improved particle swarm optimization algorithm for data classification,” applied sciences (switzerland), vol. 13, no. 1, 2023, doi: 10.3390/app13010283. [3] w. p. hunek et al., “a measurement-aided control system for stabilization of the reallife stewart platform,” sensors, vol. 22, no. 19, pp. 1–12, 2022, doi: 10.3390/s22197271. [4] s. kumar, s. pazhanivel, k. a. kumar, and n. m. athawale, “design and development of pedestal assembly for medium power active array transportable radar,” vol. 2015, no. december, pp. 2–5, 2015. [5] w. wang, “analysis of vibration characteristics of electrohydraulic 3-ups / s parallel stabilized platform,” pp. 0–13, 2023. [6] l. pugi et al., “development of a multifunctional amphibious platform for near shore geognostic activities,” chem eng trans, vol. 91, no. april, pp. 163–168, 2022, doi: 10.3303/cet2291028. [7] m. taghizadeh and m. javad yarmohammadi, “development of a self-tuning pid controller on hydraulically actuated stewart platform stabilizer with base excitation,” int j control autom syst, vol. 16, no. 6, pp. 2990–2999, 2018, doi: 10.1007/s12555-016-0559-8. [8] h. qiang, s. jin, x. feng, d. xue, and l. zhang, “model predictive control of a shipborne hydraulic parallel stabilized platform based on ship motion prediction,” ieee access, vol. 8, pp. 181880–181892, 2020, doi: 10.1109/access.2020.2992458. [9] m. becerra-vargas and e. m. belo, “application of h1 theory to a 6 dof flight simulator motion base,” journal of the brazilian society of mechanical sciences and engineering, vol. 34, no. 2, pp. 193–204, 2012, doi: 10.1590/s1678-58782012000200011. [10] varios, “modern control engineering by k.ogata (solucionario).pdf.” [11] j. w. kim, d. j. xuan, and y. b. kim, “robust control application for a three-axis road simulator,” journal of mechanical science and technology, vol. 25, no. 1, pp. 221–231, 2011, doi: 10.1007/s12206-0101104-y. [12] p. i. i. data, “valves, direct operated, without electrical position feedback,” pp. 1– 12. [13] jain, meetu, et al. "an overview of variants and advancements of pso algorithm." applied sciences 12.17 (2022): 8392. [14] p. karpagavalli and a. ebenezer jeyakumar, “simulation analysis on proportional integral and derivative control of closed loop dc motor drive with bipolar voltage switching,” am j appl sci, vol. 10, no. 7, pp. 714–723, 2013, doi: 10.3844/ajassp.2013.714.723. [15] h. s. dakheel, z. b. abdullah, and s. w. shneen, “advanced optimal ga-pid controller for bldc motor,” bulletin of electrical engineering and informatics, vol. 12, no. 4, pp. 2077–2086, 2023, doi: 10.11591/eei.v12i4.4649. (2024) 56-64، صفحة 2، العدد20مجلة الخوارزمي الهندسية المجلد سارة محمد رشيد 64 نمذجة ومحاكاة صمامات التحكم التناسبي الهيدروليكي مع أنواع مختلفة من وحدات التحكم ،***نور هانيزا باكثير جميلي ،**ماهر يحيى سلوم، *محمد رشيد هسار ****هاسنيدا عبد الصمد العراق ،بغداد ،جامعة بغداد ،كلية الهندسة الخوارزمي ،قسم هندسة الميكاترونكس *،** ماليزيا ،09000كوليم ،مجمع كوليم للتكنولوجيا الفائقة ،المعهد اإلسباني الماليزي بجامعة كوااللمبور ،القسم الميكانيكي *** ماليزيا ،جزيرة بينانك ،سيبيرانك بيراي الجنوبية ،يبونك تيبال 14300 ،(usm)جامعة العلوم الماليزية ،مجمع الهندسة ،كلية الهندسة الميكانيكية **** saramr@mtu.edu.iq :البريد االلكتروني* dmahir@kecbu.uobaghdad.edu.iq :البريد االلكتروني** norhaniza@unikl.edu.my :البريد االلكتروني*** hasnida@usm.my :البريد االلكتروني**** المستخلص المنصة لضمان ترمي هذه الدراسة إلى تصميم منصة ذاتية التوازن وتطويرها وتستخدم في العديد من التطبيقات الصناعية التي تحتاج الى استواء سطح عن طريق صمامي سيطرة هيدروليكية تناسبية. يتضمن تصميم بهمايتم التحكم عملها بكفاية عالية. تم تصميم منصة وتنفيذها تتكون من اسطوانتين هيدروليكية من .kd و kiو kp اناتالنظام الهيدروليكي االفتراضي تحليل النظام واشتقاقه. وبعد ذلك، تم تقييم أداء النظام من خالل تحديد النهج األمثل للحصول على البي الحالية وخوارزمية تحسين سرب الجسيمات (ga) للخوارزمية الجينية pid التحكم ، تم إجراء فحص لتحسين وحدةmatlab خالل استخدام محاكاة (pso). تشير النتائج إلى أن خوارزمية التحكم pid للخوارزمية الجينية (ga) تتفوق في تحسين أداء النظام من خوارزمية تحسين سرب الجسيمات (pso) يُظهر النظام معدالا .(itae) ام التحكم في منصة التوازن الذاتي هو نوع الخطأ المطلق للوقت المتكامل.وكان معيار التحكم في األخطاء الذي تم اختياره لنظ .محّسناا للتقارب this is an open access article under the cc by license : al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 21, no. 2, june, (2025), pp. 93–105 recent tools of software-defined networking traffic generation and data collection tabarak yassin khudhair1* and omar ali athab2 1,2department of information and communications engineering, al-khwarizmi college of engineering, university of baghdad, baghdad, iraq corresponding author’s email:tabarak.taha1603@kecbu.uobaghdad.edu.iq (received 13 november 2023; revised 7 june 2024; accepted 26 june 2024; published 1 june 2025) https://doi.org/10.22153/kej.2025.06.002 abstract software-defined networking (sdn) has proven its superiority in addressing ordinary network problems, such as scalability, agility and security. this advantage of sdn comes because of its separation of the control plane from the data plane. although many studies have focused on sdn management, monitoring, control and improving quality of service, only a few are focused on presenting what is used to generate traffic and collect data. the literature also lacks comparisons amongst the tools and methods used in this context. therefore, this study introduces the recent tools used to simulate, generate and obtain traffic statistics from an sdn environment. in addition, the methods used in sdn data gathering are compared to explore the capability of each one and hence, determine the suitable environment for each method. the sdn testbed is simulated using mininet software with tree topology and openflow switches. an ryu controller was connected to control forwarding. the famous tools iperf3, ping and python scripts are used to generate network datasets from selected devices in the network. wireshark, the ryu application and the ovs-ofctl command are used to monitor and gather the dataset. results show success in generating several types of network metrics to be used in the future for training machine or deep learning algorithms. therefore, when generating data for the purpose of congestion control, iperf3 is the best tool, whilst ping is useful when generating data for the purpose of detecting distributed denial-of-service attacks. ryu applications are the most suitable monitoring tool for obtaining all network details, such as the topology, characteristics and statistics of the components. many obstacles and mistakes are also explored and listed to be prevented when researchers try to generate such datasets in their next scientific efforts. keywords: sdn; openflow1.3; ryu controller; mininet; iperf3; wireshark; python. 1. introduction software-defined networking (sdn) is a networking paradigm that decouples the network’s control plane from the data plane [1]. in traditional networks, the control plane and data plane are coupled. in other words, the network devices, such as routers and switches, are responsible for making decisions about how to forward traffic [2]. the separation of the control and data planes in sdn provides a number of advantages, such as the ease of making changes to network configuration. the changes can be made to the centralised controller rather than to individual devices, which can be particularly beneficial in many environments, such as data centres [3], [4], 5g [5] and iot networks [6], where the number and types of workloads can change frequently. sdn also allows for the network to be programmed using software applications . many studies have been conducted in the field of generating and collecting sdn flows. mu [4] used the built-in iperf tool with a python script to simulate 25.6 mb and 256 kb flows using the transmission control protocol (tcp)/internet protocol in 1 gb/s links. the configuration overhead was reduced, and execution time was improved by 50%, but how a built-in iperf was used inside a python script is not explained. jiang et al. [6] utilised the iperf tool to generate traffic and send it in links that have a bandwidth (bw) of 1 gbps and https://doi.org/10.22153/kej.2025.06.002 tabarak yassin khudhair al-khwarizmi engineering journal, vol. 21, no.2, pp. 93105 (2025) 94 a round-trip time (rtt) of 0.3 ms to achieve high throughput with increasing packet loss rates and rtt to control congestion; however, the controller’s type or version is not referred to. zhao et al. [7] employed the iperf tool to generate traffic between pairs of hosts in intervals equal to 10 s, and the flow load increased from 0 mbit/s to 25 mbit/s to create congestion in the network. sdn controller messages were also used to monitor network status and request information about the topology, quality of service (qos) and links. given their efforts, congestion was successfully controlled and reduced, and network performance was increased. however, the specific built-in or external tool that was used, the version of the tool and the protocol used in their work are not explained. wu et al. [8] used the iperf tool to simulate user datagram protocol (udp) traffic between three host pairs at the same time with a changed transmission rate to predict link congestion and reach 95.4% accuracy. meena et al. [9] investigated wireshark, the ovsofctl dump-flows instruction and the pingallfull command to reduce the first packet forwarding time and succeeded in reducing 83% of the forwarding time. wireshark was used to capture and analyse packets, the ovs-ofctl dump-flows instruction to capture and analyse flow entries of openflow switches, and a built-in pingallfull command on the mininet to measure rtt, yet why the pingallfull command was selected instead of ping and the advantages of using this tool are not explained. ali et al. [10] applied a built-in iperf3 tool inside mininet to generate tcp and udp traffic between hosts and measure the throughput and transfer data to enhance traffic load balancing, even though the bw and transfer duration of the generated traffic is not determined by them. nougnanke [11] employed the iperf tool to measure delay, jitter and bw to control congestion. diel et al. [12] used the iperf3 tool to generate 5 gb of flows and send them in links with 1 gbps of capacity, and the ryu controller was used to collect the sent and received numbers of packets, bytes, drops, errors and collisions to avoid congestion in the data centre, which succeeded in reducing flow completion time by half, but the specific tool or method used to collect data was not clarified. mohsin and hamad [13] implemented a ping command inside a python script to generate internet control message protocol (icmp) flood traffic between hosts at different rates for single topology, linear topology and linear with multicontroller topology, respectively, to detect and eliminate ddos attacks. increased switches in single topology reduce load, eliminate attack effects quickly and minimise detection and mitigation time. increased controllers enhance detection and mitigation by minimising error rates, but how this method was implemented is not stated. this research aims to address the shortcomings found in the literature, such as the lack of details about the tools and methods used to generate data in sdn networks. failing to explain how to hire many tools or how to utilise different tools to accomplish the same task is a shortcoming of many researchers. moreover, this work focuses on avoiding practical programming obstacles during data generation, such as the mismatch between the versions of all of the software and the programming languages used in each of the network components. this study also addresses technical errors to achieve an acceptable reliability in the data, e.g. time synchronisation when using more than one tool between specific host pairs, when used as a dataset input in machine learning and deep learning training. section 2 explains the sdn layers and devices used in the structure of the network. section 3 demonstrates the work infrastructure and design. section 4 presents the simulated topology used in this study. section 5 shows the methods and tools used to generate traffic in sdn. section 6 states methods and tools used to monitor network statistics and performance. section 7 conducts a comparison between all the methods and tools included in this study. section 8 contains the main conclusion of the study. 2. sdn layers and devices the sdn network system model consists of three layers: the data layer, the control layer and the application layer [14]. the application layer contains network services and applications that interact with the control layer [5] . the control layer provides a centralised global view of the entire network, represented by controllers, that provides updates and collects data from network switches [12]. given a centralised view of every device in the network, all network characteristics and metrics can be monitored and measured. the controller gathers real-time statistics from all the switches through openflow messages that inquire the state of the switches periodically [16], allowing the controller to be directly programmable and have full management of the switches [17]. the controller manages the switches through the southbound interface, whilst the application layer communicates with the controller through the northbound interface. the northbound interface personalises the application of the sdn network [18]. tabarak yassin khudhair al-khwarizmi engineering journal, vol. 21, no.2, pp. 93105 (2025) 95 the data layer consists of openflow switches and terminal hosts that transmit packets according to the rules imposed by the control layer [19]. sdn uses the openflow protocol to deal with openflow switches, allowing the controller and switches to understand each other. openflow switches consist of several flow tables [3]. a flow table is composed of multiple flow entries that include the following: match fields, used to match flows; priority, used to match the priority of the flow; counters, to be refreshed to match the packets; instructions, to determine the action taken; timeouts, the total time or idle time before the timeout ends; and cookies, the implicit value of the data assigned by the controller [20]. 3. infrastructure and design of the work the work was divided into four main parts: topology simulation, traffic generation, data collection and tool comparison, as shown in figure 1. the topology simulation part consists of a description of the simulator, starting from a simulation of the topology, then its connection to the controller, until the operation of all the network components. the second part explains how traffic is generated using different tools such as iperf3, ping, and python scripts. afterwards, in part three, data are collected on different network devices using many applications and tools such as wireshark, sdn controllers and a mininet simulator. in the final part, all the tools that generate traffic were compared, and the data are collected separately. fig. 1. workflow diagram 4. simulation this research was performed to generate and collect flow statistics from the sdn switches. the topology used in this study was created in a mininet simulator [21], and the openflow protocol v1.3 was used. version 2.3.1b4 of mininet, a software simulator, was installed on a linux operating system and initialised for the sdn network simulation. it can simulate many network topologies, such as star, linear, tree, etc. an ryu controller is an sdn framework software, version 4.34 was used in this work. the ryu controller is coded with python and installed separately from mininet but has the ability to connect with mininet. the ryu controller was selected instead of the default pox controller because of its ability to support all openflow protocol versions. as shown in figure 2, the network was made in the form of a tree topology in depth 3, which contains one controller, seven switches and eight hosts. the switches are provided by mininet and run using open vswitch version 2.13.8. all switches have three ports, except s1, which has two ports, which work as sending and receiving ports. the hosts are pcs provided by mininet to send traffic. tabarak yassin khudhair al-khwarizmi engineering journal, vol. 21, no.2, pp. 93105 (2025) 96 fig. 2. sdn topology 5. methodologies to generate sdn traffic many tools are built-in or built-out in the mininet simulator to generate traffic between end hosts and measure specific network performance attributes. the most common and widely used tools are iperf, ping and python scripts. 5.1. iperf3 iperf [22] is a built-out mininet tool that generates and simulates tcp and udp traffic between any pair of hosts, one of which is a server and the other a client. the iperf tool can also measure network performance parameters such bw, jitter and transferring data . figure 3 shows a sample of the generated traffic using the iperf3 tool between h2 as a server and h5 as a client; given that they are located in two different subtrees, this forces the traffic to pass through most of the switches to reach the client. tcp is used in part a of figure 3, and udp is used in part b. the id in the list represents the identification number of the connection. the ‘interval’ is the time interval to report the throughput. ‘transfer’ represents how much data was transferred in each interval. ‘bitrate’ is the measured throughput in each interval. ‘retr’ is the number of tcp segments retransmitted in each interval. ‘congestion window’ (cwnd) indicates the congestion window size in each interval. ‘jitter’ represents the difference in packet delay. finally, ‘lost/total’ indicates the number of lost datagrams over the total number of datagrams . (a) tcp traffic tabarak yassin khudhair al-khwarizmi engineering journal, vol. 21, no.2, pp. 93105 (2025) 97 (b) udp traffic fig. 3. output of iperf3 tool to generate (a) tcp traffic, (b) udp traffic 5.2. ping ping is another tool that generates icmp traffic between hosts and sends icmp echo request and echo reply messages over the network to a targeted host. ping can be used to determine the number of transmitted and received packets, packet loss percentage, total time of transmission and the rtt for end-to-end network hosts . figure 4 shows the output result of using the ping tool in the sdn topology mentioned in figure 2. as shown in figure 4-a, h6 pings in 10 packets to h3 by using its ip, whereas in figure 4-b, a built-in ping tool is used between h1 and h7 by sending 10 packets with a 5 kb data size. hosts are selected to measure the performance between different subtrees on each side. (a) (b) fig. 4. using a ping tool to generate traffic: (a) external host terminal, (b) built-in tool 5.3. python scripts the mininet simulator supports the ability to run built-out python scripts sequentially within each endpoint host, thus allowing tcp or udp traffic to be generated and sent to the predefined destination at the given port number . tabarak yassin khudhair al-khwarizmi engineering journal, vol. 21, no.2, pp. 93105 (2025) 98 figure 5 shows an example of a tcp client – server program. the program is a simple e-mail application where the server is running on host 3 and the clients, on hosts 4 and 8, connect to the server to view received e-mails or send a new one . fig. 5. running python script to generate traffic between hosts 6. methods of traffic monitoring many different monitoring techniques are used with mininet to capture statistics about the sdn network by using some of the openflow messages specified in the openflow specification [23]. the most common methods used to obtain network statistics are the controller itself and the wireshark tool . 6.1. wireshark tool wireshark [24] is a packet-capture tool. wireshark contains three panes called the packet list pane, the packet details pane, and the packet bytes pane. the packet list pane displays packets from a selected interface. the packet details pane displays the protocol fields used in the selected packet from the packet list pane. finally, the packet bytes pane displays the data of a packet in a hex dump . figure 6 shows a wireshark window that runs in the s1 to display openflow packets between the switch and the controller in the topology of figure 2. as shown, the packet list pane displays the packet number, capture time of a packet, ip address and port number of the source and destination, length of packet and the packet message type. when selecting a packet, more details about the header and data are presented in the packet details and packet bytes panes . fig. 6. output of wireshark tool tabarak yassin khudhair al-khwarizmi engineering journal, vol. 21, no.2, pp. 93105 (2025) 99 6.2. sdn controller applications the controller is connected to sdn switches through the openflow protocol. the controller sends request messages to acquire statistics about the port, flow entry, queue, group, meter and topology statistics. when a switch receives a ‘request’ message, it sends out a response with a ‘reply’ message. this message holds the statistics collected from the switch counters and can also query about the link load, network topology and network qos parameters . 6.2.1. simple_monitor_13.py the controller sends ‘ofportstatsrequest’ and ‘ofpflowstatsrequest’ messages and receives ‘ofportstatsreply’ and ‘ofpflowstatsreply’ messages that include information about both port statistics, the transmitted and received number of dropped packets, bytes, errors and collisions. it also receives messages about the flow statistics, the duration of the flow, packet and byte count . figure 7 shows the output of using the ryu simple_monitor_13.py script to determine which attributes’ statistics are needed in ‘ofportstatsreply’ and ‘ofpflowstatsreply’ messages for switch 6 in figure 2 . (a) (b) fig. 7. simple_monitor_13.py outputs for (a) port statistics and (b) flow statistics 6.2.2. gui-topology.py gui-topology.py is a distinct ryu application that views the topology’s switches, ports of each link and the switch id as data-path-id (dpid). this script also provides information about flows for each switch. figure 8 shows the information that was provided from the gui-topology application . tabarak yassin khudhair al-khwarizmi engineering journal, vol. 21, no.2, pp. 93105 (2025) 100 fig. 8. gui-topology application for viewing sdn topology and flow statistics 6.2.3. flowmanager.py flowmanager.py [25] is a web application that views the switches and hosts of the topology, ports in each switch and host, switch id and host mac address. this application can also provide information about switches. figure 9 shows the topology that was presented using the flowmanager.py application. fig. 9. flowmanager application for viewing sdn topology and switch statistics tabarak yassin khudhair al-khwarizmi engineering journal, vol. 21, no.2, pp. 93105 (2025) 101 6.3. mininet commands mininet offers a built-in command-line interface (cli) for managing virtual networks and communicating with them. network topologies, network starts and stops, network device configurations and connectivity tests are all accomplished with the use of cli commands . 6.3.1. built-in iperf figure 10 shows the result of using a built-in iperf tool to measure the bw of tcp and udp protocols between two pairs of hosts from figure 2. when comparing the results with the results of figure 3, the same results are present, but a built-in tool divided the bw into uplink and downlink . (a) tcp traffic (b) udp traffic fig. 10. use of a built-in iperf tool to measure the bw of (a) tcp traffic and (b) udp traffic 6.3.2. built-in ovs-ofctl one of the most important tools for controlling and adjusting open vswitch (ovs) switches in mininet networks is the ovs-ofctl command. it offers an extensive feature set for specifying switch parameters, collecting performance data and managing switch behavior. by understanding and utilising the ovs-ofctl command, users can effectively manage and optimise mininet networks for various testing and experimentation purposes figure 11 shows the results when ovs-ofctl commands are called in for port statistics in part a and flow statistics in part b. (a) (b) fig. 11. view port and flow statistics by using the ovs-ofctl command: (a) port statistic, (b) flow statistic tabarak yassin khudhair al-khwarizmi engineering journal, vol. 21, no.2, pp. 93105 (2025) 102 7. discussion and comparisons in recent years, sdn has gained considerable attention and popularity due to its ability to integrate with machine learning and deep learning, which enables sdn to leverage intelligent algorithms and data analytics to optimise network performance and enhance security. for that, an efficient dataset should be gathered to train the learning algorithm. however, no current application or tool can collect all the required datasets in various sdn networks. for that, this study offers the most popular methods and tools to generate various data and collect the required metrics . table 1 compares the tools presented in section 5. as shown in table 1, the iperf3, ping and python scripts can be used to generate traffic in sdn. scripts written using the python language are used to generate traffic between hosts and are sometimes used to save the results from other tools and applications in a comma-separated values file (csv) or json file, whilst iperf3 and ping are used to generate traffic in sdn. it shows that iperf3 is widely used to generate traffic for many network applications, such as congestion control and load balancing, whilst for ddos attacks, the ping tool is widely used to generate attacks. therefore, the selection of the tool depends on what the application demands. table 1, comparison of tools that generate data in this study tool packet generated type work style tool type application iperf3 tcp and udp segments client–server pair built-out congestion controlling, predicting and avoiding. traffic load balancing ping icmp datagrams source–destination pair built-in and built-out detect ddos attacks. python scripts http, dns, ftp, and smtp messages client–server pair built-out flow management. detect ddos attacks table 2 compares the tools presented in section 6. as shown in table 2, the openflow command ‘ovs-ofctl’ is used to monitor and configure switches. it can also view the states of the switches such as table entries, features and configurations to analyse the flow in the switches. wireshark is used for capturing packets and viewing their details to control forwarding time. simple_mointor_13 is an ryu application script that is written in python and is used to send stats and request messages from the controller to the switches to inform about every feature and entry. when the controller receives stats and reply messages, it updates its records and stores the new records in a csv or json file. gui-topology is another ryu application that is used to view the topology that was implemented. gui-topology only views switches and prints their id and uses ports to link between them. gui-topology can also view a summary of flow statistics for each switch. flowmanager is another ryu script that is used to view network topology. it differs from gui-topology by showing hosts and printing their mac or ip address. whilst iperf and ping are used to generate traffic in sdn, each one measures different metrics. iperf measures bw, throughput, the number of retransmitted segments, cwnd, jitter and the number of lost datagrams, whilst ping measures rtt, the number of transmitted and received packets, packet loss and the time of transmission. as a result, the application or the metrics the researcher wishes to measure or examine will determine which tool is best. tabarak yassin khudhair al-khwarizmi engineering journal, vol. 21, no.2, pp. 93105 (2025) 103 table 2, comparison of tools that collected data in this study tool metrics collected monitoring work style tool type application wireshark header and data fields of the protocol anywhere in network built-out reduce forwarding time simple_mointor_13 switch statistics such as flow, port, queue, vlan, meter table, etc. centralised controller built-out ryu congestion controlling and avoiding. gui-topology switch id, port number, and flow statistics centralised controller built-out ryu topology discovering. flowmanager switch id, hosts mac or ip address, and port numbers. centralised controller built-out ryu topology discovering. iperf3 bandwidth, throughput, number of retransmitted segments, cwnd, jitter, and number of lost datagrams end-to-end hosts built-in mininet congestion controlling, predicting and avoiding. traffic load-balancing ping rtt, number of transmitted and received packets, packet loss, and time of transmission. end-to-end hosts built-in mininet detect ddos attacks. ovs-ofctl command switch statistics like ports, flows, queues, and vlan switch ports built-in mininet reduce forwarding time 8. conclusion a mininet simulator is used to create sdn topologies and connect to controllers. this tool can integrate with many tools to simulate real networks. one of these tools is iperf3, which is used to generate traffic between two hosts and measure the number of bytes that can be sent, bw, cwnd, number of retransmitted segments, jitter and the number of lost datagrams. another important tool is ping, a tool that sends icmp packets between two hosts and measures the rtt, time-to-life, number of segments and the time of transfer. python scripts can also run on the mininet and generate traffic between hosts. all three of the previous tools are used to generate traffic, but mininet also has tools to capture traffic and view information, such as the ryu controller application. wireshark is one such tool that captures packets and displays their headers and data. ovs-ofctl is another built-in command that is integrated into mininet to view statistics about the network, such as ports, queues, etc. gui-topology and flowmanager are ryu controller applications used to monitor and view network topology, switches’ ids, host mac addresses and port numbers. this study was conducted to view the most used tools that connect with the sdn environment to generate traffic and collect data. after explaining each tool, comparisons were added to clarify the difference in work style, type and the applications of each tool. in conclusion, each application requires a specific tool to generate and collect data. therefore, recommending one tool to select when working in an sdn network is not advisable, and the choice depends on the final goal of the work. acknowledgments this work is supported by the information and communications engineering department, alkhawarizmi engineering college, university of baghdad.   references [1] a. sha, s. madhan, s. neemkar, v. b. c. varma and l. s. nair, “machine learning integrated software defined networking architecture for congestion control,” in: 2023 inter-national conference on distributed computing and electrical circuits and electronics (icdcece), ballar, india, pp. 1-5, 2023, doi: 10.1109/icdcece57866.2023.10151339 . 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[21] http://mininet.org / [22] https://iperf.fr/iperf-doc.php [23] https://ryu.readthedocs.io/en/latest/ofproto _v1_3_ref.html [24] https://www.wireshark.org / [25] https://github.com/martimy/flowmanager ( 2025) 93-105، صفحة 2العدد، 21مجلة الخوارزمي الهندسية المجلد تبارك ياسين خضير 105  األدوات الحديثة للشبكات المعرفة بالبرمجيات توليد حركة المرور وجمع البيانات 2عمر علي عذاب *1تبارك ياسين خضير ، بغداد ، العراق جامعة بغداد ، كلية الهندسة الخوارزمي ،قسم هندسة المعلومات واالتصاالت 1،2 tabarak.taha1603@kecbu.uobaghdad.edu.iq االلكتروني:البريد * المستخلص قابلية التوسع والمرونة واألمان. وتعود هذه الميزة إلى sdnأثبتت الشبكات الُمعّرفة بالبرمجيات ) ( تفوقها في معالجة مشاكل الشبكات التقليدية، مثل م فيها وتحسين فصلها مستوى التحكم عن مستوى البيانات. ورغم أن العديد من الدراسات ركزت على إدارة الشبكات الُمعّرفة بالبرمجيات ومراقبتها والتحك أن القليل منها ركز على عرض ما يُستخدم لتوليد حركة المرور وجمع البيانات. كما تفتقر األدبيات إلى مقارنات بين األدوات واألساليب جودة الخدمة، إال بكات الُمعّرفة ة الش المستخدمة في هذا السياق. لذلك، تُقدم هذه الدراسة أحدث األدوات المستخدمة لمحاكاة وتوليد والحصول على إحصاءات حركة المرور من بيئ ومن ثم تحديد البيئة بالبرمجيات. باإلضافة إلى ذلك، تُقارن األساليب المستخدمة في جمع بيانات الشبكات الُمعّرفة بالبرمجيات الستكشاف إمكانيات كل منها، . تم openflowمع طوبولوجيا الشجرة ومفاتيح mininetالمناسبة لكل طريقة. تمت محاكاة منصة اختبار الشبكات الُمعّرفة بالبرمجيات باستخدام برنامج إلنشاء مجموعات بيانات الشبكة من أجهزة pythonونصوص pingو iperf3للتحكم في إعادة التوجيه. تُستخدم األدوات الشهيرة ryuتوصيل وحدة تحكم وعة البيانات وجمعها. تُظهر النتائج نجاًحا في توليد أنواع لمراقبة مجم ovs-ofctlوأمر ryuوتطبيق wiresharkُمحددة في الشبكة. يُستخدم برنامج األداة األمثل لتوليد البيانات للتحكم في iperf3متعددة من مقاييس الشبكة الستخدامها مستقبًًل في تدريب خوارزميات التعلم اآللي أو التعلم العميق. لذلك، يُعدّ أداة المراقبة األنسب للحصول على جميع ryuمفيدًا لتوليد البيانات للكشف عن هجمات رفض الخدمة الموزعة. تُعد تطبيقات pingاالزدحام، بينما يُعدّ الباحثين توليد تفاصيل الشبكة، مثل طوبولوجيا وخصائص وإحصائيات المكونات. كما تم استكشاف العديد من العقبات واألخطاء وسردها لتجنّبها عند محاولة بيانات في جهودهم العلمية القادمة. مثل هذه المجموعات من ال <4d6963726f736f667420576f7264202d20c7e1e4d3cec920c7e1e3e4d4e6d1c92033> al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 17, no. 2, june, (2021) p. p. 1830 the application of virtual reality to (mechatronics engineering) by creating an articulated robotic work cell using eon reality v9.22.24.24477 aiman al-allaq * nebojsa jaksic ** hussein al-amili*** dhuha mohammed mahmood**** *, ** colorado state university/ pueblo/colorad/ usa ***, **** al-khwarizmi college of engineering/ university of baghdad/ iraq *email: ah.alallaq@pack.csupueblo.com **email: n.jaksic@csupueblo.com ***email: alamilihussein@gmail.com ****email: duhamohammed55@gmail.com (received 10 november 2020; revised 1 march 2021; accepted 7 march 2021) https://doi.org/10.22153/kej.2021.04.001 abstract virtual reality, vr, offers many benefits to technical education, including the delivery of information through multiple active channels, the addressing of different learning styles, and experiential-based learning. this paper presents work performed by the authors to apply vr to engineering education, in three broad project areas: virtual robotic learning, virtual mechatronics laboratory, and a virtual manufacturing platform. the first area provides guided exploration of domains otherwise inaccessible, such as the robotic cell components, robotic kinematics and work envelope. the second promotes mechatronics learning and guidance for new mechatronics engineers when dealing with robots in a safe and interactive manner. and the third provides valuable guidance for industry and robotic based manufacturing, allowing a better view and simulating conditions otherwise inaccessible. keywords: eon, matlab, robotics, simulation, virtual reality. 1. introduction virtual reality can be described as the field of recreating three-dimensional images and textures using computer software that utilizes hardware capabilities. vr procedures offer truly important assignment representation that helps for arranging and reviewing robotic systems and function, for foreseeing mechanical activities, preparing mechanical frameworks administrators, and for a visual impression of non-noticeable occasions like contact powers in mechanical errands [1]. according to dos santos [2], utilizing virtual reality on professional robotics instruction and training will help in reinforcing tasks, improving the conception of images, narrowing the time spent on learning and education, and increasing the precision. at present, there are numerous vr advancement instruments, including world toolkit, vega, virtools and eon studio. age studio is more mainstream for its solid thorough capacity and perception [3]. 1.1 . eon virtual reality starting the system is to start the eon studio software. eon releases updates to their software frequently so there may be more than one version of the software installed on the computer. find the latest release of the eon studio in the program menu or on the desktop. the icon aiman al-allaq al-khwarizmi engineering journal, vol. 17, no.2, p.p. 1830 (2021) 19 should be similar to the image in figure 1 fig. 1. eon studio icon. start the eon studio by clicking the icon. figure 2 shows what the default eon studio layout looks like. fig. 2. default eon studio layout. some views support context-sensitive help. this means you can bring up the correct help page of a specific node/prototype by pressing f1 while the node/prototype is selected. the components view, simulation tree window, and property bar support context-sensitive help. the information that is displayed depends on which view you are in when you press the f1 key: • if you are on the nodes tab of the components window, pressing f1 will present a help page describing how to use the selected node. • if you are on the prototypes tab of the components window, pressing f1 will present a help page describing how to use the selected prototype. • if you are in the simulation tree window or the property bar, pressing f1 will present a help page describing the node and the fields found in the property bar for the selected node. another avenue for obtaining help is through the eon help window. this can be accessed by clicking the help topics button on the toolbar or by selecting help topics from the help menu. this opens the same window that is accessed using the f1 key. rather than opening a specific topic (based on what is selected), however, it opens the "home" page from which you can generate your own search based on keywords, or you can browse through the entire help system. when eon is opened, one can see several windows, each of which serves a certain function, those windows are classified as follows: • simulation tree window • components window (nodes or prototypes) • routes window • property bar there are also a number of windows of lesser importance (because they are used less frequently or used only in certain circumstances). these include: • local prototypes window • log window • find window • butterfly window additionally, there are numerous toolbars that put commonly used features and functionality in a convenient location for ease of use. figure 3 illustrates aiman al-allaq al-khwarizmi engineering journal, vol. 17, no.2, p.p. 1830 (2021) 20 many of these child windows and tools within the eon studio interface, in their default locations. fig. 3. eon studio default workspace. there are four basic types of windows in eon studio. they are: • construction windows • library window • help windows • simulation window an eon simulation is built by forming and connecting base node and prototype components together. this will create a certain function scheme that will produce a (or constructing) a simulation, and therefore it makes sense that some of the windows are viewed as "construction" windows. the construction windows are the simulation tree window and the routes window. the simulation tree window is where eon applications are built by arrangement nodes into subtree orders. each node is represented within that tree with an identifying text and a small icon. every hub has a property page that can be shown by double tapping the hub. the routes window is a realistic proofreader for characterizing intelligent, occasion driven connections between hubs. you characterize how data should be sent between hubs by making sequences between nodes. courses are made by hauling hubs from the recreation tree progression into the routes window, where the hub symbols are associated with lines or, all the more explicitly, courses. after hubs are associated, they can trade data or trigger occasions while the reproduction is running. 1.2 system components there are several different components that can comprise the eon software. the fundamental programming segments, which run on microsoft windows frameworks are: eon studio, eon dynamic load, eon sdk, and eon raptor. age studio is a finished graphical ui based creating device for growing constant 3d sight and sound applications zeroed in on deals/advertising, preparing/uphold [4, 5], and perception. the advancement cycle incorporates bringing in 3d objects, as a rule beginning from different demonstrating apparatuses like 3d studio max (otherwise called 3ds max) and light wave 3d, or from pc helped plan (cad) frameworks, for example, solid-works, archicad, or autocad. age studio can import information in various record designs. after the model is imported, practices can undoubtedly be related with the models through eon's instinctive graphical programming interface, reenactment tree, hub properties, occasion steering, scripting, or even accumulated c++ code, utilizing the eon sdk along with eon studio. the vicon tracking system is what tracks your movements as you aiman al-allaq al-khwarizmi engineering journal, vol. 17, no.2, p.p. 1830 (2021) 21 interact with the simulation. the system is comprised of the three tracking cameras that are mounted above the screen, the reflective balls mounted on the controllers and 3d glasses, and the vicon tracking software. this system has been calibrated so that the simulation will track the movements of the 3d glasses to determine the user’s position and perspective. it will also track the controller so the user can use it to interact with the simulation. double click the icon to start the vicon tracker software. figure 2 shows the interface to the vicon tracking software. opposite to what has been mentioned by crespo, garcía, and quiroz [6], this system and its application is simpler and uses less hardware and software addons, thus making it much more efficient in terms of ease of use, complexity, functionality, and even cost. 1hardware • vicon 3d laser tracking system. • tower workstation computer, 9th gen intel core i7, 32gb ddr4 ram, 1tb hdd, geforce gtx 1650 graphics. • wireless kb. 2process software • eon reality v9.22.24.24477. • autodesk 3d max. • eon raptor addon. these features make a wider range of opportunities of use in vast range of applications, such as in engineering education, manufacturing, and in the health sector. 2. implementation following what has been previously stated. the implementation of the application followed the structure of the available system components as can be seen in figure 4 below. starting with the cad model of the chosen robotic arm, the model was of a six-axis articulated robotic arm. the arm was constructed first autodesk 3d max. the model was then imported to eon raptor. eon raptor is a 3d max plug-in tool that allows for simple interaction and manipulation of cad models. some interactions can be performed within 3d max. the completed application models can then be exported and imported to eon for further modification, the models are exported as .eoz files. once the model is imported to eon, it can be seen in eon application tree with the main scene frame, this allows for the addition and modification of the imported model with the main frame of the application. for the robotic arm, several node interactions are needed to establish the relationship between the imported model parts and define the model relationship with the scene environment. several node properties are depended upon the robotic arm forward and reverse kinematics calculations, which are solved separately using matlab software. after the node properties are set, and the range of each link within the cell work envelope is properly simulated. physics nodes are introduced to finalize the application and its node interactions within a realistic frame that is depended upon real physical properties introduced by physics node. each frame within the robotic arm model and the whole environment scene will be provided with its own physics node that reflects its real physical properties. the resulting physics interaction between the frames will be verified and the adjusted accordingly until a suitable result is obtained. a suitable result is one where the model interaction and node simultaneous properties (such link weight, position, and speed) matches what is analytically expected. lastly, the final model gui menu is designed and then built. a teach pendant of what most robotic arms available have, and contains most the of intuitive functions, such as link selector, axis movement direction and speed. this is followed by designing the final application interface window. in conclusion, the finished application can be exported either as standalone application, web-based application, advanced vr display systems, and/or imbedded systems. aiman al-allaq al-khwarizmi engineering journal, vol. 17, no.2, p.p. 1830 (2021) 22 prepare the robot cad model import the model to eon raptor get an .eoz model set the node properties to fit the requirements incoporate the approparate nodes link interactions import the model to eon pro perform model/ node interaction and programming integrate physics nodes into the model build model gui purplish and export finished eon vr model get the required textures for the environment build the application scene settings fig. 4. eon application process flow. 2.1 . modeling the cad model of the six-axis robotic arm was the first step in the process of building the virtual reality application. the model was of a sixaxis articulated robotic arm. robots have various axis configurations. by far most of verbalized robots, notwithstanding, highlight six tomahawks, likewise called six levels of opportunity. six hub robots take into consideration more prominent adaptability and can play out a more extensive assortment of utilizations than robots with less tomahawks. axis 1 this pivot, situated at the robot base, permits the robot to turn from left to right. this broad movement stretches out the work territory to remember the region for one or the other side and behind the arm. this pivot permits the robot to turn up to an entire 180 degree range from the middle point. axis 2 this pivot permits the lower arm of the robot to stretch out forward and in reverse. it is the hub controlling the development of the whole lower arm. axis 3 the pivot broadens the robot's vertical reach. it permits the upper arm to raise and lower. on some expressed models, it permits the upper arm to reach behind the body, further extending the work envelope. this hub gives the upper arm the better part access. axis 4 working related to the hub 5, this hub helps in the situating of the end effector and control of the part. known as the wrist move, it pivots the upper arm in a round movement moving parts between level to vertical directions. axis 5 this pivot permits the wrist of the robot arm to tilt here and there. this pivot is answerable for the pitch and yaw movement. the pitch, or twist, movement is all over, much like opening and shutting a crate top. yaw moves left and right, similar to an entryway on pivots. axis 6 this pivot permits the wrist of the robot arm to tilt here and there. this pivot is answerable for the pitch and yaw movement. the pitch, or twist, movement is all over, much like opening and shutting a crate top. yaw moves left and right, similar to an entryway on pivots. following that, the general robotic arm concept was then molded in autodesk 3d max. many industries use 3ds max for generating graphics that are mechanical or even organic in nature. the engineering, manufacturing, educational, and medical industries all make use of 3ds max for visualization needs as well. 3ds max utilizes polygon displaying which is a typical method in game plan. with polygonal displaying craftsmen have a serious level of authority over individual polygons which gives them a more noteworthy scope of detail and exactness in their work. after a model is finished, 3ds max would then be able to be utilized to produce the materials and surfaces important to truly rejuvenate things. adding surface subtleties, for example, shadings, slopes, and surfaces will prompt greater delivers and game resources.. 2.2 . import to eon the model was then imported to eon raptor. eon raptor permits to show and associate 3ds max content in real time and with natural controls. the completed application models can then be exported and imported to eon for further modification, the models are exported as .eoz files. once the model is imported to eon as shown in figure 5, it can be seen in eon application tree with the main scene frame, this allows for the aiman al-allaq al-khwarizmi engineering journal, vol. 17, no.2, p.p. 1830 (2021) 23 addition and modification of the imported model with the main frame of the application. for the robotic arm, several node interactions are needed to establish the relationship between the imported model parts and define the model relationship with the scene environment. several node properties are depended upon the robotic arm forward and reverse kinematics calculations, which are solved separately using matlab software. fig. 5. cad model imported into eon. 2.3 . robot kinematics 2.3.1 forward kinematics modeling for the robot arm model used in eon application. forward kinematics is the transformation between joint space and the cartesian space to solve the position and orientation of the robot end effector. denavit hartenberg (dh) convention computes the forward kinematic by attaching a coordinate frame system at each joint and specifying the four parameters of dh: αi-1, ai-1, θi and di where: ai: (link length) is the distance between zi-1 and zi axes along the xi axis. αi: (link twist) is the required rotation of zi-1 to zi axes about the xi axis. di: (joint offset) is the distance between xi-1 and xi axes along the zi-1 axis. θi: ( joint angle) is the required rotation of xi-1 to xi axes about the zi-1axis. the transformation matrix of frame {i} relative to previous frame {i-1} is: 0 0 0 0 1 i i i i i i i i i i i i i i i i i c s c s s a c s c c c s a s s c d θ θ α θ α θ θ θ α θ α θ α α −    −        ...(1) and the transformation matrix of nth coordinate frame to base coordinate frame is: 0 0 1 1 1 2 ....n n n t t t t − = ... (2) the first (3x3) matrix represents rotation matrix of frame {i} relative to frame {i-1} and the fourth column represents the origin of the frame {i} position in frame {i-1}. dh parameters of the robot manipulator are defined according to the assigned frames that shown in fig.2 and they are listed in table 1. aiman al-allaq al-khwarizmi engineering journal, vol. 17, no.2, p.p. 1830 (2021) 24 fig. 6. the attached coordinate frame systems for eon robot model table 1, dh parameters of the eon robot manipulator i ai (mm) αi (deg) di(mm) ѳi 1 0 90 201 q1 2 390 0 65 q2 3 0 90 -65 q3 4 0 -90 380 q4 5 0 90 0 q5 6 0 0 81 q6 2.3.2 inverse kinematics the reverse kinematics issue of the chronic controllers has been read for a long time. it is required in the control of controllers. illuminating the opposite kinematics is computationally sweeping and by and large takes quite a while in the continuous control of controllers. undertakings to be performed by a controller are in the cartesian space, while actuators work in joint space. cartesian space incorporates direction network and position vector. be that as it may, joint space is spoken to by joint points. the change of the position and direction of a controller end-effector from cartesian space to joint space is called as reverse kinematics issue. there are two arrangements approaches in particular, mathematical and arithmetical utilized for inferring the converse kinematics arrangement, logically. 2.3.3 kinematic jacobian jacobian gives the relationship between the joint’s velocities and the corresponding end effector linear and angular velocities. the end effector linear and angular velocities can be defined as: )1()6()16( nxxno p xe e q j jv               =      & ω ...(1) where: ve : (3×1) matrix represents the end effector linear velocity in cartesian space. ωe : (3×1) matrix represents the end effector angular velocity in cartesian space. jp : (3×n) jacobian matrix relates the end effector linear velocity to joints velocities. jo : (3×n) jacobian matrix relates the end effector angular velocity to joints velocities. the geometry ith column of jacobian matrix for revolute joint is:       −× =      − −− 1 11 )( i iei o p z ppz j j i i ...(2) where: zi-1: unit vector in z-direction is given by third column of the rotation matrix 0 1−i r . pe: end effector position vector is given by the first three elements of fourth column of transformation matrix 0 e t . pi-1: is given by the first three elements of the fourth column of transformation matrix 1−i i t . these calculations helped in the following steps in eon modeling. where the values calculated used to determine the range of movement for each link and will be used in the nodes used in eon. 2.4 nodes interaction simulations are implicit eon studio, yet you will require different projects to make and alter 3d items, surfaces, and sounds. albeit some fundamental item altering is conceivable inside eon studio (for instance, you can change an article's tones or apply various surfaces), the "crude materials" needed for your reenactments, for example, 3d models, surfaces, and sound records, must be set up ahead of time. building an eon recreation includes four principle activities: adding (bringing in) math to a scene and sorting out the scene chain of importance applying materials and improving 3d objects in a scene characterizing conduct properties for these items indicating how clients will interface with objects in the recreation figure (7) shows hubs window. to additional improve the aiman al-allaq al-khwarizmi engineering journal, vol. 17, no.2, p.p. 1830 (2021) 25 authenticity of a reproduction scene, you may likewise need to add sound, lighting, and embellishments. the last advance in the process is dispersing the application. most eon applications are planned to be shown outside of eon studio. since eon clings to microsoft's activex standard, you can see full-include eon applications in archives made in activex-agreeable projects fig. 7. nodes window. probably the most effortless ways for the client to interface with a recreation is by utilizing the mouse. with essential methods, the simulation can be configured so that users can navigate through the simulation environment and manipulate simulation objects by moving and clicking the mouse. you can also add more complex interactions that will enhance the user's experience with the simulation. in eon, nodes such as mesh2, texture2, and movietexture use external resources. these nodes have a field named embedded that indicates whether the resource is to be placed inside or outside the resulting distribution file. the embedded flag has no effect on project files (.eoz or .eop) because all resources except dynamic prototypes are always embedded in the project files. however, when creating distribution files, the resources that are marked as external (embedded = false) will be placed outside of the distribution file. these resources will be compiled like the embedded ones, but, as mentioned previously, they will be placed in a subfolder relative to the distribution file. figure 8 shows the nodes interaction window. an item's situation in 3d space is controlled by its interpretation and revolution esteems. interpretation alludes to development along a hub a positive or negative way and is communicated in (x, y, z) values. on the x axis (right to left}, positive is to the right and negative is to the left. on the y axis, a positive coordinate is into the screen also, a negative facilitate is out of the screen. on the z hub, positive is up and negative is down. aiman al-allaq al-khwarizmi engineering journal, vol. 17, no.2, p.p. 1830 (2021) 26 fig. 8. nodes interaction. rotation refers to rotation around an axis and is communicated in h, p, and r esteems, speaking to heading, pitch, and roll. heading (h) is the revolution around the z pivot, pitch (p) is the turn around the x hub, and move (r) is the turn around the y hub. revolution is indicated in degrees inside the 0° to 360° territory. a section of 90° is likewise substantial and is dealt with equivalent to 270°. in the event that you had the option to remain at the beginning of the facilitate framework and sight along the different interpretation tomahawks, you would experience positive rotation in a counterclockwise direction. figure 9 shows nodes properties window. fig. 9. nodes properties the keymove node is an extremely useful node for simulation development. it provides an easy way to place an object correctly in the 3d world while the simulation is running. this allows aiman al-allaq al-khwarizmi engineering journal, vol. 17, no.2, p.p. 1830 (2021) 27 you to visually position your model exactly where it should be and then determine the exact coordinates for that position-in translation (the position property in eon) and rotation (the orientation property in eon). the click sensor allows you to cause action to happen when an object is clicked on by either the right or left mouse button. the following example will demonstrate the use of the click sensor node. the rotate hub pivots its parent around one hub (x, y, or z) or a mix of these. the beginning for the revolution is the rotate point characterized by parent hub, typically an edge. the parent hub must help turn. turn is indicated by three qualities (x, y, or z). these decide the portion of a 360° turn around the individual pivot to be finished during the laptime esteem. the laptime value is specified by the number of seconds it takes to make one rotation. 2.5 physics interaction the eon professional physics module gives admittance to highlights like gravity, mass, contact, kinematics and actual requirements between objects. the physics module is based on the effective vortex material science motor that is a ground-breaking elements motor, in view of principal newtonian physical science. it additionally incorporates another hearty impact identification calculation with huge speed upgrades just as a high-constancy vehicle elements motor. we will now cover the various physics related nodes in eon professional and how they are used. the physics manager defines an independent physics world and have properties that affect all physics entities in that world. physics entities managed by different managers cannot interact with each other. it is best to only have one physics manager per simulation to avoid conflicts. most of the time you do not have to add a manager since physics entities automatically create and connect to a manager when you add them to the simulation. the manager will be created in simulation/scene/managers. the physics manager node controls some of the high-level physics parameters for the simulation. the main parameter that will be adjusted will be the force of gravity. the rigidbody node defines an object as a rigid body and hold physical properties such as mass and volume. as opposed to deformable objects, they do not change their shape during the simulation. a rigid body can be static, kinematic or dynamic. • dynamic – is affected by gravity • kinematic – can be move other objects. • static – will not move rigid body dynamics enable objects to move realistically when influenced by forces, joints or the interaction with other rigid bodies. to define an object as a dynamic rigid body, put a rigidbody node in the frame that represent the object. the geometries in the object frame will be used to generate collision geometry for the rigid body. by default, convex collision geometries will be generated for each geometry. the type of collision geometry to generate can be specified in the geometrytype field. it is important to choose the appropriate geometry type for you object so you do not use. the box type uses a lot less processing power than the triangle mesh. the charactercontroller node provides the standard collide and slide character behavior that is often used in games. the charactercontroller makes it possible to walk on the ground, climb stairs and small obstacles and slide along walls. the charactercontroller geometry approximate a character as an upright cylinder with a rounded top and bottom. the name character controller is a bit misleading; it is not really controlling the character, it detects and handles collisions. when using a charactercontroller, a rigidbody or collisionobject is also needed to define the collision geometry that the character will interact with. a typical use is to make the camera a controlled character, put a charactercontroller node in the camera and a collisionobject node in the frame with the environment geometry and it will be possible to walk around in the environment in a first-person view. 2.6 gui design the main focus was to what the vr application users might need to do and ensuring that the interface has elements that are easy to access, understand, and use to facilitate those actions. users have become familiar with interface elements acting in a certain way. doing so will help with task completion, efficiency, and satisfaction. there are times when multiple elements might be appropriate for displaying content. provide 2d graphical user interface (gui) elements that overlay the 3d simulation window. they are positioned with 2d pixel screen coordinates. because they are not part of the 3d space, they do not render inside a viewport. it does not matter what frame they are placed in because they will behave the same regardless of where they are. this lesson will cover the three most common 2d gui control nodes. the aiman al-allaq al-khwarizmi engineering journal, vol. 17, no.2, p.p. 1830 (2021) 28 2dtext2 node displays text wherever you want in a box whatever size you want and with whatever colors you want. the text can be updated constantly to show real-time data if you want. figure 10 shows what the default 2dtext2 node looks like. fig. 10. 2dtext2 node. one important thing to note for many of the guicontrol nodes is that there are position/size and position/size offset fields. you specify the position parameter as a percentage of the screen. you specify the position offset as number of pixels. if you want the node to scale with the window use the position/size fields. if you want the nodes to stay the same size regardless of the size of the simulation window use the offset fields. don’t use both fields at the same time; i.e. if you use position make sure the offset field is “0 0” and if you use the offset field make sure the position is “0 0”. it is usually best to use the position/size field instead of the offset fields for the 2dtext2 node. 3. simulation before the final simulation. the application structure can be seen in the tree window, and by expanding the scene frame, one can notice the order and the structure of the frames and nodes under the scene frame. since the model for the robot arm was imported, the resources group was automatically created with materials, textures, and meshes folders. the user will have the option to use the gui interface or use eon intuitive controls. running the simulation by clicking the simulation button on the menu bar and getting the simulation window. a right-click and holding the mouse while dragging upward, this allows the user to zoom out and downward to zoom in. pressing ctrl and shift at the same time (or, alternatively, pressing p). this will display the x, y, and z axes for the simulation. a leftclick and moving the mouse to rotate and pivot around the robotic arm to view it from different angles. clicking the robotic arm and then use the x, y, z, h, p, and r keys with the up and down arrow keys allows for the verification that each part of the arm is moving correctly. the addition of clickseneor and different rotation nodes (dragging and dropping these nodes under the dof node located under the selected robotic arm frame) gives the functionality of allowing the user to click on the robotic link on the simulation screen and then use the gui to perform the required action as shown in figure 11. following this logic, all the robot links can be actuated to perform user functions. as compared to the work in [7, 8], the work described here is technically less complicated, in terms of the modules and addons used, programming approach, and ease of application. fig. 11. system application. aiman al-allaq al-khwarizmi engineering journal, vol. 17, no.2, p.p. 1830 (2021) 29 4. conclusions a virtual reality of 6-axes robotic has been implemented. the presented system is fully configurable, expandable and immersive. based on the obtained results and tests, it can be determined that the application has a high potential to become a very reliable engineering learning tool. the system is fully functional and it is presented in a stage from which it can be modified. learning users can make use of the virtual reality system and interact with it, chances to make mistakes are allowed, since simulation prevents user or equipment damage. 5. references [1] l. pérez, e. diez, r. usamentiaga, and d. f. garcía, "industrial robot control and operator training using virtual reality interfaces," computers in industry, vol. 109, pp. 114120, 2019/08/01/ 2019. [2] m. c. c. d. santos, v. a. sangalli, and m. s. pinho, "evaluating the use of virtual reality on professional robotics education," in 2017 ieee 41st annual computer software and applications conference (compsac), 2017, vol. 1, pp. 448-455. [3] c. v. hurtado, a. r. valerio, and l. r. sánchez, "virtual reality robotics system for education and training," in 2010 ieee electronics, robotics and automotive mechanics conference, 2010, pp. 162-167. [4] f. wang, "research on virtual reality based on eon studio," in 2010 fourth international conference on genetic and evolutionary computing, 2010, pp. 558-561. [5] j. he and w. hou, "key technologies of the virtual driving platform based on eon," in 2011 international conference on virtual reality and visualization, 2011, pp. 263-266. [6] r. crespo, r. garcía, and s. quiroz, "virtual reality simulator for robotics learning," in 2015 international conference on interactive collaborative and blended learning (icbl), 2015, pp. 61-65. [7] j. feuser, o. ivlev, and a. graser, "collision prevention for rehabilitation robots with mapped virtual reality," in 9th international conference on rehabilitation robotics, 2005. icorr 2005., 2005, pp. 461-464. [8] b. volmer, a. verhulst, a. drogemuller, b. h. thomas, m. inami, and m. sugimoto, "towards robot arm training in virtual reality using partial least squares regression," in 2019 ieee conference on virtual reality and 3d user interfaces (vr), 2019, pp. 1209-1210. ،2ا���د ،17ا� ��� ا������ ا���ارزم� �� م ا� ا���ق ��� 30 -18 )2021( 30 �48%��ام ذراع رو�8ت2 6ج ا� �41-$و012) " ط$�* -,+�* ا��ا() ا'&%$ا#� "�! 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ا+6و%!2tت %j$6c& آ)?& و2mt\"'&. وا+2p+[ $!6f إر2wدات l"+ &:'h?2\& وا+g'?l9 ا+kl2j \"] ا+6و%!ت، ):u:v$ 2 %6ؤ$& .2ا+6zوف ا+9; $19^ر ا+!s!ل إ+'@ this is an open access article under the cc by license al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 19, no. 3, september, (2023) p. p. 4455 high transaction rates performance evaluation for secure egovernment based on private blockchain scheme osama ibraheem kadhm* ali hussein hamad** *,**department of information and communications/al-khwarizmi college of engineering/ university of baghdad/baghdad/iraq corresponding author *email: ooosaamaa84@gmail.com **email: ahamad@kecbu.uobaghdad.edu.iq (3202 unej 18 accepted; 3202 archm 41 received) 2.006.0320https://doi.org/10.22153/kej.2 abstract the implementation of technology in the provision of public services and communication to citizens, which is commonly referred to as e-government, has brought multitude of benefits, including enhanced efficiency, accessibility, and transparency. nevertheless, this approach also presents particular security concerns, such as cyber threats, data breaches, and access control. one technology that can aid in mitigating the effects of security vulnerabilities within egovernment is permissioned blockchain. this work examines the performance of the hyperledger fabric private blockchain under high transaction loads by analyzing two scenarios that involve six organizations as case studies. several parameters, such as transaction send rate, blockchain size, batch timeout, organization number, and the number of clients, were modified in the two scenarios. the gradual addition of organizations was also observed to determine the impact of multi-organization on the throughput, latency, and scalability of the system. by increasing the block size to approximately 100 transactions per block, acceptable performance and latency results are attained. the throughput and latency findings are accepted for three or four organizations, but when many organizations are added, throughput and latency begin to suffer from poor performance. also, many tests show that increased block timeout for high sending rates positively affects the throughput and latency. keywords: e-government, private blockchain, fabric, hyperledger caliper, performance analysis. 1. introduction information and communications technology (ict) developments have totally changed how governments interact with the people they govern and offer services. e-government has made it possible for citizens to conveniently access government services and information online, anytime, from anywhere, and without having to physically visit government offices [1,2]. this change has resulted in increased transparency, accountability, and citizen involvement while also considerably improving accessibility, convenience, and efficiency in government services. e-government has also resulted in lower administrative expenses, higher productivity, and an overall improvement in the quality of public services. the expansion of e-government is anticipated to continue and bring about additional changes in how governments function and engage with their citizens as digital tools and platforms become more widely accessible [3]. the main goals of e-governments are to streamline and enhance the processes of the governments in order to increase accessibility and effectiveness for both citizens and business while using government services and carrying out transactions. by increasing public awareness of government activities, e-government has an opportunity to strengthen openness and mailto:ooosaamaa84@gmail.com mailto:ahamad@kecbu.uobaghdad.edu.iq https://doi.org/10.22153/kej.2023.06.002 osama i. kadhm al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 4455 (2023) 45 accountability [4]. this can be done by improving access to public records, publishing government data and information online, and allowing individuals to follow the development of government projects and activities. additionally, e-government initiatives can stimulate economic growth by supporting corporate growth and enticing investment. one noteworthy instance is the simplification of procedures for registering and approving businesses, which can help create a climate more conducive to business expansion [5]. despite the many services the electronic government provides, but some people are afraid to use it because of security problems that egovernment faces, including identity theft of sensitive personal data by hackers. also, egovernment systems are vulnerable to cyberattacks which can steal the information stored in secured systems by compromising them. cyberattacks can come in many forms, including phishing, ransomware, and denial-of-service attacks. technical problems with e-government systems can also make people hesitant to use them [6]. the security of e-governments can be strengthened by many technologies. these include cloud computing, biometric authentication, multifactor authentication (mfa), public key infrastructure (pki), and blockchain technology [7]. blockchain technology is a system of distributed digital ledgers for transactions that are computer-based. if the block is a part of the chain, it cannot be changed or deleted. a history of transactions is kept in each block of the chain. as a result, all transactions on the blockchain are transparent and permanent [8,9]. the technology behind the blockchain is based on cryptography and decentralized consensus. each node in the network has a copy of the blockchain, and each node must validate and agree on each transaction before it is added to the chain. this consensus mechanism ensures that the blockchain is secure, transparent, and tamper-proof [10,11]. the bitcoin blockchain, a decentralized database for bitcoin transactions, is the most well-known application of blockchain technology. yet, blockchain technology has a wide range of uses outside of cryptocurrencies, such as supply chain management, electoral processes, and digital identity confirmation. with blockchain technology, e-government security could be increased in several ways, including the ability of blockchain to produce an unchangeable transaction history; that is, a transaction that has been added to the blockchain cannot be altered or deleted once it has been added [12,13]. this paper aims at contributing in the development of a secure and efficient egovernment system using hyperledger fabric blockchain technology with high transaction rates reaching 200 tps. also, it discusses the scalability and performance of the system by engaging six organizations with up to 150 clients. this paper assesses the performance of fabric blockchain by evaluating transaction latency, parallel throughput, and scalability under varying blockchain sizes, batch timeouts, clients, and organizations with a transaction rate of 200 tps. the work includes six fabric firms and benchmarks fabric performance with the caliper. the rest of this paper is structured as follows: section 2 presents the related work. section 3 explains hyperledger fabric permissioned blockchain, and section 4 details a multiorganization system with several experiments. also, the performance evaluation and analysis of private blockchains are described in this section. finally, section 5 presents the conclusions. 2. related work because of the essential role of the blockchain technology in developing new algorithms, a growing number of researchers have recently shifted their focus to its evaluation and analysis. an empirical study comparing the capabilities of hyperledger fabric and ethereum, two of the most notable blockchain platforms has been carried out by m. dabbagh and colleagues [14]. their performance was measured using four criteria: success rate, average latency, throughput, and resource usage. the results of performing one hundred transactions demonstrated that when compared with ethereum across all four performance measures, hyperledger fabric is superior overall. c. wang and x. chu [15]. investigated the performance characteristics of the hyperledger fabric at each step, including the execute, order, and validate phases. in addition to that, they investigated the ordering services, such as solo, kafka, and raft. the findings of their experiments revealed that the execution phase exhibited a robust scalability when the or endorsement policy was used, but this was not the case when the and endorsement strategy was used. they also discovered that the validation phase was likely to be the system bottleneck because of the osama i. kadhm al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 4455 (2023) 46 slow validation speed of the chaincode. this was another finding that they made. an investigation into the functionality and scalability of major private blockchain platforms, such as ethereum, quorum, corda, and hyperledger fabric, was carried out by a. a. monrat et al [16]. in order to evaluate each of these platforms, they first changed the workloads and then determine the performance evaluation metrics using throughput and network latency. the caliper tool was used in the test that saeed et al. [17] conducted to examine the effect of the electronic voting workload on the hyperledger fabric framework. this test looked at a variety of factors, including latency and performance. a great variety of alternative scenarios could be simulated and tested by making simultaneous changes to the transaction transmission speeds, block sizes, timeouts of the block, and organizations. caliper was utilized by w. choi and j. w. -k. hong [18] in order to conduct an analysis of an ethereum private network in addition to the ropsten testnet. according to their tests and comparisons, the ethereum private network performs superior to that of the ropsten testnet. in addition, the findings demonstrated that the results of the transactions could vary depending on the content of the transaction. using a hyperledger fabric goleveldb (hlf-gldb) benchmark allowed t. nakaike et al [19] to assess the performance of database systems that are employed in hyperledger fabric for discovering areas of optimization. as a standalone benchmark is used for simulating database accesses in hyperledger fabric, they developed hlf-gldb. the findings of their studies indicated that the data compression feature of goleveldb is a significant performance barrier in hyperledger fabric. turning off the data compression feature resulted in 54% improvement in the system's overall performance. they also discovered that the size of a database substantially impacts its performance; specifically, they observed that the performance decreased by 25% when the size of the database was raised by a factor of four. in summary, references [14] and [17] were the closest to our work. in reference [14], there are many differences between their work and ours. firstly, their work was limited to a maximum of 100 tps and only involved three organizations. in contrast, our work focused on higher transaction rates of up to 200 tps and included up to six organizations. secondly, while they relied solely on the block size of the blockchain, we also considered the block timeout, which is crucial for platform performance and scalability. lastly, their approach used the oring raft algorithm, which only required the agreement of one organization to confirm a transaction. in contrast, we utilized a more secure anding algorithm that requires the agreement of all organizations before a transaction can be confirmed. reference [17], their research focused on the e-voting process. additionally, they included up to three different organizations with fewer clients (under 20). what makes our work unique is that, in order to show the scalability and performance of our system, we tried to involve more organizations (up to six) and clients (up to 150). 3. hyperledger fabric platform hyperledger fabric is an open-source permissioned blockchain framework that aims at creating enterprise-grade distributed ledger technology for business applications. it allows developers to create smart contracts and applications using a modular architecture. hyperledger fabric is a unique blockchain platform designed for use cases where privacy, scalability, customization, and performance are critical. the fabric allows organizations to control who has access to their data and provides a range of privacy-enhancing features such as private channels, private data collections, and identity management [20,21]. hyperledger fabric is highly scalable in addition it can support many transactions per second. it achieves this through its unique approach to consensus, which allows for parallel transaction processing and off-chain data storage [22]. the membership service provider (msp), fabric certificate authority (ca), peer nodes, ordering service, chaincode, ledger, consensus protocol, and fabric software development kit (sdk) are among the major components of hyperledger fabric [23,24]. the msp is essential for handling and confirming network users' digital identities, including clients, peers, and orderers, in the hyperledger fabric ecosystem. its main job is to make sure that none except trusted and authorized parties can access the shared ledger or connect with other network members. for users of networks, the certificate authority (ca) acts as a reliable provider of digital identities, facilitating safe exchange of osama i. kadhm al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 4455 (2023) 47 information and transactions. its primary duty is to create and maintain digital certificates that verify network users' identities and protect transaction secrecy, integrity, and nonrepudiation. contrarily, the ordering service is vital to reaching an agreement and preserving the sequence of transactions among all nodes. transactions are received from clients and disseminated to all nodes by the system. then, using a consensus mechanism, it groups these transactions into blocks and puts them in a particular order. the ordering service offers the blocks to all network peers for validation and execution once they have been appropriately ordered. the chaincode works as a set of rules directing the network's operation. its goal is to simplify a range of network functions, including the execution of smart contracts, allowing for the execution of transactions and the accompanying record changes. the ledger, on the other hand, is comparable to a large record book that carefully documents and keeps a complete log of all transactions taking place within the network. it's shared by everyone in the network and can't be changed once something is written down. the fabric sdk is a toolkit that enable developers to interact with the network, submit transactions, and look at the ledger. consensus protocols ensure that everyone in the network agrees on what transactions happened and in any order. this helps to ensure that everything is fair and transparent. all of this makes the network secure, transparent, and auditable. figure 1 shows the basic flow diagram of the fabric platform. 4. proposed multi-organization system six interconnected organizations will conduct performance tests on the hyperledger fabric platform using the latest release of the software with long-term support, v2.4 (lts). the primary objective is to determine how various configuration settings, such as the block size, block timeout, number of clients, and number of organizations influence the throughput, latency, and scalability of the platform. as showed in figure 2, each organization has one fabric sdk through it, the clients can communicate with other entities in the fabric platform. one ca which is responsible for granting certificates to members, one msp tasked with keeping track of authorized entities. each organization also has one committer which commits the transaction to the ledger, and one anchor peer which is responsible for communications with the other organizations. besides, all the organizations are connected to one orderer node which depends on a raft algorithm and is responsible for maintaining the order and consistency of transactions on the blockchain. fig. 1. basic flow diagram of hyperledger fabric [6]. osama i. kadhm al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 4455 (2023) 48 hyperledger caliper is a tool that can evaluate and verify the performance of various hyperledger platforms, including the fabric by measuring metrics such as latency, throughput, and scalability. in this work, we have configured the following options: a transaction rate of 200 tps, serving clients ranging from 1 to 150, and block timeouts set at 1 second, 2 seconds, and 5 seconds. the design shown in figure 2 distinguishes itself from other designs in multiple ways. firstly, it incorporates six distinct organizations, whereas conventional designs usually involve up to three organizations. using six organizations provides more robust proof of scalability for the platform compared to three organizations. secondly, this design can accommodate up to 150 clients or even more, a significant increase compared to other designs that typically cater to fewer than 150 clients. thridly, we have relied on two factors the block timeout and the block size to improve the performance and scalability of the system. in contrast, other implementations only rely on the block size. finally, we are able to achieve transmission rates of 200 tps, while other designs only reached 100 tps. to test the system's throughput, latency, and scalability, we have employed the following two scenarios in this work: fig. 2. multi-organization scheme. 4.1 scenario one: varying the block size of the blockchain. three rounds of testing have been done in this scenario to gauge the system's throughput and typical latency. a total of 10,000 transactions are included in each round. the maximum sending rate we achieved in this test with the caliper is set to 200 transactions per second in all rounds, with the block size increasing from (50, 100, and 150) transactions per block and the number of clients increasing from 50 to 100 and 150 in each round. the batch timeout's default setting was 2 seconds. as shown in figure 3(a), when the sending rate is set to be 200 tps and the block size to 50 (tx/block), the throughput was acceptable on the first three organizations, especially with a small number of users in the system, which was about 70 tps for 50 clients, about 57 tps for 100 clients, and about 30 tps for 150 clients. but with increasing number of organizations to six and osama i. kadhm al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 4455 (2023) 49 number of clients to 150, the throughput dropped sharply until it reached only 6 or 7 tps. the case is the same for latency, as shown in figure 3(b). that is, for the first three organizations and few clients, the latency was good which reached about 6 seconds, but when the number of organizations increases to six and the number of clients increases to 150, the latency becomes very high (about 45 seconds). figure 3(c) and 3(d) shows that the increase of the block size to 100 (tx/block) had better impact on the throughput and latency. the throughput increased to about 75 tps at three organizations and 50 clients, about 63 tps for 100 clients, and about 40 tps at 150 clients. but from experiments, we found that when the block size increased to 150 (tx/block). this increase negatively impacted the throughput and latency, as shown in figures 3(e) and 3(f); the throughput declined to about 54 tps at 50 clients and 3 organizations, about 50 tps at 100 clients, and about 30 tps at 150 clients. the experiments also show that under full load includes engaging all six organizations and 150 clients; the throughput and latency results of block size = 50 were about 7 tps and 47 seconds as shown in figures 3(a) and 3(b). while the throughput increaed to about 10 tps and the latency decreased to about 45 seconds at block size = 100, as in figures 3(c) and 3(d). also, at block size = 150 (tx/block) the throughput decreased to about 6 tps and the latency increased to about 50 seconds as in figures 3(e) and 3(f). the experiments described above show that the optimal combination of throughput and latency was achieved using 100 transactions per block size. therefore we will depend on 100 (tx/block) in the next scenario. 4.2 scenario two: varying the blocking timeout of the blockchain. three rounds of testing have been done in this situation as well to gauge the throughput and latency of the system. ten thousand transactions are included in each round. because this block size produced the most significant results in scenario one, we have fixed the block size to 100 transactions per block for all rounds. the blocking timeout is then increased from (1, 2, and 5) seconds for three experiments. after that, we increased the number of clients in each round from 50 to 100 and 150 in all six organizations. next, we set the sending rate to 200 tps, which is the maximum rate we have reached in this experiment with the caliper. figures 4(a,c) demonstrate that the throughput was enhanced when we increased the blocking timeout from 1 second to 2 seconds; that is, under heavy load, which includes engaging all six organizations and 150 clients, the throughput was about 5 tps at 1 second timeout and about 11 tps at 2 seconds. while the throughput reached its maximum level (about 20 tps) when the blocking timeout is increased to 5 seconds, as in figure 4(e). regarding the latency (also under heavy load, which includes engaging all six organizations and 150 clients), figures 4(b,d) show that the latency decreased whenever the blocking timeout was increased from 1 second to 2 which was about 56 seconds at timeout = 1 second and about 45 seconds at 2 seconds timeout. also figure 4(f) shows that the latency decreased to its lowest level (about 39 seconds) when we increased the blocking timeout to 5 seconds. the block timeout reduction suggests that the block was cut before it had reached its maximum capacity. the findings showed that increasing block timeout better impacts system performance, particularly with big block sizes. while increasing the batch timeout may seems like a straightforward way to address a slow network or high latency issues, it can come with some disadvantages. a higher latency improves the likelihood of including more transactions in a single block. the size of a block expands in proportion to the number of transactions in it. larger block sizes can lead to more extended propagation and validation times, increasing the likelihood of network congestion and reducing the overall network throughput. also, the consensus mechanism in hyperledger fabric requires that all nodes in the network agreemet on the order of transactions. osama i. kadhm al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 4455 (2023) 50 3.a 3.c 3.e 3.b 3.d 3.f fig. 3. (a,b,c,d,e,f). throughput and latency results of increasing the block size. some nodes could become out of synchronization with the rest of the network if the batch timeout is configured too high. lower consensus efficiency could come from this, affecting the network as a whole. osama i. kadhm al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 4455 (2023) 51 4.a 4.c 4.e 4.b 4.d 4.f fig. 4. (a,b,c,d,e,f). throughput and latency results of increasing the block timeout. osama i. kadhm al-khwarizmi engineering journal, vol. 19, no. 3, p.p. 4455 (2023) 52 5. conclusions  in this research, we investigate how a workload generated by a multi-organizational system affects the functionality of a blockchain running on the hyperledger fabric platform. we have concentrated on evaluating the average latency, scalability, and throughput parameters. we did various tests to undertake our analysis, varying parameters including transmission rates, block sizes, block timeouts, client count, and overall organization count. in the end, we found that the complexity of the smart contracts, the hardware configuration, and the design of the blockchain network all contribute to its success. our findings have revealed the following results in greater details: 1we found an intriguing correlation between block timeout, block size, and the performance os the system. we specifically saw improvements in the throughput, latency, and scalability of the platform when we raised the block size from 50 to 100 transactions per block while keeping a block timeout of 2 seconds. however, we have noticed a decrease in the throughput of the platform and an increase in latency when we steadily increased the block size to 150 transactions per block. it also implies that increasing the number of transactions in a block beyond 100 is unlikely to have a favorable effect on the platform's performance. 2in most cases, we have discovered that, whether there are a small number of clients and organizations or large number of clients and organizations, the ideal balance between throughput and latency was typically obtained with a block size of 100 transactions per block. both speed and latency consistently performed best with this block size. 3our tests have revealed that increasing the block timeout from 1 second to 2 seconds and up to 5 seconds result in a significant improvement in the throughput and average latency, under both moderate and full load conditions. however, increasing the block timeout from 2 seconds to 5 seconds can also have some drawbacks, especially for latencysensitive applications because longer validation and commit times for transactions can increase the overall transaction latency. additionally, setting the block timeout too high can increase the network resource utilization, as nodes must maintain transaction state for longer periods. finally, the extension of block timeout could potentially compromise the security of the platform. this is because longer timeouts provide more opportunities for intruders to attempt to capture the data. therefore, a careful planning and control are required when increasing the block timeout. acknowledgments this work is supported by the information and communications engineering department alkhawarizmi engineering college, university of baghdad. references [1] a. m. k. . al-ghraibawy, “the influence of organizational power on the achievement of entrepreneurship for business organizations an analytical study of the views of a sample of managers in the iraqi ministry of education”, jeas, vol. 28, no. 131, pp. 59– 82, mar. 2022. doi: https://doi.org/10.33095/jeas.v28i131.2234 [2] marian stoica and bogdan ghilicmicu (2020)," e-government in romania – a case study", journal of e-government studies and best practices, vol. 2020 (2020), article id 608643, http://dx.doi.org/10.5171/2020.608643 [3] a. s. elameer, "covid-19 and real egovernment and e-learning adoption in iraq," 2021 4th international iraqi conference on engineering technology and their applications (iiceta), najaf, iraq, 2021, pp. 323-329, http://dx.doi.org/10.1109/iiceta51758.202 1.9717570 [4] salman, r. h. ., shiltagh, n. a. ., & abdullah, m. z. . 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2023. https://doi.org/10.1016/j.ifacol.2022.10.122 http://dx.doi.org/10.1109/access.2020.3040443 http://dx.doi.org/10.1109/access.2020.3040443 https://www.hyperledger.org/ https://hyperledger-fabric.readthedocs.io/ (2023) 44-55، صفحة 2، العدد4دجلة الخوارزمي الهندسية المجلم كاظم إبراهيم أسامة 55 تقييم وتحليل اداء نظام حكومة الكترونية مؤمنة بطريقة البلوكشين الخاص  *حسين حمد* علي اسامة ابراهيم كاظم*  قسم هندسة المعلومات واالتصاالت/ كلية الهندسة الخوارزمي/ جامعة بغداد *،** gmail.com84ooosaamaa@البريد االلكتروني: * ahamad@kecbu.uobaghdad.edu.iq**البريد االلكتروني: الخالصة م الحكومة اإللكترونية، أفضت إلى العديد من المزايا، مثل لتفاعل مع المواطنين، والمعروفة أيًضا باساواستخدام التكنولوجيا لتقديم الخدمات العامة ان خاوف أمنية معينة، مثل التهديدات السيبرانية وانتهاكات في م استخدام الحكومة االلكترونية تحسين الكفاءة والوصول والشفافية. ومع ذلك، يتسبب أيًضا واحدة من التقنيات التي يمكنها المساعدة في التخفيف من تأثير الضعف األمني داخل الخاصة المؤمنة وغيرها. تعد تقنية البلوكشين ،البيانات وضبط الوصول ستة اضاف، من خالل تحليل سيناريوهين يتضمنان خاصةي منصة بلوكشين ، وه نظام الهايبرليدجر فابريكالحكومة اإللكترونية. تتناول هذه الدراسة أداء وقت انطالق و كتلة البلوكشينوحجم البيانات. تم تعديل عدة معامالت، مثل معدل إرسال تحت معدالت ارسال عالية كدراسات حالة مؤسسات حكومية ى إنتاجية النظام عل زيادة عددهالتحديد تأثير للمؤسساتإضافة تدريجية ايضا كما تم ين.هالسيناريوكال في خدمينالمستوعدد المؤسساتوعدد البلوكشين . بلوكشينمعاملة لكل المئة إلى حوالي البلوكشينند زيادة حجم وقابليته للتوسع. تم الحصول على نتائج مقبولة لألداء والتأخير ع وقت معالجة البيانات وتأخير ، لكن عندما تم إضافة المزيد من عظم الحاالتة في ما تمت مالحضة انه عند اضافة عدد من المؤسسات يصل الى ثالثة فقط فأن النتائج تكون مقبولايض الية كان له تأثير لمعدالت اإلرسال الع وقت البلوكشين، بدأت اإلنتاجية والتأخير تعاني من أداء ضعيف. كما أظهرت العديد من التجارب أن زيادة المؤسسات .جيد على اإلنتاجية والتأخير mailto:ooosaamaa84@gmail.com mailto:ahamad@kecbu.uobaghdad.edu.iq acknowledgments the format of the ijopcm, first submission this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 20, no. 1, march, (2024), p p. 8999 control system development of cap-seal assembling machine abdullah salih hamoud* salah al-zubaidi ** samaher mohammed sarhan*** mohd shukor salleh**** m. n. mohammed***** oday i. abdullah****** *department of control and systems/ maintenance authority/ midland refinery company/ daura refinery/ ministry of oil/bagdad/ iraq ** department of automated manufacturing engineering/ al-khwarizmi college of engineering/ university of baghdad/ iraq ***department of mechatronicss engineering/ al-khwarizmi college of engineering/ university of baghdad/ baghdad/ iraq ****department of manufacturing engineering/ faculty of industrial and manufacturing technology and engineering/ universiti teknikal malaysia melak/ melaka/ malaysia ***** department mechanical engineering / college of engineering/ gulf university/ sanad 26489/ bahrain ******system technologies and engineering design methodology/ hamburg university of technology/ 21079 hamburg/ germany *email: abdullahs.hamoud@gmail.com corresponding author ** email: salah.salman@kecbu.uobaghdad.edu.iq ***email: samaher.m@kecbu.uobaghdad.edu.iq ****email: shukor@utem.edu.my *****email: dr.mohammed.alshekhly@gulfuniversity.edu.bh ******email: oday.abdullah@tuhh.de (received 28 january 2023; accepted 11 october 2023; published 1 march 2024) https://doi.org/10.22153/kej.2024.10.004 abstract the cap-sealing assembling machine is vital in various packaging industrial sectors, particularly the oil sector. the conventional control system of such machines suffers from many demerits, e.g. low productivity, high production cost, high rejection rate, and requires frequent maintenance. therefore, the current research aims to develop a new control system (n.c.s) based on a programmable logic controller and human-machine interface system (plsc&hmi). hence, a fully automated cap-sealing assembling machine can be achieved. the machine is used to produce cap seals for engine oil containers. the performance of the new control system machine is evaluated and compared with the conventional control system (c.c.s) to examine the system feasibility and reliability. the aspects that are subjected to evaluation are the daily working hours (hrs.), glue consumption (kg), and rejection rate (%). the independent t-test is conducted to deliver a fair comparison and approve the effectiveness of the proposed control system. the obtained findings give the significant development of the proposed control system based on the dependent t-test result. the working hours are reduced to 31.15 hours, and maintenance durations are lowered to the minimum. also, the n.c.cs reduces the rejection by increasing the accuracy of the finished cap sealed from 88.3 to 99.42 % and consumed glues from 11.5 kg to 7.11 kg. keywords: plc, hmi, lubricants, control, packaging 1. introduction capping and sealing machines enable firms to protect the packaged products during handling, storing, and shipment until the machines are reached to the hands of the customers. automated systems are becoming more significant and interesting for the industrial sector and economics. aumailto:salah.salman@kecbu.uobaghdad.edu.iq https://doi.org/10.22153/kej.2024.10.004 abdullah salih hamoud al-khwarizmi engineering journal, vol. 20, no. 1, p.p. 8999(2024) 90 tomated systems produce potential merits, e.g. reducing product cost, waste, labor, improving production quality, reliability, and repeatability. hence, the automation of different machines can achieve the mentioned goals. sealing machines are widely utilized in manufacturing and have typical applications, e.g. sealing and packaging. in the 80’s, hand sealing was performed using gloves to press the heated foils on the containers. this is not a reliable operation and has many demerits. thus, such machine automation has started occupying the sealing industry for many products. recently, more companies have begun changing their manual assembling to automated mode using industrial robots and automation [1]. the automated capping and sealing equipments provide unlimited merits for the industrial packaging sector. the automated equipment strongly enhance productivity by reducing workers' number, directing the workers to only manually-concentrated tasks, and protecting the workers from toxic and unsafe operating conditions. further, automated equipment lower production costs, sustain qualified packaged products, maintain hygienic circumstances, and avoid direct hand contact to eliminate probable product contamination. the control strategy of the different packaging machines have to fulfill some needs, including speed tuning, coordinating between the detected and executed parts, controlling the driving units, enabling a smooth, active sequence of tasks, and ensuring a secure and safe operating mode to protect the operators [2]. numerous studies have been conducted in developing industrial automation control systems to resolve the troubleshooting associated with manual and semi-automatic machines. for instance, adizue u. l et al designed and fabricated a small-scale automated can foil sealing machine. the machine was tested later and obtained an efficiency of 78% [3]. mingyu gao et al. developed an automatic assembling system for the sealing of rings by using machine vision [4]. experimental findings showed that the developed system could grab and place the sealing rings on the sealing port speedily and successfully. d.kanimozhi et al [5] designed and fabricated a mini and simple packaging machine using plc software to control and automate the packaging process. the productivity was increased, and production time decreased by using this system. su.hema et al. [6] developed and implemented a successful automatic filling and sealing machine. several features were added for different stages of the work, such as defined volume specification. plc was adopted to control various operations and the monitoring process was done by using scada system. md abu sayeed and md. rafiquzzaman [7] developed an automated system for pe bags. the developed system supplied plastic bag using vacuum grippers and accomplished the sealing process automatically. the polyethylene bag was hanged with dead weight to evaluate the sealing strength. anca and carman [8] proposed a plc control system for injection molding to increase the yield rate of flowerpot products. in addition to the imo ismart edrd-20 plc, the system involves a 24 v dc power supply, dc motors, temperature sensors, input and output leds, buttons, and switches. the plc was programmed by the ladder language and validated with simulator software. the proposed system was successfully implemented. abueejela et al. [9] presented a plc control system for a small-scale packaging machine. small cubic woods with 2.8 cm3 each were packaged into an 18 cm3 paper box. the mitsubishi fx2n 32mt plc was fed with data through inductive and photoelectric sensors. the plc was programmed by ladder language. dc motors drive the output actuators to move cubic wood on the conveyor belt, which receives a signal from the control system. the presented system showed good performance by packaging twenty-one boxes every minute. a plc control system for a traditional vertical injection machine was proposed by cui et al. [10]. the achieved results revealed that the performance of the automated machine was characterized by fast, efficient, reliable, and stable performance compared with the old control system that entirely relied on the relay control strategy. manhas et al. [11] automated the motion of the conveyor belt by using a plc control system to improve the productivity of the bottle-filling production line. also, the filling level was automatically controlled within a particular time in seconds to ensure that all bottles were filled with the required amount. a mitsubishi plc was programmed by ladder language and simulated by gx work 3 software. the achieved findings agreed with the specified parameters in the ld program. luo [8] designed a plc control system for packaging machine. the performance of the designed plc system, according to the author, has improved the production capacity, operating stability, and provided intuitive and convenient working platform. the cited work in majority adopted plc system to control the traditional machine and to improve their performance in terms of some indexes. the current study motivation is to develop and implement a plc-hmi control system for cap seal assembling machine to solve the issues correlated to alaa kareem mohamme al-khwarizmi engineering journal, vol. 20, no. 1, p.p. 116(2024) 91 real industrial problems. the challenge for implementing the developed control system comes from the fact that this machine works within a set of other machines in a production line. the machine incorporates sub-operation that must be precisely controlled and coordinated to confirm a smooth production cycle with high productivity, good quality, and fewer maintenance periods. 2. development of new control system (n.c.s) for cap seal machine the current cap seal assembling machine works within a set of other machines that form an integrated production line of engine oil assembled in al-dorah oil refinery. this production line involves injection molding machines for caps and plastic containers, cap seal assembling machines, and packaging machines. any stoppage in any of those machines stops production and cause extra losses consequently affect the monthly production plan and cause a failure to satisfy market demand. these losses are considered warranted due to conventional control systems incorporated in these machines. the machines mostly include independent electronic circuits that rely mainly on relays and timers. the cap seal assembling machine is selected among other machines to develop the control system. developing the control systems is crucial due to the many sequential tasks that the machine delivers. the process flow of this machine begins with feeding the hopper with unglued caps. the caps are directed by the sorter orienteer to the conveyer belt to be identified by the cap detector to prepare them for gluing. the hot melted glue is deposited on the interior surface of the caps by the seal gun. the seal gun consists of a nozzle that injects a certain amount of glue controlled by a solenoid valve. an aluminum foil ribbon winded on a roller is cut into circular strips to be placed on the glued caps and pressed by the piston. the caps are passed onto all these sub-operations by a star wheel driven by a motor and camshaft. figure 1 depicts the four suboperations while the entire machine, including the hopper, feed sorter, hot melted glue, old hmi, and finished sealed caps, are illustrated in figure 2. fig. 1. four sub-operations of cap seal machine. abdullah salih hamoud al-khwarizmi engineering journal, vol. 20, no. 1, p.p. 8999(2024) 92 fig. 2. entire cap sealing machine. this machine has many problems: 1. low production rate 2. delay in response time. 3. high rejection rate 4. high consumption of glue and seals 5. needs frequent maintenance. 6. lack of harmony and coordination between sub-operations due to independent conventional electronic circuits for each one. 7. lack of safety emergency stop. the frequent maintenance of this machine is due to several issues of the conventional control system that depend entirely on the relays and timers. and among those issues, there are the frequent delays caused by extra or less amount of eccentric injected glue and under or over-phase placing of the star wheel. the right machine phase means the four caps must be placed under the right locations: cap detector, glue gun, seal cutter, and pressing piston, as depicted in figure 1. other caps are located between the four active caps. the electrical and mechanical issues occur due to the delay in the relay signal to the cutter and press piston and mechanical loose in the movement of the camshaft, respectively. consequently, they expose the star wheel to be in the wrong phase and subject it to frequent damage if the cutter and piston move down on the star wheel teeth instead of foil seal. these issues cause many stoppages for machine maintenance that may be done weekly or every few days. furthermore, adding a new function for protection or accuracy to the conventional control system increases the wiring system's complexity and obstacles, considering that these functions should be performed in milliseconds. figure 3 shows the flow chart of the conventional machine. alaa kareem mohamme al-khwarizmi engineering journal, vol. 20, no. 1, p.p. 116(2024) 93 fig. 3. flow chart of the conventional control system of cap seal machine. a programmable logic control-human machine interface (plc-hmi) system was developed and implemented to increase productivity, minimize production time, improve product quality, provide safety, lower maintenance, and reduce waste/ scrap materials. a plc is generally classified as a microprocessor-based application. the program of machine control is written in ladder. the ladder program consists of three stages; the plc control system does a particular task in each stage. omeron plc is selected in this study to perform the following stages as described below: 1. ready for start stage: this is the first stage, in which plc checks the machine operating conditions including all the statuses of machine alignment, drive-motor protection, safety door, cap in loader, instrument air, cap counter, and hot-melt system. if all these statuses are ok, the machine is considered ready to start; otherwise, the alarm appears on the hmi. 2. startup stage: in this stage the operator presses the start push button once he receives the signal of ready to start. the plc sends signal to the driver motor to start the machine. there are four dc driving motor: the first one drives the conveyor belt between the hopper and sorter to provide continuous feeding of unglued caps; the second motor drives the sorter, which maintains all the caps are placed on the on their outer surfaces; the third motor drives the second conveyer belt between sorter and star wheel; finally, the star wheel rotates by the motor and camshaft to distribute cups on the right phase in which one cap is located to correct the 3. running stage of cap seal assembling machine: in this stage, the plc receives the signal that ensures the caps exist on the conveyor belt. at the same time, the plc checks the positive and negative edge signals of the machine phase sensors. once the plc receives the positive signal, the plc delivers an order to the cutter and piston to move upward and start gluing the cap with the hot melted glue by the glue gun, cut the al-foil seal by moving down the cutter, and press down the seal on the glued gun by the piston. otherwise, a negative edge start turn on all driving motors and hot melt gluing system is the machine in the right phase? start gluing the cap and stop when the elapsed time preset by the timer is reached start cutting of al-seal foil by moving down the cutter and once the cutting done, move up the cutter start pressing the seal on the glued cap by moving down the piston and once the pressing done move the piston does the operator want to stop machine? end yes yes no no abdullah salih hamoud al-khwarizmi engineering journal, vol. 20, no. 1, p.p. 8999(2024) 94 signal is delivered to the plc in case both the cutter and pressing piston are in the down positions. the hot melt system stops the glue injection by signal from the plc when the injection time is elapsed. also, when the cutter and pressing piston actions are done, the plc delivers a signal to the cutter and piston to move upward and stop cutting and pressing. the operator uses the hmi to set both numbers of caps that must be sealed and elapsed time for injecting glue. when the plc receives a signal that a new cap seal is produced, the counter starts to count and compare the number of the made cap seal with the pre-set number selected on the hmi by the operator, as illustrated in figure 4. if the number of glued and sealed caps is reached, the machine automatically stops; otherwise, the production cycle continues until it reaches the preset number of final products. fig. 4. flow chart of the new control system (n.c.s) for the cap seal machine. 3. results and discussion the preceding section has described the developed plc-hmi system integrated with the cap seal machine. in this section, the performance of the new control system was evaluated based on some key aspects compared with conventional control machine. the working hours (including maintenance time), rejection rate (%), and amount of the consumed glue in kg (include the wasted glues). the production plan for each machine is to produce 40,000 cap seals in 20 working days. the daily working hours, rejection rate, and consumed glue were recorded as shown in table 1. three parameters were considered in this study, as illustrated in the above table. the bottom of table 1 shows the sum, average, maximum, minimum, and standard deviation of each parameter for both machines. it is clear from the table that the reductions in working hours and consumed glue were 61.22 hours and 3.39 kg, respectively. the noticeable decrease in the working hours was due to the elimination of maintenance time included in the working hours. the maintenance time for the c.c.s machine was necessary to clean the glue system's components, which is the reason for the increasing working hours. on the other hand, the maintenance time was reduced to minimum levels (annually) for the n.c.s machine due to the insertion of the developed plc alaa kareem mohamme al-khwarizmi engineering journal, vol. 20, no. 1, p.p. 116(2024) 95 hmi system. that means the machine can be able to continue in production without stopping during the working hours. the rejection rate is an important aspect that plays a crucial role as a key performance index of the evaluation. the reduction in the average rejection rate was 11.125%. in other words, the rejection rate was reduced down to 0.575%. the high amount of the consumed glue is consistent with the high rejection rate of the c.c.s machine. the standard deviation values of the three parameters for the n.c.s machine were much less than the corresponding ones of the c.c.s machine. this reveals that the fluctuation of the collected data around the mean values is less after modification. in contrast, there was high deviation of the observations around the mean for the c.c.s machine. also, the maximum and minimum values of the three parameters ensure this behavior. this reflects the stability of the n.c.s machine and its effectiveness compared with the c.c.s one. figure 5 shows the control system of the cap seal machine with the plc-hmi system. figure 6 shows the cap seal product produced by c.c.s and n.c.s machines. there is evident a difference in the quality of the cap seal before and after modification of the machine in terms of the texture of the cap / seal and the amount of injected glue and its distribution. to examine the reliability of the developed plc-him system, it is better to conduct the dependent t-test using spss. the experimental data in table 1 is subjected to this test to check the validity of the modification made by the developed system on the machine's efficiency. the null hypothesis supposes that the average output of each parameter is the same before and after development. spss was fed with collected data to run the dependent t-test, and the achieved results were tabulated as shown in tables 1, 2, and 3, respectively. table 2 shows the paired samples statistics and provides the descriptive statistics (i.e., means, number of data sets, standard deviations, and standard errors of means) for both control systems. table 3 is paired sample correlations and shows the degree of the correlation between the parameters and the level of significance of the two-tailed test to evaluate the hypothesis of zero correlation. table 3 is the paired samples test and shows the results of the t-test analysis. the statistical values given under the label paired differences are determined by subtracting c.c.s parameter value from the n.c.s one. the three measures (mean, standard deviation, and standard error of mean) of these differences are provided here with a confidence level of 95% of the mean of differences. the last three columns are the t-test results. the results of this test give the t-statistic values of 11.133, 6.362, and 29.711, respectively. the degrees of freedom are 19 degrees. the p-value of the twotailed for the three pairs is 0.000, which is much less than the traditional 5% or 1% significance level. hence, in this case, the null hypothesis can be rejected at a 5% (or 1%) level of significance. that means that the performance of the n.c.s machine with embedded plc-hmi system has indeed improved and enhanced with a high degree of significance compared with c.c.s machine. therefore, the developed system has proposed solutions to the existing problems and improved & enhanced the performance of the cap-sealed machine by reducing the rates of all three aspects that were considered in the current study. fig. 5. new control system (n.c.s) of cap seal assembling machine abdullah salih hamoud al-khwarizmi engineering journal, vol. 20, no. 1, p.p. 8999(2024) 96 table 1, experimental data of conventional and new control systems (c.c.s & n.c.s) for the cap seal assembling machine table 2, paired samples statistics table 3, paired samples correlations pairs n correlation sig. pair 1 working hoursc.c.s & working hoursn.c.s 20 .011 .965 pair 2 consumed gluec.c.s & consumed gluen.c.s 20 -.349 .131 pair 3 rejection ratec.c.s & rejection raten.c.s 20 .134 .573 no. convention control system (c.c.s) new control system (n.c.s) working hours consumed glue (kg) rejection rate (%) working hours consumed glue (kg) rejection rate (%) 1 4 0.6 10 1.5 0.35 0.6 2 3.67 0.4 10 1.5 0.35 0.5 3 4.5 0.65 12 1.4 0.34 0.5 4 5 0.72 13 1.5 0.35 0.5 5 6 0.75 14 1.5 0.35 0.6 6 4.1 0.55 11 1.7 0.38 1 7 3.7 0.4 10 1.5 0.36 0.5 8 3.8 0.46 10 1.4 0.35 0.3 9 4 0.59 12 1.6 0.36 0.6 10 4.5 0.63 12 1.5 0.35 0.5 11 7 0.77 15 1.6 0.35 0.7 12 3.8 0.41 10 1.9 0.39 1 13 3.9 0.42 11 1.5 0.35 0.4 14 4 0.62 10 1.5 0.34 0.4 15 6 0.73 13 1.6 0.35 0.5 16 5 0.71 13 1.5 0.35 0.5 17 8 0.85 15 1.6 0.36 0.7 18 3.7 0.4 10 1.5 0.35 0.5 19 4.2 0.44 12 1.65 0.36 0.6 20 3.5 0.4 11 1.7 0.37 0.6 sum 92.37 11.5 234 31.15 7.11 11.5 average 4.6185 0.575 11.7 1.5575 0.3555 0.575 max 8 0.85 15 1.9 0.39 1 min 3.5 0.4 10 1.4 0.34 0.3 stdev. 1.225348 0.149543 1.688974 0.116161 0.012344 0.174341 pairs mean n std. deviation std. error mean pair 1 working hours-c.c.s 4.6185 20 1.225348 .273996 working hours-n.c.s 1.5575 20 .116161 .025974 pair 2 consumed gluec.c.s .5750 20 .149543 .033439 consumed gluen.c.s .3555 20 .012344 .002760 pair 3 rejection ratec.c.s 11.7000 20 1.688974 .377666 rejection raten.c.s .5750 20 .174341 .038984 alaa kareem mohamme al-khwarizmi engineering journal, vol. 20, no. 1, p.p. 116(2024) 97 table 4, paired samples test (a) (b) (c) fig. 6. glued and glued-sealed caps: (a) glued cap by c.c.s machine (b) glued caps by n.c.s machine (c) cap sealed by the developed machine 4. conclusions the current study has proposed a new control system based on plc-hmi integrated with the cap seal machine. the performance of the developed system has been tested and evaluated by the dependent t-test to claim and ensure the effectiveness and feasibility of its development. it has approved its efficacy and reliability in solving the problems that were associated with the c.c.s machine and improved its performance and functionality through: 1. reduction of the working hours down to 31.15 hrs. 2. minimization of the cleanup time to a minimum level. 3. increasing the accuracy from 88.3% to 99,423% by reducing the rejection rate. 4. the performance of the glue feeding system is highly improved by lowering the glue consumption from 11.5 to 7.11 kg per 40 000 cap seals. acknowledgment the authors would like to thank the department of instrumentation and control, midland refinery company, ministry of oil, iraq, for the financial support of this research. pairs paired differences t df sig. (2-tailed) mean std. deviation std. error mean 95% confidence interval of the difference lower upper pair 1 working hoursc.c.s & working hoursn.c.s 3.061000 1.229612 .274950 2.485524 3.636476 11.133 19 .000 pair 2 consumed gluec.c.s & consumed gluen.c.s .219500 .154289 .034500 .147291 .291709 6.362 19 .000 pair 3 rejection ratec.c.s & rejection raten.c.s 11.125000 1.674538 .374438 10.341292 11.908708 29.711 19 .000 abdullah salih hamoud al-khwarizmi engineering journal, vol. 20, no. 1, p.p. 8999(2024) 98 references [1] m. r. pedersen, l. nalpantidis, r. s. andersen et al., “robot skills for manufacturing: from concept to industrial deployment,” robotics and computerintegrated manufacturing, vol. 37, pp. 282– 291, 2016. [2] qiao, g., discussion on the control technology in the design of packaging machinery, international conference on advances in social sciences and sustainable development (asssd 2018). [3] adizue u. l, agbadah s. e, ibeagha d. c, falade y. o,” design and construction of an automated adjustable-can foil sealing machine”, international journal of engineering and applied sciences, volume-4, issue-9, september 2017. [4] mingyu gao, xiao li, zhiwei he, and yuxiang yang,” an automatic assembling system for sealing rings based on machine vision”, journal of sensors, vol 2017, article id 4207432, 12 pages [5] kanimozhi d, devi b n and manochandar t 2015 plc controlled automatic food packaging machine int. j. eng. trends technol. 30(1) 33–36. [6] su.hema, s.sonali, m.rajendiran, " automatic yeast filling and sealing machine using plc", international research journal of engineering and technology, volume: 05 issue: 03 | mar-2018. [7] avik das, abu sayeed, & md. rafiquzzaman. (2019). development of an automated sealing system for polythene bag. journal of automation and automobile engineering, 4(1), 25–32. http://doi.org/10.5281/zenodo.2611069. [8] anca apătean, c.m., using a plc to command a plastic injection molding machine. acta technica napocensis, 2015. 56(3): p. 1-6. [9] abueejela, y., et al., automated packaging machine using plc. international journal of innovative science, engineering & technology ijiset, 2015. 2: p. 282-288. [10] cui, y. and j. chen, design of control system for vertical injection moulding machine based on plc. iop conference series: materials science and engineering, 2018. 439: p. 032093. [11] manhas, k., et al., design and implementation of bottle filling automation system for food processing industries using plc. 2019. 04: p. 01-09. [12] luo, d., design and implementation of automatic packing machine system based on plc. frontiers in computing and intelligent systems, 2022. 2: p. 129-131. http://doi.org/10.5281/zenodo.2611069 http://doi.org/10.5281/zenodo.2611069 (2024) 89-99، صفحة 1، العدد20المجلد جلة الخوارزمي الهندسيةم عبد هللا صالح 99 وختم االغطيةتجميع تطوير نظام تحكم لماكنة **** محمد شكور صالح *** سماهر محمد سرحان ** صالح الزبيدي * عبد هللا صالح حمود ******عدي إبراهيم عبد هللا ***** محمد الشيخلي وزارة النفط/بغداد/العراق الدوره/ مصفى شركة مصافي الوسط/ هيأة الصيانة/-قسم السيطرة والنظم * . العراق /جامعة بغداد /كلية الهندسة الخوارزمي /قسم هندسة التصنيع المؤتمت ** العراق /بغداد /جامعة بغداد /كلية الهندسة الخوارزمي /قسم هندسة الميكاترونكس *** لدوريان تونجا 76100 /هانج تواه جاي /ملقاالجامعة الماليزية التكنولوجية /والهندسة كلية تكنولوجيا الصناعة والتصنيع /قسم هندسة التصنيع**** ماليزيا /ملقا البحرين /26489سند /الخليججامعة /كلية الهندسة /قسم الهندسة الميكانيكية ***** ****** تقنيات النظام ومنهجية التصميم الهندسي/ جامعة هامبورغ للتكنولوجي/ 21079 هامبورغ/ ألمانيا abdullahs.hamoud@gmail.com: البريد االلكتروني* salah.salman@kecbu.uobaghdad.edu.iq:البريد االلكتروني** samaher.m@kecbu.uobaghdad.edu.iq:البريد االلكتروني *** shukor@utem.edu.my: البريد االلكتروني**** dr.mohammed.alshekhly@gulfuniversity.edu.bh:البريد االلكتروني***** oday.abdullah@tuhh.de:البريد االلكتروني ****** الخالصة في مختلف قطاعات صناعة التعبئة والتغليف، وخاصة قطاع النفط. النوع التقليدي ذو نظام التحكم القديم المكائن المهمةمن عتبر آلة تجميع وختم الغطاء ت ك، يهدف البحث لهذه اآلالت يعاني من العديد من العيوب مثل انخفاض اإلنتاجية، ارتفاع تكلفة اإلنتاج، ارتفاع معدل الرفض، ويتطلب صييييييييانة متكررة. لذل تجميع للحصيييييول على ماكنة ( plc&hmiإلى تطوير نظام تحكم جديد يعتمد على وحدة تحكم منطقية قابلة للبرمجة ونظام واجهة اإلنسيييييان واآللة الحالي وموثوقيت . القديم لفحص جدواه النظامعلب زيت المحرك. تم تقييم أداء نظام السييييييييطرة الجديد ومقارنت بفي يتم اسيييييييتخدامها لمؤتمتة بالكامل الغطاءوختم الغير مستقل للحصول على مقارنة tم(، ونسبة الرفض ٪(. تم إجراء اختبار غكبال، استهالك الغراء للتقييم هي ساعات العمل اليومية الجوانب التي خضعت نظام السيييطرة المقترش بناءع على نتيجة اختبار عادلة باإلضييافة إلى التأكد من فعالية نظام السيييطرة المقترش. أشييارت النتائج التي تم الحصييول عليها إلى فعالية t سيييييياعة، كما تم تخفيض فترات الصيييييييانة إلى الحد ا دنى. كما تم تقليل معدل الرفض من خالل رفع دقة انتاج 31.15. حيث تم تخفيض سيييييياعات العمل إلى كجم.7.11كجم إلى 11.5%، كما تم تقليل كمية الغراء المستهلك من 99.42إلى 88.3 الغطاء النهائي المحكم الغلق من mailto:salah.salman@kecbu.uobaghdad.edu.iq mailto:samaher.m@kecbu.uobaghdad.edu.iq mailto:samaher.m@kecbu.uobaghdad.edu.iq mailto:oday.abdullah@tuhh.de mailto:oday.abdullah@tuhh.de this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 21, no. 1, march (2025), pp. 89-99 mm for 5g wireless communication system using path loss models communication channelave w dawood o. zinah , khwarizmi engineering college-al ,engineering communication andormation nfof i epartmentd iraqbaghdad, baghdad,university of zina_osama@kecbu.uobaghdad.edu.iqemail: (received 24 december 2023; revised 23 april 2024; accepted 5 june 2024; published 1 march 2025) https://doi.org/10.22153/kej.2025.06.001 abstract multiple-input multiple-output (mimo) antenna topologies in wireless communication systems can increase channel capacity and dependability. the use of millimeter (mm)-wave frequency bands in conjunction with other technologies is a substantial step in achieving high data rates for sophisticated ai and multimedia devices. however, transmitting mm wave frequency signals presents challenges such as fading, time delay, propagation and scattering loss. therefore, optimising propagation parameters is critical to improving performance. this paper examines the influence models for path loss (pl): abg and ci on the design and analysis of a 4×4 mimo w-ofdm system employing 16-qam modulation technique for 5g wireless communication. this paper examines the system using the ci and abg pl models to assess pl in db, normal distribution and standard deviation. this paper uses 16-qam digital modulation, and the simulation results show that the ci pl model-based mimo w-ofdm system is very robust and successful in signal recovery. keywords: mimo; millimeter wave; path loss; abg model; two-parameter ci model 1. introduction the increasing need for wide availability of data and improved mobile data speeds has led to a decrease in the available spectrum within the conventional frequency bands utilised for wireless communication, that is, a frequency lower than 6 ghz. fifth-generation (5g) wireless communications are being developed as a result of technological innovations such as multiple-input multiple-output (mimo) [1],[2] and new millimeter-wave (mm wave) frequency band spectrum allocations [3]. these techniques are useful for dealing with the current spectrum shortage [4]. to ensure the accurate, dependable construction of 5g systems, possessing a comprehensive comprehension about the parameters of the propagation channel encompassing microwave and mm wave frequencies is necessary. revolutionary technologies are predicted to be used by developing 5g communication systems [5]. developing dependable channel models is important to support engineers in the design because of new possible spectra and innovative architectural concepts [6-8]. various researchers have already analysed channel characterisation in the mm wave and centimeter (cm)-wave bands [9], [10]. performed modelling and measurements of outdoor propagation in the 60ghz frequency band in different city streets [11 14]. in recent years, several efforts focused on the examination of mm wave channels, including measurement campaigns, prototype implementations and modelling advancements. according to information theory, three main solutions may be used to enhance system capacity remarkably and meet the design objectives of 5g. ultradense networks refer to a network architecture characterised by a much higher density of base stations (bs). the use of small-cell technology, commonly referred to as network densification, has already been included into 4g wireless cellular mailto:zina_osama@kecbu.uobaghdad.edu.iq https://doi.org/10.22153/kej.2025.06.001 zinah.o.dawood al-khwarizmi engineering journal, vol. 21, no.1, pp. 7088 (2025) 90 networks. increasing the density of a network can enhance its capacity [15-17]. large amounts of additional bandwidth will be made available to support higher throughput transmission as a result of the migration to higher frequencies [18]. a particularly promising candidate could be mm wave; carrier frequencies range from 30 ghz to 300 ghz. a high spectrum efficiency can be achieved: by completely making use of the space resources, massive mimo is a technology that utilises a high number of antennas on the transmitter and receiver to increase the accuracy of wireless communication systems. mimo technology can substantially enhance spectrum efficiency through the use of a considerable quantity of antennas that often number 100 or more. [19]. each of these technologies will increase the throughput of wireless networks by an order of magnitude or more compared with the current generation of 4g systems. each of these three solutions exhibit a symbiotic convergence in several aspects: reduced cell sizes are advantageous in the context of mm wave communications at short distances, whilst the substantial antenna gains facilitated by massive mimo systems are beneficial in mitigating the substantial signal attenuation experienced by mm wave transmissions. the short wavelength of mm wave frequencies makes them appealing for massive mimo because the actual dimension of the antenna array may be greatly decreased. if a method to use each of these technologies exists, the 1000fold increase in 5g capacity can be achieved. the existing mm wave technology raises the operating frequency toa the mm wave band whilst utilising the fundamental design principles of mimo technology. this paper contributes to the enhancement of the core design concepts of mimo technology and the use of the mm wave band for operation. the integration of mm wave frequencies partly mitigates the substantial signal attenuation associated with these frequencies and hence enables the establishment of practical minute cell sizes within coverage spans spanning 100 m. this approach not only brings the system closer to achieving a substantial increase in the mimo gain but also mitigates the substantial signal attenuation seen at mm wave frequencies and hence facilitates the implementation of feasible small cell sizes [14]. 1.1.channel models underlying (single_input, single_output, siso, mimo) wireless channels are classified as largeand small-scale propagation effects (largeand smallscale fading, respectively). path loss (pl) and shadowing effects caused by great distances are the major causes of large-scale fading. by contrast, short-range fluctuations such as positive and negative interferences from various pathways cause small-scale fading. 1.2. mimo system mimo technology may improve system capacity without increasing bandwidth or broadcast power by increasing the number of transmitting and receiving antennas. the transmitter antenna n and the reception antenna m can gather the signal given by the [1]. y=hx+n, …(1) where y is the received signal, and h is a matrix is used to deal with transmitted signal x and noise n over the whole channel. assuming equal rayleigh channel matrices and average power allocation, the mimo system’s capacity may be expressed in the equation for capacity given by [15]. 𝐶 = ∑𝑖=1 𝑀  𝐵𝑖log2⁡(det⁡[𝑰𝑁 + 𝑃𝑡𝑖 𝑀𝜎𝑛 2𝑯𝑯 𝐻]) = ∑𝑖=1 𝑀  𝐵𝑖log2⁡(det⁡[𝑰𝑁 + 𝜌 𝑀 𝑯𝑯𝐻]), … (2) where the sent signal x, where bi, det, in. the first parameter to be determined is the bandwidth allocated to each user. next, the determinant of the given matrix needs to be calculated. in conclusion, determining the identity of the matrix represented by m and n is necessary. in addition, the average signal-to-noise ratio (snr) is shown for each channel. when referring to the conjugate transpose of a matrix h, the abbreviation ‘hh’ is often used as a symbol. the channel matrix can be subdivided into smaller components. the equation of the matrix used to deal with transmitted signal is given by [15]. 𝑯 = [⁡ ℎ1,1 ℎ1,2 … ℎ1,𝑁 ℎ2,1 ℎ2,2 … ℎ2,𝑁 … … ⋱ … ℎ𝑀,1 ℎ𝑀,2 … ℎ𝑀,𝑁 ]⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡…⁡⁡(3) as previously shown, each individual component of the rayleigh channel matrix may be interpreted as follows by [16]: hi,j = α + jβ = √α2 + β 2ejarctan β α = |hi,j|e jϕi,j …(4) where α,β is a rayleigh distributed random variable, and |h (i,j) |are random distributed variables. the expression of h (i,j) may be expressed below. the rayleigh channels are the independent and identically distributed complex zero mean and unit entries; the equation for the capacity is given by [16]. zinah.o.dawood al-khwarizmi engineering journal, vol. 21, no.1, pp. 7088 (2025) 91 hi,j = normal (0, 1 √2 ) + jnormal (0, 1 √2 )⁡⁡⁡⁡⁡… (5) where the normal distribution is generated by normal. as a result, h (i,j) conforms to the 𝑥2 2 distribution using two degrees of freedom that e= [ℎ𝑖,𝑗] = 1. because the eigenvalue of 𝐼𝑁 + 𝑝 𝑚 𝐻𝐻𝐻⁡is produced by the determination equation, the capacity can be calculated by primarily using the eigenvalue of 𝐻𝐻𝐻 considering the eigenvalues of the two matrices : {𝐴𝑝 × 𝑞, 𝐵𝑞 × 𝑝, 𝑝 ≤ 𝑞} eigenvalue of are 𝐴𝐵𝑃×𝑃⁡ and𝐵𝐴𝑞×𝑞 equal. because a zero eigenvalue does not contribute to the capacity effect, the eigenvalues of hhh and hhh are the same, and λ = λ1,⁡𝜆2,……….⁡⁡, 𝜆min⁡(𝑁,𝑀) provides the nonzero eigenvalues of the b. the equation for the capacity is given by [16]. b = { hhii, m < n, hhh,m > n. ⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡… (6) the mimo capacity in this case may be expressed as follows: ⁡𝐶 = ∑  m i=1 bi log2 (det [𝐈n + ρ m 𝐇𝐇h]) =⁡⁡∑  m i=1 bi log2 (∏  min(n,m) i=1   [1 + ρ m λi 2]) … (7) mimo capacity analysis frequently employs singular value decomposition (svd). the channel matrix in svd is broken down by the following: 𝐻 = 𝑈𝐷𝑉𝐻 ⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡…(8) when d is a matrix with the dimensions m by n, u and v are unitary matrices with the dimensions m by m and n by n, respectively, whose nonzero norm by the diagonal components is equal to the singular values of h. thus, equation (1) may be expressed as follows: ⁡𝑌 = 𝑈𝐷𝑉𝐻𝑥 + 𝑁⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡ …⁡(9) 1.3.from mimo to mm mimo massive mimo, in combination with other technologies such as as small cells, (hetnets) and (mm wave) technology, is positioned to play a remarkable role in the development of 5g networks, which are now working to deal with the issues given by the transmission rate bubble. the previously mentioned options are seen as prospective solutions to enhance this existing pattern further. considerable mimo research has shown that just increasing the number of transmitter antennas enables constantly obtaining a greater snr whilst maintaining perfect channel state information and completely removing pilot contamination. cellular densification is an additional effect of massive mimo. similar to cooper’s law, the increase in capacity will mostly result from the deployment of more dense cells. the expanding challenges faced by massive mimo technology include concerns related to energy efficiency and the provision of low latency backhauls, which are crucial for facilitating higher transmission rates, amongst several other factors [19-21]. 1.4. free space propagation model the assumption that underpins the model of propagation in free space is that the surrounding environment is clear of any interference or impediments. thus, elements such as reflection, refraction and other effects of a similar kind are not accounted for in this model. whilst communication occurs between entities, the use of the omnidirectional antenna wave transmission model may be employed to account for power attenuation between the transmitter and receiver. this outcome can be accomplished by using the relevant equation given by [7]. pr pt = [ √g 4πd ⁡λ] ⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡…⁡(10) in the context of free space transmission, the variables pr, pt, g, λ and d represent the received power, transmitted power, product of the transmitter and receiver antenna field radiation patterns, wavelength, and distance between the transmitter and receiver, respectively [11]. free-space path loss (fspl) refers to the reduction in signal strength or attenuation of radio energy between the feed points of two antennas. fspl is computed using equation (10); the equation of fspl is given by [5]. fspl = 20log 10 (d) + 20log 10 ( 4π c )⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡…⁡⁡(11) where the operational frequency starts at f = 28 ghz, and the distance between the transmitter and receiver is d = (100–300 m). the two pl models for better comparability are also considered. the close in free space (ci fs) reference distance pl model is first considered. equation (1) provides the expression for the ci fspl model. the equation of plci is given by [5]. (f, d)[db] = plfs(f, d0)[db] + 10⁡n⁡log 10 ( d d0 )⁡⁡⁡⁡ …(12) where n is the pl exponent, and (f, d0) is the fs pl for an isotropic antenna at a distance of = 1 m [17]. thus, equation (13) can be derived by [5], as follows: ⁡⁡plci(f, d)[db] = plfs(f, 1)[db] + 10⁡n⁡log10(d)⁡⁡ zinah.o.dawood al-khwarizmi engineering journal, vol. 21, no.1, pp. 7088 (2025) 92 ⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡… (13) the loss of fs propagation at a distance = 1 m equation now becomes, given by [5]. ⁡plfs(f, 1m)[db] = 20log10 ( 4πf c )⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡…⁡⁡(14) where c denotes light’s speed. the final equation of the ci model, which is given by equations (13) and (14) as follows by [5] ⁡plci(f,d)[db]=⁡20log10 ( 4πf c )10⁡n⁡log10 ( d d0 ) ⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡…⁡(15) the equation of pl ci model can be represented by [11]: ⁡⁡plci(f, d) [db]⁡= fspl(f, d0)[db] +10n log10 ( d d0 ) + χ σ ci, where d ≥ d0⁡⁡ ⁡ ⁡ …(16) where n is the path loss exponent (ple), χci is the ci fs reference distance, and f is also expressed in gigahertz (for the ci). with a standard deviation measured in db, σ represents a zero-mean gaussian random variable. to determine the mean pl with distance and frequency, the ci model employs two parameters (the ple n and χσ ci), whereas the abg model requires three parameters. a helpful feature of equation (16) is that starting at d0, 10n expresses route loss in db as a function of decades of distances, which makes mentally computing power over distance when d0 is set to 1 m extremely simple [11]. in (16), the carrier frequency is represented by the symbol f, and the fspl at a t-r distance to separation of d0 in db is indicated by the symbol fspl (f, d0); the equation is given by [11]. fspl(f, d0)[db] = 20 log 10 ( 4πfd0 × 109 c )⁡⁡⁡⁡⁡…⁡(17) the ci model may be expressed as follows by [11]: plci(f, d)[db] =fspl(f, d0)[db]+ 10nlog10⁡(d/d0) + χ σ ci =10nlog10⁡( d d0 ) + 20log10⁡( 4πd0 × 109 c ) ⁡+20log10⁡(f) + χ σ ci =10nlog10⁡( d d0 ) + η + 20log10⁡(f) + χ σ ci, where d ≥ d0 , η = 20log10 ( 4πd0 × 109 c )⁡⁡⁡⁡⁡⁡⁡ ⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡… (18) χ σ ci⁡= plci(f, d)[db]− fspl⁡(f, 1 m)[db] − 10nlog10⁡(d) ⁡= a− nd⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡ … (19) where a represents the difference between plci (f, d)[db] and fspl(f, 1m)[db], whereas d represents 10 log10(d). then, the sf standard deviation is σci = √ ∑ ⁡ χ σ cl⁡2 n = √ ∑ ⁡ (a − nd)2 n ⁡⁡⁡⁡⁡ ⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡… (20) where n stands for the number of pl data points. this paper shows that for indoor and outdoor channels throughout a broad spectrum of microwaveand millimeter-wave frequencies, the ci fs standard distance d0 = 1 m yields excellent parameter stability and model accuracy, as well develops a consistent modeling technique. setting a standard measure of 1 m for the near field of large antenna arrays reduces inaccuracy in wireless system design and is more achievable than the abg model given in [11]. the abg model is the second pl model. equation (16) by [11] provides the equation for the abg model. plabg(f, d)[db]⁡= 10α log10 ( d 1 m )⁡ ⁡+β + 10γ log10 ( f 1ghz ) + χ σ abg⁡⁡ )21…( (f, d)[db], d = 10 log10(d) and f = 10 abgb = pl the sf is given and ,are used log10(f) from (19) ]11[by χ σ abg = b − αd − β − γf. ⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡ …(22) the sf standard deviation ⁡⁡⁡𝜎abg = √∑ ⁡ 𝜒𝜎abg2 𝑁 = √ ∑ ⁡ (𝐵 − 𝛼𝐷 − 𝛽 − 𝛾𝐹)2 𝑁 ⁡ ⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡⁡. . . (23) the notation (f, d) [db] describes the pl at a certain frequency (f) and distance (d). this notation is used to signify the coefficients that indicate the dependency of pl on distance and frequency. similarly, the optimal compensation value for pl in db may be represented, where d indicates the distance between the transmitter and receiver, and f denotes the carrier frequency in gigahertz (ghz). to establish line-of-sight communication inside an urban environment, the parameters α, β and are carefully chosen. the values of the parameters are shown in the following bracket. { ∝= 1 𝛽 = 69.4 𝛾 = 2 for simulations, the distance, d, between the transmitter and receiver is set at 100 m, and the frequency, f, is set at (28–60) ghz. the ci model in equation (15) contains a single parameter and a frequency dependency of pl. the frequencydependent fspl term is the main way to represent its frequency dependency. the abg models’ three parameters, namely, alpha, beta and gamma, depend on several factors in addition to frequency (equation 16) [22-26]. the ci model’s frequency dependency is mainly indicated by the frequency-dependent fspl component in the initial meter of free-space zinah.o.dawood al-khwarizmi engineering journal, vol. 21, no.1, pp. 7088 (2025) 93 propagation, whereas the abg and ci models with d0 = 1 m are functions of range and frequency. in the indoor office situation, recent data reveal that the pl rises with frequency throughout the mm wave range (the β and γ parameters are used for curve fitting). when the abg model includes an enhancement parameter β and a frequency weighting term γ, which lack an established scientific basis, it departs from physics. a reference distance of 1 m is used to calculate the term in the abg model. 2. proposed system model to increase bit error rate (ber), two pl models (abg and ci) are utilised between the transmitter and reception antenna. the proposed system model is illustrated in figure 1. it is based on a w-ofdm system rather than a normal ofdm system. first, bits of stream are utilised as an input and transmit only one binary bit of information. the next stage involves modulating a high-frequency carrier signal with digital information. demodulation, or the opposite of modulation, occurs at the receiving end. two modulation schemes (16-qam and 16-psk) are employed. two types of pl models (abg and ci) are utilised between the transmitter and reception antennas to reduce ber. the suggested system model is displayed in figure 1. fig. 1. proposed 4×4 mimo system model for ber reduction utilising pl models 3. results and descussion table 1, parameters of the simulated model in brief table 2, parameters in the ci path loss model (δσ discrepancy in the standard deviation of sf between the ci and ci at d0 = 10) 2022a matlab version 12800 binary bits message typ 28 ghz ghz 60 operating frequency )f( 60 khz carrier spacing 48 mbps data rate 20 mhz bandwidth 4×4 antenna configuration 1 m d0 size 256 ifft / fft )ght(line of si los frequency range (ghz) distance )m( model path loss exponent (ple) d0 )m ( (db) σ δ σ 28 100–300 ci model 2 1 m 1,3 0 28 100–300 ci model 2 10 m 1,3 38 100–300 ci model 2,1 1m 1,4 0,1 38 100–300 ci model 2,1 10m 1,3 48 100–300 ci model 2,1 1m 1,1 0,1 48 100–300 ci model 2,1 10m 1 60 100–300 ci model 2 1m 0.6 0 60 100–300 ci model 2 10m 0,6 zinah.o.dawood al-khwarizmi engineering journal, vol. 21, no.1, pp. 7088 (2025) 94 table 3, parameters in the abg path loss model (δσ difference in the standard deviation sf between the abg and abg at d0 = 10) los )tghline of si( frequency range )ghz( distance )m( model α β 𝛄 (m)d0 (db) σ δ σ 28 300–100 abg model 1 69,4 2 m1 4 0 28 300–100 abg model 1 69,4 2 m10 4 38 300–100 abg model 1 69,4 2 m1 4 0 38 300–100 abg model 1 69,4 2 10m 4 48 300–100 abg model 1 69,4 2 m1 4 0 48 300–100 abg model 1 69,4 2 m10 4 60 300–100 abg model 1 69,4 2 m1 3.9 0 60 300–100 abg model 1 69,4 2 10m 3.9 table 4, parameters in the ci and the abg path loss models (δσ difference in the standard deviation sf between the ci and abg at d0 = 10) fig. 2. ci pl model for the 4×4 mimo at 28 ghz frequencies and complex indoor room scenario fig. 3. normal distribution of pl model for the 4×4 mimo at 28 ghz frequencies and complex indoor room scenario nlos (nonline of sight) frequency range in )ghz( distance )m( model path loss exponent (ple) α (𝐀𝐁𝐆) β (𝐀𝐁𝐆) 𝛄 (𝐀𝐁𝐆) d0in meter σ(db) for ci model σ(db) for abg model δ σ=( σ(db) ci σ(db)for abg) 28 300 ci model 2 1 69.4 2 10m 4.1 0.1 28 300 modelabg 1 69.4 2 10m 4 38 300 ci model 2 1 69.4 2 10m 4.9 0.2 38 300 abg model 1 69.4 2 10m 4.7 48 300 ci model 2 1 69.4 2 10m 4.9 0 48 300 abg model 1 69.4 2 10m 4.7 60 300 ci model 2.1 1 69,4 2 10m 5 0.1 60 300 abg model 1 69,4 2 10m 4.7 zinah.o.dawood al-khwarizmi engineering journal, vol. 21, no.1, p.p. 8999 (2025) 95 fig. 4. ci pl model for the 4×4 mimo at 60 ghz frequencies and complex indoor room scenario fig. 5. normal distribution of pl model for the 4×4 mimo at 60 ghz frequencies and complex indoor room scenario fig. 6. abg pl model for the 4×4 mimo at 28 ghz frequencies and complex indoor room scenario fig. 7. normal distribution of pl model for the 4× 4 mimo at 28 ghz frequencies and complex indoor room scenario zinah.o.dawood al-khwarizmi engineering journal, vol. 21, no.1, p.p. 8999 (2025) 96 fig. 8. abg pl model for the 4×4 mimo at 60 ghz frequencies and complex indoor room scenario fig. 9. normal distribution of pl model for the 4×4 mimo at 60 ghz frequencies and complex indoor room scenario 4. conclusion this paper uses collections of measured data from 28 ghz to 60 ghz to examine and contrast two large-scale propagation route loss models, namely, abg (three elements) and the ci (two elements), over the mm wave frequency ranges. initially, the 1 m ci model and the ci model with a reference distance = 10 are compared. the twoparameter 1 m ci model yields about equal accuracy. the results demonstrate that on the one hand, in the presence of data sets, the prediction accuracies of the abg and ci models are extremely comparable despite the abg model’s need for additional model parameters and absence of a physical foundation for its floating-intercept value. on the other hand, the ci model is physically connected to the transmitter power by using a 1meter ci fs reference distance, which has a built-in frequency dependency over the whole mm wave range. in contrast to the physically based ci with fewer model parameters, the abg model has parameter values that vary substantially over various distances and frequencies whilst typically only slightly lowering the sf standard deviation. a collection of data points is given, and the single largest difference between the standard deviations for two models across all situations is (2.7) db for the mm wave range. nevertheless, a more recent research [12] using a considerably larger data set reveals a mere 0.4 db difference in an outdoor case. this paper demonstrates using a 28 ghz for example how the abg nlos model is naturally inaccurate at short and long (several hundred m) distances. it also underestimates interference at long distances when applied at an arbitrary frequency in comparison to ci and predicts less than free space loss when near the tx. thus, capacity simulations generated by the abg model are extremely optimistic. the simulation findings between the abg and ci models differ considerably, particularly with regard to planned small-cell deployments where interference might be produced by hundreds of nearby bss. the paper’s key contribution is a sensitivity analysis that demonstrates that the ci model outperforms the others in terms of stability and prediction accuracy (i.e. sf standard deviation) over a wide range of frequencies. the ci model performs than the abg model when applied to forecasting pl at various distances and frequencies compared with the data set used to identify the pl models’ parameters. therefore, 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[10] t. s. rappaport, s. sun, and m. shafi, "5g channel model with improved accuracy and efficiency in mmwave bands," ieee 5g tech focus, vol. 1, no. 1, pp. 1-6, 2017. [11] s. sun et al., "investigation of prediction accuracy, sensitivity, and parameter stability of large-scale propagation path loss models for 5g wireless communications," ieee transactions on vehicular technology, vol. 65, no. 5, pp. 2843-2860, 2016. [12] l. lu, g. y. li, a. l. swindlehurst, a. ashikhmin and r. zhang, "an overview of massive mimo: benefits and challenges," in ieee journal of selected topics in signal processing, vol. 8, no. 5, pp. 742-758, oct. 2014. [13] [13] n. a. muhammad, p. wang, y. li, and b. vucetic, "analytical model for outdoor millimeter wave channels using geometrybased stochastic approach," ieee transactions on vehicular technology, vol. 66, no. 2, pp. 912-926, 2016. [14] [14] a. a. budalal and m. r. islam, "path loss models for outdoor environment—with a focus on rain attenuation impact on short-range millimeter-wave links," e-prime-advances in electrical engineering, electronics and energy, vol. 3, p. 100106, 2023. [15] [15] s. f. nawaf, "channel capacity improvement of mimo communication systems using different techniques," tikrit journal of engineering sciences, vol. 25, no. 1, pp. 36-41, 2018 [16] j. lu, and h. b. zhu, "stochastic multiple‐input multiple‐output channel model based on singular value decomposition," iet communications, vol. 9, no. 15, pp. 18521856, 2015. [17] o. o. erunkulu, a. m. zungeru, c. k. lebekwe, and j. m. chuma, "cellular communications coverage prediction techniques: a survey and comparison," ieee access, vol. 8, pp. 113052-113077, 2020. [18] w. lu and m. di renzo, "stochastic geometry modeling and system-level analysis & optimization of relay-aided downlink cellular networks," ieee transactions on zinah.o.dawood al-khwarizmi engineering journal, vol. 21, no.1, p.p. 8999 (2025) 98 communications, vol. 63, no. 11, pp. 40634085, 2015. [19] t. bai, r. vaze, and r. w. heath, "analysis of blockage effects on urban cellular networks," ieee transactions on wireless communications, vol. 13, no. 9, pp. 50705083, 2014. [20] s. sun, g. r. maccartney, and t. s. rappaport, "a novel millimeter-wave channel simulator and applications for 5g wireless communications," in 2017 ieee international conference on communications (icc), 2017: ieee, pp. 1-7. [21] m. j. da silva, d. c. begazo, and d. z. rodríguez, "evaluation of speech quality degradation due to atmospheric phenomena," in 2019 international conference on software, telecommunications and computer networks (softcom), 2019: ieee, pp. 1-6. [22] l. f. abdulameer, u. sripati, and m. kulkarni, "ber performance improvement of dual chaotic maps based on stbc communication system," al-khwarizmi engineering journal, vol. 18, no. 4, pp. 32-44, 2022. [23] m. shafi et al., "microwave vs. millimeterwave propagation channels: key differences and impact on 5g cellular systems," ieee communications magazine, vol. 56, no. 12, pp. 14-20, 2018. [24] a. a. h. budalal, m. r. islam, k. abdullah, and t. a. rahman, "modification of distance factor in rain attenuation prediction for short-range millimeterwave links," ieee antennas and wireless propagation letters, vol. 19, no. 6, pp. 1027-1031, 2020. [25] z. a. shamsan, "rainfall and diffraction modeling for millimeter-wave wireless fixed systems," ieee access, vol. 8, pp. 212961-212978, 2020. [26] a. a. budalal, i. m. rafiqul, m. h. habaebi, and t. a. rahman, "the effects of rain fade on millimetre wave channel in tropical climate," bulletin of electrical engineering and informatics, vol. 8, no. 2, pp. 653-664, 2019. [27] i. shayea, t. abd. rahman, m. hadri azmi, and a. arsad, "rain attenuation of millimetre wave above 10 ghz for terrestrial links in tropical regions," transactions on emerging telecommunications technologies, vol. 29, no. 8, p. e3450, 2018. )2025( 89-99، صفحة 1، العدد21مجلة الخوارزمي الهندسية المجلد زينة اسامة داود 99 نماذج فقدان المسار لنظام االتصاالت الالسلكية الجيل الخامس باستخدام قناة اتصال الموجات الملمترية زينة اسامة داود جامعة بغداد، بغداد، العراققسم هندسة المعلومات واالتصاالت، كلية الهندسة الخوارزمي، zina_osama@kecbu.uobaghdad.edu.iqالبريد االلكتروني: لمستخلص ا )متعددة المدخالت والمخرجات المتعددة( في أنظمة االتصاالت الالسلكية زيادة سعة القناة والموثوقية. يعد استخدام mimoيمكن لطوبولوجيا هوائي رة وأجهزة الذكاء نطاقات تردد الموجات المليمترية جنبا إلى جنب مع التقنيات األخرى خطوة مهمة في تحقيق معدالت بيانات عالية للوسائط المتعددة المتطو لي ، فإن اعي. ومع ذلك ، فإن إرسال إشارات تردد الموجة المليمترية يواجه تحديات مثل التالشي وتأخير الوقت واالنتشار وفقدان التشتت. وبالتااالصطن ير نماذج فقدان المسار تحسين معلمات االنتشار أمر بالغ األهمية لتحسين األداء. تبحث هذه الدراسة في تأثير نماذج فقدان المسار تبحث هذه الدراسة في تأث )pl( (abg وci على تصميم وتحليل نظام )4×4 ofdm-mimo w 16باستخدام تقنية التشكيل-qam .لالتصاالت الالسلكية من الجيل الخامس ي واالنحراف لتقييم فقدان المسار بالديسيبل والتوزيع الطبيع abg plو pl ciباستخدام نموذجي ofdm-mimo wتفحص الورقة البحثية أنظمة مرن للغاية وفعال في استرجاع qam-16مع التشكيل الرقمي ci plالقائم على نموذج ofdm-mimo wالمعياري. ووفقًا لنتائج المحاكاة، فإن نظام اإلشارات المرسلة. mailto:zina_osama@kecbu.uobaghdad.edu.iq path loss models for 5g wireless communication system using mm wave communication channel zinah o. dawood department of information and communication engineering, al-khwarizmi engineering college, university of baghdad, baghdad, iraq email: zina_osama@kecbu.uobaghdad.edu.iq abstract multiple-input multiple-output (mimo) antenna topologies in wireless communication systems can increase channel capacity and dependability. the use of millimeter (mm)-wave frequency bands in conjunction with other technologies is a substantial step in... keywords: mimo; millimeter wave; path loss; abg model; two-parameter ci model 1. introduction the increasing need for wide availability of data and improved mobile data speeds has led to a decrease in the available spectrum within the conventional frequency bands utilised for wireless communication, that is, a frequency lower than 6 ghz. fifth... 1.1.channel models underlying (single_input, single_output, siso, mimo) wireless channels are classified as largeand small-scale propagation effects (largeand small-scale fading, respectively). path loss (pl) and shadowing effects caused by great distances are the major causes of large-scale fading. by contrast, ... 1.2. mimo system mimo technology may improve system capacity without increasing bandwidth or broadcast power by increasing the number of transmitting and receiving antennas. the transmitter antenna n and the reception antenna m can gather the signal given by the [1]. y=hx+n, …(1) where y is the received signal, and h is a matrix is used to deal with transmitted signal x and noise n over the whole channel. assuming equal rayleigh channel matrices and average power allocation, the mimo system’s capacity may be expressed in the e... where the sent signal x, where bi, det, in. the first parameter to be determined is the bandwidth allocated to each user. next, the determinant of the given matrix needs to be calculated. in conclusion, determining the identity of the matrix represent... the equation of the matrix used to deal with transmitted signal is given by [15] .𝑯=, ,,ℎ-1,1.-,ℎ-1,2.-…-,ℎ-1,𝑁.-,ℎ-2,1.-,ℎ-2,2.-…-,ℎ-2,𝑁.-…-…-⋱-…-,ℎ-𝑀,1.-,ℎ-𝑀,2.-…-,ℎ-𝑀,𝑁... … (3) as previously shown, each individual component of the rayleigh channel matrix may be interpreted as follows by [16]: ,h-i,j.=α+jβ=,,α-2.+,β-2..,e-,jarctan-,β-α...=,,h-i,j..,e-j,ϕ-i,j..…(4) where α,β is a rayleigh distributed random variable, and |h (i,j) |are random distributed variables. the expression of h (i,j) may be expressed below. the rayleigh channels are the independent and identically distributed complex zero mean and unit en... ,h-i,j.=,normal-,0,,1-,2....+,jnormal-,0,,1-,2.... …(5) where the normal distribution is generated by normal. as a result, h (i,j) conforms to the ,𝑥-2-2. distribution using two degrees of freedom that e= ,,ℎ-𝑖,𝑗..=1. because the eigenvalue of ,𝐼-𝑁.+,𝑝-𝑚.,𝐻𝐻-𝐻 .is produced by the determination equation, the capacity can be calculated by primarily using the eigenvalue of ,𝐻𝐻-𝐻. considering the eigenvalues of the two matrices : ,𝐴𝑝×𝑞,𝐵𝑞×𝑝,𝑝≤𝑞. eigenvalue of are ,𝐴𝐵-𝑃×𝑃 . and,𝐵𝐴-𝑞×𝑞. equal. because a zero eigenvalue does not contribute to the capacity effect, the eigenvalues of hhh and hhh are the same, and λ=,λ-1,. ,𝜆-2,………. .,,𝜆-min⁡(𝑁,𝑀).provides the nonzero eigenvalues of the b. the equation for the capacity is given by [16]. b=,,h,h-ii.,m<n,-,h-h.h,m>n... …(6) the mimo capacity in this case may be expressed as follows: 𝐶=,i=1-m- .,b-i.,,log-2.-,,det-,,𝐈-n.+,ρ-m.𝐇,𝐇-h..... = ,i=1-m- .,b-i.,,log-2.-,,i=1-,min-,n,m..- . ,1+,ρ-m.,λ-i-2.... … (7) mimo capacity analysis frequently employs singular value decomposition (svd). the channel matrix in svd is broken down by the following: 𝐻=𝑈𝐷,𝑉-𝐻. …(8) when d is a matrix with the dimensions m by n, u and v are unitary matrices with the dimensions m by m and n by n, respectively, whose nonzero norm by the diagonal components is equal to the singular values of h. thus, equation (1) may be expressed a... 1.3.from mimo to mm mimo massive mimo, in combination with other technologies such as as small cells, (hetnets) and (mm wave) technology, is positioned to play a remarkable role in the development of 5g networks, which are now working to deal with the issues given by the tran... 1.4. free space propagation model the assumption that underpins the model of propagation in free space is that the surrounding environment is clear of any interference or impediments. thus, elements such as reflection, refraction and other effects of a similar kind are not account... ,,p-r.-,p-t..=,,,g.-4πd. λ. … (10) in the context of free space transmission, the variables pr, pt, g, λ and d represent the received power, transmitted power, product of the transmitter and receiver antenna field radiation patterns, wavelength, and distance between the transmitter and... fspl=20l,og-10.,d.+20l,og-10.,,4π-c.. … (11) where the operational frequency starts at f = 28 ghz, and the distance between the transmitter and receiver is d = (100–300 m). the two pl models for better comparability are also considered. the close in free space (ci fs) reference distance pl mod... ,f,d.,db.=plfs,f,,d-0..,db.+10 n ,log-10.,,d-,d-0... …(12) the loss of fs propagation at a distance = 1 m equation now becomes, given by [5]. ,,, pl-ci.-,f,d..,db.=,fspl-,f,,d-0..,db..--+10n,,log-10.-,,d-,d-0....+,χ-σ-ci., where d≥,d-,0 -.. . …(16) where n is the path loss exponent (ple), χci is the ci fs reference distance, and f is also expressed in gigahertz (for the ci). with a standard deviation measured in db, σ represents a zero-mean gaussian random variable. to determine the mean pl with... ,fspl-,f,,d-0..,db..=20,,log-10.-,,4πf,d-0.×,10-9.-c... … (17) ,,pl-ci.(f,d)[db]=-fspl,f,,d-0..[db]+10n,log-10.⁡,d/,d-0..+,χ-σ-ci.-=-10n,log-10.⁡,,d-,d-0...+20,log-10.⁡,,4π,d-0.×,10-9.-c..-+20,log-10.⁡(f)+,χ-σ-ci.-=-10n,log-10.⁡,,d-,d-0...+η+20,log-10.⁡(f)+,χ-σ-ci.,-where d≥,d-0., η=20,,log-10.-,,,4π,d-0.×,10... ,,χ-σ-ci.=,pl-ci.(f,d)[db]−fspl⁡(f,1 m)[db]−10n,log-10.⁡(d)-=a−nd …(19). ,σ-ci.=,,, .,χ-σ-cl., -2.-n..=,,, .(a−nd,)-2.-n. . …(20) ,,pl-abg.(f,d)[db]=10α,,log-10.-,,d-1 m... -+β+10γ,,log-10.-,,f-1ghz...+,χ-σ-abg. . …(21) ,χ-σ-abg.=b−αd−β−γf. …(22) the sf standard deviation for simulations, the distance, d, between the transmitter and receiver is set at 100 m, and the frequency, f, is set at (28–60) ghz. the ci model in equation (15) contains a single parameter and a frequency dependency of pl. the frequency-dependent fs... the abg models’ three parameters, namely, alpha, beta and gamma, depend on several factors in addition to frequency (equation 16) [22-26]. 2. proposed system model to increase bit error rate (ber), two pl models (abg and ci) are utilised between the transmitter and reception antenna. the proposed system model is illustrated in figure 1. it is based on a w-ofdm system rather than a normal ofdm system. first,... fig. 1. proposed 4×4 mimo system model for ber reduction utilising pl models 3. results and descussion fig. 8. abg pl model for the 4×4 mimo at 60 ghz frequencies and complex indoor room scenario fig. 9. normal distribution of pl model for the 4×4 mimo at 60 ghz frequencies and complex indoor room scenario 4. conclusion references [1] j. g. andrews, f. baccelli, and r. k. ganti, "a tractable approach to coverage and rate in cellular networks," ieee transactions on communications, vol. 59, no. 11, pp. 3122-3134, 2011. [2] m. di renzo, c. merola, a. guidotti, f. santucci, and g. e. corazza, "error performance of multi-antenna receivers in a poisson field of interferers: a stochastic geometry approach," ieee transactions on communications, vol. 61, no. 5, pp. 2025-20... [3] m. di renzo, a. guidotti, and g. e. corazza, "average rate of downlink heterogeneous cellular networks over generalized fading channels: a stochastic geometry approach," ieee transactions on communications, vol. 61, no. 7, pp. 3050-3071, 2013. [4] m. di renzo and w. lu, "the equivalent-in-distribution (eid)-based approach: on the analysis of cellular networks using stochastic geometry," ieee communications letters, vol. 18, no. 5, pp. 761-764, 2014. [5] m. h. mahmud, k. khaleduzzaman, s. sarker, and l. c. paul, "effect of path loss models on performance of 5g compatible mimo window-ofdm systems," in 2020 international conference on smart technologies in computing, electrical and electronics (icst... [6] f. di stasio, m. mondin, and f. daneshgaran, "multirate 5g downlink performance comparison for f-ofdm and w-ofdm schemes with different numerologies," in 2018 international symposium on networks, computers and communications (isncc), 2018: ieee, p... [7] j. park, h.-b. jeon, j. cho, and c.-b. chae, "measurement-based close-in path loss modeling with diffraction for rural long-distance communications," ieee wireless communications letters, 2023. [8] m. k. elmezughi and t. j. afullo, "investigations into the effect of high-ordering the log-distance dependency of path loss models for indoor wireless channels," international journal on communications antenna and propagation, vol. 12, no. 1, pp. ... [9] m. di renzo, "stochastic geometry modeling and analysis of multi-tier millimeter wave cellular networks," ieee transactions on wireless communications, vol. 14, no. 9, pp. 5038-5057, 2015. [10] t. s. rappaport, s. sun, and m. shafi, "5g channel model with improved accuracy and efficiency in mmwave bands," ieee 5g tech focus, vol. 1, no. 1, pp. 1-6, 2017. [11] s. sun et al., "investigation of prediction accuracy, sensitivity, and parameter stability of large-scale propagation path loss models for 5g wireless communications," ieee transactions on vehicular technology, vol. 65, no. 5, pp. 2843-2860, 2016. [12] l. lu, g. y. li, a. l. swindlehurst, a. ashikhmin and r. zhang, "an overview of massive mimo: benefits and challenges," in ieee journal of selected topics in signal processing, vol. 8, no. 5, pp. 742-758, oct. 2014. [13] [13] n. a. muhammad, p. wang, y. li, and b. vucetic, "analytical model for outdoor millimeter wave channels using geometry-based stochastic approach," ieee transactions on vehicular technology, vol. 66, no. 2, pp. 912-926, 2016. [14] [14] a. a. budalal and m. r. islam, "path loss models for outdoor environment—with a focus on rain attenuation impact on short-range millimeter-wave links," e-prime-advances in electrical engineering, electronics and energy, vol. 3, p. 100106, 2023. [15] [15] s. f. nawaf, "channel capacity improvement of mimo communication systems using different techniques," tikrit journal of engineering sciences, vol. 25, no. 1, pp. 36-41, 2018 [16] j. lu, and h. b. zhu, "stochastic multiple‐input multiple‐output channel model based on singular value decomposition," iet communications, vol. 9, no. 15, pp. 1852-1856, 2015. [17] o. o. erunkulu, a. m. zungeru, c. k. lebekwe, and j. m. chuma, "cellular communications coverage prediction techniques: a survey and comparison," ieee access, vol. 8, pp. 113052-113077, 2020. [18] w. lu and m. di renzo, "stochastic geometry modeling and system-level analysis & optimization of relay-aided downlink cellular networks," ieee transactions on communications, vol. 63, no. 11, pp. 4063-4085, 2015. [19] t. bai, r. vaze, and r. w. heath, "analysis of blockage effects on urban cellular networks," ieee transactions on wireless communications, vol. 13, no. 9, pp. 5070-5083, 2014. [20] s. sun, g. r. maccartney, and t. s. rappaport, "a novel millimeter-wave channel simulator and applications for 5g wireless communications," in 2017 ieee international conference on communications (icc), 2017: ieee, pp. 1-7. [21] m. j. da silva, d. c. begazo, and d. z. rodríguez, "evaluation of speech quality degradation due to atmospheric phenomena," in 2019 international conference on software, telecommunications and computer networks (softcom), 2019: ieee, pp. 1-6. [22] l. f. abdulameer, u. sripati, and m. kulkarni, "ber performance improvement of dual chaotic maps based on stbc communication system," al-khwarizmi engineering journal, vol. 18, no. 4, pp. 32-44, 2022. [23] m. shafi et al., "microwave vs. millimeter-wave propagation channels: key differences and impact on 5g cellular systems," ieee communications magazine, vol. 56, no. 12, pp. 14-20, 2018. [24] a. a. h. budalal, m. r. islam, k. abdullah, and t. a. rahman, "modification of distance factor in rain attenuation prediction for short-range millimeter-wave links," ieee antennas and wireless propagation letters, vol. 19, no. 6, pp. 1027-1031, 2... [25] z. a. shamsan, "rainfall and diffraction modeling for millimeter-wave wireless fixed systems," ieee access, vol. 8, pp. 212961-212978, 2020. [26] a. a. budalal, i. m. rafiqul, m. h. habaebi, and t. a. rahman, "the effects of rain fade on millimetre wave channel in tropical climate," bulletin of electrical engineering and informatics, vol. 8, no. 2, pp. 653-664, 2019. [27] i. shayea, t. abd. rahman, m. hadri azmi, and a. arsad, "rain attenuation of millimetre wave above 10 ghz for terrestrial links in tropical regions," transactions on emerging telecommunications technologies, vol. 29, no. 8, p. e3450, 2018. نماذج فقدان المسار لنظام الاتصالات اللاسلكية الجيل الخامس باستخدام قناة اتصال الموجات الملمترية زينة اسامة داود قسم هندسة المعلومات والاتصالات، كلية الهندسة الخوارزمي، جامعة بغداد، بغداد، العراق البريد الالكتروني: zina_osama@kecbu.uobaghdad.edu.iq المستخلص يمكن لطوبولوجيا هوائي mimo (متعددة المدخلات والمخرجات المتعددة) في أنظمة الاتصالات اللاسلكية زيادة سعة القناة والموثوقية. يعد استخدام نطاقات تردد الموجات المليمترية جنبا إلى جنب مع التقنيات الأخرى خطوة مهمة في تحقيق معدلات بيانات عالية للوسائط المتعدد... this is an open access article under the cc by license: an improved prosthesis for through ankle joint amputation 2yassr y. kahtan ,*1 noon kadhim rasheed 1,2 department of prosthetics and orthotics engineering, college of engineering, al-nahrain university, baghdad,iraq *corresponding author’s e-mail: noonkadom96@gmail.com (received 9 april 2023; revised 29 september 2023; accepted 4 october 2023; published 1 december 2024) https://doi.org/10.22153/kej.2024.10.006 abstract prosthetics through the ankle joint are prescribed to patients with a symes amputation after rehabilitation. energy can be stored and discharged from the flexible parts, such as the foot, leg and joints of the prostheses. this work improves the prosthetics for amputation through the ankle joint by providing the prosthetics with a movable ankle joint. the most important achievement of the ankle joint is that it performs important walking movements, the most important being planter flexion, dorsiflexion, inversion and eversion. a movable ankle joint was suggested and modelled in the solidwork program, and it was analysed using the finite element method to evaluate stresses and deformations. this model was used to improve a patient’s gait and reduce exertion. the suggested ankle joint was evaluated through several experimental tests, such as the ground reaction force (grf) test, 6 min walking test and range of motion test. all the results indicate an improvement in gait parameters and patient adaptation to the suggested ankle-joint prosthetic. the grf test showed the behaviour of the normal state approaches when using the suggested ankle-joint prosthetic. the results of the grf test illustrate the percentage difference in the forces for the healthy limb from the suggested movable prosthetic and thetraditional one, with approximate values of 10.96% and 38.88%, respectively. calculation revealed that the weight of the movable prosthetic with the suggested ankle joint was reduced by 32.69% compared with traditional prosthetic. in addition, a questionnaire was conducted to determine the extent of patient satisfaction when the moving prosthetic was used for a certain period. the questionnaire presented a considerable improvement in patient comfort and other aspects compared with the traditional prosthetic. keywords: prosthetic, amputation, eversion, inversion, ankle joint, solid work, suggested prosthetic 1. introduction prostheses restore body parts lost due to trauma, genetic defects or other causes [1]. these parts allow amputees to have a normal work and social life [2]. amputation changes a person, from being a healthy individual into one with a disabled body and hurt. this condition causes sadness, pain and poor energy when interacting with the society, which causes difficulty in adaption [3]. walking is one of the basics of daily life necessary for everyone. however, this movement is a complex functional process that involves the combination of muscles and tendons. a person can move from one place to another while keeping his body image balanced and stable. walking is difficult for those with amputated lower limbs. the development of the lower extremities is aimed at improving the image of walking through modern and advanced innovative mechanisms [4]. comprehending the functioning of prostheses is necessary to identify foot movements: eversion (ev)–inversion (in), dorsiflexion (df) and plantar flexion (pf) [5] (figure 1). al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 20, no. 4, december (2024), pp. 13-24 mailto:noonkadom96@gmail.com https://doi.org/10.22153/kej.2024.10.006 noon kadhim al-khwarizmi engineering journal, vol. 20, no.4, p.p. 1324 (2024) 14 fig. 1. different foot movements [6] ruben c. martinez, et al. (2014) [7] designed an ankle joint for bk amputation with a one-way spring. this spring is meant to store and release energy to aid in toe movement. the weight of the joint can be reduced by changing its component materials. positive results were obtained in walking while using the joint, but difficulty in standing, sitting and ascending and descending stairs remained. these issues will all be fixed in the future. eric nickel et al. (2014) [8] developed a foot-and-ankle model by making a flat foot plate with a thickness of 10 mm from nylon 6/6 with a black crepe layer for cushioning and a rubber layer for guaranteed high stability while walking on sloping ground. in addition, the foot was provided with an annular bottom arch to form a natural rocking shape for the ankle to walk at ground level. the low rigidity of the pf and neutralisation were achieved using a polyurethane rubber bumper (compensating absorber) placed inside the keel ring. according to the initial mechanical test, this stiffness was sufficient to reduce the pf velocity (reducing foot slap), with which positive results were obtained in downhill walking. pierre cherelle et al. (2017) [9] proposed an ankle joint design with an mechanism of locking and unlocking four columns by pushing them out of position against the mechanical stop. at this point, the necessary torque is produced during the early stopping phase when the leg’s action compresses the pf springs. to recover the maximum amount of energy from walking, scholars have added additional locking mechanisms to amp-foot 3, such as the natural capability to adapt to different walking speeds and incline and improved energy storage during early standing. experiments involving climbing hills and walking on flat ground were conducted. dianbiao dong, et al. (2017) [10] designed a new energy mechanical ankle joint using a five-bar spring mechanism due to its flexibility during various special foot movements in walking. the most important of these movements include pf and df without restriction. in the future, the act of walking on various terrains must be developed. the ankle joint was suggested due to its importance in performing the crucial movements used for walking. this work aimed to design an ankle joint that is suitable for ankle joint amputation, comfortable while walking, low cost and easy to use and maintain and provides important walking movements (pf, df, in and ev). 2. numerical analysis modelling of ankle joint using solidworks program an ankle joint design consisting of two pieces, with one attached to the foot and the other to the socket, was proposed. the first model was designed for the ankle joint, and the lateral opening was oval to perform movements (in and ev). the joint was designed and manufactured using the solid work 2018 program. the design failed because it did not activate these movements, which when applied realistically failed to meet the requirements. the function appeared in walking. figure 2 shows the upper part and figure 3, the lower part. all the dimensions are in millimeters (mm). fig. 2. upper part of the suggested ankle joint noon kadhim al-khwarizmi engineering journal, vol. 20, no.4, p.p. 1324 (2024) 15 fig. 3. lower part of the ankle joint another two-piece ankle joint design with a ball end bolt was proposed (figure 4). the lateral holes assume a circular shape to allow movements of df and the plantar muscles (figure 5). the upper hole connected to the socket of the prosthesis has an oval shape with a bolt fixation, and the middle oval hole promotes lateral movements (figure 6). fig. 4. beam for the ankle joint design fig. 5. lower part of the ankle joint noon kadhim al-khwarizmi engineering journal, vol. 20, no.4, p.p. 1324 (2024) 16 fig. 6. upper part of the ankle joint the final form of the suggested ankle joint was manufactured from aluminum in cnc vector 610 at the university of technology (figure 7). figure 8 shows the final assembly for the suggested ankle joint and foot. fig. 7. assembly of the designed suggested ankle joint fig. 8. final assembly for the suggested ankle joint with foot 3. finite element analysis (fea) often substantive in the phrasing of formulated equations is the use of mechanics samples to solve the command equation of a known phenomena and the capability to predict deterministic and various phenomena in the fields of science and engineering. numerical styles have been adopted to remove difficult-to-eliminate sacrificial solutions from equations. among these numerical styles, fea approximates continuity with an infinite degree of freedom by a discrete body. the finite element method has become a powerful instrument for finding numerical solutions of a vast range of engineering problems [11]. ansys–19 was adopted to generate the finite element model (figure 9). table 1. mechanical properties of the parts of movable prosthetic (the suggested ankle joint). mechanical properties bolt ankle joint foot material stainless steel aluminum alloy carbon fibre tensile ultimate strength (mpa) 586 310 345 tensile yield strength (mpa) 207 280 230 young modulus (gpa) 193 71 395 passion ratio 0.31 0.33 0.2 noon kadhim al-khwarizmi engineering journal, vol. 20, no.4, p.p. 1324 (2024) 17 fig. 9. ankle joint in ansys-19 software 4. design and manufacture of the ankle joint after designing the joint in the solid work program, it was implemented in real life. a piece of aluminum 7075 metal was purchased (20 * 25 cm2), and an x-ray fluorescence test was carried out to determine its material contents and the percentage of each. the joint was manufactured at the university of technology, in the laboratories and workshops section, turning department (in a machine; vector 610) (figures 10 and11). fig. 10. cnc machine vector 610 and aluminum block fig. 11. final design shape of the ankle joint the ankle joint was assembled using screws, with the addition of springs and a piece of rubber, to enable the necessary movements and absorbance of energy (storage and waste of energy) during the stance phase and push off (figures 12 and 13). fig. 12. ankle joint components fig. 13. bolts; the first is half tooth and the other is smooth figure 14 shows the connection of the joint with the foot and socket. fig. 14. final shape of the prosthetic the bolt nut connects every two parts with each other. however, the nut was dispensed in a manner that made the bolt half smooth and half serrated (figure 15), with the teeth of the pieces to which it was attached to making it like a nut to prevent the addition extra weight when adding nuts. the mathematical equations below were applied: noon kadhim al-khwarizmi engineering journal, vol. 20, no.4, p.p. 1324 (2024) 18 fig. 15. bolts the tension stress (figure 16), and stress bearing can be calculated using the following: σ = f a where σ: stress bearing (pa), f: tensile load in the axial direction (n) and a: sectional area= 2td (mm) the bolt shear (figure 17) can be calculated as follows: τ = f a where τ: shear stress (pa), f: shear load (n) and a: sectional area = πd²/4 (mm) fig. 16. tension load of bolt fig. 17. bearing joint 5. results and discussions 5.1 numerical simulation conducted using fea results numerical analysis was carried out using the workbench ansys-19 software to determine stress analysis results, deformation and safety factors. force (900 n) was applied on the bolt and surface of the upper part of the suggested ankle joint (figure 18). fig. 18. applied force in ansys software the following steps were suitable for the fea when using the ansys program. the ankle joint was analysed in the static structure by applying load on the top of the ankle joint for two cases (heel strike and toe off), by making the fixation the base for the entire foot in one and by making the fixation only with the heel and toes in another. heel-strike phase ansys analysis numerical analysis was conducted to determine the stresses and deformations expected to occur during heel strike. when fixation was at the base of the entire foot, and the angle of force was 20°, the von mises stress reached 17.292 mpa, and the total deformation was 0.015158 mm (figures 19 and 20, respectively). on the other hand, when the fixation was only at the foot heel, the von mises stress reached 26.49 mpa, and the total deformation was 0.057475 mm (figures 21 and 22, respectively). fig. 19. von mises stress in heel strike of the wholefoot fixed support noon kadhim al-khwarizmi engineering journal, vol. 20, no.4, p.p. 1324 (2024) 19 fig. 20. total deformation in heel strike of the whole-foot fixed support fig. 21. von mises stress in heel strike and heel fixed support fig. 22. total deformation in heel strike and heel fixed support toe-off phase ansys analysis numerical analysis was conducted to determine the stresses and deformations expected to occur during toe off. when fixation was at the base of the whole foot, and the angle of force was 40.5°, the von mises stress reached 21.326 mpa, and the total deformation was 0.015172 mm (figures 23 and 24, respectively). on the other hand, when fixation was only at the front of the foot, the von mises stress reached 38.62 mpa, and the total deformation was 0.063299 mm (figures 25 and 26, respectively). fig. 23. von mises stress in toe off for the whole-foot fixed support fig. 24. total deformation in toe off for the wholefoot fixed support fig. 25. von mises stress in toe off for front-foot fixed support fig. 26. total deformation in toe off for front-foot fixed support noon kadhim al-khwarizmi engineering journal, vol. 20, no.4, p.p. 1324 (2024) 20 the safety factor for all phases was 15 (figure 27). table 2. ansys program results fig. 27. safety factor table 2 contains the von mises stresses and total deformations for all phases. the minimum von mises stress applied was approximately 5 mpa, which was obtained in the standing phase. the highest von mises stress was approximately 38 mpa, which was obtained in the toe-off phase. this finding indicates that the stronger the movement, the higher the increase in the von mises stress values. 5.2 prosthetics weight the weight of the foot is approximately 23% of the foot length [12]. the weight of a traditional prosthetic for an amputation through the ankle is approximately 1.3 kg. the weight of the movable prosthetic with the suggested ankle joint is 875 g, with the weight of the socket at 500 g. the suggested ankle joint has a weight of 375 g (figure 28). fig. 28. a) weight of the movable prosthetic; b) weight of a traditional prosthetic the difference between the weight of the movable prosthetic with the suggested ankle joint and that of a traditional prosthetic was calculated as follows: ( 1.3 − 0.875 1.3 ) × 100 = 32.69 the weight of the movable prosthetic with the suggested ankle joint was reduced by 32.69% compared with that of the traditional prosthetic, which indicates an increase in patient comfort. 5.3 ground reaction force (grf) test results the grf test was conducted by a patient walking on the strength board in the rehabilitation laboratory at the department of orthotic and prosthetic engineering, al-nahrain university, once while wearing the traditional prosthesis with a fixed joint (figure 29) and then while wearing the prosthesis with a movable joint (figure 30). the test was performed thrice, and the patient rested for 2 min between each attempt. fixed support von mises stress (mpa) total deformation (mm) heel strike total foot 17.292 0.015158 heel strike heel 26.49 0.057475 toe off total foot 21.326 0.015172 toe off front foot 38.62 0.063299 a b amputee side sound side noon kadhim al-khwarizmi engineering journal, vol. 20, no.4, p.p. 1324 (2024) 21 fig. 29. grf curve results obtained when using the traditional prosthetic fig. 30. grf curves results obtained when using the movable prosthetic the results of the grf test for the first case (which is the traditional limb) were obtained. the force was higher in the amputated part than in the healthy ones, which shows the extent of the patient’s confusion in using the limb. the patient was attempting to reach the ground at a high speed due to fear of falling. the findings of the grf test for the second (which is the limb with a movable joint)were acquired. a convergence was observed in the peak force reached by the amputated and healthy parts, which indicates the extent of the patient’s comfort, balance and confidence when walking while wearing the limb with a movable ankle joint (table 3). table 3, maximum forces observed for both prosthetics. traditional prosthetic test moveable prosthetic test max. forces amputee side, n max. forces sound side, n max. forces amputee side, n max. forces sound side, n 1 472.76 336.5 6 417.55 453.29 2 468.90 286.5 7 317.14 356.19 3 464.68 264.7 5 405.62 449.92 amputee side sound side noon kadhim al-khwarizmi engineering journal, vol. 20, no.4, p.p. 1324 (2024) 22 table 3 shows the ratio of the change in the curve in relation to the sound and amputated sides. the results were compared with those observed when using the traditional prosthetic and the prosthetic limb with the suggested ankle joint (table 4). table 4, force ratio of traditional and moveable prosthetics type of prosthetic the force ratio % traditional prosthetic 38.88 movable prosthetic 10.96 the results of the grf test reveal that the percentage differences in the forces of the healthy limb from the (suggested) movable prosthetic and traditional prosthetics were approximately 10.96% and 38.88%, respectively. 5.4 results of ankle joint angle measurement the range of motion of the patient’s ankle joint was measured while wearing the prosthesis with the movable joint while walking and measured again in the standing phase (figure 31). fig. 31. ankle range of motion table 5 shows the degrees of special movements necessary for walking. table 5. ranges of motion of the manufactured ankle joint motion df pf in/ev normal range limits 20 deg. 20 deg. 5 deg. range limits for patient 20 deg. 50 deg. 12 deg. this indicates a closeness in the values of normal ankle joint motions compared with those of the manufactured ankle joint and fixed joint. 6. conclusions a two-piece ankle joint was suggested to provide important movements for walking (pf, df, in and ev). one of the pieces is attached to the foot and the other to the socket. bolts connect the pieces to each other. the upper hole of the piece connected to the socket is characterised by an oval shape for performing in and ev movements. the movable ankle joint was modelled using the solidwork program and analysed with the fea program. experimental tests were carried out to evaluate the acceptability of the prosthesis for the patient, and the following were observed: 1 . the designed prosthetic with a movable ankle joint is the best for performing movements necessary for walking functions because it was made to be lightweight (the weight of the movable prosthetic was 32.69% lower than that of a traditional prosthetic), inexpensive and small in size compared with a traditional prosthetic limb. the ankle joint was designed using the solidwork program, analysed with the fea program and then manufactured using a cnc machine. 2. the results obtained from the fea program indicate that the highest stress was 38 mpa in the toe-off phase, but it was obtained only when the front of the foot was connected to the ground. the least amount of stress (5 mpa) was reached in the standing phase. the whole-foot fixed support and safety factors in all cases were equal to 15. 3. from the grf test, when using the traditional prosthetic, instability was observed in the gait compared with the moving limb, which is close to a sound foot. according to the results of the grf test, the percentage difference in the forces for the sound limb from the (suggested) movable and traditional prosthetics were approximately 10.96% and 38.88%, respectively. the extent of the amputee’s comfort and satisfaction with the movable prosthesis was observed in the 6 min walking test with the prosthetic limb with a movable ankle joint and by measuring the stride length, step length and step width. 4. in general, the patient felt more satisfied while using the prosthesis with a movable ankle joint. abbreviations: pf planter flexion, df dorsiflexion, in inversion, ev eversion, rom range of motion, 6mwt six minute walking test, grf ground reaction force, fem finite element method noon kadhim al-khwarizmi engineering journal, vol. 20, no.4, p.p. 1324 (2024) 23 7. references [1] mohsin j. jweeg and jana s. jaffar, “vibration analysis of prosthesis for the through knee amputation”, al-nahrain university, college of engineering journal (nucej) vol.91 no.1, 2016. [2] stefano alleva, michele gabrio antonelli, pierluigi beomonte zobel and francesco durante, “biomechanical design and prototyping of a powered ankle-foot prosthesis”, materials journal, vol.13, 5806 ,doi:10.3390/ma13245806 , 2020. [3] anila viran, carol ewashen, jane werunga and teri green, “caring for patients with limb amputation”, nursing standard, vol.30, no.6 ,2015. [4] huong thi thu vu , dianbiao dong , hoanglong cao, tom verstraten , dirk lefeber , bram vanderborght and joost geeroms , “a review of gait phase detection algorithms for lower limb prostheses” , sensors journal, 20, 3972, doi:10.3390/s20143972, 2020. [5] joel zagoya-lópez, luis adrián zúñigaavilés, adriana h. vilchis-gonzález and juan carlos ávila-vilchis, “review foot/ankle prostheses design approach based on scientometric and patentometric analyses”, appl. sci. journal, vol.11, 5591, https://doi.org/10.3390/app11125591, 2021. [6] claire l. brockett and graham j. chapman, “biomechanics of the ankle”, national library medicine journal, vol.30(3):232-238 , 2016. [7] ruben c. martinez, roberto l. avitia, miguel e. bravo and marco a. reyna, “a low cost design of powered ankle-knee prosthesis for lower limb amputees preliminary results”, international conference on biomedical electronics and devices, dio:10.5220/0004914402530258, 2014. [8] eric nickel, jonathon sensinger and andrew hansen, “passive prosthetic ankle-foot mechanism for automatic adaptation to sloped surface”, journal of rehabilitation & development, vol. 51, no. 5, 2014. [9] pierre cherelle, victor grosu, louis flynn, karen junius, marta moltedo, bram vanderborght and dirk lefeber, “the ankle mimicking prosthetic foot 3 -locking mechanisms, actuator design, control and experiments with an amputee”, journal of robotics and autonomous systems, vol.91, 2017. [10] dianbiao dong, wenjie ge, shumin liu, fan xia and yuanxi sun, “design and optimization of a powered ankle-foot prosthesis using a geared five-bar spring mechanism”, international journal of advanced robotic systems, vol.10, dio: 10.1177/1729881417704545, 2017. [11] muslim muhsin ali, “design and analysis of a non-articulated prosthetic foot for people of special needs”, msc.thesis, nahrain university, 2010. [12] carina price and christopher nester, “foot dimensions and morphology in healthy weight, overweight and obese males clinical biomechanics”, centre for health science research, university of salford, salford, england, united kingdom, 2016. (2024) 13-24، صفحة 4، العدد20مجلة الخوارزمي الهندسية المجلدنون كاظم رشيد 24 تحسين الطرف الصناعي لبتر خالل مفصل الكاحل 2ياسر يعرب قحطان ،*1نون كاظم رشيد قسم هندسة االطراف والمساند الصناعية، كلية الهندسة، جامعة النهرين 2،1 noonkadom96@gmail.com: البريد اإللكتروني* المستخلص ( بعد عملية إعادة التأهي . يمكن تخزين الخاقة symesيعانون من بتر )يتم وصفففففر ا طراف االصفففففخناعية من لكا م صففففف الكا للمر ففففف ال ين للبتر من لكا وت ريغها من ا جزاء المرنة مث القدم والسفا وم اصف ا طراف االصفخناعية. وتتمث دا دة ه ا العم دي نح ي سفن ا طراف االصفخناعية لم صف الكا هو نح يدد ركا مهمة دي الميفي همها )انثناء م صف الكا من لكا تزويد ا طراف االصفخناعية بم صف كا مت رأ. هم إن ا وت ليلح باسفففتخدام solidworkالمصفففي ، عخر يهر ، انقكل للدال ، انقكل للخا. (. تم اقترات وتصفففميم م صففف الكا المت رأ دي برنام ين ميية المريض وتقلي ال هد المب وا. يتم تقييم م ص الكا المقترت من طريقة العناصر الم دودة لتقييم الضغوط والتيوها . يستخدم ه ا النموذ لت س ت سفففن دي لكا عدة التبا.ا ت ريبية مث التبا. قوة .د ال ع اال. فففي والتبا. سفففق دقا م ميفففي مسفففتمر والتبا. مدي ال ركة. تيفففير جمي النتا إل المقترت ، ويظهر التبا. قوة .د ال ع اال. ففي ن سففلوأ م صفف الكا يقترل من ال الة معايير الميففية وتكير المريض م م صفف الكا االصففخناعي وي للخرف الخبيعية عند اسفففتخدام م صففف الكا االصفففخناعي المقترت . و ففف ق نتا التبا. قوة .د ال ع اال. فففي ن النسفففبة الم وية لكلتكف دي الق ٪ عل التوالي. عند سفففال الو ن ، تيفففير ٣٨‚٨٨٪ ، ١٠‚٩٦والخرف االصفففخناعي التقليد والي السفففليم من الخرف االصفففخناعي المت رأ )المقترت( ٪ مقا.نةً با طراف الصففناعية التقليدية. باإل ففادة إل ٣٢‚٦٩النتا إل ن و ن الخرف االصففخناعي المت رأ م م صفف الكا المقترت انخ ض بنسففبة المريض عند اسففففتخدام الخرف االصففففخناعي المت رأ ل ترة من الزمن. قدم االسففففتبيان ت سففففنا كبيرا دي .ا ة ذلك ، تم إجراء اسففففتبيان لمعردة مدي . ففففا .ناعية التقليديةالمريض وال وانب ا لري لكستبيان بالمقا.نة م ا طراف الص mailto:noonkadom96@gmail.com https://doi.org/10.22153/kej.2024.10.006 3. finite element analysis (fea) this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 20, no. 1, march, (2024), p p. 6375 adaptive robust tracking control of robotic manipulator based on smc and fuzzy control strategy ali hussien mary* ahmad al-talabi** tolgay kara*** dina saadi muneam**** mohammad yahya almuhanna***** laith awda kadhim mayyahi****** *,****,***** department of mechatronics engineering/al-khwarizmi college of engineering/ university of baghdad/ baghdad/ iraq **department of medical instrumentation techniques engineering/ college of engineering and information technology / alshaab university/ baghdad/iraq *** gaziantep university/ türkiye ******carleton university / faculty of engineering and design/ ottawa/ canada corresponding author: *email: alimary76@kecbu.uobaghdad.edu.iq **email: ahmad.altalabi@alshaab.edu.iq ***email: kara@gantep.edu.tr ****email: deena@kecbu.uobaghdad.edu.iq ******email: mohammad.yahya@kecbu.uobaghdad.edu.iq ******email: laith.mayyahi@carleton.ca )received 22 august 2023; accepted 12 november 2023 published 1 march 2024( 002.11.4https://doi.org/10.22153/kej.202 abstract in recent years, robotic systems have been widely used in different applications, and this has motivated researchers to develop different control methods. a model-free, intelligent, robust control method for a nonlinear robotic manipulator system is proposed in this work. this paper presents a novel solution for the major drawbacks of the sliding mode control scheme, which are chattering. prior knowledge is needed about the dynamic model of the controlled system and the upper bound of uncertainty. in this paper, a fuzzy-like pd controller with smc (flpdsm) is proposed. the fuzzy-like pd controller was designed according to fuzzy rules and membership functions based on the nominal model of the robot manipulator. a robust control term was added to the control signal to compensate for the system uncertainty, and external disturbances are compensated by adding an auxiliary robust term to the smc control law. two methods for designing robust control terms are proposed. the first proposed method assumes that the upper bound of system uncertainty is known although it cannot be exactly determined due to external disturbances and uncertainty. hence, a second method was proposed that assumes this bound to be unknown, and an adaptive gain based on lyapunov theory was used to derive the adaptation law. the lyapunov second method was used to ensure the stability of the closed loop system. performance tests on the proposed methods were implemented through simulation studies for the two-link robotic manipulator, and the test results were compared with the standard smc to verify the effectiveness of the proposed method. a good trajectory tracking with a high robustness against parameter variations and external disturbances was observed under the presented control scheme. keywords: smc, robotic systems, fuzzy control, trajectory tracking. 1. introduction robotic manipulators are used successfully in many particular applications, and especially in industrial factories. accuracy and precision are important features that encourage the use of robotic manipulators in plants that aim to enhance their products and manufacturing processes [1]. there mailto:alimary76@kecbu.uobaghdad.edu.iq mailto:ahmad.altalabi@alshaab.edu.iq mailto:yahya@kecbu.uobaghdad.edu.iq mailto:laith.mayyahi@carleton.ca https://doi.org/10.22153/kej.2024.11.002 ali hussien mary al-khwarizmi engineering journal, vol. 20, no. 1, p.p. 6375 (2024) 64 are many challenges that make tracking accuracy in robotic manipulators difficult, including high nonlinearity, system uncertainties, and strong coupling between adjacent joints, hence, several control schemes have been proposed to solve these problems by designing a stable and robust controller. because of its simplicity in structure and the relatively easy tuning of parameters, the proportional integral derivative (pid) controller is applied in different control system [2]. fuzzy logic was used to schedul of the pid controller to control the hybrid robot manipulator [3]. fuzzy type 2 had been proposed for the control of the 2dof robotic manipulator with grey wolf optimization used for tuning the parameters [4]. the particle swarm optimization method was combined with the pid controller to stabilize the humanoid robot [5] . an adaptive backstepping control with a simple adaptive estimated lyapunov theorem has been used for the control of the robotic manipulator [6]. many advanced control schemes, including adaptive and artificial intelligence methods, have been used to tune the parameters of the pid. the number of degrees of freedom and system uncertainties of the robotic manipulator have significant effects on control performance. the sliding mode control (smc) represents an efficient control scheme for nonlinear systems, that is applied successfully in many mechanical systems and robotic manipulators. chattering is the major disadvantage of smc and different control schemes have been proposed to eliminate the chattering. among the solutions to the chattering problem in the smc is the use of saturation approximation functions instead of the discontinues function, and low-pass filtering [712]. recently, the fuzzy logic technique has been widely applied to approximate the signum discontinues term [13-18]. implementing the smc control law requires the upper bound of the uncertainties, and the external disturbance must be known [19]. the values of these bounds are very important in the selection of the switching gain. to ensure stability, the switching gain must be greater than the upper bound of uncertainty, which is unknown, and assuming large values for the upper bound may be the reason for chattering. this paper presents two robust control schemes based on fuzzy control and smc. the important features of the proposed controller in this paper can be summarized as follows: i) the upper bound of uncertainty is not required, ii) the proposed controller is model-free, iii) lyapunov theory is used to avoid the overestimation of the switching gain, construct an adaptation law for the switching gain, and also guarantee the stability of the controlled system. 2. robotic manipulator dynamic the dynamic equations of n rigid-link robotic manipulator system based on the lagrange-euler equations of motion are: 𝑀(𝑞)�̈� + 𝐶(𝑞, �̇�)�̇� + 𝐹(�̇�) + 𝐺(𝑞) + 𝜏𝑑 = … (1) 𝑀(𝑞) = 𝑀𝑜(𝑞) + ∆𝑀(𝑞) …(2) 𝐶(𝑞, �̇�) = 𝐶𝑜(𝑞, �̇�) + ∆𝐶(𝑞, �̇�) …(3) 𝐹(�̇�) = 𝐹𝑜(�̇�) + ∆𝐹(�̇�) …(4) where q = [𝑞1, 𝑞2, ⋯ , 𝑞𝑛]𝑇 ∈ rn is the joint angular position vector, q̇ = [�̇�1, �̇�2, ⋯ , �̇�𝑛]𝑇 ∈ rn is the joint angular velocity vector, m(q) ∈ rnx n denotes the inertia matrix, c(q, q̇) ∈ rnx n represents the centrifugal-coriolis matrix,f(q̇) ∈ rn is the friction torque vector, g(q) ∈ rn denotes the gravity term, τd ∈ rn is the external disturbance vector, and τ = [𝜏1, 𝜏2, ⋯ , 𝜏𝑛]𝑇 is the torque vector. mo(q), co(q, q̇) and fo(q̇) refer to the nominal model of the robotic manipulator, and ∆m(q),∆c(q, q̇) and ∆f(q̇) refer to the uncertainty in the dynamic model of the robotic manipulator. the proposed control method assumes the following [ 20]: assumption 1: boundedness of the inertia matrix ‖𝑀(𝑞)‖ ≤ 𝑘1 …(5) where 𝑘1 is a positive scalar. assumption 2: boundedness of the centrifugal matrix ‖𝐶(𝑞, �̇�)‖ ≤ 𝑘2 …(6) where 𝑘2 is a positive scalar. assumption 3: boundedness of the friction vector ‖𝐹(�̇�)‖ ≤ k3‖q̇‖ + f0 …(7) where 𝑘3 and 𝐹0 are positive scalars. assumption 4: boundedness of the gravity vector ‖𝐺(𝑞)‖ ≤ 𝑘4 …(8) where 𝑘4 is a positive scalar. assumption 5: the model in (1) is linearly parameterized, so it can be represented by the following expression: y∅ = m(q)q̈r + c(q, q̇)q̇r + g(q) + f(q̇) …(9) �̇�𝑟 = �̇�𝑑 + 𝛾(𝑞𝑑 − 𝑞) …(10) where y = y(q, q̇, q̇r, q̈r) ∈ rn×p is a matrix that contains a known nonlinear function, ∅ ∈ rp is a vector that contains unknown parameters, and 𝛄 is a positive diagonal matrix. assumption 6: the desired trajectories and their derivativesqd(𝑡),q̇d(𝑡), and q̈d(𝑡)are bounded as follows: |𝑞𝑑(𝑡)| ≤ 𝑀𝑑1 , |�̇�𝑑(𝑡)| ≤ 𝑀𝑑2 , |�̈�𝑑(𝑡)| ≤ 𝑀𝑑3, …(11) with 𝑀𝑑1, 𝑀𝑑2, and 𝑀𝑑3being positive constants. ali hussien mary al-khwarizmi engineering journal, vol. 20, no. 1, p.p. 6375 (2024) 65 3. sliding mode control the objective of smc is to make trajectory states 𝐪track the desired trajectory𝐪𝐝. the first step in the smc is designing the sliding surface. for a second-order system, the sliding surface is given by: 𝑠(𝑡) = 𝛾 𝑒(𝑡) + �̇�(𝑡) …(12) 𝑒(𝑡) = 𝑞 − 𝑞𝑑 …(13) 𝑒(𝑡) = [𝑒1(𝑡) 𝑒2(𝑡) ⋯ 𝑒𝑛(𝑡)]𝑇 …(14) where 𝐞(𝑡)is the error signal that represents the difference between the desired trajectory and the actual trajectory. an equivalent control term in the conventional smc is calculated by setting �̇�(𝑡) = 0 , and this will determine the control effort required to achieve a good performance without considering the external disturbance and system uncertainties. ṡ(𝑡) = γė(𝑡) + ë(𝑡) …(15) = γė(𝑡) + q̈ − q̈d …(16) q̈ = m−1(q)[τ − c(q, q̇)q̇ − f(q̇) − g(q) − τd] …(17) where 𝛄is a diagonal matrix. in the equivalent control term, only the known part of the dynamic model of the controlled system is taken into account, which yields: �̇�(𝑡) = 𝛾 �̇�(𝑡) + 𝑀𝑜 −1(𝑞)[𝜏 − 𝐶𝑜(𝑞, �̇�)�̇� − 𝐹𝑜(�̇�) − 𝐺𝑜(𝑞)] …(18) �̇�(𝑡) = 0 …(19) γ ė(t) + mo −1(q)[τeq − co(q, q̇)q̇ − fo(q̇) − go(q)] = 0 …(20) 𝜏𝑒𝑞 = 𝐶𝑜(𝑞, �̇�)�̇� − 𝐹𝑜(�̇�) − 𝐺𝑜(𝑞) + 𝑀𝑜(𝑞)𝛾 �̇�(𝑡) …(21) however, the equivalent control term is not sufficient to achieve good performance in practical applications due to many challenges like parameter variations and external disturbances. a control law is presented to compensate for these uncertainties. the overall smc control signal is: τ = τ𝑒𝑞 + τ𝑟 …(22) τ𝑟 = 𝑘 𝑠𝑔𝑛(s) = [𝑘1𝑠𝑔𝑛(𝑠1) ⋯ 𝑘𝑛𝑠𝑔𝑛(𝑠𝑛)]𝑇 …(23) 𝑠𝑔𝑛(𝑠𝑖) = { 1 𝑖𝑓 𝑠𝑖 > 0 −1 𝑖𝑓 𝑠𝑖 < 0 …(24) where 𝛕𝒓 is the robust term and the value of k is large and must be greater than the upper bound of uncertainty. there are many challenges to implementing the control law of the conventional smc. as shown in (21), the exact dynamic mode of the robotic system and the upper bound of uncertainty must be known to select the gain of the robust term. moreover, the sign function causes the chattering phenomena that may cause damage to the actuators. 4. proposed flpdsm design this section discusses in detail the two terms of the proposed control method. figure 1 displays the block diagram for the proposed control scheme. the proposed control law is: τ = τ𝐹 + τ𝑟 …(25) where 𝛕𝑭 is the output of the fuzzy-like pd controller that was designed based on the nominal model of the robotic system, and 𝛕𝒓refers to the robust control signal that overcomes the uncertainties and external disturbances that were not included in the fuzzy-like pd controller’s design. two methods are proposed for the robust control term𝛕𝒓 : in the first method, the upper bound of the dynamic model of the robotic system is assumed to be known, while in the second method, this bound is assumed to be unknown. 4.1 fuzzy-like pd controller a fuzzy-like pd controller is proposed to achieve good performance with fuzzy rules, and was designed without considering parameter variations, and external disturbances. only the nominal model of the robot manipulator is considered. the inputs to the fuzzy controller are the normalized error and the derivative of the error. the output of the fuzzy controller is τ𝐹 . τ𝐹 = kf𝑢𝑓 …(26) 𝑢𝑓(𝑡) = 𝐹𝑃𝐷(𝑒(𝑡), �̇�(𝑡)) …(27) ali hussien mary al-khwarizmi engineering journal, vol. 20, no. 1, p.p. 6375 (2024) 66 fig. 1. basic decentralized control scheme for two link robotic manipulator. where 𝒌𝒇 is a positive diagonal matrix that refers to the output scaling factor, and 𝐹𝑃𝐷(𝒆(𝑡), �̇�(𝑡))denotes the fuzzy logic decision system. the membership functions for the input variables 𝒆(𝑡) and �̇�(𝑡) and the output variable𝒖𝒇(𝑡) are shown in figure 2. five fuzzy functions, defined as negative big (nb), negative small (ns), zero (z), positive small (ps), and positive big (pb), are used as membership functions. table 1 lists the rules used in this controller. the intersection minimum has been used for the fuzzification process, while the center average operations were used for defuzzification. fig. 2. membership functions for the fuzzy controller table 1, fuzzy controller rules 𝒆(𝒕) �̇�(𝒕) nb ns z ps pb nb nb nb nb ns z ns nb nb ns z ps z nb ns z ps pb ps ns z ps pb pb pb z ps pb pb pb 4.2 robust auxiliary controller any robust control scheme must take into account parameter variations and external disturbances in order to provide a controller that is robust to unpredictable variations. in this section, two methods are presented to select a suitable auxiliary controller. in the first proposed method, the upper bound of uncertainty is assumed to be known, while in the second proposed method, it assumed to be unknown. 4.2.1 proposed i: constant switching gain in this method, the switching gain, whose value is determined based on lyapunov theory, is kept constant, as shown in figure 3. 𝛕𝒓 = 𝒌 𝑠𝑔𝑛 (𝐬) = [𝑘1𝑠𝑔𝑛(𝑠1) ⋯ 𝑘𝑛𝑠𝑔𝑛(𝑠𝑛)]𝑇 …(28) the proposed control law can be written as: τ = 𝑘𝑓𝑢𝑓 + 𝑘 𝑠𝑔𝑛(s) …(29) theorem 1 considering the nonlinear robotic system in (1), and the proposed robust fuzzy control method in (29), the closed loop system will be asymptotically stable with approximately zero error signals if the controller parameters are selected as follows: ‖k‖ > ‖y∅ + 𝑘𝑓‖ …(30) 𝑘𝑓 > 0 …(31) proof. let 𝑉 be the candidate lyapunov function used to verify the stability. 𝑉 = 1 2 s𝑇ms …(32) �̇� = s𝑇mṡ + 1 2 s𝑇ṁs = s𝑇mṡ + s𝑇cs …(33) �̇� = s𝑇[m(q)q̈r + c(q, q̇)q̇r + g(q) + f(q̇) − τ] …(34) �̇� = s𝑇[y∅ − τ] …(35) gc 1 𝑞1𝑑 + 𝜏2 𝑞2 𝜏1 𝑞1 robotic manipulator 𝑞2𝑑 gc 2 + -1 -0.5 0 0.5 1 0 0.2 0.4 0.6 0.8 1 d e g re e o f m e m b e rs h ip nb ns z ps pb 𝑒(𝑡) , �̇�(𝑡) , 𝑢𝑓 ali hussien mary al-khwarizmi engineering journal, vol. 20, no. 1, p.p. 6375 (2024) 67 �̇� = s𝑇[y∅ − τf − τr] …(36) �̇� = s𝑇[y∅ − 𝑘𝑓𝑢𝑓 − τ𝑟] …(37) the outputs of the fuzzy controller are normalized between [-1, 1], then ‖uf‖ ≤ 1 …(38) s𝑇𝑘𝑓uf ≤ ‖s‖‖kf‖ …(39) �̇� ≤ ‖s‖[‖y∅‖ − ‖k‖ + ‖kf‖] …(40) fig. 3. block diagram for the proposed scheme i (constant robust gain). �̇� ≤ ‖s‖[‖y∅‖ + ‖kf‖ − ‖k‖] …(41) if k is selected based on the following condition: ‖k‖ > ‖y∅‖ + ‖kf‖ …(42) then �̇� ≤ 0 …(43) thus, the closed loop system is asymptotically stable. remark: the problem is that the upper bound of the robotic system dynamic (𝐘∅) is not exactly known and is related to the upper bound of uncertainty. selecting a larger value for 𝐤 will cause chattering, and a smaller value may make the system unstable. a second method was proposed to overcome this problem. 4.2.2 proposed ii: adaptive gain to avoid the problem of the unknown upper bound of the dynamic model of the robotic system, lyapunov’s theorem is applied to design an adaptation law for the gain of the robust term to estimate the upper bound of the robot dynamic. as a result, there is no need to know the upper bound of the dynamic model, which is related to the upper bound of system uncertainty and external disturbance, which cannot be easily determined in practical applications. figure 4 shows the second proposed method. let 𝜌 = y∅ − 𝑘𝑓𝑢𝑓 …(44) 𝝆cannot be determined exactly because it’s based on dynamic of the robot manipulator. the proposed robust control is: τ𝑟 = 𝜌 ...(45) where �̂� represents estimation of 𝝆 . then the estimation error can be defined as: �̃� = 𝜌 − 𝜌 … (46) the proposed control law is: τ = 𝑘𝑓uf + 𝜌 ...(47) theorem 2 if the control law in (46) is used for the nonlinear robotic manipulator in (1), then the controlled system will be asymptotically stable with zero error signals if the parameters �̂� are adjusted by the following adaptation law: �̇̃� = −𝐿𝑇 −1 𝑠 …(48) 𝜌(𝑡) = ∫ �̇̃�(𝑡) 𝑡 𝑡−1 𝑑𝑡 + 𝜌(𝑡 − 1) …(49) where 𝐋 ∈ r𝑛×𝑛 is the adaptation rate. ali hussien mary al-khwarizmi engineering journal, vol. 20, no. 1, p.p. 6375 (2024) 68 fig. 4. block diagram for the proposed scheme ii (adaptive robust gain). proof. let let 𝑉be the candidate lyapunov function. 𝑉 = 1 2 s𝑇ms + 1 2 �̃�𝑇l�̃� …(50) �̇� = s𝑇mṡ + 1 2 s𝑇ṁs + �̇̃�𝑇l�̃� …(51) = s𝑇mṡ + s𝑇cs + �̇̃�l�̃� …(52) s𝑇[m(q)q̈r + c(q, q̇)q̇r + g(q) + f(q̇) − τ] + �̇̃�𝑇l�̃� …(53) �̇� = s𝑇[y∅ − 𝑘𝑓uf − τr] + �̇̃�𝑇l�̃� …(54) �̇� = s𝑇[𝜌 − 𝜌] + �̇̃�𝑇l�̃� …(55) �̇� = s𝑇[�̃�] + �̇̃�𝑇l�̃� …(56) �̇� = [s𝑇 + �̇̃�𝑇l]�̃� …(57) if �̇̃� = −𝐿𝑇 −1 s …(58) then �̇� = 0 …(59) as a result, the adaptation law for the control parameter 𝜌(𝑡)will be as follows: 𝜌(𝑡) = ∫ �̇̃�(𝑡) 𝑡 𝑡−1 𝑑𝑡 + 𝜌(𝑡 − 1) …(60) thus, the controlled system with the proposed method is asymptotically stable with zero tracking error. 5. simulation results in this section, a two-link rigid planar robotic manipulator system is used to illustrate the robustness and effectiveness of the presented method. figure 5 shows the schematic diagram of the two-link planar robotic manipulator, with the dynamic model expressed as follows: [ 𝜏1 𝜏2 ] = [ 𝑀11 𝑀12 𝑀12 𝑀22 ] [ �̈�1 �̈�2 ] + [ −𝑏�̇�2 −𝑏�̇�1 − 𝑏�̇�2 −𝑏�̇�1 0 ] [ �̇�1 �̇�2 ] + [ 𝑣1�̇�1 𝑣2�̇�2 ] + [ 𝑝1𝑠𝑔𝑛(�̇�1) 𝑝2𝑠𝑔𝑛(�̇�2) ] + [ 𝑔1 𝑔2 ] …(61) with 𝑀11 = 𝐼1 + 𝐼2 + 𝑚1𝐿𝑐1 2 + 𝑚2(𝐿𝑐2 2 + 𝐿1 2 + 2𝐿1𝐿𝑐2𝑐𝑜𝑠(𝑞2))𝑀12 = 𝐼2 + 𝑚2(𝐿𝑐2 2 + 𝐿1𝐿𝑐2cos (𝑞2)) 𝑀22 = 𝐼2 + 𝑚2𝐿𝑐2 2, 𝑏 = 𝑚2𝐿1𝐿𝑐2sin (𝑞2), 𝑔1 = 𝑚1𝐿𝑐1𝑔𝑐𝑜𝑠(𝑞1) + 𝑚2𝑔(𝐿𝑐2𝑐𝑜𝑠(𝑞1 + 𝑞2) + 𝐿1𝑐𝑜𝑠(𝑞1)), 𝑔2 = 𝑚2𝑔𝐿𝑐2𝑐𝑜𝑠(𝑞1 + 𝑞2). where 𝑞1 and 𝑞2 are angular positions, 𝜏1 and 𝜏2 are torques, 𝐿1 and 𝐿2 are lengths, 𝑚1 and 𝑚2 are masses, 𝐼1and𝐼2 are lengthwise centroid inertia, 𝐿𝑐1 and 𝐿𝑐2 are distances from the joint to the center of gravity, 𝑣1 and 𝑣2 are coefficients of viscous friction, and 𝑝1 and 𝑝2 are coefficients of dynamic friction of link1 and link2, respectively. the parameters of the two-link robotic manipulator used in the current simulation study are listed in table 2. in order to prove its effectiveness, the proposed control scheme is compared with the ali hussien mary al-khwarizmi engineering journal, vol. 20, no. 1, p.p. 6375 (2024) 69 standard smc. table 3 lists the values of the parameters of the proposed controllers and the smc that are used in the simulation. the integral time absolute error (𝐼𝑇𝐴𝐸) performance index is used for the comparison, which was used to numerically evaluate the performance of the tracking error. 𝐼𝑇𝐴𝐸 = ∫ 𝑡|𝑒(𝑡)|𝑑𝑡 𝑡𝑓 0 …(62) fig. 5. schematic diagram of two linkobotic system. table 2, robotic manipulator parameters 5.1 robustness test: model uncertainties the robustness and effectiveness of the presented control methods are examined in the presence of the model of uncertainties and compared with the smc. the system uncertainty includes variations in the mass, static, and dynamic coefficients of friction of link1 as well as link2. these parameters are increased by 15% of their nominal values. the desired trajectory used in this simulation is given as: 𝑞1𝑑(𝑡) = −0.1 + cos (2𝜋𝑡) …(63) 𝑞2𝑑(𝑡) = 0.5 + 𝑠𝑖𝑛 (2𝜋𝑡) …(64) the itae values for the proposed method i, proposed method ii, and smc are listed in table 4. to illustrate the comparison, variations in the itae for link1 and link2 are shown in figure 6. this comparison indicates that the itae for the proposed method ii is less than for the other methods, whereas the itae for the proposed method i and smc are approximately equal which means that the proposed method ii is more robust than the smc and the proposed method i. figures 7 and 8 show the tracking position, tracking error, and input torque for link1 and link2, respectively. these figures clearly indicate that the proposed control methods have very good tracking performance and smaller position tracking errors in link1 and link2. however, with respect to the chattering problem, figures 7 (c) and 8 (c) show that the control signals of proposed methods i and ii are significantly smoother than that of the smc. table 3, the parameters of proposed and smc controllers x y i,1m 1l 1 ,2m 2i 2l q 2q mp c2i c1i 1l 2l parameter link1 link2 mass (kg) 1.0 1.0 length (m) 1.0 1.0 viscous friction coefficient 0.1 0.1 ddynamic friction coefficient 0.1 0.1 lengthwise centroid inertia (kg m2) 0.5 0.5 distance from joint to center of gravity (m) 0.2 0.2 control method law parameter link1 link2 proposed ii τ = 𝑘𝑓 𝑢𝑓 + �̂� �̇̂� = 𝐿−1𝑠𝑇 𝑠(𝑡) = 𝛾 𝑒(𝑡) + �̇�(𝑡) 𝑘𝑓 250 250 𝐿 1 1 𝛾 5 5 proposed i τ = 𝑘𝑓 𝑢𝑓 + 𝑘 𝑠𝑎𝑡(𝑠, ∅) 𝑘𝑓 250 250 𝑘 300 300 ∅ 0.05 0.05 smc 𝑢 = 𝑀0(𝑞)�̈�𝑟 + 𝑁0(𝑞)�̇�𝑟 + 𝐺0 (𝑞) + 𝐻0(𝑞) + 𝑘1𝑠𝑎𝑡(𝑠, ∅) �̇�𝑟(𝑞) = �̇�𝑑 − 𝛾(𝑞 − 𝑞𝑑 ) 𝑠(𝑡) = 𝛾𝑒(𝑡) + �̇�(𝑡) 𝑘1 400 400 ∅ 0.05 0.05 𝛾 5 5 ali hussien mary al-khwarizmi engineering journal, vol. 20, no. 1, p.p. 6375 (2024) 70 fig. 6. itae variations for model uncertainties table 4, performance index itae values for model uncertainties fig. 7. angular position (a), tracking error (b), and input torque (c) of link1 under model uncertainties 0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 proposed ii proposed i smc link1 link2 proposed ii proposed i smc link1 0.0483 0.0648 0.0645 link2 0.0552 0.0551 0.0556 ali hussien mary al-khwarizmi engineering journal, vol. 20, no. 1, p.p. 6375 (2024) 71 5.2 robustness test: disturbance rejection this section discusses the robustness of the proposed controller in the case of an external disturbance when applied to the controller output for link1 and link2. the disturbance signals 𝑑1(𝑡) and 𝑑2(𝑡) that were applied respectively, on link1 and link2 are: 𝑑1(𝑡) = 9𝑠𝑖𝑛(5𝑡), 𝑑2(𝑡) = 9sin (7𝑡) …(65) the desired trajectory used in this simulation is given as: 𝑞1𝑑(𝑡) = 𝑞2𝑑(𝑡) = sin(2𝜋𝑡) … (66) the itae values are listed in table 5. the itae variations for all methods are also shown in figure 9, which indicates the clear superiority of proposed method ii. the simulation results for this case are shown in figures 10 and 11. the results obtained show a fast response of the proposed and smc methods with good tracking performance. the results also clearly indicate the superiority of the proposed method ii in comparison with the smc and the proposed method i. moreover, the adaptation technique that was used to estimate the upper bound of the dynamic model eliminates the chattering. therefore, the control signal of the proposed method ii is very smooth. fig. 8. angular position (a), tracking error (b), and input torque (c) of link2 under model uncertainties ali hussien mary al-khwarizmi engineering journal, vol. 20, no. 1, p.p. 6375 (2024) 72 fig. 9. itae variations for adding external disturbance table 5, performance index itae values for disturbance rejection. fig. 10. angular position (a), tracking error (b), and input torque (c) of link1 subjected to external disturbance 0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 proposed ii proposed i smc link1 link2 0 0.5 1 1.5 2 2.5 3 3.5 4 -1.5 -1 -0.5 0 0.5 1 1.5 p o s it io n (r a d ) ideal position proposed ii smc proposed i 0 0.5 1 1.5 2 2.5 3 3.5 4 -1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 e rr o r( ra d ) proposed ii smc proposed i 0 0.5 1 1.5 2 2.5 3 3.5 4 -200 -100 0 100 200 300 tr o q u e ( n m ) time(s) proposed ii smc proposed i proposed ii proposed i smc link1 0.0493 0.0655 0.0653 link2 0.0590 0.0613 0.0633 ali hussien mary al-khwarizmi engineering journal, vol. 20, no. 1, p.p. 6375 (2024) 73 fig. 11. angular position (a), tracking error (b), and input torque (c) of link2 subjected to external disturbance. 6. conclusion this paper proposes an adaptive fuzzy robust control system for robotic manipulators. two robust controllers are proposed for the two cases in which the upper bound of the dynamic model is known, and the upper bound is unkown. the proposed intelligent, robust, and model-free control scheme based on flc can be applied successfully in practical applications due to its simplicity in structure. it combines the robustness of the smc and an intelligent adaptation of the flc. the lyapunov theorem is used to approve the stability of the controlled system with the proposed control method and estimate the upper bound of the dynamic model. the simulation results show the effectiveness of the proposed control methods and indicate the superiority of the proposed method in the response to model uncertainty and external disturbance. references [1] jasim, h. h., mary, a. h., & ahmed, m. s. (2021). robust computed torque control for uncertain robotic manipulators. alkhwarizmi engineering journal, 17(3). [2] kara, t., & mary, a. h. (2018). robust trajectory tracking control of robotic manipulators based on model-free pid-smc approach. journal of engineering research, 6(3). [3] han, j., shan, x., liu, h., xiao, j., & huang, t. (2023). fuzzy gain scheduling pid control of a hybrid robot based on dynamic characteristics. mechanism and machine theory, 184, 105283. [4] gaidhane, prashant j., et al. "design of gaidhane, p. j., nigam, m. j., kumar, a., & pradhan, p. m. (2019). design of interval type2 fuzzy precompensated pid controller applied ali hussien mary al-khwarizmi engineering journal, vol. 20, no. 1, p.p. 6375 (2024) 74 to two-dof robotic manipulator with variable payload. isa transactions, 89, 169-185. [5] kashyap, a. k., & parhi, d. r. (2021). particle swarm optimization aided pid gait controller design for a humanoid mai, t., & tran, h. (2023). an adaptive robust backstepping improved control scheme for mobile manipulators robot. isa transactions, 137, 446456. [6] tseng, m. l., & chen, m. s. (2010). chattering reduction of sliding mode control by low‐pass filtering the control signal. asian journal of control, 12(3), 392-398. [7] feng, y., han, f., & yu, x. (2014). chattering free full-order sliding-mode control. automatica, 50(4), 1310-1314. [8] chaudhary, k. s., & kumar, n. (2023). fractional order fast terminal sliding mode control scheme for tracking control of robot manipulators. isa transactions. [9] hasan, s. k., & dhingra, a. k. (2022). development of a sliding mode controller with chattering suppressor for human lower extremity exoskeleton robot. results in control and optimization, 7, 100123. [10] kara, t., & mary, a. h. (2017). adaptive pdsmc for nonlinear robotic manipulator tracking control. studies in informatics and control, 26(1), 49-58. [11] sun, z., hu, s., xie, h., li, h., zheng, j., & chen, b. (2023). fuzzy adaptive recursive terminal sliding mode control for an agricultural omnidirectional mobile robot. computers and electrical engineering, 105, 108529. [12] wu, g., zhang, x., zhu, l., lin, z., & liu, j. (2021). fuzzy sliding mode variable structure control of a high-speed parallel pnp robot. mechanism and machine theory, 162, 104349. [13] zaare, s., & soltanpour, m. r. (2022). adaptive fuzzy global coupled nonsingular fast terminal sliding mode control of n-rigidlink elastic-joint robot manipulators in presence of uncertainties. mechanical systems and signal processing, 163, 108165. [14] wu, x., & huang, y. (2022). adaptive fractional-order non-singular terminal sliding mode control based on fuzzy wavelet neural networks for omnidirectional mobile robot manipulator. isa transactions, 121, 258-267. [15] lian, r. j. (2013). enhanced adaptive greyprediction self-organizing fuzzy sliding-mode controller for robotic systems. information sciences, 236, 186-204. [16] sadati, n., & talasaz, a. (2006). variable structure control with adaptive fuzzy sliding surface. journal of vibration and control, 12(11), 1251-1270. [17] li, p., ma, j., & zheng, z. (2016). robust adaptive sliding mode control for uncertain nonlinear mimo system with guaranteed steady state tracking error bounds. journal of the franklin institute, 353(2), 303-321. [18] mary, a. h., & kara, t. (2016). robust proportional control for trajectory tracking of a nonlinear robotic manipulator: lmi optimization approach. arabian journal for science and engineering, 41, 5027-5036. (2024) 63-75، صفحة 1، العدد20المجلد جلة الخوارزمي الهندسيةمعلي حسين مري 75 واستراتيجية التحكم التحكم المتين لذراع االنسان االلي بناء على طريقة الوضع المنزلق الغامض ****دينا سعدي منعم تولكاي كارار*** احمد عبد عطية** مري*علي حسين ليث عودة كاظم****** محمد يحيى ادريس***** العراق /جامعة بغداد /كلية الهندسة الخوارزمي /قسم هندسة الميكاترونكس *****،****،* العراق /جامعة الشعب /كلية الهندسة وتكنولوجيا المعلومات /الطبية** قسم تقنيات األجهزة تركيا / ***جامعة غازي عنتاب كلية الهندسة كندا /جامعة كارلتون ****** kecbu.uobaghdad.edu.iq76alimary@ :البريد االلكتروني* ahmad.altalabi@alshaab.edu.iq :االلكتروني* البريد * kara@gantep.edu.tr :* البريد االلكتروني** deena@kecbu.uobaghdad.edu.iq :البريد االلكتروني **** .yahya@kecbu.uobaghdad.edu.iqmohammad:البريد االلكتروني ****** laith.mayyahi@carleton.ca:البريد االلكتروني ****** الخالصة م المختلفة. في السنوات األخيرة، تم استخدام األنظمة الروبوتية على نطاق واسع في تطبيقات مختلفة، وهذا ما حفز الباحثون على تطوير أساليب التحك الرئيسة لنظام التحكم في يُقترح في هذا العمل طريقة تحكم ذكية وقوية وخالية من النماذج لنظام مناور آلي غير خطي. تقدم هذه الورقة حالً جديدًا للعيوب تم اقتراح وحدة تحكم الوضع المنزلق، هنالك حاجة إلى معرفة مسبقة حول النموذج الديناميكي للنظام المتحكم فيه والحد األعلى من عدم اليقين. في هذا البحث، pd معsmc (flpdsm) وتم تصميم وحدة التحكم .pd م . وتمت إضافة مصطلح تحكم متين إلى إشارة اعتمادا على المعلومات المتوافرة عن النظا . وتم اقتراح smcالتحكم للتعويض عن عدم اليقين في النظام، ويتم تعويض االضطرابات الخارجية عن طريق إضافة مصطلح قوي مساعد إلى قانون التحكم عدم اليقين في النظام معروف على الرغم من أنه ال يمكن تحديده بدقة طريقتين لتصميم شروط التحكم القوية. تفترض الطريقة األولى المقترحة أن الحد األعلى ل على نظرية بسبب االضطراب الخارجي وعدم اليقين. ومن ثم تم اقتراح طريقة ثانية تفترض أن هذا الحد غير معروف، وتم استخدام الكسب التكيفي القائم الثانية لضمان استقرار نظام الحلقة المغلقة. تم تنفيذ اختبارات األداء على الطرق المقترحة من ليابونوف الشتقاق قانون التكيف. تم استخدام طريقة البونوف القياسي للتحقق من فعالية الطريقة المقترحة. وقد لوحظ تتبع مسار smcخالل دراسات المحاكاة للمناول اآللي ثنائي الوصلة، وتمت مقارنة نتائج االختبار مع ختالفات المعلمات واالضطرابات الخارجية في إطار مخطط التحكم المقدم.جيد بمتانة عالية ضد ا mailto:alimary76@kecbu.uobaghdad.edu.iq mailto:ahmad.altalabi@alshaab.edu.iq mailto:kara@gantep.edu.tr mailto:deena@kecbu.uobaghdad.edu.iq mailto:yahya@kecbu.uobaghdad.edu.iq 1. introduction 2. robotic manipulator dynamic 3. sliding mode control 4. proposed flpdsm design 4.1 fuzzy-like pd controller 5. simulation results 5.1 robustness test: model uncertainties 6. conclusion this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 19, no. 2, june, (2023) p. p. 5267 treatment of petroleum refinery wastewater by sono fenton process utilizing the in-situ generated hydrogen peroxide marwa m. jiad* ali h. abbar** *,**department of biochemical engineering/ al-khwarizmi college of engineering/ university of baghdad/ baghdad/ iraq *email: marwa.jeyad2205m@kecbu.uobaghdad.edu.iq **email: ali.abbar@kecbu.uobaghdad.edu.iq (received 30 january 2022; accepted 26 april 2023) https://doi.org/10.22153/kej.2023.04.002 abstract combining ultrasonic irradiation and the fenton process as a sono-fenton process, the chemical oxygen demand (cod) in refinery wastewater was successfully eliminated using response surface methodology (rsm) with central composite design (ccd). the impact of two main influential operational parameters (iron dosage and reaction time) on the cod removal from wastewater generated by an iraqi petroleum refinery facility was explored. removal of 85.81% was attained under the optimal conditions of 21 minutes and 0.289 mm of fe2+ concentration. additionally, the results revealed that the concentration of fe2+ has the highest effect on the cod elimination, followed by reaction time. the high r2 value (96.40%) validated the strong fit of the model equation and the successful adopting rsm in the treatment of wastewaters from petroleum refineries. furthermore, a comparison among sono-fenton, sono-fenton with addition of 𝐻2𝑂2 externally, classical fenton and sonolysis processes showed that the combined process of sono-fenton is better than individual processes and the external addition of 𝐻2𝑂2 . keywords: cod removal, hybrid processes, petroleum refinery wastewater, hybrid processes, sono-fenton; sonolysis, response surface methodology. 1. introduction water is vital to life because it is a necessity for all species. the rapid economic and industrial expansion has facilitated rapid population growth and development [1]. the world is experiencing industry expansion and growth using different industrial methods [2]. continuously producing massive volumes of wastewater at high rates is an environmental issue. these are often discarded without effective management and treatment [3, 4]. from an economic growth standpoint, petroleum refineries and industries are massively important [5]. between 2010 and 2017, opec liquids rose to an average of 1.9 to 1.8 mb/d, with a significant contribution from iraq (millions of barrels daily) [6]. there are more than 15 refineries in iraq, including the refineries in the kurdistan province, and the refining total amounts to more than 1 million barrels per day [6]. how to dispose of this wastewater poses a challenge for petroleum refineries. petroleum industry wastewater comprises several organic and inorganic pollutants, sulfides, and heavy metals [7]. petroleum industry activities, such as oil production, oil refining, transportation, and storage, generate vast quantities of environmental and human health dangerous compounds [6]. various physical, chemical, and biological techniques were utilized to treat wastewater the petroleum sector creates [8]. however, the bulk of these techniques are not mailto:marwa.jeyad2205m@kecbu.uobaghdad.edu.iq mailto:ali.abbar@kecbu.uobaghdad.edu.iq https://doi.org/10.22153/kej.2023.04.002 marwa m. jiad al-khwarizmi engineering journal, vol. 19, no. 2, p.p. 5267 (2023) 53 suggested for separating the various groups of chemicals and are best suited to meet the specific treatment needs of each application [9]. consequently, there is an immediate need to develop effective and environmentally friendly technologies for cleaning contaminated waters from petroleum refineries and decreasing or eliminating contaminants. in the 1980s, advanced oxidation processes (aops) were first found for the treatment of drinking water by glaze et al. (1987) and were later extensively studied for the treatment of various wastewaters [10]. during the aop treatment of wastewater, adequate hydroxyl radicals (oh•) or sulfate radicals (s𝑂4•) are generated to remove refractory organic matters, trace organic contaminants, or certain inorganic pollutants or to increase wastewater biodegradability as a pre-treatment prior to a subsequent biological treatment [11, 12]. multiple types of aops rely on the in-situ formation of oh• radicals via chemical, photo-chemical, sonochemical, or electro-chemical reactions. ultrasound is a superior method of aops, in which water molecules break up and release oh• due to high-frequency acoustic cavitation. after the generation of oh•, the hydroxyl radicals attack the organic pollutant to degrade it (eq.1 and eq.2) [13]. over the last few years, ultrasound has been widely used to remove/degrade organic pollutants from water/wastewater [13]. h2o+ ))) → oh • + h • … (1) organic pollutant + oh • → co2 + h2o …(2) where:))) denotes to the ultrasound waves. sono-lysis creates acoustic cavitation, which involves producing and developing high-energy microbubbles when subjected to periodic pressure. when these bubbles rupture, an increase in temperature (5000 k) and pressure (500 bar) accelerates the dissociation of hazardous chemicals [14]. however, water sono-lysis has several drawbacks, including insufficient oh• production, which results in a lower degradation efficiency of organic pollutants [15]. consequently, several studies have been conducted to combine sonolysis with other aops to improve the overall efficacy of organic pollutant degradation [15-18]. the fenton method, which uses a mixture of soluble iron (ii) salt and hydrogen peroxide (fenton's reagent) to degrade and eliminate refractory organic contaminants, is the oldest and most common chemical aop (eq. 3) [19]. fe2+ + h2o2 → fe3+ + oh− + oh • …(3) the fenton method is favoured among aops because it is user-friendly, has a short reaction time, and runs at room temperature and pressure, making it more cost-effective. in addition, it had other disadvantages, including a narrow ph range and an excessive amount of iron sludge [20]. to overcome classical fenton's limitations, many researchers combine the fenton process with other aops, such as sono-lysis [21, 22]. it is generally known that ultrasonic irradiation of water produces hydrogen peroxide (eq. (1) and eq. (4)) [23, 24, 25]. however, only a few researchers depend on the amount of h2o2 produced by the sonication of water because it is minimal [26]. 2 oh • → h2o2 ...(4) it is worth noting that all local works done in sono-fenton, were done by adding h2o2 externally, and only a few global works were done depending on the in-situ sono-generated h2o2. this study focuses on the combined application of ultrasound and the fenton process for treating natural petroleum refinery wastewater from the al-diwaniya refinery plant located in iraq. the effect of two crucial operating parameters (fe dosage and reaction time) on the chemical oxygen demand (cod) removal rate was investigated by adopting response surface methodology (rsm). 2. materials and methods 2.1 properties of actual refinery wastewater in this investigation, the chosen pollutant was resistant organic cod from the iraqi aldiewanya refinery. prior to the biological treatment stage, 15l of effluents were been obtained from the storage tank and refrigerated at 4⁰c until use. table 1 displays the sample properties submitted by the refinery administration before treatment and after treatment. marwa m. jiad al-khwarizmi engineering journal, vol. 19, no. 2, p.p. 5267 (2023) 54 table. 1. properties of refinery plant wastewater characteristic initial final unit ph 6.6 7.3 temperature 25 22 ºc tds 5566 4898 ppm phenol 18.5 0.05 ppm cod 550 102 ppm bod 180 20 ppm oil 25.2 11.6 mg/l turbidity 33 7.29 ntu po4 30.12 0.8 ppm cl900 450 ppm 2.2 chemicals ferrous sulfate (fes𝑂4.7h2o; 99% pure) and hydrogen peroxide (h2o2,35%) were used as fenton’s reagents and the ph of solution was adjusted using sulfuric acid (1m) and sodium hydroxide (1m). potassium permanganate (kmno4) employed in a titration to estimate the concentration of h2o2 produced in situ. all substances were diluted with deionized water to reach the desired concentrations and the used chemicals were purchased from sigma-aldrich co. (japan). 2.3 sono-fenton system and procedure ultrasonic bath from (isolab laborgerger gmbh, germany) was used for ultrasound irradiation. in which constant ultrasonic power was obtained (60 w) and constant frequency (40 khz). before start any experiment, the ultrasonic bath was switch on and setting the temperature on 25 oc for a period of 15min. a 250 ml of wastewater was put in 500 ml conical flask the ph was adjusted to 3 using 1m 𝐻2𝑆𝑂4 , and the suitable amount of ferrous sulfate was added. after that, the conical flask was closed from top by rubber stopper and placed inside the ultrasonic bath. the flask was fixed by a stand and the ultrasonic bath was covered with a plastic black plate to prevent effect of sun lights. the temperature in all experiments was fixed at 25±3 oc by the ultrasonic bath controller. figure 1 shows the fenton-sonication system. fig. 1. fenton-sonication system. 2.4 analytical method 2.4.1 chemical oxygen demand (cod) cod is the amount of a particular oxidant that reacts with existing pollutants in a sample under controlled conditions. the concentration of chemical oxygen demand (cod) in the effluent was used to quantify the amount of organic compounds in the polluted stream. 2 ml of treated wastewater was digested with 𝐾2𝐶𝑟2𝑂7 as an oxidizing agent for 2 hours at 150 °c in a thermal reactor (lovibond, rd125) to ascertain the cod value. the cod concentration was measured using a spectrophotometer, after bringing the digested sample to ambient temperature, the ph of an electrolyte was determined using a digital ph meter (isolab laborgerger gmbh, germany). the effectiveness of cod removal was determined using (equation 5) [27]: re% = codi−codf codi × 100 ...(5( re% is the removal efficacy, codi is the initial cod (mg/l), and codf is the final cod (mg/l). energy consumption was calculated by (eq. 6) [28]: marwa m. jiad al-khwarizmi engineering journal, vol. 19, no. 2, p.p. 5267 (2023) 55 𝐸 𝐶 = 𝑃𝑒𝑙×𝑡×1000 𝑉60log ( 𝐶𝑂𝐷𝑖 𝐶𝑂𝐷𝑓 ) ...(6) ec is the energy consumption (kwh/m3), 𝑃𝑒𝑙 denotes ultrasound power rates in (kw), t denotes time in (min), and v is the solution volume in (l). 2.4.2 the concentration of 𝐇𝟐𝐎𝟐 generated in-situ by sonication using deionized water, experiments were done in the absence of the pollutant of interest to determine the amount of 𝐻2𝑂2 generated in-situ by sonication. a conical vessel containing 250 ml of phadjusted deionized water was immersed in an ultrasonic bath for 45 minutes. throughout the experiment, samples were taken every fifteen minutes and analyzed using a titration with an aqueous potassium permanganate solution until a subtle pink shade was obtained. the chemical interaction is represented by the equation (eq. 7) [29]: 2mno4 − + 5h2o2 + 6h+ → mn2+ + 5o2 + 8h2o …(7) the h202 concentration was calculated using (eq. 8) [29]: [𝐻2𝑂2] (mg/lit) = 5 2 × 𝑁𝑘𝑚𝑛𝑜4×𝑉𝑘𝑚𝑛𝑜4 𝑉𝐻2𝑂2 × 34 × 1000 … (8) where 𝑁𝑘𝑚𝑛𝑜4 is the molar concentration of 𝑘𝑚𝑛𝑜4 solution (mol/l) and 𝑉𝑘𝑚𝑛𝑜4 and 𝑉𝐻2𝑂2 are the volumes of 𝑘𝑚𝑛𝑜4 and the sample, respectively. 2.5 experimental design the central composite design (ccd) is the most prevalent design in the response surface methodology (rsm) method. the ccd is a fractional factorial design with five levels that is most commonly used to create second-order response surface models. this design consists of three types of points: cube points obtained from a factorial design, axial points, and the center point. n can be determined using the formula n = k2 +2k + n, where k is the number of parameters and n is a number of repetitions [30]. the selected parameters in the current study were the 𝐹𝑒2+ dosage (x1), reaction time (x2) as the factors and cod removal rate (re%) value as the response. the process component scales have been identified as high (+1), median (0), and low (-1). table 2 depicts the selected values for the process variables. as shown in table 3, the minitab-17 software was used to design the array of experiments for this investigation based on ccd. table 2, factors of the process in the refinery plant (coded and real levels). process factors range in ccd coded levels -α low (-1) middle (0) high (+1) +α 𝐹𝑒2+ dosage mm, (x1) 0.0586 0.1 0.2 0.3 0.3414 reaction time min, (x2) 5.8579 10 20 30 34.142 table 3, ccd design experimental array run order blocks coded values real values x1 x2 𝑭𝒆𝟐+ dosage (mm),x1 reaction time (min),x2 1 1 +1 -1 0.3000 10.000 2 1 0 0 0.2000 20.000 3 1 0 0 0.2000 20.000 4 1 0 +α 0.2000 34.142 5 1 +1 +1 0.3000 30.000 6 1 -1 -1 0.1000 10.000 7 1 0 0 0.2000 20.000 8 1 +α 0 0.3414 20.000 9 1 0 -α 0.2000 5.8579 10 1 -1 +1 0.1000 30.000 11 1 -α 0 0.0586 20.000 12 1 0 0 0.2000 20.000 13 1 0 0 0.2000 20.000 marwa m. jiad al-khwarizmi engineering journal, vol. 19, no. 2, p.p. 5267 (2023) 56 response surface model or methodology describes the empirical model expressed as y = f(x1 + x2 +... + xk). the first or second order polynomial models are utilized to develop a suitable approximation for f and are represented below. regarding the 1st order model (eq. 9): y = β° + ∑ βjxj + εk j=1 … (9) and for the 2nd order model (eq. 10): y = β° + ∑ βjxj + ∑ βjjxj 2 +k j=1 k j=1 ∑ ∑ βjixjxi + εi k i=2 k−1 j=1 …(10) y is the predicted response, β° is the constant, x1 , x2 , x3 , x4 and x5 are the operating variables, j, ji (j = 1, 2,..., k; i = 1, 2,..., k) and jj represent the regression coefficients of linear, interaction, and quadratic terms, respectively, and ε is the error. typically, the quadratic model is suitable for rsm in the majority of instances. therefore, models of the first or second order are sometimes refers to a regression models. in addition, fitting an acceptable response surface model involves statistical concepts, regression analysis methodologies, and optimization criteria [31]. 3. results and discussion 3.1 preliminary experiments for determination of in-situ generated 𝐇𝟐𝐎𝟐 by sonication ultrasonic irradiation of an aqueous solution generates oh• radicals and h radicals by cavitation (eq. 1). the hydroxyl radical has a high oxidation potential and can directly oxidize organic substrates, leading to their decomposition or mineralization (eq. 2) [32-33-34]. nevertheless, hydroxyl radicals have a very limited lifetime and tend to bind to generate h2o2 (eq. 4) [35, 36]. the production of hydrogen peroxide by ultrasonic irradiation at different time intervals and at fixed intensity and ph value of 3 is shown in figure 2. it can be seen from fig. 2 that the concentration of h2o2 is increased linearly with time. this result is predicted since many previous studies has demonstrated that, during sonication at constant intensity, the rate of hydroxyl radical formation may be considered to be constant, with hydrogen peroxide being a main result of sonication (eq. 4 and eq. 11) accumulating linearly in solution and serving as an oh• scavenger under ultrasonic irradiation [37-39]. consequently, at the current study the rate of h2o2 generation is considered constant since ultrasonic intensity is also constant. 2 ooh → h2o2 + o2 … (11) fig. 2. h2o2 in-situ generation by sonication. 3.2 statistical analysis of the sono-fenton results thirteen runs were performed in accordance with the ccd in order to find out and optimize the effects of process operating parameters on cod removal efficacy (re%). table 4 shows the number of runs, the experimental circumstances, the actual and estimated cod removal efficiency re%. marwa m. jiad al-khwarizmi engineering journal, vol. 19, no. 2, p.p. 5267 (2023) 57 table 4, ccd results run order blocks fe dosage(mm) time (min) re%actual re% predicted 1 1 0.3000 10.000 80.78 81.9626 2 1 0.2000 20.000 86.89 85.4780 3 1 0.2000 20.000 85.00 85.4780 4 1 0.2000 34.142 75.98 75.0894 5 1 0.3000 30.000 82.31 84.4162 6 1 0.1000 10.000 70.00 68.3688 7 1 0.2000 20.000 83.00 85.4780 8 1 0.3414 20.000 90.00 87.7728 9 1 0.2000 5.8579 73.00 73.4156 10 1 0.1000 30.000 68.99 68.2824 11 1 0.0586 20.000 65.00 66.7522 12 1 0.2000 20.000 88.00 85.4780 13 1 0.2000 20.000 84.50 85.4780 results in table 4 showed that re% is ranged between 65-90%. a comparison between run 8 and run 11 at the mid value of time (20 min) displays that fe2+ dosage has the higher effect on cod removal with a maximum difference of 25% while at the mid value of 𝐹𝑒2+ dosage (0.2mm) effect of time is the lower with a maximum deference of 3% (runs 4 and 9). however, the real effect of each variable could be observed by anova analysis. the quadratic model regression was obtained by minitab-17 software in terms of actual values (eq. 12): re% =33.09 + 225.9 x1 + 2.177 x2 410.8 𝑋1 2 0.05613 𝑋2 2+ 0.64 x1*x2 …(12) where x1*x2 describe the interaction influence of model parameters and the double influences of model parameters (x1)2 and (x2)2 were utilized to determine the magnitude of their impact. the negative and positive coefficients in the model represent the negative and positive influence of experimental factors on cod elimination, respectively. as stated in equation (12), the maximum coefficient belonged to (x1*x1) factor, implying that the double effect of 𝐹𝑒2+ dosage has the highest effect on the removal of cod during sono-fenton process when compared to the other independent variables. in contrast, a low coefficient showed that double effect of reaction time (x2*x2) had the minimal effect on the response. by graphing the anticipated versus actual data and the normal probability plot of the standardized residuals, the attractiveness and sufficiency of the model were also confirmed in figure 3. it is evident from figure 3 that there is a strong correlation between the experimental and estimated values, showing that the model was well-fitted and had a good ability to predict the cod removal rate re%. no scattering with no definite pattern was observed, respecting the residuals revealing the significance of the model. this may be interpreted as below [40]: a) no outliers exist in the data with respect to normal probability plot. this states that data are normally distributed and the re% is affected by 𝐹𝑒2+ dosage and time. b) a non-linear relationship was observed with respect to the plot of residuals versus fitted values plot confirming the variance is constant. c) no skewing nor outliers were existed in histogram. d) an organized effects were observed in the data plot on residuals versus order due to time or data collection order. marwa m. jiad al-khwarizmi engineering journal, vol. 19, no. 2, p.p. 5267 (2023) 58 fig. 3. residual plots of cod removal rate by sono-fenton. in addition, the model's sufficiency and significance were evaluated using analysis of variance (anova), and the results are shown in table 6. the model 𝑅2 and 𝑅2𝑎𝑑𝑗𝑢𝑠𝑡𝑒𝑑 values of 96.40% and 92.20%, respectively was relatively high, which indicates that the model obtained was able to give a convincingly good estimate of response in the studied range [41]. furthermore, anova table reveals that the present of contribution of the model was 95.68% and the linear term contr.% is 57.03 in which 𝐹𝑒2+ dosage (x1) contr.% of 56.67 which represents the majority of the linear term with very week contribution of reaction time (x2) 0.36%.the week contribution of time could be results from nonlinear its behavior with re%. the double (square) effect term contributes in the model was 38.45% while the interaction term was 0.21% only which is very insignificant. according to the anova table, the model was extremely significant as the fisher f test (f value) was determined to be 31.02 with a very low probability value (p value 0.0001), indicating that there was only a 0.01% chance that such a model could have been caused by noise [42]. table 6. analysis of variance results source df seq ss contr. % adj ss adj ms f-value p-value model 5 746.075 95.68 746.075 149.215 31.02 0.000 linear 2 444.669 57.03 444.669 222.334 46.22 0.000 x1 1 441.867 56.67 441.867 441.867 91.86 0.000 x2 1 2.808 0.36 2.802 2.802 0.58 0.470 square 2 299.793 38.45 299.793 149.896 31.16 0.000 x1*x1 1 80.642 10.34 117.382 117.382 24.40 0.002 x2*x2 1 219.151 28.11 219.151 219.151 45.56 0.000 2-way interaction 1 1.613 0.21 1.613 1.613 0.34 0.581 x1*x2 1 1.613 0.21 1.613 1.613 0.34 0.581 error 7 33.672 4.32 33.672 4.810 lack of fit 3 17.993 2.31 17.993 5.998 1.53 0.337 pure error 4 15.680 2.01 15.680 3.920 total 12 779.747 100.00 model summary r2 r2(adj.) r2(pred.) 96.40% 92.20% 80.45% marwa m. jiad al-khwarizmi engineering journal, vol. 19, no. 2, p.p. 5267 (2023) 59 3.3 effect of operating factors on the sonofenton process the surface plot combined with the contour plot was used to investigate the effect of fe dosage and time on the cod removal efficiency, as shown in figure 4 a, b. it was clear that increasing fe dosage results in increasing re% to an optimum fe dosage beyond which no further increase of re% could occur. this behaviour occurs at any time. this can be interpreted as increasing the fe2+ dosage results in increase the cod removal rate due to fe2+ reaction with the in-situ generated hydrogen peroxide according to (eq. 3) [43]. pang and his coauthors [44] stated that increasing fe2+ dosage would also increase the sono-fenton process’s efficiency. nevertheless, with increasing the fe2+ dosage more than the optimum value, self-quenching of •oh to produce fe3+ through (eq. 13) could occur fe2+ + oh • → fe3+ +oh− … (13) then, the resulting fe3+ can further react with h2o2 to form a complex intermediate (fe (ho2)2+) (eq. 14). although (fe (ho2)2+) can be spontaneously decomposed to fe2+ and •ooh, the decomposition rate was much lower. the decomposition rate of (fe (ho2)2+) can be greatly enhanced under ultrasonic irradiation (eq. 15). a cycle mechanism is established once the isolated fe2+ further reacts with h2o2 to produce •oh (eq. 3) [45, 46]. fe3+ + h2o2 → fe − o2h2+ + h+ … (14) fe − o2h2++ ))) → fe2+ + ooh • …(15) several studies had investigated the effect of iron dosage on the sono-fenton process, and the majority of researchers have concluded that the degradation of pollutants by the sono-fenton process increased significantly with the addition of fe2+ [47-50]. on the whole, the addition of fe2+ is generally beneficial for the acceleration of organic compound degradation; however, an excessive dosage of fe2+ will decrease treatment efficiency due to the reduction of oh• caused by the addition of excessive fe2+ (eq. 13) [50-52]. consequently, higher iron dosages are only advantageous under specific conditions. according to previous studies, reaction time is one of the most crucial parameters affecting hybrid wastewater treatment systems [53, 54]. based on figure 4-a, the re% increases with increasing time up to 20 min then starts to decrease. according to data concerning the effect of reaction time, as the time climbed from 20 to 34.14 min at constant fe2+ dosage 0.2 mm, the rate of removal decreased by 9.02%. this is probably because the in-situ generated hydrogen peroxide by sonication was partially consumed [55]. this behavior was happen at any value of fe dosage. in the majority of previous literature reviews, it was found that the cod removal rate increased as the reaction time increased. this behaviour is expected due to the increased production of hydroxyl radicals oh• during sonication [31, 14, 56-58]. in contrast, in the current study, increasing the reaction time beyond 20 minutes will decrease the cod removal rate, which is an unpredicted result consistent with a small number of previous findings [59-61]. yosofi and mousavi [62] attributed that the decrease of rb5 removal rate happened when the concentration of h2o2 elevated to 400 mg/l due to the consumption of oh• radicals by extra hydrogen peroxide at high concentration instead of reacting with rb5 eqs. (16, 17, 18) [62]. oh • + h2o2 → ho2 • + h2o ...(16) ho2 • + oh • → h2o + o2 … (17) h • + h2o2 → ho2 • + h2 .. (18) however, the rate of h2o2 generation at the current study was considered constant, authors suggests that the oh• radicals instead of attacking the organic pollutant, it will continue producing h2o2 overtime and hence accumulating it in the solution which results in consuming oh• (eq. 16, 17, 18) in the same behavior of [62] when authors increased the concentration of h2o2. in addition, the accumulated hydrogen peroxide may function as a hydroxyl radical scavenger, resulting in the production of hydro-peroxy radicals that are less reactive than hydroxyl radicals (eq. 19) [61]. h2o2 + oh • → ho2 • + h2o … (19) marwa m. jiad al-khwarizmi engineering journal, vol. 19, no. 2, p.p. 5267 (2023) 60 (a) (b) fig. 4. the interaction effect of fe dosage and time on the cod removal. a)surface plot, b) contour plot. the contour plot is significant to detect the reign of optimum values. as shown in figure 4-b, the higher removal rate with re% higher than 85% could be attained only at fe dosage greater than 0.2 mm and time in the range (15-25min), hence the optimization results should be lied with this scope. 3.4 optimization the primary objective of ccd-based rsm was to identify the ideal operating parameters for maximizing the percent of cod removal efficiency in the treatment of petroleum refinery wastewater by the hybrid process (sono-fenton). minitab-17 software was used to maximize the cod re%, taking into account the variety of examined parameters and their responses as shown in tables 2 and 5, respectively. within these constraints and parameters, the optimization technique was carried out, and the results are displayed in table 7 and figure 5. for confirmation, an experiment was conducted utilizing the improved parameters. besides, for comparing the efficiency of combining ultrasound irradiation with fenton reaction, three more experiments were done (sonolysis, classical fenton, and sono-fenton with addition of h2o2 externally). table 8 provides the results. after approximately 21 minutes of the sono-fenton process, the cod removal efficiency at ph=3 was 85.81% (in the range of the optimal value determined by optimization analysis with a df of 1) (table 6). consequently, employing ccd in conjunction with df is effective and efficient for maximizing cod elimination using sono-fenton hybrid advanced oxidation method. based on the present method, the final cod concentration was (65ppm) which is lower than the value of the effluent discharge from the 10 02 60 70 80 1.0 03 .0 0.2 .0 3 80 09 %er )mm( egasod ef )nim( emit time (min) f e d o sa g e ( m m ) 3025201510 0.30 0.25 0.20 0.15 0.10 > – – – – – < 60 60 65 65 70 70 75 75 80 80 85 85 re% marwa m. jiad al-khwarizmi engineering journal, vol. 19, no. 2, p.p. 5267 (2023) 61 biological unit (102 ppm) used in the aldiewanya refinery plant and is in agreements with the standard level for discharging of wastewaters globally. external addition of h2o2 to sono-fenton was found to decrease the cod removal rate to be 57.68% and a dark yellow color of the solution after treatment was observed. this could be due to the reaction between excessive h2o2 and oh• according to (eq. 19), which results in the creation of ho2 •, which has insignificant oxidative strength in comparison to hydroxyl free radicals [63, 64]. at greater concentrations of hydrogen peroxide, 𝐻2𝑂2 served as an interfering agent and reacted with hydroxyl radicals oh• in the aqueous medium, thereby limiting their attack on contaminant molecules [64]. in addition, sonolysis alone and classical fenton process give removal efficiency of 64.84% and 56% ,respectively which is also lower than the hybrid sono-fenton process removal. this is because of the increased number of hydroxyl radicals generated by sono-fenton, therefore, the rate of breakdown and oxidation of organic matter will also increase. since the number of radicals derived from 𝐻2𝑂2 in the hybrid system is greater than in an isolated sonication system, the rate of oxidation will be greater in the hybrid system [65]. table 7. response optimization: re% response target lower upper weight importance re (%) max 65 90 1 1 parameters fe2+ (mm) time (min) fit se fit 95% ci 95% pi 0.29 21 88.90 1.06 86.38-91.41 83.14-94.66 fig. 5. optimization plot table 8. confirmative run with comparison with related processes run case fe2+ (mm) time (min) h2o2 cod (ppm) re% initial final 1 sono-fenton 0.29 21 458 65 85.81 2 sono-fenton with addition of 𝐻2𝑂2 externally 0.29 21 2.9mm 458 193 57.86 3 sonolysis only 21 458 161 64.84 4 classical fenton process 0.29 21 458 199 56.55 marwa m. jiad al-khwarizmi engineering journal, vol. 19, no. 2, p.p. 5267 (2023) 62 3.5 comparison with previous works the results of the current study were compared to prior research in the same field in table 9. it demonstrates that the current results are favorable in terms of the high removal rate in a brief amount of time, approximately 20 minutes, the lack of energy consumed, and the low cost, which encourages the adoption of the current method for treating polluted water from sources other than oil refineries, such as textile and cosmetics factories. table 9. comparison with previous works reference optimum conditions process [22] re%=58.2 =30 mg/l, 2+200mg/l, fel pheno =800mg/l, 2o2h ph=3,time=60min temperature =30º c degradation of phenol in aqueous solution by fenton, sono‐fenton and sono‐photo‐fenton methods [66] for us/ 2o2/h2+fe re%=40 ec=216kwh 3m/ =30mm2+fe ph=7,time=180 min temperature =30º c ozone (o3) and sono (us) based advanced oxidation processes for the removal of color, cod for landfill leachate [67] re%=84.25 =102+/fe2o2h ph=3, time=10 min treatment of petroleum effluents using the combined ultrasound and fenton oxidation process [25] re%=95.3 =0.2mm2+fe ph=3,time=10 min temperature =30c the production of sono-fenton system by trace ferrous ion addition in sono-degradation dimethoate present study re%=85.81 ec=90.57k 3wh/m =0.289 mm2+fe ph=3,time=21 min temperature =30c petroleum refinery wastewater /sonofenton 4. conclusion in this research, combining of ultrasound irradiation and fenton as a hybrid process was investigated to treat real petroleum refinery wastewater. the optimum operation variables were found by response surface methodology (rsm) with central composite design (ccd). a maximum concentration of h2o2 that generated in-situ by sonication was found to be 8.5 mg/l at 45min and its rate was constant throughout all experiments. the optimal re% for sono-fenton process was 85.81% obtained at 21 minutes and fe2+ dosage of 0.289. analysis of variance (anova) showed that the model r2 is 96.40% and the fe2+ dosage is the main factor that greatly affects the treatment process. the results revealed that the efficiency of the individual classical fenton process and sonolysis process were low. in contrast, when fenton is combined with sonication, the removal efficiency is considerably enhanced. adding external h2o2 has an adverse 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(2018). efficiency of sononano-catalytic process of magnesium oxide nano particle in removal of penicillin g from aqueous solution. desalination and water treatment, 106, 330-335. [64] homem, v., & santos, l. (2011). degradation and removal methods of antibiotics from aqueous matrices–a review. journal of environmental management, 92(10), 2304-2347. [65] rahdar, s., igwegbe, c. a., ghasemi, m., & ahmadi, s. (2019). degradation of aniline by the combined process of ultrasound and hydrogen peroxide (us/h2o2). methodsx, 6, 492-499. [66] asaithambi, p., sajjadi, b., aziz, a. r. a., & daud, w. m. a. b. w. (2017). ozone (o3) and sono (us) based advanced oxidation processes for the removal of color, cod and determination of electrical energy from landfill leachate. separation and purification technology, 172, 442-449. [67] sivagami, k., anand, d., divyapriya, g., & nambi, i. (2019). treatment of petroleum oil spill sludge using the combined ultrasound and fenton oxidation process. ultrasonics sonochemistry, 51, 340-349. (2023) 52-67، صفحة 2، العدد19مجلة الخوارزمي الهندسية المجلد مروة محسن جياد 67 ثمارمعالجة المياه العادمة الخارجة من مصافي النفط بأعتماد عملية السونوفنتون وبأست بيروكسيد الهيدروجين المتولد آنيًا من الموجات الفوق الصوتية **علي حسين عبار *مروة محسن جياد جامعة بغداد كلية الهندسة الخوارزمي/ قسم الهندسة الكيميائية االحيائية/**,* marwa.jeyad2205m@kecbu.uobaghdad.edu.iqالبريد األلكتروني: * ali.abbar@kecbu.uobaghdad.edu.iq:البريد األلكتروني ** الخالصة طريقة جديدة لمعالجة المياه العادمة الخارجة من المصافي النفطية من خالل الجمع بين الموجات فوق الصوتية وعملية الفنتون كعملية الدراسةتقدم هذه تمت دراسة اثنين من العوامل المؤثرة الرئيسية على العملية . (%re)كدالة هدف (cod) لألوكسجينتم اختيار ازالة الطلب الكيميائي . فنتون-سونو (ccd) مع اعتماد التصميم المركب المركزي respone surface methodology (rsm)البرنامج االحصائي منهجية سطح االستجابة باستخدام central composite design . تم الحصول على أعلى نسبة ازالة reملي موالر من 0.289دقيقة و 21ظروف المثالية لمدة في ال ٪85.81 ٪ وهي 2r أثبتت قيمة . ، يليه وقت التفاعل cod له أعلى تأثير على التخلص من +fe2 باإلضافة إلى ذلك ، أوضحت النتائج أن تركيز +fe2 الحديد عالوة على ذلك ، .في معالجة المياه العادمة من مصافي البترول rsm صحة التوافق القوي لمعادلة النموذج واالعتماد الناجح لـ( ٪96.40)المرتفعة فنتون التي تم اجرائها باالعتماد على الكمية المتولدة داخليا من بيروكسيد الهيدروجين عن طريق الموجات فوق الصوتية -أظهرت مقارنة بين عملية سونو عملية sonolysis الكالسيكية و الفنتون الخارجية لبيروكسيد الهيدروجين وايضا عمليةفنتون أخرى تم اجراءها عن طريق االضافة -وبين عملية سونو التي تم اجراءها بدون اضافة فنتون-هي العملية المشتركة السونو لإلزالةأفضل عملية أن الصوتنة االعتيادية بدون اضافة الحديد وبيروكسيد الهيدروجين .بيروكسيد الهيدروجين خارجيا وان هذه العملية افضل من العمليات الفردية الكالسيكية كالفنتون فقط او الصوتنة فقط mailto:marwa.jeyad2205m@kecbu.uobaghdad.edu.iq mailto:ali.abbar@kecbu.uobaghdad.edu.iq microsoft word ??? ???? ????2033 al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 17, no. 1, march, (2021) p. p. 2033 influence of aging heat treatment on pitting corrosion resistance of martensitic stainless steel abdullah dhayea assi middle technical university/ institute of technology baghdad/ baghdad/ iraq email: drabdullah_dhayea@mtu.edu.iq (received 19 june 2019; accepted 9 december 2020) https://doi.org/10.22153/kej.2021.12.003 abstract this research aim to study the influence of aging heat treatment on the pitting corrosion resistance of martensitic stainless steel (mss), where a number of martensitic stainless steel specimens were subjected to solution treatment at 1100 oc for one hour followed by water quenching then aging in the temperatures range (500-750) oc for different holding times (1, 5, 10, 15 & 20) hr. accelerated chemical corrosion test and immersion chemical corrosion test were performed on samples after heat treatment. the results of the research showed that the pitting corrosion resistance is significantly affected by the aging temperature. where samples that aged at 500 °c have the highest rate of corrosion due to an increase in the ratio of the delta ferrite (δ-ferrite) and very soft precipitates from other phases of heterogeneous form in the basic martensitic phase; which leads to increase corrosion rate. from the other side, the aged samples in the temperature range (550–650) °c have the smaller rate of corrosion, this is due to the high volumetric ratio of remaining austenite. the aged samples at temperatures above 650 °c shows a medium corrosion rate. it was also found that the type of pits results from both the chemical corrosion tests and their shape were not related to the ferrite type and the carbides present in the microstructure. keywords: martensitic, stainless steel, thermal aging, pitting corrosion resistance. 1. introduction the need to use steels at medium operating temperatures and high ratios of tensile strength to the weight led to develop one type of stainless steel which have corrosion resistance and hardened by precipitation, the martensitic type. these types of stainless steel have proven their efficiency in applications with chemical corrosion resistance, such as oil, marine and nuclear applications, as they are exposed to corrosive media. the chemical corrosion resistivity of martensitic stainless steel which has corrosion resistance and hardened by precipitation is better than other martensitic types and can be compared with austenitic stainless steels in most media. therefore, it widely used in military and nonmilitary equipment, and completely preferred compared with immersed and refractory martensitic steels [1]. electrochemical studies of chemical corrosion of stainless steel have shown that the chemical composition and microstructure of these steels are important factors in determining chemical corrosion behavior. as well as, the chromium content of stainless steel is important in order to obtain and maintain good chemical corrosion resistance under certain operating conditions. if the chromium content is low at the granule boundary, the steel will be vulnerable to attack and corrosion among the granules even if there is high chromium content in the basic freezing solution. on the other side, if chromiumrich carbides are concentrated on the grain boundaries, there will be a shortage of chromium in the vicinity of the boundary and the carbides abdullah dhayea assi al-khwarizmi engineering journal, vol. 17, no. 1, p.p. 2033 (2021) 21 will begin to settle there. this will corrupt the chemical corrosion resistance in these areas and will result in granule local corrosion [2]. the study of the chemical wear behavior of stainless steel that can be quickly deposited and frozen shows that it is produced in the form of chrome-rich and molybdenum-rich carbide on the boundary of grains, which can be the cause of the high susceptibility of these alloys to pitting corrosion [3]. the heat treatment of stainless steels helps to produce changes in the physical state, mechanical properties, residual stress levels, and in restoring maximum chemical corrosion resistance when these properties are adversely affected by various manufacturing or heating processes. an acceptable combination of resistance to chemical corrosion with optimum mechanical properties can be obtained by appropriate choice of heat treatment. in general, any improvement in the mechanical properties of steels by rapid cooling and revision will inevitably associated with increased chemical corrosion [4]. the general corrosion behavior of sintered 174 ph stainless steel processed under different processing conditions in dilute sulfuric acid solution at 25 °c was studied by open-circuit potential measurement and potentiodynamic polarization technique. the results showed that the precipitation-hardening treatment could significantly improve the corrosion resistance of the sintered 17-4 ph stainless steel in studied environment. it can be concluded that the highest corrosion resistance in 0.5 m h2so4 solution exhibits 17-4 ph after solution treatment at 1040 °c followed by aging at 480 °c [5]. pitting corrosion properties were investigated in 0.6m nacl electrolyte with sulfate additions by potentiodynamic polarization (pp). hardness, tensile and yield strength of the uns s46500 steel after lower aging temperature, 510ºc (h950), are higher than the ones found in the 538ºc (h1000) aged steel. this result is explained by microstructure, x-ray diffraction and thermocalc analysis, which indicated the presence of austenite, chi phase and probably ni3ti precipitates finely and uniform distributed throughout the martensite matrix [6]. the aim of this research is to study the influences of aging heat treatment and the resultant phases on the pitting corrosion resistance of martensitic stainless steel through accelerated chemical corrosion as well as immersion chemical corrosion tests that have to be performed on samples after aging heat treatment. this is due to the necessary need for this type of stainless steel in various applications. 2. experimental work 2.1. materials the materials used in this research are martensitic stainless steel sheets hardened by precipitation hardening that was pre-exposed by the manufacturer to the normalizing process at a temperature of 924 °c, then cooled in the air and exposed to aging process at 600 °c. it finally cooled in the air to room temperature. the chemical analysis of the used steel was obtained by the spectroscopy device (model spector maxx). table (1) shows the chemical composition of this steel and steel grade 420ss [7] . table 1, the chemical composition of the used stainless-steel. 2.2. heat treatment the previous sheets were cut into 32 samples with dimensions of (10 × 5 mm) for each sample, and then subjected to the following heat treatments: 1solution treatment at 1100 °c for one hour, then immersed in water. 2aging at temperatures 500, 550, 600, 650, 700, and 750 °c for five hours, and then cooled by air 3aging at two temperatures 500 and 650 °c during different times 1, 5, 10, 15, and 20 hours. the samples were heated using two electric furnaces as shown in figure (1a), the first for the dissolution treatment and the second for the aging process . element % c cr ni mo si mn s p ti fe standard [7] 0.07 15-17 3-5 0.5-2 0.25-0.5 0.5-1 0.002 0.01-0.04 0.45 bal. measured 0.05 15.5 5.6 0.80 0.3 0.70 0.002 0.02 0.4 bal. abdullah dhayea assi al-khwarizmi engineering journal, vol. 17, no. 1, p.p. 2033 (2021) 22 fig. 1a. two electric furnaces for heat treatment. 2.3. chemical corrosion test (dynamic voltage or acceleration test) chemical corrosion testing or acceleration testing is an effective widely used method in estimating the chemical corrosion in aqueous media by passing a current into the electrode using an inert electrode.  the degree of polarization is determined by measuring the sample voltage, while the rate of electrode reaction is measured from the density of the cell current that it directly transits to a chemical corrosion rate measured in mm/year. the anode and cathode polarization diagrams of electrodes (samples) exposed to a 6% fecl3 solution are plotted and the electrode area is 0.5 cm2. these diagrams are obtained using ps6 device connected with a computer. the voltage range was found in all tests from 200 to +1000 mv, and the scan rate was set to 0.5 mv/s. this test was carried out at room temperature at the ministry of science and technology / department of materials as shown in figure (1b). fig. 1b. the chemical corrosion test. 2.4. pitting chemical corrosion test (immersion test) the pitting chemical corrosion resistance was measured according to astm g48 for pitting test by using a ferric chloride (fecl3) as immersion solution with a concentration of 6% prepared by dissolving 100 g of aqueous ferric chloride (fecl3. 6h2o) in 900 ml distilled water . the test was carried out in the following manner: 1the samples are firstly weighed 2the samples are immersed in the previous solution for 72 hours. 3the samples are removed from the solution and washed with distilled water to remove dissolved oxides that have formed on the surface of the samples, 4the samples are weighed again. 5 the weight loss is calculated by the difference between the two weights. finally, the samples are examined under a microscope at 50 times magnification and the pitting spots formed on the surface of the samples are captured according to the previous specification with changing the immersion solution after each immersion and existing process of samples.the corrosion rate can be calculated by equation (1) [reference]: where: 3650 w cr a d t     …(1) cr: corrosion rate (mm / year) w: weight loss = initial weight final weight in (grams) a: sample exposed surface area (cm2) abdullah dhayea assi al-khwarizmi engineering journal, vol. 17, no. 1, p.p. 2033 (2021) 23 d: tested material density (gm / cm3) t: immersion time (day) 2.5. microstructure test the microstructures of the heat-treated samples that were subjected to chemical corrosion tests have been examined by using an olympos optical microscope. samples were prepared for microscopic examination of sharpening, polishing and smoothing with fry solution for smoothing consisting of (5g from cucl2 copper chloride) + (40 ml from hcl) + (30 ml from methyl alcohol) and 30 ml of water. the phases and microscopic components, such as the martensitic matrix and the delta ferrite phase, were identified using an optical microscope, since the martensitic floor appeared in the form of plates, while the delta type ferrite appeared in small quantities in the form of longitudinal white ribs, and no presence of austenite was found in this sample, as indicated by in figure (2). the volumetric ratios for the austenite were determined using xrd diffraction technique according to the method described in astm e975-95 . fig. 2. the microstructure of soluble treated samples at a temperature of 1100 °c (50x). 3. results 3.1 effect of aging process on austenite volumetric ratios figure (3) shows the effect of aging temperature on the austenite volumetric percentages. it was found that by increasing the aging temperature, the austenite volumetric ratios gradually increase, and the maximum value of the austenite volumetric ratios occurs at a temperature of 650 °c. after that, a gradual decrease was occurred down to temperature of 750 °c. fig. 3. effect of four hours aging temperature on volumetric ratio for austenite. abdullah dhayea assi al-khwarizmi engineering journal, vol. 17, no. 1, p.p. 2033 (2021) 24 the effect of aging time on the austenite volumetric percentages at 500 and 650 ° c aging is shown in figure (4). no significant change in the residual austenite volumetric percentages at 500 °c was noticed. while at aging temperature of 650 °c increases the amount of austenite was significantly increased from 20% to 55%; by increasing the aging time from 1 to 20 hours. fig. 4. effect of aging time on the austenite volumetric percentage at two aging temperatures. 3.2 the effect of aging process on the microstructure the microscopic structure of heat-treated samples at different aging temperatures and times were shown in figures (5 to 11). all microscopic structures consist mainly of low carbon martensitic and variable percentages of ferrite delta type, which sometimes present in the form of longitudinal ribs. the fundamental change in the microscopic structure with increasing aging temperature and time was the decomposition of martensitic associated with the appearance of austenite. the volumetric ratio of the austenite was increased by increasing the aging temperature up to 650 °c. the microstructure of the aging samples at a temperature of 500 °c and a time of 4 hours was shown in figure (5). the form of elongated carrots, martensitic slices and also austenitic elongated granules, which arise between the martensitic slices within the former austenitic granules, leading to the variation of the microscopic structure. figure (6) shows the microscopic image of the aging specimens at 500 °c for one hour. the typical low-carbon slice martensitic structure is shown in the former austenitic granule. the transformation of martensitic to austenite becomes more pronounced by increasing the aging temperature and time. at temperature aging of 550 °c for 5 hours the same microstructure as shown in figure (7) where a high number of longitudinal grounded austenite were pronounced. this decomposition of martensitic becomes more pronounced at temperatures of (550 and 600 °c) as shown in figures (7 and 8) below . in this case the austenite volumetric percentage was about 20% as shown from previous figure (3). after the aging temperature of 600 °c for 5 hours, the microstructure is almost identical to that of the previous 550 °c as shown in figure (8), but the residual austenite volume increases to about 30%. fig. 5. microstructure of aging specimens at temperature 500 ° c and aging time 5 hrs 200 x . abdullah dhayea assi al-khwarizmi engineering journal, vol. 17, no. 1, p.p. 2033 (2021) 25 fig. 6. microstructure of aging samples at 550 oc for 1 hour (200x). fig. 7. microstructure of aging samples at a temperature of 550 oc for 5 hours (100x). fig. 8. microstructure of aging samples at a temperature of 600 °c for 5 hours (200x). the maximum residual austenite value of 32% is shown in the sample treated at 650 ° c for 5 hours as shown in figure (9). the microstructure seems to be as equal axes granules, which can be seen inside these soft needle-shaped microstructures. examination of this structure at high magnification showed that the residual austenite granules are elongated, and their volumetric ratio increased with the aging time from 1 to 20 hours as shown in figure (10). the former austenitic granules are dark in color and others are light in color and larger in size. fig. 9. microstructure of aging samples at 650 oc for 5 hours (200x). fig. 10. microstructure of aging samples at 650 oc for 16 hours (1000x). the microstructure of the aging samples at a temperature of 700 °c for 5 hours is shown in figure (11). in this figure the ribs of ferrite delta type are shown and adjacent to them are often bright white elongated granules and others with almost equal axes. these granules are for the residual austenite which has been converted to non-aging martensitic. abdullah dhayea assi al-khwarizmi engineering journal, vol. 17, no. 1, p.p. 2033 (2021) 26 fig. 11. microstructure of aging samples at 700 oc for 4 hours (500x) 3.3 effect of aging process on chemical corrosion rate (dynamic voltage and immersion tests) figure (12) shows the effect of 5-hours aging temperatures on the chemical corrosion rate (with 6% iron chloride acceleration test) and immersion test, as it appears from this form the following points: 1. the chemical corrosion rate is increasing sharply in the aging temperature range from (500 to 550) °c. 2 the largest value of the rate of chemical corrosion is about 2.5 mm / year; when aging to a temperature of 550 °c. 3. the chemical corrosion rate decreases steeply when aging in a temperature range of (550 to 600) °c 4 the minimum value of the rate of chemical corrosion about 0.2 mm / year that produced at aging range of (550 to 650) °c. 5. the rate of chemical corrosion increases again, gradually, when aging after the previous field. fig. 12. effect of 5-hour aging temperature on chemical corrosion rate due to acceleration test (dynamic voltage test) and immersion test . figure (13) shows the effect of aging time on the chemical corrosion rate; at 550 and 650 ° c aging temperatures, when aging at a temperature equal to 550 °c, the initial phase of chemical corrosion increases from 1 to 5 hours. the maximum value of the chemical corrosion rate was at an aging time of 5 hours, after which the rate of chemical corrosion gradually decreases. when aging at a temperature equal to 650 °c, the chemical corrosion rate gradually increases with the aging time and the increase rate is much faster after aging time of 10 hours. abdullah dhayea assi al-khwarizmi engineering journal, vol. 17, no. 1, p.p. 2033 (2021) 27 fig. 13. effect of aging time on the chemical corrosion rate of aging samples at an aging temperature of (500 and 650) °c from the accelerometer test (dynamic voltage test). 3.4 effect of aging process on voltage figure (14) shows the effect of increasing the aging temperature on the voltage; at an aging time of 5 hours, this figure shows the following :  the voltage decreases gradually by increasing the aging temperature in the range from (500 to 650) °c, and produces the lowest voltage when aging at 650 °c.  the voltage increases significantly by increasing the temperature in the field from (650 to 750) °c. fig. 14. effect of aging temperature for 5 hours on voltage . the effect of aging time on voltage is shown in figure (15) at (500 and 650) °c. an increase in voltage is observed at each aging temperature, starting from an equal aging time to one hour, and the rate of increase is much faster at an aging temperature of 500 °c, and the maximum value of the voltage is produced by aging for 10 hours; this is at all the two temperature ranges of aging. on the other hand, the voltage decreases gradually when the aging time increases above 10 hours and after (15) hours the rate of decrease is slower. the aging sample at a temperature of 500 °c had a higher voltage than the aging sample at a temperature of abdullah dhayea assi al-khwarizmi engineering journal, vol. 17, no. 1, p.p. 2033 (2021) 28 fig. 15. effect of aging time on voltage at two aging temperatures . 3.5 effect of aging process on chemical corrosion rate (immersion test): the changes in the chemical corrosion rate resulting from this test are shown in figure (16). by changing the corrosion time of samples at the aging temperatures of (500 and 650) ° c, the changes in the rate of chemical corrosion by changing the aging time are similar to those resulting from the previous test (the accelerated test), but the values of the chemical corrosion rate are higher in this case. the results can be studied and divided into two types: 1. the chemical corrosion rate of aging samples increases at 500 °c, in the first stage of the scheme from the time of aging 1 to 5 hours and the maximum value of the chemical corrosion rate occurs when aging for 5 hours, after which time the chemical corrosion rate gradually decreases with increased aging time. 2. the rate of chemical corrosion gradually increases with the aging time of the aging samples at 650 °c, and the rate of increase is faster after aging time of 15 hours . fig. 16. effect of aging time on chemical corrosion rate of aging samples at 500 and 650 °c aging temperatures. 3.6. click forms in aging samples at different time temperatures figures (17) to (19) show microscopic images of aging samples at different aging temperatures and times tested by accelerated testing. from these images it can be seen that there is a deep and large mortise on the surface of the aging sample at a temperature of 550 ° c as shown in figure (17b), which corresponds to the high chemical corrosion rate previously measured. when the sample is released at a temperature of 600 °c, the clicking is smaller and deeper than the rest of the sample as shown in figure (17c), while the size of the tap formed on the surface of the aging sample at 750 °c is larger than that formed on the sample surface. the aging is 550 abdullah dhayea assi al-khwarizmi engineering journal, vol. 17, no. 1, p.p. 2033 (2021) 29 °c, but remains smaller than the aging sample at 500 °c, as shown in figure (17f). an increase in the aging time with the aging temperature constant at 500 °c indicates that there is a clear decrease in the flick size after being tested by acceleration method as shown in figure (18), and the smallest flick size after aging is formed within a period of 20 hours as evident from figure (18e). conversely, by increasing the aging time at 650 ° c there is a noticeable increase in the size of the flick as shown in figure (18), and the larger flick size is formed in the sample that was released at 20 hours as shown in figure (18k). fig. 17. microscopic images of aging samples for 4 hours at different aging temperatures. (a, g) 500, (b, h) 550, (c, i) 600, (d, j) 650, (e, k) 700, (f, l) 750 °c, where (a, b, c, d, e, f, acceleration test) and (g, h, i, j, k, l, immersion test). fig. 18. microscopic images of aging samples during different aging times;(a) 1hr, (b) 5hr, (c) 10hr, (d) 15hr, (e) 20hr: acceleration test where (a, b, c, d, e) at 500 °c and (f, g, h, i, k) at 650 °c. figure (19) shows the microscopic images of the aging samples at different temperatures and aging times. this is after being tested by immersion method, noting that there is almost no difference in the form of clicking and its size after aging at different temperatures and aging times; this is when compared to the pictures of the samples tested with the previously explained acceleration test as shown in figure (18). abdullah dhayea assi al-khwarizmi engineering journal, vol. 17, no. 1, p.p. 2033 (2021) 30 fig. 19. microscopic images of aging samples during different aging times ;(a) 1hr, (b) 5hr, (c) 10hr, (d) 15hr, (e) 20hr: immersion test where (a, b, c, d, e) at 500 °c and (f, g, h, i, k ) at 650 °c. 4. discuss the results 4.1 the relationship between the aging process and the microstructure . no residual austenite was observed in this type of stainless steel and rapidly cooled, probably because of the low residual austenite ratio of less than 2%; therefore, it did not appear in the microstructure and was not determined by x-ray diffraction . the remaining austenite (quasi-slice austenite) may appear in areas where the returning austenite was formed after hemolytic treatment, so a double needle-shaped microscopic structure consisting of low-carbon martensitic and recovered austenite may be formed in each martensitic slice [8]. it is known that in some types of martensitic stainless steel can be converted to austenite after aging at an aging temperature equal to or above 500 ° c [9]. the remaining austenite ratios were found to increase with the aging temperature and time up to 650 ° c, as shown in figures (3 and 4). it was also found that the amount of austenite was increased at the expense of martensitic by increasing the aging time above five hours at a temperature of 650 ° c; this means that the amount of martensitic converted to austenite remaining during the heating process at 650 ° c increased with the aging time. the volumetric ratio of the austenite after aging process decreases at 700 °c or above compared to the aging process at a temperature range of 500-650 °c as shown in figure (3); this means that the remaining part of the austenite formed at these temperatures turned again into an aging martensitic. aging at this temperature may have resulted in the deposition of chromium carbides cr23c6 and titanium carbides (tic) that consume carbon and depletion from martensitic and residual austenite [9]. this makes the austenite less stable and leads to the conversion of part of the remaining austenite to martensitic during cooling from 700 – 750°c to room temperature. after the rapid cooling process in the water, the microscopic structure of this sample consists of slices of martensitic and ferrite in the form of longitudinal ribs. the formation of high-density slice martensitic in this hardened stainless steel can be justified by precipitation at high temperature starting temperature of the martensitic conversion of ms = 120-150 °c as well as low carbon content in this steel, as it has been well proven that for various types of steels. the starting temperature of the martensitic transition and the ratio of carbon are the two most important factors that influence the structure and partial structure of martensitic and, in general, the martensitic with a slice structure is associated with a partial structure with a high intensity of dislocations [10]. it was found that aging samples were very deeply affected by the chemical smoothing solution as shown in figures (5 to 11). this is due to the appearance of residual austenite among the martensitic segments . exposure to the aging process at 500 ° c leads to a microscopic structure in which the martensitic bundles abdullah dhayea assi al-khwarizmi engineering journal, vol. 17, no. 1, p.p. 2033 (2021) 31 dissipate or dissolve clearly. the residual austenite appearance and increased quantity between the martensitic slices up to a temperature of 650 ° c reduces the slide width from about 3 microns to 0.5 microns. the microscopic structure after aging at 700 °c for 5 hours appears to consist of equal-dimensional granules (axes) as shown in figure (11). this may be due to the different range of transitions from chilled martensitic to residual austenite and martensitic no aging, as well as carbides in different granules. these differences make the boundaries of the martensitic bundles can be resolved and dissipated. 4.2 the relationship between microstructure and chemical corrosion behavior chemical corrosion behavior has been affected by the aging time and its temperature, as well as by the amount of remaining austenite and ferrite type delta, and also by the deposition of molybdenum and chromium carbides. aging-treated samples at 500 °c have maximum chemical corrosion rate values as shown in figure (12). this could be due to the presence of delta-type ferrite in the form of longitudinal ribs and the deposition of very small precipitates found to be molybdenum carbides (mo2c) [11]. after aging for 15 hours at 500 ° c, these carbides may begin to disintegrate and this leads to a decrease in the rate of chemical corrosion as shown in figures. (13 and16). aging samples at 550 °c have the lowest corrosion rate values as shown in figure (12), and this can be due to the high volumetric ratio of the austenite [12]. the resulting high rate of chemical corrosion after aging for 20 hours at 650 °c can be attributed to the beginning or growth of cr23c6 chromium carbide. after aging at temperatures above 650 ° c, carbides of cr23c6 type can become dominant, dominant and heterogeneous deposits in the martensitic floor that leads to an increase in the rate of chemical corrosion. aging in a range of (700 to 750) °c for 5 hours may precipitate cr23c6 carbides at the grain boundary as chromium atoms leave to form chromium-rich carbides. if these chromium-rich carbides are concentrated on the grain boundaries, there will be a decrease in the chromium content in the vicinity where the carbides begin to settle, forming the depletion areas of the chromium. the grains became more dangerous in their resistance to chemical corrosion [12]. the large flick size of aging samples at 500 °c as shown in figures (17b), (18) and (19b) indicates that these samples are more susceptible to fovea corrosion, which may be due to the formation of molybdenum carbides and the presence of delta type ferrite. it can be concluded that aging samples at 500 ° c for 5 hours are less predisposition than other samples, due to the small click size as indicated by doubt (17c,i) and can be due to high volumetric percentages it remains the result of the dissolution and disintegration of martensitic. the formation of chromium carbides of type cr23c6 in aging samples at 750 ° c has led to a second increase in the volume of clicking formed on the surface of aging samples at this temperature. 5. conclusions the main conclusions drawn from this research are the following : 1. the microscopic structure in rapidly cooled samples consists of slices of martensitic and longitudinal ribs of delta-ferrite and no residual austenite exists. 2. the remaining austenite begins to appear in the microstructure after aging at 500 ° c, and its volumetric ratios increase to its highest value after aging at 650 ° c. 3. the residual austenite volumes decrease from 32% to 20% by increasing the aging temperature from 650 to 750 °c. a portion of the remaining austenite is converted into an uncharacterized martensitic; this is cooled from 750 °c . 4. the chemical corrosion test was found to have three critical temperatures:  high corrosion rate at 500 °c due to the presence of delta -ferrite and mo2c carbides.  low corrosion rate at 500-650 ° c, due to high volumes of residual or anatomic .  average corrosion rate at 750 ° c as a result of deposition of chromium carbides and titanium in a small amount. 5. the aging temperature range from 500 to 650 ° c produced minimum localized corrosion that can be attributed to the high volumetric percentages of residual austenite. abdullah dhayea assi al-khwarizmi engineering journal, vol. 17, no. 1, p.p. 2033 (2021) 32 6. references [1] b. tzaneva, “effect of ph on the corrosion behaviour of high nitrogen stanless steel in chloride medium,” journal of chemical technology and metallurgy, 48, 4, 2013, pp 383390. [2] r. c. newman, “understanding the corrosion of stainless steel,” corrosion, vol. 57, no.12, dec. 2001, pp1030-1041. [3] k. ajay, s. chaudhary and a. sharma., “electrochemical studies of stainless steel corrosion in peroxide solutions”, portugaliae electrochimica acta, 2012, 30(2), 99-109. [4] j. tian, w. wang and m. babar, “a new maraging stainless steel with excellent strength–toughness–corrosion synergy”, materials 2017, 10, 1293; doi:10.3390/ma10111293 [5] a. nykiel and j. kazior, “effect of aging temperature on corrosion behavior of sintered 17-4 ph stainless steel in dilute sulfuric acid solution”, journal of materials engineering and performance (jmepeg), published online 15 june 2017. [6] c. h. beraldo, josé wilmar calderónhernández, rodrigo magnabosco and neusa alonso-falleiros, “effect of aging heat treatment h950 and h1000 on mechanical and pitting corrosion properties of uns s46500 stainless steel”, materials research. 2019; 22(1). [7] azo-material, the state of scientific marketing survey, " martensitic stainless steel, applications", november 1, 2018. [8] h. nakagawa, t. miyazaki and h. yokota, “effect of aging temperature on the microstructure and mechanical properties of 1.8cu-7.3ni-15.9cr-1.2mo-low c, n,martensitic precipitation hardening stainless steel,” journal of materials and science, 35, 2000, pp.2245-2253. [9] p. anja and k. axel, “local corrosion of martensitic stainless steels during exposure to saline aquifer water and co2 environment”, international journal of chemical engineering and applications, vol. 9, no. 1, february 2018. [10] d. deng,” microstructural study of 17-4ph stainless steel after plasma-transferred arc welding”, materials 2015, 8, 424-434; doi:10.3390/ma8020424. [11] z. de-ning., “influence of tempering process on mechanical properties of 00cr13ni4mo super martensitic stainless steel” j. of iron and steel research, international. 17(8), 2010, pp 50-54. [12] b. qin., “effect of tempering temperature on properties of 00cr16ni5mo stainless steel”, materials characterization, 59, 2008, pp 10961100. ) 2021(2033 ، صفحة 1، العدد17دجلة الخوارزمي الهندسية المجلمعبد هللا ضايع عاصي 33 المقاوم للصدأ مقاومة التآكل الكيميائي النقري للفوالذ تاثير التعتيق الحراري على دراسة المارتنسيتي دهللا ضايع عاصيعب بغداد –بغداد/ العراق –الجامعة التقنية الوسطى / معهد تكنولوجيا drabdullah_dhayea@mtu.edu.iq البريد االلكتروني: الخالصة   عينات اذ عرضتدراسة تأثير المعالجة الحرارية بالتعتيق في مقاومة التآكل الكيميائي النقري للفـوالذ المارتنسيتي المقاوم للصدأ، تم البحث في هذا إلى معالجة انحاللية عنـد درجـة حرارة للصدأ المقاوم المارتنسيتي الفوالذ إلى 1100من ثم سخنت بالماء ومن درجة درجة مئوية مدة ساعة وغطست ) ساعة. اجري اختبار التآكل الكيميائي المسرع واختبار التآكل الكيميائي بالغمر 20-1) درجة مئوية لمدد إبقاء متنوعة ( 750500حرارة ضمن المجـال ( أن العينات المعتقة عند درجة على العينات بعد المعالجة الحرارية . بينت نتائج البحث تأثر مقاومة التآكل النقري تأثرًا كبيرًا بدرجة حرارة التعتيق، ِإِْذ وجد فرايت) وترسبات ناعمة جدًا من أطوار أخرى بشكل δعظم معدل تآكل الذي قد يكون بسبب زيادة نسبة فرايت نوع دلتا (درجة مئوية تملك ا 550حرارة درجة ) 650–550غيـر متجانس فـي الطـور األساسـي المارتنسيتي؛ مما يؤدي إلى زيادة معدل التآكل، في حين العينات المعتقة في مجال درجة حـرارة ( درجة 650عدل تآكل أصغر، ويعزى ذلك إلى النسبة الحجمية المرتفعة لألوستنيت المتبقي . وتبدي العينات المعتقة عند درجة حرارة أعلى من مئوية لها قيم م نوع الفريت بشكل يتعلق ال وشكلها الكيميائي التآكل اختباري كال عن الناتجة النقر نوع أن كذلك ووجد متوسطا. تآٍكٍل معد ََل والكربيدات دلت مئوية ا الموجودة في البنية المجهرية. this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 19, no. 1, march, (2023) p. p. 5769 design a radio receiver for solar activity observation in vlf band ahmed al banna department of information and communication engineering/ al-khwarizmi college of engineering/ university of baghdad / iraq email: akadhim@kecbu.uobaghdad.edu.iq (2022 november 30 2022; accepted march 17received ) https://doi.org/10.22153/kej.2023.11.002 abstract solar activity monitoring is important in our life because of its direct or indirect influence on our life, not only on ionospheric communications. to study solar activity, researchers need measuring and monitoring instruments, these instruments are mostly expensive and are not available in all universities. in this paper, a very low frequency radio receiver had been designed and implemented with components available in most markets to support the researchers, college students, and radio astronomy amateurs with a minimum input voltage less than 100µv, an output voltage less than 135 m v with no distortion and an overall gain of 34db. a comparison had been done between two circuit structures using a workbench software program and experimentally done in the lab. two antennas were experimentally tested and a loop antenna was chosen. the whole system was connected and tested to receive signals in the lab and monitored on computer using hdsdr software program. another experiment done outside the lab (at home), and the result was not good because of many high level interference noises. keywords: solar activity, ionospheric communication, very low frequency radio receiver. 1. introduction the philosophy behind designing a very low frequency (vlf) receiver with a bandwidth of 10 to 40 khz is to monitor the flare event indirectly by receiving the signals of distant vlf transmitters worldwide that are used for marine navigation and studying natural phenomena [1]. studying solar flares is important because they have an effect on devices and infrastructures in this era [2, 3]. these signals propagate in ground wave and sky wave paths [4]. sky wave propagation paths only occur in night time in normal solar conditions, while for distances less than 700km, ground wave propagation is more dominant [5]. if high solar activity flares occur, they will increase the ionization levels of these layers when they reach the earth’s ionosphere, making the d layer more ionized and absorption levels will also increase [6]. at this moment, the d layer absorbs signals from 3 to 30 mhz and this is called high frequency (hf) block out, while signals from 10 to 40 khz will be reflected to a distance less than 2000 km in day time making the d layer a reflector mirror. by receiving a distant station (sky wave propagation) at day time from 10 to 40 khz using a vlf radio receiver, it is an indirect indicator that a flare has occurred. in previous works [1-6], the circuits were designed using high cost components, software programs, and antenna systems, which is a problem facing researches in countries like iraq, so the novelty in this paper is to design a vlf receiver from components available in the iraqi markets. 2. methodology 2.1 monitoring scenario vlf beacons exist worldwide, and are used for marine navigation. for demonstration purposes, a bafa transmitter (beacon) located in turkey with callsign tbb at a frequency of 26.7 khz had been mailto:akadhim@kecbu.uobaghdad.edu.iq https://doi.org/10.22153/kej.2023.11.002 ahmed al banna al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 5769 (2023) 58 taken as a transmitter, and the vlf receiver is located in baghdad. at day time in baghdad, the receiver will not receive the signal at that frequency, but at night time with good ionosphere conditions and good antenna alignment, it could receive the signal of that transmitter. if tbb is heard at daytime in baghdad it means that the signal was reflected from the d layer with a high degree of ionization because of solar flare occurrence. 2.2 simulation a vlf receiver’s block diagram consists of an antenna, a preamplifier of 14db gain, a main amplifier of 20 db gain, and the amplified signal is displayed using computer software like hdsdr, which is a free license software defined radio program under windows used for many applications like radio astronomy, shortwave listening, spectrum monitoring, and analysis, as shown in fig. 1. fig. 1 shows vlf block diagram. the vlf receiver had been simulated using the electronics workbench software, version 5.12. fig. 2. shows the simulated preamplifier circuit diagram. the circuit in fig. 2 consists of a low pass filter (lpf) of corner frequency (fc) around 40 khz, and a jfet transistor (bf245b) in common source configuration with a gain of around 14 db. the simulated results of the amplifier frequency response and vo versus (vs.) vin are summarized in fig. 3 and 4. ahmed al banna al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 5769 (2023) 59 fig. 3. shows the simulated frequency response of the preamp. fig. 4. shows the simulation of vo vs. vin. fig. 4 shows the relation of vo vs. vin (that was generated using the electronic workbench simulation program) which is a liner gain relationship of common source amplifier of the circuit in fig. 2, in which the gain formula is simply illustrated in equation 1 as follows [7]: 𝑉𝑜 = −𝑔𝑚𝑉𝑖𝑅𝐷 … (1) where vo is the output voltage, vin is the input voltage, gm transistor is the transconductance, and the rd is the drain resistor. the main amplifier circuit of fig. 1 had been simulated using two designs, the first (design consists of a bpf of bw=30khz and a bjt transistor (2n2222) in the common emitter configuration of 20 db gain, as shown in fig, 5. the simulated frequency response and vo vs. vin is summarized in fig. 6 and 7. ahmed al banna al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 5769 (2023) 60 fig. 5. shows the simulated main amplifier (1st design). fig. 6. shows the simulated frequency response of the main amplifier (1st design). fig. 7. shows the simulation of vo vs. vin of the main amp. (1stdesign) the second design consists of a tuned common amplifier with a variable inductance coil from 5mh to 8 mh, as shown in fig. 8. the simulated frequency response and vo vs. vin is summarized in fig. 9 and 10. ahmed al banna al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 5769 (2023) 61 fig. 8. shows the simulated main amplifier (2nd design). fig. 9. shows the simulated frequency response of the main amplifier (2nd design). fig. 10. shows the simulation of vo vs. vin of the main amp. (2nd design). 2.3 laboratory experiments at the lab, the circuit in fig. 2 had been tested by connecting it to the function generator; model utg9002c-ii, as shown in fig. 11. the input voltage (vin) kept constant to 10 mvp while the frequency varied from 10 to 40 khz, and the output voltage (vo) was displayed using an oscilloscope uni-t; model utd2025cl. the practical frequency response and vo vs. vin is shown in fig. 12 and 13. ahmed al banna al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 5769 (2023) 62 fig. 11. shows the preamp. circuit connected in the lab. fig. 12. shows the practical frequency response of the preamp. fig. 13 shows the practical vo vs. vin of the preamp. ahmed al banna al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 5769 (2023) 63 a 50cm whip antenna had been connected to the function generator. at a distance of 50cm, the circuit of fig. 11 had been placed and a 50 cm whip antenna had been used. the frequency varied from 10 to 40 khz, and the frequency response was measured as shown in fig. 14. fig. 14. shows the frequency response of the preamp. circuit with a whip antenna. a loop antenna with a radius of 20 cm was used instead of the whip antenna of the receiver, and the experiment was repeated. fig. 15 summarizes the result . fig. 15. shows the frequency response of the preamp. circuit with a loop antenna. figs 16 and 17 show that the lab versions of the simulated circuits of figs 5 and 8 had been connected, and the results of the frequency responses are summarized in figs 18 and 19. the vo vs. vin relationships are summarized in figs 20, 21. 0 0.5 1 1.5 2 2.5 3 3.5 10 100 v o /m v p p freq./khz freq. responce with whip antenna of preamp 0 1 2 3 4 5 6 7 8 10 100 v o /m v p p frequency/khz freq. responce with loop antenna of preamp. ahmed al banna al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 5769 (2023) 64 fig. 16. shows main amp. circuit (1st design) connected in the lab fig. 17. shows main amp. circuit (2nd design) connected in the lab fig. 18. shows the practical frequency response of the main amplifier (1st design). 0 100 200 300 400 500 10 100 v o /m v p frequency/khz practical main amp. 1st design frequency response @10mvp vin ahmed al banna al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 5769 (2023) 65 fig. 19. shows the practical frequency response of the main amplifier (2nd design). fig. 20. shows the practical vo vs. vin relationship of the main amp. (1st design). fig. 21. shows the practical vo vs. vin relationship of the main amp. (2nd design). 0 500 1000 1500 2000 2500 10 100 v o / m v p frequency / khz practical main amp. 2nd design frequency response @10mvp vin 0 50 100 150 200 250 300 350 400 450 1 2 3 4 5 6 7 8 9 10 v o / m v p vin/mvp practical vo vs. vin @20khz 0 500 1000 1500 2000 2500 1 2 3 4 5 6 7 8 9 10 v o / m v p vin/mvp practical vo vs. vin @20khz ahmed al banna al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 5769 (2023) 66 fig. 22. shows the practical vo vs. vin relationship in both designs. in fig. 23, a whole vlf receiver was connected consisting of a loop antenna, the preamplifier of fig. 11, and the main amplifier (2nd design) of fig. 17. the output signal was displayed on a computer using the hdsdr software . fig. 23 shows the complete vlf radio receiver the system was tested in the lab. a signal of 20 khz was transmitted using the function generator, and the output was displayed on an hdsdr screen, as shown in fig. 24. fig. 24. hdsdr screen shows signal received in lab. 0 500 1000 1500 2000 2500 1 2 3 4 5 6 7 8 9 10 v o / m v p vi/mvp practical vo vs. vi gain @20khz circuit 1 gain@20khz circuit 2 gain@20khz ahmed al banna al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 5769 (2023) 67 the received experiment was repeated outside the lab environment (at home). the environment was so noisy, and the results are summarized in figs 25 and 26. fig. 25. hdsdr screen shows noise signals received at home (day time). fig. 26. hdsdr screen shows noise signals received at home (night time). 3. discussion from the simulation and experiments, using a loop antenna was better than using a whip antenna (had more gain), and the 2nd design of the main amplifier was better than 1st design (had a better frequency response). fig. 10 shows that the transistor works in linear regions if vin < 8mvp, while it works in saturation regions with a distorted vo when vin> 8 mvp [a]. fig. 21 shows that the transistor works in linear region (almost, with the hfe measured at 205). fig. 24 shows the received signal (in a lab environment) from the function generator as a transmitter, while in figs 25 and 26 environmental noises had significant levels that effected the received signals because of man made noises like cell phone chargers, laptop chargers, leds lights etc. 4. conclusion in this work, a vlf receiver structure had been proposed. a comparison between electronic workbench v5.1 and lab results had been done. comparisons between two types of antennas had been done and the loop antenna was chosen. a complete system had been tested in two different environments, lab and home environments, and displays the received signal on a computer using hdsdr software program. finally, to receive a flare with a high degree of success, it is better to setup the receiver outside the town (in rural area), because experimentally, the receiver failed to detect flare events in home environment because noise signals had significant levels which showed in the hdsdr software’s program screen. acknowledgment the author is grateful to the information and communication engineering department /al khwarizmi college of engineering / university of baghdad for allowing the using their electronic and communication lab for the implementation and the testing of the vlf receiver circuits. ahmed al banna al-khwarizmi engineering journal, vol. 19, no. 1, p.p. 5769 (2023) 68 5. references [1] suryadi, m. abdullah, h. husain,”development of vlf receiver for remote sensing of low atmospheric activities”, international conference on space and communication, port dickson, malaysia, 2009. 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(2023) 57-69، صفحة 1، العدد19الخوارزمي الهندسية المجلدمجلة احمد كاظم حسن 69 اراديوي لمراقبه النشاط الشمسي ضمن حزمة الترددات المنخفضة جدتصميم مستلم احمد كاظم حسن البناء قسم هندسة المعلومات واالتصاالت/ كلية الهندسة الخوارزمي/ جامعة بغداد akadhim@kecbu.uobaghdad.edu.iq:يالبريد االلكترون الخالصة فقط على االتصاالت االيونوسفيرية وانما على الحياة ايضا. مباشرة ليسمراقبة النشاط الشمسي يعتبر مهم لحياتنا الن تغيره يؤثر بصورة مباشرة وغير في هذا البحث تم تصميم مستلم راديوي الجامعات.وهذه المعدات هي غاليه الثمن والتتوفر بكل ومراقبة،لدراسة النشاط الشمسي يحتاج الباحثون معدات قياس االخراج ةوفولتي ،مايكروفولت 100دخول اقل من ةفولتي بأقلطلبه الكليات وهواه الفلك الراديوي الباحثين،في االسواق ليدعم ةتم تنفيذه من عناصر متوفر وتم مختبريا تنفيذهما. هوائيان تم قد تمت workbenchمقارنة بين دائرتين باستخدام برنامج الديبي. 34ملي فولت بال تشوه وكسب كلي بحدود 135اقل من على الحاسوب باستخدام برنامج اإلشارةالمختبر وعرض تم ربط النظام بأجمعه واختباره الستالم االشارات في الحلقي.اختبارهما وتم اختيار الهوائي hdsdr عالية المستوى من الضوضاءوالنتيجة كانت غير جيدة بسبب تداخل العديد )منزليا(. تم تنفيذ تجربة اخرى خارج المختبر. mailto:akadhim@kecbu.uobaghdad.edu.iq <4d6963726f736f667420576f7264202d20e5e4cf20e6e3d1e6ec20dec7d3e320e6c7cde3cf31352d3235> this is an open access article under the cc by license: al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 18, no. 3, september, (2022) p. p. 1525 performance prediction in edm process for al 6061 alloy using response surface methodology and genetic algorithm hind hadi abdulridha* marwa qasim ibraheem** ahmed ghazi abdulameer*** *,**,***department of production engineering and metallurgy/ university of technology/ baghdad/ iraq *email: hind.h.abdulridha@uotechnology.edu.iq **email: 70223@uotechnology.edu.iq ***email: ahmed.g.taki@uotechnology.edu.iq )2022 10 august; accepted 22027 march received ( https://doi.org/10.22153/kej.2022.08.001 abstract the electric discharge (edm) method is a novel thermoelectric manufacturing technique in which materials are removed by a controlled spark erosion process between two electrodes immersed in a dielectric medium. because of the difficulties of edm, determining the optimum cutting parameters to improve cutting performance is extremely tough. as a result, optimizing operating parameters is a critical processing step, particularly for non-traditional machining process like edm. adequate selection of processing parameters for the edm process does not provide ideal conditions, due to the unpredictable processing time required for a given function. models of multiple regression and genetic algorithm are considered as effective methods for determining the optimal processing variables of electrical discharge machining. the material removal rate (mrr) and tool wear (tw) were investigated using the process variables of pulse on time (ton), pulse off time (toff), and current intensity (ip). the established empirical models were used to perform genetic algorithm (ga) to maximize (mrr) and minimize (tw). the optimization results were utilized to establish machining conditions, validate empirical models, and obtain optimization outcomes. the optimal result that appears in this work was the pulse on (176.261 μs), pulse off (39.42 μs), and current intensity (23.62 amp.) to maximize the mrr to (0.78391 g/min) and reduce tool wear to (0.0451 g/min). keywords: electro discharge machining, genetic algorithm, mrr, tool wear. 1. introduction machining aluminum alloy using traditional machining technologies has problems such as high cutting temperatures and a high tool wear ratio. aluminum is employed in a variety of industries, including automobiles, and aerospace. aluminum alloy, on the other hand, has some advantages due to its low cost, low density, availability, and manufacturability [1]. aa 6061 aluminum alloy is a precipitationhardened variant of the 6000 series al alloys that are widely used. it's a heat-treatable extruded alloy with medium to high strength properties [2]. electrical discharge machining (edm) is a non-traditional machining technique that is commonly used to machine die surfaces [3]. edm is a popular production technique for difficult-to-machine materials and complex geometries. wire and electrode edm are the two primary types of edm processes. the manufacturing process setup includes the electrode material, the geometry of wire diameter or the electrode, and the energy transfer parameters of voltage v with its polarity, pulse current intensity i, and pulse on time (ton) and pulse off time (toff) [4][5]. several authors attempted to machine several hind hadi abdulridha al-khwarizmi engineering journal, vol. 18, no. 3, p.p. 1525 (2022) 16 materials by utilizing the electrical discharge machining process. s. ranjith et al. [6] examined the influence of edm machining variables (pulse-on duration, current, pulse-off duration, and spark gap voltage) on mrr and tw of silicon nitride–titanium nitride ceramic composites with the copper electrode. from the results, it has been shown that the current is a highly important factor among other parameters on both mrr and twr. higher material removal rate is obtained when pulse-on time and current is higher, whereas lower ewr result from high gap voltage and low current. huuphan et al. [7] applied multi-response optimization based on technique for order of preference by similarity to ideal solution (topsis) to examine the impact of lowfrequency vibration on material removal rate mrr and surface roughness ra in edm process. from the experimental results, in the low-frequency vibration aided edm technique, the process performance accuracy has been enhanced to around 86.6 percent. by enhancing the quality of the machining surfaces, topsis was able to improve the low-frequency vibration-assisted edm process' performance. the material removal rate can be increased with low-frequency vibration due to the controlled spark energy. mandeep and sthitapragyan [8] examined the effects of machining parameters such as pulse-on time (t-on), pulse-off time (toff), current (i), and voltage (v) on the mrr of aluminum based composite material. the aluminum metal matrix composite was cast with 200 mesh size (avg. size 75 mm) particles (20 percent sicp and 8% grp). response surface methodology rsm created the design matrix and mathematical models. the experimental results indicate that the pulse-on time and current are both major factors that directly affected (increased) the material removal rate, according to the analysis. finally, at a high level of "pulse-off time," the mrr is minimal, but "voltage" has no significant effect on mrr. mandeep et al. [9] determined the optimum process parameters (peak current (i), voltage (v), ton, and tool material) that affect the mrr and ra of edm during the machining of a new hybrid aluminum metal matrix composite. from the analysis of variance (anova), the mrr increased as the ton and pulse current increased, however, the mrr declined as the voltage increased. reduced ra, on the other hand, could only be achieved with low i, v, and pulse length. it was also revealed that the electrodes used in edm had a substantial impact on mrr and surface roughness. chinmayee et al. [10] investigated the influence of input parameters (discharge current, pulse-on-time, and open circuit voltage) on mrr, tw and radial overcut of aa 7075 aluminum6% red mud metal matrix composites (ammc) in the edm process. from the results, it has been observed that pulse on-time and discharge current have a crucial influence on machinability characteristics of (ammc) by providing useful information with less deviation to improve the accuracy of the edm parts. ramanuj et al. [11] carried out an experimental investigation to study the effect of (voltage, pulse on time, and current) on the (ra) and (mrr) of ti-6al-4v eli using edm. multi response grey relation analysis (gra) technique has been utilized for optimizing the machining parameters. from the results, it has been presented that the mrr and ra were directly proportional to discharge current. sagar and pravin [12] provided an experimental investigation on the effect of (pulse on duration, discharge voltage, capacitance, and electrode rotation speed) on side gap width, mrr, and taper ratio when drilling titanium alloy (ti6al4v) with copper tungsten (cuw) electrode. the experimental results demonstrate that capacitance, discharge voltage, and electrode rotation speed all have an impact on mrr parameters, whereas pulse on time, capacitance, and electrode rotation speed influence side gap width. on the other hand, capacitance and pulse on duration were the affecting parameters on the taper ratio. r.rajesh and m. dev anand [13] calculated the optimum operating parameters namely; working voltage, oil pressure, spark gap, pulse on time, and pulse off time, affecting the mrr by developing genetic algorithm and multiple regression models with an empirical model by conducting experiments based on the grey relational analysis, which were used to obtain the greatest value for mrr in electric discharge machine. tzeng et al. [14] analyzed mrr, electrode wear ratio, and workpiece surface finish on process parameters during the manufacture of skd61 by electrical discharge machining (edm). a hybrid method including a back-propagation neural network (bpnn), a genetic algorithm (ga), and response surface methodology (rsm) were proposed to determine optimal parameter settings of the edm process. hind hadi abdulridha al-khwarizmi engineering journal, vol. 18, no. 3, p.p. 1525 (2022) 17 in this paper, the influence of edm parameters (pulse on time ton (μs), pulse off time toff (μs) and current intensity ip (a)) was studied to determine their influence on the material removal rate (mrr) and tool wear rate (tw) values based on response surface methodology (rsm) and genetic algorithm. 2. experimental work a chemer edm machine model (cm-323 c) as shown in figure 1, is used to implement the experimental work. fig. 1. edm tool model cm 323c fig. 2. work piece samples of al-6061 alloy 2.1 work piece material for evaluating the optimum values of process variables, a copper electrode was used to machine twenty samples of aa 6061 aluminum alloy with dimensions (15×15×5mm) as shown in figure 2. table 1 illustrates the chemical composition of aa 6061 alloy. table 1, al-6061 alloy chemical composition sample workpiece material cu % 0.388 fe % 0.195 si% 0.49 mg % 1.07 mn % 0.068 zn % 0.003 cr% 0.243 ti% 0.019 al% balance 2.2 selection parameters and their levels process variables are the parameters that influence material removal rate (mrr) and tool wear rate (tw) of machined surface and include the current intensity (ip), pulse on time (ton), and pulse off time (toff). table 2 shows the parameters values and their levels that were used in the experiments. table 2, parameters values and the levels used process parameters pulse on time ton (μμμμs) pulse off time toff (μμμμs) current intensity ip (amp.) levels low 100 25 8 medium 150 37 16 high 200 50 24 2.3 design and analysis of experimental work to find which input parameters generate the optimum output and to identify the influence of input parameters that enhance the developed qualities of the part above the obtained qualities, rsm was adopted to in this study to develop statistical and mathematical models due to its reliable performance [15, 16]. the central composite design is the most frequent way of hind hadi abdulridha al-khwarizmi engineering journal, vol. 18, no. 3, p.p. 1525 (2022) 18 building a quadratic model of a response surface (ccd). experiments are conducted with rsm and a central composite design (ccd) matrix with two-level factorial (full factorial) where it consists of 8 cube points, 6 center points, and 6 axial points with α=1.68179. experimental design is an important stage in creating a response surface model using minitab software[15]. material removal rate (mrr) and tool wear rate (tw) are calculated from equations (1,2) [17, 18] after experimentation, as shown in table 3. mrr = ���� ��� � ��� �� ��������� ���� ���� �� ��� ����� … (1) t� = ���� ��� � ��� �� ��� ���� ���� �� ��� ����� … (2) table 3, experimental results of (mrr), (tw) tw (g/min) mrr (g/min) ip toff ton no. 0.0024 0.0790 8 25 100 1 0.0023 0.0820 8 25 200 2 0.0013 0.0700 8 50 100 3 0.0010 0.0760 8 50 200 4 0.0100 0.5040 24 25 100 5 0.0130 0.6890 24 25 200 6 0.0048 0.4952 24 50 100 7 0.0231 0.5300 24 50 200 8 0.0065 0.3050 16 37 100 9 0.0069 0.4160 16 37 200 10 0.0130 0.3845 16 25 150 11 0.0130 0.3540 16 50 150 12 0.0015 0.0810 8 37 150 13 0.0120 0.6300 24 37 150 14 0.0069 0.3800 16 37 150 15 0.0069 0.3800 16 37 150 16 0.0069 0.3800 16 37 150 17 0.0069 0.3800 16 37 150 18 0.0069 0.3800 16 37 150 19 0.0069 0.3800 16 37 150 20 3. results and discussion 3.1. analysis of variance on the basis of table 3's experimental findings, the impact of the input variables (ton), (toff), and (ip) on the outputs (mrr and tw), is investigated using minitab 17 software and analyses of variance (anova). the significance of the model is determined using anova. the anova results for mrr and tw are shown in tables 4-5, respectively. hind hadi abdulridha al-khwarizmi engineering journal, vol. 18, no. 3, p.p. 1525 (2022) 19 table 4, anova of mrr source df adj ss adj ms f-value p-value model 9 0.648477 0.072053 118.07 0.000 linear 3 0.620442 0.206814 338.91 0.000 ton 1 0.011445 0.011445 18.75 0.001 toff 1 0.004550 0.004550 7.46 0.021 ip 1 0.604448 0.604448 990.51 0.000 square 3 0.015405 0.005135 8.41 0.004 ton*ton 1 0.001454 0.001454 2.38 0.154 toff*toff 1 0.000493 0.000493 0.81 0.390 ip*ip 1 0.002155 0.002155 3.53 0.090 2-way interaction 3 0.011331 0.003777 6.19 0.012 ton*toff 1 0.002771 0.002771 4.54 0.059 ton*ip 1 0.005555 0.005555 9.10 0.013 toff*ip 1 0.003005 0.003005 4.92 0.051 error 10 0.006102 0.000610 lack-of-fit 5 0.006102 0.001220 * * pure error 5 0.000000 0.000000 total 19 0.654580 s = 0.0247030, r-sq = 99.07%, r-sq(adj) = 98.23%, r-sq(pred) = 85.78% fig. 3. mrr main effects plot. fig. 4. tw main effects plot 200150100 0.6 0.5 0.4 0.3 0.2 0.1 503725 24168 ton m e a n toff ip main effects plot for mrr data means 200150100 0.014 0.012 0.010 0.008 0.006 0.004 0.002 503725 24168 ton m e a n toff ip main effects plot for twr data means hind hadi abdulridha al-khwarizmi engineering journal, vol. 18, no. 3, p.p. 1525 (2022) 20 it is clear from the main effects plot of figure 3 that the material removal rate highly increases with the increase of current intensity, and decreases with the increase in pulse on time and pulse off time, the reason behind this is that the discharge energy increases with the increase of pulse on time and peak current leading to a faster cutting rate. with the decrease in the pulse off time, the number of discharges within a given period becomes more which leads to a higher material removal rate. to depict the input variables relationship between (ton, toff, and ip) and the output (mrr), material removal rate mathematical model is established as in equation 3. mrr = -0.714 + 0.00350 ton + 0.01230 toff + 0.04211 ip 0.000009 ton*ton 0.000086 toff*toff 0.000437 ip*ip 0.000030 ton*toff + 0.000066 ton*ip 0.000194 toff*ip … (3) table 4 shows the overall significance of the mathematical model, with (r-sq) determining the fit value between predicted and experimental findings. the (r-sq(adj)) value indicates that the independent variables (ton, toff, and ip) recorded (98.23) percent of the variance in the dependent variable (y), with the remainder due to random error. table 5, anova of tw source df adj ss adj ms f-value p-value model 9 0.000522 0.000058 7.41 0.002 linear 3 0.000388 0.000129 16.52 0.000 ton 1 0.000091 0.000091 11.61 0.007 toff 1 0.000001 0.000001 0.08 0.783 ip 1 0.000297 0.000297 37.88 0.000 square 3 0.000042 0.000014 1.79 0.213 ton*ton 1 0.000001 0.000001 0.13 0.730 toff*toff 1 0.000018 0.000018 2.26 0.163 ip*ip 1 0.000038 0.000038 4.81 0.053 2-way interaction 3 0.000094 0.000031 3.98 0.042 ton*toff 1 0.000028 0.000028 3.58 0.088 ton*ip 1 0.000059 0.000059 7.52 0.021 toff*ip 1 0.000007 0.000007 0.85 0.377 error 10 0.000078 0.000008 lack-of-fit 5 0.000078 0.000016 * * pure error 5 0.000000 0.000000 total 19 0.000600 s = 0.0027986, r-sq = 86.96% , r-sq(adj) = 75.22%, r-sq(pred) = 0.00% it is also clear from the main effects plot of figure 4 that the most influencing factor on tool wear rate is the peak current; tool wear rate is minimum at lower currents. to depict the input parameters relationship between (ton, toff, and ip) and the output (tw), tool wear rate mathematical model is established as in equation 4. tw = 0.0397 0.000232 ton 0.001797 toff + 0.001171 ip + 0.000000 ton*ton + 0.000016 toff*toff 0.000058 ip*ip + 0.000003 ton*toff + 0.000007 ton*ip + 0.000009 toff*ip … (4) table 5 shows the overall significance of the mathematical model, with (r-sq) determining the fit value between predicted and experimental findings. the (r-sq(adj)) value indicates that the independent variables (ton, toff, and ip) recorded (75.22) percent of the variance in the dependent variable (y), with the remainder due to random error. figure 4 shows the tw main effects plot. hind hadi abdulridha al-khwarizmi engineering journal, vol. 18, no. 3, p.p. 1525 (2022) 21 3.2 ga results genetic algorithm is a probabilistic search technique that generates a new population from an iterative collection (called a population) of mathematical objects (typically fixed-length binary character strings), each with a fitness value [19]. the genetic algorithm analyzes the experimental and expected values by using the intersection technique and the best value is supplied in the schedule below. genetic algorithm input population size=50 population type=double vector no. of generations = 50 no. of generations chosen = 15 fitness function =rank scaling cross function = two-point cross over fraction of = 0.8 mutation function = adaptable feasible the best results were obtained after choosing the fitness function for a total length of the string of 18 and then transferring the results to matlab after setting up ga parameters and presenting them in table 6. table 6, ga that results for mrr, tool wear no. ton toff ip mrr tw rank 1 100.231 25.263 9.41 0.063425 0.0025 1 2 123.451 29.421 13.44 0.0736586 0.0031 1 3 110.275 35.781 17.23 0.0208128 0.0071 1 4 133.651 38.621 16.42 0.3721823 0.0097 1 5 144.573 38.689 18.931 0.46217 0.0187 1 6 176.261 39.42 23.623 0.78391 0.0451 1 7 157.621 33.465 12.217 0.11327 0.0037 1 8 167.951 43.26 19.425 0.53217 0.02321 1 9 172.651 46.72 15.621 0.27218 0.0110 1 10 155.621 35.621 17.631 0.43218 0.0132 1 11 143.679 42.631 18.965 0.49265 0.0211 1 12 175.692 47.345 22.31 0.61329 0.032 1 13 199.200 37.625 16.781 0.39781 0.0197 1 14 184.222 48.681 19.678 0.59232 0.0232 1 15 137.437 28.42 14.597 0.21379 0.0111 1 fig. 5. the implemented data on ga hind hadi abdulridha al-khwarizmi engineering journal, vol. 18, no. 3, p.p. 1525 (2022) 22 table 7, the optimum solution for several values of ga parameters number of iteration crossover mutation optimal solution best mean 1 2 3 4 5 0.6 0.6 0.6 0.6 0.6 0.04 0.05 0.06 0.07 0.08 1.356321 1.366012 1.369412 1.477213 1.478231 1.356453 1.367432 1.373211 1.477631 1.478912 6 7 8 9 10 0.75 0.75 0.75 0.75 0.75 0.04 0.05 0.06 0.07 0.08 1.565221 1.572132 1.575423 1.579543 1.594352 1.566321 1.572322 1.576421 1.582311 1.596432 11 12 13 14 15 0.8 0.8 0.8 0.8 0.8 0.04 0.05 0.06 0.07 0.08 1.653211 1.663214 1.594231 1.694325 1.82274 1.662132 1.673421 1.594326 1.694321 1.82281 providing better reproductive opportunities through offspring gives more possible solutions so table 7 shows that the increase in the crossover value caused improvement in the results until it reaches the optimal values, where reading no (15) in table 7 showed the best fitness (1.82274) and mean fitness (1.82281) which was evident in the figure 5 that represents the implementation of the program. the pulse on time, pulse off time, and current intensity were all optimized. the aim here is to reduce tool wear while increasing the rate of material removal. the following are the boundary conditions for the decision variables pulse on time, pulse off time, and current intensity: pulse on time (ton) = (100 to 200 μs) pulse off time (toff) = (25 to 50 μs) current intensity (ip) = (8 to 24 amp.) figures 6-7 illustrate the effect of (toff) on mrr and tool wear, where its increase in toff led to an increase in mrr to optimal value (0.78391 g/min) at toff (39.42 μs) with a decrease in tool wear by (0.0451 g/min), while figures 8-9 indicate the effect of current intensity on mrr and tw, respectively the optimal values was at ip (23.623 amp.). fig. 6. effect of pulse off time on mrr. fig. 7. effect of pulse off time on tw. 0 20 40 60 1 3 5 7 9 11 13 15 t o ff ( μ s) experiment no. toff (μs) 0 20 40 60 1 3 5 7 9 11 13 15 t o ff ( μ s) experiment no. toff (μs) tw (g/min) hind hadi abdulridha al-khwarizmi engineering journal, vol. 18, no. 3, p.p. 1525 (2022) 23 fig. 8. effect of current intensity on mrr. fig. 9. effect of current intensity on tw. 4. conclusions this research presents a realistic method for optimizing edm cutting parameters based on ga. the machining parameters included pulse on, pulse off, and current intensity ip. the edm method yields results such as metal removal rate and tool wear. the response surface method (rsm) uses statistical and mathematical methods for issue modeling and analysis to locate the input variables that generate the optimum response. finally, ga was able to determine the best circumstances. that is, between experimental data, pulse on (176.261 μs), pulse off (39.42 μ s), current intensity (23.62 amp.) to maximize the mrr to (0.78391 g/min) and reduce tool wear to (0.0451 g/min). the machining current of the edm process is the most influential factor revealed by the response table. 5. references [1] a. elanthiraiyan, g. antony, s. ashok and s. sathiyaraj,"investigation of machining characteristics of aluminum 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[14] tzeng, cj.and chen, ry., "optimization of electric discharge machining process using the response surface methodology and genetic algorithm approach", ijpem, 14, 709–717, 2013. [15] v. devkumar, e. sreedhar and m.p. prabakaran, "optimization of machining parameters on al 6061 alloy using response surface methodology", ijar, 1 (7), 01-04, 2015. [16] r. myers, d. montgomery and c. anderson-cook, response surface methodology process and product optimization using designed experiments, john wiley & sons publication, 3rd edition, 2009. [17] m. tiwan, k. mausam, k. sharma, r. pratap,"investigation the optimal combination of process parameters for edm by using a grey rational analysis", amme, 2014. [18] r. rudrapati, p. sahoo and a. bandyopadhyay, "optimization of process parameters in cnc turning of aluminium alloy using hybrid rsm cum tlbo approach", iop conf. series: materials science and engineering, 2016. [19] p. jayaraman, l. mahesh and v. senthil, "optimization of cutting parameters in turning of aa6351 using response surface methodology and genetic algorithm", ijaer, 10 (23), 4390543911,2015. )2022( 15-25، صفحة 3العدد ، 18مجلة الخوارزمي الهندسية المجلد فاطمة محمد جاسم 25 وتأكل المعدن ازالة بمعدل للتنبؤ االستجابة سطح منهجية مع الجينية الخوارزمية تقنية االداة في عملية التشغيل بالشرارة الكهربائية **مروى قاسم ابراهيم * هند هادي عبد الرضا ***احمد غازي عبد االمير *،**،*** قسم هندسة اإلنتاج والمعادن/ الجامعة التكنولوجية hind.h.abdulridha@uotechnology.edu.iqااللكتروني: *البريد 70223@uotechnology.edu.iq :البريد االلكتروني** ahmed.g.taki@uotechnology.edu.iq : ***البريد االلكتروني خالصة ال متحكم شرارة تكوين عملية طريق عن المواد إزالة فيها يتم جديدة ة كهر وحراري تصنيع تقنية هي) edm( التشغيل بالشرارة الكهربائية طريقة . للغاية صعب أمر القطع أداء لتحسين القطع متغيرات أفضل تحديد فإن ، edm صعوبات عملية بسبب . عازل وسط في مغمسين قطبين بين بها التحديد المناسب لمتغيرات إن . edm لمث التقليدية غير ال لعمليات التشغيل خاصة حاسمة، خطوة التشغيل متغيرات امثل إيجاد يعد لذلك، نتيجة المتعدد االنحدار نماذج إنشاء تم . لصعوبة التنبؤ بوقت المعالجة المطلوب للمهمة المعطاة هذه العملية ربما ال يعطي الظروف المثلى نظرا المواد إزالة معدل التحقق من تم . المشكلة لحل هذه الكهربائي التفريغ معالجة في المثلى المعالجة متغيرات لتحديد فعالة كطرق جينيةال خوارزميةالو )mrr (األداة معدل بليانو )tw (النبضةتشغيل زمن وهي: العملية متغيرات باستخدام )ton،( النبضة إطفاءزمن و )toff،( التيار وشدة )ip .(الجينية الخوارزمية إلى المستند األهداف متعدد التحسين ألداء المحددة التجريبية النماذج استخدام تم )ga (لتعظيم )mrr ( وتقليل )tw .( النتائج أظهرت .المخرجات المثلى على والحصول التجريبية، النماذج صحة من والتحقق اآللي، التشغيل ظروف إلنشاء األمثلية نتائج استخدام تم أدت للحصول على ) ٢٣٫٦٢.amp وشدة التيار ( ، )μs٣٩٬٤٢ النبضة (إطفاء زمن ،)μs١٧٦٫٢٦١النبضة ( تشغيل زمن ان الظروف المثلى: .)g/min٠٫٠٤٥١ ( واقل معدل بليان أداة) g/min٠٫٧٨٣٩١ ( معدل إزالة مواد أعلى al-khwarizmi engineering journal al-khwarizmi engineering journal, vol. 19, no. 4, december, (2023) p. p. 4255 an overview of audio-visual source separation using deep learning noorulhuda mudhafar sulaiman* ahmed al tmeme ** mohammed najah mahdi *** *,** department of information and communications engineering/al-khwarizmi college of engineering/ university of baghdad/ baghdad/ iraq ***adapt centre/ school of computing/ dublin city university/ dublin d09 dxa0/ ireland corresponding author *email: noor.abd2103m@kecbu.uobaghdad.edu.iq **email: asattar@kecbu.uobaghdad.edu.iq ***email: mohammed.mahdi@adaptcentre.ie (received 11 april 2023; accepted 18 june 2023) 3https://doi.org/10.22153/kej.2023.06.00 abstract in this article, the research presents a general overview of deep learning-based avss (audio-visual source separation) systems. avss has achieved exceptional results in a number of areas, including decreasing noise levels, boosting speech recognition, and improving audio quality. the advantages and disadvantages of each deep learning model are discussed throughout the research as it reviews various current experiments on avss. the tcd timit dataset (which contains top-notch audio and video recordings created especially for speech recognition tasks) and the voxceleb dataset (a sizable collection of brief audio-visual clips with human speech) are just a couple of the useful datasets summarized in the paper that can be used to test avss systems. in its basic form, this review aims to highlight the growing importance of avss in improving the quality of audio signals. keywords: audio-visual, source separation, deep learning, cnn, datasets. 1. introduction the process of distinguishing particular audio sources from a mixture of audio signals using visual indicators as further information is known as audio-visual source separation. this method differs from conventional ones that exclusively rely on the audio stream for source separation [15]. in other words, it is a technique that utilizes both auditory and visual information to separate individual sound sources from a mixed audio signal. avss algorithms generally take an input signal containing multiple sound sources and utilize visual information, such as lip movement or facial expressions, to separate the individual sources. the visual information can be captured from various sources, such as video recordings or real-time cameras. the main advantage of audiovisual source separation over traditional audioonly approaches is using visual signals to improve the separation quality. for example, visual cues can help separate speech from background noise [46] or separate multiple speakers in a video recording [16-17]. one advanced method for audio-visual source separation involves the use of deep learning techniques [10-12,14,22,34,37-38]. here are some specific reasons why audio-visual source separation is important: 1-enhancing speech intelligibility: in scenarios where speech is degraded by noise or overlapping sources, audio-visual source separation can be used to isolate the target speaker's voice and improve speech intelligibility [10-12, 17, 20]. 2-improving speech recognition: audio-visual source separation can also improve speech recognition systems' accuracy, by separating out individual speakers and reducing interference mailto:noor.abd2103m@kecbu.uobaghdad.edu.iq mailto:asattar@kecbu.uobaghdad.edu.iq mailto:mohammed.mahdi@adaptcentre.ie https://doi.org/10.22153/kej.2023.06.003 nooralhuda mudhafar sleman al-khwarizmi engineering journal, vol. 19, no. 4, p.p. 4255 (2023) 43 from other sources. in [25] the authors utilized a separation system to separate voices from a mixed audio signal, then fed the separated voices into an automatic speech recognition (asr) system for further processing. in [40] the authors combined the spatial information from a microphone array with visual information from a camera to improve the separation and recognition of multiple speakers in a noisy and reverberant environment. 3-enabling better audio and video processing: audio-visual source separation can be used to separate out different sources of sound in a video recording, which can enable better postprocessing of both the audio and video [23, 28, 47]. overall, audio-visual source separation can help address some of the challenges in speech recognition by improving the quality and intelligibility of speech signals. additionally, the development of audio-visual source separation methods has led to the creation of large-scale datasets that can be used for further research in related fields [17, 50-60]. 2. deep-learning for audio-visual source separation deep learning techniques have emerged as powerful tools in a wide range of applications [69]. deep learning models consist of multiple processing layers that learn different representations of data to solve various problems. the field of audio-visual source separation witnessed the development of various deep learning approaches to help solve the audio separation problem in the presence of visual cues. each approach has its advantages and limitations, depending on the application and data availability. in figure 1, deep learning methods that are commonly used for avss are presented and explained as follows:  deep neural network (dnn): this deep learning architecture consists of multiple hidden layers for data processing. it is widely used for image classification, speech recognition, or natural language processing applications.  convolutional neural network (cnn): this deep learning architecture has the ability to detect patterns in images. it is widely used for image processing and object detection.  long short term memory (lstm): this deep learning architecture can learn long-term dependencies between time-sequenced data. it is widely used for speech recognition and data analysis.  bidirectional long short term memory (blstm): this deep learning architecture can learn long-term dependencies between time sequential data in both backward and forward directions, making it more useful in sequential pattern analysis. deep learning approaches are used to extract audio and visual features and map them to different output signals. one approach is joint audio-visual processing, which processes audio and visual models jointly and uses the output to separate the target audio source, such as in [16, 19, 40]. examples of joint audio-visual processing approaches include cnns and recurrent neural networks (rnns) that input audio and visual data [16]. another approach is the multi-task learning approach, where audio and visual modalities are treated as separate tasks, and a deep neural network is trained to perform both tasks simultaneously. fig. 1. deep-learning methods for audio visual source separation. nooralhuda mudhafar sleman al-khwarizmi engineering journal, vol. 19, no. 4, p.p. 4255 (2023) 44 the pros and cons of the deep learning approach are listed in table 1. it can be observed from table 1 that the pros and cons reflect common observations and considerations in the field. however, it's important to note that variations and specific trade-offs can vary depending on the deep learning architectures, datasets, and problem settings used in different studies. table 1. pros and cons of deep learning approaches pros cons can handle complex and high-dimensional data requires large amounts of data for training can learn complex relationships between audio and visual modalities it can be computationally expensive and require powerful hardware can generalize well to new data can suffer from overfitting to training data can capture both lowlevel and high-level features it may require significant effort for hyperparameter tuning and model selection 3. recent avss works different systems for distinguishing audio-visual inputs have been developed as a result of advancements in deep learning. these systems employ a blend of deep learning techniques, including dnns, cnns, lstms, and blstms. the next part of this section is devoted to categorizing each of these works based on the specific deep learning technique that they use. an organized method for understanding and comparing different approaches to audio-visual source separation is provided by this classification. it also helps evaluate how certain topologies affect separation approaches, which helps to clarify the advantages and disadvantages of each. the dnn-based works will be covered in the subsection that follows. takahashi et al [10] suggested a unique method that included end-to-end speech recognition in order to enhance voice separation performance. a dnn trained on mixed audio signals and their transcriptions is used in the suggested voice separation method, which incorporates end-to-end speech recognition to direct the separation process. the temporal dependencies are modeled and the input signal is converted into a feature representation using deep learning layers like fully connected and lstm. although the technique does not necessitate the pre-separation of audio and visual elements, its effectiveness may be impacted by failures in voice recognition. chung et al. [11] proposed a facefilter approach that enhances speech in a noisy audio recording using a single facial image of the speaker, employing a dnn with three subnetworks that extract and combine visual and audio features to produce a mask for the target speaker's voice. the method is advantageous in scenarios with limited visual data and faster processing times, but may be limited by assumptions of visible and stationary faces, leading to negative impacts on model performance in real-world scenarios, and may not be effective in partially obscured or poor lighting conditions. gu et al. [12] proposed a deep learning-based approach for target speech separation from multimodal and multi-channel mixtures of speech and noise signals using audio, visual, and spatial information to improve accuracy. dnn combines audio spectrogram, visual feature map, and spatial inter-channel phase differences to predict the ideal ratio mask for speech separation, trained end-toend for efficient separation without complex preprocessing. zhang et al. [13] proposed an approach to improve the mvdr beamformer for multichannel target speech separation by replacing the conventional covariance matrix estimation with a dnn trained on a large-scale speech corpus. the approach is more robust for non-stationary noise and acoustic environments. however, the computational cost of training the dnn and computing the mvdr beamformer weights can be high. li et al. [14] proposed an av deep learning approach for multi-channel speech separation by jointly modeling audio-visual cues. it includes a neural network that estimates separation filters for target speech from multiple microphones and video frames, and a multi-task framework for dereverberation and speech recognition. advantage: effective in removing noise and reverberation. disadvantages: requires multichannel audio signals, large amounts of training nooralhuda mudhafar sleman al-khwarizmi engineering journal, vol. 19, no. 4, p.p. 4255 (2023) 45 data, and computational resources for deep neural networks. ong et al. [15] proposed a real-time online multi-source separation method that uses both audio and visual information to estimate the position of speakers and separate target speech from background noise. they developed a deep neural network combining audio and visual processing features. this approach shows improved performance, especially in noisy and reverberant environments. however, it requires multiple microphones and cameras to capture the audio and visual data, and the quality of the separated speech may vary depending on the quality of the captured audio and video. furthermore, in this subsection, the cnn-based works will be discussed. afouras et al. [16] proposed a deep learning model for audio-visual speech enhancement using a two-stream cnn architecture to predict a cleaned audio signal by taking audio and visual inputs. advantages include using both modalities, improving accuracy and outperforming existing models. disadvantages include the requirement for both inputs and the need for a large amount of training data and computational resources. ephrat et al. [17] proposed an audio-visual deep neural network approach for separating multiple speakers in noisy environments. the approach consists of two streams: an audio stream that predicts ideal ratio masks (irm) and a video stream that predicts attention masks to capture the spatial distribution of speakers. these streams are then combined using a multi-modal fusion network to generate the final separated speech signals. the network utilizes cnn and blstm layers to extract meaningful features and model temporal dynamics. an advantage of this approach is its ability to separate speech even when the target speaker is not visible in the camera's field of view. however, it relies on synchronized audio and video data, and its performance may be limited in extremely noisy environments or when multiple speakers are speaking simultaneously. hou et al. [18] proposed deep learning-based audio-visual speech enhancement using cnns for audio and visual processing. the multimodal fusion network combines the two branches to enhance speech intelligibility with lip movements. advantages include handling noisy speech signals and avoiding handcrafted features. however, using lip movements as a visual modality may not be suitable for all scenarios. lu et al. [19] proposed an approach that uses deep neural networks for audio-visual speech separation. the network includes cnn and rnn layers for audio and cnn layers for visual processing. an attention-based multimodal fusion network is estimated by combining the two branches, and estimate the ideal ratio mask for speech separation. the main disadvantage is the need for aligned audio-visual data. zhao et al. [20] proposed an audio-visual source separation method using a cnn. it uses a two-stage approach: first, the cnn predicts the magnitude spectrogram of the target speech signal from visual features; second, the predicted spectrogram is used to estimate the speech signal. visual features are extracted from a pre-trained network and fine-tuned on mixture frames. it can separate speech even in noisy or reverberant environments. however, it requires a large amount of training data. gabbay et al. [21] proposed a method for enhancing speech signals in noisy environments using visual information from a video recording of speakers. they used deep learning to extract facial features from a cnn and integrated them into a deep rnn for speech separation. achieved state-of-the-art performance, but limitations include quality of video, accuracy of facial feature extraction, and computational resources required. gogate et al. [22] proposed a method that uses a cnn to extract visual features and an rnn to process audio signals to estimate a mask separating the speaker's voice from background noise. deep learning improves mask estimation and speech separation. the method is speakerindependent but computationally expensive for real-time use. morrone et al. [23] proposed a method for enhancing speech using audio and visual information in multi-talker environments. the deep neural network architecture includes audio and visual branches, with cnn and rnn in the audio branch and face detection and landmark localization algorithms in the visual branch. the attention mechanism combines the two branches for final results. the disadvantage is that the accuracy of facial landmark detection can affect performance. wu et al. [24] proposed a method to separate speech signals of multiple speakers in an audiovisual recording using deep neural networks. the method jointly learns audio and visual features of the speech signals and performs separation in the time domain. visual features are extracted using cnn and temporal dynamics are modeled using lstm. a deep clustering network is used to fuse audio and visual features. the method preserves the temporal characteristics of speech signals, but nooralhuda mudhafar sleman al-khwarizmi engineering journal, vol. 19, no. 4, p.p. 4255 (2023) 46 may not work well in cases with similar speakers or occlusions in the visual data and may have long processing times. gogate et al. [25] proposed that the dnn model combines binaural cues and visual input to improve the speech quality of unknown speakers in a noisy environment. multi-stream cnn considers the temporal and spatial dynamics of binaural audio and visual lip images to estimate spectral masks for each channel. binaural audio signals preserve spatial information, improving speech separation. disadvantages include the complexity of training due to supervised and unsupervised learning methods. nguyen et al. [26] proposed a method to improve audio-visual sound source separation using object-level priors. they used a deep neural network with convolutional and deconvolutional layers to learn audio and visual features and estimate masks for each sound source. the method involves two stages: object-level localization and object-aware separation. in the first stage, an object detection model is used to localize the sound sources in the video frames. the audio signals are separated in the second stage based on the estimated object locations and their corresponding masks. the advantage is that it can better exploit object-level information and improve separation performance. still, the method relies on an object detection model, which can be challenging in complex scenes with multiple objects or occlusions. li et al. [27] presented a model for extracting speech signals from mixed sound sources in a single-channel recording using both audio and visual data. it makes use of an attention mechanism and is composed of fully connected layers, bidirectional lstm, and cnn. for best results in terms of performance, it may require a large amount of training data and be computationally costly. gu et al. [28] presented a deep learning method that combines audio and visual data to distinguish desirable speech from distracting sources. in order to improve separation performance, the model integrates an optical encoder network for extracting visual information, a cnn for processing audio features, and a multimodal fusion network. utilizing both aural and visual modalities, the method gains a more comprehensive representation of the input signals. multiple microphones can also be used by the model to acquire spatial information and improve separation accuracy. it is important to keep in mind, nevertheless, that this method might need a significant quantity of training data and that using several modalities and channels could result in higher computational complexity. gan et al. [29] proposed an audio-visual source separation approach using a deep neural network that leverages a musician's body movements to separate instruments. two-part model: video analysis network and visual-audio separation network. video analysis extracts keypoint coordinates and global context using contextaware graph cnn to generate latent representation. visual-audio separation uses visual features to separate audio. does not require prior knowledge or training data, but assumes each instrument is associated with specific body movements. the method requires a motion capture system, but it is not practical in real-world scenarios. zhu et al. [30] proposed an audio-visual source separation method consisting of two stages: visual feature extraction and sound source separation. a pre-trained cnn extracts visual features from the input video frames, which are used to compute attention maps for each sound source. a cascaded opponent filter network (cofn) is used for sound source separation, with attention maps guiding the separation process. the approach improves separation performance, but requires a pre-trained cnn and significant computational resources for training. tan et al. [31] proposed a two-stage strategy for speech enhancement that included a separation module for noise reduction and a dereverberation module for room reverberation suppression. a cnn is used in the architecture for audio-visual feature extraction, while a blstm is used for dereverberation. the approach has the benefit of being able to handle weakly labeled data and uses a multimodal fusion layer for feature fusion. however, accuracy depends on the strength of audio-visual connection, which in complicated scenarios may not always be dependable. qu et al. [32] proposed a method for improving speech separation that combines auditory and visual modalities. a cnn is used to retrieve features from both modalities, which are subsequently integrated into a shared embedding space with the help of a multi-modal fusion network. then, using the joint embedding space as a reference, a target speech separation network is trained to extract the target speaker's speech from the mixture. the approach is adaptable and nooralhuda mudhafar sleman al-khwarizmi engineering journal, vol. 19, no. 4, p.p. 4255 (2023) 47 may be applied with a variety of input modalities; however, it may need high-quality video input, which is not always feasible in real-world scenarios. rahman et al. [33] proposed a weakly supervised audio-visual sound source detection and separation method using video-level labels for joint learning of visual and auditory segments. it consists of a video frame semantic segmentation path and a spectrogram mask prediction path implemented using an attention u-net architecture. the final mask is constructed using multi-modal audio-visual features. it can handle multiple sound sources and does not require precise temporal annotations. it has a lower separation performance than fully-supervised methods, and the quality of visual features can affect the separation performance. gao et al. [34] proposed a deep learning approach for audio-visual speech separation. it consists of two networks: an audio network and a visual network, both are cnns. the networks are jointly trained using a cross-modal consistency loss. the approach demonstrates good performance even in challenging scenarios but requires paired audio and video data during training. however, its performance may be limited in cases of significant overlap between speakers or when the speakers are not visible in the video. majumder et al. [35] proposed an audio-visual source separation approach using a robot equipped with a camera and microphones. a deep learning model consisting of cnn predicts each sound source's arrival direction, and the robot moves its head to focus on the desired sources. audio signals are then separated using a deep neural network. the approach allows for real-time audio-visual source separation in dynamic environments but may be disruptive in quiet or crowded spaces. liu et al [36] proposed a two-stage feature fusion approach for audio-visual speech separation. stage one uses a cnn to extract features from both audio and visual modalities, fused using a gated fusion mechanism. stage two uses an rnn to separate mixed speech signals into individual sources. advantages include handling complex scenes and improved performance. disadvantages include dependence on synchronization and increased computational complexity. tian et al. [37] proposed an audio-visual sound source separation approach that uses visual information to separate target sound sources. object candidates are obtained using faster rcnn, and a cyclic co-learning framework jointly optimizes sounding object visual grounding (sovg) and sound separation (ss) tasks. the sovg module uses a pre-trained object detection network to locate the target sounding object and project visual features onto a shared embedding space with audio features. the ss module separates sound sources based on the shared embedding space, and the estimated source is used to update the sovg module for better visual grounding. the approach can handle multiple sound sources but may be limited by the object detection network's accuracy and visual information quality. makishima et al. [38] proposed a deep learning method that utilizes both auditory and visual information to separate speech signals from an audio-visual mixture. it consists of two subnetworks, a visual network and an auditory network, which generate embeddings that are concatenated and passed through a decoder network. the model introduces a cross-modal correspondence loss function to align auditory and visual information and improve performance. one disadvantage of the approach is its high dependency on visual data, making it unreliable when it is limited. nguyen et al. [39] proposed an unsupervised technique based on audio-visual generative modeling for the purpose of speech separation. they used a variational auto-encoder (vae) to learn a variable generative model from clean speech. the model uses visual information (lip movements) associated with each speaker to separate the audio streams through a visual network. the system does not require the clear identification of acoustic signals, but its performance is highly dependent on visual information and has a high computational cost. lee et al. [40] proposed a deep learning modality that uses cnns to extract audio and visual information. the outputs of cnns are then integrated into a joint representation by using a cross-modal affinity function. the target speech signal is reconstructed using the combined representation. the approach relies purely on the connection between the audio and visual signals and does not require prior information of the speakers' speech patterns or microphone placements. one disadvantage of the approach is its high dependency on the strong coupling between audio and visual data input. zhu et al. [41] proposed an object categorybased technique for visual sound source separation. at first, each pixel in the video recording is categorized into a specific item nooralhuda mudhafar sleman al-khwarizmi engineering journal, vol. 19, no. 4, p.p. 4255 (2023) 48 category by using a pre-trained object identification network. the audio stream and item category map are then sent into a neural network, which is trained to perform the separation. the approach can increase separation performance by utilizing object category information but it depends on its availability and can only conduct single-frame separation without taking temporal information into account. gu et al. [42] proposed a deep learning method to estimate beamforming filters for time and frequency domains. the method consists of a frequency-domain beamforming network and a time-domain beamforming network, which enhance the target speech and suppress interfering sources. the approach is more flexible and adaptable to different situations than traditional beamforming methods but requires a two-stage approach, which may increase computational complexity and training time. oya et al. [43] proposed a method for audiovisual source separation that uses bounding boxes as supervision. the method has two stages: object detection to obtain bounding boxes, and a neural network for separation. it does not require manual annotation but relies on the accuracy of the detection model. zhu at al. [44] proposed a method for audiovisual sound source separation and localization using self-supervised motion representations. learns motion features from video data without explicit annotations and incorporates them into a deep neural network for separation and localization. the visual motion pattern of sound sources is used to estimate location. learns motion features with cnn to predict future frames from past frames. it is scalable, efficient, and eliminates the need for manual feature engineering. performance depends on video quality and resolution, which may be limited in real-world applications with low-resolution or noisy videos. pham et al. [45] proposed a novel approach for training a cross-modal retrieval framework using video data. the framework is refined through three loss functions: separation loss, objectconsistency loss, and cross-modal loss. by incorporating visual guidance, this method enhances source separation performance, especially in situations where the audio signal is degraded or the sources are closely positioned. however, it is crucial to remember that this method depends on auditory and visual data, which might not always be available or practical in real-world situations. other authors created a new network architecture for audio-visual source separation that is also based on deep learning: xu et al. [46] proposed a method using a neural network called minus-plus net (mpn) to separate sound sources from mixture signals using audio and visual input. the mpn recursively separates the sources in a coarse-to-fine manner and can handle complex mixtures of sources. the approach has advantages in improved performance and the separation of multiple sources, but relies on pre-segmentation and has longer processing times. zhao et al. [47] proposed a deep learningbased method for audio-visual sound separation using visual motion features. the approach involves two stages: training a motion-to-sound network (mtsn) to map motion features to sound sources, then refining the estimated sources using a sound refinement network (srn) with spectrograms and original audio. the method is flexible and adaptable but may not work well in low-light or noisy environments and can struggle with visually similar or closely located objects. lu et al. [48] proposed an audio-visual method to separate speech signals from a mixture of multiple speakers using a deep neural network architecture called avdc. the avdc network clusters audio and visual features using convolutional and recurrent layers, then applies a clustering algorithm to separate speech signals. the method works with one modality and is computationally expensive, but can separate speech signals in challenging scenarios. gao et al. [49] proposed a method for audiovisual source separation using a co-separation network, which learns to separate sounds from different visual objects by jointly modeling audio and visual features. the approach is real-time and generalizable to different scenarios without prior knowledge of sound sources. still, it requires synchronized audio and video inputs and may degrade in the presence of occlusions or incomplete visual information. table 2 illustrates deep-learning features for avss in terms of complexity, data availability, and other features. nooralhuda mudhafar sleman al-khwarizmi engineering journal, vol. 19, no. 4, p.p. 4255 (2023) 49 table 2. deep learning features for avss feature deep learning-based avss type of model neural networks (cnns, rnns, gans) training data availability require large amounts of labeled data model complexity complex models with high computational requirements performance can achieve state-of-the-art performance on many tasks robustness to noise can handle complex, noisy audio-visual scenes generalization can generalize well to unseen data training time longer training times due to the complexity of the models 4. datasets an audio-visual dataset is a collection of data that includes both audio and visual information. this dataset type is often used in machine learning and computer vision applications where audio and visual features are needed to train a model. audio-visual datasets can include video recordings with accompanying audio tracks or separate audio and visual files that are synchronized to each other. it is important to follow certain techniques and protocols to create a dataset for audio-visual source separation. this includes gathering a diverse range of data, accurately labeling the audio and visual components, preprocessing the signals, dividing the dataset into appropriate subsets, maintaining a balanced distribution of samples, and applying data augmentation techniques. implementing these steps makes the dataset more representative, reliable, and suitable for training and evaluating audio-visual source separation models. table 3 shown below illustrates some of the commonly known datasets. table 3. audio-visual datasets dataset description grid audio-visual speech recognition dataset consisting of 33 speakers uttering 1000 phrases. contains video, audio, and aligned phonemic transcriptions [50]. lombard grid audiovisual lombard speech corpus, freely available for download. it contains 5400 utterances (2700 lombard and 2700 plain reference utterances), produced by 54 talkers [51]. tcd timit designed for continuous audiovisual speech recognition research. consists of high-quality audio and video footage of 62 speakers reading a total of 6913 phonetically rich sentences [52]. ouluvs the ouluvs database includes video and audio data of 20 subjects consisting of 10 phrases [53]. ouluvs2 a multi-view audiovisual database for non-rigid mouth motion analysis. it includes more than 50 speakers uttering three types of utterances [54]. voxceleb an audio-visual dataset consisting of short clips of human speech, extracted from interview videos uploaded to youtube [55]. voxceleb2 contains over 1 million utterances for 6,112 celebrities, extracted from videos uploaded to youtube [56]. lrw consists of up to 1000 utterances of 500 different words, spoken by hundreds of different speakers [57]. lrs consists of thousands of spoken sentences from bbc television. each sentence is up to 100 characters in length [58]. lrs3 consists of thousands of spoken sentences from ted and tedx videos [59]. avaactivespeaker contains about 38.5 hours of face tracks, and the corresponding audio [60]. avspeech large-scale audio-visual dataset comprising speech video clips with no interfering background noises contains roughly 4700 hours of video segments [17]. 5. conclusions the rapid advancement of deep learning approaches has revolutionized the field of audiovisual source separation, enabling significant progress in separating speech and other audio sources from complex audio-visual mixtures. dnns, cnns, lstm, and blstm have emerged as powerful tools to address the challenges posed by audio-visual sources' multi-modality and dynamic nature. researchers should consider the task requirements, available data, model nooralhuda mudhafar sleman al-khwarizmi engineering journal, vol. 19, no. 4, p.p. 4255 (2023) 50 complexity, computational resources, interpretability needs, previous research, and time/resource constraints when choosing a method. through careful evaluation of these factors, researchers can make informed decisions and choose a suitable method. it is important to note that blstm alone may not be sufficient, but it plays a crucial role as a key component in many state-of-the-art architectures. the combination of blstm with other modules like cnns and dnns has demonstrated promising outcomes in enhancing separation performance. thus, the synergistic utilization of these techniques within an integrated system yields the most promising results, rather than relying on any single technique in isolation. moreover, incorporating these models with additional deep learning techniques, such as attention mechanisms and generative adversarial networks, has remarkably improved the separation process. large-scale datasets and the availability of high-performance computing resources have facilitated the training of deep models and the development of more complex architectures that can handle the variability of acoustical conditions. despite these advancements, significant challenges remain, including handling variable speech overlap and room acoustics. there is a need for robust models that can generalize across different acoustic environments and effectively handle various types of audio-visual mixtures. in conclusion, the use of deep learning approaches in audio-visual source separation has enabled significant progress in the field and holds great promise for further 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[60] j. roth et al., "ava active speaker: an audio-visual dataset for active speaker detection," ieee international conference on acoustics, speech and signal processing (icassp), barcelona, spain, 2020, pp. 4492-4496 http://dx.doi.org/10.1109/icassp40776.20 20.9053900. http://dx.doi.org/10.21437/interspeech.2017-950 http://dx.doi.org/10.21437/interspeech.2017-950 http://dx.doi.org/10.21437/interspeech.2018-1929 http://dx.doi.org/10.21437/interspeech.2018-1929 http://dx.doi.org/10.1007/978-3-319-54184-6_6 http://dx.doi.org/10.1007/978-3-319-54184-6_6 http://dx.doi.org/10.1109/cvpr.2017.367 http://dx.doi.org/10.5244/c.31.155 http://dx.doi.org/10.1109/icassp40776.2020.9053900 http://dx.doi.org/10.1109/icassp40776.2020.9053900 (2023) 42-55، صفحة 4، العدد19دجلة الخوارزمي الهندسية المجلم نور الهدى مظفر سليمان 55 نظرة عامة على فصل المصادر السمعية والبصرية باستخدام التعلم العميق محمد نجاح مهدي *** **ميمياحمد الت * نورالهدى مظفر سليمان *,** قسم هندسة المعلومات واالتصاالت/ كلية الهندسة الخوارزمي/ جامعة بغداد / كلية الحاسبات/ جامعة دبلن adaptمركز*** noor.abd2103m@kecbu.uobaghdad.edu.iq:البريد االلكتروني* asattar@kecbu.uobaghdad.edu.iq:البريد االلكتروني** mohammed.mahdi@adaptcentre.ie :البريد االلكتروني*** الخالصة نتمائ avss( القائممة علمى تقنيمات المتعلم العميمق قمق avssأنظمة فصل المصادر السممعية والبصمرية لىلبحث المقدم هنا لمحة عامة عيعطي ا ايا وعيمو استثنائية في عدد من المجاالت ، بما في ذلك تقليل مستويات الضوضاء ، وتعزيز التعرف على الكالم ، وتحسين جودة الصوت تمت مناقشة مز التمي تحتمو tcd timit مجموعمة بيانمات avssكل نموذج من نماذج التعلم العميق خالل البحث يث يقوم بمراجعة مختلف التجار الحالية على مقاطع مجموعة كبيرة من ال voxcelebعلى تسجيالت صوتية ومرئية من الدرجة األولى تم إنشاؤها خصيًصا لمهام التعرف على الكالم( ومجموعة بيانات مجموعات البيانات المفيدة التي تم تلخيصها في هذا البحث و التي يمكن اسمتخدامها الختبمار أنظممة هي ا دكالم البشر ( ة للالسمعية والبصرية المختصر avss الغرض من هذه المراجعة في شكلها األساسي هو تسليط الضوء على األهمية المتزايدة لـ avss ات الصوتية في تحسين جودة اإلشار mailto:noor.abd2103m@kecbu.uobaghdad.edu.iq mailto:asattar@kecbu.uobaghdad.edu.iq mailto:mohammed.mahdi@adaptcentre.ie acknowledgments this is an open access article under the cc by license : al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 21, no. 4, december, (2025), pp. 1331 synthesis and characterization of flash graphene for use in remediation of contaminants in iraqi groundwater using batch adsorption techniques noora subhi raheem1*, and hayder m abdul-hameed2 1,2 department of environmental engineering, college of engineering, baghdad university, baghdad 10071, iraq *corresponding author’s email: nawra.sobhi2311@coeng.uobaghdad.edu.iq (received 16 january 2025; revised 31 may 2025; accepted 3 july 2025; published 1 december 2025) https://doi.org/10.22153/kej.2025.07.001 abstract this research aims to assess the behavior and effectiveness of flash graphene (fg) in the remediation of ph, ec, total dissolved solids (tds), cations, and fe+3 from real groundwater (gw) of the wells of the al-raeed research station, which is used in reclamation and irrigation. enclose that contaminant levels in remediated real gw abide criterion of iraqis and food and agriculture (fao) standards. adsorption technology in the batch adsorption mode experiment was achieved by fg, a carbon-based, highly porous structure that has strong adsorption capacity due to its beneficial surface area (71.7 m2/gm). a locally designed and manufactured electroflash reactor was used to synthesize fg by converting activated carbon derived from banana peels. in this process, banana-peel activated carbon (bpac) was exposed to a mild spark and 8–10 circuit break shocks per reactor run. the fg morphology and functional adsorption groups were characterized via scanning electron microscopy, fourier transform infrared, and x-ray diffraction tests. the remediation efficiencies in the batch experiments were 69%, 69%, 61%, and 100% for ca, mg, tds, and fe, respectively, at an optimum fg dosage of 1.5 g, contact time of 4 hours, 150 rpm, and ph of 7. the adsorption capacity, which followed the freundlich isotherm model, was ca+2 = 14.6 mg/g, mg+2 = 16.4 mg/g, fe+6 = 0.074 mg/g, tds = 7.3 mg/g. finally, with the synthesized fg used and the parameters (dose, agitation speed, ph, and contact time) adjusted, the batch mode experiments on real gw samples yielded ph, ec, t.d.s., mg+2, ca+2, and fe+3 values, which satisfied fao restrictions and iraqi standards. keywords: adsorption; cation; flash graphene; bpac; groundwater; contaminant; synthesize 1. introduction preserving groundwater (gw) is the aim of many authorities and agencies responsible for water issues to keep gw free of contaminants and to preserve the quality of surface water, and subsequently, ecosystems. furthermore, the supply of drinkable water in several nations; this gw may also be employed for industry and agriculture [1], in order that the gw supply for irrigation purposes contributes to agricultural output, productivity, and irrigated crop quality [2]. however, rapid technological development, increased pollution, and climate change have resulted in shortage in water resources and marked reduction in water quality [3]. gw resources are considerably vulnerable to anthropogenic pressures. direct industrial waste disposal contamination, landfill leachate, unintentional toxic material spills, agricultural activities, and overexploitation of aquifers are factors contributing to the depletion of gw resources. these issues pose a threat to human health and the environment [4]; thus, investments in remediation technologies are needed [5]. physical, chemical, and biological technologies have all been employed to restore gw. volatilization, ultrafiltration or filtration, incineration, and adsorption are physical methods mailto:nawra.sobhi2311@coeng.uobaghdad.edu.iq https://doi.org/10.22153/kej.2025.07.001 noora subhi raheem al-khwarizmi engineering journal, vol. 21, no.4, pp. 1331 (2025) 14 for gw treatment [6]. an efficient technique is adsorption. this technique is known for its straightforward design, high efficiency, and adaptability in terms of use [7]. adsorption is less costly and can be executed on site, reducing the possibility of contaminants being transported to depollution sites. this process is a good alternative for the recovery of adsorbed minerals from the adsorbent media [8]. graphene, activated carbon (ac) (made from various types of agricultural wastes), carbon nanotubes, graphene and its derivatives, flash graphene (fg), and other carbon-based adsorbents have been investigated for gw remediation purposes [9]. graphene is a carbon-based system comprising a thin two-dimensional substance, one sheet of graphite crystal, and a flexible bond formation. it is composed of three more carbon atoms hybridized with carbon atoms in a honeycomb structure [10]. two main approaches are used in graphene synthesis: bottom-up and top-down. one technique that is used in the bottom-up approach is the chemical vapor impregnation method [11]. one of the more sophisticated processes is the fg synthesis method, which uses an electric current to flow through the banana peel activated carbon (bpac) powder. this technique transforms amorphous carbon into graphene by utilizing energy and an electrical discharge [12]. fg structure endows several physical/chemical characteristics, making it useful in adsorption technology to remediate contaminants. adsorption effectiveness is substantially determined by the surface area, porous structure, oxygen-containing and other functional groups, adsorption circumstances, and adsorbate characteristics, so as an adsorbent fg synthesis and have been extensively studied and effectiveness in aqueous systems, which are manage and identify contaminants more than air and soil pollution remediation [13]. the chemical and physical properties allowed graphene to be used as an adsorbent according to xu et al. [14]. sufficiently crystalline or free of imperfections, graphene has a chemically inert surface. typically, pure graphene’s surface engages in physical adsorption (π–π interactions) with other molecules. surface flaws and surface functional groups are typically added to graphene surfaces to increase their reactivity. to adjust the surface and electrical characteristics of graphene, for instance, chemical doping with atoms such as b and n and adding functional groups such as carboxyl, carbonyl, and amine groups, when the number of layers is odd, a linear band with ab arrangement will appear in few-layer graphene. intrinsic singlelayer graphene is a zero-gap semiconductor, and its electronic band structure results in electrically conducting and metallic properties. the band structure becomes increasingly complex as the number of layers expands, causing the conduction and valence bands to overlap and many charge carriers to form. fg is used in many sectors, and environmental and health preservation applications. this article discusses the environmental application of fg in the remediation of contaminant concentration [11], the insertion of real gw quality parameter values for ec, ph, major cations (k+, na+, mg+2, ca+2), major anions (cl−1, so4 −2, no3 −1, hco3 −1), and fe+3, and remediation of (ph, ec, t.d.s., cations, fe+3) [15]. wang et al. [16] reported that cr, pb, cd, cu, and hg are the most prevalent heavy metals in contaminated water. they also investigated how cr+6 was removed from aqueous solution using an indirect reduction mechanism with the help of π electrons on the graphene. under the conditions of graphene = 1 g/l, [cr+6] = 1000 μg/l, and ph 7, the graphene showed a quick removal of cr+6 from the contaminated water with a high removal efficiency and full removal of cr+6 within 5 minutes. graphene generally exhibits a high adsorption capacity on cationic metals and can be used for the adsorption of cationic and anionic metals. high cation values in gw might raise the ph of the soil, causing it to become salty, and the ion exchange events brought on by enriched water, such as the adsorption of na+ and the release of ca+2 and mg+2, cause soil aggregates to scatter and decrease in permeability. it has a high concentration impact on the physical characteristics of soil (deterioration of soil structure) [17]. high consumption can cause neurological disorders, renal difficulties, and stomach and duodenal ulcers [18]. excess salt causes plants to wilt because it raises the osmotic pressure of the soil solution [19]. gw salinity is an issue anywhere in the world because it puts human health at risk, reduces agricultural yield and profitability, deteriorates arable land, raises the price of maintaining infrastructure, and alters or destroys ecosystems [20]. single-step synthesis method of fg, one technique, which is adsorption in batch adsorption mode, developed to improve previous research to remediate the contaminants in real ground water [21]. the green synthesis of graphene sand hybrid (gsh) uses a sustainable carbon source derived from the pyrolysis of low-quality dates, without any negative effects on the environment. this material noora subhi raheem al-khwarizmi engineering journal, vol. 21, no.4, pp. 1331 (2025) 15 is designed to remedy pb(ii)and tc-contaminated gw, and adsorption technology is adopted to bring the experimental results into practice. the sand was combined with the date juice, heated in an oven at 80 °c until solidified on the sand surfaces, and then placed in furnace and transferred to an n2 carbonized furnace at the rate of 100 ml/min. heating was progressively conducted to 750 °c for complete graphitization of the date syrup, and the mixture was heated gradually to 10 °c for 0.5 h at a rate of 2.5 °c/min, then to 200 °c at a rate of 3.3 °c/min, and finally to 750 °c at a rate of 9.1 °c/ min for 3 h. the resultant carbonaceous and graphenelike substance was termed graphene–sand hybrid (gsh), then the experimental work conducted with the optimal batch conditions for contaminant removal (initial ph, contact time, agitation speed, gsh dosage, and initial concentration) was determined. different values of ph (tc, ph 2 to 12; pb[ii] ph 2 to 7) and dosages (0.05–1 g/100 ml) were used within a time span of 0–180 min, with different initial concentrations of the contaminants (co, 50–250 mg/l), this research demonstrated that parameters in the batch mode that influenced the removal of pb(ii) and tc by the effective values of these parameters ( 90 min, 6, 200 rpm, 50 mg/l, and 0.5 and 0.7 g/50 ml/min). the results evidenced by adsorption isotherms (freundlich and langmuir models) and kinetic models, that the langmuir model is seen to fit well and adequately represent the sorption process, and the pseudosecond-order models show a better fit for the experimental data, with a maximum adsorption capacity of 55.4 mg/g and 46.4 mg/g for pb(ii) and tc, respectively the current research, at which the maximum removal efficiency of pb(ii) (98%) and tc (97%), was noted. 2. experimental work 2.1. raw materials the experiment focused on irrigation and land reclamation using remedied genuine gw. genuine gw samples were sourced from wells near the alraeed research station. among the many branches of iraq’s water resources ministry is the al-raeed research station, which focuses on cutting-edge field irrigation research and development. the station, research facility, and reclaimed farmland cover 64 acres at abu-ghareeb, which lies 20 km west of baghdad. gw from the wells was placed in a sterile 2 l glass container; the water was continuously pumped for 3 h. all initial tests were conducted within 48 h. once transported to the station laboratory, the samples were stored in a dark, refrigerated container. according to table 1, samples of gw collected from the al-raeed station were first tested for cations, tds, ph, ec, and fe levels in the laboratory at the station. the gw composition of other cations, anions, heavy metals is listed in the table. standards for irrigation water set by the food and agriculture organization (fao) and those of the iraqi river preservation system were then used to compare the outcomes. the national center for water resources management conducted a batch adsorption experiment to remediate all laboratory tests (cations, tds, ph, ec, and fe) for gw samples treated with fg. table 1, real gw premier values of cations, t.d.s., ph, ec, and fe from al-raeed station gw samples from al-raeed research station iraqi’s standards standards of fao’s limits contaminant contaminant values t.d.s. mg/l 5390 2000 2000 ca mg/l 130 mg mg/l 200 100 ph 8 6.5-8.4 6.5-8.4 ec ds/m 3.8 2 3 fe mg/l 0.618 5 5 cr mg/l 0.04 0.1 0.1 k mg/l 15.5 2 na mg/l 1200 920 cl mg/l 990 350 250 so4 mg/l 1321 400 200 no3 10.1 10 10 hco3 750 610 co3 0 3 noora subhi raheem al-khwarizmi engineering journal, vol. 21, no.4, pp. 1331 (2025) 16 2.2. materials the materials used in the batch adsorption mode experiment to remediate real gw samples included acetic acid (ch3cooh) of 60.052 gm/mol molecular weight, sodium hydroxide (naoh) of 39.99 gm/mol molecular weight, and locally collected agricultural waste, i.e., banana peels. 2.3. equipment the types of equipment used for preparing the bpac and the fg in batch adsorption mode are listed in table 2. table 2, types of equipment name company electrical balance precisa 205°, switzer land ph meter probe china shaker julabo labortechnik gmbh, germany furnace saftherm, china electrical reactor locally manufactured glasswares china conical china pipette china 2.4. characterization of the adsorbent (flash graphene) various techniques were used to characterize fg: 2.4.1. scanning electron microscopy (sem) and energy dispersive x-ray spectroscopy sem micrographs show the nanoflowers’ morphology, the graphene distribution, and the composite’s overall structure, demonstrating the material microstructure and surface morphology [22]. energy dispersive x-ray spectroscopy is an effective method for determining the chemical structure of graphene and its derived compounds [23] . 2.4.2. x-ray diffraction the xrd patterns for fg were first investigated to characterize the structural properties (height, diameter, and number of layers) and to characterize the graphene stacking nanostructures, exhibited composites, and crystallographic structure [24]. 2.4.3. ft-ir spectroscopy graphene stacking nanostructures can be described using this method, which also provides details on their crystallographic structure, stack height, stack diameter, and stack number [25]. 2.5.synthesis of bpac figure 1 shows the banana peels gathered from household garbage. the banana peels were rinsed with distilled water to remove any surface dirt and sun-dried for 3 days [26]. then, the peels were cut into small pieces that measured 2 × 2 mm. to transform the banana peels into ac, they were physically treated through a pyrolysis process (carbonization and activation) for 2 h in a 250 °c furnace. the activation process is normally conducted in the presence of a suitable oxidizing agent, such as steam, for steam carbon dioxide is used, such modification of physical activation technique employing a novel basic media approach to generate ac with a high surface area and controlled pore structure, then passes n2 gas, nitrogen adsorption is employed to verify the effect of the pore structure on the adsorption properties, the process improve the carbon content, usually up to between 85% and 95% [27]. physical activation is accomplished by using 1 liter per minute of co2 and 1 one liter per minute of n2 for 1 hour for each gas passage, as illustrated in figure 1. the final amount of ac obtained from banana peels was 30 g. figure 2 shows a flowchart representing bpac synthesis. the bpac was ground into a powder with a mixer grinder until it reached a particle size of 0.25 mm, as shown in figure 1. following cooling to ambient temperature, the carbonized samples underwent rinsing with distilled water, several filtration processes, and subsequent drying in a scorching oven set at 110 °c. noora subhi raheem al-khwarizmi engineering journal, vol. 21, no.4, pp. 1331 (2025) 17 fig. 1. bpac synthesized sample of banana peel, dried bp, ac and crushed ac characteristics of the bp, ac, and fg testing results are given in table 3. data were acquired from the ministry of oil and the petroleum development and research center’s lab. table 3, characteristics of the raw material, local adsorbent, and adsorbent 2.6. synthetization of adsorbent (fg) batch mode adsorption was conducted to remediate cations, tds, ph, ec, and fe in gw, with varying premier concentration values. laboratory analysis confirmed that the real gw premier pollutant concentration complied with iraqi standards for irrigation use. a valuable agricultural waste product, fg was created from bpac. synthesizing the adsorbent for contaminants in gw sample cleanup, fg requires crushing ac into powder and then using the powdered bpac to make fg. 2.7. flash graphene synthesization method an electrical flash reactor is an equipment that consists of two electrodes of high-voltage electricity connected to a copper wire placed in a pyrex tube, the bpac is placed also in the tube surrounding the wire, the electrical reactor is used to produce the fg from crushed bpac by using the spark of light in the reactor to convert the ac to graphene [28]. the energy required to convert an amorphous carbon feedstock to 1 g of fg has been previously reported as 7.2-23 kj, based on the input feedstock type [29], [30]. the electrical flash reactor shown in figure 2 comprises an electrical source, and the power source is connected to the capacitor cabinet via a circuit breaker cb1. a 220 v ac, 10 circuit breaker is also included with the power supply to provide on/off control; building separate capacitor banks is feasible. two copper electrodes attached to flexible output cables are connected to a plumb line; once the designed voltage is achieved across the capacitors, the charge can be released to accomplish the whole closed electrical circle. [31] properties banana peels activated carbon flash graphene surface area, m2/g 0.5519 0.5415 71.7 bulk density gm/cm3 0.4905 0.4412 0.4333 real densities, gm.cm−3 1.4442 1.3902 1..335 noora subhi raheem al-khwarizmi engineering journal, vol. 21, no.4, pp. 1331 (2025) 18 cb1 is the power source to charge capacitors and control the spark intensity and for led luminaires utilized as indicators of instrument charge and status [32]. it provides the system with the voltage required to charge a high-voltage capacitor (460 × 4) via a resistor. the bpac of the 5 g sample (figure 3) is placed between two plug electrodes that were further contacted by copper electrodes. an electrical pulse is then discharged through the sample. this pulse causes carbon–carbon bonds to break and rearrange into high-quality graphene [33]. the discharge duration was entered as 2-4 seconds between each spark of light, achieved manually through breaking the circuit eight to 10 times and blowing on the switch [34]. after the capacitor is charged, cb1 is switched off, leaving the bank charged and prepared for release. capacitors are stored in a capacitor bank and operated by a solid-state relay. the capacitor banks are coupled to the kill switch, which is upstream from the sample holder connection. to slow the current and provide more steady electrical control, an inductor is connected in series with the circuit [29]. figure 4 explains the sample of fg. fig. 2. electrical flash reactor fig. 3. synthesized fg flashlight spark fig. 4. sample of flash graphene. noora subhi raheem al-khwarizmi engineering journal, vol. 21, no.4, pp. 1331 (2025) 19 3. adsorption experiments 3.1. batch mode experiment analysis of the fg’s adsorption capacity was conducted on cations, tds, ph, ec, and fe+3 pollutants in the gw samples to determine the remediation efficacy of this test on real gw. with one parameter fixed and the others validated, four experiments were performed on the affected parameters (dosage, ph, time, and rpm), as shown in table 4. the test operation is applied using the given parameter settings, then the optimal performance is selected. the original gw samples are processed for the lowest contaminant concentration using these operation conditions, which are based on previous scientific research of adsorption studies. table 4, experiment conditions of adsorption, batch mode variables parameters values constant parameters dosage (g) 0.5, 1, 1.5, 2, 2.5, 3 2 h, 200 rpm, ph 7 ph 5, 7, 10 2 h, 1.5 g, 200 rpm contact time (h) 1, 2, 3, 4 1.5 g, 200 rpm, ph 7 agitation speed (rpm) 100, 150, 200, 250 2 h, 1.5 g, ph 7 3.1.1. fg dose for each set of adsorption tests, six conical flasks containing 100 ml of gw were filled with varying amounts of fg sorbent. the flasks were then subjected to contact time, agitation speed, and ph values while being kept at a temperature of 25 °c. for 2 h at 200 rpm, six flasks containing 100 ml of gw sample were mixed with weighted adsorbent of 0.5, 1, 1.5, 2, 2.5, and 3 g, similar to table 5. table 6 shows the experiment's remedial outcomes. table 5, fg dosage experiment adsorbent dosage g ph contact time h agitation speed rpm flash graphene 0.5 7 2 200 1 1.5 2 2.5 3 table 6 cations, tds, and fe+3 conc., ph, and ec values in the dosage experiment results dosage of adsorbent (g) pollutant values ec ds/m ph t.d.s. mg/l ca+2 mg/l mg+2 mg/l fe+3 mg/l 0.5 4.26 8.65 2726 88 187 0.0766 1 4.94 8.48 3458 40 170 0.1333 1.5 3.35 8.52 2144 120 120 0.2085 2 6.41 8.4 4487 88 187 0.293 2.5 7 8.43 4900 32 170 0.455 3 7.8 8.52 5460 32 197 0.5696 noora subhi raheem al-khwarizmi engineering journal, vol. 21, no.4, pp. 1331 (2025) 20 3.1.2. agitation speed (rpm) batch mode adsorption experiments rely on the agitation speed experiment to find the best speed for remediating the contaminant concentrations and keeping the experiment time to a minimum. without this experiment, the experiments could take longer. gw samples with fg dosages of 1.5 gm/100 ml of real gw, ph values of 7 and (2) hours, respectively. at speeds of 100, 150, 200, and 250 rpm, measured the duration that each sample came into touch with the agitation. for a variety of rpm values, table 7 lists the data of each adsorption experiment. table 7, cations, tds, ph, ec, and fe+3 with different agitation speed levels. 3.1.3. contact time each of the four conical flasks containing 100 ml of gw was filled with 1.5 g of fg as part of the remediation batch mode experiment by adsorption to determine the optimum time to remediate the gw sample. afterward, the flasks of 100 ml of real gw were stored in a shaker and vibrated at room temperature with ph = 7 and 150 rpm. four distinct times (1, 2, 3, and 4 h) were used to prepare the four samples with consistent parameters (rpm, ph, and dose). each conical flask is shown in table 8. table 8, cations, tds, fe conc., ph, ec values with different periods of contact times contact time (h) pollutant values ec ds/m ph t.d.s. mg/l ca+2 mg/l mg+2 mg/l fe+3 mg/l 1 3.66 7.47 2342 144 46 0.123 2 3.35 7.16 2144 96 62 0.1053 3 5.51 7.96 3857 216 19 0.1095 4 3.48 7.29 2227 40 89 0 3.1.4. impact of ph of the solution a 1.5 g sample of fg adsorbent was added to three 100 ml genuine gw samples. the ph values of the samples were confirmed to be 5, 7, and 10, and measurements were made for the solutions’ preparation, contact time (4 h), and rotational speed (150 rpm) for each of the three conical flasks. table 9 shows the amounts of sodium hydroxide (naoh) and acetic acid (ch3cooh) that were added to the flasks to maintain the various ph values. the results are also shown in figures 8 (a– d). table 9, ec value, cations, tds, fe concentrations for different ph values ph pollutant values ec ds/m t.d.s. mg/l ca+2 mg/l mg+2 mg/l fe+3 mg/l 5 5.72 4004 355 56 0 7 3.47 2221 72 120 0 10 3.63 2323 56 106 0.3391 (rpm) pollutant values ec ds/m ph t.d.s. mg/l ca+2 mg/l mg+2 mg/l fe+3 mg/l 100 5.1 8.3 3570 144 43 0.182 150 3.72 7.96 2381 96 62 0.1053 200 3.35 8.52 2144 120 120 0.2085 250 5.72 8.72 4004 355 56 0.3391 noora subhi raheem al-khwarizmi engineering journal, vol. 21, no.4, pp. 1331 (2025) 21 3.2. adsorption isotherm models explains the connection between the concentration of a substance in the equilibrium solution at a constant temperature and the quantity of solute adsorbed [35] 3.2.1. langmuir isotherm the adsorptive capacity of different adsorbents is measured and compared using langmuir adsorption, which was initially developed to characterize solid–solid phase adsorption. the langmuir isotherm balances the corresponding adsorption and desorption rates [36]. the linear form of the langmuir equation is ce/qe=(1/(qm×kl)) +(ce/qm), …(1) where ce is the adsorbate’s concentration at equilibrium (mg/l), qmax is the quantity of molecules adsorbed on the adsorbent’s surface at any time, and maximum adsorption capacity (mg/g) and kl langmuir constant (l/mg). 3.2.2. freundlich isotherm hardly a large variety of adsorption values may be used with this adsorption isotherm model. plotting log qe versus log ce yields a straight line with 1/n as the slope and log (kf) as an intercept, indicating the variables of this isotherm model [37]. the nonlinearized form is qe = kf ce×1/n. … (2) the linearized form is log qe =log kf + (1/n× log ce). ... (3) 4. results and discussion 4.1. adsorption fg has the potential to be a valuable tool in batch adsorption techniques for decreasing real gw pollutants due to its exceptional features, including its light weight, high flexibility, chemical stability, huge specific area, and robust tensile strength. the vast majority of these composites’ possible applications are in electrical or catalytic reactions, as mentioned in [9]. environmental remediation is a frequently used and important application of bulk carbon [38]. the capacity of a solute to adsorb onto an adsorbent is heavily dependent on two primary parameters: surface chemistry and pore density. ion exchange, hydrogen bonds, electrostatic bonds, van der waals forces, and countless other types of bonds can be formed when particles with opposite charges engage with one another [39]. the π electrons of the carbocyclic six-membered ring were found to aid in the indirect reduction process of iron from an aqueous solution. gw also includes trace amounts of inorganic cations such as magnesium and calcium. given the high amounts of these cations in the original gw, any contamination must be removed. cations were adsorbed onto graphene due to their positive charge [40]. according to the test results, cations (ca+2, mg+2), tds, ph, ec, and iron (fe+3) were all revived in the gw samples. using a 1.5 gm/100 ml gw sample of fg for 4 h, adsorption batch mode tests were performed to investigate the critical parameters for pollutant adsorption onto the adsorbent. fg was made from bpac. according to table 8, the solution has a ph of 7 when spun at 150 rpm. 4.2. flash graphene characterization 4.2.1. sem and edx the adsorbents’ defined, rough, and exceedingly porous surface morphologies are demonstrated in figure 9, indicating their suitability for adsorption [41]. it demonstrates that graphitic nanoparticles can initiate the nucleation and growth of graphitic crystals by creating a bed for them. when the sem pictures of fg in (a) and (b) are combined, a continuous graphitic shell is eventually produced [42]. for this study, when analyzed fg using sem. its structure is rife with creases and flaws, and its outer layer is noticeably thicker than the rest. in figure 6, fg sheets represent representative shots of sem; between hundreds of nanometers to many microns, the sheet size varies considerably. when exfoliated to single-atom thicknesses using a detergent, these vast sheets may produce an enormous aspect ratio, which has a considerable effect on the characteristics of the resultant nanocomposite to enhance the adsorption capacity of fg [34]. the edx spectra were collected from the lateral size (~1000 μm2) area of fg on the substrate, taken with the electron beam energy of 20 kev. the synthesis stage of fg produces a large external surface with sufficient pores [43]. results of the edx spectrum show the presence of elemental contents of c, o, si, p, k, cl, ca, n (wt.%), respectively for fg samples of 45.68%, 35.93%, 1.32%, 1.07%, 10.6%, 5.4%, 11.89%, 7.2%, as shown in figure 5. noora subhi raheem al-khwarizmi engineering journal, vol. 21, no.4, pp. 1331 (2025) 22 fig. 5. edx spectrum analysis of fg (a) (b) fig. 6. flash graphene sem micrographs (a) spherical particulate seeds (b) fg layers shells developed upon seeds 4.2.2. xrd the commercial (raw) graphite’s xrd spectra, which showed an average particle size (d50) of 111 mm. with a d-spacing (interlayer spacing) of 3.36 å in, the distinct characteristic sharp peak for graphite appears at 2q ~ 26º. the intense xrd peaks show that the material is extremely crystalline and that the size reduction is unaffected by the crystalline structure of graphite. graphite’s crystal size, as determined by the scherrer equation with the (002) plane in mind, is 37.5 nm [44]. figure 6 displays the synthesized graphene’s xrd. fg is between the crystalline and amorphous forms of structure, which increases the adsorption capacity. this increase is demonstrated by the appearance of the diffraction line with the high peak at 2θ and the weak (001) peak at 28.5° and 40.7° in the 2θ values [45], which suggest statically supported graphene. which shows the separation between graphene layers and implies statically stabilized graphene. a two-dimensional structure incompatible with layers by translation or rotation, and with the interlayer spacing, which defines statically supported graphite. that of crystalline graphene (0.335 nm) is comparable. figure 7 shows a large peak at a 2θ = 13° [24]. noora subhi raheem al-khwarizmi engineering journal, vol. 21, no.4, pp. 1331 (2025) 23 fig. 7. x-ray diffraction (xrd) 4.2.3. ftir figure 8 shows the graphene ftir spectra. the reflectance mode was used to capture the ftir spectra inside the 4500–600 cm−1 spectral region at a resolution of 4 cm−1. the chemical functionalities that caused the adsorption were located in the 1600– 1400 cm−1 range. carbonyl (c=o), the polyacrylamide molecule (c-h) at 891 cm−1, and the hydroxyl group at 3000 cm−1 are all potential contributors to the 2300 cm−1 peak. the vibrations of the fg structure are amplified by these clusters. a broad band in the stretching vibrations of the hydroxyl group, which can be oh from carboxylic groups, correspond to the hydrogen-bonded oh groups of dimeric cooh groups and intramolecular bound o-h stretching. these –oh and –cooh group on the surface make graphene become negatively charged when they are dispersed in water, allowing them to form electrostatic bonds with poly cations [46]. it occurs between about 3800 and 3200 cm−1, which is an example of functional groups displayed in the structure. the fg ftir spectra reveal the presence of several chemicals that are produced from oxygen. adsorption can only take place when these functional groups coordinate their efforts [47]. simple alkyl-substituted anhydrides (−coor) and stretching in carboxylic acids (−cooh) generally give bands near 1970 and 1788 cm−1, denoted to carbonyl groups (c=o). vibrations of three bands can be identified at 1630 cm−1, unconjugated carbonyl (c=o), and 1593 cm−1 imine (c=c). the symmetric stretching of the c-o bonds in coo− seems to be responsible for the peak at 1386.92 cm−1. one can see a broad band at 1055.97 cm−1. possible causes include of c-o bonds. not only are these little peaks unique to cellulose, but so is the peak (648.34–580.93) cm−1, which could be caused by out-of-phase ring stretching [48]. following the incubation of cations, the fg ftir spectra essentially retain the same throughout the process. the primary reason for the difference spectrum’s negative band around 1600 cm-1 is a reduction in the level of trapped water. some c–o functional groups may be in charge of the cations’ adsorption of fg at low ph, as evidenced by a minor increase in intensity of the band centered at 1055 cm−1, which corresponds to the cations+ associated c–o stretching. such stretching mode of tertiary or aromatic alcohols, such as phenol, may begin to deprotonate and participate in the adsorption of cations because fg is known to have a substantial number of phenol and hydroxyl groups attached to the basal plane [49]. possibly, the 1-methyl-2-pyrrolidinone treatment added ch2 and c-n groups to the graphene surface, causing the bands at 1410 and 1102 cm−1. hydrogen peroxide and sulfuric acid, an oxidation reagent, promote the stretching of amidetype c-o bond, which causes the band at 1631 cm−1. attached to the band at 2925 cm−1 is ch3 stretching groups from the organic solvent of 1-methyl-2pyrrolidinone. c-h bending is reflected by the 795 cm−1 band and the n-h bending by the 643 cm−1 band.[38]. a structural change is induced by the matching functional groups as the peak displacement decreases. the gw pollutants, including cations, tds, ph, ec, and fe+3, have been adsorbed, as indicated by this change. thus, the hydroxyl and carbonyl groups are crucial for the adsorption of the ions because their loading bands shifted to lower displacement. cations may move through the fg and engage with the negatively charged carboxyl and hydroxyl groups on the surface of the nanosheets. the zeta potential of fg is normally 30 mv in bulk water at neutral ph. given their more considerable contact with fg surface groups, divalent ions are also good cross-linkers across arranged sheets, as demonstrated by the formation constant (stability constant) for cations+ complexes with ligands that include carboxylic moieties [50]. noora subhi raheem al-khwarizmi engineering journal, vol. 21, no.4, pp. 1331 (2025) 24 fig. 8. ftir of flash graphene 4.3. remediation of real gw for irrigation and reclamation purposes when compared to iraqi and fao standards, the actual site wells’ gw that were first evaluated fell into the categories of moderate and inappropriate levels for gw (cations and fe) and inappropriate levels for gw (tds) for irrigation and reclamation purposes. as a result, using untreated gw for irrigation harms crops and lowers output. the results of adsorption batch mode experiments at optimum parameters measured and based on the lowest concentrations of the contaminant (cations, tds, ph, ec, and fe) that are reached to 0 mg/l of fe which demonstrate that at high level for any other case of contamination with fe could be remediate to match standards, when compared to iraqi and fao’s limitations, illustrate that the benefits of employing fg as an adequate adsorbent in one of the gw remediation techniques to reduce crop and production damage can be validated using the gw that was remediated by this lab experiment. 4.4. impact of batch experiment parameters 4.4.1. impact of fg dosage an increase in the adsorbent dosage increases the quantity of cations, fe+3, tds eliminated. this spike can be connected to the increasing quantity of active sites for fg that are accessible when the dose is raised. the fg dose value of 1.5 g/100l of real gw produced the best removal value. additional dosage did not lead to improvement, which can be explained to the overlaying of particles. figures 9 (a–d) provide a graphic representation of the experimental results [47]. (a) tds mg/l conc. and dosages (gm) (b) ph & ec ds/m values and dosages (gm) (c) ca+2 and mg+2 mg/l conc. and dosages (gm) noora subhi raheem al-khwarizmi engineering journal, vol. 21, no.4, pp. 1331 (2025) 25 (d) fe+3 mg/l conc. and dosages (gm) fig. 9. impact of different dosages of fg used 4.4.2. impact of agitation speed an agitation speed of 100, 150, 200, and 250 rpm affects fg’s adsorption of cations, fe+3, and tds. the plot indicates that an increased agitation speed resulted in an increased adsorption by fg and the optimum contaminants at 150 rpm. the cause was that when the ca+2, fe+3, and tds ions navigate the boundary layer and approach the solid phase, they come against resistance at the liquid phase. however, for ca+2 ions, optimum agitation speed at 200 rpm, where at the boundary layer dropped as a result of the mixture's increased agitation, which reduced resistance in the liquid phase and the adsorbent's capacity to absorb impurities [51]. figures 10 (a, b, c, and d) depict the experiment’s results. (a) tds (mg/l) values and agitation speed (rpm) (b) ec ds/m and ph values and agitation speed (rpm) (c) ca+2 & mg+2 (mg/l) conc. and agitation speed (rpm) (d) fe+3 (mg/l) conc. and agitation speed (rpm) fig. 10. impact of different rpm levels 4.4.3. impact of contact time the adsorption of ca+2, fe+3, and tds, which is the ideal adsorption time at 3 hours, decreases as a result of the decrease in adsorption sites and concentration gradient. the increase in the pace of adsorption after 3 h may be attributed to the fact that initially, all adsorbent fg sites are empty and the concentration gradient is high. then, it became at maximum uptake on the fg surface [52]. these fundamentals represented in figure 11. (a, b, c, and d) (a) tds mg/l conc. and contact time (h) noora subhi raheem al-khwarizmi engineering journal, vol. 21, no.4, pp. 1331 (2025) 26 (b) ec ds/m and ph values and contact time (h) (c) ca+2 & mg+2 mg/l conc. and contact time(h) (d) fe+3 mg/l conc. and contact time (h) fig. 11. impact of variable periods of contact time. 4.4.4. impact of ph levels due to the high concentration of h+ ions at low and modirate ph levels, which neutralize the negatively charged hydroxyl group (oh-) on the adsorbed surface and reduce the resistance to the diffusion of ions, a higher adsorption capacity occurred at lower ph levels, with an optimal range of ph = 5 and ph=7 for mg+2 ion. the concentration of oh ions at higher ph levels at ph=10 may make it feasible for adsorption to decrease because they raise the resistance ion transport [53]. as it represented in figure 12. (a) t.d.s. mg/l conc. and ph levels (b) ec ds/m value and ph levels (c) ca+2 & mg+2 mg/l conc. and ph levels fig. 12. impact of variable ph levels 4.5. langmuir and freundlich isotherms 4.5.1. langmuir adsorption it includes four preconceptions. (1) the surface of the adsorbent is homogenous, and practically every binding site is identical to one another. (2) the molecules that are adsorbed do not come into contact with one another. (3) the adsorption process is equivalent. (4) maximum monolayer adsorption [36]. noora subhi raheem al-khwarizmi engineering journal, vol. 21, no.4, pp. 1331 (2025) 27 4.5.2. freundlich adsorption it applies to heterogeneous and multilayer molecule adsorption and explains the surface’s heterogeneity and the active site’s exponential distribution and energy [54]. parameters of both adsorption models (langmuir & freundlich) fitting the data of adsorption equilibrium listed in table 9. table 9, langmuir, freundlich model parameters of adsorption capacity for cations and tds. adsorption isotherm parameter ca+2 mg+2 fe+3 tds langumir model qmax 14.6 16.4 0.0074 7.6 kl 0.054 0.0089 12.6 0.004 r2 0.82 0.22 0.33 0.56 frendeulich model 1/n 0.86 0.205 0.883 0.312 kf 0.16 0.0089 0.132 0.001 r2 0.95 0.72 0.63 0.88 the freundlich isotherm in the experimental data exposes fitting better than langmuir, as the value of r2, freundlich > r2 langmuir, indicating that adsorption of cations, tds, and fe+3 is chemisorption with multilayer sorbents at a heterogeneous surface of fg. 4.6. environmental impact this process creates fg from various carbonaceous solid wastes. approximately 2 billion tons/year of municipal solid waste is produced worldwide, which is increasingly out of control. recycling, composting, anaerobic digestion, incineration, gasification, pyrolysis, and landfill disposal are some of the waste management techniques. however, landfills or open dumps end up receiving around 70% of the world’s trash. therefore, a technology that can reduce the amount of garbage or turn waste into useful substance is needed. waste volume is reduced, and fg is produced as a result of the electroflash reactor’s thermal treatment process [55]. the detrimental effect of biomass-based fg synthesis technologies on climate change ranges from 2.73 g to 11.5 g co2e per g of fg generated. these calculations consider the fossil fuel offset from the usage of biogas obtained from the electroflash reactor operations and the carbon captured in the fg. the impact of graphene generated by conventional methods on climate change is far greater than these (149–407 g co2e at the lab scale and 28–407 g co2e at the commercial scale, respectively). this result is mostly due to the fact that electroflash reactor methods utilize considerably less power and chemicals [56] [4]. 5. conclusion the electroflash reactor method for producing fg can be used to transform waste into high-quality turbostratic graphene. this method’s compatibility with various carbon precursors eliminates the need for chemical pretreating, buffer gases, substrates, or graphene washing, demonstrating its enormous potential as a scalable and economically viable synthesis method. one way to improve the environmental benefits of employing agricultural waste is to scale up the process of making flash fg from various carbonaceous sources and to focus on refining the process parameters. the fg adsorption batch experiment aimed to determine if graphene could remove anions, cations, and heavy metals and to remediate ph, tds, and ec for gw’s agricultural and reclamation applications. the optimum conditions in batch adsorption experiments to remediate real gw are as follows: dosage of fg = 1.5 g, contact time = 4 h, agitation speed = 150 rpm, and ph = 7. these conditions result in a remediation efficiency of 69%, 69%, 61%, 100% for ca, mg, tds, and fe, respectively. the adsorption capacities of fg (maximum capacity) at batch adsorption mode experiments, which followed the freundlich isotherm model, are ca+2 = 14.6 mg/g, mg+2 = 16.4 mg/g, fe+6 = 0.074 mg/g, tds = 7.3 mg/g), graphene is a multipurpose material with many potential uses. in the future, researchers may investigate its potential as a water filter for purposes other than drinking and industrial processes. noora subhi raheem al-khwarizmi engineering journal, vol. 21, no.4, pp. 1331 (2025) 28 future research might incorporate more variables that improve gw and wastewater remediation processes, such as irrigation-related parameters (e.g., temperature and new ph level values), and other pollutants. more extensive consideration of the ecological effects of graphene synthesis is required. graphene, a crystalline aggregation of graphite that occurs naturally, is abundant in coal. researchers in academia and industry should focus more on investigating the retention and degradation of graphene manufacturing on a bigger scale as its use grows. greek letters µm micrometer π pi subscripts ac activated carbon ac alternating current pbac banana peel activated carbon cb1 circuit break 1 fao food and agriculture organization fg flash graphene ftir fourier transform infrared spectroscopy gw groundwater led light-emitting diode ppm parts per million rpm revolution per minute sem scanner electron microscopy t.d.s. total dissolved solids v volte xrd x-ray diffraction nm nanometer acknowledgements the national centre for water resources management, an agency of the iraqi water 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[56] c. jia, et al., “graphene environmental footprint greatly reduced when derived from biomass waste via flash joule heating,” one earth, vol. 5, no. 12, pp. 1394–1403, 2022. noora subhi raheem al-khwarizmi engineering journal, vol. 21, no.4, pp. 1331 (2025) 31 رافين الوميضي المستخدم لتقليل الملوثات في المياه الجوفية جتصنيع وتصنيف ال نورة صبحي رحيم1*، حيدر محمد عبدالحميد2 قسم الهندسة البيئية، كلية الهندسة، جامعة بغداد، بغداد 1،2 nawra.sobhi2311@coeng.uobaghdad.edu.iq :البريد االلكتروني* المستخلص التوصيل ان هذا البحث من المؤمل ان يحقق هدف تقييم سلوك فعالية الجرافين الوميضي المستخدم في عملية تحسين وتقليل قيمة )االس الهيدروجيني و الحقيقية التي تم اخذها من ابار محطة بحوث الرائد وهذه المياه تستخدم في قطاع الزراعة و استصالح الكهربائي وتراكيز الكتيونات والحديد( في المياه الجوفية ة االغذية والزراعة االراضي ، وعلى ان تصل التراكيز للملوثات بعد تقليليها في المياه الجوفية الحقيقة الى مستوى تركيز مساوي للمعايير العراقية ومنظم ة .تم استخدام الجرافين الوميضي في تجارب الدفعات بتقنية االمتزاز وهو مادة ذات اساس كاربوني عالية المسامية لها قابلية امتزاز عالي العالمية لمياه الري حّضر من غم. تم تصميم وتصنيع جهاز لتحضير الجرافين الوميضي والذي يحّول الكاربون المنشط الم\2( م71,7بسبب المساحة السطحية الفعالة البالغة ) ( ومضات لكل مرة تشغيل. 10-8قشور الموز وذلك بتعّرض الكربون المنشط الى ومضات كهربائية ناتجة عن تشغيل الجهاز وغلق الدورة الكهربائية فيه لـ) ، ان فعالية االمتزاز في تجارب (sem , ftir, xrd, edx) ان الشكل السطحي للجرافين الوميضي ومجاميع االمتزاز الفعالة له تم توصيفها ب تحليل ( غم من 1,5للحديد عند اعلى كمية للمادة المستخدمة البالغة ) %100للمواد الصلبة الذائبة الكلية و %61للمغنسيوم و %69للكالسيوم و %69الدفعات كانت ( لالس الهيدروجيني . ان قابلية 7الدقيقة عند قيمة )( دورة في 150ساعات وبسرعة اهتزازية ) 4( مل من المياه الجوفية ولمدة 100الغرافين الوميضي لكل ) موديل مع تطابقت والتي الوميضي للجرافين = (freundlich) االمتزاز للكالسيوم = \ملغم 14,6كانت للمغنسيوم و = \ملغم 16,4غم وللحديد غم غم . واخيرا فان استخدامالجرافين الوميضي المصنع كان ضمن عوامل محددة تم تغييرها وتعديلها \ملغم 7,3غم وللمواد الصلبة المذابة الكلية = \ملغم0,074 من التالمس بين المادة المازة والعناصر الملوثة في المياه و االس الهيدروجيني للمياه الجوفية( حيث تمت باستمرار )كمية المادة المازة ، سرعة االهتزاز، ز الم الدفعات باالمتزاز تحسين نوعية الكهربائي واالس بواسطة تجارب التوصيل الكلية وقيمة الذائبة الكتيونات والحديد والمواد الصلبة لتراكيز الجوفية ياه الهيدروجيني وفقا للمعايير المحددة في نهاية هذه التجارب mailto:nawra.sobhi2311@coeng.uobaghdad.edu.iq this is an open access article under the cc by license : al-khwarizmi engineering journal al-khwarizmi engineering journal issn (printed): 1818 – 1171, issn (online): 2312 – 0789 vol. 21, no. 4, december, (2025), pp. 125135 thermal comfort and internal conditions testing of standard relief tents in cold climates rawan a. fayyad1* and issam m. ali aljubury2 1,2 department of mechanical engineering, college of engineering, university of baghdad, 10071, baghdad, iraq *corresponding author’s email: rawan.adnan2303@coeng.uobaghdad.edu.iq )received 5 may 2025; revised 7 july 2025; accepted 3 august 2025; published 1 december 2025 ( https://doi.org/10.22153/kej.2025.08.004 abstract to assist decision-makers in selecting the best solutions and arriving at better solutions for temporary shelter and to identify key issues related to temporary shelter methods and provide some principles and recommendations, this study presented a theoretical investigation into the measurement of thermal comfort in standard relief tents in cold climates. the results were analysed and compared using the cbe mrt and cbe thermal comfort tools based on field-measured values inside a tent from december 2024 to february 2025. the results on 11, 13, 14 and 18 december 2024, were selected to avoid repetition. thermal comfort is a key factor in the design and use of tents in cold regions because of its direct impact on the safety and well-being of occupants. factors affecting the thermal comfort of tents in cold weather include insulation, ventilation, clothing and heating. this study was applied in nature and was conducted using a descriptive analytical approach. data were collected using library and documentation methods. this study provides important indicators in the field of thermal comfort, particularly in the design of heating, ventilation and air conditioning systems. these environmental and individual factors influence the relationship between the predicted population mean vote and the predicted dissatisfaction rate. on the basis of these factors, the study helps measure human indoor thermal comfort and determine the influencing factors in each case to reach the desired conclusions while emphasising that the tents did not provide suitable thermal conditions for their inhabitants until they were treated using an experimental model. keywords: temporary shelter; thermal comfort; cbe mrt; cbe thermal comfort tools; pmv; ppd 1. introduction the centre for the built environment (cbe) thermal comfort tool is a widely used tool for calculating and visualising thermal comfort in accordance with ashrae 55[1], iso 7730[2], and en 16798[3]. other main thermal comfort models include pmv, standard effective temperature (set), adaptive models, local discomfort models, solar call, and dynamic predictive clothing insulation. our technology offers interactive and dynamic visualisations of thermal comfort zones. more than 49,000 people worldwide use the cbe thermal comfort tool annually, including engineers, architects, researchers, educators, facility managers, and policymakers. the tool has many practical applications. currently, 45 million people have been displaced worldwide because of conflict, natural disasters or other calamities. the frequency of extreme weather and climatic occurrences adds to the complexity and intensity of the global natural disaster scenario. the affected nations and areas usually lack the capacity to handle such calamities. refugees are people who have been displaced and have crossed a border to seek safety in another nation. the united nations high commissioner for refugees (unhcr) has two missions under these circumstances: protection and aid. in addition mailto:rawan.adnan2303@coeng.uobaghdad.edu.iq https://doi.org/10.22153/kej.2025.08.004 rawan a. fayyad al-khwarizmi engineering journal, vol. 4, no. 2, p.p. 125-135 (2025) 126 to registering the refugees and giving them legal status, the unhcr oversees the aid effort. mass population displacements frequently result in high mortality rates. the population’s quality of life and chances of survival will increase with the speed and adaptability of the response. governments frequently use temporary buildings, such as relief tents, to distribute goods for disaster relief and to help impacted communities relocate in a transitional manner [4]. disaster relief tents are often used as essential emergency rescue tools during temporary shelter phases. however, as with other temporary structures, the nature of their construction results in poor thermal resistance, heat loss and limited heat storage capacity. as a result, the inhabitants of these tents often suffer from severe cold during the winter and stifling, harsh conditions during the summer [5]. this problem occurs because the temperature inside the tents rises quickly in direct sunshine and falls quickly when the outside temperature drops [6] as a result of the structure’s lack of thermal capacity. to improve the internal microclimate of tents, studies have been conducted on changing the structure of materials [7], adding more layers [8], and developing layer technology and external partitions [9] for the tents. experiments have demonstrated that adding a reflective layer to the tent’s outer layer lowers the air temperature [10][11]. the thermal insulation of building walls also greatly enhanced by reflective insulation [12]. tent partition modifications and the application of various thermal insulation layers [13] have been shown to reduce heating and cooling loads while maintaining acceptable thermal comfort levels for occupants [14]. according to bradshaw [15], buildings are designed to create an artificial environment that is better suited for human use or specific processes than the surrounding outdoor conditions. therefore, maintaining a distinct indoor thermal environment is essential, as it usually differs significantly from external climatic conditions. this indoor climate can be influenced through passive envelope features or actively controlled using environmental systems. in emergency situations, addressing all factors that influence the planning of temporary housing is often impractical. additionally, each affected region has unique characteristics that shape the suitability of different sheltering technologies. a planning model that considers human error and evaluates the interaction between existing and newly implemented infrastructure is crucial for improving preparedness in the pre-disaster phase. crisis risks can be mitigated through proper planning, community preparedness, and enhanced resilience. this can be achieved by adopting a systematic temporary housing strategy for each location that relies on local data and outlines key actions required during preand post-disaster periods. this article introduces a structured approach to temporary housing design, viewed as a sequence of steps aimed at addressing occupant needs and improving the internal conditions inside tents. the discussion highlights that relying solely on solar energy is insufficient for maintaining adequate heating in lightweight shelters unless an integrated solar heating system is implemented. haiqal et al. [16] evaluated the thermal comfort performance of refugee tents by combining ansys fluent simulations with field observations in a humid tropical region. their study tested two design improvements rooftop vents and a doubleskin roof with a 10 cm air gap. ventilation alone reduced indoor air temperature by approximately 0.5 k, while the double-skin design further decreased indoor temperature by about 2.9 k relative to the outdoors. these modifications also enhanced airflow, demonstrating the value of improved insulation and ventilation strategies for shelters in humid climates [21]. using local high-thermal-mass materials, eltaweel et al. created an inverted-box-rib modular shelter known as makazi. compared to lightweight alternatives, these shelters exhibited smaller temperature fluctuations an important advantage in regions with large diurnal temperature variability, as confirmed by energyplus simulations. this approach balances rapid construction, cultural compatibility, and improved occupant comfort [22]. through ida-ice simulations and field measurements, ibrahim et al. examined evolving design strategies across multiple phases of prototype refugee housing. their findings indicated that passive approaches such as solar shading and thermal insulation significantly improved indoor thermal performance. although later prototypes achieved substantial reductions in heating and cooling demands and enhanced thermal comfort, active systems were still required during winter in cold climates [23]. rupp, vásquez, and lamberts reviewed a large number of thermal comfort studies although not specific to temporary shelters. their analysis highlighted the influence of local controls, occupant adaptability, air movement, and mean radiant temperature on comfort. they concluded that thermal comfort is shaped by a combination of passive design features, occupant behaviour, and rawan a. fayyad al-khwarizmi engineering journal, vol. 4, no. 2, p.p. 125-135 (2025) 127 adaptive management, especially in lowperformance temporary structures [24]. overall, this study aims to evaluate the internal thermal conditions of emergency shelters and assess the thermal comfort performance of standard relief tents to inform design improvements suited for various climate conditions. 2. methodology thermal environment and thermal comfort tests of standard relief tents were conducted in a low temperature environment to determine the heat transfer coefficient value of the thermal cover of the air tent. these data can be used in case of plans to use heating inside the tent (fig. 1). the study was conducted under cold climatic conditions in december in thi-qar/nasiriyah, iraq. the relationships between the predicted percentage of dissatisfied (ppd) you can just write ppd. and predicted mean vote (pmv) were adopted, and their values were calculated mathematically and compared with their values obtained by using cbe and cbe 3d mrt software. 3. climate of nasiriyah city nasiriyah is a city in iraq situated along the banks of the euphrates river, about 360 km southeast of baghdad at 46.26 longitude, 31.7 latitude and an elevation of 10 m above sea level. the winter months are december, january and february. 4. thermal comfort the design and operation of indoor environments and the assessment of indoor thermal environments depend heavily on thermal comfort. thermal comfort is defined as the “state of mind which reflects happiness with the thermal environment” according to iso standard 7730 [2]. over the past few decades, academics have thoroughly examined and discussed two kinds of thermal comfort techniques. globally, indoor thermal comfort in buildings is predicted and evaluated using fanger’s ppd and pmv indices [19]. the indicators are derived from laboratory research and supported by the idea that the body’s heat balance and metabolic heat generation indicate how people react to their thermal surroundings in terms of heat transfer physics and physiology. according to the steady-state heat balance model, the effects of thermal load on the human thermoregulatory system’s effect mechanisms are strongly linked to thermal sensation. this method is reliable because it allows hvac engineers to create an indoor environment by calculating radiant temperature for radiant heating and cooling system design and indoor thermal design parameters such as air temperature, humidity, and air speed for heating and cooling load calculations. 5. thermal comfort indices with air speed, air temperature, humidity, metabolic rate, clothing levels and global temperature taken into account, the thermal comfort indices can be calculated as follows: pmv (predictive mean vote) the percentage of thermally unsatisfied individ uals who feel either too warm or too chilly is deter mined by the ppd index. it forecasts how many pe ople in a bigger group will be thermally displeased. draught risk is the proportion of people who are expected to experience discomfort due to draught. 6. pmv and ppd pmv is a metric used in the field of thermal comfort and indoor environmental quality to estimate the thermal perception of a group of occupants in a given indoor space. the pmv model was developed by fanger in the 1970s [4] and is based on the heat balance of the human body. the pmv index utilises six key factors to determine the thermal sensation: air temperature, mrt, air velocity, humidity, clothing insulation and metabolic rate [16]. the model is based on the idea of thermal sensation, which is quantified on a scale ranging from -3 (representing cold) to +3 (representing heat), with 0 denoting a neutral or pleasant condition [17]. ppd is a metric used to predict the level of dissatisfaction in a population on the basis of certain factors, such as environmental conditions, personal preferences or specific criteria of interest. it is widely used in fields such as building performance, architecture and environmental science, particularly in the context of indoor environmental quality. rawan a. fayyad al-khwarizmi engineering journal, vol. 4, no. 2, p.p. 125-135 (2025) 128 in indoor climate assessment (such as thermal comfort), ppd is calculated the basis of the pmv model, which estimates the average response of a population to a certain set of environmental conditions such as temperature, humidity, air velocity and clothing insulation. ppd: on the basis of the pmv value, the ppd estimates the percentage of people who are likely to be dissatisfied with the thermal conditions. a higher ppd indicates a higher likelihood of dissatisfaction. pmv model considers six main factors that affect human thermal comfort: air temperature: the temperature of the air surrounding a person. mrt: the average temperature of surfaces that radiate heat towards the person (e.g. walls, windows or floors). air velocity: the speed of the air moving around a person, which can influence how heat is dissipated from the body. relative humidity: the quantity of moisture in the air that influences the body’s capacity to cool itself through evaporation. clothing insulation: the amount of thermal insulation provided by the clothing a person is wearing. metabolic rate: the amount of heat produced by the human body due to physical activity. relationship between pmv and ppd: as pmv moves away from 0 (neutral), ppd increases. for instance: pmv = 0 → ppd ≈ 5% (comfortably neutral) pmv = −1 or +1 → ppd ≈ 25% pmv = −2 or +2 → ppd ≈ 50% ppd calculation: ppd is mathematically linked to pmv, as in equation (1). as pmv moves further from zero (i.e. the neutral comfort zone), ppd increases. the relationship between pmv and ppd is described by the following equation [25]: ppd=100-95e(-0.0335(pmv))4-0.2179(pmv)2 ... (1) where e is the mathematical constant (euler’s number). this formula illustrates how ppd grows expone ntially in either the positive (hot) or negative (cold) direction as pmv travels farther from zero. ppd is the predicted percentage of dissatisfied people (in%), and pmv is the predicted mean vote on the thermal sensation scale. 7. experimental work 7.1 testing the properties of standard relief tents the shelter consists of the following parts: roof panels: polyolefin foam panels treated with uv protection. door: highly resistant door and hinges with locks, which can be padlocked from both sides for added safety for women and children. floor sheet: height-adjustable, flood-preventing tarpaulin made of woven high-density polyethylene fibres. window: intrusion prevention window with mosquito net and shade made of uvand heatresistant polymer plastic wall panels: polyolefin foam panels treated with fire retardant and uv protection. ventilation: uvand heat-resistant polymer plastic. figure (1) shows the tent features. 7.2. tent features table 1, tent features no. part 1 lockable door 2 four windows 3 four ventilations 4 semi-rigid, opaque roof and wall panels 5 steel frame mounted with ground anchors 6 pv system and portable lamp 7 flat-packed 8 five-year shelf life 9 minimum three-year life span for panels 10 minimum 10 years for frame 11 four to six hours assembly time by a team of four 7.3. tent measurements table 2, tent measurements size 17.5 m3/188.4 ft3 length 5.68 m or 18.6 ft. width 3.32 m or 10.9 ft. height 2.83 m or 9.2 ft. weight 160 kg or 352.7 lb. (shelter 140 kg/packaging 20 kg) rawan a. fayyad al-khwarizmi engineering journal, vol. 4, no. 2, p.p. 125-135 (2025) 129 (a) (b) fig. 1. (a) srts (b) top, front and side view [20] 7.4. tent specification • 101 km/h or 28 m/s wind resistance • withstands 10 kg/m2 snow load • minimum 2-minute escape time • passes artificial rain test with no leakage 7.5. thermal comfort test of the tent the most important measuring devices utilised in this study before the thermal comfort assessment of the tent was conducted are listed below. 7.5.1. measuring instrument (digital beehive thermometer) a) temperature sensors: digital thermometers or temperature data loggers were used inside and outside the tent to monitor the internal and external temperature as temperature plays an important role in determining the suitability of thermal conditions. the temperature measurement range was from −50 °c to 70 °c, and the temperature measurement accuracy was ±1 °c. b) humidity sensors: hygrometers help monitor the relative humidity inside the tent. thus, humidity monitoring devices were installed inside the tent, and the values were compared with the external humidity. the humidity measurement range was (10% _ 95% )rh, and the humidity measurement accuracy was ±5%. fig. 2. temperature and humidity sensor 7.5.2. test procedures initial condition setup: the tent was set up according to the manufacturer’s instructions (e.g. proper installation, tensioning). in particular, the environment surrounding the tent had to be stable and documented. preconditioning: the tent had to be preconditioned by exposing it to certain temperatures or humidity levels before testing. rawan a. fayyad al-khwarizmi engineering journal, vol. 4, no. 2, p.p. 125-135 (2025) 130 this step was conducted in november before the start of testing. testing of various parameters: • without occupants: the thermal performance of the tent was verified in empty conditions without occupants. • with occupants: temperature sensors or body simulators were used inside the tent to assess how the presence of people affected temperature and comfort, with the manufacturer allowing four occupants. temperature gradients: the temperature difference between inside and outside the tent was monitored on 11–18 december 2024, which were extremely cold days, with temperatures reaching below 0 °c at night while being slightly higher during the day. 8. result and conclusion table 3, results of the cbe tool december day pmv ppd sensation set 12 −2.25 87% cool 17.9 13 −2.2 85% cool 18 14 −1.92 73% cool 19.2 15 −4.05 100% cold 11.9 the data gathered via the cbe interface and shown in table (3) indicated that the thermal performance within the tent was insufficient because the inside temperature was almost similar to the outside temperature and the th ermal conditions were not appropriate for adequate housing. the cbe and cbe 3d mrt results show that the tents in the cold environment did not meet the needs of their inhabitants. the indoor thermal comfort conditions were also unsuitable in cold weather as the indoor and outdoor conditions were almost equal, which means that displaced people would continue to experience the same problem. this problem can only be solved with the development of an advanced solar system. figures 3(a–d) show the relationship between humidity and operating temperature on 11–18 december and their effects on ppd, pmv, sensation and set on the basis of other variables used in cbe, such as mrt, air temperature, metabolic rate and clothing level. overall, thermal comfort was observed on the basis of the variable values and their effects on pmv and ppd. the pmv values ranged from 2.2 to 4. according to the pmv scale, thermal sensation indicates that indoor conditions were cool to very cold. ppd values are based on pmv values, with pmv resulting in a ppd of approximately 75%, meaning that most people felt uncomfortable. figures 4(a–d) show the thermal comfort through the relationship between relative humidity and dry-bulb temperature for the same days and variables. (a) (b) (c) rawan a. fayyad al-khwarizmi engineering journal, vol. 4, no. 2, p.p. 125-135 (2025) 131 (d) fig. 3. comfort zone for thermal comfort based on operating temperature and humidity ratio values, as defined by ashrae 55 standard, showing the range of acceptable indoor conditions. the operating temperature is represented by the abscissa in this psychrometric chart (fig. 3), and the mrt (dbt = mrt) is equal to the dry-bulb temperature for each location. according to the standard, the comfort zone is the set of circumstances with the same dbt and mrt for which the pmv falls between −0.5 and +0.5. the standard has limited applicability, covering only healthy people. occupants who are sleeping, reclined while in contact with bedding or able to alter blankets or bedding wearing extremely impermeable clothes or whose clothing insulation exceeds 1.5 clo are exempt from this guideline. (a) (b) (c) (d) fig. 4. comfort zone according to the dry-bulb temperature and humidity ratio values based on en 16798-1. rawan a. fayyad al-khwarizmi engineering journal, vol. 4, no. 2, p.p. 125-135 (2025) 132 the dry-bulb temperature is the abscissa in this psychrometric chart (fig. 4), and the input box controls the fixed mrt. the comfort zone boundary is defined by the same mrt at each place on the chart. illustrates how modifications to mrt impact thermal comfort. each point will have the same mrt, but the operational temperature button can still be used. while the cbe thermal comfort tool computes the relative air speed automatically, it does not compute the dynamic insulating properties of clothing as required by iso 7730 section c.2. therefore, the user should compute this value and enter it into the cbe thermal comfort tool. figures 5(a–d) illustrate cbe’s 3d mrt tool, an interactive tool that uses room surface temperatures, solar gain from windows and skylights, and the mrt to determine and display the expected comfort level in a given space. this tool allows for the input of variables related to thermal comfort, including clothing levels and metabolic rates. the figures model a 3d space, including windows and skylights, and then display graphical outputs showing the average radiant temperature, or comfort, represented by the predicted mrt, spread over the space. this tool shows how radiant heat is distributed within the tent, thus helping identify areas of excessive coldness or heat. it enables researchers to test the effect of design modifications, such as adding insulation, curtains or vents, on improving thermal comfort. (a) (b) (c) (d) fig. 5. comfort zone in the cbe 3d mrt tool http://centerforthebuiltenvironment.github.io/mrt/ rawan a. fayyad al-khwarizmi engineering journal, vol. 4, no. 2, p.p. 125-135 (2025) 133 9. conclusion the comfort finding was based on the idea that the key input for thermal sensation and comfort perception is provided by thermoreceptors, which are sensitive to core and skin temperatures. fanger’s pmv model (fanger, 1972) and the current approach have been shown to predict similar comfort zones for non-stratified situations, even though the latter relies on a general thermal balance between the environment and the human body. however, the cbe model’s prediction of the chilly limit of the comfort zone was less accurate than that of the pmv model. the tent’s thermal comfort was tested by creating a variety of environmental scenarios and measuring interior and external variables that influence comfort, including temperature, humidity and airflow, using a variety of sensors. the outcomes were used to evaluate how well the tent maintained a cozy interior atmosphere. additionally, a variety of factors influenced the tents’ interior conditions, and findings indicate that depending solely on solar energy was not enough to guarantee suitable comfort levels, especially in the winter. the walls, floors, tent insulation and the precise places where the tents were erected were all deemed crucial components in the study. srts were tested during winter, specifically on 11–18 december 2024, when daytime and nighttime temperatures were extremely low. the cbe tool, which is intended to compute and show thermal comfort in compliance with ashrae standards, was used to simulate the thermal comfort conditions. on the basis of the results of this study, the following conclusions can be drawn: 1. relying on solar radiation alone in building the heating system is insufficient because it does not provide the required thermal comfort, especially in cloudy weather, and the problem of providing suitable housing is not solved. 2. the parameters that pmv and ppd rely on, such as temperature, humidity, air velocity, clothing insulation and metabolic rate, can greatly impro ve the interior conditions, according to the pm v and ppd readings that were used to determin e the tent’s internal thermal comfort level in acc ordance with the cbe tool. 3. the proposed theoretical model was mainly based on the values obtained experimentally during certain days in december. funding source the experimental work was funded by the united nations high commissioner for refugees in iraq. data availability the data supporting the findings of this study were obtained by the corresponding author. the authors thank the united nations high commissioner for refugees in iraq for providing tents for the purpose of conducting the study, the university of baghdad for providing laboratory support, colleagues who assisted in the experimental work, and professor dr. issam mohammed ali for his continuous follow-up and supervision of the completion of the work. nomenclature srts standard relief tents hvac heating, ventilation, and air conditioning pmv predicted population mean vote ppd predicted dissatisfaction rate (in %) set standard effective temperature cbe center for the built environment unhcr united nations high commissioner for refugees e mathematical constant (euler’s number) references [1] ashrae, standard 55-2004: thermal environmental conditions for human occupancy. american society of heating, refrigeration and air-conditioning engineers, atlanta, 2004. 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[23] h. ibrahim, t. ahmad, and m. el-shafie, “energy use and indoor environment performance in sustainably designed refugee shelters,” energy and buildings, vol. 288, 112987, 2023. [24] r. f. rupp, n. g. vásquez, and r. lamberts, “a review of human thermal comfort in the built environment,” energy and buildings, 2021. [25] c. croitoru, i. nastase, f. bode, a. meslem, and a. dogeanu, “thermal comfort models for indoor spaces and vehicles—current capabilities and future perspectives,” renewable and sustainable energy reviews, vol. 44, pp. 304–318, 2015. http://www.bettershelter.org/ ( 2025) 125-135، صفحة 4، العدد21مجلة الخوارزمي الهندسية المجلدروان عدنان 135 ( في المناخات الباردةsrtsاختبار الراحة الحرارية والظروف الداخلية لخيام اإلغاثة القياسية ) 2، عصام محمد علي الجبوري*1روان عدنان فياض قسم الهندسة الميكانيكية، كلية الهندسة، جامعة بغداد، بغداد، العراق 1،2 rawan.adnan2303@coeng.uobaghdad.edu.iq االلكتروني: *البريد المستخلص لقلة لمساعدة صانعي القرار في اختيار أفضل الحلول والتوصلل لللح وللول أفضلل للمللوؤ المتقلف، لهلدس الدراسلة لللح لحديلد القضلايا الر يسلية المتع ( فلي srtsياسلية بلساليب الملوؤ المتقف ولقديم بعض المبادئ والتوصيات. قدمف هذه الدراسة بحثًا نظريًا في قياس الراوة الحرارية فلي خيلاا ااثا لة الق بناًء علح القيم المقاسة ميلدانيًا داخلل الخيملة فلي cbe thermal comfortو cbe mrtالمناخات الباردة. لم لحليل النتا ج ومقارنتها باستخداا أدوات . نظًرا لتل يرها المباشر علح سالمة ورفاهية شاثليها، لُعد الراوة الحرارية عامالً ر يسيًا في لصميم واستخداا الخياا فلي 2024ديسمبر 15و 14و 13و 12 ت رة علح الراوة الحرارية للخياا في الطقس البارد العزل والتهوية والمالبس والتدفئلة. هلذه الدراسلة لطبيقيلة فلي الطبيعلة المناطق الباردة. لشمل العوامل الم ولة الحراريلة، وأُجريف باستخداا نهج لحليلي وصفي. لم جمع البيانات باستخداا أساليب المكتبة والتو يق. لوفر هلذه الدراسلة متشلرات مهملة فلي مللال الرا لصلويف السلكاا المتوقلع (. لت ر هذه العوامل البيئية والفردية علح العالقلة بليم متوسل hvacوخاصة في لصميم أنظمة التدفئة والتهوية ولكييف الهواء pmv ومعدل عدا الرضا المتوقع )ppd بناًء علح هذه العوامل، لساعد الدراسة علح قياس الراوة الحرارية الداخلية لإلنسلاا ولحديلد العواملل الملت رة .) ستخداا نموذج للريبي.في كل والة للوصول للح االستنتاجات المرجوة، مع التلكيد علح أا الخياا لم لوفر ظروفًا ورارية مناسبة لساكنيها لال بعد معاللتها با mailto:rawan.adnan2303@coeng.uobaghdad.edu.iq*البريد